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31.
Kinetics of oxidation of L ‐cysteine by CoIII and FeIII complexes based on α‐ and γ‐diimine Schiff base ligands were studied in aqueous solution. Pairs of trans and cis isomers of the metal complexes were used in the studies. Kinetic measurements were performed at 25 °C and constant pH and ionic strength under pseudo‐first order condition, in which the concentration of cysteine was around two orders of magnitude greater than that of the metal complex. The observed rate constant was obtained by following the change in absorbance of the reaction mixture with time at a predetermined wavelength. The overall rate constant and order of the reaction with respect to cysteine and metal complex were determined. For both metal ions studied, the oxidation rate constant for the trans isomer was higher than that for the cis isomer. This was attributed to the contribution of the steric factor and the trans effect. The effects of substituents and the nature of the metal ion on the reaction rate are discussed. 相似文献
32.
A series of Zn(II)-Schiff bases I, II and III complexes were synthesized by reaction of o-phenylenediamine with 3-methylsalicylaldehyde, 4-methylsalicylaldehyde and 5-methylsalicylaldehyde. These complexes were characterized using FT-IR, UV-Vis, Diffuse reflectance UV-Vis, elemental analysis and conductivity. Complex III was characterized by XRD single crystal, which crystallizes in the triclinic system, space group P-1, with lattice parameters a?=?9.5444(2) Å, b?=?11.9407(2) Å, c?=?21.1732(3) Å, V?=?2390.24(7) Å3, D c ?=?1.408 Mg m?3, Z?=?4, F(000)?=?1050, GOF?=?0.981, R1?=?0.0502, wR2?=?0.1205. Luminescence property of these complexes was investigated in DMF solution and in the solid state. Computational study of the electronic properties of complex III showed good agreement with the experimental data. 相似文献
33.
Alqasoumi Saleh I. Alam Prawez Al-Rehaily Adnan J. Shakeel Faiyaz Abdel-Kader Maged S. 《平面色谱法杂志一现代薄层色谱法》2011,24(1):48-52
JPC – Journal of Planar Chromatography – Modern TLC - A densitometric high-performance thin-layer chromatographic (HPTLC) method for analysis of hydroquinone has been developed and... 相似文献
34.
35.
A simple method is presented to model large rigid-jointed lattice structures as continuous elastic media with couple stresses using energy equivalence. In our analysis the transition from the discrete system to the continuous media is achieved by expanding the displacements and the rotations of the nodal points in a Taylor series about a suitable chosen origin. The strain energy of the continuous media with couple stresses is then specialized to obtain shear deformation plate continua. Equivalent continua for single layered grids, double layered grids and three-dimensional lattices are then obtained. 相似文献
36.
Bojana Rosić Muhammad Sadiq Sarfaraz Hermann G. Matthies Adnan Ibrahimbegović 《PAMM》2017,17(1):869-870
In this work we present an upscaling technique for multi-scale computations based on random microstructures modelled as realisations of lognormally distributed random fields, or described by randomly distributed inclusions in a homogeneous matrix. Their corresponding coarse-scale model parameters are considered as uncertain, and are approximated by random variables, the distributions of which are obtained via polynomial chaos based Bayesian procedures in which the fine-scale energy is used as an observation. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
37.
Panda SK Al-Hajji AA Müller H Koseoglu OR 《Analytical and bioanalytical chemistry》2011,400(5):1231-1239
In the present study, we established a statistical distribution pattern of indigenous sulfur, nitrogen, and oxygen species in Arabian Heavy crude oil and its distilled fractions: naphtha, gas oil, and vacuum gas oil (VGO) using chemical derivatization with methyl iodide and subsequent characterization by positive electrospray Fourier transform mass spectrometry. It was observed that sulfur species for naphtha and gas oil were accumulated at lower double bond equivalent values and at lower carbon numbers compared to VGO, whereas crude oil encompassed a complete range of the sulfur species detected in all distilled fractions. Moreover, the use of alumina column chromatography and ligand exchange chromatography (LEC) on a palladium-bonded silica stationary phase revealed additional structural features of sulfur heterocycles in terms of condensed and non-condensed thiophenes. During LEC separation, in addition to sulfur heterocycles, interesting results were obtained for oxygen-containing compounds. Ortho-substituted alkyl phenols were separated from meta- and para-substituted alkyl phenols on a palladium-bonded silica stationary phase. 相似文献
38.
Latif U Mujahid A Afzal A Sikorski R Lieberzeit PA Dickert FL 《Analytical and bioanalytical chemistry》2011,400(8):2507-2515
Polymers as coating materials were combined with quartz crystal microbalances (QCMs) to design sensor devices for the detection
of both ionic and neutral analytes in liquid phase. The design and geometry of dual and tetraelectrode QCMs have been optimized
to reduce electric field interferences. An unusual Sauerbrey effect was observed while exposing potassium salt solution to
10- and 20-MHz QCMs, i.e. increase in the frequency shifts by a factor of seven, which is attributed to electro-acoustic phenomena.
Non-functionalized sol-gel materials were synthesized by templating with hydrophobic salt such as tetraethyl ammonium picrate.
Imprinting with these ions of low charge density leads to sensitive layers, and UV–Vis spectroscopy was used to check re-inclusion
of this analyte. In the next strategy, functionalized polyurethane for potassium ions and sol-gel materials with aminopropyl
group as ligand were generated to tune selectivity and sensitivity towards Ni2+ and Cu2+. Methacrylic acid polymers were optimized for the detection of atrazine by hydrogen bonding; double molecular imprinted polyurethane
approach was followed for pyrene recognition. Finally, these imprinted polymers were combined with tetraelectrode QCM to develop
sensor platform. 相似文献
39.
The investigation presented in this paper concerns on the computational simulation of emissions characteristics in compression ignition engine with hydrogen substitution. Combustion process has been modeled based on Equilibrium Constants Method (ECM) with MATLAB program to calculate the mole fractions of 18 combustion products when hydrogen is burnt along with diesel fuel at variable equivalence ratios. It can be observed that hydrogen substitution causes significant increase in NH3, H2, atom H emissions during rich combustion and OH, NO2, HNO3 emissions during lean combustion. As the equivalence ratio increases during rich combustion, mole fractions of HCN, CH4, CO and atom C decreases with increment of hydrogen substitution. N2, atom N and CO2 emissions decrease whereas no significant changes in O2, NO, O3 and atom O emissions throughout all equivalence ratios as hydrogen is added to the combustion. 相似文献
40.
Boubakeur Benahmed Hocine Mokhtar-Kharroubi Bruno de Malafosse Adnan Yassine 《Journal of Global Optimization》2011,49(3):365-379
In the first part of this paper, we give a survey on convergence rates analysis of quasi-Newton methods in infinite Hilbert
spaces for nonlinear equations. Then, in the second part we apply quasi-Newton methods in their Hilbert formulation to solve
matrix equations. So, we prove, under natural assumptions, that quasi-Newton methods converge locally and superlinearly; the
global convergence is also studied. For numerical calculations, we propose new formulations of these methods based on the
matrix representation of the dyadic operator and the vectorization of matrices. Finally, we apply our results to algebraic
Riccati equations. 相似文献