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Kinetics of benzo[a]pyrene destruction and identification of its products
Ryšavý, Jan ; Kolek, Emil (referee) ; Šimko, Peter (advisor)
This diploma thesis is focused on the study of conditions of benzo[a]pyrene, one of the major contaminant of foods, photodegradation under different conditions (solvents with different polarity, light sources, presence of antioxidants). In another part of the thesis, the degradation process of benzo[a]pyrene at various concentrations was studied, in order to characterise the kinetic aspects of photoinduced degradation. The attempt to identify the products of benzo[a]pyrene photodegradation was performed involving methods of gas chromatography and high performance liquid chromatography coupled with mass detectors, as well.
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Biodegradable bones implants based on iron
Hrabovský, Jan ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This work deals with a current topic, which are biodegradable bone implants. These implants seem to be a suitable candidate for temporary fixations, with their gradual decomposition. An important parameter is not only the mechanical properties so that the material can withstand the load, but above all the corrosion properties and the degradation process. This work introduces the physiology of bone, trace elements and also describes current trends in the field of implants. The last part is a theoretical introduction to cross-stage processes. The practical part is focused on the preparation of iron-based samples with various dopants, subsequent annealing and analysis.
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Coating properties of cutting tools carbide
Doležalová, Petra ; Bumbálek, Bohumil (referee) ; Osička, Karel (advisor)
Diploma thesis is divided into two parts. The first part is focused on theoretical description of coating methods, on currently used coatings, their properties and it is also focused on description of methods, which are used for analyzing each property. The second part focuses on testing of coatings and analyzing of the values obtained from experiments. The aim of this thesis is then to compare the properties of the tested coatings.
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Reoxidation in steel
Kotásek, Petr ; Veselý, Pavel (referee) ; Šenberger, Jaroslav (advisor)
This work is about development and methodology verification of data collection which will be used in the research of the reoxidation in steel castings. To examine reoxidation rate will be measured oxygen activity in the furnace, in the ladle and in the mould. Next it will be evaluated the chemical structure of mould slag, the chemical changes of steel and measured the volume and the area of the casting defects. Each technique is briefly described by the principle of measurement and each method has the results which are analysed. In the conclusion the experiment is summarized and there are mentioned the observations from this experiment.
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Study of AlSi protective coating after degradation
Vítková, Gabriela ; Řičánková, Veronika (referee) ; Hutařová, Simona (advisor)
Materials used for high temperature applications works in a very aggressive environment (oxidation, hot corrosion, erosion, fatigue, creep). Demands on these materials are very high. Nickel-based superalloys show the certain stability in this environment. Improved resistance to oxidation and hot corrosion can be achieved by using protective layers such as diffusion barriers. This thesis is focused on changes of microstructure and properties of AlSi layer applied by „slurry“ method on nickel-based superalloy Inconel 713 LC, due to long-term thermal exposition at 800, 900 a 1000 °C.
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Analysis of usage hydrogen in power supply
Krček, Martin ; Ptáček, Michal (referee) ; Radil, Lukáš (advisor)
The work deals with harnessing the hydrogen in electricity production. It surveys hydrogen production, storage, transportation and its use as power source for fuel cells and combustion turbines. Characteristics of a hydrogen production electrolyzer were gauged in laboratory and its efficiency was evaluated.
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Elimination of degradation processes of metallic thin films
Danovič, Jakub ; Šubarda, Jiří (referee) ; Šimonová, Lucie (advisor)
This work deals with issues of thin films, their behaviour in different enviroments and protection of theese films against unwanted degradation processes. Metal thin films are made by special physical or chemical methods in the presence of vacuum. Deposition is performed on properly cleaned substrate made of different materials, for example glass, ceramics or another metal. Theese films degrades under the influence of moisture, heat and other. There are several types of films on different bases made to prevent thin films against degradation.
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Testing of polymeric materials under climatic conditions of Antarctica
Mičkal, Petr ; Sluková, Michaela (referee) ; Krmíček, Lukáš (advisor)
The bachelor's thesis generally deals with polymer materials and evaluates the possibility of testing their resistance to extreme climates of Antarctica. Described herein are various polymer materials, their characteristics, structure, properties and more thorough and detailed descriptions of selected polymers. The next section describes the basic types of degradation these polymers are exposed to, when facing the extreme conditions of the Antarctic climate. The practical part contains evaluations of tests made on the degraded polymer materials that were collected in Antarctica during the southern Antarctic season of 2013-2014 by Ing. Bc. Pavel Kapler, Ph.D, who is a superintendent at the Czech scientific station JG Mendel.
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Tribotechnická diagnostika prvonáplní motorového oleje z motorů osobních automobilů
Prokeš, David
The master thesis Tribotechnical diagnostics of first-fill engine oil from passenger car engines deals with the composition, production, distribution, wear and tear, specification of passenger car engine oils and their diagnostics and evaluation during use and wear. The research part of the thesis deals with the classification of lubricants and their brief description, classification of engine oils and a brief description of their manufacture. Subsequently, the basic concepts related to the above topic are described. The experimental part of the thesis deals with the methodology, material and actual measurement of selected parameters for the assessment of engine oil condition during engine break-in of new passenger cars. The selected indicators are the amount and morphology of particles, determination of the water content of engine oil, alkaline reserve, oxidation and additive content. The following diagnosis of the condition of the primary engine oil confirmed the assumption of a higher content of wear metals. An interesting result was the detection of higher oxidation rates in engine oils, which may be a consequence of long storage periods before the car is sold.
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Development of Electrochemical Thin-layer Degradation Cell for Oxidation Stress Testing of Active Pharmaceutical Ingredients
Šefčík, Martin ; Kubíčková, Anna (advisor) ; Coufal, Pavel (referee)
In this thesis, the oxidation conditions in a new electrochemical "thin-layer" flow-through cell for the study of the oxidative degradation of active pharmaceutical ingredients were optimized. In this field, it is an innovative approach to studying the oxidation properties of substances. The cell was manufactured using 3D printing technology. Oxidation was carried out in a two-electrode arrangement with a working boron-doped diamond electrode (BDDE) and an auxiliary stainless steel electrode. Optimization of conditions was performed using salicylic acid as a model active pharmaceutical ingredient. The electrochemical approach was used to degrade this active pharmaceutical ingredient by the required approximately 20% of the original amount in only 2.3 min. Thus, the degradation time was significantly reduced compared to the oxidative stability stress tests of active pharmaceutical ingredients commonly used today. Two major degradation products were observed, namely gentisic acid and 2,3-dihydroxybenzoic acid. The degradation products obtained by electrochemical oxidation and chemical oxidation using hydrogen peroxide are identical.
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