Table of Content

25 November 2014, Volume 42 Issue 11

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Mechanical Engineering

Research of intelligent wire feeding machine for underwater welding robot

Wang Zhen-min Feng Rui-jie Feng Yun-liang Huang Shi-sheng

2014, 42(11):  1-6.  doi:10.3969/j.issn.1000-565X.2014.11.001

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Aiming at the characteristics of underwater robotic welding process,a digital and intelligent underwater wire feeder is developed for the underwater gas metal arc welding.First,a digital control system is constructed with the DSC microcontroller STM32F405RGT6 based on the ARM Cortex^TM - M4 architecture as the control core.Then,a PWM- controlled half- bridge reversible chopper circuit based on the negative feedback of armature voltage is de- signed as the drive circuit,so as to compensate the fluctuation of the wire feeding speed caused by the variation of load torque.Finally,a welding wire detection module based on an eddy current proximity switch is developed,and thus the non- contact and real- time monitoring on the welding wire state is realized. Experimental results indicate that (1) the developed underwater wire feeder can monitor the welding wire state reliably,and feed wire uniformly and stably even when the state of wire feeding tube changes; and (2) the changing rate of wire feeding speed is within ±3.5%,which meets the national standard well.

Singularity Configuration Analysis and Avoidance of a New Type of Spatial 5- DOF Parallel Mechanism

Chen Bing-fa Ding Wang-sheng Ding Li-ping Chen Wen-liang

2014, 42(11):  7-13.  doi:10.3969/j.issn.1000-565X.2014.11.002

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In the investigation,a new type of spatial 5- DOF parallel mechanism is constructed by constraining branched chains,and is used to realize the three translational DOF and two rotational DOF of a moving platform.First,the DOFs of the mechanism are analyzed by means of the screw theory,and the constraint and movement sub- matrices of the mechanism are deduced.On this basis,a complete Jacobin matrix of the mechanism is esta- blished. Then,the singular conditions of the mechanism are analyzed on the basis of the Jacobin matrix,and two methods to avoid the singularity configuration of the mechanism are proposed by choosing the working range of the moving platform or by changing the mechanism dimensions.Finally,the correctness and effectiveness of the pro- posed method is verified by a numerical example.

Folding Criterion of Die Block Forging of 5CrNiMo During Stretching

Zhao Xue-zhi Fan Yan-bo Xia Qin-xiang Lü Ming- ke

2014, 42(11):  14-18,24.  doi:10.3969/j.issn.1000-565X.2014.11.003

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In order to reveal the effects of reduction and feed amount on the surface quality of forgings during the stretching,and to establish a criterion judging the occurrence of stretching folding,a stretching model of 5CrNiMo die block forgings is constructed by means of the FEM software DEFORM- 3D,and the effects of the reduction- to- feed amount ratio (namely the M value) on the maximum folding corner and the folding depth are discussed.It is found that the stretching folding occurs at a critical M interval of 0.8 ～1.0.On this basis,a criterion to judge the occurrence of folding during the stretching is established,that is,the folding of forging surfaces can be avoided when M is less than the range of 0.8 ～1.0,while the folding occurs when M is within or exceeds the range of 0.8 ～1.0.

Design of Imaging System for PCTP ITO Pattern Inspection by Using Line- Scan CCD

Jiang Chang-cheng Quan Yan-ming Peng Yan-hua

2014, 42(11):  19-24.  doi:10.3969/j.issn.1000-565X.2014.11.004

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In order to acquire high- contrast images in the defect inspection of the PCTP (Projected Capacitive Tou- ch Panel) ITO pattern by using the line- scan CCD,a coaxial illumination and imaging system based on the maxi- mum difference value between superposed reflection coefficients is designed and established according to the bright- field reflection illumination principle.Then,the illumination and imaging patterns are analyzed by taking into ac- count the optical properties of the glass substrate,the PCTP ITO material as well as the geometrical structure of the ITO pattern,and the influence factors of the imaging contrast between the ITO film and the glass substrate are ana- lyzed by considering the multi- layered composite structure of the ITO pattern.Finally,at a higher scan rate which can cause a higher productivity,the imaging parameters of the high- contrast images of the ITO pattern and the glass substrate are determined by comparing a series of images taken at different illumination intensities.Experiment re- sults indicate that,when the ITO substrate scans at a rate of 130mm/s with an inspection precision of 10μm and a light intensity of 190,image gray histograms have two apparent peaks,which helps to inspect the defects of ITO patterns.

Effect of Ethylene Glycol on Lapping of Sapphire Wafer by Using Fixed Abrasive Pad

Wang Jian-bin Zhu Yong-wei Ju Zhi-lan Xu Jun Zuo Dun-wen

2014, 42(11):  25-30,39.  doi:10.3969/j.issn.1000-565X.2014.11.005

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The chemical additives in lapping slurry play a vital role in the efficient ultra- smooth machining of sap- phire wafer.In the investigation,the lapping experiment of sapphire wafer was performed by using a fixed abrasive pad,and the effects of the ethylene glycol concentration in lapping slurry on the material removal rate (MRR) and surface morphology of sapphire wafer were discussed.Then,the micro/nano- indentation technique and the photoe- lectron spectroscopy (XPS) were employed to analyze the physical and chemical properties of lapped wafer surface.The results indicate that (1) when the lapping slurry contains 5% ethylene glycol,the depth of surface- modified layer on the lapped wafer surface is about 3.90 nm,and is superior to that in the deionized water,which is 1.04 nm; and (2) higher ethylene glycol content can promote the surface- modified layer to form,which helps to improve the lapping efficiency and enhance the surface quality.

Sensor Fault Detection and Isolation for an Electro- Hydraulic Servo System Based on Robust Observer

Xu Qiao-ning Yu Feng Zhou Hua Yang Hua-yong

2014, 42(11):  31-39.  doi:10.3969/j.issn.1000-565X.2014.11.006

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In the electro- hydraulic servo system,extra sensors are often added for fault detection and isolation (FDI),but the sensor fault can cause a false alarm.The electro- hydraulic servo system itself is a typical nonlinear system and is often subjected to time- varying and unknown disturbances,which brings about great challenges to the sensor FDI.In order to solve these problems,a FDI scheme based on a nonlinear robust observer is proposed.In this scheme,the robust observer is used to handle the system nonlinearity as well as unknown disturbances and a linear matrix inequality method is adopted to facilitate the observer design.For the sensor fault isolation,a batch of robust observers is designed and some logic rules are made.Then,the proposed FDI scheme is verified by simula- tions and experiments,and an adaptive threshold is designed to make decision according to the characteristics of ex- perimental data.Both simulation and experimental results show that the proposed FDI scheme is effective.

Automotive Engineering

Control Strategy of Uniaxial Decoupled Hybrid Braking System and its Test Verification

Chu Liang Cai Jian- wei Fu Zi- cheng Zhang Yong- sheng Yao Liang Wei Wen- ruo

2014, 42(11):  40-49.  doi:10.3969/j.issn.1000-565X.2014.11.007

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The uniaxial decoupled braking energy recovery system based on the traditional hydraulic unit of ESC has been developed by Jilin University.Aiming at this system,this paper develops a control strategy of fixed partition coefficients to perform the coordinated control of electrical regenerative braking and hydraulic braking.Then,brake energy recovery control algorithms are integrated into a brake controller unit,and the control strategy is made to conduct a vehicle test.The results show that (1) when the initial speed is 60 km/h,the braking energy recovery rates are respectively 24.84%,17.38% and 10.28% for the coordination braking and the superposition braking with the desired motor torques of 80N · m and 50N · m,and (2) the vehicle deceleration and the brake pedal can be steady in the coordination braking process and the drivers has no feeling that the braking has become soft.The above results indicate that the proposed control strategy can improve the energy recovery rate and ensure that the brake pedal feeling is consistent with the traditional one.

Longitudinal Force Analysis of Tire Based on a Corrected Tire Brush Model

Zhao You- qun Li Bo Zang Li- guo Zhang Ming- jie Chen Yue- qiao

2014, 42(11):  50-54,91.  doi:10.3969/j.issn.1000-565X.2014.11.008

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In the investigation,by simplifying the tire structure,a corrected tire brush model is constructed and a longitudinal force expression is set up.Then,by analyzing the interaction between tire and ground,the kinetic and static friction ellipses are established to solve the longitudinal forces from attachment and slip regions,and the rela- tionship between the two longitudinal forces is discussed.According to the stiffness difference of tire tread and shoulder,the longitudinal forces of the tread and the shoulder are solved under the influence of stiffness on contact patch length being considered.It is found that the corrected tire brush model accords well with the magic formula and the experimental results when the slip rate is between 0.0 ～0.2.Besides,the proposed method helps to opti- mize the design of tire.

A Study on Nondestructive Testing Technology for Recycling of Re- Usable Automotive Parts

Pang Lin- hua Wen Gui- lin

2014, 42(11):  55-62.  doi:10.3969/j.issn.1000-565X.2014.11.009

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Recycling of qualified or re- useable automotive parts is an inevitable trend for the development of auto- motive recycling market and dismantling industry,and is a practical requirement for the development of resource- saving society.The precondition of the recycling is that the testing technologies are advanced enough to ensure the quality of re- usable parts.The nondestructive testing technology has become an important means of quality control.In this paper,the nondestructive testing technology for reusing automotive parts is taken into account.Five nondes- tructive testing technologies,namely,X- ray testing,ultrasonic testing,magnetic particle testing,eddy current tes- ting and permeability testing,are discussed and the application scopes and characteristics of several new nondes- tructive testing technologies are generalized.Furthermore,this paper points out that the trends of the nondestructive testing technology for the recycling of re- useable automotive parts are to make traditional detection methods more au- tomatic and intelligent,to design more reasonable test evaluation system,to integrate multiple detection means and to exploit new detection technologies.The final conclusion can provide guidance for the in- depth research of the nondestructive testing technology for the recycling of re- useable automotive parts.

Vehicle Stability Criterion Based on Phase Plane Method

Liu Fei Xiong Lu Deng Lü-hua Feng Yuan Wu Xiao-peng

2014, 42(11):  63-70.  doi:10.3969/j.issn.1000-565X.2014.11.010

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In this paper,the vehicle stability is analyzed on the basis of phase plane method,and a vehicle stability criterion is determined according to the change laws of the phase plane.First,a nonlinear single- track vehicle mo- del is constructed by using vehicle test data.On this basis,a sideslip angle- sideslip angular velocity phase plane is established as the stability criterion.Then,by analyzing the shortcomings of the existing phase stability region divi- sion methods,a new method using five characteristic values to determine the diamond stability region is proposed,specifically,the diamond region moving with the equilibrium point is selected as the stability region according to the change laws of the phase plane.Moreover,a dataset of the characteristic values of the stability region under full condition is built by a large number of simulations and the change laws of both the characteristic values and the sta- bility region are discussed.Finally,the results obtained by the stability criterion based on phase plane method are used to determine the introduction of the stability algorithm.Simulation results show that the proposed stability cri- terion can provide a basis for stability control algorithms and improve vehicle stability.

Path Tracking for Parallel Parking Based on Linear Extended State Observer

Wang Jian Zhao You- qun Ji Xue- wu Liu Ya- hui Zang Li- guo

2014, 42(11):  70-77.  doi:10.3969/j.issn.1000-565X.2014.11.011

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In order to eliminate the external disturbance and remove the influence of the uncertainty of the steering system kinematics model,a vehicle kinematics model of parallel parking system is constructed and a third- order li- near extended state observer is designed.The observer takes the external disturbance and the model uncertainty for a total disturbance to observe and compensate without building the accurate mathematical model of controlled ob- jects.Based on this observer,a path- tracking controller is established for parallel parking and its control perfor- mance is verified by a simulation and a real vehicle test.Simulation results show that the proposed path- tracking controller shows a better performance and a stronger ability to resist the external disturbance in comparison with those of the traditional PID controller.The real vehicle test results show that the proposed path- tracking controller can control vehicles to finish parallel parking tasks precisely with a maximum error of only 0.111m.

Design and Characteristics of Dual Mass Flywheel with Magneto- Rheological Fluid

Mao Yang Chen Zhi- yong Shi Wen- ku

2014, 42(11):  78-84.  doi:10.3969/j.issn.1000-565X.2014.11.012

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The torsional damper of dual mass flywheel (DMF) should be different under different conditions of ve- hicles.Aiming at the above issue,the MRF is applied to the DMF by taking into account the rheological behavior of the magneto- rheological fluid (MRF) in a magnetic field.Then,by designing a two- stage stiffness curve,arc spring parameters,magnetic circuits and a damping torque in working clearance,a magneto- rheological- fluid dual mass flywheel (MRF- DMF) controlling the torsional damper through the exciting coil current is designed and made,and its service performance is verified by a static characteristic test.Finally,an AMESim model is constructed and verified by a bench test.The results indicate that the semi- active control of the torsional damper of MRF- DMF can be realized by adjusting the exciting coil current.

Architecture & Civil Engineering

Sound Absorption Coefficient Measurement of 1∶10 Acoustic Scale Model Material of Auditorium

Sun Hai- tao Zhao Yue- zhe Wu Shuo- xian

2014, 42(11):  85-91.  doi:10.3969/j.issn.1000-565X.2014.11.013

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For the architectural acoustic scale model of a scale ratio of n,the model materials at the frequency of nf should have the same sound absorption properties as the corresponding full- scale building materials at the frequency of f have,and the similarity of the sound absorption coefficient of the model material to that of the corresponding full- scale building material directly affects the precision of the scale model experiment.In the investigation,a 1:10 scale reverberation chamber on the basis of the architectural acoustic reverberation chamber of South China University of Technology was built and verified by experiments,and the sound absorption coefficients of various sound absorption materials and seats were measured in this scale reverberation chamber.The results show that (1) the high- density polyester fiber board has a higher sound absorption coefficient due to its more compact fiber structure and smaller pore; and (2) the 1:10 scale seats made from the polyester fiber board have similar sound absorption characteristic to those of the real seats in theatre and concert hall,so the scale seats can be used to accurately simulate the sound ab- sorption of the real seats>These results provide a reference for selecting the model material in the 1:10 architectural acoustic scale model experiment and are beneficial to the measurement of the acoustical scale model of auditorium.

Seismic Behavior of Precast Shear Wall with Rectangular Spiral Stirrups- Constraint Grouted Corrugated Pipe Connection

Liu Jia- bin Chen Yun- gang Guo Zheng- xing Yuan Fu

2014, 42(11):  92-98.  doi:10.3969/j.issn.1000-565X.2014.11.014

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In order to comprehensively evaluate the seismic behavior of the precast concrete shear wall with rectan- gular spiral stirrups- constraint grouted corrugated pipe connected to horizontal joints,the full- scale specimens of the shear wall was tested and compared with the cast- in- place specimens through a low- cycle loading experiment.The results show that the (1) the full- scale specimens follow the same failure pattern as the cast- in- place specimens do; (2) due to the existence of horizontal joints,the whole loading processes of the two kinds of specimens are diffe- rent; (3) the hysteresis curves of the two kinds of specimens are both full with similar skeleton curves,and the energy dissipation capacities are also similar; (4) the two kinds of specimens are of the ultimate displacement an- gles of 1/49 and 1/45 respectively,and the displacement ductility factors are both 4.0,which can meet the ductili- ty requirements; (5) the load capacities of the full- scale specimens at different stages are lower than that of the cast- in- place specimens; and (6) precast concrete shear wall with reasonable horizontal joints is of the ductility,load capacity and seismic energy dissipation capacity similar to those of the cast- in- place specimens.

A Simplified Formula of Effective Flange Width of RC Frame Considering Slab Reinforcement Participation

Wang Su- guo

2014, 42(11):  99-105,120.  doi:10.3969/j.issn.1000-565X.2014.11.015

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The current theoretical calculation formula of effective flange width of RC frame considering slab rein- forcement participation is too complicated and inconvenient for practical application.In order to solve these prob- lems,by taking into account two main factors influencing effective flange width,namely,axial compression ratio and joint type,RC frames with different axial compression ratios are designed and a numerical regression analysis on the distribution of the effective flange width with different joint types is conducted.Thus,a simplified formula of effective flange width is obtained,which is convenient for practical application.Then,some issues for improving designs are suggested for the purpose of No Collapsing in the Strong Earthquake,and the suggestions and the sim- plified formulas are verified by an example.The results show that (1) the simplified formula is simple and easy to handle,so it is feasible in actual designs; and (2) the suggestions help to realize the purpose of No Collapsing in the Strong Earthquake better.

Strain Rate Sensitivity and Constitutive Relation of Mechanical Properties of CA Mortar

Zhang Sheng Fu Qiang Zhou Xi- ling Long Guang- cheng Xie You- jun

2014, 42(11):  106-112.  doi:10.3969/j.issn.1000-565X.2014.11.016

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In order to investigate the strain rate sensitivity of the mechanical properties of cement and asphalt mortar (CA mortar),the stress- strain compressive experiment of CA mortar at different strain rates was performed by means of a microcomputer- controlling electronic universal testing machine.The results show that the mechanical properties of CA mortar increase with the strain rate,and the strain rate sensitivities are attributed to the limit of the crack propagation velocity,the inertial effect of the lateral deformation and the horizontal restraint of the asphalt network structure.Furthermore,a constitutive relation of strain rates is established.The constitutive relation can accurately stimulate the peak strength and elastic modulus of CA mortar,and the multiple correlation coefficients of the fitting and experimental results in the whole deformation process are both greater than 0.93.It is also found from the analysis of the sensitivity of constitutive relation that,the higher the strain rate is,the lower the toughness and strain rate sensitivity of CA mortar will be.

Mechanical Properties of Stirrups Confinement Concrete- Filled Round- Ended Steel Tubular Stub Short Columns Under Axial Compression

Fu Lei Ding Fa- xing Gu Li- xiong Gong Yong- zhi

2014, 42(11):  113-120.  doi:10.3969/j.issn.1000-565X.2014.11.017

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In order to improve the mechanical properties of confinement concrete- filled round- ended steel tubular (CFRT) stub columns,this paper adopts the way of welding stirrups to enhance the constraint effect on core con- crete.Then,the ABAQUS software is employed to analyze the finite element parameters of the 3D solid of stirrups confinement concrete- filled round- ended steel tubular (SCFRT) stub columns in four constraint ways,and the way of bidirectional butt joint stirrups is found to be the best.Finally,two sets of CFRT stub columns and two sets of SCFRT stub columns are investigated by experiments.It is found that the experimental results accord well with the simulation ones,which demonstrates that the way of bidirectional butt joint stirrups is rational.

Seismic Behaviors of Solid- Web Steel- Reinforced- Concrete Cross- Shaped Columns

Zhang Bo Fang Lin Jin Guo- fang Li Kai- wen Wang Zhi- liang

2014, 42(11):  121-128.  doi:10.3969/j.issn.1000-565X.2014.11.018

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In order to investigate the seismic behaviors of solid- web steel- reinforced- concrete (SSRC) cross- shaped columns,four column specimens with various axial compression ratios,steel ratios and loading directions were test- ed by low- cycle reversed loading experiments,and the crack,deformation,failure characteristics of these columns were recorded.Then,the load- displacement hysteretic curves and skeleton curves of the four columns were ob- tained,and their mechanical properties,namely,stiffness and strength degradation,displacement ductility and energy dissipation capacity,were analyzed.Finally,according to the experimental results,the effects of axial com- pression ratios,steel ratios and loading directions on the seismic behaviors of SSRC cross- shaped columns were dis- cussed.The results indicate that (1) the failure mode of the specimens with large shear span ratio is a bending fai- lure; and (2) SSRC cross- shaped columns have favorable ductility,plastic deformation capacity and energy dissi- pation capacity.In addition,as compared with lattice- style steel reinforced concrete (LSRC) cross- shaped co- lumns,SSRC cross- shaped columns show better seismic behavior.

Biological Engineering

Peanut Meal Fermentation by Bacillus subtilis BS H001 and Corresponding Product Characteristics

Liu Dong- mei Chen Hao Hu Xiao- hui Wu Hui Li Li

2014, 42(11):  129-135,142.  doi:10.3969/j.issn.1000-565X.2014.11.019

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In order to improve the amino acid balance in peanut meal (PNM) and to reduce peanut protein aller- gens,Bacillus subtilis BS H001 is used for peanut meal fermentation and the fermentation conditions are optimized.Then,some characteristics of fermented PNM (FPNM) were analyzed.Orthogonal test results show that (1) the optimal conditions of peanut meal fermentation by using Bacillus subtilis BS H001 are a water content of peanut meal of 52%,a fermentation time of 44h,a stirring interval time of 8h,a sterilization time of 45min and an ammonium sulfate content of 4.0%; (2) under such conditions,the total protein content of FPNM reaches 56.20%,which is 23.49% higher than that of PNM,and the contents of non- essential amino acids,essential amino acids and total amino acids in FPNM are respectively 4.92%,43.97% and 16.49% higher than those of PNM.SDS- PAGE elec- trophoresis shows that,three kinds of protein macromolecules in optimized groups 9,13,15,16 of FPNM,which are of the molecule masses of 63,48 and 41ku respectively,are all degraded.The above- mentioned results demon- strate that the peanut meal fermented by Bacillus subtilis BS H001 can be used as a high protein source for animals.

Growth Characteristics and Carbon Monoxide Fermentation Performance of Clostridium autoethanogenum

Xu Hui- juan Liang Cui- yi Xu Jing- liang Guo Ying Zhang Yu Zhuang Xin- shu Yuan Zhen- hong

2014, 42(11):  136-142.  doi:10.3969/j.issn.1000-565X.2014.11.020

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In order to develop the new technology of ethanol production from synthesis gas fermentation,the growth characteristics and carbon monoxide (CO) fermentation performance of C.autoethanogenum were investigated.The effects of different carbon sources on the growth of C.autoethanogenum were analyzed and the results show that xy- lose is the optimal substrate.After the growth medium being modified,the cell density of C.autoethanogenum in- creased by more than 2 times,and the metabolic products were mostly acetic acid with a small amount of ethanol.Moreover,the CO fermentation performance of C.autoethanogenum was studied in 1L gas sampling bags.After twice CO fermentation with C.autoethanogenum in the fermentation medium containing 1.0g/L yeast extract,an ethanol concentration of 3.464g/L was achieved,and the yield of ethanol from CO reached 51.7%.The investigation re- sults also indicate that the hydrolysate of bagasse treated with hot liquid water at 180℃ in a 4MPa N 2 atmosphere for 20min can be utilized to culture C.autoethanogenum,and the corresponding ethanol concentration and ethanol yield from CO can reach 3.13g/L and 46.9%,respectively after only once CO fermentation,which are similar to the results of the twice CO fermentation but with much less culture time.

Directional Osteogenic Differentiation of hMSCs and its Biocompatibility with PLGA/TCP

Wang Fei Wang Yan Cheng Lü- sha Xie Mu- yuan Zhang Li- jun Liang Shi- zhong

2014, 42(11):  143-148.  doi:10.3969/j.issn.1000-565X.2014.11.021

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In order to verify the directional osteogenic differentiation of human mesenchymal stem cells (hMSCs),the corresponding experiments were conducted with the hMSCs cultured in the osteogenic differentiation medium as the osteogenic differentiation group and those in the complete medium as a control group.Von Kassa experiment shows that hMSCs has a good osteogenic differentiation ability with obvious calcium nodules.Alkaline phosphatase (ALP) test demonstrates that the ALP activity of the osteogenic differentiation group is higher than that of the con- trol group (P ＜0.01),and reaches a peak in twelve days and then enters into a plateau phase.In order to verify the biocompatibility of hMSCs with poly lactide- co- glycolide (PLGA) /TCP,the corresponding analyses are made with the hMSCs cultured in PLGA/TCP as the 3D culture group and those on plate as the 2D control group.SEM results show that adhesion,proliferation and osteogenic differentiation of hMSCs occur in PLGA/TCP.MTT test in- dicates that the cell proliferation rate of the 3D culture group in five and seven days (P ＜0.01) is obviously higher than those of the 2D control group.ALP test also demonstrates that the osteogenic differentiation of the 3D culture group in three,five and seven days (P ＜0.05) are higher than those of the 2D control group,which indicates that PLGA/TCP possesses good cellular biocompatibility with hMSCs and they have a potential to produce tissue engi- neering bones.