A non-volatile memory device includes a memory cell array and a voltage control unit. The memory cell array includes a plurality of memory blocks each including a plurality of cell strings. Each of the cell strings includes a first selection transistor, a second selection transistor, and at least one memory cell transistor serially connected between the first selection transistor and the second selection transistor. The voltage control unit provides first selection line voltages and word line voltages to first selection lines connected to the first selection transistors and word lines connected to the memory cell transistors, respectively, in response to a plurality of block selection signals corresponding to the plurality of memory blocks, and provides a second selection line voltage directly to second selection lines connected to the second selection transistors independently of the block selection signals

1. Field of the Invention
The present invention relates to a non-volatile memory device, and more particularly, to a non-volatile memory device and programming, reading, and erasing methods thereof.
A claim of priority is made to Korean Patent Application No. 10-2006-0106716, filed Oct. 31, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
2. Description of the Related Art
F-N tunneling is utilized to program and erase cell transistors contained in non-volatile memory devices, such as NAND type flash memory devices.
For example, F-N tunneling is induced in an erase operation by applying a low voltage (e.g., 0V or ground) to a control gate of a cell transistor, and by applying a high voltage (e.g., 20V) which exceeds a supply voltage to a semiconductor substrate (or bulk) containing the cell transistor. The resultant large voltage differential causes a strong electric field to be formed between the floating gate and the bulk, and F-N tunneling occurs in which electrons are discharged from the floating gate to the bulk. This causes the threshold voltage (Vth) of the erased cell transistor to shift in a negative direction (e.g., Vth≦−3V). In conventional terms, the erased state is designated as data "1", and a cell transistor in this state is referred to as an "ON" cell.
In a program operation, for example, a high voltage (e.g., 18V) which exceeds a supply voltage is applied to the control gate of the cell transistor, and a low voltage (e.g., 0V or ground) is applied to the drain of the cell transistor and to the semiconductor bulk. When the cell transistor is biased in this manner, F-N tunneling results and electrons are injected to a floating gate of the cell transistor. This causes the threshold voltage (Vth) of the programmed cell transistor to shift in a positive direction (e.g., Vth≧+1V). The programmed state is conventionally designated as data "0", and the cell transistor is referred to as an "OFF" cell.
FIG. 1 is a block diagram of a conventional NAND type flash memory device 100. The NAND type flash memory device 100 includes a memory cell array 110, a row selecting circuit 130, a row decoder circuit (not shown), a page buffer circuit 150 (or a data sensing and latching circuit), and a column decoder circuit 170.
The memory cell array 110 includes a plurality of memory blocks BLK0 through BLKn each having a plurality of cell strings (n is a positive integer). As illustrated in FIG. 1, each of the cell strings includes of a string selection transistor SST connected to a corresponding bit line, e.g., a bit line BL0, a ground selection transistor GST connected to a common source line CSL, and memory cell transistors MC15 through MC0 connected between the string selection transistor SST and the ground selection transistor GST. Each of the memory cell transistors MC15 through MC0 forms a memory cell. FIG. 1 illustrates the example of 16 memory cells per cell string, but the number of memory cells contained in each string may vary among different NAND flash memory devices.
As shown in FIG. 1, the string selection transistor SST, the memory cells MC15 through MC0, and the ground selection transistor GST are respectively gated to a string selection line SSL, word lines WL15 through WL0, and a ground selection line GSL. Further, as shown, block selection transistors BS17 through BS0 are respectively connected between the lines SSL, WL15 through WL0, and GSL, and lines SS, Si15 through Si0, and GS. The block selection transistors BS17 through BS0 are commonly controlled by a block selection signal BS.
The row selecting circuit 130 is responsive to the row decoder (not shown) to select a word line (or a page) from among the word lines WL0 through WL15 via block selection transistors BS0 through BS17. In a programming mode, the page buffer circuit 150 temporarily stores data to be stored in memory cells of the selected word line (or page). In a read mode, the page buffer circuit 150 senses data stored in the memory cells of the selected word line (or page). The page buffer circuit 150 includes a plurality of page buffers (or data sensing and latching blocks) which respectively correspond to rows (bit lines) related to the selected page. Data bits that are sensed (read) from the memory cells of the selected page are output via the column decoder circuit 170 in predetermined units, e.g., in units of bytes X8.
FIG. 2 is a circuit diagram of another flash memory device 200. This device is at least partially characterized in that wirings for providing voltages to the string selection lines SSL are metal-strapped to one another, as are the wirings for providing voltages to the ground selection lines GSL.
In a standby state prior to the read operation, both the string selection lines SSL and the ground selection lines GSL are discharged to ground voltage. When the read operation is performed, a supply voltage (e.g., VPP) is applied as a block selection signal to the selection transistors of a selected block, while a ground voltage (e.g., 0V) is applied as a block selection signal to the selection transistors of a non-selected block
During the read operation, the voltages of the string selection line SSL and the ground selection line GSL of the selected block are increased from the ground voltage (0 V) to a read voltage VREAD. Further, a ground voltage (0V) is applied to a selected word line WLm of the selected block, and the read voltage is VREAD is applied to the unselected word lines WL0˜WLm−1 and WLm+1˜WLn. In this state, data is read out from the cell transistor(s) of a selected bit line(s).

Non-volatile memory device and programming, reading and erasing methods thereof


A cutting device with an auto-retractable blade, having a housing containing an active blade extendable from a front aperture thereof and a spare blade box therein. An actuator is provided being fixed to an actuator seat contained in and slidable with respect to the housing. The actuator seat has a side protrusion having a front dent defined therein. A blade seat is slidably contained in the housing. The blade seat has an upper fulcrum, a side protrusion, a side blocker, a blade installation plate, a lower fulcrum, and a blade seat return spring. The side protrusion has a front slope and a back tip which is receivable in the front dent of the actuator seat.

1. Field of the Invention
The invention relates to a cutting device, and more particularly, to a cutting device having both an auto-retractable blade and a spare blade box contained in a housing thereof.
2. Description of the Prior Art
Cutting device is a commonly used hand tool for cutting, e.g., wood, paper, leather, plastic panel, cord, and cardboard. It often has a housing made up of two covers detachably coupling together. The housing acts as both a handle and a container for a blade slidably received therein. An actuator is provided in an aperture defined in the handle for moving the blade.
In order to avoid hurting persons after cutting, some utility knives having auto retractable blade are provided. A blade of the cutting device is able to retract back into the housing when a user releases the actuator after cutting. However, dangers still exist when a user, who is abstracted or not agile enough to release the actuator, waves the cutting device to himself or other with his finger pressing on, the actuator and the blade extending after leaves a workpiece.
Cutting devices with a retractable blade in which the blade automatically retracts into the handle before a clumsy user can bring it toward himself or toward anyone else after a cutting edge of the blade leaves a workpiece are disclosed in U.S. Pat. No. 7,765,701 and U.S. Patent Application Publication No. 2009/0277016. Both cutting devices have a blade seat having a long tail extending backward and a hook formed on an also backward extending pole driven by a thumb actuator. In work, a user is able to move the actuator forward, and the hook will drive the long tail, thus the blade seat, forward, too. When the blade cuts the workpiece, the blade seat rotates and the long tail leaves the hook. As the blade leaves the workpiece, the blade seat is driven back by a spring. When the user releases the actuator, the pole is driven back by another spring and engages with the long tail again for next time use.
It is a trend for current utility knives that they all need to have an integral spare blade box defined in the housing thereof. A cutting device lack of integral spare blade box brings much inconvenience. However, all prior automatically retractable utility knives do not have such a spare blade box. The long tail and the backward extending pole occupy much of a rear portion of the housing, which usually belongs to, the spare blade box. Since the rotation of the blade in cutting is a very tiny one, a journey of travel of the backward extending pole to disengage with the long tail of the blade seat in cutting must be enlarged by a leverage mechanism. In another words, if there were not the long tail and the backward extending pole, a distance between the actuator and the blade seat before and after the cutting is too small for the actuator to credibly engage with the blade seat.


A communication channel is established between a master station and one of plural remote stations in a multi-channel access (MCA) cordless telephone system. Access data is transmitted from the master station to all of the remote stations, at the same time, to designate a selected remote station as a representative station. The access data also includes calling data which seeks a response from that representative station. In the absence of a response to the calling data from the previously designated representative station, the station identifying data is changed to designate a new remote station as the representative station. The foregoing process is repeated until a representative station responds to the calling data, whereupon the remote stations are polled, in sequence; and a communication channel is established between the master station and the particular polled station which replies to the polling operation.

1. Field of the Invention
This invention relates to multi-channel access (MCA) cordless telephones of the type generally described in copending application Ser. No. 403,477, filed Sept. 6, 1989 and assigned to the same assignee as the present invention; and, more particularly, to an MCA-type cordless telephone system in which several remote stations, such as handset units, may be queried simultaneously for the purpose of establishing a communication channel with one of them, within a brief period of time.
2. Description of the Prior Art
Cordless telephone systems of the multi-channel access type which rely upon relatively low electrical power requirements have been proposed heretofore. In one such proposal, eighty-seven separate communication channels and two separate control channels are provided, each channel being a "cordless" communication path having a particular carrier frequency onto which information and data are modulated. To expand the functions of an MCA cordless telephone system, a so-called "multi-cordless" arrangement has been introduced in which a master station is comprised of plural base units, each including a set of transmitting and receiving circuits adapted to communicate with one of several remote stations, such as handset units.
An example of the aforementioned multi-cordless telephone arrangement is illustrated in FIG. 1 in which one master station, such as base unit 2, is adapted to communicate with plural remote stations, such as the eight handset units 1A, 1B, . . . 1H that are illustrated. Base unit 2 is connected to a conventional telephone line 3 and is adapted to communicate with the handset units by way of radio transmission between the antenna provided at the base unit and each of the antennas provided at the handset units.
In the arrangement shown in FIG. 1, when an incoming telephone call is received from telephone line 3 to base unit 2, the base unit signals all of handset units 1A-1H at the same time, whereupon one of the handset units responds and, thus, answers the incoming telephone call. Typically, the following techniques are used to signal the handsets and complete a telephone call:
In one technique, base unit 2 signals each of handsets 1A-1H individually and in sequence. At the completion of the entire sequential signalling operation, that is, after the last handset has been signalled, the base unit awaits the response from a handset which wishes to answer the telephone call.
Another technique relies upon simultaneous signalling of all of the handsets, with the expectation that only one handset, that is, the desired handset unit, will respond.
As yet another technique, all of handset units lA-1H are signalled at the same time, but the signalling identifies a particular handset unit as a "representative handset unit" which is the only unit enabled to respond. Thus, although other "non-representative" units receive the signal from base unit 2, they are inhibited from responding thereto and, thus, are not able to answer the incoming telephone call.
All of the aforementioned techniques suffer from various disadvantages and drawbacks. The first technique, which signals individual handset units in sequence, requires an unusually long period of time to complete the sequential signalling and to answer the incoming telephone call. This is because the handset units are not maintained in a steady receive-enable mode of operation so as to detect base unit signalling. Rather, in an effort to minimize the power requirements of the handset units (due to the fact that these units typically are energized by a battery), a handset unit typically is disposed in a quiescent or "sleep" mode from which it is "awakened" to its receive mode only periodically. For example, and as shown in FIG. 2A, in a 2-second period, the handset unit may be disposed in its receive mode for only 0.2 seconds, while remaining in its quiescent, power-down mode for the remaining 1.8 seconds. Thus, a handset unit is enabled only briefly to receive the signalling transmitted from base unit 2. Furthermore, the periodicity illustrated in FIG. 2A, which illustrates the changeover between the quiescent and receive modes of a handset unit, is not synchronized in all of handset units 1A-1H. Although the repetition rates of these changeover operations may be about the same, the instantaneous times at which the handset units are changed over from their quiescent mode to their receive mode are random.
Accordingly, to ensure that a signal from base unit 2 will be detected by each of handset units 1A-1H, the base unit transmits this signal periodically over a predetermined interval to handset unit 1A, then to handset unit 1B, and so on. As illustrated in FIGS. 2A and 2B, the signal transmitted from the base unit may exhibit a duration of only 120 milliseconds, but this signal is repealed continuously for a period of approximately 2.5 seconds to make certain that the signal is present when handset unit 1A is disposed briefly in its receive mode. It is expected that the handset unit receives the signal from base unit 2 at a time t2, whereafter this handset unit does not return to its quiescent mode but, rather, remains in its receive mode, as represented by the broken line shown in FIG. 2A. Following the end of the 2.5 second signalling interval, which occurs at time t3, the signalled handset unit responds at, for example, time t4, as illustrated in FIG. 2C. This "answer back" signal is delayed by an amount & following the end of the signalling interval. The "answer back" signal is detected at base unit 2 to establish a communication channel between the base unit and the responding handset unit (assumed herein to be handset unit 1A).
In a typical MCA cordless telephone system, the signalling from base unit 2 to a handset unit and the "answer back" from that handset unit are carried out over a control channel which, typically, is separate and distinct from the communication channel. Since the use of the control channel for other purposes generally is not permitted, a handset unit is inhibited from responding to the signalling from the base unit until all of the handset units have been signalled. Once this signalling is completed, the base unit awaits the receipt of an "answer back" from one of the handset units, whereafter a call indicator at that handset unit, such as a ringing device, is energized. It is appreciated that if 2.5 seconds are needed to signal one handset unit successfully, twenty seconds (2.5 seconds .times.8 handset units) are needed to call all of the handset units. This unusual time delay is unacceptable, especially since an incoming telephone caller may discontinue his telephone call long before it is completed on the assumption that the called party (i.e. base unit 2 in combination with handset units 1A-1H) is not available to "answer".
In the second signalling technique mentioned above, wherein all of the handset units are signalled simultaneously, the time needed to establish a communication channel between the base unit and one handset unit is substantially reduced from that just described. However, it is not unusual for two or more handset units to transmit "answer back" signals to the base unit at time t4. As a result, radio interference between these simultaneously transmitted "answer back" signals prevents the base unit from determining which handset unit wishes to establish the communication channel. Hence, communication is prevented.
In the third of the aforementioned techniques for establishing communication between the base unit and a handset unit, wherein only the representative handset unit is permitted to response to the signalling, the drawbacks generally attending the other two techniques are avoided. However, if the representative handset unit is unable to receive the signal transmitted from base unit 2, or if the representative handset unit is unable to communicate with the base unit, for example, if its battery power is low, if it has malfunctioned or if another cordless telephone in close proximity therewith monopolizes the control channel, or if it is located beyond the effective communication range with the base unit, the signalling process is stopped. That is, base unit 2 is unable to establish communication with the representative handset unit or with any other handset unit. Consequently, an incoming telephone call cannot be "answered" if there is no reply from the representative handset unit, regardless of the reason for that lack of reply.

Multi-channel access cordless telephone system


Previous research demonstrated that aflatoxin contamination in corn is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillus flavus strain NRRL 30797. We evaluated the reliability and efficiency of replacing wheat grains with the novel bioplastic formulation Mater-Bi® to serve as a carrier matrix to formulate strain NRRL 30797. Mater-Bi® granules were inoculated with a conidial suspension of NRRL 30797 to achieve a final cell density of ˜log 7 conidia/granule. Incubation of 20-g soil samples receiving a single Mater-Bi® granule for 60-days resulted in log 4.2 to 5.3 propagules of A. flavus/g soil for microbiologically active and sterilized soil, respectively. The bioplastic formulation was highly stable; Mater-Bi® is a suitable substitute for biocontrol applications of A. flavus NRRL 30797.

1. Field of the Invention
This invention relates to a novel biocontrol formulation for the prevention of contamination of plants by toxins produced by fungi, i.e., toxigenic Aspergillus spp. and the control of seedling and root diseases. The novel biocontrol formulation comprises biocontrol agents and bioplastic carrier granules, Mater-Bi® granules. The biocontrol agents of the formulation can comprise non-toxigenic strains of Aspergillus spp. which are capable of inhibiting growth of fungi that produce aflatoxin and further capable of suppressing production of aflatoxin by the toxigenic fungi or the biocontrol agents can comprise Trichoderma virens strains capable of inhibiting damping off in horticultural plants. The present invention relates to a biocontrol strategy whereby the biocontrol formulation comprising a non-toxigenic A. flavus strain and Mater-Bi® is applied to crops as a method for reducing aflatoxin contamination in corn and other crop plants.
2. Description of the Relevant Art
Augmentative biological control is generally perceived as a pest management tactic that utilizes the deliberate introduction of living natural enemies to lower the population level of invasive pests (DeBach and Rosen. 1991. In: Biological Control by Natural Enemies, Cambridge University Press, Cambridge). Biological control has been utilized for more than 100 years in efforts to control a wide number of agricultural pests including fungi, insects, and weeds (Siddiqui and Mahmood. 1996. Biores. Technol. 58: 229-239; Stiling and Cornelissen. 2005. Biol. Control 34: 236-246). Biocontrol strategies have been implemented to control aflatoxin contamination in several important agricultural crops, such as peanut, cotton, and corn (Abbas et al. 2006. Biocontrol Sci. Technol. 16: 437-449; Cotty, P. J. 1994. Phytopathology 84: 1270-1277; Dorner et al. 1992. J. Food Protect. 55: 888-892). Aflatoxins are highly carcinogenic secondary metabolites produced by several species of Aspergillus section flavi, including A. flavus Link, A. parasiticus Speare, and A. nominus Kutzman, Horn and Hesseltime. Of these, A. flavus is the most abundant aflatoxin-producing species associated with corn (Abbas et al. 2004a. Can. J. Bot. 82: 1768-1775; Abbas et al. 2004b. Can. J. Microbiol. 50: 193-199; Abbas et al. 2008. J. Agric. Food Chem. 56: 7578-7585; Wicklow et al. 1998. Mycol. Res. 102: 263-268). A. flavus is readily isolated from diverse environmental samples; however, soil and crop residues are considered the natural habitat of this fungus (Abbas et al. 2008, supra). In addition, soil serves as a reservoir of conidia (spores) which can infect susceptible crops (Scheidegger and Payne. 2003. Toxin Rev. 22:423-459).
Management of aflatoxin-producing fungi in corn is a difficult task, requiring an integrated approach including optimization of agronomical practices (i.e. irrigation, fertilization, etc.). These practices promote the general health of corn and can reduce, but not eliminate aflatoxin contamination (Cleveland et al. 2003. Pest Manag. Sci. 59: 629-642). Consequently, there is a need for additional, practical and cost-effective strategies to limit aflatoxin contamination of corn (Cleveland et al., supra). One attractive option to supplement, but not supplant these agronomical practices is biological control. Aflatoxin biological control programs can truly be defined as bio-competition since they do not utilize parasites or diseases of the pest, but instead use atoxigenic Aspergillus spp. to competitively exclude toxigenic fungi. Further, other fungal biocontrol agents such as Trichoderma have the potential to inhibit and displace damping-off fungi and other soil born diseases on a wide range of horticultural crops (Paulitz and Belanger. 2001. Ann. Rev. Phytopathology 39:103-133; Elliott et al. 2009. Biocontrol Sci. Tech. 10:1007-1021).
Surveys conducted in multiple geographical regions have found that not all strains of A. flavus produce aflatoxins (Abbas et al. 2004a, supra; Cotty and Bhatnagar. 1994. Appl. Environ. Microbiol. 60: 2248-2251). Current biocontrol strategies rely upon the ability of non-aflatoxigenic strains to competitively exclude indigenous aflatoxin-producing Aspergilli (Cleveland et al., supra). Successful reduction of aflatoxin contamination through the introduction of competitive non-aflatoxin producing strains of A. flavus has been demonstrated in a number of crops, including corn (Dorner et al. 1992, supra; Dorner, J. W. 2005. In: Aflatoxin and Food Safety, Abbas, H. K., Ed., CRC Press, Taylor & Francis Group, Boca Raton, pp. 333-352). Biocontrol fungi are typically applied to soil as alginate pellets, pregelatinized starch-flour granules, or colonized grains (Dorner, J. W. 2008. Food Addit. Contam. 25: 203-208; Honeycutt and Benson. 2001. Plant Dis. 85: 1241-1248; Lewis et al. 1998. Plant Dis. 82: 501-506). Among some of the successful formulations, a pasta-like product (Pesta) and a coated hulled-barley formulation (Afla-Guard®) have proven to be effective for delivering non-aflatoxigenic strains of A. flavus, as well as other biocontrol fungi (Connick et al. 1998. Biol. Control 13: 79-84; Singh et al. 2007. Biores. Technol. 98: 470-473; Dorner, supra). Application of these protocols has also been shown to be highly effective in recent studies conducted by the USDA-ARS at the Stoneville, Miss. research station. In these efforts, Abbas et al. (2006, supra) demonstrated that aflatoxin contamination in corn is dramatically reduced by field application of non-aflatoxin producing A. flavus strain NRRL 30797 (K49). In Abbas et al. (2006, supra) conidia of the competitive non-aflatoxigenic strain were applied to soil as inoculated wheat grains.
Various biocontrol methods and formulations for effective control of toxigenic fungi in cotton, peanuts, and corn are known in the art, as discussed above. However, there still remains a need for formulations of biocontrol agents which are effective for ensuring the integrity and effectiveness of the biocontrol agent after long term storage, for facilitating handling, and for field application of the biocontrol agent. Novel granular bioplastic biocontrol compositions comprising non-aflatoxigenic and non-toxigenic A. flavus strains and methods of using a novel granular bioplastic biocontrol composition to effectively reduce aflatoxin contamination in corn and other crop plants are provided. The need for suitable formulation systems to deliver other fungi used in biological control of plant diseases is also evident. Thus, an example of the use of bioplastic material to deliver Trichoderma virens to control damping-off disease caused by Rhizoctonia solani is also disclosed.

Granular bioplastic biocontrol composition

The United States of America, as represented by The Secretary of Agriculture


The present invention relates to a method of detecting and localizing gamma radiation from a target source in the possible presence of background gamma radiation, said method comprising the steps of:                a) detecting the directional intensity distribution of gamma rays with respect to a preferred direction,        b) analysing the direction dependence, correcting for efficiency and solid angle of the detection means,        c) determining the amount and spatial distribution of background radiation,        d) determining the background contribution of the intensity measured in the preferred direction from the amount and spatial distribution of background radiation,        e) determining the strength of gamma radiation in a preferred direction by subtracting from the intensity measured in the preferred direction any background contribution from non preferred directions.

The labelling of tissue with radioactive substances is a well established method in medical diagnosis and surgery. Employing radiation detecting devices the specific uptake of radioactivity, e.g. in malignant tissue, is detected and localized. Various types of gamma cameras provide scintigraphic images of the radiation distribution within a patient for diagnostic purposes. However, they are too bulky and too slow for radio guided surgery. Hand-held gamma probes with a head consisting of a radiation detector, shielding and a collimator are widely used for that purpose (e.g. WO 02/44755 A2). Such a probe is moved by the surgeon across a suspected region of the patient to locate e.g. cancerous tissue manifested by excess radiation as compared to the surrounding.
The activity injected into a patient should be kept as low as possible for the sake of the patient and the medical staff. This requires the detection efficiency of the gamma probe to be as large as possible. Assuming a point-like gamma source, the detection efficiency is predominantly determined by the solid angle covered by the gamma detector and by the detection efficiency. Large volume detectors cannot be used since the probe head needs to be light-weight and compact to allow for accurate manoeuvring and precise pointing at tumour manifestations. Therefore dense scintillators or solid state diodes composed of heavy elements are mandatory. More important, the distance of the detector to the target needs to be minimized. Assuming a typical distance of malignant tissue to the body surface of 10 mm, the detection efficiency of a probe placed directly at the body surface is four times respectively nine times larger than the efficiency achievable at 10 mm and 20 mm apart from the surface. Collimation of the field of view as discussed below often requires retracted position of the detector. These conditions lead to a generally accepted minimal efficiency corresponding to a sensitivity of about 5 cps/kBq and thus to a minimal required activity of a few kBq for a target to be detectable.
Unfortunately, gamma rays from the labelled site tend to scatter off the surrounding tissue and organs, thereby contributing to a diffuse radiation background rendering the localization of the original source difficult. In addition commonly employed radio pharmaceuticals enrich non-selectively in organs like liver or brain and are present throughout the whole body to some extent. Therefore intense background radioactivity is prevalent near tumour sites. One possibility to distinguish a scattered gamma ray from a direct gamma ray emitted by a source is by its energy. Only gamma rays coming in direct line from the source into the detector possess their full energy, whereas in any scattering process some energy is lost. Employing an energy sensitive detector and selecting events with the full gamma ray energy therefore allows to suppress background of scattered gamma rays. This method is only applicable with radio isotopes which emit gamma rays of one energy like 99mTc, while isotopes with several gamma transitions (e.g. 111In: 171 keV, 245 keV) are excluded. Moreover, not all gamma rays are fully absorbed in the detector. Depending on the type and size of scintillator or solid state diode used as detector, and on the energy of the gamma ray, the majority of gamma rays may deposit only part of their energy and will thus be assigned to background. Consequently the remaining rate of accepted direct gamma rays from a source may be severely lowered, reducing the sensitivity to detect and locate malignant tissue unless the statistical accuracy is re-established by an increased activity applied to the patient.
Another approach to suppress not only the background of scattered gamma rays but also the background radiation from other sources nearby the suspected tumour site is to utilize shielding and collimating material with the detector. Shield and collimator are made from dense, heavy metals like lead or tungsten alloys, yielding highest gamma ray absorption. The collimator is meant to define the field of view of the detector. For proper location particularly of small tumours high spatial selectivity is demanded, which requires a narrow opening cone of the collimator (compare H. Wengenmair et al.; Der Nuklearmediziner Nr. 4, 22 (1999) 271). The narrower the cone the smaller is the body volume contributing to the background signal, while the target signal from a tumour stays constant. At a distance of 30 cm (far field) the full width at half maximum (FWHM) of the radial signal rate distribution, determined by the cone and detector geometry, should be ≦40° for universal gamma probes. For cases with close-by background sources or unfavourable target to background ratio a narrower distribution is preferable. In typical applications the distance of the radiation sensitive part of the probe to the tissue to be inspected is about 10 mm. To distinguish close lying point-like sources, e.g. neighbouring lymph nodes, the spatial resolution of the probe at close distance (near field) to the target needs at least to be <25 mm. For the localization of very small lymph nodes for example prevalent in head and neck regions a near field precision of <15 mm FWHM is necessary. On the other hand a too narrow collimation is counter productive if large body regions need to be scanned during surgery. In that case a wider cone is preferable to shorten the screening time. Exchangeable and adjustable collimators (see e.g. U.S. Pat. No. 5,036,201, U.S. Pat. No. 4,959,547) are used with available gamma probes to adopt the cone characteristics to the application.
Background radiation may hit the probe from almost any direction. Therefore collimation and shielding needs to protect the detector from all sides but the opening cone. It was even suggested to use large shields external to the gamma probe (U.S. Pat. No. 5,148,040). In the worst case the injection depot of a radio pharmaceutical may be located in the vicinity of the probe with an activity 1000 times above the activity of cancerous tissue. Shield thickness of <4 mm is sufficient to provide an optimal absorption factor of >103 for background radiation of 140 keV energy emitted by 99mTc. Already for 364 keV gamma rays of the radio isotope 131I the attenuation of strongest absorbers, like tungsten, is no longer sufficient to reach this background suppression factor. To keep the weight of the probe well below 1 kg and the head diameter below 25 mm a maximal shield thickness of 9 mm is applicable, yielding a suppression factor of about 20. Increasing the shield thickness to 18 mm tungsten or 25 mm lead would reestablish the wanted background reduction. However, in that case the probe head would become too heavy and too bulky to be suitable.
For many medical applications PET radio pharmaceuticals like 18F-FDG turn out to be superior over conventional low energy tracers because of much higher specific concentration in malignant tissue, potentially leading to higher sensitivity and selectivity. However, for the 511 keV gamma rays of 18F-FDG the suppression factor of 9 mm thick tungsten is only 10 which severely limits the use of state-of-the-art probes for many applications.
As such, there is a need for a gamma probe, which may be employed in detecting and localizing gamma rays of 511 keV and even higher energies, which avoids the above mentioned restriction of contemporary art probes.

High energy gamma probe with position sensing capability

GFE Gesselschaft fur Forschungsund Entwicklungsservice mbH


An engine assembly includes an engine block defining a first cylinder bore, a second cylinder bore directly adjacent to the first cylinder bore and a third cylinder bore directly adjacent to the second cylinder bore. The engine block defines a first distance from a diametrical center of the first cylinder bore to a diametrical center of the second cylinder bore and defines a second distance from the diametrical center of the second cylinder bore to a diametrical center of the third cylinder bore. The first distance is different than the second distance.

This section provides background information related to the present disclosure which is not necessarily prior art.
Internal combustion engines may combust a mixture of air and fuel in cylinders and thereby produce drive torque. Combustion of the air-fuel mixture produces exhaust gases. Engines may include intake ports to direct air flow to the combustion chambers. Typically, the cylinders have a common spacing along the engine block based on the size of the largest cylinder bore even in arrangements including varying cylinder bore sizes along the length of the engine block.

Engine assembly including multiple bore center pitch dimensions


The instant invention is related to a method for replicating an object. The method includes providing an object comprising an outer surface and a channel; applying dry tannin powder to the outer surface of the object wherein at least a portion of the dry tannin powder adheres to the outer surface as imaging tannin; and placing an aqueous solution of an iron salt in the channel wherein the iron salt diffuses through the object to convert said imaging tannin into a replica of the object.

The present invention is related to methods for forming reproductions which mimic legacy stock images, or multidimensional objects, using modern printing techniques and inks. More specifically, the present invention provides a method for forming a reproduction utilizing iron gall ink printing methods coupled with ink jet image or diffusion production methods. More specifically, the present invention is related to reproduction techniques wherein a, preferably legacy, stock image or multidimensional object is reproduced to provide a reproduction which mimics the stock image or multidimensional image yet the image has an iron gall ink appearance suggestive of an original image or object.
Many legacy images or objects are electronically available to the public as stock items. These images can be downloaded and printed using modern printing techniques, such as by an ink jet printer, or mimicked by 3-dimensional printing or forming techniques to be enjoyed by a new generation. Alternatively, it may be desirable to form a new image or object having an appearance associated with ancient printing techniques, such as iron gall printing, thereby providing an image or item appearing to be quite old. Iron gall printing provides a hue and depth which is unique yet the cost of reproduction using iron gall printing is not financially feasible and the image durability is not suitable.
It has long been the desire of art enthusiast to recapture legacy images or objects in some form which is representative of iron gall printing without the effort and cost associated with actually printing a true iron gall image. It has long been the desire of art enthusiast to replicate stock images, particularly legacy images and objects, cheaply using modern printer techniques while achieving the visual effect associated with iron gall images.
The present invention provides a reproduction technique suitable for use with two-dimensional and three-dimensional elements wherein the image is transformed to one having a visual effect similar to an original iron gall image.

Multidimensional image reproduction technique


Apparatus and method for training a football player the proper technique of catching the football comprises a football tethered with an elastic cord which is releasably attached to a stationary object at its opposite end. A second person grasps the football and stands a distance from the stationary object such that the elastic cord is pulled taut and stretched beyond its normal, relaxed length. The training player stands between the second person and the stationary object adjacent the cord and assumes a position ready to receive a pass. The second person simply releases the football which then travels to the training person along the path of the cord who attempts to catch the ball.

This invention relates to sports training aids and, more particularly, to a football training aid and method designed to train a player to receive a pass.
In the game of football, it is very important that players learn proper techniques of catching the ball, as in a forward or lateral pass, or a snap from center. Various training devices have been developed to train football players in an attempt to increase their skills at passing, kicking and receiving a football. Quick repetitions of the proper body movements required to successfully pass, kick or receive the football have proven an effective training method. Training aids developed heretofore have thus typically taken the form of a tethered ball which returns in the proximity of the player following execution of the practice pass or kick such that prolonged retrieval of the ball is avoided and repetitions of shorter intervals may be made.
For example, U.S. Pat. No. 4,350,338 issued to Randall May on Sept. 21, 1982 discloses a tethered football having a harness arrangement for placement along the seams of the football which is used to return a passed or punted football. Similarly, U.S. Pat. No. 1,655,599 issued to Dolan, Jr. on June 21, 1923 discloses a tethered football having wing flaps used for practice kicking. It is obvious that a specially designed football is required to practice the Dolan patent and that the harness arrangement of May is prone to slippage and breakage. More importantly however, neither the May nor Dolan patents disclose or suggest the use of a tethered football for practice pass receiving, or otherwise aid in sharpening a player's skills in catching the ball.
It is therefore a main object of the present invention to provide a football training aid and method which is designed to effectively train a player to catch a moving ball.
It is a further object to provide a football training aid and method which permit quick repetitions of receiving the same practice football by a player.
It is another object to provide a football training aid and method which require no passing ability on the part of the player who delivers the practice football to the receiving player.
It is still another object to provide a football training aid which is simple in design and use, yet fully effective at training a football player to receive a pass in a variety of positions encountered under actual game conditions.
Other objects will in part be obvious and in part appear hereinafter.

Method and apparatus for ball catch training


Precision measuring machine (10) has a bed (12) with a tailstock (14) and headstock (16) mounted thereon. Anvils (36, 42) are respectively mounted on the tailstock and headstock. Duct walls enclose the lower portion of the bed so that fan (62) can move air therepast. Cap shrouds (72, 82) receive air from fan shrouds (68, 84) to flood air over the tailstock and headstock. Anvil shrouds (76, 90) respectively cover anvils (36, 42) and receive air through tubes (80, 92) to also flood the anvils with air. In this way, the precision measuring machine is bathed in ambient air to reduce dimensional changes due to temperature changes.

Because of the thermal coefficient of expansion of the parts of a measuring machine, stable temperatures are required for accurate measurement. Precision measuring machines have heavy beds, heavy measuring stocks and heavy tailstocks. An anvil is fixed on the tailstock, and a movable anvil is fixed on the headstock. The movable anvil has a precision readout gage thereon. The anvils are placed at a known distance from each other by movement of the headstock and/or tailstock by use of a reference or standard gage block therebetween. The reference block is removed and a part to be measured is placed therein. The readout indicates the difference in dimension between the standard block and the part now between the anvils. The moving anvil and its readout have a very small movement so that movement of the stock on the bed and recalibration are often required. The physical handling of the stocks and even the radiation from the hands when positioning parts to be measured put heat into the measuring machine. The increase in temperature causes dimensional changes in the machine to reduce the measuring accuracy thereof. It is necessary to wait until the temperature is again stabilized before measuring can proceed. Thus, there is need for a way to decrease the amount of heat entering the precision measuring machine and to quickly remove heat added thereto.

Air-cooling system for precision measuring machines


An apparatus for handling tubular goods which includes an elongate body having a coupling end adapted for mating engagement with a tubular good. The coupling end includes a structural member, a flexible cylindrical cage and a pressure member. Longitudinal strips joined at their opposed ends form the cage coaxial with and connected to the structural member of the body. The coaxial pressure member is disposed in an annulus between the structural member and the cage. The pressure member is adapted to cause radial displacement of the cage, thereby exerting a gripping force to maintain the mating engagement between the tubular good and the coupling end enabling a transfer of force between the body and the tubular good.

The manufacture, assembly and use of tubular systems in drilling and constructing wells, frequently involves operations where the tubular work piece must be gripped and handled to enable the application of axial and torsional loads. Devices employing jaws, such as elevators, tongs or pipe wrenches are commonly used to engage the pipe body directly, with the risk of damage by distortion of the pipe or marking by the jaw faces. Where the tubular ends are threaded, adapters may be used to temporarily engage the threads and transfer load running the risk of damaging the threads. The present invention provides a means to internally friction grip a tubular work piece with an expandable cage, and apply assembly, handling and drilling loads through an attachment.
Historically, petroleum drilling rigs have used an architecture where drilling torque is applied through a rotary table placed in the derrick floor. The rig mast is used to support the block and tackle equipment for hoisting tubular strings comprised of individual joints of pipe connected by threaded connections, in and out of the drilled hole or well. With this architecture, it is inconvenient to use the rotary table to apply torque to make up or break out the connections. Tongs are therefore typically used to apply and react make up or break out torque, by externally gripping the pipe ends to be connected directly above and below the threaded connection. This well known procedure is used to make up and break out drill pipe, casing and tubing to trip tubular strings in or out of the well. In the case of casing and tubing, the method is typically incorporated into devices, referred to as power tongs, which provide a means to apply continuous rotation and torque through a motor and gear box assembly. However these devices still require external grips, typically using some form of jaws as described, for example, in U.S. Pat. No. 5,172,613. Whether powered or not, this method requires that one tong grip the upper end of the pipe joint suspended from the rotary table in the derrick floor, to provide a reaction for the torque applied through a second tong which is used to grip and rotate the pipe joint being made up or broken out. The upper end of the pipe joint being rotated is supported by an elevator, hanging from the travelling blocks, thus allowing rotation and providing limited freedom to translate laterally.
However recent advances in drilling rig technology have resulted in increased use of rigs having a new architecture, and known in the industry as top drive rigs. As the name suggests, these rigs are equipped with a hydraulic or electric drive head unit that moves up and down the rig mast constrained by a track, thus enabling the application of rotational force from any position. These rigs employ a drive head capable of applying torque and axial load to the top of the pipe through an output shaft known as a xe2x80x9cquill,xe2x80x9d and typically employ more automated and powered pipe-handling equipment than conventional rigs. This configuration allows the tubulars to be made up and broken out using the top drive to rotate and apply torque to the top joint, but necessitates a method of coupling the quill to the tubular capable of transmitting full make up or break out torque and at least some axial load.
For tubing and casing, this is typically accomplished using a threaded make up adapter, commonly referred to as a xe2x80x9cnubbinxe2x80x9d, threaded on the lower end to match the tubing or casing thread and on the upper end to match the thread on the quill. A device capable of stroking up and down and transmitting torque, commonly referred to as a floating cushion sub, is also often placed between the quill and the nubbin to accommodate thread make up and break out length change without top drive movement. This laterally rigid and flexurally stiff device effectively forms an extension of the quill.
Unlike the conventional make up and break out method using tongs, this method of top drive make up requires extra steps to handle, install and remove the nubbin, increasing the time and consequently, the cost of running tubulars. In addition, the risk of thread damage is increased by the extra make up and break out to the nubbin required for each joint run in or out of the well.
This method of top drive make up further exacerbates the potential for connection thread damage because the rigid lateral positioning of the top drive at the top end of the joint, where it is supported during rotation. This prevents the tendency of the thread axis to xe2x80x9cself alignxe2x80x9d as otherwise occurs when the top of the joint is suspended from the cable-supported travelling block on conventional rigs, allowing relatively free lateral movement. Although the axes of the pin and box threads are generally parallel when the connection is stabbed, tolerances for rig mast position with respect to the hole axis, pipe straightness and threading can all conspire to allow significant misalignment. Under these conditions, the potential for connection damage is aggravated by alignment constraints as imposed by relatively rigid support at the upper end of joints. Contrast this with the greater freedom of motion allowed on conventional rigs when the travelling block supports the upper end of the pipe. During rotation of the connection at the lower end, this alignment constraint tends to prevent the pin and box thread axes from self aligning which results in a tendency toward xe2x80x98cross threadingxe2x80x99 of the connection when significant tolerancing errors exist, with consequent high internal contact stress and galling susceptibility. In many instances known to the inventors, this misalignment has resulted in connection damage and improperly made-up connections.
It is therefore desirable to have a method for gripping the pipe without contacting the threads and that allows the top end of the pipe to displace laterally with relative freedom.
Methods using jaws on the exterior of the pipe to apply torque without contacting the threads are numerous. As mentioned above, jaws are typically employed with power tongs. Torque activated jaws such as described in U.S. Pat. No. 5,172,613, are the most typical architecture but the tendency of this method to mark and damage the pipe has led to more controlled active gripping systems such as described in U.S. Pat. No. 5,172,613. To further avoid xe2x80x9ccausing surface damage or structural deformationxe2x80x9d, more nearly uniformly radial loading, friction grips, such as described in U.S. Pat. No. 4,989,909 are known as a means to grip the exterior of tubulars where tolerance to damage is low. While these methods provide a generally satisfactory means for gripping the exterior of pipe, they are not amenable to use in conjunction with a top drive. Gripping the interior of the pipe avoids the need to apply torque through the coupling, or to invoke more complex means to bypass the connection, while all the time avoiding interference with other pipe handling equipment, such as elevators. Neither do these methods address intolerance to connection thread misalignment, which is peculiar to the top drive make up and break out method.
The device/method of the present invention was therefore conceived specifically as a means to friction grip the inside of the tubular and thus provide the capacity to transfer torque and carry most of the axial handling loads presently provided by nubbins. It will also shorten the handling time requirements, eliminate nubbin contact with the threads, and provide increased lateral compliance to accommodate the tendency for top end of the pipe to move off axis during make up.
To meet these objectives, the method of the present invention makes use of a device having an upper end provided with a crossover sub to attach to the quill and having a lower coupling end provided with a grip assembly, which may be inserted into the top end of a tubular work piece to be handled, and expanded to engage or grip the inside surface of the tubular joint. The grip method and contacting element preferably frictionally engage the inside wall of the tubular with a uniform distribution of radial loading virtually eliminating the risk of marking or distorting the pipe or connection. It will be understood that such attachment to the top drive quill may be direct or indirect to other intermediate components of the drill string such as a xe2x80x98thread saver subxe2x80x99 essentially forming an extension of the quill.
The upper adapter is coupled to the grip assembly by means of a tube having upper and lower universal joints which enable lateral movement during transmission of torque, as is commonly employed in applications where torque is transmitted over some length, such as in automobile drive shafts flexibly coupled through universal joints. The grip assembly is further arranged to permit the grip to be activated, or set, by application of right hand torque and deactivated or released by application of left hand torque when a first operating mode is engaged. In a second operating mode, either left or right hand torque is transferred directly through the grip without changing the grip force. The first or setting mode is engaged by application of slight axial compressive load, or by setting the quill down. The second or direct torque mode is engaged by application of slight tension or by lifting the quill up once the grip is set. These simple, fast and direct means of gripping and releasing provide substantial operational improvements over the existing methods.
The primary purpose of the present invention is to provide a method employing an internal gripping device for handling tubular work pieces in general and particularly suited to perform make up and break out of pipe joints being run in or out of a well with a top drive drilling rig, having as its gripping mechanism a sub-assembly comprised of:
1. a generally cylindrical expandable cage with upper and lower ends,
2. a structural member is provided in the form of a mandrel. Mandrel has upper and lower ends placed coaxially inside the cage where the lower ends of the mandrel and cage are attached, and where the external diameter of the cage is somewhat less than the internal diameter of the tubular work piece to be gripped, allowing the cage to be positioned within the tubular work piece,
3. a significant annular space between the inside surface of the cage and the outside surface of the mandrel,
4. a pressure member disposed in the lower interval of the annular space between the mandrel and cage as an expansion element and
5. means to activate the expansion element to cause the cage to expand and frictionally engage the inside surface of the tubular work piece with sufficient radial force to enable the mobilization of friction to transfer significant torque and axial load from the upper end of the mandrel through the cage to the tubular.
Said expandable cage of the gripping mechanism having a lower and upper end:
is preferably comprised of a plurality of flexible strips aligned largely axially along the body of the cage and attached to cylindrical sleeves at each end of the cage,
where the edges of adjacent strips are preferably profiled to provide interleaving tabs or fingers,
which fingers permit cage expansion or radial displacement of the strips but tend to prevent cage twist or shear displacement between strips under torsion loading.
Said means to provide cage expansion is preferably provided by:
a largely incompressible elastomeric material disposed in the lower interval of the annular space between the mandrel and cage,
means to confine the ends of the elastomeric material and if necessary further means to confine the outer sides of the elastomeric material across gaps that may exist between adjacent edges of the cage strips to prevent excess extrusion of the elastomeric material when compressed, and
means to axially compress the annular elastomeric material with sufficient force to cause the cage to expand and frictionally engage the inner surface of the tubular enabling transfer of torque and axial load from the upper end of the mandrel through the cage to the tubular.
An additional purpose of the present invention is to provide a tubular gripping and handling device having said gripping sub-assembly joined to an external load and torque application device, such as the quill of a top drive rig, through a load transfer member or drive shaft, flexibly coupled at each end where such flexible couplers function as universal joints enabling transfer of torque with little or no moment or lateral resistance.
This purpose is preferably realized by:
providing a crossover sub configured to thread to the quill on its upper end and connect to a tubular or hollow drive shaft at its lower end,
by means of pins engaging slots in the upper end of the drive shaft thus providing the function of a universal joint, where
a similar slotted and pinned connection is provided to join the lower end of the drive shaft to the upper end of the gripping mechanism sub-assembly.
A further purpose of the present invention is to provide a means to flow fluid and apply pressure through the top drive adapter and into the tubular work piece being gripped. This purpose is realized by providing a flow path through the crossover sub, drive shaft and tool mandrel and is preferably augmented by provision of an internal cup seal, such as a packer or swab cup, attached to the lower end of the mandrel to prevent leakage into the annular space between the mandrel and inside surface of the tubular work piece.
In applications, where the lifting capacity of the frictional grip is insufficient to reliably support the hoisting loads required to run assembled tubular strings into or out of a well, the make up and break out functions provided by the tubular handling and gripping assembly, must be supplemented by the addition of hoisting equipment. In a manner well known to the industry, such hoisting equipment may be provided as elevators. However, to support applications where suitable elevators may not be available or convenient to use, it is a further purpose of the present invention to provide additional means to support hoisting loads, integral with the frictional grip device.
This purpose is realized by providing an external hoisting sub-assembly, which sub-assembly is comprised of:
a largely cylindrical hoisting sleeve coaxially placed outside the internal gripping subassembly having an upper end attached to the upper end of the internal gripping subassembly, a lower end extending downward to overlap an interval of the tubular work piece, typically to the lower end of the collar typically attached to the upper end of casing or tubing joints, and lower end configured with internal grooves,
a plurality of jaw segments, preferably provided as a collet where the upper end of the collet fingers are attached, and the lower end of the collet fingers carry the jaw segments configured to mate on their interior with the outside surface of the tubular work piece and on their exterior with ribs engaging the internal grooves of the hoisting sleeve where the spring action of the collet is preferably arranged so the jaws tends to contact the work piece,
where the mating ribs and grooves of the jaw and hoisting sleeve surfaces respectively tend to force the jaws inward under application of hoisting load, in the manner of slips, well known to the industry as a method of providing load transfer between hoisting equipment and tubular goods, and
means to retract the jaws to facilitate disengaging from the tubular work piece, which means is preferably linked to the operation of the internal friction grip so that the jaws may only be retracted when the tool is not set or activated.

Method and apparatus for handling tubular goods


A piezoelectric ceramic that includes barium titanate and 0.04 mass % or more and 0.20 mass % or less manganese relative to barium titanate. The piezoelectric ceramic is composed of crystal grains. The crystal grains include crystal grains A having an equivalent circular diameter of 30 μm or more and 300 μm or less and crystal grains B having an equivalent circular diameter of 0.5 μm or more and 3 μm or less. The crystal grains A and the crystal grains B individually form aggregates and the aggregates of the crystal grains A and the aggregates of the crystal grains B form a sea-island structure.

1. Field of the Invention
The present invention relates generally to piezoelectric ceramics, methods for making the piezoelectric ceramics, piezoelectric elements, liquid discharge heads, and ultrasonic motors. In particular it relates to a barium titanate piezoelectric ceramic that has controlled crystal grain size and thereby exhibits good piezoelectric performance and mechanical strength, a method for making the piezoelectric ceramic, a piezoelectric element that uses the piezoelectric ceramic, and a liquid discharge head and an ultrasonic motor that use the liquid discharge element.
2. Description of the Related Art
ABO3 perovskite oxides such as lead zirconate titanate (hereinafter referred to as "PZT") are generally used as piezoelectric ceramics.
However, since PZT contains lead as the A-site element, PZT may have an adverse effect on the surrounding environment. Accordingly, piezoelectric ceramics that use lead-free perovskite oxides are sought after.
Barium titanate is known as a lead-free perovskite piezoelectric ceramic material. Japanese Patent Laid-Open No. 2008-150247 discloses barium titanate prepared by a resistance heating/two-step sintering technique. The '247 also discloses that when nano-sized barium titanate powder is sintered by the two-step technique, a ceramic that has a maximum grain diameter of 5 μm or less and good piezoelectric characteristics is obtained.
However, according to the two-step sintering technique, the retention time of the first sintering temperature needs to be short. As a result, the temperature of the ceramic to be sintered becomes inhomogeneous and the piezoelectric characteristics are not always satisfactorily reproduced. For example, the temperature of a barium titanate ceramic piece of a practical size does not become homogeneous if the retention time is about 1 minute. In other words, an ideal nanostructure is not realized in all parts of the sintered ceramics. Thus, there have been no barium titanate ceramics that achieve piezoelectric characteristics sufficient to replace PZT.
The piezoelectric performance of barium titanate may be improved by increasing the crystal grain diameter. Japanese Patent No. 4039029 discloses the relationship between the average grain diameter of a calcium-doped barium titanate ceramics and the piezoelectric constant. The piezoelectric constant (d31) is increased when the average grain diameter of the piezoelectric ceramic is increased from 1.3 μm to 60.9 μm.
In Japanese Patent No. 4039029, the average grain diameter of the ceramic is controlled by adjusting the time of wet-mixing of calcined powders. In addition, the average grain diameter of the ceramic is increased by increasing the primary firing temperature.
However, when the average grain diameter of the barium titanate ceramic is increased by the aforementioned techniques, the contact area between the crystal grains is decreased. Thus, the mechanical strength of the ceramic drops and ceramic parts become fragile during processing and driving of the piezoelectric element. In sum, it is desirable that barium titanate piezoelectric ceramics achieve both good piezoelectric characteristics and high mechanical strength.

Piezoelectric ceramic, method for making the same, piezoelectric element, liquid discharge head, and ultrasonic motor


A resistive memory device and a method for manufacturing the same are disclosed. The resistive memory device includes a lower electrode formed over a substrate, a resistive layer disposed over the lower electrode, an upper electrode formed over the resistive layer, and an oxygen-diffusion barrier pattern provided in an interface between the resistive layer and the upper electrode. The above-described resistive memory device and a method for manufacturing the same may prevent the out diffusion of oxygen in the interface of the upper electrode to avoid set-stuck phenomenon occurring upon the operation of the resistive memory device, thereby improving the endurance of the resistive memory device.

The present invention relates to a technology of manufacturing a semiconductor device, and more particularly, to a resistive memory device which utilizes a change in resistance, such as in nonvolatile Resistive Random Access Memory (ReRAM) devices, and a method for manufacturing the same.
Recently, researchers are actively studying next-generation semiconductor memory devices which can replace Dynamic Random Access Memory (DRAM) and flash memory.
One of such next-generation semiconductor memory devices is a resistive memory device utilizing a material whose resistance changes rapidly according to an applied bias to switch between at least two different resistance states, that is, a resistive layer. As a resistive layer having such characteristics, binary oxide including transition metal oxide or perovskite-based material has been used.
The structure of the resistive memory device and its switching mechanism are briefly described hereinafter.
Generally, a resistive memory device has a structure including upper and lower electrodes and a resistive layer located between the upper and lower electrodes. When a predetermined bias is applied to the upper and lower electrodes, a filamentary current path may be generated due to oxygen vacancies in the resistive layer, or the generated filamentary current path may disappear following the elimination of the generated oxygen vacancies. The resistive layer represents two resistive states which are distinguished from each other due to the generation or elimination of the filamentary current path. That is, when the filamentary current path is generated, a state where resistance is low, that is, a set state, is formed, and when the filamentary current path is eliminated, a state where resistance is high, that is, a reset state, is formed.
However, repeated write/erase operations of the resistive memory device may cause a set-stuck phenomenon, in which it is impossible to return from a set state to a reset state. In order to return from the set state to the reset state, it is required to fill oxygen vacancies with oxygen of an upper electrode interface to eliminate the filamentary current path. However, since the oxygen of the upper electrode interface is diffused out as time passes, the oxygen around the upper electrode interface becomes insufficient.
As a result, the resistive memory device is weak with respect to an endurance of framework, and this property makes it difficult to substantially utilize the resistive memory device as a memory device.

Resistive memory device and method for manufacturing the same


In one embodiment, a method includes receiving a stored copy request indicating data and including a request identifier, scheduling publication of the data to an object store, and sending a subscription request indicating the data and the request identifier to the object store. In another embodiment, a method includes receiving a publication request indicating data to be copied, wherein the publication request is a recording request indicating a channel and a timespan, receiving one or more subscription requests for the data, receiving the data, and generating a copy of the data for each subscription request.

The ongoing development, maintenance and expansion of storage systems often involves providing storage of data for multiple users. As the number of users increases, the amount of signaling, bandwidth used, and metadata stored increases, degrading the efficiency of the storage system.
In accordance with common practice various features shown in the drawings may not be drawn to scale, as the dimensions of various features may be arbitrarily expanded or reduced for clarity. Moreover, the drawings may not depict all of the aspects and/or variants of a given system, method or apparatus admitted by the specification. Finally, like reference numerals are used to denote like features throughout the figures.


A medical retrieval device includes a basket formed of two or more legs. The basket may be used to retrieve material (e.g., a urinary stone) from a body. The basket opens and closes for encapsulation of a stone. A captured stone may be released from the basket with the basket still in the body by opening the legs. The baskets exhibit shapes and configurations designed to optimize the characteristics of flexibility, ease of material capture, and ease of material release.

Medical retrieval devices may include devices for removing organic material (e.g., blood clots, tissue, and biological concretions such as urinary, biliary, and pancreatic stones) and inorganic material (e.g., components of a medical device or other foreign matter), which may obstruct or otherwise be present within a body's anatomical lumens. For example, concretions can develop in certain parts of the body, such as in the kidneys, pancreas, and gallbladder. Minimally invasive medical procedures generally involve causing limited trauma to the tissues of a patient, and can be used to dispose of problematic concretions. Lithotripsy and ureteroscopy, for example, are used to treat urinary calculi (e.g., kidney stones) in the ureter of a patient.
Lithotripsy is a medical procedure that uses energy in various forms such as acoustic shock waves, pneumatic pulsation, electrical hydraulic shock waves, or laser beams to break up biological concretions such as urinary calculi (e.g., kidney stones). The force of the energy, when applied either extracorporeally or intracorporeally, usually in focused and continuous or successive bursts, divides a kidney stone into smaller fragments that may be extracted from the body or allowed to pass through urination.
When stones are fragmented within a body tract by a lithotripter, the stone must first be stabilized. Typically, a medical retrieval device, such as a surgical grasper or a metal wire basket, is used to capture a stone in the retrieval assembly. With the stone held in position within the retrieval assembly, a lithotripter, such as a laser lithotriptor, comes into proximity with the stone and the stone is fragmented by the lithotriptor. After the stone is fragmented, the stone fragments can be removed by the same or a different medical retrieval device, or the fragments can be left in the body to be eliminated naturally. With the help of imaging tools such as transureteroscopic video technology and fluoroscopic imaging, the operator of the lithotriptor device can monitor the progress of the medical procedure and terminate treatment when residual fragments are small enough to be voided or removed with minimal trauma.
Retrieval of intracorporeal fragments of urinary calculi can be problematic in that stones and/or stone fragments in the ureter often migrate within the body before, during, and after a lithotripsy procedure. Therefore, a need exists in the art for a retrieval device that facilitates the initial capture of material as well as maintaining capture of material during further positioning and removal of the captured material and retrieval device. In addition, there also exists a need in the art for a retrieval device that facilitates the controlled release of a stone or fragment during a surgical procedure. For example, controlled release of material is often required to reposition a target stone relative to a lithotriptor or release a captured stone of a size too large for removal without fragmentation.
Thus, it is desirable to have configurations for medical retrieval devices that exhibit improved capabilities for sustained capture, controlled release, and limited patient tissue trauma.


Provided is a fusion protein comprising IL-2 protein and CD80 protein. A fusion protein comprising CD80 fragment, immunoglobulin Fe, and an IL-2 variant can activate immune cells, such as natural killer cells, and at the same time, can control immune cell regulatory activity of regulatory T cells. Therefore, a pharmaceutical composition comprising the fusion protein as an active ingredient is very industrially useful in that such pharmaceutical composition can increase immune activity in the body, and thus can be effectively used against infectious diseases as well as cancer.

Interleukin 2 (IL-2), also called T-cell growth factor (TCGF), is a globular glycoprotein that plays a central role in lymphocyte production, survival, and homeostasis. IL-2 has a protein size of 15.5 kDa to 16 kDa and consists of 133 amino acids. IL-2 mediates various immune actions by binding to an IL-2 receptor composed of three distinct subunits.
In addition, IL-2 is synthesized mainly by activated T cells, in particular by CD4+ helper T cells. IL-2 stimulates proliferation and differentiation of T cells, and induces production of cytotoxic T lymphocytes (CTLs) and differentiation of peripheral blood lymphocytes into cytotoxic cells and lymphokine-activated killer cells (LAK cells).
Furthermore, IL-2 is involved in proliferation and differentiation of B cells, promotes immunoglobulin synthesis by B cells, and stimulates production, proliferation, and activation of natural killer cells (NK cells). Therefore, IL-2 is used as an anticancer agent, because it can increase lymphocyte populations and increase the function of the immune cells in the living body. Currently, therapy with IL-2 has been approved and used for patients with metastatic renal cell carcinoma and malignant melanoma.
However, IL-2 has a dual function in immune responses in that it is important not only for mediating an increase in number of immune cells and activity thereof, but also for maintaining immune tolerance. In addition, it has been reported that IL-2 may not be optimal for inhibiting tumor growth. The reason is that in the presence of IL-2, activation-induced cell death (AICD) may occur in the resulting cytotoxic T lymphocytes and immune responses may be inhibited by IL-2-dependent regulatory T cells (Treg cells) (Imai et al., Cancer Sci 98, 416-423, 2007).
In addition, severe cardiovascular, pulmonary, renal, hepatic, gastrointestinal, neuronal, cutaneous, hematological, and systemic side effects occur in patients who have received immunotherapy with IL-2. Therefore, various IL-2 mutations have been studied to improve therapeutic efficacy of IL-2 and minimize side effects thereof (U.S. Pat. No. 5,229,109 B). However, there are still many problems to be solved in order to utilize IL-2 for pharmacological purposes.
Meanwhile, CD80, also known as B7-1, is a member of the B7 family of membrane-bound proteins that are involved in immune regulation by binding to its ligand by way of delivering costimulatory responses and coinhibitory responses. CD80 is a transmembrane protein expressed on the surface of T cells, B cells, dendritic cells, and monocytes. CD80 is known to bind CD28, CTLA4 (CD152), and PD-L1. CD80, CD86, CTLA4, and CD28 are involved in a costimulatory-coinhibitory system. For example, they regulate activity of T cells and are involved in proliferation, differentiation, and survival thereof.
For example, when CD80 and CD86 interact with CD28, costimulatory signals are generated to activate T cells. Eventually, CD80 binds to CTLA4 and stimulates CTLA4 to be upregulated. As a result, CD80 inhibits T cell responses prior to immune response activation caused by CD80/CD28 interaction. This feedback loop allows for fine regulation of immune responses.
In addition, CD80 is known to bind PD-L1, another B7 family member, with affinity similar to that with which CD28 binds PD-L1. PD-L1 is known as one of two ligands for programmed death-1 (PD-1) protein, and PD-L1 is known to be involved in T cell regulation. Binding of CD80 to PD-L1 is another mechanism that can block PD-1/PD-L1 interaction, which may prevent inhibition of T cell responses in tumors. At the same time, however, an increase in CD80 levels causes CD80 to bind to CD28 so that CTLA4 is induced, thereby inducing or inhibiting T cell responses.

Fusion protein comprising IL-2 protein and CD80 protein, and use thereof


A composition of matter comprising an acrylamido-acyl or methacrylamido-acyl oligomer derived from at least one nucleophilic oligomer having at least one amino-, hydroxyl-, or thiol-substituted polyoxyalkylene, polyalkyleneimine, polyester, polyolefin, polyacrylate, or polysiloxane oligomer, said nucleophilic oliogmer having a molecular weight in the range of 200 to 20,000 is disclosed. Also disclosed are free radially polymerizable monomer-containing compositions containing said oligomers as well as acrylamido- and methacrylamido-acylated polymers which are the thermal or photocured products of said oligomers. In addition, a process is disclosed for providing said acrylamido- and methacrylamido-acylated oligomers which are useful, for example, in coatings, films, printing inks, adhesives, and saturants.

It is known in the art to prepare acrylic-functional resin compositions by direct esterification of alcohols or polyols with (meth)acrylic acid or its derivatives, as disclosed in U.S. Pat. No(s). 3,010,925 and 4,101,477. Inherent difficulties in such processes include the need for solvents and for relatively high reaction temperatures, the latter requiring that suitable precautions be taken to prevent premature polymerization. In order to overcome these and other difficulties, U.S. Pat. No(s). 3,297,745, 3,700,643, 4,131,602, and others have taught that 100% solids, copolymerizable polyacrylic urethane monomers and resins can be prepared from hydroxyalkyl acrylates, polyisocyanates, and polyols. Copolymerizable monoacrylic-urethane monomers of this type are disclosed in U S. Pat. No. 4,078,015.
Harrison, U.S. Pat. No. 4,065,627, discloses a method for preparing acrylic-functional resins from hydroxyalkyl dicarboxylic acid ester, acrylamide, and formaldehyde. Disadvantages in the preparation of these derivatives are again the need for water-immiscible solvents and the high temperatures required for reaction. In addition, the N-methylolamide linkage in these materials ##STR1## is expected to be quite sensitive to acid catalyzed hydrolysis.
A further method for preparing acrylic-functional resin systems is taught in U.S. Pat. No. 4,100,047 and involves reaction of a hydroxy-functional acrylate, or a polyether or polyester thereof, with a tetracarboxylic dianhydride.
U.S. Pat. No. 4,134,916, discloses acryloyl derivatives of polyalkoxyalkylamines prepared by the reaction of a polyalkoxyalkylamine with acrylic acid, acrylic ester, or acryloyl chloride at a temperature of from about 150.degree. C. to about 300 .degree. C.
Although it is apparent from the above prior art that it is known to prepare acrylic-functional resin compositions, no method is known for preparing acrylic-functional resins by a simple ring-opening reaction. The acrylamido- and methacrylamido-acylated oligomers of the present invention are novel and they are prepared more easily by Applicant's novel method than related oligomers can be prepared by methods known in the art.

Curable acrylamido oligomer compositions with initiator, and cured products

Minnesota Mining and Manufacturing Company


Displaying art work or thumbnail images representative of movies, television (TV) programs/episodes and other media content is an appealing and often intuitive way of displaying available media content in a media content browser. However, computer displayable cover art is not necessarily available for all titles. For example, an older movie may not have computer displayable cover art because at the time the movie title was made available it was not anticipated that the movie title might be selectable through a media browser. After considering this description one will understand how the features of various implementations are configured to enable various systems, methods and devices to create computer displayable cover art or thumbnail images for media titles to be displayed by a media browser.

Displaying art work or thumbnail images representative of movies, television (TV) programs/episodes and other media content is an appealing and often intuitive way of displaying available media content in a media content browser. However, computer displayable cover art is not necessarily available for all titles. For example, an older movie may not have computer displayable cover art because at the time the movie title was made available it was not anticipated that the movie title might be selectable through a media browser.
Prior solutions to this problem are ad hoc and burden the end user. For example, one possible solution is to allow a user to supply cover art or a thumbnail image for titles lacking cover art. In other words, the user is forced to become a curator for the content that the user is attempting to sort through in order to identify media content to view or listen to. This task is wholly inconvenient for users that merely want to find media content to view or listen to. Moreover, the task can become extraordinarily burdensome when the user is attempting to search through large libraries of media content.

This patent is subject to a terminal disclaimer.


Systems and methods to generate artificial intelligence models with synthetic data are disclosed. An example system includes a deep neural network (DNN) generator to generate a first DNN model using first real data. The example system includes a synthetic data generator to generate first synthetic data from the first real data, the first synthetic data to be used by the DNN generator to generate a second DNN model. The example system includes an evaluator to evaluate performance of the first and second DNN models to determine whether to generate second synthetic data. The example system includes a synthetic data aggregator to aggregate third synthetic data and fourth synthetic data from a plurality of sites to form a synthetic data set. The example system includes an artificial intelligence model deployment processor to deploy an artificial intelligence model trained and tested using the synthetic data set.

A variety of economy, technological, and administrative hurdles challenge healthcare facilities, such as hospitals, clinics, doctors' offices, etc., to provide quality care to patients. Economic drivers, less skilled staff, fewer staff, complicated equipment, and emerging accreditation for controlling and standardizing radiation exposure dose usage across a healthcare enterprise create difficulties for effective management and use of imaging and information systems for examination, diagnosis, and treatment of patients.
Healthcare provider consolidations create geographically distributed hospital networks in which physical contact with systems is too costly. At the same time, referring physicians want more direct access to supporting data in reports along with better channels for collaboration. Physicians have more patients, less time, and are inundated with huge amounts of data, and they are eager for assistance. However, large datasets are necessary for computer-driven solutions, such as neural networks and other "artificial intelligence" to assist human clinicians with analysis, optimization, improvement, and/or other decision support. Such large datasets are often missing or unobtainable with current systems and restrictions.

Scalable artificial intelligence model generation systems and methods for healthcare


A method and system for detecting an event from a social stream. The method includes the steps of: receiving a social stream from a social network, where the social stream includes at least one object and the object includes a text, sender information of the text, and recipient information of the text; assigning said object to a cluster based on a similarity value between the object and the clusters; monitoring changes in at least one of the clusters; and triggering an alarm when the changes in at least one of the clusters exceed a first threshold value, where at least one of the steps is carried out using a computer device.

1. Field of the Invention
The present invention relates to event mining and, more particularly, detecting new events from a social stream.
2. Description of Related Art
The problem of text mining has been widely studied in the information retrieval community because of the ubiquity of text data availability in a wide variety of scenarios such as the web, social networks, news feeds and many others. Much of the text data arises in the context of temporal applications such as news feeds and social network streams, in which the text arrives as a continuous and massive stream of documents. Streaming applications present a special challenge to such problems because of the fact that it is often necessary to process the data in a single pass and one cannot store all the data on disk for re-processing.
An important problem in the context of temporal and streaming text data is that of online event detection, which is closely related to the problem of topic detection and tracking. This problem is also closely related to stream partitioning, and attempts to determine new topical trends in the text stream and their significant evolution. The idea is that important and newsworthy events in real life (such as the recent unrest in the middle east) are often captured in the form of temporal bursts of closely related documents in a social stream. The problem can be proposed in both the supervised and unsupervised scenarios. In the unsupervised case, it is assumed that no training data is available in order to direct the event detection process of the stream. In the supervised case, prior data about events is available in order to guide the event detection process.

International Business Machines Corporation


The invention is a kayak cockpit cover which is complementary to a channel formed in the kayak deck at the cockpit perimeter. The cover has a conventional closure around the kayak paddler's waist and a planar covering section spanning the cockpit opening. An edge assembly at the outer margin of the covering section includes a doubled section of fabric forming an endless sleeve around the cover, an endless resilient inflatable tube carried inside the sleeve, and a valve integral with the tube. A core element within the inflatable tube aids in manipulation of the edge assembly and fixes its length. When the edge assembly is inserted into the channel around the cockpit perimeter and the resilient tube is inflated, a watertight seal is formed as the expansion of the tube presses the skirt edge fabric against the channel interior wall, while the bulk of the inflated tube secures the cover edge to the kayak deck.

This invention provides an improved kayak cockpit cover for sealing the cockpit in a kayak of the type having a closed deck with a cockpit opening which accommodates a sitting or kneeling paddler. While the invention relates to kayaks of all types, it is particularly suited to "squirt" kayaks, which are very low volume whitewater kayaks that are designed to be fully submerged at times to experience subsurface currents and turbulence in rivers and streams. Because squirt kayaks have a very low volume and minimal buoyancy, an efficient cockpit seal is a matter of great concern, as even a small amount of water in the boat can affect trim, performance and safety.
A cockpit cover or spray skirt is commonly used to seal the cockpit opening around a kayak paddler so that water will not enter the boat while it is navigated through turbulent water conditions. The cover will generally include a fitted waist closure which seals around the paddler's waist, an adjoining planar section of waterproof fabric covering the cockpit opening, and an elasticized edge on the outside of the planar section which engages a raised rim that is formed as a part of the boat deck. Whitewater kayak cockpits are generally oval-shaped, and most cockpit rims are of the type having a slight vertical projection above the deck and an outward-extending lip which retains the edge of the spray skirt. A typical kayak cockpit cover is shown in U.S. Pat. No. 4,583,480.
The prior art spray skirts, retained on a conventional kayak rim by the tension of an elasticized skirt edge have several inherent deficiencies. First is the problem of water leakage between the skirt and rim, especially under extreme conditions. Water will leak into the kayak where the skirt fabric is not in firm contact with the rim. An area of potential leakage is created where the skirt material becomes bunched or puckered because of the circumferential elastic tension. Also, any discontinuity or deterioration in the elastic material retaining the skirt can cause the skirt to leak. In addition, the area of the seal between the skirt and the rim will be subject to shifts and changes in contact pressure due to the movement of the boater in the boat, and leaking may occur when the cockpit is exposed to large waves or submerged in strong currents.
A second problem with use of the prior art kayak skirt and rim is that kayak design possibilities are restricted. A conventional kayak rim must be circular or oval in shape so that the circumferential pressure of the stretched elastic skirt edge will be evenly distributed. A rim shape using a compound curve or an inside curvature will cause an area of non-contact between the skirt and rim, since the elastic edge of the skirt will follow the shortest distance around rim and bridge across the inside curve. This limitation has been encountered in the design of squirt kayaks where use of a narrow elongated cockpit design can provide increased emergency escapability and boater comfort. Squirt boats are susceptible to underwater pinning, and the elongated cockpit design could avoid entrapment of the paddler's lower legs and allow emergency egress from a submerged kayak. In addition, the fabric cover of an elongated cockpit will provide an area within the confines of the boat where the paddler's feet and legs can be moved while the paddler remains seated. An elongated cockpit design is not practical using the prior art, and many other design possibilities are similarly precluded by the prior art limitations.
A third deficiency which arises from the use of a raised cockpit rim and conventional spray skirt is that the rim itself will interfere with water flowing over the deck of the kayak. This is another matter of particular applicability to squirt kayaks in which it is desireable to have maximum maneuverability while the boat is briefly submerged. An uninterrupted deck surface will provide greater stability as the boat is guided through turbulent water conditions.
Accordingly, an important object of the present invention is to provide a kayak cockpit cover or spray skirt and method of installation which will attain a much higher waterproofing standard than the kayak cockpit covers of the prior art secured by an elastic edge to a raised rim.
Another important object of this invention is to provide a cockpit cover which can be adapted to cockpit shapes and deck configurations other than the flat oval cockpit opening necessitated by use of a conventional spray skirt held in place by circumferential elastic tension.
Still another object of the invention is to provide a cockpit opening and cockpit cover which are nearly flush with the adjacent deck surface and which will allow the kayak to be more hydrodynamically stable when submerged in strong river currents.


A method for preparing thermo-crosslinkable and/or thermoplastic elastomer blends by mixing the elastomer with plasticizer oil and other additives, said method comprising the steps of:. (a) continuously premixing the crushed elastomer in an annular zone mixer with at least part of said plasticizer oil, and optionally with at least part of said other additives, to form a preblend in which said elastomer is decomposed and said additives are embedded in the polymer matrix; PA1 (b) completing the mixing of said premix, and optionally of the remainder of said additives, in a mixing unit working batchwise or continuously.. and thereafter

The preparation of thermo-crosslinkable and/or thermoplastic elastomer blends, in particular of vulcanizable rubber blends, can be effected batchwise or continuously, for example on a calender or in an internal mixer. In both cases, the duration of the mixing process is important, so that only moderate throughputs can be obtained.
However, the use of an internal mixer has the disadvantage that, due to the applied speed of rotation, the crude rubber blend is so strongly heated that for many mixture formulations no crosslinking reagents can be added. Therefore, it is often necessary either
to arrange a calender downstream of said internal mixer and to add sulfur and accelerators to the crude blend removed from the internal mixer on said calender only;
or alternatively
to prepare a preblend without sulfur and accelerator in a first mixing passage through said internal mixer, and thereafter to prepare the final blend with addition of sulfur and accelerator in a second mixing passage through said internal mixer.
So far, the attempts for achieving a continuous mixing in mixing extruders has failed for the abovementioned compulsion of observing this order. Calculations show that a spindle length of the order of 40 times diameter would be necessary (D being the spindle diameter). This is technically difficult to realize and economically unattractive.
Furthermore, the use of plasticized elastomers or the addition of large quantities of plasticizers is critical since the shearing forces produceable in the mixture are no longer sufficient for a regular mixing.

Method for continuously preparing thermo-crosslinkable and/or thermoplastic elastomer blends


In a turbomolecular pump, the blade angle of each of rotor blades relative to the plane of a rotor gradually decreases from its base toward its outer most periphery, and the opening ratio and relative blade interval of said rotor blades are made substantially constant from the base of the rotor blade to the outer most periphery of said rotor blade.

The present invention relates to a turbomolecular pump, and more particularly to rotor blades of a "turbomolecular" pump.
In a conventional turbomolecular pump, such as shown in FIG. 5, a plurality of stator blades 2 are axially disposed on the inner wall surface of a substantially cylindrically shaped casing 1. A rotor 3 is mounted inside the stator blades. A plurality of rotor blades 4 are arranged regularly alternately with the stator blades 2 on the outer wall surface of the rotor 3.
The rotor 3 is held by magnetic bearing means comprised of an axial electromagnet 6 and a radial electromagnet 7 provided on a hollow stator column 5. The rotor 3 is held floated radially and axially by the magnetic bearing means.
The stator column 5 is further equipped with a radio frequency motor 8 to rotate the rotor 3. The axial position and the radial position of the rotor 3 are detected by sensors 9 and 10, respectively. Protective dry bearings 11 and 12 are mounted over and under respectively, the stator column 5 to prevent the magnetic bearing from colliding against the rotor 3 when the magnetic bearing is suddenly de-energized due to power failure or malfunctions of the control circuit.
The rotor 3 is rotated at a high speed to induce streams of gaseous molecules between the successive stator blades 2 and rotor blades 4 to obtain an ultra high vacuum.
In a turbomolecular pump of the type described above, the rotor 3 has slotted rotor discs to form rotor blades 4 as shown in FIG. 6 and FIG. 7. The rotor blades are inclined relative to the plane of the rotor 3 with an optimum blade angle .alpha. as shown in FIG. 8 which is constant from the base to the outermost end of the rotor blade 4. The pumping speed is determined by parameters such as opening ratio .epsilon., relative blade interval .lambda., and the relative speed of gaseous molecules with respect to the revolution speed of the rotor blades, wherein, referring to FIG. 4, the opening ratio .epsilon. is defined by S1/(S1+G), and the relative blade interval .lambda. is defined by S2/b.
In a conventional turbomolecular pump, only one rotor blade angle which is optimum at one point along the radial length of a rotor blade is selected. Rotor blades are then formed with this constant rotor blade angle. Since the blade angle is constant, the above parameters change along the rotor blade depending upon the distance from the center of the rotor 3. Even though the blade angle and the parameters are optimum at one point along the rotor blade, they are not optimum at other points, e.g. near the base or the outermost end of the blade. Therefore, the uniform blade angle does not produce an optimum pumping speed along the whole length of the rotor blades.