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Search Results: 1 - 10 of 201145 matches for " Oliveira Ant?nio Pedro Novaes de "
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Desenvolvimento de porcelana quartzosa para isoladores elétricos de alta tens o
Alan Neves Bonetti,Jony C. Tomelin,Orestes Estevam Alarcon,Antnio Pedro Novaes de Oliveira
Exacta , 2009,
Abstract: The fabrication technology of high-voltage ceramic insulators was traditionally developed by using quartz-based porcelain compositions. The objective of this work was to develop an IEC 672 C 110 quartz-based ceramic body for high-voltage insulators according to IEC 672 C 120. Thus, a reference industrial formulation was compared with two alternative formulations, which show higher alumina and lower free quartz contents. The milling step was also optimized related to time and residue. The raw materials were characterized by XRF and XRD. Ceramic bodies were characterized by laser diffraction and, after firing process, by XRD and SEM. The sintered samples show mechanical strength of about 70 MPa for the standard ceramic body and 100-110 MPa for the alternative ones. The quartz-based ceramic bodies (IEC 672 C 110) developed are in good agreement with the IEC 672 C 120 international standard.
Processing and Characterization of Yttria-Stabilized Zirconia Foams for High-Temperature Applications
Ana María Herrera,Amir Antnio Martins de Oliveira Jr.,Antonio Pedro Novaes de Oliveira,Dachamir Hotza
Journal of Ceramics , 2013, DOI: 10.1155/2013/785210
Abstract: In this work ceramic foams of 3 and 8 mol% yttria-stabilized zirconia (3YSZ and 8YSZ) were manufactured by the replication method using polystyrene-polyurethane foams with pore sizes in the 7–10 ppi range. A second coating was carried out on presintered foams in order to thicken struts and hinder microstructural defects. The produced ceramic foams were structurally and thermomechanically characterized. Samples recoated with 3YSZ presented the highest relative densities ( ) which contributed to a better mechanical and thermal behavior. 1. Introduction Porous radiant burners are devices used in applications benefit from radiant thermal heating. Numerous industries employ this technology for firing and drying, lower pollutant emission, and better product quality reached with these burners [1, 2]. Other functional advantages are a higher flame velocity within the porous structure when compared to a laminar free flame (due to the preheated of reagents), higher turn-down ration, higher efficiency in heat transfer by radiation, and the possibility of burning low calorific value fuels or very lean mixtures [3]. Ceramics foams for porous radiant burners are mainly produced by the replication method from polymeric templates. The method consists in the impregnation of a polymeric sponge with a ceramic slurry followed by a heat treatment which leads to the burning out of the organic body (sponge) and to the sintering of the ceramic skeleton [4]. Along the manufacture process, there are key parameters that must be taken into account to ensure the final product effectiveness. Among them, the most important are the linear expansion coefficient, maximum working temperature and thermal shock resistance of the ceramic material, thixotropy and pseudoplasticity of the ceramic slurry, and, finally, the heating rate of the thermal treatment. According to the above, the most reliable ceramic materials to work with are cordierite, mullite, silicon carbide, alumina, partially stabilized zirconia (YSZ), and some composite systems [5–13]. Cellular ceramics are already commercially available for a wide range of technological applications including filters, membranes, catalytic substrates, thermal insulation, gas burner media, refractory materials, and lightweight structural panels [5–7]. In these cases, reticulated porous ceramics are used because of their functional properties, such as low thermal expansion coefficient and thermal conductivity, high permeability, and chemical inertness [7]. Considering the particularities associated with each specific application, reticulated
Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses
Silveira, Cristian Berto da;Campos, Sílvia Denofre de;Campos, Elvio A. de;Oliveira, Antnio Pedro Novaes de;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000100004
Abstract: differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of bao on the crystallization mechanism of li2o-zro2-sio2 systems. as the concentration of bao in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. to determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % bao, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. the first nuclei appeared at the first endothermic inflection point (at the start of tg, at 440 °c), while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °c). these results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.
Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses
Silveira Cristian Berto da,Campos Sílvia Denofre de,Campos Elvio A. de,Oliveira Antnio Pedro Novaes de
Materials Research , 2002,
Abstract: Differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of BaO on the crystallization mechanism of Li2O-ZrO2-SiO2 systems. As the concentration of BaO in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. To determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % BaO, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. The first nuclei appeared at the first endothermic inflection point (at the start of Tg, at 440 °C), while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °C). These results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.
Decomposi??o térmica de espumas de poliuretano para fabrica??o de vitroceramica celular de Li2O-ZrO2-SiO2-Al2O3 (LZSA)
Silveira, Cristian Berto da;Escobar, Jairo A.;Quintero, Miguel W.;Sousa, Eliandra de;Moraes, Elisangela Guzzi de;Oliveira, Antnio Pedro Novaes de;Rambo, Carlos Renato;Hotza, Dachamir;
Química Nova , 2007, DOI: 10.1590/S0100-40422007000500010
Abstract: characterization of the thermal decomposition of polyurethane (pur) foams was performed by fourier-transformed infrared (ft-ir) spectroscopy and thermogravimetric analysis (tga). three main weight loss paths were observed by tga, the residue being lower than 3 wt.% for 3 different pur foams analyzed. ft-ir spectra indicated co2, co, nh3 and isocyanides as main decomposition products. pur foams of different cell sizes were immersed in a slurry of the parent glass ceramic of composition li2o-zro2-sio2-al 2o3 (lzsa) and submitted to heat treatment. the lzsa cellular glass ceramics obtained after sintering and crystallization resembled the original morphology of the pur foams.
Utilidades e limita es do uso de diretrizes no tratamento da depress o
Oliveira Irismar Reis de,Lima Pedro Antnio Prado
Revista Brasileira de Psiquiatria , 2003,
Abstract:
Tomografia computadorizada na análise dos padr?es de calcifica??es nos tumores ósseos da bacia em pediatria: nova abordagem
Oliveira, Gabriel Antnio de;Werlang, Henrique Zambenedetti;Bergoli, Pedro Martins;Frechiani, Madalena;Oliveira, Fern?o;
Radiologia Brasileira , 2006, DOI: 10.1590/S0100-39842006000600008
Abstract: objective: in the pediatric group, the radiological diagnosis of bone tumors of the hip is difficult and presents some peculiarities, but reviewed literature does not approach this specific problem. the objective of the present study was to investigate the existence of reliable radiological patterns for the differential diagnosis of these tumors. materials and methods: radiological findings of bone tumors of the hip in ten patients in the age range between 8 and 19 years have been reviewed. results: bone reaction (sclerosis or lysis), periosteal reaction (lamellar with single or multiple layers, or radial), tumor extent in the bone and level of soft tissues invasion have presented low specificity. soft tissue calcifications, when considered as a whole, were non-specific. however, when those calcifications with varied shapes and sizes, nearby the affected bone (pattern i) were separated from those, thin and amorphous, away from the bone (pattern ii), we have observed that the pattern i was totally non-specific, and the pattern ii was found in the three cases of osteosarcoma (100%) and in only one case of ewing's sarcoma (16.6%). conclusion: in the present study, pattern ii calcifications have shown a 100% sensitivity and 90% specificity for osteosarcoma. however, their importance may be not limited to the radiological diagnosis. pattern ii calcifications indicate probably ideal sites for biopsy.
Dan a e desenvolvimento motor de portadores de necessidades educativas especiais - PNEEs
Liliane de Oliveira,Rubiane Falkenberg Zancan,Marilia de Rosso Krug,Pedro Antnio Batistella
Revista Educa??o Especial , 2002,
Abstract: O estudo objetivou verificar as modifica es nos padr es de desenvolvimento motor de PNEEs mediante prática da dan a. Participaram 14 PNEEs do CIEP/Cruz Alta. O instrumento foi a Escala de Desenvolvimento Motor (Rosa Neto, 1996). Utilizou-se a estatística descritiva e teste “t” para análise dos dados. Observou-se diferen as estatisticamente significativas (p<0,05) entre pré e pós-testes nas variáveis idade cronológica, motora geral, motricidade ampla e equilíbrio. Concluiu-se que o programa de dan a contribuiu significativamente para o desenvolvimento motor de PNEEs. Palavras chave: dan a, motor, desenvolvimento, especial, educa o.
Vasculopatia livedóide: relato de caso com possível evidência de etiopatogenia neurovascular
Kalil-Gaspar, Neide;Kurizky, Patricia Shu;Gaspar, Antnio Pedro A.;Oliveira, Joelma Maria de;
Anais Brasileiros de Dermatologia , 2007, DOI: 10.1590/S0365-05962007000400008
Abstract: etiopathogenesis of livedoid vasculopathy remains elusive, and this condition is still frequently designated as idiopathic or secondary to various disorders. while several etiologies have been proposed, neither are they always associated with the disease, nor do they necessarily include livedoid vasculopathy in their course. moreover, treatments described in the literature do not present reproducible results. we present the case of a 42-year-old man with livedoid vasculopathy who presented a good response to treatment with carbamazepine, a previously unattempted approach. in view of the very scarce evidence for vascular inflammation, discrepancies in the proposed etiologies of this pathological state and the intense pain that is the hallmark symptom; and considering recent reports on the neural participation in coagulation processes, the authors here address the question of a potential association between the vascular and nervous systems in the etiology of this vasculopathy.
Efeito do azul de metileno na resposta inflamatória e hemodinamica em pacientes submetidos à cirurgia de revasculariza??o miocárdica com circula??o extracorpórea
Ribeiro, Nilzo Augusto Mendes;Stolf, Noedir Antnio Groppo;Silva Junior, Augusto Ferreira da;Viana, Valcellos José da Cruz;Carvalho, Eduardo Novaes de;Athanázio, Rodrigo;Reis, Mitermayer Galv?o;Oliveira, Sérgio Almeida de;
Revista Brasileira de Cirurgia Cardiovascular , 2004, DOI: 10.1590/S0102-76382004000100005
Abstract: objective: to assess the effects of methylene blue infusion on on-pump coronary artery bypass patients in relation to hemodynamic, laboratorial and systemic inflammatory response. method: sixty patients were randomized in two groups. methylene blue was infused in one group. blood samples were collected before the anesthesia and, 3, 6, 24 and 48 hours after the end of the extracoporeal circulation to determine the il-1b, il-6, il-8, il-10, il-12p40, tnfa and nitric oxide levels and perform gasometry and other routine tests. results: in the methylene group we observed at different stages, higher systemic vascular resistance, lower tnfa concentrations, fewer leukocytes and neutrophils as well as lower level of nitric oxide. no adverse effects were evidenced. conclusions: methylene blue infusion showed less tendency of systemic inflammatory responses, lower levels of nitric oxide and a better hemodynamic performance.
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