Sep 2008, Volume 3 Issue 3

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  • Kumar Rakesh, Choudhary Veena, Varma Ik, Mishra Saroj
    Banana fiber, a waste product of banana cultivation, has been used to prepare banana fiber reinforced soy protein composites. Alkali modified banana fibers were characterized in terms of density, denier and crystallinity index. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were also performed on the fibers. Soy protein composites were prepared by incorporating different volume fractions of alkali-treated and untreated fibers into soy protein isolate (SPI) with different amounts of glycerol (25%–50%) as plasticizer. Composites thus prepared were characterized in terms of mechanical properties, SEM and water resistance. The results indicate that at 0.3 volume fraction, tensile strength and modulus of alkali treated fiber reinforced soy protein composites increased to 82% and 963%, respectively, compared to soy protein film without fibers. Water resistance of the composites increased significantly with the addition of glutaraldehyde which acts as crosslinking agent. Biodegradability of the composites has also been tested in the contaminated environment and the composites were found to be 100% biodegradable.
  • LIU Taiqi, YANG Liyan, YU Jianxiang
    2-Methylthiophene (1) was treated at 0°C with liquid bromine to form 3,5-dibromo-2-methylthiophene (2) which reacted with tributyl borate to give 2-methyl-3-bromo-5-boronate thiophene (3) at -78°C. Treatment of 3 with 3,4-difluorobrombenzene gave 2-methyl-3-bromo-5-(3,4-difluorophenyl)thiophene (4). Finally, a novel photochromic dithienylethene compound, 1,2-bis[2-methyl-5(3,4-difluorophenyl)-3-thienyl]perfluorocyclopentene (DT-1), was synthesized by the reaction of 4 with perfluorocyclopentene at -78°C. The compound (DT-1) was characterized by IR, NMR, MS, elemental analysis and its photochromic behavior was also discussed.
  • YANG Manman, XI Xiaoli, YANG Pin
    The action of the three kinds of new third generation cephalosporin-class drugs, cefepime hydrochroride, cefpiramide and ceftizoxime with HSA and BSA was studied at different temperatures through the fluorescence method. First, the binding constants were calculated by using fluorescence quenching and enhancement theoretical equations. Their thermodynamic functions were also calculated. Because the KA corresponding to the different theoretical equations are not completely the same, the thermodynamic parameters calculated are also different. In this paper, the differences among these thermodynamic data obtained from the different theoretical equations were analyzed and the results show that the thermodynamic data deduced from fluorescence enhancement are more reasonable. Thus, we propose that even when the fluorescence quenching action of the acceptor-substrate is studied, more realistic data can be obtained by using the fluorescence enhancement equation.
  • ZHANG Yuehua, ZENG Heping, CHEN Dongfeng
    The ointment of plastrum testudinis was extracted using petroleum ether, ether and dichloromethane sequentially and the extracts were methyl-esterified. The effects on the proliferation of bone marrow mesenchymal stem cells (bMMSCs) were examined by MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay and flow cytometry analysis. The volatile components of the samples were studied by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The results show that the methyl-esterified parts can promote the proliferation of stem cells and they all contain palmitic acid methyl ester. Palmitic acid methyl ester can promote proliferation when the concentration was 0.15 ?g/?L. It may be concluded that the palmitic acid methyl ester is important for the methyl-esterified parts that have effects on proliferation.
  • XUE Jinping, LIU Hong, CHEN Naisheng, HUANG Jinling, FAN Changan, HONG Huming
    Four amphipathic cobalt(II), nickel(II), copper(II), and zinc(II) coordination compounds of tetrakis-?-(2-methyl-8-quinolinoxy)phthalocyanine are synthesized using “DBU catalytic method”. The titled complexes are characterized by elemental analysis, mass spectra, UV-Vis, and IR spectra. In addition, the rates of photogenerated singlet oxygen and the rate constants of photodynamic oxidation of amino-acid substrate by the complexes are measured under the optical excitation at 670 nm, and the relations between their structures and their photosensitivities are discussed.
  • LIU Yi, QIAN Yitai
    A single phase of monoclinic MnV2O6 nanoflakes was prepared by a hydrothermal process at 180°C for 18 h, using Mn (CH3COO)2·4H2O and NH4VO3 as starting materials and using acetic acid to adjust the pH value of the reaction solution. The as-prepared samples were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray photoelectron spectrum (XPS) measurements further confirm the component of MnV2O6. Results indicated that the products consisted of a large quantity of compact accumulated nanoflakes, with average width of 0.85 ?m, thickness of 100 nm and lengths up to 1.7 ?m.
  • YANG Hua, TIAN Rui, LI Ye
    The organic reactions catalyzed by 1, 4-diazabicyclo [2.2.2] octane (DABCO) are reviewed. Most of the reactions start conveniently from available substrate and proceed under mild conditions. The reactions are environmentally friendly and the catalyst can be recycled in some cases. The perspectives on DABCO-catalyzed reactions are pointed out.
  • TSANG Po keung, FANG Zhanqiang, LIU Hui, CHEN Xiaolei
    The kinetics of the adsorption of an endocrine disruptor, di-n-butyl phthalate (DBP), by four different granulated-activated carbons (GACs) is presented in this paper. Results showed that adsorption of DBP by the four GACs followed first-order kinetics and the adsorption constant of the four GAC was found to follow the order: nut shell > coconut shell > Coaly carbon 1.0 > Coaly carbon 1.5. Batch adsorption studies were also conducted to investigate the effect of pH on the adsorption process. The optimum pH for the removal of DBP from aqueous solutions under the experimental conditions used in this work was found to be 5.0. The characterization of the carbon surfaces was conducted by using scanning electron microscopy (SEM). Furthermore, results from infrared spectroscopic (IR) studies showed that physical adsorption plays an important role in the adsorption of DBP by the four selected GACs.
  • YANG Chun, XU Gongfeng, WANG Qinglun, LIAO Daizheng, LIU Bin
    The bimetallic complex of Ni2Co(TTHA)12H2O (TTHA = triethylene tetraminehexaacetic acid) was synthesized and characterized structurally and magnetically. The title complex crystallizes in the triclinic space group P + with a = 0.7316(2), b = 0.8624(2), c = 1.5041(4) nm; ? = 73.38(2), ? = 83.97(2), ? = 70.50(2)°. The crystal structure is built up of [Ni2(TTHA)(H2O)2]2-, Co(H2O)62+ and water molecules. The variable magnetic measurement shows that there is strong antiferromagnetic interaction between two Ni(II) ions in [Ni2(TTHA)(H2O)2]2- with JNi-Ni = -141.64 cm-1, gNi = 2.21 and that the constant of spin-orbit coupling of Co(II) ion is -134.8 cm-1.
  • ZHOU Yongfeng, YAN Deyue, HUANG Wei, WANG Kangcheng
    A small molecule core (TMP-SK3) with three terminal carboxyl groups was synthesized successfully by the reaction of 1,1,1-trihydroxymethylpropane with the excessive sebacic acid diacetic anhydride (SK). Then, the core molecule was used as a coupling agent to condensate with polyethylene glycols (PEG) of different molecular weights or polyethylene glycol monomethyl ether (PEGm) in the presence of stannous octoate as catalyst and diphenyl ether as an azeotropic agent to remove water. Thus, the three-arm star-shaped PEGs was obtained successfully and characterized by 1H-NMR, DSC, GPC and XRD etc.. DSC measurements indicate that the crystallizing and the melting temperatures of the three-arm star-shaped PEGs were different from those of the corresponding linear PEG because the existence of TMP-SK3 altered its crystallizing velocity and perfect degree of crystallization.
  • REN Yuanlin, CHENG Bowen, ZHANG Jinshu, ZANG Hongjun, KANG Weimin, DING Changkun
    The title compound N,N′-di(diethoxythiophosphoryl)-1,4-phenyl- enediamine was synthesized by the reaction of diethoxythiophosphoryl chloride with p-phenylenediamine and characterized by elemental analysis, IR, and 1H NMR spectra. Its crystal structure was determined by X-ray diffraction analysis and the thermal property was studied by TG analysis. The relative molecular weight of the title compound is 412.42. The crystal structure belongs to the orthorhombic, Pbca space group, with a = 0.86936(16) nm, b = 1.2787(2) nm, c = 1.8897(3) nm, ? = 90°, V = 2.1006(7) nm3, Z = 8, Dc = 1.304 g/cm3, ?(Mo K?) = 0.425 mm-1, F(000) = 872, S = 1.052, the final R = 0.0628 and wR = 0.1860 for 1852 observed reflections with I > 2?(I). The X-ray diffraction analysis demonstrates that the crystal structure is centrosymmetric. The weak N–H...S intramolecular hydrogen bonds were observed to link the molecules into sheets. The TG analysis shows that the title compound has good thermal stability and char forming capability and its fire retardation for polyacrylonitrile reveals that the compound is an excellent intumescent fire retardant.
  • WANG Chenjing, YU Jiang, XING Jianmin, LIU Huizhou
    With the aim of improving the microstructures and properties of TiO2 pillared montmorillonite (MMT), a long-chain polymer (polyoxypropylenediamine, PPO-D 2000) was used as a template to synthesize composite pillared MMT. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometer, Fourier Raman (FT-Raman) spectrophotometer, thermo-gravimeter/differential thermo-gravimeter (TG/DSC), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) methods. The results show that as compared to low-molecular weight surfactant, this polymer significantly expanded the interlayer spacing and thus more TiO2 could be intercalated into MMT. The specific surface area of polymer/TiO2 pillared MMT was increased by 13% with comparison to TiO2 pillared MMT and rose to 241.52 m2/g. Both the pore diameter and volume are doubled, and thus the pore structure is optimized markedly. The investigation on the photo-catalytic degradation of methyl orange in aqueous solution show that the modulation of polymer molecules raise the adsorption content of montmorillonite and improve the photo-catalytic activity. Therefore, this process provides a novel alternative to design and prepare the advanced eco-catalytic materials with high adsorption capacity and photo-catalytic activity.
  • PAN Chunyue, LONG Qingde, YU Dian, RAO Yanping, WU Nianqian, LI Xingcui
    A series of N-isopropylacrylamide (NIPAAm) copolymer gels with different hydrophilicities were prepared from NIPAAm, hydrophilic acrylamide (AAm) and hydrophobic butyl methacrylate (BMA). The swelling and thermo-responsive properties of PNIPAAm P(NIPAm-co-BMA) and P(NIPAm-co-AAm) copolymer hydrogels were investigated. The drug loading and releasing behaviors for two kinds of model drug with different hydrophilicities were studied. The result shows that the copolymer gels present negative thermo-sensitivities. The lower critical solution temperature (LCST), equilibrium swelling degree and the initial swelling rate increase as the hydrophilicity of gels increases when the temperature is below the LCST. With increasing gel hydrophilicity the loading ratio for sodium salicylate increases, while for salicylic acid, the reverse is observed. The initial drug releasing rate of sodium salicylate and salicylic acid also increase with increasing gel hydrophilicity. The initial drug releasing rate of sodium salicylate is significantly higher than that of salicylic acid. For salicylic acid which is less hydrophilic, the equilibrium releasing ratio at high temperature is lower than that at low temperature while for sodium salicylate which is more hydrophilic, the equilibrium releasing ratio at high temperature is almost the same as that at low temperature. Equilibrium releasing ratios of the three gels are significantly different from each other for salicylic acid when the temperature is below LCST while the equilibrium releasing ratios of the three gels are all 100% for sodium salicylate.
  • ZHANG Yuqing, ZHANG Yahui, QIN Zhen, MA Zhenrong
    One kind of built-in silica adsorbent, which has high adsorption selectivity to rutin, was synthesized using molecular imprinting technology by the following steps: synthesis of precursor from the reaction between water soluble rutin (as template molecule) and the functional monomer chloropropyltriethoxysilane, co-hydrolysis of the precursor and tetraethoxysilane (TEOS), sol-gel aging process, and removal of template molecules. The results of adsorption experiment show that this adsorbent has a high adsorption capacity for rutin, and good adsorption selectivity towards rutin even under the interference of a flavone with a similar structure. TEM photos suggest that nanocaves corresponding to rutin were formed inside the adsorbent while FTIR spectra indicate that new bond was generated during the recognition process.
  • HE Rong, YOU Xiaogang, TIAN Hongye, GAO Feng, CUI Daxiang
    The comparison of growth processes and fluorescent properties of CdTe semiconductor quantum dots (QDs) that are synthesized in water with different modifiers are discussed in this paper. The samples are characterized through ultraviolet-visible spectra (UV-Vis), photoluminescence spectra (PL) and zeta potential. The results show that when the reaction time is prolonged for the same modifier, the ultraviolet absorption peak and fluorescent emission peak present obvious red shifts and the diameters of the QDs continuously increase. With the same reaction time but different modifiers, QDs with different diameters can be gained. The average full width at half maximum of the photoluminescence spectra is about 50 nm which shows that the monodispersity is quite good. Under the best reaction conditions, the highest quantum yield (QY) can be attained by using thioglycollic acid (TGA) as modifier when the reaction time is 240 min. The zeta potential is influenced by the modifier and pH.
  • GOU Pengfei, ZHU Weipu, SHEN Zhiquan
    Two calixarene derivatives (2a, 2b) have been synthesized and used as macro-initiators to prepare star-shaped poly(?-caprolactone)s (SPCLs) via controlled ring-opening polymerization of ?-caprolactone in the presence of yttrium tris(2,6-di-tert-butyl-4-methylphenolate) [Y(DBMP)3]. The molecular weight of SPCLs was characterized by end group 1H-NMR analyses and size-exclusion chromatography (SEC). The results indicate that SPCLs based on a calix[4]arene derivative (2a) are well-defined four-arm star polymers with reasonably narrow molecular weight distributions in the given molecular weight range, while SPCLs based on a calix[6]arene derivative (2b) are star polymers with not so defined structures. Differential scanning calorimetry (DSC) analyses suggest that the maximal melting point, the crystallization temperature and the degree of crystallinity of SPCLs increases with the increasing molecular weight and are lower than those of the liner poly(?-caprolactone) (LPCL) counterpart. Furthermore, polarized optical microscopy (POM) indicates that SPCL exhibits irregular spherulites with poor morphology and slower crystallization rate, whereas LPCL shows fast crystallization rate and good spherulitic morphology.
  • LI Li, LIU Zhanpeng, LIN Yuanbin
    A new convenient synthesis of a series of 1-aryl-2-propanones using aromatic amines as precursors, via diazo-reaction and improved Meerwein arylation reaction under mild conditions, was achieved. In addition, 1-[3,5-bis(trifluoromethyl)phenyl]-2-propanone is a new compound among the synthesized compounds. This approach is an efficient synthetic method for the aryl-propanones with different substituting groups.
  • CHEN Zhengnian, XIE Hongfeng, YANG Hu, WANG Zhiliu, CHENG Rongshi
    The analyses of the composition of a binary mixture composed of two kinds of industrial complicated materials have great importance for formulation in practice. The present paper provides a quantitative size exclusion chromatography (SEC) method based on the principle of absolute quantification of SEC to solve the problem. The conventional data treatment procedure for the differential refractive index (DRI) signal of SEC H(V) is improved first by dividing it with the injected sample weight and leads to a novel defined weight normalized distribution Hw(V) and its integral Iw(V). These two distributions reflect the response constant of the sample in addition to the conventional normalized distribution F(V). The difference of the average response constants of the composing components provides a sensitive method to compute the composition of their mixture from its Hw(V) or Iw(V). The method was applied to mixtures of a kind of industrial asphalt and paraffin diluents as an example, and successful results are obtained.
  • WANG Runhe, BU Jianhua, LIU Junmin, HANG Yiping, LIAO Shijun
    A novel calix[4]arene-based fluorescent chemosensor bearing a 2-aminopyridine moiety and a naphthalenic fluorophore was synthesized The chemical structure of the product was elucidated by FT-IR, MS-FAB, NMR and elemental analyses. Then, the properties and identification mechanism of the synthesized chemosensor were investigated. The results show that the chemosensor exhibits selective fluorescent quenching in the presence of aromatic organic acid in acetonitrile solution, and that the binding ability of the chemosensor with organic acid is in the order of p-cyanic-benzyl acid > p-chloric-benzyl acid > p-methoxyl-benzyl acid > benzyl acid.
  • YANG Chunhai, ZHANG Shenghui, LIU Yingxuan, HUANG Wensheng
    A multi-wall carbon nanotubes (MWNTs)-Nafion film-coated glassy carbon electrode (GCE) was fabricated and the electrochemical behavior of ofloxacin on the MWNTs-Nafion film-coated GCE were investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current of ofloxacin increased significantly on the MWNTs-Nafion film modified GCE compared with that using a bare GCE. This nano-structured film electrode exhibited excellent enhancement effects on the electrochemical oxidation of ofloxacin. A well-defined oxidation peak attributed to ofloxacin was observed at 0.97 V and was applied to the determination of ofloxacin. The oxidation peak current was proportional to ofloxacin concentration in the ranges 1.0 × 10-8 to 1.0 × 10-6 mol/L and 1.0 × 10-6 to 2.0 × 10-5 mol/L. A detection limit of 8.0 × 10-9 mol/L was obtained for 400 s accumulation at open circuit (S/N = 3). This method for the detection of ofloxacin in human urine was satisfactory.