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Srovnání podmínek proudění plynu v detektoru při užití clonky a síťky
Hubáček, Jiří ; Špinka, Jiří (oponent) ; Maxa, Jiří (vedoucí práce)
V diplomové práci je nejprve popsána problematika elektronové mikroskopie a fyzikální model proudění tekutiny. Následně je v programu SolidWorks vytvořen zjednodušený trojrozměrný model scintilačního detektoru ve variantách se clonkou s jedním větším otvorem a síťkou se 300 malými otvory, přičemž obě varianty mají ve výsledku shodnou průtočnou plochu. Tyto modely jsou pomocí systému Cosmos FloWorks podrobeny analýzám zaměřeným na zkoumání proudění plynů, a to při různých tlacích v komoře vzorku EREM. Výsledky analýz obou variant clonek jsou porovnány vzhledem k požadavku, aby na dráze sekundárních elektronů a v komoře vzorku byl co nejnižší tlak.
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Pozorování izolantů v ESEM
Matějka, Milan ; Špinka, Jiří (oponent) ; Jirák, Josef (vedoucí práce)
Diplomová práce se v teoretické části zabývá principem a problematikou detekce signálních elektronů v rastrovací elektronové mikroskopii a problematikou projevů nabíjení izolačních vzorků. V experimentální části je popsána metodika kvalifikace a kvantifikace projevů nabíjení izolačního vzorku pozorovaném v environmentálním rastrovacím mikroskopu pomocí ionizačního a scintilačního detektoru v závislosti na tlaku vodních par v komoře vzorku. Cílem práce je vytvoření metodiky vhodné pro vyhodnocení nabíjecích projevu při pozorování u izolačních vzorku a na základě měření, stanovení optimálních podmínek pozorování izolantů v EREM pro ionizační a scintilační detektor.
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Analysis of the gas glow
Hladká, K. ; Maxa, J. ; Neděla, Vilém ; Vyroubal, P. ; Vaculík, S. ; Hlavatá, P.
In order to optimize the shape of the Differentially pumped chamber in the area of the Primary Electron Beam passage for the current concept of the location of the foci of the Primary Electron Beam, it was necessary to adapt to the size and shape of the limitations of the existing structure. On fig. 1a is the total cross sectional view of the Differentially pumped chamber. Three variants were examined: Current concept with an easily machined shape of the passage of the primary beam, semi-closed concept with a conical shape, cone concept with a wider cone.
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Use systems for the analysis of gas flow
Maxa, J. ; Neděla, Vilém ; Hladká, K. ; Vyroubal, P. ; Vaculík, S. ; Hlavatá, P.
Environmental scanning electron microscope is explaining withdrawing of two differentially pumped chambers in a drawing area. To solve this problem is used finite volume method. This method includes several steps: - With using of mesh the area is dividing into discrete volume. - Discretization and balancing of the unknown quantities in each finite volume - Numerical solution of discretized equations.
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Physical and biocatalytic properties of polyvinyl alcohol lens-shaped particles versus spherical polyelectrolyte complex microcapsules
Schenkmayerová, A. ; Bučko, M. ; Gemeiner, P. ; Treľová, D. ; Lacík, I. ; Chorvát Jr., D. ; Ačai, P. ; Polakovič, M. ; Lipták, L. ; Rebroš, M. ; Rosenberg, M. ; Štefuca, V. ; Neděla, Vilém ; Tihlaříková, Eva
Direct comparison of key physical and chemical-engineering properties of two representative matrices for multipurpose immobilisations was performed for the first time. Polyvinyl alcohol lens-shaped particles LentiKats and polyelectrolyte complex microcapsules were characterised by advanced techniques with respect to the size distribution of the particles, their inner morphology as revealed by fluorescent probe staining, mechanical resistance, size-exclusion properties, determination of effective diffusion coefficient and environmental scanning electron microscope imaging. Recombinant cells E. coli overexpressing enzyme cyclopentanone monooxygenase were immobilised in polyelectrolyte complex microcapsules and LentiKats for comparison of their operational stability using model Baeyer-Villiger oxidation of (±)-cis-bicyclo[3.2.0]hept-2-en-6-one to regioisomeric lactones as important chiral synthons for potential pharmaceuticals.
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Progress in imaging techniques for characterization of polyelectrolyte complex microcapsules as encapsulation matrice for biocatalysts
Bučko, M. ; Gemeiner, P. ; Vikartovská, A. ; Schenkmayerová, A. ; Bertóková, A. ; Lacík, I. ; Chorvát Jr., D. ; Neděla, Vilém
Polyelectrolyte complex microcapsules showed to be an univerzal encapsulation matrice for wide range of biocatalysts including viable, native and recombinant bacterial cells, non-viable bacterial cells as well as enzymes. Developed continuous encapsulation protocol based on the polyelectrolyte complexation of oppositely charged polymers enabled production of uniform microcapsules with a controlled shape, size, membrane thickness, permeability and mechanical resistance. The characterisation and control of the microcapsule properties including the inner structure and surface properties was inevitable to determine their proper function and predictability in important applications such as the stabilisation and reuse of encapsulated biocatalysts for more efficient production of valuable compounds. Recent utilisation of unique environmental scanning electron microscope enabled an innovative observation and characterization of capsule morphology in native and fully hydrated state. Achieved results and comparison with previously used conventional microscopic techniques will be presented.
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Ice and its impurities from the perspectives of photochemistry and electron microscopy
Heger, D. ; Krausko, J. ; Klán, P. ; Runštuk, Jiří ; Neděla, Vilém
Ice as a solid phase of water is an interesting but still not well understood medium. Our photochemical group utilized chemical and spectroscopic tools to acquire information relevant to the environmental and applied science. In the introduction I would like to stress some important facts on ice and frozen aqueous solutions stemmed from our work. Still opened question, that we are trying to answer by the ESEM, is where and at what forms are the impurities located after the freezing. The recently published results from the pilot collaboration with Dr. Neděla’s group will be detailed.
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Using environmental scanning electron microscopy (ESEM) as a non-invasive method to studying fixed parasites
Mašová, Šárka ; Neděla, Vilém ; Tihlaříková, Eva
Scanning electron microscopy (SEM) is popular and for taxonomy of parasites very important and not substituted method in many times. However sometimes taxonomists have only one specimen and cannot use classical SEM, because their sample (poor conductor) have to be fixed, dehydrated and coated before it can be observed. This method condemns samples for destroying and do not allow other using of it, e.g. for molecular study or depositing as type material in museum. Moreover, the specimen preparation is often long and slow. Environmental scanning electron microscopy (ESEM) brings two main advantages: elimination of speed of sample preparation and non-invasivity.
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The Study of Ice Impurities Using the Environmental Scanning Electron Microscopy at Higher Pressures and Temperatures
Neděla, Vilém ; Runštuk, Jiří ; Klán, P. ; Heger, D.
Natural ice and snow accumulate and concentrate significant amounts of impurities that can be stored or chemically transformed, and eventually released to the environment. The location of impurities and their interactions with the water molecules of ice have not yet been sufficiently clarified. The aim of this work is to observe an uranyl-salt brine layer on the ice surface using a back scattered electron detection and the ice surface morphology using a secondary electron detection under equilibrium conditions in a specimen chamber of environmental scanning electron microscope (ESEM). Our specially modified ESEM AQUASEM II equipped with the YAG:Ce3+ backscattered electron detector, an ionization detector of secondary electrons, a special hydration system and a Peltier cooled stage was used. The pressures between 400-700 Pa, 50% water-vapor saturation, and the temperatures above 250 K were utilized in our experiments. At these conditions, the phenomena of etching and subsequent stripping of impurities are largely suppressed.
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Workshop of Interesting Topics of SEM and ESEM
Neděla, Vilém ; Mašová, Šárka ; Tihlaříková, Eva
The book of abstracts from the Workshop of Interesting Topics of SEM and ESEM includes original English written papers focused on new results of Environmental electron microscopy group from the ISI ASCR in Brno ant scientific and industry partners of this group. This book contain new results from the field of instrumentation, biology, physics and chemistry. The overall objectives of the workshop were to provide space for exchanging news, ideas, advice and experience in the field of Electron Microscopy which can lead to mutual future scientific collaboration. This workshop has been organized as a forum of state-of-the-art discussion in a number of topics which will be covered by several distinguished invited talks and other presentations.
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