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Micronization of biopolymer material
Gistingerová, Radka ; Wikarská, Monika (referee) ; Pospíšilová, Aneta (advisor)
This bachelor thesis focuses on the preparation of poly(3-hydroxybutyrate) microparticles for cosmetic products. The particles were prepared by emulsion technology, where a chloroform solution of poly(3-hydroxybutyrate) was dispersed in an aqueous solution of polyvinyl alcohol. The original poly(3-hydroxybutyrate) was also in powder form, but it was thought that its properties could be improved by this treatment. Evaporation of all the chloroform produced poly(3-hydroxybutyrate) particles. By changing the input concentrations of the two components, the particle size distribution was altered. All prepared powders were measured using a scanning electron microscope and measured by laser diffraction. Experiments and subsequent measurements showed that increasing the concentration of the emulsifier solution leads to an overall decrease in particle size, whereas a higher concentration of poly(3-hydroxybutyrate) causes an increase in particle size. To evaluate the potential of the prepared particles in cosmetics, all powders were evaluated sensorially. The evaluators observed almost no differences between the powders, only the original poly(3-hydroxybutyrate) powder was rated slightly worse compared to our prepared powders. The powder that is currently used in cosmetic products was rated very similarly to the powders that were prepared by emulsion technology.
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Preparation and characterization of nanostructured III-V semiconductor materials
Maniš, Jaroslav ; Kostelník,, Petr (referee) ; Hospodková,, Alice (referee) ; Šikola, Tomáš (advisor)
Předkládaná dizertační práce se zabývá výrobou a analýzou gallium nitridových (GaN) nanostruktur ve třech odlišných formách. V prvním případě byl zkoumám trojdimenzionální GaN ve formě nanokrystalů rostených na grafenu. Nanokrystaly byly připraveny s využitím techniky droplet epitaxy, která mimo jiné umožňuje růst nanostruktur za nízké teploty substrátu (T = 200°C). Studium se zaměřovalo jak na charakterizaci kvality připravených nanokrystalů, tak na statistický popis růstu. V dalším kroku byly připravené struktury využity pro výrobu fotodektoru citlivého na ultrafialové světlo. Výroba fotodektoru a jeho úspěšné použití slouží jako základ pro navazující výzkum. Ve druhém případě byly studovány dvoudimenzionální GaN nanostruktury, které byly rovněž připraveny za nízké teploty křemíkového substrátu. Následná analýza se soustředila na popis krystalové struktury a prvkovou analýzu, neboť byly takovéto struktury pozorovány vůbec poprvé. Další rozvoj možností přípravy těchto nanostruktur je předmětem navazujícího výzkumu. Ve třetím případě byly zkoumány jednodimenzionální GaN nanodráty připravené na safírovém substrátu. Účelem tohoto projektu bylo získání datasetu pro ověření teoretického modelu, který popisuje růst horizontálních nanodrátů. Na základě sběru a analýzy dat se podařilo modelovat růstovou dynamiku GaN nanodrátů, která byly v souladu s teoretickým modelem.
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Program-controlled freeze drying for the preparation of the drug-delivery system based on polysaccharide and hydrophobic molecules
Dufková, Michaela ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
The lyophilization process favors the hydrophobic effect between the individual dextran chains. This hydrophobic effect allows hydrophobic drugs to settle and remain within the biopolymer. Due to hydrophobic effect, dextran can serve as a carrier for the distribution of hydrophobic drugs. The goal of this thesis was to prepare a carrier system based on native dextran using program-controlled freeze-drying. Hydrophobic drugs were modeled using the fluorescent probes pyrene and prodane. The effectiveness of promoting the hydrophobic effect was studied using infrared spectrometry, fluorescence spectrometry and scanning electron microscopy. Using ATR-FTIR spectrometry, a shift of the absorption band of thevalence vibration of the C–O bond in OH groups in alcohol was observed. Using fluorescence spectrometry, the emission polarity index was calculated for pyrene from the 1st and 3rd maximum fluorescence intensity, and for prodan, a shift of the maximum fluorescence intensity to lower wavelengths was observed. SEM images showed that during the lyophilization process, the dextran structure formed a dense network of fibers, indicating the presence of many sites with a higher content of hydrophobic domains. Positive results were obtained with these methods, which proved the positive effect of lyophilization on the formation of a hydrophobic effect between individual polysaccharide chains. The results may contribute to the development of carrier systems for hydrophobic drugs.
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Influencing the hydration of high-performance composites using zinc ions
Všetečka, Tomáš ; Hajzler, Jan (referee) ; Novotný, Radoslav (advisor)
The bachelor thesis is focused on the influence of hydration of high-performance cementitious composites, more specifically reactive powder composites. Zinc ions were supplied by the compounds of zinc oxide and zinc sulphate heptahydrate. Zinc ions were added by weight content to cement at concentrations of 0.2; 0.5 and 1.0 wt. %. The development of properties depending on the content of zinc ions and the type of compound used was monitored in this work. The measured values were compared with reference values that did not contain zinc ions. The highest compressive strengths were obtained with a sample containing 1.0% Zn in the form of zinc oxide. However, this sample is associated with a longer setting time due to the retarding effect of zinc ions on hydration. The retardation effect was monitored using isothermal calorimetry. For samples containing zinc ions, a negative effect on the brass layer of steel fibers, which was used as reinforcement, was observed. Due to the addition of zinc ions, dezincification and subsequent removal of brass from the surface of the fibers took place. Therefore, these specimens had lower tensile strengths. A positive effect on the differential ballistic protection efficiency factor was observed for a sample containing 1% Zn in the form of zinc oxide.
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Internet Educational Atlas Focusing on Soil Arthropods
Dvořáková, Jana ; Mourek, Jan (advisor) ; Říhová, Dagmar (referee)
The main objective of this thesis was to create an educational website aimed at soil arthropods. It can be used primarily by teachers of biology and ecology, lecturers of extracurricular science education or by the students who are interested in this issue. This photographic atlas of soil arthropods consists of my own micro images obtained by the use of light and scanning electron microscope. The micro images are accompanied by text to each group of soil arthropods, which is divided into sections containing information about the systematic classification, anatomy and morphology, biology and importance, eventually representatives of the group. The atlas is accompanied by other materials usable in the classroom, such as didactic test, didactic game and proposals for group work, worksheet, field and laboratory work or educational presentations focused on soil arthropods. These materials can be downloaded from the website, along with the entire atlas of soil arthropods. The atlas is available on the following address: https://sites.google.com/site/pudniclenovci/. The review of the literature deals with the importance of arthropods in the soil and their mutual interactions. Then I describe the methods of study of arthropods (sampling, sample preparation for light and scanning electron microscopy and...
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Transmission Electron Microscopy of Al-Mg Aluminium Alloys with Addition of Sc and Zr
Křivská, Barbora ; Šlapáková, Michaela (advisor) ; Málek, Přemysl (referee)
Abstract. The microstructure and its evolution during isochronal annealing of a twin roll cast Al-3.2Mg-0.19Sc-0.14Zr (wt.%) alloy was investigated by light optical microscopy and electron microscopy. Two procedures - equal channel an- gular pressing and annealing at 300 řC for 8 h were applied to enhance mechanical properties of the alloy. The annealing led to the precipitation of a fine dispersion of Al3(Sc,Zr) particles providing an increase of ∼20 HV in the Vickers microhard- ness. Equal channel angular pressing refined significantly the microstructure and raised the microhardness by about 30 HV. Applying of the 300 řC / 8 h both before and after equal channel angular pressing did not induce further strength- ening. However, the precipitation of the Al3(Sc,Zr) phase had a stabilizing effect when the material was exposed to the subsequent isochronal annealing. 1
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Studium defektů v tenkých kovových vrstvách
Hruška, Petr ; Čížek, Jakub (advisor) ; Bulíř, Jiří (referee)
In the present work Mg films prepared by RF magnetron sputtering were studied. Variable energy positron annihilation spectroscopy (VEPAS) was employed for investigation of defects in the Mg films. VEPAS characterization was combined with scanning electron microscopy and X-ray diffraction in order to determine grain size, phase composition and texture. The effect of different deposition rate and deposition temperature, annealing, various substrates and film thickness on the structure and amount of defects present in the Mg films was examined. Defect studies by VEPAS showed that positrons in studied Mg films are trapped at misfit dislocations and at vacancy-like defects in grain boundaries and their density can be reduced by the deposition at elevated temperature. 1
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Effect of substantial grain refinement on microstructure and mechanical properties of precipitation hardenable magnesium alloys.
Hofman, Daniel ; Minárik, Peter (advisor) ; Janeček, Miloš (referee)
Properties of magnesium alloy WE43 and the effect of substantial grain refinement by ECAP were studied. The compressive strength test revealed a significant increase of yield strength after ECAP, resulting in yield strength of over 400 MPa after 8 ECAP passes. The material remained surprisingly ductile in both compression and tension. Thermal stability of the material was investigated via Vickers hardness test. The ultrafine-grained structure shows good thermal stability up to 300 řC, where the precipitates start to dissolve and grain size starts to increase, resulting in sharp fall of hardness. Annealing of the initial state showed best results for 210 řC where the precipitation hardening led to an increase in hardness up to ∼101 HV.
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Utilization of biosurfactants for incorporation of hydrophobic domains into modern controlled-release systems
Nešpor, Tomáš ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This work deals with the current topic of carrier systems. Since the biggest problem is the passage of hydrophobic drugs through the bloodstream, or through universal body barriers (eg blood-brain), it is necessary to chemically modify these carriers in order to be able to administer hydrophobic substances effectively. Based on a literature search, several systems are designed and subsequently studied, in which there is a presumption of possible use for carrier systems and at the same time they have biosurfactants incorporated in them due to their ability to solubilize hydrophobic molecules. The theoretical part of this work will describe the individual biosurfactants, the process of their production, their physicochemical properties, and the possibility of their use in carrier systems. At the same time, the individual carrier systems, the procedure of their preparation, the possibilities of their use are described, and their advantages and disadvantages are also compared. In the practical part, the screening of both individual substances and their mutual interactions, as well as methods used to study the emerging structures is then performed. The study of molecular interactions is primarily performed using the technique of dynamic light scattering. The next part describes the optimization of hydrogel formation with incorporated biosurfactants in their structure and then the formed gels are subjected to rheological and solubilization tests. The study of the internal structure of these gels is performed using a scanning electron microscope.
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Welding of heterogeneous joints by laser
Charvátová, Eliška ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
This diploma thesis deals with welding of two dissimilar materials by laser. The samples were welded by direct beam guidance and wobbling, with and without using high alloy filler material and with the use of a diffusion barrier in the form of nickel. Welding was done with different shielding atmospheres. Nondestructive (VT, PT, UT-PA, RT) and destructive tests were performer (tensile test at room and elevated temperatures, microhrardness). Metalography was suplemented by EDX analysis of selected elements.
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