Rods, rigid diffusion modes

Schmitz and Lu (12) have also considered coupling of translational and rotational modes for rigid rods in congested solutions as an explanation for the extraordinary diffusion regime. They concluded that, for 350 bp dinucleosomal DNA, the coupled ion model gave better agreement with the data. Since our DNA molecules are even shorter, 150 bp, the coupled translation -rotation model can seemingly be ruled out. 

Besides polydispersity effects, which are neglected in the following discussion, internal modes of motion for flexible polymers, rotational diffusion for rigid rods, hydrodynamic interaction and long range intermolecular potentials may cause the partly pronounced q-dependence of D,pp(q). 

---