National Repository of Grey Literature 56 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
The oxidative degradation study of ticagrelor
Tonnerová, Barbora ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
Ticagrelor is a platelet aggregation inhibitor drug, used for treatment of patients with acute coronary syndrome. The only active metabolite, a reverse blocator of P2Y12 adenosindiphosphate receptor, is produced by hepatic metabolism. Ticagrelor is soluble in 50 % (vol.) methanol solution. The most efficient separation of ticagrelor using ultrahigh performance liquid chromatography turned out to be in gradient: (0-4 min: 20→80 % A; 4-6 min: 80 % A; 6-6,5 min: 80→20 % A; 6,5-8,5 min: 20 % A; A stands for acetonitrile). Mobile phase is composed of acetonitrile and ammonium acetate buffer (20 mmol·dm-3 and pH 8,0). Reverse stationary phase is Kinetex C18 100A column (100 x 2,1 mm, 1,7 µm; Phenomenex, USA). Retention time of ticagrelor is 4,91 min. The separation method was used to observe the oxidative degradation of ticagrelor. After 7 hours of exposition to hydrogen peroxide solution at 50 řC, 20 % of ticagrelor has degraded. One degradation product was formed at same speed as the degradation of ticagrelor had. Retention time of this degradation product is 3,95 min.
Voltammetric behaviour of cholesterol on glassy carbon electrode
Bláhová, Eva ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this Thesis is a study of voltammetric behaviour of cholesterol on glassy carbon electrode in the presence of acetonitrile and strong acid. The electrochemical oxidation occurs after dehydration of cholesterol induced by the acid. The study was performed using cyclic voltammetry, mostly in the presence of perchloric acid. Further, influence of other acids - sulphuric, nitric and phosphoric acid - was studied. Cholesterol provides in the presence of perchloric and sulphuric acid one anodic signal at the potential of +1400 mV vs. Ag/0,01 mol.l-1 AgNO3 in 1 mol.l-1 NaClO4 in acetonitrile. The influence of polarization rate, water content and concentration of perchloric acid in the supporting electrolyte on the oxidation signal of cholesterol was studied. Calibration dependence of cholesterol was measured using differential pulse voltammetry. The limit of detection was determined to be 4,83.10-6 mol.l-1 . Key words: Dehydration, glassy carbon electrode, cholesterol, oxidation, voltammetry
Biomimetic polymer/graphene layered nanocomposites
Dostalík, Petr ; Ondreáš, František (referee) ; Zbončák, Marek (advisor)
This batchelot thesis deals with preparation of biomimetic polymer/graphene layered nanocomposites. In order to prepare nanocomposites, it was first necessary to prepare a suitable graphene material. The Tour-Marcan method was chosen for its preparation, in which the effect of oxidation time on the structure of the resulting graphene/graphite oxide was investigated. From the result of structural analysis was evaluated, that after 4 hours of oxidation structure of graphite was intercalated, oxygen groups were formed (mainly expoxy groups) and inter-layer spacing increased to form graphite oxide (GO). Extension of oxidation time did not lead to major changes in struture of GO. Nanocomposites were prepareted by solution-casting method. The polar polymer – polyvinyl alcohol (PVAl) was used as a matrix with assumption of strong interaction between GO a PVAl. In order to promote GO intercalation, an ultrasonic dispersant was used in the process of nanocomposite preparation, the effect of which was manifested by an increase in the inter-layer GO distance in nanocomposites. It has been observed that the inter-layer spacing of GO and PVA1 is affected by the concentration of the individual components in the nanocomposites, suggesting a possible modification of the PVA1 crystalline structure. Structural analysis revealed that GO layers in composite were oriented in one direction.
Influence of electrode preparation on electrocatalytic activity of water soluble porphyrazine complex to hydrogen
Klusáčková, Monika ; Janda, Pavel ; Tarábková, Hana
The influence of electrode preparation and used electrode substrate on electrocatalytic activity of N, N`,N``,N```tetramethyl-tetra-3,4-pyridinopor-phyrazinocobalt (CoTmt-3,4-ppa) complex deposited on electrode surface for hydrogen reaction has been studied. Electrochemical deposition, spontaneous adsorption, and spin coating have been used to the modification of two different electrode substrates: annealed gold and highly oriented pyrolytic graphite. Prepared electrodes have been characterized using cyclic voltammetry, backscattering VIS spectroscopy and atomic force microscopy. The detailed comparison of surface morphology, surface coverage, surface roughness parameters, and thickness of deposited layers of CoTmt-3,4-ppa mediatoronhydrogen reaction has been investigated.
Electropolymerization of Methylene Blue on Highly Oriented Pyrolytic Graphite and Characterization of Deposited Film
Zlámalová, Magda ; Janda, Pavel ; Nesměrák, K.
This work presents the investigation of methylene blue (MB) polymerization as well as characterization of deposited conductive film on basal plane highly oriented pyrolytic graphite (HOPG) substrate. Poly(methylene blue) modified HOPG electrodes (HOPG/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing monomer methylene blue. Atomic force microscopy (AFM) has been used for the nanomorphological study of immobilized poly(methylene blue) film.
Effect of obstructive sleep apnea on oxidation and transport of fatty acids in skeletal muscle in patients with type 2 diabetes mellitus
Havlíková, Nikola ; Polák, Jan (advisor) ; Gojda, Jan (referee)
Sleep apnea syndrome, or sleep apneic syndrome, is a serious illness that causes a high risk of cardiovascular disease development in patients. This disease is characterized by a breathless breathing disorder and falls into a class of disorder that accompanies sleep disturbances. Sleep apnea syndrome (SAS) affects 5-15% of the population, and 50-80% of patients with type 2 diabetes mellitus (T2DM) or severe obesity. SAS has a causal contribution to the development of disorders in glucose metabolism and T2DM. Diabetes mellitus type 2 is a complex metabolic disorder in which the organism is unable to process glucose as under normal physiological conditions due to a relative insulin deficiency and simultaneous peripheral insulin resistance. Insulin resistance is eventually compensated for by increased insulin secretion, which leads to the development of hyperglycemia after failure of this compensation. T2DM is very often associated with the presence of obesity, arterial hypertension, dyslipidemia and hyperuricemia. The aim of this study is to determine if the presence of SAS in non-diabetic subjects and patients with type 2 diabetes mellitus leads to disorders in the metabolism of fatty acids in the skeletal muscle. The results of the study contribute to the understanding of the molecular mechanisms...
Use of Monovalent Copper for Sensitive Detection of Methyl Derivatives of Xanthine
Navrátil, R. ; Motlova, D. ; Jelen, F. ; Trnková, L.
This work is concerned with the electroanalysis of xanthine (Xan) and its methylated derivatives (1-, 3-, 7-, and 9-mXan) on a pencil graphite electrode in the presence of copper ions. The main idea of using copper consists in the in situ formation of the complex Cu(I)-mXan on the electrode surface and improvement of oxidative signals of the corresponding mXan during the detection. Linear sweep voltammetry (LSV) in connection with adsorption stripping techniques was used for the determination of mXan. To enhance the oxidation signals the elimination voltammetric procedure (EVP) was applied.
Voltammetric determination of 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide by voltammetry at a glassy carbon electrode in microvolumes of dimethyl sulfoxide
Gajdar, J. ; Goněc, T. ; Jampílek, J. ; Brázdová, Marie ; Bábková, Zuzana ; Fojta, Miroslav ; Barek, J. ; Fischer, J.
Voltammetric reduction and oxidation of 1-hydroxy-N-(4-nitrophenyl) naphthalene-2-carboxamide was investigated at glassy carbon electrode in dimethyl sulfoxide. Cyclic voltammetry was used to investigate the mechanism of reduction of nitro group and oxidation of hydroxyl group. The analyte was successfully determined in dimethyl sulfoxide by differential pulse voltammetry and the whole voltammetric procedure was miniaturised. Square wave voltammetry was employed to reduce the interference from dissolved oxygen. Determination in one drop (20 mu L) of 0.1 mol L-1 tetrabutyl-ammonium tetrafluoroborate in dimethyl sulfoxide provided very similar results compared to determination in the bulk solution. Limits of quantification were 5.0 mu mol L-1 for cathodic voltammetry and 5.3 mu mol L-1 for anodic voltammetry.
Voltammetry of 1-Hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide at a Glassy Carbon Electrode
Gajdar, J. ; Goněc, T. ; Jampílek, J. ; Brázdová, Marie ; Bábková, Zuzana ; Fojta, Miroslav ; Barek, J. ; Fischer, J.
This electrochemical study is aimed at an investigation of a reaction mechanism and determination of 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide in media with various amount of an organic solvent (dimethyl sulfoxide or methanol). The studied analyte is a model substance from a group of recently prepared drugs with antibiotic characteriss Mechanism of reducible nitro group and oxidisable hydroxyl group is compared with studies of substructures and structurally similar compounds. Preliminary comparison of different media was carried out to find the best parameters for the determination.
On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside
Castano, A. ; Sokolová, Romana ; Degano, I.
The UV-Vis spectroelectrochemical cell containing an optically transparent platinum net used as the working electrode was tested in two regimes of electrochemical measurement, cyclic voltammetry and chronoamperometry, respectively. A three electrode setup used silver quasi reference electrode and platinum electrode serving as a counter electrode. The calibration of the spectroelectrochemical cell was performed for one-electron oxidation processes as well as for two-electron oxidations. The spectral changes during the oxidation of luteolin-7-O-Glucoside gave the information about the electroactive chromophores in molecule. Resulted spectra were compared with luteolin. The identification of products of oxidation was done by complementary analytical techniques HPLC-DAD and HPLC-ESI-MS/MS.

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