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Table of Content

    25 August 2010, Volume 38 Issue 8
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    Chemistry & Chemical Engineering
    Chemical Structure and Thermochemical Properties of Lignin from Herbaceous Plant
    Lou Rui Wu Shu-bin Lv Gao-jin Yang Qing
    2010, 38(8):  1-6.  doi:10.3969/j.issn.1000-565X.2010.08.001
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    Two representative herbaceous plants, namely, rice straw and bamboo, were selected as the materials to produce two kinds of enzymatic/mild acidolysis lignin （EMAL） by isolating lignin via an enzymatic/mild acidolysis process. Then, the chemical structure and properties of the products were characterized by means of elemental analysis, FT-IR and quantitative 31p-NMR, and the pyrolysis characteristics of the products were investigated by means of TG-FTIR and Py-GC/MS. The results show that （ 1 ） rice straw contains more pentosan and extractives while bamboo contains more cellulose and lignin; （2） guaiacyl units （G type） are abundant in rice straw EMAL while bamboo EMAL possesses more syringyl units （S type） ; （3） during the thermal degradation, there is one distinct weight loss peak at 384℃ in bamboo EMAL but two at 270℃ and 384℃ in rice straw EMAL;and （4） the difference in chemical structure greatly affects thermal decomposition behaviors as well as pyrolysis products of EMAL.

    Photochemical and Electrochemical Behaviors of Ferroceneylazobenzoic Acid Solution
    Ren Bi-ye Zhang Yi Li Chong-qing Liu Xin-xing Tong Zhen
    2010, 38(8):  7-11.  doi:10.3969/j.issn.1000-565X.2010.08.002
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    A novel amphiphilic ferroceneylazobenzoic acid （FcAzCOOH） with optical and redox activities was synthesized, and the product was identified and characterized by means of elemental analysis, 1H NMR and FT-IR. Then, the photochemical behavior of FcAzCOOH in tetrahydrofuran solution was invenstigated by means of UV-Vis, with an excellent photoisomerization behavior being discovered. Moreover, the electrochemical behavior of FcAz- COOH in polar DMF solution was analyzed by means of cyclic voltarnmetry. The results show that the electrochemical response of FcAzCOOH is dispersion-controlled and reversible, and that UV light has no obvious effect on the electrochemical behavior of FcAzCOOH.

    Analyses of Flow Path in Shell Side of Heat Exchangers and Heat Transfer Deviation of Baffling Flow from Counterflow
    Deng Xian-he Jiang Fu-hua
    2010, 38(8):  12-16,22.  doi:10.3969/j.issn.1000-565X.2010.08.003
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    The ratio of outlet temperature of hot fluid to that of cold one,a, which reflects the heat transfer depth, greatly influences the effective heat-transfer temperature difference. In order to investigate the relationship between the length-to-diameter ratio and the heat transfer depth of shell-and-tube heat exchangers, the heat transfer performance in the baffling flow region in the shell side is numerically analyzed via a flow path approach and is compared with that in the counterflow region. The results show that （ 1 ） at the critical point （ a = 1 ） of heat transfer, the heat transfer performance in the baffling flow region is far poorer than that in the eounterflow region, so that the baffling flow region should be kept far from the critical point; （2） as the deviation of heat-transfer temperature difference between the baffling flow region and the counterflow region Changes with a, the ratio of baffling flow area to the whole area should be controlled to prevent the deviation from being too large ; and （3） when a 〈 1, the ratio should be smaller than 0.6/R1a,c to keep the deviation within 5%. The reasons for the difficulty m achieving an a vatue less than 1 for large-scale heat exehangers are also revealed, and a multi-parallel ehannel strueture in the shell side is finally presented to inerease the heat transfer depth.

    Heat Transfer Model of Impermeable Protective Clothing with Cooling Vest
    Yan Ying Zhang Hui-ping
    2010, 38(8):  17-22.  doi:10.3969/j.issn.1000-565X.2010.08.004
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    With melamine resin as the shell and with encapsulated phase change material and was applied paraffin as the core, a cooling vest was prepared from micro- to the impermeable protective clothing. Then, the effects of wearing time on the chest temperature, the back temperature, the hand and leg temperatures, and the rectal temperature of the volunteer wearers of the protective clothing with and without the cooling vest were measured at a room temperature of 36 ℃ and with a relative humidity of 60%. Moreover, according to the empirical formula of heat production and dissipation in the human body and the Woodcock equation, the relationship between the average body temperature and the wearing time was investigated. The results show that the cooling vest greatly reduces the temperatures of such body parts as the chest, the back, the hand, the leg and the rectal, and that the modeling calculation results of the variations in the average body temperature with the wearing time accord well with the experimental ones.

    Influence of HPMA on Properties of Acrylate Latex and Corresponding Re-Rispersible Powder
    Zhang Xin-ya He Yan-ping Jiang Yu-ling Pei Yong-bing Chen Huan-qin
    2010, 38(8):  23-28.  doi:10.3969/j.issn.1000-565X.2010.08.005
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    Acrylate polymer latices with soft core and hard shell were synthesized via the emulsion polymerization of β-hydroxy propylmethacrylate （HPMA） and methacrylic acid （ MAA）, and the corresponding re-dispersible powder was also prepared. Moreover, the influence of HPMA dosage on the film-forming ability, the re-dispersibility and the water resistance of the original latex and its re-dispersible powder were discussed. Experimental results show that, at a HPMA dosage of 1.2% （mass fraction, the same below） , the film-forming ability and the water resist- ance behavior of the original latex and its re-dispersible powder are optimal and the re-dispersibility is well maintained. The absorbance analysis indicates that, when the HPMA dosage is not more than 1.2%, the powder possesses excellent re-dispersibility, high dispersity （ up to 90% ） and small mean absorbance variation （ less than 10% ）. DSC results show that the film of the original latex is of two glass transition temperatures; one is 6. 98℃ and the other is 30. 11 ℃, which means that the polymer particles have a two-phase core-shell configuration. This configuration is also verified by TEM photographs. Moreover, SEM results demonstrate that both the original latex and the re-dispersible powder are of excellent film-forming ability, and that micro-phase separation occurs during the film-forming of the original latex, which further testifies the core-shell configuration of the latex.

    Preparation of TiO2/AC and TiO2/ACF via Doping Modification and Photocatalytic Activities of the Products for Gas-Phase Toluene Degradation
    Xiao Xin-yan Yang Qing-shan
    2010, 38(8):  29-33,50.  doi:10.3969/j.issn.1000-565X.2010.08.006
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    Photocatalysts TiO2/AC and TiO2/ACF codoped with Fe and N irons were prepared via the sol-gel method, with butyl titanate as the precursor and, respectively, with activated carbon （AC） and activated carbon fiber （ACF） as the support. The products were then characterized by means of SEM, XRD and UV-Vis. Moreover, the influences of ion-codoping amount, inhibitor species, calcination temperature, carrier species and reuse times on the photocatalytic activities of the catalysts were experimentally investigated, with toluene as a model contamination. The results indicate that （ 1 ） the dispersive effect of TiO2 on ACF is better than that on AC ; （2） TiO2embeds into AC pores in the form of paricle but coats ACF surface in the form of film, and the two products are both in an anatase phase ; （3） the codoping of Fe and N ions significantly enhances the adsorption of visible light ; and （4） after a sintering for 2h at 500 ℃ with acetic acid as the inhibitor, the prepared TiO2/ACF with an ions dosage of 8% possesses the highest photocatalytic activity for gas-phase toluene degradation even if it has been reused for many times.

    Production of Fuel Ethanol from Paper Sludge via Simultaneous Saccharification and Fermentation
    Peng Lin-cai Chen Yuan-cai Fu Shi-yu Zhan Huai-yu
    2010, 38(8):  34-39.  doi:10.3969/j.issn.1000-565X.2010.08.007
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    Primary sludge from a toilet paper mill was used as biomass material to produce fuel ethanol via simulta- neous saeeharifieation and fermentation （SSF）, and three different non-ionic surfaetants, i.e. , Tween-20, Tween-60 and Tween-80, were evaluated for their ability to enhance SSF. The SSF process conditions were then optimized at a temperature of 36 ℃, with a substrate mass concentration of 100 g/L, an inoculums size of 6% （volume fraction）, and a cellulase dosage of 25 FPU/g. The results show that Tween-20 significantly accelerates the ethanol production. Specifically, the ethanol yield increases by 14% with a Tween-20 dosage of 0.2%. In the optimal conditions, the mass concentration of ethanol reaches 19.5 g/L after a 48 h incubation, which is 63.9% of the theoretical one. An analysis of the main chemical compositions of the paper sludge before and after SSF and of the fermentation liquor shows that a large amount of cellulose is converted into ethanol and only a small amount of hemicellulose is hydrolyzed, and that the hydrolysate xylose cannot be effectively used by yeast for ethanol production. Moreover, SEM results indicate that, after SSF, the long linear fibers in the paper sludge are destroyed and a lot of ellipsoidal yeast cells appear simultaneously.

    Exergy Analysis of Extractive Distillation for Fuel Ethanol
    Yang Hui Chen Li Yan Zong-cheng Wang Hong-lin
    2010, 38(8):  40-44.  doi:10.3969/j.issn.1000-565X.2010.08.008
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    In order to effectively produce fuel ethanol with low energy consumption, four columns of extractive distillation for fuel ethanol are analyzed by the exergy method. It is found that （ 1 ） the exergy efficiency of the prefractionator increases from 33.3% to 61.0% when the top pressure varies from 101. 325 kPa to 50 kPa and the feed is preheated by waste water in the bottom instead of by water vapor; （2） the exergy efficiency of the distillation column increases from 1.6% to 64. 0% when the top pressure improves from 101. 325kPa to 200kPa; （3） the exergy efficiency of the extractive distillation column increases from 25.0% to 29.0% after the addition of KAc in the extractant glycol; and （4） the exergy efficiency of the extractant recovery tower is up to 25.9%. All this demonstrates that exergy analysis is feasible in distinguishing the position of high energy consumption in an extractive distillation system.

    Chlorine Dioxide Bleaching Reinforced by Alkaline Extraction and Corresponding ECF Bleaching Sequences for Wheat Straw Pulp
    Zhao De-qing Chen Ke-fu Mo Li-huan Li Jun Xu Jun Yang Ren-dang Yang Fei
    2010, 38(8):  45-50.  doi:10.3969/j.issn.1000-565X.2010.08.009
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    Four kinds of alkaline extraction approaches, including the conventional, the oxygen-reinforced, the H2O2-reinforced and the oxygen-and-H2O2-reinforced ones （E, E0, Ep and E0p） , were used to modify ClO2-delignified （D0） wheat straw pulp, and the modification effects of these four approaches on the subsequent bleaching stage （D1） were explored. In addition, various elemental chlorine-free （ECF） bleaching sequences, such as D0ED1, D0P, DoA/QP, D0EP, D0EpD1 and D0EpP, were comparatively investigated. The results indicate that （ 1 ） the modification effects of different alkaline extraction approaches on the residual lignin of Do stage are different from one other; （2） for the subsequent D1 stage, the bleachability of D1 pulp varies in an order of D0E0P 〉 D0Ep 〉 D0E0 〉 D0E; （3） in the D0ED1 bleaching sequences, the increase of ClO2 dosage in D1 stage results in the brightness enhancement in a certain degree, especially at an optimized ClO2 dosage of 0. 8% -1.0% ; （4） as compared with the other sequences, D0EpD1 and D0EpP sequences are both of better bleaching effect; and （5） with D0EpD1 and DoEpP bleaching sequences, the final brightness of bleached wheat straw pulp reaches 82.3% ISO and 83.8% ISO, respectively, which means that both D0EpD1 and DoEpP sequences are applicable to the ECF short-sequence bleaching of wheat straw pulp.

    Enzymatic Properties of Urease Immobilized on Enzymic Dialdehyde Starch
    Luo Zhi-gang Yang Jing-feng Wang Min-ni
    2010, 38(8):  51-55.  doi:10.3969/j.issn.1000-565X.2010.08.010
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    This paper deals with the immobilization and properties of urease on enzymic dialdehyde starch. SEM results show that, as a carrier, enzymic dialdehyde starch aggregates after the immobilization. Moreover, it is found that （ 1 ） the content of urease immobilized on enzymic dialdehyde starch is up to 24.3 % ; （2） the optimal pH value and temperature for the immobilization are respectively 6. 0 and 70 ℃ ; （3） the immobilized urease is of excellent storage stability and large Michaelis constant; and （4） the activity of immobilized urease decreases only by 25% after being used for ten times. It is thus concluded that enzymic dialdehyde starch is an effective cartier for immobilized enzymes such as urease.

    Mechanical Engineering
    Motion Planning and Path Optimization of Manipulator for Holes Machining
    Zou Yan-biao Zhang Tie Chen Wei-hua
    2010, 38(8):  56-60.  doi:10.3969/j.issn.1000-565X.2010.08.011
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    In order to improve the processing efficiency, the motion planning and path optimization of a three-axis Cartesian coordinate manipulator, which is designed for the drilling of holes in piano chord axis plates, are investigated. In this investigation, the linear interpolation algorithm with parabolic transition is applied to the motion planning of the drilling, and a smooth trajectory with continuous position and velocity is generated. Then, a mathematical model describing the path planning for holes machining is established, with the shortest processing path as the object and with a collision-free way to bypass all the obstacles as the constraint. Moreover, a multi-layer genetic algorithm is used to find the solution to the mathematical model. Finally, six types of piano chord axis plates are used for algorithm verification. The results verify the effectiveness of the proposed algorithm.

    High-Speed Smoothing Interpolation Based on NURBS Online Fitting
    Li Fang Li Di Huang Xin
    2010, 38(8):  61-65.  doi:10.3969/j.issn.1000-565X.2010.08.012
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    In order to avoid the low average feedrate, discontinuous machining path and strong vibration shock in the machining process of consecutive micro line blocks, a real-time smoothing interpolation method based on NURBS curve fitting is proposed. In this method, by analyzing the geometric characteristics and machining tech- nique of the consecutive lines, a length ratio criterion and a critical angle criterion of adjacent lines are presented to pick out the appropriate point sequence. The point sequence is divided into many subsections based on the concave and convex criterion and is then fitted to obtain parametric curves. Finally, by combining the linear interpolation and the parametric curve interpolation, a high-speed smoothing machining is successfully implemented. Simulated and experimental results demonstrate that the proposed method effectively improves the machining speed, reduces the machining vibration and ensures the machining accuracy.

    Dynamic Analysis of Submersible In-Pipe Robot
    Zhao Da-xu Chen Bai Wu hong-tao Tian Fu-yang
    2010, 38(8):  66-71.  doi:10.3969/j.issn.1000-565X.2010.08.013
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    According to the force conditions of a submersible robot swimming in a fully-filled pipe, a dynamic model describing the 6-DOF （ Degree of Freedom） spatial motion of the robot is established based on Euler parameters （quaternion）. Then, for a robot swimming along the planned trajectory in a specific three-dimension pipeline, the fluid resistance is calculated with the CFD simulation software Fluent and is substituted into the proposed model to obtain the forces of the robot in the Mathematica environment. Moreover, a dynamic simulation utilizing the proposed model is performed to obtain the needed driving force when the robot swims in a determined crooked pipeline. With the use of Euler parameters （ quaternion）, singularities are effectively avoided.

    Process and Key Technologies of NC Electrochemical Machining of Integral Impeller via Fractional-Step Method
    Wang Fu-yuan Xu Jia-wen
    2010, 38(8):  72-77.  doi:10.3969/j.issn.1000-565X.2010.08.014
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    In order to solve the problems existing in the machining of the aeroengine＇s integral impeller, an improved electrochemical machining process, namely, the fractional-step method, is presented based on the one-step method. In the investigation, first, a fractional-step machining process of the blade is proposed. Then, the machining data of the blade are extracted via the section-cutting method. Moreover, with the help of a specific software for the electrochemical machining of the integral impeller, the processing region of different procedures are reasonably divided and the machining path is planned. Thus, the motion path of tool cathode and the displacements of the axes can be calculated, and the corresponding NC machining program can be generated. Finally, some machining tests are conducted to verify the feasibility of the proposed method. The results show that the proposed method effectively solves the key problems existing in the blade machining of the integral impeller and that it improves the sha- ping accuracy and shortens the preparation time.

    Investigation into Formation Mechanism of Nano-Crystalline/Ultra-Fine Grained Chip via Finite Element Method
    Wu Chun-ling Ye Bang-yan
    2010, 38(8):  78-82.  doi:10.3969/j.issn.1000-565X.2010.08.015
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    In this paper, first, a large-strain model describing the machining with large negeative rake angle and blunt round radius is established. Then, the effects of the tool rake angle and the blunt round radius on the chip shape, the effective strain and stress, the strain rate, the cutting temperature and the main cutting force during the cutting at a relatively low cutting speed are analyzed with the finite element software. The results indicate that （1） with the decrease in the tool rake angle and with the increase in the blunt round radius, the effective strain and stress, the strain rate, the cutting temperature and the main cutting force all increase, especially with the tool rake angle; （2） the effect of the blunt round radius weakens at a negative tool rake angle; and （3） large strains are imposed on the chip at a low temperature and a high stress and strain rate, which helps to produce nano-crystalline/ ultra-fine grained chip materials with high hardness by the cutting with large negative tool rake angle and low cutting speed.

    Experimental Investigation into Milling of Nickel-Based Powder Metallurgy Superalloy with Coated Tools
    Qiao Yang Ai Xing Liu Zhan-qiang Zhao Jun
    2010, 38(8):  83-88.  doi:10.3969/j.issn.1000-565X.2010.08.016
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    Milling experiments of nickel-based powder metallurgy superalloy using coated carbide tools were conducted to investigate the wear resistance of the tools, and the corresponding wear morphologies and mechanisms were analyzed by means of SEM and EDS. Then, the milling force and tool life were investigated by multi-factor orthogonal tests, and the corresponding empirical models were established by means of the least squares method and the regression analysis. Finally, the cutting parameters of coated carbide tools for the dry milling of nickel-based powder metallurgy superalloy were optimized based on the tool life-efficiency response surface methodology. The experimental results show that （ 1 ） the wear of the coated carbide tools is mainly abrasive and adhesive ; （2） the failure form of the tools varies with the cutting speed ; （3） the established models of milling force and tool life are highly significant in terms of the effect of the feed ; and （4） the optimal dry milling conditions are as follows ： a cutting speed of 40 -60m/min, a cutting depth of 0. 15 -0. 20mm, a radial cutting depth of 10 -20mm, and a feed of 0.08 - 0. 10 mm per tool.

    Energy-Receiving Performance of Two-Dimension Coil in Micro Electromechanical Systems
    Xue Kai-feng Huang Ping
    2010, 38(8):  89-94.  doi:10.3969/j.issn.1000-565X.2010.08.017
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    Based on the calculation methods of both the mutual inductance between two air-core coils and the self inductance of a ferrite-core coil, the energy-receiving performances of the two-dimension orthogonal windings of the coil in micro electromeehanieal systems （MEMS） are investigated. Then, the influences of the position and the angle of the energy-receiving coil as well as the ferrite core on the coupling coefficient of MEMS are analyzed. The results of theoretical analysis are finally verified through simulations and experiments. It is found that the two-dimen- sion orthogonal windings can compensate each other at different attitudes and prevent low transmission efficiency, and that the ferrite core significantly enhances the coupling ability of MEMS. In addition, a micro rectifying circuit meeting the requirement of miniaturization is designed and fabricated by selecting suitable electronic components. Experimental results on the self-developed MEMS using the fabricated circuit indicate that the efficiency and stability of the proposed wireless energy transmission system meet the practical requirements well.

    Food Science & Technology
    Emulsifying Properties of Cross-Linking Product of Peanut Protein Isolate and Decapterus maruadsi Protein Hydrolysate by Transglutaminase Treatment
    Hu Xiao Zhao Mou-ming Ren Jiao-yan Cui Chun
    2010, 38(8):  95-99,136.  doi:10.3969/j.issn.1000-565X.2010.08.018
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    Peanut protein isolate （PPI） was cross-linked with Decapterus maruadsi protein hydralysate （DPH） under the catalyzing of transglutaminase （TGase）, and oil-in-water emulsions of the samples were prepared via the high-pressure homogenization. Then, the effects of the cross-linking on the particle size distribution, the mean diameter per particle surface area, the microstructure and the centrifugal creaming rate of the emulsions were analyzed. The results indicate that （1） TGase accelerates the linkage between PPI and DPH with different hydrolysis degrees; （2） in the electrophoretograms of the cross-linked samples, the subunit bands with low molecular mass （ 14 -31 ku） disappear while the bands with high molecular mass （ more than 97 ku） appear; （3） the hydrolysis degree of DPH greatly improves the emulsifying properties of PPI-DPH, especially at a value of 5.5% ; and （4） the TGase cross-linking improves the emulsifying activity and emulsion stability of the cross-linked PPI-DPH.

    Optimization of Synergist of Antioxidant Peptide Derived from Egg White Protein
    Lin Song-yi Guo Yang Wang Ying Liu Jing-bo Zheng Lin Yin Yong-guang
    2010, 38(8):  100-104.  doi:10.3969/j.issn.1000-565X.2010.08.019
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    This paper focuses on the effects of single or complex addition of NaCl, carbohydrates, citric acid on the antioxidant activity of the peptide derived from egg white protein, with the DPPH scavenging activity as the evaluation index. Moreover, the best combination of synergist is optimized via the response surface methodology. The results show that （ 1 ） NaCl, maltose and citric acid all signifieantly improve the antioxidant activity of the peptide derived from egg white protein, so that they can be used as an antioxidant synergist independently; （2） the triadic combination of NaCl, maltose and citric acid is of the best enhancement effect ; and （3） in the optimal combination （ i. e. , 1.4% NaCl, 3.0% maltose and 0. 24% citric acid）, the synergist may result in a IC50 value on DPPH radicals of 0.27 mg/mL and a synergism value being up to 3.96.

    Properties of Gelatinized Corn Starch After Freeze-Drying
    Zhang Ben-shan Gao Ling-yun Chen Fu-quan
    2010, 38(8):  105-110.  doi:10.3969/j.issn.1000-565X.2010.08.020
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    In this paper, the physicochemical properties of gelatinized corn starch after vacuum freeze-drying were investigated by means of SEM, Brabender viscosity test and XRD. Then, the results were compared with those of native starch and of the pregelatinized starch after drum drying. It is found that （ 1 ） the majority of the freeze-dried gelatinized starch is loose and porous while the minority is fragmentary; （2） the trend in Brabender viscosity curve of the freeze-dried gelatinized corn starch is similar to that of native starch but is distinctly different from that of the pregelatinized starch ; （3） the XRD spectrum of the freeze-dried gelatinized corn starch is similar to that of the pregelatinized starch in terms of dispersion peak pattern, but its peak intensity is weaker; （4） the freeze-dried gelatinized corn starch is of the largest granular diameter （ i. e. , 110. 468 um） but of weak solubility in cold water and of relatively low transparency which is just a little higher than that of native starch; and （5） the freeze-dried gelatinized starch is characterized by a shear thinning behavior with low apparent viscosity and high thawing stability.

    Freezing Point Distribution and Impregnation Capacity of Refrigerant Liquids for Immersion Chilling and Freezing
    Han Guang-he Ni Ming-long Zeng Qing-xiao Zhu Zhi-wei
    2010, 38(8):  111-115.  doi:10.3969/j.issn.1000-565X.2010.08.021
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    In this paper, refrigerant liquids containing three or four components such as ethanol, propylene glycol, salt and water were prepared, and the relationship between the freezing points and the components of the refrigerant liquids were analyzed via the temperature-time method. Then, the impregnation of the refrigerant liquids in gelatin gel model was investigated by means of the silver nitrate titration and the gas chromatography. The results indicate that （ 1 ） when the mass fraction of the solutes is larger than 45 %, the ternary refrigerant liquid consisting of ethanol, propylene glycol and water is of a freezing point lower than that of the ethanol solution with the same solute mass fraction, especially at a ethanol mass fraction varying from 20% to 30% ; （2） NaCl has the greatest effect on the decrease of the freezing point of the quaternary refrigerant liquid ; and （3） as compared with the common salt or ethanol solutions, the quaternary refrigerant liquid consisting of ethanol, propylene glycol, sodium chloride and water is of the lowest solute impregnation capacity. Thus, it is concluded that the quaternary regrigerant liquid is more suitable for immersion chilling and freezing due to its low freezing point, solute mass fraction and impregnation capacity.

    Characteristics and Mathematical Description of Hot-Air Drying of Camellia oleifera Seed
    Zhang Xi-mei Wu Xue-hui Li Chang-bao Kou Qiao-hua Li Li
    2010, 38(8):  116-120.  doi:10.3969/j.issn.1000-565X.2010.08.022
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    The drying procedure is extremely important to the storage and processing of Camellia oleifera seed and to the quality of Camellia oil. In order to optimize the drying technology and reduce energy consumption, the effects of hot-air drying, microwave drying and natural drying on the stability of oil were analyzed, and the law of the effects of temperature and bulk density on the drying characteristics of Camellia oleifera seed is investigated. Then, a mathematical model describing the drying procedure is established by integrating the three models. The results show that （1） hot-air drying is more suitable for Camellia oleifera seed; （2） the drying rate increases with the increase of temperature and with the decrease of bulk density; （3） it takes 20, 15 and 13 h respectively to attain a relative safe moisture content for storage at the drying temperatures of 40, 55 and 70 ℃ ; and （4） the drying time cost reaches 15, 20, 22 and 25 h when the bulk densities are 322, 354,430 and 442 kg/m3 , respectively. Moreover, it is demonstrated by the linear regression of the three common drying models that the Page model accurately describes the hot-air drying process of Camellia oleifera seed, with an average relative error of 5.72% between theoretical values and experimental ones. It is, thus, concluded that, for the drying of Camellia oleifera seed, the Page model can predict the drying rate and moisture content more accurately.

    Optimization and Comparison of Fingerprints of Triterpenoids from Ganoderma lucidum and Ganoderma sinense
    Huang Sheng-quan Wei Gang Yao Song-jun Liu Cui-ling Ning Zheng-xiang
    2010, 38(8):  121-125.  doi:10.3969/j.issn.1000-565X.2010.08.023
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    By optimizing the experimental conditions of high-performance liquid chromatography （ HPLC）, a method of fingerprint analysis of Glossy ganoderma was presented and a common mode of the fingerprints of Ganoderma lucidum and Ganoderma sinense was proposed, which were both initially used to estimate the quality difference. The HPLC conditions were optimized as： acetonitrile-2% acetic acid solution （gradient elution） as a mobile phase, a detection wavelength of 252 nm, a flow rate of 1 mL/min and a column temperature of 35 ℃. In the optimal conditions, 29 common peaks were separated from 14 batches of Ganoderma lucidum and 7 batches of Ganoderma sinense, and three compositions （ganoderic acids A, C2, G） were identified. The results indicate that the peak of ganoderic acid A is of the strongest intensity ; and that although the relative ratio of common peaks of Ganoderma lu- cidum is close to that of Ganoderma sinense, the peak area per unit medicine of Ganoderma sinense is only about 5% -10% of that of Ganoderma lucidum, which means that the quality evaluation of the products from Glossy ganoderma should combine both the HPLC fingerprint and the content determination. Moreover, according to the fingerprints of triterpenoids from Glossy ganoderma obtained by the optimized method, it is found that the Ganoderma lucidum contains much more triterpenoid compositions than what is reported in the literature, and that the triterpenoids in Ganoderma sinense can be easily detected. It is, thus, concluded that the proposed method is reliable, accurate and reproducible.

    Analysis of Microbial Community Structure by ERIC-PCR Fingerprint for Sufu Fermentation
    Geng Yu-huan Li Guo-ji Zou Jia-xing
    2010, 38(8):  126-130.  doi:10.3969/j.issn.1000-565X.2010.08.024
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    In order to develope a culture-independent molecular marker to monitor the changes of microbial community structures in industrial sufu fermentation, samples from the fermentation prophase, the intermediate stage （primary metaphase and secondary metaphase） and the anaphase during the whole fermentation process were collected. The total DNA was extracted and the DNA fingerprints were generated by means of ERIC-PCR. The results show that （ 1 ） the samples collected from four different fermentation stages of the same batch are of the same ERIC-PCR bands at 500 and 750 bp, meaning that some microbes are active in the whole fermentation process; （2） each fermentation stage yields its unique bands; and （3） the ERIC-PCR fingerprints corresponding to the four samples weekly collected from different batches are identical, with a Sorenson pairwise similarity coefficient （Cs） varying form 59% to 100%.

    Environment Science & Technology
    Degradation of Nitrobenzene Wastewater by Three-Dimension Electrode Method Coupling Electro-Fenton
    Xiao Kai-jun Wang Xin Yin Yu-rong
    2010, 38(8):  131-136.  doi:10.3969/j.issn.1000-565X.2010.08.025
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    Nitrobenzene wastewater was treated by a three-dimension electrode method coupling electro-Fenton, and the factors affecting the organic matter degradation as well as the treatment efficiency were investigated. The results were then compared with those of the three-dimension electrode method and the common electrode-Fenton method. It is found that （ 1 ） with the increase in electrolysis time, initial pH value, polar distance, cell voltage, Fe 2 ＋ dosage and aeration rate, both the chemical oxygen demand （COD） and the nitrobenzene removal first increase and then decrease or change slightly; （2） the optimal conditions for the wastewater treatment are found to be： an electrolysis duration of 2.0 h, and initial pH value of 3.0, a polar distance of 6 cm, a cell voltage of 30 V, a Fe 2＋ dosage of 1.0 g/L and an aeration rate of 0. 8 m3 /h ; and （3） in the optimal conditions, the removals of COD and nitrobenzene reach 93.1% and 96. 5%, respectively. In addition, according to the GC-MS results of the intermediate products, the degradation mechanism of nitrobenzene is explored and the superiority of the method over the three-dimension electrode method and the common electrode-Fenton method in terms of nitrobenzene removed is validated.

    Catalytic Reduction of Nitrate Nitrogen by Nano-Sized Bimetallic Pd-Cu/SnO2 Catalyst
    Cheng Jian-hua Hu Yong-you Wu Yi-bao
    2010, 38(8):  137-141,146.  doi:10.3969/j.issn.1000-565X.2010.08.026
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    Nano-sized SnO2 and bimetallic Pd-Cu/SnO2  catalysts were successfully prepared via the thermal decomposition method and the impreganation method, respectively. Then, the nano-sized SnO2 was characterized by means of XRD, TEM and specific surface area analyzer, etc. , and the catalytic reduction activity and selectivity of the nano-sized Pd-Cu/SnO2  for nitrate nitrogen were analyzed at atmospheric pressure, with formic acid as the reducing agent. The results show that （ 1 ） the prepared nano-sized SnO2 is of a crystalline size of about 8.9 10. 4 nm or 9.3- 10. 7 nm, with a particle size of about 10. 0 nm and a BET specific surface area being up to 144. 9892m2 /g; and that, in the catalytic reduction of nitrate at a Pd-to-Cu ratio of 6：1 and a formic acid dosage of 16. 0mmol/L, nitrate is completely reduced; 76.23% of the total nitrogen is removed; the catalytic activity reaches 0. ll9mmoL/（min· g） ; and the optimal pH value is 4.0

    Factors Affecting Photocatalytic Degradation of Formaldehyde by Nano-Sized Titania
    Shen Wen-hao Long Zhou Chen Xiao-quan Li Dong-xun
    2010, 38(8):  142-146.  doi:10.3969/j.issn.1000-565X.2010.08.027
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    In order to evaluate the photocatalytic degradation capacity of self-prepared nano-sized TiO2 for the organic pollutants in the air, a self-developed photocatalytic degradation reaction system was adopted to analyze the photocatalytic degradation process of formaldehyde and to investigate the factors influencing the degradation, such as the relative humidity, the illumination intensity, the gas flowrate and the initial mass concentration of formaldehyde. The results indicate that the photocatalytic degradation performs best at a relative humidity of 50% and a gas flowrate of 1.20 L/min; and that the photocatalytie degradation rate does not increase unlimitedly with the increase in illumination intensity, but it decreases with the increase in the initial mass concentration of formaldehyde.

    Degradation of Tetracycline Hydrochloride in Aqueous Solution by Ultrasonic Irradiation
    Ma Yan Gao Nai-yun Yao Juan-juan Guo Hong-guang Zhang Ke-jia
    2010, 38(8):  147-152.  doi:10.3969/j.issn.1000-565X.2010.08.028
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    This paper deals with the ultrasonic degradation of tetracycline hydrochloride （TC.HCl） in aqueous solution and reveals the effects of ultrasonic frequency, ultrasonic power, initial mass concentration of the solution, pH value and anion on the degradation efficiency. The results indicate that （1） with ultrasonic irradiation, TC . HCl in aqueous solution effectively degrades with high speed, which accords with the pseudo first-order reaction model; （2） at a pH value of about 5.60, 88. 17% of 1.00mg/L TC . HCl is decomposed within 20min under the irradiation with 400 kHz and 100 W ultrasonic ; （3） the degradation rate of TC . HCl increases with the increase in ultrasonic power and with the decrease in the initial TC . HCl concentration; （4） the pH value of the solution greatly influences the TC . HCl degradation and the degradation performs well in alkaline condition; and （5） Cl- and SO4 2- slightly inhibit the degradation, while NO3- , HCO3-、 and HPO4 2- accelerate the degradation, especially the latter two.

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