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CeO2 - 10% MOL Gd2O3: efeito da codopagem com X% MOL Sm2O3 (O5 X 52) na microestrutura e na condutividade elétrica
(Universidade Federal de São Carlos, 2011-09-16) Araújo, Huyrá Estevão de; Souza, Dulcina Maria Pinatti Ferreira de; https://lattes.cnpq.br/4100119317525940; https://lattes.cnpq.br/1803384161648735
Fuel cells are the most promising technology for producing clean energy. In particular, the Solid Oxide Fuel Cell (SOFC) stands out among the various types due to high efficiency at high temperatures (800 ~ 1000°C) resulting in high cost for power generation. The operating temperature decreasing allows the use of non expensive materials and increases cell life time. One of the challenges for reducing the operating temperature is to increase the electrical conductivity of electrolytes. In this context, the ceria-based electrolytes are an alternative due to its high ionic conductivity at intermediate temperatures (500 ~ 650 °C). In this work, commercial powder of 10 mol% Gd2O3 doped Ceria was co-dopped with X% Sm2O3 (0
Efeitos do treinamento resistido sobre o estresse oxidativo no fígado de ratas ovariectomizadas
(Universidade Federal de São Carlos, 2011-09-16) Rodrigues, Maria Fernanda Cury; Perez, Sergio Eduardo de Andrade; https://lattes.cnpq.br/9408953831211309; https://lattes.cnpq.br/8239825852579803
Estrogen deficiency is associated with increased oxidative stress (OS), which in turn is involved in the physiopathology of diseases such as fatty liver disease (NAFLD). Resistance training (RT) may reduce the oxidative damage by promoting an up-regulation in the antioxidant defence system. Therefore, this study aimed to assess the effects of RT on OS markers in the liver of ovariectomized rats (Ovx). Adult Sprague-Dawley rats were divided into four groups (n = 8 per group): sham-operated sedentary (Sham-Sed), ovariectomized sedentary (Sed-Ovx), sham-operated resistance training (Sham-Rt) and ovariectomized resistance training (Ovx-Rt). During a 10-week RT period, the animals climbed a 1.1 m vertical ladder with weights attached to their tails; the sessions were performed three times a week, with 4-9 climbs and 8-12 dynamic movements per climb. The OS was measured by levels of reduced glutathione (GSH) and oxidized glutathione (GSSG), the enzymatic activity of catalase (CAT) and superoxide dismutase (SOD), the lipid peroxidation (LP), the concentration of vitamin E and gene expression of glutathione peroxidase (GSH-Px). The estrogen deficiency associated with Ovx decreased in the GSH/GSSG ratio (28%), vitamin E concentration (45%), and gene expression of GSH-Px (49%). Moreover, the training induced negative changes in the hepatic anti-oxidative/oxidative balance, as evidenced by the increased TBARS levels (30%), as well as decreased GSH/GSSG ratio (19%) and vitamin E concentration (35%). These data indicate that the RT program adopted did not reverse the hepatic oxidative damage caused by Ovx; indeed, it increased hepatic OS.
Desenvolvimento de compósitos biodegradáveis a partir de amido termoplástico e fibras vegetais
(Universidade Federal de São Carlos, 2011-09-16) Carmona, Vitor Brait; Mattoso, Luiz Henrique Capparelli; https://lattes.cnpq.br/5839043594908917; https://lattes.cnpq.br/4982149954130302
This project had as main objectives to obtain and to develop new and biodegradable composites from renewable sources using a thermoplastic starch (TPS) matrix reinforced with different amounts of natural fibers, acuri, carandá and gravatá. Initially, these fibers were extracted and characterized, which are still unknown to the scientific community their potential use in composites. The characterization were realized by themorgravimetric analysis (TGA), tensile test, chemical characterization by determination of their main constituents and infrared spectroscopy (FTIR), and morphological and structural analysis by xray diffraction (XRD) and scanning electron microscopy (SEM). The fibers had thermal stabilities similar to each other with their initial temperature of thermal degradation in the range of 250 °C. The fibers show a brittle behavior when subjected to tensile tests, and it were determined elastic moludus and tensile strength in the range of 13 to 50 GPa and 180 to 580 MPa, respectively and, both thermal and mechanical stability are in according to those conventional natural fibers. It was possible to determine the crystallinity index of the fibers by XRD, and SEM images show the fibers surfaces. Four composites formulations were obtained and processed based on four different fibers content (5%, 10%, 15% and 20% w/w), and were evaluated as a function of fiber content water absorption properties, thermal and mechanical stability, and morphological and structural characterization by SEM and XRD. The thermal stability and morphology of TPS homogeneous matrix weren t influenced by the presence of natural fibers, besides the absence of new crystalline structures by XRD. The presence of fibers reduced material water absorption. Mechanical properties such as elastic modulus and tensile strength increased with fiber content, especially at levels above 10% w/w, and the viscosity of the molten also have increased with fiber content. Overall, it was possible to extract and to characterize new natural fibers and use them in a TPS matrix, obtaining new biodegradable composites by conventional processing methods.