Luminescent properties of ZnCdSe/ZnMnSe superlattices

Zn_0.91Cd_0.09Se/Zn_0.82Mn_0.18Se superlattices were grown by molecular beam epitaxy with well layer thicknesses of 4–35 Å and a barrier layer thickness of 12 Å. Magneto-luminescence was measured in the Faraday geometry in the temperature range of 10–100 K. The Zeeman shifts of the excitonic emissions from the superlattices were analyzed as a function of well layer thickness by using Kronig–Penny model, in which the conduction and valence band offsets were modulated by external magnetic field. Paramagnetism enhancement of ZnMnSe at the interface with nonmagnetic layer and Mn diffusion at the heterointerface were taken into consideration. The Mn diffusion showed a crucial effect on the Zeeman shift of the superlattice system.     

Characterisation of volatile and non-volatile metabolites in etiolated leaves of tea (Camellia sinensis) plants in the dark

Aroma is an essential factor affecting the quality of tea (Camellia sinensis) products. While changes of volatile compounds during tea manufacturing have been intensively studied, the effect of environmental factors on volatile contents of fresh tea leaves has received less attention. We found that C. sinensis var. Yabukita kept in darkness by shading treatment for 3 weeks developed etiolated leaves with significantly increased levels of volatiles, especially volatile phenylpropanoids/benzenoids (VPBs). Upstream metabolites of VPBs, in particular shikimic acid, prephenic acid, and phenylpyruvic acid, showed lower levels in dark treated than in control leaves, whereas the contents of most amino acids including l-phenylalanine, a key precursor of VPBs, were significantly enhanced. In addition, analysis by ultra performance liquid chromatography-time of flight mass spectrometry, capillary electrophoresis–time of flight mass spectrometry, high performance liquid chromatography, and gas chromatography–mass spectrometry indicated that volatile and non-volatile metabolite profiles differed significantly between dark treated and untreated leaves.     

Construction and electrochemistry of Langmuir-Blodgett films of fullerene lipid composite/hybrid materials

Studies of the electrochemistry of Langmuir-Blodgett (LB) films of C70/artificial lipids including tridodecylmethylammonium bromide (3C12N+Br-, 1), didodecylphosphate (2C12PO4H, 2), and dioleoylphosphatidylcholine (DOPC, 3) and of LB films of a fullerene lipid (4) bearing triple alkyl chains on a C60 moiety on electrodes were carried out in aqueous media. Stable Langmuir monolayers of fullerene C70/artificial lipid composites and the fullerene lipid (4) were formed at the air-water interface and these monolayers were transferred onto electrodes as LB films. Here, we focus on the importance of cationic matrix lipid films to the facile electrochemistry of C70 embedded in a LB film of cationic lipids on an electrode in aqueous media. On the basis of the electrolyte dependence and the charge dependence of the matrix lipids, a possible electron-transfer mechanism of the C70/artificial lipid LB film-modified electrodes is presented. Electrochemistry of a LB film of 4 was also obtained in an aqueous medium. We demonstrate that the introduction of the chemistry of lipid bilayer membranes to the LB films of fullerenes guides us toward the construction of fullerene/lipid bilayer devices.     

Monte Carlo calculations on vector supercomputers using GMVP

A multigroup general purpose Monte Carlo code GMVP has been developed. The vectorization algorithm is based on a stack-driven zone selection method. GMVP can treat repeated rectangular and hexagonal lattices together with combinatorial geometry which is quite useful to achieve a high gain by vectorization. The performance of the code was evaluated by solving various types of problems. In addition, the continuous energy code is under development and the performance is compare with conventional codes. The code was installed on other four different supercomputers to investigate portability and computer dependence of code performance.     

Double sinusoidal phase-modulating distributed-Bragg-reflector laser-diode interferometer for distance measurement

A previously proposed double sinusoidal phase-modulating (DSPM) laser-diode interferometer measures distances larger than a half-wavelength by detecting modulation depth. Although it requires a vibrating mirror to provide the second modulation to the interference signal, such vibrations naturally affect measurement accuracy. We propose a static-type DSPM laser-diode interferometer that uses no mechanical modulation. Our experimental results indicate a measurement error of +/- 1.6 microm.     

Double-grating interferometer for measurement of cylinder diameters

We describe a double-grating interferometer for the measurement of cylinder diameters. The unique characteristic of this interferometer is that one can freely change the period of the interference fringes by turning the grating, which permits the measurement range of the interferometer also to be changed freely according to the cylinder diameter to be measured. A clear image of the cylinder can be obtained because the aperture diaphragm blocks the beams diffracted from the edge of the cylinder. The outside and inside diameters of the M4 x 0.7 mm hand tap are measured with this double-grating interferometer.     

Solid hydrogen Raman shifter for the mid-infrared range (4.4-8 microm)

We developed a pulsed, continuously tunable laboratory laser source for the mid-infrared spectral range of 4.4-8 microm, which is characterized by the spectral linewidth of 0.4 cm(-1). The device is based on the stimulated backward Raman scattering in solid para-hydrogen at T = 4 K. It is pumped by a focused beam obtained from a commercial near-infrared optical parametric oscillator with output energy of approximately 20 mJ (7-ns pulse). Output energies range from 1.7 mJ at 4.4 microm to 120 microJ at 8 microm, which correspond to quantum efficiencies of 0.53 and 0.08, respectively. Spectra of NO, H2O, and CH4 molecules in the mid-infrared were recorded. The operation of the Raman cell pumped with 532-nm radiation was also studied.     

Volume Contents

Volume Contents

Volume Contents     

An experimental study on aerodynamic sound generated from wake interference of circular cylinder and airfoil vane in tandem

The purpose of this study is to investigate the characteristics of aerodynamic sound generated from wake inter-ference of circular cylinder and airfoil vane located in tandem and to clarify the generation mechanism of thesound source with discrete frequency.The effects of the interval between the cylinder and the airfoil on the char-acteristics of aerodynamic sound are investigated by acoustic measurement,flow visualization and explorationtest of sound source.The relation between the flow field and the sound field with discrete frequency noise(DFN)is shown,and then it is found that the downstream airfoil works as the sound source of DFN,which has the fre-quency of vortex shedding from the upstream cylinder,when the interval of two bodies is longer than a criticaldistance.