No abstract

No abstract

No abstract

We have modeled the generation of a voltage signal in noncontact potentiometric scanning force microscopy for a locally enhanced potential due to an isolated patch of electrostatic charge on an insulating surface. Both the distribution of the charge and the dielectric nature of the insulator is taken into account. When the charge is assumed to disperse ohmically on the surface, a complex time-dependent decay in the signal occurs. The profile of the decay predicted by this assumption has a shape similar to that observed experimentally in submicron scale contact charging experiments.

We report a single-molecule-based analysis of strand breakages on large DNA molecules induced by an atmospheric pressure plasma jet. We exposed DNA solution to an argon plasma jet; single-molecule observation that involved molecular combing was then used to measure the length of individual DNA molecules. The measured DNA length showed that plasma exposure caused a marked change in length of DNA molecules. The rate of plasma-induced strand breakage on large random-coiled DNA molecules was determined using a simple mathematical model. For strand breaks on large DNA molecules the rate was estimated.