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  • Author or Editor: Y. Tanaka x
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Abstract  

A new α track method is proposed for the measurement of radon (222Rn) concentration in environmental levels. This involves collecting radon daughters on the surface of pilot lamp and detecting α-particles emitted from the nuclides (218Po and214Po) by a detector (LR 115). The detection sensitivity of this method is 6 times greater than that of the conventional α track method.

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Abstract  

Nickel sulfide (NiS) fire assay was used for the pre-concentration of Ir and Au in rock samples. The beads obtained after fire assay were irradiated directly with neutrons to determine Ir and Au. To suppress the reaction of 58Ni(n,p)58Co, the fire assay was carried out by using a small amount of Ni (0.0625 g) and the NiS bead samples were irradiated by neutrons with high Cd ratios. Analytical results of Ir and Au for rock samples were close to literature values, confirming that our procedure of INAA with pre-concentration can be applied to rock samples for the determination of ppb to sub-ppb level of Ir and Au.

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Abstract  

Sediments of the Kitajukkengawa River (Sumida-ku, Tokyo, Japan) were analyzed by activation analyses. Concentrations of 36 elements for each sample were determined by instrumental neutron activation analysis (INAA) and neutron induced prompt gamma-ray analysis (PGA). Based on the correlation matrix between the elements in vertical distribution, principal component analysis (PCA) was performed. The degree of chemical weathering of silicate minerals was highest in the middle layer of the Kitajukkengawa River sediment and that adsorbed amount of trace metals such as Cd and Cr was increased along with chemical weathering.

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Abstract  

Speciation and solubility of neptunium were studied using paper electrophoresis, ion exchange and ultrafiltration. Among these methods, the paper electrophoresis was found to be suitable for measuring speciation and solubility of neptunium of low concentration, if chemical species had opposite charge each other or dissolved species had a charge. Using paper electrophoresis, hydrolysis constants of NpO2OH0 and NpO 2 (OH) 2 and solubility product of NpO2 were obtained and ionic-strength dependence of speciation was observed.

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Abstract  

High resolution-type ICP-MS was applied to the analysis of 239Pu and 240Pu in soil samples. The detection limit of Pu was about 0.001 pg.ml-1 (ppt) in the sample solution or about 0.0005 pg in a total sample. This method was used to determine concentrations of Pu and its isotopic ratios in several soil samples collected from different areas in Japan. Concentrations of Pu in surface soils collected from forests were significantly higher than those in soils from agricultural fields. The 240Pu/239Pu atom ratios observed were usually 0.17-0.19, except for one very low ratio (0.037) found in the Nishiyama area (Nagasaki).

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Abstract  

The effect of atmospheric water vapor on the kinetic rate behavior of the thermal decomposition of copper(II) carbonate hydroxide, Cu2CO3(OH)2, was investigated by means of TG-DTA coupled with a programmable humidity controller. With increasing water vapor pressure p(H2O) from 0.8 to 10.6 kPa, a systematic reduction of the reaction temperature of the thermal decomposition was observed as the continuous trend from the previous works at the lower p(H2O). Through a comparative kinetic analysis of the reaction at different p(H2O), a catalytic action of the atmospheric water vapor on the nucleation process at the first half of the reaction was identified as the possible origin of the reduction of the reaction temperature.

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Abstract  

An experimental method is described for the synthesis of195mPt-radiolabeled cis-diammine (glycolato) platinum (II) (254-S). Ten mg of 95% enriched194Pt was irradiated for 75 h in the hydraulic conveyer of KUR at a thermal neutron flux of ca. 8.15×1013 n·cm–2·s–1, and the195mPt-radiolabeled 254-S was synthesized and purified using HPLC (column: Dichrosorb Diol, elution: 80% CH3CN). The chemical yield was approximately 45%, with chemical purity greater than 98.4%. The radionuclidic purity was nearly 100% and the specific activity, 7.2 MBq·mg–1 254-S.

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Abstract  

The literature indicates that the interaction of Tb3+ with DNA modified by the antitumour drug cis-diaminedichloroplatinum(II) (CDDP) results in substantial enhancement of the fluorescence of this cation, while no enhancement is observed in the case of DNA modified by irradiation with ionizing radiation. This study investigates the effect of Tb3+ on the survival of cultured mammalian cells treated with CDDP. HeLa cells were treated with a combination of195mPt-CDDP and TbCl3, and the relationship between lethal effect and the numbers of Tb and/or Pt atoms binding to DNA, RNA and proteins was examined. The Tb content in each fraction was determined using instrumental neutron activation analysis. It was found that the cytotoxic effect of CDDP was greatly enhanced by the presence of Tb ions (D0 of CDDP fell from 8.3 μM without Tb to 3.2 μM with 0.75 mM Tb), while no such effect was found in radiation-induced cell-killing. The number of Tb atoms bound to DNA molecules in a cell was calculated to be about 4.5·107, namely 1 per 1.400 nucleotides, under that situation.

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Abstract  

The lanthanides (REEs) in 142 fern leaves collected from 9 sampling sites in Japan were analyzed by instrumental neutron activation analysis. Between two REEs a strong positive correlation was found in the logarithmic scattering diagram with correlation and regression coefficients close to unity, suggesting neither selective accumulation by plants nor different availability from soil between the two elements. However, between Tb and the other REEs the relationship showed two lines with the same correlation coefficient. This suggested that there must be a difference in the availability of REEs or in their absorption characteristics by plants. Further analysis revealed that the splitting was due to some difference in the environmental factors where the fern grew. However, the amount of REE in the soil collected together with the corresponding fern did not reflect the REE concentration in the fern leaves.

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Abstract  

Positron annihilation lifetimes were measured for several polymers in the atmosphere of high pressure CO2 gas. At low CO2 pressured both 3 andI 3 decreased due to the Langmuir-type sorption, and at higher pressures their values recovered because the Henry-type sorption takes over. The amount of sorbed CO2 and dilation of the bulk volume were measured simultaneously, and the free volume fraction was determined at each CO2 pressure. The free volume fraction became smaller (for polyimide and polycarbonate) or slightly larger (for polyethylene) with the progress of sorption. However, the size of the o-Ps hole estimated from the 3 value increased regardless of the change of the free volume fraction. It appears that o-Ps is selectively looking at larger holes or expanding the holes in which it is accommodated. For polycarbonate, which remains to be glassy even at the largest CO2 sorption attained in the experiment, the o-Ps hole size became larger than that before sorption. This implies that, even if the polymer is glassy as bulk, the sorption site is strongly prone to molecular displacement by the pressure of the penetrating Ps. Cautious consideration is evoked about directly correlating the o-Ps lifetime and intensity with the free volume in general.

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