  Transport through nano-channels plays an important role in many biological
processes and industrial applications. Gaining insights into the functioning of
biological transport processes and the design of man-made nano-devices requires
an understanding of the basic physics of such transport. A simple exclusion
process has proven to be very useful in ex- plaining the properties of several
artificial and biological nano-channels. It is particularly useful for modeling
the influence of inter-particle interactions on transport characteristics. In
this paper, we explore several models of the exclusion process using a mean
field approach and computer simulations. We examine the effects of crowding
inside the channel and its immediate vicinity on the mean flux and the
transport times of single molecules. Finally, we discuss the robustness of the
theory's predictions with respect to the crucial characteristics of the
hindered diffusion in nano-channels that need to be included in the model.
