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Study of gas influence on nanoparticle generation by electrical discharge in liquids
Simić, Sanja ; Horák, Jakub (referee) ; Kozáková, Zdenka (advisor)
The work is focused on the preparation and characterization of Ag nanoparticles generated by plasma of the electric discharge in liquids. In more detail, it examines the DC discharge and the formation of hydroxyl and hydrogen radicals. The process is chemical in situ reduction, which is one of the most important methods of producing Ag nanoparticles because it is simple and economical and can perform better dimension size control by optimizing experimental parameters. During experiments, changes were made in various parameters such as concentration, conductivity, solution pH, intensity and polarity of the applied voltage. Different parameters such as particle size, shape, specific surface, crystallinity and many others can affect the properties of the nanoparticles. In view of these facts, detailed analysis of both plasma and nanoparticles generated for the control of nanoparticle synthesis and subsequent application is essential. In this work a plasma analysis was performed by optical emission spectroscopy (OES) and the characteristics of nanoparticles by UV-VIS spectroscopy and scanning electron microscopy (SEM). Silver nanoparticles are used in many industries such as the food, textile, construction and energy industries as well as in medicine, cosmetology and pharmacy. Thanks to their widespread use they represent the future of nanotechnology.
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Plasma chemical deposition of thin polymer layers based on 2-ethyl-2-oxazoline and their diagnostics
Podzemná, Erika ; Horák, Jakub (referee) ; Mazánková, Věra (advisor)
Medical devices are often subject to the colonisation of bacteria, making it a prerequisite for infection in the patient's body. To prevent biofilm, the medical device can be covered with a thin layer of polymeric substance that has the ability to prevent biological fouling. In this work, was selected 2-ethyl-2-oxazoline as a precursor for the formation of thin polymer layers. In general, the oxazoline group is known for its antibacterial and biocompatible properties, which is the reason for choosing this substance. The main objective of this thesis was the deposition of thin polymer films, which are based on 2-ethyl-2-oxazoline, in surface dielectric barrier discharge under atmospheric pressure. The principle of thin layer formation on a teflon substrate is plasma polymerization. The preparation of the layers was followed by their characterization by several methods. Their physical and chemical properties were studied using SEM, FTIR, and by measuring the contact angles of the surface of the layers. Furthermore, the processes that take place in plasma, when there is an interaction of electrons and ions with the monomer molecule, were investigated. Ion mobility spectrometry and the crossed-beam ionization method were used for this measurement. The layers were also tested for their antibacterial and cytocompatible properties.
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Barier Coatings based on Polyparaxylylene for the Space Research Applications
Horák, Jakub ; Zahoranová, Anna (referee) ; Mráček, Aleš (referee) ; Krčma, František (advisor)
Titan, a moon of the planet Saturn, is interesting to many researchers for its thick atmosphere, which, like its surface, is composed mainly of nitrogen (95%) and methane (5%) with various hydrocarbons, and thanks to the conditions that prevail on Titan, it is considered to be a model of Earth in the time before the origin of life. In order to be able to monitor the processes that take place on various space bodies, it is necessary to successfully transfer a space probe to them and thoroughly protect the electronics, which is affected by many adverse effects during takeoff, flight and landing, like thermal fluctuations, various radiation or the atmosphere of the space body to which the electronics may be exposed if the integrity of the probe shell is compromised (for example, in the case of landing modules). Parylene layers are already used in space research, and the aim of this work is a deeper understanding of the changes of their mechanical, chemical and physical properties after their exposure to the simulated atmosphere of Titan and UV radiation. Two thickness sets of parylene layers (2 and 6 µm) were prepared, which were subsequently exposed to the influence of a simulated atmosphere with a methane content of 1, 3 and 5% – at laboratory and reduced temperatures (cooling with liquid nitrogen). In each set, the samples were always duplicated, thanks to which we obtained two sets of samples – the first was affected only by the conditions used in the simulation of atmospheric events on Titan (reaction products and the used discharge) and the second set, which was additionally degraded using UV radiation (possible influence of photons). The effect of such treatments was characterized using FTIR and other analytical methods. It turns out that even when exposed to the conditions of the simulated atmosphere, photooxidation occurs for most of the samples exposed to the mixture with the highest methane content. For some samples, this led to a reduction of a subsequent effect of applied UV radiation, which is probably the result of the parylene layer cross-linking. AFM confirmed that the reactions taking place on the layers during the simulation of the atmosphere increase their roughness, and that after exposure to UV radiation, the layers exposed to Titan's atmosphere at laboratory and reduced temperatures exhibit strong surface degradation. This was also confirmed during nanoindentation, where the layers without the influence of secondary UV radiation did not show an increase in hardness or elastic modulus, while after UV irradiation the values were almost doubled, and their uncertainties also increased significantly. The strong degradation effect of the applied UV radiation was observed by SEM as well – these samples were almost impossible to measure due to the strong charging and visible in-situ deformation by the used electron beam. The work also included the synthesis of silver and copper nanoparticles for their later targeted incorporation into parylene layers. Nanoparticles were prepared by using electrical discharge in liquids. While the silver nanoparticles were metallic and spherical in shape, a nanowhiskers structure and significant agglomeration were observed for the copper-based particles; their surface was not metallic but formed of oxides/hydroxides. The direct application of nanoparticles into the parylene layers could not be implemented, yet.
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Effects of electrical discharges on the Mars´ atmosphere
Fojtíková, Nikola ; Horák, Jakub (referee) ; Kozáková, Zdenka (advisor)
The aim of this thesis was to study the effects of electric discharge on the atmosphere simu-lating conditions on Mars. This bachelor thesis is focused on simulation of Mars atmosphere at atmospheric pressure and normal laboratory temperature. Mars's atmosphere was more like Earth in the past. Mars is mostly composed of carbon dioxide, which accounts for more than 90% of Mars' atmosphere. To study the Mars atmosphere simulation, glow discharge generated in the reactor at atmospheric pressure was used at a CO2 flow (100 sccm) and dis-charge current of 20, 30 and 40 mA. A part of the measurements was focused on the influ-ence of hydrogen addition at different flow rates. The measurement time course with differ-ent measurement changes was also recorded. Reaction products were analysed using a pro-ton ion mass spectrometer and a flight time analyser. A high amount of aliphatic hydrocar-bons and their derivates, especially alcohols, was detected as well as several cyclic struc-tures. The main products identified in all experiments with a substantial concentration were molecules of ethen, ethane, ethanol, acetone, pentane, benzene and others.
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Study of gas influence on nanoparticle generation by electrical discharge in liquids
Simić, Sanja ; Horák, Jakub (referee) ; Kozáková, Zdenka (advisor)
The work is focused on the preparation and characterization of Ag nanoparticles generated by plasma of the electric discharge in liquids. In more detail, it examines the DC discharge and the formation of hydroxyl and hydrogen radicals. The process is chemical in situ reduction, which is one of the most important methods of producing Ag nanoparticles because it is simple and economical and can perform better dimension size control by optimizing experimental parameters. During experiments, changes were made in various parameters such as concentration, conductivity, solution pH, intensity and polarity of the applied voltage. Different parameters such as particle size, shape, specific surface, crystallinity and many others can affect the properties of the nanoparticles. In view of these facts, detailed analysis of both plasma and nanoparticles generated for the control of nanoparticle synthesis and subsequent application is essential. In this work a plasma analysis was performed by optical emission spectroscopy (OES) and the characteristics of nanoparticles by UV-VIS spectroscopy and scanning electron microscopy (SEM). Silver nanoparticles are used in many industries such as the food, textile, construction and energy industries as well as in medicine, cosmetology and pharmacy. Thanks to their widespread use they represent the future of nanotechnology.
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Generation of nanoparticles by electrical discharge in liquids
Čechová, Ludmila ; Horák, Jakub (referee) ; Kozáková, Zdenka (advisor)
This thesis focuses on the process of nanoparticle generation by electric discharge in liquids. The theoretical part is focused on generation of electric discharge in liquids, various methods of preparation of nanoparticles, including plasmachemical methods and methods of nanoparticle characterization. The experimental part deals with the preparation of silver nanoparticles. As a precursor for generation of nanoparticles by electric discharge, an aqueous solution of silver nitrate was used. The influence of experimental conditions, such as the influence of voltage polarity, influence of delivered power, effect of concentration, effect of added electrolyte and time course of nanoparticle formation were studied. All samples were analyzed by UV-VIS spectrometry. To confirm the presence of nanoparticles in the solution, one of the samples was analyzed by a scanning electron microscope with an energy dispersion spectrometer for elemental analysis. Plasma diagnostics was performed using optical emission spectroscopy.
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Control of Embedded System Through Internet
Horák, Jakub ; Podivínský, Jakub (referee) ; Dobai, Roland (advisor)
The goal of this bachelor thesis is to enable a regular user to control the embedded system on Xilinx Zynq, which will include audio codec ADAU1761. In the thesis I will describe what is required to connect the device to the Xilinx Zynq platform. After that, the device’s control through Internet will be described, followed by the design and implementation of an application that will allow the user to interact with the device.
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