Síntese de hidroxiapatita pelo método sol-gel utilizando precursores alternativos: nitrato de cálcio e ácido fosfórico

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

Influência dos íons K+ e Mg2+ na obtenção de apatitas biomiméticas

O crescimento da hidroxiapatita - HA, tanto no meio biológico quanto em soluções aquosas como a Synthetic Body Fluid - SBF, ocorre em meio contendo, além dos elementos Ca e P, elementos-traços essenciais tais como: Mg2+, HCO3-, K+ e Na+. Alguns destes elementos são conhecidos como inibidores do crescimento da HA, como Mg2+ e HCO3-. Neste trabalho, estudou-se a influência dos íons K+ e Mg2+ na formação de apatitas sobre substratos metálicos de Ti c.p. previamente tratados com NaOH 5M. Os efeitos destes íons no recobrimento obtidos, antes e após o tratamento térmico a 800ºC, foram analisados por microscopia eletrônica de varredura - MEV, espectroscopia de energia dispersiva de raios-X - EDX, difratometria de raios-X - DRX e espectroscopia no infravermelho - IV e mostraram que o efeito inibitório do Mg2+ na formação da HA se manifesta após o tratamento térmico. Diferentemente, o crescimento cristalino da HA não foi afetado pela presença do íon K+. Além disso, a formação de apatita carbonatada se deu também em soluções que não continham o íon CO3(2-) em sua composição.

Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dependence of annealing time on structural and morphological properties of Ca(Zr0.05Ti0.95)O-3 thin films

Ca(Zr0.05Ti0.95)O-3 (CZT) thin films were prepared by the polymeric precursor method by spin-coating process. The films were deposited on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates and annealed at 650 degrees C for 2,4, and 6 It in oxygen atmosphere. Structure and morphology of the CZT thin films were characterized by the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and field-emission scanning electron microscopy (FEG-SEM). XRD revealed that the film is free of secondary phases and crystallizes in the orthorhombic structure. The annealing time influences the grain size, lattices parameter and in the film thickness. (c) 2006 Elsevier B.V. All rights reserved.

Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

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

Preparation and characterization of new glassy system As2P2S8-Ga2S3

Glasses having the composition (100 - x)As2P2S8-xGa(2)S(3) with x ranging from 0 to 50% were investigated to determine the compositional effect on properties and local structure. The glass transition temperature (T-g) and the stability parameter against crystallization (T-x - T-g) increased with the addition of Ga2S3. The structure of these glasses was probed by Raman scattering, Fourier transform infrared (FT-IR) and P-31 nuclear magnetic resonance. on the basis of the observed vibrations and the strength of the P-31-P-31 homonuclear magnetic dipolar coupling, two scenarios can be proposed for the structural evolution induced by the addition of Ga2S3. For x <= 20% we may have the formation of GaS4E- groups (E = nonbonding electron), and for x >= 30% we have depolymerization of the As2P2S8 units and the formation of a network of GaPS4 units with each PS4/2 unit (Q(4)) species carrying a single positive formal charge.

Retention Characteristics of CBTi144 Thin Films Explained by Means of X-Ray Photoemission Spectroscopy

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

Estudo do comportamento térmico dos compostos de Ag+ e Pb2+ com o ligante 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno

Este trabalho reporta o estudo de compostos binários do dicarboxilato 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno, C6H4(-CH=CH-CO-COO-)2 , com os cátions metálicos Ag+ e Pb2+, obtidos a partir de soluções aquosas do ligante e dos nitratos dos cátions metálicos, em proporções estequiométricas. Para a caracterização e o estudo do processo de decomposição térmica desses compostos foram empregadas Espectrofotometria de Absorção na Região do Infravermelho com Transformada de Fourier (FT-IR), Análise Elementar (C, H), Complexometria com EDTA, Termogravimetria (TG) e Calorimetria Exploratória Diferencial (DSC).

A Simple and Fast Method for the Production and Characterization of Methylic and Ethylic Biodiesels from Tucum Oil via an Alkaline Route

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determination of Copper, Iron, Nickel and Zinc in fuel kerosene by FAAS after adsorption and pre-concentration on 2-aminothiazole-modified silica gel

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

Structural aspects, thermal behavior, and stability of a self-assembled supramolecular polymer derived from flunixin-meglumine supramolecular adducts

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

New phosphinate ligand synthesis and its effect on optical properties of the europium beta-diketonate complex

The synthesis and characterization of a new organic ligand monooctyldiphenylphosphinate (L) is described, as well as a new Eu(3+) diketonate complex [Eu(tta)(3)(L)(2)] (tta = thenoyltrifluoracetone). The ligand (L) was formed by substitution reaction (80% yield) and characterized by uni- and bidimensional (1)H, (13)C and (31)P NMR experiments, to confirm its molecular structure. The coordination of (L) to Eu(3+) in the complex [Eu(tta)(3)(L)(2)] was confirmed by FT-IR spectra. The emission spectra present the same profile when excited in Eu(3+) or in the ligands, suggesting an energy transfer from ligands to Eu(3+) ions. The emission spectra of the precursor [Eu(tta)(3)(H(2)O)(2)], and [Eu(tta)(3)(L(2))] present bands arising from f-f intra-configurational transitions. The only (5)D(0)-(7)F(0) transition shows the presence of at least one site without symmetry center. The FWHM of such transition is 7 cm(-1) and 57 cm(-1) for [Eu(tta)(3)(H(2)O)(2)] and [Eu(tta)(3)(L)(2)] complexes, respectively. This widening is provided by the presence of large groups around Eu(3+) ion. The calculated intensity parameters Omega(2) and Omega(4) show that the interaction features between center-ion and ligand are different; the small value of Omega(4) is related to long range effects of alkyl chain. The Langmuir isotherms of this ligand and complex have been investigated although their hydrolysis in water subphase does not allow stable monolayers. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Comparative vibrational spectra of pilosine and epiisopilosine crystals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ab initio study of high tridymite by the formalism generator coordinate Hartree-Fock

The Generator Coordinate Hartree-Fock (GCHF) Method is applied to generate extended 14s 8p and 17s 11p Gaussian basis sets for the atoms O and Si, respectively. The role of the weight functions in the assessment of the numerical integration range of the GCHF is shown. The Gaussian basis sets are contracted to [6s4p] O atom and [8s5p] Si atom by the Dunning's segmented contraction scheme. To evaluate the quality of our contracted [6s4p] and [8s5p] bases in molecular calculations we accomplish calculations of total and orbital energies in the Hartree-Fock-Roothaan method for O-2 and SiO molecules. We compare the results obtained with the our (14s 8p) and (17s 11p) bases sets with the of 6-311G basis and with values from the literature. The addition of one d polarization function in the silicon basis and its utilization with the basis for oxygen leads to the calculation of electronic properties and IR Spectrum of high tridymite in space group D-3d. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Dynamical study of ZnO nanocrystal and Zn-HDS layered basic zinc acetate formation from sol-gel route

We have pointed out that zinc based particles obtained from ethanolic solution of a zinc acetate derivative (zinc oxy-acetate, Zn4O(Ac)(6)) are a mixture of nanometer sized ZnO, zinc oxy-acetate, and zinc hydroxide double salt (Zn-HDS). The knowledge of the mechanisms involved in the formation of ZnO and Zn-HDS phases, and the evolution of Zn species in reaction medium was monitored in situ during 14 h by simultaneous measurements of UV-vis absorption and extended X-ray absorption fine structures (EXAFS) spectra. This spectroscopic monitoring was initialized just after the addition of an ethanolic lithium hydroxide solution ([LiOH]/[Zn] = 0. 1) to the reaction medium kept under controlled temperature (40 degrees C). This study points out the first direct evidence of the reaction between ZnO nanoparticles and unreacted zinc oxy-acetate to form a Zn-HDS phase. The dissolution of ZnO and the reprecipitation of Zn-HDS are induced by the gradual release of water mainly produced by ethanol esterification well evidenced by gas chromatography coupled to mass spectroscopy and FT-IR measurements.