Survey of trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) in retail samples of flavoured and bottled waters

Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p<0.001) were only apparent for Mn. The Mann–Whitney U-test was used to search for significant differences between flavoured and natural waters. The concentration of each element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p<0.05). Fruit juice can also be correlated to the increase of Co and As. Sweeteners did not provide any significant difference in Mn, Co, Se and Si content.

Facile synthesis of freestanding Si nanowire arrays by one-step template-free electro-deoxidation of SiO2 in molten salt

This communication presents a novel kind of silicon nanomaterial: freestanding Si nanowire arrays (Si NWAs), which are synthesized facilely by one-step template-free electro-deoxidation of SiO2 in molten CaCl2. The self-assembling growth process of this material is also investigated preliminarily.

Integration of TCP/IP and PROFIBUS protocols

Recent technological developments are pulling fieldbus networks to support a new wide class of applications, such as industrial multimedia applications. These applications are usually supported by the widely used TCP/IP stack. It is thus essential to provide support to TCP/IP based applications, in fieldbus networks. This paper presents an effort that is being carried out to integrate the TCP/IP and PROFIBUS stacks, in order to support industrial multimedia applications, whilst guarantying the timing requirements of control-related traffic.

Automated design of microwave discrete tuning differential capacitance circuits in Si-integrated technologies

A genetic algorithm used to design radio-frequency binary-weighted differential switched capacitor arrays (RFDSCAs) is presented in this article. The algorithm provides a set of circuits all having the same maximum performance. This article also describes the design, implementation, and measurements results of a 0.25 lm BiCMOS 3-bit RFDSCA. The experimental results show that the circuit presents the expected performance up to 40 GHz. The similarity between the evolutionary solutions, circuit simulations, and measured results indicates that the genetic synthesis method is a very useful tool for designing optimum performance RFDSCAs.

A imagem de si e o reconhecimento dos outros: o professor do 1º Ciclo do Ensino Básico

O tema da identidade é induzido pela pergunta: quem sou eu? Quem somos nós? Ser professor depende da imagem que o professor tem de si mesmo e da imagem social que lhe reconhece essa categoria. Pretendemos, nesta comunicação, encontrar uma interface de representações que traduzam a identidade profissional docente do professor do 1º Ciclo do Ensino Básico pelo seu olhar e pelo olhar dos outros. Recorremos a “avaliação 360 º” que envolve Professores, Encarregados de Educação, Presidentes do Conselho Directivo, Formadores e Director de Centro de Formação. Abordar o professor na actualidade significa constatar novas representações do ensino, do acto de ensinar e do saber dos professores, significa prever novos rumos para a escola, novos modos de educação e de gestão do trabalho docente. Concluiu-se que o sistema educativo caminhará para a excelência a partir do momento em que todos os seus participantes estiverem alinhados com a mesma missão para atingirem a visão da educação que melhor serve a sociedade.