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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 biochemical parameters of wine and their changes during ageing
Vacková, Tereza ; Hudeček, Jiří (advisor) ; Hodek, Petr (referee)
3. Abstract Wines marketed under the same brandname and designation may differ in color and other characteristic, as they may come from different batches. These differences may reflect different concentrations of individual components in wine, reflecting, for example, different compositions of individual cupages. We used the reagent set "Malá vinařská laboratoř" (supplied by the BS Vinařské závody, Velké Bílovice, ČR) to determine principal parameters of two samples of a white wine with the same brandname, differing in color. For comparison, one sample of red wine was studied with the same methods. After opening the wine, we followed the changes of selected parameters during ageing, for 14 days (keeping the wine in a cold place), and also in a short-term experiment under elevated temperature. Our laboratory data were complemented by a more detailed analysis of phenolics and other antioxidants, performed in a specialised laboratory (Mendel Agricultural University, Brno, ČR).
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Factors influencing electrochemical oxidation of m-cresol at boron-doped diamond electrode
Procházková, Kateřina ; Schwarzová, Karolina (advisor) ; Vyskočil, Vlastimil (referee)
This study investigates electrochemical oxidation of m-cresol on boron-doped diamond electrode using direct current voltammetry (DCV), differential pulse voltametry (DPV) and cyclic voltammetry (CV). In aqueous media in pH range 2.0 - 12.0 m-cresol provides one oxidation peak. The electrode reaction is diffusion-controled. Because of electrode passivation two types of pretreatment were applied for reactivation of electrode surface., i.e. alumina polishing and anodic activation using potential of +2400 mV. Peak heights and potentials are strongly dipending on the type of pretreatment for DCV and DPV - the difference in peak potentials can reach 430 mV. Using optimal conditions for alumina polishing in 0.01 μmol·L-1 NaOH the linear dynamic range is 1.0 - 75 μmol·L-1 for DCV and 0.75 - 75 μmol·L-1 for DPV. And for anodic activation in BR buffer pH 2.0 the linear dynamic range is 0.75 - 75 μmol·L-1 for DCV and DPV. The influence of boron-doping level was investigated using a semiconductive and mettalic-type BDD film. For the latter the sensitivity in DP voltammetry is two times higer and for both types the linear dynamic range is ca 1 - 25 μmol·L-1 . The voltammetric response of m-cresol was further investigated in the presence of cationic surfactants. In the presence of CTAB and CPB the peak current...
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Voltammetric detection of stigmasterol at boron-doped diamond electrode in mixed media
Benešová, Lenka ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
V o l t a m m e t r i c d e t e c t i o n o f s t i g m a s t e r o l a t b o r o n d o p e d d i a m o n d e l e c t r o d e i n m i x e d m e d i a L e n k a B e n e š o v á Univerzita Karlova v Praze Přírodovědecká fakulta Praha 2015 Abstract The aims of the study thesis was to suggest suitable solvent for oxidation of stigmasterol on boron doped diamond electrode. Cyclic voltammetry in mixed media of water and organic solvents was used for this purpose. First of all, the effect of organic solvent on potential window of boron doped diamond electrode was studied. Solvents used were methanole, isopropanole, N-dimethylformamide and acetonitrile; the water components was phosphate buffer (0,075 mol.l-1, pH 3,0). It was deduced from the results, that suitable solvent for detection of stigmasterol on was the acetonitrile, which provided sufficiently large potential window in anodic area. Keywords: boron doped diamond electrode, cyclic voltammetry, organic solvent, oxidation, stigmasterol
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Biochemical aspects of study and restoration of aged paintings
Hradilová, Iveta ; Hudeček, Jiří (advisor) ; Smrček, Stanislav (referee)
Every part of a work of art is changing in the course of time. Even simultaneously in its creation, when tempera or oil paint used dry up. Already this process can be considered as a biochemical change in the material. The main goal of a submitted bachelor's thesis is to compile recent knowledge about resins and protein media used in works of art, to describe their composition and, in particular to evaluate the changes they undergo in time after their application on canvas, wooden or metal surfaces and paper to their irrecoverable destruction. In addition, biological degradation of these substances by several species of bacteria, yeasts and fungi is discussed in the last part of this work. Key words: resins, terpenoids, protein media, degradation, oxidation, hydrolysis (In Czech)
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Physically chemical properties of epitaxial films CeO2/Cu(110)
Aulická, Marie ; Veltruská, Kateřina (advisor) ; Nehasil, Václav (referee)
In this work ways of preparation of thin epitaxial cerium oxide film on Cu(110) surface were studied. X-ray photoelectron spectroscopy (XPS), X-ray photoelectron difraction (XPD), low energy electron difraction (LEED), ion scattering spectroscopy (ISS) and scanning tunneling microscopy (STM) were used for the characterization of prepared systems. The island structure of CeO2 was prepared by the method of reactive evaporation in oxygen atmosphere. The influence of temperature on the electronic structure and morphology was studied. At the temperature above 550 ˚C partial reduction to Ce2O3 and reordering of the islands to the CeO2(331) structure was observed. The ceria promoted oxidation of copper surface was approved, since the clean c(6x2) reconstruction of the surface was observed at the oxygen exposure 1,5 order of magnitude lower then on Cu(110) alone. The other model system was prepared by cerium evaporation to the oxygen precovered Cu(110) surface. The mix of (2x1) and c(6x2) surface reconstruction was formed by oxygen exposition at 300 ˚C. Cerium was deposited on this surface, also at 300 ˚C. During the following heating to 500 ˚C the formation of epitaxial film Ce2O3(0001) was observed, accompanied by the formation of large hundreds nm long smooth band structures in the [11̄0] direction.
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Metabolism of cabozantinib by enzymes of first phase of biotransformation
Jurečka, Tomáš ; Indra, Radek (advisor) ; Kubíčková, Božena (referee)
Cabozantinib is an anticancer drug that inhibit tyrosine kinases which allow signal pathways important for growth and development of tumors. It is used for treatment of medullary thyroid cancer, hepatocellular carcinoma and kidney cancer. The major enzymes of the first phase of biotransformation that metabolize cabozantinib are cytochromes P450. In this thesis it was studied metabolism of cabozantinib and cytochromes P450 that participated on this metabolism. Hepatic microsomes of rat, mouse and rabbit were used for studying metabolism of cabozantinib in this thesis. It was also focused on the impact of particular isoforms of cytochromes P450 on metabolism of cabozantinib in rat microsomes. Time dependence of cabozantinib conversion in hepatic rat microsomes was also studied. Enzyme kinetics of metabolism of cabozantinib in hepatic rat microsomes, as well as impact of cytochromes P450 inhibitors on the metabolism were included. Metabolites were analyzed by high performance liquid chromatography (HPLC) and mass spectrometry. Formation of metabolites of cabozantinib increased over time to 30 minutes of incubation and with some others to 40 minutes of incubation. Up to five different metabolites were detected in experiments (M1, desmethyl cabozantinib, M3, monohydroxy cabozantinib and cabozantinib...
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The influence of the surface pretreatment of boron doped diamond electrodes on electrochemical oxidation of phenol and its derivatives
Hnízdilová, Lucie ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis is the study of electrochemical oxidation of para-substituted phenol derivates using cyclic voltammetry (CV) and ,,direct current" voltammetry (DCV) on boron-doped diamond electrode (BDD) and comparison with some analogous meta-substituted compounds. Among the studied substances were p-cresol, 4-methoxyphenol, 4-hydroxybenzoic acid, 3-(4-hydroxyphenyl)propionic acid, 4-nitrophenol, 4-chlorophenol and 3-(trifluoromethyl)phenol. The oxidation of the analytes was performed in an acidic (pH 2,0) and basic (pH 11,0) Britton-Robinson buffer on mechanically polished, oxidated and hydrogenated surfaces. Another subject of the thesis is to analyze the influence of different substituents, characterized by the Hammett constant, on the oxidation potential of selected phenols. They are oxidized at more positive redox potentials in acidic media, than in basic media, where they are dissociated. The oxidation on the polished and hydrogenated surfaces were similar, whereas were shifted to higher values on the oxidated surface. Further, the signal intensity decreased on the oxidated one, and the oxidation of phenols was not recognizable in basic media. The passivation of the electrode was less significant in pH 2,0 buffer. The best result of Hammett correlation was achieved on a polished and...
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Biodegradable bones implants based on iron
Hrabovský, Jan ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This work deals with a current topic, which are biodegradable bone implants. These implants seem to be a suitable candidate for temporary fixations, with their gradual decomposition. An important parameter is not only the mechanical properties so that the material can withstand the load, but above all the corrosion properties and the degradation process. This work introduces the physiology of bone, trace elements and also describes current trends in the field of implants. The last part is a theoretical introduction to cross-stage processes. The practical part is focused on the preparation of iron-based samples with various dopants, subsequent annealing and analysis.
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