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1. Field of the Invention
The present invention relates to a closed caption control apparatus which is used by being built into or connected to a video playback apparatus, an audio playback apparatus, a video record-playback apparatus, or an audio record-playback apparatus, and which controls displaying of closed caption and other character information; and a method therefor.
2. Description of the Related Art
In playing-back video contents of television broadcasting or a DVD (Digital Versatile Disc) or the like, closed caption information for complementing audio information output along with video is provided. In a case of the television broadcasting, closed caption information is formed from teletex signals embedded in video signals, and transmitted by using identification signals (VBI signals) inserted into a vertical blanking interval. On a DVD or the like, multi-lingual closed caption information can be recorded along with video and audio. Further, in a case of digital high-vision broadcasting, closed caption information can be transmitted as sub video information.
It can be thought that the utilization of closed caption information is effective in a case where to hear the speech corresponding to an image is hard for not only a hearing impairment person or a defective hearing person, but also a person with normal hearing. For example, there are cases in which a background noise or music (BGM) mixed in a speech interferes hearing of the speech contents. Further, it goes without saying the case where a speed of speech to be heard is fast, and in a case where the speed of speech is extremely slow as well, it is hard even for the person with normal hearing to exactly listen the speech.
A technique in which a mode for displaying closed caption information corresponding to speech contents or the like is controlled in accordance with a difficulty in listening of the speech contents has been not realized yet in a conventional video playback apparatus or information display device.
On the other hand, several techniques of analyzing audio information have been known. For example, with regard to a determination on background noise, a method for estimating an SN ratio of input audio which is aimed for suppressing noise (for example, refer to Jpn. Pat. Appln. KOKAI Publication No. 7-306695) is well known. Further, with regard to a determination on musical sound, a method based on an autocorrelation coefficient of sound data (for example, refer to Jpn. Pat. Appln. KOKAI Publication No. 5-113797) is well known. Moreover, with regard to an estimation of a speed of speech, a method based on a dynamic features of a sound signal (for example, refer to Jpn. Pat. Appln. KOKAI Publication No. 5-289691) is well known.
An object of the present invention is to provide a closed caption control apparatus to display complementary closed caption information such that the contents of speech can be appropriately and exactly delivered to a viewer even in a situation in which it is hard to hear a speech in audio output, or control a mode for displaying the closed caption information, and a method therefor. | {
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1. Field of the Invention
The present invention relates to an operating field securing device which comes into contact with an internal organ such as the heart to perform various procedures and the like during surgery on the internal organ.
2. Description of the Related Art
In conventional cardiac surgery, the chest cavity is accessed by incising a breast bone (median breast bone incision). Moreover, when the chest cavity is accessed as described above, a retractor is disposed at a position of the breast to be incised, and the breast bone and tissue are spread by the retractor, thereby forming a large opening. Then, a surgical instrument is disposed through the opening to perform the cardiac surgery.
Meanwhile, one of the most general types of cardiac surgery is coronary artery bypass grafting (CABG). In CABG, when one or a plurality of coronary arteries are blocked, the coronary artery on the downstream side of this blockage is connected to a transplanted blood vessel (hereinafter referred to as the graft) to provide a bypass.
A technology for connecting the graft to the coronary artery in this manner is known as anastomasis. As the above graft, for example, a thoracic artery incised from a chest wall is used. In this case, the upstream end of the thoracic artery is left undamaged, and the downstream end of the thoracic artery is connected to the coronary artery.
Moreover, as the graft; an artery or a vein from any part of a patient's body may be used. Furthermore, an artificial blood vessel graft may be used as the graft. In this case, the upstream end of the graft is connected to an artery such as an aorta, and the downstream end thereof is connected to the coronary artery. As described above, a plurality of blocked coronary arteries at various positions of the front, side and back of the heart are bypassed by using a plurality of grafts.
It is to be noted that CABG is performed while the patient's heart is stopped. Therefore, the patient's blood is circulated by using an artificial heart-lung device. However, CABG may be performed by using a technology known as “off-pump coronary artery bypass” (OPCAB) while the heart is beating. That is, the use of the artificial heart-lung device can be avoided owing to OPCAB.
In OPCAB, while the heart is beating, the surface of the heart near the region of the coronary artery to be anastomosed is fixed by using a special instrument referred to as a stabilizer. Since the surface of the heart is locally fixed by this stabilizer, the region to be anastomosed is kept to be as immobile as possible while the graft is connected to the coronary artery.
Here, the stabilizer includes, for example, a contact portion which comes in contact with the surface of an internal organ, and a flexible contact portion support portion for supporting the contact portion. The contact portion support portion is constituted of a plurality of joining members so that the contact portion support portion can be bent or deformed.
Moreover, an elongated cable such as a wire is extended through the joining members. The tension of this cable is appropriately regulated to bend or deform the contact portion support portion, thereby inserting the contact portion support portion into the chest cavity. Then, the contact portion is brought into contact with a target region of the surface of the heart in the chest cavity, and the surface of the heart is pressed or adsorbed by the contact portion to suppress the vibration of the heart. Since the vibration of the heart is suppressed in this manner, an operating field securing device including a manipulator for performing various surgical procedures can be used to accurately operate on the heart. It is to be noted that the above technology concerning the stabilizer is disposed in, for example, Japanese Patent Publication No. 2003-521296. | {
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1. Field of the Invention
The present invention relates to a method of applying image data as a visually detectable pattern at an optical record carrier.
The present invention further relates to an apparatus for applying image data as a visually detectable pattern at an optical record carrier.
The present invention still further relates to an optical record carrier having applied thereon image data in the form of a visually detectable pattern.
2. Related Art
A visually detectable pattern comprises for example a logo, a sequence of characters or a combination thereof. The visually detectable pattern is printed at a resolution suitable for detection by the human visual system. For example the visually detectable pattern may be printed at a resolution of 1 to several hundreds dots per mm2 (as compared to computer readable data, which is stored at the record carrier at a resolution in the order of several Mbits/mm2). In this way, a user does not need a reading device to recognize the contents of the optical disk, but a simple visual inspection suffices. Such a visually detectable pattern can also serve as a means to detect the authenticity of the record carrier.
A method and a device for providing a watermark at a record carrier is disclosed in EP 1,710,896. According to the method described therein, a parameter of the channel code is controlled to introduce a predetermined run-length distribution. In particular, said parameter is the choice of the merging bits used in the channel code. Introduction of the run-length distribution results in a visually detectable pattern. The contrast of this pattern is weak, however. Moreover, the presence of data embedded in the visually detectable pattern diminishes the visibility of the image data represented by the pattern. There is a need to apply a visually detectable pattern at an optical record carrier having an improved visibility. | {
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This invention relates to integrated circuits and, more particularly, to integrated circuit comparators.
A comparator is a circuit that compares the instantaneous magnitude of a first input signal to the magnitude of a second input signal. If the magnitude of the first input signal is less than the magnitude of the second input signal, then the comparator generates an output signal having a first logic level. If the magnitude of the first input signal is greater than the magnitude of the second input signal, then the comparator generates an output signal having a second logic level.
An ideal comparator has infinite gain and infinite bandwidth. A comparator having infinite gain and infinite bandwidth can convert a small analog signal to a large logic signal very quickly. Unfortunately, most comparators are not ideal. The gain of most high-bandwidth comparators is usually low, less than about ten, and the bandwidth of most high-gain comparators is also low, less than about one megahertz. For some comparator applications, such as detecting a light level change in a smoke detector, the gain-bandwidth product is not critical to the success of the application. A comparator having a gain of about ten and a bandwidth of about one megahertz is suitable for use in connection with a smoke detector. However, there is a great demand for comparators that can operate in high-speed signaling applications that are common in modem digital systems, such as microprocessors, digital signal processors, communications circuits, and storage systems. These high-speed signaling applications require the comparator gain to be as high as possible, usually much greater than ten, and the comparator bandwidth also to be as high as possible, usually much greater than one megahertz.
For these an other reasons there is a need for a comparator having a high gain-bandwidth product. | {
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In order to properly receive a block oriented digital communication signal, such as orthogonal frequency division multiplexed (OFDM) or discrete multi-tone (DMT) that has been transmitted across a channel, and demodulate the symbols from the received signal, a receiver must determine the timing of the beginning of each symbol within a data frame. If the correct timing is not determined, sequences of symbols demodulated from the received signal will more likely be incorrect, resulting in the transmitted data bits not being correctly recovered.
Also, OFDM and DMT are often used in hostile environments such as networks deployed over home power lines where interference from narrow-band jamming signals can be problematic.
There is therefore a need for a computationally efficient system and method for detecting a time shift required for symbol synchronization of an OFDM or DMT signal that allows a simple means of eliminating narrow-band jamming signals. | {
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1. Field of the Invention
The present invention relates to an aqueous ink using a dispersible colorant and a water-soluble nonionic resin and/or an emulsion particle, an ink jet recording apparatus, an ink jet recording method, and an inkjet recorded image.
2. Related Background Art
The ink jet recording system adopts various working principles to produce images, letters or the like by ejecting fine ink droplets from nozzles onto a recording medium (paper or the like). It has been rapidly spreading in various uses because of their advantages of high speed, low noise, capacity of easily producing multi-color images, high flexibility of recorded patterns, and unnecessity of development/fixation. In particular, the full-color aqueous ink jet recording system techniques have recently made remarkable progress, and can now produce multi-color images which are by no means inferior to those by the conventional printing method or photography. It has been widely applied to the full-color image recording area, because of its capacity of producing printed matter at a lower cost than the conventional printing method or photography, when the number of copies is limited.
The ink jet recording apparatus and recording method using an aqueous ink have been improved to satisfy the requirements for improved recording characteristics, such as higher speed, finer images and full-color images. In general, the aqueous ink used for an ink jet recording apparatus is required to have the following performances; (1) even images of high resolution and high density can be obtained without occurrence of bleeding or fogging on paper, (2) the ink is ejected without being dried at the nozzle tips to prevent clogging there while keeping good ejection response and ejection stability, (3) the ink can be well fixed on paper, (4) the images have good weatherfastness, and (5) the images are stable for a long period of time. Especially, an ink that is dried and fixed rapidly and provides printing of high image-quality is being required with a recent increase in printing speed.
Colorants for use in the ink jet recording with an aqueous ink mainly include a dye and a pigment. Water-soluble dyes have hitherto been mainly used because of their handleability as aqueous inks and good color developability. More recently, however, essentially water-insoluble colorants, particularly pigments, have been extensively developed as colorants for aqueous inks for ink jet recording which can realize higher weatherfastness of produced images. For allowing a water-insoluble colorant, particularly pigment, to be used for aqueous inks for ink jet printing, it becomes necessary to stably disperse the colorant in water.
In this case, high dispersion stability has been generally achieved with the aid of a surfactant or polymeric dispersant (hereinafter, also referred to as dispersing resin). Further, another method has been proposed which chemically modifies the surface of a water-insoluble colorant (e.g., Japanese Patent Application Laid-Open No. H10-195360). On the other hand, a microcapsule type pigment having a pigment coated with a resin has also been proposed (e.g., Japanese Patent Application Laid-Open Nos. H08-183920 and 2003-34770). Especially, Japanese Patent Application Laid-Open No. 2003-34770 discloses an aqueous colored fine-particle dispersion comprising a water-insoluble coloring agent which is prepared by dispersing a water-insoluble coloring agent in an aqueous medium in the presence of a dispersant and then adding a vinyl monomer and polymerizing it, and which shows dispersion stability when dispersing the water-insoluble coloring agent, while the stability of the resultant latex is poor when polymerizing the vinyl monomer in the presence of only the dispersant, and describes “when emulsion-polymerized into the water-insoluble coloring agent dispersion, because the affinity of the dispersant with the vinyl monomer and resulting polymer is not so high with the result that the dispersant is difficult to be desorbed from the pigment particle surfaces and the polymerization proceeds on the dispersant-adsorbed pigment particle surfaces, the pigment-surface-coated, fine-particle dispersion can be obtained with a high yield without causing agglomeration, and further describes that by using the colored fine-particle dispersion, an aqueous ink is obtained, which is excellent in dispersion stability and printing characteristics, shows little metallic gloss, has no dependency on the paper type, and gives an image excellent in waterfastness, lightfastness and rubfastness.
However, there have been cases where these techniques do not provide dispersion stability of a colorant and gross of a recorded image sufficiently. The present inventors have made extensive study and considered that in order to improve the dispersion stability, it is necessary to increase the density of functional groups on the surface of a colorant. However, in the conventional technique using a polymeric dispersant and the technique disclosed by Japanese Patent Application Laid-Open No. H08-183920 using a resin-coated pigment, there were cases where when the acid value of a resin was increased in order to improve the dispersion stability, the hydrophilicity of the resin also increased and the resin became liable to be separated from the colorant with the elapse of time, so that the storage stability could not be maintained for a long period of time. On the other hand, with the technique of chemically modifying the surface of a water-insoluble colorant as disclosed by Japanese Patent Application Laid-Open No. H10-195360, there have been posed the problems that the modifiable functional groups and the density thereof are limited, and that effecting direct chemical modification, particularly when the colorant is an organic pigment, will cause the so-called “pigment exfoliation” in which pigment molecules, which are originally water-insoluble and crystallized, become water-soluble through bonding of hydrophilic groups to be dissolved out from pigment particles, thereby significantly change the hue (see FIGS. 6A and 6B). Therefore, these conventional techniques are not fully developed to sufficiently satisfy the recent requirements. | {
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The present invention relates to a PTFE aqueous dispersion composition containing fine particles of polytetrafluoroethylene (hereinafter referred to as PTFE).
PTFE by an emulsion polymerization method is usually produced by injecting and polymerizing tetrafluoroethylene (hereinafter referred to as TFE) monomer under pressure while adding and stirring a peroxide type polymerization initiator, an anionic dispersant and a higher paraffin or the like as a polymerization stabilizer, to pure water. Usually, an aqueous dispersion will be obtained wherein fine particles of PTFE having an average particle size of from 0.1 to 0.5 xcexcm are dispersed at a concentration of about 30 wt % or lower.
This aqueous dispersion is very unstable by itself, and it has been common that a nonionic surfactant such as a polyoxyethylene alkyl phenyl ether, e.g. Triton X 100, manufactured by Union Carbide having a molecular structure of C8H17C6H4O(C2H4O)10H, is added for primary stabilization, followed by concentration to a PTFE solid content of from 40 to 65 wt % by a known method such as an electrical concentration method or a phase separation method. Thereafter, in order to obtain a liquid physical property such as a viscosity suitable for various applications or stabilization during storage for a long period of time, water, an antiseptic such as ammonia, a surfactant, etc., are added to obtain an aqueous dispersion composition having a PTFE concentration of from 30 to 65 wt %.
However, there has been a problem that if a frictional action or a shearing action is exerted to the conventional PTFE aqueous dispersion composition, PTFE particles tend to be fibrous and agglomerate, whereby the uniformity of the dispersion tends to be impaired.
Specifically, when a PTFE aqueous dispersion composition is transported or circulated by a pump, if the operation time prolongs, agglomerates of PTFE are likely to be formed in the PTFE aqueous dispersion composition by a frictional action or a shearing action, whereby there has been a problem that the pump is likely to be clogged, the valve operation is likely to be impaired, or the filter is likely to be clogged.
Further, there has been a problem that when an excess PTFE aqueous dispersion composition coated on a substrate such as a glass fiber cloth or a metal foil, is to be removed by a doctor bar, agglomerates of PTFE formed by a frictional action, tend to deposit on the substrate, thus leading to drawbacks such as irregularity in thickness or foreign matters to deteriorate the yield of the product.
JP-B-53-6993 proposes a method of incorporating at least 1 wt % of an alkylene oxide polymer to PTFE for the purpose of preventing sedimentation of fine particles of PTFE, but discloses nothing about stability against the frictional action or the shearing action of the liquid. The polyethylene glycol having a relatively low molecular weight i.e. a molecular weight of from 1300 to 15000 disclosed in Examples of this specification was not one having an adequate effect for improving the frictional stability.
Further, a film prepared from a PTFE aqueous dispersion composition employing a conventional polyoxyethylene alkyl phenyl ether type surfactant, has had a problem that it is likely to be colored, and the electrical characteristic such as an insulating property tends to deteriorate.
JP-A-8-269285 discloses that a film prepared from an aqueous dispersion composition employing a polyoxyethylene alkyl ether type surfactant having a cloud point of from 48 to 85xc2x0 C. and a content of ethylene oxide groups of from 65 to 70 wt %, such as RO(C2H4O)nH (wherein R is a C8-18 linear alkyl group, and n is from 5 to 20), has coloration suppressed. However, this aqueous dispersion composition has the following problem. Namely, foams formed by stirring are hardly extinguishable, and if such foams will attach, traces of foams will bring about irregularities in the thickness of the PTFE film, and the strength, etc. of the film may deteriorate, thus leading to non-uniformity, and when the aqueous dispersion composition is subjected to multi-coating to prepare a thick film, the sintered PTFE surface has a low surface tension and is repelling, whereby multi-coating tends to be difficult.
The present invention has an object to improve a PTFE aqueous dispersion composition excellent in friction stability or shearing stability.
The present invention has an object to provide a PTFE aqueous dispersion composition whereby foams formed by stirring are readily extinguishable and multi-coating is possible, and a sintered PTFE film is free from coloration.
The present invention is a polytetrafluoroethylene aqueous dispersion composition, which comprises from 30 to 65 wt % of fine particles of polytetrafluoroethylene obtainable by emulsion polymerization, from 2 to 12 wt %, based on the polytetrafluoroethylene, of a nonionic surfactant, and at least 0.01 wt % and less than 1 wt %, based on the polytetrafluoroethylene, of at least one member selected from a polyethylene oxide having an average molecular weight of from 100,000 to 2,000,000 and an association type thickener based on a water-soluble polyurethane as essential components.
The present invention is the polytetrafluoroethylene aqueous dispersion composition, wherein the nonionic surfactant is at least one member selected from nonionic surfactants having molecular structures represented by the Formulae (1) and (2):
Rxe2x80x94Oxe2x80x94Axe2x80x94Hxe2x80x83xe2x80x83(1)
(wherein R is an alkyl group having a straight chain or a branched chain represented by CxH2x+1 where x=8 to 18, and A is a polyoxyalkylene chain constituted by from 5 to 20 oxyethylene groups and from 0 to 2 oxypropylene groups)
Rxe2x80x2xe2x80x94C6H4xe2x80x94Oxe2x80x94Axe2x80x2xe2x80x94Hxe2x80x83xe2x80x83(2)
(wherein Rxe2x80x2 is an alkyl group having a straight chain or a branched chain represented by Cxxe2x80x2H2xxe2x80x2+1 where xxe2x80x2=4 to 12, and Axe2x80x2 is a polyoxyethylene chain constituted by from 5 to 20 oxyethylene groups).
Further, the present invention is the PTFE aqueous dispersion composition, wherein the nonionic surfactant is a nonionic surfactant having a molecular structure represented by the Formula (1) wherein x is from 10 to 16, and A is a polyoxyalkylene chain constituted by from 7 to 12 oxyethylene groups and from 0 to 2 oxypropylene groups.
Further, the present invention is the PTFE aqueous dispersion composition, wherein the nonionic surfactant is a nonionic surfactant having a molecular structure represented by the Formula (2) wherein xxe2x80x2 is from 10 to 16, and Axe2x80x2 is a polyoxyalkylene chain constituted by from 7 to 12 oxyethylene groups.
The present invention is a polytetrafluoroethylene aqueous dispersion composition, which comprises from 30 to 65 wt % of fine particles of polytetrafluoroethylene obtainable by emulsion polymerization, and from 2 to 12 wt %, based on the polytetrafluoroethylene, of a nonionic surfactant having a molecular structure represented by the Formula (3):
Rxe2x80x94Oxe2x80x94Bxe2x80x94Hxe2x80x83xe2x80x83(3)
(wherein R is an alkyl group having a straight chain or a branched chain represented by CxH2x+1 where x=8 to 18, and B is a polyoxyalkylene chain constituted by from 5 to 20 oxyethylene groups and from 1 to 2 oxypropylene groups).
Further, the present invention is the PTFE aqueous dispersion composition, wherein the nonionic surfactant is a nonionic surfactant having a molecular structure represented by the Formula (3) wherein x is from 10 to 16, and B is a polyoxyalkylene chain constituted by from 7 to 12 oxyethylene groups and from 1 to 2 oxypropylene groups.
The fine particles of PTFE in the PTFE aqueous dispersion composition of the present invention are those obtainable by emulsion polymerization, and they can be produced by a conventional emulsion polymerization method.
The average particle size of the fine particles of PTFE is usually within a range of from 0.1 to 0.5 xcexcm, particularly preferably within a range of from 0.15 to 0.3 xcexcm.
Further, the average molecular weight of PTFE is suitably within a range of from a 1,000,000 to 100,000,000. If it is too small, the strength of PTFE tends to be low, and if it is too large, industrial polymerization tends to be difficult.
Further, the average molecular weight is obtained from a method by Suwa et al. (Journal of Applied Polymer Science, 17, 3253xe2x80x94(1973)) using heat of crystallization obtained by differential thermal analysis.
In the present invention, PTFE includes not only a homopolymer of TFE but also a so-called modified PTFE which contains a small amount of polymer units based on a component co-polymerizable with TFE, such as a halogenated ethylene such as chlorotrifluoroethylene, a halogenated propylene such as hexafluoropropylene or a fluorovinyl ether such as a perfluoro(alkylvinyl ether) and which is not substantially melt-processable.
In the PTFE aqueous dispersion composition of the present invention, the content of the fine particles of PTFE is from 30 to 65 wt %, preferably from 50 to 62 wt %. If it is lower than the above range, the fine particles of PTFE tend to be sedimented because of a low viscosity, and if it is higher than the above range, processing tends to be difficult because of high viscosity.
In the PTFE aqueous dispersion composition of the present invention, at least one member selected from a polyoxyalkylene alkyl ether type nonionic surfactant of the above Formula (1) and a polyoxyethylene alkyl phenyl ether type nonionic surfactant of the Formula (2), is employed. In the Formulae (1) and (3), R which is a hydrophobic group, is an alkyl group, and the value of x representing the chain length of the alkyl group is within a range of from 8 to 18, preferably from 10 to 16. If x is too small, the PTFE aqueous dispersion composition tends to have a high surface tension, whereby the wettability tends to be low. Inversely, if x is too large, when the dispersion is left to stand for a long time, the fine particles of PTFE are likely to be sedimented, whereby the storage stability of the PTFE aqueous dispersion composition tends to be impaired.
Further, in the Formulae (1) and (3), if the alkyl group as a hydrophobic group, has a branched structure, the wettability will be improved, and a suitable aqueous dispersion composition can be obtained, such being preferred.
In the Formula (1), A which is a hydrophilic group, is a polyoxyalkylene chain constituted by from 5 to 20 oxyethylene groups and from 0 to 2 oxypropylene groups. A polyoxyalkylene chain constituted by from 7 to 12 oxyethylene groups and from 0 to 2 oxypropylene groups is preferred from the viewpoint of the viscosity and the stability. Particularly preferred is a case where it has from 0.5 to 1.5 oxypropylene groups in the hydrophilic group A, whereby the defoaming property will be good.
In A, the oxypropylene groups may be present in the polyoxyethylene chain or may be bonded to the polyoxyethylene chain terminals. However, when they are bonded to the polyoxyethylene chain terminals, the defoaming property will be good, and particularly when they are bonded to the molecular terminal side of the two polyoxyethylene chain terminals, the defoaming property will be better, such being preferred.
Specific examples of the nonionic surfactant of the Formula (1) include, for example, surfactants having molecular structures C13H27O(C2H4O)9-10H, C10H21CH(CH3)CH2O(C2H4O)10H, C10H21CH(CH3)CH2O(C2H4O)9-10OC3H6OH, C12H25O(C2H4O)10H, C16H33O(C2H4O)10-11H, and C10H33O(C2H4O)6-7H (provided that an alkyl group other than the branched structural moiety is of a straight chain structure, and the same applies in the following specific examples). The nonionic surfactants, of the Formula (1) may be used alone or as a plural mixture of them.
In the Formula (2), Rxe2x80x2 as a hydrophobic group, is an alkyl group, and the value of xxe2x80x2 representing the chain length of the alkyl group is from 4 to 12, preferably from 6 to 10. If xxe2x80x2 is too small, the PTFE aqueous dispersion composition tends to have a high surface tension, whereby the wettability tends to be low. Inversely, if xxe2x80x2 is too large, when the dispersion is left to stand for a long time, the fine particles of PTFE are likely to be sedimented, whereby the storage stability tends to be impaired.
Further, Axe2x80x2 which is a hydrophilic group, is a polyoxyethylene chain having from 5 to 20 oxyethylene groups. From 7 to 12 oxyethylene groups are particularly preferred from the viewpoint of the viscosity and the stability.
Specific examples of the nonionic surfactant of the Formula (2) include, for example, C9H19C6H4O(C2H4O)9-10H and C8H17C6H4O(C2H4O)9-10H. The nonionic surfactants of the Formula (2) may be used alone or as a plural mixture of them.
Among the nonionic surfactants of the Formulae (1) and (2) in the present invention, it is novel to use a compound of the Formula (3) as a nonionic surfactant in a PTFE aqueous dispersion composition. By the use of the nonionic surfactant of the Formula (3), it is possible to obtain a PTFE aqueous dispersion composition whereby foams formed by stirring are readily extinguishable, multi-coating is possible, and a sintered PTFE film is free from coloration.
In the Formula (3), B which is a hydrophilic group, is a polyoxyalkylene chain constituted by from 5 to 20 oxyethylene groups and from 1 to 2 oxypropylene groups, particularly preferably a polyoxyalkylene chain having from 7 to 12 oxyethylene groups and from 1 to 2 oxypropylene groups from the viewpoint of the viscosity and the stability.
In B, the oxypropylene groups may be present in the polyoxyethylene chain or may be bonded to the terminals of the polyoxyethylene chain. However, when they are bonded to the terminals of the polyoxyethylene chain, the defoaming property will be good, and particularly when they are bonded to the molecular terminal side of the two polyoxyethylene chain terminals, the defoaming property will be better, such being preferred.
When B contains no oxypropylene group, the defoaming property tends to be low. When oxypropylene groups are three or more, the surface tension tends to be high, and the wettability tends to be low, and at the time of multi-coating, xe2x80x9ccissingxe2x80x9d or xe2x80x9cpockmarksxe2x80x9d is likely to result.
Specific examples of the nonionic surfactant of the Formula (3) include, for example, surfactants having molecular structures such as C13H27O(C2H4O)8C3H6OH, C13H27O(C2H4O)9C3H6OH, C13H27O(C2H4O)10(C3H6O)2H, and C16H27(C2H4O)12(C3H6O)2H. The nonionic surfactants of the Formula (3) may be used alone or as a plural mixture of them.
Further, the molecular structure of the nonionic surfactant is a mixture of plural substances having a certain distribution, and the carbon number of the alkyl group in the nonionic surfactants and the numbers of the oxyethylene groups and the oxypropylene groups in the oxyalkylene group will be represented by average values. Each numerical value is not limited to an integer.
In the present invention, the nonionic surfactant to be used for improvement of the friction stability may be the nonionic surfactant of the Formula (1) alone, the nonionic surfactant of the Formula (2) alone or a combination of the nonionic surfactant of the Formula (1) and the nonionic surfactant of the Formula (2).
Further, in the present invention, when the nonionic surfactant represented by the Formula (1) is used, the effect for improvement of the friction stability is particularly remarkable.
Further, in the PTFE aqueous dispersion composition of the present invention, the content of the nonionic surfactant of the Formula (1), (2) or (3) is from 2 to 12 wt % based on the fine particles of PTFE. If it is smaller than this range, the fine particles of PTFE tends to agglomerate due to a mechanical stress such as stirring, whereby the stability tends to deteriorate. If the surfactant is incorporated in a large amount, such will be suitable for an application for thick coating, but if it is too much, the thermally decomposed gas of the surfactant will increase at the time of sintering, thus causing a bad odor, and microcracks are likely to form in the coated layer. Preferably, it is from 4 to 12 wt %.
In the present invention, a polyethylene oxide is employed as a friction stabilizer. The average molecular weight of the polyethylene oxide is within a range of from 100,000 to 2,000,000, preferably within a range of from 100,000 to 1,000,000. This polyethylene oxide can be obtained by polymerizing ethylene oxide, or by adjusting the molecular weight of such a polymer by applying a radiation, an electron ray, heat, a mechanical stress or other means to the polymer to suitably cause the main chain scission. Further, the polyethylene oxide may be one containing propylene oxide or other copolymer units in a degree not to impair the water-solubility.
If the average molecular weight is larger than the above range, so-called stringiness, a string-forming phenomenon of the aqueous dispersion, tends to occur, whereby processing tends to be difficult, and the viscosity reduction or the property change of the aqueous dispersion tends to be substantial, such being undesirable. And, if it is small, it tends to be difficult to obtain an adequate effect for friction stability.
The added amount of the polyethylene oxide is at least 0.01 wt % and less than 1 wt %, particularly preferably from 0.1 to 0.5 wt %, based on PTFE. If the added amount is too small, the friction stability tends to be low, and if it is too large, the thermal decomposition product at the time of sintering tends to be substantial, and the viscosity of the liquid tends to increase, such being undesirable.
Further, if the polyethylene oxide is added to the PTFE aqueous dispersion composition, so-called clusters are likely to form by inclusion of air during the dissolution. Accordingly, a method of preliminarily dissolving or dispersing it in water or in a water-soluble organic solvent such as isopropyl alcohol, propylene glycol, ethylene glycol or polyethylene glycol, and then adding it, may suitably be selected.
In the present invention, an association type thickener based on a water-soluble polyurethane is employed as a friction stabilizer. The association type thickener based on a water-soluble polyurethane is obtainable by reacting a polyisocyanate with a polyalkylene ether alcohol or by reacting a polyisocyanate with a polyalkylene ether polyol and a polyalkylene ether alcohol. It is one having at least two hydrophobic groups and a hydrophilic group made of a polyoxyalkylene composed mainly of oxyethylene groups with a polymerization degree of from 1 to 500. As its specific examples, JP-A-9-71766 and JP-A-9-71767 disclose compounds represented by the following molecular Formulae:
(wherein R1 is a m-valent hydrocarbon group, each of R2 and R4 which may be the same or different from each other, is an alkylene group, R3 is a (h+1)-valent hydrocarbon group which may have a urethane bond, R5 is a branched hydrocarbon group, m is a number of at least 2, h is a number of at least 1, each of k and n is a number of from 1 to 500, and R2 and R4 are preferably ethylene groups.)
(wherein R6 is a q-valent hydrocarbon group which may have a urethane bond, R is an alkylene group, R8 is a branched hydrocarbon group, p is a number of from 1 to 500, q is a number of at least 1, and R7 is preferably an ethylene group.)
Further, as a commercial product, Adecanol UH series (manufactured by Asahi Denka Kogyo K.K.), TAFIGEL PUR series (manufactured by MUNZING CHEMIE GMBH) or SN thickener 603, 604, 612 or 614 (manufactured by SUN-NOPCO K.K.) may, for example, be used.
The added amount of the association type thickener based on the water-soluble polyurethane is at least 0.01 wt % and less than 1 wt %, based on PTFE. It is particularly preferably from 0.1 to 0.5 wt %. If the added amount is too small, the effect for friction stabilization tends to be small, and if it is too large, the thermal decomposition product during sintering tends to be substantial, and the viscosity of the liquid tends to increase, such being undesirable.
The reason for the improvement of the friction stability of the PTFE aqueous dispersion composition by the addition of the above polyethylene oxide or the association type thickener based on the water-soluble polyurethane, is not clearly understood. It is conceivable that when a frictional stress or a shearing stress is exerted to the fine particles of PTFE, the particles will slip among themselves by the lubricating function of the stabilizer, whereby coagulation by contact of the PTFE particles one another will be prevented. It is considered that polyethylene glycols or other thickeners having relatively low molecular weights have low effects for improvement of the friction stability, since their lubricating functions are small. Further, among polymers of ethylene oxide, those having molecular weights of at most about 20,000, are usually called polyethylene glycols and are distinguished from those having larger molecular weights, which are called polyethylene oxides. The polyethylene oxide and the association type thickener based on the water-soluble polyurethane to be used as friction stabilizers, may be used in combination.
To the PTFE aqueous dispersion composition of the present invention, components such as fluorine type or silicone type nonionic surfactants, anionic surfactants, thixotropic agents, various salts, water-soluble organic solvents, antiseptics such as ammonia, various leveling agents, coloring agents, pigments, dyes or fillers, may be optionally added, as the case requires.
The viscosity of the PTFE aqueous dispersion composition of the present invention is preferably within a range of from 10 to 50 mPs as measured at 23xc2x0 C. If it is lower than this range, the PTFE particles are likely to sediment, whereby the standing stability tends to be impaired, and if it is higher than this range, the amount, applied at the time of coating, tends to be large, such being undesirable.
As a method for producing the PTFE aqueous dispersion composition of the present invention, a method may be mentioned wherein the nonionic surfactant of the Formula (1), (2) or (3) is added to the emulsion polymerization solution for primary stabilization, followed by concentration to a PTFE solid content of from 40 to 65 wt % by means of a known method such as an electrical concentration method or a phase separation method, and further by adjustment to a liquid physical properties suitable for various applications or for stabilization for storage for a long period of time, and if necessary, from 0.01 to 1 wt % of an antiseptic such as ammonia, a nonionic surfactant, a friction stabilizer, etc., are added to obtain an aqueous dispersion composition having a PTFE concentration of from 30 to 65 wt %.
The amount of the nonionic surfactant of the Formula (1), (2) or (3) added to the emulsion polymerization solution for primary stabilization, is preferably from 2 to 12 wt %, particularly preferably from 2 to 8 wt %, based on PTFE.
Now, the present invention will be described in further detail with reference to Examples and Comparative Examples, but these will by no means restrict the present invention.
Here, working Examples are Examples 1 to 5 and 12 to 14, and Comparative Examples are Examples 6 to 11 and 15.
A method for preparing a sample and an evaluation method of each item will be shown below.
(A) Surface tension: The surface tension of a PTFE aqueous dispersion composition was measured by a ring method using a platinum wire ring.
(B) Viscosity: The viscosity of a PTFE aqueous dispersion was measured by means of a Brookfield viscometer at a liquid temperature of 23xc2x0 C. using #1 spindle at 60 rpm.
(C) Friction stability: Using a tube type pump having a TYGON tube with an outer diameter of 7.9 mm and an inner diameter of 4.8 mm mounted, 100 cc of a PTFE aqueous dispersion composition in a 200 cc beaker was circulated for two hours at a liquid transporting amount of 200 cc per minute at room temperature of 23xc2x0 C., whereupon coagulates were collected by a 200 mesh nylon filter and the weight of the coagulates, dried at 120xc2x0 C. for one hour, was measured. Here, if the amount of the coagulates was 0.6 g or less, the stability was rated as good, and if it was 1 g or more, the stability was rated as poor.
(D) Thermal stability test: A PTFE aqueous dispersion composition was left to stand at 50xc2x0 C. for 200 hours while simply stirring up and down once per day, and the viscosity and the friction stability were measured.
(E) Stringiness: A PTFE aqueous dispersion composition was dropped by using a dropping pipette, and the presence or absence of stringing was visually determined.
(F) Standing stability: A PTFE aqueous dispersion composition was left to stand in a 100 ml measuring cylinder at room temperature for two months, whereupon the thickness of the formed supernatant layer and the thickness of the residue at the bottom were measured. If such values are not more than 10 mm upon expiration of two months, the composition can be used without any practical problem.
(G) Defoaming property: 100 ml of a PTFE aqueous dispersion composition was put into a 500 ml measuring cylinder, air was brown thereinto by means of a diffuser stone, and after the height of the foam became 200 mm, air was stopped, and the composition was left to stand naturally for 5 minutes, whereupon the height of the foam was measured.
(H) Thickness of PTFE film: Using an eddy-current thickness tester, the average value of measurements at 10 points and the standard deviation were measured.
(I) Tensile strength: Test specimens were punched out by a micro dumbbell, and a tensile test was carried out by means of an Instron type tensile tester at 23xc2x0 C. with a distance between chucks being 35 mm at a tensile speed of 100 mm/min. Five specimens are measured, and the average value of the tensile strength and the standard deviation were calculated. The degree of fluctuations of the tensile strength was judged in accordance with the following standards.
Large fluctuations: Standard deviation greater than 10(xc3x97106/m2 (hereinafter represented by MN/m2))
Small fluctuations: Standard deviation less than 5(MN/m2)
(J) Degree of coloration of e.g. a PTFE film, a glass fiber cloth or the like:
The object is placed on white paper and visually evaluated.
(K) Sedimentation stability: A PTFE aqueous dispersion composition was left to stand in a 100 ml measuring cylinder at room temperature for one month, whereupon good or not was judged on such a basis that formation of the supernatant and formation of the sedimented product at the bottom are remarkable or not.
Average molecular structures of surfactants used in the respective Examples are shown in Table 1. | {
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This invention relates to an energy saving system for controlling the temperature of buildings, particularly of animal raising establishments, comprising compartmentalized areas for a plurality of living animals, which system is also suitable for reducing the spread of infection between the individual compartments in said establishment.
It is known that the air in buildings which serve for containing a plurality of living animals contains waste products due to exhaled carbon dioxide and increased humidity. Added to these in animal storage structures are gases and vapors from decomposition of animal waste products, e.g. fecal matter and urine. The elimination of the vapors was made before exclusively through an exchange of air (by natural or artifical ventilation). The fresh air that was introduced had to be heated in the winter or during cold weather at other times of the year. The largest part of the heating energy is spent essentially for heating the incoming fresh air, whereas the heat content of the exhausted air is lost to the atmosphere.
Systems are known in which a heat exchange is carried out between the introduced and exhausted air, whereby an about 15-30% reduction in the energy required for heating is obtained. This method is, however, thermodynamically not sufficiently effective, since the heat exchange takes place at the lower temperature level of the exhausted air and more heat is required to raise the temperature of the incoming air to an acceptable level.
A known solution is described in Hungarian Pat. No. 174,791, according to which water vapor (steam) that is created in the building is removed through condensation, not by exhaust. The heat energy content of the water vapor (steam) amounts to about 2,350-2,500 kJ/kg. According to Hungarian Pat. No. 182,321, a heat pump is employed for the condensation and the heat content of the water vapor (steam) can be utilized at an effective temperature level with the aid of that pump. This system requires only an amount of fresh air which is required for removing the contaminating gases. In the case of poultry storage this amounts to, e.g. in the case of current norms for air exchange, a required quantity of fresh air of 2.5-4 cubic meter/kg live weight/hr in the winter, whereas the fresh air feed in the case of the water vapor condensation solution becomes lowered to 0.3-0.5 cubic meter/kg live weight/hr. According to experience a part of the contaminated gases condenses together with the water vapor (steam). It can be demonstrated that with such methods the required amount of primary energy can be lowered by about 60-75%, depending on the variety of animal. The water vapor condensation system is used in the summer to make the inside temperature tolerable by cooling, so that the production results can be maintained at optimum levels.
Further energy savings can be achieved when a suitable solution is found for the elimination of the decomposition gases or for reducing the proportion of such gases in the air of the area in question. Such method is described in Hungarian patent application No. 1228/84, according to which a substantial part of the contaminated exhaust gases is removed by chemical filtration. The water vapors obtained in that manner, contain a negligibly low amount of exhaust gas content, but have a heat content, can be recirculated into the area as pure air at a temperature of about 20-26 degrees Centigrade.
The amount of fresh air needed can be considerably reduced, but not entirely eliminated, by means of the aforementioned solutions. The ideal condition would be when only the oxygen requirement would have to be introduced from the outside. Even the reduced amount of air that is introduced into the area contains more oxygen than is necessary for the breathing of the animals.
Recently, in the case of raising and housing, economic considerations raise problems in addition to that of achieving energy savings. One such problem is that, due to the danger of infection, different age groups cannot be kept in the same growing plant so that the utilization of the plants becomes uneconomical.
The present invention aims at providing a solution to the aforementioned problems and to create a production system which, in addition to energy savings, realizes a better utilization of the plant space and a more economical organization of operations in which the raising of different age groups can be achieved in a single poultry raising plant, without any danger. | {
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Recently, the variety of so-called digital home appliances is growing. For example, a hard disk recorder, a digital versatile disk (DVD) recorder or a multiple function hard disk recorder and DVD recorder is available for use in recording television programs. Also, in addition to playing ordinary compact disks (CDs), various forms of music playing are now available such as reproducing compressed data recorded in various kinds of memory cards or a hard disk. | {
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This invention relates to the refining of hydrocarbons, and more particularly to the production of lubrication oils by catalytic hydrodewaxing.
In the production of lubricating oils, a petroleum refiner is often confronted with the problem of removing waxy paraffinic materials from hydrocarbon liquids which could otherwise be easily upgraded to lubricating oil base stocks and the like. The presence of the waxy paraffins is undesirable because they impart an unacceptably high pour point to the oil, thereby reducing the effectiveness of the oil under low temperature conditions.
The production of lubricating oils, therefore, often requires a process step for removing waxy paraffins, as for example by solvent dewaxing. Yet another method is catalytic dewaxing wherein the waxy feedstock, usually a waxy distillate obtained from a previous refining operation, is contacted with a suitable catalyst under conditions of elevated temperature and pressure so as to crack the waxy paraffins to other hydrocarbons having less effect upon the pour point. In general, the catalyst is highly selective for cracking the waxy components, and oftentimes the catalyst employed has hydrogenation activity such that, in the presence of hydrogen, the cracked components are essentially immediately saturated by hydrogenation. Dewaxing in this manner is usually referred to as "hydrodewaxing," and the catalyst employed is termed a hydrodewaxing catalyst.
Besides an acceptable pour point, the lubricating oil obtained from hydrodewaxing or other dewaxing operation must often meet or exceed established criteria, as for example, a specified viscosity index for the particular application in which the lubricating oil will find service. As a rule, the higher the viscosity index of a given lubricating oil, the more desirable it is, assuming that the viscosity index is increased without detrimentally affecting other desired properties of the oil.
Accordingly, it is a major object of the present invention to provide a novel catalytic hydrodewaxing process wherein a product lubricating oil of improved viscosity index is obtained without detrimentally affecting its other properties, as for example its pour point. It is yet another object of the invention to provide such a product in a high yield but with relatively low hydrogen consumption, even at relatively high operating temperatures. And it is a specific object of the invention to provide a novel hydrodewaxing process wherein the selectivity for an improved lubricating oil product is high, despite a relatively high operating temperature. These and other objects of the invention will become more apparent in view of the following description of the invention. | {
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The exemplary embodiments of the present invention relate to a liquid crystal display device and a projection display apparatus.
Liquid crystal display devices are used as optical modulation devices of projection display apparatuses, such as a liquid crystal projector. In the liquid crystal display devices, a liquid crystal layer is interposed between a pair of substrates. An electrode to apply an electric field to the liquid crystal layer is formed inside the pair of substrates. An alignment film to control an alignment state of liquid crystal molecules is formed inside the electrode. Image light is formed on the basis of variation in the alignment of the liquid crystal molecules at the time of applying a non-selection voltage and at the time of applying a selection voltage.
In the projection display apparatus employing the related art liquid crystal display device, the contrast ratio of a projected image is at most 1:500, which is still smaller than the contrast ratio of 1:3000 in the projection display apparatus employing a mechanical shutter such as DLP (registered trade mark) technology using DMD (digital micromirror device). This results from a viewing angle characteristic of the liquid crystal display device. Originally, the source light which enters the optical modulation device of the projection display apparatus is not a complete parallel light. Since the liquid crystal display device used as the optical modulation device has an entry-angle dependency, this causes reduction of the contrast ratio of the projected image.
Therefore, in order to compensate for the entry-angle dependency of the liquid crystal display device, an optical compensating plate is employed. The optical compensating plate hybrid-aligns discotic liquid crystal molecules showing a negative birefringence (see, for example, Japanese Unexamined Patent Application Publication No. H8-50206 and “Introduction Lecture 11 for Liquid Crystal Display: Viewing-angle Enlargement Technique of TFT-LCD with Discotic Optical Compensating plate”, Liquid Crystal, Japan Liquid Crystal Society, Vol. 6, No. 1, p 84-92, Jan. 25, 2002, by Hiroyuki Mori). As seen in the normal direction, the optical compensating plate has a fast axis and a slow axis due to the hybrid alignment. Accordingly, the optical compensating plate has a phase retardation in the normal direction.
FIG. 13 is a graph illustrating a viewing-angle dependency of the phase retardation in the optical compensating plate described in Japanese Unexamined Patent Application Publication No. H8-50206. It can be seen from FIG. 13 that the phase retardation when the viewing angle to the optical compensating plate is 0°, that is, the phase retardation in the normal direction of the optical compensating plate, is about 40 nm. Examples where the phase retardation in the normal direction of the optical compensating plate is 70 nm and 80 nm are disclosed in Japanese Unexamined Patent Application Publication No. H9-15587.
In addition, a first optical compensating plate is disposed at the outside of the substrate at the light-entry side in the liquid crystal panel and a second optical compensating plate is disposed at the outside of the substrate at the light-exit side. The first optical compensating plate and the second optical compensating plate are disposed such that the fast axis direction (that is, the X axis direction which is an alignment control direction of the discotic liquid crystal and is indicated by Arrow 71 in FIG. 5 which shows an exemplary embodiment of the invention) as seen in the normal direction of the respective optical compensating plates is approximately equal to the alignment control direction of the alignment film in the corresponding substrate. Since the alignment control directions of the respective substrates in the liquid crystal panel are approximately perpendicular to each other, the alignment control directions of the optical compensating plates are approximately perpendicular to each other. | {
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The present application is related to a co-pending application entitled METHOD AND SYSTEM FOR INTERRUPT HANDLING USING DEVICE PIPELINED PACKET TRANSFERS, Application Ser. No. 09/224,111, filed on even date herewith and xe2x80x9cPIPELINED READ TRANSFERSxe2x80x9d, previously filed and now issued as U.S. Pat. No. 6,240,474 on May 29, 2001, both application and patent assigned to the assignee of the present application.
1. Technical Field
The present invention relates generally to information processing systems and more particularly to an improved information transfer methodology in a computer-related environment. Still more particularly, the present invention relates to a method and system for input/output device read transfers that utilize a request phase and a response phase in association with the systems interrupt controller.
2. Description of the Related Art
As computer systems and networked computer systems proliferate, and become integrated into more and more information processing systems which are vital to businesses and industries, there is an increasing need for faster information processing and increased data handling capacity. Even with the relatively rapid state-of-the-art advances in processor technology, and the resulting increased processor speeds, a need still exists for faster processors and increased system speeds and more efficient information processing methodologies. This need is at least partially due to a growing number of computer applications and capabilities, including extensive network and rich graphics and display applications among others. As new applications for computers are implemented, new programs are developed and those programs are enriched with new capabilities almost on a daily basis. While such rapid development is highly desirable, there is a capability cost in terms of system speed.
One of the problems that have been difficult to solve with the rapid growth of computer data or information-processing systems is the complexity of interrupts from I/O devices. There are a number of problems that need to be solved simultaneously relative to interrupts, more specifically, scalability, data coherency, latency and how to connect far removed remote input/output devices. In terms of scalability, the problem is in how to scale from a small number of devices to a large number without incurring larger than necessary costs at the low end or limiting the number of interrupting devices at the high end. The problem encountered in data coherency is how to assure that the interrupt is not serviced by the system before the data is at its destination. In today""s computer systems, the I/O device transfers the data through host bridges and the like and signals that the operation is complete through a separate path. If this separate path is faster than the path that the data takes, then the interrupt could be serviced before the data is at the destination, and wrong data could be accessed.
The problem inherent in latency is how to reduce the service time and overhead of a device interrupt. If the latency to access the I/O device to gather status or reset interrupts is large, then the interrupt service time is extended, affecting the amount of useful work that the system can perform. Lastly, with respect to remote input/output (I/O) devices, a problem exists is how to interconnect the interrupts from I/O devices that may be located across cables or fiber optic links (a very real possibility because all the I/O in large systems may not fit inside a relatively small box).
Running separate wires from each I/O device to some centrally located interrupt controller may not be feasible.
In the past, there have been a number of attempts to solve some of these problems individually.
Therefore, there is a need for an improved information processing methodology and system in which information is more efficiently transferred between master and target devices during information processing transactions and which offers a global solution to all the problems stated above. This invention solves these problems in a novel and unique manner that has not been part of the art previously.
It is therefore one object of the present invention to provide a method and system for scaling from a small number of devices to a large number without incurring larger than necessary costs at the low end or limiting the number of interrupting devices at the high end.
It is another object of the present invention to provide a method and system in which information is more efficiently transferred by increasing data coherency and reducing latency between master and target devices during information processing transactions.
It is still yet another object of the present invention to provide a method and system in which interrupts can be may be transferred from a remotely attached I/O device.
The foregoing objects are achieved as is now described. A method and apparatus is provided in which Pipelined Packet Transfers (PPT) are implemented. The PPT methodology includes a request phase and a response phase. The PPT request phase involves a PPT request master delivering to a PPT request target a source address, a destination address and an information packet for the interrupt being requested. The PPT response phase involves the PPT request target becoming a PPT response master with the PPT response master delivering to a PPT request master a destination address and a data packet which includes the interrupt processing information. Pipelined Packet transfers (PPT) are ordered in accordance with a predetermined processing priority to improve performance and avoid deadlock.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description. | {
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In FIG. 1, a prior art example of a dedicated boundary scan path or register exists around a master circuit 102, a slave 1 circuit 104, and a slave 2 circuit 106. The master circuit, such as a DSP, CPU, or micro-controller, is a circuit that controls the slaves. The slave circuits are circuits being controlled by the master, such as RAM, ROM, cache, A/D, D/A, serial communication circuits, or I/O circuits. The master and slave circuits could exist as individual intellectual property core sub-circuits inside an integrated circuit or IC, or as individual ICs assembled on a printed circuit board or multi-chip module (MCM). The scan paths 108-112 around each circuit are connected together serially and to a test data input (TDI) 114, which supplies test data to the scan paths, and a test data output (TDO) 116, which retrieves data from the scan paths.
For simplification, only a portion of the scan paths 108-112 of each circuit is shown. The scan paths of FIG. 1 are designed using dedicated scan cells, indicated by capital letters (C) and (D) in circles. The word dedicated means that the cell's circuitry is used for testing purposes and is not shared for functional purposes. The scan cells are located between the internal circuitry and the input buffers 128 and output buffers 130 of the slaves and master circuit.
In FIG. 2, an example of a dedicated scan cell consists of multiplexer 1 (MX1) 202, memory 1 (M1) 204, memory 2 (M2) 206, and multiplexer 1 (MX2) 208. This scan cell is similar to scan cells described in IEEE standard 1149.1, so only a brief description will be provided. During operation in a functional mode, functional data passes from the functional data input (FDI) 212 to the functional data output (FDO) 214. In a functional mode, control inputs 210 to the scan cell can: (1) cause FDI data to be loaded into M1 via MX1 during a capture operation; (2) scan data from TDI 216 through MX1 and M1 to TDO 218 during a shift operation; and (3) cause data in M1 to be loaded into M2 during an update operation. Neither the capture, shift, nor update operation disturbs the functional data passing between FDI and FDO. Thus the scan cell of FIG. 2 can be accessed and pre-loaded with test data while the cell is in functional mode. The data scan cell (D) associated with the D31 output of slave 1 104 has connections corresponding to the FDI 212, TDI 216, FDO 214, and TDO 218 signal connections of the FIG. 2 scan cell.
During a functional mode of operation of the circuit in FIG. 1, data is transferred from one of the slaves to the master via a 32-bit data bus (D0-31), indicated by the wired bus connections 126. In a functional mode the scan cells are transparent, allowing functional control and data signals to pass freely through the cells. In this example, the master enables slave 1 to transfer data by the ENA1 control signal, which is output from the master to slave 1. Likewise the master enables slave 2 to transfer data by the ENA2 control signal, which is output from the master to slave 2. While only two slave circuits are shown, any number could be similarly connected to and operated by the master. Since all the scan cells of the scan paths 108-112 are dedicated for test, they can be scanned from TDI to TDO without disturbing the functional mode of the FIG. 1 circuit
As mentioned, being able to scan data into the scan paths during functional mode allows pre-loading an initial test pattern into the scan paths. The initial test pattern establishes both a data test pattern in the data scan cells (D) and a control test pattern in the control scan cells (C). By pre-loading an initial test pattern into the scan paths, the circuits can safely transition from a functioning mode to a test mode without concern over bus contention between the slave circuit's data busses. For example, the ENA1 122 and ENA2 124 control scan cells (C) can be pre-loaded with control data to insure that only one of the slave's D0-31 data busses is enabled to drive the wired bus connection 126. Maintaining output drive on one of the slave data busses upon entry into test mode prevents the wired data bus 126 from entering into a floating. (i.e. 3-state) condition. Preventing bus 126 from floating is desirable since a floating input to input buffers 128 of master 102 could cause a high current condition.
When test mode is entered, functional operation of the master and slave circuits stop and the scan cells in the scan paths take control of the master and slave circuit's data and control signal paths. A data scan cell (D) exists on each of the 32-bit data signal paths of each circuit 102-106, and a control scan cell (C) exists on each of the ENA1 and ENA2 control paths of each circuit 102-106. Having dedicated data and control scan cells located as shown in FIG. 1, enables safe test entry and easy interconnect testing of the wiring between the master and slave circuits when the scan paths are placed in test mode. During interconnect test mode, a capture, shift, and update control sequence, such as that defined in IEEE standard 1149.1, can be used to control the scan paths.
To prevent contention between slave 1 and slave 2 data outputs 126 during the capture, shift, and update control sequence, the 3-state control outputs 118-120 of the ENA1 and ENA2 control scan cells 122-124 do not ripple during the capture and shift part of the control input sequence. This is accomplished by having the data in M2 of FIG. 2 be output, via MX2, during the capture and shift operation. Only during the update part of the control input sequence are the outputs 118-120 of the control scan cells 122-124 allowed to change state by new data being loaded into M2. Similarly, the outputs from the data scan cells (D) do not ripple during capture and shift operations, but rather change state only during the update part of the control input sequence.
In FIG. 3, a prior art example of a shared boundary scan path exists around a master 302 and slave circuits 304-306. As in FIG. 1, the scan paths 308-312 around each circuit are connected together serially and to a test data input (TDI), which supplies test data to the scan paths, and a test data output (TDO), which retrieves data from the scan paths. The scan paths of FIG. 3 are designed using shared scan cells (C) and (D), i.e. the scan cell memory is shared for both test and functional purposes. As an aid to indicate use of shared scan cells as opposed to dedicated scan cells, the shared scan cells of FIG. 3 and subsequent figures are shown positioned outside the boundary scan paths 308-312 and in the functional circuits. The dedicated scan cells of FIG. 1 were shown positioned inside the boundary scan paths 108-112. Again, for simplification, only a portion of each circuit's boundary scan path is shown.
In FIG. 4, an example of a conventional shared scan cell consists of a multiplexer (MX) 402 and a memory (M) 404. During a functional mode of operation, control inputs 406 form a path between FDI 408 and the data input of M 404 via MX 402, to allow functional data to be clocked from FDI to FDO 410. During a test mode, the control inputs 406 cause FDI data to be clocked into M via MX during a capture operation, and cause test data to be clocked from TDI 412 to TDO 414 during a shift operation. Since M 404 is used functionally, it cannot be accessed and pre-loaded with test data as can the scan cell of FIG. 2. Thus the ability to access and pre-load test data while the master and slave circuits of FIG. 3 operate functionally is one of the key distinctions between dedicated (FIG. 2) and shared (FIG. 4) scan cells.
In FIG. 3, the data scan cell associated with the D31 output of slave 1 304 is labeled to indicate the FDI 408, TDI 412, FDO 410, and TDO 414 signal connections of the FIG. 4 scan cell.
During the functional mode of the circuit in FIG. 3, as in FIG. 1, data is transferred from one of the slaves to the master via the 32-bit data bus (D0-31) through shared connections 326. The master enables data transfer from slave 1 or slave 2 via the ENA1 and ENA2 control signals, respectively. Since the scan cells of the scan paths are shared and used functionally, they cannot be scanned from TDI to TDO without disturbing the functional mode of the circuits. Not being able to scan data into the scan paths during functional mode prevents pre-loading an initial test pattern into the scan paths.
By not being able to pre-load an initial test pattern into the scan paths, the slave circuits are put at risk of not safely transitioning into the test mode from the functional mode. This situation occurs due to the timing domains of the functional and test modes not being synchronous to one another, which results in asynchronous functional to test mode switching.
For example, if the circuits of FIG. 3 switched from the functional mode timing domain to a test mode timing domain, a possibility exists that the D0-31 output buffers of slave 1 and 2 could both be enabled as a result of an asynchronous mode switch that caused scan cell ENA1 322 and scan cell ENA2 324 to both output enable conditions on wires 318 and 320. This would force a voltage contention situation between slave 1 and 2, resulting in the output buffers being damaged or destroyed. This voltage contention situation does not occur in the boundary scan path of FIG. 1 since an initial safe test pattern is pre-loaded into the scan cells prior to the functional to test mode switching step.
Once in a test mode, the scan path of FIG. 3 can be accessed to shift in test data. During shift operations the outputs 318-320 of the control scan cells 322-324 ripple as data shifts through the cells. This output ripple from the control scan cells can cause the D0-31 output buffers of the slaves to be enabled and disabled during the shift operation. This control output ripple causes the output buffers of slaves 1 and 2 to be simultaneously enabled, again creating bus contention between the slaves. This voltage contention situation does not occur in the boundary scan path of FIG. 1 since M 206 maintains a safe control output via MX 208, during shift operations.
In FIG. 5, one prior art technique prevents the above-mentioned two voltage contention situations. The technique is based on providing additional circuitry and control inputs to enable or disable the slave's output buffers during test mode entry and again during each test mode shift operation. A signal gating circuit 528 is inserted into signal path 518 of slave 504 and a signal gating circuit 530 is inserted into signal path 520 of slave 506. A control signal C1 532 is added as an input to circuits 528 and 530. When C1 is in a first state, the ENA1 and ENA2 outputs from scan cells 522 and 524 are allowed to pass through circuits 528 and 530 to enable or disable the output buffers of slaves 504 and 506. However, when C1 is in a second state, the outputs of circuits 528 and 530 are forced, independent of ENA1 and ENA2, to disable the output buffers of slaves 504 and 506. By controlling C1 to the second state during the transition from functional mode to test mode, the first above mentioned voltage contention situation can be avoided. By again controlling C1 to the second state during each shift operation that occurs during test mode, the second above mentioned voltage contention situation can be avoided.
While the technique described above solves the voltage contention situations, it does so by introducing a floating (i.e. 3-state) condition on data bus 526. As described above, the output buffers of slaves 504 and 506 are disabled during test mode entry and during each shift operation. With the output buffers disabled, data bus 526 is not driven and may float to a voltage level that could turn on both input transistors of the input buffers of master 502. This could result in a low impedance path between the master's supply and ground voltages, potentially damaging or destroying the input buffers of master 502. | {
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1. Field of the Invention
The invention relates to a reduction vessel for the reduction of metal-oxide-bearing material, particularly of iron ore, by means of a reduction gas flowing countercurrently to the metal-oxide-bearing material, which reduction vessel is provided with an inlet for the metal-oxide-bearing material, an inlet for the reduction gas, an outlet for off-gas and an outlet for reduced material, downstream of which outlet a lower sealing leg is connected, a supply line for a first sealing gas being provided at the lower sealing leg in order to seal the reduction vessel against the environment. The invention further relates to a process for sealing a reduction vessel for the reduction of metal-oxide-bearing material, particularly of iron ore.
2. Description of the Related Art
Arrangements for sealing a reduction vessel against the environment are known (Direct from Midrex, Vol. 14, No. 3, 3rd quarter of 1989).
According to DE-A-34 32 090, sulfur-bearing ore is reduced in a shaft furnace in counterflow with reduction gas. The off-gas exiting the furnace is divided into two flows, the first flow being used for preheating and desulfurization of the ore which is located in a ore bin above the shaft furnace and the second flow being fed to a catalytic gas converter together with hydrocarbons in order to generate reduction gas.
Above the ore bin of the arrangement described in DE-A-34 32 090, a container is located from which ore is charged into the ore bin. Inert gas is injected into the connection between this container and the ore bin in order to prevent sulfur-bearing off-gas from exiting the ore bin through this connection. This measure thus serves to establish a gas seal.
An arrangement for cooling a gas-permeable bed of subsiding solid particles, for example, of reduced ore pellets, at the outlet of a reduction shaft furnace is known from AT-B-328 481.
Arrangements of this type are also known from DE-C-26 51 309 and U.S. Pat. No. 4,046,557. In these known arrangements, partly off-gas (waste reduction gas) from the reduction shaft furnace is used for cooling. These documents do not give any statements about the sealing of the reduction shaft furnace against the environment in order to prevent the gas contained in the reduction shaft furnace from exiting.
U.S. Pat. No. 4,212,452 describes a plant in which iron oxide is reduced to sponge iron in a shaft furnace through the addition of solid carbon-bearing material, which is gasified in an upper zone of the shaft furnace, and through the addition of reduction gas containing CO and H.sub.2 in a central zone of the shaft furnace. The iron oxide, together with the solid carbon-bearing material, is charged from the top into the shaft furnace and flows through the shaft furnace from the top to the bottom, partly cocurrently and partly countercurrently to the reduction gases. In a lower zone of the shaft furnace, the sponge iron formed by reduction is cooled with cool, dry reduction gas. The shaft furnace is sealed towards the top and bottom with one CO.sub.2 -operated gas seal each in order to prevent the undesirable escape of reduction gas from the shaft furnace, CO.sub.2 being recovered therein from waste reduction gas through gas scrubbing. This known arrangement has the disadvantage that the sealing gas, CO.sub.2, may enter the shaft furnace, which is undesirable with regard to reduction.
An arrangement which is used, for example, for the direct reduction of iron-oxide-bearing material by means of reduction gas in a shaft furnace is known from U.S. Pat. No. 3,850,616. The iron-oxide-bearing material flows through the shaft furnace from the top to the bottom countercurrently to the reduction gas and is cooled with cool reduction gas in the lower zone of the shaft furnace. In order to prevent reduction gas from exiting the shaft furnace, a gas seal operated with inert gas is provided at the lower end of the shaft furnace. This known arrangement has the disadvantage of high consumption of expensive inert gas.
Processes in which iron-oxide-bearing material is reduced in a shaft furnace by means of reduction gas and melted in a melting unit which is structurally connected with the shaft furnace are known from U.S. Pat. No. 4,248,626 and U.S. Pat. No. 4,270,740. In the melting unit, reduction gas is generated by coal gasification.
The reduction gas is withdrawn from the melting unit and cooled before it is charged into the shaft furnace in order to prevent the material reduced in the shaft furnace from agglomerating. In order to prevent the very hot reduction gas from being carried over from the melting unit directly into the shaft furnace, a gas seal is provided in the direct connection between the melting unit and the shaft furnace.
The applicant knows that gas seals operated with nitrogen, which seal shaft furnaces against the environment, are customary. Gas seals of this type have the disadvantage that the generation of nitrogen involves high technical expenditure, which results in high costs because large amounts of nitrogen are consumed. | {
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In robotically-assisted or telerobotic surgery, the surgeon typically operates a master controller to remotely control the motion of surgical instruments at the surgical site from a location that may be remote from the patient (e.g., across the operating room, in a different room or a completely different building from the patient). The master controller usually includes one or more hand input devices, such as joysticks, exoskeletal gloves or the like, which are coupled to the surgical instruments with servo motors for articulating the instruments at the surgical site. The servo motors are typically part of an electromechanical device or surgical manipulator (“the slave”) that supports and controls the surgical instruments that have been introduced directly into an open surgical site or through trocar sleeves into a body cavity, such as the patient's abdomen. During the operation, the surgical manipulator provides mechanical articulation and control of a variety of surgical instruments, such as tissue graspers, needle drivers, electrosurgical cautery probes, etc., that each perform various functions for the surgeon, e.g., holding or driving a needle, grasping a blood vessel, or dissecting, cauterizing or coagulating tissue.
This new method of performing telerobotic surgery through remote manipulation has, of course, created many new challenges. One such challenge results from the fact that a portion of the electromechanical surgical manipulator will be in direct contact with the surgical instruments, and will also be positioned adjacent the operation site. Accordingly, the surgical manipulator may become contaminated during surgery and is typically disposed of or sterilized between operations. From a cost perspective, it would be preferable to sterilize the device. However, the servo motors, sensors, encoders, and electrical connections that are necessary to robotically control the motors typically cannot be sterilized using conventional methods, e.g., steam, heat and pressure, or chemicals, because the system parts would be damaged or destroyed in the sterilization process.
A sterile drape has been previously used to cover the surgical manipulator and has included holes through which an adaptor (for example a wrist unit adaptor or a cannula adaptor) would enter the sterile field. However, this disadvantageously requires detachment and sterilization of the adaptors after each procedure and also causes a greater likelihood of contamination through the holes in the drape.
Yet another challenge with telerobotic surgery systems is that a surgeon will typically employ a large number of different surgical instruments/tools during a procedure. Since the number of manipulator arms are limited due to space constraints and cost, many of these surgical instruments will be attached and detached from the same manipulator arm a number of times during an operation. In laparoscopic procedures, for example, the number of entry ports into the patient's abdomen is generally limited during the operation because of space constraints as well as a desire to avoid unnecessary incisions in the patient. Thus, a number of different surgical instruments will typically be introduced through the same trocar sleeve during the operation. Likewise, in open surgery, there is typically not enough room around the surgical site to position more than one or two surgical manipulators, and so the surgeon's assistant will be compelled to frequently remove instruments from the manipulator arm and exchange them with other surgical tools.
What is needed, therefore, are improved telerobotic systems and methods for remotely controlling surgical instruments at a surgical site on a patient. In particular, these systems and methods should be configured to minimize the need for sterilization to improve cost efficiency while also protecting the system and the surgical patient. In addition, these systems and methods should be designed to minimize instrument exchange time and difficulty during the surgical procedure 316 Accordingly, a sterile adaptor and a system for robotic surgery having improved efficiency and cost-effectiveness is highly desirable. | {
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An example of conventional hologram recording method is disclosed in Patent Document 1. The method disclosed in this document is a technique where a recording beam is applied vertically to a hologram recording medium while a reference beam is applied to the illumination site of the recording beam with its incident angles varied under control of the tilt of a multiplex mirror. The multiplex mirror is supported by a supporting member and is tilted so as to pivot around a point where it is supported. The supporting member is movable in parallel to the hologram recording medium. The incident angle of the reference beam with respect to the hologram recording medium is changed in accordance with the tilt of the multiplex mirror, and then the multiplex mirror is moved in parallel to the hologram recording medium for directing the reference beam to the illumination site. Thus, the interference of the recording beam and the reference beam at the illumination site produces multiplex recording of holograms in accordance with the cross angle between these beams.
Patent Document 1: JP-A-2005-234145
With the above-described conventional hologram recording method, the tilt of the multiplex mirror needs to be controlled for varying the incident angle of the reference beam, and also the parallel movement of the multiplex mirror with respect to the hologram recording medium needs to be controlled for keeping the reference beam directed to the illumination site. Unfavorably, such control tends to be very complicated and difficult. | {
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The rapid transfer of important digital data including facsimilie, as well as analog information such as television pictures is becoming increasingly a part of business administration. Business establishments remain competitive by their ability to rapidly transfer sales and customer information between centers over nationwide or global communications links. The importance of preventing competitors from intercepting and using discreet or confidential information such as customer names and addresses or new product development information is increasingly important. Therefore, secure communications that can be interpreted only by authorized users is required to be more complex than the simple scrambling systems and algorithms of the past. A communications system that provides the greatest number of cryptographic algorithms for security coding of the information signal is required for highly competitive global commerce. It is presently possible to intercept signals radiated on a single carrier frequency and a single polarization by computer analysis of the signal. Splitting the information signal into segments for radiation on a plurality of carrier frequencies and polarizations increases the difficulty of intercepting the information in proportion to the number of frequencies and/or polarizations; i.e., the number of channels. This difficulty is further increased by further encoding each channel by well known aerospace coding methods. Enhancement of the signal by error detection and correction are also possible when the channel is encoded. By using a signal channel composed of a plurality of frequencies and/or polarizations, a receiver that sums the discrete signals to provide a signal power gain and provides extended information decoding capabilities, can be used. | {
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1. Technical Field
The present invention relates in general to container apparatus and, in particular, to a container apparatus that dispenses items, such as edible treats. Still more particularly, the present invention is related to a closure for a container apparatus.
2. Description of the Related Art
It is well known in the art that boredom is a significant contributor to destructive behavior in domesticated animals. For example, U.S. Pat. No. 6,634,318 to Rucker and the prior art referenced therein disclose that barking, digging and other destructive behaviors are common problem behaviors of canines that become discontented or bored. As further disclosed in these patents, one common approach utilized in the art to address such destructive behaviors in dogs is to provide a toy that dispenses food (e.g., treats) from its hollow interior cavity through a hole as a dog interacts with the toy.
U.S. Pat. No. 6,634,318 to Rucker further discloses the use of an edible plug to seal the hole through which the treats are dispensed from the interior cavity of the toy so that the treats do not prematurely spill out of the hole and the duration of a dog's interaction with the toy is extended. Rucker specifically teaches that it is desirable that the edible plug should be designed to be readily dislodged by the dog. Consequently, Rucker's plug is designed with a conic or cylindrical section and, when installed, has a larger diameter portion external to the toy and a smaller diameter portion inside the toy. This design permits the dog to easily remove the plug from the toy using its teeth, either by shearing the larger diameter portion from the smaller diameter portion or by pulling the plug out of hole. | {
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N/A
The present invention relates to the delivery of desired compounds (e.g., drugs and nucleic acids) into cells using pH-sensitive delivery systems. The present invention provides compositions and methods for the delivery and release of a compound of interest to a cell.
Drug Delivery
A variety of methods and routes of administration have been developed to deliver pharmaceuticals that include small molecular drugs and biologically active compounds such as peptides, hormones, proteins, and enzymes to their site of action. Parenteral routes of administration include intravascular (intravenous, intraarterial), intramuscular, intraparenchymal, intradermal, subdermal, subcutaneous, intratumor, intraperitoneal, and intralymphatic injections that use a syringe and a needle or catheter. The blood circulatory system provides systemic spread of the pharmaceutical. Polyethylene glycol and other hydrophilic polymers have provided protection of the pharmaceutical in the blood stream by preventing its interaction with blood components and to increase the circulatory time of the pharmaceutical by preventing opsonization, phagocytosis and uptake by the reticuloendothelial system. For example, the enzyme adenosine deaminase has been covalently modified with polyethylene glycol to increase the circulatory time and persistence of this enzyme in the treatment of patients with adenosine deaminase deficiency.
The controlled release of pharmaceuticals after their administration is under intensive development. Pharmaceuticals have also been complexed with a variety of biologically-labile polymers to delay their release from depots. These polymers have included copolymers of poly(lactic/glycolic acid) (PLGA) (Jain, R. et al. Drug Dev. Ind. Pharm. 24, 703-727 (1998), ethylvinyl acetate/polyvinyl alcohol (Metrikin, D C and Anand, R, Curr Opin Ophthalmol 5, 21-29, 1994) as typical examples of biodegradable and non-degradable sustained release systems respectively.
Transdermal routes of administration have been effected by patches and ionotophoresis. Other epithelial routes include oral, nasal, respiratory, and vaginal routes of administration. These routes have attracted particular interest for the delivery of peptides, proteins, hormones, and cytokines, which are typically administered by parenteral routes using needles. For example, the delivery of insulin via respiratory, oral, or nasal routes would be very attractive for patients with diabetes mellitus. For oral routes, the acidity of the stomach (pH less than 2) is avoided for pH-sensitive compounds by concealing peptidase-sensitive polypaptides inside pH-sensitive hydrogel matrix (copolymers of polyethyleneglycol and polyacrylic acid). After passing low pH compartments of gastrointestinal tract such structures swells at higher pH releasing thus a bioactive compound (Lowman A M et al. J. Pharm. Sci. 88, 933-937 (1999). Capsules have also been developed that release their contents within the small intestine based upon pH-dependent solubility of a polymer. Copolymers of polymethacrylic acid (Eudragit S, Rohm America) are known as polymers which are insoluble at lower pH but readily solubilized at higher pH, so they are used as enteric coatings (Z Hu et al. J. Drug Target., 7, 223, 1999).
Biologically active molecules may be assisted by a reversible formation of covalent bonds. Quite often, it is found that the drug administered to a patient is not the active form of the drug, but is what is a called a prodrug that changes into the actual biologically active compound upon interactions with specific enzymes inside the body. In particular, anticancer drugs are quite toxic and are administered as prodrugs which do not become active until they come in contact with the cancerous cell (Sezaki, II., Takakura, Y., Hashida, M. Adv. Drug. Delivery Reviews 3, 193, 1989).
Recent studies have found that pH in solid tumors is 0.5 to 1 units lower than in normal tissue (Gerweck L E et al. Cancer Res. 56, 1194 (1996). Hence, the use of pH-sensitive polymers for tumor targeting is justified. However, this approach was demonstrated only in vitro (Berton, M, Eur. J. Pharm. Biopharm. 47, 119-23, 1999).
Liposomes were also used as drug delivery vehicles for low molecular weight drugs and macromolecules such as amphotericin B for systemic fungal infections and candidiasis. Inclusion of anti-cancer drugs such as adriamycin have been developed to increase their delivery to tumors and reduce it to other tissue sites (e.g. heart) thereby decreasing their toxicity. pH-sensitive polymers have been used in conjunction with liposomes for the triggered release of an encapsulated drug. For example, hydrophobically-modified N-isopropylacrylamide-methacrylic acid copolymer can render regular egg phosphatidyl chloline liposomes pH-sensitive by pH-dependent interaction of grafted aliphatic chains with lipid bilayer (O Meyer et al., FEBS Lett., 421, 61, 1998).
Gene and Nucleic Acid-Based Delivery
Gene or polynucleotide transfer is the cardinal process of gene therapy. The gene needs to be transferred across the cell membrane and enter the nucleus where the gene can be expressed. Gene transfer methods currently being explored included viral vectors and physical-chemical methods.
Viruses have evolved over millions of year to transfer their genes into mammalian cells. Viruses can be modified to carry a desired gene and become a xe2x80x9cvectorxe2x80x9d for gene therapy. Using standard recombinant techniques, the harmful or superfluous viral genes can be removed and replaced with the desired normal gene. This was first accomplished with mouse retroviruses. The development of retroviral vectors were the catalyst that promoted current gene therapy efforts. However, they cannot infect all cell types very efficiently, especially in vivo. Other viral vectors based on Herpes virus are being developed to enable more efficient gene transfer into brain cells. Adenoviral and adenoassociated vectors are being developed to infect lung and other cells.
Besides using viral vectors, it is possible to directly transfer genes into mammalian cells. Usually, the desired gene is placed within bacterial plasmid DNA along with a mammalian promoter, enhancer, and other sequences that enable the gene to be expressed in mammalian cells. Several milligrams of the plasmid DNA containing all these sequences can be prepared and purified from the bacterial cultures. The plasmid DNA containing the desired gene can be incorporated into lipid vesicles (liposomes including cationic lipids such as Lipofectin) that then transfer the plasmid DNA into the target cell. Plasmid DNA can also be complexed with proteins that target the plasmid DNA to specific tissues just as certain proteins are taken up (endocytosed) by specific cells. Also, plasmid DNA can be complexed with polymers such as polylysine and polyethylenimine. Another plasmid-based technique involves xe2x80x9cshootingxe2x80x9d the plasmid DNA on small gold beads into the cell using a xe2x80x9cgunxe2x80x9d. Finally, muscle cells in vivo have the unusual ability to take up and express plasmid DNA.
Gene therapy approaches can be classified into direct and indirect methods. Some of these gene transfer methods are most effective when directly injected into a tissue space. Direct methods using many of the above gene transfer techniques are being used to target tumors, muscle, liver, lung, and brain. Other methods are most effective when applied to cells or tissues that have been removed from the body and the genetically-modified cells are then transplanted back into the body. Indirect approaches in conjunction with retroviral vectors are being developed to transfer genes into bone marrow cells, lymphocytes, hepatocytes, myoblasts and skin cells.
Gene Therapy and Nucleic Acid-Based Therapies
Gene therapy promises to be a revolutionary advance in the treatment of disease. It is a fundamentally new approach for treating disease that is different from the conventional surgical and pharmaceutical therapies. Conceptually, gene therapy is a relatively simple approach. If someone has a defective gene, then gene therapy would fix the defective gene. The disease state would be modified by manipulating genes instead of their products, i.e. proteins, enzymes, enzyme substrates and enzyme products. Although, the initial motivation for gene therapy was the treatment of genetic disorders, it is becoming increasingly apparent that gene therapy will be useful for the treatment of a broad range of acquired diseases such as cancer, infectious disorders (AIDS), heart disease, arthritis, and neurodegenerative disorders (Parkinson""s and Alzheimer""s).
Gene therapy promises to take full-advantage of the major advances brought about by molecular biology. While, biochemistry is mainly concerned with how the cell obtains the energy and matter that is required for normal function, molecular biology is mainly concerned with how the cell gets the information to perform its functions. Molecular biology wants to discover the flow of information in the cell. Using the metaphor of computers, the cell is the hardware while the genes are the software. In this sense, the purpose of gene therapy is to provide the cell with a new program (genetic information) so as to reprogram a dysfunctional cell to perform a normal function. The addition of a new cellular function is provided by the insertion of a foreign gene that expresses a foreign protein or a native protein at amounts that are not present in the patient.
The inhibition of a cellular function is provided by anti-sense approaches (that is acting against messenger RNA) and that includes oligonucleotides complementary to the messenger RNA sequence and ribozymes. Messenger RNA (mRNA) is an intermediate in the expression of the DNA gene. The mRNA is translated into a protein. xe2x80x9cAnti-sensexe2x80x9d methods use a RNA sequence or an oligonucleotide that is made complementary to the target mRNA sequence and therefore binds specifically to the target messenger RNA. When this anti-sense sequence binds to the target mRNA, the mRNA is somehow destroyed or blocked from being translated. Ribozymes destroy a specific mRNA by a different mechanism. Ribozymes are RNA""s that contain sequence complementary to the target messenger RNA plus a RNA sequence that acts as an enzyme to cleave the messenger RNA, thus destroying it and preventing it from being translated. When these anti-sense or ribozyme sequences are introduced into a cell, they would inactivate their specific target mRNA and reduce their disease-causing properties.
Several recessive genetic disorders are being considered for gene therapy. One of the first uses of gene therapy in humans has been used for the genetic deficiency of the adenosine deaminase (ADA) gene. Other clinical gene therapy trials have been conducted for cystic fibrosis, familial hypercholesteremia caused by a defective LDL-receptor gene and partial omithine transcarbomylase deficiency. Both indirect and direct gene therapy approaches are being developed for Duchenne muscular dystrophy. Patients with this type of muscular dystrophy eventually die from loss of their respiratory muscles. Direct approaches include the intramuscular injection of naked plasmid DNA or adenoviral vectors.
A wide variety of gene therapy approaches for cancer are under investigation in animals and in human clinical trials. One approach is to express in lymphocytes and in the tumor cells, cytokine genes that stimulate the immune system to destroy the cancer cells. The cytokine genes would be transferred into the lymphocytes by removing the lymphocytes from the body and infecting them with a retroviral vector carrying the cytokine gene. The tumor cells would be similarly genetically modified by this indirect approach to express cytokines within the tumor. Direct approaches involving the expression of cytokines in tumor cells in situ are also being considered. Other genes besides cytokines may be able to induce an immune response against the cancer. One approach that has entered clinical trials is the direct injection of HLA-B7 gene (which encodes a potent immunogen) within lipid vesicles into malignant melanomas in order to induce a more effective immune response against the cancer.
xe2x80x9cSuicidexe2x80x9d genes are genes that kill cells that express the gene. For example, the diphtheria toxin gene directly kills cells. The Herpes thymidine kinase (TK) gene kills cells in conjunction with acyclovir (a drug used to treat Herpes viral infections). Other gene therapy approaches take advantage of our knowledge of oncogenes and suppressor tumor genesxe2x80x94also known as anti-oncogenes. The loss of a functioning anti-oncogene plays a decisive role in childhood tumors such as retinoblastoma, osteosarcoma and Wilms tumor and may play an important role in more common tumors such as lung, colon and breast cancer. Introduction of the normal anti-oncogene back into these tumor cells may convert them back to normal cells. The activation of oncogenes also plays an important role in the development of cancers. Since these oncogenes operate in a xe2x80x9cdominantxe2x80x9d fashion, treatment will require inactivation of the abnormal oncogene. This can be done using either xe2x80x9canti-sensexe2x80x9d or ribozyme methods that selectively inactivate a specific messenger RNA in a cell.
Gene therapy can be used as a type of vaccination to prevent infectious diseases and cancer. When a foreign gene is transferred into a cell and the protein is made, the foreign protein is presented to the immune system differently from simply injecting the foreign protein into the body. This different presentation is more likely to cause a cell-mediated immune response which is important for fighting latent viral infections such as human immunodeficiency virus (HIV causes AIDS), Herpes and cytomegalovirus. Expression of the viral gene within a cell simulates a viral infection and induces a more effective immune response by fooling the body that the cell is actually infected by the virus, without the danger of an actual viral infection.
One direct approach uses the direct intramuscular injection of naked plasmid DNA to express a viral gene in muscle cells. The xe2x80x9cgunxe2x80x9d has also been shown to be effective at inducing an immune response by expressing foreign genes in the skin. Other direct approaches involving the use of retroviral, vaccinia or adenoviral vectors are also being developed. An indirect approach has been developed to remove fibroblasts from the skin, infect them with a retroviral vector carrying a viral gene and transplant the cells back into the body. The envelope gene from the AIDS virus (HIV) is often used for these purposes. Many cancer cells express specific genes that normal cells do not. Therefore, these genes specifically expressed in cancer cells can be used for immunization against cancer.
Besides the above immunization approaches, several other gene therapies are being developed for treating infectious disease. Most of these new approaches are being developed for HIV infection and AIDS. Many of them will involve the delivery of anti-sense or ribozyme sequences directed against the particular viral messenger RNA. These anti-sense or ribozyme sequences will block the expression of specific viral genes and abort the viral infection without damaging the infected cell. Another approach somewhat similar to the ant-sense approaches is to overexpress the target sequences for these regulatory HIV sequences.
Gene therapy efforts would be directed at lowering the risk factors associated with atherosclerosis. Overexpression of the LDL receptor gene would lower blood cholesterol in patients not only with familial hypercholesteremia but with other causes of high cholesterol levels. The genes encoding the proteins for HDL (xe2x80x9cthe good cholesterolxe2x80x9d) could be expressed also in various tissues. This would raise HDL levels and prevent atherosclerosis and heart attacks. Tissue plasminogen activator (tPA) protein is being given to patients immediately after their myocardial infarction to digest the blood clots and open up the blocked coronary blood vessels. The gene for tPA could be expressed in the endothelial cells lining the coronary blood vessels and thereby deliver the tPA locally without providing tPA throughout the body. Another approach for coronary vessel disease is to express a gene in the heart that produces a protein that causes new blood vessels to grow. This would increase collateral blood flow and prevent a myocardial infarction from occurring.
Neurodegenerative disorders such as Parkinson""s and Alzheimer""s diseases are good candidates for early attempts at gene therapy. Arthritis could also be treated by gene therapy. Several proteins and their genes (such as the IL-1 receptor antagonist protein) have recently been discovered to be anti-inflammatory. Expression of these genes in joint (synovial) fluid would decrease the joint inflammation and treat the arthritis.
In addition, methods are being developed to directly modify the sequence of target genes and chromosomal DNA. The delivery of a nucleic acid or other compound that modifies the genetic instruction (e.g., by homologous recombination) can correct a mutated gene or mutate a functioning gene.
Polymers for Drug and Nucleic Acid Delivery
Polymers are used for drug delivery for a variety of therapeutic purposes. Polymers have also been used in research for the delivery of nucleic acids (polynucleotides and oligonucleotides) to cells with an eventual goal of providing therapeutic processes. Such processes have been termed gene therapy or anti-sense therapy. One of the several methods of nucleic acid delivery to the cells is the use of DNA-polycation complexes. It has been shown that cationic proteins like histones and protamines or synthetic polymers like polylysine, polyarginine, polyomithine, DEAE dextran, polybrene, and polyethylenimine may be effective intracellular delivery agents while small polycations like spermine are ineffective. The following are some important principles involving the mechanism by which polycations facilitate uptake of DNA:
Polycations provide attachment of DNA to the cell surface. The polymer forms a cross-bridge between the polyanionic nucleic acids and the polyanionic surfaces of the cells. As a result the main mechanism of DNA translocation to the intracellular space might be non-specific adsorptive endocytosis which may be more effective then liquid endocytosis or receptor-mediated endocytosis. Furthermore, polycations are a convenient linker for attaching specific ligands to DNA and as result, DNA- polycation complexes can be targeted to specific cell types.
Polycations protect DNA in complexes against nuclease degradation. This is important for both extra- and intracellular preservation of DNA. Gene expression is also enabled or increased by preventing endosome acidification with NH4Cl or chloroquine. Polyethylenimine, which facilitates gene expression without additional treatments, probably disrupts endosomal function itself. Disruption of endosomal function has also been accomplished by linking to the polycation endosomal-disruptive agents such as fusion peptides or adenoviruses.
Polycations can also facilitate DNA condensation. The volume which one DNA molecule occupies in a complex with polycations is drastically lower than the volume of a free DNA molecule. The size of a DNA/polymer complex is probably critical for gene delivery in vivo. In terms of intravenous injection, DNA needs to cross the endothelial barrier and reach the parenchymal cells of interest. The largest endothelia fenestrae (holes in the endothelial barrier) occur in the liver and have an average diameter of 100 nm. The trans-epithelial pores in other organs are much smaller, for example, muscle endothelium can be described as a structure which has a large number of small pores with a radius of 4 nm, and a very low number of large pores with a radius of 20-30 nm. The size of the DNA complexes is also important for the cellular uptake process. After binding to the cells the DNA-polycation complex should be taken up by endocytosis. Since the endocytic vesicles have a homogenous internal diameter of about 100 nm in hepatocytes and are of similar size in other cell types, DNA complexes smaller than 100 nm are preferred.
Condensation of DNA
A significant number of multivalent cations with widely different molecular structures have been shown to induce condensation of DNA.
Two approaches for compacting (used herein as an equivalent to the term condensing) DNA:
1. Multivalent cations with a charge of three or higher have been shown to condense DNA. These include spermidine, spermine, Co(NH3)63+,Fe3+, and natural or synthetic polymers such as histone H1, protamine, polylysine, and polyethylenimine. Analysis has shown DNA condensation to be favored when 90% or more of the charges along the sugar-phosphate backbone are neutralized.
2. Polymers (neutral or anionic) which can increase repulsion between DNA and its surroundings have been shown to compact DNA. Most significantly, spontaneous DNA self-assembly and aggregation process have been shown to result from the confinement of large amounts of DNA, due to excluded volume effect.
Depending upon the concentration of DNA, condensation leads to three main types of structures:
1) In extremely dilute solution (about 1 xcexcg/mL or below), long DNA molecules can undergo a monomolecular collapse and form structures described as toroid.
2) In very dilute solution (about 10 xcexcg/mL) microaggregates form with short or long molecules and remain in suspension. Toroids, rods and small aggregates can be seen in such solution.
3) In dilute solution (about 1 mg/mL) large aggregates are formed that sediment readily.
Toroids have been considered an attractive form for gene delivery because they have the smallest size. While the size of DNA toroids produced within single preparations has been shown to vary considerably, toroid size is unaffected by the length of DNA being condensed. DNA molecules from 400 bp to genomic length produce toroids similar in size. Therefore one toroid can include from one to several DNA molecules. The kinetics of DNA collapse by polycations that resulted in toroids is very slow. For example DNA condensation by Co(NH3)6Cl3 needs 2 hours at room temperature.
The mechanism of DNA condensation is not clear. The electrostatic force between unperturbed helices arises primarily from a counterion fluctuation mechanism requiring multivalent cations and plays a major role in DNA condensation. The hydration forces predominate over electrostatic forces when the DNA helices approach closer then a few water diameters. In a case of DNA-polymeric polycation interactions, DNA condensation is a more complicated process than the case of low molecular weight polycations. Different polycationic proteins can generate toroid and rod formation with different size DNA at a ratio of positive to negative charge of two to five. T4 DNA complexes with polyarginine or histone can form two types of structures; an elongated structure with a long axis length of about 350 nm (like free DNA) and dense spherical particles. Both forms exist simultaneously in the same solution. The reason for the co-existence of the two forms can be explained as an uneven distribution of the polycation chains among the DNA molecules. The uneven distribution generates two thermodynamically favorable conformations.
The electrophoretic mobility of DNA-polycation complexes can change from negative to positive in excess of polycation. It is likely that large polycations don""t completely align along DNA but form polymer loops that interact with other DNA molecules. The rapid aggregation and strong intermolecular forces between different DNA molecules may prevent the slow adjustment between helices needed to form tightly packed orderly particles.
As previously stated, preparation of polycation-condensed DNA particles is of particular importance for gene therapy, more specifically, particle delivery such as the design of non-viral gene transfer vectors. Optimal transfection activity in vitro and in vivo can require an excess of polycation molecules. However, the presence of a large excess of polycations may be toxic to cells and tissues. Moreover, the non-specific binding of cationic particles to all cells forestalls cellular targeting. Positive charge also has an adverse influence on biodistribution of the complexes in vivo.
Several modifications of DNA-cation particles have been created to circumvent the nonspecific interactions of the DNA-cation particle and the toxicity of cationic particles. Examples of these modifications include attachment of steric stabilizers, e.g. polyethylene glycol, which inhibit nonspecific interactions between the cation and biological polyanions. Another example is recharging the DNA particle by the additions of polyanions which interact with the cationic particle, thereby lowering its surface charge, i.e. recharging of the DNA particle U.S. Ser. No. 09/328,975. Another example is cross-linking the polymers and thereby caging the complex U.S. Ser. No. 08/778,657, now U.S. Pat. No. 6,126,964, U.S. Ser. No. 09/000,692, now U.S. Pat. No. 6,339,067, U.S. Ser. No. 97/24089, U.S. Ser. No. 09/070,299, now abandoned, and U.S. Ser. No. 09/464,871, now abandoned. Nucleic acid particles can be formed by the formation of chemical bonds and template polymerization U.S. Ser. No. 08/778,657, now U.S. Pat. No. 6,126,164, U.S. Ser. No. 09/000,692, now U.S. Pat. No. 6,338,067, U.S. Ser. No. 97/24089, U.S. Ser. No. 09/070,299, now abandoned, and U.S. Ser. No. 09/464,871, now abandoned.
A problem with these modifications is that they are most likely irreversible rendering the particle unable to interact with the cell to be transfected, and/or incapable of escaping from the lysosome once taken into a cell, and/or incapable of entering the nucleus once inside the cell. A method for formation of DNA particles that is reversible under conditions found in the cell may allow for effective delivery of DNA. The conditions that cause the reversal of particle formation may be, but not limited to, the pH, ionic strength, oxidative or reductive conditions or agents, or enzymatic activity.
DNA Template Polymerization
Low molecular weight cations with valency, i.e. charge, less than +3 fail to condense DNA in aqueous solutions under normal conditions. However, cationic molecules with the charge less than +3 can be polymerized in the presence of DNA and the resulting polymers can cause DNA to condense into compact structures. Such an approach is known in synthetic polymer chemistry as template polymerization. During this process, monomers (which are initially weakly associated with the template) are positioned along template""s backbone, thereby promoting their polymerization. Weak electrostatic association of the nascent polymer and the template becomes stronger with chain growth of the polymer. Trubetskoy et al used two types of polymerization reactions to achieve DNA condensation: step polymerization and chain polymerization (V S Trubetskoy, V G Budker, L J Hanson, P M Slattum, J A Wolff, L E Hagstrom. Nucleic Acids Res. 26:4178-4185, 1998) U.S. Ser. No. 08/778,657, now U.S. Pat. No. 6,126,964, U.S. Ser. No. 09/000,692, now U.S. Pat. No. 6,339,067, U.S. Ser. No. 97/24089, U.S. Ser. No. 09/070,299, now abandoned, and U.S. Ser. No. 09/464,871 now abandoned. Bis(2-aminoethyl)-1,3-propanediamine (AEPD), a tetramine with 2.5 positive charges per molecule at pH 8 was polymerized in the presence of plasmid DNA using cleavable disulfide amino-reactive cross-linkers dithiobis (succinimidyl propionate) and dimethyl-3,3xe2x80x2-dithiobispropionimidate. Both reactions yielded DNA/polymer complexes with significant retardation in agarose electrophoresis gels demonstrating significant binding and DNA condensation. Treatment of the polymerized complexes with 100 mM dithiothreitol (DTT) resulted in the pDNA returning to its normal supercoiled position following electrophoresis. The template dependent polymerization process was also tested using a 14 mer peptide encoding the nuclear localizing signal (NLS) of SV40 T antigen (SEQ ID NO: 1) as a cationic xe2x80x9cmacromonomerxe2x80x9d. Other studies included pegylated comonomer (PEG-AEPD) into the reaction mixture and resulted in xe2x80x9cwormxe2x80x9d-like structures (as judged by transmission electron microscopy) that have previously been observed with DNA complexes formed from block co-polymers of polylysine and PEG (M A Wolfert, E H Schacht, V Toncheva, K Ulbrich, O Nazarova, L W Seymour. Human Gene Ther. 7:2123-2133, 1996). Blessing et al used bisthiol derivative of spermine and reaction of thiol-disulfide exchange to promote chain growth. The presence of DNA accelerated the polymerization reaction as measured the rate of disappearance of free thiols in the reaction mixture (T Blessing, J S Remy, J P Behr. J. Am. Chem. Soc. 120:8519-8520, 1998).
xe2x80x9cCagingxe2x80x9d of Polycation-condensed DNA Particles
The stability of DNA nanoassemblies based on DNA condensation is generally low in vivo because they easily engage in polyion exchange reactions with strong polyanions. The process of exchange consists of two stages: 1) rapid formation of a triple DNA-polycation-polyanion complex, 2) slow substitution of one same-charge polyion with another. At equilibrium conditions, the whole process eventually results in formation of a new binary complex and an excess of a third polyion. The presence of low molecular weight salt can greatly accelerate such exchange reactions, which often result in complete disassembly of condensed DNA particles. Hence, it is desirable to obtain more colloidally stable structures where DNA would stay in its condensed form in complex with corresponding polycation independently of environment conditions.
The complete DNA condensation upon neutralization of only 90% of the polymer""s phosphates results in the presence of unpaired positive charges in the DNA particles. If the polycation contains such reactive groups, such as primary amines, these unpaired positive charges may be modified. This modification allows practically limitless possibilities of modulating colloidal properties of DNA particles via chemical modifications of the complex. We have demonstrated the utility of such reactions using traditional DNA-poly-L-lysine (DNA/PLL) system reacted with the cleavable cross-linking reagent dimethyl-3,3xe2x80x2-dithiobispropionimidate (DTBP) which reacts with primary amino groups with formation of amidines (V S Trubetskoy, A Loomis, P M Slattum, J E Hagstrom, V G Budker, J A Wolff. Bioconjugate Chem. 10:624-628, 1999) U.S. Ser. No. 08/778,657 now U.S. Pat. No. 6,126,964, U.S. Ser. No. 09/000,692 now U.S. Pat. No. 6,339,067 PCT/US97/24089, U.S. Ser. No. 09/070,299 now abandoned, and U.S. Ser. No. 09/464,871 now abandoned. Similar results were achieved with other polycations including poly(allylamine) and histone H1. The use of another bifucntional reagent, glutaraldehyde, has been described for stabilization of DNA complexes with cationic peptide CWK18 (R C Adam, K G Rice. J. Pharm. Sci. 739-746, 1999).
Recharging
The caging approach described above could lead to more colloidally stable DNA assemblies. However, this approach may not change the particle surface charge. Caging with bifunctional reagents, which preserve positive charge of amino group, keeps the particle positive. However, negative surface charge would be more desirable for many practical applications, i.e. in vivo delivery. The phenomenon of surface recharging is well known in colloid chemistry and is described in great detail for lyophobic/lyophilic systems (for example, silver halide hydrosols). Addition of polyion to a suspension of latex particles with oppositely-charged surface leads to the permanent absorption of this polyion on the surface and, upon reaching appropriate stoichiometry, changing the surface charge to opposite one. This whole process is salt dependent with flocculation to occur upon reaching the neutralization point.
We have demonstrated that similar layering of polyelectrolytes can be achieved on the surface of DNA/polycation particles (V S Trubetskoy, A Loomis, J E Hagstrom, V G Budker, J A Wolff. Nucleic Acids Res. 27:3090-3095, 1999). The principal DNA-polycation (DNA/pC) complex used in this study was DNA/PLL (1:3 charge ratio) formed in low salt 25 mM HEPES buffer and recharged with increasing amounts of various polyanions. The DNA particles were characterized after addition of a third polyion component to a DNA/polycation complex using a new DNA condensation assay (V S Trubetskoy, P M Slattum, J E Hagstrom, J A Wolff, V G Budker. Anal. Biochem. 267:309-313, 1999) and static light scattering. It has been found that certain polyanions such as poly(methacrylic acid) and poly(aspartic acid) decondensed DNA in DNA/PLL complexes. Surprisingly, polyanions of lower charge density such as succinylated PLL and poly(glutamic acid), even when added in 20-fold charge excess to condensing polycation (PLL) did not decondense DNA in DNA/PLL (1:3) complexes. Further studies have found that displacement effects are salt-dependent. In addition, poly-L-glutamic acid but not the relatively weaker polyanion succinylated poly-L-lysine (SPLL) displaces DNA at higher sodium chloride concentrations. Measurement of xcex6-potential of DNA/PLL particles during titration with SPLL revealed the change of particle surface charge at approximately the charge equivalency point. Thus, it can be concluded that addition of low charge density polyanion to the cationic DNA/PLL particles results in particle surface charge reversal while maintaining condensed DNA core intact. Finally, DNA/polycation complexes can be both recharged and crosslinked or caged U.S. Ser. No. 08/778,657, now U.S. Pat. No. 6,126,968, U.S. Ser. No. 09/000,692, now U.S. Pat. No. 6,339,067, U.S. Ser. No. 97/24089, U.S. Ser. No. 09/070,299, now abandoned and U.S. Ser. No. 09/464,871 now abandoned.
The Use of pH-Sensitive Lipids, Amphipathic Compounds, and Liposomes for Drug and Nucleic Acid Delivery
After the landmark description of DOTMA (N-[1-(2,3-dioleyloxy)propyll-N,N,N-trimethylammonium chloride) [Felgner, P L, Gadek, T R, Holm, M, et al. Lipofection: a highly efficient, lipid-mediated DNA-transfection procedure. Proc. Natl. Acad. Sci. USA. 1987;84:7413-7417], a plethora of cationic lipids have been synthesized. Basically, all the cationic lipids are amphipathic compounds that contain a hydrophobic domain, a spacer, and positively-charged amine. The hydrophobic domains are typically hydrocarbon chains such as fatty acids derived from oleic or myristic acid. The hydrocarbon chains are often joined either by ether or ester bonds to a spacer such as glycerol. Quaternary amines often compose the cationic groups. Usually, the cationic lipids are mixed with a fusogenic lipid such as DOPE (dioleoyl phosphatidyl ethanolamine) to form liposomes. The mixtures are mixed in chloroform that is then dried. Water is added to the dried lipid film and unilamellar liposomes form during sonication. Multilamellar cationic liposomes and cationic liposomes/DNA complexes prepared by the reverse-phase evaporation method have also been used for transfection. Cationic liposomes have also been prepared by an ethanol injection technique.
Several cationic lipids contain a spermine group for binding to DNA. DOSPA, the cationic lipid within the LipofectAMINE formulation (Life Technologies) contains a spermine linked via a amide bond and ethyl group to a trimethyl, quaternary amine [Hawley-Nelson, P, Ciccarone, V and Jessee, J. Lipofectamine reagent: A new, higher efficiency polycationic liposome transfection reagent. Focus 1993; 15:73-79]. A French group has synthesized a series of cationic lipids such as DOGS (dioctadecylglycinespermine) that contain spermine [Remy, J-S, Sirlin, C, Vierling, P, et al. Gene transfer with a series of lipophilic DNA-binding molecules. Bioconjugate Chem. 1994;5:647-654]. DNA has also been transfected by lipophilic polylysines which contain dipalmotoylsuccinylglycerol chemically-bonded to low molecular weight (xcx9c3000 MW) polylysine [Zhou, X, Kilbanov, A and Huang, L. Lipophilic polylysines mediate efficient DNA transfection in mammalian cells. Biochim. Biophys. Acta 1991;1065:8-14. Zhou, X and Huang, L. DNA transfection mediated by cationic liposomes containing lipopolylysine: Characterization and mechanism of action. Biochim. Biophys. Acta 1994;1195-203].
Other studies have used adjuvants with the cationic liposomes. Transfection efficiency into Cos cells was increased when amphiphilic peptides derived from influenza virus hemagglutinin were added to DOTMA/DOPE liposomes [Kamata, H, Yagisawa, H, Takahashi, S, et al. Amphiphilic peptides enhance the efficiency of liposome-mediated DNA transfection. Nucleic Acids Res. 1994;22:536-537]. Cationic lipids have been combined with galactose ligands for targeting to the hepatocyte asialoglycoprotein receptor [Remy, J-S, Kichler, A, Mordvinov, V, et al. Targeted gene transfer into hepatoma cells with lipopolyamine-condensed DNA particles presenting galactose ligands: A stage toward artificial viruses. Proc. Natl. Acad. Sci. USA 1995;92:1744-1748]. Thiol-reactive phospholipids have also been incorporated into cationic lipid/pDNA complexes to enable cellular binding even when the net charge of the complex is not positive [Kichier, A, Remy, J-S, Boussif, O, et al. Efficient gene delivery with neutral complexes of lipospermine and thiol-reactive phospholipids. Biochem. Biophys. Res. Comm. 1995;209:444-450]. DNA-dependent template process converted thiol-containing detergent possessing high critical micelle concentration into dimeric lipid-like molecule with apparently low water solubility.
Cationic liposomes may deliver DNA either directly across the plasma membrane or via the endosome compartment. Regardless of its exact entry point, much of the DNA within cationic liposomes does accumulate in the endosome compartment. Several approaches have been investigated to prevent loss of the foreign DNA in the endosomal compartment by protecting it from hydrolytic digestion within the endosomes or enabling its escape from endosomes into the cytoplasm. They include the use of acidotropic (lysomotrophic), weak amines such as chloroquine that presumably prevent DNA degradation by inhibiting endosomal acidification [Legendre, J. and Szoka, F. Delivery of plasmid DNA into mammalian cell lines using pH-sensitive liposomes: Comparison with cationic liposomes. Pharmaceut. Res. 9, 1235-1242 (1992)]. Viral fusion peptides or whole virus have been included to disrupt endosomes or promote fusion of liposomes with endosomes, and facilitate release of DNA into the cytoplasm [Kamata, H., Yagisawa, H., Takahashi, S. and Hirata, H. Amphiphilic peptides enhance the efficiency of liposome-mediated DNA transfection. Nucleic Acids Res. 22, 536-537 (1994). Wagner, E., Curiel, D. and Cotten, M. Delivery of drugs, proteins and genes into cells using transferrin as a ligand for receptor-mediated endocytosis. Advanced Drug Delivery Reviews 14, 113-135 (1994)].
Knowledge of lipid phases and membrane fusion has been used to design potentially more versatile liposomes that exploit the endosomal acidification to promote fusion with endosomal membranes. Such an approach is best exemplified by anionic, pH-sensitive liposomes that have been designed to destabilize or fuse with the endosome membrane at acidic pH [Duzgunes, N., Straubinger, R. M., Baldwin, P. A. and Papahadjopoulos, D. PH-sensitive liposomes. (eds Wilschub, J. and Hoekstra, D.) p. 713-730 (Marcel Deker INC, 1991)]. All of the anionic, pH-sensitive liposomes have utilized phosphatidylethanolamine. (PE) bilayers that are stabilized at non-acidic pH by the addition of lipids that contain a carboxylic acid group. Liposomes containing only PE are prone to the inverted hexagonal phase (HII). In pH-sensitive, anionic liposomes, the carboxylic acid""s negative charge increases the size of the lipid head group at pH greater than the carboxylic acid""s pKa and thereby stabilizes the phosphatidylethanolamine bilayer. At acidic pH conditions found within endosomes, the uncharged or reduced charge species is unable to stabilize the phosphatidylethanolamine-rich bilayer. Anionic, pH-sensitive liposomes have delivered a variety of membrane-impermeable compounds including DNA. However, the negative charge of these pH-sensitive liposomes prevents them from efficiently taking up DNA and interacting with cells; thus decreasing their utility for transfection. We have described the use of cationic, pH-sensitive liposomes to mediate the efficient transfer of DNA into a variety of cells in culture U.S. Ser. No. 08/530,598, now U.S. Pat. No. 5,774,335 and U.S. Ser. No. 09/020,566, now U.S. Pat. No. 6,180,784.
The Use of pH-Sensitive Polymers for Drug and Nucleic Acid Delivery
Polymers that pH-sensitive are have found broad application in the area of drug delivery exploiting various physiological and intracellular pH gradients for the purpose of controlled release of drugs (both low molecular weight and polymeric). pH sensitivity can be broadly defined as any change in polymer""s physico-chemical properties over certain range of pH. More narrow definition demands significant changes in the polymer""s ability to retain (release) a bioactive substance (drug) in a physiologically tolerated pH range (usually pH 5.5-8). pH-sensitivity presumes the presence of ionizable groups in the polymer (polyion). All polyions can be divided into three categories based on their ability to donate or accept protons in aqueous solutions: polyacids, polybases and polyampholytes. Use of pH-sensitive polyacids in drug delivery applications usually relies on their ability to become soluble with the pH increase (acid/salt conversion), to form complex with other polymers over change of pH or undergo significant change in hydrophobicity/hydrophilicity balance. Combinations of all three above factors are also possible.
Copolymers of polymethacrylic acid (Eudragit S, Rohm America) are known as polymers which are insoluble at lower pH but readily solubilized at higher pH, so they are used as enteric coatings designed to dissolve at higher intestinal pH (Z Hu et al. J. Drug Target., 7, 223, 1999). A typical example of pH-dependent complexation is copolymers of polyacrylate(graft)ethyleneglycol which can be formulated into various pH-sensitive hydrogels which exhibit pH-dependent swelling and drug release (F Madsen et al., Biomaterials, 20, 1701, 1999). Hydropbobically-modified N-isopropylacrylamide-methacrylic acid copolymer can render regular egg PC liposomes pH-sensitive by pH-dependent interaction of grafted aliphatic chains with lipid bilayer (O Meyer et al., FEBS Lett., 421, 61, 1998). Polymers with pH-mediated hydrophobicity (like polyethylacrylic acid) can be used as endosomal disrupters for cytoplasmic drug delivery (Murthy, N., Robichaud, J. R., Tirrell, D. A., Stayton, P. S., Hoffman, A. S. J. Controlled Release 61, 137, 1999).
Polybases have found broad applications as agents for nucleic acid delivery in transfection/gene therapy applications due to the fact they are readily interact with polyacids. A typical example is polyethyleneimine (PEI). This polymer secures nucleic acid electrostatic adsorption on the cell surface followed by endocytosis of the whole complex. Cytoplasmic release of the nucleic acid occurs presumably via the so called xe2x80x9cproton spongexe2x80x9d effect according to which pH-sensitivity of PEI is responsible for endosome rupture due to osmotic swelling during its acidification (O Boussif et al. Proc. Natl. Acad. Sci. USA 92, 7297, 1995). Cationic acrylates possess the similar activity (for example, poly-((2-dimethylamino)ethyl methacrylate) (P van de Wetering et al. J. Controlled Release 64, 193, 2000). However, polybases due to their polycationic nature pH-sensitive polybases have not found broad in vivo application so far, due to their acute systemic toxicity in vivo (J H Senior, Biochim. Biophys. Acta, 1070, 173, 1991). Milder polybases (for example, linear PEI) are better tolerated and can be used systemically for in vivo gene transfer (D Goula et al. Gene Therapy 5, 712, 1998).
Membrane Active Compounds
Many biologically active compounds, in particular large and/or charged compounds, are incapable of crossing biological membranes. In order for these compounds to enter cells, the cells must either take them up by endocytosis, into endosomes, or there must be a disruption of the cellular membrane to allow the compound to cross. In the case of endosomal entry, the endosomal membrane must be disrupted to allow for the entrance of the compound in the interior of the cell. Therefore, either entry pathway into the cell requires a disruption of the cellular membrane. There exist compounds termed membrane active compounds that disrupt membranes. One can imagine that if the membrane active agent were operative in a certain time and place it would facilitate the transport of the biologically active compound across the biological membrane. The control of when and where the membrane active compound is active is crucial to effective transport. If the membrane active compound is too active or active at the wrong time, then no transport occurs or transport is associated with cell rupture and thereby cell death. Nature has evolved various strategies to allow for membrane transport of biologically active compounds including membrane fusion and the use membrane active compounds whose activity is modulated such that activity assists transport without toxicity. Many lipid-based transport formulations rely on membrane fusion and some membrane active peptides"" activities are modulated by pH. In particular, viral coat proteins are often pH-sensitive, inactive at neutral or basic pH and active under the acidic conditions found in the endosome.
Small Molecular Endosomolytic Agents
A cellular transport step that has attracted attention for gene transfer is that of DNA release from intracellular compartments such as endosomes (early and late), lysosomes, phagosomes, vesicle, endoplasmic reticulum, golgi apparatus, trans golgi network (TGN), and sarcoplasmic reticulum. Release includes movement out of an intracellular compartment into cytoplasm or into an organelle such as the nucleus. A number of chemicals such as chloroquine, bafilomycin or Brefeldin A1 have been used to disrupt or modify the trafficking of molecules through intracellular pathways. Chloroquine decreases the acidification of the endosomal and lysosomal compartments but also affects other cellular functions. Brefeldin A, an isoprenoid fungal metabolite, collapses reversibly the Golgi apparatus into the endoplasmic reticulum and the early endosomal compartment into the trans-Golgi network (TGN) to form tubules. Bafilomycin A1, a macrolide antibiotic is a more specific inhibitor of endosomal acidification and vacuolar type H+-ATPase than chloroquine.
Viruses, Proteins and Peptides for Disruption of Endosomes and Endosomal Function
Viruses such as adenovirus have been used to induce gene release from endosomes or other intracellular compartments (D. Curiel, Agarwal, S., Wagner, E., and Cotten, M. PNAS 88:8850, 1991). Rhinovirus has also been used for this purpose (W. Zauner et al. J. Virology 69:1085-92, 1995). Viral components such as influenza virus hemagglutinin subunit HA-2 analogs has also been used to induce endosomal release (E. Wagner et al. PNAS 89:7934, 1992). Amphipathic peptides resembling the N-terminal HA-2 sequence has been studied (K. Mechtler and E. Wagner, New J. Chem. 21:105-111, 1997). Parts of the pseudonmonas exotoxin and diptheria toxin have also been used for drug delivery (I. Pastan and D. FitzGerald. J. Biol. Chem. 264:15157, 1989).
A variety of synthetic amphipathic peptides have been used to enhance transfection of genes (N. Ohmori et al. Biochem. Biophys. Res. Commun. 235:726, 1997). The ER-retaining signal (KDEL sequence) has been proposed to enhance delivery to the endoplasmic reticulum and prevent delivery to lysosomes (S. Seetharam et al. J. Biol. Chem. 266:17376, 1991).
The present invention provides for a new group of membrane active compounds that can enhance the delivery of nucleic acids.
Other Cellular and Intracellular Gradients Useful for Delivery
Nucleic acid and gene delivery may involve the biological pH gradient that is active within organisms as a factor in delivering a polynucleotide to a cell. Different pathways that may be affected by the pH gradient include cellular transport mechanisms, endosomal disruption/breakdown, and particle disassembly (release of the DNA). Other gradients that can be useful in gene therapy research involve ionic gradients that are related to cells. For example, both Na+ and K+ have large concentration gradients that exist across the cell membrane. Systems containing metal-binding groups can utilize such gradients to influence delivery of a polynucleotide to a cell. Changes in the osmotic pressure in the endosome also have been used to disrupt membranes and allow for transport across membrane layer. Buffering of the endosome pH may cause these changes in osmotic pressure. For example, the xe2x80x9cproton spongexe2x80x9d effect of PEI (O Boussif et al. Proc. Natl. Acad. Sci. USA 92, 7297, 1995) and certain polyanions (Murthy, N., Robichaud, J. R., Tirrell, D. A., Stayton, P. S., Hoffman, A. S. Journal of Controlled Release 1999, 61, 137) are postulated to cause an increase in the ionic strength inside of the endosome, which causes a increase in osmotic pressure. This pressure increase results in membrane disruption and release of the contents of the endosome.
In addition to pH and other ionic gradients, there exist other difference in the chemical environment associated with cellular activities that may be used in gene delivery. In particular enzymatic activity both extra and intracellularly may be used to deliver the gene of interest either by aiding in the delivery to the cell or escape from intracellular compartments. Proteases, found in serum, lysosome and cytoplasm, may be used to disrupt the particle and allow its interaction with the cell surface or cause it fracture the intracellular compartment, e.g. endosome or lysosome, allowing the gene to be released intracellularly.
Compounds and methods are described for enhancing the delivery of biologically active compounds including peptides, small molecular drugs and nucleic acids. Novel pH-labile and membrane active compounds are described. Some of these compounds are cleaved at acidic pH; thereby increasing their membrane activity. Some of these novel compounds also have use as detergents.
The present invention relates to the delivery of desired compounds (e.g., drugs and nucleic acids) into cells using pH-labile polymers and membrane active compounds coupled with labile compounds. The present invention provides compositions and methods for delivery and release of a compound of interest to a cell.
Noncovalent molecule-molecule interactions, which are the basis of DNA-polycation particle formation, rely on discreet interactions between the functional groups on the interacting molecules. It is quite apparent that if one modifies the interacting functional groups, one changes the whole molecule-molecule interaction. This is true for small molecules and large macromolecules. For example methyl alcohol is a liquid capable of hydrogen bonding with water, which confers the compound with water solubility. In contrast, conversion of the alcohol functional group to a methyl ether to form dimethyl ether renders the molecule in to a water insoluble gas. Many other examples may be observed in small molecular weight drug-receptor interactions. DNA interacts with the polycation poly-L-lysine to form condensed DNA particles. If the amino groups of poly-L-lysine are converted to carboxylate groups as in succinylated poly-L-lysine there is no interaction with the polyanion DNA. The identities of the functional groups on a molecule dictate its interactions with other molecules. Therefore, the ability to control the identity of the function groups on a molecule allows one to control its interactions. As a consequence, controlled and reversible functional group modification is important if one want to modulate a molecule""s interactions. This control is of particular importance when the molecule in question is biologically active. For example, one may not want to administer cytotoxic drugs directly. In this case, one may administer a prodrug that is itself inactive, but becomes active by change(s) in functional group(s) after delivery.
Prior to the present invention, delivery systems suffered from slow reversibility- or irreversibility- and/or high toxicity. For example, many cationic polymers such as poly-L-lysine (PLL) and polyethylenimine (PEI) form positively charged condensed particles with DNA. In vitro, these particles are relatively good reagents, compared to DNA alone, for the transfer of DNA into cells. However, these particles are poor transfer reagents in vivo due to their toxicity and relatively stable interaction with DNA, which renders their complexation irreversible under physiological conditions. There are several barriers that these complexes must overcome for them to be efficient gene transfer reagents: stable enough to protect the DNA from nucleases and aid in delivery to the cell, yet the DNA polycation complex must be disruptedxe2x80x94thereby allowing transcription to occur. Additionally, if the complex is taken into the cell through the process of endocytosis, the complex must escape the endosome before being taken into the lysosome and being digested.
To increase the stability of DNA particles in serum, certain embodiments of the present invention provide polyanions that form a third layer in the DNA-polycation complex and it is negatively charged. To assist in the disruption of the DNA complexes, certain embodiments of the present invention provide synthesized polymers that are cleaved in the acid conditions found in the endosome (i.e., pH 5-7). For example, the present invention provides for the cleavage or alteration of a labile chemical group once the complex is in the desired environment: cleavage of the polymer backbone resulting in smaller polyions or cleavage of the link between the polymer backbone and the ion resulting in an ion and an polymer. In either case, the number of molecules in the endosome increases. This alteration may facilitate the release of the delivered compound into the cytoplasm. Although it is not necessary to understand the mechanism in order to use the present invention, and it is not intended that the present invention be so limited, one can contemplate a number of mechanisms by which the delivery is enhanced by the present invention. In some instances cleavage of the labile polymer leads to release and enhanced delivery of the therapeutic agent (biologically active compound). Cleavage can also lead to enhanced membrane activity so that the pharmaceutical (biologically active compound) is more effectively delivered to the cell. This can occur in the environs of a tumor or inflamed tissue or within an acidic sub-cellular compartment. Cleavage can also cause an osmotic shock to the endosomes and disrupts the endosomes. If the polymer backbone is hydrophobic it may interact with the membrane of the endosome. Either effect disrupts the endosome and thereby assists in release of delivered compound.
In some embodiments of the present invention, membrane active agents are complexed with the delivery system such that they are inactive and not membrane active within the complex but become active when released, following the chemical conversion of the labile group. The membrane active agents may be used to assist in the disruption of the endosome or other cellular compartment. They can also be used to enable selective delivery or toxicity to tumors or tissues that are acidic. Many membrane active agents such as the peptides melittin and pardaxin and various viral proteins and peptides are effective in allowing a disruption of cellular compartments such as endosomes to effect a release of its contents into a cell. However, these agents are toxic to cells both in vitro and in vivo due to the inherent nature of their membrane activity. To decrease the toxicity of these agents, the present invention provides techniques to complex or modify the agent in a way which blocks or inhibits the membrane activity of the agent but is reversible in nature so activity can be recovered when membrane activity is needed for transport of biologically active compound. The activities of these membrane active agents can be controlled in a number of different ways. For example, a modification of the agent may be made that can be cleaved off of the agent allowing the activity to return. The cleavage can occur during a natural process, such as the pH drop seen in endosomes or cleaved in the cytoplasm of cells where amounts of reducing agents become available. Cleavage of a blocking agent can occur by delivery of a cleaving agent to the blocked complex at a time when it would be most beneficial. Another exemplary method of blocking membrane active agents is to reversibly modify the agents"" functional group with an activity blocking addition (defined as xe2x80x9cCompounds or Chemical Moieties that Inhibit or Block the Membrane Activity of Another Compound or Chemical Moietyxe2x80x9d. When the blocking addition reaches an environment or an adjunct is added the reversible modification is reversed and the membrane active agent will regain activity.
In some embodiments the biologically active compound is reversibly modified, or complexed with, an interaction modifier such that the interactions between the biologically active molecule and its environs, that is its interactions with itself and other molecules, is altered when the interaction modifier is released. For example attachment of such nonionic hydrophilic groups such as polyethylene glycol and polysaccharides (e.g. starch) may decrease self-association and interactions with other molecules such as serum compounds and cellular membranes, which may be necessary for transport of the biologically active molecule to the cell. However these molecules may inhibit cellular uptake and therefore, must be lost before cellular uptake can occur. Likewise, cell targeting ligands aid in transport to a cell but may not be necessary, and may inhibit, transport into a cell. In all of these cases, the reversible attachment of the interaction modifier, through a labile bond, would be beneficial.
The present invention provides for the transfer of polynucleotides, and other biologically active compounds into cells in culture (also known as xe2x80x9cin vitroxe2x80x9d). Compounds or kits for the transfection of cells in culture is commonly sold as xe2x80x9ctransfection reagentsxe2x80x9d or xe2x80x9ctransfection kitsxe2x80x9d. The present invention also provides for the transfer of polynucleotides, and biologically active compounds into cells within tissues in situ and in vivo, and delivered intravasculary (U.S. patent application Ser. No. 08/571,536 now abandoned), intrarterially, intravenous, orally, intraduodenaly, via the jejunum (or ileum or colon), rectally, transdermally, subcutaneously, intramuscularly, intraperitoneally, intraparenterally, via direct injections into tissues such as the liver, lung, heart, muscle, spleen, pancreas, brain (including intraventricular), spinal cord, ganglion, lymph nodes, lymphatic system, adipose tissues, thryoid tissue, adrenal glands, kidneys, prostate, blood cells, bone marrow cells, cancer cells, tumors, eye retina, via the bile duct, or via mucosal membranes such as in the mouth, nose, throat, vagina or rectum or into ducts of the salivary or other exocrine glands. Compounds for the transfection of cells in vivo in a whole organism can be sold as xe2x80x9cin vivo transfection reagentsxe2x80x9d or xe2x80x9cin vivo transfection kitsxe2x80x9d or as a pharmaceutical for gene therapy.
Polymers with pH-Labile Bonds
The present invention provides a wide variety of polymers with labile groups that find use in the delivery systems of the present invention. The labile groups are selected such that they undergo a chemical transformation (e.g., cleavage) when present in physiological conditions. The chemical transformation may be initiated by the addition of a compound to the cell or may occur spontaneously when introduced into intra-and/or extra-cellular environments (e.g., the lower pH conditions of an endosome or the extracellular space surrounding tumors). The conditions under which a labile group will undergo transformation can be controlled by altering the chemical constituents of the molecule containing the labile group. For example, addition of particular chemical moieties (e.g., electron acceptors or donors) near the labile group can effect the particular conditions (e.g., pH) under which chemical transformation will occur.
In certain embodiments, the present invention provides compound delivery systems composed of polymers (e.g., cationic polymers, anionic polymers, zwitterionic and nonionic polymers) that contain pH-labile groups. The systems are relatively chemically stable until they are introduced into acidic conditions that render them unstable (labile). An aqueous solution is acidic when the concentration of protons (H+) exceed the concentration of hydroxide (OHxe2x88x92). Upon delivery to the desired location, the labile group undergoes an acid-catalyzed chemical transformation resulting in release of the delivered compound or a complex of the delivered compound. The pH-labile bond may either be in the main-chain or in the side chain. If the pH-labile bond occurs in the main chain, then cleavage of the labile bond results in a decrease in polymer length. If the pH-labile bond occurs in the side chain, then cleavage of the labile bond results in loss of side chain atoms from the polymer.
In some preferred embodiments of the present invention, nucleic acids are delivered to cells by a polymer complex containing a labile group, or groups, that undergoes chemical transformation when exposed to the low pH environment of an endosome. Such complexes provide improved nucleic acid delivery systems, as they provide for efficient delivery and low toxicity.
Polymers Containing Several Membrane Active Compounds
The present invention specifies polymers containing more than two membrane active compounds. In one embodiment, the membrane active compounds are grafted onto a preformed polymer to form a comb-type polymer, i.e. a polymer containing side chain groups. In another embodiment, the membrane active compounds are incorporated into the polymer by chain or step polymerization processes. To aid in complexation between DNA and membrane active compounds and/or to augment the membrane activity of membrane active agents, certain embodiments of the present invention have polymers composed of monomers that are themselves membrane active. These polymers are formed by attaching a membrane active compound to a preformed polymer or by polymerization of membrane active monomers.
Membrane Active Compounds Containing Labile Bonds
The inclusion of labile bonds into membrane active compounds increases their versatility in a number of ways. It can reduce their toxicity by enabling their membrane activity to be expressed in specific tissues such as tumors and inflamed joints, specific sub-cellular locations such as endosomes and lysosomes, or under specific conditions such as a reducing environment. In one embodiment of the invention, the labile bonds are pH-sensitive in that the bonds break or are cleaved when pH of their microenvironment drops below physiologic pH of 7.4 or below pH of 6.5 or below pH of 5.5. In another embodiment the labile bonds are very pH-sensitive. In yet another embodiment, the labile bonds are disulfides that are labile under physiologic conditions or that are cleaved by the addition of an exogenous reducing agent. In other embodiments, the labile bonds are acetals, ketals, enol ethers, enol esters, amides of 2,3-disubstituted maleamic acid, imines, imminiums, enamines, silyl ethers, and silyl enol ethers.
The invention also includes compounds that are of the general structure: Axe2x80x94Bxe2x80x94C wherein A is a membrane active compound, B is a labile linkage, and C is a compound that inhibits the membrane activity of compound A. Upon cleavage of B, membrane activity is restored to compound A. This cleavage occurs in certain tissue, organ, and sub-cellular locations that are controlled by the microenvironment of the location and also by the addition of exogenous agents. In another embodiment, the invention includes compositions containing biologically active compounds and compounds of the general structure: Axe2x80x94Bxe2x80x94C wherein A is a membrane active compound, B is a labile linkage, and C is a compound that inhibits the membrane activity of compound A. The biologically-active compounds include pharmaceutical drugs, nucleic acids and genes. In yet another embodiment, these compounds that are of the general structure xe2x80x94Axe2x80x94Bxe2x80x94C wherein A is a membrane active compound, B is a labile linkage, and C is a compound that inhibits the membrane activity of compound Axe2x80x94 are used to deliver biologically active compounds that include pharmaceutical drugs, nucleic acids and genes. In one specific embodiment, these Axe2x80x94Bxe2x80x94C compounds are used to deliver nucleic acids and genes to muscle (skeletal, heart, respiratory, striated, and non-striated), liver (hepatocytes), spleen, immune cells, gastrointestinal cells, cells of the nervous system (neurons, glial, and microglial), skin cells (dermis and epidermis), joint and synovial cells, tumor cells, kidney, cells of the immune system (dendiritic, T cells, B cells, antigen-presenting cells, macrophages), exocrine cells (pancreas, salivary glands), prostate, adrenal gland, thyroid gland, eye structures (retinal cells), and respiratory cells (cells of the lung, nose, respiratory tract)
Mixtures of Membrane Active Compounds and Labile Compounds
In addition, the invention is a composition of matter that includes a membrane active compound and a labile compound. In one embodiment, the labile compound inhibits the membrane activity of the membrane active compound. Upon chemical modification of the labile compound, membrane activity is restored to the membrane active compound. This chemical modification occurs in certain tissue, organ, and sub-cellular locations that are controlled by the microenvironment of the location and also by the addition of exogenous agents. In one embodiment the chemical modification involves the cleavage of the polymer. In one embodiment, the membrane active compound and the inhibitory labile compound are polyions and are of opposite charge. For example, the membrane active compound is a polycation and the inhibitory labile compound is a polyanion.
In another embodiment, the invention includes compositions containing biologically active compounds, a membrane active compound and a labile compound. Upon chemical modification of the labile compound, membrane activity is restored to the membrane active compound. This chemical modification . occurs in certain tissue, organ, and sub-cellular locations that are controlled by the microenvironment of the location and also by the addition of exogenous agents. In one embodiment the chemical modification involves the cleavage of the polymer. In one specific embodiment, these compositions containing biologically active compounds, a membrane active compound and a labile compound are used to deliver nucleic acids and genes to muscle (skeletal, heart, respiratory, striated, and non-striated), liver (hepatocytes), spleen, immune cells, gastrointestinal cells, cells of the nervous system (neurons, glial, and microglial), skin cells (dermis and epidermis), joint and synovial cells, tumor cells, kidney, cells of the immune system (dendritic, T cells, B cells, antigen-presenting cells, macrophages), exocrine cells (pancreas, salivary glands), prostate, adrenal gland, thyroid gland, eye structures (retinal cells), respiratory cells (cells of the lung, nose, respiratory tract), and endothelial cells.
Biologically active compounds Containing pH-labile and/or Extremely and/or Very pH-Labile Bonds
The invention specifies compounds of the following general structure: Axe2x80x94Bxe2x80x94C wherein A is a biologically active compound such as pharmaceuticals, drugs, proteins, peptides, hormones, cytokines, enzymes and nucleic acids such as anti-sense, ribozyme, recombining nucleic acids, and expressed genes; B is a labile linkage that contains a pH-labile bond such as acetals, ketals, enol ethers, enol esters, amides of 2,3-disubstituted maleamic acids, imines, imminiums, enamines, silyl ethers, and silyl enol ethers; and C is a compound. In one embodiment C is a compound that modifies the activity, function, delivery, transport, shelf-life, pharmacokinetics, blood circulation time in vivo, tissue and organ targetting, and sub-cellular targeting of the biologically active compound A. For example, C can be a hydrophilic compound such as polyethylene glycol to increase the water solubility of relatively hydrophobic drugs (e.g. amphotericin B) to improve their formulation and delivery properties. In other embodiments, B is a labile linkage that contains pH-labile bond such as acetals, ketals, enol ethers, enol esters, amides, imines, imminiums, enamines, silyl ethers, and silyl enol ethers.
The invention also specifies that the labile linkage B is attached to reactive functional groups on the biologically active compound A. In yet another embodiment, reactive functional groups are attached to nucleic acids via alkylation. Specifically, nitrogen and sulfur mustards may be used for modify nucleic acids with reactive functional groups.
pH-Labile Amphipathic Compounds
In one specification of the invention, the pH-labile and very pH-labile linkages and bonds are used within amphipathic compounds and detergents. The pH-labile amphipathic compounds can be incorporated into liposomes for delivery of biologically active compounds and nucleic acids to cells. The detergents can be used for cleaning purposes and for modifying the solubility of biologically active compounds such as proteins. The detergents can be in the form of micelles or reverse micelles. Often detergents are used to extract biologically active compounds from natural mixtures. After the extraction procedure is completed, a labile detergent would aid in the separation of the detergent and the biologically active compound. If the detergent is labile under conditions that do not harm the biologically active compound (e.g. destroying or denaturing a protein), then removal of the detergent would be much easier that currently-used methods.
To facilitate an understanding of the present invention, a number of terms and phrases are defined below:
Biologically active compound
A biologically active compound is a compound having the potential to react with biological components. More particularly, biologically active compounds utilized in this specification are designed to change the natural processes associated with a living cell. For purposes of this specification, a cellular natural process is a process that is associated with a cell before delivery of a biologically active compound. In this specification, the cellular production of, or inhibition of a material, such as a protein, caused by a human assisting a molecule to an in vivo cell is an example of a delivered biologically active compound. Pharmaceuticals, proteins, peptides, polypeptides, enzyme inhibitors, hormones, cytokines, antigens, viruses, oligonucleotides, enzymes and nucleic acids are examples of biologically active compounds.
Peptide and polypeptide refer to a series of amino acid residues, more than two, connected to one another by amide bonds between the beta or alpha-amino group and carboxyl group of contiguous amino acid residues. The amino acids may be naturally occurring or synthetic. Polypeptide includes proteins and peptides, modified proteins and peptides, and non-natural proteins and peptides. Enzymes are proteins evolved by the cells of living organisms for the specific function of catalyzing chemical reactions. A chemical reaction is defined as the formation or cleavage of covalent or ionic bonds. Bioactive compounds may be used interchangeably with biologically active compound for purposes of this application.
Delivery of Biologically active compound
The delivery of a biologically active compound is commonly known as xe2x80x9cdrug deliveryxe2x80x9d. xe2x80x9cDeliveredxe2x80x9d means that the biologically active compound becomes associated with the cell or organism. The compound can be in the circulatory system, intravessel, extracellular, on the membrane of the cell or inside the cytoplasm, nucleus, or other organelle of the cell.
Parenteral routes of administration include intravascular (intravenous, intraarterial), intramuscular, intraparenchymal, intradermal, subdermal, subcutaneous, intratumor, intraperitoneal, intrathecal, subdural, epidural, and intralymphatic injections that use a syringe and a needle or catheter. An intravascular route of administration enables a polymer or polynucleotide to be delivered to cells more evenly distributed and more efficiently expressed than direct injections. Intravascular herein means within a tubular structure called a vessel that is connected to a tissue or organ within the body. Within the cavity of the tubular structure, a bodily fluid flows to or from the body part. Examples of bodily fluid include blood, cerebrospinal fluid (CSF), lymphatic fluid, or bile. Examples of vessels include arteries, arterioles, capillaries, venules, sinusoids, veins, lymphatics, and bile ducts. The intravascular route includes delivery through the blood vessels such as an artery or a vein. An administration route involving the mucosal membranes is meant to include nasal, bronchial, inhalation into the lungs, or via the eyes. Other routes of administration include intraparenchymal into tissues such as muscle (intramuscular), liver, brain, and kidney. Transdermal routes of administration have been effected by patches and ionotophoresis. Other epithelial routes include oral, nasal, respiratory, and vaginal routes of administration.
Delivery System
Delivery system is the means by which a biologically active compound becomes delivered. That is all compounds, including the biologically active compound itself, that are required for delivery and all procedures required for delivery including the form (such volume and phase (solid, liquid, or gas)) and method of administration (such as but not limited to oral or subcutaneous methods of delivery).
Nucleic Acid
The term xe2x80x9cnucleic acidxe2x80x9d is a term of art that refers to a polymer containing at least two nucleotides. xe2x80x9cNucleotidesxe2x80x9d contain a sugar deoxyribose (DNA) or ribose (RNA), a base, and a phosphate group. Nucleotides are linked together through the phosphate groups. xe2x80x9cBasesxe2x80x9d include purines and pyrimidines, which further include natural compounds adenine, thymine, guanine, cytosine, uracil, inosine, and natural analogs, and synthetic derivatives of purines and pyrimidines, which include, but are not limited to, modifications which place new reactive groups such as, but not limited to, amines, alcohols, thiols, carboxylates, and alkylhalides. Nucleotides are the monomeric units of nucleic acid polymers. A xe2x80x9cpolynucleotidexe2x80x9d is distinguished here from an xe2x80x9coligonucleotidexe2x80x9d by containing more than 80 monomeric units; oligonucleotides contain from 2 to 80 nucleotides. The term nuclei acid includes deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The term encompasses sequences that include any of the known base analogs of DNA and RNA including, but not limited to, 4-acetylcytosine, 8-hydroxy-N6-methyladenosine, aziridinylcytosine, pseudoisocytosine, 5-(carboxyhydroxylmethyl)uracil, 5-fluorouracil, 5-bromouracil, 5-carboxymethylaminomethyl-2-thiouracil, 5-carboxymethylaminomethyluracil, dihydrouracil, inosine, N6-isopentenyladenine, 1-methyladenine, 1-methylpseudouracil, 1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2-methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-methyladenine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueosine, 5xe2x80x2-methoxycarbonylmethyluracil, 5-methoxyuracil, 2-methylthio-N6-isopentenyladenine, is uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid, oxybutoxosine, pseudouracil, queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5-methyluracil, N-uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid, pseudouracil, queosine, 2-thiocytosine, and 2,6-diaminopurine.
DNA may be in the form of anti-sense, plasmid DNA, parts of a plasmid DNA, product of a polymerase chain reaction (PCR), vectors (P1, PAC, BAC, YAC, artificial chromosomes), expression cassettes, chimeric sequences, chromosomal DNA, or derivatives of these groups. RNA may be in the form of oligonucleotide RNA, tRNA (transfer RNA), snRNA (small nuclear RNA), rRNA (ribosomal RNA), mRNA (messenger RNA), anti-sense RNA, ribozymes, chimeric sequences, or derivatives of these groups.
xe2x80x9cAnti-sensexe2x80x9d is a polynucleotide that interferes with the function of DNA and/or RNA. This may result in suppression of expression. Natural nucleic acids have a phosphate backbone, artificial nucleic acids may contain other types of backbones and bases. These include PNAs (peptide nucleic acids), phosphothionates, and other variants of the phosphate backbone of native nucleic acids. In addition, DNA and RNA may be single, double, triple, or quadruple stranded.
The term xe2x80x9crecombinant DNA moleculexe2x80x9d as used herein refers to a DNA molecule that is comprised of segments of DNA joined together by means of molecular biological techniques. xe2x80x9cExpression cassettexe2x80x9d refers to a natural or recombinantly produced polynucleotide molecule that is capable of expressing protein(s). A DNA expression cassette typically includes a promoter (allowing transcription initiation), and a sequence encoding one or more proteins. Optionally, the expression cassette may include transcriptional enhancers, non-coding sequences, splicing signals, transcription termination signals, and polyadenylation signals. An RNA expression cassette typically includes a translation initiation codon (allowing translation initiation), and a sequence encoding one or more proteins. Optionally, the expression cassette may include translation termination signals, a polyadenosine sequence, internal ribosome entry sites (IRES), and non-coding sequences.
A nucleic acid can be used to modify the genomic or extrachromosomal DNA sequences. This can be achieved by delivering a nucleic acid that is expressed. Alternatively, the nucleic acid can effect a change in the DNA or RNA sequence of the target cell. This can be achieved by homologous recombination, gene conversion, or other yet to be described mechanisms.
Gene
The term xe2x80x9cgenexe2x80x9d refers to a nucleic acid (e.g., DNA) sequence that comprises coding sequences necessary for the production of a polypeptide or precursor (e.g., -myosin heavy chain). The polypeptide can be encoded by a full length coding sequence or by any portion of the coding sequence so long as the desired activity or functional properties (e.g., enzymatic activity, ligand binding, signal transduction, etc.) of the full-length or fragment are retained. The term also encompasses the coding region of a structural gene and the including sequences located adjacent to the coding region on both the 5xe2x80x2 and 3xe2x80x2 ends for a distance of about 1 kb or more on either end such that the gene corresponds to the length of the full-length mRNA. The sequences that are located 5xe2x80x2 of the coding region and which are present on the mRNA are referred to as 5xe2x80x2 non-translated sequences. The sequences that are located 3xe2x80x2 or downstream of the coding region and which are present on the mRNA are referred to as 3xe2x80x2 non-translated sequences. The term xe2x80x9cgenexe2x80x9d encompasses both cDNA and genomic forms of a gene. A genomic form or clone of a gene contains the coding region interrupted with non-coding sequences termed xe2x80x9cintronsxe2x80x9d or xe2x80x9cintervening regionsxe2x80x9d or xe2x80x9cintervening sequences.xe2x80x9d Introns are segments of a gene which are transcribed into nuclear RNA (hnRNA); introns may contain regulatory elements such as enhancers. Introns are removed or xe2x80x9cspliced outxe2x80x9d from the nuclear or primary transcript; introns therefore are absent in the messenger RNA (mRNA) transcript. The mRNA functions during translation to specify the sequence or order of amino acids in a nascent polypeptide.
As used herein, the terms xe2x80x9cnucleic acid molecule encoding,xe2x80x9d xe2x80x9cDNA sequence encoding,xe2x80x9d and xe2x80x9cDNA encodingxe2x80x9d refer to the order or sequence of deoxyribonucleotides along a strand of deoxyribonucleic acid. The order of these deoxyribonucleotides determines the order of amino acids along the polypeptide (protein) chain. The DNA sequence thus codes for the amino acid sequence.
As used herein, the terms xe2x80x9can oligonucleotide having a nucleotide sequence encoding a genexe2x80x9d and xe2x80x9cpolynucleotide having a nucleotide sequence encoding a gene,xe2x80x9d means a nucleic acid sequence comprising the coding region of a gene or in other words the nucleic acid sequence which encodes a gene product. The coding region may be present in either a cDNA, genomic DNA or RNA form. When present in a DNA form, the oligonucleotide or polynucleotide may be single-stranded or double-stranded. Suitable control elements such as enhancers/promoters, splice junctions, polyadenylation signals, etc. may be placed in close proximity to the coding region of the gene if needed to permit proper initiation of transcription and/or correct processing of the primary RNA transcript. Alternatively, the coding region utilized in the expression vectors of the present invention may contain endogenous enhancers/promoters, splice junctions, intervening sequences, polyadenylation signals, etc. or a combination of both endogenous and exogenous control elements.
The term xe2x80x9cisolatedxe2x80x9d when used in relation to a nucleic acid, as in xe2x80x9can isolated oligonucleotidexe2x80x9d or xe2x80x9cisolated polynucleotidexe2x80x9d refers to a nucleic acid sequence that is identified and separated from at least one contaminant nucleic acid with which it is ordinarily associated in its natural source. Isolated nucleic acid is such present in a form or setting that is different from that in which it is found in nature. In contrast, non-isolated nucleic acids as nucleic acids such as DNA and RNA found in the state they exist in nature. For example, a given DNA sequence (e.g., a gene) is found on the host cell chromosome in proximity to neighboring genes; RNA sequences, such as a specific mRNA sequence encoding a specific protein, are found in the cell as a mixture with numerous other mRNAs that encode a multitude of proteins. However, isolated nucleic acid encoding a given protein includes, by way of example, such nucleic acid in cells ordinarily expressing the given protein where the nucleic acid is in a chromosomal location different from that of natural cells, or is otherwise flanked by a different nucleic acid sequence than that found in nature. The isolated nucleic acid, oligonucleotide, or polynucleotide may be present in single-stranded or double-stranded form.
Gene Expression
As used herein, the term xe2x80x9cgene expressionxe2x80x9d refers to the process of converting genetic information encoded in a gene into RNA (e.g., mRNA, rRNA, tRNA, or snRNA) through xe2x80x9ctranscriptionxe2x80x9d of the gene (i.e., via the enzymatic action of an RNA polymerase), and for protein encoding genes, into protein through xe2x80x9ctranslationxe2x80x9d of mRNA. Gene expression can be regulated at many stages in the process. xe2x80x9cUp-regulationxe2x80x9d or xe2x80x9cactivationxe2x80x9d refers to regulation that increases the production of gene expression products (i.e., RNA or protein), while xe2x80x9cdown-regulationxe2x80x9d or xe2x80x9crepressionxe2x80x9d refers to regulation that decreases production. Molecules (e.g., transcription factors) that are involved in up-regulation or down-regulation are often called xe2x80x9cactivatorsxe2x80x9d and xe2x80x9crepressors,xe2x80x9d respectively.
Delivery of Nucleic Acids
The process of delivering a polynucleotide to a cell has been commonly termed xe2x80x9ctransfectionxe2x80x9d or the process of xe2x80x9ctransfectingxe2x80x9d and also it has been termed xe2x80x9ctransformationxe2x80x9d. The polynucleotide could be used to produce a change in a cell that can be therapeutic. The delivery of polynucleotides or genetic material for therapeutic and research purposes is commonly called xe2x80x9cgene therapyxe2x80x9d. The delivery of nucleic acid can lead to modification of the DNA sequence of the target cell.
The polynucleotides or genetic material being delivered are generally mixed with transfection reagents prior to delivery. The term xe2x80x9ctransfectionxe2x80x9d as used herein refers to the introduction of foreign DNA into eukaryotic cells. Transfection may be accomplished by a variety of means known to the art including calcium phosphate-DNA co-precipitation, DEAE-dextran-mediated transfection, polybrene-mediated transfection, electroporation, microinjection, liposome fusion, lipofection, protoplast fusin, retroviral infection, and biolistics.
The term xe2x80x9cstable transfectionxe2x80x9d or xe2x80x9cstably transfectedxe2x80x9d refers to the introduction and integration of foreign DNA into the genome of the transfected cell. The term xe2x80x9cstable transfectantxe2x80x9d refers to a cell that has irreversibly integrated foreign DNA into the genomic DNA.
The term xe2x80x9ctransient transfectionxe2x80x9d or xe2x80x9ctransiently transfectedxe2x80x9d refers to the introduction of foreign DNA into a cell where the foreign DNA fails to integrate into the genome of the transfected cell. The foreign DNA persists in the nucleus of the transfected cell for several days. During this time the foreign DNA is subject to the regulatory controls that govern the expression of endogenous genes in the chromosomes. The term xe2x80x9ctransient transfectantxe2x80x9d refers to cells that have taken up foreign DNA but have failed to integrate this DNA. The term xe2x80x9cnaked polynucleotidesxe2x80x9d indicates that the polynucleotides are not associated with a transfection reagent or other delivery vehicle that is required for the polynucleotide to be delivered to a cell.
A xe2x80x9ctransfection reagentxe2x80x9d or xe2x80x9cdelivery vehiclexe2x80x9d is a compound or compounds that bind(s) to or complex(es) with oligonucleotides, polynucleotides, or other desired compounds and mediates their entry into cells. Examples of transfection reagents include, but are not limited to, cationic liposomes and lipids, polyamines, calcium phosphate precipitates, histone proteins, polyethylenimine, and polylysine complexes (polyethylenimine and polylysine are both toxic). Typically, when used for the delivery of nucleic acids, the transfection reagent has a net positive charge that binds to the polynucleotide""s negative charge. For example, cationic liposomes or polylysine complexes have net positive charges that enable them to bind to DNA or RNA.
Enzyme
Enzyme is a protein that acts as a catalyst. That is a protein that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. The chemical reactions that are catalyzed by an enzyme are termed enzymatic reactions and chemical reactions that are not are termed nonenzymatic reactions.
Half-life
The half-life of a chemical reaction is the time required for one half of a given material to undergo a chemical reaction.
Complex
Two molecules are combined, to form a complex through a process called complexation or complex formation, if the are in contact with one another through noncovalent interactions such as electrostatic interactions, hydrogen bonding interactions, and hydrophobic interactions.
Modification
A molecule is modified, to form a modification through a process called modification, by a second molecule if the two become bonded through a covalent bond. That is, the two molecules form a covalent bond between an atom form one molecule and an atom from the second molecule resulting in the formation of a new single molecule. A chemical covalent bond is an interaction, bond, between two atoms in which there is a sharing of electron density.
Osmosis
Osmosis is the passage of a solvent through a semipermeable membrane, a membrane through which solvent can pass but not all solutes, separating two solutions of different concentrations. There is a tendency for the separated solutions to become the same concentration as the solvent passes from low concentration to high concentration. Osmosis will stop when the two solutions become equal in concentration or when pressure is applied to the solution containing higher concentration. When the higher concentrated solution is in a closed system, that is when system is of constant volume, there is a build up of pressure as the solvent passes from low to high concentration. This build up of pressure is called osmotic pressure.
Salt
A salt is any compound containing ionic bonds, that is bonds in which one or more electrons are transferred completely from one atom to another.
Interpolyelectrolyte Complexes
An interpolyelectrolyte complex is a noncovalent interaction between polyelectrolytes of opposite charge.
Charge, Polarity, and Sign
The charge, polarity, or sign of a compound refers to whether or not a compound has lost one or more electrons (positive charge, polarity, or sign) or gained one or more electrons (negative charge, polarity, or sign).
Cell Targeting Signals
Cell targeting signal (or abbreviated as the Signal) is defined in this specification as a molecule that modifies a biologically active compounds such as drug or nucleic acid and can direct it to a cell location (such as tissue) or location in a cell (such as the nucleus) either in culture or in a whole organism. By modifying the cellular or tissue location of the foreign gene, the function of the biologically active compound can be enhanced.
The cell targeting signal can be a protein, peptide, lipid, steroid, sugar, carbohydrate, (non-expressing) polynucleic acid or synthetic compound. The cell targeting signal enhances cellular binding to receptors, cytoplasmic transport to the nucleus and nuclear entry or release from endosomes or other intracellular vesicles.
Nuclear localizing signals enhance the targeting of the pharmaceutical into proximity of the nucleus and/or its entry into the nucleus. Such nuclear transport signals can be a protein or a peptide such as the SV40 large T ag NLS or the nucleoplasmin NLS. These nuclear localizing signals interact with a variety of nuclear transport factors such as the NLS receptor (karyopherin alpha) which then interacts with karyopherin beta. The nuclear transport proteins themselves could also function as NLS""s since they are targeted to the nuclear pore and nucleus. For example, karyopherin beta itself could target the DNA to the nuclear pore complex. Several peptides have been derived from the SV40 T antigen. These include a short NLS (H-SEQ ID NO: 1-OH) or long NLS""s (H-SEQ ID NO: 3-OH and H-SEQ ID NO: 4-OH). Other NLS peptides have been derived from M9 protein (SEQ ID NO: 5), E1A (H-SEQ ID NO: 6-OH), nucleoplasmin (H-SEQ ID NO: 7-OH), and c-myc (H-SEQ ID NO: 8-OH).
Signals that enhance release from intracellular compartments (releasing signals) can cause DNA release from intracellular compartments such as endosomes (early and late), lysosomes, phagosomes, vesicle, endoplasmic reticulum, golgi apparatus, trans golgi network (TGN), and sarcoplasmic reticulum. Release includes movement out of an intracellular compartment into cytoplasm or into an organelle such as the nucleus. Releasing signals include chemicals such as chloroquine, bafilomycin or Brefeldin A1 and the ER-retaining signal (SEQ ID NO: 9 sequence), viral components such as influenza virus hemagglutinin subunit HA-2 peptides and other types of amphipathic peptides.
Cellular receptor signals are any signal that enhances the association of the biologically active compound with a cell. This can be accomplished by either increasing the binding of the compound to the cell surface and/or its association with an intracellular compartment, for example: ligands that enhance endocytosis by enhancing binding the cell surface. This includes agents that target to the asialoglycoprotein receptor by using asiologlycoproteins or galactose residues. Other proteins such as insulin, EGF, or transferrin can be used for targeting. Peptides that include the RGD sequence can be used to target many cells. Chemical groups that react with thiol, sulfhydryl, or disulfide groups on cells can also be used to target many types of cells. Folate and other vitamins can also be used for targeting. Other targeting groups include molecules that interact with membranes such as lipids, fatty acids, cholesterol, dansyl compounds, and amphotericin derivatives. In addition viral proteins could be used to bind cells.
Interaction Modifiers
An interaction modifier changes the way that a molecule interacts with itself or other molecules, relative to molecule containing no interaction modifier. The result of this modification is that self-interactions or interactions with other molecules are either increased or decreased. For example cell targeting signals are interaction modifiers with change the interaction between a molecule and a cell or cellular component. Polyethylene glycol is an interaction modifier that decreases interactions between molecules and themselves and with other molecules.
Reporter or Marker Molecules
Reporter or marker molecules are compounds that can be easily detected. Typically they are fluorescent compounds such as fluorescein, rhodamine, Texas red, cy 5, cy 3 or dansyl compounds. They can be molecules that can be detected by infrared, ultraviolet or visible spectroscopy or by antibody interactions or by electron spin resonance. Biotin is another reporter molecule that can be detected by labeled avidin. Biotin could also be used to attach targeting groups.
Linkages
An attachment that provides a covalent bond or spacer between two other groups (chemical moieties). The linkage may be electronically neutral, or may bear a positive or negative charge. The chemical moieties can be hydrophilic or hydrophobic. Preferred spacer groups include, but are not limited to C1-C12 alkyl, C1-C12 alkenyl, C1-C12 alkynyl, C6-C18 aralkyl, C6-C18 aralkenyl, C6-C18 aralkynyl, ester, ether, ketone, alcohol, polyol, amide, amine, polyglycol, polyether, polyamine, thiol, thio ether, thioester, phosphorous containing, and heterocyclic.
Bifunctional
Bifunctional molecules, commonly referred to as crosslinkers, are used to connect two molecules together, i.e. form a linkage between two molecules. Bifunctional molecules can contain homo or heterobifunctionality.
Crosslinking
Crosslinking refers to the chemical attachment of two or more molecules with a bifunctional reagent. A bifunctional reagent is a molecule with two reactive ends. The reactive ends can be identical as in a homobifunctional molecule, or different as in a heterobifunctional molecule.
Labile Bond
A labile bond is a covalent bond that is capable of being selectively broken. That is, the labile bond may be broken in the presence of other covalent bonds without the breakage of other covalent bonds. For example, a disulfide bond is capable of being broken in the presence of thiols without cleavage of any other bonds, such as carbon-carbon, carbon-oxygen, carbon-sulfur, carbon-nitrogen bonds, which may also be present in the molecule.
Labile Linkage
A labile linkage is a chemical compound that contains a labile bond and provides a link or spacer between two other groups. The groups that are linked may be chosen from compounds such as biologically active compounds, membrane active compounds, compounds that inhibit membrane activity, functional reactive groups, monomers, and cell targeting signals. The spacer group may contain chemical moieties chosen from a group that includes alkanes, alkenes, esters, ethers, glycerol, amide, saccharides, polysaccharides, and heteroatoms such as oxygen, sulfur, or nitrogen. The spacer may be electronically neutral, may bear a positive or negative charge, or may bear both positive and negative charges with an overall charge of neutral, positive or negative.
pH-Labile Linkages and Bonds
pH-labile refers to the selective breakage of a covalent bond under acidic conditions (pH less than 7). That is, the pH-labile bond may be broken under acidic conditions in the presence of other covalent bonds without their breakage. The term pH-labile includes both linkages and bonds that are pH-labile, very pH-labile, and extremely pH-abile.
Very pH-Labile Linkages and Bonds
A subset of pH-labile bonds is very pH-labile. For the purposes of the present invention, a bond is considered very pH-labile if the half-life for cleavage at pH 5 is less than 45 minutes.
Extremely pH-Labile Linkages and Bonds
A subset of pH-labile bonds is extremely pH-labile. For the purposes of the present invention, a bond is considered extremely pH-labile if the half-life for cleavage at pH 5 is less than 15 minutes.
Amphiphilic and Amphipathic Compounds
Amphipathic, or amphiphilic, compounds have both hydrophilic (water-soluble) and hydrophobic (water-insoluble) parts. Hydrophilic groups indicate in qualitative terms that the chemical moiety is water-preferring. Typically, such chemical groups are water soluble, and are hydrogen bond donors or acceptors with water. Examples of hydrophilic groups include compounds with the following chemical moieties; carbohydrates, polyoxyethylene, peptides, oligonucleotides and groups containing amines, amides, alkoxy amides, carboxylic acids, sulfurs, or hydroxyls. Hydrophobic groups indicate in qualitative terms that the chemical moiety is water-avoiding. Typically, such chemical groups are not water soluble, and tend not to hydrogen bonds. Hydrocarbons are hydrophobic groups.
Detergent
Detergents or surfactants are water-soluble molecules containing a hydrophobic portion (tail) and a hydrophilic portion (head), which upon addition to water decrease water""s surface tension. The hydrophobic portion can be alkyl, alkenyl, alkynyl or aromatic. The hydrophilic portion can be charged with either net positive (cationic detergents), negative (anionic detergents), uncharged (nonionic detergents), or charge neutral (zwitterionic detergent). Examples of anionic detergents are sodium dodecyl sulfate, glycolic acid ethoxylate(4 units) 4-tert-butylphenylether, palmitic acid, and oleic acid. Examples of cationic detergents are cetyltrimethylammonium bromide and oleylamine. Examples of nonionic detergents include, laurylmaltoside, Triton X-100, and Tween. Examples of zwitterionic detergents include 3-[(3-cholamidopropyl)dimthylammonio]1-propane-sulfonate (CHAPS), and N-tetradecyl-N,N-dimethyl-3-ammoniu-1-propanesulfonate.
Surface Tension
The surface tension of a liquid is the force acting over the surface of the liquid per unit length of surface that is perpendicular to the force that is acting of the surface. Surface charge has the units force per length, e.g. Newtons/meter.
Membrane Active Compound
Membrane active agents or compounds are compounds (typically a polymer, peptide or protein) that are able alter the membrane structure. This change in structure can be shown by the compound inducing one or more of the following effects upon a membrane: an alteration that allows small molecule permeability, pore formation in the membrane, a fusion and/or fission of membranes, an alteration that allows large molecule permeability, or a dissolving of the membrane. This alteration can be functionally defined by the compound""s activity in at least one the following assays: red blood cell lysis (hemolysis), liposome leakage, liposome fusion, cell fusion, cell lysis and endosomal release. An example of a membrane active agent in our examples is the peptide melittin, whose membrane activity is demonstrated by its ability to release heme from red blood cells (hemolysis). In addition, dimethylmaleamic-modified melittin(DM-Mel) reverts to melittin in the acidic environment of the endosome causes endosomal release as seen by the diffuse staining of fluorescein-labeled dextran in our endosomal release assay.
More specifically membrane active compounds allow for the transport of molecules with molecular weight greater than 50 atomic mass units to cross a membrane. This transport may be accomplished by either the total loss of membrane structure, the formation of holes (or pores) in the membrane structure, or the assisted transport of compound through the membrane. In addition, transport between liposomes, or cell membranes, may be accomplished by the fusion of the two membranes and thereby the mixing of the contents of the two membranes.
Membrane active peptides.
Membrane active peptides are peptides that have membrane activity. There are many naturally occurring membrane active peptides such as cecropin (insects), magainin, CPF 1, PGLa, Bombinin BLP-1 (all three from amphibians), melittin (bees), seminalplasmin (bovine), indolicidin, bactenecin (both from bovine neutrophils), tachyplesin 1 (crabs), protegrin (porcine leukocytes), and defensins (from human, rabbit, bovine, fungi, and plants). Gramicidin A and gramicidin S (bacillus brevis), the lantibiotics such as nisin (lactococcus lactis), androctonin (scorpion), cardiotoxin I (cobra), caerin (frog litoria splendida), dermaseptin (frog). Viral peptides have also been shown to have membrane activity, examples include hemagglutinin subunit HA-2 (influenza virus), E1 (Semliki forest virus), F1 (Sendai and measles viruses), gp41 (HIV), gp32 (SIV), and vp1 (Rhino, polio, and coxsackie viruses). In addition synthetic peptides have also been shown to have membrane activity. Synthetic peptides that are rich in leucines and lysines (KL or KLn motif) have been shown to have membrane activity. In particular, the peptide H2N-SEQ ID NO: 10 CO2, termed KL3, is membrane active.
Compounds or Chemical Groups (Moieties) that Inhibit or Block the Membrane Activity of Another Compound or Chemical Moiety
An interaction with a membrane active agent by modification or complexation (including covalent, ionic, hydrogen bonding, coordination, and van der Waals bonds) with another compound that causes a reduction, or cessation of the said agents membrane activity. Examples include the covalent modification of a membrane-active peptide by the covalent attachment of an inhibitory chemical group (moiety) to the membrane active peptide. Another example includes the interpolyelectrolyte complexation of a membrane active polyanion and inhibitory polycation.
Polymers
A polymer is a molecule built up by repetitive bonding together of smaller units called monomers. In this application the term polymer includes both oligomers which have two to about 80 monomers and polymers having more than 80 monomers. The polymer can be linear, branched network, star, comb, or ladder types of polymer. The polymer can be a homopolymer in which a single monomer is used or can be copolymer in which two or more monomers are used. Types of copolymers include alternating, random, block and graft.
The main chain of a polymer is composed of the atoms whose bonds are required for propagation of polymer length. For example in poly-L-lysine, the carbonyl carbon, xcex1-carbon, and xcex1-amine groups are required for the length of the polymer and are therefore main chain atoms. The side chain of a polymer is composed of the atoms whose bonds are not required for propagation of polymer length. For example in poly-L-lysine, the xcex2, xcex3, xcex4, and xcex5-carbons, and xcex5-nitrogen are not required for the propagation of the polymer and are therefore side chain atoms.
To those skilled in the art of polymerization, there are several categories of polymerization processes that can be utilized in the described process. The polymerization can be chain or step. This classification description is more often used that the previous terminology of addition and condensation polymer. xe2x80x9cMost step-reaction polymerizations are condensation processes and most chain-reaction polymerizations are addition processesxe2x80x9d (M. P. Stevens Polymer Chemistry: An Introduction New York Oxford University Press 1990). Template polymerization can be used to form polymers from daughter polymers. Step Polymerization:
In step polymerization, the polymerization occurs in a stepwise fashion. Polymer growth occurs by reaction between monomers, oligomers and polymers. No initiator is needed since there is the same reaction throughout and there is no termination step so that the end groups are still reactive. The polymerization rate decreases as the functional groups are consumed. Typically, step polymerization is done either of two different ways. One way, the monomer has both reactive functional groups (A and B) in the same molecule so that
Axe2x80x94B yields xe2x80x94[Axe2x80x94B]xe2x80x94
Or the other approach is to have two difunctional monomers.
Axe2x80x94A+Bxe2x80x94B yields xe2x80x94[Axe2x80x94Axe2x80x94Bxe2x80x94B]xe2x80x94
Generally, these reactions can involve acylation or alkylation. Acylation is defined as the introduction of an acyl group (xe2x80x94COR) onto a molecule. Alkylation is defined as the introduction of an alkyl group onto a molecule.
If functional group A is an amine then B can be (but not restricted to) an isothiocyanate, isocyanate, acyl azide, N-hydroxysuccinimide, sulfonyl chloride, aldehyde (including formaldehyde and glutaraldehyde), ketone, epoxide, carbonate, imidoester, carboxylate, or alkylphosphate, arylhalides (difluoro-dinitrobenzene), anhydrides or acid halides, p-nitrophenyl esters, o-nitrophenyl pentachlorophenyl esters, or pentafluorophenyl esters. In other terms when function A is an amine then function B can be acylating or alkylating agent or amination.
If functional group A is a thiol, sulfhydryl, then function B can be (but not restricted to) an iodoacetyl derivative, maleimide, aziridine derivative, acryloyl derivative, fluorobenzene derivatives, or disulfide derivative (such as a pyridyl disulfide or 5-thio-2-nitrobenzoic acid{TNB} derivatives).
If functional group A is carboxylate then function B can be (but not restricted to) a diazoacetate or an amine in which a carbodiimide is used. Other additives may be utilized such as carbonyldiimidazole, dimethylaminopyridine, N-hydroxysuccinimide or alcohol using carbodiimide and dimethylaminopyridine.
If functional group A is a hydroxyl then function B can be (but not restricted to) an epoxide, oxirane, or an amine in which carbonyldiimidazole or N,Nxe2x80x2-disuccinimidyl carbonate, or N-hydroxysuccinimidyl chloroformate or other chloroformates are used.
If functional group A is an aldehyde or ketone then function B can be (but not restricted to) an hydrazine, hydrazide derivative, amine (to form a imine or iminium that may or may not be reduced by reducing agents such as NaCNBH3) or hydroxyl compound to form a ketal or acetal.
Yet another approach is to have one difunctional monomer so that
Axe2x80x94A plus another agent yields xe2x80x94[Axe2x80x94A]xe2x80x94.
If function A is a thiol, sulfhydryl, group then it can be converted to disulfide bonds by oxidizing agents such as iodine (I2) or NalO4 (sodium periodate), or oxygen (O2). Function A can also be an amine that is converted to a thiol, sulfhydryl, group by reaction with 2-Iminothiolate (Traut""s reagent) which then undergoes oxidation and disulfide formation. Disulfide derivatives (such as a pyridyl disulfide or 5-thio-2-nitrobenzoic acid{TNB} derivatives) can also be used to catalyze disulfide bond formation.
Functional group A or B in any of the above examples could also be a photoreactive group such as aryl azides, halogenated aryl azides, diazo, benzophenones, alkynes or diazirine derivatives.
Reactions of the amine, hydroxyl, thiol, sulfhydryl, carboxylate groups yield chemical bonds that are described as amide, amidine, disulfide, ethers, esters, enamine, urea, isothiourea, isourea, sulfonamide, carbamate, carbon-nitrogen double bond (imine), alkylamine bond (secondary amine), carbon-nitrogen single bonds in which the carbon contains a hydroxyl group, thio-ether, diol, hydrazone, diazo, or sulfone.
Chain Polymerization
In chain-reaction polymerization growth of the polymer occurs by successive addition of monomer units to limited number of growing chains. The initiation and propagation mechanisms are different and there is usually a chain-terminating step. The polymerization rate remains constant until the monomer is depleted.
Monomers containing vinyl, acrylate, methacrylate, acrylamide, methacrylamide groups can undergo chain reaction, which can be radical, anionic, or cationic. Chain polymerization can also be accomplished by cycle or ring opening polymerization. Several different types of free radical initiatiors could be used that include peroxides, hydroxy peroxides, and azo compounds such as 2,2xe2x80x2-Azobis(-amidinopropane)dihydrochloride (AAP). A compound is a material made up of two or more elements.
Types of Monomers
A wide variety of monomers can be used in the polymerization processes. These include positive charged organic monomers such as amines, imidine, guanidine, imine, hydroxylamine, hydrazine, heterocycles (like imidazole, pyridine, morpholine, pyrimidine, or pyrene. The amines could be pH-sensitive in that the pKa of the amine is within the physiologic range of 4 to 8. Specific amines include spermine, spermidine, N,Nxe2x80x2-bis(2-aminoethyl)-1,3-propanediamine (AEPD), and 3,3xe2x80x2-Diamino-N,N-dimethyldipropylammonium bromide.
Monomers can also be hydrophobic, hydrophilic or amphipathic. Monomers can also be intercalating agents such as acridine, thiazole organge, or ethidium bromide.
Other Components of the Monomers and Polymers
The polymers have other groups that increase their utility. These groups can be incorporated into monomers prior to polymer formation or attached to the polymer after its formation. These groups include: Targeting Groupsxe2x80x94such groups are used for targeting the polymer-nucleic acid complexes to specific cells or tissues. Examples of such targeting agents include agents that target to the asialoglycoprotein receptor by using asiologlycoproteins or galactose residues. Other proteins such as insulin, EGF, or transferrin can be used for targeting. Protein refers to a molecule made up of 2 or more amino acid residues connected one to another as in a polypeptide. The amino acids may be naturally occurring or synthetic. Peptides that include the RGD sequence can be used to target many cells. Chemical groups that react with thiol, sulfhydryl, or disulfide groups on cells can also be used to target many types of cells. Folate and other vitamins can also be used for targeting. Other targeting groups include molecules that interact with membranes such as fatty acids, cholesterol, dansyl compounds, and amphotericin derivatives.
After interaction of the supramolecular complexes with the cell, other targeting groups can be used to increase the delivery of the drug or nucleic acid to certain parts of the cell. For example, agents can be used to disrupt endosomes and a nuclear localizing signal (NLS) can be used to target the nucleus.
A variety of ligands have been used to target drugs and genes to cells and to specific cellular receptors. The ligand may seek a target within the cell membrane, on the cell membrane or near a cell. Binding of ligands to receptors typically initiates endocytosis. Ligands could also be used for DNA delivery that bind to receptors that are not endocytosed. For example peptides containing RGD peptide sequence that bind integrin receptor could be used. In addition viral proteins could be used to bind the complex to cells. Lipids and steroids could be used to directly insert a complex into cellular membranes.
The polymers can also contain cleavable groups within themselves. When attached to the targeting group, cleavage leads to reduce interaction between the complex and the receptor for the targeting group. Cleavable groups include but are not restricted to disulfide bonds, diols, diazo bonds, ester bonds, sulfone bonds, acetals, ketals, enol ethers, enol esters, enamines and imines.
Polyelectrolyte
A polyelectrolyte, or polyion, is a polymer possessing charge, i.e. the polymer contains a group (or groups) that has either gained or lost one or more electrons. A polycation is a polyelectrolyte possessing net positive charge, for example poly-L-lysine hydrobromide. The polycation can contain monomer units that are charge positive, charge neutral, or charge negative, however, the net charge of the polymer must be positive. A polycation also can mean a non-polymeric molecule that contains two or more positive charges. A polyanion is a polyelectrolyte containing a net negative charge. The polyanion can contain monomer units that are charge negative, charge neutral, or charge positive, however, the net charge on the polymer must be negative. A polyanion can also mean a non-polymeric molecule that contains two or more negative charges. The term polyelectrolyte includes polycation, polyanion, zwitterionic polymers, and neutral polymers. The term zwitterionic refers to the product (salt) of the reaction between an acidic group and a basic group that are part of the same molecule.
Chelator
A chelator is a polydentate ligand, a molecule that can occupy more than one site in the coordination sphere of an ion, particularly a metal ion, primary amine, or single proton. Examples of chelators include crown ethers, cryptates, and non-cyclic polydentate molecules. A crown ether is a cyclic polyether containing (xe2x80x94Xxe2x80x94(CR1-2)n)m units, where n=1-3 and m=3-8. The X and CR1-2 moieties can be substituted, or at a different oxidation states. X can be oxygen, nitrogen, or sulfur, carbon, phosphorous or any combination thereof. R can be H, C, O, S, N, P. A subset of crown ethers described as a cryptate contain a second (xe2x80x94Xxe2x80x94CR1-2)n)z strand where z=3-8. The beginning X atom of the strand is an X atom in the (xe2x80x94Xxe2x80x94(CR1-2)n)m unit, and the terminal CH2 of the new strand is bonded to a second X atom in the (xe2x80x94Xxe2x80x94(CR1-2)n)m unit. Non-cyclic polydentate molecules containing (xe2x80x94Xxe2x80x94CR1-2)n)m unit(s), where n=1-4 and m=1-8. The X and CR1-2 moieties can be substituted, or at a different oxidation states. X can be oxygen, nitrogen, or sulfur, carbon, phosphorous or any combination thereof.
Polychelator
A polychelator is a polymer associated with a plurality of chelators by an ionic or covalent bond and can include a spacer. The polymer can be cationic, anionic, zwitterionic, neutral, or contain any combination of cationic, anionic, zwitterionic, or neutral groups with a net charge being cationic, anionic or neutral, and may contain steric stabilizers, peptides, proteins, signals, or amphipathic compound for the formation of micellar, reverse micellar, or unilamellar structures. Preferably the amphipathic compound can have a hydrophilic segment that is cationic, anionic, or zwitterionic, and can contain polymerizable groups, and a hydrophobic segment that can contain a polymerizable group.
Steric Stabilizer
A steric stabilizer is a long chain hydrophilic group that prevents aggregation of final polymer by sterically hindering particle to particle electrostatic interactions. Examples include: alkyl groups, PEG chains, polysaccharides, hydrogen molecules, alkyl amines. Electrostatic interactions are the non-covalent association of two or more substances due to attractive forces between positive and negative charges.
Buffers
Buffers are made from a weak acid or weak base and their salts. Buffer solutions resist changes in pH when additional acid or base is added to the solution.
Biological, Chemical, or Biochemical reactions
Biological, chemical, or biochemical reactions involve the formation or cleavage of ionic and/or covalent bonds.
Reactive
A compound is reactive if it is capable of forming either an ionic or a covalent bond with another compound. The portions of reactive compounds that are capable of forming covalent bonds are referred to as reactive functional groups.
Lipids
Lipids are compounds that are insoluble in water but soluble in organic solvent which have the general structure composed of two distinct hydrophobic sections, that is two separate sections of uninterrupted carbon-carbon bonds. The two hydrophobic sections are connected through a linkage that contains at least one heteroatom, that is an atom that is not carbon (e.g. nitrogen, oxygen, silicon, and sulfur). Examples include esters and amides of fatty acids and include the glycerides (1,2-dioleoylglycerol (DOG)), glycolipids, phospholipids (dioleoylphosphatidylethanolamine (DOPE)).
Hydrocarbon
Hydrocarbon means containing carbon and hydrogen atoms; and halohydrocarbon means containing carbon, halogen (F, Cl, Br, I), and hydrogen atoms.
Alkyl, alkene, alkyne, aryl
Alkyl means any sp3-hybridized carbon-containing group; alkenyl means containing two or more sp2 hybridized carbon atoms; aklkynyl means containing two or more sp hybridized carbon atoms; aralkyl means containing one or more aromatic ring(s) in addition is containing sp3 hybridized carbon atoms; aralkenyl means containing one or more aromatic ring(s) in addition to containing two or more sp2 hybridized carbon atoms; aralkynyl means containing one or more aromatic ring(s) in addition to containing two or more sp hybridized carbon atoms; steroid includes natural and unnatural steroids and steroid derivatives.
Steroid
A steroid derivative means a sterol, a sterol in which the hydroxyl moiety has been modified (for example, acylated), or a steroid hormone, or an analog thereof. The modification can include spacer groups, linkers, or reactive groups.
Carbohydrate
Carbohydrates include natural and unnatural sugars (for example glucose), and sugar derivatives (a sugar derivative means a system in which one or more of the hydroxyl groups on the sugar moiety has been modified (for example, but not limited to, acylated), or a system in which one or more of the hydroxyl groups is not present).
Polyoxyethylene
Polyoxyethylene means a polymer having ethylene oxide units (xe2x80x94(CH2CH2O)nxe2x80x94, where n=2-3000).
Compound
A compound is a material made up of two or more elements.
Electron Withdrawing and Donating Groups
Electron withdrawing group is any chemical group or atom composed of electronegative atom(s), that is atoms that tend to attract electrons. Electron donating group is any chemical group or atom composed of electropositive atom(s), that is atoms that tend to attract electrons.
Resonance Stabilization
Resonance stabilization is the ability to distribute charge on multiple atoms through pi bonds. The inductive effective, in a molecule, is a shift of electron density due to the polarization of a bond by a nearby electronegative or electropositive atom.
Sterics
Steric hindrance, or sterics, is the prevention or retardation of a chemical reaction because of neighboring groups on the same molecule.
Activated Carboxylate
An activated carboxylate is a carboxylic acid derivative that reacts with nucleophiles to form a new covalent bond. Nucleophiles include nitrogen, oxygen and sulfur-containing compounds to produce ureas, amides, carbonates, carbamates, esters, and thioesters. The carboxylic acid may be activated by various agents including carbodiimides, carbonates, phosphoniums, and uroniums to produce activated carboxylates acyl ureas, acylphosphonates, acid anhydrides, and carbonates. Activation of carboxylic acid may be used in conjunction with hydroxy and amine-containing compounds to produce activated carboxylates N-hydroxysuccinimide esters, hydroxybenzotriazole esters, N-hydroxy-5-norbornene-endo-2,3-dicarboximide esters, p-nitrophenyl esters, pentafluorophenyl esters, 4-dimethylaminopyridinium amides, and acyl imidazoles.
Nucleophile
A nucleophile is a species possessing one or more electron-rich sites, such as an unshared pair of electrons, the negative end of a polar bond, or pi electrons.
Cleavage and Bond Breakage
Cleavage, or bond breakage is the loss of a covalent bond between two atoms. Cleavable means that a bond is capable of being cleaved.
Substituted Group or Substitution
A substituted group or a substitution refers to chemical group that is placed onto a parent system instead of a hydrogen atom. For the compound methylbenzene (toluene), the methyl group is a substituted group, or substitution on the parent system benzene. The methyl groups on 2,3-dimethylmaleic anhydride are substituted groups, or substitutions on the parent compound (or system) maleic anhydride.
Primary and Secondary Amine
A primary amine is a nitrogen-containing compound that is derived by monosubstitution of ammonia (NH3) by a carbon-containing group. A primary amine is a nitrogen-containing compound that is derived by disubstitution of ammonia (NH3) by a carbon-containing group. | {
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This invention relates to the production of a transparent article and, more particularly, to the production of a shaped, transparent thermoplastic article, such as a container or bottle, having an incompatible filler, preferably a gas barrier strengthening filler dispersed therein, wherein the light absorption of the article has been altered to effectively mask or reduce the visual haze of the article.
Thermoplastic polymers, such as polyesters, have long been used in the production of packaging materials, including preforms which are then blown or otherwise oriented into a desired form as necessary for the production of plastic articles such as containers and/or bottles for food and beverage storage and delivery. Among the most preferred and cost-effective thermoplastic polymers used for this purpose are poly(ethylene phthalate) resins. Poly(ethylene terephthalate) (PET), as well as other polyesters, when processed properly under the right conditions and oriented into a desired shape, provides a high clarity, low haze article. Consequently, the plastic bottling industry has used PET and similar polyesters for several years in its production of plastic containers and bottles for food and beverages.
Unfortunately, while plastic containers made from polyester, provide excellent high strength containers having excellent gas barrier properties for most foods and beverages, they are presently not suitable as beer containers or other food containers where extremely low gas permeability is required. It will be appreciated that when oxygen and other air gases come into contact with certain foods and beverages, such as beer for example, the beer oxidizes or otherwise becomes stale. Consequently, attempts have been made heretofore to reduce the oxygen/gas permeability of the container or, stated another way, to increase the gas barrier strength of the container.
One known way to reduce oxygen/gas permeability or to increase the gas barrier strength of the container is to blend certain gas barrier strengthening fillers with the polyester in the container. For instance, certain polyamides, such as polyxylylene amides, are well known in the art to provide improved gas barrier strength to polyester containers. To produce these containers, the filler is typically blended or dispersed in the polyester by processes known in the art and then the article is manufactured. In some instances, the containers may be molded as by injection molding and the like. In other instances, preforms of the containers are prepared such as by injection molding or extrusion, and are then blown or otherwise oriented into the desired size and shape.
Various patents and patent publications have taught the use of polyester/polyamide blend compositions for forming an article having low haze and reduced gas permeability compared to polyester alone. In at least one patent publication, in order to provide a low haze/low gas permeability container, it is stated that the blend composition employ a polyamide having a number average molecular weight of less than 15,000. That patent publication further makes it clear that blends of higher molecular weight polyamides with polyester are known to have high haze values which limit their practical use in the food and beverage container industry.
In other words, heretofore, few, if any, blends of polyester and these gas barrier strengthening fillers, such as higher molecular weight polyamides, have been used in the plastic container or bottling industry, or any industry where transparent, high clarity articles are desired, because it is a well-known fact that, upon orienting or stretching an article containing a blend of polyester and polyamide, the article loses much of its clarity and transparency, i.e., becomes visually cloudy or hazy. This characteristic is known in the industry as haze.
Haze, as described in most of the patent literature, can be measured, much like any other physical property. Measurements to determine the level or amount of haze may be obtained using a colorimeter (e.g., Hunter Lab Color Quest) and following ASTM D1003. Haze is typically reported as a percentage based upon the thickness of the article and can be calculated by the equation
Haze % = T Diffuse T Total × 100 where Haze % equals transmittance haze, TDiffuse equals diffuse light transmittance, and TTotal equals total light transmittance. A 4% haze measurement in a container sidewall approximately 15 mils thick is normally visible to the naked eye. Generally, when testing containers made from different blends of polyester and polyamides, haze values have been measured in the 15% to 35% range for these 15 mil thick containers. For purposes of this invention, this type of haze will often be referred to hereinafter as “physical haze” or “measured haze.”
Moreover, as the amount of gas barrier strengthening filler used in the polyester/filler blend increases, the physical haze value also increases. In fact, it has been found by others that effective blend ratios of polyester (e.g., PET) and aromatic polyamides (e.g., poly(m-xylylene adipamide) commonly referred to as MXD6) provide for physical haze values in the 20% to 30% range upon orienting the polymers into the form of a container again having a wall thickness of about 15 mils.
Heretofore, efforts have focused on reducing the gas permeability of the article by addition of gas barrier strengthening fillers, while, at the same time, trying to reduce the amount of physical haze produced upon orientation of the article. Such efforts, where successful, have generally found that to reduce physical haze, the size of the molecules of the filler had to be significantly small. Generally, it is understood, as stated above, that polyamides having a number average molecular weight of less than 15000 in a concentration of less than 2 percent by weight are needed to sufficiently reduce physical haze. Alternatively, it has been found that, where polyamide domains in the polyester have been limited to an average number size of from 30 to 200 nanometers, physical haze will also be reduced or limited. At least one theory for this phenomenon is that the polyamide particles are so small that they fail to scatter light, particularly in the visible spectra, i.e., the particles do not reflect light to the observer in a manner detectable to the naked eye. Moreover, in measuring the physical haze using machines such as a colorimeter, it is clear that the physical haze measured has been reduced or potentially even eliminated.
Based upon this theory, it should be understood then that, where those particles or domains surrounding the filler are much larger than 200 nanometers, say on the order of 400 to 700 nanometers, the haze of the article is not only physically measurable, but also may be visible to the ordinary observer. In fact, at least one journal article expressly recognizes that the number and size of the dispersed particles does create measured haze. It is further noted therein that stretching makes for even more measured haze because, firstly, stretching increases the size of the dispersed particles in a sheet plane and, secondly, the difference in the anisotropic refractive indices of the matrix and the dispersed phase increases. Thus, some patents have attempted to prevent the stretching or reorienting of the MXD6 domains, for example, by producing bottles of PET and MXD6 when the polymer is in its molten state.
Hence, all of the prior art has focused on the physical haze phenomenon and the reduction or elimination thereof. In contrast, the present invention focuses on the visual aspect of the haze property since it is this characteristic which is believed to be detrimental to the cosmetic appearance and practical use of the article, not the physical haze of the article.
Heretofore, however, this “visual haze” or “visible haze” of an article has never been considered separate and apart from the physical haze of the article, as it is generally immeasurable by traditional physical testing of the article. By “visual haze” or “visible haze,” it is meant that haze which can be observed optically or visually by a person in ordinary direct or indirect light. It is the haze that is visible to the naked eye of the observer, presumably due to the reflectance or transmittance of the light from the filler domains present in the article. It is believed that the visual masking of the physical haze phenomenon results in the elimination or reduction of this “visual haze,” and can provide an article suitable for commercial use. To that end, it will be understood that “visual haze” is not a measured physical property to the same extent that the physical haze of an article is determinable on a colorimeter or the like, and eliminating or reducing visual haze may or may not reduce the measured physical haze of the article.
Accordingly, eliminating or reducing the “visual haze” of an article, regardless of the physical haze measurements, is seen as highly desirable to the art, particularly to the plastic container and bottling industry. Thus, there remains a need to provide a process by which to mask the visible haze of a transparent article made from polyester blended with a gas barrier strengthening filler, as well as for transparent, preferably oriented, articles comprising a polyester/filler blend that is aesthetically and visually acceptable to the plastic container and bottling industry. | {
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The present invention relates generally to afocal optical systems and, more particularly, to methods and apparatus for accurately measuring the magnification of afocal optical systems.
An afocal optical system accepts an input beam of collimated light and creates an output beam that is also collimated. Examples include binoculars, spyglasses, rifle scopes and telescopes. An afocal system does not, by itself, form a final image, and by definition, does not have a finite focal length. However, a comparable first order parameter for such a system is its (afocal) magnification. This is essential to know when combining an afocal optical system with other imaging elements.
Afocal optical instruments, such as binoculars and telescopes are common devices for making a distant object appear larger. It is also quite common to compute the afocal magnifying power of such instruments without independent experimental measurement. The magnification of a simple afocal system can be theoretically computed with knowledge of the individual components and the design of the system, by either using the ratio of the focal lengths of optical components or the ratio of the angles of the incoming and outgoing beams. This approach is consistent with U.S. Pat. No. 4,678,899 to Baba, et al, which discusses a class of variable magnification afocal lens systems where the magnification is changed by moving optical components with respect to each other. The resulting (afocal) magnification can be computed by knowing the locations of the components. However, no independent test is described to confirm it. In addition, if an afocal system is not perfectly aligned, a small amount of beam convergence or divergence may remain in the system. For many applications this slight departure from true afocal performance is not a problem. This slight convergence or divergence of the beam is commonly referred to as xe2x80x9cresidual powerxe2x80x9d, or simply xe2x80x9cpowerxe2x80x9d.
Independent measurement techniques for measuring afocal magnification are known for telescopes and binoculars based on visually comparing the angular subtense of an object, with and without the aid of the binoculars (or a telescope). No special instrumentation is used for this measurement, and accuracy is limited to a few percent with such methods.
More accuracy is attainable by measuring the change in the angle of incoming and outgoing beams, using optical alignment telescopes. Such methods, described hereinafter with reference to FIGS. 1 through 3, may be able to achieve 0.1% accuracy, but are unable to consistently provide the 20 to 50 parts per million accuracy (0.002% to 0.005%) required of certain very high performance afocal systems.
It is therefore an object of the present invention to provide a method for accurately measuring magnification of an afocal optical system.
It is a further object of the present invention to provide a method that allows for simultaneous, closely timed sequential, and/or iterative measurement of wavefront error, power, and magnification of an afocal optical system.
Another object of the present invention to is provide a method that has the ability to adjust or trim either or both the magnification and the power of an afocal system to great accuracy, reducing or eliminating the risk that a system will incur a residual power or wavefront error when adjusting magnification, or vice-versa.
Briefly stated, the foregoing and numerous other features, objects and advantages of the present invention will become readily apparent upon a review of the detailed description, claims and drawings set forth herein. These features, objects and advantages are accomplished by providing a method for measuring magnification of an afocal optical system comprising the steps of directing a collimated light beam through the afocal optical system, intercepting the collimated beam exiting the afocal optical system with an optical beam splitting device such as a prism, generating two return beams at a first angle therebetween with the optical beam splitting device, passing the two return beams through the afocal optical system, observing an interference pattern created by the two return beams after exiting the afocal optical system, measuring a spacing between at least two fringes of the interference pattern, determining an angle between the two return beams exiting the afocal optical system using the spacing of the at least two fringes of the interference pattern, and comparing the angle between the two return beams exiting the afocal optical system to an angle between the two return beams immediately exiting the prism to thereby measure the magnification of the afocal optical system.
The method of the present invention allows for greater accuracy in the measurement of the magnification of an afocal system. The method is especially useful for making or testing multiple afocal units. A specific example is described for a metrology station capable of unit-to-unit magnification control of better than xc2x130 parts/million. | {
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This invention relates in general to the field of prefetch instructions in microprocessors, and more particularly to a microprocessor having a prefetch instruction that prefetches a specified number of cache lines.
Modern microprocessors include a cache memory. The cache memory, or cache, stores a subset of data stored in other memories of the computer system. When the processor executes an instruction that references data, the processor first checks to see if the data is present in the cache. If so, the instruction can be executed immediately since the data is already present in the cache. Otherwise, the instruction must wait to be executed while the data is fetched from the other memory into the cache. The fetching of the data may take a relatively long timexe2x80x94in some cases an order of magnitude or more longer than the time needed for the processor to execute the instruction to process the data.
Many software programs executing on a microprocessor require the program to manipulate a large linear chunk of data. For example, the linear chunk of data might be between 100 to 1,000,000 bytes. Examples of such programs are multimedia-related audio or video programs that process a large chunk of data, such as video data or wave file data. Typically, the large chunk of data is present in an external memory, such as in system memory or a video frame buffer. In order for the processor to manipulate the data, it must be fetched from the external memory into the processor.
If a needed piece of data is not present in the cache, the disparity in data fetching and data processing time may create a situation where the processor is ready to execute another instruction to manipulate the data, but is stalled, i.e., sitting idle waiting for the data to be fetched into the processor. This is an inefficient use of the processor, and may result in reduced multimedia system performance, for example.
In addressing this problem, modern microprocessors have recognized that many times the programmer knows he will need the data ahead of the time for execution of the instructions that actually process the data, such as arithmetic instructions. Consequently, modern microprocessors have added to or included in their instruction sets prefetch instructions to fetch a cache line of the data into a cache of the processor before the data is needed. A cache line is the smallest unit of data than can be transferred between the cache and other memories. An example of a modern microprocessor with a prefetch instruction is the Intel Pentium III(copyright) processor. The Pentium III includes a PREFETCH instruction in its Streaming SIMD Extensions (SSE) to its instruction set.
In many software applications, a programmer knows he will be manipulating a large linear chunk of data, i.e., many cache lines. Consequently, programmers insert prefetch instructions, such as the Pentium III PREFETCH, into their programs to prefetch a cache line. The programmer inserts the prefetch instructions multiple instructions ahead of the actual instructions that will perform the arithmetic or logical operations on the data in the cache line. Hence, a program may have many prefetch instructions sprinkled into it. These added prefetch instructions increase the size of the program code as well as the number of instructions that must be executed.
Furthermore, under the conventional method, not only does the programmer have to sprinkle prefetch instructions into the code, but he also has to try to place them in the code so as to optimize their execution. That is, the programmer has to try to determine the timing of the execution of the prefetch instructions so that the data is in the cache when it is needed. In particular, the programmer attempts to place the prefetch instructions in the code so they do not clobber one another. That is, in conventional processors if a prefetch instruction is currently executing and a subsequent prefetch instruction comes along, one of the prefetch instructions may be treated as a no-op instruction and not executed. This does not accomplish what the programmer wanted, and likely results in lower performance.
One problem a programmer faces when hand-placing prefetch instructions is the variability of core/bus clock ratio. In many modern microprocessors, the clock frequency of the processor bus that connects the processor to the rest of the system is not the same as the clock frequency at which the logic inside the processor operates, which is commonly referred to as the core clock frequency. The core/bus clock ratio is the ratio of the processor core clock frequency to the processor bus clock frequency.
The difference in core clock and processor bus clock frequency is attributed in part to the fact that it is common to sort processors as they are produced according to the core clock frequency that a given integrated circuit will reliably sustain. Hence, it may be that a given processor design will sort into batches of four different core clock frequencies, such as 800 MHz, 900, MHz, 1 GHz, and 1.2 GHz. However, all of these batches of processors must operate in motherboards that are designed to run at one or two fixed bus clock frequencies, such as 100 MHz or 133 MHz. Hence, in the example above, eight different combinations of core/bus clock ratios may occur. Consequently, there may be eight different numbers of core clocks that are required for a typical prefetch to complete.
The fact that a range exists of core clocks required for a typical prefetch to complete makes it very difficult for a programmer to effectively hand-place conventional prefetch instructions. This may be shown by the following example. Assume the highest core/bus clock ratio is 12, and assume a typical prefetch instruction takes about 10 bus clocks or about 120 core clocks. Assume the programmer is programming a loop that processes a single cache line of data, and the loop takes approximately 60 core clocks to execute and is not dependent upon bus activity other than the bus activity generated by the prefetch instruction.
In this case, the programmer may choose to execute a prefetch instruction every other iteration of the loop, i.e., every 120 core clocks, to accommodate the highest core/bus ratio. The programmer""s choice may work well if the ratio is 12. However, if the user has a system in which the ratio is 6, a typical prefetch instruction only takes about 60 core clocks, which is only one iteration through the loop. In this scenario, a prefetch instruction will be active only half the time, which may result in stalls of the processor waiting for the data to be fetched into the cache.
Therefore, what is needed is a microprocessor that supports a prefetch instruction that facilitates efficient prefetching. What is also needed is for the prefetch instruction to efficiently fit into the Pentium III opcode space.
The present invention provides a microprocessor that supports a prefetch instruction that allows a programmer to specify the number of cache lines to prefetch. Accordingly, in attainment of the aforementioned object, it is a feature of the present invention to provide a microprocessor that executes a prefetch instruction specifying a block of cache lines to be prefetched from a system memory into a cache of the microprocessor. The microprocessor includes a prefetch count register that stores a count of the cache lines remaining to be prefetched. The microprocessor also includes a general purpose register, coupled to the prefetch count register, that stores an initial value of the count. The initial value is loaded into the general purpose register by an instruction prior to the prefetch instruction. The microprocessor also includes control logic, coupled to the prefetch count register, that copies the initial value from the general purpose register to the prefetch count register in response to decoding the prefetch instruction.
In another aspect, it is a feature of the present invention to provide a microprocessor. The microprocessor includes an instruction decoder that decodes instructions in an instruction set. The instruction set includes at least a set of instructions defined by an Intel Pentium III processor. The instruction set also includes a repeat prefetch instruction. The repeat prefetch instruction includes a Pentium III PREFETCH instruction opcode, a Pentium III REP string instruction prefix preceding the opcode, and a count specifying a number of cache lines to be prefetched.
In another aspect, it is a feature of the present invention to provide a microprocessor in a system with a system memory. The microprocessor includes an instruction decoder that decodes a prefetch instruction specifying a count of cache lines to prefetch from the system memory and an address in the system memory of the cache lines. The microprocessor also includes an address register, coupled to the instruction decoder that stores the address specified in the prefetch instruction. The microprocessor also includes a count register, coupled to the instruction decoder that stores the count specified in the prefetch instruction. The microprocessor also includes control logic, coupled to the address register, which controls the microprocessor to prefetch the cache lines specified in the address register and the count register from the system memory into a cache memory of the microprocessor.
In another aspect, it is a feature of the present invention to provide a method of a microprocessor prefetching cache lines into its cache. The method includes detecting a repeat prefetch instruction specifying a count of cache lines for prefetching from a system memory address, copying the count from a general purpose register of the microprocessor to a prefetch count register, and storing the address in a prefetch address register. The method also includes prefetching a cache line specified by the prefetch address register into the cache, decrementing the prefetch count register, and incrementing the prefetch address register. The method also includes repeating the prefetching, decrementing, and incrementing steps until the prefetch count register reaches a zero value.
One advantage of the present invention is that it is backward compatible with the existing x86 instruction set architecture. This is because the Pentium III does not generate an exception for a PREFETCH instruction preceded by a REP prefix. Therefore, software programs may be written that include the repeat prefetch instruction of the present invention to execute more efficiently on a microprocessor supporting the repeat prefetch instruction according to the present invention, and the program will also execute correctly on a Pentium III.
Another advantage is that the present invention preserves x86 opcode space by re-using the PREFETCH opcode in combination with the REP prefix to virtually create a new opcode. A further advantage is that the present invention potentially reduces software code size over conventional single-cache line prefetch instructions because fewer prefetch instructions need to be included in the program. A still further advantage is that the present invention potentially improves system performance by making more efficient use of the processor bus than the conventional method. A still further advantage is that the present invention potentially improves processing performance by moving data into the microprocessor cache more efficiently than the conventional method by alleviating the problems caused by the fact that a range of core clock to processor bus clock ratios may exist.
Other features and advantages of the present invention will become apparent upon study of the remaining portions of the specification and drawings. | {
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The present invention relates a communication system having a plurality of network devices connected to a network and obtaining e-mail messages directed to the network devices, respectively, from a mail server which is also connected to the network.
Conventionally, electronic devices each of which is configured to obtain e-mail messages directed thereto from a mail server have been known. An example of such electronic devices is an Internet facsimile device, which obtains an e-mail message attaching an image file from a mail server, and prints out the attached image file. Such a facsimile device is disclosed in Japanese Patent Application Provisional Publication HEI 11-205573.
In such an Internet facsimile device as disclosed in the above-identified publication, a unique e-mail address should be assigned to each device so that an e-mail message is directed to the one destination facsimile device. If a plurality of internet facsimile devices exist on a network (e.g., LAN), different e-mail addresses should be assigned to the plurality of the Internet facsimile devices, respectively. Therefore, when the number of the internet facsimile devices increases, troublesome work for assigning and setting the e-mail addresses should be performed, which results in increasing of the operation cost of such a network system. | {
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The present invention relates to a semiconductor device including metal interconnects and plugs connected to the metal interconnects, and a method for fabricating the same.
The processing dimension of the most advanced semiconductor devices currently mass-produced is 0.18 μm, which will be further reduced in the near future, and the processing dimension of the next generation will be definitely reduced to 0.15 μm, 0.13 μm and 0.1 μm successively. In such trend toward the dimensional reduction, alignment accuracy between a metal interconnect and a plug is preferably ±10% or less.
However, since metal interconnects are thus refined, it is difficult to realize the alignment accuracy of ±10% or less by employing lithography technique alone, and fine processing using a self-alignment method is indispensable.
Also, in currently used multi-layer interconnects, various techniques, such as a technique to use a material having a low dielectric constant k, namely, the so-called low-k material, as an interlayer insulating film and a technique to form an air gap between interconnects, have been developed in order to reduce interconnect delay.
Now, an example of a method for fabricating a semiconductor device including a plug and a metal interconnect by employing the self-alignment method developed for improving the alignment accuracy will be described with reference to FIGS. 17A through 17D, 18A through 18C, 19A through 19C and 20A through 20C.
First, as shown in FIG. 17A, an insulating film 11 of an insulating material is formed on a semiconductor substrate 10 by known chemical vapor deposition (CVD) or spin coating, and thereafter, a plug (not shown) connected to the semiconductor substrate 10 or an interconnect formed on the semiconductor substrate 10 is formed in the insulating film 11. The insulating film 11 is generally made from a silicon oxide film (with a dielectric constant k of approximately 4.3) or a low dielectric film having a dielectric constant lower than that of the silicon oxide film.
Next, as shown in FIG. 17B, a first barrier metal layer 12, a metal film 13 and a second barrier metal layer 14 are successively deposited on the insulating film 11, thereby forming a multi-layer metal film 15. The metal film 13 is made from an aluminum film deposited by known sputtering, and the first and second barrier metal layers 12 and 14 are deposited by the known sputtering and generally made from titanium nitride when the metal film 13 is made from an aluminum film.
Then, as shown in FIG. 17C, a first interlayer insulating film 16 of an insulating material is formed on the multi-layer metal film 15 by the CVD or spin coating, and then, a first resist pattern 17 is formed on the first interlayer insulating film 16 by known lithography.
Thereafter, as shown in FIG. 17D, the first interlayer insulating film 16 is dry etched by using the first resist pattern 17 as a mask, thereby forming via holes (via holes) 18 in the first interlayer insulating film 16.
Next, as shown in FIG. 18A, a conducting film 19 is deposited on the first interlayer insulating film 16 by the CVD so as to fill the via holes 18. The conducting film 19 is made from, for example, a tungsten film, and although not shown in the drawing, a barrier metal layer of a titanium film or a titanium nitride film is formed by the sputtering under the conducting film 19.
When the via hole 18 has an aspect ratio (a ratio of the depth to the diameter) higher than approximately 4, a void 20 is formed in the conducting film 19 within the via hole 18.
Then, a portion of the conducting film 19 present on the first interlayer insulating film 16 is removed by, for example, chemical mechanical polishing (CMP), so as to form plugs 21 as shown in FIG. 18B. Thereafter, the first interlayer insulating film 16 is dry etched so as to reduce the thickness of the first interlayer insulating film 16 as shown in FIG. 18C.
Subsequently, as shown in FIG. 19A, a second resist pattern 22 is formed on the first interlayer insulating film 16 with the reduced thickness, and then, the first interlayer insulating film 16 is dry etched by using the second resist pattern 22 as a mask, thereby forming a patterned first interlayer insulating film 16A as shown in FIG. 19B.
Next, the multi-layer metal film 15 is dry etched by using the plugs 21 and the patterned first interlayer insulating film 16A as a mask, thereby forming the multi-layer metal film 15 into metal interconnects 15A as shown in FIG. 19C. Since the plugs 21 and the metal interconnects 15A have a self-alignment structure in this manner, the positional shift between the plugs 21 and the metal interconnects 15A can be avoided.
The second resist pattern 22 is removed by ashing before or after the dry etching of the multi-layer metal film 15. Even when the second resist pattern 22 is removed after the dry etching of the multi-layer metal film 15, a portion of the second resist pattern 22 present on the plugs 21 is eliminated during the dry etching of the multi-layer metal film 15. Therefore, upper portions of the plugs 21 are slightly etched, and hence, openings 20a are formed in the upper portions of the voids 20.
Next, the insulating film 11 and the patterned first interlayer insulating film 16A are dry etched, thereby reducing the thicknesses of the insulating film 11 and the patterned first interlayer insulating film 16A as shown in FIG. 20A.
Then, as shown in FIG. 20B, a second interlayer insulating film 23 is deposited over the semiconductor substrate 10 by the CVD, thereby forming air gaps 24 between the metal interconnects 15A. Thereafter, the second interlayer insulating film 23 is planarized by the CMP as shown in FIG. 20C.
When the procedures of FIG. 17A through FIG. 20C are repeatedly carried out subsequently, a semiconductor device having a multi-layer interconnect structure including air gaps can be fabricated.
In the conventional method for fabricating a semiconductor device, however, when the via hole 18 has an aspect ratio higher than approximately 4, the voids 20 are formed within the plugs 21 as shown in FIG. 18B. Therefore, when the metal interconnects 15A having the air gaps 24 are formed, the complete openings 20a of the voids 20 are formed in the plugs 21 as shown in FIG. 20C.
Accordingly, the electric resistance between the plug 21 and an upper metal interconnect formed on the second interlayer insulating film 23 is largely increased, which causes a problem that the device characteristic is degraded.
In this case, when the electric resistance between the contact plug 21 and the upper metal interconnect is large beyond the limit, the reliability of the metal interconnect structure is largely lowered, and the semiconductor device cannot be operated in the worst case.
Furthermore, in the planarization of the second interlayer insulating film 23 by the CMP, an abrasive used in the CMP enters the voids 20, which causes a problem that the plugs 21 are corroded by the abrasive. | {
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As described in Patent Literature 1, an absorbent body with a desired shape is formed in such a way that, a pulp sheet is crushed by a crusher including a plurality of rotating blades into fluff pulp, a mixed flow is formed by carrying the fluff pulp on an air flow to a duct and at the same time supplying a water absorbing polymer in the duct to be merged with the fluff pulp carrying flow, and the mixed flow is then transported to a rotating fiber stacking drum so that the mixed flow is adsorbed and retained by an adsorbent molding section which is formed on the outer circumference of the rotating fiber stacking drum. | {
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1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a semiconductor device or a display device using a polycrystalline semiconductor layer obtained by laser annealing a non-single crystal semiconductor layer on a substrate.
2. Description of the Prior Art
A flat display device comprising a display element using a liquid crystal and organic electroluminescence as optical members is small-sized, thin and has low power consumption, and has been developed for practical use in the field of OA apparatus, AV apparatus and the like. A liquid crystal display (LCD) and an organic EL display of an active matrix type having a thin film transistor (TFT) formed on a substrate supporting a liquid crystal and EL as a switching element for controlling the timing of holding and writing image data in each pixel has become commonplace because of high display quality. In particular, a display of a driver built-in type has been developed in which a TFT is used as a switching element of each pixel and is also used for a driver to drive the switching element, and the driver is formed together with the switching element on the periphery of a display area where each pixel is arranged. Consequently, size and cost can be reduced still further.
For the display of a driver built-in type, a TFT using a polycrystalline semiconductor film, particularly, polysilicon (p-Si) as a channel layer is suitable because it can achieve an operating speed which is also applicable to a driver and has a low deposition temperature resulting in formation on an inexpensive glass substrate having low heat resistance. When the polysilicon is to be formed, amorphous silicon formed on the substrate is laser annealed so that crystallization can be performed with a support substrate temperature set to 400 to 600xc2x0 C. The TFT is formed using p-Si thus obtained. Using this method, a driver circuit can be fabricated on a non-alkaline glass substrate.
The amorphous silicon (a-Si) is laser annealed by using a laser irradiation apparatus. In the laser irradiation apparatus, an optical system shapes a pulse laser beam emitted from a laser oscillation source into a beam having a predetermined section, and the beam thus obtained is irradiated on an amorphous silicon film formed on a processed substrate. The laser beam to be shaped and irradiated on the silicon film is, for example, square, and more particularly has the form of a belt or line in which a length in a direction of a major axis is much greater than that in a direction of a minor axis. A stage of the laser irradiation apparatus to be mounted on the processed substrate having an a-Si film formed thereon is movable horizontally and vertically in a plane direction. The stage is moved horizontally or vertically so that a pulse laser beam is relatively scanned over the a-Si film formed on the processed substrate horizontally or vertically.
FIG. 1 shows an enlarged sectional structure of a TFT portion formed on the processed substrate at a laser. annealing step A gate electrode 11 of a TFT is formed on a substrate 10 such as a non- alkaline glass. A gate insulation film 12 is formed to cover the gate electrode 11 and an a-Si film 13a which is a film to be laser annealed is formed on the gate insulation film 12. When a pulse laser beam is irradiated on the a-Si film 13a to perform the laser annealing, the a-Si film 13a is polycrystallized to form a p-Si film 13.
FIG. 2 shows a sectional structure of the TFT formed by using the p-Si film 13 obtained by laser annealing. FIG. 3 shows a planar structure of the obtained TFT. FIGS. 1 and 2 show sections taken along the line Axe2x80x94A in FIG. 3.
The p-Si film 13 obtained by laser annealing the a-Si film 13a is subjected to patterning in the shape of an island across a portion above the gate electrode 11. A region positioned just above the gate electrode 11 in the island-shaped p-Si film 13 is a non-doped channel region CH. A LD (Lightly Doped) region LD which is doped with an impurity having a low concentration is formed on both sides of the non-doped channel region CH, and a source region S and a drain region D which are doped with an impurity having a high concentration are formed on the outside of the LD region LD. An interlayer insulation film 15 such as SiNx, SiO2 or the like is formed to cover an implantation stopper film 14 used as a mask when the p-Si film 13 and the LD region LD are to be formed. A source electrode 16 and a drain electrode 17 are formed on the interlayer insulation film 15, and are connected to the source region S and the drain region D through a contact hole CT formed in the interlayer insulation film 15, respectively.
In a display unit, for example an LCD, pixels re usually arranged in a matrix and TFTs for driving the pixels and wirings are correspondingly placed in horizontal and vertical scanning directions, respectively. Accordingly, when these display elements are usually placed on a rectangular substrate, the directions of a plurality of TFTs formed on the processed substrate, that is, extension directions of channel widths or channel lengths of the channel regions CH, are any of a horizontal scanning direction H and a vertical scanning direction V of the LCD with respect to a substrate plane. In other words, the directions of the channels of the TFT elements are parallel or perpendicular to each other. A direction of a line beam, that is, a side of the line beam, a side of the substrate and the like are held in the horizontal scanning direction H or the vertical scanning direction V.
FIG. 4 is a graph showing a relationship between an irradiation laser energy on the a-Si film 13a (an axis of abscissa) and a grain size of the p-Si film 13 formed at that time (an axis of ordinate). As the energy is increased, the grain size is also enlarged. If an energy value Eo with which a maximum grain size is obtained is exceeded, the grain size is rapidly reduced. Accordingly, the energy should be kept within a narrow range between Ed and Eu in order to obtain a predetermined grain size.
For this reason, if the irradiation energy of the line beam is slightly varied and moves out of the optimum range between Ed and Eu, crystallization cannot be performed fully so that a defective crystallization region R having a small grain size is generated on a certain region in the p-Si film 13.
A positional relationship between a layout of each circuit element for liquid crystal driving which is formed on a processed substrate, for example, and an irradiated pulse laser beam is usually set as shown in FIG. 5. In FIG. 5, a mother substrate 59 acting as the processed substrate has a plurality of regions forming an active matrix substrate used for a TFT LCD (six regions, each of which will be hereinafter referred to as an active matrix substrate 2). Each active matrix substrate 2 is subjected to various manufacturing steps so that pixels are formed in a matrix and a p-Si TFT to be connected to each pixel is formed in a region 43 of FIG. 5, resulting in a display area (hereinafter referred to as a display area 43). Driver sections 44 and 45 are formed around the display area 43. The driver sections 44 and 45 serve to drive the p-Si TFT of the display area 43 and utilize a p-Si TFT formed almost simultaneously with the formation of the p-Si TFT of the display area 43.
FIG. 5 shows a state in which an amorphous silicon (a-Si) film is formed in a necessary region of the mother substrate 59 and a line-shaped laser beam that causes an irradiated region LB to extend in the vertical scanning direction V is sequentially shifted and irradiated on the a-Si film in the horizontal scanning direction H to perform annealing. By such laser annealing, a-Si is polycrystallized so that a p-Si film constructing a channel region of the TFT is obtained.
Thus, the annealing is performed by irradiating the pulse laser beam while sequentially shifting a position of the pulse laser beam. Therefore, a direction of an edge of the region where the laser beam is irradiated is usually coincident with the direction of the sides of the processed substrate as shown in FIG. 5 It has been confirmed that the defective crystallization region R is easily generated in the direction of the edge of the region LB where the laser beam is irradiated. In particular, a direction of a major axis of the region LB orthogonal to the scanning direction of the beam which is coincident with the horizontal scanning direction H of the substrate is shown in FIG. 5.
For this reason, a relationship between the channel region of the TFT formed on the processed substrate and the defective crystallization region R is often set as shown in FIG. 3 For example, a TFT used for the drivers 44 and 45 or the like takes a slender shape having a channel width W of the channel region CH greater than a channel length L as shown in FIG. 3 in order to particularly enhance operating speed and driving capability. A TFT used for a TFT LCD or the like often has the direction of a channel width and that of a channel length which are coincident with the directions of the sides of the substrate as described above. With such a layout, the direction of a channel, that is, an extension of the channel width W and an extension of a major axis of the defective crystallization region R are parallel or perpendicular to each other as shown in FIG. 3.
FIG. 3, in the case where a defective crystallization region RL divides the channel region CH vertically, that is, a defective crystallization region RL is generated in the direction of the length of the TFT channel A part MN of a moving path in the channel region CH is occupied by the defective crystallization region RL to cause deterioration and a residual moving path MG does not overlap the defective crystallization region RL in the direction of the channel width Accordingly, a width of the moving path decreases so that a substantial channel width is reduced. However, electrical characteristics are not greatly affected but elements can perform normal operation.
On the other hand, in a case where the defective crystallization region RW divides the channel region CH transversely, that is, the defective crystallization region RW generated in the direction of the channel width is formed to have a length greater than the channel width, a moving path MNh of the TFT is blocked over the whole channel width by the defective crystallization region Rw even if the defective crystallization region RW is a part of the channel region CH. Therefore, the characteristics of the TFT are noticeably deteriorated.
The present invention provides a semiconductor device having a plurality of semiconductor elements formed on a substrate, some or all of the semiconductor devices having a channel region formed in a semiconductor film annealed by irradiation of a pulse laser beam, a channel width of the channel region being greater than a mutual pitch of the pulse laser beam irradiated by shifting a position, and the channel region being formed in such a manner that the direction of the channel width is not coincident with the directions of the major and minor axes of a region where the pulse laser beam is irradiated.
Furthermore, the present invention is characterized in that the directions of the sides of the substrate are almost the same as the directions of the major and minor axes of the region where the pulse laser beam is irradiated, and the direction of the channel width of the channel region is different from the directions of the sides of the substrate.
Alternatively, it is also possible to employ a structure in which the directions of the sides of the substrate are almost the same as the direction of the channel width of the channel region, and the directions of the major and minor axes of the region where the pulse laser beam is irradiated are different from the directions of the sides of the substrate.
With such a structure, even if a defective laser-annealed region formed in the semiconductor film with the same width as the pitch of the pulse laser beam is generated in the vicinity of the channel region of the semiconductor element, the channel region can be prevented from being occupied by the defective processed region over the whole channel width. Consequently, characteristics of the semiconductor element can be prevented from being deteriorated.
In the present invention, it is also possible to use a structure in which some semiconductor elements have a polycrystalline semiconductor film formed on the substrate by polycrystallizing an amorphous semiconductor by annealing using irradiation of a pulse laser beam, a channel region formed in an island region of the polycrystalline semiconductor film, and a gate electrode formed to overlap the channel region with an insulation film provided therebetween.
In another aspect of the present invention, a channel width W of the channel region, a pitch P of the pulse laser beam, and an angle xcex8 formed by the direction of the channel width of the channel region and the direction of the major axis of the region where the pulse laser beam is irradiated have a relationship satisfying Wxc2x7sin xcex8 greater than P.
Furthermore, it is also possible to apply a structure if a channel length of the channel region is set to L, a pitch P of the pulse laser beam and the angle xcex8 formed by the direction of the channel width of the channel region and the direction of the major axis of the region where the pulse laser beam is irradiated have a relationship satisfying Wxc2x7sin xcex8xe2x88x92L cosxc2x7xcex8 greater than P.
With such a structure where the defective treated region obtained by the annealing is formed in the vicinity of the channel region of the semiconductor element, the channel region can be reliably prevented from being occupied by the defective treated region over the entire channel width.
In yet another aspect of the present invention, if a channel width W of the channel region, a channel length L of the channel region, a pitch P of the pulse laser beam, and an angle xcex8 formed by the direction of the channel width of the channel region and the direction of the major axis of the region where the pulse laser beam is irradiated have a relationship satisfying Wxc2x7sin xcex8xe2x88x92Lxc2x7cos xcex8 greater than P, the channel region can be more reliably prevented from being occupied by a defective annealed region.
A further aspect of the present invention is directed to a semiconductor device having a plurality of semiconductor elements formed on a substrate, some or all of the semiconductor elements formed on a substrate, some or all of the semiconductor devices having a polycrystalline semiconductor film formed on the substrate by polycrystallizing an amorphous semiconductor by annealing using irradiation of a pulse laser beam, a channel region formed in an island region of the polycrystalline semiconductor film, and a gate electrode formed to overlap the channel region with an insulation film provided therebetween, the semiconductor device having a lightly doped drain structure, a channel width of the channel region being greater than a mutual pitch of the pulse laser beam irradiated by shifting a position, and the channel region being formed in such a manner that a direction of the channel width is not coincident with the directions of the major and the minor axes of a region where the pulse laser beam is irradiated.
Also in such a semiconductor element having a LDD structure, the channel region of the semiconductor device is formed to have the above-mentioned relationship with the pitch of the pulse laser beam. Consequently, the characteristics of the semiconductor device can be prevented from being deteriorated.
Furthermore, the present invention is characterized in that a channel width W of the channel region, a channel length L of the channel region, a length L1 of the lightly doped region, a pitch P of the pulse laser beam, and an angle xcex8 formed by the direction of the channel width of the channel region and the direction of the major axis of the region where the pulse laser beam is irradiated can have a relationship to satisfy Wxc2x7sin xcex8xe2x88x92(L+L1)xc2x7cos xcex8 greater than P.
By employing such a structure of the semiconductor device, where the defective treated region obtained by the annealing is formed in the vicinity of the channel region of the semiconductor element having the LDD structure, the channel region and the LD region which greatly affected element characteristics can be reliably prevented from being occupied by the defective treated region in the direction of the channel width.
A further aspect of the present invention is directed to a display device having the same characteristics as in the above-mentioned semiconductor device. The display device comprises, on a substrate, a plurality of first thin film transistors for supplying a display signal to corresponding pixels, respectively, and a plurality of second thin film transistors constructing a driver circuit for driving the first thin film transistors, the first and/or second thin film transistors having channel regions provided in polycrystalline semiconductor films formed on the substrate by polycrystallizing an amorphous semiconductor by annealing using irradiation of a pulse laser beam, some or all of the second thin film transistors having a channel width of the channel region which is greater than a mutual pitch of the pulse laser beam irradiated by shifting a position, and the channel region being formed in such a manner that the direction of the channel width is not coincident with directions of the major and minor axes of a region where the pulse laser beam is irradiated.
If characteristics of the second thin film transistors for driving the first thin film transistors corresponding to the pixels are deteriorated, the quality of the display is significantly affected than in a deterioration in characteristics of the first thin film transistors. Accordingly, the channel regions of the second thin film transistors are formed as described above so that they can be prevented from being occupied over the entire channel widths by the defective treated region obtained by the laser annealing. Thus, the characteristics of the second thin film transistors can be prevented from being deteriorated.
The display device according to the present invention can have a structure in which a channel width W of the channel region, a pitch P of the pulse laser beam, and an angle xcex8 formed by the direction of the channel width of the channel region and the direction of the major axis of the region where the pulse laser beam is irradiated have a relationship satisfying Wxc2x7sin xcex8xe2x88x92P. With such a structure, the characteristics of the second thin film transistors can be reliably prevented from being deteriorated.
A further aspect of the present invention is directed to a semiconductor device having a plurality of semiconductor elements formed on a substrate, some or all of the semiconductor elements having a channel region formed on a semiconductor film annealed by irradiation of a pulse laser beam, the channel region being formed by a plurality of channel region parts which are separated from each other and are electrically connected in parallel, and a sum of each of the channel widths of the channel region parts and a space between the channel region parts being greater than a mutual pitch of the pulse laser beam irradiated by shifting a position.
A further aspect of the present invention is directed to the semiconductor apparatus wherein the channel region parts are respectively separated in the directions of the channel widths.
Also in a case where the channel region of the semiconductor device is thus formed for the pitch of the pulse laser beam, the whole channel width of the channel region of the semiconductor device can be prevented from being occupied by the defective treated region obtained by the laser annealing. Thus, the characteristics of the semiconductor device can be prevented from being deteriorated.
A further aspect of the present invention is directed to a display device comprising, on a substrate, a plurality of first thin film transistors for supplying a display signal to corresponding pixels, respectively, and a plurality of second thin film transistors constructing a driver circuit for driving the first thin film transistors, the first and/or second thin film transistors having channel regions provided in polycrystalline semiconductor films formed on the substrate by polycrystallizing an amorphous semiconductor by annealing using irradiation of a pulse laser beam, some or all of the second thin film transistors having a channel region formed by a plurality of channel region parts which are separated from each other and are electrically connected in parallel, and a sum of each of the channel widths of the channel region parts and a space between the channel region parts being greater than a mutual pitch of the pulse laser beam irradiated by shifting a position.
If characteristics of the second thin film transistors for driving the first thin film transistors corresponding to the pixels as described above are deteriorated, the quality of display is more significantly affected than in a deterioration in characteristics of the first thin film transistors. The channel regions of the second thin film transistors are formed to have the above-mentioned relationship with the pitch of the pulse laser beam so that they can be prevented from being occupied over the whole channel widths by the defective treated region obtained by the laser annealing. Thus, the characteristics of the second thin film transistors can be prevented from being deteriorated. | {
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The present invention relates to managing clock skew when separate clock meshes are employed to provide different clock frequencies to different portions of a large scale integrated (LSI) circuit.
A system clock signal is often used by digital circuitry, such as digital circuitry implemented using a LSI circuit, to synchronously execute certain logic functions. For example, ultra-deep sub-micron (UDSM) microprocessors employ digital circuitry that use system clock signals to synchronously execute logic functions. These microprocessors operate at system clock frequencies of 1 GHz and higher. The system clock signal of a given LSI circuit is often split into many paths to service many different portions of the digital circuitry. Ideally, the system clock signals at different portions of the digital circuitry exhibit exactly the same timing characteristics so that the different portions of the digital circuitry operate in exact synchronization. In practice, however, the system clock signals at various points throughout the digital circuitry exhibit differing timing characteristics, such as differing rising and/or falling edges (i.e., transitions), differing duty cycles, and/or differing frequencies. These non-ideal characteristics are often referred to as clock jitter and clock skew.
Clock jitter relates to the inaccuracies inherent in generating the system clock signal. The non-ideal characteristics of the system clock signals due to clock jitter affect all portions of the LSI circuit in the same way, irrespective of how the system clock signals are distributed to those portions of the circuit. Clock skew relates to the inaccuracies introduced into the system clock signals by the distribution technique employed to split the system clock into many paths and deliver the clock signals to different portions of the digital circuit.
Sources of clock skew may be classified as being statically occurring or dynamically occurring. Statically occurring sources of clock skew are caused by the LSI design or manufacturing process irrespective of the operating conditions of the LSI circuit. Dynamically occurring sources of clock skew are caused by the operating conditions of the LSI circuit, which may also be functions of the LSI circuit design or manufacturing process.
Statically occurring sources of clock skew include (i) variations in transistor load capacitance (e.g., gate load capacitance); (ii) RC delay of circuit interconnections (e.g., the asymmetry of wire lengths and widths); (iii) variations and/or asymmetries in cross-coupling capacitance between wires (e.g., inter-wiring capacitance); and (iv) semiconductor process variations (e.g., transistor threshold voltage variations, transistor ON resistance variations, wiring variations, vias, and contact RC variations).
Dynamically occurring sources of clock skew include (i) cross-coupling between wire lengths due to inter-wiring capacitance; (ii) cross-coupling between wire lengths due to inductive coupling; (iii) cross-coupling due to return path current; (iv) temperature variations; and (v) variations in VDD and VSS (e.g., DC operating voltage variations).
Unfortunately, the variations in the timing characteristics of the system clock signals due to clock skew result in undesirable errors in the operation of the digital circuitry of the LSI circuit. The problem is exacerbated as the size (i.e., number of logic gates and corresponding circuit area) increase and/or as the clock signal frequency increases.
Various techniques have been developed and employed to ameliorate the undesirable affects of clock skew. These techniques include (i) utilizing clock bars (i.e., relatively wide bars to carry the system clock to various portions of the LSI circuit); (ii) RC delay balancing (i.e., wiring techniques that focus on wiring geometry to match RC delay characteristics); (iii) utilizing a grid structure in distributing the system clock signal; (iv) utilizing a hierarchical structure in partitioning the LSI circuit into regions; (v) utilizing active feedback in compensating the system clock signal; (vi) utilizing local oscillators in various regions of the LSI circuit and an overall resonance for the LSI circuit; and (vii) utilizing the resonances of wiring loops. For various reasons, these techniques have not been adequately successful in addressing the undesirable problems caused by clock skew.
FIG. 1 is a schematic diagram of a circuit 100 in which a single clock signal is distributed to a clock mesh 106 via a clock tree 104 employing a conventional approach. After the signal emerges from the PLL (Phase-Locked Loop), OSC (Oscillator) or other clock source 102, the signal branches off along several possible paths within clock tree 104 before reaching clock mesh 106. A plurality of clock buffers 108 are used to fan the clock signal out to multiple points on the clock mesh 106. Various points in circuit 100 will experience clock skew for all the reasons discussed above.
FIG. 2 is a schematic diagram of a circuit 200 in which two separate clock signals, at different frequencies, are distributed to respective meshes 206 and 216 along separate respective clock trees 204 and 214. The clock skew problem is exacerbated when separate clock trees and separate clock meshes are employed to deliver different clock frequencies to different portions of a circuit.
FIG. 2 illustrates a conventional approach for implementing a 4-GHz (gigahertz) clock mesh 206 and a 2 GHz clock mesh 216. Circuit 200 accomplishes this by providing a ½ frequency divider 212 coupled to the output of 4 GHz oscillator 202 and by providing separate clock trees 204, 214 to deliver the 4 GHz and 2 GHz clock signals, respectively, to the 4 GHz clock mesh 206 and the 2 GHz clock mesh 216, respectively. Employing this configuration, the point of synchronization between the two signals is located where the 4 GHz signal is directed to the frequency divider 212 to generate the 2 GHz signal. From that point onward, as the signals propagate along their respective clock trees toward their respective clock meshes, clock skew will generally become progressively worse as each length of wire and each device through which each signal travels introduces another opportunity for disparities in the speed of propagation of the respective signals to arise.
FIG. 3 is a timing diagram illustrating clock skew occurring within the circuit of FIG. 2. Graph 302 is a plot of the 4 GHz signal at the output of the oscillator 202. Graph 304 is a plot of the 2 GHz signal generated from the 4 GHz signal at the output of the ½ frequency divider 212, under ideal conditions. Graphs 306 and 308 illustrate 2 GHz clock signals that may appear at different points in the clock mesh 216. Clock skew for the 2-GHz signals, illustrated by graphs 306 and 308, with respect to the 4 GHz signal illustrated by graph 302 is apparent.
Conventional techniques for reducing the resulting clock skew between separate meshes are very complex. Accordingly, there is a need in the art for a simpler solution to the problem of clock skew between clock meshes operating at different frequencies. | {
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1. Field of the Invention
This invention relates to a locking device for doors, windows or the like, which is applicable more particularly to fittings for doors, windows or the like.
2. The Prior Art
As a rule, a house door is locked by means of a casement lock either mortised in the edge of the jamb of the movable frame of the door, or fastened to the main surface thereof. This casement lock comprises a mechanism transmitting the movement impressed to the handle to locking means such as a half-turn bolt or a plurality of bolting members somewhat spaced from each other and connected to the mechanism by means of control rods. These casement locks comprise in general a cylinder lock actuated by means of a key and driving a fixed bolt. The various locking means comprising the bolts, the half-turn bolt and the dead bolt are actuated by a particularly complicated mechanism which increases considerably the cost of the casement lock.
On the other hand, casement locks are also known which comprise a half-turn bolt and/or a plurality of bolts or locking members somewhat spaced from the casement bolt case and actuated by control rods. All the bolt members are retracted only by means of a handle, not by means of a handle plus the key of a cylinder lock, as in the case of a casement lock.
In frequent cases the above-mentioned casement locks or casement bolts are used for closing and locking doors and may also be used for closing windows.
However, the two types of locks mentioned hereinabove are attended by various inconveniences.
Casement locks, as already mentioned, are relatively complicated and therefore expensive. The complexity of their component elements is also likely to reduce the useful life of the locking means.
On the other hand, in the case of casement bolts, it is possible to open the door, window closure or the like from outside by actuating the bolts thereof. These bolts are rigidly connected to rods and can easily be released from the keepers or striker plate fastened or formed on the fixed jamb of the frame by simply hooking the bolts and pulling them down to their release position. If the casement bolt comprises only a single half-turn bolt, a simple tool of any kind is sufficient for retracting and recessing the half-turn bolt, in case the latter is adapted to rotate about an axis, and it is also possible to retract the half-turn bolt by rotating it through a half-turn in the opposite direction.
A backward movement of the locking member is attained almost automatically by the rotation of the control handle. It is therefore advisable to lock this handle against rotation and thus present any actuation of the locking members.
For this purpose, a handle has already been proposed which incorporates a locking device. As a rule, this handle is relatively bulky in cross section since all the component elements of the locking device must be enclosed therein. For the sake of convenience, this handle has the appearance of a round-sectioned knob. However, this arrangement for locking a door or window is applicable only to a well-defined handle construction and therefore restricts the choice of a handle from the dual point of view of shape and type. On the other hand, the relatively large cross-sectional area of the handle may also prove detrimental, notably in case the frame of the door or window has a relatively narrow jamb.
It is the essential object of the present invention to avoid the above-described inconveniences. | {
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Switch mode power supplies can efficiently convert electrical power from a source to a load, or to several different loads, with each corresponding to a different output. The main transistor of a switching-mode supply can switch between on and off states at a given operating frequency, and voltage regulation can be achieved by varying the ratio of the on-to-off time of the main transistor. Switch mode power supplies may have relatively high power conversion efficiency, as compared to other types of power converters. Switch mode power supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight. | {
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In general, a motor is provided in a compressor which is a mechanical apparatus for receiving power from a power generation apparatus, such as an electric motor, a turbine, etc. and compressing the air, refrigerant or other various operating gases to raise a pressure. The motor has been widely used in electric home appliances such as refrigerators, air conditioners, etc., and its application has been expanded to the whole industry.
Specifically, the compressors are roughly classified into a reciprocating compressor in which a compression space for sucking and discharging an operating gas is defined between a piston and a cylinder so that the piston can be linearly reciprocated in the cylinder to compress a refrigerant, a rotary compressor in which a compression space for sucking and discharging an operating gas is defined between an eccentrically-rotated roller and a cylinder so that the roller can be eccentrically rotated along the inner wall of the cylinder to compress a refrigerant, and a scroll compressor in which a compression space for sucking and discharging an operating gas is defined between an orbiting scroll and a fixed scroll so that the orbiting scroll can be rotated along the fixed scroll to compress a refrigerant.
Recently, a linear compressor which not only improves a compression efficiency but also has a simple structure has been actively developed among the reciprocating compressors. In particular, the linear compressor does not have a mechanical loss caused by a motion conversion since a piston is directly connected to a linearly-reciprocating driving motor.
FIG. 1 is a block diagram of a motor control device used in a conventional linear compressor.
As illustrated in FIG. 1, the motor control device includes a rectification unit having a diode bridge 11 receiving, rectifying and outputting AC power which is commercial power and a capacitor C1 smoothing the rectified voltage, an inverter unit 12 receiving a DC voltage, converting the DC voltage to an AC voltage according to a control signal from a control unit 17, and supplying the AC voltage to a motor unit, the motor unit having a motor 13 and a capacitor C2 connected in series to the motor 13, a voltage sensing unit 14 sensing a both-end voltage of the capacitor C1, a current sensing unit 15 sensing a current flowing through the motor unit, an operation unit 16 operating a counter electromotive force (EMF) from the voltage sensed by the voltage sensing unit 14 and the current sensed by the current sensing unit 15, and the control unit 17 generating a control signal by reflecting the counter EMF from the operation unit 16 and the current sensed by the current sensing unit 15.
In the conventional linear compressor shown in FIG. 1, additional costs and space are needed because the capacitor C2 connected in series to the motor 13 is provided in the linear compressor. In addition, although the cooling capacity modulation characteristics based on the load are determined by the capacity of the capacitor C2, in the prior art, it is not easy to change the capacity of the capacitor C2. Moreover, the preparation and selective connection of a plurality of capacitors cause difficulties in terms of cost, space, and design.
FIG. 2 is a graph showing changes of a stroke and an input voltage of the motor of FIG. 1. In the conventional linear compressor, if the capacitor C2 is removed in a simple manner, as shown in FIG. 2, a phenomenon in which a voltage applied to the motor is reduced, i.e., a jump phenomenon occurs near the top dead center (TDC), so that the cooling capacity modulation (under stroke operation) is impossible. In the graph of FIG. 2, the closer to 0.00, the closer to the TDC. | {
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There are many different configurations of hybrid and/or all electric vehicles. Some embodiments of hybrid vehicles provide drive torque to the wheels of both a front axle and the wheels of a rear axle. Accordingly, the wheels of the front axle are provided with drive torque to propel the vehicle, as well as the wheels of the rear axle being provided with drive torque to propel the vehicle. The wheels of the front axle and the wheels of the rear axle may be provided with their respective drive torque by one or more power sources, which may include but are not limited to an internal combustion engine and/or an electric motor. For example, a front axle may be powered by an electric device, and the rear axle may be powered by an internal combustion engine. Alternatively, all the wheels of the front axle, and all the wheels of the rear axle may each be powered by independent electric devices.
The front axle and the rear axle may be either coupled, or de-coupled. If the front axle and the rear axle are coupled, then the first axle and the second axle are mechanically linked together, and are capable of directly transferring torque therebetween. If the front axle and the rear axle are de-coupled, then the front axle and the rear axle are not mechanically linked together, may be considered separated mechanical systems, and are not capable of directly transferring torque therebetween.
Hybrid vehicles may convert kinetic energy from the rotating wheels into some other form of energy. For example, hybrid vehicles using an electric device to provide a propulsive force to an axle typically include an energy storage device, e.g., a battery or other similar device. The energy storage device must be charged, referred to herein as regeneration. Regeneration of the energy storage device may be accomplished in several different ways. For example, the energy storage device may be regenerated through a regenerative braking process, in which energy used to decelerate the vehicle is converted into electrical energy that is stored in the energy storage device. The regenerative braking process may be implemented at one or both of the front axle and/or the rear axle. Alternatively, the electric device (or a second electric device) may be operated as a generator to charge the energy storage device. The control strategy used to control the internal combustion engine and/or the electric device determines how the energy storage device is regenerated for specific, different vehicle dynamic operating conditions, such as forward acceleration or deceleration, lateral acceleration, engine torque, etc. Alternatively, the kinetic energy from the wheels may be converted into a form of energy other than electrical energy. For example, the energy storage device may include a weighted flywheel, in which case the kinetic energy from the wheels is transferred to kinetic energy of the flywheel. | {
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1. Field of the Invention
This invention relates to the field of processors for data-processing systems, and in particular to a method for increasing the robustness of an interrupt handling mechanism.
2. Description of the Related Art
In a data-processing system the basic logical arithmetic computational operations are performed by the processor. The processors use a processor core operating under control of program instruction words, which when decoded serve to generate control signals to control the different elements within the processor core to perform the necessary functions to achieve the processing specified in the program instruction word. For this purpose there is provided within the processor core a number of registers and logic circuits. The processor registers are used to receive, hold, and transmit information (data and instructions) used by the processor. Several different types of registers are provided within the typical processor core. For example, an accumulator register temporarily stores data and accumulates the results of logical or arithmetic operations. A program counter stores the address of the next instruction in memory to be executed. An instruction register stores the instruction code (also known as the operation code) portion of instruction which is currently being executed by the processor, and an address register or data counter stores the operand portion of the currently executing instruction.
The processor executes the instructions of a program in a sequence known as a program control flow. As the processor moves through the program control flow, it performs the functionality specified by the program. The processor is designed to move through the program control flow in a manner specified by the program, except when an exception occurs. Exceptions cause the processor to (a) mark the current point in the program control flow, and (b) start executing an exception routine. Possible triggers of an exception include illegal conditions in the processor and processor interrupts. If one of these triggers occurs, it is desired that the processor attempt to resolve the exception, and the manner for resolving the exception is specified by the exception routine. The exception routine often begins by determining the source of the exception then taking appropriate action. Typically this involves storing the contents of the registers and invoking a handling routine which is designed to handle the source of the exception. For interrupts, the handling routines typically treat the interrupt as a request for a desired service, perform the service, and then cause the processor to return to the marked point in the program control flow. For illegal conditions, the handling routines may halt the program or search for a specified corrective action to take.
At any given instant in complex or pipelined processors, multiple modules of the processor can be actively involved in the executing of the program control flow, and each must be notified when an exception trigger occurs before the transfer of control to the exception routine can be fully accomplished. The notification mechanism to these modules can be different, and a spurious assertion of an exception trigger (i.e. an interrupt) may cause some modules to be notified while others are not. If any of these modules is not notified, the processor enters an undefined state. It is desirable to prevent this from happening without redesigning the carefully optimized asynchronous interaction between the various modules. | {
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1. Field of the Invention
The present invention relates to an electronic device and method for connecting a die to a connection terminal. In particular, the invention regards a ribbon-bonding method.
2. Discussion of the Related Art
As is known, in the technical field of packaging of integrated electronic circuits, there is felt the need to connect electrically dies and connection terminals (also known as posts) by means of bonds that introduce low values of resistance, and withstand, without melting, the passage of high currents, in the region of 150-200 A. This need is particularly felt in the case of so-called power packages, which are commonly used for packaging integrated circuits that form devices with high current consumption, such as, for example, power diodes, low-voltage power MOSFETs, or insulated-gate bipolar transistors (IGBTs).
As is known, in order to bond a die to a connection terminal, commonly used today are the so-called wire-bonding, clip-bonding, and ribbon-bonding techniques.
By way of example, FIG. 1 is a schematic illustration of a package 1, which is formed by a die-pad area 2 of metal material and having the function of carrying a die 4, which provides a mechanical support to the die 4 itself; in particular, the die 4 is connected to the die-pad area 2 by means of an appropriate bonding paste, and is protected by a protective case (not shown), made of insulating material and forming part of the package 1. In addition, the package 1 comprises three leads 6, which enable connection of the die 4 to the outside world, and form, together with the die-pad area 2, the so-called lead frame 8. The package 1 further comprises a tab 10, which is made of metal material, is connected to the die-pad area 2, and defines a fixing hole 12.
In greater detail, each of the leads 6 has a respective connection terminal 14. By way of example, the connection terminals of two leads 6 set externally have a so-called “T” shape, so that they are generally known as “T-posts”.
Operatively, to enable proper operation of the die 4 and of the electronic circuits implemented therein, it is necessary to bond the die 4 itself with one or more of the leads 6. For this purpose, it is possible to resort, amongst other techniques, to the aforementioned wire bonds, clip bonds, or ribbon bonds.
As regards wire bonding, it is likewise possible to distinguish between thin-wire bonding and heavy-wire bonding; in either case, the bonding is carried out by means of an element of conductive material, having a circular section.
In the case of clip bonding, the bond is carried out by means of a so-called clip, i.e., a strip of conductive material (typically, copper), so as to obtain a quasi-planar bonding.
As regards, instead, ribbon bonding, bonding between the die 4 and at least one of the leads 6 is carried out using a sort of ribbon of conductive material, typically aluminum.
By way of example, FIG. 2 shows an example of ribbon bonding, inside an electronic device 15 formed by a die, designated once again by 4, and a respective package, designated once again by 1. Further elements, already shown in FIG. 1 and present also in the electronic device 15 shown in FIG. 2 are designated by the same reference numbers. For reasons of clarity, the protective case of the die 4 is not shown in FIG. 2 either.
In particular, the electronic device 15 comprises a first connection terminal 14a, a second connection terminal 14b, and a third connection terminal 14c, which respectively form part of a first connector 6a, a second connector 6b, and a third connector 6c; in addition, the electronic device 15 comprises a ribbon 16, made for example of aluminum, or else of aluminum-cladded copper.
In detail, the ribbon 16 is electrically connected to the first connection terminal 14a and to the die 4. In particular, the die 4 has a body 17, made of semiconductor material, and a metallization 18, which is set in contact with the body 17 and defines a top surface 20 of the die 4 itself. In addition, the ribbon 16 is electrically connected to the metallization 18 of the die 4, while a bottom surface 22 of the die 4, opposite to the top surface 20, is connected to the die-pad area 2 by means of a layer of bonding paste (not shown). In practice, the metallization 18, made, for example, of aluminum, defines the so-called front die, which is electrically connected to the first connection terminal 14a by means of the ribbon 16.
In greater detail, the ribbon 16 has a certain flexibility and has a first contact surface 24a, a second contact surface 24b, and a third contact surface 24c, which are to a first approximation the same as one another and substantially rectangular in shape. In particular, the first contact surface 24a is formed by the portion of the ribbon 16 effectively in contact with the first connection terminal 14a, while the second and third contact surfaces 24b, 24c are formed by portions of the ribbon 16 effectively in contact with the metallization 18 of the die 4.
The electronic device 15 likewise comprises a wire bond 26, which electrically connects the third connection terminal 14c to the die 4. In particular, the metallization 18 is shaped so that the wire bond 26 is electrically connected not to the metallization 18, but rather to the body 17 of the die 4. The second connection terminal 14b is, instead, formed integrally with the die-pad area 2, as well as with the tab 10.
Purely by way of example, the die 4 can house a power MOSFET 27, and the first, second, and third connection terminals 14a-14c can be electrically connected, respectively, to the source, drain, and gate terminals of the power MOSFET 27; in this case, the metallization 18 coincides electrically with the source terminal, whilst the die-pad area 2 coincides electrically with the drain terminal.
FIG. 3 shows a cross section of the ribbon 16, which has a rectangular shape and a width L and a thickness T. The thickness T is negligible with respect to the length (not shown) and to the width L of the ribbon 16; in particular, the thickness T is not greater than one third of the width L.
In general, the ribbon bonds are characterized by low resistances, and enable supply to the dies, or rather to the electronic circuits formed therein, of particularly high currents, hence representing a very flexible form of connection suitable also in the case of so-called power devices.
In greater detail, the ribbons designed to form the ribbon bonds are generally obtained by means of rolling of a conductive material (aluminum, cladded copper, etc.) into sheets having a thickness T; next, the sheets are cut in such a way that the ribbons thus obtained have the desired widths L. From a more quantitative standpoint, the ribbons available today typically have thicknesses T and widths L that are in a ratio with respect to one another of one to ten, or else of one to eight. In absolute terms, the maximum thickness Tmax and the maximum width Lmax of a generic ribbon are, respectively, equal to 10×80 mils, i.e., 0.254×2.032 mm.
In practice, in the technical field of packages of integrated electronic circuits, the ribbon bonds are obtained using ribbons the thickness T and width L of which are substantially standardized, according to the machines currently available for creating the bonds themselves, generally known as bonding machines. In particular, the aforementioned maximum width Lmax is set by the bonding machines currently available for providing wire bonds. In fact, it is common practice to use the same bonding machines to carry out both wire bonding and ribbon bonding; however, this is possible provided that the ribbons have widths not greater than the maximum width Lmax; otherwise, the bonding machines known today do not enable handling of ribbons in an appropriate way.
In detail, a generic bonding machine comprises, amongst other things, one or more guides, a bonding tool and a transducer. In practice, the guides are such as to bring a wire, in the case of wire bonds, or else a ribbon, in the case of ribbon bonds, in the proximity of at least one die, carried by a respective die-pad area. When the wire, or else the ribbon, is in the proximity of the aforementioned die, the connection tool exerts a pressure on the wire/ribbon, in such a way that it contacts the die, and in particular the metallization that forms the front die. In addition, the transducer transmits ultrasounds, which impinge on the portion of wire/ribbon in contact with the metallization of the die; in this way, by means of pressure and exposure to ultrasounds, there is partial melting of the conductive material that forms the metallization and the wire/ribbon, with consequent formation of the bond.
As has been mentioned, the ribbon bonds enable supply to the dies of particularly high currents; for example, a generic ribbon having a thickness T and a width L respectively equal to ten and eighty mils is able to withstand the same total current that can be conveyed by four round wires with a diameter of fifteen mils. Consequently, the ribbon bonds enable simplification of the electrical connections between dies and connection terminals. However, the ribbon bonds, and in particular the geometrical dimensions of the ribbons, should respect the geometrical constraints imposed by the bonding machines, with consequent limitation of the benefits that can be achieved adopting said type of bonding. | {
"pile_set_name": "USPTO Backgrounds"
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Conventional memory devices have a standard interface consisting of separate address, data and control pins. For example, one version of a synchronous dynamic random access memory (SDRAM has twelve address pins, two multiplexed address and control pins, seven control pins and sixteen data pins. This approach offers a great deal of flexibility since computer systems vary greatly in their memory requirements. In particular, the bandwidth of memory systems using SDRAMs can easily be increased by adding another SDRAM in parallel to the existing SDRAMs, thereby increasing the width of the memory bus.
The tradeoff for this flexibility is, however, an increase in layout space which leads to an increase in manufacturing cost. Separate traces need to be run for each pin of each SDRAM. Therefore, it is sometimes cost prohibitive to use SDRAMS for wide memory systems.
One approach to lower the cost of expanding memory is to use memory devices which multiplex address, control and data information on the same pins. For example, some memory devices have a set of generic interface pins which connect to a high-speed, synchronous bus. Communication over the bus is accomplished by a series of packets which conform to a predefined packet protocol. Usually the packet protocol is fairly sophisticated and has a complete command set. For example, DRAMS conforming to the RAMBUS.TM. interface communicate using a protocol in which each packet consists of six bytes transmitted sequentially over a high-speed bus known as a "Channel." In this manner, the packets encapsulate all address, control and data information.
Because of the efficient use of generic interface pins, a packet protocol reduces the required number of pins to approximately 30. However, this has the disadvantage of decreasing effective data bandwidth, because only a portion of the total bus bandwidth is available for data (the rest of the bandwidth is reserved for address and control information).
Another method for reducing the cost associated with increasing total memory bandwidth, without decreasing effective data bandwidth, is to provide a second high-speed bus specifically for communicating data In this approach, address and control information is communicated over a unidirectional high-speed address/control bus while data is communicated over a bidirectional high-speed data bus. Both communications conform to a predefined packet protocol. This approach has the benefits of reducing the total pin count (although not as much as the RAMBUS.TM. protocol described above), yet has the added benefit that only the data bus needs to be duplicated when the width of the memory system is increased.
Both approaches described above offer advantages over traditional memory architectures in terms of increased data retrieval bandwidth It is difficult, however, to implement systems having both fine granularity and large memory depth using such devices. What is needed is a memory architecture which supports increased bandwidth, fine granularity, and large memory arrays. | {
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Fluids, such as whole blood or various other biological fluids are suspensions and can be separated into their constituent parts or fractions. For example, whole blood comprises four main fractions, red blood cells, white blood cells, platelets and plasma, that can be separated based on their different specific gravities in a device such as a centrifuge. An anti-coagulated whole blood sample may be placed in a test tube, or other similar device, which is then spun in a centrifuge at a specified speed. The generated centrifugal force separates the blood into the different fractions based on their relative specific gravities. The red blood cells are on the bottom, plasma, is on the top with the intermediate specific gravity white blood cells and platelets (together referred to as the buffy coat) intermediate to the other two fractions. Various other biological fluids may be separated as well. For example, nucleated cells may be separated and extracted from bone marrow or adipose tissue derived samples.
It is desirable to isolate the different fractions of whole blood for differing medicinal purposes. The platelets can be obtained in preparations of platelet rich plasma (PRP) or platelet concentrates (PC). Platelets contain growth factors (e.g. PDGF, TGF-β, and others), which may initiate, aid in or accelerate various bodily functions, including but not limited to angiogenesis, wound healing, and osteogenesis. Administering autologous platelets to an injury site may improve the healing response by using a patient's own platelets without the risk of infection by using blood products from another donor source. Alternatively, platelet poor plasma (PPP) may be desired for use in various procedures. PPP may be prepared by isolating the plasma fraction from platelet concentrates, and preserving the isolated plasma fraction.
Various systems exist for the production of PRP/PC. Some use specialized test tubes, U.S. Pat. Nos. 7,179,391 and 7,520,402, that can include floats, tubing and/or gel materials of specific densities. Other systems use specialized double syringes, for example those found in U.S. Pat. Nos. 6,716,187 and 7,195,606. These test tubes and syringes must be centrifuged in a specialized large centrifuge for a specified time, typically 10-30 minutes, and then by delicate handling and extraction or decanting procedures produce the desired PRP/PC. The consistency of these preparations can vary depending on the operator's skill level. Other systems, for example U.S. Pat. No. 6,982,038, contain specialized centrifuge chambers and complicated control systems to produce the PRP/PC in about 30 minutes. All of these systems provide PRP/PC of differing platelet concentrations depending on the method used. A major drawback to these methods is the need for an expensive piece of capital equipment which limits the utility to facilities that have the funds and space available. These methods also require considerable operator skills to complete the procedures necessary to obtain the PRP/PC.
The ability to produce PRP/PC from a patient's own blood at the point of care without the need for complex, expensive equipment and difficult procedures would facilitate the clinical utility of PRP/PC. Therefore the objects of this invention include among other things providing an apparatus and method for processing a patient's own blood at the point of care in a short period of time that is self contained, battery operated, small and or portable, inexpensive, easy to use, reproducible, able to separate many cellular populations, and disposable without the need for additional centrifugation equipment. | {
"pile_set_name": "USPTO Backgrounds"
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Outside of using modern dishwashers, the most common technique used for washing implements such as utensils, cutting knives, or other tools or equipment, has been to hold the implement with one hand, and alternatively scrub the implement with a brush or sponge held by the other hand and rinse under running water from a faucet. In some cases, implements are allowed to soak first in a basin formed by a sink, a glass, or a bowl, to soften foodstuffs or dirt that sticks to the implements. Yet, even in these cases, the soaked implements must be scrubbed and washed using two hands as described above.
Further, when such basin is used, they are separate and removed from any scrubbing tool. The scrubbing tool may be set aside near the edge of a sink, in the sink, on the floor surrounding the sink, or in any of a number of locations removed from the basin. This separation leads to unnecessary difficulty and complexity in a process to wash implements, as well as requiring the user to use both hands during the washing process. | {
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1. Field of the Invention
The present invention relates to an attachment structure for a trim and a glass run. The trim is attached to a flange formed on the inner circumference of a window frame of a vehicle, and the glass run is attached to a door sash of the window frame so that the glass run guides a door glass to make the door glass slide on the glass run when the door glass is opened and closed in a window opening of the window frame. The present application is based on Japanese Patent Application No. 2000-43189, which is incorporated herein by reference.
2. Description of the Related Art
In the background art, a window frame of a side door of a vehicle is constituted by an inner panel, an outer panel and a door sash which are formed by press forming. To connect these members, flanges formed on the respective members are welded with each other. It is necessary to cover those flanges with a trim having a U-shaped section. A glass run to be attached into an attachment groove of the door sash is of an integral type in which the sectionally u-shaped trim is formed integrally, and others are of a separate type in which the glass run and the trim are formed separately.
In the case of the former, that is, in the case of the integral type, as shown in FIG. 11, a window frame 13′ is constituted by an inner panel 15′, an outer panel 16′, and a door sash 17′ attached between the inner panel 15′ and the outer panel 16′. A car-interior-side (hereinafter, simply referred to as “interior”) flange 17a′ of the door sash 17′ is welded with an inner-peripheral flange 15b′ of the inner panel 15′ in a condition that they are superimposed on each other. A car-exterior-side (hereinafter, simply referred to as “exterior”) flange 17b′ of the door sash 17′ is welded with a flange 16f′ of the outer panel 16′ in a condition that they are superimposed on each other. A glass run body 31a′ of a glass run 31′ is attached into a channel-like attachment groove 17c′, which is formed in the door sash 17′ by press forming. A door glass 14′ is inserted between seal lips 31b′ and 31c′ of the glass run body 31a′ so that the door glass 14′ can be guided by sliding on the glass run body 31a′. A trim 31d′ having a U-shaped section is formed integrally with the glass run 31′ so as to cover the interior flanges 15b′ and 17a′. In addition, a holding lip 31e′ also having a seal function is formed on the exterior side wall of the glass run body 31a′ so as to perform sealing between the glass run body 31a′ and a molding provided separately so as to cover the outside of the flange 16f′ of the outer panel 16′ (see Japanese Patent Publication No. JP-A-10-86668).
On the other hand, in the case of the latter, that is, in the case of the separate type, as shown in FIG. 12, a window frame 13″ is constituted by an inner panel 15″ and an outer panel 16″. A separate retainer frame 32″ (corresponding to the door sash 17″) also serving as a molding is attached to the outer panel 16″ by a clip 33″. Then, a glass run 31″ is attached into the retainer frame 32″. Meanwhile, a trim 34″ formed separately from the glass run 31″ and having a U-shaped section is attached to interior flanges 15b″ and 16f″ of the inner panel 15″ and the outer panel 16″ (see Japanese Utility model Publication No. JP-U-4-130514).
Since the trim 31d′ is formed integrally with the glass run body 31a′ in the former attachment structure for the glass run 31′, the number of parts can be reduced. However, the glass run 31′ increases in size as a whole so that there is a problem in the working of attachment to the window frame 13′. In addition, the interior flanges 15b′ and 17a′ of the inner panel 15′ and the door sash 17′ respectively perform sealing between the window frame 13′ and a door weather strip provided at a door opening edge of a vehicle body frame, at the inner peripheral edge of a corner portion of the window frame 13′. Accordingly, it is necessary to set the curvature radius of each of the flanges 15b′ and 17a′ to be large in accordance with the large curvature radius of a corner portion of the weather strip. On the contrary, each of the inner peripheral edges of corner portions of the outer panel 16′ and the door sash 17′ is set to have a small curvature radius in order to improve the external appearance. Incidentally, the above configuration will be made clear in FIG. 2, which shows an embodiment of the present invention.
From the point of view of realization in sheet metal working, however, it is difficult to set the curvature radius of the corner portion at the door opening edge of the vehicle body frame to be small in accordance with the curvature radius of the corner portion of the door sash 17′.
Accordingly, the glass run body 31a′ of the glass run 31′ and the trim 31d′ have different shapes in their corner portions so that each of molded portions of the corner portions has a complicated curved-surface structure and increases in size. Thus, there is a problem that it is difficult to form them by a molding method.
In addition, it is necessary to form the interior seal lip 31b′ to be large due to the integral formation of the trim 31d′ as shown in FIG. 11. Accordingly, it is difficult to balance the durability of the seal lip 31b′ with the sliding resistance when the door glass 14′ moves up and down.
Further, there is also a problem that the attachment of the glass run 31′ to the window frame 13′ is difficult in a corner portion so that it is difficult to set the glass run 31′ in a proper position.
On the other hand, in the latter separate-type attachment structure for the glass run 31″ and the trim 34″, the glass run 31″ and the trim 34″ are formed by separate members from each other. Accordingly, it is possible to form the glass run 31″ to be small as a whole, and it is also possible to mold a corner portion of the glass run 31″ easily. In addition, a corner portion of the trim 34″ can be formed only by bending an extrusion body formed by an extruding method.
In the latter attachment structure, however, the separate retainer frame 32″ is attached to the outer panel 16″. Accordingly, the retainer frame 32″ may shift in position due to an error in manufacturing and installing the outer panel 16″ and the retainer frame 32″. As a result, there arises scattering in the pressing force on a contact portion between the interior holding lip 31f″ of the glass run 31″ and the holding lip 34a″ of the trim 34″. Then, a shortage of the pressing force causes a failure in sealing, and a gap is formed so that the exterior appearance deteriorates. On the contrary, if the pressing force becomes excessive, the seal lip 31b″ of the glass run 31″ is displaced on the car-exterior-side. As a result, the seal lip 31b″ is intensely pressed on the door glass 14″ so that the sliding resistance increases when the door glass 14″ moves up and down. Thus, there is a problem that the door glass 14″ cannot be moved up and down smoothly. | {
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Steam power plants generally comprise a steam turbine and a boiler, wherein a steam line is designed and arranged such that steam generated in the boiler can flow to the steam turbine. The boiler can produce steam with a temperature of greater than 600° C. and a pressure of greater than 300 bar. Such high steam temperatures and pressures present a challenge to the valves arranged in the steam lines. In general, two valves, specifically a quick-closing valve and a control valve, are arranged in a steam line in which steam is conveyed to a steam turbine. The quick-closing valve is provided for quick closing in the event of a fault and is accordingly designed for this case. The control valve takes on the task of regulating or controlling the supply of steam through the steam line when the quick-closing valve is open.
In modern steam power plants, both quick-closing valves and control valves consist essentially of a valve housing and a valve cone, wherein the valve cone is able to move, by means of a valve stem, in one direction. Steam can flow between the valve stem and the valve housing, wherein this flow is a leakage flow and is therefore termed valve-stem leakage steam. The valve-stem leakage steam is generally collected and supplied to the steam power plant as seal steam.
The high temperatures and high pressures of the steam meant that, hitherto, no other use was possible. Introducing the valve-stem leakage steam for example directly into a condenser would not be possible since, under certain operating conditions, air is drawn into the valve and could therefore lead to possible damage in the valve. | {
"pile_set_name": "USPTO Backgrounds"
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1. Field of the Invention
The present invention relates to an identification system that uses a laser retro-reflecting and modulating set. The identification depends on the use envisaged for the system: it may be a measurement of the orientation of the laser beam with respect to a reference direction related to an illuminated object, or again it may pertain to the identification of the illuminated object.
2. Description of the Prior Art
The use of transmission means, working together to remotely illuminate a set that fulfils the functions of modulation and retro-reflection, is known in the prior art.
A solution of this type is described in the U.S. Pat. No. 4,134,008, which more especially emphasizes the making of a responser in a friend or foe identification system. According to this type of approach, an electro-optical modulator, such as an interference optical filter or a PLZT electro-optical switch is associated with a mirror to create the desired functions. In these methods, the re-transmitting part is combined with a receiver, itself designed to identify the already-encoded laser wave that is received.
According to another known method, described in the French patent No. 2 433 760, an object illuminated by a laser wave comprises retro-reflecting and modulating sets in which a PLZT ceramic is associated with a catadioptric device, such as a reflecting corner cube. The application envisaged is more especially the detection and location of an object and the spatial identification of directions related to the object.
An aim of the present invention is to propose another method for the retro-reflection and modulation of the laser beam, a method which, through the parameters brought into play, can be used in a variety of applications.
3. Summary of the Invention
In accordance with the present invention, there is provided an identification system using a laser beam retro-reflecting and modulating device, the said system comprising a laser transmitter/receiver which is mechanically separate and is placed remotely from a retro-reflecting and modulating set, the transmitter producing a radiation in the direction of the said set and the receiver comprising circuits for the detection and processing of the laser rays modulated and sent back by retro-reflection. The retro-reflecting and modulating set comprises an acousto-optical deflector which periodically receives an electrical signal from a control circuit. The frequency of the said electrical signal can be adjusted to obtain the diffraction of the beam in accordance with the operating conditions of Bragg's law. The deflector is mechanically coupled with a catadioptric device placed downstream to send back the diffracted laser radiation in the same direction and, after this radiation has passed through the deflector in the reverse direction, to produce the retro-reflection of the beam towards the transmitter/receiver, the retro-reflected wave having a frequency shift with a value equal to twice the frequency of the said control signal. | {
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Thousands of species of photosynthetic microbes are routinely cultivated at relatively small scale in the laboratory, in culture vessels ranging from several milliliters up to a few hundred liters in capacity. However, attempts to cultivate at larger scales, generally, necessary for commercial production, have proven successful for fewer than 10 species—despite a worldwide effort that has lasted half a century and consumed billions of dollars.
There are two basic types of culture vessels that have been employed in the effort to cultivate photosynthetic microbes at commercial scale: (1) Photobioreactors (Closed Systems), and (2) Open Systems.
(1) Closed Systems are characterized primarily by the provision of means to control access to the atmosphere. Gas exchange with the atmosphere is allowed to occur under controllable conditions. Carbon dioxide enters the culture vessel as a fuel for growth, and oxygen, the gaseous waste product of photosynthesis, is permitted to escape the culture vessel. (The carbon is assimilated into plant biomass, and the “dioxide”—oxygen—is expelled.) However, gas exchange occurs through filtration mechanisms that are designed to prohibit entry into the culture vessel of any species of photosynthetic microbe other than the one that is being preferentially cultivated therein.
Closed Systems are usually also designed to allow for the control of other environmental conditions. The provision for control of environmental variables such as temperature, pH, nutrient concentrations, and light makes it possible to optimize growth conditions for different species of microbial plants, which, like terrestrial plants, have distinct preferences for unique combinations of such variables.
For a given set of environmental conditions, all species of photosynthetic microbes grow at their maximum rate within a narrow range of cell concentrations. Accordingly, some Closed Systems are designed to operate as “turbidostats,” wherein the optical property of turbidity (opaqueness), which is a function of cell concentration, is monitored by means of programmable sensors that measure the optical density of the medium. The operator may specify a desired range of acceptable cell concentration, between a low value and a high value. The low value corresponds directly to a specific low optical density (the “low set point”), and the high value to a specific high optical density (the “high set point”). The optical density sensor is then programmed accordingly. When optical density attains a value that exceeds the designated upper set point, the turbidostat activates a control mechanism that provides for removing (harvesting) a fraction of the culture and replacing it with cell-free nutrient medium, thereby diluting the cell concentration to yield a value of optical density that matches the designated lower set point. The cells then will grow, increasing in concentration until optical density attains a value that once again exceeds the upper set point, at which time the cycle repeats.
Preferably a Closed System culture vessel is constructed primarily of transparent material, such as glass or plastic, that allows the transmission of photosynthetically active radiation (visible light), but which otherwise separates the culture medium from the atmosphere. Culture vessels may take many different shapes, but they all share in common one spatial dimension that limits their performance, and that is their depth relative to incident light intensity. This feature arises from a basic property of photosynthesis, namely, that photosynthetic rate is limited by light intensity. Thus, at any given light intensity, the rate of photosynthesis of a cell culture is maximized as a function of the Lighted Area, i.e. the area of the culture medium that is exposed to light (not necessarily the Surface Area, which may include areas of the culture vessel that are not exposed to light). Consider two culture vessels, both outdoors and exposed to sunlight. One is in the shape of a rectangular pond with solid sides and bottom, and the second is in the shape of a transparent cylinder, placed horizontally on top of the ground. For the rectangular pond the Surface Area includes the top, bottom, and sides of the pond, but only the top area of the culture medium is exposed to sunlight. For such an outdoor pond, then, the Lighted Area is equal to less than half the Surface Area. By comparison, for the transparent cylinder, the Surface Area is the entire surface of the cylinder and, no matter what the time of day, half of the Surface Area will always be directly illuminated by sunlight. Thus, for the cylinder, the Lighted Area is equal to half the Surface Area
A second factor affecting the relationship between photosynthesis and light is the cell concentration in the culture medium. The greater the cell concentration within a medium, the less the depth to which light may penetrate, because light penetration decreases approximately exponentially as a function of cell concentration. In other words, if the cell concentration increases at a constant rate, light disappears faster and faster. At some depth in a cell culture, then, light will actually decrease to zero.
As a practical matter, the optimal culture depth for photosynthetic microbes exposed to full sunlight is generally in the range of 10 to 20 centimeters. No advantage can be gained by providing greater depth of the culture, because the concentration of cells per unit Lighted Area will remain the same, and deeper cells will not receive enough light. The optimal depth, then, puts a limit on the normal operating capacity of any culture system, regardless of its Lighted Area. This phenomenon is a critically important feature in the design of cultivation systems. Greater volumes require more, materials, at greater cost, but at some point the increase in volume provides no increase in productivity per unit Lighted Area.
Cultures of photosynthetic microbes generally require stirring or mixing in order to maintain a homogeneous distribution of cells in the medium. The natural tendency of photosynthetic microbes in still water is to form dense aggregations, within which the properties of the medium are altered to the detriment of the culture. On a microscale, within the aggregation, the availability of light and the concentration of nutrients and gases become so different from the remainder of the medium that growth is limited. Some species have appendages known as cilia or flagellae that allow them to swim; such motile (“moving”) species actively form aggregations. Most non-motile species are heavier than water and will sink, forming a passive aggregation on the bottom. To prevent such aggregations, Closed Systems must provide a means for creating turbulence using devices such as airlifts or pumps.
(2) Open Systems differ from Closed Systems in one critical feature, namely that they are open to the atmosphere. This feature is advantageous to both construction and operation, in several ways. First, because the Lighted Area of an Open System is exposed directly to sunlight, there is no requirement to use a transparent material to construct the culture vessel; this affords broad latitude in the choice of materials. Second, because no material is used to cover the Lighted Area of the Open System, the amount and cost of material is reduced by about half. Third, Open Systems are generally easier to clean than Closed Systems. Over time the inner surface of any culture vessel will tend to accumulate a film of microbial growth. In a Closed System the accumulation of such a film on the Lighted Area will absorb light; the consequent decrease in light intensity causes a decrease in productivity. In both Open Systems and Closed Systems the culture vessel surface can accumulate microbial films of undesirable species that may be detrimental to growth and production of the desired species. In either case, the culture vessel surface will require cleaning from time to time. As a practical matter, Open Systems allow a much wider choice of cleaning methodologies. For example, people and large types of mechanical cleaning equipment such as hoses, pressure washers; and scrubbers that cannot enter the confined space of a Closed System can easily enter an Open System.
The principal disadvantage of an Open System is that, by being open to the atmosphere, it is susceptible to contamination by unwanted species. One may begin the operation of an Open System culture with only one desired species of photosynthetic microbe. However, undesired species will inevitably be introduced, whether by atmospheric transport or other means. Any undesired species that grows faster than the desired species in the same environmental conditions will, over time, outcompete the desired species and will ultimately dominate the culture.
In summary, Closed Systems are designed specifically to prohibit contamination by undesired species, with the expectation that continuous cultivation of a desired species may be possible for a much longer period than would be possible in an Open System. However, Closed Systems are more complicated to construct and operate. Open Systems afford a wider choice of materials for construction, and also afford a wider choice of cleaning methodologies. Closed Systems require additional operating practices, such as the use of sterile technique during fluid transfers, which call for greater time and expertise on the part of the operator.
Theoretical differences between Closed Systems and Open Systems have been borne out in practice. The first photosynthetic microbe was isolated from nature and grown in pure culture little more than a hundred years ago, but it was not until the late 1930s that sufficiently large volumes of a single species could be cultivated to permit chemical analysis. By the 1940s various species were being grown in laboratory cultures of about 25 liters, and it was discovered that, by altering environmental conditions of the culture, either the oil or protein content of some species could be made to exceed 60% of the total cell mass.
The first attempts at large-scale cultivation began in the 1950s, stimulated by widespread interest in photosynthetic microbes as a source of cheap protein for foods and animal feeds. The first Open Systems, built in Germany, took the shape of shallow, elongated, recirculating raceways, with flow provided by a paddlewheel device. Nationally-funded programs developed rapidly throughout the world, all following the German “open pond” design. The first open ponds had capacities of just a few thousand liters. By the late 1950s, capacities of almost 100,000 liters had been attained and, by the late 1960s, almost 1,000,000 liters. Such increases in capacity brought economies of scale.
Hundreds of species were tested in the laboratory, and attempts were made to grow the best protein producers in open ponds during the 1960s and 1970s. Only a few species proved to be amenable to sustained cultivation. These few species, such as Spirulina platensis and Dunaliella salina, went on to become the basis of commercial production, effected in open pond systems covering hundreds of acres. The successful commercial species proved to be “extremophiles,” which thrive in conditions of unusually high pH or salinity. Most species prefer conditions that prevail in nature, where numerous species thrive simultaneously. For two decades, all attempts to cultivate single-species cultures of non-extremophiles in open ponds failed after less than a few months because they were contaminated by other species that thrived under the same environmental conditions.
Renewed interest in large-scale cultivation was stimulated in the 1980s and 1990s by the prospect of producing renewable biofuels using oils from photosynthetic microbes as a feedstock. During this period government agencies of the USA and Japan, for example, invested approximately $150 million in such an effort. Such programs shared two goals: first, to collect and identify species of photosynthetic microbes that produce high concentrations of oil and then to determine the environmental conditions under which they do so; and, second, to design and demonstrate the operation of large-scale cultivation systems for the production of biofuel feedstocks using species that had been developed in the laboratory. Both programs succeeded at the first goal, but failed at the second.
Laboratory studies quantified earlier findings. Culture collections of hundreds of species were amassed. Research on numerous strains demonstrated that, in general, nitrogen sufficiency (nitrogen is needed for protein synthesis) promoted high growth rates and low oil content, whereas nitrogen deficiency resulted in low growth rates and high oil content. For some species, it has also been noted that stress, caused by factors such as high light intensity or very high temperatures, can induce species to shift from protein synthesis to oil synthesis. Species capable of optimal oil production—the highest oil content at the highest growth rate—were selected for large-scale production trials.
Large-scale production was once again attempted in the late 1980s and early 1990s using open pond systems. Operating results were similar to those obtained for the three previous decades. Promising oil-producing species were selected from the collections, and cultures were inoculated into the ponds. However, as in prior experience, single-species cultures could not be maintained for more than a few weeks or months. The final report of the US program referred to this phenomenon as an “uncertainty with the nature of species control achieved.”
By the 1990s the status of large-scale cultivation had not progressed beyond the point reached in the 1960s. Three types of microalgae—Spirulina, Dunaliella and Chlorella were being cultivated at facilities using open pond systems covering more than 100 acres. Scores of other species had been attempted worldwide, but all attempts had failed. The biofuels programs, in particular, had been unable to grow any desired species at any scale outside the laboratory. Moreover, the biofuels programs had focused on attempts to demonstrate the highest possible biomass production rates under nutrient-sufficiency, conditions that are known from laboratory studies to favor low oil content. No attempts were made at large-scale to maximize oil production.
Large scale Closed System technology began to receive significant attention in the early 1990s, once it became evident that cultures of most species exposed to atmosphere were not sustainable. At that time, the largest Closed Systems that had ever been used were no more than a few thousand liters in capacity. Advances in the past decade have succeeded at increasing reactor capacity by a factor of about 10, to about 30,000 liters. But this is nowhere near the rate of increase achieved for Open System capacity that, also over a decade (in the 1950s to 1960s), increased by a factor of 1,000.
The upper limit of Closed System capacity is, in large part, a direct consequence of inherent design requirements. All basic Closed System designs in use today were first developed in the 1950s, and may be categorized as follows: (1) vertical bags, tubes, or towers; (2) flat-plate reactors; and (3) horizontal tubes. Vertical systems are constrained by height limitations. Even when exposed to full sunlight, most cultures achieve such high cell densities that light is almost entirely absorbed at a distance of more than 15 to 20 cm from the Lighted Area. This constraint limits the diameter of the culture vessel to no more than 30 or 40 cm. To achieve a capacity of more than 10,000 liters, for example, a 40-cm diameter vertical system would have to be more than 80 meters (260 feet) high. Such dimensions present clear challenges in structural engineering which, even if achievable, become increasingly complex the greater the volume of the system. One of the obvious solutions has been to introduce an illumination system within the reactor, but experience has shown that this introduces other problems, of which bio-fouling may be the greatest. Over a relatively short time, the surface of the light source tends to become covered with a microbial film, sharply reducing light intensity and thus defeating the purpose of the light source. Removing the culture and cleaning the vessel is one option, but hardly desirable if the goal is sustained operation. Another common anti-fouling option, making the surface of the light source toxic to microbes, is clearly undesirable. In general, the use of internal illumination makes the system more complex.
Horizontal systems such as flat-plate reactors and horizontal tubes eliminate the need for the structural engineering required of vertical systems. Using the earth's surface for structural support, the potential capacity of such systems might appear limitless. However, the capacity of horizontal systems is generally limited by the requirement for turbulent flow, whether used to maintain adequate mixing or to fill and empty the culture vessel.
Turbulent flow in a pipe or a channel is described by the Reynolds number, defined as the velocity of the fluid multiplied by the “characteristic length” of the pipe or channel, and divided by the viscosity of the fluid. The Reynolds number does not have any units, like inches or pounds, and is therefore “dimensionless,” like “one-half” or “two-thirds”. The characteristic length of a fluid-filled pipe is its diameter; the characteristic length of a wide channel is its depth. For a fluid of constant viscosity, flow will become increasingly turbulent as the velocity of flow increases. Turbulence also increases in proportion to the characteristic length; this happens because pipe and channel surfaces are “sticky.” Surfaces cause friction that slows down the flow; the flow rate is almost zero next to the surface, and increases with distance away from the surface. Thus, in a pipe or channel with small characteristic length, the surface friction will have a great effect on the average flow. By contrast, in a pipe or channel with large characteristic length, the surface friction will have little effect on the average flow, and turbulence will be greater.
Surface friction also adds up over distance. Imagine a very long pipe through which water is propelled by a pump. At the origin, near the pump, the flow is turbulent. The farther the fluid moves down the pipe, the more surface it is exposed to and, the more surface it is exposed to, the more its flow is slowed by friction. At some point from the origin, the accumulated friction has removed so much energy from the fluid flow that it ceases to be turbulent. This happens when, the Reynolds number falls below a value of about 2000, and then the flow is said to be “laminar.”
Laminar flow is not desirable in cell cultures because in such conditions the cells have a tendency to aggregate, either by sinking or swimming. Turbulent flow prevents such aggregations. Imagine, for example, how sand particles would rapidly sink to the bottom in a still pond, but would not do so in a large breaking wave or a rapidly moving stream.
In summary, then, turbulent flow is maintained by avoiding very low fluid velocities, very small characteristic lengths, and very long channels. The characteristic length for horizontal Closed Systems such as flat-plate reactors or horizontal tubes is the depth of the culture, which, as explained previously, has a practical upper limit of about 20 cm. One can create turbulent flow in a flat-plate reactor or a horizontal tube with any number of devices such as pumps or airlifts. However, with increasing distance from the origin of the flow, turbulent energy is lost to friction such that, at some finite distance flow becomes laminar. In laminar flow conditions the cells of most photosynthetic microbes will sink to the bottom of the reactor. This is undesirable for many reasons, not the least of which is that harvesting the cells becomes problematical. One solution is to provide more turbulent energy at the source, but this is acceptable only to an upper limit where mechanical shear damages the cells themselves. Yet another solution is to provide multiple pumps, for example, throughout the reactor, but this approach introduces additional complexities of both construction and operation.
As a matter of practice, vertical Closed Systems are limited to a capacity of less than about 1,000 liters, and horizontal Closed Systems appear to be limited to capacities less than about 50,000 liters. For the purpose of large-scale cultivation of photosynthetic microbes, Closed Systems are much more costly and complex to construct and operate than Open Systems. This is because each independent system requires its own independent infrastructure: a set of devices or mechanisms for providing turbulent mixing, introduction and removal of medium, and monitoring and control of variables such as pH and temperature. To cover a given area of land with Closed Systems requires at least 10 times more infrastructure than covering the same area of land with Open Systems, rendering Closed System cultivation much more complicated.
In practice, every cultivation system for photosynthetic microbes involves a coupling of both Open Systems and Closed Systems at some scale. All cultivation systems, regardless of scale, ultimately depend for their original inoculum of cells on culture collections routinely maintained around the world. All culture collections exclusively maintain their cell cultures in Petri dishes, test tubes, or sterilized flasks—all of which are, strictly speaking, Closed Systems. Even large-scale production systems that might be considered to consist “purely” of Open Systems must rely ultimately on a Closed System to supply the original inoculum.
The main technical conundrum for the production of photosynthetic microbes is that Open System technology has advanced to a large scale that is economical and relatively easy to operate, but cannot provide sustainable production of desired microbes. By contrast, Closed Systems do provide sustainable production of desired microbes, but even at their largest scale they are costly and complicated to operate.
Thus, there is a need for a production method that provides for sustainable production by reducing the potential for contamination and yet does not substantially increase the complexity or cost of construction or operation.
It is therefore an object of this invention to provide an effective method for sustainable production of photosynthetic microbes at large scales that may be easily constructed and does not increase the complexity or cost of construction or operation.
It is a still further object of this invention to provide a method of production that is especially suited to optimizing the production of oils and other useful products from photosynthetic microbes. Oils and other useful products may then be extracted and purified from the aggregate biomass by means of a variety of chemical methods. | {
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As one of methods for charging the surface of an electrophotographic photosensitive member, a contact charging method is currently practical.
The contact charging method is a method in which a voltage is applied to a charging member situated to be in contact with the electrophotographic photosensitive member to cause a very low level of electrical discharge near a contact area between the charging member and the electrophotographic photosensitive member, whereby the surface of the electrophotographic photosensitive member is charged.
For the charging member for charging the surface of the electrophotographic photosensitive member, those comprising a support and an elastic layer (conductive elastic layer) provided on the support are commonly used in terms of securing a nip of contact between the electrophotographic photosensitive member and the charging member.
The elastic layer (conductive elastic layer) often contains a relatively large amount of low molecular weight components, and therefore for the purpose of inhibiting the low molecular weight components from bleeding out to contaminate the surface of the electrophotographic photosensitive member, the conductive elastic layer is often provided thereon with a surface layer which is different from the conductive elastic layer and has an elastic coefficient smaller than that of the conductive elastic layer.
As for the shape of the charging member, roller-shaped charging members are commonly used. Hereinafter, the roller-shaped charging member is also referred to as “charge roller”.
The method which is most widely used among contact charging methods is a method in which a voltage with an alternating current voltage superimposed on a direct current voltage is applied to the charging member (hereinafter also referred to as “AC+DC contact charging method”). In the case of the AC+DC contact charging method, a voltage having a peak-to-peak voltage twice or more than twice as high as a charge starting voltage is used for the alternating current voltage.
The AC+DC contact charging method is a method enabling highly uniform and stable charge to be done by using the alternating current voltage, but use of an alternating current voltage source incurs upsizing of a charging apparatus and an electrophotographic apparatus and an increase in cost compared with a method in which a voltage with only a direct current voltage is applied to the charging member (hereinafter also referred to as “DC contact charging method”).
Namely, the DC contact charging method is a charge method which is excellent in terms of downsizing of the charging apparatus and the electrophotographic apparatus and a reduction in cost compared with the AC+DC contact charging method.
Japanese Patent Application Laid-Open No. 2003-107927 discloses a transfer member having a dynamic friction coefficient of 0.4 or less and surface free energy of 35 dyn/cm or less. | {
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1. Field of the Invention
This invention relates to methods of storing and accessing data on digital computers, and in particular, to an improved data base system for organizing large amounts of data for fast retrieval and processing.
2. Description of the Prior Art
Databases are used to store large amounts of data in digital computers. To analyze this data, users need to be able to identify sets of records based on a combination of attributes and generate summary information, such as sums, averages, and other statistical functions, for these sets.
Traditional databases may provide support for identifying some of these sets, but not all of them in an efficient manner. Multidimensional databases can provide fast access to more sets, for a small number of attributes. Even so, providing summary information on a set requires accessing all elements of that set, and is a time-consuming operation for large sets thereby delaying interactive queries for this information.
The following U.S. Patents disclose typical database management systems.
U.S. Pat. No. 4,554,631, entitled "Keyword Search Automatic Limiting Method." PA1 U.S. Pat. No. 4,606,002, entitled "B-Tree Structured Data Base Using Spare Array Bit Maps to Store Inverted Lists." PA1 U.S. Pat. No. 4,611,272, entitled "Key-Accessed File Organization." PA1 U.S. Pat. No. 4,468,728, entitled "Data Structure and Search Method for a Data Base Management System." | {
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Optical modules are optical transceivers or optical transponders which integrate components for the purpose of transmission and reception of optical signals into a single packaged device. The integrated components generally serve to convert electrical signals to optical signals and optical signals to electrical signals. Optical modules are used in applications requiring digital optical transmission such as SONET/SDH, Gigabit Passive Optical Networks (GPONs), Ethernet Passive Optical Networks (EPONs), Ethernet, and Fibre Channel running across metro access networks, campus area networks, wide area networks, access networks, local area networks, and storage area networks.
As shown in FIG. 1, an optical module 110 comprises of: a laser or laser diode 102 that converts an electrical input signal into an optical output signal, an optical detector or photodiode (PD) 103 that converts an optical input signal into an electrical output signal, and high speed integrated circuits (IC) such as: a laser driver (LD) 104 that takes an input signal and generates an electrical signal that modulates the laser 102, a transimpedance amplifier (TIA) 106 that converts the current output of the optical detector 103 to a voltage as large as possible with a relative minimum of electrical noise, and a limiting amplifier (LA) 106 that converts the TIA output to a suitable electrical level for signal processing. Some high speed optical modules also incorporate serializer and deserializer (mux/demux) 108 functions as illustrated in optical module 112. A serializer multiplexes multiple parallel slow rate digital data streams into a single high speed digital stream and a deserializer demultiplexes a single high speed digital stream into multiple parallel slower rate digital streams. Serializers typically incorporate a clock multiplier unit (CMU) that converts a parallel input clock signal into a serial output clock signal and deserializers typically incorporate clock data recovery (CDR) functions that recover a clock signal from a serial analog data stream.
Manufacturers of optical networking systems find optical modules attractive, because the highly integrated packaging approach can cut several months of system development and manufacturing time, consume less power and increase port densities over board-level solutions built from discrete components. But with so much functionality in one module, timely and sufficient component supply becomes even more essential for successful system delivery. Multi-source agreement (MSA) developed so systems vendors can feel more confident about getting the components they need and being able to incorporate them without costly and time-consuming system redesigns. MSAs define specification for an optical module such as: physical dimensions or cage hardware, electrical connector interfaces, electrical levels, jitter, power supply, max power draw, EMI containment, optical connector interfaces, and thermal analysis.
Further with MSAs, system vendors can concentrate on system architecture and not optical research and development. However, this also limits the usefulness or utility of MSAs to solely be optical-to-electrical and electrical-to-optical conversion devices.
Examples of the MSA optical modules are shown in FIG. 2, such as small form factor pluggable (SFP) 210, 10G small form factor pluggable (XFP) 212 and XENPAK 214. An example of MSA optical modules used in a passive optical network (PON) is shown in FIG. 3. In a PON 300, an optical line terminal (OLT) 311 communicates with optical network units (ONUs) or optical network terminals (ONTs) 314 at or near customer premises 305 (e.g., residential homes, business, schools and government buildings) over optical fibers 306 and through optical splitters 310. OLT's 311 and ONUs/ONTs 314 can communicate by using MSA optical modules 302 (e.g., SFP) to generate optical signals. OLTs 311 are generally located at a Service Provider's Central Office 304 and communicate with Edge Routers 312. | {
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1. Field of the Invention
The present invention relates to a system, server, client, method, and program for detecting whether or not the state of a client matches a predetermined state stored in a server.
2. Description of the Related Art
There are systems in which a server monitors the state of a client, and generates a warning when the state is not in a predetermined state. In this case, the server has to periodically acquire the state of the client, and determine whether or not the state of the client is the predetermined state.
However, when a server periodically acquires and monitors the state of a client, there is a possibility that the state to which the client is transitioning can be estimated on the server side.
Also, there is a method for checking whether or not a string possessed by a client has been accepted by an automaton possessed by a server which is called oblivious automaton evaluation. Oblivious automaton evaluation is a method where the checking process is executed without disclosing the string possessed by the client to the server and without disclosing the automaton possessed by the server to the client. Because the state of the client is oblivious to the server when this checking method is used, the state of the client is not estimated.
However, in oblivious automaton evaluation, the checking process has to be executed each time by returning the automaton to its initial state and transitioning in successive order through the states of the automaton. Therefore, when the state of the client is periodically monitored, the amount of transitioning (processing) increases as time elapses and the processing burden is more substantial. | {
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Development of wireless local area network (WLAN) standards such as the Institute for Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, and 802.11n Standards, has improved single-user peak data throughput. For example, the IEEE 802.11b Standard specifies a single-user peak throughput of 11 megabits per second (Mbps), the IEEE 802.11a and 802.11g Standards specify a single-user peak throughput of 54 Mbps, and the IEEE 802.11n Standard specifies a single-user peak throughput of 600 Mbps. Work has begun on a new standard, IEEE 802.11ac, that promises to provide even greater throughput.
Work has begun on a two new standards, IEEE 802.11ah and IEEE 802.11af, each of which will specify wireless network operation in sub-1 GHz frequencies. Low frequency communication channels are generally characterized by better propagation qualities and extended propagation ranges compared to transmission at higher frequencies. In the past, sub-1 GHz ranges have not been utilized for wireless communication networks because such frequencies were reserved for other applications (e.g., licensed TV frequency bands, radio frequency band, etc.). There are few frequency bands in the sub-1 GHz range that remain unlicensed, with different specific unlicensed frequencies in different geographical regions. The IEEE 802.11ah Standard will specify wireless operation in available unlicensed sub-1 GHz frequency bands. The IEEE 802.11af Standard will specify wireless operation in TV White Space (TVWS), i.e., unused TV channels in sub-1 GHz frequency bands. | {
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An electronic device generally includes an enclosure and a plurality of plug-in members mounted in the enclosure. Each plug-in member is mounted to the enclosure with a plurality of screws. | {
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This invention relates to an aquatic floatation mat or cushion providing sufficient buoyancy to permit a person to lie on the mat in water.
Aquatic mats now used for recreation and sports purposes are generally of the inflatable type. Although the inflatable types are satisfactory, they require the task of inflating them prior to use and deflating them after use. Furthermore, inflatable types can easily be punctured, ripped or torn. This will require patching, and if the tear or rip is large enough and cannot be patched, will render the mat useless.
The floatation mat of the present invention constitutes an improvement over inflatable mats by eliminating the requirement for inflation and also eliminating the problem of punctures, rips and tears.
It is an object of this invention to provide a novel aquatic mat with a headrest having a simplified construction, which is capable of floating on water, and which can support one or more persons.
It is another object of this invention to provide a novel aquatic mat having a headrest wherein the entire mat is manufactured from buoyant flexible, resilient slab materials.
Another object of this invention is to provide a novel buoyant, aquatic mat having a headrest for supporting a person's head containing one or more transverse open voids, which provide additional buoyancy to the headrest.
A further object of this invention is to provide a novel buoyant aquatic mat having a headrest containing an enclosed transverse chamber or chambers.
An additional object of this invention is to provide a novel buoyant aquatic mat having a headrest containing an enclosed chamber or chambers wherein the bottom of the headrest chamber has vent holes for providing equalization of pressure in the chamber and for providing additional buoyancy to the headrest.
Generally the buoyant aquatic mat comprises an elongated, flexible, resilient, planar slab member and a headrest member containing a transverse void formed from the same material as the planar slab member. The slab material comprises a unicellular, non-water absorbent plastic foam having a tough, plastic coating over the entire surface of the slab. Several embodiments of the mat are described. Furthermore, a modification adaptable to all the embodiments of the mat comprises slab material enclosing the ends of the void of the headrest forming an air chamber. An additional modification of the headrest with enclosed chambers is the provision of vent holes disposed through the bottom of the headrest communicating with the air chamber.
Other features and advantages of the various embodiments of the aquatic mat of the invention will become apparent from the following description of specific embodiments thereof taken in conjunction with the drawings. | {
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1. Field of the Invention
The invention relates to a capstan for use in a magnetic tape transport system, and more particularly to a capstan which has a low mass and a very low moment of inertia to diameter ratio.
2. Description of the Prior Art
There are many capstans presently in use in magnetic tape transport systems for accelerating a length of magnetic tape. U.S. Pat. No. 3,261,563 entitled Magnetic Tape Reel Control Servo System, issued to Jesse I. Aweida, Donald K. Close and Henry C. Pao on July 19, 1966, teaches a magnetic tape transport system which accelerates a length of magnetic tape to 200 inches per second (ips) in 0.065 inches of magnetic tape. There are three variables, moment of inertia (I), torque (T), and radius of the capstan (R.sub.c), in the equation for determining linear acceleration of a length of magnetic tape. The equation determining linear acceleration (a) is: EQU a = [(T/I) .times. 2 R.sub.c ].
The larger the radius of the capstan (R.sub.c) is, the higher its linear acceleration (a) will be for a given torque (T) and a given moment of inertia (I). Similarly, the lower its moment of inertia (I) is, the higher its linear acceleration (a) will be for a given torque (T) and a given radius of the capstan (R.sub.c). The advantage of a capstan having a relatively large radius with a lower moment of inertia is that a capstan motor which drives the capstan may achieve a higher acceleration performance with the same power input, or conversely, the capstan motor may achieve the same acceleration performance with a lower power input. The capstans presently in use that have low moments of inertia have small radii; conversely, the capstans presently in use that have larger radii than the capstans having low moments of inertia have high moments of inertia.
U.S. Pat. No. 3,122,295, entitled Web Transport, issued to Richard H. Davison, John G. Simon and James O. Esselstyn on Feb. 25, 1964, teaches a capstan with a grooved surface for generating a proper air bearing between the capstan and a length of magnetic tape. U.S. Pat. No. 3,143,267, entitled Tape Handling Device, issued to Alexander R. Maxey on Aug. 4, 1964, teaches a capstan constructed as a hollow cylindrical pressure housing, the cylindrical walls of which are formed of a porous material and the interior cavity of which is coupled to through a hollow capstan drive shaft. This capstan also has a number of circumferential grooves formed in parallel planes normal to the axis of the capstan.
Most capstans are made of a lightweight metal such as aluminum in order to provide the necessary strength. However since almost all metals including aluminum have a relatively high elastic modulus, a metal capstan may be required to have considerable mass to maintain the required structural integrity while shipping, assembling and otherwise handling the capstan. If the capstan is too thin or is overloaded so as to exceed its elastic limit, the capstan will become bent or otherwise permanently distorted and thereby rendered useless. In effort to achieve low inertia by minimizing the amount of material used for construction, the strength of a conventional capstan is often reduced to such an extent that the mere inadvertent dropping of such a capstan on a hard surface if often enough to damage the capstan beyond repair in view of the close tolerances involved.
U.S. Pat. No. 3,930,603, entitled Low Inertia Capstan, issued to Frederic F. Grant on Jan. 6, 1976, teaches a capstan formed principally of thin plastic so as to decrease its mass and inertia several orders of magnitude with respect to metal capstans of comparable size without increasing its susceptibility to damage. At the same time however such capstan are constructed so as to possess the necessary strength and rigidity in a circumferential direction in which accelerating torques are applied. The inherent elasticity and thinness of the plastic parts of the capstan enable the capstan to undergo substantial resilient deformation in other than circumferential and radial directions exceeding its elastic limit while the design shape provides substantial resistance to significant deformation in the circumferential and radial directions as a result of tape forces. The capstan includes a pair of extremely thin resiliently deformable plastic webs of partially conical configuration. The webs are mounted on the opposite ends of a generally cylindrical inner hub which is substantially of plastic construction and which is rotatable about a central axis thereof. The webs are so arranged as to be separated from one another by a maximum distance at the inner hub and to draw closer together in directions toward their outer edges which support a very thin, hollow, generally cylindrical outer rim of plastic construction. The mass and resulting inertia may be even further minimized by cutting out and removing portions of the webs to define a plurality of spokes. The outer rim may be formed by turning on a lathe and finish grinding or alternatively by vacuum deep drawing.
The moment of inertia of an object is related to the mass (m) of the object and the distribution of the mass about an axis. Generally, the moment of inertia may be approximated by the equation: EQU I = [k .times. (m) .times. R.sub.o.sup.2 ]
where k is generally a coefficient varying between 1/2 and 1 and R.sub.o is the radius of the object. It is therefore a matter of logic that in order to reduce the moment of inertia of the object one must reduce either its mass or its radius. Reducing the radius of the object results in lowering the moment of inertia, but the lower moment of inertia is partially offset by the smaller radius which results in a higher angular acceleration to achieve the same linear acceleration. Reducing the mass of the object also lowers the moment of inertia, but the object loses structural strength as a result of lowering its mass.
Each of the prior art capstans includes a pair of discs, each of which is formed from a substantially thin, metal or plastic material and which is of a particular diameter, and a cylindrical tape band, which is of a diameter the same as the diameter of the discs. The tape band has a number of air holes distributed throughout its face so that a vacuum supply may pull the magnetic tape against the tape band and create friction between the tape band and the magnetic tape. The necessity of these air holes requires that additional mass be added to reinforce the capstan near its tape band because the air holes weaken the structural strength of the tape band. Further compounding this structural reinforcement problem, requiring additional mass, is that the discs must also be airtight in order for the vacuum supply to operate. This additional requirement means that the discs may not have any mass, unnecessary for adding to the structural strength of the capstan, removed.
In operation these vacuum holes cause air to flow unevenly over the tape band creating a non-uniform gap between the magnetic tape and the tape band. The non-uniform gap slows the acceleration of the capstan and also produces an uneven acceleration. In order to fabricate this type of capstan the two discs are bonded together to the tape band to form an air-tight assembly. This fabrication process is relatively expensive.
Another type of prior art capstan uses an adhesive coating on its cylindrical tape band to frictionally drive the magnetic tape, but there is no way to reduce this friction to zero as there is with a reversible air flow supply. All these surfaces of both types of the tape bands are presently machined to high tolerances by precision tooling in order to minimize speed variations. Furthermore, not only is the structural strength of the tape band critical to the durability of the capstans, but also the distribution of its mass is critical to the performance of the capstans in magnetic tape transport systems.
As a result of aerospace technology there are processes wherein a platen, which is formed from a material that is dissolvable in a selected solution, is plated with a material that is not dissolvable in selected solution. Some of the more common material forming the platen includes aluminum, soap, sodium bicarbonate, the non-active ingredients of pills which dissolve in water and which may be temporarily protected by a protective coating, or any other material which can be dissolved or etched away by a selected solution. Some of the more common plating materials include titanium, nickel, magnesium, aluminum and various plastic materials. However, the designs of the prior art capstans make this plating and dissolving or etching process unfeasible because there are manufacturing problems inherent in the vacuum hole design. | {
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The present invention concerns a process for the cyclization of orthobenzoylbenzoic acid (OBB acid) in the presence of superactive bleaching earth in order to produce anthraquinone.
It is known to form anthraquinone from OBB acid by heating this acid compound in the presence of concentrated sulfuric acid or an oleum. Such a method is, for instance, reported by Arthur I. VOGEL in "Practical Organic Chemistry", 3rd edition, page 740. The sulfuric acid plays the role of catalyst and solvent for the reaction.
The concentrated sulfuric acid can be replaced by concentrated phosphoric acid or by phosphorus pentoxide. In each of the methods cited above, the large quantity of reagent utilized decreases the efficiency of the corresponding process and creates important pollution problems due to the discarded acid material.
Japanese Patent Application No. 49.7260/74 proposes working with a lesser amount of sulfuric acid, but the operation must then take place in a vacuum and at an elevated temperature above 300.degree. C. This causes operating risks and a high cost for the equipment due to corrosion inherent in the conditions of implementation of such a process. In addition, the recovery by sublimation of the anthraquinone formed can take place only after neutralization of the sulfuric acid with sodium carbonate.
U.S. Pat. No. 2,842,562 also describes a process utilizing a reduced quantity of sulfuric acid. The ring closure (cyclization) of OBB acid takes place at 260.degree. C. in the presence of a third solvent such as trichlorobenzene, with the water formed during the reaction being eliminated by distillation in the form of an azeotropic mixture with the third solvent. The use of the latter solvent complicates the equipment and is uneconomical since the anthraquinone must be recovered by separation from the solvent by steam distillation.
U.S. Pat. No. 2,174,118 proposes hydrofluoric acid as a cyclization catalyst for OBB acid. The use of such a reactant involves major drawbacks due to its very nature; namely, corrosion by the water/hydrofluoric acid combination formed during the course of the operation, difficult recovery of the hydrofluoric acid by dehydration of this same combination, and finally the necessity of operating the ring closure of the OBB acid under pressure.
U.S. Pat. No. 4,304,727 describes a process in which a perfluorinated resin in suspension in an inert organic solvent is used as a cyclization catalyst. Although the recovery of the catalyst is thus facilitated, the OBB acid conversion and the anthraquinone yield are low, for example, equal respectively to 60% and 78%. Additionally, it is necessary to proceed with the separation of the organic solvent from the anthraquinone.
The Japanese Patent Application No. 49.6240/74 recommends cyclizing the OBB acid by heating at 360.degree. C. in the presence of activated clay. This method presents drawbacks rendering it commercially unfeasible due to the necessity of operating in a vacuum, slow ring closure rate, necessity of an intimate mixture of the OBB acid and of the activated clay, and a low practical yield following the absorption by the activated clay of nearly one quarter of the anthraquinone formed. The recovery of the anthraquinone thus absorbed would require costly extraction operations from the clay with an organic solvent and then evaporation of the solvent.
French Utility Certificate No. 76.18956, published under No. 2,314,913, describes the cyclization of OBB acid in the presence of oxygenated compounds of aluminum and silicon, preferably by heating the OBB acid with aluminum silicate in powder form. When the process is conducted in suspension in an organic solvent, the elimination of the solvent and then of the catalyst is complicated and costly whether it is carried out in a fixed bed or in a fluidized bed. In the first case one risks a rapid clogging of the catalyst, while in the second case one risks coming up against a delicate separation of the fine particles of catalyst from the anthraquinone. The best yields of cyclization are also achieved when the latter process is carried out in a vacuum. | {
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The present invention relates to small molecule inhibitors of ERG oncoprotein and the use of such compounds as candidate therapeutics for treating ERG positive cancers, including prostate cancer (CaP). CaP is the most frequently diagnosed non-skin malignancy and second leading cause of cancer related deaths among men in the western countries. While early detected CaP due to PSA screening is managed effectively by surgery or radiation, a significant subset of CaP patients (20% to 40%) experience disease recurrence after definitive treatment and will require hormone ablation therapy. Despite initial response to therapy, metastatic CaP tumors eventually become refractory to hormone ablation therapy. For this subset of patients, namely, those having metastatic hormone refractory cancer there is no effective cure.
The ERG proto-oncogene belongs to a large family of ETS transcription factors that are both positive and negative regulators of gene expression (Watson et al., 2010). These transcription factors are downstream effectors of the mitogenic signal transduction pathways involved in cell proliferation, cell differentiation, development, transformation, apoptosis, and immune regulation (Watson et al., 2010; Sreenath et al., 2011). The ERG gene is the most prevalent and validated genomic alteration in prostate cancer. Recurrent TMPRSS2-ERG gene fusions are present in nearly half of all CaP patients in western countries. This gene fusion results in male hormone dependent and tumor cell specific expression of a truncated ERG protein (deletion of 32 amino terminal residues). ERG alterations and the overexpression of ERG protein, therefore, are implicated in the development and progression of CaP.
ERG expression in CaP is AR dependent. While there are a number of androgen receptor (AR) signaling inhibitors already being used as therapeutics for treating CaP, the present inventors were not previously aware of compounds that can selectively inhibit ERG expression. Accordingly, the invention describes small organic molecules that selectively inhibit ERG expression. | {
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Field of the Invention
The present invention relates to a display device and an image rendering method thereof in consideration of a saturation of a text image.
Discussion of the Related Art
Flat panel display devices such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a field emission display (FED) and a plasma display panel (PDP) are known.
A rendering algorithm converts data of an input image into data suitable for the pixel arrangement and structure of a display panel when the resolution of the input image differs from the physical resolution of the display panel. Such a rendering algorithm is applied to display devices.
When the resolution of an input image is different from the resolution of the display device, the quality of an image reproduced by the display device may deteriorate. It may not be difficult to process the input image into a high resolution image without loss of picture quality. However, when the resolution of the input image is converted into a lower resolution image matching the physical resolution of the display device, and the input image is reproduced with the converted resolution through the display device, a data distortion or loss may occur and thus, the picture quality may deteriorate.
Particularly, when a text in the input image is reproduced through a display device having a lower resolution than the input image, text legibility may deteriorate due to an omission or distortion of the data constituting the text. Various rendering algorithms have been proposed in order to enhance text legibility when the resolution of the display device is lower than that of the input image. The applicant proposed a rendering algorithm for improving text legibility in consideration of a difference between neighboring pieces of data when the resolution of a display device is lower than that of an input image (Korea Patent Application 10-2013-0139770 filed on 2013 Nov. 18).
When a text data is converted using conventional rendering algorithms, the legibility of the text data may deteriorate. Particularly, conventional rendering algorithms typically do not consider the saturation of text, focusing on an achromatic text data. Accordingly, the legibility of chromatic data may further deteriorate when conventional rendering algorithms are applied. | {
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The subject of the present invention is a process for obtaining an aged or faded effect on garments made of protein fibres, such as wool, cashmere and silk, and the product that can be obtained using said process. | {
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1. Field of the Invention
The present invention relates to a server apparatus having a function of loading a new file into a main memory and changing over from an old module to a new module.
2. Description of the Related Art
A server or the like changes over from an old file to a new file for an upgrade, addition of a new module, or the like. FIGS. 11 to 17 are diagrams representing a conventional method of changing over to a new file. As shown in FIGS. 11 to 17, servers 2#0 and 2#1 have a duplexed configuration to replace files. The server 2#0 is an operational system and the server 2#1 is a standby system, for example. In the server 2#i, a plurality of applications (modules) 16#iA00, 16#iB10, 16#iC30, . . . operate on a basic Operating System (OS) 4#i. Messages are communicated between the applications 16#iA00. . . and another node 3 via the basic OS 4#i. A conventional file update method is as follows.
In response to each new operation instruction, a message event is notified in a form of a maintenance command to the server 2#i (i=0, 1), and operation is performed by software of the server 2#i (i=0, 1) receiving the notification. In this case, suppose that the applications B10 and C30 are files to be updated to applications B80 and C90.
(1) Loading of New File
As shown in FIG. 11, new system files for an upgrade, for example application programs B80 and C90 for providing service are transferred from an external medium such as a Digital Audio Tape (DAT) or the like or a remote terminal onto disk devices 10#i (i=0, 1) of all the servers 2#i (i=0, 1) that are to update files, so that new files 12#i are created.
(2) Setting of File Update State
In order to regulate processing that may interfere with update operation, a system state retained on the software is changed from “normal” to “file update.”
(3) Booting of New File
As shown in FIG. 12, the standby server 2#1 is separated from the duplexed state, and stopped. A reboot program 14#1 is executed to load the new files into a memory. After the reboot, the application programs B80 and C90 stored as the new files 12#1 and a necessary application program A00 that is not to be updated are LM-loaded from the disk 10#1 onto the memory, whereby processes 16#1B80, 16#1C90, and 16#1A00 are generated. The server 2#1 is brought into a standby state. As shown in FIG. 13, the server 2#1 starts operation of the processes 16#1A00, 16#1B80, and 16#1C90, and is brought into a temporary operational state.
(4) Change to New File
As shown in FIG. 14, in order to change from the old files to the new files, the standby server 2#1 is set as an operational server, and the operational server 2#0 is set as a standby server and is stopped.
(5) Establishment of New File
As shown in FIG. 15, to ensure operation of the new file 4#1 of the server 2#1, the system state is monitored for a certain time. Thereafter, in order to change the old file environment of the server 2#0 to a new file environment, the server 2#0 is rebooted by a reboot program 14#0. After the reboot, the application programs B80 and C90 stored as the new files 12#0 and the necessary application program A00 that is not to be updated are LM-loaded from the disk 10#0 onto a memory, whereby processes 16#0B80, 16#0C90, and 16#0A00 are generated. As shown in FIG. 16, the server 2#0 starts operation of the processes 16#0B80, 16#0C90, and 16#0A00 and is brought into a temporary operational state. As shown in FIG. 17, after the operation of the server 2#0 is monitored for a certain time, the server 2#0 is brought into a standby state.
Prior art literature includes the following Patent Literature 1.
Patent Literature 1 discloses a technique for changing over from an active server to a reserve server without changing setting in a client computer.
Patent Literature 1 Japanese Patent Laid-Open No. Hei 10-23074
However, the conventional file update method has the following problems.
(1) When of the plurality of application load modules A00, B10, and C30, the module A00 is not changed and the modules B10 and C30 are changed to add service functions (B10 is changed to B80, and C30 is changed to C90), because a new LM is also created for the module (A00) not capturing the IF and modules are loaded after a reboot, replacement of the files including the old module (A00) needs to be performed. That is, even when only the modules B80 and C90 are necessary, all the modules to be substituted including not only the necessary modules B80 and C90 but also the unnecessary module A00 need to be loaded.
(2) As a condition for performing a file update, the duplexed server configuration is essential. This presents a problem in that investment cost and maintenance cost are increased because of the duplexed configuration.
(3) Changeover from an old file to a new file involves switchover between the servers of the duplexed configuration, thus causing a service interruption time. Also, there is a risk of not being able to change to the new file because of hardware abnormality.
Patent Literature 1 only discloses changeover between an active server and a reserve server in a duplexed configuration and is therefore not able to solve the above problem in the duplexed configuration. | {
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The present invention relates to a combination of a battery and a plug.
Batteries, especially lead storage batteries, invariably produce gases because of the underlying electrochemical processes during discharge and charging. The closure plugs of the cells therefore have holes through which gas exchange can occur. The ordinary plugs have a disadvantage in that they do not seal the cells completely liquid-tight, which can lead under extreme operating conditions or accidents and emergencies to leakage of very aggressive and highly corrosive electrolyte solutions, like sulfuric acid, and therefore to serious disadvantages and hazards.
German Utility Models DE-U 91 04 291 and DE-U 93 12 173 describe closure plugs for a lead storage battery in which a microporous frit or a microporous element is mounted in front of a pressure relief valve in the gas outlet direction. A disadvantage during the use of microporous elements is that the aerosols and especially sulfuric acid can clog or seal the pores of the microporous element because it creep into these. Gas permeability is extremely reduced by this and the storage battery is no longer safe.
Another disadvantage is that these elements are not liquid-repellent. For this purpose German Patent publication DE-OS 38 05 570 describes a porous inorganic substance in which the surface of the pores is coated with an internal film of silane or titanium adhesive and an external film of fluorocarbon resin. Such elements can only be produced with difficulty and are therefore very expensive.
U.S. Pat. No. 4,636,446 (LEE) discloses a stopper for a storage battery having a porous plastic body made of a spongy plastic and a spiral-shaped body provided with notches at both ends. The porous plastic body has numerous pores and is only permeable to gas. However the spongy plastic body is able to absorb water and is therefore permeable for liquids. Furthermore, the aerosols of the electrolyte creep into the pores of the spongy plastic body and block and close these pores.
French Patent FR-B-1,543,874 teaches a valve comprising a fibrous diaphragm made of highly hydrophobic fiber and an intercepting plate. This construction is not resistant to the electrolyte and aerosols of the electrolyte are able to creep into the diaphragm and block and close these pores.
The object of the present invention is therefore to improve the durability of a plug for a battery that is liquid impermeable and gas permeable.
The novel combination of a battery and a plug of the present invention is designated to solve the above discussed problems and provide significant advantages over the plugs of the prior art, as described in more detail herein.
The present invention is directed to a combination of a battery and a plug. The plug is situated in an opening of the battery and has a liquid impermeable but gas permeable membrane, being made of expanded microporous polytetrafluoroethylene (ePTFE), and an aerosol separator. The exchange of gas between the gas space and the outside of the battery takes place through the liquid impermeable but gas permeable membrane and the aerosol separator.
A plug according to the invention therefore includes an ePTFE-membrane that permits gas exchange between the gas space inside the battery and its surroundings and an aerosol separator, which separates electrolyte vapors and aerosols entrained by the electrolysis gases before they can reach the membrane. This arrangement achieves a situation in which the battery cell is degassed without the membrane being wetted by electrolyte aerosols, in which case a reduction in gas exchange would occur. Further, the novel combination of a battery and a plug ensure that the battery is protected from leakage of electrolyte in any position of the battery, because the ePTFE membrane is impermeable to liquids, especially to electrolytes like sulphuric acid. In one embodiment the membrane contains an oleophobic material. Preferably the membrane is laminated to at least one layer consisting of a support material. The support material protects and supports the membrane against mechanical loadings.
In a further embodiment the membrane has a pore size of at most 1 xcexcm. a porosity of at least 50% and a dried thickness most 5 xcexcm. These parameters ensure the high and effective gas permeability of the membrane over the lifetime of the plug. The aerosol separator is chosen from one of the following group of separators: a fiber absorber, a centrifugal separator, a cascade separator, an inertial separator, a combination of at least two of the aforementioned. Preferably the aerosol separator is a combination of an inertial separator, a centrifugal separator and a cascade separator. This construction of an aerosol separator ensures the effective separation of the aerosols in the electrolysis gas. The electrolysis gas without aerosols can reach the membrane. | {
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1. Field of Invention
The present invention relates to a two-step thermal process for recycling scrap tires and waste or other oils with emphasis on the production of valuable products including overhead light oil, and gas and a carbonaceous material useful as a modifier for bituminous binders and Portland concrete.
2. Background
Upwards of 280 million tires are accumulated annually in the United States and about 65 percent are added to stockpiles, landfills or disposed of by other means. The Environmental Protection Agency estimates there are more than two billion discarded tires in this country. Accidental fires at storage sites have been a continuing environmental problem.
Waste motor and industrial oils also contribute to a hazardous waste disposal problem. An estimated 400 million gallons of waste motor oils are illegally dumped in landfills each year. Reprocessing waste oils to produce "new" recycled oils for the motoring public or industrial uses is not economically feasible because collection expenses and refining costs including waste disposal of residual oil sludge are too high and there is a lack of consumer acceptance for reprocessed oils.
A current scrap tire use is the making of crumb rubber modifier for asphalt cements and this consumes upwards of 1.8 million tires per year; however, in comparison to the supply, this is a minor use. Yet the concept of asphalt modification is a useful field to utilize the products from scrap or waste tire reprocessing.
Since more than 90 percent of the paved roads in the United States utilize asphalt, the potential for asphalt modifiers is great. Asphaltic concrete pavement failures traditionally have reasons associated with rutting, moisture-induced induced damage and embrittlement. Many asphalt modifiers have been proposed. See the classic Barth's Asphalt, Gordon and Breach, N.Y. 1962, for a discussion of a wide range of tests concerning modifiers. In particular carbon black modifiers have shown considerable success in reducing rutting and low temperature cracking difficulties. For more than a half a century the annual series Asphalt Paving Technology, Viking Press, Eden Prairie, Minn., summarizes much information on using various asphalt modifiers.
Asphalt when used for its intended purposes often suffers from premature failure due to factors such as aging, embrittlement, or loss of adhesion or cohesion properties. Much development has occurred to improve its performance and rheological properties. However in such instances, asphalt road life is still much less than desired. In recent years numerous advantages have been found for incorporating some form of rubber modifier into asphalt. The rubber gives the asphalt improved elastic behavior, increases its ductility, reduces is susceptibility to temperature changes, and in addition, can improve the surface life of roads.
In order to improve asphalt durability, many rubber-like polymers; such as neoprene, GRS rubbers, latex, nitrile rubber, butyl rubber, natural rubber, and others; have been blended, usually at a composition of a few percent, with asphalt in a conventionally mixing operation; see Barth referenced above.
Direct combustion processes use an estimated 25 million tires annually. Although tires have a high heating value of 15,000 BTU/lb, their economic value as a fuel diminishes because tires contain about 2.5 wt % sulfur. Facilities that use scrap tires as a supplemental fuel source often blend them with coal to keep sulfur pollutants in the stack gas within tolerable levels. Higher levels of sulfur pollutants would require stack gas clean-up which jeopardizes the economics of using tires as a fuel supplement. Further problems arise in combusting waste tires due to their fiber and wire, usually steel, content. Particularly shredded waste tires must overcome this fiber and wire tangling problem with processing machinery.
Pyrolysis, which normally implies thermal degradation at 900.degree.-1400.degree. F. in an inert atmosphere, has been tested both in the laboratory and in pilot-scale equipment to produce either hydrocarbon gases or oils plus a coke-like residue of carbon black. Direct pyrolysis of tires has a disadvantage in that gaseous products generally contain moderate levels of hydrogen sulfide and liquid products contain substantial amounts of chlorinated materials. The presence of chlorinated materials in the oil reduces its value as a refinery feed stock for hydrogenation and other processes. Even low levels of chlorinated materials in feed oils result in process corrosion problems in vessels and piping.
Although many forms of distress in asphaltic and concrete pavements have been identified and solutions sought, problems continue to exist either because the solutions are inadequate or because new variables causing distress manage to stay ahead of the research. Increased traffic and vehicular loads coupled with increased tire pressures have greatly contributed to pavement distress, reduced safety, and increased maintenance costs. These problems associated with permanent distortions, commonly referred to as rutting, in bituminous pavements are further compounded by the effects of moisture-induced damage or moisture sensitivity. Moisture damage, embrittlement, crack formation with adhesion loss between the bituminous binder and the mineral aggregates and rut formation are four major causes of pavement failures. A solution to any one of these problems would have a profound effect in increasing the service life of our roadways and simultaneously provide added benefits to the motoring public.
Surface areas covered with Portland concrete also experience similar forms of distress and high maintenance costs. Crack formation during drying and/or curing modes coupled with load induced failures contribute significantly to maintenance costs. Air encapsulation in Portland concrete increases porosity and permeability of the concrete which allows penetration of salts and water into the concrete structure thereby facilitating corrosion of the steel reinforcing structure. Portland concrete adheres poorly to oily metallic surfaces such as those found in sealing of oil wells. In frigid climates the natural deicing characteristics are inadequate simply because concrete is a poor absorber of solar energy.
Potential United States patents covering the above mentioned concepts include:
______________________________________ U.S. Pat. No. Inventor Year ______________________________________ 5,095,040 Ledford 1992 5,084,141 Holland 1992 5,070,109 Ulick et al 1991 5,060,584 Sowards et al 1991 5,041,209 Cha-1 et al 1991 4,983,782 Mertz et al 1991 4,983,278 Cha-2 et al 1991 4,960,440 Betz 1990 4,895,083 McDilda 1990 4,894,140 Schon 1990 4,867,755 Majid et al 1989 4,806,232 Schmidt 1989 4,787,321 Schnellbacher et al 1988 4,746,406 Timmann 1988 4,686,008 Gibson 1987 4,686,007 Lyakhevich et al 1987 4,647,443 Apffel 1987 4,560,414 Kikegawa et al 1985 4,515,659 Wingfield et al 1985 4,383,151 Audibert et al 1983 4,332,932 Harada et al 1982 4,25O,158 Solbakken et al 1981 4,211,576 Yan 1980 4,166,049 Huff 1979 4,153,514 Garrett et al 1979 4,123,332 Rotter 1978 4,030,984 Chambers 1977 3,978,199 Maruhnic et al 1976 3,915,581 Copp 1975 3,907,582 Walter 1975 3,875,077 Sanga 1975 3,873,474 Ficker 1975 866,758 Wheeler 1907 ______________________________________
Referring to the above list, Ledford disclosed rotary kiln processing of shredded tires with 1000.degree. F. inlet and 800.degree. F. outlet using indirect gas heating.
Holland disclosed waste tire processing by preheating and then microwaving. Microwave energy used to break carbon-carbon bond.
Ulick et al disclosed processing rubber tires using aromatic hydrocarbon oil at up to 600.degree. F. Products obtained were a grease-like and putty-like material which were added to asphalt to improve low-temperature flow properties.
Sowards et al disclosed combusting shredded tires with limestone to control SO.sub.2 emissions.
Cha-1 et al disclosed processing heavy oil using inclined screw pyrolysis reactors and obtaining light, middle and heavy distillates and asphalt binder. Limestone added to remove sulfur containing components from gases.
Mertz et al disclosed waste treatment of old tires with basic addition, such as lime, to trap acidic gases including SO.sub.2, NO.sub.2, and HCl.
Cha-2 et al disclosed processing oil shale, tar sand, waste motor oil, or waste tires for pyrolysis products with recycling of selected distillates. Pyrolysis temperature up to 800.degree. F. Scrap tire process used inclined screw pyrolysis reactor and waste motor oil with magnetic separation of scrap metals. Screw reactors were symmetrically housed. Carbon black obtained used for asphalt modifier.
Betz disclosed producing pyrolysis gas from used tires with a fluidized bed. Sulfur cleanup was employed by adding a basic binder, such as calcium carbonate, hydrated lime, calcium oxide, magnesium carbonate, magnesium oxide, magnesium hydroxide, dolomite, sodium carbonate or sodium hydroxide.
McDilda disclosed combustion of tires and recovery of products from the gases.
Schon disclosed processing waste oil by itself.
Majid et al disclosed reduction of sulfur emission during combustion by the addition of limestone, lime or hydrated lime.
Schmidt disclosed desulfurization of H.sub.2 S from used oil pyrolysis with basic additive and metal to catalyze H.sub.2 S removal.
Schnellbacher et al disclosed apparatus for chopped old tire combustion using ash grate with rotating fingers and operating temperature of 150.degree.-700.degree. F.
Timmann disclosed a pyrolyzing system for tires to produce increased C-4 components by condensing light oil fraction at near 32.degree. F.
Gibson disclosed apparatus for pyrolysis of shredded tires using partial flight screw with oil jet spray and temperature range employed was 1000.degree.-1400.degree. F.
Lyakhevich et al disclosed shredded tire processing at 150.degree.-500.degree. C. with solvent injection through nozzles.
Apffel disclosed carbon black from tires, no oil added, obtained using preheated steam and pyrolysis by hot gas at 2000.degree. F.
Kikegawa et al disclosed asphalt modifier of Trinidad Epure with pulverulent solid, such as lime or gilsonite, for high temperature performance.
Wingfield et al disclosed catalyze pyrolyric conversion of waste rubber with basis salt, such as sodium carbonate, producing increased amount of C.sub.1 -C.sub.4 olefinic materials including isobutylene.
Audibert et al disclosed heating whole tires in oven while spraying with hot heavy oil that was recycled. Temperature of operation was 350.degree.-500.degree. C. with 10:1 ratio of oil to whole tires.
Harada et al disclosed screw extruder for melted waste rubber at 400.degree.-500.degree. C. using no added oil.
Solbakken et al disclosed fragmented used tires pyrolyzed under vacuum with oxygen-limited. Main product was carbon black with tar refluxed. Reactor temperature range was 750.degree.-1800.degree. F. with pressure 1-20 psia.
Yan disclosed dissolving scrap tire rubber in thermally stable highly aromatic solvent with heating at 350.degree.-850.degree. F. until homogeneous and using as asphalt modifier.
Huff disclosed rubberized asphalt made from reclaimed rubber from scrap tires containing critically 30-40% second acidaffins.
Garrett et al disclosed process using shredded waste tires heated to 300.degree.-2000.degree. F. with desulfurization by adding solid sulfur acceptor, such as lime or iron oxide.
Rotter disclosed direct pyrolysis of shredded tires at 400.degree.-900.degree. C. by indirect oxygen-free combustion gas using equipment with staggered paddle-like impeller.
Chambers disclosed using hot gas at 600.degree. F. for melting of whole scrap tires with a wet scrubber for gas cleanup. Carbon black produced at 1100.degree. F. under vacuum conditions.
Maruhnic et al disclosed carbon black production from tires using aromatic solvent at 500.degree.-700.degree. F., 25-100 psig, and filter collection.
Copp disclosed carbon black reinforced polymer used as modifier for asphalt paving.
Walter disclosed asphalt modification with additives of lime and residue from refuse incinerator.
Sanga disclosed waste tire production for activated charcoal using limestone to produce CO atmosphere for product conversion of carbon to activated charcoal. Temperature of decomposition was 400.degree.-800.degree. C.
Ficker disclosed comminuted scrap rubber through heated feed screws at 140.degree.-300.degree. C. using differential gearing with interleaved helical threads; one with twice the pitch.
Wheeler disclosed reclaiming scrap rubber with superheated steam at 600.degree. F.
Foreign patents of interest include Lengd, SU 0644802, 1979, who disclosed making asphalt with the addition of limestone powder and shale processing residue. Yarosl, SU 979125, 1982, disclosed using zinc oxide with rubber to improve solubility in organic solvents.
Asphalt is a viscoelastic material which means it exhibits both viscous and elastic behavior and displays a time dependent relation between an applied stress and the resultant strain. Thus when testing asphalt it is common to refer to the rheological properties as measured by dynamic testing procedures. Rheological testing machines subject a test cylinder of asphalt to a periodic or dynamic loading pattern involving a sinusoidal input on one end and measure the resulting response on the opposite end which now is out of phase with the input. Thus the shear modulus, G*, has a real and an imaginary component, G' and G". The rheological results are usually expressed in terms of the following: EQU Loss tangent=tan (delta)=G"/G' EQU Complex shear modulus=.vertline.*.vertline.=[(G').sup.2 +(G").sup.2 ].sup.1/2 EQU Dynamic viscosity=eta*=.vertline.G*.vertline./omega
where delta is the phase angle and omega the applied strain frequency. See Ferry, Viscoelastic Properties of Polymers, John Wiley, N.Y. 1961; or Goodrich, "Asphalt and Polymer Modified Asphalt Properties Related to the Performance of Asphalt Concrete Mixes," Asphalt Paving Technology 1988, 57, pp 116-126, Viking Press, Eden Prairie, Minn., 1988. Properties of asphalt binders with and without modifiers generally are expressed in these rheological terms. | {
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1. Field of the Invention
The present invention relates to bag filling apparatus for filling loose or particulate material into bags.
2. Prior Art
The filling of bags has long been done with a variety of devices, but problems in packing material that doesn't flow, such as loose fill insulation that is formed by grinding or pulverizing cellulose fiber still exist. The present device simplifies the job and makes sure that the bags are filled with the desired amount of density. | {
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In an electric vehicle (EV), a hybrid electric vehicle (HEV), and so on, there have been various proposals for a shield structure used for connection between apparatuses (such as a motor and an inverter) housed in a metal case (for example, see Patent Literature 1).
The shield structure is provided with a shielded electric wire in which a plurality of electric wires are collectively covered with a braided wire, and terminals connected to both ends of the shielded electric wire are mounted to a connector.
Each connector is provided with an electroconductive metal shell attached to a case housing an apparatus therein and covering an internal conductor (such as a terminal), and an end of the braided wire is connected to each metal shell. According to this constitution, the braided wire is electrically connected to the case, and radiation of electromagnetic waves can be prevented. | {
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1. Field of the Invention
This invention generally relates to a flying saucer toy having an aerodynamic characteristic enabling it to spin and to travel considerable distances when thrown into the air and, more particularly, to such an aerial toy having an on-board signaling device which is only reliably actuated during flight.
2. Description of Related Art
U.S. Pat. No. 3,359,678 discloses a flying saucer toy for toss games and the like. To add interest to the use of such a flying toy, battery-powered lights have been mounted thereon, usually at the periphery thereof, as disclosed, for example, in U.S. Pat. Nos. 4,435,917 or 4,563,160. To prevent rapid battery drain, a single centrifugally-actuated switch is employed, as suggested by U.S. Pat. No. 3,798,834, for actuating a battery-powered light or buzzer during flight.
Experience has shown, however, that the use of a single centrifugally-actuated switch to actuate a light or buzzer on board the aerial toy is not altogether desirable. Such a centrifugal switch typically has a movable switch contact which is spring-biased away from the light or buzzer. The spring bias is relatively weak so that it may readily be overcome by centrifugal force generated during flight. However, over time, and particularly after the aerial toy has been subjected to repeated shocks as a result of impacting against obstacles in the flight path over extended use, the spring bias becomes even weaker. As a result, sometimes the force of gravity alone is sufficient to move the movable switch contact, thereby actuating the light or buzzer when the toy is not in flight but is merely being held or stored in a vertical plane. This leads to rapid battery drain and frequent battery replacement. | {
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1. Field of the Invention
This invention resides in the field of fluid dispensers and more particularly relates to a medical treatment system where medicated and non-medicated fluids, lotions, gels and the like are delivered through a ring worn on a therapist's finger for application on a patient.
2. Description of the Prior Art
Traditionally, clinicians, physical therapists and medical personnel have applied lotion to a patient by squeezing an appropriate amount from a container onto their hand and then have applied such lotion manually directly to the patient's skin. Lotion dispensing containers, many of which work by compressing the container to squeeze out the lotion, are known in the prior art. Examples include U.S. Pat. No. 5,476,194 to Hippely et al which describes a flexible dispenser which can be worn around a person's neck; and U.S. Pat. No. 4,657,159 to Grant which discloses a meniscus-shaped container. One disadvantage of these types of containers is that a therapist must go back and forth between obtaining lotion from the container and applying it to the patient, wasting valuable time. There is also the potential for contamination if the therapist's hands carry germs from the patient to the container or if excess lotion originally removed from the container is replaced back in the container when not needed.
Other types of lotion-dispensing devices often include a container housing the lotion with some type of applicator at the end, where the applicator contacts a patient's skin after becoming saturated with lotion. Examples include U.S. Pat. No. 5,322,382 to Hull et al and U.S. Pat. No. 4,889,441 to Tice. With these types of devices the therapist has difficulty controlling the delivery of lotion to the patient's skin and must stop the therapy, such as a massage, to apply the lotion.
Hand-held spray devices often appear in children's toys. U.S. Pat. No. 5,303,847 to Cottone discloses a water toy worn on a user's hand which includes a targeting finger sheath having a discharge nozzle for spraying water. An actuating finger sheath worn on another finger controls operation of an electric motor and water pump which pumps water contained in a housing through a pipe and out the nozzle on the targeting finger sheath. U.S. Pat. No. 4,037,790 describes a water glove toy which expels water from an area near the wrist by pressing on a compressible bulb at the palm portion of the glove. | {
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With the vast array of video editing tools available, many people can readily edit existing video and incorporate special effects to customize videos and to produce stylish graphics. These videos may later be published for others to view. In many cases, however, an individual may want a more professional look before sharing the video with friends and family. Use of professional video editing services may not be a feasible alternative in many instances due to cost. Furthermore, traditional off-the-shelf video editing solutions are proving to fall short in meeting the needs of consumers. One common problem with traditional video editing solutions is the amount of time and degree of complexity involved in the overall editing process. Another perceived problem associated with conventional methods is that the original video is typically modified during the editing process. This can present a problem if the video content is under copyright protection. | {
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1. Field of the Invention
The present invention relates to a resin composition for ink supply tubes and also relates to an ink supply tube.
2. Description of the Related Art
Conventional ink jet recording apparatuses make records on recording media in such a manner that inks are ejected from ink jet recording heads. In such an ink jet recording apparatus, a carriage equipped with an ink jet recording head is moved over a recording medium in a main scanning direction and ink is ejected from the ink jet recording head while moving to perform recording. After a main scan is performed once, the recording medium is moved by a certain amount in an auxiliary scanning direction and the carriage is moved in the main scanning direction again to perform recording. A desired pattern can be recorded on the recording medium by repeating this operation.
A type of ink supply unit for use in the ink jet recording apparatus is equipped with a replaceable tank (ink tank), filled with ink, separate from the carriage. In the ink jet recording apparatus, the ink tank is connected to the ink jet recording head, which is aboard the carriage, through an ink supply tube placed therebetween such that ink is supplied to the ink jet recording head. This type is suitable for the purpose of using a relatively large amount of ink because the volume of the ink tank can be readily increased.
When the ink jet recording apparatus is used for recording, the ink supply tube, which connects the ink tank to the ink jet recording head, is pulled or twisted due to the reciprocating motion of the carriage, which equipped with the ink jet recording head, and therefore is increased in flexural rigidity. If the ink supply tube has high hardness, fatigue failure may possibly occur therein. Therefore, the ink supply tube needs to have flexibility enough to cope with reciprocation. In particular, the ink supply tube needs to cope with reciprocation with a smaller curvature and needs to have higher flexibility because of the recent downsizing of ink jet printers.
If moisture evaporates from ink present in the ink supply tube to leak out of the ink supply tube, the viscosity of the ink therein will increase. This may cause serious problems such as improper ink ejection and a reduction in print quality due to the change in composition of the ink. In addition, if gases such as air permeate through the ink supply tube, the gases will dissolve in the ink in the ink supply tube to cause a reduction in the degree of deaeration of the ink or the creation and growth of bubbles in the ink. This may possibly cause improper ink ejection and a reduction in print quality. Therefore, the ink supply tube needs to have high moisture barrier performance and air barrier performance.
Japanese Patent Laid-Open No. 9-300652 discloses an ink supply tube for ink jet recording. This ink supply tube has a layered structure consisting of an inner layer in contact with ink, an outer layer in contact with air, and an intermediate layer made of a material with low gas permeability, the inner and outer layers being made of a material having ink resistance, low permeability, and low rigidity. In particular, the inner and outer layers are made of polyethylene and the intermediate layer is made of an ethylene-vinyl alcohol copolymer or polyvinylidene chloride.
Techniques for using highly flexible thermoplastic elastomers to prepare ink supply tubes for ink jet recording are being investigated. Such thermoplastic elastomers include olefinic thermoplastic elastomers, urethane thermoplastic elastomers, ester thermoplastic elastomers, styrenic thermoplastic elastomers, and polyvinyl chloride thermoplastic elastomers. In particular, the styrenic thermoplastic elastomers have excellent flexibility and rubber elasticity. Examples of the styrenic thermoplastic elastomers include styrene-butadiene-styrene (SBS) block copolymers, styrene-isoprene-styrene (SIS) block copolymers, styrene-ethylene-butylene-styrene (SEBS) block copolymers, and styrene-ethylene-propylene-styrene (SEPS) block copolymers. In recent years, styrene-isobutylene-styrene (SIBS) block copolymers have been developed.
Japanese Patent Laid-Open No. 2005-305878 discloses a resin composition, containing a thermoplastic elastomer, for ink jet recording. In particular, the resin composition contains a styrene-isobutylene-styrene (SIBS) block copolymer, a polyolefin, and liquid polybutene and has excellent gas barrier performance, excellent moisture barrier performance, and good flexibility. | {
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There are many commercial applications in which large numbers of digital images are manipulated. For example, in the emerging practice of digital photofinishing, vast numbers of film-originated images are digitized, manipulated and enhanced, and then suitably printed on photographic or inkjet paper. With the advent of digital image processing, and more recently, image understanding, it has become possible to incorporate many new kinds of value-added image enhancements. Examples include selective enhancement (e.g., sharpening, exposure compensation, noise reduction, etc.), and various kinds of image restorations (e.g., red-eye correction).
In these types of automated image enhancement scenarios, one basic piece of semantic image understanding consists of knowledge of image orientation—that is, which of the four possible image orientations represents “up” in the original scene. Film and digital cameras can capture images while being held in the nominally expected landscape orientation, or held sideways. Furthermore, in film cameras, the film may be wound left-to-right or right-to-left. Because of these freedoms, the true orientation of the images will in general not be known a priori in many processing environments. Image orientation is important for many reasons. For example when a series of images are viewed on a monitor or television set, it is aggravating if some of the images are displayed upside-down or sideways. Additionally, it is now a common practice to produce an index print showing thumbnail versions of the images in a photofinishing order. It is quite desirable that all images in the index print be printed right side up, even when the photographer rotated the camera prior to image capture. One way to accomplish such a feat is to analyze the content of the scene semantically to determine the correct image orientation. Similar needs exist for automatic albuming, which sorts images into album pages. Clearly, it is desirable to have all the pictures in their upright orientation when placed in the album.
Probably the most useful semantic indication of image orientation is the orientation of people in a scene. In most cases, when people appear in scenes, they are oriented such that their upward direction matches the image's true upward direction. Of course, there are exceptions to this statement, as for example when the subject is lying down, such as in a picture of a baby lying on a crib bed. However, examination of large databases of images captured by amateur photographers has shown that the vast majority of people are oriented up-right in images. This tendency is even stronger in images produced by professional photographers, i.e., portraits.
Another useful semantic indication of image orientation is sky. Sky appears frequently in outdoor pictures and usually at the top of these pictures. It is possible that due to picture composition, the majority of the sky region may be concentrated on the left or right side of a picture (but rarely the bottom of the picture) Therefore, it is not always reliable to state “the side of the picture in which sky area concentrates is the up-right side of the picture”.
Text and signs appear in many pictures, e.g., street scenes, shops, etc. In general, it is unlikely that signs and text are placed sideways or upside down, although mirror image or post-capture image manipulation may flip the text or signs. Detection and recognition of signs can be very useful for determining the correct image orientation, especially for documents that contain mostly text. In U.S. Pat. No. 6,151,423 issued Nov. 21, 2000, Melen disclosed a method for determining the correct orientation for a document scanned by an OCR system from the confidence factors associated with multiple character images identified in the document. Specifically, this method is applicable to a scanned page of alphanumeric characters having a plurality of alphanumeric characters. The method includes the following steps: receiving captured image data corresponding to a first orientation for a page, the first orientation corresponding to the orientation in which the page is provided to a scanner; identifying a first set of candidate character codes that correspond to characters from the page according to the first orientation; associating a confidence factor with each candidate character code from the first set of candidate character codes to produce a first set of confidence factors; producing a second set of candidate character codes that correspond to characters from the page according to a second orientation; associating a confidence factor with each candidate character code from the second set of candidate character codes to produce a second set of confidence factors; determining the number of confidence factor values in the first set of confidence factors that exceed a predetermined value; determining the number of confidence factor values in the second set of confidence factors that exceed the predetermined value; and determining that the correct page orientation is the first orientation when the number of confidence factors in the first set of confidence factors that exceeds the predetermined value is higher than the number of confidence factors in the second set of confidence factors that exceeds the predetermined value. This method was used to properly re-orient scanned documents which may not be properly oriented during scanning.
In addition to face, sky and text, other semantic objects can be identified to help decide image orientation. While semantic objects are useful for determining image orientation, they are not always present in an arbitrary image, such as a photograph. Therefore, their usefulness is limited. In addition, there can be violation of the assumption that the orientation of the semantic objects is the same as the orientation of the entire image. For example, while it is always true that the texture orientation is the same as a document composed of mostly text, it is possible that text may not be aligned with the upright direction of a photograph. Furthermore, automatic detectors of these semantic objects are not perfect and can have false positive detection (mistaking something else as the semantic object) as well as false negative detection (missing a true semantic object). Therefore, it is not reliable to rely only on semantic objects to decide the correct image orientation.
On the other hand, it is possible to recognize the correct image orientation without having to recognize any semantic object in the image. In U.S. Pat. No. 4,870,694 issued Sep. 26, 1989, Takeo teaches a method of determining the orientation of an image of a human body to determine whether the image is in the normal erect position or not. This method comprises the steps of obtaining image signals carrying the image information of the human body, obtaining the distributions of the image signal levels in the vertical direction and horizontal direction of the image, and comparing the pattern of the distribution in the vertical direction with that of the horizontal direction, whereby it is determined whether the image is in the normal position based on the comparison. This method is specifically designed for x-ray radiographs based on the characteristics of the human body in response to x-rays, as well as the fact that a fair amount of left-to-right symmetry exists in such radiographs, and a fair amount of dissimilarity exists in the vertical and horizontal directions. In addition, there is generally no background clutter in radiographs. In Comparison, clutter tends to confuse the orientation in photographs.
Vailaya et al., in “Automatic Image Orientation Detection”, Proceedings of International Conference on Image Processing, 1999, disclosed a method for automatic image orientation estimation using a learning-by-example framework. It was demonstrated that image orientation can be determined by examining the spatial lay-out, i.e., how colors and textures are distributed spatially across an image, at a fairly high accuracy, especially for stock photos shot by professional photographers who pay higher attention to image composition than average consumers. This learning by example approach performs well when the images fall into stereotypes, such as “sunset”, “desert”, “mountain”, “fields”, etc. Thousands of stereotype or prototype images are used to train a classifier which learns to recognize the upright orientation of prototype scenes. The drawback of this method is that it tends to perform poorly on consumer snapshot photos, which tend to have arbitrary scene content that does not fit the learned prototypes.
Depending on the application, prior probabilities for image orientation can vary greatly. Of course, in the absence of other information, the priors must be uniform (25%). However, in practice, the prior probability of each of the four possible orientations is not uniform. People tend to hold the camera in a fairly constant way. As a result, in general, the landscape images would mostly be properly oriented (upside-down is unlikely), and the task would be to identify and orient the portrait images. The priors in this case may be around 70%–14%–14%–2%. Thus, the accuracy of an automatic method would need to significantly exceed 70% to be useful.
It is also noteworthy that in U.S. Pat. No. 5,642,443 issued Jun. 24, 1997, Goodwin teaches how to determine the orientation of a set of recorded images. The recorded images are scanned. The scanning operation obtains information regarding at least one scene characteristic distributed asymmetrically in the separate recorded images. Probability estimates of orientation of each of the recorded images for which at least one scene characteristic is obtained are determined as a function of asymmetry in distribution of the scene characteristic. The probability of correct orientation for the set of recorded images is determined from high-probability estimates of orientation of each of the recorded images in the set. Note that Goodwin does not rely on high-probability estimates of the orientation for all images; the orientation of the whole set can be determined as long as there are enough high-probability estimates from individual images.
Semantic object-based methods suffer when selected semantic objects are not present or not detected correctly even if they are present. On the other hand, scene layout-based methods are in general not as reliable when a digital image does not fall into the types of scene layout learned in advance.
There is a need therefore for an improved method of determining the orientation of images. | {
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Electronic clocks with quartz-crystal oscillators are part of the state of art. Ordinarily, such clocks are powered by primary batteries. In the last few years, the power consumption of electronic time-keeping and display circuitry has decreased and it has become possible to power these clocks with electricity provided by solar cells. Wrist watches containing rechargeable batteries and solar cells for recharging are also known.
Electronic clocks with low-voltage high capacity capacitors have also been introduced on the market. The capacitors of such clocks are charged with solar cells positioned in the dial, and achieve a running-time power reserve of 50 hours. However, that power reserve appears insufficient for the winter season in the Federal Republic of Germany and in countries of similar geographic locations.
The purpose of the invention is to create a solar powered electronic clock with a high running-time power reserve to ensure proper time-keeping over periods of prolonged darkness. | {
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The present invention relates generally to high strength, low weight structures comprising an amorphous core or filler material surrounded and fused to a shell composed of resin-coated high strength composite filaments or fibers. More specifically, the present invention relates to a lightweight, high strength and stiff tennis racket having improved energy absorption characteristics, structural endurance and easily controlled mass distribution for specific applications.
There is presently a wide variety of tennis rackets available to today's tennis player. These tennis rackets are made from various different materials and are available in numerous different sizes, weights, and configurations.
One of the more popular tennis frames developed recently is based on the use of resin-coated composite filamentary materials such as graphite fiber, glass fiber, boron filaments, kevlar filaments or any combinations thereof. By far, the most popular composite racket is made from resin impregnated graphite fibers.
Graphite fiber composite materials were originally developed for aerospace applications in high performance aircraft and missile structures. Due to the inherent lightweight and high strength of graphite composites, they were also found especially well suited for use in sports equipment. As a result, graphite composites have been widely used in the production of lightweight, high strength and high performance tennis racket frames. When cured at elevated temperatures, the resin-coated graphite fibers form a high strength, rigid and lightweight structure which is particularly well suited for providing a high performance tennis racket.
Basically, tennis frames made from graphite composites include a tubular rigid composite frame structure or shell. The hollow core present in such a tubular frame structure is typically filled with a variety of core materials. The properties and configurations of both the rigid composite shell and core structure are important in providing a tennis racket with desired performance qualities. Graphite fibers of various different sizes impregnated with a wide variety of resin materials are commercially available. Many of these commercially available graphite composite materials have been used to provide entirely adequate rigid tubular tennis frame structures. With regard to the core structure, however, there has yet to be developed a core material or structure which has been found entirely adequate for use in the high performance graphite tennis rackets.
An optimum core structure should provide good energy absorption characteristics to reduce shock and vibration which otherwise would be present in a hollow tubular frame structure during ball impact. Further, the mass distribution of the core material throughout the tennis frame tubular structure should be easily varied. This variable mass distribution allows fine tuning or balancing of mass between the frame head and handle to enhance desired performance characteristics. The core structure should also be resistant to degradation and decomposition due to shock and vibration over long periods of racket use. In addition, it is desirable that the core material fuse or otherwise bond to the interior of the rigid composite shell to insure a solid vibration-free feel during racket use.
Another important property desirable in an optimum core material is the ability of the core material to expand of otherwise provide internal pressurization during molding of the graphite racket. Typical production of graphite composite/core tennis rackets involves surrounding the core with graphite fibers in specific orientations. The graphite fiber/core structure is then molded at elevated temperatures to provide the desired structural shape. The internal pressure for insuring that the rigid graphite shell is molded properly is typically and most conveniently provided by the core itself. The core material's ability to expand or otherwise generate internal pressure is therefore an important quality which is desirable in commercial processes for producing such graphite composite tennis rackets.
Foamable or intumescent resinous compositions have been utilized as suitable core materials. Foamable materials are desirable since they provide the necessary internal pressure during the molding operation. Typically, the resin compositions are mixed with various additives such as barium sulfate, chopped cork, glass, asbestos, fibers, mica flakes and the like. These additives are used for various reasons ranging from control of density within the core to low density fillers to produce a lighter weight racket. These resinous core compositions typically include epoxy or phenolic resins. The core characteristics range from stiff, hard and brittle compositions, to those compositions having consistencies of firm putty or molding clay. Although many of the core materials presently being used in graphite frames have been found adequate for their intended purpose, problems have been experienced with premature deterioration and crumbling of the core material resulting in loss thereof through stringing holes or other openings in the racket frame.
Although the core structures and materials presently being utilized in composite tennis frame structures are adequate for their intended purpose, none have been found entirely adequate in providing a core structure which optimizes all of the desirable core characteristics or qualities discussed above. It is therefore desirable to provide a core which not only provides internal pressure for molding the rigid composite shell but also allows covenient mass distribution throughout the tubular structure, enhanced absorption of racket shock and vibration along with increased resistance to core degradation or breakdown due to prolonged shock and vibration. | {
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Wide-area networking systems serviced by ATM (Asynchronous Transfer Mode) have multiple nodes that are interconnected by high-speed data links. Each network has a plurality of nodes, which may each contain switching devices that regulate data traffic to user equipment. User equipment may be connected to the nodes.
Each node has a controller device and switch, which facilitate the calls through the node. The controller has processing, memory, and other resources to interpret, forward, and process messages and initiate other messages as appropriate, while the switch ordinarily handles the physical routing of messages among nodes and user terminals.
In a redundant high-availability private network-to-network interface (“PNNI”) routing protocol implementation, a redundant pair of controllers is used in the case of controller failure. Thus, each node has two controllers, one primary and one secondary. In order to ensure proper functioning, it is desirable to perform maintenance and testing on the links. | {
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1. Field of the Invention
This invention pertains to lead locking devices and methods for locking onto a lead, and more particularly to lead locking devices and methods for locking onto and removing a lead from a patient's body, such as a pacemaker lead.
2. Description of Related Art
Various medical procedures attach wire-like devices to internal portions of a person's body, such as an electrical lead for a pacemaker or a catheter. Pacemaker leads are electrically conducting wires which run to an electrode that is attached to an inner wall of a person's heart. Pacemaker leads are typically a coil of wire enclosed in an outer cylindrical sheath of electrically insulating material. The coil of wire usually leaves a hollow space running down the center of the pacing lead (a "lumen").
Pacing leads are usually implanted with the intention that they will remain in the patient for several years. During such time, fibrous tissue grows over the electrode and portions of the lead. Pacing leads are often provided with additional barb-like structures or a corkscrew type of structure to encourage adhesion to the inner wall of the patient's heart.
Pacing leads sometimes fail or it is sometimes desirable to place an electrode at a different position from a previous position. It is then necessary to determine what should be done with the unused pacing leads. Both the removal of a pacing lead and leaving it in the patient entail associated risks. Leaving the pacing lead in the patient can increase the chances of infection, interfere with the additional pacing leads, or cause additional complications. On the other hand, removing pacing leads can cause severe, and possibly fatal, damage to the patient's heart.
Numerous devices have thus been developed that can be inserted into the lumen of a pacing lead and attach to the pacing lead close to the electrode in order to apply traction to the end of the lead close to the electrode. A series of patents to Goode et al (U.S. Pat. Nos. 4,943,289; 4,988,347; 5,011,482; 5,013,310; and 5,207,683) disclose various devices which attach to the pacing lead at a localized region close to the electrode. Peers-Trevarton (U.S. Pat. No. 4,574,800), Hocherl et al (U.S. Pat. No. 5,549,615) and McCorkle (U.S. Pat. Nos. 4,471,777 and 4,582,056) disclose similar devices which attach to a pacing lead close to the electrode. However, all of these devices have a disadvantage that they attach to the pacing lead in a localized area. Applying traction to the pacing lead and/or pacing lead removing devices according to the prior art can lead to the pacing lead's becoming distorted and/or breaking before the pacing lead is successfully removed from the patient. In addition, the prior art devices rely on either a form of entanglement with the coiled wire of the pacing lead, or some form of local distortion to the coil of the pacing lead in order to maintain a firm grip with the pacing lead removing apparatus while traction is applied to the apparatus. Consequently, this makes it difficult or impossible to remove a conventional device from the pacing lead in order to abort or restart the pacing lead removing procedure.
The expandable portions of the conventional devices also make it difficult or impossible to use other lead removing equipment and procedures in conjunction with those devices. For example, a substantially cylindrical and flexible catheter which has a central lumen is often slid over the pacing lead such that the pacing lead passes through the lumen of the catheter and the leading edge of the catheter is used to free fibrous growth from the pacing lead. Laser catheters are also known to slide over a pacing lead in which laser light is transmitted along the catheter in order to cut away fibrous tissue as the laser catheter is advanced along the pacing lead. Consequently, it is also desirable to have a pacing lead removing device which can attach internally to the pacing lead so as not to obstruct a catheter or laser catheter which may be used in conjunction with the pacing lead removing device. | {
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The present invention relates to an extended nip press for dewatering a pulp web in a paper-making machine which comprises two press rolls that form a press nip, the first press roll being retained in the axial direction at least at one end, and having first bearing blocks to hold first bearing pins of the first press roll, and having second bearing blocks to hold second bearing pins of the second press roll, and having tension elements by means of which the second bearing blocks can each be tensioned with respect to the first bearing blocks, the tension elements allowing a relative displacement of the press rolls in the axial direction.
An extended nip press of this kind is known from WO 92/17641.
In the known press apparatus, two press rolls, between which a press nip is formed, are arranged parallel to one another.
Since the first bearing blocks and the second bearing blocks are tensioned with respect to one another by means of tension elements, the result is a short force flow path for transfer of the pressing force in the press nip which does not stress any of the frame parts. The frame must therefore transfer only the dead weight of the press, but not the high pressing forces. The result is therefore a simpler, lighter, and more space-saving construction. In the known press apparatus, the tension elements consist of a center part similar to a leaf spring, and hammer-heads at the ends which are held in grooves on the bearing blocks. The bearing blocks are thus connected directly by means of the aforesaid tension elements. The tension elements, which are flexurally elastic in the axial direction of the press rolls, thus allow mutual deflection of the press rolls and a certain mutual axial displaceability of the press rolls during operation due to high pressing forces or due to changes in length which may, for example, be caused by temperature. When the press apparatus is unloaded, the tension elements are preloaded either not at all or only very slightly.
In the known apparatus, the first press roll is configured as a deflection compensated roll, i.e. the roll possesses a stationary supporting member or a yoke on which is rotatably mounted a roll shell that is hydraulically braced on the yoke, so that even when extraordinarily high pressing forces are present during operation, the roll shell can be adjusted to have practically deflection-free characteristics or even, if desired, to have a specific deflection, the yoke being capable of deflecting. At the same time, this considerably simplifies the construction of the bearings. In the known arrangement, the second press roller is configured as a shoe press roll, which again has a stationary supporting member over which a tubular pressing shell circulates. In the region of the press nip, this pressing shell runs over a press shoe which is adapted to the shape of the opposing roll, i.e. the first press roll which is embodied as a deflection compensated roll, thereby forming an extended press nip. Thus, an extraordinarily high pressing force can be generated in the region of the press nip, and at the same time a gradual increase in pressure upon entry into the press nip is possible.
When the width of the pulp web is smaller, in many cases the deflection compensated roll is replaced by a quasi-deflection-free solid roll, since the load is lower.
However, it has been found that in certain cases the tension elements of this pior art design may be subject to premature failure. | {
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Many infrared cameras today produce an image (IR image) of a scene using only energy in the far-infrared portion of the electromagnetic spectrum, typically in the 8-14 micron range. Images obtained using these cameras assign colors or gray-levels to the pixels composing the scene based on the intensity of the IR radiation reaching the camera's sensor elements. Because the resulting IR image is based on the target's temperature, and because the colors or levels displayed by the camera do not typically correspond to the visible light colors of the scene, it can be difficult, especially for novice users of such a device, to accurately relate features of interest (e.g. hot spots) in the IR scene with their corresponding locations in the visible-light scene viewed by the operator. In applications where the infrared scene contrast is low, infrared-only images may be especially difficult to interpret.
An infrared scene is a result of thermal emission and, not all, but most infrared scenes are by their very nature less sharp compared to visible images which are a result of reflected visible light. For example, considering an electric control panel of an industrial machine which has many electrical components and interconnections, the visible image will be sharp and clear due to the different colors and well defined shapes. The infrared image may appear less sharp due to the transfer of heat from the hot part or parts to adjacent parts.
When panning an area with an infrared camera looking for hot or cold spots, one can watch the camera display for a visible color change. However, sometimes the hot or cold spot may be small and the color change may go unnoticed. To aid in the identification of hot or cold spots, infrared cameras often indicate the hot spot or cold spot location via a visible cursor or other graphical indicator on the display. The temperature of such hot spots, calculated using well-known radiometric techniques (e.g., establishing or measuring a reference temperature), is often displayed nearby the cursor. Even with the color change and the hot spot indications, it can be difficult to accurately relate the hot spot (or other features of interest) in the camera display's IR imagery with their corresponding locations in the visible-light scene viewed by the operator.
To address this problem of better identifying temperature spots of interest, some cameras allow the operator to capture a visible-light image (often called a “control image”) of the scene using a separate visible light camera built into the infrared camera. The FLIR ThermaCam® P65 commercially available from FLIR Systems of Wilsonville, Oreg. is an example of such a camera. These cameras provide no capability to automatically align, or to merge the visible-light and infrared images in the camera. It is left to the operator to manually correlate image features of interest in the infrared image with corresponding image features in the visible-light image.
Alternatively, some infrared cameras employ a laser pointer that is either built into, or affixed to the camera. The FLIR ThermaCam® E65 commercially available from FLIR Systems of Wilsonville, Oreg. is an example of such a camera. This laser pointer projects a visible point or area onto the target, to allow the user to visually identify that portion of the target scene that is being displayed by the infrared camera. Because the laser pointer radiation is in the visible spectrum, it is not visible in the infrared image. As a result, the laser pointer is of limited value in infrared cameras. This can be problematic when the location of a hot or cold spot is difficult to identify. For example, large industrial control panels often have many components that are similar in shape and packed tightly together. It is sometimes difficult to determine the exact component that is causing a thermal event, such as a hot spot in the infrared camera image.
Other infrared temperature measurement instruments may employ either a single temperature measurement sensor, or a very small number of temperature sensors arrayed in a grid pattern. Single point instruments typically provide a laser pointing system to identify the target area by illuminating the point or area viewed by the single temperature sensor element, e.g. Mikron M120 commercially available from Mikron Infrared Inc. of Oakland, N.J. Alternatively, some systems employ an optical system that allows the user to visually identify the point in the target scene that is being measured by the instrument by sighting through an optical path that is aligned with the temperature sensor, e.g. Mikron M90 commercially available from Mikron Infrared Inc. of Oakland, N.J. Instruments with more than one sensor element typically provide a very crude infrared image made up of a small number of scene pixels, each with a relatively large instantaneous field of view (IFOV), e.g. IRISYS IRI 1011 commercially available from Advanced Test Equipment of San Diego, Calif. It can be very difficult to accurately identify features of interest using such images.
It is often difficult to focus infrared images because the infrared images do not typically have sharp resolution. For example, because of heat transfer by multiple processes from hot locations to adjoining locations, the images do not always have sharp resolution. This makes focusing the infrared image user subjective. It is desirable to make the focusing of infrared images less subjective. | {
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} |
This disclosure relates to an energy supply device for providing energy for an electrically operable vehicle. The disclosure further relates to a method for charging an energy supply device of this kind.
Many electrically operable vehicles require an electrical AC voltage, which is often a single- or three-phase voltage, in order to be supplied with power. The prior art discloses electrical energy storage devices which comprise a large number of energy cell modules which each comprise an electrochemical cell. Several of the energy cell modules are interconnected in series and form an energy supply branch. The electrochemical cells of the individual energy cell modules can be coupled into their energy supply branch by means of a coupling device, for example a 4-quadrant actuator. The voltage which is generated by an electrochemical cell can be coupled into the energy supply branch with a different polarity, so that both positive and also negative voltages can be generated by way of one energy supply branch. As an alternative, the electrochemical cell can be decoupled and bridged by generating a short circuit between the integration connections of the energy cell module in the series circuit, this being called the bypass mode. For the purpose of charging an energy cell module, the electrochemical cell of said energy cell module is coupled into the energy supply branch in such a way that the voltage of said energy cell module is directed against a charging voltage. For discharging purposes, or for supplying power to a load, the electrochemical cell is coupled into the energy supply branch with a polarity with which current flows through the load in the correct direction. Owing to the energy cell modules being coupled-in in a coordinated manner, an AC voltage with a frequency which can be freely selected within operating limits can be generated. An energy storage device of this kind is called a Battery Direct Inverter (BDI). A BDI behaves, at its energy supply connections, like a conventional converter with an intermediate circuit. Therefore, all loads which can be connected to a conventional converter can also be connected to a BDI. An example of a BDI of this kind from the prior art is disclosed in WO 2012/159811.
So-called range extenders are known for use in electrically driven vehicles. Said range extenders comprise a generator which can be driven by way of an internal combustion engine. The internal combustion engine is started when the energy content of the energy storage device falls below a critical threshold, and then drives the generator. The battery is charged by way of the generator via rectifiers. A drive motor is supplied with electrical energy from the battery via an inverter. In one variant, the drive motor can also be supplied with power from the generator. The battery is usually arranged in a DC voltage intermediate circuit. | {
"pile_set_name": "USPTO Backgrounds"
} |
1. Field of the Invention
The present invention relates to a hybrid vehicle comprising a vehicle driving engine, and a motor, which can drive the engine or generate electric power. In particular, the present invention relates to a hybrid vehicle comprising a control device for controlling a DC/DC converter, used for supplying electric power to auxiliary machines of the vehicle in response to energy generated by the motor.
2. Description of the Related Art
Conventionally, various vehicles such as an EV (Electric Vehicle) or an HEV (Hybrid Electric Vehicle) acquire electric energy by rotating a three-phase alternating current motor for generating the three phase alternating current electric power by use of an inverter deriving the electric energy from a high voltage main battery (electric power storage cell). In, addition, vehicles are provided with a DC/DC converter for converting a high voltage (for example, 144V) of the main battery to 12V for supplying electric power to a control computer actuated by 12V or auxiliary machines (such as the cooling fan, air conditioner, fuel pump and so on), and an auxiliary battery for storing an electric power obtained by converting by a DC/DC converter.
However, in the above-described conventional vehicles, the DC/DC converter is always operated deriving energy from the main battery in order to actuate the auxiliary machines, and a problem arises in that the energy of the main battery cannot always be sufficiently utilized for rotating the motor for driving. In order to solve such a problem, a control device has been proposed in Japanese Unexamined Patent Application, First Publication No. Hei 7-79505. This control device comprises a vehicle travel detect signal generating device for generating a vehicle travel detect signal while the vehicle travels (vehicle is driving) and when the vehicle travels, the control device sets the output voltage of the DC/DC converter at a lower voltage (a voltage that cannot charge the auxiliary battery) which is lower than the output voltage at the time of vehicle stop. Consequently, a part of the electric power supplied to the DC/DC converter at the vehicle stop can be used for rotating the motor during the vehicle travels.
However, since the conventional control device merely distributes the electric power of the main battery, the conventional control device cannot cope with the output voltage drop of the battery caused by the rush current flowing in the auxiliary machines at the time of starting the DC/DC converter.
The above effect will be explained with reference to FIG. 6. As shown by line b in FIG. 6, for example, when the DC/DC converter is actuated, the output current of the DC/DC converter is rapidly increased due to the rush current to the auxiliary machines, as shown by line d in FIG. 6. The internal resistance of the main battery is normally in a range of 0.1 to 0.3 xcexa9, but the resistance increases at a level of 10 xcexa9 when the main battery is placed in a low temperature atmosphere. In addition, when a current flows rapidly in the DC/DC converter when the internal resistance is high, the output voltage of the main battery may cause a large voltage drop, as shown by line e in FIG. 6.
As a result, depending upon the increased internal resistance, the output voltage of the main battery may be reduced to below the lower limit voltage, shown by line e in FIG. 6, of the main battery (power storage cell). Excessive reduction of the output voltage causes an overdischarge of the battery, degradation of the battery, and deterioration of the service life of the battery. The control battery voltage, shown by line c in FIG. 6, represents the voltage applied to the auxiliary battery. As shown by line d in FIG. 6, even when the output current from the DC/DC converter increases rapidly, since the rapid increase is caused by the rush current, the voltage applied to the auxiliary battery increases gradually.
In order to solve the aforementioned problem, a technique to prevent the excessive voltage drop of the main battery has been proposed in the hybrid vehicle comprising a travel driving engine and a motor which drives the engine or which can generate electric energy. The technique to prevent the excessive voltage drop in the hybrid vehicle is carried out such that by using the motor as a motor generator, the discharge from the main battery is reduced to be as low as possible by controlling generation of the motor-generator driven by the engine in response to the input current to the DC/DC converter.
However, the above-described technique encounters a limit. This is, associated with the late response of the secondary air valve used for stabilizing the engine rotation when the engine is in the idle state, even when it is desired to compensate for the electric energy consumed by the DC/DC converter by one time generation by the motor generator, the engine output does not follow the increase of the generation torque of the motor generator, which results in causing the engine encountering stall or rotation fluctuation. When the generation torque of the motor generator is slowly increased so as to meet the late response of the secondary air valve, it will take time to convert the energy generated by the motor generator to the output voltage of the DC/DC converter, and, as a result, insufficient power will be compensated by the discharge of the battery, causing further voltage drop of the main battery.
The present invention has been made to solve the aforementioned problems, and it is the object of the present invention to provide a hybrid vehicle and a control method therefor which, while maintaining the stabilized idle rotation of the engine, is capable of preventing the temporary voltage drop of the battery by controlling the discharge of the battery at the time of starting the DC/DC converter at low temperatures.
The first aspect of the present invention provides a hybrid vehicle comprising an engine (for example, an engine 7 in the embodiment) for driving the vehicle, and a motor (for example, a motor generator 6 in the embodiment) for driving the engine or for generating electric energy, a battery (for example, a high voltage battery 1 in the embodiment), a DC/DC converter (for example, a output variable DC/DC converter 2 in the embodiment) for supplying energy to the auxiliary machines (for example, a controller computer and auxiliary machines 3 in the embodiment), a temperature detecting device (for example, a temperature sensor 11 in the embodiment), and an output voltage increasing device (for example, motor controllers 8 and 21 in the embodiment), when the temperature of the battery is below a predetermined temperature, the output voltage increasing device sets the output voltage at a predetermined voltage and starting the DC/DC converter, and, after starting the DC/DC converter, and gradual increases the output voltage of the DC/DC converter from the predetermined voltage.
By constituting the hybrid vehicle as described above, when the engine is in the idle state and the electric energy generated by the motor is low, and when the temperature of the battery is below a predetermined temperature, the DC/DC converter is activated at a low output voltage, and the output voltage of the DC/DC converter is increased gradually from the voltage at the time of activation so that the electric power consumed by the DC/DC converter can be increased gradually.
According to the second aspect of the present invention, the hybrid vehicle comprising an engine (for example, an engine 7 in the embodiment) for driving the vehicle and a motor (for example, a motor generator 6 in the embodiment) for driving of the engine or for generating electric power, and a battery (for example, a high voltage battery 1 in the embodiment), which is charged by electric power generated by the motor, a DC/DC converter (for example, a output variable DC/DC converter 2 in the embodiment), capable of outputting a variable output voltage, and outputting a control voltage for controlling auxiliary machines of the vehicle by decreasing the voltage of the battery, a temperature detecting device (for example, a temperature sensor 11 in the embodiment) for detecting a temperature of the battery; and an output voltage switching control device (for example, a motor controller 8 and 21 in the embodiment), which activates the DC/DC converter by setting the output voltage of the DC/DC converter at a first voltage when the temperature of the batter is below the predetermined temperature, and which carries out a control operation to switch the output voltage from the first voltage value to a second voltage value, which is higher than the first voltage.
By constituting the hybrid vehicle as described above, when the engine is in the idle state and the electric energy generated by the motor is low, and when the temperature of the battery is below a predetermined temperature, the DC/DC converter is activated at a low output voltage, and then the output voltage of the DC/DC converter is switched to a higher voltage so that the electric power consumed by the DC/DC converter can be increased in a stepwise manner.
According to the third aspect of the present invention, in the above hybrid vehicle, after activating the DC/DC converter, the output voltage increasing device gradually increases the amount of electric power generated by the motor in response to the output response characteristic of the engine, and gradually increases the output voltage of the DC/DC converter in response to the increase amount of electric power generated by the motor.
By constituting the hybrid vehicle as described above, when the engine is in the idle state and the electric energy generated by the motor is low, and when the temperature of the battery is below a predetermined temperature, the DC/DC converter is activated at a low output voltage, and while the amount of electric power generation is increased at a speed which does not disturb the idle rotation of the engine, the output voltage of the DC/DC converter is gradually increased, so that it becomes possible to gradually increase the electric power consumed at the output side of the DC/DC converter by an increasing amount of electric power generated by the motor.
According to the fourth aspect of the present invention, after the DC/DC converter is activated, the output voltage switching control device gradually increases the amount of electric power generated by the motor in response to the output response characteristic of the engine, and switches the output voltage of the DC/DC converter from the first voltage to the second voltage.
By constituting the hybrid vehicle as described above, the DC/DC converter is activated at a low output voltage when the engine is in the idle state and the electric power generated by the motor is low, and the output voltage of the DC/DC converter is switched from a low voltage to a high voltage while the output voltage of the DC/DC converter is increased gradually at a low speed so as not to disturb the idle rotation of the engine; thereby the electric power consumed at the output side of the DC/DC converter can be increased at the state, where the electric power generated by the motor is ensured.
According to the fifth aspect of the present invention, the hybrid vehicle further comprising a electric power comparison device (for example, the high voltage electric power information acquisition portion 14, and the low voltage electric power information acquisition portion 17, and steps S5 to step S7 in the embodiment) for comparing between the electric power generated by the motor and the electric power consumed by the DC/DC converter, and when it is determined by the electric power comparison device that the electric power generated by the motor is equivalent to the electric power consumed by the DC/DC converter, the output voltage switching control device carries out a control operation to switch the output voltage of the DC/DC converter from the first voltage to the second voltage.
By providing the hybrid vehicle as described above, the amount of electric power generated by the motor can be dynamically controlled so as to meet the electric power consumed by the DC/DC converter. It is also possible to increase the electric power to be consumed at the output side of the DC/DC converter by switching the output voltage of the DC/DC converter from the low voltage at the time of start to a higher voltage while the electric power generated by the motor is sufficiently preserved.
According to the sixth aspect of the present invention, the hybrid vehicle further comprising a torque comparison device (for example, the high voltage electric power information acquisition portion 14, and the low voltage electric power information acquisition portion 17, the rotation sensor 19, and steps S15 to step S19 in the embodiment) for comparing between the electric power generation torque by the motor and the target electric power torque, and when it is determined by the torque comparison device that the power generation torque by the motor is equivalent to the target power generation torque, the output voltage switching control device carries out a control operation to switch the output voltage of the DC/DC converter from the first voltage to the second voltage.
By constituting the hybrid vehicle as described above, the output voltage of the DC/DC converter can be switched from the low voltage at the time of activation to the higher voltage when it is determined that the electric power obtained by generation of the motor by the comparison between the power generation torque of the motor and the target power generation torque for obtaining electric power consumed by the DC/DC converter, so that it is possible to increase the amount of electric power to be consumed at the output side of the DC/DC converter in the state where the electric power by the motor is sufficiently reserved.
According to the seventh aspect of the present invention, in the above hybrid vehicle, the torque comparison device calculates the target power generation torque from the electric power consumed by loads connected to the DC/DC converter and from a number of rotation of the motor.
By constituting the hybrid vehicle as described above, the torque comparison device is capable of dynamically calculating the target power generation torque in conformity with the change of the electric power consumed at the output side of the DC/DC converter.
The eighth aspect of the present invention provides a method of controlling a hybrid vehicle is provided which comprises an engine (for example, an engine 7 in the embodiment) for driving the vehicle, a motor (for example, a motor generator 6 in the embodiment) for driving the engine or for generating electric power, a battery (for example, a high voltage battery 1 in the embodiment), to be charged by electric power generated by the motor; a DC/DC converter (for example, an output variable DC/DC converter 2 in the embodiment), capable of outputting a variable output voltage, and outputting a control voltage for controlling auxiliary machines of the vehicle (for example, a control computer and auxiliary machines 3 in the embodiment) by depressing the voltage of the battery, and a temperature detecting device (for example, a temperature sensor 11 in the embodiment) for detecting a temperature of the battery, wherein the method of controlling the hybrid vehicle further comprises; a control step for activating the DC/DC motor while setting the output voltage of the DC/DC converter at a predetermined voltage, when the temperature of the battery is below a predetermined temperature, and a control step, after the DC/DC converter has been activated, for gradually increasing the output voltage of the DC/DC converter from the predetermined voltage.
The ninth aspect of the present invention provides a method of controlling a hybrid vehicle comprising an engine (for example, engine 7 in the embodiment) for driving the vehicle, a motor (for example, motor generator 6 in the embodiment) for driving of the engine and for generating electric power, a battery to be charged by electric power generated by the motor; a DC/DC converter, capable of outputting a variable output voltage, and outputting a control voltage for controlling auxiliary machines of the vehicle by depressing the voltage of the battery, and a temperature detecting device for detecting a temperature of the battery, wherein the method of controlling the hybrid vehicle comprises a step for activating the DC/DC motor while setting the output voltage of the DC/DC converter at a first voltage, when the temperature of the battery is below a predetermined temperature, and a step, after the DC/DC converter has been activated, for switching the output voltage of the DC/DC converter from the first voltage to the second voltage which is higher than the first voltage. | {
"pile_set_name": "USPTO Backgrounds"
} |
The conventional distributor for an internal combustion engine is shown in FIG. 1. A distributor housing 10 mounted in an internal combustion engine (not shown) consists of two portions, namely an upper distributor housing portion 11 and a lower shaft-bearing portion 12. The lower portion 12 has a cylindrical shape and has an axial bore 13 in which a rotary shaft 14 is inserted and supported at the upper end by a bearing member 15 and at the lower end by a metal sleeve 16. The rotary shaft 14 at the upper end is integrally connected with a bushing 17 upwardly extending axially of an enlarged space 18 in the upper portion 11 of the housing 10. The upper portion 11 at its upper end is engaged with and closed by a cap 19 secured to the housing 10 by screws 20. The bushing 17 has a rotary disc 21 secured vertically divided between upper and lower parts 17a, 17b fixed by a screw 22.
The rotary disc 21 extends radially and outwardly of the bushing 17. The bushing 17 at its top end is connected with a distributor rotor 23 which is secured by inserting the upper end of the bushing 17 into a bore provided in the distributor rotor 23 and fixed by a screw 24. The distributor rotor 23 is made of synthetic resin and at its upper surface has a rotor electrode 25. The rotor electrode 25 at one end is positioned about the rotating axis of the rotor 23 and is slidably connected with a contact 26 provided at the lower end of a central electrode 27, which is arranged in alignment of the rotary axis of the distributor rotor 23 and secured in a bore provided in the top wall of the cap 19. The electrode 25 at its other and outer end moves and passes near the side wall of the cap 19 and, successively, a plurality of circumferential electrodes 28 with a discharge gap. The circumferential electrodes 28 are positioned about the central electrode 27 circumferentially of the top wall of the cap 19 and spaced one to the other with a predetermined angular interval.
The shaft 14 is rotated synchronously with the revolution of the internal combustion engine and rotates the disc 21 integrally therewith. The disc 21 has a radial slit at a position at which it faces to a photoelectric pickup. The photoelectric pickup consists of a light-emitting element 29 and a light-receiving element 30 which are arranged opposite to each other with respect to a symmetric plane containing the rotary disc 21. The unit 31 including the light-emitting and light-receiving elements 29, 30 has also a signal processing circuit 32 for processing output signal from the photoelectric pickup. 31a is an element that acts to protect the unit from radio frequency interference (RFI).
In the above-mentioned apparatus, the shaft 14 rotates synchronously with the revolution of the engine (not shown). In the rotation of the shaft 14, the slit in the rotary disc 21 crosses an infrared light beam and intermittently passes it between the light-emitting element 29 and the light-receiving element 30. The corresponding output signal from the light-receiving element 30 is processed for its wave-form shaping and the like by signal processing circuit 32, thereby to obtain a predetermined crank angle signal or cylinder discriminating reference signal. Such a signal determines ignition time when the ignition high voltage is supplied to the central electrode 27 from where it is successively distributed to the plurality of circumferential electrodes 28 through the contact 26 and the rotor electrode 25 so that ignition is provided in each cylinder of the internal combustion engine (not shown).
In a conventional distributor as described above, however, electrical noise from outside is induced into the signal processing circuit 32. This may cause operational errors, in particular erroneous ignition and missing ignition of the internal combustion engine.
As the result of careful investigation on this problem, the following cause therefor has been found. When the center electrode 27 is supplied with ignition high voltage, this voltage is induced to the distributor rotor 23, the bushing 17 and the shaft 14. Usually the shaft 14 is connected with the housing 10 for grounding thereof. However, at the motion transmitting portion at the bearing 15 and between the shaft 14 and the sleeve metal 16, there can exist some clearance or gap which may cause the the shaft to lose contact with its electrical ground, i.e., to be temporarily ungrounded during high acceleration or deceleration of the engine. A high voltage which is induced to the bushing 17, the shaft 14, etc., in this state is also induced to the signal processing circuit 32 and may cause errors in its operation. | {
"pile_set_name": "USPTO Backgrounds"
} |
1. Field of the Invention
The invention relates to fasteners for clothing. More particularly, the invention relates to an adjustable fastener for a brassiere or similar garment.
2. State of the Art
Many articles of clothing are provided with adjustable fasteners. In particular, brassieres are typically provided with an adjustable fastener for connecting right and left center backs of the garment. These fasteners usually include one or more hooks and multiple eyelets spaced apart from each other so that the snugness of the garment eye can be adjusted by mating the hook(s) with the appropriate eyelet(s).
The known brassier fasteners have several disadvantages. First, being located at the back of the garment, they are difficult to manipulate. Second, the hooks and eyelets are typically made of metal and feel uncomfortable pressing against the back of the wearer. Third, the fastener is typically thicker than the garment to which it is attached and is visible through outerwear as a bump.
Many attempts have been made to provide a brassier fastener which is easy to operate, comfortable to the wearer and less visible. While these fasteners may solve some of the problems described above, they typically do not solve all of the problems and often introduce new problems. For example, in attempting to overcome the problems described above, many brassier fasteners sacrifice stability for comfort. This permits the fastener to accidentally detach. Also, some fasteners which attempt to solve the problem of visibility have actually increased the difficulty in operation of the fastener.
The previously incorporated co-owned U.S. patent discloses an adjustable fastener that includes a male part and a female part, both of which are made of soft pliable, sewable plastic. The female fastener part has three spaced apart openings. Each opening has a broad portion and a narrow portion. The male fastener part has a base with an upstanding riser with a flange at the end of the riser. The flange is dimensioned to fit into the broad portion of each opening in the female fastener part and the riser is dimensioned to fit snugly into the narrow portion of each opening in the female fastener part. The back side of the male fastener part is provided with parallel grooves which enhance gripping when releasing the fastener. Both of the fastener parts have a pair of parallel flanges at one end between which the garment back end is inserted and secured to the fastener part. The fastener parts thus become extensions to the garment and are easily visible as such unless covered with additional material. The fastener parts are preferably attached to the garment's center backs or back straps so that the openings in the female fastener part face the back of the wearer and the riser and flange on the male fastener part face away from the back of the wearer. The back of the female fastener part is preferable covered with fabric and/or bears a trademark or a design.
According to one embodiment, the flange on the male fastener part is substantially circular and has a centrally located nub rising from its surface. The broad portion of each opening in the female fastener part is substantially circular and the narrow portion of each opening in the female fastener part has a nub-receiving well. This structure adds stability to the fastener, preventing accidental unfastening.
According to another embodiment, the flange on the male fastener part is substantially elliptical. The broad portion of each opening in the female fastener part is substantially elliptical and a pair of ears extend between the broad portion and the narrow portion of each opening in the female fastener part. This structure also adds stability to the fastener, preventing accidental unfastening.
According to one method of manufacture, both parts are injection molded and are fastened to brassier center backs by sewing. According to another method of manufacture, the male fastener part is injection molded, but the female fastener part is made from a laminate structure which includes two outer layers and two inner layers. The outer layers are made of a soft fabric material and the inner layers are made of soft plastic. One of the plastic layers has the openings as described and the other plastic layer has thick portions which surround the openings in the other plastic layer to create a space for receiving the male fastener part. The plastic spacer is made by embossing a plastic sheet and the outer fabric layers are made from a single layer which is folded.
It has since been discovered that some of the features of the fastener described in the previously incorporated patent are, in fact, disadvantages. For example, the manner in which the fastener parts are attached to the garment is relatively complicated when it is desirable to make the fastener less visible. In addition, while the fastener is made of soft plastic, its presence is still detectable by the wearer on the wearer's back. Furthermore, the overall size of the fastener parts is relatively large making them more easily seen and felt. | {
"pile_set_name": "USPTO Backgrounds"
} |
Surfactants have been widely formulated in cleansing products in cosmetic applications. The major function of surfactants in rinse off products is to cleanse the skin and hair of fatty and water-soluble impurities, however, surfactants meanwhile also cause irritation.
In skin care applications, surfactants function to remove normal skin lipids. The natural water-lipid film that functions to protect the skin is disturbed with every wash. Hydrophilic groups of the negatively charged polar surfactant anions react with the weakly cationic, positively charged amino groups of proteins of the skin and mucosa. Therefore, surfactants are known for their irritancy to eyes and defatting to skin, this is especially the case for anionic surfactants, which react with proteins in the skin and mucous membranes. The similar defatting effect from surfactant is also true in hair care. The most critically assessed surfactants are sodium lauryl and laureth sulfate, which can significantly cause hair harshness after the shampooing.
Another important aspect of surfactants is their foaming properties. Consumer's perception of foam is physiologically related to the efficacy of cleansing. The products that generate large volume and size of foam during application are often perceived to have better a cleansing effect. The typical surfactants of fatty alcohol sulfates generate good amounts of foam with medium to large foam bubble sizes.
In both hair care and skin care applications, many polymeric conditioners and emollients are inherently hydrophobic and they tend to be difficult to be spread and can leave deposits left on skin or hair if the formulation has poor wetting properties. Therefore, wetting is another important property to be assessed. Surface tension is used as one of the tools for the evaluation of wetting property. Common surfactants, e.g. fatty alcohol sulfates, have low surface tension, which helps to enhance the wetting attribute in formulations for hair and skin.
One major concern for surfactants is their irritancy. Many studies have been done over the decades to reduce the irritancy and defatting disadvantages of surfactants. However, over the course of the development of low irritancy surfactants, scientists often have a dilemma: in exchange for low irritancy the foam property was sacrificed.
An alternative surfactant to fatty alcohol sulfates is therefore desired. | {
"pile_set_name": "USPTO Backgrounds"
} |
1. Field of the Invention
The present invention relates to processes for the extraction of crude oil from underground deposits.
2. Discussion of the Background
In the extraction of oil from source rock primary extraction processes generally only manage to raise a fraction of the oil originally present. In this case the oil reaches the earth's surface as a consequence of the natural pressure in the deposit. In secondary oil extraction, water is usually forced into one or more production wells in the formation and the oil is driven to one or more injection wells and then brought to the earth's surface.
This so-called water flooding as a secondary measure is relatively cheap and is used correspondingly frequently. But in many cases this method only leads to little additional oil extraction from the deposit.
Effective displacement of the oil, which is expensive but which is economically necessary in view of the future scarcity of oil, is achieved by tertiary measures. These are processes in which either the viscosity of the oil is lowered and/or the viscosity of water used for secondary flooding is raised and/or the interfacial tension between water and oil is lowered.
The majority of these processes can be classified as (1) dissolving or mixing flooding, (2) thermal oil extraction processes, (3) surfactant or polymer flooding or (4) as a combination of several of the processes mentioned.
Dissolving or mixing processes consist of injecting a solvent for the crude oil into the deposit. This solvent can be a gas and/or a liquid.
Thermal extraction processes include the injection of steam or hot water or they take place as underground combustion.
In the surfactant processes differentiation is made, depending on the surfactant concentration and possibly on the surfactant type and additives, between surfactant-assisted water flooding, micellar flooding and emulsion flooding. Surfactant-assisted water flooding is a process which, for example, can serve to increase the injection efficiency of injection wells or represents a "low-tension process." The action of the surfactant flooding is based primarily on a sharp reduction of the interfacial tension between oil and flooding water. The wettability of the rock surface and the mobility conditions are also of great importance. Favorable mobility conditions between oil and water are achieved by means of polymers.
These methods are not fully satisfactory however because they do not provide fully satisfactory results with varying levels of salinity in the deposits or with varying temperatures in the deposits. | {
"pile_set_name": "USPTO Backgrounds"
} |
The present invention relates to an extramedullary proximal tibial guide. In the prior art, proximal tibial saw guides are known. However, Applicant is unaware of any such device including all of the features and aspects of the present invention.
Several problems persist in surgical procedures which are employed to install a knee joint prosthesis on a patient. One of the key problem areas concerns resection of the proximal tibia and the present invention is designed to facilitate such resection in a safer, more effective manner.
When resecting the proximal tibia, the patellar tendon must be everted and turned laterally. The attachment of the patellar tendon on the tibial tubercle is quite close to the location where resection is to take place and, as such, it is important to provide an instrument which will protect the patellar tendon during the resection procedure. Applicant is unaware of any prior art tibial saw guide which provides this protection.
In a further aspect, in prior art proximal tibial saw guides, the surface of the guide defining the bottom extent of the saw guide slot traditionally is specifically shaped to mimic the shape of the proximal tibia. As such, with the structure of the saw guide defining the bottom of the slot so that the bottom of the slot on both side walls thereof is flush with the proximal tibial surface, it is not possible for the surgeon to specifically visualize precisely how far from the extreme proximal end of the tibia the resection will take place. As such, a need has developed for a proximal tibial saw guide which may accurately and precisely guide resection of the proximal tibia while permitting the surgeon to visualize the precise location of the resection prior to commencing with the resection.
In a further aspect, while prior art proximal tibial saw guides have included features permitting macro adjustment of the particular position Of the saw guide on the proximal tibia, a need has developed, as surgical techniques have become more precise, to devise a cutting head which may be held in such a manner that micro adjustment is possible. Such micro adjustment requires constraint of the tibial saw guide with fastening means permitting micro adjustments including angulatory adjustments. This problem also arises due to the fact that prior art surgical saw guides for resecting the proximal tibia engage the proximal tibia with a large surface area of engagement. This large surface area of engagement makes it more difficult to perform micro adjustments due to the frictional forces caused by such a large surface area. As such, a need has developed for a surgical saw guide for resection of the proximal tibia which addresses these deficiencies in the prior art.
In prior art proximal tibial saw guides, in order to perform the various adjustments in configuration of the device to permit accommodation to a particular surgical site, large adjustment knobs are often provided. These knobs can sometimes interfere with the surgical procedure and, even where such interference is subtle, a need has developed to provide adjustment means which is more aesthetic than known adjustment means while maintaining full functionality.
In a further aspect, a need has developed for a securing device to secure the ankle bracket to the ankle of the patient which may easily be adjusted while providing secure attachment.
It is with these problems in mind that the present invention was developed. | {
"pile_set_name": "USPTO Backgrounds"
} |
In 2007, statistics show that about 84% of the US population subscribed to a form of wireless mobile phone service. Approximately 6% of automobile drivers admitted to using hand-held phones while driving. The actual number of drivers using wireless devices is likely much greater. Researchers have shown that using mobile phones while driving is four times as likely to get into crashes, and the increased crash risk is similar for hands-free and hand-held phones.
The U.S. Department of Transportation has launched numerous programs and initiatives to reduce traffic-related fatalities and injuries. Many states explicitly prohibit talking, text-messaging or playing video games on hand-held mobile phones while driving. Additionally, a number of states, such as California, have passed laws banning or restricting young drivers (under age 18) from using mobile phones, or other types of mobile devices while driving. However, a recent study in North Carolina finds that teenagers seem to ignore such restrictions. A ban on the use of wireless devices by teenagers while driving was enacted in the Spring of 2007. The study found that approximately 11% of teenage drivers observed departing 25 high schools were using mobile phones during the two months before the restrictions were enacted, while about 12% of teenage drivers were observed using mobile phones during the five months after the enactment of the restrictions.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. | {
"pile_set_name": "USPTO Backgrounds"
} |
The present invention relates to a liquid crystal display used for a liquid crystal projector and a sheet polarizer for the liquid crystal display.
A liquid crystal projector projects an image on a liquid crystal panel onto a screen on an enlarged scale using a projecting optical system. FIG. 3 shows one configuration of an optical system of a related art liquid crystal projector. The liquid crystal projector includes a lamp 101 for emitting light, a condenser lens 102 for condensing the light emitted from the lamp 101, an incoming light side sheet polarizer 103, an aperture 104, a liquid crystal panel 105, an outgoing light side sheet polarizer 106, and a projecting lens 107. The incoming light side sheet polarizer 103, which is referred sometimes to "a sheet polarizer before liquid crystal", allows only a specific polarized light component of the light condensed through the condenser lens 102 to pass therethrough. The aperture 104 has an aperture ratio of typically 50% for allowing 50% of the light component having passed through the incoming side sheet polarizer 103 to pass therethrough. The liquid crystal panel 105 has a number of pixels, and it allows the light component having passed through the aperture 104 to enter therein. The pixels are arranged, for example, in a grid pattern and are each capable of selecting a suitable optical rotatory power under a suitable electric field. The outgoing light side sheet polarizer 106, which is sometimes referred to as "a sheet polarizer after liquid crystal", is stuck on an outgoing light side face of the liquid crystal panel 105, and it allows only a specific polarized light component of the outgoing light component from the liquid crystal panel 105 to pass therethrough. The projecting lens 107 is adapted to project the light component having passed through the outgoing side sheet polarizer 106 on a screen 108 on an enlarged scale.
The liquid crystal panel 105 includes a drive substrate 111 on which a switching element using, for example, a thin film transistor (TFT) is formed for each pixel; a counter substrate 112 arranged opposite to the drive substrate 111 with a specific distance put therebetween; and liquid crystal 113 filled between the drive substrate 111 and the counter substrate 112. The liquid crystal panel 105 has, if needed, a color filter and the like for color display. In such a liquid crystal panel 105, the counter substrate 112 is disposed on the incoming light side; the drive substrate 111 is disposed on the outgoing light side; and the outgoing light side sheet polarizer 106 is stuck on the drive substrate 111.
In the liquid crystal projector shown in FIG. 3, light emitted from the lamp 101 is condensed through the condenser lens 102, and the condensed light enters in the incoming light side sheet polarizer 103. Only a specific polarized light component passes through the incoming light side sheet polarizer 103 as linearly polarized light. In the example shown in FIG. 3, at the incoming light side sheet polarizer 103, the quantity of transmitted light is taken as 3,000,000 lm, and the quantity of absorbed light is taken as 4,500,000 lm. The light having passed through the incoming light side sheer polarizer 103 enters in the liquid crystal panel 105. Assuming that the rate of aperture area is 50%, 50% of the incoming light component is cut off, and the remaining light component is selected in terms of optical rotatory power for each pixel and goes out of the liquid crystal panel 15 as elliptically polarized light suitable for each pixel. In the example shown in FIG. 3, at the liquid crystal panel 105, the quantity of transmitted light is taken as 1,500,000 lm, and the quantity of absorbed light is taken as 1,500,000 lm. The outgoing light from the liquid crystal panel 105 enters in the outgoing light side sheet polarizer 106. Here, the light component passes through the outgoing light side sheet polarizer 106 selectively for each pixel in accordance with the optical rotatory power for each pixel in the liquid crystal panel 105. In the example shown in FIG. 3, at the outgoing light side sheet polarizer 106, the quantity of transmitted light is taken as 0-1,350,000 lm, and the quantity of absorbed light is taken as 150,000-1,500,000 lm. The light having passed through the outgoing light side sheet polarizer 106 is projected on the screen 108 on an enlarged scale by the projecting lens 107, to form an image.
In the related art transmission type liquid crystal projector shown in FIG. 3, the two organic (iodine, dye) based sheet polarizers 103 and 106, each of which is substantially of the direct-vision type, are essentially provided as optical members before and after the liquid crystal panel 105, respectively. Also the existing liquid crystal projector is required to be increased in quantity of light, because the efficiency of the lamp 101 is low and the image is dark. In the related art liquid crystal projector, however, since the quantities of light absorbed by the sheet polarizers 103 and 106 become larger with the increased quantity of light, there is a fear that the sheet polarizers 103 and 106 are degraded by thermal energy or the like caused by light absorption at the sheet polarizers 103 and 106. As a result, the entire performance of the liquid crystal projector cannot be enhanced only by improving the durability of a single sheet polarizer with the related art configuration being left as it is.
In the related art liquid crystal projector, the sheet polarizers 103 and 106 and the liquid crystal panel 105 are air-cooled. However, for a liquid crystal projector used for AV (audio video), air-cooling cannot be sufficiently performed because of a limitation in terms of noise.
A thin polarizer directly contributing to polarization, which is low in humidity resistance, is generally used in the form of a sheet polarizer in which the polarizer is held between resin made protective layers for increasing the durability. However, the resin forming the protective layer generates heat, and thereby it shortens the service life of the sheet polarizer. Further, the resin having a low heat conductivity is liable to store the heat generated therein.
As the incoming light side sheet polarizer, an inorganic type polarizer such as a polarization beam splitter has been developed. However, the polarization beam splitter is very high in cost, and it is difficult to be adopted as a product for consumer use. For this reason, it is expected to develop a planar type polarization beam splitter; however, it is in the course of development and is poor in mass-production.
To increase the cooling efficiency of the liquid crystal panel 105, the outgoing light side sheet polarizer 106 should be separated from the liquid crystal panel 105; however, according to the existing technique, since unnecessary light caused by a difference in refractive index between the drive substrate 111 and air exerts adverse effect on operation of switching elements using TFTs or the like in the drive substrate 111 and in the worst case it makes impossible the driving, there is an limitation that the outgoing light side sheet polarizer 106 must be stuck on the drive substrate 111. Specifically, in the existing liquid crystal projector, the liquid crystal panel 105 must be used in such an undesirable state for cooling that the liquid crystal panel 105 and the outgoing light side sheet polarizer 106, each of which is a source of heat generation, must be integrated with each other. | {
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The present disclosure relates generally to test systems, and more particularly to a system and method for improving communications between a device under test (DUT) and a tester.
The increasing functional complexity of electronic components and systems has made integrated circuit (IC) testing challenging, particularly under the constraints of making a continuous improvement in quality and a continuous reduction in cost. The cost of manufacturing a transistor continues to improve as predicted by Moore's Law. Test costs, however, have not generally followed the same price/performance curve as the transistor and are therefore becoming a higher percentage of the total manufacturing cost of a chip.
Today, manufacturers of automatic test equipment (ATE) offer test systems to address the increasingly complex task of testing advanced multi-function, ICs such as system-on-a-chip (SoC). However, many commercially available ATE systems are complex, proprietary, not easily flexible to meet changing test conditions, often require additional heat removal systems, and typically cost several million dollars, thereby making them unattractive for use in a cost driven manufacturing environment. Recently, many semiconductor manufacturers, and some ATE suppliers have introduced low cost test systems such as a very low cost tester (VLCT). The VLCT system may be used as a standalone test system, or used in combination with a conventional ATE system. The VLCT systems typically provide lower test costs, and are more flexible in meeting the changing test conditions, making them more attractive in the cost driven manufacturing environment.
VLCT systems may be used for performing mixed signal (e.g., analog and digital) testing, which may include radio frequency (RF) analog signals and high speed digital signals. However, due to cost considerations, many of the VLCT systems may provide a limited amount of performance, and may have a limited capacity. For example, some VLCT systems may have a limited data throughput for testing, e.g., the systems may include a clock that is limited to 30 megahertz (MHz) frequency. These VLCT systems may be unable to perform high speed digital signal data capture or data sourcing for testing high speed chips having clock rates greater than 30 MHz.
Some of these limitations may result in operating the VLCT at the lower clock speeds, e.g., 30 MHz, thereby increasing the time, and reducing the efficiency to test each DUT. The mismatch in clock speeds may cause problems in maintaining time synchronization between the VLCT and the DUT. The additional time needed for testing each DUT at the lower clock speed is magnified at the manufacturing process level when millions of DUT's may be tested in a day. As a result, some of the limitations of the VLCT systems may inadvertently slow down the production rate, and may contribute to an overall increase in the cost of testing. | {
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This invention relates to cassettes of the type including a length of tape having end portions wound around two reels rotatably mounted in a housing with a portion of the tape extending between the reels, and a tab for limiting slack in the tape between the reels.
Slack or looseness in the length of tape between the reels in such a cassette can arise when the cassette is being transported or is otherwise separated from a recording or reproducing device. While some cassettes have locks that restrict rotation of the reels when the cassette is not in a machine, it is still possible that one or both of the reels within the cassette may turn in the direction of unwinding to develop slack. Slack in the tape can also occur when the tape is engaged with a recording or reproducing device. Typically, the recording or reproducing device has spindles which engage the two reels. If driving and braking of the reels during the operation of the recording or reproducing apparatus is not synchronous, slack in the tape will develop. This slack may cause the tape to jam within the cassette or within the recording or reproducing device engaging the tape.
Cassettes having tabs to limit the slack in the tape are known in the art. For example, a flexible resilient slack limiter tab is described in U.S. Pat. No. 3,797,799. One end of the slack limiter tab biases tape in a cassette into engagement with a fixed support surface to cause a slight resistance to motion of the tape. The slack limiter tab is secured in position by cementing or adhesively fastening a portion of the tab to the housing of the cassette.
Adhesively fastening a slack limiting tab in a cassette requires more time than is desirable, particularly for highly automated assembly. Also adhesively fastened slack limiter tabs may become misaligned during installation, or the adhesive may fail after installation. Misalignment of the tab may cause excessive wear on the tape or improper performance of the tape. Adhesive failure, which can occur due to age, humidity, or stress on the tab due to misalignment during installation, may result in the tab being dislodged from its desired position, and even jamming of the dislodged tab in the cassette or in a machine in which the cassette is mounted. | {
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1. Field of the Invention
The present invention generally relates to integrated circuits and more particularly to an improved integrated circuit that includes passive devices formed over active devices using a conductive polymer.
2. Description of the Related Art
Integrated circuits for wireless applications are driven to higher levels of integration to reduce the processing and design costs. To integrate passive components such as RF (radio frequency) circuits with the digital core is highly desirable. Today's mobile cellular phone has hundreds components. Most of them are passive devices. To integrate them into a single chip is not only cost effective, but also can reduce the power consumption in the system. However, the passive components, such as inductors, capacitors and resistors, and those that are used for the RF and analog functions, consume large chip area due to the size of these elements. In addition, these elements tend to interact strongly with the active transistor RF devices from substrate coupling.
Therefore, there is a need to include such passive devices within the digital core without consuming valuable chip area and while avoiding undesirable interaction between RF components and the sensitive components within the digital core. The invention discussed below addresses these issues by presenting a novel structure and method to form the same. The conventional design uses metal conductors to fabricate such passive components. These are limited by thickness of the chip technology and occupy valuable chip area. Then placing passive components on top of the chip save chip area, make them larger in size and places far away from the device components on the chip thereby reducing interference and allowing better isolation. | {
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The invention relates to compositions, methods, and apparatuses for improving treatment and inhibition of scale in various industrial process streams, in particular certain surfactant based small molecules that have been found to be particularly effective in treating aluminosilicate scale in a Bayer process stream.
As described among other places in U.S. Pat. No. 6,814,873 the contents of which are incorporated by reference in their entirety, the Bayer process is used to manufacture alumina from Bauxite ore. The process uses caustic solution to extract soluble alumina values from the bauxite. After dissolution of the alumina values from the bauxite and removal of insoluble waste material from the process stream the soluble alumina is precipitated as solid alumina trihydrate. The remaining caustic solution known as “liquor” and/or “spent liquor” is then recycled back to earlier stages in the process and is used to treat fresh bauxite. It thus forms a fluid circuit. For the purposes of this application, this description defines the term “liquor”. The recycling of liquor within the fluid circuit however has its own complexities.
Bauxite often contains silica in various forms and amounts. Some of the silica is unreactive so it does not dissolve and remains as solid material within the Bayer circuit. Other forms of silica (for example clays) are reactive and dissolve in caustic when added into Bayer process liquors, thus increasing the silica concentration in the liquor. As liquor flows repeatedly through the circuit of the Bayer process, the concentration of silica in the liquor further increases, eventually to a point where it reacts with aluminum and soda to form insoluble aluminosilicate particles. Aluminosilicate solid is observed in at least two forms, sodalite and cancrinite. These and other forms of aluminosilicate are commonly referred to, and for the purposes of this application define, the terms “desilication product” or “DSP”.
DSP can have a formula of 3(Na2O.Al2O3.2SiO2.0-2H2O).2NaX where X represents OH−, Cl−, CO32−, SO42−. Because DSP has an inverse solubility (precipitation increases at higher temperatures) and it can precipitate as fine scales of hard insoluble crystalline solids, its accumulation in Bayer process equipment is problematic. As DSP accumulates in Bayer process pipes, vessels, heat transfer equipment, and other process equipment, it forms flow bottlenecks and obstructions and can adversely affect liquor throughput. In addition because of its thermal conductivity properties, DSP scales on heat exchanger surfaces reduce the efficiency of heat exchangers.
These adverse effects are typically managed through a descaling regime, which involves process equipment being taken off line and the scale being physically or chemically treated and removed. A consequence of this type of regime is significant and regular periods of down-time for critical equipment. Additionally as part of the descaling process the use of hazardous concentrated acids such as sulfuric acid are often employed and this constitutes an undesirable safety hazard.
Another way Bayer process operators manage the buildup of silica concentration in the liquor is to deliberately precipitate DSP as free crystals rather than as scale. Typically a “desilication” step in the Bayer process is used to reduce the concentration of silica in solution by precipitation of silica as DSP, as a free precipitate. While such desilication reduces the overall silica concentration within the liquor, total elimination of all silica from solution is impractical and changing process conditions within various parts of the circuit (for example within heat exchangers) can lead to changes in the solubility of DSP, resulting in consequent precipitation as scale.
Previous attempts at controlling and/or reducing DSP scale in the Bayer process have included adding polymer materials containing three alkyloxy groups bonded to one silicon atom as described in U.S. Pat. No. 6,814,873 B2, US published applications 2004/0162406 A1, 2004/0011744 A1, 2005/0010008 A2, international published application WO 2008/045677 A1, and published article Max HTTM Sodalite Scale Inhibitor: Plant Experience and Impact on the Process, by Donald Spitzer et. al., Pages 57-62, Light Metals 2008, (2008) all of whose contents are incorporated by reference in their entirety.
Manufacturing and use of these trialkoxysilane-grafted polymers however can involve unwanted degrees of viscosity, making handling and dispersion of the polymer through the Bayer process liquor problematic. Other previous attempts to address foulant buildup are described in U.S. Pat. Nos. 5,650,072 and 5,314,626 both of which are incorporated by reference in their entirety.
Thus while a range of methods are available to Bayer process operators to manage and control DSP scale formation, there is a clear need for, and utility in, an improved method of preventing or reducing DSP scale formation on Bayer process equipment. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists. | {
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The present invention relates to examples of a driver monitoring apparatus and method for disabling a driver facing camera. A driver facing camera may be mounted in the cab of the vehicle to monitor the driver and/or passengers. Generally, the camera is powered on as soon as the vehicle is powered on and stays on as long as the driver monitoring system to which it is connected is also powered on. This action requires tremendous amounts of video storage capability. In addition, having the video camera on while the vehicle is powered may also cause driver privacy issues, especially to drivers of commercial vehicles who leave the vehicles powered on even during mandatory rest breaks. There is a need for a sensible manner in which to keep driver facing cameras on to capture driver behavior, but allow the driver some autonomy to disable the camera when he or she is not actually driving the vehicle. | {
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1. Field of the Invention
The present invention relates to a power apparatus, and particularly to a power apparatus comprising a plurality of interconnected identifiable components defining a network. The present invention also relates to a method of locating a fault or other abnormality (hereinafter referred to generally as a "fault") in such a power apparatus.
2. Summary of the Prior Art
It is known to form a power apparatus by supporting one or more high voltage conductors in a casing of e.g. a metal, and filling that casing with insulating gas. The gas may be, for example, SF.sub.6. Such a power apparatus is used, for example, in a power sub-station for electricity transmission.
The casing forms a network, and within this network it is possible to identify a plurality of interconnected components. The network will have a large number of relatively straight casing sections, but will also normally have insulation spacers, T-junctions, disconnecting switches, circuit breakers and other items of the power apparatus which are necessary for its function. Of course, since the components form a network, the separation of the identifiable components discussed above may not correspond to physical divisions, since, e.g., a T-junction may be integrally connected to the straight sections of the casing leading from the junction, but nevertheless such a T-junction is identifiable as such, and thus the components are identifiable within the network.
Although great care is taken in the construction of such a power apparatus, it is possible for an abnormality to occur in the insulation within the apparatus, and insulation breakdown could lead to a serious accident. Therefore, it is necessary to identify the site of a potential breakdown as early as possible, and with high precision.
When a fault begins to develop in the insulation in such a network, sound waves are generated, and it is possible to arrange a plurality of sound detectors within the network, to detect the sounds generated by a fault. An example of such an arrangement was disclosed in the article entitled "Development of Compact 500 kV 8000A Gas Insulated Transmission Line-Dust Control During Field Jointing and Method for Detecting Conductive Particles" by K. Kaminaga et al in Paper 87 WM003-7 from the IEEE.
It is also known that a fault developing in such a network generates vibration waves, and again it is possible to provide vibration detectors to detect these waves.
Finally, it is known that the development of a fault generates electromagnetic waves, and JP-A-1-287475 and equivalents thereof disclosed the use of such electromagnetic waves for fault location. | {
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1. Field of the Invention
The present invention relates to a speech detection method, and more particularly to a speech distinction method that effectively determines speech and non-speech (e.g., noise) sections in an input voice signal including both speech and noise data.
2. Description of the Background Art
A previous study indicates a typical phone conversation between two people includes about 40% of speech and 60% of silence. During the silence period, noise data is transmitted. Further, the noise data may be coded at a lower bit rate than for speech data using Comfort Noise Generation (CNG) techniques. Coding an input voice signal (which includes noise and speech data) at different coding rates is referred to as variable-rate coding. In addition, variable-rate speech coding is commonly used in wireless telephone communications. To effectively perform variable-rate speech coding, a speech section and a noise section are determined using a voice activity detector (VAD).
In the standard G.729 released by the Telecommunication Standardization Sector of the International Telecommunications Union (ITU-T), parameters such as a line spectral density (LSF), a full band energy (Ef), a low band energy (El), a zero crossing rate (ZC), etc. of the input signal are obtained. A spectral distortion (ΔS) of the signal is also obtained. Then, the obtained values are compared with specific constants that have been previously determined by experimental results to determine whether a particular section of the input signal is a speech section or a noise section.
In addition, in the GSM (Global System for Mobile communication) network, when a voice signal is input (including noise and speech), a noise spectrum is estimated, a noise suppression filter is constructed using the estimated spectrum, and the input voice signal is passed through noise suppression filter. Then, the energy of the signal is calculated, and the calculated energy is compared to a preset threshold to determine whether a particular section is a speech section or a noise section.
The above-noted methods require a variety of different parameters, and determine whether the particular section of the input signal is a speech section or noise section based on previously determined empirical data, namely, past data. However, the characteristics of speech are very different for each particular person. For example, the characteristics of speech for people at different ages, whether a person is a male or female, etc. change the characteristic of speech. Thus, because the VAD uses the previously determined empirical data, the VAD does not provide an optimum speech analysis performance.
Another speech analysis method to improve on the empirical method uses probability theories to determine whether a particular section of an input signal is a speech section. However, this method is also disadvantageous because it does not consider the different characteristics of noises, which have various spectrums based on any one particular conversation. | {
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This application relates to methods for searching digital information such as computer databases and digital documents.
Digital information is widely used in various applications that use computers or microprocessors. Examples of digital information include computer files, computer databases, web pages, and electronic mails. One of many advantageous features of digital information is that digital information by nature is searchable by using computer search software tools based on various algorithms. However, one notable challenge in such computer search is to provide a thorough, relevant search without distracting a user with irrelevant information. Various web search engines are specific examples of such computer search software tools that are designed to search web pages published on web sites on the World Wide Web. | {
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Mobile, wireless electronic devices such as mobile telephones, personal digital assistants, and Global Positioning System (GPS) devices, have become very popular, and their use has become very common. It is common for one person to use two or more of these devices. These mobile devices are a subset of a group of devices that are sometimes called “pervasive computing” devices. The term “pervasive computing” is used because systems with microprocessors are now found in an array of devices that previously were largely untouched by computer technology.
These pervasive computing devices include mobile devices such as cell phones and automobile components. Pervasive computing devices often include a microprocessor and associated volatile and non-volatile memory, input means, output means, and interfaces, such as a network interface or modem, providing a link to other computing devices.
These pervasive computing devices are information handling systems, designed to give independent computing power to a single user, or a group of users in the case of networked pervasive computing devices. Pervasive computing devices may also include one or more input/output devices which are coupled to the microprocessor and which perform specialized functions (e.g. modems, sound and video devices, or specialized communication devices). Pervasive computing devices are often linked to computing systems and other pervasive computing devices using a network, such as a local area network (LAN), wide area network (WAN), or the Internet.
Satellite-based or network-based positioning technologies make it possible to determine the geographic location of mobile pervasive computing devices (e.g. location-based services for users of mobile telephones use such positioning technologies). One problem is that location information from one source may be inconsistent with information from another source. For example, a husband and wife may share a tracking device that is embedded in their car. In addition, the husband may have a location-aware mobile phone. The wife may use the car to drive to the wife's office, after giving the husband a ride to his office. Then information from the mobile phone, indicating that the husband is at his office, will be inconsistent with information from the tracking device in the car, indicating that the husband is at the wife's office.
Such an inconsistency could cause significant, practical problems. To continue the example, the husband's employer may use location information from employees' mobile electronic devices to determine the employees' location. This system would help the employer make good decisions about dispatching employees to make sales calls or service calls. However, this system could be defeated when information from one source indicates that the husband is at his office, and information from another source indicates that the husband is at the wife's office.
The inconsistency would be difficult to resolve, without additional information about the people involved, their schedules, and how they are associated with various mobile devices. To make the best use of these positioning technologies, it would be important to make use of all available information, from multiple sources, to determine users' locations. Thus there is a need for methods and systems that acquire, aggregate, and evaluate location information from multiple sources. There is a need for methods and systems that go beyond just locating a mobile device, to also include information about people, their schedules, and their various devices. | {
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The present invention relates to integrated circuits, and more particularly, to a pilot-sensor style power output of an integrated circuit.
Often, a high-power output from an integrated circuit (IC) must have a fail-safe current limiting function built-in to the device to prevent damage either to the IC or the load which it must drive. There are two conventional methods to sense the current through the IC driver output. The simpler method uses an explicit or parasitic resistance in the current path. This resistance, which must be predictable, causes a voltage drop which can be compared to a reference voltage. This voltage drop across the sense resistance is usually undesirable because it reduces the output voltage swing and generates on-chip power waste.
The second method introduces no series voltage drop in the output path, but instead builds a parallel, sense field effect transistor (FET), also known as a pilot device, which runs at a known reference current level. This pilot device is matched exactly to the driver, except the pilot device is scaled down significantly in size and in current from the driver. In this way, the pilot and the driver will be running the same current densities at the trip-point for the limiter (the maximum driver current).
U.S. Pat. No. 4,553,084 to Wrathall describes a current sensing circuit incorporating a pilot sense transistor having a sensing resistor in its source leg. The pilot sense transistor is a portion of a large switching transistor and so variations in the large switching transistor can be accurately tracked by the pilot sense transistor. An operational amplifier monitors the signal provided by the sensing resistor for providing feedback information to a driver circuit. Wrathall describes another apparatus for sensing load current in U.S. Pat. No. 4,820,968 which uses a sense resistor in the leg of a current mirroring transistor to convert a mirrored current into a voltage. This voltage is then compared to a reference voltage generated by a reference current which is a equal to a portion of the load current.
In a conventional integrated circuit with a pilot-sensor style power output, an amplifier/comparator would typically be provided for comparing the output voltage of the driver with the reference current from the pilot device. Typical approaches are complex, include transistor offset errors, and consume too much power.
In view of the foregoing background, it is therefore an object of the invention to provide current limiting in a power driving device of an integrated circuit with reduced offset errors and reduced power consumption.
This and other objects, features and advantages in accordance with the present invention are provided by an integrated circuit including a power driving device for generating an output voltage, a pilot device for sensing current through the power driving device and generating a reference voltage, and an amplifier circuit for comparing the reference voltage of the pilot device with the output voltage of the power driving device. The amplifier circuit includes a differential pair of bipolar junction transistors (BJTs) having a common base.
A first BJT of the differential pair may be diode-connected. Furthermore, the power driving device is preferably a power field effect transistor (FET), and the pilot device is preferably a sense FET scaled and matched to the power FET. The amplifier circuit may also include a first current source connected to a collector of a first BJT of the differential pair, and a second current source connected to a collector of a second BJT of the differential pair. Also, a pilot current source may be connected to a source of the sense FET, and a current sink may be connected in parallel with the pilot current source to subtract a bias current run through the first BJT from the first current source.
Also, an emitter of the first BJT may be connected to the source of the sense FET, and an emitter of the second BJT may be connected to a source of the power FET. The collector of the second BJT is connected to the gates of the sense FET and power FET, and the amplifier circuit generates a control signal for the power driving device and the pilot device.
Objects, features and advantages in accordance with the present invention are provided by a method of limiting the current in a power driving device of an integrated circuit. The method including sensing current through the power driving device with a pilot device and generating a reference voltage, and comparing the reference voltage with an output voltage of the power driving device with an amplifier circuit comprising a differential pair of bipolar junction transistors (BJTs) having a common base. A control signal is generated for the power driving device and the pilot device based upon the comparison of the reference voltage and the output voltage. | {
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1. Field of the Invention
The present invention relates, in general, to a device and method for automatically vibrating the working members of a power construction vehicle such as power excavator and, more particularly, to an automatic vibration device and method effectively used for performing an excavating, breaking or ground hardening operation of a power construction vehicle provided with a plurality of working members such as an arm, boom and bucket.
2. Description of the Prior Art
As well known to those skilled in the art, during an excavating, breaking or ground hardening operation of a power excavator, it is possible for the bucket or breaker to be overloaded. Therefore, the control levers of an excavator are manually levered by an operator during such an excavating, breaking or ground hardening operation. However, such a manual operation is inconvenient to the operators, so that it is necessary to automatically control the hydraulic system of an excavator during such an excavating, breaking or ground hardening operation. In order to achieve the above object, the following automatic vibration devices are used in the prior art. A typical automatic vibration device automatically and repeatedly reciprocates an arm, boom or bucket cylinder, which is associated with a necessary operation, and thereby automatically vibrates an associated working member such as an arm, boom or bucket. Another typical vibration device changes the amplitude of vibration of the working members in response to an electric signal generated from the control levers, thereby being somewhat convenient to an operator who levers the control levers during an excavating or ground hardening operation of an excavator. FIG. 2 shows a typical automatic vibration device for power construction vehicles, which is disclosed in Japanese Patent Publication No. Hei. 6-99948. As shown in FIG. 2, the Japanese vibration device includes a plurality of switches: an auto-vibration switch 10, a vibration mode switch 11 and a working mode switch 12. When the auto-vibration switch 10 is turned on, signals output from the two mode switches 11 and 12 are input into a controller 9. Upon receiving the signals from the mode switches 11 and 12, the controller 9 operates the signals and outputs electric control signals to a proportional control valve. The proportional control valve thus controls an associated directional control valve in response to the current control signal from the controller 9, thereby causing the directional control valve to intermittently feed pressurized fluid from a hydraulic pump to an actuator 13. For example, the Japanese automatic vibration device may automatically reciprocate the actuator 13 thereby vibrating an associated working member while bringing the relation between the amplitude (e1) of vibration in an up-motion of the actuator 13 and the amplitude (e2) of vibration in a down-motion of the actuator 13 into e1=e2. The above vibration device also may input levering signals, corresponding to levering angles of the control levers 8, into the controller 9 which operates the levering signals. After operating the levering signal, the controller 9 outputs a current control signal in order to automatically reciprocate the actuator 13 thereby vibrating the working member while changing movement of a spool in the directional control valve and bringing the relation between the two amplitudes (e1 and e2) of vibration into e1>e2 or e1<e2.
However, the above automatic vibration device during a vibration operation exclusively changes the amplitude of vibration of a working member in response to the levering signals from the control levers 8. Thus, it is necessary to use another select switch in order to change the number of vibrations of the working member during a vibration operation.
Another problem of the above automatic vibration device resides in that it necessarily has a select switch in order to select a working member, for example, an arm, boom or bucket, to be vibrated. | {
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In digital broadcasting (such as terrestrial digital broadcasting) of standards such as the Association of Radio Industries and Businesses (ARIB), the Advanced Television System Committee (ATSC), and the Digital Video Broadcasting Project (DVB), viewers can only watch programs without watching commercials. For example, viewers can avoid watching commercials by switching to another channel only during commercial breaks. In the present business model, if viewers do not watch commercials, sponsors may stop providing funds to create TV programs. As a result, the number of good quality programs may be reduced.
Accordingly, in recent years, for example, a technology has been proposed to insert an Entitlement Control Message (ECM) including a work key (key information for descrambling) into a commercial portion that forms a transport stream (TS) transmitted by being scrambled. With such a technology, viewers are made to watch commercials at least once.
For example, in a video-on-demand (VOD) system, a method is disclosed for inserting commercial related information on a commercial while a TV program is distributed. In this method, a user terminal stores a TV program in a storage unit and also stores commercial related information in the storage unit. When a commercial is being skipped, the user terminal reads out the commercial related information from the storage unit and displays the information with the program.
However, in the conventional technologies described above, viewers are not made to watch information on commercials, if the channel is switched to another channel only during commercial breaks. More specifically, in digital broadcasting, for example, if the channel is switched to another channel in real time only during commercial breaks, the commercials are not played back on the receiver side. If the channel is switched to another channel in real time, the commercial related information inserted into commercials or a TV program is not be stored in the storage unit. Accordingly, the problems described above cannot be solved by conventional technologies.
In the technology described above in which an ECM including a work key is inserted into the TS to be transmitted, it is assumed that the broadcast data is transmitted by being scrambled. Accordingly, it is not applicable when the broadcast data is transmitted without being scrambled. Patent Document 1: Japanese Laid-open Patent Publication No. 2002-51321 Patent Document 2: International Publication Pamphlet No. WO 03/079690 | {
"pile_set_name": "USPTO Backgrounds"
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1. Field of the Invention
The present invention relates to a device that can be inserted into a body through a natural orifice with an endoscope or other steerable guide member. The present invention may be used in conjunction with a suturing instrument to secure an applied suture to the tissue of a mammal, whether human or not, and whether or not alive.
2. State of the Art
Natural Orifice Translumenal Endoscopic Surgery (NOTES) involves passing surgical instruments in association with an endoscopic camera through a natural orifice, such as the mouth, vagina, or anus, to a desired organ. By avoiding major incisions through the skin, muscle, and nerves of the abdomen, patients may experience a quicker recovery with less pain and scarring while further reducing the post-operative risk of surgery.
In co-owned US Pub. No. 20090312775A1, an endoscopic suturing device suitable for use in a NOTES procedure is described. The device has a structure with a sufficiently small distal profile for delivery through a natural orifice, while providing a needle movable on an arm through a large opening and closing angle and which produces a large force upon the needle for piercing tissue to perform a surgical operation such as tissue approximation and suturing. A length of suture is permanently attached to the needle and forms stitches about tissue engaged at the distal end of the device as the needle is moved through the tissue and the distal end of the device is moved relative to the tissue. After one or more stitches have been formed in the tissue, the needle is released from the device and the free end of the suture is secured relative to the tissue. In accord with one manner of securing the free end of the suture, portions of the suture may be tied together about the tissue. In accord with another manner of securing the suture, a cinch element is advanced over the suture and cinches the tissue between the needle on one side of the tissue and the cinch on the other side of the tissue. The suture is then severed.
In addition to the cinch and cinch-applying instrument described in the above-referenced publication, other cinch instruments and deployable cinches are known. For example, referring to prior art FIG. 1, also known is a cinch applicator 10 for use in deploying the two parts 12, 14 of a cinch onto suture 16 in a NOTES procedure. The applicator 10 includes an elongate flexible tubular member 18, a hypotube 20 fixed to the distal end 22 of the flexible tubular member 18, a flexible shaft 24 extending through the tubular member 18 and the hypotube 20, and a proximal handle (not shown) for moving the shaft 24 longitudinally relative to the tubular member 18. The hypotube 20 defines a distal housing 26 and a proximal lateral window 28. A slidable plunger 30 provided with a guillotine 32 is provided within the hypotube 20, with the guillotine 32 fully proximal of the housing 26 and distal of the lateral window 28.
The two-part cinch includes a collar 12 and a plug 14 engageable within the collar. The collar 12 has a cylindrical outer shape that is retained in the distal housing 26 of the hypotube 20 with a simple dimpling mating structure. The collar 12 also includes a proximal inner lip 33, and an outer lip 34 seating at the distal end of the hypotube 20 and having a flat distal facing end 35. The plug 14 of the cinch is attached to the distal end of the flexible shaft 24. The plug 14 has an enlarged distal flange 36 corresponding in size and shape to the outer lip 34 on the collar 12. The plug 14 has an elongate tubular body 38 defining a throughbore 40 in which the flexible shaft 24 extends, and a proximal circumferential exterior groove 42. A distal portion of the shaft 24 has a bend 44 to facilitate retention within the throughbore 40. The distal end of the shaft 24 has a rounded bead 46 that sits at the flange 36 of the plug. The bend 44 and the bead 46 trap the flexible shaft relative to the plug.
In operation, from outside the patient, the proximal end of the suture 16 is thread through the collar 12 and hypotube 20 and out of the lateral window 28. Then the applicator 10 is advanced through an endoscope so that the elements of the cinch are provided adjacent the stitched tissue. When the handle is operated, the shaft 24 is retracted to draw the plug 14 into an interference fit within the collar 12, with the inner lip 33 of the collar positively engaging the outer groove 42 on the plug. The suture 16 is captured between the outer surface of the plug 14 and the inner surface of the collar 12 so that the cinch is secured to the suture. Upon further retraction of the shaft 24, the shaft is pulled such that the bend 44 and bead 46 of the shaft 24 are pulled all the way through the plug 14 until released therefrom, and drawn back into engagement with the plunger 30. As the shaft 24 is moved further proximally relative to the hypotube 20, movement of the shaft 24 causes the guillotine 32 to slide past the window 28 and sever the proximal portion of the suture 16 from the portion of the suture attached to the cinch. Once the suture 16 is severed, a jerking motion is applied to the applicator 10 to release the engagement formed by the dimpling structure between to the cinch 12, 14 and applicator 10.
The applicator and cinch are thereby together capable of effectively securing stitched suture to tissue. | {
"pile_set_name": "USPTO Backgrounds"
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Vehicles, such as motorized vehicles and electric vehicles have been around for some time. Vehicles provide a means that enable humans to drive from place to place. In today's world, vehicles have become an indispensable mode of transportation, and provide the freedom to travel at any time of day and for various distances. Vehicles can be publically operated or can be privately owned. Humans most commonly operate vehicles, no matter the type, whether electric or combustion engine based.
In recent years, technology has been advancing, yet accidents occur far too often. There is a need for ways to implement technology to assist drivers to avoid or reduce accidents.
It is in this context that embodiments of the invention arise. | {
"pile_set_name": "USPTO Backgrounds"
} |
There is known a flexible circuit boards in which a stretch prevention guard which prevents stretching and contracting of a zone including an electric connector of a stretchable circuit body is provided to a non-stretchable component-mounting board in order to suppress destruction of the electric connector caused by concentration of stress between the non-stretchable component-mounting board and the stretchable circuit body (for example, refer to Patent Document 1). | {
"pile_set_name": "USPTO Backgrounds"
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Application programming interfaces (APIs) allow companies to open their resources to internal or external customers in a secure and controlled way. Within an organization, internal APIs provide updatability, flexibility, and scalability as the organizational internal APIs facilitate access to data and functionalities of the organization's backend Information Technology (IT) systems according to well-defined API access rules.
Cloud computing refers to the use of dynamically scalable computing resources accessible via a network, such as the Internet. The computing resources, often referred to as a “cloud,” provide one or more services to users. These services may be categorized according to service types, which may include, for example, applications/software, platforms, infrastructure, virtualization, and servers and data storage. The names of service types are often prepended to the phrase “as-a-Service” such that the delivery of applications/software and infrastructure, as examples, may be referred to as Software-as-a-Service (SaaS), Platform-as-a-Service (PaaS), and Infrastructure-as-a-Service (IaaS), respectively.
The term “cloud-based services” or, more simply, “cloud services” refers not only to services provided by a cloud, but also to a form of service provisioning in which cloud customers contract with cloud service providers for the online delivery of services provided by the cloud. Cloud service providers manage a public, private, or hybrid cloud to facilitate the online delivery of cloud services to one or more cloud customers. | {
"pile_set_name": "USPTO Backgrounds"
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This application relates to surgical guides and more specifically to a drill or anchor placement guide for glenoid procedures.
In certain surgical procedures it is desired to place a surgical anchor into the rim of bone which defines the outer extent of the glenoid cavity of a scapula, as for example in Bankart repairs and labral reconstructions, including superior labral anterior to posterior (SLAP) lesion repairs. The rim is somewhat narrow and to maximize holding and use of the available bone it is desired to place the anchor straight into the bone from the peak of the rim without significant off-axis variation. Current procedures employ a straight tubular cannula having a toothy distal end or a pair of jaws (sometimes called a fish mouth) formed at a distal end which are placed over the rim. Achieving proper angular alignment of the cannula to prevent off-axis anchor placement can be tricky especially in arthroscopic procedures. The trajectory of the guide is determined in large part by the initial placement of an arthroscopy cannula and by the soft tissue constraints. Curved cannulas can be used but this adds complexity to drilling and anchor passage and they can be more difficult than straight cannulas to maintain in position between drilling and anchor placement. | {
"pile_set_name": "USPTO Backgrounds"
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1. Field of the Invention
The invention relates to a discharge lamp for the disactivation of micro-organisms having an emitted radiation suitable for disactivation.
2. Prior Art
There are known discharge lamps being used for disactivation of micro-organisms in gases and fluids. In German specification No. 1 679 567 a room air purifying device is described that cleans the air by the effect of ultraviolet rays. As a source of ultraviolet rays one preferably used is a low pressure mercury burner. An electric room air deodorizing device with ultraviolet low pressure burners is disclosed in German disclosure 1 492 460.
Also, a room disinfecting device is disclosed in German registered design 7 314 612 using quartz lamps emitting an ultraviolet radiation for the formation of ozone, the wave length range of which not beng exactly given.
A device for the disinfection of water by means of immersion lamps in which a discharge lamp is being arranged, is shown in U.S. Pat. No. 3,566,105 . The discharge lamp described therein concerns likewise a mercury discharge lamp.
Although the mercury discharge lamps described in the above mentioned arrangements are emitting radiations in the wave length range between 260 to 280 nm, corresponding to the wave length range for the optimum disactivation of micro-organisms, these discharge lamps present a series of disadvantages.
When using low pressure mercury burners, the disinfection arrangements occupy a rather large volume. The reason for this can be found in the small output of emitted radiation per centimeter of discharge length. In addition thereto the emitting maximum is at 254 nm, there is the further disadvantage that the effect of this radiation corresponds only to about 80% of that one in the wave length range of 260 to 280 nm.
Low pressure discharge lamps are susceptible to variations in temperature, as they are caused, for example, by air flowing past the discharge vessels, manifesting itself by a reduced emitting capacity.
Space-saving arrangements can be made by using high pressure mercury burners which, moreover, are less susceptible to variations of temperature. These, however, are subject to the disadvantage that only a small radiation portion is emitted in the wave length range of 260 to 280 nm, yet there appears radiation in the range of 400 to 450 nm causing a re-activation of the micro-organisms. | {
"pile_set_name": "USPTO Backgrounds"
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Low bit-error-rate communication of data over a communications channel is often considered an important requirement in communications and computation systems. Fulfilling this requirement is increasingly difficult in systems with data rates exceeding multiple gigabits per second (“Gbits/s” or “Gbps”). In the case of an interface or interconnect, either between or within semiconductor chips (also known as dies) that are configured for simultaneous bi-directional communication, there is a problem associated with resource allocation. In a contemporary simultaneous bi-directional communication link, each direction is allocated an equal, fixed bandwidth. In applications such as application specific integrated circuits (ASICs) and memory systems, a required bandwidth in a respective direction on a link is usually unknown a priori and may vary as a function of time. In addition, such a fixed and equal bandwidth allocation may necessitate equal circuit complexity on both sides of the link.
In a simultaneous bi-directional link, the two directions also share a common band of frequencies. This poses an additional challenge of cross-talk between signals on the link.
Like reference numerals refer to corresponding parts throughout the drawings. | {
"pile_set_name": "USPTO Backgrounds"
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1. Field of the Invention
The invention relates to self-adhesive, thermally crosslinkable 1-component silicone compositions having a long shelf-life, to silicone elastomers obtainable therefrom, and to their use in manufacturing composite moldings.
2. Background Art
The adhesion of crosslinked silicone elastomers to numerous substrates, such as plastics, metals and glasses, is known to be low, i.e. if an addition-crosslinking silicone elastomer material is applied to a substrate and then crosslinked, the resulting silicone elastomer can, as a rule, be peeled away from the substrate surface without difficulty, i.e. by application of but slight tensile forces. Frequently, spontaneous delamination of the silicone elastomer from the substrate may occur. However, since strong and permanent adhesion of the silicone elastomer to the substrate is of decisive importance in numerous applications, a large number of special measures have been proposed for obtaining a strong bond between substrate and silicone elastomer.
In principle, the adhesive strength of the silicone elastomer/substrate laminate can be increased by suitably modifying the chemical and/or physical characteristics of the substrate or of the substrate surface prior to application of the crosslinking silicone elastomer composition. Modification can be effected, for example, by pretreating the substrate surface with adhesion-promoting additives (i.e. primers), by plasma treatment of the substrate surface, by mixing special additives into the substrate, by controlling the morphology of the substrate, by increasing the surface roughness, etc. These measures have, inter alia, the disadvantage that additional process steps are required or the characteristics of the substrate have to meet special requirements.
In the case of high temperature-crosslinking systems, the adhesive strength of the silicone elastomer/substrate composite can be increased by changing the chemical and/or physical characteristics of the addition-crosslinking silicone elastomer material in a controlled manner. Numerous adhesion-promoting additives are known which when mixed with the uncrosslinked silicone material, give rise to self-adhesion of the resulting silicone elastomer on various substrates. These include compounds which contain highly reactive functional groups, such as alkoxy, epoxy, carboxyl, amino, etc., these groups generally being chosen such that the adhesion promoter is capable of reacting both with the substrate and with a silicone elastomer constituent. Although such adhesion promoters may make it possible to dispense with pretreatment of the substrate, the adhesive strength obtained frequently is not satisfactory. Furthermore, the adhesive strength can be increased only to a limited extent by higher adhesion promoter content since the highly reactive groups contained in the adhesion promoter have an increasingly adverse effect on performance characteristics such as shelf-life, crosslinking characteristics (inhibition), toxicology, etc. For these reasons, interest tends to be focused on keeping the content of adhesion promoters as low as possible.
EP-A-686 671 describes a self-adhesive addition-crosslinking material which manages without special adhesion promoters due to the presence of unique reactive polymer constituents. The adhesion-promoting constituent is either an organohydrogenpolysiloxane with minimally two SiH groups on average and whose monovalent Si-bonded radicals consist of at least 12 mol % of hydrocarbon radicals having an aromatic ring, or is a compound with at least one SiH group on average and which contains a group consisting of two aromatic rings, the two aromatic rings being separated from one another by xe2x80x94R13R14Sixe2x80x94, xe2x80x94R13R14SiOxe2x80x94, xe2x80x94OR13R14SiOxe2x80x94 or xe2x80x94R13R14SiOR13R14Sixe2x80x94 and the radicals R13 and R14 being monovalent hydrocarbon radicals. The adhesion-promoting constituent can thus simultaneously be the crosslinking agent of the silicone elastomer material. Good adhesion to organic plastics (especially ABS) is achieved with this composition, while at the same time easy demoldability is exhibited from metallic vulcanization molds, i.e. chromium- or nickel-plated steel molds or mold produced from aluminum alloy.
The high content of 12 mol % or more of radicals containing aromatic rings in the SiH-containing, adhesion-promoting constituent of the compositions of EP-A-686 671, however, results in considerable incompatibility with the other constituents of the addition-crosslinking silicone elastomer material, leading on the one hand, to partial separation (exudation) during storage, necessitating repeated homogenization of the constituent-containing component before use. This incompatibility, which is evident simply from a milky haze in the uncrosslinked material, also manifests itself in substantially reduced transparency of the silicone elastomer parts produced therefrom. If the adhesion-promoting constituent simultaneously acts as a crosslinking agent of the silicone elastomer composition, the incompatibility leads to vulcanization disturbances which result in inhomogeneous network formation and poor mechanical vulcanization properties. In order to overcome these vulcanization disturbances, an SiH-containing crosslinking agent completely compatible with the silicone elastomer material must be used in addition to the adhesion-promoting SiH-containing constituent, which however results in other disadvantages, for example higher compression set, and higher tendency to exude the adhesion-promoting constituent. The high content of aromatic radicals in the SiH-containing, adhesion-promoting constituent also causes a considerable structural viscosity and thixotropy of the silicone elastomer material, which is undesirable in numerous applications for example in injection molding and in liquid silicone rubber. Moreover, the curable silicone mixture of EP-A-686 671 has a very limited shelf-life, so that metering of the platinum catalyst or mixing with the H-siloxane component must occur only a few minutes to hours prior to vulcanization. Finally, the adhesion of this composition to metals is also insufficient.
EP-A-875 536 describes a self-adhesive addition-crosslinking silicone rubber blend which is distinguished in that the SiH crosslinking agent contains at least 20 SiH groups, the remaining radicals being aliphatically saturated; the composition contains an epoxy-functional alkoxysilane and/or alkoxysiloxane; and further optionally a peroxide. The use of glycidyloxypropyltrimethoxysilane (Glymo) is particularly preferred. The silicone rubber blend described in EP-A-875 536 is suitable in particular for the production of composite moldings which consist of the silicone elastomer and an organic plastic. However, the composition described in EP-A-875 536 has the disadvantage that sufficient adhesive strength can be achieved only with the use of very Si-rich crosslinking agents having on average at least 20 SiH groups per molecule. For instance, the crosslinking agents exemplified in the examples have 30 SiH groups per molecule. The use of such high-functionality crosslinking agents reduces the shelf-life of addition-crosslinking silicone rubber blends considerably, i.e. the flowability is greatly impaired, which can lead to stiffening of the material. As a result, proper processing of the material, for example by injection molding, is no longer possible. In addition, relatively large amounts of epoxy-functional alkoxysilane/alkoxysiloxane have to be used in order to achieve a high adhesive strength, with the result that the crosslinking rate is considerably reduced. Although this can partly be compensated by employing a peroxide, as described in EP-A-875 536, only peroxides having a low initiation temperature, such as the disclosed 2,4-dichlorobenzyl peroxide, are suitable for this purpose owing to the necessarily low crosslinking temperature (softening of the organic plastic). These peroxides are both toxicologically suspect owing to the cleavage and secondary products liberated (PCB problems), and further adversely affect the shelf-life of the material. Moreover, these blends can be stored for only a relatively short time, with pot lives in the range of minutes, so that no 1-component products for processing by composite producers can be made available therefrom, but only 2-component or A/B systems.
In the case of addition-crosslinking silicone materials, however, 2-component systems are associated with numerous disadvantages, for example, complicated logistics and a high danger of contamination, in particular of the platinum component or of A/B components with one another, so that partial crosslinking may inadvertently occur during storage. Moreover, an additional step for mixing A and B components is required, which leads to a very sensitive intermediate. This necessitates immediate processing and frequent cleaning of the metering plants, mixing and processing machines, etc., since the material remaining as a result of back-mixing or adhesion to surfaces gels relatively rapidly.
EP-A-1 041 117 describes a readily adhering addition crosslinkable 1-component silicone elastomer composition which contains an organopolysiloxane having both SiH and alkenyl groups and a compound having both alkenyl and hydroxyphenyl groups in the same molecule. The preparation of such silicone elastomer compositions is very complicated and therefore not economical. Moreover, this 1-component blend, too, does not have a long shelf-life but has to be processed rapidly after addition of the platinum catalysts described. It thus also has disadvantages in terms of logistics and cleaning, as in the case of A/B systems.
EP-A-1 045 006 discloses improvement of adhesion in highly viscous, peroxide-crosslinkable silicone elastomer materials (HTV), wherein silatrane derivatives, for example silatrane derivatives of a mixture 2-hydroxyethylamine, methyltrimethoxysilane, and allyl glycidyl ether, are added to the silicone rubber blend in order to obtain good adhesion to organic resins such as PBT or FPP, during vulcanization. Such additives are, however, toxicologically unsafe, both during incorporation in the plant and during the production and use of the composite, since they can release aggressive cleavage products.
In summary, it may be stated that none of the conventional addition-crosslinking silicone elastomer compositions satisfactorily meet the requirements set for a self-adhesive silicone elastomer material which is to be used in particular for the production of composite moldings or for the encapsulation of electrical/electronic parts, namely:
a) good processibility and shelf-life,
b) high crosslinking rate at relatively low temperatures,
c) high adhesive strength on organic plastics, metals and glasses,
d) easy demoldability from vulcanization molds,
e) toxicological safety, and
f) high level of performance characteristics, i.e. transparency, noncorrosiveness, good mechanical and/or electrical property profiles.
It would be desirable to provide a heat-crosslinkable 1-component silicone elastomer material which has good self-adhesion to organic plastics, metals and glasses, which does not have the disadvantages discussed previously and which meet the above requirements.
The invention pertains to self-adhesive, thermally crosslinkable, 1-component silicone compositions comprising an alkenyl-functional diorganopolysiloxane (A), a specific filler or mixture of fillers (B), an SiH-functional organohydrogenpolysiloxane (C), a hydrosilylation catalyst or peroxide crosslinking agent (E), and an organosilicon compound (D) bearing two different functional groups, one group being a vinyl radical or an epoxy or (meth)acryloyloxy group, and one group being a hydrolyzable group.
Diorganopolysiloxane (A) comprises the general formula (1)
R1aR2bSiO(4xe2x88x92axe2x88x92b)/2xe2x80x83xe2x80x83(1),
in which
R1 is a hydroxyl radical or a monovalent, optionally halogen-substituted C1-20 hydrocarbon radical optionally containing O, N, S or P atoms, and being free of aliphatically unsaturated groups,
R2 is a monovalent, aliphatically unsaturated, optionally halogen-substituted C2-10 hydrocarbon radical optionally containing O, N, S or P atoms,
b denotes values from 0.003 to 2,
with the proviso that 1.5 less than (a+b) less than 3.0, that on average at least two aliphatically unsaturated radicals R2 are present per molecule and that the viscosity of the diorganopolysiloxane (A), determined at 25xc2x0 C., is at least 100 Pa.s,
(B) a filler which is selected from filler (B1) having a specific surface area of at least 50 m2/g, aluminum hydroxide (B2), and mixtures thereof,
(C) an organohydrogenpolysiloxane of the general formula (2)
R3cR4dR5eHfSiO(4xe2x88x92cxe2x88x92dxe2x88x9223xe2x88x92f)/2xe2x80x83xe2x80x83(2),
in which
R3 is a monovalent aliphatically saturated C1-20 hydrocarbon radical,
R4 is (a) an optionally halogen-substituted monovalent C6-15 hydrocarbon radical which contains at least one aromatic C6-ring, or (b) a halogen-substituted, saturated monovalent C2-20 hydrocarbon radical optionally containing O, N, S or P atoms,
R5 is a bivalent, optionally halogen-substituted C6-20 hydrocarbon radical Si-bonded at both ends, optionally containing O, N, S or P atoms,
e denotes 0 or a positive integer,
c, d, and f denote positive numbers, with the proviso that the organohydrogenpolysiloxane (B) contains on average 3 to less than 20 SiH groups per molecule, that the relationship: 0.05 less than 100 (d+e)/(c+d+e+f) less than 12 is fulfilled, and that the viscosity of the organohydrogenpolysiloxane (B), determined at 25xc2x0 C., is 1 mPa.s to 100 Pa.s,
(D) an organosilicon compound of the general formula (3)
R7gR8hR9iSiO(4xe2x88x92gxe2x88x92hxe2x88x92i)/2xe2x80x83xe2x80x83(3)
and/or its partial hydrolysis products, in which
R7 is a hydrogen radical, a hydroxyl radical or an optionally halogen- or cyano-substituted, monovalent saturated C1-20 hydrocarbon radical optionally containing O, N, S or P atoms,
R8 is a vinyl radical or an optionally halogen-substituted monovalent C2-20 hydrocarbon radical containing at least one epoxy group or substituted by at least one acryloyloxy or methacryloyloxy group, optionally containing O, N, S or P atoms,
R9 is a hydrolyzable monovalent optionally halogen-substituted C1-20 hydrocarbon radical bonded to Si via an Sixe2x80x94Oxe2x80x94Cxe2x80x94, Sixe2x80x94Oxe2x80x94Nxe2x80x94 or Sixe2x80x94N-link, optionally containing O, N, S or P atoms, with the proviso that 4 greater than gxe2x89xa70, 4 greater than h greater than 0, 4 greater than i greater than 0, 4xe2x89xa7(h+1) greater than 0 and 4xe2x89xa7(g+h+i), and
(E) a hydrosilylation catalyst or peroxide crosslinking agent,
the Mooney viscosity of the silicone compositions, determined at 25xc2x0 C. according to DIN 53523 Part 3, being 20 to 200.
In the silicone compositions, organohydrogenpolysiloxane (C) acts as an adhesion promoter and, in the case of addition-crosslinkable silicone compositions, simultaneously as a crosslinking agent.
The advantageous properties of the silicone compositions consist in the fact that the self-adhesion after vulcanization is achieved by a constituent contained in every addition-crosslinking material, namely the SiH-containing crosslinking agent (C), in combination with the organosilicon compound (D) having epoxy-, acryloyloxy-, methacryloyloxy- and/or vinyl-functional and hydrolyzable radicals, it merely being necessary for the SiH crosslinking agent (C) to contain a few groups which reduce the compatibility with the other constituents of the material (especially with the diorganopolysiloxane (A)). These latter groups are not reactive functional groups but are preferably inert phenyl groups, with the result that the toxicological safety of the material (e.g. drinking water approval; BGA/FDA approval) is preserved, no vulcanization problems occur, the shelf-life is sufficient, the transparency or translucency of the crosslinked silicone elastomer is maintained, and no constituents which exude or are extractable are added. The combination of the SiH crosslinking agent (C), having reduced compatibility, with an organosilicon compound (D) having epoxy-, vinyl-, acryloyloxy- and/or methacryloyloxy-functional and hydrolyzable radicals, makes it possible, first, to keep the content of incompatible groups in the SiH crosslinking agent low, and secondly, to achieve the adhesion-promoting activity of the organosilicon compound (D) having epoxy-, vinyl-, acryloyloxy- and/or methacryloyloxy-functional and hydrolyzable radicals, even in the case of relatively low SiH functionality of the SiH crosslinking agent. Only the combination of the two constituents (C) and (D) leads to synergistic self-adhesion effects of these two constituents.
In particular, the present composition is distinguished by the fact that
a) the crosslinking rate is scarcely reduced,
b) the transparency or color of the crosslinked silicone elastomers is not impaired,
c) there is no need to accept any disadvantageous changes in the mechanical elastomer properties,
d) the adhesion-promoting constituent (C) in the case of addition-crosslinkable composition simultaneously acts as a crosslinking agent (no additional SiH crosslinking agent required),
e) strong self-adhesion can be achieved even on metals without hindering the demoldability from metal vulcanization molds, i.e. adhesion to metal shortly after crosslinking permits demolding of the silicone elastomer part whereas if the adhesively bonded silicone elastomer/metal composite is stored, the silicone elastomer becomes strongly and permanently adhered onto the metal surface within a short time, and
f) the flowability or processibility of the uncrosslinked material is minimally impaired.
Although the adhesion-promoting constituent (C) of the present invention also has reduced compatibility with the other constituents of the material, which is evident from turbidity upon mixing, this turbidity disappears completely as soon as the material is heated for the purpose of crosslinking, indicating a homogeneous distribution of the molecules throughout the crosslinking agent in the material at the time of crosslinking.
If the adhesion-promoting SiH-containing constituent (C) contains phenyl groups in at least 12 mol % of the radicals, however, this turbidity also persists at customary crosslinking temperatures and indicates inhomogeneous network formation, which can also be demonstrated on the basis of the optical properties, the crosslinking characteristics and the mechanical properties.
Examples of the radicals R1 are alkyl radicals such as the methyl, ethyl, propyl, isopropyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-octyl, 2-ethylhexyl, 2,2,4-trimethylpentyl, n-nonyl and octadecyl radicals; cycloalkyl radicals such as the cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, adamantylethyl or bornyl radicals; aryl or alkaryl radicals such as the phenyl, ethylphenyl, tolyl, xylyl, mesityl or naphthyl radicals; aralkyl radicals such as the benzyl, 2-phenylpropyl or phenylethyl radicals, and derivatives of the above radicals which are halogenated and/or functionalized with organic groups such as the 3,3,3-trifluoropropyl, 3-iodopropyl, 3-isocyanatopropyl, aminopropyl, methacryloyloxymethyl or cyanoethyl radicals. Preferred radicals R1 contain 1 to 10 carbon atoms and optionally halogen substituents. Particularly preferred radicals R1 are the methyl, phenyl and 3,3,3-trifluoropropyl radicals, in particular the methyl radical.
The radicals R2 are reactive in a hydrosilylation reaction. Examples of these are alkenyl and alkynyl radicals, such as the vinyl, allyl, isopropenyl, 3-butenyl, 2,4-pentadienyl, butadienyl, 5-hexenyl, undecenyl, ethynyl, propynyl and hexynyl radical; cycloalkenyl radicals, such as the cyclopentenyl, cyclohexenyl, 3-cyclohexenylethyl, 5-bicycloheptenyl, norbornenyl, 4-cyclooctenyl or cyclooctadienyl radical; alkenyl aryl radicals, such as the styryl or styrylethyl radical, and derivatives of the above radicals which are halogenated and/or contain heteroatoms, such as the 2-bromovinyl, 3-bromo-1-propynyl, 1-chloro-2-methylallyl, 2-(chloromethyl)allyl, styryloxy, allyloxypropyl, 1-methoxyvinyl, cyclopentenyloxy, 3-cyclohexenyloxy, acryloyl, acryloyloxy, methacryloyl or methacryloyloxy radicals. Preferred radicals R2 are the vinyl, allyl and 5-hexenyl radicals, in particular the vinyl radical.
In the case of the diorganopolysiloxanes (A) of the general formula (1), the viscosity determined at 25xc2x0 C. is preferably at least 1,000 Pa.s, more preferably at least 10,000 Pa.s, preferably not more than 1,000,000 Pa.s, and more preferably not more than 100,000 Pa.s.
Filler (B) is incorporated into the silicone composition in order to achieve a sufficiently high mechanical and/or electrical strength of the crosslinked silicone rubber. Filler (B1) having a specific surface area of at least 50 m2/g, in particular 100 to 400 m2/g, determinated by the BET method, has an active reinforcing effect. The actively reinforcing fillers (B1) are preferably precipitated and/or pyrogenic silica. Filler (B2) is aluminum hydroxide, which is also referred to as alumina trihydrate, preferably having a specific surface area of at least 2 m2/g, in particular 3 to 50 m2/g, according to the determination by the BET method.
Aluminum hydroxide (B2) having a particle size of 0.1 to 50 xcexcm, preferably 1 to 30 xcexcm, is preferably used and improves the electrical insulation properties and the flammability. The aluminum hydroxide (B2) may be untreated or surface-treated with vinylsilanes, such as, for example, Martinal(copyright) 104S from ALUSUISSE, Martinswerk S. A. and Hymod(copyright) 632 or 632 SP from Huber, USA.
The silanization of aluminum hydroxide (B2) can also be carried out during the preparation of the mixture itself, by first introducing the untreated aluminum hydroxide (B2) into the diorganopolysiloxane (A) and then metering in preferably 0.1 to 3% by weight, in particular 0.2 to 2% by weight, based on untreated aluminum hydroxide (B2) of a hydrolyzable vinyl compound, such as vinyltriethoxy- or vinyltrimethoxysilane or divinyltetramethyldisilazane, preferably at 50 to 150xc2x0 C. Corresponding amounts of difunctional vinyl compounds, such as methylvinyldialkoxysilanes or short-chain SiOH-rich vinylmethylsiloxanes, which can be prepared via an upstream hydrolysis of a methylvinylsilane, are also suitable.
The viscosity of the mixture of diorganopolysiloxane (A) and filler (B) is preferably at least 40,000 Pa.s, more preferably at least 80,000 Pa.s.
Examples of R3 are alkyl radicals such as the methyl, ethyl, propyl, isopropyl, tert-butyl, n-octyl, 2-ethyhexyl and octadecyl radicals, and cycloalkyl radicals such as the cyclopentyl, cyclohexyl, norbornyl or bornyl radicals. Preferred radicals R3 are hydrocarbon radicals having 1 to 10 carbon atoms. A particularly preferred radical R3 is the methyl radical.
Examples of R4 (a) are the phenyl, tolyl, xylyl, biphenylyl, anthryl, indenyl, phenanthryl, naphthyl, benzyl, phenylethyl or phenylpropyl radicals, and derivatives of the above radicals which are halogenated and/or functionalized with organic groups, such as the o-, m- or p-chlorophenyl, pentafluorophenyl, bromotolyl, trifluorotolyl, phenoxy, benzyloxy, benzyloxyethyl, benzoyl, benzoyloxy, p-tert-butylphenoxypropyl, 4-nitrophenyl, quinolyl or pentafluorobenzoyloxy radicals.
Examples of hydrocarbon radicals R4 (b) having 2 to 20 carbon atoms are the 3-chloropropyl, 3-bromopropyl, 3,3,3-trifluoropropyl, 2-fluoroethyl, 1,1-dihydroperfluorododecyl and 2-cyanoethyl radicals. Particularly preferred radicals R4 are the phenyl radical and the 3,3,3-trifluoropropyl radical.
Preferred radicals R5 correspond to the general formula (4)
xe2x80x94(O)sxe2x80x94(R6)txe2x80x94(O)uxe2x80x94(X)wxe2x80x94(O)uxe2x80x94(R6)txe2x80x94(O)sxe2x80x94xe2x80x83xe2x80x83(4)
in which
s, t, u and w, independently of one another, denote the values 0, 1 or 2,
R6 may be identical or different and denote a bivalent, optionally halogen-substituted hydrocarbon radical which optionally contains O, N, S or P atoms, is free of aliphatically unsaturated groups and contains 1 to 10 carbon atoms, such as xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94, xe2x80x94CF2xe2x80x94, xe2x80x94CH2xe2x80x94CF2xe2x80x94, xe2x80x94CH2xe2x80x94CHxe2x80x94(CH3)xe2x80x94, xe2x80x94C(CH3)2xe2x80x94, xe2x80x94CH2xe2x80x94C(CH3)2xe2x80x94, xe2x80x94C(CH3)2, xe2x80x94CH2xe2x80x94CH2xe2x80x94CHxe2x80x94Oxe2x80x94xe2x80x94CF2xe2x80x94CF2xe2x80x94Oxe2x80x94,
xe2x80x94(X)xe2x80x94 denotes a bivalent radical which is selected from xe2x80x94Phxe2x80x94, xe2x80x94Phxe2x80x94Oxe2x80x94Phxe2x80x94, xe2x80x94Phxe2x80x94Sxe2x80x94Phxe2x80x94, xe2x80x94Phxe2x80x94SO2xe2x80x94Phxe2x80x94, xe2x80x94Phxe2x80x94C(CH3)2xe2x80x94Phxe2x80x94, xe2x80x94PhC(CF3)2xe2x80x94Phxe2x80x94, xe2x80x94Phxe2x80x94C(O)xe2x80x94Phxe2x80x94, cyclohexylene or norbornylene, xe2x80x94Phxe2x80x94 designating a phenylene group. A particularly preferred radical R5 is the phenylene radical.
The organohydrogenpolysiloxane (C) preferably contains 5 to 18 SiH groups per molecule. The viscosity of the constituent (C), measured at 25xc2x0 C., is preferably 2 mPa.s to 1 Pa.s. Owing to the labile nature of the SiH group, the constituent (C) may have a low content, typically less than 100 ppm by weight, of Si-bonded OH groups, arising from the preparation.
Examples of the hydrocarbon radicals R7 are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-octyl, 2-ethylhexyl, 2,2,4-trimethylpentyl, n-nonyl and octadecyl radicals; cycloalkyl radicals such as the cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, adamantylethyl or bornyl radicals; aryl radicals such as the phenyl, ethylphenyl, tolyl, xylyl, mesityl or naphthyl radicals; aralkyl radicals such as the benzyl, phenylethyl or phenylpropyl radicals; alkenyl or alkynyl radicals such as the vinyl, allyl, isopropenyl, 3-butenyl, 2,4-pentadienyl, butadienyl, 5-hexenyl, undecenyl, ethynyl, propynyl and hexynyl radicals; cycloalkenyl radicals such as the cyclopentenyl, cyclohexenyl, 3-cyclohexenylethyl, 5-bicycloheptenyl, norbornenyl, 4-cyclooctenyl or cyclooctadienyl radicals; aralkenyl radicals such as the phenylethenyl and phenylethynyl radical; and derivatives of the above radicals which are halogen-substituted and/or contain heteroatoms, such as the 3-chloropropyl, 3-bromopropyl, decafluoro-1,1,2,2-tetrahydrooctyl, (p-chloromethyl)phenyl, (p-chloromethyl)phenethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, 2-bromovinyl, 2-allyloxymethyl, acetyl, acetoxymethyl, acetoxyethyl, acetoxypropyl, 3-phenoxypropyl, benzoyloxypropyl, mercaptopropyl, cyanoethyl, cyanopropyl, 3-cyanobutyl, 3-isocyanatopropyl, 2-(carbomethoxy)ethyl, 10-(carbomethoxy)decyl, 2-(carboxymethylthio)ethyl, 3-carboxypropyl, aminomethyl, aminoethyl, aminopropyl, aminohexyl, aminoethylaminopropyl, 3-(N-allylamino)propyl, (aminoethylaminomethyl)phenethyl, m-aminophenyl, 3-(m-aminophenoxy)propyl, 3-acryloyoxypropyl, 3-acryloyloxy-2-hydroxypropyl, 4-(acryloyloxymethyl)phenethyl, methacryloyloxymethyl, methacryloyloxyethyl and methacryloyloxypropyl radicals. Preferred radicals R7 are the methyl, ethyl, propyl, butyl, octyl, vinyl, allyl, phenyl, 3,3,3-trifluoropropyl and cyanopropyl radicals. Particularly preferred radicals R7 are the methyl, vinyl and phenyl radicals.
Examples of the radicals R8 containing epoxy groups are the epoxyethyl, 2,3-epoxypropyl, 3,4-epoxybutyl, 5,6-epoxyhexyl, 9, 10-epoxydecyl, glycidyloxy, 3-glycidyloxypropyl, glycidyloxyisobutyl, 2-methylglycidyloxypropyl, 3-phenylglycidyloxypropyl, glycidyloxyphenylnonyl, glycidyloxybenzylethyl, 3,4-epoxycyclohexyl, 2-(3,4-epoxycyclohexyl)ethyl, 3-(3,4-epoxycyclohexyl)propyl, 1,4-epoxycyclohexyl and 2-(1,4-epoxycyclohexyl)ethyl radicals. Preferred radicals R8 are the 3,4-epoxycyclohexyl, 3-(3,4-epoxycyclohexyl)propyl and glycidyloxypropyl radicals. Radical R8 preferably has 2 to 10 carbon atoms. A particularly preferred radical R8 is the glycidyloxypropyl radical.
Examples of the monovalent hydrocarbon radicals substituted by an acryloyloxy or methacryloyloxy group and having 2 to 20 carbon atoms are mentioned above for R7. Hydrocarbon radicals which have no heteroatoms, in particular having 2 to 10 carbon atoms, such as ethyl, propyl or butyl radicals, are preferred.
Examples of the radicals R9 are
a) alkoxy, enoxy or aryloxy groups of the general formula xe2x80x94OR10, such as the methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, 2-ethylbutoxy, 2-ethylhexyloxy, vinyloxy, allyloxy, isopropenyloxy, cyclobutenyloxy, cyclohexenyloxy, 1,3-butadienyloxy, propargyloxy, phenoxy, benzyloxy, and m- or p-vinylbenzyloxy radicals;
b) acyloxy groups of the general formula xe2x80x94OCOR10, such as the formyloxy, acetoxy, 2-ethylhexanoyloxy, acryloyloxy, methacryloyloxy, benzoyloxy and norbornylacetoxy radicals;
c) amino groups of the general formula xe2x80x94NH2, xe2x80x94NHR10 or xe2x80x94NR102, such as the dimethylamino, diisopropylamino, allylamino, n-butylamino, sec-butylamino and cyclohexylamino radicals;
d) oxime groups of the general formula xe2x80x94ONxe2x95x90CH2, xe2x80x94ONxe2x95x90CHR10 or xe2x80x94ONxe2x95x90CR102, such as the methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl n-amyl ketoxime, and dimethyl ketoxime radicals;
e) amido groups of the general formula xe2x80x94NHxe2x80x94C(xe2x95x90O)xe2x80x94R10 or xe2x80x94NR10xe2x80x94C(xe2x95x90O)xe2x80x94R10, such as the N-methylbenzamido or N-methylacetamido radicals;
f) aminoxy groups of the general formula xe2x80x94ONH2, xe2x80x94ONHR10 or xe2x80x94ONR102, such as the hydroxylamino radical; or
g) those derivatives of the abovementioned radicals which are halogen-substituted and/or contain heteroatoms or have a more complex composition, such as the p-aminophenoxy, 2-methoxyethoxy, 1-methoxy-2-propoxy, 1-methoxyisopropenyloxy, methoxyethoxyethoxy, 1-methoxy-2-methylpropenyloxy, acryloyloxymethoxy, meth-acryloyloxy-(polyethyleneoxy), furyloxy or N-vinylformamido radical and xe2x80x94O-Ph-C(xe2x95x90O)-Ph, xe2x80x94Oxe2x80x94C(CF3)xe2x95x90CHxe2x80x94Cxe2x95x90O)xe2x80x94CF3, xe2x80x94Oxe2x80x94C(CH3xe2x95x90CHxe2x80x94C(xe2x95x90O)xe2x80x94CH3, xe2x80x94Oxe2x80x94C(CH3)2xe2x80x94CHxe2x95x90CH2, xe2x80x94NHxe2x80x94C(xe2x95x90O)xe2x80x94CH3, xe2x80x94Oxe2x80x94C(xe2x95x90O)xe2x80x94CH2Br, xe2x80x94Oxe2x80x94C(xe2x95x90O)xe2x80x94CF3, xe2x80x94Oxe2x80x94C(xe2x95x90O)xe2x80x94Cxe2x89xa1CH or xe2x80x94Oxe2x80x94CH2xe2x80x94C(xe2x95x90O)xe2x80x94Oxe2x80x94Si(CH3)3,
where the radicals R10 represent monovalent aliphatic or aromatic, saturated or unsaturated, optionally halogen-substituted hydrocarbon radicals having 1 to 10 carbon atoms. Preferred radicals R9 are the alkoxy radicals such as the methoxy, ethoxy, propoxy and butoxy radicals. The particularly preferred radical R9 is the methoxy radical.
Preferred as organosilicon compound (D), are organofunctional silanes, glycidyloxypropyltrimethoxysilane (Glymo), vinyltrimethoxysilane, vinyltriethoxysilane and methacryloyloxypropyltrimethoxysilane being particularly preferred.
The radicals R1 to R10 in all above formulae may be identical or different. Preferred heteroatoms are N, O and S. Preferred halogen substituents are F, Cl and Br.
Hydrosilylation catalyst (E) serves as a catalyst for the addition reaction, termed a hydrosilylation, between the aliphatically unsaturated hydrocarbon radicals R2 of the diorganopolysiloxanes (A) and the silicon-bonded hydrogen atoms of the organohydrogenpolysiloxanes (C). Numerous suitable hydrosilylation catalysts are described in the literature. In principle, all hydrosilylation catalysts corresponding to the prior art and used in addition-crosslinking silicone rubber materials can be used.
For example, metals and their compounds such as platinum, rhodium, palladium, ruthenium and iridium, preferably platinum, can be used as hydrosilylation catalysts (E). The metals can optionally be fixed on finely divided support materials, such as active carbon, metal oxides such as alumina, or silica.
Platinum and platinum compounds are preferably used. Particularly preferred platinum compounds are those which are soluble in polyorganosiloxanes and are inert at a storage temperature up to 40xc2x0 C. but catalyze the hydrosilylation sufficiently rapidly on heating.
Preferred platinum catalysts (E) include those selected from compounds of the general formulae xe2x80x83Hxe2x80x94Cxe2x89xa1Cxe2x80x94(R14)fxe2x80x94Cxe2x89xa1Cxe2x80x94[xe2x80x94Pt(R11)xe2x80x94Cxe2x89xa1Cxe2x80x94(R14)fxe2x80x94Cxe2x89xa1Cxe2x80x94]exe2x80x94Hxe2x80x83xe2x80x83(8),
in which
R11 denotes an optionally substituted diene which is bonded to platinum by at least one xcfx80-bond and represents a straight or a branched chain having 4 to 12 carbon atoms or a cyclic ring having 6 to 18 carbon atoms,
R12 may be identical or different and denotes a hydrogen atom, trialkylsilyl radical, halogen atom or monovalent hydrocarbon radical optionally substituted by halogen atoms or cyano radicals and having 1 to 24 carbon atoms,
R13 denotes identical or different divalent, optionally substituted hydrocarbon radicals having 1 to 24 carbon atoms,
R14 may be identical or different and denotes divalent, optionally substituted hydrocarbon radicals having 1 to 12 carbon atoms, silane radicals or siloxane radicals,
R15 may be identical or different and denotes a hydrogen atom or a monovalent hydrocarbon radical having 1 to 20 carbon atoms,
e denotes an integer greater than or equal to 1 and
f is 0 or 1.
If R11 is a substituted diene or the radicals R13 and R14 are substituted hydrocarbon radicals, preferred substituents are halogen atoms, such as F, Cl, Br and I, cyano radicals, xe2x80x94NR152 and groups xe2x80x94OR15, R15 having the above-mentioned meaning.
Cyclooctadiene complexes of platinum having acetylide ligands, as described in EP-A-994 159, are particularly preferred, especially bis(alkynyl)(1,5-cyclooctadienyl)platinum, bis(alkynyl)(1,5-dimethyl-1,5-cyclooctadienyl)platinum and bis(alkynyl)(1,6-dimethyl-1,5-cyclooctadienyl)platinum complexes.
With the use of the platinum catalyst of the general formulae 5 to 8, the crosslinkable silicone compositions are marketable as a 1-component formulation and have a long shelf-life, in particular of at least 3 months at 25xc2x0 C. and ambient pressure, and crosslink rapidly only at a high temperature. In the preparation of the crosslinkable silicone compositions, it is especially advantageous that the platinum catalyst (E) of the general formulae 5 to 8 can readily be incorporated, that the hydrosilylation reaction does not slow down in the course of the reaction, and that no platinum colloids are formed and no discolorations result through their use.
Peroxide crosslinking agents (E) which may be used are inorganic and organic peroxides, in particular organic peroxides. Examples of such organic peroxides are peroxyketals, e.g. 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and 2,2-bis(tert-butylperoxy)butane; acyl peroxides such as acetyl peroxide, isobutyl peroxide, benzoyl peroxide, di(4-methylbenzoyl) peroxide and bis(2,4-dichlorobenzoyl) peroxide; dialkyl peroxides such as di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; and peresters such as tert-butyl peroxyisopropylcarbonate.
The self-adhesive crosslinkable 1-component silicone compositions preferably contain 10 to 90% by weight, more preferably 25 to 60% by weight, of diorganopolysiloxane (A); 10 to 80% by weight, more preferably 20 to 60% by weight, of filler (B); 0.1 to 20% by weight, more preferably 0.5 to 5% by weight, of organohydrogenpolysiloxane (C), and 0.1 to 10% by weight, more preferably 0.2 to 2% by weight, of organosilicon compound (D).
The amount of the hydrosilylation catalyst (E) used depends on the desired crosslinking rate and economic points of view. Usually, 1xc3x9710xe2x88x925 to 5xc3x9710xe2x88x922% by weight, in particular 5xc3x9710xe2x88x924 to 5xc3x9710xe2x88x923% by weight of platinum catalysts, calculated as platinum metal and based on the weight of the silicone compositions, are used.
The amount of the peroxide crosslinking agent (E) used is preferably 0.1 to 5% by weight, more preferably 0.2 to 3% by weight, based on the weight of the silicone compositions.
The self-adhesive crosslinkable 1-component silicone compositions can optionally contain further constituents (F), such as nonreinforcing fillers, inhibitors, stabilizers, pigments and catalysts. All components (A) to (F) may contain a single compound or a mixture of different compounds.
The self-adhesive crosslinkable 1-component silicone compositions preferably have a Mooney viscosity, determined at 25xc2x0 C. according to DIN 53523 Par t 3, of 15 to 150, more preferably 23 to 95.
The compounding of the self-adhesive crosslinkable 1-component silicone compositions is effected by mixing the abovementioned components in any desired sequence. The thermal crosslinking of the silicone compositions is effected by heating, preferably at 40 to 250xc2x0 C., more preferably at least 50xc2x0 C., most preferably at least 100xc2x0 C., preferably at not more than 200xc2x0 C., and most preferably at not more than 180xc2x0 C.
The invention also relates to the silicone elastomers obtainable by crosslinking the self-adhesive crosslinkable 1-component silicone compositions. The self-adhesive crosslinkable 1-component silicone compositions can be bonded to a substrate by applying the silicone compositions to the substrate followed by crosslinking, preferably by heating to 30 to 250xc2x0 C., to give a composite material, and can advantageously be used, in particular, wherever good adhesive strength between the silicone elastomer and a substrate, preferably a substrate of organic plastics, metals or glasses, is desired. The substrate may be present as a molding, film or coating.
The silicone compositions are suitable for the production of composite materials by coating, adhesive bonding, or casting, and for the production of shaped articles. The silicone compositions are particularly suitable for encapsulating and for adhesively bonding electrical and electronic components and for the production of composite moldings such as composite insulators for medium and high voltage applications. Composite moldings are understood as meaning a shaped article comprising a composite material which is composed of a silicone elastomer part produced from the silicone compositions and at least one substrate, so that there is a strong, permanent bond between the two parts. Such a composite molding is preferably produced by processing a metal or oxidic base element or organic plastic to give a shaped article and then bringing the silicone compositions into contact with this molding and crosslinking them, which can be effected, for example, by injection molding, by means of extrusion, and in a so-called press-molding method. These processes are exemplary and not limiting. Composite insulators are produced, for example, by sheathing rods or tubes of glass fiber-reinforced plastics. Composite materials and in particular composite moldings can be used in a very wide range of applications, for example, in the electronics, household appliances, consumables, construction and automotive industry, in medical technology, in the production of sport and leisure articles, etc.
In the following examples, unless stated otherwise in each case, all pressures are 0.10 MPa (abs.); all temperatures are 20xc2x0 C.; and all viscosities are measured at a temperature of 25xc2x0 C. | {
"pile_set_name": "USPTO Backgrounds"
} |
In certain networks, specific fields within message headers are used as binary keys to search data structures for specific details regarding actions necessary for appropriate processing of those messages. The length of a binary key is dependent on the size of the field(s) used to create the key. A few example key lengths may include 32 bits for an IP address, 48 bits for an Ethernet MAC address, or 104 bits for a TCP/IP 5-tuple. It is impractical to use these keys in their full form to directly address corresponding entries due to the length of the keys. This can theoretically be done in content addressable memory (CAM), but typically creates practical disadvantages because of the cost of a CAM of such size. Hence, a common approach is to hash the value of the binary key and use a pre-selected first portion of the hashed value to address a specific entry in a hash table. Hashing can be accomplished by creating a new value of the binary key having the same number of bits, which are unique to any given binary key, and then using only a portion of the bits, e.g. the first N bits to select the corresponding hash table entry. This value is then used to address a specific entry in a hash table, sometimes referred to as a direct table DT. Either the entire hashed value or the remaining portion of the hashed value is stored in a data structure, together with the corresponding function-specific data denoted by the binary key. Whenever a binary key is extracted from received messages, its value is hashed and the first portion of the hash value is used to access an entry in the hash table. If a valid hash table entry is found, that location in the hash table points to a data structure containing a complementary portion of a reference hash value that is compared with the equivalent complementary portion of the hash value generated from the message key to confirm the validity of the key and declare the associated action if the key is, in fact, valid. This works well for some numbers; however, in some cases, the first portion of the hashed value of one binary reference key is the same as the first portion of the hashed value of another binary reference key. This occurs because only a portion of the newly created value of the binary key is used to select an entry in the hash table and, hence, this portion of the new value of one binary key may be the same as that of another binary key. This is often referred to as a “collision”. In the past, this has been dealt with by the use of patricia tree structures or the like. But this is cumbersome and relatively slow. Hence, a faster relatively inexpensive technique is needed. | {
"pile_set_name": "USPTO Backgrounds"
} |
Contact lenses are commonly worn by users to correct vision, or for cosmetic or therapeutic reasons. Usually, melanin is dispersed in the contact lens to protect eyes from harmful radiation. However, melanin may be easily diluted by tears when in use. | {
"pile_set_name": "USPTO Backgrounds"
} |
The present invention generally relates to a process for diffusing titanium and nitride into a material. More specifically, a process is provided for diffusing titanium and nitride into a material having a coating thereon.
The present invention relates to a low temperature process for diffusing titanium and nitride into a base material having a coating thereon in the presence of electrolyzed titanium. A low temperature process is preferred in that it prevents or lessens warping and twisting of the material. Titanium is considered a generally inert, light-weight material which has very high tensile strength (or toughness) and excellent corrosion resistance. Accordingly, because of their inert nature, increased hardness, increased tensile strength and increased resistance to wear, products containing titanium may be used in various applications including industrial, biomedical, aerospace, automotive, defense, jewelry, tools, tool-making, gun-making applications and other such applications.
U.S. Pat. No. 6,645,566, which is incorporated by reference herein and made a part hereof, describes a process for diffusing titanium and nitride into a variety of base materials including steel and steel alloys, aluminum and aluminum alloys, titanium and titanium alloys. Nevertheless, U.S. Pat. No. 6,645,566 does not describe a method for diffusing titanium and nitride into a material having a coating thereon.
Various materials (e.g., carbide, metal and metal alloys) are used in applications which require hardness, tensile strength and/or resistance to wear. Although these materials may inherently include these attributes, it is desirable to further enhance such. Accordingly, various surface treatment and coating processes have been applied to these materials. Conventional surface treatment and coating processes may include, but are not limited to, heat treatment, nanocoating, ceramic coating, Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), Ion Assisted Coating (IAC), and other suitable surface treatments or coating. These conventional processes are typically preferred because they extend the life of the material at a lower cost than replacement of such.
Nevertheless, a coating is only as good as the strength of the bond between the coating and the substrate material. Good adhesion is an important prerequisite in engineering a commercially useful coating process. For this reason, a number of coating processes have been developed, each attempting to improve the interfacial strength between the coating and the base material.
In one example, conventional surface treatments and coating processes have been typically applied to steel and steel alloys. Steel and steel alloys are generally known to contain a high content of iron. Some conventional surface treatment processes, such as in some Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD) and Ion Assisted Coating (IAC) processes, involve nitriding, wherein nitrogen is introduced such that it reacts to iron in the steel or steel alloy to form a hardened ferrous nitride layer. This reaction causes the formation of a hardened ferrous nitride layer, which serves as a suitable coating on the base material.
These nitriding processes, however, are generally deficient when treating materials which contain a relatively low content of iron (e.g., carbide). As such, when applying these processes to such materials, there is generally not enough iron for nitrogen to react with. Accordingly, conventional nitriding surface treatments cannot generally form a hardened ferrous nitride layer on the base material due to its low iron content. Instead, a coating is formed which has a weak adhesion with the base material surface, thereby causing it to be susceptible to chipping.
It is therefore an object of the present invention to diffuse titanium and nitride into a material having a coating thereon, in order to enhance the coating in and of itself. It is also an object of the invention to provide a process which allows for the implementation of the enhanced properties of titanium in both the coating and the base material. | {
"pile_set_name": "USPTO Backgrounds"
} |
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