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- Author or Editor: S. M. Ma x
- Chemistry and Chemical Engineering x
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Abstract
The effect of gamma-radiations on bilirubin, in vitro, has been studied. It was found that gamma-radiation causes oxidation of bilirubin to biliverdine as one of the products. The likely implication of this effect in transformation of bilirubin to excretable products, in vivo, in case of jaundice is discussed.
Abstract
Archaeological ceramic fragments from Água Limpa site, in São Paulo, Brazil, were analyzed using instrumental neutron activation analysis. Multivariate statistical methods including Pearson correlation coefficient, cluster and principal components analysis were used to interpret the concentration data. Rare earth and alkaline elements were highly correlated. Six principal components explained 74.9% of the total variance and five clusters were found. The sample chemical composition showed that all samples have the same provenance.
Abstract
In a preliminary study performed with the waste rocks from the future uranium mine to be explored in Brazil, 106 samples were taken from the eight main lithologies found in the massif and analysed by instrumental neutron activation analysis (INAA) for 20 elements. For samples from the same lithology, a high variability in the concentration of most of the elements was found (coefficient of variation larger than 20%), which might be attributed to either insufficient homogenisation of minerals or to local variation within lithology. The hypothesis that the variability within the lithology does not have an influence to the total variability was tested by analysing 5 replicates of the 5 most contrasting samples from the predominant lithology (plagioclase-microcline-gneiss), chosen after applying statistical evaluation (principal components and cluster analyses). Results indicated that homogenisation of samples was adequate due to low variation among replicates. The hypothesis tested was rejected with a confidence level higher than 99% for all the elements, corroborating the large intra-lithology variability.
Abstract
The k 0 parametric neutron activation analysis has been applied since 1995 in the Radiochemical Sector/CDTN, Belo Horizonte, Brazil. Several certified reference materials were studied with the aim of analysing biological samples. This work is related to an IAEA co-ordinated research project whose goal is to make a survey of the exposures to metals related to occupational diseases. It has been conducted by CDTN and government departments of health. The hair samples as bioindicators were donated by galvanising factory workers in Belo Horizonte. This city and surrounding area are important industrial centres and that industry is responsible for the majority of patients who look for medical assistance because of metal contamination. The Al, Co, Cu, Cr, La, Mn, Sb and V concentrations determined in the workers' samples suggest endogenous contamination.
