Application times, sources and doses of nitrogen on wheat cultivars under no till in the Cerrado region

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

Evaluation of Cu, Mn, and Se in Vegetables Using Ultrasonic Extraction and GFAAS Quantification

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

Effect of lithium additive on the microstructure and electrical responses of 0.9PMN-0.1PT ceramics

Structural effects of lithium additive on 0.9PMN-0.1PT powders prepared by Ti-modified columbite route were studied. The substitution of Li+ ions for Mg2+ ions in the B-site sub-lattice of 0.9PMN-0.1PT perovskite structure was explained in terms of lead and oxygen vacancies generation originated as consequence of the ionic compensation of negatively charged Li'(Mg) sites. The rise in mass transport as consequence of the increasing of Pb2+ and O2- vacancies produces more agglomerated particles during the powder synthesis and changes the mechanical characteristics between grain and grain boundary of sintered ceramic. The relation between K-m and T-m values, the difference between ionic radii of B cation and the molar volume were used to explain the changes in the relaxor behavior and diffusiveness of phase transition as function of lithium doping, which are corroborated by the results obtained through the ferroelectric characterization.

Spatial-temporal variation of Paralonchurus brasiliensis (Actinopterygii: Sciaenidae) density in relation to some environmental factors on the inner shelf of south-eastern Brazilian coast

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

Antiepileptic effect of acylpolyaminetoxin JSTX-3 on rat hippocampal CA1 neurons in vitro

The Joro spider toxin (JSTX-3), derived from Nephila clavata, has been found to block glutamate excitatory activity. Epilepsy has been studied in vitro, mostly on rat hippocampus, through brain slices techniques. The aim of this study is to verify the effect of the JSTX-3 on the epileptiform activity induced by magnesium-free medium in rat CA1 hippocampal neurons. Experiments were performed on hippocampus slices of control and pilocarpine-treated Wistar rats, prepared and maintained in vitro. Epileptiform activity was induced through omission of magnesium from the artificial cerebrospinal fluid (0-Mg2+ ACSF) superfusate and iontophoretic application of N-methyl-D-aspartate (NMDA). Intracellular recordings were obtained from CA] pyramidal neurons both of control and epileptic rats. Passive membrane properties were analyzed before and after perfusion with the 0-Mg2+ ACSF and the application of toxin JSTX-3. During the ictal-like activity, the toxin JSTX-3 was applied by pressure ejection, abolishing this activity. This effect was completely reversed during the washout period 2. when the slices were formerly perfused with artificial cerebrospinal fluid (ACSF) and again with 0-Mg2+ ACSF. Our results suggest that the toxin JSTX-3 is a potent blocker of induced epileptiform activity. (c) 2005 Elsevier B.V. All rights reserved.

Density and Spatial Distribution of Buffy-tufted-ear Marmosets (Callithrix aurita) in a Continuous Atlantic Forest

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

Bonding Efficacy of New Self-etching, Self-adhesive Dual-curing Resin Cements to Dental Enamel

Purpose: This study evaluated the efficacy of the union between two new self-etching self-adhesive resin cements and enamel using the microtensile bond strength test.Materials and Methods: Buccal enamel of 80 bovine teeth was submitted to finishing and polishing with metallographic paper to a refinement of #600, in order to obtain a 5-mm(2) flat area. Blocks (2 x 4 x 4 mm) of laboratory composite resin were cemented to enamel according to different protocols: (1) untreated enamel + RelyX Unicem cement (RX group); (2) untreated enamel + Bifix SE cement (BF group); (3) enamel acid etching and application of resin adhesive Single Bond + RelyX Unicem (RXA group); (4) enamel acid etching and application of resin adhesive Solobond M + Bifix SE (BFA group). After 7 days of storage in distillated water at 37 degrees C, the blocks were sectioned for obtaining microbar specimens with an adhesive area of 1 mm(2) (n = 120). Specimens were submitted to the microtensile bond strength test at a crosshead speed of 0.5 mm/min. The results (in MPa) were analyzed statistically by ANOVA and Tu key's test.Results: Enamel pre-treatment with phosphoric acid and resin adhesive (27.9 and 30.3 for RXA and BFA groups) significantly improved (p <= 0.05) the adhesion of both cements to enamel compared to the union achieved with as-polished enamel (9.9 and 6.0 for RX and BF).Conclusion: Enamel pre-treatment with acid etching and the application of resin adhesive significantly improved the bond efficacy of both luting agents compared to the union achieved with as-polished enamel.

Structural characterization of phase transition of Al2O3 nanopowders obtained by polymeric precursor method

Nanocrystalline Al(2)O(3)powders have been synthesized by the polymeric precursor method. A study of the evolution of crystalline phases of obtained powders was accomplished through X-ray diffraction, micro-Raman spectroscopy and refinement of the structures through the Rietveld method. The results obtained allow the identification of three steps on the gamma-Al2O3 to alpha-Al2O3 phase transition. The single-phase alpha-Al2O3 Powder was obtained after heat-treatment at 1050 degrees C for 2 h. A study of the morphology of the particles was accomplished through measures of crystallite size, specific surface area and transmission electronic microscopy. The particle size is closely related to gamma-Al2O3 to alpha-Al2O3 phase transition. (c) 2007 Elsevier B.V. All rights reserved.

Theoretical analysis of the structural deformation in Mn-doped BaTiO3

An alternative theoretical method to simulate the structural deformation induced by Mn-doping in BaTiO3 is proposed. The periodic quantum-mechanical method is based on density functional theory at B3LYP level. The structural models were obtained from Rietveld refinement of the undoped and Mn doped BaTiO3 X-ray diffraction data. This modelization gives access to the dopant General effect on the electronic structure. In fact, the influence of the doing element itself on the electronic configuration is barely local: therefore, it is not included in the simulation. The simplicity of the model makes it available for working within a wide range of materials.(C) 2004 Published bv Elsevier B.V.

Comparative electrical behavior at low and high current of SnO(2)- and ZnO-based varistors

The complete I-V characteristics of SnO(2)-based varistors, particularly of the Pianaro system SCNCr consisting in 98.9%SnO(2)+1%CoO+0.05%Nb(2)O(5)+0.05%Cr(2)O(3), all in mol%, have been seldom reported in the literature. A comparative study at low and high currents of the nonohmic behavior of SCNCr- and ZnO-based varistors (modified Matsuoka system) is proposed in this work. The SCNCr system showed higher nonlinearity coefficients in the whole range of measured current. The electrical breakdown field (E(b)) was twice as high for the SCNCr system (5400 V/cm) than for the ZnO varistor (2600 V/cm) due to a smaller average grain size of the former (4.5 mu m) with respect to the latter (8.5 mu m). Nevertheless, we consider that another important factor responsible for the high E(b) in the SCNCr system is the great number of electrically active interfaces (85%) as determined with electrostatic force microscopy (EFM). It was also established that the SCNCr system might be produced in disks of smaller dimensions than that of commercial ZnO-based product, with a 5.0 cm(-1) minimal area-volume (A/V) ratio. The SCNCr reached the saturation current in a short time because of the high resistivity of the grains, which is five times higher than that of the grains in ZnO-based varistors.

Recobrimento de apatitas in vitro sobre titânio: influência do tratamento térmico

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

A Simple and Green Analytical Method for the Determination of Formaldehyde

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sintering of tin oxide and its applications in electronics and processing of high purity optical glasses

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

Estudo do mecanismo de corrosão por pites em água do mar de aços inoxidáveis supermartensíticos microligados com Nb e Ti

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

On Ti-18Si-6B and Ti-7.5Si-22.5B powder alloys prepared by high-energy ball milling and sintering

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