5 research outputs found

    Growth of BiVO4 particles in cellulosic fibres by in situ reaction

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    Cellulosic fibres were used to obtain well-defined BiVO4 particles using a simple controlled precipitation method; microscopy analysis suggests that the BiVO4 particles grow from nucleation sites located in the cell wall structure and inside the lumen of fibres

    Cellulose/iron oxide hybrids as multifunctional pigments in thermoplastic starch based materials

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    Cellulose/iron oxide hybrids were prepared by the controlled hydrolysis of FeC2O4 in the presence of vegetable and bacterial cellulose fibres as substrates. By varying the relative amount of FeC2O4 and NaOH, either hematite or magnetic iron oxides were grown at the cellulose fibres surfaces. This chemical strategy was used for the production of a number of materials, whose coloristic properties associated to their reinforcement role allowed their use as new hybrid pigments for thermoplastic starch (TPS) based products. The TPS reinforced materials were characterized by several techniques in order to evaluate: the morphology and the compatibility between the matrix and the fillers; the mechanical reinforcement effect of the cellulose/iron oxide pigments on TPS and the coloristic properties of the composites. All materials showed good dispersion and strong adhesion for the cellulose/iron oxide nanocomposites in the TPS matrix thus resulting in improved mechanical properties

    Entre o biológico e o social: um estudo sobre os Congressos Brasileiros de Epidemiologia, 1990-2002 Between biological and social factors: a study of Brazilian epidemiology congresses, 1990-2002

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    A discussão sobre os conceitos de biológico e social na determinação do processo saúde-doença é estruturante na Saúde Coletiva no Brasil, e no campo epidemiológico. Este artigo apresenta os resultados da pesquisa qualitativa dos Anais dos Congressos Brasileiros de Epidemiologia, no período de 1990 a 2002. Tem como objetivo identificar as noções de biológico e social, neles contidos, com vistas à identificação dos pressupostos teóricos que os norteiam. Os resultados demonstraram que o conceito de social refere-se, principalmente, à esfera do 'societário', ancorado na dissociação disciplinar das ciências naturais e sociais. O biológico é atribuído à esfera individual e clínica do processo saúde-doença, raramente à esfera do coletivo, bem como um conceito portador de objetividade. Entre o biológico e o social, o ambiente aparece como categoria autônoma; o biológico aparece ainda, porém de forma embrionária, como complexo, histórico e intrinsecamente social. A análise dos resultados apontou para uma necessária redefinição de marcos teóricos que possibilitem o avanço dos conhecimentos na área e, conseqüentemente, das práticas em saúde que a Epidemiologia subsidia. O projeto de pesquisa passou pelo Comitê de Ética em Pesquisa do Instituto de Saúde SESSP, tendo sido aprovado.<br>The discussion on the concepts of biological and social factors in the determination of the health-illness process is a basic theme in Public Health in Brazil, and in the epidemiological field. This article presents the results of a qualitative research on the records of Brazilian Epidemiology Congresses in the period between 1990 and 2002. Its objective is to identify the notions of biological and social factors, seeking to recognize the theoretical assumptions underlying them. Results demonstrated that the concept of social factor is mentioned mainly in the sphere of 'societary', anchored in the dissociation between natural and social sciences. The biological factor is associated with the individual and clinical sphere of the health-illness process, seldom attributed to the sphere of collective, and it is perceived as the bearer of the concept of objectivity. In the biological-social relation, the environment appears as an independent category; the biological factor also appears, in an incipient form, as a complex, historical and intrinsically social concept. The analysis pointed toward the need for a theoretical redefinition that could enable the advancement of knowledge in the area, and, consequently, of health practices based on Epidemiology. The research project has been through the Etical Research Committee of the Instituto de Saúde SESSP and was aproved
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