Zhang J.-F.,Xiamen University |
Zhang J.-F.,Tongren University |
Lu J.-F.,Xiamen University
Astrophysical Journal | Year: 2015
In order to understand the main observational characteristics of the Galactic X-ray binary Cygnus X-3, we propose a radiation model in which high-energy electrons accelerate in the dissipation zone of a jet and produce nonthermal broadband emissions. Broadband spectral energy distributions are computed to compare the AGILE and Fermi LAT data with the multi-band data during soft X-ray spectral states. By fitting observations at different locations of the jet, we find that the emission region is rather compact and should be located at a distance of about one orbital radius. Our results can explain the current multi-frequency observations and also predict the TeV band emission. The model could be tested by a polarization measurement at IR band, and/or by a correlation study between the GeV and TeV bands once very-high-energy observations are available. © 2015. The American Astronomical Society. All rights reserved.
Zhang J.,Xiamen University |
Zhang J.,Tongren University |
Xu B.,Tongren University |
Lu J.,Xiamen University
Astrophysical Journal | Year: 2014
We study the origin of non-thermal emissions from the Galactic black hole X-ray binary Cygnus X-1, which is a confirmed high-mass microquasar. By analogy with the methods used in studies of active galactic nuclei, we propose a two-dimensional, time-dependent radiation model from the microquasar Cygnus X-1. In this model, the evolution equation for relativistic electrons in a conical jet are numerically solved by including escape, adiabatic, and various radiative losses. The radiative processes involved are synchrotron emission, its self-Compton scattering, and inverse Compton scatterings of an accretion disk and its surrounding stellar companion. This model also includes an electromagnetic cascade process of an anisotropic γ-γ interaction. We study the spectral properties of electron evolution and its emission spectral characteristic at different heights of the emission region located in the jet. We find that radio data from Cygnus X-1 are reproduced by the synchrotron emission, the Fermi Large Area Telescope measurements by the synchrotron emission and Comptonization of photons of the stellar companion, and the TeV band emission fluxes by the Comptonization of the stellar photons. Our results show the following. (1) The radio emission region extends from the binary system scales to the termination of the jet. (2) The GeV band emissions should originate from the distance close to the binary system scales. (3) The TeV band emissions could be inside the binary system, and these emissions could be probed by the upcoming Cherenkov Telescope Array. (4) The MeV tail emissions, which produce a strongly linearly polarized signal, are emitted inside the binary system. The location of the emissions is very close to the inner region of the jet. © 2014. The American Astronomical Society. All rights reserved..
She Y.,Xiangtan University |
Zheng X.,Xiangtan University |
Wang D.,Xiangtan University |
Zhang W.,Tongren University
Optics Express | Year: 2013
We consider the coupling effect between interdot tunneling coupling and external optical control field to study the linear optical property and the formation of temporal optical solitons in a quantum dot molecules system, analytically. The results show that the double tunneling induced transparency (TIT) windows are appeared in the absorption curve of probe field because of the formation of dynamic Stark splitting and quantum destructive interference effect from the two upper levels. Interestingly, the width of the TIT window becomes wider with the increasing intensity of the optical control field. We also find that the Kerr nonlinear effect of the probe field can be modulated effectively through coherent control both the control field and the interdot tunneling coupling in this system. Meanwhile, we demonstrate that the formation of dark or bright solitons can be practical regulated by varying the intensity of the optical control field. © 2013 Optical Society of America.
Li Z.,Tongren University |
Wang X.,Tongren University |
Chi B.,Huazhong University of Science and Technology
RSC Advances | Year: 2014
First principles density functional theory calculations were carried out to investigate the adsorption and reaction of N2O and CO on the modified N + Fe/TiO2 (101) surface (M-S(101)) of anatase. The adsorption energies of N2O on M-S(101) and CO/M-S(101) were obtained. The mechanisms of the conversion of CO and N2O to CO2 and N2 were proposed and the photocatalytic involvement was described. The calculations indicated that the process described here happened only on doped Fe atoms and the possibility of a photocatalytic cycle was discussed assuming electron scavenging by the codoping of Fe and N atoms. This journal is © the Partner Organisations 2014.
Zhang J.-F.,Tongren University |
Xie F.-G.,Chinese Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2013
Under the framework of the magnetized accretion ejection structures, we analyse the energy balance properties, and study the spectral energy distributions (SEDs) of the jet-emitting disc (JED) model for black hole X-ray transients. Various radiative processes are considered, i.e. synchrotron, bremsstrahlung, and their Comptonizations, and external Comptonization of radiation from the outer thin disc. With these cooling terms taken into account, we solve the thermal equilibrium equation self-consistently and find three solutions, of which the cold and the hot solutions are stable. Subsequently, we investigate the theoretical SEDs for these two stable solutions. We find the hot JED model can naturally explain the spectra of the Galactic microquasars in their hard states. As an example, we apply this model to the case of XTE J1118+480. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Chen H.,Shanghai Nanotechnology Promotion Center |
Leng S.,Tongren University
Ceramics International | Year: 2015
Hollow nano-structured hydroxyapatite [Ca10(PO4)6(OH)2, HAp] microspheres were rapidly synthesized via microwave transformation of a sacrificial hard-template of similarly structured calcium carbonate (CaCO3) hollow microspheres in Na3PO4 aqueous solution. Results showed that the microwave process significantly increased transformation efficiency. Pure hollow HAp microspheres could be obtained within ultra-short-period of 30 min via the microwave transformation process, in comparison to over 48 h in the traditional hydrothermal transformation method. These studies suggest that the microwave assisted hard-template transformation process is an effective approach to synthesize HAp with high efficiency. The resulting hollow nano-structured HAp microspheres may have applications in drug-delivery and serve as materials for chemical and environmental applications. © 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Zhang J.F.,Tongren University |
Feng Y.G.,Tongren University
Monthly Notices of the Royal Astronomical Society | Year: 2011
We propose a model to account for the non-thermal radiation due to the interaction of the jet termination shock of a microquasar (MQ) with its ambient interstellar medium (ISM). In this model, relativistic electrons and protons are accelerated simultaneously in the jet termination reverse shock. These particles then diffuse into the ISM from a region shocked by the reverse shock and interact with another region shocked by the forward shock, which can produce detectable photon fluxes at different energies. Using numerical calculation, we present various photon spectra for a general MQ produced via synchrotron, inverse Compton, synchrotron self-Compton, relativistic bremsstrahlung and π 0-decay emissions. Finally, we apply this model to the MQ Cygnus X-1 by modifying various parameters. Our results show the extent of radiative emission from the ISM-jet interaction region, which may be detectable by the current Fermi Large Area Telescope and the future Cherenkov Telescope Array. © 2010 The Authors. Journal compilation © 2010 RAS.
Song M.S.,Tongren University |
Ran M.W.,Tongren University |
Kong Y.Y.,Tongren University
International Journal of Refractory Metals and Hard Materials | Year: 2011
The in situ synthesis of ZrC powder utilizing self-propagating high-temperature synthesis (SHS) reaction that occurred in the compact consisting of Al, Zr and C powders was investigated. The result shows when Al contents were 0-40 wt.% SHS reaction proceeded favorably. The as-products display a uniform distribution of ZrC particles with the sizes ranging from 8 μm at Al free to 50 nm at 40 wt.% Al. The temperature curve, coupled with the quenched treatment, indicates that the Al-Zr reaction to form ZrAl3 initiated and then C reacted with ZrAl3 to form the more stable ZrC phase. It also proves that the mechanism of reaction-precipitation should be responsible for the formation of ZrC in this system. Al has been playing an important role in determining the formation of ZrC, not only as a diluent to inhibit the ZrC grains from coarsening, but also as an intermediate reactant to participate in the total reaction. © 2011 Elsevier Ltd. All rights reserved.
Liu H.,Tongren University
Applied Mechanics and Materials | Year: 2014
With the rapid development of computer technology and network, computer, as an assistant means of teaching, finds a broad use of foreign language instruction. In particular, it is worth mentioning that computer assisted language learning (CALL), as a newly booming science, plays an increasingly important role in language teaching and learning and has become an important solution to the current education problems encountered in the process. However, CALL can only play a supporting role in foreign language teaching. In the foreign language teaching with CALL, it is proper to develop the advantages of advanced technology, and meanwhile to deny the traditional teaching mode and inappropriate teaching methods. Therefore, combined with the reality, this paper makes an argument that in the process of teaching, we must keep in the reasonable application of CALL to avoid the negative effects of abusing it while actively and prudently promote the reform of college English to cultivate interdisciplinary talents in the new century. © (2014) Trans Tech Publications, Switzerland.
Wu S.-Z.,South China University of Technology |
Wu S.-Z.,Tongren University |
Li K.,South China University of Technology |
Zhang W.-D.,South China University of Technology
Applied Surface Science | Year: 2015
Heterostructured photocatalysts Ag3VO4/g-C3N4 were prepared by deposition-precipitation method in order to anchor Ag3VO4 on the surface of N-vacancy g-C3N4 (g-C3N4-VN). The photocatalytic activity of the samples was evaluated by degrading rhodamine B (RhB) in aqueous solution. Compared with the pure Ag3VO4 and g-C3N4-VN, the heterojuncted photocatalyst 65 wt% Ag3VO4/g-C3N4-VN exhibits the best activity under visible light irradiation. The photodegradation rate constant of 65 wt% Ag3VO4/g-C3N4-VN is 0.0556 min-1, which is 23.4, 5.8 and 6.4 times of that of pure Ag3VO4, pure g-C3N4-VN and P25, respectively. The excellent photocatalytic performance of the Ag3VO4/g-C3N4-VN catalysts can be ascribed to the matched band structures of Ag3VO4 and g-C3N4, which strengthened the formation of the heterojuncted photocatalyst. The unique heterostructured photocatalyst is favorable for retarding the recombination of photogenerated electrons and holes, thus the photocatalytic activity is significantly increased. Further experiment also reveals that the •O2 - and h+ are the major active species in the degradation of RhB. © 2014 Elsevier B.V. All rights reserved.