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Supported Phospholipid Bilayer at the Conductive Interface
Sokolová, Romana ; Kocábová, Jana ; Kolivoška, Viliam ; Gál, M.
The interactions of ethanol and flavonoid compounds with supported phospholipid bilayer\nwere studied by means of electrochemical methods and scanning probe techniques. The\nstability of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) phospholipid bilayer\nsupported on different types of conductive substrate was investigated. The relationship\nbetween the method of lipid deposition and the formation of several types of lipid structures\nincluding vesicles, hemimicelles, patches and single bilayers on the interface is discussed.
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2-D simulations of electromigration processes
Kolivoška, Viliam ; Koval, Dušan (referee) ; Gaš, Bohuslav (advisor)
6 Abstract In the presented thesis we introduce a computational model that can be used for 2-D and 3-D computer simulations of experiments in electrophoresis. The simulations are carried out by the aid of the finite element method (FEM). In particular, commercially available program Comsol Multiphysics 3.3 is employed. A general shape of continuity equation is chosen to express the mass, electric charge, momentum and energy conservation law. Diffusion, migration and convection terms are taken into account when formulating the mass conservation law. Both external (driving voltage) and internal (diffusion currents) terms are considered in the electric charge conservation law. Both constant voltage mode and constant current mode can be handled. A solvent is regarded as an incompressible Newtonian fluid. Both pressure-driven and electroosmotic flows can be taken into consideration. The heat convection as well as the heat diffusion is governed by the energy conservation law. Both strong and weak electrolytes (of any attainable valency) may be regarded as system constituents. Furthermore, the model can handle the ionic strength correction if desired. A task may be assigned either in Cartesian or cylindrical coordinates. The presented model was employed to solve four particular tasks. The first one inspects the...
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Dependence of Single-Molecule Conductance of Pyridinium Derivatives on Their Structure
Lachmanová, Štěpánka ; Hromadová, Magdaléna ; Kolivoška, Viliam ; Pospíšil, Lubomír ; Gasior, Jindřich ; Mészáros, G. ; Lainé, P. P.
The derivates of pyridinium belong to promising group of molecules applicable in molecular electronics. For this purpose, four expanded branched pyridinium compounds were synthetized and the influence of the molecular structure on their electrochemical properties and single-molecule conductances has been studied. The highest values of conductance provided compounds 9-(pyridin-4-yl)benzo[c]benzo[1,2]quinolizino[3,4,5,6-ija][1,6]naphthyridin-15-ium tetrafluoroborate and 3,5-dimethyl-2´,6´-diphenyl-[4,1´:4´,4´´-terpyridin]-1´-ium tetrafluoroborate. By the electrochemical reduction both of these compounds received two electrons in two separated one-electron steps. On the other hand, the compounds 2´,6´-diphenyl-[4,1´:4´,4´´-terpyridin]-1´-ium tetrafluoroborate and 2,6-diphenyl-4-(4-(pyridin-4-yl)phenyl)-[1,4´-bipyridin]-1-ium tetrafluoroborate are reduced by different mechanism and their conductance was lower.
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Reduction and Oxidation of Hydroxyquinolines in Acetonitrile and Dimethylsulfoxide
Sokolová, Romana ; Ramešová, Šárka ; Fiedler, Jan ; Kolivoška, Viliam ; Degano, I. ; Gál, M. ; Szala, M. ; Nycz, J. E.
This study is focused on investigation of oxidation and reduction pathways of selected hydroxyquinoline compounds in nonaqueous solutions. The experimentally obtained reduction potentials are reported to well correlate with calculated values of LUMO energies as well as the obtained oxidation potentials are in a good agreement with theoretical HOMO energies. The cyclic voltammetry, in situ UV/Vis spectroelectrochemistry and in situ IR spectroelectrochemistry confirmed that the oxidation mechanism is complicated. Oxidation unexpectedly proceeds together with protonation of the starting compound. This behaviour was found for all studied compounds, hydroxyquinoline carboxylic acids and also for compounds, where a methyl group is present instead of carboxylic group.
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