Degradation of the surface of a metasilicate glass due to atmosphere moisture

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

Uso das técnicas de infravermelho e de ressonância magnética nuclear na caracterização da reação ácido-base de um cimento odontológico experimental

Glass ionomer cements (GICs) are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid) in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental and to investigate the structural changes during hardening of the cements by FTIR and Al MAS NMR. These analyses showed that the experimental glass powder reacted with organic acid to form the GICs and it is a promising material to manufacture dental cements.

Preparation of hierarchically structured porous aluminas by a dual soft template method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparation of different basic Si-MCM-41 catalysts and application in the Knoevenagel and Claisen-Schmidt condensation reactions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The influence of thermal treatment on the preparation of PNM and PMN-PT thin films

Ferroelectric thin films belong to a class of materials with great technological importance in optic fibers, micro-electromechanical systems, and microprocessors and computers memories.The (1-x)PbMg1/3Nb2/3O3(x)PbTiO3 (PMN-PT) thin films, with x=0, 0.1, 0.35 and 0.5, were prepared by Pechini's process and deposited by spin-coating on Si(100), Pt/Ti/SiO2/Si(100) and quartz substrates. The goal of the present paper is to verify the thermal treatment influence on the perovskite phase formation, which is desirable for these applications. The phase formation was analyzed by X-ray diffraction. The film's surface was characterized by atomic force microscopy to analyze the roughness and the homogeneity. The results of this study indicate that the optimum conditions for obtaining the perovskite phase using a Pt/Ti/SiO2/Si(100) substrate, were drying each deposited layer at 140 degreesC (heating plate), and a final thermal treatment at 600 degreesC for 3 h in a closed system with a lead-rich atmosphere. (C) 2003 Elsevier B.V. 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.

SnO2 nanoparticles functionalized in amorphous silica and glass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preparation and thermal decomposition of copper(II), zinc(II) and cadmium(II) chelates with 8-hydroxyquinoline

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

Preparation and Characterization of Graphite-Epoxy Composite Modified with Zinc Hexacyanoferrate and Their Electrochemical Behaviour in Presence of Substituted Anilines

The growth of zinc hexacyanoferrate (ZnHCF) hybrid film on the surface of graphite-epoxy composite (GEC) electrodes was demonstrated by cyclic voltammetry. Surface morphology of the hybrid film was investigated by using scanning electron microscopy. The effect of the type of monovalent cations on the redox behaviour of hybrid film was also studied. This effect indicated that the radius of the hydrated cation mainly determines the ion permeability of the film.The electrochemical behavior of the substituted anilines (procaine and sulfamerazine) in 1 M KCl of the modified GEC electrode showed a decrease of the cathodic currents while increasing the concentration of these analytes. The developed sensor also showed excellent stability for long time usage, higher sensitivity and cost-effective fabrication.

Determination of macro- and micronutrients in plant leaves by high-resolution continuum source flame atomic absorption spectrometry combining instrumental and sample preparation strategies

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

Evaluation of Lubricating Oil Preparation Procedures for the Determination of Al, Ba, Mo, Si and V by High-Resolution Continuum Source FAAS

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

Silver Nanocomposite Electrode Modified with Hexacyanoferrate. Preparation, Characterization and Electrochemical Behaviour Towards Substituted Anilines

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Internal standardization combined with dilute-and-shoot preparation of distilled alcoholic beverages for Cu determination by high-resolution continuum source flame atomic absorption spectrometry

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

Preparation and thermal study of Mg-diclofenac compound in solid state

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Microeletrodos: I. Construção e caracterização

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