Peptide derivatives useful as inhibitors of activity of thyrotropin-releasing hormone-degrading ectoenzyme (TRH-DE) are of formula Ia:

TRH has the structure:

The nomenclature of Schechter and Berger (27) is used to describe the positions of the peptide substrate residues (P) relative to the scissile P1—P1′ bond and the corresponding subsets (S) in the active site of the enzyme. In other literature, the right portion of the molecule is called the "prolineamide" or "C-terminal" portion; the centre portion of the molecule is called the "histidyl" portion; and the left portion of the molecule is called the "pyroglutamyl", "COOH-terminal" or "N-terminal" portion.
TRH was the first hypothalamic regulatory hormone to be characterised and as such plays a central role in regulating the pituitary-thyroid axis. In addition, TRH displays a broad spectrum of stimulatory CNS actions that are independent of the hypothalamic-pituitary-thyroid axis (5-7) and it is also now believed to function as a neurotransmitter and/or neuromodulator within the central nervous system (CNS) (5,6). Based on its CNS-mediated effects, TRH has been shown to have potential use in the treatment of brain and spinal injury and certain CNS disorders including cognitive deficits, epilepsy, and shock (7,8). The mechanisms by which TRH improves these clinical conditions are not yet clear but appear to be mediated, in part, by various other neurotransmitter systems (7,8). The full extent of the potential clinical usefulness of TRH cannot be realised until its functions in the CNS are entirely understood.
Unfortunately, the therapeutic efficacy of TRH is limited by its susceptibility to enzymatic degradation (8). Current evidence strongly indicates that TRH-DE is the principal enzyme responsible for the degradation of neuronally released TRH (9, 10-12). TRH-DE is located on synaptosomal membranes in the central nervous system (CNS) (13,14) and thus, it is strategically placed to play a significant role in controlling TRH signals within the CNS, much like that of acetylcholinesterase in regulating the neurotransmitter actions of acetylcholine. TRH-DE is the only ectoenzyme known to degrade TRH (15) and has been shown to exhibit a remarkably high specificity for TRH. Thus, TRH-DE appears to be an exceptional example of a neuropeptide-specific peptidase (16).
In general, potent and selective enzyme inhibitors are required for establishing the exact role of a particular enzyme and are also powerful tools for investigating the biological functions of the enzyme's substrate. In addition to providing valuable insights into the functional roles of enzymes and their substrates, enzyme inhibitors may be used therapeutically to enhance the clinical effects of an enzyme's substrate either by (a) potentiating the endogenous levels of the substrate and/or by (b) protecting endogenously administered substrate from degradation.
Thus, compounds that potently and selectively inhibit TRH-DE could be used to determine the role of TRH-DE in regulating TRH signals. Because TRH-DE displays a strict specificity for TRH, administration of TRH-DE inhibitors should only affect TRH'S neurotransmitter and/or neuromodulator actions. Therefore, TRH-DE inhibitors would also be particularly attractive for investigating the actions of TRH in the CNS. Furthermore, this exclusivity may offer a therapeutic advantage in cases where TRH-DE inhibitors are used to potentiate TRH's CNS actions. The design of TRH-DE inhibitors, however, is made difficult by TRH-DE's restricted specificity and by the lack of a 3D-structure for TRH-DE.
U.S. Pat. No. 4,608,365 Engel describes a treatment for the amelioration of symptoms of amyotrophic lateral sclerosis and other conditions which result from dysfunction of lower or upper motor neurons by the administration of doses of thyrotropin-releasing hormone by intravenous infusion or subcutaneous injection.
Specificity studies thus far indicate that TRH-DE substrates require a five-membered pyrrolidinone, thiazolidinone or butyrolactone ring in the P1 position (4,17). In addition, several studies indicate that TRH-DE specificity is restricted to tri- or tetra-peptides containing the sequence Glp-His and that the presence of a histidine residue in the P1′ position is essential for TRH-DE activity (2,4,18-20). Recently, the inventor was the first to publish the observation that the naturally occurring TRH-like peptide Glp-Phe-ProNH2 is also a substrate for TRH-DE whereas Glp-Glu-ProNH2 is not (21). This finding has since been confirmed by Gallagher et al. (22). To date, no reports of other TRH-like peptides, with the general structure Glp-X-ProNH2, acting as substrates or inhibitors of TRH-DE have been published.
Some tolerance in the P2′ position is suggested by the observations that both pyroglutamyl-histidyl-prolyl-β-naphthylamnide (Glp-His-ProβNA) and pyroglutamyl-histidyl-prolylamido-4-methyl coumarin (Glp-His-ProAMC) are substrates for TRH-DE (4, 20, 22, 23). Glp-His-Trp is hydrolysed by TRH-DE (18) and substitution of the Pro residue in Glp-His-ProβNA by Ala or Trp does not appear to reduce turnover (4).
TRH and the C-terminally amidated peptides Glp-His-Pro-GlyNE2 and Glp-His-GlyNH2, have all been found to have lower Ki values than their corresponding acids when examined as competitive substrates (24, 19, 22) leading to the suggestion that TRH-DE prefers an amide group at the carboxyl-terminus of peptide substrates (22). In addition, because the Km value observed for Glp-His-ProAMC was approximately ten times less than that for Glp-His-ProNH2 Gallagher et al. (22) have proposed that TRH-DE has a preference for large hydrophobic groups at the carboxyl-terminus of substrates. On the contrary, using compounds present in this application, the inventor has now discovered that the addition of a large hydrophobic group to the C-terminus of TRH and TRH-like peptides causes a reduction in both the catalytic rate of hydrolysis and the specificity constant and that this is a useful feature to incorporate into an inhibitor not a substrate.
Only a few inhibitors have been synthesised that exhibit a significant effect on TRH-DE activity and none of these have been shown to be sufficiently effective for pharmacological studies in vivo (11,25). The most potent of these is N-[1(R,S)-carboxy-2-phenylethyl]-N-imidazole benzyl-histidyl β-naphthylamide (CPHNA) (26). Because CPHNA is not a TRH-DE substrate analogue, the specificity of the interactions of CPHNA with TRH-DE has been questioned (11). Nevertheless, CPHNA appears to reversibly inhibit TRH-DE with an inhibition constant (Ki) of 8 μM and to increase the recovery of TRH released from rat brain slices (26). These results indicate that TRH-DE inhibitors can be used to increase local TRH concentrations and that it may be possible to modulate TRH function in vivo via inhibition of TRH-DE activity.
U.S. Pat. No. 4,906,614 Giertz et al. describes a method of preventing or treating posttraumatic nervous injuries by administering a compound of the formula:
wherein R1 is hydrogen, a lower alkyl group, cyclohexyl or benzyl; Z is one of the groups
if Z is a group (a), R2 and R3 together represent an additional bond between the carbon atoms bearing them, or if Z represents a group (b), R3 is hydrogen; R4 is hydrogen or lower alkyl; R5 is hydrogen, lower alkyl or phenyl, R6 is hydrogen or methyl.
U.S. Pat. No. 5,244,884 Spatola et al. describes thionated analogues of thyrotropin releasing hormone, having the formula:
wherein,
Q, W, X and Y, same or different, are oxygen or sulphur, with the proviso that at least one of Q, W, X and Y is always sulphur;
Z is lower alkyl or (4-imidazolyl)methyl; and the pharmaceutically acceptable salts thereof. The disclosed compounds are stated to highly and selectively bind to TRH binding sites in animal tissues, and their utility in treating a variety of diverse physical conditions is disclosed.
U.S. Pat. No. 5,686,420 Faden describes a series of novel thyrotropin-releasing hormone analogs wherein the C-terminal prolineamide moiety has been preserved, the N-terminal moiety comprises one of five different ring structures and the histidyl moiety is substituted with CF3, NO2 or a halogen. A method of use of the analog for the treatment of neurologic disorders in also provided.
The contents of each of the above-mentioned U.S. Patents is incorporated herein by reference.
The present invention relates to compounds that competitively inhibit TRH-DE and display greater apparent binding affinities (i.e. lower Ki values) for TRH-DE than the endogenous substrate, TRH. These compounds have not been reported to occur naturally. Searches carried out after the priority date of this application have revealed that one of the compounds has been named in published papers.
Burt D. R et al., Brain Research, 93 (1975) 309-328 mention pGlu-Asn-ProNH2 as one of 25 analogues of TRH used in tests of inhibition of TRH binding in the cerebral cortex and pituitary.
Bissette G. et al., Neuropharmacology (1978) 17 (45), 229-37 list pGlu-Asn-Pro-NH2 (Abbott 43689) as a TRH analogue used in tests of analeptic effect in mice.
Mazurov A. A. et al., Russian Chemical Bulletin (1998) 47 (10) 19601964 describe the preparation of (inter alia) Glp-Asn-ProNH2 and the measurement of the antidepressant activity of the compound in rats.
Mazurov A. A. et al., Int. J. Peptide Proteins Res. (1993) 42, 14-19 describe the synthesis of Glp-Asn-ProNH2.
Oliver C. et al., Biochem Biophys. Res. Commun. (1978) 84 (4) 1097-1102 refer to pGlu-Asn-Pro-NH2 as one of 30 TRH analogues subjected to enzymic degradation by rat serum or brain homogenate.
None of these papers discloses or suggests the use of Glp-Asn-ProNH2 as an inhibitor of activity of TRH-DE and there is nothing in their teaching to indicate the line of research leading to the present invention.
All of the other compounds of the invention are believed to be novel.

Abstract: wherein:                R1 is an optionally substituted 4-, 5- or 6-membered heterocyclic ring having one or more heteroatoms, in which at least one carbon atom of the ring is substituted with O or S;        X1 is —CO— or —CS— or —CH2CO— or CH(R4) wherein R4 is H or optionally substituted alkyl or —COOH or —COOR11 wherein R11 is optionally substituted alkyl;        X2 and X3 (which may be the same or different) are —CO— or —CS—;        Z is —CH2— or —S— or —O— or —NH—;        Q is O or S;        R2 is H or optionally substituted alkyl or an optionally substituted carbocyclic ring;        R3 is H or optionally substituted alkyl or an optionally substituted mono- or polycyclic ring, optionally having one or more heteroatoms in the ring(s) and optionally being a fused ring; or R2 and R3 together form an optionally substituted mono- or polycyclic ring optionally having one or more heteroatoms in the ring(s) and optionally being a fused ring;        R5 and R6 (which may be the same or different) are H, or lower alkyl;        R7 and R8 (which may be the same or different) are H, or optionally substituted lower alkyl;        R9 and R10 (which may be the same or different) are H, or optionally substituted alkyl, or an optionally substituted carbocyclic ring;        Y is —(CH2)n— where n is 0, 1, 2 or 3 provided that when R2 and R3 form part of the ring n is 0;and pharmaceutically acceptable salts thereof.

The Provost, Fellows and Scholars of the College of the Holy and Undivided Trinity of Queen Elizabeth Near Dublin


Provided is a linear motor actuator which generates a sufficient thrust force and a retaining force and is remarkably smaller than conventional linear motor actuators. The linear motor actuator includes a base member (1) provided with a bottom plate (10) and a pair of side walls (11) and formed in a channel shape; a track rail (2) laid on the bottom plate along a longitudinal direction of the base member; a slide table (3) moving along the track rail; stator magnets (40) arranged on an inner side surface of each of side walls of the base member; and a pair of coil members (41) mounted to the slide table and opposed to the stator magnets provided to each of the side walls of the base member, thereby constituting a linear motor (4).

Conventionally, as linear motor actuators, there are known ones disclosed in JP2004-274950 A and JP2004-312983 A. Each of the linear motor actuators disclosed in those publications includes a track rail which has a bottom plate and a pair of side walls and formed into a channel shape therewith, a slide block incorporated between the pair of side walls of the track rail through intermediation of a plurality of balls, and a linear motor for thrusting the slide block along the track rail.
The linear motor includes stator magnets having magnetic poles of N poles and S poles alternately arranged on a straight line, for generating magnetic fields, and a coil member serving as a mover which is electrified by an alternating current to generate a moving magnetic field along an arrangement direction of the magnetic poles of the stator magnets. The stator magnets are provided on the bottom plate along a longitudinal direction of the track rail. The coil member is mounted to the slide block itself or a table fixed to the slide block, and is opposed to the stator magnets through intermediation of a little gap.
There are coil members of types including and not including a core member formed of a ferromagnetic material such as iron. In view of the level of a generated thrust force, the coil member of the former type is advantageous. The core member is provided with teeth, the number of which is a natural-number multiple of the number of phases of the alternating current, and which are opposed to the stator magnets. A coil is wound around each of those teeth. When the coil is energized, each of the teeth becomes an electromagnet. Between each of the teeth and each of the magnetic poles constituting the stator magnets, there is generated a magnetic attractive force or a magnetic repulsive force with respect to each of the magnetic poles. For example, a three-phase alternating current is formed of three alternating currents of u phase, v phase, and w phase differing in phase from each other by 120 degrees. Accordingly, when the alternating currents differing in phase by 120 degrees are successively allowed to pass through the coil wound around the series of teeth such that the tooth at one end of the core member is supplied with the alternating current of the u phase, the teeth next thereto is supplied with the alternating current of the v phase, and the teeth next thereto is supplied with the alternating current of the w phase, there occurs such a phenomenon that the magnetic field looks as if it moves from the tooth positioned at one end of the core member toward the tooth positioned at another end thereof. This is the above-mentioned moving magnetic field. Owing to cooperation between the moving magnetic field and the stator magnets, a thrust force acts between the mover and the stator magnets.    Patent Document 1: JP 2004-274950 A    Patent Document 2: JP 2004-312983 A


An apparatus conserves oxygen delivered from a supply (28) to a patient through a cannula (44) by providing oxygen delivery selectively in accordance with the physiological requirements and current breathing pattern of the patient. Oxygen flow is set at a prescribed flow rate from the supply by a regulator (30). An oxygen conserving unit (38) includes a controller (64) that operates responsive to timed relationships among pressure signals determined by a fuzzy logic program to deliver oxygen to the patient by opening a valve (72) when a sensed pressure in the patient's nasal passage reaches a threshold level and when the controller determines that the reaching of the threshold is indicative of an inhalation cycle. The controller is further operative to adjust the time period that oxygen is delivered to the patient in accordance with a programmed relation to meet the dynamically changing needs of the patient. The apparatus further includes features which provide fast response, conservation of the energy from a battery power source (86) and both visual and audio indicators (54, 56) to provide indications of alert and alarm conditions. The apparatus further provides control by the user through a single manually actuated switch (52), and mechanical interconnection with the switch and valve to assure continuous flow when the switch is set to a continuous flow setting.

Persons with certain respiratory conditions receive therapeutic benefits from having supplemental oxygen delivered to their respiratory passages while breathing air from the atmosphere. This supplemental oxygen serves to increase the amount of oxygen delivered to the patient's body tissue through the blood stream. This is accomplished because the supplemental oxygen increases the patient's SaO.sub.2 level which is the measure of oxygen saturated hemoglobin in the blood.
The conventional approach to providing supplemental oxygen to a patient is schematically shown in FIG. 1. This prior art system generally designated 10, includes a supply of oxygen 12. In the embodiment shown, the supply is a portable oxygen supply such as a pressurized oxygen bottle. A flow rate controlling regulator 14 is positioned on the supply 12 and is in fluid communication therewith. Regulator 14 may be a pressure compensated regulator of the type known in the prior art which includes an adjustment member 16 thereon. Adjustment member 16 is adjustable to change the rate of flow from the supply into an oxygen delivery line 18. Oxygen delivery line 18 is in fluid communication with a cannula 20. Cannula 20 includes a pair of passages 22 each of which communicates with a nasal passage 24 of a patient which is shown in phantom.
In conventional oxygen therapy the physiological characteristics of the patient are studied to determine a continuous flow rate of supplemental oxygen that proves beneficial to the patient. Regulator 14 is set to deliver this prescribed flow rate by positioning adjustment member 16. The oxygen is continuously delivered at this prescribed flow rate through the cannula 20 to the patient's nasal passages.
A drawback associated with conventional oxygen therapy is that the patient only benefits from the supplemental oxygen during times in the respiratory cycle when the patient is inhaling in a manner which enables the supplemental oxygen to reach the lungs. At other times the supplemental oxygen delivered is of no benefit, and is lost.
Continuous delivery of oxygen presents a drawback when the patient is using a portable oxygen supply with a limited capacity. When oxygen is delivered continuously the time period the patient may use the portable oxygen supply is limited to the capacity of the supply divided by the prescribed flow rate. The capacity available from a reasonably sized oxygen bottle or other supply may not enable a patient to use a single portable supply for as long as would be desirable.
Others have previously developed oxygen conserving devices to extend the time that a patient may receive oxygen before depleting a supply. These prior approaches generally have drawbacks.
Certain oxygen conserving devices attempt to deliver a fixed pulse of oxygen to a patient at the start of inspiration in each respiratory cycle. However, as a patient's activity level increases, the fixed pulse of oxygen may be insufficient to maintain the patient's blood oxygen level. The patient may have a tendency to desaturate, meaning that their SaO.sub.2 level falls below a patient's required oxygen saturation level.
As a patient's exertion level changes, breathing patterns may also change. Prior oxygen conserving devices rely for their beneficial affect on detecting the beginning of a patient's inhalation or inspiration during each respiratory cycle. Because breathing patterns can become irregular, prior devices often fail to properly detect the optimum point in the respiratory cycle for the delivery of the supplemental oxygen. This can result in desaturation of the patient's blood oxygen level because oxygen is being delivered at inappropriate times. Often during irregular breathing prior devices deliver pulses of oxygen at a frequency that is much higher than the actual breathing rate of the patient. Much of the supplemental oxygen can be wasted when the breathing pattern becomes irregular.
Certain previously developed supplemental oxygen delivery devices deliver a burst of oxygen into a patient's nasal passages when a patient begins to inhale. This burst of oxygen is often uncomfortable for the patient. In addition, such high flow pulses generally cannot be tailored to the patient's physiological requirements or dynamically adjusted to meet the needs of the patient's changing activity level or breathing pattern.
Thus, there exists a need for a supplemental oxygen delivery apparatus and method that conserves oxygen while providing the patient with a therapeutic equivalent of continuous oxygen flow, and which overcomes the drawbacks associated with prior conserving devices.

Supplemental oxygen delivery apparatus and method


A microwell plate is described, including a frame 2 that has a frame plate 4 made of a first material having holes 2′, and a vessel 3 formlockingly connected to the frame plate 4 and made from a poly(aliphatic ester)-polycarbonate including soft block ester units, derived from monomers including an alpha, omega C6-20 aliphatic dicarboxylic acid or derivative thereof, a dihydroxyaromatic compound, and a carbonate source.

Microwell plates are used for various microbiological, molecular biological, cellular biological, and immunological procedures. Due to the high number of samples in each microwell plate, the Society of Biomolecular screening and the American National Standards Institute (ANSI) have published standards ANSI/SBS 1-2004 through 4-2004 for microwell plates concerning the particular dimensions and positions of wells or microwells, herein also referred to as vessels, for microwell plates having 96, 984, and 1536 wells. Microwell plates are used in particular for culturing of microorganisms or cells or for the Polymerase Chain Reaction (PCR).
PCR is a process used to amplify and copy a piece of DNA sequence across multiple orders of magnitude and is a vital technique in the field of molecular biology. In the PCR process, the DNA fragment is mixed in aqueous solution with complementary DNA primers and DNA polymerase enzyme and the mixture is taken through several thermal cycling steps. This thermal cycling process separates the double-helix of the target DNA sequence and initiates new DNA synthesis through the DNA polymerase catalyst. A typical thermal profile for the PCR reaction is shown below in Table 1, where ° C. is degrees Celsius.
TABLE 1StepTime DurationTemperature (° C.)Initial Denaturation2minutes94-95Denaturation20-30seconds94-95Primer Extension1minute72Final Extension5-15minutes72
The PCR reactions are typically carried out in microwells in arrays from 8 to 96 wells and volumes of 0.2-0.5 milliliters (mL).
Efficient heat transfer through the walls of the microwell to the reaction solution is required for strict temperature control during the PCR reaction process. In order to achieve efficient heat transfer, the PCR trays are designed with very thin microwell wall thicknesses, such as around 0.2 mm. Injection molding of these thin-wall trays becomes a significant challenge since an extremely high flow material is required to fill the thin microwell walls. In addition, the material needs to have sufficient heat resistance to avoid deformation during the PCR thermal cycling step, and optical clarity is desired so the liquid volume level can be observed. Typically, a polypropylene such as PD702 from LYONDELL BASELL is used for injection molding of the PCR trays. However, polypropylene is subject to softening at elevated temperatures such as those used in PCR denaturation cycles, which can cause PCR or other microfluidic components to become excessively flexible during processing, and/or be subject to warping or other physical deformation, and/or leaking.
Furthermore, single-component microwell plates comprising polypropylene are not particularly suited for being handled by automatic devices because their softness makes it difficult for automatic devices to grip them and their low dimensional stability can have the consequence that the proportioning needles will contact the walls while being introduced into the vessels. Two-component microwell plates comprising a frame plate having a multiplicity of holes made of a first material that is formlockingly connected to a multiplicity of vessels (i.e., microwells) made from a second material have been proposed, but the second material must still meet the above-described challenges.

This patent is subject to a terminal disclaimer.


When a subscriber record is moved from a first HLR to a second HLR that utilizes a different protocol, the wireless communication system sends two queries for location information for the mobile station, one to the first HLR and one to the second HLR, simultaneously. Two responses are received, one from each of the HLRs. The valid response is recorded in a separate table for future use. The invalid response is discarded. The next time a call comes in for the mobile station, the table is traversed to determine if the HLR has been updated for the mobile station. If so, the location request is sent only to the system in the table. If the table does not include information for the called mobile station, simultaneous queries are sent to the first and second HLRs.

Mobile users are typically registered with a home wireless communication system. The home wireless communication system includes a database that contains all the subscribers within the home service area of the home wireless communication system. This database is commonly referred to as a Home Location Register (HLR).
HLRs are capable of conversing in a particular protocol. In typical wireless communication systems, an HLR is only capable of conversing in a single protocol.
Cellular service providers allow mobile users to cross between systems using different protocols. However, HLRs will typically converse in one protocol and ignore messages in any other protocol. This can lead to problems when a mobile user roams from their home coverage area to a coverage area that utilizes a different protocol than their home wireless communication system. This can make determining the location of a mobile station or the delivery of calls to a mobile station difficult or impossible.
Wireless service providers have occasion to move subscriber records from a first HLR to a second HLR that converses in a different protocol than the first protocol. When a call request is received for the mobile station, the wireless communication system requests location information relating to the called mobile station from the first HLR. If the subscriber record is not found in the first HLR because it has been moved, the HLR sends a return error message. The return error message will typically include an unassigned directory number for the called mobile station.
The wireless communication system then sends a location request for the called mobile station to the second HLR. If the second HLR includes a subscriber record for the called mobile station, the wireless communication system utilizes the information from the second HLR.
One problem with this scenario is that the information obtained is not remembered by the wireless communication system. Every time a call for a mobile station is received the same, processor-intensive processing occurs.
Therefore, a need exists for a method that allows a service provider to move subscriber records from one HLR to another that utilizes a different protocol without wasting system resources each time a call is received for the moved mobile station. Further, a need exists for a method that allows a wireless communication system to return location information relating to a mobile station whose subscriber record has been moved in a shorter amount of time.

Method for optimizing home location register queries in a wireless communication system


Aspects of the invention can provide a display apparatus that displays one image plane using plural projection type image display devices. The plural projection type image display devices that together form the display apparatus can be disposed in such a manner that at most one projection type image display device among the plural projection type image display devices forms a projection region of an original shape of projection on a screen.

Aspects of the present invention can relate to a display apparatus that generates a high-luminance and high-resolution image using plural projection type image display devices, and to an image information generating method adapted to the display apparatus. Related art projection type image display devices, such as a projector, have been receiving attention in recent years. The projection type image display device can be characterized by its high degree of freedom in display, such as a large display screen, the brightness of the display screen, and the ability to display an image on a curved surface. For example, it is possible to use plural projection type image display devices, so that projected images from the respective projection type image display devices are superimposed on a screen. This consequently enables a high-definition image to be formed on a larger screen.
Related art techniques to superimpose images on the screen using plural projection type image display devices are roughly divided into three types: "tiling projection", "stack projection", and the combination of these two types. The tiling projection can be chiefly characterized by the capability of generating an image on a screen can be luminance and resolution that become larger and higher in roughly proportion to the number of projection type image display devices used. The tiling projection, however, has problems as follows. That is, the image quality is deteriorated because joined portions are noticeable, colors become irregular due to individual differences of the projection type image display devices used, and further, it is difficult to display images at high definition while maintaining time synchronization.
Meanwhile, the stack projection can be chiefly characterized by its capability of generating a high-luminance image. The stack projection, however, also has problems as follows. That is, it is difficult to generate a high-resolution image, and precise position control is required. In addition, as with the tiling projection, it is difficult to display images at high definition while maintaining time synchronization.
The combination of the tiling projection and the stack projection has the characteristics and problems as described above. Although the combination of the tiling projection and the stack projection is not used as often as the tiling projection or stack projection alone, one example is disclosed, for example, in JP-A-2000-184317.
FIG. 20 is a view schematically showing the configuration of the example disclosed in the cited document. The example can include plural high-luminance and high-resolution projection type image display devices PJa, PJb, and PJc each covering an assigned projection region and a low-luminance and low-resolution projection type display device PJd covering the entire screen as a projection region.
Incidentally, projection regions formed on the screen by the individual projection type image display devices are essentially of a rectangular shape in any of the tiling projection, the stack projection, and the combination of the two types. This is because most of normally used projection type image display devices have rectangular projection regions.
When one image plane is formed using a combination of the projection type image display devices each having a rectangular projection region, it is preferable that the projection region formed by the projection type image display device is projected in a rectangular shape, which is the original shape of the projection region of the projection type image display device, or in a shape closer to the original shape.
Hence, in the projection mode in the related art using any of the tiling projection, the stack projection, and the combination of the two types, it is normal that a projection region from each of the projection type image display devices forming the apparatus is of a rectangular shape. In the cited document, too, the projection regions formed on the screen by the respective projection type image display devices are of a rectangular shape.
By specifying the projection regions from the respective projection type image display devices to be of a rectangular shape, which is the original shape of the projection region of the individual projection type image display devices, it is possible to achieve an advantage that values allocated to individual pixels of the respective projection type image display devices can be readily computed. In exchange, however, there is a problem that moiré (interference fringes) occurs particularly in a superimposed portion.
When projection regions of an original rectangular shape are superimposed intact, because pixels aligned in the form of a tetragonal lattice have the same size and periodic arrangement, interferences of pixels with respect to one another that gives rise to moiré are thought to occur readily.

Display apparatus and image information generating method adapted to display apparatus


The instant invention concerns processes for the production of pyrrole-2-carbonitriles such as 1-methylpyrrole-2-carbonitrile. Such processes preferably comprise the steps of reacting a pyrrole with chlorosulfonyl isocyanate in the presence of a solvent and contacting the resulting product with a molar excess of an amide such as N,N-dimethylformamide. The product of this contacting step is then contacted with a molar excess of an organic base to produce a precipitate and a solution phase. The precipitate is then separated from the solution phase and the corresponding pyrrole-2-carbonitrile is isolated from the resulting solution phase.

Pyrrole-2-carbonitriles are useful as intermediates in the production of chemical compounds, including pharmaceutical and insecticide compositions. See, for example, U.S. Pat. No. 6,492,402 (directed to thrombin inhibitors) and U.S. Pat. No. 5,204,332 (directed to pyrrole carbonitrile insecticidal, acaricidal and molluscicidal agents).
Barnett, et al., J. Can. Chem. 1980, 58, 409, teaches a synthetic process for 1-methylpyrrole-2-carbonitrile involving the reaction of 1-methylpyrrole with chlorosulfonyl isocyanate in dichloromethane in a first step. In Barnett's process, the product of the first step was reacted with DMF, and the reaction mixture was then poured into ice-cold 4M HCl. Following product workup and vacuum distillation, 1-methylpyrrole-2-carbonitile was said to be obtained in 58% yield.
Other synthetic methods for 1-methylpyrrole-2-carbonitrile from 1-methylpyrrole are said to include reaction with methanolic cyanide solution under anoidic oxidation conditions (J. Am. Chem. Soc. 1977, 99, 6111), reaction with excess 1,4-dicyanobenzene as a photosensitizer in the presence of methanolic cyanide solution (J. Chem. Soc., Chem. Commun. 1978, 1108), reaction of trimethylsilyl cyanide in a tetraphenylphorphine-sensitized photooxidation at −70° C. (J. Am. Chem. Soc. 1985, 107, 5279), and reaction with freshly prepared Ph3P(SCN)2 at −40° C. (J. Chem. Soc., Perkin Trans. I 1980, 1132). Another synthetic process starts with 2-pyrrolecarboxaldehyde (Can. J. Chem. 1959, 37, 2053 and J. Chem. Soc., Chem. Commun. 1972, 1226). Yet another process uses 2-pyrrolecarboxaldehyde as the starting material (J. Prakt. Chem. 1994, 336, 467 and Tetrahedron Lett. 1993, 34, 141). Such processes require tedious aqueous workup and repetitive extractions with ether, methylene chloride, or some other suitable solvent. Some procedures require the use of chromatography in the isolation/purification step.


The present invention provides a method for manufacturing a semiconductor device, comprising the steps of preparing a substrate having a quartz support substrate and a silicon layer, forming a base or substrate silicon oxide film over the entire upper surface of the silicon layer, forming a silicon nitride film over the entire upper surface of the substrate silicon oxide film by a plasma CVD method, patterning the silicon nitride film thereby to form a mask pattern having a circumferential exposure portion that exposes the substrate silicon oxide film in a circumferential area, a first opening pattern that exposes the substrate silicon oxide film in an element isolation area, and a second opening pattern that exposes the substrate silicon oxide film within a peripheral area, and thermally oxidizing the substrate using the mask pattern as a mask thereby to form an element isolation structure portion in the element isolation area.

The present invention relates to a method for manufacturing semiconductor devices each element-separated by a so-called field oxide film.
There has been known an example wherein a so-called SOQ (Silicon On Quartz) substrate in which a support substrate is of an insulative quartz support substrate, is used to obtain a semiconductor device having excellent characteristics such as high frequency characteristics and radiation-proof characteristics.
In a thermal oxidation step for forming a field oxide film using a LOCOS (Local Oxidation of Silicon) method, a mask pattern obtained by patterning a silicon nitride film is used in such an SOQ substrate.
The formation of the silicon nitride film is generally performed by an LP-CVD (Low Pressure Chemical Vapor Deposition) method performed at low pressure.
There has been known, for example, a configuration wherein in a semiconductor device manufacturing method in which element or device isolation is done by means of a field oxide film, a mask pattern applied to a LOCOS method, i.e., a thermal oxidation step is formed of a silicon nitride film formed by a CVD method with a view of preventing undesired thinning of an element isolation area or region due to an etching step (refer to a patent document 1 (Japanese Patent Publication Laid Open Number 2005-353745)).
It has been known that the mask pattern obtained by patterning the silicon nitride film formed by the LP-CVD method in particular, which is used in such a thermal oxidation step, produces extremely large tensile stress of 1 GPa (Giga pascal) to 2 GPa over a full range from room temperature (low temperature.) to about 800° C. (high temperature) at which the thermal oxidation step is done.
Problems involved in the related art will now be explained with reference to FIG. 5.
FIG. 5 is a photographic diagram for explaining the related art. The drawing shows a stacked or laminated structure in which a base or substrate silicon oxide film 134 and a silicon nitride film 140′ are laminated on an SOQ substrate 120 in this order.
Described concretely, an SOQ substrate is prepared in which a silicon layer 130 having a thickness of 100 nm is laminated on a quartz support plate 120 having a thickness of 625 μm.
Next, a laminated structure is obtained in which a substrate silicon oxide film 134 having a thickness of 160 nm is formed, and a silicon nitride film 140′ having a thickness of 300 nm is formed on the substrate silicon oxide film 134 by an LP-CVD method.
The so-obtained laminated structure is observed by an SEM (Scanning Electron Microscope).
As shown in FIG. 5, a crack 150 has occurred which extends through (cut longitudinally) the silicon nitride film 140′, the substrate silicon oxide film 134 and the silicon layer 130 and reaches within the thickness of the quartz support substrate 120.
Thus, when the SOQ substrate is used and the silicon nitride film, i.e., the mask pattern for the thermal oxidation step is formed on the SOQ substrate, the quartz support substrate and the thin structure provided on the quartz support substrate may cause cracks due to the tensile stress and the difference between the silicon nitride film and the quartz support substrate in the extent of thermal expansion. As a result, there is at risk of impairing electrical characteristics of a manufactured semiconductor device.
The inventors of the present invention have found out that in forging ahead with extensive investigations, a mask pattern used in a thermal oxidation step in a LOCOS method is formed by a plasma CVD (PE-CVD: Plasma Enhanced Chemical Vapor Deposition) method and the form of the mask pattern is devised thereby to enable the solution of the conventional problems, thus leading to completion of this invention.

Method for manufacturing semiconductor device


A backpack with a receptacle and a tether has been devised whereby the user has a convenient place for the storage and carriage of a weapon, such as an archery bow or a long gun firearm. The backpack has the advantage of allowing the removal of the weapon from the backpack without first removing the pack from the user's back. It is equipped with at least one shoulder strap. In an ideal embodiment, a waist belt is included to facilitate the stabilization of the backpack, as well as to contribute to the load bearing functions of the backpack.

The present invention relates to backpacks. In particular, the present invention relates to a backpack which has the utility of carrying a weapon, such as an archery bow or a long gun firearm, and furthermore allows rapid access to and use of these weapons without removal of the backpack from the user's back. This capability is useful for the activity of hunting, wherein a hunter will often be carrying a backpack filled with the sundries necessary to the outing, and simultaneously carrying an archery bow and/or a long gun. These weapons are often long, bulky, heavy, and awkward to carry, and are an encumbrance to activity. It can readily be imagined that, whereas it is desirable to move quietly while hunting, the physical characteristics of an archery bow or a long gun make this difficult, particularly in the vicinity of brush, tree branches, or the like. Carrying one's firearm or archery bow behind one's body is an advantage, because the body shields the weapon from potential conflicts with passing obstacles. It is further presented that for purposes of safety as well as for the purpose of the protection of valuable weapons while actively hiking while hunting, it is necessary and beneficial to have the weapon carried in a convenient and out of the way location whereby passing branches won't protrude into the sighting mechanism, trigger housing, or other sensitive parts, and also won't be permitted to scratch and mar the finish of the weapon. In the activity of hunting, the participant often wears a backpack for the transport of various articles, and therefore the best potential method for carriage of a firearm or archery bow is on the backpack. There have been attempts to address this desired objective, with varying degrees of success. A common handicap in the prior art is that the mechanisms devised for attaching a weapon to a backpack generally require the removal of the backpack from the wearer's back in order to attach or detach the weapon from its carriage. In hunting, it is frequently necessary to have quick and ready access to one's weapon, and typical backpacks of the prior art do not facilitate this.
There is a long history and variety of backpacks and related devices for carriage of loads upon the human back, and the prior art is widely explored, known, and developed. Their size and dimension ranges from a small, compact variety known as daypacks, such as disclosed in U.S. Pat. No. 5,573,166 to Leja, to larger backpacks designed for carrying heavier and more bulky loads such as disclosed in U.S. Pat. No. 6,179,188 to Gleason. While it is conceivable to strap an archery bow or long gun weapon to these, they are generally not well suited to the task, and a number of specialized straps would in most instances be required.
There is similarly a long and varied history of means and mechanisms for carriage of personal weapons, some of which include some type of backpack-based storage. Most often, a variety of straps are used to attach an archery bow or long gun firearm to the outer surface of a backpack in a removably fixed position, and make no provision for quickly detaching the weapon from the backpack. In fact, most prior art systems require the removal of the pack from the wearer's back to gain access to the weapon, or the assistance of a second person in doing so. It has been discovered in the art that, in order to protect and support the bulk of a compound archery bow, it is helpful to have a pocket on a backpack that cradles the bottom of the bow. Such a backpack is disclosed by U.S. Pat. No. 5,664,721 by Homeyer. This concept bears a limitation in that it does not provide a means for the wearer to get the archery bow off of the backpack without assistance, or without removing the backpack and manipulating a plurality of straps. If used with a long gun firearm, it is meant to be retained on the firearm while it is being fired. It further makes no provision for the carriage of sundry items in a backpack. U.S. Pat. No. 6,431,424 as disclosed by Smith provides a device for carrying a weapon where a user will have access to it, but this device has the disadvantage of placing the weapon forward of the user's shoulders, where it can be an encumbrance to the wearer's activity. U.S. Pat. No. 6,763,987 as disclosed by Eberle provides a long pocket or scabbard for the carriage of a long gun. While excellent in its application, a disadvantage of this configuration is that the dimension of the scabbard often dictates the dimension of the surrounding backpack, resulting in a lack of flexibility in the layout and design of the backpack. Furthermore, a scabbard sized to fit one long gun may not fit another, and a gun-sized scabbard will not be suitable to carry an archery bow. A more universal system, which can be applied to conventional backpacks and which can removably carry a variety of weapons, will in many cases be desirable.
In outdoor activities that involve the use of a weapon, participants frequently range far afield on foot, and often desire to carry an array of goods necessary to the outing in a backpack. These goods can include camping gear, survival equipment, inclement weather gear, water, food, ammunition, and the like. This gear and these backpacks can be quite bulky, and by themselves can be difficult to manage. When carrying a bulky weapon in addition to the backpack, it is advantageous to add it to the load of the backpack rather than carry it separately. It can further be imagined that when climbing hills, passing through thick brush, and the like, the use of both hands is desirable, and that for reasons of safety, convenience, and the relief of fatigue, it is desirable to stow one's weapon in a place that keeps it safe and out of the way, but still maintains it in a ready position in the event that its use is unexpectedly required. It is submitted that the present invention substantially meets these needs, that it is a new, original, and unique departure from the prior art, and that it will be embraced with enthusiasm by those who have reason to carry heavy or bulky weapons while they hike about on their feet.


A microwave filter for use with a microwave brazing system having a brazing chamber, a vacuum line, and a pressure gauge located proximate the vacuum line. The microwave filter includes a baffle plate configured to be mounted in an opening between the brazing chamber and the pressure gauge, and a plurality of hollow pipes configured to substantially prevent the transmission of microwaves from the brazing chamber to the pressure gauge, and further configured to allow gas to flow between the brazing chamber and the vacuum line.

The present invention relates to systems for repairing metal components, such as gas turbine engine components. In particular, the present invention relates to microwave brazing systems for repairing metal components.
Superalloys of nickel, cobalt, and iron, single crystal or equiaxed, are typically employed in gas turbine engine components due to the high mechanical strengths and creep resistances obtained with such alloys. Because gas turbine engine components are exposed to extreme temperatures and pressures, high mechanical strengths and creep resistances are required to preserve the integrity of the engine over the course of operation. However, over time, exposed portions of the components are subject to wear, cracking, and other degradations, which can lead to decreases in operational efficiencies.
Due to economic factors, it is common practice in the aerospace industry to restore turbine engine components rather than replace them. Such restorations desirably restore damaged regions of the engine components to their original dimensions. Engine cracks are typically repaired with brazing operations, which subject the single crystal alloys of the engine components to high temperatures (e.g., 1200° C./2200° F.) for extended durations (e.g., 10 hours). Exposure to the high temperatures for the extended durations, however, reduces the low-temperature (e.g., 815° C.-870° C./1500° F.-1600° F.) creep resistances of the single crystal alloys. This is believed to be due to coarsening of the gamma prime (γ′) phases of the single crystal alloys, which is measurable by increases in the average particle sizes of the γ′ phases. The reduction of the low-temperature creep resistances can cause the alloy structures of the engine components to creep under the applied temperatures and pressures during operation, thereby also reducing operational efficiencies.
One technique for restoring engine components that substantially preserves the low-temperature creep resistances of single crystal alloys involves microwave brazing. Microwave brazing uses microwave-wavelength radiation to melt and fuse a brazing alloy with the base material of the damaged engine component. The microwave brazing process reduces the duration and temperature that the base material is exposed to, thereby substantially preserving the low-temperature creep resistances of the single crystal alloys. A microwave brazing process is typically performed in a brazing chamber under vacuum to provide a uniform braze and to reduce the risk of generating glow discharges and plasmas. However, pressure gauges used to measure the reduced pressure within the brazing chamber are sensitive to the microwaves used in the microwave brazing process. This may provide erroneous pressure measurements during the microwave brazing process, thereby reducing the ability to obtain the desired vacuum environment. As such, there is a need for a system capable of providing accurate pressure measurements during microwave brazing processes.

Microwave filter and microwave brazing system thereof


The present invention relates to a method of processing reaction mixtures obtained from the oxidation reaction of cyclohexane to adipic acid. The processing of the reaction mixture obtained from the direct oxidation of cyclohexane to adipic acid with oxygen, in an organic solvent and in the presence of a catalyst, comprises:. (a) a distillation which makes it possible to separate out, on the one hand, a distillate comprising at least some of the most volatile compounds such as the unconverted cyclohexane, the organic solvent, cyclohexanone, cyclohexanol, cyclohexyl esters, lactones and water, and, on the other hand, the distillation residue comprising the diacids formed and the catalyst; PA1 (b) the addition of water to the distillation residue in order to form an aqueous solution; PA1 (c) crystallization of the adipic acid from the aqueous solution of the distillation residue.

1. Technical Field of the Invention
The present invention relates to a method of oxidation of cyclohexane to adipic acid, and more particularly to the processing of the reaction mixtures obtained from this oxidation reaction.
2. Description of the Prior Art
The direct oxidation of cyclohexane to adipic acid is a process which has been explored for a long time, in particular on account of the obvious advantages there would be in converting the cyclohexane into adipic acid in a single step and without using an oxidizing agent such as nitric acid, since this compound generates nitrogen oxides which need to be processed subsequently in order to avoid pollution.
Patent Application WO-A-94/07833 describes the oxidation of cyclic hydrocarbons into corresponding diacids, in a liquid phase containing a solvent, at a temperature of at least 60.degree. C., using a gas containing oxygen and in the presence of an oxidation catalyst such as a cobalt compound, and points out that the solvent represents less than 1.5 mol per mole of cyclic hydrocarbon, that the said solvent comprises an organic acid having only primary or secondary hydrogen atoms and that the reaction is carried out in the presence of at least 0.002 mol of cobalt-based catalyst per 1,000 g of reaction mixture. At the end of the reaction, the diacid formed is isolated.
Patent Application W0-A-94/07834, filed on the same day as the one above, also describes the same process, but develops the phases of processing the final reaction mixture. This processing consists in separating out the diacid formed, by cooling the reaction mixture in order to cause the said diacid to precipitate out, in separating by filtration the diacid from two liquid phases, a non-polar phase which is recycled, and a polar phase which is also recycled after an optional hydrolysis and separation of an additional amount of diacid.
These patents present solutions which allow the one-step oxidation of cyclohexane to adipic acid with industrially acceptable selectivity, but they provide no solution which is industrially applicable to the processing of the reaction mixture obtained from the oxidation, taking into account the separation of the many different reaction products and side products, unconverted products and the catalyst.

Method of processing reaction mixtures obtained from the oxidation of cyclohexane


A communication system comprising a mobile station and a network implements a persistent packet data control channel that provides for a continuous exchange of control information, such as system information (SI) messages and handoff-related information. The mobile station implements the persistent packet data control channel by mapping the persistent packet data control channel to a packet associated control channel when a packet associated control channel is available and to a virtual associated control channel when a packet associated control channel is not available. The virtual associated control channel allows the mobile station to pass control information to network in the absence of an uplink Temporary Block Flow (TBF).

The General Packet Radio Service (GPRS) and Enhanced Data for Global Evolution (EDGE) protocols for the Global System for Mobile Communication (GSM) have introduced a capability of the user data interchange into mobile wireless products. GPRS, and its superset, EDGE, permit efficient use of radio and network resources when data transmission characteristics are packet-based, intermittent and non-periodic, possibly frequent with small transfers of data, for example, less than 500 octets, or possibly infrequent with large transfers of data, for example, more than several hundred kilobytes. User applications that may utilize GPRS/EDGE protocols may include Internet browsers, electronic mail, file transfers, and other applications involving transfers of data.
FIG. 1 is a block diagram of an exemplary GPRS/EDGE communication system 100. Communication system 100 includes multiple Base Station Systems (BSSs) 110, 120 that each provides communication services to a respective coverage area, or cell. Each BSS 110, 120 includes a respective Base Transceiver Station (BTS) 112, 122 that is coupled to a respective Base Station Controller (BSC) 114, 124. Each BSS 110, 120 is coupled to a Serving GPRS Support Node (SGSN) 128, which SGSN is further coupled to a Gateway GPRS Support Node (GGSN) 130 and, via the GGSN, to an external network 132. BSSs 110, 120, SGSNs 116, 126, and GGSN 130 are collectively referred to as a communication system network 140. Communication system 100 further includes an MS 102 that resides in a coverage area, or cell, serviced by a first, source BSS 110 of the multiple BSSs 110, 120. Source BSS 110 provides communication services to MS 102 via an air interface, or wireless communication link, 104 that includes a downlink and an uplink.
As MS 102 moves around in communication system 100, the MS may experience deterioration in radio frequency (RF) signal conditions or congestion conditions with respect to the communication services provided to the MS by source BSS 110. As a result, the MS 102 may decide to perform a cell reselection. In order to facilitate a selection of a new cell, such as a cell associated with BSS 120, MS 102 and network 140 may exchange System Information (SI) messages and measurement information related to the neighboring cells. However, the system provided by the GPRS/EDGE protocols provides only for a discontinuous exchange of such information. That is, such information is exchanged in data packets in GPRS/EDGE systems via a Packet Associated Control Channel (PACCH). The PACCH is a control channel that comprises blocks of four sequential bursts that are stolen from an associated PDTCH. As a result, the PACCH exists only as a portion of a Temporary Block Flow (TBF) comprising data that is being transferred via the PDTCH. When there is no TBF, for example, when a user of MS 102 is receiving rather than sending, the uplink PACCH goes away.
Originally, GPRS/EDGE communication systems were conceived as means of generating additional revenues for system operators based on their excess capacity during non-peak usage period. User applications were originally envisioned to include Internet browsers, electronic mail, file transfers and other applications for which best efforts data transfer are appropriate. At that time, the industry did not anticipate real-time applications, such as streaming and Push-to-Talk (PTT), making use of GPRS/EDGE as an underlying wireless transport vehicle. As a result and in order to maintain system simplicity, no real-time handover procedure is specified for best effort packet data transfers over GPRS/EDGE. Instead, cell reselection is achieved by allowing MS 102 to reselect cells as it does in idle mode, which causes the MS to abort its packet transfer on one cell and completely re-establish the ongoing packet transfer on the new cell. In the meanwhile, until the packet transfer is re-established on the new cell, all data flows are put on hold. As a result, a reselection between cells typically interrupts the flow of data in both directions for 500 milliseconds (ms) to approximately four seconds if the new cell resides in a same Routing Area (RA) as the old cell, that is, if a target BSS is serviced by a same SGSN as a source BSS. If the new cell resides in a different RA, that is, if the target BSS is serviced by a different SGSN that the source BSS, then the impact is typically 8 seconds.
Current metrics show that in an urban area, cell reselection takes place approximately two to four times per minute, even with the MS physically stationary. The lack of a true synchronized handover for a GPRS/EDGE communication system such as system 100 means that the continuity of both uplink and downlink data is compromised each time a new cell is reselected, either autonomously or under the control of network 140. For applications such as PTT, this means that during a one-way conversation, when either a talker or a listener reselects to a new cell, the listener may lose up to eight seconds of voice information and any associated control information conveyed in association with the voice information.
To overcome these problems of data flow disruptions during cell reselection, a true synchronized handover is being considered for the packet domain. However, the introduction of such a packet domain handover is hindered by the fact that there exists no equivalent in GPRS/EDGE communication systems to a Slow Associated Control Channel (SACCH) of circuit-switched communication systems over which handover measurements, typically pilot signal measurements, may flow during, and between, voice data transfers comprising a single application session, such as PTT.
Therefore, a need exists for a method and apparatus that provides for a persistent flow of control data associated with a packet data traffic channel during, and between, packet data transfers comprising a single application session in a GPRS communication system.

Method and apparatus for transmission of control data in a packet data communication system


In a data communication system a signal is coded with n-bit codewords, wherein n is an integer. The codewords are converted to a serial bit-stream and scrambled using a PRBS (Pseudo-Random Binary Sequence) from a PRBS generator (4). The PRBS sequence has a length n x m where m is an integer. At a receiver the serial data is descrambled using a corresponding binary sequence from a PRBS generator (5) matched to that in the transmitter. The descrambling data is decoded in a decoder (6) in synchronism with the binary sequence in the generator (5), thereby maintaining word alignment between the transmitter and the receiver.

1. Field of the Invention
The present invention relates to the communication of digitally encoded data, and in particular to systems in which the data is scrambled in accordance with a binary sequence before transmission. As described below, the present invention has been found to be particularly advantageous in connection with the encoding of video signals but is also applicable to different forms of data.
2. Related Art and Other Considerations
It has previously been proposed to scramble encoded video data prior to transmission by combining at an XOR gate the outputs of a coder and a PRBS (pseudo-random binary sequence) generator. The scrambled data can then be read only at a receiver having a matching descrambler. The coder may encode the input signal using, for example 5-bit hybrid DPCM (differential pulse code modulation) as described in the paper by M. C. W. Van Buul, "Hybrid D-PCM, A combination of DPCM and PCM", IEEE Trans. on Communications, Vol. COM-26, No. 3, 3/78 pp 362-8. The parallel 5-bit codewords output by such a coder are converted to a serial bit-stream before being scrambled by the pseudo-random code sequence. Then at the receiver the serial data is unscrambled using a matching PRBS generator before being assembled into 5-bit codewords which are decoded to reconstitute the original video signal.
In order to descramble the data correctly it is necessary that the PRBS generator in the receiver should be aligned with that in the transmitter so that corresponding bits in the pseudo-random sequence are applied to the same elements of data in the scrambler and descrambler. As described in the present applicant's earlier British applications numbers 8804552 and 8721603, this is achieved by searching for a video line synchronisation or frame alignment word, or other predetermined fixed component of the received data and aligning the PRBS generator accordingly. While this is sufficient to ensure appropriate descrambling of the serial data it is also necessary to ensure that the conversion of the serial data to parallel 5-bit words is carried out in correct alignment with the transmitter to avoid corruption of the data. This may be achieved by adding extra synchronization bits to the video data but this gives rise to an undesirable overhead in the transmission rate. Alternatively it has been proposed to replace some of the least significant bits of the video signal with synchronization words. This however introduces small but regular errors into the video signal which may be visible when that signal is reconstituted.

Method of synchronizing the pseudo-random binary sequence in a descrambler


The invention includes: powder preparation step of obtaining magnetic core powders by mixing, of magnetic powders with thermosetting resin powders in hot state; powder filling step of filling the obtained magnetic core powders into a die; a compaction step of compacting magnetic core powders; and compact heating step of heating, compacts to the elevated temperature state at which the thermosetting resin hardens after compaction.

1. Field of the Invention
The invention relates to a method of producing a powder magnetic core and to a method of producing a magnetic core powder therefor.
2. Description of Related Art
There are many articles that electromagnetism, e.g., transformers, motors, generators, reactors, speakers, induction heaters, various actuators, and so forth, in our surroundings. For example, the stator core and the rotor core in a motor and the reactor core in a reactor are mostly made from powder magnetic cores made by the compacting of resin-coated soft magnetic powders. Due to this application of a resin film to the particle surfaces, such a soft magnetic metal powder for powder magnetic core fabrication suppresses the appearance of iron losses by establishing insulation for the powder and hence insulation for the powder magnetic core itself.
The methods used to coat magnetic powders can generally be divided into wet methods and dry methods. For example, Japanese Patent Application Publication No. 2008-303443 (JP-A-2008-303443) discloses the production of a powder magnetic core by bringing a soft magnetic powder into contact with a coating treatment solution prepared by dissolving a silicone resin in methanol; thereafter drying the soft magnetic powder to form a silicone resin film on the particle surfaces; and subsequently compacting the soft magnetic powder to form a powder magnetic core. This wet method, which employs a solvent to form a silicone resin film, can form a uniform silicone resin film on the surfaces of the magnetic particles. However, it requires a step of drying off the solvent and also requires the disposition of a vacuum device for degassing and thus inevitably entails increased costs from both a process standpoint and an equipment standpoint. The execution of a continuous magnetic powder coating process is also problematic.
In order to avoid the problems described above for wet methods, attention has focused on powder magnetic core production methods that utilize a dry process that does not employ a solvent. Japanese Patent Application Publication No. 2008-270539 (JP-A-2008-270539) and Japanese Patent Application Publication No. 2009-259939 (JP-A-2009-259939) disclose powder magnetic core production methods including a mixing step, in which a resin powder formed from a thermosetting silicone resin is mixed with a magnetic powder having an insulating film, e.g., a silica film, on the particle surface; a compacting step, in which the mixed powder provided by the mixing step is compacted in hot state; and a heating step, in which the compact provided by the compacting step is heated to a high temperature state at which the silicone resin cures. In addition, the compacting step includes a heating step, in which the mixed powder filled into a die is heated to bring it into hot state; and a compression step, in which the mixed powder, while residing in a state in which the resin powder has been softened due to the heating step, is compacted. This hot state denotes a high temperature environment in which the resin powder does not undergo a complete condensation polymerization. In this Specification, "hot compacting" refers to a method of obtaining a compact via a compacting step in which compacting is performed in hot state temperature environment.
The methods disclosed in JP-A-2008-270539 and JP-A-2009-259939 can produce a powder magnetic core without using a solvent. However, these methods, by their very nature, include just the compacting of a mixture of a resin powder and a soft magnetic powder that has been insulated with a silica film. As a consequence, the role of the resin in the powder magnetic core resides more in strengthening the powder magnetic core through particle-to-particle bonding than in the insulation of the soft magnetic powder. Accordingly, when use is made of a soft magnetic powder that has not been insulated with, e.g., a silica film, it is thought that, for example, large losses will occur without the ability to obtain a thorough coating of the particle surfaces by the resin, and the magnetic properties will decline.
Moreover, a powder magnetic core is fabricated in each of the examples given in JP-A-2008-270539 and JP-A-2009-259939 using not more than 0.3 mass % resin powder with reference to the mixed powder as a whole. It is stated in JP-A-2008-270539 that when the resin powder is incorporated at 0.2 mass %, the compact provided by compacting in hot state can be removed from the die using a low decompacting pressure without producing, for example, galling with the die. The inventors have in fact confirmed that a powder magnetic core having the desired magnetic properties and strength and also free of problems with its appearance is obtained when the resin powder is incorporated at 0.2 mass %.
However, it was also discovered that a powder magnetic core having a normal appearance is not obtained when the same procedure as described in JP-A-2008-270539 or JP-A-2009-259939 is used to produce a powder magnetic core that has a relatively large resin powder content, as is used, for example, in reactor cores. The abnormalities in appearance included, for example, roughening and cracking of the surface of the powder magnetic core, chipping at angles of the powder magnetic core, and lamination. These abnormalities in appearance pose a number of risks; for example, they can lead to breakage, they can prevent use due to their effect on the dimensional accuracy, and, even when they do not have a direct influence on the magnetic properties, they can lower the reliability.
It was further discovered that the filling behavior by the mixed powder is impaired when a mixed powder containing relatively large amounts of resin powder is filled into a die that has been preheated to hot state; for example, the particles may aggregate or coalesce with one another and the resin powder may melt bond to the surface of the die. This impaired filling behavior is thought to be connected to the impaired compacting behavior noted above.

Method of producing powder magnetic core and method of producing magnetic core powder


An apparatus that measures images of at least a portion of an eye and records data sets indicative of a neurological condition. A method of the invention employs a plurality of images, or a plurality of data sets, or at least one image and at least one data set to provide an interpretive result based on the interrelation of the images and data sets, such as by superposition. The apparatus and method thereby provide guidance as to the presence of a medical condition in a patient. The apparatus includes modules that observe images and/or data sets, that analyze the information, and that superpose the information. Modules are provided to store information, to provide data output, to provide reports, and to display information, including superposed images and data. Modules can be provided in hardware, in software, in firmware, or in combinations thereof.

Numerous systems and methods are known for examining states of health of eyes. For example, U.S. Pat. No. 5,065,767, issued Nov. 19, 1991 to Maddess, discloses a psychophysical method for diagnosing glaucoma that employs a time varying contrast pattern. Glaucoma may be indicated for an individual who displays a higher than normal contrast threshold for observing the pattern. Maddess also discloses other tests for glaucoma such as the well-known observation of a scotoma, measurement of intraocular pressure, and assessment of color vision defects. U.S. Pat. No. 5,295,495, issued Mar. 24, 1994 to Maddess, discloses systems and methods for diagnosing glaucoma using an individual's response to horizontally moving stripe patterns, which is known as optokinetic nystagmus (OKN). The spatially varying patterns may also vary temporally. In U.S. Pat. No. 5,539,482, issued Jul. 23, 1996 to James et al., additional systems and methods for diagnosing glaucoma using spatial as well as temporal variations in contrast patterns are disclosed. U.S. Pat. No. 5,912,723, issued Jun. 15, 1999 to Maddess, discloses systems and methods that use a plurality of spatially and temporally varying contrast patterns to improve the methods disclosed in the earlier patents. U.S. Pat. No. 6,315,414, issued Nov. 13, 2001 to Maddess et al., describes systems and methods for making a binocular assessment of possible damage to the optical nerve, optical radiations and white matter of the visual brain indicative of various neurological disorders by measuring responses to visual stimuli.
U.S. Pat. No. 6,068,377, issued May 30, 2000 to McKinnon et al., describes systems and methods for testing for glaucoma using a frequency doubling phenomenon produced by isoluminent color visual stimuli. The disclosure is similar to that of Maddess and co-workers, but uses different, preferably complementary, frequencies of light having the same luminosity as the visual probe signal.
U.S. Pat. Nos. 5,713,353 and 6,113,537 describe systems and methods for testing for blood glucose level using light patterns that vary in intensity, color, rate of flicker, spatial contrast, detail content and or speed. The approach described involves measuring the response of a person to one or more light pattern variations and deducing a blood glucose level by comparing the data to calibration data.
Other disease conditions and their identification are described in a paper by S. Sokol, entitled "The visually evoked cortical potential in the optic nerve and visual pathway disorders," which was published in Electrophysiological testing in diseases of the retina, optic nerve, and visual pathway, edited by G. A. Fishman, published by the American Academy of Ophthalmology, of San Francisco, in 1990, Volume 2, Pages 105-141. An article by Clark Tsai, entitled "Optic Nerve Head and Nerve Fiber Layer in Alzheimer's Disease," which was published in Arch. of Ophthalmology, Vol. 107, February, 1991, states that large diameter neurons are damaged in Alzheimer's disease.
U.S. Pat. No. 5,474,081, issued Dec. 12, 1995 to Livingstone et al., describes systems and methods for determining magnocellular defect and dyslexia by presenting temporally and spatially varying patterns, and detecting visually evoked potentials (VEP) using an electrode assembly in contact with the subject being tested.
U.S. Pat. No. 6,129,682, issued Oct. 10, 2000 to Borchert et al., discloses systems and methods for non-invasively measuring intracranial pressure from measurements of an eye, using an imaging scan of the retina of an eye and a measurement of intraocular pressure. The intraocular pressure is measured by standard ocular tonometry, which is a procedure that generally involves contact with the eye. U.S. Pat. Nos. 5,830,139, 6,120,460, 6,123,668, 6,123,943, 6,312,393 and 6,423,001 describe various systems and methods that involve mechanical contact with an eye in order to perform various tests. Direct physical contact with an eye involves potential discomfort and risk of injury through inadvertent application of force or transfer of harmful chemical or biological material to the eye. Direct physical contact with an eye is also potentially threatening to some patients, especially those who are young or who may not fully understand the test that is being performed.
First Generation FDT Instrument
The Frequency Doubling Technique (hereinafter "FDT") presents back-lit flashed images viewed on a fixed, flat shielded screen in front of a stationary subject. The FDT instrument is similar, but smaller, and the FDT test is substantially shorter in testing duration, as compared to a visual field instrument that tests peripheral and central vision. Visual field testing is standard in all offices providing comprehensive eye exams and treatment of eye disease. The FDT instrument uses sinusoidal grating targets of low spatial frequency (as opposed to simple dots of light in a traditional visual field test). The sinusoidal gratings are reversed (black to white, and white to black) at 25 Hz. The subject perceives the targets as small striped areas in either central or peripheral vision. As with traditional visual field testing, subjects are seated and have the chin and forehead positioned in a stabilizing rest support. Generally, subjects are tested monocularly. They fixate a target directly in front of them and respond by pushing a button each time they see an image flashed anywhere in their visual field. The instrument records and retests areas based on the subject's responses. A computer program operating on a processor calculates reliability based on fixation losses. The entire test takes less than two minutes per eye. The FDT does not require dilation of the subject's eyes. Therefore, it does not impair vision or the ability to function after the test is performed. The test causes no discomfort. The FDT has received approval from the Federal Drug Administration and has been in clinical use for over four years.
There is a need for systems and methods that will provide better information about a larger number of possible conditions using a single testing period, and that will disclose the initial levels of impairment at accuracies that are not presently attainable, while avoiding to the extent possible mechanical contact with the test subject, especially contact with the eye. There is also a need for systems and methods that can be used by non-specialist medical practitioners to screen and evaluate patients without the necessity to first involve a specialist practitioner.

Apparatus and method for diagnosis of optically identifiable ophthalmic conditions


A nitride semiconductor substrate is provided which is suitable for a high withstand voltage power device and prevents a warp and a crack from generating in a Si substrate when forming a thick nitride semiconductor layer on the substrate. A nitride semiconductor substrate 1 is prepared in such a manner that a buffer layer 3 and a semiconductor active layer 4 each comprising a group 13 nitride are stacked one by one on one principal plane of a Si single crystal substrate, the one principal plane has an offset angle of 0.1° to 1° or −1° to −0.1° with respect to a (111) plane, an average dopant concentration in a bulk is 1×1018 to 1×1021 cm−3, the Si single crystal substrate 2 has a SiO2 film on the back, and the total thickness of the buffer layer 3 and the semiconductor active layer 4 is 4 to 10 μm.

1. Field of the Invention
The present invention relates to a nitride semiconductor substrate comprising a group 13 nitride and used suitably for a semiconductor power device which withstands a high voltage.
2. Description of the Related Art
Group 13 nitride semiconductors including GaN attract attention as next-generation semiconductor power device materials. In particular, a nitride semiconductor substrate having grown group 13 nitride semiconductor crystal epitaxially on a substrate of different materials, such as sapphire, silicon, etc., has many advantages in respect of the balance between a device property and manufacturing cost. Especially, one that uses a Si single crystal substrate which allows a diameter of 6 inches is very useful industrially.
However, since a nitride semiconductor has a thermal expansion coefficient larger than that of a Si single crystal, a nitride semiconductor layer epitaxially grown on a Si single crystal substrate at a high temperature may generate a crack, a crystal defect due to difference in crystal-lattice constant from Si when it is cooled to room temperature.
To cope with this, improvements have occurred, such as using a highly concentrated doped Si substrate when depositing a nitride semiconductor layer, preparing a buffer layer on the Si substrate, etc. Further, in order to form a good buffer layer, Japanese Patent Application Publication No. 2003-59948 (Patent Literature 1), for example, has proposed a plane direction is arranged such that the principal plane of the Si single crystal substrate on which a buffer layer is deposited is flush with a (111) plane or inclined at an angle in the range of ±4° to the (111) plane.
Furthermore, Japanese Patent Application Publication No. 2012-15304 (Patent Literature 2) discloses that, in contact with the principal plane of the Si substrate whose principal plane is a plane inclined at an offset angle of 0.1° or less to the (111) plane, an AlN layer whose half-value width of a rocking curve by X-ray diffraction at (002) plane is 2000 sec or less is prepared, on which a GaN type semiconductor layer is provided, whereby crystallinity of the nitride semiconductor can be improved and the property of the semiconductor device can also be improved.
As described in Patent Literature 2 above, it is known that the offset angle of the Si substrate principal plane influences the crystallinity and evenness of the nitride semiconductor layer which is deposited and formed on the principal plane.
Further, Patent Literature 1 above discloses that the plane direction of the Si single crystal substrate and inclination (offset angle) are specified for the purpose of reducing atomic steps on a crystal surface of the buffer layer and a semiconductor region, thus some steps are less problematic in the case where an epitaxial growth layer is comparatively thick,
Incidentally, in recent years, power devices, such as a high-electron mobility transistor (HEMI) element, have been requiring a high withstand voltage, so as to bear even a voltage exceeding 600V. In such a high withstand voltage device, the nitride layer requires the total thickness of greater than 4 μm.
Therefore, in such a thick nitride layer, in order to attain reduction (i.e., improvement in evenness) of the step of the nitride layer surface, it is thought that it is not necessary to employ the Si single crystal substrate with a plane direction in which an offset angle is comparatively small as described above in Patent Literatures 1 and 2.
However, when the nitride layer is thickened as described above, there arises a problem in that the cracks and warp are generated in the nitride semiconductor substrate in the case of epitaxial growth. In particular, the diameter of the substrate has been enlarged for improving the manufacture efficiency in recent years, 6 inch substrates have been manufactured, and it becomes progressively more difficult to control the warp in such a large diameter substrate.
Such problems are conventionally addressed by reducing stress by means of a multilayered buffer layer, by a method of restricting dislocation generation, or by a method of controlling the warp of the whole substrate by controlling impurity concentration of the Si single crystal substrate of a base. However, even in the case where such technology is applied, it is very difficult to restrict the warp in the large diameter substrate.
Then, the present inventors have diligently repeated various examinations of the substrates having the above-described thick buffer layer for high withstand voltage power devices. Thus, we have found that the warp of the nitride semiconductor substrate and generation of cracks can be controlled effectively, while maintaining good crystallinity, by a suitable combination of a specific underside form, a bulk property, and a surface offset angle in the Si single crystal substrate.


A diaphragm unit includes: a plate-like base member having an optical path hole formed therein; diaphragm blades overlapping with each other in an optical axis direction of an optical system, being supported by the base member so as to be movable in directions in which the diaphragm blades approach and depart from the optical axis along a plan perpendicular to the optical axis, and forming a diaphragm opening centered on the optical axis inside the optical path hole; and a driving mechanism adjusting the size of the diaphragm opening by moving the diaphragm blades.

1. Field of the Invention
The present invention relates to a diaphragm unit, a lens barrel, and an imaging apparatus.
2. Description of the Related Art
A diaphragm unit is known which is used in portable imaging apparatuses such as video cameras and digital still cameras or projection-based optical apparatuses such as liquid crystal projectors.
As such a type of diaphragm unit, a diaphragm unit is known which employs an iris diaphragm adjusting the size of a diaphragm opening by swinging plural diaphragm blades arranged around the diaphragm opening in cooperation. A diaphragm unit is also known in which two diaphragm blades are made to slide along a straight line perpendicular to an optical axis with the diaphragm opening interposed therebetween (see JP-A-2001-117133 (Patent Document 1)).

Diaphragm unit, lens barrel, and imaging apparatus


The present invention provides a method for the removal of biofilm, flocculent bulked sludge or bulked biologically active sludge from an aqueous system. The method involves adding one or more chlorinated hydantoins, such as dichloro- or monochlorodialkylhydantoin, to the aqueous system. Alternatively, the chlorinated hydantoin may be formed in situ by adding a chlorine source and an alkylated hydantoin separately to the aqueous system. The invention is particularly advantageous because of the outstanding photostability of the chlorinated hydantoin solutions even when exposed to sunlight.

Biofilm may be defined as an undesirable accumulation of microorganisms on a surface and in flocculent masses. It is estimated that more than 99% of all the planet's bacteria live in biofilm communities. Biofilm consists of cells immobilized in a substratum, frequently embedded in an organic polymer matrix of microbial origin, which can restrict the diffusion of substances and bind antimicrobials. In flowing aquatic environments, a biofilm consists of a sticky and absorptive polysaccharide matrix encompassing microorganisms. Biofilm bacteria are morphologically and metabolically distinct from free-floating bacteria. Their structural organization is a characteristic feature and distinguishes biofilm cultures from conventional planktonic organisms.
Biofilms create problems for industry from corroding water pipes to computer-chip malfunctions. Any man-made device immersed in an aquatic habitat is susceptible to colonization by microbial biofilm. For example, biofilm may be present on the surfaces of ship bottoms, industrial pipelines, household drains, and artificial hip joints. For the industrial manufacturer, biofilm clusters represent a source of microbial inoculation in a system and may cause plugging problems. In water treatment facilities, the formation of suspended biofilm produces a bulked biological sludge which settles poorly and is difficult to compact in the clarification process. Both non-filamentous and filamentous bulk forms are prevalent in which numerous bacteria permeate the floc. In addition to their role as fouling agents, biofilms may also have adverse effects on people, including altering their resistance to antibiotics and affecting the immune system. Thus, there exists a need in the art for developing effective methods of removing biofilm.
The dynamic nature of biofilms makes it difficult to measure and monitor biofouling. Biofilms often include embedded inorganic particles such as sediments, scale deposits, and corrosion deposits. Moreover, biofilms continuously change in thickness, surface distribution, microbial populations and chemical composition, and respond to changes in environmental factors such as water temperature, water chemistry and surface conditions. Thus, the complexity of biofilms has reduced the effectiveness of treatment and removal strategies.
Even though most microorganisms in industrial systems are associated with biofilm, they have historically received less attention than planktonic microorganisms. However, it has been shown that various biocides are less effective against biofilm than dispersed cells of the same organism. The most common biocides used in biofilm control are pure free halogen donors such as NaOCl and NaOCl/NaOBr. These, however, must be used in high quantities to be effective. In addition, several recent studies evaluating halogen efficacy on biofilms showed an increased disinfection resistance of attached bacteria to free chlorine. Free chlorine treatment at concentrations usually effective against planktonic microorganisms has little effect on the number of attached bacteria or on their metabolic activity. The data indicate that the transport of free chlorine into the biofilm is a major rate-limiting factor, and increasing concentrations did not increase biocidal efficiency. Griebe, T., Chen, C. I., Srinavasan, R., Stewart P., "Analysis of Biofilm Disinfection By Monochloramine and Free Chlorine," Biofouling and Biocorrosion In Industrial Water Systems (edited by G. Geesey, Z. Lewandowski, and H-C. Flemming), pp. 151-161, Lewis Publishers (1994).
Excessive reactivity of pure free halogen donors was overcome by using bromochlorodimethylhydantoin (BCDMH). The published study by M. Ludyansky and P. Himpler entitled "The Effect of Halogenated Hydantoins on Biofilms," NACE, Paper 405 (1997), demonstrated higher efficacy on biofilms compared to pure free halogen donors. However, while effective, it is still not an efficient halogen source when applied to biofilm.
Others have attempted to suppress biofilm growth in aquatic systems by using an oxidizing halogen with the addition of adjuvant. U.S. Pat. No. 4,976,874 to Gannon et al., incorporated herein by reference, discloses a method and formulation for the control of biofouling using an oxidizing halogen in combination with a non-oxidizing quaternary ammonium halide. However, this method poses environmental issues.
Thus, the control of biofilm in aquatic systems has typically involved the addition of oxidizing and non-oxidizing biocides to bulk water flow. However, high levels of these expensive chemicals are needed because their effectiveness is rapidly reduced as a result of exposure to the various physical and chemical conditions in specific applications since the concentration of the biocides is considerably reduced by the time the biocides reach the biofilm.


This invention provides a composition of high frequency dielectric ceramics represented by the following formula: EQU (Pb.sub.(1-x) Ca.sub.x)[(Fe.sub.0.5 Nb.sub.0.5).sub.(1-y) Sn.sub.y ]O.sub.3. wherein 0.4.ltoreq.x.ltoreq.0.62; and 0.05.ltoreq.y.ltoreq.0.1.

1. Field of the Invention
The present invention relates to a novel composition of high frequency dielectric ceramics. More particularly, the present invention relates to compositions of high frequency dielectric ceramics having high Q values, high dielectric constants, and stable temperature coefficients of the resonant frequency.
2. Description of the Prior Art
Recently, various communication systems using microwave frequencies with a frequency range of 300 MHz to 300 GHz have been developed. These include mobile radio communication systems such as wireless telephone sets, earphones, satellite broadcasting systems, satellite communication systems and the like. Such systems require high frequency dielectric ceramics applicable to resonators, band-pass (or band-stop) filters, duplexers and microwave integrated circuits (MICs) and the like, and demand for such components have greatly increased. High frequency dielectric ceramics to be applied to such communication systems should have the following characteristics: (1) a high dielectric constant, which is required for miniaturization of parts made of dielectric ceramics because the wavelength of microwaves within dielectric ceramics is inversely proportional to the square root of the dielectric loss; (2) a high Q value corresponding to a reciprocal of the dielectric loss, which is required for high performance because dielectric losse is directly proportional to frequency; and (3) a low temperature coefficient of the resonant frequency of a dielectric resonator. See, W. Wersing, "Electronic Ceramics;, B.C.H. Steele ed., p. 67, Elsevier Sci. Pub. Co., New York (1991). In addition, high frequency dielectric ceramics to be applied to such communication systems should have a small change in properties with time, high thermal conductivity and good mechanical strength.
Examples of dielectric ceramics which have been heretofore developed include a Ba(M.sup.+2.sub.1/3,M.sup.+5.sub.2/3)O.sub.3 system wherein M.sup.+2 is Mg or Zn, and M.sup.+5 is Ta or Nb, a Ba.sub.2 Ti.sub.9 O.sub.20 system, and a (Zr,Sn)TiO.sub.4 system. These types of dielectric ceramics have low dielectric loss, while they have dielectric constant less than about 40. See, W. Wersing, supra, and J. Kato, JEE, Sep., pp. 114-118 (1991).
Other examples include a BaO--Sm.sub.2 O.sub.3 --TiO.sub.2 system, a (Ba,Pb)O--Nd.sub.2 O.sub.3 --TiO.sub.2 system, and a (Pb,Ca)ZrO.sub.3 system. These types of dielectric ceramics have dielectric constants as high as about 80, while they have relatively high dielectric losse. For Example, the (Pb,Ca)(Fe,Nb)O.sub.3 system which currently attracts attention in the art, in its optimal composition, has a dielectric constant of about 91 and T.sub.f of +2.2 ppm/.degree. C., while having low Q.sub.x F.sub.0 value of 4,950. See, J. Kato, et al.; Jpn. J. Appl. Phys., Vol. 31, pt. 1, No 9B (1992).
Generally, materials having high dielectric constants exhibit increased dielectric losses and high temperature coefficients of the resonant frequency due to the dipoles and structural defects associated therewith. Furthermore, high dielectric constant materials having high dielectric losses are not suitable for high frequency filters since they lead input signal losses to increase whereby signal transmission is difficult. Therefore, there is a need for a composition which meets the three requirements for high frequency dielectric materials: high dielectric constants, low dielectric losses and stable temperature coefficients of the resonant frequency.
On the other hand, conventional dielectric materials comprising PbO, such as a BaO--PbO--Nd.sub.2 O.sub.3 --TiO.sub.2 system, (Pb,Ca)ZrO.sub.3 system, (Pb,Ca)(Fe,Nb)O.sub.3 system, are usually sintered above about 1300.degree. C. Due to such high sintering temperatures, when the materials are synthesized or sintered, PbO is volatized and consequently, the chemical equilibrium collapses resulting in irregularity of dielectric properties of the materials produced. Therefore, it is desirable to obtain sintered materials which have consistent dielectric properties after sintering.

Korea Institute of Science and Technology