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Boron rings containing planar octa- and enneacoordinate cobalt, iron and nickel metal elements

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Science china chemistry 2008年第7期51卷 607-613页

作者： LUO Qiong School of chemistry and chemical engineering, central south university, changsha 4.0083, china School of chemistry and chemical engineering Central South UniversityChangsha 410083China

For a series of boron rings with planar hyper-coordinate 8th group transition metal atoms, singlet 1FeB8-2, multiplet kFeB9n (n = -1, k = 1; n = 0, k = 2), singlet 1CoB8n(n = -1, +1, +3), multiplet kCoB9n (n = +1, k = 2; n = 0, k = 1) and singlet 1NiB9+, the geometry structures have been optimized to be local minima on corresponding potential hyper-surfaces. The electron structures are discussed by orbital analysis and the aromaticity is predicted by nucleus-independent chemical shifts calculation at both the B3LYP/6-311+G* and BP86/6-311+G* levels of theory, respectively. The results suggest that all these structures with high symmetry planar geometries are stable and have aromatic properties with six π valence electrons.

关键词： planar hyper-coordinate transition metal DFT

Electrochemical characteristics of amorphous MgTi_xNi(x = 0,0.1,and 0.2) hydrogen storage alloys

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Rare Metals 2010年第5期29卷 486-490页

作者： LIU Suqin,ZHAO Wenjuan,HUANG Kelong,and HUANG Hongxia college of chemistry and chemical engineering,central south university,changsha 4.0083,china college of chemistry and chemical engineering Central South University Changsha China

MgTixNi （x = 0, 0.1, and 0.2） alloys were successfully prepared by mechanical alloying （MA）, and the influence of milling time on the electrochemical characteristics of the electrodes was discussed. MgTixNi alloys after 90 h milling displayed the best electrochemical performance The X-ray diffraction patterns showed that the alloy ball-milled for 90 h was amorphous with a widened diffraction peak. The charge-discharge tests indicated that these alloys had good electrochemical activation properties, and the MgTi0.2Ni alloy electrode exhibited the best cycle performance. The initial discharge capacity of the MgTi0.2Ni alloy reached up to 401.1 mAh·g^-1, and the retention rate of capacity was 31.0% after 30 cycles, much higher than that of MgNi （17.3%）. The Tafel polarization curves revealed that Ti addition could enhance the anticorrosion performance of these alloys in alkali solution, which was responsible for the ameliorated cyclic stability of these alloy electrodes.

关键词： hydrogen storage alloys titanium electrochemical properties mechanical alloying

Resolution of α-cyclohexyl-mandelic acid enantiomers by two-phase (O/W) recognition chiral extraction

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Science china chemistry 2007年第6期50卷 764-769页

作者： TANG KeWen1,2, ZHANG GuoLi2, HUANG KeLong2, LI Yuanjian3 & YI JianMin1,2 1 Department of chemistry and chemical engineering, Hunan Institute of Science and Technology, Yueyang 414000, china 2 college of chemistry and chemical engineering, central south university, changsha 4.0083, china 3 college of Pharmaceutical Science, central south university, changsha 410078, china Department of chemistry and chemical engineering Hunan Institute of Science and TechnologyYueyang 414000China college of chemistry and chemical engineering Central South UniversityChangsha 410083China

This paper presents a new chiral separation technology:two-phase(O/W)recognition chiral *** behavior of alpha-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-isobutyl tartrate in 1,2-dichloroethane organic phase and beta-CD derivatives in aqueous phase,and the influence of the kind and concentration of extractant and pH on extraction performance was *** experimental results indicate that two-phase(O/W)recognition chiral extraction is of strong chiral separation ***-^-CD,HE-beta-CD and Me-beta-CD have higher recognition ability for S-CHMA than that for R-CHMA,among which HP-beta-CD has the strongest ability;whereas,D-isobutyl tartrate has reversed recognition ability for *** the extraction system containing HP-beta-CD and D-isobutyl tartrate,e.e.% of S-CHMA in aqueous phase reached 27.6% by one stage extraction,and the distribution ratio for R-CHMA(k_R)and for S-CHMA(k_S)and separation factor(alpha)are 2.44,0.89 and 2.49,***,pH and concentration of extractant have great effects on chiral separation ***-phase(O/W)recognition chiral extraction has great significance for preparative separation of racemic compounds.

关键词： two-phase(W/0)recognition chiral extraction alpha-cyclohexyl-mandelic acid enantiomers

Drag reduction of flow boiling with polymer additives

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Journal of central south university of Technology 2001年第2期8卷 143-146页

作者： QIU Yun ren 1,CHEN Wei ping 2,SI Qin 3 (1.college of chemistry and chemical engineering, central south university, changsha 4.0083, china 2.Editorial Office of Journal of central south university, changsha 4.0083, china 3.college of chemical E 1. college of chemistry and chemical engineering Central South University 410083 Changsha China 2. Editorial Office of Journal of central south university 410083 Changsha China 3. college of chemical engineering Tianjin University 300072 Tianjin China

The drag reducing effect of polymer additive aqueous solution was investigated in flow boiling, and the polymer additives were two kinds of polyacrylamide (PAM) with relative molecular mass about 2.56×10 6 and 8.55×10 6. The frictional pressure drop was calculated according to the measured total pressure drop. The results show that the flow drag of flow boiling is reduced by adding a small amount of PAM to water when heat flux is in the range of 15.1 kW·m -2 to 47.0 kW·m -2 , when the mass fraction of PAM is higher than 2.0×10 -5 , the drag reducing effect is obvious. Drag reducing effect of PAM, whose relative molecular mass is 8.55×10 6, is slightly better than that of 2.56×10 6 at the same mass fraction, and the greater the flow rate of the additive solution, the better the effect of the drag reduction.

关键词： polymer additive flow boiling drag reduction pressure drop

Effects of Oxalic Acid Addition on the Hydrothermal Synthesis of Kaolinite

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Journal of central south university 2000年第1期12卷 34-36页

作者： LIU Su qin,HUANG Ke long (college of chemistry and chemical engineering, central south university of Technology, changsha 4.0083, china) 1. college of chemistry and chemical engineering Central South University of Technology 410083 Changsha China

Kaolinite was hydrothermally synthesized from alumina gel and silicate by dissolving alumina gel in oxalic acid before it was mixed with silicate, effects of the amount of addition on the species of synthetic products were discussed. The reaction product was characterized by X ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that analcite is the only phase of the reaction solution without oxalic acid, the proportion of kaolinite in product increases with the amount of addition, and kaolinite is the main species when the molar ratio of oxalic acid to alumina reaches 0.6∶1.0. This is because oxalic acid addition is beneficial to the formation of kaolinite through changing the coordination number of aluminium from four to six, while the mixture of alumina gel, before it was dissolved in oxalic acid with silicate interfered with the crystallization of kaolinite.

关键词： kaolinite hydrothermal synthesis oxalic acid

Preparation of insoluble β-CD polymer and its application to enantiomers and isomers separation

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Journal of central south university of Technology 2001年第1期8卷 57-59页

作者： YI Jian ming 1,TANG Kuo wen 2 (1.college of chemistry and chemical engineering, central south university, changsha 4.0083, china 2.Department of chemical engineering, Yueyang Normal university, Yueyang 414000, china) 1. college of chemistry and chemical engineering Central South University 410083 Changsha China 2. Department of chemical engineering Yueyang Normal University 414000 Yueyang China

An insoluble β-cyclodextrin polymer cross-linked with epichlorohydrin was prepared, and its structure was identified with infrared spectrum. Colloid stationary phase was prepared by dissolving the polymer in the mixed solvent of diisopropyl ether, methylene dichloride and benzene and treated for 0.5 h by ultrasonication, and then was coated on a fused silica capillary column. The optimun reaction conditions are as follows: the mole ratio of epichlohydrin to β-cyclodextrin is 12.1:1, reacting at 65 °C for 24 h. The Chromatographic performance such as column efficiency, thermal stabilities and polarity were studied, two kinds of disubstituted benzene isomers and eight pairs of enantiomers were separated on the capillary column. The results show that the β-cyclodextrin polymer is suitable for use as a capillary gas chromatographic stationary phase, and possess excellent chromatographic properties in separating enantiomers and position isomers.

关键词： insoluble β cyclodextrin polymer capillary gas chromatography enantiomer position isomer separation

Preparation and electrochemical performance of spherical Fe_3O_4 as anode materials for Li-ion batteries

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Science china(Technological Sciences) 2009年第11期52卷 3219-3223页

作者： WANG FangBin, CHEN Jie, HUANG KeLong & LIU SuQin college of chemistry & chemical engineering, central south university, changsha 4.0083, china 1. college of chemistry & chemical engineering Central South University Changsha 410083 China

Fe3O4 nano-powder was prepared by the hydrothermal method. The structure and morphology of the product were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The as-prepared powder has regularly spherical morphology, and the average size of product is about 25 nm. The possible application use of this material as the active mass of anode for rechargeable Li batteries was examined by cyclic voltammeter (CV), galvanostatic charge/*** experimental results showed that this material exhibited large specific capacity at the first cycle, and the discharge and charge capacity retention of this electrode are 37.04% and 48.76%, respectively. Furthermore, the impedance change of Fe3O4 electrode under different cycle number and potential was examined.

关键词： Fe3O4 lithium battery anode electrochemical performance

Study on the Separation of Co^(2+) from Zn^(2+) , Cd^(2+) by Anion-exchange Chromatography

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Journal of central south university 2000年第2期12卷 88-91页

作者： WANG Xin yan,ZHOU Chun shan,WANG Yan (college of chemistry and chemical engineering, central south university of Technology, changsha 4.0083, china) 1. college of chemistry and chemical engineering Central South University of Technology 410083 Changsha China

The separation of Co 2+ from Zn 2+ , Cd 2+ by anion exchange chromatography was discussed. The chromatographic column containing anion resin 201×7 which was saturated with a solution of ammonium chloride. The effects of the eluant acidity and eluant composition on the separation were investigated. The results indicate that this anion exchange chromatography is suitable to the separation of Co 2+ from Zn 2+ , Cd 2+ , and the condition of separation is simple and convenient. When the column is saturated with NH 4Cl solution (2.0 mol/L, pH=4.0), the separation can be completed effectively. Zn 2+ and Cd 2+ can also be separa ted when different eluants are used and the pure solution with high concentration of Zn 2+ , Cd 2+ respectively can be obtained ea sily.

关键词： anion exchange chromatography Zn 2+ Cd 2+ Co 2+ separation

Silylated and acetylated β-cyclodextrins for gas chromatographic stationary phases

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Journal of central south university of Technology 2001年第4期8卷 239-243页

作者： TANG Ke wen 1,2 ,YI Jian ming 2,ZHOU Chun shan 1,ZHONG Shi an 1 (1. college of chemistry and chemical engineering, central south university, changsha 4.0083, china 2. college of chemistry and chemical engineering, Yueyang Normal university 1. college of chemistry and chemical engineering Central South University 410083 Changsha China 2. college of chemistry and chemical engineering Yueyang Normal University 414000 Yueyang China

Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.

关键词： capillary gas chromatography silylated and acetylated β-cyclodextrins enantiomeric separation