917 resultados para thermo-solvatochromism


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The objective of this study was to evaluate the density, density profile, water swelling and absorption, modulus of elasticity and rupture from static bending, and tensile strength of experimental medium-density fiberboards manufactured using Dendrocalamus giganteus (Munro bamboo). The fiber production was carried out through the chemo-thermo-mechanical pulping process with four different conditions. The panels were made with 10% urea formaldehyde resin based on dry weight of the fibers, 2.5% of a catalyzer (ammonium sulfate) and 2% paraffin. The results indicate that treatments with the highest alkali (NaOH) percentage, time and splinter heating temperature improved the physical properties of the panels. The root-fiber interface was evaluated through scanning electron microscopy in fracture zones, which revealed fibers with thick, inflexible walls. The panels' mechanical properties were affected due to the fiber wall characteristics and interaction with resin. Giant bamboo fiber has potential for MDF production, but other studies should be carried out.

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Objectives: To determine the marginal adaptation of bulk-fill composites in class II MO cavities.Methods: Standardized class II MO cavities with bevelled enamel margins were prepared in 40 extracted human molars. The teeth were randomly assigned to one of the five experimental groups (n = 8). The teeth were restored with two horizontal increments of composite (4 mm and 2 mm thickness). The experimental groups were (1st/2nd increment): Gr. A - Venus Bulk-Fill/Venus Diamond; Gr. B - Tetric EvoCeram BulkFill/Tetric EvoCeram; Gr. C - Surefil SDR/Ceram-X; Gr. D - SonicFill; Gr. E - Ceram-X/Ceram-X (control). After finishing procedures, impressions were made using a polyvinyl siloxane and epoxy resin replicas were obtained. Thermo-mechanical stressing was carried out 24 h after the restorative procedure. All specimens were submitted to 240,000 occlusal loading and simultaneous 600 thermal cycles in water at 5 degrees C and 50 degrees C. After loading, a new set of epoxy resin replicas was obtained. Scanning electron microscopy was carried out at 200x magnification. Results for the marginal adaptation were expressed as percentages of continuity relative to the exposed interface and analyzed by ANOVA and Duncan post hoc test (p < 0.05).Results: In enamel, no significant differences were detected before and after thermo-mechanical loading between groups. In dentine, the worst results were observed in Gr. A.Conclusion: By applying simple layering techniques, bulk-fill materials do not allow better marginal adaptation than a standard composite. Clinical significance: A new class of resin-base composite (bulk-fill) was recently launched on the market. The bulk-fill composites exhibited adequate marginal adaptation and similar to the results of the standard composite. (C) 2014 Elsevier Ltd. All rights reserved.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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It is known that the urban environment modifies the energy balance between the surface and the atmosphere, causing changes in temperature, relative humidity, among other things, opening the way for studies aimed at urban climatology. Based on the theme of urban climate, this research focuses on the city of Assis, located west of São Paulo. The generation of urban climate is a result of various factors, among which stand out: the use and different land use, the thermodynamic properties of buildings, number of buildings in the urban, socioeconomic activities, etc.. In general, this increases the temperature and reducing relative humidity, providing thermal discomfort. The rural environment is used for comparison studies to this theme by presenting different characteristics in relation to the structure, morphology and urban functionality. The main objective of this study is to determine the characteristics of temperature and humidity environments with the habits and occupations of the different soils in winter, at night, one inserted into the urban fabric of Assis and the other in the rural environment, to verify for evidence of changes in climatic elements because of urbanization. To collect the data will be used mini automatic weather stations that record data on temperature and humidity. For analysis of the results will be made between the data obtained in the city and the countryside, developing graphics application using Excel to tabulate the data. It was found that there were differences in the thermo-hygrometric data collection points, showing a specific urban climate in the city of Assis

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This paper was prepared a polymorphic from of curcumin a natural bioactive compound widely used in Indian medicine in the treatment of a range of illnesses. The preparation was the polymorphic crystallization process and solvent mixtures of organic solvents in order to change the dielectric constant of the solution to obtain crystals. The crystal of curcumin has been studied and characterized by absorption spectroscopic in the infrared, X-ray diffraction powder method and by thermo analytical techniques: thermogravimetry and differential therma analysis (TG-DTA) and differential scanning calorimetry (DSC). The DSC of the pure compound (MP=180,19ºC) showed some differences compared the compound crystallized (MP=176.63ºC) in a mixture of solvents thus indicating the phenomenon of polymorphism, and TG-DTA curve of the compound crystallized showed that this was not a solvatomorphic. Finnally the techniques of X-ray diffraction technique FTIR and powder showed a structural change in the compound crystallized, profile-based graphics when compared to the pure compound, which proves that the compound crystallized it is a polymorph

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This paper is about a case study of using solar energy and wind energy in a farm. For this purpose were collected from the property, such as water consumption and amount of residents. So, we estimate how many conventional panels or PET bottle panels and boiler needed to supply the farm with warm water. It also calculates the amount of photovoltaic panels and the main accessories for converting solar energy into electrical energy. For the pumping of water using photovoltaic panels is dismissed and dimensioned to be a watermill

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The concern of the society with regard to the pollution if becomes each bigger and necessary time. This pollution generates damage for who is in contact, as much in economic terms how much in quality of life. The particulate matter is one of the main polluting the air, being the most harmful to human health, fine particles and ultra fine (below 2.5 μm in diameter). With this, this work had as objective to mensurar the pollution of air for material particulado through samplings in an urban center, in a siderurgical industry, a conventional coal bunker and a forest fire. The equipment used for the sampling of particles had been the DataRam4 (model DR 4000) and the Impactador de Andersen, both developed by company THERMO SCIENTIFIC. The first equipment uses a system of nefelometry and the second uses a gravimetrical system of sampling. During the carried through samplings, it can be observed in some cases the difficulty in the breath, badly be and low visibility that this type of pollutant can cause. In most cases the results were disturbing. In industry, conventional coal bunker and in the forest were measured values high concentration for particles smaller diameters. Peak concentrations issued were: 40,000 μg/m³, 182,000 μg/m³ and 400,000 μg/m³ for the industry, conventional coal bunker and forest, respectively. Already in the urban centre were satisfactory results, always staying within the limit allowed by the rules in force so far in the country

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The current world's need for clean and renewable energy sources aligned with the strong Brazilian growth looking to diversify its electric power generation sources, highly dependent on hydropower and petroleum encourages the implementation of technologies that reach this growth with diversity and cleaning. The sun energy source is considered inexhaustible and can meet the demand for energy through thermo solar plants to generate electricity. Several technologies are being studied and developed in the world and they can be used to generate electricity from the solar concentration, but in Brazil its use is still not found commercially. It is therefore essential to understand these technologies and develop knowledge about them so they can be implemented in Brazil. This work brings an overview of the thermo solar generation in Brazil, showing the different technologies and a thermodynamic simulation of one of such technologies considering a hybrid plant with complementary generation biomass, aiming at the generation of 1 MW in the Brazilian Northeast

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In order to study resin distribution and homogeneity of composite laminates manufactured by RTM, it was used CYCOM 890 monolithic toughened epoxy as a matrix with two different configurations of intermediated modulus (IM) carbon fibers: Satin Weave (5HS) and non crimp fabric (NCF). The injection parameters were defined based on Thermo Gravimetric Analysis (TG), Differential Scanning Calorimetry (DSC) and rheological analysis. After processing the material, the resin/fiber impregnation was studied using ultrasonic test, Thermo Gravimetric Analysis, Differential Scanning Calorimetry, Dynamic Mechanical Analysis (DMA) and flexural tests. Therefore, it was able to observe an internal residual stress during the cooling process in both laminates, higher in the composite using NCF fabric due to the lack of symmetry, although a good proportion of fiber/matrix has been verified by the lower values of flexural modulus deviation. The DMA enabled the visualization of glass transition and its association with the inter and intra molecular interaction and movement, in which the NCF composite presented better permeability due to the lowest temperature of glass transition, when compared to the Satin Weave composite

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Lately, the acceptability of fermented dairy beverages has been increased, due to the nutritional benefits, the practical consumption and the low cost of product for the manufacturers, and consequently for final market price to the consumers. During the manufacturing process, these products can be susceptible to microbiological contamination. The present study investigated the contaminant microbiota in fermented dairy beverages produced by small- and medium-sized companies, by means of analyses on moulds and yeasts counting, determination of the Most Probable Number (MPN) of total and thermo tolerant coliforms, Escherichia coli and Salmonella spp. detection, and determination of pH value. In spite of the absence of Salmonella spp., a high counts of yeasts and moulds were found, and E. coli was detected in five samples (16.67 %); and the sample were classified as “products in poor sanitary conditions”, because they showed thermo-tolerant coliforms counting higher than the standard established by the legislation in force. Therefore, quality programs such as Good Manufacturing Practices (GMP) and Hazard Analysis and Critical Control Points (HACCP) should be employed to prevent any contamination risk, in order to provide safe products to consumers.

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Pós-graduação em Engenharia Mecânica - FEG

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National Council for Scientific and Technological Development (CNPq)