Influence of synthesis conditions on carbonate entrapment in perovskite SrSnO 3

Strontium stannate (SrSnO 3 ), a perovskite material, was synthesized by the polymeric precursor method, with different routes to eliminate organic matter. The utilization of pure oxygen for the elimination of organic matter changed the Raman spectra, especially in the low frequency region. Some peaks, which were previously assigned to the perovskite phase, were not noticed when the carbonate amount was lower. On the other hand, the profile of the IR spectra and XRD patterns did not change. These results suggest that carbonate may be present inside the perovskite lattice

Representations of Portugal in Herman Hesse, Philip Roth and Paul Auster

The aim of my research is to answer the question: How is Portugal seen by non-Portuguese fictionists? The main reason why I chose this research line is the following: Portuguese essayists like Eduardo Lourenço and José Gil (2005) focus their attention on the image or representation of Portugal as conceived by the Portuguese; indeed there is a tendency in Portuguese cultural studies (and, to a certain extent, also in Portuguese philosophical studies) to focus on studying the so-called ‗portugalidade‘ (portugueseness), i.e., the essence of being Portuguese. In my view, the problem with the studies I have been referring to is that everything is self-referential, and if ‗portugueseness‘ is an issue, then it might be useful, when dealing with it, to separate subject from object of observation. That is the reason why we, in the CEI (Centro de Estudos Interculturais), decided to start this research line, which is an inversion in the current tendency of the studies about ‗portugueseness‘: instead of studying the image or representation of Portugal by the Portuguese, my task is to study the image or representation of Portugal by the non-Portuguese, in this case, in non-Portuguese fiction. For the present paper I selected three writers of the 20th century: the German Hermann Hesse and the North-Americans Philip Roth and Paul AusterO propósito da minha pesquisa é responder à questão: como é Portugal visto pelos escritores de ficção estrangeiros? A principal razão pela qual escolhi esta linha de investigação é o seguinte: ensaístas portugueses, como Eduardo Lourenço e José Gil (2005), centram a sua atenção na imagem ou na representação de Portugal tal como é concebida pelos próprios portugueses. De facto, existe uma tendência nos estudos culturais portugueses (e também, até certo ponto, nos estudos filosóficos) para se centrarem na chamada ‗portugalidade‘, ou seja, na essência de ser português. No meu ponto de vista, o problema com os estudos que referi anteriormente é que tudo é auto-referencial. E se a ‗portugalidade‘ é uma questão a ter em conta, então pode ser útil, ao estudá-la, separarmos o sujeito do objecto de observação. É esta a razão pela qual nós, no CEI (Centro de Estudos Interculturais), decidimos começar esta linha de investigação, que é uma inversão da tendência corrente dos estudos sobre a ‗portugalidade‘: ao invés de estudar a imagem ou a representação de Portugal pelos portugueses, a minha tarefa é estudar a imagem ou a representação de Portugal pelos não-portugueses, neste caso, na ficção não-portuguesa. Para este artigo seleccionei três escritores do século XX: o alemão Hermann Hesse e os norte-americanos Philip Roth e Paul Auster

Purinergic signalling and immune cells

This review article provides a historical perspective on the role of purinergic signalling in the regulation of various subsets of immune cells from early discoveries to current understanding. It is now recognised that adenosine 5'-triphosphate (ATP) and other nucleotides are released from cells following stress or injury. They can act on virtually all subsets of immune cells through a spectrum of P2X ligand-gated ion channels and G protein-coupled P2Y receptors. Furthermore, ATP is rapidly degraded into adenosine by ectonucleotidases such as CD39 and CD73, and adenosine exerts additional regulatory effects through its own receptors. The resulting effect ranges from stimulation to tolerance depending on the amount and time courses of nucleotides released, and the balance between ATP and adenosine. This review identifies the various receptors involved in the different subsets of immune cells and their effects on the function of these cells

Efeito da adição de rejeito na redução de coração negro em cerâmicas vermelhas Effect of solid waste addition in the decrease of black core occurrence in red ceramic

Um dos problemas que afeta a indústria cerâmica é a elevada perda de produtos acabados, decorrente do próprio processamento, levando a trincas e peças fora de conformidade. Deste modo, é necessário o reaproveitamento desses resíduos, como forma de reduzir o impacto ambiental. Neste trabalho, os resíduos de duas indústrias de cerâmica vermelha foram moídos e adicionados à própria massa, levando, também, a um ganho econômico. As porcentagens variaram de 10% a 30%, em peso. As peças foram conformadas por extrusão e sinterizadas a 950 ºC e 1000 ºC. Os resultados obtidos mostram que a adição levou a uma melhoria nas propriedades das amostras, pois diminuem a possibilidade de ocorrência de coração negro, levando a peças mais uniformes e menos porosas<br>One of the problems of the ceramic industry is the high level of finished product loss, due to ceramic processing, leading to cracks and materials out of conformity. In this way it is necessary to recycle these solid wastes in order to reduce the environment impact. In this work, the solid waste of two red ceramic industries were milled and incorporated to the formulation of the industry, leading also to an economic gain. Incorporation percentages varied from 10% to 30 wt %. Samples were processed by extrusion and sintered at 950 ºC and 1000 ºC. The results indicate that the addition led to an improvement of sample properties, due to the decrease of black core formation, producing samples with higher uniformity and lower porosity

Chemical modification of the surface of alumina with alkaline earth metal oxides using the polymeric precursor method for catalysis application

In this study, modifications of alumina surface with of alkaline earth metal oxides were studied, using the polymeric precursor method. The modified compounds were characterized by X-ray diffraction, nitrogen adsorption-desorption and scanning electron microscopy. The catalytical properties of these new catalysts were evaluated for the transesterification reaction of babassu oil. It is observed that the transesterification reaction of babassu oil with methanol was successfully carried out using the modified alumina samples.Neste trabalho foram estudadas modificações da superfície de alumina com óxidos de metais alcalino-terrosos, usando o método dos precursores poliméricos. Os compostos modificados foram caracterizados por difração de raios X, adsorção-dessorção de nitrogênio e microscopia eletrônica de varredura. As propriedades catalíticas desses novos catalisadores foram avaliadas para a reação de transesterificação de óleo de babaçu. Foi observado que a reação de transesterificação de óleo de babaçu com metanol ocorreu com sucesso na presença das aluminas modificadas

Color and structural analysis of CoxZn7-xSb2O12 pigments

The polymeric precursor method was successfully used to synthesize CoxZn7-xSbO12 (x = 0-7) powders. Pigments were evaluated using colorimetry, X-ray diffraction, UV-vis and infrared spectroscopy. The optical band gap values vary with the Co2+ substitution. These results suggest that the concomitant presence of Co and Zn in the spinel lattice leads to the rupture of the Vegard law, as well as other properties of the studied system, such as unit cell volume. The Co-richer samples display a higher absorbance than the Co-lean samples. The high absorption of the Co7Sb2O12 sample at most of the visible region makes this compound a candidate for a black pigment. It was shown that color depends on the site where the chromophore ion is located, in agreement with the ligand field theory. (c) 2006 Elsevier Ltd. All rights reserved

Propiedades ópticas del pigmento α-Fe₂O₃/SiO₂

Presently work describes the synthesis of the pigment α-hematites/SiO2 according to the method of mixture of oxides. The red color of the pigment corresponds to the transitions electronic 6A1g→4T1g y 6A1g→4T2g of the ion Fe+3 that presents the configuration structural d5 and it is connected to six oxygen in the structure of the hematites. The changes in the shade of the red color of the pigment are related with the in the entropy do system and consequent decrease of the “ bandgap “. The compound α-hematites/SiO2 it was shown as a promissory ceramic pigment for application to the temperature of 1100°C.En el presente trabajo describimos la síntesis del pigmento α-hematites/SiO2 según el método de mezcla de óxidos. El color rojo del pigmento corresponde a las transiciones electrónicas 6A1g→4T1g y 6A1g→4T2g del ion Fe+3 que presenta la configuración estructural d5 y está enlazado a seis oxígenos en la estructura de la hematites. Los cambios en el matiz del color rojo del pigmento están relacionados con la entropía del sistema y con la disminución consecuente del gap. El compuesto α-hematites/SiO2 se mostró como un pigmento cerámico promisorio para aplicación a la temperatura de 1100°C