Total concentration of uranium and thorium in some Brazilian soils

As amostras dos horizontes diagnósticos superficiais (A) e subsuperficiais (B) de 15 perfis de solos brasileiros foram analisadas com respeito aos teores de U e Th, extraídos após digestão com Aqua regia, pela técnica de ICP-MS. Os teores de U e Th, determinados no horizonte A, variaram, respectivamente, de 0,001 a 2,115 mg/kg e de 0,003 a 38,080 mg/kg e no horizonte B, respectivamente, de 0,003 a 2,298 mg/kg e de 0,071 a 42,090 mg/kg. Foram verificadas correlações significativas e positivas entre os dois elementos analisados com os teores de ferro e de argila nas 30 amostras analisadas.Samples from superficial (A) and subsuperficial (B) diagnostic horizons of 15 Brazilian soils were analysed to determine the content of U and Th (on a dry weight basis) by ICP-MS following digestion with Aqua regia. A range of 0.003 to 38.080 mg/kg for Th and 0.001 to 2.115 mg/kg for U, and 0.003 to 2.298 mg/kg for U and 0.071 to 42.090 mg/kg for Th were obtained for the A and B horizons, respectively. Positive and significant correlation coefficients were found between the two elements and iron and clay contents for the 30 soil samples analysed

Determination of nitrate in lettuce by ion chromatography after microwave water extraction

Lettuce is worldwide known as the most important vegetable. In this context, most farmers are searching new techniques for best quality products including hydropony. However, nitrate is of great concern, since it has a negative impact on human metabolism. The main objective of the present work was to evaluate the nitrate content of lettuce produced by conventional and hydroponic systems. The determination was conducted by ion chromatography and a new method of extraction was tested using microwave oven digestion. The results indicated that nitrate level produced in the conventional system was lower than in the hydroponic system

Antimicrobial and fluoride release capacity of orthodontic bonding materials

OBJECTIVE: The aim of this study was to evaluate the antimicrobial and fluoride releasing capacity of 3 bonding materials. MATERIAL AND METHODS: Thirty nine specimens with standardized surface smoothness and dimensions were prepared. The antimicrobial capacity of the materials against S. mutans, L. casei and C. albicans was evaluated by determining the percentage of growth inhibition of these microorganisms in an inoculated medium, obtained by optical density readouts on a spectrophotometer. The potential to interfere in microbial growth on the surface of the studied materials was observed by means of scanning electron microscopy (SEM). The fluoride release capacity in ultrapure water for 14 days was analyzed by means of ion chromatography. RESULTS: The PLUS group presented the highest percentage of microbial inhibition and the most contamination-free surface. The FUJI group presented the best fluoride release capacity. CONCLUSIONS: The TransbondTM Plus Color Change was the one that presented the best general behavior considering the evaluated aspects