Sat, 26 Jul 2008 06:11:49 BST CiteULike: dchen's Ganesan http://www.citeulike.org/user/dchen/author/Ganesan CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2763281 <i>Physical Review Letters, Vol. 100, No. 12. (2008)</i><br /><br />Applications of probe diffusion in polymer matrices typically envision that for particles sizes (R) larger than the correlation length of the polymer solution (), the probe (at long times) diffuses as in a continuum polymer solution. We present simulation results for probe diffusion in rod solutions which challenge this conventional wisdom and indicate a new mechanism of a probe diffusion operative for R>. Our simulation results are rationalized by scaling arguments invoking a novel mechanism of the constraint release motion of the rods, and suggest that the dynamical characteristics of the polymer matrix also proves important in developing a complete description of the probe motion. Dynamics of Probe Diffusion in Rod Solutions Victor Pryamitsyn Venkat Ganesan doi:10.1103/PhysRevLett.100.128302 Physical Review Letters, Vol. 100, No. 12. (2008) 2008-05-07T00:55:39-00:00 2008 Physical Review Letters 100 12 APS diffusion dynamics rod tracer http://www.citeulike.org/user/dchen/article/822246 <i>Physical Review Letters, Vol. 79, No. 17. (27 October 1997), 3282.</i><br /><br />We present a new method for measuring the linear viscoelastic shear moduli of complex fluids. Using photodiode detection of laser light scattered from a thermally excited colloidal probe sphere; we track its trajectory and extract the moduli using a frequency-dependent Stokes-Einstein equation. Spectra obtained for polyethylene oxide in water are in excellent agreement with those found mechanically and using diffusing wave spectroscopy. Since only minute sample volumes are required; this method is well suited for biomaterials of high purity; as we demonstrate with a concentrated DNA solution. Particle Tracking Microrheology of Complex Fluids TG Mason K Ganesan JH van Zanten D Wirtz SC Kuo doi:10.1103/PhysRevLett.79.3282 Physical Review Letters, Vol. 79, No. 17. (27 October 1997), 3282. 2006-08-30T16:25:45-00:00 1997 Physical Review Letters 79 17 3282 American Physical Society mason microrheology technique