|
|
Speciace rtuti v rybích tkáních
Hrůzová, Marie
The diploma thesis is focused on the issue of contamination of freshwater fish species by chemical forms (species) of mercury. To monitor mercury speciation in fish tissues, four locations in the Czech Republic were selected - the Záskalská reservoir, Rybníkářství Pohořelice a.s., the Smrk pond, and the Lipolec pond. The Záskalská reservoir is located near the historic cinnabar mine, hence an increased risk of fish contamination was expected. No significant source of mercury contamination was identified in the other aquatic ecosystems. Four fish species - perch (Perca fluviatilis), roach (Rutilus rutilus), pike (Esox lucius), and European eel (Anguilla anguilla) were caught for analysis. Fish tissue samples (muscles, gills, liver, and skin) were analyzed for total mercury concentrations using atomic absorption spectrometry on an AMA 254 and for individual mercury species using High-performance liquid chromatography with atomic fluorescence detection (HPLC-CV-AFS). The highest total mercury contents were found in the muscles of fish from the contaminated Záskalská reservoir. The muscle tissues of pike, perch, and roach from the Záskalská reservoir exceeded the limit set by Regulation No. 1881/2006 EC. Only inorganic mercury species (Hg2+) and methylmercury species (MeHg+) were found in fish tissues. The highest amounts of methylmercury were found in muscle tissues (63-96 %), followed by skin (55-90 %), liver (31- 82 %), and gills (42-81 %). Statistically significant differences in mercury species content were compared between predatory and non-predatory fish, contaminated and non-contaminated locations, and the thesis also assessed the impact of age, species, and diet on the speciation of mercury in fish tissues.
|
|
|
Thermal conductivity measurements of materials for the MaMBA project
Sviták, David ; Vališka, Michal (advisor) ; Hrůzová Kratochvílová, Marie (referee)
The content of this work is the measurement of thermal conductivity of materials within the MaMBA project. Single crystalline samples of LaNi$_5$ and PrNi$_5$ were successfully oriented along $a$ and $c$ axis each and disc-shaped polymer samples of PETG and PLA were 3D printed. Thermal conductivity was measured on these samples. The thermal conductivity electrical resistivity and Seebeck coefficient were measured on the intermetallic compounds in the temperature range 2-390K. A magnetoelastic interaction was observed in the PrNi$_5$ samples, contributing to the thermal conductivity. The magnetic character of the PrNi$_5$ compound also contributes to the resistivity at temperatures below 50K. This magnetic contribution was determined for both $a$ and $c$ axis. Finally, the temperature dependence of the thermal conductivity of PETG discs was measured in the temperature range 3-300K. The thermal conductivity of the PLA discs was measured at room temperature.
|
|
|
Magnetic study of layered tetragonal compounds based on rare earths and uranium
Bartha, Attila ; Hrůzová Kratochvílová, Marie (advisor)
We have studied the interplay between the layered crystal structure and the 5f magnetism in uranium-based tetragonal compounds UnTIn3n+2. Sin- gle crystals of U2RhIn8, URhIn5 and UIn3 were prepared by In self-flux method. The novel U2RhIn8 compound adopts the Ho2CoGa8-type struc- ture with lattice parameters a = 4.6056(6) ˚A and c = 11.9911(15) ˚A. The behavior of U2RhIn8 strongly resembles that of related URhIn5 and UIn3 with respect to magnetization, specific heat and electrical resistivity except for magnetocrystalline anisotropy developing on stacking composition in the series UIn3 vs. U2RhIn8 and URhIn5. U2RhIn8 orders antiferromagnetically below TN = 117 K and exhibits slightly enhanced Sommerfeld coefficient γ = 47 mJ·mol−1 ·K−2 . TN increases with increasing c/a ratio in contrast to the behavior of their CenTIn3n+2 counterparts. Magnetic field leaves the value of the Néel temperature of URhIn5 and U2RhIn8 unaffected up to 9 T. On the other hand, TN increases with applied hydrostatic pressure up to 3.2 GPa with the ∂TN/∂p coefficient resembling URhIn5 and UIn3. Ther- mal expansion of U2RhIn8 reveals a hysteretic behavior of the antiferromag- netic transition pointing to its 1st -order character. The magnetic structure of URhIn5 obtained from neutron diffraction propagates with k = (1 /2, 1 /2, 1 /2) and the...
|
|
|
Magnetic study of layered tetragonal compounds based on rare earths and uranium
Bartha, Attila ; Hrůzová Kratochvílová, Marie (advisor)
We have studied the interplay between the layered crystal structure and the 5f magnetism in uranium-based tetragonal compounds UnTIn3n+2. Sin- gle crystals of U2RhIn8, URhIn5 and UIn3 were prepared by In self-flux method. The novel U2RhIn8 compound adopts the Ho2CoGa8-type struc- ture with lattice parameters a = 4.6056(6) ˚A and c = 11.9911(15) ˚A. The behavior of U2RhIn8 strongly resembles that of related URhIn5 and UIn3 with respect to magnetization, specific heat and electrical resistivity except for magnetocrystalline anisotropy developing on stacking composition in the series UIn3 vs. U2RhIn8 and URhIn5. U2RhIn8 orders antiferromagnetically below TN = 117 K and exhibits slightly enhanced Sommerfeld coefficient γ = 47 mJ·mol−1 ·K−2 . TN increases with increasing c/a ratio in contrast to the behavior of their CenTIn3n+2 counterparts. Magnetic field leaves the value of the Néel temperature of URhIn5 and U2RhIn8 unaffected up to 9 T. On the other hand, TN increases with applied hydrostatic pressure up to 3.2 GPa with the ∂TN/∂p coefficient resembling URhIn5 and UIn3. Ther- mal expansion of U2RhIn8 reveals a hysteretic behavior of the antiferromag- netic transition pointing to its 1st -order character. The magnetic structure of URhIn5 obtained from neutron diffraction propagates with k = (1 /2, 1 /2, 1 /2) and the...
|
|
|
Studium magnetismu vrstevnatých tetragonálních sloučenin na bázi vzácných zemin a uranu
Bartha, Attila ; Hrůzová Kratochvílová, Marie (advisor) ; Prokleška, Jan (referee)
We have studied the interplay between the layered crystal structure and the 5f magnetism in uranium-based tetragonal compounds UnTIn3n+2. Sin- gle crystals of U2RhIn8, URhIn5 and UIn3 were prepared by In self-flux method. The novel U2RhIn8 compound adopts the Ho2CoGa8-type struc- ture with lattice parameters a = 4.6056(6) ˚A and c = 11.9911(15) ˚A. The behavior of U2RhIn8 strongly resembles that of related URhIn5 and UIn3 with respect to magnetization, specific heat and electrical resistivity except for magnetocrystalline anisotropy developing on stacking composition in the series UIn3 vs. U2RhIn8 and URhIn5. U2RhIn8 orders antiferromagnetically below TN = 117 K and exhibits slightly enhanced Sommerfeld coefficient γ = 47 mJ·mol−1 ·K−2 . TN increases with increasing c/a ratio in contrast to the behavior of their CenTIn3n+2 counterparts. Magnetic field leaves the value of the Néel temperature of URhIn5 and U2RhIn8 unaffected up to 9 T. On the other hand, TN increases with applied hydrostatic pressure up to 3.2 GPa with the ∂TN/∂p coefficient resembling URhIn5 and UIn3. Ther- mal expansion of U2RhIn8 reveals a hysteretic behavior of the antiferromag- netic transition pointing to its 1st -order character. The magnetic structure of URhIn5 obtained from neutron diffraction propagates with k = (1 /2, 1 /2, 1 /2) and the...
|
guest ::
RSS feed.