A semiconductor nanocrystal complex that is stable and has high luminescent quantum yield. The semiconductor nanocrystal complex has a semiconductor nanocrystal core of a III-V semiconductor nanocrystal material. A method of making a semiconductor nanocrystal complex is also provided. The method includes synthesizing a semiconductor nanocrystal core of a III-V semiconductor nanocrystal material, and forming a metal layer on the semiconductor nanocrystal core after synthesis of the semiconductor nanocrystal core.

Semiconductor nanocrystals are typically tiny crystals of II-VI, III-V, IV-VI materials that have a diameter between 1 nanometer (nm) and 20 nm. In the strong confinement limit, the physical diameter of the nanocrystal is smaller than the bulk excitation Bohr radius causing quantum confinement effects to predominate. In this regime, the nanocrystal is a 0-dimensional system that has both quantized density and energy of electronic states where the actual energy and energy differences between electronic states are a function of both the nanocrystal composition and physical size. Larger nanocrystals have more closely spaced energy states and smaller nanocrystals have the reverse. Because interaction of light and matter is determined by the density and energy of electronic states, many of the optical and electric properties of nanocrystals can be tuned or altered simply by changing the nanocrystal geometry (i.e. physical size).
Single nanocrystals or monodisperse populations of nanocrystals exhibit unique optical properties that are size tunable. Both the onset of absorption and the photoluminescent wavelength are a function of nanocrystal size and composition. The nanocrystals will absorb all wavelengths shorter than the absorption onset, however, photoluminescence will always occur at the absorption onset. The bandwidth of the photoluminescent spectra is due to both homogeneous and inhomogeneous broadening mechanisms. Homogeneous mechanisms include temperature dependent Doppler broadening and broadening due to the Heisenburg uncertainty principle, while inhomogeneous broadening is due to the size distribution of the nanocrystals. The narrower the size distribution of the nanocrystals, the narrower the full-width half max (FWHM) of the resultant photoluminescent spectra. In 1991, Brus wrote a paper reviewing the theoretical and experimental research conducted on colloidally grown semiconductor nanocrystals, such as cadmium selenide (CdSe) in particular. Brus L., Quantum Crystallites and Nonlinear Optics, Applied Physics A, 53 (1991)). That research, precipitated in the early 1980's by the likes of Efros, Ekimov, and Brus himself, greatly accelerated by the end of the 1980's as demonstrated by the increase in the number of papers concerning colloidally grown semiconductor nanocrystals.
Quantum yield (i.e. the percent of absorbed photons that are reemitted as photons) is influenced largely by the surface quality of the nanocrystal. Photoexcited charge carriers will emit light upon direct recombination but will give up the excitation energy as heat if photon or defect mediated recombination paths are prevalent. Because the nanocrystal may have a large surface area to volume ratio, dislocations present on the surface or adsorbed surface molecules having a significant potential difference from the nanocrystal itself will tend to trap excited state carriers and prevent radiactive recombination and thus reduce quantum yield. It has been shown that quantum yield can be increased by removing surface defects and separating adsorbed surface molecules from the nanocrystal by adding a shell of a semiconductor with a wider bulk bandgap than that of the core semiconductor.
Inorganic colloids have been studied for over a century ever since Michael Faraday's production of gold sols in 1857. Rossetti and Brus began work on semiconductor colloids in 1982 by preparing and studying the luminescent properties of colloids consisting of II-VI semiconductors, namely cadmium sulfide (CdS). (Rossetti, R.; Brus L., Electron-Hole Recombination Emission as a Probe of Surface Chemistry in Aqueous CdS Colloids, J. Phys. Chem., 86, 172 (1982)). In that paper, they describe the preparation and resultant optical properties of CdS colloids, where the mean diameter of the suspended particles is greater than 20 nm. Because the sizes of the particles were greater than the exaction Bohr radius, quantum confinement effects that result in the blue shifting of the fluorescence peak was not observed. However, fluorescence at the bulk bandedge energies were observed and had a FWHM of 50-60 nm.
CdS colloids exhibiting quantum confinement effects (blue shifted maxima in the absorption spectra) were being prepared since 1984. (Fotjik A., Henglein A., Ber. Bunsenges. Phys. Chem., 88, (1984); Fischer C., Fotjik A., Henglein A., Ber. Bunsenges. Phys. Chem., (1986)). In 1987, Spanhel and Henglein prepared CdS colloids having mean particle diameters between 4 and 6 nm. (Spanhel L., Henglein A., Photochemistry of Colloidal Semiconductors, Surface Modification and Stability of Strong Luminescing CdS Particles, Am. Chem. Soc., 109 (1987)). The colloids demonstrated quantum confinement effects including the observation of size dependent absorption maxima (first exciton peaks) as well as size dependent fluorescent spectra. The colloids were prepared by bubbling a sulphur containing gas (H2S) through an alkaline solution containing dissolved cadmium ions. The size and resultant color (of the fluorescence) of the resultant nanocrystals were dependent upon the pH of the solution. The colloids were further modified or "activated" by the addition of cadmium hydroxide to the solution that coated the suspended nanocrystals. The resultant core-shell nanocrystals demonstrated that the quantum yield of the photoluminescence was increased from under 1% to well over 50% with a FWHM of the photoluminescent spectra under 50 nm for some of the preparations.
Kortan and Brus developed a method for creating CdSe coated zinc sulphide (ZnS) nanocrystals and the opposite, zinc sulphide coated cadmium selenide nanocrystals. (Kortan R., Brus L., Nucleation and Growth of CdSe on ZnS Quantum Crystallite Seeds, and Vice Versa, in Inverse Micelle Media, J. Am. Chem. Soc., 112 (1990)). The preparation grew ZnS on CdSe "seeds" using a organometallic precursor-based reverse micelle technique and kept them in solution via an organic capping layer (thiol phenol). The CdSe core nanocrystals had diameters between 3.5 and 4 nm and demonstrated quantum confinement effects including observable exciton absorption peaks and blue shifted photoluminescence. Using another preparation, CdSe cores were coated by a 0.4 nm layer of ZnS. The photoluminescence spectra of the resultant core-shell nanocrystals indicates a peak fluorescence at 530 nm with an approximate 40-45 nm FWHM.
Murray and Bawendi developed an organometallic preparation capable of making CdSe, CdS, and CdTe nanocrystals. (Murray C., Norris D., Bawendi M., Synthesis and Characterization of Nearly Monodisperse CdE (E=S, Se, Te) Semiconductor Nanocrystallites, J. Am. Chem. Soc., 115, (1993)). This work, based on the earlier works of Brus, Henglein, Peyghambarian, allowed for the growth of nanocrystals having a diameter between 1.2 nm and 11.5 nm and with a narrow size distribution (<5%). The synthesis involved a homogeneous nucleation step followed by a growth step. The nucleation step is initiated by the injection of an organometallic cadmium precursor (dimethyl cadmium) with a selenium precursor (TOPSe-TriOctylPhosphine Selenium) into a heated bath containing coordinating ligands (TOPO-TriOctylPhosphineOxide). The precursors disassociate in the solvent, causing the cadmium and selenium to combine to form a growing nanocrystal. The TOPO coordinates with the nanocrystal to moderate and control the growth. The resultant nanocrystal solution showed an approximate 10% size distribution, however, by titrating the solution with methanol the larger nanocrystals could be selectively precipitated from the solution thereby reducing the overall size distribution. After size selective precipitation, the resultant nanocrystals in solution were monodisperse (capable of reaching a 5% size distribution) but were slightly prolate (i.e. nonspherical having an aspect ratio between 1.1 and 1.3). The photoluminescence spectra show a FWHM of approximately 30-35 nm and a quantum yield of approximately 9.6%.
Katari and Alivisatos slightly modified the Murray preparation to make CdSe nanocrystals. (Katari J., Alivisatos A., X-ray Photoelectron Spectroscopy of CdSe Nanocrystals with Applications to Studies of the Nanocrystal Surface, J. Phys. Chem., 98 (1994)). They found that by substituting the selenium precursor TOPSe with TBPSe (TriButylPhosphineSelenide), nanocrystals were produced that were monodisperse without size selective precipitation, were crystalline, and spherical. The nanocrystals were size tunable from 1.8 nm to 6.7 nm in diameter and had an exciton peak position ranging from 1.9-2.5 eV (corresponding to 635-496 nm wavelength). Like the Murray paper, TOPO was used as the coordinating ligand.
Hines and Guyot-Sionest developed a method for synthesizing a ZnS shell around a CdSe core nanocrystal. (Hines et al., "Synthesis and Characterization of strongly Luminescing ZnS capped CdSe Nanocrystals"; J. Phys. Chem., 100:468-471 (1996)). The CdSe cores, having a monodisperse distribution between 2.7 nm and 3.0 nm (i.e. 5% size distribution with average nanocrystal diameter being 2.85 nm), were produced using the Katari and Alivisatos variation of the Murray synthesis. The photoluminescence spectra of the core shows a FWHM of approximately 30 nm with a peak at approximately 540 nm. The core CdSe nanocrystals were separated, purified, and resuspended in a TOPO solvent. The solution was heated and injected with zinc and sulphur precursors (dimethyl zinc and (TMS)2S) to form a ZnS shell around the CdSe cores. The resultant shells were 0.6±0.3 nm thick, corresponding to 1 -3 monolayers. The photoluminescence of the core-shell nanocrystals had a peak at 545 nm, FWHM of 40 nm, and a quantum yield of 50%.
One exemplary problem associated with known colloidal shell synthesis methods is that they are limited in regard to the growth of high quality III-V semiconductor nanocrystals due, at least in part, to the covalent nature of the material. Past attempts at growing III-V semiconductor nanocrystals have resulted in quantum yields of approximately 10%. Micic et al., J. Phys. Chem. B. 2000, 104, 12149 -12156. It has been shown using a slow growth technique that indium phosphate (InP) core nanocrystals with a shell of zinc sulphide (ZnS) may result in quantum yields of 20% but this process takes days to complete. Haubold et al., ChemPhysChem 2001, 5, 331. Many applications of nanocrystal complexes, such as LEDs, inks, and pigments, require higher luminescent quantum yields.
Additionally, the growth of III-V nanocrystals is difficult because of the need for vacuum growth and strict humidity conditions. Etching has shown to improve the quantum yield of III-V materials however, the etching process introduces problems when bonding ligands to the surface of the nanocrystals. This causes poor colloidal stability and makes the complexes incompatible for a variety of applications. In addition, the etched surface does not provide sufficient electronic passivation. As a result, electronic interaction between a matrix material and the nanocrystal may result in fluorescence quenching.
Additionally, etching relies on photoexcitation, which requires dilute mixtures. This is not conducive to the scale up and production of large quantities of III-V semiconductor nanocrystal complexes. By readily losing their fluorescence, these quantum dot materials are simply unsuitable for most applications.
Thus, it is necessary to develop a stable III-V semiconductor nanocrystal complex that is brightly fluorescing, and soluble in most common solvents.

III-V semiconductor nanocrystal complexes and methods of making same


A RF connector assembly, suitable for millimeter waves comprises a housing, holding a transmission line and a RF connector. The transmission line has a band conductor held in an outer conductor. The band conductor is supported by a plurality of holding pins. The holding pins are fixed by holes in the outer conductor and penetrate the inner conductor through holes therein. The holding pins are injection molded parts made of plastic. They comprise of two sections which can be connected together by a plug and socket connection. One end of the transmission line has a printed circuit board contact for contacting a strip line, while the other end of the transmission line has a contact for connecting the inner conductor of the RF connector.

1. Field of the Invention
The invention relates to an RF connector assembly which may be used for millimeter waves and which can be mounted to a printed circuit board. A further aspect of the invention is a transmission line, which may be used to connect an RF connector to a printed circuit board. The transmission line is based on a band conductor.
2. Description of Relevant Art
A RF connector assembly is disclosed in U.S. Pat. No. 6,607,400 B1. A connector is mounted into a cutout of a printed circuit board. The electrical contact is established by soldering pads to a ground plane and to a signal line. Due to their design, such connectors are only suitable for frequencies up to order of magnitude of 1 GHz.
A millimeter wave connector for interconnecting a microstrip circuit and an external circuit is disclosed in U.S. Pat. No. 4,669,805. The connector is held in a housing, which also contains a microstrip substrate to be connected to the connector. During assembly, the flexible center conductor of the connector has to be bent to adapt to the microstrip circuit. Bending of the center conductor may cause asymmetries, which degrade the electrical characteristics of the connector.
U.S. Pat. No. 5,797,765 discloses a coaxial connector for mounting on a circuit substrate. The connector is soldered under a right angle to the surface of a substrate. For contacting the center conductor, a bond wire is used. Therefore, assembly of this connector requires complex special machines for bonding.

Transmission line and connector, where the transmission line includes holding pins extending through an inner conductor


Processed baby foods are disclosed which are formulated with oils and/or nucleotides. Oils are added to yield an acceptable ratio of the essential fatty acids, linoleic acid (LA) and α-linolenic acid (ALA). A blend of 3–6 nucleotides may be added to yield a level of 3–6 mg/100 Kcal, which are associated with a number of biological processes, the most common being the potential to optimize the health of the immune and gastrointestinal systems of breast-fed infants and some infants and young children fed commercial infant formula with added nucleotides.

This invention relates to processed baby foods to be consumed by human infants and young children from the age of about 6 months to 2 years (typically infants up to age 12 months) depending on the individual's particular stage of development and food needs. Baby foods, such as dry infant cereal, pureed foods and bakery items are well-known and have been commercially-formulated with additional key nutrients, e.g., iron, zinc, calcium, etc. In most cases, these foods are low in fat and must be carefully fed in the correct amounts to assure that infants consume an adequate amount of kilocalories (Kcals) to provide the energy required for healthy growth and development. When fat has been added by commercial processors to these foods, the ratio of two specific fatty acids (linoleic acid (LA) and α-linolenic acid (ALA)) has not been a consideration. Hence, infants who are transitioning from a high-fat liquid diet (breast milk or infant formula) to a lower-fat diet of processed baby foods (or homemade baby foods) may not be able to consume the full amount of energy and/or the correct ratios of these fatty acids, which are precursors for the synthesis of two critical long chain polyunsaturated fatty acids (LCPUFAs): arachidonic acid (AA) and docosahexaenoic acid (DHA). LCPUFAs are required for healthy infant growth, and support a broad range of metabolic processes necessary for development and/or functioning of the brain, retina and other nerve tissue.
Accordingly, there is a need for a fat blend designed for use in processed baby foods which addresses not only the quantity, but also the quality of fat with an acceptable LA:ALA ratio, thus increasing the likelihood that the energy and essential fatty acid requirements of rapidly growing infants are consistently met on a daily basis.
Similarly, breast milk and some infant formulas contain factors that have been identified as nucleotides useful to the optimized development of the immune and gastrointestinal systems. Nucleotides may be considered "conditionally essential" in rapidly growing infants living in adverse environments. The addition of these nucleotides may enhance health and growth.
Situations under which these components may become conditionally essential include certain disease states and periods of limited nutrient intake or rapid growth, along with the presence of various regulatory and developmental factors which interfere with the body's ability to synthesize nucleotides. Furthermore, when infants are transitioning to solid foods, exogenous sources of dietary nucleotides may be particularly important. Examples include: 1) the breast-fed infant whose intake of breast milk decreases to less than the recommended intake (600–720 mL) resulting in a concurrent decreased intake of nucleotides; and 2) the formula-fed infant whose diet is low in nucleotides. In addition, the first complementary foods are often cereal, fruits and vegetables, all of which are poor sources of nucleotides. Thus, nucleotides may be conditionally essential, with the prudent step being to provide the infant with an additional dietary source of these factors. There are no formulations for baby foods that are supplemented with nucleotides. Accordingly, there is a need for processed baby foods to be supplemented with these components for increasing the likelihood that the needs for nucleotides by rapidly growing infants, transitioning to complementary foods, are consistently met on a daily basis.


A laser apparatus for producing a laser light beam can include a gain medium; a pump light source to provide a pump light beam to the gain medium; a first reflector disposed between the first gain medium and the first pump light source and spaced apart from a gain portion of the first gain medium; a second reflector; and an output coupler. The first reflector is substantially reflective to the laser light beam and substantially transmissive to the pump light beam. The first and second reflectors and the output coupler define a folded beam path having a first portion and a second portion. The first portion of the beam path extends from the first reflector to the second reflector through the gain medium and the second portion of the beam path extends from the first reflector to the output coupler through the gain medium. The first and second beam paths define, within the gain medium, a non-zero folding angle. Optionally, the laser apparatus can include a second pump light source that can pump the same, or a second, gain medium.

High power, diode laser pumped, solid-state lasers have many potential applications, for example, ceramic or silicon wafer scribing and drilling; diamond cutting and scribing; and laser marking and engraving. Examples of such lasers include TEMoo or low-order-mode (LOM) devices with either continuous wave (CW) or Q-switched output at, for example, 1 μm or at the 2nd, 3rd or 4th harmonic wavelength.
With the rapid development of diode-pumped solid-state lasers during the past two decades, a number of approaches have been investigated with the goal of increasing the overall efficiency of such devices. Pumping schemes using high power fiber coupled diode lasers have been the most popular and efficient approaches for end pumping. Such schemes have shortcomings such as complexity, reliability (pointing and damage), limitations on power scale up, and higher cost.
To achieve high optical-to-optical efficiency, good mode matching is preferred. Mode matching increases the coupling (e.g., overlapping) between the TEMoo mode of the laser resonator and the excited volume in the gain medium within the resonator. In general, there are two basic ways to pump the laser gain medium (crystal): end pumping (longitudinally pumped) and side pumping (transversely pumped). Side pumped lasers have been developed using Nd3+ doped crystals, such as Nd:YLF and Nd:YAG. The side pumping (transversely pumped) scheme generally has better scalability to higher power levels because the pumping radiation from a diode array or a fiber coupled laser diode is directed through a lens or optical system into the laser medium normally perpendicular to the laser cavity mode. With side pumping, strong pumping absorption is preferentially near the side surface of the gain medium while the laser cavity mode is normally located in the interior of the gain medium. For this reason, mode matching can be poor compared to end pumping and can result in low efficiency (typically 15 to 30%). End pumping (longitudinally pumped) remains attractive because of the potential of good mode matching for a highly efficient diode-pumped laser system.
The laser resonator mode cross section is often circular in shape because regular symmetric resonator optics and a circular beam are preferred for many laser applications. The pumping source, for example, a high power diode laser bar, often has an asymmetric beam shape. One example of a pumping source is a 40W laser bar, such as Coherent Product No. 1024355, with a 10×0.001 mm emitting window, 10×35° full divergence angle (FWHM—full width, half maximum) and with M2˜1 in the fast axis direction while more than a thousand in the slow axis direction. In such instances, pumping beam shaping is used. Diode laser beam shaping technologies have been developed using reflective optics or refractive optics. Typically, beam shaping reduces M2 along the slow axis while sacrificing beam quality along the fast axis in order to match M2 in the two directions to form a circular beam. Special optics or special arrangements are used to perform the beam shaping. Focusing or delivery optics are used to guide the beam to pump the gain medium.
Optical fiber, due to its symmetric cross section and flexible characteristic, is widely used for diode laser beam shaping and pumping beam delivery. It has desirable characteristics for end pumping: circular beam shape and quasi-flat top intensity distribution (by multimode fiber or fiber bundle). This can lead to a preferred pumping volume with a parabolic temperature distribution profile. Fiber delivery also has its shortcomings. First, there is system complexity: at the diode laser input side, beam shaping and coupling optics are needed, while at the pumping side, a collimator and focusing optics are needed. Second, loss from the fiber coupling and delivery system is typically 25% or more. Third, reliability is a concern for laser stability because of pointing variation in the pumping beam if the fiber is moved or bent while the laser system is in operation. Fourth, optical damage at the fiber input surface, or mechanical damage due to over bending, twisting or other stress, can cause problems. Fifth, optical damage of the gain medium can produce a limit for pump power scale up at each end of the gain medium. For example, the damage threshold is approximately 19.25 W/mm2 at 1% doping level for one of the most efficient laser crystals, Nd:YVO4.

Longitudinally pumped solid state laser and methods of making and using


A refined segmentation system, method and device of an image shadow area are provided. The system of the present invention includes: a feature extraction network, a reverse fusion network, and a weighted fusion network. The feature extraction network includes a plurality of sampling layers which are arranged sequentially, a plurality of segmentation features of the shadow areas in the input images are obtained through the sampling layers sequentially. The reverse fusion network includes a plurality of layered reverse fusion branches, each of which includes a plurality of feature fusion layers arranged in sequence, and two input features are fused in sequence through each feature fusion layer. The weighted fusion network is configured to perform weighted fusion on outputs of the plurality of reverse fusion branches to obtain a final segmentation result of the shadow area of the input image.

A shadow often occurs in a natural scene and information of an image shadow area provides important information. The information can be used for estimating physical characteristics within the image, such as light sources, lighting conditions, scene geometries and the like. Understanding the image shadow area information may also assist in some other computer vision tasks, including image segmentation. Additionally, removing the shadow in an image has many applications in the field of computational imaging. Segmentation of the shadow area is an important and fundamental step in computational imaging. The present invention provides improvements to the segmentation of a shadow area within an image.
Given a single input image, segmentation of a shadow area is very challenging. Accurate segmentation of a two-dimensional image is also an "ill-conditioned" problem due to a lack of information. Scene geometries, surface characteristics, light source conditions and the like are obviously lesser developed in two, as opposed to three dimensions. Image priori and physical models based on information, such as illumination, color, and the like, are well developed in early methods. These model-based methods, however, have difficulty accurately locating a shadow area within an image if assumed conditions are difficult to satisfy. In order to meet this challenge, there are proposed methods based on learning and manual design features. However, due to the limitations of an expression capacity of manually designed features, prior learning-based methods also have difficulty dealing with difficult situations under natural conditions.
By using a deep neural network, an end-to-end learning process may be performed according to a large number of recorded samples. Hence, by learning a feature robustly expressed in an image, a segmentation method of a shadow area in the image may be rapidly developed using the deep neural network. However, the difficulty in obtaining a refined segmentation result of the shadow area remains for prior segmentation methods.
Since substantial capacities for discrimination, classification and spatial localization are required concurrently in refined segmentation of a shadow area, effectively fusing these functions to a successful end is critical. Generally, strong discrimination and classification features are encoded in deeper layers of the deep neural network. The deeper features have rich classification and discrimination information, but on a small scale with insufficient spatial detail information. In contrast, generally, strong spatial localization features are encoded in shallower layers of the deep neural network. The shallower features have rich spatial detail information. These shallower features, however, have a weak discrimination and classification capacity.

Refined segmentation system, method and device of image shadow area

INSTITUTE OF AUTOMATION, CHINESE ACADEMY OF SCIENCES


A brushless motor according to the present invention provided with a recording disk in a rotational member and serving to rotate the recording disk together with the rotational member comprises a first position detecting means for detecting a rotational position of the rotational member, a second position detecting means for detecting a rotational position of the recording disk, wherein a mode for rotating the rotational member at a high speed by a detection signal of the first position detecting means and a mode for rotating the rotational member at a low speed by a detection signal of the second position detecting means are generated. Thereby, the two rotation states whose rotation speeds are different can be obtained in a simplified constitution.

1. Field of the Invention
The present invention relates to a brushless motor used for rotating a recording disk such as CD and DVD and a disk drive device in which the brushless motor is installed.
2. Background Information
In general, a brushless motor for rotating a discoid recording disk comprises a fixing-side frame, a shaft rotatably supported by the fixing-side frame via a bearing, a rotor mounted on the shaft and rotated integrally with the shaft, a rotor magnet mounted on the rotor, and a stator supported by the fixing-side frame at a position opposing to the rotor magnet. Further, the rotor is provided with a turn table on which the disk is disposed, and the disk is rotated by rotating the rotor in the state in which the disk is disposed on the turn table.
The stator comprises a stator core having a plurality of teeth, and stator windings of, for example, three phases wound around the respective teeth of the core. The rotor magnet is formed in, for example, a cylindrical shape, and magnetized in a multipolar manner in such manner that different magnetic poles are circumferentially alternately arrayed. When a direction of a current distributed to the stator windings of the respective phases is changed, magnetic poles of the stator are rotated in one direction, which repeatedly generates attraction and repulsion relative to the magnetic poles of the rotor magnet. As a result, the rotor can obtain a rotating force.
In the foregoing constitution, as a means for detecting the magnetic poles of the rotor magnet and a rotational position of the rotor in order to change the current distribution with respect to the stator windings of the respective phases, a plurality of position detecting sensors (for example, three corresponding to the respective phases) such as Hall elements is disposed on the fixing-side frame in such manner that the respective sensors are shifted by a predetermined phase. Usually, the position detecting sensors are disposed on a circuit substrate provided on a lower side of the rotor magnet and secured to the fixing-side frame, and also disposed on a radially inner side relative to the rotor magnet and between the adjacent teeth of the stator core.
In recent years, a digital data processing speed has been increasingly advancing, in response to which the disk rotation has successfully attained a higher speed in the disk rotation motor of the foregoing type. As a recent trend, high-speed data recording and reproduction are realized by rotating the disk at such a high speed as, for example, approximately 12,000 rpm. However, it is contradictorily demanded to rotate the disk, which is installed in the high-speed disk rotation motor, at a low speed (for example, at most 100 rpm) using the motor. For example, in the case of rendering/printing data in various manners on a label surface (surface contrary to a recording surface) of the disk using a laser-type pickup device for recording and reproducing the data on the recording surface of the disk, it is necessary to rotate the disk at a low speed. However, it was almost impossible to respond to the demands that the low-speed rotation control and the high-speed rotation control are both satisfied by the rotation control of the conventional brushless motor in which only the position detecting sensors such as the Hall elements are provided.
A possible method in order to satisfy the foregoing demands which is conventionally employed is that the rotor is controlled to rotate at a high speed using the position detecting sensors such as the Hall elements, while an encoder is combined with a rotation shaft of the rotor so that a FG pulse required for controlling the low-speed rotation is generated from a rotation detection signal of the encoder and used to control the low-speed rotation. However, in the aforementioned method, the additional provision of the encoder results in complicating the structure and increasing costs. As a result, it becomes disadvantageously difficult to downsize the entire motor.

Brushless motor and disk drive device using the same


Disclosed are a semiconductor device and a method for manufacturing the same. The semiconductor device includes an isolation area formed on a semiconductor substrate to define NMOS and PMOS areas, a gate insulating layer and a gate formed on each of the NMOS and PMOS areas, a primary gate spacer formed at sides of the gate, LDD areas formed in the semiconductor substrate at sides of the gate, a secondary gate spacer formed at sides of the primary gate spacer, source and drain areas formed in the semiconductor substrate at sides of the gate of the PMOS area; and source and drain areas formed in the semiconductor substrate at sides of the gate of the NMOS area, wherein the source and drain areas of the NMOS area are deeper than the source and drain areas of the PMOS area.

FIGS. 1 to 3 are views showing a method for manufacturing a symmetric semiconductor device.
Referring to FIG. 1, after forming an isolation area 11 on a semiconductor substrate 10 through a shallow trench isolation (STI) technology, an insulating layer 12 and a polysilicon layer 13 are stacked on the resultant structure. The semiconductor substrate 10 has areas for an N-type metal oxide semiconductor (NMOS) and a P-type MOS at one side and the other side thereof with respect to the isolation area 11.
As shown in FIG. 2, the insulating layer 12 and the polysilicon layer 13 are patterned to form gate insulating layers 12a and 12b and gate electrodes 13a and 13b respectively on the NMOS and PMOS area. Then, symmetric lightly doped drain (LDD) areas 14a and 14b are formed through respective ion implantation processes.
Thereafter, as shown in FIG. 3, after forming spacers 16a and 16b at sidewalls of the gate electrodes 13a and 13b, source and drain areas 15a and 15b are formed on the NMOS and PMOS areas through respective ion implantation processes.
However, problems in the structure of the symmetric semiconductor device are as follows.
First, a symmetric LDD structure having the same size at sides of each gate degrades a sub-threshold characteristic, reducing a driving current in a saturation state.
Second, in an inversion mode in which a sub-threshold current occurs, the LDD area at a source area degrades a swing characteristic of the device, and parasitic capacitance in an overlap area between the gate and the LDD area becomes a factor, reducing the operating speed of the device.
For example, when a flip-flop circuit is formed using the symmetric semiconductor device, an edge part of a swing characteristic graph cannot be not perpendicularly formed due to the influence of the driving current and the capacitance, so the swing characteristic graph has a parabolic configuration, representing propagation delay time.
Since the propagation delay time is proportional to the capacitance and inversely-proportional to an amount of driving current in each MOS area, the symmetric semiconductor device has a limitation in reducing the propagation delay time.
Third, a junction depth of an active area is important to control a critical dimension and an effective channel length of the gate electrode. Accordingly, the junction depth can be adjusted through an ion implantation process of indium (In) and/or antimony (Sb), which is are heavy ions, and a laser spike anneal process. In addition, the driving current may be reduced by forming a junction through a SiGe self aligned epitaxial growth scheme.
However, even if the junction depth is adjusted through the above method, short channel effects (SCEs) such as gate induced drain leakage (GIDL) and drain induced barrier lowering (DIBL), reverse short channel effects, and a problem of the parasitic capacitance still remain.
In addition, although the semiconductor device may be highly integrated, a driving voltage is relatively high, so electrons supplied from a source are excessively accelerated due to the potential gradient of the drain, a hot carrier instability phenomenon occurs in the vicinity of the drain, and the adjustment of a threshold voltage is very difficult.

Semiconductor device and method for manufacturing the same


Fuel supply system (1) for internal combustion engines, arranged in a suction channel (2) leading to the engine body proper, the system (1) comprising one or several air-regulating valves (5,6) and one or several nozzles (3,3'). A cavity (7) or channel is provided in the wall of the suction channel (2) and is positioned in such a manner that when the air-regulating valve (5,6) assumes its closed position the cavity or the channel creates a communication path (21) from one side of the air-regulating valve to the other one, and in that an at least partly movable body (8) is positioned adjacent the cavity (7) or channels in such a manner as to be able to affect the through-flow resistance in the communication path (21). The position of the movable body (8) is controlled by a temperature-responsive member (9), for instance a bimetal element.

Carburettors for two-stroke or four-stroke engines are arranged in a suction channel leading to the engine body proper. Often, the carburettor has two air-regulating valves, viz. one throttle valve or air throttle and one choke valve. The throttle valve is used to control the throttle whereas the choke valve is used for cold starts. Usually, the choke valve closes entirely manually or automatically. A small opening in the choke valve ensures that only a minute amount of air flows past the valve upon starting attempts. As a result a very powerful negative pressure generates inside the suction channel adjacent the downstream nozzles. Consequently, a lot of fuel is supplied, giving a very rich air fuel mixture. This is necessary, since large quantities of fuel condensate on the walls of the suction channel, the crank case and the combustion chamber under these conditions. Carburettors do also exist that are equipped with one single air-regulating valve which in this case acts both as a throttle valve and a choke valve. Further, there are injection systems having a separate starting system including choke valves and starter nozzles that work in accordance with the carburettor principle. During start-ups the fuel amount is heavily influenced by the negative pressure from the choke valve.
It is characterstic of these kind of fuel supply system that during cold starts an air-regulating valve, usually designated choke valve, is almost fully closed whereby a heavy negative pressure is formed downstream of the air-regulating valve. Very often the valve is fully closed and a small opening ensures the required by-pass of a small amount of air. Obviously, it is also possible to use an end-position stop means for the air-regulating, valve whereby the latter will gape slightly open and no air opening is required. The size of the minute air opening is dimensioned to suit the lowest starting temperature at which the product usually is used. In the case of chainsaws this temperature could be e.g. -25.degree. C. This means that at higher temperature levels, for instance +20.degree. C., the air opening is too small to provide an accurate fuel-air mixture at start-ups. This gives an unnecessarily rich fuel mixture and complicates or prevents the starting function. In addition, the rich fuel mixture leads to unnecessary engine sooting and unnecessarily large exhaust emissions. For when the product is started the choke is turned to full open, since in reality it is hardly possible to "finely tune" the controls ensuring that the air opening coincides with the demand.


A drying unit in a dryer section of a paper or board machine including a drying wire guided in a loop, a large-diameter impingement-drying and/or through-drying cylinder arranged inside the drying-wire loop and smaller diameter smooth-faced heated contact-drying cylinders arranged on top of the large cylinder and/or in the vicinity thereof and at both sides thereof. The impingement-drying and/or through-drying cylinder is placed in a space below the floor level of the paper machine hall and provided with an openable and closable blow hood so that the removal of broke out of connection with the hood takes place substantially by the force of gravity. The central axes of the contact-drying cylinders placed in the vicinity of the large cylinder are placed in the vicinity of, or above, the floor level of the paper machine hall. A curve sector of the paper web on the outer face of the drying wire over the large cylinder greater than about 180.degree..

Even though, above and in the following, paper and paper machines are spoken of, in the present invention, these terms also include board and board machines.
The highest web speeds in paper machines are today up to an order of about 25 meters per second (mps) and slightly higher, but before long, a web running speed in the range of 25-40 meters per second will be commonly used. In such a case, a bottleneck for the runnability of a paper machine will be the dryer section, whose length with the prior art multi-cylinder dryers would also become intolerably long. If it is imagined that a present day multi-cylinder dryer were used in a newsprint machine at a web speed of about 40 mps, it would include about 70 drying cylinders (.phi..apprxeq.1800 mm), and its length in the machine direction would be about 180 meters. In such a case, the dryer section would comprise about 15 separate wire groups and a corresponding number of draws over group gaps. It is probable that, in a speed range of 30-40 mps, the runnability of normal prior-art multi-cylinder dryers is no longer even nearly satisfactory, but web breaks would occur quite often lowering the efficiency of the paper machine.
In a speed range of 30-40 mps and at higher speeds, the prior art multi-cylinder dryers would also become uneconomical because the cost of investment of an excessively long paper machine hall would become unreasonably high. It can be estimated that the cost of a paper machine hall is at present typically about 1 million FIM per meter in the machine direction.
In the prior art, in multi-cylinder dryers of paper machines, twin-wire draw and/or single-wire draw is/are employed. When employing twin-wire draw, a group of drying cylinders comprises two closed (endless) wires, fabrics or belts which press the web one from above and the other one from below against heated cylinder faces of drying cylinders arranged in rows. Between the rows of drying cylinders, which are usually horizontal rows, the web has free and unsupported draws which are susceptible to fluttering and may cause web breaks, in particular when the web is still relatively moist and, therefore has a low strength. For this reason, in recent years, ever increasing use has been made of the single-wire draw in which each group of drying cylinders includes only a single closed (endless) drying wire on whose support the web runs through the entire group so that the drying wire presses the web on the drying cylinders against the heated cylinder faces thereof, whereas on the reversing cylinders or rolls between the drying cylinders, the web remains at the side of the outside curve and is subjected to negative pressure as it runs over the reversing cylinders in order to maintain the web on the wire. Thus, in single-wire draw, the drying cylinders are arranged outside the wire loop, and the reversing cylinders or rolls are arranged inside the wire loop.
It is known to those skilled in the art that if paper is dried one-sidedly, the result is a tendency of curling of the sheet. For example, when paper is dried by means of normal groups with single-wire draw from the side of its bottom face only, the drying is asymmetric and if such asymmetric drying is extended over the entire length of the forward dryer section, the drying takes place so that first the bottom-face side of the paper web is dried and, when the drying makes progress, the drying effect is also extended to the side of the top face of the paper web. Under these circumstances, the dried paper is usually curled and becomes concave, when viewed from above.
One parameter that illustrates the drying capacities of the prior art multi-cylinder dryers is the amount of water evaporated in the dryer section per unit of length and width, i.e., per floor area covered by the web to be dried, within a unit of time. In prior art multi-cylinder dryers, this parameter is typically in the range of 50-80 kilograms of H.sub.2 O per square meter per hour.
It is known from the prior art to use various impingement-drying/through-drying units for evaporation drying of a paper web, which units have been employed in particular in the drying of tissue paper. With respect to this prior art, reference is made, by way of example, to the following patent literature: U.S. Pat. Nos. 3,301,746, 3,418,723, 3,447,247, 3,541,697, 3,956,832 and 4,033,048, Canadian Patent No. 2,061,976, West German Patent Application Nos. DE-A-22 12 209 (corresponding to U.S. Pat. No. 3,816,941) and DE-A-23 64 346 (corresponding to U.S. Pat. No. 4,033,049, European Patent Application No. EP-A2-0 427 218), Finnish Patent Nos. 57,457 (corresponding to Swedish Patent Application No. 7503134-4) and 87,669 (corresponding to U.S. Pat. No. 5,383,288), and Finnish Patent Application No. 931263 (corresponding to U.S. Pat. No. 5,495,678 and European Patent Application No. 0 620 313-A1).

Drying unit and dryer section that makes use of such units


A dielectric barrier discharge type low pressure discharge lamp 11 includes dielectric barrier discharge type external electrodes 21, 22 on external ends of a tubular glass lamp vessel 10, electrically conductive material layers 31, 32 on the external surface of the tubular glass lamp vessel, and heat equalizing members 41, 42, which are provided on the electrically conductive material layer. With the constitution, the surface temperature of the external electrodes 21, 22 can be equalized with a local temperature rise avoided, thereby a longer life of the lamp can be assured.

A dielectric barrier discharge type low pressure discharge lamp (EEFL) is known, which is provided with electrodes on an external surface of a tubular glass lamp vessel, as described in the Japanese official gazette of the utility model laid open No. 61-126559, for example. The configuration of the conventional low pressure discharge lamp is shown in FIG. 3.
In FIG. 3, a low pressure discharge lamp 15 has a tubular glass lamp vessel 10, both ends of which are sealed. An ionizable discharge medium 50 such as rare gas or a mixed gas of mercury and rare gas, is enclosed inside the tubular glass lamp vessel 10. A phosphor layer 60 etc. is formed on the inner surface of the tubular glass lamp vessel, if necessary. External electrodes 25, 26 are provided on the outer surface of both ends of the tubular glass lamp vessel. The external electrodes 25, 26 are made of electrical conductive material layers 35, 36 such as, for example, a metal foil attached on the glass surface through an adhesive layer, such as in an aluminum tape electrode. Electricity feeding members 75, 76 are attached on the external electrodes 25, 26, while lead wires 81,82 are attached on the electricity feeding members 75, 76.
A low pressure discharge lamp 15 with such construction has an advantage that the consumption of electrodes is avoided and the life is long, because the electrodes are not provided inside the glass lamp vessel 10.
However, when the electrical conductive material layer 35, 36 are formed by a metal foil such as an aluminum tape electrode, a high lamp voltage must be applied to the conductive material layer 35, 36 due to an insufficient contact with the tubular glass lamp vessel 10 and to a high electric resistance of the conductive material layer 35, 36 themselves. To solve the problem it is proposed to form the external electrodes with a solder layer using an ultrasonic solder dipping method. A lamp voltage becomes lower in such an external electrode type lamp having a metal layer such as a solder electrode directly formed on a glass surface than an external electrode type lamp having a metal foil attached on an external surface of the glass lamp vessel through an adhesive layer, such as an aluminum tape electrode since the electric resistance of the electrodes themselves can be small due to their sufficiently thin thickness. Therefore, there is also an advantage that circuit design of an inverter for generating high voltage high frequency electric power becomes easier.
However, a solder electrode has a low heat capacity because the thickness is about one twentieth as thin as that of the aluminum tape electrode. For this reason, the solder electrode tends to exhibit partially uneven electrode temperature distribution compared with aluminum tape electrode. For example, in the conventional example shown in FIG. 3, where the electricity feeding members 75, 76 are provided only in the vicinity of a central portion, the temperature in the central portion of the electrode tends to decrease by heat dissipation, while the temperature on the both ends of the electrode, where electricity feeding members are not arranged, tends to become high. Therefore, there was a problem that the electrode temperature became locally high at the vicinity of the ends of the electrodes, and thus the glass material is molten to form a hole, which enables the lamp to be lit.
One of the objects of the present invention is to solve such problems, and to provide a low pressure discharge lamp in which adverse effects due to the local temperature rise in the external electrode surfaces formed by a solder layer are reduced.

Low pressure discharge lamp having external electrodes provided with heat equalizing members


The invention relates to a color temperature variable light emitter and a method, adapted for generating color temperature variable light. The color temperature variable light emitter comprises a first phosphor (1) and a second phosphor (2), the first phosphor (1) and the second phosphor (2), when pumped with pump light, being adapted for emitting first phosphor light and second phosphor light, respectively, the first phosphor light having a different wavelength from the second phosphor light, and an exit surface (11) adapted for emitting the color temperature variable light, wherein the first phosphor (1) and the second phosphor (2) are stacked in a stacking direction in such a way that at least part of the first phosphor light and at least part of the second phosphor light are combined in the exit surface (11) and emitted as the color temperature variable light, and the first phosphor (1) and the second phosphor (2) can be individually pumped by first pump light and second pump light, respectively, the first pump light and the second pump light being incident laterally relative to the stacking direction. In this way, a uniform mixing of light is achieved while preserving a high intensity of the color temperature variable light emitter.

Document WO 2008/146290 A2 describes a light source device comprising at least one light emitting element, an optical funnel for distributing light emitted by the light emitting element into a waveguide material which is in optical communication with the optical funnel and at least one reflector contacting the waveguide material for redirecting light back into the waveguide material such as to reduce illumination exiting the waveguide material in any direction other than a circumferential direction.
Different colors can be produced with a color variable lamp where phosphor is stacked on top of at least two chips emitting at two different wavelengths. The phosphor is chosen in such a way that it absorbs light differently at different wavelengths. However, two or more chips placed next to each other are required in order to increase the emission area. Furthermore, different colors are produced next to each other rather than on top of each other and due to the overlap in the absorption spectra of phosphors it is difficult to produce saturated colors.

Color temperature variable light emitter


A semiconductor memory device includes a plurality of memory cells configured to store data having a polarity corresponding to a direction of current flowing through a source line and a bit line; and a precharge driving unit configured to precharge the bit line to a voltage corresponding to the data in response to a precharging signal before the data are stored in the memory cells.

The present invention relates to a semiconductor design technology, and more particularly, to a semiconductor memory device capable of storing data by using a magnetic tunnel junction device (MTJ).
A dynamic random access memory (DRAM) and a static random access memory (SRAM) are volatile memory devices that lose data stored in a memory cell when power is interrupted. In recent years, studies on nonvolatile memory devices were carried out. One of nonvolatile memory devices is a magnetic random access memory (MRAM). In particular, an MRAM is considered as a next-generation semiconductor memory device because of its nonvolatile characteristic, high integration density, high speed operation, and low power consumption.
A memory cell of an MRAM, which is a type of a magnetic memory device, includes a transistor performing a switching operation according to an address inputted from the outside, and an MTJ storing data. The MTJ has a magnetoresistance (MR) ratio changing according to magnetization directions of two ferromagnetic materials. An internal circuit of the MRAM detects the change in an amount of current according to the MR ratio and determines whether data stored in the MTJ is "1" or "0".
FIG. 1 illustrates a memory cell architecture of a conventional semiconductor memory device.
Referring to FIG. 1, each of memory cells includes a transistor and an MTJ. For illustration purposes, a memory cell including an NMOS transistor 110 and an MTJ 130 will be described as a representative example.
The NMOS transistor 110 forms a source-drain path between a zeroth source line SL0 and an MTJ 130 and has a gate connected to a zeroth word line WL0. The NMOS transistor 110 is turned on/off in response to the activation of the zeroth word line WL0 which is selected by a row address.
The MTJ 130 includes a free layer 132, a tunnel insulation layer 134, and a pinned layer 136. The free layer 132 is formed of a ferromagnetic material and its magnetization direction is changed by external stimulus, for example, such as a current passing through the MTJ 130. A magnetization direction of the pinned layer 136 is not changed even though external stimulus is applied thereto. The magnetization direction of the pinned layer 136 is fixed by a pinning layer (not shown) formed of an antiferromagnetic material. The tunnel insulation layer 134 may be formed of magnesium oxide (MgO).
A tunneling current flows through the MTJ 130 according to a voltage applied across the MTJ 130, and the magnetization direction of the free layer 132 is determined by a direction of the tunneling current. A resistance of the MTJ 130 becomes small if the magnetization direction of the free layer 132 is identical to the magnetization direction of the pinned layer 136. It becomes large if the magnetization direction of the free layer 132 is not identical to the magnetization direction of the pinned layer 136. In general, the state where the magnetization directions of the free layer 132 and the pinned layer 136 are identical to each other corresponds to data "0", and the state when the magnetization directions of the free layer 132 and the pinned layer 136 are not identical to each other corresponds to data "1".
In other words, the magnetization directions of the free layer 132 and the pinned layer 136 become identical to each other when a positive current larger than a critical current flows by applying a positive voltage higher than a certain level to the free layer 132 with respect to the pinned layer 136. That is, an operation of writing data "0" is performed and the resistance of the MTJ 130 decreases. On the contrary, the magnetization directions of the free layer 132 and the pinned layer 136 become opposite to each other when a negative current larger than a critical current flows by applying a negative voltage higher than a certain level to the free layer 132 with respect to the pinned layer 136. That is, an operation of writing data "1" is performed and the resistance of the MTJ 130 increases.
FIG. 2 is a graph showing a current-voltage characteristic of the MTJ 130 of FIG. 1.
Referring to FIG. 2, paths 1, 8, 9 and 10 represent a case where the free layer 132 and the pinned layer 136 have an opposite magnetization direction to each other, and paths 3, 4, 5 and 6 represent a case where the free layer 132 and the pinned layer 136 have an identical magnetization direction to each other. A path 2 represents a case where a positive current larger than a critical current flows through the MTJ 130 of FIG. 2 and thus magnetization directions of the free layer 132 and the pinned layer 136 change from an opposite direction to an identical direction. A path 7 represents a case where a negative current larger than a critical current flows through the MTJ 130 and thus magnetization directions of the free layer 132 and the pinned layer 136 change from an identical direction to opposite directions.
As can be seen from FIG. 2, the MTJ 130 can have a high resistance and a low resistance due to its hysteresis characteristic, and such a stable state is kept even though power is interrupted.
FIG. 3 is a circuit diagram explaining a write operation of a conventional MRAM.
Referring to FIG. 3, the MRAM includes a plurality of memory cells MC, a source line driving unit 330, a bit line driving unit 350, a precharge driving unit 370. A reference numeral 390 represents parasitic capacitances of zeroth to third bit lines BL0, BL1, BL2 and BL3.
For illustration purposes, the following description will be focused on, a memory cell 310 on which a write operation is performed.
The memory cell 310 is connected between the first bit line BL1 and the first source line SL1 and is enabled in response to the activation of the first word line WL1. Due to the source line driving unit 330 and the bit line driving unit 350, a current larger than a critical current flows through the enabled memory cell 310, and data having a polarity corresponding to the direction of the current is stored in the enabled memory cell 310.
The source line driving unit 330 drives zeroth to second source lines SL0, SL1 and SL2 in response to a first driving control signal CTR1. The first driving control signal CTR1 has a logic level corresponding to the data. The zeroth to second source lines SL0, SL1 and SL2 are commonly connected for reducing an area of the memory cell MC.
The bit line driving unit 350 drives the first bit line BL1 in response to a second driving control signal CTR2. The second driving control signal CTR2 has a logic level corresponding to the data. The bit line driving unit 350 is provided for each of the zeroth to third bit lines BL0, BL1, BL2 and BL3. Only one bit line driving unit 350 corresponding to the first bit line BL1 is illustrated in FIG. 2. A first NMOS transistor TR1 is connected between the bit line driving unit 350 and the first bit line BL1, and is turned on/off in response to a bit line selection signal BS. The bit line selection signal BS is selected by a column address.
The precharge driving unit 370 precharges the zeroth to third bit lines BL0, BL1, BL2 and BL3 to a ground voltage VSS in response to a precharging signal PRE. The precharge driving unit 370 may be implemented with a plurality of NMOS transistors. Specifically, the NMOS transistors are connected between the zeroth to third bit lines BL0, BL1, BL2 and BL3 and a ground voltage terminal to form a source-drain path and have gates receiving the precharging signal PRE.
A write operation of the memory cell 310 will be described below. A precharging operation is performed prior to a write operation. At this point, the precharging signal PRE becomes a logic high level, and the plurality of transistors including a second NMOS transistor TR2 of the precharge driving unit 370 are turned on. Thus, the zeroth to third bit lines BL0, BL1, BL2 and BL3 are precharged to the ground voltage VSS.
The source line driving unit 330 and the bit line driving unit 350 drive the corresponding lines in response to the first driving control signal CTR1 and the second driving control signal CTR2 corresponding to the data after the precharging operation, that is, the precharging signal PRE becomes a logic low level. The zeroth to second source lines SL0, SL1 and SL2 are driven to the corresponding voltage by the source line driving unit 330, and the first bit line BL1 is driven to the corresponding voltage by the bit line driving unit 350 selected by the bit line selection signal BS. When the first word line WL1 is activated, the NMOS transistors of the memory cells including a third NMOS transistor TR3 are turned on. Hence, a current flows through the memory cell 310 according to a voltage difference between the first source line SL1 and the first bit line BL1, and the MTJ of the memory cell 310 stores "1" or "0".
To explain limitations of the conventional semiconductor memory device, an operation of writing data "1" in the memory cell 310 will be described below. Upon the operation of writing data "1", the first driving control signal CTR1 becomes a logic low level and the second driving control signal CTR2 becomes a logic high level.
As mentioned above, the zeroth to third bit lines BL0, BL1, BL2 and BL3 are precharged to the ground voltage VSS by the precharging operation. The first NMOS transistor TR1 is turned on in response to the bit line selection signal BS, and the PMOS transistor of the source line driving unit 330 is turned on. The NMOS transistor of the bit line driving unit 350 is turned on. Therefore, the zeroth to second source lines SL0, SL1 and SL2 are driven to a core voltage VCORE, and the first bit line BL1 is driven to the ground voltage VSS. When the first word line WL1 is driven, the NMOS transistors of the memory cells including the third NMOS transistor TR3 are turned on. That is, a current flows in the following order: a core voltage (VCORE) terminal of the source line driving unit 330, the first source line SL1, the memory cell 310, the first bit line BL1, and the ground voltage (VSS) terminal of the bit line driving unit 350. Through such a current flow, data "1" is stored in the MTJ of the memory cell 310.
In this case, the existing data is maintained because the NMOS transistors of the memory cells corresponding to the unselected zeroth and second word lines WL0 and WL2 are not turned on. However, problems occur in memory cells, other than the target memory cell 310, which are selected by the first word line WL1.
In the precharging operation, the zeroth to third bit lines BL0, BL1, BL2 and BL3 are precharged to the ground voltage VSS. When the first word line WL1 is activated, the NMOS transistors of the corresponding memory cells are turned on. At this point, the core voltage VCORE for writing data "1" is applied through the first source line SL1 to the memory cell 310, and an unwanted current IDIST flows through the memory cells unselected by the bit line selection signal BS, due to a voltage difference between the first source line SL1 driven to the core voltage VCORE and the zeroth, second and third bit lines BL0, BL2 and BL3 precharged to the ground voltage VSS. An amount of the current IDIST gradually decreases while charging a parasitic capacitance 390 of the zeroth, second and third bit lines BL0, BL2 and BL3, but a current flow is still maintained for a relatively short time of several nanoseconds. Such an unwanted current flow IDIST may damage data stored in the corresponding memory cell or may degrade the quality of stored data.

Semiconductor memory device and method for operating the same


A method is provided for treatment of symptoms of Ehlers-Danlos Syndromes comprising administration of a composition comprising rubeola virus, histamine and collagen.

The present invention is directed to methods and compositions for treatment of Ehlers-Danlos Syndrome (EDS). EDS is a disease complex that includes more than a dozen genetic disorders that cause defective processing of collagen, and as a result, weakened connective tissues in the body. As a broad generalization, these disorders reduce the strength and increase the elasticity of connective tissues in the body's frame (particularly those holding joints together) and may create life threatening flaws or weaknesses in the structure and performance of organs such as kidneys, intestines and blood vessels. Symptoms may include loose joints, stretchy skin, and abnormal scar formation. These can be noticed at birth or in early childhood. Complications may include aortic dissection, joint dislocations, scoliosis, chronic pain, or early osteoarthritis.
EDS is due to a mutation in one of more than a dozen different genes and affects about 1 in 5,000 people globally. The prognosis depends on the specific type. While some types result in a normal life expectancy, those that affect blood vessels generally result in a shorter life expectancy. There is no known cure for EDS and treatment is supportive in nature. For example, physical therapy and bracing may help strengthen muscles and support joints.
The specific gene affected determines the type of EDS. Some cases result from a new mutation occurring during early development while others are inherited in an autosomal dominant or recessive manner. There are currently thirteen (13) different classifications of EDS. The two most common types are hypermobile EDS (hEDS) and classical EDS (cEDS). The remaining types are very rare.
EDS is estimated to affect 1 in 5,000 people. Hypermobile EDS currently known as hEDS, which includes but is not limited to what was previously designated Type 3 EDS, is the most common of the various syndromes, affecting from a third to half of the entire EDS population (1 in 10,000 to 15,000). Type 1 and 2—Classical EDS affects approximately 1 in 20,000 to 50,000 people. It is caused by autosomal dominant mechanism and affects type-V collagen, as well as type-I collagen. Type 1 Classical EDS typically presents with severe skin involvement while type 2 presents with mild to moderate skin involvement. Patients with the Classical Type EDS may experience the same symptoms as the Hypermobility Type (hEDS). The main difference between the hEDS and Classical Types is the Classical has more skin involvement while hEDS has more joint involvement, though patients with Classical EDS can also have severe joint issues and may respond well to MCC. Other variants such as vascular EDS (vEDS), which can lead to aortic dissection, represent even smaller patient populations. vEDS is the only variant with current treatments in development (celiprolol and irbesartin). The classical form of EDS was the subject of an earlier clinical study evaluating the efficacy of IGF-I, which improved tendon collagen synthesis rates. There remains a need for a drug for the treatment of hEDS.
Identification of the subtype of EDS helps identify the nature of pathologies and their causes. A diagnosis is important because, although EDS is not curable, many symptoms are treatable. Treatment is supportive in nature. In most cases pain is a principal patient complaint, typically accompanied by high fatigue due to muscles working overtime to keep the body together. Drugs are prescribed to treat the pain but do nothing for the underlying cause of disease. Non-pharmacologic treatment of EDS patients is limited to physical therapy to help muscles to work better with ligaments to support joints and keep them safe. Hydrotherapy is particularly helpful for aerobic exercise. Finally, bracing and casting can be helpful to support joints. Unfortunately, progressive disease often leads to a wheelchair and permanent incapacitation.
Hypermobile EDS (hEDS) which includes but is not limited to what was previously designated Type 3 EDS, is characterized primarily by joint hypermobility affecting both large and small joints, which may lead to recurrent joint dislocations and subluxations (partial dislocation). In general, people with this type have soft, smooth and velvety skin with easy bruising and chronic pain of the muscles and/or bones.
Classical EDS (cEDS) is associated with extremely elastic (stretchy), smooth skin that is fragile and bruises easily; wide, atrophic scars (flat or depressed scars); and joint hypermobility. Molluscoid pseudotumors (calcified hematomas over pressure points such as the elbow) and spheroids (fat-containing cysts on forearms and shins) are also frequently seen. Hypotonia and delayed motor development may occur.
Vascular EDS (vEDS) is characterized by thin, translucent skin that is extremely fragile and bruises easily. Arteries and certain organs such as the intestines and uterus are also fragile and prone to rupture. People with this type typically have short stature; thin scalp hair; and characteristic facial features including large eyes, a thin nose, and lobeless ears. Joint hypermobility is present, but generally confined to the small joints (fingers, toes). Other common features include club foot; tendon and/or muscle rupture; acrogeria (premature aging of the skin of the hands and feet); early onset varicose veins; pneumothorax (collapse of a lung); recession of the gums; and a decreased amount of fat under the skin.
Kyphoscoliosis EDS (kEDS) is associated with severe hypotonia at birth, delayed motor development, progressive scoliosis (present from birth), and scleral fragility. Affected people may also have easy bruising; fragile arteries that are prone to rupture; unusually small corneas; and osteopenia (low bone density). Other common features include a "marfanoid habitus" which is characterized by long, slender fingers (arachnodactyly); unusually long limbs; and a sunken chest (pectus excavatum) or protruding chest (pectus carinatum).
Arthrochalasia EDS (aEDS) is characterized by severe joint hypermobility and congenital hip dislocation. Other common features include fragile, elastic skin with easy bruising; hypotonia; kyphoscoliosis (kyphosis and scoliosis); and mild osteopenia.
Dermatosparaxis EDS (dEDS) is associated with extremely fragile skin leading to severe bruising and scarring; saggy, redundant skin, especially on the face; and hernias. Brittle Cornea Syndrome (BCS) characterized by thin cornea, early onset progressive keratoglobus; and blue sclerae.
Classical-like EDS (clEDS) is characterized by skin hyperextensibility with velvety skin texture and absence of atrophic scarring, generalized joint hypermobility (GJH) with or without recurrent dislocations (most often shoulder and ankle), and easily bruised skin or spontaneous ecchymoses (discolorations of the skin resulting from bleeding underneath).
Spondylodysplastic EDS (spEDS) is characterized by short stature (progressive in childhood), muscle hypotonia (ranging from severe congenital, to mild later-onset), and bowing of limbs.
Musculocontractural EDS (mcEDS) is characterized by congenital multiple contractures, characteristically adduction-flexion contractures and/or talipes equinovarus (clubfoot), characteristic craniofacial features, which are evident at birth or in early infancy, and skin features such as skin hyperextensibility, easy bruisability, skin fragility with atrophic scars, increased palmar wrinkling.
Myopathic EDS (mEDS) is characterized by congenital muscle hypotonia, and/or muscle atrophy, that improves with age, Proximal joint contractures (joints of the knee, hip and elbow); and hypermobility of distal joints (joints of the ankles, wrists, feet and hands).
Periodontal EDS (pEDS) is characterized by severe and intractable periodontitis of early onset (childhood or adolescence), lack of attached gingiva, pretibial plaques; and family history of a first-degree relative who meets clinical criteria.
Cardiac-valvular EDS (cvEDS) is characterized by severe progressive cardiac-valvular problems (aortic valve, mitral valve), skin problems (hyperextensibility, atrophic scars, thin skin, easy bruising) and joint hypermobility (generalized or restricted to small joints).
Hypermobile EDS (hEDS) (also known as Type III EDS) is the most common form of EDS but no genetic basis for its genesis has been identified. In general hEDS is considered less severe than the other types of EDS but significant complications, particularly those of the musculoskeletal system, do occur. The skin is often soft and can be mildly hyperextendible. Subluxations and dislocations which can be acutely painful are said to be common and can occur spontaneously or with minimal trauma. Degenerative joint disease, easy bruising and chronic pain are common with the syndrome.
Hypermobile, or loose, joints that are not held tightly together by normally functioning collagen undergo frequent subluxations, dislocations and pain. This can be a significant problem when hyperextensible joints move beyond their normal range. Early onset osteoarthritis is a common consequence of this joint hypermobility as well. Many patients with hypermobile joints also report fatigue, likely caused by muscles working overtime to keep the body together. EDS also presents with skin disorders such as hyperextensibility and tissue fragility. These characteristics, which can be noticed in early childhood, help define and differentiate between the multiple subtypes of EDS that are used for classification purposes.
Taken together all the fragmented data on pain manifestations and its possible underlying mechanisms in EDS indicate a complex pathogenesis. The slow progression from episodic, low-moderate, and treatment-responsive pain at single joints to chronic, severe and disabling pain affecting the entire body is indicative of multiple contributing pathologies. Some patients are able to localize pain and experience a satisfactory life, while others feel defeated and live a very restricted existence. For these reasons there remain a need in the art for more effective treatments of EDS and the symptoms of EDS.
Histamine [4-(2-aminoethyl)-imidazole or .beta.-imidazolyl-ethylamine] is a chemical substance possessing pronounced biological activities. It is a powerful stimulant of gastric secretion and constrictor of smooth muscle. It is a vasodilator and large doses cause a relatively rapid fall in blood pressure. It is frequently noted to be liberated by epithelial cells upon traumatic injury or stimulation by antigenic substances. Its storage in and release from mast cells and basophil granules and its role in Type I hypersensitivity reactions have been the subject of extensive study.
Of interest to the present application are the disclosures of U.S. Pat. No. 5,877,198 which is directed to the administration of histamine for the treatment of the symptoms of urinary incontinence and U.S. Pat. No. 6,156,780 which is directed to the administration of histamine for the treatment of the symptoms of fecal incontinence. Also of interest is the disclosure of published application US 2014/0121256 which is directed to the administration of histamine for the treatment of muscle weakness.
Of further interest to the present application is the disclosures of U.S. Pat. No. 4,521,405 which is directed to the administration of histamine and inactivated attenuated measles virus (rubeola) for the treatment of symptoms of Multiple Sclerosis and of U.S. Pat. No. 4,705,685 which is directed to the administration of histamine and inactivated attenuated measles virus (rubeola) for the treatment of chronic pain.
Also of interest to the present invention is the disclosure of U.S. Pat. No. 4,704,273 which is directed to a administering to a subject suffering from rheumatoid arthritis an effective amount of a composition comprising a mixture of histamine, immunoglobulin G provocative of rheumatoid factor formation or an immunologically active fraction thereof, collagen and attenuated measles virus (rubeola) for alleviating the symptoms of rheumatoid arthritis such as decreasing pain, increasing mobility and flexibility, decreasing swelling, decreasing inflammation and increasing energy. Other compositions comprising attenuated measles virus (rubeola) and histamine were reported to be useful in alleviating symptoms of rheumatoid arthritis while compositions comprising histamine alone or histamine in combination with immunoglobulin G provocative of rheumatoid factor formation were reported to not be useful in alleviating such symptoms.
The patent further discloses administration of compositions comprising histamine, measles virus (rubeola) vaccine and influenza virus vaccine; of histamine and measles virus vaccine; and of histamine and influenza virus vaccine. The patent reported that subjects receiving the combination of histamine and measles virus vaccine with and without influenza virus vaccine had improvement of symptoms which those treated with the combination of histamine and influenza virus vaccine did not. Subjects treated with collagen and immunoglobulin G provocative of rheumatoid factor formation without rubeola virus or histamine did not report improvement in symptoms.

Compositions and methods of treatment of Ehlers-Danlos syndromes


A magnetic tape driving apparatus includes: a stationary magnetic head capable of recording and reproducing digital signals simultanouesly on multichannel tracks; tape guide members for drawing out a magnetic tape wound on a pair of tape supply/take-up reels contained in a cassette, contacting the magnetic tape with the stationary magnetic head, and guiding running of the magnetic tape; and a constant speed driving mechanism for holding the magnetic tape and making it run at a constant speed by capstans and pinch rollers provided on both of tape feed/take-up sides of the stationary magnetic head. The stationary magnetic head and the tape guide members having level regulators for regulating running positions of upper and lower edges of the magnetic tape, to regulate the level of running of the tape with high precision. The rotating speeds of the capstans on both of the tape feed/take-up sides are regulated, whereby the tension of the tape is maintained at a desired prescribed value, to ensure a stable running of the tape.

Field of the Invention
The present invention relates to a magnetic tape driving apparatus for use in a magnetic recording and reproducing apparatus, and particularly to a magnetic tape driving apparatus which records and reproduces multichannel signals by a digital system by storing a pair of supply/take-up reels on which a magnetic tape is wound into a cassette, drawing out the magnetic tape from the cassette and running the magnetic tape in contact with a magnetic head of a stationary type capable of simultanouesly recording or reproducing signals of multiple tracks.

Magnetic tape driving apparatus with capstan rotating at different speeds


For applications in drug delivery, “smart” materials have been designed to respond to conditions within microenvironments of tissues or cells. The present invention features stimuli-responsive cross-linked hydrogels that respond to specific metabolites of disease. For example, protein-polymer materials of the present invention are configured to release their drug cargo upon encountering the higher lactate concentrations within tumor microenvironments.

Smart polymers are materials that respond to certain external stimuli. Stimuli responsive polymers are an efficient means of targeted therapy. Compared to conventional agents, they increase bioavailability and efficacy. In particular, polymer hydrogel nanoparticles (NPs) can be designed to selectively release their payload when exposed to a specific environment. The behavior of "smart" stimuli-responsive biomaterials is triggered by environmental conditions. In cancer therapy, polymers for drug delivery have typically been designed to respond to environmental conditions such as low pH (pH˜6-7 in the tumor extracellular microenvironment or pH˜5.5 in intracellular endosomes), slightly hyperthermic conditions in tumor tissues (only 1-2° C. above healthy tissues), or proteases. These biomaterials generally show benefit over traditional materials, but adequate in vivo therapeutic responses can sometimes be difficult to consistently achieve, partially because the differences between healthy and diseased environments are often not sufficiently large or unique. Alternative triggers, such as ultrasound, light, and magnetic force, require application of external conditions that may also be difficult to implement in internal tumor or tissues.
Cancerous tissues have a high lactic acid concentration, leading to a lower pH than normal, which can trigger NPs to release payloads. In 1924, Otto Warburg first observed that cancer cells metabolize glucose differently than normal cells, independent of whether oxygen was present (aerobic) or not (anaerobic) in the local environment, and these changes resulted in an accumulation of lactate in tumors. The Warburg effect is a result of an alternative metabolic pathway utilized by cancer cells and is now considered to be a hallmark of cancer. The vast majority of tumors accumulate lactate in its local environment through a metabolic shift from "normal" oxidative phosphorylation (via the TCA cycle) to aerobic glycolysis (with lactate production also being possible in tumors via the less-common anaerobic glycolysis). This shift to the glycolysis pathway, which produces lactate, is extensive and observed in the majority of different types of cancers. In cancer, genes in the glycolytic pathway are overexpressed in more than 70% of human cancer cases spanning 24 different classes of cancers, while overexpression is not observed for other biochemical pathways. Furthermore, the shift to aerobic glycolysis is so extensive that it is now utilized to identify cancer via positron emission tomography (PET) using fluorodeoxyglucose (FDG) as the glycolysis-reporting molecule. FDG PET has an 84-87% sensitivity of detecting cancer and a specificity of 88-93% across all oncology applications. It is now a standard clinical method of cancer detection, staging, and therapeutic assessment, highlighting the pervasiveness of this metabolic shift.
The Warburg effect has not yet been utilized in a drug release mechanism. However, because many diseases exhibit uniquely-altered metabolic pathways, the strategy of synthesizing metabolite-responsive materials has the potential of creating a new class of biomaterials and adding to the toolbox of stimuli-responsive biomaterials. Non-limiting examples of other disease-associated metabolites include succinate, indoxyl sulfate, and glutathione. The strategy of the present invention may be used to generate stimuli-responsive biomaterials specifically tailored for these or other disease associated metabolites.
Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one of ordinary skill in the art. Additional advantages and aspects of the present invention are apparent in the following detailed description and claims.

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA


A server establishes a secure session with a client device where a private key used in the handshake when establishing the secure session is stored in a different server. During the handshake procedure, the server receives a premaster secret that has been encrypted using a public key bound with a domain for which the client device is attempting to establish a secure session. The server transmits the encrypted premaster secret to the different server for decryption along with other information necessary to compute a master secret and session keys for the secure session. The different server decrypts the encrypted premaster secret, generates the master secret, and generates session keys that are used in the secure session for encrypting and decrypting communication between the client device and the server and transmits those session keys to that server.

Secure Sockets Layer (SSL) and Transport Layer Security (TLS), which is the successor to SSL, provide secure network connections. SSL and/or TLS are commonly used during web browsing (e.g., using HTTPS), email, and other Internet applications. SSL and TLS are described in several Request For Comments (RFCs), including RFC 2246 (describing TLS 1.0), RFC 4346 (describing TLS 1.1), RFC 5246 (describing TLS 1.2), and RFC 6101 (describing SSL 3.0).
An SSL or TLS client and server negotiate a set of parameters to establish a secure session in a process called a handshake. For example, the client transmits a hello message (referred to as a ClientHello message) that includes the following: an indication of the requested version of the SSL or TLS protocol, a requested session identifier used to identify the session connection, a list of the cipher suites (cryptographic options) supported by the client, a list of the compression methods supported by the client, random data used for cryptographic purposes (sometimes referred to as ClientHello.random), and may indicate whether and what type of extensions (defined by the protocol) the client supports.
In response, the server transmits a hello message to the client (referred to as a ServerHello message) that includes the version of the SSL or TLS protocol supported by the server, a session identifier that will be used to identify the session, the selected cipher suite (selected from the list of cipher suites included in the ClientHello message), the selected compression method (selected from the list of compression methods included in the ClientHello message), random data used for cryptographic purposes that is different than the random data included in the ClientHello message (sometimes referred to as ServerHello.random), and may include a list of the extensions that the server supports.
Following the hello messages, the server transmits a list of its certificate(s) in a message referred to as a Certificate message (sometimes referred to as a Server Certificate message). The server then transmits a message indicating that the hello-message phase of the handshake is complete (referred to as a ServerHelloDone message). For some implementations, depending on which key exchange methods are used (e.g., implementations using Diffie-Hellman cipher suites), the server also transmits a message to the client (referred to as a ServerKeyExchange message) that conveys cryptographic information to allow the client to calculate the premaster secret. This message is signed using the private key of the server. The client then transmits a message to the server (referred to as a ClientKeyExchange message) that includes a random value typically generated by the client called a premaster secret or Diffie-Hellman parameters that allows the client and server to agree upon the same premaster secret. The premaster secret is used by both the client and the server to generate a shared secret (referred to as the master secret) that is used to generate session keys that are used to encrypt and decrypt information during the secure session. If the premaster secret is included in the ClientKeyExchange message, it is encrypted using the public key in the certificate sent by the server. By way of a specific example, if the Rivest-Shamir-Adelman (RSA) algorithm is being used for key agreement and authentication, the client generates a 48-byte value for the premaster secret and encrypts it using the public key from the server's certificate and transmits the encrypted premaster secret to the server. By way of another specific example, if a Diffie-Hellman implementation is used, the ClientKeyExchange message includes the client's Diffie-Hellman public value. By way of another specific example, if a FORTEZZA hardware encryption system is being used, the client derives a token encryption key (TEK) using the FORTEZZA Key Exchange Algorithm (KEA), which itself uses the public key from the server's certificate along with private parameters of the client, generates a random 48-byte value for the premaster secret and encrypts it using the TEK and transmits the encrypted premaster secret to the server.
If the server receives the encrypted premaster secret in the ClientKeyExchange message, it decrypts it with their private key. In an implementation where the ClientKeyExchange message includes cryptographic parameters to generate the premaster secret, the server generates the premaster secret using those cryptographic parameters (which also requires the use of the private key).
The client and server each perform a series of steps to generate a master secret from the premaster secret, using the random data included in the ClientHello and ServerHello messages (e.g., the ClientHello.random and ServerHello.random). The master secret is a shared secret that is used to generate session keys, which are symmetric keys that are used to encrypt and decrypt information during the secure session.
The client then transmits a message to the server informing it that future messages will be encrypted (referred to as a ChangeCipherSpec message). The client then transmits an encrypted message to the server for validation (referred to as a Finished message). The server transmits to the client a message that future messages will be encrypted (a ChangeCipherSpec message) and an encrypted message to the client for validation (a Finished message). From then on, the handshake is complete and the secure session is established such that future messages between the client and server are encrypted.

This patent is subject to a terminal disclaimer.

Secure session capability using public-key cryptography without access to the private key


A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation.

1. Field of the Invention
The present invention relates to electrodes for solid oxide electrochemical cells and more specifically to a method of fabricating electrodes on solid oxide electrochemical cells by sintering. The electrochemical cells may include fuel cells, electrolyzers and sensors that operate on the basis of electromotive force measurement and/or current measurement and which comprise a solid oxide electrolyte and attached electrodes. Although this invention is primarily directed toward the fabrication of electrodes on fuel cells, it may also be used to fabricate electrodes on a variety of other electrochemical devices.
2. Background Information
Solid oxide fuel cells (SOFCs) are high temperature, electrochemical devices fabricated primarily from oxide ceramics. Typically, they contain an oxygen ion conducting solid electrolyte, such as stabilized zirconia. The electrolyte is usually a thin dense film which separates two porous electrodes comprising an anode and a cathode. The cathode, which is maintained in an oxidizing atmosphere, is usually oxide doped for high electrical conductivity, such as strontium doped lanthanum manganite. The anode, on the other hand, is maintained in a reducing atmosphere and is usually a cermet such as nickel-zirconia. Finally, an interconnection is usually employed which is a dense, electronically conducting oxide material which is stable in both reducing and oxidizing environments, such doped lanthanum chromite. The interconnection is deposited on a cell as a thin gas-tight layer in such a manner that it permits the anodes and cathodes of adjacent cells to be electrically connected in series. The gas-tightness of the interconnection, in combination with that of the electrolyte, insures that the entire cell is gas-tight, preventing mixing of the anode and cathode atmospheres.
Solid oxide cells can be operated in either an electrolysis mode or in a fuel cell mode. In an electrolysis mode, DC electrical power and steam or carbon dioxide or mixtures thereof are supplied to the cell which then decomposes the gas to form hydrogen or carbon monoxide or mixtures thereof, as well as oxygen. In the fuel cell mode, the cell operates by electrochemically oxidizing a gaseous fuel such as hydrogen, carbon monoxide, methane or other fuels to produce electricity and heat.
Nickel plus yttria-stabilized zirconia cermet fuel electrodes have been studied and used for many years as a means to improve thermal expansion match of the anode and electrolyte, and to minimize the effect of oversintering of nickel, which can result in poorer adherence due to a reduction of points of contact of nickel particles with the electrolyte, poorer electrochemical performance, and separation of the anode from the electrolyte during thermal cycles which can occur during fabrication and maintenance procedures. One type of Ni/YSZ cermet used in solid oxide fuel cells is made by coating a porous nickel particle layer covering the electrolyte with a layer of yttria-stabilized zirconia by an electrochemical vapor deposition (EVD) process at elevated temperature. This creates a zirconia skeleton encasing the nickel particles, giving a cermet that adheres tightly to the electrolyte and prevents spalling of the nickel from the electrolyte. This EVD process provides an excellent anode, but it is desirable to fabricate the anode with a less costly process.
The use of nickel-zirconia cermet anodes produced by EVD on solid oxide electrolyte fuel cells is exemplified in U.S. Pat. No. 4,490,444 to Isenberg. which provides an anode that is compatible in chemical, electrical and physical-mechanical characteristics such as thermal expansion with the solid oxide electrolyte to which it is attached. U.S. Pat. No. 4,597,170 to Isenberg addresses bonding and thermal expansion problems between the anode and solid oxide electrolyte by use of a skeletal embedding growth of, for example, ionically conducting zirconia doped with minor amounts of yttria. The skeletal growth extends from the electrolyte/anode interface into a porous nickel layer. U.S. Pat. No. 4,582,766 to Isenberg discloses oxidizing the nickel in a cermet electrode to form a metal oxide layer in order to reduce gas diffusion overvoltages.
Although attempts have been made at producing cermet anodes by low-cost sintering techniques rather than EVD processes, such sintered anodes often deteriorate during operation, which may be related to continued sintering, poor adherence to the electrolyte at useful anode sheet resistance values, and low porosity at suitable resistivity values. Conventional sintering processes are disclosed in U.S. Pat. Nos. 4,971,830 and 5,035,962 to Jensen.
Each of the patents cited above is incorporated herein by reference.
Despite the foregoing efforts, there is still a need for a low cost sintering process for the fabrication of anode structures which eliminates the need for electrochemical vapor deposition, while providing the desired combination of conductivity, adherence, electrochemical performance and stability over a long period of time.

Sintered electrode for solid oxide fuel cells