National Repository of Grey Literature 133 records found  beginprevious95 - 104nextend  jump to record: Search took 0.01 seconds. 
Voltammetric determination of 4-nitrophenol and 5-nitrobenzimidazole on different amalgam electrodes
Deýlová, D. ; Barek, J. ; Josypčuk, Bohdan
Voltammetric determination of 4-nitrophenol (4-NF) and 5-nitrobenzimidazole (5-NBIA) on different amalgam electrodes.
The Electrochemistry of Natural Pigments
Sokolová, Romana ; Degano, I. ; Hromadová, Magdaléna ; Pospíšil, Lubomír
The electrochemical properties of flavonoid compounds (hemotoxylin, quercetin) were studied in buffered aqueous and non-aqueous solutions. The role of the preceding protonation/deprotonation on the electron transfer was estimated. The absorption spectra of these compounds, which contain a chromophore, were recorded during their oxidation. The electrochemical techniques were combined with GC-MS analysis in order to identify the degradation products. The mechanism of the formation of degradation products will be discussed.
Electrochemical characterization of water soluble fullerenes
Kocábová, Jana ; Gál, Miroslav ; Hromadová, Magdaléna ; Pospíšil, Lubomír
Fullere (C60) is a highly hydrophobic compound and it is considered to be insoluble in water. Different approaches were described for preparing aqueous solutions of C60. One of the possibilities is to create an inclusion complex of the C60 inside a cavity of gamma-cyclodextrin. Recently, we have shown that such complexes are capable of the electrochemical conversion of N2 to ammonium ions.
XXIX. Modern electrochemical methods
Barek, J. ; Navrátil, Tomáš
International conference XXIX. Modern electrochemical methods in Jetřichovice.
Some New Approaches to the Characterization of the Carbon Paste Electrodes
Mikysek, T. ; Švancara, I. ; Ludvík, Jiří ; Vytřas, K. ; Kalcher, K.
Uhlíkové pastové elektrody mají dvě hlavní výhody: jejich povrch lze snadno reprodukovatelně obnovovat a dále, je možné je modifikovat v objemu za účelem získání specifických senzorů. Příprava těchto elektrod však závisí jednak na použitých materiálech, tedy na uhlíkovém prášku i na olejovém médiu, jednak na jejich vzájemném poměru. To umožňuje velikou variabilitu vlastností, současně ale otázka charakterizace těchto elektrod je velmi významná. Bylo zjištěno, že graf závislosti odporu elektrody na jejím složení je ve tvaru dvou protínajících se přímek. K vysvětlení této závislosti byl navržen, testován a diskutován model vycházející z představy těsně uspořádaných koulí (známé z krystalografie). Další způsob charakterizace těchto elektrod je založen na interpretaci cyklických voltamogramů nějakého dobře reverzibilního systému. Obě tyto metody jsou kompatibilní, navíc umožňují vysvětlení dalších jevů spojených s morfologií a se stárnutím těchto elektrod.
Intramolekulární elektronová interakce dvou typů dikarbonylových slouočenin a jejich derivátů – elektrochemická a kvantově chemická studie
Ludvík, Jiří ; Celik, H. ; Jirkovský, Jaromír ; Zuman, P.
In the frame of studies of molecules with two redox centers, two isomeric monooximes derived from aryl-alkyl 1,2-diketones were electrochemically investigated. Whereas 1-phenyl-2-oxo-1-oximinopropane is reduced in acidic media according to the mechanism typical for oximes, that means by fou electrons yielding aminoketone, which is further reduced bielectronically under splitting of ammonia, its isomer 1-phenyl-1-oxo-2-oximinopropane is reduced to the stable 1-hydroxy-2-aminoolefine (enol form) and this corresponds to the reduction mechanism of benzil. It is surprising that the unsymmetric molecule behaves like the symmetric one. Basing on the electrochemical data and their correlation with quantum chemical calculations it was possible to explain this phenomenon.
Electrochemistry at the interface between two electrolyte solutions – a tool to modelling of biological cell membranes
Mareček, Vladimír ; Štulík, K.
It is demonstrated that the phospholipid modified interfaces can serve as simple models for certain interactions occurring at biological cell membranes. One of the most important aspects of such studies is the formation and behaviour of a phospholipid membrane at the interface. A five-step mechanism has been proposed for the lecithin adsorption/desorption process, involving sorption, acid-base and association/dissociation interactions.
Electrochemical study of degradation of natural dyes used in artworks
Sokolová, Romana ; Degano, I. ; Hromadová, Magdaléna
This work is focused on the electrochemical study of natural flavonoid dyes used in artworks. Electrochemical behaviour of hematoxylin was studied in 0.1 M KCl, phosphate buffers of pH 5 – 12 and in acetonitrile. The mechanism of oxidation and the stability of intermediates as a function of pH are discussed. The electrochemical techniques are combined with spectrophotometry, LC/DAD and GC-MS analysis in order to identify the degradation products.
Electrochemical nitrogen fixation in the presence of fullerene -.gamma.-cyclodextrin complex
Kocábová, Jana ; Gál, Miroslav ; Hromadová, Magdaléna ; Pospíšil, Lubomír
We report on the electrochemical conversion of dinitrogen to ammonia at ambient pressure and 60oC mediated by reduced fullerene (C60) inside a molecular cavity of .gamma.-cyclodextrin (.gamma.-CD) in aqueous solution.

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