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Table of Content

    25 September 2010, Volume 38 Issue 9
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    Electronics, Communication & Automation Technology
    Anti-Harmonic Lock Delay-Locked Loop
    Yao Ruo-he Chen Zhong-meng
    2010, 38(9):  1-6.  doi:10.3969/j.issn.1000-565X.2010.09.001
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    In order to avoid the failure lock and harmonic lock in conventional delay-locked loop（DLL） during wide-range operation,a start control circuit is added in the conventional DLL structure to charge the power supply by the loop filter capacitor in the power-on stage.So,the intitial delay of voltage-controlled delay line（VCDL） is minimized after the power-on and is controlled to be less than one period of the input reference clock.Then,a novel phase detector with switches is designed,which divides the locking process of DLL into a coarse tuning stage and a fine one.In the coarse tuing stage,the delay of VCDL monotonically increases,while in the fine stage,it is fine tuned till to one period of the input reference clock.Thus,the failure lock and harmonic lock during wide-range operation are successfully avoided and the the locking time of DLL is reduced.Finally,a DLL is designed and simulated under the power supply of 1.2V with GSMC 0.13μm 1P7M CMOS technology,with an operation frequency of 300～500MHz and a power consumption of less than 3mW being achieved.

    Adaptive Resource Allocation Strategy of Relay OFDMA Systems
    Zhang Xin Ye Wu Feng Sui-li Zhuang Hong-cheng
    2010, 38(9):  7-12.  doi:10.3969/j.issn.1000-565X.2010.09.002
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    In this paper,first,the problem of resource allocation of relay OFDMA systems is described as a mathematical model with power-limited access nodes and maximum system capacity,which meets the requirements of miminum rate of each user.Then,a resource allocation algorithm based on dual decomposition is proposed,which decomposes the problem into several subproblems of subcarriers,thus effectively recuding the calculation complexity.By solving the subproblems,optimal schemes of relay node selection,power allocation and subcarrier assignment can be obtained.Simulated results show that the proposed algorithm effectively improves the system capacity and simultaneously meets the rate requiremnets of each user.

    Genetic Algorithm-Based Dynamic Planning and Management of Reconfigurable System
    Xu Yu-bin Ding Zhe Sha Xue-jun
    2010, 38(9):  13-19.  doi:10.3969/j.issn.1000-565X.2010.09.003
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    The dynamic planning and management（DPM） of reconfigurable system is regarded as a complicated combinatorial optimization problem.In this paper,a novel DPM method based on genetic algorithm is presented,which enables the fast convergence in the valid solution space and meets the real-time requirements of DPM.Moreover,a novol traffic distribution planning method based on the spectral efficiencies offered by different RATs is pre-sented to improve the overall spectral efficiency of the reconfigurable system.Simulated results demonstrate that the DPM method based on the proposed traffic distribution planning is of a spectral efficiency gain of 38.1%,and that it outperforms the one based on the conventional traffic distribution planning in terms of overall spectral efficiency.

    Multiple Access Scheme of Ultra-Wideband System in Fractional Fourier Transform Domain
    Qiu Xin Sha Xue-jun Ning Xiao-yan
    2010, 38(9):  20-24.  doi:10.3969/j.issn.1000-565X.2010.09.004
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    Proposed in this paper is a multiple access scheme based on fractional Fourier transform（FrFT） to improve the bit error rate（BER） performance of ultra-wideband（UWB） system.In this scheme,with the combination of TDMA（Time Division Multiple Access） and the utilization of phase change in waveform selection,a set of orthogonal pulse waveforms are designed and applied to the ultra-wideband system.Then,based on the energy-aggregating characteristics of the signal in the order-FrFT domain,filtering is conducted to reduce the multiple access interference.Simulated results indicate that the proposed scheme effectively improves the system capacity and the orthogonality among pulse waveforms,and that the filtering in FrFT domain further improves the BER perfor-mance of the system.

    Computation Algorithm of Transmission Rate of Cognitive Radio Based on Water-Level Adjustment
    Liu Yu-tao Tan Xue-zhi Liu Shuai
    2010, 38(9):  25-29,51.  doi:10.3969/j.issn.1000-565X.2010.09.005
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    By means of the wireless transmission model of Rayleigh fading,people often use the utility function of cognitive users to solve the problem of channel programming in cognitive radio networks and to further obtain the transmission rate.As the final communication utility only relates to the water-level when both the total transmission power and the bit error rate（BER） of cognitive users are constrained,a algorithm of power allocation based on water-level adjustment is proposed,through which power and subcarriers can be assigned reasonably and the transmission rate can be finally obtained.Theoretical and simulative results show that the proposed algorithm is of low computation complexity and high utility close to that of the optimal algorithm,and that the adjustment factor only relates to the convergence rate of the algorithm,but not to the total utility and channel allocation results of cognitive users.

    Fault-Tolerant Algorithm Based on Active Request and Dynamic Load Distribution for CAN System
    Cao Xiao-hua Zhou Yong
    2010, 38(9):  30-34.  doi:10.3969/j.issn.1000-565X.2010.09.006
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    When the controller area network（CAN） bus is applied to a distributed overloading system,the reliability and real-time property of the system can not be guaranteed.Fault-tolerant algorithms are the important means to improve the system performances.In this paper,several fault-tolerant algorithms are analyzed and compared,and an approach of introducing active request and dynamic load distribution in the redundant services is proposed,based on which an effective fault-tolerant algorithm for CAN systems is put forward.In this algorithm,CAN nodes decide whether to actively request the task to be a redundant server according to their load status,and the management system assigns the load to each redundant server according to the load and the current status of node hosts and changes the number of redundant servers dynamically.A mathematical model of the proposed algorithm is also established,and some illustrations are finally presented to compare the algorithm with RAWA fault-tolerant algorithms.The results show that the proposed algorithm with high performance is applicable to the control system with high reliability and good real-time property.

    Impulsive Stabilization of Stochastic Functional Differential Systems
    Yao Feng-qi Deng Fei-qi Peng Yun-jian
    2010, 38(9):  35-39.  doi:10.3969/j.issn.1000-565X.2010.09.007
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    In this paper,first,the concepts of mean-square uniformly asymptotic stabilization by impulses and by periodical impulses are proposed for general stochastic functional differential systems.Next,the sufficient criteria for mean-square uniformly asymptotic stabilization of the stochastic systems by periodical impulses are put forward by using Lyapunov functions and the asymptotic stability of a scalar linear impulsive delay differential system.Then,a specific design method of impulsive controllers is presented,in which the impulse functions are chosen as proportional functions,and the intervals of impulsive moment depend on system parameters and the selected proportional coefficients of impulse functions.Finally,a numerical example is presented to verify the effectiveness of the designed controllers.

    Chemistry & Chemical Engineering
    Decomposition Kinetics and Mechanism of Alkaline Hydrogen Peroxide with Transition Metals
    Zhang Xue-jin Li You-ming Lu Rui-jiang
    2010, 38(9):  40-45.  doi:10.3969/j.issn.1000-565X.2010.09.008
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    Trace transition metals were introduced in the catalytic decomposition of alkali hydrogen peroxide at va-rious pH values,and the corresponding decomposition kinetics and mechanism were investigated.The results indicate that the decomposition of hydrogen peroxide follows the quasi-first-order law in alkaline conditions,that the quasi-first-order rate constant of the alkali decomposition,kobs,increases with the pH value when 10.0≤pH≤11.6 but decreases when pH11.6,and that kobs reaches the maximum 0.0922 min-1 at 70℃ and pH11.6.Moreover,the effects of pH value and reaction time on the size of transition-metal colloidal particles were also discussed,finding that the average sizes of Mn 2＋ and Fe 3＋ colloidal particles increase with the reaction time and the pH value,respectively.Thus,it is concluded that the decomposition of alkaline hydrogen peroxide is due to the catalytic decomposition of transition metal colloids and the alkaline ionization of hydrogen peroxide.

    Extractives of High-Yield Bamboo Pulp and Their Effects on H2O2 Bleaching
    Liang Chen Zhan Huai-yu Li Bing-yun Fu Shi-yu
    2010, 38(9):  46-51.  doi:10.3969/j.issn.1000-565X.2010.09.009
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    This paper deals with the extractives of high-yield Neosinocalamus sulfonated chemimechanical pulp（SCMP） and their effects on the hydrogen peroxide bleaching.The results show that the extractives from Neosinocalamus SCMP in benzene-alcohol,dichloromethane and methanol are all in low content,that the extractives mainly contain fatty acids and steroids,as well as some substances producing UV absorption at about 330nm,that the brightness of peroxide-bleached pulp after the extraction increases by more than 6%,and by 9%ISO especially after the benzene-alcohol extraction,and that the yellowish phenomenon of the bleached pulp lightens to a degree of 37.3% at most and the heat-induced yellowing value decreases by 65.8% at most.

    Lignin Structure of Bamboo Bambusa chungii SCMP and Its Change During Bleaching and Aging
    Li Bing-yun Zhan Huai-yu Liang Chen Fu Shi-yu
    2010, 38(9):  52-56,62.  doi:10.3969/j.issn.1000-565X.2010.09.010
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    In order to expose the causes of the poor bleachability and brightness stability of the sulfonated chemimachenical pulp（SCMP） from bamboo Bambusa chungii,NMR spectroscopy was used to analyze the structures of lignin samples of SCMP,bleached SCMP（BSCMP） and aged BSCMP.The results show that the SCMP of bamboo Bambusa chungii is of poor bleachability not only because the SCMP lignin has a high content of p-hydroxyl-phenyl unit,the phenolic hydroxyl groups of syringyl unit in the SCMP mainly exist in the form of ether bond,but also because there are 20 condensed units in per 100 aromatic units in the lignin.Moreover,it is found that,during the bleaching and the aging,the total contents of phenolic hydroxyl groups in lignin samples decrease by 30.7% and 38.4%,respectively,while those of carboxylic hydroxyl groups increase respectively by 53.2% and 55.3%,that Alk-O-Arand α-OAlk ether bonds in lignin samples are cleaved,while γ-OAlk ether bond is stable,and that the linkage of the side chain in lignin samples is simultaneously cleaved to form conjugated bonds such as Ar-CHO and Ar-COOH,thus reducing the brightness and the brightness stability of the pulp.

    Numerical Simulation of Dilution Water Applied to Headbox with Perforated Rolls
    Kang Guo-bing Chen Ke-fu Liu Jian-an Li Jun
    2010, 38(9):  57-62.  doi:10.3969/j.issn.1000-565X.2010.09.011
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    In order to determine whether dilution water can be used to adjust the weight deviation in cross direction when it is applied to the headbox with perforated rolls,the flow field in the headbox is numerically simulated with the CFD software Fluent.Then,the mixing of two kinds of liquid in the headbox is analyzed by using the Multiphase-Mixture model,and the effects of rotating zone on the flow field are discussed via the rotating reference frame（RRF） approach.Finally,the adjustment effect of dilution water at variable inlet speed and rotation speed of perforated rolls is evaluated.Simulated results show that the adjustment effect of dilution water is linear with the rotation speed of perforated rolls.Experimental results indicate that the addition of dilution water helps to decrease the deviation of the basic weight in cross direction by more than 3 points of percentage.The accordance between the experimental results and the simulated ones proves the applicability of dilution water in the headbox with perforated rolls.

    Nanocellulose Whiskers as Thickening Rheological Agent for Waterborne Polyurethane Dispersion
    Ye Dai-yong Zhou Liu-jia
    2010, 38(9):  63-67,74.  doi:10.3969/j.issn.1000-565X.2010.09.012
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    Nanocellulose whisker（NCW） suspension was prepared via the acid-catalyzed hydrolysis and the pro-duct was characterized.Then,the effects of temperature and NCW content on the viscosity of the suspension were analyzed,and the Ostwade power equation model of the suspension was discussed,finding that the viscosity of NCW suspension increases with the NCW content,but it is insensitive to temperature.Moreover,the effects of temperature and NCW content on the rheological properties of waterborne polyurethane（WPU） dispersion mixed with NCW suspension were investigated.The results show that the addition of NCW in the WPU dispersion helps to decrease the viscous flow activation energy and improve the thixotropy of the mixed system,meaning that NCW is an effective thickening agent of WPU dispersion.

    Synthesis and Addition Polymerization of Norbornene Derivative with a Functional Group of Pendent Azobenzene
    He Xiao-hui Shi Ling Nie Hua-rong Chen Yi-wang Yuan Bin Wu Qing
    2010, 38(9):  68-74.  doi:10.3969/j.issn.1000-565X.2010.09.013
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    Norbornene derivative with a functional group of pendent azobenzene was synthesized and the addition copolymerization and homopolymerization of the product were carried out using the catalytic system of bis-（β-keto-naphthylamino）nickel（II）/B（C6F5）3 in toluene.Then,the polar monomer and the polymers were characterized by means of IR,1H NMR,13C NMR,UV,GPC,TGA and DSC.The results show that the polar monomer and the polymers all exhibit broad optical absorption in the range from 300 to 400nm,that the relative molecular mass of the copolymer and the homopolymer are respectively 4.78×104 ～5.15×104 and 6.5×105～1.28×106,that the introduction of alkyl chain decreases the glass transition temperature of the polymers to less than 573K,that the polymers are of strong thermal stability and the thermal decomposition temperature is up to 593K,and that the solubility of the copolymer is better than that of the homopolymer.

    Synthesis and Characterization of 2,7-Dibromospiro[Fluorene-9,9′-（2′,7′-Dihydroxy-1′,8′-Disulfonic-Xanthene）]
    Wang Ling-yun Song Yuan-jie Cao De-rong
    2010, 38(9):  75-79.  doi:10.3969/j.issn.1000-565X.2010.09.014
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    First,2,7-dibromospiro[fluorene-9,9′-（2′,7′-dihydroxy-xanthene）]（Compound Ⅲ） was prepared through such three steps as Br2/Fe bromination,CrO3/Ac2O oxidation and resoreinol/ZnCl2 catalytic condensation,with fluorene as the starting material.Then,2,7-dibromospiro[fluorene-9,9′-（2′,7′-dihydroxy-1′,8′-disulfonic-xanthene）]（Compound Ⅳ） was synthesized via the sulfonation of Compound Ⅲ with concentrated sulfuric acid and was characterized by means of IR,1H NMR and UV-Vis,etc.Finally,the effects of reaction temperature,reactant molar ratio and reaction time on the sulfonation yield were investigated,and the optimal reaction conditions for Compound Ⅳwith a yield up to 86.5% were determined,that is,adding 1g of Compound Ⅲ together with 3mL concentrated sulfuric acid for the sulfonation at 70℃ for 2h.

    Materials Science & Technology
    Influences of S/Al of Cement and Sulfate in Extravasation Solution on Chloride Threshold Value
    Li Peng-ping Su Da-gen Wang Sheng-nian Fan Zhi-hong
    2010, 38(9):  80-84.  doi:10.3969/j.issn.1000-565X.2010.09.015
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    This paper deals with the influences of the S/Al molar ratio of cement and the sulfate in extravagation solution on the chloride threshold value via the linear polarization method,the mercury injection test and XRD.The results show that,with the increase of S/Al molar ratio,the chloride threshold value first increases and then decreases,while the chloride bounded in cement hydration products keeps reducing,that the S/Al molar ratio corresponding to the maximum chloride threshold value decreases with the increase of Al2O3 content of cement.More-over,it is also found that,when the specimens are immersed in the composite solution with the SO42- and Cl-concentrations similar to those of seawater,the chloride threshold value first increases and then decreases with the increase of S/Al molar ratio,but it is lower than that of the specimens immersed in NaCl solution,and that,with the penetration of the mortar first becomes denser and then presents a volume expansion due to an excessive penetration,thus resulting in the decrease in chloride threshold value.

    Oxidation Behaviors of Hot-Dipped Zn-Ni-V Alloy Coating
    Xu Qiao-yu Zhou Wei
    2010, 38(9):  85-89.  doi:10.3969/j.issn.1000-565X.2010.09.016
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    This paper deals with the isothermal oxidation behaviors of hot-dipped Zn and Zn-0.05%Ni-0.05%V coatings at 350℃.In the investigation,the surface and section morphologies as well as the phase composition of the coatings before and after the oxidation were analyzed by means of SEM,OM,EDS and XRD.The results show that Zn-0.05%Ni-0.05%V coating effectively restrains the Fe-Zn reaction and the extra-thickness growth of ζ phase,that both the Zn and the Zn-0.05%Ni-0.05%V coatings are composed of ZnO and FeZn8.87 after being oxidized at 350℃ for 150h,that the kinetic curves of isothermal oxidation of the coatings mainly obey the parabolic rate law,and that the Zn coating possesses large oxidation mass gain due to the massive holes in it,while the Zn-0.05%Ni-0.05%V coating is of strong oxidation resistance owing to the formation of dense microstructure.

    Dynamic Response of Laminated SiC/Al Composites Subjected to Ballistic Impact
    Chen Wei-ping He Zeng-xian Huang Dan Luo Jie
    2010, 38(9):  90-95,101.  doi:10.3969/j.issn.1000-565X.2010.09.017
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    Ballistic impact tests were made on laminated SiC/Al composites with two different structures.The results show that,as compared with Structure A possessing two layers of ceramic plate,Structure B possessing three layers of ceramic plates exhibits better structural integrity when it is subjected to ballistic impact,that the mass and length losses of the projectile impacting on Structure A are respectively 66.42% and 62.92%,while those on Structure B are respectively 63.65% and 65.43% that the single ceramic plate in Structure B is thinner than that in Structure A,but the abrasion of Structure B on the projectile is stronger than that of Structure A,and that,as a part of an integral structure of laminated ceramic/metal composite,metal lining plates absorb partial impact energy,thus Leading to the backward deformation and the resistance on the ceramic comminuting cone and the projectile.In addition,the heat produced at instantaneous projectile-target contact leads to partial corrosion on the projectile,which is one of the reasons for the mass and length losses of the projectile and for the partial melting on metal lining plate.

    Structure and Properties of Chitosan/Rectorite Nanocomposites
    Wang Xiao-ying Liu Bo Sun Run-cang Wu Jun
    2010, 38(9):  96-101.  doi:10.3969/j.issn.1000-565X.2010.09.018
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    Chitosan/rectorite nanocomposites with various rectorite contents were prepared via the solution intercalation method,and the thermal stability and antibacterial activity of the products were investigated.Then,the effects of rectorite content and interlayer distance on the properties of the products were analyzed.The results show that（1）chitosan chains insert into the rectorite layer and rectorite uniformly disperses in the chitosan matrix;（2） both the rectorite content and the interlayer distance greatly affect the properties of the nanocomposites;（3）the best intercalation effect can be achieved at a chitosan-to-rectorite mass ratio of 12∶1;（4）the nanocomposites are superior to chitosan in terms of antibacterial activity,with its minimum inhibition concentration and inhibition time for gram-positive bacteria espectively being 1/4～1/2 and 3～5 times that of chitosan;（5）the antibacterial activity of the nanocomposites,positive to the rectorite content and the interlayer distance,is better in restraining gram-positive bacteria than in restraining gram-negative bacteria;and（6）the thermal stability of the nanocomposites is stronger than that of chitosan.

    Gas-Sensing Properties of Novel Composite Film Doped with Carbon Nanotubes
    Lin Wei Huang Shi-zhen Chen Wen-zhe
    2010, 38(9):  102-107.  doi:10.3969/j.issn.1000-565X.2010.09.019
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    In this paper,first,SnO2/WO3/MWCNT composite thin film was prepared by magnetron sputtering a tin（Sn） target and a tungsten（W） target in a RF（Radio Frequency） reactive mode,and the corresponding gas sensor was fabricated.Next,the cross-section morphology,phase structure and chemical composition of the film were investigated by means of FSEM,XRD and XPS,respectively.Then,the gas-sensing properties of the gas sensor,such as the sensitivity,the selectivity and the response and recovery,were tested.The results of the experments show that the composite thin film gas sensor exhibits excellent gas-sensing,and that is sensitive to NO2 bat insensitve to other disturbance gases,and that elements W,Sn and C exist in SnO2/WO3/MWCNT composite thin film mainly in the form of W＋6,Sn＋4 and C,respectively.Finally,the mechanism of gas-sensing response of the film was primarily analyzed and discussed.

    Architecture & Civil Engineering
    Calculation and Analysis of Basic Snow Pressure in Liaoning Province
    Zhang Yan-nian Zhang Yong Wang Yuan-qing Shi Yong-jiu
    2010, 38(9):  108-112.  doi:10.3969/j.issn.1000-565X.2010.09.020
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    In this investigation,first,the snow load data of various cities in Liaoning is statistically analyzed accor-ding to the snow data provided by Liaoning Provincial Meteorological Bureau,and the basic snow pressure in Liaoning are calculated through the moment method and the Gumbel method,respectively.Then,the distribution function is tested according to the Kolmogorov criterion.Finally,the calculated results are compared with the values re-commended by current design codes and with the results presented in the correlative literature.It is found that,in most cases,the basic snow pressure calculated by the Gumbel method is more accurate than that by the moment method,that the basic snow pressure in some areas recommended by current codes is too low,so that it should be increased in the next revision of the codes,and that the basic snow pressure in heavy snowstorm areas and on snow-load-sensitive structures should be multiplied by an amplification factor before the next revision of the codes.

    Comprehensive Benefit Economy Model in Full Life Cycle of Water-Saving Projects for Green Building
    Chai Hong-xiang Hu Xue-bin Peng Shu-juan
    2010, 38(9):  113-117.  doi:10.3969/j.issn.1000-565X.2010.09.021
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    By systematically analyzing the factors that influence the comprehensive benefit in the full life cycle of water-saving projects for green building,a comprehensive benefit economy model including the direct water-saving benefit,the environmental and social benefit as well as the incremental cost in the full life cycle is constructed,with the net present value as the evaluation and measurement index of comprehensive benefit.Then,the model is simulated and applied to a water-saving demonstration project for green building in West China to verify its rationality and practicality.Simulated results indicate that,in the full life cycle,the comprehensive benefit,the incremental cost and the benefit-to-cost ratio of the project reach 39.3 million yuan,9.3 million yuan and 4.2∶1,respectively,meaning that the water-saving project is of remarkable comprehensive benefit.

    Strand Tension in Anchor-Span Suspension Bridge at Different Temperatures
    Tan Hong-mei Xiao Ru-cheng
    2010, 38(9):  118-122.  doi:10.3969/j.issn.1000-565X.2010.09.022
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    Two methods,one is based on the simplified expression and the other is on the calculation program,are proposed to reveal the influence of temperature on the strand tensions in the anchor span and each side span of suspension bridge,with Zhujiang Huangpu Bridge in Guangzhou as an example.It is found that the calculated results obtained from the two methods are approximate to each other,that temperature variation has a greater influence on the tension in anchor span than on that in side span when the saddles are fixed,that the influence coefficient of temperature in side span and anchor span are respectively about-1kN/℃ and-6～-7kN/℃,that the force difference between side span and anchor span may go beyond the maximum friction when the temperature change exceeds the ideal range,so that some countermeasures should be taken to avoid the strand sliding during the construction,and that the influence coefficient of temperature in anchor span is very small when the saddles are free.

    Simulation Method of Step-by-Step Construction of Long-Span Steel Structures
    Pan Duo-zhong Wei De-min
    2010, 38(9):  123-126,137.  doi:10.3969/j.issn.1000-565X.2010.09.023
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    One of the difficulties in mechanical analysis of construction process is the time variable of structure geo-metry and boundary conditions.In this investigation,first,based on the engineering practice that a pre-angle can be set between pre-erected and after-erected substructures via an inter-node design,a new construction simulation method is proposed.In this method,live and dead substructures are solved sequentially,and the rotational constraint on boundary nodes of dead substructures can be adjusted.Then,for the system with statically-determined or super-determined dead substructures,two methods to adjust the boundary rotational condition are presented,and the finite element formulas of live and dead substructures are respectively derived.Finally,the proposed method is used to analyze and simulate some typical cases.The results indicate that,by using the proposed method,the after-erected substructures deform more slightily and can be facilitated more easily.As a result,the final geometry is closer to the design shape.

    Biological Engineering
    Chromatography Separation and Structure Identification of Enzymatically-Synthesized Naringin Palmitate
    Huang Jian-rong Li Bing Zhang Xia Li Lin
    2010, 38(9):  127-131.  doi:10.3969/j.issn.1000-565X.2010.09.024
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    First,preparative high-pressure liquid chromatography was used to isolate and purify the naringin palmitate enzymatically synthesized by immobilized lipase Novozym 435 in the t-amyl alcohol system.Next,IR spectrum,mass spectrum and 13C NMR were used to identify the purified product,and the mechanism of regioselectivity of the reaction was discussed.Then,the feasible operation conditions were determined as follows： a C18 column（21.5mm×250.00mm,10μm） with methanol as the mobile phase at a flowrate of 20mL/min,an injection volume of 3mL with the concentration of 30mg/mL.In these conditions,the product with a purity of more than 99% was obtained.Finally,the purified product was identified as monoester of naringin and palmitic acid,and the regioselective acylation was found preferring the 6″-hydroxyl group of naringin glucose.

    Preparation and Asymmetric Inactivation of Protoplasts from Aspergillus
    Xu De-feng Zhao Hai-feng Zhao Mou-ming
    2010, 38(9):  132-137.  doi:10.3969/j.issn.1000-565X.2010.09.025
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    In order to improve the quantity and viability of protoplasts released from the mycelia of Aspergillus oryzae HN3042 and Aspergillus niger CICC2377,the effects of carbon resources,mycelia age,osmotic stabilizers,enzyme concentration,incubation time and regeneration media on the release and regeneration of protoplasts were investigated,and the parameters of asymmetric inactivation for the protoplasts were analyzed.Afterwards,suitable conditions for protoplast release were determined.The results indicate that,with MPY consisting of maltose,polytephone and yeast extract as the submerged medium,0.7mol/L NaCl combined with 0.4mol/L sorbitol as the osmo-tic stablizer,and with hypertonic soybean-extract solid medium as the regeneration medium,the released protoplasts show a regeneration efficiency of above 30%.Moreover,according to the asymmetric inactivation curves,it is found that both Aspergillus oryzae HN3042 and Aspergillus niger CICC2377 protoplasts are in critical inactivation stage when they are respectively under the irradiation of 15W ultraviolet from 13cm vertically away for 15min or in a 65℃ water bath for 10min.

    Directed Evolution of Douchi Fibrinolytic Enzyme
    Zhang Shao-ping Cui Tang-bing Chen Liang Guo Yong
    2010, 38(9):  138-141,146.  doi:10.3969/j.issn.1000-565X.2010.09.026
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    In order to improve the medical value of Douchi fibrinolytic enzyme（DFE）,random mutagenesis on DFE gene of Bacillus subtilis DC-12 was performed by using the error-prone PCR strategy to construct a mutant library.After three cycles of error-prone PCR and a screening using substrate H-D-Val-Leu-Lys-pNA,the best mutant enzyme mDFE3 with improved catalytic efficiency was obtained.Gene sequence analysis of mDFE3 shows that the mutant is of six nucleotide substitutions,four of which cause amino acid substitution and the other two cause synonymous mutation.According to the three-dimension structure of mDFE3 mimicked by swiss-model repository,three mutated amino acids are found to locate in loop structures and one is in α-helix.Moreover,the enzyme kine-tic analysis indicates that the Km value of mDFE3 decreases from 0.58mol/L to 0.45mmol/L and that the catalytic efficiency（kcat） of mDFE3 is 2.57 times that of DFE.

    Detection of Viable Bacterium Cells Based on Propidium Monoazide in Combination with PCR
    Luo Jian-fei Lin Wei-tie Guo Yong
    2010, 38(9):  142-146.  doi:10.3969/j.issn.1000-565X.2010.09.027
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    PCR-based molecular biotechnologies are ineffective in discriminating dead cells from viable ones,which may result in inaccurate estimation of cell number.In order to solve this problem,propidium monoazide（PMA） treatment was used as a pretreatment for the genome extraction of environmental samples,in which PMA covalently crosslinks with DNA molecules in dead cells and inhibits the PCR amplification of DNA molecules.The results indicate that the PCR amplification of DNA from heat-killed E.coli cells can be inhibited by PMA with a mass concentration of 3μg/mL after an exposure for more than 3min,while the PCR amplification of DNA from viable cells is slightly inhibited by PMA with a mass concentration of more than 50μg/mL,and that PMA treatment is effective when the turbidity is less than 10 NTU and is ineffective when the turbidity is greater than 100NTU.

    Contents of Stilbene Glycoside in Root and Stem Callus of Polygonum multiflorum Thunb
    Shao Li Cui Tang-bing Zhao Shu-jin
    2010, 38(9):  147-150.  doi:10.3969/j.issn.1000-565X.2010.09.028
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    In order to obtain the suspension cell line of Polygonum multiflorum Thunb.and investigate the suspension culture and stilbene glycoside metabolic pathways,callus must be obtained.In this paper,the root and the stem of Polygonum multiflorum Thunb.were used as explants to acquire the most suitable callus induction medium via orthogonal tests.It is found that the root and the stem are most appropriately induced on the MS medium containing 1mg/L 2,4-dichlorophenoxyacetic acid and 0.4mg/L naphthaleneacetic acid at 26℃ in dark,with the induction rate being up to 96.7%.Moreover,HPLC results indicate that the contents of stilbene glycoside in root and stem callus are respectively 1.5 and 0.4mg/g.

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