Single Copper Research Articles

Bronze production in the Ancient Chengdu Plains: A diachronic metallurgical perspective on a separate cultural region

• Novel, diachronic research on bronze production in the Chengdu Plains. • Different lead sources and possibly a single copper source used for 600 years. • New evidence on the origins of Sanxingdui bronze. As one of the most important separate cultural regions in ancient China, the Chengdu Plains provide a unique example to explore the development of bronze production. We analysed 37 bronze objects from the Western Zhou period to the Tang Dynasty in the Chengdu Plains for elemental compositions, microstructure, and lead isotope ratios. We referred to bronze data from the Sanxingdui sacrificial pits to compare results that demonstrated that most samples from the Chengdu Plains were Cu-Pb-Sn alloys with variable tin and lead content. The alloy technique used in the Warring States period bronzes, which were uncovered in the Baishoulu cemetery, differed from the techniques used in other samples. Casting is the major technique used for all types of objects in different periods. The only cold-worked and annealed sample found so far was a Chu-style vessel. Different lead sources and a possible single copper source were constantly used in local bronze production from the Western Zhou Dynasty to the Warring States period (more than 600 years). Some coins in Han and Tang Dynasty potentially also used these same lead sources. Comparison with Sanxingdui bronze suggests that both lead and copper sources of Sanxingdui bronzes are different from the later metal sources. We therefore propose that the Sanxingdui bronze might not have been locally made or was made with outside materials. Our study suggests that diachronic study on bronze production could provide clues to solve more archaeological questions other than the development of bronze production.

Microstructural investigations on bonding mechanisms of cold-sprayed copper with SS316L steel

ABSTRACT The purpose of the study was to understand the adhesion mechanism between cold-sprayed copper and SS316L steel substrate. Coatings of 3-mm thickness were deposited by cold-spraying on steel substrates prepared with different roughness values. To understand the bonding mechanism of the coating with substrates, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analyses were done on interfacial surfaces; exposed after the adhesion testing. Additionally, cross-sectional as-well-as top surface deformation behaviour of single copper particles deposited on steel substrates was investigated by using SEM/EDS, to elucidate the mechanism behind bonding. The results of the study validated that the adhesion is governed by both metallurgical bonding, as-well-as, mechanical interlocking, owing to the jetting formation. The mirror-polished surface resulted in a better adhesion strength as compared to the as-received and semi-polished surfaces, which was further validated by ultrasonic testing. Also, smaller-sized particles were found to be favourable for good adhesion strength.

Synergistic Copper-Catalyzed Reductive Aminocarbonylation of Alkyl Iodides with Nitroarenes.

We have developed a Cu-catalyzed reductive aminocarbonylation of alkyl iodides using nitroarenes as the nitrogen source. The reaction proceeds with a single copper catalyst playing dual roles of synergistically mediating both carbonylation of alkyl iodides and reduction of nitroarenes, providing acyl iodides and anilines as possible reactive intermediates that then do amide coupling spontaneously. A diverse range of secondary N-aryl alkylamides are accessible from a variety of primary, secondary, and tertiary alkyl iodides using this method.

Predicting the flow stress and dominant yielding mechanisms: analytical models based on discrete dislocation plasticity

Dislocations are the carriers of plasticity in crystalline materials. Their collective interaction behavior is dependent on the strain rate and sample size. In small specimens, details of the nucleation process are of particular importance. In the present work, discrete dislocation dynamics (DDD) simulations are performed to investigate the dominant yielding mechanisms in single crystalline copper pillars with diameters ranging from 100 to 800 nm. Based on our simulations with different strain rates and sample size, we observe a transition of the relevant nucleation mechanism from “dislocation multiplication” to “surface nucleation”. Two physics-based analytical models are established to quantitatively predict this transition, showing a good agreement for different strain rates with our DDD simulation data and with available experimental data. Therefore, the proposed analytical models help to understand the interplay between different physical parameters and nucleation mechanisms and are well suitable to estimate the material strength for different material properties and under given loading conditions.

Nano-patterned honeycomb structure of monolayer copper selenide on Cu(111)

Transition metal dichalcogenides generally have three atomic layers forming a buckled honeycomb structure as a covalent sheet. The van der Waals force is the key interaction between these sheets. In our work, we have fabricated a single layered copper selenide structure by employing molecular beam epitaxy method. The selenium and copper atoms form a Moiré pattern with respect to the substrate Cu(111). Combined with density functional theory calculation, the narrow band gap of these structures is investigated in detail.

Molecular tuning of CO2-to-ethylene conversion.

The electrocatalytic reduction of carbon dioxide, powered by renewable electricity, to produce valuable fuels and feedstocks provides a sustainable and carbon-neutral approach to the storage of energy produced by intermittent renewable sources1. However, the highly selective generation of economically desirable products such as ethylene from the carbon dioxide reduction reaction (CO2RR) remains a challenge2. Tuning the stabilities of intermediates to favour a desired reaction pathway can improve selectivity3-5, and this has recently been explored for the reaction on copper by controlling morphology6, grain boundaries7, facets8, oxidation state9 and dopants10. Unfortunately, the Faradaic efficiency for ethylene is still low in neutral media (60 per cent at a partial current density of 7 milliamperes per square centimetre in the best catalyst reported so far9), resulting in a low energy efficiency. Here we present a molecular tuning strategy-the functionalization of the surface of electrocatalysts with organic molecules-that stabilizes intermediates for more selective CO2RR to ethylene. Using electrochemical, operando/in situ spectroscopic and computational studies, we investigate the influence of a library of molecules, derived by electro-dimerization of arylpyridiniums11, adsorbed on copper. We find that the adhered molecules improve the stabilization of an 'atop-bound' CO intermediate (that is, an intermediate bound to a single copper atom), thereby favouring further reduction to ethylene. As a result of this strategy, we report the CO2RR to ethylene with a Faradaic efficiency of 72 per cent at a partial current density of 230milliamperes per square centimetre in a liquid-electrolyte flow cell in a neutral medium. We report stable ethylene electrosynthesis for 190hours in a system based on a membrane-electrode assembly that provides a full-cell energy efficiency of 20 per cent. We anticipate that this may be generalized to enable molecular strategies to complement heterogeneous catalysts by stabilizing intermediates through local molecular tuning.

Hollow waveguide integrated laser spectrometer for 13CO2/12CO2 analysis.

Using hollow waveguide hybrid optical integration, a miniaturized mid-infrared laser absorption spectrometer for 13CO2/12CO2 isotopologue ratio analysis is presented. The laser analyzer described focuses on applications where samples contain a few percent of CO2, such as breath analysis and characterization of geo-carbon fluxes, where miniaturization facilitates deployment. As part of the spectrometer design, hollow waveguide mode coupling and propagation is analyzed to inform the arrangement of the integrated optical system. The encapsulated optical system of the spectrometer occupies a volume of 158 × 60 × 30 mm3 and requires a low sample volume (56 µL) for analysis, while integrating a quantum cascade laser, coupling lens, hollow waveguide cell and optical detector into a single copper alloy substrate. The isotopic analyzer performance is characterized through robust error propagation analysis, from spectral inversion to calibration errors. The analyzer achieves a precision of 0.2‰ in 500 s integration. A stability time greater than 500 s was established to allow two-point calibration. The accuracy achieved is 1.5‰, including a contribution of 0.7‰ from calibrant gases that can be addressed with improved calibration mixtures.

Direct Conversion of Biomass into Compact Air Electrode with Atomically Dispersed Oxygen and Nitrogen Coordinated Copper Species for Flexible Zinc–Air Batteries

Developing low-cost flexible air electrodes with bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities is the key to the performance of flexible rechargeable metal–air batteries. Herein oxygen and nitrogen coordinated single copper atom active sites anchored within porous carbon electrode (sCu-ONPC) are synthesized by direct pyrolysis of adsorption of Cu2+-saturated well-cutting biomass brinjaul. This as-synthesized sCu-ONPC electrode exhibits outstanding electrocatalytic performances toward ORR with a half-wave potential value (0.79 V vs RHE) and an onset potential (0.95 V vs RHE), and OER with an overpotential of 275 mV when the current density reaches 10 mA cm–2, thus delivering a high power density of 88.5 mW cm–3 at 140 mA cm–2 and excellent cycling stability when directly assembling as a Zn–air battery. Significantly, density functional theory calculation reveals that the simultaneous O and N coordinated Cu atom, especially the Cu–N3O species, possess excellent ...

Structural analysis and role of cation distribution on the magnetic properties of single phase Ni-doped copper chromium ferrite

A series of single-phase spinel structure was prepared by the standard ceramic technique in order to study the effect of cation doping on the microstructure and magnetic properties of spinel ferrite. We have used six Ni concentrations in the doping process of mixed spinel (Mg, Cu, Cr ferrite). Single-phase formation for all the prepared samples was confirmed using X-ray diffraction. Rietveled refinement was applied to study the structural characteristics and the cation distribution of the compounds. The refined data showed that the Mg cations have tetrahedral site preference, while Ni and Cr cations prefer the octahedral site. Hence replacing Ni cation by Mg cation forces the structure to be normal spinel. With increasing Ni content the unit cell dimension decreases and the degree of inversion increases. Accordingly the microstrain decreases, while the crystallite size tend to increase as Ni content increases. From the magnetic measurements it was found that, the magnetic susceptibility decreases with increasing temperature which revealed the normal behaviour of the spinel ferrite. The Curie temperature was found to increase with increasing the Ni content. The impressive results obtained were the decrease of the effective magnetic moment and the exchange interaction constant JBA with increasing Ni content. The results show that the magnetic nature of the doping element does not play a major role in determining the final magnetic properties of the compound. Instead, the cation distribution is the significant parameter.

Growth and physiological effects of single and combined Cu, NaCl, and water stresses on Atriplex atacamensis and A. halimus

Halophyte species have been proposed as suitable candidates for the phytostabilization of metal enriched sites in arid and semiarid ecosystems, but co-occurring conditions, such as salinity and water stress, can affect plant growth and colonization. In this work, we determined the effect of single and combined copper (Cu), salt (NaCl), and water stress on growth and tolerance strategies used by two xerohalophyte species of the genus Atriplex: Chilean A. atacamensis and European A. halimus. Seedlings of both species were subjected to 5 and 10 u M Cu, 0.5% NaCl, and 7.85 mM polyethylene glycol 6000 (PEG) in hydroponic cultures to create single and combined stress treatments. A single Cu stressor decreased growth parameters of both species, with a higher effect on A. atacamensis. Copper accumulation was higher in roots, which can be related to an increase of root non-protein thiols (NPT). Single NaCl had no negative effects on growth but increased leaf sodium (Na). Single PEG decreased shoot growth, especially in A. halimus, but had no effect on GSH expression. A combination of Cu, NaCl, and PEG further decreased growth parameters, but did not decrease glutathione, proline, or non-protein thiol expression. Atriplex atacamensis and A. halimus are affected differently by combined stresses, but both species show an active tolerance response to the presented conditions.

Cupric and Chloride Ions: Leaching of Chalcopyrite Concentrate with Low Chloride Concentration Media

In this paper, the effect of the cupric and chloride ions concentrations on copper dissolution from chalcopyrite concentrate was studied in acidified media. Variables included three different concentrations of Cu2+ (0.5, 1.5, and 2.5 g L−1), four different concentrations of Cl− (0, 5, 7, and 10 g L−1), two different pH values of 1 and 2, and a constant temperature of 60 °C. Results indicated that addition of Cl− to the system improves copper extractions, especially at higher concentrations of Cu2+. Initial copper concentrations in the leaching solution did not significantly affect the copper extraction when Cl− was not present. Better copper extractions were obtained at pH 1 as compared with pH 2. As the Cu2+ and Cl− concentrations were increased, higher values of redox potential were obtained. According to the formation constants of the chloro-complexes, the predominant species in the Cu2+/Cl− system in the studied interval were CuCl+ and Cu2+. Using a model of copper speciation in the experimental range predicted for a single copper concentration with increasing Cl− concentration, the Cu2+ concentration decreased significantly while the concentration of the chloro-complex species CuCl+ increased. In the leached residue, evidence of sulfur formation was found using SEM and corroborated by XRD analysis. When chloride is present in the medium, the amounts of copper and iron in the residue decrease, confirming a positive effect of chloride on the extraction of copper from concentrate for the studied conditions.

A Crystal Plasticity Model with Irradiation Effect for the Mechanical Behavior of FCC Metals

In this paper, a crystal plasticity model considering the irradiation effect based on the thermal activation theory is established. The evolutions of screw dislocations, edge dislocations, and stacking fault tetrahedrals (SFTs) (induced by irradiation) are included into the model. The interactions between dislocations and irradiation-induced SFTs are also considered. The constitutive model is numerically implemented on the ABAQUS platform through UMAT subroutine and applied to study the irradiation effect on the mechanical behavior of pure copper. The mechanical properties of single and polycrystalline copper are studied, and the simulation results show that the constitutive model can properly predict the mechanical behavior of irradiated pure copper. Especially for polycrystalline copper, the simulation results are in good agreement with the experimental data.

Train of Single Molecule-Gears.

Two molecule-gears, 1.2 nm in diameter with six teeth, are mounted each on a single copper adatom separated exactly by 1.9 nm on a lead surface using a low-temperature scanning tunneling microscope (LT-STM). A functioning train of two molecule-gears is constructed complete with a molecule-handle. Not mounted on a Cu adatom axle, this ancillary molecule-gear is mechanically engaged with the first molecule-gear of the train to stabilize its step-by-step rotation. Centered on its Cu adatom axle, the rotation of the first gear of the train step by step rotates the second similar to a train of macroscopic gears. From the handle to the first and to this second molecule-gear, the exact positioning of the two Cu adatom axles on the lead surface ensures that the molecular teeth-to-teeth mechanics is fully reversible.

Aged microplastics polyvinyl chloride interact with copper and cause oxidative stress towards microalgae Chlorella vulgaris

Microplastics (MPs) could pose potential risks to microalgae, the primary producer of marine ecosystems. Currently, few studies focus on the interaction of aged MPs with other pollutants and their toxic effects to microalgae. Therefore, the present study aimed to investigate i) the aging of microplastics polyvinyl chloride (mPVC) in simulated seawater and the changes in physical and chemical properties; ii) the effects of single mPVC (virgin and aged) and copper on microalgae Chlorella vulgaris; and iii) the interaction of aged mPVC and copper and the oxidative stress towards C. vulgaris. In this study, some wrinkles, rough and fractured surface textures can be observed on the aged mPVC, accompanying with increased hydroxyl groups and aromatic carbon-carbon double bond but decreased carbon hydrogen bond. It was found that single virgin or aged mPVC at low concentration (10 mg/L) had significant inhibition on the growth of C. vulgaris but no inhibition at higher concentration (100, 1,000 mg/L), which can be reasonably explained by the aggregation and precipitation of mPVC at high concentration. The aging of mPVC inhibited the growth of C. vulgaris with the maximum growth inhibition ratio (IR) of 35.26% as compared with that of virgin mPVC (IR = 28.5%). However, the single copper could significantly inhibit the growth of C. vulgaris and the inhibitory effects increased with concentration (0.2, 0.5, 1.0 mg/L). Furthermore, both the single aged mPVC (10 mg/L) and copper (0.5 mg/L) caused serious cell damage, although the concentration of superoxide dismutase (SOD) and the intracellular malonaldehyde (MDA) increased. In contrast to single treatment, the growth of C. vulgaris can be enhanced by the combined group with copper (0.5 mg/L) and aged mPVC (10 mg/L).

Interaction of dislocation with GP zones or θ" phase precipitates in aluminum: Atomistic simulations and dislocation dynamics

We investigate the interaction of edge dislocation in aluminum matrix with GP zones and θ″ phase with molecular dynamics (MD) simulations. All these copper-containing precipitates have a form of single or multilayer parallel copper disks separated by planes of aluminum atoms. The maximal number of copper layers of θ″ phase considered in the present work is equal to six; the diameter of precipitates varies from 3 to 15 nm. It is shown that all types of precipitates are initially overcome by dislocation with formation of the Orowan loop around them. The most fragile precipitate is GP zone of first type with a 3 nm diameter; it is sheared during the first closure of the Orowan loop by magnitude of leading partial dislocation, and obtains an additional displacement of trailing partial after the dislocation detachment. The remaining inclusions, even GP zones of a larger diameter, demonstrate the process of accumulation of surface deformation over time due to the shift of the upper half of the copper atom disks relative to the lower one. The moments of separation of the shifted halves are determined for different types of inclusion. Cutting of the strongest six-layer θ″ phase is not observed during our MD simulations. The evolution of local stress acting on copper atoms is traced over the several interactions required for the complete shearing of obstacle. The maximal local stress reached during deformation of GP of the first type of the smallest size is equal to 1.5 GPa, while the substantial increase in acting local stress is registered for higher number of copper disks. The local stress of 5.7 GPa is observed during the sequential interactions of dislocation with six-layer θ″ phase. The entire MD system demonstrate analogical growth of the average level of acting stress simultaneously with the increase in local stress on inclusion; it varies from about 125 MPa in the case of smallest GP zone to about 670 MPa for the hardest θ″ phase. The MD data is generalized in the form of the model of dislocation dynamics at interaction with precipitate. The model was previously proposed by Krasnikov and Mayer (2019) for the case of θ′ phase in aluminum. In the present work, it is modified by accounting the change in the energy of the dislocation core during contact with different types of inclusions. The energy values are fitted from a comparison of the time dependences of average stress in system with MD data. Variation of the core energy for the dislocation line segments attached to precipitate allows us to take into account specific features of precipitates with different number of layers.

Electroreduction of CO2 on Single‐Site Copper‐Nitrogen‐Doped Carbon Material: Selective Formation of Ethanol and Reversible Restructuration of the Metal Sites

AbstractIt is generally believed that CO2 electroreduction to multi‐carbon products such as ethanol or ethylene may be catalyzed with significant yield only on metallic copper surfaces, implying large ensembles of copper atoms. Here, we report on an inexpensive Cu‐N‐C material prepared via a simple pyrolytic route that exclusively feature single copper atoms with a CuN4 coordination environment, atomically dispersed in a nitrogen‐doped conductive carbon matrix. This material achieves aqueous CO2 electroreduction to ethanol at a Faradaic yield of 55 % under optimized conditions (electrolyte: 0.1 m CsHCO3, potential: −1.2 V vs. RHE and gas‐phase recycling set up), as well as CO electroreduction to C2‐products (ethanol and ethylene) with a Faradaic yield of 80 %. During electrolysis the isolated sites transiently convert into metallic copper nanoparticles, as shown by operando XAS analysis, which are likely to be the catalytically active species. Remarkably, this process is reversible and the initial material is recovered intact after electrolysis.

Electroreduction of CO2 on Single-Site Copper-Nitrogen-Doped Carbon Material: Selective Formation of Ethanol and Reversible Restructuration of the Metal Sites.

It is generally believed that CO2 electroreduction to multi-carbon products such as ethanol or ethylene may be catalyzed with significant yield only on metallic copper surfaces, implying large ensembles of copper atoms. Here, we report on an inexpensive Cu-N-C material prepared via a simple pyrolytic route that exclusively feature single copper atoms with a CuN4 coordination environment, atomically dispersed in a nitrogen-doped conductive carbon matrix. This material achieves aqueous CO2 electroreduction to ethanol at a Faradaic yield of 55 % under optimized conditions (electrolyte: 0.1 m CsHCO3 , potential: -1.2 V vs. RHE and gas-phase recycling set up), as well as CO electroreduction to C2 -products (ethanol and ethylene) with a Faradaic yield of 80 %. During electrolysis the isolated sites transiently convert into metallic copper nanoparticles, as shown by operando XAS analysis, which are likely to be the catalytically active species. Remarkably, this process is reversible and the initial material is recovered intact after electrolysis.

Thermal and hydrodynamic fragmentation of continuous molten copper droplets penetrating into sodium pool

To fully investigate the hydrodynamic and thermal fragmentation mechanism of the molten metallic fuels, the experiments of dropping 20–100 g continuous molten copper droplets into sodium were conducted with high ambient Weber number (477<Wea<566), as the supplement of the previous continuous copper droplets experiments with relatively low Wea (87<Wea<339). It is found that the fragmentation changes sharply under the low thermal and hydrodynamic conditions, and changes slowly under the relatively high thermal and hydrodynamic conditions. For the continuous copper droplets, the effect of mass is negligible on the fragmentation degree. The comparisons show that fragments of continuous droplets tend to have a smaller dimensionless mass median diameter (Dm/D0) value than that of single droplet fragments and have a larger Dm/D0 value than that of copper jet fragments under the similar conditions. The empirical correlations, which take the thermal and hydrodynamic effects into consideration, are proposed to calculate the Dm/D0 values of the continuous copper droplets, single copper droplet and copper jet fragments. These results are helpful for predicting the fragment size and termination in CDAs and promising to the development of the core safety codes and the design of reactor core in SFRs.

A Bivalent Inhibitor of Prostate Specific Membrane Antigen Radiolabeled with Copper‐64 with High Tumor Uptake and Retention

AbstractMolecules containing lysine‐ureido‐glutamate functional groups bind to the active site of prostate specific membrane antigen, which is overexpressed in prostate cancer. To prepare copper radiopharmaceuticals for the diagnosis and therapy of prostate cancer, macrobicyclic sarcophagine ligands tethered to either one or two lysine‐ureido‐glutamate functional groups through an appropriate linker have been prepared. Sarcophagine ligands can be readily radiolabeled with positron‐emitting copper‐64 at room temperature. The bivalent agent, in which two targeting groups are tethered to a single copper complex, dramatically outperforms the monomeric agent with respect to tumor uptake and retention. The high tumor uptake, low background, and prolonged tumor retention, even at 24 hours post injection, suggest the bivalent agent is a promising diagnostic for prostate cancer and could be used for prospective dosimetry for therapy with a copper‐67 variant.

A Bivalent Inhibitor of Prostate Specific Membrane Antigen Radiolabeled with Copper-64 with High Tumor Uptake and Retention.

Molecules containing lysine-ureido-glutamate functional groups bind to the active site of prostate specific membrane antigen, which is overexpressed in prostate cancer. To prepare copper radiopharmaceuticals for the diagnosis and therapy of prostate cancer, macrobicyclic sarcophagine ligands tethered to either one or two lysine-ureido-glutamate functional groups through an appropriate linker have been prepared. Sarcophagine ligands can be readily radiolabeled with positron-emitting copper-64 at room temperature. The bivalent agent, in which two targeting groups are tethered to a single copper complex, dramatically outperforms the monomeric agent with respect to tumor uptake and retention. The high tumor uptake, low background, and prolonged tumor retention, even at 24 hours post injection, suggest the bivalent agent is a promising diagnostic for prostate cancer and could be used for prospective dosimetry for therapy with a copper-67 variant.