Transfer Of Cu Research Articles

Biofilm's morphology design for high sensitivity of bioelectrochemical sensor: An experimental and modeling study

High sensitivity is essential for the application of bioelectrochemical system-based sensor (BES sensor) in water quality early-warning, where the electroactive biofilm is of vital importance as it delivers a responsive electric signal to toxic substances. This study artificially designed the morphology of a naturally formed biofilm by employing a serrated knife to scrape the biofilm and thus obtained a reduced thickness and roughness. Then it was further cut by half to halve the biomass. BES sensors equipped with control and processed biofilms were operated under constant anode potential (CAP) and tested at different Cu(II) concentrations to study their sensitivities. Results revealed that the scraped biofilms delivered much increased sensitivity towards Cu(II) shock, which was attributed to a reduced thickness as illustrated by macroscopic and microscopic morphology analysis. Another finding was that biomass per unit interfacial area, rather than the biomass, also affected the sensitivity. To further describe how the inner biofilm responded the toxicity after morphology design, a one-dimension mass transfer model was developed to simulate the mass transfer of Cu(II) in the biofilms with different thicknesses. The relative threshold value of inlet Cu(II) concentration was employed to fit the modeling and experimental results, indicating that decreased biofilm thickness was beneficial for improving the sensitivity.

Heavy metal copper accelerates the conjugative transfer of antibiotic resistance genes in freshwater microcosms

Recent studies have consistently demonstrated increasing abundances of antibiotic resistance genes (ARGs) in the absence of antibiotic use. There is a large amount of quantitative data that has correlated the elevated ARGs levels with the concentrations of heavy metals in environments with anthropogenic impact. However, the mechanisms by which heavy metals facilitate the proliferation and horizontal gene transfer of ARGs among environmental bacteria were still unknown. This study validated effects of four typical heavy metals (Cu, Cd, Pb, Zn) on the plasmid RP4 mediated conjugative transfer of ARGs in freshwater microcosms. The results suggested that the typical heavy metals including Cu, Pb and Zn would promote conjugative transfer of the plasmid RP4, and Cu (5.0 μg/L) had the greatest ability to increase conjugative transfer by 16-fold higher than the control groups. In conjugative transfer microcosms, the species of each cultivable transconjugant were isolated, and their minimum inhibitory concentrations (MICs) were assessed via antibiotic susceptibility testing. The mechanism of the increased conjugative transfer of Cu was that Cu induced cell damage and the reduced conjugative transfer of Cd was that Cd increased the content of extracellular polymers substances (EPS). This study confirms that heavy metal Cu facilitates the conjugative transfer of environmental-mediated plasmid RP4 by cell damage effect, therefore accelerating the transmission and proliferation of ARGs.

Phase transfer of metal cations by induced dynamic carrier agents: biphasic extraction based on dynamic covalent chemistry.

In contrast to the classical method where a single molecule is designed to extract metal cations under specific conditions, dynamic covalent chemistry provides an approach based on the implementation of an adaptive dynamic covalent library for inducing the generation of the extractant species. This approach has been applied to the liquid–liquid extraction of copper(ii) nitrate based on a dynamic library of acylhydrazones constituents that self-build and distribute through the interface of a biphasic system. The addition of copper(ii) cations to this library triggers a modification of its composition and the up-regulation of the ligand molecules driven by coordination to the metal cations. Among these, one species has proven to be sufficiently lipophilic to play the role of carrier agent and its formation by component exchange enables the partial extraction of the copper(ii). The study of different pathways to generate the dynamic covalent library demonstrates the complete reversibility and the adaptability of the system. The detailed analytical investigation of the system provides a means to assess the mechanism of the dynamic extraction process.

Incidence risk of bronchopneumonia in newborn calves associated with intrauterine diselementosis.

Background and Aim:Macro- and micro-elements are required to ensure the normal course of biochemical processes in the development of an animal’s body. Any excess, deficiency, or imbalance in chemical elements in an animal’s body can cause the development of various latent or clinically expressed pathological conditions. Diselementosis in pregnant cows may lead to impaired embryo and fetal development, as well as reduced neonatal viability. The aim of this study was to analyze the content of macroelements and microelements in the blood serum of both calving cows and their calves to evaluate the relationship between indicators of mineral metabolism in the mother and newborn and to establish what role separate chemical elements play in making newborn calves more prone to bronchopneumonia.Materials and Methods:The content of potassium (K), sodium (Na), iron (Fe), Copper (Cu), Zinc (Zn), Strontium (Sr), arsenic (As), nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), and selenium (Se) in the blood serum of 33 pregnant cows between 239 and 262 days of gestation and their 33 1-day old calves was determined using the Shimadzu AA6300 (Japan) atomic adsorption spectrophotometer. Calcium (Ca) and magnesium (Mg) content was determined using ion-selective electrodes from the Olympus-400 analyzer (Beckman Coulter, USA). During the 1st month of life, all calves in the sample set had some sort of respiratory diseases and seven of the calves had bronchopneumonia. Retrospectively, the samples of adult and newborn animals were divided into two groups each: Dams I – cows whose calves had uncomplicated bronchitis (n=26); Dams II – cows whose calves got bronchopneumonia (n=7); and Newborns I – calves with uncomplicated bronchitis (n=26); Newborns II – calves with bronchopneumonia (n=7).Results:The content of Ca, Mg, K, Na, Mo, and Se in dams in both groups of cows was within the reference range; the concentrations of Fe and Ni were higher than the reference range; and the concentrations of Cu, Zn, As, Co, and Cr were lower than the reference range. There were no significant differences in elemental status between the Dams I and Dams II groups. In newborn calves, the concentration of Ca and Mo corresponded to the reference range; the concentrations of Mg, Fe, Co, and Ni in both groups exceeded the reference range; and the concentrations of Cu, Zn, As, Cr, and Se were lower than the reference range. Results highlighted that there was a tendency to decrease concentration of Fe, Mo, and Se and a significant increase in the Ni concentration in calves of the Newborns II group compared with calves of the Newborns I group. It was also found that Zn, Co, Cr, and Mo actively accumulated in the body of newborn animals while the transplacental transfer of Cu, As, and Sr was limited; and transfer of Se and Ni was regulated by concentration ratios in the blood of the mother and the fetus. The excessive concentrations of Ni and Fe in the blood serum of cows and calves and the imbalance in the ratio of elements Fe–Cu–Zn, Fe–Cu–Co negatively affected erythropoiesis, formation of the immune system, and antioxidant status of the fetus and newborn. These changes were considered to be risk factors for the development of bronchopneumonia in calves.Conclusion:An excess of serum Fe and Ni and deficiency of Cu, Zn, As, Co, and Cr in cows during the gestation period can lead to similar impairments of the mineral status in newborn calves. At the systemic level, dyslementosis in combination with the influence of other adverse factors, can lead to an increased load on the respiratory and hematopoietic systems of calves during postnatal adaptation and can subsequently cause a decrease in the natural resistance of calves and development of bronchopneumonia.

Zero Cu valence and superconductivity in high-quality CuxBi2Se3 crystal

In this work, the role of Cu dopants in the development of superconductivity in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is investigated. A series of $\mathrm{C}{\mathrm{u}}_{x}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ ($x=0--0.3$) crystals is grown using the Bridgman method and electrochemical techniques. Based on the observable lattice increases along the $c$ axis, the existence of Cu atoms intercalated in the van der Waals (vdW) gaps in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is verified by x-ray diffraction, scanning electron microsopy--energy dispersive spectroscopy, and transmission electron microscopy analysis. Furthermore, the chemical state of the Cu is found to be zero valence by characterization of the x-ray photoelectron and Auger electron spectra. The absence of $\mathrm{C}{\mathrm{u}}^{1+}$ and $\mathrm{C}{\mathrm{u}}^{2+}$ in the electron energy-loss spectroscopy near-edge fine structure is confirmed as well. Meanwhile, our Raman data also show the same result: the intercalation of Cu in the vdW gap which weakens the binding of the quintuple layers in the $\mathrm{C}{\mathrm{u}}_{0.1}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ crystal. The electric resistance and magnetic susceptibility show a superconducting transition near 3--3.4 K in the series of Cu-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. A sharp superconducting transition with the highest value of ${T}_{C}=3.4\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and the largest magnetic shielding fraction of 84% is observed in the optimized 10% Cu-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. These results imply that the formation of superconducting quasiparticles is not related to the charge transfer of Cu, but is supported by the internal stress of Cu intercalated in the van der Waals gap. The superconducting transition observed in the specific heat implies that the superconductivity in $\mathrm{C}{\mathrm{u}}_{x}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is unconventional.

Serum and brain natural copper stable isotopes in a mouse model of Alzheimer\u2019s disease

Alzheimer’s disease is associated with the production of Cu rich aβ fibrils. Because monitoring the changes in Cu level of organs has been proposed to follow the evolution of the disease, we analyzed the copper isotopic composition of serum and brain of APPswe/PSEN1dE9 transgenic mice, a model of Alzheimer’s disease, and wild-type (WT) controls. Serum composition of 3, 6, 9 and 12-month-old mice, as well as the composition of 9 brains of 12-month-old mice are reported. In WT mice, brains were ~1‰ isotopically heavier than serum, and the Cu isotopic composition of the serum was isotopically different between males and females. We propose that this effect of sex on the Cu isotopic budget of the serum may be related to a difference of Cu speciation and relative abundance of Cu carriers. Brains of APPswe/PSEN1dE9 mice were slightly lighter than brains of WT mice, while not statistically significant. This trend may reflect an increase of Cu(I) associated with the formation of Aβ fibrils. The Cu isotopic composition of the brains and serum were correlated, implying copper transport between these two reservoirs, in particular a transfer of Cu(I) from the brain to the serum. Altogether, these data suggest that Cu stable isotopic composition of body fluid may have the potential to be used as detection tools for the formation of Aβ fibrils in the brain, but further work has to be done.

Application of metal-organic framework as redox probe in an electrochemical aptasensor for sensitive detection of MUC1

In this work, an electrochemical aptasensor was developed for sensitive detection of MUC1 based on metal-organic framework-reduced graphene oxide nanocomposite (Cu-MOF-RGO). Cu- MOF-RGO appeared to be suitable as a platform for immobilization of MUC1 aptamer, and also as an electrochemical probe, which exhibited well-defined peaks with good stability and reproducibility. Cu-MOF-graphene oxide (Cu-MOF-GO) nanocomposite was prepared and cast on the electrode surface, then in order to increase the conductivity of the electrode, GO was electrochemically reduced to RGO. In the presence of MUC1, the peak current of Cu in the nanocomposite decreased, which could be explained based on the formation of MUC1–aptamer complexes on the electrode, and consequence blocking the electron transfer of Cu at the electrode surface. Under optimum experimental conditions, a linear calibration curve was obtained by differential pulse voltammetry in the concentration range of 0.1 pM–10 nM (25 pg mL−1 – 2500 ng mL−1) with a limit of detection (LOD) of 0.033 pM (7.5 pg mL−1) of MUC1. The proposed aptasensor offers acceptable selectivity, stability, and reproducibility in the determination of MUC1 spiked to human blood serum samples.

Cu(II) Binding to the N-Terminal Model Peptide of the Human Ctr2 Transporter at Lysosomal and Extracellular pH.

It was shown that His3 of human copper transporter 1 (hCtr1) prompts the ATCUN-like Cu(II) coordination for model peptides of the hCtr1 N-terminus. Its high Cu(II) affinity is a potential driving force for the transfer of Cu(II) from extracellular Cu(II) carriers to hCtr1. Having a sequence similar to that of hCtr1, hCtr2 has been proposed as another human copper transporter. However, the N-terminal domain of hCtr2 is much shorter than that of hCtr1, with different copper binding motifs at its N-terminus. Employing a model peptide of the hCtr2 N-terminus, MAMHF-am, we demonstrated that His4 provides a unique pattern of Cu(II) complexes, involving Met sulfurs in their Cu(II) coordination sphere. The affinity of Cu(II) for MAMHF-am is a few orders of magnitude lower than that reported for the hCtr1 model peptides at the extracellular pH of 7.4, suggesting a maximal complementary role of Cu(II) binding to hCtr2 in the import of copper from the extracellular space to the cytoplasm. On the other hand, the ability of the hCtr2 model peptide to capture Cu(II) from amino acids and short peptides (potential degradation products of proteins) at pH 5.0 and the known predominant lysosomal localization of hCtr2 support an important potential role of the Cu(II)-hCtr2 interaction in the recovery of copper from lysosomes.

Combined MHD convection and thermal radiation of nanofluid in a lid-driven porous enclosure with irregular thermal source on vertical sidewalls

Mixed convective heat transfer of Cu–water nanofluid in a porous cavity with non-uniform temperature profiles on vertical sidewalls in the presence of thermal radiation and magnetic field is examined numerically. The vertical sidewalls are heated sinusoidally. Thermally insulated walls are considered at the remaining sides of the cavity. The magnetic field is applied parallel to the horizontal walls uniformly. The SIMPLE algorithm based on finite volume approach is applied to solve the governing equations. The numerical outcomes are discussed in the wide range of the parameters, Richardson number, phase deviation, amplitude ratio, Darcy number, Hartmann number, the thermal radiation, and the solid volume fraction. It is found that the average Nusselt number is decreased in value with the raise in the either Hartmann number or Richardson number in the presence of thermal radiation. The average heat transfer rate is enhanced with an augment in the solid volume fraction, and this enhancement is more effective in the presence of thermal radiation than that of in the absence of thermal radiation. The highest heat transfer rate is obtained for $$\varphi =0$$ in the forced convection regime, whereas it is maximum at $$\varphi =3\pi /4$$ in the mixed and free convection regimes.

Void and secondary phase formation mechanisms of CZTSSe using Sn/Cu/Zn/Mo stacked elemental precursors

In recent years, Cu2ZnSn(S1-xSex)4 (CZTSSe) prepared by a two-step process using metal precursors has been reported to exhibit a relatively high power conversion efficiency, and a high efficiency of 12.5% by two-step process contained via sputtering method was recently confirmed by our group. In this study, we proposed formation mechanisms for the CZTSSe double layer, voids and ZnSSe layer, which were observed in the CZTSSe using metal precursor. Due to the persistent dezincification from the metal precursors and preferential reaction between the Zn and chalcogens such as S and Se, almost all Zn is consumed to form the ZnSSe layer; as a result, large voids are produced first under the ZnSSe layer. Cu2Se and SnSe are grown on the ZnSSe layer via migration of the Cu and Sn through the grain boundaries of the ZnSSe layer. Thus, additional small voids are expected to form due to the mass transfer of Cu and Sn. Because of the preferentially formed ZnSSe layer and the chalcogenation of Cu and Sn after the mass transfer, a CZTSSe double layer can be formed, and ZnSSe can exist between these CZTSSe layers. Finally, we propose a method based on the formation mechanism to control the voids and secondary phases, which affect the fill factor and output current.

Effect of ethylenediaminetetraacetic acid and biochar on Cu accumulation and subcellular partitioning in Amaranthus retroflexus L.

Phytoremediation combined with amendments and stabilization technologies are two crucial methods to deal with soil contaminated with heavy metals. Copper (Cu) contamination in soil near Cu mines poses a serious threat to ecosystems and human health. This study investigated the effect of ethylenediaminetetraacetic acid (EDTA) and biochar (BC) on the accumulation and subcellular distribution of Cu in Amaranthus retroflexus L. to demonstrate the remediationmechanism of EDTA and BC at the cellular level. The role of calcium (Ca) in response to Cu stress in A. retroflexus was also elucidated. We designed a pot experiment with a randomized block of four Cu levels (0, 100, 200, 400mgkg-1) and three treatments (control, amendment with EDTA, and amendment with BC). The subcellular components were divided into three parts (cell walls, organelles, and soluble fraction) by differential centrifugation. The results showed that EDTA amendment significantly increased (p < 0.05) the concentrations of Cu in root cell walls and all subcellular components of stems and leaves (cell walls, organelles, and the soluble fraction). EDTA amendment significantly increased (p < 0.05) the proportion of exchangeable fraction and carbonate fraction in the soil. While BC amendment significantly decreased (p < 0.05) the concentrations of Cu in root cell walls and the root soluble fraction, it had no significant effects on Cu concentrations in the subcellular components of stems and leaves. The results revealed that EDTA mainly promoted the transfer of Cu to aboveground parts and accumulation in subcellular components of stems and leaves, while BC mainly limited Cu accumulation in root cell walls and the root soluble fraction. Ca concentrations in cell walls of roots, stems, and leaves increased as the Cu stress increased in all treatment groups, indicating that Ca plays an important role in relieving Cu toxicity in Amaranthus retroflexus L.

Comparing plant–insect trophic transfer of Cu from lab-synthesised nano-Cu(OH)2 with a commercial nano-Cu(OH)2 fungicide formulation

Environmental contextNanomaterials are being extensively researched for use as agrochemicals, and some commercial formulations containing nanomaterials are already on the market. Information on environmental fate and effects of nanomaterials, however, are largely based on laboratory-synthesised materials. This study questions whether data on trophic transfer of Cu from pure, laboratory-synthesised Cu(OH)2 nanomaterials can be used to predict trophic transfer of Cu from a complex commercial fungicide formulation containing Cu(OH)2 nanomaterials. AbstractTo examine whether studies conducted with highly purified, laboratory-synthesised nanomaterials are predictive of behaviour of commercial nanopesticide formulations, we studied the trophic transfer of Cu(OH)2 manufactured nanomaterials (MNMs) by tobacco hornworms (Manduca sexta) feeding on surface-treated tomato leaves (Solanum lycopersicum). We compared laboratory-synthesised copper(II) hydroxide (Cu(OH)2) nanowire with the widely used fungicide Kocide® 3000, whose active ingredient is nano-needles of copper(II) hydroxide (nCu(OH)2). All leaves were treated at rates in accordance with the product label (1.5kgha−1 or 150mgm−2). As a control, we used highly soluble CuSO4. Over the course of the study (exposure up to 7 days followed by up to 20 days of elimination), hornworms accumulated Cu from all three treatments far exceeding controls (ranging from ~55 to 105 times greater for nCu(OH)2 and CuSO4 respectively). There were also significant differences in accumulation of Cu among treatments, with the greatest accumulation in the CuSO4 treatment (up to 105±18μg Cu per g dry mass) and the least in the nCu(OH)2 treatment (up to 55±12μg Cu per g dry mass. The difference in their toxicity and accumulation and elimination dynamics was found to be correlated with the solubility of the materials in the exposure suspensions (r2=0.99). We also found that first-instar larvae are more susceptible to toxicity from all forms of Cu than second-instar larvae. Our results provide valuable knowledge on whether the ecotoxicity of commercial MNM products such as Kocide can be compared with laboratory-synthesised counterparts and suggests that predictions can be made based on functional assays such as measurement of solubility.

The Role of Protons and Formation Cu(NH3)2+ During Ammonia-Assisted Solid-State Ion Exchange of Copper(I) Oxide into Zeolites

Solid-state ion exchange in mixtures of copper oxides and zeolites can occur at temperatures as low as 200–250 °C in the presence of ammonia (NH3-SSIE), thus providing a low-temperature method to activate zeolites for selective catalytic reduction nitrogen oxide (NH3-SCR). The ammonia induced solid-state ion exchange process is studied in more detail, by monitoring the development of NH3-SCR activity with duration of NH3-SSIE, formation of a mobile linear [Cu(NH3)2]+ complex with X-ray spectroscopy, and the transfer of Cu to the zeolite by XRD, and evaporation of copper(I)-oxide by TGA. We find that the linear [Cu(NH3)2]+ complex is formed in mixtures of copper-oxide and *BEA and CHA zeolites upon exposure to ammonia. Increasing the temperature for NH3-SSIE to well above 300 °C leads to a less efficient Cu-transfer. This indicates that the [Cu(NH3)2]+ complex is crucial for the NH3-SSIE process. The non-monotonous development of NOx conversion and N2O yield with duration of NH3-SSIE is probably due to an initial enrichment of Cu in the outer shell of the zeolite crystals. We also show that the presence of H+ or NH4+-ions in the zeolite are necessary for the NH3-SSIE, and that the transfer of Cu from the Cu-oxides to the zeolites most likely occurs via a surface diffusion process.

Contrasting sources and mobility of trace metals in recent sediments of western Lake Erie

Abstract Concentrations of the major and trace metals varied considerably in the western basin of Lake Erie, ranging from 0.9 to 25.3 mg/g for aluminum, from 2.9 to 36.5 mg/g for iron, from 6.4 to 74.8 mg/g for calcium, from 1.2 to 13.5 μg/g for cobalt, from 2.8 to 61.6 μg/g for copper, from 2.7 to 83.0 μg/g for lead, from 0.1 to 2.9 μg/g for cadmium, and from 7.1 to 127.3 μg/g for strontium. Distinct patterns of sediment metal variability allowed the identification of two major fluvial sources and some active in-lake biogeochemical processes. The inputs of Sr were largely from the Maumee River, the inputs of Cu, Pb, Cd, and Co were dominated by the Detroit River, and the inputs of Fe and Al were roughly evenly from the two rivers. The removal of Sr and Ca from the water column was mainly through coprecipitation with calcite. In contrast, the transfer of Cu, Pb, Cd, and Co was largely attributed to the removal of fine sediment particles from the Detroit River mouth and adjacent nearshore areas and the deposition of the metals scavenged by settling organic materials in the basin's central deeper areas. The mobility of the trace metals was different during the in-lake mass transfer, with Co being the most mobile and Cd being the least mobile. Furthermore, the trace metal mobility differences have decreased significantly during the past half-century due to a substantial increase in organic matter from eutrophication in the basin.

From soil to rice – a typical study of transfer and bioaccumulation of heavy metals in China

ABSTRACTFor the purpose of studying the contamination, bioaccumulation and transfer of heavy metals and understanding the effects of soil properties on these, the work was carried out on a regional scale. A total of 30 sets of soil and pairing rice tissues samples (root, straw and grain) were collected in Xiangzhou of Guangxi, China; soil properties and Cd, Cu, Pb and Zn of different rice tissues were analyzed. The mobility and bioaccumulation of Cd, Cu, Pb and Zn were assessed by transfer coefficients and bioaccumulation factors of them. The results indicated that the excess proportions of Cd and Pb were 50%, 3.33% and 30%, 6.67% in soil and rice grain, respectively, according to Chinese maximum permitted concentrations of heavy metals. Cd and Zn showed stronger bioaccumulation and mobility capability; the bioaccumulation and transfer of Cu were slightly lower than Cd and Zn; Pb had the weakest mobility. The bioaccumulation and mobility of heavy metals from soil to rice were restrained by soil pH, CaO, SOC, Fe oxides and Mn.

Copper bioaccumulation and biokinetic modeling in marine herbivorous fish Siganus oramin

Marine herbivorous fish directly consume macroalgae, which commonly accumulate high levels of trace metals in polluted areas. We proposed that herbivorous fish could be better candidates for biomonitoring marine metal pollution than carnivorous fish. To date, the trophic transfer of Cu from macroalgae to marine herbivorous fish is unclear. In this study, the kinetics of Cu bioaccumulation in a widespread marine herbivorous fish, Siganus oramin, were investigated, and biokinetic modeling was applied to estimate the Cu levels in the fish sampled from different sites and seasons. The results showed that Cu accumulation in the fish was linearly correlated to the dietary Cu levels in the different prey species, which were proportional to the waterborne Cu concentrations. The Cu found in the subcellular trophically available metal fraction (TAM) in the prey contributed the largest proportion of accumulated Cu in S. oramin. The dietary assimilation efficiencies (AEs) of Cu were 15.56 ± 1.76%, 13.42 ± 2.86%, and 21.36 ± 1.47% for Ulva lactuca, Gracilaria lemaneiformis and Gracilaria gigas, respectively. The calculated waterborne uptake rate constant (ku) of Cu was 0.023 ± 0.011 L g−1 d−1, and the efflux rate constant (ke) was 0.055 ± 0.021 d−1. Dietary Cu accounted for 60%–75% of the body Cu in S. oramin, suggesting that dietary uptake could be the primary route for Cu bioaccumulation in herbivorous fish. The biokinetic model demonstrated that the Cu concentrations in the water and fish presented a positive linear relationship, which was in line with our field investigation along the coastal areas of South China. Therefore, we suggested that S. oramin could be used as a biomonitoring organism for Cu pollution in the marine environment. However, the heterogeneities between the predicted levels and the measured levels of Cu implied that seasonal changes should be taken into account to improve the accuracy of the model.

Trophic transfer of Cu, Zn, Cd, and Cr, and biomarker response for food webs in Taihu Lake, China.

Water, sediments, and aquatic organism samples were collected from Taihu Lake in China. Four types of typical heavy metal (Cu, Zn, Cd, and Cr) were analyzed to evaluate their concentrations and trophic transfer in food webs. The stable nitrogen isotope δ15N was used to investigate the trophic interactions. The concentrations of Cd and Zn in the sediments of Taihu Lake exceeded Level I of the China National Quality Standards for Soil. Zn accumulation was identified to increase with the trophic level. The bioconcentration of the four heavy metals in aquatic organisms was evident, with the invertebrates showing the highest bioconcentration factor in the food webs. Several biomarkers were investigated, including metallothionein (MT), malondialdehyde, and Na+/K+-adenosine triphosphatase activity. A positive correlation relationship was found between the MT content and heavy metal accumulation in organism tissues.

Comproportionation Reaction of Cu(II)/Cu(0) in Ethaline-Water Mixed Solvents

The comproportionation reaction of Cu(II) + Cu(0) → 2Cu(I) in ethaline-water mixed solvents has been studied by means of different electrochemical techniques such as cyclic voltammetry, linear sweep voltammetry and chronopotentiometry. The cyclic voltammograms of Cu(II) show two couples of redox peaks in all mixtures, which demonstrate that the comproportionation reaction is thermodynamically favorable. In order to clarify the reaction kinetics of this heterogeneous reaction, the diffusion coefficient of Cu(II) and the rate constant of the reaction were estimated. Results show that the apparent reaction rate constant mainly depends on the diffusion of the Cu(II) species in all the mixtures. Thus, adding water into ethaline can enhance the mass transfer of Cu(II) species and increase the reaction rate.

In Situ Subcellular Imaging of Copper and Zinc in Contaminated Oysters Revealed by Nanoscale Secondary Ion Mass Spectrometry.

Determining the in situ localization of trace elements at high lateral resolution levels in the biological system is very challenging, but critical for our understanding of metal sequestration and detoxification. Here, the cellular and subcellular distributions of Cu and Zn in contaminated oysters of Crassostrea hongkongensis were for the first time mapped using nanoscale secondary ion mass spectrometry (nanoSIMS). Three types of metal-containing cells were revealed in the gill and mantle of oysters, including Cu-specific hemocytes, Cu and Zn-containing granular hemocytes, and Cu and Zn-containing calcium cells. Obvious intercellular distribution of Cu was found in the gill tissue, indicating the potential role of hemolymph in the transportation of Cu in oysters. The distribution of Cu showed a strong colocalization with sulfur and nitrogen in Cu-specific hemocyte and intercellular hemolymph. In the Cu and Zn-containing granular hemocytes and calcium cells, the co-occurrence of Cu and Zn with phosphorus and calcium was also found. Different relationships of distributions between Cu/Zn and macronutrient elements (nitrogen, sulfur and phosphorus) implied the differential metal complexation in oysters. Interestingly, quantitative analysis of the ratios of 32S-/12C14N- and 31P-/12C14N- of metal-deposited sites suggested the dynamic process of transfer of Cu and Zn from the metabolized protein pool to a more thermodynamically stable and detoxified form.

Heat and mass transfer effects of laser soldering on growth behavior of interfacial intermetallic compounds in Sn/Cu and Sn-3.5Ag0.5/Cu joints

The magnitudes of input power and scan speed of laser heat source can affect the morphology and size of interfacial Cu6Sn5 intermetallic compound (IMC) formed or grown in Sn/Cu and Sn-3.5Ag-0.5Cu/Cu (SAC/Cu) joints. Experimentally, it has been observed that greater power and smaller scan speed can create temperature field of higher magnitude, thereby enhancing the interfacial reaction. The occurrence of conglomerated, prismatic (faceted) and scalloped IMC morphologies in the specimens corresponding to designated laser processing parameters, has been explained with the help of Jackson parameter. The heat and mass transfer phenomena during laser soldering, is modeled using finite element analysis. Enthalpy method is applied in the FEM based computational model to describe the phase change based heat transfer at the melting regime of the solder. With an attainment of transient temperature profiles at several scan speeds through the numerical analysis, the values of interfacial reaction temperature at solder/substrate interface and diffusion phenomenon based mass transfer of Cu into solder are then utilized to explain the experimental results of IMC size. In comparison to pure Sn solder, SAC solder type is characterized with the formation of thicker IMC at laser power of 50W and scan speeds below 180mm/min.