1000 resultados para luz Síncrotron


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Este estudo trata de indicadores de desempenho em organizações de Ciência, Tecnologia e Inovação (C, T & I) e, em particular, do Laboratório Nacional de Luz Síncrotron (LNLS). Teve por objetivo determinar os indicadores a serem utilizados pelo LNLS para garantir o atingimento de seus objetivos de curto e longo prazo. Para tanto foi realizado um estudo de caso. Os dados foram coletados por meio de entrevistas semiestruturadas junto a 10 stakeholders com elevado grau de influência e interesse na instituição, analisados pela técnica de análise de conteúdo e triangulados por meio da análise de documentos e da observação participante. Como resultado, este estudo sugere um modelo de acompanhamento de desempenho a ser adotado pelo LNLS que também pode ser útil para as demais organizações de C, T & I.

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Chlorinated polymers (PVC, PVDC and E-CTFE) were irradiated with white light produced at the Brazilian Synchrotron Light Source (LNLS). The emitted gases were analyzed by mass spectrometry. The spectra were dominated by peaks related to hydrochloric acid, HCl, and chlorine (35Cl). The measured HCl intensity is used to evaluate the sensitivity of the polymers over a broad energy range. PVDC showed the greatest light sensitivity as compared to PVC and E-CTFE.

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The photofragmentation of a core-excited halogenated compound, Halotane (C2F3HClBr), generally used as anesthetic by inhalation, has been studied using high energy photons and electrons near C 1s ionization edge (~ 300 eV), using time-of-flight mass spectrometry in multicoincidence mode. We observe strong differences between the molecular fragmentation induced by photons and electron impact.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The present work has as its basic purpose observing the principal administrative changes originated from the implementation of the Social Organization Project, inserted in the recent administrative reforms in Brazil, proposed from the Director Plan of the State Reform and approved by the National Congress in November of 1995. In the course of the text will be presented the main factors of the transformation from a bureaucratic public administration to a managerial public administration, specifically focusing the change from a Government Organization to a Social Organization. To reach the proposed objective, a case study of the Brazilian Association of Light Sincrotron Technology - ABTLuS, that represented the first Social Organization installed in Brazil, responsible for the management of the National Laboratory of Light Sincrotron - LNLS, under form of administration contract signed with Nationl Research Council - CNPq and Science and Technology Ministry - MCT. Initially, was developed the theoretical framework, based on the existent literature. Proceeding, field researches were realized in the cities of Campinas - SP, in Brasília - DF and in Rio de Janeiro - RJ. As a consequence of the accomplished work, it was possible to observe that the implementation of the SO administrative model brought more administrative flexibility for the qualified institution. This fact induced to gains of agility and efficiency, with more responsibilities, for the leaders as well as for the employees of ABTLuS. As for the other two important items consisted in the Director Plan, related with the cultural change (from bureaucratic to managerial) and with the social control (larger interaction in the relationship State-society), it is important to stand out the need of a larger time for evaluation, considering that the LNLS presents peculiar characteristics (subject approached in the work). The Social Organization ABTLuS counts with a little more than two years of administration contract, therefore the process is still in course.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Demand for potassium in Brazil is large and is constantly increasing, but only about 5% of all consumed potassium is produced in the country. This low domestic production implies high rate of potassium imports, leaving the country vulnerable in the event of any difficulty to import this product and currency fluctuations. The modified glauconite is a rock that has a high potential for potassium exploration, found in Minas Gerais state, its extraction is relatively cheap and the prospected rock volume is high. The difficulty for its use as a direct source of potassium is in its low solubility. Thus, the objective of this study was to perform a chemical and mineralogical characterization of the modified glauconite and evaluate the effectiveness of techniques and treatments in the potassium solubilization contained in the rock. For this study, it was used characterization techniques such as X-ray diffraction, scanning electron microscopy, diffraction by Synchrotron Light and chemical analysis of high and low power of potassium extraction. Also granulometric testing and thermal treatments with different forms of calcination were carried out. Overall, it was found that the modified glauconite is a compound of minerals, of the mica groups K-feldspar and quartz and calcination substantially alter the crystal structure of these minerals, increasing the potassium availability. While the natural solubility of glauconite modified be very low, rock calcination added with high fluxes of calcium and low magnesium content at 1200 °C led to potassium solubility increase in order of 100 times compared to that observed in the glauconite natural modified.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The relationship between the microstructure and the magnetic properties of soft magnetic materials, have been studied by different researchers who seek to employ electrical systems, increasing their life span and reduce their energy consumption. Following this same line the Brazilian Synchrotron Light Laboratory developed a new synchrotron light source, the Sirius, where magnetic materials with high magnetic permeability values are being studied for use in accelerator dipoles. The low carbon steel is a ferromagnetic material that has a great relationship between cost and magnetic permeability. Aiming to raise the values of permeability of the material, heat treatments were done and evaluated the magnetic properties, microstructure and mechanical properties to correlate them. It was noted that the thermal annealing were the most effective, and the annealing performed with a small time threshold, which only phenomenon observed was the primary recrystallisation, was the most elevated values of magnetic permeability of the material, due to the average grain size ideal achieved. The heat treatments do not guide the magnetic domains of the material and not influence the mechanical properties of the material due to lack of carbon in the microstructure. The annealing treatments were shown to be an alternative to raising the values of the magnetic permeability of the material and facilitate the implementation of ultra low carbon steel in the dipoles of Sirius

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The small angle X-ray scattering (SAXS) technique has been used with very much versatility and success in the structural characterization of nanostructured materials. The present work deals with a study of the principles of the SAXS technique and of some classical models employed in the structural characterization of nanostructured materials. Particularly, the study of the models and of the associated methodologies is applied to a set of samples of silica gels, of varied typical structures, prepared in the Laboratório de Novos Materiais of the Departamento de Física of the IGCE. The work discusses in an introductory chapter the principles of the SAXS technique and the foundation of classical models often used in the structural characterization of materials. The classical models and the associated methodologies were applied to a variety of silica gel structures. The studies include: i) the scattering from a system of particles - Guinier's law; ii) the asymptotic scattering from a two-phase system - Porod's law; iii) systematic deviation from Porod's law - Surface Fractal; iv) heterogeneities in solids with random size distribution - DAB Model; and v) the scattering from mass fractal structures. The analyses were carried out from experimental SAXS data obtained in several opportunities at the Laboratório Nacional de Luz Síncrotron (LNLS)