Abstract:The strength and decay rate of biodegradable fixation device can be monitored and improved by mean of in vitro degradation tests. However, from literature review, it is found that the testing procedure and controlled degradation environment applied in various vitro tests are not the same. Therefore, the purpose of this research is to establish an in vitro degradation system by monitoring the degradation system of mechanical strength of a biodegradable bone screw. Conditions set for In vitro degradation and mechanical tests refer to ASTM F1635 and relevant papers. The sample screws, offered by Industrial Technology Research Institude, are made of two different materials, ie, Poly-L-lactic(PLLA) acid and the copolymer of Poly-L-lactide and Poly-glycolide(PLGA). They were put in several containers and immersed in isotonic PBS(pH=7.4±0.2, 0.15M NaCl). The temperature of buffer solution was maintained at 37±20℃ by a shake bath. Both of the shear and three points bending tests were carries o...更多ut to monitor the decay of the mechanical strength of the screws. The resulting mechanical strength reported here in is an average of 5 samples. The present results indicate that the strength of PLLA screws decreased significantly among week 6 to week 7 and PLGA screws lost almost all of its strength in about 4 week. The in vitro degradation system developed here in could be applied to help evaluating the performance of a biodegradable screw. 还原

Abstract:we have developed two colonizable bone cements :the first is a partially resorbable bisphenol-a-glycidyl methacrylate (Bis-GMA)-based cement(PRC) and the second is a calcium phosphate cement (CPC).PRC is composed of aluminous silanized ceramic and particles of a bioresorbable polymer embedded in a matrix of Bis-GMA.CPC consisted of tricalcium phosphate, monocalcium phosphate monohydrate ,dicalcium phosphate dihydtrat ,and xanthane.Both cements were implanted into cavities drilled in rabbit femoral and tibital condyles .After 2,4 ,12,and 24 weeks of implantation ,histological observations and biomechanical tests were performed .With CPC, a progressive osteointegration with a concomitant biodegradation in the presence of macrophages were observed,The mechanical study revealed a decrease of the compressive strength unitil the 4th week,followed by a concomitant biodegradation in the elastic modulus with time .Moreover.by week 4, the histological study showed that the new bone was in direct contact with CPC margins .No inflammation was observed during the observation period. Strength was higher than that of cancellous bone and CPC(P<0.05) ar all observation periods.Its elastic modulus was greater than that of cancellous bone and CPC until the 4th week ,then fell under the values of the cancellous bone,(Bone 25:41s;1999)

Abstract:Purpose: To investigate the compliance change of femoral arteries and veins in rabbit with different axis stretch ratio, evaluated the particular reference to the option of vascular repair. Methods: A mechanical analysis including stress-strain experiment and axis stretch ratio measurement was undertaken to evaluated the compliance change of femoral arteries and veins in rabbit with different axis stretch ratio. Results: The compliance is related to the pressure and the axis stretch ratio. In the artery pressure, the section area decreased 40% with axis stretch ratio of 1.9 than axis stretch ratio of 1.58 of femoral artery in rabbit, the same as that of vein. Conclusion: When the pressure was 1.19g on anastomoses, the compliance of femoral arteries was equal to that of veins in atrerial pressure. And the inner diameter of femoral arteries decreased with the axis stretch ratio increasing. It suggested to repair the injuried vessel according to the biomechanical effect.

Abstract:The study of anti-protruding properties of dura and substitutes is important to reconstnlction of skull defecfs. The parameters of anti-protruding properties of dura and substitutes are introduced on the basis of constant creep solution of the dural deflection under the constant intracranial pressure . Dura and Substitutes are arranged in order to the parameters: the fresh human dura is the best anti-protruding material,the lyophilized human dura is the best substitute, and artificial membrane of bovine cardiac valve, silicone rubber and terylene are unsuited to anti-protrudig materials. The measurements show that dura is isotropy approximately, but temporalis myofascia and pericranium is anisotropy.

Abstract:A mathematical model was proposed for the studying of the time-dependent blood flows among myocardium layers. There were three classical myocardial vascular nets in each part and each net was represented with a branch of time-dependent nonlinear resistance and compliance. Experimentally measured aortic pressure and left ventricular pressure from six male dogs were taken as input data for emulation. The results show that the blood flows among myocardium predicted with the model were increased obviously with augment of the perfusing pressure by EECP．

Abstract:in this paper , the input impedance of a pulsative flow through a vessel with mild stenosis amplitude radically was investigated .The calculate of arteria femoralis of dog showed no matter which kind of stenosis parameters change ,the input impedance of the zero order harmonic frequency is the largest ,and the others reduce successively .There is a fluctuation when it comes to the second order harmonic frequency ,which accords with the physiology fact. The frequency of the stenosis amplitude oscillatory makes the input impedance periodically change in a cardiac cycle. But the character of the wall of the tube has little effect on the input impedance.

Abstract:To investigate the repairing mechanism of necrotic femoral head treated with Shengmai Chenggu capsule, we measured the mechanical properties and biochemical components of steroid-induced necrosis of femoral head in the rabbits. The results revealed the mechanical properties osteocalcium, the ratio of Ca/P and collegen of the femoral head in the group treated with Chinese herb were better than those in the group control and model. It indicated Shengmai Chenggu capsule can modify biochemistry metabolism, improve necrotic bone repairing.

Abstract:Experiments of the tension and hysteresis and relaxation of the valve of veins in various sections were used in this part of the study. Results indicated that valve of vein had property of the hysteresis and that valve of vein in various sections had variant tensional forces. This study explored biomechanical property of the valve of the valve of veins. The data and results can be served as the selection of the artificial material of the valve and provide scientific basis for further study.

Abstract:To evaluate the effects of Xian Zhen Gu Bao on glucocorticoids(GC)-induced cortical bone and cancellous bone in rats with biomechanical way. Methods: 37 male Sprague-Dawley rats were randomly divided into Basal, Aging, Hormone group and lower, middle, high dose group of Xian Zhen Gu Bao. the latter 4 groups was given prednisone acetate (4.5mg/kg) twice a week, meanwhile, lower, middle, high dose group of Xian Zhen Gu Bao were respectively given 0.2、0.4 and 0.8mg/kg/d，6 times a week. The torsion, three-point bending and compression tests were respectively made on femurs and 5th lumbar vertebrae of three groups after 3 months. Results: In GC group, the loads imposed on the femoral middle segments in three-point bending in compression tests were separately decreased by 17.1%(p<0.05) though the rest parameters tended to decrease, compared with the control group, while the treatment groups used lower, middle, high dose group of Xian Zhen Gu Bao can prevent GC-induced mechanical characters of femurs and lumbar vertebrae in rats from decline. Conclusion: When GC used for a long time, the biomechanical characters of cortical and cancellous bone in the rats would be led to decrease, on the contrary, the decline of GC-induced mechanical characters can be arrested by using Xian Zhen Gu Bao.

Abstract:The strength of the teeth with subclinical fractures which are cured with miniature SMA staples is analysed and studied using bending theory, tensile theory and experimental method in material strength. It is included that the strength of teeth with subclinical fractures which are cured with miniature SMA staples is 2236 symbol 177 "Symbol" s 10.5眪 1654 N, the strength of teeth with subclinical fractures which are not cured with miniature SMA staples is 1348 symbol 177 "Symbol" s 10.5眪 947 N, and that the strength of teeth with subclinical fractures which are cured with miniature SMA staples is obviously greater than that of the teeth with subclinical fractures which are not cured with miniature SMA staples（P < 0.05）.

Abstract:Objective: To study the relationship between the preservating time of deep frozen cryopreservating allograft and the biomechanical properties. Method: Specimens of the fibular bones of deep frozen cryopreservation for 1 and 7 years were made into test pieces of torture and compaction.And the bending strength(BS) ,modulus of elasticity(ME) and compact strength(CS) were measured on the INSTRON1195 electronic tensile test machine.And the results were analysised with T test. Results:The 1 year group and the 7 year group had no significant difference in trems of BS(P>0.05) ,ME(P>0.05) and CS(P>0.05). Conclusion: Cryopreservation had no effects on the cortical bone biomechanics ,as long as not contaminated, the cryopreservation will be independent of storage time and the pre- or pro- operation treatments.

Abstract:With the power-law relaxations and creeps, the analysis on the experimental results of some Soft tissues (i.e. cartilage, artery, ureter, mesentery etc.) was given. It was found that the power-law model could show up their mechanical properties.

Abstract:Obstract: Through the development of traditional steel plate according to the biomechanic principle of fracture stabilization, author developed a new kind of internal fixture-compress steel plate of gear contact half cycle and channel type（GCC）and then made a biomechanic test on it in order to provide experimental bases for safety clinical practice。METHOD：Nine fresh adult moist cadaveric humerus specimens used in the experiment were divided into three groups at random。Normal bone group（N），Test group（GCC）and general compress plate group（GCP）were made biomechanic test respectively and the experimental data were analysed。RESULTS:The effect of fixation strength，stiffness，stability and ultimate compress strength by GCC is better than that of general compress plate(GCP)。CONCLUSIONS：Being used in long bone fracture，the internal fixture of GCC is firm，dependable and GCC'S biomechanic performance is superior。This instrument of reasonable structure is safe，simple and practical and it can be widely used in clinical practice。