Sandra C. C. Nunes

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This work presents an investigation on the conformational preferences of alpha,alpha-trehalose in gas phase and aqueous solution. Eighty-one systematically selected structures were studied at the B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level, giving rise to 40 unique conformers. The 19 lower energy structures and some selected other were further re-optimized at(More)
A study on the thermal behavior of human stratum corneum and lipids is described. The use of high scanning rate DSC for both SC and extracted lipids allows the consistent determination of transition temperatures, including those of lower energy. Changes are found both at physiological and higher temperatures. There is a clear correspondence between the(More)
PURPOSE To use high-speed differential scanning calorimetry (DSC) in the identification of transitions in human stratum corneum (SC). Several scanning rates (100 degrees C/min to 400 degrees C/min) are used. RESULTS Eight transitions from 0 to 120 degrees C are detected in a significant number of samples. Most of these transitions have already been(More)
The structural changes occurring on erythritol as it is cooled from the melt to low temperature, and then heated up to the melting point have been investigated by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM), X-ray powder diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). By DSC, it was possible to(More)
This work focuses on multiple chain deposition, using a coarse-grained model. The phenomenon is assessed from a novel perspective which emphasizes the conformation and relative arrangement of the deposited chains. Variations in chain number and length are considered, and the surface charge in the different systems ranges from partially neutralized to(More)
The molar enthalpy of sublimation, DgcrH m, of trans-cyclohexyl-1,4-diamine and the molar enthalpy of vaporization, D g lH m, of ciscyclohexyl-1,2-diamine, at the temperature 298.15 K, were determined by calorimetry. DgcrH mðT 1⁄4 298:15 KÞ 1⁄4 ð105:0 0:8Þ kJ mol 1 was obtained for the trans-isomer and DglH mðT 1⁄4 298:15 KÞ 1⁄4 ð62:2 1:0Þ kJ mol 1 for the(More)
Beta-adrenoceptor-blocking agents (beta-blockers) are on the list of the top selling drugs. Pindolol is a representative of this type of compound, either from the structural point of view, or as reference for comparison of the pharmacokinetic properties of the beta-blockers. A study of the pindolol structure based on infrared spectroscopy and natural bond(More)
Crystallization of pindolol from the melt was studied by differential scanning calorimetry (DSC) and polarized light thermomicroscopy (PLTM) in order to discriminate the polymorphic forms obtained by this method. The crystallization process originates one exothermic signal localized in two different well-defined temperature ranges. Fusion gives rise to(More)
Adsorption phenomena are relevant in a wide variety of subjects, from biophysics to technological applications. Different aspects, such as molecular recognition, multilayer deposition, and dynamics of polymer adsorption have been addressed. The methodologies used range from analytical and numerical methods to molecular dynamics or Monte Carlo simulations.(More)
The interaction between polyelectrolytes and counterions in confined situations and the mutual relationship between chain conformation and ion condensation is an important issue in several areas. In the biological field, it assumes particular relevance in the understanding of the packaging of nucleic acids, which is crucial in the design of gene delivery(More)