163 resultados para Aging of Gels
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Pós-graduação em Educação Sexual - FCLAR
Caracterização física e química da carne de peito de aves de diferentes idades submetida à maturação
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This article intends to inventory the medias that also cover Third Age in Brazil, in view of that all the demographic pointers reveal the accented process of aging of the worldwide population, and therefore of our country. A time that the journalists cannot ignore the changes that occur in the interior of the society, in which it is the main area of performance of the journalism, we want to understand why the Brazilian media still dedicates so little space to this phenomenon of the elderly, in contrast of what occurs in other countries. We ask ourselves, then, if the change in the way of looking at the elderly one would not have to be born inside of the University, through the young who prepare for the exercise of the profession, with citizenship and social concern. In the Course of Journalism of the UNESP/Bauru a group of future journalists is searching this subject, for this they sign this article.
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This article intends to inventory the medias that also cover Third Age in Brazil, in view of that all the demographic pointers reveal the accented process of aging of the world-wide population, and therefore of our country. A time that the journalists cannot ignore the changes that occur in the interior of the society, in which it is the main area of performance of the journalism, we want to understand why the Brazilian media still dedicates so little space to this phenomenon of the elderly, in contrast of what occurs in other countries. We ask ourselves, then, if the change in the way of looking at the elderly one would not have to be born inside of the University, through the young who prepare for the exercise of the profession, with citizenship and social concern.
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This article intends to inventory the medias that also cover Third Age in Brazil, in view of that all the demographic pointers reveal the accented process of aging of the world-wide population, and therefore of our country. A time that the journalists cannot ignore the changes that occur in the interior of the society, in which it is the main area of performance of the journalism, we want to understand why the Brazilian media still dedicates so little space to this phenomenon of the elderly, in contrast of what occurs in other countries. We ask ourselves, then, if the change in the way of looking at the elderly one would not have to be born inside of the University, through the young who prepare for the exercise of the profession, with citizenship and social concern. In the Course of Journalism of the UNESP/Bauru a group of future journalists is searching this subject, for this they sign this article.
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This article intends to inventory the medias that also cover Third Age in Brazil, in view of that all the demographic pointers reveal the accented process of aging of the world-wide population, and therefore of our country. A time that the journalists cannot ignore the changes that occur in the interior of the society, in which it is the main area of performance of the journalism, we want to understand why the Brazilian media still dedicates so little space to this phenomenon of the elderly, in contrast of what occurs in other countries. We ask ourselves, then, if the change in the way of looking at the elderly one would not have to be born inside of the University, through the young who prepare for the exercise of the profession, with citizenship and social concern. In the Course of Journalism of the UNESP/Bauru a group of future journalists is searching this subject, for this they sign this article.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Saúde Coletiva - FMB
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New silica-polypropyleneglycol ormosils (organically modified silicates) with covalent bends between the organic (polymer) and inorganic (silica) phases have been prepared by the sol-gel process. Their structural evolution during sol formation, sol-gel transition, gel aging and drying has been studied in situ by small-angle X-ray scattering (SAXS). The experimental SAXS curves corresponding to sols and gels exhibit features expected from fractal objects. Clusters of size around 55 Angstrom with an initial fractal dimension D = 2.4 are formed in the sol. They are constituted of small primary silica particles chemically crosslinked at the end of the polymer chains. A strong liquid-like spatial correlation between the silica particles develops during drying due to the shrinkage of the polymeric network induced by water and ethanol evaporation. The continuous increase in SAXS intensity during drying, while the interparticle distance remains constant, is a consequence of the progressive growth of the dry fraction of the total volume. After drying, the gel structure consists of a rather compact arrangement of silica particles embedded in the polypropyleneglycol matrix.
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Transparent SnO2 gels were obtained from SnCl4 aqueous solution. The sol formation from tin oxihydroxy peptization in different concentrations and by electrolyte addition in solution was measured. It was verified that the residual presence of chloride ions compromises the colloidal system stability. The sol-gel transition was investigated as a function of the quantity of solid particles in the aqueous environment and of aging time at 60°C by infrared spectroscopy and rheological measurements. The transition from plastic to pseudoplastic flow observed with the increase in loading suggests that a continuous and three-dimensional network formation is closely related to hydrogen bridges and/or hydrogen clusters, culminating in the gel formation. © 1990.
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The structural characteristics of saturated silica sonogels were studied by means of small-angle x-ray scattering (SAXS) and thermogravimetric analysis (TG), after a long time of aging in saturated conditions. The sonogels were obtained by a sol-gel routine from ultrasound stimulated tetramethoxysilane (TMOS) hydrolysis carried out with the initial water/TMOS molar ratio (r) ranging from 2 to 10. The saturated sonogel structure can be described as composed by mass fractal-like aggregates (clusters) of primary silica particles, all imbibed in a liquid phase. The values of the mass fractal dimension (D) of the clusters was found all around 2.5, while the characteristic size of the clusters (ξ) was found generally increasing with r, going from approximately 2.3 nm (r = 2) to 4.5 nm (r = 10). The volume fraction of the clusters was estimated from the SAXS data. The results were compared to the values of weight loss fraction at the inflection point that has been found in the derivative of the TG curve, which should accounts for the instant in which the meniscus of the liquid phase penetrates into the clusters under a rapid evaporation process as in a TG test.
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The present article describes the preparation and characterization A anionic Collagen gels obtained from porcine intestinal submucosa after 72 h of alkaline treatment and in the form of rhamsan composites to develop injectable biomaterials for plastic for construction. All materials were characterized by SDS/polyacrylamide gel electrophoresis, infrared spectroscopy, thermal stability, potentiometric titration, rheological properties, and fluidity tests. Biocompatibility was appraised after the injection of anionic collagen:rhamsan composites at 2.5% in 60 North Folk rabbits. Independently of processing, the Collagen's secondary structure was preserved in all cases, and after 72 h of hydrolysis the Collagen was characterized by a carboxyl group content of 346 :L 9, which, at physiological pH, corresponds to an increase of 106 17 negative charges, in comparison to native Collagen, due to the selective hydrolysis of asparagine and glutamine carboxyamide side chain. Rheological studies of composites at pH 7.4 in concentrations of 2, 4, and 6% (in proportions of 75:1 and 50:1) showed a viscoelastic behavior dependent on the frequency, which is independent of concentration and proportion. In both, the concentration of the storage modulus always predominated over the loss modulus (G' > G and delta < 45 degrees). The results from creep experiments confirmed this behavior and showed that anionic collagen:rhamsan composites at pH 7.4 in the proportion of 50:1 are less elastic and more susceptible to deformation in comparison to gels in the proportion of 75:1, independent of concentration. This was further confirmed by flow experiments, indicating that the necessary force for the extrusion of anionic collagen:rhamsan composites, in comparison to anionic Collagen, was significantly smaller and with a smooth flow. Biocompatibility studies showed that the tissue reaction of anionic collagen:rhamsan composites at 2.5% in the proportion of 75:1 was compatible with the application of these gels in plastic reconstruction. These results suggest that the association of Collagen with rhamsan may be a good alternative in the replacement of glutaraidehyde to stabilize the microfibril assembly of commercial Collagen gel preparations. (c) 2005 Wiley Periodicals, Inc.
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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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Purpose: The purpose of this study was to evaluate the color stability of MDX4-4210 maxillofacial elastomer with opacifier addition submitted to chemical disinfection and accelerated aging.Materials and Methods: Ninety specimens were obtained from Silastic MDX4-4210 silicone. The specimens were divided into three groups (n = 30): Group I: colorless, Group II: barium sulfate opacifier, Group III: titanium dioxide opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was conducted three times a week for 2 months. Afterward, the specimens were submitted to different periods of accelerated aging. Color evaluation was carried out after 60 days (disinfection period) and after 252, 504, and 1008 hours of accelerated aging, using a reflection spectrophotometer. Color alterations were calculated by the CIE L*a*b* system. Data were analyzed by three-way ANOVA and Tukey test (alpha = 0.05).Results: Group II exhibited the lowest color change, whereas Group III the highest (p < 0.05), regardless of the chemical disinfection and accelerated aging periods.Conclusion: Opacifier addition, chemical disinfection, and accelerated aging procedures affected the color stability of the maxillofacial silicone.