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141.
JPC – Journal of Planar Chromatography – Modern TLC - Direct enantioresolution of (±)-etodolac has been achieved by adopting a new conceptual approach involving both achiral phases... 相似文献
142.
Static model coefficients for an algebraic subgrid stress (SGS) model are determined using a dynamic approach, based on results from simulations of isotropic decaying turbulence. The study was motivated by the discrepancies in energy transfer predictions using the previously documented coefficients (Bhushan and Warsi, Int. J. Numer. Meth. Fluids 2005; 49 : 489–519). The discrepancies are identified to be due to inconsistent filter functions used in the analytic estimates and the simulations. The study emphasizes that SGS model development should use filter functions compatible with those inherent in CFD application solvers. The dynamic approach predicts consistent model and transfer coefficients for different grid resolutions and is judged to be a reliable basis for model coefficient adjustments. The predicted Leonard's stress coefficient and associated energy transfer coefficients agree very well with the analytic estimates using a Gaussian/cutoff combination filter. This suggests that the modeling of Leonard's stress term using a truncated Taylor series expansion is robust and may not benefit significantly from dynamic modeling. Validation simulations were performed for turbulent channel flow at Reτ = 180 and 590. The dynamic approach was found to be reliable only for the lower log‐layer of the Reτ = 590 case, where the scale invariance condition was satisfied. Nonetheless, in this narrow range, the model and transfer coefficients compare well with the isotropic case. The static coefficient algebraic model with new adjusted coefficients shows improved predictions compared with the previous coefficients, for both isotropic decaying turbulence and channel flow cases. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
143.
The extraction of ammine complexes of Cu2+, Cd2+, Ni2+, Co2+ and Zn2+ by synthesised manganese, nickel and zinc silicates has been studied at different pH and ionic concentrations in the external
solution. It has been found that the uptake of the metal ion Co2+, Cu2+ and Zn2+ increases with increase in pH of the external solution, attains a maximum and then decreases. However, the uptake for Cd2+ and Ni2+ increases continuously. The qA values of all the silicates increases with the increase in the concentration of the exchanging ion and its order for the
investigated metal ions is Ni2+ < Co2+ < Cd2+ < Zn2+ < Cu2+. 相似文献
144.
145.
Narender K. Kaushik Bharat Bhushan Gurdeep R. Chhatwal 《Transition Metal Chemistry》1978,3(1):215-217
Summary Titanium(IV)N,N-dialkyldithiocarbamates of the type 5-Cp2Ti (S2CNR2)Cl and (5-MeCp)2Ti(S2CNR2)Cl (R = Me, Et and i-Pr) have been prepared by the reaction of di--cyclopentadienyldichlorotitanium(IV) and bis-n-methylcyclopentadienyldichlorotitanium(IV) with sodium salts of dithiocarbamic acids in refluxing dichloromethane. Molecular weight, conductance and i.r. studies show these complexes to be monomeric nonelectrolytes in which the dithiocarbamate ligands are bidentate. Therefore, pentacoordination may be assigned to titanium(IV) atom in all six complexes. Electronic and proton n.m.r. studies spectra have also been recorded for the complexes. 相似文献
146.
Different metal salts have been tried as impregnating reagents for developing TLC separation schemes for some antihistamines on silica gel 'G' plates, using a new solvent system benzene + dimethyl formamide + acetic acid (30:10:7). Spots were visualized by spraying with a solution of Dragendroff's reagent. 相似文献
147.
Szoszkiewicz R Bhushan B Huey BD Kulik AJ Gremaud G 《The Journal of chemical physics》2005,122(14):144708
Correlations between adhesion hysteresis and local friction are theoretically and experimentally investigated. The model is based on the classical theory of adhesional friction, contact mechanics, capillary hysteresis, and nanoscale roughness. Adhesion hysteresis was found to scale with friction through the scaling factor containing a varying ratio of adhesion energy over the reduced Young's modulus. Capillary forces can offset the relationship between adhesion hysteresis and friction. Measurements on a wide range of engineering samples with varying adhesive and elastic properties confirm the model. Adhesion hysteresis is investigated under controlled, low humidity atmosphere via ultrasonic force microscopy. Friction is measured by the friction force microscopy. 相似文献
148.
TLC of a fifteen component mixture of amino acids has been carried out in two ways; firstly, the amino acids were treated
with halides below their isoelectric points and chromatographed on plain silica plates, and secondly the amino acids in their
cationic forms were chromatographed on silica plates impregnated with halides, keeping the same solvent system. The resolution
is considered to be affected by hydrophobic interactions between silica gel and amino acid molecule and by the polarity and
the flow of the mobile phase. The method provides resolution of 10–11 amino acids from the fifteen component mixture. 相似文献
149.
Traces of cadmium from relatively high amounts of nickel and copper can be separated by the selective sorption of the cadmium
ethylenediamine complex on hydrous ferric oxide. A batch chromatographic technique has been elaborated on this basis. 相似文献
150.