2 resultados para Lead industry and trade

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)


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Accessibility has become a serious issue to be considered by various sectors of the society. However, what are the differences between the perception of accessibility by academy, government and industry? In this paper, we present an analysis of this issue based on a large survey carried out with 613 participants involved with Web development, from all of the 27 Brazilian states. The paper presents results from the data analysis for each sector, along with statistical tests regarding the main different issues related to each of the sectors, such as: government and law, industry and techniques, academy and education. The concern about accessibility law is poor even amongst people from government sector. The analyses have also pointed out that the academy has not been addressing accessibility training accordingly. The knowledge about proper techniques to produce accessible contents is better than other sectors`, but still limited in industry. Stronger investments in training and in the promotion of consciousness about the law may be pointed as the most important tools to help a more effective policy on Web accessibility in Brazil.

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The performance of a carbon paste electrode (CPE) modified with SBA-15 nanostructured silica organofunctionalised with 2-benzothiazolethiol in the simultaneous determination of Pb(II), Cu(II) and Hg(II) ions in natural water and sugar cane spirit (cachaca) is described. Pb(II), Cu(II) and Hg(II) were pre-concentrated on the surface of the modified electrode by complexing with 2-benzothiazolethiol and reduced at a negative potential (-0.80 V). Then the reduced products were oxidised by DPASV procedure. The fact that three stripping peaks appeared on the voltammograms at the potentials of -0.48 V (Pb2+), -0.03 V (Cu2+) and +0.36 V (Hg2+) in relation to the SCE, demonstrates the possibility of simultaneous determination of Pb2+, Cu2+ and Hg2+. The best results were obtained under the following optimised conditions: 100 mV pulse amplitude, 3 min accumulation time, 25 mV s(-1) scan rate in phosphate solution pH 3.0. Using such parameters, calibration graphs were linear in the concentration ranges of 3.00-70.0 x 10(-7) mol L-1 (Pb2+), 8.00-100.0 X 10(-7) mol L-1 (Cu2+) and 2.00-10.0 x 10(-6) mol L-1 (Hg2+). Detection limits of 4.0 x 10(-8) mol L-1 (Pb2+), 2.0 x 10(-7) mol L-1 (Cu2+) and 4.0 x 10(-7) mol L-1 (Hg2+) were obtained at the signal noise ratio (SNR) of 3. The results indicate that this electrode is sensitive and effective for simultaneous determination of Pb2+, Cu2+ and Hg2+ in the analysed samples. (C) 2008 Published by Elsevier B.V.