Le travail présenté dans ce manuscrit consiste en une contribution à l'étude de ces structures RTM par microscopie Raman, afin de mesurer certains paramètres tel que la réticulation, l'identification de composés chimiques, les contaminations, l'homogénéité d'additifs... mais aussi sur l'utilisation de ces mesures dans le cadre d'une modélisation numérique de ces structures. Cette Thèse de Doctorat s'inscrit dans un programme pour le remplacement des mesures actuelles intrusives, destructives et indirectes par une mesure in situ via un capteur Raman implanté dans l'outillage et à la construction du système en milieu industriel. Avec comme but d'optimisation par exemple les procédés de fabrication des pales d'éolienne, ponts de bateaux de garantir et valider des critères de qualité des pièces techniques à forte valeur ajoutée et enfin d'optimiser les caractéristiques physico-chimiques liées à la mis en œuvre dans l'outillage.

Agro-biodiversity in the desert oases of Baja California, Mexico is a product of isolation and integration through time and across the various spaces of the peninsula. The oases hold heirloom perennial crop species first introduced by Jesuit missionaries (1697-1768) and represent geographies of historical dissemination. I selected fifteen Jesuit mission oases and surveyed the oasis gardens for species richness and abundance. To understand the cultural, political and economic forces that create these patterns of persistence within the oases, I conducted interviews on farming system practices, geographical remoteness, market integration, land tenure, tourism, protected area status and cultural practices. In all, I surveyed 241 gardens and documented eighty-nine total perennial crop species. Historical records in 1774 describe twenty-one perennial crop species in cultivation after the Jesuit expulsion. I calculated species-area relationships and rank-abundance for total perennial and mission crop species in each oasis and inventory comparisons for those oases with quantitative historical data to analyze retention of historic mission species. A high persistence of mission species indicates that oases serve as agro-biodiversity refugia, or protected source areas for agricultural species. These mission-oases act as a network of interconnected sites that are also isolated from one another and the Mexican mainland by the rugged environment, limited transportation infrastructure, and by sea. Within the network, these fifteen oases span a range of small and hours distant from the nearest resource center, to fully urbanized with international ports and airports. I describe how phases and processes of isolation and connectivity shape and transform the agro-biodiversity profiles in this archipelago of peninsula oases.

In order to continue with metal-oxide-semiconductors (CMOS) transistor scaling and to reduce the power density, the channel should be replaced with a material having a higher electron mobility, such as a III-V semiconductor. However, the integration of III-V's is a challenge because these materials oxidize rapidly when exposed to air and the native oxide produced is characterized by a high density of defects. Deposition of high-k materials on III-V semiconductors using Atomic Layer Deposition (ALD) reduces the thickness of these oxides, improving the semiconductor/oxide interface quality and the transistor electrical characteristics. In this work, ALD is used to deposit two dielectrics, Al₂O₃ and TiO₂, on two III-V materials, GaAs and InGaAs, and in-situ X-ray photoelectron spectroscopy (XPS) and in-situ thermal programmed desorption (TPD) are used for interface characterization. Hydrofluoric acid (HF) etching of GaAs(100) and brief reoxidation in air produces a 9.0 ± 1.6 Å-thick oxide overlayer containing 86% As oxides. The oxides are removed by 1 s pulses of trimethylaluminum (TMA) or TiCl₄. TMA removes the oxide overlayer while depositing a 7.5 ± 1.6 Å thick aluminum oxide. The reaction follows a ligand exchange mechanism producing nonvolatile Al-O species that remain on the surface. TiCl₄ exposure removes the oxide overlayer in the temperature range 89°C to 300°C, depositing approximately 0.04 monolayer of titanium oxide for deposition temperatures from 89°C to 135°C, but no titanium oxide is present from 170°C to 230°C. TiCl₄ forms a volatile oxychloride product and removes O from the surface while leaving Cl atoms adsorbed to an elemental As layer, chemically passivating the surface. The native oxide of In(0.53)Ga(0.47)As(100) is removed using liquid HF and gas phase HF before deposition of Al₂O₃ using TMA and H₂O at 170°C. An aluminium oxide film with a thickness of 7.2 ± 1.2 Å and 7.3 ± 1.2 Å is deposited during the first pulse of TMA on liquid and gas phase HF treated samples, respectively. After three complete ALD cycles the thickness of the aluminum oxide film is 10.0 ± 1.2 Å on liquid HF treated and 6.6 ± 1.2 Å on gas phase HF treated surfaces. Samples treated with gas phase HF inhibit growth. Inhibition is caused by residual F atoms that passivate the surface and by surface poisoning due to the thicker carbon film deposited during the first pulse of TMA. On InGaAs covered by native oxide, the first TMA pulse deposits 9 Å of aluminum oxide, and reaches saturation at 13 Å after 15 pulses of TMA. The film grows by scavenging oxygen from the substrate oxides. Substrate oxides are reduced by the first pulse of TMA even at 0°C. At 0°C, on a 9 Å thick Ga-rich oxide surface, 1 pulse of TMA mainly physisorbs and a limited amount of aluminum oxide is deposited. At 0°C, 110°C, and 170°C, more aluminum oxide is deposited on surfaces initially containing As oxide, and larger binding energy (BE) shifts of the O 1s peak are observed compared to surfaces that contain Ga oxides only, showing that As oxides improve the nucleation of Al₂O₃.

<p>While much is known about the abundance and genetic diversity of environmental microbial communities, little is known about their taxon-specific activity. In this thesis I address this gap using a model marine microbe, the cyanobacterium <italic>Prochlorococcus spp.</italic>, which numerically dominates tropical and subtropical open oceans and encompasses a group of genetically defined clades that are ecologically distinct. Ribosomal RNA is a promising indicator of in situ activity because of its essential role in protein synthesis as well as its phylogenetic information, which could be used to distinguish clades among mixed populations. Here I show that, in a laboratory system the specific growth rate of representative <italic>Prochlorococcus</italic> strains could be quantitative predicted from cellular rRNA content (assessed by RT-qPCR), cell size (assessed by flow cytometry) and temperature. Applying this approach in the field, I show unique clade-specific activity patterns for <italic>Prochlorococcus</italic>. For example, vertically within the euphotic zone, eHL-II activity is strongly impacted by light and is consistent with patterns of photosynthesis and on a horizontal transect from Hawaii to San Diego, eHL-I and eHL-II activities exhibit significant transitions and appear to be regulated by temperature, nutrient and vertical mixing gradients. Using ribosomal tag pyrosequencing of DNA and RNA, I have extended our observation to the Eubacterial community and described the biomass distribution (rDNA) and activity (rRNA) patterns from two representative depths (25 and 100 m) at a well-studied oligotrophic ocean station. These results show that for some populations the abundances and activities are significantly uncoupled, which suggests substantial top-down controls or physical transport processes. Further exploring the taxon-specific activity patterns along with abundances and environmental variables across time and space is essential to better understanding the dynamics of a complex microbial system as well as predicting the consequences of environmental change.</p> / Dissertation

Ingeniero Civil de Minas / La realización de esta memoria de título, consiste en evaluar la explotación de los yacimientos Quetena y Toki, utilizando lixiviación de caserones. El proyecto se evalúa a nivel de ingeniería de perfil, lo que implica que se utilizaron antecedentes de otras minas, con aspectos similares a la operación de esta, y el grado de detalles permite obtener un primer acercamiento a una aplicación a gran escala de este método. El método de explotación denominado lixiviación de caserones, consiste en la irrigación de soluciones a través del mineral quebrado, mediante tronadura. Lo cual permite un control adecuado de la lixiviación, al generar una diferencia de permeabilidad entre la roca in situ y el material tronado. Una vez captadas las soluciones por la base del caserón, el cobre es recuperado en las plantas de SX EW de manera convencional. Los yacimientos Toki y Quetena, lugar donde se está evaluando el método, se encuentran a menos de 5 km de Calama. Los cuerpos están cubiertos bajo una capa de gravas estériles, de un espesor que varía entre los 40 a 150 m, y la explotación se centró solo en la lixiviación de los óxidos presentes, cuyas reservas superan los 500 MTon a una ley de 0.42 %. La metodología consiste en el estudio de un proyecto minero, el cual contempla la realización de los siguientes análisis: diseño de la unidad básica de explotación, estimación de costos e inversión, determinación del ritmo óptimo de explotación, planificación y evaluación económica. Todo esto con la finalidad de determinar si el proyecto es rentable tanto técnica como económicamente. El diseño elegido comprende la construcción de caserones tipo sublevel stoping de 80 metros de alto, 100 metros de largo y 40 metros de ancho en el caso de los caserones primarios y 60 metros de ancho en el caso de los caserones secundarios. Los aspectos determinantes que permiten una operación rentable son: una baja inversión de capitales, debido a que no se requiere la construcción de plantas de procesamiento de minerales, el costos de transporte de mineral, el cual considera solo la extracción del esponjamiento a un ritmo de 12,000 Ton/día, pero lixiviando 60,000 Ton/día, y el costo total a cátodo de 2.3 US$/lb que hace rentable al proyecto. El proyecto de explotación resulta rentable, obteniendo un VAN de 171.2 MUS$ con una inversión de 200.1 MUS$, lo cual es más rentable económicamente que la explotación por rajo abierto.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.