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Published: August 22, 2001
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Article type: Appendix
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Published: August 22, 2001
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Article type: Appendix
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Published: August 22, 2001
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Article type: Appendix
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Published: August 22, 2001
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Article type: Index
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Published: August 22, 2001
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Hiroshi YAMADA
Article type: Article
Session ID: F-0801
Published: August 22, 2001
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A finite element analysis program was developed for an incompressible transversely isotropic hyperelastic material to describe the anisotropic deformation of blood vessels. The elastic tensor, which relates the Truesdell rate of the Cauchy stress tensor with the rate of deformation tensor, was derived for an exponential type of strain energy density function. To validate the implemented model, a uniaxial compression test was carried out with one finite element. The result of the finite element analysis showed a good agreement with analytical solutions.
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Masakazu KUME, Toshio TUTA, Takeshi IWAMOTO
Article type: Article
Session ID: F-0802
Published: August 22, 2001
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A wrinkle is formed by muscular contraction is repeated many times or aging. That tissue around of wrinkle is different from other parts. It is important to know the influence which the stress gives to skin, in the viewpoint of the beauty or the treatment for the wound in plastic surgery. This paper presents a method of finite deformation analysis for combinative probrems in stress deformation of solid matrix and in permeation flow of fluid of a living soft-tissue. Living soft-tissue is consisting of two principle phases. This biphasic material with a solid matrix (collagen fibrils and elastin fibrils) and the interstitial fluid (water) has combination problems in stress deformation of solid matrix and in permeation flow of fluid. Thus we let the equation which combined the hyperelastic constitutive equation for skin and under-skin tissues with Darcy's law in permeation and continutive equation of fluid flow. The program was developed based on this equation, and simulation was done.
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Takuji KOIKE, Hiroshi WADA, Toshimitsu KOBAYASHI, Alexander M. Huber
Article type: Article
Session ID: F-0803
Published: August 22, 2001
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The middle ear plays an important role in auditory mechanics, transmitting sound signals efficiently from the ear canal to the cochlea. If ligaments, which support ossicles, become fixed, conductive hearing loss occurs. A diagnosis of these fixations of the ligaments is difficult. Especially, as the anterior malleal ligament (AML) is a tiny ligament, its fixation is often overlooked. In this study, the effect of the AML fixation on the middle-ear vibration was analyzed by using a finite-element model of the middle ear and by measuring vibrations of temporal bones with a laser Doppler interferometer. Then, based on our findings, a diagnostic method for detecting the AML fixation was suggested.
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Yoshimune MISAWA, Yoshihisa MINAKUCHI
Article type: Article
Session ID: F-0804
Published: August 22, 2001
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In order to restore damaged joint functions, prosthesis has been widely implanted into the joint part in recent years. However, the biononconformance often occurs after the reimplantation. In this paper, the shape optimization of a hip prosthesis stem in the total hip replacement was investigated using growth-strain method. At first, growth criterion parameters of femur were sought by applying finite element method for the mechanical adaptive growth behavior of femur. By this analysis, the effect of stress shielding on femur inserted with the prosthesis stem was investigated. Then, the optimum shape of the prosthesis stem was created by growing the stem not so as to be occurred the bone resorption on femur. It was found that the bone resorption of femur was the smallest when the stem area was at 80 % of the initial stem area.
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Kouhei MURASE, Yasuhisa OKUMOTO
Article type: Article
Session ID: F-0805
Published: August 22, 2001
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The purpose of this research is to investigate the estimation index of the contour shape in order to improve the fidelity of the three dimensional human finite element model. Two construction methods were examined, and the fidelities of the contour shape were estimated by 'fractal dimension'. In the theoritical evaluation on various slice heights and angles, fractal dimension at 1-directional constraction method was less continual than at 2-directional one. And the contour shape at a uncontinual region was different from the original one. These results indicate that the estimation index is effective for verifying the fidelity of biomechanical FEM modeling.
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Sota YAMAMOTO, Eiichi TANAKA, Yuki WATANABE, Kunji NAGAE
Article type: Article
Session ID: F-0806
Published: August 22, 2001
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This study is concerned with the mechanical causes of isthmic spondylolisthesis. The effects of disc degeneration on instability of isthmic defect vertebrae are discussed by using finite element analyses. The finite element model of disc is refined based on the model used in former study. Disc degeneration is modeled as a change of mechanical properties of annulus fibrosus. The results of flexion motion analyses show that the percentage of slipping is decreased by the change of mechanical properties of disc however the decrease of instability is not significant quantitatively. As slip angle is significantly increased, it may cause an initial damage of tissue in the disc.
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Shunji HIROKAWA, Kouji YAMAMOTO, Seiji ISHIKAWA, Tan Joo KOOI, Reiji T ...
Article type: Article
Session ID: F-0807
Published: August 22, 2001
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To measure non-uniform strains over the ACL's entire surface for various knee angles, we used a motion capture technique and a method that allowed us to photograph the 3D deformations of the ACL. A cadaver knee was modified to expose its ACL for observation, and markers were glued onto the ACL along the macroscopically observed fiber bundle directions. The process begins with video of the ACL shape, recorded from multiple camera positions simultaneously without calibration for the camera orientations. Then the computer graphic images and animations for the 3D deformations of the ACL were made.
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Yutaka SAWAKI, Hidenori HIGASHI, Masataka TOKUDA, Kazuo YAGI, Tadashi ...
Article type: Article
Session ID: F-0808
Published: August 22, 2001
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Yuji MATSUZAKI, Masateru WATANABE, Tatsuya AOMATSU, Tadashige IKEDA, T ...
Article type: Article
Session ID: F-0809
Published: August 22, 2001
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In this study static pressures of unsteady airflow through a two-dimensional constricted channel are measured. The objective is to collect the data necessary for establishing a glottal flow model, which is indispensable for the analysis of vocal fold vibration as sound source of voice. In the measurement a rectangular block, a part of upper channel wall, is driven sinusoidally by a mechanical driving device which enables the block to vibrate in 100Hz, as high frequency as vocal fold vibration, and frequency dependence of static pressure is investigated over a range of 10-100Hz. The results show that the frequency strongly influences waveforms, amplitudes and phases of static pressures within and around the constriction. The influences on static pressure are found similar in the middle of the constriction (P(0)) and at its downstream (P(1)), while a different effect is observed on upstream static pressure. Findings obtained on P(0) and P(1) are that their amplitudes decrease greatly with increasing frequency in some frequency range, and that over a certain frequency a peak appears twice in one fundamental cycle of oscillatory static pressure.
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Yuji MATSUZAKI, Shinji DEGUCHI, Nobuhiro YAMAUCHI, Tadashige IKEDA
Article type: Article
Session ID: F-0810
Published: August 22, 2001
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In this paper the effect of the transglottal pressure on fundamental frequency of sustained voice is investigated using a two-dimensional flexible channel model of the vocal fold coupled with a one-dimensional unsteady flow model. The clinical measurement concerning this effect by other researchers shows that the mechanism involved in the vocal folds' vibration is different in a lower and a higher pitch range. We examine numerically the condition of mechanical properties of vocal folds which has the consistency with the experimental result. The result shows that there seems to exist a close relationship between the parameter values decided by numerical model and real larynx structure.
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Akihiko Nakamura, Yoshihiro Taki
Article type: Article
Session ID: F-0811
Published: August 22, 2001
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This is the study of the self-excited oscillations taking place in a flow of a collapsible tube such as a venular vessel or a natural rubber tube. In order to understand the mechanism, a one-dimensional simple model is used to formulate the strong interaction between the fluid and tube. The beam element is used for the longitudinal deformation of the tube and an experimental formula, tube law, is employed to evaluate the circumferential stiffness in the incremental forms. It is assumed that there is one dimensional incompressible flow with varying widths. The governing equation is expressed in the form of symmetric systems. Also, a stabilized method combined with the predictor multi-corrector algorithm is implemented. The mechanism and the relationship between pressure and deformation of the self-excited oscillation were shown in these computations of a simple model.
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Noriyoshi SUGA, Takuji ISHIKAWA, Nobuyoshi KAWABATA, Motoyoshi TATIBAN ...
Article type: Article
Session ID: F-0812
Published: August 22, 2001
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It is difficult for highly accurate methods such as CFD to model all blood circulation of the human body. In this research, bondgraph is used in order to simply model the all blood circulation of the human body, bondgraph is the effective method to express complicated systems and the computational load is small. The heart, the artery, the capillary, and the vein of human body are modeled by the bondgraph, and the change of flow rate and pressure are discussed.
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Hiroyuki HAYASHI, Takami YAMAGUCHI
Article type: Article
Session ID: F-0813
Published: August 22, 2001
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It is very important to elucidate the specific mechanism for the formation, growth, and breakdown of coronary plaque, in order to diagnose and to prevent ischemic heart disease, such as the myocardial infarction. In this study, a computational fluid dynamics using a simplified model of the right coronary artery, which deforms with contraction of the heart. The right coronary artery was modeled using an ordinary helix, whose torsion and curvature change in time with the contraction and dilatation of the heart. In the computational result, the flow in the model right coronary artery was thought to be more affected by the change of the curvature compared to that of the torsion.
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Masanori Nakamura, Shigeo Wada, Taisei Mikami, Akira Kitabatake, Takes ...
Article type: Article
Session ID: F-0814
Published: August 22, 2001
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Flow patterns in the human left ventricle (LV) during early diastole were studied theoretically by means of CFD using a 3-D model of the LV in order to find out the relationship between the diastolic flow pattern and the shape of the aliasing area which appears in a color M-mode Doppler echocardiogram. It was found that a vortex, asymmetrically enlarged on the side of the aortic valve, formed in the LV close to the mitral orifice, surrounding the mainflow that headed to the apex of the LV. The aliasing area that appeared in a color M-mode image obtained with CFD analysis was similar in shape to that obtained clinically. However, it did not agree quantitatively with that in clinically measured. It was considered that this was due to differences of size, birth place and developmental process of the vortex in the LV.
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Hidehito Iwase, Hao Liu, Shinichi Fujimoto, Ryutaro Himeno, Tomoaki Ha ...
Article type: Article
Session ID: F-0815
Published: August 22, 2001
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A 2 chamber-modeling method is developed to reconstruct an anatomic model of left ventricle based on B-mode ultrasound images for three-dimensional numerical analysis of heart hemodynamics. On a basis of the method we developed previously which utilizes multiple planar B-mode images obtained by flapping the probe of echocardiography along the heart centerline, we have further modified it to base our geometric model merely on two mutually vertical B-mode images of left ventricle with consideration of clinical application. The new method enables the implementation of speedup in the computational modeling and is easy for both user and patient. Some preliminary results are presented.
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B. V. Rathish Kumar, H. Liu, T. Yamaguchi, R. Himeno
Article type: Article
Session ID: F-0816
Published: August 22, 2001
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Computer simulation and visualization of haemodynamics in LV is of great clinical significance in treating patients with dilated cardiomyopathy. Numerical simulations that enable such graphical visualization are computationally very intensive. So in the current study we propose to discuss the parallel computation of LV flow dynamics on distributed memory based vector parallel processing system (VPP700) under UXP/VPPF90 environment. As a first case, we present the results pertaining to the parallel computation of 3D steady flow dynamics. Speedup and efficiency factors obtained by the present parallel computational strategy will also be presented.
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Yusuke KIMURA, Daisuke UJIHARA, Takami YAMAGUCHI
Article type: Article
Session ID: F-0817
Published: August 22, 2001
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The purpose of this study was to investigate the relationship between blood flow and atherosclerosis using Computational Fluid Dynamics. Atherosclerosis is suspected to be related to blood flow, since it develops at specific points on vessel walls. Among these specific locations, bifurcations of blood vessels are especially prone to atherosclerosis, particularly the lateral walls of the common iliac arteries. This distribution of lesions is believed to depend on fluid dynamics phenomena, particularly the wall shear stress. Due to the complex geometry of a real artery, the fine flow structure in an arterial bifurcation may be too complex to study using in vivo or in vitro experiments. Therefore, CFD is one of the most powerful ways to investigate flow in an arterial bifurcation. However, the relevant CFD model must be constructed to obtain a reliable computational analysis. In general, a bifurcation has a complex 3-D configuration, particularly at its sharp edge. Any minute deformation or relative displacement of the bifurcation is thought to have a significant effect on blood flow. In this study, a histology technique, in which the embedded vessels are sliced into thickness of the order of 1 micrometer, was used to model the arterial bifurcation. A computer was used to capture 2-D images of the face of the specimen block after each slice was removed. Then, serial images were used to reconstruct the 3-D blood vessel configuration with a precision appropriate for CFD analysis.
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Keisuke FUKUYAMA, Daisuke MORI, Tomoaki HAYASAKA, Takami YAMAGUCHI
Article type: Article
Session ID: F-0818
Published: August 22, 2001
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The three dimensional (3D) configuration of the arteries is very complex and this complex 3D geometry is considered to determine the distribution of mechanical forces exerted on the arterial wall by the blood flow. The 3D configuration of the aortic arch was modeled in the present study to analyze a single helical blood flow shown by clinical magnetic resonance imaging (MRI) studies. The single helical flow was thought to occur by a combination of the 3D distortion of the arch and the complex geometry of the major branches, and was thought to be responsible for the development of aortic aneurysms.
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Ryo TORII, Marie OSHIMA, Toshio KOBAYASHI, Kiyoshi TAKAGI, Nobuyuki TA ...
Article type: Article
Session ID: F-0819
Published: August 22, 2001
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This paper aims to estimate effect of elastic wall of blood vessel in the numerical simulation of blood flow. In order to future the internal carotid artery, the curved pipe model was used. The study was conducted using two different types of wall condition: 1) rigid wall, and 2) elastic wall. Instantaneous wall shear stress distributions and velocity distributions are compared between both cases. As a result, distributions and the maximum magnitude of wall shear stress are not different in both cases. The flow field is also similar and deformation of the wall is very small.
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Nami MATSUNAGA, Hao LIU, Ryutaro HIMENO
Article type: Article
Session ID: F-0820
Published: August 22, 2001
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Aiming at establishment of a method to solve blood flow in a Cartesian coordinate system by directly utilizing voxel data of medical images, we have developed a method to determine boundaries of a specific domain in a manner of VOF (fractional volume of fluid) and incorporated it into a NS solver. Some preliminary results are presented of oscillatory flow in a stenosed blood vessel, which show reasonable agreement with other results.
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Daisuke MORI, Takami YAMAGUCHI
Article type: Article
Session ID: F-0821
Published: August 22, 2001
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The human aortic arch has significant torsion in addition to its large curvature. It has pointed out that the torsion may be related to the development of the thoracic aneurysms. It is also known that the torsion affects the blood flow, which is suspected to be associated with various vascular diseases. In this study, a realistic three-dimensional computational fluid dynamics model of a human aortic arch was constructed based on a set of MR images and the blood flow in the arch was simulated. The results showed that the torsion of the aortic arch led to a complex localized distribution of the wall shear stress.
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Toshiro OHASHI, Shinji SEO, Takeo MATSUMOTO, Masaaki SATO
Article type: Article
Session ID: F-0822
Published: August 22, 2001
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A finite element analysis using structural optimization method was performed to simulate the remodeling of bovine aortic endothelial cells (BAECs), in which cell surface geometries were measured by an atomic force microscope (AFM) system. After applying a steady shear stress of 2 Pa for 24 hours, BAECs showed marked elongation and aligned in the flow direction. In the AFM measurements, the peak cell height decreased significantly from 2.8 ± 1.0 μm to 1.4 ± 0.5 μm with exposure to fluid flow. The fluorescent images showed that control cells exhibited dense peripheral bands of F-actin filaments, while sheared cells exhibited F-actin stress fibers which were thick and centrally located parallel to the flow direction. In the analysis, elastic modulus of each element was changed in accordance with an object stress, together with update of cell shape using Arbitrary Lagrangian-Eulerian (ALE) method. Numerical results showed that the cell height decreased with fluid flow and the higher elastic modulus appeared in the upstream region of the nucleus in the final step, which may correspond with cytoskeletal structure. The present analysis should be effective for clarifying the remodeling of endothelial cells.
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Shigetaka Fukuzaki, Shigeo Wada, Takeshi Karino
Article type: Article
Session ID: F-0823
Published: August 22, 2001
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In order to investigate the effects of hemodynamic factors on the development of vascular diseases such as atherosclerosis and intimal hyperplasia, we carried out a computer simulation of the change in the shape of the luminal surface of a stenosed artery by increasing the thickness of the wall step by step based on the distribution of wall shear stress which was obtained by the calculation for steady flow through the artery at each step to maintain the value of wall shear stress within a certain range. It was assumed that the blood vessel is thickened at the site where wall shear stress is lower than a certain threshold value and then the nodal points constituting the luminal surface of the vessel was shifted in the direction normal to the wall to correct the difference. As the results, it was found that intimal thickening progressed on both the proximal and distal sides of the stenosis where wall shear stresses were low in the stenosed artery at the initial state. However, the degree of the thickening was not determined directly from the value of the wall shear stress in the initial state but by the interaction of shape change of the artery and flow dynamics affected by it.
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Hiromasa SAWAZAKI, Takuji ISIKAWA, Nobuyoshi KAWABATA, Motoyoshi TACHI ...
Article type: Article
Session ID: F-0824
Published: August 22, 2001
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It is not appropriate to use constitutive equitions for small arteries because of the heterogeneity of the blood. In this paper, a new method to model an erythrocyte by using drag point s and springs is proposed as an altanative to analyze the blood flow. The behavior of erythrocytes is computed under Poiseuille flow. The rotating attitude of an erythrocyte under Poiseuille flow, shear-thinning property, first normal stress difference and plasma layer near the wall are discuassed.
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
Session ID: F-0825
Published: August 22, 2001
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Yusuke MORITA, Naohide TOMITA, Hideyuki AOKI, Shigeyuki WAKITANI, Yasu ...
Article type: Article
Session ID: F-0913
Published: August 22, 2001
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Mechanical properties of regenerated cartilage tissue were measured to evaluate change of visco-elastic properties during cultivation. Indentation test and dynamic visco-elastic measurement were carried out for rabbit articular cartilage inoculated in fibroin sponge. A 1.5mm-diameter porus indentor was used for the indentation test, where time-dependent strain curves were measured under several loading condition. Although amount of permanent deformation is not influenced by cartilage regeneration, the creep-behavior time constants are extended with cultivation days. The dynamic visco-elastic measurement was performed under compressive loading condition. The E' values increase with cultivation days and the peak value and frequency of tan δ shift to a lower amount. It is suggested that changes in time-dependent strain curves and dynamic visco-elastic properties of the regenerated cartilage are caused by synthesis of extracellular matrix and maturation of cultured cartilage tissue.
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Kazuo TAKAKUDA, Toimihisa Koyama, Hiroko Matsumoto, Hiroo MIYAIRI, Msa ...
Article type: Article
Session ID: F-0914
Published: August 22, 2001
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Experimental bone regeneration with the aid of bioabsorbable membrane was carried out for the cases of canine mandibular, tibia, and skull. The membrane was made of the composite of the copolymer of L-lactic acid, glycol acid and caprolactone and the inorganic material β-TCP. The experimental bone defects were covered by the membranes and the open spaces for the bone regeneration were realized. After 12 weeks of the operation, complete bone regeneration was observed in the case of mandibular. Partial regeneration in the cases of tibia and skull, in which cases the full regeneration was observed with the additional implantation of the bioabsorbable materials.
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Nobuyuki SHIBATA, Naohide TOMITA, Naoki ONMORI, Koji KATO, Ken IKEUCHI ...
Article type: Article
Session ID: F-0915
Published: August 22, 2001
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Recently, an explosive flaking-like destruction so-called delamination has been reported in retrieved ultra-high molecular weight polyethylene (UHMWPE) knee components. In order to investigate the effects of microscopic substructure such as grain boundaries, two-dimensional sliding fatigue tests were carried out for three types of UHMWPE samples, non-irradiated, gamma-irradiated, and vitamin E-added and gamma-irradiated samples. Morphology of sliding surface was examined by both SEM and an optical microscope. Surface roughness of the sliding surface was also measured. Our result showed that microscopic crack initiation and propagation was observed to occur at surface/subsurface grain boundaries of gamma-irradiated UHMWPE samples.
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Kazuhiro NAKASHIMA, [in Japanese], [in Japanese]
Article type: Article
Session ID: F-0916
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The hemi-arthroplasty is the arthroplasty by replacing one of articular surfaces in diseased natural joint to artificial component and recovers a function of the joint or releases from the pain for patients. In this study to simulate the hemi-arthroplasty, friction and wear for rubbing pair of PVA (polyvinyl alcohol) hydrogel and natural cartilage were evaluated in reciprocating wear tester by changing the lubricant. The lubricant containing protein reduced wear of the articular cartilage and the lubricant containing hyaluronic acid reduced wear of PVA hydrogel. The difference was observed in changing of protein type.
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Katsuko FURUKAWA, Mitsuhiro MATSUZAWA, Yasuyuki SAKAI, Junichi KOZASA, ...
Article type: Article
Session ID: F-0917
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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We developed a series of photoreactive biodegradable macromonomers consisting of caprolactone (CL) and lactic acid (LA). Four poly-(CL-LA) chains were synthesized from pentaerithilytol, and acrylyl radical groups were added to the end of these chains. Upon irradiation with UV or visible light, the macromonomers were successfully polymerized to form elastic materials with various shapes including macroporous cell supports. Young modulus and loss tangent were regulated by changing the length of the poly-(CL-LA) side chains. A material formed from a macromonomer with a molecular weight of 10,000 found to have young modulus and loss tangent close to those of native artery. Therefore, the developed new materials are useful for engineering a biohybrid-type blood vessel by inoculating endothelial, smooth muscle, or fibroblast cells.
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Kenzo ASAOKA, Masayuki KON, Tatsuro ARAKI, Akihide TOYAMA
Article type: Article
Session ID: F-0918
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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It is intended that proteins immobilize on the surface of titanium implants. This is accomplished by the porous titanium compacts and the precipitation of calcium phosphate on the surface of titanium because proteins can easily immobilize on the calcium phosphate crystals. Sintered compact both with biological functions of proteins and high strength as metals was developed. Three methods were applied to arrange the specimens. 1) The powders were sintered in the carbon dies to the shape by spark plasma sintering (SPS). After that, the compact was immersed in aqueous solution of CaO. 2) The powders were mixed with CaO particles, and sintered by SPS. 3) The powders were immersed in aqueous solution of CaO. The powders with surface modification were sintered by SPS. The compacts were then immersed in Hanks' solution. The amount of precipitation of the calcium phosphate in the compacts was measured and compared between the sintering methods. The sintered compact, which was titanium powder particles covered with calcium phosphate, could absorb large amount of proteins.
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Hironori SHIMIZU, Motoki TAKATA, Jun KOMOTORI
Article type: Article
Session ID: F-0919
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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To develop a new bio-implant material, it is very important to clarify a synergy among corrosion, wear, fatigue; corrosion is increased by the action of wear and fatigue. In this study, a new testing machine that can apply corrosion, wear and fatigue simultaneously was developed. Using this machine, the degradation of the bio-implant materials in-vivo can be estimated.
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Kiyomitsu MAEDA, Atsuhiko MORITA, Jun KOMOTORI
Article type: Article
Session ID: F-0920
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Titanium and its alloys are widely used as metallic biomaterials because of their high resistance to corrosion and biocompatibility. However, titanium ion is sometimes detected in tissues around titanium implants. The cause of ion release may be related to some kinds of organic species such as Macrophages. The aim of the present study is to clarify the effect of the existence of Macrophages on corrosion response of metallic implants. Immersion tests of highly polished SUS316 disks were carried out using 4 types of medium; RPMI1640+FBS(solution A), RPMI1640+FBS+U937(solution B),RPMI1640+FBS+Macrophages(solution C) and Ringers solution (solution D). All tests were performed at 37℃ in normal environment with 5% CO_2 added. To measure the corrosion rate, electrochemical tests were also carried out.
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Kenichi NAKATA, Yusuke MORITA, Hideyuki YOSHIDA, Ken IKEUCHI
Article type: Article
Session ID: F-0921
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Though strength and toughness of zirconia are high, the wear factor of zirconia/zirconia was larger than that of alumina/alumina in the previous study. However it is considered that changing combinations of materials improve wear properties. Therefore we investigated the wear properties of zirconia/alumina combinations for artificial joint, using end-face apparatus. Bovine serum solution was used as lubrication. Contact pressures were 5 MPa and 10 MPa. Sliding velocity was 40 mm/s, and sliding distance was 10 km. In this study, total wear factor of zirconia/alumina was much less than that of zirconia/zirconia.
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Yoshinori SAWAE, Teruo MURAKAMI, Shuhei YOSHIDA, Changhee CHO, Takatos ...
Article type: Article
Session ID: F-0922
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The two-channel knee joint simulator was developed to evaluate the wear behavior of total knee prostheses, and effects of the femoral component material on the wear behavior of the polyethylene tibial insert were examined. The knee joint simulator used in this study has three servomotors and two hydraulic actuators to reproduce the walking conditions of the knee joint. In this study, the typical flexion-extension angle and tibial axis load of an adult American male were used. The two dimensional contact analysis was performed by using FEM software to decide the anterior-posterior movement suitable to the surface geometry of the knee joint specimen and to prevent the artificial contact condition. The actual contact condition between the femoral and the tibial component was examined experimentally by using the tactile sensor and results were compared with the analytical prediction. The wear behavior of the polyethylene insert was estimated from the weight change, however, significant difference could not be identified between the Co-Cr femoral component and the alumina femoral component.
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Changhee CHO, Teruo MURAKAMI, Yoshinori SAWAE, Hiromasa MIURA, Tsutomu ...
Article type: Article
Session ID: F-0923
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The wear phenomenon of UHMWPE in the knee and hip prostheses is one of the major restriction factors on the longevity of these implants. Especially in retrieved knee prostheses with anatomical design, the most predominant types of wear on UHMWPE tibial components are pitting and delamination. These fatigue wear of UHMWPE are believed to result from the repeated plastic deformation due to high contact stresses. In this study, elasto-plastic contact analysis of the UHMWPE tibial component based on geometrical measurement for retrieved knee prosthesis was performed using FEM to investigate the plastic deformation behavior in the UHMWPE tibial component. The results suggest that the maximum plastic strain below the surface is closely related to the subsurface crack initiation and, by extension, delamination of UHMWPE.
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Hiroki KAWASHIMA, Ko TAKANO, Kazuhiro HASEGAWA, Toshiaki HARA
Article type: Article
Session ID: F-0924
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The goal of this in vitro study was to investigate the initial mechanical state of the lumher functional spinal unit (FSU) with three types of spinal fixation devices. An experimental porcine FSU testing system was developed for the in vitro motion measurement during flexion-extension, lateral bending and axial rotation. Three groups of FSU (L1/2,3/4,5/6) with each system of Hokkaido Hook and Rod (HHR), Graf and Global were tested. These initial lumber stabilization states were compared on the basis of stiffness and mechanical characteristics during FSU motions. The dominate result of the study were that the mean stiffness in the HHR system decreased significantly when compared to those in both Graf and Global systems, and that the mean neutral zone was visibly wide.
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Takuma HIGA, Shunji HIROKAWA, Nobuo OHTSUKI
Article type: Article
Session ID: F-0925
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Although such functions as Bezier, B-Spline and NURBS are widely used in Computer Graphics for generating any free-formed surfaces, they are not necessarily appropriate for describing the existing surfaces; they need structured data sets according to a grid. Their mathematical structures (the patch methods) make it almost impossible to obtain entirely smooth surface. To overcome these problems, an application of parameterized polynomial functions was proposed in this study. By using our parameterized polynomial, the artificial knee joint surface was described mathematically and the results were fully compared with those from B-Spline in terms of accuracy and smoothness.
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Norio INOU, Michihiko KOSEKI, Mitsuhiro IWASAKI, Koutaro MAKI
Article type: Article
Session ID: F-0926
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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This study adresses a new interpolation method for generating a finite element model from CT or MRI images of an object taken at equal spaces. The method consists of 4 steps. First, horizontal contour images of the object was extracted from the sliced images. Second, vertical contour curves are interpolated from the sliced images. Third, the continuous shape of the object is generated by use of these contour data. Finally, CT values between sliced data are interpolated by the shape data. This paper shows that the method performs a clear interpolation compared with a simple linear interpolation method.
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Kazuhiro Matsuda, Ikuya Nisimura, Hiromasa Tanino, Masaru Higa, Yosino ...
Article type: Article
Session ID: F-0927
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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Loosening of cemented femoral hip stems could be initiated by failure of the cement mantle due to high cement stress. This report describes static analysis of stress in the bone cement mantle, Design Sensitivity Analysis (DSA), and the three dimensional shape optimization of cemented femoral hip stems. This study analyzed stresses in the cement mantle, using a three-dimensional p-adaptive finite element method based on 3D CAD model. The p-methods and 3D CAD based model made an exact modeling possible. The results of the design optimization showed considerable reduction in stress concentrations in the cement mantle compared to the default design.
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Kazunori UEKI, Toshio WATANABE, Masaaki NEGISHI, Yuko Sano, Toshiaki H ...
Article type: Article
Session ID: F-0928
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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In this paper, the stress characteristics of dental prosthesis were analyzed to study effects of mechanical human oral conditions. Finite element method was used to analyze for 3D dental bridge model. 3D models were constructed by 3D CAD system and modeling software developed for dental technology. Mechanical conditions were set biting strength loaded for facies occlusalis and abutment tooth constrained taken into account incompatibility and loosening between prosthesis and natural tooth. It was found from the results that von mises stress at the part of connecting bridge model was increased with more misfit conditions. The results showed that incompatibility and loosening of the dental bridge generated larger stress and that the case accounted for dental bridge fracture.
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Sagiri HORISAWA, Hiromu HASHIMOTO, Hideo YOKOTA, Sakiko NAKAMURA, Akit ...
Article type: Article
Session ID: F-0929
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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This paper describes the three-dimensional observation of morphology of flight muscles in some kinds of winged insects such as bees, dragonflies, and cicadae. In the 3-D observation of flight muscles, sequential sections through thoraces are sliced at the thickness of 30μm by the rotating knife and taken photos by camera with three-dimensional internal structure microscope automatically and repeatedly. Moreover, the 3-D images can be reconstructed by a computer based on the digital data after recording. Therefore, it is possible to observe any sections of thoraces, which have not actually been slices. From the 3-D observation, it is confirmed that the winged insects can be classified into three groups at least by the differences of morphology of flight muscles.
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Sagiri HORISAWA, Hiromu HASHIMOTO
Article type: Article
Session ID: F-0930
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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The aim of this second paper is to elucidate the relation between morphology of flight muscles and function of wings. The paper describes two experiments: measuring the structural characteristics of thoracic exoskeleton in the indirect-flight-muscle type of insects and the vibration characteristics of wing in the direct-flight-muscle type of insects. In the indirect-flight-muscle type of insects, the deflections of thoracic exoskeleton are measured under the static load. As results, the obtained load-deflection diagrams show linear relation between them. In the direct-flight-muscle type of insects, the ultra high speed video camera is used to record the wing motion under the free flight conditions by making use of their nature of high sensitivity to light. The frequencies of wing vibration are determined from the analyses of recorded data on videotapes. It is found that the vibration frequencies depend on the wing mass in the case of losing weight and independent on it in the case of gaining weight.
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Hideki SAITO, Koji KOMAZAWA, Yoshiyuki MIWA, Yasuhiro KUSHIHASHI
Article type: Article
Session ID: F-0931
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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In order to investigate how root communicates with each other by the electric field, a root-mimetic device which generates electric field has been developed. The system is comprised by subunits such as (1) three carbon-tip electrodes, (2) a voltage source subunit which enables changing level and formation of source and sink by using analog multi-plexers and D/A converters, (3) Z-80 microprocessor as a local controller and (4) a computer which controls whole system through optical-isolated serial line. Consequently, it was shown that generated patterns of electric field by our system were similar to ones by infant root and that electric field formed around root changed by applying the system. Finally, effectiveness of the system was confirmed.
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Ayumi MITOH, Yohichiro KOJIMA, Eiji SOBU, Isao TAJIMA
Article type: Article
Session ID: F-0932
Published: August 22, 2001
Released on J-STAGE: August 01, 2017
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This paper deals with a kind of soft machine based on gel actuator system. The actuator consists of polyvinyl alcohol (PVA) gel mixed with magnetic fluid. We called it magnetic gel actuator. PVA gel has visco-elastic properties like a human muscle. In this paper, characteristic of the magnetic gel actuator is measured against static magnetic field. As the result, PVA gel had viscosity about 0.1 Pa・s at room temperature. And the magnetic gel actuator could resist against 780Pa when a magnet (0.36T) got closer to it. Furthermore it could rise up and down weights from 5 to lOOg. There is shown the possibility that magnetic gel actuator can become new soft machine actuator like muscle, bowel and so on.
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