Sadashi Sawamura

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To determine quantities for radiation protection against high-energy electrons, such as those from LINAC, the organ dose equivalents and equivalent doses for the human body were calculated using EGS-4 Monte Carlo simulation code and an MIRD-5 mathematical human phantom. Conversion factors for the incident fluence to the organ dose equivalent, to the(More)
This study was performed to confirm the radiation-chemical properties of the 2-nitroimidazole derivative doranidazole, (+/-)-(2RS,3SR)-3-[(2-nitroimdazol-1-yl)-methoxy]butane-1,2,4-triol [CAS 137339-64-1], PR-350, which was synthesized as a hypoxic cell radiosensitizer with low toxicity. Radiation-chemical experiments using doranidazole showed that (1)(More)
Continuous (222)Rn monitoring in soil gas since November 22, 2004 has revealed variability in activity concentration with time in the semi-natural woods on the campus of Hokkaido University in Sapporo, Japan. Among various factors affecting soil radon levels and variability, temperature was found to be dominant during three seasons when activity(More)
Vertical profiles of environmental radionuclides (40K, 226Ra, 210Pb and 137Cs) were investigated in several temperate forest soils in Germany to estimate heterogeneity of the soil horizon of interest. Absolute values of the activity concentrations of these nuclides varied to a large extent depending on the properties of individual forests as well as local(More)
An N2O-saturated aqueous solution containing 2'-dG and the spin trap agent PBN was examined by ESR and HPLC-ECD methods after X irradiation. ESR examination showed that the ESR spectrum obtained consisted of signals due to the PBN-OH and PBN-H adducts. The signal intensity of PBN-H adducts was larger in the presence of 2'-dG than in the absence of 2'dG,(More)
The application of superheated emulsion as a neutron spectrometer is described by varying the operating temperature and the ambient pressure of the emulsion. For the calibration of the detector, a relationship was established between the degree of metastability (ss) of superheated emulsion and the threshold neutron energy. The sensitivity and the integral(More)
Several factors controlling the soil radon level in the present site were found to be changing air-filled porosity caused by fluctuations in moisture content, differences between the atmospheric and soil temperatures as well as volumetric (226)Ra content of the soil. The radon activity increased significantly in early October, especially at point 1,(More)
Soil radon was measured from late October 2000 to January 2001 at three test sites on the campus of Hokkaido University in Sapporo, Japan. Factors affecting radon concentrations were investigated with relation to meteorological data, as well as soil 226Ra content, mineral composition, water content, and pH, Eh and conductivity. Soil radon varied with time(More)