Zeitschriftenartikel zum Thema „High Oxidation State of Copper“
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1
Kondo, Yasumitsu. „Behaviour of Copper and Nickel during High Temperature Oxidation of Steel Containing Them“. Materials Science Forum 522-523 (August 2006): 53–60. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.53.
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Copper and nickel are accumulated in steels when steel scrap is used as steel sources. It is well known that copper causes hot shortness problem and nickel suppresses the effect of copper. In this paper, the behaviour of copper and nickel during oxidation is investigated. Steels containing copper and nickel were oxidized and the distribution of copper and nickel in the scale was examined. It was found that copper is not only enriched at the scale/metal interface but also exists in upper magnetite layer as a state of solid solution and along grain boundaries of the wustite layer as metal phase. From these results an assumption has been proposed that the liquid copper migrates from the scale/metal interface to the magnetite layer along the grain boundaries. On the other hand, nickel enriched in steel side near the scale/metal interface with copper. The metal particles containing nickel and copper remain inside the scale. Nickel also has an effect of the uneven scale/metal interface formation.
2
Stadt, Michael Georg, Michael Nelhiebel, Silvia Larisegger und Guenter Fafilek. „In-Situ Raman Spectroscopy of Defined Copper Oxide Surfaces Formed by Electrochemically Controlled High-Temperature Oxidation“. ECS Meeting Abstracts MA2023-01, Nr. 46 (28.08.2023): 2490. http://dx.doi.org/10.1149/ma2023-01462490mtgabs.
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The oxidation processes of copper are of great importance since its occurrence leads to various problems, both in further processing and in operation of electronic devices and other technical applications. Extensive research on the thermal oxidation of copper has demonstrated that temperature and oxygen partial pressure affect the formation of oxides, oxidation rates and the chemical composition. In this work powerful electrochemical methods for controlled oxidation are presented, where the oxygen partial pressure on the metal surface can be varied over a range of 10-25 to 100 bar in a single experiment. A specific arrangement of the setup extends its capabilities to enable in-situ Raman spectroscopy measurements of the produced oxide. Controllable oxidation states are achieved in a solid-state electrochemical cell by polarizing a copper sample in contact with a single crystal of yttria-stabilized zirconia, which is conductive for oxygen ions at high temperatures. Optical transparency of the single crystal allows the Raman laser to pass through the crystal to measure the copper oxide formed on the copper-electrolyte interface. Cyclic voltammograms contain kinetic and thermodynamic information about the oxidation processes. Thus, the various oxidation reactions are controlled by the potential that corresponds to the oxygen partial pressure, while the current measures the rate of layer growth as well as the thickness of the oxide layer. In situ Raman measurements allow more detailed analyses of the oxides. The combined data will be used to build a model for oxide layer growth, with particular attention to the defect chemistry of the copper oxide.
3
Anamaria, Imre, Augustin Mot und Radu Silaghi-Dumitrescu. „Exploring the possibility of high-valent copper in models of copper proteins with a three-histidine copper-binding motif“. Open Chemistry 10, Nr. 5 (01.10.2012): 1527–33. http://dx.doi.org/10.2478/s11532-012-0069-3.
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AbstractAn important function of many copper-containing proteins is activation of O2 and subsequent substrate oxidation. The Cu (III) oxidation state is generally considered to be less accessible because of the highly positive Cu (III)/Cu (II) redox potentials with typical amino acid ligands. Here, we employ density functional (DFT) calculations to explore to what extent copper (III) may be accessed in a biologically-relevant coordination environment around a mononuclear copper center, by breaking the oxygen-oxygen bond in a copper-(hydro) peroxide complex. In agreement with previous findings by Solomon and co-workers on copper models with related coordination patterns, the formally high-valent copper complex produced by O-O bond cleavage appears to harbor both oxidizing equivalents on the ligands. The potential energy surface for such a reaction reveals that with the three-histidine binding motif at the copper, O-O bond cleavage is not impossible, but rather disfavored thermodynamically.
4
Bera, J. K., A. G. Samuelson und J. Chandrasekhar. „Structure and energetics of high oxidation state copper fragments: Anab initio study“. Proceedings / Indian Academy of Sciences 108, Nr. 3 (Juni 1996): 333. http://dx.doi.org/10.1007/bf02870100.
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Kowalska, J., und C. S. Gopinath. „Mapping of Copper Oxidation State Using High Pressure X-Ray Photoelectron Spectroscopy“. Acta Physica Polonica A 125, Nr. 4 (April 2014): 1065–66. http://dx.doi.org/10.12693/aphyspola.125.1065.
6
Costa, Gabriel F., Maria Rodrigues Pinto, Igor Messias, Joao Junior, Nirala Singh und Raphael Nagao. „Tracking Copper Oxidation State during Nitrate Electrochemical Reduction Reaction“. ECS Meeting Abstracts MA2023-01, Nr. 39 (28.08.2023): 2300. http://dx.doi.org/10.1149/ma2023-01392300mtgabs.
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The synthesis of ammonia via Haber-Bosch process, obtained from nitrogen catalytic hydrogenation, was a great revolution for humankind that allowed mass production of food with the availability of fertilizers.1 However, it caused a disturbance in the global nitrogen cycle due to the production of ammonia from a non-reactive source (N2), fixing 108 tons of nitrogen into reactive species per year.2 Among nitrogenous contaminants, nitrate is the main pollutant of wastewater and the most oxidized species, being accumulated in the ecosystems.2 Besides that, because of the need of H2 as reactant, the current ammonia production emits 500 million tons of carbon dioxide per year, making ammonia the largest CO2 emitting chemical process.1 Finding sustainable alternatives to restore the nitrogen cycle without compromising ammonia production and consequently food supply is urgently needed.1,3 In this context, nitrate electrochemical reduction reaction (NO3RR) could be a sustainable way to produce ammonia, removing a pollutant from wastewater and helping ammonia decarbonization.2,3 Finding a catalyst that presents high electrochemical performance, high availability, and good stability is still challenging. Among transition metals, copper has the fastest rate-determining step of nitrate reduction to nitrite, offering the highest electrocatalytic kinetics and exchange current densities for NO3RR.4 In addition to metallic copper, its oxides are also attracting attention for catalytic NO3RR.5–13 Different nanomaterials that combine copper metallic and oxide phases have been reported in the literature for ammonia synthesis, with Faradaic efficiencies up to 98%.4 This enhancement is attributed to the fact that Cu2O requires lower activation energy to *NH2O hydrogenation, enabling the faster formation of *NH2OH at catalyst surface.13 Our preliminary results show that there are also synergistic enhancements of Cu and Cu2O, i.e., a prepared mixture of Cu and Cu2O is more active than either compound alone. Herein, we investigate structural and compositional changes at a Cu/Cu2O nanocomposite after and during NO3RR.14 Our findings suggest that under the potentials in which ammonia production from NO3RR takes place, Cu2O is also being reduced to Cu. Figure 1a presents linear sweep voltammetries (LSV) measurements with and without nitrate. LSV obtained in the absence of nitrate (black line) shows a peak related to Cu2O reduction (centered in -0.2 V vs. RHE). In the presence of nitrate (red line), the onset potential is around -0.1 V vs. RHE, from which a cathodic current takes place until -0.8 V vs. RHE. It indicates that Cu2O starts to reduce close to the onset potential for NO3RR. We evaluated the catalyst performance from -0.2 to -0.6 V vs. RHE and the highest faradaic efficiency (66 ± 7%) for NH3 was obtained at -0.4 V vs. RHE (Figure 1b). Then, the composite was ex-situ characterized with spectroscopic and microscopic techniques before and after an 1h-electrolysis at -0.4 V vs. RHE. Though X-ray photoelectron spectroscopy, we show that copper oxidation state changes after potentiostatic electrolysis experiments at -0.4 V vs. RHE (Figures 1c and 1d), where the satellite peak related to Cu2O disappears. Significant structural changes were detected with atomic force microscopy (Figures 1e and 1f), evidenced by the change of the average roughness from 222.5 to 173.1 nm. In-situ Raman spectroscopy was employed to track copper oxidation state during NO3RR. Cu2O has some characteristic peaks at Raman spectra: 150 cm-1 related to infrared active mode F1u (Τ15), 520 cm-1 related to Raman allowed mode 3T’25(F 2g) and 630 cm-1 related to infrared active mode F1u (Τ15).15 The spectra obtained (Figure 1g) showed that these peaks disappear at a less negative potential than the window that ammonia production from NO3RR takes place (-0.2 V vs. RHE), which is in accordance with LSV results, indicating that Cu2O reduces at a more positive potential than nitrate. These results suggest that higher activity for nitrate reduction could be associated with the formation of defects at composite structure, which will be evaluated later with kinetic studies. This work shows strong experimental indicatives that copper oxide is not stable at the potential window employed to ammonia production from NO3RR, although its reduction can induce some defects at copper structure that enhances the catalytic performance. These findings provide important clues towards designing new copper-based materials for electrochemical reduction of nitrate to ammonia. Figure 1
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Zelinka, Samuel L., Grant T. Kirker, George E. Sterbinsky und Keith J. Bourne. „Oxidation states of copper in preservative treated wood as studied by X-ray absorption near edge spectroscopy (XANES)“. PLOS ONE 17, Nr. 1 (27.01.2022): e0263073. http://dx.doi.org/10.1371/journal.pone.0263073.
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Copper is a common component in wood preservatives and is used to protect the wood against fungal degradation. Previous research has shown that the Cu++ oxidation state provides the best wood protection, and Cu++ is widely believed to be the oxidation state of most copper within treated wood. A recent study using X-ray absorption near edge spectroscopy (XANES) reported high amounts of Cu+ in wood that had been in contact with corroded fasteners. This study uses XANES to examine the copper oxidation states in wood treated with several different wood preservatives as a function of time after treatment. In contrast with previous literature which focused on the fixation reaction in the first few hours after treatment, this paper examines the oxidation state of Cu in treated wood at longer times (up to 1-year) after treatment. The results showed in nearly all cases, Cu was in the Cu++ oxidation state to within the measurement uncertainty. Cu XANES patterns taken approximately 1-year after treatment showed no discernable differences between preservative systems, indicating that regardless of the starting treatment the final Cu speciation is the same within one year. The results confirm previously held beliefs about the Cu oxidation states in wood and give further insights into the corrosion mechanism of metals embedded in treated wood.
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Yang, Peng, Xingye Guo, Dingyong He, Zhen Tan, Wei Shao und Hanguang Fu. „Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder“. Metals 11, Nr. 12 (23.11.2021): 1883. http://dx.doi.org/10.3390/met11121883.
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Pure Copper (Cu) is very difficult to prepare using selective laser melting (SLM) technology. This work successfully prepared the pure Cu with high relative density and high strength by the SLM technology using a surface oxidation treatment. The gas-atomized pure Cu powder was used as the feedstock in this work. Before the SLM process, the pure Cu powder was initially handled using the surface oxidation treatment to coat the powder with an extremely thin layer of Cu2O. The SLMed highly dense specimens contain α-Cu and nano-Cu2O phases. A relationship between the processing parameters (laser power (LP), scanning speed (SS), and hatch space (HS)) and density of Cu alloy in SLM was also investigated. The microstructure of SLMed Cu consists of fine grains with grain sizes ranging from 0.5 to ~30 μm. Tensile testing and detailed microstructural characterization were performed on specimens in the as-SLMed and pure copper state specimens. The mechanical property experiments showed that the specimens prepared by SLM technology containing nano-oxide phases had higher yield strength and tensile strength than that of other SLM-built pure copper. However, the elongation was remarkably decreased compared to other SLM-built pure copper, due to the fine grains and the nano-oxides.
9
Uhlmann, Eckart, Julian Polte, Jan Streckenbach, Ngoc Chuong Dinh, Sami Yabroudi, Mitchel Polte und Julian Börnstein. „High-Performance Electro-Discharge Drilling with a Novel Type of Oxidized Tool Electrode“. Journal of Manufacturing and Materials Processing 6, Nr. 5 (01.10.2022): 113. http://dx.doi.org/10.3390/jmmp6050113.
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Electro-discharge drilling is a key technology for manufacturing sophisticated nozzles in a broad range of automotive and aerospace applications. The formation of debris in the working gap leads to arcs and short circuits on the lateral surface when state-of-the-art tool electrodes are used. As a result, limited drilling depth, increased linear tool wear, and the conicity of boreholes are still challenges. In this work, a new approach for the passivation of the lateral surface of copper tool electrodes by oxidation is shown. The comparison with state-of-the-art tool electrodes showed a reduction in the erosion duration by 48% for machining hardened steel. Promising improvements could be achieved by the thermal oxidation of the tool electrodes with the aim of increasing the electrical resistivity of the lateral surface of the tool electrode. However, due to the loss of strength, the high oxide layer thickness, and the partial delamination of the oxide layer, further comprehensive investigations on the influence of the oxidation temperature need to be conducted. Future adjustments with lower oxidation temperatures will be carried out.
10
Loucks, Robert R., Gonzalo J. Henríquez und Marco L. Fiorentini. „Zircon and Whole-Rock Trace Element Indicators of Magmatic Hydration State and Oxidation State Discriminate Copper Ore-Forming from Barren Arc Magmas“. Economic Geology 119, Nr. 3 (01.05.2024): 511–23. http://dx.doi.org/10.5382/econgeo.5071.
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Abstract To meet surging requirements of copper for the green energy revolution, minable resources subequal to all copper production in history must be found in the next two decades. We show that trace elements in zircon and whole-rock samples that are diagnostic of unusually high-pressure magmatic differentiation and high hydration state and oxidation state of their parent silicate melt are effective for discriminating copper sulfide-ore-productive arc magmas from infertile arc magmas. Tests on our database of 5,777 zircons from 80 igneous complexes, including 2,220 zircons from ore-generative intrusions in 37 major porphyry and high-sulfidation epithermal Cu(-Au-Mo) deposits worldwide, demonstrate that our magmatic copper fertility discriminants apparently perform equally well in intraoceanic arcs, continental margin arcs, and continental collision orogens of Ordovician to Quaternary age. That performance consistency means that the tectono-magmatic controls on development of magmatic-hydrothermal copper ore-forming fertility are essentially the same in all those plate-convergence settings. The ratio Ce/√(U × Ti) in zircon is a quantitative indicator of the relative oxygen fugacity of the silicate melt and its sulfur-carrying capacity. The ratio of the europium anomaly to ytterbium in granitoid melts and zircon is an uncalibrated but empirically useful indicator of the melt’s hydration state and ability to provide chloride-complexed metals to exsolving hydrothermal fluids. Plots of (EuN/Eu*)/YbN vs. Ce/√(U × Ti) in zircon are remarkably effective for discriminating igneous complexes, arc segments, and time intervals within them that can generate and are likely to host magmatic-hydrothermal Cu(-Au-Mo) ore deposits. Arrays of cognate zircons on such plots have slopes that vary with pressure-dependent chlorinity of exsolving fluid and its efficacy in scavenging CuCl from the melt. Our zircon indicators of Cu metallogenic fertility are applicable to detrital as well as in situ zircons and can assist with ore discovery in watersheds upstream from a sediment sampling site. We formulated a composite zircon copper fertility index (ZCFI) that can be applied to each microbeam spot analysis—ZCFI = 104 (EuN/EuN*)/YbN + 5 Ce/√(Ui × Ti)—and substantially decreases the number of zircon analyses needed for reliable prospectivity assessment in a detrital grain population, thereby making this watershed-scale exploration tool cost-competitive with other methods of geochemical exploration.
11
Khartaeva, E. Ch, Andrey V. Nomoev, V. V. Syzrantsev, E. L. Dzidziguri, N. S. Khiterkheeva, S. P. Bardakhanov, E. V. Batueva und S. V. Kalashnikov. „Morphology, Sizes and Oxidation of Composite Copper Nanopowders, Obtained by an Electron Beam with Different Energies“. Solid State Phenomena 310 (September 2020): 109–17. http://dx.doi.org/10.4028/www.scientific.net/ssp.310.109.
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Copper nanopowders were obtained by the gas-phase method under the influence of an electron beam of different powers. Thermodynamic modeling of the phase equilibrium state of the Cu-O2-C system during heating in argon and atmospheric pressure was carried out using the TERRA software package. The obtained nanopowders of copper were studied by X-ray phase analysis and transmission electron microscopy. The morphology, structure, size distribution, and average size of copper nanoparticles are determined. The dependence of the content of copper oxides in a copper-containing nanopowder on the electron beam power has been established. It is shown that copper nanopowders obtained at high power are not oxidized.
12
Hussain, Sajid, Eleonora Aneggi, Alessandro Trovarelli und Daniele Goi. „Removal of Organics from Landfill Leachate by Heterogeneous Fenton-like Oxidation over Copper-Based Catalyst“. Catalysts 12, Nr. 3 (16.03.2022): 338. http://dx.doi.org/10.3390/catal12030338.
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Landfill leachates are a mixture of high concentration organic and inorganic contaminants and need to be appropriately treated due to their toxicity and severe adverse effects on the environment. Here, we studied the treatment of landfill leachate through a heterogeneous Fenton-like oxidation process using a zirconia supported copper catalyst (Cu/ZrO2). Reaction conditions such as pH, amount of catalyst, oxidant dose, temperature, and reaction time were investigated and their effects on pollutant abatement discussed. AOS (average oxidation state) and COS (carbon oxidation state) parameters were used for the evaluation of the degree of oxidation of the process, obtaining some insight into the formation of oxidized intermediates (partial oxidation) and the total oxidation (mineralization) of the leachate during the reaction. A two-step oxidation process enhanced the overall performance of the reaction with an abatement of organic compounds of 92% confirming the promising activity of a copper-based catalyst for the treatment of liquid waste. Higher catalytic activity was achieved when the following reaction conditions were applied: 70 °C, pH 5, 200 mg/L of catalyst, 30 mL/L of H2O2 dose, and 150 min. In addition, durability of the catalyst under optimized reaction conditions was verified by repeated reaction cycles.
13
Shu, Min-Fong, und Yi-Hsiu Tseng. „Copper Oxidation Effect in the EMC/Cu Interfacial Adhesion Improvement for a Novel Copper Interconnection Substrate Application“. International Symposium on Microelectronics 2018, Nr. 1 (01.10.2018): 000161–66. http://dx.doi.org/10.4071/2380-4505-2018.1.000161.
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Abstract Copper oxidation structure, cupric oxide (CuO) and cuprous oxide (Cu2O), under Ar/H2 plasma reaction mechanism for the EMC/Cu interface adhesion improvement was studied in this work. This work is utilized TGA to figure out Cu oxidized state and sample preparation, and using plasma treatment Cu oxidation layer to evaluate the EMC/Cu interface adhesion strength by shear testing method. Results show a plasma reduction on Cu oxidation layer provide a better interface adhesion, and the layer structure has a significant composition change, Cu/Cu2O/CuO/EMC → Cu/Cu2O/CuO/Cu2O/EMC. These layer structures were identified by high-resolution TEM mapping with EELS spectrum fitting, it was also verified for CuO reduction to form Cu2O, following the Cu2O hydration would provide much hydrogen-bonding in the EMC/Cu interface. This kind of chain reaction mechanism including CuO reduction and Cu2O hydration was described by 2CuO + H2 → Cu2O +H2O → 2CuOH (hydration molecular). The reaction mechanism of the EMC/Cu bonding has been investigated and verified in this experimental study and our conclusion is that hydrogen bonding on the Cu oxidation layer surface can strengthen the EMC/Cu interface adhesion.
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Zhao, Fengai, Shuanglin Hu, Canhui Xu, Haiyan Xiao, Xiaosong Zhou, Xiaotao Zu und Shuming Peng. „Effect of Copper Doping on Electronic Structure and Optical Absorption of Cd33Se33 Quantum Dots“. Nanomaterials 11, Nr. 10 (28.09.2021): 2531. http://dx.doi.org/10.3390/nano11102531.
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The photophysical properties of Cu-doped CdSe quantum dots (QDs) can be affected by the oxidation state of Cu impurity, but disagreement still exists on the Cu oxidation state (+1 or +2) in these QDs, which is debated and poorly understood for many years. In this work, by using density functional theory (DFT)-based calculations with the Heyd–Scuseria–Ernzerhof (HSE) screened hybrid functional, we clearly demonstrate that the incorporation of Cu dopants into the surface of the magic sized Cd33Se33 QD leads to non-magnetic Cu 3d orbitals distribution and Cu+1 oxidation state, while doping Cu atoms in the core region of QDs can lead to both Cu+1 and Cu+2 oxidation states, depending on the local environment of Cu atoms in the QDs. In addition, it is found that the optical absorption of the Cu-doped Cd33Se33 QD in the visible region is mainly affected by Cu concentration, while the absorption in the infrared regime is closely related to the oxidation state of Cu. The present results enable us to use the doping of Cu impurity in CdSe QDs to achieve special photophysical properties for their applications in high-efficiency photovoltaic devices. The methods used here to resolve the electronic and optical properties of Cu-doped CdSe QDs can be extended to other II-VI semiconductor QDs incorporating transition-metal ions with variable valence.
15
Hao, Yan, Dajie Zhao, Wen Liu, Min Zhang, Yixiao Lou, Zhenzhen Wang, Qinghu Tang und Jinghe Yang. „Uniformly Dispersed Cu Nanoparticles over Mesoporous Silica as a Highly Selective and Recyclable Ethanol Dehydrogenation Catalyst“. Catalysts 12, Nr. 9 (15.09.2022): 1049. http://dx.doi.org/10.3390/catal12091049.
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Selective dehydrogenation of ethanol to acetaldehyde has been considered as an important pathway to produce acetaldehyde due to the atom economy and easy separation of acetaldehyde and hydrogen. Copper catalysts have attracted much attention due to the high activity of Cu species in O-H and C-H bonds oxidative cleavage, and low process cost; however, the size of the Cu nanoparticle is difficult to control since it is easily suffers from metal sintering at high temperatures. In this work, the Cu/KIT-6 catalyst exhibited an ultra-high metal dispersion of 62.3% prepared by an electrostatic adsorption method, due to the advantages of the confinement effect of mesoporous nanostructures and the protective effect of ammonia water on Cu nanoparticles. The existence of an oxidation atmosphere had a significant effect on the valence state of copper species and enhancing moderate acid sites. The catalyst treated by reduction and then oxidation possessed a moderate/weak acid site ratio of ~0.42 and a suitable proportion of Cu+/Cu0 ratio of ~0.53, which conceivably rendered its superior ethanol conversion of 96.8% and full acetaldehyde selectivity at 250 °C. The catalyst also maintained a high selectivity of >99% to acetaldehyde upon time-on-stream of 288 h.
16
Bera, Jitendra K., Ashoka G. Samuelson und Jayaraman Chandrasekhar. „Ab Initio Study of Structures, Energetics, and Bonding in Formally High-Oxidation-State Copper Organometallics“. Organometallics 17, Nr. 19 (September 1998): 4136–45. http://dx.doi.org/10.1021/om980373x.
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Dongbai, Xie, Hong Hao, Duo Shuwang und Li Qiang. „Application on oxidation behavior of metallic copper in fire investigation“. High Temperature Materials and Processes 41, Nr. 1 (01.01.2022): 216–23. http://dx.doi.org/10.1515/htmp-2022-0014.
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Abstract In fire investigations, the most important aspect is determining the presence of a liquid accelerant at the fire scene. The presence or absence of accelerants is critical evidence during trials for fire cases. Upon exposure to high temperatures, metallic substances undergo oxidation, which can be imparted by accelerants in the fire. Oxides and substrates found on metal surfaces offer valuable information on the characteristics of fire, including exposure temperature, duration, and involvement of a liquid accelerant. In this study, we investigated the oxidation behavior of copper at high temperatures in a simulated flame environment using ethanol combustion. After oxidation, the morphological, oxide phase composition, and microstructural features of specimens were characterized by observation, X-ray diffraction, X-ray photoelectron energy spectroscopy, transmission electron microscopy, and scanning electron microscopy with energy-dispersive spectroscopic analysis. The elemental carbon with a hexagonal structure deposited on the sample’s surface was found, which may be incomplete combustion and the chemical composition of ethanol. Copper has a preferred orientation of oxide on the (111) crystal plane, which differs from oxidation in ordinary hot air that is related to the large Coulomb force of the (111) crystal plane. Hot air convection due to combustion may cause large areas of oxide layer on the copper surface to crack and peel. Oxide properties and surface state of metals strongly depended on oxidation duration, temperature, and atmosphere. These data shall offer reference information for determining the presence of combustion accelerants at fire scenes.
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Marik, Sourav, A. J. Dos santos-Garcia, Emilio Morán, O. Toulemonde und M. A. Alario-Franco. „New 1212-Molybdo-Cuprate phases using High pressure and high temperature synthesis“. MRS Advances 1, Nr. 17 (2016): 1215–25. http://dx.doi.org/10.1557/adv.2016.138.
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ABSTRACTNew 1212- type Molybdo-Cuprates of with composition Mo0.5Cu0.5Sr2RECu2O7.5 (RE = Rare Earth) have been prepared by High Pressure and High Temperature (HPHT) synthesis. Their crystal structures are characterized by combining the X-Ray/Neutron powder diffraction and electron diffraction techniques. All the materials show tetragonal symmetry, crystallizing in the P4/mmm space group (S.G.). The chain oxygens are randomly distributed in the two different oxygen sites, which are not completely filled and the defect induced by oxygen vacancies in fact makes the chain fragmented and disordered. The microstructure of these compounds is interpreted by a well-known diagonal cell √2ap × √2ap × 3ap, as confirmed by the Electron diffraction (ED) and transmission electron microscope (TEM). X-ray photoelectron spectroscopy (XPS) studies show the predominance of the non magnetic MoVI state over the MoV one. At the same time oxidation state of copper is found to be dominated by CuII.
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Almutairi, Etab M., Mohamed A. Ghanem, Abdulrahman Al-Warthan, Mufsir Kuniyil und Syed F. Adil. „Hydrazine High-Performance Oxidation and Sensing Using a Copper Oxide Nanosheet Electrocatalyst Prepared via a Foam-Surfactant Dual Template“. Nanomaterials 13, Nr. 1 (26.12.2022): 129. http://dx.doi.org/10.3390/nano13010129.
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This work demonstrates hydrazine electro-oxidation and sensing using an ultrathin copper oxide nanosheet (CuO-NS) architecture prepared via a versatile foam-surfactant dual template (FSDT) approach. CuO-NS was synthesised by chemical deposition of the hexagonal surfactant Brij®58 liquid crystal template containing dissolved copper ions using hydrogen foam that was concurrently generated by a sodium borohydride reducing agent. The physical characterisations of the CuO-NS showed the formation of a two-dimensional (2D) ultrathin nanosheet architecture of crystalline CuO with a specific surface area of ~36 m2/g. The electrochemical CuO-NS oxidation and sensing performance for hydrazine oxidation revealed that the CuO nanosheets had a superior oxidation performance compared with bare-CuO, and the reported state-of-the-art catalysts had a high hydrazine sensitivity of 1.47 mA/cm2 mM, a low detection limit of 15 μM (S/N = 3), and a linear concentration range of up to 45 mM. Moreover, CuO-NS shows considerable potential for the practical use of hydrazine detection in tap and bottled water samples with a good recovery achieved. Furthermore, the foam-surfactant dual template (FSDT) one-pot synthesis approach could be used to produce a wide range of nanomaterials with various compositions and nanoarchitectures at ambient conditions for boosting the electrochemical catalytic reactions.
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DiSpirito, Alan A., Jeremy D. Semrau, J. Colin Murrell, Warren H. Gallagher, Christopher Dennison und Stéphane Vuilleumier. „Methanobactin and the Link between Copper and Bacterial Methane Oxidation“. Microbiology and Molecular Biology Reviews 80, Nr. 2 (16.03.2016): 387–409. http://dx.doi.org/10.1128/mmbr.00058-15.
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SUMMARYMethanobactins (mbs) are low-molecular-mass (<1,200 Da) copper-binding peptides, or chalkophores, produced by many methane-oxidizing bacteria (methanotrophs). These molecules exhibit similarities to certain iron-binding siderophores but are expressed and secreted in response to copper limitation. Structurally, mbs are characterized by a pair of heterocyclic rings with associated thioamide groups that form the copper coordination site. One of the rings is always an oxazolone and the second ring an oxazolone, an imidazolone, or a pyrazinedione moiety. The mb molecule originates from a peptide precursor that undergoes a series of posttranslational modifications, including (i) ring formation, (ii) cleavage of a leader peptide sequence, and (iii) in some cases, addition of a sulfate group. Functionally, mbs represent the extracellular component of a copper acquisition system. Consistent with this role in copper acquisition, mbs have a high affinity for copper ions. Following binding, mbs rapidly reduce Cu2+to Cu1+. In addition to binding copper, mbs will bind most transition metals and near-transition metals and protect the host methanotroph as well as other bacteria from toxic metals. Several other physiological functions have been assigned to mbs, based primarily on their redox and metal-binding properties. In this review, we examine the current state of knowledge of this novel type of metal-binding peptide. We also explore its potential applications, how mbs may alter the bioavailability of multiple metals, and the many roles mbs may play in the physiology of methanotrophs.
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Park, Jun-Han, Jung-Woon Lee, Yong-Won Ma, Bo-Seok Kang, Sung-Moo Hong und Bo-Sung Shin. „Direct Laser Interference Ink Printing Using Copper Metal–Organic Decomposition Ink for Nanofabrication“. Nanomaterials 12, Nr. 3 (25.01.2022): 387. http://dx.doi.org/10.3390/nano12030387.
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In this study, we developed an effective and rapid process for nanoscale ink printing, direct laser interference ink printing (DLIIP), which involves the photothermal reaction of a copper-based metal–organic decomposition ink. A periodically lined copper pattern with a width of 500 nm was printed on a 240 μm-wide line at a fabrication speed of 17 mm/s under an ambient environment and without any pre- or post-processing steps. This pattern had a resistivity of 3.5 μΩ∙cm, and it was found to exhibit a low oxidation state that was twice as high as that of bulk copper. These results demonstrate the feasibility of DLIIP for nanoscale copper printing with fine electrical characteristics.
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Elmas, Sait, Wesley Beelders, Xun Pan und Thomas Nann. „Conducting Copper(I/II)-Metallopolymer for the Electrocatalytic Oxygen Reduction Reaction (ORR) with High Kinetic Current Density“. Polymers 10, Nr. 9 (07.09.2018): 1002. http://dx.doi.org/10.3390/polym10091002.
Annotation:
The oxygen reduction reaction (ORR) is still the most research-intensive aspect of a fuel cell. The sluggish kinetics of the electrocatalysts toward the ORR requires large amounts of platinum to be used as cathode material, which calls for alternatives to replace or minimize the amount of the noble metals used. This study describes the synthesis and complete characterization of a copper metallopolymer (Cu MP) based on a conducting polymer (CP) and single-site catalytic centers for the electrocatalytic ORR. The copper (II) catalyst, embedded in a redox-active and conducting polymeric environment, was pursued as a potential candidate to replace noble metals in fuel cell applications. Performance studies at a rotating disk electrode (RDE) showed that the metallopolymer exhibited a direct four-electron reduction at potentials between −150 and −350 mV vs. the reversible hydrogen electrode (RHE) and high kinetic current densities of over 22.62 mA/cm2. The kinetic current densities obtained at the Cu MP electrode outperformed most of the reported state-of-the art electrocatalysts toward the ORR. Further analysis of the Cu/CP hybrid revealed the copper being largely reduced to the oxidation state +I.
23
Netskina, Olga V., Svetlana A. Mukha, Kirill A. Dmitruk, Arkady V. Ishchenko, Olga A. Bulavchenko, Alena A. Pochtar, Alexey P. Suknev und Oxana V. Komova. „Solvent-Free Method for Nanoparticles Synthesis by Solid-State Combustion Using Tetra(Imidazole)Copper(II) Nitrate“. Inorganics 10, Nr. 2 (21.01.2022): 15. http://dx.doi.org/10.3390/inorganics10020015.
Annotation:
The development of solvent-free techniques for nanoparticles synthesis is one of the challenges of Green chemistry. In this work, the principled opportunity to obtain copper-containing nanosized particles without use of any solvents was shown. The copper complexes were prepared as precursors by the melting-assisted solvent-free synthesis. The formation of tetra(imidazole)copper(II) nitrate complex was confirmed by XRD, elemental analysis, FTIR spectroscopy, and thermal analysis. It was noted that their thermal decomposition occurs in two stages: (I) the low-temperature step may be related to redox interaction between organic ligands and nitrate-anions; (II) the high-temperature step may be related to the oxidation of the products of incomplete imidazole decomposition. TEM and XRD studies of solid products of complex combustion have shown that they are oxides with particle size less than 40 nm. Thus, the combustion of [Cu(Im)4](NO3)2 complex under air can be considered as a new approach to prepare nanosized particles of copper oxides without the use of solvents.
24
Azarapin, Nikita O., Nikolay A. Khritokhin, Victor V. Atuchin, Alexey A. Gubin, Maxim S. Molokeev, Shaibal Mukherjee und Oleg V. Andreev. „Kinetics and Mechanism of BaLaCuS3 Oxidation“. Crystals 13, Nr. 6 (01.06.2023): 903. http://dx.doi.org/10.3390/cryst13060903.
Annotation:
The oxidation reactions of BaLaCuS3 in the artificial air atmosphere were studied at different heating rates in the temperature range of 50–1200 °C. The oxidation stages were determined by DSC-TG, XRD and IR–vis methods. The kinetic characteristics of the proceeding reactions were obtained with the use of the Kissinger model in a linearized form. Compound BaLaCuS3 was stable in the air up to 280 °C. Upon further heating up to 1200 °C, this complex sulfide underwent three main oxidation stages. The first stage is the formation of BaSO4 and CuLaS2. The second stage is the oxidation of CuLaS2 to La2O2SO4 and copper oxides. The third stage is the destruction of La2O2SO4. The final result of the high-temperature treatment in the artificial air atmosphere was a mixture of barium sulfate, copper (II) oxide and La2CuO4. The mechanism and stages of BaLaCuS3 oxidation and further interactions of the components were discussed.
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Leszczyńska-Sejda, Katarzyna, Grzegorz Benke, Joanna Malarz, Mateusz Ciszewski, Dorota Kopyto, Jędrzej Piątek, Michał Drzazga, Patrycja Kowalik, Krzysztof Zemlak und Bartłomiej Kula. „Rhenium(VII) Compounds as Inorganic Precursors for the Synthesis of Organic Reaction Catalysts“. Molecules 24, Nr. 8 (12.04.2019): 1451. http://dx.doi.org/10.3390/molecules24081451.
Annotation:
Rhenium is an element that exhibits a broad range of oxidation states. Synthesis paths of selected rhenium compounds in its seventh oxidation state, which are common precursors for organic reaction catalysts, were presented in this paper. Production technologies for copper perrhenate, aluminum perrhenate as well as the ammonia complex of cobalt perrhenate, are thoroughly described. An ion exchange method, based on Al or Cu metal ion sorption and subsequent elution by aqueous perrhenic acid solutions, was used to obtain perrhenates. The produced solutions were neutralized to afford the targeted aluminum perrhenate and copper perrhenate products in high purity. The developed technologies allow one to manage the wastes from the production of these perrhenates as most streams were recycled. Hexaamminecobalt(III) perrhenate was produced by a newly developed method enabling us to produce a high purity compound in a reaction of spent hexaamminecobalt(III) chloride solution with a perrhenic acid. All prepared compounds are the basis for precursor preparation in organic catalysis.
26
Joska, Luděk, und Miroslav Marek. „Passivation of Dental Amalgams and Mercury Release“. Acta Medica (Hradec Kralove, Czech Republic) 47, Nr. 4 (2004): 243–48. http://dx.doi.org/10.14712/18059694.2018.98.
Annotation:
Objectives: In this study the rate of dissolution of mercury from two dental amalgams with different compositions and structures was determined in vitro under different oxidation and abrasion conditions, and the results were correlated with the electrochemical characteristics. Methods: A spherical high copper and a lathe-cut very high-copper amalgam were tested in aerated and deaerated artificial saliva. The electrochemical characteristics were determined by potential- time, anodic polarization, polarization resistance and cathodic stripping measurements. Mercury release tests were performed after either stabilization in the solution, or abrasion using SiC papers or rotary toothbrush, with or without toothpaste. Dissolved mercury was determined by atomic absorption spectrophotometry. Results: Both amalgams exhibited passivation, the amalgam with the higher copper content passivating spontaneously even when the oxygen content in the solution was minimized. At a higher oxygen content in the solution the rate of mercury release from the amalgams was lower than when the oxygen content was minimized, and decreased further after a pre-exposure. Brushing generally increased the release. Significance: The results show the importance of the oxidation conditions and passivation characteristics of dental amalgams for mercury release, especially in the transient state after abrasion by chewing or tooth brushing.
27
Vagin, V. P., S. S. Manokhin, М. S. Gusakov, Е. V. Surikov, L. S. Yanovsky, D. М. Kondratiev und Yu R. Kolobov. „Study of the evolution of the structural-phase state of W – Cu alloy samples in a graphite shell during vacuum annealing and exposure to high-temperature plasma“. Physics and Chemistry of Materials Treatment 2 (2023): 33–39. http://dx.doi.org/10.30791/0015-3214-2023-2-33-39.
Annotation:
The change in porosity during isothermal vacuum annealing of the pseudo alloy W – 18 wt. % Cu obtained by powder metallurgy methods in the temperature range of 800 – 1200 °C and the resistance to oxidation under the action of high-temperature plasma of the outer surface of a hybrid laboratory structure, consisting of two composite elements made of dissimilar materials: graphite and alloy W – 18 wt. % Cu. The process of evolution of the microstructure controlled by diffusion along the internal interfaces (grain and subgrain boundaries) of copper atoms from copper particles located on these surfaces in the near-surface layers of the sample has been studied.
28
Manesis, Anastasia C., Richard J. Jodts, Brian M. Hoffman und Amy C. Rosenzweig. „Copper binding by a unique family of metalloproteins is dependent on kynurenine formation“. Proceedings of the National Academy of Sciences 118, Nr. 23 (01.06.2021): e2100680118. http://dx.doi.org/10.1073/pnas.2100680118.
Annotation:
Some methane-oxidizing bacteria use the ribosomally synthesized, posttranslationally modified natural product methanobactin (Mbn) to acquire copper for their primary metabolic enzyme, particulate methane monooxygenase. The operons encoding the machinery to biosynthesize and transport Mbns typically include genes for two proteins, MbnH and MbnP, which are also found as a pair in other genomic contexts related to copper homeostasis. While the MbnH protein, a member of the bacterial diheme cytochrome c peroxidase (bCcP)/MauG superfamily, has been characterized, the structure and function of MbnP, the relationship between the two proteins, and their role in copper homeostasis remain unclear. Biochemical characterization of MbnP from the methanotroph Methylosinus trichosporium OB3b now reveals that MbnP binds a single copper ion, present in the +1 oxidation state, with high affinity. Copper binding to MbnP in vivo is dependent on oxidation of the first tryptophan in a conserved WxW motif to a kynurenine, a transformation that occurs through an interaction of MbnH with MbnP. The 2.04-Å-resolution crystal structure of MbnP reveals a unique fold and an unusual copper-binding site involving a histidine, a methionine, a solvent ligand, and the kynurenine. Although the kynurenine residue may not serve as a CuI primary-sphere ligand, being positioned ∼2.9 Å away from the CuI ion, its presence is required for copper binding. Genomic neighborhood analysis indicates that MbnP proteins, and by extension kynurenine-containing copper sites, are widespread and may play diverse roles in microbial copper homeostasis.
29
Nechvoglod, Olga V., und Alena G. Upolovnikova. „The study of the phase composition of the products of electrochemical oxidation of sulfide granules of the system Cu1.96S–Ni3S2–Cu–Ni“. Butlerov Communications 57, Nr. 3 (31.03.2019): 149–54. http://dx.doi.org/10.37952/roi-jbc-01/19-57-3-149.
Annotation:
The crystallization rate of copper and nickel sulfides influences on the phase formation processes. The high crystallization rate (about 103 degrees/s), achieved through granulation of the sulfide copper-nickel melt, leads to the stabilization of non-stoichiometric phases, the formation of ultrafine structures, which are grains and partial dissolution of the metal component in the sulfide. The structure of the granules is formed by nickel sulfide (Cu1.96S) phases in the form of dendritic inclusions of 2-20 µm in size in the nickel sulfide phase (Ni3S2). According to the phase diagram of the state of Cu – Ni – S, a solid solution of Cu – Ni may be present in the composition of eutectic compounds with copper and nickel sulphides. The electrochemical oxidation of copper and nickel sulfides in a solution of sulfuric acid occurs through a series of successive phase transformations described in the work, during which the conversion of sulfides occurs in intermediate oxidation states oxidizing to the elemental state: Cu1.96S → Cu1.8S → Cu1.75S → CuS → S; Ni3S2 → NiS → S. The non-stoichiometric composition of compounds suggests the presence of excessive or deficient sulfur and metal contents in the crystal lattice, which can affect the mechanism and sequence of phase transformations during the electrochemical oxidation of sulfide granules. Dissolution occurs not only on the surface of the granules, but also along the grain boundaries. The leached areas form capillaries inside the granules, through which electrolyte enters the electrochemical reactions. Porous sulfur sulfide sludge forms on the surface of the granules. The phase composition of the sludge was studied. The main phase components of poorly soluble products are nickel granules Ni3+хS2–Cu2-хS.
30
Peng, Zaihua, Xinzhuang Fu, Zujiang Pan, Ya Gao, Dongdong He, Xiaohui Fan, Tong Yue und Wei Sun. „Efficient Recovery of the Combined Copper Resources from Copper Oxide Bearing Limonite Ore by Magnetic Separation and Leaching Technology“. Minerals 12, Nr. 10 (04.10.2022): 1258. http://dx.doi.org/10.3390/min12101258.
Annotation:
The reserve of the copper-oxide-bearing limonite ore (COBL ore) in Yulong Copper Co., Ltd. is up to 20 million tons with 1.79% of copper content. The characters of the copper resources in the COBL ore are high-proportioned oxidation state (99.98%) and combined state (84.83%). The combined copper oxide is mainly copper-oxide-bearing limonite, which has a copper content of more than 78%. Because of the high altitude and average annual temperature of 15 °C in Tibet, fire leaching cannot be adopted. The leaching efficiency of copper from COBL ore using direct leaching of sulfuric acid is only 40%, which is greatly influenced by temperature and time. Based on the characteristics of COBL ore, a novel combined method of magnetic separation and individual leaching has been proposed to efficient recover copper resources. Experimental results show that the magnetic concentrates and tailings were obtained by magnetic separation of COBL ore at 0.6 T with the yields were 59.65% and 40.35%, respectively. Due to the obvious leaching properties difference of the magnetic concentrates and tailings, individual leaching process routes were used to treat them. The magnetic concentrate was leached with stirring for 3 days at room temperature (20 °C), and the magnetic tailing was easily leached for 4 h at 40 °C. The recovery efficiency of total copper was 72%, which was about 32% higher than that of the single leaching of the COBL ore. The method proposed in this study achieves environmentally friendly, low energy consumption, and efficient extraction of refractory copper oxide ore.
31
Tang, Ming, Cin-Ty A. Lee, Wei-Qiang Ji, Rui Wang und Gelu Costin. „Crustal thickening and endogenic oxidation of magmatic sulfur“. Science Advances 6, Nr. 31 (Juli 2020): eaba6342. http://dx.doi.org/10.1126/sciadv.aba6342.
Annotation:
Porphyry ore deposits, Earth’s most important resources of copper, molybdenum, and rhenium, are strongly associated with felsic magmas showing signs of high-pressure differentiation and are usually found in places with thickened crust (>45 kilometers). This pattern is well-known, but unexplained, and remains an outstanding problem in our understanding of porphyry ore deposit formation. We approach this problem by investigating the oxidation state of magmatic sulfur, which controls the behavior of ore-forming metals during magma differentiation and magmatic-hydrothermal transition. We use sulfur in apatite to reconstruct the sulfur oxidation state in the Gangdese batholith, southern Tibet. We find that magma sulfate content increased abruptly after India-Eurasia collision. Apatite sulfur content and the calculated magma S6+/ΣS ratio correlate with whole-rock dysprosium/ytterbium ratio, suggesting that residual garnet, favored in thickened crust, exerts a first-order control on sulfur oxidation in magmatic orogens. Our findings link sulfur oxidation to internal petrogenic processes and imply an intrinsic relationship of magma oxidation with synmagmatic crustal thickening.
32
Nechvoglod, O. V., Evgeny N. Selivanov und S. V. Mamyachenkov. „Effect of Structure on the Electrochemical Oxidation Rate of Copper and Nickel Sulfides“. Defect and Diffusion Forum 326-328 (April 2012): 383–87. http://dx.doi.org/10.4028/www.scientific.net/ddf.326-328.383.
Annotation:
Synthesized samples were crystallized at 10 - 1000 K/sec (νcooling) to study the effect of sulfides structure on the electrochemical oxidation rates. The methods of X-ray, optical and electronic microscopy are used to analyze the phase composition, and the methods of voltamperometry and chronoamperometry are used to study the laws of electrochemical oxidation. Slow cooling of the samples with sulfide phase (Cu1,96S, Ni3S2) leads to crystallization of the metal (Ni, Cu). High cooling rate leads to crystallization of non-equilibrium phases, increasing of proportion of the sulfide phase and decreasing of metallic component up to complete disappearance. It is shown that electrochemical oxidation of copper and nickel sulfides proceeds stepwise: Me2S Me2-XS Me1+XS MeS Me2+ + S. Experiments have revealed the rates of electrochemical oxidation of granular sulfides that exceed the rates established for the slowly cooled samples. The rates of the electrochemical oxidation of Ni3S2 at potential of 1500 mV are 8.810-8 g/sec·mm2 (at vcooling = 10 К/sec) and 1.310-7 g/sec·mm2 (at νcooling = 1000 К/sec). The rates of the electrochemical oxidation of Cu2S at potential of 1000 mV are 2.810-8 g/sec·mm2 (at νcooling = 10 К/sec) and 4.310-8 g/sec·mm2 (at νcooling = 1000 К/sec). It is found that the forming of a passivation layer effects the rate of the electrochemical oxidation of copper sulfide and nickel sulfide. Non-equilibrium phase composition and refinement provide greater reactivity of sulfides in the conditions of anodic polarization. The oxidation and passivation of metallic phase along with sulfide phases proceed from the surface of Me2S Me alloys. As for the samples crystallized at 1000 K/sec only anodic oxidation of sulfides occurs due to a lack of metallic phase. The compositions of passivation films and potentials providing the extraction of sulfur in the elemental state from the sulfides crystallized at high rates were determined.
33
Özçelik, Seda, und Zafir Ekmekçi. „Reducing Negative Effects of Oxidation on Flotation of Complex Cu–Zn Sulfide Ores“. Minerals 12, Nr. 8 (12.08.2022): 1016. http://dx.doi.org/10.3390/min12081016.
Annotation:
Surface oxidation of the sulfide minerals negatively affects the flotation performance, i.e., the selectivity and even the recoveries at heavy oxidation conditions. Oxidation may take place during the formation of the ore, during mining and stockpiling, and during the flotation process. Stockpiling of large amounts of ore is a common practice in mine sites for blending the process–plant feed. However, a long stockpiling time may cause severe surface oxidation of the complex sulfide ores, particularly the complex Cu–Zn sulfide ores containing secondary copper minerals, which resulted in loss of Cu–Zn selectivity and copper recovery. A complex Cu–Zn sulfide ore was used to investigate effects of stockpile time on flotation performance and to determine the most efficient mitigation method to restore the flotation performance. Batch-scale flotation tests were performed on a heavily oxidized sample using sulfidization, high intensity conditioning, and their combination. The results showed that sulfidization desliming and stage addition of depressants during flotation was the most effective method for producing a copper concentrate from oxidized ores.
34
Allam, Djaouida, Salem Cheknoun und Smain Hocine. „Operating Conditions and Composition Effect on the Hydrogenation of Carbon Dioxide Performed over CuO/ZnO/Al2O3 Catalysts“. Bulletin of Chemical Reaction Engineering & Catalysis 14, Nr. 3 (01.12.2019): 604. http://dx.doi.org/10.9767/bcrec.14.3.3451.604-613.
Annotation:
A series of catalysts constituted of mixed copper and zinc oxides supported on alumina were prepared by co-precipitation method. The cooper content was in the 10-90 wt.% range. Their catalytic behavior in the hydrogenation of carbon dioxide to methanol was investigated at high pressure (up to 75 bars). The catalysts were characterized by elemental analysis, N2-adsorption, N2O-chemisorptions, and X-ray diffraction (XRD). The catalysts showed a clear activity in the hydrogenation reaction that could be correlated to the surface area of the metallic copper and to the reaction pressure. The CuO/ZnO/Al2O3 catalyst with a Cu/Zn/Al weight ratio of 60/30/10, exhibits the highest carbon dioxide conversion and methanol selectivity. Finally, a mechanism pathway has been proposed on copper active sites of (Cu0/CuI) oxidation state. Copyright © 2019 BCREC Group. All rights reserved
35
Fomenko, Varvara I., Arina V. Murashkina, Alexei D. Averin, Anastasiya A. Shesterkina und Irina P. Beletskaya. „Unsupported Copper Nanoparticles in the Arylation of Amines“. Catalysts 13, Nr. 2 (02.02.2023): 331. http://dx.doi.org/10.3390/catal13020331.
Annotation:
Commercially available copper and copper (II) oxide nanoparticles (CuNPs and CuO NPs) were characterized using TEM and electronography methods to elucidate their true average size and composition. The catalytic amine arylation using unsupported copper nanoparticles differing in their size and copper oxidation state was investigated. The reaction of the model iodobenzene with n-octylamine was shown to be successfully catalyzed by CuNPs of average size 25 and 10/80 nm in the presence of the ligands such as 2-isobutyrylcyclohexanone (L1) and rac-1,1′-bi-2-naphthol (BINOL, L2), giving high yields (up to 95%) of the target N-octylaniline. CuO in bulk and nano forms was shown to be almost equally efficient in this process. Studies on the Cu-catalyzed amination of substituted iodobenzenes and 2-iodopyridine, as well as the arylation of different aliphatic amines and NH-heterocycles, verified that CuNPs (25 or 10/80 nm) with L1 and L2 are the most versatile and efficient nanocatalysts for a variety of substrates. Investigation of copper leaching under different conditions was carried out.
36
Chung, Clive Yik-Sham, Jessica M. Posimo, Sumin Lee, Tiffany Tsang, Julianne M. Davis, Donita C. Brady und Christopher J. Chang. „Activity-based ratiometric FRET probe reveals oncogene-driven changes in labile copper pools induced by altered glutathione metabolism“. Proceedings of the National Academy of Sciences 116, Nr. 37 (26.08.2019): 18285–94. http://dx.doi.org/10.1073/pnas.1904610116.
Annotation:
Copper is essential for life, and beyond its well-established ability to serve as a tightly bound, redox-active active site cofactor for enzyme function, emerging data suggest that cellular copper also exists in labile pools, defined as loosely bound to low-molecular-weight ligands, which can regulate diverse transition metal signaling processes spanning neural communication and olfaction, lipolysis, rest–activity cycles, and kinase pathways critical for oncogenic signaling. To help decipher this growing biology, we report a first-generation ratiometric fluorescence resonance energy transfer (FRET) copper probe, FCP-1, for activity-based sensing of labile Cu(I) pools in live cells. FCP-1 links fluorescein and rhodamine dyes through a Tris[(2-pyridyl)methyl]amine bridge. Bioinspired Cu(I)-induced oxidative cleavage decreases FRET between fluorescein donor and rhodamine acceptor. FCP-1 responds to Cu(I) with high metal selectivity and oxidation-state specificity and facilitates ratiometric measurements that minimize potential interferences arising from variations in sample thickness, dye concentration, and light intensity. FCP-1 enables imaging of dynamic changes in labile Cu(I) pools in live cells in response to copper supplementation/depletion, differential expression of the copper importer CTR1, and redox stress induced by manipulating intracellular glutathione levels and reduced/oxidized glutathione (GSH/GSSG) ratios. FCP-1 imaging reveals a labile Cu(I) deficiency induced by oncogene-driven cellular transformation that promotes fluctuations in glutathione metabolism, where lower GSH/GSSG ratios decrease labile Cu(I) availability without affecting total copper levels. By connecting copper dysregulation and glutathione stress in cancer, this work provides a valuable starting point to study broader cross-talk between metal and redox pathways in health and disease with activity-based probes.
37
Bharadwaj, Mridula D., Lori Tropia, Murray Gibson und Judith C. Yang. „Initial Kinetics of Copper Oxidation in Different Oxidizing Atmospheres as Studied by In Situ UHV-TEM“. Microscopy and Microanalysis 6, S2 (August 2000): 42–43. http://dx.doi.org/10.1017/s1431927600032700.
Annotation:
It is of fundamental and practical interest to understand the oxidation process since a desirable property for metals is resistance to corrosion. But there is a wide gap between information provided by surface science methods and that provided by bulk oxidation studies. The former have mainly examined the adsorption of ∼ 1 ML of oxygen on the metal surface, where as both low and high temperature bulk oxidation studies have mainly focused on the growth of an oxide layer at the later stages of oxidation.We are probing the initial oxidation stage of a model metal system by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM) in order to gain insights into the initial kinetics of oxidation. We have previously shown that the growth mechanism of the cuprous oxide is initially dominated by oxygen surface diffision.
38
Yamauchi, Hisao, und Maarit Karppinen. „Application of high-pressure techniques: stabilization and oxidation-state control of novel superconductive and related multi-layered copper oxides“. Superconductor Science and Technology 13, Nr. 4 (29.03.2000): R33—R52. http://dx.doi.org/10.1088/0953-2048/13/4/202.
39
Kuo, Yue. „(Invited) Plasma-Based Thin Film Technology in Fabrication of Nano- to Giga-Sized Electronics“. ECS Meeting Abstracts MA2022-02, Nr. 30 (09.10.2022): 1106. http://dx.doi.org/10.1149/ma2022-02301106mtgabs.
Annotation:
This talk is presented to honor Professor Noel Buckley who has made many important contributions in compound semiconductors, copper thin film deposition, batteries, and other topics critical to the manufacture of modern optoelectronics. He is also a good friend, colleague, and collaborator for 3 decades. Plasma technology has been broadly used in the mass production of modern electronics varying from nano-sized devices in ICs to giga-dimension flat panel displays. It is especially critical to the preparation of thin films with well-controlled properties, geometry, and reliability. In this talk, the speaker shall discuss the recent development of plasma thin film deposition, etching, and reaction in his laboratory for the manufacture of electronic and optoelectronic products. Room-temperature plasma-based copper etch processes for sub 0.5 μm geometry patterns ICs and large-area direct-view TFT LCDs Sputter deposited sub 1 nm EOT high-k gate dielectrics, nanocrystals embedded high-k dielectric nonvolatile memories, and solid-state incandescent light emitting devices (SSI-LEDs) Plasma oxidation of copper as a self-aligned passivation film
40
Cesselin, Bénédicte, Djae Ali, Jean-Jacques Gratadoux, Philippe Gaudu, Patrick Duwat, Alexandra Gruss und Meriem El Karoui. „Inactivation of the Lactococcus lactis high-affinity phosphate transporter confers oxygen and thiol resistance and alters metal homeostasis“. Microbiology 155, Nr. 7 (01.07.2009): 2274–81. http://dx.doi.org/10.1099/mic.0.027797-0.
Annotation:
Numerous strategies allowing bacteria to detect and respond to oxidative conditions depend on the cell redox state. Here we examined the ability of Lactococcus lactis to survive aerobically in the presence of the reducing agent dithiothreitol (DTT), which would be expected to modify the cell redox state and disable the oxidative stress response. DTT inhibited L. lactis growth at 37 °C in aerobic conditions, but not in anaerobiosis. Mutants selected as DTT resistant all mapped to the pstFEDCBA locus, encoding a high-affinity phosphate transporter. Transcription of pstFEDCBA and a downstream putative regulator of stress response, phoU, was deregulated in a pstA strain, but amounts of major oxidative stress proteins were unchanged. As metals participate in oxygen radical formation, we compared metal sensitivity of wild-type and pstA strains. The pstA mutant showed approximately 100-fold increased resistance to copper and zinc. Furthermore, copper or zinc addition exacerbated the sensitivity of a wild-type L. lactis strain to DTT. Inactivation of pstA conferred a more general resistance to oxidative stress, alleviating the oxygen- and thermo-sensitivity of a clpP mutant. This study establishes a role for the pst locus in metal homeostasis, suggesting that pst inactivation lowers intracellular reactivity of copper and zinc, which would limit bacterial sensitivity to oxygen.
41
Davies, P. K., und C. M. Katzan. „Oxidation, reduction, and stability of the BaLa4Cu5O13±δ system“. Proceedings, annual meeting, Electron Microscopy Society of America 47 (06.08.1989): 162–63. http://dx.doi.org/10.1017/s0424820100152781.
Annotation:
The electronic and structural properties of most of the high temperature superconducting copper oxides are highly dependent upon the oxidation conditions used to prepare the cuprate compounds. Until recently superconductivity had only been observed in highly oxidized compounds, however recent work has shown that under certain circumstances superconducting transitions can also occur in n-doped, reduced cuprates. In an effort to understand some of the chemical factors that lead to the stabilization of both oxidized and reduced cuprates, we have investigated the stability of several cuprates. In this paper we report our results on the metallic, non-superconducting BaLa4Cu5O13±δ (“145”) system.At high temperature most of the highly oxidized cuprates are reduced as oxygen is reversibly removed from the perovskite lattice and the Cu valence is lowered to ≤ 2. However, for compounds with the 145 stoichiometry there is no significant oxygen loss in “non-reactive” gases such as air, O2 or He, and even at 1000°C Cu is apparently stable in a valence state greater than 2.3+.
42
Mukherjee, Subham, Gayetri Sarkar, Abhranil De und Bhaskar Biswas. „A square planar copper(II) complex noncovalently conjugated with a p-cresol for bioinspired catecholase activity“. European Journal of Chemistry 14, Nr. 4 (31.12.2023): 499–506. http://dx.doi.org/10.5155/eurjchem.14.4.499-506.2489.
Annotation:
This work presents the synthesis of an unprecedented p-cresol-conjugated copper(II) complex as a p-cresol-coupled polydentate ligand, its crystal structure, and catecholase activity. X-ray crystallography reveals that the Cu(II) centre adopts a nearly planar coordination geometry. Crystal data for C14H13Cu0.5O3: Monoclinic, space group P21/c (no. 14), a = 5.9204(2) Å, b = 21.5615(10) Å, c = 9.0715(4) Å, β = 91.266(4)°, V = 1157.72(8) Å3, Z = 4, μ(MoKα) = 0.987 mm-1, Dcalc = 1.498 g/cm3, 12647 reflections measured (6.884° ≤ 2Θ ≤ 63.42°), 3233 unique (Rint = 0.0618, Rsigma = 0.0512) which were used in all calculations. The final R1 was 0.0710 (I > 2σ(I)) and wR2 was 0.2173 (all data). The crystallized p-cresol was localized in complex units through intermolecular O···H interactions and formed a 3D supramolecular framework employing short-ranged O···H and C-H···π interactions in the solid state. The copper(II) complex has been evaluated as a bioinspired catalyst in the oxidative transformation of 3,5-di-tert-butylcatechol (DTBC) to o-benzoquinone in acetonitrile with a high turnover number, 2.26´104 h–1. Electrochemical analysis of the copper(II) complex in the presence of DTBC recommends the generation of a catechol/o-benzosemiquinone redox couple during catalytic oxidation with the generation of hydrogen peroxide as a byproduct.
43
Hu, Liangxing, Simon Chun Kiat Goh, Jing Tao, Yu Dian Lim, Peng Zhao, Michael Joo Zhong Lim, Teddy Salim, Uvarajan M. Velayutham und Chuan Seng Tan. „Time-Dependent Evolution Study of Ar/N2 Plasma-Activated Cu Surface for Enabling Two-Step Cu-Cu Direct Bonding in a Non-Vacuum Environment“. ECS Journal of Solid State Science and Technology 10, Nr. 12 (01.12.2021): 124001. http://dx.doi.org/10.1149/2162-8777/ac3b8e.
Annotation:
In this paper, a two-step copper-copper direct bonding process in a non-vacuum environment is reported. Time-dependent evolution of argon/nitrogen plasma-activated copper surface is carefully studied. A multitude of surface characterizations are performed to investigate the evolution of the copper surface, with and without argon/nitrogen plasma treatment, when it is exposed to the cleanroom ambient for a period of time. The results reveal that a thin layer of copper nitride is formed upon argon/nitrogen plasma activation on copper surface. It is hypothesized that the nitride layer could dampen surface oxidation. This allows the surface to remain in an “activated” state for up to 6 h. Afterwards, the activated dies are physically bonded at room temperature in cleanroom ambient. Thereafter, the bonded dies are annealed at 300 °C for varying duration, which results in an improvement of the bond strength by a factor of 70∼140 times. A sample bonded after plasma activation and 2-h cleanroom ambient exposure demonstrates the largest shear strength (∼5 MPa). The degradation of copper nitride layer at elevated temperature could aid in maintaining a localized inert environment for the initial diffusion of copper atoms across the interface. This novel bonding technique would be useful for high-throughput three-dimensional wafer bonding and heterogeneous packaging in semiconductor manufacturing.
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Karimov, Kirill, Oleg Dizer, Maksim Tretiak und Denis Rogozhnikov. „Purification of Copper Concentrate from Arsenic under Autoclave Conditions“. Metals 14, Nr. 2 (25.01.2024): 150. http://dx.doi.org/10.3390/met14020150.
Annotation:
This study presents the results of a two-stage autoclave processing of a copper–arsenic concentrate. Copper concentrate is an important raw material to produce copper and other metals. However, in some cases, the concentrate may contain increased amounts of arsenic, which makes further processing difficult. Therefore, the development of modern hydrometallurgical methods for processing copper concentrate with a high arsenic content is an urgent task, which could lead to the optimization of the raw material processing process and the improvement of the quality of the concentrate. It has been established that the optimal conditions for the sequential two-stage autoclave processing of copper–arsenic concentrate are: t = 220–225 °C, τoxidation = 20 min, τtot = 90 min, Po2 = 0.4 MPa, and L:S = 10:1, [H2SO4]initial = 40 g/dm3; in this case, 85% of zinc, 44% of iron, and 78% of arsenic, respectively, are extracted into the solution during both stages and the loss of copper was about 0.01%. This is explained by the fact that at the first stage (oxidation) of the autoclave processing of the copper–arsenic concentrate, copper, together with iron, leaches into the solution, and at the second stage (reduction), copper precipitates out of the solution in the form of chalcocite. Copper in the residue after autoclave leaching is in the form of Cu2S, iron is in the form of pyrite (FeS2), and lead is in the form of anglesite (PbSO4), respectively. The obtained micrographs and EDX mappings clearly show no iron arsenates. This confirms that at the oxidative stage of the developed process, arsenic, removed by 78%, remains in the solution. The remaining arsenic is associated with tennantite, indicating the effectiveness of the treatment process in removing arsenic from the copper–arsenic concentrate. A second important observation is the presence of pronounced areas of copper sulfides in the microphotos without iron and arsenic impurities. This confirms that copper is deposited as chalcocite during the reduction phase of the process, which is the desired result.
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Carlesi, Carlos, Robert C. Harris, Andrew P. Abbott und Gawen R. T. Jenkin. „Chemical Dissolution of Chalcopyrite Concentrate in Choline Chloride Ethylene Glycol Deep Eutectic Solvent“. Minerals 12, Nr. 1 (05.01.2022): 65. http://dx.doi.org/10.3390/min12010065.
Annotation:
Currently, the high demand for copper is in direct contrast with the decrease in the mineral grade and, more significantly, the concerns regarding the environmental impact that arise as a result of processing such low-grade materials. Consequently, new mineral processing concepts are needed. This work explores the chemical dissolution of chalcopyrite concentrate at ambient pressure and moderate temperatures in a deep eutectic solvent. Copper and iron are dissolved without changing their oxidation state, without solvent pH change, and stabilized as a chloride complex with no evidence of passivation. Chemical equilibria of the metallic chloride complexes limit the dissolution, and the step that is rate-controlling of the kinetics is the interdiffusion of species in the solvent. The chemical mechanism may involve initial chloride adsorption at positive sites of the solid surface, pointing out the importance of surfaces states on chalcopyrite particles. A model based on a shrinking particle coupled with pseudo-second-order increase in the liquid concentration of copper describes the dissolution kinetics and demonstrates the importance of the liquid to solid ratio. Iron and copper can be recovered separately from the solvent, which highlights that this concept is an interesting alternative to both redox-hydrometallurgy and pyrometallurgy to obtain copper by the processing of chalcopyrite concentrate.
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Anand, Vijay Kumar, Kapil Bhatt, Sandeep Kumar, B. Archana, Sandeep Sharma, Karamvir Singh, Monish Gupta, Rakesh Goyal und G. S. Virdi. „Sensitive and Enzyme-Free Glucose Sensor Based on Copper Nanowires/Polyaniline/Reduced Graphene Oxide Nanocomposite Ink“. International Journal of Nanoscience 20, Nr. 02 (10.03.2021): 2150020. http://dx.doi.org/10.1142/s0219581x21500204.
Annotation:
In this paper, we report the preparation and characterization of a sensitive and reusable nonenzymatic glucose (NEG) sensor based on copper nanowires (CuNWs)/polyaniline (PANI)/reduced graphene oxide (rGO) nanocomposite ink. The CuNWs/PANI/rGO nanocomposite ink was prepared by solvothermal mixing of CuNWs, PANI, rGO and binders. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier Transform Infra-Red (FT-IR) spectroscopy techniques were used to assess the structural and morphological parameters of prepared nanocomposite ink. The cyclic voltammetry (CV) technique was used to estimate the electrochemical behavior of prepared NEG sensor. The structural, morphological and spectroscopy results confirmed the change in morphological and oxidation state of CuNWs to CuO nanostructures as a constituent of nanocomposite ink. The CuO nanostructures supported on PANI/rGO demonstrated good electrochemical stability and great electrocatalytic activity toward glucose oxidation. At a glucose oxidation potential of 0.64V, the prepared NEG sensor exhibited great electrocatalytic ability by offering a high sensitivity of 843.06[Formula: see text]AmM[Formula: see text]cm[Formula: see text] in the linear glucose range 0–4mM with a lower detection limit of 1.6mM. In addition to these outstanding performance characteristics, CuNWs/PANI/rGO nanocomposite ink-based NEG sensor has the advantages of ease of fabrication, low cost and reusability.
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Cocic, Mira, Mihovil Logar, Sasa Cocic, Dragana Zivkovic, Branko Matovic und Snezana Devic. „Determination of sulphide concentrates of ore copper by XRPD and chemical analysis“. Chemical Industry 63, Nr. 4 (2009): 319–24. http://dx.doi.org/10.2298/hemind0904319c.
Annotation:
Roasting process of sulphide copper concentrates in fluo-solid reactor is an oxidation process, and presents the first stage of copper concentrate processing in Copper Mining and Smelting Complex Bor, RTB Bor. Therefore, the importance of accurate and up to date process control is an apparent precondition for the correct treatment in the following stages and also for of high grade cathode copper. As concentrate is fed into the roaster, it is heated by a stream of hot air to about 590?C. The process takes place between solid and gaseous phases without the appearance of a liquid phase. The heat generated by the exothermic oxidation reaction of sulphur from cooper and iron minerals (chalcopyrite and pyrite) is sufficient to carry out the entire process autogenously at temperature from 620 to 670?C. The temperature of sulphur firing which defines the start of roasting depends on physical traits, particle size of sulfides and characteristic product of oxidation. The obtained products of the roasting process are: calcine, ready for smelting in the furnace and gas-rich sulphure dioxide (SO2), well suited for the production of sulfuric acid. The relationship between the quantitative mineral composition of the charge and of the calcine directly points out to the efficiency of the roasting process in fluo-solid reactor. The amount of bornite and magnetite, resulting from the sulfide oxidation is the most important parameter. Hence, quantitative determination of mineral composition is of great interest. In this work, the results of the determination of quantitative mineral composition of the copper sulphide concentrate (charge) and products of their roasting (calcine and overflow) in fluo-solid reactor in the RTB Bor are presented. The aim was to compare the results of the iron, copper, sulfur and oxygen contents determined by two independent techniques, the chemical (HA) and X-ray powder diffraction analysis (XRPD) that is based on the quantitative mineral composition. Differences in the obtained results are evident, but small enough to confirm the reliability of measurement.
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Armendariz, Angela D., Mauricio Gonzalez, Alexander V. Loguinov und Christopher D. Vulpe. „Gene expression profiling in chronic copper overload reveals upregulation of Prnp and App“. Physiological Genomics 20, Nr. 1 (15.12.2004): 45–54. http://dx.doi.org/10.1152/physiolgenomics.00196.2003.
Annotation:
The level at which copper becomes toxic is not clear. Several studies have indicated that copper causes oxidative stress; however, most have tested very high levels of copper exposure. We currently have only a limited understanding of the protective systems that operate in cells chronically exposed to copper. Additionally, the limits of homeostatic regulation are not known, making it difficult to define the milder effects of copper excess. Furthermore, a robust assay to facilitate the diagnosis of copper excess and to distinguish mild, moderate, and severe copper overload is needed. To address these issues, we have investigated the effects on steady-state gene expression of chronic copper overload in a cell culture model system using cDNA microarrays. For this study we utilized cells from genetic models of copper overload: fibroblast cells from two mouse mutants, C57BL/6- Atp7aMobr and C57BL/6- Atp7aModap. These cell lines accumulate copper to abnormally high levels in normal culture media due to a defect in copper export from the cell. We identified 12 differentially expressed genes in common using our outlier identification methods. Surprisingly, our results show no evidence of oxidative stress in the copper-loaded cells. In addition, candidate components perhaps responsible for a copper-specific homeostatic response are identified. The genes that encode for the prion protein and the amyloid-β precursor protein, two known copper-binding proteins, are upregulated in both cell lines.
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Simakov, S. V., N. A. Vinogradova, A. A. Ashmarin, A. B. Mikhajlova, O. N. Nikitushkina, E. E. Starostin und V. I. Tovtin. „Effect of plastic deformation, heat treatment and electron irradiation on structural-phase state of Cu – 40 аt. % Pd alloy“. Physics and Chemistry of Materials Treatment 6 (2022): 11–16. http://dx.doi.org/10.30791/0015-3214-2022-6-11-16.
Annotation:
Effect of plastic deformation, heat treatment, and electron irradiation on the structural-phase state of Cu – 40 at. % Pd is studied. X-ray phase analysis of initial samples, samples obtained by rolling up to 0.2 mm, samples annealed after rolling in an argon atmosphere at 950 °C for 1 h, and samples irradiated by high-energy electron in air at temperature of 300 °C was carried out. A change in the phase composition of the samples after rolling was found: ~ 6 % of the ordered β-phase with bcc structure was formed, which disappears after annealing. As a result of irradiation, a layer of copper oxide CuO formed on the surface of the alloy, which under normal thermal conditions is formed at a temperatures of 400 – 500 °C, and the reflections of the ordered β-phase also disappeared in the near-surface layer. The elemental composition of the alloy changed in depth from the irradiated metal surface. Phases with a low degree of long-range order and an increased content of palladium were formed. The presence of these phases is due mainly to the selective oxidation of copper.
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Nardella, Maria I., Antonio Rosato, Benny D. Belviso, Rocco Caliandro, Giovanni Natile und Fabio Arnesano. „Oxidation of Human Copper Chaperone Atox1 and Disulfide Bond Cleavage by Cisplatin and Glutathione“. International Journal of Molecular Sciences 20, Nr. 18 (06.09.2019): 4390. http://dx.doi.org/10.3390/ijms20184390.
Annotation:
Cancer cells cope with high oxidative stress levels, characterized by a shift toward the oxidized form (GSSG) of glutathione (GSH) in the redox couple GSSG/2GSH. Under these conditions, the cytosolic copper chaperone Atox1, which delivers Cu(I) to the secretory pathway, gets oxidized, i.e., a disulfide bond is formed between the cysteine residues of the Cu(I)-binding CxxC motif. Switching to the covalently-linked form, sulfur atoms are not able to bind the Cu(I) ion and Atox1 cannot play an antioxidant role. Atox1 has also been implicated in the resistance to platinum chemotherapy. In the presence of excess GSH, the anticancer drug cisplatin binds to Cu(I)-Atox1 but not to the reduced apoprotein. With the aim to investigate the interaction of cisplatin with the disulfide form of the protein, we performed a structural characterization in solution and in the solid state of oxidized human Atox1 and explored its ability to bind cisplatin under conditions mimicking an oxidizing environment. Cisplatin targets a methionine residue of oxidized Atox1; however, in the presence of GSH as reducing agent, the drug binds irreversibly to the protein with ammine ligands trans to Cys12 and Cys15. The results are discussed with reference to the available literature data and a mechanism is proposed connecting platinum drug processing to redox and copper homeostasis.