Number of found documents: 404
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Determination of 5-hydroxyindole-3-acetic acid using Flow Injection Analysis with Electrochemical Detection
Makrlíková, Anna; Matysik, F.-M.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2017 - English
Tumour biomarker, 5-hydroxyindole-3-acetic acid, has been determined at screen-printed carbon electrodes using flow injection analysis with amperometric detection. Britton-Robinson buffer (0.04 mol-l-1 , pH 2.0) was used as an optimum carrier solution.\nDependence of the peak current on the analyte concentration was linear in the whole tested\nconcentration range (from 0.5 to 100 mikromol-l-1) with limits of detection 0.033 mikromol-l-1 \n(calculated from peak heighst) and 0.012 mikromol-l-1 (calculated from peak areas). Keywords: Amperometric detection; Flow injection analysis; 5-Hydroxyindole-3-acetic acid Available on request at various institutes of the ASCR
Determination of 5-hydroxyindole-3-acetic acid using Flow Injection Analysis with Electrochemical Detection

Tumour biomarker, 5-hydroxyindole-3-acetic acid, has been determined at screen-printed carbon electrodes using flow injection analysis with amperometric detection. Britton-Robinson buffer (0.04 ...

Makrlíková, Anna; Matysik, F.-M.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2017

Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Hromadová, Magdaléna; Kocábová, Jana; Kolivoška, Viliam; Pospíšil, Lubomír
2017 - English
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results show that the oxide growth kinetics depends on pH of the electrolyte\nsolution and the total amount of irreversibly formed oxide under the potentiodynamic\nconditions decreases with decreasing buffer pH in accord with thermodynamic considerations.\nCathodic current corresponding to hydrogen evolution reaction diminishes in the presence of\nanodically modified electrode compared to bare zirconium. Keywords: zirconium; oxide film; hydrogen evolution Available on request at various institutes of the ASCR
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode

Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results ...

Hromadová, Magdaléna; Kocábová, Jana; Kolivoška, Viliam; Pospíšil, Lubomír
Ústav fyzikální chemie J. Heyrovského, 2017

High resolution infrared spectroscopy as diagnostic tool for combustion and plasma chemistry
Zelinger, Zdeněk; Nevrlý, Václav; Grigorová, Eva; Bitala, P.; Dostál, Michal; Suchánek, Jan; Kubát, Pavel; Engst, Pavel; Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk
2017 - English
Monitoring of transient species within combustion experiments (laminar flames, shock-tubes, flow reactors, etc.) is still relatively challenging task especially if application of non-invasive, i.e. optical detection methods is required. High resolution infrared spectroscopy is based on observation of the fine rotation structure that accompanies vibration transitions and thus provides direct information essential to characterization of both molecular structure and reaction dynamics. Thanks to its outstanding advantage enabling unambiguous assignment of specific molecular system according to its spectral feature, it can serve as a helpful tool for exploring complex reaction mechanisms as well as chemical reactivity of individual species present in laboratory flames or plasmas.\nPrevious studies gaining new insights into combustion and plasma chemistry as well as our recent advances targeted towards application of high resolution infrared spectroscopy for species concentration measurement in laminar flames are summarized here below. Keywords: spectroscopy; plasma chemistry; infrared spectra Available at various institutes of the ASCR
High resolution infrared spectroscopy as diagnostic tool for combustion and plasma chemistry

Monitoring of transient species within combustion experiments (laminar flames, shock-tubes, flow reactors, etc.) is still relatively challenging task especially if application of non-invasive, i.e. ...

Zelinger, Zdeněk; Nevrlý, Václav; Grigorová, Eva; Bitala, P.; Dostál, Michal; Suchánek, Jan; Kubát, Pavel; Engst, Pavel; Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk
Ústav fyzikální chemie J. Heyrovského, 2017

Wavelength modulation spectroscopy for multicomponent ana-lytics of biomass burning tracers
Dostál, Michal; Válek, V.; Suchánek, Jan; Kristlová, E.; Roupcová, P.; Zelinger, Zdeněk; Nevrlý, Václav; Bitala, P.; Vašinek, M.; Kubát, Pavel; Ferus, Martin; Civiš, Svatopluk
2017 - English
The potential of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for monitoring of several species produced by biomass burning is in focus of this work. The infrared spectra of selected molecules (HCOOH, C2H2, CH3CN, N2O, CH3OH, CH3COCH3) are measured in laboratory conditions and the selectivity and of this method is demonstrated. Keywords: spectroscopy; biomass burning tracers; TDLAS system Available at various institutes of the ASCR
Wavelength modulation spectroscopy for multicomponent ana-lytics of biomass burning tracers

The potential of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for monitoring of several species produced by biomass burning is in focus of this work. The infrared spectra of selected molecules ...

Dostál, Michal; Válek, V.; Suchánek, Jan; Kristlová, E.; Roupcová, P.; Zelinger, Zdeněk; Nevrlý, Václav; Bitala, P.; Vašinek, M.; Kubát, Pavel; Ferus, Martin; Civiš, Svatopluk
Ústav fyzikální chemie J. Heyrovského, 2017

Hydroxyl radical measurement in atmospheric pressure dimethyl ether-air laminar premixed flat flame using tunable diode laser absorption spectroscopy
Nevrlý, V.; Dostál, Michal; Bitala, P.; Zelinger, Zdeněk; Suchánek, Jan; Válek, V.; Klečka, V.; Kubát, Pavel; Engst, Pavel; Vašinek, M.; Wild, J.
2017 - English
Spectroscopic detection of hydroxyl (OH) radical and determination of its concentration in flames have an elusive history and considerable influence on combustion research. Electronic transitions in ultraviolet spectral region were extensively studied in this context and until recent time chemiluminescence or laser induced fluorescence of excited hydroxyl (OH*) radical is broadly used for absolute concentration and temperature measurement in flames.\nHowever, number densities of molecular species and population of relevant quantum levels in ground electronic state can be directly estimated from intensities of absorption lines observed by probing rovibrational transitions in infrared spectral region. Application of near-infrared tunable diode laser absorption spectroscopy (NIR-TDLAS) for the given purpose was demonstrated in an earlier work of Aizawa et al. [1]. Following his pioneering studies summarized in [2], we further explored feasibility of NIR-TDLAS (especially 2f-WMS technique) for monitoring minor species within combustion experiments particularly when dealing with dimethyl ether (DME) flames. Here we report our first results of NIR-TDLAS measurements focused on hydroxyl radical detection in laminar premixed flame burning DME-air mixture under fuel-lean conditions. Keywords: spectroscopy; tunable diode laser absorption spectroscopy; hydroxyl Available on request at various institutes of the ASCR
Hydroxyl radical measurement in atmospheric pressure dimethyl ether-air laminar premixed flat flame using tunable diode laser absorption spectroscopy

Spectroscopic detection of hydroxyl (OH) radical and determination of its concentration in flames have an elusive history and considerable influence on combustion research. Electronic transitions in ...

Nevrlý, V.; Dostál, Michal; Bitala, P.; Zelinger, Zdeněk; Suchánek, Jan; Válek, V.; Klečka, V.; Kubát, Pavel; Engst, Pavel; Vašinek, M.; Wild, J.
Ústav fyzikální chemie J. Heyrovského, 2017

Mystery of Ageing of „Zero-Valent Iron“ (ZVI)
Wouafo, M. T.; Donkeng Dazie, Joel; Tchatchueng, J. B.; Noubactep, Ch.; Ludvík, Jiří
2017 - English
So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and oxygen cannot be considered as pure Fe0 but as a mixture of its corrosion products.\nThe remediation process occurs on the surface of these iron particles, hence, the degree of\n„corrosion“ is crucial for the process itself. Therefore, investigation of „aging“ of ZVI is an\nimportant prerequisite for deeper understanding of its activity.\nIn this work, the first results of the systematic study of aging of iron metal powder are\npresented. The investigation was performed in batch conditions in aqueous buffered solutions\npH 4, 4.7, 5.5 and in the presence of air oxygen. Increasing and then decreasing concentration\nof the Fe2+ ion in the solution appeared to be the important marker of aging process.\nIn the second part of the work, removal of Zn2+ ions using ZVI was investigated.\nElectrochemical techniques, namely polarography and its differential pulse form (DPP) were\nused for permanent monitoring of the presence of Fe2+ and Zn2+ ions in the studied solution.\nChanging concentrations of both ions revealed that at pH 5.5 the optimum aging time of ZVI\nfor removal of Zn2+ from aqueous solution is 6 hours. Keywords: zero-valent iron; aging effect; zinc ion removal Available on request at various institutes of the ASCR
Mystery of Ageing of „Zero-Valent Iron“ (ZVI)

So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and ...

Wouafo, M. T.; Donkeng Dazie, Joel; Tchatchueng, J. B.; Noubactep, Ch.; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2017

Redox Properties of Quasi Dimer of 1,3-diphenylisobenzofuran for Singlet Fission
Šimková, Ludmila; Ludvík, Jiří
2017 - English
Molecules on the base of 1,3-diphenylisobenzofuran attract an interest because of their\npossible efficiency for singlet fission This study is focused on electrochemical behaviour of\nthe „quasi dimer“ of 1,3-diphenylisobenzofuran. For characterization of reduction mechanism\nin situ UV-vis and EPR spectroscopy were used. The monomer 1,3-diphenylisobenzofuran\nand its CH2 dimer were added to this study for comparison. The redox properties of both\ncompared molecules are similar. The location and the nature of the covalent bridging unit in\nCH2dimer have small effect onthe redox potentials. But the pi-conjugation in the molecule of\nquasi dimer causes approximately 0.2 V easier oxidization and reduction. Keywords: 1,3-diphenylisobenzofuran; dimer; Singlet fission Available on request at various institutes of the ASCR
Redox Properties of Quasi Dimer of 1,3-diphenylisobenzofuran for Singlet Fission

Molecules on the base of 1,3-diphenylisobenzofuran attract an interest because of their\npossible efficiency for singlet fission This study is focused on electrochemical behaviour of\nthe „quasi ...

Šimková, Ludmila; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2017

Labile Lead Phytochelatin Complexes Could Enhance Transport of Lead Ions across Biological Membrane
Šestáková, Ivana; Navrátil, Tomáš
2017 - English
In connection with studies of hazardous metals transport across model phospholipid\nmembranes, behavior of complexes of lead with phytochelatin PC2 has been examined. Using\nstripping chronopotentiometry with different values of reducing current, the release of free\nlead ions confirms labile behavior. Similar conclusion resulted from voltammetry on silica gel\nmodified carbon paste electrode. Keywords: phytochelatin; lead; voltammetry Available on request at various institutes of the ASCR
Labile Lead Phytochelatin Complexes Could Enhance Transport of Lead Ions across Biological Membrane

In connection with studies of hazardous metals transport across model phospholipid\nmembranes, behavior of complexes of lead with phytochelatin PC2 has been examined. Using\nstripping ...

Šestáková, Ivana; Navrátil, Tomáš
Ústav fyzikální chemie J. Heyrovského, 2017

Redakčně upravená závěrečná zpráva projektu DF11P01OVV012: Nové materiály a technologie pro konzervaci materiálů památkových objektů a preventivní památkovou péči
Rathouský, Jiří; Slížková, Zuzana; Kotlík, P.
2016 - Czech
Projekt byl zaměřen na vývoj nových materiálů a technologií pro komplexní řešení problematiky uchování hodnot hmotného kulturního dědictví v ČR zejména s ohledem na čištění historických materiálů s využitím mikroemulzí a micelárních roztoků, konsolidaci objektů pomocí nanodisperzí hydroxidu vápenatého a modifikovaných ethylsilikátových gelů a preventivní ochranu materiálů proti působení vnějšího prostředí a biokorozi, včetně zachování jejich původního vzhledu. This project was focused on development of new materials and technologies for complex solution of problems with preservation of a cultural heritage in the Czech Republic. Main interests were conservation activities as cleaning of historical materials using microemulsions and micellar solutions, consolidation by calcium hydroxide and modified ethylsilicate gels and protection of materials against environment effects and biocorrosion, including protection of the original appearance of the historic materials. Keywords: consolidation; cleaning of historical materials; protection Available at various institutes of the ASCR
Redakčně upravená závěrečná zpráva projektu DF11P01OVV012: Nové materiály a technologie pro konzervaci materiálů památkových objektů a preventivní památkovou péči

Projekt byl zaměřen na vývoj nových materiálů a technologií pro komplexní řešení problematiky uchování hodnot hmotného kulturního dědictví v ČR zejména s ohledem na čištění historických materiálů s ...

Rathouský, Jiří; Slížková, Zuzana; Kotlík, P.
Ústav fyzikální chemie J. Heyrovského, 2016

Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů
Švecová, H.; Sokolová, Romana; Součková, J.; Skopalová, J.; Barták, P.
2016 - Czech
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. In this article we described glassy carbon electrode modified with Asolectin (mixture of phosholipids). Properties of phospholipid layer, such as its thickness or solidity, were investigated using atomic force microscopy (AFM). The modified electrode was applied for square wave voltammetry (SWV) measurements to study interactions of pesticide paraquat with phospholipid layer and to detect paraquat selectively in real samples of river water. Keywords: paraquat; electrochemistry; phospholipids Available at various institutes of the ASCR
Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů

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 ...

Švecová, H.; Sokolová, Romana; Součková, J.; Skopalová, J.; Barták, P.
Ústav fyzikální chemie J. Heyrovského, 2016

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