Thermal analysis of a miniature magnetic fluid seal installed in an implantable rotary pump
Yoshinori Mitamura, Ikuya Nishimura, Tetsuya Yano
Journal of Magnetism and Magnetic Materials, 548, 168977, 168977, Elsevier BV, Apr. 2022
Scientific journal

Shear stress evaluation on blood cells using computational fluid dynamics
Ayumi Mitoh, Yuto Suebe, Tadashi Kashima, Etaro Koyabu, Eiji Sobu, Eiji Okamoto, Yoshinori Mitamura, Ikuya Nishimura
Bio-Medical Materials and Engineering, 31, 3, 169, 178, IOS Press, 09 Jul. 2020
Scientific journal

人工心臓ハウジング内部の可視化及び形状評価に関する研究
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, 2016, 883, 884, 公益社団法人 精密工学会, 2016
Japanese, 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．

Three-dimensional shape optimization of a cemented hip stem and experimental validations
Masaru Higa, Hiromasa Tanino, Ikuya Nishimura, Yoshinori Mitamura, Takeo Matsuno, Hiroshi Ito
JOURNAL OF ARTIFICIAL ORGANS, 18, 1, 79, 85, Mar. 2015, [Peer-reviewed]
English, Scientific journal

G0200101 Evaluation of Wall Shear Stress on Cerebral Artery Using CFD
MITOH Ayumi, KOYABU Eitarou, SOBU Eiji, KASHIMA Tadashi, IKEDA Sinichi, Nishimura Ikuya, MITAMURA Yoshinori, OKAMOTO Eiji
The Proceedings of Mechanical Engineering Congress, Japan, 2015, 0, _G0200101, -_G0200101-, 一般社団法人 日本機械学会, 2015
Japanese, 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.

Evaluation of floating impeller phenomena in a Gyro centrifugal pump
Ikuya Nishimura, S. Ichikawa, M. Mikami, H. Ishitoya, T. Motomura, M. Kawamura, J. Linneweber, J. Glueck, T. Shinohara, Y. Nose
BIO-MEDICAL MATERIALS AND ENGINEERING, 23, 1-2, 49, 55, 2013, [Peer-reviewed]
English, Scientific journal

Use of a Genetic Algorithm for Multiobjective Design Optimization of the Femoral Stem of a Cemented Total Hip Arthroplasty
Toshimasa Ishida, Ikuya Nishimura, Hiromasa Tanino, Masaru Higa, Hiroshi Ito, Yoshinori Mitamura
ARTIFICIAL ORGANS, 35, 4, 404, 410, Apr. 2011, [Peer-reviewed]
English, Scientific journal

A magnetic fluid seal for rotary blood pumps: effects of seal structure on long-term performance in liquid
Yoshinori Mitamura, Sayaka Takahashi, Shuichi Amari, Eiji Okamoto, Shun Murabayashi, Ikuya Nishimura
JOURNAL OF ARTIFICIAL ORGANS, 14, 1, 23, 30, Mar. 2011, [Peer-reviewed]
English, Scientific journal

A magnetic fluid seal for rotary blood pumps: Long-term performance in liquid
Yoshinori Mitamura, Sayaka Takahashi, Shuichi Amari, Eiji Okamoto, Shun Murabayashi, Ikuya Nishimura
12TH INTERNATIONAL CONFERENCE ON MAGNETIC FLUIDS ICMF12, 9, 229, 233, 2010, [Peer-reviewed]
English, International conference proceedings

Sealing Performance of a Magnetic Fluid Seal for Rotary Blood Pumps
Yoshinori Mitamura, Sayaka Takahashi, Kentaro Kano, Eiji Okamoto, Shun Murabayashi, Ikuya Nishimura, Taka-aki Higuchi
ARTIFICIAL ORGANS, 33, 9, 770, 773, Sep. 2009, [Peer-reviewed]
English, Scientific journal

Development of hybrid total hip arthroplasty　　　　　　　　　　　　　　　
Hiroshi Ito, Takeo Matsuno, Hiromasa Tanino, Yasuhiro Yamanaka, Tatsuya Sato, Nobuyuki Oomizu, Toshiki Nakanura, Akio Minami, Ikuya Nishimura, Masara Higa
Hokkaido Journal of Orthopaedics and Traumatology, 50, 2, 190, 194, Mar. 2009
Japanese, Scientific journal

The problems in the flow estimation of the axial flow pump
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, 21 Nov. 2008
Japanese

Mechanical and Histological Evaluation of Improved Grit-Blast Implant in Dogs: Pilot Study
Leona Abe, Ikuya Nishimura, Yasuharu Izumisawa
JOURNAL OF VETERINARY MEDICAL SCIENCE, 70, 11, 1191, 1198, Nov. 2008
English, Scientific journal

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 Takeo
Transactions of the Japanese Society for Medical and Biological Engineering : BME, 46, 2, 226, 231, Japanese Society for Medical and Biological Engineering, 10 Apr. 2008
Japanese, 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 ...

Bonding strength evaluation of Cementless Implant by grit blasting
Yosuke Kozaki, Ikuya Nishimura, Yoshinori Mitamura, Shun Murabayashi, Yasuharu Izumisawa, Kouichi Kuramoto
WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING 2006, VOL 14, PTS 1-6, 14, 3251, +, 2007, [Peer-reviewed]
English, International conference proceedings

Mechanically Non-contact Axial Flow Blood Pump　　　　　　　　　　　　　　　
Y.MITAMURA, K.KIDO, T.YANO, D.SAKOTA, R.YOZU, E.OKAMOTO, S.MURABAYASHI, I.NISHIMURA
Biocybernetics and Biomedical Engineering, 27, 139, 146, 2007, [Peer-reviewed]
English

A Study of Outline Sampling Strategies for the Femoral CT Images
NISHIMURA Ikuya, ISHIDA Toshimasa, MURABAYASHI Shun, MITAMURA Yoshinori, NAKAMURA Toshiki, ITO Hiroshi, MATSUNO Takeo, HIGA Masaru, HASEI Minoru, KURAMOTO Kouichi
Transactions of Japanese Society for Medical and Biological Engineering, 44, 1, 77, 84, Japanese Society for Medical and Biological Engineering, 10 Mar. 2006
Japanese, 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.

Three-dimensional computer-aided design based design sensitivity analysis and shape optimization of the stem using adaptive p-method
H. Tanino, H. Ito, M. Higa, N. Omizu, I. Nishimura, K. Matsuda, Y. Mitamura, T. Matsuno
JOURNAL OF BIOMECHANICS, 39, 10, 1948, 1953, 2006, [Peer-reviewed]
English, Scientific journal

Stress analysis of PERFECTA IMC stem
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, 01 Oct. 2005
Japanese

Design Improvement of the Rotary Blood Pump by Computational Fluid Dynamics Analysis
YANO Tetsuya, MITOH Ayumi, MITAMURA Yoshinori, NISHIMURA Ikuya, MURABAYASHI Shun, YOZU Ryohei
Transactions of the Japanese Society for Medical and Biological Engineering : BME, 43, 1, 85, 92, Japanese Society for Medical and Biological Engineering, 10 Mar. 2005
Japanese, 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...

Effects of forms and materials of endodontic post on stress distribution : A stress analysis using three-dimensional finite element method
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, 01 Nov. 2004
Japanese

人工股関節置換後の大腿部痛発生メカニズムに関する研究(G02-4 人工関節,G02 バイオエンジニアリング部門)
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, 2004, 5, 129, 130, 一般社団法人日本機械学会, 04 Sep. 2004
Japanese, 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.

The study of relation between the angle, shape of the implant and range of motion(ROM) in THA
YAGIHASHI Kouta, MITAMURA Yoshinori, NISHIMURA Ikuya, ISHIDA Toshimasa, ITO Hiroshi, TANINO Hiromasa, NAKAMURA Toshiki, MATSUNO Takeo
IEICE technical report. ME and bio cybernetics, 104, 129, 21, 23, The Institute of Electronics, Information and Communication Engineers, 11 Jun. 2004
Japanese, 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.

Fixation to the canine bone of artificial implant with new surface structure
T Seno, Y Izumisawa, Nishimura, I, S Maehara, T Kushiro, MA Umar, S Wakaiki, K Yamashita, T Kotani
JOURNAL OF VETERINARY MEDICAL SCIENCE, 66, 3, 315, 318, Mar. 2004
English, Scientific journal

Multicriteria design optimization for an artificial hip prosthesis
Ishida Toshimasa, Ito Hiroshi, Nishimura Ikuya, Matsuno Takeo, Tanino Hiromasa, Mitamura Yoshinori
Advances in Bioengineering, BED, 301, 302, American Society of Mechanical Engineers (ASME), 2004
English, International conference proceedings

Evaluation of floating impeller phenomena in a Gyro centrifugal pump
Nishimura, I, S Ichikawa, M Mikami, H Ishitoya, T Motomura, A Kawamura, J Linneweber, J Glueck, T Shinohara, Y Nose, Nishimura, I
ASAIO JOURNAL, 49, 6, 744, 747, Nov. 2003, [Peer-reviewed]
English, Scientific journal

Development of a magnetic fluid shaft seal for an axial-flow blood pump
K Sekine, Y Mitamura, S Murabayashi, Nishimura, I, R Yozu, DW Kim
ARTIFICIAL ORGANS, 27, 10, 892, 896, Oct. 2003, [Peer-reviewed]
English, Scientific journal

Shape Optimization of an Artificial Hip Prosthesis
HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, ITOH Hiroshi, MATSUNO Takeo, MITAMURA Yoshinori
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A, 69, 679, 689, 694, The Japan Society of Mechanical Engineers, 25 Mar. 2003
Japanese, 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.

The interfacial strength in sputtering-hydroxyapatite-coating implants with Arc-deposited surface
T Seno, Y Izumisawa, Nishimura, I, S Maehara, T Yokoyama, K Yamashita, T Kotani
JOURNAL OF VETERINARY MEDICAL SCIENCE, 65, 3, 419, 422, Mar. 2003
English, Scientific journal

Shape optimization of an artificial hip prosthesis with 3D-FEM
Toshimasa Ishida, Ikuya Nishimura, Masaru Higa, Hiromasa Tanino, Hiroshi Ito, Takeo Mtasuno, Yoshinori Mitamura
American Society of Mechanical Engineers, Bioengineering Division (Publication) BED, 55, 207, 208, American Society of Mechanical Engineers (ASME), 2003, [Peer-reviewed]
English, International conference proceedings

Flow visualization study to investigate the secondary flow behind the impeller in the gyro centrifugal pump
S Ichikawa, K Nonaka, J Linneweber, S Kawahito, T Motomura, H Ishitoya, M Mikami, Nishimura, I, J Glueck, T Shinohara, Y Nose
ARTIFICIAL ORGANS, 26, 12, 1050, 1052, Dec. 2002, [Peer-reviewed]
English, Scientific journal

Influence of stem shape on stress of the bone cement mantle in femoral hip component
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, 01 Nov. 2002
Japanese

Titania gel reduces thrombin generation
H Ishitoya, M Kawamura, J Linneweber, T Motomura, S Ichikawa, Nishimura, I, J Glueck, T Shinohara, Y Nose
ARTIFICIAL ORGANS, 26, 11, 959, 963, Nov. 2002, [Peer-reviewed]
English, Scientific journal

Shape opimization of femoral components of an artificial hip prosthesis using the three-dimensional p-version finite element study and the in vitro measurement of strain in the bone cement　　　　　　　　　　　　　　　
Masaru Higa, Ikuya Nishimura, Kazuhiro Matsuda, Hiromasa Tanino, Yoshinori Mitamura
ASME International Mechanical Engineering Congress and Exposition, Proceedings, 339, 340, American Society of Mechanical Engineers (ASME), 2002
English, International conference proceedings

Shape opimization of femoral components of an artificial hip prosthesis using the three-dimensional P-version finite element method　　　　　　　　　　　　　　　
Masaru Higa, Ikuya Nishimura, Hiromasa Tanino, Yoshinori Mitamura
American Society of Mechanical Engineers, Bioengineering Division (Publication) BED, 51, 25, 26, 2001
English, International conference proceedings

The sphericity of the bearing surface in total hip arthroplasty
Hiroshi Ito, Akio Minami, Takeo Matsuno, Hiromasa Tanino, Toshio Yuhta, Ikuya Nishimura
Journal of Arthroplasty, 16, 8, 1024, 1029, Churchill Livingstone Inc., 2001, [Peer-reviewed]
English, Scientific journal

Reduction of polyethylene wear by concave dimples on the frictional surface in artificial hip joints
H Ito, K Kaneda, T Yuhta, Nishimura, I, K Yasuda, T Matsuno
JOURNAL OF ARTHROPLASTY, 15, 3, 332, 338, Apr. 2000
English, Scientific journal

The outline sampling strategies for the femoral CT images　　　　　　　　　　　　　　　
I. Nishimura, T. Ishida, S. Murabayashi, Y. Mitamura, T. Nakamura, H. Ito, T. Matsuno, M. Higa, M. Hasei, K. Kuramoto
Proceeding of World Congress on Medical Physics and Biomedical Engineering, 14, 2441, 2444, [Peer-reviewed]
English, International conference proceedings

G0200305 Clear up the cause for thigh pain after cementless hip replacement
NISHIMURA Ikuya, MITOH Ayumu, ANAGUCHI Yuko, Mechanical Engineering Congress, Japan, 2015, "G0200305, 1"-"G0200305-4", 13 Sep. 2015
A 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., The Japan Society of Mechanical Engineers, Japanese

FLEXOR ACTIVITY BY INTRAMEDULLARY PRESSURE IN RABBIT FEMORAL BONE: An experimental study on thigh pain after total hip arthroplasty
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, Feb. 2013
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., English

北海道における人工関節置換術の現状と課題
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, Mar. 2009
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。, Japanese

1233 Multicriteria design optimization for an artificial hip joint
Ishida Toshimasa, Nishimura Ikuya, Tanino Hiromasa, Ito Hiroshi, Matsuno Takeo, Mitamura Yoshinori, The proceedings of the JSME annual meeting, 2005, 5, 207, 208, 18 Sep. 2005
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..., The Japan Society of Mechanical Engineers, Japanese

Development of canine artificial hip prosthesis
Higa Masaru, Nishimura Ikuya, Maeda Fuyuhiko, Seno Takahiro, Izumisawa Yasuharu, Mitakura Yoshinori, The proceedings of the JSME annual meeting, 2004, 5, 127, 128, 04 Sep. 2004
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..., The Japan Society of Mechanical Engineers, Japanese

Estimation of Hemolysis within Continuous Flow Blood Pump by Computational Fluid Dynamics Analysis
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, 04 Sep. 2004
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 ..., The Japan Society of Mechanical Engineers, Japanese

11.有限要素法を用いた人工股関節ステム形状の検討(平成15年度北海道支部大会抄録)
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, 10 Jun. 2004
社団法人日本生体医工学会, Japanese

A Magnetic Fluid Shaft Seal for Blood Pumps
Sekine Kazumitsu, Mitamura Yoshinori, Murabayashi Shun, Nishimura Ikuya, Yozu Ryohei, The proceedings of the JSME annual meeting, 2003, 5, 95, 96, 05 Aug. 2003
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 ..., The Japan Society of Mechanical Engineers, Japanese

A Study of Thigh Pain in Uncemented Total Hip Arthroplasty
SHIMIZU Ryota, NISHIMURA Ikuya, NAKAMURA Toshiki, MATSUNO Takeo, MITAMURA Yoshinori, The proceedings of the JSME annual meeting, 2003, 7, 141, 142, 05 Aug. 2003
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., The Japan Society of Mechanical Engineers, Japanese

10.血液透析療法におけるブラッドアクセス監視システムの開発における基礎的研究(平成14年度北海道支部大会抄録)
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, 10 Mar. 2003
社団法人日本生体医工学会, Japanese

Shape optimization of cemented total hip arthroplasty
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, 20 Jan. 2003
The Japan Society of Mechanical Engineers, Japanese

An Estimation Method of Hemolysis within an Axial Flow Blood Pump by Computational Fluid Dynamics (CFD) Analysis
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

Shape Optimization of Artificial Hip Prosthesis with 3D-FEM
Ishida Toshimasa, Nishimura Ikuya, Higa Masaru, Mitamura Yoshinori, The proceedings of the JSME annual meeting, 2002, 6, 53, 54, 20 Sep. 2002
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..., The Japan Society of Mechanical Engineers, Japanese

Shape Optimization of Artificial Hip Prosthesis with 3D FEM
HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, ITOH Hiroshi, MATSUNO Takeo, MITAMURA Yoshinori, Journal of the Japan Society for Precision Engineering, 68, 7, 948, 952, 05 Jul. 2002
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., The Japan Society for Precision Engineering, Japanese

Computer Image Analysis for Measuring Color of Teeth
SATOH Shunsuke, MITAMURA Yoshinori, HIRAYAMA Yasushi, YUHTA Toshio, NISHIMURA Ikuya, IEICE technical report. ME and bio cybernetics, 102, 137, 9, 12, 14 Jun. 2002
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., The Institute of Electronics, Information and Communication Engineers, Japanese

新たなporous surfaceを有するチタン製Implantの骨固着効果(組織学的検討)
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, 10 Jun. 2002
Japanese

ボーンイングロースを促進する新しいポーラス構造表面の開発に関する研究
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, 01 Mar. 2002
Japanese

F-0927 Shape optimization of cemented stem at Total Hip Arthroplasty
Matsuda Kazuhiro, Nisimura Ikuya, Tanino Hiromasa, Higa Masaru, Mitamura Yosinori, The proceedings of the JSME annual meeting, 0, 1, 79, 80, 22 Aug. 2001
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..., The Japan Society of Mechanical Engineers, Japanese

Total Hip Arthroplasty : Dream for Unloosened THA
Matsuno Takeo, Asahikawa Medical College research bulletin, 2, 1, 30, 35, 30 Jun. 2001
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, Asahikawa Medical College, Japanese

Shape Optimization of 3D CAD based model of stem at Total Hip Arthroplasty with p-Adaptivity
Matuda Kazuhiro, Nisimura Ikuya, Tanino Hiromasa, Higa Masaru, Mitamura Yosinori, IEICE technical report. ME and bio cybernetics, 101, 130, 9, 14, 15 Jun. 2001
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..., The Institute of Electronics, Information and Communication Engineers, Japanese

Shape Optimization of an Artificial Hip Prosthesis using a 3D CAD model
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, 15 Jan. 2001
The Japan Society of Mechanical Engineers, Japanese

A Study on Improvement of Lubrication Properties for the Frictional Surfaces of the Artificial Joints
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, 05 Oct. 2000
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., The Japan Society for Precision Engineering, Japanese

コンピュータシミュレーションによるBone ingrowth能の解析
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, 01 Sep. 2000
Japanese

Sphericity of the Bearing Surface in Total Hip Arthroplasty
ITO H, 日本整形外科學會雜誌, 74, 8, S1661, 25 Aug. 2000
Japanese

Design Sensitivity Analysis of the Artificial Hip Joint Using P-version Finite Element Method
HIGA M, 日本整形外科學會雜誌, 74, 8, S1783, 25 Aug. 2000
Japanese

The Effect of the Proxi-medial Cemented Stem Geometry on the Stress Distribution
OMIZU N, 日本整形外科學會雜誌, 74, 8, S1784, 25 Aug. 2000
Japanese

Shape Optimization of a Hip Prosthesis with p Adaptivity
HIGA Masaru, NISHIMURA Ikuya, TANINO Hiromasa, MITAMURA Yoshinori, The proceedings of the JSME annual meeting, 2000, 2, 61, 62, 31 Jul. 2000
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., The Japan Society of Mechanical Engineers, Japanese

臼蓋形成不全に対する骨移植と金属置換の応力解析
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, 25 Aug. 1999
Japanese

人工股関節摺動画の真球度と凹凸パターン形成
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, 25 Aug. 1999
Japanese

Improvement of Lubrication Properties for New Surface Structure with Regular Patterning for the Frictional Surfaces of the Artificial Joints
NISHIMURA Ikuya, YUHTA Toshio, ITOH Hiroshi, HIRAYAMA Mitsuhisa, SHIKATA Jitsuto, TANINO Hiromasa, MATSUNO Takeshi, 生体材料, 16, 5, 254, 259, 10 Oct. 1998
Japanese

機能的表面構造を持つ人工関節に関する研究
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, 01 Sep. 1998
Japanese

Formation of Concave-convex Pattern on the Sliding Surface in Total Joint Arthroplasty
ITO H, 日本整形外科學會雜誌 = The Journal of the Japanese Orthopaedic Association, 72, 8, S1287, 25 Aug. 1998
Japanese

Improvement in wear durability of friction surface of artificial hip joint
SHIKATA Jitsuto, NISHIMURA Ikuya, SHIMOOKA Toshiyuki, YUHTA Toshio, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 97, 622, 9, 14, 20 Mar. 1998
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..., The Institute of Electronics, Information and Communication Engineers, Japanese

The Sphericity of the Bearing Surface in Total Hip Arthroplasty
ITO H, 日本整形外科學會雜誌 = The Journal of the Japanese Orthopaedic Association, 71, 8, 1785, 1785, 25 Aug. 1997
Japanese

加速耐久試験における人工弁の壊食評価に関する研究
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, 01 Mar. 1997
Japanese

キャビテーションによる人工弁の壊食に関する研究
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, 01 Sep. 1996
Japanese

反応性スパッタ蒸着法による生体用金属材料の表面改質に関する基礎的研究(第1報)
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, 01 Mar. 1996
Japanese

Improvement of the Frictional Surfaces of the Artificial Joint
NISHIMURA Ikuya, YUHTA Toshio, ITOH Hiroshi, KISIMOTO Takafumi, GOTOH Ryuuji, MATSUNO Takeo, KANEDA Kiyoshi, 生体材料, 13, 6, 266, 271, 01 Dec. 1995
Japanese

Surface Modification of Polymer by Deposition of Thin Inorganic Films
NISHIMURA Ikuya, YUHTA Toshio, MATSUBARA Yoshihiro, Journal of the Japan Society of Precision Engineering, 61, 4, 576, 580, 05 Apr. 1995
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..., The Japan Society for Precision Engineering, Japanese

BLOOD COMPATIBILITY OF SPUTTER-DEPOSITED ALUMINA FILMS
T YUHTA, Y KIKUTA, Y MITAMURA, K NAKAGANE, S MURABAYASHI, NISHIMURA, I, JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, 28, 2, 217, 224, Feb. 1994
English

A Primary Study of the Antithrombogenesis of Deposited Alumina Film by Reactive Sputtering : Effect of Oxygen Partial Pressure in Sputtering
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, Oct. 1992
北海道大学 = Hokkaido University, Japanese

Study On Characteristics of Lubrication by Sliding Surface Structure
西村 生哉, 勇田 敏夫, 斉藤 剛, Bulletin of the Faculty of Engineering,Hokkaido University, 158, p87, 94, Jan. 1992
北海道大学 = Hokkaido University, Japanese

Influence of Nitrogen Gas Partial Pressure on the Properties of TiN Deposited by Reactive Sputter Deposition.
NISHIMURA Ikuya, YUHTA Toshio, SAITOH Tsuyoshi, Journal of the Surface Finishing Society of Japan, 43, 6, 584, 588, 1992
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..., The Surface Finishing Society of Japan, Japanese

改訂 臨床工学技士のための機械工学　　　　　　　　　　　　　　　
西村生哉
Sep. 2022

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
Jul. 2017

臨床工学技士のための電気工学　　　　　　　　　　　　　　　
西村生哉
2014, [Single work]

臨床工学技士のための機械工学　　　　　　　　　　　　　　　
西村生哉
Jan. 2013, [Single work]

臨床工学技士のための生体物性　　　　　　　　　　　　　　　
村林 俊
Jun. 2012, [Supervisor]

超精密生産技術大系、第4巻 第6編　　　　　　　　　　　　　　　
第2章 第4節、人工骨
株式会社フジ・テクノシステム, Feb. 1996, [Joint work]

Development of an axial flow blood pump using a hydrodynamic pressure bearing
Grants-in-Aid for Scientific Research
2002 - 2005
MITAMURA Yoshinori, MURABAYASHI Shun, NISHIMURA Ikuya, OKAMOTO Eiji, YOZU Rhohei, YAMBE Tomoyuki
An 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, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 14380386

Fundamental Study on Improvement of Artificial Joint with the Functional Surface structure
Grants-in-Aid for Scientific Research
1995 - 1996
YUHTA Toshio, NISHIMURA Ikuya, SHIMOOKA Toshiyuki, MATSUNO Takeo
The 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.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 07458233

人工関節摺動面の潤滑特性向上に関する基礎的研究
科学研究費助成事業
1993 - 1993
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。
日本学術振興会, 奨励研究(A), 北海道大学, 05780642

Development of a low-priced artificial heart, valve with high valvular functions
Grants-in-Aid for Scientific Research
1989 - 1991
YUHTA Toshio, MISHIMURA Ikuya, SHIMOOKA Toshiyuki, MURABAYASHI Shun, MITAMURA Yoshinori
In 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.
Japan Society for the Promotion of Science, Grant-in-Aid for Developmental Scientific Research, Hokkaido University, 01890001

効率的なル-トプレ-ニングを行うスケ-ラ-に関する基礎的研究
科学研究費助成事業
1990 - 1990
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.
日本学術振興会, 一般研究(B), 北海道大学, 02455002