Mar 2008, Volume 3 Issue 1

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  • BAI Chenyan, FENG Linlin, ZHANG Xingyuan, DAI Jiabing, GE Zhen, CHAO Jing
    A series of polyurethanes modified by polysiloxane (Si-PU) were synthesized based on 2,4-toluene diisocyanate (TDI), dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS), polytetramethylene glycol (PTMG) and 1,4-butanediol (BDO). Fourier transform infrared spectroscopy analysis showed that DHPDMS had been incorporated into the polyurethane chains. With the increase of DHPDMS content, the water contact angle increased while the surface tension decreased. As the DHPDMS content increases above 5%, both the contact angle and the surface tension tend to approach a constant. The contact angle increases with increasing temperature, and it tends to approach a constant when the temperature is higher than 50°C. The result indicates that Si-PU exhibits good surface and mechanical properties when the DHPDMS content is 5%.
  • SHEN Zhiquan, NI Xufeng, YANG Jianjiang
    The rare earth Schiff base complex Nd(H2Salen)2Cl32C2H5OH was synthesized by a simple and convenient method and characterized by IR and elemental analysis. The catalyst system composed of Nd(H2Salen)2Cl32C2H5OH/Al(i-Bu)3/CCl4 is effective for the polymerization of styrene (St). The optimum conditions are as follows: [St]/[Nd] = 1000, [CCl4]/[Nd] = 9, [Al]/[Nd] = 30, and polymerization at 50°C for 20 h. The resulting polystyrene was characterized by NMR and GPC. The results of NMR show that the polymer obtained had a stereoregularity with 52.3% isotacticity and 47.7% syndiotacticity without any random structure.
  • ZHANG He, YANG Biao
    A single-sheet bipolar membrane was synthesized via photografting polymerization of an acrylic acid cation exchange layer onto the surface of a commercial homogeneous anion exchange membrane with benzophenone (BP) as the main initiator, diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) and 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) as co-initiators and divinylbenzene (DVB) or neopentylene glycol diacrylate (NPGDA) as crosslinking agent. It was found that when benzophenone was used as single initiator and the crosslink agent is absent, the grafting degree (Dg) increases with the prolongation of irradiation time. The grafting degree reaches a maximum at 60 seconds reaction time when the crosslinking agent is added, and the grafting degree is higher when using NPGDA instead of DVB as crosslinking agent. The grafting degree increases as the composite initiator system is used. When polymerization was initiated by BP and TPO, and the dosage of NPGDA was 2.5% mol concentration of monomer, the grafting degree reaches 30.1%.
  • YANG Fan, YANG Xiurong
    Lipopolysaccharide (LPS) is a major component of the outer membrane of all gram-negative bacteria. It interacts with some biomolecules and triggers a toxic reaction. In this paper, we studied the interaction between LPS from Salmonella Minnesota and some biomolecules using a surface plasmon resonance (SPR) biosensor. Biomolecules were immobilized on a CM5 sensor chip using the amino coupling method and LPS was injected over the immobilized surfaces. The affinity constant KA of LPS with serum albumin, hemoglobin, chitosan and lysozyme was 2.36 × 107, 2.03 × 108, 7.58 × 106, 2.82 × 104 L·mol-1, respectively. However, LPS could not interact with ferritin.
  • LI Ziheng, ZHOU Xiangdong, LI Zhiyou, XU Shuang
    CdS semiconductor nano-films were grown on ITO glass substrates by means of chemical bath deposition (CBD), with Cd(NO3)2 as Cd ion and (NH2)2CS as S ion sources. The concentration of Cd ions, deposition temperature, deposition time and post-treatment temperature have an impact on the formation of CdS nano-films. UV-vis absorption spectrum and atomic force microscope (AFM) images indicated that the change of concentration and post-treatment temperature may adjust the band-gap of CdS to obtain stable, homogeneous and compact films. Formation mechanism of the crystal nucleus and CdS film was also discussed. Active sites on the surface of ITO are critical to the formation of the crystal nucleus and a uniform and compact CdS nano-film. The active site and crystal nucleus are formed due to the comprehensive effect of electricity, thermodynamics and chemistry.
  • WANG Bing, NA Liyan, ZHANG Fengjie, NING Guiling
    The preparation, X-ray structure and magnetic properties are presented for a new mixed-valence tetranuclear manganese complex that functions as a single-molecule magnet (SMM): [Mn4(CF3COO)4(hmp)6], where hmp- is the anion of 2-(hydroxymethyl) pyridine and is a N,O bidentate chelate. The compound crystallizes in a monoclinic system, space group P21/c (No. 14) with unit cell parameters a = 13.663(3) Å, b = 14.705(3) Å, c = 14.734(3) Å, ? = 98.51(3)°, V = 2927.6 Å3 and Z = 2. The structure of the complex shows a novel coordination of the trifluoroacetate (TFA) anions, with one anion acting as a monodentate ligand while the second one coordinating through both oxygens to the same Mn center. Direct current magnetic susceptibility measurement in the 2–300 K temperature range supports a high-spin ground state. The presence of a frequency-dependent alternating current susceptibility signal indicates that the individual molecule is acting as magnet.
  • LI Jingsheng, ZHANG Xiaolei, PAN Mingwang, XING Shengnan
    An ionomer-type of polyurethane (PU) emulsion was prepared from toluene diisocyanate (TDI), polypropylene glycol (PPG) and dimethylol propionic acid (DMPA) following a self-emulsification process. The modified poly(vinyl chloride) (PVC) emulsion resin was obtained by in situ emulsion copolymerization using the PU as seeds in an autoclave. The effects of PU molecular weight on the mechanical properties and thermal stability of the PU/PVC materials were investigated. The composite latex particles and composite materials were determined and characterized using a laser particle size analyzer, transmission electron microscopy or scanning electron microscopy. The study results showed that the PU/PVC hybrid emulsion particles possess a core/shell structure. When the general mechanical properties of the composite materials increase, the thermal stabilities decrease a little. The tough fractures on the surface of the PU/PVC composite sample following impact are quite obvious.
  • XIE Jiankun, YUE Qinyan, YU Hui, YUE Wenwen, LI Renbo, ZHANG Shengxiao, WANG Xiaona
    Activated carbon was prepared from the sewage sludge of municipal wastewater treatment plant by chemical activation (activation reagent is ZnCl2) and was used for the adsorption of dye (reactive brilliant red K-2BP). The impact of adsorbent amount, adsorption time and pH value on adsorption effect, the adsorption kinetics, and the adsorption thermodynamics were discussed according to batch adsorption tests. The results indicated that the activated carbon developed from sewage sludge (ACSS), which was mesoporous, possessed opened porous structures. The iodine number of the ACSS was 326 mg·g-1. The rate of achievement was 51.31%. The BET surface area was 298 m2·g-1 and the contents of heavy metals in the leachate didn’t exceed the contents limit. The adsorption kinetics of reactive brilliant red K-2BP on the ACSS was accorded with the two-step kinetics rate equation and pseudo-second-order kinetics equation. Compared to the Freundlich isotherm equation, the Langmuir isotherm equation showed better applicability for the adsorption. The adsorption which was favorable was an endothermic (enthalpy ?H > 0) and spontaneous (free energy ?G < 0) process and was accompanied by an increase in entropy (?S > 0).
  • BAI Yingkun, LIU Xiaoxuan, JING Yanni
    Controlled/living photopolymerization of methyl methacrylate (MMA) in miniemulsion mediated by 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy (HTEMPO) was carried out at ambient temperatures. MMA miniemulsion was prepared by using an anionic surfactant with cetylalcohol as a co-stabilizer. The photopolymerization led to stable lattices and they were obtained with no coagulation during synthesis and no destabilization over time. It was found that the obtained MMA homopolymers exhibited relatively narrow molecular weight distribution (PDI = 1.27 - 1.36) which was characterized by GPC. The plots of number-average molecular weight in (Mn) vs. conversion and ln([M0]/[M]) vs. time both were linear indicating that the reaction was a controlled/living free radical polymerization.
  • YU Liqiu, HE Liang, ZHANG Shufen, YANG Jinzong
    According to the Ullman reaction mechanism, the synthesis of 1,5-di(o-anisidino)anthraquinone was achieved by the multiphase reaction of 1,5-dichloroanthraquinone in xylene and o-anisidine in the presence of copper metal powder and potassium acetate. The effects of various factors on the reaction, such as the dosages of xylene and catalyst, molar ratios of raw materials, and reaction times were investigated. When the molar ratio of 1,5-dichloroanthraquinone to o-anisidine and potassium acetate is 1:10:2.5 and the catalyst dosage based on 1,5-dichloroanthraquinone is 5.3%, the conversion of 1,5-dichloroanthraquinone is 97.8% and the yield of 1,5-di(o-anisidino)anthraquinone is 80.6% after reflux for 10 h. Under these conditions, the recovery of the solvent is 86.0%. The target compound was identified by MS, 1H NMR, IR and DSC.
  • JI Min, SHI Qiaocui, WANG Sufen, ZHU Bin
    The electrochemical behavior of ciprofloxacin (CFX) and its interaction with the natural calf thymus DNA (ctDNA) is studied by using pulse difference voltammetry on a carbon electrode. CFX shows a well-defined oxidative peak at+ 0.88 V. As a result of reaction with ctDNA,the oxidative peak of CFX decreased markedly. According to the electrochemical equation deduced in this paper, the binding constant of 1.36 × 105 (mol/L)-1 and the binding size of 1.94 (base pairs) of CFX with ctDNA were obtained by nonlinear fit analysis of the electrochemical data. The mechanism of the interaction was explored.
  • ZHANG Honglin, KONG Zhe, YAN Yongmei, YU Li, LI Zhen
    The critical micelle concentration (CMC) and the thermodynamic function of the anionic surfactant, sodium laurate (SLA) and sodium dodecyl sulfate (SDS) in the N,N-dimethyl acetamide (DMA)/long-chain alcohol systems were studied using titration microcalorimetric method. The power-time curves of SLA and SDS in the presence of a long-chain alcohol (n-heptanol, n-octanol, n-nonanol, n-decanol) in the DMA medium were determined. Then, from the curves, the critical micelle concentration (CMC) and the thermodynamic standard formation functions (?H?m, ?G?m and ?S?m) were obtained through thermodynamic theories. The relationships between temperature, alcohol’s carbon number, concentration and thermodynamic properties were discussed. For SLA or SDS in a DMA solution, under the same concentration of alcohol, the values of CMC, ?H?m and ?S?m increase, while the values of ?G?m decrease with the increase of temperature. Under the same condition of identical temperature and alcohol concentration, the values of CMC, ?H?m, ?G?m and ?S?m decrease with the increase of the alcohol’s carbon number. In the presence of the same kind of alcohol, the values of CMC and ?G?m increase, but the values of ?H?m and ?S?m decrease with the concentration increases in alcohol series at the same temperature.
  • ZHANG Xinxiang, YANG Xiao, HUANG Youyuan, ZHOU Henghui, CHEN Jitao
    LiCo0.2Ni0.4Mn0.4O2, as the cathode material for lithium ion batteries, was modified by TiO2-coating. The effect of TiO2-coating on the structure and electrochemical performance of LiCo0.2Ni0.4Mn0.4O2 was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and galvanostatic charge-discharge tests. The results suggest that a small amount of TiO2-coating does not change the crystalline structure, but considerably improves the electrochemical performance of LiCo0.2Ni0.4Mn0.4O2 in terms of capacity delivery and cyclability. XPS measurements confirm that the improved electrochemical performance is most possibly attributed to a decrease in interaction between the layered material and non-aqueous electrolyte during the charge-discharge processes.
  • LU Yan, LIU Guosheng, LIU Yi, RAN Zhilin, WANG Hailei, SHEN Ping
    Biological effect of rare-earth lanthanum nitrate on the growth of Escherichia coli B was studied using the calorimetric method. There were exceptional changes on the growth thermogenic curves for high concentrations of lanthanum nitrate. For example, the peak high, the total quantity of heat (Q) of cultures and the growth rate constants (k) are evidently increased when compared with normal E. coli B cultures. When the concentration of lanthanum nitrate was at 300 mg/L and 500 mg/L, the Q of the cultures reached 3.89 and 2.54 times of normal cultures, respectively. The survivability of cells and the biomass of the cultures were measured using biological methods and the results show that the growth and multiplication of cells were inhibited and that the biomass decreased at high concentration of lanthanum nitrate. These revealed that the inhibiting cells discharged more quantity of heat than the normal growing cells. We named this phenomenon as “eruption of heat”. It was suggested that the mechanism for the eruption of heat was that La3+ ion damages the outer cell membrane and increases its permeability and the proton-electron potential energy across the cell membrane was reduced or couldn’t even be initiated. Energy could not be translated into ATP effectively in the course of oxidative phosphorylation resulting in heat release. So, the growth of the cells was inhibited due to scarceness of energy ATP.
  • TANG Yu, ZHANG Yuanming, YANG Jun, DU Biying, LI Lingang
    ZnS hollow nanospheres with holes were prepared by reacting ZnSO4 with H2S, the sulfide source formed in the reaction of CS2 with ethylenediamine, 1,3-propylenediamine, butylamine or 2-(2-aminoethylamino) ethanol, which also acted as a template agent, at 50°C under agitation. The shape, particle size of about 100–850 nm and hole size of about 150–600 nm of ZnS hollow nanospheres with holes were shown by SEM and TEM images. These ZnS nanospheres with ? cubic ZnS phase and composed of 2–5 nm nanocrystals were characterized by XRD and HRTEM. The blue shift of maximum absorption in UV-vis displayed the effect of quantum size. The two amino groups of amine templates reacted favorably with Zn2+ to form uniform and relatively smooth ZnS nanospheres with holes, while hydroxyethyl played a disadvantageous role. A reasonable mechanism of hole formation by H2S rushing out is suggested.
  • SUN Dan, ZHAO Jili, HAN Zhaorang, SONG Qiang, WANG Ying
    Fe3O4 magnetic nano-particles were prepared by a co-precipitation method and were modified using oleic acid. Then, the cross-linked magnetic composite microspheres containing a carboxyl group were prepared by using an improved emulsion polymerization with divinylbenzene (DVB) as the cross-linking agent. The composite microspheres comprised the Fe3O4 magnetic nano-particles as cores and the copolymer of styrene and acrylic acid as shells. The morphology and structure of the composite microsphere were characterized by FT-IR, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS) and so on. The results show that the composite microspheres were well dispersed in emulsion with uniform sizes and carboxyl groups on their surface. They were cross-linked and stable in 1 mol/L of HCl and DMF.
  • HOEGER Sigurd, CHENG Xiaohong
    The synthesis of the first two arylenealkyne conjugated macrocycles containing a long alkylene bridge via Glaser coupling of template-directed tetraacetylenes was reported. Tetraacetylene intermediates with complex structures were constructed rapidly via quadruple Hagihara coupling of monoprotected bisacetylenes to appropriate tetraiodides and subsequent desilylation. The characterization of such compounds was carried out by NMR, GPC and UV-Vis spectra. Unfortunately, the two compounds were not liquid crystals and had no biaxial nematic mesophase character as expected.
  • YANG Yueheng, ZHANG Hongfu, XIE Liewen, WU Fuyuan
    This paper reports the measurement of the Neodymium isotopic composition by Neptune Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) over the last two years. Although there is concomitant Cerium in the chemical separation process, this has no significant influence on the Neodymium analysis. As for the sample containing small amounts of Samarium (Sm/Nd < 0.04), direct calibration for isobaric interference and mass discrimination by the exponential law can be obtained by assuming that Samarium mass discrimination is the same as that of Neodymium. Geological samples after traditional chemical separation were measured by Neptune MC-ICP-MS and Thermal Ionization Mass Spectrometry (TIMS) respectively. The results show that Neptune MC-ICP-MS can measure Neodymium isotopic composition as precisely the TIMS does and is even more effective and less time-consuming than the TIMS Method.
  • CHEN Ting, SHI Xuetao, XING Yajuan, ZHANG Guangcheng
    A CaCO3 filler was treated by generally used coupling agents and a special one - ethylene-octene copolymer (POE)-g-maleic anhydride (MAH). Fourier transform infrared spectroscopy (FTIR) results show that the special coupling agent POE-g-MAH, in a chemical reaction with CaCO3, can produce an interfacial layer stronger than simple physical adhesion attained with usual coupling agents. Inverse gas chromatography (IGC) was used to investigate the surface free energy of CaCO3 after surface modification and to optimize the monolayer content of coupling agents. Based on the IGC results, it can be deduced that the monolayer cover is around 1.9% for CaCO3 treated with a titanate coupling agent. Scanning electron microscope (SEM) observation results show that the separated morphology existed in the ternary composites containing CaCO3 after surface treatment with coupling agents, whereas the core-shell morphology was obtained in the ternary composites with POE-g-MAH. The encapsulation of the CaCO3 filler treated with POE-g-MAH was caused by the strong chemical reaction between the elastomer and CaCO3 particles.
  • Haixin BAI, BAI Haixin, YANG Cheng, YANG Xiurong
    This work attempts to calculate the binding-site number using fluorescence spectroscopic method with bovine serum albumin (BSA) and Indo-1 as protein and ligand models, respectively. The method for calculating the binding-site number in BSA for Indo-1 was developed based on the relationships between changes in Indo-1 fluorescence intensity and the analytical concentration of BSA. The interaction between BSA with Indo-1 was investigated comprehensively using fluorescence techniques as well as fluorescence resonance energy transfer, and the thermodynamic parameters were calculated according to the effect of enthalpy on temperature. Three binding sites in BSA for Indo-1 were revealed, and the distances from Trp212 in BSA to the three binding sites were 2.93, 2.57 and 2.40 nm, respectively. It was also proven that Indo-1 embedded into the three hydrophobic cavities of BSA by hydrophobic association. This paper provides a reference on calculating the binding-site number in proteins for ligands and studying their interactions by fluorescence spectroscopic methods. In fluorescent quenching experiments, fluorescence changes were automatically recorded in real time by combining the Microlab 500 Series Dispenser and PTI fluorescence apparatus.
  • MI Zhentao, SU Xueli, WU Yulong, LIU Qingshan
    Solvents have an important effect on the epoxidation of propylene catalyzed by TS-1. The experimental results show that, in different solvents, the catalytic activity of epoxidation is in the following order: methanol > 2-propanol > 2-butanol > acetonitrile > acetone > tetrahydrofuran. Based on the reaction mechanism, the effects of solvents on the epoxidation were studied from eight aspects, which included the electronic effect, the steric effect, the polarity of solvent, the effect of solvent on sorption and diffusion of reactant, the oxidation of alcohol, the etherification of PO, the deactivation of TS-1 and the solubility of propylene in the solvents. The electronic effect, steric effect and the polarity of solvent were considered to be the main aspects. This work may provide theoretical guidance for choosing solvents for these kinds of reactions and also may serve as basis for further industrialization.
  • LIU Xing, WANG Yalou, WU Guanzhong, LI Jiangchuan, WU Xiaoyan
    Based on the SAR (structure activity relationship) of TZDs (thiazolidinediones), 3-methyl-1-phenyl-2-pyrazoline-5-one was selected as a substitute for TZD. Compounds of 3-methyl-1-phenyl-4-{4-[(5-methyl-2-phenyloxazol-4-yl)methoxy]benzylene(benzyl)}-2-pyrazol-5-one were designed and synthesized to find some more hypoglycemic active agents and further investigate the SAR of this class of compounds. Butanedione monoxime reacted with (substituted) benzaldehyde via cyclization and chlorination to give 4-(chloromethyl)-5-methyl-2-phenyloxazole derivatives, which condensed with 4-hydroxybenzaldehyde or vanillin, and was followed by the Knoevenagel reaction with 3-methyl-1-phenyl-2-pyrazol-5-one to give compounds Ia–Ih. Compounds Ia–Ih were hydrogenated with Pd–C to give IIa–IIh, and their hypoglycemic activity was evaluated with a glucose oxidase kit and insulin load test on normal mice. Sixteen new target compounds were synthesized. All the compounds were characterized by 1H NMR, IR, MS and elemental analysis. The preliminary pharmacological tests show that the compounds have good hypoglycemic activity and can enhance the action of insulin, especially Ib, Id and If.