Ústav fyzikální chemie J. Heyrovského

Nejnovější přírůstky:
2018-03-09
13:19
Long-Term Sustainability of Research Infrastructures
Hrušák, Jan ; Harrison, A. ; Lenoir, L.
The second volume of the ESFRI Scripta series is dedicated to\nthe outcomes of the ad hoc Working (WG) Group on Long-Term\nSustainability (LTS) of Research Infrastructures.\nThe LTS WG was created by ESFRI in 2016 to comprehensively respond\nto the Conclusions of the Competitiveness Council of the European\nUnion of 27th May 2016 that „underlines the importance of ensuring\nLong-Term Sustainability of Research Infrastructures and invites the\nCommission to prepare together with ESFRI and relevant stakeholders a\ntargeted action plan“.\nESFRI has previously developed its concept of lifecycle of the Research\nInfrastructures in the framework of the Roadmap evaluation exercise,\nand at all stages of the lifecycle different aspects of sustainability were\nidentified. The LTS WG has analysed the Long-Term Sustainability\nof Research Infrastructures from a broad perspective taking the\nESFRI viewpoint well beyond the mere economical analysis. Scientific\nexcellence is the condition sine qua non for sustainability throughout\nthe entire RI lifecycle, and its persistence is crucial in the long-term\noperational phase. Excellence in science and outstanding quality services\nto the users are imperative for the successful performance of each\nResearch Infrastructure, and they are addressed in the monitoring and\nreviewing processes by ESFRI.

Úplný záznam
2018-03-07
15:28
Material properties of lithium fluoride for predicting XUV laser ablation rate and threshold fluence
Blejchař, T. ; Nevrlý, V. ; Vašinek, M. ; Dostál, Michal ; Pečínka, L. ; Dlabka, J. ; Stachoň, M. ; Juha, Libor ; Bitala, P. ; Zelinger, Zdeněk ; Pira, P. ; Wild, J.
This paper deals with prediction of extreme ultraviolet (XUV) laser ablation of lithium fluoride at nanosecond timescales. Material properties of lithium fluoride were determined based on bibliographic survey. These data are necessary for theoretical estimation of surface removal rate in relevance to XUV laser desorption/ablation process. Parameters of XUV radiation pulses generated by the Prague capillary-discharge laser (CDL) desktop system were assumed in this context. Prediction of ablation curve and threshold laser fluence for lithium fluoride was performed employing XUV-ABLATOR code. Quasi-random sampling approach was used for evaluating its predictive capabilities in the means of variance and stability of model outputs in expected range of uncertainties. These results were compared to experimental data observed previously.

Úplný záznam
2018-03-07
15:28
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.
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.

Úplný záznam
2018-03-07
15:28
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
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.

Úplný záznam
2018-03-07
15:28
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
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.

Úplný záznam
2017-10-30
13:46
Miniaturized Boron Doped Diamond Film Electrode for Neuroblastoma Biomarkers Determination
Hrdlička, Vojtěch ; Barek, J. ; Navrátil, Tomáš ; Taylor, Andrew
Cathodically pretreated miniaturized boron doped diamond film\nelectrode was successfully tested for the purposes of in-situ determination\nof neuroblastoma biomarkers after hollow-fibre based\nmicroextraction. Electrode was tested using K3[Fe(CN)6] and vanillylmandelic\nacid as model substances . Limits of detection and\ndetermination are 2.2 and 6.6 mu mol L-1, respectively. Linear range was\n2.2-100 mu mol L-1, repeatability 1.34% (n = 10).

Úplný záznam
2017-10-30
13:46
Voltammetric Determination of Tumor Biomarkers using Flow Injection Analysis with Amperometric Detection
Makrlíková, Anna ; Matysik, F.-M. ; Barek, J. ; Vyskočil, V.
Three tumor biomarkers (homovanillic acid, vanillylmandelic acid,\nand 5-hydroxyindole-3-acetic acid) have been determined by flow\ninjection analysis with amperometric detection at screen-printed\ncarbon electrodes in optimum medium of Britton-Robinson buffer\n(0.04 mol l-1, pH = 2.0). Dependences of the peaks current on the\nconcentration of biomarkers were linear in the tested concentration\nregion from 0.05 to 100 mu mol l-1, with the limits of detection of\n0.065 mu mol l-1 for homovanillic acid, 0.053 mu mol l-1 for vanillylmandelic\nacid, and 0.033 mu mol l-1 for 5-hydroxyindole-3-acetic acid (calculated\nfrom heights), and 0.024 mu mol 1-1 for homovanillic acid,\n0.020 mu mol l-1 forvanillylmandelic acid, and 0.012 mu mol l-1 for 5-hydroxyindole-3-acetic acid (calculated from areas), respectively.

Úplný záznam
2017-10-30
13:46
Pilot Experiments With a Micro-Volume Voltammetric Cell for the Determination of Electrochemically Reducible Organic Compounds
Skalová, Štěpánka ; Barek, J. ; Rodrigues, J. A. ; Goncalves, L.M. ; Navrátil, Tomáš ; Vyskočil, V.
A new micro-volume voltammetric cell for analysis of small volumes\nof electrochemically reducible organic compounds was developed\nand tested. The sample (20-100 mu L) is placed in a narrow glass tube\nwith an agar membrane at the bottom and the working electrode is\nimmersed into the sample. The agar membrane, as anion permeable\nlayer, electrically connects the workin g e lectrode immersed in the\nanalysed sample in the glass tube with a large-volume compartment\n(20 mL) filled with Britton-Robinson buffer, where conventional nonminiaturized\nreference and auxiliary electrodes are placed. The system\nwas tested using a polished silver solid amalgam electrode\n(p-AgSAE) as a working electrode. Sodium anthraquinone-2-sulfonate\nwas used as a model compound because it is intended to use this\nsystem to monitor electrochemically reducible organic compounds.

Úplný záznam
2017-06-12
14:36
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Hromadová, Magdaléna ; Kocábová, Jana ; Kolivoška, Viliam ; Pospíšil, Lubomír
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.

Úplný záznam
2017-06-12
14:36
Graphite Electrode Modified by Poly(Methylene Blue) and its Electrocatalytic Activity towards Hydrogen Sulfide Oxidation
Zlámalová, Magda ; Janda, Pavel ; Nesměrák, K.
This research is focused on the electrochemical synthesis and characterization of\npoly(methylene blue) (pMB). Two different carbon-based electrode substrates, basal plane\nhighly oriented pyrolytic graphite (HOPG) and pencil graphite electrode (PGE), have been\nmodified by conductive film of pMB. Electrochemical properties and nanomorphological\nchanges have been investigated by cyclic voltammetry and atomic force microscopy.\nImproved electroactivity of the modified electrodes (PGE/pMB and HOPG/pMB) towards\nsulfhydryl group has been observed and examined modified electrodes were researched for\ntheir possible application in electrochemical sensor for hydrogen sulfide in aqueous solutions.

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