Please wait a minute...
SCI和EI收录∣中国化工学会会刊
[an error occurred while processing this directive]
Table of Content
28 October 2007, Volume 15 Issue 5
    TRANSPORT PHENOMENA & FLUID MECHANICS
    Stability of stratified gas-liquid flow in horizontal and near horizontal pipes
    GU Hanyang, GUO Liejin
    2007, 15(5):  619-625.  doi:
    Abstract ( )   PDF (326KB) ( )  
    References | Related Articles | Metrics
    A viscous Kelvin-Helmholtz criterion of the interfacial wave instability is proposed in this paper based on the linear stability analysis of a transient one-dimensional two-fluid model. In this model, the pressure is evaluated using the local momentum balance rather than the hydrostatic approximation. The criterion predicts well the stability limit of stratified flow in horizontal and nearly horizontal pipes. The experimental and theoretical investigation on the effect of pipe inclination on the interfacial instability are carried out. It is found that the critical liquid height at the onset of interfacial wave instability is insensitive to the pipe inclination. However, the pipe inclination significantly affects critical superficial liquid velocity and wave velocity especially for low gas velocities.
    Discriminated dimensional analysis versus classical dimensional analysis and applications to heat transfer and fluid dynamics
    F.Alhama, C.N.Madrid
    2007, 15(5):  626-631.  doi:
    Abstract ( )   PDF (308KB) ( )  
    References | Related Articles | Metrics
    In contrast to classical dimensional analysis, discriminated dimensional analysis assumes that spatial coordinates are dimensionally independent of each other and allows other types of geometrical quantity to be used in the dimensional basis, such as surfaces and angles. As a consequence, discriminated dimensional analysis leads to a lower number of dimensional groups, which makes the solution more precise. Besides, these discriminated groups have a clear physical meaning in terms of force and energy balances. The paper introduces this technique and provides dimensional equations for the main quantities and physical parameters of the heat transfer and fluid flow fields. Two applications are presented to demonstrate the efficiency of this method.
    SEPARATION SCIENCE & ENGINEERING
    Adsorption of protein from model wine solution by different bentonites
    SUN Xifang, LI Chun, WU Zhansheng, XU Xiaolin, REN Ling, ZHAO Hongsheng
    2007, 15(5):  632-638.  doi:
    Abstract ( )   PDF (314KB) ( )  
    References | Related Articles | Metrics
    The adsorption of protein from model wine was investigated under different temperatures, pH values, contact times, and concentrations of ethanol, by certain bentonites. The results showed that ethanol molecules could broaden the protein molecules’ channel to the interlayer of bentonite, and the maximum protein adsorption amount occurred under an ethanol concentration of 12% (by volume) and a pH value of 3.56. The increased single point Brunauer-Emmitt-Teller (BET) surface area (SBET) and adsorption pore volume (VAds) suggested a larger amount of active adsorption sites of the bentonite surface and a wider protein channel from the surface to the inner adsorption sites of bentonite, respectively. At the same time, higher methylene blue test (MBT) and swelling index (Sw) indi-cated that it was easy for the entrance of water and the absorbance of protein. Higher temperature was found favor-able to eliminate more proteins and it took about 20 to 40min to arrive at the maximum adsorption.
    Isolation and characterization of a phytotoxin from Xanthomonas campestris pv. retroflexus
    LI Mingzhi, XU Ling, SUN Ziling, LI Yongquan
    2007, 15(5):  639-642.  doi:
    Abstract ( )   PDF (146KB) ( )  
    References | Related Articles | Metrics
    A phytotoxin from Xanthomonas campestris pv. retroflexus was isolated using a chromatographer and HPLC, and the components were identified to be a mixture of minor molecular compounds including organic acids and cyclo-(proline-phenylalanine). The greenhouse cultivation test was used to determine the influence of the isolated fractions on the growth of target weed redroot pigweed (Amaranthus retroflexus L). The experimental results demonstrated that the cyclo-(Pro-Phe) had the weed inhibit activity obviously on dicotyledonous weed and the mixture with six organic acids showed stronger bioactivity. Further, greenhouse and field test were processed, and the test showed that the use of the toxin appeared to have the potential to be developed further as a bioherbicide system to control weedy grasses.
    Preparation of thin palladium composite membranes and application to hydrogen/nitrogen separation
    ZHANG Ke, GAO Huiyuan, RUI Zebao, LIN Yuesheng, LI Yongdan
    2007, 15(5):  643-647.  doi:
    Abstract ( )   PDF (414KB) ( )  
    References | Related Articles | Metrics
    Thin palladium composite membranes were prepared by modified electroless plating method on α-alumina supports and a dense Pd/α-Al2O3 composite membrane with high hydrogen flux, good selectivity for hydrogen was obtained. It was tested in a single gas permeation system for hydrogen permeance and hydrogen selectivity over nitrogen. The hydrogen permeance of the corresponding membrane was as high as 2.45 10-6mol•m-2•s-1•Pa-1 and H2/N2 selectivity over 700 at 623K and a pressure difference of 0.1MPa. The main resistance of the composite membrane to H2 permeation lies in the aluminum ceramic support rather than the thin Pd layer.
    Effects of solvent and impurity on crystal habit modification of 11α-hydroxy-16α,17α-epoxyprogesterone
    NIE Qiang, WANG Jingkang, WANG Yongli, BAO Ying
    2007, 15(5):  648-653.  doi:
    Abstract ( )   PDF (629KB) ( )  
    References | Related Articles | Metrics
    The effects of solvent and impurity on the crystal habit of 11α-hydroxy-16α, 17α-epoxyprogesterone (HEP) grown from solution were studied by scanning electron microscope. Long prismatic crystals were produced when HEP was crystallized from pure acetone and N,N-dimethylformamide, while blocky crystals were produced from pure chloroform by cooling crystallization. One kind of isomorphic impurity, 16α,17α-epoxyprogesterone (EP) was selected to examine its effect on the HEP crystal habit. When the content of EP in the mother liquor is very high (55.45%, solvent free basis), the habit of produced HEP crystals was greatly modified from prismatic to octahedral. The differential scanning calorimetry and X-ray powder diffraction analyses showed that the change of crystal habit was originated from the crystal structure modification.
    REACTION KINETICS, CATALYSIS AND……
    Application of liquid solid semi-moving bed to fractionation of cesium ion in wastewater
    XU Cong, FENG Xiaogui, JING Shan
    2007, 15(5):  654-660.  doi:
    Abstract ( )   PDF (214KB) ( )  
    References | Related Articles | Metrics
    A liquid solid semi-moving bed with non-mechanical particle transport system is proposed and used for fractionation of cesium ion in wastewater. The particle transport system, which consists of a suction chamber, a mixing chamber, a nozzle and a riser tube, is designed to be controlled completely by hydraulic force. Experiments show that continuous feeding and discharging of resin can be realized by the transport system. The removal of ce-sium ion from wastewater is realized. The concentration of cesium ion in effluent liquid remains below 0.1g•L-1 (the initial concentration is 5.3g•L-1) during the 73 hours’ experiment. The average exchange capacity of resin dis-charged from the bed is 0.57mmol•(g dry resin) -1, which is close to the saturated capacity of 0.65mmol•g-1. And it is also proved that the non-homogeneity of particle vertical velocity along the radial direction can seriously influ-ence the ion-exchange process.
    Cationic ring opening polymerization of octamethylcyclotetrasiloxane initiated by acid treated bentonite
    CHEN Bi, ZHAN Xiaoli, YI Lingmin, CHEN Fengqiu
    2007, 15(5):  661-665.  doi:
    Abstract ( )   PDF (306KB) ( )  
    References | Related Articles | Metrics
    Cationic ring opening polymerization of octamethylcyclotetrasiloxane (D4) initiated by acid treated bentonite was investigated. The experimental conditions were chosen on the basis of preliminary experiments. Higher temperature was found beneficial for the reaction process while stirring intensity beyond a certain level showed no obvious effect on the reaction rate. Polymers were characterized by Fourier transform infrared, proton nuclear magnetic resonance (1H-NMR) and gel permeation chromotography. The width of molecular mass distribution was found ranging between 1.2 and 1.4, which is extraordinarily narrow compared with that of cationic polymerizations reported elsewhere (>1.9). The results were believed due to the absence of free proton and counter ion which simplifies the polymerization process and the huge steric hindrance provided by bentonite particles which keeps the propagation of polysiloxane onto the surface of bentonite particles in a much more regular way. A feasible mecha-nism is proposed and seems to be supported well by experiments. Additionally, from the results of α, ω-dihydrogen terminated polysiloxanes prepared, the possibility of applying this potential environmentally friendly heterogeneous catalyst in industrial polymerization of cyclosiloxanes is anticipated.
    Kinetics of non-catalyzed decomposition of d-xylose in high temperature liquid water
    JING Qi, LÜ, Xiuyang
    2007, 15(5):  666-669.  doi:
    Abstract ( )   PDF (119KB) ( )  
    References | Related Articles | Metrics
    The kinetics of non-catalyzed decompositions of xylose and its decomposition product furfural in high temperature liquid water (HTLW) was studied for temperature from 180 to 220℃ and under pressure of 10MPa. The main products of xylose decomposition were furfural and formic acid, and furfural further degraded to formic acid under HTLW condition. With the assumption of first order kinetics equation, the evaluated activation energy of xylose and furfural decomposition was 123.27kJ•mol-1 and 58.84kJ•mol-1, respectively.
    Catalytic activity of the black liquor and calcium mixture in CO2 gasification of Fujian anthracite
    Gul-e-Rana JAFFRI, ZHANG Jiyu
    2007, 15(5):  670-679.  doi:
    Abstract ( )   PDF (431KB) ( )  
    References | Related Articles | Metrics
    CO2 gasification of Fuijian high-metamorphous anthracite with black liquor (BL) and/or mixture of BL and calcium stuff (BL+Ca) as catalyst was studied by using a thermogravimetry under 750—950℃ at ambient pressure. When the coal was impregnated with an appropriate quantity of Ca and BL mixture, the catalytic activity of CO2 gasification was enhanced obviously. With a loading of 8%Na-BL+2%Ca, the carbon conversion of three coal samples tested reaches up to 92.9%—99.3% at 950℃ within 30min. The continuous formation of alkali surface compounds such as ([-COM], [-CO2M]) and the presence of exchanged Ca, such as calcium phenolate and calcium carboxylates (COO)2Ca, contribute to the increase in catalytic efficiency, and using BL+Ca is more efficient than that adding BL only. The homogeneous model and shrinking-core model were applied to correlate the data of conversion with time and to estimate the reaction rate constants under different temperature. The corresponding re-action activation energy (Ea) and pre-exponential factor of three anthracites were estimated. It is found that Ea is in the range from 73.6 to 121.4kJ•mol-1 in the case of BL+Ca, and 74.3 to 104.2kJ•mol-1 when only BL was used as the catalyst, both of which are much less than that from 143.5 to 181.4kJ•mol-1 if no catalyst used. It is clearly demonstrated that both of BL+Ca mixture and BL could be the source of cheap and effective catalyst for coal gasi-fication.
    Alkylation of toluene with 1,3-pentadiene over [bupy]BF4-AlCl3 ionic liquid catalyst
    TIAN Li, CAO Fahai, FANG Dingye, GUO Shizhuo
    2007, 15(5):  680-682.  doi:
    Abstract ( )   PDF (154KB) ( )  
    References | Related Articles | Metrics
    The alkylation of toluene with 1,3-pentadiene to produce pentyltoluene was carried out to obtain 2,6-dimethylnaphalene, which is an important intermediate during the production of 2,6-naphthalene dicarboxylic acid. Based on our previous work using anhydrous AlCl3 as catalyst, [bupy]BF4-AlCl3 ionic liquids were employed to catalyze the reaction of 1,3-pentadiene with toluene. The experimental results show that [bupy]BF4-AlCl3 ionic liquids are suitable for the reaction especially when the molar ratio of AlCl3 to [bupy]BF4 is 1.75︰1, and the reaction could proceed at the temperature as low as 0℃. It could be as active as pure AlCl3, but much more environmentally friendly.
    SYSTEM ENGINEERING
    Multiobjective optimization of simulated moving bed by tissue P system
    HUANG Liang, SUN Lei, WANG Ning, JIN Xiaoming
    2007, 15(5):  683-690.  doi:
    Abstract ( )   PDF (389KB) ( )  
    References | Related Articles | Metrics
    The binaphthol enantiomers separation process using simulation moving bed technology is simulated with the true moving bed approach (TMB). In order to systematically optimize the process with multiple productive objectives, this article develops a variant of tissue P system (TPS). Inspired by general tissue P systems, the special TPS has a tissue-like structure with several membranes. The key rules of each membrane are the communication rule and mutation rule. These characteristics contribute to the diversity of the population, the conquest of the multimodal of objective function, and the convergence of algorithm. The results of comparison with a popular algorithm—the non-dominated sorting genetic algorithm 2(NSGA-2) illustrate that the new algorithm has satisfactory performance. Using the algorithm, this study maximizes synchronously several conflicting objectives, purities of different products, and productivity.
    Nonlinear model predictive control based on support vector machine with multi-kernel
    BAO Zhejing, PI Daoying, SUN Youxian
    2007, 15(5):  691-697.  doi:
    Abstract ( )   PDF (314KB) ( )  
    References | Related Articles | Metrics
    Multi-kernel-based support vector machine (SVM) model structure of nonlinear systems and its specific identification method is proposed, which is composed of a SVM with linear kernel function followed in series by a SVM with spline kernel function. With the help of this model, nonlinear model predictive control can be trans-formed to linear model predictive control, and consequently a unified analytical solution of optimal input of multi-step-ahead predictive control is possible to derive. This algorithm does not require online iterative optimiza-tion in order to be suitable for real-time control with less calculation. The simulation results of pH neutralization process and CSTR reactor show the effectiveness and advantages of the presented algorithm.
    A novel robust nonlinear dynamic data reconciliation
    GAO Qian, YAN Weiwu, SHAO Huihe
    2007, 15(5):  698-702.  doi:
    Abstract ( )   PDF (275KB) ( )  
    References | Related Articles | Metrics
    Outlier in one variable will smear the estimation of other measurements in data reconciliation (DR). In this article, a novel robust method is proposed for nonlinear dynamic data reconciliation, to reduce the influence of outliers on the result of DR. This method introduces a penalty function matrix in a conventional least-square objective function, to assign small weights for outliers and large weights for normal measurements. To avoid the loss of data information, element-wise Mahalanobis distance is proposed, as an improvement on vector-wise distance, to construct a penalty function matrix. The correlation of measurement error is also considered in this article. The method introduces the robust statistical theory into conventional least square estimator by constructing the penalty weight matrix and gets not only good robustness but also simple calculation. Simulation of a continuous stirred tank reactor, verifies the effectiveness of the proposed algorithm.
    THERMODYNAMICS AND CHEMICAL……
    Densities and viscosities of the quaternary system mannitol-sorbitol-D-glucose-H2O and its ternary subsystems at 298.15K
    LIU Yansheng, SHI Mingxian, CAO Rui, ZHANG Yaohui, HU Yufeng
    2007, 15(5):  703-709.  doi:
    Abstract ( )   PDF (302KB) ( )  
    References | Related Articles | Metrics
    To check the applicabilities of the simple density equation and viscosity equation in the semi-ideal solution theory to nonelectrolyte solutions, the densities and viscosities were measured for the quaternary system mannitol-sorbitol-D-glucose-H2O and its ternary subsystems mannitol-D-glucose-H2O and sorbitol-D-glucose-H2O at 298.15K. The results were used to test the applicability of the simple equations for the density and viscosity of the multicomponent nonelectrolyte solution. The agreements between the predicted and measured results are good.
    Solid-liquid equilibria of Benzoic acid derivatives in 1-octanol
    JIA Qingzhu, MA Peisheng, MA Shaona, WANG Chang
    2007, 15(5):  710-714.  doi:
    Abstract ( )   PDF (287KB) ( )  
    References | Related Articles | Metrics
    The solid-liquid equilibrium of benzoic acid derivatives in 1-octanol was first determined in this article. Using a laser monitoring observation technique, the solubility data of o-amino-benzoic acid, p-amino-benzoic acid, o-chloro-benzoic acid, and m-nitro-benzoic acid in 1-octanol were measured by the polythermal method in the temperature range of 20—50℃. The experimental data were regressed with the Wilson equation and the λH equa-tion. The experimental results showed that the solubility of the four chemicals in 1-octanol increased significantly with temperature. The results indicate that the molecular structure and interactions affect the solubility significantly. The solubility order of the benzoic acid derivatives is as follows: m-nitro-benzoic acid>o-chloro-benzoic acid>o-amino-benzoic acid>p-amino-benzoic acid. Both the Wilson equation and λH equation are in good agreement with the experimental data.
    Estimation of octanol-water partition coefficient of chloride hydrocarbon by group contribution method
    LIANG Yinghua, CHEN Hongping
    2007, 15(5):  715-719.  doi:
    Abstract ( )   PDF (124KB) ( )  
    References | Related Articles | Metrics
    A novel method named two-level group contribution (GC-K) method for the estimation of octanol-water partition coefficient (Kow) of chloride hydrocarbon is presented. The equation includes only normal boiling points and molecular weight of compounds. Group contribution parameters of 12 first-level groups and 7 second-level groups for Kow are obtained by correlating experimental data of three types including 57 compounds. By comparing the estimation results of the first-level with that of the two-level groups, it was observed that the latter is better with the addition of the modification of proximity effects. When compared with Marrero’s three-level group contribution approach and atom-fragment contribution method (AFC), the accuracy of the average relative error of GC-K by first-level groups is 7.20% and is preferred to other methods.
    BIOTECHNOLOGY & BIOENGINEERING
    Space-flight mutation of streptomyces gilvosporeus for enhancing natamycin production
    LIANG Jingle, LIN Jianping, XU Zhinan, SU Wei, CEN Peilin
    2007, 15(5):  720-724.  doi:
    Abstract ( )   PDF (436KB) ( )  
    References | Related Articles | Metrics
    Mutants of the strain producing natamycin, Streptomyces gilvosporeus, were obtained after space-flight mutation. With respect to the sand spores and slant spores, the mutation ratios were up to 67.6% and 78.3% and the survival ratio was 43.1% and 3.0%, respectively. An improved mutant producing natamycin, S. gilvosporeus LK-45, was screened, which showed natamycin productivity of 1420mg•L-1. A mutant resistant to 2-deoxy glucose, S. gil-vosporeus LK-119, was further obtained using a rational screening procedure. The natamycin productivity of 1940mg•L-1 was achieved when glucose was used as the carbon source.
    Integrative extraction of ergosterol, (1→3)-α-D-glucan and chitosan from Penicillium chrysogenum mycelia
    WANG Tianqi, LI Hanxiang, WANG Manyi, TAN Tianwei
    2007, 15(5):  725-729.  doi:
    Abstract ( )   PDF (349KB) ( )  
    References | Related Articles | Metrics
    Ergosterol,(1→3)-α-D-glucan and chitosan are important biomaterials. In this research, a process has been developed to integratively extract ergosterol, (1→3)-α-D-glucan, and chitosan from Penicillium chrysongenum mycelium. First, the mycelia are pretreated with 0.1mol•L-1 of NaOH. After recovery by centrifugation, the solid portion is made to undergo saponification and deacetylation reactions by addition of 2mol•L-1 NaOH and ethanol. After reaction, extraction is carried out by addition of petroleum ether, which separates the reaction mixture into two phases. The upper layer of petroleum ether contains extracted ergosterol, and the bottom layer of NaOH solu-tion contains (1→3)-α-D-glucan; the chitosan is on the mycelia residuum. After isolation, the recovery yield of er-gosterol is 0.52% of dry mycelium. That of (1→3)-α-D-glucan is about 8.2%; and chitosan is 5.7% with 86% deacetylation. The compositions have been characterized by IR, HPLC analyses.
    PROCESS AND PRODUCT TECHNOLOGY
    Dynamics of spreading of liquid on solid surface
    WANG Xiaodong, PENG Xiaofeng, DUAN Yuanyuan, WANG Buxuan
    2007, 15(5):  730-737.  doi:
    Abstract ( )   PDF (379KB) ( )  
    References | Related Articles | Metrics
    Based on assuming that there is the precursor film in the front of the apparent contact line (ACL), a model was proposed to understand the dynamic wetting process and associated dynamic contact angle. The present model indicated that a new dimensionless characteristic parameter, λ, affects the dynamic wetting process and associated dynamic contact angle as well. However, the previous model suggested that the dynamic contact angle is dependent on the capillary number and static contact angle only. An experimental investigation was conducted to measure the dynamic wetting behavior of silicon oil moving over glass, aluminum and stainless steel surfaces. It concluded that when the value of λ was selected as 0.07, 0.16 and 0.35 for glass, aluminum and stainless steel, respectively, the experimental results were in good accordance with the prediction of the model. Furthermore, the comparison of the model with Ström’s experimental data showed that λ is independent on the species of liquids. Apparently, λ should be interpreted as the effect of the solid surface properties on the dynamic wetting process. Meanwhile, it is found in the present experiment that the Hoffman-Voinov-Tanner law, which is valid at very low capillary number (Ca 1 or θD<10°) recommend by Cazabat, still holds for higher contact angles, even up to 70°—80°. This is explained by the present model very well.
    Effect of increasing course of temperature and pressure on polypropylene degradation in supercritical water
    SU Lei, WU Xuehua, LIU Xiuru, CHEN Liying, CHEN Keyu, HONG Shiming
    2007, 15(5):  738-741.  doi:
    Abstract ( )   PDF (206KB) ( )  
    References | Related Articles | Metrics
    The effect of increasing course of temperature and pressure on polypropylene (PP) degradation in supercritical water was investigated for developing a process of recycling waste plastic. A group of experiments was carried out in a reaction system at a pressure of 26MPa, temperature of 380℃ or 400℃ for 30min, 70min, and 120min by Course One (the increasing course of temperature and pressure is via gaseous regions to supercritical regions), and the other group was carried out at corresponding holding conditions by Course Two (the increasing course of temperature and pressure is via liquid regions to supercritical regions). The time of the increasing courses was about 30min. Products were analyzed by Ostward-type viscometer, gaseous chromatography, and mass spectrometers (GC/MS). Characterization results suggested that different increasing courses of temperature and pressure would give rise to different results, although they were treated under the similar holding conditions. It was also found that Course Two was more effective on PP degradation in supercritical water.
    Preparation and characterization of alkaline resistant porous ceramics from potassium titanate whiskers
    ZHOU Yaxin, LIU Chang, HE Ming, YANG Zhuhong, FENG Xin, LU Xiaohua
    2007, 15(5):  742-747.  doi:
    Abstract ( )   PDF (556KB) ( )  
    References | Related Articles | Metrics
    The preparation and characterization of alkaline resistant porous ceramics from potassium titanate whiskers are studied. K2Ti4O9 whiskers in the whisker preforms (mixtures of K2Ti6O13 and K2Ti4O9) were completely converted to K2Ti6O13 at 960℃. The alkaline resistance as well as the change in bending strength, porosity and permeability of the ceramics was investigated by altering the composition of the preforms in which the content of K2Ti6O13 whiskers was higher than 50% (molar fraction). The alkaline resistance of the porous K2Ti6O13 ceramics is found much higher than that of Al2O3 in caustic NaOH solutions, and further study indicates that the K2Ti6O13 ceramics can be stably used in solutions of pH>2.0. The bending strength increases initially with the content of the raw K2Ti6O13 in the preforms up to 66% (molar fraction) and then decreases, contrary to the behaviors of porosity and permeability. The values of bending strength, porosity and permeability of the ceramics prepared from the preform of 80% (molar fraction) raw K2Ti6O13 whiskers are respectively 56MPa, 29.4% and 330L•m-2•h-1, which are comparable to those of the porous Al2O3 ceramics.
    Orientation-dependent hydrodynamic instabilities from chemo-Marangoni cells to large scale interfacial deformations
    SHI Ying, Kerstin Eckert
    2007, 15(5):  748-753.  doi:
    Abstract ( )   PDF (516KB) ( )  
    References | Related Articles | Metrics
    The interplay between chemistry and interfacial-tension-driven hydrodynamic instabilities has been studied experimentally. The system on hand consists of two immiscible liquids separated along an initially plane interface at which an interfacial reaction takes place to produce in situ a surfactant. It is identified that the dynamics of the system depends on the orientation of the Hele-Shaw cell with respect to the vector of gravity. If the Hele-Shaw cell is placed vertically, Marangoni cells with vigorous convection develop in both phases along a nearly planar interface. However, if the Hele-Shaw cell is tilted off the gravity, the instabilities in the system are characterized by the large scale interfacial deformation with a spatio-temporal periodicity together with the chemo-Marangoni convection. The focus is on the exploration of the transition from the cellular mode to the large scale interfacial deformation.
    Morphology control of anatase TiO2 by surfactant-assisted hydrothermal method
    WANG Fumin, SHI Zhansheng, GONG Feng, JIU Jinting, ADACHI Motonari
    2007, 15(5):  754-759.  doi:
    Abstract ( )   PDF (1114KB) ( )  
    References | Related Articles | Metrics

    By hydrolysing titanium isopropoxide in a long hydrocarbon chain surfactant-containing solution, TiO2 fine particles with a diversity of well-defined morphologies was synthesized in this study by a hydrothermal route. The structural change during the formation process was monitored by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. TiO2 with various morphologies such as particle, sheet, rod, tube and flower-like shape was obtained by carefully controlling the preparation conditions. The experimental re-sults show that the pH value is crucial for shape control of the produced TiO2 because it can change the charge state of the surfactant in the solution and the adsorption potential of the surfactant on the TiO2 surface. The shape evolvement of anatase TiO2 was elucidated by quenching the reaction at different stage and the formation mecha-nism of different shaped TiO2 was suggested.

    RESEARCH NOTES
    Production of human epidermal growth factor in fed-batch culture of acetate-tolerant Escherichia coli
    HAN Yun, LI Zhimin, DU Peng, GAN Renbao, YE Qin
    2007, 15(5):  760-764.  doi:
    Abstract ( )   PDF (267KB) ( )  
    References | Related Articles | Metrics
    An acetate-tolerant mutant of Escherichia coli DH5α, DA19, was used for secretory production of human epidermal growth factor (hEGF) whose expression was under the control of phoA promoter. The recombinant cells were cultured in a chemically defined medium, and glucose was added at different specific provision rates during the growth and expression phases. It was found that pH had a significant effect on the extracellular hEGF production. The extracellular hEGF concentration was 75.5mg•L-1, 5.2-fold of the level reached at pH 7.0, even though more acetate was produced. Nitrogen source was limited in the later growth phase. Supplementation of ammonium promoted the consumption of phosphate and reduced the time to exhaust phosphate, but the extracellular hEGF production was similar to that without supplementation of ammonium.
    Correlation of vapour liquid equilibria of binary mixtures using artificial neural networks
    Hajir Karimi, Fakhri Yousefi
    2007, 15(5):  765-771.  doi:
    Abstract ( )   PDF (118KB) ( )  
    References | Related Articles | Metrics
    In this paper, a back propagation artificial neural network (BP-ANN) model is presented for the simultaneous estimation of vapour liquid equilibria (VLE) of four binary systems viz chlorodifluoromethan-carbondioxide, trifluoromethan-carbondioxide, carbondisulfied-trifluoromethan and carbondisulfied-chlorodifluoromethan. VLE data of the systems were taken from the literature for wide ranges of temperature (222.04—343.23K) and pressure (0.105 to 7.46MPa). BP-ANN trained by the Levenberg-Marquardt algorithm in the MATLAB neural network toolbox was used for building and optimizing the model. It is shown that the established model could estimate the VLE with satisfactory precision and accuracy for the four systems with the root mean square error in the range of 0.054—0.119. Predictions using BP-ANN were compared with the conventional Redlich-Kwang-Soave (RKS) equation of state, suggesting that BP-ANN has better ability in estimation as compared with the RKS equation (the root mean square error in the range of 0.115—0.1546).
    Simultaneous synthesis of dimethyl carbonate and poly (ethylene terephthalate) using alkali metals as catalysts
    ZHANG Dan, WANG Qingyin, YAO Jie, WANG Yue, ZENG Yi, WANG Gongying
    2007, 15(5):  772-774.  doi:
    Abstract ( )   PDF (79KB) ( )  
    References | Related Articles | Metrics
    Dimethyl carbonate (DMC) and poly(ethylene terephthalate) was simultaneously synthesized by the transesterification of ethylene carbonate (EC) with dimethyl terephthalate (DMT) in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also stud-ied. When the reaction was carried out under the following conditions: the reaction temperature 250℃, molar ratio of EC to DMT 3︰1, reaction time 3h, and catalyst amount 0.004 (molar ratio to DMT), the yield of DMC was 68.9%.