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Toxicity study of antimicrobial wound dressings and perspective novel nanomaterials
Kozlíčková, Hana ; Vojtová, Lucy (referee) ; Zajíčková, Lenka (advisor)
This bachelor thesis deals with the study of toxicity of selected commercial antimicrobial wound dressings (StopBac STERILE, containing silver ions and Traumacel Biodress Disinfect, containing chlorhexidine) and antimicrobial nanomaterial, provided by CEITEC BUT laboratories. The experimental part of the work describes the preparation of this polycaprolactone nanomaterial, on which a layer of copper was subsequently deposited by the magnetron sputtering system BESTEC (MAGNETRON). Furthermore, a method was designed to study the cytotoxicity of individual shelters with antimicrobial additives. These tests were performed in vitro on cell cultures by leaching the materials in the laboratories of the Faculty of Science, Masaryk University in Brno. We found that, with the exception of chlorhexidine, low concentrations of active substances extracted from the materials promoted the proliferation of the studied cells, while at high concentrations there were also cytotoxic effects. The analysis of individual materials was also performed using scanning electron microscopy and energy dispersive X-ray spectroscopy.
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Toxicity study of antimicrobial wound dressings and perspective novel nanomaterials
Kozlíčková, Hana ; Vojtová, Lucy (referee) ; Zajíčková, Lenka (advisor)
This bachelor thesis deals with the study of toxicity of selected commercial antimicrobial wound dressings (StopBac STERILE, containing silver ions and Traumacel Biodress Disinfect, containing chlorhexidine) and antimicrobial nanomaterial, provided by CEITEC BUT laboratories. The experimental part of the work describes the preparation of this polycaprolactone nanomaterial, on which a layer of copper was subsequently deposited by the magnetron sputtering system BESTEC (MAGNETRON). Furthermore, a method was designed to study the cytotoxicity of individual shelters with antimicrobial additives. These tests were performed in vitro on cell cultures by leaching the materials in the laboratories of the Faculty of Science, Masaryk University in Brno. We found that, with the exception of chlorhexidine, low concentrations of active substances extracted from the materials promoted the proliferation of the studied cells, while at high concentrations there were also cytotoxic effects. The analysis of individual materials was also performed using scanning electron microscopy and energy dispersive X-ray spectroscopy.
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The content and binding of silver in galena
Němec, Matěj ; Goliáš, Viktor (advisor) ; Zachariáš, Jiří (referee)
Galena as the most important silverbearing ore is found in almost every Ag deposit. If the content of Ag is higher than 0,5 wt. % then is called galena solid solution - PbSss. The galena Ag has two forms of occurrence - inclusions and isomorphic silver. Aboat ninety percent of galena Ag is product of retrograde proces of PbSss cooling. These are matildite (AgBiS2), miargyrite (AgSbS2), diaforite (PbAg3Sb3S8), freislebenite (AgPbSbS3), pyrargyrite (Ag3SbS3) aramayoite (Ag(Sb,Bi)S2), freibergite (Ag12Sb4S13), gustavite (AgPbBi3S6) etc. The smaller amounth of isomorphic Ag is substituted as 2Ag+ = PbII+ . Under the usual conditions of deposition (200 - 300řC) , the solubility of Ag2S is to low. The content of Ag in galena under these conditions is not higher then 0,4 mol. % at 615řC. Most of the isomorphic Ag is bound in coupled substitution Ag+ + Bi III+ /Sb III+ = 2 PbII+ . In this case the content of Ag in PbS can be as high as 9 wt. % at 350 - 400řC. At the deposites where wasn't activated this Bi/Sb - Pb coupled substitution the content of Ag in galena is very low. The content of trace elements of Ag, Bi and Sb can also influence the galena crystal habit. Galena rich on Bi ususaly creates octahedral crystals. Galena with a higher content of Ag and Sb usualy creates cubic crystals.
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Effect of silver in homogeneous gold catalysis
Motloch, Petr ; Roithová, Jana (advisor) ; Hocek, Michal (referee)
Gold catalysis has recently experienced a sustained upswing in interest from scientific community. The amount of new reactions catalysed by gold is so significant that little is known about mechanisms of most of these reactions. Research into mechanisms of (not only) gold catalysed reactions is therefore very significant area of interest and important to the continued improvement of gold catalysed reactions. Formation of cationic π-complexes is considered a first mechanistic step in reactions catalysed by gold(I). The bond dissociation energies of gas phase cationic π-complexes were investigated by mass spectrometry and theory calculations in this thesis. These complexes consisted of differently substituted unsaturated hydrocarbons (alkenes, alkynes, alkadienes and allenes) and complex cations of silver and gold containing second ligand (triphenylphosphine, acetonitrile). On the basis of the results obtained from this study, a possible origin of the "silver effect" in gold(I) catalysis is discussed. Key words catalysis, gold, silver, mass spectrometry, DFT calculations, reaction intermediates
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Application of non-membrane electrolytic cell for electrochemical volatile species generation of transition metals
Kobrlová, Andrea ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
This diploma thesis is focused on the study of electrochemical generation volatile species of gold and silver. Two non-membrane electrolytic cells were constructed for electrochemical generation volatile species. These cells differ in the volume of electrode chamber. An atomic absorption spectrometry with quartz tube atomizer was used in most experiments. The equipment was performed in flow continuous mode. Experiments confirmed, that it is possible to use an atomic absorption spectrometry with quartz tube atomizer for generate volatile species of gold and silver by using two non-membrane electrolytic cells. The main part of this thesis was to find optimal conditions for the electrochemical generation of volatile species of gold and silver. These optimized parameters were: the cathode material, the type of electrolyte, the flow rate of the carrier gas, the generation current and the electrolyte flow rate. The calibration curves for both analytes were measured for both non-membrane electrolytic cells and the basic characteristics of the measurement were observed. Detection limit for electrochemical generation of gold was 1,61mg dm 3 and repeatability 3,93 %, detection limit for electrochemical generation of silver was 0,20 mg dm 3 and repeatability 7,33 %. Thanks to the experiments with a...
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SIlver binding at the polymetallic deposits of Blanice furrow and comparison with similar deposits in the world
Kuchyňová, Markéta ; Zachariáš, Jiří (advisor) ; Goliáš, Viktor (referee)
Blanice Furrow is about 200 km long fault system which extends from Český Brod to basin of Danube in Austria. Ore mineralization is tied to rupture structure of Blanice Furrow. Predominant polymetallic Ag-Pb-Zn±Cu mineralization occurs along entire length of Blanice Furrow. Other important type of mineralization is gold mineralization (Roudný deposit, Dobrá Voda deposit) and uranium mineralization (Okrouhlá Radouň deposit). Historical medieval silver mining districts are Stříbrná Skalice-Střímělice, Ratibořické Hory-Stará Vožice and Rudolfov. This paper describes geology and mineralogy of silver- deposit in Blanice Furrow and comparisom of Blanice Furrow with different types of hydrothermal Ag- deposits such as Ag-Ni-Co-Bi-As deposit or Mississippi Valley type. In Blanice furrow the silver isn't bound to galena and sphalerite as we would expect, but to Ag-tetrahedrite and other silver-bearing minerals. Silver from tetrahedrite is a product of retrograde exchange reaction, which was in progress during cooling in solid state . Ag-values of tetrahedrite and Ag-Sb-S phases can be used it as mineral thermometer. Mineral thermometer can help us to define temperature durinng formation of mineralization, in case of Blanice Furrow the temperature is defined between 200 and 300 řC. Powered by TCPDF (www.tcpdf.org)
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Czech portrait medal of the past and present
Seidlová, Kristýna ; Vlnas, Vít (advisor) ; Venclík, David (referee)
This diploma thesis deals with Czech portrait medals in the past and present. The aim was to map Czech medal portrait work from its origins in the Renaissance to the present. At the beginning, the work is focused on the precious metals from which the medals are made, gold and silver. The history of gold and silver is included in the theory. The concepts of numismatics or commemorative medals made of gold and silver as investment preservation of real value are clarified. We were interested in the overall artistic process of producing portrait medal into the final product. The historical development of medals in the Czech lands followed. In each period, important artists, medalists, and their work are mentioned. All chapters contain pictorial materials. The practical part is devoted to all existing mintages of Karel Gott, which is a unique medal investment. Along with him, contemporary medal artists are characterized in more detail. In the end, the first findings about the portrait medal are summarized. The work brings an overall view of portrait medal work. Medal making represents a specific area of fine and sculptural art. It is an artistic artifact that reflects our history. KEYWORDS medal, gold, silver, portrait medal, commemorative medal, numismatics, art mintage, collecting
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Mléčné bakterie ve vinařství a studium jejich inhibice
Sapanelová, Claudia
This diploma thesis deals with the issue of lactic acid bacteria in oenology and study of their inhibition. It includes the research of the available resources aimed at this topic, including the recent practical knowledge. It focuses on the general characteristics and taxonomy of lactic acid bacteria, describes the genes present in wine production, their development, metabolism and the associated sensory changes or currently known inhibition methods. The practical focus of the thesis is the study of the possibility of using the antibacterial effects of silver compounds against undesirable lactic acid bacteria in wine technology. Within the research, were established appropriate microbiological experiments and examined the influence of different doses of selected inhibitory agents: silver nitrate, colloidal silver and silver nanoparticles on the development and metabolic activity of bacteria of the species Pediococcus damnosus strain CCM 2465. The experiment proved certain inhibitory effects of all the compounds, whereas better results were achieved with silver nitrate and colloidal silver.
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Generation of metallic nanoparticles by non-thermal plasma in liquids
Čechová, Ludmila ; Blahová, Lucie (referee) ; Kozáková, Zdenka (advisor)
This thesis focuses on the process of nanoparticle generation using new source of nonthermal plasma combining corona and pin-hole discharge in liquids. The theoretical part is focused on generation of metallic nanoparticles using various types of plasma discharge, the properties of metallic nanoparticles, their preparation by other methods and methods of characterization of nanoparticles. The experimental part deals with the preparation of copper, silver and gold nanoparticles from solutions of their precursors. The influence of experimental conditions, such as the influence of voltage polarity, effect of precursor concentration, effect of added electrolyte or reducing agent were investigated. All samples were analyzed by UV-VIS spectroscopy. Dynamic light scattering was used to determine the sice of nanoparticles. To confirm the presence of nanoparticles, samples were analyzed using scanning microscope with and energy dispersion spectrometer for elemental analysis.
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