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9 results on '"Hiroaki Koh"'

1. High-Strength Porous Copper by Cold-Extrusion

Author

Hiroaki Koh, Hiroshi Utsunomiya, Tetsuo Sakai, and Jyoji Miyamoto

Subjects
Materials science, Composite number, Metallurgy, chemistry.chemical_element, Metal foam, Condensed Matter Physics, Copper, Metal, chemistry, Transition metal, Aluminium, visual_art, visual_art.visual_art_medium, General Materials Science, Extrusion, Porosity
Abstract

The authors propose a method to fabricate porous metals with high strength in this paper. Pieces of matrix metal and space-holder metal are deformed together by bulk forming for solid-phase bonding. From the bonded composite, only the space-holder metal is removed. If the deformation and the removal are conducted at cold or warm region, 'wrought' high-strength porous metal can be obtained. In this study, using aluminum as space holder, two types of porous copper with one-dimensional pores, i.e., lotus-type and honeycomb-type rods, have been successfully fabricated by cold extrusion followed by chemical leaching. Both the porous coppers fabricated show higher specific yield strength than a conventional porous metal.

Published
2008
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2. Texture of AZ31 Magnesium Alloy Sheet Heavily Rolled by High Speed Warm Rolling

Author

Tetsuo Sakai, Hiroaki Koh, Hiroshi Utsunomiya, and Satoshi Minamiguchi

Subjects
Cracking, Materials science, Mechanics of Materials, Mechanical Engineering, Metallurgy, General Materials Science, Texture (crystalline), Magnesium alloy, Condensed Matter Physics, Ductility, Raising (metalworking), Shear band, Rolling speed
Abstract

Magnesium alloy sheets had to be rolled at elevated temperature to avoid cracking. The poor workability of magnesium alloy is ascribed to its hcp crystallography and insufficient activation of independent slip systems. Present authors have succeeded in 1-pass heavy rolling of AZ31 magnesium alloy sheet below 473K by raising rolling speed above 1000m/min. Heavy reduction larger than 60% can be applied by 1-pass high speed rolling even at room temperature. The improvement of workability at lower rolling temperature is due to temperature rise by plastic working. The texture of heavily rolled AZ31 magnesium alloy sheet is investigated in the present study. The texture of sheets rolled 60% at room temperature was //ND basal texture. At the rolling temperature above 373K, the peak of (0001) pole tilted ±10-15 deg toward RD direction around TD axisto form a double peak texture. The texture varied through thickness. At the surface, the (0001) peak tilted ±10-15 deg toward TD direction around RD axis to form a TD-split double peak texture. The direction of (0001) peak splitting rotated 90 deg from the surface to the center of thickness. Heavily rolled magnesium alloy sheets have non-basal texture. The sheets having non-basal texture are expected to show better ductility than sheets with basal texture.

Published
2007
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3. Fabrication of Porous Copper by Cold Extrusion and Leaching

Author

Jouji Miyamoto, Hiroshi Utsunomiya, Tetsuo Sakai, and Hiroaki Koh

Subjects
Materials science, Fabrication, Metallurgy, Composite number, Metals and Alloys, chemistry.chemical_element, Condensed Matter Physics, Copper, Physics::Geophysics, Computer Science::Other, Condensed Matter::Materials Science, Compressive strength, chemistry, Mechanics of Materials, Aluminium, Materials Chemistry, Extrusion, Leaching (metallurgy), Porosity
Abstract

Conventional porous metals show relatively low strength due to softening in high-temperature treatments such as casting or bubbling. In the current study, the authors propose an alternative method to fabricate high-strength porous metals using cold working. A copper pipe filled with Cu and Al wires was deformed by cold extrusion to solid-phase bonding. From the Cu/Al composite, only aluminum is removed chemically by NaOH solution leaching to produce porous copper with one-dimensional pores. The porous copper fabricated shows outstanding compressive yield strength than conventional porous copper.

Published
2007
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4. Deformation and Texture Evolution during High-Speed Rolling of AZ31 Magnesium Sheets

Author

Tetsuo Sakai, Hiroaki Koh, Satoshi Minamiguchi, and Hiroshi Utsunomiya

Subjects
Equiaxed crystals, Materials science, Mechanical Engineering, Metallurgy, Deformation (meteorology), Condensed Matter Physics, Microstructure, Grain size, Shear (sheet metal), Mechanics of Materials, General Materials Science, Surface layer, Texture (crystalline), Ductility
Abstract

Deformation of AZ31 sheets during high-speed rolling at various temperatures was investigated. The thickness of 2.5 mm was reduced 60% by single-pass operation at a speed of 2000 m/min. Textures, microstructures, mechanical properties and bendability of the sheets processed were examined. In the sheets rolled at elevated temperature, equiaxed fine grains (

Published
2007
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5. Abstracts

Author

W. A. C. Mutch, I. W. C. White, N. Donen, I. R. Thomson, M. Rosenbloom, M. Cheang, M. West, Greg Bryson, Christina Mundi, Jean-Yves Dupuis, Michael Bourke, Paul McDonagh, Michael Curran, John Kitts, J. Earl Wynands, Alison S. Carr, Elizabeth J. Hartley, Helen M. Holtby, Peter Cox, Bruce A. Macpherson, James E. Baker, Andrew J. Baker, C. David Mazer, C. Peniston, T. David, D. C. H. Cheng, J. Karski, B. Asokumar, J. Carroll, H. Nierenberg, S. Roger, A. N. Sandier, J. Tong, C. M. Feindel, J. F. Boylan, S. J. Teasdale, J. Boylan, P. Harley, Jennifer E. Froelich, David P. Archer, Alastair Ewen, Naaznin Samanani, Sheldon H. Roth, Richard I. Hall, Michael Neumeister, Gwen Dawe, Cathy Cody, Randy O’Brien, Jan Shields-Thomson, Kenneth M. LeDez, Catherine Penney, Walter Snedden, John Tucker, Nicolas Fauvel, Mladen Glavinovic, François Donati, S. B. Backman, R. D. Stein, C. Polosa, C. Abdallah, S. Gal, A. John Clark, George A. Doig, Tunde Gondocz, E. A. Peter, A. Lopez, A. Mathieu, Pierre Couture, Daniel Boudreault, Marc Derouin, Martin Allard, Gilbert Blaise, Dominique Girard, Richard L. Knill, Teresa Novick, Margaret K. Vandervoort, Frances Chung, Shantha Paramanathar, Smita Parikh, Charles Cruise, Christina Michaloliakou, Brenda Dusek, D. K. Rose, M. M. Cohen, D. DeBoer, George Shorten, Earnest Cutz, Jerrold Lerman, Myrna Dolovich, Edward T. Crosby, Robert Cirone, Dennis Reid, Joanne Lind, Melanie Armstrong, Wanda Doyle, S. Halpern, P. Glanc, T. Myhr, M -L. Ryan, K. Fong, K. Amankwah, A. Ohlsson, R. Preston, Andor Petras, Michael J. Jacka, Brian Milne, Kanji Nakatsu, S. Pancham, Graeme Smith, Kush N. Duggal, M. Joanne Douglas, Pamela M. Merrick, Philip Blew, Donald Miller, Raymond Martineau, Kathryn Hull, C. M. Baron, S. Kowalskl, R. Greengrass, T. Horan, H. Unruh, C. L. Baron, Patricia M. Cruchley, K. Nakajima, Y. Sugiura, Y. Goto, K. Takakura, J. Harada, Robert M. K. W. Lee, Angelica M. Fargas-Babjak, Jin Ni, Eva S. Werstiuk, Joseph Woo, David H. Morison, Michael D. McHugh, Hanna M. Pappius, Hironori Ishihara, Yuki Shimodate, Hiroaki Koh, Akitomo Matsuki, John W. R. Mclntyre, Pierre Bergeron, Lulz G. R. DeLima, Jean-Yves Dupuls, James Enns, J. M. Murkin, F. N. McKenzie, S. White, N. A. Shannon, Wojciech B. Dobkowski, Judy L. Kutt, Bernard J. Mezon, David R. Grant, William J. Wall, Dennis D. Doblar, Yong C. Lim, Luc Frenette, Jaime R. Ronderos, Steve Poplawski, Dinesh Ranjan, L. Dubé, L. Van Obbergh, M. Francoeur, C. Blouin, R. Carrier, D. Doblar, J. Ronderos, D. Singer, J. Cox, B. Gosdin, M. Boatwright, Charles E. Smith, Aleksandr Rovner, Carlos Botero, Curt Holbrook, Nileshkumar Patel, Alfred Pinchak, Alfred C. Pinchak, Yin James Kao, Andrew Thio, Steven J. Barker, Patrick Sullivan, Matthew Posner, C. William Cole, Patty Lindsay, Paul B. Langevin, Paul A. Gulig, N. Gravenstein, David T. Wong, Manuel Gomez, Glenn P. McGuire, Robert J. Byrick, Shared K. Sharma, Frederick J. Carmicheal, Walter J. Montanera, Sharad Sharma, D. A. Yee, Basem I. Naser, G. L. Bryson, J. B. Kitts, D. R. Miller, R. J. Martineau, M. J. Curran, P. R. Bragg, Jacek M. Karski, Davy Cheng, Kevin Bailey, S. Levytam, R. Arellano, J. Katz, J. Doyle, Mitchel B. Sosis, William Blazek, G. Plourde, A. Malik, Tammy Peddle, James Au, Jeffrey Sloan, Mark Cleland, Donald E. Hancock, Nilesh Patel, Frank Costello, Louise Patterson, Masao Yamashita, Tsukasa Kondo, M. R. Graham, D. Thiessen, David F. Vener, Thomas Long, S. Marion, D. J. Steward, Berton Braverman, Mark Levine, Steve Yentis, Catherine R. Bachman, Murray Kopelow, Ann McNeill, R. Graham, Norbert Froese, Leena Patel, Heinz Reimer, Jo Swartz, Suzanne Ullyot, Harley Wong, Maria A. Markakis, Nancy Siklch, Blair D. Goranson, Scott A. Lang, Martin J. Stockwell, Bibiana Cujec, Raymond W. Yip, Lucy C. Southeriand, Tanya Duke B. Vet, Jeisane M. Gollagher, Lesley-Ann Crone, James G. Ferguson, Demetrius Litwin, Maria Bertlik, Beverley A. Orser, Lu-Wang Yang, John F. MacDonald, Gary F. Morris, Wendy L. Gore-Hickman, J. E. Zamora, O. P. Rosaeg, M. P. Lindsay, M. L. Crossan, Carol Pattee, Michael Adams, John P. Koller, Guy J. Lavoie, Wynn M. Rigal, Dylan A. Taylor, Michael G. Grace, Barry A. Flnegan, Christopher Hawkes, Harry Hopkins, Michael Tierney, David R. Drover, Gordon Whatley, J. W. Donald Knox, Jarmila Rausa, Hossam El-Beheiry, Ronald Seegobin, Georgia C. Hirst, William N. Dust, J. David Cassidy, D. Boisvert, H. Braden, M. L. Halperin, S. Cheema-Dhadli, D. J. McKnight, W. Singer, Thomas Elwood, Shirley Huchcroft, Charles MacAdams, R. Peter Farran, Gerald Goresky, Phillip LaLande, Gilles Lacroix, Martin Lessard, Claude Trépanier, Janet M. van Vlymen, Joel L. Parlow, Chikwendu Ibebunjo, Arnold H. Morscher, Gregory J. Gordon, H. P. Grocott, Susan E. Belo, Georgios Koutsoukos, Susan Belo, David Smith, Sarah Henderson, Adriene Gelb, G. Kantor, N. H. Badner, W. E. Komar, R. Bhandari, D. Cuillerier, W. Dobkowski, M. H. Smith, A. N. Vannelli, Sean Wharton, Mike Tierney, E. Redmond, E. Reddy, A. Gray, J. Flynn, R. B. Bourne, C. H. Rorabeck, S. J. MacDonald, J. A. Doyle, Peter T. Newton, Carol A. Moote, R. Joiner, M. F. X. Glynn, Vytas Zulys, M. Hennessy, T. Winton, W. Demajo, William P. S. McKay, Peter H. Gregson, Benjamin W. S. McKay, Julio Militzer, Eric Hollebone, Raymond Yee, George Klein, R. L. Garnett, J. Conway, F. E. Ralley, G. R. Robbins, James E. Brown, J. V. Frei, Edward Podufal, Norman J. Snow, Altagracia M. Chavez, Richard P. Kramer, D. Mickle, William A. Tweed, Bisharad M. Shrestha, Narendra B. Basnyat, Bhawan D. Lekhak, Susan D. O’Leary, J. K. Maryniak, John H. Tucker, Cameron B. Guest, J. Brendan Mullen, J. Colin Kay, Dan F. Wigglesworth, Mashallah Goodarzi, Nicte Ha Shier, John A. Ogden, O. R. Hung, S. Pytka, M. F. Murphy, B. Martin, and R. D. Stewart

Subjects
Anesthesiology and Pain Medicine, General Medicine
Published
1994
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7. [A clinical study of total intravenous anesthesia by using mainly propofol, fentanyl and ketamine--with special reference to its safety based on 26,079 cases]

Author

Akitomo, Matsuki, Hironori, Ishihara, Naoki, Kotani, Tetsuhiro, Sakai, Kazuyoshi, Hirota, Masatoshi, Muraoka, Hiroshi, Hashimoto, Toshihito, Tsubo, Satoshi, Takahashi, Hiroaki, Koh, Shigeharu, Wakayama, Yutaka, Sato, and Hirobumi, Nagao

Subjects
Adult, Aged, 80 and over, Adolescent, Cardiovascular Surgical Procedures, Infant, Middle Aged, Anesthetics, Combined, Neurosurgical Procedures, Fentanyl, Child, Preschool, Anesthesia, Intravenous, Humans, Ketamine, Safety, Child, Propofol, Aged
Abstract

During a period of five years from January 1996 through December 2000 total intravenous anesthesia with mainly propofol, fentanyl and ketamine was administered to 26,079 patients including cardiac and neurosurgical patients at the University of Hirosaki Hospital and five other affiliated hospitals. The patients studied ranged from 1 year 8 months to 93 years in age, 9.2 kg to 135.0 kg in body weight and from 18 min to 22 hours 50 min in anesthetic time. With adequate monitoring, fentanyl 1-2 micrograms.kg-1 was given at first, then total-dose of ketamine 1 mg.kg-1 and propofol 1-2 mg.kg-1 were administered for the induction of anesthesia in adult patients. A total dose of fentanyl 3-15 micrograms.kg-1 was given combined with propofol 5-10 mg.kg-1 and ketamine 0.3-1.0 mg.kg.h-1. In craniotomy patients, ketamine was excluded. For pediatric patients, sevoflurane anesthesia was employed to establish i.v. route, and intravenous agents were given almost same as in the same manner as in adult patients. None of them developed either cardiac arrest or severe cardiovascular insufficiencies due to anesthesia alone. Their postoperative hepatic and renal functions evaluated by various biochemical indices and urine output were adequately maintained during anesthesia and for a week postoperatively. They were followed up to 3 months postoperatively only to fail to detect any adverse events related directly to this method of anesthesia. These data suggest that total intravenous anesthesia with propofol, fentanyl and ketamine has a very wide margin of safety.

Published
2003

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