Alors que le début de la crise de l'euro a relancé le débat sur l’interdépendance du risque decrédit et la relation dette bancaire-dette souveraine, l’importance du secteur réel est négligéedans l’élaboration des mesures de relance de la croissance économique dans la zone euro. Cettethèse se concentre sur ces questions au sein de la zone euro. D’abord, nous évaluons les effets«spillover» de la crise souveraine sur le coût de crédit des entreprises non financières enprésence des mesures d’austérité (Chapitre-I). Nos résultats indiquent un effet significatif de ladette publique sur le coût des prêts. En outre, en période de crise, les mesures d’austéritéimpactent significativement le coût de crédit tandis qu’avant la crise, on note une petite illustrationde la demande agrégée de Keynes. Ensuite, nous montrons que les fonctions traditionnelles desbanques, notamment celle de création de liquidité fragilisent le secteur souverain (Chapitre-II). Enparticulier, nous montrons que le risque de liquidité des banques agit comme un canal depropagation de l'incertitude vers les sociétés non financières et inversement. Enfin, nousexaminons la dynamique du risque de crédit sur la dette souveraine, les entreprises et lesbanques (Chapitre-III). Nos résultats montrent qu’il existe un risque de contagion sur les secteurset les marchés financiers de l’union monétaire. Par ailleurs, les résultats des simulations dechocs de primes de risque des pays «noyaux» de la zone euro confirment l’existence d’effetsindirects sur le reste de la zone. De plus, nous constatons un phénomène de fuite desinvestisseurs vers les valeurs refuges. / The onset of euro crisis has rekindled the policy debate regarding credit risk interdependenceamong sovereign-bank nexus. In this vein, the importance of real sector is overlooked whileformulating corrective measures for the recovery of economic growth in EMU. This thesispresents a study that examined these issues in euro zone. First, we evaluate spillover effect ofeuro crisis on borrowing cost of non-financial firms in presence of austerity measures (Chapter-I).Our results suggest significant effect especially where creditor rights protection are weak. Inaddition during recent crisis, results indicate presence of credibility channel due to austeritymeasures whereas; there is slight indication of aggregate demand channel before crisis. Second,we find traditional function of bank’s liquidity creation as a significant conduit of sovereign distressto real sector (Chapter-II). Particularly, our main finding shows that bank liquidity risk acts as aconduit which propagates uncertainty towards non-financial firms and re-channels it back torespective government. Finally, we examine cross-market credit risk dynamics among sovereignbank-firm nexus to identify presence of contagion during euro crisis period (Chapter-III). Ourresults report grave evidence of credit risk contagion across sectors and member states incorresponding financial markets in EMU. Moreover like peripheral countries, simulation results toshock in core countries risk premia strongly provide evidence of contagion towards remainingeuro zone.

A partir d’une analyse du défaut des banques et de la régulation au travers des notations de crédits (et des agences de notation), des modèles portant sur les CDS, de Bâle III et du capital insurance, nous trouvons que les spécificités des CDS en font un bon candidat pour prévoir (et idéalement empêcher) les défauts potentiels des banques. En effet, grâce aux propriétés (financières et économiques) des CDS, ainsi qu’aux résultats d’études empiriques, nous montrons qu’ils reflètent correctement le comportement des risques des banques et qu’ils ont capté les changements informationnels plus rapidement que les notations de crédits qui sont restées relativement constantes durant 2007 et 2008.Ainsi, en utilisant un déclencheur ad hoc basé sur les CDS et l’action appropriée si le déclencheur venait à s’activer, nous pourrions empêcher le défaut d’une banque. Et la compréhension du mécanisme afférent au capital contingent est d’un grand intérêt pour atteindre cet objectif qui optimise le monitoring mis en oeuvre par les banques et les régulateurs. / Based on an analysis of the default of the banks and regulation through credit ratings (and rating agencies), CDS models, Basel III, bail-In and capital insurance, we find that the characteristics of CDS make them a good candidate to forecast (and ideally prevent) the potential defaults of the banks. Indeed, thanks to the economics of CDS and results of empirical studies, we show that they are a good proxy of bank risks and that they did capture information changes more quickly than the credit ratings which remained relatively constant during 2007 and 2008.So, using a specific trigger based on CDS and the appropriate action, should the trigger be activated, we could prevent the default of a bank. And the understanding of contingent capital mechanism is of great interest to reach this objective which optimizes the monitoring implemented by banks as well as regulators.

The technology of semiconductor-based photocatalytic water splitting to produce hydrogen using solar energy has been considered as one of the most important approaches to solve the world energy crisis. Therefore, the development of the effective semiconductor photocatalysts has undergone considerable research. However, the traditional photocatalysts suffer from the negative effects from rapid charge recombination, which reduces the excited charges by emitting light or generating phonons. Efficient charge separation and fast charge transport, avoiding any bulk/surface recombination, are fundamentally important for photocatalytic hydrogen generation through water splitting. Here, we have introduced assembled layered materials as photocatalyst systems with their unique physicochemical properties to realize the effective charge separation and high photocatalytic activity. Using graphene as a two-dimensional supporting matrix, we have succeeded in selective anchoring of semiconductor and metal nanoparticles as separate catalytically active sites on the graphene surface. The ability of graphene to capture, transfer and store electrons and its potential to serve as a conductive support are demonstrated. The TiO₂ semiconductor/metals nanocrystals-graphene ensemble makes it possible to carry out selective catalytic processes at the separate sites and provides the potentials for applications in water splitting reactions. After demonstrating the positive role of graphene in such photocatalytic system, we then fabricate a simple but highly cooperative ensemble with CdS and MoS₂ nanocrystals dispersed on graphene sheets. It is demonstrated that CdS nanocrystals can also capture visible light energy and facilitate excited electron transfer to MoS₂ (as metal substituent) for catalytic hydrogen production via the 2-D graphene which plays a key role as an efficient electron mediator. Hexagonal multilayer MoS₂ with a layered structure in this system serves to provide active sites for hydrogen evolution by its exposed Mo edges. Hence, multilayer MoS₂ is an ideal cocatalyst of semiconductors for hydrogen generation. This crystalline-layered structure also shows semiconducting properties, however, its characteristic indirect band gap displays a poor light capture and emission ability with excited electrons and holes with different momentum. In contrast, single layer MoS₂ shows a direct band gap behavior. Our studies have clearly shown that single layer MoS₂ prepared with lithium intercalation indeed displays encouraging results in hydrogen evolution due to the direct band gap and quantum confinement effects. In addition, the exfoliated single layer MoS₂ exhibits extraordinary enhanced activity and stability in combination with the Eosin Y sensitized system when compared to those of multilayer MoS₂ and bulk MoS₂ counterparts, which is attributed to the improvement of the density of surface active sites with stronger adsorption for the Eosin Y molecules on the single layer MoS₂. In addition, this multifunctional catalyst on graphene sheet can also create adsorption sites on a defective basal surface of single layer MoS₂ through adsorption of Eosin Y where electron transfer from photoexcited Eosin Y molecule to graphene via the 2-D MoS₂ mainly takes place. Thus, the photo-generated electrons are then effectively transported to the exposed active sites of MoS₂ for the proton reduction to hydrogen molecule. It is believed the above novel assembled molecular layered systems may be applicable for a wide range of catalytic,photocatalytic and electrocatalytic reactions.

The aim of the thesis is to investigate determinants of corporate bond and CDS contract pricing using a sample of 34 European companies over the period 2008-2014. This work extends existing literature by studying differences in determinants of bond and CDS spreads not only for different time periods, but also for different sets of companies grouped by geography, industry, and profitability. The results reveal that bond and CDS spreads are generally influenced by similar factors, with a company's credit rating being the most influential factor. Nevertheless, the investigation of time-specific estimations suggests that firm-specific factors play a more significant role in pricing bonds, whereas market factors have a higher impact on CDS spreads. The analysis of the subsamples reveals substantial differences in regression results for individual groups of companies, which suggests a presence of idiosyncratic factors. Our conclusion is that the pricing of bonds and CDS contracts is not only time-dependent, but also unique for different groups of companies, which implies a necessity to use different pricing models for individual contracts.

O clássico Equilíbrio Econômico nunca foi realidade, especialmente após as primeiras crises dos mercados financeiros. Hoje se sabe que as economias estão longe da situação de equilíbrio, sendo vistas mais como um processo em construção do que um estado estático propriamente dito. Se assemelham a um sistema estocástico, e não determinístico como um dia se pensou. O Brasil é um país jovem, e seus sistemas econômico e político ainda estão em formação. Tendo em vista todas as mudanças e crises que o país tem sofrido em sua história recente, este estudo busca uma forma alternativa para que tais eventos possam ser detectados e, principalmente, de certa forma antecipados, para que as providências cabíveis possam ser tomadas a tempo de se evitar grandes perdas financeiras. Para tal, as medidas de Complexidade de SDL e LMC são aplicadas às séries do câmbio dolar-real, Ibovespa e CDS Brasil e avaliadas durante eventos de crises. Detectados os principais eventos de cada série, \"volta-se no tempo\", ao início da crise, e avalia-se, dada a informação disponível naquele momento, a possibilidade de se detectar a crise em seus primeiros estágios. Ao fim, conclui-se que as Medidas de Complexidade LMC e SDL são robustas na detecção de aumentos de volatilidade nos dados de séries financeiras. Assim sendo, apresentam grande potencial como indicadores precoces de crises financeiras. Para tal, não são necessários cálculos extensivos, nem grandes históricos de dados; e também não são necessárias hipóteses sobre a distribuição de probabilidades destes dados. Acredita-se que este seja o primeiro passo em direção à construção de um monitor de crises em tempo real. / The classical Economic Equilibrium has never been a reality, especially after the first financial markets crisis events. It is known nowadays that economies are far from their Equilibrium, they are seen more as a process under construction, not a static state; a stochastic instead of deterministic process, as it was thought before. Brazil is a young country, hence its economic and political systems are still maturing. In light of all the changes and crises it has been suffering in the recent history, this research seeks for an alternative mechanism to detect and anticipate these crisis events, in order to avoid massive financial losses. To this end, the LMC and SDL Complexity Measures are applied to the Dollar-Real exchange rates, Ibovespa and Brazilian CDS time series during crisis events. After detecting the main events, the idea is to \"turn back in time\", to the events\' inception, and analyse if, given the limited amount of information on that time, the crises could be detected on their early stages. Finally, this research concludes that both LMC and SDL Complexity Measures are robust in detecting volatility increases on the financial series, revealing good potential as crises early warning. However, no extensive calculus, large samples, or strong assumptions about the data probability distributions are needed to this aim. Therefore, these results represent the very first step towards a crises real time monitor.

In this work we investigated fabrication of semiconductor nanomaterials and evaluated their potential for photo-chemical and photovoltaic applications. We investigated different II-VI semiconductor nanomaterial systems; (i) ZnO oriented nanowire arrays non-epitaxially grown from a substrate; and (ii) colloidal CdE (E=Te,Se,S) quantum structures synthesized by solution-based thermal decomposition of organo-metallic precursors. We have studied the synthesis of vertically aligned ZnO nanowire arrays (NWA), by a wet chemical process on various substrates. We have extended this method wherein nanofibers of poly-L-lactide act as a substrate for the radially oriented growth of ZnO nanowires. By combining the large surface area and the flexibility of the PLLA-ZnO hierarchical nanostructure we have shown the proof-of-principle demonstration of a ‘continuous-flow’ water treatment system to decompose known organic pollutants in water, as well as render common waterborne bacteria non-viable. We have studied synthesis of colloidal quantum dots (QD), and show size, morphology and composition tailored nanocrystals for CdE (E=S, Se, Te) compositions. We have studied the influence of crystal growth habits of the nanocrtsyals on the final morphology. Furthermore we have synthesized core-shell, CdSe-CdS QDs with spherical and tetrahedral morphologies by varying the reaction conditions. We show that these core-shell quantum dots show quasi-type II characteristics, and demonstrate with I-V measurements, the spatial localization of the charge carriers in these hetero-nanocrystals. For this purpose, we developed hybrid materials consisting of the core-shell quantum dots with electron acceptors (ZnO nanowires) and hole acceptors (polymeric P3HT nanofibers). In addition we have also compared the synthesis reaction when carried out with conventional heating and microwave-mediated heating. We find that the reaction is enhanced, and the yield is qualitatively better when using microwave induced heating. / QC 20120525

The research presented has been focused on understanding the surface effects on the optical and electronic properties of some metallic and semiconductor nanomaterials. When the particle sizes are on the nanometer length scale, a large fraction of atoms in the particles are on the surface. The bonding of the surface atoms being unsaturated could cause trapping and introduce defects that interact with the excited electrons. The effect of the surface on the optical and electronic properties of some semiconductor and metallic nanoparticles is investigated. When the size and shape of nanomaterials change, both the electron density of the excited electrons on the surface and the electronic structure change. Therefore, it becomes important to understand how these changes affect the electronic motion in the particles in order to exploit their full potential in a variety of applications. Semiconductor nanoparticles studied include cadmium selenide (CdSe) and cadmium sulfide (CdS). Effect of changing CdSe shape and size on optical and electronic properties has been investigated and the ability for the CdS nanoparticles to show optical gain (stimulated emission) in solution at room temperature is reported. Effect of surface phonon contribution on the exited electron relaxation in copper nanoparticles is investigated. For the particles size smaller than the mean free path of the electrons in the metal, electron-surface phonon coupling becomes an important factor (contribution) for hot electron relaxation. In the thesis presented, it is shown for the first time the size depended electronic relaxation in copper nanoparticles. Fluorescence due to surface plasmon field enhancement is observed for copper nanoparticles to be million times stronger than the fluorescence observed from bulk copper.

This work focuses on the solar cell based on the heterostructure formed between Copper Phthalocyanine (CuPc) and Cadmium Sulfide (CdS). Two different fabrication techniques were used for depositing the organic and inorganic layers of CuPc and CdS layers respectively. CuPc was deposited by electrodeposition while CdS was deposited by chemical bath deposition. Hybrid CdS/CuPc thin films were obtained from CdS films grown on Glass/ITO by chemical bath deposition followed by electrodeposition of CuPc onto these films and annealing at 250˚C after the deposition of each layer. The maximum open circuit voltage (Voc) and the short circuit current density (Jsc) obtained for this heterojunction solar cell are 0.59v and 0.7mA/cm2 respectively and these are the highest values achieved in literature till date. The materials characteristics and electrical performances of the device were analyzed. The effect of increasing the thickness of CuPc and CdS on the short circuit current density and open circuit voltage were also investigated.

La compréhension des propriétés électriques de nano-objets est essentielle pour le développement s des nanotechnologies. La microscopie à force Kelvin (KFM) est une des techniques les plus utiles pour cartographier simultanément la topographie et la différence de potentiel de contact (CPD) à l'échelle nanométrique. Après 20 ans de développement, la KFM est principalement utilisé dans des conditions normales de pression et de température, permettant d'effectuer, de manière simple, de multiples analyses comparatives. Toutefois, sous ultra-vide (UHV), comme la surface est contrôlée et que la sensibilité est meilleure, des mesures plus précises et plus fiables sont réalisables. Dans la première partie, la mesure KFM sous atmosphère ambiante est améliorée en développant la technique simple-passage à la fois en modulation de fréquence (FM) et en modulation d'amplitude (AM). Une électronique externe Nanonis a été adaptée sur les AFMs commerciaux (Dimension 3100 et MultiMode, Bruker). Une étude comparative avec le mode Lift a été réalisée sur des couches de graphène épitaxié sur échantillon de SiC. L'effet de la distance pointe-échantillon sur le contraste et la résolution est décrit ainsi que l'influence des paramètres expérimentaux. Une amélioration significative du contraste et de la résolution est clairement observée sur les résultats obtenus par la technique simple passage en modulation de fréquence, indépendamment de la distance pointe-échantillon. Dans une deuxième partie, la technique KFM est développée sous vide secondaire. Le travail instrumental est réalisé sur un AFM EnviroScope de chez Bruker, qui a été équipé d'une électronique externe Nanonis, permettant de mesurer simultanément la topographie en mode non-contact et la CPD en modulation d'amplitude ou de fréquence. Les résultats montrent que la CPD mesurée est comparable à celle obtenue avec une mesure sous ultravide. Enfin, après avoir posé les bases à la fois expérimentale et théorique de la KFM, cette technique est utilisée pour caractériser les hétérostructures CdTe/CdS en films minces utilisés pour les applications de cellules solaires. Un protocole de préparation d'échantillon sur la tranche a été spécialement développé. L'hétérojonction CdTe/CdS est étudiée sous polarisation à la fois dans l'obscurité et sous éclairement. L'influence de l'épaisseur de la couche de CdS est également étudiée pour comprendre son effet dramatique sur le rendement des cellules solaires.

Most farmers in South Africa use standard insurance to protect their crops against natural disasters such as hail or strong winds. However, no South African insurance contracts exist to compensate for too much or too little rain (although floods are covered), or which will pay out if temperatures were too high or too low for a certain period of time for the relevant crop. Weather derivatives - which farmers may employ to ensure crops against adverse temperatures - do exist, but these are mostly available in foreign markets in the form of Heating Degree Days contracts and Cooling Degree Day contracts and are used chiefly by energy companies. Some South African over-the-counter weather derivatives are available, but trading in these is rare and seldom used. The goal of this dissertation is to establish a pricing equation for weather derivatives specifically for use in the South African market. This equation will be derived using a similar methodology to that employed for credit default swaps. The premium derived will be designed to compensate grape farmers from losses arising from two different climatic outcomes - in this case temperature and precipitation. These derivatives will be region and crop specific and the formulation will be sufficiently flexible as to allow for further climatic possibilities (which may be added at a later stage). These weather derivative premiums will then be compared to standard crop insurance to establish economic viability of the products and recommendations will be made regarding their usage. The possibility of the simultaneous use of these derivatives and standard crop insurance for optimal crop coverage will also be explored and discussed. / Thesis (M.Com. (Risk management))--North-West University, Potchefstroom Campus, 2011.