Tesi sul tema "Gold"
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Coetzee, Karolien. "Gold complexes obtained from gold ylide preparations". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/21206.
Testo completoENGLISH ABSTRACT: This investigation comprised the synthesis and characterisation of new Au(I) phosphonium ylide complexes and other compounds formed during coordination reactions. These complexes could exploit the synergism between two pharmacologically active substances (gold complex unit and phosphorus ylide) to furnish an even more active substance. Four phosphonium salts were prepared, [C6H5CH2PPh3]Br (1), [Ph3P(CH2)3PPh3]Br2 (2a), p-[{Ph3PCH2}2C6H4]Br2 (3a) and m- [{Ph3PCH2}2C6H4]Br2 (4a), by reacting PPh3 with the corresponding alkylbromides. The 13C and 1H NMR spectra of the compounds 1 – 4a indicated that many of the nuclei are magnetically inequivalent. The aromatic units in PPh3 are normally identical, but multiple, overlapping signals proved that the corresponding ortho, meta and para carbon and proton nuclei are in magnetically different environments from each other. Single crystal structures of salts 3a and 4a were determined. Different methods were followed to deprotonate the phosphonium salts to afford the corresponding ylides and to coordinate the ylides to gold precursor compounds. Most of the reactions yielded inseparable mixtures of products and pure compounds could not be isolated in large enough quantities for characterisation by all physical methods. Sufficient crystals for structure determination by X-ray diffraction were obtained. The product mixtures were characterised by 1H, 13C and 31P NMR spectroscopy and mass spectrometry. Characteristic downfield chemical shift changes after coordination of the ylides to Au(I) were observed for the carbon and phosphorus nuclei, while the protons displayed upfield shifts. Reaction of (C6F5)Au(tht) with the salts 1 – 4a, and subsequent deprotonation yielded the gold(I) ylide complexes [C6H5CH(AuC6F5)PPh3] (5), [{Ph3PCH(AuC6F5)}2CH2] (6), p-[{Ph3PCH(AuC6F5)}2C6H4] (8), and m- [{Ph3PCH(AuC6F5)}2C6H4] (9). The crystal and molecular structures of compounds 5 and 9 were determined. Deprotonation of 4a with n-BuLi, followed by reaction with (C6F5)Au(tht) yielded complexes 9 and [{Ph3PCH2}2C6H4][BrAuC6F5]2 (10). The crystal structure of compound 10 was determined. Two aurocyclic compounds, [μ- {(Ph3PCH)2CH2}2Au2][BF4]2 (12) and [μ–{(Ph3PCH)2C6H4}2Au2][BF4]2 (13) were synthesised by deprotonating salts 2b and 3b with n-BuLi and subsequently reacting the corresponding bisylides with ClAu(tht). Reaction procedures in which Ag2O was used as deprotonating agent for the phosphonium salts 2a, 3a and 4a, yielded mixtures of products. Single crystals of complexes m-[Ph3PCH(AuC6F5)C6H4CH3] (14), [C6F5Au(tht)] (15) and [(C6F5)2Au][(Ph3PCH2)2C6H4] (16) were isolated from the reaction mixtures and subjected to X-ray crystal structure determination. The molecular structure of 15 exhibited unusual aurophilic interactions and represents the first example of a linear gold chain in which the gold···gold distances systematically alternate between 3.13Å, 3.31Å and 3.20Å. Salt 2b was reacted with Ph3PAu(acac) to afford the desired compound, [{Ph3PCH(AuPPh3)}2CH2](BF4)2 (19), along with [CH3C(O)C(AuPPh3)2C(O)CH3] (17) and some byproducts. Compound 17 was characterised by single crystal Xray diffraction. The fluorobiphenylgold(I) complexes, 4,4’-[(AuPPh3)2C12F8] (21) and 2,2’- [(AuPPh3)2C12F8] (22) were synthesised by reaction of ClAuPPh3 with the lithiated 2,2’-dibromooctafluorobiphenyl and 4,4’-dibromooctafluorobiphenyl respectively. The molecular structure of 21 revealed that one of the C–Au–P bond angles deviates from linearity by 12.5°, probably as a result of π-stacking of the tetrafluorophenyl rings and steric requirements of the bulky PPh3 units. The other C–Au–P bond angle is linear [177.9(3)°].
AFRIKAANSE OPSOMMING: Hierdie studie behels die sintese en karakterisering van nuwe fosfoniumylied goud(I)-komplekse en ander verbindings wat gedurende koördinasiereaksies vorm. Sulke komplekse kan sinergisme tussen twee farmakologies-aktiewe entiteite (goud(I) en fosfoniumylied) om ʼn meer aktiewe verbinding te vorm meebring. Vier fosfoniumsoute is berei, [C6H5CH2PPh3]Br (1), [Ph3P(CH2)3PPh3]Br2 (2a), p- [{Ph3PCH2}2C6H4]Br2 (3a) en m-[{Ph3PCH2}2C6H4]Br2 (4a), deur PPh3 met die ooreenstemmende alkielbromiedes te reageer. Die 13C- en 1H- KMR-spektra van dié verbindings toon dat ʼn aantal kerne in aromatiese ringe magneties onekwivalent is. Normaalweg is die koolstowwe in PPh3-eenhede ekwivalent, maar meervoudige, oorvleuelende pieke het nou getoon dat die ooreenstemmende orto-, meta- en para-koolstof sowel as die ooreenstemmende protonkerne in verskillende magnetiese omgewings voorkom. Die kristalstrukture van die soute 3a en 4a hierbo is met behulp van X-straal tegnieke bepaal. Verskillende metodes is gevolg om die fosfoniumsoute te deprotoneer na die ooreenstemmende yliede en om die yliede dan aan goud-bevattende uitgangstowwe te probeer koördineer. Die meeste reaksies het nie-skeibare mengsels gevorm en enkelprodukte kon nie in groot genoeg konsentrasies geïsoleer word om hulle afsonderlik te karakteriseer nie. Kristalle vir X-straal kristalstruktuur bepalings is verkry. Die produkmengsels is gekarakteriseer met behulp van 1H-, 13C- en 31P- KMR-spektroskopie en massaspektrometrie. Karakteristieke veranderinge in chemiese verskuiwings na laer veldsterktes vir die koolstof en fosfor kerne is waargeneem na koördinasie van die yliede aan Au(I), terwyl die protone na höer veldsterktes verskuif het. Die reaksie tussen (C6F5)Au(tht) (tetrahidrotiofeen) en soute 1 – 4a gevolg deur deprotonering, vorm die goud-yliedkomplekse [C6H5CH(AuC6F5)PPh3] (5), [{Ph3PCH(AuC6F5)}2CH2] (6), p-[{Ph3PCH(AuC6F5)}2C6H4] (8), en m- [{Ph3PCH(AuC6F5)}2C6H4] (9). Die kristalstrukture van komplekse 5 en 9 het al die molekulêre interaksies daarin blootgelê. Deprotonering van 4a met n-BuLi, gevolg deur reaksie met (C6F5)Au(tht) lewer komplekse 9 en [{Ph3PCH2}2C6H4][BrAuC6F5]2 (10). Die kristal- en molekulêre struktuuur van kompleks 10 is bepaal. Twee aurosikliese verbindings, [μ- {(Ph3PCH)2CH2}2Au2][BF4]2 (12) en [μ–{(Ph3PCH)2C6H4}2Au2][BF4]2 (13) is gesintetiseer deur gedeprotoneerde bisyliede verkry van 2b en 3b met substitusie van tht aan die ClAu-eenheid te koördineer. Reaksieprosedures waarin Ag2O vir deprotonering van die fosfoniumsoute 2a, 3a en 4a gebruik is, het tot mengsels van produkte aanleiding gegee. Enkelkristalle van komplekse [Ph3PCH(AuC6F5)C6H4CH3] (14), [C6F5Au(tht)] (15) en [(C6F5)2Au][(Ph3PCH2)2C6H4] (16) is geïsoleer uit die reaksies en kristalstruktuurbepalings is uitgevoer. Die molekulere struktuur van 15 toon ongewone aurofiliese interaksies en verteenwoordig die eerste voorbeeld van ʼn linieêre goudketting; met goud···goud afstande wat sistematies varieër tussen 3.13Å, 3.31Å en 3.20Å. Sout 2b is met Ph3PAu(acac) gereageer om die gewenste produk, [{Ph3PCH(AuPPh3)}2CH2](BF4)2 (19), saam met [CH3C(O)C(AuPPh3)2C(O)CH3] (17) en ander byprodukte te vorm. Verbinding 17 is as enkelkristalle Xstraalkristallografies gekarakteriseer. Die fluorobifeniel goud(I)-komplekse, 4,4’-[(AuPPh3)2C12F8] (21) en 2,2’- [(AuPPh3)2C12F8] (22), is gesintetiseer deur koördinasie van AuPPh3 aan die gelitieërde 2,2’-dibromooktafluorobifeniel en 4,4’-dibromooktafluorobifeniel respektiewelik. Die molekulere struktuur van 21 het getoon dat een van die C-Au- P bindingshoeke met 12.5º afwyk van 180º, waarskynlik as gevolg van π- interaksie van die tetrafluorofenielringe en die steriese vereistes van die groot PPh3-eenhede. Die ander C-Au-P bindingshoek is linieêr [177.9(3)°].
Mulley, Melinda Ann. "We hear nothing but gold, gold, gold : women and poverty in South Australia during the gold rushes 1850-1855 /". Title page, table of contents and introduction only, 2004. http://web4.library.adelaide.edu.au/theses/09AR/09arm9589.pdf.
Testo completoWetzel, Mary S. "Sodek's Gold". Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc500390/.
Testo completoCotten, Nicole. "Fool's gold". Thesis, University of Iowa, 2018. https://ir.uiowa.edu/etd/6086.
Testo completoWarm, Julie J. Day Nancy E. "From good to gold: predicting nonprofit engagement in entrepreneurial activity /". Diss., UMK access, 2004.
Cerca il testo completo"A dissertation in public affairs and administration and education." Advisor: Nancy Day. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 28, 2006. Includes bibliographical references (leaves 107-113). Online version of the print edition.
Gottfried, Jörg Michael. "CO oxidation over gold adsorption and reaction of oxygen, carbon monoxide, and carbon dioxide on an Au(110)-(1x2) surface /". [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/133/index.html.
Testo completoSkelton, Helen Elisabeth. "Gold and gold-based nanoparticles for NOx reduction catalysis". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610182.
Testo completoYang, Yi. "Gold(I) oxo, imido, hydrazido complexes and gold clusters /". free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9841362.
Testo completoBartlett, Samuel Andrew. "God, Gold, or Glory: Norman Piety and the First Crusade". UNF Digital Commons, 2008. http://digitalcommons.unf.edu/etd/119.
Testo completoJennings, Nicola. "Laser deposition of metallic gold using gold(I)-carbene complexes". Thesis, Keele University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436197.
Testo completoGomes, Ricardo Cláudio. "Is gold a hedge? The relation between gold and shares". Master's thesis, Instituto Superior de Economia e Gestão, 2016. http://hdl.handle.net/10400.5/13080.
Testo completoNum período em que uma estratégia de investimento cuidadosa e diligente é cada vez mais necessária, o hedging é uma poderosa ferramenta que pode ser usada pelos investidores com o propósito de reduzir os riscos associados aos investimentos no mercado de ações. Este projecto tem como objectivo estudar a correlação entre os retornos do ouro e os retornos das ações, com o intuito de descobrir se o ouro pode ser considerado um hedge para as ações ou um safe haven. Os resultados do uso de um modelo econométrico, baseado em dados de alguns dos maiores índices a nível mundial e de um índice de rastreamento de referência para futuros de ouro, para o período de Janeiro de 1996 até Dezembro de 2015, sugerem que o ouro não é um hedge para qualquer dos mercados de ações analisados, ainda que aparente ser um forte safe haven sobre condições extremas de retornos negativos do mercado de ações. Ainda assim, é demonstrado que os resultados do modelo econométrico estão dependentes do período analisado.
In a period where careful and diligent investing is increasingly required, hedging is a powerful weapon that can be used by investors in order to reduce the risks associated with stock market investments. This project aims at studying the correlation between gold returns and stock returns, intending to find out if gold can be considered a hedge for stocks or a safe haven. The results of the use of an econometric model, based on data from some major worldwide stock indexes and a benchmark tracking index for gold futures, regarding the period from January of 1996 until December of 2015, suggest that gold is not a hedge for any of the stock markets under analysis but it appears to be a strong safe haven under extreme negative stock market conditions. However, it is shown that the results from the model are dependent on the period analysed.
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Taurasi, Donatella <1984>. "Gold and the Stock Market: 3 Essays on Gold Investments". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5693/1/Taurasi_Donatella_Tesi.pdf.
Testo completoTaurasi, Donatella <1984>. "Gold and the Stock Market: 3 Essays on Gold Investments". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5693/.
Testo completoAhmad, Khurram, e Muhammad Azeem. "Gold Standard Website". Thesis, Växjö University, School of Mathematics and Systems Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-5520.
Testo completo
The aim of this thesis is to design a web base system which provides functionality of comparison between two java files on the basis of point-to information (P2I). User will upload Java files and analysis of Java files called point-to analysis (P2A). System will store the files in the file system for reference and download in later time. System will extract the information called P2I from P2A and it will store that information in the database.
Database should be flexible to accommodate the changes in P2A file and system should be able to extract the P2I and store it in database with minimum support of system administrator.
Smith, Jon Anthony. "Polyaniline Gold Nanocomposites". Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4900.
Testo completoTran, Dung Trung. "Gold-containing bimetallicnanoparticles". Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1362/.
Testo completoBall, Liam Thomas. "Oxidative gold catalysis". Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.649363.
Testo completoDavies, Scott. "Catalysis by gold". Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/100727/.
Testo completoKowalski, Steven Casimer. "Gray and Gold". Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1154351928.
Testo completoAmir, Juliana R. "Glass and Gold". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491472934550759.
Testo completoFord, Sarah. "Fire and Gold". Youngstown State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1559072363615141.
Testo completoHamzić, Melissa. "Enantio- und Diastereoselektive gold-katalysierte Reaktionen und Aktivitäts-Untersuchungen von Phosphan-Gold-Komplexen in der homogenen Gold-Katalyse". Berlin Mensch-und-Buch-Verl, 2009. http://d-nb.info/995894736/04.
Testo completoSmirnova, Ekaterina. "Polynuclear Gold(I) Catalysts: When One Gold(I) is not Enough". Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/401744.
Testo completoLa investigación de nuestro grupo se centra en la invención de nuevos métodos sintéticos usando catalizadores de oro electrófilos. En un intento de aumentar la electrofilia de los complejos de oro(I) decidimos usar fosfinas orto-boronadas como ligandos ambifílicos. Tras la abstracción de halógeno del complejo neutro de oro(I) obtuvimos el primer clúster Au6(I) con ligandos aromáticos geminalmente diaurados, que muestran actividad catalítica en la ciclación de eninos. Dos clústeres adicionales con sustituyentes ciclohexil y 2-furil han sido sintetizados, con la idea de lograr un mayor entendimiento de la influencia de las propiedades electrónicas de la fosfina en la reactividad. Nuestro siguiente enfoque para aumentar la electrofilia de oro(I) fue la aplicación del ligando 2,6-bis(difenilfosfino)piridina como estrategia para obtener complejos polinucleares de oro(I) que presenten interacciones aurofílicas. Como resultado, se encontró que el complejo linear tetranuclear de oro(I) obtenido no solo catalizaba transformaciones de 1,6-eninos sino también activaba acetona y 1,3-dicetonas para formar complejos de oro(I) y enolatos con una geometría rectangular para los centros de oro(I). Además, en la ausencia de acetona o 1,3-dicetonas observamos hidrólisis de los grupos nitrilo que dieron lugar a la formación de nuevos complejos pentanucleares heterometálicos. Estos complejos mostraron una actividad catalítica excelente en la carbonilación de aminas primarias para formar ureas (intermedios en la síntesis de pesticidas, fertilizantes, tintes y complejos farmacéuticos) bajo condiciones suaves de reacción. Cuando la síntesis del complejo linear tetranuclear de oro(I) se realizó en la ausencia de acetonitrilo, se obtuvo un nuevo complejo de Au8 plano y con forma de anillo. Esto representa un importante descubrimiento en la química del oro, abriendo la posibilidad de entender catálisis en superficies de oro a nivel molecular. En el futuro, las propiedades catalíticas de los complejos de oro(I) polinucleares únicos y con diversas formas presentados aquí serán investigados en mayor detalle.
Research in our group focuses on the invention of new synthetic methods using electrophilic gold catalysts. In an attempt to enhance the electrophilicity of the cationic phosphine gold(I) complexes we decided to use ortho-boronatephosphines as ambiphilic ligands. After abstraction of the halogen from the neutral gold(I) complex we obtained the first hexaauriocluster Au6(I) with geminally diaurated aromatic ring ligands, which shows catalytic activity in the cyclization of enynes. Two additional hexanuclear gold clusters bearing cyclohexyl and 2-furyl substituents on the phosphorus atom have been synthesized, aiming for a better understanding of the influence of the phosphine’s electronic properties in the reactivity of the gold(I) clusters. Our next approach to enhance the electrophilicity of the gold(I) center was the application of the 2,6-bis(diphenylphosphino)pyridine as a strategy to obtain polynuclear gold(I) complexes featuring aurophilic interactions. As a result, linear tetranuclear gold(I) complex was found not only to catalyze different skeletal transformations of enynes but also to activate acetone and 1,3-diketones to form tetranuclear enolate gold(I) complexes with a rectangular geometry of the gold(I) centers in the presence of a mild base. Moreover, in the absence of acetone or 1,3-diketones we observed nitrile hydrolysis that lead to the formation of new pentanuclear heterometallic complexes in good yields. These complexes showed moderate to excellent catalytic activity in the carbonylation of primary amines to ureas (intermediates in the synthesis of pesticides, fertilizers, dyes and pharmaceutical compounds) under mild conditions. When the synthesis of linear tetranuclear gold(I) complex was performed in the absence of acetonitrile, an unprecedented planar ring-shaped Au8 complex was obtained. This represents an important breakthrough in gold chemistry, opening the possibility of understanding catalysis on gold surfaces at the molecular level. In the future, the catalytic properties of the unique and multi-shaped polynuclear gold(I) complexes presented herein will be further investigated.
Dou, Rui. "The Strength and Deformation Mechanisms of Gold Nanowires and Nanoporous Gold". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508553.
Testo completoMatcheswala, Akil Mannan. "GOLD NANOSPHERES AND GOLD NANORODS AS LOCALIZED SURFACE PLASMON RESONANCE SENSORS". UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/60.
Testo completoBouwer, Wendy. "An environmentally sound gold recovery process for small-scale gold mining". Thesis, Cape Technikon, 1999. http://hdl.handle.net/20.500.11838/869.
Testo completoThe gold mining industry has mainly relied upon the use of a highly polluting chemicals, such as mercury and cyanide, to recover gold from its ores. As environmental legislation has become more stringent in all countries and environmental protection has become the focus of world-wide research, development of environmental sound processes has been favoured. The Coal Gold Agglomeration (CGA) process is such a process which was developed some years ago and has the advantage in that gold is recovered by a procedure which has little or no effect on the environment. The CGA process is based on the hydrophobic characteristics of coal, gold and oil. Gold particles which are substantially free become attached to the coal-oil agglomerates during collision, and eventually penetrate into the agglomerates. The resulting agglomerates are recycled to increase the gold loading, separated from the slurry, burnt, ashed and smelted to produce gold bullion. Laboratory scale batch tests were performed on an artificial/synthetic gold ore, containing fine gold powder. The slurry was contacted with a mixture of coal and oil. i.e. coal-oil agglomerates, after which both the agglomerates and ore were analysed for gold. Operating parameters, such as the mode of contact between the coal-oil phase and the gold containing slurry, contact time of the slurry and the coal-oil phase, means of separating the coal-oil gold agglomerates from the slurry, coal to ore, coal to oil and water to ore ratios, type of oil, effect of collectors and the mineralogy of the ore on the gold recovery were investigated. Results have shown that stirring the coal-oil phase and the slug yielded higher gold loadings than shaking and the traditional rolling bottle technique. BI increasing the time of contact between the coal-oil phase and the gold slurry. the final gold loading in the agglomerates increases, until an equilibrium value is reached. An increase in the amount of coal, together with a decrease in the amount of water used in the slurry, has shown to increase gold recoveries. Furthermore, by varying the concentration and volume of a collector. such as potassium amyl xanthate (PAX) enhanced the settling rate and enabled the effectiveness of separation. Moreover, it was found that the gold loading on the coal-oil phase increased after recycling it. Further tests were performed on a real ore sample and after X-ray Diffraction (XRD) analysis, it was found that certain minerals other than gold was transferred to the coal-oil phase. The theoretical foundation of the CGA process is based on the difference in free energy and was expressed as a function of the interfacial tensions and three-phase contact angles between gold, oil and water, together with the ratio of coal-oil agglomerate to gold particle radii, as the free energy is a measure of the thermodynamic stability and hence, partly a measure of gold recoveries, meaningful predictions as to gold recoveries were made by performing a sensitivity analysis on the variables connected to the free energy, It was, however, found that some operating parameters, which were linked to other factors, such as the maximum gold transfer into coal-oil phase and the separation efficiency of the agglomerates. were vital to be taken into account when predictions as to gold recoveries were made. Therefore, the gold recoveries were found to be a function of the thermodynamic stability as well as the maximum gold transfer into the coal-oil phase and the separation efficiency of the agglomerates, The meaningful information gained by performing the theoretical investigations were applied and linked to gold recoveries, thereby providing useful explanations as to the typical gold recoveries obtained during experimentation. A comparative study on mercury amalgamation was done to evaluate the performance of the CGA process. It was found that the CGA process yielded better gold recoveries than amalgamation, which makes it the better process both in terms of recoveries as well as environmental safety, A further application of the theoretical knowledge was, however, very useful to explain the tendency of the CGA process yielding the better results.
Westberg, Fredrik. "Textural characterization of gold in the Björkdal gold deposit, northern Sweden". Thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-82496.
Testo completoYoung, Michaela Nicole 1963. "Characteristics of Skarns Related to Gold Mineralization at Gold Acres, Nevada". Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/558216.
Testo completoSamaimongkol, Panupon. "Surface plasmon resonance study of the purple gold (AuAl2) intermetallic, pH-responsive fluorescence gold nanoparticles, and gold nanosphere assembly". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96549.
Testo completoPHD
Fuxen, Claus. "Adsorption, Struktur und Desorption von Organothiolaten auf Goldsubstraten". [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963053744.
Testo completoValet, Oliver K. "Bildung und Eigenschaften von 2,3-Dimercaptopropansulfonat-Schichten auf Gold(111)". [S.l. : s.n.], 1999. http://www.diss.fu-berlin.de/2000/43/index.html.
Testo completoBrisbin, Daniel Ivan. "Geological setting of gold deposits in the Porcupine Gold Camp, Timmins, Ontario". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq20554.pdf.
Testo completoKadalbajoo, Mridula. "Synthesis and characterization of oligosaccharides tethered to gold films and gold nanoparticles". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/2136.
Testo completoThesis research directed by: Dept. of Chemistry and Biochemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Bomm, Jana. "Von Gold Plasmonen und Exzitonen : Synthese, Charakterisierung und Applikationen von Gold Nanopartikeln". Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6640/.
Testo completoIn this thesis, the synthesis and optical characterization of spherical gold nanoparticles (NP) with diameters larger than ~ 2 nm, gold quantum dots (QDs) with diameters smaller than ~ 2 nm and gold nanorods (NRs) with different lengths are presented. In addition, a novel one-pot synthesis for the preparation of thermosensitive gold QDs is introduced. Gold NP solutions appear red colored due to their strong absorption in the visible range at ~ 520 nm. This absorption band is a result of surface plasmon resonance, which is caused by the coherent oscillation of conduction band electrons induced by an electromagnetic field. In contrast to spherical gold NPs, gold NRs show two surface plasmon bands due to their anisotropic shape, a transverse plasmon band at ~ 520 nm and a longitudinal plasmon band depending on the aspect ratio (length-to-width-ratio) of the gold NRs. If the size of the gold NPs decreases to values below ~ 2 nm, quantum-size confinement occurs and the surface plasmon band disappears. Additionally, the overlap between conduction band and valence band disappears, discrete electronic levels arise and a band gap is created. As a consequence of quantum confinement, the gold QDs show photoluminescence (PL) upon UV-irradiation. The gold QDs synthesized via the one-pot synthesis exhibit a broadband luminescence between 500 nm and 800 nm. The luminescence properties (emission peak, quantum yield, lifetime) strongly depend on the synthetic parameters like reaction temperature, stoichiometry and the surface ligand. Gold NRs and gold QDs were incoroporated into different polymers (e.g. cellulose triacetate). Polymer nanocomposite films showing optical anisotropy are obtainded by stretching polymer films containing gold NRs uniaxial in a tensile test machine. In addition to the optical characterization of gold NRs and QDs, their thermal behavior in solution as well as in different nanocomposites is studied. A shortening of the gold NRs or a transformation into spherical gold NP is observed, if the polymer nanocomposites containing gold NRs are heated above a temperature of 200 °C. The PL of the synthesized gold QDs strongly depends on the ambient temperature. An increase of PL quantum yield (QY) and PL lifetime occur, if the solutions are cooled. The best PL QY of 16.6 % was observed for octadecyl mercaptan capped gold QDs at room temperature, which could be improved to 28.6 % when cooling the solutions to -7 °C. Furthermore, optically anisotropic security labels containing gold NRs and thermosensitive security devices containing gold QDs are developed. Due to their unique optical properties, gold NRs and QDs are interesting candidates for optoelectronical as well as data storage devices and medical applications like biomedical imaging or cancer therapy.
Urban, Scott Andrew. "Gold in the interwar monetary system : evolution of the gold-standard regime". Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568412.
Testo completoSeitkan, Ainur. "Environmental mineralogy of gold recovery from refractory gold-arsenic-bearing Bakyrchik concentrates". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/273373.
Testo completoMather, Diarmid John. "An approach to analyzing gold supply from the South African gold mines". Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1002750.
Testo completoGroen, John Corwyn. "Gold-enriched rims on placer gold grains: an evaluation of formational processes". Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/40977.
Testo completoPlacer gold is frequently reported to assay at overall higher values of tineness than the gold in the rock from which it was liberated. A related phenomenon is the historical discovery of many extremely large gold nuggets (up to 28 lbs) in the southeastern United States that have no apparent source rock. Placer gold grains from the southeastem United States have been examined and found to frequently exhibit the development of nearly pure to pure gold rims around their borders. These gold rims are suggested as a possible cause of the high frneness placer deposits. Formation of very thick rims may also be the cause of the large nuggets. Formation of these gold-enriched rims by the often attributed mechanism of simple silver leaching is disputed on the basis of ineffective mechanisms for the removal of silver from the alloy. Diffusion of silver through the gold at low temperatures proceeds far too slowly to produce the chemical gradients observed in the placer gold grains. Comparison of the complexation capacities of 41 ligands with subsequent modelling of expected complex concentrations in natural stream and stream sediment waters indicates CN- and S2- as the most likely functional ligands for the transport and redeposition of supergene gold. Electrolytic refming of placer Auâ Ag grains is also a process for forming gold-enriched rims that can operate together with secondary enrichment to produce the observed phenomena.
Master of Science
Morse, Kathryn Taylor. "The nature of gold : an environmental history of the Klondike gold rush /". Seattle : University of Washington Press, 2003. http://catalogue.bnf.fr/ark:/12148/cb390579433.
Testo completoJi, Chunxin. "Synthesis, characterization and applications for gold-silver alloy and nanoporous gold nanowires". Available to US Hopkins community, 2002. http://wwwlib.umi.com/dissertations/dlnow/3080690.
Testo completoWu, Yafei. "Gold Source and Deportment in the Daqiao Epizonal Orogenic Gold Deposit, China". Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/78110.
Testo completoPrice, Ryan Cameron. "Nanocrystalline Gold Arylthiolate Molecules". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14051.
Testo completoTrindade, Roberto de Barros Emery. "Catalysed cyanidation of gold". Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8601.
Testo completoBarbosa, Filho Olavo. "Thiocyanate leaching of gold". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46663.
Testo completoEspeland, Erlend. "Gold Nanostructures on Graphite". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22433.
Testo completoSivasubramaniam, Prabalini. "Gold based electro catalysts". Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/193147/.
Testo completoLeeming, Prudence Mary. "Turbidite-hosted gold deposits". Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1005939.
Testo completoMann, P. L. "Surficial placer gold deposits". Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1018245.
Testo completoDavidson, Raymond John. "Innovations in gold extraction". Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1004975.
Testo completoRankine, Graham M. "Gold metallogeny of Australia". Thesis, Rhodes University, 1987. http://hdl.handle.net/10962/d1004676.
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