Mon, 07 Jul 2008 00:23:01 BST CiteULike: di dchen Likos http://www.citeulike.org/user/dchen/author/Likos CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2767397 <i>Physical Review Letters, Vol. 100, No. 11. (2008)</i><br /><br />Optical tweezers are employed to measure the forces of interaction within a single pair of DNA-grafted colloids, dependent on the molecular weight of the DNA chains, and the concentration and valence of the surrounding ionic medium. The resulting forces are short range and set in as the surface-to-surface distance between the colloidal cores reaches the value of the brush height. The measured force-distance relation is analyzed by means of a theoretical treatment that quantitatively describes the effects of compression of the chains on the surface of the opposite-lying colloid. Quantitative agreement with the experiment is obtained for all parameter combinations. Polyelectrolyte-Compression Forces between Spherical DNA Brushes Kati Kegler Martin Konieczny Gustavo Espinosa Christof Gutsche Matthias Salomo Friedrich Kremer Christos Likos doi:10.1103/PhysRevLett.100.118302 Physical Review Letters, Vol. 100, No. 11. (2008) 2008-05-07T21:14:58-00:00 2008 Physical Review Letters 100 11 APS biology colloids interaction opticaltweezer http://www.citeulike.org/user/dchen/article/2552923 <i>Physical Review Letters, Vol. 99, No. 10. (2007)</i><br /><br />For a large class of fluids exhibiting ultrasoft bounded pair potentials, particles form crystals consisting of clusters located in the lattice sites, with a density-independent lattice constant. Here we present an investigation on the dynamic features of a representative example of this class. It is found that particles can diffuse between lattice sites, maintaining the lattice structure, through an activated hopping mechanism. This feature yields finite values for the diffusivity and full relaxation of density correlation functions. Simulations suggest the existence of a localization transition which is avoided by hopping and a dynamic decoupling between self- and collective correlations. Diffusion and Relaxation Dynamics in Cluster Crystals Angel Moreno Christos Likos doi:10.1103/PhysRevLett.99.107801 Physical Review Letters, Vol. 99, No. 10. (2007) 2008-03-18T20:36:27-00:00 2007 Physical Review Letters 99 10 APS 2007 diffusion foam http://www.citeulike.org/user/dchen/article/2547832 <i>Physical Review Letters, Vol. 100, No. 10. (2008)</i><br /><br />We study the conditions under which and how an imposed cluster of fixed colloidal particles at prescribed positions triggers crystal nucleation from a metastable colloidal fluid. Dynamical density functional theory of freezing and Brownian dynamics simulations are applied to a two-dimensional colloidal system with dipolar interactions. The externally imposed nucleation clusters involve colloidal particles either on a rhombic lattice or along two linear arrays separated by a gap. Crystal growth occurs after the peaks of the nucleation cluster have first relaxed to a cutout of the stable bulk crystal. Colloidal Crystal Growth at Externally Imposed Nucleation Clusters Sven van Teeffelen Christos Likos Hartmut Löwen doi:10.1103/PhysRevLett.100.108302 Physical Review Letters, Vol. 100, No. 10. (2008) 2008-03-17T22:23:57-00:00 2008 Physical Review Letters 100 10 APS 2008 2d colloids cool crystal