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Design and adaptation of electron microscope accessories for in-situ experiments
Drozd, Michal ; Mikulík, Petr (referee) ; Kolíbal, Miroslav (advisor)
Účinnost katalyzátoru v kombinaci s optimalizovanou reakcí a minimalizováním jeho množsví jsou klíčovými faktory při snižování investičních a provozních nákladů v rámci chemických procesů. Díky pokročilým experimentálním technikám mohou být katalyzátory dále zlepšovány. Jednou z těchto technik je in-situ elektronová mikroskopie. Tato práce se zabývá vývojem zařízení pro automatický ohřev vzorku, automatickým vpouštěním reaktantů a měřením parciálních tlaků v komoře mikroskopu. Dále je pomocí provedených experimentů srovnán přístup pomocí environmentálního rastrovacího mikroskopu, kde se využívá laserový ohřev vzorku s přístupem, který využívá skenovací elektronový mikroskop připojený k ultra vakuové komoře, kde se vzorek zahřívá pomocí průchodu elektrického proudu.
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Classification of microstructure of nickel-base superalloys with image analysis using
Volf, Milan ; Čelko, Ladislav (referee) ; Němec, Karel (advisor)
During operational conditions of internal combustion turbines of turbojet engines, the impeller are stressed by load cycles which vary in time, temperature and stress. In the course of operation, the blades are exposed to a considerable number of degradation effects, particularly high-temperature corrosion, fatigue processes and creep. The presented work is aimed at the study of the structure cast nickel-base superalloy INCONEL 713 LC, creep tests exposured. The structural changes (degradation) was clasification by the help of image analyses. Operational conditions of heat parts, used in gas turbines and turbo-compressors, were simulated by creep tests of Inconel 713 LC nickel superalloy during a constant load of temperatures ranging from 750 up to 950°C. Changes in the structure dependent upon time, temperature and stress applied were analysed by means of light and electron microscopy methods and image analyses after the fracture of test bars.
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Specifications of the Ansys Fluent Solution Solver for low pressures in EREM
Šimík, Marcel ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
This thesis is focused on electron microscopy which issue is discussed at the beginning of work. The main attention is dedicated to the Environmental electron microscope, especially the differentially pumped chamber, which the thesis deals with. There is a production of an experimental chamber for analysis of shock waves on going therefore main goal of this thesis was to analyze the flow pattern in this chamber. Using the Ansys Fluent program, simulations of the characteristic flow that arises from the pumping of the vacuum chambers namely the ultrasonic flow at low pressures on which the most suitable turbulent module was applied as well as the degree of discretization was performed. The final analysis of this flow pattern is primarily focused on the localization of the shock wave which experimental evidence is to be lodged by shadow optical method as a part of the new concept of the chamber. The basis for the simulation of the chamber was taken over by Dr. Danilatos, with which the results were compared.
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Concept and Development of Single-purpose Scanning Electron Microscope
Foret, Zdeněk ; Vašina, Radovan (referee) ; Starý,, Vladimír (referee) ; Svoboda, Milan (referee) ; Švejcar, Jiří (advisor)
Electron microscopy has become an essential component in many scientific fields, in which it contributes to new discoveries. The microscopy itself is continually being developed and the limits, which seemed to be insurmountable, have been overcome. The instruments have become user friendlier and their mobility enables flexible practical use in the field. The subject of this work is the design of a scanning electron microscope, the calculation of a magnetic curcuit of an immersion objective combined with standard lens, the theoretical calculation of a microscope resolution and the design solution of the mechanical parts of the microscope with a sample manipulator. The thesis includes a description of the electron microscopy development summarizing it briefly from the very beginning up to now. It also deals with electron sources, especially the Shottky cathode, which is to be the main object observed by the proposed device. The work also contains a description of the calculation of the microscope resolution as a function of the current density distribution. Another interesting issue included in the theoretical part is the signal detection, a description of several types of detectors and possible signal processing. The solution of the thesis includes a description of the concept of the scanning electron microscope with an explanation of the distribution of combined lens functions. The optical diagram shows the arrangement of the electron optics system and the distibution of pressure in the chamber of the microscope. The theoretical calculation is devoted to the magnetic curcuit design of the objective and to the resolution of the microscope for a given extent of working distances. Two modifications of the lens were designed – a standard simple objective and a combination of the standard objective with the immersion magnetic one. The results of both modifications are given for the parameters to be compared. The combined objective was designed with the possibility of use in two modes, as a standard and immersion lens. The deflection system is also divided into two modes, as a single deflection for the standard lens and as a two-dimension deflection for the immersion lens. Detectors for secondary electrons (SE) and detectors for back scattered electrons (BSE) will be used for the signal detection. The design of the microscope is another large part, which gives details on the most significant components of the microscope. The content of the technical solution is a three-dimensional computer model, created in Autodesk Inventor, which also includes a sample manipulator driven by piezoelectric actuators.
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Scanning Electron Microscopy and its Applications for Sensitive Samples
Hrubanová, Kamila ; Nováček, Jiří (referee) ; Schröfel,, Adam (referee) ; Krzyžánek, Vladislav (advisor)
Předložená dizertační práce s názvem “Rastrovací elektronová mikroskopie a její aplikace pro senzitivní vzorky” pojednává o problematice rastrovací elektronové mikroskopie v kontextu instrumentálního a metodologického vývoje vedoucího k inovativnímu řešení, které je dobře aplikovatelné zejména v mikrobiologickém výzkumu. Součástí práce je rozprava o historii a současném stavu elektronové mikroskopie (EM) jakožto vědecké zobrazovací a analytické techniky, tato část se nachází v úvodních kapitolách. Nepopiratelný přínos EM v biologických a lékařských oborech je dokazován mnoha citovanými vědeckými publikacemi. Předložená dizertační práce přináší novinky z oblasti přípravy preparátů a kryogenní rastrovací elektronové mikroskopie (cryo-SEM) vyvinuté na pracovišti Ústavu přístrojové techniky AV ČR, v.v.i. v Brně. Jedná se především o návrhy a výrobu speciálních držáků vzorků a vývoj nových metodik v oblasti přípravy mikrobiologických preparátů vedoucích k nalezení optimálních parametrů jednotlivých procesů. V experimentální části se nachází ověření metodologických postupů při studiu hydratovaných a na elektronový svazek senzitivních preparátů. Následné srovnání různých přístupů na definovaném biologickém systému z oblasti mikrobiologie přispívá k rozšíření interpretace doposud známých výsledků. Mezi zkoumanými mikrobiologickými kmeny byly biofilm-pozitivní bakterie Staphylococcus epidermidis a kvasinky jako Candida albicans a Candida parapsilosis, jež jsou považovány za klinicky významné, protože se podílejí na vzniku závažných infekcí zejména u imunokompromitovaných pacientů. Dále byl studován vliv růstu biofilmu bakterie Bacillus subtilis na biodeteriorizaci a biodegradaci poly--kaprolaktonových fólií. Vývoj v oblasti cryo-SEM byl aplikován ve výzkumu mikrobů s biotechnologickým potenciálem, jako jsou např. Cupriavidus necator a Sporobolomyces shibatanus.
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Rationalisation of production technology
Konečný, Petr ; Kolář, Ladislav (referee) ; Osička, Karel (advisor)
This thesis deals with the rationalization of production technology of selected component. The first part contains a brief introduction of the company NTS Prometal Machining s.r.o. and brief description of the product. The following section is an analysis of existing manufacturing technology. The practical part is focusing on the proposal of rationalization versions of the production process. After evaluation of all possible options of rationalization there has been developed a new technological process with a respect to time and cost savings. Finally there was carried out economical evaluation and recommendation for further production of this component.
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Generation of nanoparticles by electrical discharge in liquids
Čechová, Ludmila ; Horák, Jakub (referee) ; Kozáková, Zdenka (advisor)
This thesis focuses on the process of nanoparticle generation by electric discharge in liquids. The theoretical part is focused on generation of electric discharge in liquids, various methods of preparation of nanoparticles, including plasmachemical methods and methods of nanoparticle characterization. The experimental part deals with the preparation of silver nanoparticles. As a precursor for generation of nanoparticles by electric discharge, an aqueous solution of silver nitrate was used. The influence of experimental conditions, such as the influence of voltage polarity, influence of delivered power, effect of concentration, effect of added electrolyte and time course of nanoparticle formation were studied. All samples were analyzed by UV-VIS spectrometry. To confirm the presence of nanoparticles in the solution, one of the samples was analyzed by a scanning electron microscope with an energy dispersion spectrometer for elemental analysis. Plasma diagnostics was performed using optical emission spectroscopy.
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Comparison of the imaging capabilities of the transmission and scanning electron microscope
Maňka, Tadeáš ; Šamořil, Tomáš (referee) ; Zlámal, Jakub (advisor)
The aim of this work is to compare the imaging capabilities of the transmission and scanning electron microscope. The theoretical part describes the construction and the principle of each type of microscope. There is a list of the signal detectors, and the principle of imaging is described. The samples and their preparation are described. The practical part is aimed to imaging possibilities of both microscopes. A standard calibration samples were used for comparison. The advantages and disadvantages of both microscopes were discussed.
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Pumping analysis in the experimental chamber for electron microscope using ANSYS system
Dostalová, Petra ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
The thesis is focused on issue of pumping in the differential pumped chambre of an environmental scanning microcope. In the theoretical part, there are presented microscopy as science. Afterwards the thesis is focused on environmental scanning electron microscopy and its problem and vakuum system, computer program used for preparation of simulation and study that the experimental part is based on. The experimental part contains the results of gas flow in the differential pumped chambre. The problematics were solved by Ansys Fluent system.
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Processing of modern microscope signals for local material characterization
Kaspar, Pavel ; Sadovský, Petr (referee) ; Tománek, Pavel (advisor)
Signal processing from modern microscopes for local characteristics of materials Image processing is more and more important for the advancement of image evaluation taken from microscopes. This thesis engages the problem of artefact detection and removal from images taken by electron microscope, more accurately by low energy electron microscopy (LEEM). It then offers a possible course of processing such images by edge detection and its theoretical use. These operations are all made in MatLAB language.
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