Dec 2007, Volume 1 Issue 4

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  • LIU Yaochi, XU Wei, XU Weijian, LIU Hanmao, ZHANG Xiaowen
    In recent years, resins prepared via molecular imprinting technology have received considerable attention owing to their recognition and selective adsorption. This paper deals with the comparative investigation between a uranyl sulphate imprinted ion-exchange based on self-assembling molecular imprinting technology and two kinds of commercial uranium resins (the medium pore resin D263 and strong base resin 201×7). The studies were focused on their kinetics performance, adaptability toward pH, and performance of saturation and elution in laboratory-scale column. The results show that the imprinted ion exchange resin has the fast kinetics, high adaptability toward pH, and good adsorption and elution performance.
  • WEI Shanshan, LIU Yuejun, LI Xianggang, HUANG Yugang, WANG Xiayu, ZHANG Ping
    The polyamide 6 (PA6)/SiO2 nanocomposites were prepared by in situ polymerization and the rheological behaviors were investigated. The morphology of resultant materials was characterized by scanning electron microscopy (SEM) and the rheological behaviors were characterized by capillary rheometer. The results showed that the SiO2 particle size was around 50 nm and the particles dispersed evenly in PA6 matrix. The nanocomposites were pesudoplastic fluids and the apparent viscosities of nanocomposites increased initially and then decreased with the increase in nano-SiO2 content at the same temperature. The non-Newtonian indexes of nanocomposites were smaller than those of pure PA6. With the increase in nano-SiO2 content the apparent viscous activation energies of nanocomposites increased initially and then decreased. The rheological behaviors revealed that there were strong interactions between PA6 macromolecule chains and nano-SiO2 particles.
  • PENG Xuhui, LE Yuan, BIAN Shuguang, LI Woyuan, WU Wei, DAI Haitao, CHEN Jianfeng
    To prepare stable electrophoretic ink (E Ink) needs color particles to be uniformly dispersed in the organic medium. Thus, t-he modification of inorganic particle surface is required. In this paper, Titanium dioxide modified by alumina has been studied. The surface composition and structures of modified particles have been characterized by X-ray photoelectron spectrometer (XPS), X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FT-IR). The dispersibility and electrophoretic mobility of these particles in tetrachloroethylene (TCE) have been investigated by laser particle size analyzer, static sedimentation and electrophoretic instrument. Effects of temperature, pH value and stirring rate on the dispersibility and the charge property of samples have been discussed. The results indicate the settle time of modified TiO2 can last 120 h with the response time of 35 s under the optimized modifying conditions, in which temperature is 85°C–90°C, pH is 8–9 and stirring rate is 800 r · min-1. The dispersibility and electrophoretic mobility have been significantly improved, which means that the modified TiO2 is suitable for electrophoretic ink particles.
  • YE Lin, ZHAO Yumei, FENG Zengguo, BAI Ying, WU Feng
    An oxetane-derived monomer, 3-acryloyloxymethyl-3′-methyloxetane (AMO) was prepared from the reaction of 3-hydromethyl-3-methyloxetane with acryloyl chloride. The cationic ring-opening copolymerization of AMO with another oxetane-derived monomer, 3-(2-(2-(2-methoxyethylenoxy)ethylenoxy)ethylenoxy)-3′-methyloxetane (MEMO) was conducted in CH2Cl2 solution using BF3 ·OEt2/1, 4-butanediol as a co-initiator. The resulting copolymers were characterized by FTIR, 1H NMR and Gel Permeation Chromatography (GPC) analyses, and it was found that the enchained ratio of AMO in the copolymers is far lower than its feed ratio. They were crosslinked in situ via the radical polymerization of the vinyl group initiated by BPO after doping with lithium trifluoromethanesulfonimide (LiTFSI) to give rise to tough polymeric electrolyte films. The ionic conductivity was measured at varying content of AMO and different concentration of lithium salt LiTFSI by AC impedance, and a maximum ion conductivity of 1.44×10-5 S/cm at 30°C or 1.25×10-4 S/cm at 80°C was attained in the sample PAM 33 at the mole ratio of O : Li = 20. The DSC results indicated that Tg decreases with the increase of the proportion of AMO in the copolymer, well consistent with the ion conductivity trend. The TGA (thermogravimetric analysis) measurement revealed that this kind of copolymer electrolytes is more thermostable than their liquid counterparts.
  • ZHANG Daohong, JIA Demin, HUANG Xianbo
    The study on toughening and reinforcing of bisphenol-A epoxy resin is one of important developmental direction in the field. This paper reports a one-pot synthesis of aromatic polyester hyperbranched epoxy resin HTDE-2, an effect of HTDE-2 content on the mechanical and thermal performance of the bisphenol-A (E51)/HTDE-2 hybrid resin in detail. Fourier transform infrared (FT-IR) spectrometer, scanning electronic microscopy (SEM), differential scanning calo ri metry (DSC), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMA) and molecular simula tion technology are used to study the structure of HTDE-2, performance and toughening and reinforcing mechanism of the HTDE-2/E51 hybrid resin. It has been shown that the content of HTDE-2 has an important effect on the performance of the hybrid resin, and the performance of the HTDE-2/E51 blends has maximum with the increase in HTDE-2 content. The impact strength and fracture toughness of the hybrid resin with 9 wt-% HTDE-2 are almost 3.088 and 1.749 times of E51 performance respectively, furthermore, the tensile and flexural strength can also be enhanced about 20.7% and 14.2%, respectively. The glass transition temperature and thermal degradation temperature, however, are found to decrease to some extent.
  • XIAO Ling, WEI Xiuzhen, ZHU Baoku
    Basing on hydroxyl terminated hyperbranched poly (amine-ester)s (HPAEs), the cross-linking reactions and preparation of ester-crosslinked HPAE films were investigated using succine anhydride (SA) as crosslink reagent. It was proved that the cross-linking reaction between HPAE and SA followed a two-step mechanism. This mechanism provides an efficient route to prepare HPAE/SA cross-linked films, in which, the precursor films were prepared by casting HPAE/SA solution at a lower temperature, and then curing the films at a higher temperature. By varying SA content, the solid HPAE/SA films with different cross-linking degrees were prepared successfully. The highest tensile strength of the cross-linked film could reach 59.60 MPa. With all water contact angle smaller than 74.3°, the crosslinked films demonstrated good hydrophilic properties.
  • CHE Pengchao, HE Yaning, WANG Xiaogong
    This article reports the synthesis and photoresponsive properties of a hyperbranched azo polymer containing electron donor-acceptor type azo chromophores both in backbone and peripheral positions. For the synthesis, a hyperbranched azo precursor polymer was synthesized by step-growth polymerization of an AB2 monomer, bis[2-(N-ethylanilino)ethyl] 5-aminoisophthalate, through azo-coupling reaction. The hyperbranched precursor polymer was then reacted with the diazonium salt from 4-cyanoaniline to introduce donor-acceptor azo chromophores in the peripheral groups. The resulting azo polymers were characterized by the spectroscopic methods and thermal analysis. The photoinduced dichroism of the hyperbranched polymer was studied and its orientation order parameter was estimated to be 0.063. Thin films of the hyperbranched azo polymers were used to fabricate surface-relief-gratings (SRGs) by exposing them to an interference pattern of Ar+ laser beam at modest intensities (150 mW/cm2). The azo chromophores introduced by post-azo-coupling reaction at the para-positions of the peripheral azobenzenes shows a significant effect on the SRG inscription rate. The hyperbranched azo polymers can potentially be used for applications such as reversible optical data storage, photoswitch, sensors, and other photo-driven devices.
  • ZHANG Weixin, REN Xiangbin, YANG Zeheng, WANG Hua, WANG Qiang, HUANG Fei
    The crystalline α-MnO2 and β-MnO2 nanorods have been successfully prepared via a facile hydrothermal method from γ-MnOOH nanorods precursor, respectively. The samples were characterized by means of X-ray diff raction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscope (FESEM) and Fourier transformed infrared spectra (FTIR). The morphology and structure of γ-MnOOH nanorods precursors have a great influence on the crystal structure of the obtained products. The α-MnO2 nanorods are prepared from the 100°C γ-MnOOH precursor, while the β-MnO2 nanorods are obtained from the 150°C γ-MnOOH precursor, respectively. Besides, the catalytic activity of the prepared α-MnO2 and β-MnO2 nanorods for the H2O2 decomposition has been investigated comparatively, and the latter shows better catalytic activity.
  • ZENG Lingke, LIU Yanchun, LIU Ping′an, WANG Hui, SHUI Anze, DUAN Bilin
    The perovskite-type La0.8Sr0.2CoO3 supported on the mullite fiber porous ceramics was prepared by means of the impregnating method, and was then characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD); thus we can come to the conclusion that the perovskite-type composite oxidant can disperse on the surface of mullite fiber ceramics. The catalytic activity of the La0.8Sr0.2CoO3 for NO and CO was evaluated. The effect of the doped 0.1 wt-% PdCl2 on the catalytic activity of the perovskite-type La0.8Sr0.2CoO3 was also discussed. The results show that the conversion rates of NO and CO respectively reaches 74.5% and 99% at 601°C without doped Pd, and both reach 100% at 350°C with a little doped Pd.
  • XIE Chuang, CHEN Wei, WANG Jingkang
    CdSe nanocrystals (NCs) have great application prospects in various fields due to their novel properties. Some high-cost and toxic materials such as tri-n-octylphosphine oxide (TOPO) are used in the popular method to synthesize CdSe NCs. Based on this, a new low-cost, environment-friendly and safe solvent was introduced in the synthesis of CdSe NCs in this paper. The prepared CdSe NCs were characterized by ultraviolet-visible spectra (UV-Vis), photoluminescence (PL), transmission electron micrograph (TEM), energy disperse X-ray spectra (EDX) and X-ray diffraction (XRD). The CdSe NCs obtained which show a good PL property are monodisperse, size-tunable and of high crystallinity. It indicates that the new solvent A is a good substitute for the solvent used in the classic route and achieves a greener synthesis of CdSe NCs.
  • ZHU Xiaoqin, QIAN Ying, LU Zhifeng
    Four novel 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on push-core-pull-core-push  molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig-Horner reaction. Their chemical structures were determined to show trans-vinylene character according to infrared (IR) and 1H nuclear magnetic resonance (NMR) spectra. A very effective energy transfer from the excited units to the ?-conjugated bridging unit can enhance the two-photon absorption and two-photon fluorescence.
  • GAO Jian, REN Zhongqi, ZHANG Zeting, ZHANG Weidong
    Eight kinds of flat membranes with different micro-structures were chosen to carry out the membrane absorption experiments with CO2 and de-ionized water or 0.1 mol · L-1 NaOH solution as the experimental system. According to experimental results, the membrane pores shape (stretched pore and cylinder pore) and membrane thickness do not affect the membrane absorption process, and the membrane porosity has only little influence on membrane absorption process for slow mass transfer system. However, the influence of porosity on the membrane absorption process became visible for fast mass transfer system. Moreover, the mass transfer behavior near the membrane surface on liquid side was studied. The results show that the influence of membrane porosity on mass transfer relates to flow condition, absorption system and distance between micro-pores, etc.
  • PAN Yong, JIANG Juncheng, WANG Zhirong
    A group bond contribution model using artificial neural networks, which had the high ability of nonlinear of prediction, was established to predict the flash points of alkanes. This model contained not only the information of group property but also connectivity in molecules. A set of 16 group bonds were used as input parameters of neural networks to study the correlation of molecular structures with flash points of 44 alkanes. The results showed that the predicted flash points were in good agreement with the experimental data that the absolute mean absolute error was 6.9 K and the absolute mean relative error was 2.29%, which were superior to those of traditional group contribution methods. The method can be used not only to reveal the quantitative correlation between flash points and molecular structures of alkanes but also to predict the flash points of organic compounds for chemical engineering.
  • SHEN Jinfeng, YIN Xuan, GU Heping, Lv Xiaoping
    To investigate the influence of ultrasound pretreatment on sludge anaerobic digestion, the ultrasound disintegration of residual sludge in water treatment of petrochemical plant was studied, and the mechanisms of ultrasound and medium were introduced. Experimental results indicate that ultrasound cavitation induces the rise of sludge temperature, which improves ultrasound disintegration on sludge. U1trasound pretreatment can advance observably the quantity of chemical oxygen demand in sludge supernatant fluid (SCOD), which increases with ultrasound intensity and sonication time. The degree of ultrasound disintegration increases with the specific energy input. When the specific energy input is l0 000 kJ/kg of total dry solids, the degree of ultrasonic sludge disintegration reaches 40%.
  • HAO Yuyou, SHI Qiqi, HE Yun, ZHUANG Yingping, WANG Yonghong, ZHANG Siliang, CHU Ju, LIU Zhimin
    The present work focused on the high expression of recombinant human consensus interferon-α (cIFN) by Pichia pastoris. The cycle of glycerol feeding, the strategy of methanol feeding and the optimum pH for protein induction were studied. The optimized strategies were a 4-h glycerol-feeding period, induction pH being kept at 5.0 and methanol concentration being kept under 5 g/L. The maximum dry cell weight, cIFN production and bioactivity obtained were 168, 1.24 g/L and 5.4×107 U/mL, respectively.
  • YANG Ming, XU Yan, MU Xiaoqing, XIAO Rong
    A novel NADPH-dependent carbonyl reductase was separated from Candida parapsilosis CCTCC 203011. The enzyme gave a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which was purified through ammonium sulfate, Diethylamino Ethanol (DEAE) sepharose Fast flow (FF), phenyl-sepharose FF and blue sepharose FF chromato graphy from cell-free extract. The molecular mass of the enzyme was about 30 kDa. The optimum pH and temperature for reduction were 4.5°C and 35°C, respectively. The Cu2+ had strong restrictive effect on enzyme activity. In addition, the carbonyl reductase was an enzyme with high substrate specificity and stereo-selectivity, and showed high asymmetric reduction activity towards α-hydroxyacetophenone and ethyl 4-chloro acetoacetate. For the asymmetric reduction of ?-hydroxyacetophenone and ethyl 4-chloro acetoacetate, (S)-1-phenyl-1,2-ethanediol and (R)-ethyl 4-chloro-3-hydroxybutanoate were produced by the purified enzyme, with the 100% and 94.3% e.e. value, respectively. Therefore, the enzyme could be one of the effective biocatalysts for asymmetric synthesis of chiral alcohols. The amino acid sequences of one peptide from the purified enzyme were analyzed by LC-MASS-MASS, and the carbonyl reductase showed some identity to the hypothetical protein CaO19.10414 reported.
  • Chen Yuancai, Hao Yuan, Fu Shiyu, Zhan Huaiyu
    The comparison of pentachlorophenol (PCP) degradation was conducted under micro-aeration and anaerobic condition with three series of batch experiment, results of which indicated that during micro-aeration condition co-immobilized of anaerobic granular sludge and isolated aerobic bacterial species could enhance the efficiency of PCP reduction through the synergism of aerobes and anaerobes reductive dechlorination and exchange of metabolites within the co-immobilized granular sludge. While during anaerobic condition, there was no great difference in the three series. The specific activities experiment further confirmed that strict anaerobes were not affected over the presence of micro aeration environment. Microorganism community construction of co-immobilized anaerobic granular sludge and the mixed isolated aerobic community was also deduced. By the efficient cooperation of aerobes and anaerobes, the high efficiency removal rate of PCP was implemented.
  • YANG Zhonghua, WANG Yu, WANG Guanghui, ZENG Rong, YAO Shanjing
    The favorable microbes for the asymmetric reduction of prochiral aromatic ketones was isolated from soil using acetophenone as the sole carbon source, when the asymmetric reduction of acetophenone (ACP) to chiral ?-phenethyl alcohol (PEA) was chosen as the model reaction. Two microbe strains with excellent catalytic activity were obtained. They were Geotrichum candidum and Pichia pastoris identified by bacteria identification. The product of the asymmetric reduction of ACP catalyzed by Pichia pastoris was mainly R-PEA and that by Geotrichum candidum was mainly S-PEA. The yield and enantiomeric excesses (e.e.) could respectively reach 75% and 90% for Pichia pastoris, and 80% and 70% for Geotrichum candidum, much higher than those catalyzed by baker s yeast.
  • JIN Mingjie, HUANG He, ZHANG Kun, YAN Jie, GAO Zhen
    The analysis of flux distributions in metabolic networks has become an important approach for understanding the fermentation characteristics of the process. A model of metabolic flux analysis of arachidonic acid (AA) synthesis in Mortierella alpina ME-1 was established and carbon flux distributions were estimated in different fermentation phases with different concentrations of N-source. During the exponential, decelerating and stationary phase, carbon fluxes to AA were 3.28%, 8.80% and 6.97%, respectively, with sufficient N-source broth based on the flux of glucose uptake, and those were increased to 3.95%, 19.21% and 39.29%, respectively, by regulating the shifts of carbon fluxes via fermentation with limited N-source broth and adding 0.05% NaNO3 at 96 h. Eventually AA yield was increased from 1.3 to 3.5 g · L-1. These results suggest a way to improve AA fermentation, that is, fermentation with limited N-source broth and adding low concentration N-source during the stationary phase.