Tensile elasticity of a freely jointed chain with reversible hinges,Soft Matter

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Tensile elasticity of a freely jointed chain with reversible hinges
Soft Matter ( IF 2.9 ) Pub Date : 2021-2-1 , DOI: 10.1039/d1sm00053e
Geunho Noh ₁ , Panayotis Benetatos

Affiliation

Many biopolymers exhibit reversible conformational transitions within the chain, which affect their bending stiffness and their response to a stretching force. For example, double stranded DNA may have denatured “bubbles” of unzipped single strands which open and close randomly. In other polymers, the transitions may be due to the reversible attachment and detachment of ligands on ligand–receptor complexes along the backbone. Semiflexible bundles under tension formed by the reversible attachment of cross-linkers, on a coarse-grained level, exhibit similar behaviour. The simplest theoretical model which captures what the above mentioned systems have in common is a freely jointed chain (FJC) with reversible hinges. Each hinge can be open, as in the usual FJC, or closed forcing the adjacent segments to align (stretch). In this article, we analyse it in the Gibbs ensemble. Remarkably, even though the usual FJC in the thermodynamic limit exhibits ensemble equivalence, the reversible FJC exhibits ensemble inequivalence. Even though a mean field treatment suggests a continuous phase transition to a fully hinged state at a certain force, the generating function method (“necklace model”) shows that there is no phase transition. However, there is a crossover between the two states with clearly different responses. In the low force (linear response) regime, the reversible FJC has higher tensile compliance than its usual counterpart. In contrast, in the strong force regime, the tensile compliance of the reversible FJC is much lower than that of the usual FJC.

中文翻译：

带有可逆铰链的自由连接链的拉伸弹性

许多生物聚合物在链中表现出可逆的构象转变，这影响了它们的弯曲刚度和对拉伸力的响应。例如，双链DNA可能具有变性的未压缩单链随机打开和闭合的“气泡”。在其他聚合物中，这些转变可能是由于配体沿骨架的可逆附着和脱离。在交联剂的可逆连接处形成的粗颗粒水平下，在张力作用下的半柔性束表现出相似的行为。捕获上述系统的共同点的最简单理论模型是带有可逆铰链的自由连接链（FJC）。每个铰链可以像通常的FJC中那样打开，也可以关闭以迫使相邻的段对齐（拉伸）。在本文中，我们在吉布斯合奏中对其进行分析。值得注意的是，即使在热力学极限中通常的FJC表现出整体的等价性，可逆FJC表现出整体的不等价性。即使平均场处理表明以一定的力从连续的相变到完全铰接状态，生成函数方法（“项链模型”）显示没有相变。但是，这两个州之间的交叉反应明显不同。在低力（线性响应）状态下，可逆FJC的拉伸柔度比通常的FJC高。相反，在强力状态下，可逆FJC的拉伸柔度远低于通常的FJC。可逆FJC表现出整体不等式。即使平均场处理表明以一定的力从连续的相变到完全铰接状态，生成函数方法（“项链模型”）显示没有相变。但是，这两个州之间的交叉反应明显不同。在低力（线性响应）状态下，可逆FJC的拉伸柔度比通常的FJC高。相反，在强力状态下，可逆FJC的拉伸柔度远低于通常的FJC。可逆FJC表现出整体不等式。即使平均场处理表明以一定的力从连续的相变到完全铰接状态，生成函数方法（“项链模型”）显示没有相变。但是，这两个州之间的交叉反应明显不同。在低力（线性响应）状态下，可逆FJC的拉伸柔度比通常的FJC高。相反，在强力状态下，可逆FJC的拉伸柔度远低于通常的FJC。两国之间的交往有着明显不同的反应。在低力（线性响应）状态下，可逆FJC的拉伸柔度比通常的FJC高。相反，在强力状态下，可逆FJC的拉伸柔度远低于通常的FJC。两国之间的交往有着明显不同的反应。在低力（线性响应）状态下，可逆FJC的拉伸柔度比通常的FJC高。相反，在强力状态下，可逆FJC的拉伸柔度远低于通常的FJC。

更新日期：2021-02-25

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