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Article type: Cover
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Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Article type: Appendix
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App1-
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Article type: Index
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Toc1-
Published: August 05, 2003
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Taiji ADACHI, Hiromichi KUNIMOTO, Yoshihiro TOMITA
Article type: Article
Pages
1-2
Published: August 05, 2003
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Using a voxel finite element method that allows us to integrate modeling and analysis of a complicated three-dimensional structure, a new numerical method for shape optimization problem was proposed here based on the traction method. A minimization problem of stress nonuniformity in the domain was formulated for a three-dimensional linear elastic structure. In this method, a domain variation that was obtained as a velocity field from a shape gradient function was accomplished by removal and addition of the voxel elements on the domain surface. A case study for cantilevers subjected to uniformly distributed forces demonstrated that the minimization of the stress nonuniformity was achieved by changing the domain shape. In addition, a possibility of the topological change as well as shape change was suggested using the proposed method.
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Yoshihisa MINAKUCHI, Akira YAMAGUCHI, Horiuchi TADAHIRO
Article type: Article
Pages
3-4
Published: August 05, 2003
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We investigated the healing behavior of the bone in plate fixation for a diaphysis fracture using growth strain method. The growth criterion parameters of each cortical bone and callus were determined on normal diaphysis bone by applying two-dimensional finite element method. Next, the remodeling shape on the diaphysis fracture fixed by a plate with 4 screws was created using the growth criterion parameters on the strain energy density. Our findings showed that the periphery of diaphysis fracture swelled after cure. Then, it was the best operation method which penetrated the screws to the cortical bone perfectly.
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Jiro SAKAMOTO, Juhachi ODA, Sigeharu KIMURA, Takahiro KOZAKI
Article type: Article
Pages
5-6
Published: August 05, 2003
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Visible Human images provided useful information for research of biomechanics, especially for making computational musculoskeletal model and its analysis, because geometrical data of bone and muscle are given by the images. Although some musculoskeletal models based on the Visible Human were developed and analyzed, data format of the musculoskeletal models were not open for general use and depended on computer program developed by each researcher. We developed a musculoskeletal model of upper-limbs based on the Visible Human for SIMM (Musculo Graphics Inc.), which is general-purpose program of musculoskeletal simulation. The musculoskeletal model was applied to the muscle force analysis of upper-limbs with Kinesio tape, and its biomechanical effect was discussed.
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Yoshiyuki SATO, Tomofumi SASAKI, Hidemi ITOH, Toshiro OHASHI, Masaaki ...
Article type: Article
Pages
7-8
Published: August 05, 2003
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Finite element analysis was performed on mandibular bone with distal extension removable partial denture (RPD) to assess the effects of RPD on stress distributions in mandibular bone. A finite element model was generated using X-ray CT data on the plaster model having the same morphology as the mandibular model, in which the mechanical properties of mandibular bone, natural teeth and RPD were assigned. In the analyses, a vertical loading was applied to the first molar to approximate occlusal loading of teeth. The analytical results showed the high stress concentrations in the distal and apical side around the first premolar. The present method should be effective for designing distal extension RPD.
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Yoshimi OMURA, Jiro SAKAMOTO, Daisuke TAWARA, Juhachi ODA
Article type: Article
Pages
9-10
Published: August 05, 2003
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Size and shape of bone depend on age, sex and individual difference. Furthermore, shape of a bone is change in long term due to growing, aging, or affection. Recently, patient oriented analysis has been required in biomechanical study from the viewpoint of tailor medicines, so procedure to make individual bone model is developing based on CT images taken from the patient. The modeling method based on CT images expend much hours and very costly. In this study, basis vector method, which is often used in the structural optimization area, is applied to make individual bone model efficiently. Various shape model can be created by composition between existing basis models in the method. It is applied to change the shape of vertebra, and effectiveness of the method is discussed.
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Nobuhiro YOSHIKAWA, Osamu KUWAZURU, Yoichi NAKAMOTO
Article type: Article
Pages
11-12
Published: August 05, 2003
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A non-invasive material testing methodology is investigated for the purpose of material modeling of biological soft tissue in finite element analysis of human body. An identification method of in vivo displacement field is developed as first step of the investigation. Two kinds of voxel models are constructed for initial and loaded body by means of newly developed experimental system with X-ray CT. We pose an identification problem of a mapping function from the original state to deformed one. The initial voxel model is transformed via the mapping function in the form of the Fourier series with tentatively determined coefficients. An error function is evaluated as square-sum of deference between pixel values assigned to voxels at the same position of actually loaded and virtually transformed voxel models. The optimum values of the coefficients are searched for via SCE-UA method (Shuffled Complex Evolution Method Developed at the University of Arizona), since the pixel value is integer and the positions of error evaluation are discrete. An experiment using inhomogeneous specimen demonstrates a validity of the proposed method.
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Aki YAMAUCHI, Masakazu KUME, Toshio TSUTA, Takeshi IWAMOTO
Article type: Article
Pages
13-14
Published: August 05, 2003
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Takanori KONNO, Yasukazu NISHI, Kazuyoshi HOSHINO, Toshikatsu OTANI, R ...
Article type: Article
Pages
15-16
Published: August 05, 2003
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The use of the ultrasound-imaging platform in medical facilities has significantly increased in recent years due to its superior capability, namely high resolution, small influence to the human body and so on. Though the doctors diagnose a tissue characterization of a liver by observing an image obtained by ultrasound, a diagnostic result seems to make a difference with experience of doctors. Therefore a quantitative analysis method concerning ultrasonography is required. This paper proposes a CAD by a neural network, which diagnoses a tissue characterization of liver. This system studies three kinds of teacher signal (conditions of liver : normal, chronic hepatitis and liver cirrhosis). As a result, this system is confirmed that it can distinguish between normal of liver and liver cirrhosis. In addition, auto optimization causes the adverse effect for the discriminate accuracy. Our future purpose is the discriminate accuracy improved by increasing the number of teacher signal.
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Yuki OGIHARA, Yasukazu NISHI, Takuji SAKAI, Kazuyoshi HOSHINO, Toshika ...
Article type: Article
Pages
17-18
Published: August 05, 2003
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The use of the ultrasound-imaging platform in medical facilities has significantly increased in recent years due to its superior capability, namely high resolution, small influence to the human body and so on. Though the doctors diagnose a tissue characterization of a liver by observing an image obtained by ultrasound, a diagnostic result seems to make a difference with experience of doctors. Therefore a quantitative analysis method concerning ultrasonography is required. This paper proposes a CAD by an expert system, which has two mechanisms of estimation (Type I : inside roughness, Type II : edge angle). After the effectiveness of Type I and II are confirmed respectively, an estimation combined with two Types is applied to three kinds of the condition of the liver, namely normal, chronic hepatitis and liver cirrhosis. As a result, three conditions are exactly recognized and our proposed system is suitable for estimating the tissue characterization of the liver.
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Marie OSHIMA, Hiroshi SAKAI, Kiyoshi Takagi
Article type: Article
Pages
19-20
Published: August 05, 2003
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The Image-Based Simulation is a promising method to examine blood flow in the artery for investigation of the relationship between cardiovascular diseases or cerebrovascular disorders and hemodynamics. In general, the image-based simulation is performed for a particular region where the disease tends to occur so as to obtain solutions within reasonable computational time. The authors have been engaged in the image-based simulation for blood flow in the cerebral arties and aneurysms in order to understand the mechanism of creation, growth, and rupture of aneurysm. Thus, it is important to include the influence of entire vascular network system over the designated region. In order to achieve this purpose, the paper develops the boundary condition model based on the anatomical geometry of cereborvascular geometry. The simulation was conducted to examine the applicability of the present method.
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Tomohiro FUKUI, Kenichi TSUBOTA, Shigeo WADA, Takami YAMAGUCHI
Article type: Article
Pages
21-22
Published: August 05, 2003
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Pulse Wave Velocity (PWV) is a very useful index for the systemic assessment of the cardio vascular diseases. To explore more effective usage of the PWV for the localized diseases, we analyzed the fluid-solid coupled problem of the stenosed artery with various area reductions ranging from 0% to 50% by using our application software. It was assumed that the stenosed artery is axisymmetric and the shape of the stenosis is given as the Gaussian curve. It was found that the PWV of the stenosed artery increases with the increase of the severity of the stenosis and the difference of the PWV between the stenosed and straight arteries reached 0.9m/s for the stenosed artery with an area reduction of 50%.
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Takashi OGAWA, Hisato MINAGAWA, Yasunari TAKANO
Article type: Article
Pages
23-24
Published: August 05, 2003
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Velocity measurements for flows in a capillary tube of the inner diameter of 50μm and the length of 200mm have been conducted using a fused silica capillary tube connected with a syringe pump. Numerical simulations have been carried out to be compared with the experiments employing a one-dimensional fluid dynamic model in an elastic tube.
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Yohsuke IMAI, Takayuki Aoki, Tetsuya Kobara
Article type: Article
Pages
25-26
Published: August 05, 2003
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The computer simulation for blood flows interacting with elastic vessel requires a new numerical scheme. The INTERGRID method on the Cartesian grid has been developed based on the combination of original Cut-Cell technique and IDO (Interpolated Differential Operator) scheme. DEM (Discrete Element Method) is employed for modeling of the elastic vessel and coupled with the fluid equation. In comparison with the case with the rigid vessel, the maximum pressure decreases, and the response of the flow velocity for the pulsatile injection is delayed owing to expanding the blood volume.
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Ryo TORII, Marie OSHIMA, Toshio KOBAYASHI, Kiyoshi TAKAGI
Article type: Article
Pages
27-28
Published: August 05, 2003
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Image-based numerical fluid-structure interaction analyses are performed to investigate the relationship between hemodynamic force, which is known to affect vascular diseases, and stress in arterial wall. Tensile stress in aneurysmal wall is calculated near bleb, which is said to be one of risk factor of rupture of aneurysm. The relationship between hemodynamic force on and stress in aneurysmal wall obtained in this study can explain the process of rupture of aneurysm.
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Kensuke Yokoi, Hao Liu, Kazuaki Fukasaku, Ryutaro Himeno
Article type: Article
Pages
29-30
Published: August 05, 2003
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We propose a numerical method for blood flows in the complex vessel. The method is based on the fractional step method, the CIP method, the level set method and the ghost fluid method. We applied the method to blood flows in cerebral artery with five aneurysms.
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Makoto HARAZAWA, Kenichi TSUBOTA, Shigeo WADA, Takami YAMAGUCHI
Article type: Article
Pages
31-32
Published: August 05, 2003
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The blood flow regulation of the circle of Willis is thought to have a close correlation with the anatomy of the circle. In this study, we performed the computational fluid dynamics simulation with three-dimensional model in order to consider the relationship between the cerebral blood flow and the geometric configuration of blood vessels. The decrease of blood flow at the left internal carotid artery (LICA) led to the greater reduction of the blood flow at the left middle cerebral artery (LMCA) and the left anterior cerebral artery (LACA) which are near the LICA, and led to the smaller reduction at the left posterior artery (LPCA) and the blood vessels on the right side of the circle which are far from the LICA. Furthermore, the decrease of blood flow at the basilar artery (BA) led to the greater reduction of the blood flow at the left and right PCAs which are near the BA, and led to the smaller reduction at the MCAs and ACAs which are far from the BA. These results indicate that the redistribution of the blood flow in the circle of Willis is affected by the configuration, such as the spatial proximity of the blood vessels.
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Hidehito Iwase, Hao Liu, Kazuaki Fukasaku, Ryutaro Himeno
Article type: Article
Pages
33-34
Published: August 05, 2003
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This paper aims to simulate hemodynamics in cerebral artery netowrk like Circle Willis artery in which cerebral aneuryms occure frequent by using computational fluid dynamic (CFD). Since anatomic topology and geometry in the cerebral artery network is of great complexity and hereby we propose an efficient method in construction of realistic anatomic geometric model of the cerebral artery network system by means of using CAD tool.
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Kazuki EGUCHI, Daisuke MORI, Kenichi TSUBOTA, Shigeo WADA, Takami YAMA ...
Article type: Article
Pages
35-36
Published: August 05, 2003
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It is suggested that initiation and growth of an aortic aneurysm is related to the flow induced wall shear stress (WSS). The blood flow in the aorta with an aneurysm is affected not only by the geometry of the original aorta but also by the shape, location, size of the aneurysm. In this study, we constructed various CFD models of the aortic aneurysm by combining a three dimensionally bended aorta with an aneurysm whose shape is expressed as a two dimensional Gausian function. It was found that the location of the high wall shear stress region is discontinuously changed from upstream to downstream of the aneurysm by changing the size and location of the aneurysm.
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Masahiro WATANABE, Teruo MATSUZAWA
Article type: Article
Pages
37-38
Published: August 05, 2003
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In this report, the 3D shape was extracted from the image for medical treatment of the artery bow, and simulated by finite volume method. First, the technique to extract the blood vessel shape in accuracy was examined. The Marching cubes algorithm was used for the construction of the 3D shape from the CT images. The generated model for simulation had 100829 volume meshes. The changing flow was assumed to be a boundary condition of the entire. The numerical simulation was done, and the wall pressure and wall shear stress were examined.
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Daisuke MORI, Kenichi Tsubota, Shigeo Wada, Takami Yamaguchi
Article type: Article
Pages
39-40
Published: August 05, 2003
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It has been suggested that the development of aneurysms in the thoracic aorta is closely related to the torsion of the aortic arch. In this study, we analyzed flow in aortic arch models with various torsions using computational fluid dynamics simulation. The correlation between the aneurysm of the thoracic aorta and distortion of the arch was investigated from a fluid dynamics point of view. It was observed that the global feature of the secondary flow pattern, and the wall shear stress (WSS) distribution did not depend on the torsion of the arch from the qualitative viewpoint. However, the quantitative value of WSS appeared to be affected by the torsion. It was shown that WSS tends to increase when the torsion of the aortic arch increases. This result suggests that distortion of the aortic arch strongly influences WSS distribution, which is suspected to be related to the development of vascular diseases.
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Tatsuo TAKANO, Nobuatsu TANAKA, Masaru IWATA, Yasunori MOTOYAMA
Article type: Article
Pages
41-42
Published: August 05, 2003
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We have developed a microscopic blood model based on the SPH method. In the method, plasma fluid is discretized into SPH particles and an erythrocyte is modeled by internal fluid particles wrapped in elastic membrane particles. For verifying the model, the erythrocyte behavior under constant shear field (tank tread motion) is numerically analyzed. With the method, the tank tread motion of erythrocyte is well reproduced.
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Toshio NAKAYAMA, Masahiro WATANABE, Shigeru ISHIKAWA, Teruo MATSUZAWA
Article type: Article
Pages
43-44
Published: August 05, 2003
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We reported that the modeling of the 3-dimensional calculation model of a human nasal cavity was performed based on CT image of a nasal cavity. The modeling is to build from 106 slice images of TIFF formatted and smoothing the surface. After we simulated the flow of the breath in both nasal cavities using the built model using a FEM commercial code, PAM-FLOW. In this paper we show the result of numerical calculation done by the research that we had done were examined.
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Takuji KOIKE, Kazuaki KONNO, Hiroshi WADA
Article type: Article
Pages
45-46
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The size and mobility of the middle ear are different between individuals, and the effects of these differences on the middle ear transfer function have not been clarified. In this study, using finite-element middle-ear models, the effects of individual differences in size and mechanical properties of the middle ear on its transmission characteristics were analyzed. The individual differences in size of the middle ear were found to affect the transfer function, and the effects of size of the tympanic membrane were more remarkable than those of the ossicles. The effects of Young's modulus of the ligaments and tendons on the transfer function were significantly large compared to that of the size. It was suggested that the differences of each part of the middle ear independently affects the transfer function.
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Hiroshi ISHIGURO, Hirokazu IMAI, Noriaki SUZUKI
Article type: Article
Pages
47-48
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Behavior of ice crystals and cells in the biological tissues during the slow-warming after rapid-cooling was investigated microscopically in time-series using a confocal laser scanning microscope with a fluorescent dye. Attention was paid on the recrystallization of intracellular ice crystals to increase the mechanical damage of the tissues. Size and number of the ice crystals were measured from the image-data of ice crystals and statistically analyzed to obtain frequency, average, and standard deviation of the size of ice crystals, total amount and number density of ice crystals, etc. in time-series. Influence of the aqueous solution (influence of the additive to the physiological saline) on these characteristics was made clear.
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Yukio TADA, Akira TAKIMOTO, Yoshiaki ISHII, Yujiro HAYASHI
Article type: Article
Pages
49-50
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The accurate prediction of intracellular ice formation in biological cell is greatly important for determining life-death of living cell. In this paper, by combining the artificial biomembrane and two chamber as intra- and extra-cell, simplified biological cell was simulated. As biomembrane, phospholipid bilayer formed by folding technique was used. Summarizing experimental results, the barrier effects of cell membrane foe seeding by extracellular ice was clarified in conjunction with the following parameters; cryoprotectant in extra- and intra-cell, space between phospholipid molecules, and osmotic stress.
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Junpei HARADA, Kentaro UCHIDA, Megumi BITOH, Masanobu UJIHIRA
Article type: Article
Pages
51-52
Published: August 05, 2003
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The effect of area cell density on the post-thaw viability of cells in cryopreserved monolayer cells was studied. Human fibroblasts were two-dimensionally cultured for 1 day in a culture dish (Φ35mm). Different cell densities for the artificial tissue were used, from 2×(10)^3 to 5×(10)^4 cells/(cm)^2. Cultured monolayer cells was first stacked in a test chamber (Φ35×12mm), then frozen at a cooling rate of 0.3 to 30℃/min from 4 to-80℃ in a solution of Dulbecco's Modified Eagle Medium, 20% Fetal Bovine Serum, and 10% dimethylsulfoxide, then cooled down to -160℃ and lower, and finally thawed. Monolayer cells were suspended using trypsin. Post-thaw viability of fibroblasts was evaluated by using a trypan blue exclusion assay. Results show that with increasing area cell density, the post-thaw viability decreased, and contact of the cells was observed. Contact of the cells may induce intracellular freezing or give mechanical stress to a cell during freezing, and therefore the post-thaw viability seems to decrease.
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Manabu TAKAHASHI, XHA Zhu, Nagatoshi OKABE, Shinfuku NOMURA, Kenji AND ...
Article type: Article
Pages
53-54
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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To execute surgical operations on livers in short time and to reduce the stress on the patients, we propose a soft freezing method for liver surgical procedures. In this surgical procedure, a tumor surrounding the liver is frozen in order to ease the excision and prevent hemorrhage. The effects of cooling velocity and freezing temperation on the excision force by the scalpel on the liver are carried out experimentally as a basic research into partial freezing surgical procedures. In this study, to excise a cancer using free excision curve, the development of the cooling needle and the investigation of the cooling function were carried out using a liver of a pig. The physical properties value was reversely analyzed by using the finite element method based on the heat transfer characteristic data of a mock liver. In addition, the proposed estimation equation can express the relation between arbitrary cooling time and distance and temperature.
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Takao NAGASAKI, Junya Fujita, Yutaka ITO, Hiroshi ISHIGURO
Article type: Article
Pages
55-56
Published: August 05, 2003
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A numerical method to simulate the freezing process in cryosurgery has been developed. The unsteady three-dimensional heat conduction and phase change were solved in a Cartesian grid system by using an enthalpy method. A cut cell method was used to deal with the cylindrical probe placed in the Cartesian grid. Heat conduction along the wall of cryoprobe was also solved in a cylindrical grid fixed on the probe. It was shown that the present method predicts the growth of iceball correctly with relatively coarse grid for various inclination of the probe.
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Shimfuku NOMURA, Tunehiro MAEHARA, Yuuji WATANABE, Kanji KAWATI, Kenit ...
Article type: Article
Pages
57-58
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The purpose of this report is to investigate the heating effect of agar phantom containing ferrite powder by applying external AC magnetic field. Mg ferrite is most applicable for local hyperthermia. When using AC magnetic field with a frequency of 190 to 700kHz, the higher the frequency can increase the temperature of agarphantom containing 3.0 and 5.0% Mg ferrite powder. Even to the same weight of ferrite powder, the lager heat generation is obtained at the larger powder size. Moreover, a slight difference of distribution of ferrite powder has marked effects on the maximum temperature in vivo.
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Toshitsugu HARA, Jun NAGAYA
Article type: Article
Pages
59-60
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Temperature change of human hand was measured experimentally in order to calculate heat transfer rate to main body with circulating blood flow. The human hand was heated by a radiation panel heater and was measured temperature distribution by an infrared camera. Gloves in which water or water solution was contained inside corresponding to a bloodless hand were also heated and measured by the same way. Temperature of human hand increased and gradually tended to a constant temperature while temperature of gloves contained water solutions increased continuously. The heat transfer between hand and body was calculated from the difference between temperature of hand and glove.
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Ryuta Ibuki, Shigenao Maruyama, Seigo Sakai, Behnia Masud
Article type: Article
Pages
61-62
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A novel concept for a thermoelectric actuator comprised of shape memory alloy (SMA) and Peltier elements has been proposed. The SMA is heated and coled effectively by Peltier elements allowing quick movement to be achieved. The thermoelectric actuator has potential applications to an implanted artificial heart muscle. Moving performance of artificial heart muscle is numerically calculated with considering about heat damage to human tissue in case that utilized in human body as practical usage.
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Masaki FUCHIWAKI, Kazuhiro TANAKA, Shingo Sewa, Kazuo Onishi
Article type: Article
Pages
63-64
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We have proposed the flow control by using an artificial muscle based on the conducting polymer. In order to utilize the artificial muscle for flow control, it is important to clarify the mechanical properties on the artificial muscle based on the conducting polymer. The purpose of this study is to clarify the mechanical properties on artificial muscle and possibility of flow control by using it. We have measured the tensile force generated by artificial muscle in the distilled water. Moreover, we have observed the actuation of artificial muscle based on the conducting polymer in water tunnel. The tensile force of artificial muscle increased as the electrode potential increased. The averaged maximum tensile force did not depend on the scan rate of electrode potential. It depended on the electrode potential and was almost constant. However, the time for reaching maximum tensile force depended on the scan rate. The artificial muscle performed the bending actuation sufficiently not only static water but also running water. Therefore, it can be considered that the artificial muscle will be applied to the actuator for flow control.
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Yuichi NAKAMURA, Naoto KAKUTA, Yukio YAMADA
Article type: Article
Pages
65-66
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Water as well as wastes is removed from the blood of patients under dialysis treatment. If the quantity of the removed water exceeds the limit by some reasons the probability of dangerous accidents becomes high. Therefore, it is highly desired to monitor the blood status continuously during dialysis treatment. This paper presents some results of a fundamental research of measurement of water content in blood using near infrared spectroscopy and multivariate analysis for the purpose of continuous blood monitoring.
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Atushi NAKANO, Yasuhiko SUGII, Motomu MINAMIYAMA, Shigeru NISHIO, Hide ...
Article type: Article
Pages
67-68
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A novel technique using particle image velocimetry (PIV) was developed to evaluate the detailed velocity profiles of red cells flowing in microvessels. Based on the digital high-speed video-microscopic images, detailed velocity profiles at branching and confluence arterioles were analyzed with 0.8μm in the spatial resolution and 1 msec in the time interval. At the branching arteriole, the centerline velocity of proximal vessel was decreased markedly near the apex, and the cross-sectional red cell velocity profile showed double peaks. However at a distal of confluence, the centerline velocity was not observed the incensement and the double peaks profile, as symmetric to the branching. These red cell flow profiles suggests that the shear-stress acting to the endothelium were much affected by the microvascular geometries.
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Nobuhiko NAKAZAWA, Akihiro TORISU, Susumu KUDO, Ryuhei YAMAGUCHI, Hiro ...
Article type: Article
Pages
69-70
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In the present paper, the change of flow structure such as the wall shear stress at the apex of the anterior communicating artery with the initiation of aneurysm is described in steady flow. The anterior communicating artery composing the circle of Willis is one of the predilection sites where the cerebral aneurysm occurs frequently. The velocity profile is clarified around the apex where the cerebral aneurysm is apt to initiate. In particular, the gradient of wall shear stress around the apex at one confluent tube with much flow rate is estimated, and the relation between the change of wall shear stress, the initiation and the development of aneurysm is discussed physiologically.
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Yutaka FUKUZAWA, Shunichi KOBAYASHI, Hirohisa MORIKAWA, Daisuke TSUNOD ...
Article type: Article
Pages
71-72
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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There are complicated forces involved in the stenosis, which may causes the atherosclerotic plaque fracture. The increase in blood flow velocity in the post stenosis causes negative transmural pressure, which may compress the plaque to collapse. We used experimental stenosis models that closely approximate the arterial disease situation where the entire stenosis is compliant. This paper was examine the influence of curvature and stretch of the stenosis on flow and collapse under pulsatile flow.
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Tsutomu TAJIKAWA, Kenkichi OHBA, Hironori Nakamura
Article type: Article
Pages
73-74
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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It has frequently happened in a complicated flow field passage of the blood especially in an inner curved part of an aortic arch that a disease of the blood vessel breaks out by hardening of the arteries. Therefore it is important to make clear distribution of the velocity in human aortic arch. Therefore we made a 3 dimensional realistic model of aortic arch using reconstructed volume data with use of Visible Human Project dataset. The volume image showed that thoracic aorta had very little torsion and angle between ascending aorta and thoracic aorta was significantly. In order to study the influence of the deflection vessel, the velocity profiles in the 3D aortic arch model, which was based on VHP data, was visualized and measured by using PIV and LDV on the steady flow condition and pulsatile flow condition.
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Shigeru TADA, Tomoyuki HATAKEYAMA, Ken OKAZAKI
Article type: Article
Pages
75-76
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Vascular smooth muscle cells (VSMCs), embedded in arterial media, are normally shielded from direct shear force of flowing blood and are exposed to blood flow after the vascular injury. Because of the importance of intercellular Ca^<2+> in regulating vascular tone and functions, we investigated the effect of fluid flow shear stress on the concentration of intercellular Ca^<2+> of human aortic smooth muscle cells (HASMCs). To address the effect of fluid flow shear stress on intercellular Ca^<2+> concentration, confluent HASMCs were grown on Petri dishes, loaded with aequorin, a Ca^<2+>-activated photoprotein, and the dish was placed in a homemade luminometer chamber after a physiological level of shear stress was imposed on the surface of HASMCs. The luminometer chamber housed inside a highly sensitive photomultiplier tube (PMT) and detected light emission in response to intercellular Ca^<2+> concentration transient. In the presence of 2.0mM extracellular Ca^<2+> shear stress of 16ynes/(cm)^2 induction for 1 minute on the surface of HASMCs elicited a sharp increase followed by plateau elevation of lesser magnitude in the concentration of intercellular Ca^<2+>. Addition of thapsigargin (50nM), an intercellular Ca^<2+>-store blocker, also elicited a peak increase in the Ca^<2+> concentration. Taken together, results suggest that influx of Ca^<2+> through ion channels contributes to the rise in cytosolic Ca^<2+> concentration in response to fluid flow shear stress.
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Masanori Nakamura, Shigeo Wada, Taisei Mikami, Takami Yamaguchi
Article type: Article
Pages
77-78
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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CFD of intraventricular diastolic flow was carried out to study the effects of the shape of the mitral valve orifice during its opening. The results showed that intraventricular blood flow, especially a shape of vortex ring, was changed when different opening mode of the mitral valve orifice was used. A change in blood flow was reflected in a shape of the aliasing area appearing in Color M-mode Doppler (CMD) echocardiograms. Based on the results, we discussed the applicability of CMD echocardiography for detecting mitral valve disorders that involves a change in the shape of the mitral valve orifice. From discussions on fluidic advantages of the formation of intraventricular diastolic vortex, it is suggested that a shape of the valve orifice should be optimized when designing artificial heart valves.
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T. Yamane, T. Kato, O. Maruyama, M. Nishida, T. Okubo, T. Sano, Y. Miy ...
Article type: Article
Pages
79-80
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A hydrodynamic levitation centrifugal pump is being developed for a long-term implantable artificial heart. The hemocompatibility was investigated with numerical analysis and has been verified with animal blood tests. The hemolytic property was improved by expanding the bearing gap and by adjusting the pressure balance and the antithrombogenicity has been improved by adding deep grooves to the hydrodynamic bearings to increase the flow rate through the bearings.
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Aiko WATANABE, Masaaki TAMAGAWA
Article type: Article
Pages
81-82
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes a computational prediction method for hemolysis and thrombus properties in orifice-pipe blood flows. In this study, several types of orifice-pipe flows by using two turbulence models are computed, to which k-ε model with partly patched Launder-Kato model (LK-Zonal model) to improve computational accuracy. Using these database, quantity of hemolysis and thrombus is predicted by estimating (1) turbulent shear stress and (2) transport of concentration of blood coagulation factor. It is concluded that there were possibilities to predict thrombus in the orifice pipe flow, using concentration of blood coagulation factor.
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Sumiaki MATSUO, Masaaki TAMAGAWA, Takayuki NISHIKAWA
Article type: Article
Pages
83-84
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Lattice-Boltzmann Method (LBM) is applied to two-dimension laminar flow over backward-facing step to emulate the accuracy of LBM. The result shows that the accuracy of LBM is almost the same order with that of FDM. The behavior of the initial thrombus is analyzed using flow field from LBM. The possibility of thrombus prediction is expected by adding the influence of two phase flow.
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Shinichi KAWASHIMA, Masaaki TAMAGAWA
Article type: Article
Pages
85-86
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes the developments of microcapsules for Drug Delivery Systems (DDS) by using shock waves. The microcapsules are produced by dropping micro-droplets of Sodium Alginate with Polyvinyl Alcohol into Calcium Chloride. The concentration of Polyvinyl Alcohol is controlled to investigate the material and mechanical properties of produced microcapsule. A small quantity Liquid is injected into the produced micro-capsules for the measurements of the elasticity. Sodium Alginate hardens the micro-capsules, and Polyvinyl Alcohol softens them.
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Masaki KAMACHI, Masaaki TAMAGAWA, Ichiro YAMANOI
Article type: Article
Pages
87-88
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes the fundamental investigations for development of the microcapsules in Drug Delivery Systems (DDS) by Shock Waves. The purpose of this research is to generate a strong shock wave, which can disintegrate the microcapsule can be efficiently, using an optical fiber and a piezo-electric element. It is found that the configuration of fiber end influences the shock wave propagation from the computational result.
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Koji MIYAZAKI, Takeshi IIDA, Hiroshi HORIO, Hiroshi TSUKAMOTO
Article type: Article
Pages
89-90
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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An experimental study on droplet generation for the rapid detection of cells by using cell sorters was conducted. Cell sorters create micro-droplets by controlling waves at surface of a micro-jet which consists of samples and sheath fluid. In this paper the optimum wave number was observed by microscope The ratio of sample flow rates to sheath flow rates and frequency of the wave are also controlled in order to investigate those effects on droplet generation. In addition to the experimental studies linear instability analysis for droplet generation was carried out to obtain optimum parameters to maximize the rate of droplet generation. Analytical solutions agree well with the experimental results of droplet generation.
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Satoru DEGUCHI, Shinichiroh YAMAMOTO, Takashi KOMEDA, Tasuku MIYOSHI, ...
Article type: Article
Pages
91-92
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The purpose of this study was to develop the robotic gait orthosis using two-joint-muscle model. The concept of two joint muscles applied to this orthosis is similar to actual human skeletal muscle system. The air actuator that is high safety was utilized for each joint movement. Six and/or eight rubber tube actuators were used to exert each joint torque of gait orthosis like the actual human muscle. The property of this rubber tube actuator is lightweight and high output power as compared to other electric motor actuator. Therefore, this actuator is easy to attach the frame of gait orthosis, and to control the joint stiffness. It is effective to maintain a static posture against some external forces.
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Toshiya IGATA, Toshiro NORITSUGU, Masahiro TAKAIWA, Daisuke SASAKI
Article type: Article
Pages
93-94
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this study, we have developed a mat which has a function to prevent bedsore. In order to distribute the pressure applied to the body, we have proposed a body pressure distribution strategy by using 24 mats driven independently. And the effectiveness of the proposed method is confirmed through some experiments. In this paper, first of all, the structure of the Medical Care Mat is shown, Afterwards, the effectiveness of the propose method is confirmed through experiment.
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