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Utilizing of Electron Microscopy for Nanoparticle Detection in Selected Food
Boriková, Natália ; Hrabalová, Vendula (referee) ; Dzurická, Lucia (advisor)
This bachelor thesis deals with the detection of nanoparticles in selected food products using electron microscopy. Specifically, silver pearls, silver powder and food grade whiteness were selected for this purpose. Nanoparticles themselves can have a negative effect on the human body in high concentrations. They need to meet certain legislative standards. The main focus of this bachelor thesis is how nanoparticles could be detected in food. The theoretical part provides an insight into the properties of nanoparticles, their applications and describes methods for their determination, primarily with an emphasis on electron microscopy. In the practical part, solvents with artificially added nanoparticles were prepared and served as standards. Two samples were prepared from selected foods – with and without the addition of nanoparticles. They were analysed using low-energy electron microscope of LVEM 25E type along with elemental analysis using energy dispersive spectroscopy (EDS). The results provide the compositions of the foodstuffs in question and information on the presence of nanoparticles on their own. This research contributes to a better understanding of their characteristics and safety.
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Defect localization and analysis in GaN
Gazdík, Richard ; Šik, Ondřej (referee) ; Bábor, Petr (advisor)
Táto diplomová práca sa zaoberá lokalizáciou a analýzou vláknových dislokácií v epitaxných vrstvách GaN. Práca je rozdelená na dve časti - teoretickú a experimentálnu. V teoretickej časti je vysvetlený pôvod a povaha vláknových dislokácií. Okrem toho kladie základy pre lepšie pochopenie možno menej známych techník, ktoré sa dajú použiť na ich štúdium - zobrazovanie elektrónového kanálovacieho kontrastu a selektívne leptanie defektov. V experimentálnej časti sú popísané postupy vykonané pri realizácii týchto techník, ako aj pre TEM zobrazovanie difrakčného kontrastu a s ním spojenej prípravy vzoriek pomocou FIB. Ukazujeme, že každá z týchto techník sa môže použiť samostatne na charakterizáciu vláknových dislokácií, ale že ich kombináciou je možné získať doplňujúce informácie.
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Nanoparticels from brake pads wear
Švábenská, Eva ; Roupcová, Pavla ; Friák, Martin ; Schneeweiss, Oldřich
Exposure to particulate air pollution has been associated with a variety of health problems. One of the main\nsources of metal-rich airborne particulate pollution in roadside environments are brake-wear emissions. The \nscanning electron microscopy (SEM) and transmission electron microscopy (TEM), Mössbauer spectroscopy \n(MS), X-ray powder diffraction (XRD) was used to a make quantitative evaluation of wear particles in two \nsamples. Sizes, morphologies, oxidation state, and trace element compositions of wear particles were\ninvestigated using combination of several methods revealed high concentrations of Fe species and phases, \noften associated with carbonaceous material. SEM and TEM observations show that brake wear particles with \na size of tens to hundreds of nm mainly form particle agglomerates. However, ultrafine (<100 nm) particles are \nlikely to pose a health threat after inhalation and/or ingestion.
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SMV-2023-57: EM analysis of microorganisms II
Hrubanová, Kamila
The aim of the contract research was the expert analysis of microbiological samples with biotechnological significance with the intention of describing the ultrastructure of the cells, which depends on the cultivation conditions of the industrial process. The collaboration included cryogenic preparation of samples, followed by microbial microscopy using low-temperature electron microscopy (cryo-SEM), and selected samples were processed for transmission electron microscopy (TEM). Furthermore, spectroscopic measurements were performed using Raman spectroscopy.
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SMV-2023-56: EM analysis of microorganisms
Hrubanová, Kamila
The aim of the contract research was the expert analysis of microbiological samples with the intention of describing morphological changes dependent on culture conditions. The collaboration included cryogenic preparation of samples, followed by microbial microscopy using low-temperature electron microscopy (cryo-SEM), and selected samples were processed for transmission electron microscopy (TEM). Furthermore, spectroscopic measurements were performed using Raman spectroscopy.
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Application of Technique of Oriented Foils in TEM
Buček, Petr ; Kruml, Tomáš (referee) ; Petrenec, Martin (advisor)
The master’s thesis is focused on the application of the technique of oriented foils in transmission electron microscopy. Dislocation structures were identified by this technique in both phases of polycrystalline austenitic-ferritic stainless steel SAF 2507 formed during low cycle fatigue at two plastic strain amplitudes ap. In individual grains the stress axis and the Schmid factors of active slip systems were determined. In austenitic grains, the planar structures were determined at both ap. In ferritic grains, the dislocation arrangement was different for the two observed ap. Individual screw dislocations and pile-up´s of edge dislocations were found at low ap = 1x10-4. Mixture of vein and wall dislocation structures were formed at high ap = 2x10-3. Observed dislocation structures were discussed in relation with the cyclic plastic response of the duplex stainless steel.
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Characterization of scanning transmission electron microscopy images of thin biological sections
Novotná, Veronika ; Nebesářová,, Jana (referee) ; Krzyžánek, Vladislav (advisor)
Diplomová práce popisuje fyzikální principy mikroskopů TEM, SEM a STEM spolu s jejich vhodností pro pozorování vzorků citlivých na elektrony, jako jsou zalévací média či biologické vzorky. Dále je popsána příprava vzorků pro STEM (TEM) a popis interakcí, ke kterým dochází mezi primárním elektronovým svazkem a vzorkem. Součástí práce je také pojednání o zpracování mikroskopických obrazů s podkapitolou o metodách kvantitativního porovnání obrazů ze STEM. Praktická část práce je zaměřena zejména na měření úbytku hmoty zalévacích médií (Epon, Spurr, LR White) způsobený primárním svazkem elektronů v nízkonapěťovém STEM. Ultratenké řezy několika tlouštěk byly zkoumány při různých nastaveních mikroskopu (urychlovací napětí, celková dávka, proud svazku, čištění povrchu vzorku a komory mikroskopu) a zobrazovacích módech (světlé a tmavé pole). Dále jsou zkoumány také biologické vzorky Krásnoočka štíhlého (Euglena gracilis) zalitého v pryskyřicích Epon a Spurr. Nasbírané snímky, vytvořené algoritmy a získané výsledky jsou diskutovány a zhodnoceny.
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Investigation of Functional Properties of Thin NiTi Filaments for Applications in Smart Structures and Hybrid Textiles
Pilch, Jan ; Dlouhý, Antonín (referee) ; Heczko,, Oleg (referee) ; Pokluda, Jaroslav (advisor)
PhD thesis focuses the field of textile application of modern functional materials, namely metallic shape memory alloys with unique thermomechanical properties deriving from martensitic transformation in solid state. Particularly, it deals with the development of a nonconventional thermomechanical treatment of thin NiTi filaments via Joule heating by electric current and related basic research involving thermomechanical testing and modeling of functional properties of the filaments, investigation of martensitic transformations and deformation processes in NiTi and investigation of the fast recovery and recrystallization processes in metals heated by short pulses of controlled electric power. The method was developed and called FTMT-EC. In contrast to conventional heat treatment of metallic filaments in environmental furnaces, this method allows for precise control of the raise of the filament temperature and filament stress during the fast heating (rate ~50 000 °C/s). As a consequence, it is possible to precisely control the progress of the fast recovery and recrystallization processes in heat treated filaments. In this way it is possible to prepare filaments with desired nanostructured microstructure and related functional properties. A prototype equipment for application of the method for heat treatment of continuous SMA filaments during respooling in textile processing was designed and built. Comparing to the conventional heat treatment of SMA filaments in tubular environmental furnaces, this approach is faster, saves energy and allows for preparation of filaments with special functional properties. International patent application was filed on the method. It is currently utilized in the research and development of smart textiles for medical applications.
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Measure the impact of wireless technologies on TEM
Prokop, Martin ; Čudek, Pavel (referee) ; Polsterová, Helena (advisor)
The purpose of this diploma thesis is to research and compare available wireless communication technologies (frequency, modulation type, transmission speed and consumption). Describe transmission electron microscopes theory and deduce the most sensitive microscope parts to high frequency distortion. Investigate effect of wireless technology on CE standards and come up with, perform and evaluate the influence measurement of chosen technologies on base parameters of transmission electron microscope.
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Complementary analysis of procaryotic cells by electron microscopy and Raman spectroscopy
Ikrényiová, Terézia ; Sedláček, Petr (referee) ; Hrubanová, Kamila (advisor)
This master thesis deals with conventional methods of bacterial cell analysis, polyhydroxyalkanoates, Raman spectroscopy and electron microscopy in the theoretical part. The production of polyhydroxybutyrate by selected thermophilic bacteria and their analysis by gas chromatography, cryogenic scanning electron microscopy and Raman spectroscopy is described in the experimental part. The chosen sample was analyzed by a transmission electron microscope. Comparing the results from previous mentioned methods it was found that the bacteria Schlegelella thermodepolymerans accumulated the highest amount of PHB. The lowest amount of PHB was obtained by bacteria Rubrobacter xylanophilus. The assumption that the PHB granules formed so-called needle-like plastic deformations during freeze-fracturing was affirmed by cryo-SEM photos analysis. Moreover, it was found that the bacterial cell characterization deduced from microscopic observation of samples corresponded to the description in the literature. TEM provided better resolution photos and in consequence the cells and PHB are more visible. The thesis is also focused on chemical fingerprint analysis of cells by Raman spectroscopy. Several biomolecules were identified by measured Raman spectra for the particular samples.
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