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Production and storage of hydrogen
Krátký, Štěpán ; Lízal, František (referee) ; Hejčík, Jiří (advisor)
The goal of this bachelor’s thesis is to make an overview of current technologies used to produce and store hydrogen. First part deals with production technologies. Hydrogen production is divided into three categories: production of hydrogen from fossil fuels, from water and from BIO sources. Second part is dedicated to storage technologies and contains the most known methods of hydrogen storage.
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Interference study for lead determination using hydride generation technique coupled with AAS detection
Hillmich, Ondřej ; Hraníček, Jakub (advisor) ; Musil, Stanislav (referee)
This bachelor thesis is focused on the interference study of different elements during lead determination using hydride generation technique. For this method tetrahydroborate was used as a reduction agent and hexacyanoferrate as an oxidant agent which dramatically increases efficiency of plumbane formation. Before interference study, significant experimental conditions were optimized. The optimizations include flow rate of carrier gas (argon), concentrations and flow rates of all reagents (HCl, NaBH4, K3[Fe(CN)6]), atomization temperature and volume of sample loop. Under the optimal experimental conditions, the calibration was constructed and basic characteristics of the method were determined - sensitivity (0.0012 l∙μg-1 ), limit of detection (3.13 μg∙l-1 ). For interference measurement another hydride-forming elements (As, Se, Sb, Sn, Bi, Te), significant transition metals (Fe, Ni, Cu, Zn), alkali metal and alkaline earth metal (Na+ , Ca2+ ) and common anions (Cl- , SO4 2- , NO3 - ) including acetate anions were selected. Acetate anionswas incorporated to the study as a representative organic molecule. Hydride-forming elements, mainly selenium, were found as most serious interferents. E.g. selenium at low concentration increases absorption signal of lead. On the other hand, selenium at high...
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Superconductivity and electronic properties of y-U alloys and their hydrides
Tkach, Ilya ; Havela, Ladislav (advisor) ; Mihálik, Marián (referee) ; Schneeweiss, Oldřich (referee)
Title: Superconductivity and electronic properties of γ-U alloys and their hydrides. Author: Ilya Tkach Department / Institute: Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Doc. RNDr. Ladislav Havela, CSc., Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Prague, The Czech Republic Abstract: Low-temperature electronic properties for U-Mo and U-Zr splats stabilized in γ-U were investigated. Magnetic measurements revealed Pauli paramagnetic behavior with temperature independent susceptibility for U-Mo alloys. U-Mo and U- Zr splats become superconducting at low temperatures with Tc up to 2.1 K and critical field 5-6 T. The superconductivity of -U can be considered as a bulk effect and can be described by the BCS theory, while -U superconductivity is not a real bulk effect. U-Mo and U-Zr alloys absorb hydrogen at high pressures (p ≥ 4.5 bar) and form hydrides with stoichiometry analogous to UH3. The hydrides with Mo have an amorphous structure based on β-UH3 phase, while hydrides with Zr have a crystalline structure of the -UH3 type. (UH3)1-xMox hydrides are ferromagnetic with enhanced TC up to 202 K and magnetic moments 1.1 μB/U in comparison with pure β-UH3 (175 K; 0.87 μB/U)....
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Construction of miniature flow-through cells for electrochemical generation of volatile compounds
Hraníček, Jakub ; Rychlovský, Petr (advisor) ; Spěváčková, Věra (referee) ; Komárek, Josef (referee)
(EN) The presented dissertation thesis summarizes the new results of electrochemical generation of volatile compounds usable in atomic spectral methods. The main aim of this work is to develop and to characterize new types of electrolytic flow-through cells and to examine their possibilities of determination of arsenic, selenium and antimony by using the electrochemical hydride generation technique coupled with atomic absorption spectrometry with a quartz tube atomizer. Individual electrolytic cells were designed and constructed to comply with two important requirements. The cathode chamber of the electrolytic cell should have a minimal volume and a high efficiency of analyte conversion to the volatile hydride. Constructed electrolytic cells are divided into the construction groups and described in the experimental part. Selenium was chosen as the first analyte. The relevant working parameters (such as type, concentration and flow rate of electrolytes, generation current and carrier gas flow rate) were optimized for each newly constructed electrolytic cell. Under the optimal working parameters, the basic characteristics of selenium determination were found out by using electrochemical hydride generation. The electrolytic cells were compared to each other and with the classical electrolytic cell...
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Production and storage of hydrogen
Krátký, Štěpán ; Lízal, František (referee) ; Hejčík, Jiří (advisor)
The goal of this bachelor’s thesis is to make an overview of current technologies used to produce and store hydrogen. First part deals with production technologies. Hydrogen production is divided into three categories: production of hydrogen from fossil fuels, from water and from BIO sources. Second part is dedicated to storage technologies and contains the most known methods of hydrogen storage.
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