1
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Lee MC, Sirica N, Teitelbaum SW, Maznev A, Pezeril T, Tutchton R, Krapivin V, de la Pena GA, Huang Y, Zhao LX, Chen GF, Xu B, Yang R, Shi J, Zhu JX, Yarotski DA, Qiu XG, Nelson KA, Trigo M, Reis DA, Prasankumar RP. Direct Observation of Coherent Longitudinal and Shear Acoustic Phonons in TaAs Using Ultrafast X-Ray Diffraction. Phys Rev Lett 2022; 128:155301. [PMID: 35499894 DOI: 10.1103/physrevlett.128.155301] [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: 11/13/2020] [Revised: 01/19/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Using femtosecond time-resolved x-ray diffraction, we investigated optically excited coherent acoustic phonons in the Weyl semimetal TaAs. The low symmetry of the (112) surface probed in our experiment enables the simultaneous excitation of longitudinal and shear acoustic modes, whose dispersion closely matches our simulations. We observed an asymmetry in the spectral line shape of the longitudinal mode that is notably absent from the shear mode, suggesting a time-dependent frequency chirp that is likely driven by photoinduced carrier diffusion. We argue on the basis of symmetry that these acoustic deformations can transiently alter the electronic structure near the Weyl points and support this with model calculations. Our study underscores the benefit of using off-axis crystal orientations when optically exciting acoustic deformations in topological semimetals, allowing one to transiently change their crystal and electronic structures.
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Affiliation(s)
- Min-Cheol Lee
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - N Sirica
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S W Teitelbaum
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - A Maznev
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
- Institute for Soldier Nanotechnology, Massachusetts Institute of Technology, 500 Technology Square, NE47-598, Cambridge, Massachusetts, 02139, USA
| | - T Pezeril
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
- Institut de Physique de Rennes, Université de Rennes 1, UMR CNRS 6251, 35000 Rennes, France
| | - R Tutchton
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - V Krapivin
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - G A de la Pena
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Y Huang
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - L X Zhao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - G F Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - B Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - R Yang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J Shi
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - J-X Zhu
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - D A Yarotski
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - X G Qiu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - K A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
- Institute for Soldier Nanotechnology, Massachusetts Institute of Technology, 500 Technology Square, NE47-598, Cambridge, Massachusetts, 02139, USA
| | - M Trigo
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - D A Reis
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Department of Photon Science, Stanford University, Stanford, California 94305, USA
| | - R P Prasankumar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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2
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Sirica N, Orth PP, Scheurer MS, Dai YM, Lee MC, Padmanabhan P, Mix LT, Teitelbaum SW, Trigo M, Zhao LX, Chen GF, Xu B, Yang R, Shen B, Hu C, Lee CC, Lin H, Cochran TA, Trugman SA, Zhu JX, Hasan MZ, Ni N, Qiu XG, Taylor AJ, Yarotski DA, Prasankumar RP. Photocurrent-driven transient symmetry breaking in the Weyl semimetal TaAs. Nat Mater 2022; 21:62-66. [PMID: 34750539 DOI: 10.1038/s41563-021-01126-9] [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] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Symmetry plays a central role in conventional and topological phases of matter, making the ability to optically drive symmetry changes a critical step in developing future technologies that rely on such control. Topological materials, like topological semimetals, are particularly sensitive to a breaking or restoring of time-reversal and crystalline symmetries, which affect both bulk and surface electronic states. While previous studies have focused on controlling symmetry via coupling to the crystal lattice, we demonstrate here an all-electronic mechanism based on photocurrent generation. Using second harmonic generation spectroscopy as a sensitive probe of symmetry changes, we observe an ultrafast breaking of time-reversal and spatial symmetries following femtosecond optical excitation in the prototypical type-I Weyl semimetal TaAs. Our results show that optically driven photocurrents can be tailored to explicitly break electronic symmetry in a generic fashion, opening up the possibility of driving phase transitions between symmetry-protected states on ultrafast timescales.
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Affiliation(s)
- N Sirica
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - P P Orth
- Ames Laboratory, Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, USA
| | - M S Scheurer
- Institute for Theoretical Physics, University of Innsbruck, Innsbruck, Austria
| | - Y M Dai
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
- Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China
| | - M-C Lee
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - P Padmanabhan
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - L T Mix
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - S W Teitelbaum
- Department of Physics, Arizona State Univeristy, Tempe, AZ, USA
- Beus CXFEL Labs, Biodesign Institute, Arizona State Univeristy, Tempe, AZ, USA
| | - M Trigo
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - L X Zhao
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - G F Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - B Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - R Yang
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - B Shen
- Department of Physics and Astronomy, University of California, Los Angeles, CA, USA
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Guangzhou, China
| | - C Hu
- Department of Physics and Astronomy, University of California, Los Angeles, CA, USA
| | - C-C Lee
- Department of Physics, Tamkang University, New Taipei, Taiwan
| | - H Lin
- Institute of Physics, Academia Sinica, Taipei, Taiwan
| | - T A Cochran
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, USA
| | - S A Trugman
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - J-X Zhu
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - M Z Hasan
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - N Ni
- Department of Physics and Astronomy, University of California, Los Angeles, CA, USA
| | - X G Qiu
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - A J Taylor
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - D A Yarotski
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - R P Prasankumar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA.
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3
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Chen X, Liu J, Li P, Wang JM, Zhao LX, Han XW, Chen Y, Yu HW, Ma GL. [The application of artificial intelligence on the classification of benign and malignant breast tumors based on dynamic enhanced MR images]. Zhonghua Yi Xue Za Zhi 2021; 101:3029-3032. [PMID: 34638196 DOI: 10.3760/cma.j.cn112137-20210128-00269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This retrospective analysis was conducted on clinical obtained DCE-MR images of 198 patients, age from 21 to 79 years(45.5±13.7). The CBAM-ResNet model was developed to perform the classification automatically at the image-level based on deep learning method using the pathological examination as the reference standard,then the classification result of each individual patient was obtained by ensemble learning. The proposed method can have an accuracy of 82.69% for correctly distinguishing between benign and malignant breast tumors at the slice-level based on CBAM-ResNet model and with a sensitivity of 85.67%.. After the voting mechanism is applied, the classification accuracy can reach up to 88.24% at the patient-level with a sensitivity of 87.50%. Our experimental results demonstrated the proposed approach have a high classification accuracy.
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Affiliation(s)
- X Chen
- School of Biomedical Engineering, University of Science and Technology of China, Hefei 230000, China
| | - J Liu
- Department of Radiology, China-Japan Friendship Hospital, Beijing 100029, China
| | - P Li
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science, Suzhou 215000, China
| | - J M Wang
- School of Biomedical Engineering, University of Science and Technology of China, Hefei 230000, China
| | - L X Zhao
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science, Suzhou 215000, China
| | - X W Han
- Department of Radiology, China-Japan Friendship Hospital, Beijing 100029, China
| | - Y Chen
- Department of Radiology, China-Japan Friendship Hospital, Beijing 100029, China
| | - H W Yu
- Department of Radiology, China-Japan Friendship Hospital, Beijing 100029, China
| | - G L Ma
- Department of Radiology, China-Japan Friendship Hospital, Beijing 100029, China
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4
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Sirica N, Tobey RI, Zhao LX, Chen GF, Xu B, Yang R, Shen B, Yarotski DA, Bowlan P, Trugman SA, Zhu JX, Dai YM, Azad AK, Ni N, Qiu XG, Taylor AJ, Prasankumar RP. Tracking Ultrafast Photocurrents in the Weyl Semimetal TaAs Using THz Emission Spectroscopy. Phys Rev Lett 2019; 122:197401. [PMID: 31144919 DOI: 10.1103/physrevlett.122.197401] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 02/05/2019] [Indexed: 06/09/2023]
Abstract
We investigate polarization-dependent ultrafast photocurrents in the Weyl semimetal TaAs using terahertz (THz) emission spectroscopy. Our results reveal that highly directional, transient photocurrents are generated along the noncentrosymmetric c axis regardless of incident light polarization, while helicity-dependent photocurrents are excited within the ab plane. This is consistent with earlier static photocurrent experiments, and demonstrates on the basis of both the physical constraints imposed by symmetry and the temporal dynamics intrinsic to current generation and decay that optically induced photocurrents in TaAs are inherent to the underlying crystal symmetry of the transition metal monopnictide family of Weyl semimetals.
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Affiliation(s)
- N Sirica
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R I Tobey
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Zernike Institute for Advanced Materials, University of Groningen, Groningen 9747AG, Netherlands
| | - L X Zhao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - G F Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - B Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - R Yang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - B Shen
- Department of Physics and Astronomy and California NanoSystems Institute, University of California Los Angeles, Los Angeles, California 90095, USA
| | - D A Yarotski
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P Bowlan
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S A Trugman
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J-X Zhu
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Y M Dai
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- School of Physics, Nanjing University, Nanjing 210093, China
| | - A K Azad
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - N Ni
- Department of Physics and Astronomy and California NanoSystems Institute, University of California Los Angeles, Los Angeles, California 90095, USA
| | - X G Qiu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - A J Taylor
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R P Prasankumar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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5
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Xu B, Zhao LX, Marsik P, Sheveleva E, Lyzwa F, Dai YM, Chen GF, Qiu XG, Bernhard C. Temperature-Driven Topological Phase Transition and Intermediate Dirac Semimetal Phase in ZrTe_{5}. Phys Rev Lett 2018; 121:187401. [PMID: 30444418 DOI: 10.1103/physrevlett.121.187401] [Citation(s) in RCA: 8] [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: 05/25/2018] [Indexed: 06/09/2023]
Abstract
We present an infrared spectroscopy study of ZrTe_{5}, which confirms a recent theoretical proposal that this material exhibits a temperature-driven topological quantum phase transition from a weak to a strong topological insulating state with an intermediate Dirac semimetal state around T_{p}≃138 K. Our study details the temperature evolution of the energy gap in the bulk electronic structure. We found that the energy gap closes around T_{p}, where the optical response exhibits characteristic signatures of a Dirac semimetal state, i.e., a linear frequency-dependent optical conductivity extrapolating to the origin (after subtracting a weak Drude response). This finding allows us to reconcile previous diverging reports about the topological nature of ZrTe_{5} in terms of a variation of T_{p} that depends on the crystal growth condition.
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Affiliation(s)
- B Xu
- Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - L X Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - P Marsik
- Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - E Sheveleva
- Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - F Lyzwa
- Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - Y M Dai
- Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - G F Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - X G Qiu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - C Bernhard
- Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
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6
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Xu B, Dai YM, Zhao LX, Wang K, Yang R, Zhang W, Liu JY, Xiao H, Chen GF, Trugman SA, Zhu JX, Taylor AJ, Yarotski DA, Prasankumar RP, Qiu XG. Temperature-tunable Fano resonance induced by strong coupling between Weyl fermions and phonons in TaAs. Nat Commun 2017; 8:14933. [PMID: 28358027 PMCID: PMC5379101 DOI: 10.1038/ncomms14933] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [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: 09/01/2016] [Accepted: 02/09/2017] [Indexed: 11/30/2022] Open
Abstract
Strong coupling between discrete phonon and continuous electron–hole pair excitations can induce a pronounced asymmetry in the phonon line shape, known as the Fano resonance. This effect has been observed in various systems. Here we reveal explicit evidence for strong coupling between an infrared-active phonon and electronic transitions near the Weyl points through the observation of a Fano resonance in the Weyl semimetal TaAs. The resulting asymmetry in the phonon line shape, conspicuous at low temperatures, diminishes continuously with increasing temperature. This behaviour originates from the suppression of electronic transitions near the Weyl points due to the decreasing occupation of electronic states below the Fermi level (EF) with increasing temperature, as well as Pauli blocking caused by thermally excited electrons above EF. Our findings not only elucidate the mechanism governing the tunable Fano resonance but also open a route for exploring exotic physical phenomena through phonon properties in Weyl semimetals. The study of lattice vibrations coupled to electronic excitations may provide an avenue for exploring exotic physical phenomena. Here, Xu et al. observe a Fano resonance in the Weyl semimetal TaAs, revealing evidence for a strong coupling between phonons and Weyl fermions.
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Affiliation(s)
- B Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China.,Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - Y M Dai
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - L X Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - K Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - R Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - W Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - J Y Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - H Xiao
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - G F Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - S A Trugman
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.,Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J-X Zhu
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.,Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A J Taylor
- Associate Directorate for Chemistry, Life and Earth Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - D A Yarotski
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R P Prasankumar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - X G Qiu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
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7
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Liu Y, Long YJ, Zhao LX, Nie SM, Zhang SJ, Weng YX, Jin ML, Li WM, Liu QQ, Long YW, Yu RC, Gu CZ, Sun F, Yang WG, Mao HK, Feng XL, Li Q, Zheng WT, Weng HM, Dai X, Fang Z, Chen GF, Jin CQ. Superconductivity in HfTe 5 across weak to strong topological insulator transition induced via pressures. Sci Rep 2017; 7:44367. [PMID: 28300156 PMCID: PMC5353664 DOI: 10.1038/srep44367] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [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: 10/03/2016] [Accepted: 02/07/2017] [Indexed: 11/17/2022] Open
Abstract
Recently, theoretical studies show that layered HfTe5 is at the boundary of weak & strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice parameters. The topological properties of 3D stacked HfTe5 are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic & crystal structures for HfTe5 with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe5 crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe5 transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe5 is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.
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Affiliation(s)
- Y Liu
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Y J Long
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - L X Zhao
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - S M Nie
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - S J Zhang
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Y X Weng
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - M L Jin
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - W M Li
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Q Q Liu
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Y W Long
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - R C Yu
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - C Z Gu
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - F Sun
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - W G Yang
- Center for High Pressure Science &Technology Advanced Research, Shanghai, 201203, China
| | - H K Mao
- Center for High Pressure Science &Technology Advanced Research, Shanghai, 201203, China
| | - X L Feng
- Department of Materials Science, Jilin University, Changchun 130012, China
| | - Q Li
- Department of Materials Science, Jilin University, Changchun 130012, China
| | - W T Zheng
- Department of Materials Science, Jilin University, Changchun 130012, China
| | - H M Weng
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - X Dai
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Z Fang
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - G F Chen
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - C Q Jin
- Institute of Physics &School of Physics of University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
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8
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Shao P, Xu ZR, Zhao LX, Zhao ZH. [Effect of inserted angle on the stability of loaded microscrews]. Zhonghua Kou Qiang Yi Xue Za Zhi 2017; 52:39-43. [PMID: 28072993 DOI: 10.3760/cma.j.issn.1002-0098.2017.01.008] [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: 06/06/2023]
Abstract
Objective: To evaluate the effect of different insertion angles on the osseointegration of loaded microscrews in beagle jaws. Methods: Forty-eight microscrews were inserted at four different angles (30°, 50°, 70° and 90°) into the interradicular zones between the mandibular first molar and third premolar in twelve beagles and the microscrews had been loaded with a force of 2 N immediately for 8 weeks. After microscrew-bone specimens fixed, the maximum output value (Fmax) of pull-out test was recorded and the histomorphological changes of hard tissue were observed. The bone-implant contact (BIC%) was quantitatively analyzed and the osseointegration of microscrew-bone interface was comprehensively evaluated. Results: Both Fmax and BIC% values of microscrews were influenced by the insertion angles. The maximum value of Fmax was (385±23) N in the group with 50° angle, and the minimum value was (198±16) N in the group with 30° angle(P <0.05). The maximum value of BIC% was (59.1±6.0)% in the group with 70° angle, and the minimum value was (30.2±3.2)% in the group with 30° angle (P <0.05). Histomorphology observation revealed that in peri-screws region, the various degree of bone remodeling was found in different angle samples. Conclusions: The insertion angles (50°and 70°) were favorable to the stability of the microscrew.
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Affiliation(s)
- P Shao
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China (Present address: Department of Stomatology, 363 Hospital of China Aviation Industry, Chengdu 610041, China)
| | - Z R Xu
- Department of Orthodontics, Jinqin International Dental Clinic-Shuangnan Branch, Chengdu 610041, China
| | - L X Zhao
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China
| | - Z H Zhao
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China
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9
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Abstract
We report a comparative polarized Raman study of Weyl semimetals TaAs, NbAs, TaP and NbP. The evolution of the phonon frequencies with the sample composition allows us to determine experimentally which atoms are mainly involved for each vibration mode. Our results confirm previous first-principles calculations indicating that the A1, B1(2), E(2) and E(3) modes involve mainly the As(P) atoms, the B1(1) mode is mainly related to Ta(Nb) atoms, and the E(1) mode involves both kinds of atoms. By comparing the energy of the different modes, we establish that the B1(1), B1(2), E(2) and E(3) become harder with increasing chemical pressure. This behaviour differs from our observation on the A1 mode, which decreases in energy, in contrast to its behaviour under external pressure.
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Affiliation(s)
- H W Liu
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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10
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Hu XL, Sun LB, Zeng B, Wang LS, Yu ZG, Bai SA, Yang SM, Zhao LX, Li Q, Qiu M, Tai RZ, Fecht HJ, Jiang JZ, Zhang DX. Polarization-independent plasmonic subtractive color filtering in ultrathin Ag nanodisks with high transmission. Appl Opt 2016; 55:148-152. [PMID: 26835634 DOI: 10.1364/ao.55.000148] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate a TE/TM polarization-independent plasmonic subtractive color filtering scheme employing ultrathin two-dimensional Ag nanodisks. These TE/TM polarization-independent subtractive color filters exhibit small feature sizes (below 200 nm) and high transmission up to 70% in the visible spectral region, superior to previously reported plasmonic color filters. Simulated optical transmission spectra and colors are in good agreement with experimental results. The color-filtering behaviors strongly depend on thickness and period of nanodisks. Underlying mechanisms are also discussed in detail.
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11
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Lv BQ, Muff S, Qian T, Song ZD, Nie SM, Xu N, Richard P, Matt CE, Plumb NC, Zhao LX, Chen GF, Fang Z, Dai X, Dil JH, Mesot J, Shi M, Weng HM, Ding H. Observation of Fermi-Arc Spin Texture in TaAs. Phys Rev Lett 2015; 115:217601. [PMID: 26636872 DOI: 10.1103/physrevlett.115.217601] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Indexed: 06/05/2023]
Abstract
We have investigated the spin texture of surface Fermi arcs in the recently discovered Weyl semimetal TaAs using spin- and angle-resolved photoemission spectroscopy. The experimental results demonstrate that the Fermi arcs are spin polarized. The measured spin texture fulfills the requirement of mirror and time-reversal symmetries and is well reproduced by our first-principles calculations, which gives strong evidence for the topologically nontrivial Weyl semimetal state in TaAs. The consistency between the experimental and calculated results further confirms the distribution of chirality of the Weyl nodes determined by first-principles calculations.
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Affiliation(s)
- B Q Lv
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - S Muff
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - T Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Z D Song
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - S M Nie
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - N Xu
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - P Richard
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - L X Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - G F Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Z Fang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - X Dai
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - J H Dil
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - H M Weng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
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12
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Abstract
Genomic imprinting and DNA methylation play an important role in mammalian development. Many cloned animals showed heterogeneous DNA methylation profiles. However, there are fewer reports in cloned lambs because of a lack of genomic imprinting information. In this study, we investigated DNA methylation patterns in CpG islands and differentially methylated regions of putative imprinted gene Peg10 and imprinted genes Dlk1, Igf2R and H19 in cloned lambs. Five organs from two cloned lambs died shortly after birth and two normal controls were investigated. We observed normal DNA methylation profiles in cloned lambs. The imprinted genes Dlk1, Igf2R and H19 in livers, kidneys, hearts, muscles and lungs of the two cloned lambs exhibited relatively normal DNA methylation, except for Peg10 showing some differences between controls and cloned lambs. Our results indicate that somatic cell nuclear transfer-produced sheep exhibited relatively normal DNA methylation pattern and experienced normal DNA methylation reprogramming at imprinted loci.
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Affiliation(s)
- L X Zhao
- College of Bioengineering, Inner Mongolia Agricultural University, Hohhot, China
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13
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Chen ZJ, Li M, Li Y, Zhao LX, Tang R, Sheng Y, Gao X, Chang CH, Feng HL. Effects of sucrose concentration on the developmental potential of human frozen–thawed oocytes at different stages of maturity. Hum Reprod 2004; 19:2345-9. [PMID: 15298975 DOI: 10.1093/humrep/deh442] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [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: 11/12/2022] Open
Abstract
BACKGROUND Success of human oocyte cryopreservation depends on multiple cryobiological factors that could influence the developmental potential of the oocytes. The objective of this study was to examine the effects of different sucrose concentrations on the developmental potential of human frozen-thawed oocytes at different maturity stages. METHODS A total of 355 oocytes collected from small follicles were randomly divided into three groups and two groups (B and C) were cryopreserved using slow-freezing method. Group A included 131 oocytes at different maturity stages without freezing. Another 119 oocytes in Group B were cryopreserved with 0.1 M sucrose and 105 oocytes in Group C with 0.2 M sucrose concentration. RESULTS The post-thaw survival rate of the oocytes and the cleavage rate in Group C were significantly higher than that of Group B (P<0.05). For immature metaphase I (MI) stage oocytes, a significant difference was found in the maturation rate between Group C and Group B (P<0.05). The maturation rate for the GV oocytes in Groups A and C was significantly higher than Group B (P<0.01). CONCLUSIONS The results suggested that sucrose concentration of 0.2 M in the cryoprotectant solution is more suitable for human oocyte cryopreservation.
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Affiliation(s)
- Z J Chen
- Center for Reproductive Medicine, Shandong Provincial Hospital, Shandong University, Jinan 250021, China
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14
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Foxon CT, Novikov SV, Belyaev AE, Zhao LX, Makarovsky O, Walker DJ, Eaves L, Dykeman RI, Danylyuk SV, Vitusevich SA, Kappers MJ, Barnard JS, Humphreys CJ. Current–voltage instabilities in GaN/AlGaN resonant tunnelling structures. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/pssc.200303376] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Yamano G, Funahashi H, Kawanami O, Zhao LX, Ban N, Uchida Y, Morohoshi T, Ogawa J, Shioda S, Inagaki N. ABCA3 is a lamellar body membrane protein in human lung alveolar type II cells. FEBS Lett 2001; 508:221-5. [PMID: 11718719 DOI: 10.1016/s0014-5793(01)03056-3] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.7] [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: 11/20/2022]
Abstract
The ABCA3 gene, of the ABCA subclass of ATP-binding cassette (ABC) transporters, is expressed exclusively in lung. We report here the cloning, molecular characterization, and distribution of human ABCA3 in the lung. Immunoblot analysis using the specific antibody reveals a 150-kDa protein in the crude membrane fraction of human lung. Immunohistochemical analyses of alveoli show that ABCA3 is expressed only in the type II cells expressing surfactant protein A. At the ultrastructural level, ABCA3 immunoreactivity was detected mostly at the limiting membrane of the lamellar bodies. Since members of the ABCA transporter family are known to be involved in transmembrane transport of endogenous lipids, our findings suggest that ABCA3 plays an important role in the formation of pulmonary surfactant in type II cells.
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Affiliation(s)
- G Yamano
- Department of Physiology, Akita University School of Medicine, Japan
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16
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Qin T, Xu XB, Zhao LX, Jin ZL. In vivo inhibition of multivitamin on the formation of hemoglobin adduct in 4-aminobiphenyl-treated rat. Bull Environ Contam Toxicol 2001; 67:649-656. [PMID: 11911633 DOI: 10.1007/s001280173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- T Qin
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, People's Republic of China
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17
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Zhao LX, Kim TS, Ahn SH, Kim TH, Kim EK, Cho WJ, Choi H, Lee CS, Kim JA, Jeong TC, Chang CJ, Lee ES. Synthesis, topoisomerase I inhibition and antitumor cytotoxicity of 2,2':6',2"-, 2,2':6',3"- and 2,2':6',4"-terpyridine derivatives. Bioorg Med Chem Lett 2001; 11:2659-62. [PMID: 11551772 DOI: 10.1016/s0960-894x(01)00531-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [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: 10/27/2022]
Abstract
For the development of new anticancer agents, 2,2':6',2"-, 2,2':6',3"- and 2,2':6',4"-terpyridine derivatives were designed and evaluated for their topoisomerase I inhibitory activity and antitumor cytotoxicity. Structure-activity relationship studies indicated that 2,2':6',2"-terpyridine derivatives were highly cytotoxic toward several human tumor cell lines, whereas 2,2':6',3"- and 2,2':6',4"-terpyridine derivatives were potent topoisomerase I inhibitors.
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Affiliation(s)
- L X Zhao
- College of Pharmacy, Yeungnam University, Kyongsan 712-749, South Korea
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18
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19
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Zhao LX, Zhou CJ, Tanaka A, Nakata M, Hirabayashi T, Amachi T, Shioda S, Ueda K, Inagaki N. Cloning, characterization and tissue distribution of the rat ATP-binding cassette (ABC) transporter ABC2/ABCA2. Biochem J 2000; 350 Pt 3:865-72. [PMID: 10970803 PMCID: PMC1221321] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The ABC1 (ABCA) subfamily of the ATP-binding cassette (ABC) transporter superfamily has a structural feature that distinguishes it from other ABC transporters. Here we report the cloning, molecular characterization and tissue distribution of ABC2/ABCA2, which belongs to the ABC1 subfamily. Rat ABC2 is a protein of 2434 amino acids that has 44.5%, 40.0% and 40.8% identity with mouse ABC1/ABCA1, human ABC3/ABCA3 and human ABCR/ABCA4 respectively. Immunoblot analysis showed that proteins of 260 and 250 kDa were detected in COS-1 cells transfected with ABC2 having a haemagglutinin tag, while no band was detected in mock-transfected cells. After incubation with N-glycosidase F, the mobilities of the two proteins increased and a single band was detected, suggesting that ABC2 is a glycoprotein. Photoaffinity labelling with 8-azido-[alpha-(32)P]ATP confirmed that ATP binds to the ABC2 protein in the presence of Mg(2+). RNA blot analysis showed that ABC2 mRNA is most abundant in rat brain. Examination of brain by in situ hybridization determined that ABC2 is expressed at high levels in the white matter, indicating that it is expressed in the oligodendrocytes. ABC2, therefore, is a glycosylated ABC transporter protein, and may play an especially important role in the brain. In addition, the N-terminal 60-amino-acid sequence of the human ABC1, which was missing from previous reports, has been determined.
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Affiliation(s)
- L X Zhao
- Department of Physiology, Akita University School of Medicine, 1-1-1, Hondo, Akita 010-8543, Japan
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20
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Kim YC, Zhao LX, Kim TH, Je SM, Kim EK, Choi H, Chae WG, Park M, Choi J, Jahng Y, Lee ES. Design and synthesis of anticonvulsive agents as gamma-vinyl GABA-based potential dual acting prodrugs and their biological activities. Bioorg Med Chem Lett 2000; 10:609-13. [PMID: 10762036 DOI: 10.1016/s0960-894x(00)00064-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [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: 11/22/2022]
Abstract
For the development of new anticonvulsive agents, gamma-vinyl GABA (vigabatrin) and GABA mimetics derivatives were covalently coupled as potential dual acting prodrugs and evaluated for their anticonvulsive activities. Among the prepared compounds, 11 showed the most potent anticonvulsive activity, a shorter onset time and a broader spectrum compared to vigabatrin.
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Affiliation(s)
- Y C Kim
- College of Pharmacy, Yeungnam University, Kyongsan, South Korea
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21
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Ma MY, Xu XH, Luo B, Zhu JZ, Chen JG, Zhao LX, Wang HY. [Immunohistochemical study on myocardial acute ischemia reperfusion injury in rats with anti-FOS protein antibody]. Fa Yi Xue Za Zhi 1999; 15:193-5, 254. [PMID: 12536430] [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: 02/28/2023]
Abstract
To investigate law of FOS protein induced by myocardial ischemia reperfusion (MI/R) in acute period, a model in 20 anaethetized SD rats was established. Rats with normal and ischemia were used as control groups. Specimens were studied immunohistochemically with c-fos antibody. After ischemia 20 minutes, followed by 30 minutes reperfusion, the area of MI/R showed nuclei of myocytes positive staining in cryosection slides. In C2 group, the area showed nuclei of myocytes (37.76% +/- 9.66%) positive staining weakly. In C3 group, nuclei of cardiac myocytes(40.34% +/- 3.32%) was significantly positive. In C4 group it began to attenuate(35.36% +/- 4.81%). The myocardium in normal and ischemic control groups showed negative staining. No changes were seen with HE staining. Our data indicated that immunohistochemical method may reveal acute MI/R injury of ischemia 20 min and reperfusion 30 min with anti-FOS protein staining and there is problely a peak between 60-120 min after reperfusion. It is possible that the method be used to diagnose sudden cardiac death in forensic medicine.
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Affiliation(s)
- M Y Ma
- Department of Forensic Pathology, Sun Yat-Sen University of Medical Sciences, GuangZhou 510089, P. R. China
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22
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Xu LH, Tiang YQ, Zhang YF, Zhao LX, Jiang CL. Streptomyces thermogriseus, a new species of the genus Streptomyces from soil, lake and hot-spring. Int J Syst Bacteriol 1998; 48 Pt 4:1089-93. [PMID: 9828410 DOI: 10.1099/00207713-48-4-1089] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Many thermophilic actinomycetes were isolated from samples collected from a hot-spring, lake and soil in Yunnan, China. Chemical and molecular classification of four selected strains of thermophilic Streptomyces with an upper limited growth temperature of 65-68 degrees C and autolytic characteristics was carried out. A new species, Streptomyces thermogriseus sp. nov. is described. The type strain is Y-14046T (= CCTCC AA97014T).
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Affiliation(s)
- L H Xu
- Yunnan Institute of Microbiology, Yunnan University, Kunming, China
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23
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Zhao LX. [X-ray diagnosis of neuroblastoma (a report of 5 cases) (author's transl)]. Zhonghua Fang She Xue Za Zhi 1980; 14:274-67. [PMID: 6454556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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