|
Comicellization of polystyrene-block-poly(acrylic acid) with low-molar-mass surfactants
Paloncýová, Markéta ; Matějíček, Pavel (referee) ; Štěpánek, Miroslav (advisor)
This B.Sc. thesis deals with the study of the effect of low-molar-mass ionic surfactants sodium dodecyl sulfate (SDS) and hexydecyltrimethylammonium bromide (HTAB) on association behavior of the block copolymer polystyrene-b-polyacrylic acid (PS-b-PAA) in alkaline aqueous solutions. Prepared polymeric nanoparticles were characterized by static and dynamic light scattering, transmission electron microscopy and 1 H NMR spectroscopy. It was found that both surfactants interact only with PAA blocks and their presence in the system leads to worsening of the copolymer solubility which manifests itself in the formation of large micellar aggregates and in precipitation of the copolymer-surfactant complexes.
|
|
Kompozity na bázi silikalit-1- polyimidy
Šnáblová-Fryčová, M. ; Sysel, P. ; Chánová, E. ; Bernauer, B. ; Kočiřík, Milan
Two methods of adhesion improvement between the polyimide matrix and zeolite (silicalite-1) were examined. Firstly, there were prepared polyimide precursors (polyamic acids) with controlled molecular weight terminated with 3-aminopropyltriethoxysilane. The transformation of polyamic acids into polyimides upon heating was accompanied by the formation of Si-O-Si bonds between the polymeric matrix and hydroxyl groups on zeolite surface. Secondly, the polyimide was modified using rubbery poly(dimethylsiloxane)s. Relations between film properties (i.e. interfacial adhesion and accessibility of zeolite channels for species) and film composition were studied both for unfilled and filled PI films.
|
|
Mikroorganismy s dekarboxylázovou aktivitou z mléka a mléčných výrobků
Hůlová, Michaela
This thesis deals with bacteria that are capable decarboxylase one or more amino acids and thus contribute to the formation of biogenic amines. The aim of this work was to characterize the bacteria with decarboxylase activitthe Escherichia coli, Bacillus, Lactobacillus, Enterococcus isolated from milk and dairy products. Microorganisms were inoculated into tubes with diagnostic medium. To test was used seven amino acids. Incubation tubes conducted at 6, 25, 30 and 37 ° C for 10 days during which the color change was monitored. The tested isolates of Escherichia coli were detected decarboxylase activity, especially for tyrosine and ornithine. The bacterium Bacillus licheniformis was found decarboxylase activity, especially on tyrosine. The bacteria Lactobacillus isolates tested were shown the strongest decarboxylase activity especially for arginine. The bacteria Enterococcus was demonstrated the strongest decarboxylase activity especially for arginine. Furthermore, the observed production of carbon dioxide and formation of biogenic amines contaminating microorganisms in cow's and goat's curd.
|
| |
|
Význam glutathionu pro kvalitu hroznů a vína
Kandourova, Alexandra
Glutathione is an important constituent of grape, must, and wine. Special emphasis is given to its occurrence in grapes, must, and wine; its role as an antioxidant in wine. The effect of glutathione on aroma compounds is also outlined. There are information on the positive effects of the use of glutathione-enriched preparations in wine industry. It is evaluated its effectiveness in combination with ascorbic acid against oxidative color formation.
|
|
Durability of alkali-activated systems
Šafář, Martin ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Alkali activated binders have the potential to become an alternative construction material to ordinary portland cement binders. This thesis concentrates on durability testing of alkali activated blast furnace slag and fly ash based concrete. The chosen aspects of durability included sulfate resistance, acid resistance, carbonation, freeze-thaw resistance, frost-salt resistance and porosity. Microstructural changes and formation of new crystalline phases were observed using XRD and SEM-EDX analysis. Potential application of the tested material from the durability point of view was evaluated by comparison with a reference ordinary portland cement based concrete.
|
|
Photoelectrochemical oxidation of aqueous polutants
Pachovská, Martina ; Králová, Marcela (referee) ; Dzik, Petr (advisor)
The thesis is focused on the use of photochemical reactions and their applications for removal of aqueous pollutants such as organic acids. For evaluation of photochemical oxidation was used benzoic acid as model pollutant. Decreasing of concentration and oxidation products were monitored by UV-VIS spectrometry. The formation of oxidation products was observed by fluorescence measurement. Subsequently the stability and properties of model aqueous pollutant and electrochemical properties of used photoelectric cells were studied. The aim was to determine the appropriate reaction conditions and limits of degradation reaction.
|
|
The Role of Uncoupling in Down-regulation of Reactive Oxygen Species
Ježek, Jan ; Žáčková, Markéta (advisor) ; Modrianský, Martin (referee) ; Drahota, Zdeněk (referee)
Uncoupling attenuates Complex I-derived superoxide production by accelerating electron flux and proton pumping within Complex I. However, under circumstances leading to hampered proton pumping pathway within Complex I, e.g. due to aberrant mutations of mtDNA encoding either ND2, ND4 or ND5 Complex I H+-pumping subunit, therapeutic strategy based simply on uncoupling would fail. Experimentally, hydrophobic amiloride EIPA mimicks the model of disabled H+-pumping. We show for the first time that EIPA is a real inhibitor of H+-pumping of mitochondrial Complex I. We searched for an agent that, unlike uncoupling, would be able to counteract oxidative stress associated with obstructed proton pumping of Complex I. Mitochondria-targeted ubiquinone MitoQ10 proved to be an effective antioxidant for this purpose when the rate of superoxide formation was high due to the electron flow retardation within Complex I. Because of its pro-oxidant properties, targeted delivery of MitoQ10 as a cure to the pathological tissue is necessary. Activation of mitochondrial phospholipase iPLA2 by mild oxidative stress can provide free fatty acid hydroperoxides as the cycling substrates for UCP2 that initiates mild uncoupling leading to the attenuation of reactive oxygen species (ROS) production, as a part of feedback regulatory loop of...
|
|
Durability of alkali-activated materials
Zourek, Milan ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This bachelor’s thesis deals with durability of alkali-activated materials and the use of them in aggressive surroundings, especially in sewer systems. The first half of the theoretical part summarizes requirements for concrete sewer pipes. The most common linings and coatings used in concrete sewer systems are mentioned. The second half of the theoretical part deals with alkali-activated materials, raw materials used for their preparation and their durability. Concretely sulfate attack resistance, chloride attack resistance, acid attack resistance, abrasion, porosity, freeze-thaw resistance, thin layer applications and cracking tendency. In the experimental part of this bachelor’s thesis there were proposed five types of alkali-activated materials application in the aggressive environment of sewer systems. Density and consumption of alkali-activated material by thin layer application was determined as fresh properties. Material was monitored during its solidifying and hardening, especially for crack formation. As hardened properties density, flexural strength, compressive strength, adhesion of thin layer to concrete, thickness of thin layer, freeze-thaw resistance, resistance of surface to water and defrosting chemicals were determined.
|
|
Transition metal catalyzed cross-coupling reactions of onium salts
Hidasová, Denisa ; Šrogl, Jiří (advisor) ; Drahoňovský, Dušan (referee)
The research of this thesis is focused on developing Suzuki cross-coupling reactions of various onium salts using the catalytic system Ni complex/trans-N,N'-dimethyl-1,2- cyklohexanediamine. As an expansion in the catalysis of nickel compounds, we have established that the catalytic system Ni(cod)2/trans-N,N'-dimethyl-1,2-cyklohexanediamine can affect Suzuki reactions of tetramethylenesulfonium salts with boronic acid, which leads to cleavage of C-S and formation of new C-C bonds under relatively mild reaction conditions. This explains the unique reactivity and biomimetic behavior of a nickel catalyst to activate the C-S bond. Key words: onium salts, Suzuki coupling, nickel complexes
|
guest ::
