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Last Updated :2024/07/25
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Name (Japanese)
NishimuraName (Kana)
IkuyaName
201301099848610485
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- 人工関節 潤滑 表面パターン 反応性スパッタ蒸着 開発機械弁 流れの可視化 血液ポンプ 潤滑液の供給 弁機能特性 ジュラルミン 数値流体解析 ル-トプレ-ニング 磁気シール パターン模様 真球度 加速耐久試験機 スメラ層 カップの摩耗 アルミナスパッタ蒸着 動圧軸受 歯根面粗さ 人工心臓 プラ-ク 心臓代用弁 磁性流体シール 摩擦・摩耗現象 溶血量 機能性表面構造 α角 刃先角
Research Areas
Research Experience
Published Papers
- Yoshinori Mitamura, Ikuya Nishimura, Tetsuya YanoJournal of Magnetism and Magnetic Materials 548 168977 - 168977 0304-8853 2022/04
- Ayumi Mitoh, Yuto Suebe, Tadashi Kashima, Etaro Koyabu, Eiji Sobu, Eiji Okamoto, Yoshinori Mitamura, Ikuya NishimuraBio-Medical Materials and Engineering 31 (3) 169 - 178 0959-2989 2020/07/09
- 池田 季生, 見藤 歩, 小薮 栄太郎, 蘇武 栄治, 西村 生哉, 三田村 好矩, 岡本 英治精密工学会学術講演会講演論文集 公益社団法人 精密工学会 2016 883 - 884 2016心臓移植のドナー不足が深刻化する中，解決策として期待され，研究されているものの一つに人工心臓があるが，長期の使用には様々な問題がある．その中でも流体工学的観点から解決可能である問題として血栓症が存在する．本研究では人工心臓血液室の内部の流れを，高速度カメラを用いたPIV法により可視化し，動画データの流動解析，及び流速データからせん断速度を求め，人工心臓内の血栓形成リスクの評価を行った．
- Masaru Higa, Hiromasa Tanino, Ikuya Nishimura, Yoshinori Mitamura, Takeo Matsuno, Hiroshi ItoJOURNAL OF ARTIFICIAL ORGANS 18 (1) 79 - 85 1434-7229 2015/03 [Refereed][Not invited]
This study proposes novel optimized stem geometry with low stress values in the cement using a finite element (FE) analysis combined with an optimization procedure and experimental measurements of cement stress in vitro. We first optimized an existing stem geometry using a three-dimensional FE analysis combined with a shape optimization technique. One of the most important factors in the cemented stem design is to reduce stress in the cement. Hence, in the optimization study, we minimized the largest tensile principal stress in the cement mantle under a physiological loading condition by changing the stem geometry. As the next step, the optimized stem and the existing stem were manufactured to validate the usefulness of the numerical models and the results of the optimization in vitro. In the experimental study, strain gauges were embedded in the cement mantle to measure the strain in the cement mantle adjacent to the stems. The overall trend of the experimental study was in good agreement with the results of the numerical study, and we were able to reduce the largest stress by more than 50 % in both shape optimization and strain gauge measurements. Thus, we could validate the usefulness of the numerical models and the results of the optimization using the experimental models. The optimization employed in this study is a useful approach for developing new stem designs. - MITOH Ayumi, KOYABU Eitarou, SOBU Eiji, KASHIMA Tadashi, IKEDA Sinichi, Nishimura Ikuya, MITAMURA Yoshinori, OKAMOTO EijiThe Proceedings of Mechanical Engineering Congress, Japan 一般社団法人 日本機械学会 2015 (0) _G0200101 - -_G0200101- 2015 [Not refereed][Not invited]
CFD is an important tool to shed light on cerebral aneurysm. Vascular wall shear stress play an important role in the initiated and developed cerebral aneurysm. In this study, fluid dynamics were analyzed throughout cerebral artery using 3D-CAD technology and CFD software. High wall shear stress was occurred in the area connected communicating artery to cerebral artery. This area was in accordance with clinical information. - Ikuya Nishimura, S. Ichikawa, M. Mikami, H. Ishitoya, T. Motomura, M. Kawamura, J. Linneweber, J. Glueck, T. Shinohara, Y. NoseBIO-MEDICAL MATERIALS AND ENGINEERING 23 (1-2) 49 - 55 0959-2989 2013 [Refereed][Not invited]
The Gyro centrifugal pump developed as a totally implantable artificial heart was designed with a free impeller, in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet) in order to prevent thrombus formation and/or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proved by observation of the impeller behavior using a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and rotational speed of the impeller. In order to keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving condition of right and left pump, the magnet-magnet coupling distance was altered by a spacer which was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist), by just changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller rev. It is called "the dynamic RPM suspension". - Toshimasa Ishida, Ikuya Nishimura, Hiromasa Tanino, Masaru Higa, Hiroshi Ito, Yoshinori MitamuraARTIFICIAL ORGANS 35 (4) 404 - 410 0160-564X 2011/04 [Refereed][Not invited]
There are many designs of the femoral stem of a cemented total hip arthroplasty, and mechanical failure of the stem is caused by several factors related to the cement, such as failure of the cement. Optimization of the shape of the stem, especially multiobjective optimization, is required to solve these design problems because a cement fracture is caused by multiple factors. The objective of this study was to determine a stem geometry considering multiple factors at the same time. A three-dimensional finite element model of the proximal femur was developed from a composite femur. A total of four objective functions-two objective functions, the largest maximum principal stress of proximal and distal sections in the cement mantle, for each of the two boundary conditions, walking and stair climbing-were used. The neighborhood cultivation genetic algorithm was introduced to minimize these objective functions. The results showed that the geometry that leads to a decrease in the proximal cement stress and the geometry that leads to a decrease in the distal cement stress were not the same. However, the results of the walking and the stair climbing conditions matched. Five dominant stem designs were considered to be the Pareto solution, and one design was identified as the "better design" for all objective functions. It was shown that multiobjective optimization using a genetic algorithm may be used for optimizing the shape of the femoral stem in order to avoid cement fracture. - Yoshinori Mitamura, Sayaka Takahashi, Shuichi Amari, Eiji Okamoto, Shun Murabayashi, Ikuya NishimuraJOURNAL OF ARTIFICIAL ORGANS 14 (1) 23 - 30 1434-7229 2011/03 [Refereed][Not invited]
A magnetic fluid (MF) seal enables mechanical contact-free rotation of the shaft and hence has excellent durability. The performance of an MF seal, however, has been reported to decrease in liquids. We developed an MF seal that has a "shield" mechanism, and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. Three types of MF seals were used. Seal A was a conventional seal without a shield. Seal B had the same structure as that of Seal A, but the seal was installed at 1 mm below liquid level. Seal C was a seal with a shield and the MF was set at 1 mm below liquid level. Seal A failed after 6 and 11 days. Seal B showed better results (20 and 73 days). Seal C showed long-term durability (217 and 275 days). The reason for different results in different seal structures was considered to be different flow conditions near the magnetic fluid. Fluid dynamics near the MF in the pump were analyzed using computational fluid dynamics (CFD) software. We have developed an MF seal with a shield that works in liquid for > 275 days. The MF seal is promising as a shaft seal for rotary blood pumps. - Yoshinori Mitamura, Sayaka Takahashi, Shuichi Amari, Eiji Okamoto, Shun Murabayashi, Ikuya Nishimura12TH INTERNATIONAL CONFERENCE ON MAGNETIC FLUIDS ICMF12 9 229 - 233 1875-3892 2010 [Refereed][Not invited]
A magnetic fluid (MF) seal enables mechanical contact-free rotation of the shaft and hence has excellent durability. The mechanism and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. The seal was perfect against a pressure of 150 mmHg in a continuous flow of 4.0 L/min for 275 days and against a pressure of 175 mmHg in a continuous flow of 3.9 L/min for 217 days. We have developed a MF seal that works in liquid against pressure mostly used clinically. The magnetic fluid seal is promising as a shaft seal for rotary blood pumps. (C) 2010 Published by Elsevier Ltd - Yoshinori Mitamura, Sayaka Takahashi, Kentaro Kano, Eiji Okamoto, Shun Murabayashi, Ikuya Nishimura, Taka-aki HiguchiARTIFICIAL ORGANS 33 (9) 770 - 773 0160-564X 2009/09 [Refereed][Not invited]
A magnetic fluid (MF) for a rotary blood pump seal enables mechanical contact-free rotation of the shaft and, hence, has excellent durability. The performance of a MF seal, however, has been reported to decrease in liquids. We have developed a MF seal that has a "shield" mechanism and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. Under the condition of continuous flow, the MF seal remained in perfect condition against a pressure of 298 mm Hg (pump flow rate: 3.96 L/min). The seal was also perfect against a pressure of 170 mm Hg in a continuous flow of 3.9 L/min for 275 days. We have developed a MF seal that works in liquid against clinically used pressures. The MF seal is promising as a shaft seal for rotary blood pumps. - KANO Kentaro, TAKAHASHI Sayaka, AMARI Syuichi, NISHIMURA Ikuya, MURABAYASHI Shun, OKAMOTO Eiji, MITAMURA Yoshinori電気学会研究会資料. LD, リニアドライブ研究会 2008 (66) 25 - 30 2008/11/21 [Not refereed][Not invited]
- Leona Abe, Ikuya Nishimura, Yasuharu IzumisawaJOURNAL OF VETERINARY MEDICAL SCIENCE 社団法人日本獣医学会 70 (11) 1191 - 1198 0916-7250 2008/11 [Not refereed][Not invited]
Orthopedic fixation of irreversibly damaged joints entails the use of artificial joints. Porous coated prostheses require no bone cement, but coating to the implant is susceptible to avulsion from the surface. The purpose of this pilot study was to test an improved non-coated grit blast titanium implant having a direct surface roughness of 33.4 mu m with a wide contrast of 251.6 urn between the valleys and peaks, i.e., about ten times rougher than conventional grit blast, and designed with bumpy, acutely articulated depressions. Fifty-six implants (28 grit blast, 28 smooth) were tested in the femora of 7 healthy beagles. Four roughened grit-blast implants were implanted in the left femur and four smooth implants (controls) in the right femur. The 33.4-mu m grit-blasted roughening dramatically enhanced the histological effectiveness, and the mechanical effectiveness improved as a consequence. Bone-to-implant ongrowth attained high apposition and integrity at weeks 12 (76.38%) and 16 (80.35%). Shear strength increased with time and continued to be acceptable (14.5 MPa) at the end Of the Study. Bone matrix was particularly abundant and thick at the end of week 16, indicating progressive mineralization and maturation of remodeled bone matrix and compatibility of the roughened implant. In conclusion, the new grit blast device shows promise as a potentially useful prosthetic implant. Grit blast roughening would facilitate use of the bare implant without coatings or cement, would likely minimize the cost of joint fixation, and would allow relatively easy implantation. - Shape Optimization of THA Hip Stem using Genetic Algorithm(
Symposium on Biomedical Engineering 2007) ISHIDA Toshimasa, NISHIMURA Ikuya, MITAMURA Yoshinori, TANINO Hiromasa, ITO Hiroshi, MATSUNO TakeoTransactions of the Japanese Society for Medical and Biological Engineering : BME 社団法人日本生体医工学会 46 (2) 226 - 231 1347-443X 2008/04/10 [Not refereed][Not invited]
Mechanical failure of the cemented hip stem is mainly caused by several cement mantle problems such as cement fracture. Geometries of the cement mantle and the stem are important factors of failure risks. Shape optimization, especially multi-objective optimization, is required to solve these design problems, because the cement fracture is caused by multiple factors. In this study the stem design was optimized using a genetic algorithm suitable for multi-objective optimization. A three-dimensional finite element model of the proximal femur was developed. Two objective functions, the largest ... - Yosuke Kozaki, Ikuya Nishimura, Yoshinori Mitamura, Shun Murabayashi, Yasuharu Izumisawa, Kouichi KuramotoWORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING 2006, VOL 14, PTS 1-6 14 3251 - + 1680-0737 2007 [Refereed][Not invited]
As a method of porous coating for cementless implant, sintering and diffusion bonding are usually used. But the bonding techniques have trouble with decreasing fatigue strength and boundary separation. In this study, we applied grit blasting for porous coating. Polygonal iron particle was sprayed on the titanium base material by compressed-air power. Porous-processed or raw rods were inserted into femur of dogs, and removed after 4-16 weeks after implantation for evaluation of bonding strength. In all implantation periods, porous-coated rods using grit blasting indicate relatively high bonding strength than untreated. It is assured that the grit blasting can increase the bonding strength between stem and the surrounding bone. - Mechanically Non-contact Axial Flow Blood PumpY.MITAMURA, K.KIDO, T.YANO, D.SAKOTA, R.YOZU, E.OKAMOTO, S.MURABAYASHI, I.NISHIMURABiocybernetics and Biomedical Engineering 27 139 - 146 2007 [Refereed][Not invited]
- NISHIMURA Ikuya, ISHIDA Toshimasa, MURABAYASHI Shun, MITAMURA Yoshinori, NAKAMURA Toshiki, ITO Hiroshi, MATSUNO Takeo, HIGA Masaru, HASEI Minoru, KURAMOTO KouichiTransactions of Japanese Society for Medical and Biological Engineering 社団法人日本生体医工学会 44 (1) 77 - 84 1347-443X 2006/03/10 [Not refereed][Not invited]
As the result of developments in computer technology in recent years, the calculation, simulation and analysis of the stress environment for the artificial hip prosthesis and the femur have been made possible. In order to perform an exact calculation, three-dimensional modeling with the hip prosthesis and femur is required. The modeling of a femur is done by reconstructing the femoral outline data from CT images using three-dimensional CAD. The outline extraction work is performed by the experience and subjectivity of the operator, and the reliability of the data and working efficiency is low. In this paper, algorithms that extract the femur outline from CT images automatically are proposed. A Snake-based outline extraction algorithm is used. Although this method is capable of extracting the cortical bone outline of femoral diaphysis with sufficient accuracy, there was high incorrect detection at the trochanter. The shape of the trochanter is complicated, and it is difficult to process using a simple algorithm. Therefore, we proposed a method of visually expressing the possibility that a certain pixel in an image is high or low. This method is capable of detecting portions of images with high differentiations in value (contrast changes rapidly). It can also detect outlines at the diaphysis and trochanter. The problems of this technique are that the pixels judged as possibly being a part of the outline appear in the portion that is not a true outline, and that the pixels judged as possibly being on the outline may not be continuous. When each method was used independently, neither was capable of performing a positive outline extraction. However, an outline sampling sufficiently high certainty was achieved when using the two methods simultaneously. - H. Tanino, H. Ito, M. Higa, N. Omizu, I. Nishimura, K. Matsuda, Y. Mitamura, T. MatsunoJOURNAL OF BIOMECHANICS 39 (10) 1948 - 1953 0021-9290 2006 [Refereed][Not invited]
The number of stem designs for total hip arthroplasty is increasing, and occasionally design changes have yielded unexpected clinical results. At present, we are not able to clearly identify which parameter of the stem is most important, and the optimum value of many parameters. The goals of this study were to identify which parameter is most important, to understand the effect of design change, and to find the optimum stem shape. For this purpose, we used adaptive p-method together with three-dimensional computer-aided design software program for the design sensitivity analysis (DSA) and shape optimization of the stem. The results suggested that increasing the lateral and medial width of the distal cross-section together with decreasing the medial-lateral width and the medial radius of the distal cross-section from the default value would lead to a decrease in the largest maximum principal stress of the distal cement. The medial width of middle cross-section, however, was not so simple. The result of DSA suggested that decreasing this parameter from the default value decreased the stress in the distal cement, but the optimum shape was obtained by increasing this parameter. The method used in this study will assist our engineers and surgeons in the process of modifying and optimizing the stem design. (c) 2005 Elsevier Ltd. All rights reserved. - ISHIDA Toshimasa, YAGIHASHI Kouta, NISHIMURA Ikuya, TANINO Hiromasa, ITO Hiroshi, MATSUNO Takeo, MITAMURA Yoshinori, HARMAN M. K, BANKS S. A, MODGE W. A日本臨床バイオメカニクス学会誌 = Proceedings of ... Annual Meeting of Japanese Society for Clinical Biomechanics and Related Research 26 (0) 233 - 237 1340-9018 2005/10/01 [Not refereed][Not invited]
- YANO Tetsuya, MITOH Ayumi, MITAMURA Yoshinori, NISHIMURA Ikuya, MURABAYASHI Shun, YOZU RyoheiTransactions of the Japanese Society for Medical and Biological Engineering : BME 社団法人日本生体医工学会 43 (1) 85 - 92 1347-443X 2005/03/10 [Not refereed][Not invited]
Hemolysis is a major factor for developing successful blood pumps. A major cause of hemolysis is the mechanical stress acting on the corpuscles passing through the pump. The empirical formula, which expresses the relationship of the shear stress, exposure time, and hemoglobin release serves as a basic model for the estimation of blood damage. We have conducted computational fluid dynamics (CFD) -based assessment for the hemolysis within the blood pump using one of the above mathematical models. Assuming that the red blood cells pass along the streamlines, a blood damage index was calculated... - TANINO Yukinori, HIGA Masaru, NISHIMURA Ikuya, ISHIDA Toshimasa, OHATA Noboru, MITAMURA Yoshinori日本臨床バイオメカニクス学会誌 = Proceedings of ... Annual Meeting of Japanese Society for Clinical Biomechanics and Related Research 25 (0) 223 - 228 1340-9018 2004/11/01 [Not refereed][Not invited]
- 西村 生哉, 清水 亮太, 中村 聡喜, 松野 丈夫, 三田村 好矩年次大会講演論文集 : JSME annual meeting 一般社団法人日本機械学会 2004 (5) 129 - 130 2004/09/04 [Not refereed][Not invited]
A high prevalence of thigh pain has been reported after cementless total hip arthroplasty (cementless THA). But it is still unknown about the in-depth mechanism. Therefore in order to investigate the relevance between the occurrence of thigh pain and the stress in femur after cementless THA, the experiments on animals were carried put. The animalexperiments revealed that reaming volume of the medullary cavity have an effect on the occurrence of thigh pain. - YAGIHASHI Kouta, MITAMURA Yoshinori, NISHIMURA Ikuya, ISHIDA Toshimasa, ITO Hiroshi, TANINO Hiromasa, NAKAMURA Toshiki, MATSUNO TakeoIEICE technical report. ME and bio cybernetics 一般社団法人電子情報通信学会 104 (129) 21 - 23 0913-5685 2004/06/11 [Not refereed][Not invited]
Prosthetic impingement after THA is to different for the angle and shape of the implant. Purpose of this study is examine the range of motion(ROM) on a computer when angle and shape of the implant are changed. The angle was measured in the flexion, extension, adduction direction by every 0.1 degrees. All 324 patterns of the above model were measured. As a result hen the radius of neck and the neck shaft angle decrease, the increase of the ROM expected. - T Seno, Y Izumisawa, Nishimura, I, S Maehara, T Kushiro, MA Umar, S Wakaiki, K Yamashita, T KotaniJOURNAL OF VETERINARY MEDICAL SCIENCE 社団法人日本獣医学会 66 (3) 315 - 318 0916-7250 2004/03 [Not refereed][Not invited]
Screw and laser (SL) column by making screw threads and forming small holes using laser irradiation on the base metal and conventional beads coating (BC) columns were embedded into the shaft of canine femurs, and compared the implant fixation to the host bone. The interfacial strength in SL columns was almost equivalent as BC columns, and bone-column contact rate was higher than BC columns significantly at twelve weeks after implantation. The newly devised SL surface had almost equivalent bone fixation strength comparable to the conventional BC surface. Also, this surface should provide a useful porous surface for use in artificial joints since there is no risk of surface structure detachment. - Nishimura, I, S Ichikawa, M Mikami, H Ishitoya, T Motomura, A Kawamura, J Linneweber, J Glueck, T Shinohara, Y Nose, Nishimura, IASAIO JOURNAL 49 (6) 744 - 747 1058-2916 2003/11 [Refereed][Not invited]
The Gyro centrifugal pump, developed as a totally implantable artificial heart, was designed with a free impeller in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet balance) to prevent thrombus formation or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller is lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proven by observation of the impeller behavior by means of a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and the rotational speed of the impeller. To keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving conditions of right and left pumps, the magnet-magnet coupling distance was altered by a spacer that was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist) by changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller revolution. This is called "the dynamic revolutions per minute suspension." - K Sekine, Y Mitamura, S Murabayashi, Nishimura, I, R Yozu, DW KimARTIFICIAL ORGANS 27 (10) 892 - 896 0160-564X 2003/10 [Refereed][Not invited]
A rotating impeller in a rotary blood pump requires a supporting system in blood, such as a pivot bearing or magnetic suspension. To solve potential problems such as abrasive wear and complexity of a supporting system, a magnetic fluid seal was developed for use in an axial-flow blood pump. Sealing pressures at motor speeds of up to 8,000 rpm were measured with the seal immersed in water or bovine blood. The sealing pressure was about 200 mm Hg in water and blood. The calculated theoretical sealing pressure was about 230 mm Hg. The seal remained perfect for 743 days in a static condition and for 180+ days (ongoing test) at a motor speed of 7,000 rpm. Results of measurement of cell growth activity indicated that the magnetic fluid has no negative cytological effects. The specially designed magnetic fluid shaft seal is useful for an axial-flow blood pump. - HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, ITOH Hiroshi, MATSUNO Takeo, MITAMURA YoshinoriTRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A 一般社団法人日本機械学会 69 (679) 689 - 694 0387-5008 2003/03/25 [Not refereed][Not invited]
When cemented hip replacement implants are developed using a finite element method (FEM), the validation of the inplants comparing with experimental tests and clinical survival data should be required. As the first step, the optimum shape of the femoral component of total hip arthroplasty (THA) was designed to minimize the stress peak in the cement mantle that is the primal cause for fixation failure. In the next step, the strain in the cement mantle surrounding the cemented femoral components of THA was measured using strain gauges embedded within the cement mantle adjacent to the developed femoral stem to validate the optimization results of FEM. As a result of this study, optimum shape of femoral component was developed and the FEM results were validated by strain gauge experiments. - T Seno, Y Izumisawa, Nishimura, I, S Maehara, T Yokoyama, K Yamashita, T KotaniJOURNAL OF VETERINARY MEDICAL SCIENCE 社団法人日本獣医学会 65 (3) 419 - 422 0916-7250 2003/03 [Not refereed][Not invited]
Titanium columns (Ti-6A1-4V) were treated with arc-deposition to roughen the surface enough to anchor-the bone, and then coated with hydroxyapatite (HA) at a thickness of 5 mum by the sputtering technique. Columns were implanted into dog femurs, and fixation of columns to bone due to bone-ingrowth was assessed histologically and with the push-out test. The HA-coated columns were inserted in the shafts of the right femurs of 2 dogs. As a control, columns that were only arc-deposited (non-coated columns) were inserted into the left femurs. The interfacial strength was higher for the HA-coated columns than for the non-coated columns. Coating a rough surface with an HA layer using a sputtering technique reinforces interfacial strength between bone and implants. - Toshimasa Ishida, Ikuya Nishimura, Masaru Higa, Hiromasa Tanino, Hiroshi Ito, Takeo Mtasuno, Yoshinori MitamuraAmerican Society of Mechanical Engineers, Bioengineering Division (Publication) BED 55 207 - 208 1071-6947 2003 [Refereed][Not invited]
A multiobjective optimization was used to solve several failure problems of cemented total hip arthroplasty. The objective functions were three the principal stress in the bone cement, the shear stress of stem/cement interface and cement/bone interface. In the results, the cement stress was reduced by 49%, the stem-cement stress was reduced by 68%, and the cement-bone stress was reduced by 43%, compared with the basic model. - S Ichikawa, K Nonaka, J Linneweber, S Kawahito, T Motomura, H Ishitoya, M Mikami, Nishimura, I, J Glueck, T Shinohara, Y NoseARTIFICIAL ORGANS 26 (12) 1050 - 1052 0160-564X 2002/12 [Refereed][Not invited]
The Gyro permanently implantable pump consists of a sealless pump housing and an impeller supported with a double pivot bearing. The secondary vanes are attached to increase the secondary flow to avoid thrombus formation behind the impeller. Flow visualization studies using an oil film method were performed on three types of impellers: no secondary vanes, 0.5 mm height secondary vanes, and 1.0 mm height secondary vanes. Comparison studies of these impellers were performed on the surfaces of the impeller bottom and bottom housing. Regarding the surface of the impeller bottom, the impeller with no secondary vanes had the least stagnant areas around the shaft. On the other hand, the impeller having 1.0 mm height secondary vanes had the most distinguished flow lines on the bottom housing. Overall, the impeller secondary vanes with a height of 0.5 mm (current design) seemed to create the most effective secondary flow. - HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, ITOH Hiroshi, ISHIDA Toshimasa, MATSUNO Takeo, MITAMURA Yoshinori日本臨床バイオメカニクス学会誌 = Proceedings of ... Annual Meeting of Japanese Society for Clinical Biomechanics and Related Research 23 (0) 167 - 172 1340-9018 2002/11/01 [Not refereed][Not invited]
- H Ishitoya, M Kawamura, J Linneweber, T Motomura, S Ichikawa, Nishimura, I, J Glueck, T Shinohara, Y NoseARTIFICIAL ORGANS 26 (11) 959 - 963 0160-564X 2002/11 [Refereed][Not invited]
Titanium alloy (Ti) commonly is used for long-term blood pumps as a conventional blood contacting material. Thrombus formation in the pump, however, is still a critical problem. Once thrombin is generated on the Ti surface, it activates platelets and the coagulation cascade, leading to thrombus formation. It would be expected that an inhibition of thrombin generation on a blood-contacting surface would prevent thrombus formation. In this study, the titania gel (Ti-gel) on the surface of Ti was formed with chemical modification. The surface structure and its effects on the coagulation cascade were evaluated. Scanning electron microscopic study revealed numerous cracks on the dried surface of Ti-gel, indicating a water-enriched layer. Blood coagulation on the Ti-gel was less than that on the Ti. Generated thrombin on the Ti-gel was less than that on the Ti in both the extrinsic and intrinsic pathways. There was no statistical difference of thrombin degradation. These results suggest that coagulation cascade on the Ti surface was inhibited by the Ti-gel formation. The Ti-gel may have better antithrombogenic characteristics for blood pumps because of its antiblood-coagulation effects. - Hiroshi Ito, Akio Minami, Takeo Matsuno, Hiromasa Tanino, Toshio Yuhta, Ikuya NishimuraJournal of Arthroplasty 16 (8) 1024 - 1029 0883-5403 2001 [Refereed][Not invited]
This study evaluated the sphericity of bearing surfaces in total hip arthroplasty. The out-of-roundness of metal femoral heads, the inner surface of polyethylene liners, and commercially available ball bearings was measured. The hip prostheses were obtained directly from the manufacturers. The sphericity of the bearing surfaces was significantly inferior to that of the ball bearings. The sphericity of the femoral head on the sagittal plane was inferior to that on the transverse plane. Several significant differences were found among different manufacturers. The sphericity of the femoral head on the sagittal plane and that of polyethylene significantly improved in 1999 and 2000 compared with those in 1995, Further improvement is desirable, however, because good sphericity is expected to prolong the functional performance of the prosthesis after total hip arthroplasty. - Reduction of polyethylene wear by concave dimples on the frictional surface in artificial hip jointsH Ito, K Kaneda, T Yuhta, Nishimura, I, K Yasuda, T MatsunoJOURNAL OF ARTHROPLASTY 15 (3) 332 - 338 0883-5403 2000/04 [Not refereed][Not invited]
For the purpose of reduction of polyethylene wear generated in artificial hip joints, concave dimples were formed on the surface of the metal femoral head by electrical discharge etching with the constant diameter of 0.5 mm. pitch of 1.2 inm, and depth of 0.1 mm. Using a hip joint simulator the total amount of polyetylene wear was 7.2 mg in the concave-patterned condition and 23.1 mg in the nonpatterned condition. The reasons for the reduction of polyethylene wear by the concave pattern may be i) a reduction of abrasive wear by providing escape dimples for wear particles and ii) an improvement in the lubricity on the frictional surface by Lire supply of lubricant that is stored in dimples. - The outline sampling strategies for the femoral CT imagesI. Nishimura, T. Ishida, S. Murabayashi, Y. Mitamura, T. Nakamura, H. Ito, T. Matsuno, M. Higa, M. Hasei, K. KuramotoProceeding of World Congress on Medical Physics and Biomedical Engineering 14 2441 - 2444 [Refereed][Not invited]
MISC
- NISHIMURA Ikuya, MITOH Ayumu, ANAGUCHI Yuko Mechanical Engineering Congress, Japan 2015- "G0200305 -1"-"G0200305-4" 2015/09/13A cause of thigh pain after cementless THA is still uncertain. The final goal of this study is clear up the cause for thigh pain and the development of painless cementless stem. For that, the objective of this paper is to make the animal model of thigh pain and to establish the method of evaluating the pain. We made special pin that pushes from the inside and expands the rat bone. The rat that the pin was implanted was bred with the cage. The loadcells were arranged on four corners of the cage in order to calculate rat's dynamics parameters, namely, rat's position, stay rate, total movement distance, crosspoint and errorpoint. There is the resulting rat grimace scale score (RGS score) as an index that evaluates the pain that the rat feels. RGS score is a method of evaluating the pain from the rat's facial expression. On the other hand, the method of the proposal in this study is a method of evaluating the pain from the activity of the rat. This new index shall be designated as "the resulting rat activity scale score (RAS score)". RAS is more objective and more quantitative.
- Ito Hiroshi, Atsuta Yuji, Tanino Hiromasa, Nishimura Ikuya, Matsuno Takeo 旭川医科大学研究フォーラム 13- (1) 32 -37 2013/02雑誌掲載版Thigh pain often appears after total hip arthroplasty (THA) using a cementless femoral component. It is known that sensory nerve endings exist in the medullary cavity of the bone. The purpose of this study was to investigate, in a rabbit model, whether the pressure on the femoral bone applied from inside the medullary cavity of the femoral bone causes flexion withdrawal reflex. We loaded pressure on the inside of the medullary cavity of the femoral bone and observed whether muscle activity occurs. The pain resulting from pressure was evaluated by hind limb flexor activity produced by the flexor reflex. An integrated waveform was used to evaluate the degree of muscle activity. For the laboratory-animal models, we prepared the medullary cavity of the rabbits in two ways. In the rabbits with slight reaming, the flexor reflex appeared in low pressure. However, in rabbits with greater reaming, the flexor reflex did not appear, even under high pressure. This suggests that the pain was induced when the sensory nerve endings remained in the inside of the medullary cavity of the femoral bone and the sensory nerve endings were stimulated by the stress.
- 伊藤 浩, 松野 丈夫, 谷野 弘昌, 山中 康裕, 佐藤 達也, 大水 信幸, 中村 聡喜, 三浪 明男, 西村 生哉, 比嘉 昌 北海道整形災害外科学会雑誌 50- (2) 190 -194 2009/03 [Not refereed][Not invited]
著者版日本人の脱臼性および亜脱性股関節症患者73関節に対して大腿骨全長5mm間隔でCT撮影を施行し、パーソナルコン ピューター上にて皮質骨の外形、内形の輪郭を抽出した。3次元CADであるPro ENGINEER(Parametric Technology)にて大腿骨の各種計測を行った。症例の中には大腿骨頸部前捻が強く、骨髄腔がかなり狭い例が含まれており、ステムを細くストレート にし、オフセットを確保した製品が必要であることが明らかになった。3次元有限要素法によりデザインの妥当性を検討し、ステムサイズ(1〜7号)を決定し た。この製品はハイブリッド型THA4-U Hip Systemとして、ナカシマメディカルより販売されている。当科および関連病院にて、約550関節の初回THA手術が終了しているが、ほぼテンプレート を用いた術前計画通り手術が行われ、短期成績は良好である。 - Ishida Toshimasa, Nishimura Ikuya, Tanino Hiromasa, Ito Hiroshi, Matsuno Takeo, Mitamura Yoshinori The proceedings of the JSME annual meeting 2005- (5) 207 -208 2005/09/18 [Not refereed][Not invited]
Total hip arthroplasty (THA) is mainly used for the patients, who are affected with rheumatoid arthritis, coxarthrosis, and so on. The long-term success of total hip arthroplasty depends on the chance of acrylic cement failure and interface disruption. The purpose of this study is to minimize the risks of cement failure by using optimization. A generic three-dimensional FEM model of the proximal femur containing a cemented femoral stem of a total hip arthroplasty was developed. The design parameters are defined on cross section of stem. The design objective was to minimize several principal... - Higa Masaru, Nishimura Ikuya, Maeda Fuyuhiko, Seno Takahiro, Izumisawa Yasuharu, Mitakura Yoshinori The proceedings of the JSME annual meeting 2004- (5) 127 -128 2004/09/04 [Not refereed][Not invited]
Canine total hip replacement (THA) is one of the treatments of canine osteoarthritis (OA). The bone screws are used to fix acetabular cup on THA. Two screws are mainly used. However, compared to human THA, these screws were not considered enough about direction, size, and so on. The porpose of this study is to consider the possibility of three screws fixing. Finite element method was used for comparing two screws fixing and three screws. Rightly, three screws have higher fixing strength. However, these also have higher risk of bone fracture. From results, three screws and two screws are not... - YANO Tetsuya, Mitoh Ayumi, SEKINE Kazumitsu, MITAMURA Yoshinori, NISHIMURA Ikuya, MURABAYASHI Shun, YOZU Ryohei The proceedings of the JSME annual meeting 2004- (5) 189 -190 2004/09/04 [Not refereed][Not invited]
The successful use of a continuous flow blood pump depends on the degree of blood trauma. A major cause of blood trauma is the mechanical stress acting on the corpuscles passing through the pump, hi this study, assuming that the red blood cells passed along the streamlines, a blood damage index was calculated based on the changes in shear stress with time along streamlines starting from entrance plane of the pump. Indices of hemolysis should be estimated by analysis under the same operating conditions (i.e. flow rate and pressure head) to compare the hemolysis levels of different pumps The ... - 石田 敏真, 西村 生哉, 比嘉 昌, 谷野 弘昌, 伊藤 浩, 松野 丈夫, 三田村 好矩 生体医工学 : 日本エム・イー学会誌 42- (2) 135 -135 2004/06/10 [Not refereed][Not invited]
- Sekine Kazumitsu, Mitamura Yoshinori, Murabayashi Shun, Nishimura Ikuya, Yozu Ryohei The proceedings of the JSME annual meeting 2003- (5) 95 -96 2003/08/05 [Not refereed][Not invited]
A magnetic fluid (MF) seal was specially designed for use in an axial-flow blood pump. There are some potential problems to be solved for the use as a shaft seal for blood pumps. Experimental and theoretical sealing pressures, a long-term performance of the MF seal and biocompatibility of MF were studied. The sealing pressure was about 200mmHg in blood in the experiments. The theoretical sealing pressure was over 300mmHg with the use of high magnetization MF. The results of long-term performance tests showed that the durability of the seal was over 1 year. The results of cytotoxicity tests ... - SHIMIZU Ryota, NISHIMURA Ikuya, NAKAMURA Toshiki, MATSUNO Takeo, MITAMURA Yoshinori The proceedings of the JSME annual meeting 2003- (7) 141 -142 2003/08/05 [Not refereed][Not invited]
A high prevalence of thigh pain has been reported after cementless total hip arthroplasty. But it is still unknown about the in-depth mechanism. To study the relevance between the occurrence of thigh pain and the stress in femur, we made animal experiment and actually put pressure on rabbit thigh from the medullary cavity using balloon catheter. The results of the experiments are reported here. - 今野 慎介, 村林 俊, 西村 生哉, 片山 茂, 三田村 好矩, 米川 元樹, 岡本 英治 生体医工学 : 日本エム・イー学会誌 41- (1) 63 -63 2003/03/10 [Not refereed][Not invited]
- Ishida Toshimasa, Nishimura Ikuya, Higa Masaru, Mitamura Yoshinori バイオエンジニアリング講演会講演論文集 2003- (15) 409 -410 2003/01/20 [Not refereed][Not invited]
- YANO T, SEKINE K, MITOH A, MITAMURA Y, OKAMOTO E, KIM Dw, NISHIMURA I, MURABAYASHI S, YOZU R Artificial Organs 27- (10) 920 -925 2003 [Not refereed][Not invited]
- Ishida Toshimasa, Nishimura Ikuya, Higa Masaru, Mitamura Yoshinori The proceedings of the JSME annual meeting 2002- (6) 53 -54 2002/09/20 [Not refereed][Not invited]
The long-term success of total hip arthroplasty (THA) depends on the chance of acrylic cement failure and interface disruption. This chance can be diminished by an optimal long-transfer mechanism, whereby stress concentrations are avoided. Implant design is decisive for success or failure. This paper introduces an optimum design of the hip prosthesis. A generic three-dimensional FEM model of the proximal femur containing a cemented femoral stem of a total hip arthroplasty was developed. The design objective was to minimize the largest maximum principal stress in the cement. To verify validi... - HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, ITOH Hiroshi, MATSUNO Takeo, MITAMURA Yoshinori Journal of the Japan Society for Precision Engineering 68- (7) 948 -952 2002/07/05 [Not refereed][Not invited]
The present paper introduces an optimum design of the hip prosthesis and a method for shape optimization which minimizes the stress concentration within the cement mantle. A gradient projection method of numerical optimization and a p-version three-dimensional FEM of stress analysis were employed. A generic three-dimensional FEM model of the proximal femur containing a cemented fomoral stem of a total hip arthroplasty was developed. The three types of analysis was then performed in this study. First, stastic stress analysis measuring the stress in the bone cement was performed. The generic model was then valified parametrically by changing the each parameters individually that compose the stem geometry measureing the stress occuring within the cement mantle concurrently. As it is called design sensitivity analysis was performed. Finally, optimal stem shape was desigend using shape optimization. The design objective was to minimize the largest maximum principal stress in the cement. The results of shape optimization showed considerable reduction in stress concentration within the cement mantle compared to the starting design that were used. Moreover, the optimal stem shape obtained in this study showed unique geometry differ from the standard trend that has been believed to be better. The results of this study has shown to be attractive for evaluating stem design and develop the optimal new stem shape. - SATOH Shunsuke, MITAMURA Yoshinori, HIRAYAMA Yasushi, YUHTA Toshio, NISHIMURA Ikuya IEICE technical report. ME and bio cybernetics 102- (137) 9 -12 2002/06/14 [Not refereed][Not invited]
This study was aimed at developing a method for measuring dental color using a digital image. The teeth of subjects, shade guides, and standard color samples were photographed with a digital camera under different lighting conditions. The RGB values of them were measured from the digital images. The values were changed into the Munsell values and the CIEL^*a^*b^* values. The calculated values were compared with dentist's diagnostic results, and dental chroma meter. Repeatability under the same condition was evaluated. The results indicated that dental color measured by digital images. - 瀬野 貴弘, 泉澤 康晴, 川村 祐介, 西村 生哉, 伊藤 浩, 大水 伸幸, 山下 和人, 小谷 忠生 獣医麻酔外科学雑誌 = Japanese journal of veterinary anesthesia & surgery 33- (0) 150 -150 2002/06/10 [Not refereed][Not invited]
- 西村 生哉, 大水 信幸, 清水 亮太, 三田村 好矩 精密工学会大会学術講演会講演論文集 2002- (1) 646 -646 2002/03/01 [Not refereed][Not invited]
- Matsuda Kazuhiro, Nisimura Ikuya, Tanino Hiromasa, Higa Masaru, Mitamura Yosinori The proceedings of the JSME annual meeting 0- (1) 79 -80 2001/08/22 [Not refereed][Not invited]
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 concentrati... - Matsuno Takeo Asahikawa Medical College research bulletin 2- (1) 30 -35 2001/06/30 [Not refereed][Not invited]
出版社版人工股関節置換術は末期股関節症患者に対して疼痛の軽減や可動域の回復を目的として行われる.以前は術後15年で,その約半数に弛みが生じるとされていたが,工学的技術及び手術手技的技術の改良で現在では術後15年における弛み率は5%以下になっている.しかし依然として人工股関節の経年的弛みは避けることの出来ない合併症であることも事実である.人工股関節弛みの最も大きな要因と考えられているのは関節摺動面において発生するポリエチレン摩耗粉である.将来的にポリエチレン摩耗粉の発生を減少(或いは防止)させることが可能となれば,一生弛むことのない人工股関節も夢ではない - Matuda Kazuhiro, Nisimura Ikuya, Tanino Hiromasa, Higa Masaru, Mitamura Yosinori IEICE technical report. ME and bio cybernetics 101- (130) 9 -14 2001/06/15 [Not refereed][Not invited]
Loosening of cemented femoral hip stems could be initiated by failure of the cement mantle due to high cement stress. This report describes the three dimensional shape optimization of cemented femoral hip stems. Finite elements method (FEM) was combined with an optimization procedure to minimize stresses in the cement mantle adjacent to cemented femoral hip stem. We selected the p methods of analysis. The p-adaptive methods allows for greater shape changes without sacrificing the accuracy of the analysis. The results of the design optimization showed considerable reduction in stress concent... - HIGA Masaru, NISHIMURA Ikuya, MATSUDA Kazuhiro, TANINO Hiromasa, OMIZU Nobuyuki, MITAMURA Yoshinori バイオエンジニアリング講演会講演論文集 2001- (13) 154 -155 2001/01/15 [Not refereed][Not invited]
- NISHIMURA Ikuya, HIGA Masaru, YUHTA Toshio, ITO Hiroshi, TANINO Hiromasa, OOMIZU Nobuyuki, MURABAYASHI Shun, MITAMURA Yoshinori Journal of the Japan Society for Precision Engineering 66- (10) 1594 -1598 2000/10/05 [Not refereed][Not invited]
New surface structure with regular patterning for the frictional surfaces of the artificial joints was designed to improve the wear problems. The lubrication properties for the cup ( ultrahigh molecular weight polyethylene, UHMWPE) vs. ball ( Co-Cr alloy) were studied to evaluate the wear and surface roughness. The surface structure is the dents pattern which has diameter of 0.5mm, pitch of 1.2mm. In this study, such surface patterns were applied to artificial hip joints, and the effects of regular patterning on the frictional surface were investigated by using a joint simulator. The amount of wear of the cup that was in contact with the patterned head was only half that of the cup that was in contact with the non-patterned head, and the surface roughness of the cup with a non-patterned head was three-times greater than that of the cup with a patterned head. These results demonstrates that the lubrication properties can be improved by patterning of the frictional surface of the artificial joint. Consequently, the life of the artificial joint can be extended by the patterning on the frictional surfaces. - 青木 良太, 西村 生哉, 三田村 好矩 精密工学会大会学術講演会講演論文集 2000- (2) 225 -225 2000/09/01 [Not refereed][Not invited]
- ITO H 日本整形外科學會雜誌 74- (8) S1661 2000/08/25 [Not refereed][Not invited]
- HIGA M 日本整形外科學會雜誌 74- (8) S1783 2000/08/25 [Not refereed][Not invited]
- OMIZU N 日本整形外科學會雜誌 74- (8) S1784 2000/08/25 [Not refereed][Not invited]
- HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, MITAMURA Yoshinori The proceedings of the JSME annual meeting 2000- (2) 61 -62 2000/07/31 [Not refereed][Not invited]
Fatigue failure of the acrylic cement and resulting disruption of the bone-cement interface can limit the long-term clinical success of the cemented artificial hip joint. In order to overcome this problem optimal shape design prosthesis is required. This study describe a result of the design shape analysis (DSA) and the numerical shape optimization whereby the finite element method is used to determine optimal shape for the femoral stem of hip prosthesis in order to minimize the maximal value of the 1^<st> principal stress at the cement mantle. - 谷野 弘昌, 伊藤 浩, 大浦 久典, 西村 生哉, 比嘉 昌, 三田村 好矩, 勇田 敏夫, 松野 丈夫 日本整形外科學會雜誌 = The Journal of the Japanese Orthopaedic Association 73- (8) S1699 1999/08/25 [Not refereed][Not invited]
- 伊藤 浩, 金田 清志, 松野 丈夫, 谷野 弘昌, 勇田 敏夫, 西村 生哉 日本整形外科學會雜誌 = The Journal of the Japanese Orthopaedic Association 73- (8) S1818 1999/08/25 [Not refereed][Not invited]
- NISHIMURA Ikuya, YUHTA Toshio, ITOH Hiroshi, HIRAYAMA Mitsuhisa, SHIKATA Jitsuto, TANINO Hiromasa, MATSUNO Takeshi 生体材料 16- (5) 254 -259 1998/10/10 [Not refereed][Not invited]
- 西村 生哉, 四方 實人, 三田村 好矩, 勇田 敏夫, 比嘉 昌 精密工学会大会学術講演会講演論文集 1998- (2) 393 -393 1998/09/01 [Not refereed][Not invited]
- ITO H 日本整形外科學會雜誌 = The Journal of the Japanese Orthopaedic Association 72- (8) S1287 1998/08/25 [Not refereed][Not invited]
- SHIKATA Jitsuto, NISHIMURA Ikuya, SHIMOOKA Toshiyuki, YUHTA Toshio, SHIMIZU Koichi IEICE technical report. ME and bio cybernetics 97- (622) 9 -14 1998/03/20 [Not refereed][Not invited]
One of the reasons of osteolysis has been recognized to be the wear particles of ultra-high molecular weight polyethylene (UHMWPE). We examined the effectiveness of "patterning" and "high sphericity" to prolong the life of an artificial hip joint by preventing the production of the wear debris. The artificial hip joints used in this study were those commercially available for implantation. A pendulum hip joint simulator was developed for friction tests. The load was 200kgf on the friction surface and the range of swing was 60 degrees. The number of swings was one million in the frequency of... - ITO H 日本整形外科學會雜誌 = The Journal of the Japanese Orthopaedic Association 71- (8) 1785 -1785 1997/08/25 [Not refereed][Not invited]
- 李 桓成, 西村 生哉, 下岡 聡行, 勇田 敏夫 精密工学会大会学術講演会講演論文集 1997- (1) 1289 -1290 1997/03/01 [Not refereed][Not invited]
- 李 恒成, 西村 生哉, 下岡 聡行, 勇田 敏夫 精密工学会大会学術講演会講演論文集 1996- (2) 239 -240 1996/09/01 [Not refereed][Not invited]
- 藤丸 真南海, 勇田 敏夫, 西村 生哉 精密工学会大会学術講演会講演論文集 1996- (1) 343 -344 1996/03/01 [Not refereed][Not invited]
- NISHIMURA Ikuya, YUHTA Toshio, ITOH Hiroshi, KISIMOTO Takafumi, GOTOH Ryuuji, MATSUNO Takeo, KANEDA Kiyoshi 生体材料 13- (6) 266 -271 1995/12/01 [Not refereed][Not invited]
- NISHIMURA Ikuya, YUHTA Toshio, MATSUBARA Yoshihiro Journal of the Japan Society of Precision Engineering 61- (4) 576 -580 1995/04/05 [Not refereed][Not invited]
Experimental study was carried out on the properties of hydroxyapatite(HAp) films that was deposited by RF-sputtering on the polymer(silicone rubber, PET). During sputtering, the polymer were cooled by especially manufactured water-cooled unit. Though the adhesion strength between the HAp film and PET is not strong, that between the HAp film and silicone rubber is quite strong nearly equal to the fracture strength of silicone rubber. Although every HAp film has amorphous structure, it is possible to crystallize by soaking the films in the Hanks' solution. These results arc useful to develop... - T YUHTA, Y KIKUTA, Y MITAMURA, K NAKAGANE, S MURABAYASHI, NISHIMURA, I JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 28- (2) 217 -224 1994/02 [Not refereed][Not invited]
The surface modification of metals by the application of blood compatible ceramics is one approach to developing durable and blood-compatible materials. The blood compatibility of sputter-deposited alumina films was investigated in vitro. The alumina films were prepared by reactive sputtering and conventional sputtering. Diffractometer studies of the alumina films indicate that the sputter-deposited alumina films have amorphous structures. Electron spectroscopy chemical analysis studies of the alumina films indicate that the sputter-deposited alumina films are nonstoichiometric (O/Al ratio of 1.15-1.66). We examined the platelet reaction to the alumina films and the intrinsic coagulation factor XII activation by the alumina films. Medical grade segmented polyurethane was also tested. The alumina films experienced an adhesion of about 50% fewer platelets than the segmented polyurethane. Also, fewer platelet morphologic changes were observed on the alumina films than on the segmented polyurethane. Factor XII activation was less on the alumina films than on the segmented polyurethane. Surface modification by the sputter-deposited alumina films is promising for developing blood-compatible and durable materials. (C) 1994 John Wiley and Sons, Inc. - 菊田 幸明, 中兼 雅之, 西村 生哉, 見藤 歩, 村林 俊, 勇田 敏夫 Bulletin of the Faculty of Engineering,Hokkaido University (161) p55 -62 1992/10
- 西村 生哉, 勇田 敏夫, 斉藤 剛 Bulletin of the Faculty of Engineering,Hokkaido University (158) p87 -94 1992/01
- NISHIMURA Ikuya, YUHTA Toshio, SAITOH Tsuyoshi Journal of the Surface Finishing Society of Japan 43- (6) 584 -588 1992 [Not refereed][Not invited]
This paper presents the mechanical characteristics and structures of titanium nitride (TiN) films formed by reactive sputter deposition. TiN films formed at N2 partial pressures below 2.0×10-3Pa are almost pure titanium and have a fibrous structure. It is thought that nitrogen collects in the dislocations. Films formed at N2 partial pressure of 2.0×10-3Pa were hardest and had the lowest coefficients of friction. They had a double structures, with a fine-grain structure above a columnular structure and it is thought that hardness was due to the existence of the fine-grain structure. Films fo...
Books etc
- 改訂 臨床工学技士のための機械工学西村生哉
2022/09 - 臨床工学技士のための生体計測装置学三田村好矩, 西村生哉
2017/07 - 臨床工学技士のための電気工学西村生哉 (Single work)
2014 - 臨床工学技士のための機械工学西村生哉 (Single work)
2013/01 - 臨床工学技士のための生体物性村林 俊 (Supervisor)
2012/06 - 超精密生産技術大系、第4巻 第6編(Joint work第2章 第4節、人工骨)
株式会社フジ・テクノシステム 1996/02
Research Projects
- Japan Society for the Promotion of Science：Grants-in-Aid for Scientific ResearchDate (from‐to) : 2002 -2005Author : MITAMURA Yoshinori, MURABAYASHI Shun, NISHIMURA Ikuya, OKAMOTO Eiji, YOZU Rhohei, YAMBE TomoyukiAn axial flow blood pump was developed using a hydrodynamic pressure bearing, a magnetic fluid seal and a brushless direct current motor. This enabled contact-free rotation of the impeller without material wear. The motor rotor is directly connected to the impeller by a motor shaft. A hydrodynamic pressure bearing is installed on the motor shaft. The motor and the hydrodynamic bearing are housed in a cylindrical casing and are waterproofed by a magnetic fluid seal. The magnetic fluid seal was developed for use in an axial-flow blood pump. Sealing pressures at motor speeds of up to 10,000 rpm were measured with the seal immersed in water. The sealing pressure was above 400 mm Hg. The seal, installed in the pump, remained perfect for 60 days at a flow of 4 L/min against a pressure of 150 mmHg. Results of measurement of cell growth activity indicated that the magnetic fluid has no negative cytological effects. The developed blood pump could eject a flow of 5 L/min at a pressure difference of 100 mmHg with an allowable hemolysis level (N.I.H.<0.02). The axial flow blood pump was implanted in goats between the left ventricle and the descending aorta. The goat survived for two days and a total left ventricular bypass was obtained with the pump. A control system of the axial flow blood pump was developed. A prediction method of the pump flow based on power consumption of the motor and motor speed was proposed. Pump flow was predicted with an error of less than 10%. Backflow through the pump and obstruction of the inflow cannula were automatically detected based on the wave distortion rate of the motor current. The distortion rate was computed using the Walsh functions.
- Japan Society for the Promotion of Science：Grants-in-Aid for Scientific ResearchDate (from‐to) : 1995 -1996Author : YUHTA Toshio, NISHIMURA Ikuya, SHIMOOKA Toshiyuki, MATSUNO TakeoThe aim of this study is the long term clinical use of artificial joint by preventing wear dibris of high-density polyethylene (HDP) using "patterning" for frictional surfaces. The effect of frictional surface of the metal (SUS316L,Co-Cr alloy) vs HDP were investigated. From the results of the friction tests with the pin-on-disk experimental system, we found that the introduction of surface patterns enhances lubrication conditions between the metal) and HDP and reduces the creation of wear particles of HDP.The optimum sizes for the diameter and the pitch of the pattern were found. And good lubrication was maintained not in a short time but for a long time during the test. Based on these studies, we experimented the friction tests between the patterned femoral heads and acetabular cups with a hip simulator. In this result, we couldn's find decrease of the coefficient of friction. But the effect of patterning for good lubrication was suggested from the observation of the frictional surfaces with a light microscope. However, if the patterned head had bad condition on surface, lubrication would get worse. Therefore, we have to investigate about the good way of patterning on the surface of head and on the contact area of cup. Moreover we have to improve our simulator, for example the way of loading to friction surface. Then the problem after this are development of the new hip simulator and experiment with it again.
- 日本学術振興会：科学研究費助成事業Date (from‐to) : 1993 -1993Author : 西村 生哉現在、整形外科領域で臨床に用いられている人工関節摺動面の材質は、超高密度ポリエチレン製のソケットと、金属(SUS316L、Co-Cr合金)やセラミックス(アルミナ、ジルコニア)製のボールとの組み合せが一般的である。この摺動面が摩耗すると、人工関節の再置換をおこなわなければならなくなる。また摺動面で発生した摩耗粉は、ステムと骨との間に入り込み、ルーズニングの原因となる。研究代表者は、軸受の潤滑機構に関する研究を人工関節に応用し、人工関節摺動面の摩擦・摩耗を減少させ、その寿命を延長させることを目的として研究をおこなった。 研究代表者は、軸受の潤滑面に微細な凹凸パターンを付加することによって、潤滑特性が向上することを確認している。人工関節摺動面においても、軸受と材質は異なるが同様の効果が期待できると考え、人工関節摺動面に用いられている材質(超高密度ポリエチレン、SUS316L)を用いて潤滑実験をおこなった。まず基礎的な摩擦・摩耗実験装置を設計・試作し、表面に凹凸とパターンを付加した試料での潤滑実験の結果と、凹凸パターンを付加しない試料での潤滑実験の結果を比較した。その結果、摩擦面に凹凸パターンを付加した試料は、摩擦係数や摺動面の摩耗状態、摩擦力の安定性などの面で優れた特性を示すことが確認できた。また、パターンの形状・分布などに関して、最適な条件を得ることができた。次に上記の基礎実験結果をふまえ、実際の人工関節を模擬した摩擦・摩耗実験装置を設計・試作し、歩行状態を模擬した変動荷重を与えて潤滑実験をおこなった。その結果、臨床使用を模擬した実験でも、摺動面への凹凸パターン付加の有効性が確認された。
- Japan Society for the Promotion of Science：Grants-in-Aid for Scientific ResearchDate (from‐to) : 1989 -1991Author : YUHTA Toshio, MISHIMURA Ikuya, SHIMOOKA Toshiyuki, MURABAYASHI Shun, MITAMURA YoshinoriIn the first year ultra-duralumin was selected as a material to construct an artificial heart valve from the standpoints of price, mechanical strength, machanibility, and surface condition after machining. Stagnation and vortexes were observed in the regions distal to valve flaps and also around valve ring of commercially available valves in both computer simulation and flow visualization studies, Relatively stable flow pattern was obtained in the developed central flow-type bileaflet valve with arched flaps. Alumina was deposited on the ultra-duralumin flaps by sputtering to immprove durability and blood compatibility. Reactive sputtering deposited smoother and stronger membrane than conventional sputtering. By interposing functionally gradient material durability and adhesion of the film increased twice. In the second year valve design was determined based on fluid dynamics in both static and dynamic flow tests. The flaps are supported by pivots and inclined at the closed position. The valve has relatively large minor orifice to obtain enough secondary flow. Activation of contact coagulation factor and also platelet. Adhesion on the sputter-deposited alumina were examined. The experiments disclosed that the alumina has as good blood ompatibility as biomaterials. In the last year curvature of the flap, position of the pivol, and opening angle of the flap were determined based on static and dynamic flow tests and also flow visualization studies. The optimun curvature was 9%, pivot position 70%, and opening angle 67 degrees. The valve ring was machined from stainless steel and the surface was coated by TIN. The valve ring can also be machined from titanium. We also developed an accelerated endurance test system with the speed three times higher than other systems and also with lower water hammer pressure.
- 日本学術振興会：科学研究費助成事業Date (from‐to) : 1990 -1990Author : 勇田 敏夫, 西村 生哉, 下岡 聡行, 戸田 郁夫本研究は、効率的なル-トプレ-ニングを行うスケ-ラ-に関する基礎研究として、最適なスケ-ラ形状を決定するため、手用スケ-ラのすくい角、逃げ角を形状因子として選択した模型スケ-ラを用いて、水中に保存したヒト抜去歯を被削材として、二次元切削を行い、切削時の垂直力、水平力と切削量、表面粗さとの関係について分析解析し、効率的なル-トプレ-ニングを行い得るスケ-ラ形状について検討した。また、ル-トプレ-ニングによる歯根面形状や性状の変化が、術後の治癒率を左右するので、スケ-ラの切削条件による歯根面性状などに与える影響について検討した。以上により新たに得られた知見を要約すると、つぎの通りである。 1。臨床的な負荷のもとで、切削量、表面粗さは、切削力とほゞ線形関係にあった。 2。スケ-ラ形状において、スケ-ラ刃先のα角(被削材とすくい面のなす角)、逃げ角または刃先角が、切削量、表面粗さに有為な差をもたらすが、特にα角が大きく影響した。 3。歯根表面の滑面化と切削の効率化は、強い相関関係があるので、両立が難しいが、分散分析の結果、α角、刃先角を共に大きくとれば切削効率を落さずに、ある程度粗さを軽減できる可能性が示唆された。 4。スケ-ラのα角が大きくなると切削量が増すため歯根面の凹凸が小さくなり、表面粗さが減少する。α角が小さい場合、押込み効果が増すので、粗さの滑沢化が少ない。スメラ層はハンドスケ-ラの場合、切削条件によらず生ずる.