Crystalline Silica
Mostrando 25-36 de 55 artigos, teses e dissertações.
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25. Exposição ocupacional à sílica e silicose entre trabalhadores de marmorarias, no município de São Paulo / Occupational exposure to silica and silicosis among sheds workers in Sao Paulo
Objetivo. No Brasil encontram-se em crescimento os índices de prevalência das doenças crônicas causadas pela exposição dos trabalhadores a poeiras minerais. Realizou-se estudo com objetivo de avaliar as condições de trabalho e de saúde dos trabalhadores em marmorarias e propor ações preventivas. Métodos. Realizou-se estudo transversal em 27 marmo
Publicado em: 2006
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26. Potencial da cinza do bagaço da cana-de-açúcar como material de substituição parcial de cimento Portland / Potential of the sugarcane bagasse ash as a partial replacement material for cement Portland
This study was carried out to evaluate the potential of the sugarcane bagasse ash (CBC) as partial replacement material for the Portland cement in mortar. A residue generated at the Jatiboca sugar mill located in Urucânia county-MG was used as CBC. The use of the sugarcane bagasse as an ash source for mineral addition into cement-based materials is subjecte
Publicado em: 2006
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27. Dilatometric studies of (SiO2-RE2O3-Al2O3) silicon carbide ceramics
Silicon carbide is an important structural ceramic and finds applications as abrasives, as a refractory and in automotive engine components. This material can attain high densities during liquid phase sintering if suitable additives are used. Silicon carbides containing silica, alumina and rare earth oxides have suitable characteristics to promote liquid pha
Materials Research. Publicado em: 2005-06
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28. Characterization of the aquifers in the crystalline environment on the west plot of the Alto Tiete Basin. / Caracterização dos aqüíferos em meio cristalino da porção oeste da Bacia do Alto Tietê
An area of 1140 km2 in the Alto Tietê basin, downstream from the city of São Paulo, between UTM coordinates 7420/7382 km South and 298/328 km West, was studied in order to characterize the fissural aquifers of the region and correlate hydrogeological parameters with diverse other factors conditioning productivity. The area includes geological compartments
Publicado em: 2005
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29. Propriedades espectrais das plantas no infravermelho termal (2,5 - 14 um): da química ao dossel. / Spectral properties of plants in the thermal infrared (2.5 - 14 um): from the chemistry to the canopy.
This work explores the thermal infrared spectral properties of plants to evaluate how such data might be used in laboratory, field, and remote sensing studies of ecosystems, and to analyze diverse chemical aspects of plant species. Attenuated total reflectance (ATR) spectra of plant leaves display absorption bands caused by the fundamental molecular vibratio
Publicado em: 2005
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30. Occupational risk for laryngeal cancer / "Riscos ocupacionais para o câncer de laringe: um estudo caso-controle"
Laryngeal cancer comprises 3,1% of the new cases of cancer in men in the world, representing the tenth most common malign neoplasm for males. In São Paulo City, 169 new cases of laryngeal cancer were reported in 1970, representing 25,5/100.000 and 299 cases in 1985, increasing the rate to 37,6/100.000 (both for males, age standardized truncated rate, 30-74
Publicado em: 2003
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31. Sinteses de cordierita por sol-gel utilizando TEOS ou acido silicico : a influencia do acido citrico na cristalização
Cordierite (2MgO.2Al2O3.5SiO2) is a strategically important glass-ceramics with interesting mechanical, thermal and chemical properties. The addition of organic acids on ceramic material precursors obtained by sol-gel synthesis has been reported. Additives can modify temperature and rate of cordierite crystallization, as well as the crystalline phase yeld. T
Publicado em: 2003
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32. Estudo fitoquÃmico e biolÃgico da hyptis mutabilis salz:(lamiaceae) / Phytochemistry and biological study of hyptis mutabilis
Crude extract of different parts of Hyptis mutabilis obtained using solvent of different polarities were submitted to the anti-microbial screening against 21 microorganisms from Departmental collection and clinically isolated to select the one with largest activity for phytochemistry studies. For MIC determination the extracts that presented halos above 14 m
Publicado em: 2003
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33. Densification studies of silicon carbide-based ceramics with yttria, silica and alumina as sintering additives
Silicon carbide has been extensively used in structural applications, especially at high temperatures. In this work, Y2O3, Al2O3 and SiO2 were added to beta-SiC in order to obtain highly dense ceramics. Sintering was conducted in a dilatometer and in a graphite resistance furnace and the densification behaviour was studied. Sintered samples were characterise
Materials Research. Publicado em: 2001-10
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34. Sintese e caracterização de preformas de silica-germania obtidas por deposição fase-vapor (VAD)
This research reports the study of deposition parameters of V AD (Vapor -phase Axial Deposition) silica-germanium and their correlation with structural properties. Characterization studies were conducted by small-angle X-ray scattering (SAXS), X-ray difftaction (XRD), scanning electronic microscopy (SEM), and X-ray fluorescence spectroscopy (XRF). The result
Publicado em: 2001
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35. "Películas Espessas de Carbeto de Silício, SiC, sobre Mulita" / Silicon carbide, SiC, thick films over mullite.
Crystalline silicon carbide, SiC, films were deposited on mullite by atmospheric pressure chemical vapor deposition (CVD) method. The characteristic of substrate surface determinate if the film will be dense or porous, while the deposition temperature defines its crystalinity and nucleation rate in film formation. During the mullite substrate preparation pro
Publicado em: 2001
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36. Estados críticos orientacionais em cristais líquidos liotrópicos induzidos por campos magnéticos. / Orientations critical states in lyotropic liquid crystals induced by magnetic fields.
Liquid crystalline structures are found in materials made from molecules which are anisotropic in shape; such material are characterized mainly by a long range orientational order. In the nematic phase, the rodlike molecules tend to align parallel to each other. The average orientation defines a unit vector, called director n. Lyotropic liquid crystals are u
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/12/2000