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Table of Content

      
    16 July 2009
    Volume 44 Issue 7
    Articles
    Isolation and characterization of  antibacterial factor AF1
    produced by Penicillium griseoroseum
    YANG Wei-Hua, LEI Xue-Mei, ZHANG Wei-Can, GAO Pei-Ji-
    J4. 2009, 44(7):  1-4. 
    Abstract ( 806 )   PDF (502KB) ( 797 )   Save
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    An antimicrobial factor termed AF1 was isolated from culture broth of Penicillium griseoroseum. The filtered fermentation broth underwent centrifugation and ultrafiltration (membrane cutoff 5?kD). Then it was purified using Sephadex LH20 and highperformance liquid chromatography (HPLC). The molecular weight of AF1 was 1465 Da. AF1 was stable to βlactamase, hydroxylamine, acid, alkali and heat. Together, these data indicate that AF1 is a novel antibacterial factor which is different from penicillin. The molecular structure of AF1 shows characteristics of saccharide and amid. MIC of AF1 versus Staphylococcus aureus is 80?μg/ml, and AF1 is effective to drugresistant S. aureus. It is difficult to induce bacterial resistant to AF1.

    Effect of intraperitoneal injection of indigowoad ro ot polysaccharide on
    antioxidant enzyme activity and MDA content in the liver of Pelodiscus sinensis
    J4. 2009, 44(7):  5-7. 
    Abstract ( 773 )   PDF (247KB) ( 824 )   Save
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    The effect of intraperitoneal injection of indigowoad root polysaccharide (IRPS) on the oxidation resistance was studied in the liver of Pelodiscus sinensis. There were four groups in this experiment and every group was continuously injected for three days. The first three groups were injected with 1.5?mg IRPS,3?mg IRPS, and 6?mg IRPS respectively. The fourth group was injected with physiological saline. The results showed that the activities of SOD, CAT and GSHPX increased and MDA content decreased in the first three groups injecting with IRPS. However, there were some differences among them. Compared with the control, CAT activity significantly increased in the first three groups injected with IRPS and the activity increased with an increase of injection dosage. GSHPX activity increased significantly and MDA content obviously decreased by injecting with 3?mg and 6?mg IRPS in  P.sinensis, but the greatest  effect was shown by injecting with 3?mg IRPS in  P.sinensis. The effect on SOD activity was not significant by injecting with 1.5?mg and 3?mg IRPS in  P.sinensis. The effect of the group by injecting with 6?mg IRPS  in  P.sinensis  is the most significant difference. In a word, IRPS could improve the oxidation resistance in the liver of P.sinensis.

    Study of the method of microwave irradiation for 
    bleaching wheat straw pulp
    J4. 2009, 44(7):  8-12. 
    Abstract ( 739 )   PDF (391KB) ( 649 )   Save
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    The results of bleaching wheat straw pulp were analyzed using the method of microwave radiation. The results showed that bleaching time, surplus peroxide and the pulp viscosity were lessened compared to bleached pulp of microwave radiation with water bath experiment. The influence of peroxide dosage on bleaching pulp is the most obvious, and the next is irradiation time and NaOH, and irradiation power is the least by orthogonal experiments of four factors. The most optimum conditions are, irradiation power 240W, reaction time 25min, H2O2 5%, and NaOH 4%. The pulp brightness is about 59%, pulp viscosity is more than 620?mL·g-1, and K value is 390.

    The preparation of sizecontrolled silver nanoparticles in aqueous 
    phase by an electrochemical method
    J4. 2009, 44(7):  13-17. 
    Abstract ( 693 )   PDF (876KB) ( 807 )   Save
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    A novel electrochemical method for synthesis of sizecontrolled silver nanoparticle in the aqueous phase under the protection of sodium dodecyl benzene sulfonate (SDBS) was  established, which was ther used as the stabilizer for the silver clusters. The protective mechanism of SDBS in the electrochemical synthesis of silver particles was also discussed.  A rotating electrode system was used to study the effect of several key experimental parameters such as stirring mode, electrolysis time, rotation speed and electrolysis current on particle size and distribution. The  obtained  silver nanoparticles were characterized by means of powder Xray diffraction (XRD) and scanning electron microscope (SEM).

    Study of catalysts for synthesis of Schiff bases under microwaveassisted
    J4. 2009, 44(7):  18-21. 
    Abstract ( 727 )   PDF (172KB) ( 363 )   Save
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    Compared with the conventional stirring method a study of catalysts and microwave power for the synthesis of Schiff bases under microwave irradiation was performed.  In addition, three kinds of catalysts —— NaHSO4, AlCl3 and SbCl3 —— were employed in order to compare their catalytic activities for the synthesis of Schiff Bases. The products were characterized by IR, 1H NMR, and elemental analysis. This demonstrated that the procedure involved a short reaction time and moderate reaction conditions. Microwave power of  800?W was optimum for the reaction, and SbCl3 exhibited higher catalytic activity than the others. 6 mol% of catalyst was sufficient to accelerate the reaction.

    Synthesis of micro/mesopous zeolites by degrading ze olite NaY as precursors and using CTMABr as a template
    J4. 2009, 44(7):  22-25. 
    Abstract ( 818 )   PDF (969KB) ( 768 )   Save
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    The objective of the research was to explore the optimum conditions to synthesize materials with graded pores and high hydrothermal stability which are potential candidates for catalysts. The methods of synthesizing Micro/mesoporous zeolites were that CTMABr(cetyltrimethylammonium bromide)was used as the template and Y precursors were obtained by degradation of NaY zeolites. The results of  XRD and FTIR suggested that the composites have an interconnected hierarchical micro  meso porous structure, with the mesoporous remains existing after the treatment at 750?℃ in 100% vapor for 2?h. The conclusion is that the materials synthesized in the optimum conditions with graded pores and high hydrothermal stability, are different from those obtained from the process of direct synthesis of precursors, and also degradation of waste zeolites has the advantages of reclaiming waste zeolites and cutting the cost.

    Optical properties of CaH2 at a certain pressure
    J4. 2009, 44(7):  26-28. 
    Abstract ( 758 )   PDF (792KB) ( 729 )   Save
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    The optical properties of single crystal CaH2 were investigated by the methods of plane wave pseudopotential density functional theory in a range of hydrostatic pressure from 0 to 500?GPa. The calculation results showed a blue shift at absorption wavelength with the pressure increasing. According to the absorption spectrums, CaH2 can not keep good transparency in a range of hydrostatic pressure from 0 to 500?GPa. The calculated lattice constants were in good agreement with the experimental data.

    Projectile impact and penetration in a twodimensional g ranular bed  
    J4. 2009, 44(7):  29-32. 
    Abstract ( 853 )   PDF (1084KB) ( 592 )   Save
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    Projectile impact and penetration in a 2D granular bed under the acceleration due to gravity was been studied by fast video photograph and acceleration sensors. The distribution of displacement of the granular bed after impact can be clearly observed by highspeed video photograph. Granular jet formation and the penetration regime of the projectile shown in the experiment,  reflect the properties of energy dissipation of granular mediums. The acceleration sensor can directly measure drag forces of the projectile in the movement, and  these forces compare with hydrostatic drag forces during penetration. Experimental data obtained by comparison showed that considerable drag forces act on the projectile and these forces are related to velocity.

    A new class of memory gradient methods with Wolfe line search
    J4. 2009, 44(7):  33-37. 
    Abstract ( 735 )   PDF (230KB) ( 848 )   Save
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    A new class of memory gradient methods for unconstraind optimization problems was presented. Its global convergence and linear convergence rate were proved under some mild conditions. The methods are suitable to solve large scale optimization problems by using the current and previous iterative information, which generate the descent direction and avoiding the computation and the storage of some matrices. Numerical experiments show that the new methods are more efficient then FR, PRP, HS conjugate gradient methods and the steepest descent method under the condition of the Wolfe line search.

    Joint test in nonlinear regression models with AR(2) random errors
    J4. 2009, 44(7):  38-43. 
    Abstract ( 769 )   PDF (237KB) ( 467 )   Save
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    Based on the test of homogeneity for variance and correlation in nonlinear regression models with AR(2) errors, the likelihood ratio test and Score test are first discussed. Then, based on the parameter orthogonality transformation, both the modified likelihood and the modified Score tests are obtained. The results in Reference [1] are extended.

    Matching method estimate of the average treatment effect of
    a job training program
    J4. 2009, 44(7):  44-48. 
    Abstract ( 986 )   PDF (239KB) ( 572 )   Save
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    Step regression and AIC are applied to estimate the propensity score. Based on the weighting propensity score estimator(WPSE) and propensity score matching estimator(PSME), the weighting propensity score matching estimator(WPSME)is proposed. Then the three methods of WPSE、PSME、WPSME are compared by simulating using the bootstrap method. It is shown that WPSME is more precise and more efficient than the other methods in terms of bias and standard deviation.  Finally, the average treatment effect of the job training program is estimated with WPSME.

    SIS model with a feedback mechanism on sparsely distributed regular  lattices
    J4. 2009, 44(7):  49-54. 
    Abstract ( 722 )   PDF (925KB) ( 861 )   Save
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    An SIS model related to feedback mechanism, crowddensity and crowd moving on sparse distributed regular lattices is proposed. It is shown that  feedback greatly  impacts on the stable infected ratio but does not impact on the spreading threshold of the system. If the spreading efficiency is fixed, the crowddensity is larger and the stable infected ratio is higher. Moreover, there is a crowddensity threshold in this model. Only when the crowddensity is above the threshold,  the disease continuously and steadily spread in a crowd.  The stable infected ratio of a moving crowd is higher than that of a static crowd in the case of low crowddensity, which indicates that the moving activity of individuals can promote the disease spread in the case of low crowd density.

    A new approach for finitetime stabilization for a class of nonlinear systems
    J4. 2009, 44(7):  55-61. 
    Abstract ( 690 )   PDF (381KB) ( 431 )   Save
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    Finitetime stability is investigated for a class of nonlinear systems, and a sufficient condition for globally finitetime stability is obtained. Globally finitetime stabilizability is achieved by designing a continuous and nonsmooth state feedback nonlinear system. Compared with previous results, the new method may accelerate convergent speed and decrease the settling time.

    Harnack inequality for diffusion semigroups
    J4. 2009, 44(7):  62-65. 
    Abstract ( 683 )   PDF (185KB) ( 737 )   Save
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    A new criterion for the Harnack inequality of general diffusion semigroups is given.

    A wideneighborhood predictorcorrecting algorithm for
    linear programming
    J4. 2009, 44(7):  66-70. 
    Abstract ( 831 )   PDF (230KB) ( 993 )   Save
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    A new interior point wideneighborhood predictorcorrecting algorithm is presented for a linear programming problem. On the basis of the idea of a predictorcorrecting algorithm, the iteration of our algorithm is faster in a wideneighborhood than in a narrow one. The concrete steps of the algorithm are introduced, its computational complexity is discussed, and the results indicate that the algorithm is a polynomialtime one. The validity of the algorithm is confirmed though a numerical experiment.

    Modeling in fedbatch fermentation and its parameter 
    identification based on HPSO algorithm
    J4. 2009, 44(7):  71-78. 
    Abstract ( 752 )   PDF (486KB) ( 263 )   Save
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    Modeling and its parameter identification are investigated in glycerol bioconversion to 1,3propanediol (1,3PD) by Klebsiella pneumoniae (K.pneumoniae) in fedbatch cultures. Considering the discontinuity of adding glyceroland alkali in the process, a nonlinear multistage dynamical system is presented to formulate the process. Taking the minimal errors between the experimental data and calculated values as the performance index, we propose an identification model and prove the existence of optimal kinetic parameters. Finally, a hybridparticle swarm optimization (HPSO) algorithm is constructed to solve the identification model. Numerical results show that the error is reduced by 176%~4177% and the proposed dynamical system can better formulate the fedbatch culture.

    Multiple positive solutions for pLaplacian boundar y value problems
    J4. 2009, 44(7):  79-82. 
    Abstract ( 770 )   PDF (161KB) ( 378 )   Save
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    Using fixed index point theorems and iterative technique, this paper is concerned with the existence and nonexistence of positive solutions for the pLaplacian differential equations.  We obtained the dependence of the positive solutions on the parameter λ.

    An online estimation algorithm of driver’s learning process
    J4. 2009, 44(7):  83-88. 
    Abstract ( 698 )   PDF (560KB) ( 553 )   Save
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    To simulate human decisionmaking in steering to follow a planned path, we modeled the driver’s learning process by using an idea of target position. The proposed model dealt with the driver’s decisionmaking mechanisms in tracking a target position by means of a NeuroFuzzy system. Here, a cubic Bspline curve was used to generate more flexible paths of lanechange to a target position. Furthermore, a learning algorithm was proposed to emulate a driver’s selflearning skill from his driving experience by splitting the fuzzy area into a number of linear systems to approximate the nonlinear function locally and online. Results from the simulation of the obstacle avoidance showed the capability of the proposed model to simulate a driver’s steering behavior with emphasis on learned skill.

    Research on QoSbased Web service discovery
    J4. 2009, 44(7):  89-91. 
    Abstract ( 794 )   PDF (317KB) ( 382 )   Save
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    Quality of Service (QoS) is a key point in application. But the Web Services Description Language (WSDL) and Universal Description Discovery & Integration (UDDI) standards support the specification, publication and discovery of Web services based only on functional aspects. To solve this problem this paper proposes a QoSbased Web service description and discovery model, provides the implementation framework, and gives a system deployment and implementation plan.

    Positive solutions for 2nthorder superlinear  
    semipositive boundary value problems
    J4. 2009, 44(7):  93-96. 
    Abstract ( 738 )   PDF (141KB) ( 540 )   Save
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    Without requiring the nonlinearity f(x,y) to be continuous and be lower bounded, when f(x,y) satisfies the Caratheódory condition, it is proved that there exists positive solutions to a class of 2nthorder superlinear semipositive boundary value problems. Our work improves some known results.