Navegando por Palavras-chave "aluminum"

Agora exibindo 1 - 2 de 2
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Polymer Nanocomposites for Hydrogen Storage
    (Amer Inst Physics, 2017) Beatrice, Cesar A. G.; Oliveira, Amanda D.; Passador, Fabio R. [UNIFESP]; Pessan, Luiz A.
    Hydrogen is considered to be a clean, economical and safe renewable energy source that would be ideal to replace fossil fuels, because it is light, highly abundant and its oxidation product (water) is environmentally benign. However, hydrogen is easy to burn (the chemical energy per mass of hydrogen is at least three times larger than that of other chemical fuels), which has the risk of fire and explosion. The problems of transportation and storage restrict the application of hydrogen energy, which has become a key factor in the development and utilization of hydrogen energy. This gas adsorbs at solid surfaces depending on the applied pressure and temperature. For storage purposes in mobile applications, the adsorption of hydrogen has been studied mainly on carbon species, but light and reasonably cheap materials of high surface area should prove to be attractive as well. Porous material is a very promising hydrogen storage material, which stores the gas in the form of molecules at low temperatures and compresses hydrogen into the holes effectively. The purpose of this work was to develop a hybrid porous materials consisting of sulfonated polyetherimide matrix with aluminum nanoparticles and faujasite type zeolite. Dilute solutions were first prepared under stirring at room temperature and the solutions were dried under vacuum. The hybrids were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and hydrogen sorption measurements. The addition of aluminum decreased the glass transition temperature of the hybrids when compared to the sulfonated polymer and the TEM images showed that simply physically mixture occurred between polymer and metallic nanoparticles. Hydrogen sorption tests showed an increase in the amount of hydrogen in the presence of zeolite.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    The renal osteodystrophy pattern in Brazil and Uruguay: An overview
    (Nature Publishing Group, 2003-06-01) Araújo, Sônia Maria Holanda Almeida; Ambrosoni, Pablo; Lobão, Rosélia Ribeiro dos Santos [UNIFESP]; Caorsi, Hena; Moyses, Rosa Maria Affonso; Barreto, Fellype de Carvalho [UNIFESP]; Olaizola, Ines; Cruz, Elisa de Albuquerque Sampaio da; Petraglia, Alicia; Reis, Luciene Machado dos; Duarte, Maria Eugenia; Jorgetti, Vanda; Carvalho, Aluizio Barbosa de [UNIFESP]; Cent Univ Venezuela; Universidade Federal de São Paulo (UNIFESP)
    Background. The prevalence of the types of renal osteodystrophy (ROD) has changed in the last two decades. This study evaluates the prevalence and determining factors of the types of ROD in two countries in South America.Methods. Symptomatic patients who underwent bone biopsies for diagnostic purposes (1985 through 2001) were included in the study. In Brazil, a total of 2340 patients were reviewed, 93.1% on hemodialysis (HD), and 6.9% on continuous ambulatory peritoneal dialysis (CAPD). In Uruguay, 167 patients on hemodialysis were included. Uncalcified bone samples were analyzed in order to diagnose the different types of ROD.Results. Comparing. the 1980s to the 1990s, the prevalence of Brazilian patients with hyperparathyroid bone disease (HP) increased from 32.3% to 44.0%, while Al overload decreased from 61.3% to 42.4%. A logistic regression analysis showed that the main factors associated with HP included female gender, age of less than 40 years, black patients, longer time on dialysis, and absence of Al overload. In Uruguay, HP also increased over time from 31.8% to 70.5% (P < 0.05), while Al overload decreased from 42% to 27% (P < 0.05).Conclusion. A better control of Al overload may lead to a change in histologic pattern, as evidenced by the increasing prevalence of HP.