Reaction-Driven Migration Dynamics of Nano-Metal Particles Unraveled by Quantitative Electron Microscopies.

The stability of supported nano-metal catalysts holds significant importance in both scientific and economic practice, beyond the long pursuit of enhanced activity. While previous efforts have concentrated on augmenting the interaction between nano-metals and carriers, in the thermodynamic macro-perspective, to achieve optimized repression upon particle migration coalescence and Ostwald ripening, nevertheless, the microscale kinetics of migrating catalyst particles driven by the reaction remains unknown. In this work, the migration of nano-copper particles is investigated during hydrogen oxidation reaction by utilizing high spatiotemporal resolution of environmental transmission electron microscopy. It is shown that there exists a delicate correlation between the migration dynamics of nano-copper particles and the evolution of asymmetrically distributed Cu and Cu2O phases over the particle surface. It is found that the interplay of reduction and oxidation near the surface areas filled with Cu and Cu2O phases can facilitate the pressure gradient, which drives the migration of nano-particles. A driving force model is therefore established which is capable of qualitatively explaining the influences of reaction conditions such as temperature and hydrogen-to-oxygen ratio on the reaction-driven particle migration. This work adds a potential yet critical perspective to understanding particle migration and thus the nano-metal catalyst particle sintering in heterogeneous catalysis.

Molecular characterization and evaluation of novel management options for Burkholderia glumae BG1, the causative agent of panicle blight of rice (Oryza sativa L.).

BACKGROUND: Bacterial panicle blight, incited by Burkholderia glumae, has impacted rice production globally. Despite its significance, knowledge about the disease and the virulence pattern of the causal agent is very limited. Bacterial panicle blight is a major challenge in the rice-growing belts of North-western India, resulting in yield reduction. However, the management of B. glumae has become a challenge due to the lack of proper management strategies. METHODOLOGY AND RESULTS: Twenty-one BG strains have been characterized using the 16S rRNA and the gyrB gene-based sequence approach in the present study. The gyrB gene-based phylogenetic analysis resulted in geographic region-specific clustering of the BG isolates. The virulence screening of twenty-one BG strains by inoculating the pathogenic bacterial suspension of 1 × 10-8 cfu/ml at the booting stage (55 DAT) revealed the variation in the disease severity and the grain yield of rice plants. The most virulent BG1 strain resulted in the highest disease incidence (82.11%) and lowest grain yield (11.12 g/plant), and the least virulent BG10 strain resulted in lowest disease incidence of 18.94% and highest grain yield (24.62 g/plant). In vitro evaluation of various biocontrol agents and nano copper at different concentrations by agar well diffusion method revealed that nano copper at 1000 mg/L inhibited the colony growth of B. glumae. Under net house conditions, nano copper at 1000 mg/L reduced the disease severity to 21.23% and increased the grain yield by 20.91% (31.76 g per plant) compared to the positive control (COC 0.25% + streptomycin 200 ppm). Remarkably, pre-inoculation with nano copper at 1000 mg/L followed by challenge inoculation with B. glumae enhanced the activity of enzymatic antioxidants viz., Phenyl ammonia-lyase (PAL), Polyphenol oxidase (PPO) and Peroxidase (POX) and non-enzymatic antioxidant phenol. Additionally, we observed a substantial transcript level upregulation of six defense-related genes to several folds viz., OsPR2, OsPR5, OsWRKY71, OsPAL1, OsAPX1, and OsPPO1 in comparison to the pathogen control and healthy control. CONCLUSIONS: Overall, our study provides valuable insights into the potential and practical application of nano copper for the mitigation of bacterial panicle blight, offering promising prospects for commercial utilization in disease management.

Adsorption of dyestuff by nano copper oxide coated alkali metakaoline geopolymer in monolith and powder forms: Kinetics, isotherms and microstructural analysis.

To remove contaminants and pollutants from wastewater systems, adsorbents are widely used. Geopolymers offer a convenient alternative as adsorbents in the wastewater treatment system as they are low-cost, environmentally friendly, and safer. A new adsorbent material prepared by coating nano copper oxide on the surface of alkali-activated metakaolin showed a higher ability to remove methylene blue (MB) dye from wastewater, thus making them attractive in dye removal applications. First, nano copper oxide was prepared by sol gel method and metakaolin geopolymer was produced using sodium silicate solution having a Ms value of 1.1 (M). Afterwards, nano copper oxide (MC) was coated on the surface of the geopolymer. The ability of MB dye to bind to both pristine (Mp, MCp) and powder forms (Mpr, MCpr) of the geopolymer was evaluated. X-ray diffraction revealed that the halo found at 27.40°-31.077° (2θvalue) in both samples related to amorphous gel's composition and the major peaks of copper oxide in MCpr were sited at a 2θ value of 35.45° and 38.88°.The dye removal efficiency can be inferred from the increased adsorption capacity of 11.9 mg/g (Mp) and 14.4 mg/g (MCp) for the monolith form and 81.43 mg/g (Mpr) and 87.82 mg/g (MCpr) for the powder form. The adsorption of reused active sites was 73% for Mpr and 83% for MCpr up to the fifth cycle after regeneration by heat treatment at 400 °C. The models that best suited the adsorption data were pseudo-second-order and Freundlich isotherms, which indicated possible chemisorption with intra-particle diffusion. Furthermore, the binding energy is shifted to lower value in XPS spectra due to dye adsorption arising from electrostatic attraction. A higher electron density is formed due to interaction with an equal contribution of silanol Si-O-H and Si-O-Na/Cu(O1s). The adsorbents are effective over a wide pH range and their improved recycling capability increases their applications for a wide range of uses.

Autophagy and apoptosis mediated nano-copper-induced testicular damage.

Nano-copper has been increasingly employed in various products. In previous studies, we showed that nano-copper caused damage in the rat testis, but it remains unclear whether the toxic reaction can affect the reproductive function. In this study, following 28 d of exposure to nano-copper at a dose of 44, 88, and 175 mg/kg/day, there was a decrease in sperm quality, fructose content, and the secretion of sex hormones. Nano-copper also increased the level of oxidative stress, sperm malformation rate, and induced abnormal structural changes in testicular tissue. Moreover, Nano-copper upregulated the expression of apoptosis-related protein Bax and autophagy-related protein Beclin, and downregulated the expression of Bcl2 and p62. Furthermore, nano-copper (175 mg/kg) downregulated the protein expression of AMPK, p-AKT, mTOR, p-mTOR, p-4E-BP1, p70S6K, and p-p70S6K, and upregulated the protein expression of p-AMPK. Therefore, nano-copper induced damage in testicular tissues and spermatogenesis is highly related to cell apoptosis and autophagy by regulating the Akt/mTOR signaling pathway. In summary, excess exposure to nano-copper may induce testicular apoptosis and autophagy through AKT/mTOR signaling pathways, and damage the reproductive system in adult males, which is associated with oxidative stress in the testes.

Thermal interface material with graphene enhanced sintered copper for high temperature power electronics.

Sintered nano-copper is becoming a promising candidate as thermal interface material (TIM) for die attaching in high power electronics. It exhibits much higher thermal conductivity and operating temperature than conventional TIMs based on polymer and solder joints, and higher electromigration resistance and lower cost than sintered nano-silver TIM. However, the performance of existing sintered nano-copper is lower than expected because of high porosity resulted from poor sintering of copper particles with oxide shell. Here we demonstrate a method of improving the thermal conductivity of sintered copper by addition of graphene/Cu-CuxO with controllable diameter of ∼163 nm. The measured thermal conductivity of the sintered composite TIM is enhanced by up to 123.5% compared with that of sintered pure copper. It can be understood as a result of the formation of graphene heat transfer network in sintered TIM. In addition, the C-O-Cu bonds formed at the interface between graphene and copper nanoparticles are critical for improving thermal performance as well as electrical and mechanical performance of the TIM. The developed TIM can be widely used in high power electronic packaging especially for high temperature applications, including IGBT, SiC and GaN power devices.

Soil invertebrate toxicity and bioaccumulation of nano copper oxide and copper sulphate in soils, with and without biosolids amendment.

The fate, toxicity and bioaccumulation of copper oxide nanoparticles (nCuO) was investigated in soil, with and without biosolids amendment, through chronic exposures using the earthworm, Eisenia andrei, and the collembolan, Folsomia candida. The effects of copper sulphate (CuSO4) were included so as to compare the behavior of nCuO to a readily soluble counterpart. The fate of nCuO was evaluated through characterization of dissolved and nano-particulate fractions (via single particle ICP-MS) as well as extractable Cu2+ throughout the duration of select tests. Neither Cu form was particularly toxic to F. candida, but effects on E. andrei reproduction were significant in all treatments (IC50 range: 98 - 149 mg Cu kg-1 dry soil). There were no significant differences in toxicity between the Cu forms, nor in extractable Cu2+ activities, indicative that particle dissolution within the soil and, subsequent activity of Cu2+ was likely the primary mode of toxicity in the nCuO exposures. The presence of biosolids did not significantly alter toxicity of nCuO, but did affect Cu2+ activity over time. Bioaccumulation of total Cu in E. andrei when exposed to nCuO (kinetic bioaccumulation factor (BAFk): 0.80 with biosolids and 0.81 without) was lower than exposure to CuSO4 (BAFk: 2.31 with biosolids and 1.12 without). Enhanced dark-field hyperspectral imaging showed accumulation of nCuO along the epidermis and gut of E. andrei, with trace amounts observed in muscle and chloragogenous tissue, providing evidence of nCuO translocation within the organism. The present study demonstrates that the current risk assessment approach for trace metals in the environment, based on substance solubility and bioavailability of the dissolved free ion, are applicable for nCuO exposure to soil invertebrates, but that the rate of particle dissolution in different soil environments is an important factor for consideration.

Autophagy was activated against the damages of placentas caused by nano-copper oral exposure.

Nano-copper (nano-Cu) is widely used in the pharmaceutical field as well as a feed additive for animals owing to its unique physicochemical characteristics and bioactivities. In our previous study, nano-Cu was found to hamper fetal development; however, the toxicity of nano-Cu and its effects in placental function have not been elucidated. Therefore, we investigated the toxic effects of nano-Cu using rat placenta. Pregnant Sprague-Dawley rats were orally exposed to different copper sources from the third day of gestation (GD 3) to GD 18. We found that nano-Cu (180 mg/kg) and CuCl2.2 H2O increased the accumulation of copper. Besides, nano-Cu and CuCl2.2 H2O disrupted the placental morphology and induced oxidative stress. Micro-copper (micro-Cu) caused similar toxicity in the placenta, but its effects were weaker than that of nano-Cu and CuCl2.2 H2O. In addition, exposure to nano-Cu (180 mg/kg) and CuCl2.2 H2O induced inflammation in the rat placenta. Furthermore, nano-Cu, micro-Cu, and CuCl2.2 H2O upregulated the expression of the autophagy-related proteins, Beclin-1 and LC3 II/ LC3 I, and downregulated that of p62. Moreover, nano-Cu, micro-Cu, and CuCl2.2 H2O downregulated the protein expression of PI3K, p-AKT/AKT, and p-mTOR/mTOR in rat placentas, whereas the protein expression of p-AMPK/AMPK was upregulated. Taken together, our data indicated that prenatal exposure to nano-Cu induced autophagy via the PI3K/AKT/mTOR and AMPK/mTOR pathways, which associated with oxidative stress and inflammation in rat placenta.

Nano-copper enhanced flexible device for simultaneous measurement of human respiratory and electro-cardiac activities.

BACKGROUND: Dysfunction of human respiratory and electro-cardiac activities could affect the ability of the heart to pump blood and the lungs to inhale oxygen. Thus, a device could simultaneously measure electro-cardiac signal and respiratory pressure could provide vital signs for predicting early warning of cardio-pulmonary function-related chronic diseases such as cardiovascular disease, and respiratory system disease. RESULTS: In this study, a flexible device integrated with piezo-resistive sensing element and voltage-sensing element was developed to simultaneously measure human respiration and electro-cardiac signal (including respiratory pressure, respiration frequency, and respiration rhythm; electro-cardio frequency, electro-cardio amplitude, and electro-cardio rhythm). When applied to the measurement of respiratory pressure, the piezo-resistive performance of the device was enhanced by nano-copper modification, which detection limitation of pressure can reduce to 100 Pa and the sensitivity of pressure can achieve to 0.053 ± 0.00079 kPa-1. In addition, the signal-to-noise ratio during bio-electrical measurement was increased to 10.7 ± 1.4, five times better than that of the non-modified device. CONCLUSION: This paper presents a flexible device for the simultaneous detection of human respiration and cardiac electrical activity. To avoid interference between the two signals, the layout of the electrode and the strain sensor was optimized by FEA simulation analysis. To improve the piezo-resistive sensitivity and bio-electric capturing capability of the device, a feather-shaped nano-copper was modified onto the surface of carbon fiber. The operation simplicity, compact size, and portability of the device open up new possibilities for multi-parameter monitoring.

Cadmium-Sensitive Measurement Using a Nano-Copper-Enhanced Carbon Fiber Electrode.

Enrichment of cadmium ion (Cd2+) from the environment may lead to kidney disease and weakened immunity in the body. Current techniques are not convenient enough to measure Cd2+ concentration in the environment due to low sensitivity and poor linear range. In this paper, a new measurement technique is proposed using a new sensing electrode made of nano-copper-enhanced carbon fiber. Nano-copper was deposited onto the surface of carbon fiber to enhance the current concentration and mass transfer rate of Cd2+ during measurement, which improved the electrochemical detection sensitivity significantly (by up to 3.7 × 108 nA/nM) and broadened the linear range to 10~105 nM. This device provides a low-cost solution for measuring Cd2+ concentration in the environment.

Effects and Mechanism of Nano-Copper Exposure on Hepatic Cytochrome P450 Enzymes in Rats.

Although nano-copper is currently used extensively, the adverse effects on liver cytochrome P450 (CYP450) enzymes after oral exposure are not clear. In this study, we determined the effects and mechanisms of action of nano- and micro-copper on the expression and activity of CYP450 enzymes in rat liver. Rats were orally exposed to micro-copper (400 mg/kg), Cu ion (100 mg/kg), or nano-copper (100, 200 and 400 mg/kg) daily for seven consecutive days. Histopathological, inflammatory and oxidative stress were measured in the livers of all rats. The mRNA levels and activity of CYP450 enzymes, as well as the mRNA levels of select nuclear receptors, were determined. Exposure to nano-copper (400 mg/kg) induced significant oxidative stress and inflammation relative to the controls, indicated by increased levels of interleukin (IL)-2, IL-6, interferon (IFN)-γ, macrophage inflammatory protein (MIP-1), total antioxidant capacity (T-AOC), malondialdehyde (MDA), inducible nitric oxide synthase (iNOS) and nitric oxide (NO) after exposure. The levels of mRNA expression of pregnane X receptor (PXR), constitutive androstane receptor (CAR) and aryl hydrocarbon receptor (AHR) were significantly decreased in 400 mg/kg nano-copper treated rats. Nano-copper activated the expression of the NF-kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription (STAT)3 signaling pathways. Nano-copper decreased the mRNA expression and activity of CYP 1A2, 2C11, 2D6, 2E1 and 3A4 in a dose-dependent manner. The adverse effects of micro-copper are less severe than those of nano-copper on the CYP450 enzymes of rats after oral exposure. Ingestion of large amounts of nano-copper in animals severely affects the drug metabolism of the liver by inhibiting the expression of various CYP450 enzymes, which increases the risk of drug-drug interactions in animals.

Metabolic parameters in young turkeys fed diets with different inclusion levels of copper nanoparticles.

The aim of this study was to verify the hypothesis postulating that the supplementation of turkey diets with Cu nanoparticles can lower dietary inclusion levels of Cu without compromising the growth rate and antioxidant status of turkeys. The experiment was carried out on 648 one-day-old Hybrid Converter turkeys divided into 6 groups with 6 replicates per group, in a two-factorial design with 3 dietary inclusion levels of Cu (20, 10 and 2 mg/kg) and 2 dietary sources of Cu - copper sulfate (Cu-SUL) and Cu nanoparticles (Cu-NP). At 42 days of age, blood samples were collected from 2 birds per replicate (12 birds per group), after slaughter livers were collected for analyses. Blood and liver samples were assayed for: Cu, Zn, Ca, P, Mg, GLU, TP, ALB, UREA, TAG, TC, UA, ALT, AST, ALT, GGT, ALP, SOD, GPx, CAT, VIT C, FRAP, GSH+GSSG, LOOH, MDA. The results of this experiment demonstrate that a decrease in the dietary inclusion levels of Cu from 10 mg/kg to 2 mg/kg does not compromise the growth performance of turkeys, but weakens antioxidant defense mechanisms. A Cu dose of 20 mg/kg induces oxidation reactions and has a much more inhibitory effect on the antioxidant defense system than dietary Cu content of 2 mg/kg. In turkeys, dietary supplementation with Cu-NP has a more beneficial effect on carbohydrate metabolism and antioxidant status compared with Cu-SUL. The results of analyses examining the antioxidant and metabolic status of young turkeys indicate that 10 mg/kg is the optimal dietary inclusion level of Cu.

Combined ecotoxicity of binary zinc oxide and copper oxide nanoparticles to Scenedesmus obliquus.

A combined ecotoxicity study was carried out with nano-zinc oxide (nZnO) and nano-copper oxide (nCuO) to freshwater algae Scenedesmus obliquus. Concentration-response analysis indicated that the dissolved metal fraction was not the major source of individual and combined toxicity of the metal-oxide nanoparticles (MONPs). Moreover, the contribution of the nCuO (based on metallic mass) to the combined toxicity was greater than that of the nZnO. The observed combined toxicity can be predicted by the pharmacological concepts of concentration addition (CA) and independent action (IA). Combined toxicity prediction (in terms of median effect concentration) based on both concepts tends to overestimate the overall observed toxicity of the MONP mixtures. CA was more accurate for predicting the combined toxicity than IA. It may be concluded that CA gives a valid estimation of the overall ecotoxicity for mixtures comprising of similar acting MONPs.

Study on the Technology and Properties of Green Laser Sintering Nano-Copper Paste Ink.

With the rapid development of integrated circuits, glass substrates are frequently utilized for prototyping various functional electronic circuits due to their superior stability, transparency, and signal integrity. In this experiment, copper wire was printed on a glass substrate using inkjet printing, and the electronic circuit was sintered through laser irradiation with a 532 nm continuous green laser. The relationship between resistivity and microstructure was analyzed after laser sintering at different intensities, scanning speeds, and iterations. The experimental results indicate that the conductivity of the sintered lines initially increases and then decreases with an increase in laser power and scanning speed. At the same power level, multiple sintering runs at a lower scanning speed pose a risk of increased porosity leading to reduced conductivity. Conversely, when the scanning speed exceeds the optimal sintering speed, multiple sintering runs have minimal impact on porosity and conductivity without altering the power.

Disruption of bacterial biofilms by a green synthesized artemisinin nano-copper nanomaterial.

Bacterial biofilms are associated with antibiotic resistance and account for ∼80% of all bacterial infections. In this study, we explored novel nanomaterials for combating bacteria and their biofilms. Artemisinin nano-copper (ANC) was synthesized using a green synthesis strategy, and its shape, size, structure, elemental composition, chemical valence, zeta potential, and conductivity were characterized using transmission electron microscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, zeta potential, and dynamic light scattering. The results showed that ANC was successfully synthesized utilizing a liquid phase chemical reduction method using chitosan as a modified protectant and l-ascorbic acid as a green reducing agent. The stability of ANC was evaluated using dynamic light scattering. The results showed that the particle size of ANC at different concentrations was comparable to that of the original solution after 7 days of storage, and there was no significant change in the polydispersity index (P > 0.05). The antibacterial effects of ANC on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were determined by disc diffusion and broth dilution methods. The results demonstrated that ANC inhibited and killed E. coli and S. aureus. The effect of ANC on bacterial biofilms was investigated using crystal violet staining, scanning electron microscopy, laser confocal microscopy, and quantitative polymerase chain reaction. The results showed that ANC treatment was able to destroy bacterial biofilms and downregulate biofilm- and virulence-related genes in E. coli (HlyA, gyrA, and F17) and S. aureus (cna, PVL, ClfA, and femB). Green-synthesized ANC possesses excellent antibiofilm properties and is expected to exhibit antibacterial and antibiofilm properties.

Nano-copper Enhances Gene Regulation of Non-specific Immunity and Antioxidative Status of Fish Reared Under Multiple Stresses.

Arsenic pollution, water temperature, and pH are the major concern for aquaculture. Moreover, the aim of the present investigation was to delineate the role of nano-copper (Cu-NPs) in the mitigation of arsenic toxicity, high temperature (34 °C) and low pH (6.5) stress on Pangasianodon hypophthalmus. Four isonitrogenous and isocaloric experimental diets of Cu-NPs at 0, 1.0, 1.5 and 2.0 mg kg-1 were formulated and prepared. Arsenic pollution, low pH and high temperature stress significantly reduced the anti-oxidative status (super oxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase), lipid peroxidation, total anti-oxidative capacity and lipid profiling (cholesterol, total lipid, phospholipid, very low-density lipoprotein and triglyceride). Further, the supplementation of Cu-NPs at 1.5 and 1.0 mg kg-1 diets noticeably improve the anti-oxidant status and capacity. The stressors groups (As + pH + T, As + T and As) significantly reduced fish immunity viz. albumin, globulin, total protein, albumin globulin ratio (A:G ratio), myeloperoxidase, respiratory burst activities, tumor necrosis factor, total immunoglobulin, and interleukin. Whereas supplementation of Cu-NPs at 1.5 and 1.0 mg kg-1 diets improved the immunity of the fish reared under multiple stresses (As + pH + T). Tail DNA %, DNA damage-inducible protein (DDIP) and inducible nitric oxide (iNOS) synthase gene expression were significantly enhanced with exposure to arsenic, low pH and high temperature but supplementation of Cu-NPs protects the tissues against DNA damage and improved the gene expression of iNOS and DDIP. Cu-NPs at 1.5 and 1.0 mg kg-1 diets significantly enhanced the body weight gain %, protein efficiency ratio, specific growth rate, daily growth index, relative feed intake and reduced the feed conversion ratio. Whereas, the growth-related gene expression such as myostatin (MYST), somatostatin (SMT) was downregulated by Cu supplementation and upregulated the gene expression of growth hormone regulator 1 and ß (GHR1 and GHR ß) and growth hormone (GH) gene in fish. Dietary Cu-NPs supplementation protects the fish against bacterial infection and enhances arsenic detoxification in different tissues. The present investigation revealed that supplementation of Cu-NPs at 1.5 and 1.0 mg kg-1 diet has the potential to mitigate multiple stress (As + pH + T) in fish.

Manufacturing of Aluminum Nano-Composites Reinforced with Nano-Copper and High Graphene Ratios Using Hot Pressing Technique.

In this study, the nano-aluminum powder was reinforced with a hybrid of copper and graphene nanoplatelets (GNPs). The ratios of GNPs were 0 wt%, 0.4 wt%, 0.6 wt%, 1.2 wt% and 1.8 wt%. To avoid the reaction between aluminum and graphene and, consequently, the formation of aluminum carbide, the GNP was first metalized with 5 wt% Ag and then coated with the predetermined 15 wt% Cu by the electroless coating process. In addition, the coating process was performed to improve the poor wettability between metal and ceramic. The Al/(GNPs-Ag)Cu nanocomposites with a high relative density of 99.9% were successfully prepared by the powder hot-pressing techniques. The effects of (GNPs/Ag) and Cu on the microstructure, density, hardness, and compressive strength of the Al-Cu nanocomposite were studied. As a result of agitating the GNPs during the cleaning and silver and Cu-plating, a homogeneous distribution was achieved. Some layers formed nano-tubes. The Al4C3 phase was not detected due to coating GNPs with Cu. The Cu9Al4 intermetallic was formed during the sintering process. The homogeneous dispersion of Cu and different ratios of GNs, good adhesion, and the formation of the new Cu9Al4 intermetallic improved in hardness. The pure aluminum sample recorded 216.2 HV, whereas Al/Cu reinforced with 1.8 GNs recorded 328.42 HV with a 51.9% increment. The compressive stress of graphene samples was improved upon increasing the GNPs contents. The Al-Cu/1.8 GNs sample recorded 266.99 MPa.

Nano-copper ions assembled cellulose-based composite with antibacterial activity for biodegradable personal protective mask.

The current SARS-CoV-2 pandemic has resulted in the widespread use of personal protective equipment, particularly face masks. However, the use of commercial disposable face masks puts great pressure on the environment. In this study, nano-copper ions assembled cotton fabric used in face masks to impart antibacterial activity has been discussed. To produce the nanocomposite, the cotton fabric was modified by sodium chloroacetate after its mercerization, and assembled with bactericidal nano-copper ions (about 10.61 mg·g-1) through electrostatic adsorption. It demonstrated excellent antibacterial activity against Staphylococcus aureus and Escherichia coli because the gaps between fibers in the cotton fabric allow the nano-copper ions to be fully released. Moreover, the antibacterial efficiency was maintained even after 50 washing cycles. Furthermore, the face mask constructed with this novel nanocomposite upper layer exhibited a high particle filtration efficiency (96.08% ± 0.91%) without compromising the air permeability (28.9 min·L-1). This green, economical, facile, and scalable process of depositing nano-copper ions onto modified cotton fibric has great potential to reduce disease transmission, resource consumption, and environmental impact of waste, while also expanding the range of protective fabrics.

The effects of copper ions and copper nanomaterials on the output of amino acids from marine microalgae.

In this study, the marine microalgae Skeletonema costatum and Nitzschia closterium were exposed to different forms of copper, such as a metal salt (Cu2+), a nano-metal (nano-Cu), and nano-metal oxide (nano-CuO). During a 96-h exposure to nanoparticles (NPs) and salt, the cell number, Cu2+ concentration in the culture medium, morphology, and intracellular amino acids were measured to assess the toxicity of the copper materials and the toxicity mechanism of the NPs. As results, the toxicity of Cu2+, nano-Cu, and nano-CuO to marine phytoplankton decreased in order. The EC50 values of Cu2+ and nano-Cu for S. costatum and N. closterium ranged from 0.356 to 0.991 mg/L and 0.663 to 2.455 mg/L, respectively. Nano-Cu inhibits the growth of marine phytoplankton by releasing Cu2+; however, nano-CuO is harmful to microalgae because of the effect of NPs. The secretion of extracellular polymeric substances by microalgae could also affect the toxicity of nano-Cu and nano-CuO to microalgae. S. costatum was more sensitive to copper than N. closterium. Cu2+, nano-Cu, and nano-CuO all reduced per-cell amino acids and the total output of algae-derived amino acids by affecting the growth of the phytoplankton. This study helps to understand the risk assessment of nano-Cu and nano-CuO to marine microalgae.

Effects of Nano-copper Oxide on Antioxidant Function of Copper-Deficient Kazakh Sheep.

Kazakh sheep are vital to the production system of the Barkol prairie. The purpose of this study was to determine the effect of nano-copper oxide (Nano-Cu2O) on the antioxidant system of Cu-deficient Kazakh sheep in the Barkol prairie in Xinjiang, China. We analyzed mineral contents in soil, forage, and animal tissues. Blood parameters were also measured at the same time. The results showed that compared with healthy grassland, the Cu content in the soil and forage in Cu-deficient pastures was significantly lower than that in healthy grassland (P < 0.01). The Cu content in the blood, wool, and liver of Cu-deficient Kazakh sheep was significantly lower than that of healthy animals (P < 0.01). After Kazakh sheep were supplemented with Nano-Cu2O or CuSO4, the blood Cu concentration increased significantly (P < 0.01). From the 5th day, the Cu content of the Nano-Cu2O group was significantly higher than that of the CuSO4 group. The levels of hemoglobin (Hb), erythrocyte count (RBC), and packed cell volume (PCV) in the two experimental groups were significantly higher than those in Cu-deficient Kazakh sheep (P < 0.01). Compared with Cu-deficient Kazakh sheep, the serum ceruloplasmin (Cp) level of the two experimental groups increased significantly (P < 0.01), while the serum lactate dehydrogenase (LDH), alkaline phosphatase (AKP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) decreased significantly (P < 0.01). Compared with Cu-deficient Kazakh sheep, the activities of serum superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and total antioxidant capacity (T-AOC) in Nano-Cu2O and CuSO4 groups increased significantly (P < 0.01), while the level of serum malondialdehyde (MDA) decreased significantly (P < 0.01). Therefore, Nano-Cu2O could not only significantly increase the Cu content in the blood of Cu-deficient Kazakh sheep, but also greatly improve the antioxidant capacity.

Desulfurization of Cu-Fe Alloy Obtained from Copper Slag and the Effect on Form of Copper in Alloy.

In order to realize the high-value utilization of copper slag, a process for preparing Cu-Fe alloy through the reduction of copper slag is proposed. The sulfur in the alloy exists in the form of matte inclusions, which is different from sulfur in molten iron. The reaction of CaO with Cu2S is difficult. It is necessary to add a reducing agent to promote desulfurization. To avoid the introduction of other elements, Fe-Mn and CaC2 additions were used as desulfurizers for the desulfurization of Cu-Fe alloy. The thermodynamics of the desulfurization reaction were calculated and the experimental process was studied. It was found that the Gibbs free energy of desulfurization reactions was negative for Fe-Mn and that CaC2 can reduce the sulfur in the alloy to 0.0013% and 0.0079%, respectively. The desulfurization process affected the shape of copper in the alloy. Part of copper in this alloy exists in the form of nano-copper spheres, and the size of the spheres is found to increase after desulfurization. Reducing agents can facilitate the desulfurization process of stable sulfides.