Dissertations / Theses: 'Copper and iron'

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Salaudeen, Abibat Abisola. "Switchable iron and copper complexes." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522980.

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Cue´nod, Aure´lie. "Rethinking the bronze-iron transition in Iran : copper and iron metallurgy before the Achaemenid Period." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:6b4a5d9c-55dc-4569-88c4-0814bc50c6d2.

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Iran, a country rich in mineral resources, has a long history of metal working. Copper objects first appeared in the 7th millennium BC and in the following millennia, copper became the material of choice for the production of many objects. Artefacts of iron began to appear in the mid 2nd millennium BC and by the mid 1st, iron had replaced bronze for most uses, but the reasons for this change remain unclear. This thesis seeks to examine the transition from bronze to iron metallurgy from a new angle. By looking at changes in copper-based metallurgy between the Bronze Age and the Iron Age, it attempts to better understand the context in which iron metallurgy developed. To that end, the results of previously published chemical analyses of over 5000 copper-based objects from Iran and neighbouring regions and the lead isotope analyses of about 380 objects were assembled in a database. The tin, arsenic, nickel, antimony and silver concentrations in particular are studied. The data is divided into 16 metal groups based on the absence or presence of the latter four elements. The study of the main groups allows us to describe interesting new patterns of metal movement and recycling. It appears that before the end of the Bronze Age, a number of copper sources and/or trade routes from both east and west declined, leading to a reliance on more local sources for copper and tin in the Iron Age. The practice of recycling from the 3rd millennium BC onward is also evidenced. Overall, it seems that iron appeared within a thriving bronze industry, with a good access to metal resources and a developed understanding of the possibilities offered by copper (alloying, recycling, mixing…). Was it then the more ‘permanent’ nature of iron that attracted the ancient metal-workers and led to its advent?

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Baker, Jonathan Peter. "Iron and copper homeostasis in Staphylococcus aureus." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/9923.

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Staphylococcus aureus is a pathogenic bacterium that causes a wide spectrum of human diseases and is a leading cause of nosocomial infection in the UK. Metal homeostasis is an important aspect of bacterial biology as transition metals such as copper and iron are required as enzyme cofactors but can also be toxic to cells at high concentrations. These metal homeostasis systems can be important for virulence. However, several important aspects of S. aureus metal homeostasis remain to be defined. This project focuses on novel S. aureus iron/Fur gene regulation and copper homeostasis. Fur is a well-described DNA binding repressor protein, found in many pathogenic bacteria. In S. aureus, Fur has been seen to both activate and repress genes in iron replete and iron restrictive conditions, and there is also Fur independent iron regulation. However, the regulatory mechanisms involved remain undefined. This investigation into novel iron regulation identified a new S. aureus iron regulator, LysR. lysR expression was found to be auto-regulated and activated by Fur in low iron. Phenotypic analysis suggested a possible role for LysR in the control of genes of the histidine utilisation pathway, as well as oxidative stress resistance. Two copper responsive operons have been found in S. aureus; copAZ and copB/mco. However, many important aspects of the S. aureus response to copper remain undefined. In this study, copper tolerance was shown to vary between strains and ATCC 12600 was identified as the first hyper copper-tolerant S. aureus, due to a transferable copper-resistance plasmid. A new S. aureus regulator, CsoR, was found to control the copper response of copAZ and both chromosomal and plasmid encoded copB/mco. Finally, this data shows that H2O2 scavenging is an essential S. aureus copper resistance mechanism and that extracellular surface copper toxicity is important in S. aureus.

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Lawal, G. I. "The metallurgy of copper-iron powder composites." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233184.

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Lloyd, Stephen John. "Structure-property relationships in iron-copper multilayers." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624742.

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6

Shi, Xiaoli. "The molecular basis for copper and iron interactions /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.

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Lee, Dok Won. "Structural and magnetic properties of copper/iron multilayers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ44203.pdf.

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8

Parvin, Nader. "Interaction of liquid copper with sintered iron compacts." Thesis, Aston University, 1989. http://publications.aston.ac.uk/11880/.

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Interaction of liquid copper with sintered iron is important in brazing, liquid phase sintering and infiltration. In brazing, the penetration of liquid copper into the pores is to be `avoided', whereas in infiltration processes it is `encouraged', and in liquid phase sintering it should be `controlled' so that optimum mechanical properties are achieved. The main objective of the research is to model the interaction by studying the effect of the process variables on the mechanisms of copper interaction in Fe-Cu and Fe-Cu-C systems. This involves both theoretical and experimental considerations. Dilatometric investigations at 950, 1125 and 1200oC, together with metallographic analyses were carried out to clarify the copper growth phenomenon. It is shown that penetration of liquid copper into the iron grain boundaries is the major cause of dimensional changes. Infiltration profiles revealed that copper penetration between the iron interparticle contact points and along iron grain boundaries is a rapid process. The extent of copper penetration depends on the dihedral angle. Large dihedral angles hinder, and small angles promote copper penetration into the grain boundaries. Dihedral angle analysis shows that the addition of 0.6wt.% graphite reduces the number of zero dihedral angle from 27 to 3o and increases the mean dihedral angle from 9.8 to 41.5o. The dihedral angle was lowest at 1125oC and then increased to higher values as the system approached its equilibrium condition. Elementally mixed (E.M.) Fe-Cu compacts showed a rapid expansion at the copper melting point. However, graphite additions reduced compact growth by increasing the mean dihedral angle. In order to reduce the copper growth phenomenon, iron powder was coated with a thin layer of copper by an immersion coating (I.C.) technique. The dilatometric curves revealed an overall shrinkage in the I.C. compacts compared to their corresponding E.M. compacts. Multiple regression models showed that temperature had the most effect on dimensional changes and density had the most contributing effect upon the copper penetration area in the infiltrated powder metallurgy compacts.

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9

Tapasa, Kanit. "Computer simulation of solute effects in model iron-copper and iron-carbon alloys." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426141.

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Danzeisen, Ruth. "Iron metabolism by BeWo cells : the role of copper and iron in the regulation of placental iron transfer." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364703.

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In this thesis, the regulation of placental Fe metabolism is investigated, using a placental choriocarcinoma cell line (BeWo). Both copper (Cu) and iron (Fe) status are examined for a possible role in the process of placental Fe transfer. Firstly, the involvement of Cu in Fe release is tested. Ceruloplasmin (Cp), a plasma Cu carrier and ferroxidase, is implicated in Fe release from a variety of cell types, but does not stimulate Fe release from BeWo cells. Instead, evidence is presented for a membrane-associated ferroxidase with homology to Cp, expressed by BeWo cells. This placental protein has a peri-nuclear location, but does not co-localise with classical markers for organelles. Expression of the placental Cu oxidase is inversely regulated by Fe status, indicating a possible role in Fe metabolism. Further, it is regulated by cellular Cu status, with protein levels and enzyme activity decreasing in Cu deficiency. In an environment of limited oxygen supply, Cu deficient BeWo cells display a decrease in Fe release, providing additional support for a role of the placental Cu oxidase in Fe release. Secondly, the role of Cu in Fe uptake in investigated. Cu status does not affect Fe uptake through transferrin-receptor mediated endocytosis. However, a non-transferrin dependent pathway of Fe uptake is up-regulated in Cu deficiency. Cu and Fe compete for uptake by this pathway, indicating that it may be mediated by a non-specific transporter, such as DMT1. Finally, the effect of Fe deficiency on Fe transfer by BeWo cells was investigated. It is demonstrated that Fe uptake and Fe release both increase in Fe deficient cells.

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Fosset, Cedric. "Iron and copper interactions in humans : models and mechanisms." Thesis, Robert Gordon University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268863.

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12

Dungworth, David Barry. "Iron Age and Roman copper alloys from northern Britain." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/1024/.

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Rice, James H. "Spectroscopic studies of porphyrins in model bio-molecular environments : photophysical, photochemical and electrochemical studies." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388177.

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14

Young, Steven E. "Crystal chemical control on intra-structural copper isotope fractionation in natural copper-iron-sulfur minerals." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289914.

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The nature of Cu isotope fractionation in natural Cu-Fe-S minerals was investigated through acid ferric sulfate leaching of copper ore from Morenci, Arizona. Copper isotope composition of the derived solutions varies from δ⁶⁵Cu = 0.47‰ to 5.21‰ over the course of progressive copper extraction. High δ⁶⁵Cu values characterize solutions collected in the first half of the leach, while the solutions collected between 35% and 45% copper recovery exhibit lower δ⁶⁵Cu values. This general pattern was observed for both bacterially-mediated and abiotic leaching. Sulfate solutions derived from dissolving pure djurleite show variable Cu isotope compositions as well, although the range is protracted from δ⁶⁵Cu = 0.01‰ to 1.21‰. As the Cu:S ratio of the remaining sulfide decreases, crystal structure parameters change as mineralogy passes through a series of nonstoichiometric copper sulfides. Mineralogy converges to yarrowite near 44% copper dissolution. Crystal chemical studies show that distribution of the two copper-sulfur bond coordination geometries, triangular planar and tetrahedral, in the copper sulfides, approximately corresponds to changes in δ⁶⁵Cu of the leachates. In particular, the proportion of CuS3 relative to CuS4 groups decreases from Cu/S = 2.00 (chalcocite) to 1.40 (geerite). Between Cu/S = 1.40 to 1.00 (covellite), the relative proportion of CuS3 groups increases slightly. Connection between coordination number and Cu isotope fractionation implies affinity of CuS₃ groups for the heavier, ⁶⁵Cu, isotope. This can be justified through bond length-bond strength arguments. Solutions from bornite dissolution vary from δ⁶⁵Cu = -0.79‰ to 1.14‰, with the largest values associated with solutions from early stage of reaction (up to 15% copper removal). Around 25% dissolution, δ⁶⁵Cu of the solution approaches that of the original bornite (δ⁶⁵Cu = 0.02‰). This is explained by disappearance of all remaining CuS₃ groups. Sulfur isotope compositions of solutions and sulfides derived from djurleite leaching were determined to investigate the possibility of intra-mineral fractionation. Very soon after reaction initiation, δ³⁴S of both sulfur reservoirs reach a steady-state with sulfate solutions about 2‰ enriched in ³⁴S relative to residual sulfide. Unlike the case of Cu isotopes, the main partitioning affecting S isotopes is exchange between sulfate and sulfide.

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Zhong, Xu 1966. "Thermodynamics of trace elements As, Bi, Pb, and Sb in copper-iron and nickel-copper matte." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282236.

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A transportation method was used to evaluate the activity coefficients of the minor elements, As, Bi, Pb, and Sb, in both Cu - Fe and Ni - Cu mattes, white metal, and molten Ni₃S₂ as a function of their concentration. Values for the activity coefficients are compared to values obtained by other investigators. With the Cu - Fe mattes and white metal, the analysis was conducted at Cu/Fe molar ratio between 1 to ∞, at sulfur deficiencies from -0.02 to +0.02, and at temperatures between 1493 and 1573 K. Activities of As and Sb in the melts are both concentration dependent at weight percents less than 0.3. No such dependency is observed for Bi or Pb. First and second order self interaction parameters are also reported for As and Sb in Cu - Fe matte. With the Ni-Cu mattes only the sulfur deficiency and the Ni/Cu molar ratio were varied. The experiments were conducted at 1473 K at Ni/Cu molar ratios of ∞, 2, and 1, and at SD values from 0 to -0.1. As and Sb are substantially more stable in Ni - Cu mattes than in Cu - Fe mattes, while for Pb and Bi the presence of Ni does not change the activity of Pb and Bi significantly. The Henrian activity coefficients of these minor elements in both Cu - Fe and Ni - Cu mattes are reported. (Abstract shortened by UMI.)

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16

Hansen, Stephanie Laura. "Nutritional Interrelationships between Iron, Copper and Manganese in Domestic Livestock." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-10292008-130736/.

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Oftentimes the diets of cattle and pigs contain levels of iron well beyond the nutritional requirement of the animal. This superfluous iron may come from feedstuffs naturally high in iron, or from the consumption of soil, though bioavailability of iron from soil is unknown. Additionally, excess iron in cattle diets has been shown to negatively impact the metabolism of manganese and copper, though the molecular mechanism behind this interaction is unclear. The purpose of this research was threefold: 1) to determine the effect of ensiling on bioaccessibility of iron from soil contamination of corn greenchop, 2) to identify proteins important in iron metabolism in bovine and swine, and 3) to determine if these proteins are affected by dietary iron concentration. The results reported herein suggest that bioaccessibility of iron from soil contamination is greatly increased when soil undergoes a prolonged exposure to a low pH environment, such as that found with fermenting forages. These data indicate that very little iron from soil is available to the animal if no prior exposure to an acidic environment occurs. Also, for the first time we report that several proteins known to be essential to iron metabolism in rodents are present in bovine small intestine and liver. Specifically, the iron importer divalent metal transporter 1, the iron exporter ferroportin, and the multi-copper ferroxidase hephaestin were all present in bovine duodenum. In the bovine, reduced iron status, as induced by a primary deficiency of copper, resulted in increased gene expression of divalent metal transporter 1 and ferroportin in duodenum and decreased expression of the ferroportin regulatory hormone hepcidin and divalent metal transporter 1 in liver. Protein expression of ferroportin and hephaestin were also increased in duodenum due to reduced iron status. The addition of excessive amounts of iron to the diets of young calves also appeared to regulate protein expression of transporters important in iron metabolism. Specifically, high iron tended to decreased duodenal protein levels of divalent metal transporter 1 and reduced ferroportin protein levels, though no effect on hephaestin was observed. We also examined iron metabolism in the young pig, in order to examine the effect of an iron deficient diet on expression of these proteins. We found that hephaestin protein in the duodenum was lowered by feeding a high iron diet, and levels of both ferroportin and divalent metal transporter 1 tended to be reduced by high dietary iron compared to pigs fed a low iron diet. Additionally, we found that feeding a high iron diet to pigs negatively impacted liver concentrations of manganese. And feeding a high iron diet to either pigs or calves reduced duodenal concentrations of manganese, suggesting that high dietary iron reduces manganese absorption. Because high iron diets fed to both pigs and calves tended to reduce duodenal levels of divalent metal transporter 1, a protein known in rodents to transport both iron and manganese, it appears that the observed reductions in duodenal manganese concentrations may be a result of reduced transporter availability. Collectively, our data suggest that high dietary iron may negatively affect manganese absorption, and because the iron content of livestock diets is often high, further research is warranted.

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17

Small, Daniel James. "Fractionation of aqueous copper and iron species with ultrafiltration membranes." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1456669.

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18

Wig, Gunjan Mukesh. "Transcriptional regulation of iron and copper homeostasis in Candida albicans." Thesis, University of Leicester, 2014. http://hdl.handle.net/2381/28632.

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The ability of the human pathogen, Candida albicans, to acquire copper and iron from the uncongenial host environment is essential for virulence. Studies in our laboratory have led to identification of the copper-sensing transactivator CaMac1p that regulates genes involved in both copper and iron homeostasis. Described here are our findings of the molecular mechanism involved in the action of Mac1p. Experiments using yeast two-hybrid assays, suggests that the C-terminus domain is involved in protein - protein interactions and that CaMac1p can form homo-dimers in the presence of copper, however it does not undergo intramolecular interactions. The results also indicated that it is likely that the N-terminus domain increases the protein binding activity of the C-terminus domain. For the first time CaMac1 protein was successfully purified and using gel-shift assays CaMac1p was also demonstrated to bind to its own promoter which confirmed the hypothesis that CaMAC1 is self-regulated. This copper-responsive regulation is a key difference when compared to the ScMAC1 (Saccharomyces cerevisiae MAC1) gene, which is constitutively transcribed. The presence of one CuRE (copper response element) site allowed for optimal activation demonstrating the sites are not synergistically associated unlike in S. cerevisiae. Although CaMAC1 also plays a role in iron homeostasis, the exact mechanism of iron responsive gene regulation in C. albicans was as yet unknown; therefore we also studied the role of the putative transcription factor Sef1p as a potential regulator of iron acquisition genes. A novel role of SEF1 in copper homeostasis was detected where Sef1p was found to be involved directly or indirectly in regulation of cupric (as well as ferric) reductase CaFRE7 and copper uptake gene CaCTR1. Hence RT-PCR was also used to analyse the interactions of Sef1p with the other copper and iron responsive regulators - Mac1p and Sfu1p. The transcriptional activator Mac1p was observed to function in a manner different from its traditional role as a positive regulator. CaMac1p acted as a repressor and regulated SFU1 in a copper responsive manner by directly binding to its promoter region. This is the first time that functional evidence (using EMSA) has been provided for this. Sef1p was also found to function together with Mac1p to co-regulate the expression of CaMAC1 itself. This affirms that C. albicans portrays an interdependent regulatory circuit, referred to as the ‘Feed forward loop’. This study elucidates the co-dependent role of these regulators linking iron and copper acquisition which play a vital role in the virulence of C. albicans.

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19

Serrano, Plana Joan. "Bioinspired copper and nonheme iron models for oxygen activation: unprecedented reactivities." Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/398418.

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The oxidation of hydrocarbons is one of the most important processes in the chemical industry, and it is often related to highly toxic reagents that generate a big amount of undesired residues. In sharp contrast, oxygenase enzymes found in natural systems catalyze the oxidation of hydrocarbons in a regio- and stereoselective manner using O2 as sacrificial oxidant. These enzymes, that often contain iron and/or copper in their active site, are the source of inspiration for the development of novel methodologies to perform oxidative transformations in a more environmentally friendly way, using benign oxidants such as O2 or H2O2. In this line, bioinorganic chemistry constitutes a discipline in which chemistry, biology and even physics join with the aim of studying both the structure and reactivity of enzymes. One of the key issues to further develop more effective bioinspired catalysts is learning the basis of their performance. This doctoral dissertation is focused in the development of copper and iron-based synthetic model systems for oxygen activation. On the first place, we have developed a novel unsymmetric ligand inspired in the unsymmetric active site of some copper-based enzymes. This ligand allows the synthesis of various heterodimetallic complexes using copper(I) and a complementary metal that react with oxygen at low temperatures giving raise to the formation of different copper-dioxygen adducts. Also in the topic of copper-based synthetic models, we have developed novel reactivity for a high valent copper(III) compound generated after reaction of the corresponding copper(I) complex and O2 at cryogenic temperatures. We have discovered that this compound is capable of ortho-hydroxylating-defluorinating aromatic carbon-fluorine bonds, which is a very challenging reaction owing to the strong bond dissociation energy associated with this bond. In the second half of the thesis we have turned our interest towards the development of an iron-based synthetic model. Interestingly, when the ferrous complex reacts with peracids at low temperatures it generates a metastable species that is competent for the oxidation of alkanes and olefins. The spectroscopic characterization of this compound points towards a high valent oxoiron compound that has been postulated along the catalytic cycle of the oxidations mediated by nonheme iron systems even though direct detection of such species remained elusive. Thus, the results obtained during this thesis are of great relevance, because for the first time the compound responsible for the oxidation event has been trapped and kinetically interrogated. Finally, the same ferrous precursor reacts with hydrogen peroxide to form a metastable iron(III) species that is an sluggish oxidant but that it is biologically relevant in the catalytic cycle of iron oxygenases. Interestingly, the addition of acid to this compound promotes the formation of a strong oxidizing species that shows great selectivity in hydrocarbon oxidation. This reactivity pattern is reminiscent to the heterolytic O-O lysis in heme systems to form high valent oxoiron compounds
L’oxidació d’hidrocarburs és un dels processos més importants de la indústria química, i sovint està relacionada amb reactius oxidants altament tòxics i que generen grans quantitats de residus. En els sistemes naturals, en canvi, els enzims oxigenases catalitzen l’oxidació d’hidrocarburs de manera regio- i estereoselectiva utilitzant O2 com a oxidant. Aquests enzims, que sovint contenen ferro i/o coure al seu centre actiu, són la font d’inspiració per desenvolupar noves metodologies que permetin realitzar processos oxidatius de manera respectuosa amb el medi ambient utilitzant oxidants benignes com O2 o H2O2. Així doncs, la química bioninorgànica neix de la confluència entre diferents camps de la ciència, des de la biologia a la química, passant per la física, amb l’objectiu d’estudiar l’estructura i la reactivitat de determinats enzims. Sens dubte, un dels punts clau per avançar en el desenvolupament de catalitzadors bioinspirats que siguin més eficaços és aprendre les bases de funcionament dels enzims. Aquesta tesi està centrada en el desenvolupament de sistemes model per l’activació d’oxigen basats en coure i ferro. En primer lloc, hem desenvolupat un nou sistema inspirat en el centre actiu asimètric d’alguns enzims basats en coure. Aquest lligand permet la síntesi de diferents complexos heterodinuclears mitjançant coure(I) i un metall complementari que reaccionen amb O2 a baixa temperatura donant lloc a la formació de diferents adductes coure-oxigen. A continuació, també en el camp de models de coure, hem desenvolupat nova reactivitat per un intermedi en alt estat d’oxidació format després de la reacció d’un complex dinculear de coure(I) amb O2 a -90ºC. Aquest intermedi és capaç d’hidroxilar enllaços fluor-carboni aromàtic, un procés que representa tot un repte ja que aquest és l’enllaç senzill més fort amb carboni. La segona meitat de la tesi està centrada en el desenvolupament d’un sistema basat en ferro. Quan reacciona amb peràcids a baixa temperatura, aquest complex dóna lloc a una espècie meta-estable que és cinèticament competent per l’oxidació d’alcans i alquens. La seva caracterització espectroscòpica apunta cap a una espècie en alt estat d’oxidació que prèviament s’havia postulat en el cicle catalític de les oxidacions mediades per sistemes no hemo però que no s’havia pogut atrapar fins ara. Així doncs, aquest treball és de gran rellevància perquè per primer cop s’ha pogut estudiar amb detall l’espècie responsable de l’oxidació. Finalment, el mateix complex de ferro també reacciona amb peròxid d’hidrogen per donar lloc a la formació d’un hidroperòxid de ferro(III), típicament poc reactius però molt rellevants en el cicle catalític de les oxigenases de ferro. L’addició d’un àcid genera una espècie que no hem pogut detectar però que mostra un gran poder oxidant i una selectivitat remarcable en l’oxidació d’hidrocarburs. Aquest patró de reactivitat concorda amb el trencament heterolític de l’enllaç O-O en sistemes hemo per donar lloc a una espècie d’alta valència de tipus ferro-oxo

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Perron, Nathan Randall. "Effects of polyphenol compounds on iron-and copper-mediated DNA damage /." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219855544/.

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21

Sandhu, S. H. K. "In vivo determination of copper and iron using neutron activation analysis." Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638764.

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The adaptation of two clinical instruments for the in vivo measurement of hepatic levels of copper and iron using neutron activation is described. The neutron activation instrument is based on a 4 GBq ²⁵²Cf neutron source which can deliver different intensities and dose-rates, while the whole body counting facility, located in the adjacent laboratory, comprises of four NaI(Tl) crystals heavily shielded by lead. Due to the close proximity of the two instruments, during a neutron irradiation procedure, the background counts in the detectors in the next room are raised primarily because of iodine activation. Trials of various neutron shielding material have shown that one of the most effective and easily incorporated shields is cadmium placed all around the crystals. The feasibility of measuring the extent of liver copper burden has been established via two different thermal neutron capture reactions employing conventional and cyclic activation. The detection limits (2 standard deviations of the net peak counts) obtained for hepatic copper are 160mg and 200mg for an incident dose equivalent of 30mSv and 39mSv, for the conventional and cyclic methods respectively. Repeated irradiations of liver phantoms containing iron solution have shown that using the delayed, fast neutron reaction, iron can be measured with a reproducibility of 7.3% for a radiation dose equivalent of 36mSv. This relates to a detection limit of 1.2g iron for the liver. The two instruments have been calibrated for the in vivo measurement of copper and iron, and the potential for measurements of chlorine, manganese and magnesium highlighted.

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22

Niestemski, Francis Charles. "Bosonics in the Copper and Iron based High Transition Temperature Superconductors." Thesis, Boston College, 2009. http://hdl.handle.net/2345/1409.

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Thesis advisor: Vidya Madhavan
It has been long established that the phenomenon of superconductivity is administered by lattice deformations (phonons) which act to pair electrons into spinless bosons free to condense into a coherent ground state. This superconducting phase is protected up to a critical temperature above which thermal fluctuations are potent enough to destroy the resistance free phase. The strength of this phonon mediation has been calculated by strong coupling theory and found to be capable of accommodating pairing up to near 40 K. So with the advent of copper-oxide (cuprate) superconductors boasting transitions temperatures exceeding 90 K it was clear that these material represented a new breed of superconducting physics. More than twenty years after the initial discovery of these high-transition temperatures the most basic questions are yet to be answered, the most fundamental of which is by what mechanism does pairing occur? The field splits between those who feel that a boson mediator is still necessary to act as the virtual glue which binds electrons into cooper pairs while others insist that really the Coulomb force alone is enough to induce pairing physics. Even within the boson-seeker community there is no consensus on what particular type of boson is contained in this system whether it be a lattice excitation or spin excitation. This answer has been clouded by previous experimental results on the hole-doped cuprates which have made strong cases for every scenario rendering them largely inconclusive. For this answer though it is possible to explore materials that have not yet been clouded by conflicting results by performing the first high resolution ultra-high-vacuum low-temperature scanning tunneling microscopy (STM) study of an electron-doped cuprate. A distinct and unambiguous bosonic mode is found at energy near 10.5 meV. Through comparison with other experimental data it is found that this mode does not fit the characteristics of a phonon. It is found, through comparison with neutron scattering experiments on the same sample, that this mode is consistent with a spin collective mode. Further more it is found that this mode is linked with the strength of superconductivity nominating it as the possible electron pairing mechanism. Doping and temperature dependence studies are performed to investigate this possibility. Finally the same procedures developed can be applied to the newly discovered iron based superconductors which may represent yet another type of new superconductor physics. Initial results on the first bosonic mode STM study of SrFe$_{2-x}$Co$_{x}$As$_{2}$ and BaFe$_{2-x}$Co$_{x}$As$_{2}$ are presented
Thesis (PhD) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics

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23

Cairns, Pete. "Oxygenates in iron Fischer-Tropsch synthesis : is copper a selectivity promoter?" Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5361.

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Includes synopsis.
Includes bibliographical references (p. 188-197).
The Fischer-Tropsch synthesis is regarded as a stepwise polymerisation reaction between adsorbed hydrogen, carbon monoxide and monomers formed from them. Commercially, a supported precipitated iron catalyst promoted with small amounts of potassium and copper is one of the catalysts used in this reaction. Precipitated iron catalysts are chemically promoted with potassium in order to enhance the product selectivity, while copper is added as a reduction promoter which increases the reduction rate and decreases the reduction temperature of the iron catalyst. The effect of copper on the product selectivity however, remains unclear. This study falls into three distinct categories: firstly the preparation of co-precipitated iron-copper catalysts of varying copper loading and the characterisation of the calcined, reduced and spent catalysts; secondly Fischer-Tropsch synthesis in both fixed-bed and Berty reactors to investigate the effects on product selectivity in regard to copper, and finally the co-feeding of C8 oxygenates, over a pure iron, and an iron catalyst promoted with 50 wt% copper, to investigate the mechanism and pathways of interaction. Co-precipitated iron-copper catalysts were prepared from their nitrates andsubsequently promoted with potassium. Characterisation of these catalysts showedthat the addition of copper formed small (x-ray amorphous) iron crystallites that decreased in size with copper loading. It was also found that the added potassium had a higher affinity for the iron than the copper. Upon reduction the iron crystallites agglomerated to a constant size while the size of the copper crystallites increased with copper loading. Examination of the spent catalysts showed constant ratios of Hägg carbide to magnetite but a decrease in the size of the iron carbide crystallites with increased copper promotion.

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24

Kisslinger, Sandra [Verfasser]. "Reaction behavior of iron- and copper-complexes with tripodal ligands / Sandra Kisslinger." Gießen : Universitätsbibliothek, 2012. http://d-nb.info/1064838146/34.

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25

Peers, Graham Stewart. "Increased metabolic requirements for manganese and copper in iron-limited marine diatoms." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85950.

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Productivity in large areas of the world's oceans is limited by low concentrations of dissolved iron in surface waters. Phytoplankton have adapted to persist in these environments by reducing their requirements for iron (Fe) in key metabolic pathways, in some cases by replacing Fe-containing catalysts with their iron-free functional equivalents. This thesis examines the requirements and biochemical roles for copper (Cu) and manganese (Mn) in Fe-limited centric marine diatoms. A major finding of my research is that diatoms have elevated requirements for Mn and Cu when grown in Fe-deficient seawater. Iron deficiency induces oxidative stress and increases the cellular concentrations of toxic oxygen radicals and damage products in Thalassiosira pseudonana. The increased Mn-requirement is used, in part, to activate Mn-containing isoforms of the antioxidant enzyme superoxide dismutase. Cultures co-limited by Fe and Mn exhibit high levels of oxidative stress and an inefficient detoxification pathway that further reduces cell growth. Diatoms isolated from the metal poor open ocean require more Cu to divide than related species from metal-rich coastal waters. This pattern is in stark contrast to all other known nutritive trace metals. One part of the diatom Cu requirement that is independent of provenance is for efficient Fe transport. The additional Cu requirement of oceanic species appears to be due to the constitutive expression of a Cu-containing electron transport protein, possibly plastocyanin. Coastal species, which have higher Fe-requirements for growth, retain the Fe-containing functional homologue cytochrome c6. By employing metals other than Fe within photosynthesis and antioxidant pathways, marine diatoms are able to increase their fitness in Fe-deficient environments. However, Mn and Cu also occur in low concentrations in the open ocean and thus may co-limit growth of natural populations of phytoplankton. Metal enrichment experiments i

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26

Viik, Rickard. "Surface layer formation on the surfaces of metallic lithium, copper and iron." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257571.

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27

Ikeda, Daiji. "Studies on reactions of alkyl Grignard reagents under iron-copper cooperative catalysis." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/126556.

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28

Goswami, Vandana Esther. "Small Molecule Activation of Copper and Iron Complexes with Bis(oxazoline) Ligands." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0023-3F0E-B.

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29

Liu, Ruiqiang Zhao Dongye. "Fate, transport, and environmental availability of Cu(II) applied in catfish aquaculture ponds and enhanced immobilization of soil-bound lead using a new class of stabilized iron phosphate nanoparticles." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2006%20Fall/Dissertations/LIU_RUIQIANG_19.pdf.

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30

Funk, Maryke. "Screening for childhood anaemia using copper sulphate densitometry." Diss., Access to E-Thesis, 2003. http://upetd.up.ac.za/thesis/available/etd-09192005-135937/.

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31

Chen, Chun-An. "Function and cellular transport of iron chemistry." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092775070.

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Thesis (Ph. D.)--Ohio State University, 2004.
Document formatted into pages. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2005 Aug. 18.

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32

George, Thompson Alayna Michelle. "Molecular Mechanisms of Copper Homeostasis in Gram-negative Bacteria." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/320968.

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Copper is a trace element utilized by organisms as a cofactor involved in redox chemistry, electron transport, photosynthesis, and oxidation reactions. In excess, copper is toxic; it can generate reactive oxygen species causing cellular damage, or poison other metalloproteins by replacing native metal cofactors. Gram-negative bacteria have developed homeostatic mechanisms to maintain the intracellular copper concentration in the face of changing environmental conditions. For Gram-negative enteric bacteria, like Esherichiacoli and Salmonella enterica serovar typhimurium, copper is encountered in industrial and institutional settings, where the metal is used as a broad-spectrum biocide. For environmental bacteria, such as the marine cyanobacterium Synechococcus sp. WH8102, copper stress occurs because human activity changes the concentration of copper in the ocean. This dissertation contains six chapters, relating four stories of our investigations into the molecular mechanisms of copper homeostasis in Gram-negative bacteria. Chapter I contains literature review and background on the implications of bacterial copper homeostasis. Chapter II reports our work investigating the expression of two E. coli proteins, CusF and CusB, upon copper stress; we show that CusF expresses at a ~10-fold molar excess over CusB. Chapter III describes a collaboration between our lab and Jose Argüello's lab at Worcester Polytechnic Institute, and we show that CusF can acquire Cu(I) from CopA. Our results from Chapters II and III show that CusF functions as a major copper chaperone in the periplasm of E. coli. Chapter IV details our work characterizing a novel protein from marine cyanobacteria, Synw_0921. Although Synw_0921 is believed to be involved in copper homeostasis, we show that it is an iron-sulfur cluster protein. Bioinformatic analysis suggests that Synw_0921 represents a new family of proteins that help marine cyanobacteria adapt to copper changes in their unique environment. Chapter V relates our work on CueR and GolS, two homologous sensor proteins with distinct metal-dependent transcriptional activation; we find that the activity cannot be explained by binding affinity differences. Chapter VI concludes with final thoughts on the intersection of biochemistry and molecular biology in the important process of understanding copper homeostasis.

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33

Greentree, Matthew Richard. "Tectonostratigraphic analysis of the Proterozoic Kangdian iron oxide - copper province, South-West China." University of Western Australia. Tectonics Special Research Centre, 2007. http://theses.library.uwa.edu.au/adt-WU2009.0054.

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The Cenozoic Ailaoshan Red River shear zone marks the present day western margin of the South China Block. Along this margin are well preserved late Paleoproterozoic to early Neoproterozoic sedimentary and volcanic successions. This work examines the ages and tectonic environments for the formation of the successions, as well as significance of the regional tectono-magmatic events on the formation of widespread iron oxide-copper deposits. The oldest succession is the Paleoproterozoic Dahongshan Group. A new SHRIMP UPb age of 1675 ± 8 Ma for a tuffaceous schist unit confirms its Paleoproterozoic age. Detrital zircon ages of the Dahongshan Group range between Archean to Paleoproterozoic (ca. 2780 1860 Ma). They include a population of ca. 2400 2100 Ma grains, which have no known source region on the exposed Yangtze Block. Previous geochemical studies of metavolcanic rocks from the Dahongshan Group have suggested that these rocks were erupted in an oceanic setting. However, this study shows that the metavolcanics are extremely altered and cannot be used for reliable tectonic discrimination. Based on the characteristics of sedimentary rocks in the Dahongshan Group, it is suggested that these rocks were deposited in a continental setting. Overlying the Dahongshan Group is a thick sedimentary sequence which has been variably termed the Kunyang, Dongchuan, Huili or Xide Groups. In the past, these rocks have been considered as a Mesoproterozoic rift succession. However, no precise age constraints were available for the succession. In this study, this sequence is found to contain at least two separate tectonostratigraphic units. The oldest (ca.1140 Ma) is comprised of alkaline basalt with a geochemical and isotopic character similar to that of modern intracontinental rift basalts. The presence of Cathaysia-derived sediments in this unit indicates sedimentary transportation from the southerly Cathaysia Block to the northerly Yangtze Block (in present coordinates) in South China at that time, which suggests an impactogen scenario. The thick sedimentary sequence of what has traditionally been defined as the Kunyang Group has been found to have significantly younger depositional age of ca.1000 960 Ma. The composition of sedimentary rocks and the provenance of detrital zircons from the Kunyang Group are consistent with a foreland basin setting. The depositional age of this sequence coincides with the timing of Sibao Orogeny as determined elsewhere in the South China Block. Summary Page ii Numerous iron oxide - copper (gold) deposits occur within the rocks of the Dahongshan and Kunyang Groups. Previous studies have classified these deposits into two deposit styles: the Dahongshan-type Paleoproterozoic VMS mineralisation hosted within the Dahongshan Group, and the Dongchuan-type diagenetic carbonate and shale-hosted deposits hosted within the Kunyang Group. However, both deposit types share similarities with the iron oxide copper (gold) deposit class, such as stratabound disseminated and massive copper ores, abundance of iron oxide occurring mostly as low Ti - magnetite and haematite, and variable enrichments in Au, Ag, Co, F, Mo, P and REE. 40Ar/39Ar data from both deposit types indicate mineralisation ages of ca. 850 830 Ma and 780 740 Ma.

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34

Quah, Yin Lynn. "Cytotoxic mechanisms following the overloading of isolated rat hepatocytes with iron versus copper." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ51595.pdf.

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35

Toijer, Elin. "Assessment of primary damage and copper precipitation in cast iron in repository conditions." Thesis, KTH, Fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154791.

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36

LeCloux, Daniel D. (Daniel David) 1970. "Synthesis and reactivity of copper(I) and iron(II) carboxylate-bridged dimetallic complexes." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50411.

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37

Avendano, Cecena Lizeth. "The effect of ocean acidification on the organic complexation of iron and copper." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/377295/.

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Trace metal biogeochemistry is projected to be affected by ocean acidification. The understanding of the effects is of particular interest, as trace metals such as Fe and Cu are known for their significant biological roles. Dissolved Fe and Cu in seawater occur predominantly in the form of metal organic complexes. This thesis has investigated the influence that ocean acidification may have on the chemical forms (speciation) of dissolved Fe and Cu in seawater, focusing on their organic complexation, in order to provide a first insight into the possible future changes in their cycling and bioavailability. Competitive Ligand Exchange Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) was used as an analytical technique throughout this PhD work to determine Fe and Cu organic binding ligand characteristics. Organic Fe complexation was determined at current seawater pH in the high latitude North Atlantic (HLNA), which is an area of climate interest due to the importance of iron limitation on phytoplankton productivity and hence the carbon cycle. Main findings indicate that iron biogeochemistry in surface and subsurface waters of the HLNA is controlled by a combination of phytoplankton iron uptake and microbial iron binding ligand production, whilst in deep waters ligand saturation was evident, suggesting that additional Fe would be removed by scavenging or precipitation. The effect of ocean acidification on organic complexation of Fe and Cu was determined in the northwest European shelf seas, during the first UK Ocean Acidification consortium programme research cruise. Results suggested that a decrease in surface ocean pH will potentially result in a reduction of the free and inorganic metal fraction (Fe'), and also in an increase in the organically complexed iron fraction. Direct impacts on Fe bioavailability, however, are difficult to quantify, as the overall iron solubility, and hence its bioavailability, is controlled by the interrelationship between inorganic solubility, organic complexation, redox chemistry, and phytoplankton-trace metal feedback mechanisms. No significant effects were observed of a decrease in pH on the organically complexed Cu (II) fraction, or on the overall free and inorganically bound fraction (Cu'). Consequently, it is not clear so far whether Cu ligand production will be affected by ocean acidification, or the possible effects on its toxicity. In addition, surface water trace metal distribution in the northwest European shelf seas was assessed. Dissolved metal concentrations of Cd, Cu, Fe, Ni and Zn appeared to be significantly influenced by riverine inputs in the study area; whereas surface seawater pH was not evident as a controlling factor. The diversity of the chemical and biological processes controlling Fe and Cu biogeochemistry, and the way in which they will be altered by ocean acidification, is likely to be complex.

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Abdul, Rahim Khairuddin bin. "Interactions of arbuscular mycorrhizal symbionts with arsenic and other potentially toxic elements." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326752.

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39

Fernandez, Alvaro. "Moving from rocks to hydrologic systems are Cu, Fe, and Zn isotopes fractionated during weathering? /." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.

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40

Ashton, Mark. "Behaviour of metals as a function of strain-rate and temperature." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/10449.

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Five materials, copper (two versions), iron, and armour plate steel (two versions) have been tested at different strain-rates and temperatures. All tests were in compression. The materials were studied to provide experimental data for input into hydrocode models of armour behaviour by the Defence Research Agency, Fort Halstead. A wide selection of metals was examined so that comparisons could be drawn between modelling the behaviour of face centred and body centred cubic metals, and to carry out a broader investigation into how the results obtained were affected by the test methods. Experiments were performed at temperatures from -100°C to 20°C and mean plastic strain-rates from 10-3 to 103 S-l, using a Split Hopkinson Pressure Bar (SHPB) system for high strain-rates and a Hounsfield 50 kN machine for quasistatic conditions. The stress-strain behaviour of the materials as a function of temperature and strain-rate was then determined. The effects of interfacial friction on the measured compreSSlve properties of copper and the armour plate steels have been investigated. Since the coefficient of friction was the critical parameter, ring tests were carried out and the Avitzur analysis applied. In general, the coefficient of friction decreased with increasing strain-rate and temperature. The tested specimen's appearance indicated the same friction trends. Hydrocode modelling of the SHPB system produced corrections to the flow stress, to compensate for interfacial friction, that agree well with those predicted by the Avitzur analysis. Deformed finite element mesh plots analysed in conjunction with barrelled specimens have given a clearer insight into the mechanisms of interfacial friction. The Armstrong-Zerilli constitutive models have been applied to copper, iron and armour plate steel results corrected for thermal softening and specimen-platen interfacial friction. These models have been shown to provide a reasonable description of the materials' behaviour. The research investigation has shown that in order to obtain fundamental stressstrain behaviour of the materials, then corrections must be applied, which can be quite significant. These corrections must take into account the effects of material thermal softening and the specimen-platen interfacial friction.

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41

Lorentsen, Odd-Arne. "Behaviour of nickel, iron and copper by application of inert anodes in aluminium production." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-68.

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A thorough investigation was performed on the behaviour of Ni, Fe and Cu oxides dissolved in cryolite melts, and the solubility of these species was measured as a function of alumina content, NaF/AlF₃ molar ratio (CR) and temperature. Predominance area diagrams showing the solid phases containing Ni, Fe and Cu, respectively, as a function of the partial oxygen pressure and the alumina activity at 1020 ^oC were constructed. These diagrams were based on present emf and solubility measurements.

The interpretations of the solubility measurements for the oxides of Ni and Fe gaveconclusive and consistent results. The oxides of Ni and Fe exhibit decreasing solubility with decreasing temperature and with increasing alumina concentration. The Ni(II) concentration decreased from 0.32 wt% in cryolite to 0.003 wt% in alumina-saturated melts, while that of Fe(II) decreased from 4.17 to 0.32 wt% in similar melts. FeO and NiO are stable solid phases at low alumina concentrations, while FeAl₂O₄ and NiAl₂O₄ are stable at high concentrations. The alumina concentrations corresponding to the points of coexistence between FeO and FeAl₂O₄ and between NiO and NiAl₂O₄ were determined to be 5.03 and 3.0 wt% Al₂O₃, respectively, corresponding to the following Gibbs energy of formation from the oxide compounds,∆G⁰_fNiAl2o4 = –28.6 ± 2 kJ/mol and ∆G⁰_{f FeAl2O4} = –17.6 ± 0.5 kJ/mol.

The solubilities of FeAl₂O₄ and NiAl₂O₄as a function of the CR were investigated in alumina-saturated melts at 1020 ^oC. For both compounds a maximum solubility was found at CR ~5, being 0.008 wt% Ni(II) and 0.62 wt% Fe(II). The results are discussed with respect to the species present in solution. Both Fe(II) and Ni(II) dissolve as fluorides with different numbers of associated “NaF’s”. Ni(II) seems to form Na₃NiF₅ in melts with molar ratios 2 to 12, while Fe(II) is present as NaFeF₃ in acidic (CR 3–10) melts and as Na₃FeF₅and probably some Na₄FeF₆ in basic melts (CR > 3).

The solubility of both Cu oxidation states Cu(I) and Cu(II) decreases with decreasing temperature. The solubilities of Cu(I) initially decreased with increasing alumina concentration, showing a minimum at a certain alumina concentration followed by an increase. The solubilities were 0.36 wt% Cu(I) and 0.92 wt% Cu(II) in cryolite, and 0.30wt% Cu(I) and 0.45 wt% Cu(II) in alumina-saturated cryolite at 1020 ^oC.

At 1020 ^oC the solubilities of Cu₂O and CuO were little influenced when changing the CR from 3 to 8 in alumina-saturated melts (~0.30 wt% Cu(I) and ~0.45 wt% Cu(II)), but there was an upward trend for CR < 3. Solubility measurements for CuO in alumina-saturated melts at CR 3.0 to 1.2 clearly showed that the saturation concentration is dependent on both temperature and melt composition.

Copper ions in solution show a complex behaviour, since they form fluorides and oxycomplexes simultaneously. The extent of co-existence of Cu(I) and Cu(II) in the same melt is also considerable, and it is depending on the alumina activity in the melt. According to thermodynamics the stable copper oxide phases at high alumina activities are the aluminates CuAlO₂ and CuAl₂O₄. However, no clear changes in the solubilities were found for the points of coexistence between Cu₂O and CuAlO₂ and CuO and CuAl₂O₄, respectively, as was the case for Ni(II) and Fe(II). Although there are uncertainties regarding the thermodynamic data available for the formation of copper aluminates, models for the dissolution mechanisms and for the species present in the melt are suggested. Cu(I) seems to form mainly CuF at low alumina contents, while Na₅CuO₃ dominates at higher alumina concentrations. Likewise, Cu(II) seems to form CuF₂, but the concentration of CuF₂ decreases with increasing alumina content. The species that gave the best fit for the cupric oxy-complexes was Na₁₆CuO₉, and the amount increased with increasing alumina content.

Cermet anodes were prepared with a NiFe₂O₄-based oxide phase mixed with a ~20 wt% copper-rich metal phase. The electrical conductivity for these materials was measured as a function of temperature, showing semiconductor behaviour in the temperature range from room temperature to 1050 ^oC. The highest electrical conductivity measured was ~30 S/cm at 1000 ^oC, which is on the low side for use as an anode material for aluminium production.

Three cermet anodes were tested by electrolysis for 48 hours. After the experiments the anodes were examined with SEM. There was no metal phase present in the outer 100 µm of the anode, not even pores were observed that could indicate where the metal grains had been. A copper-rich phase was found in one case ~2 mm from the outer surface, and it is believed that copper diffuses out of the anode.

The cermet anodes dissolved slowly in the electrolyte during electrolysis. The steady state concentrations of Fe and Cu in the electrolyte were below the saturation concentrations, while the concentration of Ni was 3 - 4 times above saturation. The dissolution of the anode does not fit a first order mass-transport model, but it can probably be explained by a controlled dissolution mechanism with some additional disintegration/spalling of the anode material. Further work is needed to draw a firm conclusion. In general, correct solubility data for the anode constituents are needed to make a proper evaluation of various anode materials. Perhaps the first order mass-transport model agrees for some materials, but based on the present results it seems untenable for cermet materials made of NiFe₂O₄ with a copper-rich metal phase.

The solubilities of the oxides of Ni(II) and Fe(III) are very low for the alumina-saturated melt used during electrolysis, which make them promising candidates for inert anodes. However, if nickel aluminate, which is an insulator, is formed and deposited on the anode surface, it is a cause of concern. Fe(II) aluminate is not expected to form on the anode surface, since Fe(III) is the stable oxidation state in the presence of oxygen gas. However, solid Fe(II) aluminate may be formed in the bulk of the electrolyte where the partial oxygen pressure is lower.

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42

Aulinas, Silvia Batchelli. "Binding of iron and copper to humic-rich colloids in estuarine and coastal waters." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165418.

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The main goal of this thesis was to develop a multi-technique approach to characterise high molecular weight (colloidal) dissolved organic matter (DOM) occurring in estuarine and coastal marine environments and to investigate how these bulk properties may relate to their ability to influence the physicochemical speciation of metals such as iron and copper. This characterisation was undertaken systematically on the pre-filtered (0.4 μm) estuarine or marine sample, referred to here as the ‘bulk’, as well as on the ultrafiltered (< 5 kDa) and colloidal (> 5 kDa) fractions. Three successive studies were carried out. The first one took place in the estuarine mixing zone of a high pH, low turbidity black water river (River Thurso) and the other two in the receiving coastal waters (Thurso Bay). The optical and size distribution properties of these waters were examined in detail in the first study while their iron and copper-binding properties were examined in the second and third studies, respectively. Size fractionation results showed that the proportion of colloidal to soluble organic carbon (DOC) tended to decrease from the upper estuary (~ 60%) to coastal waters (~ 20%). With respect to trace metals, similar trends were observed as one progressed from the mouth of the river towards the open sea. In relation to their molecular absorption, fluorescence and size fractionation properties, both River Thurso DOM and Nordic Reservoir NOM Reference Material presented the same characteristics and mixing behaviour, indicating the dominance of humic and fulvic substances in the Thurso river-ocean system. The river-borne, humic colloids underwent two types of transformations upon mixing with the seawater end-member. The first one was the coiling or contraction of individual macromolecules ―monomers― with increasing salinity. The second one was the concurrent aggregation of these small monomer units (d = 2 – 4 nm) to form entities that were still colloidal, i.e. smaller than 0.4 μm. As a result of extensive association of iron and copper with the colloidal and soluble fractions respectively, not only organic carbon but also iron and copper behave conservatively in the River Thurso estuary. Throughout the coastal region of freshwater influence (S = 29 - 35) colloidal iron accounted for 30 - 80% of total dissolved iron and was present as iron-humic complexes supplied by the river and showing a uniform stability constant (log KFe’HS’ = 11.3  0.1, i.e. log KFe3+ HS’ = 21.3  0.1). Soluble iron was found to be largely complexed to ligands of marine origin with log K’Fe’HS’ = 11.9  0.1, thus revealing for the first time a difference between the iron-binding strengths of colloidal and soluble ligands. Terrestrial colloidal iron was found to be entirely, if slowly (~ 10 hours), accessible to the added competing ligand 2-(2-thiazolylazo)-pcresol (TAC) used for the determination of K’Fe’HS’. Furthermore, iron appeared to play a role in holding these terrestrial colloids together. Evidence for this came from variations in humic fluorescence intensity over time in response to dissociation of the ironhumic colloidal associations induced by a chelating resin. These results are consistent with the concept that iron derived from a peat-draining river is strongly but reversibly bound to humic substances and remains so under marine conditions. In the same coastal region, two types of high-affinity ligands binding over 99.99% of total copper were detected. The stronger ligand (L1, log KCu2+L1’ = 15.5 - 16.1), of riverine origin, was present in very low concentrations of 1 - 4 nM that correlated with ―but systematically fell short of― total copper concentrations. Its conditional binding constant tended to increase with salinity, with most of the increase taking place in the near-field portion of the river plume. The weaker, more abundant ligand (L2, log KCu2+L2’ = 11.8 - 12.8) was present in total concentrations of 60 – 170 nM and had a controlling influence on the value of the labile (i.e. inorganic) copper concentration which ranged from 0.001 to 0.0001 nM. Both organic ligands were fairly evenly partitioned between soluble and colloidal phases but their sources appeared to differ significantly. Ligand L1 appeared to be of riverine origin (although one cannot exclude active microbial production, as opposed to passive release from peat) while ligand L2 distributions suggested in situ production within Thurso Bay.

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43

Harry, Thomas John. "Computer simulation of point defects and dislocations in iron containing small concentrations of copper." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397387.

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44

Williams, Claire Louise. "The effects of molybdenum, iron and sulphur on copper metabolism and physiology of sheep." Thesis, Open University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403832.

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45

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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46

Ali, H. Saad Moh'd. "Selective catalytic oxidation of ammonia using copper and iron supported on ZSM-5 catalysts." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525661.

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47

Ohta, Takehiro. "Studies on C-H Bond Activation by Dinuclear Iron and Copper Enzyme Model Complexes." Kyoto University, 2000. http://hdl.handle.net/2433/180931.

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48

Haynes, John Stephen. "Spectroscopic and magnetic properties of pyridine and pyrazine complexes of divalent iron and copper." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25821.

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Magneto-structural correlations have been made for a number of pyridine and pyrazine complexes of iron(II) and copper(Il), involving anions of a range of coordinating abilities, for example, sulfonate, RS0₃⁻ (where R is CF₃, CH₃ or p-CH₃C₆H₄); halide, Cl⁻ Br⁻ or I⁻; pseudohalide, NCO⁻ or NCS⁻; perchlorate and hexafluoroarsenate. Structure was determined by infrared, electronic and Mössbauer spectroscopy and differential scanning calorimetry, and, in some instances, by single-crystal X-ray diffraction. Spectroscopic results were used to investigate the nature of both anion and neutral ligand coordination. In complexes of stoichiometry ML₄ (RS0₃)₂ (where M is Fe or Cu, L is pyridine, pyrazine or 2-methylpyrazine and R is CF₃, CH₃ or p-CH₃C₆H₄), the neutral ligands were found to adopt a unidentate mode of coordination. For several of these complexes, X-ray crystallography revealed a square-planar array of pyridine ligands around the central metal, with anions coordinated in a unidentate mode above and below this plane. A monomeric molecular structure results in which the paramagnetic centres are well isolated from each other giving rise to magnetically-dilute species. In complexes of stoichiometry M(pyz)₂X₂ (where M is Fe or Cu and X⁻ is CF₃S0₃⁻, CH₃S0₃⁻, Cl⁻, Br⁻, I⁻, C10₄⁻ or NCS⁻), pyrazine was found to coordinate through both nitrogen donor atoms and inorganic coordination polymers were produced. X-ray crystallography revealed a two-dimensional lattice in Cu(pyz)₂(CH₃S0₃)₂ with two distinct kinds of bridging pyrazine groups and monodentate sulfonate anions. For the remaining bis(pyrazine) complexes, spectroscopic evidence supports similar structures with unidentate anion coordination and bidentate bridging pyrazine ligands leading to sheet-like polymers. Cu(pyz)₂(CH₃S0₃)₂ and Fe(pyz)₂(NCS)₂ exhibit magnetic susceptibilities which reveal the antiferromagnetic nature of these materials (ˣmax at temperatures of 7.0 and 8.0 K respectively); the data were analysed in terms of a two-dimensional Heisenberg model. For the copper complex, in which the structure shows stronger pyrazine coordination along one dimension, the data were also analysed in terms of a linear chain model. Mössbauer spectroscopy showed Fe(pyz)₂(NCS)₂ to undergo a transition to a magnetically-ordered state at 9.2 K. The magnitude of the exchange coupling through bridging pyrazine in Fe(pyz)₂X₂ complexes (where X⁻ is CF₃S0₃⁻, CH₃S0₃⁻, Cl⁻, Br⁻, I⁻ or C10₄⁻) is considerably less than that present in either Cu(pyz)₂(CH₃SO₃)₂ or Fe(pyz)₂(NCS)₂. Spectroscopic evidence indicates that for Fe(py)₂(CF₃S0₃)₂ and complexes of stoichiometry M(pyz)X₂ (where M is Fe or Cu and X⁻ is CF₃S0₃⁻, p-CH₃C₆H₄S0₃⁻, Cl⁻ or NCO⁻) bridging anionic ligands are present and for the mono(pyrazine) complexes the neutral ligand also coordinates in a bridging mode. Fe(pyz)(CF₃S0₃)₂, Fe(pyz)(NCO)₂ and Cu(pyz)(CF₃SO₃)₂ all exhibit magnetic susceptibility data characteristic of antiferromagnetic materials (ˣmax at temperatures of 4.4, 38 and 7.0 K respectively). The magnetic susceptibilities for these materials were analysed in terms of the two-dimensional Heisenberg model and a linear chain model. Mössbauer spectroscopy shows both Fe(pyz)(CF₃S0₃)₂ and Fe(pyz)(NCO)₂ to undergo a transition to long-range magnetic ordering at temperatures of 3.9 and 27.0 K respectively. Low-temperature (4.2-130 K) magnetic susceptibility measurements for the iron(II) sulfonate compounds, Fe(RS0₃)₂ (where R is F, CF₃, CH₃ or p-CH₃C₆H₄) are reported. For the compounds where R is F, CF₃ or p-CH₃C₆H₄ the magnetic moment data were assessed in terms of crystal-field splitting effects. The magnetic moment data for ɑ and β forms of Fe(CH₃S0₃)₂ are indicative of antiferromagnetic exchange interactions and the characteristics of the susceptibility curve for the β isomer are explained on the basis of a transition from short-range to long range three-dimensional magnetic ordering at 22 K.
Science, Faculty of
Chemistry, Department of
Graduate

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49

Xu, Yinhui Zhao Dongye. "Removal of copper(II) and lead(II) from soils by poly(amidoamine) dendrimers and reductive immobilization of chromium(VI) by stabilized zero-valent iron nanoparticles." Auburn, Ala., 2006. http://repo.lib.auburn.edu/Send%208-7-07/XU_YINHUI_21.pdf.

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50

Rushing, Jason Clark. "Advancing the Understanding of Water Distribution System Corrosion: Effects of Chlorine and Aluminum on Copper Pitting, Temperature Gradients on Copper Corrosion, and Silica on Iron Release." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34235.

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Abstract:

When severe copper pitting problems impacted customers at a large utility, studies were begun to attempt to diagnose the problem and identify potential solutions. A series of tests were conducted to characterize the nature of pitting. Desktop comparisons of pinhole leak frequency and treatment practices at nearly utilities were also documented to identify treatment factors that might be influencing the initiation and propagation of leaks.

Factors identified included the presence of relatively high levels of free chlorine and aluminum in the distribution system. Experiments were conducted to examine the effect of these constituents on copper pitting under stagnant and flow conditions. That led to discovery of a synergistic redox reaction between chlorine, aluminum solids, and copper metal as evidenced by increased chlorine decay rates, non-uniform corrosion, and rising corrosion potentials.

Temperature changes had been suspected to increase copper pitting frequency and copper release to drinking water. Experiments examined the effect of temperature gradients on copper pipe corrosion during stagnant conditions. The pipe orientation in relation to the temperature gradient determined whether convective mixing would occur, which influenced temperature gradients within the pipe. This work is the first to demonstrate that temperature gradients lead to thermogalvanic currents, influences copper leaching and scale type.

Iron release from corroding water mains is another concern of many water utilities, but little is known about chemistry factors that influence the problem. In laboratory experiments, higher levels of silica caused more iron release to the water and decreased the size of suspended iron particles. Silica levels also changed during the experiment: it decreased through incorporation into a dense scale, and increased by release from cast iron during corrosion. Silica slightly decreased iron corrosion rates near the end of this 6-month test.
Master of Science

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