纳米孔单分子传感器电导特性有限元分析

主要从纳米孔结构角度,考虑生物分子在纳米孔内的位阻效应影响。运用有限元模拟方法分别模拟了3类常见纳米孔的电导,并比较了3种不同纳米孔在检测纳米杆通过纳米孔时的相对堵塞电流值大小。研究了纳米杆上带有亚结构时,在3种纳米孔内的电流堵塞效应的差异。研究方法有助于进一步理解纳米孔结构对检测生物分子的影响。

Effect of salt gradients on DNA translocation through solid-state nanopores

Aiming at the issues of controlling the translocation speed of DNA through a solid-state nanopore and enlarging the signal-to-noise ratio of ionic current modulation, which are challenges for the application of nanopore technology in DNA detection, salt concentration gradients are applied across the nanopore to investigate their influence on the DNA translocation time and signal-to-noise ratio. Experimental data demonstrates that, in symmetric concentration conditions, both the current blockade and dwell time for A-DNA translocation through a solid-state nanopore increase along with potassium chloride concentration. When the concentration in the trans chamber is decreased from 1 to 0.1 mol/L, keeping the concentration of the cis chamber at 1 mol/L, the normalized current blockade is found to be increased by one order. The increased dwell time and enhanced signal-to-noise ratio are achieved with salt gradients across the nanopore, which can improve the sensitivity when detecting DNA samples.

Current blockade mechanism for DNA translocation through solid-state nanopore with different membrane thickness

The current blockade mechanism for λ -DNA translocation under electrical field is investigated through solid-state nanopores with different pore thicknesses. The conductance of a nanopore system mainly consists of the contribution of the pore and access region, and the latter becomes dominant when the nanopore thickness gradually decreases to atomic layer thickness. Based on the existing model of nanopore resistance, a simplified model which describes the relative current blockade during the X-DNA translocation through the nanopores is deduced to quantitatively present the relationship between nanopore thickness and relative current blockade. Results show that the relative current blockade is effectively increased by reducing the nanopore diameter but it decreases with the decreasing nanopore thickness. A two-stage schematic is proposed to increase the relative current blockade by setting a much smaller resistance region. Experimental results show a 21. 9% increase in the relative current blockade with the proposed schematic.

Jam Formation of Traffic Flow in Harbor Tunnel

This paper reports a study concerning occurrence and growth of traffic jam in a harbor tunnel. The single-lane with three sections （downgrade, fiat, and upgrade） is taken into account and they are characterized with different velocity limit. At the low density, the traffic current increases linearly with density and saturates at some values of immediately density. As the density increases, the traffic jam appears firstly before the upgrade section and then extends to the downgrade section. Additionally, the relationships of the velocity and headway against position in different densities are obta/ned from simulation. These results clearly clarify where and when the traffic jam appears. Finally, the critical densities are derived via the theoretical analysis before and after the discontinuous fronts and the theoretical results are consistent with the critical values of simulation results.