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The entropic forces on the self-retracting granular chains, which are confined in channels with different widths, are determined. The time dependence of the length of chain remaining in the channel Lin(t) is measured. The entropic force is treated as the only parameter in fitting the solution of the nonlinear equation of motion of Lin(t) to the experimental data. The dependence of the entropic force on the width of the confining channel can be expressed as a power-law with an exponent of 1.3, which is consistent with the previous theoretical predictions for the entropy loss due to confinement. [ABSTRACT FROM AUTHOR]

The kinetics of the collapse of the coil state into condensed states is studied with vibrated granular chain composed of N metal beads partially immersed in water. The radius of gyration of the chain, Rg is measured. For short chains (N < 140), disk-like condensed state is formed and Rg decreases with time such that the function ΔRg2 (≡ Rg2 - Rg2(∞)) = A e-t/τ, where the relaxation time τ follows a power-law dependence on the chain length N with an exponent γ = 1.9 ± 0.2. For the chains with length N ≥ 300, rod-like clusters are observed during the initial stage of collapse and Rg2 = Rg2(0) - Btβ, with β = 0.6 ± 0.1. In the coarsening stage, the exponential dependence of ΔRg2 on time still holds, however, the relaxation time τ fluctuates and has no simple dependence on N. Furthermore, the time dependence of the averaged radius of gyration of the individual clusters, Rg,cl can be described by the theory of Lifshitz and Slyozov. A peak in the structure function of long chains is observed in the initial stage of the collapse transition. The collapse transition in the bead chains is a first order phase transition. However, features of the spinodal decomposition are also observed. [ABSTRACT FROM AUTHOR]

The effects of gate voltage on the translocation of DNA molecules through a nanopore are studied. A twenty-fold increase in the translocation time is observed with a positive gate voltage applied, without changing too much of the ionic current. The amplitude of the current blockage by the DNA molecules was reduced by roughly the same factor. At the same time, the number of the blocking events decreases significantly. The applied gate voltage also modulates the scatter plot of the amplitude of the current blockage against the dwell time. The observations are consistent with the recent theoretical results. [ABSTRACT FROM AUTHOR]

The electronic conduction through the self-assembled monolayer (SAM) can be modulated by the electric potential applied to the silicon gate electrode surrounding the SAM. The dependence of the current through SAM on the gate voltage can be explained that the renormalized molecular energy levels are swept through the window between the Fermi levels of the source and drain electrodes. The effects of the lowest unoccupied molecular orbital and a hybrid energy level near the Fermi level in the transmission spectrum can be identified. [ABSTRACT FROM AUTHOR]