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EFFECT OF STEEL COMPOSITION ON ITS BEHAVIOUR IN THE LIQUID LEAD ENVIRONMENT
Pazderova, M. ; Hojná, A. ; Vít, J. ; Hadraba, Hynek ; Čižek, J.
Ferritic-martensitic Eurofer-97 and oxide dispersion strengthened (ODS) Eurofer steels are potential candidates for structural applications in advanced nuclear reactors. Influence of scandium, yttrium, and aluminum addition was studied at 600 degrees C using 10-6 wt.% oxygen concentration. Microstructure and corrosion behaviour was evaluated after 500 h and 1000 h of exposure to liquid lead. Microscopical investigation identified oxidation, solution- based attack, and Pb penetration into the material. Addition of scandium and aluminum changed the mechanism of corrosion attack. Eurofer-97 was partially protected by outer oxide and inner oxidation and Pb penetration was found. In contrast ODS-Eurofer steels after 1000 h of exposure showed mainly inner oxidation and SBA including Pb penetration into the steel. The inner oxidation consisted of Pb+Cr-O and Cr-O+Al-O layers mixture. Degradation of ODS steel was significantly lower than Eurofer-97. It seems that the inner oxidation layer beneath the surface did not prevent the Pb penetration but protected the surface from dissolution.
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Impact of the Number of Measurements on Result Distortion
Kuchařík, Jan ; Šimek, Antonín
This study investigates the distortion of results due to the number of corrosion current measurements. Samples were prepared by pressing and subsequently sintering iron and magnesium powders. The samples were then immersed in an SBL solution at 37 °C. Measurements took place over 23 days. For two samples, measurements were taken each time, while the remaining samples were measured in sequence on their respective days.
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Voltammetric detection of 27-hydroxycholesterol on boron-doped diamond electrode
Michnová, Kristýna ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this bachelor thesis was to study the voltammetric behavior of 27-hydroxycholesterol using boron-doped diamond electrode. The influence of several factors on the current response of 27-hydroxycholesterol was investigated: the effect of the supporting electrolyte, concentration of perchloric acid, polarization rate, water content, and pH effect. The study was conducted using cyclic voltammetry in a perchloric acid or sodium perchlorate in acetonitrile. 27-hydroxycholesterol provided a current response in the anodic region with a potential around +1450 mV vs. Ag/0.01 mol l-1 AgNO3 in 1 mol l-1 NaClO4 in acetonitrile in the presence of 0.1 mol l−1 perchloric acid in acetonitrile (water content 0.43 %) and 0.1 mol l−1 sodium perchlorate in acetonitrile. Furthermore, concentration dependence was measured using differential pulse voltammetry resulting in a limit of detection (LOD) of 2.71 μmol l−1 and a limit of quantitation (LOQ) of 9.04 μmol l−1 . It was demonstrated that the direct current voltammetry method does not achieve comparable limit values. Key words 27-hydroxycholesterol, boron-doped diamond electrode, oxidation, oxysterols, voltammetry
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Reaction Mechanisms of Psychoactive Compounds
Sokolová, Romana ; Beneš, Marek ; Jiroušková, Eliška ; Degano, I.
The reaction mechanism of selected new psychoactive substances (NPS) 4-methylpentedrone and 2-(((4-ethyl-2,5-dimethoxyphenethyl)amino)methyl)phenol was investigated based on their\nelectrochemical and spectroelectrochemical properties. Both drugs were examined by means of cyclic voltammetry using diagnostic parameters for particular reaction schemes, UV/Vis, and IR\nspectroelectrochemistry. Since water participates in the redox mechanism of both studied compounds, the reaction mechanism was studied under a controlled amount of water in an\nacetonitrile environment.
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Oxidation behavior adjustment for TiAl intermetallics by Al-Y multilayers
Handrk, Jiří ; Tkachenko, Serhii (referee) ; Jan, Vít (advisor)
Mechanické vlasnosti intermetalika na bázi titan hliník Ti-46Al-7Nb-0.7Cr-0.1Si-0.2Ni jsou konstatní do teploty 700 °C. Nad touto teplotou slitina oxiduje. Cílem této práce bylo zlepšit oxidační vlastnosti pomocí kovové multivrstvy na bázi yttrium hlinik. Pro depozici vrstev byla použita metoda PVD. Na vzorky byly naneseny vrstvy čistého ytria nebo kombinace yttrium, hliník. Vzorky byly následně žíhány v inertní atmosféře na 700°C a 900°C nebo nebyly. Kvalita nanesených vrstev byla zkoumána pomocí scratch testu a EDS analýzi. Dále byly vzorky izotermicky oxidovány na 900°C po dobu 100 hodin. Na vzorcích byly po oxidaci prováděny měření pevnosti v tříbodovém obybu a měření hmotnosti. Chemické složení oxidické vrstvy bylo vyhodnoceno pomocí EDS. Žádná z vrstev s nebo bez žíhání neprokázaly zlepšení oxidických vlastností. Vyšší teplota žíhání prokýzala zlepšení mechanických vlastnotí vrstvy, ale zhoršení materiálu.
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Design and Operation of Water Disinfections Plants
Krupicová, Simona ; Rajnochová, Markéta (referee) ; Kučera, Tomáš (advisor)
In the first part of my bachelor thesis I deal with individual disinfectants used for hygienic supply of drinking water based on chlorine and without chlorine. Then I mention the operation without chlorine disinfectants. In the second part of this thesis I describe individual plants using various disinfection methods and at the end of the thesis I compare these methods and use it in practice.
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Bulk materials from oxidized powder feedstock
Luptáková, Diana ; Molliková, Eva (referee) ; Jan, Vít (advisor)
In this thesis, methods of effective aluminium powder oxidation are evaluated, such as oxidation at higher temperatures in atmosphere, anodic oxidation and oxidation during high-energy ball milling. It describes following treatment and methods creating volume sammples in such way, where ductile properties are preserved, but the process of hardening by aluminium oxide occurs.
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The problems of fenol sorption from waste water
Židek, Michal ; Pavlovský,, Jiří (referee) ; Doležalová Weissmannová, Helena (advisor)
The bachelor work deals of sorption of phenol from waste water. In theoretical part the basic characteristic of phenol, their effects and presence in environmental compounds are described. The possibility of removal phenol from waste water in waste water treatment is also described. The adsorption process of removal phenol introduced too. The analysis current adsorbents using in removal phenol from aqueous solutions and characteristic properties are also presented in relation to materials on the base of clay minerals. The experimental part is focused on the possibility of removal phenol from aqueous solution via adsorption mechanism under various pH conditions.
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Selective hydrogenation/Oxidation of CVD graphene using AFM
Přikryl, Vojtěch ; Švarc, Vojtěch (referee) ; Bartošík, Miroslav (advisor)
Graphene is a perspective material for utilization in electronics due to its high charge carrier mobility. However, in order to be applicable in practice the bandgap opening is necessary. One way of achieving this is modification of graphene by hydrogenation or oxidation. This work concerns the possibility of using AFM for local hydrogenation/oxidation of graphene depending on the bias voltage between the tip and the sample. The presence of hydrogenation/oxidation was examined by Kelvin probe force microscopy and Raman spectroscopy. The possibility of oxidation was proved but hydrogenation was not proved.
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