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Polymer Translocation

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Chinese Journal of Polymer Science 2023年第5期41卷 683-698,I0007页

作者： lu-Wei lu Zhen-Hua Wang An-Chang Shi yu-yuan lu Li-Jia An State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China Hefei 230026China Department of Physics and Astronomy McMaster UniversityHamiltonOntario L8S4M1Canada

The translocation of a polymer through a pore that is much smaller than its size is a fundamental and actively researched topic in polymer *** understanding of the principles governing polymer translocation provides important guidance for various practical applications,such as the separation and purification of polymers,nanopore-based single-molecule deoxyribonucleic acid/ribonucleic acid(DNA/RNA)sequencing,transmembrane transport of DNA or RNA,and infection of bacterial cells by *** past several decades have seen great progresses on the study of polymer *** we present an overview of theoretical,experimental,and simulational stduies on polymer translocation,focusing on the roles played by several important factors,including initial polymer conformations,external fields,polymer topology and architectures,and confinement *** highlight the physical mechanisms of different types of polymer translocations,and the main controversies about the basic rules of translocation *** compare and contrast the behaviors of force-induced versus flow-induced translocations and the effects of unknotted versus knotted ***,we mention several opportunities and challenges in the study of polymer translocation.

关键词： Polymer translocation Knotted polymers Translocation time Critical flux

Size and Dynamics of Ring Polymers under Different Topological Constraints

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Chinese Journal of Polymer Science 2023年第4期41卷 516-524,I0006页

作者： Jiang-Yang Mo Zhen-Hua Wang yu-yuan lu Li-Jia An State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China University of Science and Technology of China Hefei230026China

The impact of ring polymer length N and the influence of interchain and intrachain interactions on the size and dynamic behaviors of ring polymers,including the structural relaxation time τ_(R) and self-diffusion coefficient D,remain poorly understood at present due to a lack of systematic studies with relatively large N *** work addressed this issue by applying dynamic Monte Carlo simulations with independently tuned interchain and intrachain interactions to investigate the size and dynamics of the ring melts with chain lengths over a wide range of 0.2N_(e)≤N≤80N_(e)(N_(e) is the entanglement length of corresponding linear chains)under different topological constraints,including all-crossing and intercrossing *** found that it was inappropriate to treat the unknotting constraint free energy of the ring chains in the melts as the free energy contributed by the excluded volume interactions of polymers in a good *** exponents of 2.5 and 1.5 reflecting the Ndependence of τ_(R) were obtained for long ring chains in non-crossing and intra-crossing systems,respectively,suggesting that the ring chains behaved as individual clusters and exhibited Zimm-like dynamics in intra-crossing systems.A single scaling exponent of-2 reflecting the Ndependence of D was obtained for ring chains in non-crossing and intra-crossing systems,indicating that the intrachain constraints affected only the value of D,and had little influence on the scaling relationship between D and ***,the extended Stokes-Einstein relation broke down for the ring chains in the non-crossing and intra-crossing systems because the structural relaxation and translational diffusion were decoupled for the short ring systems,while both the translational diffusion and rotational relaxations,as well as diffusion at short and long time scales,were decoupled for long ring systems.

关键词： Ring polymer Topological constraint Extended Stokes-Einstein relation Monte Carlo simulation

Effect of Interfacial Adsorption on the Stability of Thin Polymer Films in a Solvent-induced Process

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Chinese Journal of Polymer Science 2021年第4期39卷 501-511,I0008页

作者： Lin Xu Tong-Fei Shi Li-Jia An yu-yuan lu Li-Na Wang Innovation Center for Textile Science and Technology Donghua UniversityShanghai201620China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Testing and Analysis Center Hebei Normal UniversityShijiazhuang 050024China

The stability of ultrathin polymer films plays a crucial role in their technological ***,we systematically investigated the influence of interfacial adsorption in physical aging and the stability of thin polymer films in the solvent-induced *** further identify the stability mechanism from the theory of thin film *** results show that the aging temperature and film thickness can strongly influence the stability of thin PS films in acetone *** aging can greatly improve the stability of thin polymer films when the aging temperature T_(aging1)>T_(g).A thinner PS film more quickly reaches a stable state via physical *** short aging time,the formation of the adsorbed layer can reduce the polar interaction;however,it slightly influences the stability of thin polymer films in the solvent-induced *** later aging stage,the conformational rearrangement of the polymer chains induced by the interfacial effect at the aging temperature Taging1 plays an important role in stabilizing the thin polymer ***,at T_(aging2)luences the stability of the thin polymer *** formation of the adsorbed layer at Taging2 can reduce the short-range polar interaction of the thin film system and cannot suppress the instability of thin polymer films in the solvent-induced *** results provide further insight into the stable mechanism of thin polymer films in the solvent-induced process.

关键词： Thin polymer film Interfacial adsorption Dewetting Swelling process

Diffusion of a Ring Threaded on a Linear Chain

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Chinese Journal of Polymer Science 2020年第12期38卷 1409-1417页

作者： Zhen-Hua Wang yu-yuan lu Hui Jin Chuan-Fu luo Li-Jia An State KeyLaboratory of Polymer Physics and Chemistry Changchun Istitute ofpplied Chemistry Chinese Academy of SciencesChangchun 130022 China University ofScience and Technology of China Hefei 230026China Changchun Istitute of Optics Fine Mechanics and PhysisChinese Acadermy of SciencesChangchun 130033China

A mesoscopic simulation is applied to investigate the effects of hydrodynamic interactions and axial chains on the dynamics of threaded *** hydrodynamic interactions significantly speed up the diffusion and relaxation of both free and threaded *** decoupled diffusion and relaxation dynamics indicate the broken of the Einstein-Stokes *** diffusion of a ring threaded on a flexible chain exhibits a synergism effect compared to that on an axial rod,which originates from the self-diffusion of the ring and the reptation-like motion of the axial ***,hydrodynamic interactions significantly improve the synergism effect,leading to an enhanced sliding motion of the threaded *** faster sliding of threaded rings suggests that the entropic barrier is negligible,which agrees well with the basic assumption of barrier-less confining tube at equilibrium in tube *** results provide a new perspective on analysis of the effects of topology constraints on polymer dynamics.

关键词： Hydrodynamic interactions Threaded ring Sliding dynamics Diffusion and relaxation

Exploring Nonlinear Rheological Behaviors in Entangled Semi-flexible Polymer Melts

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Chinese Journal of Polymer Science 2024年第11期42卷 1811-1823,I0014页

作者： Li-Cheng Ma Yong-Jin Ruan Zhen-Hua Wang yu-yuan lu Li-Jia An State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026China

This study utilizes molecular dynamics simulation to investigate the complex dynamics of entangled semi-flexible polymer *** investigation reveals a significant stress overshoot phenomenon in the systems,demonstrating the intricate interplay between shear rates,chain orientation,and chain stretching ***,the identification of metastable states,characterized by a dual-plateau phenomenon in the shear stress-strain curve at specific Rouse-Weissenberg number Wi_(R),showcases the system’s responsiveness to external perturbations and its transition to stable shear banding ***,the analysis of flow field deviations uncovers a progression of shear bands with increasing Wi_(R),displaying distinct behaviors in the system’s dynamics under different shear rates and chain *** findings challenge established theoretical frameworks and advocate for refined modelling approaches in polymer rheology research.

关键词： Semi-flexible polymer melts Molecular dynamics simulation Stress overshoot Shear banding Entanglement

Evolution of Polymer Melt Conformation and Entanglement under High-Rate Elongational Flow

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Chinese Journal of Polymer Science 2024年第12期42卷 2021-2029,I0012页

作者： Jia-Peng Zhang Li-Cheng Ma Yong-Jin Ruan yu-yuan lu Li-Jia An State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026China

Using molecular dynamics(MD)simulations,this study explores the fluid properties of three polymer melts with the same number of entanglements,Z,achieved by adjusting the entanglement length Ne,while investigating the evolution of polymer melt conformation and entanglement under high-rate elongational *** identification of a master curve indicates consistent normalized linear viscoelastic *** findings regarding the steady-state viscosity at various elongational rates(Wi_(R)>4.7)for polymer melts with the same Z have been uncovered,challenging existing tube ***,the study demonstrates the potential for normalizing the steady-state elongational viscosity at high rates(Wi_(R)>4.7)by scaling with the square of the chain contour ***,the observed independence of viscosity on the elongational rate at high rates suggests that higher rates lead to a more significant alignment of polymer chains,a decrease in entanglement,and a stretching in contour length of polymer ***-level tracking of tagged chains further supports the assumption of no entanglement under rapid elongation,emphasizing the need for further research on disentanglement in polymer melts subjected to high-rate elongational *** results carry significant implications for understanding and predicting the behavior of polymer melts under high-rate elongational flow conditions.

关键词： Polymer rheology High-rate elongational flow Entangled polymer melts Molecular dynamics simulations Disentanglement

IMPROVED METHOD FOR RNA SECONDARY STRUCTURE PREDICTION'

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Chinese Chemical Letters 1993年第8期4卷 737-740页

作者： Xue Mei yuan yu luO lu Hua LAI Xiao Jie XU Institute of Physical Chemistry,Peking University,Beijing 100871

A simple stepwise folding process has been developed to simulate RNA secondary structure *** for the energy parameters of various loops were included in the *** possible types of pseudoknots including the well known H-type pseudoknot were permitted to occur if *** have applied this approach to e number of RNA *** prediction accuracies we obtained were higher than those in published papers.

关键词： RNA IMPROVED METHOD FOR RNA SECONDARY STRUCTURE PREDICTION 吐司

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高分子黏弹性的经典唯象模型

高分子学报 2016年第6期26卷 688-697页

作者：卢宇源安立佳王健中国科学院长春应用化学研究所高分子物理与化学国家重点实验室长春130022

高分子流体的黏弹性质是高分子科学和工程中一个非常重要的研究领域.与简单黏性液体和弹性固体不同,外场作用下缠结高分子流体呈现出复杂的黏弹性行为,例如应力不仅仅与应变幅度或应变速率有关,还与整个形变历史相关.近半个世纪以来,人... 详细信息

高分子流体的黏弹性质是高分子科学和工程中一个非常重要的研究领域.与简单黏性液体和弹性固体不同,外场作用下缠结高分子流体呈现出复杂的黏弹性行为,例如应力不仅仅与应变幅度或应变速率有关,还与整个形变历史相关.近半个世纪以来,人们建立了很多描述这些复杂黏弹性质的模型和理论,其中一类是基于连续性介质力学原理的唯象模型,例如:Maxwell模型、Voigt-Kelvin模型和在时空上所有参数为常量的连续性模型;另一类是瞬态网络模型,该模型把缠结点考虑成瞬态交联点,高分子链看成珠簧链;还有一类是微观分子理论,其中最著名的是"管子模型".本文首先介绍缠结高分子流体的线性黏弹性响应和Boltzmann叠加原理的基本概念,然后,重点综述描述高分子黏弹性质仍非常有实际应用价值的3个经典唯象模型,包括Maxwell模型、Voigt-Kelvin模型和瞬态网络模型,特别是这些理论的详细推导和存在的主要问题.关于高分子黏弹性的微观理论将在其它综述中单独介绍.

关键词：黏弹性 Maxwell模型 Voigt-Kelvin模型瞬态网络模型 Boltzmann叠加原理

Co/Co_(7)Fe_(3)heterostructures with controllable alloying degree on carbon spheres as bifunctional electrocatalyst forrechargeable zinc-air batteries

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 476-487页

作者： Junkang Chen Yongyue Zhuang Yanxin Qiao yu Zhang Aihua yuan Hu Zhou School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China School of Environmental and Chemical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

Exploring efficient and nonprecious metal electrocatalysts of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is crucial for developing rechargeable zinc-air batteries(ZABs).Herein,an alloying-degree control strategy was employed to fabricate nitrogen-doped carbon sphere(NCS)decorated with dual-phase Co/Co_(7)Fe_(3)heterojunctions(CoFe@NCS).The phase composition of materials has been adjusted by controlling the alloying *** optimal CoFe_(0.08)@NCS electrocatalyst displays a half-wave potential of 0.80 V for ORR and an overpotential of 283 mV at 10 mA·cm^(-2)for OER in an alkaline *** intriguing bifunctional electrocatalytic activity and durability is attributed to the hierarchically porous structure and interfacial electron coupling of highly-active Co_(7)Fe_(3)alloy and metallic Co *** the CoFe_(0.08)@NCS material is used as air-cathode catalyst of rechargeable liquid-state zinc-air battery(ZAB),the device shows a high peak power-density(157 mW·cm^(-2))and maintains a stable voltage gap over 150 h,outperforming those of the benchmark(Pt/C+RuO_(2))-based *** particular,the as-fabricated solid-state flexible ZAB delivers a reliable compatibility under different bending *** work provides a promising strategy to develop metal/alloy-based electrocatalysts for the application in renewable energy conversion technologies.

关键词： bifunctional electrocatalysts oxygen reduction reaction oxygen evolution reaction zinc-air battery metal/alloy carbon sphere