检索结果-南通市图书馆

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第3期26卷 205-212页

作者： LUO Beiping REN Buye XU You ZHENG Yajie Department of chemistry and chemical engineering Hunan Institute of Science and Technology Yueyang 414000 China college of Metallurgical Science and engineering Central South University Changsha 410083 China Research Institute of Materials Science South China University of Technology Guangzhou 510640 China

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy electrode for hydrogen evolution reaction （HER）. The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 30% KOH solution containing 10% potassium sodium tartrate at 70℃ for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range （about 50 nm）, a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interruption shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.

关键词： catalytic activity surface treatment Ni-Fe-Mo-Co alloy hydrogen evolution electrodeposition

Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 101-112页

作者： LIU Rangsu, DONG Kejun, LIU Fengxiang, ZHENG Caixing, LIU Hairong & LI Jiyong Department of Applied Physics, Hunan university, changsha 410082, china college of Materials Science and engineering, Hunan university, changsha 410082, china college of chemistry and chemical engineering, Hunan university, changsha 410082, china 1. Department of Applied Physics Human University 410082 Changsha China 2. college of Materials Science and engineering Hunan University 410082 Changsha China 3. college of chemistry and chemical engineering Hunan University 410082 Changsha China

A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12 0 12 0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

关键词： liquid metal, solidification process, large-cluster configuration, evolution mechanism, computer simulation.

Effects of chemical coating with Ni on electrochemical properties of Mg_2Ni hydrogen storage alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第6期26卷 611-616页

作者： TANG Yougen SHEN Jianbin XU Yijun JIANG Jinzhi chemistry and chemical engineering School Central South University Changsha 410083 China

The effects of nickel coating on the electrochemical properties of Mg2Ni hydrogen storage alloys are presented in this paper. X-ray diffraction （XRD） and scanning electron microscope （SEM） techniques were employed to examine the crystal structure and surface morphologies of the bare and Ni-coated Mg2Ni alloys. The electrochemical properties of alloys were characterized by cyclic voltammetry （CV） and dectrochemical impedance spectroscopy （EIS）. The results showed that Ni coating not only decreased the charge transfer resistance, but also decreased the H atom diffusion resistance for Mg2Ni alloys. It was also found that Ni coating effectively improved the discharge capacity, but decreased the cycling performance of the as-synthesized Ni-coated MgzNi alloys. The discharge current has a great impact on the cycling perform- ance of the as-synthesized Ni-coated Mg2Ni alloys.

关键词： hydrogen storage alloys chemical coating cyclic voltammetry electrochemical impedance spectroscopy

Applied technique of the cemented fill with fly ash and fine-sands

在线全文

学校读者我要写书评

暂无评论

Journal of central south university 2001年第3期13卷 189-192页

作者： WANG Xin-ming,LI Jian-xiong,FAN Ping-zhi (college of Resources, Environment and Civil engineering, central south Universi ty, changsha 410083, china) 1. college of Resources Environment and Civil Engineering Central South University 410083 Changsha China

Traditional stabilization of backfilling material is done by using Portland cement. However, the high price of cement forced mining engineer s to seek cheaper binding materials. Fly ash, which is the indus- trial wast e from thermal power plant, possess the potential activity of jellification, and can b e used in cemented fill as a partial substitute for cement to reduce the fill co s t. Tests were done during the past few years in Xinqiao Pyrite Mine and Phoenix Copper Mine to determine the technology parameters and the suitable content of f ly ash. Specimens with different cement/fly/ash tailings (sands) ratios were tes ted to obtain the strength values of the fill mass based on the analyses of both the chemical composition and physical and mechanical properties of fly ash . The compressive strength of specimens with a ratio of 1∶2∶8 (cement to fly ash to tailings ) can reach 2 MPa after 90 d curing, totally meeting the requiremen t of artificial pillar and reducing the fill cost by 20%-30%.

关键词： fly ash cementing agent cemented fill replacement

Quantification of trace amounts of impurities in high purity cobalt by high resolution inductively coupled plasma mass spectrometry

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第3期26卷 286-291页

作者： XIE Hualin HUANG Kelong NIE Xidu TANG Yougen School of chemistry and chemical engineering Central South University Changsha 410083 China Department of chemistry Hunan Institute of Technology Hengyang 421008 China

A An analytical method using high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS） for rapid simultaneous determination of 24 elements （Be, Mg, A1, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn Sb, Ba, Pt, Au, and Pb） in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCI. The matrix effects because of the presence of excess HCI and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits were 0.016-1.50 ].tg·g^-1, the recovery ratios were 92.2%-111.2%, and the RSD was less than 3.6%. The method was accurate, quick, and convenient. It was applied to the determination of trace impurities in high purity cobalt with satisfactory results.

关键词： high resolution inductively coupled plasma mass spectrometry high purity cobalt trace impurities matrix effect standard addition method

Aspects of recent developments in analytical chemometrics

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2006年第3期49卷 193-203页

作者： LIANG Yizeng1,2, WU Hailong1, SHEN Guoli1, JIANG Jianhui1, LIANG Sheng2 & YU Ruqin1 1. State Key Laboratory of Chemo/Biosensing and Chemometrics, college of chemistry and chemical engineering, Hunan university, changsha 410082, china 2. Research Center of Modernization of Traditional Chinese Medicines, central south university, changsha 410081, china 1. State Key Laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical Engineering Hunan University Changsha 410082 China 2. Research Center of Modernization of Traditional Chinese Medicines Central South University Changsha 410081 China

Some aspects of recent developments in analytical chemometrics are discussed, in par- ticular the developments viewed from the angle of the research efforts undertaken in authors’ labora- tories. The topics concerned include resolution of high-order chemical data, morphological theory and methodology for chemical signal processing, multivariate calibration and chemical pattern recognition for solving complex chemical problems, and resolution of two-way chemical data from hyphenated chromatographic instruments.

关键词： chemometrics, high-order chemical data, pattern recognition, multivariate calibration and resolution.

3D-QSAR studies on glycogen phosphorylase inhibitors by flexible comparative molecular field analysis

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2007年第4期50卷 568-573页

作者： ZHOU Peng1 & LI ZhiLiang1,2 1 college of chemistry and chemical engineering, Chongqing university, Chongqing 400044, china 2 State Key Laboratory of Chemo/Biosensing and Chemometrics, changsha 410082, china 1. college of chemistry and chemical engineering Chongqing University Chongqing 400044 China 2. State Key Laboratory of Chemo/Biosensing and Chemometrics Changsha 410082 China

Canceling grids accommodating probes in comparative molecular field analysis (CoMFA), the idea of flexibleness is introduced into the CoMFA, and in combination with swarm intelligent algorithm which attempts to optimize distributions of diverse probes around drug molecules, a new 3D-QSAR method is proposed in this context as flexible comparative molecular field analysis (FCoMFA). In preliminary at-tempts to performing QSAR studies on 47 glycogen phosphorylase inhibitors, FCoMFA is employed and confirmed to be potent to exploring ligand-receptor interaction manners at active positions and thus to generating stable and predictable models. Simultaneously by an intuitive graphics regarding probe distribution patterns, impacts of different substituted groups on activities is also given an insight into.

关键词： flexible comparative molecular field analysis (FCoMFA) three-dimensional quantitative structure-activity relationship (3D-QSAR) particle swarm optimization algorithm (PSO) glycogen phosphorylase inhibitor probe distribution pattern

Standard Enthalpy of Formation of Monoclinic Ammonium Paratungstate

在线全文

学校读者我要写书评

暂无评论

Chinese chemical Letters 1999年第12期10卷 0-0页

作者： Shi Jun LIU Qi Yuan CHEN Ping Min ZHANG(1Department of chemistry, Xiangtan university, Xiangtan 411105)(2Department of chemistry, central south university of Technology, changsha 410083) Xiangtan Univ Dept Chem Xiangtan 411105 Peoples R China Cent S Univ Technol Dept Chem Changsha 410083 Peoples R China

The enthalpy of reaction for the decomposition of monoclinic ammonium paratungstate,(NH_4 )_10 H_2, W_12 O_424H_2 O(s), was measured using a HT-1000 calorimeter. From the experimentalresults, the standard enthalpy of ... 详细信息

关键词： Standard enthalpy of formation monoclinic ammonium paratlingstate calorimetry.

THE PRINCIPAL CONSTRUCTIVE PROCESS OF UNIT CELL IN Bi-BASED SUPERCONDUCTORS

在线全文

学校读者我要写书评

暂无评论

Journal of central south university 1995年第2期7卷 1-7页

作者： Gao Xlaohui Gao De Gao Yang Jiang Shufen(Department of chemistry, central south university of Technology, changsha, 410083, china ) 1. Department of chemistry Central South University of Technology 410083 Changsha China

In this paper, 2201 and 2212 phases as the corresponding precursor of forming 2212 and 2223 phases are discussed,and the constructive process of unit cell of 2201 phase is ascertained by XRD and chemical kinetics me... 详细信息

关键词： Bi-based superconducting phases reactional process construction of unit cell