Počet nalezených dokumentů: 10
Publikováno od do

Construction and application of the amperometric uric acid biosensors based on the covalent immobilization of uricase by different strategies
Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan
2021 - anglický
In this work, a promising combination of a biosensor based on the\nenzymatic mini-reactor with the detection principle of four-electron\nreduction of the consumed oxygen at highly negative potential has\nbeen developed for uric acid determination using flow injection\nanalysis. The construction of the biosensor provides a spatial\nsegregation of the biorecognition (uricase-based mini-reactor) and\ndetection (tubular detector of silver solid amalgam (TD-p-AgSA))\nparts. To find out the most appropriate enzyme immobilization\nprotocol, three different strategies of the covalent attachment for\nuricase from Bacillus fastidiosus have been compared. It was found\nthat the biosensor with the mini-reactor based on the covalent\nattachment of uricase via glutaraldehyde to -NH2 functionalized\nmesoporous silica powder MCM-41 showed extremely high stability\n(>1 year) and reusability (at least 600 measurements) The biosensor's\npractical applicability was confirmed by successful determination\nof uric acid in human urine. Klíčová slova: amalgam electrode; amperometric biosensor; uric acid Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Construction and application of the amperometric uric acid biosensors based on the covalent immobilization of uricase by different strategies

In this work, a promising combination of a biosensor based on the\nenzymatic mini-reactor with the detection principle of four-electron\nreduction of the consumed oxygen at highly negative potential ...

Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan
Ústav fyzikální chemie J. Heyrovského, 2021

IMPOSING BIAXIAL STRAIN ON 2D LAYERED MATERIALS BY LIQUID-INDUCED SWELLING OF SUPPORTING POLYMER
Sampathkumar, Krishna; Pekárek, J.; Frank, Otakar
2021 - anglický
2D layered materials promise to revolutionize the field of electronics, photonics, optoelectronics, energy storage, and sensing, etc. 2D materials have exceptional mechanical properties, with critical elongation >10%. Employing the strain to manipulate the electronic structure of these 2D materials could lead to further improvement of their implementation in many aspects. The ease of manipulation of their electronic structure can be one of the critical factors for their utilization in photonic devices. Apart from the strain, which decreases (increases) the bandgap energy at the rate of similar to 100 meV under 1% of biaxial tension (compression), also the layer number causes bandgap energy change of, e.g., 0.5 eV between bulk (1.3 eV) and monolayer MoS2 (1.8 eV). In our work, we focus on using the swelling behavior of PMMA/SU8 polymer in methanol to impose the strain on 2D layered materials. In the first trials, we have shown that it is possible to reach a strain gradient from 0 to similar to 0.5% of biaxial strain via simple swelling of polymer substrates, both for graphene [1] and transition metal di-chalcogenides (TMDC) like MoS2. Raman spectroscopy was used to probe the lattice strain in the materials through measuring changes of vibrational frequencies, and photoluminescence was used to probe the strain-induced bandgap character and energy in TMDC at room temperature. The surface corrugation of the 2D material after the soaking was recorded with the help of atomic force microscope (AFM). Klíčová slova: raman-spectroscopy; graphene; monolayer; bubbles; 2D material; graphene; tmdc; strain engineering; biaxial strain Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
IMPOSING BIAXIAL STRAIN ON 2D LAYERED MATERIALS BY LIQUID-INDUCED SWELLING OF SUPPORTING POLYMER

2D layered materials promise to revolutionize the field of electronics, photonics, optoelectronics, energy storage, and sensing, etc. 2D materials have exceptional mechanical properties, with critical ...

Sampathkumar, Krishna; Pekárek, J.; Frank, Otakar
Ústav fyzikální chemie J. Heyrovského, 2021

ELECTROCHEMICAL STUDY OF CuSCN INORGANIC HOLE-TRANSPORT MATERIAL FOR SOLAR CELLS PREPARED BY ELECTRODEPOSITION FROM AQUEOUS SOLUTION
Vlčková Živcová, Zuzana; Mansfeldová, Věra; Bouša, Milan; Kavan, Ladislav
2021 - anglický
A comparative study is reported for electrodeposited copper(I) thiocyanate layers (ca. 500 nm) on two types of conductive/semiconductive substrates: i) carbon (boron-doped diamond_BDD, glass-like carbon_GC), and ii) carbon-free F-doped SnO2 conducting glass (FTO). SEM and Raman evidence that electrodeposition from aqueous solution results in homogenous CuSCN layers with dominant thiocyanate ion bounded to copper through its S-end (Cu−SCN bonding), as in spin-coated CuSCN layers. Electrochemical impedance spectroscopy (EIS) confirms the p-type semiconductivity of layers with a flatband potential from 0.1 to 0.18 V vs. Ag/AgCl depending on the substrate type, and the acceptor concentration (NA) of 5 x 1020cm-3 in all cases. The flatband potentials determined from Mott-Schottky plots (EIS) are in good agreement with the Kelvin probe measurements. The blocking quality of CuSCN layers was tested using Ru(NH3)63+/2+ redox probe. CuSCN deposited on BDD substrate exhibits better blocking properties compared to CuSCN deposited on FTO. Klíčová slova: electrodeposition; CuSCN; hole transport material Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
ELECTROCHEMICAL STUDY OF CuSCN INORGANIC HOLE-TRANSPORT MATERIAL FOR SOLAR CELLS PREPARED BY ELECTRODEPOSITION FROM AQUEOUS SOLUTION

A comparative study is reported for electrodeposited copper(I) thiocyanate layers (ca. 500 nm) on two types of conductive/semiconductive substrates: i) carbon (boron-doped diamond_BDD, glass-like ...

Vlčková Živcová, Zuzana; Mansfeldová, Věra; Bouša, Milan; Kavan, Ladislav
Ústav fyzikální chemie J. Heyrovského, 2021

A comparative study of covalent glucose oxidase and laccase immobilization techniques at powdered supports for biosensors fabrication
Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan; Nesměrák, K.
2020 - anglický
In order to develop the optimal strategy and to deepen the knowledge in the field of enzyme immobilization, three different techniques of covalent binding for two enzymes (glucose oxidase and laccase) at powdered surfaces were compared. Immobilization protocol was optimized by changing supports (two mesoporous silica powders (SBA−15, MCM−41) and a cellulose powder), the functionalized\ngroups introduced at support surfaces (−NH and −COOH), and the methods of activation (glutaraldehyde and carbodiimide). Amino and carboxyl functionalized mesoporous silica and cellulose powders\nwere prepared by silanization using (3-aminopropyl)triethoxysilane and carboxyethylsilanetriol, respectively. It was found that coupling of both enzymes by their –NH groups through glutaraldehyde to -NH functionalized supports, in particular SBA15−NH and cellulose−NH for glucose oxidase, MCM41−NH for laccase, showed the highest activity and the best stability. Klíčová slova: biosensors; covalent immobilization; enzymatic reactor Dokument je dostupný na externích webových stránkách.
A comparative study of covalent glucose oxidase and laccase immobilization techniques at powdered supports for biosensors fabrication

In order to develop the optimal strategy and to deepen the knowledge in the field of enzyme immobilization, three different techniques of covalent binding for two enzymes (glucose oxidase and laccase) ...

Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan; Nesměrák, K.
Ústav fyzikální chemie J. Heyrovského, 2020

Photocatalytic concrete screeds with self-cleaning and antimicrobial function
Bíbová, Hana; Šubrt, Jan; Pližingrová, Eva; Jakubičková, M.; Sázavská, T.; Dohnálek, P.; Hykrdová, Lenka; Jirkovský, Jaromír
2020 - anglický
Photocatalytic concrete screeds with self-cleaning and antimicrobial function have been developed and tested. These building materials contain sand grains with deposited composite TiO2/SiO2 layers. Two types of the screeds, grey and white, were prepared and their photoactivity and material characteristics were compared. Commercial TiO2 photocatalysts from several manufacturers were employed. Effects of different parameters, such as temperature of the coated sand calcination, humidity, and surface abrasion, were followed. Mechanical properties of the screeds were analyzed by SEM/XRD microscopy. Photocatalytic activity was tested by means of NOx oxidation (ISO norm 22197-1/2007). Antibacterial activity was evaluated by modified ISO norm 27447/2009 with Bacillus subtilis as a model organism. Klíčová slova: Antimicrobial activity; NOx; Photodegradation; Self-cleaning screed; sem Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Photocatalytic concrete screeds with self-cleaning and antimicrobial function

Photocatalytic concrete screeds with self-cleaning and antimicrobial function have been developed and tested. These building materials contain sand grains with deposited composite TiO2/SiO2 layers. ...

Bíbová, Hana; Šubrt, Jan; Pližingrová, Eva; Jakubičková, M.; Sázavská, T.; Dohnálek, P.; Hykrdová, Lenka; Jirkovský, Jaromír
Ústav fyzikální chemie J. Heyrovského, 2020

On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside
Castano, A.; Sokolová, Romana; Degano, I.
2019 - anglický
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. Klíčová slova: spectroelectrochemistry; oxidation; luteolin; antioxidants Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside

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 ...

Castano, A.; Sokolová, Romana; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2019

Continuous monitoring of anthraquinone-based anticancer drugs by amperometric technique
Skalová, Štěpánka; Fischer, J.; Barek, J.; Navrátil, Tomáš; Krejčí, J.; Kučerová, R.; Vyskočil, V.
2019 - anglický
This contribution is focused on the development of electroanalytical methods for the monitoring of anthraquinone-based anticancer drugs in physiological solution by combination of liquid-flow system and dialysis catheter, possibly inserted into blood circulation of patients. For this purpose, amperometric detection with dual glassy carbon electrode was developed and derivate of these drugs, anthraquinone-2-sulphonate, was used as a model compound. Two different flow rates of carrier solution (physiological solution) were tested (specifically, 1 and 5 mu L min(-1)) and the dependence of peak currents of anthraquinone-2-sulphonate on its concentration was verified Klíčová slova: amperometric detection; anthracyclines; anthraquinone-2-sulphonate Dokument je dostupný na externích webových stránkách.
Continuous monitoring of anthraquinone-based anticancer drugs by amperometric technique

This contribution is focused on the development of electroanalytical methods for the monitoring of anthraquinone-based anticancer drugs in physiological solution by combination of liquid-flow system ...

Skalová, Štěpánka; Fischer, J.; Barek, J.; Navrátil, Tomáš; Krejčí, J.; Kučerová, R.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2019

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 - anglický
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. Klíčová slova: spectroscopy; plasma chemistry; infrared spectra Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
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 - anglický
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. Klíčová slova: spectroscopy; biomass burning tracers; TDLAS system Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
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 - anglický
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. Klíčová slova: spectroscopy; tunable diode laser absorption spectroscopy; hydroxyl Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
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

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