Národní úložiště šedé literatury Nalezeno 27 záznamů.  1 - 10dalšíkonec  přejít na záznam: Hledání trvalo 0.00 vteřin. 
Study of electrochemical behaviour of cinchona alkaloids at boron doped diamond electrode
Brunovská, Veronika ; Schwarzová, Karolina (vedoucí práce) ; Sokolová, Romana (oponent)
V tejto štúdii bola použitá anodicky oxidovaná bórom dopovaná diamantová elektróda (BDD) na zistenie elektrochemických vlastností a možností stanovenia chinolínu a jeho derivátu chinínu v anodickej oblasti vo vodnom prostredí a to využitím metód cyklickej voltampérometrie (CV), square wave voltampérometrie (SWV) a adsorpčnej rozpúšťacej square wave voltampérometrie (SWAdSV). Pomocou SWV bolo zistené, že chinolín poskytoval jeden výrazný signál v BR pufri v rozmedzí pH 3,0 až 12,0. Chinín poskytoval jeden signál v rozmedzí pH 2,0 až 5,0, potom sa s narastajúcou hodnotou pH tento pík vyvíjal v dva až štyri menej výrazne signály, tj. mechanizmus oxidácie je ovplyvnený prítomnosťou chinuklidového kruhu či funkčnými skupinami na chinolinovom skelete v štuktúre chinínu. Pomocou cyklickej votlampérometrie, bolo zistené, že elektródový dej chinolínu je riadený difúziou. V prípade chinínu sa nedá všeobecne odvodiť, či je jeho oxidácia riadená difúziou či adsorpciou. Metóda SWV v prostredí BR pufru s pH 5,0 bola optimalizována pre chinolín a s použitím optimalizovaných parametrov (Estep = 5 mV; f = 40 Hz a A = 50 mV) bola zistená lineárna závislosť výšky píkov prúdu chinolínu na jeho koncentrácii v rozmedzí 1∙10-7 až 1∙10-4 mol.l-1 s limitom detekcie 3,53∙10-7 mol.l-1 . V prípade chinínu v rozmedzí...
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.
Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů
Švecová, H. ; Sokolová, Romana ; Součková, J. ; Skopalová, J. ; Barták, P.
Lipidové membrány jsou již mnoho let studovány jako modely biomembrán. Formování lipidových membrán na povrchu pevných elektrod poprvé popsali Tien a Salamon 1. Od té doby byly použity jako substráty pro lipidové vrstvy různé materiály jako např. stříbro 2, zlato 3, rtuť 4 nebo skelný uhlík 5. Lipidový film na povrchu elektrody je schopen akumulovat organické molekuly v závislosti na jejich náboji a na jejich hydrofilním respektive hydrofobním charakteru. Je známé, že mnoho organických látek, jako jsou pesticidy, léčiva a jiné farmakologicky významné látky, interagují s fosfolipidovou vrstvou a mastnými kyselinami v membráně a mohou být silně akumulovány v lipidové tkáni.
Voltammetric Behavior of Explosive Potassium Salt of 2,4-Dinitrobenzofuroxan\non Electrodes with Mercury Surface
Šelešovská, R. ; Sokolová, Romana ; Matyáš, R. ; Janíková, L.
Voltammetric behavior of potassium salt of 2,4-dinitrobenzofuroxan (KDNBF) has been\nfirstly studied using hanging mercury drop electrode (HMDE) and silver solid amalgam\nelectrode (AgSAE). Cyclic voltammetry was applied for the measurements of dependences on\npH and scan rate required for the elucidation of the ongoing electrode reactions and\ndifferential pulse voltammetry served for the development of sensitive method for KDNBF\ndetermination.
Oxidation of Bioflavonoids in Respect to their Chemical Structure
Sokolová, Romana ; Ramešová, Šárka ; Kocábová, Jana ; Degano, I.
The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of bioflavonoids resulted in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESI-MS/MS and HPLC-DAD.
Oxidation Mechanism of Rhamnetin, a Bioflavonoid Compound
Ramešová, Šárka ; Sokolová, Romana ; Degano, I.
The natural flavonoid rhamnetin (2-(3,4-dihydroxyfenyl)-3,5-dihydroxy-7-methoxychromen-4-one) is important bioactive compound. Rhamnetin was studied in aqueous solution by electrochemical methods. The oxidation mechanism proceeds in sequential steps, which correspond to the hydroxyl oxidation of groups in the three aromatic rings. The study is based on in situ spectroelectrochemistry and identification of products by HPLC-DAD and HPLC–ESI MS/MS.
Charge Transport in Single Molecule Junctions of Spirobifluorene Scaffold
Hromadová, Magdaléna ; Kolivoška, Viliam ; Sokolová, Romana ; Šebera, Jakub ; Mészáros, G. ; Valášek, M. ; Mayor, C.
Single molecule conductance of two spirobifluorene molecules of different length have been studied by scanning tunneling break junction (STM–BJ) methodology. First molecule contains a tripodal spirobifluorene platform, whereas a second one contains the same platform with chemically attached p-phenyleneethynylene molecular wire. The conductance values change only slightly between these two molecules, which demonstrated that such a platform provides both highly conducting pathway and stable anchor for the future molecular electronic devices.
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.
Comparison of Techniques for Single-Molecule Conductance Measurements of Expanded Pyridinium Molecules
Lachmanová, Štěpánka ; Hromadová, Magdaléna ; Sokolová, Romana ; Kocábová, Jana ; Gasior, Jindřich ; Mészáros, G. ; Lainé, P. P.
This work is focused on the comparison of two techniques of single-molecule conductance measurements: Scanning Tunneling Microscopy Break Junction technique and Mechanically Controlled Break Junction technique. The structure of studied compound 9-(pyridin-4-yl)benzo[c]benzo[1,2]quinolizino[3,4,5,6-ija][1,6]naphthyridin-15-ium allows the formation of the molecular bridge between two gold electrodes, which are connected to a source of the constant voltage in both of the used methods. The differences, advantages and disadvantages of both of the techniques will be discussed. Both techniques provided two values of conductance of studied compound depending on the experimantal conditions.

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