Analysis of nonlinear transient responses of piezoelectric resonators

The electric transient response method is an effective technique to evaluate material constants of piezoelectric ceramics under high-power driving. In this study, we tried to incorporate nonlinear piezoelectric behaviors in the analysis of transient responses. As a base for handling the nonlinear piezoelectric responses, we proposed an assumption that the electric displacement is proportional to the strain without phase lag, which could be described by a real and constant piezoelectric e-coefficient. Piezoelectric constitutive equations including nonlinear responses were proposed to calculate transient responses of a piezoelectric resonator. The envelopes and waveforms of current and vibration velocity in transient responses observed in some piezoelectric ceramics could be fitted with the calculation including nonlinear responses. The procedure for calculation of mechanical quality factor Q(m) for piezoelectric resonators with nonlinear behaviors was also proposed.     

Photosensitized hydrogen evolution from water using a single-walled carbon nanotube/fullerodendron/SiO2 coaxial nanohybrid

A coaxial nanohybrid consisting of a single-walled carbon nanotube (SWCNT), fullerodendron, and SiO(2) shows high-efficiency light-driven hydrogen evolution from water. Upon visible light irradiation, SWCNT/fullerodendron/SiO(2) coaxial nanohybrid shows hydrogen evolution activity in the presence of methyl viologen (MV(2+)), benzyldihydronicotinamide (BNAH), and a colloidal polyvinyl alcohol(PVA)-Pt.     

Novel screening system for protein-protein interactions by bimolecular fluorescence complementation in Saccharomyces cerevisiae

For high-throughput screening of protein-protein interactions, we have developed a novel yeast screening system using Bimolecular fluorescence complementation (BiFC). Two yeast plasmids, in which genes of heterodimerized peptides LZA and LZB were each fused with those of non-fluorescent half fragments of Kusabira-Green mutant (mKG2), were transformed into a- and α-type yeast, respectively. Mating of them gave a library, which was screened by following green fluorescence resulted from LZA-LZB interaction. The method showed potential ability to detect the positive clones from a model library, in which green-fluorescent and non-fluorescent yeast was mixed in a ratio of 1:675.     

ON THE SPECIFIC RESISTANCE OF CAKES OF MICROORGANISMS

The mean specific resistance of the cakes of various microorganisms was evaluated by measurement of either a change in the amount of permeate with time or of steady-state flux under constant pressure. The mean specific resistance was different with different shapes and sizes of microorganisms. The large differences arose from different packing structures of the cake. The effect of a filter aid on the filtration rate and cake structure was studied experimentally and theoretically. The effects of a filter aid were best explained by a series model, in which a cake layer composed of microbial cells and a layer of randomly distributed microbial cells and filter aid are packed on the membrane surface in series with respect to the directions of permeation.     

Studies on the solid solutions,LnV1−xMxO3 (Ln:La,Gd or Y,M:Cr or Fe)

Electrical and magnetic properties of the solid solutions LnV_1?xM_xO₃ (Ln:La, Gd or Y, M:Cr or Fe) were studied in the temperature range 77–1000K. These solid solutions were all semiconductors. Their conductivity at room temperature decreased with Cr³⁺ or Fe³⁺ ion concentrations. The solid solutions LaV_1?xM_xO₃ and YV_1?xM_xO₃ (M:Cr or Fe) revealed an antiferromagnetism with a weak ferromagnetism and their ordering temperature increased with x. Most of the gadolinium-containing compounds were paramagnets in the measured temperature range. YV_0.4Fe_0.6O₃ showed a thermal hysteresis at high temperatures.     

New transverse-domain formation mechanism in aquarter-micrometre-gate HEMT

Studies a quarter-micrometre-gate HEMT by a two-dimensional Monte Carlo particle simulation to gain a deeper insight into the device operation. A new transverse-domain formation due to intervalley electron transfer is predicted. The effect of domain formation on device performance and current saturation characteristics is also discussed     

Temperature distribution in Li2O pellets under neutron irradiation

The center temperature of Li₂O pellets under neutron irradiation was measured using an encapsuled pin. The surface temperatures of the pellets and the pellet/cladding heat transfer coefficients were estimated on the basis of the well-known conductivity integral.     

Post-irradiation studies on knock-out and pseudo-recoil releases of fission products from fissioning UO2

By using post-irradiation techniques, in-pile releases of ¹³³Xe, ^85mKr, ⁸⁸Kr, ⁸⁷Kr and ¹³⁸Xe from UO₂ fissioning at low temperatures below about 200° C are studied: these are analyzed into a time-dependent knock-out and time-independent pseudo-recoil releases. For the latter, a “self knock-out” mechanism is proposed: when a fission fragment loses thoroughly its energy near the UO₂ surface and stops there, it will knock out the surface substances and accordingly the fragment (i.e. the fission product) will be released. The effective thickness of the layer where the self knock-out occurs is found to be ~7Å. As for the knock-out release, the following is estimated from its dependence on various factors: the knock-out release of fission products occurs from the surface layer with the effective thickness of ~20Å: the shape of UO₂ matrix knocked out by one fission fragment passing through the surface is equivalent to a cylinder ~32Å diameter by ~27Å thick, (i.e. the knock-out coefficient for UO₂ is ~660 uranium atoms per knock-out event). On the basis of the above estimations, the conclusions derived from the past in-pile studies of fission gas releases are evaluated.     

Modulation characteristics of 1.3 ?m buried-stripe InGaAsP laser up to 2 Gbit/s data rates

Modulation experimenting on a buried-stripe (b.s.) InGaAsP laser emitting at 1.3 ?m was carried out up to 2 Gbit/s. The b.s. laser is free from relaxation oscillation, which degrades modulated optical pube waveforms, especially at high data rates. The repeater gain of 1.6 Gbit/s transmission systems is improved by 9 dB compared with previously reported experiments. Modulation characteristics up to 2 Gbit/s are reported.     

Monte Carlo particle simulation of a GaAs short-channel MESFET

A Monte Carlo particle simulation of a 0.25 ?m-long gate (and 0.25 ?m-long channel) GaAs MESFET having a practical doping density and sitting on a substrate is carried out. Extremely high values of gm and Idss of 643 mS/mm and 5.35 mA/20 ?m were obtained. The near-ballistic nature of the electron transport in the FET was confirmed.