Radiation-induced graft copolymerization of mixtures of styrene and n-butyl acrylate onto cellulose and cellulose triacetate

Mixtures of styrene and n-butyl acrylate of various compositions were grafted onto cellulose and cellulose triacetate fibers preirradiated with γ-rays at 0°C in air. Monomer reactivity ratios of the grafted copolymers were found to be different from those of the nongrafted copolymers or those of AIBN-initiated copolymers. The active species initiating the graft copolymerization were trapped radicals for cellulose and peroxides for cellulose triacetate. Kinetic investigations of the graft copolymerization of styrene onto preirradiated cellulose triacetate fibers were also carried out, and it was found that the kinetic scheme for radical polymerization is also applicable to graft copolymerization in a heterogeneous system.     

Moiré‐reduction methods for integral videography autostereoscopic display with color‐filter LCD

Abstract— Moiré‐reduction methods for integral videography displays are proposed. Integral videography is based on the principles of integral photography and extended real‐time video processing. There are two moiré‐reduction methods that can be used for integral videography displays that have a lens array and a liquid‐crystal display. The first is color moiré, and the second is intensity moiré. To reduce color moiré, an optimized color‐filter layout in the liquid‐crystal display was used. To reduce intensity moiré, a defocusing method was used. Adesign of a viewing area for the integral videography display is also presented. To control the viewing area, the lens pitch and the shape of the integral videography elemental image was changed. A 5‐in. integral videography display was implemented by using the proposed methods, and an integral videography display was evaluated.     

Metamorphic Heterostructure InP/GaAsSb/InP HBTs on GaAs Substrates by MOCVD

Good-quality metamorphic InP buffer layers have been successfully grown on GaAs substrates by metal-organic chemical vapor deposition. Characterization by atomic force microscope, transmission electron microscopy, high-resolution X-ray diffraction, and Hall measurements indicated that the layers are of high crystalline quality, good mobility, and excellent surface morphology. On this buffer, we demonstrated the first metamorphic InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) with good material quality and device performance. Metamorphic DHBTs showed direct-current and radio-frequency characteristics that are comparable to those grown on lattice-matched InP substrates.     

Preparation of calcium-doped boron nitride by pulsed laser deposition

Calcium-doped BN thin films Ca_xBN_y (x = 0.05–0.1, y = 0.7–0.9) were grown on α-Al₂O₃(0 0 1) substrates by pulsed laser deposition (PLD) using h-BN and Ca₃N₂ disks as the targets under nitrogen radical irradiation. Infrared ATR spectra demonstrated the formation of short range ordered structure of BN hexagonal sheets, while X-ray diffraction gave no peak indicating the absence of long-range order structure in the films. It was notable that Ca-doped film had 5.45–5.55 eV of optical band gap, while the band gap of Ca-free films was 5.80–5.85 eV. This change in the band gap is ascribed to interaction of Ca with the BN sheets; first principle calculations on h-BN structure indicated that variation of inter-plane distance between the BN layers did not affect the band gap. This study highlights that PLD could prepare BN having short-range structure of h-BN sheets and being doped with electropositive cation which varies the optical band gap of the films.     

Effects of the thermal history on the hydraulic properties of slags

Glasses with two composition in the CaO---Al₂O₃---SiO₂ system were prepared with different cooling conditions. Glass A has a eutectic composition of wollastonite-gehlenite-rankinite and glass B has that of wollastonite-gehlenite-anorthite. The effects of the thermal history on the structure and hydraulic properties were discussed. Effects of cooling rate on the physical and chemical properties of glasses are found to be different with chemical composition of glass. Cooling rate affects the hydraulic reactivity and crystallization temperature, especially in glass A, but scarcely affects the physical properties such as chemical shift of AlK and surface basicity of the glass.     

Laser-Sintered Barium Titanate

Laser sintering of alkoxy-derived ultrafine BaTiO₃ powders was investigated. The temperature increases of the sample with laser irradiation were measured with a thermocouple. It was found that laser irradiation could generate enough heat to sinter ceramics. A slurry was prepared by mixing an alkoxy-derived BaTiO₃ powder, binder additives, solvent, and plasticizer. The slurry was tape cast and dried to give a green sheet. The green sheet was laser sintered and was then characterized by SEM, XRD, and density measurements. The effect of burnout before laser irradiation and the characteristic microstructure of laser-sintered BaTiO₃ are described.     

Environmental protection: researches in National Institute of Radiological Sciences

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.     

ε-Entropy and Fractal Dimension of a State for a Gaussian Measure

Kolmogorov introduced the concept of -entropy to analyze information in classical continuous systems. The fractal dimension of a geometric set was introduced by Mandelbrot as a new criterion to analyze the geometric complexity of the set. The -entropy and the fractal dimension of a state in a general quantum system were introduced by one of the present authors (MO) in order to characterize chaotic properties of general states.In this paper, we show that -entropy of a state includes Kolmogorov's -entropy, and that the fractal dimension of a state describes fractal structure of Gaussian measures.     

Analysis of proton exchange membrane fuel cell catalyst layers for reduction of platinum loading at Nissan

The biggest issue that must be addressed in promoting widespread use of fuel cell vehicles (FCVs) is to reduce the cost of the fuel cell system. Especially, it is of vital importance to reduce platinum (Pt) loading of catalyst layers (CLs) in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC). In order to lower the Pt loading of the MEA, mass transport of reactants related to the performance in high current density should be enhanced significantly as well as kinetics of the catalyst, which can result in the better Pt utilization and effectiveness. In this study, we summarized our analytical approach and methods for reduction of Pt loading in CLs. Microstructure, mass transport properties of the reactants, and their relation in CLs were elucidated by applying experimental analyses and computational methods. A simple CL model for I–V performance prediction was then established, where experimentally elucidated parameters of the microstructure and the properties in CLs were taken into account. Finally, we revealed the impact of lowering the Pt loading on the transport properties, polarization, and the I–V performance.