Response Of Cu Research Articles

Ultrafast third-order nonlinear optical response of Cu:Bi 2O 3 nanocomposite films

Ultrafast third-order nonlinear optical responses of the as-deposited and annealed Cu:Bi 2O 3 nanocomposite films were investigated by using femtosecond Z-scan and time-resolved optical Kerr effect (OKE) techniques at the wavelength of 800 nm. The Z-scan measurement showed that both the real and imaginary parts of the third-order nonlinear optical susceptibility were enhanced after thermal annealing treatment. The OKE response of the as-deposited film was instantaneous, and the enhanced OKE signal of the annealed film presented additional slow decay processes which imply the important contribution from photoinduced hot electrons in Cu nanoparticles.

Synthesis and characterization of metal ion imprinted nano-porous polymer for the selective recognition of copper

Selective recognition of metal ions utilizing metal ion-imprinted polymers (MIIPs) received much importance in diverse fields owing to their high selectivity for the target metal ions. In the present study, a copper ion imprinted polymer was synthesized without an additional complexing ligand or complex with a broad aim to avoid the conventional extra metal ion complexing ligand during the synthesis of MIIP. The complete removal of the copper metal ion from the MIIP was confirmed by AAS and SEM–EDX. SEM image of the MIIP exhibited nano-patterns and it was also found to be entirely different from that of non-imprinted polymer and polymer with copper metal ions. BET surface area analysis revealed more surface area (47.96m2/g) for the Cu(II)-MIIP than non-imprinted control polymer (41.43m2/g). TGA result of polymer with copper metal ion indicated more char yield (18.41%) when compared to non-imprinted control polymer (8.3%) and Cu(II)-MIIP (less than 1%). FTIR study confirmed the complexation between Cu(II)-MIIP and Cu(II) metal ion through carbonyl oxygen of acryl amide. The Cu(II)-MIIP exhibited an imprinting efficiency of 2.0 and it was showing 8% interference from a mixture of Zn, Ni and Co ions. A potentiometric ion selective electrode devised with Cu(II)-MIIP showed more potential response for Cu(II) ion than that was fabricated from non-imprinted polymer.

Aging response and its effect on the functional properties of Cu–Al–Ni shape memory alloys

The β-phase aging response of Cu–Al–Ni single crystal shape memory alloys (SMAs) within the temperature range of 473–573 K has been investigated. Alloys in austenitic (Cu–14.1Al–4Ni wt.%, alloy A) and martensitic (Cu–13.4Al–4Ni wt.%, alloy M) conditions at room temperature were considered. Aged samples show presence of β 1′ and γ 1′ martensites in both the alloys and formation of γ 2 precipitates in the alloy A. The differential scanning calorimetry (DSC) thermograms of the aged samples show increase in transformation temperatures as well as transformation hysteresis with aging. Dynamic mechanical analysis (DMA) was conducted on both the alloys to ascertain the role of precipitates and martensitic transition on tan δ, which characterizes the damping behaviour of the material. With aging, a steady decrease in tan δ value was observed in both the alloys, which was attributed to the decrease in the number of interfaces per unit area with increasing aging temperature. Moreover, in alloy A, as the volume fraction of precipitate increases with aging, the movement of martensitic interfaces is restricted causing a decreased tan δ.

Finite element simulation of martensitic transition based on thermo-mechanical model

Martensitic phase transition and martensite phase have an important effect on the physical and deformation properties of a material. In this paper, martensitic phase transition in elastic materials is modeled by using thermo-mechanical phenomenological theory. Based on the model proposed, stress-induced martensitic transition in Cu–Zn–Al shape memory alloy is studied by using finite element method. Stress–strain responses of Cu–Zn–Al single crystals under different applied stress rate are simulated by thermo-mechanically coupled calculation. Pseudoelastic deformation, hysteresis of transformation and hardening in stress–strain response are predicted in calculation results. Stress–strain curves determined from numerical simulation have a good agreement with those observed in experiments.

Direct Nitric Oxide Detection in Aqueous Solution by Copper(II) Fluorescein Complexes

A series of FL(n) (n = 1-5) ligands, where FL(n) is a fluorescein modified with a functionalized 8-aminoquinoline group as a copper-binding moiety, were synthesized, and the chemical and photophysical properties of the free ligands and their copper complexes were investigated. UV-visible spectroscopy revealed a 1:1 binding stoichiometry for the Cu(II) complexes of FL(1), FL(3), and FL(5) in pH 7.0 buffered aqueous solutions. The reactions of FL(2) or FL(4) with CuCl(2), however, appear to produce a mixture of 1:1 and 1:2 complexes, as suggested by Job's plots. These binding modes were modeled by the synthesis and X-ray crystal structure determination of Cu(II) complexes of 2-[(quinolin-8-ylamino)methyl]phenol (modL), employed as a surrogate of the FL(n) ligand family. Two kinds of crystals, [Cu(modL)(2)](BF(4))(2) and [Cu(2)(modL')(2)(CH(3)OH)](BF(4))(2) (modL' = 2-[(quinolin-8-ylamino)methyl]phenolate), were obtained. The structures suggest that one oxygen and two nitrogen atoms of the FL(n) ligands most likely bind to Cu(II). Introduction of nitric oxide (NO) to pH 7.0 buffered aqueous solutions of Cu(FL(n)) (1 microM CuCl(2) and 1 microM FL(n)) at 37 degrees C induces an increase in fluorescence. The fluorescence response of Cu(FL(n)) to NO is direct and specific, which is a significant improvement over commercially available small molecule-based probes that are capable of detecting NO only indirectly. The NO-triggered fluorescence increase of Cu(FL(5)) occurs by reduction of Cu(II) to Cu(I) with concomitant dissociation of the N-nitrosated fluorophore ligand from copper. Spectroscopic and product analyses of the reaction of the FL(5) copper complex with NO indicated that the N-nitrosated fluorescein ligand (FL(5)-NO) is the species responsible for fluorescence turn-on. Density functional theory (DFT) calculations of FL(5) versus FL(5)-NO reveal how N-nitrosation of the fluorophore ligand brings about the fluorescence increase. The copper-based probes described in the present work form the basis for real-time detection of nitric oxide production in living cells.

Ab initio study of the optical response of Cu(0 0 1) surface

We present ab initio density functional calculation of the optical properties of Cu(0 0 1) surface, carried out using interband transitions based on energy bands calculated through ab initio self-consistent method of linear muffin tin orbitals (LMTO). The imaginary part of the dielectric function ϵ 2( ω) exhibits three dominant peaks and two small shoulder-like structures. Three of them, located at 0.53 eV, 2.73 and 3.39 eV, are obtained for a light polarized parallel to the Cu(0 0 1) surface whereas the two others, at 1.70 and 2.73 eV, are due to photons polarized in the direction perpendicular to the surface. We show that not all the peaks have their origin in interband transitions involving localized states, but also in electronic transitions between parallel energy bands. All these transitions are identified by their orbital symmetries and by the atomic sites involved in the process.

Selective electrochemical sensor for copper (II) ion based on chelating ionophores

Plasticized membranes using 3-(2-pyridinyl)-2H-pyrido[1,2,-a]-1,3,5-triazine-2,4(3H)-dithione ( L 1) and acetoacetanilide ( L 2) have been prepared and explored as Cu 2+-selective sensors. Effect of various plasticizers, viz. chloronaphthalene (CN), benzyl acetate (BA), o-nitrophenyloctyl ether ( o-NPOE), and anion excluders, sodium tetraphenylborate (NaTPB) and oleic acid (OA) was studied in detail and improved performance was observed at several instances. Optimum performance was observed with dithione derivative ( L 1) having a membrane composition of L 1 (5):PVC (120): o-NPOE (240):OA (10). The sensor works satisfactorily in the concentration range 5.0 × 10 −8 to 1.0 × 10 −2 M (detection limit 4.0 × 10 −8 M) with a Nernstian slope of 29.5 mV decade −1 of activity. Wide pH range (3.0–9.5), fast response time (12 s), non-aqueous tolerance (up to 20%) and adequate shelf life (4 months) indicate the vital utility of the proposed sensor. The potentiometric selectivity coefficient values as determined by match potential method (MPM) indicate good response for Cu 2+ in presence of interfering ions. The proposed electrode comparatively shows good selectivity with respect to alkali, alkaline earth, transition and some rare earth metals ions. The electrode was used for the determination of copper in different milk powder, water samples and as indicator electrode in potentiometric titration of copper ion with EDTA.

Synthesis and Cu(II) coordination of two new hexaamines containing alternated propylenic and ethylenic chains: Kinetic studies on pH-driven metal ion slippage movements

The synthesis of the open-chain and cyclic polyamines, 1,5,8,12,15,19-hexaazaheptadecane (L1) and 2,6,9,13,16,20-hexaaza[21]-(2,6)-pyridinophane (L2), are described. The protonation constants and interaction constants with Cu(II) have been determined by potentiometric measurements carried out at 298.1 K in 0.15 mol dm −3 NaClO 4. The values obtained are discussed as a function of the open-chain or cyclic nature of the ligands and compared with analogous polyamines containing different sets of hydrocarbon chains between the nitrogen donors. Kinetic studies on the acid-promoted dissociation of the Cu(II) complexes indicate that the mono and binuclear complexes of L1 decompose with different kinetics, a behavior unprecedented for open-chain polyamines. In contrast, the dissociation of the first metal ion is accelerated in the binuclear complexes of L2 and so, all the mono and binuclear complexes of L2 decompose with the same kinetics. The voltammetric response of Cu(II)–L1 and Cu(II)–L2 complexes has been studied in order to correlate electrochemical and structural data.

Copper(II)-selective potentiometric sensors based on porphyrins in PVC matrix

Cu 2+ selective sensors have been fabricated from polyvinyl chloride (PVC) matrix membranes containing neutral carrier porphyrin ( A and B) ionophores. The addition of sodium tetraphenylborate and the plasticizer DOP has been found to substantially improve the performance of the sensors. The membranes of various compositions of the two porphyrins were investigated and it was found that the best performance was obtained for the membrane of composition B:PVC:NaTPB:DOP in the ratio 5:150:2:150. The sensor shows a linear potential response for Cu 2+ over a wide concentration range 4.4 × 10 −6 to 1.0 × 10 −1 M with Nernstian compliance (29.3 mV decade −1 of activity) between pH 2.8 and 7.9 and a fast response time of ∼8 s. The potentiometric selectivity coefficient values as determined by fixed interference method indicate excellent selectivity for Cu 2+ ions over interfering cations. The sensor exhibits adequate shelf life (∼4 months) with good reproducibility (standard deviation ± 0.2 mV). The sensor can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working concentration range. The sensor has been used in the potentiometric titration of Cu 2+ with EDTA. The utility of the sensor has been tested by determining copper in vegetable foliar and swimming pool water sample successfully.

Development of a New Copper(II) Ion-selective Poly(vinyl chloride) Membrane Electrode Based on 2-Mercaptobenzoxazole

Copper(II) ion-selective PVC membrane electrode based on 2-mercaptobenzoxazole as a new ionophore and o-nitrophenyl octyl ether (o-NPOE) as plasticizer is proposed. This electrode revealed good selectivity for Cu 2 + overa wide variety of other metal ions. Effects of experimental parameters such as membrane composition, nature and amount of plasticizer, and concentration of internal solution on the potential response of Cu 2 + sensor were investigated. The electrode exhibits good response for Cu 2 + in a wide linear range of 5.0 x 10 - 6 -1.6 x 10 - 2 mol/L with a slope of 29.2 ′ 2.0 mV/decade. The response time of the sensor is less than 10 s, and the detection limit is 2.0 x 10 - 6 mol/L. The electrode response was stable in pH range of 4-6. The lifetime of the electrode was about 2 months. The electrode revealed comparatively good selectivities with respect to many alkali, alkaline earth, and transition metal ions.

Stress response in Cu 2+ and Cd 2+ exposed oysters ( Crassostrea gigas): An immunohistochemical approach

Localization of heat shock proteins (HSPs) and metallothioneins (MTs) was investigated in a marine bivalve ( Crassostrea gigas) by immunohistochemical methods. Differential protein expression was demonstrated in digestive gland, gonad and gills, using a polyclonal antibody against C. gigas proteins. Application of this technique showed the cellular and tissue immunolabelling specificity of the two proteins. HSPs and MTs were localized in the epithelium of the digestive gland and gills in contact with the palleal compartment. For the first time, localization of MTs was observed in mature gametes of bivalve molluscs. Our results establish a basis for the use of immmunodetection techniques to study the tissue-specific localization of stress proteins in marine bivalves exposed to metal stress.

Copper(II) selective electrochemical sensor based on Schiff Base complexes

Plasticized membranes using Schiff Base complexes, derived from 2,3-diaminopyridine and o-vanilin have been prepared and explored as Cu 2+-selective sensors. Effect of various plasticizers viz., dibutyl phthalate (DBP), dioctylphthalate (DOP), chloronaphthalene (CN), tri- n-butylphosphate (TBP) etc. and anion excluder, sodium tetraphenylborate (NaTPB) was studied in detail and improved performance was observed at several instances. Optimum performance was observed with Schiff Base (B) having a membrane composition of B(1%):PVC(33%):DOP(65%):NaTPB(1%). The sensor works satisfactorily in the concentration range 5.0×10 −6 to 1.0×10 −1 M (detection limit 0.3 ppm) with a Nernstian slope of 29.6 mV per decade of activity. Wide pH range (1.9–5.2), fast response time (<30 s), high non-aqueous tolerance (up to 20%) and adequate shelf life (>4 months) indicate the vital utility of the proposed sensor. The potentiometric selectivity coefficient values as determined by match potential method (MPM) indicate good response for Cu 2+ in presence of interfering ions. The tolerance level of Hg 2+, which causes serious interference in the determination of Cu 2+ ions ( K Cu 2+Hg 2+ Pot(MPM): 0.45), was determined as a function of Cu 2+ concentration in simulated mixtures. The sensor was also used in the potentiometric titration of Cu 2+ with EDTA.

Reflection anisotropy spectroscopy of molecular assembly at metal surfaces

Reflection anisotropy spectroscopy (RAS) is a non-destructive optical probe of surfaces capable of operation within ultra-high vacuum and liquid environments. The RAS technique has been used to investigate the behaviour of surface electronic states on clean metal surfaces including energy shifts, depopulation and quantum confinement. RAS has been used to monitor the first stages of molecular assembly on metal surfaces in UHV and at the solid–liquid interface. Sensitivity to adsorbate-surface bond formation and molecular orientation has been demonstrated. The Cu(110) and Au(110) surfaces have been the focus for RAS studies of molecular assembly in UHV and liquid environments, respectively. In this article, some aspects of the RA response of Cu(110) and Au(110) are described and the potential of RAS as a probe of molecular assembly at these surfaces is discussed.

The influence of Cu adatoms on the Zn upd on polycrystalline thin gold film electrodes: a study using surface conductance measurements

The adsorption behaviour of Zn upd and irreversibly adsorbed Cu on thin gold films in a NaH 2PO 4 electrolyte was studied applying both CV and surface conductance (SC) measurements. These processes were studied separately and the upd of Zn in the presence of previously adsorbed Cu was also studied. Zn upd and ups occur with an apparent number of transferred electrons n=1. The SC measurements show that Zn upd does not conform the surface Linde rule. The n value obtained can be explained by considering that the product is not Zn(0). The SC response of Cu irreversibly adsorbed on gold shows an increase in SC as the degree of coverage increases. The voltammetric response for the upd of Zn on Cu-covered gold electrodes shows that a Cu coverage around θ Cu∼0.66 is enough to inhibit the Zn upd process on gold completely. The charge relation ( Q Cu vs. Q Zn) shows that one Cu adatom blocks one Zn site. The SC shows that the response of Zn on Cu pre-adsorbed on gold is additive. This last behaviour can be explained only by inferring a phase segregation in two dimensions where Cu and Zn depositions occur in the form of individual islands.

A Study of the Strain Rate Microstructural Response and Wear of Metals

Titanium (Ti) and copper (Cu) pins were slid against alumina in a pin-on-disk machine at a load of 50 N and sliding speeds varying from $0.1 \hspace {2mm} to \hspace {2mm} 4 ms^{-1}$. The evolution of the microstructure in the subsurface of the material and the wear rate was co-related to the strain rate microstructural response of the material in uniaxial compression, at different strain rates $(0.1-100 \hspace {2mm} s^{-1})$ and temperatures (298-673 K). The strain rates and temperatures in the plastically deforming zone near the surface of the pins were determined using noniterative methods. The strain rates were found to be in the region of $100 \hspace {2mm} s^{-1}$ near the surface and decreases as one moves into the sub-surface of the pin. The temperatures increased as the speed increased. These estimated strain rates and temperatures were superimposed on the strain rate microstructural response maps of these materials. The uniaxial compression test results of Ti showed adiabatic shear banding as a microstructural mechanism that evolves at high strain rates $(\geq 10 \hspace {2mm} s^{-1})$ and lower temperatures (<575 K). Adiabatic shear bands are sites of easy crack nucleation and propagation. When Ti is slid at low speeds the near surface region of the pins deform in the adiabatic shear banding regions in the strain rate microstructural response map. At such speeds the wear rate is found to be high and reduces as the sliding speed is increased, when the material undergoes a more homogeneous deformation. The microstructural response of Cu under uniaxial compression showed that the material undergoes flow banding at intermediate strain rates $(1 \hspace {2mm} s^{-1})$ and temperatures of up to 473 K. The subsurface microstructure of the pins slid at low speeds showed subsurface cracking and sheet like debris formation. This happen at lower speeds because the flow banding and crack nucleation is expected in the subsurface where the strain rates and temperatures are lower. The present test results show a clear relation to exist between the strain rate response of the material in uniaxial compression and its subsurface microstructural evolution and wear rate.

Stress reduction experiments during constant-strain-rate tests in Cu and Ge

The technique of rapid reductions in applied stress (dip test) is occasionally performed in creep testing. In the work reported here, the technique was applied during a constant-strain-rate test. Both variants, the stress dip test and the strain dip test, give equivalent results. The specimen strain has to be measured in both cases; however, the strain dip technique is preferred since anelastic effects do not interfere. It is shown that the response of Cu and Ge single crystals to fast stress reductions, on the level of the internal stress and below it, is strongly material dependent, reflecting differences in microstructural processes involved in the plastic deformation. These processes are discussed.

Effects of Several Metals on Both Fe(III)‐ and Cu(II)‐Reduction by Roots of Fe‐Deficient Cucumber Plants

The ferric‐chelate reductase induced by Fe deficiency is also able to reduce other ions such as Cu2+. This Cu(II)‐reduction has been less studied and it has been suggested that Cu2+ ion rather than Cu2+‐chelate serves as the substrate. Ferric‐chelate reductase activity is inhibited by some metals, but the mechanisms implicated are not known. In the present work we use Fe‐deficient cucumber seedlings to study the interactions of Cu2+, Ni2+, Mn4+, and Fe3+ on both Fe(III)‐reduction and Cu(II)‐reduction activities. The response of Cu(II)‐reduction activity to Cu concentration, in the presence or absence of citrate, was also studied. Results showed that inhibition of the ferric‐chelate reductase activity by Cu2+ or Ni2+ could be partially reversed by increasing the concentration of Fe‐EDTA. The Cu(II)‐reduction activity was even stimulated by Fe‐EDTA or Ni2+; it was inhibited by a high concentration of Cu2+ itself; and it was not affected by the absence of citrate. Mn4+ caused a moderate inhibition of both Fe(III)‐reduction and Cu(II)‐reduction activities. Results agree with the hypothesis that free Cu2+ ion is the substrate for Cu(II)‐reduction and suggest that the mechanisms involved in Fe(III)‐reduction and Cu(II)‐reduction could have some differences and be affected by metals in different ways. The mode of action of metals on the reductase activity are discussed, but they are still not well known.

Effects of long-range interactions in metal epitaxial growth

The van der Waals constant ${C}_{3}$ describing the long-range attractive interaction between a Cu atom and a Cu(100) surface is calculated, along with the dominant correction ${z}_{0}$ for the shift in the reference plane, using expressions derived by Persson and Zaremba which take into account the optical response of Cu. The result ${C}_{3}\ensuremath{\simeq}2.1\mathrm{eV}{\mathrm{\AA{}}}^{3}$ is significantly smaller than predicted by a simple Lennard-Jones (LJ) Cu potential used in recent simulations, but large enough to explain experimental observations of a significant increase in mound angle in Cu/Cu(100) growth for large angles of incidence. In contrast, trajectory calculations indicate that the LJ Cu potential appears to overestimate the effects of long-range attraction. Our results also indicate that for small angles of incidence $(\ensuremath{\theta}&lt;50\ifmmode^\circ\else\textdegree\fi{}),$ the dominant effects of attraction on the surface morphology in Cu/Cu(100) growth are related to the short-range rather than to the long-range interaction. Similar results are presented for Ag/Ag(100).

An effective-medium approach to the optical properties of heterogeneous materials with nonlinear properties

We have derived an analytic approach, based on the hypothesis of the effective-medium theory, to evaluate the effective dielectric magnitudes, including the effective third order nonlinear optical susceptibility α(χ(3)), of a heterogeneous two-component medium in which one of the components (the host matrix or the embedded particle respectively) presents nonlinear behaviour. Our formulation allows us to solve the full nonlinear problem in the whole range of concentrations without treating the nonlinear effects as a small perturbation to the linear behaviour. Therefore, it can be considered as an upper limit of the commonly used low-field nonlinear approximations for heterogeneous materials. Under certain conditions, these composites can exhibit a bistable regime that the present theory properly describes in wide ranges of the concentration, shape, wavelength, dielectric contants and intrinsic nonlinear optical susceptibility of the nonlinear component as well as in terms of the intensity of the external electric field. The present approach has been used to calculate the nonlinear optical response of Cu—Al2O3 nanocomposites.

Highly selective copper membrane electrode using C-p-nitrophenyl-N-phenylnitrone

The construction, performance characteristics and applications of a polymeric membrane electrode for Cu(II) ion are reported. The electrode was prepared by incorporating C-p-nitrophenyl-N-phenylnitrone as the charge carrier into a plasticized poly(vinyl chloride) membrane. The influence of membrane composition, pH and concentration of the solution were investigated. The electrode exhibits a potentiometric response for Cu2+ ion over the concentration range 1 × 10−6–1 × 10−1 M with a detection limit of 5 × 10−7 M Cu2+. It shows a relatively fast response time of about 15 s and can be used for about two months without any considerable divergence in potential. The electrode can be used at a pH of between 4.0–8.0. The selectivity of proposed electrode for Cu2+ in the presence of several metal ions. It was used as an indicator electrode in the potentiometric titration of Cu2+ with EDTA.