Metallic Copper Particles Research Articles

Shape characterization of copper metallic particles recovered from jig separation of e-wastes

Shape characterization of copper metallic particles recovered from jig separation of e-wastes

Investigation into the mechanism of ignition of magnesium alloy plates by high-temperature molten droplet

The ignition and spread of magnesium alloy fires are mainly attributed to the ignition of high-temperature molten metal droplets, but the underlying ignition mechanism remains unclear. This study addresses this knowledge gap by employing metallic aluminum and copper particles heated to temperatures over 1200 °C. Systematically, these heated particles were released at a fixed rate onto a magnesium alloy plate located inside a controlled heating furnace that maintained a constant temperature of 500 °C. Experimental results show that whether there are irregular pores and cracks in the resulting molten product can be used as a criterion for judging whether the magnesium alloy sample ignites. Furthermore, it is worth noting that molten copper droplets of the same size exhibit a higher heat-carrying capacity than their aluminum counterparts when both are heated to the same temperature. In addition, this study expanded the research scope through numerical simulation and analysis, using the PATO (Porous-Material Analysis Toolbox) solver to clarify the transient heat conduction process between the high-temperature droplet and the magnesium alloy plate. Simulations show that heat transfer upon droplet impact is primarily longitudinal, directed toward the base of the material. This results in a significantly higher temperature in the center of the affected magnesium alloy plate than at its periphery. In summary, this study helps to improve the understanding of the dangers of high-temperature molten droplets, and it is of great significance to investigate fire accidents caused by high-temperature molten droplets.

Highly conductive copper-coated polyamide yarn for wearable sensing and Joule heating applications

A highly conductive yarn was developed by electroless deposition of copper metal particles on the polyamide 6 yarn. The successful incorporation of Cu particles into the substrate was revealed by surface and elemental characterizations. The Cu/PA 6 yarn exhibited superior electrical conductivity (2.3 Ω/cm) with improved mechanical properties. The excellent electromechanical properties demonstrated by the Cu/PA 6 composite revealed its sensing capacity for a wide range of strains. Therefore, the composite yarn was affixed to the different regions of the human body and was capable of successfully monitoring various human motions, including finger bending, wrist bending, knee bending, drinking, and writing. In addition, rapid heat generation with high and uniform surface temperature (66.3 °C at 4.0 V in 45 s) validated the potential of the Cu/PA 6 yarn for wearable thermal heating devices. Moreover, rapid heating at a lower voltage, when attached to a wristband, revealed the capability of the composite yarn for localized heating or region-specific temperature regulation for personalized healthcare or comfort. This study informs a facile and effective strategy for developing robust yarn-shaped e-textiles for advanced wearable sensing and thermal heating.

Transformation of Cu2O into Metallic Copper within Matrix of Carboxylic Cation Exchangers: Synthesis and Thermogravimetric Studies of Novel Composite Materials.

In order to systematize and expand knowledge about copper-containing composite materials as hybrid ion exchangers, in this study, fine metallic copper particles were dispersed within the matrix of a carboxyl cation exchanger (CCE) with a macroporous and gel-type structure thanks to the reduction of Cu2O particles precipitated within the matrix earlier. It was possible to introduce as much as 22.0 wt% Cu0 into a gel-type polymeric carrier (G/H#Cu) when an ascorbic acid solution was used to act as a reducer of Cu2O and a reagent transforming the functional groups from Na+ into the H+ form. The extremely high shrinkage of the porous skeleton containing -COOH groups (in a wet and also dry state) and its limited affinity for water protected the copper from oxidation without the use of special conditions. When macroporous CCE was used as a host material, the composite material (M/H#Cu) contained 18.5 wt% Cu, and copper particles were identified inside the resin beads, but not on their surface where Cu2+ ions appeared during drying. Thermal analysis in an air atmosphere and under N2 showed that dispersing metallic copper within the resin matrix accelerated its decomposition in both media, whereby M/H#Cu decomposed faster than G/H#Cu. It was found that G/H#Cu contained 6.0% bounded water, less than M/H#Cu (7.5%), and that the solid residue after combustion of G/H#Cu and M/H#Cu was CuO (26.28% and 22.80%), while after pyrolysis the solid residue (39.35% and 26.23%) was a mixture of carbon (50%) and metallic copper (50%). The presented composite materials thanks to the antimicrobial, catalytic, reducing, deoxygenating and hydrophobic properties of metallic copper can be used for point-of-use and column water/wastewater treatment systems.

Copper-based nanoparticles supported on functionalized kaolinite for catalytic reduction of nitroaromatic compounds

A catalyst was synthesized by in situ reduction of Cu(II) ions on kaolinite particles. The clay mineral was modified by grafting propane sultone, to promote the stability of the catalyst and the good distribution of metal particles. Physicochemical characterizations revealed that the abundant synthesized metallic particles (mainly copper(I) oxide (Cu2O) although metallic copper particles were also present)) were of nanometric sizes. The catalyst was successfully applied for the catalytic reduction of three nitroaromatic compounds (4-nitrphenol, 4-chloronitroaniline, and 4-nitrocatechol). The variation of some experimental parameters was performed and marked effects on reaction rates were observed (increase with the catalyst concentration and decrease with the concentration of nitroaromatic compounds). An attempt to elucidate the mechanism of the catalytic reaction revealed that the adsorption of dihydrogen on the metal particles controlled the reaction rate while the adsorption of the nitroaromatic compounds controlled the induction time preceding the reduction reaction.

The effect of particle geometry (size & shape) on the recovery of gold and copper metallic particles from end-of-life random access memory cards by flotation

Since Random Access Memory (RAM), one of the main parts of computers contains a remarkable quantity of precious metals, applying flotation at the pre-concentration stage to recycle these metals can result in a more cost-effective, user-friendly, and environmentally friendly process compared to direct chemical methods. While the significance of physical characteristics like particle size and shape in the flotation process is well established, the impact of particle shape in the flotation process utilized in the recycling of end-of-life (EoL) RAMs hasn’t yet been thoroughly investigated. To fill this gap, a two-stage coarse flotation approach is used for the selective recovery of plastic and valuable metallic particles for sustainable development. The particle geometry of metallic particles recovered by flotation was characterized by axis measurement on the images by optical microscope that allows us to distinguish particles of different sizes and colors that make up the sample and evaluated in terms of particle size distribution (PSD), elongation (E) and roundness (R) parameters. The results showed that after the plastic fraction is effectively removed, it is possible to produce pre-concentrated products with high metal content (more than 50 % Cu content at the 1st stage and 1800 g/t Au content at the 2nd stage using 900 g/t KAX) in an economical and environmentally friendly way. Thus, it was concluded that the gold and copper metallic particles in the reduced-size EoL RAM cards could be easily floated by attaching them to the air bubble with the help of the collector, thanks to their flat shape.

Light, Copper, Action: Visible-Light Illumination Enhances Bactericidal Activity of Copper Particles.

Bacteria are an old concern to human health, as they are responsible for nosocomial infections, and the number of antibiotic-resistant microorganisms keeps growing. Copper is known for its intrinsic biocidal properties, and therefore, it is a promising material to combat infections when added to surfaces. However, its biocidal properties in the presence of light illumination have not been fully explored, especially regarding the use of microsized particles since nanoparticles have taken over all fields of research and subjugated microparticles despite them being abundant and less expensive. Thus, the present work studied the bactericidal properties of metallic copper particles, in microscale (CuMPs) and nanoscale (CuNPs), in the absence of light and under white LED light illumination. The minimum bactericidal concentration (MBC) of CuMPs against Staphylococcus aureus that achieved a 6-log reduction was 5.0 and 2.5 mg mL-1 for assays conducted in the absence of light and under light illumination, respectively. Similar behavior was observed against Escherichia coli. The bactericidal activity under illumination provided a percentage increase in log reduction values of 65.2% for S. aureus and 166.7% for E. coli when compared to the assays under dark. This assay reproduced the testing CuNPs, which showed superior bactericidal activity since the concentration of 2.5 mg mL-1 promoted a 6-log reduction of both bacteria even under dark. Its superior bactericidal activity, which overcame the effect of illumination, was expected once the nanoscale facilitated the interaction of copper within the surface of bacteria. The results from MBC were supported by fluorescence microscopy and atomic absorption spectroscopy. Therefore, CuMPs and CuNPs proved to have size- and dose-dependent biocidal activity. However, we have shown that CuMPs photoactivity is competitive compared to that of CuNPs, allowing their application as a self-cleaning material for disinfection processes assisted by conventional light sources without additives to contain the spread of pathogens.

Dimethyl Ether Carbonylation on H-MOR Zeolite, Modified Cu, Co, Mg

Mordenite and ferrierite (Zeolyst International, H-form, SiO2/Al2O3 ≈ 20) were used to study the adsorption, thermally programmed desorption, and carbonylation of dimethyl ether (DME). The behavior of mordenite with Cu, Co, and Mg cations introduced by ion exchange has also been studied. DME carbonylation was carried out at 200°C, pressure 3 MPa, space velocity 8000 ml g–1 h–1 in a mixture, vol. %: ⁓2.2 DME, 92.8–95.5 CO, rest. N2. After the induction period, the methyl acetate content is about 4–5 times higher for mordenite compared to ferrierite. The formation of water, methanol and hydrocarbons was observed in small quantities. The introduction of Cu, Co, Mg cations into mordenite by ion exchange (single ion exchange, cation/Al ratio no more than 35%) not only increased the stability, but also increased the activity in the DME carbonylation reaction. It was found that an increase in the content of copper (from 1.19 to 2.23 wt %) and Mg (from 0.62 to 1.8 wt %) differently affects the activity. In the case of copper, an increase in activity was observed, while in the case of magnesium, the activity decreased. Preliminary reduction of copper-exchange mordenite leads to a decrease in activity and the appearance of metallic copper particles on the surface of mordenite crystallites. According to in situ diffuse reflectance infrared spectroscopy, the introduction of magnesium cations by triple ion exchange leads to a noticeable decrease in the number of Brønsted acid sites (BACs) in both the 12-MR and 8-MR channels of mordenite. The catalytic characteristics of ferrierite practically do not change when copper and magnesium are introduced by ion exchange.

Reflections into Ptolemaic Glass II: Characterizing Yellow, Yellowish‐orange, Red, and Brown Inlays from Tebtynis

AbstractA systematic and extensive analytical study was carried out on the loose inlays discovered in the Ptolemaic workshop of Tebtynis (Fayum oasis, Egypt). This paper presents data derived from the multi‐methodological archaeometric investigations (optical microscopy, scanning electron microscopy–energy‐dispersive spectroscopy, electron probe microanalysis, micro‐Raman spectroscopy) performed on a set of intentionally colored and opacified glasses. In particular, we will discuss the textural, chemical, and mineralogical results related to the study of the yellow, yellowish‐orange, red, and brown inlays and semi‐finished/waste products now preserved at the Museo Egizio, Torino. The results highlight the presence of natron (low‐magnesium glasses, LMG) and plant ash (high‐magnesium glasses, HMG) base glass, coexisting with intermediate composition. Yellow samples are opacified using lead antimonates doped with iron and sometimes tin; conversely, yellowish‐orange specimens and the only brown sample are characterized by nanocrystals of cuprite. Red glasses are found in two variants: Dull reds are HMG with colloidal metallic copper particles, while sealing‐wax reds show LMG composition, associated with dendritic cuprite dispersed in a transparent, greenish matrix.

Antibacterial and Antifungal Properties of Polyester, Polylactide, and Cotton Nonwovens and Fabrics, by Means of Stable Aqueous Dispersions Containing Copper Silicate and Some Metal Oxides.

Literature reviews have described the applications of silver, copper, and zinc ions and metallic particles of Cu, Ti, and Zn oxides, which have been found to be useful antimicrobial reagents for the biofunctionalization of various materials and their surfaces. For this purpose, compositions of water dispersions containing emulsions of synthetic copolymers based on acrylic and vinyl monomers, polysaccharides (hydroxyethyl cellulose and starch), and various additives with wetting and stabilizing properties were used. Many stable water dispersions of different chemical compositions containing bioactive chemical compounds (copper silicate hydrate, titanium dioxide, and zinc oxide (and other auxiliary substances)) were developed. They were used for the preparation of thin hybrid coatings having good antimicrobial properties against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus), and yeast fungus (Candida albicans). Polyester (PES) and polylactide (PLA) nonwovens were modified using the dip-coating method, while PES and cotton fabrics were biofunctionalized by means of dip-coating and coating methods. The antimicrobial (antibacterial and antifungal) properties of the textile materials (nonwovens and fabrics) biofunctionalized with the above-mentioned bioactive agents exhibiting antimicrobial properties (CuSiO3, TiO2, ZnO, or ZnO∙SiO2) were strongly dependent on the agents' content in the water dispersions. The PES and PLA nonwovens, modified on the surface with water compositions containing copper silicate hydrate, showed good antibacterial properties against the Gram-negative bacteria Escherichia coli, even at a content of 1 wt.% CuSiO3∙xH2O, and against the Gram-positive bacteria Staphylococcus aureus, at the content of at least 5 wt.% CuSiO3∙xH2O. The bacterial growth reduction factor (R) was greater than 99% for most of the samples tested. Good antifungal properties against the fungus Candida albicans were found for the PES and PLA nonwoven fabrics modified with dispersions containing 5-7 wt.% CuSiO3∙xH2O and 4.2-5.0 wt.% TiO2. The addition of TiO2 led to a significant improvement in the antifungal properties of the PES and PLA nonwovens modified in this way. For the samples of PES WIFP-270 and FS F-5 nonwovens, modified with water dispersions containing 5.0 wt.% CuSiO3∙xH2O and 4.2-5.0 wt.% TiO2, the growth reduction factor for the fungus Candida albicans (R) reached values in the range of 80.9-98.0%. These new biofunctionalized polymeric nonwoven textile materials can find practical applications in the manufacture of filters for hospital air-conditioning systems and for the automotive industry, as well as in air purification devices. Moreover, similar antimicrobial modification of fabrics with the dip-coating or coating methods can be applied, for example, in the fabrication of fungi- and mold-resistant garden furniture.

Transformation of cuprite to tenorite through a martensitic-like type process in copper-doped glasses annealed in reduced atmosphere with the metal copper formation

The incorporation of copper nanoparticles into the glass matrix has attracted great interest in many fields due to their significant physical and chemical properties and their applications (e.g. opto-electronic and bio-medical tools). Several methodologies, such as the doping method and subsequent annealing of the glass in oxidizing and reducing atmospheres to synthesize copper nanoparticles in a glass are widely used. In this work, the doping method and subsequent annealing of the glass in a Ar/H2 atmosphere has been used. This treatment caused a martensitic-type transformation which, to our knowledge, has not been mentioned in the literature. The result was the transformation from cuprite to tenorite about 300°C, and the presence of dispersed rounded and polyhedral copper nanoparticles and dendritic shapes of nanoparticles. The reaction of CuO and H2, between 250 and 300°C, originated metallic copper particles. The mechanism of the martensitic-type transformation has been derived from the characterization results of copper-doped glasses annealed in reduced atmosphere by optical microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The martensitic-like type structure could have imparted shape memory characteristics to the copper-doped glasses annealed in reduced atmosphere, opening a window for future research.

Effect of epoxy resin addition on properties and corrosion behavior of sintered joints in power modules serviced offshore

Power modules applied in offshore applications are facing risks of corrosion failures on die-attach materials due to high humidity and H2S exposure. To investigate such corrosion behavior for sintered die-attach materials, we conducted a study with four groups of samples fabricated using copper and silver metal particles under different solvent systems. Such samples were firstly subjected to high-humidity-H2S conditions for 168 h to simulate the harsh offshore environment. After undergoing corrosion, the primary compounds formed were CuO/Cu2O and Ag2S through SEM, XRD, and XPS analysis. Notably, the incorporation of epoxy resin into sintered copper joints resulted in a remarkable reduction in corrosion and a substantial improvement in electrical conductivity after the reaction. In contrast, while the addition of epoxy did not evidently reduce corrosion in silver joints, it did lead to a significant increase in shear strength. Furthermore, to gain further insights into the effect of epoxy resin on corrosion behavior, electrochemical analysis, and molecular dynamics simulations were conducted. Finally, the mechanical reliability of the corroded copper and silver joints was evaluated through thermal shock tests. In summary, sintered copper joints exhibited better anti-corrosion behaviors than sintered silver under high humidity and H2S exposure, especially with the addition of epoxy resin. However, the corrosion products of sintered copper suffered from a sharp decrease in shear strength after thermal shock tests than sintered silver, which is probably due to the coefficient of thermal expansion mismatch.

Thermodynamic Calculations of Direct Reduction Smelting Technology of Copper Oxide Ores Based on Smelting Slag from the Yubeidi Site, Yunnan Province

The current research on metallurgical remains from scientific excavations in northeast Yunnan from the Bronze Age period is insufficient. In order to study the smelting technology of the Bronze Age in north-eastern Yunnan, samples of slag and mineral excavated from the Yubei Di site in Dongchuan were examined. Based on the outcome of the characterization analysis, a simulation was executed utilizing the software Factsage 7.1 in order to generate a phase diagram that accurately portrays the melting procedure. This simulation aimed to produce the most credible representation of the phase transition by employing computational methods. Characterisation methods included Metallographic Microscopy, Scanning Electron Microscopy Energy Dispersive Spectromicropy (SEM-EDS), X-ray diffraction (XRD), and Radiocarbon Date (14C dating). The results showed that there was much copper ore left in the slag of the site. Most of these copper ores were in the form of copper ferrite or cuprous oxide. The copper ore was copper oxide ore, and metal copper particles appeared in a small amount of the slag. Most of the slags unearthed from the site of the Yubeidi site were products of sulfur-containing oxide reduction and smelting into copper. Based on the outcomes of the simulations, it was established that the slag excavated from the Yubeidi site was mainly from the reduction and smelting process of sulphur-containing copper oxide minerals into copper, without consciously adding fluxes, not having mastered the slag-making techniques for different types of copper ores, and with primitive techniques. The carbon 14 dating results show that the age of the slag was during the Spring and Autumn Period and the Warring States Period.

Visualizing Structural and Chemical Transformations of an Industrial Cu/ZnO/Al2O3 Pre‐catalyst during Activation and CO2 Reduction

AbstractThe typical industrial catalyst used for methanol synthesis is a multi‐component catalyst based on Cu/ZnO/Al2O3. The synergies between various phases of this catalyst play a vital role in defining the overall catalytic function and performance. To gain insights into the role and interaction between the relevant components and phases, ex situ and in situ transmission electron microscopy (TEM) was deployed to investigate the structures and phases of an industrial Cu/ZnO/Al2O3 in its precursor, activated and reaction states. High structural inhomogeneity in this material is revealed, i. e. the presence of various phases with different morphologies and compositions. It is shown how structural and compositional changes occur during hydrogen treatment and how compositional inhomogeneity in the starting material translates into differences in the local composition of the activated and working catalyst. The formation of defective metallic copper particles (stacking faults and twins) that are in an intimate contact with zinc oxide (poorly crystalline, partially reduced ZnOx and crystalline ZnO), alumina, Zn−Al oxide and carbon‐zinc‐oxygen containing phases (such as zinc formate) is observed. It is also uncovered that alumina plays a potentially important role in stabilizing cationic zinc species. This work provides atomic‐level insight into the relevant state of an industrial methanol synthesis catalyst and the associated synergistic interplay between the involved phases in reactive atmosphere.

Effect of the addition of ductile phase on mechanical properties of Alumina/nano SiC ceramic composite

ABSTRACT Silicon carbide reinforcement in Alumina possess better physical and mechanical properties at elevated temperature. However, addition of second phase ceramic to matrix enhances the strength and hardness but it moderately improves the fracture toughness. The reason is due to lack of plastic deformation. Addition of ductile metallic phase helps in bridging the advancing crack in the matrix. In the present study, Alumina/nano SiC ceramic composite is toughened by the addition of copper metal particles. The influence of these metallic particles on behavior and mechanical properties of Alumina/SiC ceramic composite have been studied. The composite is processed using microwave hybrid sintering technique (2800 Watt) for one hour at 1400℃ and 1500℃. After sintering, microstructure of sample, grain size, relative densification, hardness and toughness have been examined. Highest densification of 93% and hardness of 1590 HV is achieved at 1400℃ sintering temperature while highest fracture toughness of 3.9 MPa m1/2 is achieved at temperature of 1500℃ with coarsening of alumina grains. The ductile phase in ceramic has proven to be effective for better bonding. It creates ceramic-metal bonds, which act as a tiny metal matrix between ceramic particles and contribute to ductile phase toughening in developed (Alumina/5% nano SiC/5%Cu) ceramic composite.

Low-Temperature Sintering of l-Alanine-Functionalized Metallic Copper Particles Affording Conductive Films with Excellent Oxidative Stability.

Here, the alpha amino acid l-alanine is employed as both a capping and stabilizing agent in the aqueous synthesis of submicron-sized metallic copper particles under ambient atmospheric conditions. The reduction of the copper(II) precursor is achieved using l-ascorbic acid (vitamin C) as the reducing agent. The nature of the complex formed between l-alanine and the copper(II) precursor, pH of the medium, temperature, and the relative proportion of capping agent are found to play a significant role in determining the size, shape, and oxidative stability of the resulting particles. The adsorbed l-alanine is shown to act as a barrier imparting excellent thermal stability to capped copper particles, delaying the onset of temperature-induced aerial oxidation. The stability of the particles is complemented by highly favorable sintering conditions, rendering the formation of conductive copper films at significantly lower temperatures (T ≤ 120 °C) compared to alternative preparation methods. The resulting copper films are well-passivated by residual surface l-alanine molecules, promoting long-term stability without hindering the surface chemistry of the copper film as evidenced by the catalytic activity. Contrary to the popular belief that ligands with long carbon chains are best for providing stability, these findings demonstrate that very small ligands can provide highly effective stability to copper without significantly deteriorating its functionality while facilitating low-temperature sintering, which is a key requirement for emerging flexible electronic applications.

Corrosion Mechanism of Microporous Nickel-Chromium Coatings: Part II. SECM Study Monitoring Cu2+ and Oxygen Reduction

The corrosion mechanism of microporous nickel-chromium multilayer coatings was studied at localised scale by Scanning Electrochemical Microscopy (SECM) after exposure to an aggressive electrolyte (chloride-based one at pH 3.1 containing cupric ions). The open circuit potential was initially monitored during 22 h, followed by a detailed characterisation using Glow Discharge-Optical Emission Spectroscopy and Field Emission Scanning Electron Microscope. Interestingly, Cu deposition occurs over the surface of the microporous nickel layer, and it is located on spots where micro-discontinuities (i.e., cracks and pores) of the outermost Cr layer are present. The application of different operation modes of the SECM (i.e., redox competition and surface generation/tip collection) not only reveals such copper deposits (which were identified after monitoring their catalytic capabilities for oxygen reduction reaction) but also confirms the stepwise reduction of Cu2+ to Cu0 (via intermediate species of Cu+) during the corrosion process. The impact of metallic copper particles in the local pH due to their catalytic activity could also explain why the microporous nickel layer is not corroded after exposure to such electrolyte.

Diffusion behaviors and mechanism of copper-containing sulfide in fayalite-type slag: A key step of achieving copper slag depletion

The dissolution behaviors of copper-containing sulfide (Cu2S) in fayalite-type slag have been deeply studied through experimental research and theoretical calculations. Results show that there are three phase changes in the process of Cu2S dissolution in the fayalite- matrix: (1) the formation of metallic copper particles and ferric iron by a redox reaction; (2) the formation of a matte (Cu2−xFexS) by crystallization; and (3) chemical dissolution to form copper-doped fayalite. The formed Fe(III)-O(BO)-Si increases the content of bridging oxygen in the slag, which slows the migration and growth of metal particles. The dissolved Cu(I) substitutes at the M1 (Fe-O-Fe) site in the fayalite lattice to form the Si-O-Fe(II)-O-Cu(I)-O-Fe(III) structure or substitutes at the M2 (Fe-O-Si) site to form the Si-O-Cu(I)-O-Fe(II)-O-Fe(III) structure to obtain a copper-doped fayalite complex, and the probability is equal for Cu(I) substituting at M1 and M2. Copper-doped fayalite is the main phase causing the chemical loss of copper in the smelting slag, and is difficult to recover by traditional flotation. Through the directional modification of the copper-doped fayalite, making Cu-O-Si bond to transform into Cu-O-S bond that is easy to be leached or Cu-S bond that is easy to be reselected, which can realize the efficient recovery of copper resources from slag. These findings provide theoretical support for improving copper resource recovery in slag or reducing copper loss when producing slag during copper smelting.

Prospects for the creation of antimicrobial preparations based on copper and copper oxides nanoparticles

The spread of strains of microorganisms that are multidrug resistant to modern antimicrobial drugs is still an urgent problem in the treatment and prevention of infectious diseases and public health in general.Currently, the possibility of using metal nanopreparations in various fields of medicine is being actively studied. Nanoparticles of metals and metal oxides are promising antimicrobial agents and are attracting growing interest due to their effectiveness. Nanoscale copper metal particles have shown high antimicrobial activity againstvarious types of gram-positive and gram-negative bacteria, as well as fungi. Taking into account the potential of copper nanoparticles in antimicrobial therapy, we present an overview of the current state of research related to their antimicrobial properties, consideration of the mechanisms of action, key factors affecting antimicrobial activity, including the polymer matrix. The issues of toxicity and resistance to copper are considered. The advantage of copper nanoparticles over other metal nanoparticles is shown.The studies summarized in this review have shown the promise of copper nanoparticles in the creation of new antimicrobial drugs that can be used in the future to control, prevent, and treat various diseases.

Boron Modified Bifunctional Cu/SiO2 Catalysts with Enhanced Metal Dispersion and Surface Acid Sites for Selective Hydrogenation of Dimethyl Oxalate to Ethylene Glycol and Ethanol.

Boron (B) promoter modified Cu/SiO2 bifunctional catalysts were synthesized by sol-gel method and used to produce ethylene glycol (EG) and ethanol (EtOH) through efficient hydrogenation of dimethyl oxalate (DMO). Experimental results showed that boron promoter could significantly improve the catalytic performance by improving the structural characteristics of the Cu/SiO2 catalysts. The optimized 2B-Cu/SiO2 catalyst exhibited excellent low temperature catalytic activity and long-term stability, maintaining the average EG selectivity (Sel.EG) of 95% at 190 °C, and maintaining the average EtOH selectivity (Sel.EtOH) of 88% at 260 °C, with no decrease even after reaction of 150 h, respectively. Characterization results revealed that doping with boron promoter could significantly increase the copper dispersion, enhance the metal-support interaction, maintain suitable Cu+/(Cu+ + Cu0) ratio, and diminish metallic copper particles during the hydrogenation of DMO. Thus, this work introduced a bifunctional boron promoter, which could not only improve the copper dispersion, reduce the formation of bulk copper oxide, but also properly enhance the acidity of the sample surface, so that the Cu/SiO2 sample could exhibit superior EG selectivity at low temperature, as well as improving the EtOH selectivity at high temperature.