Jun 2008, Volume 3 Issue 2

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  • CHEN Lin, CHEN Lin, WU Bolin, HE Xiaoyi
    During the experiment of preparing ITO (Indium Tin Oxide) nanopowder, a new complex salt crystal K3[InCl6] was found and synthesized using a solution growth method. The diffraction pattern, morphology, element composition and structure of the crystal were analyzed by XRD, SEM and CCD. The results implied that K3[InCl6] is monoclinic, is of the space group P21/c, has a chemical formula of K3[InCl6], a Z = 4 and with the following cell parameters: a = 12.188 Å, b = 7.553 Å, c = 12.703 Å, ? = 90.00°, ? = 108.96°, ? = 90.00°, V = 1105.98 Å3.
  • LI Yingpin, ZHOU Xiaoquan, ZHOU Huijing, SHEN Zhurui, CHEN Tiehong
    Manganese dioxides with various morphologies were prepared using a common hydrothermal method without any templates or additives. The evolution of the morphology was accompanied by the gradual conversion of the polymorphic forms from ?-type to ?-type. Meanwhile, MnO2 microspheres, urchin-like nanostructures and nanowires were successfully synthesized. The products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The evolution process can be explained by the Ostwald Ripening mechanism.
  • CAI Chuanlun, SHI Qiang, LI Lili, YIN Ligang, TANG Gongben, YIN Jinghua
    Polypropylene grafting with AA was prepared by reactive extrusion with pre-irradiated PP (rPP) as the homogeneous initiator. The effects of the pre-irradiated dose, the fraction of rPP and the concentration of acrylic acid on the grafting reaction were studied and the grafted PP was characterized by Fourier transition infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and polarized light microscopy (PLM). The results show that the degradation of PP was suppressed efficiently with this novel method for preparing PP-g-AA copolymers, and the grafted copolymers with good mechanical properties were obtained. It was found that the product with higher graft degree (Gd)(0.19%) and relatively excellent mechanical properties can be produced if the mass ratio of PP/rPP/AA is 90:10:0.8, where the selected pre-irradiation dose of rPP is 4 kGy. Moreover, an adhesive strength of 4.88 kN/m was reached in the PP-g-AA/aluminum laminate.
  • XU Guangjun, GU Wen, MA Xiaofang, FENG Li, YAN Shiping, LIAO Daizheng, CHENG Peng, XU Guangjun, FENG Li
    The interaction between CT-DNA and a ternary copper (II) complex, [Cu(phendio)(L-Phe)(H2O)](ClO4)·H2O (CuPP, phendio = 1,10-phenanthroline-5,6-dione, L-Phe = L-phenylalanine), has been conducted by electronic spectra, fluorescence spectroscopy and cyclic voltammetry. It has been found that the max. absorption peak from the electronic spectra is red shifted and the intensity is weakened and that the values of peak current from cyclic voltammetry are decreased significantly in the presence of DNA compared with that in the absence of DNA. At the same time, the complex can quench the emission intensity of EB-DNA system. The existence of the intercalation mode between the complex and DNA was proven. By submarine gel electrophoresis, we found that the copper(II) complex can cleave circular plasmid pBR322 DNA into nicked and linear forms in the presence of ascorbic acid and H2O2.
  • LI Xiaoliu, ZHANG Pingzhu, TIAN Jun, DUAN Kefang, CHEN Hua
    A practical and efficient synthesis of 1,4-dideoxy-1,4-imino-D-arabinol and its partially protected derivatives has been described via the key intermediate with a norbornane-like structure using D-glucose as a starting material.
  • ZHONG Qiling, ZHANG Bing, RAO Guishi, DING Yuemin, WANG Guofu, JIANG Yuxiong, REN Bing, TIAN Zhongqun
    The morphology and structure of Pt-CNTs/GC electrodes were characterized via Transmission Electron Microscopy (TEM) and selected area electron diffraction. The electro-oxidation behavior of CO and methanol on Pt-CNTs/GC electrodes were studied with cyclic voltommograms or chronoamperometry. Three oxidation peaks were observed for CO absorbed on Pt-CNTs/GC electrodes. Methanol was found to be dissociated spontaneously on the electrode to produce a strong absorbed intermediate CO. Among the three oxidation peaks, peak I was presumed to be due to the bridged CO absorption while peaks II and III were attributed to the split in the linear CO which is absorbed on the Pt-CNTs/GC nanocluster with different particle size and Pt film. The oxidation current of methanol on the Pt-CNTs/GC electrode did not always increase with the increase in the amount of Pt loading. The result indicates that there is an optimal Pt loading for methanol oxidation. It is necessary to select the catalyst with proper Pt loading when the anode of a direct-methanol fuel cell is prepared.
  • REN Huixue, YANG Yanzhao, LIN Jimao, QI Yinshan, ZHANG Yeqing
    A new synthetic method for 5-bromo-3-sec-butyl-6-methyluracil (Bromacil) using 2-bromobutane and urea as starting materials is described. The synthesis involved condensation, cyclization and bromination with a total yield of 60%. The structure of Bromacil was determined by 1H NMR, 13 C NMR and IR spectroscopy.
  • GONG Jie, LIU Yang, ZONG Zhanguo, WANG Lili, YANG Jinghai
    Hexagonal close-packed Ni nanoparticles were synthesized using a heat-treating technique with the precursors prepared by the sol-gel method. The synthesis condition, structure, and morphology of the samples were characterized and analysed by thermogravimetric analysis (TG), differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results indicate that the hexagonal close packed Ni nanoparticles were synthesized at a heat-treating temperature of 300°C. The cell constants are calculated at a = 0.2652 nm and c = 0.4334 nm. The average grain size of the hexagonal close-packed Ni particles evaluated by Scherrer equation is about 12 nm. The phase transformation from a hexagonal close-packed Ni to a face-centered cubic Ni structure occurred when the heat-treating temperature was increased.
  • WANG Songrui, LIN Wei, ZHU Yuexiang, XIE Youchang, CHEN Jingguang G
    Pd/Ni bimetallic catalysts were prepared by replacement reactions, characterized by X-ray diffraction, CO chemisorption and H2 temperature-programmed desorption, and evaluated for hydrogenation of cyclohexene, styrene and acetone. The results show that Pd atoms are monolayer-dispersed on the Ni surface in these Pd/Ni catalysts. Consequently, Pd/Ni catalysts are much more active than Pd/Ni and Pd/?-Al2O3 with the same Pd loading prepared by the conventional impregnation method.
  • XU Xiaojun, LIU Xiangyi, YANG Yuming
    The hydrophobic formation cationic starch (PSOAMDA) was prepared from starch (St), octadecyl acrylate (OA), acrylamide (AM) and dimethyl diallyl ammonium chloride (DMDAAC) by means of inverse suspension polymerization with redox initiator. Water with algae from Dianchi Lake was tested with PSOAMDA. Results show that when the molar ratio of St: AM: DMDAAC: OA is 4:8:1.5:0.6 and the reaction temperature is 40°C with a reaction time of 3 h, the monomer conversion yield, graft percentage and cationic degree is 92.4%, 63.8% and 7.3%, respectively, and M? = 3.26 × 106 g/vmol. It had been found from the flocculation of disposed water with algae from Dianchi Lake that the transparency and COD elimination reach to 93.5% and 70.3%, respectively, with 15 mg/L PSOAMDA and at pH 6, vs. 91.3% and 69.2% obtained with the commercial cationic polyacrylamide (PAM-C). When PSOAMDA dosage is 10–25 mg/L and the pH of aqueous solution is 6–10, the flocculation performance is well capable of dealing with the water with algae from Dianchi Lake.
  • LIN Zhidan, ZHANG Xiuju, ZENG Rong
    The polyvinyl acetal sponge modified by chitosan was prepared by adding chitosan/polyvinyl alcohol (PVA) solution during the acetalation reaction of PVA and formaldehyde. The effect of vesicant and chitosan to the pore morphology, water absorption ratio, water absorption rate, expansion time and mechanical properties were studied. The polyvinyl acetal sponge modified by chitosan was used as a hemostatic packing material for the injured rabbit nasal tissue. The hemostatic effect and the healing effect of the modified sponge on the nasal mucosa after nasal surgery were studied. The results indicated that the polyvinyl acetal sponge modified by chitosan has an interconnected pore structure and the wall between large pores also has small pores. The chitosan adhered on the inner surface of the pores. The increased content of vesicant led to an increase in pore diameter, in the water absorption ratio and in expansion time. However, there was only a small change in the water absorption rate and a decrease in tensile strength and compression strength were noted. With an increase in chitosan content, the pore diameter and interconnection of the sponge was reduced. Water absorption ratio, expansion time and water absorption rate decreased, but tensile strength and compression strength improved. Observation of the rabbit nasal tissue after surgical operation suggested that polyvinyl acetal sponge modified by chitosan has an anti-inflammatory, hemostatic and anti-adherent characteristic and could promote the healing and functional recovery of rabbit nasal mucosa.
  • REN Xiuhua, DU Guang, ZONG Kai, MA Baoxia, ZHOU Bingfeng
    To study the bioactive constituents from Andrographis paniculata, two compounds were isolated and purified by column chromatography on AB-8 macroporous adsorption resin and polyamide. Their structures were determined by various spectroscopic methods, including UV, FABMS, 1H-NMR, 13C-NMR, DQFCOSY, TOCSY, HMQC, HMBC, and NOESY. The 1H-NMR and 13C-NMR signals of the two compounds were assigned. The structures of the two compounds were elucidated as 5,4′-dihydroxy-7-methoxyflavone-6-yl-?-D-glucopyranoside and 5,4′-dihydroxy-7-methoxyflavone- 8-yl-?-D-glucopyranoside, respectively.
  • SONG Xiaolan, HE Xi, YANG Haiping, XU Dayu, JIANG Nan, QIU Guanzhou
    The thermal decomposition of CeO2 nanocrystalline precursor prepared by chemical precipitation method was investigated using thermo-gravimetric/differential scanning calorimetry (TG/DSC) and X-ray powder diffraction (XRD). In particular, the differential thermal analysis curves for the decomposition of CeO2 nanocrystalline precursor were measured at different heating rates in air by a thermal analyzer (NETZSCH STA 449C, Germany). The kinetic parameters of the thermal decomposition of CeO2 nanocrystalline precursor were calculated using the Kissinger method and the Coats-Redfern method. Results show that the apparent active energy E of the reaction is 105.51 kJ/mol, the frequency factor lnA is 3.602 and the reaction order n is 2. This thermal decomposition process can be described by the anti-Jander equation and a three-dimensional diffusion mechanism.
  • WANG Kangcheng, HUANG Wei, ZHOU Yongfeng, YAN Deyue
    A small molecule (GMS-SA2) with one alkyl chain and two terminal carboxyl groups was synthesized successfully by the reaction of glyceryl monostearate (GMS) with excess succinic anhydride (SA). Then, GMS-SA2 was used as a coupling agent to condensate with polyethylene glycols (PEG) of different molecular weight or polyethylene glycol monomethyl ether (PEGm) in the presence of stannous octoate as catalyst and diphenyl ether as azeotropic agent. The AB2 star-shaped miktoarm copolymers were obtained successfully and were characterized by 1H-NMR, DSC, GPC, XRD, FTIR and polarizing microscopy. The results of DSC and XRD measurements indicate that the crystallization temperature and the melting temperature of the AB2 star-shaped miktoarm copolymers are different from those of the corresponding linear PEGs, because the existing of GMS-SA2 alters their crystalline growth velocity and the perfect degree of crystals. It is very important to control the crystal morphology of star-shaped copolymers by introducing the miktoarm into the star-shaped polymers and adjusting its content in star-shaped polymers.
  • FANG Haihong, HU Binyuan, WANG Lingshen, LU Rongli, YANG Cui
    Nanometer MgO was prepared via a sol-gel auto-combustion technique using magnesium nitrate as raw material and citric acid as chelating agent. IR spectra of the dried gel were used to investigate the structure of the precursors. By studying the different TG curves of magnesium citrate gel prepared by different methods, we found that a combustion process occurred and the nitrate ions acted as an oxidant in the combustion process. TEM photographs of synthesized powders from the sol-gel auto-combustion showed that the crystallites were uniform in size. In addition, the XRD pattern of this sample showed that the particle size was 8.9 nm. The BET curves, in turn, showed that the specific surface of the sample was 26.34 m2/g. The mechanism of the frothing process in restraining agglomeration is discussed.
  • LI Fang, XU Kejing, DONG Cheng, CHEN Juan
    A nano-alumina with high specific area was prepared using a homogeneous precipitation method with titanium dioxide and barium oxide as modifying additives. Results showed that 5 wt% TiO2 or BaO added in the alumina gels can decrease the particle size and increase the specific area, but excessive TiO2 or BaO could deteriorate the properties of ?-Al2O3.
  • SHI Yali, ZHANG Ping, CAI Yaqi, MOU Shifen
    An improved ion chromatographic (IC) method was developed to determine trace levels of perchlorate in environmental water samples. Perchlorate was separated in the hydroxide selective column IonPac AS16 using NaOH as an eluent with an organic modifier. To eliminate the coelution of perchlorate and 4-chlorobenzene sulfonate (4-CBS), an organic solvent as modifier was added to the eluent. Of four organic solvents studied, acetonitrile proved to be the most efficient based on the retention time of perchlorate and 4-CBS. To improve the method sensitivity, a concentrator column (AG19) was used to concentrate perchlorate online. With the adoption of a preconcentration step, the sensitivity of our method was improved and the method detection limit (MDL) was reduced to 0.1 ?g/L. The linear range was from 0.2 ?g/L to 200 µg/L with a linear correlation coefficient of 0.9989 and the relative standard deviation (RSD) of peak area for eleven successive injections of 0.5 ?g/L perchlorate was 4.2%. The method had been applied to the determination of perchlorate in some real environmental water samples and recovery was between 93% and 113%.
  • FANG Jinian, DING Kan, DONG Qun, SHI Lei, CHEN Kaoshan
    A water-soluble polysaccharide (CPS-0) was obtained from the root of Cudrania tricuspidata (Carr.) Bur., by hot water extraction (70°C), deproteination using enzymolysis and Sevag method, precipitation with ethanol, and fractionation through DEAE-Sephadex A-50 chromatography. The purity of CPS-0 was determined by HPLC and the structure was elucidated by monosaccharide composition analysis, methylation analysis, GC, GC-MS, NMR spectral (1H-NMR, 13C-NMR, HMQC), UV, IR, and elemental analysis. The CPS-0 was found to contain glucose residues only. The average repeating unit is a decasaccharide having a backbone consisting of 1,4-linked ?-D-glucopyranosyl residues to which the side chain consisting of terminal and 1,4-linked ?-D-glucopyranosyl residues was attached at position 6 of the branching residues.
  • Xu Hongyan, WU Huaqiang, XU Dongmei, WANG Qianyi
    Nanocrystalline nickel with an average diameter of about 16 nm and a face-centered cubic (fcc) structure was uniformly attached to the surface of carbon nanotubes (CNT) by wet chemistry. The sample was characterized by X-ray powder diffraction and transmission electron microscopy (TEM). A glass carbon electrode modified with nickel-modified multi-wall carbon nanotubes (MWCNTs-Ni/GCE) was prepared. The electrochemical behavior of the MWCNTs-Ni/GCE and the electrocatalytic oxidation of methanol at the MWCNTs-Ni/GCE were investigated by cyclic voltammetry in 1.0 mol/L NaOH solution. The cyclic voltammograms showed that the electron transfer between ?-Ni(OH)2 and ?-NiOOH is mainly a diffusion-controlled quasi-reversible process, and that the electrode has high catalytic activity for the electrooxidation of methanol in alkaline medium, revealing its potential application in alkaline rechargeable batteries and fuel cells.
  • YAN Xuejia, DENG Yonghong, WANG Xiaogong
    The effect of pH value on the electrostatic layer-by-layer self-assembly and the photo-responsive behavior of Poly{2-[4-(4-ethoxyphenylazo)phenoxy]ethyl acrylate-co-acrylic acid} (PEAPE) was studied. Results show that in the studied pH value range, the lower the pH value is, the higher is the UV-vis absorbance and the larger is the thickness of the multilayer films. FTIR studies indicate that the azo polyelectrolyte exhibits a different ionization degree in solutions with different pH values. The higher absorbance and the larger thickness of the layer-by-layer films can be attributed to the low ionization degree and the shrinkage conformation of PEAPE in the solution with low pH values. FTIR analysis also confirms that the driving force for layer-by-layer self-assembly of PEAPE and PDAC is the electrostatic interaction.
  • HAN Qingjuan, WU Hailong, NIE Jinfang, XIA Alin, ZHU Shaohua, YU Ruqin
    The concentration of reserpine in urine was directly and quantitatively measured by using the excitation-emission fluorescence (EEM) combined with three-way calibration methodologies. Two calibration methods are based on the alternating trilinear decomposition (ATLD) and the self-weighted alternating trilinear decomposition (SWATLD) algorithms, respectively. These chemometric methodologies have the second-order advantage, which is the ability to get accurate concentration estimates of interested analyte(s) even in the presence of uncalibrated interferences. The satisfactory results on spiked urine samples are obtained, when the component number was chosen to 3 (N = 3) for both the methods. This experiment is easily carried out without time-consuming and complicated pretreatment. It has proved that the three-way calibration methodologies based on ATLD and SWATLD can be feasible to directly quantify the medical content of reserpine in urine.
  • ZHANG Yinmin, LAN Ding, WANG Yuren, WANG Fengping
    The ZnO films with two-dimensional ordered macroporous structure were successfully fabricated through hydrothermal crystal growth of ZnO on the ZnO substrate covered with a monolayer of polystyrene (PS) spheres as template. The precursor solution of hydrothermal crystal growth of ZnO were prepared by equi-molar solution of Zn(NO3)2·6H2O and hexamethylenetramine (HMT). The confinement effect of the PS spheres template on the growth of ZnO nanorods and the influence of sodium citrate on the crystal growth of ZnO had been studied. The film surface morphology and the preferential growth of ZnO crystal were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Also, the photoluminescence spectrum of ZnO films had been measured, and the corresponding mechanism was discussed.
  • SITU Yue, HU Jianfeng, HUANG Hong, FU Heqing, ZENG Hanwei, CHEN Huanqin
    A novel epoxidized soybean oil (ESO) internally toughened phenolic resin(ESO-IT-PR) with both good toughness and excellent thermal stability was prepared as the matrix resin of copper clad laminate (CCL). FTIR was adopted to investigate the molecular structure of modified phenolic resins and SEM was used to observe the micro morphology of their impacted intersections. The properties of CCLs prepared with these modified phenolic resins were studied to determine the optimal process and investigate the toughening mechanism. The main modifying mechanism is the etherification reaction between phenol hydroxyl and ESO catalyzed by triethanolamine and the chain extension polymerization between ESO and multi-amine gives the long-chain ESO epoxy grafting on the phenolic resin prepolymer. when the ESO content is 30% and the curing agent content is 7%, the ESO toughened phenolic resin possesses optimal performance. The flexible ESO epoxy shows significant toughening effect and it crosslinks with the phenolic resin to form an internally toughened network, which is the key factor for improving the solderleaching resistance of CCL prepared with this modified phenolic resin.