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41.
Nisa V. Salim Nishar Hameed Qipeng Guo 《Journal of Polymer Science.Polymer Physics》2009,47(19):1894-1905
Blends of poly(2‐vinyl pyridine)‐block‐poly(methyl methacrylate) (P2VP‐b‐PMMA) and poly(hydroxyether of bisphenol A) (phenoxy) were prepared by solvent casting from chloroform solution. The specific interactions, phase behavior and nanostructure morphologies of these blends were investigated by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). In this block copolymer/homopolymer blend system, it is established that competitive hydrogen bonding exists as both blocks of the P2VP‐b‐PMMA are capable of forming intermolecular hydrogen bonds with phenoxy. It was observed that the interaction between phenoxy and P2VP is stronger than that between phenoxy and PMMA. This imbalance in the intermolecular interactions and the repulsions between the two blocks of the diblock copolymer lead to a variety of phase morphologies. At low phenoxy concentration, spherical micelles are observed. As the concentration increases, PMMA begins to interact with phenoxy, leading to the changes of morphology from spherical to wormlike micelles and finally forms a homogenous system. A model is proposed to describe the self‐assembled nanostructures of the P2VP‐b‐PMMA/phenoxy blends, and the competitive hydrogen bonding is responsible for the morphological changes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1894–1905, 2009 相似文献
42.
R. J. Peterson S. deBarros I. O. deSouza M. B. Gaspar Hameed Ahmed Khan Shahid Manzoor 《Zeitschrift für Physik A Hadrons and Nuclei》1995,352(2):181-189
Data for fission induced by pi meson beams from 80 to 500 MeV are presented for nuclei from Fe through Pu as measured by solid state track detectors. The general trends for binary fission withπ + are reproduced fairly well by a calculation in the ‘high excitation’ limit with standard level density and fission barrier parameters, butπ ? data are underpredicted. A universal dependence of the binary fission probabilities with the fissility (Z±1)2/A is found to be valid for both pion beam charges for all beam energies below the delta resonance. Probabilities for observing three fragments withπ + are not reproduced by a ternary fission application of the model found to work for binary fission. 相似文献
43.
The exact analytic solutions of two problems of a second order fluid in presence of a uniform transverse magnetic field are investigated. The governing equation is of fourth order ordinary differential equation and is solved using perturbation method. In the first problem we discuss the flow of a second order fluid due to non-coaxial rotations of a porous disk and a fluid at infinity. In second problem the flow of a second order conducting fluid between two infinite plates rotating about the same axis is investigated, with suction or blowing along the axial direction. For second order conducting fluid it is observed that asymptotic solution exists for the velocity both in the case of suction and blowing. 相似文献
44.
Twenty two crude ethanolic extracts from 14 indigenous medicinal plants were subjected to enzyme inhibition screening against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and lipoxygenase enzymes (LO). Three extracts showed activity against AChE, nine extracts were found to be active against BChE and four extracts inhibited the enzyme LO. The most significant inhibition activities (> or =50%) were found in extracts derived from Aloe vera (leaves), Alpinia galanga (rhizome), Curcuma longa (rhizome), Cymbopogon citratus (leaves), Ocimum americanum (leaves), Ocimum americanum (stem) and Withania somnifera (roots). 相似文献
45.
A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance. 相似文献
46.
Diego Venegas‐Yazigi Hameed Mirza A. B. P. Lever Alan J. Lough Juan Costamagna Ramn Latorre 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):e281-e282
The title complex, [Ru(C2H3N)2(C6H6N2)(C18H15P)2](PF6)2.CH4O, is the third of a series of ruthenium complexes containing two triphenylphosphine groups in a trans arrangement, o‐benzoquinone diimine and two other non‐redox active ligands to been characterized. The effect of electron donor–acceptor properties of the two non‐redox active ligands does not change the quinone arrangement for the o‐benzoquinone diimine ligand, as can be seen from the bond distances of the quinone ring. The asymmetric unit contains half a molecule of complex cation (on a twofold rotation axis), one hexafluorophosphate anion and half a molecule of methanol in a general position close to a twofold rotation axis. 相似文献
47.
Diego Venegas‐Yazigi Hameed Mirza A. B. P. Lever Alan J. Lough Juan Costamagna Andrs Vega Ramn Latorre 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e245-e246
The Ru atom in the title compound, [RuCl2{P(C6H5)3}2{C6H4(NH)2}]·1.33CH3OH·0.33CH2Cl2, shows a six‐coordinate octahedral geometry, with a trans arrangement of the triphenylphosphine groups. One and a half molecules of complex, two molecules of methanol and a half molecule of dichloromethane form the asymmetric unit, with crystallographic twofold rotation symmetry for the complex molecule in a special position. 相似文献
48.
Mirai Ohara A. Shahul Hameed Kei Kubota Akihiro Katogi Kuniko Chihara Tomooki Hosaka Shinichi Komaba 《Chemical science》2021,12(37):12383
K-ion batteries (KIBs) are promising for large-scale electrical energy storage owing to the abundant resources and the electrochemical specificity of potassium. Among the positive electrode materials for KIBs, vanadium-based polyanionic materials are interesting because of their high working voltage and good structural stability which dictates the cycle life. In this study, a potassium vanadium oxide phosphate, K6(VO)2(V2O3)2(PO4)4(P2O7), has been investigated as a 4 V class positive electrode material for non-aqueous KIBs. The material is synthesized through pyrolysis of a single metal–organic molecular precursor, K2[(VOHPO4)2(C2O4)] at 500 °C in air. The material demonstrates a reversible extraction/insertion of 2.7 mol of potassium from/into the structure at a discharge voltage of ∼4.03 V vs. K. Operando and ex situ powder X-ray diffraction analyses reveal that the material undergoes reversible K extraction/insertion during charge/discharge via a two-phase reaction mechanism. Despite the extraction/insertion of large potassium ions, the material demonstrates an insignificant volume change of ∼1.2% during charge/discharge resulting in excellent cycling stability without capacity degradation over 100 cycles in a highly concentrated electrolyte cell. Robustness of the polyanionic framework is proved from identical XRD patterns of the pristine and cycled electrodes (after 100 cycles).Highly pure K6(VO)2(V2O3)2(PO4)4(P2O7), synthesized from the oxalatophosphate precursor, demonstrates a reversible potassium extraction/insertion capacity of 59 mA h g−1 with a single discharge voltage plateau at 4.0 V at room temperature. 相似文献
49.
MUHAMMAD Naeem Ahmed IFZAN Arshad WANG Bo SHAHID Hameed BILAL Ahmad Khan KHAWAJA Ansar Yasin MUHAMMAD Moazzam Naseer 《结构化学》2014,(12)
One-pot three component reaction was used to synthesize 1,4,5-trisubstituted 1,2,3-triazole(A) from the corresponding acid chloride, benzyl azide and 1-copper(I) phenylethyne. The molecular structure was determined by single-crystal X-ray analysis. The compound crystallizes in the orthorhombic space group Pbca, a = 14.9815(14), b = 9.6496(10), c = 25.528(2) A, Z = 8. Furthermore, crystal packing demonstrated a molecular wall-like structure based on supramolecular chains of A, stabilized by CH···O, CH···Br, N···C and CH···π interactions. Molecular geometry in the ground state has been determined by density functional theory(DFT) by B3LYP/6-311G* basis set and compared with the experimental data. The computed vibrational frequencies are compared with the experimental FT-IR data and frontier molecular orbital analyses were performed at the same level of theory. Theoretical parameters are in good agreement with the corresponding X-ray diffraction values. 相似文献
50.
Numerical and analytical solutions of an Oldroyd 8‐constant MHD fluid with nonlinear slip conditions
The flow of an Oldroyd 8‐constant non‐Newtonian MHD fluid is investigated analytically and numerically. The governing equations for the flow field are derived for a steady one‐dimensional flow. The effect of constant applied magnetic field is included and its influence on the flow field is studied. The nonlinear governing equation along with nonlinear boundary conditions is solved analytically and the solution is obtained in an elegant way. Numerical solutions are also obtained using higher order Chebyshev spectral methods. The influence of various non‐Newtonian parameters and applied magnetic field is investigated. Results showing the effect of various physical parameters of the flow are presented and investigated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献