Molecular dynamics simulation of 7, 8-dihydro-8-oxoguanine DNA.

To elucidate the effect of guanine lesion produced by the oxidative damage on DNA, 1 nanosecond molecular dynamics simulations of native and oxidized DNA were performed. The target DNA molecules are dodecamer duplex d(CGCGAATTCGCG)(2) and its derivative duplex d(C(1)G(2)C(3)(8-oxoG)(4)A(5)A(6)T(7)T(8)C(9)G(10)C(11)G(12).d(C(13)G(14)C(15)G(16)A(17)A(18)T(19)T(20)C(21)G(22)C(23)G(24), which has one oxidized guanine, 7, 8-dihydro-8-oxoguanine (8-oxoG), at the fourth position.

Grazing-incidence Monk-Gillieson monochromator based on surface normal rotation of a varied-line-spacing grating.

A geometric theory of a grazing-incidence varied-line-spacing plane-grating monochromator system whose scanning is made by a simple grating rotation about the grating normal has been developed for designing Monk-Gillieson monochromators capable of covering an energy range of 0.6-2.5 keV.

Positional effect of cell inactivation on root gravitropism using heavy-ion microbeams.

When primary root apical tissues of Arabidopsis thaliana were irradiated by heavy-ion microbeams with 120 microm diameter, strong inhibition of root elongation and curvature were observed at the root tip. Irradiation of the cells that become the lower part of the root cap after gravistimulation showed strong inhibition of root curvature, whereas irradiation of the cells that become the upper part of the root cap after gravistimulation did not show severe damage in either root curvature or root growth. Further analysis using smaller area microbeams with 40 microm diameter indicated that the greatest inhibition of curvature occurred at the root tip and the next greatest inhibition occurred in the cells in the lower part of the root cap.

Effects of ionic valency of interacting metal elements in ion uptake by carrot (Daucas carota cv. U.S. harumakigosun).

Interaction of elements in the course of element uptake by carrot (Daucas carota cv. U.S.

Prediction of orbital ordering in single-layered ruthenates.

The key role of the orbital degree of freedom to understanding the magnetic properties of layered ruthenates is discussed based on the 3-orbital Hubbard model coupled to lattice distortions, using numerical and mean-field techniques. In the G-type antiferromagnetic phase of Ca(2)RuO(4), recent x-ray experiments reported 0.5 holes/site in the d(xy) orbital, while d(yz) and d(zx) orbitals contain 1.

Dissolution rate of hen egg-white lysozyme crystal under microgravity.

Protein crystallization under micro gravity has been already tried many times in the United States and other countries, and it is reported that about 20% of proteins were better crystallized under microgravity than on earth. This verified that microgravity is sometimes effective in protein crystallization. However, if these procedures continued to be carried out without clarifying which processes are effective, improved development of protein crystallization cannot be expected.

Analysis of a uranium solution for evaluating the total number of fissions in the JCO criticality accident in Tokai-mura.

The uranium solution in the precipitation tank in the JCO's uranium conversion facility was analyzed in order to evaluate the total number of fissions in the criticality accident. Two analytical groups at JAERI performed chemical analyses independently in order to check the validity of the results: the concentration of the fission products (95Zr, 99Mo, 103Ru, 131I, 140Ba, etc), uranium, boron and impurity elements in the solution. The analytical results obtained by the two groups were almost in agreement within the analytical error.

Summary of the JCO criticality accident in Tokai-mura and a dose assessment.

A criticality accident occurred on September 30, 1999, in a conversion test facility at the JCO Tokai site. The accident was triggered by pouring an 18.8% enriched uranyl nitrate solution into a precipitation vessel beyond the critical mass.

Characterization of RecA424 and RecA670 proteins from Deinococcus radiodurans.

RecA protein is considered to be the most important participant in the radiation resistance of Deinococcus radiodurans. However, it is still unclear how RecA contributes to the resistance. In this study, we identified a new recA mutation (recA424) in the DNA-repair deficient mutant strain KI696, the phenotype of which is remarkably different from mutant strain rec30 carrying recA670.

Crystallization of a large single crystal of a B-DNA decamer for a neutron diffraction experiment by the phase-diagram technique.

Crystallization of a large single crystal of a B-DNA decamer, d(CCATTAATGG), for a neutron-diffraction experiment has been accomplished by an analysis of its solubility phase diagram and a large single crystal was successfully crystallized at around the minimum solubility point of the oligonucleotide: 30%(v/v) MPD, 100 mM MgCl(2) pD 6.6 using 0.4 ml D(2)O solutions of the DNA (sample concentration 1.

Plasma equilibrium and confinement in a tokamak with nearly zero central current density in JT-60U.

A high confinement equilibrium with nearly zero toroidal current in the central region (a "current hole") has been observed for the first time to persist stably for several seconds in the JT-60U tokamak. This observation indicates the possibility of stable tokamak operation without central toroidal current; the central current has previously been believed to be necessary in tokamaks. The radius of the current hole extended up to 40% of the plasma minor radius.

Numerical study of laser wake field generated by two colliding laser beams.

The laser wake field generated by two colliding laser beams has been studied numerically. The wake field amplitude is enhanced by a counterpropagating long pulse laser, which has an appropriate frequency difference, and becomes an order of magnitude larger than that of the standard wake field. The field amplitude increases in proportion to the pumping laser intensities until it saturates under the wave breaking limit.

The LexA protein from Deinococcus radiodurans is not involved in RecA induction following gamma irradiation.

The involvement of LexA in induction of RecA was investigated in Deinococcus radiodurans. As in the wild-type strain, an increase in RecA protein synthesis following gamma irradiation was detected in a lexA disruptant, indicating that LexA is not involved in the induction of RecA in D. radiodurans.

X-ray absorption study of molten yttrium trihalides.

The local structure and structural changes in molten YCl3-LiCl-KCl and molten YBr3-LiBr systems have been investigated by using a high-temperature extended X-ray absorption fine structure (EXAFS) technique. The behaviour of octahedral coordination of the halide ion (Cl(-) and Br(-)) around the Y(3+) ion has been studied by EXAFS of the Y K-absorption edge. The nearest Y(3+)-Cl(-) and Y(3+)-Br(-) distances and coordination numbers of halide ions around the Y(3+) ion do not change by mixing with the alkali halides.

Relations between tooth enamel dose and organ doses for electron spin resonance dosimetry against external photon exposure.

An analysis of doses to tooth enamel and to organs was carried out to develop a method that can predict the organ doses and the effective dose by electron spin resonance (ESR) dosimetry using tooth samples for external photon exposure. Absorbed dose to tooth enamel and organ doses were obtained by Monte Carlo calculations using the EGS4 code in combination with a mathematical human model with a newly defined teeth part. The calculations gave quantitative relations between tooth enamel dose and organ doses for some cases of external photon exposure.

An experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy.

A radiation streaming experiment has been carried out at the Takasaki Ion Accelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicability of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerator operating in the intermediate energy region.

Uncertainties in estimated body burdens of caesium-137 by whole-body counting.

It is very important to evaluate the uncertainties in individual monitoring for internal exposure of workers. The uncertainties in estimated body burdens of 137Cs with the JAERI whole-body counter were investigated using Monte Carlo simulation and measurements. It was found that the uncertainties of estimated body burdens with the whole-body counter are strongly dependent on various sources of uncertainty, such as radioactivity distribution within the body and counting statistics and that the 137Cs body burden assessed from the result of the whole-body count can be within +/- 60% in error.

A new method for determining HT deposition velocity and dependence of the velocity on environmental factors.

A new method was developed to determine HT deposition velocity and to investigate how environmental factors affect the deposition processes including the diffusion into soil and the biochemical conversion by microorganisms to HTO in soil. This method, using a chamber and two tritium samplers, enables determination of the HT deposition velocity in situ without a large scale experiment and an additional tritium source. The main problem concerning the use of a flow-through method is the possible effect of flow rate on flux measurement.

Evaluation of internal and external doses from 11C produced in the air in high energy proton accelerator tunnels.

Air has been irradiated with high energy protons at the 12 GeV proton synchrotron to obtain the following parameters essential for the internal dose evaluation from airborne 11C produced through nuclear spallation reactions: the abundance of gaseous and particulate 11C, chemical forms, and particle size distribution. It was found that more than 98% of 11C is present as gas and the rest is aerosol. The gaseous components were only 11CO and 11CO2, and their proportions were approximately 80% and 20%, respectively.

External doses in the environment from the Tokai-mura criticality accident.

On 30 September 1999, a criticality accident occurred at a uranium processing plant operated by JCO in Tokai-mura, Japan and the criticality remained for about 20 h. Almost all doses to the neighbouring residents were brought by neutrons and gamma rays emitted from the facility rather than fission products released to the environment. External doses in the environment were evaluated using radiation monitoring data and radiation transport calculation.

Deposition of tritiated water vapour to water surface in an outdoor field.

Deposition of tritiated water vapour in the atmosphere to a water surface was studied in an outdoor field, where elevated concentrations of tritiated water vapour existed in the atmosphere over twelve days. Exchange velocities of tritiated water vapour between air and water were evaluated from tritium concentrations in air and water obtained in the field experiment. It was found that the average of outdoor exchange velocities was about three times greater than that observed in a nuclear reactor room previously.

Effect of the space environment on the induction of DNA-repair related proteins and recovery from radiation damage.

Recovery of bacterial cells from radiation damage and the effects of microgravity were examined in an STS-79 Shuttle/Mir Mission-4 experiment using the extremely radioresistant bacterium Deinococcus radiodurans. The cells were irradiated with gamma rays before the space flight and incubated on board the Space-Shuttle. The survival of the wild type cells incubated in space increased compared with the ground controls, suggesting that the recovery of this bacterium from radiation damage was enhanced under microgravity.

Soft x-ray absorption spectra of ilmenite family.

We have carried out soft x-ray absorption spectroscopy to study the electronic structure of ilmenite family, such as MnTiO3, FeTiO3, and CoTiO3 at the soft x-ray beamline, BL23SU, at the SPring-8. The Ti and M L2,3 absorption spectra of MTiO3 (M=Mn, Fe, and Co) show spectra of Ti4+ and M2+ electron configurations, respectively. Except the Fe L2,3 spectrum, those spectra were understood within the O(h) symmetry around the transition metal ions.

Structural studies of lanthanide (III) complexes with oxydiacetic acid and iminodiacetic acid in aqueous solution by EXAFS.

The local structure of the trivalent lanthanide (Ln(III)) complexes with oxydiacetic acid (ODA) and iminodiacetic acid (IDA) in aqueous solution was investigated by EXAFS spectroscopy. The coordination number and the bond distance were obtained by the detailed EXAFS analysis. The coordination number of Ln(III) in both the Ln-ODA and -IDA systems decreases from nine for lighter Ln(III) to eight for heavier Ln(III).

EXAFS studies of americium (III)-benzimidazole complex in ethanol.

The local structures of Am, Nd and Er-Benzimidazole (Biz) in solution were determined by EXAFS. The BIZ molecule coordinated to Am and Nd through two nitrogen atoms in a bidentate fashion. Two nitrogen atoms of BIZ ligated to Am and Nd with the bond distances R(Am-n) N=2.