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Combined effects of headgroup charge and tail unsaturation of lipids on lateral organization and diffusion of lipids in model biomembranes

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Chinese physics B 2017年第4期26卷 494-501页

作者：陈晓洁梁清 center for statistical and theoretical condensed matter physics and Department of physics Zhejiang Normal UniversityJinhua 321004China

Lateral organization and dynamics of lipids in plasma membranes are crucial for several cellular processes such as signal transduction across the membrane and still remain *** this paper,using coarse-grained molecular dynamics simulation,we theoretically study the combined effects of headgroup charge and tail unsaturation of lipids on the lateral organization and diffusion of lipids in ternary lipid *** neutral ternary lipid bilayers composed of saturated lipids,unsaturated lipids,and cholesterols,under the conditions of given temperature and components,the main factor for the phase separation is the unsaturation of unsaturated lipids and the bilayers can be separated into liquid-ordered domains enriched in saturated lipids and cholesterols and liquid-disordered domains enriched in unsaturated *** the headgroup charge is introduced,the electrostatic repulsion between the negatively charged lipid headgroups will increase the distance between the charged *** find that the lateral organization and diffusion of the lipids in the（partially） charged ternary lipid bilayers are determined by the competition between the headgroup charge and the unsaturation of the unsaturated *** the bilayers containing unsaturated lipids with lower unsaturation,the headgroup charge plays a crucial role in the lateral organization and diffusion of *** headgroup charge may make the lipid domains unstable and even can suppress phase separation of the lipids in some ***,in the bilayers containing highly unsaturated lipids,the lateral organization and diffusion of lipids are mainly dominated by the unsaturation of the unsaturated *** work may provide some theoretical insights into understanding the formation of nanosized domains and lateral diffusion of lipids in plasma membranes.

关键词： biomembrane phase separation molecular dynamics simulation coarse grain

Quark Number Susceptibility around the Chiral Critical End Point

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Chinese physics Letters 2015年第2期32卷 39-42页

作者：蒋宇侯丰尧罗翠柏宗红石 center for statistical and theoretical condensed matter physics Zhejiang Normal University State Key Laboratory of theoretical physics Institute of Theoretical PhysicsChinese Academy of Sciences Department of physics Nanjing University Joint center for Particle

We calculate the quark number susceptibility （QNS） around the chiral critical end point （CEP）. The CEP is found to be located at （μc,Tc）= （80 MeV, 148 MeV） where μc and Tc are the critical chemical potential and temperature, respectively. The QNS is found to have the highest and sharpest peak at the CEP. It is also found that, when the chemical potential μ is in the range of 60MeV≤ μ ≤ 110MeV, the QNS near the transition temperature is larger than the free field result, which indicates that the space-like damping mode dominates the degree of freedom of motion near the CEP.

关键词： CEP QCD Quark Number Susceptibility around the Chiral Critical End Point

Phase Diagram of XY Model with Nematic Coupling on the Simple Cubic Lattice

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Communications in theoretical physics 2012年第1期57卷 166-168页

作者：吕建平陈庆虎 Department of physics China University of Mining and Technology Department of physics Zhejiang University center for statistical and theoretical condensed matter physics Zhejiang Normal University

Using cluster Monte Carlo method, we numerically investigate the coupling on the simple cubic lattice. We determine critical lines belong to the criticality in the XY model with nematic three-dimensional XY universality class in variable of θ （2θ） between the XY-ferromagnetic （nematic） and disordered states. Fhrthermore, the phase transition between the XY-ferromagnetic and the nematie states is found to be in the three-dimensional Ising universality class. The critical points are determined from the intersections of Binder ratios for various system sizes. With two sets of critical points obtained, we finally construct the phase diagram on the A-J plane.

关键词： nematic phase phase diagram scaling analysis

Wigner Solution to the Quark Gap Equation in the Nonzero Current Quark Mass

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Chinese physics Letters 2012年第4期29卷 31-34页

作者： JIANG Yu GONG Hao SUN Wei-Min ZONG Hong-Shi center for statistical and theoretical condensed matter physics Zhejiang Normal UniversityJinhua 321004 Department of physics Nanjing UniversityNanjing 210093 Joint center for Particle Nuclear Physics and CosmologyNanjing 210093

From the graphical representation of the Dyson-Schwinger equation for the dressed gluon propagator it is shown that the gluon propagator in the Wigner phase should be different from that in the Nambu *** on this analysis,we propose a modified gluon propagator to reflect this *** such a modified gluon propagator,in the framework of the Nambu Jona Lasinio (NJL) model,we obtain the Wigner solution to the quark gap equation at finite current quark mass,which has not been found in *** provides a new point of view to study partial restoration of chiral symmetry at finite temperature and chemical potential.

关键词： potential phase quark

Coarse-grained simulations on interactions between spectrins and phase-separated lipid bilayers

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Chinese physics B 2021年第6期30卷 703-710页

作者： Xuegui Lin Xiaojie Chen Qing Liang center for statistical and theoretical condensed matter physics and Department of physics Zhejiang Normal UniversityJinhua 321004China Department of Industrial Automation Guangdong Polytechnic CollegeZhaoqing 526100China

Spectrin, the principal protein of the cytoskeleton of erythrocyte, plays a crucial role in the stability and flexibility of the plasma membrane of erythrocyte. In this work, we investigate the interactions between spectrins and phase-separated lipid bilayers using coarse-grained molecular dynamics simulation. We focus on the preference of spectrins with different lipids, the effects of the anionic lipids and the residue mutation on the interactions between spectrins and the lipid bilayers. The results indicate that spectrins prefer to contact with phosphatidylethanolamine(PE) lipids rather than with phosphatidylcholine(PC) lipids, and tend to contact with the liquid-disordered(Ld) domains enriched in unsaturated ***, the anionic lipids, which show specific interaction with the positively charged or polar amino acids on the surface of the spectrins, can enhance the attraction between the spectrins and lipid domains. The mutation leads to the decrease of the structural stability of spectrins and increases the curvature of the lipid bilayer. This work provides some theoretical insights into understanding the erythrocyte structure and the mechanism of some blood diseases.

关键词： protein lipid bilayer interaction molecular dynamics simulation

A Model-Independent Discussion of Quark Number Density and Quark Condensate at Zero Temperature and Finite Quark Chemical Potential

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Chinese physics Letters 2015年第12期32卷 14-17页

作者：徐书生蒋宇史潮崔钫宗红石 Department of physics Nanjing University Nanjing 210093 center for statistical and theoretical condensed matter physics Zhejiang Normal University Jinhua 321004 Joint center for Particle Nuclear Physics and Cosmology Nanjing 210093 State Key Laboratory of theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190

Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics （QCD）. By means of the generating functional method, we prove that the quark propagator actually depends on p4 ＋ iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain # when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain # the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value.

关键词： QCD A Model-Independent Discussion of Quark Number Density and Quark Condensate at Zero Temperature and Finite Quark Chemical Potential

Unified analytical treatments of qubit-oscillator systems

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Chinese physics B 2013年第6期22卷 369-379页

作者：贺树张瑜瑜陈庆虎任学藻刘涛汪克林 School of Science Southwest University of Science and Technology center for Modern physics Chongqing University Department of physics Zhejiang University center for statistical and theoretical condensed matter physics Zhejiang Normal University Department of Modern physics University of Science and Technology of China

An effective scheme within two displaced bosonic operators with equal positive and negative displacements is extended to study qubit-oscillator systems analytically in a unified way. Many previous analytical treatments, such as generalized rotating-wave approximation （GRWA） [Phys. Rev. Lett. 99, 173601 （2007）] and an expansion in the qubit tunneling matrix element in the deep strong coupling regime [Phys. Rev. Lett. 105, 263603 （2010）] can be recovered straightforwardly within the present scheme. Moreover, further improving GRWA and the extension to the finite-bias case are implemented easily. The algebraic formulae for the eigensolutions are then derived explicitly and uniquely, which work well in a wide range of the coupling strengths, detunings, and static bias including the recent experimentally accessible parameters. The dynamics of the qubit for an oscillator in the ground state is also studied. At the experimentally accessible coupling regime, GRWA can always work well. When the coupling is enhanced to the intermediate regime, only the improving GRWA can give the correct description, while the result of GRWA shows strong deviations. The previous Van Vleck perturbation theory is not valid to describe the dynamics in the present-day experimentally accessible regime, except for the strongly biased cases.

关键词： numerical exact solution qubit-oscillator system dynamics

Cholesterol-induced deformation of the gramicidin A channel inhibiting potassium ion binding and transport

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Chinese physics B 2024年第5期33卷 696-702页

作者：肖盼曹宇朱瑾梁清 center for statistical and theoretical condensed matter physics & Department of physics Zhejiang Normal UniversityJinhua 321004China Zhejiang Institute of Photoelectronics & Zhejiang Institute for Advanced Light Source Zhejiang Normal UniversityJinhua 321004China

Gramicidin A(gA)is a kind of antibiotic peptide produced by bacillus brevis and it can dimerize across lipid bilayers to form a monovalent cation *** this work,we investigate the impact of cholesterol in the lipid bilayer on the binding of potassium ions with the gA channel and the transport of the ions across the *** results indicate that cholesterol can significantly influence the conformational stability of the gA channel and cause the channel deformation which inhibits the potassium ion binding with the channel and transport across the *** work provides some molecular insights into understanding of influence of lipids on the activity of gA channel in both model membranes and plasma membranes of intact cells.

关键词： gramicidin A lipid bilayer molecular dynamics interaction

Macroscopic Quantum Coherence in Magnetic Molecular Clusters

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Chinese physics Letters 2001年第5期18卷 687-689页

作者： JIN Yan-Hong NIE Yi-Hang LIANG Jiu-Qing PU Fu-Cho Institute of physics and center for condensed matter physics Chinese Academy of SciencesBeijing 100080 Institute of theoretical physics and Department of physics Shanxi UniversityTaiyuan 030006

The oscillation of tunnel splitting in Fe8 molecular clusters is obtained as a function of magnetic field applied along the hard axis by means of instanton method with both semiclassical treatment and the effective potential field description of quantum spin *** theoretical splittings of the instanton method are compared with the numerical result by diagonalization of spin Hamilton operator and experimental *** taking the appropriate parameters,our theory formula yields the result as the same as the experimental observation.

关键词： splitting instant oscillation