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In vivo study of diatom assemblages using low temperature method for ESEM
Tihlaříková, Eva ; Neděla, Vilém ; Fránková, Markéta
Diatoms are the most species-rich algal group represented by 12 000 described species and are recognized as powerful bio indicators and used for water quality monitoring. Diatom taxonomy is predominantly based on the morphology of ornate silicified cell wall called frustule composed of two overlapping parts (thecae). This frustule displays intricate patterns and designs unique to each species. For these studies conventional scanning electron microscopy (SEM) was and still is widely used. This method requires cleaning of diatom frustules in strong acids and peroxides followed by conductive coating.This aggressive procedure removes protoplast and damages delicate structures. Environmental scanning electron microscopy (ESEM) brings advantages of observation of fresh diatom material that are presence of whole intact diatom cells, not only empty diatom frustules, extracellular mucilaginous diatom secrets (e.g. pads, stalks, tubes) and whole diatom assemblages directly in situ together with other algal assemblages (e.g. cyanobacteria or green algae). However, in diatom research, ESEM is used mainly for elimination of conductive coating and observation of these organisms in their native wet state adhered directly on the host plant is not yet common. The ESEM observation of native aquatic samples is usually affected with radiation damage that can be lovered by the use of special methods like the Low Temperature Method (LTM) for the ESEM.
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Optimization of scintillation detector for detection of low energy signal electrons in electron microscopy
Tihlaříková, Eva ; Kadlec, Jaromír (referee) ; Uruba, Václav (referee) ; Neděla, Vilém (advisor)
The dissertation thesis deals with optimization of the scintillation detector for efficient detection of low energy signal electrons in a specimen chamber of a scanning electron microscope. The solution was based on the study of signal electron energy loss mechanisms during their interaction with a conductive layer and a scintillator that can be studied using simulations based on the stochastics Monte Carlo methods. Based on test simulations and their comparison with experimental data, the ideal Monte Carlo software was chosen and used for the study of signal electron energy losses during their transport through the conductive layer as well as following interaction with scintillator, in dependency on the signal electron energy. Simulation results allowed to define criteria for the optimization of the conductive layer. According to these parameters, the optimized layers were deposited on the surface of different scintillators and experimentally tested in the scintillation detector of the scanning electron microscope. Experimental measurements allowed to verify accomplished simulations and provide new information about impact of materials and thicknesses of conductive layers in combination with materials of scintillators and light guides. The increase of the detection efficiency of the scintillation detector equipped with optimised conductive layers and its capability to detect low energy signal electrons were experimentally proved.
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Comparison of microscopic diagnostic methods
Veselý, Jakub ; Tihlaříková, Eva (referee) ; Čudek, Pavel (advisor)
This thesis deals with the description and comparison of diagnostic methods, transmission electron microscopy, scanning electron microscopy and atomic force microscopy. The introduction is a description of diagnostic methods. The following experimental section dealing with the diagnosis of ferritic chromium steel sample methods of scanning electron microscopy, atomic force microscopy, transmission electron microscopy and the evaluation and interpretation of measured results. The conclusion provides a comparison, the advantages and disadvantages of diagnostic methods.
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Scintillation SE Detector for Variable Pressure SEM
Tihlaříková, Eva ; Neděla, Vilém (referee) ; Jirák, Josef (advisor)
This project deals with the theme of environmental scanning electron microscopy (EREM). This method allows the examination of insulators and wet specimens without pretreatment and modification like drying and metallization. The principle of this method consists in using higher pressure in a specimen chamber. The pressure is within the range of 100 – 200 Pa. However, the pressure in the specimen chamber restricts the signal detection interference. The objective of the work is to explore the possibility of interference in secondary electron route detection by way of electrostatic field. The electrostatic field was realized with the system consisting of four electrodes located in front of the scintillation detector. It should have interfered the secondary electron´s trajectory to the detector chamber. The optimization of voltage on the electrodes was made by simulation program called SIMION. The simulation results were experimentally verified with laboratory EREM.
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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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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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Electron Microscopy as Unreplaceable Method in Parasitology: SEM and ESEM Utilization
Mašová, Šárka ; Foitová, I. ; Tihlaříková, Eva ; Neděla, Vilém
Systematic parasitology studies diversity and its origin. It includes mainly collection, naming, classification and describing of different species of parasites as well as a reconstruction of their evolutionary history. SEM is very important method in study and describing new species or redescribing insufficiently described species of parasites, because it empower opportunities for more detailed studies of their outer morphology. This method was applied in our research mainly for study of several species of parasitic roundworm (Nematoda) and one species of spiny headed worm (Acanthocephala). Our second topic concerning with SEM in parasitology is orangutan self-medication by plants with mechanical influence. However this method condemns parasite samples for destroying and do not allow other using of it. In case of specimens deficiency, environmental scanning electron microscopy (ESEM) is helpful. It would speed up a preparation of sample and is not invasive so valuable specimens can be used for other types of taxonomical studies. Non-invasivity of this method is shown in. Two species of already fixed roundworms (Multicaecum heterotis, Contracaecum osculatum) and one species of spiny headed worm (Corynosoma pseudohamanni) were documented also by ESEM. The samples were examined on a non-commercial ESEM AQUASEM II, they were placed to the Peltier specimen holder with silicon surface, into a drop of water. Observation conditions were: beam accelerating voltage 20 kV, probe current 50 pA, sample temperature 2°C, water vapour pressure 680 Pa. ESEM seems to be good alternative to classical SEM, in a case of lack of samples or need to use samples for molecular study or depositing them as type material in museum.
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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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