985 resultados para Sociedade irregular


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Morphological and spectroscopic studies of Sr2CeO4 blue phosphor in the form of fine particles prepared from a powdered multi-component precursor, via a combustion method, are reported. Samples were also prepared through a solid-state reaction and from a polymeric precursor for comparison. Citric acid or glycine as fuels in the combustion method lead to a mixture which is heated at 950 ºC for 4 h, resulting in spheroidal particles with a diameter between 250-550 nm. Samples from the polymeric precursor result in spheroidal particles (350-550 nm) and from the solid-state reaction in irregular particles (~ 5 mum). Therefore, the combustion method is adequate for preparation of Sr2CeO4 in the form of spherical fine particles.

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In this paper, we present and discuss the chemist's education profile in Brazil from the points of view of the academy and the industry. We emphasize that the chemistry courses need urgently to face the following challenge: to improve the undergraduate's interdisciplinary approach, management abilities and interpersonal relationships.

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This article offers an overview on the historical facts and the recent state of the Regional Secretaries and the Scientific Divisions in the course of 30 years of SBQ.

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This paper presents some aspects involved in the internationalization of SBQ. The importance of journals, meetings and agreements in this process is discussed.

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In this work Fenton and photo-Fenton processes for textile dye degradation were investigated using iron (II) immobilized in alginate spheres. Photomicrographs obtained by scanning electron microscopy showed an irregular and porous surface with a homogeneous distribution of iron. The Fenton process was used to evaluate the degradation efficiency of reactive dyes and this procedure showed a low degradation effect. The association of artificial visible light or solar radiation in the Fenton process (foto-Fenton process) showed degradation ratios of 70 and 80% respectively in 45 min. It was also observed that the iron-alginate matrix can be reused.

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This paper discusses the Brazilian academic production on Chemical Education. The main source of information is the annual meeting of the Brazilian Chemical Society (RASBQ) covering the period 1999-2006. All the papers presented by the Division of Chemical Education of the RASBQ were reviewed to permit a discussion about the development of the area in Brazil. This bibliographical revision comprises the following aspects: year of presentation, Brazilian region and institution of production, scholastic level encompassed by the study, the kind of academic work (or research type) and thematic focus of the study.

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This paper discusses of the use of the Impact Factor in the evaluation of chemistry graduate courses by CAPES and the internationalization of the Journal of the Brazilian Chemical Society and Química Nova.