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991.
992.
A complete set of protonated water clusters conformers up to n = 8 have been evaluated by ab-initio Hartree-Fock method in 6-311G** molecular orbitals basis set and with quadratic complete basis set method. Configurations of ground-state conformers are in a good accord with those available in literature but present dissociation energies for the light clusters agree better with experimental values. A tentative analysis of experimental conditions for observation of certain clusters is presented in comparison to selected formation paths of clusters. Dissociation energies show a broad range of values. 相似文献
993.
Marek Biziuk Edmund Kozłowski Alicja Błasiak 《International journal of environmental analytical chemistry》2013,93(3):147-151
Abstract The present method is based on preconcentration of organic contaminants on XAD-4 as sorbent, thermal desorption, mineralization and coulometric argentometric titration for the final determination of halides. The results were calculated as the total parameter VOX (volatile organic halogen) expressed as chlorine. The method has been used for the VOX determination in tap water, Vistula river water and Baltic Sea water. Sampling of the Baltic Sea water has been carried out during the research cruise of the r/v ‘Oceania’. The relatively high anthropogenic pollution of the river Vistula (c vox = 11–45 μg Cl/cd3), Gulf of Gdańsk (c vox = 0.6–4.5 μg Cl/dm3) and the Pomerania Bay (c vox = 2 μg Cl/dm3) has been determined. The VOX concentration in the tap water varied between 13 and 56 μg/dm3; that is, this water is seriously polluted by volatile organic halogen compounds. 相似文献
994.
M. Duque‐Bernal J. D. Quintero‐Arias W. Osorio‐Viana I. Dobrosz‐Gómez J. Fontalvo M. Á. Gómez‐García 《国际化学动力学杂志》2013,45(1):10-18
The liquid‐phase esterification of acetic acid and isoamyl alcohol has been studied to develop a kinetic model using a sequential experimental design based on the divergence criterion. Data come from batch reactor experiments, performed in the temperature range of 316–363 K. Discrimination among 36 possible kinetic models, written in terms of activity, mole fractions, and molar densities, is possible through the deviance information criterion, as estimated by a Markov chain Monte Carlo technique. The obtained results indicate a negligible heat of reaction and a clear autocatalytic effect of acetic acid on the esterification rate. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 10–18, 2013 相似文献
995.
Jan Pecháček Jiří Václavík Jan Přech Petr Šot Jakub Januščák Beáta Vilhanová Jiří Vavřík Marek Kuzma Petr Kačer 《Tetrahedron: Asymmetry》2013,24(4):233-239
We present, to the best of our knowledge, the first parametric study of the asymmetric transfer hydrogenation of imines catalyzed by a Noyori-type catalytic complex based on ruthenium. A model imine for this study was 1-methyl-3,4-dihydroisoquinoline, and a well-known complex RuCl(η6-p-cymene)((1S,2S)-N-p-toluenesulfonyl-1,2-diphenylethylenediamine) was chosen as the model catalyst. The reactions were performed in the presence of a formic acid–triethylamine mixture as the source of hydrogen.The parameters examined include general parameters, for example, concentration, temperature, and substrate-to-catalyst molar ratio, as well as parameters specific to this particular reaction, such as the amount of the hydrogenation mixture used, the ratio of its components, or the inhibitive effect of carbon dioxide. During this study, several unexpected parameters worth further investigation have emerged. 相似文献
996.
B. Schäffer L. Daróczi B. Keller Z. Szakály D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1891-1896
Due to the increasing consumers’ interest in up-to-date nutrition nowadays the production of main part of fermented dairy products (e.g. yogurt, kefir) is performed using probiotic microbes. The majority of this product group are the flavoured variations, the sweetener is, first of all, still refined sugar (e.g. saccharose). Honey of natural origin, consequently preferred from the nutrition-physiological point of view, could be proposed to replace this refined carbohydrate. To check its availability for this purpose the growth of microbes of the Hungarian culture of trade name Prebiolact-2 was examined. The probiotic properties of the culture are proved by clinical tests. At the determination of recipes of control and experimental samples we took into consideration that the milk composition and carbohydrate content of samples should have been the same, and they could differ only in carbohydrate-free component content of honey. During processing of the samples the minimum heat-treatment was applied to protect the biologically active components of honey to the greatest degree. Pasteurized-homogenized milk was used as raw material, in which granulated sugar and the honeys were solved, respectively, at 60 °C. The inoculation was made by Prebiolact-2 culture injected into the batch-wessel; the closed cells were agitated intensively for 10 s. General conclusion of thermal investigation is that the proliferation rate is longer lasting in case of honey treated milks. The acacia- honey resulted in the same probiotic proliferation as sugar did. In case of other herb-honeys the effect was smaller, very probably because of the strong bactericidal effect of herbs, which is very important from medical point of view. According to the results of the consumer survey over 85 % of them think that the consumption of herbs in the form of honey is especially beneficial from both dietary and market view. 相似文献
997.
Raman and IR spectroscopy have been used to elucidate the solvation process in a mixed water-acetonitrile solvent in the CN stretching region. The number and positions of the components forming the spectral contour are established by Fourier deconvolution and Factor analysis and their areas are determined by fitting. The forms of existence of acetonitrile in the mixed solvent are discussed. 相似文献
998.
Attila Kormos Ildikó Móczár Dávid Pál Péter Baranyai József Kupai Klára Tóth Péter Huszthy 《Tetrahedron: Asymmetry》2013,24(1):62-65
A novel optically active 5,5-dioxophenothiazine-1,9 bis(thiourea) containing glucopyranosyl groups was synthesized and its enantiomeric recognition properties were examined towards the enantiomers of tetrabutylammonium salts of chiral α-hydroxy and N-protected α-amino acids using UV–vis spectroscopy. 相似文献
999.
E. Kuzmann A. Vértes G. Bohus V. Hornok A. Oszkó I. Dékány 《Hyperfine Interactions》2013,218(1-3):23-28
151Eu Mössbauer spectroscopy was applied to distinguish among different Eu microenvironments and phases in spherical Y2O3:Eu3?+? and core-shell Y2O3@Eu3?+? phosphor nanoparticles prepared by using homogeneous precipitation method. 151Eu isomer shift revealed that Eu atoms exist only in oxidation state Eu3?+? in all spherical and core-shell phosphors. Significant differences have been found between the Mössbauer parameters (isomer shift, principal component of EFG and linewidth) characteristic of spherical Y2O3:Eu3?+? and core-shell Y2O3@Eu3?+? phosphor nanoparticles. The Mössbauer parameters of spherical Y2O3:Eu3?+? were associated with Eu substituting Y in the Y2O3, while Mössbauer parameters of core-shell Y2O3@Eu3?+? phosphor were attributed to Eu being in the Eu2O3 shell, proving the structural model and the successful preparation of these phosphors. 相似文献
1000.
Andrés Alessandro León Baldelli Blaise Bourdin Jean-Jacques Marigo Corrado Maurini 《Continuum Mechanics and Thermodynamics》2013,25(2-4):243-268
We study multi-fissuration and debonding phenomena of a thin film bonded to a stiff substrate using the variational approach to fracture mechanics. We consider a reduced one-dimensional membrane model where the loading is introduced through uniform inelastic (e.g., thermal) strains in the film or imposed displacements of the substrate. Fracture phenomena are accounted for by adopting a Griffith model for debonding and transverse fracture. On the basis of energy minimization arguments, we recover the key qualitative properties of the experimental evidences, like the periodicity of transverse cracks and the peripheral debonding of each regular segment. Phase diagrams relate the maximum number of transverse cracks that may be created before debonding takes place, as a function of the material properties and the sample’s geometry. The theoretical results are illustrated with numerical simulations obtained through a finite element discretization and a regularized variational formulation of the Ambrosio–Tortorelli type, which is suited to further extensions in two-dimensional settings. 相似文献