973 resultados para Raw materials.


Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado em Design e Marketing

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado em Design e Marketing

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado em Engenharia Industrial

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado integrado em Engenharia e Gestão Industrial

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Tese de Doutoramento em Engenharia Química e Biológica (área de conhecimento em Engenharia Enzimática e das Fermentações)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

During the 19th century, the most prominent buildings of the city of Belém were faced entirely with tiles manufactured in Portugal and Germany, which now exhibit distinct degrees of degradation. The Pinho mansion is one of the most important of these buildings and was selected for the investigation of the action of the tropical Amazonian climate on the degradation of the tiles. To achieve this objective, the tiles were mapped for organic and inorganic degradation, and samples were collected for analysis. The minerals were determined by XRD, the chemical composition by classical wet methods and SEM/EDS, and the microorganisms under the microscope. The results show that the German and Portuguese tiles are quite different in their composition. While both ceramic bodies are composed of SiO2 and Al2O3, CaO was found only in the Portuguese tile. The low Na2O and K2O contents indicate the addition of materials to reduce the fusion temperature. SiO2 and PbO are the main constituents of the glaze, with CoO and FeO being added as pigment. The ceramic body of the German tiles is constituted of quartz, mullite, and cristobalite, in contrast with the Portuguese tiles, which are made of quartz, gehlenite, diopside, calcite, and feldspars. The glazes are XRD-amorphous. The chemical and mineralogical differences between the German and Portuguese tiles indicate that they were produced from different raw materials under distinct thermal processes. The most prominent weathering-related modifications are the thin layers (German tiles), oxidation stains, dark stains, the detachment of the tile (Portuguese tiles), loss of the glaze and powdering of the ceramic body (Portuguese tiles) through the establishment of Cyanophyta and Bacillariophyta.. The distinct degradation patterns of the tiles exposed to the tropical Amazon climate are a consequence of their distinct mineralogy and chemistry.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado integrado em Engenharia Mecânica

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado em Engenharia Industrial

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado em Sustentabilidade do Ambiente Construído

Relevância:

60.00% 60.00%

Publicador:

Resumo:

When combined at particular molar fractions, sugars, aminoacids or organic acids a present a high melting point depression, becoming liquids at room temperature. These are called Natural Deep Eutectic Solvents – NADES and are envisaged to play a major role on the chemical engineering processes of the future. Nonetheless, there is a significant lack of knowledge of its fundamental and basic properties, which is hindering their industrial applications. For this reason it is important to extend the knowledge on these systems, boosting their application development [1]. In this work, we have developed and characterized NADES based on choline chloride, organic acids, amino acids and sugars. Their density, thermal behavior, conductivity and polarity were assessed for different compositions. The conductivity was measured from 0 to 40 °C and the temperature effect was well described by the Vogel-Fulcher-Tammann equation. The morphological characterization of the crystallizable materials was done by polarized optical microscopy that provided also evidence of homogeneity/phase separation. Additionally, the rheological and thermodynamic properties of the NADES and the effect of water content were also studied. The results show these systems have Newtonian behavior and present significant viscosity decrease with temperature and water content, due to increase on the molecular mobility. The anhydrous systems present viscosities that range from higher than 1000Pa.s at 20°C to less than 1Pa.s at 70°C. DSC characterization confirms that for water content as high as 1:1:1 molar ratio, the mixture retains its single phase behavior. The results obtained demonstrate that the NADES properties can be finely tunned by careful selection of its constituents. NADES present the necessary properties for use as extraction solvents. They can be prepared from inexpensive raw materials and tailored for the selective extraction of target molecules. The data produced in this work is hereafter importance for the selection of the most promising candidates avoiding a time consuming and expensive trial and error phase providing also data for the development of models able to predict their properties and the mechanisms that allow the formation of the deep eutectic mixtures.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado integrado em Engenharia Civil

Relevância:

60.00% 60.00%

Publicador:

Resumo:

[Excerpt] The growing global demand for new energy sources combined with environmental concerns had motivated the search for alternative fuels, produced from renewable raw materials. During the last decade, ethanol was considered the next generation of biofuels. But more recently, n-butanol gained attention due to its superior fuel properties when compared with ethanol. Although n-butanol is naturally produced by solventogenic bacteria through ABE fermentation, the low productivities obtained with this bioprocess discouraged its use. Thus, most of n-butanol produced nowadays is chemical synthesized via petrochemical routes and its price is extremely sensitive to crude oil’s price. One possible approach to overcome this issue is to express non-native pathways in microbial factories. (...)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The first chapter of this book has an introductory character, which discusses the basics of brewing. This includes not only the essential ingredients of beer, but also the steps in the process that transforms the raw materials (grains, hops) into fermented and maturated beer. Special attention is given to the processes involving an organized action of enzymes, which convert the polymeric macromolecules present in malt (such as proteins and polysaccharides) into simple sugars and amino acids; making them available/assimilable for the yeast during fermentation.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Dissertação de mestrado em Técnicas de Caraterização e Análise Química