855 resultados para Géis de silicone
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In different regions of Brazil, population growth and economic development can degrade water quality, compromising watershed health and human supply. Because of its ability to combine spatial and temporal data in the same environment and to create water resources management (WRM) models, the Geographical Information System (GIS) is a powerful tool for managing water resources, preventing floods and estimating water supply. This paper discusses the integration between GIS and hydrological models and presents a case study relating to the upper section of the Paraíba do Sul Basin (Sao Paulo State portion), situated in the Southeast of Brazil. The case study presented in this paper has a database suitable for the basin's dimensions, including digitized topographic maps at a 50,000 scale. From an ArcGIS®/ArcHydro Framework Data Model, a geometric network was created to produce different raster products. This first grid derived from the digital elevation model grid (DEM) is the flow direction map followed by flow accumulation, stream and catchment maps. The next steps in this research are to include the different multipurpose reservoirs situated along the Paraíba do Sul River and to incorporate rainfall time series data in ArcHydro to build a hydrologic data model within a GIS environment in order to produce a comprehensive spatial-temporal model.
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Selecting a suitable place to install a new landfill is a hard work. Bauru is a Brazilian municipality where the local landfill currently in use has a life span that is almost over, and the selection of a new area for a future landfill is crucial and urgent. Here we use a geographic information system (GIS) approach to indicate possible suitable areas for installing the landfill. The considered criteria were: river network and the respective buffer zone, relief, urban areas and their respective buffer zone, existence of Areas for Environmental Protection (AEPs), occurrence of wells and their respective buffer zones, existence of airports and their buffer zones, wind direction, and the road network and its respective buffer zone. Due the facts that (1) Bauru has an urban area relatively large in relation to whole municipal area, (2) Bauru has two airports, and (3) this area encompasses parts of three AEPs, the model showed that there are few areas suitable and moderately suitable in Bauru, and the greater part of the municipality is unsuitable to install a new landfill. Due to this important finding reported here, the local policymakers should consider the suitable or even moderately suitable areas for analysis in situ or look for other creative solutions for destination of the solid waste. We highly encourage the use of GIS in studies that seek suitable areas for future landfills, having found that SIG was a tool that allowed fast and precise work and generated an outcome sufficiently clear of interpretation.Implications: Solid waste (SW) management is one of the main environmental concerns nowadays. Landfilling SW is still the main practice to disposal of such material. However, for many regions, suitable places for landfilling are getting scarce. This study proved this situation for a populous place in a southeastern Brazilian region. This study also showed how the decision makers should manage the problem in order to minimize the amount of SW generated and delivered for the landfill. Massive investment in education is a critical issue to reach the proposed aim.
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Polymeric insulation is an increasing tendency in projects and maintenance of electrical networks for power distribution and transmission. Electrical power devices (e. g., insulators and surge arresters) developed by using polymeric insulation presents many advantages compared to the prior power components using ceramic insulation, such as: a better performance under high pollution environment; high hydrophobicity; high resistance to mechanical, electrical and chemical stresses. The practice with silicone insulators in polluted environments has shown that the ideal performance is directly related to insulator design and polymer formulation. One of the most common misunderstandings in the design of silicone compounds for insulators is the amount of inorganic load used in their formulation. This paper attempts to clarify how the variation of the inorganic load amount affects physicochemical characteristics of different silicone compounds. The physicochemical evaluation is performed from several measurements, such as: density, hardness, elongation, tensile strength. In addition, the evaluation of the physicochemical structure is carried out using infrared test and scanning electronic microscopy (SEM). The electrical analysis is performed from the electric tracking wheel and erosion test, in agreement with the recommendation of the International Electrotechnical Commission (IEC). (C) 2014 Elsevier Ltd. All rights reserved.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This work aims to study the structural characteristics of silica gels obtained from the acid hydrolysis of tetraethoxysilane (TEOS) in water solutions with different concentrations of sodium dodecyl sulfate (SDS). The structural characteristics were studied in stages ranging from the wet gel to the dry stages of the gels (aerogels and xerogels). Aerogels were obtained by ambient pressure drying (APD) after silylation process using trimethylchlorosilane (TMCS) as silylating agent. Xerogels were obtained by conventional evaporating the liquid phase from non silylated gels. The samples were characterized by nitrogen adsorption and small angle X-ray scattering (SAXS). The structure of the wet gels and of the aerogels prepared with the surfactant exhibited characteristics of mass-fractal structures with fractal dimension D in the range 2.1-2.2 for the wet gels and 2.3-2.4 for the aerogels. The characteristic size of the fractal domain reduces while the size a0 of the primary silica particle composing the fractal structure increases with the drying of the gels, in a process in which share of the porosity is eliminated. Aerogels exhibited typical values for the specific surface of 900 m2g-1 and of 3.5 cm3.g-1 for the total pore volume. These values are correspondingly comparable to those of the aerogels prepared by supercritical drying, since the silylation process replaces hydrophilic –OH groups by hydrophobic –Si-R3 ones, inhibiting the porosity elimination on drying. The silica particle size also increases lightly with the silylation because the attachment of the –Si-R3 groups on the silica surface. The pore size distribution curves of the aerogels are similar for all samples exhibiting a maximum in around 40 nm, independent the concentration of surfactant. This suggests that the characteristic size of 40 nm is due to the association of surfactant micelles... (Complete abstract click electronic access below)
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In the present work the thermal characteristics of gels and xerogels of Silica/organic hybrids derived from different concentrations of GPTS-TEOS were investigated by thermal analysis (TG, DTA, and DSC). The preparation of gels of the Silica/organic hybrid matrix was held through the sol-gel process, consisting by the hydrolysis of alkoxides GPTS and TEOS in proportion (1:1) and (1:2) that was promoted in acidic conditions under reflux and stirring at 80oC/2h, producing the matrix in the colloidal state (sol). Gels were prepared by addition of NH4OH to the sol, promoting gelation of sol in sealed plastics containers. Part of the gels samples was analyzed by TG, DTS and DSC techniques in order to characterize water loss and degradation of the polymeric “epoxy” groups present in the structure of the silica derived from the GPTS alkoxide. Another set of samples was dried at 80oC/48h to obtain xerogels (dried gels) and analyzed by the same techniques. We obtained the characteristics temperatures of the matrix by the techniques DTA, DSC and TG, under measurements of thermal analysis until 800oC and 600oC in case of DSC. By thermal analysis (TG, DTA, and DSC) the main endothermic events (loss of water, melting, pyrolysis) and exothermic events (burning of the polymer) of the GPTS-TEOS matrix were determined
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Pós-graduação em Bases Gerais da Cirurgia - FMB
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Pós-graduação em Odontologia Restauradora - ICT
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The failure of facial prostheses is caused by limitations in the properties of existing materials, especially flexibility and durability. Therefore, this study evaluated the marginal deterioration of a silicone used for fabrication of facial prostheses (Silastic MDX4-4210, Dow Corning Corporation, Midland, MI, USA) according to the influence of artificial aging, daily disinfection, and 2 types of pigmentation. Thirty specimens were fabricated and subdivided in 6 groups: without pigmentation, pigmented with make-up powder and iron oxide, and evaluated with and without the action of the disinfectant. Analysis of marginal deterioration was performed on a scanning electron microscope (magnification, ×5000) immediately 6 months and 1 year after fabrication of specimens, following the guidelines of ASTM International. After visual analysis of the photomicrographs, it was noticed that all groups presented marginal deterioration and alterations in surface texture with time. The use of disinfection did not contribute to the marginal deterioration of polymer (silicone), regardless of the pigmentation and artificial aging.
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Considering the importance of spatial issues in transport planning, the main objective of this study was to analyze the results obtained from different approaches of spatial regression models. In the case of spatial autocorrelation, spatial dependence patterns should be incorporated in the models, since that dependence may affect the predictive power of these models. The results obtained with the spatial regression models were also compared with the results of a multiple linear regression model that is typically used in trips generation estimations. The findings support the hypothesis that the inclusion of spatial effects in regression models is important, since the best results were obtained with alternative models (spatial regression models or the ones with spatial variables included). This was observed in a case study carried out in the city of Porto Alegre, in the state of Rio Grande do Sul, Brazil, in the stages of specification and calibration of the models, with two distinct datasets.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Highlights • Wildlife Services used GIS and GPS to document and track bait distribution during each bait drop. • GIS and GPS were critical in making this eradication project effective and environmentally safe. • Use of the technologies ensured the coverage necessary for the project's goals.
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Abstract Small-scale coffee producers worldwide remain vulnerable to price fluctuations after the 1999-2003 coffee crisis. One way to increase small-scale farmer economic resilience is to produce a more expensive product, such as quality coffee. There is growing demand in coffee-producing and coffee-importing countries for user-friendly tools that facilitate the marketing of quality coffee. The purpose of this study is to develop a prototypical quality coffee marketing tool in the form of a GIS model that identifies regions for producing quality coffee in a country not usually associated with quality coffee, Honduras. Maps of areas for growing quality coffee were produced with information on climate, soils, topography, areas vulnerable to environmental degradation, the location of current quality coffee farms, and infrastructure. The maps depict suitable coffee-growing land in portions of eight western Honduran departments.