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Self-sensing properties of alkali-activated slag composites under compressive loading
Míková, Maria ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
Production of construction materials requires a large amount of energy. That can be decreased by using of waste materials. This thesis deals with the self-sensing properties of composites. It presents electrical properties of building materials and their measurement. In the experimental part, the influence of conductive fillers on the self-sensing properties of aluminosilicate composites was examined. Test cubes were made of alkali-activated slag with a content of graphite powder, carbon black, carbon fibers, steel fibers or carbon nanotubes. The fractional change in resistence during cyclic compressive loading was monitored.
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Carbon nanotubes utilization for fabrication of thick-film sensors electrodes
Polický, Jiří ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work covers an area of heavy metals detection by miniaturized thick film sensors. Working electrode of these sensors was fabricated using thick film paste that was prepared as a nanocomposition of carbon nanotubes powder, suitable vehicle and a thinner. The response of fabricated electrodes to cadmium and lead ions was measured using differential pulse voltammetry in an acetate buffer solution using a three electrode sytem. The results were compared with the carbon electrode made from special commercial thick film polymer paste. Finally the possibility of working electrode surface activation with nitric acid and heavy metals on real biological sample detection is described here.
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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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Tin dioxide based semiconducting gas sensors
Gablech, Imrich ; Pytlíček, Zdeněk (referee) ; Prášek, Jan (advisor)
This project is aimed at semiconductive gas sensors based on tin dioxide. In the first part, gas sensors are divided depending on their principal of functionality. Next part is about functionality of tin dioxide gas sensors and the possibilities of active layer modification. Experimental describes gas sensor from its drawing until construction, testing and characterization. Several microelectronic technologies such as thin-film, thick-film, LTCC, spray-coating or wire-bonding were used for constructing the sensor. In the last part properties of gas sensors and differences in functionality between modified and unmodified gas sensor are summarized.
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Research of effective use and activation of activ concrete additions
Mikhailova, Olesia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The theoretical part describes the admixtures that are used in cement replacement. Here also summarizes the findings on the influence of granulomentry, grain shape and fineness of admixtures on the density of the cement matrix. The practical part is experimentally verified the influence of fineness admixtures and grain size on the mechanical properties of concrete. Also, the rheological properties of cement are compared with admixtures depending on the type and dosage and time.
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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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Electrochemical biosensor for the study of DNA methylation
Petrula, Jakub ; Hrdý, Radim (referee) ; Hynek, David (advisor)
This bachelor’s thesis deals with design and optimalisation of custom biosensor for detection of methylated DNA. Teoretical part explains the mechanism and importance of DNA methylation. Next section describes analytical methods used in connection with DNA methylation and some basic direct and indirect methods of detection. Final part is dedicated to experiment itself, which is divided into several sections. Section one deals witch modification of working electrode and optimalisation of detection method. Second section introduces two different ways of DNA methylation detection. First is based on direct detection and second one on detection through the biosensor. Final part shows determination of methylcytosine from sample based on analysing characteristic attributes of signal and numeric algorithm based on curve fitting.
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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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