Small Amount Of Cu Research Articles

Microstructures, mechanical properties and damping performance of wrought Mg–Cu–Ca alloys

Mg–Cu–Ca alloy sheets show good room temperature formability and excellent thermal conductivity; however, their strength is insufficient for load-bearing applications. In this study, Mg–Cu–Ca ternary alloys were subjected to a conventional extrusion process, and the microstructures and tensile properties were systematically evaluated. The addition of extremely small amounts of Cu and Ca to pure Mg (Mg–0.03Cu–0.05Ca, wt%) led to significant refinement of dynamically recrystallized (DRXed) grains while preserving a certain fraction of un-DRXed grains, which contributed to a substantial increase in tensile yield strength. Adjusting the extrusion parameters further increased the tensile yield strength to 329MPa, driven by the combined effects of further refined DRXed grains and an increased area fraction of un-DRXed grains. The damping performance of the Mg–0.03Cu–0.05Ca alloy sheet was superior to that of commercial AZ31(Mg–3Al–1Zn–0.3Mn in wt%) alloy sheet but lower than that of pure Mg, particularly at low frequencies. This revealed that the solute segregation at grain boundaries plays a crucial role in the damping performance of Mg alloys.

Surface Facets Reconstruction in Copper-Based Materials for Enhanced Electrochemical CO2 Reduction.

The unavoidable and unpredictable surface reconstruction of metallic copper (Cu) during the electrocatalytic carbon dioxide (CO2) reduction process is a double-edged sword affecting the production of high-value-added hydrocarbon products. It is crucial to control the surface facet reconstruction and regulate the targeted facets/facet interfaces, and further understand the mechanism between activity/selectivity and the reconstructed structure of Cu for CO2 reduction. Based on the current catalyst design methods, a facile strategy combining chemical reduction and electro-reduction is proposed to achieve specified Cu(111) facets and the Cu(110)/(111) interfaces in reconstructed Cu derived from cuprous oxide (Cu2O). The surface facet reconstruction significantly boosted the electrocatalytic conversion of CO2 into multi-carbon (C2+) products comparing to the unmodified catalyst. Theoretical and experimental analyses show that the Cu(110)/(111)s interface between Cu(110) and a small amount of Cu(111) can tailor the reaction routes and lower the reaction energy barrier of C-C coupling to ethylene (C2H4). The work will guide the surface facets reconstruction strategy for Cu-based CO2 electrocatalysts, providing a promising paradigm to understand the structural variation in catalysts.

Unique CuOx–FeOx interfaces in Cu-decorated Fe-based catalysts facilitating CO2 hydrogenation to higher hydrocarbons

Currently, research on iron-based catalysts applied in CO2 hydrogenation to higher hydrocarbon products (C2+), especially light olefins, has gained significant attention. However, a comprehensive understanding of the synergy between active Fe-containing species and promoters on their catalytic performances is still lacking. In this study, ZrO2-supported Cu-decorated iron catalysts were constructed through the coprecipitation with the aid of a microliquid-film reactor and evaluated in CO2 hydrogenation. It was shown that the incorporation of a small amount of Cu promoted the reduction of Fe species and facilitated the formation of surface defective Fe3O4 (FeOx) component containing a large number of oxygen vacancies and thus highly dispersed surface CuOx/FeOx structures. Notably, the 2.0 wt% Cu-incorporated Fe-based catalyst exhibited superior performance, along with high selectivity to C2+ products (77.1 %) and yield of C2+ products (27.3 %) under reaction conditions (i.e., 4800 mL·gcat-1·h−1, 2.0 MPa, and 320 ℃), outperforming the current state-of-the-art Fe-based catalysts. Through a combination of comprehensive structural characterizations and density functional theory calculations with reaction results, it was unveiled that surface FeOx favored CO2 adsorption and H2 dissociation, and meanwhile, CuOx component with high Cu+ fractions adjacent to FeOx on Cu-decorated Fe-based catalysts also could remarkably promote H2 dissociation and the adsorption of CO2 and CO intermediate. Therefore, such-generated unique CuOx–FeOx interfaces in Fe-based catalysts could facilitate the generation of adsorbed adjacent CHx species through both the hydrogen-assisted indirect dissociation pathway of CO intermediate and the formate intermediate pathway, thus promoting CO2 hydrogenation to higher hydrocarbons. This work affords a promising strategy for the construction of Fe-based based catalysts to boost CO2 hydrogenation to higher hydrocarbon products and a deep understanding of the role of CuOx–FeOx interfaces in CO2 hydrogenation.

Flexible Copper Films Modification via Spontaneous Reduction of Aryldiazonium Gold Salts: Unraveling Surface Properties and Energy Profile.

In this study, we report the modification of flexible copper films via the spontaneous reduction of aryldiazonium gold salts [X-4-C6H4N≡N]AuCl4 (X═COOH, NO2). The electroless modification involves dipping of flexible copper films in the aryldiazonium gold solutions for a few seconds, under ambient conditions, followed by a washing step with deionized water to obtain a mechanically robust gold-aryl coating. The chemical composition, morphology, electronic structure, and optical properties of the gold-aryl layer and the flexibility of the modified copper films are supported by the results from X-ray photoelectron spectroscopy (XPS), electrochemistry, contact angle, scanning electron microscopy (SEM), and ultraviolet photoelectron spectroscopy (UPS). XPS surface analysis showed metallic gold in addition to C-C, C-O/C-N, and C═O functional groups from the grafted aryls. Cu 2p showed metallic copper as a major component and a small amount of Cu(II) ions. Wettability studies showed that Au-COOH@Cu increased the contact angle of the bare copper films from 68.0 ± 0.7° to 82.0° ± 0.7°, while Au-NO2@Cu increased the contact angle to 134.0° ± 0.3°. UPS energy profile analysis of [HOOC-4-C6H4N≡N]AuCl4 (valence band maximum = 1.91 eV) exhibited greater reducibility than [O2N-4-C6H4N≡N]AuCl4 (valence band maximum = 2.91 eV). The lower ionization potential of [HOOC-4-C6H4N≡N]AuCl4 (IP = 4.33 eV) enhanced the reactivity upon copper film contact, potentially inducing efficient energy level alignment, compared with [O2N-4-C6H4N≡N]AuCl4 (IP = 5.62 eV). UPS results were further supported by electrochemistry investigation which revealed that [HOOC-4-C6H4N≡N]AuCl4 is easily reducible compared with [O2N-4-C6H4N≡N]AuCl4. The findings presented here hold significant implications for developing flexible copper films and pave the way for future advancements in electronic material modification for industrial applications.

Impact of grazing around industrial areas on milk heavy metals contamination and reproductive ovarian hormones of she-camel with assessment of some technological processes on reduction of toxic residue concentrations

Heavy metals are one of the most toxic chemical pollutants of the environment. Their hazards not restricted to human but extend to animal productivity and reproductively. The present study aimed to assess the impact of grazing around industrial areas on the levels of copper (Cu) and aluminum (Al) residues in milk samples collected from dromedary she-camels and studying their effects on some ovarian hormones. In addition, the study aimed to investigate methods of removal of the toxic concentrations of these heavy metals in milk by applying different technological processes. Blood and milk samples were collected from 30 dromedary she-camels, 15 grazing in non-industrial areas (group A) and 15 grazing in industrial areas (group B). Detection of the levels of these heavy metals in milk was done. Ovarian hormones investigation on the blood was performed. Different technological processes such as boiling, skimming and fermentation were applied to all contaminated samples to reduce the toxic concentrations of these heavy metals. Results revealed that all examined milk samples in both groups contained Cu, while 40% of group A and 100 % of group B contained Al residues with different concentrations. The levels of Cu and Al residues in samples of group A not exceeded the maximum residual limit (MRL) set by World Health Organization (WHO) while 60% and 100% of milk samples in group B contained Cu and Al residues exceeded MRL, respectively. Technological processes induce variant changes in the levels of these metals in milk. Heat treatment of milk in Al vats leads to leaching of Al from containers to the milk causing significant increase in Al load, while Cu level was not significantly affected. Boiling in stainless-steel containers decreased the levels of Al and Cu but in non-significant levels. Regarding skimming process, small amount of Cu and Al escaped into the skimmed milk while greater amount were recovered in the cream. Fermentation by probiotic bacteria showed that milk fermentation has non-significant effect on Cu and Al levels. Investigation of ovarian hormones (estrogen and progesterone) revealed presence of a signification reduction in the levels of these hormones in group B compared to group A. In addition, a negative correlation was found between these heavy metals and ovarian hormones concentrations in the blood. It is concluded that grazing of dromedary camels around industrial areas induce heavy metals toxicity represented by excretion of these metals in milk and significant reduction on ovarian function showed by reduction of estrogen and progesterone levels. Technological processes such as skimming decreased the levels of Al and Cu residues in milk.

TiO2/Ag-based photodeposited catalyst boosted electrochemiluminescence of ninhydrin-hydrogen peroxide system for ultrasensitive sensing of copper (II)

Photodeposited TiO2/Ag nanocomposites were generally used to be a friendly catalyst for degrading organic contaminant in environmental field. However, electrochemiluminescence (ECL) sensing analysis based on photocatalysts remains a significant challenge. Herein, polyvinylimide (PEI)-TiO2/Ag nanocomposites (PEI-TiO2/AgNCPs) film with reduced graphene oxide(r-GO) was constructed as a sensing interface for copper(II) ECL detection. TiO2/Ag nanocomposites was prepared by reversed phase microemulsion method and photodeposition technique. Moreover, it was discovered that a small amount of Cu2+ could obviously boost the ECL signal of ninhydrin-hydrogen peroxide system. Signal amplification was achieved by using the synergistic effect between r-GO and TiO2/Ag nanocomposites, and the efficiently concentrated effect of PEI to Cu2+. Furthermore, the investigation showed that ECL mechanism of ninhydrin-hydrogen peroxide system was attributed to the generated hydroxyl radical and superoxide anion during the several type of reactions. Thus for the first time, an ultrasensitive ECL approach for detecting Cu2+ could be performed using ninhydrin as an ECL signal probe and hydrogen peroxide as a co-reaction reagent. Under the suitable circumstances, the proposed method showed an excellent linear relationship in the concentration range of Cu2+ from 1.0 fM to 5.0 nM. Detection limit was estimated to be as low as 0.26 fM. The sensing interface expanded the application of photodeposited TiO2/Ag nanocomposites in ultrasensitive ECL detection. It has potential applications in other components and biological analysis.

Cu-Al spinel oxide as a sustained release catalyst for methanol steam reforming: Enhancing the catalytic performance via surface reconstruction

Cu-Al spinel oxide as a sustained release catalyst gradually releases active metal Cu during the methanol steam reforming reaction, whose catalytic behavior depends strongly on the surface structure of the catalyst. In this context, Cu-Al spinel solid solution is synthesized by a solid phase ball milling method, followed by treating with acidic and basic solutions in order to modulate the surface composition and structure, thereby to further improve the catalytic performance. Nitric acid is effective for the removal of both surface dispersed Cu and Al oxide species, whereas sodium hydroxide is only effective for the removal of Al oxide species, and ammonium hydroxide shows the weakest effect, removing a very small amount of Cu and Al species. Accompanying with the loss of Cu and Al species, the catalyst surface undergoes structural reconstruction, showing a redistribution of Cu species. Consequently, the copper releasing behavior varies drastically. The catalytic testing results show that the nitric acid and ammonium hydroxide treated catalysts present improved activity, where in the former also shows better stability. Sodium hydroxide treatment has a negative effect on the sustained releasing catalytic performance. In combination with the characterization results of the tested catalysts, it is found that both the copper particle dimension and the microstructure strain of sustained released copper play important roles in the catalytic performance. The findings of this report provide a practical method for the improvement of the sustained releasing catalysis.

Enhancing Microstructural and Mechanical Properties of Ferrous Medium-Entropy Alloy through Cu Addition and Post-Weld Heat Treatment in Gas Tungsten Arc Welding.

This study investigates the impact of a high-entropy alloy filler metal coated with copper (Cu) and post-weld heat treatment (PWHT) on the weldability of a ferrous medium-entropy alloy (MEA) in gas tungsten arc welding. The addition of 1-at% Cu had an insignificant effect on the microstructural behaviour, despite a positive mixing enthalpy with other elements. It was observed that a small amount of Cu was insufficient to induce phase separation into the Cu-rich phase and refine the microstructure of the as-welded specimen. However, with an increase in the PWHT temperature, the tensile strength remained mostly consistent, while the elongation significantly increased (elongation of as welded, PWHT700, PWHT800, and PWHT 900 were 19, 43, 55 and 68%, respectively). Notably, the PWHT temperature of 900 °C yielded the most desirable results by shifting the fracture location from the coarse-grained heat-affected zone (CGHAZ) to base metal (BM). This was due to significant recrystallisation and homogenised hardness of the cold-rolled BM during PWHT. However, the CGHAZ with coarse grains induced by the welding heat input remained invariant during the PWHT. This study proposes a viable PHWT temperature (900 °C) for enhancing the weldability of cold-rolled ferrous MEA without additional process.

Phytoremediation of Heavy Metal on Entisols and Plant Uptake Amended with Palm Oil Mill Effluent (POME) Sludge

Palm oil mill effluent (POME) sludge was derived from about 50% of wastewater effluent of fresh fruit bunch (FFB) productions. The objective of this study is to determine the effect of contaminant status which was applied with POME sludge on Entisols and plant uptake of maize growth. POME sludge obtained from the Jengka 8 FELDA Palm Oil was used in this study. The maize (Zea mays) was used as a test crop and planted in Rasau series soil (Entisols). The soil, leaves and stem samples were air-dried, homogenized and sieved. Heavy metal analysis identified the existence of Cu, Cr, Cd, Zn, Pb, Ni and Mn elements by the sequential extraction procedure using optical emission spectrometry (ICP-OES). The physicochemical of POME sludge showed that most heavy metals in each treatment fulfilled the WHO/FAO standard and were safe for human consumption. After applying treatments on Entisols, a small amount of Cu, Cr, Zn, Pb, Ni and Mn was retrieved from the exchanges phase. Small amount of Cr, Ni and Mn were identified in the stems and leaves. Zn, Cd, Pb and Cr were not detected in the bioavailable forms, while Cu was only available in the mixing ponds sludge samples. The results showed that most heavy metal properties contained low residual fractions from the soil and plant uptake in stems and leaves. The application of POME sludge in agricultural practices might offer a sustainable utilization of waste materials in the oil palm plantation.

Three-dimension porous Zn-Cu alloy: An inexpensive electrocatalyst for highly selective CO2 reduction to CO in non-aqueous electrolyte

Designing cheap and highly active electrochemical CO2 reduction (ECO2R) systems are crucial for their commercial applications. Herein, we report a 3D porous Zn-Cu alloy electrode for ECO2R to CO. A small amount of Cu has a dramatic effect on the micro-morphology of the electrode. Furthermore, DFT calculations confirm that Zn-Cu alloying significantly reduces the formation energy barrier of *CO intermediates. The synergy between the unique 3D porous structure and the alloying effect enables the Cu0.3Zn9.7 electrode to achieve up to 90.69 % Faraday efficiency (FE) for CO at −1.2 V (vs. reversible hydrogen electrode (RHE)). Furthermore, we prepare a novel non-aqueous cathode electrolyte consisting of deep eutectic solvent (DES) and propylene carbonate (PC) for ECO2R. The FECO of Cu0.3Zn9.7 increased to 94.89 % and the reduction potential decreased to −1 V (vs. RHE). The low cost of preparing 3D porous electrodes and the ease of synthesizing the novel non-aqueous electrolyte render this ECO2R system for CO promising for large-scale application.

Synergizing electrical, mechanical, and radiation shielding properties of dendritic copper filled epoxy polymer composites

The study examined the properties of epoxy composites with dendritic copper (Cu) particles through various tests, including FTIR, DSC, TGA, electrical conductivity, and mechanical tests. The addition of Cu particles to the composites improved their electrical conductivity and mechanical properties, particularly tensile strength and flexural modulus. The Tg temperature of the composites could be adjusted by varying the Cu particle ratio. Notably, in the study, we prepared composites with varying Cu particle concentrations, specifically at ratios of 1%, 2%, 3%, 4%, 5%, and 6%, and observed distinct effects on the properties of the epoxy-Cu composites. Although there was no chemical bonding between the epoxy and Cu particles, the Cu additive acted as a pinning agent, restricting the movement of the polymer chains. This suggests that incorporating small amounts of Cu into epoxy composites can enhance their properties, making them suitable for applications in the electrical and electronics industry. Additionally, we evaluated the shielding properties of selected epoxy-based composites incorporating copper powder against gamma radiation with energies of 59.5 keV, 661.6 keV, and 1332.5 keV, and also investigated the composites' ability to attenuate gamma rays, recommending specific composites (ECU6, ECU1, and ECU2) for different energy levels of gamma rays. SEM examinations showed that the addition of Cu particles significantly altered the microstructure and mechanical properties of the composites, resulting in an irregular and rough fracture surface and decreased structural integrity.

Increasing ductility via Cu addition in AlxCrFeMnNi: Towards a scrap-based high entropy alloy

Alloys comprising common alloying elements are more amenable to accepting high fractions of scrap. The present study examines the effect of Cu and Al addition on common element containing multiple principal element alloy (CE-MPEA): AlxCuyCrFeMnNi (x = 0, 0.15, 0.3, 0.6, 0.9 and y = 0, 0.07, 0 = 0.14). Alloys were fabricated by arc casting. As expected, after quenching, the microstructures displayed FCC A1, Cr-rich BCC A2 and B2 precipitate phases in varying amounts. Adding small amounts of Cu to low and medium Al alloy groups increased the FCC phase fraction and refined the FCC grains. It is proposed that these microstructural changes account for the increased ductility seen to accompany Cu addition. A hybrid model was successfully employed to predict the hardness of the FCC phase. In contrast to high Cu-containing HEAs from prior studies, Cu additions in the studied alloys did not detrimentally affect the corrosion resistance in idealised polarization corrosion tests in salt solution. This can be ascribed to the absence of a Cu-rich FCC phase at the low Cu levels employed in the present work. The current alloys show promise as a base composition for further development into a tough fine-grained stainless alloy able to be produced using high fractions of scrap input.

Electronic structures and photovoltaic properties of copper- or tin-doped cesium-based perovskite crystals

Electronic and crystal structures of CsPbIBr2 perovskite compounds doped with copper (Cu) or tin (Sn) were investigated. From the band calculations, an energy gap of CsPbIBr2 was reduced by the Cu or Sn doping, and optimized crystal structures of CsCuIBr2 were compared with the fabricated crystals. Energy gaps of Cu- or Sn-doped CsPbIBr2 were measured by optical absorption and external quantum efficiencies of the cells, and compared with the calculations. Addition of a small amount of Cu or Sn to the CsPbIBr2 increased the short-circuit current density of the fabricated solar cells, which agree with the expected results from the calculated band structures and partial density of states.

A green and sustainable approach for the preparation of Cu-containing alginate fibers

The development of biopolymer fibers is attracting considerable interest due to the need to reduce the environmental impact of the petroleum-based industry. With the aim to foster the use of biopolymer-based antimicrobial fibers, a green and sustainable preparation route for alginate fibers containing copper-based nanostructures is reported. Its strong antimicrobial properties and affinity for alginate make copper the ideal candidate for the preparation of products suitable for various applications. In this work alginate is extruded and crosslinked in a Cu2+ aqueous bath, producing a filiform hydrogel structure. Ascorbic acid was then used to reduce the metal ions and to form the aforementioned nanostructures. This in situ strategy for the reduction of coordinating Cu2+ ions is unprecedented and leads to a homogeneous distribution of the inorganic structures in the polymeric network. The entire process can be monitored through infrared spectroscopy and the performances (e.g., thermal stability, morphology, swelling, water retention, mechanical properties) of the obtained products are tunable as a function of the duration of each preparation step. The great affinity for water and the small amount of Cu2+ released as a function of time suggest promising perspectives for the use of these fibers in antimicrobial applications.

Atom probe tomography study of Cu precipitation behavior in 22Cr-13Ni-5Mn austenitic stainless steel

Cu precipitation behavior of a Cr-Ni-Mn austenitic stainless steel containing a small amount of Cu during aging between 923 and 1023 K for up to 24 h was investigated by atom probe tomography with cluster-finding and interfacial segregation analyses. At 923 K, Cu precipitation started at 20 min of aging, forming uniformly dispersed nano-sized precipitates and the number density of precipitates reached the maximum at 2 h of aging, although the volume fraction of precipitates continued to increase with increasing aging time up to 24 h. The precipitate size steadily increased with increasing aging time and temperature. The growth rate of Cu precipitates observed in this study is significantly lower than that in previous studies of other austenitic stainless steels, although the isothermal growth behavior obeys Lifshitz-Slyozov-Wagner theory. It was noted that both Ni and Mn were enriched near precipitate/matrix interfaces, reducing the interfacial energy as a result. This interfacial segregation seems to effectively reduce the growth rate of Cu precipitates during aging, which was significantly lower than that reported for other austenitic steels.

A Simple Process for the Recovery of Rare Earth Elements and Iron from Sulfuric Acid Leaching Solution of NdFeB Magnets by Double Salt Precipitation

ABSTRACT Recovery of rare earth elements (REEs) from spent NdFeB magnets is important to meet the increasing demand for magnets and high-tech applications. In general, pretreatments of spent NdFeB magnets are necessary to recover REEs such as Nd, Pr, and Ce from the magnets. In this work, a simple process was proposed to recover REEs without any pretreatment of NdFeB magnets by using precipitation of REE(III) double salt. The correlations among several variables on the precipitation of REE(III) double salt were investigated by using synthetic solutions such as the molar ratio of Na(I) and sulfuric acid to Nd(III), the concentration of Nd(III) and Fe(III). The REES and iron present in NdFeB magnets were completely dissolved in 2 M H2SO4 solution at room temperature. The dissolved REE(III) ions were then directly separated by precipitation of double salt when Na2SO4 was added at 80°C. After REEs precipitation, the addition of iron powder to the filtrate at room temperature reduced Fe(III) to Fe(II) and removed a small amount of Cu(II) and Co(II) by cementation. Then Fe(II) and Na2SO4 were separated by precipitation of Fe(OH)2 when solution pH was adjusted to 8. The conditions for the precipitation of Nd(III) double salt were thermodynamically verified. Mass balance of continuous experiments indicated that it was possible to recover REEs and iron with high purity by the proposed process in this work.

Mechanically robust antifouling coating with dual-functional antifouling strategy by infiltrating PDMS into plasma-sprayed porous Al2O3-Cu coating

Marine biofouling is a worldwide challenge that needs to be solved urgently. Poly(dimethylsiloxane) (PDMS)-based fouling release coatings with low surface free energy (SFE) could effectively inhibit biofouling. Nevertheless, their poor mechanical durability, adhesive strength, and antifouling performance under static conditions significantly limit their applications. Herein, a novel mechanically robust Al2O3-PDMS-Cu composite coating with strong adhesive strength and remarkable antifouling performance was developed. The Al2O3-PDMS-Cu coating loaded with a small amount of Cu was fabricated by infiltrating PDMS into plasma-sprayed micro/nano-scaled porous Al2O3-Cu coating. Results showed that the fabrication of this Al2O3-PDMS-Cu coating did not alter the surface hydrophobicity and SFE of PDMS significantly, thus presenting little influence on its inherent fouling release property. After rigorous abrasion test, the Al2O3-PDMS-Cu coating presented remarkably improved surface hydrophobicity due to the exposure of micro/nano structure, rather than falling off as that of PDMS coating. The combination of excellent abrasion resistance and one order of magnitude higher adhesive strength and hardness than PDMS coating contributed to the outstanding mechanical robustness of Al2O3-PDMS-Cu coating. Additionally, the antifouling assays against marine bacteria adhesion (95% reduction rate for Escherichia coli. (E. coli)) and algae attachment (96% and 94% reduction rates for Chlorella and Phaeodactylum tricornutum (P. tricornutum), respectively after 21 days of incubation) demonstrated the superior antifouling performance of the Al2O3-PDMS-Cu coating. Thus, a high-performance Al2O3-PDMS-Cu antifouling coating with excellent mechanical robustness and long-term antifouling performance was achieved via the combination of mechanical durability of Al2O3 skeleton and the dual-functional antifouling strategy, i.e., the fouling release property of PDMS and fouling resistance of Cu.

Analysis of Electric Transmission Failure Induced by Electrostatic Migration and Deposition of Abrasive Dusts in SADA

The electric transmission failure induced by the electrostatic migration and deposition of the friction-pair-produced abrasive dusts in the Solar Array Drive Assembly (SADA) is studied for the first time by integrating experiments and Finite Element Method (FEM) simulation. Particle morphology and composition are characterized by SEM and X-ray EDS, respectively. The size, distribution and average charge of the abrasive dusts are characterized by PSDA as well as the home-made particle charge measurement device. The results show that the dusts’ sizes are in the range of 10–40 μm, and the dusts are primarily composed of Ag and a small amount of Cu and S. Sliced abrasive dusts with an average diameter of 30 μm and a charge of 85 e are used for the FEM prediction of particle trajectory, which is consistent with the theoretical calculation results. The electromagnetic field distribution in the SADA and the electrostatic migration and deposition of abrasive dusts are predicted and analyzed by adopting the FEM method. The experimentally observed dusts’ trajectories in a vacuum chamber with 0.02 Pa vacuum degree are consistent with the simulation results, which qualitatively verifies the accuracy of the FEM model. The predicted results show that the irradiation-induced conductivity increase in polyimide material has little influence on the electric field distribution and the migration and deposition of the abrasive dusts but has great influence on the local current density. Both the potential differences between the two adjacent conducting rings and the loose contact between the electric brush and the conducting rings have significant influence on the migration and deposition of the abrasive dusts, which may greatly increase the surface discharge risk and the electrical transmission instability in the SADA. This study is conducive to the safe and stable operation of the on-orbit spacecrafts.

Co-delivery of a tumor microenvironment-responsive disulfiram prodrug and CuO2 nanoparticles for efficient cancer treatment.

Disulfiram (DSF) has been used as a hangover drug for more than seven decades and was found to have potential in cancer treatment, especially mediated by copper. However, the uncoordinated delivery of disulfiram with copper and the instability of disulfiram limit its further applications. Herein, we synthesize a DSF prodrug using a simple strategy that could be activated in a specific tumor microenvironment. Poly amino acids are used as a platform to bind the DSF prodrug through the B-N interaction and encapsulate CuO2 nanoparticles (NPs), obtaining a functional nanoplatform Cu@P-B. In the acidic tumor microenvironment, the loaded CuO2 NPs will produce Cu2+ and cause oxidative stress in cells. At the same time, the increased reactive oxygen species (ROS) will accelerate the release and activation of the DSF prodrug and further chelate the released Cu2+ to produce the noxious copper diethyldithiocarbamate complex, which causes cell apoptosis effectively. Cytotoxicity tests show that the DSF prodrug could effectively kill cancer cells with only a small amount of Cu2+ (0.18 μg mL-1), inhibiting the migration and invasion of tumor cells. In vitro and in vivo experiments have demonstrated that this functional nanoplatform could kill tumor cells effectively with limited toxic side effects, showing a new perspective in DSF prodrug design and cancer treatment.

Structural diagrams and thermodynamics relating to temperature and compositions of Ag561−nCun (n = 0-561) nanoalloys during cooling from atomic simulations

The packing changes of Ag_561-nCu_n (n = 0-561) nanoparticles during cooling were studied by molecular dynamics simulations at atomic scale. Structural diagrams as well as packing images presented liquid, disordered, and some ordered patterns. Pair distribution functions were used to characterize some typical structures. Potential energy and shape factors identified the transition’s temperature regime and the effect of cooling on the shape’s changes of the alloyed particles. The simulation results show composition effect on the transition temperatures and complex structural patterns. For these Cu-Ag nanoalloys, which contain small amount of Cu or Ag atoms, they show alternating FCC and icosahedral packing patterns at low temperatures, and core-shell configurations prefer to occur in the Cu-rich particles, where the Cu occupy the interior of the particles. Compositions and degree of orderliness in packing contribute to the entropy of the alloyed nanoparticles.