<p>In this thesis 9-12 % Cr steels, used for high-temperaturecomponents in fossil-fired power plants are considered. Thecreep strength of thees steels depend on their microstructurethat consists of a matrix of tempered lath martensite withdensely distributed precipitates. The mechanical properties arestrongly influenced by precipitates present in the matrix andthe more densely distributed they are the higher is thehardening effect. These particles nucleate, grow and coarsenduring use in power plants, leading to a degradation ofmechanical properties. In this thesis the nucleation andcoarsening behaviour of the precipitates in the Cr steels aresimulated by new models and the results are compared withtransmission electron microscopy (TEM) observations of testedmaterials.</p><p>A model of the nucleation of MX, which mainly isvanadium-nitrides, is presented. MX precipitates are assumed tonucleate on dislocations during annealing. The model takes intoaccount the full multicomponent thermodynamical behaviour ofthe system as well as the strain energy caused by a puredilatoric strain and the shape of the nucleus. The calculationsyield a critical size and shape represented by an oblatespheroid with a radius of a few nanometers and a thickness ofan atomic layer. This is in agreement with TEM observations ofsupercritical particles.</p><p>A new coarsening model, which takes into account themulticomponent effects, is presented and it has been tested ondifferent systems to validate the model.</p><p>    Four different carbides, Cr₇C₃, Mo₆C, VC and NbC, in austenitic matrix as well asγ ' in ternary Ni-base super-alloy systems (Ni-Al-Mo)were compared with measurements from literature.</p><p>    TiC-particles in austenitic stainless steel, ASTM 316Ti,were considered. The simulations were performed taking intoaccount iron and 7 alloying elements. The measurements wereperformed with TEM on samples that had been heat-treated at900° C.</p><p>    MX and M₂₃C₆in a 9 % Cr steel were investigated with energyfiltering transmission electron microscopy (EFTEM) andcompared with simulations. The used samples had been heattreated for various periods of time at 600 and 650° Cfor up to 26 000 h.</p><p>The agreement of the simulations with the experiments wasgood in all cases when reasonable values of the interfacialenergy, the only adjustable parameter, were chosen.</p><p>Coarsening simulations were also performed to investigatethe influence of changes in composition on the coarsening rate.For MX, in a 9 % Cr steel, the coarsening rate is almostindependent of the V/Nb ratio but highly dependent on theN-content. Also the effect on the coarsening rate for M₂₃C₆by adding Co to a Cr steel was investigated bysimulation. Co is known to increase the resistance totempering. The results show that a final average radius of thecarbides after 30 000 h at 600° C decreases with 30 % witha Co addition of 10 mass %.</p><p><b>Keywords:</b>Cr steels, nucleation, coarsening, model,DICTRA, precipitates, carbides, carbo-nitrides, MX, VN, M₂₃C₆, TiC, TEM, EFTEM, Curie-temperature</p>

La thèse décrit la première synthèse totale de l'Eucophylline, le fragment sud de l'alcaloïde Leucophyllidine récemment isolé à partir de Leuconotisgriffithii et L. eugenifolius. La synthèse en 10 étapes comprend une nouvelle méthode d’accès au squelette azabicyclo[3.3.1]nonane par un processus de carbooximation radicalaire d'oléfines à trois composants. Au cours de ces études, nous avons également isolé des énamines présentant des stabilités inhabituelles résultant de leur conformation bicyclique tendue. La synthèse de la partie éburnane, le fragment nord de la Leucophyllidine, a été réalisée grâce à une nouvelle réaction radicalaire de carbo-cyanation à trois composants. Cette réaction radicalaire s'est révélée efficace pour installer le groupement fonctionnel nitrile sur des oléfines, et éventuellement former des centres quaternaires, notamment dans des structures complexes, puisqu'une bonne tolérance aux différents groupes fonctionnels a été observée. Le couplage biomimétique entre le squelette éburnane et l'Eucophylline a finalement été étudié en utilisant des modèles de structure similaire. Les résultats préliminaires de cette étude ont montré que l'absence d'effet gem-diméthyle dans le modèle éburnane empêche probablement la formation de l'imine cyclique,intermédiaire-clé dans le couplage désiré. / The thesis describes the first total synthesis of Eucophylline, the south fragment of the Leucophyllidine alkaloid recently isolated from Leuconotis griffithiiand L. eugenifolius. The 10-step synthesis encompasses a new straight forward method to access to the azabicyclo[3.3.1]nonane skeleton through a free-radical three-component olefinic carbo-oximation process. During these studies, we also isolated enamines exhibiting unusual stabilities resulting from their strained bicyclicconformation. The synthesis of the Eburnane part, the north fragment of Leucophyllidine, was developed relying on a new free-radical three-component Carbo-Cyanation reaction. This new reaction showed high tolerance toward different functional groups and provided an efficient mean to install the nitrile group in complex structures and to introduce quaternary centers. The biomimetic coupling between the Eburnane and Eucophylline fragments was finally studied using structurally similar models. Preliminary results of this model study showed that absence of a gemdimethyleffect in the Eburnane model probably prevents the formation of the cyclicimine, key intermediate for the desired coupling.

(I) Background. Conflicts emerge when populations of protected species grow to sizes that cause noticeable economic damage - like in the case of the fish consuming Great Cormorant (Phalacrocorax carbo sinensis). One possible approach for reconciliation is to regulate the size of the population in question. In doing so, regulation strategies have to meet multiple targets: 1) population size has to be reduced; 2) the viability of the population has to be maintained; 3) strategies have to adhere to the available budget. This thesis focuses on the regulation of populations that are structured into two groups - breeders and mature non-breeders. The pool of non-breeders provides a reserve for the breeders, whereby they may enable the population to resist regulation attempts. (II) Aims. 1) Development of a modeling framework and a conceptual model to provide an understanding of the functioning and effect of the population structure induced by non-breeders on population dynamics in a fluctuating environment. 2) Uncover the relation between non-breeder characteristics and the performance of regulation strategies. 3) Application of the modeling approach to the regulation of the Cormorant in order to evaluate the results from the conceptual model and find statements to support decisions on management strategies. (III) Methods. A conceptual stochastic time-discrete model, based on the logistic map with overlapping generations, is developed. Different types of threshold regulation strategies are applied. Strategies differed in which part of the model was affected by regulation. Resulting rules from the conceptual model are tested by applying them to a second age-structured model of a cormorant population, parametrized with data gained from a cormorant colony in Denmark. Analyzes of this model focus on the ecological-economic performance of regulation strategies and result in rankings of regulation options. Regulation performance is judged from different economic perspectives.

The herbal preparation coffee charcoal is produced by over-roasting and milling green dried Coffea arabica L. seeds, and has a long-standing tradition in the treatment of inflammatory and gastrointestinal disorders. Its therapeutic properties are commonly attributed to adsorptive and astringent effects. This insufficiently explains its mode of action, especially when used in the treatment of inflammatory diseases in lower dosages. Our investigations aimed to identify bioactive secondary plant metabolites affecting cytokine-signaling. Thus, a phytochemical analysis of coffee charcoal extract was conducted using HPLC and LC/MS. Trigonelline, neochlorogenic acid, chlorogenic acid, caffeine, cryptochlorogenic acid, feruloylquinic acid isomers, and a caffeoylquinolacton were identified in the extract. Subsequently, the effects of coffee charcoal extract, chlorogenic acid isomers, their metabolite caffeic acid, caffeine, and trigonelline on cytokine (TNF, IL-6, MCP-1) release from LPS-challenged human THP-1 macrophages were examined to evaluate anti-inflammatory activity. Coffee charcoal showed concentration-dependent mild-to-medium inhibitory effects. The chlorogenic acid isomers and caffeic acid inhibited the TNF release, with cryptochlorogenic acid exerting the most distinct effects, as well as decreasing the release of IL-6 and MCP-1. In addition, scanning electron microscopic images provided an impression of the particle constitution, indicating a larger particle size and less structured surface of coffee charcoal in comparison to activated charcoal. In conclusion, our findings underline that beyond adsorptive effects, coffee charcoal exhibits pharmacological properties, which derive from a spectrum of secondary plant metabolites and support the therapeutic use in inflammatory diseases. Chlorogenic acids, particularly cryptochlorogenic acid, appear as pivotal bioactive compounds.

The submitted M.Sc. thesis describes development in populations of the bird and mammalian species, having been involved in human - wildlife conflicts, particularly of the specially protected species, in the Czech Republic as well as in compensation payments for damages caused on private properties by the selected specially protected wild animal species. At the same time, it compares various tools, applied to solve human - willdife conflicts in the different parts of the world. The study presents information provided by governmental authorities or gained from grey literature, expert databases and scientific papers. Trends both in the development in conflict species populations and in compensation payments were assessed and the relationship between both variables was found. In total, payments for damages caused by conflict wild animal species has been increasing in the Czech Republic since 2000, but trends in the conflict species populations differ from each other, influenced particularly by their bionomics. The analysis performed shows, that the act on the topic is effective only for some of the above wild animal species. For large carnivores, namely the Grey Wolf (Canis lupus), Eurasian Lynx (Lynx lynx) and Brown Bear (Ursus arctos), the above tool does not provide suitable solutions for their...

La substitution ionique apparait comme une des possibilités pour moduler la bioactivité de l’hydroxyapatite (HA), matériau couramment employé comme substitut osseux. L’incorporation simultanée d’ions carbonates et silicates dans la structure apatitique pourrait permettre de coupler les propriétés de résorption et de dissolution des apatites carbonatées avec le rôle métabolique important du silicium dans le tissu conjonctif.Des poudres d'hydroxyapatites phosphocalciques substituées en carbonates et en silicates de formule Ca10 x+y(PO4)6-x-y(CO3)x(SiO4)y(OH)2-x+y (avec 0 ≤ y ≤ x ≤ 2 et x+y ≤ 2, C Si HA), ont été synthétisées par précipitation en milieu aqueux. L’originalité de cette synthèse réside essentiellement dans l’emploi de réactifs parfaitement solubles et miscibles dans l’eau. L’incorporation des carbonates et des silicates en substitution des phosphates a lieu dès la précipitation. Les poudres obtenues sont monophasiques, cristallines et de structure apatitique.Les caractérisations physico-chimiques des poudres ont mis en évidence l’existence d’interactions entre les carbonates (A et B) et les silicates au sein de la maille apatitique. La décarbonatation des sites B, synonyme de décomposition de la phase C-Si-HA, a pu être décalée à de plus hautes températures avec l’emploi du CO2 comme atmosphère de calcination. Le frittage de céramiques denses et monophasiques en C Si HA destinée à une première évaluation biologique a donc été possible. La culture in vitro de cellules souches mésenchymateuses C3H10T1/2 à la surface de céramiques de composition C0,8 Si0,4 HA a mis en évidence leur biocompatibilité et des propriétés ostéoconductives équivalentes à celles de l’HA. / Ionic substitution appears as one possibility to modulate the bioactivity of hydroxyapatite (HA), which is a material commonly used as bone substitute due to its chemical and crystallographic similarities with bone mineral part. The simultaneous incorporation of silicates and carbonate ions in the apatite structure could allow coupling the resorption and dissolution properties of carbonate apatite with the important metabolic role of silicon in the connective tissue.Co-substituted hydroxyapatite powders, of assumed composition Ca10 x+y(PO4)6-x-y(CO3)x(SiO4)y(OH)2-x+y (with 0 ≤ y ≤ x ≤ 2 et x+y ≤ 2, C Si HA), with controlled amount of carbonate (x) and silicate groups (y), were synthesized by means of a wet precipitation method. The innovative character of this synthesis process lies in the use of completely soluble and miscible reagents in water. According to this method, silicates and carbonates substitution for phosphate ions into the apatitic structure occurs from precipitation. The powders obtained are monophasic, crystalline and apatitic.The physicochemical characterizations of powders revealed the existence of interactions between carbonates (A and B) and silicates within the apatitic structure. C Si HA phase decomposes when B-type carbonate are released from the structure. The use of CO2 throughout the heat treatment allows to shift the B sites decarbonatation to higher temperature than under inert atmosphere. The sintering of dense and monophasic ceramic in C Si HA was realized. In vitro culture of mesenchymal stem cells C3H10T1/2 on the surface ceramics showed equivalent biocompatibility and osteoconductive properties between HA and C-Si-HA (x=0.8, y=0.4) phases.

<p>The strong increase in number of Great cormorants <i>Phalacrocorax carbo</i> in Sweden in recent years has led to conflicts - particularly with fishery. This thesis focuses on the possible effects of cormorant predation on fish populations. In total, data from 15 lakes in South Sweden were included in this study while most studies were carried out in Lake Ymsen. The results suggest that the impact of cormorant predation on natural fish populations was small, and I observed no decline in fish mass after cormorants established. Cormorant predation on eel was difficult to evaluate because of several confounding factors.</p><p>Ruffe, roach and perch were the most important prey species to the cormorants and most fish taken were small. Cormorants do not seem to catch species and sizes in proportion to their occurrence in the fish community.</p><p>Total fish removal by cormorants varied considerably among lakes (0.2-15.0 kg/ha) and cormorant population sizes at the different lakes were significantly positively correlated with fishery catches, which in turn was significantly positively correlated with total phosphorous levels. Thus, cormorant densities in lakes, and perhaps elsewhere, seem to be governed chiefly by fish densities. The fact that cormorant predation appears not to reduce fish densities suggest cormorants to be regulated by other means than prey depletion. The mechanism behind population regulation could be a behavioural response of fish, making fish more difficult to catch for the cormorants.</p><p>In recent years, cormorant populations have been subjected to intensive legal and illegal actions with the aim to reduce cormorant numbers. However, the actions currently carried are well below the efforts needed to limit population sizes. To conclude, cormorants appear to compete little with fishery, with regards to free-living fish. The main problem is that cormorants sometimes damage and take away fish in fishing gears.</p>

The strong increase in number of Great cormorants Phalacrocorax carbo in Sweden in recent years has led to conflicts - particularly with fishery. This thesis focuses on the possible effects of cormorant predation on fish populations. In total, data from 15 lakes in South Sweden were included in this study while most studies were carried out in Lake Ymsen. The results suggest that the impact of cormorant predation on natural fish populations was small, and I observed no decline in fish mass after cormorants established. Cormorant predation on eel was difficult to evaluate because of several confounding factors. Ruffe, roach and perch were the most important prey species to the cormorants and most fish taken were small. Cormorants do not seem to catch species and sizes in proportion to their occurrence in the fish community. Total fish removal by cormorants varied considerably among lakes (0.2-15.0 kg/ha) and cormorant population sizes at the different lakes were significantly positively correlated with fishery catches, which in turn was significantly positively correlated with total phosphorous levels. Thus, cormorant densities in lakes, and perhaps elsewhere, seem to be governed chiefly by fish densities. The fact that cormorant predation appears not to reduce fish densities suggest cormorants to be regulated by other means than prey depletion. The mechanism behind population regulation could be a behavioural response of fish, making fish more difficult to catch for the cormorants. In recent years, cormorant populations have been subjected to intensive legal and illegal actions with the aim to reduce cormorant numbers. However, the actions currently carried are well below the efforts needed to limit population sizes. To conclude, cormorants appear to compete little with fishery, with regards to free-living fish. The main problem is that cormorants sometimes damage and take away fish in fishing gears.

The present work was initiated to investigate the stability, structural and thermodynamic properties of transition metal carbides, nitrides and carbo-nitrides by atomistic simulations and experimentations. The interatomic pair potentials of Cr-Cr, Mn-Mn, Fe-Fe, C-C, Cr-C, Mn-C, Fe-C, Cr-Fe, Cr-N and Mn-N were inverted by the lattice inversion method and ab initio cohesive energies, and then employed to investigate the properties of Cr-, Mn- and Fe-carbides by atomistic simulations in this work. For the binary M7C3 carbide, the structural properties of M7C3 (M = Cr, Mn, Fe) were investigated by atomistic simulations. The results show that the stable structure for these compounds is hexagonal structure with P63mc space group. The cohesive energy of M7C3 calculated in this work indicates that the stability of carbides decreases with the increasing in metal atomic number. Further, the vibrational entropy of Cr7C3 was calculated at different temperatures and compared with the entropy obtained by experimentations. The comparison demonstrates that the main contribution to the entropy is made by the vibrational entropy. For the binary τ-carbides, the structural properties of Cr23C6 and Mn23C6, as well as the vibrational entropy of Cr23C6 were computed. Further, the site preference of ternary element Fe among 4a, 8c, 32f and 48h symmetry sites in Cr23-xFexC6 was studied. It has been seen that Fe atoms would firstly occupy 4a sites and then 8c sites. The lattice constant and stability of Cr23-xFexC6 were also computed with different Fe content. In order to understand the relative stability of the transition metal carbides and nitrides, the standard formation Gibbs energies of carbides and nitrides for Cr, Mn and Fe were compared. The order of carbon and nitrogen affinities for Cr, Mn and Fe was further clarified by the comparison of the interatomic pair potentials among Cr-C, Mn-C, Fe-C, Cr-N and Mn-N. It was found that Cr-N interaction was very strong in comparison with other binary interactions above and consequently, nitrogen addition would lead to a strong decrease in the thermodynamic activity of chromium in Cr-containing alloys. This was confirmed by the investigations of thermodynamic activities of Cr in the Fe-Cr-N and Fe-Cr-C-N alloys. The activities were measured in the temperature range 973-1173 K by solid-state galvanic cell method involving CaF2 solid electrolyte under the purified N2 gas. In addition, the analysis of nitrogen content and phase relationships in the Fe-Cr-N and Fe-Cr-C-N alloys equilibrated at 1173 K were carried out by inert-gas fusion thermal conductivity method, X-ray diffraction and scanning electron microscopy technique. The experimental results show that the solubility of nitrogen in the alloys decreases with the decreasing chromium content, as well as the increasing temperature. The addition of nitrogen to the alloys was found to have a strong negative impact on the Cr activity in Fe-Cr-N and Fe-Cr-C-N systems. / QC 20100929

La substitution ionique apparait comme une des possibilités pour moduler la bioactivité de l'hydroxyapatite (HA), matériau couramment employé comme substitut osseux. L'incorporation simultanée d'ions carbonates et silicates dans la structure apatitique pourrait permettre de coupler les propriétés de résorption et de dissolution des apatites carbonatées avec le rôle métabolique important du silicium dans le tissu conjonctif.Des poudres d'hydroxyapatites phosphocalciques substituées en carbonates et en silicates de formule Ca10 x+y(PO4)6-x-y(CO3)x(SiO4)y(OH)2-x+y (avec 0 ≤ y ≤ x ≤ 2 et x+y ≤ 2, C Si HA), ont été synthétisées par précipitation en milieu aqueux. L'originalité de cette synthèse réside essentiellement dans l'emploi de réactifs parfaitement solubles et miscibles dans l'eau. L'incorporation des carbonates et des silicates en substitution des phosphates a lieu dès la précipitation. Les poudres obtenues sont monophasiques, cristallines et de structure apatitique.Les caractérisations physico-chimiques des poudres ont mis en évidence l'existence d'interactions entre les carbonates (A et B) et les silicates au sein de la maille apatitique. La décarbonatation des sites B, synonyme de décomposition de la phase C-Si-HA, a pu être décalée à de plus hautes températures avec l'emploi du CO2 comme atmosphère de calcination. Le frittage de céramiques denses et monophasiques en C Si HA destinée à une première évaluation biologique a donc été possible. La culture in vitro de cellules souches mésenchymateuses C3H10T1/2 à la surface de céramiques de composition C0,8 Si0,4 HA a mis en évidence leur biocompatibilité et des propriétés ostéoconductives équivalentes à celles de l'HA.