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Advanced Magnesium Alloys Surface Modification by Ni-P Based Coatings
Kosár, Petr ; Pacal, Bohumil (referee) ; Nový,, František (referee) ; Havlica, Jaromír (advisor)
The dissertation thesis deals with the modification of the surface of advanced magnesium alloys with Ni-P based coatings. At the beginning of the theoretical part, the structures of the used magnesium alloys and the influence of individual alloying elements on their properties are characterized. In the following part of the thesis the current knowledge in the field of electroless deposition on metal substrates is summarized. The theoretical part of the thesis is closed with contemporary research study in the field of clarification and determination of possible mechanism of electroless deposition. For the subsequent investigation of the mechanism of electroless deposition on magnesium alloys, it was necessary to characterize the microstructure and composition of individual magnesium alloys in the first phase of the experimental part. The exact composition of elements was determined using glow discharge optical emission spectroscopy and scanning electron microscopy with EDS was used for composition of phases of magnesium alloys. Using scanning electron microscopy and detailed elemental analysis of the coated magnesium substrate, it was found that for optimal Ni-P coating deposition on magnesium alloys, acid pickling prior coating is required in a mixture of acetic acid and sodium nitrate. Using the XPS method, it was found that the phosphorus atom in the sodium dihydride-diphosphate reducing agent has a + V charge. 4 At the end of the experimental part scanning electron microscopy and detailed elemental analyses were used for monitoring of the Ni-P particles nucleation and growth in the first 120 seconds of the coating process.
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Preparation and characterization of silicon-based materials
Šlechta, Miroslav ; Dian, Juraj (advisor) ; Jelínek, Ivan (referee)
Title: Preparation and characterization of silicon-based materials Author: Miroslav Šlechta Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. Juraj Dian, Csc., Department of Chemical Physics and Optics Abstract: Porous silicon is nanostructured material based on silicon. He was prepared by anodic etching of crystalline silicon in hydrofluoric acid. Physical and chemical properties of porous silicon nanocrystals resulting from the dimensions, which range from units to tens of nanometers. For nanostructured silicon compared to crystalline silicon, exhibit unique properties that depend on the degree of quantum dimensional phenomena and phenomena on its large internal surface. Suitable choice of the silicon substrate, particularly in terms of conductivity and crystallographic orientation, and technological conditions (in particular electrolyte composition, the etching time and current density) can be prepared nanostructured materials of different pore sizes - macroporous, mesoporous and microporous silicon and varying representation Si-O and Si-H bonds. Morphology and chemical composition of the surface of porous silicon allows to think of it as a suitable material for a range of applications - particularly chemical sensors and biosensors, optoelectronics and biomedical applications....
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Investigation of defects in thin metallic films
Hruška, Petr ; Čížek, Jakub (advisor)
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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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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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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Growth of 3D Structures Induced by Electron Beam on Ceramic Substrates
Bukvišová, Kristýna ; Čechal, Jan (referee) ; Salamon, David (advisor)
Vystaví-li se vzorek působení elektronového svazku, dojde na jeho povrchu ke strukturním změnám. Jednou z těchto změn je vertikální růst 3D struktur na keramických materiálech. V práci jsou zkoumány podmínky nutné pro takový proces. Nárůst teploty často zapříčiní povrchové změny, proto je v práci proveden výpočet ohřevu materiálu elektronovým svazkem. Dále je zkoumán vliv různých parametrů svazku na růst 3D struktur, závislost objemu a rozměrů je analyzována pomocí AFM. Výsledný odhad nárůstu teploty se pohybuje v řádech jednotek, maximálně desítek K. Výrazný objemový růst je pozorován pro nízká urychlovací napětí a malé proudy. Výška vzniklých struktur dosahuje 100 nm za minutu a je nepřímo úměrná velikosti proudu.
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Mycobacterium smegmatis biofilm formation om glass and zirkonia beads-proteomic study
Sitařová, Barbora ; Weiser, Jaroslav (advisor) ; Zikánová, Blanka (referee)
Biofilms represent universal strategy for bacterial survival. Living in form of biofilms, bacteria acquire wide range of advantages over planktonically growing cultures. It can be assumed that nearly 99% of world bacterial population is living in form of biofilms. There are benefits and drawbacks associated with bacterial biofilms for mankind. Life in biofilms makes pathogens more effective and persistent through higher antibiotic resistance and helps them to hide before immune system of the host. Mycobacteria, which are capable of forming biofilms on variety of surfaces, differ from most of other bacteria by unique composition of their cell wall. It provides them with high resistance against physical or chemical damage. This is one of the reasons for considering Mycobacterium tuberculosis as a highly potent pathogen. The studies of mycobacterial biofilms are motivated by effort to improve or find new therapeutic methods. This work is aimed at morphological and proteomic comparative analyses of biofilms obtained from Mycobacterium smegmatis grown on surface of glass and silica/zirconium beads, on liquid medium surface or grown submerged in shaken planktonic culture. We have developed technique for preparation of "floating" biofilm sample to be observed in SEM. We have shown that the growth of...
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Monitoring of Mycobacterium smegmatis floating biofilm development - morphological and proteome analysis
Sochorová, Zuzana ; Weiser, Jaroslav (advisor) ; Zikánová, Blanka (referee)
Microorganisms grow in planktonic form, but more often they adhere to a number of surfaces and create three-dimensional structures called biofilms. Floating biofilms, which are formed at the water-air interface, are one of the life strategies, which the bacteria can take. Non-pathogenic Mycobacterium smegmatis was used as a laboratory model for the study of this kind of biofilm. The understanding of mechanisms of their formation of this species may be applicable to the pathogenic species of the genus Mycobacterium, study of which in the laboratory brings a number of disadvantages. This diploma thesis focuses on the morphological and proteome analysis of the M. smegmatis floating biofilm. Using a stereo microscope and scanning electron microscopy was observed that bacteria clump and create the "nucleation centres" at the beginning of the biofilm development. This centers grow to the surroundings and connect afterwards. In the later stages of the development the centers fuse in compact layer, which then grows into the compact and multilayer biofilm. The key method in this study was two-dimensional electrophoresis of proteins. The proteome analysis of floating biofilm was performed with this method. The preparation of protein samples and the method for protein concentration measurement was optimized....
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Růst Mycobacterium smegmatis na agarovém médiu a agarovém médiu pokrytém celofánovou folií - morfologická a proteomová studie
Ramaniuk, Volha ; Weiser, Jaroslav (advisor) ; Beranová, Jana (referee)
Biofilm formation is one of the most common bacterial survival strategies. Majority of bacterial species are able to form these three-dimensional structures, including pathogens like Mycobacterium tuberculosis. Representatives of Mycobacterium genus widely occur in the nature, although they can cause serious problems when they appear in medical equipment and artificial replacements of the human body. Non-pathogenic Mycobacterium smegmatis mc2 155 was used as a model organism in our experiments. We investigated morphology of the three- and six-day-old colonies (in fact biofilms) on agar and agar covered with cellophane using Stereo microscope and Scanning Electron Microscope. We found that a type of surface as well as a carbon source has a great influence on the morphology of the M. smegmatis colonies. We isolated proteomes from the agar and cellophane cultures and from planktonic culture. Two-dimensional electrophoresis was used as the main proteomic method. Proteomic data were analyzed using PDQuest software. Then the sets of proteins detected by qualitative and quantitative analyses were compared using Venn diagrams. As a result, we recognized 7 unique proteins that might be specific for recognition and adhesion of bacteria to the cellophane, no unique protein in agar proteome and 46 unique...
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The Rheological Behavior of Polymer Solutions Suitable for Electrospinning
Divínová, Nikol ; Voráč,, Zbyněk (referee) ; Chamradová, Ivana (advisor)
This diploma thesis deals with preparation and characterization of aqueous solutions of polyvinyl alcohol suitable for electrospinning. In the theoretical part method of electrospinning is described, including parameters which influence this process. Literary research also includes a chapter about rheology, which deals with the rheological properties of polymers, specifically PVA. The experimental part describes the preparation and rheological study of of aqueous solutions of polyvinyl alcohol, which were then spun. The morphology of prepared nanofibers was studied by using scanning electron microscopy (SEM). The effect of molecular weight, the solvent, concentration of solution, rheological properties, electrical conductivity and surface tension on the spinability, diameter and morphology of nanofibers is discussed.
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