Uberaba, Brazil
Uberaba, Brazil

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Alessio O.,Institute of Exact science | Duldul M.,Yildiz Technical University | Uyar Duldul B.,Yildiz Technical University | Badr S.A.-N.,Assiut University | Abdel-All N.H.,Assiut University
Computer Aided Geometric Design | Year: 2014

The urpose of this paper is to present algorithms for computing all the differential geometry properties of non-transversal intersection curves of three parametric hypersurfaces in Euclidean 4-space. For transversal intersections, the tangential direction at an intersection point can be computed by the extension of the vector product of the normal vectors of three hypersurfaces. However, when the three normal vectors are not linearly independent, the tangent direction cannot be determined by this method. If normal vectors of hypersurfaces are parallel (N1 N2 N3)we have tangential intersection, and if normal vectors of hypersurfaces are not parallel but are linearly dependent we have "almost tangential" intersection. In each case, we obtain unit tangent vector (t), principal normal vector (n), binormal vectors (b1 b2) and curvatures (k1 k2 k3) of the intersection curve. © 2014 Elsevier B.V.

Barra P.M.C.,Institute of Exact science | Oliveira P.L.,Institute of Exact science | Aragao D.M.O.,Institute of Biological science | Sabarense C.M.,Federal University of Juiz de fora | And 5 more authors.
Journal of the Brazilian Chemical Society | Year: 2014

The determination of fatty acids (FA) in liver from three different groups of Wistar rats (six rats by group) submitted to diet (AIN-93G) by capillary zone electrophoresis (CZE) was proposed. Each group received the same diet. However, the soybean oil used to prepare the feed, whose amount was 7% w/w, had different origins. The first group was fed with feed containing soybean oil fresh; the second one was fed with soybean used during 7 days in deep frying process; finally, the third was fed with soybean used during 15 days in deep frying process. After 45 days the rats were submitted to euthanasia and the FA amount in liver was successful monitored by CZE in a simple, fast and efficient way. The results obtained were compared to gas chromatography official method and no significant differences were observed within 95% confidence interval. The electropherograms to FA analysis were submitted to principal component analysis (PCA) being possible to discriminate the final from the control and intermediate groups. In addition to PCA results, the low density lipoprotein (LDL) was evaluated indicating that the total time exposure of the oil submitted to deep frying processes can be considered relevant to evaluating the oil quality. © 2014 Sociedade Brasileira de Química.

Freitas P.G.,Federal University of Alfenas | Barbosa A.F.,Federal University of Alfenas | Saraiva L.A.,Institute of Exact science | Camps I.,Institute of Exact science | And 4 more authors.
Journal of Luminescence | Year: 2012

The binding interaction between mangiferin (MGF), which a natural xanthone isolated from mangoes, and bovine serum albumin (BSA) was studied with absorbance and fluorescence spectroscopy, cyclic voltammetry and molecular modeling. The data were analyzed to assess the binding mechanism, effect of pH and ionic strength, conformational changes in the protein and electrical charge transfer involved. The MGF-BSA complex exhibited positive cooperativity with a 1:1 stoichiometry (K d=0.38 mmol L -1) for the first binding site and a non-saturable binding at high ligand concentrations. Furthermore, the data also suggest an increase in drug bioavailability in the acidic region and relatively low ionic strength values, which are close to physiological levels. The data suggest a specific electrostatic interaction together with hydrophobic effects and H-bonding displayed in MGF binding to the BSA IIA subdomain. Synchronous fluorescence spectra indicate that there are conformational changes in the polypeptide backbone upon ligand binding. Cyclic voltammetry indicates that there is an irreversible charge transfer between MGF and BSA that is modulated by diffusion on the electrode surface, where two electrons are transferred. These results can help the knowledge of the pharmacokinetic activities of natural or chemical xanthone-based drugs. © 2012 Elsevier B.V. All rights reserved.

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