Elastic Theory of Defects in Toroidal Crystals

We report a comprehensive analysis of the ground state properties of axisymmetric toroidal crystals based on the elastic theory of defects on curved substrates. The ground state is analyzed as a function of the aspect ratio of the torus, which provides a non-local measure of the underlying Gaussian curvature, and the ratio of the defect core-energy to the Young modulus. Several structural features are discussed,including a spectacular example of curvature-driven amorphization in the limit of the aspect ratio approaching one. The outcome of the elastic theory is then compared with the results of a numerical study of a system of point-like particles constrained on the surface of a torus and interacting via a short range potential.Comment: 24 pages, 24 figure

MAGNETIC-FIELD-INDUCED ALIGNMENT AND INSTABILITIES IN ORDERED COLLOIDS OF TOBACCO MOSAIC VIRUS

Nous utilisons des champs magnétiques pour orienter des cristaux liquides nématiques ainsi que des solutions cristallines colloïdales monodisperses de virus du tabac (TMV). Les instabilités hydrodynamiques induites par les réorientations sous champ magnétique ont été étudiées sur des cristaux liquides nématiques bien orientés.Magnetic fields have been used to produce well aligned nematic liquid crystalline and colloidal crystalline samples of nearly monodisperse tobacco mosaic virus (TMV). Hydrodynamic instabilities induced by reorientation in a magnetic field have been studied in the well aligned nematic liquid crystalline samples