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X-ray Flashes from Off-axis Nonuniform Jets

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Chinese Journal of Astronomy and Astrophysics 2004年第5期4卷 473-480页

作者： zhi-ping Jin Da-Ming Wei Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008 National Astronomical Observatories Chinese Academy of SciencesBeijing 100012

It has been widely believed that the outflows in gamma-ray bursts are jetted and some jets may have structures like ∈(θ)∝θ-k. We check the possibility that X-ray flashes come from such jets. Both qualitative and quantitative analyses have shown that this model can reproduce most of the observational features of both X-ray flashes and gamma-ray bursts. Using the usual parameters of gamma-ray bursts, we have carried out numerical calculations for both uniform and nonuniform jets, of their fluxes, spectra and peak energies. It seems that nonuniform jets are more appropriate to these observational properties than uniform jets. We have also shown that in our model the observational ratio of gamma-ray bursts to X-ray flashes is about a few units.

关键词： X-rays general-gamma rays bursts-ISM jets and outflows

Changing Rules of Bonding Electron Pair Correlation Energies of CH_3X (X=F,OH,NH_2) Systems

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Chinese Journal of Structural Chemistry 2004年第5期23卷 525-531页

作者： ZHUOShu-ping SIWei-Jiang JUGuan-zhi SchoolofChemicalEngineering ShandongUniversityofTechnologyZiboShandong255049China StateKeyLaboratoryofCoordinationChemistry DepartmentofChemistryNanjingUniversityNanjingJiangsu210093China

The pair correlation energy of bonding electrons is used and analyzed in the cal- culation of CH and CY (Y = F, O, N) bonding electron pairs in CH3X (X = F, OH, NH2) isoelec- tronic systems based on intra- and interpair correlation energy results at both MP2-OPT2/6- 311++G(d) and MP2-OPT2/cc-pVtz levels with MELD program. Comparison of two set results shows that cc-pVtz and 6-311++G(d) give more correlation energy of valence electrons and innermost core electron pairs, respectively in these systems, resulting that the total correlation energy with cc-pVtz basis of each system is larger than that with 6-311++G(d). Investigations of pair correlation energy show that with the decrease of electronegativity of X atom and the increase of H atoms in these CH3X (X = F, OH, NH2) systems, the pair correlation energy of 1sC2 of the C atoms is transferable, and the correlation energy of CH bonding electron pair with little changes is of approximate transferability, while those of CY (CF, CO, CN) bonding electron pair decrease in a large extent from CH3F through CH3OH to CH3NH2 molecules. It is suggested that the study of pair correlation energy of bonding electrons will further deepen the understanding of electron corre- lation effect from traditional chemical bonding concept.

关键词： pair correlation energy bonding electron pair CH3X systems

Collision site effect on the radiation dynamics of cytosine induced by proton

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Chinese Physics B 2022年第6期31卷 316-325页

作者： xu Wang zhi-ping Wang Feng-Shou Zhang Chao-Yi Qian Department of Fundamental Courses Wuxi Institute of TechnologyWuxi 214121China The Key Laboratory of Beam Technology and Material Modification of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China

By combing the time-dependent density functional calculations for electrons with molecular dynamics simulations for ions(TDDFT-MD)nonadiabatically in real time,we investigate the microscopic mechanism of collisions between cytosine and low-energy protons with incident energy ranging from 150 e V to 1000 e *** explore the effects of the collision site and the proton incident energy on irradiation processes of cytosine,two collision sites are specially considered,which are N and O both acting as the proton receptors when forming hydrogen bonds with *** only the energy loss and the scattering angle of the projectile but also the electronic and ionic degrees of freedom of the target are *** is found that the energy loss of proton increases linearly with the increase of the incident energy in both situations,which are14.2%and 21.1%of the incident energy ***,the scattering angles show different behaviors in these two situations when the incident kinetic energy *** proton collides with O,the scattering angle of proton is larger and the energy lost is more,while proton captures less electrons from *** calculated fragment mass distribution shows the high counts of the fragment mass of 1,implying the production of H+fragment ion from cytosine even for proton with the incident energy lower than ***,the calculated results show that N on cytosine is easier to be combined with low-energy protons to form NH bonds than O.

关键词： time-dependent density functional theory cytosine proton-induced collision fragmentation

Exact mobility edges and topological phase transition in two-dimensional non-Hermitian quasicrystals

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Science China(Physics,Mechanics & Astronomy) 2022年第2期65卷 82-90页

作者： zhi-Hao xu xu Xia Shu Chen Institute of Theoretical Physics and State Key Laboratory of Quantum Optics and Quantum Optics Devices Shanxi UniversityTaiyuan 030006China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Chern Institute of Mathematics and LPMC Nankai UniversityTianjin 300071China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Yangtze River Delta Physics Research Center Liyang 213300China

The emergence of the mobility edge(ME)has been recognized as an important characteristic of Anderson *** difficulty in understanding the physics of the MEs in three-dimensional(3 D)systems from a microscopic image encourages the development of models in lower-dimensional systems that have exact *** most of the previous studies are concerned with one-dimensional(1 D)quasiperiodic systems,the analytic results that allow for an accurate understanding of two-dimensional(2 D)cases are *** this work,we disclose an exactly solvable 2 D quasicrystal model with parity-time(PT)symmetry displaying exact *** the thermodynamic limit,we unveil that the extended-localized transition point,observed at the PT symmetry breaking point,is topologically characterized by a hidden winding number defined in the dual *** coupling waveguide platform can be used to realize the 2 D non-Hermitian quasicrystal model,and the excitation dynamics can be used to detect the localization features.

关键词： quasicrystals mobility edges non-Hermitian systems localization properties

Brucellosis of unknown origin with haemophagocytic syndrome:A case report

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World Journal of Clinical Cases 2021年第15期9卷 3649-3654页

作者： Li-Hong Tian zhi-Gao Dong xu-Yan Chen Lian-Jiang Huang ping-ping Xiao Department of Hematology and Rheumatology The Second Affiliated Hospital of Xiamen Medical CollegeXiamen 361021Fujian ProvinceChina Department of Laboratory The Second Affiliated Hospital of Xiamen Medical CollegeXiamen 361021Fujian ProvinceChina

BACKGROUND Brucellosis is a contagious bacterial disease caused by Brucella species,which is a leading zoonotic disease *** patients with brucellosis have a clear infection source;however,our case had a rare presentation of secondary haemophagocytic lymphohistiocytosis without any epidemiological *** SUMMARY A 50-year-old man was admitted to our hospital with a fever of unknown *** laboratory examinations,such as blood culture and bone marrow biopsy,the patient was diagnosed with brucellosis and secondary haemophagocytic *** antibiotic therapy,the patient was afebrile,and his haemogram recovered to normal,after which he was *** Brucellosis cannot be excluded in patients with clinically unexplained fever,even in those without epidemiologic history.

关键词： Brucella Brucellosis Haemophagocytic syndrome Haemophagocytic lymphohistiocytosis Fever Case report

Substrate effects on spin relaxation in two-dimensional Dirac materials with strong spin-orbit coupling

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npj Computational Materials 2023年第1期9卷 1880-1889页

作者： Junqing xu Yuan ping Department of Chemistry and Biochemistry University of CaliforniaSanta CruzCA 95064USA

Understanding substrate effects on spin dynamics and relaxation is of key importance for spin-based information ***, the key factors that determine such effects, in particular for materials with strong spin-orbit coupling (SOC), have notbeen well understood. Here we performed first-principles real-time density-matrix dynamics simulations with SOC and the electron-phonon and electron-impurity scattering for spin lifetimes (τ_(s)) of supported/free-standing germanene, a prototypical strong SOC 2DDirac material. We show that the effects of different substrates on τ_(s) can surprisingly differ by two orders of magnitude. We find thatsubstrate effects on τs are closely related to substrate-induced modifications of the SOC-field anisotropy, which changes the spin-flip scattering matrix elements. We propose a new electronic quantity, named spin-flip angle θ↑↓, to characterize spin relaxationthrough intervalley spin-flip scattering. We find that T_(s)^(-1) is approximately proportional to the averaged value of sin^(2)( θ↑↓/2 ) , whichserves as a guiding parameter of controlling spin relaxation.

关键词： material relaxation coupling

A review of the health effects and exposure-responsible relationship of diesel particulate matter for underground mines

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International Journal of Mining Science and Technology 2017年第5期27卷 831-838页

作者： Chang ping xu Guang Department of Mining Engineering and Metallurgical Engineering Western Australian School of MinesCurtin UniversityKalgoorlie 6430Australia

The increasing use of diesel-powered equipment in confined spaces(underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter(DPM). Miners in underground mines can be exposed to DPM concentrations far more than works in other industries. A great number of animal and epidemiological studies have shown that both short-term and long-term DPM exposure have adverse health effect. Based on reviews of related studies, especially some recent evidence, this paper investigated the long and short-term health effects based on animal studies and epidemiological studies. The exposure-response relationship studies were also explored and compared to the current DPM regulation or standards in some countries. This paper found that the DPM health effect studies specifically for miners are not sufficient to draw solid conclusions, and a recommendation limit of DPM concentration can be put in place for better protection of miners from DPM health risk. Current animal studies lack the use of species that have similar lung functions as human for understanding the cancer mode of action in human. And finally, the DPM health hazard will continue to be a challenging topic before the mode of action and reliable exposure-response relationship are established.

关键词： Diesel particulate matter (DPM) Underground mines Lung cancer Exposure-response relationship

Oscillation Theorems for Quasilinear Elliptic Differential Equations

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Acta Mathematica Sinica,English Series 2007年第7期23卷 1189-1198页

作者： zhi Ting xu School of Mathematical Sciences South China Normal University

By using vector Riccati transformation and averaging technique, some oscillation criteria for the quasilinear elliptic differential equation of second order,ΣNi,j=1Di[Ψ（y）Aij（x）｜Dy｜^p-2Djy]＋p（x）f（y）=0,are obtained. These theorems extend and include earlier results for the semilinear elliptic equation and PDE with p-Laplacian.

关键词： oscillation quasilinear elliptic equation second order vector Riccati transformation

Averaging Technique for the Oscillation of Second Order Damped Elliptic Equations

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Acta Mathematica Sinica,English Series 2008年第5期24卷 829-842页

作者： zhi Ting xu School of Mathematical Sciences South China Normal University Guangzhou 510631 P. R. China

By using the averaging technique, we establish some oscillation theorems for the second order damped elliptic differential equation N↑∑↓i,j=1 Di[AIY（x）Djy]＋N↑∑↓i=1 bi（x）Diy＋c（x）f（y）=0 which extend and... 详细信息

关键词： oscillation averaging technique second order elliptic differential equation damped