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Abstract  

The size distribution of free-volume (<~0.1 nm3) of ethylene-vinyl alcohol copolymer with various crystalline degrees was estimated by positronium lifetime measurement. With increasing degree of crystallinity, the size distribution significantly narrowed and the intensity of positronium decreased. This indicates that the inhomogeneity reduces with the increase of the degree of crystallinity. It is found that the free-volume fraction estimated is reflected by the fraction of the amorphous region.

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Abstract  

TG and DTA experiments were performed to investigate the biomass tar combustion behavior in coexistence of dolomite and mayenite at two different heating rates as 5 and 15°C min−1. Different reaction kinetic mechanisms with the classical Arrhenius model were used to treat TG data, and showed that the first-order combustion model fitted the data well. Three stages combustion model was proposed and applied for the calculation of kinetics parameters successfully. The starting temperature of high temperature combustion stage moved up near 100°C because of the coexistence catalysts, and the combustion amount of biomass of the stage also improved nearly 10 mass%. By calculation a uniform trend of decreasing activation energies was observed with the addition of dolomite and mayenite, and also greatly improved the amount and speed of tar combustion process.

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Abstract  

Dietary intakes of radiocesium and non-radioactive cesium in Japanese were estimated using a market basket study and found to be 61 mBq and 9.1 ng per person per day, respectively. Food categories having higher Cs contents (per g-fresh) were found to be as follows: mushrooms 35.9 ng; nuts and seeds 33.6 ng; meats 26.8 ng; fishes and shellfishes 21.6 ng; potatoes 19.2 ng; seaweeds 10.2 ng; and milk and milk products 7.19 ng. For137Cs, higher contents (per kg-fresh) were as follows: mushrooms 1.7 Bq; nuts and seeds 0.23 Bq; fishes and shellfishes 0.16 Bq; meats 0.13 Bq; potatoes 0.11 Bq; seaweeds 0.092 Bq; and milk and milk products 0.089 Bq. Distributions of stable cesium in the 18 food categories were similar to those of radiocesium.

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Abstract  

To estimate fast neutron fluence released by the JCO criticality accident in Tokai-mura, 54Mn, which is produced by the 54Fe(n,p)54Mn reaction, was determined in soil samples by ultra low background g-ray spectrometry after radiochemical separation. Activities of 54Mn, using 30-200 g soil samples were detected in soil samples from 13 points in all directions within a 20 m zone from the precipitation vessel we have used. The levels of 54Mn ranged from 0.015 to 2.12 mBq/g soil. By using these data and MCNP, the fast neutron fluences were estimated.

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Abstract  

To determine the levels of210Pb and210Po in human tissues of people in Japan, various tissue samples were obtained at autopsy from the cadavers of 22 oncologic cases, mainly in Niigata Prefecture in northern Japan, from 1986 to 1988.Wet ashing, followed by electrochemical deposition and alpha spectrometry were used to separate and determine the210Pb and210Po present. Among the tissues analyzed, the highest concentrations of210Pb and210Po were observed in bone (sternum), liver, and kidneys. The total body burden of210Pb and210Po was found to be approximately 427 pCi and 514 pCi, respectively. This estimated210Po value did not differ significantly from values found in populations in the U.S.A. and European countries.

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Abstract  

Chemical leaching experiments of237Np in the sediments from the Esk Estuary and the Ribble Estuary in the Irish Sea, U. K., have been carried out, in comparison with those of239, 240Pu and241Am, to understand the geochemical associations of these long-lived radionuclides with sediment. Experimental results show that partitioning behavior of237Np is obviously different from those of239, 240Pu and241Am.

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Abstract  

210Pb and210Po in human hair have been measured to serve as an aid in order to estimate the dietary intake and body burden of these radionuclides of Japanese. The210Po concentrations found in 83 hair samples were ranging from 4.0 to 59.3 mBq/g with a mean (median) value of 18.2±12.2 (14.9) mBq/g as compared to the210Pb concentrations from 0.7 to 6.5 mBq/g with a mean (median) value of 2.3±1.1 (2.0) mBq/g. The210Po/210Pb activity ratios (mean: 8.7±5.1, median: 7.1) were surprisingly higher compared with the available literature value of about 2. The high concentration of210Po in human hair of Japanese may be due to the ingestion of animal protein mainly in the form of seafood.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Y. Kawabata
,
M. Yamamoto
,
V. Aparin
,
S. Ko
,
K. Shiraishi
,
M. Nagai
, and
Y. Katayama

Summary  

Water and phosphorous fertilizer samples from Karakalpakstan in the Republic of Uzbekistan were analyzed by inductively coupled plasma mass spectrometry, (ICP-MS) to demonstrate the water quality in drinking water, rivers and canals. Uranium concentrations exceeded the WHO (2004) guideline levels for drinking water at some sampling points. Since uranium can also have a toxic effect on kidneys, the effect of uranium from drinking water on people in these areas is significant. One of the main pollutant sources is the phosphate fertilizer leached from agriculture land.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Y. Kawabata
,
V. Aparin
,
M. Nagai
,
M. Yamamoto
,
K. Shiraishi
, and
Y. Katayama

Abstract  

Uranium and thorium concentrations in water and in soil from Kazakhstan have been investigated. In some sampling points the uranium concentrations of drinking water, exceeded the WHO guideline level for drinking water. Thus, the human effect of uranium exposure from drinking water in these areas is significant. However, soil samples were the same as in the Nature. Irrigation systems in these areas would be easy for water carried in the drains mix with groundwater. The results here suggest that the uranium passes into the groundwater through the agriculture land by the above mechanism.

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Abstract  

36Cl in soil samples from the Semipalatinsk Nuclear Test Site (former USSR) was measured at Kyushu University Tandem Laboratory (KUTL) by accelerator mass spectrometry (AMS) coupled with projectile X-ray detection (PXD) technique. The separation of competing 36S and 36Cl atomic isobars, was satisfactory by PXD technique. Measured 36Cl/Cl atom ratio was (5.0±0.6).10–10 and an average activity of 36Cl was calculated as (2.0±0.2) mBq/g, which is in a good agreement with that obtained by liquid scintillation counting (LSC) method previously. Currently developed AMS system at the Kyushu University can be applied for routine 36Cl analysis at 36Cl/Cl = 10–11 atom ratio level.

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