Sun, 27 Jul 2008 07:55:54 BST CiteULike: dchen's defect http://www.citeulike.org/user/dchen/tag/defect CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2883886 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 2. (2007)</i><br /><br />Point defects are ubiquitous in two-dimensional crystals and play a fundamental role in determining their mechanical and thermodynamical properties. When crystals are formed on a curved background, finite-length grain boundaries (scars) are generally needed to stabilize the crystal. We provide a continuum elasticity analysis of defect dynamics in curved crystals. By exploiting the fact that any point defect can be obtained as an appropriate combination of disclinations, we provide an analytical determination of the elastic spring constants of dislocations within scars and compare them with existing experimental measurements from optical microscopy. We further show that vacancies and interstitials, which are stable defects in flat crystals, are generally unstable in curved geometries. This observation explains why vacancies or interstitials are never found in equilibrium spherical crystals. We finish with some further implications for experiments and future theoretical work. Dynamics and instabilities of defects in two-dimensional crystals on curved backgrounds Mark Bowick Homin Shin Alex Travesset doi:10.1103/PhysRevE.75.021404 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 2. (2007) 2008-06-11T21:47:51-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 75 2 APS 2007 2d crystal defect pre http://www.citeulike.org/user/dchen/article/2811046 <i>Phys. Rev. Lett. 100, 197802 (2008)</i><br /><br />We perform large-scale Monte Carlo simulations of orientational ordering in nematic shells and study the type and position of topological defects when an external electric field (homogeneous or quadrupolar) is applied. The field-induced variation of the defect number (and strength) can be used to change the valence of colloidal particles coated with a nematic layer. Controlling Surface Defect Valence in Colloids G Skačej C Zannoni Phys. Rev. Lett. 100, 197802 (2008) 2008-05-18T18:56:52-00:00 Phys. Rev. Lett. 100, 197802 (2008) 2008 colloids control defect liquidcrystal http://www.citeulike.org/user/dchen/article/2791741 <i>Physical Review Letters, Vol. 97, No. 12. (2006)</i><br /><br />We numerically study many-body interactions among colloidal particles suspended in a nematic liquid crystal, using a fluid particle dynamics method, which properly incorporates dynamical coupling among particles, nematic orientation, and flow field. Based on simulation results, we propose a new type of interparticle interaction in addition to well-known quadrupolar interaction for particles accompanying Saturn-ring defects. This interaction is mediated by the defect of the nematic phase: upon nematic ordering, a closed disclination loop binds more than two particles to form a sheetlike dynamically arrested structure. The interaction depends upon the topology of a disclination loop binding particles, which is determined by aggregation history. Colloidal Aggregation in a Nematic Liquid Crystal: Topological Arrest of Particles by a Single-Stroke Disclination Line Takeaki Araki Hajime Tanaka doi:10.1103/PhysRevLett.97.127801 Physical Review Letters, Vol. 97, No. 12. (2006) 2008-05-13T00:24:02-00:00 2006 Physical Review Letters 97 12 APS 2006 colloids defect interaction liquidcrystal simulation tanaka http://www.citeulike.org/user/dchen/article/2759114 <i>Physical Review Letters, Vol. 100, No. 17. (2008)</i><br /><br />The full 2D analysis of roughness profiles of fracture surfaces resulting from quasistatic crack propagation in gelatin gels reveals an original behavior characterized by (i) strong anisotropy with maximum roughness at V-independent symmetry-preserving angles and (ii) a subcritical instability leading, below a critical velocity, to a cross-hatched regime due to straight macrosteps drifting at the same magic angles and nucleated on crack-pinning network inhomogeneities. Step height values are determined by the width of the strain-hardened zone, governed by the elastic crack blunting characteristic of soft solids with breaking stresses much larger than low strain moduli. Magic Angles and Cross-Hatching Instability in Hydrogel Fracture T Baumberger C Caroli D Martina O Ronsin doi:10.1103/PhysRevLett.100.178303 Physical Review Letters, Vol. 100, No. 17. (2008) 2008-05-05T20:13:26-00:00 2008 Physical Review Letters 100 17 APS defect gel interface structure http://www.citeulike.org/user/dchen/article/2754601 <i>Physical Review Letters, Vol. 96, No. 20. (2006)</i><br /><br />We report on the observation of an anomalously high damping measured by a vibrating-wire resonator (VWR) immersed into superfluid 3He-B at ultralow temperatures. The observed dissipation is orders of magnitude above that corresponding to friction with the dilute normal fraction and superfluid vortices. A clear pinning behavior is also observed, as well as a strong magnetic field dependence. Our analysis points to the interaction of the VWR with a planar topological defect, analogue to cosmological vacua defects, as proposed by Salomaa and Volovik. Probing “Cosmological” Defects in Superfluid [sup 3]He-B with a Vibrating-Wire Resonator CB Winkelmann J Elbs Yu H Godfrin doi:10.1103/PhysRevLett.96.205301 Physical Review Letters, Vol. 96, No. 20. (2006) 2008-05-04T22:37:24-00:00 2006 Physical Review Letters 96 20 APS 2006 defect focus quench http://www.citeulike.org/user/dchen/article/2746695 <i>(2006)</i> Dynamics of dislocations in thin colloidal crystals Cohen Schall Weitz (2006) 2008-05-02T17:54:23-00:00 2006 cohen colloid defect schall weitz http://www.citeulike.org/user/dchen/article/553502 <i>Nature, Vol. 440, No. 7082., pp. 319-323.</i> Visualizing dislocation nucleation by indenting colloidal crystals Peter Schall Itai Cohen David Weitz Frans Spaepen doi:10.1038/nature04557 Nature, Vol. 440, No. 7082., pp. 319-323. 2006-03-15T23:36:35-00:00 Nature 0028-0836 440 7082 319 323 Nature Publishing Group defect schall shear weitz http://www.citeulike.org/user/dchen/article/2683304 <i>Physical Review Letters, Vol. 99 (2007)</i> Novel Defect Structures in Nematic Liquid Crystal Shells Fernández-Nieves Physical Review Letters, Vol. 99 (2007) 2008-04-17T19:44:27-00:00 2007 Physical Review Letters 99 2007 atlanta defect liquidcrystal weitz