Catalysts based on cerium oxide are ubiquitous in industrial-scale chemical conversion. Here, a thorough study of their fundamental properties is undertaken via a model system ap- proach with the goal of furthering rational design in heterogeneous catalysis. A focus is put on understanding the behavior of oxygen vacancies in cerium oxide with respect to atomic co-ordination and electronic structure perturbations. Utilizing state-of-the-art probing tech- niques, a scalable model system framework is developed that allows for control over both the oxygen vacancy concentration and local co-ordination. High precision of the innova- tive approach facilitated observation of new phases of substoichiometric cerium oxide and lead to a first-of-a-kind investigation of the electronic structure of cerium oxide throughout isostructural transition from CeO2 to Ce2O3. The acquired results advance fundamental understanding of essential properties of cerium oxide that are relevant to its utilization in heterogeneous catalysis and open new pathways for functionalization of cerium oxide-based materials. Furthermore, the methodology developed in the thesis is transferable to other important reducible oxides. 1

Nowadays, there is an increasing risk of bacterial infections from bacteria strains resistant towards antibiotics. Thus, it is of utmost importance to research novel therapies which can overcome this difficulty. The presented thesis focuses on the preparation, characterization and antibacterial evaluation of polystyrene polymer nanomaterials (nanofiber membranes and nanoparticles) modified with compounds that can efficiently inhibit bacterial growth either by their nature (polyethyleneimine) or by photoactivation upon visible light excitation (NO- photodonors, photosensitizers) and consequent production of highly reactive inorganic bactericidal species, nitric oxide (NO) and singlet oxygen (O2(1 g)). All materials were fully characterized by several independent methods. The concentrations of NO and O2(1 g) were measured by amperometric and time-resolved spectroscopic techniques and by variety of chemical analytic procedures. Due to the presence of bactericidal species and the efficient photogeneration of NO and O2(1 g) at physiological conditions, all materials exhibit strong antibacterial action tested on a Gram-negative bacterial strain Escherichia coli. Hence, these functionalized polymer nanomaterials may be intriguing systems for medical-, biological-, or environmental- application where a...

Nitric oxide (NO) has been proved to reduce parasite burden in vertebrates infected with Schistosoma, Fasciola, Brugia or Taenia. NO negatively influences parasite growth and development, which then leads to smaller parasite-caused damage to the liver during schistosomosis and stimulates healing processes in muscles infected with Toxocara canis. Peroxynitrite, formed from NO and superoxide, significantly reduces the viability of F. hepatica adults. In case of T. regenti, the neuropathogenic schistosome, the cells capable of NO production (macrophages, neutrophils, eosinophils, microglia and astrocytes) migrate to the site of the infection suggesting that NO might affect T. regenti infection as well. Therefore, the production of NO and its effect on the course of the infection was examined in vivo and the effect of peroxynitrite on T. regenti schistosomula was examined in vitro to assess the role of reactive nitrogen species during the infection. Our results from in vivo experiments demonstrate that although the infection did not significantly elevate nitrite/nitrate results in the sera, NO is locally produced in the early stages of the infection in both the skin and the spinal cord as shown by immunohistochemical detection of inducible NO synthase. Diminishing NO production by aminoguanidine...

Efforts to reduce sulphur dioxide in wine have been the subject of wine interest for several years. Research over recent years has shown the effectiveness of saturated higher fatty acids as an alcohol fermentation inhibitor, even in the production of wine with higher residual sugar. The principle of the function of C8, C10 and C12 fatty acids is simple. They enter the body yeast, which subsequently change their structure and the cell will become permeable to other substances, and thus is not working - yeast stops working and alcoholic fermentation is stopped. The mixture of higher fatty acids of C8, C10 and C12 in the ratio 2 : 7 : 1 can during application of 10 mg.l-1 reduce the necessary dose of SO2 to several tens mg.l -1. The results show that administration of 10 mg.l-1 of a mixture of higher fatty acids in combination with 30-40 mg.l-1 SO2 is as effective as a dose of 60 mg.l-1 SO2 itself. In addition to the demonstrable effect of stopping alcohol fermentation, the HFA (resp. MCFA) mixture appears to be promising before referral (especially for wines with higher residual sugar).

Wood impregnation is one of the oldest and the most frequently used techniques to protect the wood. This treatment offers a wide range of protection depending on used impregnants (preservatives). Impregnation can make the wood more resistant to decay, less flammable, more dimensionally stable, harder, stronger, more UV stable resistant and many more. Generally, the aims of this thesis is to give a new and modern approaches to already known technologies. The experimental part have been carried out using laboratory vacuum-pressure impregnation plant and many other devices. Almost all treatments and measurement have been done in laboratories of Research centre in Útěchov. The different wood species e.g. European beech (Fagus sylvatica L.) and hybrid poplar (Populus hybrids) have been studied. The patented solution shows the method of the treatment and colouring of wood containing tannins, characterized by impregnation with a product containing iron oxide nanoparticles, in a concentration of 0.4 g/l to 42 g/l, an average particle size in the range of 1 to 100 nm, and a liquid medium. Impregnation can be performed as pressure impregnation, followed by soaking, or the product can be applied by brushing or spraying. This method is an alternative to wood ammonification. The tests (Paper I) shows following results. Both nanoiron and ammonia treatments tested induced darker colouring of oak wood, more intensive darkening was observed in case of the nano-iron treatment. The native oak showed a steep drop in lightness ca 25-50 hours of exposure followed by gradual re-increase during further exposure to the artificial sunlight. The darker surfaces generated by tannin reacting chemically with iron and ammonia evidently faded in the course of light exposure. In case of chromatic parameters a* and b*, the AT (ammonia treatment) oak more or less copied the colour change progress of native oak. On the contrary, the NIT (nanoiron treatment) wood showed a double increase in both parameters. The colour of NIT wood after light exposure was more or less equivalent to the original colour of the ammonium-treated. Distinct reddening of NIT oak may be caused by oxidation of non-precipitated iron particles. The antifungal effects of copper and silver nanoparticles against two wood-rotting fungi were investigated with following results (Paper II). The highest value of retention was observed for pine sapwood (~ 2 kg/m3) for both nanoparticle solutions. The amount of nanoparticles in the wood did not increase proportionally with an increasing concentration, but only 1.5-2 times increase was reached. An average leaching of 15% to 35% was observed for copper nanoparticles, depending on used wood species and concentration. Significantly lower leaching (max. 15 %) was observed for pine sapwood impregnated by silver nanoparticles with a concentration of 3 g/l. The highest antifungal effect (under 5 % of mass loss) against both tested fungi was found for nano-copper treatment at the concentration of 3 g/l. However, this effect of treatment seems to be almost negligible after the leaching test. Therefore, this study aims to present fundamental material properties of wood treated with copper and silver nanoparticles, and provide groundwork for further research (e.g. fixation of substances in the wood structure, etc.). In this study (Paper III), selected physical and mechanical properties, i.e., density profile, bending strength, hardness and moisture absorption were investigated for Lignamon (i), which was obtained from the Czech industrial production. Selected properties were also investigated using steam-densified beech (ii) and native beech (iii) and compared with each other. Densitometry of Lignamon showed a large variability of the density profile compared to the density profile of only densified beech. It is affected by the degree of densification, temperature and moisture gradients, and their relationship to the glass transition of the wood cell wall. Modulus of elasticity, hardness, moisture exclusion and anti-swelling efficiency of Lignamon are enhanced compared to densified beech. The enhanced dimension stability and lower hygroscopicity of Lignamon are probably caused by heat treatment during the process. Further investigation will be carried out with self-produced Lignamon samples. The paper IV deals with the effect of vacuum-pressure impregnation of poplar wood (Populus alba L.) by aqueous solutions of sucrose and sodium chloride on its physical properties. The most satisfying final properties were achieved in impregnation of sucrose with concentration of 6.25 g/100 ml H2O. The retention was 31 kg/m3 (WPG around 8 %). The values of ASE (anti-swelling efficiency) reached to 36 % and MEE (moisture exclusion efficiency) was reduced by 33 %. In Paper V, MW and conventional acetylation of wood was carried out to determine its efficacy on the material properties. Both MW and conventional heating positively affected the selected material properties. The results showed that no significant differences were found between MW and conventional heating; therefore, MW heating can be used as a valid replacement in the acetylation process. MW power of 2 kW and 0.1 m/min conveyor speed were the optimum conditions for MW acetylation. These process parameters resulted in 39.4 % ASE (T) and 35.2 % ASE (R) for beech and 38.0 % ASE (T) and 16.3 % ASE (R) for poplar samples. This work provides insight into the details of wood acetylation using MW heating. The study (Paper VI) aims to evaluate the antifungal activity of extractive compounds obtained with fexIKA accelerate extraction process. Results showed that the extractive compounds obtained from black locust heartwood were able to increase the native durability of European beech from class 5 (i.e. not durable with an average mass loss of 43.6 %) to class 3 (i.e. moderately durable with an average mass loss of 12.7 %). The final Paper VII shows following results. After impregnation with residual liquids and leaching, high amounts of TT (thermal treatment) and HTC (hydrothermal carbonisation) solution were washed out, whereas Pyrolysis liquids stayed with 25 % to 40 % remaining in the wood. Volumetric swelling in 65 % relative humidity at 20 °C was reduced from 6.5 % in untreated poplar to 5 % in impregnated samples with process residues of thermal treatment using 180 °C or 200 °C. The processes using HTC liquids from Miscanthus sp. (Misc.) or Sawdust showed reduction to 3-3.5 % and Pyrolysis liquid treatment to 2.5 %. After exposure to fungi, the mass loss of untreated Beech (30-35 %) and Poplar (40-50 %) was reduced to 2 % in case of Pyrolysis- and 4 % in case of TT-treatment.

The aim of present project was to uncover the effect of pharmacological increase in acute and chronic nitric oxide (NO) production on cardioprotective effect of chronic hypoxia. We studied the effect of NO donor molsidomine on hemodynamic conditions and ischemia - induced myocardium injury. Male Wistar rats were exposed to continual hypoxia in a normobaric chamber (10 % O2, 4 weeks). Rats received molsidomine either chronically (15 mg/kg/day) in drinking water or acutely (10 mg/kg) in saline infused 30 min before ischemia. Control rats were kept under normoxia and treated in a corresponding manner. Adaptation to chronic hypoxia resulted in development of pulmonary hypertension. Chronic treatment with molsidomine slightly reduced these consequences of chronic hypoxia but it had no effect on increased cardiac ischemic tolerance in chronically hypoxic rats. On the other hand acute treatment with molsidomine significantly reduced infarct size and increased the number of arrhythmias in both normoxic and chronically hypoxic animals. In conclusion, our data suggests that acute increase in availability of NO is cardioprotective in both normoxic and chronically hypoxic rats contrary to its chronic increase which seems to have no protective contribution.

Aim of this thesis was to design and prepare polymer-coated monodisperse Fe3O4 nanoparticles as a safe and non-toxic contrast agent for magnetic resonance imaging (MRI) and heat mediator for hyperthermia. Uniform superparamagnetic Fe3O4 nanoparticles were synthesized by thermal decomposition of Fe(III) oleate, mandelate, or glucuronate in high- boiling solvents at temperature >285 řC. Size of the particles was controlled in the range of 8- 27 nm by changing reaction parameters, i.e., temperature, type of iron precursor, and concentration of stabilizer (oleic acid and/or oleylamine), while preserving uniformity of the nanoparticles. Because particles contained hydrophobic stabilizer on the surface, they were dispersible only in organic solvents. To ensure water dispersibility, oleic acid on the particle surface was replaced by hydrophilic and biocompatible methoxy-poly(ethylene glycol) (PEG) and poly(3-O-methacryloyl-α-D-glucopyranose) by ligand exchange. Polymers were previously terminated with anchoring-end groups (hydroxamic or phosphonic) to provide firm bonding to iron atoms on the particle surface. Fe3O4 nanoparticles were also hydrophilized by encapsulation into a silica shell by reverse microemulsion method. Tetramethyl orthosilicate was used to prepare Fe3O4@SiO2 nanoparticles, which were...

Superparamagnetic -Fe2O3 nanoparticles were synthesized by coprecipitation of ferric and ferrous salts with a base. Resulting nanoparticles were coated with shells, such as poly(N,N- dimethylacrylamide) (PDMAAm), neat and functionalized silica (SiO2 and SiO2-NH2), and polyaniline (PANI). PDMAAm shell was introduced by modification of iron oxide nanoparticle surface with an initiator and N,N-dimethylacrylamide was polymerized producing -Fe2O3&PDMAAm core-shell particles. In case of SiO2-NH2 shell, tetramethyl orthosilicate was used to yield -Fe2O3&SiO2 nanoparticles, which were subsequently modified by (3-aminopropyl)triethoxysilane to prepare γ-Fe2O3&SiO2-NH2 particles. Oxidation of aniline hydrochloride with ammonium persulfate in an aqueous solution of poly(N-vinylpyrrolidone) in the presence of iron oxides produced -Fe2O3&PANI nanoparticles. Finally, the last type of the particles was based on thionin-modified poly(carboxymethyl methacrylate) (PCMMA&Th). The particles were characterized by techniques, such as scanning and transmission electron microscopy (SEM and TEM) and dynamic light scattering (DLS) to determine the particle morphology and hydrodynamic diameter. The presence of the functional groups, chemical composition, and the iron content were investigated by Fourier-transform...

In der vorliegenden Arbeit werden Untersuchungen zu amorphen Zink-Zinn-Oxid Dünnschichten beschrieben. Unter anderem wurde eine Methode zur Herstellung von Dünnschichten mit lateralem Kompositionsgradienten mittels gepulster Laserabscheidung genutzt. Die untersuchten elektrischen und optischen Eigenschaften der Dünnschichten in Abhängigkeit vom Zink-Zinn-Verhältnis werden hier dargelegt und mit den Eigenschaften von Filmen verglichen, welche keinen Kompositionsgradienten haben. Des Weiteren werden gleichrichtende Schottky-Kontakte diskutiert. Zunächst wird auf den Kontaktaufbau und die Auswahl des geeigneten Schottky-Metalls eingegangen. Dann wird die Modellierung des Stromtransports durch die Dioden vorgestellt. Mittels Defektspektroskopie gefundene Störstellenniveaus werden anschließend diskutiert. Untersuchungen an mittels gepulster Laserabscheidung ausschließlich bei Raumtemperatur gezüchteten pn-Dioden, welche die p-leitenden Materialien Zink-Kobalt-Oxid bzw. Nickeloxid beinhalten, werden dargelegt. Hierbei wird neben der Optimierung der Herstellungsparameter die Nutzung von flexiblem Polyimid als Substrat diskutiert. Die hergestellten Dioden wurden verschieden starken Verbiegungen ausgesetzt, um zu testen, ob sie grundlegend für die Anwendung in flexiblen Schaltungen geeignet sind. Im letzten Teil der Arbeit werden Untersuchungen an Sperrschicht-Feldeffekttransistoren beschrieben. Deren Gate-Struktur wird durch die vorher beschriebenen pn-Dioden realisiert. Es wird hierbei der Einfluss des Gate-Materials auf die Transistorkennlinien beschrieben. Zusätzlich werden auf den Transistoren basierende Inverterstrukturen diskutiert. Sowohl die Sperrschicht-Feldeffekttransistoren als auch die Inverter wurden außerdem auch auf flexiblen Substraten abgeschieden. Die Eigenschaften der Proben, bevor und nachdem sie mechanischem Stress durch Verbiegen ausgesetzt wurden, werden in der Arbeit verglichen.

Starting off with solubility experiments of possible precursors, the present study reveals the whole development of a sol gel processing route for transparent p type semiconductive thin films with delafossite structure right to the fabrication of functional p-n junctions. The versatile sol formulation could successfully be modified for several oxide compositions, enabling the synthesis of CuAlO2, CuCrO2, CuMnO2, CuFeO2 and more. Although several differences in the sintering behaviour of powders and thin films could be observed, the powder experiments significantly contributed to the clearification of the intricate phase development during thermal annealing and also to optimization of the annealing sequence for thin film processing. Two different ternary systems turned out to be the most promising candidates for p-TCO application: Copper aluminum oxide for its high optical transmittance and copper chromium oxide for its low synthesis temperature, which allowed thin film deposition on low-cost borosilicate substrates. In order to combine the advantages of these two systems, the quaternary oxide composition CuAl1-xCrxO2 was investigated. With a higher optical transmittance than CuCrO2, a lower synthesis temperature than CuAlO2 and a lower resistivity than both parent systems, the optimum composition of the quaternary oxide is reached for x = 0.50. Compared to physical vapour deposition techniques, the undoped thin films presented here still need to make up some deficites in their optoelectronic performance. Although the best sol-gel samples are able to compete with RF sputtered samples or sampes deposited by PLD in transmittance, their resistivity is almost two orders of magnitude higher. The most probable reasons for this are the characteristic imperfections of sol-gel thin films like porosity and small crystallite size, which create barriers like grain boundaries and bottlenecks like barely connected particles. By additional effort such shortcomings can be repelled to a certain extend, but nevertheless the density of undoped sol-gel material always stays behind its pendants processed by physical vapour deposition.[246] Furthermore, such additional endeavour is likely to annihilate the advantage of sol-gel technique in processing costs. Extrinsic doping is a common method to decrease the resistivity of delafossite materials. Partially replacing the trivalent cations by divalent ones creates additional holes and thus generates additional charge carriers for p-type semiconductivity. This can improve the conductivity of delafossites by up to three orders of magnitude. Due to the compositorial flexibility of sol-gel processing, dopants could be introduced easily in this study by soluble precursors. However, improving the conductivity of CuAlO2 and CuAl0.5Cr0.5O2 via this method failed. Actually, this seems to be due to the fact that instead of being incorporated into the delafossite phase the dopant ions form intransparent phase impurities like spinels, which interfere with optical transmittance of the thin films. On the contrary, doping had a positive effect on the conductivity and the optical transmittance of copper chromium oxide, with magnesium being the most effective dopant. The resistivity could be decreased by more than three orders of magnitude, but in order to achieve this, much higher Mg concentrations than by other thin film deposition methods were necessary. This indicates a low doping efficiency in sol gel processed thin films, but also the ability of sol gel processing to incorporate more magnesium into the oxide than any other processing method. The extensive substitution of the chromium ions also increases the optical transmittance and allows sol gel processed thin films to draw level with thin films deposited by sputtering methods or PLD. Finally, the applicability of the delafossite thin films was proven by the asymmetric current voltage characteristics of heterojunctions between ITO and the delafossites. Shunting problems of the metallic contacts, on the other hand, reveal structural deficites of the delafossites, which should be the subject of further investigations. / Ausgehend von Versuchen zur Löslichkeit möglicher Ausgangsstoffe zeigt die vorliegende Studie die komplette Entwicklung einer Sol-Gel-Route für die Synthese transparenter p-halbleitfähiger Dünnschichten mit Delafossitstruktur bis hin zur Herstellung funktionstüchtiger p-n-Übergänge. Die vielseitige Solrezeptur konnte erfolgreich für mehrere Oxidzusammensetzungen abgewandelt werden, was die Synthese von CuAlO2, CuCrO2, CuMnO2, CuFeO2 und weiteren Mischoxiden ermöglichte. Obwohl einige Unterschiede im Sinterverhalten von Pulvern und Dünnschichten beobachtet werden konnten, trugen die Pulverversuche erheblich zur Aufklärung der komplizierten Phasenentwicklung während der thermischen Behandlung und auch zur Optimierung der Kalzinierungsschritte bei der Dünnschichtherstellung bei. Zwei der ternären Oxide erwiesen sich als die vielversprechendsten Kandidaten für die Anwendung als p-halbleitfähiges transparentes Oxid: Kupfer-Aluminium-Oxid aufgrund seiner hohen optischen Transparenz und Kupfer-Chrom-Oxid aufgrund seiner niedrigen Synthesetemperatur, die die Abscheidung von Dünnschichten auf kostengünstigen Borosilicatglas-Substraten ermöglicht. Um die Vorteile dieser beiden Systeme zu vereinen, wurde die quaternäre Oxidzusammensetzung CuAl1-xCrxO2 untersucht. Mit einer höheren optischen Transmission als CuCrO2, einer niedrigeren Synthesetemperatur als CuAlO2 und einem geringeren spezifischen Widerstand als die beiden Muttersysteme wird die optimale Zusammensetzung dieses quaternären Oxids bei x = 0,50 erreicht. Im Vergleich zu Methoden der physikalischen Gasphasenabscheidung müssen die hier vorgestellten undotierten Dünnschichten noch einige Defizite bei ihren optoelektronischen Eigenschaften aufholen. Obschon die besten Sol-Gel-Proben in puncto Transparenz mit Proben, die über Radiofrequenz-Kathodenzerstäubung oder Laserstrahlverdampfen hergestellt wurden, mithalten können, liegt ihr spezifischer Widerstand um zwei Größenordnungen höher. Die wahrscheinlichste Ursache hierfür sind die charakteristischen Unvollkommenheiten von Sol-Gel-Dünnschichten wie Porosität und geringe Kristallitgröße, die den Stromfluss durch Hindernisse wie Korngrenzen und Engpässe wie schlecht verknüpfte Partikel behindern. Durch zusätzlichen Aufwand können derartige Unzulänglichkeiten in gewissem Maße zurückgedrängt werden, doch nichtsdestotrotz liegt die Dichte von undotiertem Sol-Gel-Material immer unter der von vergleichbaren Proben, die über physikalische Gasphasenabscheidung hergestellt wurden.[246] Zudem ist es wahrscheinlich, dass solche zusätzlichen Anstrengungen die Vorteile des Sol-Gel-Verfahrens bei den Herstellungskosten zunichte machen. Extrinsische Dotierung ist ein gängiger Weg, um den spezifischen Widerstand von Delafossit-Materialien abzusenken. Teilweiser Austausch der dreiwertigen Kationen durch zweiwertige erzeugt zusätzliche Löcher und stellt so zusätzliche Ladungsträger für die p-Halbleitung bereit. Dies kann die Leitfähigkeit von Delafossiten um bis zu drei Größenordnungen erhöhen. Dank der stofflichen Flexibilität des Sol-Gel-Verfahrens konnten in dieser Studie Dotanden sehr leicht in Form von löslichen Vorstufen eingebracht werden. Jedoch scheiterten die Versuche, die Leitfähigkeit von CuAlO2 und CuAl0,5Cr0,5O2 auf diesem Wege zu verbessern. Dies scheint darauf zurückzuführen zu sein, dass die Dotanden nicht in die Delafossitphase eingebaut werden, sondern intransparente Fremdphasen wie Spinelle bilden, die die optische Transmission der Dünnschichten beeinträchtigen. Im Gegensatz dazu wirkte sich die Dotierung positiv auf die Leitfähigkeit und die optische Transmission von Kupfer-Chrom-Oxid aus, wobei Magnesium als Dotant die besten Resultate lieferte. Der spezifische Widerstand konnte so um mehr als drei Größenordnungen verringert werden, doch wurden hierfür deutlich höhere Magnesiumkonzentrationen benötigt als bei anderen Beschichtungsverfahren. Einerseits weist dies auf eine geringe Dotiereffizienz in den über das Sol-Gel-Verfahren hergestellten Proben hin, andererseits zeigt dies aber auch, dass über das Sol-Gel-Verfahren wesentlich mehr Magnesium in die Oxidschichten eingebracht werden kann als über jedes andere Verfahren. Der beträchtliche Ersatz der Chromionen erhöht auch die optische Transmission und ermöglicht es den Sol-Gel-Proben, zu den Dünnschichten aufzuschließen, die durch Kathodenzerstäuben oder Laserstrahlverdampfen hergestellt wurden. Schließlich wurde das Anwendungspotential der Delafossit-Dünnschichten durch die asymmetrischen Strom-Spannungs-Kennlinien von p-n-Übergängen zwischen Delafossit und Indium-Zinn-Oxid belegt. Andererseits machen die Kurzschlussprobleme bei der metallischen Kontaktierung die strukturellen Defizite der Delafossite deutlich. Dies sollte zum Gegenstand weiterführender Untersuchungen werden.