Addition Of Copper Research Articles

Two- and three-component alloys nanowires: correlation of structural and magnetic properties

Several types of nanowires (NWs) made of alloys of various compositions obtained by the method of matrix synthesis based on track membranes have been studied. Electrolytes were selected to obtain NWs of the desired composition. The control of electrodeposition by chronoamperograms made it possible to systematically change the geometric parameters and morphology. The topographies of the resulting NW arrays and their elemental composition were studied using electron microscopy with an X-ray spectral analyzer. The magnetic properties of the samples were studied on a vibrating magnetometer. The structures of binary alloys were studied: for NWs of FeCo alloys, the dependence of the coercive force on the composition was studied. The obtained dependence has two maxima --- at an equiatomic composition and at a cobalt content of about 90%. For Fe0.3Co0.7 NWs, a sharp increase in the coercive force with decreasing diameter is shown. It is assumed that this effect is due to the formation of single-domain crystallites, the processes of magnetization reversal of which are associated with a uniform rotation of the magnetization. For NWs made of FeNi alloys, the influence of the aspect ratio on the coercive force has been proved. Ternary alloys of the FeCoCu system have been studied: it has been shown that the addition of copper significantly increases the coercive force, which reaches a maximum at a copper content of about 5%. The obtained X-ray data suggest that the effect of an increase in the coercive force is associated with the formation of fine-grained inclusions based on copper, which lead to effective deceleration of the domain walls. The data obtained expand the range of possibilities for controlling the magnetic properties of NW arrays obtained by the method of matrix synthesis. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, coercive force. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, coercive force.

Нанопроволоки из двух- и трехкомпонентных сплавов: корреляция структурных и магнитных свойств

Several types of nanowires (NWs) made of alloys of various compositions obtained by the method of matrix synthesis based on track membranes have been studied. Electrolytes were selected to obtain NWs of the desired composition. The control of electrodeposition by chronoamperograms made it possible to systematically change the geometric parameters and morphology. The topographies of the resulting NW arrays and their elemental composition were studied using electron microscopy with an X-ray spectral analyzer. The magnetic properties of the samples were studied on a vibrating magnetometer. The structures of binary alloys were studied: for NWs of FeCo alloys, the dependence of the coercive force on the composition was studied. The obtained dependence has two maxima - at an equiatomic composition and at a cobalt content of about 90%. For Fe0.3Co0.7 NWs, a sharp increase in the coercive force with decreasing diameter is shown. It is assumed that this effect is due to the formation of single-domain crystallites, the processes of magnetization reversal of which are associated with a uniform rotation of the magnetization. For NWs made of FeNi alloys, the influence of the aspect ratio on the coercive force has been proved. Ternary alloys of the FeCoCu system have been studied: it has been shown that the addition of copper significantly increases the coercive force, which reaches a maximum at a copper content of about 5%. The obtained X-ray data suggest that the effect of an increase in the coercive force is associated with the formation of fine-grained inclusions based on copper, which lead to effective deceleration of the domain walls. The data obtained expand the range of possibilities for controlling the magnetic properties of NW arrays obtained by the method of matrix synthesis. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, coercive force.

Growth of complex crystal on biopolymer surface: Synthesis and characterization

Although the physical properties of polymers already have been modified by changing different synthetic parameters, the effect of the crystallization by the doping is still rarely explored. In this work, a facile synthesis of composite chitosan film with copper L-valinate crystal (CHLVCu) was investigate. Composite films were prepared by the addition of copper II L‐valine crystals (LVCu) in concentrations of 0.05, and 0.1 in 0.2% chitosan solution. The composite film of LVCu crystal dispersed in CH solution has been successfully obtained by the technique of solvent slow evaporation at low temperature. CHLVCu composite films are crystalline stabilizing the trans-LVCu phase. Homogeneity and low thermal stability have been proven by thermal measurements. The crystal growth takes place in the polymer surface. In addition, it is noteworthy that to the best of our knowledge, crystals complex of the LVCu has not been used as incorporate chitosan film and study has reported changes in physical properties composite film. The future this film can be application in area biomedical and technological.

Effect of Copper (II) Sulfate on the Properties of Urea Formaldehyde Adhesive.

The purpose of this work is to investigate the effects of copper (II) sulfate on the formaldehyde release and the mechanical properties of urea formaldehyde (UF) adhesive. Copper (II) sulfate has been used as a formaldehyde scavenger in UF resin, and its effects on the physical and chemical properties of UF adhesive have been studied. Moreover, the mechanical properties and formaldehyde release of plywood prepared with modified UF resin have been determined. The UF resin has been characterized by Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). FTIR spectra showed that the addition of copper (II) sulfate to the UF resin does not affect the IR absorptions of its functional groups, implying that the structure of UF is not modified. Further results showed that the free formaldehyde content of the UF resin incorporating 3% copper (II) sulfate was 0.13 wt.%, around 71% lower than that of the untreated control UF adhesive. With a copper (II) sulfate content of 3%, the formaldehyde release from treated plywood was 0.74 mg·L−1, around 50% lower than that from the control UF adhesive, and the bonding strength reached 1.73 MPa, around 43% higher than that of the control.

Distinct comammox Nitrospira catalyze ammonia oxidation in a full-scale groundwater treatment bioreactor under copper limited conditions

Microbial ammonia oxidation is the initial nitrification step used in biological nitrogen-removal during water treatment processes, and the discovery of complete ammonia-oxidizing (comammox) bacteria added a novel member to this functional group. It is important to identify and understand the predominant microorganisms responsible for ammonium removal in biotechnological process design and optimization. In this study, we used a full-scale bioreactor to treat ammonium in groundwater (9.3 ± 0.5 mg NH4+-N/L) and investigated the key ammonia-oxidizing prokaryotes present. The groundwater ammonium was stably and efficiently oxidized throughout ∼700 days of bioreactor operation. 16S rRNA gene amplicon sequencing of the bioreactor community showed a high abundance of Nitrospira (12.5–45.9%), with the dominant sequence variant (3.5–37.8%) most closely related to Candidatus Nitrospira nitrosa. Furthermore, analyses of amoA, the marker gene for ammonia oxidation, indicated the presence of two distinct comammox Nitrospira populations, however, the relative abundance of only one of these populations was strongly correlated to ammonia oxidation rates and was robustly expressed. After 380 days of operation copper wires were immersed into the reactor at 0.04–0.06 m2/m3 tank, which caused a gradual abundance increase of one discrete comammox Nitrospira population. However, further increase of the copper dosing (0.08 m2/m3 tank) inverted the most abundant ammonia-oxidizing population to Nitrosomonas sp. These results indicate that comammox Nitrospira were capable of efficient ammonium removal in groundwater without exogenous nutrients, but copper addition can stimulate comammox Nitrospira or lead to dominance of Nitrosomonas depending on dosage.

Microstructural refinement and tensile properties enhancement of Al-10Mg2Si cast alloys by copper addition

The effect of Cu addition on the microstructural evolution and mechanical properties of hypoeutectic Al-10Mg2Si alloys was investigated. It was found that Cu addition could effectively refine the primary α-Al grain. Simultaneously, the coarse eutectic Mg2Si was also modified to be fine coral-like. The constitutional supercooling and the multiple nanosized precipitating layers at the edge of the eutectic Mg2Si cause the branching and refining of the eutectic Mg2Si through effectively restricting the growth of eutectic Mg2Si, while the Cu-rich clusters and nanosized precipitates on the surface of the end of the eutectic Mg2Si prevent the diffusion of the solute atoms such as Al, Mg and Si, and the growth of eutectic Mg2Si grains is physically limited, resulting in the decrease of the length of eutectic Mg2Si. The strength and ductility of the Cu-added Al-10Mg2Si alloys were simultaneously improved, and the fracture failure mode transforms from brittle failure to ductile failure. The mechanism of mechanical properties enhanced by Cu addition was discussed.

Effect of Copper and Chromium Addition on the Mechanical and Wear Resistance of Tempered Hypoeutectic Grey Cast Iron used in Crusher Applications

Effect of Copper and Chromium Addition on the Mechanical and Wear Resistance of Tempered Hypoeutectic Grey Cast Iron used in Crusher Applications

N2O Formation during NH3-SCR over Different Zeolite Frameworks: Effect of Framework Structure, Copper Species, and Water

The formation characteristics of N2O were investigated with respect to copper-functionalized zeolites, i.e., Cu/SSZ-13 (CHA), Cu/ZSM-5 (MFI), and Cu/BEA (BEA) and compared with the corresponding zeolites in the H form as references to elucidate the effect of the framework structure, copper addition, and water. Temperature-programmed reduction with hydrogen showed that the CHA framework has a higher concentration of Cu2+ (Z2Cu) compared to MFI and BEA. The characterizations and catalyst activity results highlight that CHA has a framework structure that favors high formation of ammonium nitrate (AN) in comparison with MFI and BEA. Moreover, AN formation and decomposition were found to be promoted in the presence of Cu species. On the contrary, lower N2O formation was observed from Cu/CHA during standard and fast SCR reactions, which is proposed to be due to highly stabilized AN inside the zeolite cages. On the other hand, significant amounts of N2O were released during heating due to decomposition of AN, implying pros and cons of AN stability for Cu/CHA with possible uncontrolled N2O formation during transient conditions. Additionally, important effects of water were found, where water hinders AN formation and increases the selectivity for decomposition to NO2 instead of N2O. Thus, less available AN forming N2O was observed in the presence of water. This was also observed in fast SCR conditions where all Cu/zeolites exhibited lower continuous N2O formation in the presence of water.

Tuning lattice defects to facilitate the catalytic performance of Ni–Cu–O hybrid nanoparticles towards methane oxidation

Herein, an attempt was made to modulate the properties of NiO oxides towards methane combustion. For this purpose, appropriate content of copper was introduced into the NiO lattice to generate Cu–Ni solid solution, in view of the similarities in atomic-size and electronegativity between copper and nickel. This delivered more unsaturated nickel atoms and reduced the nanoparticle size of NiO, generating more lattice defects. Also, the oxygen binding energy was significantly lowered stemming from the creation of Ni–O–Cu linkage, and the interaction between CuO and NiO. Consequently, larger amount of active surface adsorbed oxygen sites were given and the reducibility of NiO was considerably enhanced for bimetallic systems compared with pure NiO. Meanwhile, the surface acid-base properties were adjusted over samples after the addition of copper, attributed to the charge redistribution among the oxygen and metal atoms. These effects accounted for the preferred activity, water-resistance, and durability for Cu-promoted NiO catalysts.

Copper catalyzed decarboxylative coupling between coumarin 3-carboxylic acid and 4-thiazolidinones

An efficient copper-catalyzed decarboxylative cross coupling reaction of coumarin 3-carboxylic acid with 4-thiazolidinones has been developed. The described strategy operated smoothly via subsequent decarboxylation and radical addition in the presence of copper catalyst and oxidant. Various coumarinyl-4-thiazolidinone derivatives were obtained easily in moderate to good yield by employing this strategy. Substrate scope and optimization have been carried out appropriately. Optimization was carried out through various copper catalyst, oxidants, and additives.

Oxidative destruction of anionite AV-17×8 using the Fenton reaction

The kinetic studies of AV-17×8 strongly basic anionite’s oxidative destruction using the Fenton reaction have been carried out. The effect of the process’s temperature and the concentration of catalysts of iron(II) sulfate or copper(II) sulfate on the oxidation of anion-exchange resin with hydrogen peroxide is estimated. With an increase in temperature in the range of 323–348 K, a regular increase in the effective rate constant of oxidative anionite destruction is observed when using iron(II) sulfate by 1.5 times, and when using copper(II) sulfate – by 22 times. It was found that the obtained values of the activation energy of the anion exchanger’s oxidation with the addition of copper(II) sulfate are 124.3–115.7 kJ/mol and are characteristic of the process proceeding in the kinetic region. The nature of the change in the surface morphology of the anionite granules in the process of oxidative decomposition has been revealed.

The Copper Influence into Physical and Mechanical Properties of the Al-5Si Alloy

The microstructure and the hardness due to addition of copper of the Al-Si-Zn-Mg-Cu Alloy have been investigated. The copper has been varied from 0 wt.%– 4.9 wt.% in order to see how the microstructure and the hardness of the alloy change. The Heat treatment at temperature 510 o C during 5 hours and then cooling to ambient temperature, have done to foster the dissolution of copper in the crystal and then precipitate during cooling. The results show that the alloying element form a phase distributed in the matrix of the alloy. Increasing the content of the copper makes the form of the second phase smaller and at the matrix show fine particle distributed mostly entire of the surface. The hardness of the alloy increase as the copper content increase. The increase in hardness might come from the fine particle distributed in the matrix. The onset, endset and melting temperature tend to decrease as the copper content increase.

Influence of selective laser treatment on thermal stability of Ti3AlC2 and Ti3AlC2/Cu powders

Commercial Ti3AlC2 MAX phase powder and Ti3AlC2/Cu powder blends were used to obtain bulk materials using selective laser sintering/melting technique. In the present work, the influence of laser line energy on the stability of Ti3AlC2 composition was investigated. The structure of MAX phases was better maintained in composites with copper addition, forming a metal matrix composite with a copper matrix and Ti3AlC2 inclusions.

Effect of Functionalized Multi-Walled Carbon Nanotubes on Preparation of High Strength and Conductive Copper-CNTs Composites by Electrodeposition

Functionalized multiwalled carbon nanotubes (MWCNTs)-reinforced copper (Cu) composites were prepared by the combination of electrowinning and hot-pressing sintering and cold rolling process. The influence of the functionalization of MWCNTs on the strength and electrical properties of MWCNTs/Cu composites was studied. Functional group was introduced to increase the wetting of water electrolytes, improve the poor wettability of MWCNTs and form a highly active surface suitable for the preparation of MWCNTs/Cu composites by electro-deposition, enabling MWCNTs to be evenly dispersed in Cu matrix. Studies have shown that the addition of 1% of functionalized MWCNTs composite can increase the tensile strength by 6% and 165% compared with the addition of unfunctionalized and pure copper. It’s worth noting that the increase of oxygen-containing functional group brought about by functionalized MWCNTs did not significantly reduce the electrical properties of composites. The main reason for this is the good dispersion of the treated MWCNTs in Cu matrix and the bridging for electronic transmission, ensuring that the high electrical properties of MWCNTs/Cu composites are just slightly lower than those of electrolytic pure copper (99.92% IACS).

Copper‐Catalyzed Difluoromethylation of Alkyl Iodides Enabled by Aryl Radical Activation of Carbon–Iodine Bonds

AbstractThe engagement of unactivated alkyl halides in copper‐catalyzed cross‐coupling reactions has been historically challenging, due to their low reduction potential and the slow oxidative addition of copper(I) catalysts. In this work, we report a novel strategy that leverages the halogen abstraction ability of aryl radicals, thereby engaging a diverse range of alkyl iodides in copper‐catalyzed Negishi‐type cross‐coupling reactions at room temperature. Specifically, aryl radicals generated via copper catalysis efficiently initiate the cleavage of the carbon–iodide bonds of alkyl iodides. The alkyl radicals thus generated enter the copper catalytic cycles to couple with a difluoromethyl zinc reagent, thus furnishing the alkyl difluoromethane products. This unprecedented Negishi‐type difluoromethylation approach has been applied to the late‐stage modification of densely functionalized pharmaceutical agents and natural products.

Copper-Catalyzed Difluoromethylation of Alkyl Iodides Enabled by Aryl Radical Activation of Carbon-Iodine Bonds.

The engagement of unactivated alkyl halides in copper-catalyzed cross-coupling reactions has been historically challenging, due to their low reduction potential and the slow oxidative addition of copper(I) catalysts. In this work, we report a novel strategy that leverages the halogen abstraction ability of aryl radicals, thereby engaging a diverse range of alkyl iodides in copper-catalyzed Negishi-type cross-coupling reactions at room temperature. Specifically, aryl radicals generated via copper catalysis efficiently initiate the cleavage of the carbon-iodide bonds of alkyl iodides. The alkyl radicals thus generated enter the copper catalytic cycles to couple with a difluoromethyl zinc reagent, thus furnishing the alkyl difluoromethane products. This unprecedented Negishi-type difluoromethylation approach has been applied to the late-stage modification of densely functionalized pharmaceutical agents and natural products.

Opportunities of copper addition in CH3NH3PbI3 perovskite and their photovoltaic performance evaluation

Perovskite solar cells (PSCs) have encountered a fulgurant development in their power-conversion efficiency (PCEs) generation in the drive to provide a facile, cheap and clean source of energy over just a few years. The most efficient PSCs are fabricated using CH3NH3PbI3 (MAPbI3) perovskite. However, being a promising photovoltaic (PV) performance piloted by MAPbI3, Pb-toxicity and poor stability obstructs the progress of PSCs in PV technology. In this regard, replacing Pb with some environmentally friendly, cheaper, and similar optoelectronic behaviour related alternative material or element is highly desirable. In this work, an attempt was made on copper as Cu (I) addition in the perovskite, MAPbI3 through some exotic ways in an intention of Pb replacement, i.e., complete Pb replacement with Cu, which generates MACuxI3 (1 ≤ x ≥ 2); partial lead replacement, i.e., MAPb1−xCuxI3; and cocktail perovskite, i.e., both MAPbI3 and MACuxI3 mixture, and finally they are employed for carbon-based perovskite solar cells. Remarkably, Cu incorporation facilitates the near-infrared (NIR) absorption, indicating a maximum solar spectrum absorbance. Integration of Cu as MAPb1−xCuxI3 results in the maximum PCE of ~12.85%, whereas using 1:1 cocktail perovskite solution of MAPbI3 and MACuxI3 exhibits an average PCE of ~12.43%. On the other hand, during complete Pb substituted perovskites, MACuxI3, the device has only experienced an average PCE of ~4.0%. However, MACuxI3-based PSCs lead to negligible PCE degradation as perceived up to 1000 h, whereas Pb-based other devices are experienced rapid PCE depletion over the same period. Noticeably, Cu-incorporation facilitates a comparatively steeper and lesser PCE degradation rate than Pb-based PSCs. These results may help exploit unlimited possibilities of the potential application of Pb-free based highly stable solar cells and highlights the opportunities for broad solar absorption towards the NIR route and enhanced device stability. Besides, Cu employment has the advantages of environmentally benign impact, earth abundance, good thermal and aqueous stability.

Effect of Cu addition on the microstructure, mechanical properties and degradation rate of Mg-2Gd alloy

The demand for magnesium (Mg) alloy with high elongation, certain strength and good degradation rate used in oil and gas exploitation filed is increasing. Based on Mg-2Gd alloy, effect of copper (Cu) addition (0.25, 0.5 and 0.75 wt.%) on microstructure, mechanical properties and degradation rate were investigated. It showed that more Mg 2 Cu second phases were precipitated and the grain size was refined with increasing Cu content, accompanied with texture changing from < 11 2 ¯ 1 > //ED to < 01 1 ¯ 0 > //ED. As a result, hardness, tensile strength, compressive strength and degradation rate were enhanced while the strain hardening rate and elongation decreased. Nevertheless, the elongation was still up to at least 20%. Overall, the comprehensive mechanical properties and degradation rate of Mg-2Gd alloy can be effectively coordinated by Cu addition.

Brine-Releasable Hydrogen Sulfide in Wine: Mechanism of Release from Copper Complexes and Effects of Glutathione.

Copper-sulfhydryl complexes in wine can be disrupted by addition of brine to release free hydrogen sulfide (H2S), and the resulting "brine-releasable H2S" is reported to correlate with formation of H2S during bottle storage. However, both the mechanism of the brine-release assay and factors affecting the stability of copper sulfhydryls under brine-release conditions are not well understood. By varying brine composition and concentration, it is shown that release of copper-complexed H2S requires the presence of a halide (Cl- and Br-) and is not due to a general "salting-out" effect. Release of copper-complexed H2S by the brine dilution assay is highly temperature-dependent. When H2S and Cu(II) are added to a model wine, brine-releasable H2S decreases markedly (∼10-fold) after a 20 min incubation period prior to performing the brine-release assay. In commercial wines, the fraction of added H2S recovered through the brine-release assay was correlated with the initial glutathione (GSH) concentration (r2 = 0.58) but not with initial Cu. Negligible additional release of H2S from organopolysulfanes was observed following addition of a disulfide-reducing agent (tris(2-carboxyethyl)phosphine). As previous studies have reported a correlation between H2S formed under brine-release conditions and normal storage, these results suggest that the susceptibility of a wine to form latent copper-sulfhydryl precursors of H2S following copper addition is dependent on the concentration of sulfhydryls like GSH.

Effects of Copper Supplementation on Lipid Oxidation and Meat Quality of Merino X Texel Lambs

Two levels of copper sulphate and copper-methionine were evaluated on lipid oxidative stability in liver and Longissimus thoracis (LT) muscle, measured by thiobarbituric acid reactive substances (TBARS) and activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in liver. 40 Merino x Texel lambs were randomly distributed into 5 treatments with 8 animals each. Treatments were: control, without copper addition; 10 or 30 mg of Cu/Kg DM complete diet in the form of Cu-sulphate or Cu-methionine. After 120 days period, animals were slaughtered and samples collected, for analyses on activities of SOD, GPx and TBARS in livers. LT muscle was collected for TBARS analysis at carcass dressing, 3 and 6 days after chilling at 4°C and 12 months after vacuum freezing. SOD and GPx activities were higher in animals receiving copper. TBARS values in muscle were higher in the control group at the time of boning but did not differ after 12 months of vacuum freezing. TBARS values in muscle during shelf life, with a linear increase over the days, did not vary. It was found that copper supplementation, even at considered toxic levels of 30mg/kg DM, plus 9mg/kg basal diet, resulted in increased hepatic concentration of liver antioxidant enzymes and showed no detrimental effects on muscle oxidative stability.