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971.
Maria Raimo 《Progress in Crystal Growth and Characterization of Materials》2011,57(2-3):65-92
This work reviews criteria for the successful application of regime analysis to polymers and also discusses the influence of accuracy of input variables on the results. Despite that it has often been stated that the uncertainty in the input parameters remarkably affects the trustworthiness of the outcomes of the regime analysis, the literature offers on the subject only a fragmentary information and there is no paper looking over all the effects of accuracy of the input parameters. Here the influence of errors in input parameters has been investigated and methods to test the reliability of thermodynamic outcomes have been discussed. Mathematical ways to ascertain the accuracy of the input parameters consist in comparisons between the growth rates expressed by the Hoffman–Lauritzen equation and their derivatives generated by means of the output of the regime analysis. These comparisons, under the hypothesis of validity of the secondary nucleation theory, allow excluding the presence of remarkable errors in input values and variables. 相似文献
972.
973.
Mechanical properties of anion exchange membranes by combination of tensile stress–strain tests and dynamic mechanical analysis
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Riccardo Narducci J.‐F. Chailan A. Fahs Luca Pasquini Maria Luisa Di Vona Philippe Knauth 《Journal of Polymer Science.Polymer Physics》2016,54(12):1180-1187
The thermomechanical properties of anion exchange polymers based on polysulfone (PSU) quaternized with trimethylamine (TMA) or 1,4‐diazabicyclo[2.2.2]octane (DABCO) and containing hydroxide or chloride anions by tensile stress–strain tests and dynamic mechanical analysis (DMA) have been determined. The reported mechanical properties included the Young's modulus, tensile strength, and elongation at break from tensile tests and the storage and loss modulus and glass transition temperature from DMA. The anion exchange membranes behaved as stiff polymers with Young's modulus in the order of 1 GPa, relatively with high strength (about 30 MPa) and low elongation at break (around 10%) was observed. Tensile tests were also made with membranes exchanged with hydrogen‐carbonate and carbonate anions to control the absence of important carbonation of the OH form. The glass transition temperatures were of the order of 150 °C (PSU‐TMA) or 200 °C (PSU‐DABCO) for the hydroxide form, confirmed by differential scanning calorimetry; they increase further by about 50 K, when hydroxide ions are replaced by chloride. This result and the increase of the storage modulus could be interpreted by the higher hydration of hydroxide ions and the plasticizing effect of water, which reduced the Van der Waals interactions between the macromolecular chains. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1180–1187 相似文献
974.
975.
Maria Caterina Fragnelli Pilar Hoyos Diego Romano Raffaela Gandolfi Andrés R. Alcántara Francesco Molinari 《Tetrahedron》2012,68(2):523-528
Water/organic solvent two-liquid-phase systems have been successfully applied in the synthesis of enantiomerically pure (S)-benzoin through two different methodologies catalysed by whole cells from the non-conventional yeast Pichia glucozyma: the stereoselective monoreduction of benzil and the deracemisation of benzoin. The presence of the organic solvent influences the redox systems implied in the reactions, avoiding the formation of the corresponding diols, increasing the enantioselectivity and allowing the easy isolation of the products in high yields and excellent enantiomeric excesses. The use of both strategies has been extended to the preparation of different chiral benzoin derivatives. 相似文献
976.
977.
978.
Maria G. Chernysheva Gennadii A. Badun 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):835-840
A new technique for in vitro studies of biomacromolecules interactions, their adsorption at aqueous/organic liquid interfaces
and distribution in the bulk of liquid/liquid systems was developed. The method includes (1) tritium labeling of biomolecules
by tritium thermal activation method and (2) scintillation phase step with organic phase, which can be concerned as a model
of cellular membrane. Two globular proteins lysozyme and human serum albumin tested. We have determined the conditions of
tritium labeling when labeled by-products can be easy separated by means of dialysis and size-exclusion chromatography. Scintillation
phase experiments were conducted for three types of organic liquids. Thus, the influences of the nature of organic phase on
proteins adsorption and its distribution in the bulk of aqueous/organic liquid system were determined. It was found that proteins
possess high surface activity at aqueous/organic liquid interface. Furthermore, values of hydrophobicity of globular proteins
were found by the experiment. 相似文献
979.
Maria J. Alves Vera C.M. Duarte Hélio Faustino António Gil Fortes 《Tetrahedron: Asymmetry》2010,21(15):1817-1820
Erythrose benzylidene-acetal 1,3-butadienes are studied as partners in Diels–Alder cycloadditions. A high diastereofacial improvement is found in cases where both the alcohol function is protected and a π–π interaction between the diene and dienophile is possible. Several competing factors have been studied independently in order to explain its influence on the selectivity of the cycloadditions. 相似文献
980.
Soraa Bouattour Wannes Kallel Ana Maria Botelho do Rego L.F. Vieira Ferreira I. Ferreira Machado Sami Boufi 《应用有机金属化学》2010,24(10):692-699
This work reports on the synthesis of Li‐doped TiO2 nanoparticles using the sol–gel process and solid‐state sintering, and investigates their potential use as a photocatalyst for degradation under sunlight excitation of different organic model compounds in aqueous solution. The structure of the nanocrystals was examined by X‐ray diffraction, UV‐vis ground state diffuse reflectance absorption spectra and X‐ray photoelectron emission spectroscopy. Results showed that samples prepared by sol–gel process and calcined at 400 °C are composed of a mixture of anatase and rutile phases, in contrast to the one prepared by solid‐state sintering, which exhibits an anatase phase with Li being involved in a spinel phase. The photocatalytic degradation of aqueous solutions of different aromatic compounds was successfully achieved under sunlight excitation in presence of Li‐doped TiO2 prepared via sol–gel process. It was shown that the calcination temperature and the preparation mode greatly affect the photocatalytic efficiency. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献