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Influence of antibacterial nanomaterials on the development of bacterial resistance
Bábíková, Daniela ; Lucie,, Bozděchová (referee) ; Šmerková, Kristýna (advisor)
Bacterial resistance to antibiotics is a long-discussed problem. The use of antibiotics in primary agricultural production, especially in pig breeding. High levels of zinc subsequently seeps into the soil in the form of secondary agricultural products. Doses of effect the intestinal bacteria of pigs, but also the microorganisms in the environment which can subsequently lead to the development of resistance to metals also antibiotics. This thesis deals with the effect of ZnO and newly used nanoparticles (ZnO NPs) on bacteria S. aureus, methicilin-rezistant S. aureus and E. coli. Acquired data point to the effect of ZnO on minimal inhibition concentration of antibiotics and the development of resistance in E. coli. Based on biochemical tests, the change of metabolic pathways reacting with selected substrates was confirmed. Repeated subcultur of bacteria with tested ZnO and ZnO NPs has on the susceptibility of bacteria to antibiotics and changes their biochemical pathways. Studies dealing with the issue of long-term effect on medicinal substances are essential for the development of modern antibacterial components.
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Comparison of microbial interactions of zinc oxide nanomaterials in various size and shape
Rutherford, D. ; Jíra, J. ; Mičová, J. ; Remeš, Zdeněk ; Hsu, H.S. ; Rezek, B.
Zinc oxide nanoparticles (ZnO NP) have shown great potential as a novel antibacterial material at a time when resistance towards conventional antibiotics is becoming more prevalent. We report bacteria inactivation by ZnO NP with novel hedgehog-like morphology using model gram-negative (E. coli) and gram-positive (S. aureus) bacteria. E. coli exposed to the novel ZnO hedgehog NP during growth resulted in 4 orders of magnitude reduction in viable cell concentration after 24 h, which is more than 2 orders higher reduction compared to commercially available ZnO NPs with nominal sizes from 50 nm to 20 um. There was a positive correlation between hedgehog NP concentration and bacteria cell concentration reduction within the range tested 0.1 – 1.0 mg/mL. S. aureus was less sensitive to ZnO NP exposure and inactivation effect of various ZnO NP, was comparable. The effect can be thus attributed to direct mechanical damage of the bacterial mebrane that is the most effective for the novel hedgehog ZnO NP. This conclusion was corroborated also by disk diffusion assays.\n
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Preparation of nanowires for photonics
Mikula, Martin ; Grym, Jan (referee) ; Kolíbal, Miroslav (advisor)
This thesis is dealing with nanowires of zinc oxide and of cesium lead bromide. Main goal was a preparation of ZnO nanowires using MBE. This goal was partially achieved and growth of needle-like structures was observed. Another goal was characterization of already prepared ZnO nanowires. We successfully determined polarity of their surfaces, examined the influence of lattice defects and assessed the result of their doping. Side goal of this work was characterization of nanostructures of cesium lead bromide. However, preparation of cesium lead bromide nanowires remains an open issue.
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Growth of highly doped ZnO nanowires
Andrýsek, Michal ; Macák, Jan (referee) ; Kolíbal, Miroslav (advisor)
This diploma thesis is about ZnO nanowires growth, their doping and analysis. High temperature and pressure oxidation of brass foil and deposition from effusion cell in oxidative atmosphere utilized for nanowires growth. The growth is affected by different temperature and pressure. It has been shown that under certain experimental conditions nanowires can be prepared by the former method. However, the growth was hindered when effusion cell was used.
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Microstructural Study and Analysis of Hard Zinc
Luptáková, Natália ; Pešlová, F. ; Stodola, P. ; Stodola, J.
The presented work is focused on the character and morphology of the input material for the production of metallic zinc which is used in the production of ZnO through indirect pyrometallurgical processes. The input material is the key parameter in the production of high-quality zinc oxide. For the prediction of a complex production process when problematic situation may occur, the systematic analysis of the input zinc raw materials is needed. Undesirable phases in the feedstock can be identified through profound recognition of the source material and the nature of its microstructure. Chemical composition of zinc metal and zinc additives helps to detect the phases occurring in the matrix. Undesirable phases in the feedstock can form hard and brittle compounds. If these compounds diffuse into the lining during thermal processes, they become the cause of stress in metallurgical ceramics. From the microstructure viewpoint, the heterogeneity of the grain size, various morphology of intermediate phases, their layout, arrangement, etc. can be expected. The results obtained by analysis are used to minimize waste-zinc slag and to eliminate the conditions which enable the formation of the undesired product, thereby increasing the productivity of the zinc oxide production. Moreover, another important knowledge could be used for modernization and effective the process of industrial production of ZnO in practical application in military technologies.
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The Study of ZnO Crystal Growth in Supersaturated Alkaline Solution
Bannert, Tomáš ; Máca, Josef (referee) ; Chladil, Ladislav (advisor)
This thesis deals with the study of growth of zinc oxide crystals from supersaturated solutions using a scanning electron microscope and XRD methods. The work is divided into a theoretical and an experimental part. The theoretical part analyses issues related to the principle of operation of electrochemical cells with an emphasis on Ni-Zn batteries and phenomena limiting the life and efficiency of Ni-Zn batteries with a focus on phenomena that affect precipitation processes of zinc oxide crystals. It also analyses and compares the appropriateness of the methods that have been used to study the growth of the prepared zinc oxide crystals. The experimental part describes the preparation of a supersaturated solution, the process of each analysis and its evaluation. The results of each method are compared with the theoretical assumptions and among themselves. The experimental part also contains a chapter dealing with the design of in situ X-ray diffraction analysis methods of the obtained zinc oxide crystals.
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Growth of ZnO nanowires
Mikula, Martin ; Voborný, Stanislav (referee) ; Kolíbal, Miroslav (advisor)
In this thesis the most important properties of nanowires are briefly characterized and possible methods of their synthesis are described. Special attention is paid to zinc oxide nanostructures as well as VLS mechanism, which is crucial for explanation of nanowire growth. Furthermore, deposition chamber for growth of ZnO nanowires has been assembled and effusion cell for zinc has been tested. Testing of the cell revealed one major drawback of its design, which prevents its use for zinc deposition. Therefore, no growth of ZnO nanowires has been carried out and before it can be accomplished, the effusion cell has to be modified.
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Semiconductive gas sensors for detection of organic gases and vapours
Šedivý, Matúš ; Gablech, Evelína (referee) ; Gablech, Imrich (advisor)
This bachelor thesis is focused on gas sensors. Basic characteristics of sensors are discussed in the first part. Next part contains an overview of the most used types of gas sensors based on different physical principles. The main aim of thesis outlines last chapter where process of making gas sensors with different semiconductive metal oxides active layers is described. This thesis also describes measuring of their characteristics and characteristics of commercial gas sensor TGS 822 made by Figaro. Measured data are processed in graphs and tables and then were used for comparison with created sensors. In conclusion, there are discussed possibilities of improving selectivity of gas detection by using sensors with different active layer.
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The influence of zinc oxide on the cement composite with silica fume.
Dobiáš, Jiří ; Koutný, Ondřej (referee) ; Šiler, Pavel (advisor)
The aim of this work was to investigate the influence of zinc oxide on the properties of blended Portland cement mixed with silica fume. On the pastes were monitored flow properties and by using of isoperibolic calorimetry process of the hydration. On the prepared samples were studied mechanical properties of obtaining values of compressive and flexural strength after 1, 7 and 28 days. By using of XRD were measured phase composition and microstructure development war observed by SEM. The elemental composition of cement leaches was measured by using of ICP-OES.
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Zinc and its compounds
Štefka, Michal ; Kábelová, Božena (referee) ; Pilátová, Ivana (advisor)
The aim of the degree work is the preparation of three consecutive zinc compounds. The theoretical part of the work deals with the most common physical properties of some inorganic compounds of this element. These are especially those compounds that are prepared as intermediates or products in accordance with the instructions set out in the Annex to this degree work. In the experimental part is on the basis of that training described the actual behavior of zinc compared to that provided by general behavior contained in the books and there are presented procedures best saited to the conditions of preparation of individua compounds.
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