Samo Kralj

Bio: Samo Kralj is an academic researcher from University of Maribor. The author has contributed to research in topics: Liquid crystal & Phase transition. The author has an hindex of 31, co-authored 198 publications receiving 3370 citations. Previous affiliations of Samo Kralj include University of Ljubljana & Eindhoven University of Technology.

Thin Nematic Films: Laboratory of Physics for Topological Defects

Abstract: In this pedagogical presentation we demonstrate basic physics of topological defects in orientational ordering. We limit to two dimensional (2D) films. Different defect structures and pairs defect-antidefect are visualized in the applet presentation, which shows also the corresponding interference textures simulating typical polarizing microscopy experiment. The conservation of topological defect is shown on the case of 2D films on curved surfaces. In different geometrical shapes with the same Euler characteristics we demonstrate equilibrium (or at least relatively stable) nematic structures possessing 2 to 8 defects pairs with the winding number |M|=1/2, where the sum of all defects corresponds to Mtot = 2.

Edge Dislocations in Smectic-A Liquid Crystals

Abstract: We study theoretically static structure and annihilation dynamics of edge dislocations in a smectic-A liquid crystal confined to a plan-parallel cell The Landau-Ginzburg type phenomenological approach is used in terms of a complex order parameter We investigate a structure of an isolated dislocation that is enforced by boundary conditions We further follow the annihilation dynamics of a pair of dislocations into a defectless state

Stability and Metastability in Nematic Glasses: a Computational Study

Abstract: The influence of randomly distributed impurities on liquid crystal (LC) orientational ordering is studied using a simple Lebwohl-Lasher type lattice model in two (d=2) and three (d=3) dimensions. The impurities of concentration p impose a random anisotropy field-type of disorder of strength w to the LC nematic phase. Orientational correlations can be well presented by a single coherence length ξ for a weak enough w. We show that the Imry-Ma scaling prediction w ξ α w− /2(4 −d) holds true if the LC configuration is initially quenched from the isotropic phase. For other initial configurations the scaling is in general not obeyed.

Phase separation in confined systems

Abstract: We review the current state of knowledge of phase separation and phase equilibria in porous materials. Our emphasis is on fundamental studies of simple fluids (composed of small, neutral molecules) and well-characterized materials. While theoretical and molecular simulation studies are stressed, we also survey experimental investigations that are fundamental in nature. Following a brief survey of the most useful theoretical and simulation methods, we describe the nature of gas‐liquid (capillary condensation), layering, liquid‐liquid and freezing/melting transitions. In each case studies for simple pore geometries, and also more complex ones where available, are discussed. While a reasonably good understanding is available for phase equilibria of pure adsorbates in simple pore geometries, there is a need to extend the models to more complex pore geometries that include effects of chemical and geometrical heterogeneity and connectivity. In addition, with the exception of liquid‐liquid equilibria, little work has been done so far on phase separation for mixtures in porous media.

Effects of confinement on freezing and melting.

Abstract: We present a review of experimental, theoretical, and molecular simulation studies of confinement effects on freezing and melting We consider both simple and more complex adsorbates that are confined in various environments (slit or cylindrical pores and also disordered porous materials) The most commonly used molecular simulation, theoretical and experimental methods are first presented We also provide a brief description of the most widely used porous materials The current state of knowledge on the effects of confinement on structure and freezing temperature, and the appearance of new surface-driven and confinement-driven phases are then discussed We also address how confinement affects the glass transition

Liquid-crystal materials find a new order in biomedical applications.

Abstract: With the maturation of the information display field, liquid-crystal materials research is undergoing a modern-day renaissance. Devices and configurations based on liquid-crystal materials are being developed for spectroscopy, imaging and microscopy, leading to new techniques for optically probing biological systems. Biosensors fabricated with liquid-crystal materials can allow label-free observations of biological phenomena. Liquid-crystal polymers are starting to be used in biomimicking colour-producing structures, lenses and muscle-like actuators. New areas of application in the realms of biology and medicine are stimulating innovation in basic and applied research into these materials.