Multilayer Ceramic Capacitors with Thin (Ba,Sr)TiO3 Layers by MOCVD

Barium strontium titanate ((Ba,Sr)TiO₃; BST) thin films were prepared on platinum-coated MgO substrates at 650°C by metalorganic chemical vapor deposition (MOCVD). Perovskite single phased BST thin films were obtained. Dielectric constant at 1 kHz–100 mV was 1000. Multilayer ceramic capacitor with twelve BST dielectric layers of 0.26 m thick was formed on the MgO substrate. Capacitance and dissipation factor (tan) at 1 kHz–100 mV were 32 nF and 1.5% respectively. Capacitance per unit volume of 33 F/mm³ provided 10 to 20 times larger volumetric efficiency than the conventional multilayer ceramic capacitors. Temperature coefficient of capacitance was –4000 ppm/°C. The leakage current at 1 V was 2.3×10^-9 A that yielded an acceptable CR product of 12.8 M-F. MOCVD was proposed as one of the promising manufacturing technologies for multilayer ceramic capacitors of high performance with sub-micron thick dielectric layers.     

Reconstruction of an object from its Fourier modulus: development of the combination algorithm composed of the hybrid input-output algorithm and its converging part

The hybrid input-output algorithm (HIO) used for phase retrieval is in many cases combined with the error-reduction algorithm (ER) to attempt to stabilize the HIO. However, in our previous paper [J. Opt. Soc. Am. A 16, 2163 (1999)], it was demonstrated that this combination makes it more likely that the resultant algorithm will fall into a periodic state before reaching a solution because the values of the input object outside the support, which is imposed as the object-domain constraint, are set to be zero in the intervals in which the ER is implemented. This paper deals with this problem inherent in the combination algorithm. The converging part of the HIO (CPHIO), which is an algorithm we previously developed [J. Opt. Soc. Am. A 15, 2849 (1998)], can be thought of as an extension of the ER for the case in which the input object can have nonzero values outside the support. Keeping this in mind, the algorithm is then constructed by combining the HIO with the CPHIO instead of with the ER. The computer simulation results that demonstrate the effectiveness of the proposed algorithm are given.     

A silicon‐chip‐based light valve with reflective twisted‐nematic mode for high‐definition projectors

Crystalline‐silicon‐chip‐based reflective light valves are suitable for realizing high definition and bright liquid‐crystal projectors. We have developed an XGA (1025 × 769 pixels) silicon‐chip‐based light valve with a diagonal display area of 2.54 cm (1 in.). The reflective twisted‐nematic mode was examined by using the Jones matrix method as a display mode, and the normally white reflective twisted‐nematic mode was selected. This mode is suitable for a narrow cell gap, and a fast response time can be expected. In addition, the driving voltage of this mode is low and has good chromaticity with small retardation. The cell gap of the light valve is 2 μm. The cell gap support is made using spacer posts formed on the silicon chip with a photodefinable resin. The response time is 12 msec, including both rise and fall times. The contrast ratio is more than 1000 at 5 Vrms.     

Pore size control technique in the spinning of polysulfone hollow fiber ultrafiltration membranes

Conditions for finger-like void formation in polysulfone (PS) ultrafiltration membranes were studied empirically. It was found that both the “mixability parameter” which was obtained in separate titration experiments and the viscosity of coagulants could be used to predict membrane morphology. It was also found that finger-like void layers appeared under the conditions which dope had concentrations quite apart from the phase separation area and which coagulant had both a low mixability parameter and low viscosity.

These factors proved to play a very important role in controlling the pore size of membranes. The results of this study were applied to obtaining pore size variations of PS hollow fiber membranes.     

HIF-1α Dependent Upregulation of ZIP8, ZIP14, and TRPA1 Modify Intracellular Zn2+ Accumulation in Inflammatory Synoviocytes

Intracellular free zinc ([Zn²⁺]_i) is mobilized in neuronal and non-neuronal cells under physiological and/or pathophysiological conditions; therefore, [Zn²⁺]_i is a component of cellular signal transduction in biological systems. Although several transporters and ion channels that carry Zn²⁺ have been identified, proteins that are involved in Zn²⁺ supply into cells and their expression are poorly understood, particularly under inflammatory conditions. Here, we show that the expression of Zn²⁺ transporters ZIP8 and ZIP14 is increased via the activation of hypoxia-induced factor 1α (HIF-1α) in inflammation, leading to [Zn²⁺]_i accumulation, which intrinsically activates transient receptor potential ankyrin 1 (TRPA1) channel and elevates basal [Zn²⁺]_i. In human fibroblast-like synoviocytes (FLSs), treatment with inflammatory mediators, such as tumor necrosis factor-α (TNF-α) and interleukin-1α (IL-1α), evoked TRPA1-dependent intrinsic Ca²⁺ oscillations. Assays with fluorescent Zn²⁺ indicators revealed that the basal [Zn²⁺]_i concentration was significantly higher in TRPA1-expressing HEK cells and inflammatory FLSs. Moreover, TRPA1 activation induced an elevation of [Zn²⁺]_i level in the presence of 1 μM Zn²⁺ in inflammatory FLSs. Among the 17 out of 24 known Zn²⁺ transporters, FLSs that were treated with TNF-α and IL-1α exhibited a higher expression of ZIP8 and ZIP14. Their expression levels were augmented by transfection with an active component of nuclear factor-κB P65 and HIF-1α expression vectors, and they could be abolished by pretreatment with the HIF-1α inhibitor echinomycin (Echi). The functional expression of ZIP8 and ZIP14 in HEK cells significantly increased the basal [Zn²⁺]_i level. Taken together, Zn²⁺ carrier proteins, TRPA1, ZIP8, and ZIP14, induced under HIF-1α mediated inflammation can synergistically change [Zn²⁺]_i in inflammatory FLSs.     

Utilization of stereo disparity and optical flow information for the computer analysis of human interactions

We propose a system that simultaneously utilizes the stereo disparity and optical flow information of real-time stereo grayscale multiresolution images for the recognition of objects and gestures in human interactions. For real-time calculation of the disparity and optical flow information of a stereo image, the system first creates pyramid images using a Gaussian filter. The system then determines the disparity and optical flow of a low-density image and extracts attention regions in a high-density image. The three foremost regions are recognized using higher-order local autocorrelation features and linear discriminant analysis. As the recognition method is view based, the system can process the face and hand recognitions simultaneously in real time. The recognition features are independent of parallel translations, so the system can use unstable extractions from stereo depth information. We demonstrate that the system can discriminate the users, monitor the basic movements of the user, smoothly learn an object presented by users, and can communicate with users by hand signs learned in advance. Received: 31 January 2000 / Accepted: 1 May 2001 Correspondence to: I. Yoda (e-mail: yoda@ieee.org, Tel.: +81-298-615941, Fax: +81-298-613313)     

Improvement in the oxidation resistance of TiAl by preoxidation in a TiO2-powder pack

The resistance of TiAl coupons to cyclic oxidation at 1300 K in a flow of purified oxygen under atmospheric pressure has been significantly improved by preoxidation. The preoxidation was performed by heating the specimens, buried in rutile powder and encapsuled in a silica tube under a vacuum of 1.3×10^–3 Pa, at 1200 K for 100ks. The scales formed by preoxidation are very adherent, and the mass changes are very small for at least up to 20 cycles (400 h) of subsequent oxidation. This excellent oxidation resistance is attributable to the formation of scales very rich in alumina by preoxidation under a very low oxygen partial pressure. A similarly good oxidation resistance was obtained when the specimens were buried in rutile powder and preoxidized in Ar gas under atmospheric pressure at 1300 K for 100 ks.     

Photocatalytic properties of layered hydrous titanium oxide/CdS?ZnS nanocomposites incorporating CdS?ZnS into the interlayer

H₂Ti₄O₉/Cd_0·8Zn_0·2S nanocomposites incorporating Cd_0·8Zn_0·2S particles, less than 1 nm in thickness, were fabricated by the chemical reaction between a Cd²⁺–Zn²⁺ mixture and H₂S in the interlayer of H₂Ti₄O₉. H₂Ti₄O₉/Cd_0·8Zn_0·2S nanocomposites were capable of efficient hydrogen evolution following irradiation with visible light in the presence of Na₂S as a sacrificial donor. The hydrogen production activity of the H₂Ti₄O₉/Cd_0·8Zn_0·2S nanocomposite was superior to those of unsupported Cd_0·8Zn_0·2S and the mixture of H₂Ti₄O₉ and Cd_0·8Zn_0·2S. The hydrogen production was enhanced by doping Pt together with Cd_0·8Zn_0·2S in the interlayer, but was depressed by depositing Pt on the outer surface of the H₂Ti₄O₉/Cd_0·8Zn_0·2S nanocomposite.