Core-excited states in the doubly magic 68Ni and its neighbor 69Cu.

In deep-inelastic collisions of 8 MeV/nucleon 70Zn projectiles with 198Pt, we have found an 8(+) isomer with T(1/2) = 23(1) ns at 4208 keV in 68Ni; the nug(9/2) E2 effective charge was determined to be 1. 5(1)e. In 69Cu, a 19/2(-) isomer with T(1/2) = 22(1) ns at 3691 keV was identified and its decay data were calculated quite accurately by a parameter-free shell model calculation using empirical input parameters.

Mechanism for negative poisson ratios over the alpha- beta transition of cristobalite, SiO2: A molecular-dynamics study.

The adiabatic elastic constants ( C(ij)) of cristobalite have been evaluated successfully over the temperature range of 300-1800 K using the molecular-dynamics method with a fluctuation formula. Cristobalite shows a negative Poisson ratio over this temperature range. However, the mechanisms differ between the alpha and beta phases.

Development of analytical techniques for ultra trace amounts of nuclear materials in environmental samples using ICP-MS for safeguards.

The authors have begun to develop analytical techniques for ultra trace amounts of nuclear materials and to prepare a clean chemistry laboratory for environmental sample analyses. The analytical techniques include bulk and particle analyses. For the bulk analysis, concentrations and isotopic ratios of U and/or Pu are determined by inductively-coupled plasma mass spectrometry (ICP-MS) and thermal ionization mass spectrometry (TIMS).

The resonance Raman effect of uranyl chloride in dimethyl sulfoxide.

A study was carried out of the resonance Raman scattering spectra of uranyl chloride (UO2Cl2) in dimethyl sulfoxide ((CH3)2SO) (DMSO) under laser excitation of the UO2(2+) ion in resonance with the 1sigma(g)+ --> 1phi(g) Laport-forbidden f-f electronic transitions span from 530 to 450 nm by using ten output lines of the argon-ion laser at room temperature. The resonance Raman excitation profile of the totally symmetric stretching vibrational mode of uranyl observed at 832 cm(-1) is presented and analyzed in terms of transform theory within the non-Condon model to give relatively good agreement with experimental results. The disagreement between the experimental data and the calculated resonance Raman excitation profile, at the long-wave part of the the 1sigma(g)+ --> 1phi(g) electronic transitions, may be referred to interference between the weak scattering from the neighboring forbidden electronic states (1delta(g)) and strong preresonance scattering from allowed electronic states at higher levels.

Properties of a YAP powder scintillator as alpha-ray detector.

A YAP scintillator (YAlO3: Ce crystal) for alpha counting has been produced in powder form and this paper describes its performance characteristics. By measuring pulse-height and rise-time distributions, it was found that the YAP powder, as a fast detector for alpha rays, could clearly distinguish alpha events from beta and gamma events. In addition, the YAP powder was used in a phoswich detector combined with a YAG (Y3Al5O12: Ce) crystal for beta and gamma detection.

Prompt gamma-ray analysis using cold and thermal guided neutron beams at JAERI.

A highly sensitive neutron-induced prompt gamma-ray analysis (PGA) system, usable at both cold and thermal neutron beam guides of JRR-3M, has been constructed. The system was designed to achieve the lowest gamma-ray background by using lithium fluoride tiles as neutron shielding, by placing the samples in a He atmosphere and by using a Ge-bismuth germanate detector system for Compton suppression. The gamma-ray spectrometer can acquire three modes of spectra simultaneously: single, Compton suppression, and pair modes.

An external ion microbeam for studies of biological samples.

A new external ion-beam system was developed and combined with a light ion-microbeam system in JAERI Takasaki. The system is designed for micro-particle-induced X-ray emission analysis of biological samples in air environment with 1 micron spatial resolution. One of the most serious problems in keeping such a high spatial resolution is multiple scattering in a beam exit window.

A first-order liquid-liquid phase transition in phosphorus.

First-order structural phase transitions are common in crystalline solids, whereas first-order liquid-liquid phase transitions (that is, transitions between two distinct liquid forms with different density and entropy) are exceedingly rare in pure substances. But recent theoretical and experimental studies have shown evidence for such a transition in several materials, including supercooled water and liquid carbon. Here we report an in situ X-ray diffraction observation of a liquid-liquid transition in phosphorus, involving an abrupt, pressure-induced structural change between two distinct liquid forms.

Evolutionally conserved plant homologue of the Bax inhibitor-1 (BI-1) gene capable of suppressing Bax-induced cell death in yeast(1).

The plant homologue of Bax Inhibitor-1, a gene described to suppress the cell death induced by Bax gene expression in yeast, was isolated from Oryza sativa L. (rice) and Arabidopsis. The amino acid sequence of the predicted protein was well conserved in both animal and plant (45% in amino acids) and contained six or seven membrane-spanning segments.

Molecular analysis of the Deinococcus radiodurans recA locus and identification of a mutation site in a DNA repair-deficient mutant, rec30.

Deinococcus radiodurans strain rec30, which is a DNA damage repair-deficient mutant, has been estimated to be defective in the deinococcal recA gene. To identify the mutation site of strain rec30 and obtain information about the region flanking the gene, a 4.4-kb fragment carrying the wild-type recA gene was sequenced.

Identification and disruption analysis of the recN gene in the extremely radioresistant bacterium Deinococcus radiodurans.

We isolated a radiosensitive mutant strain, KR4128, from a wild-type strain of Deinococcus radiodurans, which is known as a extremely radioresistant bacterium. The gene that restore the defect of the mutant in DNA repair was cloned, and it turned out to be the homolog of the recN gene of Escherichia coli. The recN gene encoded a protein of 58 kDa, and, in its N-terminal region, a potential ATP binding domain was conserved as expected for a prokaryotic RecN protein.

Molecular cloning of Arabidopsis photolyase gene (PHR1) and characterization of its promoter region.

Photolyase is an enzyme that repairs ultraviolet (UV)-damaged DNA by photoreactivation. In higher plants, accumulation of photolyase (PHR1) mRNA is induced by either UV or visible light. In order to know the molecular mechanism by which PHR1 gene expression is induced by light, we have determined the genomic structure and the 5'-flanking sequence of the Arabidopsis PHR1 gene.

Nucleotide sequence of the GLABROUS1 gene of Arabidopsis thaliana ecotype Columbia.

The GLABROUS1 (GL1) gene from Arabidopsis thaliana ecotype Columbia was isolated and sequenced. Comparison of the nucleotide sequence with that of the gl1-2allele revealed that two sites were changed in gl1-2. One was a 14-bp deletion in exon 3, which seemed most likely to be the cause of the mutated phenotype.

Neutrons expand the field of structural biology.

Neutron protein crystallography aids the identification of all the hydrogen atoms in biological macromolecules and has helped to establish hydration patterns in proteins. Recent technical innovations, such as the development of the neutron imaging plate, have made it possible to shorten the prohibitively long amount of time required to collect a full diffraction data set. These instrumental advances have been applied to Laue diffractometry, as well as to more conventional data collection techniques, such as those using monochromatized neutron beams.

Single- and double-strand breaks in solid pBR322 DNA induced by ultrasoft X-rays at photon energies of 388, 435 and 573 eV.

We measured strand breaks of pBR322 plasmid DNA irradiated with ultrasoft X-rays using monochromatic synchrotron radiation as a light source. Three photon energies, 388, 435 and 573 eV, a value below and above the nitrogen K-edge and above the oxygen K-edge, respectively, were chosen for the irradiation experiments as they have an equivalent photon transmittance of the sample. Irradiated DNA was analyzed by agarose gel electrophoresis and the numbers of single- and double-strand breaks (ssb and dsb) were determined by measuring the band intensity on the gel after ethidium bromide staining.

Cesium-137 and mercury contamination in lake sediments.

The contribution of fluvial discharge and global fallout of 137Cs and mercury to sedimentation fluxes in Lake Shinji and Lake Nakaumi, Japan, was studied. The fluvial flux through soil erosion accounted for 11 to 27% of accumulated 137Cs in the sediments in the 1950's and 1960's, which were the periods of the most extensive atmospheric input, and for 90 to 100% in the 1990's. The vertical profiles of mercury concentrations in the lake sediments studied showed a maximum between 1959 and 1963, which was originated mostly from the extensive use of mercury-agrochemicals in paddyfields of the watershed in the past.

Production of radioactive endovascular stents by implantation of 133Xe ions.

A coronary stent was made radioactive by implantation of 133Xe ions for the purpose of suppressing the renarrowing of the part of blood vessel in which the stent is implanted. Electrons of relatively low energies emitted in the decay of 133Xe may give an antiproliferative effect of ionizing radiation to the intimal cells within a limited range of 1 mm. A 133Xe+ beam accelerated at 40 or 60 keV was directed to several stainless steel stents mounted on a target-holder table that could revolve and move up and down to distribute the 133Xe+ ions within a stent as well as among the stents.

Molecular analysis of carbon ion-induced mutations in Arabidopsis thaliana.

In order to elucidate the characteristics of the mutations induced by ion particles at the molecular level in plants, mutated loci in carbon ion-induced mutants of Arabidopsis were investigated by PCR and Southern blot analyses. In the present study, two lines of gl1 mutant and two lines of tt4 mutant were isolated after carbon ion-irradiation. Out of four mutants, one had a deletion, other two contained rearrangements, and one had a point-like mutation.

Protein adsorption characteristics of a sulfonic-acid-group-containing nonwoven fabric.

A sulfonic acid (SO3H)-group-containing nonwoven fabric was prepared by radiation-induced graft polymerizaton of an epoxy-group-containing monomer, glycidyl methacrylate, onto a nonwoven fabric and subsequent sulfonation. The nonwoven fabric containing SO3H groups at different densities was equilibrated with lysozyme in a buffer (pH 6.0).

Calculation of the effective dose and its variation from environmental gamma ray sources.

Effective dose, an indicator of the stochastic effect of radiation, has been widely used in dose evaluation in the environment. Though conversion factors have been used to obtain E from the air kerma or air absorbed dose, the variation of the conversion factors due to the change of exposure conditions has not been sufficiently investigated. This report documents an investigation of the variation of the effective dose per air kerma for environmental gamma rays depending on the exposure conditions using anthropomorphic phantoms and Monte Carlo calculations, taking into account the precise angular and energy distributions of the environmental gamma rays incident on the human body.

Time-dependent chemical compositions of 13N and 15O induced in air by the operation of a high energy electron accelerator.

Time-dependent chemical compositions for 13N and 15O induced in the air atmosphere of a high energy electron accelerator room have been studied using a computer simulation method. A radiation chemistry model was developed to describe the chemical reactions of 13N and 15O species with the air molecules and their radiolytic products. By assuming several chemical forms of 13N and 15O generated by the (gamma, n) reaction, the variations of the concentrations of 13N and 15O species were simulated under a radiation field.

Correlation between Extraction Equilibrium of Uranium(VI) and Density of CO(2) Medium in a HNO(3)/Supercritical CO(2)-Tributyl Phosphate System.

The extraction equilibrium of U(VI) between a nitric acid solution and a supercritical CO(2) phase containing tributyl phosphate (TBP) is formulated taking into account that (i) a distribution ratio of a metal extracted is a function of a distribution constant of each component involved in the extraction reaction, (ii) the distribution constant is defined as a ratio of solubilities of the component in both phases, and (iii) the solubility in the CO(2) phase is correlated with density of CO(2). A simple linear relationship between the distribution ratio, D(U), of U(VI) and density, ρ, of CO(2) is derived; log D(U) = a log ρ + A + B, in which a is a proportional constant implying the solvation characteristic of the solute in supercritical CO(2), A is a pressure-independent constant, and B is a variable determined by the distribution equilibrium of HNO(3). The equation derived was verified experimentally by the measurement of the distribution ratio of U(VI) and HNO(3) under various conditions of pressure and temperature.

The postspinel phase boundary in Mg2SiO4 determined by in situ X-ray diffraction.

The phase boundary between spinel (gamma phase) and MgSiO3 perovskite + MgO periclase in Mg2SiO4 was determined by in situ x-ray measurements by a combination of the synchrotron radiation source (SPring-8) and a large multianvil high-pressure apparatus. The boundary was determined at temperatures between 1400 degrees to 1800 degreesC, demonstrating that the postspinel phase boundary has a negative Clapeyron slope as estimated by quench experiments and thermodynamic analyses. The boundary was located at 21.

The Deinococcus radiodurans uvr A gene: identification of mutation sites in two mitomycin-sensitive strains and the first discovery of insertion sequence element from deinobacteria.

Deinococcus radiodurans (Dr) possesses a prominent ability to repair the DNA injury induced by various DNA-damaging agents including mitomycin C (MC), ultraviolet light (UV) and ionizing radiation. DNA damage resistance was restored in MC sensitive (MC(S)) mutants 2621 and 3021 by transforming with DNAs of four cosmid clones derived from the gene library of strain KD8301, which showed wild type (wt) phenotype to DNA-damaging agents. Gene affected by mutation (mtcA or mtcB) in both mutants was cloned and its nucleotide (nt) sequence was determined.

Neutron Laue diffractometry with an imaging plate provides an effective data collection regime for neutron protein crystallography.

Neutron quasi-Laue diffraction data (2 A resolution) from tetragonal hen egg-white lysozyme were collected in ten days with neutron imaging plates. The data processing Laue software, LAUEGEN, developed for X-ray Laue diffractometry, was adapted for neutron diffractometry with a cylindrical detector. The data analysis software, X-PLOR, was modified and used for the refinement of hydrogen atoms, and the positions of 960 hydrogen atoms in the protein and 157 bound water molecules, were determined.