Dynamic multinuclear sites formed by mobilized copper ions in NO x selective catalytic reduction
Abstract not provided
Paolucci, Christopher (ORCID:0000000245069306)↗
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Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada
The restoration of the native form of laccase from B. aclada from the type 2 copper-depleted form of the enzyme was investigated. Copper ions were found to be incorporated into the active site after soaking the depleted enzyme in a Cu{sup +}-containing solution. Laccases belong to the class of multicopper oxidases catalyzing the oxidation of phenols accompanied by the reduction of molecular oxygen to water without the formation of hydrogen peroxide. The activity of laccases depends on the number of Cu atoms per enzyme molecule. The structure of type 2 copper-depleted laccase from Botrytis aclada has been solved previously. With the aim of obtaining the structure of the native form of the enzyme, crystals of the depleted laccase were soaked in Cu{sup +}- and Cu{sup 2+}-containing solutions. Copper ions were found to be incorporated into the active site only when Cu{sup +} was used. A comparative analysis of the native and depleted forms of the enzymes was performed.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Enhancing electrical conductivity and electron field emission properties of ultrananocrystalline diamond films by copper ion implantation and annealing
Copper ion implantation and subsequent annealing at 600 °C achieved high electrical conductivity of 95.0 (Ωcm){sup −1} for ultrananocrystalline diamond (UNCD) films with carrier concentration of 2.8 × 10{sup 18} cm{sup −2} and mobility of 6.8 × 10{sup 2} cm{sup 2}/V s. Transmission electron microscopy examinations reveal that the implanted Cu ions first formed Cu nanoclusters in UNCD films, which induced the formation of nanographitic grain boundary phases during annealing process. From current imaging tunneling spectroscopy and local current-voltage curves of scanning tunneling spectroscopic measurements, it is observed that the electrons are dominantly emitted from the grain boundaries. Consequently, the nanographitic phases presence in the grain boundaries formed conduction channels for efficient electron transport, ensuing in excellent electron field emission (EFE) properties for copper ion implanted/annealed UNCD films with low turn-on field of 4.80 V/μm and high EFE current density of 3.60 mA/cm{sup 2} at an applied field of 8.0 V/μm.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
The structure of plastocyanin tunes the midpoint potential by restricting axial ligation of the reduced copper ion
Blue copper proteins are models for illustrating how proteins tune metal properties. Nevertheless, the mechanisms by which the protein controls the metal site remain to be fully elucidated. A hindrance is that the closed shell Cu(I) site is inaccessible to most spectroscopic analyses. Carbon deuterium (C-D) bonds used as vibrational probes afford nonperturbative, selective characterization of the key cysteine and methionine copper ligands in both redox states. The structural integrity of Nostoc plastocyanin was perturbed by disrupting potential hydrogen bonds between loops of the cupredoxin fold via mutagenesis (S9A, N33A, N34A), variably raising the midpoint potential. The C-D vibrations show little change to suggest substantial alteration to the Cu(II) coordination in the oxidized state or in the Cu(I) interaction with the cysteine ligand. They rather indicate, along with visible and NMR spectroscopy, that the methionine ligand distinctly interacts more strongly with the Cu(I) ion, in line with the increases in midpoint potential. Here we show that the protein structure determines the redox properties by restricting the interaction between the methionine ligand and Cu(I) in the reduced state.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Kinetics of copper ion absorption by cross-linked calcium polyacrylate membranes
The absorption of copper ions from aqueous copper acetate solutions by cross-linked calcium acrylate membranes was found to obey parabolic kinetics similar to that found for oxidation of metals that form protective oxide layers. For pure calcium polyacrylate membranes the rate constant was essentially independent of copper acetate concentration and film thickness. For a cross-linked copolymer film of polyvinyl alcohol and calcium polyacrylate, the rate constant was much greater and dependent on the concentration of copper acetate. The proposed mechanism in each case involves the formation of a copper polyacrylate phase on the surface of the membrane. The diffusion of the copper ion through this phase appears to be the rate controlling step for the copolymer film. The diffusion of the calcium ion is apparently the rate controlling step for the calcium polyacrylate. At low pH, the copper polyacrylate phase consists of the normal copper salt; at higher pH, the phase appears to be the basic copper salt.
Philipp, W. H.↗
Copper ions removal from water using functionalized carbon nanotubes–mullite composite as adsorbent
Highlights: • CNTs–mullite composite was prepared via chemical vapor deposition (CVD) method. • The prepared composite was modified with concentrated nitric acid and chitosan. • The modified CNTs–mullite composites were used as novel adsorbents. • Copper ion removal from water by the prepared adsorbents was performed. • Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. - Abstract: Carbon nanotubes–mullite composite was synthesized by direct growth of carbon nanotubes on mullite particles via chemical vapor deposition method using cyclohexanol and ferrocene as carbon precursor and catalyst, respectively. The carbon nanotubes–mullite composite was oxidized with concentrated nitric acid and functionalized with chitosan and then used as a novel adsorbent for copper ions removal from water. The results demonstrated that modification with concentrated nitric acid and chitosan improves copper ions adsorption capacity of the prepared composite, significantly. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. The carbon nanotubes growth on mullite particles to form the carbon nanotubes–mullite composite with further modification is an inherently safe approach for many promising environmental applications to avoid some concerns regarding environment, health and safety. It was found that the modified carbon nanotubes–mullite composite can be considered as an excellent adsorbent for copper ions removal from water.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
SBA-15 mesoporous silica free-standing thin films containing copper ions bounded via propyl phosphonate units - preparation and characterization
The SBA-15 silica thin films containing copper ions anchored inside channels via propyl phosphonate groups are investigated. Such materials were prepared in the form of thin films, with hexagonally arranged pores, laying rectilinear to the substrate surface. However, in the case of our thin films, their free standing form allowed for additional research possibilities, that are not obtainable for typical thin films on a substrate. The structural properties of the samples were investigated by X-ray reflectometry, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The molecular structure was examined by Raman spectroscopy supported by numerical simulations. Magnetic measurements (SQUID magnetometry and EPR spectroscopy) showed weak antiferromagnetic interactions between active units inside silica channels. Consequently, the pores arrangement was determined and the process of copper ions anchoring by propyl phosphonate groups was verified in unambiguous way. Moreover, the type of interactions between magnetic atoms was determined. - Highlights: • Functionalized free-standing SBA-15 thin films were synthesized for a first time. • Thin films synthesis procedure was described in details. • Structural properties of the films were thoroughly investigated and presented. • Magnetic properties of the novel material was investigated and presented.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
THE EXTREME ULTRAVIOLET SPECTRUM OF HIGHLY CHARGED COPPER IONS
This paper reports the laboratory measurements of extreme ultraviolet spectra of highly charged copper ions. In this work, 82 lines from Cu xv to Cu xxiii in the 160–360 Å wavelength range are identified as the transitions of the 2p{sup 2}3p–2p{sup 2}3d, 2p{sup 4}3s–2p{sup 4}3p, 2p{sup 4}3p–2p{sup 4}3d, 2p{sup 5}3s–2p{sup 5}3p, 2p{sup 5}3s–2p{sup 5}3p, 3s3p–3p{sup 2}, 3s{sup 2}3p{sup 3}-3s3p{sup 4}, 3s{sup 2}3p–3s3p{sup 2}, 3s{sup 2}3p{sup 3}–3s3p{sup 4}, and 2p{sup 4} ({sup 3}P)3s–2p{sup 4} ({sup 3}P) 3p, in which 40 spectral lines have been newly and accurately measured. Their identification is based on comparisons with available experimental and theoretical values and the calculations with Cowan codes.
74 ATOMIC AND MOLECULAR PHYSICS↗
Development of a New 4-Amino-1,8-Naphthalimide Derivative as a Fluorescent Probe for Monitoring the Divalent Copper Ion
This article presents the design and synthesis of a new variant of the 4-amino-1,8-naphthalimide fluorescent probe for monitoring the divalent copper ion, Cu{sup 2+}. The probe BRST, functionalized with two propionic carboxylic acid groups in its receptor moiety, demonstrated high selectivity and sensitivity for the detection of Cu{sup 2+} in competitive media of various metal ions in DMSO/HEPES buffer solution (1:1; pH 7.4), with a fluorescence quenching of 75.41%. Besides its good linearity with Cu{sup 2+}, the probe yielded commendable values of the association constant and the detection limit, 5.54 × 10{sup 5} M{sup –1} and 4.33 × 10{sup –9} M, respectively. The quenching of the fluorescence intensity of the sensor in the presence of Cu{sup 2+} ions is attributable to the strong paramagnetic nature of the Cu{sup 2+} ion. The fluorescence 'turn off' behavior of this simple and effective probe was successfully applied for the determination of Cu{sup 2+} levels in untreated water samples, with excellent recovery rates of 98–105.8%.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Chitosan Functionalization with Amino Acids Yields to Higher Copper Ions Adsorption Capacity
Chitosan (Chi) beads were conjugated with three different amino acids [namely, glutamic acid (GLU), methionine (MET), and taurine (TAU)] aiming to increase the divalent copper ions uptake in aqueous media. Scanning Electron Microscopy evidenced the development of a large porous structure after amino acid functionalization, associated with the increase in a number of amino groups in the polymer backbone. X-Ray Photoelectron Spectroscopy and Fourier-Transform Infrared Spectra analyses were also employed to assess the conjugation of these three different amino acids in chitosan backbone. Adsorption experiments were conducted in a batch process, at 298 K, and kinetic data indicated a slightly better fitting for the pseudo-first-order model when compared to pseudo-second order. Intraparticle diffusion model suggested a three-step mechanism for Cu(II) adsorption kinetics, limited by the third step, the intraparticle diffusion. The isotherm data fitting to the traditional Langmuir and Freundlich models indicated a better fit for the former case. The amino acid conjugation resulted in the increase of the maximum adsorption capacity for Cu(II) from 1.30 mmol g{sup −1} prior to amino acid conjugation to values as high as 2.31 mmol g{sup −1}, 2.40 mmol g{sup −1} and 2.68 mmol g{sup −1} for Chi–TAU, Chi–GLU, and Chi–MET, respectively. These results are attributed to the introduction of additional amino groups and new carboxylate and amino acid residues into the chitosan backbone, which might also be explored for amino acid demanding applications.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Copper ions suppress abscisic acid biosynthesis to enhance defence against Phytophthora infestans in potato
Abstract Copper‐based antimicrobial compounds are widely and historically used to control plant diseases, such as late blight caused by Phytophthora infestans , which seriously affects the yield and quality of potato. We previously identified that copper ion (Cu 2+ ) acts as an extremely sensitive elicitor to induce ethylene (ET)‐dependent immunity in Arabidopsis . Here, we found that Cu 2+ induces the defence response to P. infestans in potato. Cu 2+ suppresses the transcription of the abscisic acid (ABA) biosynthetic genes StABA1 and StNCED1 , resulting in decreased ABA content. Treatment with ABA or inhibitor fluridone made potato more susceptible or resistance to late blight, respectively. In addition, potato with knockdown of StABA1 or StNCED1 showed greater resistance to late blight, suggesting that ABA negatively regulates potato resistance to P. infestans . Cu 2+ also promotes the rapid biosynthesis of ET. Potato plants treated with 1‐aminocyclopropane‐1‐carboxylate showed enhanced resistance to late blight. Repressed expression of StEIN2 or StEIN3 resulted in enhanced transcription of StABA1 and StNCED1 , accumulation of ABA and susceptibility to P. infestans . Consistently, StEIN3 directly binds to the promoter regions of StABA1 and StNCED1 . Overall, we concluded that Cu 2+ triggers the defence response to potato late blight by activating ET biosynthesis to inhibit the biosynthesis of ABA.
Liu, Hai‐Feng↗
Removal of Iron and Copper Ions from the Liquid Phase by Modified Polymeric Membranes
Preparation of polymeric membranes based on cellulose acetate and modified by adding different amounts of a pore generating agent, which was polyvinylpyrrolidone (PVP), is presented and potential application of the membranes obtained for the removal of iron and copper ions from liquid phase is examined. Addition of various amounts of PVP has an impact on the physical (porosity, equilibrium water content and permeability) and chemical (content of the surface oxygen group, pH) properties of the membranes obtained. Filtration of iron and cupper solution leads to significant changes in the total content of surface oxygen groups, however the acidic oxygen groups remain dominant. With the content of PVP increasing within a certain range, the membrane permeability is improved. The membranes obtained show higher efficiency in removal of Fe{sup 3+} than Cu{sup 2+} ions, but with increasing content of PVP the efficiency in iron ions removal decreases and the total filtration resistance decreases after filtration of iron ions solutions.
36 MATERIALS SCIENCE↗
Electrochemical Behavior of Copper Ion Complexed with Nanoparticle Organic Hybrid Materials
Nanoscale Organic Hybrid Materials (NOHMs) have unique properties that show potential for their use as novel electrolytes that can interact with redox active species. In this work, we probe the effects of adding poly(ethyleneimine)-based NOHMs (NOHM-I-PEI) on copper ion electrochemical reactions. As NOHM-I-PEI is added to a solution containing Cu(II), the voltammetric peak current decreases. This is likely caused by strong complex formation between the PEI nitrogen and the copper, similar to complexation observed in solutions of the polymer with copper. Upon copper addition to a NOHM-I-PEI solution, the pH decreases from 10.1, plateauing at pH = 5.3 at ~3:1 N:Cu ratio indicating that Cu(II) displaces protons. The UV–visible spectra exhibit a Cu-PEI peak, the intensity of which levels off at ~2.8 N:Cu. Acid titration of the N-moieties of the PEI reveals three inflections corresponding to N-environments in the PEI. Upon controlling the pH of the solution by buffering, the "sequestration" of Cu(II) is found to occur when there are unprotonated nitrogens present in the NOHM-I-PEI system; this phenomenon is also supported by UV-vis results. Furthermore, this work highlights the potential of and the design of NOHMs to carry charged electroactive species in solutions along with key factors to control for optimal function.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Ionization injection of highly-charged copper ions for laser driven acceleration from ultra-thin foils
Laser-driven ion acceleration is often analyzed assuming that ionization reaches a steady state early in the interaction of the laser pulse with the target. This assumption breaks down for materials of high atomic number for which the ionization occurs concurrently with the acceleration process. Using particle-in-cell simulations, we have examined acceleration and simultaneous field ionization of copper ions in ultra-thin targets (20-150 nm thick) irradiated by a laser pulse with intensity 1 × 10 21 W/cm 2 . At this intensity, the laser pulse drives strong electric fields at the rear side of the target that can ionize Cu to charge states with valence L-shell or full K-shell. The highly-charged ions are produced only in a very localized region due to a significant gap between the M- and L-shells' ionization potentials and can be accelerated by strong, forward-directed sections of the field. Such an "ionization injection" leads to well-pronounced bunches of energetic, highly-charged ions. We also find that for the thinnest target (20 nm) a push by the laser further increases the ion energy gain. Thus, the field ionization, concurrent with the acceleration, offers a promising mechanism for the production of energetic, high-charge ion bunches.
43 PARTICLE ACCELERATORS↗
Ligand-Capped CdTe Quantum Dots as a Fluorescent Nanosensor for Detection of Copper Ions in Environmental Water Sample
In this work, as a novel fluorescent nano-sensor, a ligand-capped CdTe QDs (CdTe-L QDs) was designed for the detection and quantification of Cu{sup 2+} ions in environmental water samples. The synthesized QDs were characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FTIR), UV–Vis spectrophotometry and fluorescence spectroscopy. Optical properties of the produced nanosensor were monitored by UV–Vis and fluorescence spectrophotometry. It was observed that fluorescence intensity of the produced nano-sensor selectively quenched by adding Cu{sup 2+} ions in comparison to other metal ions tested. Using CdTe-L QDs, a rapid and facile analytical method was developed to determine Cu{sup 2+} ions in the concentration range of 5.16 ± 0.07 × 10{sup − 8} mol L{sup − 1}–1.50 ± 0.03 × 10{sup − 5} mol L{sup − 1} with a detection limit of 1.55 ± 0.05 × 10{sup − 8} mol L{sup − 1}. The nanosensor was successfully applied for the determination of Cu{sup 2+} ions in various water samples, and the results were compared with the standard method. .
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Irradiation route to aqueous synthesis of highly luminescent ZnSe quantum dots and its function as a copper ion fluorescence sensor
Highlights: • Radiation chemical technique can provide a useful route for synthesis of ZnSe QDs. • Chelating nature of ethylene diamine is exploited for capping nanoparticles. • ZnSe QDs can be a suitable sensitive alternative to toxic cadmium-based system. • Cu(II) ion is probed by QDs in the presence of other physiologically relevant ions. - Abstract: Size-controlled synthesis of stable ZnSe QDs with narrow distribution in aqueous environment through conventional soft chemical method still poses a challenge. The proposed radiation assisted strategy demonstrates aqueous synthesis of stable, monodisperse and luminescent ZnSe QDs capped with chelating ethylene diamine under ambient conditions and at room temperature. Radiation chemical method facilitates in slow and in-situ release of selenium ion from sodium selenosulfate. The concentrations of precursors, such as zinc salt, selenium source, ethylene diamine and absorbed radiation (7–90 kGy) dose were optimized for obtaining good quality particles. Selective quenching of luminescence of as-synthesized quantum dots (QDs) by Cu{sup 2+} ions vis-à-vis other physiologically important cations provide evidence for use of ZnSe quantum dots as alternative to toxic Cd-based quantum dots to probe Cu{sup 2+} ions. The linear relation of ratio of loss in emission intensity as a function of concentration of Cu(II) indicates detection limit in nano-molar range.
36 MATERIALS SCIENCE↗
Photoactivation and relaxation studies on the cyanobacterial orange carotenoid protein in the presence of copper ion
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solar (fuels), photosynthesis (natural and artific↗
Structural Studies of the Alzheimer's Amyloid Precursor Protein Copper-binding Domain Reveal How it Binds Copper Ions
Abstract not provided
Kong, Geoffrey K.-W.↗