Pour respecter les droits d'auteur, la version électronique de ce mémoire a été dépouillée de certains documents visuels. La version intégrale du mémoire a été déposée à la Division de la gestion des documents et des archives. / Le Staffordshire Hoard est un trésor anglo-saxon qui date des 6e et 7e siècles qui fut découvert en juillet 2009 par un détectoriste dans un champ du comté du Staffordshire en Angleterre. Ce trésor est composé d’environ 4600 fragments d’artéfacts représentant pour la plupart des garnitures d’épées en or et en argent. Bien que nous retrouvions aussi dans le Hoard certains objets ecclésiastiques, comme une grande croix en or ainsi qu’une bande inscrite en latin, aucune pièce de monnaie ne fut retrouvée, ni aucune lame d’épée. Le Staffordshire Hoard pose beaucoup de questions, notamment par sa composition inédite et aussi en raison du mauvais état dans lequel les objets furent retrouvés. Depuis sa découverte en 2009, les chercheurs se sont majoritairement posé les mêmes questions, à savoir de quel type de Hoard il s’agit, à qui il appartient et pourquoi il fut enterré. Avec ce mémoire, nous allons plutôt emprunter un autre chemin. En effet, nous étudierons plutôt les aspects matériels et techniques de la construction des artéfacts en or décorés avec la technique du cloisonné, et particulièrement le seax set. Ceci nous permettra dans un premier temps de comprendre comment ce type d’objet fut fabriqué par une société en particulier à l’époque du haut Moyen-Âge. Dans un second temps, l’étude de ces sujets aidera à répondre à une question qui fut souvent mise de côté par les différents chercheurs s’étant intéressés au Staffordshire Hoard, à savoir pourquoi aucune lame d’épée ne fut retrouvée dans cet assemblage. / The Staffordshire Hoard is an Anglo-Saxon treasure dating from the 6th and 7th centuries that was discovered in July 2009 by a detectorist in a field in the county of Staffordshire, England. This treasure is composed of approximately 4600 fragments of artefacts representing mostly gold and silver sword fittings. Although some ecclesiastical items were also found in the Hoard, such as a gold Great Cross and a Latin inscribed strip, neither coins nor sword blades were found. The Staffordshire Hoard raises many questions, due to its unusual composition and the poor condition in which the objects were found. Since its discovery in 2009, researchers have mostly asked the same questions, namely what type of hoard it is, to whom it belongs and why it was buried. With this dissertation, we will take a different path. Instead, we will study the material and technical aspects of the construction of gold artefacts decorated with the cloisonné technique, specifically the seax set. This will allow us in first place to understand how this type of object was made by a particular society in the early Middle Ages. Secondly, the study of these objects will help us to answer a question that has often been put aside by various researchers interested in the Staffordshire Hoard, namely why no sword blades were found in this assemblage.

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No description available.

This study contributes to the understanding of major river evolution in Southeast Asia during the Cenozoic. In order to trace the evolution of a hypothesized palaeo-Yarlung Tsangpo-Irrawaddy River, this work undertakes the first systematic provenance study of detrital minerals from Cenozoic synorogenic fluvial and deltaic sedimentary rocks of the Central Burma Basin, employing a combination of high precision geochronology, thermochronology, and geochemistry analytical techniques on single grain detrital zircon and white mica. The dataset is compared to published isotopic data from potential source terranes in order to determine source provenance and exhumation history from source to sink. A Yarlung Tsangpo-Irrawaddy connection existed as far back as ca. 42 Ma and disconnection occurred at 18–20 Ma, based on provenance changes detected using a combination of U-Pb ages and εHf(t) values on detrital zircons, and ⁴ºAr/³⁹Ar dating on detrital micas. During the Eocene and Oligocene, units are dominated by U-Pb age and high positive εHf(t) values, characteristic of a southern Lhasa Gangdese magmatic arc source. An antecedent Yarlung Tsangpo-Irrawaddy River system formed the major river draining the eastern Himalaya at this time. A significant change in provenance is seen in the early Miocene, where detritus is predominantly derived from bedrock of the eastern Himalayan syntaxis, western Yunnan and Burma, a region drained by the modern Irrawaddy-Chindwin river system characterized by Cenozoic U-Pb ages and negative εHf(t) values. This is attributed to the disconnection of the Yarlung-Irrawaddy River and capture by the proto-Brahmaputra River, re-routing Tibetan Transhimalayan detritus to the eastern Himalayan foreland basin. Re-set zircon fission track ages of 14-8 Ma present in all units is used to infer post-depositional basin evolution related to changes in the stress regime accommodating the continued northward migration of India. The early Miocene initiation of the Jiali-Parlung-Gaoligong-Sagaing dextral shear zone and the continued northward movement of the coupled India-Burma plate aided in focusing deformation inside the syntaxis contributing to the disconnection of the Yarlung Tsangpo-Irrawaddy system, linking surface deformation and denudation with processes occurring at deeper crustal levels.

Garnet-bearing gneisses from the vicinity of Passo del Sole, Central Swiss Alps, have undergone a complex history of metamorphism and deformation that has imbued them with unique compositional and textural variations. Complex, concentric zoning patterns in garnet may be correlated between porphyroblasts on the scale of a hand sample; however, the character of the Ca, Mn, and Y zoning patterns in garnet vary within single layers on the meter-scale. Within a hand sample, individual compositional zones can be correlated from crystal to crystal on the basis of chemical similarities (e.g., intricate yet identical variations in calcium concentration; equivalent manganese concentrations at zone boundaries) and textural similarities (e.g., initiation of inclusiontrail curvature). These relationships allow the identification of individual compositional zones as time markers during garnet growth. Detailed examination of garnet growth zoning patterns, in combination with measurements of inclusion-trail curvature within garnet porphyroblasts and detailed thermodynamic models of the garnet growth history in selected samples, together with an assumed heating rate associated with Alpine metamorphism, allows quantification of strain-rates during prograde amphibolite-facies metamorphism along the northern margin of the Lucomagno nappe. Constraints on the nucleation and timing of garnet growth and garnet growth rate mechanisms permit further insight into the relationship between strainrate and metamorphism at Passo del Sole than had previously been possible with this method: variations in strain-rate magnitude of over a factor of ten (10⁻¹⁴ - 10⁻¹³ s⁻¹) are observed, which correlate with core-to-rim changes in compositional zoning. The source of the incredible diversity of compositional zoning patterns in garnet is hypothesized to be open-system infiltration of ephemeral, channelized Ca- or Mn-rich fluids derived from magmatic sources or equilibrated with metamorphic rocks deeper in the section. Stages of garnet growth associated with increased strain rates are also correlated with the high-Ca or high-Mn zones within the garnet porphyroblasts, presumably as the result of strain softening associated with the passage of these fluids. In-situ oxygen isotope analysis using SIMS demonstrates that the changes in majorelement zoning patterns correlate with small shifts in the isotopic composition of garnet. / text

The deposition of boron oxide (B₂O₃) films on silicon substrates is of significant interest in microelectronics for ultrashallow doping applications. However, thickness control and conformality of such films has been an issue in high aspect ratio 3D structures which have long replaced traditional planar transistor architectures. B₂O₃ films are also unstable in atmosphere, requiring a suitable capping barrier for passivation. The growth of continuous, stoichiometric B₂O₃ and boron nitride (BN) films has been demonstrated in this dissertation using Atomic Layer Deposition (ALD) and enhanced ALD methods for doping and capping applications. Low temperature ALD of B₂O₃ was achieved using BCl₃/H₂O precursors at 300 K. In situ x-ray photoelectron spectroscopy (XPS) was used to assess the purity and stoichiometry of deposited films with a high reported growth rate of ~2.5 Å/cycle. Free-radical assisted ALD of B₂O₃ was also demonstrated using non-corrosive trimethyl borate (TMB) precursor, in conjunction with mixed O₂/O-radical effluent, at 300 K. The influence of O₂/O flux on TMB-saturated Si surface was investigated using in situ XPS, residual gas analysis mass spectrometer (RGA-MS) and ab initio molecular dynamics simulations (AIMD). Both low and high flux regimes were studied in order to understand the trade-off between ligand removal and B₂O₃ growth rate. Optimization of precursor flux was discovered to be imperative in plasma and radical-assisted ALD processes. BN was investigated as a novel capping barrier for B₂O₃ and B-Si-oxide films. A BN capping layer, deposited using BCl₃/NH₃ ALD at 600 K, demonstrated excellent stoichiometry and consistent growth rate (1.4 Å/cycle) on both films. Approximately 13 Å of BN was sufficient to protect ~13 Å of B₂O₃ and ~5 Å of B-Si-oxide from atmospheric moisture and prevent volatile boric acid formation. BN/B₂O₃/Si heterostructures are also stable at high temperatures (>1000 K) commonly used for dopant drive-in and activation. BN shows great promise in preventing upward boron diffusion which causes a loss in the dopant dose concentration in Si. The capping effects of BN were extended to electrochemical battery applications. ALD of BN was achieved on solid Li-garnet electrolytes using halide-free tris(dimethylamino)borane precursor, in conjunction with NH₃ at 723 K. Approximately 3 nm of BN cap successfully inhibited Li₂CO₃ formation, which is detrimental to Li-based electrolytes. BN capped Li-garnets demonstrated ambient stability for at least 2 months of storage in air as determined by XPS. BN also played a crucial role in stabilizing Li anode/electrolyte interface, which drastically reduced interfacial resistance to 18 Ω.cm², improved critical current density and demonstrated excellent capacitance retention of 98% over 100 cycles. This work established that ALD is key to achieving conformal growth of BN as a requirement for Li dendrite suppression, which in turn influences battery life and performance.

No description available.

The aim of the project was to study the mineral, chemical and morphological characteristics of the fallout dust samples. The dust fallout samples were collected at five different sites following the internationally accepted standard procedure for collection and analysis, South African National Standard and American Standard for Testing Methods (ASTM) D1739-98 (2010). Passive single buckets containing ¾ of distilled water and 10.0 ml of sodium hypochlorite (NaOCl) solution, hoisted at a height of about 2.5 m were exposed from March – June 2013 and were collected every month, taken to the laboratory for characterization. First, the samples were filtered and mass concentrations per month were gravimetrically measured. The samples were then prepared for further characterization by the MicroScan Particle Analyser (MSPA)(Microscope UOP UB 100j) which measured the mineral content and the Scanning Electron Microscope - Energy Dispersive X- ray (SEM - EDX) measured the images of different particles (size, shape) and their elemental content. The results from the MicroScan analysis showed the prevalence of sandy rounded-shaped quartz (SiO2) particles across all sites. Minerals detected within the crustal material at all sites were quartz (SiO2), haematite (Fe; Fe2O3; Al2O3), feldspar (Na, K, Mg, Ca: AI2Si2O8), garnet (SiO4), aluminium silicates (AI2Si2O8) and calcium hydroxide [Ca (OH)2]. Evidently, sites A, B and C dominated the abundance of these minerals. On the other hand, sites D and E showed fine and rounded quartz and quartzite with various trace metal oxides. Measured elements in decreasing concentrations were Si, Ca, P, Al, K, S, Fe, Cu, Ti and Mg. Both coarse particle (2.5 - 10.0 μm) and fine particle sizes ranges (< 1.0 to 2.5 μm) were detected. Large irregular shaped particles sizes were common and were linked to crustal material. The results provide good baseline information which requires further characterization of samples by different analytical techniques and validation of possible sources. The ICP-MS was used to determine the elemental composition of dust fallout and the mean concentration of the elements of concern ranged from 1.1 - 2.6 for As, 0.2 - 0.6 for Cd, 17.0 - 21.9 for Ni, 449.8 - 751.1 for Pb, 9.9 - 22.3 for V and 101.7 - 293.0 μg/m3 for Zn. The elements such as Cd exceeded the set limit 0.005 μg/m3 by OSHA (2015) and NIOSH (2007); Pb exceeded the set standard of 0.5 μg/m3 set by OSHA (2015), NIOSH (2007), WHO (2000), USEPA (2012) and DEA (2013). The rest of the elements fell within the set guidelines by various regulatory national and international bodies. The study concludes that, although, all the sampling sites recorded the dust fallout rates within the SANS 1929 (2011) and DEA (2013) average RESIDENTIAL limit of 600 mg/m2/day, the future accumulation and exceedances cannot be ruled out owing to the increasing developments in urban areas / Environmental Sciences / M. Sc. (Environmental Science)

Bohemian garnets have been known as a jewellery stone for many centuries. There is still a lot of interest in them, however, the reserves in traditional locations are getting smaller. That is why search for alternative source of similar garnets in gem quality started. Shavaryn Tsaram deposit in Mongolia is considered as one of the potential sources. Pyrope samples from eight Bohemian localities of two areas (České středohoří [The Central Bohemian Uplands] and Podkrkonoší [The Giant Mountains]) and from Shavaryn Tsaram deposit in Mongolia were analysed using electron microprobe, LA-ICP-MS, ICP-OES, Mössbauer spectroscopy and x-ray powder diffraction. The data were compared with the conclusion that the Mongolian garnets from Shavaryn Tsaram deposit are so different from the Bohemian ones that it will not be possible to use them as a gem material of similar qualities. Bohemian garnet can be characterised as a red garnet with refraction index 1.747 (+/- 0.001) with dominant pyrope component of the average composition Py78Alm17Gr5 and Cr2O3 content above 1 wt.%. The data were also evaluated from two classification schemes point of view. The schemes by Schulze (2003) and Grütter (2004) are used in determining source materials and in diamond prospection. According to them source rocks of Bohemian garnets...