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    25 October 2016, Volume 44 Issue 10
    Mechanical Engineering
    ZHANG Xiao-tao LI Wei-guang
    2016, 44(10):  1-7.  doi:10.3969/j.issn.1000-565X.2016.10.001
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    In order to remove the power interference in the vibration displacement signals of a novel tilting-pad journal bearing with fluid pivot,a power interference removal algorithm based on the harmonic wavelet and the singular value decomposition ( SVD) is proposed.In the algorithm,first,the frequency domain containing the power frequency is extracted by using the harmonic wavelet that has strict box-like spectrum and arbitrary detail of arbitrary frequency domain.Then,a Hankel matrix is constructed in the time domain,the singular value decomposition is performed,and the singular values relevant to the power frequency are set to be zero,thus removing the power frequency.Finally,all the sub-bands without power frequency are merged with the other sub-bands of the original frequency spectra.Thus,the time domain signals without the power interference are achieved for a further study.Experiment results show that the proposed algorithm can effectively remove the power interference.This algorithm helps to investigate the vibration characteristic of the novel tilting-pad journal bearing,and it is both practical and feasible.

    ZHANG Sai-jun GONG Xiao-long LI Jian-qiang ZHOU Chi YUAN Ning
    2016, 44(10):  8-14.  doi:10.3969/j.issn.1000-565X.2016.10.002
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    The tensile samples of different grain sizes were obtained by heating 0. 1,0. 2,0. 4,0. 6,0. 8 and 1. 0mm T2 copper at 450,650 and 850 ℃.Then,the deformation of the samples in uniaxial tension tests was measured by the digital image correlation (DIC) method,and the relationships between the relevant parameters (namely,the yield strength,the tensile strength,the maximum uniform strain and the fracture strain) and the grain size as well as the sheet thickness are evaluated.Experimental results show that the mechanical properties of the annealed T2 copper sheet show an obvious size effect; specifically,the tensile strength,the maximum uniform strain and the fracture strain decrease with the decrease of the sheet thickness or the increase of the grain size,and they all have an approximate exponential relationship with the ratio of the sheet thickness to the grain size.

    WANG Nian-feng LAO Kun-yi ZHANG Xian-min
    2016, 44(10):  15-21,29.  doi:10.3969/j.issn.1000-565X.2016.10.003
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    In the amputee rehabilitation,the anthropomorphic prosthetic hand of light weight,small size and most of the grasping and operating functions of human hands is needed.In this paper,by analyzing the skeletons and functions of human hands,a design of the anthropomorphic prosthetic hand is proposed.The prosthetic hand has five fingers and four degrees of freedom (DOFs),and is driven by four independent actuators.The joints of each finger are designed based on elastic joints,and the adjacent phalanxes are connected by using helical springs.Ex- cept for the thumb,each finger is of one DOF,and the movements among the joints are realized by using tendons to couple the joints.The compact drive system is settled in the palm to control the fingers.Through the analysis of the finger workspace and the simulation of the prosthetic hand,it is proved that the proposed prosthetic hand can execute most gestures and grasping tasks in the activities of daily life.

    ZHANG Xian-min HU Kai WANG Nian-feng GUO Hao
    2016, 44(10):  22-29.  doi:10.3969/j.issn.1000-565X.2016.10.004
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    In the field of structural design,thermal effects have been extensively discussed.In this paper,based on the topology optimization method,the design of the thermally-driven compliant mechanism is investigated,and a corresponding parallel penalization model is constructed.The core of this model is to decompose a complex multi- ple-material thermal-mechanical coupling problem into a series of single-material thermal-mechanical coupling sub- problems.Then,the sub-problems are solved concurrently,and according to the requirement of the overall system,the solutions to all the sub-problems are coordinated so as to achieve the solution to the original problem.For all the sub-problems,the thermal-mechanical coupling optimization models are constructed based on the solid isotropic ma- terial with penalization (SIMP) model,and then the sequential coupling method is adopted to conduct the thermal- structural coupling physics analysis,thus achieving concurrent and independent solutions.The constructed model is simple in concept and practice and can be used to handle an arbitrary number of candidate materials.In addition,it can avoid fragile topologies and is,therefore,helpful in manufacturing.Finally,the effectiveness of the construc- ted model is verified by several numerical examples.

    LI Jing CHEN Hao YIN Yao-bao
    2016, 44(10):  30-35,42.  doi:10.3969/j.issn.1000-565X.2016.10.005
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    In order to analyze the influence of the radial micro-motion of piston-cylinder interface on the oil charac- teristic,based on the theory of dynamic pressure supporting,the oil shape in the piston-cylinder interface with dif- ferent pressure and rotating speeds as well as its change is simulated.Then,a hydraulic pump is tested by using a service life test bench,and the test results are compared with the theoretical ones.The results show that (1) with the radial micro-motion,there exists a minimum oil thickness,and the pressure in the interface is higher than that in the cylinder; (2) the thickness in the pressing area linearly increases with the increase of pressure; (3) as the rotating speed increases,the thickness in the pressing area decreases and the decrease tends to become smaller; (4) when the turning angle is 90°,the thickness reach the minimum value; (5) in the absorbing area,the mini- mum oil thickness is irrelevant to the rotating speed,and it is smaller than that in the pressing area; and (6) the position of the minimum oil thickness is consistent with the direction of the centrifugal force.

    SUN Ze-gang XIAO Shi-de XU Ming-heng WEI Wei
    2016, 44(10):  36-42.  doi:10.3969/j.issn.1000-565X.2016.10.006
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    In order to find a way to restrain the cavitation of hydraulic components from the structure,the influence of the axial piston pump cylinder kidney shape hole structure on the self suction of the plunger cavity is theoretically analyzed,and the plunger cavity cavitation is simulated by using the Fluent software.Then,based on the princi- ple of the Kriging interpolation,an agent model is constructed by taking the structure parameters of the cylinder kidney shape hole as the independent variable and the gas volume fraction of the plunger cavity as the objective function value.Moreover,the constructed agent model is optimized by using the cross breeding particle swarm al- gorithm,thus obtaining the optimized structure of the cylinder kidney shape hole,which provides a new method to overcome the strong coupling relationship between the structure parameters of the axial piston pump.According to the above analysis,the structure and parameters of the cylinder kidney shape hole and the valve plate groove of the axial piston pump,which can maximize the inhibition of the plunger cavity cavitation,are obtained.Simulation re- sults demonstrate that the obtained structure can significantly inhibit the plunger cavity cavitation.

    Mechanics
    JIANG Zheng-rong ZHONG Yu-kai SHI Kai-rong LUO Bin
    2016, 44(10):  43-48,56.  doi:10.3969/j.issn.1000-565X.2016.10.007
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    Through the dimensional analysis,a comparability rule expression of single-layer reticulated shells sub- jected to a vertex impact is derived in this paper,which considers the gravity and the strain-rate effect of relevant materials.On this basis,two methods of preparing material specially and adding extra mass are proposed to meet the scaling requirements.Then,a model according well with available literaturesis constructed by using the non- linear finite element software LS-DYNA,and it is proved to be reliable by comparing the experimental results with- the simulation ones.Finally,two analytical models of Kiewitt-Lamella single-layer reticulated shells are respec- tively constructed to verify the proposed two methods by comparing their node displacements.The results show that the proposed two methods can both accurately predict the displacement of the prototype,with the relative error ab- solutes of less than 15% and 12% respectively,and they can both accurately predict the collapse modes of the pro- totype,especially the whole collapse,and that the method of adding extra mass is better in terms of precision and maneuverability.

    LIU Yi-ping WU Tu-hua LIU Ze-jia JIANG Zhen-yu TANG Li-qun
    2016, 44(10):  49-56.  doi:10.3969/j.issn.1000-565X.2016.10.008
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    The foam-filled concrete (FFC) is expected to become a new type of arresting material for the engi- neered material arresting system (EMAS). In order to investigate the mechanical properties of the FFC material un- der the quasi-static compression,six FFC specimens of different expanded polystyrene (EPS) fractions (volume fraction) were manufactured to carry out the quasi-static compression experiments.Then,by analyzing the experi- mental data,the stress-strain curves were fitted by using sectional curves,and the relationships between the fitting parameters and the EPS fraction were determined.Finally,a constitutive model of the FFC material under the qua- si-static compression was constructed.The results show that (1) the stress-strain curve of the FFC material under the quasi-static uniaxial compression can be divided into three parts,namely,the elastic stage,the plastic platform stage and the densification stage; (2) the compressive strength of the FFC material decreases with the increase of the EPS fraction; and (3) the constructed constitutive model accords well with the experimental data,and can ac- curately describe the compressive mechanical properties of the FFC material of different EPS fractions.

    HE Yan-bin YAO Xiao-hu CHENG Shi-chao LONG Shu-chang ZHANG Xiao-qing
    2016, 44(10):  57-64,80.  doi:10.3969/j.issn.1000-565X.2016.10.009
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    Drop weight tests were carried out on the polyurethane foam and T700/3234 carbon fiber panel sandwich specimen based on the ASTM D7766/D7766M—15 experiment standard.Then,the dynamic responses of the com- posite foam sandwich plates with different foams and punches were analyzed under different impact energy.The re- sults show that (1) there exist three types of damage models for the dynamic responses; (2) as the impact energy increases,the peak impact force of the upper panel increases and reaches the peak value in lesser time,and the structure damage of the upper panel starts earlier and continuously increases,with an increase of the compression of the foam sandwich plates; (3) the upper panel of the higher density foam sandwich plates has a higher peak force value and a smaller displacement with more absorbed impact energy,and the corresponding lower panel has smaller deformation and strain with a stronger capability to resist the deformation; and (4) the punch of a smaller diameter has a stronger penetration,which can lead to a smaller upper panel strain and a larger lower panel strain.

    HUANG Huai-wei ZHANG Yong-qiang HAN Qiang
    2016, 44(10):  65-69.  doi:10.3969/j.issn.1000-565X.2016.10.010
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    In the buckling issue of pipelines,the structure is usually considered as a plane stress ring,but if there exists axial displacement constrain,the status may be closer to the status of a plane strain ring.In this paper,the elastic buckling problem of the plane-stress and plane-strain functionally graded material rings under hydrostatic pressure is theoretically investigated.It is assumed that the elastic material properties along the thickness direction continually changes according to the power law distribution.In this case,by combining the first shear deformation theory and the Kárman geometry relation and by employing the virtual displacement principle,a basic equilibrium equation of structures is deduced.Then,the buckling governing equation and the analytic solution to the structural buckling critical load are obtained by means of the eigenvalue method.Finally,the theoretical buckling perfor- mances of the structure in the plane-stress and plane-strain states are compared,and the influences of the structural radius-to-thickness ratio and the material constituent parameter on the performance are discussed.The results show that the buckling critical load of the plane-stain functionally graded material ring is slightly higher than that of the plane-stress case,and that as the inhomogeneous parameter of the material ranges from 0.1 to 10,the buckling criti- cal loads of the two kinds of rings decrease more obviously.

    CHANG Jiang-fang XU Yuan-jie CHU Xi-hua
    2016, 44(10):  70-80.  doi:10.3969/j.issn.1000-565X.2016.10.011
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    The anisotropic properties of geomaterials are significantly related to their inherent microstructures.In this paper,a modified Drucker-Prager yield criterion for transversely isotropic materials is developed by evaluating the internal friction angle with the stress state,the microstructure tensor and the material principal direction.Then,based on the Cosserat continuum theory,a consistent return mapping algorithm for the modified criterion is formulated,and a consistent tangent modulus matrix is achieved.Moreover,the codes are implemented through the user defined element subroutine (UEL) in the finite element software Abaqus,and the correctness of the pro- gram is verified by comparing the theoretical results with the relationships of the material strength to the principal direction and anisotropic degree of the material in the integration points.Finally,the influences of the principal direction and anisotropic degree of the material on the bearing capacity and the failure mode of the structure are em- phatically analyzed by numerical examples,which are then compared with the results based on the classical contin- uum theory.It is found that the above-mentioned method is effective in simulating the strain localization of trans- versely isotropic geomaterials.

    MENG Guang-wei LI Xiao-lin ZHOU Li-ming LI Feng WANG Hui
    2016, 44(10):  81-86.  doi:10.3969/j.issn.1000-565X.2016.10.012
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    Functionally graded piezoelectric material (FGPM) is an electromechanical coupling material of conti- nuous property variation.Due to the heterogeneity of the FGPM property,investigating the mechanics of this mate- rial has posed a great challenge.In this paper,an analytical model describing the electromechanical coupling of the FGPM is constructed based on the mixed extended multi-scale finite element method (MEMsFEM). In the model,the multi-scale base functions of electrical fields are set up by using the traditional multi-scale finite element method,and the multi-scale base functions of displacement fields in different directions are set up by using the ex- tended multi-scale finite element method.Moreover,the coupling terms are introduced to model the coupling a- mong the displacement fields in different directions.Since constructing multi-scale base functions helps capture the material heterogeneity effectively,it is feasible to solve the problem in a coarse grid scale,which can significantly reduce the computation amount.Finally,the proposed method is proved to be effective and efficient by numerical examples.It is thus concluded that the proposed method provides an effective approach to simulating the mechani- cal behaviors of functionally graded materials.

    LIU Run-dong MAO Jun ZHAO Meng XI Yan-hong
    2016, 44(10):  87-95.  doi:10.3969/j.issn.1000-565X.2016.10.013
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    When high-speed trains are running,the windbreak can guarantee their safety.And meanwhile,it has to suffer strong air fluctuating pressure caused by the high-speed train-induced wind.In this paper,based on the STAR-CCM + software and by taking the CRH3 high-speed train and the windbreak as the research objects,the change of the air fluctuating pressure caused by the train-induced wind during the whole process of the high-speed train passing through the windbreak area is simulated by combining the sliding mesh method and the porous medium model that can effectively reduce the amount of grids in hole plates.Then,the time history changes of the air fluc- tuating pressure with such parameters as the train speed and the terrain clearance are analyzed,and the peak and gradient of the fluctuating pressure in the position of the windbreak are put forward,thus obtaining the frequency domain characteristics of the fluctuating pressure.The results show that (1) when the high-speed train passes through the windbreak area,the alternating loads,which are positive-negative-negative-positive,form on each part of the windbreak; (2) the fluctuating pressure peak decreases in the order of the positive pressure on the head train,the negative pressure on the head train,the negative pressure on the tail train and the positive pressure on the tail train,and the fluctuating pressure gradient becomes more obvious with the increase of the train speed; (3) as the terrain clearance decreases,the fluctuating pressure increases and reaches up to a maximum value in the bottom area of the windbreak; and (4) the power spectrum density peaks of the fluctuating pressure are con- centrated below 25Hz,and the impact energy of the train-induced wind increases by nearly 100% when the train speed increases by 50km/h.

    Architecture & Civil Engineering
    CHEN Qing-jun QIU Kai-xiang TANG Xu-lin YUAN Guo-cai XIAO Min YANG Chun
    2016, 44(10):  96-103.  doi:10.3969/j.issn.1000-565X.2016.10.014
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    The typical timber ancestral halls in Canton in Lingnan area were investigated in this paper.In order to explore the mechanical properties of the hoop head tenon joints of the timber ancestral hall,one scaled model of Merbau timber frame was tested under the vertical static load while one scaled model of timber frame was tested un- der the low-cycle reversed loading.By the former test,the behaviors of the hoop head tenon joints,such as the failure mode,the mechanical characteristics and the stiffness characteristic,were obtained.By the latter test,the behaviors of the hoop head tenon joints,such as the failure mode,the hysteretic curves,the skeleton curves,the ductility,the stiffness degradation and the energy dissipation,were gained.Experimental results show that the specimen under the vertical static load fails because the bottom wood fiber of the beam breaks,while the specimen under the low low-cycleic reversed loading fails because of the splitting failure of the lateral of the beam end.In addition,under the low low-cycleic reversed loading,the hoop head tenon joints show a semi-rigid characteristic with a plump hysteretic curve,a concave and convergent stiffness curve,and a large equivalent viscous damping coefficient,which means that the specimen has a good seismic behavior.

    HAO Jian-bin MEN Yu-ming WANG Ban-qiao
    2016, 44(10):  104-109.  doi:10.3969/j.issn.1000-565X.2016.10.015
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    By model tests,the working condition of compression-type anchors in a man-made soil slope is simula- ted under the surface-loading.Then,the axial strain characteristics of the anchor bars in each row are investigated under the step-loading,and the changes of the strain with the loading time are also discussed.The results show that (1) for a man-made slope,the most dangerous stage under the surface loading appears during the load trans- ferring,and an additional load will be added to the anchors when the slope is compacted by the surface-loading; (2) under a small load,the bottom anchors in the range of the compacted soil integrally move downward under the compaction and bear no axial force,but the top and middle anchors with their grouted sections beyond the compac- ted soil are loaded with less tension that is caused by the landslide displacement; (3) under a middle load,the soil is still in the compacted process,and the axial strain distribution of each anchor along its length shows little change; and (4) under a high load,the anchorage sections of all anchors play a gradually active role in strengthe- ning the slope and jointly bear the slope sliding force until the slope failure.

    LI Xue-ping LI Dong-hong SU Cheng WEI Peng
    2016, 44(10):  110-116,124.  doi:10.3969/j.issn.1000-565X.2016.10.016
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    In this paper,two time-domain explicit expressions of the non-stationary random seismic response sensi- tivity are derived respectively based on the precise integration format and the Newmark-β integral format,and they are respectively used to analyze the sensitivity of a plane frame and a plane truss structure.Then,the effects of the integral time step on the calculation accuracy and the efficiency of the two integral formats are investigated.It is found that,when the main frequency of the structure is within the range of the main load frequency,the time-do- main explicit expression based on the precise integration has a higher efficiency with the same accuracy,but when the main frequency of the structure deviates from the main load frequency range,the time-domain explicit expres- sion based on the Newmark-β integral format achieves a higher efficiency.The research achievements can provide an effective reference for the choice of the numerical integration algorithms used in the structure optimization consi- dering the non-stationary random vibration.

    GUO Meng LIU Zhi-yuan HUANG Wei WANG Shuang-jiao YUAN Quan
    2016, 44(10):  117-124.  doi:10.3969/j.issn.1000-565X.2016.10.017
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    In order to meet the overall seismic strengthening requirements of seismic damage frame structures,a new strengthening method of embedding the RC (Reinforced Concrete)-aerated concrete block wall into the frame structure was proposed,and the feasibility of the proposed method was discussed by a model test.First,one 1∶ 2 scale concrete frame specimen was pre-damaged to a large earthquake damage state.Then,by embedding the com- posite wall into the frame structure,the reinforcement work was completed.Finally,a seismic performance test was conducted on the specimen again.According to the experimental results,the original frame and the seismic damage-reinforced frame are analyzed in terms of the failure process and the hysteresis curve characteristics,and are compared in terms of the bearing capacity,the stiffness and the deformation capacities.The results show that,as compared with the original frame,the bearing capacity of large earthquake damage frames strengthened with aer- ated concrete block composite walls is almost the same or even slightly improved,with greater equivalent lateral stiffness and energy dissipation capacity in the yield and the ultimate stages as well as with slightly worse deforma- tion capacity and energy dissipation in the destruction stage,which means that the proposed method is possibly feasible.

    Food Science & Technology
    GAO Wen-hong LIN Ping-zhou ZHONG Bi-jiang ZENG Xin-an
    2016, 44(10):  125-131.  doi:10.3969/j.issn.1000-565X.2016.10.018
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    Three kinds of water soluble soybean polysaccharides,namely,SSPS P1 ,SSPS P2 and SSPS P3 ,were extracted from soy bean dregs by using tartaric acid,sodium hexametaphosphate and sodium hydroxide.Then,the flocculation effects of the SSPS on the brewer yeast suspension with different metal cations (Al3+ 、Fe3+ 、Fe2+、Mg2+、Ca2+、K+、Na+ ),polysaccharide concentrations,pH values and temperatures were respectively in- vestigated.Moreover,the response surface experiment design was performed to optimize the flocculation condi- tions,and a corresponding mathematical regression model was constructed.Single factor research results show that (1) SSPS P1 has the best effect in flocculating the brewer yeast suspension; (2) most of the metal cations increase the flocculation effects,among which Fe3+ shows the best performance; (3) when the Fe3+ concentration reaches 0. 025mmol/L,the best flocculation effect can be achieved; (4) the flocculation effects can also be influenced by the SSPS P1 concentration and the temperature,and the effects are better at 10mg/L and 30℃; and (5) a strong alkaline environment is helpful in adopting SSPS P1 to flocculate the brewer yeast suspension.The analytical results based on the constructed model indicate that the optimal flocculating condition is a SSPS P1 mass concentration of 11. 56mg/L,a Fe3+ concentration of 0. 26mmol/L,a pH value of 9. 05 and a temperature of 30. 68℃,and the experimental value of the flocculating rate under the optimal condition is very close to the predicted one,which means that the constructed model can reflect the influence of various factors on the flocculation effect.

    ZENG Xin-an OU Yun WANG Man-sheng
    2016, 44(10):  132-136.  doi:10.3969/j.issn.1000-565X.2016.10.019
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    In the investigation,the effects of the pulsed electric field (PEF) treatment on the survival ratio and cytomembrane permeability of Salmonella Typhimurium are discussed,and the effect of the PEF treatment time on the phospholipid conformation of S. Typhimurium is also analyzed by using the Raman spectra.The results show that (1) as the energy of PEF inputs continuously,the cell viability decreases and the cytomembrane permeability increases; (2) with the increase of the PEF treatment time,the peak value ratio of the Raman spectra of S. Typhimurium phospholipid,namely I1139 /I1082 ,first increases and then decreases,and it is always higher than that without PEF treatment (P <0. 05),which indicates that the PEF treatment can increase the number of the all-trans conformation of C—C and decrease the number of the gauche conformation of C—C; and (3) as the PEF treatment time increases,I2874 /I2862 increases (P <0. 05),which means that the PEF treatment increases the lateral chain interaction of C—H and thus results in the increase of the intrachain order of phospholipid molecules and the decrease of the cytomembrane fluidity of S. Typhimurium.Therefore,it is concluded that the PEF treat- ment can cause cell damage or cell death by increasing the cytomembrane permeability and decreasing the cytomem- brane fluidity.This investigation provides a theoretical basis for the mechanism research of inactivating micro-or- ganisms with the PEF treatment.

    HU Song-qing ZHANG Ya-ping WANG Jing-jing LIU Guang-yi HUANG Yan-bo LI Lin HOU Yi
    2016, 44(10):  137-142.  doi:10.3969/j.issn.1000-565X.2016.10.020
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    By means of intrinsic fluorescence measurements,total free sulfhydryl (SH) quantitation,non-reducing and reducing SDS-PAGE analysis and AFM,the effect of pH on the forming of the N-terminal domain aggregation of high molecular weight glutenin subunits (HMW-GS) 1Dx5 (1Dx5-N) was investigated.The results show that (1) in comparison with the acidic and alkaline conditions,the maximum emission wavelength of 1Dx5-N displays a blue shift under the neutral pH condition (pH 7. 0),indicating that 1Dx5-N under the neutral pH condition has a higher degree of aggregation; (2) in comparison with the acidic and alkaline conditions,the 1Dx5-N under the neutral condition is of a lower total free sulfhydryl (SH) content with more dimers and polymers,indicating that,in the ag- gregation of 1Dx5-N,the neutral condition is more helpful and the disulfide bonds play an important role; and (3) under the neutral pH condition,the aggregation of greater particle size forms,which further proves that the neutral pH condition is superior to the acidic and alkaline conditions in terms of the aggregation of 1Dx5-N.Thus,the rationality of the flour product processing under the neutral condition is demonstrated at the molecular level.

    LIU Guo-qin WAN Wen-bo
    2016, 44(10):  143-150.  doi:10.3969/j.issn.1000-565X.2016.10.021
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    Ternary curcumin-organogels were prepared based on corn oil and by using sitosterol + letithin,cera- mide,ethyecellulose as thestructurants.Then,the effects of the structurants on the macroscopic properties (the rheological behaviors,the solid fat content,etc) and the microscopic properties (the microstructures,the crys- talline structure,etc) of ternary organogels were discussed,and the corresponding loading capacities were also evaluated.Experimental results show that (1) the structures of sitosterol + letithin-organogels and ceramide- organogels are similar and are both fibrous crystal structure,and the former exhibits a tighter network with higher encapsulation efficiency (EE) and loading capacity (LC),which are respectively (3. 14 ± 0. 10) mg/g and (62. 78 ±2. 01)%; (2) however,the structure of ethyecellulose-organogelsis totally different from the above two structures,and it is granular with a smaller crystal and relatively loose network; and (3) because of higher prepa- ration temperature.ethyecellulose-organogels show the highest load level,specifically,LC and EE are respectively (4. 810 ±0. 174)mg/g and (96. 19 ±3. 48)%. The above results indicate that the structurants significantly affect the properties,microstructures and loading capacity of organogels.

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