Ce travail montre la mise en œuvre d'une technique originale pour le chauffage rapide et bien contrôlé de catalyseurs sous forme de films minces déposés sur un structurant métallique. L'utilisation d'un système à induction électromagnétique adapté à un réacteur catalytique de type annulaire nous a permis d'étudier un certain nombre de matériaux catalytiques, déposés sur acier inoxydable, dans une perspective d'oxydation totale en CO2 et H2O de composés organiques volatiles (COV) présents dans l'air. La combustion de l'isopropanol et du toluène par l'oxygène de l'air a été étudiée en utilisant différents catalyseurs déposés sous forme de films minces: 1%Pt/Al2O3, 0,3%Pt/SnO2, 1%Pt/SnO2 et 1%Pt/YSZ. Les solides ont été préparés par imprégnation des oxydes correspondants par H2PtCl6 puis ont été déposés sur le support d'acier inoxydable par électrophorèse. Les principaux paramètres relatifs au mode de chauffage ont été étudiés de même que l'influence sur la conversion des COV de différents facteurs tels que la quantité de catalyseur, le pourcentage de platine ou la nature du support oxyde employé. Les informations fournies par ce système innovant ont également été comparées pour validation à celles obtenues à l'aide d'un système classique (microréacteur en quartz à lit traversé chauffé de manière conventionnelle) pour une réaction de référence qui est l'oxydation de CO en CO2. Le système décrit dans cette étude présente d'une part un intérêt pratique pour le traitement rapide de contaminations accidentelles de l'air ambiant, mais est aussi un très bon moyen d'obtenir des paramètres cinétiques fiables dans le domaine des catalyseurs en films minces utilisés dans de nombreux réacteurs structurés / This study shows the development of an innovative technique for a fast and well-controlled heating of catalysts deposited as thin films on a metallic support. The use of an electromagnetic induction system fitted to an annular catalytic reactor enabled us to study some catalytic materials deposited on stainless steel. The target application was the abatement of volatile organic compounds (VOCs) in the air. Isopropyl alcohol and toluene combustion by the oxygen was studied on various thin films catalysts, i.e. : 1%Pt/Al2O3, 0,3%Pt/SnO2, 1%Pt/SnO2 et 1%Pt/YSZ. Solids were prepared by wet impregnation of the corresponding oxides by H2PtCl6 and were deposited on the stainless steel support using an electrophoretic deposition technique. The main parameters of the heating system were investigated as well as the influence on VOCs abatement of various parameters such as the thickness of catalyst film, the platinum amount and the nature of the oxide. For validation purpose, the data provided by this innovative system were also compared to the ones provided by a classical one (quartz plug-through microreactor heated in a conventional way) in a reference reaction which was CO oxidation into CO2. The system described in this study shows on the one hand a real practical interest for fast remediation of indoor air polluted by VOCs, and on the other hand is a very powerful tool for obtaining kinetic data about thin layer catalysts used in many structured reactors

Ces dernières années, les besoins en électronique de puissance s’orientent vers la miniaturisation globale des cartes électroniques, parallèlement à une augmentation des puissances de travail. C’est dans ce contexte que s’inscrivent les travaux de cette thèse, principalement axée sur l’élaboration, l’amélioration des performances et l’intégration de composants passifs (inductances, transformateurs…) en électronique de puissance.Les matériaux choisis pour remplir les fonctions magnétiques de ces composants dans leurs conditions de travail sont les ferrites NixZn1-xFe2O4 (0<x<1). Du cuivre est ajouté pour diminuer la température de frittage, de plus de 1200 °C à moins de 950°C, permettant le cofrittage avec un métal conducteur, et du cobalt pour diminuer les pertes totales en puissance du ferrite formé. La formulation finale devient alors (NixZnyCuz)1-εCoεFe2-δO4 (x+y+z=1). Enfin, de l’oxyde de bismuth Bi2O3 est ajouté comme fondant pour abaisser encore la température de frittage et éviter les problèmes de diffusion.Après une étude bibliographique, les travaux se sont orientés selon différents axes. Il s’agissait tout d’abord d’optimiser la formulation du ferrite pour élaborer des échantillons aux propriétés électromagnétiques et physicochimiques ciblées. Cet axe de travail regroupe de nombreuses études sur la formulation des ferrites Ni-Zn-Cu-Co, parmi lesquelles les principales sont l’étude de l’influence de la stœchiométrie en fer, du rapport Ni/Zn dans la formulation et du procédé d’ajout de cobalt selon son taux. Ces travaux ont permis de mettre en évidence qu’un léger défaut de fer maîtrisé (~Fe1,98) pouvait améliorer les propriétés et les performances de ces ferrites. L’étude de l’influence du rapport Ni/Zn a permis la réalisation de ferrites à perméabilités très faibles, de 40 à 135, et aux bonnes performances en puissance. Les résultats de cette étude ont été publiés dans le Journal of the Japan Society of Powder and Metallurgy. Tout au long de la thèse, l’élaboration d’échantillons céramiques, base incontournable de chaque étude, a été réalisé au laboratoire, comme la plupart des tests et caractérisations. Ces derniers peuvent être microstructuraux et physicochimiques (DRX, MEB, BET, ATD/ATG…), ou électromagnétiques (mesures d’aimantation, de perméabilité, de pertes en puissances, etc…).La finalité de ces travaux étant l’intégration de puissance, cette dernière représente le second axe majeur, et regroupe également de nombreuses études, parmi lesquelles les principales sont les études des influences du bobinage sur les pertes d’un composant de type inductance et de l’entrefer (espacement amagnétique au sein du circuit magnétique), classiquement utilisé pour diminuer la perméabilité apparente, non sans conséquence sur les performances en puissance. Une campagne de mesures de pertes totales a également été réalisée dans l’objectif de dégager des lois comportementales sur la variation de ces pertes en puissance et en fréquence.Tous ces travaux et leurs résultats sur le matériau ferrite, son utilisation en électronique de puissance, et une bonne maîtrise du procédé d’élaboration (notamment multicouche), ont permis la réalisation de microcomposants passifs intégrables, aux propriétés ciblées et aux très bonnes performances (pertes diminuées d’un facteur 6 à 10 par rapport au commerce). / In recent years, power electronics needs are moving towards the global miniaturization of electronic boards, and an increase of the working powers. The works performed during this thesis, mostly oriented on the elaboration, the performances improvement and the integration of passive components (inductors, transformers…) in power electronics, are inscribed in this context.The materials chosen to perform the magnetic functions of those components in their work conditions are the NixZn1-xFe2O4 (0<x<1) ferrites. Copper is added to reduce the firing temperature, from more than 1200 °C to less than 950 °C, allowing cofiring with a conducting metal, and cobalt is added to reduce the power core losses of the sintered ferrite. The final formulation then becomes (NixZnyCuz)1-εCoεFe2-δO4 (x+y+z=1). Finally, bismuth oxide Bi2O3 is added as a sintering aid to lower even more the sintering temperature and avoid diffusion problems.After a bibliographic study, the works were oriented along different axes. Firstly, the ferrite formulation was optimized to elaborate samples with targeted electromagnetic and physicochemical properties. This working axis gathers numerous studies on the Ni-Zn-Cu-Co ferrites formulation, among which the main ones are the study of the influence of iron stoichiometry, the Ni-Zn ratio in the formulation and the cobalt adding process and level. These studies have shown that a light and controlled iron deficiency (~Fe1,98) could improve the properties and the performances of these ferrites. The study of the influence of the Ni/Zn ratio allowed the production of very low permeability ferrites, from 40 to 135, with good power performances. Its results were published in the Journal of the Japan Society of Powder and Metallurgy. Throughout this thesis, the elaboration of ceramic samples, the essential basis of every study, was undertaken at the laboratory, as most of the tests and characterizations. These can be microstructural and physicochemical (XRD, SEM, BET, TDA/TGA…), or electromagnetic (magnetization and permeability measurements, power losses…).The final purpose of this work is power integration, and it represents the second main axis. It also gathers many studies, among which the main ones are the study of the influence of the winding on the losses of an inductor-type component and the influence of the air gap, commonly used to reduce the apparent permeability, not without consequences on the power performances. A total losses measurement campaign has also been undertaken in order to bring out behavioral laws on core losses variation according to induction and frequency.All this work and the results on the ferrite material, his power electronic application, and a good control of the elaboration process (multilayer especially), allowed the production of passive micro-components for integration, with targeted properties and very high performances (core losses reduced by 6 to 10 relative to commercial materials).

L’imagerie par résonance magnétique (IRM) est un outil d’investigation majeur donnant accès de manière non invasive à des nombreuses informations quantitatives et fonctionnelles. La qualité des images obtenues (rapport-signal-sur-bruit, RSB) est cependant limitée dans certaines applications nécessitant des résolutions spatiales et/ou temporelles poussées. Afin d’améliorer la sensibilité de détection des équipements d’IRM, diverses orientations peuvent être suivies telles qu’augmenter l’intensité du champ magnétique des imageurs, améliorer les performances des systèmes de détection radiofréquence (RF), ou encore développer des séquences d’acquisition et des techniques de reconstruction d’images plus efficaces. La thématique globale dans laquelle s’inscrit cette thèse concerne le développement des systèmes de détection RF à haute sensibilité pour l’IRM à haut champ chez l’homme. En particulier, des antennes auto-résonantes basées sur le principe des lignes de transmission sont utilisées parce qu’elles peuvent être réalisée sur substrat souple. Cette adaptabilité géométrique du résonateur permet d’ajuster précisément sa forme aux spécificités morphologiques de la zone anatomique observée, et ainsi d’augmenter le RSB. La première visée technologique de ce projet concerne le développement, de la conception jusqu’à la mise en œuvre dans un appareil 7 T corps entier, d’un système de détection RF flexible à haute sensibilité, utilisant des antennes miniatures associées en réseau. L’utilisation d’un réseau d’antennes miniatures permet d’obtenir des images sur un champ de vue élargi tout en conservant la haute sensibilité inhérente à chaque antenne miniature. De plus, la technologie de l’imagerie parallèle devient accessible, ce qui permet d’accélérer l’acquisition des images. De surcroît, un nouveau schéma de résonateur de ligne transmission avec un degré de liberté supplémentaire est introduit, ce qui permet de réaliser de grands résonateurs multi-tours pour l’IRM à haut champ. Cette thèse décrit le développement, la mise en œuvre et l’évaluation des nouveaux systèmes de détection RF au moyen de simulations analytiques et numériques, et des études expérimentales. / Magnetic resonance imaging (MRI), among other imaging techniques, has become a major backbone of modern medical diagnostics. MRI enables the non-invasive combined, identification of anatomical structures, functional and chemical properties, especially in soft tissues. Nonetheless, applications requiring very high spatial and/or temporal resolution are often limited by the available signal-to-noise ratio (SNR) in MR experiments. Since first clinical applications, image quality in MRI has been constantly improved by applying one or several of the following strategies: increasing the static magnetic field strength, improvement of the radiofrequency (RF) detection system, development of specialized acquisition sequences and optimization of image reconstruction techniques. This work is concerned with the development of highly sensitive RF detection systems for biomedical ultra-high field MRI. In particular, auto-resonant RF coils based on transmission line technology are investigated. These resonators may be fabricated on flexible substrate which enables form-fitting of the RF detector to the target anatomy, leading to a significant SNR gain. The main objective of this work is the development of a flexible RF coil array for high-resolution MRI on a human whole-body 7 T MR scanner. With coil arrays, the intrinsically high SNR of small surface coils may be exploited for an extended field of view. Further, parallel imaging techniques are accessible with RF array technology, allowing acceleration of the image acquisition. Secondly, in this PhD project a novel design for transmission line resonators is developed, that brings an additional degree of freedom in geometric design and enables the fabrication of large multi-turn resonators for high field MR applications. This thesis describes the development, successful implementation and evaluation of novel, mechanically flexible RF devices by analytical and 3D electromagnetic simulations, in bench measurements and in MRI experiments.

Nesta pesquisa foram realizados levantamentos geofísicos utilizando os métodos eletromagnético indutivo - EMI (equipamento EM38) e GPR - Ground Penetrating Radar, visando localizar redes de interferências, tais como, tubulações metálicas, cabos elétricos e conduítes de plástico instalados nas linhas 6 e 7 do Sítio Controlado de Geofísica Rasa do IAG/USP. Os dados EMI foram afetados pelo drift instrumental devido à variação de temperatura. A sua correção foi efetiva por meio do uso de uma função quadrática, realçando os alvos mais profundos. A aquisição em distância permitiu detectar alvos metálicos no subsolo com boa precisão e a aquisição em tempo permitiu fazer um mapeamento regional de alvos metálicos no subsolo. Os melhores resultados foram obtidos com a aquisição em distância, com os sensores posicionados a 10 cm de altura, devido às anomalias ficarem mais nítidas, onde a influência da condutividade do background foi reduzida. Os perfis GPR 2D obtidos com a antena de 400 MHz permitiram detectar os alvos até 1 m de profundidade e com a antena de 200 MHz foi possível detectar quase todos os alvos metálicos e não-metálicos instalados nas linhas estudas do SCGR. Para o GPR quase-3D, na forma de depth slices, foram importantes para estimar as dimensões dos alvos e melhorar a visualização dos resultados. Os resultados obtidos com os métodos EMI e GPR são complementares, sendo ambos recomendados no mapeamento de interferências no subsolo, tendo aplicações diretas nas áreas de planejamento urbano e infra-estrutura nos grandes centros urbanos. / This research was conducted geophysical surveys using inductive electromagnetic - IEM (EM38 equipment) and GPR - Ground Penetrating Radar methods, to locate network interference, such as metal pipes, electric cables and plastic conduit installed in lines 6 and 7 of test site of the IAG/USP (SCGR). IEM data were affected by instrumental drift due to temperature variation. The correction was effective through the use of a quadratic function, highlighting the deeper targets. The acquisition targets identified in the distance underground metal with good accuracy and acquisition time allowed to make a survey of regional targets metal underground. The best results were obtained with the acquisition in distance with the sensors placed at 10 cm in height, due to deficiencies become more clear, where the influence of the background conductivity was reduced. The 2D GPR profiles obtained with the antenna of 400 MHz to detect the target by 1 m depth and the antenna of 200 MHz was possible to detect almost all metal targets and non-metallic lines installed in the study SCGR. GPR to the quasi-3D in the form of depth slices, were important for estimating the size of the targets and improve the visualization of results. The results obtained with the IEM and GPR methods are complementary, and both are recommended in mapping interference underground, with direct applications in the areas of urban planning and infrastructure in urban centers.

Nesta pesquisa foram realizados levantamentos geofísicos utilizando os métodos eletromagnético indutivo - EMI (equipamento EM38) e GPR - Ground Penetrating Radar, visando localizar redes de interferências, tais como, tubulações metálicas, cabos elétricos e conduítes de plástico instalados nas linhas 6 e 7 do Sítio Controlado de Geofísica Rasa do IAG/USP. Os dados EMI foram afetados pelo drift instrumental devido à variação de temperatura. A sua correção foi efetiva por meio do uso de uma função quadrática, realçando os alvos mais profundos. A aquisição em distância permitiu detectar alvos metálicos no subsolo com boa precisão e a aquisição em tempo permitiu fazer um mapeamento regional de alvos metálicos no subsolo. Os melhores resultados foram obtidos com a aquisição em distância, com os sensores posicionados a 10 cm de altura, devido às anomalias ficarem mais nítidas, onde a influência da condutividade do background foi reduzida. Os perfis GPR 2D obtidos com a antena de 400 MHz permitiram detectar os alvos até 1 m de profundidade e com a antena de 200 MHz foi possível detectar quase todos os alvos metálicos e não-metálicos instalados nas linhas estudas do SCGR. Para o GPR quase-3D, na forma de depth slices, foram importantes para estimar as dimensões dos alvos e melhorar a visualização dos resultados. Os resultados obtidos com os métodos EMI e GPR são complementares, sendo ambos recomendados no mapeamento de interferências no subsolo, tendo aplicações diretas nas áreas de planejamento urbano e infra-estrutura nos grandes centros urbanos. / This research was conducted geophysical surveys using inductive electromagnetic - IEM (EM38 equipment) and GPR - Ground Penetrating Radar methods, to locate network interference, such as metal pipes, electric cables and plastic conduit installed in lines 6 and 7 of test site of the IAG/USP (SCGR). IEM data were affected by instrumental drift due to temperature variation. The correction was effective through the use of a quadratic function, highlighting the deeper targets. The acquisition targets identified in the distance underground metal with good accuracy and acquisition time allowed to make a survey of regional targets metal underground. The best results were obtained with the acquisition in distance with the sensors placed at 10 cm in height, due to deficiencies become more clear, where the influence of the background conductivity was reduced. The 2D GPR profiles obtained with the antenna of 400 MHz to detect the target by 1 m depth and the antenna of 200 MHz was possible to detect almost all metal targets and non-metallic lines installed in the study SCGR. GPR to the quasi-3D in the form of depth slices, were important for estimating the size of the targets and improve the visualization of results. The results obtained with the IEM and GPR methods are complementary, and both are recommended in mapping interference underground, with direct applications in the areas of urban planning and infrastructure in urban centers.

Actuellement, les systèmes permettant de transférer de l’énergie dans le but de recharger les accumulateurs d’appareils électroniques sans l’emploi de câble se démocratisent davantage chaque jour. On comprend donc bien l’intérêt de tels systèmes dans des environnements embarqués et confinés tels que l’habitacle d’un véhicule. Le principe de l’induction magnétique réside dans un transfert de flux magnétique entre deux antennes inductives. Le champ magnétique servira de vecteur au transport d’une puissance électrique, puisque c’est au travers de cette création de flux magnétique que sera échangée ou transférée la puissance d’un émetteur vers un récepteur. Un tel système d’émission-réception de puissance utilisant le principe d’induction magnétique contient un émetteur, des antennes (bobines) inductives couplées et un récepteur. Un premier chapitre sera donc consacré à l’étude des antennes d’un point de vue théorique et technologique. Des modèles électromagnétiques d’antennes inductives seront développés, et après validation par corrélation avec des mesures électriques et électromagnétiques, ils seront employés au travers d’intenses simulations électromagnétiques. Ceci afin de montrer l’impact des paramètres définissant ces antennes inductives sur leurs comportements électrique et électromagnétique. Une fois les antennes inductives optimisées et leurs paramètres clés identifiés, on étudiera dans un deuxième temps les effets de l’induction magnétique lorsque qu’une antenne d’émission et une autre de réception sont présentées ensembles et mises en condition de transfert d’énergie. On mettra donc en évidence le principe de couplage magnétique entre les antennes ainsi que la notion de rendement de puissance appelé aussi efficacité de liaison. Les différents paramètres des antennes seront là aussi caractérisés afin d‘étudier leur influence sur le transfert d’énergie inductif. Le tout illustré de la même manière que précédemment, en s’appuyant sur d’intenses simulations électromagnétiques et des modèles validés par rapport à différentes méthodes de mesure. Ceci dans le but de comprendre les mécanismes de fonctionnement et d’optimisation d’un système de transfert d’énergie par induction magnétique ainsi que de proposer des règles générales de conception d’antennes inductives. Dans un troisième temps, on présentera les différents étages électroniques composant les systèmes de transfert d’énergie inductif. Une partie sera dédiée à la définition du point de vue système des éléments constituant la chaine complète d’émission et de réception. La conception, l’optimisation et la mesure des amplificateurs de puissance utilisés au niveau de l’émetteur seront également présentés. En effet, ces systèmes doivent être suffisamment performants afin de transférer des puissances capables d’alimenter des appareils électroniques de type téléphones tout en ayant un bilan de puissance efficace avec des pertes limitées. A partir de modèles de circuits émetteur et récepteur et en s’appuyant sur des simulations circuits, nous estimerons les bilans de puissances afin d’évaluer les performances et les limites des différents systèmes. Ces simulations une fois validées par mesures permettront de quantifier l’efficacité du transfert de puissance et proposer des voies d’optimisation. Ces systèmes et technologies sont de plus en plus utilisés pour l’électronique grand public et il existe actuellement plusieurs standards régissant le transfert d’énergie inductif. Les différentes études présentées dans cette thèse seront donc orientées vers ces différentes normes, et des analogies seront réalisées tout le long du mémoire afin de mettre en exergue leurs différents principes de fonctionnement. / Nowadays there is a strong demand of systems allowing to transfer energy in a wirelessly way to small electronic devices. So we can well understand the interest of such systems in embedded environments such as vehicle cockpit. The principle of magnetic induction comes from a magnetic flux exchange between two inductive antennas. The magnetic field will be used to transport an electrical power from an emitter to a receiver. These systems using the magnetic induction to transfer energy contain an emitter, inductive antennas (coils) and a receiver. A first chapter will be dedicated to the antennas employed in inductive wireless power transfer systems on theoretical and technological points of views. An electromagnetic modeling of these inductive antennas will be realized and validated through correlation with measurements. Once the modeling process defined and the validations done, it will be used through intensive electromagnetic simulations in order to show the impact of antennas parameters on their electrical and electromagnetic performances. After the inductive antennas characterization and their key parameters identification done, we will study in a second time the magnetic induction effects when emission and reception antennas are placed together in order to realize an inductive power transfer. Notions of magnetic coupling which appears between inductive antennas and magnetic efficiency which characterizes how much quantities of power are transferred will be highlighted. In the same conditions as before, the impact of antennas parameters on the power transfer and magnetic coupling will be investigated through electromagnetic modeling of inductive antennas and the use of intensive electromagnetic simulations. Thus, we will have the opportunity to precisely understand the meaning of the inductive power transfer and the different ways of optimizations. By this way, we will also propose some general design guidelines for antennas employed in inductive wireless power transfer systems. A third chapter will be dedicated to the presentation of the different electronic stages used in inductive wireless power transfer systems. A part of it will be employed on the definitions of the different elements allowing the wireless power transfer on a system approach. The design, optimization and measurement of power amplifiers used on the emission stage will be presented too.. Indeed, it is necessary to have efficient power amplification in order to transfer the required power to different receivers such as phones at the same time to limit the power losses. From circuit modeling of different emitter and receiver and with circuit simulations, we will develop power budgets in order to evaluate the performances and limits of these systems. Once the simulation validated by measurement, we will be able to quantify the total power transfer efficiency and propose optimization ways. Because of the current existence of different inductive wireless power standards on the industrial market for electronic consumer, analogies with them will be done all along the different steps of this thesis in order to highlighted their different functioning principles.

La détection d'homologues lointains est essentielle pour le classement fonctionnel et structural des séquences protéiques et pour l'amélioration de l'annotation des génomes très divergents. Pour le classement des séquences, nous présentons la méthode "ILP-SVM homology", combinant la programmation logique inductive (PLI) et les modèles propositionnels. Elle propose une nouvelle représentation logique des propriétés physico-chimiques des résidus et des positions conservées au sein de l'alignement de séquences. Ainsi, PLI trouve les règles les plus fréquentes et les utilise pour la phase d'apprentissage utilisant des modèles d'arbre de décision ou de machine à vecteurs de support. La méthode présente au moins les mêmes performances que les autres méthodes trouvées dans la littérature. Puis, nous proposons la méthode CASH pour annoter les génomes très divergents. CASH a été appliqué à Plasmodium falciparum, mais reste applicable à toutes les espèces. CASH utilise aussi bien l'information issue de génomes proches ou éloignés de P. falciparum. Chaque domaine connu est ainsi représenté par un ensemble de modèles évolutifs, et les sorties sont combinées par un méta-classificateur qui assigne un score de confiance à chaque prédiction. Basé sur ce score et sur des propriétés de co-ocurrences de domaines, CASH trouve l'architecture la plus probable de chaque séquence en appliquant une approche d'optimisation multi-objectif. CASH est capable d'annoter 70% des domaines protéiques de P. falciparum, contre une moyenne de 58% pour ses concurrents. De nouveaux domaines protéiques ont pu être caractérisés au sein de protéines de fonction inconnue ou déjà annotées.

This research investigates how to draw energy from a distant emanating and alternating (i.e., AC) magnetic source and deliver it to a battery (i.e., DC). The objective is to develop, design, simulate, build, test, and evaluate a CMOS charger integrated circuit (IC) that wirelessly charges the battery of a microsystem. A fundamental challenge here is that a tiny receiver coil only produces mV's of AC voltage, which is difficult to convert into DC form. Although LC-boosted diode-bridge rectifiers in the literature today extract energy from similar AC sources, they can do so only when AC voltages are higher than what miniaturized coils can produce, unless tuned off-chip capacitors are available, which counters the aim of integration. Therefore, rather than rectify the AC voltage, this research proposes to rectify the current that the AC voltage induces in the coil. This way, the system can still draw power from voltages that fall below the inherent threshold limit of diode-bridge rectifiers. Still, output power is low because, with these low currents, small coils can only extract a diminutive fraction of the magnetic energy available, which is why investing battery energy is also part of this research. Ultimately, the significance of increasing the power that miniaturized platforms can output is higher integration and functionality of micro-devices, like wireless microsensors and biomedical implants.

The Wonderfonteinspruit (WFS) flows through the richest gold mining region in the world and has subsequently been exposed to the related pollution for more than a century. In order to determine the extent of mining related pollution in the WFS, sediment, water, soil, grass and cattle tissue samples were collected, analysed and compared from an experimental group and a control group. This study identified cobalt, nickel, zinc, selenium, cadmium, gold, lead and uranium as elements of interest by comparing sediment samples from the WFS and the Mooi River (MR) (which served as a control or background site). The cobalt concentration was found to be 16.37 times higher, the nickel concentration was 30.4 times higher, the copper concentration was 3.59 times higher, the zinc concentration was 103.49 times higher, the selenium concentration was 7.14 times higher, the cadmium concentration was 17.88 times higher, the gold concentration was 4.78 times higher, the lead concentration was 1.32 times higher and the uranium concentration was 375.78 times higher in the initial comparison with sediments from the MR. These results were all found to be significant. All these elements are by products of non-ferrous mining activities as was described in the literature review. The elevated concentrations of these elements, which were found in the streambed sediment of a site in the Lower-Wonderfonteinspruit, suggest that they could have resulted due to upstream gold mining activities. These gold mining activities were initiated more than a century ago and continue to this day. Analysis of the different particle size fractions (sand, silt and clay fractions) revealed that the highest elemental concentrations were found in the clay sized fractions. The clay sized fraction usually contains secondary soil minerals which have the ability to adsorb dissolved cations onto their surface areas. Further analysis revealed that the sand fraction of the WFS sediment contained a substantial concentration of cobalt, nickel, copper, zinc, lead and uranium which, upon initial inspection could not be explained. X-Ray Diffraction (XRD) analysis revealed that more than 90 % of the WFS sand, silt and clay fractions consisted of quartz, which was much higher than that of the MR. Due to the particle size of quartz, it generally dominates the sand and silt fractions, and finding it at levels above 90 % in the clay sized fraction is thought to be highly irregular. This could be explained by the extraction and processing of gold reefs from the goldfields in the catchment. The gold reefs consisted of quartz veins that were milled to a fine dust and pumped onto slime and sand dumps after the gold was extracted. The most abundant ore minerals found within these dumps were uraninite(UO2), brannerite (UO3Ti2O4), arsenopyrite (FeAsS), cobaltite (CoAsS), galena (PbS), pyrrhotite (FeS), gersdofite (NiAsS) and chromite (FeCr2O4), which contain some of the elements of interest. These dumps are either located in close proximity to the WFS or connected to the WFs via canals or pipelines. Erosion of these dumps would then introduce this finely milled quartz into the stream system. Therefore, the elements found in the sediment of the WFS were not only introduced to the system in the dissolved form, but also in the particulate form. The water samples that were collected from the experimental site (WFS) were found to exceed the cobalt, nickel, copper, zinc, selenium and cadmium concentrations ranges which are normally found in natural waters. In addition to this, the cadmium, lead and nickel concentration in the WFS water samples were found to occasionally exceed the target water quality ranges for livestock water as set by DWAF (1996). Water samples that were collected from the control group were found to exceed only the selenium concentration found in natural water sources as found by Crittenden et al., (2005). Cattle in the experimental group drink directly from the WFS and may stir up the sediment and thereby increasing the elemental concentrations within the water prior to ingestion. The target water quality ranges (TWQR) for livestock watering, as set by DWAF 1996, were exceeded by the average nickel and lead concentrations found in the disturbed WFS water samples. Although the elemental concentrations in the respective water samples were fairly low there was a definite practical significant difference between the WFS water and the MR water samples, as well as the disturbed WFS water and the MR water samples. The WFS water quality seemed to have a very large standard deviation which could serve as an indication that the elemental concentrations are highly variable over time. The elemental concentrations that were found in soil samples from the respective sites were compared to elemental concentrations found in normal agricultural soil as presented by Bergman (1992), which revealed the following results. The cobalt concentrations in the soil samples from the soil along WFS site, soil along MR site and irrigation MR site exceeded the agricultural threshold value. The nickel concentrations in the soil samples from the soil along WFS site, soil along MR site, wetland WFS and irrigation MR site exceeded the agricultural threshold value. The zinc concentrations in the soil samples from the soil along WFS site exceeded the agricultural threshold value. Copper, selenium, cadmium and lead concentrations did not exceed the agricultural threshold values in any of the respective sites. The agricultural threshold value for uranium concentrations was exceeded in the soil samples from the soil along the WFS site and the wetland WFS site. The comparison between the elemental concentrations that were found in the soil samples from the irrigated soil WFS site and the irrigated soil MR site revealed a practically significant difference for the copper, zinc and uranium concentrations. The comparison between the elemental concentrations found in soil samples from the soil along the WFS site and the soil along the MR site revealed a practically significant difference for all elements of interest. The analysis of the elemental concentration in the different particle size fractions of soil samples from all the sites (excluding the irrigated pastures) displayed highest elemental concentrations in the clay sized fraction. The elemental concentrations that were found in this fraction are generally considered to be available for plant uptake, as most of them are usually bound to the surface of secondary soil minerals. The sites with the highest concentration of plant available elements were found to be the soil along WFS site and the wetland WFS site. The elemental concentrations found in the grass samples from the respective sampling sites were compared to elemental concentrations that are normally found in grass pastures (Underwood & Suttle, 2001). The cobalt, nickel, copper and concentrations that were found in the grass samples from most of the sites in both the control and experimental groups were all found to exceed the concentration ranges found in natural pastures. The cadmium and zinc concentrations in the grass samples from the soil along WFS site were found to exceed the respective concentration ranges found in natural pastures. The normal uranium concentration found in irrigated or natural grasses could not be found in an extensive search. Dreesen et al. (1982) reported 0.16 mg/kg uranium in grasses and 1.8 mg/kg uranium in shrubs that grew on soil-covered tailings material. All the sites in the experimental group, including the control WFS site, drastically exceeded these concentrations, which may suggest that the grasses in the experimental sites have been exposed to elevated uranium concentrations. The grass samples with the highest average elemental concentrations were found in the soil along WFS site and irrigated soil WFS site. Lead was to be the only element of interest to have the highest concentration in grass samples from the irrigated soil WFS site. The irrigated soil WFS site portrayed significant transfer factors for nickel, copper, zinc, lead and uranium. This could serve as an indication that the grasses under irrigation in the WFS site absorb and accumulate the highest concentration of elements in respect to the soil concentrations found in the various sites. Therefore, the irrigation from the WFS has a profound effect on the nickel, copper, zinc, lead and uranium concentration in the grass samples under irrigation. The results obtained from the comparative analysis of the elemental concentration in grass samples from the irrigation WFS and irrigation MR sites revealed that all elemental concentrations except for that of zinc had a difference that was practically significant, with the uranium concentration having the largest effect size. The results obtained from the comparative analysis of the elemental concentration in grass samples from the soil along WFS and soil along MR sites revealed that all elemental concentrations had a difference that was practically significant uranium, nickel and zinc concentrations having the largest effect sizes. Considering that a large effect size is achieved at a value equal to or greater than 0.8, the uranium concentration therefore had a massive difference in both comparisons. The results obtained from the comparative analysis of the elemental concentration in grass samples from the wetland WFS and control WFS sites revealed that only the cobalt, nickel and uranium concentrations had differences that were practically significant, with the cobalt concentration having the largest effect size. The results obtained from the comparative analysis of the elemental concentration in the grass samples from the soil along WFS and control WFS sites revealed that all the elemental concentrations except for the lead concentration had a difference that was practically significant. The cobalt, nickel and zinc had the largest effect sizes. The elemental concentrations that were found in cattle liver, kidney and muscle tissue samples from both the experimental and control groups were compared to elemental concentrations normally found in cattle samples as found in Pulse (1994), ATSDR (2004), and ATSDR (2011). This comparison revealed the following results: The nickel, cadmium and lead concentration that were found in the cattle liver, kidney and muscle tissue samples from both the experimental and control groups were found to be within the ranges normally found in cattle. Cobalt concentrations found in the liver and muscle tissue samples of cattle from both the experimental and control groups exceeded the normal ranges, and the cobalt concentrations found in the kidney samples from the experimental group exceeded the normal range. The copper concentration found in the kidney samples from the cattle in the experimental group exceeded that of the normal concentration range. The zinc concentration found in the liver and kidney samples in the cattle from the experimental group, and the kidney samples from the cattle in the control group exceeded the normal range. The selenium concentration found in the liver, kidney and muscle tissue samples in the cattle from the experimental group, and the kidney samples from the cattle in the control group exceeded the normal range. The uranium concentration found in the liver, kidney and muscle tissue samples in the cattle from the experimental group exceeded the normal range. The comparison between cattle tissue samples from the experimental and control group revealed that nickel, zinc, selenium, lead and uranium concentrations all reveal a practically significant difference. Uranium, nickel and lead portrayed the largest differences between the two groups. The uranium concentration in the cattle samples from the experimental group was 126.75 times higher in the liver, 4350 times higher in the kidney, 47.75 times higher in the spleen, 31.6 times higher in the muscle tissue, 60 times higher in the bone and 129 times higher in the hair than that of the cattle samples from the control group. In addition to this, the uranium did not only accumulate in the predicted tissue samples (bone, liver and kidney), but also in the muscle tissue samples. The nickel concentrations in the cattle samples were all found to be higher in the experimental group, with liver 1.4 times higher, kidney 387.5 times higher, spleen 2.1 times higher, muscle tissue 2.8 times higher, bone 167.5 times higher and hair 76.5 times higher than that of the cattle samples from the control group. The lead concentrations found in the cattle samples from the experimental group were found to be 3.8 times higher in the liver, 17.3 times higher in the kidney, 3.3 times higher in the spleen, 3.2 times higher in the muscle tissue, 9 times higher in the bone and 12.2 times higher in the hair than the cattle samples from the control group. Furthermore, the study revealed that the major route of ingestion for all the elements of interest, excluding nickel and cobalt was via the ingestion of grass. The major route for nickel and cobalt ingestion was via soil ingestion. The elemental concentrations from water ingestion were found to be a less significant. It was shown that a predictive cattle consumption model was developed and calibrated from data gathered from a control and experimental group. Animal matter analysed for both groups were related to the cattle age of six years. Although good correlation between observed and simulated values was achieved, the exiting model fit is non-unique. To obtain a more precise model fit a similar dataset is required for both groups, but at a different age. The predictive model also showed that if only grass were to be used as input, there were no significant changes in the correlation between observed and simulated values. This has a huge advantage in terms of costs associated with laboratory analyses as the analysis of grass will be sufficient for using the model. A human health risk assessment was performed based on the results of the cattle consumption model. It was shown that no toxic risk exits for both the control and experimental groups if an intake rate of 0.13 kg of meat per day was assumed. Furthermore, Figure 6-11 clearly indicates that an intake rate of up to 0.38 kg of meat per day also has no toxic risk for both groups, which strongly suggests that there is no risk to the human food chain. The cattle grazing in the WFS appear to be in a good physical condition and according to the farmer; the reproduction rate is at desirable levels. Good farming practices would have also played a significant role to achieve this. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.

The Wonderfonteinspruit (WFS) flows through the richest gold mining region in the world and has subsequently been exposed to the related pollution for more than a century. In order to determine the extent of mining related pollution in the WFS, sediment, water, soil, grass and cattle tissue samples were collected, analysed and compared from an experimental group and a control group. This study identified cobalt, nickel, zinc, selenium, cadmium, gold, lead and uranium as elements of interest by comparing sediment samples from the WFS and the Mooi River (MR) (which served as a control or background site). The cobalt concentration was found to be 16.37 times higher, the nickel concentration was 30.4 times higher, the copper concentration was 3.59 times higher, the zinc concentration was 103.49 times higher, the selenium concentration was 7.14 times higher, the cadmium concentration was 17.88 times higher, the gold concentration was 4.78 times higher, the lead concentration was 1.32 times higher and the uranium concentration was 375.78 times higher in the initial comparison with sediments from the MR. These results were all found to be significant. All these elements are by products of non-ferrous mining activities as was described in the literature review. The elevated concentrations of these elements, which were found in the streambed sediment of a site in the Lower-Wonderfonteinspruit, suggest that they could have resulted due to upstream gold mining activities. These gold mining activities were initiated more than a century ago and continue to this day. Analysis of the different particle size fractions (sand, silt and clay fractions) revealed that the highest elemental concentrations were found in the clay sized fractions. The clay sized fraction usually contains secondary soil minerals which have the ability to adsorb dissolved cations onto their surface areas. Further analysis revealed that the sand fraction of the WFS sediment contained a substantial concentration of cobalt, nickel, copper, zinc, lead and uranium which, upon initial inspection could not be explained. X-Ray Diffraction (XRD) analysis revealed that more than 90 % of the WFS sand, silt and clay fractions consisted of quartz, which was much higher than that of the MR. Due to the particle size of quartz, it generally dominates the sand and silt fractions, and finding it at levels above 90 % in the clay sized fraction is thought to be highly irregular. This could be explained by the extraction and processing of gold reefs from the goldfields in the catchment. The gold reefs consisted of quartz veins that were milled to a fine dust and pumped onto slime and sand dumps after the gold was extracted. The most abundant ore minerals found within these dumps were uraninite(UO2), brannerite (UO3Ti2O4), arsenopyrite (FeAsS), cobaltite (CoAsS), galena (PbS), pyrrhotite (FeS), gersdofite (NiAsS) and chromite (FeCr2O4), which contain some of the elements of interest. These dumps are either located in close proximity to the WFS or connected to the WFs via canals or pipelines. Erosion of these dumps would then introduce this finely milled quartz into the stream system. Therefore, the elements found in the sediment of the WFS were not only introduced to the system in the dissolved form, but also in the particulate form. The water samples that were collected from the experimental site (WFS) were found to exceed the cobalt, nickel, copper, zinc, selenium and cadmium concentrations ranges which are normally found in natural waters. In addition to this, the cadmium, lead and nickel concentration in the WFS water samples were found to occasionally exceed the target water quality ranges for livestock water as set by DWAF (1996). Water samples that were collected from the control group were found to exceed only the selenium concentration found in natural water sources as found by Crittenden et al., (2005). Cattle in the experimental group drink directly from the WFS and may stir up the sediment and thereby increasing the elemental concentrations within the water prior to ingestion. The target water quality ranges (TWQR) for livestock watering, as set by DWAF 1996, were exceeded by the average nickel and lead concentrations found in the disturbed WFS water samples. Although the elemental concentrations in the respective water samples were fairly low there was a definite practical significant difference between the WFS water and the MR water samples, as well as the disturbed WFS water and the MR water samples. The WFS water quality seemed to have a very large standard deviation which could serve as an indication that the elemental concentrations are highly variable over time. The elemental concentrations that were found in soil samples from the respective sites were compared to elemental concentrations found in normal agricultural soil as presented by Bergman (1992), which revealed the following results. The cobalt concentrations in the soil samples from the soil along WFS site, soil along MR site and irrigation MR site exceeded the agricultural threshold value. The nickel concentrations in the soil samples from the soil along WFS site, soil along MR site, wetland WFS and irrigation MR site exceeded the agricultural threshold value. The zinc concentrations in the soil samples from the soil along WFS site exceeded the agricultural threshold value. Copper, selenium, cadmium and lead concentrations did not exceed the agricultural threshold values in any of the respective sites. The agricultural threshold value for uranium concentrations was exceeded in the soil samples from the soil along the WFS site and the wetland WFS site. The comparison between the elemental concentrations that were found in the soil samples from the irrigated soil WFS site and the irrigated soil MR site revealed a practically significant difference for the copper, zinc and uranium concentrations. The comparison between the elemental concentrations found in soil samples from the soil along the WFS site and the soil along the MR site revealed a practically significant difference for all elements of interest. The analysis of the elemental concentration in the different particle size fractions of soil samples from all the sites (excluding the irrigated pastures) displayed highest elemental concentrations in the clay sized fraction. The elemental concentrations that were found in this fraction are generally considered to be available for plant uptake, as most of them are usually bound to the surface of secondary soil minerals. The sites with the highest concentration of plant available elements were found to be the soil along WFS site and the wetland WFS site. The elemental concentrations found in the grass samples from the respective sampling sites were compared to elemental concentrations that are normally found in grass pastures (Underwood & Suttle, 2001). The cobalt, nickel, copper and concentrations that were found in the grass samples from most of the sites in both the control and experimental groups were all found to exceed the concentration ranges found in natural pastures. The cadmium and zinc concentrations in the grass samples from the soil along WFS site were found to exceed the respective concentration ranges found in natural pastures. The normal uranium concentration found in irrigated or natural grasses could not be found in an extensive search. Dreesen et al. (1982) reported 0.16 mg/kg uranium in grasses and 1.8 mg/kg uranium in shrubs that grew on soil-covered tailings material. All the sites in the experimental group, including the control WFS site, drastically exceeded these concentrations, which may suggest that the grasses in the experimental sites have been exposed to elevated uranium concentrations. The grass samples with the highest average elemental concentrations were found in the soil along WFS site and irrigated soil WFS site. Lead was to be the only element of interest to have the highest concentration in grass samples from the irrigated soil WFS site. The irrigated soil WFS site portrayed significant transfer factors for nickel, copper, zinc, lead and uranium. This could serve as an indication that the grasses under irrigation in the WFS site absorb and accumulate the highest concentration of elements in respect to the soil concentrations found in the various sites. Therefore, the irrigation from the WFS has a profound effect on the nickel, copper, zinc, lead and uranium concentration in the grass samples under irrigation. The results obtained from the comparative analysis of the elemental concentration in grass samples from the irrigation WFS and irrigation MR sites revealed that all elemental concentrations except for that of zinc had a difference that was practically significant, with the uranium concentration having the largest effect size. The results obtained from the comparative analysis of the elemental concentration in grass samples from the soil along WFS and soil along MR sites revealed that all elemental concentrations had a difference that was practically significant uranium, nickel and zinc concentrations having the largest effect sizes. Considering that a large effect size is achieved at a value equal to or greater than 0.8, the uranium concentration therefore had a massive difference in both comparisons. The results obtained from the comparative analysis of the elemental concentration in grass samples from the wetland WFS and control WFS sites revealed that only the cobalt, nickel and uranium concentrations had differences that were practically significant, with the cobalt concentration having the largest effect size. The results obtained from the comparative analysis of the elemental concentration in the grass samples from the soil along WFS and control WFS sites revealed that all the elemental concentrations except for the lead concentration had a difference that was practically significant. The cobalt, nickel and zinc had the largest effect sizes. The elemental concentrations that were found in cattle liver, kidney and muscle tissue samples from both the experimental and control groups were compared to elemental concentrations normally found in cattle samples as found in Pulse (1994), ATSDR (2004), and ATSDR (2011). This comparison revealed the following results: The nickel, cadmium and lead concentration that were found in the cattle liver, kidney and muscle tissue samples from both the experimental and control groups were found to be within the ranges normally found in cattle. Cobalt concentrations found in the liver and muscle tissue samples of cattle from both the experimental and control groups exceeded the normal ranges, and the cobalt concentrations found in the kidney samples from the experimental group exceeded the normal range. The copper concentration found in the kidney samples from the cattle in the experimental group exceeded that of the normal concentration range. The zinc concentration found in the liver and kidney samples in the cattle from the experimental group, and the kidney samples from the cattle in the control group exceeded the normal range. The selenium concentration found in the liver, kidney and muscle tissue samples in the cattle from the experimental group, and the kidney samples from the cattle in the control group exceeded the normal range. The uranium concentration found in the liver, kidney and muscle tissue samples in the cattle from the experimental group exceeded the normal range. The comparison between cattle tissue samples from the experimental and control group revealed that nickel, zinc, selenium, lead and uranium concentrations all reveal a practically significant difference. Uranium, nickel and lead portrayed the largest differences between the two groups. The uranium concentration in the cattle samples from the experimental group was 126.75 times higher in the liver, 4350 times higher in the kidney, 47.75 times higher in the spleen, 31.6 times higher in the muscle tissue, 60 times higher in the bone and 129 times higher in the hair than that of the cattle samples from the control group. In addition to this, the uranium did not only accumulate in the predicted tissue samples (bone, liver and kidney), but also in the muscle tissue samples. The nickel concentrations in the cattle samples were all found to be higher in the experimental group, with liver 1.4 times higher, kidney 387.5 times higher, spleen 2.1 times higher, muscle tissue 2.8 times higher, bone 167.5 times higher and hair 76.5 times higher than that of the cattle samples from the control group. The lead concentrations found in the cattle samples from the experimental group were found to be 3.8 times higher in the liver, 17.3 times higher in the kidney, 3.3 times higher in the spleen, 3.2 times higher in the muscle tissue, 9 times higher in the bone and 12.2 times higher in the hair than the cattle samples from the control group. Furthermore, the study revealed that the major route of ingestion for all the elements of interest, excluding nickel and cobalt was via the ingestion of grass. The major route for nickel and cobalt ingestion was via soil ingestion. The elemental concentrations from water ingestion were found to be a less significant. It was shown that a predictive cattle consumption model was developed and calibrated from data gathered from a control and experimental group. Animal matter analysed for both groups were related to the cattle age of six years. Although good correlation between observed and simulated values was achieved, the exiting model fit is non-unique. To obtain a more precise model fit a similar dataset is required for both groups, but at a different age. The predictive model also showed that if only grass were to be used as input, there were no significant changes in the correlation between observed and simulated values. This has a huge advantage in terms of costs associated with laboratory analyses as the analysis of grass will be sufficient for using the model. A human health risk assessment was performed based on the results of the cattle consumption model. It was shown that no toxic risk exits for both the control and experimental groups if an intake rate of 0.13 kg of meat per day was assumed. Furthermore, Figure 6-11 clearly indicates that an intake rate of up to 0.38 kg of meat per day also has no toxic risk for both groups, which strongly suggests that there is no risk to the human food chain. The cattle grazing in the WFS appear to be in a good physical condition and according to the farmer; the reproduction rate is at desirable levels. Good farming practices would have also played a significant role to achieve this. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.