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Abstract  

In the present work, determination of mercury in the head hair of populational groups living near a heavily industrialized region in São Paulo and of Indians living in the Xingu park in the Amazonic region, was carried out by instrumental neutron activation analysis. A control group of people with no suspicion of contamination by mercury was also studied. The range of mercury concentrations found up to now were: for the control group from 0.26 to 02.5 ppm; for the Indians from 6.9 to 34 ppm, and for the industrialized region inhabitants: from 0.30 to 3.0 ppm.

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Abstract  

Skin as a manageable organ can provide direct or indirect information of tissue iron overload resulting from inherited disorders as hemochromatosis. Patients with hemochromatosis were evaluated at three consecutive phases along the therapy programme. Nuclear microprobe techniques were used to assess skin iron and Total Reflection X-ray Fluorescence to determine the plasma iron concentrations. Results showed that iron pools were differently correlated at the three therapy phases. These variations highlighted the value of skin iron content to assess organ iron deposition and therapy efficacy. Skin iron content can be used for a better management of patients with iron overload pathologies.

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Abstract  

The standard molar enthalpy of formation of crystalline di-isobutyldithiocarbamate complexes of P, As, Sb and Bi(III) has been derived by solution calorimetry at 298.15 K. The corresponding standard molar enthalpies of sublimation were estimated by means of differential scanning calorimetry. From the standard molar enthalpies of formation of the gaseous chelates the homolytic and heterolytic mean metal-sulphur bond-dissociation enthalpies were calculated.

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Abstract  

The elemental microdistributions of peripheral and central parts of the lichen Flavoparmelia caperata exposed to industrial pollution were analysed, in order to better understand the elements distribution patterns in relation to the lichen constitution, thereby increasing our knowledge on uptake and release mechanisms. Nuclear microscopy techniques were used to visualize elemental distributions in sample transepts and associate their concentrations to sample morphology. The distribution data of the elements studied suggests there is biological regulation of internal concentrations. Considering thallus parts, element-specific internal translocation should be taken into account as one more factor affecting lichen “memory length”.

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CeO2-catalyzed ozonation of phenol

The role of cerium citrate as precursor of CeO2

Journal of Thermal Analysis and Calorimetry
Authors: M. F. Pinheiro da Silva, L. S. Soeira, K. R. P. Daghastanli, T. S. Martins, I. M. Cuccovia, R. S. Freire, and P. C. Isolani

Abstract

Three different cerium citrate-based precursors were used for synthesizing CeO2 through thermal treatment. Three morphological types of CeO2 were obtained. Characterization of these oxides was carried out by XRD patterns, SEM microscopy, N2 adsorption isotherms, Raman spectroscopy, zeta potential, and UV/Vis luminescence. Ozonation of phenol catalyzed by CeO2 was studied as a representative reaction of environmental interest. The differences on the catalytic activity showed by these three oxides could be correlated to amounts of Ce3+ on CeO2 surface and, consequently, to the demand for oxygen needed to burn each precursor.

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This study aimed to optimize and validate methods for the analysis of thiamin and folic acid in fortified rice, pure and mixed to the milled rice (raw and cooked). The analysis was performed by high-performance liquid chromatography coupled to a diode array detector (HPLC—DAD). Different mobile phases were tested. Different ratios of organic modifier, pH ranges, triethylamine concentrations, and flow rates were used. For the validation, tests of recovery, repeatability, linearity, limit of detection (LOD), and limit of quantification (LOQ) were performed. The optimized methods showed good resolution of vitamins’ peaks, excellent recovery (82.6 to 104%), repeatability with relative standard deviation of peak areas, and retention times less than 10% and high coefficients of determination (0.9998 for thiamin and 0.9997 for folic acid). The LOD and LOQ were 0.00193 μg and 0.0193 μg for thiamin and 0.000934 μg and 0.00934 μg for folic acid. The optimized methods demonstrated reliability and sensitivity in the detection and quantification of these vitamins in fortified rice, pure and mixed to milled rice (raw and cooked). Furthermore, the methods were performed in isocratic mode, with short run time (<13 min), reflecting positively on the economy of reagents and analysis times.

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Journal of Thermal Analysis and Calorimetry
Authors: J. R. Botelho, A. G. Souza, A. D. Gondim, P. F. Athayde-Filho, P. O. Dunstan, C. D. Pinheiro, E. Longo, and L. H. Carvalho
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