Halle, Universiẗat, Diss., 1999.

The worldwide growing demand for clean energy leads to necessity for new energy generation methods. Nuclear power generators are an excellent solution for these demands. The feasibility of nuclear power production depends on the performance of structural materials under the harsh conditions in nuclear reactors such as high radiation flux and high temperature. The development of structural materials to withstand such conditions is a big challenge and crucial for advanced nuclear fission and fusion reactors. Several materials are developed, amongst them Oxide Dispersion Strengthened (ODS) steels also called Nanostructured Ferritic Alloys (NFA). NFA consist of Fe-Cr based ferritic/martensitic steels that contain highly dispersed nanometer-size Y-Ti-O nanoclusters, and are manufactured via powder metallurgy. The presence of nanoclusters leads to high temperature stability and radiation resistance. Despite many research activities using advanced analytical techniques such as Transmission Electron Microscopy and Atom Probe Tomography as well as theoretical calculations many properties of the nanoclusters, such as the detailed atomic structure and composition as well as their efficiency for trapping He, vacancies and self-interstitial atoms (SIA), are still not completely understood. In the first part of this thesis work, six different structural models for atomic clusters in bcc Fe which may contain O, Y, Ti, and vacancies (v) are investigated by Density Functional Theory (DFT) calculations. Results for clusters with identical numbers of constituents (O, Y, Ti, and v) are compared. The most important finding consists in the statement that the data on the stability or energetics of the relaxed clusters are comparable although their atomic configurations are often different. This contradicts the prevailing opinion in the related theoretical literature that favors the so-called structure-matching model, which is also investigated in this work. In all studied cases, the absolute value of the total binding energy per cluster constituent becomes lower if Y is partially replaced by Ti, i.e. the driving force for the growth of O-Y clusters is higher than that of O-Y-Ti clusters. This may be correlated with the experimental observation that the presence of Ti leads to a reduction of the size of the oxide clusters in NFA and to a higher dispersion. A further major result is the finding that cage-like (CL) clusters and clusters with an oxygen atom in the center (cage) have a similar total binding energy. If Ti is not present such clusters are slightly more stable than the corresponding CL clusters. The opposite holds for clusters with Ti. It is also shown that adding O atoms to CL cluster leads to structures with O in the center. Vacancies are an important for the stabilization of the cluster due to the very strong binding with O. We infer that the Ov pair may be the origin for cluster nucleation growth. Because of limited computational resources, the dimension of clusters investigated by DFT is still below or close to the limit of the experimental resolution of methods allowing for a simultaneous determination of atomic structure and composition of the clusters. These small clusters may be considered as nuclei for further structural evolution and growth during which a selection of the most favored cluster structures could occur. In the second part of the work four different cluster structures are used to investigate their ability to trap irradiation defects He, v and SIA. These defects are inserted on different positions inside and in the environment of the clusters, the total energy of the corresponding supercell is minimized by DFT, and the binding and incorporation energy of the three kinds of defects is determined. He in the center of a CL cluster is more stable than on interfacial vacant sites (IVS). In CL O-Y clusters, He on an IVS is more stable than in clusters with oxygen in the center, whereas there is no significant difference between the two kinds for clusters with Ti. Up to a distance of 1.5 times the iron lattice constant from the cluster center He is not stable on most of the octahedral and tetrahedral interstitial sites in the Fe matrix. Instead, He is shifted towards positions closer to the cluster. Relaxation occurs to known IVS as well as to previously unknown interfacial interstitial sites (IIS). Moreover, two or three He atoms are placed on sites found to be stable after adding a single He. The corresponding binding and incorporation energies obtained after relaxation are nearly equal to the sum of the values for the interaction with a single He atom. However, placing He dimers or trimers in the environment of a vacancy that belongs to the cluster may also lead to relatively low values of the incorporation energy. Also, He jump barriers between interfacial sites and the center of CL clusters are determined. In the CL O-Y cluster, the barriers are lower than in the CL O-Y-Ti cluster, i.e. trapping and release of He is easier in the former than in the latter. The main reason for the high He trapping efficiency is the low electron density in the empty regions of the oxide-like structure of the clusters. Vacancy and SIA interaction with the clusters is also attractive. The binding energy of a vacancy strongly depends on the site where the vacancy is inserted while in all the studied cases the SIA is annihilated at the cluster-iron interface. Present results clearly demonstrate that the oxide-based nanoclusters are strong traps for irradiation-induced defects, which is in agreement with experimental findings.

The aim of this thesis is to design a desulphurization device for the fluid boiler. In the fluid boiler, fuel with extremely high sulphur content is burnt and the combustion products are not desulphurized to the required level, therefore it is necessary to build a desulphurization device. The thesis consists of two parts – theoretical and practical. In the theoretical part I stated the emission limits of sulphur dioxide, elaborated possible desulphurization methods and described the sorbets suitable for desulphurization. In the practical part I chose a dry desulphurization method with fluid reactor, to which a dry sorbent on the basis of lime hydrate is dosed. For the required parameters, I designed the whole desulphurization equipment including cloth filters, all necessary silos and major components. It is a design proposal with a layout and a spatial model.

The aim of this thesis is to design a desulphurisation device for the pulverized coal boiler K3 in heating plant Olomouc. In this boiler, coal with sulphur content is burnt. Emissions SOx from the boiler output are much higher than the emission limits for SOx, which comes into force 1.1.2016. Therefore it is necessary to build a desulphurisation device, which will cause a significant reduction of SOx emissions and compliance with the emission limits. The thesis consists of two parts - theoretical and practical. The theoretical part states SO2 emission limits and describes various methods for flue gas desulphurisation. In the practical part I chose a semi-dry desulphurisation method with fluid reactor. It determines a stoichiometric amount of combustion air and determines the boiler efficiency. For the required parametres is given a calculation of desulphurisation, the design of some parts of the device and design arrangement.

This work is concerning the study of model ceria based calalysts structure by methods of electron diffraction RHEED and photoelectron spectroscopy XPS. The influence of deposition conditions and substrate on the growth of epitaxial cerium oxide films on copper single crystals is described in detail. The work then describes the interaction of cerium and tin in model systems and the creation of SnCeOx mixed oxide and its structure. In the last chapter, the interaction of palladium with cerium and tin oxide layers is examined, and the creation of paladium bimetallic alloys is described. Powered by TCPDF (www.tcpdf.org)

The thesis is focused on the investigation of fundamental catalytic properties of two model catalysts-CeOx/Cu(111) and CuOx/Cu(111)-by means of advanced surface science techniques. The investigations performed on CeOx are devoted to the study of the relationship between the surface structure and the surface activity of ceria. We develop the preparation method leading to growth of epitaxial CeOx(111) thin films with the adjustable morphological parameters-the step density and the ordering of surface oxygen vacancies. By using the CeOx(111) films with precisely controlled structure we identify the role of the step edges and of the oxygen vacancies in the interaction of water with ceria. The investigation performed on CuOx is focused on the microscopic characterization of the reduction process of Cu2O(111) on the molecular level directly under a near ambient pressure of CO. In direct microscopic study we identify the active initiation centers, the intermediate oxide phases, and the kinetics of the reduction reaction of Cu2O(111).

This diploma thesis focuses on the fabrication of ceramic fibres by electrospinning. The theoretical part of the thesis summarizes the currently available information regarding ceramic fibres, their properties, applications and fabrication. The theoretical part also describes the process of electrospinning as one of the most frequently used methods of nanofibre fabrication, as well as the parametres influencing this process. The experimental part is aimed at the fabrication of ceramic fibres based on titania, pure non-doped zirconia and yttria-doped zirconia by electrospinning and at the characterization of thus fabricated fibres. Ceramic precursors based on propoxide and polyvinylpyrrolidone were subjected to electrospinning. The experimental part of this diploma thesis also describes the influence of precursor composition, process conditions and calcination temperature on the morphology and phase composition of the fibres. Precursors were characterized by viscosity measurements. Thermogravimetric analysis (TGA), Röntgen analysis (RTG) and scanning electron microscopy (SEM) were used to describe the fibres. By performing electrospinning of precursors based on titanium propoxide and subsequent calcination at 500-1300 °C, TiO2 fibres with thickness of 100-2500 nm were fabricated. The phase composition changed with calcination temperature from 500 °C from anatase phase through rutile blend to pure rutile at 900 °C. By performing electrospinning of precursors based on zirconium propoxide and subsequent calcination at 550-1100 °C, 0 – 8 mol% Y2O3 doped ZrO2 fibres with thickness of 50-1000 nm were fabricated. An analysis of fibres based on non-doped ZrO2, calcined at 550 °C showed a composition of predominantly monoclinic phase. An analysis of 3 or 8 mol% Y2O3 doped ZrO2 fibres calcined at 900 °C showed a composition of predominantly tetragonal phase or purely cubic phase, respectively. With the increasing calcination temperature, the morphology of the fibres changed from porous nanostructure to chain-like non-porous structure consisting of micrometer grains of TiO2 or ZrO2. The ZrO2 fibres calcined at 700 °C remained flexible as well as the spun ones, while their fragility increased with the increase in calcination temperature.

Master thesis “Properties of graphenoid layers” deals with materials of graphenoid nature such as graphene, graphene oxide and its reduced state. The paper effectively summarize basic theoretical knowledge in the first half of its range. In the second half the project deals with practical part consisted of experiments with application of graphene oxide solvents, its analysis and especially comparing properties of non-reduced graphene oxide with its chemically reduced form. Material is examined in a form of applied thin layers on different substrates.

Name of the thesis Effect of nitric oxide on cerebral blood flow during neuronal activity Aim of the thesis The aim of this thesis is to determine whether the application of 7-nitroindazole, relatively specific inhibitor of neuronal nitric oxide synthase, affects the baseline blood pressure. Furthermore, to determine whether the application of the substance affects the baseline cerebral blood flow and whether it influences blood flow in brain during transcallosal stimulation with increasing frequency. Research method The research took place at the premises of the Institute of Physiology, Academy of Sciences of the Czech Republic. Experiments were carried out on laboratory albino Wistar rats. The group contained both experimental and control sample. General anesthesia was performed to rats, stimulating and sensing electrodes were implanted in epidural area of sensorimotor cortex and Laser Doppler flow probe was implanted into the contralateral hemisphere. A plastic catheter was applied in the carotid artery for measuring systemic blood pressure. In the first part of the experiment, we tested the effects of 7-nitroindazole on the systemic blood pressure. In the second part of the experiment, we investigated the effects of 7-nitroindazole on baseline cerebral blood flow. The third part of the...

Title: The role of nitric oxide in the pathophysiology of neurodegenerative diseases Objectives: The main objective of this thesis is to evaluate the effect of nitric oxide on the formation and development of neurodegenerative diseases. Another objective was to determinate, whether NO affects by its impact processes involved in apoptosis in the CNS. Methods: The thesis is prepared in the form of research, drawing from available relevant resources. Results: Nitric oxide is widely applied in the pathophysiology of selected neurodegenerative diseases, either directly or through other reactive nitrogen and oxygen. It also affects other factors that are involved in apoptosis in the CNS. Keywords: Nitric oxide, NMDA receptors, neurodegenerative diseases, excitotoxicity, apoptosis