京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22011号 / 工博第4623号 / 新制||工||1720(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 酒井 伸一, 教授 高岡 昌輝, 准教授 平井 康宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

This diploma thesis focuses on the design of three portfolio variants for a fund of qualified investors operating in the Czech Republic, which focuses on investing in shares of Exchange Traded Funds investing in precious metals.

<p> Freegold Mountain is part of a northwesterly trending volcanoplutonic arc comprising the eastern portion of the Yukon Crystalline Terrane. Plutonic rocks in the area intrude Paleozoic metasediments and consist of a Late Triassic to Early Cretaceous granodiorite intruded by the Big Creek Syenite dated at 138 ± 10 Ma. A suite of K-rich intrusive volcanic rocks comprise an early period of basalt-andesite-dacite volcanism and a later rhyolitic volcanism dated at 78 ± 6 Ma. Volcanic rocks at Freegold Mountain can be correlated with Mt. Nansen Volcanics.</p> <p> Two sets of fracture planes, oriented at 165/70E and 18/80W, show dextral and sinistral displacement, respectively. Rhyolite dykes and gold-quartz veins predominantly oriented NNE have been emplaced along the 18/80W extensional fracture systems. These fractures may be modelled as high-angle Reidel shears, although evidence indicates that fracture orientations and fault movement have been complicated by changing stress fields from middle Cretaceous to Tertiary time.</p> <p> The gold-bearing quartz veins at Freegold Mountain are high grade, low-tonnage deposits with grades ranging from 0.4 to 1.0 oz/t. Fluid inclusions from the lower portions of the Laforma mine homogenize at 185° C with salinity ranging between 2 and 4.5 wt. % NaCl equivalent. A boiling zone has been detected above the deeper ore where fluid inclusions show extreme ranges in homogenization temperatures (165-430° C) and salinity (4 - 43 wt. % NaCl). Fluid inclusion waters have stable isotopic signatures indicative of meteoric water with 𝛿D = -138 and 𝛿^18O = -18.4. Boiling of the Laforma fluid has caused a shift towards heavier hydrogen and oxygen isotopic values, mineral deposition and appears to enhance gold precipitation over non-boiling zones. Stable isotopic evidence indicates that the paleolatitude of Freegold Mountain during late Cretaceous time was south of the present day Yukon-B.C. border.</p> <p> The Emmons Hill (Dart) prospect is a gold-bearing vein-breccia with a mineral assemblages of barite, stibnite, marcasite, cinnabar, orpiment, Fe and Mn carbonates and chalcedonic silica. Fluid inclusions from these deposits homogenize between 140-185° with salinities of 0-0.5 wt. % NaCl. This property shows marked similarities to acid-sulphate type precious metal deposits in New Zealand and western United States.</p> <p> Large (x to xx Mt) northwesterly trending diatremes appear to be structurally controlled by small transcurrent faults parallel to and coeval with displacement along the Tintina fault. The Antoniuk diatreme (3.7 Mt @ 1.14 g/t Au) consists of heterolithic and monolithic breccias intruded by dacite and rhyolite dykes. Diamond drilling indicates that a large body of fine to medium grained alaskite is present beneath the auriferous breccia. The deposit formed by the explosive escape of volatile components evolved from the retrograde boiling of a silicic magma chamber. Gold mineralization in the breccia is associated with pyrite and arsenopyrite formed at temperatures around 300°C and salinities of about 4.5 wt. % NaCl.</p> / Thesis / Master of Science (MSc)

As our world continues to develop and contend with the impacts of climate change, the scale up renewable energy technologies has never been more urgent. Alternative fuels derived from biomass-derived oxygenates and water splitting offer promising solutions for the transition towards sustainable chemical feedstocks and integration of clean renewable energy sources. However, this technology continues to be hampered by the need for scarce and costly precious metal catalysts. The work done in this thesis explored the facet-dependence of glycerol electrooxidation and studied the application of earth-abundant transition metal carbides (TMCs) and nitrides (TMNs) for reducing precious metal catalyst loadings in water electrolysis and electrooxidation of methanol and glycerol. Glycerol valorization has drawn significant interest in recent years due to the growth in biodiesel production leading to the market saturation of glycerol. While this molecule can be converted into a variety of value-added products, the possibilities have been limited by poor selectivity for C-C bond scission. The breaking of the C-C bonds in glycerol allows for complete extraction of energy from the molecule via complete glycerol oxidation, thereby opening the door for utilizing glycerol as an electrochemical fuel. While platinum (Pt) has been among the most popular catalysts, its tendency for poisoning due to adsorbed CO has hindered its activity. Previously demonstrated to enhance the catalytic activity of platinum (Pt) by reducing CO binding energy and increasing C-C bond scission selectivity in ethanol electrooxidation, TMCs were employed as catalyst supports for the glycerol electrooxidation reaction. This work used electrochemical techniques and in-situ IRRAS to study various loadings of Pt/TaC and Pt/WC to find enhanced C-C bond scission activity at reduced Pt loading because of the synergistic effects between Pt and TMCs. While Pt has remained the benchmark catalyst for glycerol electrooxidation due to its high C-C scission activity, gold (Au) has also found popularity with its high catalytic activity attributed to greater resistance to CO poisoning, despite its favorability for partial glycerol oxidation. Previous studies have hinted at the significance of Au surface facets on glycerol oxidation activity and product selectivity, but none had used nanoparticles with controlled surface facets. This thesis sought to bridge the knowledge gap using precisely-synthesized Au nanocrystals with well-characterized {100}, {110}, and {111} surface facets to provide insight into glycerol electrooxidation on Au. Electrochemical techniques were used in parallel with in-situ IRRAS analysis to uncover the differences in product selectivity and oxidation activity between the three Au surfaces, with Au {111} exhibiting the greatest activity for C-C bond scission, while Au {110} showed the lowest onset potential due to facile AuOH- formation. Hydrogen (H₂) fulfills a critical role in modern society, not only as a renewable fuel, but also as a key chemical feedstock. Production of H₂ from water electrolysis creates opportunities for storing excess energy from renewable sources as an energy-dense fuel and reducing the environmental footprint of chemical processes requiring H₂. However, efforts have been hampered by the dependence on scarce Pt-group catalyst materials. This thesis explores the application of TMNs as an earth-abundant material for enhancing the activity of Pt in the hydrogen evolution reaction (HER). Combined with DFT calculations, the HER activity of monolayer Pt- and Au-modified TMN thin films was correlated with the ΔGH* values in a volcano-type relationship. Electrocatalytic experiments in acidic electrolyte showed that TMN-supported monolayer Pt exhibited similar HER activity to the Pt foil, correlating with intermediate hydrogen adsorption strength. TiN-supported Pt and Au powders were studied to extend the correlations from thin films. Furthermore, the electrochemical stability of TMNs was studied across a wide range of potentials and pH values to generate pseudo-Pourbaix diagrams and identify TMN candidates for HER, alcohol oxidation, ORR and OER applications. Using the pseudo-Pourbaix findings, Pt/TMN catalysts were selected for studying methanol electrooxidation activity. Methanol electrooxidation has drawn significant attention particularly due to interest in direct alcohol fuel cells. Much like the case for glycerol oxidation, while Pt has been the benchmark catalyst, it has been hindered by strong adsorption of CO. As the modification of Pt with other materials, such as ruthenium, has shown promising enhancements to methanol electrooxidation activity, the synergistic effects of Pt modification with TMNs were studied in this work. In the resulting electrochemical experiments, Pt/Mo₂N was found to exhibit negligible activity likely because of its oxidative instability. In contrast, Pt/TiN showed enhanced activity, and in-situ IRRAS experiments suggest that Pt/TiN enhanced the COads-free pathway leading to increased formic acid selectivity. This thesis demonstrated avenues for developing more optimized catalysts with reduced loadings of Pt and other precious metals for applications in alternative fuel production and utilization. The influence of Au surface facets on glycerol oxidation was examined and the synergistic effects between Pt and earth-abundant TMC and TMN materials were used to enhance the electrooxidation of biomass-derived oxygenates and H₂ production from water electrolysis. These electrochemical stability and activity trends can guide future catalyst design for other critical reactions such as oxygen evolution and challenging applications like glycerol electroreduction.

Adsorption mechanisms of modified thiol collectors on gold, silver, and gold-silver alloys have been studied and compared with those of ethyl xanthate (EX). The modified thiol collectors include dicresyl monothiophosphate (DCMTP), dialkyl dithiophosphinate (DTPI) and monothiophosphinate (MTPI). In general, the adsorption mechanisms on silver and gold-silver alloys can be explained by the EC-mechanism involving an electron transfer step and a chemical reaction step. Thus, the adsorption should be controlled by the Eh of the electrochemical oxidation of the electrode involved and the pK of the metal collector complex. According to this mechanism, DCMTP should adsorb on silver and gold-silver alloys at a lower potential than DTPI and MTPI since the pK of silver-DCMTP complex is larger than those of silver-DTPI and silver-MTPI. This has been verified to be the case by voltammetry, FTIR and contact angle studies. Likewise, EX adsorbs on silver at a lower potential than the modified thiol collectors because the pK of silver-EX is larger than those of the silver-modified thiol collectors. Both EX and the modified thiol collectors adsorb on silver at lower potentials than on the gold-silver alloys, which can be attributed to the lower activity of silver on the alloy surface. For the same reason, the potential for the onset of collector adsorption on alloys decreases with increasing silver content. / Ph. D.

The search for mineral deposits is a time consuming, risky and very expensive process. Applying new models and methods provides a competitive advantage in the search for mineral deposits because an explorationist can quickly evaluate potential targets and eliminate areas without good potential for mineralization. This dissertation presents a practical technique for prediction to finding precious metal mineralization at Guanajauato mining district (GMD) base on theoretical and experimental studies of fluids properties, mineral phase equilibrium, physical and chemical mechanisms. Making the technique highly transportable so that it can be applied in the field during an exploration program base on petrographic characteristics of mineral textures produced during boiling events in quartz, calcite and adularia, and fluid inclusions contained in these phases. While this work was conducted in GMD, the results should be applicable in exploration for epithermal deposits worldwide. The GMD is one of the largest silver producing districts in the world. Ore shoots are localized along three major northwest trending vein systems, the La Luz, Veta Madre and Vetas de la Sierra. More than 1200 samples were collected from surface outcrops, underground mine and historical and recent drill core. Traverses perpendicular to veins in all system were also conducted. Most of the samples (approximately 90%) were also assayed for Au, Ag, Cu, Pb, Zn, As, Sb. Samples from the GMD show a wide range in silica textures are indicative of rapid precipitation, such as occurs when fluids boil. Other mineral phases, including illite, rhombic adularia and bladed calcite are also indicative of rapid growth in a hydrothermal system and are characteristic of boiling systems. Because boiling is an effective mechanism for precipitating gold and silver from hydrothermal fluids, the presence of mineral textures indicative of boiling is a desirable feature in exploration. In many samples, textural evidence for boiling is supported by coexisting liquid-rich and vapor-rich fluid inclusions, or Fluid Inclusion Assemblages consisting of only vapor-rich inclusions, suggesting "flashing" of the hydrothermal fluids. Textural and fluid inclusion evidence for boiling has been observed in the deepest levels of the GMD, suggesting that additional precious metal resources may occur beneath these levels. / Ph. D.

Thesis (MBA (Business Management))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: South Africa has historically benefited from its mineral wealth, building one of the leading mining industries in the world. South Africa holds the worlds largest known PGM (or precious group metals) resource base (in a geological formation known as the Bushveld Igneous Complex), with an estimated life of 230 years (at current mining rates). This precious commodity is a precious source of both the direct as well as indirect contributions into the South African economy, as well as a leading source of employment in the South African mining industry. PGMs are predominantly used in auto catalysts, with an estimated 60% of global demand emanating from this application, where the commodity is used in breaking down noxious compounds in exhaust emissions. Given the strong correlation between automotive production and platinum sales, it seems viable to assume that platinum sales will continue to grow as more stringent legislation is introduced globally to reduce automotive emissions. This can currently only be down by increasing the platinum loads in auto catalysts, as alternative technologies are not widely accepted or developed at present. Given the influence (and positive correlation between) demand and prices, it appears that PGM prices will be driven upwards as demand continues to grow. This effect may be exacerbated by the fact that the expansion in demand is likely to outgrow the expansion in supply, given that few significant platinum operations have been started in recent years. Following the strong rally of commodity prices, specifically PGM prices in mid-2008 that saw platinum at a record high of USD2276/oz, major automotive producers have indicated that they are investigating alternatives to the application of precious metals in catalytic converters, in an attempt to curtail production costs. Although no viable substitute could be developed as yet, various alternatives (such as silver alloys) have been mentioned throughout the media. The purpose of this paper is to investigate the impact of such a substitution event on South African PGM producers and its resultant effect on the South African economy. The study will attempt to determine, at a high level, the direct impact of the event, as well as the indirect consequences of the proposed substitution event. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse ekonomie is histories op die mynbou- en landbousektore gebaseer, wat gelei het tot Suid-Afrika se wêreldklas mynbou industrie. Suid-Afrika beskik oor die wêreld se grootste PGM reserwes (in 'n geologiese formasie, ook bekend as die Bosveld Stollings Kompleks), met ‘n geskatte lewe van 230 jaar (teen huidige mynbou tempo's). Die komoditeite is verantwoordelik vir ‘n aansienlike hoeveelheid direkte en indirekte waardetoevoeging tot die Suid-Afrikaanse ekonomie. PGM’s word hoofsaaklik in katalisators in voertuie gebruik, met nagenoeg 60% van wêreldwye vraag wat uit die toepassing voortspring. PGMs word gebruik om uitlaatgasse op te breek en te verwerk in motorvoertuie. Gegewe die hoë mate van korrelasie tussen PGM en voertuigverkope, blyk dit voor die handliggend dat platinumverkope sal aanhou styg soos wat omgewingswetgeging in bepaling van toelaatbare uitlaatgasse in motorvoertuie strenger word. Die vermindering van uitlaatgasse is huidiglik slegs moontlik deur die verhoging van PGM ladings in katalisators, gegewe dat alternatiewe tegnologieë nog nie ver genoeg gevorder is om geimplementeer te word nie. Die hoë mate van korrelasie tussen PGM pryse en PGM vraag dui dat dit hoogs waarskynlik is dat die prys van edelmetaal sal aanhou styg soos wat vraag toeneem. Die verskynsel sal moontlik verder bou op die verwagting dat vraag vir die metaalaanbod oor die langtermyn sal oorskadu, siende dat geen wesenlike nuwe PGM myne onlangs oopgemaak is nie. Voertuigvervaardigers het aangedui dat hul alternatiewe tegnologieë opndersoek, nadat die platinumprys tot 'n rekord hoogtepunt van USD2276/ oz gestyg het in mid 2008. Die uitspraak is gelewer met die oog op koste kontrole in die vervaardiging van motorvoertuie. Alhoewel geen werkbare alternatief vir die edelmetale huidiglik bestaan nie, is verskeie moontlike materiale reeds in die media bespreek (byvoorbeeld verskeie silwer allooie). Die doel van die dokument is om die potensiële impak van so ‘n vervangings senario op die Suid-Afrikaanse ekonomie te ondersoek. Die studie sal poog om op ‘n hoë vlak die direkte en indirekte gevolge van die gebeurtenis te bepaal.

No description available.

A novel paste deposition process was developed to widen the range of possible materials and applications. This experimental process developed an increasingly complex series of additive manufacturing machines, resulting in new combinations of novel materials and deposition paths without sacrificing many of the design freedoms inherit in the craft process. The investigation made use of open-source software together with an approach to programming user originated infill geometries to form structural parts, differing from the somewhat automated processing by 'closed' commercial RP systems. A series of experimental trials were conducted to test a range of candidate materials and machines which might be suitable for the PDM process. The combination of process and materials were trailed and validated using a series of themed case studies including medical, food industry and jewellery. Some of the object created great interest and even, in the case of the jewellery items, won awards. Further evidence of the commercial validity was evidenced through a collaborative partnership resulting in the development of a commercial version of the experimental system called Newton3D. A number of exciting potential future directions having been opened up by this project including silicone fabrics, bio material deposition and inclusive software development for user originated infills and structures.

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016 / The Precious Metals Industry in South Africa is highly-regulated compared with other mining and trading countries in the western world which have either deregulated their precious metals industries, have only partial controls or have never seen the need to regulate gold and platinum-group metals specifically. South Africa has a specific Act of parliament, the Precious Metals Act, 2005 (a modification of Chapter 16 of the Mining Rights Act, 1967), that regulates possession, trading and manufacture of precious metals. Apart from the Russian Federation, no other country in the world regulates gold and platinum-group metals possession, trading and fabrication to the extent still done in South Africa. The requirement for such stringent controls was based on the country’s pre-eminence in the production of gold and platinum over the past fifty years, exchange controls (in the case of gold) and the contribution of gold and platinum-group metals to foreign exchange earnings and to the country’s economy as a whole. However, much has changed in South Africa, in the world and indeed in the precious metals industries domestically and globally and this work is the first attempt to discuss and analyse developments and proposals that are impacting on the regulation of the precious metals industries in South Africa. Of these, the World Gold Council’s Conflict-Free Gold Standard provides a case for industry self- regulation to complement, or substitute for government regulation in future. The hypothesis at the Proposal Stage of this study was that the precious metals industry in South Africa is over-regulated and should be deregulated. In this study, this hypothesis is explored and debated. The Resource Nationalism -motivated proposals, including Producer-Country Price for Platinum, OPEC-type trade bloc for platinum, precious metal exchange and single-channel marketing of platinum, were analysed in this study. It was concluded that these are wanting in terms of cost/benefit or problematic in terms of international agreements and trade and competition laws. iii The Precious Metals Act, 2005 itself was also critically analysed with a view to evaluating what could be regulated better or deregulated in the light of recent developments and proposals. It was found, ironically, that the old problem of illegal mining and trading needs to be brought under control before deregulation of the precious metals industry can begin. Nevertheless, in the run-up to deregulation (in an estimated 10 to 15 years), industry self-regulation, co-regulation (with industry) hallmarking, and a re-examination of how beneficiation is promoted should be considered.