Anomalous anisotropic deformations of As2S3 flakes induced by linearly-polarized bandgap illumination

Semi-free As₂S₃ flakes undergo visible-scale anisotropic deformations when exposed to linearly-polarized bandgap illumination. We investigate the behavior and also those in amorphous Se, GeS₂, AgAsS₂, and crystalline As₂S₃. These results suggest that the deformation occurs through photo-induced birefringence, photo-induced fluidity, and optical force.     

Precise determination of rare earth elements in rocks by neutron activation analysis

A pre-irradiation group separation method has been developed for the neutron activation analysis of rare earth elements (REE) and Ba in silicate rocks. REE and Ba were quantitatively separated from other elements by cation exchange column method. The chemical yield of each separation was monitored with Pr added to the sample powder before decomposition. The accuracy and precision were tested by repeated analyses of JB-1 and one analysis of BCR-1. In addition, it was found that REE distribution in a granitic rock powder was inhomogeneous and therefore special care must be taken for the sampling of granitic rock powders.     

A gamma-ray approach for hidden faults in the disaster zone of 1995 Kobe earthquake

Gamma-ray intensities were measured of the ground on an eastern part of the Kobe urban area, where a strong earthquake occurred in January 1995 killing 6000 people, in order to investigate hidden faults and its relation to the damage of constructions. Several linear alignments of relatively high -ray intensity points were detected and at least some of them are considered to be ascribed to small-scale faults. It can be pointed out that the localities of such high -ray alignments are almost in accordance with those of relatively highly damaged zones. However, a long and distinct high -ray alignment as expected for a large fault which runs through the heavy damage belt does not exist beneath the area, supporting non-fault origin for the overall heavy damage belt.     

Nucleotide sequences of membrane-bound hydrogenase gene in Alcaligenes hydrogenophilus.

The nucleotide sequences of membrane-bound hydrogenase small (hupS) and large (hupL) subunit genes of hydrogen bacterium Alcaligenes hydrogenophilus were determined. The hupS and hupL genes encoded polypeptides of 363 and 619 amino acids, respectively. The hupS was located upstream of hupL with 35bp of intergenic region. The consensus ribosome-binding sequences were identified upstream of the start codons of hupS and hupL. Amino acid sequence of hupS is very similar to that of Rhodobacter capsulatus, Bradyrhizobium japonicum, and Azotobacter vinelandii at amino acid levels of 82%, 77%, and 81%, respectively. Similarly, amino acid sequence of HupL is similar to that of R. capsulatus, B. japonicum, and A. vinelandii at amino acid levels of 63%, 65%, and 68%, respectively. Northern hybridization analysis showed that hupS and hupL were co-transcribed, and addition of fructose to the culture medium remarkably decreased the amount of mRNA transcribed from hupS and hupL.     

The structure and optical properties of GeO2-GeS2 glasses

Oxy-chalcogenide glasses with compositions of xGeO₂-(100 − x)GeS₂, where 0 ? x ? 100 mol%, have been prepared and studied in terms of their structures and optical properties. X-ray fluorescence spectroscopy shows that Ge:S ratio can deviate from GeS₂ by ∼10 at.%, depending critically upon the preparation conditions. Raman scattering spectroscopy suggests that stoichiometric GeO₂-GeS₂ glasses have a heterogeneous structure in the scale of 1-100 nm. The optical gaps are nearly constant at 3.0-3.5 eV for glasses with 0 ? x ? 80 mol% and abruptly increase to ∼6 eV in GeO₂. This dependence suggests that the optical gap is governed by GeS₂ clusters, which are isolated and/or percolated. Composition-deviated glasses appear as orange and brown, and these glasses seem to have more inhomogeneous structures.     

Photo-induced phenomena in sputtered GeO2 films

Macroscopic and microscopic changes in sputtered GeO₂ films induced by band-gap light from an ArF excimer laser have been studied. When irradiated at 1 atm, the film thickness increases, surface-roughness increases, refractive-index decreases, hygroscopic enhancements, and Ge-O-Ge distance increases. Irradiations in vacuum make these changes smaller or undetectable. These photo-induced changes are discussed from phenomenological and structural viewpoints, and compared with characteristics in GeO₂-SiO₂ and GeS₂ films.     

Study of the trapping of positive muons by extended defects in aluminum

PulsedSR spectra were measured with surface ⁺ in neutron irradiated aluminum as a function of specimen temperature above room temperature. It was found that the depolarization rate of ⁺ increases and the precession frequency decreases as the specimen temperature is raised. This fact was attributed to the trapping of ⁺ by radiation induced voids and suggests the importance of ⁺-surface interactions in the case of voids.     

Ultraviolet-induced erasable photochromism in bilayer metal oxide films

We demonstrate that the optical transmittance of bilayer samples consisting of pyrolytically coated amorphous Mg-Sn-O and metal oxide films such as In₂O₃ and SnO₂ decreases upon ultraviolet illumination, but can be recovered by annealing in air at ∼300 ^°C. Spectral, structural, and compositional studies suggest that this photochromic phenomenon is induced by photoelectronic excitation in the Mg-Sn-O film, electron injection into the metal oxide, which becomes negatively charged, and subsequent formation of metallic particles, which absorb and/or scatter visible light.