Počet nalezených dokumentů: 6904
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A New Hollow Fiber-Based Liquid-Phase Microextraction Method for the Determination of Antihypertensive Drug Lercanidipine in Biological Samples
Labzova, O.; Hrdlička, Vojtěch; Navrátil, Tomáš; Šelešovská, R.
2024 - anglický
A new hollow fiber-based liquid-phase microextraction (HF-LPME) method for the determination of antihypertensive drug lercandipine (LCN) in biological samples was developed. HF-LPME was\ncombined with optimized square wave voltammetry (SWV) on a cathodically pre-treated screenprinted boron-doped diamond electrode (SP-BDDE). Optimum HF-LPME conditions were:\nsupported liquid membrane (SLM) dodecane, 0.02 mol L-1 Britton-Robinson buffer (BRB, pH = 3) acceptor phase, BRB (pH = 7) donor phase, and time of extraction 30 min. Limits of quantification (LOQ) and detection (LOD) were 3.3 and 1.1 nmol L-1, respectively. The applicability of the developed method was verified on human urine, blood serum, and blood plasma with 20 and 100 nmol L-1 LCN addition. Klíčová slova: Lercanidipine hydrochloride; Hollow fiber liquid-phase microextraction; Screenprinted boron-doped diamond electrode Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
A New Hollow Fiber-Based Liquid-Phase Microextraction Method for the Determination of Antihypertensive Drug Lercanidipine in Biological Samples

A new hollow fiber-based liquid-phase microextraction (HF-LPME) method for the determination of antihypertensive drug lercandipine (LCN) in biological samples was developed. HF-LPME was\ncombined with ...

Labzova, O.; Hrdlička, Vojtěch; Navrátil, Tomáš; Šelešovská, R.
Ústav fyzikální chemie J. Heyrovského, 2024

Surfactant-free silver nanofluids as liquid systems with neuromorphic potential
Nikitin, D.; Biliak, K.; Lemke, J.; Protsak, M.; Pleskunov, P.; Tosca, M.; Ali-Ogly, S.; Červenková, V.; Adejube, B.; Bajtošová, L.; Černochová, Zulfiya; Prokeš, J.; Křivka, I.; Biederman, H.; Faupel, F.; Vahl, A.; Choukourov, A.
2024 - anglický
Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based on the resistive switching effect, which involves changing the device’s conductivity in response to an external electric field. For instance, percolating nanoparticle (NP) networks produced by gas aggregation cluster sources (GAS) show collective spiking behavior in conductivity reminiscent of brain-like dynamics. Nevertheless, the problem of dynamic spatial reconfiguration in solid-state neuromorphic systems remains unsolved. Herein, novel nanofluids with resistive switching properties are proposed as neuromorphic media. They are produced by depositing silver NPs from GAS into vacuum-compatible liquids (paraffin, silicon oil, and PEG) without the use of surfactants or other chemicals. When the electric field is applied between two electrodes, the migration of NPs toward biased electrode is detected in all liquids. The electrophoretic nature of the NP movement was proved by means of ζ-potential measurements. Such movement led to the self-assembly of NPs in conductive paths connecting the electrodes and, as a result, to resistive switching. The electrical response was strongly dependent on the dielectric constant of the base liquid. The Ag-PEG nanofluid demonstrated the best switching performance reproducible during several tens of current-voltage cycles. The growth of flexible and reconfigurable conductive filaments in nanofluids makes them suitable media for potential realization of 3D neural networks. Klíčová slova: nanofluid; gas aggregation cluster source; ζ-potential, electrophoresis Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Surfactant-free silver nanofluids as liquid systems with neuromorphic potential

Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based ...

Nikitin, D.; Biliak, K.; Lemke, J.; Protsak, M.; Pleskunov, P.; Tosca, M.; Ali-Ogly, S.; Červenková, V.; Adejube, B.; Bajtošová, L.; Černochová, Zulfiya; Prokeš, J.; Křivka, I.; Biederman, H.; Faupel, F.; Vahl, A.; Choukourov, A.
Ústav makromolekulární chemie, 2024

Electrochemical Properties of Pretomanid. New drug for Tuberculosis Treatment
Deri, M.; Vespi, M.; Giannarelli, S.; Hromadová, Magdaléna
2024 - anglický
The electrochemical behavior of Pretomanid (PA 824) has been investigated in acetonitrile by cyclic voltammetry at different scan rates and compared to dimetridazole reduction in order to elucidate its redox mechanism. Both compounds show similar reduction behavior in the aprotic solvent that involves one electron transfer to the nitro group. The reduction of Pretomanid is more difficult and the stability of its nitro anion radical is much lower compared to the dimetridazole molecule. Klíčová slova: pretomanid; dimetridazole; cyclic voltammetry; reduction mechanism Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Properties of Pretomanid. New drug for Tuberculosis Treatment

The electrochemical behavior of Pretomanid (PA 824) has been investigated in acetonitrile by cyclic voltammetry at different scan rates and compared to dimetridazole reduction in order to elucidate ...

Deri, M.; Vespi, M.; Giannarelli, S.; Hromadová, Magdaléna
Ústav fyzikální chemie J. Heyrovského, 2024

Redox Properties of Pyrene-Cyclohexene Conjugates – Electrochemical Study
Koláčná, Lucie; Čubiňák, M.; Tobrman, T.; Ludvík, Jiří
2024 - anglický
The series of 16 compounds for "organic electronics" comprising the double-bond cyclohexene core extended by pyrene and/or other aromatics were electrochemically characterized by rotating disk voltammetry in N,N-dimethylformamide. Due to multiple substitutions, the resulting potential gap represents the sum of all substituent effects. Different combinations of substituents can be used to achieve the desired properties of cyclohexene-pyrene derivatives. The electrochemical data presented in this contribution facilitate further tuning of properties of these molecules and systems to achieve features required in material chemistry just by means of chemical modification. Klíčová slova: pyrene; cyclohexene; conjugation Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Redox Properties of Pyrene-Cyclohexene Conjugates – Electrochemical Study

The series of 16 compounds for "organic electronics" comprising the double-bond cyclohexene core extended by pyrene and/or other aromatics were electrochemically characterized by rotating disk ...

Koláčná, Lucie; Čubiňák, M.; Tobrman, T.; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2024

Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural
Donkeng Dazie, Joel; Koláčná, Lucie; Urban, Jiří; Lamač, Martin; Ludvík, Jiří
2024 - anglický
Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into furfuryl amines which are important precursors namely for pharmaceutical synthesis. First, FF and HMF underwent condensation reactions with various amines which were electrochemically monitored to optimize the process. The resulting Schiff bases were identified by NMR and subsequently electrochemically reduced in basic media. The vicinal diamine (aminopinacol) was the main product besides the expected furfuryl amines. This reaction is a contribution to green synthesis because it was performed electrochemically, in water, and without any metallic catalysts. Klíčová slova: furfural; 5-hydroxymethylfurfural; (di)amines Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural

Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into ...

Donkeng Dazie, Joel; Koláčná, Lucie; Urban, Jiří; Lamač, Martin; Ludvík, Jiří
Ústav fyzikální chemie J. Heyrovského, 2024

Electrochemical Properties of Newly Synthesized Selaginpulvilins
Dostálová, L.; Sokolová, Romana; Schwarzová-Pecková, K.; Rýček, L.
2024 - anglický
The electrochemical properties of newly synthesized selaginpulvilin were investigated by cyclic voltammetry and UV-Vis spectroelectrochemistry. The subject of the study were two\nselaginpulvilins differing in the presence of a hydroxyl group in the media of 0.1 mol L-1 tetrabutylammonium hexafluorophosphate as supporting electrolyte in anhydrous acetonitrile. Both\ncompounds provided an oxidative signal in the positive region until +2.0 V. Klíčová slova: oxidation; cyclic voltammetry; selaginpulvilins Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Properties of Newly Synthesized Selaginpulvilins

The electrochemical properties of newly synthesized selaginpulvilin were investigated by cyclic voltammetry and UV-Vis spectroelectrochemistry. The subject of the study were two\nselaginpulvilins ...

Dostálová, L.; Sokolová, Romana; Schwarzová-Pecková, K.; Rýček, L.
Ústav fyzikální chemie J. Heyrovského, 2024

3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics
Vaněčková, Eva; Sebechlebská, Táňa; Kolivoška, Viliam
2024 - anglický
3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The development of printable electrically conductive composite materials brought a revolution to electrochemistry, with 3D-printed electrodes being intensively studied from the viewpoint of\nanalytical performance and stability. However, it is often reported that 3D-printed electrodes have poor charge transfer characteristics, typically due to limited exposure of the electrically conductive phase at the composite surface to the surrounding solution. In this work, we devise and apply simple electrochemical activation procedures that lead to a significant improvement of charge transfer characteristics of 3D printed electrodes. Klíčová slova: three-dimensional printing; electrochemistry; electrodes Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics

3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The ...

Vaněčková, Eva; Sebechlebská, Táňa; Kolivoška, Viliam
Ústav fyzikální chemie J. Heyrovského, 2024

Metody úprav čistírenských kalů pro aplikaci v zemědělství s ohledem na mikropolutanty
Vítková, M.; Komárek, M.; Wickramasinghe, N.; Pohořelý, Michael; Moško, Jaroslav; Hušek, Matěj; Cajthaml, Tomáš; Grasserová, Alena; Čechmánková, J.; Vácha, R.; Zimová, M.
2024 - český
Cílem předkládané metodiky je popsat možnosti úpravy čistírenských kalů kompostováním a pyrolýzou pro aplikaci v zemědělství, a to zejména s ohledem na tzv. mikropolutanty, ale i na konvenční polutanty, a posoudit rizika upravených kalů pro půdní prostředí a vstup (mikro)polutantů do pěstovaných plodin. Metodika vychází z výsledků laboratorních a terénních experimentů tříletého projektu a z kritického přístupu ke kalům jako potenciálně nebezpečnému odpadu na straně jedné a recyklovatelného zdroje živin na straně druhé. The aim of the methodology is to describe the possibilities of sewage sludge treatment by composting and pyrolysis for the application in agriculture, with particular respect to the so-called micropollutants, but also to conventional pollutants, and to assess the risks of treated sludge for the soil environment and the uptake of (micro)pollutants by cultivated crops. The methodology is based on the results from laboratory and field experiments of a three-year project and on a critical approach to sludge as a potentially hazardous waste on the one hand and a recyclable source of nutrients on the other. Klíčová slova: pyrolysi; composting; emerging pollutants; soil; plant uptake; leaching Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Metody úprav čistírenských kalů pro aplikaci v zemědělství s ohledem na mikropolutanty

Cílem předkládané metodiky je popsat možnosti úpravy čistírenských kalů kompostováním a pyrolýzou pro aplikaci v zemědělství, a to zejména s ohledem na tzv. mikropolutanty, ale i na konvenční ...

Vítková, M.; Komárek, M.; Wickramasinghe, N.; Pohořelý, Michael; Moško, Jaroslav; Hušek, Matěj; Cajthaml, Tomáš; Grasserová, Alena; Čechmánková, J.; Vácha, R.; Zimová, M.
Ústav chemických procesů, 2024

Reaction Mechanisms of Psychoactive Compounds
Sokolová, Romana; Beneš, Marek; Jiroušková, Eliška; Degano, I.
2024 - anglický
The reaction mechanism of selected new psychoactive substances (NPS) 4-methylpentedrone and 2-(((4-ethyl-2,5-dimethoxyphenethyl)amino)methyl)phenol was investigated based on their\nelectrochemical and spectroelectrochemical properties. Both drugs were examined by means of cyclic voltammetry using diagnostic parameters for particular reaction schemes, UV/Vis, and IR\nspectroelectrochemistry. Since water participates in the redox mechanism of both studied compounds, the reaction mechanism was studied under a controlled amount of water in an\nacetonitrile environment. Klíčová slova: oxidation; reduction; IR spectrochemistry Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Reaction Mechanisms of Psychoactive Compounds

The reaction mechanism of selected new psychoactive substances (NPS) 4-methylpentedrone and 2-(((4-ethyl-2,5-dimethoxyphenethyl)amino)methyl)phenol was investigated based on their\nelectrochemical and ...

Sokolová, Romana; Beneš, Marek; Jiroušková, Eliška; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2024

Spectroelectrochemical Devices for Monitoring of Intermediates and Products on Carbonbased Composite Electrodes
Vaněčková, Eva; Šikula, M.; Hrdlička, Vojtěch; Sebechlebská, Táňa; Kolivoška, Viliam
2024 - anglický
Spectroelectrochemistry (SEC), as an interdisciplinary field, provides us with more comprehensive information about electroactive molecules involved in charge transfer reactions. Commercially\navailable SEC cells most often have an incorporated platinum working electrode, which can limit the range of the usable potential window and, in addition, can complicate the analysis due to the\nabsorption phenomenon. In this work, we designed and manufactured two types of custom-made SEC cells employing optically transparent carbon-based working electrodes for UV-Vis monitoring of reactants and electrogenerated intermediates and products. The first SEC cell is entirely manufactured by 3D printing using fused deposition modeling (FDM) by combining optically transparent (PET) and electrically conductive (PLA-CB) filaments. The second SEC cell employs pencil graphite (PG) rods as the working electrode (PGE) and its body is manually assembled from quartz slides. The functionality of the FDM 3D printed SEC cell and manually assembled quartz SEC cell were verified by cyclic voltammetry with in situ UV-Vis spectroscopic absorption monitoring of ruthenium(III) acetylacetonate (Ru(ac)3) redox-active probe dissolved in an aqueous or non-aqueous deaerated solvent, respectively. Both presented cells enable complete redox reversible conversion and strictly oxygen-free conditions. Klíčová slova: pencil graphite electrode; spectroelectrochemistry; 3D printed electrode Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Spectroelectrochemical Devices for Monitoring of Intermediates and Products on Carbonbased Composite Electrodes

Spectroelectrochemistry (SEC), as an interdisciplinary field, provides us with more comprehensive information about electroactive molecules involved in charge transfer reactions. ...

Vaněčková, Eva; Šikula, M.; Hrdlička, Vojtěch; Sebechlebská, Táňa; Kolivoška, Viliam
Ústav fyzikální chemie J. Heyrovského, 2024

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