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Abstract  

This paper gives the average ingestion levels of137Cs, released during the Chernobyl accident, for three population groups living in different regions of Italy. The ingestions were determined experimentally by measuring reconstructed total diets that were collected in the three areas.A comparison between this data and the ingestion levels, estimated by using the137Cs concentration levels measured in single food products and the national food consumption data, shows that the last method over-estimates the ingestion.Finally, it is shown that the ingestion levels of137Cs, as determined by measuring the reconstructed total diets, the internal body burden as measured directly by whole body counting, and urinary excretion are consistant.

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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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In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.

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A method is proposed by which the significance of the differences between trace element concentrations of sample and control can be estimated without detailed knowledge of the distribution in the total population. Both sample and control are cut in half and the trace element concentrations of all four pieces are determined. The concentration values of the two halves of each sample are compared with each other and so are the concentration values of the two samples. This cross-comparison is essentially the application of Student's t-test to the smallest possible number of data. The calculation is reduced to a simple formula, and tables of confidence limits are not needed. The implications of lack of general background knowledge are discussed. Since it cannot always be known whether a certain trace element follows a normal or log-normal distribution pattern, or whether simultaneously determined concentrations of several trace elements are correlated with each other, the most cautious estimate of the significance is recommended.

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The forensic activation analyst must often evaluate his own results as they relate to certain legal or moral situations, since investigative officers, and courts of law are not usually competent to make judgements of the validity or meaning of scientific data. In providing scientific evidence in court, two criteria for criminal identification must be met: (1) suspect's sample should be similar to sample found at the scene of the crime, (2) samples relared to other people in the same statistical population should not generally match that found at the crime site. When two or more specimens are submitted for comparison by NAA they will usually fall into one of three classes: (a) materials about which we have partial or inconclusive data, (c) materials with an excellent analytical data background. Ideally all cases would fall in category c; in practice, very few. Some examples of cases and/or situations that fall into these three categories in both individual and corporate investigations are given.

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Data are presented for210Po levels in edible parts of marine species significant in the diet of the Argentine population. The sample collection sites were situated between 35° and 45° S in the Atlantic Ocean. The specific activities obtained, expressed per wet veight and with a 95% confidence level, ranged between 31.3±9.1 mBq kg–1 for pollack (Genypterus blacodes) and 1790±280 mBq kg–1 for squid (Illex argentinus). Hake (Merluccius hubbsi) followed by squid are the major contributors to the dose. The annual committed effective doses were 0.7 mSv and 0.6 mSv and the effective collective doses were 24 man·Sv and 20 man·Sv, respectively, for these species. For the remainder, because of both their low consumption rates and low specific activities, the corresponding doses were negligible compared with the former.

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Uranium (U) and thorium (Th) isotopes and their several radioactive descendants found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. Phosphate rocks are really rich natural sources of uranium and thorium among the other minerals forming the earth's crust. U and Th concentrations in some Egyptian phosphate samples were determined using a nuclear track registration methodology and -ray spectroscopy. The resulting latent tracks from all -decaying isotopes in both U and Th series were recorded in plastic detectors. A uniquely sensitive polycarbonate CR-39 nuclear detector was used. Results showed that the U and Th concentration in the samples studied range from about 4.0 up to 35.0 ppm and from 11.0 to 124.0 ppm, respectively. Results are discussed within the frame work of track formation methodology in plastic and -ray spectroscopic analysis.

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Abstract  

EAEN (Advanced School of Nuclear Energy, 2010) is an annual school that consists of a week of activities in the area of Nuclear Physics, Radiochemistry and uses of Nuclear Energy for a public made of high school students. The EAEN project represents a pioneering program on science education and dissemination of knowledge, conducted by researchers and focused mainly on high school and scientific education for the population in general. The school’s priority is to explore the failures and the lack of education in the dissemination of nuclear energy for high school students as well as to attract prospective students with great potential for graduate courses of IPEN and other institutions in Sao Paulo and in Brazil.

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A micro DSC analyzer fitted with special high-pressure vessels was used to investigate the kinetics of methane hydrate formation in the water phase dispersed as a stable emulsion in deep offshore drilling fluids. At high sub-cooling conditions, the peak of hydrate formation is perfectly visible and regular-shaped, and could be fitted by a Gaussian law. The average time for hydrate crystallization of the water droplets’ population was represented as a logarithmic function of the inverse of absolute temperature. At low sub-cooling conditions, the formation appears confused with the baseline; the amount of hydrate formed was thus measured from its enthalpy of dissociation, after periods of formation of variable duration.

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Three batch compositions of pure oxides (SiO2, Fe2O3, PbO, Na2O) with equivalent SiO2, Fe2O3 and PbO contents and a gradually increased Na2O content were vitrified through heating in a high temperature electric furnace and subsequent quenching. The resulting vitreous products were thermally treated in order to study the devitrification behaviour, under conditions designated from differential thermal analysis experiments. Depending on the Na2O content, crystal phase separation gave rise to the growth of acmite and hematite or maghemite. A uniformly phase separated glass-ceramic material, with crystallites of similar size and population density, was produced from devitrification of the vitreous product with the higher Na2O content.

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