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1
England, Craig Dennis. "Properties of cobalt/copper and cobalt/palladium multilayers." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185707.
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The physical properties of Co/Cu and Co/Pd magnetic multilayers have been studied. The Co/Cu multilayers were prepared by sputtering, while the Co/Pd multilayers were made by sputtering and molecular beam epitaxy (MBE). Various x-ray diffraction techniques have been used to study the structure of the multilayers. Magnetometry techniques were used to study the magnetic properties. Various optical techniques have been used to investigate the magneto-optical properties. Brillouin light scattering spectroscopy was used to determine the effective elastic constants of the Co/Cu multilayers and the magnetic properties of the sputtered Co/Pd multilayers.
2
Numprasanthai, Apisit Chemical Sciences & Engineering Faculty of Engineering UNSW. "Binary skeletal copper-cobalt catalysts." Publisher:University of New South Wales. Chemical Sciences & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43587.
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Binary skeletal metal catalysts were made by starting with a ternary alloy. The percursor alloys and catalysts were characterised using Optical Microscopy, X-ray Diffractometer, Scanning Electron Microscopy, Inductively Coupled Plasma (ICP) and BET surface area in term of morphologies, phase identification, surface area and pore structure. Skeletal copper catalyst presented high surface areas and consisted primarily of CuAl2 grains, with small well-dispersed areas of the Al-CuAl2 eutectic. The CuAl2 phase, which represented a tetragonal structure, showed large cell volumes resulted in a fine skeleton structure. Binary nickel-copper catalyst composed of three majority phases including Ni2Al3, Cu4NiAl7 and Al. The Cu4NiAl7 was found to be a caustic resistant phase which led to low surface area in the nickel-copper catalyst In terms of the selective removal of aluminium from the copper-cobalt-aluminium alloy to create the binary copper-cobalt catalyst, 11 alloy samples with various compositions were produced following the ternary phase diagram. The surface area and pore size of these catalysts was dependant on the crystal structure of the phases present and the amount of remaining Al. Electrochemical glucose oxidation and carbon dioxide reduction activity have been used for testing the catalyst performance. The electrochemical oxidation of glucose experiment using 11 samples of skeletal Cu-Co catalyst as an electrode showed the results that the significant oxidation peaks were observed in sample 1, 4, 8, 9 and the small oxidation humps were observed in other sample except sample 2. These small peaks resulted from that the glucose molecule had difficulty to absorb on the surface area of the skeletal Cu-Co catalysts electrode. The difficulty may results from very fine pore volume and pore size of the catalysts. In term of assessing the skeletal Cu-Co catalyst with electrochemical reduction of carbon dioxide experiment, the skeletal Cu-Co catalyst sample 7 which presented the highest surface area was selected as an electrode to compare with Cu foil electrode. The result of using skeletal Cu-Co as an electrode indicated significantly higher current. This results from that a skeletal Cu-Co catalyst electrode presented an actual high surface area which leads to more adsorbed regions.
3
Setna, R. P. "Study of the decomposition of copper-cobalt alloys." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239277.
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Richards, G. M. "Deformation processes during creep of copper-cobalt alloys." Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638656.
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Suggu, Santosh Kumar. "Modeling the electrodeposition process of copper on cobalt chrome." Thesis, Wichita State University, 2014. http://hdl.handle.net/10057/10983.
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A simulation is a computer program that helps in creating a real time abstract model of a process. Using simulations the costs of conducting experiments have come down and this has achieved flexibility in terms of optimizing parameters and durations. Electrodeposition is a process that uses electrical current to reduce dissolved metal cations from anode so that they form a metal coating on cathode. Electrodeposition is widely used for many applications varying from anti-corrosion coatings, decorative purposes to high precision nanotechnology cloaking devices. The objective of this research was to predict the electrodeposition of copper on cobalt chrome enabling an efficient optimization of the deposition. The main governing equation used for this model was mass species conservation. COMSOL, finite element software was used to solve the governing equations. The model was simulated to predict coating thickness under different conditions such as, varying current density, concentration and deposition durations. Experiments were conducted to validate the results from the simulation. Electrodeposition was carried in an electrochemical cell with Co- Cr as cathode and Cu as anode with CuSO4 as an electrolyte. Coating thickness was determined using scanning electron microscope (SEM) and thickness gauge. There was an increasing trend in thickness in the both model and experiment when there was increase in current density. Decreasing trend was observed in the thickness in both model and experiment when there was reduction in the conductivity of the electrolyte. Model predicted results of the experiment at lower durations, at higher durations the experimental values deviated from the predicted values. These variations in the results were due to the limitations in the model and experimental verification methods, which could be worked in the future to reduce the variability.<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering
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Cooper, Joshaniel Francis Keany. "Electrodeposition, magnetism and growth studies of cobalt, nickel and copper." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610316.
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Mukhtar, Hassan. "Novel technology for the simultaneous recovery of metals from and the destruction of organic molecules in aqueous systems." Thesis, Brunel University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311238.
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Jiang, Xiong. "Electrochemical studies on the cementation of copper and cobalt with zinc." Thesis, Jiang, Xiong (1987) Electrochemical studies on the cementation of copper and cobalt with zinc. PhD thesis, Murdoch University, 1987. https://researchrepository.murdoch.edu.au/id/eprint/118/.
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The work described in this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system on which some of the new techniques could be proved.
The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc.
The Co(II)/Zn cementation reaction, though thermodynamically highly favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control.
Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed.
The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface.
The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.
9
Jiang, Xiong. "Electrochemical studies on the cementation of copper and cobalt with zinc." Murdoch University, 1987. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060816.135721.
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The work described i n this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were
employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system
on which some of the new techniques could be proved.
The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc.
The Co(II)/Zn cementation reaction, though thermodynamically highly
favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control.
Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed.
The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface.
The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of
benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.
10
McGowan, Ross. "The origin of the Nchanga copper-cobalt deposits of the Zambian copperbelt." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/402419/.
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Tottey, Stephen. "Copper transport and metal specificity in Synechocystis PCC 6803." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391269.
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Parker, Thomas Martin. "The creation of nanoscale structures on copper surfaces." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366007.
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13
Crowder, Janell M. "Homo- and Heterometallic Bis(Pentafluorobenzoyl)Methanide Complexes of Copper(II) and Cobalt(II)." Thesis, State University of New York at Albany, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10680674.
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<p> β-Diketones are well known to form metal complexes with practically every known metal and metalloid. Metal complexes of fluorinated β-diketones generally exhibit increased volatility and thermal stability compared to the non-fluorinated analogues, and thus are used extensively in various chemical vapor deposition (CVD) processes for the deposition of metal, simple or mixed metal oxides, and fluorine-doped metal oxide thin films. Furthermore, the electron-withdrawing nature of the fluorinated ligand enhances the Lewis acidity of a coordinatively unsaturated metal center which facilitates additional coordination reactions. The physical and structural properties of fluorinated β-diketonate complexes are discussed in Chapter 1 and a few key application examples are given.</p><p> The focus of this work is the synthesis and single crystal X-ray structural characterization of unsolvated and coordinatively unsaturated metal complexes of bis(pentafluorobenzoyl)- methanide (L, C<sub>6</sub>F<sub>5</sub>COCHCOC<sub> 6</sub>F<sub>5</sub><sup>-</sup>). In Chapter 2, we present the preparation and isolation of the unsolvated complex [Cu(L)<sub>2</sub>] in pure crystalline form for the first time. We subsequently investigated the reaction of unsolvated [Cu(L)<sub>2</sub>] with sodium hexafluoroacetylacetonate [Na(hfac)] in a solvent-free environment. This reaction allowed the isolation of the first heterometallic Na–Cu diketonate [Na<sub>2</sub>Cu<sub>2</sub>(L)<sub> 4</sub>(hfac)<sub>2</sub>] structurally characterized by single crystal X-ray crystallography. Thermal decomposition of [Na<sub>2</sub>Cu<sub>2</sub>(L)<sub> 4</sub>(hfac)<sub>2</sub>] was investigated for its potential application in MOCVD processes. In the final chapter, we present the first exploration of the anhydrous synthesis of Co(II) complexed with bis(pentafluorobenzoyl)methanide in order to produce a complex without ligated water. Single crystal X-ray crystallographic investigations revealed the isolation of the ethanol adduct, [Co<sub>2</sub>(L)<sub>4</sub>(C<sub>2</sub>H<sub>5</sub>OH)<sub>2</sub>], and following the removal of ethanol, a 1,4-dioxane adduct, [{Co<sub> 2</sub>(L)<sub>4</sub>}<sub>2</sub>(C<sub>4</sub>H<sub>8</sub>O<sub>2</sub>)]. </p><p> In this work, we have provided the first investigation of the synthesis, isolation and single crystal X-ray structural characterization of unsolvated and coordinatively unsaturated Cu(II) and Co(II) complexes of bis(pentafluorobenzoyl)methanide ligand. These studies demonstrate how the electrophilicity of a coordinatively unsaturated metal complexed to highly-fluorinated â-diketone ligands can be utilized for the formation of new adducts or new and interesting heterometallic complexes. This body of work provides a basis upon which future research into unsolvated and unligated bis(pentafluorobenzoyl)methanide metal complexes can expand.</p><p>
14
Rosenberg, Chico L. "Novel precursors for chemical vapour deposition of the metals copper, nickel and cobalt." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/11893.
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Zhang, Yousheng. "Polynuclear magnetic complexes of manganese(II), cobalt(II), nickel(II) and copper(II)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0014/NQ52856.pdf.
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Pérez, Galera Juana María. "Impregnated Cobalt, Nickel, Copper and Palladium Oxides on Magnetite: Nanocatalysts for Organic Synthesis." Doctoral thesis, Universidad de Alicante, 2016. http://hdl.handle.net/10045/57586.
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In this manuscript, the application of different nanocatalysts derived from metal oxides impregnated on the surface of the magnetite in different reaction of general interest in Organic Chemistry is described. In the First Chapter, a cobalt derived catalyst was used to study the hydroacylation reaction of azodicarboxylates with aldehydes. In the Second Chapter, a catalyst derived from copper was used to perform different reactions, including homocoupling of terminal alkynes and the subsequent hydration reaction to obtain the corresponding 2,5-disubstituted benzofurans, the reaction of alcohols and amines (or nitroarenes) to obtain the corresponding aromatic imines, the cross-dehydrogenative coupling reaction of N-substituted tetrahydroisoquinolines using deep eutectic solvents and air as final oxidant. Finally, the formation of benzofurans from aldehydes and alkynes through a tandem coupling-allenylation-cyclization process has been performed. In the Third Chapter, a bimetallic catalyst derived from nickel and copper was used to study the multicomponent reaction between benzyl bromides, sodium azide and alkynes to obtain the corresponding triazoles. In the Fourth Chapter, a catalyst derived from palladium was used in the direct arylation of heterocycles using iodonium salts. Also the synthesis of 4-aryl coumarins through the Heck arylation reaction and subsequent cyclization using the same catalyst is described. In the last Chapter, the use of different eutectic mixtures were studied as alternative media to perform in a single vessel the cyclation reaction of N-hydroxy imidoyl chlorides and alkynes, without any type of catalyst under oxidizing conditions.
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Almeida, Fabio J. D. "Electronic states of epitaxial magnetic layers : metastable FCC iron and cobalt on copper (001)." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335578.
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Altahan, Mohammed Abdulredha. "Cobalt(III), copper(II), and nickel(II) coordination compounds as cations in polyborate chemistry." Thesis, Bangor University, 2017. https://research.bangor.ac.uk/portal/en/theses/cobaltiii-copperii-and-nickelii-coordination-comppounds-as-cations-in-polyborate-chemistry(ba5f189b-2229-481f-9d8d-0bdce17903a8).html.
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This thesis describes the synthesis and characterization of a number of polyborate compounds containing transition metal complex cations; most of these compounds contain 6-membered B3O3 boroxole rings within their structures. A total of twenty-six transition metal complex polyborate salts are reported: one contains the triborate monoanion, [B3O3(OH)4]-, three contain the tetraborate dianion [B4O5(OH)4]2-, twelve contain the pentaborate anion, [B5O6(OH)4]-, three contain the hexaborate dianion, [B6O7(OH)6]2- and five contain heptaborate anions (three of which are [B7O9(OH)5]2-, and two are [B7O9(OH)6]3-). Additionally, two compounds contain two isolated polyborate anion species (octaborate dianion [B8O10(OH)6]2- with pentaborate anion [B5O6(OH)4]-, and triborate anion [B3O3(OH)4]- with [B5O6(OH)4]-). The crystal structures of fifteen salts containing these polyborate anions are reported: [Co(en)3][B5O6(OH)4][B8O10(OH)6]∙5H2O (6), [Co(NH3)6]2[B4O5(OH)4]3∙11H2O (9), s-fac-[Co(dien)2][B7O9(OH)6]∙9H2O (11), [Co(diNOsar)]2[B3O3(OH)4]Cl5∙4.75H2O (12), [Cu(en)2][B5O6(OH)4]2∙2H2O (20), [Cu(pn)2{B5O6(OH)4}][B5O6(OH)4]∙4H2O (22), [Cu(TMEDA){B6O7(OH)6}]∙6H2O (23), [Cu(dac)2(H2O)2][Cu(dac)2][B7O9(OH)5]2∙4H2O (24), [Cu(N,N-dmen)2(H2O)][B5O6(OH)4]2·3H2O (27), [Cu(N,N-dmen){B6O7(OH)6}]·4H2O (28), [Ni(en){B6O7(OH)6}(H2O)2]∙H2O (37), [Ni(AEN)][B5O6(OH)4]∙H2O (38), [Ni(dac)2(H2O-)2][Ni(dac)2][B7O9(OH)5]2∙4H2O (39), [Ni(hn)2][B5O6(OH)4]2 (40), and s-fac-[Ni(dien)2][B5O6(OH)4]2 (41). All the synthesized compounds reported were characterized using spectroscopic (IR, multi-element NMR) and analytical (melting point, elemental analysis, magnetic susceptibility, thermal analysis, powder X-ray diffraction) techniques. The solid-state structures of transition metal complex polyborate salts all display multiple cation-anion H-bond interactions and these undoubtedly play a major role in the energetics of engineering these structures. For example, in compound [Co(NH3)6]2[B4O5(OH)4]3∙11H2O (9), fourteen of the 18 amino hydrogen atoms of the [Co(NH3)6]3+ cation are involved in secondary coordination to anions via H-bonds. Two unique polyborate anions, [B8O10(OH)6)]2- and [B7O9(OH)6]3- have been prepared and characterized in [Co(en)3][B5O6(OH)4][B8O10(OH)6]∙5H2O (6) and s-fac-[Co(dien)2][B7O9(OH)6]∙9H2O (11), respectively. vii The reaction of transition metal complex cations with boric acid in different ratios produced polyborate compounds with different polyborate anions e.g. reaction of [Cu(en)2]2+ with boric acid in 1:10 and 1:5 ratios produce polyborate compounds with pentaborate(1-) and tetraborate(2-) anions, respectively. New polyborate anion structural architectures are identified in this thesis: (i) the pentaborate(1-) anion in [Cu(pn)2{B5O6(OH)4}][B5O6(OH)4]∙4H2O (22) acts as a monodentate ligand coordinated to the Cu(II) cation, (ii) the hexaborate(2-) anion in [Cu(TMEDA){B6O7(OH)6}]∙6H2O (23) and [Cu(N,N-dmen){B6O7(OH)6}]·4H2O (28) coordinates as a tridentate ligand with the Cu(II) cations, and (iii) the hexaborate(2-) anion in [Ni(en){B6O7(OH)6}(H2O)2]∙H2O (37) coordinates as a bidentate ligand with the Ni(II) cation. This is the first time that such coordination mode (i) and (iii) have been observed.
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Wannaparhun, Surasak. "Roles of supercooling and cooling rates in the microstructural evolution of copper-cobalt alloys." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009180.
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Firth, Selwyn R. "Solubility in ammoniacal ammonium salt solutions of copper, nickel, and cobalt components of a waste product produced at Inco's Port Colborne Cobalt Refinery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58741.pdf.
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Clark, Amy Louise. "Mechanisms of metal binding and resistance to toxic metals in bacteria from soils polluted with toxic metals." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341456.
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Heitmann, Sonja. "Cobalt copper multilayers : interplay of microstructure and GMR and recrystallization as the key towards temperature stability." LF, 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971248427.
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Bernau, Robin. "The geology and geochemistry of the Lumwana Basement hosted copper-cobalt (uranium) deposits, NW Zambia." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/63758/.
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The Lumwana Cu±Co deposits Malundwe and Chimiwungo are examples of pre-Katangan mineralized basement that are located in the Domes Region of the Lufilian Arc, an arcuate North neo-Proterozoic fold belt, which hosts the Zambian and Congolese deposits that make up the Central African Copperbelt. The Lumwana deposits are situated within the Mwombezhi Dome; a Mesoproterozoic basement inlier consisting of highly sheared amphibolite grade schist to gneiss units that host the Cu±Co mineralization. Kinematic indicators such as s-c fabrics and pressure shadows on porphyroblasts suggest a top to the North shear sense. Peak metamorphism of 750ºC ± 25ºC and 13 ± 1 Kb indicated by whiteschist assemblages occurred during the Lufilian Orogeny at ~530Ma, with burial depths of ~50km. A major decollement separates the high pressure mineral assemblages of the basement from the lower pressure mineral assemblages of the overlying Katangan Supergroup. The age range and lithologies of the pre-Katangan basement of the Domes Region is similar to the pre-Katangan basement of the Kafue Anticline, which underlies the neo-Proterozoic Zambian Copperbelt deposits situated 220km to the SW. The origin of the protolith to the mineralization is ambiguous at Lumwana with transitional contacts from unmineralized quartz-feldspar±phlogopite basement gneiss to Cu±Co mineralized quartz-phlogopite-muscovite-kyanite-sulphide Ore Schist. The transitional contacts and structural controls on mineralization has led to the hypothesis that these deposits represent metasomatically altered, mineralized and sheared basement, rather than mineralized neo-Proterozoic sediments with amphibolite grade metamorphism. This hypothesis is supported by petrographic analysis, stable isotope analysis (δ34S), whole rock geochemistry, and electron microprobe analysis of ore and host rock assemblages. The transitional contacts observed at Lumwana are due to an alteration event associated with mineralization that removed feldspar from ore horizons resulting in depleted Na and Ca and relatively higher Al components. Sulphides are deformed by the S1 fabric and overprinted by kyanite which formed at peak metamorphism. This indicates that copper was introduced to the basement either syn or pre-peak metamorphism. Post S1 metamorphism with associated quartz-muscovite alteration has remobilized sulphides into low strain zones and pressure shadows around porphyroblasts. δ34SSULPHIDES give values of +2.3 to +18.5‰ that fall within the range of values observed in the Copperbelt of -17 to +23‰. The mechanism of ore formation at Lumwana was dominated by thermochemical sulphate reduction (TSR), indicated by the relatively heavy δ34S values and the absence of the light bacteriogenic δ34S values observed in the Copperbelt. Electron microprobe data of muscovite, phlogopite and chlorite show little variation between early and late mineral phases indicating that metamorphic homogenization of silicate assemblages occurred. The Lumwana deposits are large mineralized shear zones within the pre-Katangan basement. Various styles of basement mineralization are also observed in the Kafue Anticline and the structural controls on mineralization and lithological similarities to the Lumwana deposits suggests that pre-Katangan basement is a viable source for the Cu-Co budget of the Central African Copperbelt and that basement structures had a key role in its formation.
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Andersen, Claire. "Catalyse au cobalt et au cuivre : Couplages croisés entre des (pseudo)halogénures d'alkyle et des réactifs de Grignard." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLET048.
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La majorité des médicaments sur le marché possède un ou plusieurs noyaux aromatiques au sein de leurs structures. Si ces motifs sont souvent essentiels à l’interaction des molécules avec leur cible, leur présence en trop grand nombre peut avoir des conséquences néfastes sur les propriétés physico-chimiques ou sur la toxicité des candidats médicaments. Il est donc intéressant de remplacer ces motifs par des bioisostères d’aryle, notamment par des cycles tendus (cyclopropanes, cyclobutanes, bicyclo[1.1.1]pentanes). Au cours de ce travail de thèse, deux méthodes permettant le couplage entre des (pseudo)-halogénures d’alkyle et des réactifs de Grignard incorporant des cycles tendus ont été développées. La première repose sur un système catalytique au cobalt et permet le couplage des bromures de cyclopropylmagnésium et de cyclobutylmagnésium et des réactifs de Grignard vinyliques avec des iodures d’alkyle. La seconde réaction, catalysée par un sel de cuivre, met en jeu des (pseudo)-halogénures d’alkyle et des réactifs de Grignard bicyclo[1.1.1]pentaniques. Ces deux réactions sont robustes, facile à mettre en œuvre et utilisent des catalyseurs simples et peu coûteux. La chimiosélectivité des couplages est particulièrement attractive et font de ces couplages des outils prometteurs en chimie médicinale<br>Most of the marketed drugs contain one or more aromatic rings in their structure. Even though, those moieties are often essential for a molecule to interact with its target, a too high number of aromatic rings can have a negative impact on the physico-chemical properties and on the toxicity of a drug candidate. It is therefore of high interest to replace a phenyl ring by bioisosteres, such as strained cycles (cyclopropane, cyclobutane, bicyclo[1.1.1]pentane). During the course of this thesis, two methods have been developed for the cross-coupling of alkyl (pseudo)-halides with several Grignard reagents containing strained cycles. The first method relies on a cobalt catalytic system and allow the cross coupling of the cyclopropylmagnesium bromide as well as the cyclobutylmagnesium bromide with alkyl iodides. The cross-coupling has also been extended to the use of alkenyl Grignard reagents. The second method uses a copper salt to achieve the cross-coupling of alkyl (pseudo)-halides with bicyclo[1.1.1]pentane Grignard reagents. Both cross-coupling are robust, easy-to-handle and simple and cheap catalysts are used. As these cross-couplings are chemoselective they are promissing powerful synthetic tools for medicinal chemists
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Audemar, Maïté. "Hydrogénation catalytique de molécules biosourcées." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2323/document.
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Face à une demande sans cesse croissante en ressources fossiles et une prise de conscience sociétale des enjeux environnementaux, un intérêt de plus en plus important est porté à la valorisation de la biomasse lignocellulosique comme source pour l'énergie et la chimie fine.Parmi les molécules d'intérêt pouvant provenir de la lignocellulose, le xylose un sucre en C5 est obtenu par hydrolyse de la fraction hémicellulosique. Ce dernier peut être hydrogéné en xylitol, un édulcorant. Les catalyseurs utilisés pour réaliser cette réaction ne sont pas stables ou sont à base de métaux nobles. Un des objectifs de ce travail est le développement d'un catalyseur actif, sélectif, stable et à base de métaux non nobles pour cette réaction. Des catalyseurs à base de cobalt se sont avérés actifs et sélectifs pour cette réaction d'hydrogénation du xylose en xylitol. La déshydratation du xylose conduit au furfural qui peut être hydrogéné en alcool furfurylique ou hydrogénolysé en 2-méthylfurane. Un catalyseur à base de cobalt supporté sur un support SBA-15 s'est avéré très actif et sélectif pour d'hydrogénation du furfural en alcool furfurylique. Une étude systématique des conditions expérimentales a été réalisée et le catalyseur a été recyclé. L'identification des sites actifs a été réalisée grâce à une corrélation entre les caractérisations physico-chimiques du catalyseur et sa réactivité lors de l'hydrogénation du furfural en alcool furfurylique. L'hydrogénolyse du furfural en 2-méthylfurane a elle été réalisée en présence d'un catalyseur à base de cuivre supporté et a permis l'obtention de 45 % du produit désiré<br>With the increase in the fossil resources demand and a societal awareness of environmental issues, a high interest has been devoted to the use of lignocellulosic biomass as a source for energy and fine chemicals.Among the molecules of interest which come from lignocellulose, xylose, a C5 sugar is obtained by hydrolysis of the hemicellulosic fraction. Xylose can be hydrogenated to xylitol, a sweetener. Today the catalysts used for this reaction are not stable or are based on noble metals. One objective of this work is the development of an active, selective, stable catalyst and based on non-noble metals for this hydrogenation reaction. Cobalt based catalysts have proved to be active and selective for the hydrogenation reaction of xylose to xylitol.The dehydration of xylose affords furfural than can be further converted to furfuryl alcohol by hydrogenation or to 2-methylfuran by hydrogenolysis reaction. A cobalt based catalyst supported on SBA-15 was active and selective in the hydrogenation of furfural to furfuryl alcohol. The study of the experimental conditions was performed and the catalyst was recyclable. The nature of the active site in the hydrogenation of furfural to furfuryl alcohol was determined by a correlation between the physic-chemical properties of the catalyst and its reactivity. The hydrogenolysis of furfural to 2-methylfuran was carried out in the presence of a copper based catalyst and 45 % yield was obtained in liquid phase
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Rozdilsky, Ian. "3-D atomic scale characterisation of growing precipitates." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301389.
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尹業高 and Yegao Yin. "The preparation and structure determination of some copper, cobalt, iron and manganese complexes and the study of their properties." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31235463.
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Yin, Yegao. "The preparation and structure determination of some copper, cobalt, iron and manganese complexes and the study of their properties /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19668570.
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Doddridge, Bruce Germein. "Ligand exchange and substitution on five-coordinate complexes of copper (II), nickel (II) and cobalt (II) /." Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phd641.pdf.
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Проценко, Сергій Іванович, Сергей Иванович Проценко, Serhii Ivanovych Protsenko, Олена Вікторівна Федченко, Елена Викторовна Федченко, and Olena Viktorivna Fedchenko. "Strain resistive properties of films on the basis of copper and cobalt in wide deformation range." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20972.
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Archery, Evelyn. "Simultaneous absorptiometric determination of copper, nickel, iron and cobalt in refinery process streams : potential on-line application /." Link to the online version, 2005. http://hdl.handle.net/10019/957.
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Singh, Hira P. [Verfasser]. "Implementation of a Novel Technology for the Recovery of Cobalt from Copper Smelter Slags / Hira P. Singh." Aachen : Shaker, 2012. http://d-nb.info/1069046183/34.
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Ochoa-Landin, Lucas Hilario 1955. "Geological, sedimentological and geochemical studies of the Boleo copper-cobalt-zinc deposit, Santa Rosalia, Baja California, Mexico." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288901.
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The Santa Rosalia basin is a NW-SE elongated and fault limited basin, which evolved from Upper Miocene to Pleistocene time. The transtensional Upper Miocene Santa Rosalia basin located in central Baja California, consists of almost 500 m of nonmarine to marine sedimentary rocks, with tuffaceous beds interbedded in its lower part. The sedimentary rocks consist of the Boleo Formation, which is 200 to 300 m thick and is dominated in its lower part by marine transgressive sediments and evaporite bodies followed by 170 to 300 m of clastic coarsening upward fan-delta marine-nonmarine sequence. The clastic sequence presents at least three well organized upward coarsing cycles (90-100 m thick each one). Each cycle represents a prograding fan-delta formed probably as a consequence of large and repeated vertical movements of the basin floor with respect to source areas, during the early stage of the opening of Gulf of California. Coeval with the deposition of the clastic sequence of the Boleo Formation there was extensive ash volcanism which originated from a volcanic center north of the basin. Copper-cobalt-zinc stratiform ore bodies (mantos) are hosted within the tuffaceous fine facies in the bottom of each sedimentary cycle. At least five mantos were recognized named as 4, 3, 3(1), 2 and 1. Ore minerals and their textures, the geometry of the mantos and elemental zonation, suggest a diagenetic origin for the different ore bodies. The lowest manto, 4, in the district seems to have a geological correspondence with the Lucifer manganese deposit north of the district associated with hot spring mineralization. Manto 3, 3(1), 2 and others all of which occur at a higher stratigraphic level than manto 4, are associated with mineralized fluids sourced from NW-SE faults. Fluids moving through the conduits crossed an oxidation-reduction boundary with the consequent precipitation of sulfide under reducing conditions. Sulfur and carbon-oxygen isotopes studies support anoxic conditions and a bacteriological origin for the sulfur and a mixture of seawater and freshwater during the formation of the mantos. Cu/Co, Cu/Zn and Co/Zn ratios and Cu-Co and Zn absolute values in the mantos support a horizontal and vertical zoning produced by low temperature up-ward moving solutions. The spatial and temporal correlation of the Boleo deposit with the opening of the Gulf of California indicate that the rifting setting might be the source of the metals and the same time might have induced the migration of the ore fluids.
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Mathew, T. "Synthesis and characterization of mixed oxides containing cobalt, copper and iron and study of their catalytic activity." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2002. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2452.
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Straistari, Tatiana. "Synthesis and study of coordination compounds of cobalt, copper, palladium and nickel with polydentate ligands containing sulfur." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4352.
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Ce travail porte sur la synthèse, la caractérisation et l’évaluation en catalyse de réduction des protons en dihydrogène, de nouveaux complexes de Ni(II), Co(III), Cu(II) et Pd(II) basés sur des ligands de type thiosemicarbazone. La nature de l’espèce catalytique active a été étudiée par voltampérométrie cyclique et des propositions de mécanisme ont été formulés sur la base de calcul quantique de type DFT.Le premier chapitre introduit le contexte scientifique. Le second chapitre concerne la synthèse et la caractérisation des ligands de type N2S2 et des complexes mononucléaires associés de Ni, Cu et Pd. Le troisième chapitre présente la synthèse et la caractérisation de complexes binucléaires de Co et trinucléaire de Ni.Les études électrochimiques de ces complexes dans le DMF en présence d’une source de protons, nous a permis d’évaluer leur efficacité catalytique. Nos résultats montrent que les complexes du Cu et du Pd présentent une vague irréversible spécifique pour la réduction des protons, mais une décomposition est observée durant l’électrolyse. Par contre, les complexes de Ni et de Co ont montré une stabilité électrochimique ainsi que de bonnes performances catalytiques. En particulier, le nouveau complexe mononucléaire de Ni présente des propriétés catalytiques remarquables qui le classent parmi les meilleurs catalyseurs de la réduction des protons décrits dans la littérature. L’ensemble de ce travail fourni une description complète du comportement électrochimique des ligands de type N2S2 complexés à des métaux de transition. Il permet d’envisager des développements futurs dans l’amélioration des propriétés catalytiques de ces complexes<br>This work focuses on the synthesis, the characterization and the catalytic evaluation in the reduction of protons into dihydrogen, of new complexes of Ni(II), Co(III), Cu(II) and Pd(II) based ligands Type thiosemicarbazone. The catalytically active species during the process of the proton reduction was studied by cyclic voltammetry and mechanisms were formulated on the basis quantum chemical calculation.The first chapter introduces the scientific context, the goals and the main objectives of this work. The second chapter concerns the synthesis and the characterization of the N2S2 ligands and their associated mononuclear complexes, Ni, Cu and Pd. The third chapter presents the synthesis and the characterization of binuclear Co and trinuclear Ni based on N2S2 ligand.Electrochemical studies of these complexes in DMF in the presence of a proton source (trifluoroacetic acid), allowed us to evaluate their catalytic efficiency. Our results show that Cu and Pd complexes have a specific irreversible wave for the reduction of protons, but decomposition is observed during electrolysis, which makes these uninteresting complexes for the reduction of protons.On the contrary, Ni and Co complexes showed an electrochemical stability and good catalytic performances. In particular, the new mononuclear Ni complex exhibits remarkable catalytic properties that rank it among the best catalysts for the reduction of protons reported in the literature. All this work provided a complete description of the electrochemical behavior of N2S2 thiosemicarbazone ligands complexed to transition metals. It allows considering future developments in improving the catalytic properties of these complexes
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Straistari, Tatiana. "Synthesis and study of coordination compounds of cobalt, copper, palladium and nickel with polydentate ligands containing sulfur." Electronic Thesis or Diss., Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4352.
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Ce travail porte sur la synthèse, la caractérisation et l’évaluation en catalyse de réduction des protons en dihydrogène, de nouveaux complexes de Ni(II), Co(III), Cu(II) et Pd(II) basés sur des ligands de type thiosemicarbazone. La nature de l’espèce catalytique active a été étudiée par voltampérométrie cyclique et des propositions de mécanisme ont été formulés sur la base de calcul quantique de type DFT.Le premier chapitre introduit le contexte scientifique. Le second chapitre concerne la synthèse et la caractérisation des ligands de type N2S2 et des complexes mononucléaires associés de Ni, Cu et Pd. Le troisième chapitre présente la synthèse et la caractérisation de complexes binucléaires de Co et trinucléaire de Ni.Les études électrochimiques de ces complexes dans le DMF en présence d’une source de protons, nous a permis d’évaluer leur efficacité catalytique. Nos résultats montrent que les complexes du Cu et du Pd présentent une vague irréversible spécifique pour la réduction des protons, mais une décomposition est observée durant l’électrolyse. Par contre, les complexes de Ni et de Co ont montré une stabilité électrochimique ainsi que de bonnes performances catalytiques. En particulier, le nouveau complexe mononucléaire de Ni présente des propriétés catalytiques remarquables qui le classent parmi les meilleurs catalyseurs de la réduction des protons décrits dans la littérature. L’ensemble de ce travail fourni une description complète du comportement électrochimique des ligands de type N2S2 complexés à des métaux de transition. Il permet d’envisager des développements futurs dans l’amélioration des propriétés catalytiques de ces complexes<br>This work focuses on the synthesis, the characterization and the catalytic evaluation in the reduction of protons into dihydrogen, of new complexes of Ni(II), Co(III), Cu(II) and Pd(II) based ligands Type thiosemicarbazone. The catalytically active species during the process of the proton reduction was studied by cyclic voltammetry and mechanisms were formulated on the basis quantum chemical calculation.The first chapter introduces the scientific context, the goals and the main objectives of this work. The second chapter concerns the synthesis and the characterization of the N2S2 ligands and their associated mononuclear complexes, Ni, Cu and Pd. The third chapter presents the synthesis and the characterization of binuclear Co and trinuclear Ni based on N2S2 ligand.Electrochemical studies of these complexes in DMF in the presence of a proton source (trifluoroacetic acid), allowed us to evaluate their catalytic efficiency. Our results show that Cu and Pd complexes have a specific irreversible wave for the reduction of protons, but decomposition is observed during electrolysis, which makes these uninteresting complexes for the reduction of protons.On the contrary, Ni and Co complexes showed an electrochemical stability and good catalytic performances. In particular, the new mononuclear Ni complex exhibits remarkable catalytic properties that rank it among the best catalysts for the reduction of protons reported in the literature. All this work provided a complete description of the electrochemical behavior of N2S2 thiosemicarbazone ligands complexed to transition metals. It allows considering future developments in improving the catalytic properties of these complexes
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Stimeier, Maria [Verfasser]. "Influence of Copper and Cobalt Transition-Metal Complexes onto the High-Pressure Polymerisation of Ethene : Einfluss von Kuper- und Cobalt-Übergangsmetallkomplexen auf die Hochdruckpolymerisation von Ethen / Maria Stimeier." Düren : Shaker, 2020. http://d-nb.info/1210389665/34.
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Butterfield, Martin Thomas. "Surface structure of ultrathin metal films deposited on copper single crystals." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/33132.
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Ultrathin films of Cobalt, Iron and Manganese have been thennally evaporated onto an fcc Copper (111) single crystal substrate and investigated using a variety of surface structural teclmiques. The small lattice mismatch between these metals and the Cu (111) substrate make them an ideal candidate for the study of the phenomena of pseudomorphic film growth. This is important for the understanding of the close relationship between film structure and magnetic properties. Growing films with the structure of their substrate rather than their bulk phase may provide an opportunity to grow materials with novel physical and magnetic properties, and hence new technological applications. Both Cobalt and Iron have been found to initially maintain a registry with the fee Cu (111) surface in a manner consistent with pseudomorphic growth. This growth is complicated by island rather than layer-by-layer growth in the initials stages of the film. In both cases a change in the structure of the film seems to occur at a point where the coalescence of islands in the film may be expected to occur. When the film does change structure they do not form a perfect over-layer with the structure of their bulk counterpart. The films do contain a number of features representative of the bulk phase but also contain considerable disorder and possibly remnants of fcc (111) structure. The order present in these films can be greatly improved by annealing. Manganese appears to grow with an fee Mn (111) lattice spacing and there is no sign of a change in structure in films of up to 4.61 ML thick. The gradual deposition and annealing of a film to 300°C, with a total deposition time the same as that for a 1 ML thick film, causes a surface reconstruction to occur that is apparent in a R30° (√3×√3) LEED pattern. This is attributed to the formation of a surface alloy, which is also supported by the local expansion of the Cu lattice in the (111) direction.
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Carvalho, Luciana Batista de. "Autoxidação dos complexos de tetra, penta e hexaglicina de Ni(II), Co(II) e Cu(II) induzida por S(IV). Determinação de S(IV) e aldeídos por quimiluminescência." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-30032007-153520/.
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A autoxidação dos complexos de Ni(II) e Co(II) com tetra, penta e hexaglicina, em meio de tampão borato, é acelerada por espécies de enxofre (IV) (H2S0<SUB3, HS03-e SO32-). A formação dos complexos de Ni(III) e Co(III) foi acompanhada espectrofotometricamente em 325 e 265 nm, respectivamente. A velocidade da reação de autoxidação do complexo de Ni(II)/Gn aumenta com a concentração de S(IV) e é máxima em pH Ξ8,5. O processo é autocatalítico com Ni(III)ou Co(III)atuando como iniciadores, forma~os pela oxidação espontânea de Ni(II) ou Co(II) pelo oxigênio molecular. A dependência da constante de velocidade observada com a oncentração de S(IV) evidenciou possíveis reações paralelas com formação de um complexo com ligantes mistos antes da etapa da oxidação. A autoxidação dos complexos de Cu(II)com penta e hexaglicina em pH =9 é muito lenta, na presença e na ausência de S(IV).A presença de S(IV) e de traços de Ni(II)ou Co(II) aumenta significativamente a velocidade e a eficiência da reação (período de indução de 0,5 s). O mecanismo envolve uma cadeia de reações e um ciclo redox dos complexos. Acetaldeído e formaldeído inibem parcialmente a reação de autoxidação de Ni(II)/G4 na presença de S(IV) e luminol.O método quimiluminescente desenvolvido pode ser empregado para determinação de formaldeído [(5,0.10-5 - 1,0.10-2) mol L-1] e acetaldeído [(1,0.10-4 - 0,10) mol L-1], não sendo possível detectar separadamente cada um desses aldeídos. Na autoxidação de Ni(OH)2 induzida por S(IV) na presença de luminol ocorre emissão de radiação, possibilitando a detecção de S(IV) na faixa de 5,0.10-8 a 1,0.10-5 mol L-1, com limite de detecção estimado de 1,3.10-8 mol L-1.<br>The autoxidation of Ni(lI) and Co(lI) complexes with tetra, penta and hexaglycine, in borate medium, is accelerated by sulfur (IV) species (H2S03, HS03- and SO32-). The formation of Ni(llI) and Co(lIl) complexes was followed spectrophotometrically at 325 and 265 nm, respectively. The autoxidation rate of Ni(II)/Gn complex increases with S(IV) concentration and is maximum at pH ~ 8.5. The process is autocatalytic with Ni(lIl) or Co(llI) acting as initiators, formed by spontaneous oxidation by oxygen. The dependence of the observed rate constant with S(IV) concentration showed evidences of back or parallel reactions with formation of mixed ligand complex prior to the oxidation step. The autoxidation of Cu(II)/penta and hexaglycine complexes at pH = 9, in the presence and absence of S(IV), is very slow. The presence of S(IV) and of small amounts of Ni(lI) or Co(lI) increases significantly the effectiveness and reaction rate (induction period = 0.5 s). The mechanism involves a radical chain and redox cycling of the metal íon complexes. Acetaldehyde and formaldehyde partially inhibit the autoxidation reaction of Ni(II)/G4 in the presence of S(IV) and luminol. The developed chemiluminescent method can be used for determination of formaldehyde [(5.0.10-5 - 1.0.10-2) mol L-1] and acetaldehyde [(1.0.10-4 - 0.10) mol L-1), being not possible their isolated detection. The S(IV) induced autoxidation of Ni(OH)2 in the presence of luminol, occurs with radiation emission, allowing S(IV) detection in the range 5.0.10-8 to 1.0.10,-5 mol L-1, with detection limit of 1.3.10-8 mol L-1.
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Tonigold, Markus [Verfasser]. "Novel copper- and cobalt-based metal-organic polyhedra and frameworks : synthesis, structure, properties and applications / Markus Stefan Tonigold." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2012. http://d-nb.info/1019563249/34.
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Lidiard, Henrietta M. "Geochemical aspects of copper, cobalt and iodine responsive diseases in the mineralised area of Heasley Mill, North Devon." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332251.
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Royet, Kévin. "La réponse au stress chez les bactéries : réponse au stress métallique chez Pseudomonas putida et au stress rencontré en cours d’infection de plante chez le phytopathogène Dickeya dadantii." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1206/document.
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Les bactéries environnementales font face à de très nombreux stress dans leur milieu devie. Ces dernières doivent s’acclimater rapidement pour faire face à des variations detempérature, des changements d’osmolarité, des changements de pH ou encore descarences nutritives afin de survivre et de prospérer dans leur environnement naturel. Cetravail de thèse s’inscrit dans l’étude de la réponse aux stress chez les bactériesenvironnementales en prenant l’exemple du stress engendré par les métaux chez labactérie modèle Pseudomonas putida et du stress rencontré en cours d’infection deplante chez le phytopathogène Dickeya dadantii. La présence d’un excès d’ionsmétalliques ainsi que les défenses d’une plante sur un phytopathogène entrainent toutdeux un stress oxydatif et peut provoquer une altération membranaire ainsi queprotéique. Ces stress, à première vue éloignés, pourraient ainsi induire des mécanismesde réponses similaires chez les bactéries. La plupart des études de résistance aux stresschez les bactéries portent sur l’étude de gènes sur ou sous exprimés et peuvent alorsmanquer des gènes importants pour la réponse à un stress donné dont l’expressionreste inchangée. Afin d’identifier de nouveaux facteurs de résistance aux stressmétalliques chez P. putida ainsi que de nouveaux facteurs de résistance/virulence chezle phytopathogène D. dadantii, un crible Tn-seq (Transposon-Sequencing) a été réalisé àl’aide de banques de mutants très denses. Les deux cribles ont permis de mettre enévidence le rôle majeur de régulateurs de transcription ainsi que l’importance desmécanismes d’efflux dans la réponse à un stress. Les deux cribles ont aussi mis enévidence l’importance des voies de biosynthèses en acides aminées et acides nucléiques.Enfin, de nombreux gènes à fonction inconnue participent à la survie des deux bactériesen condition de stress. Les résultats obtenus pourraient permettre de développer denouveaux antimicrobiens chez D. dadantii. Les mécanismes de résistance aux métaux etaux antibiotiques peuvent être similaires. Nos travaux améliorent la compréhension desmécanismes de résistance aux métaux et pourraient ainsi permettre de trouver denouvelles molécules à activité antimicrobienne<br>Environmental bacteria have to deal with a number of stresses in their livingenvironment. The bacteria have to adapt quickly to changes in temperature, osmolarity,pH changes or nutrient deficiencies in order to survive and thrive in their naturalenvironment. This thesis work is related to the study of stress response inenvironmental bacteria by taking the example of stress caused by metals in thebacterium Pseudomonas putida model and stress encountered during plant infection inthe phytopathogen Dickeya dadantii. The presence of an excess of metal ions as well asthe defences of a plant on a phytopathogen both cause oxidative stress and can causemembrane and protein alteration. These stresses, at first sight distant, could thus inducesimilar response mechanisms in bacteria. Most stress resistance studies in bacteriafocus on the study of over- or under-expressed genes and may then lack genesimportant for the response to a given stress whose expression remains unchanged. Inorder to identify new metal stress resistance genes in P. putida and newresistance/virulence factors in D. dadantii phytopathogen, a Tn-seq (Transposon-Sequencing) screen was performed using very dense mutant banks. Both screenshighlighted the major role of transcription regulators as well as the importance of effluxmechanisms in the response to stress. Both screens also highlighted the importance ofamino acid and nucleic acid biosynthesis pathways. Finally, many genes with unknownfunction participate in the survival of both bacteria in stress conditions. The resultsobtained could lead to the development of new antimicrobials in D. dadantii. Themechanisms of resistance to metals and antibiotics may be similar. Our work isimproving our understanding of metal resistance mechanisms and could lead to newmolecules with antimicrobial activity
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Vicary, Amanda Denise. "Aspects of nickel uptake and resistance in the yeast Saccharomyces cerevisiae." Thesis, Keele University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368986.
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Malik, M. S. "Comparative studies of the electronic properties of copper tellurite glasses containing nickel, cobalt and lutetium oxides and cupric chloride." Thesis, Brunel University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235019.
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Spicer, M. D. "Higher oxidation state complexes of group Vb and VIb donor atom ligands : Compounds with cobalt(III) and copper(III)." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382971.
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Roebuck, James William. "Reagents for selective extraction of nickel(II), cobalt(II) and copper(II) from highly acidic sulfate feeds containing iron." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/17976.
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This thesis focuses on development of new regents which are suitable for recovering nickel, cobalt and copper from laterite leach solutions, specifically focusing on reagent requirements for novel base metal flowsheets developed by Anglo American. The work aims to design reagents which can extract nickel(II), cobalt(II) and copper(II) from a highly acidic aqueous sulfate solutions whilst showing selectivity over iron(II) and iron(III). Chapter 1 reviews current extractive metallurgy processes for separating and concentrating metals in laterite ores and describes new flowsheets proposed by Anglo American. Chapter 2 considers whether single reagent molecules with sets of tridentate donor atoms can generate sufficiently stable nickel(II) complexes to allow selective extraction of nickel from an aqueous sulfate solution. The salicylaldimines, 3-X-4-alkyl-6-(quinolin-8-imino)phenol, 3-X-4-alkyl-6-(2- methoxyphenylimino)phenol and 3-X-4-alkyl-6-(2-thiomethoxyphenylimino)phenol (alkyl = tert-butyl or tert-octyl; X = H, Br or NO2), were selected for study. The synthesis and characterisation of these proligands and their nickel(II) complexes are reported. XRD structures of Br-substituted salicylaldimines and their nickel(II) complexes are compared and discussed. The 4-tert-octylsalicylaldimines were used to extract nickel(II) from an aqueous sulfate solution with a pH > 2.8 and 3- nitro-4-tert-octyl-6-(quinolin-8-imino)phenol was found to be the strongest extractant in the series with a pH0.5 of 3.5. Computational studies of an analogous series of salicylaldimine proligands in the gas phase calculated the formation energies of their nickel(II) complexes and the predicted trend follows the experimentally determined solvent extraction results. Chapter 3 investigates modifications to phenolic pyrazoles, which are known copper(II) extractants. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)-phenols (X = H, OMe, Br and NO2) was synthesised and characterised. Varying the 6-X-substituent of the phenolic pyrazole altered the strength of copper extraction and 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)-1H-pyrazol-3-yl)-phenol was found to be the strongest extractant in the series. Analysis of XRD structures of related phenolic pyrazoles and their copper(II) complexes showed evidence of inter- and intra-molecular hydrogen bonding. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. The double deprotonation of 4-tert-butyl-(pyrazol-3-yl)-phenol at high pH forms a polynuclear complex in the organic phase with a copper(II) to ligand ratio of 1:1, thereby increasing the mass transport efficiency of copper by the reagent. The synthesis and characterisation of the [Cu16(4-tert-butyl-(pyrazol-3-yl)- phenolate)16(EtOH)4(H2O)2] wheel complex was carried out to demonstrate how such polynuclear copper(II) complexes could be formed under solvent extraction conditions. Chapter 4 explores the solvent extraction of nickel(II) and cobalt(II) by novel combinations of neutral nitrogen-donor heterocyclic ligands with organic acids, such as dinonylnaphthelenesulfonic acid (DNNSAH). The synthesis and characterisation of 2,6-bis(5-alkyl-1H-pyrazol-3-yl)-pyridine, 2-(5- alkyl-1H-pyrazol-3-yl)-pyridine and 5,5'-alkyl-3,3'-bi-1H-pyrazole (alkyl = tert-butyl or nonyl) and their nickel(II) complexes were reported. Also reported are synthesis and 6-N-alkyl-2-(2-pyridinyl)- benzothiazole (alkyl = n-butyl or n-decyl) and 2-(1-Isopropyl-benzimidazol-2-yl)-pyridine. The extraction of nickel(II) from highly acidic mixed metal aqueous sulfate solutions by some of these ligands was studied. These synergistic mixtures demonstrated remarkable strength and selectivity for nickel(II), and cobalt(II) over iron(II). XRD structures of nickel(II) complexes of 2,6-bis(5-tert-butyl- 1H-pyrazol-3-yl)-pyridine, 2-(5-tert-butyl-1H-pyrazol-3-yl)-pyridine and 5,5'-tert-butyl-3,3'-bi-1Hpyrazole with sulfonates or perchlorates as ion-pairs have intermolecular hydrogen bonding interactions between the inner-sphere ligands and the counterions.
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Katombe-Kisumbule, Paul. "Geochemical exploration for copper - cobalt in the Democratic Republic of Congo, Central African Copperbelt: a case study on PR851." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/3035.
Full textAbstract:
The PR851 licence area is located at about 80 km west from the town of Likasi in the district of Haut-Katanga and 175 km north-west of Lubumbashi, the capital city of Katanga Province in the Democratic Republic of Congo. The exploration licence was granted by the government of the Democratic Republic of Congo to First Quantum Minerals Ltd through its Congolese subsidiary Compagnie Minière de Sakania Sprl (CoMiSa Sprl) under certificate N˚ CAMI/CR/70/2003 on the 10th of October 2003 for a period of 5 years with a possibility of renewal for 3 years in respect to the new Congolese mining code. The PR851 area lies on fragments of Mines Subgroup rocks of the Roan Group in the Congolese Copperbelt where most of the Cu-Co and stratiform-stratabound deposits such as Kipushi, Ruashi-Etoile, Kinsevere, Kipoi, Luishya, Luswishi, Shituru, Kamoya, Kambove, Tenke- Fungurume, Shinkolobwe, Swambo, Mindingi and Kamoto among others are found. During the 20th century, the Union Minière du Haut Katanga (U.M.H.K.) undertook mineral exploration in the Congolese Copperbelt and numerous copper- and cobalt-occurrences were identified (for instance Kibamba copper occurrence in PR851 area). From 2003, the Compagnie Minière de Sakania Sprl initiated a grassroots exploration program in PR851 area and geochemical exploration survey as one of the mineral exploration tools was implemented to aim at detecting copper and cobalt concentration in soil. The B horizon of the thick tropical soil in the area was sampled and soil samples were sent to Genalysis laboratories in Johannesburg, Republic of South Africa for main chemical analysis of Cu and Co only, whereas 10% of analyzed samples were dispatched to Perth, Western Australia for quality control analysis. Thresholds for anomalies of copper and cobalt were defined by literature comparison, standard deviations and spatial analysis. The anomalies were tested at a later stage by reverse circulation / diamond drilling during the year of 2005 to 2008 and the Cu-Co resources were estimated by Digital Mining Services of Harare, Zimbabwe in the year of 2008. Geological logging of chips from reverse circulation and diamond drill cores revealed that copper mineralization is represented by malachite, chrysocolla, chalcopyrite and bornite whereas cobalt mineralization appeared in form of heterogenite. The source of supergene mineralization remains unknown. Recommendations have been made to undertake more geological exploration work in order to fully investigate the geological setting and structural architecture of the region, which may result in a better understanding of the Cu-Co mineralization system and ore genesis. The latter has been no consensus up-to-date and different theories have been proposed to discuss the ore genesis, including syn- and dia- genetic, synorogenic and sulphide remobilization to late-to-post- orogenic Cu-Zn-Pb Kipushi-type deposit. However, geological observations favored that the diagenetic and syngenetic models are applicable to numerous deposits in the Central African Copperbelt.
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Van, Wyk Gert Stefanus. "The effect of copper as a chemical promoter on the performance of a cobalt based Fischer-Tropsch synthesis catalyst." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5389.
Full textAbstract:
Bibliography: leaves 46-49.<br>In the light of the fact that copper is used as a promoter for the iron catalyst and that the industry is looking at a commercial FT synthesis cobalt catalyst, it is essential to reinvestigate the effect of copper on a cobalt catalyst. Copper has an effect on the overall activity of iron and cobalt [Kolbel, 1951, J. Schwank, 1991], but the reasons are not clearly understood. In the present study the role of copper as a promoter on the performance of 16.67% (wt) Co/Si02 is investigated with TPR, CO chemisorption, TEM and FT synthesis.
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Fay, Hannah Isabel. "Studies of Copper-Cobalt Mineralization at Tenke-Fungurume, Central African Copperbelt; and Developments in Geology between 1550 and 1750 A.D." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/319897.
Full textAbstract:
The contents of this dissertation fall into two broad areas: geology and history of geology. Although apparently unrelated, the two categories in fact parallel one another. The development of geological systems finds a mirror, on a shorter timescale, in the development of the human understanding of geological systems. The present state of a science - like the present state of an earth system - represents the concatenation of many subtle or evident processes and influences operating over time. Moreover, the events of the past condition the state of the present in science as well as in objects of scientific study. Thus, for instance, to understand why we now hold certain interpretations about the formation of sediment-hosted copper deposits, we must study not only the deposits themselves but the historical development and the philosophical concerns that guided and shaped modern thought about them. In this dissertation the geological and historical aspects are presented in sequence rather than juxtaposed. The geological section comes first, with three chapters detailing the formation and development of the Tenke-Fungurume Cu-Co district and the Central African Copperbelt, followed by another taking a broad view of the mineralogical, geochemical, and metallurgical implications of some of the geological features there. Then follows the history of geology: first two chapters on the role of Georgius Agricola in founding modern geology, and one on how it developed through the following centuries in tune with simultaneous developments in other sciences.
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Amri, Amun. "Structural, optical and mechanical characterisations of nanostructured copper cobalt oxide coatings synthesised via Sol-gel method for solar selective absorber." Thesis, Amri, Amun (2013) Structural, optical and mechanical characterisations of nanostructured copper cobalt oxide coatings synthesised via Sol-gel method for solar selective absorber. PhD thesis, Murdoch University, 2013. https://researchrepository.murdoch.edu.au/id/eprint/28838/.
Full textAbstract:
The search for clean renewable energy sources to fulfil global energy needs, incorporating environmentally-friendly technologies, is currently unabated. Solar thermal collectors are technologies that harness unlimited solar radiation then convert it into usable heat for numerous industries or domestic needs. The solar selective absorber thin film coating is the key component in determining the efficiency of a solar thermal collector. Many challenges still exist in terms of the fabrication of high quality selective absorber material, in order to meet the criteria of better cost-effectiveness and environmentally-friendly characteristics especially in the context of flat-plate absorbers.
In this study, novel copper cobalt oxide (CuxCoyOz) thin film coatings on highly reflective aluminium substrate were synthesised via a facile, environmentally friendly and cost-effective sol-gel dip-coating method. The structural, surface morphology and composition, optical properties, mechanical properties and thermal durability were characterised using a wide range of complementary techniques, namely, XRD, FESEM/SEM, EDX, AFM, XPS, synchrotron radiation XPS and NEXAFS, UV-Vis-NIR, FTIR, nanoindentation and FEM modelling, as well as an accelerated thermal durability test.
The copper cobalt oxide thin films showed a nano-sized grain-like morphology forming a porous surface structure with distinctively high solar absorptance compared to the manganese- and nickel- cobalt oxide coatings. XRD results demonstrated a relatively weak crystallinity of copper cobalt coating through the annealing temperature of 500 °C, the XPS and EDX analyses corroborated the existence of Cu-O and Co-O bonding structures within different copper cobalt oxide composition ratios. The optimised solar absorptance value of 83.4% was achieved from the copper cobalt oxide thin films synthesised using 0.25 M of copper acetate and 0.25 M cobalt chloride precursors ([Cu]/[Co]=1) with the withdrawal rate of 120 mm/min by four dip-drying cycles at annealing temperature of 500°C. Higher absorptance value could be accomplished by a thin film with [Cu]/[Co] of 0.5, however, its reflectance spectra curve was less satisfactory in terms of a good selectivity curve profile.
The difference in [Cu]/[Co] ratios in the synthesis process has a direct influence on the degree of porosity of surface morphology which slightly alters the surface compositions, electronic structure and local coordination of the coatings. The mechanical properties analysis such as the elastic modulus and hardness via a nanoindentation test revealed that the coatings exhibit much higher wear resistance compared to the aluminium substrate especially for [Cu]/[Co] = 1.0. Finite element modelling (FEM) indicated that, under spherical loading conditions, the higher stress and the plastic deformation were predominantly concentrated within the coating layer, with marginal effect on the substrate. The high absorptance value (i.e. without an anti-reflective layer) accompanied by the high wear resistance of copper cobalt oxide made it a very promising candidate for solar selective absorbers application.
Higher annealing temperatures treatment of up to 650 °C improved the crystalline structure of copper cobalt oxide, but it relatively did not change the surface compositions and bonding structures. The absorptance of coatings slightly increased with the annealing temperature up to 550 °C and then decreased from 550 °C to 650 °C due to the increase of scattering from larger crystallite. Even though the elastic modulus and the hardness improved, the wear resistance was slightly decreased as temperature was increased.
To minimize the reflectance of absorber material and protect it from any degradation due to external factors, a silica anti-reflection (AR) layer was fabricated on top of the copper cobalt oxide coatings. The AR layer evidently changed the reflectance spectra which cause the increase of the absorptance value in the UV-Visible-near infrared (UV-Vis-NIR) area and unfortunately also increase the emittance value due to the strong phonon absorption by the silica in the range from mid to far infrared. The optimum absorptance and emittance values were 84.96 and 5.6 %, respectively. The accelerated thermal durability test revealed that the degradation of the copper cobalt oxide with a silica AR layer was more governed by the temperature regime fluctuations compared to the change in exposure time, indicating that the coating is applicable for uses in the low temperature range solar collectors such as for domestic solar water heater (≤ 150 oC).
The sol-gel dip-coating synthesised copper cobalt oxide thin film coatings present high absorptance in UV-Vis-NIR range and low emittance (or high reflectance) in the mid – far infrared range with good mechanical properties. All these attributes render the coatings promising as a solar selective absorber for applications in the solar energy industry. However, further research may require the development of an appropriate anti-reflective layer to maximise absorptance and to minimise emission and then achieve a high selectivity of coatings stack.