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Mode Change of a Gamma-Ray Pulsar, PSR J2021+4026
Zhao, J.,Ng, C. W.,Lin, L. C. C.,Takata, J.,Cai, Y.,Hu, C.-P.,Yen, D. C. C.,Tam, P. H. T.,Hui, C. Y.,Kong, A. K. H.,Cheng, K. S. American Astronomical Society 2017 The Astrophysical journal Vol.842 No.1
<P>A glitch of a pulsar is known as a sudden increase in the spin frequency and spin-down rate (frequency time derivative), and it can be caused by a sudden release of the stress built up in the solid crust of the star or pinned vortices in the superfluid interior. PSR J2021+4026 is the first pulsar that shows a significant change in the gamma-ray flux and pulse profile at the glitch that occurred around 2011 October 16. We report the results of timing and spectral analysis of PSR J2021+4026 using similar to 8 yr Fermi. Large Area Telescope data. We find that the pulsar stayed at a high spin-down rate (similar to 4% higher than the pre-glitch value) and a low gamma-ray state (similar to 18% lower) for about 3 yr. after the glitch. Around 2014 December, the spin-down rate and gamma-ray flux gradually returned to pre-glitch values within a timescale of a. few months. The phase-resolved spectra and pulse profiles after the relaxation are also consistent with those before the glitch. The observed long-term evolution of the spin-down rate and the gamma-ray flux indicates that the glitch triggered a mode change in the global magnetosphere. We speculate that the glitch changed. the local magnetic field structure around the polar cap and/or the inclination angle of the. dipole axis, leading to. a change in the electric current circulating in the. magnetosphere.</P>
Zhao, K.J.,Nagashima, Y.,Li, F.M.,Shi, Yuejiang,Diamond, P.H.,Dong, J.Q.,Itoh, K.,Itoh, S.-I.,Zhuang, G.,Liu, H.,Chen, Z.P.,Cheng, J.,Nie, L.,Ding, Y.H.,Hu, Q.M.,Chen, Z.Y.,Rao, B.,Cheng, Z.F.,Gao, L. IOP 2017 Nuclear fusion Vol.57 No.12
<P>The temporal-spatial structures of plasma flows and turbulence around tearing mode islands are presented. The experiments were performed using Langmuir probe arrays in the edge plasmas of J-TEXT tokamak. The correlation analyses clearly show that the flows have similar structures of <I>m</I>/<I>n</I> = 3/1 as the magnetic island does (<I>m</I> and <I>n</I> are the poloidal and toroidal mode numbers, respectively). The sign of the potential fluctuations for the flows inverses and the powers significantly reduce at <I>q</I> = 3 surface. Approaching to the last closed flux surface for the magnetic islands, the radially elongated flow structure forms. The flows are concentrated near separatrix and show quadrupole structures. The turbulence is concentrated near X-point and partly trapped inside the magnetic islands.</P>
THE MEGAMASER COSMOLOGY PROJECT. IX. BLACK HOLE MASSES FOR THREE MASER GALAXIES
Gao, F.,Braatz, J. A.,Reid, M. J.,Condon, J. J.,Greene, J. E.,Henkel, C.,Impellizzeri, C. M. V.,Lo, K. Y.,Kuo, C. Y.,Pesce, D. W.,Wagner, J.,Zhao, W. American Astronomical Society 2017 The Astrophysical journal Vol.834 No.1
<P>As part of the Megamaser Cosmology Project, we present VLBI maps of nuclear water masers toward five galaxies. The masers originate in sub-parsec circumnuclear disks. For three of the galaxies, we fit Keplerian rotation curves to estimate their supermassive black hole (SMBH) masses, and determine (2.9 +/- 0.3) x 10(6)M(Theta) for J0437+2456, (1.7 +/- 0.1) x 10(7)M(Theta) for ESO 558-G009, and (1.1 +/- 0.2) x 10(7)M(Theta) for NGC 5495. In the other two galaxies, Mrk 1029 and NGC 1320, the geometry and dynamics are more complicated and preclude robust black hole mass estimates. Including our new results, we compiled a list of 15 VLBI-confirmed disk maser galaxies with robust SMBH mass measurements. With this sample, we confirm the empirical relation of R-out proportional to 0.3M(SMBH) reported in Wardle & Yusef-Zadeh. We also find a tentative correlation between maser disk outer radii and Wide-Field Infrared Survey Explorer luminosity. We find no correlations of maser disk size with X-ray 2-10 keV luminosity or [O III] luminosity.</P>
Thermoelectric properties of Gd, Y co-doped Ca3Co4O9+δ
H.Q. Liu,X.B. Zhao,T.J. Zhu,Y. Song,F.P. Wang 한국물리학회 2009 Current Applied Physics Vol.9 No.3
The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ. The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ.
Ranot, M.,Seong, W.K.,Jung, S.G.,Lee, N.H.,Kang, W.N.,Joo, J.H.,Zhao, Y.,Dou, S.X. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15
We report on Ag and Cu doping in MgB<SUB>2</SUB> thick films using amorphous Ag- and Cu-impurity layers with various thicknesses, 4, 8, 16, and 32nm. Firstly, Ag- and Cu-impurity layers were deposited on Al<SUB>2</SUB>O<SUB>3</SUB>(0001) substrates at room temperature by using pulsed laser deposition system. Subsequently MgB<SUB>2</SUB> films were grown on the top of Ag or Cu/Al<SUB>2</SUB>O<SUB>3</SUB> substrates at 560 and 600<SUP>o</SUP>C by using hybrid physical-chemical vapor deposition. The effect of Ag and Cu doping as well as growth temperature on the microstructure and critical current density (J<SUB>c</SUB>) of MgB<SUB>2</SUB> films were investigated. It was found that both of Ag/Cu doping and low growth temperature can significantly enhance J<SUB>c</SUB> without suppression of T<SUB>c</SUB>. The increase in J<SUB>c</SUB> results from improved grain connectivity and strong flux pinning by high density of grain boundaries and other types of defects introduced by Ag- or Cu-impurity layers.
Zhao, Z.L.,Kim, S.C.,Zhang, J.,Liu, H.F.,Lee, B.H.,Jang, E.Y.,Lee, C.W.,Cho, I.J.,An, W.G.,Yang, C.H.,Kim, Y.W.,Zhao, R.J.,Wu, Y.Y. Elsevier Science B.V., Amsterdam 2016 JOURNAL OF ACUPUNCTURE AND MERIDIAN STUDIES Vol.9 No.1
A previous study demonstrated that acupuncture at ST36 (Zu-San-Li) attenuates ethanol withdrawal (EW)-induced hyperactivation of the hypothalamic-pituitary-adrenal axis in rats. The current study investigated the involvement of hypothalamic norepinephrine (NE) in that process. Rats were intraperitoneally treated with 3 g/kg/d of ethanol or saline for 28 days. After 24 hours of EW, acupuncture was applied to rats at bilateral ST36 points or at nonacupoints (tail) for 1 minute. A high-performance liquid chromatography analysis showed that EW significantly increased both the NE and the 3-methoxy-4-hydroxy-phenylglycol (MHPG) levels in the hypothalamic paraventricular nucleus (PVN). Western blot analysis also revealed that EW markedly elevated the phosphorylation rates of tyrosine hydroxylase (TH), but spared TH protein expression in the PVN. However, acupuncture at ST36, but not at nonacupoints, greatly inhibited the increase in the hypothalamic NE, MHPG, and phosphorylation rates of TH. Additionally, postacupuncture infusion of NE into the PVN significantly attenuated the inhibitory effects of acupuncture at ST36 on the oversecretion of plasma corticosterone during EW. These results suggest that acupuncture at ST36 inhibits EW-induced hyperactivation of the hypothalamic NEergic system to produce therapeutic effects on the hypothalamic-pituitary-adrenal axis.
Y.C. Li,M.H. Li,M. Wang,L. Liu,X.J. Zhang,C.M. Qin,Y.F. Wang,C.B. Wu,L.N. Liu,J.C. Xu,B. J. Ding,X. D. Lin,B. J. Ding,X. D. Lin,J. F. Shan,F. K. Liu,Y. P. Zhao,T. Zhang,X. Gao 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1
The suppression of high-intensity blob structures in the scrape-off layer (SOL) by ion-cyclotron range offrequencies (ICRF) power, leading to a decrease in the turbulent fluctuation level, is observed first in theExperimental Advanced Superconducting Tokamak (EAST) experiment. This suppression effect from ICRFpower injection is global in the whole SOL at EAST, i.e. blob structures both in the regions that aremagnetically connected to the active ICRF launcher and in the regions that are not connected to theactive ICRF launcher could be suppressed by ICRF power. However, more ICRF power is required to reachthe full blob structure suppression effect in the regions that are magnetically unconnected to the activelauncher than in the regions that are magnetically connected to the active launcher. Studies show that apossible reason for the blob suppression could be the enhanced Er B shear flow in the SOL, which issupported by the shaper radial gradient in the floating potential profiles sensed by the divertor probearrays with increasing ICRF power. The local RF wave power unabsorbed by the core plasma isresponsible for the modification of potential profiles in the SOL regions.
Dependence of the properties of hydrothermally grown ZnO on precursor concentration
Zhao, X.,Lee, J.Y.,Kim, C.-R.,Heo, J.,Shin, C.M.,Leem, J.-Y.,Ryu, H.,Chang, J.-H.,Lee, H.C.,Jung, W.-G.,Son, C.-S.,Shin, B.C.,Lee, W.-J.,Tan, S.T.,Zhao, J.,Sun, X. North-Holland 2009 Physica E, Low-dimensional systems & nanostructure Vol.41 No.8
This study evaluated the effects of precursor concentration ranging from 0.06 to 1.5M on the properties of hydrothermally grown ZnO on annealed ZnO buffered Si substrates. At relatively low concentrations (no more than 0.5M), well-aligned ZnO arrays were grown on ZnO/Si(100) due to heterogeneous nucleation. As the concentration was increased to 1.0M, the morphologies changed to randomly accumulated particles as a result of homogeneous nucleation. The crystal and optical properties of the materials were investigated by X-ray diffractometer (XRD) and photoluminescence (PL) measurement, respectively. It was found that the best crystal and optical properties were obtained with concentrations of 0.5 and 0.3M, respectively. These properties were observed to degrade when the concentration was raised to more than 1.0M.
Effects of Buffer Layer Annealing on ZnO Thin Films Grown by using Atomic Layer Deposition
J. Y. Leem,C. R. Kim,J. H. Heo,C. M. Shin,J. H. Park,T. M. Lee,류혁현,J. H. Chang,C. S. Son,B. C. Shin,W. J. Lee,S. T. Tan,J. L. Zhao,X. W. Sun 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6
In this study, the effects of buffer layer annealing duration on ZnO thin films deposited by using the remote plasma atomic layer deposition (ALD) method are discussed. ZnO thin films were grown on ZnO-buffer/Si (100) and were annealed for various durations between 0.5 and 60 min. The structural and the optical properties of the ZnO thin films were investigated by using atomic force microscopy, X-ray diffraction, and photoluminescence measurements. The ZnO thin films grown on a rough ZnO buffer layer were found to have high optical quality. The results from this study possibly contribute to advances in ZnO-base LED technologies.