Ionizing radiation induced degradation of poly (2-methoxy-5-(2 '-ethyl-hexyloxy)-1,4-phenylene vinylene) in solution

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise psicolinguística e cognitivo-linguística das provas de habilidades metalinguísticas e leitura realizadas em escolares de 2ª a 5ª série

OBJETIVOS: analisar o desempenho de escolares de 2ª a 5ª série do ensino fundamental em provas de habilidades metalinguísticas e leitura segundo critérios psicolinguísticos e cognitivo-linguísticos e verificar similaridade e diferenças entre as análises. MÉTODOS: participaram 120 escolares de 2ª a 5ª série do ensino municipal, de ambos os gêneros, na faixa etária de sete a 12 anos de idade, divididos em 4 grupos de 30 escolares de cada série. Os escolares foram submetidos à aplicação de provas de habilidades metalinguísticas e de leitura. RESULTADOS: houve diferença estatisticamente significante entre os grupos nas habilidades metalinguísticas, nas regras de decodificação de palavras reais e pseudopalavras para todas as variáveis na leitura de palavras reais, com exceção do erro tipo Recusas, com médias superiores para Tentativas de Som Mal Sucedidas e Falha na Aplicação de Regras Ortográficas, indicando que esses tipos de erros foram os de maior ocorrência. Na leitura de pseudopalavras houve diferença estatisticamente significante em Tentativas de Som Mal Sucedidas, indicando que os escolares apresentaram desempenho inferior na decodificação de palavras que exigiram a utilização de informação fonológica. CONCLUSÃO: a adoção de critérios psicolinguísticos ou cognitivo-linguísticos na avaliação da leitura de palavras e pseudopalavras juntamente com a avaliação das habilidades metalinguísticas fornecem subsídios para a compreensão de como o escolar vem processando os complexos princípios do sistema de escrita do português do Brasil, além de dar o suporte necessário à compreensão das dificuldades específicas apresentadas pelos escolares, orientando o profissional fonoaudiólogo em relação aos objetivos precisos no seu atendimento.

V(2)O(5)/TiO(2) catalytic xerogels raman and EPR studies

Raman spectroscopy and Electron Paramagnetic Resonance (EPR) studies were performed on a series of V(2)O(5)/TiO(2) catalysts prepared by a modified sol-gel method in order to identify the vanadium species. Two species of surface vanadium were identified by Raman measurements, monomeric vanadyls and polymeric vanadates. Monomeric vanadyls are characterized by a narrow Raman band at 1030 cm(-1) and polymeric vanadates by two broad bands in the region from 900 to 960 cm(-1) and 770 to 850 cm(-1). The Raman spectra do not exhibit characteristic peaks of crystalline V(2)O(5). These results are in agreement with those of X-ray Diffractometry (XRD) and Fourier Transform Infrared (FT-IR) previously reported (C.B. Rodella et al., J. Sol-Gel Sci. Techn., submitted). At least three families of V(4+) ions were identified by EPR investigations. The analysis of the EPR spectra suggests that isolated V(4+) ions are located in sites with octahedral symmetry substituting for Ti(4+) ions in the rutile structure. Magnetically interacting V(4+) ions are also present as pairs or clusters giving rise to a broad and structureless EPR line. At higher concentration of V(2)O(5), a partial oxidation of V(4+) to V(5+) is apparent from the EPR results.

Surface characterisation of V(2)O(5)/TiO(2) catalytic system

Samples of the V(2)O(5)/TiO(2) system were prepared by the sol-gel method and calcined at different temperatures. Surface species of vanadium, their dispersion, as well as the structural evolution of the system were analysed by XRD, Raman, EPR, and XPS techniques. The results of XRD showed the evolution of TiO(2) from anatase phase to rutile. phase. The Raman spectra for calcination temperatures up to 500 degreesC showed a good dispersion of vanadium over titania in the form of monomeric vanadyl groups (V(4+)) and polymeric vanadates (V(5+)). At least three families of V4+ ions were identified by EPR investigations. Two kinds of isolated V(4+) species are placed in sites of octahedral symmetry, substituting Ti(4+) in the rutile phase. The third is formed by pairs of V(4+) species on the surface of titania. Above 500 degreesC part of superficial V(4+) is inserted into the,matrix of titania and part is oxidized to V(5+). The XPS results showed that the V/Ti ratio rises with increasing calcination temperature, indicating a smaller dispersion of vanadium.

Structural characterization of 0.5PbMg(1/3)Nb(2/3)O(3)-0.5Ba(x)Pb((1-x))TiO(3) powders

The present work reports the effects caused by barium on phase formation, morphology and sintering of lead magnesium niobate-lead titanate (PMN-50PT). Ab initio study of 0.5PbMg(1/3)Nb(2/3)O(3)-0.5Ba(x)Pb((1-x))TiO(3) ceramic powders, with x = 0, 0.20, and 0.40 was proposed, considering that the partial substitution of lead by barium can reestablish the equilibrium of monoclinic-tetragonal phases in the system. It was verified that even for 40 mol% of barium, it was possible to obtain pyrochlore-free PMN-PT powders. The increase of the lattice parameters of PMN-PT doped-powders confirmed dopant incorporation into the perovskite phase. The presence of barium improved the reactivity of the powders, with an average particle size of 120 nm for 40 mol% of barium against 167 mn for the pure sample. Although high barium content (40 mol%) was deleterious for a dense ceramic, contents up to 20 mol% allowed 95% density when sintered at 1100 degrees C for 4 h. (c) 2007 Elsevier Ltd. All rights reserved.

Crystal structure of human purine nucleoside phosphorylase at 2.3 angstrom resolution

Purine nucleoside phosphorylase (PNP) catalyzes the phosphorolysis of the N-ribosidic bonds of purine nucleosides and deoxynucleosides. In human, PNP is the only route for degradation of deoxyguanosine and genetic deficiency of this enzyme leads to profound T-cell mediated immunosuppression. PNP is therefore a target for inhibitor development aiming at T-cell immune response modulation and its low resolution structure has been used for drug design. Here we report the structure of human PNP solved to 2.3 Angstrom resolution using synchrotron radiation and cryocrystallographic techniques. This structure allowed a more precise analysis of the active site, generating a more reliable model for substrate binding. The higher resolution data allowed the identification of water molecules in the active site, which suggests binding partners for potential ligands. Furthermore, the present structure may be used in the new structure-based design of PNP inhibitors. (C) 2003 Published by Elsevier B.V.

Superstrings in graviphoton background and N=1/2+3/2 supersymmetry

Motivated by Ooguri and Vafa, we study superstrings in flat R-4 in a constant self-dual graviphoton background. The supergravity equations of motion are satisfied in this background which deforms the N = 2 d = 4 flat space super-Poincare algebra to another algebra with eight supercharges. A D-brane in this space preserves a quarter of the supercharges; i.e. N = 1/2 supersymmetry is realized linearly, and the remaining N = 3/2 supersymmetry is realized nonlinearly. The theory on the brane can be described as a theory in noncommutative superspace in which the chiral fermionic coordinates theta(alpha) of N = 1 d = 4 superspace are not Grassman variables but satisfy a Clifford algebra.

Search for associated production of charginos and neutralinos in the trilepton final state using 2.3 fb(-1) of data

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for flavor changing neutral currents via quark-gluon couplings in single top quark production using 2.3 fb(-1) of p(p)over-bar collisions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stochastic variational approach applied to 2, 3 and 4 alpha particles

A stochastic variational method is applied to calculate the binding energies and root-mean-square radii of 2, 3 and 4 alpha particles using an S-wave Ali-Bodmer potential. The results agree with other calculations. We discuss the application of the present method to study the universality in weakly-bound three and four-body systems in the context of ultracold atomic traps.

Search for a Vectorlike Quark with Charge 2/3 in t plus Z Events from pp Collisions at root s 7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of precursor solution on the formation of perovskite phase of Pb(Mg-1/Nb-3(2/3))O-3 thin films

Precursor solutions for Pb(Mg1/3Nb2/3)O-3 (PMN) synthesis were obtained by Pechini's method. The influence of the concentration of organic materials on the phase formation has been studied. For this purpose, PMN solutions were prepared with different precursors and were characterized by thermogravimetric and differential thermal analysis. The obtained solutions were deposited onto a Si (100) substrate by dip coating and pre-treated in a hot plate at 300 degreesC for 1 h. The films were annealed at 600, 700, 800 and 900 degreesC for 1 h and characterized by X-ray diffraction. The perovskite phase was formed after annealing at 600 and 700 degreesC when the solution of PMN was prepared with a lower amount of organic material and starting with mobium oxide. By increasing the temperature to 800 or 900 degreesC, only the formation of pyrochlore phase was observed. With the solution prepared from mobium ethoxide, only the presence of pyrochlore phase was observed independently of the annealing temperature. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Aspects of solid state formation and properties of Sn(0.9)Ti(0.1)O(2) system doped with CoO and Nb(2)O(5)

The effect of calcination temperature during the formation of the solid solution Sn(0.9)Ti(0.1)O(2) doped with 1.00 mol % CoO and 0.05 mol % Nb(2)O(5) is presented. The structural characteristics of this system were studied using X-ray diffraction, and the changes in phase formation were analyzed using the Rietveld method. With an increase in calcination temperature, there is increasing miscibility of Ti into the (Ti,Sn)O(2) phase and near 1000 degrees C, and the remaining TiO(2) (anatase) was transformed into the rutile phase. The sintering process, monitored using dilatometry, suggests two mass transport mechanisms, one activated close to 900 degrees C associated with the presence of TiO(2) (anatase) and the second mechanism, occurring between 1200 and 1300 degrees C, is attributed to a faster grain boundary diffusion caused by oxygen vacancies. (C) 2008 International Centre for Diffraction Data.

Antinociceptive profile of 2,3,6-trisubstituted piperidine alkaloids: 3-O-acetyl-spectaline and semi-synthetic derivatives of (-)-spectaline

In early studies, we have reported the antinociceptive profile of (-)-spectaline, a piperidine alkaloid from Cassia spectabilis. The present study describes the synthesis, the antinociceptive and anti-inflammatory activities of a series of 2,3,6-trialkyl-piperidine alkaloids: the natural (-)-3-O-acetyl-spectaline (LASSBio-755) and ten semi-synthetic spectaline derivatives. Structure-activity relationship (SARs) studies were performed. The structures of all synthesized derivatives were confirmed by means of nuclear magnetic resonance. Compounds were evaluated for their analgesic (acetic acid-induced mouse abdominal constrictions, hot-plate test, formalin-induced pain test) and some of them for the anti-inflammatory activities (carrageenan-induced rat paw edema test). The pharmacological results showed that several of the new compounds given orally at a dose of 100 mu mol/kg significantly inhibited the acetic acid-induced abdominal constrictions, but they were less active than (-)-spectaline. LASSBio-755 and LASSBio-776 were the most actives with 37% and 31.7% of inhibition. In the formalin-induced pain only LASSBio-776 was able to inhibit by 34.4% the paw licking response of the inflammatory phase, (-)-spectaline and LASSBio-755 did show any activity. In the carrageenan-induced rat paw edema, only (-)-spectaline exhibited an anti-inflammatory profile, showing an ED(50) value of 56.6 mu mol/kg. Our results suggest different mechanisms of action for the analgesic activity observed for LASSBio-776 (3-O-Bocspectaline), LASSBio-755 (3-O-acetyl-spectaline) and (-)-spectaline (LASSBio-754). The antinociceptive profile of some of the semi-synthetic spectaline derivatives extends our research concerning the chemical and pharmacological optimization of isolated natural products in the search of new drug candidates from brazilian biodiversity.

The absolute configuration of 1-(3 ',4 '-dihydroxycinnamoyl)cyclopentane-2,3-diol from the Amazonian tree Chimarrhis turbinata

An antioxidant, 1-(3',4'-dihydroxycinnamoyl) cyclopentane-2,3-diol [ or ( E)-2,3-dihydroxycyclopentyl-3-(3',4'-dihydroxyphenyl) acrylate ( 1)], and two known trans- and cis-chlorogenic acid methyl esters were isolated from the ethanolic extract of the leaves of Chimarrhis turbinata. The relative configuration of 1 was determined by NMR and by comparison of the circular dichroic spectrum ( CD) with those of the enantiomers of synthetic 3', 4'-dimethoxycinnamoyl analogues. The absolute configuration of one of the synthetic enantiomers was determined using the CD exciton chirality method. This established the structure of naturally occurring 1 as (E)- 2,3-dihydroxycyclopentyl- 3-(3', 4'-dihydroxyphenyl) acrylate.