Browsing by Subject "Copper"
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Item Assembly of colloidal nanocrystals into phospholipid structures and photothermal materials(2012-08) Rasch, Michael; Korgel, Brian Allan, 1969-There has been growing interest in developing colloidal metal and semiconductor nanocrystals as biomedical imaging contrast agents and therapeutics, since light excitation can cause the nanocrystals to fluoresce or heat up. Recent advances in synthetic chemistry produced fluorescent 2-4 nm diameter silicon and 1-2 nm diaemeter CuInSSe nanocrystals, as well as 16 nm diameter copper selenide (Cu₂₋[subscript x]Se) nanocrystals exhibiting strong absorbance of near infrared light suitable for biomedical applications. However, the syntheses yield nanocrystals that are stabilized by an adsorbed layer of hydrocarbons, making the nanocrystals hydrophobic and non-dispersible in aqueous solution. Encapsulating these nanocrystals in amphiphilic polymer micelles enables the nanocrystals to disperse in water. Subsequently, the Si nanocrystals were injected into tissue to demonstrate fluorescence imaging, the photothermal transduction efficiency of copper selenide nanocrystals was characterized in water, and the copper selenide nanocrystals were used enhance the photothermal destruction of cancer cells in vitro. The polymer-encapsulated copper selenide nanocrystals were found to have higher photothermal transduction efficiency than 140 nm diameter Au nanoshells, which have been widely investigated for photothermal therapy. Combining the optical properties of metal and semiconductor nanocrystals with the drug-carrying capability of lipid vesicles has received attention lately since it may create a nanomaterial capable of performing simultaneous drug delivery, optical contrast enhancement, and photo-induced therapy. Hydrophobic, dodecanethiol-coated Au nanocrystals were dispersed in water with phosphatidylcholine lipids and characterized using cryo transmission electron microscopy. 1.8 nm diameter Au nanocrystals completely load the bilayer of unsaturated lipid vesicles when the vesicles contain residual chloroform, and without chloroform the nanocrystals do not incorporate into the vesicle bilayer. 1.8 nm Au nanocrystals dispersed in water with saturated lipids to form lipid-coated nanocrystal agglomerates, which sometimes adhered to vesicles, and the shape of the agglomerates varied from linear nanocrystal chains, to flat sheets, to spherical clusters as the lipid fatty acid length was increased from 12 to 18 carbons. Including squalene formed lipid-stabilized emulsion droplets which were fully loaded with the Au nanocrystals. Results with 4.1 nm Au and 2-3 nm diameter Si nanocrystals were similar, but these nanocrystals could not completely load the bilayers of unsaturated lipids.Item Carbonatites(2009-07) Barker, Daniel S.Item Chemical vapor deposition graphene on polycrystalline copper foil(2014-05) Magnuson, Carl William; Akinwande, Deji; Ruoff, Rodney S.Graphene, a single atomic layer of sp²-bonded carbon, has been of significant interest to basic sciences and engineering. Among its unique properties are exceptional mechanical strength, from the strong carbon-carbon bond; high in-plane thermal conductivity; high carrier mobilities, since electrons and holes travel through graphene as mass-less Dirac fermions; and quantum effects (such as the quantum Hall effect), which can be observed at room temperature. In 2009, Li et al., of Professor Ruoff's research group at the University of Texas at Austin, published a seminal paper detailing the production of fairly high quality graphene grown on copper foils using chemical vapor deposition (CVD). The potential for scalability of graphene CVD processing is extremely attractive, and this is currently the most promising method for its commercial viability, particularly for transparent conductive electrodes (TCEs). Here, graphene-based TCEs are compared with TCEs made with multi-walled carbon nanotubes (MWCNTs). A novel technique to reduce the sheet resistance of MWCNT-based TCEs in half is described in detail. Even with these improvements, graphene-based TCEs outperform MWCNT-based TCEs. The decomposition of copper oxides at high temperatures in an oxygen deficient environment is characterized. The ability for the oxygen evolved from the copper foil during this decomposition to react with carbon on the surface of the copper substrate is verified. This phenomenon was used to develop a technique for getting clean pre-graphene growth copper substrates and allowing repeatable graphene nucleation results. A technique for growing large graphene domains inside a copper vapor trapping 'copper enclosure' is described. The quality of the graphene grown inside the copper enclosure is characterized and shown to be of very high quality. This technique can grow graphene domains over 0.5 mm across. Finally, a possible cause of graphene ad-layer growth on the copper surface is suggested. It is proposed that gas diffusing through the copper substrate at high temperature delaminates the graphene from the copper surface in some regions. This then allows carbon containing molecules to diffuse under the graphene and grow new graphene layers. The increased ad-layer growth in the presence of helium supports this.Item Correlating Cu-Fe sulfides and Au mineralization in the Ertsberg-Grasberg District of Papua, Indonesia using volumetric analysis and trace element geochemistry(2017-08-09) Wright, Kylie Anne; Kyle, J. Richard; Ketcham, Richard Alan, 1965-The Ertsberg-Grasberg District in Papua, Indonesia, hosts two of the world’s largest intrusion-related Cu-Au deposits: the Ertsberg Intrusive System, a hybrid porphyry-skarn deposit, and the Grasberg Igneous Complex, a high-grade porphyry deposit. Cu mineralization within the Grasberg porphyry and Ertsberg skarn systems consists primarily of bornite and chalcopyrite, whereas native gold occurs as inclusions within, or along boundaries of these minerals. Experimental studies by other researchers have shown that at hydrothermal ore-forming temperatures (~300-700°C) and elevated sulfur activity, bornite and chalcopyrite can host 1000s ppm Au within the sulfide lattice or as nano-inclusions. Upon retrograde cooling of the hydrothermal system, the capacity of the Cu-Fe sulfides to host Au significantly decreases to ~10 ppm, suggesting that the Au becomes unstable within the Cu-Fe sulfide matrix and may passively migrate out of the sulfides and coalesce to form native gold grains. These data suggest that Cu-Fe sulfides could exert a strong control on the gold contents of porphyry deposits. However, the traditional model for native gold deposition in large hydrothermal systems relies primarily on fluid pulses, and does not consider gold contributions from the exsolution of previously precipitated gold within Cu-Fe sulfides. To assess the role of Au-bearing Cu-Fe sulfides in the concentration of native gold in this setting, High Resolution X-ray Computed Tomography was used to measure the native gold grains’ shapes, textures, and occurrence modes, and map the extent of contiguous Cu-sulfides. HRXCT data were used to 3D modified Voronoi regions within the Cu-sulfides, as an estimate of diffusional domains that may have provided gold to the Au-grains during cooling. The modified Voronoi volumes are defined for each Au-grain as the set of points within the Cu-sulfide network that are closer to that Au-grain than any other, when measured along a path through the Cu-sulfide. HRXCT data for 11 Ertsberg-Grasberg District ore samples were processed with two different threshold criteria, which produced 16 linear correlation values between modified Voronoi volumes and gold grain volumes. Of these 16 correlation coefficients, none show statistically significant correlations. Because of the paucity of gold grains within our samples, calculated drainage regions commonly extended to the physical edge of the core samples, rendering their actual volumes ambiguous and the correlations associated with them un-interpretable. In cases where numerous gold grains were identified, correlation values were not statistically significant. In general, however, this analysis was impaired by the necessity of interpreting whether all grains in a sample were created by a single event and mechanism. Complementary Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to assess and compare trace element variation within the Cu-Fe sulfides in the district and to constrain spatial variation of Au within Cu-Fe sulfides that contain native gold grains. LA-ICP-MS data show a strong positive correlation between Bi and Ag, and a moderate, positive correlation between Bi and Au, throughout the data. Au occurrences are scattered rather than uniform, where Au concentrations appear in patches throughout the sulfides. This may imply that the majority of non-visible gold exists in Au nanoparticles, rather than solid solution with the Cu-Fe sulfides. Spot analyses and 2D maps indicate the presence of an “enrichment halo” of elevated Au contents in Cu-Fe sulfides surrounding the gold grains. This “enrichment halo” can be interpreted as evidence in support of a hybrid Ostwald-type ripening process that coarsens gold inclusions in chalcopyrite at high-temperatures in porphyry-skarn systems.Item Cysteine responsive copper(II) based ¹⁹F MRI probes(2018-01-26) Enriquez, José Santiago; Que, EmilyCysteine plays an important role upholding cellular homeostasis by maintaining a proper redox environment. Perturbations in cysteine concentration may lead to cardiovascular and liver disease, and cancer, making cysteine an important amino acid to detect and monitor. In order to detect cysteine in vitro and in vivo it is advantageous to choose an imaging tool with high tissue penetration, low background noise, and less radiation, which led us to ¹⁹F MRI. Herein we report a series of copper complexes with fluorine moieties appended to the macrocycle cyclam for use of ¹⁹F MRI detection of cysteine. In this study, an efficient “turn-on” response was observed upon reduction of the Cu(II) complexes by cysteine. This response was characterized using UV/Vis absorption spectroscopy, NMR, EPR, and ¹⁹F MRI. Early biological results suggest that these probes can detect cysteine in red blood cells, opening the doors for further animal studies.Item Deposition and properties of Co- and Ru-based ultra-thin films(2009-12) Henderson, Lucas Benjamin; Ekerdt, John G.Future copper interconnect systems will require replacement of the materials that currently comprise both the liner layer(s) and the capping layer. Ruthenium has previously been considered as a material that could function as a single material liner, however its poor ability to prevent copper diffusion makes it incompatible with liner requirements. A recently described chemical vapor deposition route to amorphous ruthenium-phosphorus alloy films could correct this problem by eliminating the grain boundaries found in pure ruthenium films. Bias-temperature stressing of capacitor structures using 5 nm ruthenium-phosphorus film as a barrier to copper diffusion and analysis of the times-to-failure at accelerated temperature and field conditions implies that ruthenium-phosphorus performs acceptably as a diffusion barrier for temperatures above 165 °C. The future problems associated with the copper capping layer are primarily due to the poor adhesion between copper and the current Si-based capping layers. Cobalt, which adheres well to copper, has been widely proposed to replace the Si-based materials, but its ability to prevent copper diffusion must be improved if it is to be successfully implemented in the interconnect. Using a dual-source chemistry of dicobaltoctacarbonyl and trimethylphosphine at temperatures from 250-350 °C, amorphous cobalt-phosphorus can be deposited by chemical vapor deposition. The films contain elemental cobalt and phosphorus, plus some carbon impurity, which is incorporated in the film as both graphitic and carbidic (bonded to cobalt) carbon. When deposited on copper, the adhesion between the two materials remains strong despite the presence of phosphorus and carbon at the interface, but the selectivity for growth on copper compared to silicon dioxide is poor and must be improved prior to consideration for application in interconnect systems. A single molecule precursor containing both cobalt and phosphorus atoms, tetrakis(trimethylphosphine)cobalt(0), yields cobalt-phosphorus films without any co-reactant. However, the molecule does not contain sufficient amounts of amorphizing agents to fully eliminate grain boundaries, and the resulting film is nanocrystalline.Item Design and synthesis of ligands for luminescent metal complexes(2019-08-30) Davis, Tyler Ian; Jones, Richard A., 1954-Luminescent metal complexes have been extensively investigated for a wide range of applications, including biological imaging and organic light emitting diodes (OLEDs). The ligand 2,6-bispyrazolepyridine (bppy) has shown itself to be an extremely effective sensitizer for Eu³⁺ complexes. Derivatives of this ligand have been synthesized with various oxygen containing groups attached at the 4 position of the pyrazoles. A novel diphosphine containing ligand with a terthiophene backbone has been synthesized. It is believed that this ligand could be used in Cu¹⁺ complexes to create electropolymers capable of thermally activated delayed fluorescence (TADF).Item Fluid inclusion constraints on the hydrothermal processes responsible for Cu-Au mineralization in the Ertsberg East Skarn System, Papua, Indonesia(2017-05-05) Ledvina, Matthew Daniel; Kyle, J. RichardThe Ertsberg East Skarn System (EESS) is a 3-Gt orebody at 0.59% Cu and 0.49 ppm Au that extends from the surface at 4200m at least to 1800m elevation. Skarn-hosted Cu-Au ores are localized in Upper Cretaceous siliciclastic to Lower Paleogene carbonate strata along the steeply dipping contact with the 3-Ma Ertsberg Diorite that locally hosts stockwork ores. Petrography, quartz SEM-Cathodoluminesence (SEM-CL), fluid inclusion microthermometry, and fluid inclusion LA-ICP-MS were used to characterize vein formation and fluid conditions in the ore-forming system. Five vein-hosting lithologies and five stages of vein formation were defined petrographically, and 41 SEM-CL transects from 17 quartz vein samples were used to identify eight recurring quartz CL textures that vary by elevation and host lithology. The CL texture paragenesis reveals quartz-sulfide vein architecture rife with brittle deformation features and evidence of repeated opening and mineralization of fractures. Brittle deformation increased with depth in diorite-hosted veins and was most prevalent in skarn-hosted veins. Fluid inclusion petrography of 16 samples, in-situ micro-thermometry of 107 fluid inclusions in eight samples, and LA-ICP-MS of 99 inclusions revealed four types of inclusions consistent with Cu-Au porphyry systems. Type 1 inclusions are 4-11% salinity, 40-70 vol% vapor bubble, homogenize between 332-396 C and can contain chalcopyrite daughter crystals. Type 2a inclusions are 27-51% salinity, 10-30 vol% vapor bubble, homogenize between 280-420 C and contain halite. Type 2a inclusions may also contain sylvite, anhydrite, chalcopyrite, magnetite, and hematite. Type 2b inclusions are 1-12% salinity, 65-90 vol% vapor bubble, homogenize between 340-392 C and typically do not contain daughter minerals. Type 3 inclusions at ambient conditions are 2-23% salinity, 15-50 vol% vapor bubble, homogenize between 283-403C and may contain opaque minerals. LA-ICP-MS analysis indicate that EESS fluid inclusions have high Na, K, and Ca, and support mineralization by Cu, Fe, Mn, Pb and Zn-rich brine derived from phase separation of a primary magmatic fluid. All fluid inclusion types were observed over the 1.7 km of elevation sampled – nearly 4x the vertical extent documented for other porphyry systems. The upper limit of the phase separation zone is present at ~2500 m, which corresponds with deepest known Cu-Au concentrations. These data support fault-controlled fluid migration and a lack of lithologic control on Cu-Au mineralization in veins.Item Growth, structure, and chemistry of 1B metal nanoclusters supported on TiO₂(110)(2006) Pillay, Devina; Hwang, Gyeong S.Cu, Ag, and Au nanoclusters dispersed on TiO2(110) surfaces are utilized in a wide variety of applications ranging from microelectronics to heterogeneous catalysis. The unique chemical reactivity of these clusters is largely dependent on their size, shape, spatial distribution, and interfacial interaction with the oxide support. This implies that atomic level control of these properties can offer great opportunities in the development of novel devices based on supported metal nanoclusters. It is therefore necessary to understand how formation and restructuring of these clusters alter their geometric and electronic characteristics. This thesis involves the development of a theoretical foundation for studying the growth, structure, and chemistry of Cu, Ag, and Au on TiO2(110) surfaces. Using density functional theory calculations, we have identified factors that control the chemical reactivity of these supported metal nanoclusters. First we investigated the electronic and geometric structures of the stoichiometric and reduced rutile TiO2(110) surfaces. Then we examined the surface chemistry of TiO2 towards gaseous CO and O2, as well as the structure and growth of 1B metal nanoclusters on TiO2(110). We also examined how the electronic and geometric properties of mixed metal nanoclusters, CuAun(n≤ 3), differ versus their single metal counterparts, Cum and Aum (m ≤ 4). Finally, we considered CO oxidation reactions on TiO2(110)-supported small Au clusters. While current experimental techniques are limited to providing complementary atomic-level real space information, first principles-based atomic level simulations greatly contribute to elucidating the fundamental behavior and properties of Cu, Ag, and Au nanoclusters on TiO2(110). First principles modeling has paved the way for new catalyst development by investigating how the geometric, electronic, and chemical properties of TiO2-supported 1B metal nanoclusters vary with surface defects, adsorbates, and metal dopants before valuable time and manpower is invested in experimental synthesis and characterization.Item Indirect Evolution of Hybrid Lethality Due to Linkage with Selected Locus in Mimulus guttatus(Public Library of Science, 2013-02-26) Wright, Kevin M.; Lloyd, Deborah; Lowry, David B.; Macnair, Mark R.; Willis, John H.Most species are superbly and intricately adapted to the environments in which they live. Adaptive evolution by natural selection is the primary force shaping biological diversity. Differences between closely related species in ecologically selected characters such as habitat preference, reproductive timing, courtship behavior, or pollinator attraction may prevent interbreeding in nature, causing reproductive isolation. But does ecological adaptation cause reproductive incompatibilities such as hybrid sterility or lethality? Although several genes causing hybrid incompatibilities have been identified, there is intense debate over whether the genes that contribute to ecological adaptations also cause hybrid incompatibilities. Thirty years ago, a genetic study of local adaptation to copper mine soils in the wildflower Mimulus guttatus identified a locus that appeared to cause copper tolerance and hybrid lethality in crosses to other populations. But do copper tolerance and hybrid lethality have the same molecular genetic basis? Here we show, using high-resolution genome mapping, that copper tolerance and hybrid lethality are not caused by the same gene but are in fact separately controlled by two tightly linked loci. We further show that selection on the copper tolerance locus indirectly caused the hybrid incompatibility allele to go to high frequency in the copper mine population because of hitchhiking. Our results provide a new twist on Darwin's original supposition that hybrid incompatibilities evolve as an incidental by-product of ordinary adaptation to the environment.Item Methods for modifying the physical and catalytic properties of surfaces(2010-05) Flaherty, David William, 1980-; Mullins, C. B.; Henkelman, Graeme; Hwang, Gyeong S.; Korgel, Brian A.; Sitz, Greg O.Catalysts can be significantly improved by modifying their structure or composition. Simple adaptations of the physical structure of a catalyst can give rise to changes in the chemical behavior, in part, due to alterations in the coordination of active sites. Modifications in the surface or bulk composition of a material have a profound impact on the chemistry that is promoted as a result of electronic and physical factors. Optimizing these qualities may enhance the catalyst’s activity, selectivity or stability. In this dissertation, we explore the application of two distinct approaches for modifying the chemical properties of catalytically active materials. Through the use of a broad array of techniques we quantify changes in critical properties such as physical-crystallographic structure; morphology, surface area and porosity; as well as catalytic activity, selectivity and stability. First, reactive ballistic deposition of metal atoms within a low pressure gas provides a unique opportunity for synthesizing thin films of a wide variety of materials. The morphology, structure, and porosity of the resulting material can be tailored through control of the deposition angle and substrate temperature. By conducting deposition perpendicular to the surface, a film can be grown with a dense, conformal structure. On the other hand, deposition at oblique angles results in high surface area, porous films comprised of regular arrays of nanocolumnar structures. Furthermore, variations in the deposition angle allow for the inclusion of under-coordinated sites which change the chemical activity of the surface. Improvements in the activity, selectivity and stability of transition metal catalysts can be made by alloying the catalyst with a second element. The formation of molybdenum carbide decreases the strength of chemisorption on the surface, with respect to molybdenum, and improves selectivity for the dehydrogenation of formic acid. Platinum is active for the water-gas shift reaction. However, this catalyst cannot operate at low temperatures due to CO poisoning and is susceptible to deactivation due to accumulation of carbonaceous deposits. The formation of a platinum-copper near-surface alloy dramatically modifies the interactions of the surface with CO, H₂O and H₂ which can enhance the performance of this catalyst for the water-gas shift reaction.Item Miners and musicians : rethinking company towns through the Butte Mines Band, 1887-1953(2020-12-10) Lockman, Gwendolyn Reid; Bsumek, Erika MarieThis masters’ report argues that the role of the Butte Mines Band in its community, from funerals to celebrations of life for miners and their families, shows how life in Butte, Montana outside of mining was mediated by copper mining interests, but that the city was not a company town. This is primarily evident from financial support of the Band by Butte’s copper companies, but it is also part of a more complex story of corporate influence, unionism, and environment. Using a socio-environmental lens to look at how environment and human interaction work in concert to create social and cultural structures, norms, and behaviors, this study reconsiders the meaning of the phrase “company town,” and considers a scope of “studyscapes” to analyze sensory knowledge of Butte. These include landscape, workscape, soundscape, playscape, and deathscape. The Mines Band offers a confluence of these culturescapes that reveals a complicated web of influence on local culture. This report primarily uses archival research from the Butte-Silver Bow Public Archives in Butte, Montana. It builds on the historiography of mining, labor, recreation, unionism, and environment in the U.S. West. It also uses interdisciplinary methods by borrowing from ethnographic social sciences to consider walking as valuable historical method for place-based study. This is done in concert with studying sensory history. While historical sound and smell cannot be determined by present qualitative evaluations, the historian can revisit place to better consider the context for how sensory consumption may have changed over time. Chapter One details the extant scholarship on Butte and introduces readers to the theoretical frameworks for studying the Mines Band in a socio-environmental context. It outlines the problems with considering Butte a company town while offering a means to understand the complex corporate-cultural relationship in the city. Chapter Two focuses on Butte’s urban development and cultural makeup, outlining the several sensory landscapes of life in Butte, including soundscape, smellscape, playscape, and deathscape. Chapter Three details homes in on the Butte Mines Band and examines its role in the city, connecting place, mining, and death to cultural customs.Item N-alkynylations of substituted pyrroles with 1-bromo-1-alkynes and C-alkylations and C-alkenylations of cyclic 1,2-diketones(2019-05-10) Reinus, Brandon Joseph; Martin, Stephen F.; Kerwin, Sean M.; Anslyn, Eric; Brodbelt, Jennifer; Liu, Hung-Wen; Dong, GuangbinNitrogen-substituted alkynes are a unique class of compounds that have found general use in organic synthesis. The catalytic synthesis of N-substituted alkynes offers a rapid and step-efficient approach for accessing this structural motif. To better understand the synthesis and reactivity profile of N-alkynyl pyrroles, a study of the Cu-catalyzed coupling of pyrroles with 1-bromoalkynes was conducted and the scope uncovered. Subsequently, N-alkynyl pyrroles were applied to the synthesis of pyrrole[2,1-c]oxazin-1-ones and the formal total synthesis of the natural product peramine. Additionally, an N-alkynyl pyrrole was applied toward the synthesis of the pyrrole spiroketal alkaloid shensongine A. The α-alkylation of ketones is an indispensible C-C bond forming process to organic chemists. This process generally involves the formation of an enolate and subsequent alkylation with an electrophile. While very efficient, this series of steps generates a significant amount of waste that is often not on the radar of the typical chemist. Recent work has begun to address this issue resulting in several new “green” α-alkylation procedures. In an effort to better understand the potential application of a C-H activation procedure towards the “green” alkylation of ketones a study of the C-H activation and subsequent alkylation and alkenylation of cyclic 1,2-diketones was conducted.Item The paradox of renter's insurance : resource stabilization funds in Venezuela and Chile(2010-12) Johnson, Matthew Alan; Madrid, Raúl L.; Weyland, KurtThis report, rooted in the conflict over the control of natural resource wealth, departs from the widely-accepted findings of two disparate literatures. First, while recent analyses correctly conclude that natural resources rents play a contingent role in development, this study deviates from the conventional wisdom attributing the variation of the resource curse to formal institutions. Secondly, as opposed to the recent wave of “political insurance” arguments that ascribe the creation of reforms to weak incumbents attempting to tie the hands of their successors, I argue that actors pursue similar institutional reforms for economic and political reasons. I build on these literatures by examining the commitment to a specific government institution—stabilization funds, which manage the fluctuations of natural resource rents and stop natural resource wealth from being a curse—across three natural resource-rich Latin American countries: Chile, Mexico and Venezuela. Paradoxically, because successful stabilization funds provide greater political benefits when rents are saved, I argue that these institutions only tie the hands of political successors from using rents for political purposes when they are created for economic purposes.Item The political logic of renter’s insurance : the resource curse, institutions, and the foundations of institutional strength in Latin America(2012-08) Johnson, Matthew Alan; Weyland, Kurt Gerhard; Madrid, Raúl L.; Hunter, Wendy; McDonald, Patrick; Greene, KennethWhat effects do natural resources, and more specifically the revenues from the extraction and sales of commodities, have on the economies of well-endowed countries in Latin America? How does the political administration of natural resource wealth affect the economic trajectories of these developing countries? Under what conditions do countries successfully use political institutions to administer natural resource windfalls prudently? My dissertation addresses these questions and ultimately explains why natural resource wealth is a blessing for the development of some countries and a curse for others. Specifically, I examine the effectiveness of specific government institutions—called Nonrenewable Resource Stabilization Funds (NRSFs or stabilization funds), which help countries to manage the economic challenges associated with relying upon volatile natural resource revenues—in Chile and Venezuela, two natural resource-rich Latin American countries. Although both of these countries created a NRSF, Chile’s has been very successful while Venezuela’s was extremely weak from the outset. My research suggests that the degree of stabilization fund success—which impacts the severity of the resource curse—depends on these institutions constraining political actors from using rents for venal purposes. In turn, I find that the capacity of NRSFs to restrain the passions of self-interested executives is largely a product of the circumstances accompanying the creation of these institutions; that is, the conditions into which these institutions are born impact stabilization fund performance, but not in the way that the traditional literature predicts. In contrast to extant explanations suggesting that NRSF success is dependent upon clear institutional rules or general state capacity, I find that stabilization funds tend to be unsuccessful when political needs drove their creation while these institutions are likely to function well when economic concerns were the impetus for their adoption. I substantiate the case study evidence of Chile and Venezuela with a broad statistical analysis of 20 other countries that have created NRSFs.Item A protocol to evaluate the adsorptive removal of dissolved copper and zinc from highway runoff(2014-05) Ernst, Clayton Owen; Katz, Lynn EllenThe increasing urbanization of landscapes significantly alters the surface water hydrology of impacted watersheds. As a side effect, stormwater discharges to receiving water bodies are often of decreased quality due to pollutants deposited on impervious urban surfaces being entrained by runoff. A pertinent example of this problem is the presence of copper and zinc in highway runoff. Both copper and zinc have been shown to exert toxic effects on aquatic micro- and macro-biota. Copper in particular has been shown to harmfully disrupt the olfactory nervous system of fish species at concentrations as low as 3 [mu]g/L. To meet these limits, treatment of highway runoff for the removal of copper and zinc is necessary. However, due to the complexities associated with the behavior of heavy metals in natural systems, the appropriateness of removal techniques will necessarily depend on a variety of system-specific factors and chemical characteristics of highway runoff. Adsorption has been shown to be generally effective in the removal of dissolved heavy metals, but the choice of adsorptive media is again dependent on system-specific parameters. This study developed and evaluated a column testing protocol that can be used to quickly and reliably evaluate adsorptive removal of dissolved heavy metals from highway runoff. The protocol is demonstrated in an evaluation of iron oxide, manganese oxide, crab shell, concrete, and bone meal media for removing dissolved copper and zinc from highway runoff. The performance of these media was assessed as a function of various runoff characteristics including pH, ionic strength, alkalinity, and total organic carbon. The methodology was used to show that iron oxide media in combination with crab shell or concrete media provided the most effective removal of copper and zinc from highway runoff. Through this study, the convenience, flexibility, and robustness of the proposed protocol are compellingly established.Item Quantum state resolved studies of copper-H₂ system and electronic spectroscopy of Cu(100)(2009-08) Uka, Arban; Sitz, Greg OrmanHydrogen quantum state resolved energy losses upon scattering from copper are studied using molecular beam techniques and quantum state-specific detection methods. Also clean copper and hydrogen and oxygen covered copper surfaces were studied using electron spectroscopy. There are many questions about the nature of molecule-surface dynamics and the processes. The relative role of the different degrees of freedom in the reaction and the importance of non-adiabatic effects have been two of these questions. These two questions motivated this work. Energy loss in the elastic scattering of H₂(v=1. J=1) and H₂(v=0, J=1) molecular quantum states is measured as a function of incident translational energy at two surface temperatures. The energy loss process is shown to agree to the Baule classical model for energy ranges 74-150 meV for the excited vibrationally state and 74-125 for the ground vibrational state. Results suggest that translational energy is more effective that vibrational energy in the observed process. Theoretical models have been able to explain several processes using nonadiabatic models where friction coefficient tensor is included. Results in this thesis suggest that the energy loss in the elastic scattering is a nonadiabatic one. Electron spectroscopy studies showed that the surface plasmon intensity is very sensitive to surface contamination. Using this property, surface-only sensitive virtual temperature programmed desorption (VTPD) is developed. A better understanding of unique behavior of hydrogen covered Cu(100) was gained.Item Statue of Liberty(0000-00-00) Landsman, RobertAudio files are EID restricted. Individuals without an EID should send an email request to apl-aaa@lib.utexas.edu.Item Surface chemistry considerations for enhanced vapor deposition of metals(2014-05) Elko-Hansen, Tyler Don-Michel; Ekerdt, John G.Electrolessly deposited CoWP capping layers have been demonstrated to effectively reduce electromigration of Cu at the interconnect/dielectric-barrier cap interface while reducing resistivity relative to SiCN. However, as device dimensions scale, the need for alternative methods for the selective deposition of sub-5 nm, ultrathin, conformal Co capping layers is apparent. To develop methods for area-selective atomic layer deposition (AS-ALD) of Co caps for next-generation Cu interconnects, the ALD behavior of bis(N-tert-butyl-N’-ethylpropionamidinato) cobalt(II) (CoAMD) is evaluated on Cu, SiO₂, and a porous low-k ( ~2.6) dielectric, CDO. The first and second ALD half reactions of CoAMD on the respective substrates is evaluated with H₂ coreactant by adsorbing the precursor on the substrates under ALD cycling conditions at 265 °C with and without coreactant exposure. The adsorption studies indicate that CoAMD preferentially deposits most on Cu and least on CDO. Further, CoAMD, like other amidinate precursors, readily dissociates on the Cu transition metal surface but the ultimate per-cycle coverage is self-limited by the slow desorption of amidinate ligands and fragments from the Cu surface. Co films deposited by ALD from CoAMD on Cu at 265 °C indicate that Co burrows into the lower energy Cu surface as the film grows in order to reduce the free surface energy. The Cu remains as a surfactant-like layer on the topmost Co surface up to film thicknesses of at least 16 nm. Moreover, considerable intermixing at the Co/Cu interface and Cu concentration several nm into the Co films are observed indicating high surface mobility of the two materials and Cu diffusion at polycrystalline Co grain boundaries. Finally, employing low-tempurature ALD and selectively passivating the dielectric surfaces with OH targeting passivants leads to enhanced selectivity of CoAMD for deposition on Cu versus SiO₂ and CDO. Depositing Co from CoAMD on Cu and CDO at 165 °C after 500 kTorr-s exposure to trimethylchlorosilane at 50 °C leads to a 30:1 preference for Co accumulation on Cu, a twelve times improvement compared to deposition on cleaned Cu and CDO at 265 °C.Item The functional role of the copper transporter 1 in spermatogenesis and in cisplatin-induced testicular injury(2019-05) Ghaffari, Rashin; Mukhopadhyay, Somshuvra; Richburg, John H.; Vokes, Steven A; Tucker, Haley O; Vasquez, Karen MCisplatin (cis-diamminedichloroplatinum(II) (cDDP)) is a highly effective chemotherapeutic drug used for the treatment of various cancers including ovarian, bladder, cervical, head and neck, small-cell and non-small-cell lung cancer. Unfortunately, cDDP is encumbered by its dose-limiting toxicity including prolonged azoospermia and, in some cases, permanent male infertility. Since patients that undergo cDDP based chemotherapy for these types of cancers are mostly young men in their prime reproductive age (ages 15-44), one of the major concerns after their recovery is infertility which would affect their quality of life. Therefore, it important to understand the mechanism of this reproductive toxicity in order to develop strategies to alleviate cDDP induced testicular injury that results after chemotherapy exposure. It has been well established that cDDP induces apoptosis in tumor and normal cell types, however, mechanisms leading to its long-lasting reproductive toxicity is less understood. Whether cDDP-induced impairment of spermatogenesis is a result of direct drug exposure to the germ cells (GCs) or results from a secondary effect to the somatic Sertoli cells (SCs) function remains unclear. An increasing body of evidence has implicated the major role of the high-affinity copper (Cu) transporter 1 (SLC31A1, CTR1), which functions in the uptake of Cu into mammalian cells, in cDDP sensitivity. The level of Ctr1 expression is recognized to be highly associated with cDDP accumulation and sensitivity in eukaryotic cells. The testis is one of the organs that express high Ctr1 mRNA and protein levels, which suggests that CTR1 protein may play a significant role in cDDP induced toxicity in testis. Moreover, given the essential role of CTR1 in Cu homeostasis, very little is known on the Cu transport mechanism and the physiological role of CTR1 protein in testis. Thus, this dissertation is focused on deciphering the role of CTR1 in testicular Cu homeostasis and its functional role in cDDP-induced testicular injury. In this thesis, two independent mouse models were generated with the conditional knockout of Ctr1 in either GCs (GC [superscript ΔCtr1]) or SCs (SC [superscript ΔCtr1]) using the Cre-Lox system. Loss of Ctr1 in GCs revealed the essential role of its expression in GCs to maintain functional spermatogenesis. GC [superscript ΔCtr1] mice exhibited a significant reduction of testicular mass by a severe progressive loss of GCs starting at postnatal day (PND) 28 leading to testis hypoplasia by adulthood. No spermatogenic recovery was observed in GC [superscript ΔCtr1] testis beyond PND 41, despite the presence of undifferentiated spermatogonial cells. On the other hand, SC [superscript ΔCtr1] mice were indistinguishable from their WT littermates with respect to fertility, spermatogenesis, growth, and development. Upon examination of testicular Cu level, SC [superscript ΔCtr1] mice exhibited significant reduced Cu and Cu-dependent cellular activities. The results from the two independent mouse models reveal, for the first time, the differential cell-specific role of CTR1 expression by testicular cell types (GCs and SCs) in maintaining functional spermatogenesis and Cu homeostasis. Finally, the role of CTR1 expression by SCs in cDDP-induced testicular injury was examined. Due to the testicular hypoplasia of the adult GC [superscript ΔCtr1] mouse testis, cDDP treatment of GC [superscript ΔCtr1] mice was not performed. Acute treatment of cDDP (5mg/kg) on SC [superscript ΔCtr1] mice was done and analyzed. Interestingly, SC [superscript ΔCtr1] mice testis exhibited higher resistance to cDDP-induced GC apoptosis than WT mice. Moreover, cDDP treated SC [superscript ΔCtr1] mice testis displayed significantly less platinum levels than their treated WT littermates. The results in this study provide the first evidence that loss of CTR1 expression by SCs enhances testis resistance to cDDP toxicity by reducing the accumulation of cDDP in testis. Taken together, the observations described within this thesis demonstrate the physiological role of CTR1 for functional spermatogenesis and Cu homeostasis in testis. Furthermore, loss of CTR1 expression in SCs revealed a newly identified pathway for cDDP uptake and toxicity. The mechanism(s) underlying the Cu transport system in testis and its effect on fertility will provide insights into the possible development of targeted therapies to improve fertility in individuals who are affected from diseases connected to an imbalance of Cu metabolism. Furthermore, the involvement of CTR1 in cDDP injury to the SCs sets the foundation to further understand and design strategies to protect or alleviate long-lasting reproductive injury following cDDP therapy