Directed translocation of a flexible polymer through a cone-shaped   channel
  Entropy-driven directed translocation of a flexible polymer through a cone-shaped channel is studied theoretically and using computer simulation. For a given length of the channel, the effective force of entropic origin acting on the polymer is calculated as a function of the apex angle of the channel. It is found that the translocation time is a non-monotonic function of the apex angle. By increasing the apex angle from zero, the translocation time shows a minimum and then a maximum. Also, it is found that regardless of the value of the apex angle, the translocation time is a uniformly decreasing function of the channel length. The results of the theory and the simulation are in good qualitative agreement. 
Narges Nikoofard, Hamidreza Khalilian, Hossein Fazli
cond-mat.soft