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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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Biotransformation of phenols by enzymatic systems of Candida tropicalis yeast and Comamonas testosteroni bacteria
Vilímková, Lenka ; Stiborová, Marie (advisor) ; Entlicher, Gustav (referee) ; Mareš, Jaroslav (referee)
Candida tropicalis yeast and bacteria Comamonas testosteroni have been considered to be able to metabolize phenol and utilize it as the only source of carbon and energy. In our laboratory we investigated the cytoplasmic enzymes responsible for the first and second step of phenol degradation, NADPH-dependent phenol hydroxylase of both C. tropicalis and C. testosteroni and catechol 1,2-dioxygenase of C. tropicalis. The aim of our study was to isolate and partially characterize those enzymes. Phenol hydroxylase purification consisted of preparation of cytosol from C. tropicalis yeast by fraction centrifugation, chromatography and re-chromatography on a column of DEAE Sepharose, fractionation by precipitation of the enzyme with polyethylene glycol 6000 and gel permeation chromatography on a column of Sephacryl S-300. Extracellular phenol hydroxylase of C. testosteroni was purified by fraction precipitation with polyethylene glycol 6000 and by gel permeation chromatography on 4B Sepharose and Sephacryl S-300. Catechol 1,2-dioxygenase was purified using the procedure consisting of: chromatography and re- chromatography on a column of DEAE Sepharose, lyophilization of the enzyme and gel permeation chromatography on a column of Sephadex G-100. The enzyme activity was determined by two methods: use of HPLC...
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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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Phosphinoferrocene conjugates of selected amino acids
Tauchman, Jiří ; Štěpnička, Petr (advisor) ; Růžička, Aleš (referee) ; Dvořák, Dalimil (referee)
A series of chiral phosphinoferrocene amides was prepared by the condensation either of 1'- (diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) or its planar-chiral 1,2-isomers and amino acid methyl esters in the presence of peptide coupling agents. The resulting phosphinoamides were tested as ligands in Cu-catalyzed asymmetric conjugate additions of diethylzinc to chalcones and in Pd-mediated asymmetric allylic substitution reactions of 1,3- diphenylallyl acetate with the respective nucleophile (alkylation, amination and etherification). The catalytic tests were focused on an optimization of the reaction parameters (solvent, temperature, base, metal/ligand ratio) and on survey of various substrates. Compounds based on Hdpf proved to be better ligands in both catalytic reactions than their planar chiral analogues. In order to rationalize the influence of the ligand structure on the reaction course and also to interpret the catalytic results, several model complexes were prepared and structurally characterized. Other three series of non-chiral complexes were prepared from the corresponding (η6 - arene)ruthenium(II) precursor and Hdpf-glycine conjugates; the neutral complexes of the type [(arene)RuCl2(Hdpf-Gly(R)-κP)] (arene = benzene, p-cymene, hexamethyl-benzene; R = OMe, NH2, OH) as well as two...
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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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The comparison of the efficiency of cytochromes P450 expressed in prokaryotic and eukaryotic systems
Kroftová, Natálie ; Stiborová, Marie (advisor) ; Martínková, Markéta (referee)
v anglickém jazyce Cancer disease is a group of clinically diverse diseases characterized by uncontrolled proliferation of cancer cells incapable of differentiation. Tumor therapy consists of a combination of surgery, radiotherapy and chemotherapy utilizing cytostatic agents. The plant alkaloid ellipticine ranks among a group of cytostatic agents. Its mode of action is based on DNA intercalation, inhibition of topoisomerase II and formation of covalent DNA adducts. Ellipticine is oxidized through cytochromes P450 catalysis into detoxication metabolites 9-hydroxyellipticine and 7-hydroxyellipticine, and into activation metabolites 12-hydroxyellipticine, 13-hydroxyellipticine and ellipticine N2 -oxide. The aim of practical part of this work was to compare the efficiency of human cytochromes P450 1A1/2 and 3A4 expressed in prokaryotic and eukaryotic systems in the process of ellipticine oxidation. Ellipticine metabolites were analysed using high performance liquid chromatography. It was found that cytochrome P450 1A1 expressed in the prokaryotic system catalyses predominantly the formation of 9-hydroxyellipticine and 7-hydroxy- ellipticine. The difference is minimal in the production of ellipticine metabolites catalysed by cytochromes P450 1A2 expressed in both cellular systems. The formation of...
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Study of influence of the substrate temperature on the structure of epitaxial tungsten oxide layers
Pavlíková, Romana ; Mašek, Karel (advisor) ; Veltruská, Kateřina (referee)
Purpose of this thesis is a study of substrate temperature influence on structure, chemical composition and morphology of tungsten oxide thin films prepared by oxidation of a tungsten single crystal W(110) using a radio frequency plasma source. Thin film's parameters were observed by RHEED, XPS, AFM snad SEM. The substrate was oxidized at room temperature (RT) and at temperatures of 400ř C, 500ř C and 550ř C. In the first and the second case, produced thin films were amorphous and epitaxial structure was obtained by recrystallization. At the temperature of 500ř C, an epitaxial thin film was produced directly. After further heating at the temperature of 550ř C we got polycrystalline thin film without orientation of the crystal grains. All the epitaxial thin films had (111) crystallographic plane parallel to substrate surface. The tungsten oxide layers grew with relatively hight surface roughness in the order of several nanometers.
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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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