926 resultados para thermal stability
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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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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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Turmeric (Curcuma longa L.), which has been used for long time as a spice, food preservative and coloring agent, is a rich source of beneficial phenolic compounds identified as curcuminoids. These phenolic compounds are known for their antioxidant, anti-inflammatory and antimutagenic properties, among others. On the other hand, they are very susceptible to oxidation, requiring protection against oxygen, light and heat. This protection can be achieved by microencapsulation. In this work, the characteristics and the stability of turmeric oleoresin encapsulated by freeze-drying using mixtures of maltodextrin and gelatin as wall materials were studied. Encapsulated turmeric oleoresin was stored at –20, 25 and 60 °C, in the absence of light, and analyzed over a period of 35 days for curcumin and total phenolic contents and color. Results showed that the samples produced with 26% maltodextrin/0.6% gelatin and 22% maltodextrin/3% gelatin presented good encapsulation efficiencies and solubility. In general, the method of encapsulation employed originated products with satisfactory thermal stability, although the encapsulated materials with a higher proportion of maltodextrin in relation to gelatin had better stabilities, especially at –20 and 25 °C temperatures.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The Polymeric Precursor Method has proved suitable for synthesizing reactive powders using low temperatures of calcination, especially when compared with conventional methods. However, during the thermal decomposition of the polymeric precursor the combustion event can be releases an additional heat that raises the temperature of the sample in several tens of degrees Celsius above the set temperature of the oven. This event may be detrimental to some material types, such as the titanium dioxide semiconductor. This ceramic material has a phase transition at around 600 ° C, which involves the irreversible structural rearrangement, characterized by the phase transition from anatase to rutile TiO2 phase. The control of the calcination step then becomes very important because the efficiency of the photocatalyst is dependent on the amount of anatase phase in the material. Furthermore, use of dopant in the material aims to improve various properties, such as increasing the absorption of radiation and in the time of the excited state, shifting of the absorption edge to the visible region, and increasing of the thermal stability of anatase. In this work, samples of titanium dioxide were synthesized by the Polymeric Precursor Method in order to investigate the effect of Fe (III) doping on the calcination stages. Thermal analysis has demonstrated that the Fe (III) insertion at 1 mol% anticipates the organic decomposition, reducing the combustion event in the final calcination. Furthermore, FTIR-PAS, XRD and SEM results showed that organic matter amount was reduced in the Fe (III)-doped TiO2 sample, which reduced the rutile phase amount and increased the reactivity and crystallinity of the powder samples.
Mechanical, thermal, and barrier properties of methylcellulose/cellulose nanocrystals nanocomposites
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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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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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)