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Nonlinear oscillations with parametric excitation solved by homotopy analysis method

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Acta Mechanica Sinica 2008年第3期24卷 325-329页

作者： Jianmin wen Zhengcai Cao School of Shipbuilding Engineering Harbin Institute of Technology at WeihaiWeihai 264209 China CIMS Research Center Tongji University Shanghai 200092 China

An analytical technique, namely the homotopy analysis method （hAM）, is used to solve problems of nonlinear oscillations with parametric excitation. Unlike perturbation methods, hAM is not dependent on any small physical parameters at all, and thus valid for both weakly and strongly nonlinear problems. In addition, hAM is different from all other analytic techniques in providing a simple way to adjust and control convergence region of the series solution by means of an auxiliary parameter h. In the present paper, a periodic analytic approximations for nonlinear oscillations with parametric excitation are obtained by using hAM, and the results are validated by numerical simulations.

关键词： Nonlinear oscillation Parametric excitation Series solutions homotopy analysis method

Theoretical Studies on N_2h+O Reaction

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Chemical Research in Chinese Universities 2008年第3期24卷 371-377页

作者： LU Ying-wen LU wen-cai SU Zhong-min Jinan Vocational College Jinan 250100 P. R. China State Key Laboratory of Theoretical and Computational Chemistry Jilin University Changchun 130023 P. R. China Institute of Functional Material Chemistry Northeast Normal University Changchun 130024 P. R. China

The N2h＋O potential energy profile was studied at the CCSD（T）/6-311G＋＋（df,p）//MP2/6-311G（d,p） level. Reactions associated with four intermediates（cis-hNNO, trans-hNNO, NNhO, and NNOh） were investigated. The results indicate that N2h＋O reaction toward h＋N2O is more favored than that toward N2＋Oh, consistent with previous experimental studies. The pathways for the two reactions are found to go through cis-hNNO, transition state, and finally to the products. The N2h＋O→Nh＋NO reaction was studied in detail. Product NO in such a reaction is likely to occur via cis-hNNO, followed by trans-hNNO, and finally dissociates into Nh＋NO. These results suggest that N2h＋O→Nh＋NO is an important channel in NO production.

关键词： N2h+O Nh+NO Potential energy profile

Syndiotactic Polymerization of Styrene and Copolymerization with Ethylene Catalyzed by Chiral half-sandwich Rare-earth Metal Dialkyl Complexes

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Chinese Journal of Polymer Science 2018年第2期36卷 222-230页

作者： De-Qian Peng Xin-wen Yan Shao-wen Zhang Xiao-Fang Li Key Laboratory of Cluster Science of Ministry of Education School of Chemistry and Chemical Engineering Beijing Institute of Technology

The syndiotactic polymerization of styrene（St） and the copolymerization of St with ethylene（E） were carried out by using a series of chiral half-sandwich rare-earth metal dialkyl complexes（Cp^x＊） as the catalysts. The complexes are Ln（Ch2SiMe3）2（ThF）（1-4： Ln = Sc（1）, Ln = Lu（2）, Ln = Y（3）, Ln = Dy（4）） bearing chiral cyclopentadienyl ligand containing bulky cylcohexane derivatives in the presence of activator and AliBu3. For the St polymerization, a high activity up to 3.1 × 10^6 g of polymer mol Ln^-1·h^-1 and a high syndiotactic selectivity more than 99% were achieved. The resulting syndiotactic polystyrenes（sPSs） have the molecular weights（Mn） ranging from 3700 g·mol^-1 to 6400 g·mol^-1 and the molecular weight distributions（Mw/Mn） from 1.40 to 5.03. As for the copolymerization of St and E, the activity was up to 2.4 × 10^6 g of copolymer mol Sc^-1·h^-1·MPa^-1, giving random St-E copolymers containing syndiotactic polystyrene sequences with different St content in the range of 15 mol%-58 mol%. These results demonstrate that the bulky cyclopentadienyl ligands of the chiral half-sandwich rare-earth metal complexes effectively inhibit the continued insertion of St monomers into the（co）polymer chain to some extent in comparison with the known half-sandwich rare-earth metal complexes.

关键词： half-sandwich Rare-earth metal complex Syndiotacti cpolymerization Copolymerization Styrene Ethylene

Electrochemical Synthesis and Research of Two Polymers Composed of Alternate Carbazole and Thiophene Units

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Qing Cheng Qing-zhen wen College of Science Naval University of Engineering Wuhan 430033 china

Two organic conjugated molecules composed of central carbazole and bithiophene groups were prepared via the Stille coupling reaction, conductive polymers were prepared by electrochemical method. Structure and photoelectric research of polymers were investigated. 1h NMR and 13C NMR of molecules were consistent with the theorical results, FT-IR showed electrochemical polymeric site were β-position of thiophene units. The smooth morphology and distributed holes were beneficial to improve the electrical conductivity by SEM. When applied voltage was from ?0.1 V to 1.2 V, both of the polymer films P1 and P2 showed good electrochromic performances. Compared with P1, P2 had better electrochemical stability and thermal stability due to the better coplanarity by repeated cyclic voltammograms and TGA. The P2 was a promising material in the electrochemical field, meanwhile, it showed that the monomer structure had greatly impact on the performance of polymer.

关键词： Stille reaction Cyclic voltammetry Electrochemistry polymerization Spectroelectrochemistry

Calcium isotope fractionation and its controlling factors over authigenic carbonates in the cold seeps of the northern South China Sea

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Chinese Science Bulletin 2012年第11期57卷 1325-1332页

作者： WANG Shuhong YAN wen MAGALhAES h Vitor ChEN Zhong PINhEIRO M Luis GUSSONE Nikolaus CAS Key Laboratory of Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Centre for Environmental and Marine Studies(CESAM)and Geosciences Department University of AveiroAveiro 3810-193Portugal Institut fiir Mineralogie Universitgit MiinsterMiinster 48149Germany

In this study, we analyzed stable calcium isotope results of authigenic carbonates from two cold seep areas of the Dongsha area and the Baiyun Sag in the northern South China Sea. The stable isotopes of carbon and oxygen as well as the mineral composition of authigenic carbonates were used to investigate control calcium isotope fractionation. The δ44/40Ca ratios of the southwestern Dongsha area samples ranged from 1.21‰ to 1.52‰ and the ratio of the Baiyun Sag sample was 1.55‰ of the SRM915a isotope standard. X-ray diffraction analysis showed that the carbonate samples consisted of dolomite, calcite and aragonite, with small amounts of high-Mg calcite and siderite. The δ13C values of the carbonates of the southwestern Dongsha area varied between δ49.21‰ and δ16.86‰ of the Vienna PeeDee Belemnite (VPDB) standard and the δ18O values ranged from 2.25‰ to 3.72‰ VPDB. The δ13C value of the Baiyun Sag sample was 2.36‰ VPDB and the δ18O value was 0.44‰ VPDB. The δ13C values of the carbonates of the southwestern Dongsha area revealed there is methane seeping into this area, with a variable contribution of methane-derived carbon. The sampled carbonates covered a range of δ13C values suggesting a dominant methane carbon source for the light samples and mixtures of δ13C values for the heavier samples, with possibly an organic or seawater carbon source. The δ18O values indicated that there is enrichment in 18O, which is related to the larger oxygen isotope fractionation in dolomite compared to calcite. The results of the Baiyun Sag sample exhibited normal seawater carbon and oxygen isotopic values, indicating that this sample is not related to methane seepage but instead to precipitation from seawater. The relatively high δ44/40Ca values indicated either precipitation at comparatively high rates in pore-water regimes with high alkalinity, or precipitation from an evolved heavy fluid with high degrees of Ca consumption (Raleigh type fractionation). The dolomite samples from the

关键词：氧同位素分馏碳酸盐岩控制因素南海北部冷泉中国碳稳定同位素 X射线衍射分析

Facile Syntheses of New Pyrazolo[1,5-a]pyrimidines Derivatives via Reactions of Enaminones with Aminopyrazole

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Chemical Research in Chinese Universities 2005年第6期21卷 663-667页

作者： LI Ming WANG Shu-wen wen Li-rong KE Zi-qin College of Chemistry and Molecular Engineering Qingdao University of Science and Technology Qingdao 266042 P. R. China Department of Chemistry Xinjiang Normal University Urumuqi 830054 P. R. China

Ethyl 7-aryl-2-benzyhhiopyrazolo [ 1,5-a ] pyrimidine-3-carboxylates （3a-3f） were conveniently synthesized through the reactions of enaminones with 5-amino-3-benzyhhio4-ethoxycarbonyl-1 h-pyrazole in good yields and high regioselectivity. The structures of the new compounds were fully characterized by spectroscopic measurmehts, elemental analysis and X-ray diffraction analysis. A plausible reaction mechanism for the formation of the title compounds was also presented.

关键词： Pyrazolo [ 1,5-a ] pyrimidine Enaminone Synthesis Mechanism Crystal structure

Exact Solution in Chaotic Inflation Model with Potential Minima

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Communications in Theoretical Physics 2001年第7期36卷 122-124页

作者： WANG wen-Fu Department of Industrial Automation Southwest Petroleum Institute Nanchong 637001 Sichuan Province China

Taking the cosmological expansion rate directly as a function of field , h = h( ), we present a new exact solution to Einstein's equations that describe the evolution of cosmological chaotic inflation model. The inflation is driven by the evolution of scalar field with inflation potential V( ) = λ 2 v2)2.8 ( 2- 2)*** spectral indices of the scalar density ns and gravitational wave fluctuations ng are computed. The value of ns lies well inside the limits set by the cosmic background explorer satellite.

关键词： chaotic inflation, exact solution, spectral indices

Synthesis and Crystal Structure of a Mononuclear Zn(II) Complex with Tridentate Schiff Base,Zn(C_(12)h_(18)N_2O)(NCS)_2

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Chinese Journal of Structural Chemistry 2006年第9期25卷 1031-1034页

作者： CAI wen-Xuan wen Yi-hang SU hong FENG Yun-Long Institute of Physical Chemistry Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces Zhejiang Normal University Jinhua 321004 China

The title complex Zn（hL）（NCS）2 （C14h18N4OS2Zn, Mr = 387.81, hL = N-（3-dimethyl-aminopropyl）-salicylaldimine） has been synthesized by the reaction of ZnSO4·7h2O with the Schiff base N-（3-dimethylaminopropyl）-salicylaldimine derived from the condensation reaction of 3-dimethylamino- 1-propylamine with salicyladehyde. It crystallizes in the monoclinic system, space group P21/n with a = 9.8360（8）, b = 14.930（1）, c = 12.277（1） A, β= 101.455（2）°, V= 1767.0（3） A 3, Z = 4, F（000） = 800, Dc= 1.458 g/cm^3 and ,μ（MoKα） = 1.631 mm^-1. The structure was refined to R = 0.0463 and wR = 0.1065 for 2681 observed reflections （1 〉 2σ（I））. Crystal analyses revealed that the Zn（Ⅱ） atom is coordinated by two nitrogen atoms of two NCS^-, and an oxygen atom as well as a nitrogen atom of amine from the neutral Schiff base ligand of N-（3-dimethyl-aminopropyl）-salicylaldimine to give a distorted tetrahedral geometry.

关键词： 3-dimethylamino-1-propylamine salieylaldehyde Sehiff base,

Performance of TiC coating prepared by in situ conversion of organic carbon film on 316L bipolar plate

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Journal of Iron and Steel Research International 2023年第8期30卷 1562-1573页

作者： wen-jiao Zhangl Yan-li Wang School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004GuangxiChina

TiC coating on 316L stainless steel surface is prepared by molten salt disproportionation reaction by using carbon layer converted from organic carbon solution as carbon *** Raman and morphology characterizations show that the carbon layer and TiC coating are successfully prepared on the surface of 316L stainless steel,the prepared carbon layer and 316L matrix have good adhesion,and the prepared TiC coating is smooth and *** the simulated cathodic environment of the proton exchange membrane fuel cell,the potentiostatic and potentiodynamic polarization measurements show that the TiC coating has smaller and more stable current density fluctuation than the 316L stainless steel substrate,and the electrochemical impedance test lasting for 275 h still shows better stable corrosion resistance than that of the 316L stainless steel ***,in the water contact angle and interface contact resistance tests,the TiC coating consistently maintained better hydrophobicity and lower interface contact resistance values than 316L stainless steel.

关键词： Bipolar plate Proton exchange membrane fuel cell TiC coating Disproportionation reaction Corrosion resistance