954 resultados para MOLECULAR MAGNETIC-MATERIALS
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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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In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40 degrees in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure. (C) 2014 Elsevier B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Objective. The general aim of this article is to describe the state-of-the-art of biocompatibility testing for dental materials, and present new strategies for improving operative dentistry techniques and the biocompatibility of dental materials as they relate to their interaction with the dentin-pulp complex.Methods. The literature was reviewed focusing on articles related to biocompatibilty testing, the dentin-pulp complex and new strategies and materials for operative dentistry. For this purpose, the PubMed database as well as 118 articles published in English from 1939 to 2014 were searched. Data concerning types of biological tests and standardization of in vitro and in vivo protocols employed to evaluate the cytotoxicity and biocompatibility of dental materials were also searched from the US Food and Drug Administration (FDA), International Standards Organization (ISO) and American National Standards Institute (ANSI).Results. While there is an ongoing search for feasible strategies in the molecular approach to direct the repair or regeneration of structures that form the oral tissues, it is necessary for professionals to master the clinical therapies available at present. In turn, these techniques must be applied based on knowledge of the morphological and physiological characteristics of the tissues involved, as well as the physical, mechanical and biologic properties of the biomaterials recommended for each specific situation. Thus, particularly within modern esthetic restorative dentistry, the use of minimally invasive operative techniques associated with the use of dental materials with excellent properties and scientifically proved by means of clinical and laboratory studies must be a routine for dentists. This professional and responsible attitude will certainly result in greater possibility of achieving clinical success, benefiting patients and dentists themselves.Signcance. This article provides a general and critical view of the relations that permeate the interaction between dental materials and the dentin-pulp complex, and establish real possibilities and strategies that favor biocompatibility of the present and new products used in Dentistry, which will certainly benefit clinicians and their patients. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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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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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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Pós-graduação em Patologia - FMB
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Using an effective two-body interaction potential, a molecular dynamics study of the structural properties of amorphous ZrF4 phase is presented. The effective pair potential includes steric repulsion, Coulomb interaction due to charge transfer, and charge-dipole interaction due to the large electronic polarizability of anions. The results for structural correlations, such as pair distribution functions, coordination numbers, and bond angle distributions are presented. Excellent agreement is obtained by comparing experimental X-ray diffraction and the simulated static X-ray structure factor. © 1993.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Superlattices formed of two antagonic characteristics have been broadly studied in literature mainly in order to clarify the effects of proximity and interface interactions. Here, we present a study of superlattice introducing an insulator between each superconducting and ferromagnetic layer. The electrical insulator STO, YBCO and LCMO layer are deposited by PLD method. The samples with STO show more intergrowth surface morphology, which favors the application providing better contacts between the grains. The magnetic measurements indicated higher Tc values and high anisotropy for SLs with STO, which is dependent on the relative thickness of LCMO and YBCO.