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Mechanism of the formation of Antarctic ozone depletion
Fryčová, Kateřina ; Přibil, Rudolf (advisor) ; Havlíček, David (referee)
Antarctic ozone hole is so serious environmental problem that has become a subject of study of many scientists and studies. Thanks to them were studied in detail not only the chemical reactions taking place in the stratosphere, but also very specific climatic conditions prevailing over Antarctica, which is why the emergence of the ozone hole was there. The aim of this paper is to summarize the findings and conclusions achieved in these areas of research. The first third is devoted to general description of ozone, its characteristics, division into the tropospheric and stratospheric, chemical reactions in these parts of atmosphere which leads to the formation and dissolution of ozone. Then pay attention to how these natural processes to affect manmade compounds - CFCs and the characteristics of these substances. The next section analyzes the specifics of climate prevailing over Antarctica, how to intervene in the chemical processes in sratosphere, by extension, what their overall share of the damage ozonosphere and of course there are also mentioned chemical reactions leading the biggest ozone depletion. Lastly, are also mentioned legislative measures which man has taken in order to protect the ozone layer, the contemporary situation and outlook and that the implications of a weakening of the ozone layer for...
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Quantitative analysis by X-Ray powder diffraction
Stachová, Sandra ; Havlíček, David (advisor) ; Vojtíšek, Pavel (referee)
Quantitative analysis methods using X-ray powder diffraction are still highly actual conception in the area of research of modern materials. The Reference Intensity Ratio (RIR) method is used here for quantitative analysis by X-ray powder diffraction of model samples in this bachelor thesis. The model samples are three mixtures of corundum, mullite and calcite. To get diffraction patterns of the mixtures, two different diffractometers are used and their outputs are then compared.
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Nonconventional synthesis of high entropy carbides
Šolcová, Pavlína ; Tyrpekl, Václav (advisor) ; Havlíček, David (referee)
This thesis aimed to streamline the method of the preparation of high entropy carbides. The simplification of synthesis and expends reduction were achieved using sol-gel method instead of using commercial starting powders. As precursors of transition metals, the chlorides (TiCl3, TaCl4, HfCl4 a NbCl5) and chlor-oxide (ZrOCl2) were used. The source of carbon was citric acid. All reactants were mixed in solution and dried to gel. The pyrolysis at 800 řC afterwards leads to creation of the amorphous carbon, which embedded the transition metal oxide nanoparticles. The carbothermal synthesis was completed in Spark plasma sintering device at 1400 řC, 1600 řřC and 1900 řC. Formation of high entropy carbide phase was achieved at 1600řC, which is almost 400 řC less than previously reported in literature. Intermediate and final products were characterized with powder X-Ray diffraction, scanning electron microscopy and products, in addition, were characterized with transmission electron microscopy and elements mapping. Key words: high entropy carbides, carbothermal reduction, high temperature ceramics, sol-gel method,
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Triazacyclononane derivatives bearing thiazole side group for anchoring to polymeric materials
Willimetz, Robert ; Kotek, Jan (advisor) ; Havlíček, David (referee)
With the growing resistance of bacteria to antibiotics, it is crucial to search for other ways to treat and prevent bacterial infections. Bacteria attached to the surface of medical implants can form a so-called biofilm, which is able to potentially cause the infection and subsequent health issues. The aim of this thesis was to prepare ligand capable of complexation of hydrolytically active metal ions, which would be able to cleave nucleic acids of bacteria. The selected ligand was 1,4,7-triazacyclononane derivative linked to thiazole side group for anchoring to polymeric materials. With these antibacterial polymeric substances it would be possible to coat the surfaces of the implants and therefore prevent developing of infections.
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Didactic software for chemistry education at the ISCED 2 level
Sadykov, Timur ; Čtrnáctová, Hana (advisor) ; Havlíček, David (referee) ; Svoboda, Lubomír (referee)
1 ABSTRACT The current chemistry education solves problems related primarily to the setting of the curriculum contents, which would be professionally correct, appropriately extensive, and at the same time connected with current aspects of life in modern society, and to problems of teaching strategies that would stimulate the students into an interest in science and commitment to it. The main goal of this dissertation is to create an educational website with an interactive chemistry course for lower secondary schools (ISCED 2) and verify its effectiveness in school practice. The first part of the dissertation describes methods of interactive chemistry teaching supporting the increase of the students' cognitive activity and the effectiveness of the learning process using ICT. The second part characterizes the chemistry course thus created and lists various ways to apply interactive teaching in it. Our interactive course contains a total of 14 thematic units, each with 2-6 subthemes. All themes are processed with respect to the practical application of the subject matter using the listed interactive education methods. This course was tested in 2018-2020 during chemistry lessons in Kazakhstan and Czech Republic, and the students' opinions toward interactive teaching in this study were tested using a simple...
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Study of proton conductivity on powder samples
Nižňanský, Matěj ; Havlíček, David (advisor) ; Kubíček, Vojtěch (referee)
The focus of this thesis is the synthesis and characterisation of one newly prepared and one previously prepared compound which based on the results of x-ray structure analysis both contain systems of conveniently long hydrogen bonds. These systems potentially allow proton transfer through their structure. The results acquired by measuring proton conductivity of the newly prepared substance are also discussed in this thesis. Furthermore, it contains the results of the characterisation of both prepared substances by IR spectroscopy, powder x-ray diffraction and diffraction on monocrystal. The measurement of proton conductivity was carried out using tablets consisting of pressed powder samples which had gold-palladium alloy electrodes applied to them. The specific conductivity of these samples was determined by the measured electric resistance and the size of these tablets. Based on the conducted measurements, it can be stated that the newly synthesised substance does not exercise proton conductivity within the detection limit of used hardware, whereas the previously prepared one does. These results are further discussed in corresponding chapter considering primarily the structure of both substances.
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