Spin-orbit coupling in the superconducting phase and DDW states of high-T-c cuprates

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Schrodinger and Pauli-Dirac Oscillators in Noncommutative Phase Space

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Memory effect and fast spinodal decomposition

We consider the modification of the Cahn-Hilliard equation when a time delay process through a memory function is taken into account. We then study the process of spinodal decomposition in fast phase transitions associated with a conserved order parameter. The introduced memory effect plays an important role to obtain a finite group velocity. Then, we discuss the constraint for the parameters to satisfy causality. The memory effect is seen to affect the dynamics of phase transition at short times and have the effect of delaying, in a significant way, the process of rapid growth of the order parameter that follows a quench into the spinodal region.

THE EFFECT of WEAK DISSIPATION IN TWO-DIMENSIONAL MAPPING

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of robust torus on the dynamical transport

In the present work, we quantify the fraction of trajectories that reach a specific region of the phase space when we vary a control parameter using two symplectic maps: one non-twist and another one twist. The two maps were studied with and without a robust torus. We compare the obtained patterns and we identify the effect of the robust torus on the dynamical transport. We show that the effect of meandering-like barriers loses importance in blocking the radial transport when the robust torus is present.

Effect of partial crystallization on the mechanical properties and cytotoxicity of bioactive glass from the 3CaO center dot P2O5-SiO2-MgO system

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

Effect of the excess of bismuth on the morphology and properties of the BaBi2Nb2O9 thin films

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

Effect of magnesium on structure and properties of LiNbO3 prepared from polymeric precursors

The effect of magnesium addition on the phase formation and electric properties of LiNbO3 powder prepared from polymeric precursor was analyzed. It was shown that the unit-cell volume of the rhombohedral phase decreased with increasing magnesium concentration. Small amounts of secondary phases were observed in LiNbO3 powder doped with 5 and 10 mol% Mg+2. These results indicated that the Mg+2 ion was substituted for niobium ion in the rhombohedral phase. The addition of Mg+2 promotes densification of LiNbO3 ceramics. It was noticed that the increase in additive concentration leads to a decrease of electric properties, K-p and d(33). This is due to formation of LiNb3O8 and MgNb2O6 phases at the grain boundaries. (C) 2002 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.

Effect of 4 mass% Ag addition on the thermal behavior of the Cu-9 mass% Al alloy

The effect of 4 mass% Ag addition on the thermal behavior of the Cu-9 mass% Al alloy was studied using differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The results showed that the presence of silver causes (Cu)-alpha+(alpha+gamma1)-->(Cu)-alpha+beta transformation to occur in two stages. In the first one, part of the produced beta phase combines with the precipitated Ag to give a silver-rich phase and in the second one the transformation is completed. The formation of this silver-rich phase seems to be enhanced at very low cooling rates.

Effect of Ag additions on the reverse martensitic transformation in the Cu-10 mass% Al alloy

The effect of Ag additions on the reverse martensitic transformation in the Cu-10 mass% Al alloy was studied using differential thermal analysis (DTA), optical (OM) and scanning electron microscopies (SEM) and X-ray diffractometry. The results indicated that Ag additions to the Cu-10 mass% Al alloy shift the equilibrium concentration to higher Al contents, allow to obtain both beta(1)' and beta' martensitic phases in equilibrium and that Ag precipitation is a process associated with the perlitic phase formation.

Effect of welding on the microstructure and electrochemical corrosion of Al-Zn-Mg-Fe alloys

The effect of gas tungsten are welding on the microstructure and electrochemical corrosion of Al-Zn-Mg-Fe alloys submitted to different heat treatments (as fabricated, annealed and aged) has been studied using optical microscopy, SEM, TEM, EDX, cyclic voltammetry and corrosion potential measurements in chloride solutions. The electrochemical techniques were very sensitive to the change in the phase compositions produced by welding. Welding caused a decrease in the mean grain size, in the hardness and in the corrosion resistance of the age-hardened alloys. The structure of the latter became strongly altered by welding to lead to phase compositions very close to those of the cold rolled and annealed specimens. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

The effect of preparation method and Sb content on SnO2-CuO sintering

The sintering behavior of SnO2-CuO system has been investigated for two preparation methods and as a function of antimony concentration. A chemical preparation (Pechini's method) resulted in powders with smaller particle sizes than for a conventional oxide mixture. This led to smaller grain sizes in Pechini's method ceramics. The microstructures were heterogeneous in both systems, showing grain coarsening. The densification was aided by liquid phase formation, due to copper, in both systems, but the temperature of maximum shrinkage rate was larger for the Pechini's method ceramic because copper had to diffuse to the grain surface. Independently of the preparation method, antimony did not aid densification, and increasing its concentration led to a higher densification temperature and lower shrinkage rate. (C) 2003 Kluwer Academic Publishers.

Effect of cerium (IV) ions on the anticorrosion properties of siloxane-poly(methyl methacrylate) based film applied on tin coated steel

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

Photo-electrochemical investigation of anodic oxide films on cast Ti-Mo alloys I. Anodic behaviour and effect of alloy composition

The anodic behaviour of cast Ti-Mo alloys, having different Mo contents (6-20 wt.%), was investigated in acidic and neutral aerated aqueous solutions. All sample showed a valve-metal behaviour, owing to formation and thickening of barrier-type anodic oxides displaying interference colours Growth kinetics. of passive films is influenced by both anodizing electrolyte and composition of the starting alloy. This last parameter was found to change also the solid-state properties of the films, explored by photoelectrochemical and impedance spectroscopy experiments. Thicker films (U(f) = 8 V/MSE) grown on alloys richer in Mo showed more resistive character and a photocurrent sign inversion under negative bias, that revealed an insulating character, whereas corresponding films grown on alloys with lower Mo content, as well as thinner films, behaved as n-type semiconductors. Results are discussed in terms of formation of a mixed Ti-Mo oxide phase. (C) 2008 Elsevier Ltd. All rights reserved

Photocatalyst TiO2-Co: the effect of doping depth profile on methylene blue degradation

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