291 resultados para Physico chemical characterization


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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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The purpose of this study was to characterize and to evaluate the bioactivity potential of experimental root canal sealers (ES) based on Portland cement, epoxy resin with nano- and micro-particles of niobium or zirconium oxide used as radiopacifiers in comparison to AH Plus and MTA Fillapex. Methods Specimens of the sealers (10 mm in diameter × 1 mm thick) were prepared and the radiopacity was evaluated according to ISO 6876 (2012) specifications. Characterization of the sealers was performed under the scanning electron microscope (SEM) immediately after setting and after immersion for 28 days in Hank's balanced salt solution (HBSS). In addition X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were also performed. The pH and calcium ion release were measured after 1, 7, 14, 21 and 28 days after completion of seating using a digital pH meter and an atomic absorption spectrophotometer, respectively. Results The experimental sealers exhibited an average radiopacity of 2.5 mm thickness of aluminum, which was similar to MTA Fillapex (P > 0.05) and inferior to AH Plus (P < 0.05). AH Plus did not show bioactivity. Although the experimental sealers did not exhibit the formation of hydration product, they encouraged the deposition of crystalline spherical structures of calcium deficient phosphate. The highest pH and calcium release values were observed with the experimental sealers (P < 0.01). ES-Nb-micro was the only sealer to present hexagonal shaped crystal deposition. Significance Novel root canal sealers based on a mixture of Portland cement, epoxy resin and radiopacifier exhibited a degree of bioactivity although no evidence of cement hydration was demonstrated on material characterization. The radiopacifier particle size had limited effect on the sealer microstructure and chemical properties.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Mixture modeling methodology was used to investigate interactions of sugar, oligofructose and inulin in papaya nectars as related to sensory liking and chemical characteristics. Mixing sugar and inulin and increasing the sugar proportion raised the liking of flavor and sweetness and the overall acceptability of papaya nectars. Addition of the three components, along with raising the sugar proportion, increased the ash and soluble solids content in papaya nectars. The internal preference mappings showed that all nectars with oligofructose and inulin were as well liked as nectar containing sugar alone, except for some formulations with lower quantities of sugar. Formulations with 6 g/100 g sugar and 6 g/100 g inulin, or with 8 g/100 g sugar, 2 g/100 g inulin and 2 g/100 g oligofructose, can be considered to be the best formulations to produce, with regard to sensory liking and adequacy of chemical parameters, besides all papaya nectars with addition of oligofructose and inulin can potentially be claimed as prebiotic. (C) 2015 Elsevier Ltd. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The present study was carried out in order to evaluate the effect of chlorinated and ozonized water on the physico-chemical characteristics of broccoli, produced under organic and conventional cultivation procedures. Organic and conventional broccolis were subjected to two sanitation treatments, using chlorine and ozone, and were kept under cold storage for seven days. Analyses of pH, titrable acidity, soluble solids and weight loss were performed and the content of Cu, Mn and Zn was determined. In addition, the presence of pesticides was verified. The results show no influence of the cultivation method or the sanitation treatment on sample weight loss. Cultivation methods and sanitizing treatments affected broccoli pH, titratable acidity, and soluble solids during the evaluation period. No differences regarding the metal content on organic and conventional broccoli were observed. Furthermore, the presence of organochlorine compounds, nor other pesticides, was not detected both in organic and conventional vegetables.

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

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O trabalho teve por objetivo avaliar a viabilidade do uso da manipueira, residuo líquido resultante da prensagem da massa ralada de mandioca, como substrato na biossíntese de ácido cítrico por Aspergillus niger. Os meios de manipueira foram comparados nas mesmas condições de temperatura, a meios sintéticos, utilizados tradicionalmente. em se tratando de proposta de um novo substrato, foi estudado o armazenamento do resíduo a temperatura ambiente por 72 horas, e realizada a caracterização físico-química da manipueira e dos meios elaborados com esse substrato. Foi avaliada a produção de ácido cítrico nos meios sintéticos e de manipueira. Verificou-se que a produção de ácido cítrico não diferiu quanto ao meio. Não foi observado crescimento do microrganismo nos meios de manipueira com concentrações acima de 70 mg/l de cianeto. Os resultados obtidos mostraram necessidade de maiores estudos para viabilizar o uso da manipueira como substrato na biossíntese de ácido cítrico por A. niger, principalmente no que diz respeito à liberação enzimática do cianeto.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)