Objecthe Children's heart valves by Dual-Source Compater Tomography(DS CT)images were enhanced and segmented in order to reconstruct 3D construction of heart valves and make motion analysis based on this model.Method,Adaptive seed-filling algorithm is proposed in this paper to segment interested region of heart based on DS CT images.Contoudet transform is used to enhance and segment heart valve based on the part-segmented image.Result With these methods,DS CT images were SUCCESS fully pro-cessed and segmented in Matlab 7.0 and clear images of mitral valves were got.Condusions The adaptive seed-filling algorithm proposed in this paper and Contourlet transform are very useful for segmentation in dif-ferent situation.The experimental result in this paper proides useful reference for doctors in their research on the motion of mitral valves and planning on surrgical operation of mitTal valves.

Objective To evaluate the cellular toxic and release of pharmaceutical dressing.Method Following the State standard GB/T14233.2-2005.the L929 cellular merphology was observed by inveded microscopy after 72h and proliferation of the cells was examined using mitochondrial function(MTT)assay.Relative growth rate (RGR)was calculated and cytotoxicity grade was evaluated by absorbency(OD)data.With PBS7.4 as dissolution media,and(32±0.5)℃as dissolution temperature,the release rate was determined with UV method with the determination wavelength of 288 nm and the dissolved liquid in 1/6,1/2,1,3,16,24,36 and 48 h.Results The average cell RGR of the pharmaceutical dressing is 91.25%and reaches 1 cytotoxicity grade.L929 cellular morphology is normal.Pharmaceutical dressing release accord to Higuchi equation,and the simulated equation is M_t/M_∞=0.3271t~(0.239).Conclusions Biologic compatibility of the pharmaceutical dressing is good,and the release of levofloxacin from the pharmaceutical dressing is sustained in vitro.

Objective The mechanical model of nonlinear blood flow in large blood vessels is developed and the propagation of nonlinear pressure wave is studied.Methods Taking the effect of large deformation,nonlinear equation of motion was established in the current configuration in terms of the constitutive equations proposed by Demiray for soft biological tissues.Resuit Employing the reductive perturbation method the KdV equation is derived from the nonlinear partial equations governing the motion of coupled system.Conclusions It is shown from this study that the system may have an accurate periodic wave solution or solitary wave solution under certain conditions.

Hemodynamics-simulation-based cardiovascular surgical planning.which is the patient-specific surgical hemodynamics optimization based on medical image,is the further development of clinical-applica-tion-oriented computational hemodynamics,it is very helpful for cardiovascular surgical decision-making.The art-in-work of hemodynamics-simulation-based cardiovascular surgical planning in both domestic and over-seas research was reviewed,the key problems and solutions involved were analyzed,and the further develo-ping objectives were presented.

Objective To compare the compression properties of articular cartilage and polyinyl alcohol hydro-gel(PVA-H)as artificial carlage.Method Unconfined compression tests were conducted on articular card-lage and PVA-H,including stress-strain tests,creep tests and stress relaxation tests.The stress-strain rela-tionship of articular cartilage and PVA-H were measured.Result The compression modulus of articular card-lage was higher than that of PVA hydrogel.The average compression modulus of articular cartilage and PVA hydrogel was(3.6492±0.6199)Mpa and(1.5951±0.1469)Mpa,respectively.Condusions The experimental results revealed the differences existed between articular cartilage and PVA-H and this would be useful to fur-ther improve the mechanical properties of artificial cartilage.

Objective To investigate the mechanical prosperity and degradation rate of the scaffolds with compounding collagen and the nano sol-gel derived bioactive glass were studied,and provide the theoretical basis for the further application of collagen based scaffolds.Method The scaffold with compounding collagen and the nano sol-gel derived bioactive glass(58S)were prepared using the freeze-drying techniques with the bioactive glass as phase addition.By affecting the aggregation state of the collagen fibers with adjusting the supplementation of bioactive glass to change the microstructures of the compound scaffolds and finatly the compound scaffolds with different mechanical properties were prepared.Results (1)As the aggregation state of the collagen fibers changes,the scaffolds with the coarser collagen fibers is prepared with the diameters 400-600 nm approximately.The coarser collagen fibers will play an important role in improving the mechanical property and slowing down the degradation rate of the collagen based scaffolds.(2)The interactions between bioactive glass and collagen are studied by FTIR and Raman technologies.When the quality of content of collagen in the compound scaffolds is lower than 20%,the secondary structure of collagen is damaged severely.Conclusion The composite scaffolds with the mass ratio of collagen to bioactive glass 40:60 has the best performance in mechanical property and degradation,which will be helpful for further applications.

Objective Prepare biomimetic muitilayered scaffold which has similar structure of natural cartilage.Method By lyophilizing the scaffolds which were prefrozen at-20℃ and in liquid nitrogen successively,we prepared double-layered spongy scaffolds.By partially thawing the prefrozen samples and refreezing them in liquid nitrogen before the final liyophilization,we prepared biomimetic multilayered scaffolds with about 2mm thickness.XRD and FT-IR were used to confirm the interaction between collagen and chitosan.SEM was used to observe the morphologies of the scaffolds.The mechanical properties of pure chitosan scaffolds,pure collagen scaffolds,composite single-layered scaffolds and biomimetic multilayered scaffolds were compared both in dry and wet conditions.Results There was chemical interaction between collagen and chitosan.Composite materials will form better pore structure.The biomimetic multilayered scaffolds have upright pores,round pores and a dense layer from bottom to top of the scaffolds.The scaffolds have quite different mechanical properties between dry and wet state.Under wet state,the different layers of the biomimetic muitilayered scaffold have different mechanical properties.Results The biomimetic structure of the multilayered scaffold is very close to that of the natural articular cartilage,and the different layers of the biomimetic muitilayered scaffold had different mechanical properties under wet state.These are hopefully beneficial to help maintain the phenotypes of chondrocytes and promote the repairing effect of cartilage defects.

Objective To adopt a three-dimensional limited element analytic method to research into the cause and mechanism of the complications taking place after resection of head radius.Method To adopt a three-dimensional limited element analytic method to research into the stress transmission action of the head radi-us and the distribution alteration of the stress transmission after resection of head radius impacting on the stability of elbow and wrist.Result In normal cases,the stress value transmitted via head of radius takes 58% of the stress placed,36.85% via humeroulnar joint.The head of radius places a leading role in the stress transmission of the elbow joint.After rasection of the head of radius,the lateral of humeroulnar joint bears about 43% of the stress placed while the medial part bears about 21.6% of the stress.To compare with that before the resection of the head of radius the stress on the lateral is obviously increased more than the medial part.Conclusions The head of radius places a leading role in the stress transm ission of the el-bow joint.The resection of the head radius breaks the normal distribution of the stress on the elbow joint and produces great effect on the stability of the elbow joint and wrist joint.Therefore,in clinics we should pay great attention to the indication of rasection of the head of radius.

Objective In order to avoid potential injuries imposed to human body,it could be feasible to use the musculoskeletal models which can be reconstructed from the cadaver color cryosection(CCC)images,computerized tomography(CT)images,magnetic resonance(MR)images or other images to analyze the dynamic properties of muscles in vivo during human movement.Mothod We reconstruct the lower limb musculoskeletal model and define the uniform ioint coordinate system(JCS)on the model and the subject.The coordinate transformation of the muscle attachment points both on the model and the subject is described in detail.Results The length and the moment arm of the biceps femoris(short head)during knee flexion are calculated and analyzed.Conclusion This method plays an important role in improving the kinematics and dynamic simulation and the muscle force estimation.

Objective To evaluate the biomechanical effects of using a new injectable calcium phosphate cement to consolidate the fixation of osteoporotic intertrochanteric fracture.Method Five matchod pairs of human cadaver femora were used to produce the model of intertrochanteric fracture.All fractures were fixed with dynamic hip screws(DHS),and divided into two groups.In the CPC consolidation group of each pair,CPC was used to grout the hip screw and to fill the posteromedial defect.All femora were subjected to biomechanical test.Results Under the loading of 500 N,in the CPC consolidation group,the mean axial stiffness is(691.93±18.90)N/mm and the horizontal shear stiffness is(5553.84±27.47)N/mm.The mean lateral and medial strength is(5.15±0.35)MPa and(4.13±0.24)MPa.The torsion stiffness was 0.41 and the ultimate loading is(3580±286)N.In the control group,the mean axiak stiffness is(453.45±19.75)N/mm,the horizontal shear stiffness is(3848.87±22.63)N/mm,the mean lateral and medial strength is(3.12±0.37)MPa and(1.80±0.21)MPa,and,the torsion stiffness is 0.35 and the ultimate loading is(2512±189)N.Consolidation fixation with CPC increased each of the biomechanical efficiency(P＜0.05).Conclusions CPC consolidation of osteoprotic femoral head and the medial defect of intertrochanteric fracture can significantly improve the overall stability and decrease the rate of postoperative complication.