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X-ray flares of γ-ray bursts: Quakes of solid quark stars?

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Science china(physics,Mechanics & Astronomy) 2009年第2期52卷 315-320页

作者： XU RenXin1 & LIANG EnWei2.1 school of physics and state {2. laboratory of nuclear physics and technology, peking university, Beijing 100871, china 2.Department of physics, Guangxi university, Nanning 530004, china 1. school of physics and state {2. laboratory of nuclear physics and technology Peking University Beijing 100871 China 2. Department of physics Guangxi University Nanning 530004 China

A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103 to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

关键词： γ-rays bursts: X-rays neutron stars elementary particles

Magnetic moments of ^(33)Mg in the time-odd relativistic mean field approach

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Science china(physics,Mechanics & Astronomy) 2009年第10期52卷 1586-1592页

作者： LI Jian1,ZHANG Ying1,YAO JiangMing1 & MENG Jie1,2.1 school of physics,state {2. laboratory of nuclear physics and technology,peking university,Beijing 100871,china 2.0} and nuclear Energy Engineering,Beihang university,Beijing 100191,china school of physics State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China school of physics and {2. Energy Engineering Beihang University Beijing 100191 China

The configuration-fixed deformation constrained relativistic mean field approach with time-odd component has been applied to investigate the ground state properties of 33Mg with effective interaction *** ground state of 33Mg has been found to be prolate deformed,β2.0.2.,with the odd neutron in 1/2.330] orbital and the energy -2.1.85 MeV which is close to the data -2.2.06 *** magnetic moment -0.9134 μN is obtained with the effective electromagnetic current which well reproduces the data -0.7456 μN self-consistently without introducing any *** energy splittings of time reversal conjugate states,the neutron current,the energy contribution from the nuclear magnetic potential,and the effect of core polarization are discussed in detail.

关键词： magnetic moment binding energy time-odd component configuration-fixed deformation constrained calculation relativistic mean field theory

Shape phase transitions in nuclei:Effective order parameters and trajectories

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 88-97页

作者： ZHANG Yu1,2. HOU ZhanFeng2.& LIU YuXin2.3 1Department of physics, Liaoning Normal university, Dalian 11602.,{2. 2.epartment of physics and the state key laboratory of nuclear physics and technology, peking university, Beijing 100871,{2. 3Center of Theoretical nuclear physics, National laboratory of Heavy Ion Accelerator, Lanzhou 72.000,{2. 1. Department of physics Liaoning Normal University Dalian 116029 China2. Department of Physics and the State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China3. Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou 720000 China

We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2. ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02.) and B(E2. (L+2.1 → L1)/B(E2. 2. → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62.are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62.isotones is approximately monotonous due to the finiteness of nuclear system.

关键词： nuclear shape phase transition interacting boson model effective order parameter finite particle number effect transition trajectory

Kinetic characteristics of continuous flow polymerase chain reaction chip: A numerical investigation

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Science china(Technological Sciences) 2010年第7期53卷 1967-1972页

作者： WANG ShiYing1 & WANG Wei2.3 1 school of physics, peking university, Beijing {2., china 2.Institute of Microelectronics, peking university, Beijing {2., china 3 National key laboratory of Science and technology on Micro/Nano Fabrication, Beijing {2., china 1. school of physics Peking University Beijing 100871 China2. Institute of Microelectronics Peking University Beijing 100871 China3. National Key Laboratory of Science and Technology on Micro/Nano Fabrication Beijing 100871 China

Continuous flow PCR (polymerase chain reaction) chip holds impressive advantages compared to micro chamber PCR chip. In order to have better understanding of kinetic characteristics of continuous flow PCR chip, a comprehensive mathematical model is presented in this paper, including melting, annealing and extension phases of a typical PCR process which has the essence of a convection-diffusion-reaction system. Using this model, we can simulate the PCR process in series of reaction cycles. Numerical results show that the average sample velocity plays a significant role in affecting the amplification efficiency. Also, appropriate combination of the PCR mixture is important for high-quality DNA amplification. Giving a large initial DNA concentration range, the continuous flow PCR scheme holds excellent real-time detection ability theoretically. The present numerical model bridges the temperature distribution to the real DNA amplification, and thereby is able to successfully predict continuous flow PCR properties which are important for the chip design.

关键词： continuous flow PCR chip numerical simulation convection-diffusion-reaction system

Recent HERMES Results on DVCS from Proton and nuclear Targets

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原子核物理评论 2009年第S1期26卷 124-128页

作者： YE Hong-xue,MAO Ya-jun (school of physics and {2. key laboratory of nuclear physics and technology,peking university,Beijing 100871,china) school of physics and {2. key laboratory of nuclear physics and technology Peking UniversityBeijing 100871China

Spin structure is one of the fundamental subjects in the study of nucleon structure. Recently it is found that Generalized Parton Distributions(GPDs) are related to the total angular momentum carried by partons,which offers a possible solution to the spin puzzle in the first time. We get access to certain GPDs by looking at the azimuthal angle asymmetries attributed to the interference between Deeply Virtual Compton Scattering(DVCS) and Bethe-Heilter processes in HERMES experiment. By measuring the asymmetry with respect to transverse target polarization from proton target,a model-dependent constraint on Ju vs Jd is obtained. Another worldwide unique channel is nuclear DVCS. The preliminary results on asymmetries with respect to beam spin and beam charge are reported.

关键词： GPDs DVCS TTSA nuclear DVCS

β-decay studies of the neutron-rich ^(18,2.)N isotopes

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 53-60页

作者： HUA Hui, LI ZhiHuan, YE YanLin, JIANG DongXing, LOU JianLing, LI XiangQing & XU FuRong school of physics and state {2. laboratory of nuclear physics and technology, peking university, Beijing 100871, china 1. school of physics and state {2. laboratory of nuclear physics and technology Peking University Beijing 100871 China

The β-decay studies of neutron-rich 18,2.N isotopes have been performed using β-n, β-γ, and β-n-γ coincidence methods. The 18,2.N ions were produced by the fragmentation of the 2.Ne and 2.Mg beams, respectively, on a thick beryllium target. The time of flight of the emitted neutrons following the β-decay of 18,2.N was measured by a neutron detector system with wide energy detection range and low-energy detection threshold. In addition, several clover germanium detectors were used to detect the β-delayed γ-rays. The half-lives of the β-decays of 18N and 2.N were determined to be (619±2. ms and (82.9±7.5) ms, respec tively. Several new β-delayed neutron groups were observed with a total branching ratio of (6.98±1.46)% and (90.5±4.2.% for 18N and 2.N, respectively. The level schemes of 18O and 2.O were deduced. The experimental Gamow-Teller β-decay strengths of 18N and 2.N to these levels were compared with the shell model calculations.

关键词： β-delayed neutron decay 18 2.N neutron detector system branching ratio Gamow-Teller strength

Near-field properties of a shell nanocylinder pair with gain materials

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Chinese physics B 2012年第11期21卷 388-392页

作者：王乔吴世法王晓钢 MOE key laboratory of Materials Modification by Beams School of Physics&Optoelectronic EngineeringDalian University of Technology state key {2. of nuclear physics and technology School of PhysicsPeking University

We study the near-field response of a shell nanocylinder pair, with its core filled by gain materials, using a two- dimensional finite-difference time-domain method. It is shown that the gain materials in the core of the cylinder can compensate for the intrinsic absorption of the metal shell, leading to local-field enhancement in the gap of the active pair. A linear dependence is found between the field enhancement and the gain coefficient at resonance. The detailed physics is studied by calculating the electrical-field distribution of the shell pair filled with different gain materials. The influence of the gap width and the shell thickness on the interaction of two adjacent active shell cylinders is also investigated.

关键词： shell nanocylinder pair gain material local-field enhancement

Properties of the 3/2.-[52.] band in the odd-N rare-earth nuclei

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 37-43页

作者： CHEN Liang1,2. ZHOU XiaoHong1,2. ZHANG YuHu1, ZHANG ShuangQuan3 & ZHU LiHua4 1Institute of Modern physics, Chinese Academy of Sciences, Lanzhou 730000, china 2.raduate {2. of Chinese Academy of Sciences, Beijing 100049, china 3state key laboratory of nuclear physics and technology, school of physics, peking university, Beijing 100871, china 4china Institute of Atomic Energy, Beijing 102.13, china 1. Institute of Modern physics Chinese Academy of Sciences Lanzhou 730000 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing 100871 China4. China Institute of Atomic Energy Beijing 102413 China

High-spin states in 161Er have been studied experimentally via the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. Three rotational bands built on the 5/2.[642., 3/2.[52.], and 11/2.[505] configurations have been extended up to high-spin states, and particularly, the α = -1/2.branch of the ground state 3/2.[52.] band has been revised significantly. It is found that signature inversion occurs in the 3/2.[52.] band after the band crossing in 161Er. The systematics of the signature inversion associated with the 3/2.[52.] configuration in the rare-earth region is discussed. The band properties are analyzed within the framework of a triaxial particle-rotor model, and a triaxial deformation is proposed to the 3/2.[52.] band.

关键词： high-spin states signature inversion triaxial particle-rotor model

Modeling the intracellular dynamics for Vif-APO mediated HIV-1 virus infection

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Chinese Science Bulletin 2010年第22期55卷 2329-2340页

作者： WANG Yi1,2.& LAI LuHua1,3 1 Center for Theoretical Biology, peking university, Beijing 100871,{2. 2.3}, peking university, Beijing 100871,{2. 3 BNLMS, state key laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, peking university, Beijing 100871,{2. Center for Theoretical Biology Peking University Beijing 100871 China school of physics Peking University Beijing 100871 China BNLMS State Key Laboratory for Structural Chemistry of Unstable and Stable Species College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

The viral infectivity factor (Vif) was found to be essential for controlling HIV-1 virus infectivity. It targets cellular antiviral proteins in APOBEC family (APO) to trigger its fast degradation and inhibits APO packaging into nascent virion. In the present study, we propose a mathematical model to quantitatively study the intracellular dynamics of these typical virus-host interactions. Four sets of published experimental data were compared with simulation results to justify the model. Systematic parameter sensitivity and perturbation analysis showed that parameters related to APO are crucial to the infectivity of newly synthesized HIV-1 virus. Interestingly, we discovered that the synthesis rate of the viral structure protein Gag and the required number per nascent virion are optimized to achieve high virion production with minimal level of packaged APO, and large portion of model parameters are beneficial to virus only within a relatively small range. Furthermore, minor variations in several parameters related to viral protein Tat, the activator of viral RNA synthesis, were found to induce switch-like behaviors on both incorporated Vif and APO. These findings may provide new insights for understanding the high mutation rate of HIV-1 virus and its latency, as well as help identify key targets for therapeutic design.

关键词：病毒感染载脂蛋白 HIV 细胞内动力学抗病毒蛋白建模介导