摩擦不对称耦合布朗马达的定向输运

Investigation on the directional transportation of coupled Brownian motors with asymmetric friction

本文研究了耦合布朗马达在溶液摩擦对称性破缺条件下的定向输运问题.详细讨论了溶液阻尼系数比,周期外力以及耦合作用对布朗粒子定向输运的影响.研究发现:溶液摩擦的不对称性不仅能促进摩擦棘轮的定向输运,且合适的溶液阻尼系数比还可以使耦合棘轮的定向输运达到最强.此外,一定摩擦阻尼条件下外力振幅可以使耦合粒子的定向输运呈现多峰结构.研究还发现合适的自由长度和耦合强度也能增强摩擦棘轮的输运特性.研究结果不仅能够启发实验上选取合适的摩擦阻尼来优化布朗马达的输运,也可为信息容量大、反应速度快的纳米器件的制备提供一定的理论参考.

Biological molecular motors exist in cells widely.They can make use of intracellular free energy to complete all kinds of internal biological transports by transforming chemical energy into mechanical energy.The kind of directional movement of biological molecular motors plays a very important role in intracellular material transportation.In order to study the transport mechanism of molecular motors further,a large number of ratchet models are proposed,such as rocking ratchets and flashing ratchets.By investigating various kinds of ratchets we can not only understand the directional movement mechanism of Brownian particles,but can find suitable conditions in which the performance of Brownian motors’ directional transportation could be enhanced.Meanwhile,the investigation of ratchets could also be applied in manufacturing nanometer devices.At present,the directional transportation of Brownian ratchet has attracted extensive interests of researchers.In general,most friction factors of Brownian ratchet models are considered unit.In fact,the concentration of solutions and cell fluid impurity affect the actual frictional damping conditions,so the real frictional coefficient of Brownian motors is often changed.In addition,lots of experimental studies have shown that the movement of Brownian motors is collectively directed motion and the kind of directional movement is induced by intermolecular coupling interaction.As a result,it is more valuable to investigate the transporting performance of coupled Brownian particles that existed in different frictional damping conditions.In order to enhance the transporting performance of Brownian ratchet in different frictional damping conditions,we discuss how the frictional damping factor influences the directional movement of coupled Brownian particles deeply when Brownian particles drag loads.In this paper,we established the overdamped frictional ratchets,and then we investigated how frictional damping coefficient ratio,coupling strength and external force amplitude affect the transportation of coupled Brownian ratchets.On the basis of the investigation,some interesting results are found.The directional transport of frictional ratchets can be promoted by adjusting the frictional damping factor.Besides,the transportation can obtain the maximum under the appropriate friction factor case.In addition,under certain frictional damping condition,the directional transportation of the friction ratchets present multi-peak structure as the external force amplitude increases.Meanwhile,the appropriate free length and coupling strength can also enhance the transportation characteristic of frictional ratchets.All conclusions obtained in this paper can not be applied in selecting suitable frictional damping conditions experimentally to improve the directional transportation of coupled Brownian ratchets,but they can also be used in developing and manufacturing nanometer devices.