Polymer Physics Experiments with Single DNA Molecules

affine deformation approximately bead behavior birefringence Brownian motion calculated chain length Chem concentration configuration conformation contour length D. E. Smith data sets diffusion coefficient drag coefficient dumbbell dumbbell model elongational flow entangled polymer equilibrium experimental experiments extension versus flexible polymer fluctuations fluid flow fluorescence microscopy fluorescently labeled folded free draining function hydrodynamic drag hydrodynamic interactions images increased kinked linear loop Macromolecules measured mg/ml microscope microsphere molecular monomers Newtonian Fluid Non-Newtonian Fluid observed optical tweezers P. G. de Gennes persistence length Phys plotted polymer chain polymer dynamics polymer physics polymer solutions predicted R. G. Larson radius of gyration random coil random walk relaxation reptation model rheological scaling exponent Science shear flow shown in Fig simulations single DNA molecules solvent strain rate stretching studied T. T. Perkins test chain theoretical tube tube-like motion velocity gradient viscosity worm-like chain Zimm model µg/ml µm/s