Synchrotron X-ray powder diffraction data of atorvastatin

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

Crystal Structure Determination of Mebendazole Form A Using High-Resolution Synchrotron X-Ray Powder Diffraction Data

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

The interaction between atoms of Au and Cu with clean Si(111) surface: A study combining synchrotron radiation grazing incidence X-ray fluorescence analysis and theoretical calculations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

X-ray diffraction data of tibolone Delta(4) isomer (isotibolone)

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

Crystal structure of propylthiouracil determined using high-resolution synchrotron X-ray powder diffraction

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

Powder X-ray characterization of lithium thiazoildine-4-carboxylate

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

Structural investigations of tungsten silver phosphate glasses by solid state NMR, vibrational and X-ray absorption near edge spectroscopies

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

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)

Structural and optical properties of GdAlO3:RE3+ (RE = Eu or Tb) prepared by the Pechini method for application as X-ray phosphors

In this work, GdAlO3:RE3+ (RE = Eu or Tb) was successfully prepared by the Pechini method at lower temperatures when compared to others methods as solid-state synthesis and sol-gel process. In accordance to the XRD data, the fully crystalline single-phase GdAlO3 could be obtained at 900 degrees C. The differential thermal analysis (DTA) shows a crystallization peak at 850 degrees C. The samples are composed by monocrystalline particles (50-120 nm) exhibiting the formation of aggregates among them, which indicates the beginning of the sinterization process. This feature indicates a strong tendency to the formation of aggregates, which is a suitable ability for the close-packing of particles, and hence a potential application in X-ray intensifying screens. Luminescence measurements indicate Gd3+ -> RE3+ energy transfer. The Eu3+ emission spectra exhibit all the characteristics D-5(0) -> F-7(j) transitions and the observed profile suggests that RE3+ ions occupy at least one site without center of symmetry. For terbium-doped samples, the D-5(3) -> F-7(j) (blue emission) and D-5(4) -> F-7(j) (green emission) transitions were observed and the ratio between them may depend on the Tb3+ content due to cross-relaxation processes. (C) 2009 Elsevier B.V. All rights reserved.

Structural study of thin films prepared from tungstate glass matrix by Raman and X-ray absorption spectroscopy

Thin films were prepared using glass precursors obtained in the ternary system NaPO(3)-BaF(2)-WO(3) and the binary system NaPO(3)-WO(3) with high concentrations of WO(3) (above 40% molar). Vitreous samples have been used as a target to prepare thin films. Such films were deposited using the electron beam evaporation method onto soda-lime glass substrates. Several structural characterizations were performed by Raman spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES) at the tungsten L(I) and L(III) absorption edges. XANES investigations showed that tungsten atoms are only sixfold coordinated (octahedral WO(6)) and that these films are free of tungstate tetrahedral units (WO(4)). In addition, Raman spectroscopy allowed identifying a break in the linear phosphate chains as the amount of WO(3) increases and the formation of P-O-W bonds in the films network indicating the intermediary behavior of WO(6) octahedra in the film network. Based on XANES data, we suggested a new attribution of several Raman absorption bands which allowed identifying the presence of W-O and W=O terminal bonds and a progressive apparition of W-O-W bridging bonds for the most WO(3) concentrated samples (above 40% molar) attributed to the formation of WO(6) clusters. (C) 2008 Elsevier B.V. All rights reserved.

Biological Activity of Quinoline Alkaloids from Raulinoa echinata and X-ray Structure of Flindersiamine

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

Seed weight of Xylopia aromatica (Annonaceae): quality evaluation from X-ray and seedling emergence

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

Synthesis, electrochemical behavior and X-ray crystal and molecular structures of [Fe(diene)(CO)(2)PPh3] (diene = chalcone, sorbic acid)

The compounds [Fe(ch)(CO)(2)PP3] (1) (ch = chalcone) and [Fe(sba)(CO)(2)PPh3] (2) (sba = sorbic acid) were prepared by irradiating the tetracarbonyltriphenylphosphineiron(0) complex in benzene in the presence of ch or sba. The compounds were characterized by infrared and P-31 NMR spectroscopies. Their electrochemical behavior was investigated by cyclic voltammetry and the results suggest that their oxidations occur by more than one electrochemical step, producing free ch and sba, free PPh3 and solvated Fe(III). It was observed that sba ligand contributes more effectively to the stabilization of metal center in these complexes, the X-ray crystal and molecular structures of 1 and 2 were determined; it was shown that the Fe atom adopts a distorted octahedral coordinated geometry in which three of the sites are occupied by the ch or sba ligand. The [Fe(ch)(CO)(2)PPh3] complex is a monomer and the unit cell of complex 2 contains exist two identical and crystallographically independent molecules of [Fe(sba)(CO)(2)PPh3] which are linked by short hydrogen bonds O-H . . .O (C) 2001 Published by Elsevier B.V. Ltd.

Mass fractal characteristics of silica sonogels as determined by small-angle x-ray scattering and nitrogen adsorption

A sample series of silica sonogels was prepared using different water-tetraethoxysilane molar ratio (r(w)) in the gelation step of the process in order to obtain aerogels with different bulk densities after the supercritical drying. The samples were analyzed by means of small-angle x-ray-scattering (SAXS) and nitrogen-adsorption techniques. Wet sonogels exhibit mass fractal structure with fractal dimension D increasing from similar to2.1 to similar to2.4 and mass-fractal correlation length xi diminishing from similar to13 nm to similar to2 nm, as r(w) is changed in the nominal range from 66 to 6. The process of obtaining aerogels from sonogels and heat treatment at 500degreesC, in general, increases the mass-fractal dimension D, diminishes the characteristic length xi of the fractal structure, and shortens the fractal range at the micropore side for the formation of a secondary structured particle, apparently evolved from the original wet structure at a high resolution level. The overall mass-fractal dimension D of aerogels was evaluated as similar to2.4 and similar to2.5, as determined from SAXS and from pore-size distribution by nitrogen adsorption, respectively. The fine structure of the secondary particle developed in the obtaining of aerogels could be described as a surface-mass fractal, with the correlated surface and mass-fractal dimensions decreasing from similar to2.4 to similar to2.0 and from similar to2.7 to similar to2.5, respectively, as the aerogel bulk density increases from 0.25 (r(w)=66) up to 0.91 g/cm(3) (r(w)=6).

Small-angle X-ray scattering and nitrogen adsorption study of the nanoporosity elimination in TEOS sonohydrolysis-derived xerogels

Small-angle X-ray scattering (SAXS) and nitrogen adsorption techniques were used to study the temperature and time structural evolution of the nanoporosity in silica xerogels prepared from acid- and ultrasound-catalyzed hydrolysis of tetraetboxysilane (TEOS). Silica xerogels present a structure of nanopores of fully random shape, size, and distribution, which can be described by an exponential correlation function gamma(r) = exp (-r/a), where a is the correlation distance, as predicted by the Debye, Anderson, and Brumberger (DAB) model. The mean pore size was evaluated as about 1.25 nm from SAXS and about 1.9 nm from nitrogen adsorption. The nanopore elimination in TEOS sonohydrolysis-derived silica xerogels is readily accelerated at temperatures around 900 degrees C probably by the action of a viscous flow mechanism. The nanopore elimination process takes place in such a way that the pore volume fraction and the specific surface are reduced while the mean pore size remains constant. (c) 2005 WILEY-VCH Verlag GmbH S Co. KGaA, Weinheim.