89 resultados para Frequencies of oscillating systems
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This study evaluated the cytotoxicity of experimental adhesive systems (EASs) on odontoblast-like cells. Paper discs (n=132) were impregnated with 10 μL of each EAS-R1, R2, R3, R4, and R5 (in an ascending order of hydrophilicity), followed by photoactivation. R1 and R2 are nonsolvated hydrophobic blends, R3 represents a simplified etch-and-rinse adhesive system, and R4 and R5 represent simplified self-etch adhesive systems. Discs were immersed in Dulbecco's modified Eagle's medium for 24 h to obtain eluates applied on MDPC-23 cell cultures. No material was applied on discs used as control (R0). Cell viability [3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay], total protein (TP) production, alkaline phosphatase (ALP) activity, type of cell death, and degree of monomer conversion Fourier transform infrared (%DC-FTIR) were evaluated. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α=0.05). Considering R0 (control) as having 100% of cell viability, R1, R2, R3, R4, and R5 reduced the metabolic activity of cells by 36.4, 3.1, 0.2, 21.5, and 65.7%, respectively, but only R1 and R5 differed from R0. Comparing with R0, lower TP production was observed for R1, R4, and R5, while ALP activity decreased for R1 and R5. Necrotic cell death was predominant for all EASs, but only R1, R4, and R5 differed from R0. Only R5 presented a different apoptotic cell death ratio from R0. R1 presented the lowest %DC (ca. 37%), whereas R4 and R5 presented the highest (ca. 56%). In conclusion, R2 and R3 were not toxic to the MDPC-23 cells, suggesting that the degree of hydrophilicity or %DC of the EASs alone were not responsible for their cytopathic effects. © 2013 Wiley Periodicals, Inc.
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Quando a área a ser irrigada apresenta um elevado gradiente de declive na direção das linhas de derivação, uma opção de dimensionamento é o uso de tubulações com vários diâmetros para economizar no custo e também para manter a variação de pressão dentro dos limites desejados. O objetivo deste trabalho foi desenvolver um modelo de programação linear para dimensionar sistemas de irrigação por microaspersão com linhas de derivação com mais de um diâmetro e operando em declive, visando a minimização do custo anualizado da rede hidráulica e do custo anual com energia elétrica, além de assegurar que a máxima variação de carga hidráulica na linha será respeitada. Os dados de entrada são: configuração da rede hidráulica do sistema de irrigação, custo de todos os componentes da rede hidráulica e custo da energia. Os dados de saída são: custo anual total, diâmetro da tubulação em cada linha do sistema, carga hidráulica em cada ponto de derivação e altura manométrica total. Para ilustrar a potencialidade do modelo desenvolvido, ele foi aplicado em um pomar de citros no Estado de São Paulo, Brasil. O modelo demonstrou ser eficiente no dimensionamento do sistema de irrigação quanto à obtenção da uniformidade de emissão desejada. O custo anual com bombeamento deve ser considerado no dimensionamento de sistemas de irrigação por microaspersão porque ele gera menores valores de custo anual total quando comparado com a mesma alternativa que não considera aquele custo.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Background. Reduced surface tension of liquids results in higher surface wetting ability and diffusivity by the substrate. Objectives. The objective of this study was to evaluate the influence of the Grander Technology in reducing the surface tension of adhesive systems. Methods. Two adhesive systems (self-etch and total-etch) were modified by physical contact with the Grander system Flexible unit to revitalize water, for 48 h. Surface tension of adhesive systems and water in normal and grander-modified conditions was measured with a goniometer. Results. The results showed a reduction of surface tension for all conditions grander-modified between 3-15%. Conclusions. Grander Technology was effective in reducing the surface tension of the Single Bond and Clearfil SE Bond adhesive systems. Clinical significance. Grander technology was employed to restructure the molecular structure of water-based adhesive systems, which can increase their wetness capacity and therefore ensure a greater diffusibility.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Electric power distribution systems, and particularly those with overhead circuits, operate radially but as the topology of the systems is meshed, therefore a set of circuits needs to be disconnected. In this context the problem of optimal reconfiguration of a distribution system is formulated with the goal of finding a radial topology for the operation of the system. This paper utilizes experimental tests and preliminary theoretical analysis to show that radial topology is one of the worst topologies to use if the goal is to minimize power losses in a power distribution system. For this reason, it is important to initiate a theoretical and practical discussion on whether it is worthwhile to operate a distribution system in a radial form. This topic is becoming increasingly important within the modern operation of electrical systems, which requires them to operate as efficiently as possible, utilizing all available resources to improve and optimize the operation of electric power systems. Experimental tests demonstrate the importance of this issue. (C) 2014 Elsevier Ltd. All rights reserved.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We clarify the structure of the Hilbert space of curved βγ systems defined by a quadratic constraint. The constraint is studied using intrinsic and BRST methods, and their partition functions are shown to agree. The quantum BRST cohomology is non-empty only at ghost numbers 0 and 1, and there is a one-to-one mapping between these two sectors. In the intrinsic description, the ghost number 1 operators correspond to the ones that are not globally defined on the constrained surface. Extension of the results to the pure spinor superstring is discussed in a separate work.