947 resultados para Princípios


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The development of computers and algorithms capable of making increasingly accurate and rapid calculations as well as the theoretic foundation provided by quantum mechanics has turned computer simulation into a valuable research tool. The importance of such a tool is due to its success in describing the physical and chemical properties of materials. One way of modifying the electronic properties of a given material is by applying an electric field. These effects are interesting in nanocones because their stability and geometric structure make them promising candidates for electron emission devices. In our study we calculated the first principles based on the density functional theory as implemented in the SIESTA code. We investigated aluminum nitride (AlN), boron nitride (BN) and carbon (C), subjected to external parallel electric field, perpendicular to their main axis. We discuss stability in terms of formation energy, using the chemical potential approach. We also analyze the electronic properties of these nanocones and show that in some cases the perpendicular electric field provokes a greater gap reduction when compared to the parallel field

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The treatment of animals used in research or in education tests requires proper care, scientific judgment and qualified professionals to understand the needs of the animals and the special requirements of the research, tests, and educational programs. The established guidelines aim the development of knowledge necessary for the improvement of health and wellbeing of humans as well as animals to get precise and accurate results. The techniques should not be performed with inappropriate procedures that cause pain or suffering. Some principles should be considered to have an appropriate animal care and treatment.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Engenharia Elétrica - FEB

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Pós-graduação em Comunicação - FAAC

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Pós-graduação em Educação - IBRC

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Música - IA

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Pós-graduação em Odontologia Preventiva e Social - FOA

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Pós-graduação em Direito - FCHS