Navegando por Palavras-chave "Alumina"

Agora exibindo 1 - 3 de 3
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Biocompatibility of a porous alumina ceramic scaffold coated with hydroxyapatite and bioglass
    (Wiley-Blackwell, 2014-07-01) Kido, Hueliton Wilian; Ribeiro, Daniel Araki [UNIFESP]; Oliveira, Poliani de; Parizotto, Nivaldo Antonio; Camilo, Claudia Cristiane; Fortulan, Carlos Alberto; Marcantonio, Elcio; Silva, Victor Hugo Pereira da [UNIFESP]; Renno, Ana Claudia Muniz [UNIFESP]; Universidade Federal de São Carlos (UFSCar); Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); São Paulo State Univ UNESP
    This study aimed to evaluate the osteointegration and genotoxic potential of a bioactive scaffold, composed of alumina and coated with hydroxyapatite and bioglass, after their implantation in tibias of rats. for this purpose, Wistar rats underwent surgery to induce a tibial bone defect, which was filled with the bioactive scaffolds. Histology analysis (descriptive and morphometry) of the bone tissue and the single-cell gel assay (comet) in multiple organs (blood, liver, and kidney) were used to reach this aim after a period of 30, 60, 90, and 180 days of material implantation. the main findings showed that the incorporation of hydroxyapatite and bioglass in the alumina scaffolds produced a suitable environment for bone ingrowth in the tibial defects and did not demonstrate any genotoxicity in the organs evaluated in all experimental periods. These results clearly indicate that the bioactive scaffolds used in this study present osteogenic potential and still exhibit local and systemic biocompatibility. These findings are promising once they convey important information about the behavior of this novel biomaterial in biological system and highlight its possible clinical application. (C) 2013 Wiley Periodicals, Inc.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Influence of Al2O3 nanoparticles structure immobilized upon glassy-carbon electrode on the electrocatalytic oxidation of phenolic compounds
    (Elsevier Science Sa, 2018) Lima, Ana P.; Souza, Roberta C.; Silva, Murilo N. T.; Goncalves, Rosana F. [UNIFESP]; Nossol, Edson; Richter, Eduardo M.; Lima, Renata C.; Munoz, Rodrigo A. A.
    Electrocatalytic oxidation of catechol (CT), dopamine (DP) and tert-butylhydroquinone (TBHQ) is demonstrated on glassy-carbon electrode (GCE) surfaces modified with alumina nanoparticles of different structures and morphologies. Higher electrochemical activity for the oxidation of CT, DP and TBHQ (peak-to-peak separation reduced from 500 to 50 mV in average) was verified on a GCE polished with alpha-Al2O3 suspension in comparison with the surfaces modified with theta and gamma-Al2O3. This result seems to be correlated with the alumina structure instead of the surface area, as the alpha-Al2O3 presented 10-fold lower surface area than theta and gamma-Al2O3, or particle size. Gold and platinum surfaces were similarly modified with alpha-Al2O3 suspension and the distinguished electrochemistry of the phenolic compounds was not observed on the platinum-modified surfaces, which may indicate effect of the substrate on the immobilization of alumina. High stability of the GCE surface modified with alpha-Al2O3 was attested by continuous amperometric detection of the phenolic compounds under hydrodynamic conditions, and superior analytical sensitivity of the alpha-Al2O3-modified electrode was observed with comparable results to those obtained on GCE modified with multi-walled carbon nanotubes. These results demonstrate that alpha-Al2O3 particles commercially available for electrode polishing can be used to develop highly sensitive, reproducible and stable electrochemical sensors, but also indicate that electrode polishing may generate improved electrochemical responses attributed to "cleaned surfaces". (C) 2018 Elsevier B.V. All rights reserved.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Técnica de sinterização à frio aplicada no processamento de Alumina (Al2O3(s))
    (Universidade Federal de São Paulo, 2021-08-03) Borges, Gustavo da Silva Teixeira [UNIFESP]; Antonelli, Eduardo [UNIFESP]; http://buscatextual.cnpq.br/buscatextual/visualizacv.do;jsessionid=699495DEFD363244B0471795FC75B68D.buscatextual_0
    O TCC aqui elaborado tem como foco o estudo da sintetização de compósitos de Al2O3(s)-NaCl(s) por meio da técnica inovadora de sinterização à frio (CSP). Foi possível a partir desta sinterizar uma amostra do compósito à temperatura de 150 ºC. As amostras foram caracterizadas utilizando as técnicas de difração de raios-X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia de impedância (EI). Foi observado que as amostras em análise obtiveram densidades práticas de 100% (NaCl(s)), 42% (Al2O3(s)) e 80% (Al2O3(s)-NaCl(s)) em relação às densidades cristalográficas esperadas. Além disso, O tamanho de grão foi estimado, utilizando o método dos interceptos, no valor de 66 ± 28 µm. A partir dos resultados obtidos neste projeto, foi possível confirmar que o método aqui utilizado não provém uma sinterização completa de alumina e do compósito Al2O3(s)-NaCl(s), no entanto, provém uma sinterização total de NaCl(s).