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331.
Charge-transfer salts [Co(C5H5)2][M(dpt)2] (M = Ni and Pt; dpt = cis-1,2-diphenylethene-1,2-dithiolate) were synthesized and crystallographically characterized. [Co(C5H5)2][Ni(dpt)2] crystallizes in the monoclinic space group C2/c with a = 25, 607(3) Å, b = 9.4151(11) Å, c = 14.407(4) Å, β = 101.373(22)°, V = 3405.3(10) Å3 and Z = 4. [Co(C5H5)2][Pt(dpt)2] belongs to the triclinic space group $ {\rm P}\bar 1 $ with a = 9.4666(11) Å, b = 13.9869(12) Å, c = 14.2652(9) Å, α = 99.983(6)°, β = 90.034(7)°, γ = 109.751(7)°, V = 1747.2(3) Å3 and Z = 2. Both structures consist of ··· D+A?D+A?D+A? ··· linear chains with the local C5 axis of the eclipsed [Co(C5H5)2]+ cation parallel to the best MS4 plane of the [M(dpt)2]? anion. Magnetic susceptibility measurements show that χM T values of the complexes [Co(C5H5)2][M(dpt)2] (M = Ni, Pd, and Pt) remain nearly constant in the temperature range 15–300 K, but decrease rapidly with further decreasing of temperature, indicating weak antiferromagnetic interactions at low temperatures. 相似文献
332.
Jia-Yuh Sheu Yeh-Long Chen Kuo-Chang Fang Tai-Chi Wang Cherng-Chyi Tzeng Chien-Fang Peng 《Journal of heterocyclic chemistry》1998,35(4):955-964
Alkylation of 6,7-difluoro-4-hydroxyquinoline-3-carboxylic acid ethyl ester with substituted-benzyl chlorides gave 1-(substituted-benzyl)-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid ethyl esters. Their treatment with piperazine or N-methylpiperazine in pyridine yielded 1-(substituted-benzyl)-6-fluoro-1,4-dihydro-4-oxo-7-(l-piperazinyl)quinoline-3-carboxylic acid ethyl esters which were hydrolyzed with aqueous sodium hydroxide and then acidified with hydrochloric acid afforded the desired 1-(substituted-benzyl)-6-fluoro-1,4-dihydro-4-oxo-7-(1-iperazinyl)quinoline-3-carboxylic acids. The 6,8-difluoro analogs were prepared similarly using 6,7,8-trifluoro-4-hydroxyquinoline-3-carboxylic acid ethyl ester as a starting material. Some of these quinolones demonstrated fairly good antibacterial activities. Among them, 6-fluoro-1-(4-fluorophenylmethyl)-1,4-dihydro-7-(1-iperazinyl)-4-oxoquinoline-3-carboxylic acid ( 7d ) and 6,8-difluoro-1-(3-fluorophenylmethyl)-1,4-dihydro-7-(1-piperazinyl)-4-oxoquinoline-3-carboxylic acid ( 8c ) are two of the best. 相似文献
333.
Shuya Chang Ming-Fa Sheu Nien-Hsi Chang 《Journal of polymer science. Part A, Polymer chemistry》1982,20(8):2053-2061
Previous investigators have indicated that stabilizers will block the transesterification catalyst in the preparation of PET by the DMT process. This was not the case when triphenyl phosphate (TPP) or Irganox 1010 was used as the stabilizer and manganous acetate as the catalyst. Stabilizers in this study included TPP, trimethyl phosphate (TMP), tetraethylammonium hydroxide (TEAOH), Irganox 1010, and Irganox 1222. Their effect on the properties of PET made by the TPA process was investigated. It was observed that TPP and TMP greatly reduced the carboxyl content of PET and that the others had little or no effect. All stabilizers lowered the diethylene glycol content of PET. The rate of polycondensation was slightly increased when a small amount of Irganox 1010, Irganox 1222, or TMP was added. Proper concentration of stabilizer should be chosen to obtain good stability and low diethylene glycol content. Among the five stabilizers studied TPP was the best with respect to carboxyl and diethylene glycol content and thermal stability. The concentration of TPP should be kept under 0.04% by weight of PET. 相似文献
334.
Yuan-chung Sheu 《Proceedings of the American Mathematical Society》1999,127(12):3721-3728
Consider an -superdiffusion on , where is an uniformly elliptic differential operator in , and . The -polar sets for are subsets of which have no intersection with the graph of , and they are related to the removable singularities for a corresponding nonlinear parabolic partial differential equation. Dynkin characterized the -polarity of a general analytic set in term of the Bessel capacity of , and Sheu in term of the restricted Hausdorff dimension. In this paper we study in particular the -polarity of sets of the form , where and are two Borel subsets of and respectively. We establish a relationship between the restricted Hausdorff dimension of and the usual Hausdorff dimensions of and . As an application, we obtain a criterion for -polarity of in terms of the Hausdorff dimensions of and , which also gives an answer to a problem proposed by Dynkin in the 1991 Wald Memorial Lectures.
335.
Sung PJ Pai CH Hwang TL Fan TY Su JH Chen JJ Fang LS Wang WH Sheu JH 《Chemical & pharmaceutical bulletin》2008,56(9):1276-1281
Chemical investigations on the sea whip gorgonian coral Junceella juncea have led to the isolation of five new 8-hydroxybriarane diterpenoids, junceols D-H (1-5). The structures of briaranes 1-5 were determined on the basis of spectroscopic methods and the methylenecyclohexane rings were found to exist in boat form in these new diterpenoids. Junceols D (1) and F-H (3-5) exhibited cytotoxicity toward CCRF-CEM and DLD-1 tumor cells and junceols E-H (2-5) displayed weak inhibitory effects on superoxide anion generation by human neutrophils. 相似文献
336.
Hsin‐Yu Huang Huey‐Min Wang Rei‐Sheu Hou Hui‐Ting Cheng Ling‐Ching Chen 《中国化学会会志》2008,55(6):1204-1207
The task‐specific ionic liquid (TSIL) and 1‐n‐butyl‐3‐methylimidazolium thiocynanate, ([bmim]SCN) were used as the medium as well as the reactant for the synthesis of α‐thiocynanatoketones by the reaction with α‐sulfonyloxy aryl ketones. Significant rate enhancements and improved yields have been observed. 相似文献
337.
Hansda Samrat Pandit Swapan K. Sheu Tony W. H. 《Journal of Thermal Analysis and Calorimetry》2022,147(12):7007-7029
Journal of Thermal Analysis and Calorimetry - In this paper, we have conducted a numerical investigation to investigate thermal and solutal performances of thermosolutal mixed convection flow in a... 相似文献
338.
A series of dimeric twin liquid crystals derived from symmetric heterocyclic benzoxazoles 1a-1f exhibiting single smectic C phase are reported. All benzoxazoles were prepared by condensation of 2-aminophenols with benzaldehydes and then followed by subsequent intramolecular cyclization. The mesomorphic properties were investigated by DSC and POM, and the structure of the mesophases was confirmed as smectic C phases by powder XRD. The formation of mesophases was attributed to the weak dipole force induced by donor-acceptor interaction (D→A). A monolayer conformation was proposed based on the powder XRD data. A value of aspect ratio d/l=0.80-0.92 was calculated from d-spacings and the molecular lengths. By contrast, the odd-even effects by a value of entropy changes ΔSSmC→I/R=2.00-6.50 showing odd-even effect for the transition of SmC→I phases were also associated in twin system. 相似文献
339.
This paper investigates an integrated freeway traffic management system, which coordinates both dynamic toll pricing and ramp control strategies for the purpose of dynamic freeway congestion management. The proposed integrated dynamic toll-ramp control methodology is built mainly on the principles of stochastic optimal control approaches, involving two developmental procedures. First, through detector configurations and system specification, a discrete-time nonlinear stochastic system is formulated to characterize the time-varying relationships of system states, control variables, and traffic data. Then, by employing the extended Kalman filtering technology, a stochastic optimal control based algorithm is proposed to execute the integrated dynamic toll and ramp control mechanism. With the aid of the Paramics microscopic traffic simulator, numerical studies under various simulated freeway congestion scenarios are conducted. Corresponding numerical results demonstrate the applicability of the proposed methodology in response to diverse freeway traffic congestion phenomena, and its relative advantages in improving both the average travel time and hourly throughputs by 16.4% and 16.5%, respectively. 相似文献
340.
Wen‐Fa Kuo Chun‐Yen Chiu I‐Tzu Lin Shu‐Ya Sheu Kao‐Hung Lm Mou‐Yung Yeh 《中国化学会会志》2000,47(5):1171-1176
The acidic decomposition of 4‐acetylsydnones arylhydrazones 2 results in the formation of 4‐arylhydrazo‐1,2‐pyrazolin‐5‐ones 3 and 4‐arylamino‐1,2,3‐triazoles 4 , respectively. The reactions of 4‐acetylsydnones 1 with arylhydrazines 5 afford compounds 3 as the only products in the absence of solvent. 相似文献