Reduction Of Cu Research Articles

Thermal Annealing of Polycatecholamine Coated Carbon Nanotube: A New Path for Copper-Carbon Nanotube Composites Fabrication

In present days, the continuous miniaturization of electronic devices comes along with a problematic reduction of their life-time. This is due to the underlying current density being operated increasingly close to the maximum current-carrying capacity (ampacity) of the materials (copper, gold...) used in the conduction channels of micro-circuitry. In this respect, there is a growing attention for new materials with higher ampacity, and copper-carbon nanotube (CNT) composites could constitute a promising alternative. The interest of such copper-carbon composites relies on the combination of the complementary properties of both materials: the high conductivity of copper and the high ampacity of CNT.However, the fabrication of an efficient Cu-CNT composite still remains a huge challenge and, up to now, the metal filling of a CNT hydrophobic matrix using electrochemical methods systematically requires an organic solvent based solution, which is not industrially and ecologically friendly. This constitutes an important drawback of those types of fabrication paths.A new promising way to fabricate such a composite by electrochemistry is shown in our work (see figure 1). It is based on a copper doped polycatecholamine coating of CNT. The coated CNT are deposited to form a matrix and the interstices between CNT are then filled with metallic copper by using an electrochemical step in aqueous solution.In this context, it is relevant to study how the coating impacts the CNT surface conductivity. In this respect, we characterize the CNT coating resistance before and after thermal annealing using C-AFM. Combined SEM and STEM images show the apparition of well dispersed nanoparticles on the CNT surface after thermal annealing. The change of nuclei density and their size distribution is also characterized in function of the annealing temperature. Finally, we use XPS and DSC to show that annealing of copper doped polycatecholamine coated CNT is, in fact, able to promote the reduction of Cu(II) into Cu(I) and Cu(0). Figure 1

Effect of zeolite topology on NH3-SCR activity and stability of Cu-exchanged zeolites

The catalytic activity and stability of Cu-exchanged zeolites Cu-ZSM-5 (MFI topology), Cu-TNU-9 (TUN), Cu-FER (FER) and steamed Cu-Y (FAU) were evaluated in the selective catalytic NO reduction by ammonia (NH3-SCR). The NH3-SCR activity of the investigated catalysts strongly depended on the feed composition, i.e., the presence of H2O (5.0 Vol.-% of H2O). The catalysts revealed high stability during 24 h of NH3-SCR reaction, also in the presence of water vapour. DR UV–vis and FT-IR with probe molecules (CO or NO) showed the presence of isolated Cu+/Cu2+ and aggregated copper oxide species. Although Cu-ZSM-5 is less active than Cu-TNU-9 in catalysing NO oxidation to NO2, both catalysts revealed similar activity in the NH3-SCR reaction. Applying Rapid-Scan FT-IR spectroscopy and 2D COS analysis the reaction mechanism of NH3-SCR on Cu-exchanged zeolites was investigated. It is proposed that NH3-SCR over the studied Cu-exchanged catalysts proceeds via [Cu(OH)(NH3)2(NO)]+ intermediates followed by the reduction of Cu(II) to Cu(I). The differentiated speciation of copper sites is reflected in their various susceptibility for the reduction and finally affects the catalytic activity and stability of the zeolitic catalysts. The formation of the [Cu(OH)(NH3)2(NO)]+ mixed ligand species is governed by the competition between the O2− and NH3 ligands. Also the stability of the forms initiating NH3-SCR, i.e., [Cu(NH3)4]2+, [Cu(OH)(NH3)3]+ and [Cu(NH3)2]+, is ruled by the confine interaction of ammonia molecules, which can be both adsorbed on a protonic site and ligated to copper sites with the framework oxygen atoms.

Mechanistic analysis of the cathodic stripping square-wave voltammetric response of the copper‑arsenic system at a mercury electrode

Despite arsenite can be reduced to As(0) and deposited at the surface of solid electrodes such as gold, platinum, or copper, it cannot form amalgams with mercury, and so the addition of other metal ions is required for its deposition. In this manuscript, mechanistic analysis of the cathodic stripping square-wave voltammetric response of the system copper‑arsenic is presented. For the analysis of experimental responses, a mathematical model is used to consider that a surface-active reagent undergoes a charge transfer step followed by a chemical reaction. The dependences of the differential peak current, and the respective peak potential and half-peak width on the square-wave frequency were used to estimate the apparent stability constant of arsenide formation and that the electrode reaction would involve the direct transfer of 2 electrons, while the simulation and fit of forward and backward voltammetric responses have been useful for inferring other parameters such as the formal charge transfer rate constant of the global electron transfer reaction, a pseudo-first order homogeneous rate constant associated with arsenide formation, and the charge transfer coefficient of the global electron transfer reaction. Besides the values estimated for each of those parameters, all simulations indicate that the reduction of copper instead of arsenic would be taking place during the cathodic stripping scan. Accordingly, the trace-analysis reaction of arsenic in the presence of copper would be based on the surface accumulation of a metal complex, where Cu 2+ would be the metal cation and an arsenide species the ligand. The stability of that complex at the surface of a mercury electrode would depend not only on the applied potential, but also on the ratio between copper, arsenic, and protons. • Mechanistic analysis of the CS-SWV response of the system copper-arsenic is presented. • This is the first time that a mathematical model of such complexity is used for simulating experimental voltammograms. • The simulation and fit of the experimental curves are step-by-step described. • Simulations indicate that the reduction of Cu(II) instead of As(0) takes place during the cathodic stripping scan. • A surface analysis is required when the scan-rate affect the apparent reversibility of more than one kinetic constant.

Effect of the kind of cupric compound deposit on thermal decomposition of anion exchangers

The effect of the inorganic deposit on the thermal decomposition of hybrid ion exchangers (HIXs) has not been comprehensively studied before. Therefore, as part of this research anion exchangers containing cupric compound in their matrix (CuO, Cu(OH)2 and Cu4(OH)6SO4) were subjected to thermal analysis. Strongly basic commercial anion exchangers, i.e. a macroreticular anion exchanger (M) and a gel-like anion exchanger (G), were used as the host materials. M, M/CuO, M/Cu(OH)2 and G, G/CuO, G/Cu4(OH)6SO4 were subjected to thermal analysis under respectively air and N2. The samples of the HIXs contained 57.8–84.5 mg Cu/g. The results of twelve experiments are discussed on the basis of the TG/DTG curves and XRD patterns for the solid residues. The effects of: (a) the process conditions, (b) the type of deposit and (c) the structure of the anion exchanger on the course of the thermal transformations, the process end temperature, the amount of carbonizate in the post-pyrolysis residue and the composition of the inorganic phase (CuO after combustion, Cu0 or Cu2S after pyrolysis) were determined. It was demonstrated that during the thermal decomposition of the HIXs under N2 the reduction of Cu(II) was taking place, and owing to this hydrogen-consuming conversion more carbonizate formed than in the pyrolysis of the pure resins, as under hydrogen deficit the hydrocarbon radicals condensed into large non-volatile particles.

New Insights into The Photoactivity of Shape-Tailored BiVO4 Semiconductors via Photocatalytic Degradation Reactions and Classical Reduction Processes.

In the present study, additive-free, pH-driven, hydrothermal crystallization was used to obtain shape-tailored monoclinic BiVO4 photocatalysts. The as-prepared BiVO4 products were systematically characterized, uncovering their crystallographic, morphologic and optical properties, while their applicability was verified in the visible light-driven photodegradation of oxalic acid and rhodamine B. Monoclinic clinobisvanite was obtained in most cases, with their band gap values located between 2.1 and 2.4 eV. The morphology varied from large, aggregated crystals, individual microcrystals to hierarchical microstructures. It was found that the degradation efficiency values obtained in the case of oxalic acid were directly related to the presence of (040) crystallographic plane, while the degradation of rhodamine B was partially independent by the presence of this structural feature. The importance of (040) crystallographic plane was also demonstrated via the reduction of Cu2+ to Cu, by analyzing the Raman spectra of the Cu containing samples, the mean primary crystallite size of Cu and Cu content. Furthermore, the presence of (040) crystallographic plane was directly proportional with the hydrodynamic properties of the powders as well.

Mechanisms of detoxification of high copper concentrations by the microalga Chlorella sorokiniana.

Microalgae have evolved mechanisms to respond to changes in copper ion availability, which are very important for normal cellular function, to tolerate metal pollution of aquatic ecosystems, and for modulation of copper bioavailability and toxicity to other organisms. Knowledge and application of these mechanisms will benefit the use of microalgae in wastewater processing and biomass production, and the use of copper compounds in the suppression of harmful algal blooms. Here, using electron microscopy, synchrotron radiation-based Fourier transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, and X-ray absorption fine structure spectroscopy, we show that the microalga Chlorella sorokiniana responds promptly to Cu2+ at high non-toxic concentration, by mucilage release, alterations in the architecture of the outer cell wall layer and lipid structures, and polyphosphate accumulation within mucilage matrix. The main route of copper detoxification is by Cu2+ coordination to polyphosphates in penta-coordinated geometry. The sequestrated Cu2+ was accessible and could be released by extracellular chelating agents. Finally, the reduction in Cu2+ to Cu1+ appears also to take place. These findings reveal the biochemical basis of the capacity of microalgae to adapt to high external copper concentrations and to serve as both, sinks and pools of environmental copper.

54P The combination of copper oxide nanoparticles and N-acetyl-L-cysteine triggers rapid oxidative burst and death of wild-type and multidrug-resistant tumour cells

Overcoming drug resistance is a major problem in cancer therapy. Tumor cells are vulnerable to reactive oxygen species (ROS). The oxygen burst can be evoked by metal oxide nanoparticles (NPs) alone and/or together with conventional or novel compounds. We investigated the antitumor potential of the combination of copper oxide NPs and N-acetyl-L-cysteine (NAC) against various human tumor cell lines. CuO NPs (80±20 nm as determined by dynamic light scattering) were synthesized by the precipitation method. Intracellular accumulation of CuO NPs was measured by atomic absorption spectroscopy. The panel of cell lines included HCT116 colon and MDA-MB-231 triple-negative breast carcinomas as well as K562 (CML) cell line and its multidrug-resistant K562/4 subline. The cytotoxicity of CuO NPs, NAC and their combination were determined in MTT assays. Flow cytometry was used to analyze the mechanisms of cell response. Caspase-3 and poly(ADPribose) polymerase (PARP) were detected by immunoblotting. CuO NPs showed a slight toxicity for all tested cell lines after 72 h, while in combination with the non-toxic NAC a rapid (within 2 h) ROS generation and cell death by 8 h were detected. CuO NPs weakly accumulated in the cells, so ROS generation is likely to occur mainly outside the cells. The IC50 of the combination was 2-3 orders of magnitude smaller compared to NPs alone. Death associated events differed between the cell lines but generally caspase-independent apoptosis was followed by irreversible damage of the plasma membrane. Importantly, the combination of CuO NPs with NAC was equally potent for K562 cells and the multidrug-resistant K562/4 subline. Reduction of Cu2+ to Cu+ upon interaction with the thiol group in NAC can trigger ROS formation. The combination of CuO NPs and NAC killed human tumor cell lines including the multidrug-resistant variant. Rapid ROS generation can be promising in situations where tumor cells acquire multidrug resistance during treatment. Also, engineering of supramolecular systems will allow to guide copper to critical cysteine residues in specific proteins for their oxidative destruction.

The influence of sex and strain on trace element dysregulation in the brain due to diet-induced obesity

BackgroundThe objective of this study was to identify interaction effects between diet, sex, and strain on trace element dysregulation and gene expression alterations due to diet-induced obesity (DIO) in the hippocampus, striatum, and midbrain. MethodsMale and female C57BL/6 J (B6 J) and DBA/2 J (D2 J) mice were fed either a low fat (10 % kcal) diet (LFD) or high fat (60 % kcal) diet (HFD) for 16 weeks, then assessed for trace element concentrations and gene expression patterns in the brain. ResultsIn the hippocampus, zinc was significantly increased by 48 % in D2 J males but decreased by 44 % in D2 J females, and divalent metal transporter 1 was substantially upregulated in B6 J males due to DIO. In the striatum, iron was significantly elevated in B6 J female mice, and ceruloplasmin was significantly upregulated in D2 J female mice due to DIO. In the midbrain, D2 J males fed a HFD had a 48 % reduction in Cu compared to the LFD group, and D2 J females had a 37 % reduction in Cu compared to the control group. ConclusionsThe alteration of trace element homeostasis and gene expression due to DIO was brain-region dependent and was highly influenced by sex and strain. A significant three-way interaction between diet, sex, and strain was discovered for zinc in the hippocampus (for mice fed a HFD, zinc increased in male D2 Js, decreased in female D2 Js, and had no effect in B6 J mice). A significant diet by sex interaction was observed for iron in the striatum (iron increased only in female mice fed a HFD). A main effect of decreased copper in the midbrain was found for the D2 J strain fed a HFD. These results emphasize the importance of considering sex and genetics as biological factors when investigating potential associations between DIO and neurodegenerative disease.

Triapine Derivatives Act as Copper Delivery Vehicles to Induce Deadly Metal Overload in Cancer Cells

Thiosemicarbazones continue to attract the interest of researchers as potential anticancer drugs. For example, 3-aminopyridine-2-carboxaldehyde thiosemicarbazone, or triapine, is the most well-known representative of this class of compounds that has entered multiple phase I and II clinical trials. Two new triapine derivatives HL1 and HL2 were prepared by condensation reactions of 2-pyridinamidrazone and S-methylisothiosemicarbazidium chloride with 3-N-(tert-butyloxycarbonyl) amino-pyridine-2-carboxaldehyde, followed by a Boc-deprotection procedure. Subsequent reaction of HL1 and HL2 with CuCl2·2H2O in 1:1 molar ratio in methanol produced the complexes [CuII(HL1)Cl2]·H2O (1·H2O) and [CuII(HL2)Cl2] (2). The reaction of HL2 with Fe(NO3)3∙9H2O in 2:1 molar ratio in the presence of triethylamine afforded the complex [FeIII(L2)2]NO3∙0.75H2O (3∙0.75H2O), in which the isothiosemicarbazone acts as a tridentate monoanionic ligand. The crystal structures of HL1, HL2 and metal complexes 1 and 2 were determined by single crystal X-ray diffraction. The UV-Vis and EPR spectroelectrochemical measurements revealed that complexes 1 and 2 underwent irreversible reduction of Cu(II) with subsequent ligand release, while 3 showed an almost reversible electrochemical reduction in dimethyl sulfoxide (DMSO). Aqueous solution behaviour of HL1 and 1, as well as of HL2 and its complex 2, was monitored as well. Complexes 1−3 were tested against ovarian carcinoma cells, as well as noncancerous embryonic kidney cells, in comparison to respective free ligands, triapine and cisplatin. While the free ligands HL1 and HL2 were devoid of antiproliferative activity, their respective metal complexes showed remarkable antiproliferative activity in a micromolar concentration range. The activity was not related to the inhibition of ribonucleotide reductase (RNR) R2 protein, but rather to cancer cell homeostasis disturbance—leading to the disruption of cancer cell signalling.

Comparative Study of the Effect of Water on Cu/SiO2 Catalysts Prepared by Different Methods: Structure, Hydrogenation Performance and the Promotion of Reduction Cu+ to Cu0

AbstractThe effect of water on the performance of Cu/SiO2 catalysts prepared by four different methods was investigated by ethyl acetate (AcOEt) hydrogenation to ethanol (EtOH). The catalysts were characterized using XRD, FT‐IR, TPR, N2O titration, TEM and XPS to understand the structure‐catalytic efficiency relationships. The results showed high copper species dispersion and strong interaction between copper and silica were responsible for water‐tolerant hydrogenation performance of catalysts. Interestingly, although water oxidized slightly Cu0 or Cu+ to Cu2+ in the reaction, it maybe promote the reduction of Cu+ to Cu0. Notably, the Cu+ content of spent catalysts at condition with water decreased in comparison with that of spent catalysts at condition without water. This might be because that water formed film on Cu2O surface by adsorbing, which enhanced the spillover of dissociated H from Cu0 to Cu+ sites and then promoted its reduction.

Blocking Ion Migration Stabilizes the High Thermoelectric Performance in Cu2 Se Composites.

The applications of mixed ionic-electronic conductors are limited due to phase instability under a high direct current and large temperature difference. Here, it is shown that Cu2 Se is stabilized through regulating the behaviors of Cu+ ions and electrons in a Schottky heterojunction between the Cu2 Se host matrix and in-situ-formed BiCuSeO nanoparticles. The accumulation of Cu+ ions via an ionic capacitive effect at the Schottky junction under the direct current modifies the space-charge distribution in the electric double layer, which blocks the long-range migration of Cu+ and produces a drastic reduction of Cu+ ion migration by nearly two orders of magnitude. Moreover, this heterojunction impedes electrons transferring from BiCuSeO to Cu2 Se, obstructing the reduction reaction of Cu+ into Cu metal at the interface and hence stabilizes the β-Cu2 Se phase. Furthermore, incorporation of BiCuSeO in Cu2 Se optimizes the carrier concentration and intensifies phonon scattering, contributing to the peak figure of merit ZT value of ≈2.7at 973 K and high average ZT value of ≈1.5 between 400 and 973 K for the Cu2 Se/BiCuSeO composites. This discovery provides a new avenue for stabilizing mixed ionic-electronic conduction thermoelectrics, and gives fresh insights into controlling ion migration in these ionic-transport-dominated materials.

Metamaterials Based on Polyvinyl Alcohol with Metal or Metal Oxide Particles: Synthesis and Study by Nondestructive Physical Methods

Methods for the synthesis of polymer hydrogel–metal metamaterials based on polyvinyl alcohol and reduced Cu, Ag, Co, and Fe (or magnetite Fe3O4) particles, including the stage of chemical or thermal reduction or chemical precipitation were proposed. The effect of the synthesis conditions on the size of metal or oxide particles and the regularity of particle distribution in the polymer was studied. The samples of composite materials synthesized under different conditions were characterized by nondestructive X-ray fluorescence and X-ray diffraction methods. An XRD study revealed that after the thermal reduction of Cu, Co, and Fe, the composite contained a significant amount of metal oxides. The optimum conditions for the synthesis of polyvinyl alcohol–magnetite metamaterials were found.

In situ/operando spectroscopic studies on NH3–SCR reactions catalyzed by a phosphorus-modified Cu-CHA zeolite

The modification of Cu-exchanged zeolites with phosphorus represents a promising method to enhance their hydrothermal stability, which is of pivotal importance for catalysts that promote the selective catalytic reduction of NO with ammonia (NH3–SCR). In this study, we investigated the reaction mechanism of NH3–SCR catalyzed by a phosphorus-modified CHA zeolite that contains active Cu species (Cu-P-CHA), and assessed the effect of the phosphorus modification on the hydrothermal stability of the catalyst by employing in situ/operando spectroscopic methods. In their entirety, the combined results from in situ/operando IR, UV–vis, and XANES experiments revealed that the NH3–SCR process over Cu-P-CHA proceeds via the reduction of Cu(II) to Cu(I) followed by a reoxidation of Cu(I) to Cu(II). In addition, we found that the phosphorus modification improved the hydrothermal durability of the catalyst by retaining a higher amount of the redox-active Cu species and the zeolite framework.

Natural polyphenols enhanced the Cu(II)/peroxymonosulfate (PMS) oxidation: The contribution of Cu(III) and HO•

Copper ion (Cu(II)) in water or wastewater has been reported to trigger peroxymonosulfate (PMS) oxidation of organic contaminants (OCs). However, this process can only work in alkaline condition, which limits its potential application. In this study, we found that the introduction of natural polyphenols in the Cu(II)/PMS process can significantly promote the degradation of tetrabromobisphenol A (TBBPA), one of the most widely used brominated flame retardants, in the pH range of 4.3−9.0. With gallic acid (GA) as a representative natural polyphenol, the degradation of TBBPA by GA/Cu(II)/PMS process reached 84.6% in 10 min at initial pH of 4.3 (without pH adjustment), which was 2.2 times higher than that by Cu(II)/PMS process. Multiple reactive oxidants, including Cu(III), hydroxyl radical (HO•) and singlet oxygen, were generated in this process among which Cu(III) and HO• contributed to TBBPA degradation with Cu(III) playing the dominant role. GA accelerated the reduction of Cu(II) to Cu(I) due to the strong chelation and electron-donating capacity of ortho-hydroxyl groups in GA, and then Cu(I) was quickly oxidized by PMS to Cu(III) which can be further acid-catalyzed to produce HO•. TBBPA transformation mainly proceeded through electron abstraction, oxidative debromination and ring-opening reaction pathways. The feasibility of in-situ utilizing natural organic matter (NOM, enriched with polyphenol moieties) to accelerate the degradation of TBBPA by Cu(II)/PMS process in surface water and wastewater was confirmed. The findings of this study indicate that the coupling of NOM and Cu(II), which are present in contaminated water or wastewater, can potentially improve PMS oxidation of OCs in a wide range of pH.

Nano-size bimetallic ternary hydrogenation catalysts based on nickel and copper complexes

The turnover frequencies of multicomponent ternary catalytic systems formed on the basis of Ni(acac)2 and Cu(acac)2 with LiAlH4 at Т = 30 оС and РН2 = 2 atm in styrene hydrogenation were determined. It was shown that, at other things being equal, catalytic activity is defined by the order of mixing of the components at the catalyst formation stage. Namely, three particular cases are considered: sequential reduction of Ni(acac)2 and Cu(acac)2 by LiAlH4 (first Ni(acac)2, then Cu(acac)2 and vice versa) and simultaneous reduction of Ni(acac)2 and Cu(acac)2 with LiAlH4. It has been established that nano-sized structures of the core@shell type act as carriers of catalytic activity. The nano-sized structures are stabilized by the ligand shell, which contain Li(acac) as well as AlH4– and AlH63–-anions. The model of the catalytically active (in styrene hydrogenation) nanoparticle formed by sequential reduction of Cu(acac)2 with LiAlH4 and Ni(acac)2 is presented.

A novel digital image method for determination of reducing sugars in aged and non-aged cachaças employing a smartphone

For the first time, a method is proposed for colorimetric determination of reducing sugars in cachaça employing digital image and a smartphone as detector. The method was based on the reduction of Cu(II) to Cu(I) by sugars and followed by the formation of a colored Cu(I)-Neocuproine complex. A calibration curve was linear from 0.1 to 15 g L−1 for glucose and fructose with limits of detection of 0.012 g L−1 and 0.010 g L−1, respectively. It was observed that the non-aged cachaças, known for having inferior flavors and aromas, had a reducing sugar content three times higher than the aged cachaças, once a common practice among producers is to add sugar to adjust sensory deficits in the final product. Furthermore, the method is simple, does not require complex technical knowledge and it could be used as a tool to check possible fraud, adulteration or non-compliance to the law.

A novel approach to prepare Cu(I)Zn@MIL-100(Fe) adsorbent with high CO adsorption capacity, CO/CO2 selectivity and stability via controlled host–guest redox reaction

The development of a CO-selective adsorbent with large CO adsorption capacity, high CO/CO2 selectivity, and good stability is an industrial challenge. In this study, a novel Cu(I)-incorporated MIL-100(Fe) adsorbent for CO/CO2 separation is prepared using a host–guest redox strategy by exploiting the co-addition of Zn(II) and Cu(II). The addition of Zn(II) resulted in a higher Cu(I) yield of the adsorbent due to the facilitated regeneration of Fe(II), which was utilized for the reduction of Cu(II). Remarkably, the CO/CO2 selectivity (104) of Cu(I)Zn@MIL-100(Fe)-10 was considerably higher than that of the benchmark Cu(I)-incorporated adsorbents. Increasing the Zn(II) concentration in Cu(I)Zn@MIL-100(Fe)-10 improved the oxygen resistance. Density functional theory calculations support our hypothesis that the above improvements are derived from stronger σ-bonding between Cu(I) and CO and the facilitation of Fe(II) regeneration by the addition of Zn(II). This study opens a new perspective for developing efficient CO-selective π-complexation adsorbents with high CO/CO2 selectivity and superior oxygen resistance.

ASYMMETRIC WETTED SECTOR ANGLE IN WATER DISTRIBUTION OF TRAVELING GUN IRRIGATION SYSTEMS

ABSTRACT This work aimed to simulate the water distribution of traveler gun irrigation, working with asymmetrical wetted angles and in windy conditions. In the simulations of a sprinkler with uniform radial profile, the following were considered: i) wetted angles between 180 and 330°; ii) wetted angle asymmetries from 0 to 90°; iii) wind speeds from 0 to 4.5 m s-1; and iv) wind direction of 0, 45, and 90°. Christiansen uniformity coefficients (CU) were calculated for strip widths from 30 to 100% of the sprinkler wetted diameter (WD). Regardless of the wetted angle adjustment, irrigations under wind speeds of 4.5 m s-1 should be avoided and strip spacings of less than 50% WD provide high CU for wind speeds up to 3.0 m s-1. For any wind conditions, asymmetries in the wetted angle led to a reduction in CU for a wetted angle of 210°. In the range of wetted angle from 270 to 330°, asymmetric adjustments of up to 20° provided a higher CU than 80% for a wind speed of 3 m s-1 and directions diagonal and perpendicular to the travel path associated with strip spacings between 60 to 70% WD, which are the spacings recommended by manufacturers of traveler irrigation machines.

Synthesis of Spherical Copper Microparticles by Reduction of Cu(II) Ions with Benzyl Alcohol in the Presence of 2-[2-(2-Methoxyethoxy)etoxy]acetic Acid

Spherical copper microparticles were synthesized by reduction of Cu2+ ions with benzyl alcohol in the presence of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid at 195°C. The resulting particles were characterized by X-ray phase analysis and electron microscopy. The influence of the synthesis conditions (synthesis temperature and time, as well as stabilizer, copper ions, and sodium hydroxide concentrations) on the size, morphology, and degree of polydispersity of the resulting copper particles was assessed.

Surfactant assisted one-pot synthesis of copper nanoparticle arrays and their hydrogenation efficiency

Abstract Copper nanoparticle arrays were synthesized by the aqueous phase chemical reduction of Cu2+ to Cu0 using glucose as an environmentally benign reducing agent. The UV absorption spectrum exh...