Transparent organic-inorganic nanocomposites membranes based on carboxymethylcellulose and synthetic clay

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Morphological characterization by SEM, TEM and AFM of nanoparticles and functional nanocomposites based on natural rubber filled with oxide nanopowders

Nanocomposites were prepared from mixture of different concentrations of ferroelectric nanoparticles in an elastomeric matrix based on the vulcanized natural rubber. The morphological characterization of nanocomposites was carried out using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). The nanocrystalline ferroelectric oxide is potassium strontium niobate (KSN) with stoichiometry KSr2Nb5O15, and was synthesized by the chemical route using a modified polyol method, obtaining particle size and microstrain equal to 20 nm and 0.32, respectively. These ferroelectric nanoparticles were added into the natural rubber in concentrations equal to 1, 3, 5, 10, 20 and 50 phr (parts per hundred of rubber) forming ferroelectric nanocomposites (NR/KSN). Using morphological characterization, we identified the maximum value of surface roughness at low concentrations, in particular, sample with 3 phr of nanoparticles and factors such as encapsulation and uniformity in the distribution of nanoparticles into the natural rubber matrix are investigated and discussed.

Synthesis of Bi-based superconductor by microwave-assisted hydrothermal method

In this work we studied the synthesis of BSCCO-2212 superconducting phase associating a quite similar method developed by Pechini with the microwave-assisted hydrothermal method. To study the influence of the microwaves on the properties of BSCCO system, we synthesized two samples by such method. For one sample we used carbonates and for the other one we used nitrates as chemical reagents. We also produced a reference sample just using carbonates by Pechini's method to compare their morphological and superconducting properties. The structural properties of the samples were analyzed by scanning electron microscopy and X-ray diffraction. The Bi-2212 phase is predominant in all samples and despites the nitrates-like sample has a broader distribution of grain size in comparison with the reference sample, its magnetic behaviour is closer to that presented by the reference one.

Dielectric behaviour of CaCu3Ti4O12-epoxy composites

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Determina����o da mat��ria seca e teores de macronutrientes em folhas de frut��feras usando diferentes m��todos de secagem

O objetivo desse estudo foi avaliar diferentes m��todos de secagem de folhas para tr��s diferentes frut��feras (maracuj��, p��ssego e abacate), com rela����o �� determina����o da mat��ria seca e os teores foliares de macronutrientes. Foram coletadas amostras de folhas rec��m expandida de tr��s culturas, do pomar da fazenda de ensino e pesquisa da FCAV-UNESP, c��mpus de Jaboticabal, no m��s de janeiro de 2010, coletando-se para cada cultura 12 amostras com 25 folhas cada. Os tratamentos constitu��ram-se por dois m��todos de secagem, estufa de circula����o de ar for��ada regulada a uma temperatura de 70°C e o forno microondas (FMO). Avaliou-se a massa da mat��ria seca e os teores foliares de macronutrientes. Os resultados sugerem que os dois m��todos de secagem testados se assemelham na determina����o de mat��ria seca e nos teores foliares de macronutrientes para as culturas an��lisadas, exceto os teores de c��lcio na cultura do p��ssego.

Optical characterization of europium-doped indium hydroxide nanocubes obtained by Microwave-Assisted Hydrothermal method

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Structural, optical, and magnetic properties of NiMoO4 nanorods prepared by microwave sintering

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Bond strength of artificial teeth attached to a microwave-polymerized denture base resin after immersion in disinfectant solutions

To evaluate the bond strength between two types of acrylic resin teeth and a microwave denture base resin after immersion in disinfectant solutions for 180 days. Eighty specimens made of acrylic resin teeth (Biotone and Biotone IPN) attached to a microwave polymerized denture base resin (Nature-Cryl MC) were divided into eight groups (n = 10) according to the treatment (distilled water-control, 2% chlorhexidine digluconate, 1% sodium hypochlorite and sodium perborate solution-Corega Tabs). The shear strength tests (MPa) were carried out using a universal testing machine with a 0.5 mm/min speed. Data analysis was performed using ANOVA and multiple comparison Student-Newman-Keuls post hoc test (�� = 0.05). Biotone IPN showed similar results among the groups (distilled water, 8.25 �� 1.81 MPa; chlorhexidine, 7.81 �� 3.34 MPa; hypochlorite, 7.75 �� 3.72 MPa; and Corega Tabs, 7.58 �� 2.27 MPa, whereas Biotone showed significantly lower shear bond strength values for the groups immersed in Corega Tabs (5.25 �� 3.27 MPa) and chlorhexidine (6.08 �� 2.35 MPa). Soaking the dentures in 1% sodium hypochlorite could be recommended as a disinfectant solution for dentures fabricated with conventional acrylic resin denture teeth and microwave denture base resin. For dentures fabricated with IPN teeth and microwave denture base resin, all the soaking solutions evaluated in this study could be suggested to denture wearers.

Correlative light-electron fractography of interlaminar fracture in a carbon-epoxy composite

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

c ��-Axis resistivity in graphite-AlCl3 as found by CESR measurements

We report the absolute values of the c ��-axis resistivity obtained from conduction electron spin resonance (CESR) experiments at various temperatures for a graphite-AlCl3 stage 2 compound. The agreement with d.c. measurements is quite good. The temperature dependence of the c ��-axis resistivity previously obtained from CESR for graphite-AlCl3 is revised. �� 1990.

An��lise por computa����o gr��fica das altera����es produzidas em pr��teses totais superiores imersas diretamente em ��gua e pela termociclagem

Objectives: This study aimed to assess dimensional changes in acrylic resin base and artificial teeth position after water storage and thermocycling using computer graphics measurements. Methods: Twenty-four waxed replicas were obtained from a previous upper complete denture. For linear measurements, points in cusps tips of left central incisor and second premolars and molars were marked in one of the prostheses with graphite and transferred to the others using an acrylic resin guide. The prostheses were scanned after waxing, polymerization and treatments and the images were exported to ���AutoCad 2002 Today����� software for measurements. Results: There was no statistically significant difference in changes of each segment for each group and between the phases evaluated after polymerization and thermocycling. In groups I and III, the values after polymerization are higher than those after treatment, which suggests shrinkage while the prostheses in group II have expanded. Conclusion: The three groups exhibited artificial teeth movement after tests in comparison to the polymerized prosthesis. The prostheses submitted to water storage in kiln at 36��C during seven days showed different behavior than the other groups.

Morphology and properties of (Ba, Sr, Ca) titanates synthesized by microwave-assisted hydrothermal method

Ba1-xCaxTiO3, Ba1-xSrxTiO3 and Sr1-xCaxTiO3 (x = 0, 0.25, 0.50, 0.75 and 1) nanoparticles were synthesized using the microwave-assisted hydrothermal method. Samples were prepared for 40 minutes at 140��C under a pressure of 3 MPa using an adapted domestic microwave oven. The samples were characterized by X-Ray diffraction (XRD), scanning electron microscopy (FE-SEM), and Raman, photoluminescence (PL) and ultraviolet-visible (UV-Vis) spectroscopies. XRD data show that ceramic powders have crystalline phases associated with a short-range structural disorder. This structural disorder is confirmed by Raman spectral bands indicating multi-phonon processes and the presence of defects or impurities. Such defects account for a broad band in the photoluminescence spectrum in the green light (460 nm) region for all samples. Gap energy variation, obtained from UV-Vis spectra, suggest a non-uniform band structure of these titanates in accordance with the PL results. The morphology of each sample is changed with doping and varies from a spherical to cubic appearance for energy minimization.