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  • 1  Biomechanical study on helical long PHILOS plate fixation for proximal metaphyseal-diaphyseal humeral shaft fractures
    WANG Lei CHEN Yan-hao LU Chun-xia
    2015, 30(5):463-467. DOI: 10.3871/j.1004-7220.2015.05.463
    [Abstract](62365) [HTML](0) [PDF 1.24 M](40)
    Abstract:
    Objective To compare biomechanical properties of the helical and straight long PHILOS (proximal humerus internal locking system) plates (Synthes Inc., Switzerland), so as to provide some biomechanical evidence for treating proximal metaphyseal-diaphyseal humeral shaft fractures in clinic. Methods Twelve Synbone artificial bones of right humerus (SYNBONE Inc., Switzerland) were divided into two groups. In control group (n=6), the humerus was fixed with the 10 hole long straight PHILOS plate, while in experimental group (n=6), the humerus was fixed with the same long PHILOS plate which was precontoured for moulding (i.e. helical PHILOS plate). After the proximal metaphyseal-diaphyseal humeral shaft fractures were made in all artificial bones, the biomechanical properties of the specimens in two groups under 6 loading modes (i.e., axial tension and compression, torsion in the same and reverse direction, medial-lateral and anterior-posterior three-point bending) were tested en bloc and compared. ResultsCompare with control group, under 100-500 N tensile and compressive loads, the axial displacement at the fractured end in experimental group increased by about 95% and 58%, respectively. Under 0.6-3 N?m torsional moment in reversed direction, the tensional angle in experimental group was obviously smaller than that in control group, with a decrease of 55%-64%. Under medial-lateral bending moment of 1.5 and 3 N?m, no significant difference was found in deflection of the experiment and control group, while under medial-lateral bending moment of 4.5, 6 and 7.5 N?m, the deflection in experimental group decreased by 20% 30% as compared to control group. Under 0.6-3 N?m torsional moment in the same direction and 1.5-7.5 N?m anterior-posterior bending moment, both the torsional angle and the deflection in experimental group were larger than those in control group, with a significant difference (P<0.05). Compared with control group, the tensile stiffness and compressive stiffness decreased by 49% and 36%, the torsional stiffness in the same direction decreased by 19% and that in reversed direction increased by 150%, three-point bending stiffness in medial lateral direction increased by 18% and that in anterior posterior direction decreased by 70% in experimental group, all with a significant difference (P<0.05). ConclusionsCompared with the long straight PHILO plate, the long helical PHILOS plate has better biomechanical properties, which can meet the clinical need of proximal metaphyseal-diaphyseal humeral shaft fracture fixation and postoperative rehabilitation. This surgical technique is expected to be widely applied in clinic, especially with the advantage of minimal invasive surgery.
    2  Analysis on microstructure and biomechanical properties in different regions of osteoporotic femoral head
    ZHANG Xiang-yan LIANG Chao-g TANG Xian-zhon YANG Wei WANG Jia CHEN Hao-jie ZHANG Guo-ning YU Zhi-feng
    2017, 32(1):77-82.
    [Abstract](47526) [HTML](0) [PDF 1.30 M](35)
    Abstract:
    Objective To investigate the structure and biomechanical property differences in different regions of the femoral head for elderly patients with femoral neck fractures, and to study its influence on internal fixation for fracture. Methods Twenty femoral head specimens were collected from elderly patients with femoral neck fracture after joint replacement. The femoral head was divided into 3 parts (lateral, inferior and medial region) with reference to anatomical markers on surface of the femoral head. After the position and drilling direction of the ring drill were determined, a circular drill was used to obtain the cylindrical cancellous bone columns with 10 mm in diameter and 10 mm in height. The data of cancellous bone columns in different regions were analyzed by Micro-CT scanning system, including bone volume fraction (BVF), trabecular space (Tb.Sp), trabecular thickness (Tb.Th), the number of trabecular number (Tb.N), the bone surface volume ratio (bone surface/bone volume, BS/BV), structural model index (SMI). Mechanical property differences of bone tissues in different regions were calculated by micro-finite element analysis. ResultsBone mass in the elderly osteoporotic femoral head decreased, and there were significant differences in bone microstructure and mechanical properties in different regions of the femoral head. Bone microstructure and mechanical properties in medial region were obviously superior to those in lateral and interior region. Conclusions The bone structure and mechanical strength in medial region of the femoral head are obvious superior to those in lateral and inferior regions. The position for internal fixation should be fully considered during treatment of osteoporotic femoral neck fracture in clinic.
    3  Evaluation of unicondylar knee arthroplasty and fibulectomy from a biomechanical viewpoint
    祁昕征,张家铭,谭传明,张英泽,郑诚功
    2016, 30(5):479-487. DOI: 10.3871/j.1004-7220.2015.06.479
    [Abstract](36917) [HTML](0) [PDF 2.54 M](2)
    Abstract:
    Varus deformation in knee joint is one of the common symptoms caused by unicompartment knee osteoarthritis. Currently, several operations can be used for correcting such deformation, including high tibial osteotomy, unicondylar knee arthroplasty (UKA) and fibulectomy. UKA has been developed for over 60 years, with the advantage of normal knee kinematics restored, less incision, more bony tissue preserved and larger range of motion than total knee arthroplasty (TKA). Therefore, UKA has become a reliable method for treating unicompartment knee osteoarthritis. Fibulectomy is a new kind of surgical technique for treating varus deformation in knee joint, with the advantage of simple operation, low cost and fast recovery. At present, fibulectomy has been widely applied, but its treatment mechanism is still not clear. In this review, two clinical operations UKA and fibulectomy were summarized, and the possible mechanism of fibulectomy for treating unicompartment knee osteoarthritis was proposed from the viewpoint of biomechanics. The author hypothesized that reduction in lateral muscle force after fibulectomy would cause rebalance of the resultant joint moment, therefore, the change of joint contact position and the decrease in joint contact force might be the cause of fibulectomy to release the pain for knee osteoarthritis patients.
    4  The Role of LncRNA in Bone Remodeling and Skeletal Diseases
    WEI Shuping ZHANG Xizheng
    2018, 33(6):572-576.
    [Abstract](15494) [HTML](0) [PDF 0.00 Byte](0)
    Abstract:
    Bone remodeling can keep the biomechanical properties, which is of great significance to maintain bone strength. Normal skeletal development requires tight coordination of transcriptional networks, signaling pathways and biomechanical cues, and many of these pathways are dysregulated in pathological conditions affecting bone. lncRNA is a group of RNAs with broad biogenesis, which are longer than 200 nt and highly conserved in their secondary and tertiary structures. Studies show that many lncRNAs are involved in normal development or balance of the skeletal system, the regulation of osteoblast differentiation, and the pathogenesis of osteosarcoma. Dysregulation of lncRNA expression is closely related to many bone diseases and it is expected to be a biomarker for predicting bone diseases. In this review, the characteristics and mechanisms of lncRNA involved in bone remodeling and its possible role were summarized, and the likely utility of IncRNAs as biomarkers and therapeutic targets for diseases of the skeletal system was discussed, including osteoarthritis, osteoporosis, and cancers of the skeletal system, so as to provide references for the better understanding and study on lncRNA biological function in organisms.
    5  Biomechanics Analysis on Human Heart by Establishment of three-dimension Model and Finite Element Method
    FANG Hong-rong ZHUANG Zhuo
    2008, 23(1):43-46. DOI: 10.3871/j.1004-7220.2008.01.46.
    [Abstract](11877) [HTML](0) [PDF 0.00 Byte](480)
    Abstract:
    Objective To establish a three-dimensional (3D) geometrical and gridding model of human heart, and carry out the finite element (FE) simulation. Method With visible data of digital human heart, a 3D structures of the heart s configurations and interior structures are constructed by software 3D-DOCTOR and SOLIDWORKS. The model has been imported into FE software ABAQUS by format STEP. The natural frequency and the stresses of the model are analyzed under the blood pressure. Result The digital model of the human heart has been developed, which could provide the 3D configurations and interior structures as well as the volume of the heart. The different mechanics behaviors in different regions within the heart has been demonstrated. The frequency and the stresses of the heart from 3 different regions have been obtained under blood pressure. Conclusions A 3D visualization geometrical and gridding model of the heart is developed by digital human data, which can show the configurations and internal structures of the heart. By using FE method, the model can be used to provide a visualization numerical simulation platform for biomechanics analysis of the heart.
    6  Fatigue Life Analysis of Coronary Stent
    LI Jian-jun LUO Qi-yi XIE Zhi-yong LI Yu
    2010, 25(1):68-73. DOI: 10.3871/j.1004-7220.2010.01.73.
    [Abstract](10188) [HTML](0) [PDF 709.16 K](6636)
    Abstract:
    Abstract Objective After the implantation, coronary stent was expected at least to keep integrity and maintain the predicated function for over 10 years or 4e8 cycles under the pulsatile loading conditions, and the fatigue property of the stent should be evaluated. Method The finite method was used to analyze the stress distribution of different phases and evaluate the fatigue life according to Goodman criteria, meanwhile, the accelerated fatigue experiment was also performed . Results It could be concluded that the dangerous points were located in the lateral inner surface of stent curvature. Conclusion The results proved that the fatigue property could be simulated through the finite element analysis, which can provide the theoretical guidance for the stent design.
    7  Status and progress of tissue engineering research
    ZHANG Xi-zheng
    2010, 25(1):1-3. DOI: 10.3871/j.1004-7220.2010.1.3.
    [Abstract](10121) [HTML](0) [PDF 404.53 K](5614)
    Abstract:
    Tissue engineering is one of the most promising subjects,which has broad application prospects in the fields of regenerative medicine and human health care. According to the papers published in this current issue about scaffold material preparation and mechanical environment affection to cells during the construction process of tissue engineering, this paper describes the current status and progress of tissue engineering research at home and abroad, indicating that tissue engineering research is developing to a deeper and wider field.
    8  Effects of adhesive thickness on internal stress distribution in full-ceramic crowns
    LIN Bin LU Cheng-lin ZHANG Xiu-yin ZHANG Dong-sheng
    2010, 25(1):56-62. DOI: 10.3871/j.1004-7220.2010.01.62.
    [Abstract](9881) [HTML](0) [PDF 768.15 K](5241)
    Abstract:
    Objective The objective of this study is to investigate the effects of the thickness of the adhesives (3M ESPE RelyX ARC) on the internal stress distribution of the IPS Empress II full-ceramic crowns using Finite Element Analysis (FEA). Methods A dummy Empress II ceramic crown restoration of the mandible right first molar was prepared according to standard dental process. Followed by micro-CT scanning, four 3D numerical models with cement thickness 60, 90, 120 and 150μm were established. The models were subjected to four loading conditions and stresses in veneer and core layers were presented. Results Numerical results indicate that when adhesive thickness increases from 60μm to 90μm, the maximum principal stress either in veneer or core decreases. However, when thickness increases to 150μm, stress variation trends differ from adhesives. Conclusion The normal stresses in adhesives remain a low level when the thickness varies from 90μm to 120μm, while the shear stress is less sensitive to the thickness when it exceeds 90μm. There is an optimal thickness which can reduce the tensile stress in the core and veneer. Attention should be paid to the shear strength of the adhesives since the shear stress could cause failure in the adhesive layer.
    9  Biomechanics of lumbar spondylolysis : Finite element modeling and validation
    GU Xiao-min JIA Lian-shun CHEN Xiong-sheng LU Cheng-lin LIU Yang ZHANG Dong-sheng
    2010, 25(1):45-50. DOI: 10.3871/j.1004-7220.2010.1.50.
    [Abstract](9595) [HTML](0) [PDF 749.69 K](5986)
    Abstract:
    Objectives To construct three-dimensional finite element model of lumbar spondylolysis, then to verify its validity by comparison of biomechanics in vitro. Methods According to the radiological data of a patient with lumbar spondylolysis, the bone and intervertebral disc of L4-S1 were reconstructed by Simpleware software. The lumbar attaching ligaments and articular capsule were added into simulating model by Ansys software. Finally, the three-dimensional finite element model of lumbar spondylolysis was simulated successfully, and validated by lumbar spondylolysis biomechanical experiment in vitro. Results The reconstruction of digital model is contained of the bones of lumbar spine which includes of vertebral cortical bone, cancellous bone, facet joint, pedicle, lamina, transverse process and spinous process,as well as annulus fibrosus, nucleus pulposus,superior and inferior end-plates. Besides, anterior and posterior longitudinal ligaments, flavum ligament, supraspinal and interspinal ligaments and articular capsule of facet joint are also attached. The model consisted of 281,261 nodes and 661,150 elements. Imitation of spondylolysis is well done in this model. The validity of the model is verify by comparison of the results of biomechanics in vitro which involved in the trends under loading of stress/strain of L4 inferior facet process, L5 superior and inferior facet process, S1 superior facet process and the trend of stress/strain of lateral and medial L4 inferior facet process. Conclusions Lumbar spondylolysis is reconstructed to three-dimensional model using finite element analysis, and can be further used in the research of biomechanics of lumbar spondylolysis.
    10  Evaluation of in vitro cytotoxicity and drug release property on pharmaceutical dressing
    HUANG Shu-jie GUAN Jing LI Zhi-hong ZHANG XI-zheng WU Ji-min
    2010, 25(1):32-35. DOI: 10.3871/j.1004-7220.2010.01.35.
    [Abstract](9310) [HTML](0) [PDF 480.67 K](4987)
    Abstract:
    Objective To evaluate the cellular toxic and release of pharmaceutical dressing. Methods Following the State standard GB/T14233.2-2005, the L929 cellular morphology was observed by inverted 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. 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 288nm and the dissolved liquid in1/6, 1/2, 1, 3, 16, 24, 36 and48h. Results The average cell RGR of the pharmaceutical dressing was 91.25% and reached 1 grade. L929 cellular morphology was normal. Pharmaceutical dressing release accord to Higuchi equation,and the simulated equation is Mt/M∞=0.3271t0.239. Conclusion Biologic compatibility of the pharmaceutical dressing is good, and the release of levofloxacin from the pharmaceutical dressing is sustained in vitro.
    11  Finite element analysis on mechanical responses of human torso with body armor to non penetrating ballistic impact
    DONG Ping CHEN Jing ZHANG Qi-kuan KANG Jian-yi LIU Hai ZHANG Liang-chao XU Cheng
    2012, 27(3):270-275. DOI: 10.3871/j.1004-7220.2012.03.275.
    [Abstract](9223) [HTML](0) [PDF 12.44 M](14588)
    Abstract:
    ObjectiveTo develop a finite element computational model of the torso for the numerical simulation of mechanical responses of human torso to non-penetrating ballistic impact. MethodsBased on the CT data of a Chinese adult man, the finite element model of human torso was created by using the medical image processing software Mimics and the finite element pre-processing software HyperMesh. The pressure and acceleration response of the human torso outfitted with soft body armor to the ballistic impact from 9 mm ammunition at a velocity of 360 m/s was calculated numerically by the explicit finite element code LS-DYNA. ResultsThe finite element model of human torso including thoracic skeletal structure, organs, mediastinum and muscle/skin was established. The pressure response of heart, lung, liver and stomach, as well as the acceleration response of sternum were obtained by numerical calculation. It was found that the peak pressure and its time phase were dependent on the distance between the impact point and the measured point wherever in various organs or different position of an organ. Conclusions The finite element computational model of human torso outfitted with soft body armor is available for the simulation of human response to non-penetrating ballistic impact, and the simulated response can be used as evidence for the investigation on mechanism and protection of behind armor blunt frauma.
    12  Application of atomic force microscopy in ultrastructure and biomechanics of cells and biomacromolecules
    ZHU Jie GUO Lian-hong WANG Guo-dong OUYANG Wu-qing
    2012, 27(3):355-360. DOI: 10.3871/j.1004-7220.2012.03.360.
    [Abstract](8718) [HTML](0) [PDF 12.98 M](22730)
    Abstract:
    To be the representative fruition resulted from the rapid development in micro-nano theory and technology, atomic force microscopy (AFM) has greatly promoted the expansion of biological research in micro-nano scale, and facilitated the birth and development of micro-nano biology as an important technique in its 25-year evolutional progress. Based on the fundamental principles and detection modes of AFM, as well as the author’s research findings and work experience in this field, the paper reviews the application of AFM in the study on ultrastructure and biomechanical properties of cells and biomacromolecules in the aspects of biological structure and morphology, surface physicochemical characterization and mechanical manipulation of biological macromolecules, and focus on some important scientific and technical problems on AFM in micro-nano biomedical research needed to be improved and solved urgently, with exploratory insights and recommendations for potential users in ultrastructure and biomechanics of cells and biomacromolecules.
    13  Investigation on Mechanical Property of the Compound Scaffold of Sol-Gel Bioactive Glass/Collegan
    ZHANG Juan-juan MENG Yong-chun CHEN Xiao-feng LI Yu-li LUO Xiaogang LIN Cai
    2010, 25(1):16-20. DOI: 10.3871/j.1004-7220.2010.01.20.
    [Abstract](7696) [HTML](0) [PDF 703.81 K](4575)
    Abstract:
    Objective To investigate the mechanical prosperity and degradation rate of the scaffolds by compounding collagen and the nano sol-gel derived bioactive glass were studied in this paper,and that would provide the theoretical basis for the further application of collagen based scaffold. Method The scaffold by 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. To affect the aggregation state of the collagen fibers with adjusting the supplementation of bioactive glass, then the microstructures of the compound scaffold would be different. At last, the compound scaffolds with different mechanical properties were prepared. Results (1) As the aggregation state of the collagen fibers changed, the scaffold with the coarser collagen fibers with the diameters 400-600nm approximately is prepared. The coarser collagen fibers would 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 scaffold is lower than 20%, the secondary structure of collagen is damaged severely. Conclusions The composite scaffold with the mass ratio of collagen to bioactive glass to 40:60 has the best performance in mechanical property and degradation, which would be helpful for further applications
    14  Influences of cyclic tensile strain on proliferation of preosteoclasts and osteoclasts and tartrate resistant acid phosphatage
    GUO Yong GUO Chun YAN Yu-xian LI Rui-xin LIU Lu HAO Qing-xin ZHANG Xi-zheng SHI Cai-hong
    2012, 27(3):299-304. DOI: 10.3871/j.1004-7220.2012.03.304.
    [Abstract](7630) [HTML](0) [PDF 19.90 M](11039)
    Abstract:
    Objective To investigate the effect of mechanical loading with different magnitudes on the proliferation, differentiation and activity of preosteoclasts and osteoclasts. Methods One group of RAW264.7 preosteoclastic cells cultured in osteoclast inductive medium were subjected to the cyclic tensile strain for three days, and then cultured for four days; the other group of RAW264.7 cells were induced in osteoclast inductive medium for four days to be osteoclasts, then subjected to the cyclic tensile strain for three days. Results Under the tensile strain at different magnitudes, the proliferation variations in two groups of RAW264.7 cells were approximately identical, but changes in the activities of tartrate-resistant acid phosphatage (TRAP) and numbers of TRAP-positive multinucleated cells (osteoclasts) in the two groups were significantly different. Under the moderate tensile strain (2 500 με), the reduction of TRAP activity and osteoclasts number were both the highest in the first group, and both the lowest in the second group. Conclusions The influence of different tensile strain on osteoclast differentiation and osteoclastic activity of preosteoclasts in early differentiation is different to that of the preosteoclasts already differentiated into osteoclasts.
    15  Three-dimensional finite element numerical analysis of the Ni Ti shape memory alloy clutching internal fixator
    CHEN Guo-ping FAN Yu-bo ZHANG Dai-quan
    2010, 25(1):36-39. DOI: 10.3871/j.1004-7220.2010.1.39.
    [Abstract](7362) [HTML](0) [PDF 448.75 K](5159)
    Abstract:
    Objective Clutching internal fixtor (CIF) loose and the fixed part weakly heal up are often found in orthopedic clinic.In the present paper, biomechanics methods were used to try to explain and analyze these issues, provide a helpful suggestion for the application of CIF in clinic. Method Commercial finite element method(FEM) Program ANSYS was applied to set up the Finite Element Models of orthopedic CIF and bone tissue to analyze and evaluate the biomechanical performances of the Ni Ti shape memory alloy CIF. Results There is an interaction force between embracing force of CIF and resistant force of bone tissue during the orthopedic clinical treatment. The embracing force along two semi-circular arms of CIF is increasing from the open position and reached the maximum value at the open symmetry position where the deformation of the bone occurre. Conclusion It is the key to choose the force loading position during the practical treatment, as the concentration force is the main force when there is an interactive force between the bone and the CIF.
    16  European Virtual Physiological Human
    Marco Viceconti Gordon Clapworthy Fulvia Taddei Serge Van Sint Jan
    2008, 23(1):19-25. DOI: 10.3871/j.1004-7220.2008.01.25.
    [Abstract](7362) [HTML](0) [PDF 0.00 Byte](450)
    Abstract:
    The Virtual Physiological Human is an initiative that is strongly supported by the European Commission for the development of an integrated model of human physiology at multiple scales from the whole body through the organ, tissue, cell and molecular levels to the genomic level. Its development was considerably advanced by the activities of the STEP project, a Coordinated Action funded by the EC, which began in early 2006. This paper provides an overview of the VPH and the developments it has engendered in the rapidly expanding world-wide activities associated with the physiome. It then focuses on one particular project, the Living Human Project, to illustrate the type of advances that are taking place to further the aims of the VPH and similar initiatives worldwide.
    17  Preparation and Characteristics of Patterned TiO2 Thin Film onTC4 Made by Sol-gel Method
    LIU Ying ZHANG Wen-guang
    2010, 25(1):21-25. DOI: 10.3871/j.1004-7220.2010.1.25.
    [Abstract](7201) [HTML](0) [PDF 567.23 K](5237)
    Abstract:
    Objective To improve the long-term biocompatibility and mechanical stability of Titanium alloy implants. Method micro-nano patterned TiO2 thin films have been prepared on TC4 substrates via a sol-gel dip-coating method with Ti(OC4H9)4 (TEOT) as precursor and polyethylene glycol (PEG) as organic template. The influence of PEG concentration upon the morphology of the target films has been studied by using AFM. The wettability and tribological properties of the target films have been studied by means of optical contact angle measuring instrument and UMT-2. Results When increasing the PEG concentration to 3.5g/100mL, a parallel arranged groove structure can be obtained on the surface of the sample; compare with TiO2 sol-gel film without adding organic template, the wear resistance of the patterned film is better. Conclusions The feature of the patterned TiO2 films can be controlled by adding different amount of organic template; and it has been proved that a certain kind of patterned structure can improve the wear resistance of the film.
    18  JCS-based method on coordinate transformation of attachment points between muscle and bone
    TANG Gang JI Wen-ting LI Yuan-chao WANG Cheng-tao
    2010, 25(1):40-44. DOI: 10.3871/j.1004-7220.2010.01.44.
    [Abstract](7124) [HTML](0) [PDF 480.96 K](4945)
    Abstract:
    Objective In order to avoid potential injuries imposed to human body, it can 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. Methods We reconstruct the lower limb musculoskeletal model and define the uniform joint 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.
    19  Effects from different head models on dynamic response of the head impact using material point method
    ZHOU Shuang-zhen ZHANG Xiong MA Hong-lei
    2013, 28(2):142-147. DOI: 10.3871/j.1004-7220.2013.2.147.
    [Abstract](7012) [HTML](0) [PDF 2.31 M](3070)
    Abstract:
    Objective To investigate the effects of muscles and boundary conditions on head impact response. Methods Three different 3D material point impact models of human head were constructed from the CT scanned images. The first model was the simple head model (SHFr) including skull, membrane and brain, in which the head was free. The second model was the simple head model with muscle (MHFr) including skull, membrane, brain and muscle of the head, in which the head was free. The third model was the MHFr model with shoulder, in which the bottom edge of the shoulder was fixed (MHSFi). The three models were under the impact of a cylindrical lead hammer projected at a speed of 6.4 m/s to simulate the dynamic response of the three models using 3D explicit material point method code. Results The peak values of acceleration of the head centroid for the SHFr, MHFr and MHSFi model were 6.018×103, 4.69×103 and 4.76×103 m/s2, respectively. Conclusions The muscle of the head can disperse distributions of the contact force, enlarge the damage area and relieve the damage of the head. In case of short-time impact, whether the boundary of the head is free or the shoulder is fixed does not affect the dynamic response of the head impact.
    20  Recursive calculation and parameter analysis on input impedance of arterial tree based on electric network model
    XIAO Han guang HE Wei LIU Xin hua LI Song nong BI Xi fei
    2011, 26(1):18-23. DOI: 10.3871/j.1004-7220.2011.01.23.
    [Abstract](6885) [HTML](0) [PDF 1.81 M](3991)
    Abstract:
    Objective In order to provide a reference for analysis of the pathophysiological changes of human arterial tree, the effects of the arterial parameters on input impedance of arterial tree were studied by proposing a recursive algorithm to calculate the input impedance. Method A distributed electric network model was constructed for the arterial tree which consisted of 55 segments accounting for all the central vessels and major peripheral arteries. By setting up the peripheral resistance of the model and constructing a unilateral data link list of the arterial tree, the recursive algorithm was employed to compute the input impedance of ascending aorta in the arterial tree. Then, comparisons of the effects of arterial compliance, peripheral resistance, length, internal radius and wall thickness on the input impedance were made based on the recursive algorithm. Results The computational results were in accord with experimental data and results of other models, and proved the validity of the model and algorithm. The input impedances of the arterial tree showed significant influence with different characteristics for different parameters. Conclusions The input impedance of arterial tree can reflect the changes of the hemodynamic parameters effectively, which is an important reference for the pathophysiological diagnosis of human arterial tree.

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