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81.
A. H. K. Yousufzai A. Rasheed Khan S. Hasan Imam Z. H. Farooqui 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):381-385
The copolymerization of castor oil prepolymer (COP) was attempted with vinyl monomers in the presence of a free radical initiator at 75°C. It was found that acrylonitrile copolymerizes with COP in good yield, The copolymers were yellow brown in color and were soluble in hot dimethylformamide. The percentage composition of the copolymers was determined by the nitrogen of the copolymers. Their reactivity ratios were determined to be r1 = 0.53, r2 = 1.53. 相似文献
82.
A study of copolymerization of castor oil prepolymers (COP) with styrene has been made at 75°C using benzoyl peroxide as initiator. It has been found that good yields of copolymers (high molecular weight M n = 123,989) are obtained at a low concentration of COP. With an increasing concentration of COP in the binary mixture, copolymers with decreasing molecular weight are obtained. This is explained as due to presence of a high percentage of oxygen (from COP) in the system which is acting as a chain transfer agent. 相似文献
83.
The CH local mode overtone spectrum of benzyl chloride in the visible and NIR regions studied by laser induced thermal lens
and conventional NIR absorption is presented. The analysis shows that the −CH2Cl group is symmetrically oriented with respect to the benzene ring, thus finalizing one of the two possible conformational
models predicted by electron diffraction studies. The aryl CH bonds have a slightly larger force constant than that in benzene. 相似文献
84.
M. Yamaga B. Henderson K. P. O'Donnell F. Rasheed Y. Gao B. Cockayne 《Applied physics. B, Lasers and optics》1991,52(3):225-229
The Ti3+ ion in YAlO3 (YAP), Y3Al5O12 (YAG), and Al2O3 crystals occupies distorted octahedral sites relative to the nearest neighbour ligand ions. Such distortions are of even-parity in YAG where the zero-phonon lines in emission occur via magnetic dipole transitions. In contrast, the zero-phonon transitions occur by electric dipole processes in Ti3+:YAP and Ti3+:Al2O3 where there are odd-parity distortions from octahedral symmetry. This paper reports measurements of the zero-phonon lines of Ti3+ ions in YAP, YAG, and Al2O3 at 10 K. The zero-phonon lines of Ti3+:YAP are strongly polarized perpendicular to the tetragonal axis and those of Ti3+:Al2O3 parallel to the trigonal axis. The experimental results are shown to be in accord with a molecular orbital model of the radiative transition according to which the transition intensities derive from odd-parity ligand wavefunctions induced into even-parity ground and excited Ti3+ wavefunctions by odd-parity crystal distortions. 相似文献
85.
86.
Saify ZS Nisa M Azhar KF Azim MK Rasheed H Mushtaq N Arain MA Haider S Khanum M Ahmed W 《Natural product research》2011,25(20):1965-1968
Piperidine derivatives are reported to exhibit a variety of pharmacological activities. In this article, synthesis and aspartic protease inhibitory activity of three nitrophenacyl derivatives of N-methyl-4-hydroxy piperidine are reported. Enzyme assays showed that the attachment of a nitro group in the benzene ring plays an important role in the inhibition of plasmepsin-II of Plasmodium falciparum. The compound 1-methyl-1-(4'-nitrophenacyl)-4-hydroxypiperidinium bromide (3), consisting of a nitro group at the para position, was the most active at the concentration of 1.0?μM. The activity of the compounds was evaluated through the observed orientation and diagrammatic representation of nitrophenacyl derivatives of 4-hydroxy piperidine. 相似文献
87.
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89.
R. Z. Sayyed S. S. Shaikh S. J. Wani Md Tabish Rehman Mohammad F. Al Ajmi Shafiul Haque Hesham Ali El Enshasy 《Molecules (Basel, Switzerland)》2021,26(9)
The present study was aimed to evaluate the suitability of agro-wastes and crude vegetable oils for the cost-effective production of poly-β-hydroxybutyrate (PHB), to evaluate growth kinetics and PHB production in Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 with these carbon substrates and to study the biodegradation of PHB accumulated by these cultures. Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 accumulates higher amounts of PHB corn (79.90% of dry cell mass) and rice straw (66.22% of dry cell mass) medium respectively. The kinetic model suggests that the Pseudomonas sp. RZS1 follows the Monod model more closely than A. faecalis RZS4. Both the cultures degrade their PHB extract under the influence of PHB depolymerase. Corn waste and rice straw appear as the best and cost-effective substrates for the sustainable production of PHB from Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1. The biopolymer accumulated by these organisms is biodegradable in nature. The agro-wastes and crude vegetable oils are good and low-cost sources of nutrients for the growth and production of PHB and other metabolites. Their use would lower the production cost of PHB and the low-cost production will reduce the sailing price of PHB-based products. This would promote the large-scale commercialization and popularization of PHB as an ecofriendly bioplastic/biopolymer. 相似文献
90.
The problem of reconstructing the spatial support of an extended radiating electric current source density in a lossy dielectric medium from transient boundary measurements of the electric fields is studied. A time reversal algorithm is proposed to localize a source density from loss-less wave-field measurements. Further, in order to recover source densities in a lossy medium, we first build attenuation operators thereby relating loss-less waves with lossy ones. Then based on asymptotic expansions of attenuation operators with respect to attenuation parameter, we propose two time reversal strategies for localization. The losses in electromagnetic wave propagation are incorporated using the Debye's complex permittivity, which is well-adopted for low frequencies (radio and microwave) associated with polarization in dielectrics. 相似文献