Small Copper Research Articles

Freeform 3D deposition of small diameter copper tubes using a powder-binder feedstock

AbstractCopper is an interesting material for many applications including thermal management devices, which make often use of copper piping. This study proposes a method for the freeform deposition of a copper-binder feedstock, extruded through an additive manufacturing machine. Several tubes have been printed using a special nozzle and varying process parameters. The dimensional results of the deposited specimens at the green state and the physical properties of the tubes after debinding and sintering have been measured. The results demonstrate that piping in serpentine layout can be deposited by extrusion and sintered, even with sharp bends without significant ovalization of the cross-section.

An Electrically Small Patch Antenna Sensor for Salt Concentration Measurement of NaCl Solution.

In this paper, a complementary split-ring resonator (CSRR)-based patch antenna is proposed as a microwave sensor to measure the salt concentration of NaCl solution. The microwave sensor consists of an RF-4 substrate, where a small copper disc is attached on the top as the radiator, a larger copper disc integrated with two CSRRs is attached on the bottom side as the finite ground plane, and a coaxial feeding port is introduced at the ground plane center. During salt concentration sensing, only the top disc is immersed into NaCl solution. The results indicate that the proposed microwave sensor can measure salt concentrations ranging from 5‱ to 35‱ with a maximum sensitivity of 0.367 (kHz/(mg/L)). The proposed microwave sensor is low-cost, low-profile, electrically small, lightweight, and easy to fabricate, and it also can be applied to other solutions' concentration sensing.

Bis(amino acidato)copper(II) compounds in blood plasma: a review of computed structural properties and amino acid affinities for Cu2+ informing further pharmacological research.

Neutral bis(amino acidato)copper(II) [Cu(aa)2] coordination compounds are the physiological species of copper(II) amino acid compounds in blood plasma taking the form of bis(l-histidinato)copper(II) and mixed ternary copper(II)-l-histidine complexes, preferably with l-glutamine, l-threonine, l-asparagine, and l-cysteine. These amino acids have three functional groups that can bind metal ions: the common α-amino and carboxylate groups and a side-chain polar group. In Cu(aa)2, two coordinating groups per amino acid bind to copper(II) in-plane, while the third group can bind apically, which yields many possibilities for axial and planar bonds, that is, for bidentate and tridentate binding. So far, the experimental studies of physiological Cu(aa)2 compounds in solutions have not specified their complete geometries. This paper provides a brief review of my group's research on structural properties of physiological Cu(aa)2 calculated using the density functional theory (DFT) to locate low-energy conformers that can coexist in aqueous solutions. These DFT investigations have revealed high conformational flexibility of ternary Cu(aa)2 compounds for tridentate or bidentate chelation, which may explain copper(II) exchange reactions in the plasma and inform the development of small multifunctional copper(II)-binding drugs with several possible copper(II)-binding groups. Furthermore, our prediction of metal ion affinities for Cu2+ binding with amino-acid ligands in low-energy conformers with different coordination modes of five physiological Cu(aa)2 in aqueous solution supports the findings of their abundance in human plasma obtained with chemical speciation modelling.

Investigating small sized metal blockage effects at 60 and 100 GHz using measurements and modeling approaches

Millimeter wave (mmWave) technologies at 60 GHz and 100 GHz bands are currently gaining significant attention for its potential to meet the demanding needs of next-generation networks. These include ultra-high data rate, ultra-low latency, high spectral efficiency, and high end-to-end reliability. However, mmWave signals’ blockage remains a critical issue that affects the reliability of mmWave at 60 GHz and at 100 GHz bands due to the significant attenuations induced by the blockers (BLs). Not only blockers that have the size of a human body or even larger can affect the signal, but also smaller objects with much narrower dimensions, as narrow as 4 cm, can severely affect the signal strength and introduce an attenuation that reaches up to 12 dB at 100 GHz. In this paper we have conducted new measurements and presented results for three small copper sheets at each frequency band, aiming to investigate the blockage effect of small-sized metal objects on signal strength at these two frequency bands. Also, we have examined the performance of the knife-edge diffraction (KED) blockage model of the third-generation partnership project (3GPP) standards body and its evolved version named the mmMAGIC blockage model in such scenarios. Furthermore, we investigated the applicability of the two blockage models in capturing the attenuation characteristics of other materials-such as wood and glass. Experimental results supported by numerical models have shown that the induced peak attenuations are 5(12) dB, 10(23) dB, 23(23) dB for 4 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 4 cm, 8 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 8 cm, 16 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 16 cm copper blockers, respectively, at 60(100) GHz mmWave bands. Also, we have shown that both the 3GPP and mmMAGIC simulation models fail to accurately capture the attenuation characteristics of materials other than copper. The findings of this work highlight the importance of considering the dimensions and types of blockages when deploying reliable mmWave and sub-THz communications.

Pre-hispanic wetland irrigation and metallurgy in the South Andean Altiplano (Intersalar Region, Bolivia, XIVth and XVth century CE)

The high-altitude Andean Altiplano has been subject to abrupt climate changes during the Holocene. The resulting impact on the hydrological cycle has obliged ancient societies to adapt and develop strategies to face droughts and sustain agropastoral activities. Here, we present the results of archaeological prospections together with the biogeochemical characterization of a well-dated core collected at Saitoco wetland in the arid southern Altiplano (Intersalar Region, Bolivia). Archaeological survey allowed the mapping of a network of channels collecting water from the surrounding mountains to the wetland, and the presence of small copper mines and metallurgical installations. Traces and major element concentrations and accumulation rates, together with elemental and isotopic characterization of organic matter (OM) (i.e., Corg and δ13Corg) in the wetland core have been used to document the evolution of the landscape in relation to climatic and anthropogenic pressure. While OM, bromine (Br), selenium (Se) and mercury (Hg) data were used to assess the variability of precipitations during the Late Holocene (4.2 ka BP to the present), local and regional mining activities have been reconstructed through the variations of lead (Pb), copper (Cu), and antimony (Sb). Our results show an abrupt change in OM composition during the 14th and 15th century CE, characterized by an abrupt shift in δ13Corg synchronous with a rise in Br, Se and Hg, testifying for the waterlogging of the wetland during a known arid period in the region. This change is attributed to anthropogenic transformation of the landscape through the irrigation of the wetland by channeling streams from the surrounding mountains. At the same time, a mining pollution signal was recorded supporting local Cu mining and metallurgy. The mining signal then reached its maximum values during the Inca and Colonial periods, which matches with reported enhanced mining activities in the region. From the colonial era onward, the wetland progressively dried up, likely resulting from the abandonment of the site. Through the combination of a biogeochemical record and archaeological prospections, this study provides evidences that societies of the arid Intersalar region have transformed their landscape and developed wetland irrigation and mining during the arid 14th and 15th century CE Period.

INTERACTION OF COPPER CLUSTERS WITH DIOXIDINE

DFT-modelling with B3LYP5 parametrization was performed for small copper clusters (Cu2, Cu3, Cu13) and their complexes with antibacterial drug dioxidine (2,3-bis-(hydroxymethyl)quinoxaline 1,4-di-N-oxide, Dx). The tendencies of changing of geometry con gurations and interaction energies depending on metal cluster size are identi ed. Dissociation energy increases with the cluster size. The dissociation energy of the most stable “Cu3-Dx” complex is 55.1 kcal/mol. Metal atoms form coordination bonds with either one or two oxygen atoms of in all complexes.

Conductivity and Chemiresistive H2S Gas Sensitivity of Graphene (75 wt%)/ Cu (25 wt%) Composite Thin Film

This paper studies the conductivity and chemiresistive H2S gas sensitivity of graphene (75wt%)-Cu(25wt%) composite thin film, using self-made chamber and common laboratory apparatus. The method adopted involves mixture of 2 drops of ethanol with the synthesized composite and prepared on a glass substrate by tape casting method. Two small copper metal sheets were used as electrodes for clipping of crocodile which were also connected to digital meter for resistance readings and its changes. The X-ray Diffraction (XRD) shows thatannealing temperature reduced the crystallite sizes. The Fourier Transform Infrared Radiation (FTIR) spectra show the functional groups present to be transition metal carbonyls or aromatic combination bands, terminal alkyne (monosubstituted), isothiocyanate and that between 2300 and 2400 cm-1 indicates N=C=S functional group and evidence of CO2 interaction with external surface of the material or intercalating in the interlayer of the host material Also, increase in the conductivity was observed due to decrease in resistivity. The response/sensitivity peak of the sensor to hydrogen sulfide was seen to rise proportionally as temperature rose with percentage 3.97% for as grown, annealed at 200°C is at 12.98% while the annealed at 400°C is at 27.34%.

Optimization of machine learning algorithms for remote alteration mapping

World-class large to sub-economic small porphyry copper deposits (PCDs) are primarily found in the Kerman Cenozoic Magmatic Arc (KCMA) which is a fascinating area for geological remote sensing investigationsbecause of its well-exposed rocks and roughly vegetated surfaces. Remote hydrothermal alteration mapping is a critical component of mineral exploration and resource assessment, vital for identifying PCDs. This study explored the application of ML techniques, such as quadratic discriminant analysis (QDA), cosine K-nearest neighbor (CKNN), and bagging decision tree (BDT), in remote hydrothermal alteration mapping. Moreover, the study highlights the transformative impact of optimization methods such as grid search (GS), random search (RS), Bayesian optimization (BO), and principal component analysis (PCA) methods in fine-tuning these algorithms to achieve superior results. These algorithms were found accurate and helpful in identifying PCD-related argillic, phyllic, propylitic, and iron oxide/hydroxide alteration-type zones based on field observations, petrographic studies, and XRD analysis. This research revealed evidence for widespread phyllic and silicic alteration zones, as well as confined argillic and iron oxide/hydroxide zones surrounded by wider regions of propylitic alteration. As the field of ML continues to advance, the future holds promise for even more refined and innovative approaches to hydrothermal alteration mapping. This study underscores the pivotal role that optimized ML algorithms play in revolutionizing mineral exploration practices and paving the way for a more sustainable and responsible resource assessment industry.

Small Copper Nanoclusters Synthesized through Solid-State Reduction inside a Ring-Shaped Polyoxometalate Nanoreactor.

Cu nanoclusters exhibit distinctive physicochemical properties and hold significant potential for multifaceted applications. Although Cu nanoclusters are synthesized by reacting Cu ions and reducing agents by covering their surfaces using organic protecting ligands or supporting them inside porous materials, the synthesis of surface-exposed Cu nanoclusters with a controlled number of Cu atoms remains challenging. This study presents a solid-state reduction method for the synthesis of Cu nanoclusters employing a ring-shaped polyoxometalate (POM) as a structurally defined and rigid molecular nanoreactor. Through the reduction of Cu2+ incorporated within the cavity of a ring-shaped POM using H2 at 140 °C, spectroscopic studies and single-crystal X-ray diffraction analysis revealed the formation of surface-exposed Cu nanoclusters with a defined number of Cu atoms within the cavities of POMs. Furthermore, the Cu nanoclusters underwent a reversible redox transformation within the cavity upon alternating the gas atmosphere (i.e., H2 or O2). These Cu nanoclusters produced active hydrogen species that can efficiently hydrogenate various functional groups such as alkenes, alkynes, carbonyls, and nitro groups using H2 as a reductant. We expect that this synthesis approach will facilitate the development of a wide variety of metal nanoclusters with high reactivity and unexplored properties.

Structural and Tribological Analysis of Brake Disc–Pad Pair Material for Cars

The study of the tribological behavior of the braking system in auto vehicles requires knowing the characteristics of the material in contact and, in the work process, the friction pair brake disc pads. Material structural analysis is necessary because the wear process depends both on the friction-pair chemical composition (brake disc pads) and on the work process parameters (pressing force, rotational speed, traffic conditions, etc.). The material of the brake discs is generally the same, gray cast iron, and the brake pads can be semimetallic (particles of steel, copper, brass, and graphite, all united with a special resin), organic materials (particles of rubber, glass, and Kevlar, all joined with the help of a resin), composite materials that contain different constituents, and ceramic materials (rarely have small copper particles). Therefore, the purpose of this paper is to analyze the crystalline structure, tribological behavior (at friction and wear), and the mechanical properties of the materials of the brake disc–pad friction pair specific to the field through study and analysis.

Joint stochastic optimisation of stope layout, production scheduling and access network

The three main optimisation components of sublevel stoping methods are stope layout, production schedule (or stope sequencing) and access networks. The joint optimisation of these components could further add value to an underground mining project. This potential has not been considered in the literature due to computational difficulties, and the problem was solved sequentially. This paper proposes a new joint optimisation model to integrate these components. In addition, the proposed optimisation model incorporates stochastic simulations to capture uncertainty and variability associated with the grades of the related mineral deposits mined. The optimisation model is based on a two-stage stochastic integer programming (SIP) formulation that maximises the project's net present value (NPV) and minimises the planned dilution. Applying the proposed method at a small copper deposit shows that the SIP outperforms the results obtained from mixed integer programming. For a seven-year mine life, the SIP model generated ∼20% more NPV, demonstrating the importance of developing a joint optimisation formulation and accounting for grade uncertainty and variability.

The Influence of Glass Fiber and Copper Wire z-Binder on the Mechanical Properties of 3D Woven Polymeric Composites

AbstractThree-dimensional composites (3D) have potential applications in various fields due to their enhanced properties compared to conventional two-dimensional composites (2D). This study investigates the effect of different volumes of z-binder made from copper wire and E-glass fiber on the mechanical properties of 3D woven polymeric composites. The tensile, flexural, and fracture toughness behavior of four types of 3D orthogonal woven composites were studied in addition to a comparative 2D composite. The creation of the 3D orthogonal single-ply fabrics involved weaving z-binders using two different copper wire diameters, single fiber bundles, and double fiber bundles, each combined with four layers of woven E-glass fiber. The consolidation process for both 2D fabric and single-fabric 3D woven composites was executed using the hand lay-up technique. The results showed that most 3D woven composites outperformed 2D composites in terms of fracture toughness (stress intensity factor KIC and energy release rate GIC) and flexural strain. However, a decrease in flexural strength and tensile properties was observed for all 3D composites. The specimen with a small copper diameter had the smallest decrease of 5% in tensile strength. Furthermore, a decrease of 9% and 21% was attained by reinforcing with double and single glass fiber bundle z-binders, respectively, as compared with 2D composites. The highest enhancement of 92.5% in flexural failure strain was attained with double glass fiber bundles of z-binder. The maximum improvement in KIC fracture toughness, reaching 126% and 101.5%, was observed in specimens with a single glass fiber bundle z-binder and those with a large copper wire diameter, respectively.

Lead isotopes of prehistoric copper tools define metallurgical phases in Late Neolithic and Eneolithic Italy.

The diffuse presence of small copper ore deposits in the Alpine area, mostly exploited since Late Medieval times, led most scholars to assume that these deposits may actually be active much earlier and that many of the circulating prehistoric metal objects found in the area were produced with local copper sources. This assumption was recently validated for the Recent Bronze Age through the use of lead isotope tracers, and well supported by the archaeometallurgical evidences found in the South-Eastern Alps. However, the scarcity of available lead isotope data for pre-Bronze Age metals precluded to date the reconstruction of the metal flow through the Late Neolithic and Eneolithic (or Copper Age). Based on 49 new analyses of important archaeological objects from the Alpine region, the Po River Valley and Central Italy, mostly axes dated from the Late Neolithic to the Late Eneolithic, here we show that the diffusion of copper in Northern Italy (approximately 4500-2200 BC) includes three major periods of metal use and/or production, each related to specific ore sources. The South Alpine copper was massively used only starting from the middle of the 3rd millennium BC, in connection or slightly earlier than the Beaker event.

Sub-picosecond photodynamics of small neutral copper oxide clusters.

The ultrafast dynamics of neutral copper oxide clusters (CunOx, n < 5) are reported using femtosecond pump probe spectroscopy in the gas phase. The transient spectra recorded for each cluster demonstrate they relax on a 100s of fs timescale followed by a long-lived (>50 ps) response. Density functional theory calculations are performed to determine the lowest energy structures and spin states. Topological descripters for the excited states are calculated (time-dependent density functional theory) to relate the measured excited state dynamics to changes in the cluster's electronic structure with increasing oxidation. Strong field ionization is demonstrated here to be a soft form of ionization and able to record transient signals for clusters previously determined to be unstable to nanosecond multiphoton ionization. The relative cluster stability is further demonstrated by signal enhancement/depreciation that is recorded through the synergy from the two laser pulses. Once the oxygen atoms exceed the number of copper atoms, a weakly bound superoxide O2 unit forms, exhibiting a higher spin state. All clusters that are not in the lowest spin configuration demonstrate fragmentation.

A Novel Procedure for Friction Stir Welding Aluminium to Copper by Using an Aluminium Run-On Plate

Conventional friction stir welding of aluminium to copper often results in the formation of deleterious intermetallic compounds. In order to overcome this concern, an innovative procedure consisting of using an aluminium run-on plate is presented. Long continuous aluminium-copper welds, without any defect, were obtained by this procedure. The run-on plate inhibits the formation of intermetallic compounds around the pin by allowing the use of high tool offset, without the formation of discontinuities at the interface. The generation of an aluminium volume around the tool, which detaches very small copper particles from the copper plate, gives rise to stir zones composed of a uniform distribution of copper particles in an aluminium matrix and with a minimal formation of intermetallic compounds. Comparing to the conventional welds, a significant improvement in the mechanical strength was achieved by welding with this non-conventional procedure.

Novel dynamic method based on CV-SECM and SWV-SECM for the in situ chemical imaging of reactive metal surfaces undergoing corrosion and corrosion inhibition illustrated with the case of copper corrosion inhibition by benzotriazole

A novel dynamic method for the chemical imaging of actively corroding metal surfaces using scanning electrochemical microscopy (SECM) is proposed by using CV-SECM and SWV-SECM. This consists of an adequate coupling of a repetitive voltammetric operation at the SECM tip while conducting the rastering routine for scanning a reactive copper surface, as well as its inhibition by benzotriazole. In this method, gold microelectrodes are employed as SECM tips, and therefore their electrochemical behaviour towards collection and redissolution of Cu2+ ions from synthetic solutions containing Cu2+ ions. Next, the dynamic application of voltammetric methods for the collection and stripping of copper on the Au probes while mapping copper surfaces was investigated. The proof of concept first involved continuous cyclic voltammetry (CV-SECM) in an acidified NaCl solution, in terms of Cu2+ dissolution and surface redox activity (with SECM in the feedback mode). Then, square wave voltammetry (SWV-SECM) was used to detect small copper dissolution from corroding and inhibitor-protected metal surfaces. The results are consistent with a heterogeneous nature of copper degradation and the development of protective films and passive layers.

Probing the Bioinorganic Chemistry of Cu(I) with 111Ag Perturbed Angular Correlation (PAC) Spectroscopy

The two most common oxidation states of copper in biochemistry are Cu(II) and Cu(I), and while Cu(II) lends itself to spectroscopic interrogation, Cu(I) is silent in most techniques. Ag(I) and Cu(I) are both closed-shell d10 monovalent ions, and to some extent share ligand and coordination geometry preferences. Therefore, Ag(I) may be applied to explore Cu(I) binding sites in biomolecules. Here, we review applications of 111Ag perturbed angular correlation (PAC) of γ-ray spectroscopy aimed to elucidate the chemistry of Cu(I) in biological systems. Examples span from small blue copper proteins such as plastocyanin and azurin (electron transport) over hemocyanin (oxygen transport) to CueR and BxmR (metal-ion-sensing proteins). Finally, possible future applications are discussed. 111Ag is a radionuclide which undergoes β-decay to 111Cd, and it is a γ-γ cascade of the 111Cd daughter nucleus, which is used in PAC measurements. 111Ag PAC spectroscopy may provide information on the coordination environment of Ag(I) and on the structural relaxation occurring upon the essentially instantaneous change from Ag(I) to Cd(II).

Investigation of the Structural and Mechanical Properties of ((82-X) Sn –XCu -18 In) % Alloy with X= 1,2,3,4and 5

Materials Science is concerned with the development or synthesis of new materials . For this reason our interest is focused on the fabrication of new materials , such as lead free solder alloys . Sn-In alloys offer very low melting points and bond well with copper .This study aims to investigate The Structural and mechanical properties of (82-x)Sn -18In alloys with added copper .The Samples were prepared by melting technology From high purity (99 %) elements tin ,indium and copper .XRD showed the formation of a single phase hexagonal structure with a small copper plane, and the addition of copper decreased the particle size of the (82-x)Sn -18 In. The creep test results showed that Cu-containing solder alloys exhibited significant improvements in creep resistance. However, the average activation energy decreases with copper addition from 0.322 to 0.247 eV.

Comparative DFT Study of Small Anionic Silver and Copper Clusters: Evolution of Structure and Physicochemical Properties

Comparative DFT Study of Small Anionic Silver and Copper Clusters: Evolution of Structure and Physicochemical Properties

A DFT + U Study on the Stability of Small CuN Clusters (N = 3–6 Atoms): Calculation of Phonon Frequencies

Despite the interest in copper clusters, a consensus on their atomic structure is still lacking. The experimental observation of isolated clusters is difficult, and theoretical predictions vary widely. The latter is because one must adequately describe the closed shell of d electrons both in its short- and long-range effects. Herein, we investigate the stability of small copper clusters (CuN, N = 3–6 atoms) using spin-polarized DFT calculations under the GGA approximation, the Hubbard U correction, and the van der Waals forces. We found that the spin-polarized and vdW contributions have little effect on the binding energies of the isomers. The inclusion of U represents the most relevant contribution to the ordering of the CuN isomers, and our calculated binding energies for the clusters agreed with the experimental values. We also found that atomic relaxations alone are not enough to determine the stability of small copper clusters. It is also necessary to build the energy landscape or calculate the vibrational frequencies of the isomers. We found that the vibrational frequencies of the isomers were in the THz range and the normal modes of vibration were discrete. This approach is relevant to future studies involving isolated or supported copper clusters.