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排序方式: 共有91条查询结果,搜索用时 31 毫秒
1.
Organic phase conversion of bulk (wurtzite) ZnO to nanophase (wurtzite and zinc blende) ZnO 总被引:1,自引:0,他引:1
Lauren P. Snedeker Aditi S. Risbud Ombretta Masala Jin Ping Zhang Ram Seshadri 《Solid State Sciences》2005,7(12):1500
We describe the all-organic phase conversion of bulk commercial ZnO in the wurtzite modification to sub-30 nm ZnO that we find to be partially in the zinc blende [, a=4.568(3) Å] modification. The conversion involves refluxing ZnO in 2,4-pentanedione (acetylacetone) at 413 K to form the zinc 2,4-pentanedionate, which is decomposed by heating at 573 K in an appropriate high-temperature solvent such as dibenzylether to form nanophase ZnO. This nanophase, partially zinc blende ZnO can also be obtained in a single step by heating commercial zinc 2,4-pentanedionate in refluxing dibenzylether. Thermodiffractometry suggests that the conversion of zinc blende ZnO to wurtzite ZnO commences near 650 K. 相似文献
2.
Perchloric acid supported on silica gel acts as an excellent reagent system in converting glucals into 2,3-unsaturated-O-glucosides in good to excellent yields in short reaction time with good alpha selectivity. Primary, secondary, and allylic alcohols, phenols, and thiols react with 3,4,6-tri-O-acetyl glucal with equal ease. In addition to this, a chiral furan diol is obtained from unprotected D-glucal or D-galactal in good yields. 相似文献
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Novel Copolymers of Styrene and Alkoxy Ring‐Substituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides
Gregory B. Kharas Xue Tian Adam C. Hermsen Aditi S. Jani Larissa I. Kozij Emira Hadziahmetovic 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1485-1492
Electrophilic trisubstituted ethylene monomers, alkoxy ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC6H4CH?C(CN)CON(CH3)2 (where R is 2‐OCH3, 3‐OCH3, 4‐OCH3, 2‐OCH2CH3, 3‐OCH2CH3, 4‐OCH2CH2CH3, 4‐OCH2CH2CH2CH3), were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ACBN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C NMR, GPC, DSC, and TGA. High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range. 相似文献
5.
Amongst various carbon sources, xylan was found to be the sole inducer of endoxylanase production by Penicillium janthinellum MTCC 10889 in submerged cultivation. Endoxylanase synthesis by a xylan induced culture was initially repressed after a simultaneous addition of xylose, probably by the inducer exclusion mechanism, but it was resumed and achieved its highest level at a much later stage of growth (at 120 h). Xylose added after 30 h of growth cannot exert its full repressive effect. Although glucose was proved to be a more potent repressor than xylose, supplementation of salicin, an alcoholic β-glycoside containing d-glucose, with pure xylan resulted in an about 3.22 fold increase in the enzyme synthesis at 72 h followed by constant high production of the enzyme at least until the 144th h of growth. Inducing capacity of salicin in a xylan induced culture was significantly reduced when it was added after 30 h of growth. Addition of salicin and xylan help to partially overcome the repressive effect of xylose and glucose. Failure of salicin in recovering the endoxylanase synthesis in actinomycin D and cyclohexamide inhibited the xylan induced culture indicating that salicin cannot initiate the de novo synthesis of the enzyme. 相似文献
6.
Amarendra Patra Apurba K. Mukhopadhyay Alok K. Mitra Aditi K. Acharyya 《Magnetic resonance in chemistry : MRC》1981,15(1):99-101
Some carbon-13 NMR signal assignments of diazepam, flurazepam, clonazepam and chlordiazepoxide have been revised and the assignments of nitrazepam are reported. The assignments of the various resonances were made by considering the changes in chemical shifts produced by the change of substituents and also by comparison with the chemical shifts of model compounds. 相似文献
7.
We consider the capacity of classical information transfer for noiseless quantum channels carrying a finite average number of massive bosons and fermions. The maximum capacity is attained by transferring the Fock states generated from the grand-canonical ensemble. Interestingly, the channel capacity for a Bose gas indicates the onset of Bose-Einstein condensation, by changing its qualitative behavior at the criticality, while for a channel carrying weakly attractive fermions, it exhibits the signatures of Bardeen-Cooper-Schrieffer transition. We also show that, for noninteracting particles, fermions are better carriers of information than bosons. 相似文献
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An interaction quench in a Luttinger liquid can drive it into an athermal steady state. We analyze the effects on such an out of equilibrium state of a mode coupling term due to a periodic potential. Employing a perturbative renormalization group approach we show that even when the periodic potential is an irrelevant perturbation in equilibrium, it has important consequences on the athermal steady state as it generates a temperature as well as a dissipation and hence a finite lifetime for the bosonic modes. 相似文献
10.