Rift to post-rift evolution of a passive continental margin: the Ponta Grossa Arch, SE Brazil

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

Elaboration of boehmite nano-powders by spray-pyrolysis

Boehmite (gamma-AlOOH) synthesis have been investigated using a spray pyrolysis (SP) device starting from a stable sol of Al-tri-sec-butoxide peptized by nitric acid. Free spherical particles from 100 to 500 nm have been elaborated. Particles sub-structure is made of nano-crystalline boehmite with very small average crystallite size (one crystal cell along the b axis). The nano-crystalline boehmite synthesized by SP at low temperature (200 degrees C) is spontaneously dispersible in water without any surface treatment. Boehmite powder may be transformed to transition gamma-alumina by heat post-treatment. Powders of sub-micrometric and spherical gamma-alumina particles may also be synthesized by SP at 700 degrees C. (C) 2008 Elsevier B.V. All rights reserved.

Preparation and characterizations of Ba0.8Ca0.2TiO3 by complex polymerization method (CPM)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho de frangos de corte de 1 a 21 dias de idade alimentados com rações contendo extrato de leveduras e prebiótico e criados em diferentes temperaturas

The performance of broilers reared at different temperatures and fed diet with or without yeast extract and/or prebiotic in the starter phase was evaluated. One thousand, four hundred and forty 1-d male Cobb-500 (R) were reared at different climatic chambers. The diets with or without yeast extract or prebiotic were fed only in the starter phase (1 to 7 days), and from the 8(th) day on all broiler were fed the same commercial diet. It was used a complete randomized experimental design, as a 3 x 2 x 2 factorial arrangement, with 3 rearing temperatures (high 34 +/- 1 degrees C, control 32 +/- 2 degrees C and low 27 +/- 2 degrees C), 2 yeast extract level (with or without) and 2 prebiotic level (with or without). High and low temperatures decreased the performance of brids at 7 and 21 days old. The inclusion of prebiotic in the pre-starter phase increased weight gain of birds under low temperature at 21 days old and the viability until 21 days old. The inclusion of yeast extract increase feed conversion at 21 days old.

Development of a micro-heat exchanger with stacked plates using LTCC technology

A green ceramic tape micro-heat exchanger was developed using Low Temperature Co-fired Ceramics technology (LTCC). The device was designed by using Computational Aided Design software and simulations were made using a Computational Fluid Dynamics package (COMSOL Multiphysics) to evaluate the homogeneity of fluid distribution in the microchannels. Four geometries were proposed and simulated in two and three dimensions to show that geometric details directly affect the distribution of velocity in the micro-heat exchanger channels. The simulation results were quite useful for the design of the microfluidic device. The micro-heat exchanger was then constructed using the LTCC technology and is composed of five thermal exchange plates in cross-flow arrangement and two connecting plates, with all plates stacked to form a device with external dimensions of 26 x 26 x 6 mm(3).

Yellow ZnxNi1-xWO4 pigments obtained using a polymeric precursor method

New tungstate-based ceramic pigments, displaying ZnxNi1-xWO4 stoichiometry, were obtained at low temperature using a polymeric precursor method. The powder precursors were milled in an attritor mill in an alcoholic rnedium and heat treated for 12 h. yielding homogeneous and crystalline powder pigments. Characterization (TG/DTA, XRD, IR and colorimetry) showed that mass loss increased with increasing Zn contents. Despite the presence of secondary phases and impurities, the wolframite phase was present in all samples. IR analysis revealed bands related to Me-O and [WO6](6-) group stretching was observed. The intensity of the yellow color of the pigments increased with increasing amount of nickel. (c) 2007 Elsevier Ltd. All fights reserved.

Energy States of Phosphorous Donor in Silicon in Fields up to 18 T

The evolution of the energy states of the phosphorous donor in silicon with magnetic field has been the subject of previous experimental and theoretical studies to fields of 10 T. We now present experimental optical absorption data to 18 T in combination with theoretical data to the same field. We observe features that are not revealed in the earlier work, including additional interactions and anti-crossings between the different final states. For example, according to the theory, for the "1s -> 2p (+)" transition, there are anti-crossings at about 5, 10, 14, 16, and 18 T. In the experiments, we resolve at least the 5, 10, and 14 T anti-crossings, and our data at 16 and 18 T are consistent with the calculations.

Effect of processing conditions on the nucleation and growth of indium-tin-oxide nanowires made by pulsed laser ablation

Indium-tin oxide nanowires were deposited by excimer laser ablation onto catalyst-free oxidized silicon substrates at a low temperature of 500 degrees C in a nitrogen atmosphere. The nanowires have branches with spheres at the tips, indicating a vapor-liquid-solid (VLS) growth. The deposition time and pressure have a strong influence on the areal density and length of the nanowires. At the earlier stages of growth, lower pressures promote a larger number of nucleation centers. With the increase in deposition time, both the number and length of the wires increase up to an areal density of about 70 wires/mu m(2). After this point all the material arriving at the substrate is used for lengthening the existing wires and their branches. The nanowires present the single-crystalline cubic bixbyite structure of indium oxide, oriented in the [100] direction. These structures have potential applications in electrical and optical nanoscale devices.

Determination of the activation energies of beef tallow and crude glycerin combustion using thermogravimetry

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Microwave Hydrothermal Synthesis and Photocatalytic Performance of ZnO and M:ZnO Nanostructures (M = V, Fe, Co)

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

Indium hydroxide nanocubes and microcubes obtained by microwave-assisted hydrothermal method

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

SiO2-GeO2 soot preform as a core for Eu2O3 nanocoating: Synthesis and photophysical study

Nowadays solid state chemists have the possibility of work with low temperature strategies to obtain solid state materials with appropriate physical and chemical properties for useful technological applications. Photonic core shell materials having a core and shell domains composed by a variety of compounds have been synthesized by different methods. In this work we used silica-germania soot prepared by vapor-phase axial deposition as a core where a nanoshell of Eu2O3 was deposited. A new sol-gel like method was used to obtain the Eu2O3 nanoshell coating the SiO2-GeO2 particles, which was prepared by the polymeric precursor method. The photophysical properties of Eu3+ were used to obtain information about the rare earth surrounding in the SiO2-GeO2@Eu2O3 material during the sintering process. The sintering process was followed by the luminescence spectra of Eu3+ and all the samples present the characteristic emission related to the D-5(0) -> F-7(J) (J=0, 1, 2, 3 and 4). The ratios of the D-5(0) -> F-7(2)/D-5(0) -> F-7(1) emission intensity for the SiO2-GeO2@Eu2O3 systems were calculated and it was observed an increase in its values, indicating a low symmetry around the Eu3+ as the temperature increases.

Formation of beta-nickel hydroxide plate-like structures under mild conditions and their optical properties

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparation and characterization of ceria nanospheres by microwave-hydrothermal method

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

Preparation of CeO2 by a simple microwave-hydrothermal method

Cerium carbonate hydroxide (orthorhombic Ce(OH)CO3) hexagonal-shaped microplates were synthesized by a simple and fast microwave-hydrothermal method at 150 degrees C for 30 min. Cerium nitrate, urea and cetyltrimethylammonium bromide were used as precursors. Ceria (cubic CeO2) rhombus-shape was obtained by a thermal decomposition oxidation process at 500 degrees C for 1 h using as- synthesized Ce(OH)CO3. The products were characterized by X-ray powder diffraction, field-emission scanning electron microscopy, thermogravimetric analysis and Fourier transformed infrared spectroscopy. The use of microwave-hydrothermal method allowed to obtain cerium compounds at low temperature and shorter time compared to other synthesis methods. (C) 2008 Elsevier B.V. All rights reserved.