Programa de Pós-Graduação em Física - PPGF/ICEN
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2338
O Programa de Pós-Graduação em Física (PPGF) do Instituto de Ciências Exatas e Naturais (ICEN) da Universidade Federal do Pará (UFPA) foi iniciado em março de 2003 em nível de Mestrado. Em março de 2010, foi iniciado o Curso de Doutorado em Física do PPGF/UFPA, consistindo no primeiro curso de Doutorado em Física da Região Amazônica.
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Navegando Programa de Pós-Graduação em Física - PPGF/ICEN por Assunto "Ácido oléico"
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Dissertação Acesso aberto (Open Access) Espectroscopia de Lente Térmica aplicada ao sistema Ácido oléico/Beta Caroteno(Universidade Federal do Pará, 2007) PASSOS, João Paulo Rocha dos; MOREIRA, Sanclayton Geraldo Carneiro; http://lattes.cnpq.br/7312223977002681In this work we present a study in the mixture formed by the beta-carotene diluted in oleic acid in different concentrations being used for that the technique called of Thermal Lens. We tried to vary the different control parameters as: the thickness of the sample, his/her concentration, the potency of the excitation laser, etc. We applied the aberrant model developed by Shen to find the thermal diffusivity, the variation of the refraction index with the temperature (dn/dT), and the magnitude of the sign of thermal lens, in the samples. We verified, with base in the theoretical model presented in the chapter 2, that if the increase of the potency and of the concentration it is very big and it reaches a certain value, parameters as thermal diffusivity start to present distortions in the measured values. We also observed that the mixture BC:AO presents nonlinear absorption, even for small potencies of the excitation laser used. The contributions presented in this work are unpublished and they should contribute to a better understanding of the thermal properties of the system BC:AO or of similar systems as some vegetable oils that are rich in acid oleic and betacarotene.Dissertação Acesso aberto (Open Access) Medidas de não-linearidades utilizando a técnica de varredura-Z aplicada a mistura ácido oleico e beta-caroteno(Universidade Federal do Pará, 2011) SILVA, Kleber José Rosario da; MOREIRA, Sanclayton Geraldo Carneiro; http://lattes.cnpq.br/7312223977002681We use the Z-scan technique to determine the nonlinear optical parameter (nonlinear refraction index) from oleic acid and beta-carotene diluted in oleic acid. The concentrations of the studied mixture were as the following: 0, 5.6, 11.3, 22.5, 30, 45 and 60 μg/ml. The nonlinear refraction index were evaluated considering the experimental data and Sheik-Bahae theory. The pure oleic acid and the solution of oleic acid with beta-carotene (60 μg/ml) presented nonlinear absorption and its coefficient were calculated. We obtain too nonlinear refraction index for some Amazon vegetable oils.Dissertação Acesso aberto (Open Access) Propriedades dielétricas e térmicas das blendas de poliestireno com ácido oléico e poliestireno com betacaroteno(Universidade Federal do Pará, 2008-08-29) BELO, Ezequiel de Andrade; REMÉDIOS, Cláudio Márcio Rocha; http://lattes.cnpq.br/7146076994037490; MOREIRA, Sanclayton Geraldo Carneiro; http://lattes.cnpq.br/7312223977002681The thermal, dielectrics and optics properties of vegetable oils have been studied by Amazonian Materials Physic Group since 1996 in the Department of Physic of UFPA. Recently collaboration with Physical-chemistry of polymer Laboratory in the Chemistry Institute of UnB allowed studying these oils and its components as polymeric blends. In this work, we search to contribute for this study and we explore thermal and dielectric properties as temperature dependence of blends: Polystyrene (PS) modified with Oleic Acid (OA) and polystyrene modified with Beta-Carotene (BC). We performed dielectric constant and thermal diffusivity measurements resorting Capacitance Bridge and photopyroelectric technical, respectively. We estimate moment of dipole for PS/OA blend in the Debye, Onsager and Kirkwood theoretical models and fitting linear regression of experimental data. The results show the phase transition of OA persists in the blend and it is displacement for high temperature.