1000 resultados para Aristóteles (0384-0322 a.C.)
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Combined tunable WDM converters based on SiC multilayer photonic active filters are analyzed. The operation combines the properties of active long-pass and short-pass wavelength filter sections into a capacitive active band-pass filter. The sensor element is a multilayered heterostructure produced by PE-CVD. The configuration includes two stacked SiC p-i-n structures sandwiched between two transparent contacts. Transfer function characteristics are studied both theoretically and experimentally. Results show that optical bias activated photonic device combines the demultiplexing operation with the simultaneous photodetection and self amplification of an optical signal acting the device as an integrated photonic filter in the visible range. Depending on the wavelength of the external background and irradiation side, the device acts either as a short- or a long-pass band filter or as a band-stop filter. The output waveform presents a nonlinear amplitude-dependent response to the wavelengths of the input channels. A numerical simulation and two building-blocks active circuit is presented and gives insight into the physics of the device.
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The hydrotris(pyrazol-1-yl)methane iron(II) complex [FeCl2{eta(3)-HC(pz)(3)}] (Fe, pz = pyrazol-1-yl) immobilized on commercial (MOR) or desilicated (MOR-D) zeolite, catalyses the oxidation of cyclohexane with hydrogen peroxide to cyclohexanol and cyclohexanone, under mild conditions. MOR-D/Fe (desilicated zeolite supported [FeCl2{eta(3)-HC(pz)(3)}] complex) provides an outstanding catalytic activity (TON up to 2.90 x 10(3)) with the concomitant overall yield of 38%, and can be easy recovered and reused. The MOR or MOR-D supported hydrotris(pyrazol-1-yl)methane iron(II) complex (MOR/Fe and MOR-D/Fe, respectively) was characterized by X-ray powder diffraction, ICP-AES, and TEM studies as well as by IR spectroscopy and N-2 adsorption at -196 degrees C. The catalytic operational conditions (e.g., reaction time, type and amount of oxidant, presence of acid and type of solvent) were optimized. (C) 2013 Elsevier B.V. All rights reserved.
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Although global biodiversity is declining, local ecosystems are not systematically losing diversity, but rather experiencing rapid turnover in species.
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Pós-graduação em Pesquisa e Desenvolvimento (Biotecnologia Médica) - FMB
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Gold(III) complexes of type [AuCl2{eta(2)-RC(R'pz)(3)}]Cl [R = R' = H (1), R = CH2OH, R' = H (2) and R = H, R' = 3,5-Me-2(3), pz = pyrazol-1-yl] were supported on carbon materials (activated carbon, carbon xerogel and carbon nanotubes) and used for the oxidation of cyclohexane to cyclohexanol and cyclohexanone, with aqueous H2O2, under mild conditions.
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New studies are giving ecologists some hope of controlling red lionfish, a voracious predator that has invaded the Atlantic.
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This work reports on the optoelectronic properties and device application of hydrogenated amorphous silicon carbide (a-Si(1-x)C(x):H) films grown by plasma-enhanced chemical vapour deposition (PECVD). The films with an optical bandgap ranging from about 1.8 to 2.0 eV were deposited in hydrogen diluted silane-methane plasma by varying the radio frequency power. Several n-i-p structures with an intrinsic a-Si(1-x)C(x):H layer of different optical gaps were also fabricated. The optimized devices exhibited a diode ideality factor of 1.4-1.8, and a leakage current of 190-470 pA/cm(2) at -5 V. The density of deep defect states in a-Si(1-x)C(x):H was estimated from the transient dark current measurements and correlated with the optical bandgap and carbon content. Urbach energies for the valence band tail were also determined by analyzing the spectral response within sub-bandgap energy range. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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OBJETIVO: Avaliar a prevalência do vírus da hepatite entre profissionais da área da saúde e analisar fatores de risco. MÉTODOS: O estudo foi realizado em hospital universitário no município de São José do Rio Preto, SP, de janeiro 1994 a dezembro 1999. Participaram do estudo 1.433 profissionais da área da saúde, 872 funcionários da área administrativa e 2.583 candidatos a doador de sangue. Os dados foram coletados durante exames admissionais, periódicos e após acidentes de trabalho. Informações ocupacionais e não-ocupacionais foram obtidas por meio de questionário. Foram utilizados os testes qui-quadrado, Kruskal-Wallis e análise por regressão logística. RESULTADOS: A prevalência do vírus da hepatite entre os profissionais da saúde (1,7%) foi significativamente maior que nos funcionários administrativos (0,5%; p=0,007) e em candidatos a doadores (0,2%; p=0,001). Entre fatores ocupacionais, o tempo de serviço dos profissionais da saúde com sorologia positiva foi significativamente maior (p=0,016) que naqueles com sorologia negativa. A análise de regressão múltipla revelou que a cada cinco anos na idade, o risco aumenta em 50%. Houve associação significativa entre transfusão de sangue e profissionais de saúde com sorologia positiva. CONCLUSÕES: Profissionais da saúde apresentaram maior prevalência de vírus da hepatite que os profissionais administrativos e candidatos a doador. Naqueles com sorologia positiva, fatores ocupacionais e não-ocupacionais de maior risco foram idade, tempo de serviço e transfusão de sangue.
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Objective - The study evaluated the effect of a canned sardine supplement in C-reactive protein (CRP) in patients on hemodialysis (HD) and the compliance and adherence to this supplement. Design - This was a quasi-experimental study: Participants with a serum CRP of 5 mg/dL or less volunteered to consume a sardine supplement or were maintained on the usual cheese/ham sandwich supplement. Setting - The study took place in two outpatient dialysis units in Lisbon, Portugal. Patients - The study comprised 63 patients receiving maintenance HD three times per week for at least 6 months and an initial CRP concentration of 5 mg/dL or less. Exclusion criteria included the presence of graft vascular access or history of cancer. Intervention - After a 4-week washout period, the nutritional intervention included a canned sardine sandwich for the case group (n = 31) and a cheese or ham sandwich for the control group (n = 32), to be ingested during each routine HD session, 3 times per week, for 8 weeks. Main outcome measure - Serum levels of high-sensitivity CRP were the outcome measure. Results - Only 65 patients from the invited 186 patients met the inclusion criteria and agreed to eat the sardine sandwich supplement three times per week and were involved in the study. A significant proportion of 48% (n = 31, case group) consumed the sardine sandwich supplement three times per week for 8 weeks, fulfilling the requirements and completing the study. The present investigation showed that a sardine sandwich supplement had no effect on CRP levels among patients on HD. However, when participants were stratified according to tertiles of CRP distribution values at baseline, a reduction in CRP levels was found for those in the higher tertile, being higher for the case group (P = .047). Although diabetic patients were excluded from the analysis (eight in the sardine supplementation group and seven in the control group) a significant CRP reduction was found (P = .034). Conclusion - Although a supplement of low-dose n-3 long-chain polyunsaturated fatty acids had no effect on the plasma high-sensitivity CRP of the supplemented group, a reduction in CRP levels was found when patients were stratified for tertiles of CRP (for the upper tertile) and diabetic status (for nondiabetic patients). These findings need to be further confirmed. This canned sardine supplement was accepted by an important proportion of patients, enhancing diet variety and contributing for a greater n-3 long-chain polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid intake.
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Dissertação de Mestrado em Biodiversidade e Biotecnologia Vegetal
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Dissertação de Mestrado em Biodiversidade e Biotecnologia Vegetal
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O presente texto corresponde ao capítulo XIII do livro em apreço, redigido em co-autoria com colegas da Universidade dos Açores, no qual se apresentam alguns dos resultados do estudo realizado em torno da cultura do brincar nos Açores.
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Artigo traduzido para mandarim, publicado em Nature and Human Life E-Academic Magazine, 6 (2015), pp. 19-32. http://www.ziranyurensheng.org/current-2961621002.html.