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Dating of radioactive mineral springs of the Krkonoše-Jizera crystalline by 230Th/234U method
Fanta, Martin ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
The isotopes 238 U, 234 U and 230 Th, as members of the uranium-radium decay chain, are fractionated in the environment by changes of geochemical conditions, and they can be used for dating of recent or past geochemical processes in the Quaternary. Samples of water with uranium and of water-activated solids were taken of radioactive mineral water springs at two study sites in the area of Krkonoše-Jizera crystalline complex: Svatý Vojtěch (St. Adalbert) in Horní Malá Úpa, and Bukový Pramen in the Těsný důl valley in Janské Lázně. Uranium was co-precipitated in field conditions with hydroxides of FeIII+ in 50-liter water samples of the radioactive springs. In the lab, uranium and thorium were separated from water precipitates, as well as from solid samples after their chemical decomposition, using chromatographic extraction agent UTEVA. All the three isotopes of interest emit alpha particles, and so their activities were measured by alpha spectrometry and expressed as 234 U/238 U and 230 Th/234 U ratios. As an internal standard, 232 U/228 Th was used. The resulting 234 U/238 U activity ratios of four water samples measured ranged from 1.0747 to 1.423. In twelve samples of solid phases activity ratios 234 U/238 U from 0.861 to 1.129 were determined. The 230 Th/234 U activity ratios form two distinct...
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Determination of the age of secondary uranium minerals using 230Th/234U in selected localities of the Bohemian massif
Roll, Michal ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
This thesis is focused on prominent uranium deposits in Czech Republic and their secondary uranium mineralization. Main goal of this thesis is to analyze collected minerals and to determine their ages. Next step is to prove or disprove hypothesis that this secondary uranium minerals are products of Quaternary glacier weathering. As a suitable analytical method, an alpha spectrometry was used and the age was calculated by 230 Th/234 U ratio. Firstly, chosen methodology was verified with admixture of reference material PU1 (Přibram uraninite) in secular equilibrium and internal standard, both with known activity. Analyzed spectra confirmed that some of the samples lay on the very edge of datability, especially in case of PL1 and GF1, both samples are very young, so they easily could be products of anthropogenic activity (changed environment due to mining works). On the other hand, in case of sample GF3, the age was successfully determined, although it is also quite young phase. In case of samples ME3, ME4 and ME6 was used threshold dating method, because they were considered to be too old for age calculation. The rest of the samples chosen for age determination was analyzed without further complications. Based on the age and geological setting, samples GF3 (3 725 ± 845 years), JE1 (10 655 ± 1 795...
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Dating of radioactive mineral springs of the Krkonoše-Jizera crystalline by 230Th/234U method
Fanta, Martin ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
The isotopes 238 U, 234 U and 230 Th, as members of the uranium-radium decay chain, are fractionated in the environment by changes of geochemical conditions, and they can be used for dating of recent or past geochemical processes in the Quaternary. Samples of water with uranium and of water-activated solids were taken of radioactive mineral water springs at two study sites in the area of Krkonoše-Jizera crystalline complex: Svatý Vojtěch (St. Adalbert) in Horní Malá Úpa, and Bukový Pramen in the Těsný důl valley in Janské Lázně. Uranium was co-precipitated in field conditions with hydroxides of FeIII+ in 50-liter water samples of the radioactive springs. In the lab, uranium and thorium were separated from water precipitates, as well as from solid samples after their chemical decomposition, using chromatographic extraction agent UTEVA. All the three isotopes of interest emit alpha particles, and so their activities were measured by alpha spectrometry and expressed as 234 U/238 U and 230 Th/234 U ratios. As an internal standard, 232 U/228 Th was used. The resulting 234 U/238 U activity ratios of four water samples measured ranged from 1.0747 to 1.423. In twelve samples of solid phases activity ratios 234 U/238 U from 0.861 to 1.129 were determined. The 230 Th/234 U activity ratios form two distinct...
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Dynamic Maintenance of Entities
Mizera, Jiří ; Richta, Karel (advisor) ; Yaghob, Jakub (referee)
Title: Dynamic Maintenance of Entities Author: Jiří Mizera Department: The Department of Software Engineering Supervisor: doc. Ing. Karel Richta CSc. Supervisor's e-mail address: richta@ksi.mff.cuni.cz Abstract: The aim of my master thesis is to create a tool for dynamical administration of entities and modules. Common application consists of modules operating with certain data. The user experience shows the need of changing the data structure or changing and adding the modules. Propose a solution which enables such dynamical administration and demonstrate it on the prototype. This system should generate fields for inputing, editing or deleting new entries automatically, also including control of individual attributes. At the same time the system considers also losing saved data and the possibility of data transformation to the new version of the system. Keywords: entity, maintenance, module, data
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