Abstract:To establish a mechanical model of long bone diaphysis based on its physiological properties,in which the ef-fects of periosteum and the marrow on the diaphysis were included.The constitutive equation of the diaphysis in the longitudinal direction was obtained,which provided a basic foundation for further research on the loading properties of long bone.

Abstract:In order to study the effect of blood flow shear stress on endothelial cells(ECs),we established a simple parallel flow chamber system,which can produce048dyn/cm 2 steady laminar flow shear stress.Using this system,the effect of shear stress on F-actin,G-actin and the morphology of ECs were studied.The results shows under12,24,48dyn/cm 2 shear stress for12h the stress fiber (F-actin)which aligned originally in its own long axis gradually become along the direction of blood flow.The contents of F-actin increased and the contents of G-actin decreased.The morphology of ECs have no changes.It demonstrated that the simple parallel flow cham-ber system is useful in assessing the effects of shear stress on ECs .

Abstract:The influence of the explosive blast with different pressures on the permeability of the pulmonary microvascular endothelial cells monolayer(PMECM)was observed.The results showed that the explosive blast about 100kPa might increase the permeability of PMECM.The explosive blast lower than100kPa could mainly cause the ex-panding of the gap between endothelial cells while that higher than100kPa might result in the exfoliation of cells monolayer.

Abstract:Objective:To investigate the effects of body mass index(BMI)on speed of sound(SOS)of the tibia in young and postmenopausal women.Methods:SOS were measured by bone quantitative ultrasound(QUS)apparatus in399young and589postmenopausal women,who were devided into three groups(low body weight ,normal weight and overweight )according to their BMI.Result:There was no significant difference in SOS among three groups(F=0.2,P=0.801)and no significant correlation between BMI and SOS in young women(r=0.054,P=0.287).Signifi-cant positive correlation was found between BMI and SOS in postmenopausal women(r=0.115,P=0.006),and the SOS of overweight group was significantly higher than that of the low body weight group and normal weight group(F=4.2,P=0.016).The incidence of osteoporosis in overweight group and normal weight group was signifi-cantly lower than in low body weight group (P<0.001).Conclusion:BMI has no significant effect on tibia strength in young women,but higher BMI can reduce the rate of loss of the tibia strength in postmenopausal women.

Abstract:To investigate the stress changes of lumbar vertebrae internal structure in torsion by using a finite element mod-el.The three-dimensional finite element model of an intact L 4 -L 5 lumbar motion segment was established and loaded under different force of torsion.The results showed that the rotation degrees of L 4 -L 5 segment,average axial effective stress of intervertebral disc,pore pressure,fiber stress and strain and facet load increased with the increase of torsion.

Abstract:Based on CT picture,the geometrical dimensions of humerus were obtained.A three-dimensional finite element model was established on the basis of three-dimensional reconstruction.At three different angles30°,45°,90°,with fracture,the force along the axis of the humerus was calculated by using ANSYS5.6and stress distribution was gained.We acquire some information according to the results.The information may offer a theoretical foun-dation for the treatment of humeral fracture.

Abstract:The anatomy reports indicated that atherosclerotic lesions were located on the inner wall,or both inner and out-er walls of the sinus of the carotid bifurcation in the many cases.This phenomenon was not explained by the hypothesis about the low wall shear stress in the traditional Y-AHCB model.In this paper,in the modified model of″average human carotid bi furcation(AHCB)″the three-dimension field in carotid sinus under steady flow conditions was studied using flow visualization techniques and laser-Doppler anemometer(LDA).The effects of the shape of branches on the flow separation and were observed.A new separation zone along inner wall of sinus was found.It can be used to explain plaque distribution on the inner wall of sinus.The modified model was proved to be a more rational model for hemodynamics and atheosclerosis study in human carotid bifurcation.

Abstract:In this study,according to the changes of curvature of the outline and the partial shape center location of the irregular object,a mathematical method is set up to build up the3D model of the irregular object,which is a solid foundation to analyze and design the object.This method,which has successfully built up mandible3D model,one of the most complex parts of the body,and made mechanics analysis,has been applied in the clinical engineering and also gives some idea to analyze and design complex parts in other fields.

Abstract:To observe the normal hemorheological characteristics of the nude mice,hamsters and Sprague-Dawley(SD)rats.Methods:The blood viscosity values of the nude mice,hamsters and SD rats were tested simultaneously by means of the cone and plate viscometer and Cosson Viscosity(CV),Cosson yield stress(CY)in the blood among them were obtained by unitary linearly regression.Results:The whole blood viscosity at high shear rate,hemot-ocrit,erythrocyte index of rigidity among three animals were nearly the same,there was a little higher in the nude rat group and no statistically significant difference among three groups.Significant difference existed in the values of whole blood viscosity at low shear rate,plasma viscosity and aggregation index of erythrocyte(p<0.01).The values of the SD rats were the highest among three groups.In the CV value there was no statistically sig-nificant difference among three groups(P>0.05).Significant difference was found in the CY value(p<0.01).Con-clusion:The erythrocyte deformability properties is nearly the same among the three animals.But in the charac-ter of the erythrocyte aggregation which involved many other factors outside the blood cells,there existed signifi-cant difference among the three animals.

Abstract:To evaluation the biomemory characteristics of NiTI-patellar concentrator(NiTi-PC)in the treatment of patellar fracture and its results in clinical application.Methods:Six fresh adult specimen of knee were fixed with NiTi-PC and AO tensile band,The biomechanical properties of two kinds of internal fixation were tested and clinical results were evaluated.Result:No significant difference was found in the biomechanical properties between two groups(P>0.05).Conclusion:NiTi-PC has a good biomechanical characteristics and good results in the treatment of patellar fracture.

Abstract:Objective:The biomechanical study of three kinds of internal fixations was performed in order to get the best treatment of femoral shaft fracture in child.Methods Three triangular needles,cloverleaf nails and plate were used respectively as internal fixators in10femoral specimens from child corpses and subjected to biomechanical tests.Results1.Three point bendings①Under Anterior loading,the rigidity of triangular needle was medium,its remnant deformation was smallest.②Lateral loading,the rigidity of triangular needle was smallest,its rem-nant deformation was medium.③Under Lateral downward loading(40mm),the remnant deformation of triangular needle was smallest.2.Torsive tests:①The rigidity and the remnant angle of the triangular needle were medi-um when it was rotated externally and internally.②The remnant angle of the triangular needle was smallest when it was rotated externally15°.Conclusion The biomechanical experiments of three point bending and tor-sive tests proved that the triangular needle had good elasticity,best restorable function and strongest anti-rota-tion force.The use of three triangular needles of internal fixation for the treatment of child femoral shaft frac-ture was evidently better than those of cloverleaf nail and bone fracture plate.

Abstract:Three-dimensional stress freezing method of photoelasticity was used to analyze internal stress distribution on the alveolar bone of the abutment with a complete fixed bridge under three kinds of occlusal loads.A three-dimen-sional model was used to represent a missing mandibular first permanent molar.The ratio of the model and prototype was1.The results showed that the direction of occlusal loads exerted an direct influence on the mag-ni tude of the stress of the alveolar bone.The horizontal static load might lead to stress concentration in the alveolar crest while the vertical load could result in the greatest stress in the corresponding alveolar crest and apex of a single root..The stress distribution of supporting bone around molar root was most equal,regardless of loading form.The molar is an ideal abutment tooth for a fixed bridge.

Abstract:To determine the mechanical properties(stiffness)and compression force of a new design of point contact plate,with the ability of dynamic compression for reducing the gap at the fracture site and enhancing the stability.Methods:A device wasused compare the compression force of point contact-dynamic compression plate(PC-DCP)with that of dynamic compression plate(DCP)when a cortical screw was placed at compression position.In20paired fresh cadaveric sheep tibiae,mid-shaft transverse osteotomies were created and fixed with PC-DCPs and DCPs.In10pairs,compression force was applied at the fracture sites.In the other10paires,there was a3-mm gap between the fracture sites.Four point bending and torsion tests were conducted to determine the bend-ing and torsion stiffness.Results:there were no statistically significant differences in compression force between the DCPs and PC-DCPs (p>0.05).Whether there was a bone gap or not,no significant differences in bending and torsion stiffness were seen.between the two experimental plates(p>0.05).Conclusion:The PC-DCP can ap-ply a comparable compression force between the fracture gap.Mechanically,the PC-DCP plate has adequate sta-bility in clinical application.