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141.
David M. Arnold Adolf Mader Otto Mutzbauer Ebru Solak 《Czechoslovak Mathematical Journal》2013,63(2):307-355
Almost completely decomposable groups with a critical typeset of type (1, 3) and a p-primary regulator quotient are studied. It is shown that there are, depending on the exponent of the regulator quotient p k , either no indecomposables if k ? 2; only six near isomorphism types of indecomposables if k = 3; and indecomposables of arbitrary large rank if k ? 4. 相似文献
142.
M. Erol Ulucakli 《实验传热》2013,26(4):305-321
Natural-convection heat transfer in a cylindrical enclosure, heated partially from below by a disk-shaped heating surface and cooled from the top and the side, was investigated experimentally and numerically. Heat transfer measurements are presented for the range of Rayleigh numbers from 108 to 2 × 1010. The total acceleration normal to the heating surface was varied from I to 100 times the standard gravitational acceleration. The heat flux was varied from 0.19 MW / m1 to 1.5 MW / m2. The test results were correlated by an equation of the form NuD = 0.2Ra0.325 D for Prandtl number 2 and aspect ratio I. The flow field was studied numerically using FLUENT code. 相似文献
143.
Determination of chromatographic dissociation constants of some carbapenem group antibiotics and quantification of these compounds in human urine 下载免费PDF全文
Ebru Çubuk Demiralay Duygu Koç Y. Doğan Daldal Güleren Alsancak Sibel A. Ozkan 《Biomedical chromatography : BMC》2014,28(5):660-666
The dissociation constant values (sspKa) of some carbapenem group drugs (ertapenem, meropenem, doripenem) in different percentages of methanol–water binary mixtures (18, 20 and 22%, v/v) were determined from the mobile phase pH dependence of their retention factor. Evaluation of these data was performed using the NLREG program. From calculated pKa values, the aqueous pKa values of these subtances were calculated by different approaches. Moreover, the correlation established between retention factor and the pH of the water–methanol mobile phase was used to determine the optimum separation conditions. In order to validate the optimized conditions, these drugs were studied in human urine. The chromatographic separation was realized using a Gemini NX C18 column (250 × 4.6 mm i.d., 5 µm particles) and UV detector set at 220 and 295 nm. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
144.
In this study, polyindole (PIN)/TiO2 nanocomposites were synthesized with and without the presence of sodium dodecylsulfate, anionic surfactant, with two different PIN contents. The synthesized materials were subjected to various characterizations namely: particle size, apparent density, conductivity, dielectric constants, magnetic susceptibility, elemental analysis, Fourier transform infrared spectroscopy spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Characterization results revealed the successful preparations of PIN/TiO2 hybrid nanocomposites. Electrokinetic properties of all the materials were determined by zeta (ζ)-potential measurements in aqueous and nonqueous media. Effects of pH, temperature, presence of various electrolytes, and surfactants on electrokinetic properties of the materials were examined. 相似文献
145.
Chiral oxazolines have been synthesized from norephedrine and pyrrole nitrile or benzoyl chloride and applied to the catalytic asymmetric Henry reactions of p-nitro aldehydes with nitromethane to provide β-hydroxy nitroalkanols in high conversion (up to 92%). The reaction was then optimized in terms of the metal, solvent, temperature, and amount of chiral ligand. The corresponding catalyst with Cu(OTf)2 and isopropanol as the solvent gave the best enantioselectivities (up to 84% ee) of the corresponding β-nitroalkanol for p-nitrobenzaldehyde. 相似文献
146.
A. Ebru Aydin 《Tetrahedron: Asymmetry》2013,24(8):444-448
Novel chiral norephedrine-based β-amino alcohol ligands containing a thiophene ring were prepared from norephedrine and substituted furan carbaldehydes (methyl- or ethyl-substituted) and used in combination with VO(acac)2 for the asymmetric oxidation of aryl methyl sulfides using H2O2 as an oxidant. Amino alcohol derived Schiff bases 4,5a–b gave higher enantiomeric excesses than amino alcohol-derived reduced Schiff based ligands 6,7a–b. Of these chiral ligands, (1S,2R)-5b and (1S,2R)-7b gave high yields (90%) with moderate to high enantioselectivities (78%, 96% ee, respectively). The oxidation of other aryl methyl sulfides with (1S,2R)-5b and (1S,2R)-7b as ligands afforded the corresponding sulfoxides in 60–89% yields and with 92–99% ee. 相似文献
147.
Serap Karaca Erol Kabil 《International journal of environmental analytical chemistry》2013,93(13):1186-1206
ABSTRACTA comprehensive multiresidue method for the analysis of 33 antibiotics from 7 prevalent classes was comparably investigated for both dairy and poultry manure samples, which can be important pollution sources for the release of antibiotics into the environment. Following salting-out-assisted extraction with acetonitrile, the antibiotics were quantified with ultrahigh-performance liquid chromatography tandem mass spectrometry without a clean-up step. By changing the composition of the mobile phase for chromatography, a pronounced signal enhancement was achieved not only for tetracyclines (TCs) but also for other groups of antibiotics in the manure samples. Although the physicochemical properties of selected antibiotics were quite different, the apparent recovery values from dairy and poultry manure samples by using an extraction solvent comprising McIlvaine buffer and ethylenediaminetetraacetic solution at pH 3 were 86–121% and 89–113%, respectively. Apparent recovery of the antibiotics was not remarkably affected by the extraction solvent over a wide range of pH values, with the exception of the recovery of TC antibiotics from poultry manure, which was in the 53–55% range at pH 8. Furthermore, the poor performance of the analytical method for a few of the antibiotics in poultry manure was correlated with high metal and organic contents of the complicated matrix. The high suppression effects of co-eluted matrix components were compensated by constructing matrix-matched calibration curves and by using internal standards. Simultaneous quantification of seven different antibiotic classes with low limit of detection values varying from 0.38 to 31 μg kg?1 for dairy manure and from 0.32 to 5.85 μg kg?1 for poultry manure facilitated their monitoring. The application of the developed analytical method to dairy, broiler and layer-hen manure samples from confined animal feeding operations showed that a wide variety of antibiotics at high concentrations were found in broiler manure. 相似文献
148.
Synthesis of novel thiophene‐based chiral ligands and their application in asymmetric Henry reaction
A. Ebru Aydin 《应用有机金属化学》2013,27(5):283-289
Novel chiral thiolated amino alcohols were synthesized from norephedrine and thiophene carbaldehydes (methyl‐ or ethyl‐substituted) and applied to the catalytic asymmetric Henry reaction of various aldehydes with nitromethane to provide β‐hydroxy nitroalkanols in high conversion (92%). The reaction was optimized in terms of the metal, solvent, temperature and amount of chiral ligand. The corresponding catalyst with Cu(OTf)2 and 2‐propanol as the solvent provided the best enantioselectivities (up to 96% ee) of the corresponding nitroalcohols for aliphatic aldehydes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
149.
150.
This paper presents a semigroup approach for the mathematical analysis of the inverse coefficient problems of identifying the unknown coefficient k(ux) in the inhomogenenous quasi‐linear parabolic equation ut(x, t)=(k(ux)ux(x, t))x +F(u), with the Dirichlet boundary conditions u(0, t)=ψ0, u(1, t)=ψ1 and source function F(u). The main purpose of this paper is to investigate the distinguishability of the input–output mappings Φ[·]:??→C1[0, T], Ψ[·]:??→C1[0, T] via semigroup theory. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献