Gas-phase normal mode analyses, that have been used to study the frequencies and amplitudes of collective motions in macromolecules, have been generalized to the liquid phase where frictional forces play a important role. Within the framework of the Langevin equation, the problem has been reduced to solving an eigenvalue equation involving supermatrix constructed from the force constant and friction matrices and computationally convenient expressions have been obtained for the relevant experimentally accessible correlation functions. Preliminary calculations indicate that this approach provides a viable means of determining the influence of solvent on the dynamics of collective motions in macromolecules. The transient electric birefringence (TEB) of polyelectrolytes such as DNA, reflects not only the rotational motion of the macroions but also the dynamics of the surrounding ion atmosphere. By correctly treating the coupling between the rotational and counterion dynamics, rigorous expressions for the TEB when an external electric fields is turned on, reversed or oscillates were obtained and used to successfully analyze recent experimental data on short DNA restriction fragments. The theory of the current to microelectrodes with band and ring geometries has been developed and applied to the analysis of electrochemical measurements using such devices.
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