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Comparison between two commercial uranium resins and a uranyl sulphate imprinted resin based on self-assembling MIT
LIU Yaochi, XU Wei, XU Weijian, LIU Hanmao, ZHANG Xiaowen
Front. Chem. Sci. Eng.. 2007, 1 (4): 327-331.
https://doi.org/10.1007/s11705-007-0059-8
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.
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Surface modification of titanium dioxide for electrophoretic particles
PENG Xuhui, LE Yuan, BIAN Shuguang, LI Woyuan, WU Wei, DAI Haitao, CHEN Jianfeng
Front. Chem. Sci. Eng.. 2007, 1 (4): 338-342.
https://doi.org/10.1007/s11705-007-0061-1
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.
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Synthesis of copolymers of 3-acryloyloxymethyl-3′-methyloxetane and 3-(2-(2-(2-Methoxyethylenoxy)ethylenoxy)ethylenoxy)-3′-methyloxetane and their ionic conductivity properties
YE Lin, ZHAO Yumei, FENG Zengguo, BAI Ying, WU Feng
Front. Chem. Sci. Eng.. 2007, 1 (4): 343-348.
https://doi.org/10.1007/s11705-007-0062-0
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.
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Bisphenol-A epoxy resin reinforced and toughened by hyperbranched epoxy resin
ZHANG Daohong, JIA Demin, HUANG Xianbo
Front. Chem. Sci. Eng.. 2007, 1 (4): 349-354.
https://doi.org/10.1007/s11705-007-0063-z
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.
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Hydrothermal synthesis of crystalline α-/β-MnO2 nanorods via γ-MnOOH nanorod precursors
ZHANG Weixin, REN Xiangbin, YANG Zeheng, WANG Hua, WANG Qiang, HUANG Fei
Front. Chem. Sci. Eng.. 2007, 1 (4): 365-371.
https://doi.org/10.1007/s11705-007-0066-9
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.
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Synthesis and characterization of 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles with two-photon fluorescence properties
ZHU Xiaoqin, QIAN Ying, LU Zhifeng
Front. Chem. Sci. Eng.. 2007, 1 (4): 381-384.
https://doi.org/10.1007/s11705-007-0069-6
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.
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Experimental studies on the influence of porosity on membrane absorption process
GAO Jian, REN Zhongqi, ZHANG Zeting, ZHANG Weidong
Front. Chem. Sci. Eng.. 2007, 1 (4): 385-389.
https://doi.org/10.1007/s11705-007-0070-0
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.
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High-expression of recombinant human concensus interferon-α by Pichia pastoris
HAO Yuyou, SHI Qiqi, HE Yun, ZHUANG Yingping, WANG Yonghong, ZHANG Siliang, CHU Ju, LIU Zhimin
Front. Chem. Sci. Eng.. 2007, 1 (4): 399-403.
https://doi.org/10.1007/s11705-007-0073-x
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.
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Purification and characterization of a novel carbonyl reductase with high stereo-selectivity
YANG Ming, XU Yan, MU Xiaoqing, XIAO Rong
Front. Chem. Sci. Eng.. 2007, 1 (4): 404-410.
https://doi.org/10.1007/s11705-007-0074-9
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.
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Metabolic flux analysis on arachidonic acid fermentation
JIN Mingjie, HUANG He, ZHANG Kun, YAN Jie, GAO Zhen
Front. Chem. Sci. Eng.. 2007, 1 (4): 421-426.
https://doi.org/10.1007/s11705-007-0077-6
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.
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