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1.
Brian D. Hudson Ashley R. George Martyn G. Ford David J. Livingstone 《Journal of computer-aided molecular design》1992,6(2):191-201
Summary Molecular dynamics simulations have been performed on a number of conformationally flexible pyrethroid insecticides. The results indicate that molecular dynamics is a suitable tool for conformational searching of small molecules given suitable simulation parameters. The structures derived from the simulations are compared with the static conformation used in a previous study. Various physicochemical parameters have been calculated for a set of conformations selected from the simulations using multivariate analysis. The averaged values of the parameters over the selected set (and the factors derived from them) are compared with the single conformation values used in the previous study. 相似文献
2.
Brian F.G. Johnson Jack Lewis Martyn V. Twigg 《Journal of organometallic chemistry》1974,67(3):C75-C76
Photolysis of Ru3(CO)12 in the presence of donor ligands rapidly produces monomeric ruthenium species. 相似文献
3.
Martyn V. Twigg 《Transition Metal Chemistry》1993,18(2):175-178
Summary Diluting a concentrated solution of [Fe(bipy)3](ClO4)2 in DMSO causes the complex to dissociate. First order kinetics have been followed, with activation parameters of H = 26.69 ± kcal mol–1 and S = 17.1 ± 1.3 cal K–1 mol–1. Comparing rate data in neutral DMSO with those in the presence of acid provides information about the reactivity of the first formed monodentate intermediate. This is more likely to dissociate to [Fe(bipy)2-(DMSO)2]2+ than undergo ring closure and reform the parent complex than in water. In DMSO, in the presence of added 2,2-bipyridine at 30.0° C, dissociation is not complete. The reaction is first order, and rate constants increase linearly with added ligand due to an increasingly significant back reaction. Kinetic and static derived values for the third formation constant of [Fe(bipy)3]2+ agree well, and are smaller than in water. The origins of the reactivity differences in the two solvents are discussed. 相似文献
4.
Martyn S. Ray 《Adsorption》1995,1(1):83-97
This article provides a bibliographic listing of published journal papers concerned with adsorptive separations during 1992–1993. The references are taken from the 40 most important chemical engineering journals. This paper provides an update to the literature as provided in previous bibliographic papers [1, 2]. These previous papers also included membrane-type separations, however due to the number of papers and the diversity of membrane and associated processes, this material is to be published separately [3].Other bibliographic papers covering the more traditional unit operations, e.g. distillation [4], and equilibrium-staged separations in general [5, 6] have been published. Liquid-liquid extraction [7] is the subject of a separate bibliography (for 1992–1993), due to the number of publications on this topic. A bibliography detailing supercritical extraction from 1980–1993 is also to be published separately due to the current interest in this relatively new technology [8]. A complete bibliography of the chemical engineering journal literature from 1967–1993 has been published by the author [9–12]. An earlier bibliography [13] provides access to the literature prior to 1967. 相似文献
5.
Martyn A. Brown Bruce R. McGarvey Andrzej Ozarowski Dennis G. Tuck 《Journal of organometallic chemistry》1998,550(1-2)
The primary process in the reaction of hexaphenylditin with various substituted orthoquinones (Q) is shown to involve attack by the quinone at a phenyl ligand. The intermediate thus formed decomposes to yield Ph3Sn(SQ·), where S(Q·−) is the corresponding semiquinonate. Rearrangement of these species in solution gives rise to biradicals, while intramolecular electron transfer may lead to the formation and precipitation of Ph2Sn(CAT), where CAT2− is the corresponding substituted catecholate. The identification of these processes depends in part on electron paramagnetic resonance spectroscopy. The reaction of Ph3SnCl or Ph2SnCl2 with Na(TBSQ·) (TBSQ·−=3,5-di-tert-butyl-orthobenzosemiquinonate) results in the formation of Ph2Sn(TBSQ·), which can undergo redistribution and intramolecular electron transfer, so that the solution chemistry of these latter systems is similar to that of the products of the Sn2Ph6+Q reaction. 相似文献
6.
Timothy R. Baker Paul Vouros Jeevendra A. J. Martyn 《Journal of mass spectrometry : JMS》1989,24(9):723-732
Pancuronium and vecuronium are members of a series of quaternary ammonium steroids used as neuromuscular blocking agents in anesthesiology. In this study the mass spectrometric properties of these bromide salts are examined and spectral features which permit their differentiation are evaluated. The relative merits of chemical ionization and fast atom bombardment using the moving belt liquid chromatography/mass spectrometry interface have been investigated. Fragmentation pathways for both ionization methods were determined with deuterium labeling and linked-scan techniques. Cleaner spectra can be obtained via the matrix-free belt introduction system as compared to conventional fast atom bombardment. 相似文献
7.
M. Althoff W. Braunschweig F.J. Kirschfink H.-U. Martyn P. Rosskamp D. Schmitz H. Siebke W. Wallraff J. Eisenmann H.M. Fischer H. Hartmann A. Jocksch G. Knop H. Kolanoski H. Kück V. Mertens R. Wedemeyer G. Zobernig 《Physics letters. [Part B]》1984,149(6):524-532
We have determined the average lifetime of hadrons containing b quarks produced in e+e? annihilation to be . Our method uses charged decay products from both non-leptonic and semileptonic decay modes. 相似文献
8.
The use of stable carbon isotope analysis to detect the abuse of testosterone in cattle. 总被引:3,自引:0,他引:3
The use of stable carbon isotope analysis to detect the administration of anabolic steroids to cattle was investigated. Samples were extracted by solid-phase extraction on C18 cartridges. Stable isotope ratios (13C:12C) were measured by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) of the underivatised extracts. A programmed temperature vaporiser (PTV) injector was installed in the GC-IRMS system, which conferred a number of advantages. First, it allowed large volumes of sample to be injected whilst the injector liner was cool. The solvent was subsequently vented to the atmosphere prior to transfer of the sample to the GC column. Thus a significantly greater amount of sample could be presented for analysis, thereby increasing the sensitivity. Second, by this means virtually all the solvent could be removed prior to analysis. This eliminates solvent peak tailing, which can be a major problem in GC-IRMS. Finally, the PTV allowed the use of higher initial GC oven temperatures, which in turn facilitated the analysis of underivatised steroids by reducing the GC run time and improving the chromatographic peak shape. The carbon isotope composition of 5 beta-androstane-3 alpha,17 alpha-diol, the major metabolite of testosterone found in bovine bile, was measured in bile samples from untreated cattle and from cattle injected intramuscularly with testosterone or a mixture of testosterone esters. There was considerable inter-animal variation in the values obtained and there was no significant difference between samples from treated and untreated animals. However, when the isotopic composition of the metabolite was normalised with respect to that of an endogenous reference compound (cholesterol) in the same sample, the difference between treated and untreated animals become statistically significant. 相似文献
9.
Alistair P. Rendell Martyn F. Guest Rick A. Kendall 《Journal of computational chemistry》1993,14(12):1429-1439
The recently developed parallel coupled-cluster algorithm of Rendell, Lee, and Lindh [Chem. Phys. Lett., 194 , 84 (1992)] is extended to allow four-indexed quantities containing one or two indices in the virtual orbital space to be stored across the global memory of distributed-memory parallel processors. Quantities such as the double-excitation amplitudes can now be distributed over multiple nodes, with blocks of data retrieved from remote nodes by the use of interrupt handlers. As an application of the new code, we have investigated the potential energy surface of the 2-hydroxypyridine/2-pyridone tautomers. Using large basis sets, the structure of each tautomer and the transition state connecting the two minima has been determined at the SCF level. The relative energy difference and the activation energy were then redetermined using the MP2, CCSD, and CCSD(T) methods. All calculations have been performed on Intel distributed-memory supercomputers. The largest coupled-cluster calculations contained over 2 million double-excitation amplitudes. © John Wiley & Sons, Inc. 相似文献
10.
José A. Fernandes Susana S. Braga Rute A. Sá Ferreira Martyn Pillinger Luís D. Carlos Paulo Ribeiro-Claro Isabel S. Gonçalves 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):329-333
A 1:1 inclusion compound between octakis(2,3,6-tri-O-methyl)-γ-cyclodextrin (TRIMEG) and the chelate complex Eu(NTA)3·2H2O (NTA=1-(2-naphthoyl)-3,3,3-trifluoroacetonate) was prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and photoluminescence spectroscopy. The results were compared with those obtained for the corresponding native γ-CD adduct. Excitation and emission spectra were measured, and the lifetimes were determined for the Eu3+ first excited state (5D0). The results indicate the presence of only one low-symmetry environment for the Eu3+ cations in the inclusion compounds. Encapsulation of the Europium complex in the two CDs increases the quantum efficiency of the ligand-to-metal energy transfer pathway, but the efficiency of the Eu3+ sensitization was significantly higher with TRIMEG as the host molecule. This may be related with the observation that the two hosts appear to have different influences on the Eu3+ coordination environments for the guest molecule. 相似文献