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Adsorption and corrosion inhibition behavior of imidazole on cobalt electrodes studied by SERS and electrochemical methods

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Science china chemistry 2005年第6期48卷 497-503页

作者： GU Wei1, LIU Guokun2. REN Bin2. WU Deyin2. GU Renao1 & TIAN Zhongqun2.1. department of chemistry, College of chemistry and Chemical Engineering, Suzhou university, Suzhou 2.5006, china 2. State Key Laboratory for Physical chemistry of Solid Surfaces and department of chemistry, College of chemistry and Chemical Engineering, Xiamen university, Xiamen 361005, china 1. department of chemistry College of Chemistry and Chemical Engineering Suzhou University 215006 Suzhou China 2. State Key Laboratory for Physical chemistry of Solid Surfaces and department of chemistry College of Chemistry and Chemical Engineering Xiamen University 361005 Xiamen China

The interaction of imidazole with Co electrodes in an electrochemical system was studied by surface-enhanced Raman scattering (SERS) and electrochemical methods. The SER spectra of Co in an imidazole solution as a function of the applied potential were analyzed and the assignment of the Raman bands was made. It was found that there were three kinds of sur-face species on the Co surface in different potential regions and they were interchangeable de-pending on the potential. In a relatively negative potential region (?1.2.to ?0.9 V), imidazole was adsorbed on the surface and its orientation might change from a vertical configuration via the N-end of the pyridine ring to a tilted configuration via the C2.N3 double bond. In a more positive potential region (?0.8 to ?0.7 V), the SERS signal from the adsorbed imidazole weakened and finally disappeared, meanwhile the signal from the Co and imidazole complex strengthened gradually. At the open circuit potential (?0.6 V), we detected very strong bands from the Co ox-ides. By comparing the Tafel curves of the Co electrode in the solution without and with imidazole, we found that imidazole has a marked effect on the corrosion inhibition of the Co electrode. This result demonstrates that we may be able to reveal the complicated interaction of surface species with metal surface at the molecular level by combining the SERS and electrochemical methods.

关键词： cobalt, imidazole, inhibition, surface-enhanced Raman spectroscopy, Tafel plot.

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On the intergranular fracture behavior of high-temperature plastic deformation of 142. Al-Li alloy

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Rare Metals 2002年第1期21卷 67-73页

作者： TANGAitao WANGLingyun LIUXuefeng HUANGGuangjie CollegeofMaterialScienceandEngineering ChongqingUniversityChongqing400044China departmentofMetallicMaterials SichuanUniversityChengdu610065China

The tensile deformation hot simulation test of as-cast 142. Al-Li alloy was performed on Gleeble-1500 Thermal Simulator in the deformation temperature range from 350 to 450 ℃ and the strain rate range from 0.01 to *** tensile fracture behavior of the 142. Al-Li alloy at high temperature was studied experimently. The results show that the tensile fracture mode of the 142. Al-Li alloy at high temperature is changed from typical transgranular ductile fracture to intergranular brittle fracture with the increase of the deformation temperature and the strain rate. It is made out that the precipitation of LiH is the fundamental reason for the intergranular brittle fracture of the 142. Al-Li alloy at high temperature. The mechanism of hydrogen embrittlement of the 142. Al-Li alloy at high temperature was discussed, and it was proposed that the hydrogen embrittlement at high temperature is an integrated function of the dynamic and the static force, which enrichs the theories of hydrogen embrittlemen t.

关键词： Al-Li alloy high-temperature plastic deformation hydrogen embrittlement intergranular fracture

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Density-functional formula for strongly correlated systems

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Progress in Natural Science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1*, HAN Rushan2.and CHEN Nanxian1(1. department of Physics, Tsinghua university, Beijing 100084,{2. 2. department of Physics, Peking university, Beijing 100871,{2.) department of Physics Tsinghua University Beijing 100084 China department of Physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

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Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion

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Science china chemistry 2006年第3期49卷 246-255页

作者： ZHANG Ying1, SHAO Na1, YANG Ronghua1, LI Ke’an1, LIU Feng1, CHAN Winghong2.& MO Tian2.1. College of chemistry and Molecular Engineering, Peking university, Beijing 100871,{2. 2. department of chemistry, Hong Kong Baptist university, Hong Kong,{2. 1. College of chemistry and Molecular Engineering Peking University Beijing 100871 China 2. department of chemistry Hong Kong Baptist University Hong Kong China

A new spiropyran derivative was synthesized and first utilized in a polymericfilm-based optical sensor for zinc ion. Spiropyrans, combining the characteristics of metal bindingand signal transduction, show potential function in the design of optical chemical sensors(optodes) toward metal ions. When embedded in a plasticized poly (vinyl chloride) (PVC) membrane,the newly synthesized spiropyran derivative 1 exhibits obvious fluorescence enhancement at 630 nm inthe presence of zinc ion in aqueous solution. With the optimum condition described, the optodemembrane responds to zinc ion over a dynamic range of 4.94x10^(-7) to 4.15x10^(-4)mol·L^(-1), witha detection limit of 1.51x10^(-7) mol·L^(-1). The membrane not only displays excellentphotostability, reproducibility and reversibility, but also exhibits high selectivity toward zincion over transition metal ions including Hg^(2.), Cd^(2.), Pb^(2.), Cu^(2.), Fe^(3+) and commoncationic ions presented in the physiological fluids.

关键词： spiropyran, sensor, PVC membrane, zinc ion, fluorescent spectroscopy.

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Highly Sensitive Spectrophotometric Determination of Trace Amounts of Uranium ( Ⅵ ) with Thiocyanate-Basic Xanthene Dye-Gum Arabic Systems

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Chemical Research in Chinese Universities 1991年第2期7卷 119-123页

作者： Liu Zhongfang and Liu Shaopu (department of chemistry, South-West{2. Normal university, chongqing)

Spectrophotometric determination of molybdenum, zinc, cobalt(Ⅱ), indium, selenium (Ⅳ), iron (Ⅲ), vanadium (Ⅴ), which is based on the ion-associate complexes formed by the reaction of metal ion-thiocyanate anionic ... 详细信息

关键词： Uranium Thiocyanate-basic xanthene dye-gum arabic systems

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Analysis and Design of Cylindrical Magnetorheological Fluid Brake

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厦门大学学报（自然科学版） 2002年第S1期41卷 27-28页

作者： HUANG Jin, ZHANG Jun-qian, YANG Yan (department of Engineering Mechanics, chongqing university, {2. 400044, china)

Magnetorheological (MR) fluids consist of stable suspensions of magnetic particles in a carrying fluid such as water or silicone oils. The magnetorheological response of MR fluids results from the polarization induced in suspended particles by application of an external magnetic field. The interaction between the induced dipoles causes the particles to form columnar structure, parallel to the applied field. These chain-like structures restrict the motion of fluids, thereby increasing the viscosity and yield stress of the MR fluids. These mechanical characteristics allow for the construction of magnetically controlled device such as the MR fluids rotary brakes. However, there has been little information published about the design of MR fluid brakes. In this paper the design of the cylindrical MR fluid brake is investigated theoretically. Bingham model is used to characterize the constitutive behaviors of the MR fluids subject to an external magnetic field. The operational principle of the cylindrical MR fluid brake is presented. The theoretical method is developed to analyze the transmission properties of the torque of the cylindrical MR fluid brake. An engineering expression for the torque is derived to provide the theoretical foundations in the design of the cylindrical MR fluid brake. Based on this equation the volume and thickness of the annular MR fluids within the brake is expressed as functions of the desired ratio of torques with saturated magnetic field and without external field, the controlled mechanical power and the MR fluid material properties. The parameters of the thickness and width of the fluid in the brake can be calculated from the obtained equations when the required mechanical power level, the desired torque ratio are specified.

关键词： MR fluids brake analysis method design method

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Preliminarily Investigating the Polymorphism of Self-organized Actin Filament in Vitro by Atomic Force Microscope

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Acta Biochimica et Biophysica Sinica 2004年第9期36卷 637-643页

作者： Jun ZHANG1,2. Yuan-Liang WANG1*, Xin-Yong Chen3, Chuang-Long HE1, Chao CHENG1, and Yang CAO1 1Key Lab of Biomechanics & Tissue Engineering, chongqing university, chongqing 400044,{2. Biology department, chongqing university of Medicine Sciences, Congqing 400016,{2. 3Laboratory of Biophysics and Surface Analysis, university of Nottingham, Nottingham NG7 2.D, United Kingdom Key Lab of Biomechanics & Tissue Engineering Chongqing University Biology department Chongqing University of Medicine Sciences Laboratory of Biophysics and Surface Analysis University of Nottingham

With the atomic force microscope (AFM), we preliminarily investigated the large-scale structure of actin filaments formed in low concentration protein solution (5 μg/ml) via self-organization without the presence of any F-actin dynamic interfering factors (such as phalloidin) in vitro. It was found that the G-actin could be polymerized into ordered filamentous structures with different diameter from the slimmest filament of single F-actin to giant filament in tree-like branched aggregates. The observed polymerized actin filaments, to which our most intense attention was attracted, was discretely distributed and showed obvious polymorphism distinctly different from those in the presence of phalloidin or actin binding proteins (fimbrin, gelsolin, etc.) in previous experiments. Latter structures were mainly composed of single F-actin and/or multifilaments clearly consisting of several single F-actin. The experimental results clearly demonstrated that non-interference with the F-actin intrinsic dynamics in self-organizing could lead to the polymorphism of actin filamentous structures, and further analysis implied that the disturbance of normal F-actin dynamics by many factors could prevent the emergence of structural polymorphism, more often than not, give rise to formation of specific structures instead and different interference would bring about various particular structures under certain conditions.

关键词： actin self-organization filamentous structure polymorphism atomic force microscope

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Surface effects of monolayer-protected gold nanoparticles on the redox reactions between ferricyanide and thiosulfate

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Science china chemistry 2005年第5期48卷 424-430页

作者： LI Di1, SUN Chunyan1, HUANG Yunjie1, LI Jinghong1,2.& CHEN Shaowei3 1. State Key Laboratory of Electroanalytical chemistry, Changchun Institute of Applied chemistry, Chinese Academy of Sciences, Changchun 13002.,{2. 2. department of chemistry, Tsinghua university, Beijing 100084,{2. 3. department of chemistry, university of California, Santa Cruz, Santa Cruz, CA 95064, USA 1. State Key Laboratory of Electroanalytical chemistry Changchun Institute of Applied chemistry Chinese Academy of Sciences 130022 Changchun China 2. department of chemistry Tsinghua University 100084 Beijing China 3. department of chemistry University of California 95064 Santa Cruz Santa Cruz CA USA

Electron transfer through the self-assembled monolayers (SAMs) on gold nanopar-ticles is investigated by using the monolayer protected gold nanoclusters (MPCs) as elec-tron-transfer mediators. 3-Mercaptopropionic acid (MPA) and 11-meraptoundecanoic acid (MUA) MPCs were employed to catalyze the redox reaction between potassium ferricyanide and sodium thiosulfate. The catalytic mechanism was proposed that the MPCs act as diffusing elec-tron-mediators and electron transfers to and from the MPCs surface. Therefore the electron transfer rate through the capping layers would be proportional to the MPCs catalyzed reaction rate, which was monitored by the UV absorbance of ferricyanide. The calculated apparent rate constant was orders of magnitude smaller than that of the maximum of tunneling current, which was attributed to the splited energy level of the nanoscale particles.

关键词： electron transfer, three-dimensional self-assembled monolayers, redox reaction, electron transfer mediator, surface effect.

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An existence theorem for two point boundary value problem at resonance

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西南师范大学学报(自然科学版) 1999年第5期24卷 505-510页

作者： Wu Xingping 1,Yu\ Pei 2.Li Qingyu 3 1 department of Mathematics,Southwest china Normal {2.,chongqing 400715 2.department of Computer Science,chongqing Jiaotong College,chongqing 400074 3 department of Foundations,chongqing College of Commerce 西南师范大学数学系重庆重庆交通学院计算机科学系重庆重庆商学院基础部重庆

An existence theorem is obtained for the two point boundary value problem at resonance by the minimax methods.

关键词： the two point boundary value problem the Saddle Point Theorem the(PS)condition Sobolevs inequality

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Synthesis and crystal structure of complex of Ce(NO_3)_3 with N-(3-methyl-pyridin-2.yl)-formimidoyl-(3-methyl-pyridin-2.yl) hydrazone

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Science china chemistry 2004年第3期47卷 251-256页

作者： JIANG Yinzhi1,2.& HU Weixiao1 1. department of Pharmaceutical Science, Zhejiang university of Technology, Hangzhou 310032.{2. 2. department of Applied chemistry, Zhejiang Institute of Science and Technology, Hangzhou 310033,{2. 1. department of Pharmaceutical Science Zhejiang University of Technology 310032 Hangzhou China 2. department of Applied chemistry Zhejiang Institute of Science and Technology 310033 Hangzhou China

The reaction of 3,6-di-(3-methyl-pyridin-2.yI)-s-tetrazine (DMPTZ, II) with CeIII salt [Ce(NO3)3 · 6H2.] generates a new ligand, N-(3-methyl-pyridin-2.yl)-formimidoyl-(3-methyl-pyridin-2.yl) hydrazone (L), and forms a new complex: a mononuclear complex [Ce(L)(NO3)2.(H2.)3] · NO3 (III). Crystal data for III: space group P-1, with a = 0.7133(4) nm, b = 1.1139(2. nm, c = 1.4572.3) nm, α= 102.13(2.°, β= 99.81(3)°, γ= 91.10(3)°, Z = 2. V = 1113.6(7) nm3, μ = 2.12. mm?1 and F(000) = 630. L acts as a tri-dentate chelating ligand in III. There are 10 coordination sites around Ce3+ of III, which are respectively occupied by seven oxygen atoms (four from two nitrate anions and three from three H2. molecules) and three nitrogen atoms (all from L). The cerium atom and three chelating nitrogen atoms are coplanar. The mechanism of the metal assisted decomposition is discussed briefly.

关键词： rare earth, complex, crystal structure, synthesize, 3,6-bis (3-methyl-pyridin-2.yl)-s-tetrazine, N-(3-methyl-pyridin- 2.yl)-formimidoyl-(3-methyl-pyridin-2.yl) hydrazone.

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