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Modification of electrochemical sensors working electrodes for biological substances detection
Weiss, Vojtěch ; Prášek, Jan (referee) ; Majzlíková, Petra (advisor)
The aim of this work is modification of working electrode surface of screen-printed electrochemical sensors using carbon nanotubes. General knowledge about sensors, their categorization, thick-film technology, properties, preparation and utilization of carbon nanotubes and selected electrochemical methods are reported in theoretical part. Three different methods of working electrodes modification with carbon nanotubes are described in the experimental part of the thesis. Furthermore characterization of modified and unmodified electrodes using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy is presented. All results are summarized and discussed in the conclusion of this work.
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Spray-coated working electrodes of electrochemical sensors
Lechner, Filip ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This thesis is about the selection of the better type of thick film working electrode for the detection of substances in aqueous solutions, modified by spray coated carbon nanotubes. The theoretical part of this thesis describes the technology of thick film, properties and production of carbon nanotubes, introduction to electrochemistry and electroanalytical methods for the detection of substances in aqueous solutions. The practical part is aimed to realization of the working electrodes by thick film technology and their modification by spray-coated layer consist of carbon nanotubes. Electrodes are characterized using voltammetric methods, electrochemical impedance spectroscopy and electron microscopy. In conclusions is selected the most suitable type of working electrodes for reproducible electrochemical analysis.
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Biosensors based on modified carbon nanotubes
Ferdusová, Helena ; Majzlík, Petr (referee) ; Hubálek, Jaromír (advisor)
The aim of this work is to describe biosensors for detection of substances in liquids using modified carbon nanotubes. This work reports on knowledge about nanotubes and electrochemical analysis methods which were used. The matter of direct electrochemical detection of insulin using CNTs modified thick layer planar carbon nanotubes is discussed. The elementary working electrodes were created by using of commercial carbon paste and were modified by thin film CNTs, CNTs/ruthenium oxide and CNTs/chitosan then. The best results of the insulin detection were achieved with the working electrodes modified by low concentration non-purified CNTs which had low elementary response in electrolyte and good response to increasing concentration of insulin in the concentration range from 0, 25 to 10 mol/L. The other modifications caused increasing of the electrode elementary response, but they did not significantly affect the detection.
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Thick-film sensors for electrochemical detection of species in aqueous solutions
Martynek, Daniel ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work deals with the theory, principles and characteristics of electrochemical sensors, thick-film technology and electrodes used in electrochemistry. Methods for the detection of substances matters in solutions are discussed here. Main emphasis is given to differential pulse voltammetry and the influence of the method setup parameters to the measurement results. Experimentally, the work deals with the modification of thick-film working electrode with carbon nanotubes and subsequent activation of the electrode by nitric acid to increase the detection limit and the current response to selected heavy metals ions. Finally, the obtained results are compared with special commercial paste and discussed with the data state in literature.
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Characterization of 1-D Nanostructures by SPM Methods
Škoda, David ; Čech, Vladimír (referee) ; Pavlík, Jaroslav (referee) ; Dub, Petr (advisor)
The thesis is aimed at the characterization of carbon nanotubes and silver nanowires by Scanning Probe Microscopy, namely Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM), Conductive AFM (CAFM) and Scanning Near-Field Optical Microscopy (SNOM). Carbon nanotubes were analyzed by STM, AFM and CAFM microscopy. In a designed apparatus the silver nanowires were fabricated by template assisted deposition and were analyzed with respect to their geometry (AFM), local conductivity (CAFM) and optical properties (SNOM, microreflex spectroscopy). It was found that preferential type of carbon nanowires depends on the fabrication process. The measurements of local conductivity of the nanotubes revealed the similarity with the STM measurements. The AFM measurements of silver nanowires confirmed their growth inside the pores of polycarbonate template. Single nanowires exhibits the semiconducting behavior according to I--V measurement and localized plasmon resonances.
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Interlaminar fracture toughness of fiber reinforced plastics
Vodička, Vít ; Mališ, Michal (referee) ; Klement, Josef (advisor)
Cílem této diplomové práce je lépe porozumět konceptu únavového poškození damage tolerance zmapováním všech možných vlivů na lomovou houževnatost vláknového kompozitu s polymerní matricí. Toho je dosaženo provedením zkoušek za různých podmínek (např. změna parametrů měření, mód zatížení, pořadí vrstev a materiál) a monitorováním odlišností v šíření trhliny. Na základě dat získaných během těchto testů je určena lomová houževnatost. Potenciální rozdíly jsou zkonzultovány a porovnány s ostatními vzorky.
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Design of the fluorescence microscope for carbon nanotubes spectroscopy
Borovský, Ján ; Novotný,, Karel (referee) ; Novotný, Jan (advisor)
This diploma thesis deals with design, implementation and testing of fluorescence microscope intended for carbon nanotubes spectroscopy. Theory of fluorescence resulting from solid state physics and atomic structure of nanotubes is briefly discussed. The basic idea, optical scheme and optical elements used in the fluorescence microscope are described based on requirements resulting from the theory. The thesis mentions the sample preparation procedure and measurements of its optical activity as well. Realized microscope is usable for fluorescence measurements within the supposed range of wavelengths as was proved by testing.
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Study of catalytic activity of ceramic perovskite materials for energy applications
Schlosser, Radek ; Cihlář, Jaroslav (referee) ; Cihlář, Jaroslav (advisor)
In this diploma thesis the preparation of ceramic catalytic materials was studied. They were studied by means of catalytic activity on powder samples and in a form of membrane as well. At first were multicomponent perovskite materials with the help of “glycine-nitride synthesis” synthesized. Two types of perovskite systems were prepared. First system was on the basis of nickelates LaNiO3 and the second one on the basis of cobaltites SmCoO3. Both of them were doped with aluminium and calcium. Ceramic powders were catalytic tested during reformed reaction. A part of powders was pressed with hydraulic biaxial press. Then the membranes were calcinated, sintered and polished. The membranes were tested to specify the catalytic activity. At first they were in hydrogen atmosphere reduced and afterwards came through the partial oxidation. The appearance of coke fibers on the surface was discussed.
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Effect of curing conditions on the properties of alkali activated slag
Rypák, Peter ; Bayer, Patrik (referee) ; Rovnaník, Pavel (advisor)
Combination of fine ground granulated slag with proper alkaline activator gives alkali-activated slag – a material with remarkable properties. Theoretical part of the thesis deals with summarizing basic informations about alkali-activated slag, its properties, production and utilization. It also follows research devoted to effects of curing of alkali activated slag and shrinkage-reducing admixtures on its properties. Objective of the experimental part is to determine the influence of curing conditions on the mechanical properties and microstructure of alkali-activated slag. These properties are also monitored in alkali-activated slag with carbon nanotubes and hydroxypropylmethylcellulose as an shrinkage-reducing admixtures.
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