INFRARED SPECTRA AND CRYSTAL STRUCTURE OF BIS-(DIMETHOXYLPHOSPHATO) COPPER

The title complex has beep synthesized by the reaction of CaCl2, with trimethyl phosphate. Its Infrared spectra from 4000 to 100 cm(-1) measured. The assignment of acme absorption bands was discussed. It is found that the stretching vibrations of bridge groups O-P-O are divided into two groups according to their bond length. The crystal structure of the complex boa been determined from single crystal K-ray diffraction data. The crystals belong to monoclinic system, space group P2(1)/c with cell parameteras, a = 1,0704(4), b = 0.5093(2), c = 1.9737(6)nm, beta = 96.23(3)degrees, V = 1.0696(6)nm(2), Z = 4, final R = 0.044. Copper ion is coordinated to five Rimester oxygen atoms to form a distorted square pyramid. The adjacent copper ions are connected by symmetric and non-symmetric bridge groups of O-P-O, forming an infinite one-dimensional chain coordination polymer.

CYCLIC VOLTAMMETRIC AND SPECTROELECTROCHEMICAL STUDIES OF COPPER IN ALKALINE-SOLUTION

The behaviour of the electroplated copper film electrode on tin oxide/glass or glassy carbon surface was studied in potassium hydroxide medium by cyclic voltammetry and in situ transmission spectroelectrochemistry. The results indicate that the electroplated copper film electrode is similar to a copper electrode and cyclic voltammetry with this electrode affords more resolution. The anodic peaks were found to correspond successively to the adsorption of oxygen, the formation of a surface layer of Cu2O, the formation of a surface layer of Cu(OH)2 or CuO and formation of a thick multilayer film of CuO. This is the first time it has been proposed that a surface layer of Cu(OH)2 or CuO is formed from the oxidation of the surface layer of Cu2O. Similarly, a clear interpretation is presented that the cathodic peaks correspond successively to the reduction of CuO to Cu2O, the reductions of Cu2O to Cu and the soluble Cu(II) species to Cu. On the other hand, a shoulder peak related to the chemical transformation of Cu(OH)2 to CuO was first observed.

LIQUID-CHROMATOGRAPHY AMPEROMETRIC DETECTION OF CARBOXYLIC-ACIDS AND PHENOLIC-ACIDS WITH A COPPER-BASED CHEMICALLY-MODIFIED ELECTRODE

A copper-based chemically-modified electrode has been constructed and characterized by various experimental parameters in flow-through amperometric detection of carboxylic acids and phenolic acids. Novel hydrodynamic voltamperograms were first obtained in flow-through amperometric detection with the Cu-based CME and subsequently negative and positive peaks were observed in a single chromatogram. This unique and flexible potential dependence could be of great benefit in chromatographic speciation and quantification. These observations suggest that the detector response was governed by the complexation reaction of copper ions with the solutes.

Analysis of the effect of copper on the virulence of a pathogenic Edwardsiella tarda strain

Aim: To investigate the effect of copper on the virulence of Edwardsiella tarda. Methods and Results: The pathogenic Edw. tarda strain TX5 was cultured under copper-stressed conditions and examined for any potential alteration in capacities that are associated with pathogenicity. The results showed that compared to untreated TX5, Cu-treated TX5 exhibits reduced planktonic and biofilm growth, an impaired ability to adhere to host mucus, modulation of host immune response, and dissemination in host blood and liver. Consistent with these observations, the overall bacterial virulence of Cu-treated TX5 is significantly attenuated. SDS-PAGE analyses of whole cell protein production showed that Cu-treated TX5 differs from the untreated TX5 in its production of at least one protein. Quantitative real time reverse transcriptase PCR analyses showed that copper treatment decreased the expression of virulence-associated genes encoding components of the type III and type VI secretion systems, the Eth haemolysin system, and the LuxS/AI-2 quorum-sensing system. Conclusions: Prolonged exposure to copper has multiple effects on TX5 and results in significant attenuation of bacterial virulence. Significance and Impact of the Study: The results of this study demonstrate that copper treatment has a broad and profound effect on the virulence-associated capacities of TX5, which is exerted at least in part at the transcription level. These findings provide new insights to the antimicrobial mechanism of copper.

Molecular analysis of the copper-responsive CopRSCD of a pathogenic Pseudomonas fluorescens strain

CopRS/CopABCD is one of the known systems that control copper homeostasis in bacteria. Although CopRS/CopABCD homologues are found to exist in Pseudomonas fluorescens, the potential role of this system in P. fluorescens has not been investigated. In this study a genetic cluster, consisting of copR, S, C, and D but lacking copAB, was identified in a pathogenic P. fluorescens strain (TSS) isolated from diseased fish. The copRSCD cluster was demonstrated to be required for full copper resistance and regulated at the transcription level by Cu. Expression of copCD is regulated directly by the two-component response regulator CopR, which also regulates its own expression. Interruption of the regulated expression of copR affected bacterial growth, biofilm formation, and tissue dissemination and survival. A mutant CopR, which lacks the N-terminal signal receiver domain and is constitutively active, was found to have an attenuating effect on bacterial virulence when expressed in TSS. To our knowledge, this is the first report that suggests a link between CopR and bacterial pathogenicity in P. fluorescens.

Simultaneous determination of four phases of copper in geological samples

According to the specific property of respective phases in copper ore, optimal extracting condition for, tour phases of copper with five infusion was examined. After a series of experiments, for example, different weight Of sample, artificial mixed single phases sample and repeated experiment, the extracting ratio constants foil all phases in different infusions were obtained. The mathematical model which is on the basis of the stable extracting constant is established. Based on the purpose-control genetic algorithms, we only need to determine the total copper in the sample in different infusions under the selected condition, then the value of respective phase could be calculated. The-relative standard deviation are (%) free oxidized copper phase:1.5, conjunction oxidized copper phase: 17.6,, secondary copper sulfide phase: 1.9, primary copper sulfide phase : 2.7,total copper: 0.8.

Distribution and mobility of metals in agricultural soils near a copper smelter in South China

The distribution and mobility of heavy metals in the paddy soils surrounding a copper smelting plant in south China was investigated. We assessed the degree of metal contamination using an index of geoaccumulation. The metals were divided into two groups: (1) Cu, Zn, Pb and Cd, whose concentrations were heavily affected by anthropogenic inputs, and (2) Ni, Co and Cr, which were mainly of geochemical origin. Concentrations of Cu, Cd, Zn, and Pb in the polluted soils were higher than the Chinese soil quality criteria. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the residual and NH2OH HCl extractable fractions. In contrast, Cd was predominantly associated with the MgCl2 extractable fraction. A large proportion of Cu was bound to the acidic H2O2 extractable fractions, while Zn was predominantly found in the residual phase. The fraction of mobile species, which potentially is the most harmful to the environment, was found to be elevated compared to unpolluted soils in which heavy metals are more strongly bound to the matrix. The mobility of the metals was studied by water extraction using a modification of Tessier's procedure, and the order of mobility was Zn > Cd > Cu > Ce > Pb.

Cloning, characterization, and expression analysis of extracellular copper/zinc superoxide dismutase gene from bay scallop Argopecten irradians

Extracellular superoxide dismutase (ECSOD) is a major extracellular antioxidant enzyme that protects organs from damage by reactive oxygen species (ROS). We cloned a novel ECSOD from the bay scallop Argopecten irradians (AiECSOD) by 3' and 5' RACE. The full-length cDNA of AiECSOD was 893 bp with a 657 bp open reading frame encoding 218 amino acids. The deduced amino acid sequence contained a putative signal peptide of 20 amino acids, and sequence comparison showed that AiECSOD had low degree of homology to ECSODs of other organisms. The genomic length of the AiECSOD gene was about 5276 bp containing five exons and six introns. The promoter region contained many putative transcription factor binding sites such as c-Myb, Oct-1, Sp1, Kruppel-like, c-ETS, NF kappa B, GATA-1, AP-1, and Ubx binding sites. Furthermore, tissue-specific expressions of AiECSOD and temporal expressions of AiECSOD in haemocytes of bay scallops challenged with bacteria Vibrio anguillarum were quantified using qRT-PCR. High levels of expression were detected in haemocytes, but not in gonad and mantle. The expression of AiECSOD reached the highest level at 12 h post-injection with V. anguillarum and then returned to normal between 24 h and 48 h post-injection. These results indicated that AiECSOD was an inducible protein and that it may play an important role in the immune responses against V anguillarum. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.

Intracellular copper/zinc superoxide dismutase from bay scallop Argopecten irradians: Its gene structure, mRNA expression and recombinant protein

Superoxide dismutases are an ubiquitous family of enzymes that function to efficiently catalyze the dismutation of superoxide anions. Two unique and highly compartmentalized bay scallop Argopecten irradians superoxide dismutases: MnSOD and ecCuZnSOD, have been molecularly characterized in our previous study. To complete characterize the SOD family in A. irradians, a novel intracellular copper/zinc SOD from the A. irradians (Ai-icCuZnSOD) was obtained and characterized. The full-length cDNA of Ai-icCuZnSOD was 1047 bp with a 459 bp open reading frame encoding 152 amino acids. The genomic length of the Ai-icCuZnSOD gene was about 4279 bp containing 4 exons and 3 introns. The promoter region containing many putative transcription factor binding sites were analyzed. Furthermore, quantitative reverse transcriptase real-time PCR (qRT-PCR) analysis indicated that the highest expression of the Ai-icCuZnSOD was detected in gill and the expression profiles in hemocytes of bay scallops challenged with bacteria Vibrio anguillarum and lipopolysaccharide (LPS) were different. The result presented an increased expression after injection with LPS whereas no significant changes were observed after V. anguillarum injection. A fusion protein containing Ai-icCuZnSOD was produced in vitro. The rAi-icCuZnSOD is a stable enzyme, retaining more than 80% of its activity between 10 and 60 degrees C and keeping above 88% of its activity at pH values between 5.8 and 9. Ai-icCuZnSOD is more stable under alkaline than acidic conditions. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

Biosorption of copper(II) from aqueous solutions by green alga Cladophora fascicularis

Biosorption is an effective means of removal of heavy metals from wastewater. In this work the biosorption behavior of Cladophora fascicularis was investigated as a function of pH, amount of biosorbent, initial Cu2+ concentration, temperature, and co-existing ions. Adsorption equilibria were well described by Langmuir isotherm models. The enthalpy change for the biosorption process was found to be 6.86 kJ mol(-1) by use of the Langmuir constant b. The biosorption process was found to be rapid in the first 30 min. The presence of co-existing cations such as Na+, K+, Mg2+, and Ca2+ and anions such as chloride, nitrate, sulfate, and acetate did not significantly affect uptake of Cu2+ whereas EDTA substantially affected adsorption of the metal. When experiments were performed with different desorbents the results indicated that EDTA was an efficient desorbent for the recovery of Cu2+ from biomass. IR spectral analysis suggested amido or hydroxy, C=O, and C-O could combine strongly with Cu2+.

Biosorption of copper (II) and lead (II) from aqueous solutions by nonliving green algae Cladophora fascicularis: Equilibrium, kinetics and environmental effects

Biosorption of Cu2+ and Pb2+ by Cladophora fascicularis was investigated as a function of initial pH, initial heavy metal concentrations, temperature and other co-existing ions. Adsorption equilibriums were well described by Langmuir and Freundlich isotherm models. The maximum adsorption capacities were 1.61 mmol/ g for Cu2+ and 0.96 mmol/ g for Pb2+ at 298K and pH 5.0. The adsorption processes were endothermic and biosorption heats calculated by the Langmuir constant b were 39.0 and 29.6 kJ/ mol for Cu2+ and Pb2+, respectively. The biosorption kinetics followed the pseudo- second order model. No significant effect on the uptake of Cu2+ and Pb2+ by co-existing cations and anions was observed, except EDTA. Desorption experiments indicated that Na(2)EDTA was an efficient desorbent for the recovery of Cu2+ and Pb2+ from biomass. The results showed that Cladophora fascicularis was an effective and economical biosorbent material for the removal and recovery of heavy metal ions from wastewater.

Preparation of Dendritic Copper Nanostructures and Their Characterization for Electroreduction

Dendritic copper nanostructures of different morphologies were synthesized by a surfactant-free electrochemical method. Single crystal nature of the nanostructures was revealed from their X-ray diffraction and electron diffraction patterns. Mechanism of dendrite formation was discussed from thermodynamic aspects using the concept of supersaturation. Supersaturation of the copper metal reduced on the surface of the electrode was the crucial factor for the generation of different morphologies. Effects of applied potential, temperature, and the solution concentration on the supersaturation were studied. The NO3- and H2O2 electroreduction ability of the dendritic materials was tested. Use of copper dendrite-modified electrode as NO3- sensor was demonstrated.