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

Prostaglandin E₂ (PGE₂), the most abundant prostaglandin in mouse skin, has been shown to promote skin tumor development. EP1 is one of four PGE₂ receptors. EP1 mRNA levels analyzed by a quantitative real-time polymerase chain reaction were increased after treatments of 12-O-tetradecanoylphorbol 13-acetate (TPA) or ultraviolet light on skin as well as in 7,12 dimethylbenz[a]anthracene (DMBA)/TPA or UV-induced skin tumors. To determine whether the EP1 receptor levels affect skin tumor development, we generated BK5.EP1 transgenic mice which overexpress EP1 in the basal layer of the epidermis. The skins of these mice are histologically indistinguishable from wild type mice. To determine the role of EP1 in skin tumor development, a DMBA/TPA skin carcinogenesis protocol was used. EP1 transgenic mice had a reduced tumor multiplicity and a reduced tumor incidence compared to wild type mice, but had a higher papilloma to carcinoma conversion rate. In a DMBA-only skin carcinogenesis protocol, EP1 transgenic mice developed more tumors than wild type mice. The effect of EP1 on cell proliferation was measured in vivo. After TPA treatment, cell proliferation was induced in both EP1 transgenic mice and wild type mice to a similar extent. However, 5 days after DMBA treatment, there were about 2-fold more proliferating cells in the basal layer of the epidermis of EP1 transgenic mouse skin than in wild type mice. To confirm that the enhanced tumor formation in transgenic mice is in fact PGE₂ dependent, EP1 transgenic mice were administered the selective cyclooxygenase-2 inhibitor Celecoxib or a control diet starting 1 week before DMBA treatment. Surprisingly, there was no lesion development on mice that were fed Celecoxib. Histological sections of skin from Celecoxib-fed mice showed a fairly normal skin histology 2 weeks after DMBA treatment compared to the pronounced pseudocarcinomatous hyperplasia observed in control diet mice. Therefore, it can be concluded that EP1 signaling increases PGE₂ production through COX-2 induction and promotes tumor development. / text

Magister Scientiae - MSc (Earth Science) / The complexity of the Platreef stratigraphy and the generic position of the Ni-Cu-PGE mineralisation is a challenge to prospecting and mining companies in the Northern Limb of the Bushveld Complex, partially, as a result of various floor rock interactions with the reef. Therefore, this study evaluated the effects of contact metasomatic fluids on the nature and style of PGE mineralisation as the main event leading to the complexity of the Platreef stratigraphy from the contact zone near the floor rock. Fifty samples from boreholes MO009 and MO019 drilled at Moordkopje 813 LR farm for Akanani Project by Lonmin Plc were used for this study. The mineralogy and geochemistry of the Platreef samples were studied and associated with their mineralisation occurrences. Major, minor and trace element contents were analysed by XRF analysis using fused beads, and PGE contents (Pt, Pd) in 11 samples were determined by Fire Assay.

Abstract Sulfide-poor deposits of platinum-group elements (PGE) occur in two main types: silicate-type and oxide-type. In the silicate-type mineralization PGE form discrete platinum-group minerals (PGM) that occur as inclusions in various silicate minerals. In the oxide-type mineralization PGM may have different modes of occurrence. They may be associated with silicates or they may occur as inclusions in chromite, magnetite or ilmenite, for example. In some cases they may even be associated with base metal sulfides. The approach chosen in this work is mainly a mineralogical one. PGM parageneses, their modes of occurrence and associations with other minerals were studied from different deposits. These are then compared to some well-recorded examples of PGE deposits. The case studies presented, the Duluth Complex in Minnesota, U.S.A., the Hanumalapur Complex in Karnataka, India, and the Penikat Layered Intrusion in northern Finland, are examples that illustrate the multitude of possibilities regarding PGE mineralization versus the traditional approach where any significant quantities of PGE are supposed to occur only in association with base metal sulfides. As the traditional orthomagmatic and hydrothermal models cannot explain the genesis of some sulfide-poor PGE occurrences, a new theory of PGE mineralization was developed. This “redox theory” is an attempt at explaining the association of PGE with various oxide minerals, most importantly chromite.

Please read the abstract in the section 00front of this document / Thesis (PhD)--University of Pretoria, 2009. / Geology / unrestricted

The base metal distribution in, and losses to, Anglo Platinum six-in-line and slag cleaning furnace slags were characterised to coincide with various process changes at Waterval Smelter from 1999 to 2009. The base metals are presumed to be reliable indicators of PGE losses and are easier to detect and measure than these elements are. In addition, base metal and sulphur levels are used to monitor and control many smelter processes, including slag cleaning and converting. Some losses to slag are recoverable but others are not – these have been quantified during this study. Slag composition and smelting temperatures have varied substantially, and optimisation of the slag cleaning furnace – a first for the South African platinum industry – has produced a wide variation in oxidation conditions. Most of the base metal losses in the slag cleaning furnace are mechanically entrained matte particles, the largest of which should be recovered. These have been examined to establish any relationship between composition, size, and depth within the furnace so that recommendations can be made to limit these types of losses. In the six-in-line furnaces, over half of base metal losses to slag are as dissolved phases, which are not recoverable. Levels of dissolved metals have been measured and related to furnace operating conditions and slag composition. The prediction of such base metal losses is not easy, because the slag compositions are so complex. One aspect of the project has been to compare the measured distribution of the base metals with those calculated using the FactSage equilibrium model, to identify problem areas, and to recommend actions which could improve the predictions of this and similar modelling programs for base metal dissolution in slag. New electron microbeam techniques have been developed to quantify base metal distribution in slag, and novel combinations of these techniques with analytical chemistry and Mössbauer Spectroscopy have been pioneered. / Dissertation (MSc)--University of Pretoria, 2009. / Materials Science and Metallurgical Engineering / unrestricted

No description available.

Anforderungen sind ein Kernbestandteil agiler Entwicklung und aufgrund der Charakteristika mechatronischer Systeme ist eine Bündelung von Anforderungen zur Realisierung von Entwicklungsgenerationen als Inkremente wirtschaftlich sinnvoll. Folglich ist ein Management der Anforderungen hinsichtlich ihrer Entwicklung, Verifizierung und Wiederverwendung notwendig. Anhand der Entwicklung von Werkzeugmaschinen werden die beobachteten Charakteristika der Entwicklung mechatronischer Systeme mit Einfluss auf Durchlaufzeit, Materialkosten und Aufwand beschrieben, diese sind: Fertigungsdokumentation, Bestellung, Lieferung, Hilfsmittel, Montage und Inbetriebnahme. Unter Berücksichtigung dieser Einflussfaktoren wird anschließend ein Vorgehen zur systematischen Wiederverwendung von Anforderungen bei der Entwicklung neuer Produkt- und Entwicklungsgenerationen von Werkzeugmaschinen vorgestellt. Dabei werden Qualitätsanforderungen, funktionale Anforderungen und Randbedingungen unterschieden. Für Qualitäts- und funktionale Anforderungen werden spezifische Vorgehensweisen im Rahmen der Realisierung einer Entwicklungsgeneration vorgeschlagen. Während die Erfüllung von Qualitätsanforderungen für eine Entwicklungsgeneration nach der Realisierung abzuprüfen ist, sind funktionale Anforderungen direkter Ausgangspunkt von Entwicklungsaktivitäten in einem Sprint. Randbedingungen werden als Begründung für Anforderungen nachvollziehbar und wiederverwendbar dokumentiert. Wesentliche Bestandteile des Vorgehens wurden in Jira implementiert und im Rahmen zweier Entwicklungsprojekte positiv evaluiert.

Large Igneous Provinces (LIPs) form during short-lived pulses of extensive magmatic activity. LIPs are known for their ability to affect global climate as well as for their Ni-Cu-PGE ore potential. A key factor that controls the intensity of the climate impact of a LIP and its ore potential is the assimilation of volatile-rich sedimentary host rocks. Magmas of the High Arctic Large Igneous Province (HALIP), exposed in the Arctic, intruded volatile-rich black shales, carbonates and evaporites in the Canadian Arctic Islands, offering a great opportunity for studying magma-sediment interaction. The purpose of this study is to test whether assimilation of sedimentary sulphide can promote sulphide immiscibility in magma and thus aid formation of Ni-Cu-PGE ore bodies. This is done by analysing sulphur isotopes in pyrite grains hosted in a HALIP dolerite sill, which was emplaced into black shale, by using Secondary Ion Mass Spectrometry (SIMS). Four dolerite samples are analysed; two coming from the lower contact margin of the sill, one from 60 cm into the sill and one sample from a basaltic vein at the upper contact margin of the sill. A total of 14 pyrite grains (n = 246 individual SIMS spot analyses) were analysed for their sulphur isotope ratios. The results of the SIMS analyses show that all analysed sulphides have highly negative δ34S values ranging from -19.5 to -5.7‰ (average δ34S = -8.2 ± 0.83‰, 2SD), which therefore differ largely from that of the primitive mantle (0 ± 1.8‰). In order to put our four analysed dolerite samples into a broader context, δ34S data of our sulphides are compared with whole-rock δ34S and δ18O data from Hare Fiord shale and dolerite samples. The δ34S values of the sulphide samples from the sill typically trend toward the negative sulphur isotope composition of the sulphides in the surrounding shale, and the shale surrounding the sill experiences a loss of 32S near the contact of the sill. This indicates that sedimentary light sulphur (32S) has been locally incorporated into the sill by the surrounding shale, resulting in negative δ34S values in the magmatic sulphides. Since sulphide immiscibility in the Hare Fiord sill was triggered by assimilation of sulphur from host rock shale, the igneous rocks of the HALIP may be prospective for Ni-Cu-PGE mineralization, though more studies are needed. Furthermore, our results suggest that incorporation of crustal sulphur increased the volatile budget of HALIP magmas, which therefore could have contributed to a deterioration of the environmental conditions during the emplacement of the HALIP. / Stora magmatiska provinser (på engelska Large Igneous Provinces, LIPs) är vulkaniska event då enorma mängder magma avsätts över en väldigt stor yta under ett, i ett geologiskt perspektiv, kort tidsspann. Dessa stora vulkaniska utbrott har väckt stort intresse då de är samtida med flera av de största massutdöendena i jordens historia, men också för att en viss typ av sulfidmalm rik på nickel, koppar och platinametaller (Ni-Cu-PGE malmer) ofta förekommer i provinsernas magmagångar och magmakammare. En viktig faktor som till stor del avgör en magmatisk provins påverkan på klimatet och potentiella malmförekomster är inkorporering av sedimentära bergarter till magman som, när de hettas upp, kan frigöra gaser rika på svavel och kol. I Kanadas arktiska öar trängde magma tillhörande den högarktiska magmatiska provinsen (HALIP) in i svart skiffer, karbonater och evaporiter, som är sedimentära bergarter rika på flyktiga ämnen. Denna magmatiska provins erbjuder därför stora möjligheter till att studera interaktionen mellan magma och sedimentära bergarter. Syftet med denna studie är att testa om inkorporering av sedimentärt svavel kan främja bildandet av sulfidsmälta i magma och därigenom bidra till bildandet av sulfidmalmer. Detta görs genom att analysera svavelisotoper i sulfidmineral i prover från en magmagång, som trängde in i en skifferformation, tillhörande den högarktiska magmatiska provinsen i norra Kanada. Genom att analysera svavelisotopkvoten (δ34S) i sulfidmineral kan man få information om huruvida svavlet i mineralen är av sedimentärt ursprung (där skiffer generellt har negativa δ34S värden) eller om svavlet har δ34S värden liknande de från manteln (som har δ34S värden runt 0‰), vilket i så fall skulle innebära att magman inte har inkorporerat sedimentärt svavel. Genom att använda masspektrometri av typen SIMS analyseras totalt 14 sulfidmineralkorn (n = 246 individuella SIMS punkter) för deras svavelisotopkvoter. Resultatet av studien visar att alla analyserade sulfidmineral har mycket negativa δ34S värden mellan -19.5 och -5.7‰ (med ett δ34S medelvärde på -8.2 ± 0.83‰, två standardavvikelser). Genom att jämföra våra δ34S värden med δ34S och δ18O värden för andra prover från både magmagången och den omgivande skiffern kunde vi se att δ34S värdena för sulfidmineralen i de yttre delarna av magmagången har liknande negativa värden som den omgivande skiffern, och att δ34S värdena för skiffern närmast magmagången är mer positiva. Detta tyder på att sedimentärt svavel i kontakten mellan magmagången och skiffern har blivit inkorporerat i magman från den omgivande skiffern. Våra resultat tyder därför på att sulfidmineralen i våra prover från magmagången bildades genom assimilering av svavel från den omgivande skiffern. Detta innebär i sin tur att den kanadensiska högarktiska magma provinsen potentiellt kan vara en källa för sulfidmalm, även om ytterligare studier behövs. Dessutom visar våra resultat att inkorporering av sedimentärt svavel förmodligen ökade de vulkaniska gaserna i magman, vilket kan ha bidragit till klimatförändringar relaterade till den vulkaniska aktiviteten av den högarktiska magmatiska provinsen.

In der Frühen Phase der PGE-Produktgenerationsentwicklung werden Entscheidungen unter einem hohen Grad an Unsicherheit getroffen. Gleichzeitig haben diese Entscheidungen einen bedeutenden Einfluss auf den späteren Markterfolg von Produkten. Somit ist eine frühzeitige und kontinuierliche Validierung für den Erfolg zukünftiger Produkte notwendig. In diesem Beitrag wird ein Ansatz präsentiert, der es erlaubt, grundlegende Produkteigenschaften in der Frühen Phase der PGE-Produktgenerationsentwicklung zu beschreiben und zu modellieren. Des Weiteren werden die unterschiedlichen Beschreibungsmodelle analysiert und miteinander verglichen. Anschließend wird veranschaulicht, welche Modelle und Technologien genutzt werden können, um die gewünschten Produkteigenschaften zu validieren. Im Hinblick auf die Validierungsmethode bestimmen die Ergebnisse einer durchgeführten Expertenbefragung die Relevanz von einzelnen Umfeldern. Abschließend wird eine szenariobasierte Methode zur Validierung von Produktprofilen angeleitet und auf Grundlage eines konkreten Produktprofils bewertet.