报告题目：DNA在交变电场中的收缩现象

　　Title: Collapse of DNA in ac Electric Fields

　　报告人：Dr. Zhou Chunda (Detector Scientist in Nabsys Inc. )

　　时间：2018年1月29日（星期一）15：00

　　地址：近代物理所5号楼1008会议室

　　摘要：通常的DNA理论预计DNA在聚电解质中不会发生收缩的现象。而我们在交变电场中却观察到了DNA的收缩，完全无法用之前的理论解释。我们通过数值模拟对此现象进行了解释。报告还介绍了发现的过程和采用的实验。

　　Abstract

　　We report that double-stranded DNA collapses in the presence of ac electric fields at frequencies of a few hundred Hertz, and does not stretch as commonly assumed. In particular, we show that confinement-stretched DNA can collapse to about one quarter of its equilibrium length. We propose that this effect is based on finite relaxation times of the counterion cloud, and the subsequent partitioning of the molecule into mutually attractive units. We discuss alternative models of those attractive units.