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Ishikawa H, Imajo S, Takeda H, Kakegawa M, Yamashita M, Yamaura JI, Kindo K. J_{eff}=1/2 Hyperoctagon Lattice in Cobalt Oxalate Metal-Organic Framework. Phys Rev Lett 2024; 132:156702. [PMID: 38682962 DOI: 10.1103/physrevlett.132.156702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/22/2024] [Accepted: 03/01/2024] [Indexed: 05/01/2024]
Abstract
We report the magnetic properties of a cobalt oxalate metal-organic framework featuring the hyperoctagon lattice. Our thermodynamic measurements reveal the J_{eff}=1/2 state of the high-spin Co^{2+} (3d^{7}) ion and the two successive magnetic transitions at zero field with two-stage entropy release. ^{13}C-NMR measurements reveal the absence of an internal magnetic field in the intermediate temperature phase. Multiple field-induced phases are observed before full saturation at around 40 T. We argue the unique cobalt oxalate network gives rise to the Kitaev interaction and/or a bond frustration effect, providing an unconventional platform for frustrated magnetism on the hyperoctagon lattice.
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Affiliation(s)
- Hajime Ishikawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Shusaku Imajo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Hikaru Takeda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Masafumi Kakegawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Minoru Yamashita
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Jun-Ichi Yamaura
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Koichi Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
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2
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Imajo S, Miyake A, Kurihara R, Tokunaga M, Kindo K, Horiuchi S, Kagawa F. Quantum Liquid States of Spin Solitons in a Ferroelectric Spin-Peierls State. Phys Rev Lett 2024; 132:096601. [PMID: 38489634 DOI: 10.1103/physrevlett.132.096601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 01/31/2024] [Indexed: 03/17/2024]
Abstract
In this study, we performed high-magnetic-field magnetization, dielectric, and ultrasound measurements on an organic salt showing a ferroelectric spin-Peierls (FSP) state, which is in close proximity to a quantum critical point. In contrast to the sparsely distributed gaslike spin solitons typically observed in conventional spin-Peierls (SP) states, the FSP state exhibits dense liquidlike spin solitons resulting from strong quantum fluctuations, even at low fields. Nevertheless, akin to conventional SP systems, a magnetic-field-induced transition is observed in the FSP state. In conventional high-field SP states, an emergent wave vector results in the formation of a spin-soliton lattice. However, in the present high-field FSP state, the strong quantum fluctuations preclude the formation of such a soliton lattice, causing the dense solitons to remain in a quantum-mechanically melted state. This observation implies the realization of a quantum liquid-liquid transition of topological particles carrying spin and charge in a ferroelectric insulator.
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Affiliation(s)
- Shusaku Imajo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Atsushi Miyake
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
| | - Ryosuke Kurihara
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Masashi Tokunaga
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Koichi Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Sachio Horiuchi
- Research Institute of Advanced Electronics and Photonics (RIAEP), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
| | - Fumitaka Kagawa
- Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
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3
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Takehara R, Kubo N, Ryu M, Kitani S, Imajo S, Shoji Y, Kawaji H, Morikawa J, Fukushima T. Insights into Thermal Transport through Molecular π-Stacking. J Am Chem Soc 2023; 145:22115-22121. [PMID: 37756122 PMCID: PMC10571076 DOI: 10.1021/jacs.3c07921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Indexed: 09/29/2023]
Abstract
π-Stacking, which is a ubiquitous structural motif in assemblies of aromatic compounds, is well-known to provide a transport pathway for charge carriers and excitons, while its contribution to thermal transport is still unclear. Herein, based on detailed experimental observations of the thermal diffusivity, thermal conductivity, and specific heat of a single-crystalline triphenylene featuring a one-dimensionally π-stacked structure, we describe the nature of thermal transport through the π-stacked columns. We reveal that acoustic phonons are responsible for thermal transport through the π-stacked columns, which exhibit crystal-like behavior. Importantly, the thermal energy stored as intramolecular vibrations can also be transported by coupling to the acoustic phonons. In contrast, in the direction perpendicular to the π-stacked columns, an amorphous-like thermal transport behavior dominates. The present finding offers deep insight into nanoscale thermal transport in organic materials, where the constituent molecules exist as discrete entities linked together by weak intermolecular interactions.
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Affiliation(s)
- Ryosuke Takehara
- Laboratory
for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Natsuki Kubo
- Laboratory
for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Meguya Ryu
- National
Methodology Institute of Japan (NMIJ), Advanced
Industrial Science and Technology (AIST), Tsukuba Central 3, 1-1-1 Umezono, Tsukuba 305-8563, Japan
| | - Suguru Kitani
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Shusaku Imajo
- Institute
for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yoshiaki Shoji
- Laboratory
for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Hitoshi Kawaji
- Laboratory
for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Junko Morikawa
- Department
of Materials Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Living Systems
Materialogy (LiSM) Research Group, International Research Frontiers
Initiative (IRFI), Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Takanori Fukushima
- Laboratory
for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
- Living Systems
Materialogy (LiSM) Research Group, International Research Frontiers
Initiative (IRFI), Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
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4
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Čulo M, Licciardello S, Ishida K, Mukasa K, Ayres J, Buhot J, Hsu YT, Imajo S, Qiu MW, Saito M, Uezono Y, Otsuka T, Watanabe T, Kindo K, Shibauchi T, Kasahara S, Matsuda Y, Hussey NE. Expanded quantum vortex liquid regimes in the electron nematic superconductors FeSe 1-xS x and FeSe 1-xTe x. Nat Commun 2023; 14:4150. [PMID: 37438333 DOI: 10.1038/s41467-023-39730-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/21/2023] [Indexed: 07/14/2023] Open
Abstract
The quantum vortex liquid (QVL) is an intriguing state of type-II superconductors in which intense quantum fluctuations of the superconducting (SC) order parameter destroy the Abrikosov lattice even at very low temperatures. Such a state has only rarely been observed, however, and remains poorly understood. One of the key questions is the precise origin of such intense quantum fluctuations and the role of nearby non-SC phases or quantum critical points in amplifying these effects. Here we report a high-field magnetotransport study of FeSe1-xSx and FeSe1-xTex which show a broad QVL regime both within and beyond their respective electron nematic phases. A clear correlation is found between the extent of the QVL and the strength of the superconductivity. This comparative study enables us to identify the essential elements that promote the QVL regime in unconventional superconductors and to demonstrate that the QVL regime itself is most extended wherever superconductivity is weakest.
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Affiliation(s)
- M Čulo
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
- Institut za fiziku, Bijenička cesta 46, HR-10000, Zagreb, Croatia.
| | - S Licciardello
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands
| | - K Ishida
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - K Mukasa
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - J Ayres
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - J Buhot
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - Y-T Hsu
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands
- Center for Theory and Computation, National Tsing Hua University, No. 101, Section. 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - S Imajo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - M W Qiu
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - M Saito
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Y Uezono
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - T Otsuka
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - T Watanabe
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - K Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - S Kasahara
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushimanaka, Kita-Ku, Okayama, 700-8530, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Sakyo-Ku, Kyoto, 606-8502, Japan
| | - N E Hussey
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
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5
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Nomoto T, Imajo S, Akutsu H, Nakazawa Y, Kohama Y. Correlation-driven organic 3D topological insulator with relativistic fermions. Nat Commun 2023; 14:2130. [PMID: 37080975 PMCID: PMC10119126 DOI: 10.1038/s41467-023-37293-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 03/09/2023] [Indexed: 04/22/2023] Open
Abstract
Exploring new topological phenomena and functionalities induced by strong electron correlation has been a central issue in modern condensed-matter physics. One example is a topological insulator (TI) state and its functionality driven by the Coulomb repulsion rather than a spin-orbit coupling. Here, we report a 'correlation-driven' TI state realized in an organic zero-gap system α-(BETS)2I3. The topological surface state and chiral anomaly are observed in temperature and field dependences of resistance, indicating a three-dimensional TI state at low temperatures. Moreover, we observe a topological phase switching between the TI state and non-equilibrium Dirac semimetal state by a dc current, which is a unique functionality of a correlation-driven TI state. Our findings demonstrate that correlation-driven TIs are promising candidates not only for practical electronic devices but also as a field for discovering new topological phenomena and phases.
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Affiliation(s)
- Tetsuya Nomoto
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba, 277-8581, Japan.
- Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.
| | - Shusaku Imajo
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Hiroki Akutsu
- Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Yasuhiro Nakazawa
- Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Yoshimitsu Kohama
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
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6
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Imajo S, Matsuyama N, Nomura T, Kihara T, Nakamura S, Marcenat C, Klein T, Seyfarth G, Zhong C, Kageyama H, Kindo K, Momoi T, Kohama Y. Magnetically Hidden State on the Ground Floor of the Magnetic Devil's Staircase. Phys Rev Lett 2022; 129:147201. [PMID: 36240417 DOI: 10.1103/physrevlett.129.147201] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/20/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
We investigated the low-temperature and high-field thermodynamic and ultrasonic properties of SrCu_{2}(BO_{3})_{2}, which exhibits various plateaux in its magnetization curve above 27 T, called a magnetic Devil's staircase. The results of the present study confirm that magnetic crystallization, the first step of the staircase, occurs above 27 T as a first-order transition accompanied by a sharp singularity in heat capacity C_{p} and a kink in the elastic constant. In addition, we observe a thermodynamic anomaly at lower fields around 26 T, which has not been previously detected by any magnetic probes. At low temperatures, this magnetically hidden state has a large entropy and does not exhibit Schottky-type gapped behavior, which suggests the existence of low-energy collective excitations. Based on our observations and theoretical predictions, we propose that magnetic quadrupoles form a spin-nematic state around 26 T as a hidden state on the ground floor of the magnetic Devil's staircase.
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Affiliation(s)
- S Imajo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - N Matsuyama
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - T Nomura
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - T Kihara
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Nakamura
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - C Marcenat
- Université Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, 38000 Grenoble, France
| | - T Klein
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, F-38000 Grenoble, France
| | - G Seyfarth
- LNCMI-EMFL, CNRS, Université Grenoble Alpes, INSA-T, UPS, F-38042 Grenoble, France
| | - C Zhong
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - H Kageyama
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - K Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - T Momoi
- Condensed Matter Theory Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Y Kohama
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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7
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Miyoshi Y, Shinohara I, Ukhorskiy S, Claudepierre SG, Mitani T, Takashima T, Hori T, Santolik O, Kolmasova I, Matsuda S, Kasahara Y, Teramoto M, Katoh Y, Hikishima M, Kojima H, Kurita S, Imajo S, Higashio N, Kasahara S, Yokota S, Asamura K, Kazama Y, Wang SY, Jun CW, Kasaba Y, Kumamoto A, Tsuchiya F, Shoji M, Nakamura S, Kitahara M, Matsuoka A, Shiokawa K, Seki K, Nosé M, Takahashi K, Martinez-Calderon C, Hospodarsky G, Colpitts C, Kletzing C, Wygant J, Spence H, Baker DN, Reeves GD, Blake JB, Lanzerotti L. Collaborative Research Activities of the Arase and Van Allen Probes. Space Sci Rev 2022; 218:38. [PMID: 35757012 PMCID: PMC9213325 DOI: 10.1007/s11214-022-00885-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 03/23/2022] [Indexed: 06/15/2023]
Abstract
This paper presents the highlights of joint observations of the inner magnetosphere by the Arase spacecraft, the Van Allen Probes spacecraft, and ground-based experiments integrated into spacecraft programs. The concurrent operation of the two missions in 2017-2019 facilitated the separation of the spatial and temporal structures of dynamic phenomena occurring in the inner magnetosphere. Because the orbital inclination angle of Arase is larger than that of Van Allen Probes, Arase collected observations at higher L -shells up to L ∼ 10 . After March 2017, similar variations in plasma and waves were detected by Van Allen Probes and Arase. We describe plasma wave observations at longitudinally separated locations in space and geomagnetically-conjugate locations in space and on the ground. The results of instrument intercalibrations between the two missions are also presented. Arase continued its normal operation after the scientific operation of Van Allen Probes completed in October 2019. The combined Van Allen Probes (2012-2019) and Arase (2017-present) observations will cover a full solar cycle. This will be the first comprehensive long-term observation of the inner magnetosphere and radiation belts.
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Affiliation(s)
- Y. Miyoshi
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - I. Shinohara
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Japan
| | - S. Ukhorskiy
- Applied Physics Laboratory, The Johns Hopkins University, 11101 Johns Hopkins Rd, Laurel, MD 20723 USA
| | - S. G. Claudepierre
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, 7115 Math Sciences Bldg., Los Angeles, CA 90095 USA
| | - T. Mitani
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Japan
| | - T. Takashima
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Japan
| | - T. Hori
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - O. Santolik
- Faculty of Mathematics an Physics, Charles University, V Holesovickach 2, 18000 Prague, Czechia
- Dept. of Space Physics, Institute of Atmospheric Physics, Czech Academy of Sciences, Bocni II 1401, 14100 Prague, Czechia
| | - I. Kolmasova
- Faculty of Mathematics an Physics, Charles University, V Holesovickach 2, 18000 Prague, Czechia
- Dept. of Space Physics, Institute of Atmospheric Physics, Czech Academy of Sciences, Bocni II 1401, 14100 Prague, Czechia
| | - S. Matsuda
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192 Japan
| | - Y. Kasahara
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192 Japan
| | - M. Teramoto
- Graduate School of Engineering, Kyushu Institute of Technology, Kitakyusyu, 804-8550 Japan
| | - Y. Katoh
- Graduate School of Science, Tohoku University, Sendai, 980-8578 Japan
| | - M. Hikishima
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Japan
| | - H. Kojima
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, 611-0011 Japan
| | - S. Kurita
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, 611-0011 Japan
| | - S. Imajo
- Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
| | - N. Higashio
- Strategic Planning and Management Department, Japan Aerospace Exploration Agency, Tokyo, 101-8008 Japan
| | - S. Kasahara
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033 Japan
| | - S. Yokota
- Graduate School of Science, Osaka University, Toyonaka, 560-0043 Japan
| | - K. Asamura
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Japan
| | - Y. Kazama
- Institute of Astronomy and Astrophysics, Academia Sinica, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617 Taiwan
| | - S.-Y. Wang
- Institute of Astronomy and Astrophysics, Academia Sinica, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617 Taiwan
| | - C.-W. Jun
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - Y. Kasaba
- Graduate School of Science, Tohoku University, Sendai, 980-8578 Japan
| | - A. Kumamoto
- Graduate School of Science, Tohoku University, Sendai, 980-8578 Japan
| | - F. Tsuchiya
- Graduate School of Science, Tohoku University, Sendai, 980-8578 Japan
| | - M. Shoji
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - S. Nakamura
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
- Institute for Advanced Research, Nagoya University, Nagoya, 464-8601 Japan
| | - M. Kitahara
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
- Graduate School of Science, Tohoku University, Sendai, 980-8578 Japan
| | - A. Matsuoka
- Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
| | - K. Shiokawa
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - K. Seki
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033 Japan
| | - M. Nosé
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - K. Takahashi
- Applied Physics Laboratory, The Johns Hopkins University, 11101 Johns Hopkins Rd, Laurel, MD 20723 USA
| | - C. Martinez-Calderon
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601 Japan
| | - G. Hospodarsky
- Department of Physics and Astronomy, University of Iowa, Van Allen Hall (VAN), Iowa City, IA 52242 USA
| | - C. Colpitts
- School of Physics and Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 USA
| | - Craig Kletzing
- Department of Physics and Astronomy, University of Iowa, Van Allen Hall (VAN), Iowa City, IA 52242 USA
| | - J. Wygant
- School of Physics and Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 USA
| | - H. Spence
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, NH 03824 USA
| | - D. N. Baker
- Laboratory for Atmospheric and Space Physics, University of Colorado, 3665 Discovery Drive, 600 UCB, Boulder, CO 80303 USA
| | - G. D. Reeves
- Inteligence & Space Reserarch Division, Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM USA
| | - J. B. Blake
- The Aerospace Corporation, P.O. Box 92957, Los Angeles, CA 90009-2957 USA
| | - L. Lanzerotti
- Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 USA
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8
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Miyoshi Y, Hosokawa K, Kurita S, Oyama SI, Ogawa Y, Saito S, Shinohara I, Kero A, Turunen E, Verronen PT, Kasahara S, Yokota S, Mitani T, Takashima T, Higashio N, Kasahara Y, Matsuda S, Tsuchiya F, Kumamoto A, Matsuoka A, Hori T, Keika K, Shoji M, Teramoto M, Imajo S, Jun C, Nakamura S. Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae. Sci Rep 2021; 11:13724. [PMID: 34257336 PMCID: PMC8277844 DOI: 10.1038/s41598-021-92611-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 06/14/2021] [Indexed: 11/16/2022] Open
Abstract
Pulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.
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Affiliation(s)
- Y Miyoshi
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan.
| | - K Hosokawa
- Graduate School of Communication Engineering and Informatics, University of Electro-Communications, Chofu, 182-8585, Japan
| | - S Kurita
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, 611-0011, Japan
| | - S-I Oyama
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan.,National Institute of Polar Research, Tachikawa, 190-8518, Japan.,University of Oulu, Pentti Kaiteran katu 1, Linnanmaa, Oulu, Finland
| | - Y Ogawa
- National Institute of Polar Research, Tachikawa, 190-8518, Japan.,The Graduate University for Advanced Studies, SOKENDAI, Hayama, 240-0193, Japan.,Joint Support-Center for Data Science Research, Research Organization of Information and Systems, Tachikawa, 190-8518, Japan
| | - S Saito
- National Institute of Information and Communications Technology, Tokyo, 184-8795, Japan
| | - I Shinohara
- Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, Japan
| | - A Kero
- Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
| | - E Turunen
- Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
| | - P T Verronen
- Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland.,Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland
| | - S Kasahara
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - S Yokota
- Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan
| | - T Mitani
- Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, Japan
| | - T Takashima
- Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, Japan
| | - N Higashio
- Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, Japan
| | - Y Kasahara
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192, Japan
| | - S Matsuda
- Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, Japan
| | - F Tsuchiya
- Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - A Kumamoto
- Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - A Matsuoka
- Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - T Hori
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan
| | - K Keika
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - M Shoji
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan
| | - M Teramoto
- Graduate School of Engineering, Kyushu Institute of Technology, Fukuoka, 820-8501, Japan
| | - S Imajo
- Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - C Jun
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan
| | - S Nakamura
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan
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9
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Imajo S, Dong C, Matsuo A, Kindo K, Kohama Y. High-resolution calorimetry in pulsed magnetic fields. Rev Sci Instrum 2021; 92:043901. [PMID: 34243466 DOI: 10.1063/5.0040655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/16/2021] [Indexed: 06/13/2023]
Abstract
We have developed a new calorimeter for measuring the thermodynamic properties in pulsed magnetic fields. Instrumental design is described along with the instrument construction details, including the sensitivity of a RuO2 thermometer. Operation of the calorimeter is demonstrated by measuring the heat capacity of three samples: pure germanium, CeCu2Ge2, and κ-(BEDT-TTF)2Cu[N(CN)2]Br, in pulsed fields up to 43.5 T. Obtaining field stability is key in measuring high-resolution heat capacity under pulsed fields. We also examine the performance of the calorimeter by employing two measurement techniques: the quasi-adiabatic and dual-slope techniques. We demonstrate that the calorimeter developed in this study is capable of performing high-resolution calorimetry in pulsed magnetic fields, which opens the door to new opportunities for high-field thermodynamic studies.
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Affiliation(s)
- Shusaku Imajo
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Chao Dong
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Akira Matsuo
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Koichi Kindo
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Yoshimitsu Kohama
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
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10
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Imajo S, Akutsu H, Kurihara R, Yajima T, Kohama Y, Tokunaga M, Kindo K, Nakazawa Y. Anisotropic Fully Gapped Superconductivity Possibly Mediated by Charge Fluctuations in a Nondimeric Organic Complex. Phys Rev Lett 2020; 125:177002. [PMID: 33156658 DOI: 10.1103/physrevlett.125.177002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 06/11/2023]
Abstract
We investigate low-temperature electronic properties of the nondimeric organic superconductor β^{''}-(ET)_{4}[(H_{3}O)Ga(C_{2}O_{4})_{3}]PhNO_{2}. By examining ultrasonic properties, charge disproportionation (CD) without magnetic field dependence is detected below T_{CD}∼8 K just above the superconducting critical temperature T_{c}∼6 K. From quantum oscillations in high fields, we find variation in the Fermi surface and mass enhancement induced by the CD. Heat capacity studies elucidate that the superconducting gap function is fully gapped in the Fermi surface, but anisotropic with fourfold symmetry. We point out that the pairing mechanism of the superconductivity is possibly dominated by charge fluctuations.
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Affiliation(s)
- S Imajo
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - H Akutsu
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - R Kurihara
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - T Yajima
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Y Kohama
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - M Tokunaga
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - K Kindo
- The Institute for Solid State Physics, the University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Y Nakazawa
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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11
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Nosé M, Matsuoka A, Kumamoto A, Kasahara Y, Teramoto M, Kurita S, Goldstein J, Kistler LM, Singh S, Gololobov A, Shiokawa K, Imajo S, Oimatsu S, Yamamoto K, Obana Y, Shoji M, Tsuchiya F, Shinohara I, Miyoshi Y, Kurth WS, Kletzing CA, Smith CW, MacDowall RJ, Spence H, Reeves GD. Oxygen torus and its coincidence with EMIC wave in the deep inner magnetosphere: Van Allen Probe B and Arase observations. Earth Planets Space 2020; 72:111. [PMID: 32831576 PMCID: PMC7410109 DOI: 10.1186/s40623-020-01235-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 07/17/2020] [Indexed: 06/11/2023]
Abstract
We investigate the longitudinal structure of the oxygen torus in the inner magnetosphere for a specific event found on 12 September 2017, using simultaneous observations from the Van Allen Probe B and Arase satellites. It is found that Probe B observed a clear enhancement in the average plasma mass (M) up to 3-4 amu at L = 3.3-3.6 and magnetic local time (MLT) = 9.0 h. In the afternoon sector at MLT ~ 16.0 h, both Probe B and Arase found no clear enhancements in M. This result suggests that the oxygen torus does not extend over all MLT but is skewed toward the dawn. Since a similar result has been reported for another event of the oxygen torus in a previous study, a crescent-shaped torus or a pinched torus centered around dawn may be a general feature of the O+ density enhancement in the inner magnetosphere. We newly find that an electromagnetic ion cyclotron (EMIC) wave in the H+ band appeared coincidently with the oxygen torus. From the lower cutoff frequency of the EMIC wave, the ion composition of the oxygen torus is estimated to be 80.6% H+, 3.4% He+, and 16.0% O+. According to the linearized dispersion relation for EMIC waves, both He+ and O+ ions inhibit EMIC wave growth and the stabilizing effect is stronger for He+ than O+. Therefore, when the H+ fraction or M is constant, the denser O+ ions are naturally accompanied by the more tenuous He+ ions, resulting in a weaker stabilizing effect (i.e., larger growth rate). From the Probe B observations, we find that the growth rate becomes larger in the oxygen torus than in the adjacent regions in the plasma trough and the plasmasphere.
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Affiliation(s)
- M. Nosé
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - A. Matsuoka
- Graduate School of Science, Kyoto University, Kyoto, Japan
| | - A. Kumamoto
- Graduate School of Science, Tohoku University, Sendai, Japan
| | - Y. Kasahara
- Advanced Research Center for Space Science and Technology, Kanazawa University, Kanazawa, Japan
| | - M. Teramoto
- Department of Space Systems Engineering, Kyushu Institute of Technology, Kitakyusyu, Japan
| | - S. Kurita
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - J. Goldstein
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX USA
- University of Texas at San Antonio, San Antonio, TX USA
| | - L. M. Kistler
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH USA
| | - S. Singh
- Indian Institute of Geomagnetism, Navi Mumbai, India
| | - A. Gololobov
- North-Eastern Federal University, Yakutsk, Russia
| | - K. Shiokawa
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - S. Imajo
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - S. Oimatsu
- Graduate School of Science, Kyoto University, Kyoto, Japan
| | - K. Yamamoto
- Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Y. Obana
- Faculty of Engineering, Osaka Electro-Communication University, Neyagawa, Japan
| | - M. Shoji
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - F. Tsuchiya
- Graduate School of Science, Tohoku University, Sendai, Japan
| | - I. Shinohara
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Y. Miyoshi
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - W. S. Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA USA
| | - C. A. Kletzing
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA USA
| | - C. W. Smith
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH USA
| | - R. J. MacDowall
- Solar System Exploration Division, Goddard Space Flight Center, Greenbelt, MD USA
| | - H. Spence
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH USA
| | - G. D. Reeves
- Space Sciences and Applications Group, Los Alamos National Laboratory, Los Alamos, NM USA
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12
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Morritt AL, Lopez JR, Blundell TJ, Canadell E, Akutsu H, Nakazawa Y, Imajo S, Martin L. 2D Molecular Superconductor to Insulator Transition in the β''-(BEDT-TTF) 2[(H 2O)(NH 4) 2M(C 2O 4) 3]·18-crown-6 Series (M = Rh, Cr, Ru, Ir). Inorg Chem 2019; 58:10656-10664. [PMID: 31380643 DOI: 10.1021/acs.inorgchem.9b00292] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The series of salts β''-(BEDT-TTF)2[(H2O)(NH4)2M(C2O4)3]·18-crown-6 show ambient-pressure superconductivity when M = Cr, Rh. Evidence indicates that the previously reported Cr and Rh salts show a bulk Berezinski-Kosterlitz-Thouless superconducting transition. The isostructural ruthenium and iridium salts are reported here. The Ir salt represents the first radical-cation salt to contain a 5d tris(oxalato)metalate anion. The Ru and Ir salts do not show superconductivity but instead undergo a broad chemically induced metal to insulator transition at 155 K for ruthenium and at 100 K for iridium. The c axes of the Ru and Ir salts are much shorter than those of the Rh and Cr salts. Thus, the more stable metallic state of the Cr and Rh salts is associated with the more strongly 2D electronic systems. The different low-temperature behavior of the Ru and Ir salts, which exhibit a smaller interlayer spacing, could originate from a structural change in the anionic layer which thus can be easily transmitted to the donor layers and generate a localized state. However, another possibility is that it originates from Berezinski-Kosterlitz-Thouless effects.
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Affiliation(s)
- Alexander L Morritt
- School of Science and Technology , Nottingham Trent University , Clifton Lane , Nottingham NG11 8NS , United Kingdom
| | - Jordan R Lopez
- School of Science and Technology , Nottingham Trent University , Clifton Lane , Nottingham NG11 8NS , United Kingdom
| | - Toby J Blundell
- School of Science and Technology , Nottingham Trent University , Clifton Lane , Nottingham NG11 8NS , United Kingdom
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Campus de la UAB, 08193 Bellaterra , Spain
| | - Hiroki Akutsu
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Yasuhiro Nakazawa
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Shusaku Imajo
- Institute for Solid State Physics , University of Tokyo , Kashiwa 277-8581 , Japan
| | - Lee Martin
- School of Science and Technology , Nottingham Trent University , Clifton Lane , Nottingham NG11 8NS , United Kingdom
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13
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Martin L, Lopez JR, Akutsu H, Nakazawa Y, Imajo S. Bulk Kosterlitz-Thouless Type Molecular Superconductor β″-(BEDT-TTF) 2[(H 2O)(NH 4) 2Cr(C 2O 4) 3]·18-crown-6. Inorg Chem 2017; 56:14045-14052. [PMID: 29120611 DOI: 10.1021/acs.inorgchem.7b02171] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new molecular superconductor, β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C2O4)33-. The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β″ packing motif (layer A), layers of NH4+ and Λ-Cr(C2O4)33- (layer B), layers of (H2O)(NH4)18-crown-6 (layer C), and layers of NH4+ and Δ-Cr(C2O4)33- (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA. As a result of this packing arrangement, this is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β″). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0-4.9 and 2.5 K, respectively. The strong 2D nature of this system, the broad transition to Tzero at 1.8K, and the transition of α of V ∝ Iα from 1 to 3 on I-V curves strongly suggest that the superconducting transition is very close to a Kosterlitz-Thouless transition. The magnetic field dependence of the superconducting critical temperature parallel to the conducting plane gives an upper critical field μ0Hc2∥ > 8 T, which is over the calculated Pauli-Clogston limit for this material.
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Affiliation(s)
- Lee Martin
- School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Jordan R Lopez
- School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Hiroki Akutsu
- Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yasuhiro Nakazawa
- Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Shusaku Imajo
- Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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14
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Martin L, Morritt AL, Lopez JR, Nakazawa Y, Akutsu H, Imajo S, Ihara Y, Zhang B, Zhang Y, Guo Y. Molecular conductors from bis(ethylenedithio)tetrathiafulvalene with tris(oxalato)rhodate. Dalton Trans 2017; 46:9542-9548. [PMID: 28702555 DOI: 10.1039/c7dt00881c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article reports a family of new radical-cation salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with tris(oxalato)rhodate: three salts with the formula β''-(BEDT-TTF)4[(cation)Rh(C2O4)3]·solvent (solvent = fluorobenzene, chlorobenzene, or bromobenzene) and one with the formula pseudo-κ-(BEDT-TTF)4[(NH4)Rh(C2O4)3]·benzonitrile. We report here the syntheses, crystal structures, electrical properties and Raman spectroscopy of these new molecular conductors. The bromobenzene salt shows a decrease in resistivity below 2.5 K indicative of a superconducting transition and a Shubnikov-de Haas oscillation with a frequency of 232 T and effective mass m* of 1.27me.
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Affiliation(s)
- Lee Martin
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
| | - Alexander L Morritt
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
| | - Jordan R Lopez
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
| | - Yasuhiro Nakazawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Hiroki Akutsu
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Shusaku Imajo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Yoshihiko Ihara
- Department of Quantum and Condensed Matter Physics, School of Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Hokkaido, Japan
| | - Bin Zhang
- Organic Solid Laboratory, BNLMS, CMS & Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Yan Zhang
- Institute of Condensed Matter and Material Physics, Department of Physics, Peking University, Beijing, 100871, P. R. China
| | - Yanjun Guo
- National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
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15
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Martin L, Morritt AL, Lopez JR, Akutsu H, Nakazawa Y, Imajo S, Ihara Y. Ambient-pressure molecular superconductor with a superlattice containing layers of tris(oxalato)rhodate enantiomers and 18-crown-6. Inorg Chem 2017; 56:717-720. [PMID: 28055197 DOI: 10.1021/acs.inorgchem.6b02708] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a novel multilayered organic-inorganic hybrid material, β″-(BEDT-TTF)2[(H2O)(NH4)2Rh(C2O4)3]·18-crown-6. This is the first molecular superconductor to have a superlattice with layers of both BEDT-TTF and 18-crown-6 and also the first with the anion tris(oxalato)rhodate. This is the 2D superconductor with the widest gap between conducting layers, where only a single donor packing motif is observed (β″). The strong 2D nature of this system strongly suggests that the superconducting transition is a Kosterlitz-Thouless transition. A superconducting Tc of 2.7 K at ambient pressure was found by transport measurements and 2.5 K by magnetic susceptibility measurements.
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Affiliation(s)
- Lee Martin
- School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, U.K
| | - Alexander L Morritt
- School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, U.K
| | - Jordan R Lopez
- School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, U.K
| | - Hiroki Akutsu
- Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Yasuhiro Nakazawa
- Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Shusaku Imajo
- Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Yoshihiko Ihara
- Department of Quantum and Condensed Matter Physics, School of Science, Hokkaido University , Kita-ku, Sapporo, Hokkaido 060-0810, Japan
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16
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Imajo S, Kigawa I, Ito S, Miura S, Naito K, Yokota S, Yamashita Y, Fukuda S, Wanibuchi Y. [Lateral femoral circumflex artery for coronary artery bypass surgery in a patient receiving hemodialysis: report of a case]. Kyobu Geka 2002; 55:409-12. [PMID: 11995323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
A 59-year-old man receiving hemodialysis had a 2-vessel coronary disease. We performed double coronary artery bypass grafting with the left internal thoracic artery to the left anterior descending artery, and the composite graft of right internal thoracic artery and lateral femoral circumflex artery to the right coronary artery. Postoperative coronary angiogram showed that the LFCA bypass graft was widely patent and supplied sufficient blood to the anastomosed vessel. There was no stenosis at the anastomotic site. He had no postoperative complication. Long-term follow-up and more cases is necessary to establish the usefulness of LFCA as an arterial free graft for coronary revascularization in patients receiving hemodialysis.
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Affiliation(s)
- S Imajo
- Division of Cardiovascular Surgery, Department of Surgery, Mitsui Memorial Hospital, Tokyo, Japan
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17
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Fukami H, Imajo S, Ito A, Kakutani S, Shibata H, Sumida M, Tanaka T, Niwata S, Saitoh M, Kiso Y, Miyazaki M, Okunishi H, Urata H, Arakawa K. Substituted 3-phenylsulfonylquinazoline-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase. Drug Des Discov 2001; 17:69-84. [PMID: 10928450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
A series of 3-phenylsulfonylquinazoline-2,4-dione derivatives have been synthesized and evaluated for their ability to inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The phenyl moiety of quinazoline participates in a hydrophobic interaction where an optimum size is required. In this moiety, 7-chloroquinazoline is the best moiety for inhibiting chymase, chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrophobic electron-withdrawing groups at the 4-position potentiated the activity. Anthranil moiety also enhanced the activity. Pyridylmethyl and N-pyridylacetamide at the 1-position gave an IC50 in the order of 10(-8)M. Molecular modeling studies on the interaction of 7-chloro-3-(4-chlorophenylsulfonyl) quinazoline-2,4(1H, 3H)-dione (4) with the active site of human heart chymase suggested that the phenyl moiety of quinazoline interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, the moiety at the 1-position locates in the S2-S3 subsites and the 4-carbonyl and 3-sulfonyl group interact with the oxyanion hole and the His57 side-chain of chymase, respectively.
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Affiliation(s)
- H Fukami
- Institute for Biomedical Research, Suntory Ltd., Osaka, Japan
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18
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Annoura H, Nakanishi K, Toba T, Takemoto N, Imajo S, Miyajima A, Tamura-Horikawa Y, Tamura S. Discovery of (2S)-1-(4-amino-2,3,5- trimethylphenoxy)-3-[4-[4-(4- fluorobenzyl)phenyl]-1-piperazinyl]-2-propanol dimethanesulfonate (SUN N8075): a dual Na(+) and Ca(2+) channel blocker with antioxidant activity. J Med Chem 2000; 43:3372-6. [PMID: 10978184 DOI: 10.1021/jm000143w] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- H Annoura
- Suntory Biomedical Research Limited, 1-1-1, Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618-8503, Japan.
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19
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Ohtsubo K, Imajo S, Ishiguro M, Nakatani T, Oka S, Kawasaki T. Studies on the structure-function relationship of the HNK-1 associated glucuronyltransferase, GlcAT-P, by computer modeling and site-directed mutagenesis. J Biochem 2000; 128:283-91. [PMID: 10920264 DOI: 10.1093/oxfordjournals.jbchem.a022751] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
All members of a glucuronyltransferase (GlcAT) gene family cloned to date contain four conserved regions (modules I-IV), which are widely located in the catalytic domain. In order to understand the biological significance of these modules, we investigated the structure-function relationship of GlcAT-P by means of the combination of site-directed mutagenesis and computer aided three-dimensional modeling. The wild-type and mutant GlcAT-Ps were expressed in Escherichia coli as glutathione-S-transferase (GST)-fused soluble proteins. Most of the mutants in which a polar amino acid within the modules was replaced with alanine lost their transferase activity almost completely, while all of the mutants in which the replacement was outside these modules retained the original catalytic activity. A three-dimensional (3-D) model of GlcAT-P was constructed by computer simulation with the three-dimensional structure of adenylate kinase (1AKE) as a template. This model predicted that the large catalytic domain of GlcAT-P forms a globular shape with a Rossmann-fold motif consisting of five alpha-helix and beta-sheet repeats. The putative catalytic pocket consisting mainly of modules I-III is surrounded by a cluster of polar amino acids, which are essential for the transferase activity and also for the binding to the acceptor substrate (essential amino acids), asialo-orosomucoid. There is the second cluster of essential amino acids almost on the opposite surface of the molecule, in which an aspartic acid repeat (DDD) is located. The biological significance of the second cluster is currently not clear but it may be associated with the interaction of the enzyme with modulation molecules, manganese and membrane phospholipids.
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Affiliation(s)
- K Ohtsubo
- Department of Biological Chemistry and CREST (Core Research for Educational Science and Technology) Project, Japan Science and Technology Corporation, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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20
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Ishiguro M, Imajo S. The role of water molecules in the deacylation of acylated structures of class A beta-lactamase. Drug Des Discov 1999; 16:131-43. [PMID: 10533809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Molecular dynamics simulation of the penicillin- and penem-acylated enzymes reveals that the conformational flexibility of the acyl moieties in the binding cleft and the conformational change of the acyl moieties are crucial for deacylation. The water molecule adjacent to the Glu 166 residue is not the nucleophile for deacylation, but construction of a model of the oxyanion tetrahedral intermediate suggested a plausible role of the water molecule as a proton donor for the oxyanion to facilitate the deacylation.
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Affiliation(s)
- M Ishiguro
- Suntory Institute for Bioorganic Research and for Biomedical Research, Shimamoto, Osaka, Japan.
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21
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Niwata S, Fukami H, Sumida M, Ito A, Kakutani S, Saitoh M, Suzuki K, Imoto M, Shibata H, Imajo S, Kiso Y, Tanaka T, Nakazato H, Ishihara T, Takai S, Yamamoto D, Shiota N, Miyazaki M, Okunishi H, Kinoshita A, Urata H, Arakawa K. Substituted 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase. J Med Chem 1997; 40:2156-63. [PMID: 9216834 DOI: 10.1021/jm960793t] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A series of 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives have been synthesized and evaluated for their ability to selectively inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The 1-phenyl moiety participates in a hydrophobic interaction where an optimum size is required. At this position, 3,4-dimethylphenyl is the best moiety for inhibiting chymase and showed high selectivity compared with chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrogen-bond acceptors such as nitrile and methoxycarbonyl enhances its activity. Molecular-modeling studies on the interaction of 3-[(4-chlorophenyl)sulfonyl]-1-(4-chlorophenyl)-imidazolidine-2,4-dione (29) with the active site of human heart chymase suggested that the 1-phenyl moiety interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, and the 4-carbonyl of the imidazolidine ring and sulfonyl group interact with the oxyanion hole and the His-45 side chain of chymase, respectively. The complex model is consistent with the structure-activity relationships.
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Affiliation(s)
- S Niwata
- Institute for Biomedical Research, Suntory Ltd., Osaka, Japan
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22
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Ishiguro M, Tanaka R, Namikawa K, Nasu T, Inoue H, Nakatsuka T, Oyama Y, Imajo S. 5,6-Cis-penems: broad-spectrum anti-methicillin-resistant Staphylococcus aureus beta-lactam antibiotics. J Med Chem 1997; 40:2126-32. [PMID: 9216830 DOI: 10.1021/jm9703348] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
5,6-cis-Penem derivatives have been synthesized and evaluated as anti-MRSA antibiotics. The cis-penems 5 and 6 showed potent activities against not only MRSA but also a wide variety of bacteria including beta-lactamase-producing microorganisms. These compounds were designed to have high affinity to the penicillin-binding protein 2a of MRSA and to form stable acyl intermediates with beta-lactamases by blocking the deacylating water molecule.
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Affiliation(s)
- M Ishiguro
- Suntory Institute for Bioorganic Research, Institute for Biomedical Research, Osaka, Japan
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23
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Tanaka R, Oyama Y, Imajo S, Matsuki S, Ishiguro M. Structure-activity relationships of penem antibiotics: crystallographic structures and implications for their antimicrobial activities. Bioorg Med Chem 1997; 5:1389-99. [PMID: 9377099 DOI: 10.1016/s0968-0896(97)00073-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Twelve closely related crystal structures of the penem derivatives revealed a characteristic short contact of the oxygen atom in the C2 side-chains with the S1 atom. The side-chain conformations of the crystal structures showed a good correlation with the antimicrobial activity. In particular, the penems which show high antimicrobial activity have similar torsion angles for S1-C2-C1'-C2', suggesting that the disposition of the C2' atom would be important for binding to penicillin-interacting enzymes. Two conformations of the C6 hydroxyethyl group were observed in the crystal structures. Of those two, the conformation with a larger torsion angle (delta = 179.2 degrees) is deduced to be the enzyme-bound conformation in the Michaelis complex.
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Affiliation(s)
- R Tanaka
- Suntory Ltd, Institute for Biomedical Research, Shimamoto, Osaka, Japan
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24
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Murai S, Imajo S, Inumaru H, Takahashi K, Hattori K. Adsorption and Recovery of Ionic Surfactants by beta-Cyclodextrin Polymer. J Colloid Interface Sci 1997; 190:488-90. [PMID: 9241195 DOI: 10.1006/jcis.1997.4873] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The adsorption and recovery of ionic surfactants, such as dodecylbenzenesulfonic acid (DBS) and benzalkonium chloride (BKC), from an aqueous solution were studied using the beta-cyclodextrin polymer (beta-CDP). BKC always demonstrated a higher adsorption efficiency than DBS in batch tests, isotherms, and column tests. The adsorption characteristics of the surfactants seemed to be caused by inclusion into beta-CD, and they were easily determined using the Langmuir adsorption isotherm. Furthermore, the surfactants adsorbed by beta-CDP were easily released by shaking it with a mixture of water and methanol. Recovery efficiency was dependent on the mixture ratio of the solvent, and regenerated beta-CDP was reusable as an adsorbent.
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Affiliation(s)
- S Murai
- Kanagawa Industrial Technology Research Institute, Shimoimaizumi 705, Ebina, Kanagawa, 243-04, Japan
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25
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Abstract
Comparison of the hydrogen-bond networks at the active site in the crystallographic structures reported for class A beta-lactamases revealed an importance of a switch of the hydrogen-bond network for the catalytic process. Taking account of the conformational mobility of the Lys73 residue, we have constructed putative complex models for beta-lactam antibiotics and the enzymes in the multistep hydrolysis which consists of a Michaelis complex, an acyl-enzyme, and a tetrahedral oxyanion for deacylation. In the acylation, the C3 carboxylate of penicillin derivatives would participate in activation of the Ser130 hydroxyl group and then the oxyanion of the Ser130 residue would deprotonate the ammonium group of the Lys73 residue which will act as a general base for activation of the Ser70 residue. In the deacylation, the deacylating water molecule would be accommodated during a conformational change of the acyl moiety without a structural change of the active-site residues and the unprotonated N4 atom of the penicillins would act as a general base to activate the water molecule. This catalytic process provided a new account for the stability of the acyl-enzyme complexes. This substrate-assisted mechanism would also be extended to a hydrolytic mechanism of class C enzymes.
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Affiliation(s)
- M Ishiguro
- Suntory Ltd., Institute for Biomedical Research, Osaka, Japan
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26
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Abstract
An experiment was conducted to examine which was crucial for the reactance effect on attitude change: discrepancy, initial position or prerequisite conditions for reactance arousal. Initial receiver attitudes were one of the five levels: moderate or extreme agreement (the least discrepancy), slight agreement, neutral, slight disagreement, and moderate or extreme disagreement (the most discrepancy), and threat to attitudinal freedom was manipulated. Prerequisite conditions for reactance arousal were also measured. Threat manipulation significantly reduced opinion change only among receivers at neutral or moderate/extreme disagreement position. In addition, examination of prerequisites showed that compliance in high threat condition was significantly less for receivers who had been uncertain about their own initial position and had perceived the issue important (freedom-of-choice group) and those who had perceived the attacked position as both possible and important (freedom-of-position group). Theoretical and practical significance of prerequisites for reactance arousal is discussed.
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Affiliation(s)
- S Imajo
- Department of Human Behavioral Science, Hokkaido University of Education, Hakodate
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27
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Ishii Y, Ohno A, Taguchi H, Imajo S, Ishiguro M, Matsuzawa H. Cloning and sequence of the gene encoding a cefotaxime-hydrolyzing class A beta-lactamase isolated from Escherichia coli. Antimicrob Agents Chemother 1995; 39:2269-75. [PMID: 8619581 PMCID: PMC162928 DOI: 10.1128/aac.39.10.2269] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Escherichia coli TUH12191, which is resistant to piperacillin, cefazolin, cefotiam, ceftizoxime, cefuzonam, and aztreonam but is susceptible to cefoxitin, latamoxef, flomoxef, and imipenem, was isolated from the urine of a patient treated with beta-lactam antibiotics. The beta-lactamase (Toho-1) purified from the bacteria had a pI of 7.8, had a molecular weight of about 29,000, and hydrolyzed beta-lactam antibiotics such as penicillin G, ampicillin, oxacillin, carbenicillin, piperacillin, cephalothin, cefoxitin, cefotaxime, ceftazidime, and aztreonam. Toho-1 was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid and tazobactam. Resistance to beta-lactams, streptomycin, spectinomycin, sulfamethoxazole, and trimethoprim was transferred by conjugational transfer from E. coli TUH12191 to E. coli ML4903, and the transferred plasmid was about 58 kbp, belonging to incompatibility group M. The cefotaxime resistance gene for Toho-1 was subcloned from the 58-kbp plasmid by transformation of E. coli MV1184. The sequence of the gene for Toho-1 was determined, and the open reading frame of the gene consisted of 873 or 876 bases (initial sequence, ATGATG). The nucleotide sequence of the gene (DDBJ accession number D37830) was found to be about 73% homologous to the sequence of the gene encoding a class A beta-lactamase produced by Klebsiella oxytoca E23004. According to the amino acid sequence deduced from the DNA sequence, the precursor consisted of 290 or 291 amino acid residues, which contained amino acid motifs common to class A beta-lactamases (70SXXK, 130SDN, and 234KTG). Toho-1 was about 83% homologous to the beta-lactamase mediated by the chromosome of K. oxytoca D488 and the beta-lactamase mediated by the plasmid of E. coli MEN-1. Therefore, the newly isolated beta-lactamase Toho-1 produced by E. coli TUH12191 is similar to beta-lactamases produced by K. oxytoca D488, K. oxytoca E23004, and E. coli MEN-1 rather than to mutants of TEM or SHV enzymes. Toho-1 has shown the highest degree of similarity to K. oxytoca class A beta-lactamase. Detailed comparison of Toho-1 with other beta-lactamases implied that replacement of Asn-276 by Arg with the concomitant substitution of Thr for Arg-244 is an important mutation in the extension of the substrate specificity.
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Affiliation(s)
- Y Ishii
- Department of Microbiology, Toho University School of Medicine, Tokyo, Japan
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28
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Abstract
A structure of neocarzinostatin, an antitumor chromoprotein antibiotic, has been built using X-ray crystallographic data and NMR data, particularly NOE data observed between the apoprotein and the chromophore. Chemical shift changes of protons of the chromophore upon binding to the apoprotein indicated that the aromatic plane of Phe52 has the conformation almost perpendicular to the C-2-C-3 triple bond of the core of the chromophore while Phe78 takes multiple conformations in solution although one of the stable conformations has been assigned for Phe78 in a crystal structure.
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Affiliation(s)
- S Imajo
- Suntory Institute for Biomedical Research, Osaka, Japan
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29
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Imajo S, Ishiguro M, Ishiguro K, Murashima T, Isoi K, Tanahashi H, Nishino H. The specific inhibition of crystal growth of monohydrogen potassium L-tartrate by d-catechin. Bioorg Med Chem 1994; 2:1021-7. [PMID: 7773619 DOI: 10.1016/s0968-0896(00)82052-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Crystal growth of monohydrogen potassium L-tartrate in an ethanolic aqueous solution was specifically inhibited by d-catechin, but not by either its epimeric isomer at C3, l-epicatechin or by gallic acid and caffeic acid. 3D-Structure similarity search of d-catechin with two molecules of the tartrate and docking study of d-catechin with the crystal model of the tartrate suggested that d-catechin mimics a structure consisting of the two tartrate molecules in the inhibition. Differences in the conformation of the catechol moieties of d-catechin and l-epicatechin may explain the distinct inhibitory effects of the epimeric isomers.
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Affiliation(s)
- S Imajo
- Institute for Biomedical Research, Suntory Ltd, Osaka, Japan
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30
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31
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Nukaga M, Tanimoto K, Tsukamoto K, Imajo S, Ishiguro M, Sawai T. A survey of a functional amino acid of class C beta-lactamase corresponding to Glu166 of class A beta-lactamases. FEBS Lett 1993; 332:93-8. [PMID: 8104827 DOI: 10.1016/0014-5793(93)80491-c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The class C beta-lactamase of Citrobacter freundii GN346 is a typical cephalosporinase comprising 361 amino acids. The aspartic acid at position 217 and glutamic acid at position 219 in this beta-lactamase were, respectively, previously shown not to be the counterpart of Glu166 (ABL166) in class A beta-lactamases, even though sequence alignment of class A and C enzymes strongly suggested this possibility [(1990) FEBS Lett. 264, 211-214; (1990) J. Bacteriol. 172, 4348-4351]. We tried again to assign candidates for the counterpart of Glu166 through sequence alignment based on other criteria, the glutamic acids at positions 195 and 205 in the class C beta-lactamase being selected. To investigate this possibility, these two glutamic acids were changed to glutamine, lysine or alanine, respectively. All the mutant enzymes showed more than 50% of the activity of the wild-type enzyme, indicating that the possibility was ruled out. These results strongly suggested the possibility that the class C beta-lactamase lacks a functional acidic residue corresponding to Glu166 in class A enzymes.
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Affiliation(s)
- M Nukaga
- Division of Microbial Chemistry, Faculty of Pharmaceutical Sciences, Chiba University, Japan
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32
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Tsuru D, Imajo S, Morikawa S, Yoshimoto T, Ishiguro M. Zinc protease of Bacillus subtilis var. amylosacchariticus: construction of a three-dimensional model and comparison with thermolysin. J Biochem 1993; 113:101-5. [PMID: 8454566 DOI: 10.1093/oxfordjournals.jbchem.a123991] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The active site structure of the Zn-containing neutral protease from Bacillus subtilis var. amylosacchariticus (BANP) was predicted by computer-aided modeling on the basis of the three-dimensional structure of thermolysin (TLN). As expected from the high homology in amino acid sequence of the two enzymes, the overall folding of BANP was very similar to that of TLN. Glu144, Tyr158, and His228 of BANP were located near the active site Zn ion, to which three amino acid residues, His143, His147, and Glu167, were coordinated. This model is supported by the previous results that chemical modifications of Tyr158 and photooxidation of His228 of BANP markedly affect the proteolytic activity of the enzyme. Interestingly, BANP was found to be significantly less sensitive to metalloprotease inhibitors such as phosphoramidon and talopeptin. From a comparison of the enzyme-inhibitor complex models between BANP and thermolysin, it is suggested that replacement of Thr129 in TLN by Phe130 in BANP is related to difference in inhibitor sensitivity between BANP and TLN.
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Affiliation(s)
- D Tsuru
- School of Pharmaceutical Sciences, Nagasaki University
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33
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Ishiguro M, Imajo S, Hirama M. Modeling study of the structure of the macromolecular antitumor antibiotic neocarzinostatin. Origin of the stabilization of the chromophore. J Med Chem 1991; 34:2366-73. [PMID: 1831507 DOI: 10.1021/jm00112a008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A three-dimensional structure of the apoprotein of neocarzinostatin (NCS) was built by using the actinoxanthin (AXN) crystal structure as template, and the subsequent favored-site search for the binding of the fragments of the chromophore of NCS at the binding cleft led to a reasonable complex structure of apo-NCS and the chromophore, after refinement of the molecular mechanics program AMBER. The refined three-dimensional structure model of NCS shows the "Y"-shaped cleft of the binding site in which the bicyclic epoxy dienediyne part 4 and its substituents, the naphthoate 3, the amino sugar 2, and cyclic carbonate 1 moieties are nicely fitted. Contacts of the chromophore with the specific amino acid residues in the cleft indicate their contribution to the specific and high affinity binding through ionic interaction, hydrogen bonding, aromatic stacking, and van der Waals contact. Stabilization of the labile chromophore is likely due to the steric hindrance toward the reactive sites such as the C12 position as well as the epoxide, and, more interestingly, the stabilization interaction between the disulfide group (Cys37 and Cys47) and the acetylenic bond is also suggested.
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Affiliation(s)
- M Ishiguro
- Suntory Institute for Biomedical Research, Osaka, Japan
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34
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Ishida N, Aoyama Y, Hatanaka R, Oyama Y, Imajo S, Ishiguro M, Oshima T, Nakazato H, Noguchi T, Maitra US. A single amino acid substitution converts cytochrome P450(14DM) to an inactive form, cytochrome P450SG1: complete primary structures deduced from cloned DNAS. Biochem Biophys Res Commun 1988; 155:317-23. [PMID: 3046615 DOI: 10.1016/s0006-291x(88)81087-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Genes for lanosterol 14-demethylase, cytochrome P450(14DM), and a mutated inactive cytochrome P450SG1 were cloned from S. cerevisiae strains D587 and SG1, respectively. A single nucleotide change resulting in substitution of Asp for Gly-310 of cytochrome P450(14DM) was found to have occurred in cytochrome P450SG1. In this protein the 6th ligand to heme iron is a histidine residue instead of a water molecule, which may be the ligand for the active cytochrome P450(14DM). Molecular models of the active sites of the cytochrome P450(14DM) and cytochrome P450SG1 were built by computer modeling on the basis of the known structure of that of cytochrome P450CAM whose crystallographic data are available. The mechanisms which may cause a histidine residue to gain access to the heme iron are discussed.
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Affiliation(s)
- N Ishida
- Suntory Institute for Biomedical Research, Osaka, Japan
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35
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Oikawa S, Imajo S, Noguchi T, Kosaki G, Nakazato H. The carcinoembryonic antigen (CEA) contains multiple immunoglobulin-like domains. Biochem Biophys Res Commun 1987; 144:634-42. [PMID: 3579935 DOI: 10.1016/s0006-291x(87)80013-x] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The amino acid sequences of human carcinoembryonic antigen deduced from the cDNA sequences have been analysed. This antigen contains seven extracellular domains (previously recognized three highly repetitive domains are further divided into A and B subdomains each) which are strikingly homologous to each other and to immunoglobulin variable regions, poly-Ig receptor and Thy 1.1. The N-terminal domain lacks immunoglobulin-like fold but the other six domains have, suggesting that the CEA belongs to immunoglobulin superfamily.
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36
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Sassa S, Sugita O, Kappas A, Ohnuma N, Imajo S, Okumura T, Noguchi T. Chloro-substituent sites and probability of co-planarity in polychlorinated biphenyls in determining uroporphyrin formation in cultured liver cells. Biochem J 1986; 240:622-3. [PMID: 3101676 PMCID: PMC1147462 DOI: 10.1042/bj2400622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Sassa S, Sugita O, Ohnuma N, Imajo S, Okumura T, Noguchi T, Kappas A. Studies of the influence of chloro-substituent sites and conformational energy in polychlorinated biphenyls on uroporphyrin formation in chick-embryo liver cell cultures. Biochem J 1986; 235:291-6. [PMID: 3091004 PMCID: PMC1146680 DOI: 10.1042/bj2350291] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Treatment of cultured chick-embryo liver cells with polychlorinated biphenyls (PCB) results in decreased uroporphyrinogen decarboxylase activity and increased uroporphyrin accumulation. In the present study we examined the effect of the chloro- or bromo-substituent sites in biphenyls (BP) on uroporphyrin accumulation in cultured hepatocytes and the three-dimensional structure of these congeners determined by molecular orbital calculations using a MNDO ('modified neglect of diatomic overlap') method. Among 20 congeners examined, those which were effective in stimulating porphyrin accumulation contained at least two Cl or Br atoms at the lateral adjacent positions in each phenyl ring, e.g. 3,4,3',4'-tetrachloro-, 2,4,3',4'-tetrachloro-, 3,4,5,3',4',5'-hexachloro- and 3,4,5,3',4',5'-hexabromobiphenyl, whereas those which contained less than two halogen atoms or more than three halogen atoms in each phenyl ring or those which contained halogen atoms at 2,2'-positions were not effective. On the basis of the conformational energy (delta E, difference from the most stable conformational energy), which is calculated as a function of the dihedral angle (theta) between the two phenyl rings, biphenyl congeners can be classified into four groups with different conformations. The conformation of active PCB was relatively flexible, whereas inactive species had a rigidly angulated conformation. Furthermore, the calculated probability of the conformation distribution for each congener indicated that the probability of co-planarity was higher for active biphenyls than for inactive congeners. These structural characteristics suggest the significance of both the chloro-substituent sites and the conformational energy reflecting the phenyl-ring twist angles in determining the inhibitory effect of PCB on uroporphyrinogen decarboxylase activity.
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Nakai H, Shiro M, Imajo S, Kuritani H, Shingu K. Structure of (9S,P)-(+)-7,9-di-tert-butyl-9H-naphtho[1',2':3,4]cylopenta[1,2-c]phenanthrene. Acta Crystallogr Sect B 1982. [DOI: 10.1107/s056774088200973x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kobayashi H, Yuyama A, Imajo S, Matsusaka N. Effects of acute and chronic administration of DDVP (dichlorvos) on distribution of brain acetylcholine in rats. J Toxicol Sci 1980; 5:311-9. [PMID: 7218377 DOI: 10.2131/jts.5.311] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
DDVP (dichlorvos), an irreversible cholinesterase (ChE) inhibitor, was administered acutely and chronically to rats in order to investigate effects on the distribution of brain acetylcholine (ACh). In acutely treated animals (4 mg/kg, singly), cholinergic signs were evident and accompanied with a 100, 146, 113, and 61 per cent increase in total, free, labile-bound and stable-bound ACh content of the brain, respectively, and a 66 per cent decrease in acetylcholinesterase (AChE) activity 20 min after injection. In no animals treated chronically with a low dose (0.2 mg/kg/day for 9 or 90 days, or 1 mg/kg/day for 9 or 30 days), any overt sign was shown during the experimental period, and the stable-bound ACh content of the brain was not altered. In the group given 0.2 mg/kg for 90 days and that given 1.0 mg/kg for 9 or 30 days, free ACh content increased slightly but significantly, and AChE activity decreased to 58 per cent. Total ACh content and labile-bound ACh content increased only in a group given 1 mg/kg of DDVP for 30 days. These results suggest that acute, as well as chronic, exposure to organophosphate may induce alteration in mobilization and storage of ACh in the central cholinergic nerves.
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