Spectroscopic characterization of SnO2 gels - Code: CP11

Excitation and dynamic emission spectra of Eu3+ ions were simultaneously used with FTIR and Raman spectroscopy to study the structural evolution during SnO2 sol → gel → xerogel conversion. Results make evident an increase of the surroundings symmetry for the Eu3+ ions dissolved in SnO2 matrix and a decrease of the amount of hydroxo groups (Sn-OH) during drying. These phenomena were associated to the pursuit of the condensation reaction after gelation. © 1994 Kluwer Academic Publishers.

In vivo evaluation of porous titanium implants with biomimetic coating

The osseointegration of porous titanium implants was evaluated in the present work. Implants were fabricated from ASTM grade 2 titanium by a powder metallurgy method. Part of these implants were submitted to chemical and thermal treatment in order to deposit a biomimetic coating, aiming to evaluate its influence on the osseointegration of the implants. The implants were characterized by Scanning Electron Microscopy (SEM), Electron Dispersive X-Ray Spectroscopy (EDS) and Raman Spectroscopy. Three coated and three control (uncoated) implants were surgically inserted into thirty albino rabbits' left and right tibiae, respectively. Tibiae samples were submitted to histological and histomorphometric analyses, utilizing SEM, optical microscopy and mechanical tests. EDS results indicated calcium (Ca) and phosphorous (P) at the surface and Raman spectra exhibited an intense peak, characteristic of hydroxyapatite (HA). Bone neoformation was detected at the bone-implant interface and inside the pores, including the central ones. The mean bone neoformation percentage in the coated implants was statistically higher at 15 days, compared to 30 and 45 days. The mechanical tests showed that coated implants presented higher resistance to displacement, especially after 30 and 45 days.

Dielectric behavior of epoxy/BaTiO3 composites using nanostructured ceramic fibers obtained by electrospinning

Composite materials made of epoxy resin and barium titanate (BT) electrospun nanostructured fibers were prepared. BT fibers were synthesized from a sol based on barium acetate, titanium isopropoxide, and poly(vinyl pyrrolidone). The fibers were heat-treated at different temperatures and characterized by X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy. Mats of BT fibers heat-treated at 800 C were embedded in epoxy resin into suitable molds. The composites were characterized by SEM, and dielectric measurements were performed by means of dielectric spectroscopy. The dielectric permittivity and dielectric modulus of epoxy resin/BT-fiber composites were measured for two types of samples: with the electrodes parallel and perpendicular to the BT fiber layers. Interestingly, composite samples with electrodes perpendicular to the fiber layers and a BT content as low as 2 vol % led to dielectric permittivities three times higher than that of pure epoxy resin. © 2013 American Chemical Society.

Photoelectrochemical properties of FTO/m-BiVO4 electrode in different electrolytes solutions under visible light irradiation

Photoelectrochemical properties of FTO/BiVO4 electrode were investigated in different electrolytic solutions, potassium chloride (KCl) and sodium sulphate (Na2SO4), and under visible light irradiation condition. In order to accomplish that, an FTO/BiVO4 electrode was built by combining the solution combustion synthesis technique with the dip-coating deposition process. The morphology and structure of the BiVO4 electrode were investigated through X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Photoelectrochemical properties were analyzed through chronoamperometry measurements. Results have shown that the FTO/BiVO4 electrode presents higher electroactivity in the electrolyte Na2SO4, leading to better current stabilization, response time, and photoinduced current density, when compared to KCl electrolyte. Besides, this electrode shows excellent performance for methylene blue degradation under visible light irradiation condition. In Na2SO4, the electrode has shown higher degradation rate, 51 %, in contrast to 44 % in KCl, plus higher rate constant, 174 × 10-4 min-1 compared to 150 × 10-4 min-1 in KCl. Results presented in this communication leads to the indication of BiVO4 thin films as alternate materials to use in heterogeneous photoelectrocatalysis, more specifically in decontamination of surface water. © 2013 Springer-Verlag Berlin Heidelberg.

Estudo das variações elétricas em filmes ultrafinos compondo as unidades sensoriais de uma língua eletrônica

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

Efeito do envelhecimento In Vitro na transformação de fase cristalina da Y-TZP: análise topográfica, mecânica e cristalográfica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Membranas condutoras iônicas de celulose bacteriana

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biocompatilibidade in vivo de implantes de titânio submetidos ao processo biomimético

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Monitoramento do processo de densificação de compósitos termoestruturais de carbono reforçado com fibras de carbono por tomografia computadorizada e resistividade elétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Vidros e vitrocerâmicas em sistemas oxifluoretos

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

Compostos luminescentes em matrizes macroporosas de sílica obtidas por tratamento hidrotérmico a partir de vidro pyrex

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

Preparação e caracterização eletroquímica de material catódico do tipo La2/3-xLi3xTiO3 para aplicações em baterias de Lítio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese, caracterização estrutural, espectroscópica e análise do potencial fotocatalítico do aluminato de cobalto e potencial catalítico na preparação do biodiesel

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of calcium on the structural properties of Ba(1-x)Ca (x) TiO3 particles synthesized by complex polymerization method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preparo e caracterização de compósitos polímero/cerâmica com potencial aplicação como sensor multifuncional

Pós-graduação em Química - IQ