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Yes (11)
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Electrochemical Study of the Supported Iron Oxide Catalysts
Gál, M.; Horváth, B.; Navrátil, Tomáš
2018 - English
Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this short contribution we tried to characterize supported iron(III) oxide\ncatalyst with different amount of Fe and to find an optimal iron(III) oxide content for the best\ncatalysts performance. The importance of phase quality on the selectivity of respective\ncatalysts samples is also discussed. Linear sweep voltammetry was chosen for this purpose.\nResults obtained by electrochemical methods are compared with efficiency (selectivity) of\nrespective catalysts.
Keywords:
Catalyst; Linear sweep voltammetry; Propylene oxide
Available on request at various institutes of the ASCR
Electrochemical Study of the Supported Iron Oxide Catalysts
Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this ...
HPLC-ED/UV with Solid Phase Extraction for the Determination of 5-Hydroxyindole-3-acetic Acid
Němečková-Makrlíková, Anna; Dejmková, H.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2018 - English
Determination of 5-HIAA in human urine was successfully performed using HPLC-ED/UV with SPE. HPLC-ED is a very sensitive technique, presented method does not need any sample pre-treatment apart from SPE procedure, which replaced filtration of samples of human urine to avoid problems with clogging a HPLC column. The found native\nconcentrations of 5-HIAA in human urine using HPLC-ED with SPE fully corresponds with published normal concentrations in urine (17.8 - 58.3 micromol l-1). The found native concentrations of 5-HIAA were 18.4 micromol L-1 (calculated from peak height). The presented method is fast and could be used for simple\nscreening of human urine, because HPLC-ED/UV allows simultaneous determination of 5-HIAA, HVA, and VMA as important tumour biomarkers.
Keywords:
HPLC; electrochemical detection; spectrophotometric detection
Available on request at various institutes of the ASCR
HPLC-ED/UV with Solid Phase Extraction for the Determination of 5-Hydroxyindole-3-acetic Acid
Determination of 5-HIAA in human urine was successfully performed using HPLC-ED/UV with SPE. HPLC-ED is a very sensitive technique, presented method does not need any sample pre-treatment apart from ...
Introducing Functionality by Graphene Covalent Grafting
Kovaříček, Petr; Kalbáč, Martin
2018 - English
Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent functionalization. We have exploited protocols for surface grafting by diazonium salts, by nucleophilic and electrophilic substitution to perform graphene covalent modification of graphene on substrates. The painstaking analysis problem of monolayered materials was addressed using Raman spectroscopy, SERS, SEIRA, MS, AFM, XPS and SEM/EDX. The covalent grafting was shown to tolerate the transfer process, thus allowing ex post transfer from copper to other substrates. Functional devices often require combination of several materials with specific functions, such as graphene-polymer hybrid heterostructures. We have used the developed methodology of chemical functionalization for preparation of PEDOT:Graphene bilayers by selective in situ polymerization of EDOT on covalently functionalized graphene. The polymerization proceeds exclusively on the grafted graphene, and patterned structures with high spatial resolution down to 3 μm could have been prepared. The composite exhibits enhanced efficiency of electrochemical doping compared to pristine graphene, unsymmetrical transport characteristic with very good hole-transporting properties and efficient electronic communication between the two materials. The covalent functionalization of graphene thus introduces advanced functionality to the material, broadening its scope of applications.
Keywords:
graphene; covalent functionalization; PEDOT
Available at various institutes of the ASCR
Introducing Functionality by Graphene Covalent Grafting
Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent ...
HPLC-ED/UV for determination of vanillylmandelic acid in human urine after solid phase extraction
Němečková-Makrlíková, Anna; Dejmková, H.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2018 - English
HPLC with electrochemical and spectrophotometric detection (ED/UV) after solid phase extraction (SPE) was used for determination of vanillylmandelic acid in human urine. HPLC-ED was performed at a glassy carbon electrode in a “wall-jet” arrangement in acetate-phosphate buffer at pH = 2.5 and gradient elution (increasing content of\nacetonitrile from 5 to 25% in 10 minutes) was used. Optimized parameters were following: flow rate of mobile phase 1 mL min−1, detection potential +1.1 V, detection wavelength 279 nm, injected volume 20 μL. Dependence of the peak current on the analyte concentration was linear in the concentration range from 10 to 150 μmol L−1, with obtained limits of detection 2.6 μmol L−1 (calculated from peak height) and 1.9 μmol L−1 (calculated from peak area) for HPLC-ED, and 11.0 μmol L−1 (calculated from peak height) and 9.8 μmol L−1 (calculated from peak area) for HPLC-UV.
Keywords:
HPLC; solid phase extraction; tumor biomarker
Available on request at various institutes of the ASCR
HPLC-ED/UV for determination of vanillylmandelic acid in human urine after solid phase extraction
HPLC with electrochemical and spectrophotometric detection (ED/UV) after solid phase extraction (SPE) was used for determination of vanillylmandelic acid in human urine. HPLC-ED was performed at a ...
Investigation of Single Molecule Charge Transport Properties and Geometrical Arrangement in Terpyridine Architectures Supported by the Tetraphenylmethane Tripod
Kolivoška, Viliam; Sebechlebská, Táňa; Šebera, Jakub; Gasior, Jindřich; Lindner, M.; Lukášek, J.; Valášek, M.; Mayor, M.; Mészáros, G.; Hromadová, Magdaléna
2018 - English
Tripodal platforms were engineered recently to realize a well-defined directional contact between metallic electrodes and molecular architectures dedicated to serve as working elements for electronic applications. In this work we employ cyclic voltammetry, scanning tunneling microscopy break junction technique and theoretical approaches based on the combination of density functional theory and non-equilibrium Green´s function to investigate the geometrical arrangement and single molecule charge transport in terpyridine-based architectures supported by tetraphenylmethane tripod. We demonstrate that this architecture adopts a favorable geometrical arrangement capable of forming highly conductive molecular junctions and is thus suitable to serve as a basis for working molecular switches.
Keywords:
molecular electronics; Molecular conductors and switches; Tripodal platforms
Available on request at various institutes of the ASCR
Investigation of Single Molecule Charge Transport Properties and Geometrical Arrangement in Terpyridine Architectures Supported by the Tetraphenylmethane Tripod
Tripodal platforms were engineered recently to realize a well-defined directional contact between metallic electrodes and molecular architectures dedicated to serve as working elements for electronic ...
Influence of Adsorption on Electrochemical Reduction of Pyridinium Derivatives
Nováková Lachmanová, Štěpánka; Dupeyre, G.; Lainé, P. P.; Hromadová, Magdaléna
2018 - English
Two expanded pyridinium-based compounds 1 and 2 were studied by cyclic voltammetry in two different environments. The nonaqueous solution suppresses the adsorption of the compounds on the electrode surface. Adsorption process in aqueous environment was confirmed by typical shape of the curve as well as by the linear dependence of peak current on the scan rate. The shift of standard redox potential in aqueous solution compared to nonaqueous environment toward more negative potential indicates the adsorption of reactant on the electrode surface. Larger shift observed for flat conjugated molecule 1 confirms its stronger adsorption than for the second molecule.
Keywords:
pyridinium derivatives; adsorption; cyclic voltammetry
Available on request at various institutes of the ASCR
Influence of Adsorption on Electrochemical Reduction of Pyridinium Derivatives
Two expanded pyridinium-based compounds 1 and 2 were studied by cyclic voltammetry in two different environments. The nonaqueous solution suppresses the adsorption of the compounds on the electrode ...
Study of Metabolism of Synthetic Cannabinoids. Electrochemical Properties of JWH-018
Obluková, Michaela; Sokolová, Romana; Čabala, R.
2018 - English
In the recent years, many new substances have appeared in the drug market, which are abused for their psychoactive effect. They serve as alternative to classical drugs (heroin, cocaine, ecstasy) due to their legal status. The great concern is the ineffectiveness of the current methods of toxicological screening of biological samples to identify these new compounds. It is essential to know the metabolism pathway of these psychoactive substances for a development of a new efficient method for their detection. This report is devoted to understanding of oxidation and reduction mechanism of JWH-018 and JWH-250 by means of cyclic voltammetry and to identification of their redox products.
Keywords:
synthetic cannabinoids; metabolism; cyclic voltammetry
Available on request at various institutes of the ASCR
Study of Metabolism of Synthetic Cannabinoids. Electrochemical Properties of JWH-018
In the recent years, many new substances have appeared in the drug market, which are abused for their psychoactive effect. They serve as alternative to classical drugs (heroin, cocaine, ecstasy) due ...
Miniaturized Boron Doped Diamond Film Electrode for Neuroblastoma Biomarkers Determination
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš; Taylor, Andrew
2017 - English
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).
Keywords:
biomarkers; boron doped diamond film; voltammetry
Available on request at various institutes of the ASCR
Miniaturized Boron Doped Diamond Film Electrode for Neuroblastoma Biomarkers Determination
Cathodically pretreated miniaturized boron doped diamond film\nelectrode was successfully tested for the purposes of in-situ determination\nof neuroblastoma biomarkers after hollow-fibre ...
Supported Phospholipid Bilayer at the Conductive Interface
Sokolová, Romana; Kocábová, Jana; Kolivoška, Viliam; Gál, M.
2017 - English
The interactions of ethanol and flavonoid compounds with supported phospholipid bilayer\nwere studied by means of electrochemical methods and scanning probe techniques. The\nstability of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) phospholipid bilayer\nsupported on different types of conductive substrate was investigated. The relationship\nbetween the method of lipid deposition and the formation of several types of lipid structures\nincluding vesicles, hemimicelles, patches and single bilayers on the interface is discussed.
Keywords:
Supported phospholipid bilayer; Ethanol; Atomic force microscopy
Available on request at various institutes of the ASCR
Supported Phospholipid Bilayer at the Conductive Interface
The interactions of ethanol and flavonoid compounds with supported phospholipid bilayer\nwere studied by means of electrochemical methods and scanning probe techniques. The\nstability of a ...
Charge Transport through Molecular Towers Based on Tetraphenylmethane Tripods
Kolivoška, Viliam; Šebera, Jakub; Lindner, M.; Valášek, M.; Mayor, M.; Mészáros, G.; Gasior, Jindřich; Hromadová, Magdaléna
2017 - English
Molecular platforms with multiple anchors were introduced recently to provide robust\ncoupling between molecular electronic components and metallic electrodes. In this work,\ncharge transport in tower-shaped single molecule conductors based on tetraphenylmethane\ntripod possessing three thiol anchors is investigated by scanning tunneling microscopy break\njunction technique. The effect of tripod substitution pattern and number of repeating units in\nmolecule is addressed. The substitution was found to influence conductance value in early\nstages of molecular junction evolution, where tower lays parallel to surface. In late stages, the\ncharge is transported through principal molecular axis and junction breaks thermally in tilted\nconfiguration.
Keywords:
Charge Transport Through Single Molecules; Break Junction Technique; Molecular Electronics
Available on request at various institutes of the ASCR
Charge Transport through Molecular Towers Based on Tetraphenylmethane Tripods
Molecular platforms with multiple anchors were introduced recently to provide robust\ncoupling between molecular electronic components and metallic electrodes. In this work,\ncharge transport in ...
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