Toxic Metals (Pb and Cd) and Their Respective Antagonists (Ca and Zn) in Infant Formulas and Milk Marketed in Brasilia, Brazil

In non-ideal scenarios involving partial or non-breastfeeding, cow’s milk-based dairy products are mainstream in infant feeding. Therefore, it is important to study the concentrations of potentially neurotoxic contaminants (Pb and Cd) and their respective counteracting elements (Ca and Zn) in infant dairy products. Fifty-five brands of infant formulas and milk sold in Brasilia, Brazil were analyzed. The dairy products came from areas in the central-west (26%), southeast (29%) and south of Brazil (36%) extending as far as Argentina (7%) and the Netherlands (2%). For toxic Pb and Cd, median concentrations in powdered samples were 0.109 mg/kg and 0.033 mg/kg, respectively; in fluid samples median Pb concentration was 0.084 mg/kg, but median Cd concentration was below the limit of detection and overall values were below reference safety levels. However, 62% of these samples presented higher Pb concentration values than those established by FAO/WHO. Although the inverse correlation between Cd and Zn (Spearman r = −0.116; P = 0.590) was not statistically significant, the positive correlation between Ca and Pb was (Spearman r = 0.619; P < 0.0001). Additionally, there was a significant correlation between Pb and Cd. Furthermore, the study also revealed that provision of the essential trace element Zn in infant formulas can provide adequate amounts of the recommended daily requirements. Infant formulas and milk sold for consumption by infants and children can be an efficient tool to monitor neurotoxic metal risk exposure among young children

Screen-printed back-to-back electroanalytical sensors

We introduce the concept of screen-printed back-to-back electroanalytical sensors where in this facile and generic approach, screenprinted electrodes are printed back-to-back with a common electrical connection to the two working electrodes with the counter and reference electrodes for each connected in the same manner as a normal “traditional” screen-printed sensor would be. This approach utilises the usually redundant back of the screen-printed sensor, converting this “dead-space” into a further electrochemical sensor which results in improvements in the analytical performance. In the use of the back-to-back design, the electrode area is consequently doubled with improvements in the analytical performance observed with the analytical sensitivity (gradient of a plot of peak height/ analytical signal against concentration) doubling and the corresponding limit-of-detection being reduced.We also demonstrate that through intelligent electrode design, a quadruple in the observed analytical sensitivity can also be realised when double microband electrodes are used in the back-to-back configuration as long as they are placed sufficiently apart such that no diffusional interaction occurs. Such work is generic in nature and can be facilely applied to a plethora of screen-printed (and related) sensors utilising the commonly overlooked redundant back of the electrode providing facile improvements in the electroanalytical performance

A importancia do capital de risco para o recente boom de IPOs (1004-2007) no Brasil

O Brasil viveu recentemente um forte movimento de aberturas de capital na Bolsa de Valores de São Paulo (Bovespa), que saltou de 7 novas aberturas (R$4,5 bilhões) em 2004 para 64 (R$ 55,7 bilhões) em 2007. Este fenômeno é o que se denomina como recente boom de IP Os no Brasil. Paralelamente, também se observa um forte movimento de consolidação das empresas nacionais, com aumento do número de fusões e aquisições (F&A) em diversos setores da economia. Por trás desses dois processos, existe um agente ainda pouco conhecido no Brasil, mas que vem ganhando importância no cenário empresarial desde a década de 1990 e que vem aparentemente dando impulsão a esses dois movimentos, que é o Capital de Risco. O objetivo deste trabalho é compreender a lógica de funcionamento do capital de risco, analisando sua história no Brasil, a radiografia atual da sua indústria, um típico ciclo de investimentos e os agentes envolvidos nesse ciclo, bem como analisar a importância que o capital de risco teve nos dois fenômenos citados, em especial nas recentes aberturas de capital ocorridas no BrasilNot informe

CHEMICAL EFFECTS OF ALKALI ON GLIADIN

Abstract not availabl

Characteristics and wear mechanisms of MGO-C refractories for steel ladle slag line

Steel ladles are special vessels used for liquid steel transportation from the primary refining stage up to its solidification one at the casting shop. The MgO-C bricks have been used for lining this equipment due to its high chemical resistance to steel slags and thermal shock. However, new procedures during refining stages have increased the attack of the refractory lining, especially in the slag line, where the corrosion and wearing processes are intense. This fact has significant implications in reducing the ladle availability, leading to the need of intermediary repairs, besides increasing production costs and affecting the operational safety. In this context, the present study aims to evaluate the wear mechanisms of the steel ladle slag line by identifying the effects of some variables during the refractory production, placing and operation. In order to achieve that, the computational thermodynamics was widely used to understand the reactions and transformations that occur in complex systems, such as the interaction between refractory and slag. The software helped in evaluating the effect of raw materials, antioxidants additives and alternative materials (such as spinel) of new MgO-C ceramic compositions performance. The laboratory tests indicated the oxidation and corrosion as the main wearing mechanisms in MgOC refractory. In the first case, it was detected the importance to develop solutions for carbon protection, such as, applying a lining antioxidant coating for the first ladle heating. In addition, the slag conditioning efficiency to reduce the bricks corrosion rate was attested, due to the chemical potential decrease for dissolving the refractory constituents. Thus, this project has improved the knowledge of MgO-C behavior at high temperatures and also helped in the development of alternative solutions (focused in operational standards and formulations) to maximize the refractory performance.Panelas de aço são recipientes especiais que transportam o aço líquido desde o final do refino primário até a sua solidificação no lingotamento. Os tijolos de MgO-C têm-se destacado no revestimento destes equipamentos devido a elevada resistência química às escórias siderúrgicas e ao choque térmico. Porém, as etapas de refino têm se tornado cada vez mais agressivas aos materiais cerâmicos, principalmente na linha de escória, onde os processos de corrosão e desgaste são intensos. Este fato tem implicações significativas na redução da disponibilidade de panelas na produção e na necessidade de reparos intermediários no revestimento, além de aumentar os custos produtivos e afetar a segurança operacional. Neste contexto, o presente estudo visou avaliar os mecanismos de desgaste na linha de escória das panelas de aço, identificando os efeitos das variáveis durante a fabricação, instalação e operação dos refratários. Para tanto, a termodinâmica computacional foi amplamente utilizada para entendimento das reações e transformações que ocorrem em sistemas complexos, como no caso da interação entre refratário e escória. Esta ferramenta auxiliou na avaliação do efeito das matérias-primas, aditivos antioxidantes e materiais substitutos (como espinélio) no desempenho de novas composições cerâmicas do sistema MgOC. Os ensaios laboratoriais indicaram a oxidação e a corrosão como os principais mecanismos de desgaste dos refratários MgO-C. No primeiro caso, verificou-se a importância de soluções na proteção ao carbono do revestimento, como por exemplo, a aplicação de tinta antioxidante no primeiro aquecimento. Adicionalmente, confirmou-se a eficiência do condicionamento de escórias na redução das taxas de corrosão dos tijolos, devido a redução do potencial químico de dissolução dos constituintes dos refratários. Assim, este projeto auxiliou a compreender o comportamento do sistema MgO-C em altas temperaturas e a propor soluções que maximizem a resistência físico-química deste refratário