Influence of effective surface area on gas sensing properties of WO3 sputtered thin films

WO₃ thin films having different effective surface areas were deposited under various discharge gas pressures at room temperature by using reactive magnetron sputtering. The microstructure of WO₃ thin films was investigated by X-ray diffraction, scanning electron microscopy, and by the measurement of physical adsorption isotherms. The effective surface area and pore volume of WO₃ thin films increase with increasing discharge gas pressure from 0.4 to 12 Pa. Gas sensors based on WO₃ thin films show reversible response to NO₂ gas and H₂ gas at an operating temperature of 50-300 °C. The peak sensitivity is found at 200 °C for NO₂ gas and the peak sensitivity appears at 300 °C for H₂ gas. For both kinds of detected gases, the sensor sensitivity increases linearly with an increase of effective surface area of WO₃ thin films. The results demonstrate the importance of achieving high effective surface area on improving the gas sensing performance.     

All solid-state sheet battery using lithium inorganic solid electrolyte, thio-LISICON

All solid-state sheet lithium battery was developed using inorganic solid electrolyte, thio-LISICON (Li_3.25Ge_0.25P_0.75S₄), Li–Al anode, and Mo₆S₈ cathode materials, and the sheet manufacturing process was established. The new sheet-configuration was consisted of the cathode with the grid of current collector, electrolyte sheet with or without mechanical support, and aluminum/lithium composite sheet anode. A sheet battery with a dimension of 30 mm × 30 mm showed good charge–discharge characteristics without any capacity fading at a current of 0.1 mA.     

Improved method to simulate gradient in alumina packing fraction in alumina/epoxy composite fabricated by a centrifugal method

A centrifugal method was used to fabricate large‐scale functionally graded materials (FGMs) from solid‐particles/viscous‐matrix mixtures at room temperature. The conventional simulation procedure of the centrifugal process was improved by considering the dependency of the viscosity η of the mixture on the packing fraction ν_p of particle, the effects of arbitrary shape of the actual fillers on η, the statistical dispersion of the diameters of the actual fillers, and the formation and growth of the fully packed layer (FPL) near the FGM bottom. The new simulation method was applied to three centrifugal processes employed for experimental FGM fabrications from alumina/epoxy mixtures. The numerical profiles of ν_p are in good agreement with the experimental ones regardless of the shapes of fillers and 'ponding viscosity of the solutions without fillers, the total amount of fillers loaded, and the centrifugal conditions. The saturating nature of ν_p near the far end of the FGM column is also simulated with reasonable precision. Finally, the manner in which the particles exert varying influences on the gradient of ν_p is demonstrated: the particles exhibit different movements depending on their size. On the basis of these results, the effectiveness of the new simulation method proposed is confirmed for the modeling of similar processes involved in the fabrication of FGMs from solid‐particles/viscous‐matrix mixtures by the centrifugal method. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A study on hot carrier effects on N-MOSFETs under high substrate impurity concentration

A systematic investigation of the influences of high substrate doping on the hot carrier characteristics of small geometry n-MOSFETs down to 0.1 /spl mu/m has been carried out. Results indicate that the dependence of substrate current and impact ionization rate on substrate impurity concentration is reversed in long channel and short channel devices. In the long channel case, both increase with rising substrate impurity concentration, while they decrease in the case of short channel devices. An explanation for this phenomenon based on the lucky electron model has been developed. The dependence of other characteristics on impurity concentration has also been studied. The dependence of off-leakage current has been found to fall as the gate oxide is reduced in thickness. Regarding the dependence of hot carrier degradations, the degradation of drain currents becomes smaller as the substrate impurity concentration increases in the case of short channel devices. Further, in the extremely high impurity doping region, a new hot carrier degradation mode was found, in which the maximum transconductance values of n-MOSFETs increase after hot carrier stress. This new degradation mode can be explained in terms of effective channel length shortening caused by electron trapping.<>     

Competitive interaction of polyanions and anionic dye with bovine serum albumin

The binding of anionic dye, p-(2-amino-6-sulfonyl-8-naphthylazo)benzene sulfonic acid disodium salt (ASANA) to bovine serum albumin (BSA) at pH 7.5 has been studied by spectrophotometric techniques. The values of the dissociation constants were obtained with the use of the Benesi-Hildebrand equation for ASANA. Competitive binding of polyanions, sodium poly(styrene sulfonate) (PSSNa), potassium poly(vinyl sulfonate) (PVSK), poly(acrylic acid) (PAA), and poly(methacrylic acid) (PMAA) and anionic dye to BSA was evaluated through the variations in the different spectra of BSA-dye-polymer systems.     

Examination of simple analytical method for calculating 60-Hz magnetic field in power substations

In the last decade, increasing attention has been paid to ELF (Extremely Low Frequency) electromagnetic environments in work areas as well as in and near homes, regarding their interaction both with electric apparatus such as CRT's and with biological systems. Experimental and theoretical analyses are presented of 60 Hz magnetic field (B-field) characteristics at and near ground level in both 187/66-kV EHV and 66/6.6-kV HV power substations. Experimental results of B-field profiles along horizontal paths as well as harmonic contents in B-field waveforms at several positions are shown and discussed. Furthermore, analytical B-field profiles calculated by using a B-field approximation method based on Biot-Savart law are shown and compared with the measured ones. The comparisons verify that the assumptions employed are applicable to the substation B-field calculation, and that the B-field calculation method employed can estimate B-field in EHV and HV power substation to significant accuracy, except for areas where localized B-field sources, such as power transformers and underground power cables, exist. The analytical profiles of three orthogonal components of B-field are also described in terms of equiflux contour maps, which show 3-D characteristics of B-field in power substations.     

Mixed mode fracture criterion of interface crack between dissimilar materials

This study presents an application of fracture mechanics to the interface crack between dissimilar materials. In this study, a concept of the stress intensity factors of an interface crack is discussed, and various types of specimens are tested experimentally for investigating the mixed mode fracture toughness criterion of an interface crack. The fracture toughness based on the stress intensity factors of an interface crack is decided by the fracture test and the boundary element analysis using the contour integral method. The mixed mode fracture toughness criterion is successfully characterized by the stress intensity factors of an interface crack.     

Automated generation of simply connected solid objects from wire-frame data using operations on graphs

This paper presents an algorithm for the automatic generation of solid objects from three-dimensional wire-frame data. In this work, as we mainly use topological information of wire-frame data, we can achieve high-speed execution and adapt this algorithm to free-from surfaces. We present the conversion algorithm and show several experimental results.     

Translator knowledge base for machine translation systems

This paper presents a new method for utilizing translator knowledge bases for machine translation systems. Translator knowledge to be stored and utilized consists of translationally equivalent pattern pairs: surface-level phrasal, clausal, and sentential correspondences between the source and target languages. This knowledge will be utilized to translate domain-specific idiomatic, nonstandard, or ungrammatical expressions. The proposed method has been implemented in an adaptive English to Japanese machine translation system, HICATS/EJ, as one of its customization facilities.