Figure 6.

The enhancement of DNA translocation time $\tau /{\tau }_{\overline{C}}$, where τ is the translocation time under salt gradient and ${\tau }_{\overline{C}}$ is that within homogeneous salt solution, as a function of salt gradient C_c/Ct. Here $\overline{C}=\left(C_c+C_t\right)/2$. For the bottom-left coordinate, C_t is kept at 1 M while C_c is tuned from 1 to 0.1 M; for the top-right coordinate, C_c is kept at 0.1 M while C_t is tuned from 0.1 to 0.8 M. (Inset) DNA speed as a function of homogeneous salt concentration.