National Repository of Grey Literature 259 records found  beginprevious159 - 168nextend  jump to record: Search took 0.01 seconds. 
Voltammetric Behavior of Folates and Related Substances Using Silver Solid Amalgam Electrode
Bandžuchová, L. ; Šelešovská, R. ; Navrátil, Tomáš ; Chýlková, J.
The possibility of application of silver solid amalgam electrode in voltammetric analysis of compounds with folate structure (folic acid, methotrexate, leucovorin) and substances, which play an important role in its metabolism (riboflavin, hydroxocobalamin) has been investigated. Cyclic voltammetry, DC voltammetry and Elimination voltammetry with linear scan has been used for study of voltammetric behavior of mentioned substances and for elucidation of electrochemical reactions. Differential pulse voltammetry has been applied for development of sensitive methods of determination for investigated electroactive compounds. The proposed methods were successfully applied for real samples analysis. Obtained results have been compared with those achieved using HMDE.
Voltammetric Determination of Herbicide Triasulfuron using Mercury Meniscus Modified Silver Solid Amalgam Electrode
Bandžuchová, L. ; Šelešovská, R. ; Chýlková, J. ; Navrátil, Tomáš
Voltammetric behavior of triasulfuron (TS), which belongs to sulfonylurea herbicide family, was studied using two working electrodes: mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and hanging mercury drop electrode (HMDE) for comparison. It was found that TS provided one reduction peak on both used working electrodes. The highest response was observed in the environment of Britton-Robinson buffer (BR) of pH 3 (m-AgSAE) and 2.5 (HMDE), respectively. Working parameters of differential-pulse voltammetry (DPV) were optimized and this method was applied in analysis of agricultural formula and river water.
Direct Voltammetric Determination of Antioxidant Butylated Hydroxyanisol in Biodiesel
Tomášková, M. ; Chýlková, J. ; Jehlička, V. ; Navrátil, Tomáš ; Šelešovská, R.
Direct voltammetric determination of antioxidant butylated hydroxyanisol (BHA) in isopropanol containing 0.1 mol L-1 H2SO4 using linear sweep voltammetry with gold working electrode was tested. The developed method was purposed for determination of BHA in biodiesel. There were compared the results achieved by nonlinear and linear regression of registered data. This method was applied by analysis of biodiesel samples. These analyses can be performed directly, without necessity of sample treatment or extraction.
Continuous Glucose Monitoring by Real Time Sensor in Interstitial Fluid
Honsová, Š. ; Navrátil, Tomáš
The aim of this contribution is to compare the differences between accuracy claimed by the manufacturer in continuous glucose monitoring using the MiniMed Paradigm REAL-Time system with the results obtained in a patient during physical activity. Electrochemical glucose sensor measures the glucose oxidase reaction products. Measurement accuracy was determined using Clarke Error Grid analysis. It can be concluded that in the normal glucose range (4.4 to 10.0 mmol/ l) was more accurate than the measurements given by the manufacturer, in the opposite case; hyperglycemia is less precise than declared.
DOES ONE MONTH CREATINE SUPPLEMENTATION IMPROVE BLOOD LIPIDS?
Kohlíková, E. ; Petr, M. ; Navrátil, Tomáš ; Heyrovský, Michael ; Přistoupilová, K. ; Přistoupil, T. I.
One month’s administration of creatine (CR) in the dose of 5 g/day to 11 young active sportsmen affected their daily amount of CR excreted into urine, and the levels of cholesterol (CH), of triacylglycerols (TAG), of vitamin B12 and of folates in blood. The probands were divided into 4 groups, according to the amount of CR found in urine, and of folates and vitamin B12 determined in blood. It is possible that added CR might induce individually higher offer of 2C units, released under catalysis of vitamin B12 from HoCySH and serine in enzymatic reaction catalyzed by CBS, and in this way higher offer of cysteine and succinyl-CoA This is the main effect of CR in the group D. Both vitamins influence the ratio between glycine (necessary mainly for CR synthesis, beside other metabolic pathways) and serine. The change of serine into glycine can be realized by THF, under catalysis of serine hydroxymethyltransferase. For the opposite change of glycine into serine the metabolic pathway is catalyzed by folates too, but in more complicated way
Optimization of a Flow Rate for a Hyphenation of Voltammetry with Electrospray Ionization Mass Spectrometry
Jaklová Dytrtová, Jana ; Jakl, M. ; Norková, Renáta ; Navrátil, Tomáš
The hyphenation of an electrochemical cell prior to mass spectrometer with electrospray ionization allows studying of products and/or of intermediates of electrode reactions. The measurement is realized in a flowing system. The flow rate of the sample markedly influences the MS signal intensity of the product. The calculated optimum value for the electrochemical cell with the sweep volume 0.72 μL is in the range from 0.4 to 0.5 mL h -1 . The experimental optimal value is 0.45 mL h -1 . The optimization of the flow rate has to be provided individually for each product, because the intensity also depends on the rate of the electrode reaction and product stability.
Územní aspekty a dlouhodobý monitorovací systém
Česká geologická služba, Praha ; Cudlín, Pavel ; Skořepa, Jaroslav ; Skořepová, Irena ; Krám, Pavel ; Navrátil, Tomáš ; Fottová, Daniela
Monitorovací systém GEOMON koordinovaný ČGS je v současné formě provozován od roku 1994. Ze sítě čtrnácti malých lesních povodí se jednotnou metodikou pořizují vstupní údaje pro výpočet látkových toků ekologicky významných složek. Jedná se o celosvětově uznávaný způsob hodnocení stavu a vývoje přírodního prostředí. Prostředkem k takovému hodnocení je výpočet bilancí, tzn. vstupů a výstupů složek, v přirozených jednotkách biosféry reprezentovaných malým povodím. Vstup do povodí představuje depozice srážkami na volné ploše a pod korunami stromů. jako výstup z povodí je uvažován povrchový odtok. V předložené zprávě je zpracována jedenáctiletá řada dat.
Územní aspekty a dlouhodobý monitorovací systém
Česká geologická služba, Praha ; Skořepa, Jaroslav ; Skořepová, Irena ; Krám, Pavel ; Navrátil, Tomáš ; Cudlín, Pavel ; Fottová, Daniela
Monitorovací systém GEOMON koordinovaný ČGS je v současné formě provozován od roku 1994. Ze sítě čtrnácti malých lesních povodí se jednotnou metodikou pořizují vstupní údaje pro výpočet látkových toků ekologicky významných složek. Jedná se o celosvětově uznávaný způsob hodnocení stavu a vývoje přírodního prostředí. Prostředkem k takovému hodnocení je výpočet bilancí, tzn. vstupů a výstupů složek, v přirozených jednotkách biosféry reprezentovaných malým povodím. Vstup do povodí představuje depozice srážkami na volné ploše a pod korunami stromů. jako výstup z povodí je uvažován povrchový odtok. Soubor dat získaný ze sítě malých povodí GEOMON představuje dvanáctiletou řadu dat a vypočtených výsledků, která je hodnocena jako celek zároveň s předchozími ročními soubory od roku 1994.
Influence of LMWOAs Transport of Cadmium and Copper Ions Across Phospholipid Bilayer Using Calcium Ionophore A23187
Šestáková, Ivana ; Parisová, Martina ; Navrátil, Tomáš ; Jaklová Dytrtová, Jana
The influence of oxalic, citric or malic acid on transport of cadmium and copper ions in dependence on pH has been studied. Artificial phospholipid bilayer containing wide-spectrum ionophore was prepared on polycarbonate support and its formation and stability was followed with electrochemical impedance spectroscopy. The species, transported across phospholipid bilayer were determined with voltammetry. The substantial influence of complexes formed with metal ions and LMWOAs on their transport has been confirmed.

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1 Navrátil, T.
4 Navrátil, Tadeáš
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