Investigation On The Energy Conversion Efficiency Of The Feedback-coupled Ratchet

At present,the directed transport of biomolecular motors has attracted extensive interests of researchers.Molecular motors are a large class of enzymatic protein biomolecules widely existing in organisms.There are many kinds of molecular motors and they are mainly involved in the transport of organelles within cells,cell division.The size of molecular motors is usually on the nanometer scale,which is very similar to the motion characteristics of Brownian particles in physics.Physical models which are correspond to reality are constructed to study the directed transport character of molecular motors.Most of the molecular motors in the cell have very high efficiency of external work.Nevertheless,the efficiency of the artificial motor is still far from that of the experimental results.Therefore,it is still a very important research topic to theoretically improve the efficiency of external work of coupled motors.With the development of feedback technique,it is necessary to further study the energy conversion efficiency of feedback ratchet theoretically.Through the study of different feedback ratchets,we can not only deeply understand the directed transport mechanism of particles,but also help to get insight into the transport process in biomedical.At the same time,it can also provide some theoretical guidance on how to improve the accurate delivery of drug and the effective utilization rate of medicine.By means of numerical simulation of langevin equation,we discuss the direced transport of the feedback controling ratchet without load,the directed transport and the energy conversion efficiency of coupled Brownian ratchet when they drag loads are discussed.The effects of free length,coupling strength,external force amplitude and pulsing phase on the direced transport of coupling particles are analyzed systematically.It is found that both the appropriate free length and the coupling strength can enhance the directed transport of the feedback controling ratchet without load.Meanwhile,there is an optimal value of external force amplitude to maximize the reverse probability flow of the coupled particles,and the directed transport of the feedback ratchet can be improved if the thermal noise intensity is appropriate.In addition,appropriate time scale can also promote the directed transport of feedback coupled ratchet.It can also be observed that the directed transport of the feedback pulsing ratchets would be futher facilitated by adjusting suitable free length and coupling strength.Meanwhile,the energy conversion efficiency of coupled particles can obtain the maximum under some certain free length and coupling strength.Futhermore,in an evolutive cycle,the appropriate pulse phase can lead to current reversal,and the directed transport of the ratchet can be enhanced by modulating the phase.The conclusion can not only be used to design appropriate feedback controling to optimize the directed transport character of ratchet,but also provide some theoretical references for the accurate delivery of biological medicine and research of the improvement of nano-devices performance.