Navegando por Orientadores "MOREIRA, Sanclayton Geraldo Carneiro"

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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/7312223977002681
In 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 The contributions presented in this work are unpublished and they should contribute to a better understanding of the thermal properties of the system BC:AO or of similar systems as some vegetable oils that are rich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.
Acesso aberto (Open Access)
Medidas de espectroscopia Raman em cristais KDP e Nanotubos de Carbono: implementação da técnica
(Universidade Federal do Pará, 2008-08-29) FERREIRA, Marcel Luiz Rodrigues; REMÉDIOS, Cláudio Márcio Rocha; http://lattes.cnpq.br/7146076994037490; MOREIRA, Sanclayton Geraldo Carneiro; http://lattes.cnpq.br/7312223977002681
Currently, physicist have developed new techniques for characterization materials, mainly in the field of new materials that are being produced from existing materials such as glass, ceramics, polymers, semiconductor and superconductor materials, magnetic materials, etc. In that line, the Group of Physic of materials of Amazon has acquired new techniques for material characterization and this work is the beginning of the implantation of Raman spectroscopy technique. In this work, we used sample of KH2PO4 crystals (KDP) and carbon single wall nanotube (SWNT). The KDP was chosen because their spectra are well-known and their preparation quite simple. The KDP pure or doped is still researched due have a ferroelectric transition and their several applications in laser, sensors, second and third harmonic generation. SWNT was used in this work because are materials of great scientific and technological interest with applications in nanotechnology such as transistor, diode. KDP samples were submitted uniaxial pressure and high temperatures to investigated possible phase transition. Both decomposition and phase transition was observed through Raman spectra of KDP. In the SWNT Raman spectra was identified well known D and G bands. The results support implantation of Raman spectroscopy in the Laboratory of spectroscopy of UFPA.
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/7312223977002681
We 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.
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/7312223977002681
The 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.