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    25 December 2010, Volume 38 Issue 12
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    Mechanical Engineering
    Bending-Torsion Coupling Design of Spar Cap of Compliant Wind Turbine Blade
    Liu Wang-yu Zhang Yong
    2010, 38(12):  1-6.  doi:10.3969/j.issn.1000-565X.2010.12.001
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    This paper deals with the bending-torsion coupling design of the spar cap of 1.5MW wind turbine blade by using biased hybrid fibers.The corresponding control parameters are set,and the effects of both the angle and the volume fraction of off-axis carbon fibers on the bending-torsion coupling parameters are analyzed.Theoretical results indicate that the bending-torsion coupling effect is only related to the laminated materials.Simulated results show that（1） either the biased hybrid spar cap or the skin helps to achieve efficient bending-torsion coupling,with the corresponding optimal angles respectively being about 20.0° and 13.0°;and（2）,under the constraints of fiber tensile and compressive strain,interlaminar shear stress and Von Mises stress on layers,the spar cap is of the most excellent sta-tic performance at a volume fraction of off-axis carbon fibers of 45% and an angle of off-axis carbon fibers of 20°.

    Multi-Objective Optimization of Forming Process of Sheet Metal Based on Springback Control
    Yang Xiang-an Ruan Feng Zhou Chi
    2010, 38(12):  7-13.  doi:10.3969/j.issn.1000-565X.2010.12.002
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    In order to control the springback in the forming process of sheet metal,a synthetical method to evaluate the springback is proposed based on multi-objective opitmization.In this method,two objective functions are established,one of which considers both the equivalent stress deviation and the coordinates of Gaussain integration point,and the other considers the equivalent plastic strain.Then,an integrated optimization model based on the springback control is put forward by combining the design of experiment,the response surface method and the multi-objective genetic algorithm with LS-DYNA keyword file.Moreover,the influences of variable blank holder force（VBHF） and drawbead restraining force on the springback are analyzed.The results show that（1） when the VBHF takes its value first small and then great,large plastic deformation can be achieved,and larger blank holder force in the later stage may lead to small equivalent stress deviation in the thickness direction,thus significantly inhibiting the springback;（2） a reasonable configuration of drawbeads adapting to the product shape and appropriate drawbead restraining forces also have some effects on the springback reduction;and（3） the amount of springback decreases from 1.95250mm to 0.67451mm after the optimization,which means that the proposed multi-objective functions are effective in evaluating the springback.

    Composite Machining of Copper Tube with Micro Straight Grooves via Oil-Filled Spinning and Multi-Pass Drawing
    Ou Dong-sheng Tang Yong Wan Zhen-ping Lu Long-sheng Lian Bin
    2010, 38(12):  14-19.  doi:10.3969/j.issn.1000-565X.2010.12.003
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    High-quality copper tube with micro straight grooves,which is less than 6mm in outer diameter,was fabricated via the composite process of high-speed oil-filled spinning and multi-pass drawing.Then,the corresponding machining mechanism was analyzed,and the influences of machining parameters on the quality of the product were investigated.The results indicate that,during the machining,excessive drawing reduction may result in groove folding and crack,and excessive roundness error may lead to crinkle even depression;and that,when the entry cone angle of the drawing die is 16°,the length of sizing region is 4mm and the exit cone angle of the drawing die is 30°,high-quality copper tube with micro straight grooves can be machined under good lubrication condition and small residual stress.Moreover,it is found that stable-quality copper tube with micro straight grooves,which is less than 6mm in outer diameter,can be machined by controlling the drawing parameters and the roundness error.The inner grooves of the product tend to close,just like a dovetail,which benefits the improvement of capillary force of the tube.

    Identification of Welding Seam Offset Based on PCA_RVM
    Du Jian-hui Shi Yong-hua Wang Guo-rong Huang Guo-xing
    2010, 38(12):  20-23.  doi:10.3969/j.issn.1000-565X.2010.12.004
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    In order to improve the precision of the seam-tracking system based on rotating arc sensor,an identification method of welding seam integrating the principal component analysis（PCA） and the relevance vector machine（RVM） is proposed,marked as PCA_RVM.In this method,first,the welding current signals are processed by using a wavelet filter,followed by the cycle partition and data normalization.Then,the data set of acquired welding seam offset is analyzed via PCA and is projected in low-dimension PCA space,and the low-dimension data set is used as the training data set of RVM.The proposed method is tested by some experiments.The results show that（1） the maximum error and mean error of PCA_RVM are respectively 0.54mm and 0.43mm;（2） the precision of PCA_RVM,which is better than those of the methods based on interval integral,neural network and support vector machine,is as high as RVM;and（3） the runtime of PCA_RVM is more than that of the method based on interval integral but is less than those of the methods based on neural network,support vector machine and RVM.It is thus concluded that PCA_RVM is more suitable for the seam-tracking system based on the rotating arc sensor.

    Warm Flow Compaction Behaviors of Iron-Based Powders
    Gao Hong-yun Shao Ming Qu Sheng-guan Xiao Zhi-yu
    2010, 38(12):  24-28.  doi:10.3969/j.issn.1000-565X.2010.12.005
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    In order to explore the effect of warm flow compaction on the forming process of iron-based powders,the behaviors of warm flow compaction of the mixture of atomized iron powders and fine ferrocarbonyl powders are analyzed by using a self-developed testing system.By comparing the room-temperature compaction with the warm flow compaction,it is found that the decrease rate of lateral pressure in the warm flow compaction with the increase of transverse distance is slow,especially,at general powder-forming pressure of 600～700MPa,warm flow compaction is of higher lateral pressure coefficient than room-temperature compaction.This means that,in the same position in a part,warm flow compaction yields higher lateral pressure and relative density.It is also found that,for polyethylene glycol（PEG） binder,the optimal compaction temperature and speed are respectively 62℃ and 240mm/min,and the suitable PEG content ranges from 2% to 3%;and that,during the warm flow compaction,binder sufficiently coats and bonds metal powders,thus improving the filling capability of powders and the supportability of binder lubrication film.As a result,the pressure transmission effect among powders becomes better,and powder metallurgy part with complicated shape and high relative density can be successfully obtained.

    TII Protocol M odeling and Analysis Based on Colored Petri Network
    Zhou Yue-bin Liu Gui-·xiong
    2010, 38(12):  29-34.  doi:10.3969/j.issn.1000-565X.2010.12.006
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    For TII(Transducer Independent Interface)protocol，there are different application methods and implementations，which need to be modeled，analyzed and verified．In this paper，first，according to diferent channel types，a hierarchical CPN(Colored Petri Net)model of TII protocol is established．Then，by using the average delay of data transmission，the channel utilization，the data transfer rate and the loss rate of data frames as performance evaluation indexes，the performances of the model are analyzed with the help of CPN Tools．Moreover，the performance indexes，which are affected by such interface parameters as interface rate，sampling rate ratio，sampling data length and buffer queue length，are discussed，and several methods and measures are proposed to improve model perform ances，such as increasing the channel data length and adopting controllable continuous sampling，virtual multi—channel，last—in—first·out buffer and first—in—first—out packet loss．Application results of the proposed model show that，when STIM channel is BDS(Buffered Data Sequence)，the lOSS rate of data frames，the data transfer rate and the average delay of data transmission are 0，1 500 B／s and 0．21 ms，respectively．

    Inspection Algorithm of Solder Joints Based on Weighted Bidirectional 2D Linear Discrimination Features
    Kuang Yong-cong Xie Hong-wei Ouyang Gao-fei Zhang Xian-min
    2010, 38(12):  35-40.  doi:10.3969/j.issn.1000-565X.2010.12.007
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    In order to overcome the disadvantages of the existing automatic optical inspection（AOI） algorithm for solder joints,a new inspection algorithm based on weighted bidirectional 2D linear discrimination analysis is proposed,which takes into account the characteristics of AOI and improves the conventional bidirectional 2D linear discrimination analysis by weighting different classes and samples during the calculation of covariance matrix.By this algorithm,more discriminative features can be extracted.The improved algorithm is then applied to the solder joint inspection to automatically classify the solders from different batches.Experimental results show that,as compared with the commonly-used algorithm based on image comparison or image analysis,the proposed algorithm significantly reduces the misdiagnosis rate with the detection speed meeting the practical demands well.

    Rapid Prototyping of Nickel Metal Products via Jet Electrodeposition
    Tian Zong-jun Wang Gui-feng Huang Yin-hui Liu Zhi-dong Shen Li-da Gao Xue-song
    2010, 38(12):  41-44,55.  doi:10.3969/j.issn.1000-565X.2010.12.008
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    By combining the template technology,the friction technology and the numerically-controlled jet electrodeposition,a novel technology named frictional jet electrodeposition is developed to manufacture special-typed nickel metal products based on the principle of rapid prototyping.Experimental results show that（1） the template technology helps to improve the machining accuracy of jet electrodeposition and directly manufacture special-typed pro-ducts with complicated structure;（2） the polishing and impacting of hard particles effectively prevent the products form impurities adsorption and remove burrs and nodules;and（3） the developed technology integrates the advantages of jet electrodeposition and rapid prototyping,so that it effectively reduces equipment complexity and production cost and helps to manufacture metal parts with complicated shape,dense structure and smooth surface in a direct and rapid manner.

    Electronics, Communication & Automation Technology
    Recognition of Unconstrained Handwritten Offline Chinese Text Line Based on Multiple Information Fusion
    Li Nan-xi Jin Lian-wen
    2010, 38(12):  45-49.  doi:10.3969/j.issn.1000-565X.2010.12.009
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    The recognition of unconstrained handwritten offline Chinese text line is a difficult problem in current character recognition domain.In order to reduce the interferences from negative samples during text line recognition,a probabilistic model is developed.In this model,negative samples are treated as an information source and are integrated with other kinds of information such as the recognition information of isolated characters and the geometric information of text line.By using only two classifiers,the proposed probabilistic model can be successfully implemented.Experimental results on a real multiple-writer handwritten text database show that,by using the proposed method,the correct recognition rates reach 61.29% without any language model and 72.73% with a bi-gram language model,respectively,which means that the method is effective.

    Method for Selecting Control Points for Remote Sensing Image Registration Based on Distribution Quality
    Guo Yan Gu Yan-feng Guan Zhuo-wei Zhang Ye
    2010, 38(12):  50-55.  doi:10.3969/j.issn.1000-565X.2010.12.010
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    In order to improve the registration accuracy of remote sensing image,a method for selecting control points is proposed based on uniform distribution quality.In this method,first,control points are extracted via the scale-invariant feature transform,and wrong matched control points are deleted by means of random sample consensus（RANSAC）.Then,the common area of the image pair is divided into several sub-regions and suitable control points are selected according to the distribution quality.Finally,the parameters of the affine transformation model are estimated through the least squares approximation and the registration is conducted via the coordinate transformation of the input image.Experimental results of various kinds of remote sensing images prove that the proposed method effectively removes the wrong matched control points,guarantees the distribution uniformity of control points and reduces the registration error.

    Ultra-Wideband Slot Antenna with Controllable Notched Bandwidth
    Li Chun-mao Zhang Bo
    2010, 38(12):  56-60.  doi:10.3969/j.issn.1000-565X.2010.12.011
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    As the notched bandwidth of the existing band-notched ultra-wideband（UWB） antennas are difficult to control,this paper presents a novel kind of UWB slot antenna with controllable notched bandwidth.In the investigation,first,a broadened rectangular solt antenna is used to generate ultra-wideband characteristics covering 3.1～10.6GHz band.Then,a pair of inverted L-shaped slits is embedded in the ground to create a band-notched function.The notched bandwidth can be easily controlled by adjusting the width and location of the slits.Finally,an UWB antenna with rejection band at 5.0～6.0GHz is successfully designed and fabricated,which effectively eliminates the potential interference from WLAN.

    Non-Cooperative Program Game Model for Capacity Analysis of Mobile Ad hoc Networks
    Yang Juan Yang Dan Zhao Hong Ge Yong-xin
    2010, 38(12):  61-66,72.  doi:10.3969/j.issn.1000-565X.2010.12.012
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    Capacity is one of the key properties for the QoS（Quality of Service） support in Mobile Ad hoc Networks（MANET）.In this paper,based on the characteristics of wireless channel and link throughput in MANET,a strategy space for node flow distribution and a flow utility function based on network flow rate and delay are constructed based on the network flow theory,the coloring theory and the non-cooperative program game theory.Then,a capacity analysis model of MANET is proposed based on shared channel in a normalized time slot,and the exis-tence of its Nash equilibrium solution is proved,followed by the presentation of an idiographic form.Numerical simulation indicates that the proposed model is universal and is effective in analyzing the MANET capacity.

    Geographic Opportunistic Routing with Optimized Lifetime for Sensor Networks
    Yue Lin Yi Ben-shun Xiao Jin-sheng Fang Yan-jun
    2010, 38(12):  67-72.  doi:10.3969/j.issn.1000-565X.2010.12.013
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    In order to improve the lifetime of wireless sensor networks,a geographic opportunistic routing protocol with optimized lifetime marked as GOROL is proposed,and a residual energy and forwarding efficiency model is established according to the characteristics of GOROL.Then,an adaptive forwarder-set optimization algorithm is put forward based on the model,which takes into consideration both the residual energy and the forwarding efficiency to ensure the transmission efficiency and maximize the lifetime.Simulated results show that,as compared with the energy-aware routings such as CORP and GOR,GOROL is of longer lifetime in the network.

    Initial Alignment for Integrated Navigation System Based on Neural Network and Wavelet
    Zhang Tao Xu Xiao-su
    2010, 38(12):  73-78,89.  doi:10.3969/j.issn.1000-565X.2010.12.014
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    In order to avoid the system accuracy degradation in the initial alignment due to the GPS outage in SINS/GPS/MCP integrated navigation system,a scheme based on neural network and wavelet is proposed,in which the relevant characteristic components denoised by wavelet are treated as the training samples of neural network.Then,a filtering model based the scheme is established,which consists of the equations of misalignment angle,velocity error and position error in SINS system,as well as the state and measurement equations of Kalman filter with velocity and heading matching.Moreover,in order to verify the proposed scheme,simulations are carried out in the conditions of GPS outage,neural network introduction and wavelet denoising.The results indicate that the introduction of neural network avoids the velocity accuracy degradation,and that the retraining of neural network using wavelet denoising effectively improves all the indexes of SINS/GPS/MCP system.It is thus concluded that,as the adoption of wavelet denoising can improve the approximation of neural network to the actual model,the alignment accuracy is further improved.

    Multiple Neural Network-Based Model to Predict Ammonia Nitrogen Content in Wastewater
    Yu Wei Luo Fei Yang Hong Xu Yu-ge
    2010, 38(12):  79-83.  doi:10.3969/j.issn.1000-565X.2010.12.015
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    In order to overcome the nonlinearity and large time delay in the biochemical process of wastewater,this paper proposes a prediction model of effluent quality based on the multiple neural network.In this model,the input space is divided into several subspaces via the subtractive clustering,and the corresponding submodels are established based on neural network in the subspaces.Then,in order to eliminate the severe correlation among the submodels and to improve the accuracy and robustness of the model,the submodels are combined via the principal component regression（PCR）.Moreover,the prediction accuracy of the high measured value is improved by using a modified objective function and the generalization ability of the model is strengthened via the weighted feedback correction.Finally,the proposed method is applied to the prediction of ammonia nitrogen content of the effluent from a wastewater treatment plant,and the results verify the effectiveness of the proposed method.

    Hierarchical Identity-Based Signature Scheme with Short Public Parameters
    Yang Yang Hu Yu-pu Zhang Le-you Liu Zhen-hua
    2010, 38(12):  84-89.  doi:10.3969/j.issn.1000-565X.2010.12.016
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    As the existing hierarchical identity-based signature schemes are not practicable in the real world due to the excessive length of public parameters,a description of hierarchical identity-based signature scheme is presented,and a security model is established.Then,a novel hierarchical identity-based signature scheme is proposed,with its security being proved based on the computational Diffie-Hellman assumption in the established security model.The results indicate that,as compared with the existing hierarchical identity-based signature schemes,the proposed scheme possesses shorter public parameters and requires less bilinear pairing operation for verification.

    Food Science & Technology
    Effects of Crosslinking and Acetylation Modification on Properties of Sweet Potato Starch
    Gao Qun-yu Wang Kai Wu Lei
    2010, 38(12):  90-94,99.  doi:10.3969/j.issn.1000-565X.2010.12.017
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    In order to reveal the influences of crosslinking and acetylation modification on the properties of starches,the paste properties of crosslinked and/or acetylated sweet potato starch were investigated,and the morphological and structural changes of the modified starches were observed and analyzed by means of SEM,FT-IR and XRD.The results indicate that（1） after the crosslinking,the hot paste stability of the paste improves but the transparency decreases,and the freeze-thaw stability shows no obvious improvement;（2） the acetylated starch is of lower gelatinization temperature,better paste transparency and freeze-thaw stability,and poor hot paste stability;and（3） the dual modification by crosslinking and acetylation decreases the gelatinization temperature of sweet potato starch,improves the hot paste stability,paste transparency and freeze-thaw stability.

    Effect of Xanthan Gum on Properties of Tapioca Starch Paste
    Luo Zhi-gang Wang Ying Luo Fa-xing
    2010, 38(12):  95-99.  doi:10.3969/j.issn.1000-565X.2010.12.018
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    In order to reveal the synergy principle between polysaccharide gum and starch,the effects of xanthan gum（XG） on the properties of tapioca starch（TS） paste were investigated by using a Bradender viscometer,a scanning electron microscope and a Haake rheometer.The results indicate that（1） the addition of xanthan gum increases the peak,breakdown and final viscosities of native TS,but decreases the gelatinization temperature and the setback value;（2） xanthan gum effectively reduces the syneresis,but may result in larger ice crystals in the starch gel;and（3） the addition of xanthan gum increases the storage modulus,and obviously decreases the loss tangent at an angular frequency of more than 0.5rad/s,which makes the starch-xanthan paste behave more solid-like charac-teristics than the native starch paste.

    Preparation of Starch-Based Adsorption Material via Enzymolysis and Heated-Ethanol Co-Processing
    Zhao Yong-qing Zhang Ben-shan Chen Fu-quan
    2010, 38(12):  100-104.  doi:10.3969/j.issn.1000-565X.2010.12.019
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    A novel starch-based absorption material was prepared via enzymolysis and heated-ethanol co-processing,with corn starch as the material.The specific surface area,morphology of the product were then characterized by using a pore surface area analyzer and a scanning electron microscope,and the capabilities of water absorption and oil absorption of the product were investigated.The results show that,after the co-processing,many holes form in starch granules,and the granules become loose,with increases in the specific surface area,the hole diameter and the hole volume.Moreover,it is indicated that the starch granules after the co-processing are of excellent absorption property.For example,at an enzyme dosage of 0.9%,its water absorption and oil absorption are respectively 5.1 and 1.9 times those of the native corn starch.

    Coupled Regeneration of Decolourization and Decalcification Resin in Sugar Industry and Reuse of Regenerated Waste Liquid
    Zhu Si-ming Fu Xiong Yu Shu-juan Zhu Liang
    2010, 38(12):  105-109,119.  doi:10.3969/j.issn.1000-565X.2010.12.020
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    The treatment of regenerated waste liquid is a key to the application of ion exchange resin to the purification of sugar juice.In order to reuse the regenerated waste liquid,the regeneration of decolourization and decalcification resin in sugar industry was coupled by regenerating the decalcification resin using the waste liquid from regenerated decolourization resin,and the antioxidant activity and functional components of the coupled regeneration waste liquid were determined.The results indicate that（1） the complexation of Ca 2＋ with pigment benefits the Ca 2＋ desorption from the resin;（2） by regenerating 60mL of decalcification resin BK001 with 300mL of alkaline waste liquid in a regenerating procedure of decolourization resin（D201×7）,56.7g of calcium-rich pigment with antioxidant activity can be obtained,with a regeneration percentage of decalcification resin of 95.4%;（3） the contents of Na＋,Ca 2＋ and amino acids in the calcium-rich pigment are respectively 260.00,29.29 and 29.80mg/g;and（4） the absorbance of the aqueous pigment solution without NaCl meets the caramel standard presented by GB 8817—2001.

    Scavenging of In Vitro Hydroxyl Free Radical Using Feruloyl-Arabinose
    Lin Qi-ling Wen Qi-biao Ou Shi-yi Wu Lei-yan Lai Fu-rao
    2010, 38(12):  110-114.  doi:10.3969/j.issn.1000-565X.2010.12.021
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    Feruloylated oligosaccharides（FOs） were prepared by the hydrolysis of maize bran in dilute hydrochloric acid,and the component F-Ara was obtained by means of D301 macroporous resin chromatography and poly-amide resin purification from FOs.Then,the purity and structure of F-Ara were analyzed,and the capability of F-Ara for ·OH scavenging in vitro was compared with that of ferulic acid（FA）.The results show that（1） the purity of F-Ara approaches HPLC-purity level after the two above-mentioned resin separation processes;（2） at low concentration（2～6mmol/L）,F-Ara is similar to FA in terms of ·OH scavenging in vitro,while at high concentration（6～10mmol/L）,it is more efficient than FA;and（3） at the concentration of 10 mmol/L,the percentage of scavenging ·OH by F-Ara reaches 72.9%,while that of FA is only 62.4%.Thus,it is concluded that F-Ara is a natural and efficient free radical scavenger.

    Diffusivity of Solutes in Freezing Process of Gelatin Model Immerged in Quaternary Refrigerant Liquids
    Zeng Qing-xiao Ni Ming-long Zhu Zhi-wei Chen Bin Han Guang-he
    2010, 38(12):  115-119.  doi:10.3969/j.issn.1000-565X.2010.12.022
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    In order to reveal the diffusivity of solutes from the solution of quaternary refrigerant liquid to food in freezing process,the freezing process of gelatin in different conditions was investigated,and the influences of such immersion chilling and freezing variables as temperature,freezing time and total concentration on the absorption of NaCl,ethanol,propylene glycol and the total absorption were analyzed on a gelatin cylinder model.Moreover,the density and dynamic viscosity of the refrigerant liquid were measured.The results indicate that（1） the absorption of NaCl,ethanol and propylene glycol as well as the total absorption remarkably improves;（2） the diffusivity of the solutes decreases at low initial temperature;（3） high solution concentration may result in higher total absorption;and（4） in the freezing conditions of-40～-20℃ in this work,the total absorption is found to be only 2.70～6.23mg/g after 25min.

    Association State in Ethanol-Water Solution with Different Ethanol Concentration
    Zeng Xin-an Yang Xing
    2010, 38(12):  120-123.  doi:10.3969/j.issn.1000-565X.2010.12.023
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    This paper deals with the interaction between hydrogen bond association and ethanol content in ethanol-water solution by means of 1 NMR.The results show that（1）the weak hydrogen bond CH…O slightly changes with ethanol concentration;（2）CH2 is easier to form weak hydrogen bond and is more sensitive to ethanol concentration than—CH3;and（3） as for the strong hydrogen bond OH…O,OH groups in ethanol molecule are more sensitive to the concentration than water,and the strongest hydrogen bond association occurs at a mole fraction of ethanol（x） of 0.550.Furthermore,according to the association strength of hydrogen bond,the ethanol concentration can be approximately divided into three regions,namely,0x0.236,0.236≤x≤0.735 and 0.735x1.000.In the first region,there is a leading association in water molecule,while in the third region,there is a leading association in ethanol molecule,and,in the second region,the strongest and the widest hydrogen bond association net is formed by the interaction of ethanol and water molecules.

    Kinetic Model and Mechanism of Ultrasonic-Enhanced Subcritical CO_2 Extraction
    Qiu Tai-qiu Li Chao Tan Wei Yang Ri-fu Huang Xing-xin Fan Xiao-dan
    2010, 38(12):  124-128.  doi:10.3969/j.issn.1000-565X.2010.12.024
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    In order to reveal the enhancement mechanism of subcritical CO2 extraction by ultrasonic and describe the mass transfer enhanced with ultrasonic,some experiments were carried out and the data were fitted with the help of a kinetic extraction model.Then,the cavitations threshold at variable temperature and pressure were obtained based on theoretical calculation.Moreover,the cativation in the subcriticalCO2 extraction enhanced by ultrasonic was investigated according to the results of the experiments.The results show that（1） the established kinetic model fits the extraction data well;（2） the difference in E∞ and k values between the extractions with and without ultrasonic enhancement also confirm the obvious enhancement effect of ultrasonic for the mass transfer in subcritical CO2 extraction;（3） the occurrence of ultrasonic cavitation is rather easy at relatively high temperature and low pressure;（4） the cavitation occurs even under the conditions that cavitation is theoretically unavailable,for which there is no reasonable explanation;and（5） the enhancement is mainly due to the cavitation effect and the enhanced mass transfer.

    Biological Engineering
    Mechanism of Enzyme Activity Variation of Catalase with Ultrasonic Treatment
    Li Bing Wang Wen-zong Lin Hong-jia Chen Ling Li Lin
    2010, 38(12):  129-134.  doi:10.3969/j.issn.1000-565X.2010.12.025
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    In order to reveal the influencing mechanism of ultrasonic on the antioxidation defense system of microorganisms,catalase（CAT） was treated with ultrasonic and the effects of ultrasonic parameters on the enzyme activity of CAT were studied.Moreover,the secondary structure of CAT with and without ultrasonic treatment were analyzed by means of FT-IR.The results show that（1） the enzyme activity of CAT decreases with the increase in ultrasonic power;（2）the prolonging of irradiation time has no obvious effect on the enzyme activity of CAT;（3） the stable temperature and pH value for CAT treated with ultrasonic are respectively 37℃ and 7.4;and（4） after ultrasonic treatment,the kinetic parameters Km and Vmax of CAT both increase,and the secondary structure transfers from an ordered structure to a disordered one.

    Enzymatic Properties of Polyphenol Oxidase in Jerusalem artichoke
    Zhong Zhen-sheng Pan Xiao-qin Fang Ying-tong
    2010, 38(12):  135-139.  doi:10.3969/j.issn.1000-565X.2010.12.026
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    In order to reveal the oxidation-induced browning mechanism of the extracts from Jerusalem artichoke,the basic enzymatic properties of polyphenol oxidase（PPO） in Jerusalem artichoke were investigated by using a spectrophometer,with catechol as the substrate.In the investigation,the kinetics of enzymatic browning was investigated,and the effects of pH value,temperature,substrate concentration and enzyme concentration on the browning,as well as the effects of different substrates on the emzyme activity,were analyzed.The results show that（1） the optimal pH value and temperature for the enzymatic oxidation are respectively 4.8 and 35℃;（2） the PPO in Jerusalem artichoke is of poor thermal stability,with most of it deactivating after being heated at 85℃ for 5min;（3） the enzymatic browning accords with the Michaelis equation,and the kinetic parameters Km and Vmax are respectively 0.013mol/L and 7.5mmol/s;（4） the activity of PPO first greatly and then slightly increases with the enzyme concentration,with 0.8mL as the critical PPO dosage;and（5） the PPO in Jerusalem artichoke only affects o-polyphenol.

    Fermentative Production of Ethanol Affected by Deleting Lactate Dehydrogenase from Thermoanaerobacterium aotearoense
    Cai You-hua Lai Chao-feng Liang Ze-xin Li Ping Wang Ju-fang Zhu Ming-jun Liang Shi-zhong
    2010, 38(12):  140-144.  doi:10.3969/j.issn.1000-565X.2010.12.027
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    In order to improve the yield of ethanol,the lactate dehydrogenase in a key branch of Thermoanaerobacterium aotearoense was deleted via the homologous recombination,and the thermophilic and anaerobic metabolic engineered Thermoanaerobacterium aotearoense,namely Δldh mutant was screened.Then,glucose fermentation,xylose fermentation and glucose/xylose co-fermentation of Δldh mutant and the wild strain were respectively performed to produce ethanol.The results indicate that（1） as compared with the wild strain,Δldh mutant is of higher ethanol yield and rapid suger consumption;（2） both the Δldh mutant and the wild strain grow well on glucose and xylose;（3） as compared with sole xylose fermentation,a xylose restraining may occur during the glucose/xylose co-fermentation;and（4） when glucose is used as the sole carbon source,both the mass concentration and the yield of ethanol reach the maximum values,namely 25.93g/L and 0.39g/（L·h）,respectively.

    Purification and Structure Identification of Phytohemagglutinin-L4
    Zhang Xiao-yuan Guo Yong Wu Hui Zhao Qi Huang Min
    2010, 38(12):  145-150.  doi:10.3969/j.issn.1000-565X.2010.12.028
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    Mitogenetic glycoprotein PHA-L4 with high activity was obtained from phytohemagglutinin（PHA） after the separation and purification by means of anion exchange chromatography and biological activity inspection.The structure of the product was then identified by means of SDS-PAGE,mass spectrometry,N-terminal sequencing measurement and peptide mass fingerprint.The results indicate that PHA-L4 is a kind of glycoprotein tetramer composed of 4 PHA-L subunits,with a relative molecular mass of 120000,and that each subunit is heterogeneously glycosylated at the 12th Asn to a certain degree.

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