High 8722
Mostrando 1-12 de 22 artigos, teses e dissertações.
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1. CaracteriazaÃÃo por difraÃÃo de raios-X e espectroscopia MÃssbauer de nanopartÃculas de SnO2 dopadas com ferro / Characterization by X-ray diffraction and MÃssbauer spectroscopy of SnO2 nanoparticles doped with iron
In this work structural characterization by x-ray diffraction and MÂossbauer spectroscopy of Fe-doped semiconducting oxide SnO2 nanoparticles is reported. The compound under study (Sn1−xFexOy) was prepared by high energy ball milling and proteic sol-gel. The samples prepared by ball milling showed an increase of Fe-doping in the semiconducting matrix
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/11/2010
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2. PROCESSAMENTO, CARACTERIZAÇÃO E ESTUDO DE FENÔMENOS CRÍTICOS NOS SISTEMAS SUPERCONDUTORES (Er,Gd)1−xPrxBa2Cu3O7 / PROCESSAMENTO, CARACTERIZAÇÃO E ESTUDO DE FENÔMENOS CRÍTICOS NOS SISTEMAS SUPERCONDUTORES (Er,Gd)1−xPrxBa2Cu3O7
Neste trabalho foram estudados os efeitos das flutuações térmicas na condutividade elétrica de amostras policristalinas com base nos supercondutores Er1xPrxBa2Cu3O7 e Gd1xPrx Ba2Cu3O7. A quantidade de Pr considerada foi x = 0, 00, 0, 05 e 0, 10. As amostras foram preparadas pela técnica padrão de reação de estado sólido e caracterizadas por microsco
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/11/2010
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3. Effect of nitrogen and calcium on the initial grown of restinga species. / Efeito da adição de nitrogênio e cálcio no crescimento inicial de leguminosas arbóreas de restinga
The Restinga is one type of sand coastal ecosystems that are suffering with high anthropic impact and is important the consideration of any action related to the recovery and conservation of the last remaining areas. For that, is necessary to study the grown and the best conditions for seedling production of species that are native from these ecosystems. In
Publicado em: 2009
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4. DEVELOPMENT OF A CAPILLARY ELECTROPHORESIS SYSTEM WITH CONTACTLESS CONDUCTIVITY DETECTION (C4D) FOR THE SEPARATION OF INORGANIC IONS / DESENVOLVIMENTO DE EQUIPAMENTO DE ELETROFORESE CAPILAR COM DETECÇÃO POR CONDUTIVIDADE SEM CONTATO PARA A SEPARAÇÃO DE ÍONS INORGÂNICOS
This work describes the development and evaluation of a home-made capillary electrophoresis (CE) system based on the capacitively coupled contactless conductivity detection (C4D) for the application in capillary zone electrophoresis (CZE). The C4D detection is based on prototypes previously described in the literature. The equipment constructed has a hydrody
Publicado em: 2009
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5. Estudo de filmes finos de GaAS (1-x) Nx/GaAS por espectroscopia Raman e de Fotoluminescência
The dependence of nitrogen (N) concentration on optical properties in thermally treated and as grown thin films of GaAs1−xNx, with 0, 0144 x 0, 0370, is investigated through Raman spectroscopy and Photoluminescence. Raman spectra exhibits the presence of two GaAs1−xNx characteristic modes. A systematic decrease of the longitudinal optical GaAs-ty
Publicado em: 2008
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6. Produtividade Primária do Biofilme em Cultivos dos Camarões Marinhos Farfantepenaeus paulensis e Litopenaeus vannamei.
The primary production of biolm, or periphyton (a microorganisms community attached to submerged natural or artificial substrates) has been used for a long time as a strategy to improve the water quality and as a complementary food source for raised organisms. In spite of the importance of natural productivity in aquaculture systems less atention is given to
Publicado em: 2008
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7. BIDIMENSIONAL FOUNTAIN CODES FOR ERASURE CHANNELS / CÓDIGOS FONTANAIS BIDIMENSIONAIS PARA CANAIS COM APAGAMENTO
Fountain Codes (LT Codes and Raptor Codes) are a class of codes proposed to efficient and reliably transmit data through Erasure Channels. LT Codes and Raptor Codes are a good approximation to the concept of digital fountain and as such are named as fountain codes. They are said to be rateless codes in the sense that the number of symbols produced by the enc
Publicado em: 2008
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8. Transição ordem-desordem da matéria de vórtices em supercondutores detectada através do terceiro harmônico da suscetibilidade AC
Although a vortex state, in type II superconductors, has been anticipated more than 50 years ago, a great deal of theoretical and experimental efforts has still been done in an attempt to investigate how the dynamics of these structures depends on external excitations and on the inherent properties of the underlying superconducting material, such as inhomoge
Publicado em: 2008
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9. Modelo de regiões ativas em rádio freqüências / Model of active regions at radio frequencies
The goal of this work is to model in 3-D the solar atmosphere over active regions in order to reproduce the emission of these regions at radio frequencies. The model computes the radiative transfer equations for the thermal bremsstrahlung and gyro-resonance emission mechanisms. Because there are no measurements of magnetic fields intensities in the higher so
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 27/06/2007
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10. ESPECIAÇÃO DE COMPOSTOS DE ARSÊNIO EM ÁGUAS E FLUIDOS BIOLÓGICOS EMPREGANDO PRÉ-TRATAMENTO FOTOQUÍMICO E MÉTODOS VOLTAMÉTRICOS / SPECIATION OF ARSENIC COMPOUNDS IN WATER AND BIOLOGICAL FLUIDS BY PHOTOCHEMICAL PRETREATMENT AND VOLTAMMETRIC METHODS
The presence of arsenic as a contaminant in water and biological fluids has been studied in recent years due to the high toxicity of this element. In this work a method for the selective determination of arsenic species was developed, which is based on the determination of As(III) directly in the samples and on the determination of total arsenic after a phot
Publicado em: 2007
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11. Amplificadores Ãpticos, estudos de polarizaÃÃo e geraÃÃo de pulso usando processos paramÃtricos em fibras Ãpticas
The recent telecommunication development can be, to a large extent, attributed to the capacity of transmitting information (video, sound and data) at high transmission rates (Tbits/s) through the optical fiber. The constant advances in the technological development of active and passive devices based on optical fibers have enabled a steady increase in commun
Publicado em: 2007
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12. ANÁLISE DE AMPLITUDES DO DECAIMENTO D+ KS(PI)-(PI)+(PI)+ NO EXPERIMENTO FOCUS / AMPLITUDE ANALYSIS OF THE DECAY D+ K (PI)-(PI)+(PI)+ IN FOCUS EXPERIMENT
This thesis is devoted to the study of the decay D+ KS(pi)− (pi)+(pi)+ with data collected from the FOCUS experiment, at Fermilab. The final state composed of 4 pseudo-scalars can be produced through a number of resonant sub-structures. The purpose of this analysis is to find the contributing intermediate states by measuring their relative strenghts an
Publicado em: 2007