Robert Repnik

• PhD
• Professor (Assistant) at University of Maribor

We study experimentally and theoretically controlled targeting of specific nanoparticles (NPs) to different regions within nematic liquid crystal. Using a simple mesoscopic Landau-de Gennes-type model in terms of a tensor nematic order parameter, we demonstrate a general mechanism which could be exploited for controlled targeting of NPs within a sp...

Physicists research numerous interesting physics problems, among them the behaviour of liquid crystals. These problems can be very useful for illustrating general principles of physics, and so we worked to include them in our natural science program. In the frame of a project entitled "Introduction of current research interdisciplinary topic into e...

Universal behavior related to continuous symmetry breaking in nematic liquid crystals is studied using Brownian molecular dynamics. A three-dimensional lattice system of rod-like objects interacting via the Lebwohl-Lasher interaction is considered. We test the applicability of predictions originally derived in cosmology and magnetism. In the first...

We study theoretically mixtures of liquid crystals (LCs) and nanoparticles (NPs) at a mesoscopic level. Orientational LC ordering is given in terms of a tensor order parameter. We estimate conditions which favor or disfavor phase separation. We show under which conditions topological defect could be exploited as trapping centers for nanoparticles....

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 e...

The two-dimensional presentation of the three-dimensional nematic liquid crystal structure can be visualized in various ways: by oriented rotational ellipsoids, bricks, cylinders, or sticks, representing either individual molecules or nematic director field. Here, we give a different approach: the three axes of Cartesian coordinate system are assig...

Understanding physical phenomena in education often requires a good three-dimensional (3D) imagination. Visualization software mainly uses either active 3D virtual simulations or static two-dimensional cross-sections for presenting real physical systems. We performed a comparative study of students’ comprehension of both visualization approaches in...

Introduction of any new technology in education is a hard job. It takes years to embed LMS to study processes. At present we have lectures for different scientific disciplines that use LMSs. LMSs have far more functions than general lecturer generally use. In the beginning they started to use LMS as data warehouse for learning material and communic...

Understanding physical phenomena often requires a comprehensive imagination of the subject. Visualization software uses two main approaches for presenting three-dimensional (3D) physical systems in two dimensions (2D): 3D virtual simulation (3D view) or 2D cross-sections (2D view). We focused on liquid crystals (LCs) in our comparative study of com...

In Slovene educational curriculum the subject Environmental education is taught from the first to the third level of primary school (pupils' age between seven and nine). The goal of this subject is not merely acquiring basic facts about the world around us; it is rather more important for students to gain specific and general competences for lifelo...

A close cooperation between editor (publisher), authors and reviewers is very important for preparation of electronic learning materials (e-learning materials) with high quality. E-learning materials require content review and evaluation of didactic suitability. They also need technical review which is less important in printed learning materials....

It is very important for the development of natural science competences of children to choose the right approach to teaching the physics. E-learning materials developed so far are a useful addition to the learning process. Their function is to assist in explaining the real world around us. Among other goals, this means the explanation of experiment...

We accept interactive technology in the production of e-learning materials. It is not perceived just as valuable addition, but it becomes mandatory in e-learning material production. Therefore all new e-learning materials are either WEB 2.0 enhanced or obsolete. But is this true? We have different types of e-learning materials. Some are for self-le...

The processing of dynamical systems from everyday life requires the development of system thinking and the record of mathematical relations between variables, which is known as mathematical modelling. The dilemma that appears is how to develop the system thinking and particularly mathematical modelling in schools at earlier ages. In order to discus...

We study the nematic structure of a liquid crystal confined within a plan-parallel cell following the temperature driven isotropic-nematic phase transition quench. The Lebwohl-Lasher lattice model is used. The kinetics of the system is followed via Brownian molecular dynamics, enabling us to reach macroscopic time scales. In the simulation we assum...

Liquid-crystal phases are typical examples of soft and complex materials that exhibit an abundance of different phenomena. In this paper we present some of our results contributing to the understanding of the physics of defects in nematic liquid crystals. The examples presented exhibit many features that are also of interest for other branches of p...

Flüssigkristalle können wie eine Flüssigkeit fließen und zugleich eine innere Ordnung besitzen, die an Festkörper erinnert. Sie begegnen uns im Alltag in vielen technischen Anwendungen, beispielsweise in Displays von elektronischen Gerten. Seit Millionen von Jahren sind sie schon zentrale Bausteine von biologischen Systemen. Dazu zhlen zum Beispiel...

Fl�ssigkristalle k�nnen wie eine Fl�ssigkeit flie�en und zugleich eine innere Ordnung besitzen, die an Festk�rper erinnert. Sie begegnen uns im Alltag in vielen technischen Anwendungen, beispielsweise in Displays von elektronischen Ger�ten. Seit Millionen von Jahren sind sie schon zentrale Bausteine von biologischen Systemen. Dazu z�h...

We performed an x-ray scattering study of the smectic A (SmA) ordering of the liquid crystal 8CB (octylcyanobiphenyl) confined to a control porous glass with a typical void radius R = 0.2 µm. The voids were either nontreated or covered with silane. The results reveal a strong influence of spatial restriction and surface treatment on the temperature...

In today's assessment of individuals in the industries and the education LMS and E-portfolios are used. Studying market available LMS we find out that they are unsuitable where three level's control is needed. This is always present in the education where we encounter teacher, tutor and students. Our problem was to solve teacher training where stud...