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Research on the content of risk elements in the material of PET bottles
Kryštofová, Petra ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This thesis deals with the research of the content of risk elements in the material of rPET (recycled polyethylene terephthalate), supplied from various countries, and the study of different factors (type of liquid, temperature) on the migration of antimony from this material. The recycling process has the potential to increase the content of unwanted substances and promote the formation of degradation products of chemical additives and by-products of polymerization, thus contributing to higher migration of these substances into food or food simulants [1]. The supplied rPET samples were subjected to total decomposition in an environment of concentrated sulfuric and nitric acid under the influence of microwave radiation prior to analysis. Prepared samples were analyzed by atomic absorption spectroscopy (AAS) techniques. The contents of Sb and Zn were determined by flame atomic absorption spectrometry (FAAS), and the concentrations of Pb, Cu, Zn, Cd, Cr, and Ni were determined by electrothermal atomic absorption spectrometry (ETAAS). Additionally, the concentrations of Sb were determined by this method in migration experiments. This thesis builds upon the author's bachelor's thesis, which included pilot experiments.
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Low-temperature plastic deformation of BCC metals with internal magnetic order
Holzer, Jakub ; Máthis,, Kristián (referee) ; Mrověc, Matouš (referee) ; Gröger, Roman (advisor)
Přestože plastická deformace kovů s prostorově střeďenou kubickou mřížkou za nízkých teplot je dnes dobře vysvětlena, vliv vnitřního magnetického uspořádání na mechanické vlastnosti a vliv plastické deformace na vnitřní magnetické uspořádání zůstávají z větší časti nevysvětleny. Cílem této práce je popsat nízkoteplotní plastickou deformaci -železa a chromu pomocí analýzy skluzových čar, elektronovou zpětně odraženou difrakcí a transmisní elektronovou mikroskopií (TEM). Vnitřní magnetické uspořádání chromu je zkoumáno pomocí magnetické neutronové difrakce v neutronovém centru na Institutu Paula Scherrera ve Švýcarsku. Vibrační magnetometrie je využita pro hledání změn v hmotnostní susceptibilitě, aby byly rozeznány různé magnetické stavy. Anomální skluz byl poprvé pozorován v deformovaném vzorku chromu. Dislokační síť zodpovědná za anomální skluz je charakterizována pomocí g·b analýzy v TEM. Síť protínajících se 1/2111 šroubových dislokací a jejich 100 spoje se tvoří na nízkozatížených {110} rovinách. Dvojčata vytvořená antidvojčatovým smykem byla pozorována v chromu, ale nikoliv v -železe. Tento jev je vysvětlen pomocí atomárních simulací využívajících semiempirické interakční potenciály. Magnetické domény v -železe byly studovány pomocí Kerrovy mikroskopie. Výsledky ukazují, že dvojčata mohou efektivně blokovat pohyb doménových stěn a nukleovat nové.
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Speciation analysis of chromium in particulate matter of urban dust
Rybínová, Marcela ; Rychlovský, Petr (advisor) ; Hraníček, Jakub (referee)
Anion-exchange chromatography with inductively coupled plasma - atomic emission spectrometry (ICP-AES) has been used for the speciation of chromium (Cr). Chromium speciation has attracted attention because of the different toxicity, Cr(III) is relatively non-toxic and Cr(VI) has been classified as a human carcinogen. The aim of the present study was to develop simple method for the speciation analysis of Cr (Cr(III) and Cr(VI)) in particulate matter of urban dust. A combination of 2% KOH + 3% Na2CO3 has been chosen as the optimal reagent for the extraction of chromium from particular matter. It was found that there was no conversion of Cr(VI) into Cr(III). The effect of separation parameters such as acidity of mobile phase was also studied. The detection limit for Cr(VI) was about 12 ng.ml-1 . Results for the determination of Cr(VI) were confirmed by the analysis of standard reference material (BCR CRM 545, Cr(VI) in welding dust loaded on a filter) with good agreement between certified (40,16 ± 0,60 μg.g-1 ) and found (37,83 ± 1,14 μg.g-1 ) values.
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Application of Atomic Absorption Spectrometry for Determination of Selected Elements from Potential Ecological Burden Area
Juránková, Lada ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
This work is focused on the determination of selected (chemical) elements (Fe, Mn, Zn, Cr, Na, K, Mg a Ca) in a potential ecological burden area using flame atomic absorption spectrometry as a detection technique. A potential ecological burden is represented by tires which are used as a construction material or as an environment surrounding for growing decorative and consumable plants. Analytes were determined in plant origin samples. Firstly, the samples were dried in a laboratory electric dryer. The weighted amount of a dried sample (approximately 0.2 g) was digested inside a microwave decomposition device with an addition of nitric acid and hydrogen peroxide. An optimization of experimental parameters was done for each of the elements before sample measuring. A burner height was optimized and 8 mm height was chosen as a optimum for most elements. Under the optimum condition basic characteristics were measured for each element separately. These characteristics included limits of detection that were: 0.05; 0.01; 0.08; 0.21; 0.02; 0.01; 0.01; 0.01 mg L-1 for the following elements: Fe, Mn, Zn, Cr, K, Ca, Mg and Na, respectively. The limits of quantification, sensitivity and repeatability were determined for each element as well. A significant attention was paid to the content of zinc in the studied...
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Methods of Data Extraction from the Web
Perina, Lukáš ; Křivka, Zbyněk (referee) ; Burget, Radek (advisor)
The purpose of this bachelor thesis is to design an architecture and subsequent implementation of an application designed for data extraction (web scraping) from web documents. Unlike conventional methods, it is an extraction based on defining data types and regular expressions of requested elements. Extraction is executed in such a manner, where it is not necessary to know the detailed structure of given web document and the possibility of using just one definition to detect requested elements on different web pages. Algorithm is able to achieve overall accuracy of 85,51% and recall 80,28%. This approach can reduce the time required for analysis of web pages significantly and not to take the structure of the code as a determining factor while creating web scraping requests.
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Processing and properties of transparent polycrystalline ceramic materials
Tásler, Jan ; Pouchlý, Václav (referee) ; Maca, Karel (advisor)
The presented diploma thesis is focused on the preparation and properties of transparent polycrystalline ceramic materials based on Al2O3. Theoretically, the most important technological aspects of the processing of these materials are presented. Detailed attention is given to transparent Al2O3 polycrystalline ceramics doped with rare earth elements. The influence of microstructural parameters on the optical properties (represented by RIT) is investigated on Al2O3 samples doped and codoped with dysprosium, terbium and chromium. A significant effect of the average grain size on the light transmittance of all samples is observed. The highest RIT = 55 % (measured by a laser beam with a wavelength of 632,8 nm) was achieved by an optimized preparation process for a sample doped with 0,05 at. % of dysprosium. For all samples photoluminescent properties are also analysed. The photoluminescent emission spectra correspond to the activation of doping elements. In case of the terbium and chromium codoped samples, the differences in the activation of individual dopants depending on different excitation wavelengths were demonstrated, resulting in different colour emissions for different excitation wavelengths.
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The pilot plant scale of the electrochemical elimination of Cr and Ni
Krušinová, Zuzana ; Klusoň, Petr (advisor) ; Žebrák, Radim (referee)
Electrocoagulation is a progressive yet not thoroughly understood method used to purify water contaminated by toxic elements and compounds. This bachelor thesis is focused on pilot scale testing of the electrochemical elimination of chromium and nickel from groundwater, realized on the premises of the company Velobel in Zlaté Hory. Firstly, it was essential to optimize the electrocoagulation process according to the parameters and composition of the groundwater. Secondly, it was necessary to test a continuous long-term operation that would make possible complete decontamination of the site. The electrocoagulation process was followed by addition of flocculant which was used to promote the sedimentation of the sludge. Lime solution was added simultaneously to change pH and to help eliminate nickel. This was followed by sedimentation and the purified water was led away by an overflow. The sludge was treated by a filter-press. Hexavalent chromium content in water samples was analysed spectrophotometrically with diphenylcarbazide, whereas trivalent chromium, nickel, zinc and manganese were analysed in a laboratory using ICP-OES (inductively coupled plasma - optical emission spectrometry). It was discovered that the tested technology is very successful in real conditions, with metal removal efficacies...
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Design of a software for emulation of rendering a web page
Čech, Miroslav ; Pavlíčková, Jarmila (advisor) ; Pokluda, Václav (referee)
The author of this thesis aims to analyze and develop a prototype of a software responsible for showing how the specific web application would be displayed by the concrete device. First, the problem of diversity of devices for accessing the web and of the level of support of modern web technologies is explained to the reader. Then the thesis offers a way how to help developers with testing across web browsers on different hardware. The analytical section describes the methods the author would like to use for accomplishing the goal, and also the set of suitable technologies. The penultimate section shows the manner the author implemented the prototype of the software. The Software is then subjected to tests showing that the prototype meets the requirements.
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