Ces travaux de thèse ont porté sur l'étude approfondie de catalyseurs à base d'argent et d'or dans la réduction catalytique sélective des NOx par C3H6. Pour le système Ag/Al2O3, nous avons réussi à fournir une explication rationnelle de l'origine de l'existence d'un optimum d'activité pour une teneur en Ag de l'ordre de 2 %pds reporté à plusieurs reprises. La caractérisation par NOx-TPD des catalyseurs Ag/Al2O3 a permis d'attribuer l'origine de cet optimum à la teneur maximale en Ag pour laquelle la dispersion quasi-atomique de l'argent est préservée. Nous avons aussi démontré pour la première fois que l'activité des catalyseurs Ag/Al2O3 dans la réduction des NOx par C3H6 en présence de H2 augmentait lorsque la densité surfacique en Ag diminuait. Ceci a été expliqué par l'augmentation du nombre de sites du support pouvant adsorber les NOx lorsque la teneur en Ag diminue. Le système catalytique Au/Al2O3 a été également étudié. En diminuant le nombre de sites d'or dans le réacteur, un effet promoteur de H2 a été mis en évidence pour la première fois pour ce système dans la réduction des NOx par C3H6. Cet effet promoteur était plus important lorsque la teneur en Au diminue. L'activité catalytique du système Au/Al2O3 a été optimisée par la cérine, le catalyseur présentant 1%pds en CeO2 et 0,5%pds en Au a montré la meilleure conversion des NOx. L'activité catalytique d'un système Au-Ag/Al2O3 a également été examinée mais trouvée moins intéressante que celles des systèmes monométalliques. La conversion des NOx en N2 en présence de H2 sur un catalyseur Ag/Al2O3 a pu être améliorée de prés de 30 % en déposant l'argent sur un support prétraité hydrothermalement. / This work provides further insights into C3H6-SCR on alumina supported silver and gold catalysts. The origin of the optimum loading of 2 wt% of Ag on Al2O3 in the C3H6-SCR of NOx was elucidated with the help of an original characterization method (NOx-TPD). The optimum loading was attributed to the maximum loading of silver on Al2O3 for which highly dispersed Ag species are preserved. Our study highlights for the first time that the H2-C3H6-SCR catalytic performance of Ag/Al2O3 samples improved in the 150-550 °C temperature domain as the Ag loading decreased well below 2 wt%. A detailed kinetic study of H2-C3H6-SCR was performed and led us to conclude that the unexpected higher catalytic performance of the Ag samples with the lower Ag surface densities was attributed to the higher concentration of active sites on the Al2O3 supporting oxide able to chemisorb NOx species. Regarding Au/Al2O3 catalysts, our work provides the first experimental evidence of an H2 effect in C3H6-SCR over Au/Al2O3 catalysts. This effect could only be observed when the number of Au catalytic sites in the reactor was decreased. The influence of the Au loading on the H2-C3H6-SCR was investigated. Au/CeO2-Al2O3 system was optimized with addition of ceria. Among the Au/CeO2-Al2O3 catalysts evaluated, the sample containing 0.5 wt% Au and 1 wt% CeO2 exhibited the best NOx conversion in C3H6-SCR at low temperature (from 150 °C). The catalytic activity of bimetallic Au-Ag /Al2O3 catalysts was investigated in C3H6-SCR and H2-C3H6-SCR. Finally, NOx conversion to N2 on Ag/Al2O3 in H2-C3H6-SCR could be improved substantially by nearly 30 % when silver is added on hydrothermally pretreated Al2O3 support.

Doctor of Philosophy / Department of Chemistry / Kenneth J. Klabunde / This is an account of the synthesis of several drastically different forms of silver nanoparticles: Bare metal nanoparticles, dry nanoparticulate powders, aqueous soluble particles, and organic ligand coated monodisperse silver nanoparticles were all produced. The synthetic method was adapted from previous studies on gold nanoparticles and investigated to understand the optimal conditions for silver nanoparticle synthesis. Also the procedure for refinement of the nanoparticles was studied and applied to the formation of alloy nanoparticles. This extraordinary procedure produces beautifully colored colloids of spherical metal nanoparticles of the highest quality which under suitable conditions self-assemble into extensive three dimensional superlattice structures. The silver nanoparticle products were later tested against several biological pathogens to find dramatic increases in antimicrobial potency in comparison to commercially available silver preparations.

Philosophiae Doctor - PhD / Emerging micropollutants such as bisphenol-A and 2-nitrophenol present a great threat in drinking water due to their adverse effects. Most conventional technologies in water and wastewater treatment are not designed to eliminate these xenobiotics; instead pollutants are merely transferred from one phase to another. Advanced oxidation technologies (AOTs) however, have been identified as suitable routes for the degradation of these potential damaging substances based on free radical mechanisms and use of less expensive chemicals. Moreover, due to the structural complexity of wastewater and the existence of pollutants as mixtures, no single advanced oxidation technology can convincingly remove all forms of contaminants and then most often than not, a combination of treatment processes is required for an effective purification process. Besides, the problem of adequate degradation of emerging contaminants in the environment, when AOT(s) are used individually, they present inherent problems. For instance, powder TiO₂ photocatalysts obstruct light penetration, thus prevent effective interaction of UV light with the target pollutants, and particulates present problems of post-filtration and recovery of catalyst particles after treatment. Additionally, TiO₂ has a high band gap energy, high electron-hole recombination rate, and is prone to aggregation of the suspended particles. Similarly, the dielectric barrier discharge (DBD) system produces ultra violet light and hydrogen peroxide within the plasma zone which is not fully maximised for the mineralization of persistent organic pollutants. Rapid oxidation and aggregation of nano zero valent iron particles in photo-Fentons process reduce the particles mobility and affect its performance. In the same vein, the jet loop reactor (JLR) system is characterised by low impingement yield, which is responsible for low mineralization rate. In light of this background, this research investigated the degradation of bisphenol-A and 2- nitrophenol in aqueous solution using the following combined advanced oxidation methods: DBD/supported TiO₂ or Ag doped TiO₂ photocatalysts, DBD/photo-Fenton induced process and JLR/UV/H₂O₂. The target was to assess the performance of each single system and then identify the best combined AOTs capable of significantly mineralizing the target compounds. Firstly, two materials were developed namely supported TiO₂ and stabilized nano zero valent Fe. The TiO₂ photocatalyst supported on a stainless steel mesh was synthesised using sol-gel solution of 8 % PAN/DMF/TiCl₄. The influence of calcination temperature and holding time on the formation of nanocrystals was investigated. Afterwards, various amounts of metallic silver were deposited on the (optimum) supported TiO₂ photocatalyst using thermal evaporation. The catalysts were characterized by several analytical methods; HRSEM, HRTEM, EDS, SAED, FTIR, TGA-DSC, UV-vis/diffuse reflectance spectroscopy, XRD, BET, and XPS. The photocatalytic activity of the prepared catalysts was determined using methylene blue as a model pollutant under ultra-violet light irradiation. Secondly, the TiO2 photocatalyst and 2.4 % Ag doped TiO₂ nanocomposites obtained as optimums (in section 1) were combined with the DBD to decompose BPA or 2-NP in aqueous solution. Moreover, the photo-Fenton process was applied for degradation of the model pollutants, and different dosages of stabilized nZVI (in the range of 0.02 -1.00 g) were added to the DBD system to induce the photo-Fenton process and improve BPA or 2-NP degradation efficiency. Finally, a jet loop reactor (JLR) presenting advanced mixing by the “impinging effect” was explored to decompose BPA or 2-NP in aqueous solution as a function of inlet applied pressure, solution pH, and initial concentration of BPA or 2-NP. Subsequently, different concentrations of hydrogen peroxide (H₂O₂) were added to the JLR to enhance the mineralization process. Furthermore, a combination of JLR with in-line UV light and H₂O₂ were further utilised to decompose BPA or 2-NP in aqueous solution. The residual concentration of the model compounds and intermediates were analysed using high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LCMS). The concentration of the ozone, hydrogen peroxide and hydroxyl radicals generated by the DBD in the presence or absence of a catalyst was monitored using Ultraviolet-visible spectroscopy and Photoluminescence spectroscopy. The results revealed that the optimal thermal conditions to obtain well supported uniformly grown, highly active crystalline TiO₂ catalysts with high specific surface area was 350 ºC at a 3 h holding time in N2 atmosphere with a flow rate of 20 mL/min. Pyrolysis temperature and holding time played an important role on the crystalline nature and photocatalytic activity of the catalyst. Moreover, 2.4 % Ag doped TiO₂ nanocomposites exhibited higher photocatalytic activity for methylene blue degradation than the undoped supported TiO₂ nanocrystals. The results indicated that combining DBD with 2.4 % Ag doped TiO₂ nanocomposites achieved 89 % and 81 % removal efficiency for BPA or 2-NP compared to 67.22 % or 56.8 % obtain when using the DBD system alone. The 2.4 % Ag doped TiO₂ nanocomposites demonstrated excellent activity and offered photochemical stability after four repeated applications.In the case of the photo-Fenton induced process, nano zero valent iron particles (nZVI) stabilized with polyethylene glycol were synthesised using a modified borohydride reduction method. The HRSEM, BET, XRD, and XPS analysis confirmed the formation of filamentous, high surface area iron nanoparticles in the zero valent state. Unlike combined DBD/Ag doped TiO2 nanocomposites, 100 % or complete removal of BPA or 2-NP in aqueous solution was achieved with DBD/nZVI system within 30 minutes compared to 67.9 % (BPA) or 56.8 % (2-NP) with DBD alone after 80 minutes. The removal efficiency was attributable to the production of an increased concentration of OH radicals as well as existence of a synergetic effect in the combined DBD/nZVI system. Five new transformation products namely: 4-nitrophenol (C₆H₅NO₃), 4-nitrosophenolate (C₆H₄NO₂), 4-(prop-1-en-2-yl) cyclohexa-3,5-diene-1,2-dione, (C₉H₈O₂), 4-(2- hydroxylpropan-2-yl)cyclohexane-3,5-diene-1,2-dione (C₉H₁₀O₃), and 1,2-dimethyl-4-(2- nitropropan-2-yl)benzene (C₉H₁₀NO₄) were identified during the degradation of BPA. While, three aromatic intermediate compounds such as 2-nitro-1,3,5-benzenetriolate (C₆H₂NO₅), 2- nitro-1,4-benzoquinone (C₆H₃NO₄), and 2,5-dihydroxyl-1,4-benzoquinone (C₆H₄O₄) respectively were identified during the degradation of 2-NP for the first time in the DBD with JT14 or JT17 using LC-MS. These intermediate compounds have never been reported in the literature, thereby expanding the number of BPA or 2-NP intermediates in the data base in the DBD/JT14 or DBD/nZVI system. BPA degradation proceeded via ozonation, hydroxylation, dimerization, and decarboxylation and nitration step, while 2-NP proceeded via hydroxylation, nitration and denitration respectively. Furthermore, maximum removal efficiency of BPA or 2-NP in aqueous solution using JLR alone under the optimum solution pH (3), inlet pressure (4 bar), flow rate (0.0007 m3/s) was 14.0 % and 13.2 % respectively after 80 minutes. A removal efficiency of 34.9 % was recorded for BPA while 33.2 % was achieved for 2-NP using combined JLR/UV under the same conditions as JLR alone. For the combined JLR/H₂O₂ under optimum conditions of inlet pressure (4 bar), solution pH (3) and peroxide dosage (0.34 g/L), a 51.3 % and 50.1 % removal efficiency was achieved for BPA and 2-NP respectively under same conditions relative to JLR alone. Combination of JLR/UV/H₂O₂ achieved 77.7 % (BPA) or 76.6 % (2- NP) removal efficiency under the same conditions. The combined JLR/UV/H₂O₂ process was found to be most effective combination under the optimized operating parameters due to existence of a synergetic index value of 6.42 or 6.84. This implies that JLR should be coupled with UV and H₂O₂ to achieve greater mineralization efficiency instead of using the system individually. The obtained experimental data of these combined treatment processes fitted the pseudo-first order kinetic models. The combination of the JLR/UV/H₂O₂ was found to be energy efficient and could effectively degrade BPA or 2-NP in aqueous solution to a greater extent than the JLR, JLR/UV or JLR/H₂O₂ system. However, the total organic carbon (TOC) reduction value by all combined DBD and JLR system recorded was not completely achieved due to the formation of recalcitrant intermediate compounds under the applied conditions. In conclusion, this study is reporting for the first time a combination of supported 2.4 % Ag doped TiO₂ nanocomposites with dielectric barrier discharge system for BPA/2-NP degradation in aqueous solution; a combination jet loop reactor based on impingement with in-line UV lamp and H2O2 for successfully decomposing BPA or 2-NP in aqueous solution; as well as a combination of dielectric barrier discharge system and stabilised nano zero valent iron particles, which induced a photo-Fenton process for highly effective removal of BPA or 2-NP in aqueous solution. This study conclusively supports the hypothesis that combined advanced oxidation technologies offer a sustainable and highly efficient means of achieving partial or complete removal of BPA or 2-NP in aqueous solutions. Considering all the combinations of AOTs investigated in this study, the novel DBD/photo-Fenton-induced process under optimised operating parameters was found to be the most efficient in the elimination of BPA or 2-NP in aqueous solutions. The combination of DBD with photo- Fenton like process offers a promising advanced waste water purification technology in the immediate future. Based on these findings, it is recommended that DBD should be redesigned to prevent loss of ozone and JLR system reconfigured to increase impingement and cavitational yield in order to have an effective combination treatment strategy for waste water purification especially in large scale waste water management. / National Research Foundation (NRF) and Water Research Commission, South Africa

Deposition of noble metal and semiconductor nanocrystalline thin films has received much attention. CdS and CdSe are important semiconductors used in optical devices. A wet chemical route which uses the interface of two immiscible liquids to control the growth and deposition of nanocrystalline thin films forms the basis of the current study. In this method, a metal precursor dissolved in toluene or decane is held in contact with a water layer containing a reducing or sulphiding agent. The reaction proceeds at the interface of the liquids and results in deposits adhering to the interfacial region. The products of such reactions typically consist of nanocrystals forming a thin film. Stable sols of Au, Ag were found to metathesize on contact with alkylamine in oil to form monolayer films that spread across large areas at the water/oil interface. The nature and properties of interfacial thin films depend on the alkylamine. Nanocrystalline thin films consisting of CdS adhering to the interface starting with a polydispersed aqueous sol of crystallites and alkylamine were obtained. The optical band gaps of the films formed are dependent on the alkylamine chain length, with the shortest chain yielding the largest gap. A systematic increase in particle diameters following adsorption is responsible for changes in the electronic structure of films. The formation of nanocrystalline films of CdS adhering at the interface using a toluene solution of cadmium diethyldithiocarbamate and aqueous Na2S solution, in the presence of tetraoctylammonium bromide (TOAB) in the aqueous phase, was investigated under various reaction parameters, while CdSe was obtained using Na2SeSO3 solution and the influences of deposition temperature and solution concentration were studied. A ternary water/decane/2-butoxyethanol /salt system was used to grow deposits of CdSe and CdS. Nanostructured thin films were obtained at the upper interface of the ternary system, between the emulsive middle layer and oil rich top phase. The influence of deposition conditions such as precursor concentrations and temperature, as well as the nature of the medium on the properties of the deposits was studied. Deposits grown using the ternary system were compared with those obtained using water/decane and water/toluene systems. Reaction parameters such as temperature, solution concentration and the size of CdS and CdSe were controlled. A thin film of CdS and CdSe nanocrystals was formed at the interface. The grain size was found to be dependent on reaction temperature and solution concentration, with higher temperatures and solution concentration resulting in larger grains. The nature of thin films obtained at the interface of two immiscible liquids and of a water/decane/2-butoxyethanol/salt ternary system were studied using Scanning and Transmission electron microscopy, X-ray diffraction and UV-visible spectroscopy.

The thesis deals with Corporate Social Responsibility (CSR). Theoretic part is focused on themes of sustainable development and corporate social responsibility. The focus is concentrated on G3 Standard of Global Reporting Initiative, that is used to make CSR report of Commerzbank AG in practical part. Fundamental part pays attention to chart Commerzbank AGs'activities in corporate social responsibility and improvement proposals.

The thesis is concerned with a question, what plays the key role in decision making process about restructuring of production capacities of automotive companies within global process. All of this is running in the background of optimization factors influencing their cost items value. Volkswagen AG, more precisely SKODA AUTO was chosen for behavior analysis introduced as a case study. The goal is to suggest some recommendations for SKODA AUTO to help with achieving sales of 1,5 million cars in 2018 based on global pressures analysis affecting automotive industry and future cost development study in this field. The main benefit of the thesis is the complex cost items analysis resulting in application of the conclusions into SKODA AUTO case in a form of recommendations based on cost reduction.

The main goal of this thesis is to properly apply the methods and approaches of these two concepts of valuing stocks. Fundamental and technical analysis are the most common ways to value stocks. In the first part of the text, I present the theoretical background of fundamental analysis and aftewards apply its methods in practice. The whole analysis comes from global analysis of the economy and its relations to capital markets to banking industry analysis and firm analysis in the end. Technical analysis comprises two basic fields - charting and technical indicators. Upon the practical application of both concepts, I present the final recommendation for investors.

Il est aujourd’hui bien établi que les amibes libres jouent le rôle de vecteurs à la bactérie pathogène Legionella pneumophila favorisant ainsi son développement et sa propagation dans l’environnement. Ainsi, et jusqu’à maintenant, toutes les espèces d’amibes libres étudiées ont démontré une capacité à soutenir et favoriser la croissance de la bactérie responsable des légionelloses. Toutefois, l’ensemble des études a porté sur un nombre restreint d’espèces amibiennes, et leurs capacités relatives à soutenir la croissance bactérienne n’ont que très peu été abordées. Nous avons comparé la capacité de différentes espèces amibiennes à soutenir la prolifération de différentes souches de L. pneumophila du sérogroupe 1. Ces études ont mis en évidence les propriétés particulières d’une souche d’amibe appartenant à l’espèce Willaertia magna. Cette souche présente, au contraire de toutes les autres espèces, la capacité à inhiber et diminuer la prolifération de certaines souches de L. pneumophila. Nous avons par ailleurs pu démontrer l’existence d’une phagocytose interamibienne entre différentes espèces d’amibes, un phénomène jamais mis en évidence à notre connaissance. Les conséquences de cette phagocytose interamibienne sur la croissance et la prolifération de L. pneumophila sont aussi rapportées. La microscopie électronique suggère fortement que la bactérie L. pneumophila ne peut inhiber la fusion phagolysosomale chez W. magna à l’inverse du phénomène observé chez les espèces amibiennes permissives. Ces observations démontrent l’importance de phénomènes membranaires dans la capacité des bactéries à parasiter leur hôte amibien. L’analyse comparée de la composition lipidique des membranes de différentes espèces amibiennes montre chez W. magna une expression élevée de phosphatidylcholine. L’inhibition de la voie de biosynthèse de ce phospholipide par méthylation de phosphatidyléthanolamine résulte en une forte diminution de la croissance amibienne, suggérant que cette voie métabolique joue un rôle important dans les capacités de résistance de W. magna / Free living amoeba is a known vector of L. pneumophila in the environment and it has been shown to favour bacterial growth. Until now, all studied amoeba species showed a capacity to support the growth of the bacterium responsible for the Legionnaire’s disorder. However, these studies were related to a restricted number of amoebic species, and their relative capacity to support the bacterial growth. We compared the capacity of various amoebic species to support the proliferation of various strains of L. pneumophila. These studies highlighted the particular properties of a strain belonging to the Willaertia magna species. This amoeba has, contrary to all the other species, the capacity to inhibit and decrease L. pneumophila proliferation. We also demonstrate the existence of an inter-amoebic phagocytosis between various species of amoebas, a phenomenon never studied to our knowledge. The consequences of this inter-amoebic phagocytosis on the growth and proliferation of L. pneumophila are also reported. Electron microscopy strongly suggests that the bacterium cannot inhibit the phagolysosomal fusion in W. magna contrary to permissive amoebic species. These observations suggest the importance of membrane phenomena in the capacity of the bacteria to infest their amoebic host. Compared analysis of the lipidic composition of various amoebic species shows in W. magna a high expression of phosphatidylcholine the major phospholipid. The inhibition of the PE N-methyltransferase biosynthesis pathway of this phospholipid results in a strong reduction of the amoebic growth, suggesting that this metabolic pathway plays an important role in the resistance capacity of W. magna to L.pneumophila.

Rapid development processes and higher customer requirements lead to increasing integration of software solutions in the automotive industry’s products. Today, several electronic control units communicate by bus systems like CAN and provide computation of complex algorithms. This increasingly requires a controlled timing behavior. The following diploma thesis investigates how the timing analysis tool SymTA/S can be used in the software development process of the ZF Friedrichshafen AG.Within the scope of several scenarios, the benefits of using it, the difficulties in using it and the questions that can not be answered by the timing analysis tool are examined. (new: additional files)

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