Resumo: Este artigo apresenta resultados de uma pesquisa que procurou identificar as diferentes concepções epistemológicas que se encontram incorporadas à prática profissional de professores de ciências. Como resultado, tem-se que existem, em diferentes proporções, convivendo nas escolas, concepções epistemológicas distintas, sugerindo a ocorrência de uma crise paradigmática que pode justificar dificuldades para o aprendizado das ciências. A pesquisa reafirma a necessidade de se incluírem estudos da epistemologia e da história das ciências nos cursos de formação de professores e acrescenta a necessidade de se incluírem estudos sociológicos sobre o currículo, tendo em vista o caráter social da construção do conhecimento no paradigma que busca se impor.Palavras-chave: Concepções dos professores. Ensino de ciências. Epistemologia. Natureza da ciência.Abstract: This paper shows outcomes of a research that aimed to identify the different epistemological conceptions incorporated into the professional practice of science teachers. As a result, there are, in different proportions, living in the schools, distinct epistemological conceptions, suggesting the occurrence of a paradigmatic crisis, justifying the difficulties in learning science. This research reaffirms the necessity of including studies of the epistemology and the history of science in initial teachers training courses, and adds the necessity to include also sociological studies, especially those about the curriculum, bearing in mind the social character of the construction of the knowledge in the paradigm that one wants to encourage.

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Biocorrosion means any process of corrosion in wich microorganisms are somehow involved. As far as the petroleum industry is concerned, the anaerobic type is the more important, with Sulphate-Reducing Bacteria (SRB) accouting for half of the described processes. SRB are obligate anaerobs that use sulphur, sulphate or other oxidized sulphur compounds as oxidizing agents when decomposing organic material. A typical product of SRB metabolism, hydrogen sulphide -H2S-, is extremely toxic. In the present work we review the literature on mechanisms underlying biocorrosive process in wich SRB are involved and summarize some of the ultrastructural and eletrochemical work developed using SRB obtained from water injection flow in wells located on PETROBRAS offshore marine plataforms, sampled directly in the field over metallic probes, or cultured under laboratory conditions. Biofilms develop when SRB adhere to inert surfaces. A high diversity of morphological types is found inside these biofilms. Their extracellular matrix is highly hydrated and mainly anionic, as shown by its avid reaction with cationic compounds like ruthenium red. We have noted that variations in iron contet lead to interesting changes in the ultrastructure of the bacterial cell coat and also in the rate of corrosion induced in metallic test cupons. Since routine methods to prevent and treat SRB contamination and biodeterioration involve the use of biocides that are toxic and always have some environmental impact, an accurate diagnosis of biocorrosion is always required prior to a treatment decision. We developed a method that detects and semi-quantifies the presence of living or dead SRB by using free silver potentials as an indicator of corrosive action by SRB-associated sulphides. We found a correlation between sulphide levels (determined either by spectrophotometry, or using a silver electrode -E(Ag)- that measured changes in free potentials induced by the presence of exogeneously added sulphide) and SRB concentration (enumerated by a culturing method). E (Ag) was characterized under a variety of conditions andwas found to be relatively immune to possible interference resulting from aeration of media or from the psence of iron corrosion products. The method offers a simple, rapid, and effective means of diagnosing biocorrosive processes prior to their control

Este artigo descreve um processo de pesquisa que buscou encontrar, nos centros e museus de ciências, contribuições para a educação científica formal. Foi realizado na forma de pesquisa-ação com a participação, como pesquisadores, de 10 (dez) estudantes de cursos de Licenciatura (em física, química e matemática) que procuraram identificar, nos equipamentos interativos disponíveis nesses espaços, aqueles que permitissem a realização de experimentos e pudessem ser reproduzidos nas escolas. Os resultados são discutidos em relaçãoà presença dos diferentes campos do conhecimento nos museus e centros de ciências (cerca de 80% desses experimentos são de física) e a forma como os equipamentos interativos lá existentes podem ser usados como recursos para a educação formal em ciências. Como conclusão, tem-se que esses equipamentos ultrapassam o papel de experimentos de baixo custo para escolas sem laboratórios, possibilitando experimentos estimulantes que trazem aos alunos a satisfação de encontrar respostas para questões que os intrigam. Palavras-chave: ensino de ciências, equipamentos interativos, experimentos didáticos, centros de ciências.This article describes a research process that sought to find, in centers and museums of science, contributions for the formal scientific education. It was realized in the form of action-research with the participation, as researches, of 10 (ten) students of Teaching Formation Courses (in physics, chemistry and mathematics) are looking for researchers interactive equipments available on these spaces, the ones that allow the realization of experiments that could be reproduced in schools. The results are discussed in relation to the presence of the different fields of knowledge in the museums and centers of science (about 80% of these experiments are of physics) and to the form as the interactive equipments there presents can be used as resources for the formal education in sciences. As a conclusion, these equipments go beyond the role of low cost experiments for schools without laboratories, allowing stimulants experiments that bring out the students the pleasure to finding answers for questions that intrigue them. Keywords: science teaching, interactive equipments, didactic experiments, centers of science. IntroduçãoA partir do que se convencionou chamar de crise no ensino de ciências, identificada como o reiterado fracasso escolar nestas disciplinas e o afastamento dos jovens das carreiras científicas, diversos autores têm proposto que a educação em ciência assuma a pesquisa como um princípio educativo, buscando aproximar os estudantes dos métodos e processos científicos (Refs. [1-10], entre outros).A experimentação faz parte de um conjunto de aspectos relativos ao processo ensino-aprendizagem das ciências que alguns autores têm chamado de consenso construtivista na educação em ciência [6], compreendendo ainda a aprendizagem de conceitos, a resolução de problemas e a atitude em relaçãoàs ciências. Na perspectiva construtivista,é através da experiência adequadamente escolhida e criati...