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Creatinine is one of the most important biomarkers to detect renal failures. The electrochemical detection of creatinine has been performed using complex enzymatic and non-enzymatic electrode arrays hindering their commercialization. In this work, a new and practical non-enzymatic electrochemical sensor was fabricated depositing copper on carbon paper electrodes by physical vapor deposition (namely Cu/CP). Surface and cross-sectional SEM images demonstrated the deposition of copper over the 3D structure of carbon paper. A thin film was found on the surface, while Cu nanowires with diameters of 180 ± 30 nm were found inside the 3D structure of CP. The thickness of the Cu film on the tubular structures of CP was of 390 ± 40 nm. High-resolution TEM images indicated that the Cu film was integrated by hierarchical structures containing terminal Cu hemispheres of 17.6 ± 2.2 nm. Additionally, interplanar distances from the selected-area electron diffraction pattern demonstrated the presence of Cu0, while Cu2O was also found. Creatinine concentrations in saliva between 16 and 400 µM indicate kidney failure. The Cu/CP electrochemical sensor detected creatinine with linear concentration ranges from 0 to 1000 µM with a r2 = 0.9936. Outstandingly, this sensor presented good reproducibility (RSD = 7.3%), and selectivity to detect creatinine in artificial saliva using interferents like urea, glucose, glycine, ascorbic and uric acids. [ABSTRACT FROM AUTHOR]

Since it is difficult to obtain 3D micro-electrodes, simple micro-electrodes with round or rectangular cross-sections are used when performing layer-by-layer scanning EDM to machine 3D micro-structures. This process can process 3D micro-structure, which has deficiencies of complicated technical process and low processing efficiency. In the study, copper was used to fabricate 3D micro-electrodes by micro-milling. Using a reciprocating processing method, micro-EDM was conducted with the 3D micro-electrodes to obtain 3D micro-structures. This method had the advantages of high processing efficiency and a simple technical process. The above work is the main content and novelty of this paper. The paper detailedly studied the effects of the stand-off distance and flushing quantity of dielectric fluid on the machining quality of 3D micro-structure. Furthermore, the effects of rough machining and finish machining on the machined surface were also analyzed. Finally, with flushing quantity of 0.3 L/min, stand-off distance of 300 μm, the 3D micro-structures with 5 μm dimensional error were machined in 304# stainless steel by applying 3D micro-electrodes in micro-EDM, which had good processing efficiency and processing accuracy. [ABSTRACT FROM AUTHOR]

Different manufacturers do not produce the same quality of children's Ca–Fe–Zn oral liquid due to different production materials and processes. To improve the phenomenon of counterfeit and imitation oral liquid on the market and effectively monitor its quality, laser-induced breakdown spectroscopy (LIBS) fingerprinting with sample preparation methods can provide a tool for real-time and rapid detection of oral liquids. The sample preparation methods include filter paper adsorption (FPA), filter paper adsorption with elemental Cu (FPA with Cu), adding dropwise to glass slides (ADS), adding dropwise to glass slides with elemental Cu (ADS with Cu), and gel preparation (GP). This work collected LIBS spectrum of oral liquids from eight manufacturers. The model for eXtreme Gradient Boosting (XGBoost) was constructed for classifying oral liquids based on five sample preparation methods. The accuracy was 91.25, 94.17, 55.42, 91.25, and 91.29%, respectively. The results show that the FPA method is more straightforward, efficient, and less affected by the specificity of the color of the sample. Both ADS and GP are susceptible to the color characteristics of the sample and are not well suited to the direct detection of transparent liquids. This work demonstrated that oral liquids could be discriminated by analyzing LIBS spectrum combined with the XGBoost model. Additionally, sample preparation, like the simple FPA method, can improve the accuracy of LIBS classification. [ABSTRACT FROM AUTHOR]

Soil samples from wild solid waste dumpsites were collected in the Bijeljina-Zvornik region (Republic of Srpska, Bosnia and Herzegovina), and the concentrations potentionally toxic metals (Ni, Cr, Mn, Zn, Cu, Pb, Cd, Fe and Al). The disposal of waste at wild dumpsites has emerged as a serious environmental challenge affecting both developed and developing countries. This paper aims to provide an in-depth analysis of the complex issue of wild dumpsites, focusing on the contamination of the environment with toxic metals. The improper disposal of solid waste has become a global concern, with wild dumpsites being a significant component of the problem. In accordance with national legislation, the mean values for Cd and Ni exceeded the limit values. Very strong positive correlations are observed between Zn and Cu, between Cd and Pb and between Ni and Cr. The ecological risk assessments for Mn are extremely high; for Ni and Pb, they are high; for Zn, Cu and Cr, they are appreciable; and for Cd, they are moderate. The Pollution Load Index (PLI) and Contamination Factor were used to evaluate metal pollution in soil samples. PLI values exceeding 1.0 in five samples signify soil pollution, supported by mean values indicating contamination. Research findings reveal different contamination levels, with Pb, Cr, Cu, and Zn at low levels, and Ni and Cd at moderate levels. The visualized results of ecological risk assessments for heavy metals in the soil underscore the critical importance of continuous monitoring and effective management of heavy metals at illegal dumpsites to preserve and protect surrounding ecosystems. The use of Surfer 12 software and the kriging method has proven to be an invaluable tool for exploring the spatial distribution of toxic metals in the study area. [ABSTRACT FROM AUTHOR]

The recent multi-analytical study carried out on the Van Eyck's Ghent Altarpiece showed the simultaneous presence of several kinds of metal carboxylates in oil-rich glaze layers. This outcome raised the question whether these carboxylates had already formed during the preparation of the oil binder by the artists. In the case of early-stage formation, they may have had an impact on the drying rate of the resulting oil, as well as on its handling properties. This hypothesis was investigated using a model system of in-house-prepared linseed oil containing incremental concentrations (2–5–10 wt.%) of relevant metal carboxylates (i.e. Ca-, Zn-, Cu-, and Pb oleates and stearates). This paper describes the influence of these type of molecules on the drying rate of linseed oil and, to an extent, on its viscosity. The drying time of the linseed oil, to which one or more metal carboxylates were added, was measured with a drying recorder while the viscosity was assessed with a rheometer. When introduced together, some of these metal carboxylates act in synergy to shorten the drying time with respect to the situation when the same metal carboxylates were added separately to linseed oil. Mixtures of Ca- and Zn-oleates proved to have a larger effect than other binary combinations. Addition of two metal oleates (combination of Ca/Zn/Cu/Pb) reduced the drying time even more. On the other hand, specific combinations of three metal stearates and/or oleates also demonstrated a significant synergistic effect towards increasing the viscosity of the binder. Especially combinations of Ca/Zn/Cu and Ca/Zn/Pb stearates and oleates gave rise to the highest level of linseed oil viscosity increase, when compared to the situation in which the same metal carboxylates were added separately. [ABSTRACT FROM AUTHOR]

The concept, performance, and analyses of distinctive, miniaturized metamaterial (MTM) unit cell addressing the forthcoming Sub 6 GHz 5G applications are presented in this paper. Two circular split-ring resonators (CSRR) with two parallel rectangular copper elements in front of the design and a slotted square element in the background make up the suggested metamaterial. It has a line segment with tunable features that is positioned in the center of the little ring copper structure. The suggested design offers a significant operating frequency band of 220 MHz together with a resonance of transmission coefficient S21 at 3.5 GHz. Furthermore, in two (z & x) principal axes of wave propagation, wide-range achievement, single/double-negative (S/DNG) refractive index, negative permittivity, and near-zero permeability properties were demonstrated. Through varying central slotted-strip line length, resonance frequencies can be selectively altered. Moreover, the metamaterial has overall dimensions of 9 × 9 mm2 and is composed on a Rogers 5880 RT substrate. In order to create the suggested MTM's equivalent circuit, which shows similar coefficient of transmission (S21), a proposed design's numerical simulation is carried out in the CST micro-wave studio. This simulation is after that put to comparison with manufacturing of the design. [ABSTRACT FROM AUTHOR]

This article investigates the impact of metal-organic frameworks (MOFs) on the performance and stability of perovskite solar cells (PSCs), specifically focusing on the type of metal and the morphology of the MOF. Two types of MOFs, copper-benzene-1,3,5-tricarboxylate (Cu-BTC MOF) with spherical morphology and cobalt-benzene-1,3,5-tricarboxylate (Co-BTC MOF) with rod morphology, are synthesized and spin-coated on TiO2 substrates to form FTO/TiO2/MOF/CH3NH3PbI3/C-paste PSCs. The morphology and size of the MOFs are characterized by scanning electron microscopy (SEM), and the crystallinity and residual PbI2 of the perovskite films are analyzed by X-ray diffraction (XRD). The results show that the Co-BTC MOF PSC exhibits the highest power conversion efficiency (PCE) of 10.4% and the best stability, retaining 82% of its initial PCE after 264 h of storage in ambient air. The improved performance and stability are attributed to the enhanced crystallinity and reduced residual PbI2 of the perovskite film after Co-BTC MOF modification. The paper showcases the immense potential of MOF-based interlayers to revolutionize PSC technology, offering a path toward next-generation solar cells with enhanced performance and longevity. [ABSTRACT FROM AUTHOR]

The regulation of hydrogen content in the continuous casting process is conducive to the reduction of pore defects in the casting billet. In this paper, the influence of negative pressure (NP) and continuous casting speed (CCS) on hydrogen content in copper rod billet prepared by negative pressure continuous casting (NPCC) technique was analyzed, and the mechanism of the coordinated coupling of NP and melt flow on hydrogen removal was revealed. It is clarified that with the CCS of 20 mm min−1 and an increase in the NP value from − 20 to − 80 kPa, the hydrogen content is reduced from 1.0 to 0.3 ppm. The coordinated action of NP and melt flow induced by CCS can minimize the hydrogen content. When the NP value is − 80 kPa and the CCS is 10 mm min−1, the hydrogen content is as low as 0.2 ppm, and the hydrogen removal rate is 85.7%. The larger the NP, the smaller the critical nucleation radius of the hydrogen bubble, and the larger the growth rate of the hydrogen bubble. The coupling of the NP field and flow field can make the melt which is difficult to nucleate and grow of the hydrogen bubble flow to the position which is easy to nucleate and grow. The effect of the vortex fields in the purification chamber on the removal of hydrogen is not affected by the CCS, but the CCS affects the floating of hydrogen at the solidification front, which leads to a small increase in the hydrogen content with the increase of the CCS. Our study provides a theoretical basis for the preparation of high-quality metal billets. [ABSTRACT FROM AUTHOR]

In this paper, high-density (60−x)Fe−Cr−Co−xCu (x: 0–6 wt.%) permanent magnet alloys were fabricated by laser powder bed fusion (LPBF) in-situ alloying technique, and the effects of Cu content on the microstructure, magnetic, and mechanical properties of the alloy were systematically investigated. The addition of 2 wt.% Cu enhanced the coercivity H c and the energy product (B H) max of the alloy in the isotropic state by 19.4 and 27.9%, respectively, compared to the alloy without Cu. The impacts of Cu content on the magnetic properties were investigated by combining experimental results and first-principles calculations. Furthermore, the addition of Cu improved the yield strength of the alloy, and the strengthening mechanism was analyzed in detail. The yield strength of the alloy with 2 wt.% Cu reached 908 MPa, representing a notable 7% increase relative to the Cu-free alloy. [ABSTRACT FROM AUTHOR]

With the continuous downsizing of solder joints, the influence of the grain characteristics of the under bump metallization (UBMs) on the interfacial reaction is exposed. In this paper, the effect of grain characteristics of Cu UBM on the growth of interfacial intermetallic compounds and the formation of Kirkendall voids in Cu/Sn/Cu micro solder joints during isothermal aging at 150 °C was investigated. Electroplated polycrystalline Cu (EP-Cu), (111) single crystal Cu ((111) Cu), and (111) nano-twinned Cu ((111) nt-Cu) were selected as UBMs. After reflow soldering, the Cu6Sn5 grains formed on (111) nt-Cu were near to the orientation (2 1 - 1 - 3) , while those were randomly formed on both EP-Cu and (111) Cu. During isothermal aging, the Cu6Sn5 grains exhibited the highest growth rate on (111) nt-Cu UBM, and the slowest growth rate on (111) Cu UBM, due to the differing number of diffusion routes among the three Cu UBMs with distinct grain characteristics. Furthermore, no Kirkendall voids were detected on the (111) Cu UBM, however, a significant number of Kirkendall voids were identified on the (111) nt-Cu UBM, which can be attributed to the diffusion path and impurities present in the three Cu UBMs. The results will offer theoretical and practical recommendations for the selection of Cu UBMs for micro solder joints in 3D packaging interconnection technology. [ABSTRACT FROM AUTHOR]

Context: Herein, we compare and contrast the dual roles of Cun clusters (n = 3, 5, and 7 atoms) in scavenging or generating RO• free radicals from ROH at the theoretical levels (where R = H, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, and phenyl). This investigation is performed in water media to mimic the actual environment in the biological system. In the presence of the Cun clusters, bond dissociation energy (BDE) of RO–H and R–OH is reduced. This is clear evidence for the increased possibility of both the RO–H and R–OH bonds breakage and scavenging of RO• radicals. The nature of anchoring bonds responsible for the interaction of Cun clusters with ROH and RO• are interpreted using the quantum theory of atoms in molecules (QTAIM) and the natural bond orbital (NBO) analysis. The DFT results indicate that the O•⋅⋅⋅•Cu bond is stronger and has more covalent character in RO•⋅⋅⋅•Cun radical complexes than in ROH⋅⋅⋅•Cun. Therefore, the interactions of Cun clusters with RO• radicals (antioxidant) are more pronounced than their interactions with ROH non-radicals (pro-oxidant). Methods: The GAMESS software package was utilized in this paper. The B3LYP and M06 functions with the 6–311 + + G(d,p), and LANL2DZ/SDD basis sets was used to perform the important geometrical parameters of RO•⋅⋅⋅•Cun and ROH⋅⋅⋅•Cun, binding energy (Eb), and bond dissociation energy (BDE). [ABSTRACT FROM AUTHOR]

Non-thermal plasma (NTP) is a well-known decontamination tool applicable for a wide range of microorganisms and viruses. Since the recent COVID-19 pandemic highlighted the need to decontaminate all daily used items, it is highly desirable to address the applicability of NTP, including its possible harmful effects. To the best of our knowledge, a comprehensive characterization of NTP effects on sensitive materials is still lacking. We investigated the potential damage to common materials of daily use inflicted by air atmospheric NTP generated in Plasmatico v1.0. The materials tested were paper, various metals, and passive and active electronic components modelling sensitive parts of commonly used small electronic devices. The NTP-exposed paper remained fully usable with only slight changes in its properties, such as whitening, pH change, and degree of polymerization. NTP caused mild oxidation of copper, tinned copper, brass, and a very mild oxidation of stainless steel. However, these changes do not affect the normal functionality of these materials. No significant changes were observed for passive electronic components; active components displayed a very slight shift of the measured values observed for the humidity sensor. In conclusion, NTP can be considered a gentle tool suitable for decontamination of various sensitive materials. [ABSTRACT FROM AUTHOR]

This paper presents the results of the first X-ray fluorescence (XRF) investigation conducted on three late medieval chalices associated with Ireland: the Ó Learghusa chalice, auctioned as medieval Irish in 2021, does not have a confirmed provenance; the de Burgo-O'Malley chalice, dated 1494, and the TP-IEP chalice, dated 1589, both of Irish provenance. This study effectively addressed the knowledge gap concerning Irish medieval silver chalices composition. The analysis revealed that both the Ó Learghusa and de Burgo-O'Malley chalices were crafted from a silver-copper alloy and adorned using a fire-gilding technique. The blue and green enamels on the de Burgo-O'Malley chalice were found to be constituted by cobalt and iron/copper glasses, respectively. In contrast, the TP-IEP chalice exhibited a more intricate structure, being a composite object with partial silver gilt and with the bowl and base possibly made of a ternary silver-copper-gold alloy. The TP-IEP chalice's knop displayed glass, simulating gems with transparent, blue, and purple colorations. XRF analysis allowed identification of lead-potash glass, while the red glass displayed a rich iron content and was identified as soda-lime glass. The analysis allowed concluding that the de Burgo-O'Malley chalice had retained its original condition, including its original gilding and enamels, while the Ó Learghusa and TP-IEP chalices appeared to have undergone refurbishment. These significant discoveries contribute to a deeper understanding of the historical context and artistic craftsmanship behind these late medieval chalices, shedding light on their unique stories within Irish art and history. [ABSTRACT FROM AUTHOR]

Solar-driven interfacial evaporation is a sustainable and green desalination method with great prospects for development in today's severe water shortage problem. In this paper, a novel composite aerogel was prepared by hydrothermal method with sodium alginate (SA) and Cu2+ in the preparation process using reduced graphene oxide as photothermal material and cellulose nanofibers as substrate. The good hydrophilicity of nanocellulose makes the composite aerogel have strong capillary action and continuous water transport. The gel formed by ion exchange between SA and Cu2+ greatly improves dry and wet mechanical strength of the composite aerogel and ensures the stability of the evaporator for multiple recycling. Copper is doped by reduction of copper ion complexes and reduced graphene oxide have a synergistic effect to increase the photothermal response rate of the composite aerogel of 1.446 kg m−2 h−1 with evaporation efficiency of 84.87% under one standard solar irradiation. In addition, the purification of heavy metal ions, dye wastewater as well as acid and alkali solutions also has excellent results. It is expected that this study will provide some new ideas for the fields of seawater desalination and wastewater treatment. [ABSTRACT FROM AUTHOR]

Background: Stress measurement for thin films is crucial in a variety of fields such as in semiconductor manufacturing, the optoelectronics industry, and biomedical science, among others. However, most measurement methods require surface treatment of the thin film. Objective: A label-free measurement method for plane stress states in optical isotropic thin films based on spectroscopic ellipsometry analysis is proposed and verified in this paper. Methods: The proposed method is based on the modulation of the stress-optic effect on reflected spectroscopic ellipsometry. A theoretical model is established to describe the relation between all components of the plane-stress state and the classic ellipsometric parameters (Ψ, Δ). An algorithm is developed to determine all components of a plane-stress state by fitting the model to the experiment data. Results: In the verification experiment, we determined the plane stress state of a Cu film coated on a PI (polyimide) substrate. The results show a reasonable agreement between the experimental measurements from spectroscopic ellipsometry and the theoretical analysis based on the applied loading. Conclusion: The results prove that our method can effectively measure the plane stress state of optical isotropic thin films. [ABSTRACT FROM AUTHOR]

Rare earth additives have an important influence on the quality of the deposited layer and the electric crystallization behavior during metal electrodeposition. In this paper, linear scanning voltammetry (LSV), cyclic voltammetry (CV), and chronoamperometry (CA) were used to investigate the effects of different concentrations (0 –1.0 g·L−1) of cerium chloride additives on the electric crystallization behavior of copper electrodeposited by industrial electrolytes. The microscopic morphology, grain size, and preferred orientation of copper deposition layers obtained from Harlem tank experiments were analyzed by scanning electron microscopy and X-ray diffraction to investigate the effect of cerium chloride on the grain refinement and crystal growth orientation of copper deposition layers in industrial electrolysis. The results show that: When cerium chloride was added into industrial electrolyte, the copper deposition potential shifted negatively, the cathode polarization increased, the nucleation relaxation time decreased, the nucleation rate of copper increased, and the grain was refined. However, the addition of cerium chloride did not change the nucleation/growth mechanism of copper, which is still three-dimensional instantaneous nucleation. When the concentration of cerium chloride is 0.4 g·L−1, the cathodic polarization was the largest, the nucleation relaxation time was the shortest, and the deposited layer grains were the smallest. Moreover, the preferred orientation of the deposited layer is changed from (220) to (220) and (222) to double preferred, thus suppressing grain growth and uniform grain distribution of the deposited layer. Therefore, 0.4 g·L−1 is the optimum concentration of cerium chloride to be added. [ABSTRACT FROM AUTHOR]

In this paper, we have proposed the precise model of coaxial TGVs (CTGVs) which consists of ground-signal signal-ground (GSSG) TGVs. An equivalent electrical model of CTGVs is established and the partial element equivalent circuit (PEEC) technique is used to extract the frequency-dependent impedance parameters. In CTGVs, multi-walled carbon nanotubes (MWCNT) and copper is used as filler material in inner and outer layer. Resistance and inductance of CTGVs is calculated using the PEEC technique for different filler materials. The insertion loss (S21) of CTGVs is determined using the HFSS simulations and is compared analytically in differential mode configurations. S21 is calculated for various geometrical parameters of MWCNT-based CTGVs such as diameter of TGV, pitch between CTGV pair, as well as material properties such as permittivity of SiO2 and benzocyclobutene (BCB) polymers. It is established that MWCNT based CTGV shows improved insertion loss because the conductivity of MWCNT is higher in comparison to copper. [ABSTRACT FROM AUTHOR]

The demolding process of electroforming technology in fabricating microstructured optical-functional thin films produces the problem of excessive bonding between the metal substrate and the metal replica, which triggers the deformation of the microstructure and the reduction of precision, and the deposition of Cr–O–C discrete nuclei at the interface can play a good role in assisting the demolding effect. In this paper, the tensile deformation of polycrystalline Cu/Ni and Cu/Cr–O–C/Ni composites is investigated using molecular dynamics methods. The results show that the Cu/Ni model produces a large number of HCP structures during stretching, with holes at the interface and a large number of Cu atoms transferring to the Ni layer. The addition of the Cr–O–C layer reduces the yield strength of the Cu/Cr–O–C/Ni model by 26.41%, and at the same time, the dislocation proliferation at the interface is reduced, and the fracture is at the centralized interface, and the fracture time is reduced by 90.8%. The higher number of Cr–O–C atoms at the interface decreases the transfer of Cu atoms to the Ni layer. The results provide a possible explanation for the Cr–O–C layer-assisted precision electrodeposition debonding. [ABSTRACT FROM AUTHOR]

In this paper, the reliability of copper pillar micro-bump under random vibration is investigated. Three kinds of copper pillar solder joints with different morphologies were obtained by changing the hot press bonding process, and the random vibration fatigue simulation of flip-flop interconnect solder joints was carried out by using Ansys to obtain the stress–strain distribution law of the solder joints and predict the vibration fatigue life of the solder joints. It is found that the outermost solder joints of flip-flop bonding are most likely to fail; the fatigue life of copper pillar solder joints is predicted based on the three interval method, the Miner linear cumulative damage criterion and the high cycle fatigue formula; reliability experiments are conducted, and it is found that the drum solder joints are most prone to cracking, followed by hourglass and columnar shapes and that all cracks are caused by the substrate side of copper pillar. Cracks are sprouted from the contact surface between the copper pillar and solder on the substrate side and expand internally in the intermetallic compound (IMC) layer, while the presence of voids aggravates the generation of cracks. [ABSTRACT FROM AUTHOR]

Non-thermal plasma (NTP) is a well-known decontamination tool applicable for a wide range of microorganisms and viruses. Since the recent COVID-19 pandemic highlighted the need to decontaminate all daily used items, it is highly desirable to address the applicability of NTP, including its possible harmful effects. To the best of our knowledge, a comprehensive characterization of NTP effects on sensitive materials is still lacking. We investigated the potential damage to common materials of daily use inflicted by air atmospheric NTP generated in Plasmatico v1.0. The materials tested were paper, various metals, and passive and active electronic components modelling sensitive parts of commonly used small electronic devices. The NTP-exposed paper remained fully usable with only slight changes in its properties, such as whitening, pH change, and degree of polymerization. NTP caused mild oxidation of copper, tinned copper, brass, and a very mild oxidation of stainless steel. However, these changes do not affect the normal functionality of these materials. No significant changes were observed for passive electronic components; active components displayed a very slight shift of the measured values observed for the humidity sensor. In conclusion, NTP can be considered a gentle tool suitable for decontamination of various sensitive materials. [ABSTRACT FROM AUTHOR]

The extensive usage and production of copper may lead to toxic effects in organisms due to its accumulation in the environment. Traditional methods for copper detection are time consuming and infeasible for field usage. It is necessary to discover a real-time, rapid and economical method for detecting copper to ensure human health and environmental safety. Here we developed a colorimetric paper strip method and optimized spectrum method for rapid detection of copper ion based on the specific copper chelator bathocuproinedisulfonic acid disodium salt (BCS). Both biological assays and chemical methods verified the specificity of BCS for copper. The optimized reaction conditions were 50 mM Tris–HCl pH 7.4, 200 µM BCS, 1 mM ascorbate and less than 50 µM copper. The detection limit of the copper paper strip test was 0.5 mg/L by direct visual observation and the detection time was less than 1 min. The detection results of grape, peach, apple, spinach and cabbage by the optimized spectrum method were 0.91 μg/g, 0.87 μg/g, 0.19 μg/g, 1.37 μg/g and 0.39 μg/g, respectively. The paper strip assays showed that the copper contents of grape, peach, apple, spinach and cabbage were 0.8 mg/L, 0.9 mg/L, 0.2 mg/L, 1.3 mg/L and 0.5 mg/L, respectively. These results correlated well with those determined by inductively coupled plasma-mass spectrometry (ICP-MS). The visual detection limit of the paper strip based on Cu-BCS-AgNPs was 0.06 mg/L. Our study demonstrates the potential for on-site, rapid and cost-effective copper monitoring of foods and the environment. [ABSTRACT FROM AUTHOR]

The dielectric loss of Cu with high thermal conductivity is large at high frequency, which cannot meet the performance requirements in high-integrated circuits. There is an urgent need for materials to reduce its dielectric loss. In this paper, the thermal conductivity and dielectric properties of the AlN coating-Cu substrate system were controlled by changing the N2 pressure. The results showed that the crystallinity of hcp-AlN in AlN coating increased significantly when the proportion of N2 pressure was increased. With the increase of the N2 pressure, the particle size on the surface and the roughness of the coating improved. The AlN coating prepared at high N2 pressure had high dielectric constant and low dielectric loss at high frequency compared to those of the coatings prepared at low N2 pressure. At the same time, the AlN coating prepared under high N2 pressure on the Cu substrate did not decrease the thermal conductivity of Cu substrate. The AlN-Cu system prepared in this paper had high thermal conductivity and good dielectric properties, providing theoretical guidance for integrated circuit packaging and capacitor applications. [ABSTRACT FROM AUTHOR]

The demand for micro-components continues to increase, and there is a constant trend towards miniaturization and complexity. The traditional forming process micromachining technology has disadvantages such as high cost, complex manufacturing process, and long cycle, which cannot meet the needs of the industrial development. A new micro-forming process of metal foil arrays based on submerged cavitation water jets is proposed in this paper, and the shapes of the mold grooves are selected as triangular, quadrilateral, pentagonal, and hexagonal. The micro-jet and shock wave generated by the collapse of the cavitation in the submerged cavitation jet is used as the force-loading method of the foil to complete the flexible array micro-forming of the metal foil in this process. The results show that: the flow field at different incident pressures has low pressure and low pressure action time, fully satisfying the conditions required for cavitation to occur; the flooded cavitation water jet is concentrated in the downstream collapse area as a ring-shaped area; the more the number of single hole sides of the mold, the lower the deformation resistance in each area of the T2 Cu foil, and the clearer the T2 Cu foil forming profile. The submerged cavitation water jet array micro-forming studied in this paper is a low-cost, green, high-efficiency, and highly applicable forming process, which is a beneficial exploration and attempt at a new type of foil array micro-forming, which has high research value and good application prospects. [ABSTRACT FROM AUTHOR]

Detonation spraying is commonly used to form protective and functional coatings. The influence of the temperature and velocity of spraying particles on the quality of the coatings is frequently analyzed by the study of single splats. However, to date, there has been limited research on the interaction and structure formation at the splat/substrate interface during detonation spraying. In this paper, copper splats and coatings were formed on steel substrates using three different spraying modes: 'cold', 'normal', and 'hot'. The features of the particle/substrate interaction were studied experimentally and by numerical simulation using the smoothed particle hydrodynamics (SPH) method. The simulation revealed the deformation and temperature history of the particles and substrate during impact. The structure of the splats and coatings was characterized using scanning electron microscopy (SEM) and synchrotron X-ray diffraction (SXRD). The microstructure of the coatings sprayed in the 'normal' and 'hot' modes consists of columnar crystals, indicating complete melting of the particles. The coating obtained in the 'cold' mode consists of a mixture of molten, partially molten, and unmolten particles. SXRD analysis revealed an increase in dislocation density in the sprayed coatings compared to the initial powder. The sprayed material mainly contains screw dislocations, while the initial powder predominantly contains edge dislocations. The approach used, combining materials characterization techniques and numerical simulation, has great potential for analyzing the coating formation process and can be applied to the optimization of thermal spraying parameters of various materials. The results of this study may be of interest to other researchers working in the field of thermal spraying of copper-based alloys. [ABSTRACT FROM AUTHOR]

An urgent environmental problem in the Perm region is the increased concentration of some heavy metals in soils. This paper presents the results of studying the ecological and geochemical role of the magnetic fraction of soils in the Middle Cis-Urals. The study used magnetometry, geostatistical and geochemistry methods. It has been established that the magnetic fraction is a geochemical barrier in soils and accumulates potentially toxic elements (Mn, Ni, Cu, Co, and Pb). The total content of Mn, Zn, Ni, Cu, Co, and Pb in the soils of the agricultural landscapes of the taiga-forest zone of the Middle Cis-Urals exceeds the clarke of world soils. The ecological-magnetic subprofile of the studied soils is subdivided into ecological-magnetic layers: accumulation, destruction, and stable state of magnetic particles. The environmental organizations of the Perm region are recommended to use methods of ecological magnetism for carrying out soil-ecological monitoring and identifying land contaminated with heavy metals. The obtained information about the elemental chemical composition of soils of the Middle Cis-Urals can be used in the management of land resources and the development of the concept of land policy in the region. [ABSTRACT FROM AUTHOR]

Herein, we systematically studied the thermodynamic and kinetic aspects of glass forming compositions in Ca–Mg–Cu alloy obtained by drawing the isocontour. Parameter derived from the enthalpy of chemical mixing (ΔHchem) and normalized mismatch entropy () is used as a glass-forming ability (GFA) parameter. Variation of with reported and calculated compositions is evaluated. Linear relation of Cu with is observed, whereas inverse relation of Ca and Mg is obtained. The linear variation of with a supercooled liquid region (SCLR) () is studied. Inverse correlation of critical cooling rate () with is obtained. for predicted compositions is found close to that of reported compositions. Therefore, Cu should be added carefully with other elements to improve the GFA and reduce the cooling rate of Ca‒Mg‒Cu glassy. In this paper, an empirical correlation of with is proposed, and the modeled values are found to agree with the experimental values. [ABSTRACT FROM AUTHOR]

Additives are a cost-effective method to improve the performance of the very low profile (HVLP) copper foil coarsened layer. In this paper, the effects of 3,3'-Dithiobis-1-propanesulfonic acid disodium salt (SPS), gelatin, and sodium thiazoline dithiopropane sulfonate (SH110) concentration on the morphology, roughness, and peel strength of HVLP copper foil was reported. The results show that SH110 contributes significantly to the reduction of copper foil roughness, improvement of peel strength, and refinement of coarsened layer grains. In addition, the linear scanning voltammetry and AC impedance spectroscopy of the solution were carried out to understand the action mechanism of additives on the copper foil surface. The results demonstrate that SPS promotes the copper deposition process due to the presence of sulfonic acid groups(–SO3). The amino group(–NH2) of gelatin inhibits copper deposition. SH110 has both promoter (Sodium 3-Mercapto-1-Propane Sulfonate, MPS) and inhibitor (Tetrahydrothiazolidinone, H1) fragments, which achieve synergistic or competitive effects consistent with the composite additive. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of a novel Cu–Ni bimetallic system comprising of magnetic nanoparticles, as the core, and 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (4-ABPT), as a conjugated bridge, between nickel and copper species. With low Cu and Ni loading (0.06 mol% Ni, 0.08 mol% Cu), the resulting Fe3O4@SiO2@4-ABPT/Cu–Ni showed to be a highly efficient catalyst for the Sonogashira and C–N cross-coupling reactions. The developed catalyst was well characterized by FT-IR, XRD, EDX-mapping, FE-SEM, TEM, ICP, VSM, TGA/DTG/DTA, LSV, and XPS techniques. Fe3O4@SiO2@4-ABPT/Cu–Ni nanocatalyst was compatible with a wide range of amines and aryl halides in the Sonogashira and C–N cross-coupling reactions and offered desired coupling products in high to excellent yields under palladium- and solvent-free conditions. Based on the XPS results, the 4-ABPT ligand can adjust electron transfer between Ni and Cu in Fe3O4@SiO2@4-ABPT/Cu–Ni, promoting the formation and stabilization of Cu+ and Ni3+ species. Electronic interactions and the synergistic effect between these metals increased the selectivity and activity of Fe3O4@SiO2@4-ABPT/Cu–Ni catalyst in the Sonogashira and C–N cross-coupling reactions compared with its monometallic counterparts. Additionally, the magnetic properties of Fe3O4@SiO2@4-ABPT/Cu–Ni facilitated its separation from the reaction mixture, promoting its reuse for several times with no significant loss in its catalytic activity or performance. [ABSTRACT FROM AUTHOR]

In this paper, we examine the impact of the circular economy on global resource extraction. To this end, we make an input–output analysis dynamic by combining it with an agent-based model of the capital sector. This approach allows us to study the evolution of the circular economy due to the endogenous decisions of firms on whether to invest in the capital expansion of primary or secondary sectors. Previous studies have examined the macroeconomic effects of the circular economy using scenarios that exogenously impose higher recycling rates, improved resource efficiency, or lowered demand on the economy. Such studies typically assume static consumer budgets, no price adjustments, capital investments in recycling infrastructure, or technological innovation. We relax these assumptions in a novel agent-based input–output model (ABM-IO). We show that the circular economy can significantly reduce the extraction of iron, aluminum, and nonferrous metals if implemented globally. However, the leakage effect may also cause some metal-intensive industries to relocate outside the EU, offsetting the circular economy efforts. The risk of the leakage effect is especially high for copper. [ABSTRACT FROM AUTHOR]

In the process of double-shield TBM excavation, it is difficult to directly observe and test the characteristics of the surrounding rock. In this paper, the screening test of the different type tailings in the wet state was carried out to obtain the gradation curve and curve evaluation index. Combining with the excavation parameters and the surrounding rock characteristics of the tailings, a comprehensive analysis was carried out to establish the evaluation system among with the tailings gradation characteristics, lithology characteristics and excavation parameters. The results showed that: Sparsely fissured rock: the tailings are extensional fractures, the tailings gradation curve is inverse "S" type and gentle, and the evaluation index value: (1.50 > lg(Cu) > 1.35), (1.90 > Cc > 1.10). Broken surrounding rock: the curve is "L" type and steep, the content of coarse particles is much more than that of fine particles and (1.10 > lg(Cu) > 1.00), (2.60 > Cc > 2.40). Fractured rock: the curve is "Step" type, the tailings particles lack the middle particle size, the minerals are mostly weathered, (2.15 > lg(Cu)> 1.95), (0.09 > Cc > 0.07). The research results have good applicability to the surrounding rock stability evaluation of the example tunnel, which verifies the feasibility of the method. [ABSTRACT FROM AUTHOR]

This paper deals with the evaluation of novel imidazole molecules for their antimicrobial and larvicidal activities. A series of imidazole derivatives 1(a–f) and 2(a–e) were prepared by the Mannich base technique using a Cu(II) catalyst. The Cu(phen)Cl2 catalyst was found to be more effective than other methods. FTIR, elemental analyses, mass spectrometry, 1H NMR, and 13C NMR spectroscopy were performed to elucidate the structures of the synthesised compounds. Antimicrobial and larvicidal activities were investigated for all compounds. The antibacterial activity of compounds (2d) and (2a) were highly active in S.aureus (MIC: 0.25 μg/mL) and K.pneumoniae (MIC: 0.25 μg/mL) compared to ciprofloxacin. Compound (1c) was significantly more effective than clotrimazole in C.albicans (MIC: 0.25 μg/mL). Molecular docking studies of compound 2d showed a higher binding affinity for the 1BDD protein (− 3.4 kcal/mol) than ciprofloxacin (− 4.4 kcal/mol). Compound 1c had a higher binding affinity (− 6.0 kcal/mol) than clotrimazole (− 3.1 kcal/mol) with greater frontier molecular orbital energy and reactivity properties of compound 1c (∆E gap = 0.13 eV). The activity of compound 1a (LD50: 34.9 μg/mL) was more effective in the Culex quinquefasciatus than permethrin (LD50: 35.4 μg/mL) and its molecular docking binding affinity for 3OGN protein (− 6.1 kcal/mol). These newly synthesised compounds can act as lead molecules for the development of larvicides and antibiotic agents. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of a novel Cu–Ni bimetallic system comprising of magnetic nanoparticles, as the core, and 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (4-ABPT), as a conjugated bridge, between nickel and copper species. With low Cu and Ni loading (0.06 mol% Ni, 0.08 mol% Cu), the resulting Fe3O4@SiO2@4-ABPT/Cu–Ni showed to be a highly efficient catalyst for the Sonogashira and C–N cross-coupling reactions. The developed catalyst was well characterized by FT-IR, XRD, EDX-mapping, FE-SEM, TEM, ICP, VSM, TGA/DTG/DTA, LSV, and XPS techniques. Fe3O4@SiO2@4-ABPT/Cu–Ni nanocatalyst was compatible with a wide range of amines and aryl halides in the Sonogashira and C–N cross-coupling reactions and offered desired coupling products in high to excellent yields under palladium- and solvent-free conditions. Based on the XPS results, the 4-ABPT ligand can adjust electron transfer between Ni and Cu in Fe3O4@SiO2@4-ABPT/Cu–Ni, promoting the formation and stabilization of Cu+ and Ni3+ species. Electronic interactions and the synergistic effect between these metals increased the selectivity and activity of Fe3O4@SiO2@4-ABPT/Cu–Ni catalyst in the Sonogashira and C–N cross-coupling reactions compared with its monometallic counterparts. Additionally, the magnetic properties of Fe3O4@SiO2@4-ABPT/Cu–Ni facilitated its separation from the reaction mixture, promoting its reuse for several times with no significant loss in its catalytic activity or performance. [ABSTRACT FROM AUTHOR]

In this paper, we examine the impact of the circular economy on global resource extraction. To this end, we make an input–output analysis dynamic by combining it with an agent-based model of the capital sector. This approach allows us to study the evolution of the circular economy due to the endogenous decisions of firms on whether to invest in the capital expansion of primary or secondary sectors. Previous studies have examined the macroeconomic effects of the circular economy using scenarios that exogenously impose higher recycling rates, improved resource efficiency, or lowered demand on the economy. Such studies typically assume static consumer budgets, no price adjustments, capital investments in recycling infrastructure, or technological innovation. We relax these assumptions in a novel agent-based input–output model (ABM-IO). We show that the circular economy can significantly reduce the extraction of iron, aluminum, and nonferrous metals if implemented globally. However, the leakage effect may also cause some metal-intensive industries to relocate outside the EU, offsetting the circular economy efforts. The risk of the leakage effect is especially high for copper. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the impact of plastic deformation using hydrostatic extrusion (HE) on the structural, mechanical and functional properties of pure copper for use as electrodes in the process of electro discharge machining (EDM). As part of the research, copper was subjected to the HE process with the maximum cumulative true strain equal to ɛcum = 3.89 obtained in 5 stages. The result was, a refinement of the microstructure with the grains elongated in the direction of extrusion, with a cross-sectional size of d2 = 228 nm. As the obtained material can be potentially used in the process of electro discharge machining, the copper specimens after the HE process were subjected to a comprehensive analysis to determine the mechanical, physical and functional properties of the material. A significant increase in strength (UTS) and yield strength (YS) of the HE-processed copper was obtained, reaching respectively UTS = 464 MPa and YS = 456 MPa at the maximum strain of ɛ = 3.89. Despite the clear strain-induced strengthening of the material, a very high electrical conductivity of not less than 97% was obtained. The electrodes made of copper after HE process have reduced erosion wear while maintaining a comparable or better quality of the machined surface. The best results were obtained for finish machining, where the electrical discharge wear was lower by 60% compared to the electrode made of non-processed copper. In addition, an improvement in the surface quality after the EDM process by 25% was observed when using the HE-processed electrodes. [ABSTRACT FROM AUTHOR]

In this paper, we report a theoretical study of the electronic structure of copper oxides. The band structure of the copper oxides Cu2O and CuO has been calculated in the density functional approach by the full-potential linearized augmented plane wave method, using the modified Becke–Johnson (mBJ) potential. The results demonstrate that the use of the modified Becke–Johnson potential ensures better agreement of band structure calculation results for the copper oxides with experimental data then does the generalized gradient approximation (GGA). The use of the mBJ potential allows both compounds to be described as semiconductors whose band structure parameters are in qualitative agreement with experimental data. We have calculated copper L3-edge and oxygen K-edge X-ray absorption near edge structure spectra of Cu2O and CuO at different occupancies of the core level from which an electron transition occurs and compared the calculation results with experimental data. [ABSTRACT FROM AUTHOR]

In this paper, PTFE/Cu composite material for liner is taken as the research object, and the preparation process and jet forming characteristics of PTFE/Cu composite liner are studied. The liners were prepared by extrusion molding, molded sintering and hot-pressing sintering. Due to different preparation processes, different microstructures of the liner can occur, including defects such as pores and microcracks, resulting in different strength and density of the liner, leading to differences in the forming characteristics of the jet. Therefore, the forming process of the jet was simulated by the finite element numerical simulation software. It was found that there was obvious radial expansion effect in the head of the jet, but with the increase of density, the radial expansion effect was weakened, and the jet velocity decreased gradually. The strength and densification of the shaped charge liner prepared by different processes were different. The densification of the molded sintering liner was generally better than that of the other two kinds of shaped charge liners. As a result, the velocity of the jet formed by the molded sintering liner is always the highest, with a numerical simulation velocity of 6642 m/s and an experimental velocity of 6534.7 m/s. The second is the jet of the hot-pressing sintering liner and the lowest velocity is the jet of the extrusion molding cover, with a numerical simulation velocity of 6482 m/s, while the experimental velocity is only 6397.9 m/s. The jet velocity measured by the pulse X-ray experiment was compared with the velocity of the numerical simulation, and the error was within 2.96%, which verifies the accuracy of the numerical simulation. [ABSTRACT FROM AUTHOR]

Background: Accurate measurements of material constitutive model parameters are of great significance for design optimization and reliability analysis. Objective: In this paper, to characterize the anisotropic elastoplastic parameters of single-crystal metal materials at the nanoscale, a high-throughput inversion method of anisotropic elastoplastic constitutive parameters of single-crystal metal materials using a neural network and bicrystalline indentation load-depth curve is proposed. It addresses the limitations of indentation technology in the characterization of anisotropic material parameters. Methods: A large number of finite-element simulation results were used to build a sample dataset. A neural network was used to build a mapping relationship model between the characteristics of the indentation load-depth curve and the parameters of the material elastic–plastic constitutive model. Results: The parameter inversion method based on the neural network reduced the iterative optimization link, improved the parameter inversion efficiency, and realized high-throughput parameter inversion of the nonupdated intelligent material constitutive model. Conclusion: The effectiveness of the method was verified by inversion experiments of anisotropic elastic–plastic parameters of a single-crystal copper material. The accuracy and universality of the method were further verified by an error analysis, demonstrating the engineering application prospects of the proposed method. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms behind sintering Cu-Ag core–shell nanoparticles can help us optimize the sintering process parameters and design the core–shell structure to achieve the desired sintering structure. In this paper, we employed molecular dynamics simulations to investigate the sintering behaviors and mechanisms of CS NPs, taking into account the effects of shell thickness, particle size, and temperature. Our results revealed that dislocation loops in Cu-Ag CS NPs played a crucial role in sintering by emitting dislocations that facilitated crystal evolution, thereby reducing the number of amorphous structures. The state of dislocation loops could be controlled by shell thickness and NP size. As the shell thickness decreased to 0.5 nm, the structure of the dislocation loops could not be generated due to the extremely chaotic and thin Ag atoms. Furthermore, for NPs of the same size, the CS NP with a 0.5-nm shell thickness was the most active. Despite the neck not consisting of a Cu core, the Cu core, particularly its interface, could still participate in the sintering process. At 900 K, limited interface diffusion could be activated. [ABSTRACT FROM AUTHOR]

The impact of solute Al on the penetration of Cu atoms into the Fe grain boundary (GB) in the Fe–Cu embrittlement system was investigated by performing molecular dynamics simulations. Furthermore, the first principle density functional theory calculation was also employed to determine the binding properties and the electronic structure of GBs doped with solute atoms. The inhibition mechanism of liquid metal embrittlement (LME) cracks in the Fe–Cu system by Al was analyzed at the atomic scale by conducting simulations and calculations. The results show that the diffusion rate of Al along with the GB direction was much higher than that of Cu, and the preferential penetration and segregation of Al atoms acted as a barrier layer. Moreover, the addition of Al reduced the potential energy of Cu atoms, thus stabilizing their motion. These factors significantly inhibited the diffusion of Cu atoms along with the GB direction. The binding property of Fe GB doped with a high concentration of Cu was severely deteriorated, while the Al doping improved the atomic bonding. GBs with higher binding properties are less susceptible to fracture and groove under the application of tensile stress. This paper presents a novel perspective on the inhibition mechanism of LME cracks by doping a third component to inhibit the penetration of embrittlement atoms. [ABSTRACT FROM AUTHOR]

Copper/steel composite is a kind of composite with excellent performance and broad application prospects. In this paper, the micro-morphology and structure of the interface of copper/steel composite prepared by the hot-dip casting were observed by scanning electron microscope and transmission electron microscope, and the formation mechanism of the interface area was explored. The results show that the hot-dip casting temperature has a great influence on the micro-structure and morphology of the copper/steel interface area. When the hot-dip casting temperature is lower than 1125 °C, the copper/steel interface area is basically in a straight line. Even if the hot-dip casting time is extended, the interface characteristics change little. At 1100 °C, the copper-rich phase precipitated at the interface area is the coherent precipitates of Cu and BCC-Fe, with the crystal orientation <110> and the diameter about 10 nm ~ 30 nm. When the hot-dip casting temperature reaches 1150 °C, the copper/steel interface area begins to appear new micro-morphology, and the range of new micro-morphology becomes larger and larger with the increase in the hot-dip casting temperature and the extension of the hot-dip casting time. At 1200 °C, the copper-rich phase precipitated at the interface is the coherent precipitates of FCC-Cu and FCC-Fe, with the crystal orientation <100> and the size similar to that at 1100 °C. In the process of the hot-dip casting, the formation of the copper/steel interface area experienced three stages: the co-temperature of copper/steel and the wetting of copper liquid on solid steel, the formation and transformation of the solid–liquid mixed layer between steel and copper liquid and the evolution stage of the liquid–solid mixed layer during cooling and solidification. This kind of interface zone with gradual structure tightly connects the steel matrix and solidified copper together, to form a copper/steel composite with strong bonding. [ABSTRACT FROM AUTHOR]

In the giant large-scale integrated circuits manufacturing process, chemical mechanical polishing (CMP) for Cu interconnection can lead to chemical corrosion on Cu surface if inhibitors are not added to the CMP slurry. This paper concentrated on the synergistic effect of benzotriazole (BTA) and pyrazole (PZ). Electrochemical tests and UV–Vis spectra showed that they were effective inhibitors. The adsorption mechanism was investigated by fitting the adsorption isotherm and using quantum chemical calculations. Finally, the synergistic effect of BTA and PZ was studied by electrochemical experiments and corrosion characterization. The outcomes demonstrated that the surface quality and inhibition effect of composite inhibitor (BTA/PZ) were better than that of single inhibitor. This result could be the consequence of changes in the density and structure of the passive film composed of Cu and inhibitors. [ABSTRACT FROM AUTHOR]

Ancient bronze is subject to complex degradation which can lead, in cases where copper chlorides are present, to a cyclic and self-sustaining degradation process commonly referred to as "bronze disease". If left untreated, bronze disease can eat away at a bronze object until it is entirely deteriorated. The presence of copper trihydroxychlorides is indicative that this process is underway and therefore the detection of these corrosion products is necessary in guiding conservation of ancient bronze artefacts. In this paper we present a high spatial/spectral resolution short wave infrared (SWIR) imaging solution for mapping copper trihydroxychlorides in ancient bronze, combining hyperspectral imaging with an in-house developed unsupervised machine learning algorithm for automated spectral clustering. For this work, verification was obtained through use of an in-house developed reference database of typical ancient bronze corrosion products from several archaeological sites, and from collections of the National Museum of China. This paper also explores the suitability, and limitations, of a visible to near-infrared (VNIR) hyperspectral imaging system as a more accessible solution for mapping copper trihydroxychlorides associated with bronze disease. We suggest that our hyperspectral imaging solution can provide a non-invasive, rapid, and high resolution material mapping within and across bronze objects, particularly beneficial for analysing large collections in a museum setting. [ABSTRACT FROM AUTHOR]

Due to the excellent thermoelectric properties and low sintering temperature, nano-Ag paste is a promising die-attach material for high power electronic device. Unfortunately, it is difficult to resolve the critical issues including poor interfacial wettability, high porosity and poor high-temperature reliability of sintered nano-Ag joint. In this study, a novel bonding method was proposed to solve these problems by introducing Sn into the nano-Ag joint through the transient-liquid-phase (TLP) bonding technology. The Ag-Sn joint reported in this paper maintained excellent mechanical properties after high temperature aging and thermal shock test. The addition of Sn reduced the porosity of nano-Ag joint and improved the wettability of bonded interface. After aging at 200 °C for 2000 h, the shear strength still remains higher than 50 MPa. Besides, this bonding approach resolves the oxidization problem of Cu substrate at high temperature. The molecular dynamics (MD) simulation results indicate the addition of Sn could effectively inhibit the permeation of oxygen into the interface. [ABSTRACT FROM AUTHOR]

There is an urgent need for miniature heat sinks with superhydrophobic and efficient heat transfer properties for power-intensive electronic devices to operate properly under harsh conditions. Therefore, this paper firstly establishes the simulation model of surface wetting performance of miniature heat sink with square columnar array microstructure based on the phase field method and investigates the effect of dimensional parameters on the surface wetting performance of miniature heat sink. Then, miniature heat sinks with square columnar array microstructures of different dimensional parameters were prepared by wire electrical discharge machining (WEDM), and the 2D micromorphology, surface wetting performance, and heat transfer performance of the miniature heat sinks were characterized. The experimental results show that the simulation model has a high accuracy and the difference between the experimental results is less than 4.1%. The contact angle of the miniature heat sink with column width, column distance, and column height of 400 μm, 400 μm, and 1000 μm, respectively, is 151.4°. The heat source temperature with this miniature heat sink installed is 109.5 °C, which is 32.1 °C lower than the heat source temperature of 141.6 °C with the polished purple copper block installed without microstructure, a reduction of up to 22.7%. The miniature heat sink is prepared by WEDM in one-step, without any chemical modification treatment, to obtain super hydrophobic and efficient heat transfer performance. [ABSTRACT FROM AUTHOR]

This paper completes the welding of 4-mm-pure copper with bobbin tool-friction stir welding technology for the first time, and we discovered the evolution of microstructure by combining the temperature field evolution, microstructure, mechanical properties, electrical properties, and chemical corrosion resistance of welded joints. The findings demonstrate that the temperature field is dynamic, with the advancing side experiencing the highest peak temperature (422 °C). The size of recrystallized grain in the stir zone (SZ) is slightly larger than that of the base metal (BM), and the "banded structure" of alternating coarse-grain bands and fine grain bands is observed in this region. The microstructure of the heat-affected zone (HAZ) has larger grain size. Both the advancing and retreating sides of the thermomechanically affected zone (TMAZ) have a distinct microstructure, with the advancing side having a more pronounced elongated and curved microstructure. The welded joint has a specific microstructure gradient from the standpoint of the overall microstructure, which results in the fracture location at TMAZ with the biggest microstructure gradient in the tensile test, and the welded joint's efficiency is only 57.56% of the base metal. At the same time, the resistivity and the chemical corrosion resistance of the welded joint will decrease. During the welding process, the grains in the stir zone mainly undergo geometric dynamic recrystallization and the heat-affected zone mainly undergoes dynamic recovery. [ABSTRACT FROM AUTHOR]

This paper presents research into the creation of refill friction stir spot welding (RFSSW) single-lap joints of 6082-T6 aluminum alloy and roll-bonded AlCu bimetallic sheet. The latter sheet comprises aluminum EN AW-1050A and electrolytic copper M1E in Z6 temper condition (after rolling) and with a 1:1 ratio of the Cu:Al layers. The welding parameters involved a variable plunge depth and welding time. The mechanical properties of the joints were determined in tensile/shear tests. The highest average value of the load capacity of the joint was observed in joints made with a tool plunge depth dt = 2.6 mm and total welding time tw = 4 s. The load capacity for this variant was an average of 5986.75 N with standard deviation SD = 166.15 N. A plug-type fracture on the aluminum layer of the bimetallic sheet was observed in RFSSW joints produced with a plunge depth of 2.6 mm. Increasing the tool rotational speed and thus generating heat resulted in a plug-type fracture on the upper sheet (aluminum alloy). In the case of joints produced with a plunge depth of 2 mm equal to the thickness of the upper sheet, the type of fracture mode with both welding times was found to be nugget debonding. [ABSTRACT FROM AUTHOR]

The aim of this paper is the green synthesis of copper nanoparticles (Cu NPs) via Quinoa seed extract. X-ray diffraction (XRD) results confirmed the production of the pure crystalline face center cubic system of the Cu NPs with an average crystallite size of 8.41 nm. Infrared spectroscopy (FT-IR) analysis confirmed the capping and stabilization of the Cu NPs bioreduction process. UV visible spectroscopy (UV–Vis). surface plasmon resonance revealed the absorption peak at 324 nm with an energy bandgap of 3.47 eV. Electrical conductivity was conducted assuring the semiconductor nature of the biosynthesized Cu NPs. Morphological analysis was investigated confirming the nano-characteristic properties of the Cu NPs as polycrystalline cubic agglomerated shapes in scanning electron microscopy (SEM) analysis. Transmission electron microscopy (TEM) analysis also was used to assess the cubic shapes at a particle size of 15.1 ± 8.3 nm and a crystallinity index about equal to 2.0. Energy dispersive spectroscopy (EDX) was conducted to investigate the elemental composition of the Cu NPs. As a potential utility of the biosynthesized Cu NPs as nano adsorbents to the removal of the Cefixime (Xim) from the pharmaceutical wastewater; adsorption studies and process parameters were being investigated. The following strategic methodology for maximum Xim removal was conducted to be solution pH 4, Cu NPs dosage 30 mg, Xim concentration 100 mg/L, and absolute temperature 313 K. The maximum monolayer adsorption capacity was 122.9 mg/g according to the Langmuir isothermal model, and the kinetic mechanism was pseudo-second-order. Thermodynamic parameters also were derived as spontaneous chemisorption endothermic processes. Antibacterial activity of the Xim and Xim@Cu NPs was investigated confirming they are highly potent against each Gram-negative and Gram-positive bacterium. [ABSTRACT FROM AUTHOR]

In this paper, we study the nucleation and growth of a copper(I) oxide layer during hydrothermal treatment of copper foil in an alkaline solution. Experimental (X-ray diffraction and scanning electron microscopy) data, Gibbs free energy calculations, and analysis of the growth process in terms of the Cabrera–Mott approach lead us to conclude that the hydroxide anion and dissolved oxygen concentrations play a key role in determining the phase composition and morphology of the hydrothermal treatment product. [ABSTRACT FROM AUTHOR]

This paper discusses about a facile transition metal tungstate thin films preparation method and their remarkable photoelectrochemical properties. The films of AWO4 (A2+ = Fe, Co, Ni, Cu) were deposited onto conductive fluorine-doped tin oxide (FTO) glass substrate. The results of X-ray diffraction analysis indicated the presence of crystalline films. Field emission scanning electron microscopy images revealed nanostructured materials. X-ray photoelectron studies were employed to analyze elemental and chemical composition. Optical behavior indicated indirect transitions for all AWO4 films. Photoelectrochemical studies displayed that AWO4 films were successfully used as photoanodes in a photoelectrochemical cell under polychromatic irradiation. From electrochemical measurement, it was possible to estimate the flat band potential and so prevising suitable application of photoelectrodes. This work reports for the first time a comparative and comprehensive photoelectrochemical study with AWO4 films prepared in a simple way. The results indicate that the films can be used as photoanodes in water splitting reactions and other photoelectrocatalytic applications. [ABSTRACT FROM AUTHOR]

Formation of plasmonically active silver, copper and composite silver-copper nanostructures were studied in this paper. Metallic nanostructures were fabricated by thermal disintegration, so called dewetting, of the thin films in an argon atmosphere. The formation process of the nanostructures was in-situ observed by a novel method, based on resistance measurements. The influence of the material and thickness of the initial thin film on temperature of their disintegration was investigated. Electrical measurements were validated by scanning electron microscopy observations, while metallic the behavior of nanostructures was studied by XPS method. The formation of silver-copper nanocomposite structures was confirmed by UV–vis spectroscopy. Plasmon resonance with two characteristic peaks for nanocomposite structures was observed. [ABSTRACT FROM AUTHOR]