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Chen CY, Hsu MC, Hu CD, Lin YC. Natural Negative-Refractive-Index Materials. Phys Rev Lett 2021; 127:237401. [PMID: 34936775 DOI: 10.1103/physrevlett.127.237401] [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: 03/18/2021] [Accepted: 11/02/2021] [Indexed: 06/14/2023]
Abstract
Our calculation shows that negative refractive index (NRI), which was known to exist only in metamaterials in the past, can be found in Dirac semimetals (DSM). Electrons in DSM have zero effective mass and hence the system carries no nominal energy scale. Therefore, unlike those of ordinary materials, the electromagnetic responses of the electrons in DSM will not be overwhelmed by the physical effects related to electron mass. NRI is induced by the combination of the quantum effect of vacuum polarization and its finite temperature correction, which is proportional to T^{4} at low temperature. It is a phenomenon of resonance between the incident light and the unique structure of Dirac cones, which allows numerous states to participate in electron-hole pair production excited by the incident light with a similar dispersion relation to that of Dirac cones. The NRI phenomenon of DSM manifests in an extensive range of photon frequencies and wave numbers and can be observed around the gigahertz range at room temperature.
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Affiliation(s)
- Chih-Yu Chen
- National Taiwan University, 106319 Taipei, Taiwan
- Chung Yuan Christian University, 320314 Taoyuan, Taiwan
| | - Ming-Chien Hsu
- National Sun Yat-Sen University, 804201 Kaohsiung, Taiwan
| | - C D Hu
- National Taiwan University, 106319 Taipei, Taiwan
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Wang R, Xu Y, Jiang C, Peng X, Yu Z, Xie Y, Xie Y, Hu C. Simulation and analysis of charge accumulation characteristics of post insulator of transmission line for the CRAFT NNBI system. Fusion Engineering and Design 2021. [DOI: 10.1016/j.fusengdes.2021.112948] [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: 11/28/2022]
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3
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Hu C, Wang R, Jiang C, Xu Y, Xie Y, Xie Y. Preliminary insulation design for transmission line of CFETR NNBI test platform. Fusion Engineering and Design 2020. [DOI: 10.1016/j.fusengdes.2020.112062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zheng LP, Shen WA, Wang CH, Hu CD, Chen XJ, Shen YY, Wang J. Anastomosing hemangioma arising from the left renal vein: A case report. World J Clin Cases 2020; 8:4986-4992. [PMID: 33195671 PMCID: PMC7642539 DOI: 10.12998/wjcc.v8.i20.4986] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/14/2020] [Accepted: 09/09/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Anastomosing hemangioma (AH) is a rare subtype of benign hemangioma that is most commonly found in the genitourinary tract. Due to the lack of specific clinical and radiologic manifestations, it is easily misdiagnosed preoperatively. Here, we report a case of AH arising from the left renal vein that was discovered incidentally and confirmed pathologically, and then describe its imaging characteristics from a radiologic point of view and review its clinicopathologic features and treatment.
CASE SUMMARY A 74-year-old woman was admitted to our department for a left retroperitoneal neoplasm measuring 2.6 cm × 2.0 cm. Her laboratory data showed no significant abnormalities. A non-contrast-enhanced computed tomography (CT) scan showed a heterogeneous density in the neoplasm. Non-contrast-enhanced magnetic resonance imaging (MRI) revealed a heterogeneous hypointensity on T1-weighed images and a heterogeneous hyperintensity on T2-weighed images. On contrast-enhanced CT and MRI scans, the neoplasm presented marked septal enhancement in the arterial phase and persistent enhancement in the portal phase, and its boundary with the left renal vein was ill-defined. Based on these clinical and radiological manifestations, the neoplasm was initially considered to be a neurogenic neoplasm in the left retroperitoneum. Finally, the neoplasm was completely resected and pathologically diagnosed as AH.
CONCLUSION AH is an uncommon benign hemangioma. Preoperative misdiagnoses are common not only because of a lack of specific clinical and radiologic manifestations but also because clinicians lack vigilance and diagnostic experience in identifying AH. AH is not exclusive to the urogenital parenchyma. We report the first case of this neoplasm in the left renal vein. Recognition of this entity in the left renal vein can be helpful in its diagnosis and distinction from other neoplasms.
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Affiliation(s)
- Li-Ping Zheng
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Wei-Ai Shen
- University of Ningbo, Ningbo 315000, Zhejiang Province, China
| | - Chun-Hua Wang
- Department of Pathology, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Chun-Dong Hu
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Xu-Jian Chen
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Yi-Yu Shen
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Jing Wang
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
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Zheng LP, Hu CD, Wang J, Chen XJ, Shen YY. Radiological aspects of giant hepatocellular adenoma of the left liver: A case report. World J Clin Cases 2019; 7:4111-4118. [PMID: 31832416 PMCID: PMC6906579 DOI: 10.12998/wjcc.v7.i23.4111] [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] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/16/2019] [Accepted: 11/19/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Hepatocellular adenoma (HCA) is very rare and has a high misdiagnosis rate through clinical and imaging examinations. We report a case of giant HCA of the left liver in a young woman that was diagnosed by medical imaging and pathology.
CASE SUMMARY A 21-year-old woman was admitted to our department for a giant hepatic tumor measuring 22 cm × 20 cm × 10 cm that completely replaced the left hepatic lobe. Her laboratory data only suggested mildly elevated liver function parameters and C-reactive protein levels. A computed tomography (CT) scan showed mixed density in the tumor. Magnetic resonance imaging (MRI) of the tumor revealed a heterogeneous hypointensity on T1-weighed MR images and heterogeneous hyperintensity on T2-weighed MR images. On dynamic contrast CT and MRI scans, the tumor presented marked enhancement and the subcapsular feeding arteries were clearly visible in the arterial phase, with persistent enhancement in the portal and delayed phases. Moreover, the tumor capsule was especially prominent on T1-weighted MR images and showed marked enhancement in the delayed phase. Based on these imaging manifestations, the tumor was initially considered to be an HCA. Subsequently, the tumor was completely resected and pathologically diagnosed as an HCA.
CONCLUSION HCA is an extremely rare hepatic tumor. Preoperative misdiagnoses were common not only due to the absence of special clinical manifestations and laboratory examination findings, but also due to the clinicians’ lack of practical diagnostic experience and vigilance in identifying HCA on medical images. Our case highlights the importance of the combination of contrast-enhanced CT and MRI in the preoperative diagnosis of HCA.
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Affiliation(s)
- Li-Ping Zheng
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Chun-Dong Hu
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Jing Wang
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Xu-Jian Chen
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
| | - Yi-Yu Shen
- Department of General Surgery, The Second Affiliated Hospital of Jiaxing University, Jiaxing 314000, Zhejiang Province, China
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Wei JL, Liang LZ, Jiang CC, Xie YH, Hu CD, Li J, Gu YM, Chen YQ, Li JY, Wu MS. Beam optics study of a negative ion source for neutral beam injection application at ASIPP. Fusion Engineering and Design 2017. [DOI: 10.1016/j.fusengdes.2017.02.089] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Jiang CC, Hu CD, Xie YH, Liu S, Chen SY, Liu ZM, Xu YJ, Liang LZ, Xie YL. Development of a core snubber for the neutral beam injector on EAST. Rev Sci Instrum 2016; 87:123302. [PMID: 28040958 DOI: 10.1063/1.4972883] [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] [Indexed: 06/06/2023]
Abstract
A 4-MW ion source was developed for the neutral beam injector (NBI) on Experimental Advanced Superconducting Tokamak (EAST). Breakdown nevertheless can happen during ion source conditioning and routine operations and is deleterious to the high-power ion source. To protect this ion source, a core snubber was designed to absorb the breakdown energy of the EAST-NBI ion source. A prototype core snubber was developed and tested using the ion-source test bed. The results show that with a core snubber, short-circuit currents at different high-power voltages were about one-tenth of the current without the snubber. The residual energy of the distributed capacitors had been absorbed successfully and the core snubber does protect the source from damage during breakdown. The results verified the successful development of a core snubber for the EAST-NBI.
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Affiliation(s)
- Cai-Chao Jiang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Chun-Dong Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Ya-Hong Xie
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Sheng Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Shi-Yong Chen
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhi-Min Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Yong-Jian Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Li-Zhen Liang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Yuan-Lai Xie
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
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Wei JL, Hu CD, Jiang CC, Liu S, Tao L, Gu YM, Zhao YZ, Chen YQ, Wu MS. Conceptual design of magnetic filter for the prototype negative ion source at ASIPP. Fusion Engineering and Design 2016. [DOI: 10.1016/j.fusengdes.2016.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Li YY, Yin XH, Fu J, Jiang D, Feng SY, Lyu B, Shi YJ, Yi Y, Zhou XJ, Hu CD, Ye MY, Wan BN. First measurement of the edge charge exchange recombination spectroscopy on EAST tokamak. Rev Sci Instrum 2016; 87:11E501. [PMID: 27910523 DOI: 10.1063/1.4955279] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An edge toroidal charge exchange recombination spectroscopy (eCXRS) diagnostic, based on a heating neutral beam injection (NBI), has been deployed recently on the Experimental Advanced Superconducting Tokamak (EAST). The eCXRS, which aims to measure the plasma ion temperature and toroidal rotation velocity in the edge region simultaneously, is a complement to the exiting core CXRS (cCXRS). Two rows with 32 fiber channels each cover a radial range from ∼2.15 m to ∼2.32 m with a high spatial resolution of ∼5-7 mm. Charge exchange emission of Carbon VI CVI at 529.059 nm induced by the NBI is routinely observed, but can be tuned to any interested wavelength in the spectral range from 400 to 700 nm. Double-slit fiber bundles increase the number of channels, the fibers viewing the same radial position are binned on the CCD detector to improve the signal-to-noise ratio, enabling shorter exposure time down to 5 ms. One channel is connected to a neon lamp, which provides the real-time wavelength calibration on a shot-to-shot basis. In this paper, an overview of the eCXRS diagnostic on EAST is presented and the first results from the 2015 experimental campaign will be shown. Good agreements in ion temperature and toroidal rotation are obtained between the eCXRS and cCXRS systems.
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Affiliation(s)
- Y Y Li
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - X H Yin
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J Fu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - D Jiang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - S Y Feng
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - B Lyu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - Y J Shi
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, China
| | - Y Yi
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, China
| | - X J Zhou
- Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| | - C D Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - M Y Ye
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, China
| | - B N Wan
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
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Abstract
We investigate the effect of the Rashba interaction on two dimensional superconductivity. The presence of the Rashba interaction lifts the spin degeneracy and gives rise to the spectrum of two bands. There are intraband and interband pairs scattering which result in the coupled gap equations. We find that there are isotropic and anisotropic components in the gap function. The latter has the form of cos φk where . The former is suppressed because the intraband and the interband scatterings nearly cancel each other. Hence, −the system should exhibit the p-wave superconductivity. We perform a detailed study of electron-phonon interaction for 2DEG and find that, if only normal processes are considered, the effective coupling strength constant of this new superconductivity is about one-half of the s-wave case in the ordinary 2DEG because of the angular average of the additional in the anisotropic gap function. By taking into account of Umklapp processes, we find they are the major contribution in the electron-phonon coupling in superconductivity and enhance the transition temperature Tc.
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Affiliation(s)
- Ke-Chuan Weng
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan.,Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan.,Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - C D Hu
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan.,Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
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Xu YJ, Hu CD, Yu L, Liang LZ, Zhang WT, Chen Y, Li X. Progress of beam diagnosis system for EAST neutral beam injector. Rev Sci Instrum 2016; 87:02B934. [PMID: 26932106 DOI: 10.1063/1.4936998] [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] [Indexed: 06/05/2023]
Abstract
Neutral beam injection has been recognized as one of the most effective means for plasma heating. According to the research plan of the EAST physics experiment, two sets of neutral beam injector (NBI) were built and operational in 2014. The paper presents the development of beam diagnosis system for EAST NBI and the latest experiment results obtained on the test-stand and EAST-NBI-1 and 2. The results show that the optimal divergence angle is (0.62°, 1.57°) and the full energy particle is up to 77%. They indicate that EAST NBI work properly and all targets reach or almost reach the design targets. All these lay a solid foundation for the achievement of high quality plasma heating for EAST.
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Affiliation(s)
- Y J Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - C D Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - L Yu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - L Z Liang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - W T Zhang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Y Chen
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - X Li
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
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Ou-Yang TY, Shu GJ, Lin JY, Hu CD, Chou FC. Mn vacancy defects, grain boundaries, and A-phase stability of helimagnet MnSi. J Phys Condens Matter 2016; 28:026004. [PMID: 26683210 DOI: 10.1088/0953-8984/28/2/026004] [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] [Indexed: 06/05/2023]
Abstract
Mn vacancy defect and grain size are shown to modify the magnetic phase diagram of MnSi significantly, especially near the critical regime of A-phase (skyrmion lattice) formation and the helimagnetic phase transition. Crystals grown using controlled nonstoichiometric initial precursors creates both grain boundaries and intrinsic Mn vacancy defect of various levels in MnSi. The results of combined transport, specific heat, and AC spin susceptibility measurements are compared for MnSi single crystal samples of various manganese deficiency levels and grain sizes. The finite-size effect and Mn vacancy level dependent helical phase transition temperature T(c) have been identified and verified. The stability of A-phase in H-T phase space has been examined through AC spin susceptibility data analysis.
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Affiliation(s)
- T Y Ou-Yang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
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Jiang CC, Xie YH, Hu CD, Xie YL, Liu S, Liang LZ, Liu ZM. Note: A new regulation method of stable operation of high power cathode ion source. Rev Sci Instrum 2015; 86:056110. [PMID: 26026571 DOI: 10.1063/1.4921705] [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] [Indexed: 06/04/2023]
Abstract
The hot cathode ion source will tend to be unstable when operated with high power and long pulse. In order to achieve stable operation, a new regulation method based on the arc power (discharge power) feedback control was designed and tested on the hot cathode ion source test bed with arc discharge and beam extraction. The results show that the new regulation method can achieve stable arc discharge and beam extraction. It verifies the success of feedback control of arc source with arc power.
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Affiliation(s)
- C C Jiang
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
| | - Y H Xie
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
| | - C D Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
| | - Y L Xie
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
| | - S Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
| | - L Z Liang
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
| | - Z M Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031, China
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Wang Y, Wu B, Liang LZ, Hu CD, Wei JL, Zhao XX. Beam Species Evolution Under Long Pulse Operation for EAST-NBI by Doppler Shift Spectroscopy Diagnostic System. J Fusion Energ 2015. [DOI: 10.1007/s10894-015-9852-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Liu X, Xu J, Hu CD, Pan ZL, Zhang YC. The relationship between SNPs in the genes of TLR signal transduction pathway downstream elements and rheumatoid arthritis susceptibility. CYTOL GENET+ 2014. [PMID: 25016825 DOI: 10.3103/s0095452714030074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Toll-like receptors (TLRs) play an important role in the induction and regulation of the innate immune system or adaptive immune responses. Genetic variations within human TLRs have been reported to be associated with rheumatoid arthritis (RA). This study was conducted to investigate correlation between SNP of downstream mononucleotide in signal transduction of Toll-like receptors and predisposing genes of RA. There was obviously correlative between single nucleotide polymorphism and predisposing genes of RA. G-type of IL-1RAP rs766442 may be protecting genes of RA, while T-type alleles of IL-6R rs11265618 and IL-1RAP rs766442 may be susceptible genes of RA. In conclusion, the studies on the nucleis acid polymorphism in TLRs signal pathway contribute to disclose genes' influence on the attack mechanism of RA, early diagnosis and treatment of RA.
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Wei JL, Li J, Hu CD, Xie YH, Jing H. Investigation of the adhesive bonding technology for the insulator structure of EAST neutral beam injector. Rev Sci Instrum 2014; 85:073504. [PMID: 25085137 DOI: 10.1063/1.4890563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A key issue on the development of EAST ion source was the junction design of insulator structure, which consists of three insulators and four supporting flanges of electrode grid. Because the ion source is installed on the vertical plane, the insulator structure has to withstand large bending and shear stress due to the gravity of whole ion source. Through a mechanical analysis, it was calculated that the maximum bending normal stress was 0.34 MPa and shear stress was 0.23 MPa on the insulator structure. Due to the advantages of simplicity and high strength, the adhesive bonding technology was applied to the junction of insulator structure. A tensile testing campaign of different junction designs between insulator and supporting flange was performed, and a junction design of stainless steel and fiber enhanced epoxy resin with epoxy adhesive was determined. The insulator structure based on the determined design can satisfy both the requirements of high-voltage holding and mechanical strength.
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Affiliation(s)
- Jiang-Long Wei
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Jun Li
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Chun-Dong Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Ya-Hong Xie
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Hao Jing
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
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Wei JL, Hu CD, Liang LZ, Liu ZW. Modeling the gas flow in the neutralizer of ITER neutral beam injector using Direct Simulation Monte Carlo approach. Fusion Engineering and Design 2013. [DOI: 10.1016/j.fusengdes.2012.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
The Dzyaloshinskii-Moriya (DM) interaction in metals is an important mechanism for many magnetic properties. We start with the s-d exchange model and spin-orbit interaction for weak itinerant ferromagnetic systems to establish the form of DM interaction for metallic magnetic systems. The s-d exchange interaction is treated accurately and the conduction electron-mediated magnetism gives a form of DM interaction which is different from that in insulators. The implications of our result to spiral spin states and skyrmion lattices are also discussed.
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Affiliation(s)
- C D Hu
- Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei, Taiwan, Republic of China
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Hu CD. Some fermi surface properties of double-exchange interaction systems. Phys Rev Lett 2004; 93:157205. [PMID: 15524936 DOI: 10.1103/physrevlett.93.157205] [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: 03/01/2004] [Indexed: 05/24/2023]
Abstract
We study the photoemission spectrum of the double-exchange (DE) interaction systems. The DE Hamiltonian can be transformed into a simple form consisting of fermions and Schwinger bosons. We apply the gauge-field model and calculate the Green's function of the gauge field, fermions, and bosons. The imaginary part of the Green's function of an electron has an asymmetrical peak with strong temperature dependence. This can explain why the shape of the angle-resolved photoemission spectra of manganites near the Fermi surface is very different from that of Fermi liquid. We also show why the position of the Fermi surface is not sensitive to temperature.
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Affiliation(s)
- C D Hu
- Department of Physics and NCTS at TPE, National Taiwan University, Taipei, Taiwan, Republic of China
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Gao X, Satoh T, Liao Y, Song C, Hu CD, Kariya Ki K, Kataoka T. Identification and characterization of RA-GEF-2, a Rap guanine nucleotide exchange factor that serves as a downstream target of M-Ras. J Biol Chem 2001; 276:42219-25. [PMID: 11524421 DOI: 10.1074/jbc.m105760200] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [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: 11/06/2022] Open
Abstract
The Ras family small GTPase Rap is regulated by an array of specific guanine nucleotide exchange factors (GEFs) in response to upstream stimuli. RA-GEF-1 was identified as a novel Rap GEF, which possesses a Ras/Rap1-associating (RA) domain. Here we report a protein closely related to RA-GEF-1, named RA-GEF-2. Like RA-GEF-1, a putative cyclic nucleotide monophosphate-binding domain, a Ras exchanger motif, a PSD-95/DlgA/ZO-1 domain, and an RA domain in addition to the GEF catalytic domain are found in RA-GEF-2. However, RA-GEF-2 displays a different tissue distribution profile from that of RA-GEF-1. RA-GEF-2 stimulates guanine nucleotide exchange of both Rap1 and Rap2, but not Ha-Ras. The RA domain of RA-GEF-2 binds to M-Ras in a GTP-dependent manner, but not to other Ras family GTPases tested, including Ha-Ras, N-Ras, Rap1A, Rap2A, R-Ras, RalA, Rin, Rit, and Rheb, in contrast to the RA domain of RA-GEF-1, which specifically binds to Rap1. In accordance with this, RA-GEF-2 colocalizes with activated M-Ras in the plasma membrane in COS-7 cells, suggesting a role of RA-GEF-2 in the regulation of Rap1 and Rap2, particularly in the plasma membrane. In fact, an increase in the level of the GTP-bound form of plasma membrane-located Rap1 was observed when coexpressed with RA-GEF-2 and activated M-Ras. Thus, RA-GEF-2 acts as a GEF for Rap1 and Rap2 downstream of M-Ras in the plasma membrane, whereas RA-GEF-1 exerts Rap GEF function in perinuclear compartments including the Golgi apparatus.
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Affiliation(s)
- X Gao
- Division of Molecular Biology, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Japan
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22
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Jin TG, Satoh T, Liao Y, Song C, Gao X, Kariya K, Hu CD, Kataoka T. Role of the CDC25 homology domain of phospholipase Cepsilon in amplification of Rap1-dependent signaling. J Biol Chem 2001; 276:30301-7. [PMID: 11395506 DOI: 10.1074/jbc.m103530200] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [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: 11/06/2022] Open
Abstract
Phospholipase Cepsilon (PLCepsilon) is a novel class of phosphoinositide-specific PLC characterized by possession of CDC25 homology and Ras/Rap1-associating domains. We and others have shown that human PLCepsilon is translocated from the cytoplasm to the plasma membrane and activated by direct association with Ras at its Ras/Rap1-associating domain. In addition, translocation to the perinuclear region was induced upon association with Rap1.GTP. However, the function of the CDC25 homology domain remains to be clarified. Here we show that the CDC25 homology domain of PLCepsilon functions as a guanine nucleotide exchange factor for Rap1 but not for any other Ras family GTPases examined including Rap2 and Ha-Ras. Consistent with this, coexpression of full-length PLCepsilon or its N-terminal fragment carrying the CDC25 homology domain causes an increase of the intracellular level of Rap1.GTP. Concurrently, stimulation of the downstream kinases B-Raf and extracellular signal-regulated kinase is observed, whereas the intracellular level of Ras.GTP and Raf-1 kinase activity are unaffected. In wild-type Rap1-overexpressing cells, epidermal growth factor induces translocation of PLCepsilon to the perinuclear compartments such as the Golgi apparatus, which is sustained for at least 20 min. In contrast, PLCepsilon lacking the CDC25 domain translocates to the perinuclear compartments only transiently. Further, the formation of Rap1.GTP upon epidermal growth factor stimulation exhibits a prolonged time course in cells expressing full-length PLCepsilon compared with those expressing PLCepsilon lacking the CDC25 homology domain. These results suggest a pivotal role of the CDC25 homology domain in amplifying Rap1-dependent signal transduction, including the activation of PLCepsilon itself, at specific subcellular locations such as the Golgi apparatus.
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Affiliation(s)
- T G Jin
- Division of Molecular Biology, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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23
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Liao Y, Satoh T, Gao X, Jin TG, Hu CD, Kataoka T. RA-GEF-1, a guanine nucleotide exchange factor for Rap1, is activated by translocation induced by association with Rap1*GTP and enhances Rap1-dependent B-Raf activation. J Biol Chem 2001; 276:28478-83. [PMID: 11359771 DOI: 10.1074/jbc.m101737200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously identified RA-GEF-1, a novel guanine nucleotide exchange factor (GEF) for Rap1 with the ability to associate with Rap1.GTP at its Ras/Rap1-associating (RA) domain. Because it possesses a PSD-95/DlgA/ZO-1 (PDZ) domain, it was also named PDZ-GEF. In this report, we have examined the role of the RA domain of this protein in Rap1-mediated cellular responses. A mutant of RA-GEF-1 (RA-GEF-1DeltaRA) carrying a 21-residue deletion at its RA domain fully retains the in vitro GEF activity toward Rap1 but completely loses the Rap1 binding activity. In contrast, RA-GEF-1DeltaRA, expressed in COS-7 cells, exhibits a 3-fold reduction in its in vivo GEF activity toward Rap1 compared with wild-type RA-GEF-1 as examined by the Rap1 pull-down assay. Correspondingly, when coexpressed with wild-type Rap1, RA-GEF-1DeltaRA is unable to further activate B-Raf, whereas RA-GEF-1 stimulates B-Raf as efficiently as activated Rap1. Consistent with these observations, coexpression of activated Rap1 induces translocation of RA-GEF-1, which is otherwise located in the cytoplasm, to the perinuclear compartment, where Rap1 is also predominantly localized. This localization almost coincides with that of the Golgi apparatus, which was detected by anti-trans-Golgi-network 38 antibody. RA-GEF-1DeltaRA fails to show the translocation. These results indicate that RA-GEF-1 defines a novel category of GEF that is translocated to a particular subcellular compartment by association with the GTP-bound form of a small GTPase and catalyzes activation of the GDP-bound form present in the compartment, thereby causing an amplification of cellular responses induced by the small GTPase.
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Affiliation(s)
- Y Liao
- Division of Molecular Biology, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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24
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Song C, Hu CD, Masago M, Kariyai K, Yamawaki-Kataoka Y, Shibatohge M, Wu D, Satoh T, Kataoka T. Regulation of a novel human phospholipase C, PLCepsilon, through membrane targeting by Ras. J Biol Chem 2001; 276:2752-7. [PMID: 11022048 DOI: 10.1074/jbc.m008324200] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.5] [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: 01/05/2023] Open
Abstract
Phosphoinositide-specific phospholipase C (PI-PLC) plays a pivotal role in regulation of intracellular signal transduction from various receptor molecules. More than 10 members of human PI-PLC isoforms have been identified and classified into three classes beta, gamma, and delta, which are regulated by distinct mechanisms. Here we report identification of a novel class of human PI-PLC, named PLCepsilon, which is characterized by the presence of a Ras-associating domain at its C terminus and a CDC25-like domain at its N terminus. The Ras-associating domain of PLCepsilon specifically binds to the GTP-bound forms of Ha-Ras and Rap1A. The dissociation constant for Ha-Ras is estimated to be approximately 40 nm, comparable with those of other Ras effectors. Co-expression of an activated Ha-Ras mutant with PLCepsilon induces its translocation from the cytosol to the plasma membrane. Upon stimulation with epidermal growth factor, similar translocation of ectopically expressed PLCepsilon is observed, which is inhibited by co-expression of dominant-negative Ha-Ras. Furthermore, using a liposome-based reconstitution assay, it is shown that the phosphatidylinositol 4,5-bisphosphate-hydrolyzing activity of PLCepsilon is stimulated in vitro by Ha-Ras in a GTP-dependent manner. These results indicate that Ras directly regulates phosphoinositide breakdown through membrane targeting of PLCepsilon.
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Affiliation(s)
- C Song
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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Sendoh H, Hu CD, Wu D, Song C, Yamawaki-Kataoka Y, Kotani J, Okada T, Shima F, Kariya K, Kataoka T. Role of Raf-1 conserved region 2 in regulation of Ras-dependent Raf-1 activation. Biochem Biophys Res Commun 2000; 271:596-602. [PMID: 10814507 DOI: 10.1006/bbrc.2000.2674] [Citation(s) in RCA: 9] [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: 11/22/2022]
Abstract
Full activation of Raf-1 requires the interaction of its CRD with Ras. The serine/threonine-rich region, CR2, of Raf-1 was implicated in Raf-1 regulation, but the underlying mechanism was unclear. Here we show that CRD loses its Ras-binding activity when expressed in connection with CR2, suggesting that CR2 masks CRD. This masking effect is abolished by substitution of Asp or Ala for Ser-259, a growth factor- and TPA-induced phosphorylation site in CR2. Treatment of COS-7 cells expressing Ha-Ras(Val-12) and Raf-1 with TPA enhances the Ha-Ras(Val-12)-dependent Raf-1 kinase activity. In contrast, the Ha-Ras(Val-12)-dependent activities of the Raf-1(S259D) and Raf-1(S259A) mutants are comparable to that of wild-type Raf-1 stimulated by both Ha-Ras(Val-12) and TPA and cannot be further stimulated by TPA treatment. These results suggest that the in vivo phosphorylation of Ser-259 may comprise a crucial step for Ras-dependent Raf-1 activation by unmasking CRD and promoting its association with Ras.
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Affiliation(s)
- H Sendoh
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
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26
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Shima F, Okada T, Kido M, Sen H, Tanaka Y, Tamada M, Hu CD, Yamawaki-Kataoka Y, Kariya K, Kataoka T. Association of yeast adenylyl cyclase with cyclase-associated protein CAP forms a second Ras-binding site which mediates its Ras-dependent activation. Mol Cell Biol 2000; 20:26-33. [PMID: 10594005 PMCID: PMC85033 DOI: 10.1128/mcb.20.1.26-33.2000] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [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: 11/20/2022] Open
Abstract
Posttranslational modification, in particular farnesylation, of Ras is crucial for activation of Saccharomyces cerevisiae adenylyl cyclase (CYR1). Based on the previous observation that association of CYR1 with cyclase-associated protein (CAP) is essential for its activation by posttranslationally modified Ras, we postulated that the associated CAP might contribute to the formation of a Ras-binding site of CYR1, which mediates CYR1 activation, other than the primary Ras-binding site, the leucine-rich repeat domain. Here, we observed a posttranslational modification-dependent association of Ras with a complex between CAP and CYR1 C-terminal region. When CAP mutants defective in Ras signaling but retaining the CYR1-binding activity were isolated by screening of a pool of randomly mutagenized CAP, CYR1 complexed with two of the obtained three mutants failed to be activated efficiently by modified Ras and exhibited a severely impaired ability to bind Ras, providing a genetic evidence for the importance of the physical association with Ras at the second Ras-binding site. On the other hand, CYR1, complexed with the other CAP mutant, failed to be activated by Ras but exhibited a greatly enhanced binding to Ras. Conversely, a Ras mutant E31K, which exhibits a greatly enhanced binding to the CYR1-CAP complex, failed to activate CYR1 efficiently. Thus, the strength of interaction at the second Ras-binding site appears to be a critical determinant of CYR1 regulation by Ras: too-weak and too-strong interactions are both detrimental to CYR1 activation. These results, taken together with those obtained with mammalian Raf, suggest the importance of the second Ras-binding site in effector regulation.
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Affiliation(s)
- F Shima
- Department of Physiology II, Kobe University School of Medicine, Chuo-ku, Kobe 650-0017, Japan
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27
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Liao Y, Kariya K, Hu CD, Shibatohge M, Goshima M, Okada T, Watari Y, Gao X, Jin TG, Yamawaki-Kataoka Y, Kataoka T. RA-GEF, a novel Rap1A guanine nucleotide exchange factor containing a Ras/Rap1A-associating domain, is conserved between nematode and humans. J Biol Chem 1999; 274:37815-20. [PMID: 10608844 DOI: 10.1074/jbc.274.53.37815] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [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: 11/06/2022] Open
Abstract
A yeast two-hybrid screening for Ras-binding proteins in nematode Caenorhabditis elegans has identified a guanine nucleotide exchange factor (GEF) containing a Ras/Rap1A-associating (RA) domain, termed Ce-RA-GEF. Both Ce-RA-GEF and its human counterpart Hs-RA-GEF possessed a PSD-95/DlgA/ZO-1 (PDZ) domain and a Ras exchanger motif (REM) domain in addition to the RA and GEF domains. They also contained a region homologous to a cyclic nucleotide monophosphate-binding domain, which turned out to be incapable of binding cAMP or cGMP. Although the REM and GEF domains are conserved with other GEFs acting on Ras family small GTP-binding proteins, the RA and PDZ domains are unseen in any of them. Hs-RA-GEF exhibited not only a GTP-dependent binding activity to Rap1A at its RA domain but also an activity to stimulate GDP/GTP exchange of Rap1A both in vitro and in vivo at the segment containing its REM and GEF domains. However, it did not exhibit any binding or GEF activity toward Ras. On the other hand, Ce-RA-GEF associated with and stimulated GDP/GTP exchange of both Ras and Rap1A. These results indicate that Ce-RA-GEF and Hs-RA-GEF define a novel class of Rap1A GEF molecules, which are conserved through evolution.
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Affiliation(s)
- Y Liao
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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28
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Tanaka Y, Minami Y, Mine S, Hirano H, Hu CD, Fujimoto H, Fujii K, Saito K, Tsukada J, van Kooyk Y, Figdor CG, Kataoka T, Eto S. H-Ras signals to cytoskeletal machinery in induction of integrin-mediated adhesion of T cells. J Immunol 1999; 163:6209-16. [PMID: 10570313] [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
The adhesive function of integrins is regulated through cytoplasmic signaling. The present study was performed to investigate the relevance of cytoplasmic signaling and cytoskeletal assembly to integrin-mediated adhesion induced by chemokines. Adhesion of T cells induced by chemokines macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was inhibited by pertussis toxin, wortmannin, and cytochalasin B, suggesting that both G protein-sensitive phosphatidylinositol (PI) 3-kinase activation and cytoskeletal assemblies are involved. The chemokine-induced T cell adhesion could be mimicked by expression of small G proteins, fully activated H-RasV12, or H-RasV12Y40C mutant, which selectively binds to PI 3-kinase, in T cells, inducing activated form of LFA-1alpha and LFA-1-dependent adhesion to ICAM-1. H-Ras expression also induced F-actin polymerization which colocalized with profilin in T cells. Adult T cell leukemia (ATL) cells spontaneously adhered to ICAM-1, which depended on endogenous MIP-1alpha and MIP-1beta through activation of G protein-sensitive PI 3-kinase. H-Ras signal pathway, leading to PI 3-kinase activation, also induced active configuration of LFA-1 and LFA-1-mediated adhesion of ATL cells, whereas expression of a dominant-negative H-Ras mutant failed to do. Profilin-dependent spontaneous polymerization of F-actin in ATL cells was reduced by PI 3-kinase inhibitors. In this paper we propose that H-Ras-mediated activation of PI 3-kinase can be involved in induction of LFA-1-dependent adhesion of T cells, which is relevant to chemokine-mediated signaling, and that profilin may form an important link between chemokine- and/or H-Ras-mediated signals and F-actin polymerization, which results in triggering of LFA-1 on T cells or leukemic T cells.
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Affiliation(s)
- Y Tanaka
- First Department of Internal Medicine, University of Occupational and Environmental Health, Japan, School of Medicine, Kitakyushu, Japan.
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Okada T, Hu CD, Jin TG, Kariya K, Yamawaki-Kataoka Y, Kataoka T. The strength of interaction at the Raf cysteine-rich domain is a critical determinant of response of Raf to Ras family small GTPases. Mol Cell Biol 1999; 19:6057-64. [PMID: 10454553 PMCID: PMC84512 DOI: 10.1128/mcb.19.9.6057] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [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: 11/20/2022] Open
Abstract
To be fully activated at the plasma membrane, Raf-1 must establish two distinct modes of interactions with Ras, one through its Ras-binding domain and the other through its cysteine-rich domain (CRD). The Ras homologue Rap1A is incapable of activating Raf-1 and even antagonizes Ras-dependent activation of Raf-1. We proposed previously that this property of Rap1A may be attributable to its greatly enhanced interaction with Raf-1 CRD compared to Ras. On the other hand, B-Raf, another Raf family member, is activatable by both Ras and Rap1A. When interactions with Ras and Rap1A were measured, B-Raf CRD did not exhibit the enhanced interaction with Rap1A, suggesting that the strength of interaction at CRDs may account for the differential action of Rap1A on Raf-1 and B-Raf. The importance of the interaction at the CRD is further supported by a domain-shuffling experiment between Raf-1 and B-Raf, which clearly indicated that the nature of CRD determines the specificity of response to Rap1A: Raf-1, whose CRD is replaced by B-Raf CRD, became activatable by Rap1A, whereas B-Raf, whose CRD is replaced by Raf-1 CRD, lost its response to Rap1A. Finally, a B-Raf CRD mutant whose interaction with Rap1A is selectively enhanced was isolated and found to possess the double mutation K252E/M278T. B-Raf carrying this mutation was not activated by Rap1A but retained its response to Ras. These results indicate that the strength of interaction with Ras and Rap1A at its CRD may be a critical determinant of regulation of the Raf kinase activity by the Ras family small GTPases.
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Affiliation(s)
- T Okada
- Department of Physiology II, Kobe University School of Medicine, Chuo-ku, Kobe 650-0017, Japan
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Hu CD, Kariya K, Okada T, Qi X, Song C, Kataoka T. Effect of phosphorylation on activities of Rap1A to interact with Raf-1 and to suppress Ras-dependent Raf-1 activation. J Biol Chem 1999; 274:48-51. [PMID: 9867809 DOI: 10.1074/jbc.274.1.48] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [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: 11/06/2022] Open
Abstract
Rap1A is phosphorylated by cAMP-dependent protein kinase (PKA), and this phosphorylation has been shown to modulate its interaction with other proteins. However, it is not known whether Rap1A phosphorylation is involved in regulation of its cellular functions, including suppression of Ras-dependent Raf-1 activation. We have previously shown that this suppressive activity of Rap1A is attributable to its greatly enhanced ability to bind to the cysteine-rich region (CRR, residues 152-184) of Raf-1 compared with that of Ras. Here, we show that phosphorylation of Rap1A by PKA abolished its binding activity to CRR. Furthermore, a mutant Rap1A(S180E), whose sole PKA phosphorylation residue, Ser-180, was substituted by an acidic residue, Glu, to mimic its phosphorylated form, failed to suppress Ras-dependent Raf-1 activation in COS-7 cells. These results indicate that the CRR binding activity and the Ras-suppressive function of Rap1A can be modulated through phosphorylation and suggest that Rap1A may function as a PKA-dependent regulator of Raf-1 activation, not merely as a suppressor.
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Affiliation(s)
- C D Hu
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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Watari Y, Kariya K, Shibatohge M, Liao Y, Hu CD, Goshima M, Tamada M, Kikuchi A, Kataoka T. Identification of Ce-AF-6, a novel Caenorhabditis elegans protein, as a putative Ras effector. Gene 1998; 224:53-8. [PMID: 9931431 DOI: 10.1016/s0378-1119(98)00527-7] [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: 11/26/2022]
Abstract
Mammalian Ras proteins associate with multiple effectors, including Raf, Ral guanine nucleotide dissociation stimulator, phosphoinositide 3-kinase and AF-6. In the nematode Caenorhabditis elegans, LIN-45/Raf has been identified genetically as an effector of LET-60/Ras. To search for other effectors in C. elegans, we carried out a yeast two-hybrid screening for LET-60-associating proteins. The screening identified a novel protein, designated Ce-AF-6, which exhibited a strong structural homology with human AF-6, rat Afadin and Drosophila melanogaster Canoe and possessed both the Ras-associating (RA) domain and the PSD-95/DlgA/ZO-1 (PDZ) domain. Ce-AF-6 associated with human Ha-Ras in a GTP-dependent manner, with an efficiency comparable to that of human Raf-1 Ras-binding domain. When the effects of mutations of the Ras effector region residues were examined for associations with various effectors, Ce-AF-6 was found to possess a distinct and the most rigorous requirement for the effector region residues. These results strongly suggest that Ce-AF-6 is a putative effector of Ras that possesses a distinct recognition mechanism for association with Ras.
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Affiliation(s)
- Y Watari
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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Ohnishi M, Yamawaki-Kataoka Y, Kariya K, Tamada M, Hu CD, Kataoka T. Selective inhibition of Ras interaction with its particular effector by synthetic peptides corresponding to the Ras effector region. J Biol Chem 1998; 273:10210-5. [PMID: 9553071 DOI: 10.1074/jbc.273.17.10210] [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: 11/06/2022] Open
Abstract
Ras proteins possess multiple downstream effectors of distinct structures. We and others demonstrated that Ha-Ras carrying certain effector region mutations could interact differentially with its effectors, implying that significant differences exist in their Ras recognition mechanisms. Here, by employing the fluorescence polarization method, we measured the activity of effector region synthetic peptides bearing various amino acid substitutions to inhibit association of Ras with the effectors human Raf-1 and Schizosaccharomyces pombe Byr2. The effect of these peptides on association with another effector Saccharomyces cerevisiae adenylyl cyclase was also examined by measuring inhibition of the Ras-dependent adenylyl cyclase activity. The peptide corresponding to the residues 17-44 competitively inhibited Ras association with all the three effectors at the Ki values of 1 approximately 10 microM, and the inhibition was considerably attenuated by the D38A mutation. The peptide with the D38N mutation inhibited association of Ha-Ras with Byr2 but not with the others, whereas that with the P34G mutation inhibited association of Ha-Ras with Raf-1 and Byr2 but not with adenylyl cyclase. Thus, the specificity observed with the whole Ras protein was retained in the effector region peptide. These results suggest that the effector region residues constitute a major determinant for differential recognition of the effector molecules, raising a possibility for selective inhibition of a particular Ras function.
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Affiliation(s)
- M Ohnishi
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650, Japan
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Shirouzu M, Morinaka K, Koyama S, Hu CD, Hori-Tamura N, Okada T, Kariya K, Kataoka T, Kikuchi A, Yokoyama S. Interactions of the amino acid residue at position 31 of the c-Ha-Ras protein with Raf-1 and RalGDS. J Biol Chem 1998; 273:7737-42. [PMID: 9516482 DOI: 10.1074/jbc.273.13.7737] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ras and Rap1A proteins can bind to the Raf and RalGDS families. Ras and Rap1A have Glu and Lys, respectively, at position 31. In the present study, we analyzed the effects of mutating the Glu at position 31 of the c-Ha-Ras protein to Asp, Ala, Arg, and Lys on the interactions with Raf-1 and RalGDS. The Ras-binding domain (RBD) of Raf-1 binds the E31R and E31K Ras mutants less tightly than the wild-type, E31A, and E31D Ras proteins; the introduction of the positively charged Lys or Arg residue at position 31 specifically impairs the binding of Ras with the Raf-1 RBD. On the other hand, the ability of the oncogenic RasG12V protein to activate Raf-1 in HEK293 cells was only partially reduced by the E31R mutation but was drastically impaired by the E31K mutation. Correspondingly, RasG12V(E31K) as well as Rap1A, but not RasG12V(E31R), exhibited abnormally tight binding with the cysteine-rich domain of Raf-1. On the other hand, the E31A, E31R, and E31K mutations, but not the E31D mutation, enhanced the RalGDS RBD-binding activity of Ras, indicating that the negative charge at position 31 of Ras is particularly unfavorable to the interaction with the RalGDS RBD. RasG12V(E31K), RasG12V(E31A), and Rap1A stimulate the RalGDS action more efficiently than the wild-type Ras in the liposome reconstitution assay. All of these results clearly show that the sharp contrast between the characteristics of Ras and Rap1A, with respect to the interactions with Raf-1 and RalGDS, depends on their residues at position 31.
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Affiliation(s)
- M Shirouzu
- Cellular Signaling Laboratory, Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi, Saitama 351-01, Japan
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Shibatohge M, Kariya KI, Liao Y, Hu CD, Watari Y, Goshima M, Shima F, Kataoka T. Identification of PLC210, a Caenorhabditis elegans phospholipase C, as a putative effector of Ras. J Biol Chem 1998; 273:6218-22. [PMID: 9497345 DOI: 10.1074/jbc.273.11.6218] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [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: 11/06/2022] Open
Abstract
Mammalian Ras proteins regulate multiple effectors including Raf, Ral guanine nucleotide dissociation stimulator (RalGDS), and phosphoinositide 3-kinase. In the nematode Caenorhabditis elegans, LIN-45 Raf has been identified by genetic analyses as an effector of LET-60 Ras. To search for other effectors in C. elegans, we performed a yeast two-hybrid screening for LET-60-binding proteins. The screening identified two cDNA clones encoding a phosphoinositide-specific phospholipase C (PI-PLC) with a predicted molecular mass of 210 kDa, designated PLC210. PLC210 possesses two additional functional domains unseen in any known PI-PLCs. One is the C-terminal Ras-associating domain bearing a structural homology with those of RalGDS and AF-6. This domain, which could be narrowed down to 100 amino acid residues, associated in vitro with human Ha-Ras in a GTP-dependent manner and competed with yeast adenylyl cyclase for binding Ha-Ras. The binding was abolished by specific mutations within the effector region of Ha-Ras. The other functional domain is the N-terminal CDC25-like domain, which possesses a structural homology to guanine nucleotide exchange proteins for Ras. These results strongly suggest that PLC210 belongs to a novel class of PI-PLC, which is a putative effector of Ras.
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Affiliation(s)
- M Shibatohge
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650, Japan
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Abstract
Ras interacts with Raf-1 and stimulates its kinase activity, which results in activation of the mitogen-activated protein (MAP) kinase cascade. It has been proposed that the main function of Ras in Raf-1 activation is to recruit Raf-1 to the plasma membrane, where a separate activation event such as phosphorylation takes place. Here, we examined the activities of various mutants of human Ha-Ras to induce membrane translocation of Raf-1 and to activate Raf-1 in vivo. Overexpression of an activator region mutant Ha-Ras(V45E) in COS7 cells induced membrane translocation of Raf-1 as effectively as wild-type Ha-Ras. However, the activity of this mutant to activate Raf-1 and extracellular signal-regulated kinase-2 (ERK2) was attenuated by approximately 70% compared to that of wild-type Ha-Ras. The decrease in the specific activity was further demonstrated by measuring the activity of the Ha-Ras(V45E)-associated Raf-1 purified from the membrane fraction. These results imply that the association of Ras with Raf-1 has another important consequence, presumably dependent on the interaction between its activator region and Raf-1, than the simple recruitment of Raf-1 to the plasma membrane.
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Affiliation(s)
- M Tamada
- Department of Physiology II, Kobe University School of Medicine, Japan
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Hu CD, Kariya KI, Kotani G, Shirouzu M, Yokoyama S, Kataoka T. Coassociation of Rap1A and Ha-Ras with Raf-1 N-terminal region interferes with ras-dependent activation of Raf-1. J Biol Chem 1997; 272:11702-5. [PMID: 9115221 DOI: 10.1074/jbc.272.18.11702] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [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: 02/04/2023] Open
Abstract
Raf-1 is a major downstream effector of mammalian Ras. Binding of the effector domain of Ras to the Ras-binding domain of Raf-1 is essential for Ras-dependent Raf-1 activation. However, Rap1A, which has an identical effector domain to that of Ras, cannot activate Raf-1 and even antagonizes several Ras functions in vivo. Recently, we identified the cysteine-rich region (CRR) of Raf-1 as another Ras-binding domain. Ha-Ras proteins carrying mutations N26G and V45E, which failed to bind to CRR, also failed to activate Raf-1. Since these mutations replace Ras residues with those of Rap1A, we examined if Rap1A lacks the ability to bind to CRR. Contrary to the expectation, Rap1A exhibited a greatly enhanced binding to CRR compared with Ha-Ras. Enhanced CRR binding was also found with Ha-Ras carrying another Rap1A-type mutation E31K. Both Rap1A and Ha-Ras(E31K) mutant failed to activate Raf-1 and interfered with Ha-Ras-dependent activation of Raf-1 in Sf9 cells. Enhanced binding of Rap1A to CRR led to co-association of Rap1A and Ha-Ras with Raf-1 N-terminal region through binding to CRR and Ras-binding domain, respectively. These results suggest that Rap1A interferes with Ras-dependent Raf-1 activation by inhibiting binding of Ras to Raf-1 CRR.
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Affiliation(s)
- C D Hu
- Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650, Japan
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Yanagihara C, Shinkai M, Kariya K, Yamawaki-Kataoka Y, Hu CD, Masuda T, Kataoka T. Association of elongation factor 1 alpha and ribosomal protein L3 with the proline-rich region of yeast adenylyl cyclase-associated protein CAP. Biochem Biophys Res Commun 1997; 232:503-7. [PMID: 9125210 DOI: 10.1006/bbrc.1997.6326] [Citation(s) in RCA: 10] [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
CAP is a multifunctional protein; the N-terminal region binds adenylyl cyclase and controls its response to Ras while the C-terminal region is involved in cytoskeletal regulation. In between the two regions, CAP possesses two proline-rich segments, P1 and P2, resembling a consensus sequence for binding SH3 domains. We have identified two yeast proteins with molecular sizes of 48 and 46 kDa associated specifically with P2. Determination of partial protein sequences demonstrated that the 48-kDa and 46-kDa proteins correspond to EF1 alpha and rL3, respectively, neither of which contains any SH3-domain-like sequence. Deletion of P2 from CAP resulted in loss of the activity to bind the two proteins either in vivo or in vitro. Yeast cells whose chromosomal CAP was replaced by the P2-deletion mutant displayed an abnormal phenotype represented by dissociated localizations of CAP and F-actin, which were colocalized in wild-type cells. These results suggest that these associations may have functional significance.
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Affiliation(s)
- C Yanagihara
- Department of Physiology II, Kobe University School of Medicine, Japan
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Hu CD, Kariya K, Tamada M, Akasaka K, Shirouzu M, Yokoyama S, Kataoka T. Cysteine-rich region of Raf-1 interacts with activator domain of post-translationally modified Ha-Ras. J Biol Chem 1995; 270:30274-7. [PMID: 8530446 DOI: 10.1074/jbc.270.51.30274] [Citation(s) in RCA: 114] [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: 01/31/2023] Open
Abstract
The interaction between "switch I/effector domain" of Ha-Ras and the Ras-binding domain (RBD, amino acid 51-131) of Raf-1 is essential for signal transduction. However, the importance of the "activator domain" (approximately corresponding to amino acids 26-28 and 40-49) of Ha-Ras and of the "cysteine-rich region" (CRR, amino acids 152-184) of Raf-1 have also been proposed. Here, we found that Raf-1 CRR interacts directly with Ha-Ras independently of RBD and that participation of CRR is necessary for efficient Ras-Raf binding. Furthermore, Ha-Ras carrying mutations (N26G and V45E) in the activator domain failed to bind CRR, whereas they bound RBD normally. On the contrary, Ha-Ras carrying mutations in the switch I/effector domain exhibited severely reduced ability to bind RBD, whereas their ability to bind CRR was unaffected. Mutants that bound to either RBD or CRR alone failed to activate Raf-1. Ha-Ras without post-translational modifications, which lacks the ability to activate Raf-1, selectively lost the ability to bind CRR. These results suggest that the activator domain of Ha-Ras participates in activation of Raf-1 through interaction with CRR and that post-translational modifications of Ha-Ras are required for this interaction.
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Affiliation(s)
- C D Hu
- Department of Physiology II, Kobe University School of Medicine, Japan
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Hu CD. Second-harmonic generation on simple metal surfaces excited by p-polarized light: The volume current. Phys Rev B Condens Matter 1993; 47:7525-7536. [PMID: 10004747 DOI: 10.1103/physrevb.47.7525] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Hu CD. Second-harmonic generation on simple metal surfaces: A quantum-mechanical point of view. Phys Rev B Condens Matter 1989; 40:7520-7526. [PMID: 9991176 DOI: 10.1103/physrevb.40.7520] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Hu CD, Chang Y. Polaron Zeeman effect in GaAs/AlxGa1-xAs multiple-quantum-well structures. Phys Rev B Condens Matter 1989; 40:3878-3881. [PMID: 9992358 DOI: 10.1103/physrevb.40.3878] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Hu CD, Langreth DC. Beyond the random-phase approximation in nonlocal-density-functional theory. Phys Rev B Condens Matter 1986; 33:943-959. [PMID: 9938357 DOI: 10.1103/physrevb.33.943] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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