Effect Of Copper Ions Research Articles

Effect of copper ions on the drainage stability of foams prepared from egg white

In this paper we investigate the effect of copper ions on the stability of foams prepared from egg white. We compare the time of formation and stability of foams prepared from fresh egg whites, with and without added copper ions. We find that the foams prepared with copper ions take more time to form, but are more stable. The effect increases upon dilution of the egg whites, which shows that the bulk phase is not responsible for the increase in stability. Microscopy shows that the initial bubble size distribution of the foam is not affected by the addition of copper ions. Measurements with a ring trough show that the surface tension of the liquid vapor interface of the foam films is also unaffected. The results of the ring trough measurements show that the increase in drainage stability is caused mainly by an increase in the surface dilatational elasticity of the interface. There is also an increase in the surface dilatational viscosity, but only at frequencies less than 0.1 Hz. The increase in the surface dilatational elasticity affects the drainage stability of the foam during the initial seconds of the drainage process, whereas the increase in the surface dilatational viscosity affects the long-term drainage stability.

Electrooptical Properties of Cells of the Soil Nitrogen-Fixing Bacterium Azospirillum brasilense: Effects of Copper Ions

The effects of copper ions on the uptake of some essential metals in the biomass and the electroop- tical properties of cell suspensions of the nitrogen-fixing soil bacterium Azospirillum brasilense sp. 245 were studied. Copper cations were shown to be effectively taken up by the cell biomass from the culture medium. The addition of copper ions increased the rate of uptake of some other metals present in the culture medium. This was accompanied by changes in the electrooptical characteristics of cell suspension as measured within the orienting electric field frequency range of 10 to 10000 kHz. The effects observed during short-term incuba- tion of A. brasilense in the presence of copper cations were less significant than during long-term incubation. These results can be used for the rapid screening of microbial cultures for the enhanced efficiency of sorption and the uptake of metals.

Effects of copper ions on the free radical-scavenging properties of reduced gluthathione: implications of a complex formation

The interaction between glutathione (GSH) and copper ions was investigated in vitro to determine whether such interaction could affect the free-radical scavenging properties of the tripeptide. To this end, the bleaching (decrease in OD734 nm) of a coloured solution containing the stable free-radical cation ABTS+, (which results from the addition of thiols to such a solution) was employed as an in vitro indication of the ability of the tripeptide to scavenge free radicals. While GSH bleached concentration-dependently (1.0-7.5 gM) the ABTS+-containing solution, its prior incubation (5 microM) in the presence of Cu+1 or Cu+2 ions (1-7.5 M) led to a metal concentration-dependent decrease of the bleaching capacity. At a ratio equal to one (5 microM each), the bleaching capacity of the copper plus GSH mixture was 50% of that seen for GSH alone. Further additions of copper (reaching ratios up to 2) did not result in greater decreases in the GSH-bleaching capacity. Noteworthy at the ratio of onewas that the copper plus GSH solutions maintained their bleaching capacity despite the lack of any DTNB-reactivity, i. e., the complete absence of thiols in the mixture. Mixtures of increasing concentrations of a fixed ratio (equal to 2) of copper plus GSH, which were found not to exhibit any DTNB-reactivity, showed a linear and concentration-dependent increase in bleaching capacity. The bleaching capacity remained unaltered when TRIEN, EDTA or histidine were added to pre-incubated (1:1) mixtures of copper plus GSH. However, the incubation of copper with TRIEN or EDTA (but not histidine) prior to GSH addition, totally prevented the loss of the original GSH-bleaching capacity. The present data supports the formation of a copper-glutathione complex which is stable to the presence of some copper-chelators, lacks all thiol reactivity, but fully conserves the free-radical scavenging properties of GSH.

Effects of Copper Ions on Thiol Compounds in the Liver of Carp

Effects of Copper Ions on Thiol Compounds in the Liver of Carp

Effect of Copper Ion on Conformations of Short Alanine-Based Peptides with Single TRP/HIS Stacking Interactions

Abstract: cu2+ has an apparent promoting effect on deaggregating β-sheet conformation, conformational transitions from β-sheet to α-helix, and enhancing α-helix conformation of short alanine-based peptides with single Trp/His (W/H) stacking interactions in different geometrical spacings and positions, respectively.

Interference of Copper Sulphate in Growth of Erwinia amylovora

AbstractTo understand the toxicity of copper salts on Erwinia amylovora, which are used in the control of fire blight, bacterial growth and cell metabolism was assayed with copper sulphate in the presence or absence of complex‐forming compounds such as various amino acids or citrate. In minimal medium without amino acids copper sulphate strongly interfered with the growth of E. amylovora. A concentration of 15 μm CuSO4 resulted in about 50% growth inhibition. In contrast to a strong effect of streptomycin, copper ions barely killed the cells when incubated in minimal medium for 1 h. The addition of 4 g asparagine per litre relieved a‘bacteriostatic’effect of copper ions and allowed growth of the bacteria at 2 mm CuSO4. Other amino acids had a similar effect in the protection of E. amylovora against copper ions. This was in contrast to glycine betain, which was unable to suppress growth inhibition by CuSO4. Presumably, the free ammonium groups of amino acids participated in the protective effect. The addition of citrate, exceeding the amount of copper‐ions, was also protective. Bioluminescence of E. amylovora cells was expressed via a constitutive promoter from the lux‐operon of Vibrio fischeri. The light emission is dependent on active cell metabolism. In a novel approach to determine the immediate response of E. amylovora after the addition of copper sulphate, the change of bioluminescence was determined. Addition of copper ions to MM3 medium strongly affected the bioluminescence, but no change in light production was noticed, when citrate or asparagine were present in addition to copper sulphate. A decrease of bioluminescence to 50% was observed for 50 μm CuSO4 in the absence of amino acids.

The mechanism of Bodian's silver staining: effect of copper ion on silver impregnation

We studied the effect of the duration (0.5–48 h) of silver impregnation on the intensity of Bodian's silver staining using formalin-fixed, paraffin-embedded sections of a human brain. The silver ion (Ag +) and copper ion (Cu 2+) in the silver protein solution were quantified simultaneously for treatments of various durations. Both the intensity of staining and the quantities of Ag + and Cu 2+ were greatly affected by the duration of silver impregnation. While the quantity of Ag + considerably decreased during the first 4 h of impregnation, that of Cu 2+ greatly increased. Only small changes were observed in both ions after 12 h. Neurofibrils or axons, and neurofibrillary tangles (NFTs) were clearly stained after 12–14 and 16–48 h of impregnation, respectively. Strong staining of these components was not observed for other durations of treatment. The amount of metallic copper in silver impregnation also affected both the intensity of staining and the quantities of Ag + and Cu 2+ in the silver protein solution. Ag + and Cu 2+ were also present in the gold trichloride acid solution in which the section was toned. These findings suggest that both Cu 2+ derived from metallic copper and silver protein are deposited on sections during silver impregnation, that the amount of Cu 2+ may determine the amount of silver protein deposited on the section, and that the reduced (metallic) form of silver and copper on the section may participate in gold toning. Thus, to achieve strong staining of a desired component, it is important to examine the conditions of silver impregnation (i.e. duration and amount of metallic copper). For strong staining of neurofibrils, axons and NFTs, optimal results are obtained by the addition of 5 g of metallic copper foil to 100 ml of 1% silver protein solution, and by 16–24 h of impregnation.

The high temperature corrosion of a low alloy steel in aqueous sodium chloride

The corrosion behavior of a low alloy steel (Fe-2.25 Cr-1 Mo) was investigated in 1 m NaCl over a range of high temperatures with various levels of contamination with CuCl 2. The net weight loss of the alloy and the weight of the corrosion product film on the alloy surface were measured over exposure times up to 480 h, and a temperature range of 75–250 °C. The corroded surfaces and the corrosion products were characterized using stereoscopic examination, SEM and X-ray diffraction (XRD). Sigmoidal shaped relations were obtained between the film weight and exposure time at several temperatures, suggesting a mechanism of lateral growth of the corrosion product film. This was confirmed by metallographic observations. Under some conditions, parabolic film growth was observed indicating diffusion control on the rate of corrosion. In all cases, a clear inflection was observed in the film weight-time relation at a certain transition time, the magnitude of which decreases with the temperature of the test. The alloy surface underwent pitting corrosion, to an extent dependent on the temperature and the concentration of CuCl 2. The pits exhibited a lace-like morphology similar to that reported previously at ambient temperatures. The presence of CuCl 2 in the corrosive medium leads to extensive detachment of the corrosion product off the corroding surface. Under these conditions, the spalled corrosion product was much more enriched with metallic copper than the corroding surface. This points to the serious effects of copper ions on the integrity and protection efficiency of the resulting corrosion product film.

Regulation of bacterial methane oxidation: transcription of the soluble methane mono-oxygenase operon of Methylococcus capsulatus (Bath) is repressed by copper ions.

Methane is oxidized to methanol by the enzyme methane mono-oxygenase (MMO) in methanotrophic bacteria. In previous work, this multicomponent enzyme system has been extensively characterized at the biochemical and molecular level. Copper ions have been shown to irreversibly inhibit MMO activity in vivo and in vitro, but the effect of copper ions on transcription of the genes encoding the soluble (cytoplasmic) MMO (sMMO) has not previously been investigated. To examine more closely the regulation of bacterial methane oxidation and to determine the role of copper in this process, we have investigated transcriptional regulation of the sMMO gene cluster in the methanotrophic bacterium Methylococcus capsulatus (Bath). Using Northern blot analysis and primer extension experiments, it was shown that the six ORFs of the sMMO gene cluster are organized as an operon and the transcripts produced upon expression of this operon have been identified. The synthesis of these transcripts was under control of a single copper-regulated promoter, which is as yet not precisely defined.

Effect of copper ion on the motility, viability, acrosome reaction and fertilizing capacity of human spermatozoa in vitro.

The objective of this study is to provide additional information on the effect of copper ion (Cu2+) in preventing pregnancy. Human spermatozoa, selected by the swim-up method, were incubated for 0, 5 or 24 h in the presence of 10 ng, 1 microgram, 10 micrograms or 100 micrograms of Cu2+ mL-1 in BWW culture medium, and then evaluated in terms of their motility, viability, acrosome reaction (AR) and the capacity to penetrate zona-free hamster eggs. AR and penetration in zona-free hamster eggs were assessed at 5 h of incubation. Motility, viability and AR in sperm incubated for 5 h were significantly affected by Cu2+ at a concentration of 100 micrograms mL-1, but not at the lower concentrations. Incubation for 24 h did not affect motility and viability of sperm incubated in the presence of concentrations of Cu2+ ranging from 10 ng mL-1 to 10 micrograms mL-1, but a concentration of 100 micrograms mL-1 caused a significant decrease in both parameters. In contrast, the penetration rate of zona-free hamster oocytes significantly decreased compared with that of controls, when only sperm were incubated in the presence of concentrations of Cu2+ ranging from 10 ng mL-1 to 10 micrograms mL-1, and no penetration was observed in the presence of 100 micrograms mL-1 of Cu2+ . When only oocytes were exposed to Cu2+, the penetration rate dropped to 50% of that of the controls. Finally, when both gametes were exposed to Cu2+ before co-incubation, the penetration rate fell to zero for every concentration tested. Results showed that copper, at concentrations similar to those released from intrauterine devices (IUD), affects the fertilizing capacity of human gametes in vitro and interferes with the sperm-oocyte interaction leading to fertilization. These effects suggest that the principle action of Cu2+ released from Cu-IUD is to act as a preconception contraceptive agent when delivered in endometrial and oviducal fluids.

りん酸による銅の電解研磨における銅イオンの影響

りん酸による銅の電解研磨における銅イオンの影響

Effect of heat-treated ceruloplasmin on the hepatic xanthine oxidase activity and type conversion

The effect of ceruloplasmin or copper ion on hepatic xanthine oxidase activity and type conversion was investigated using rat liverin vitro. It was observed that ceruloplasmin increased xanthine oxidase type conversion depending on duration of its storage. Xanthine oxidase (type O) activity and type conversion in incubation mixture was increased by the addition of heated celuroplasmin in a temperature dependent manner. The type conversion of xanthine oxidase induced by heated ceruloplasmin was retumed to normal by the treatment with DTT or penicillamine. The effect of copper ion on type conversion of xanthine oxidase was similar to that of heated ceruloplasmin.

Exogenously added copper does not increase the production of copper amine oxidase in lentil seedlings

The effect of copper ions, the inorganic cofactor of amine oxidase (AO; EC 1.4.3.6), on the production of this enzyme in lentil ( Lens culinaris) seedlings was studied. The addition of CuSO 4 to the imbibition water during the germination of lentils increased the AO activity. However, the amounts of specific mRNA and protein were not affected by the presence of Cu 2+. Furthermore, the addition of Cu 2+ to homogenates of lentil seedlings grown in the absence of the metal substantially increased the AO activity. Therefore, it appears that exogenously added Cu 2+ does not increase the production of AO in lentil seedlings which are still able to synthesize the copper-free enzyme. The addition of Cu 2+ seems to reconstitute the enzymatically active holoprotein.

Effect of Copper Ions in the Slurry on the Chemical‐Mechanical Polish Rate of Titanium

Titanium is being investigated as the adhesion promoter and diffusion barrier between silicon dioxide and copper in a copper metallization scheme. Chemical‐mechanical polishing (CMP) is being used to define the inlaid copper interconnections. An investigation into the CMP of titanium has revealed an interaction between the presence of copper ions in the polish slurry and the polish rate of titanium. The polish rate of titanium increases dramatically when copper ions are present in the slurry from the previous copper polish step. In this paper, we present and discuss the results of these investigations.

Chemical Behavior of Radioiodine in Boiling Water Reactor Systems II: Effects of Hydrogen Water Chemistry

The investigation of the chemistry and steam transport behavior of radioiodine in boiling water reactors has been extended to four more reactors during fullscale hydrogen water chemistry (HWC) tests. Under the reducing coolant chemistry environment, most of the radioiodine was found in the iodide (I-) form. The iodine steam carryover was found to increase in varying degree under HWC conditions in two reactors and was practically unchanged in the other two reactors. The variations in radioiodine chemical forms and steam carryover are discussed in terms of radiolytic reactions, and the effect of copper ions in the reactor water is qualitatively evaluated. The effect of HWC on radioiodine transport is not significant.

Madelung potentials and valences in the Y 1Ba 2Cu 3O 7 superconductor

Using Ewald's method, we calculated the ion-site potentials and Madelung energy of Y 1Ba 2Cu 3O 7 (orthorhombic, Pmmm, No. 47). We considered the effects of copper-ion and oxygen-ion valences. Among seven suggested copper-oxygen ion-charge configurations, only two give a low electrostatic bonding energy to agree with oxygen vacancies on O( 1 ) sites. Only one configuration gives a realistic bulk modulus. We perturbed this configuration by equalizing the Cu( 1 )-Cu( 2 ) valences and introducing a hole into the CuO 2 plane at the oxygen sites. This configuration also agrees well with observation.

The effect of copper ions on galena floatability and ethyl xanthate adsorption

The effect of different concentrations of dissolved copper ions on floatability and potassium ethyl xanthate (KEX) adsorption on galena were examined in the pH range from 6.0 to 10.0. The flotation tests and zeta-potential measurements under various conditions of reagent concentrations and pH were carried out and correlated with the results of infrared attenuated total reflection spectroscopy (ATR-IR) of surface changes. Copper from the solution significantly reduced the collectorless flotation of galena in the pH range from 6.5 to 9.5. However, collection with KEX provided a good floatability of galena. Although the treatment with copper ions depressed the collectorless galena flotation, it had an activating effect on galena flotation with KEX as a collector. An even better flotation was accomplished when galena was treated with copper (II) sulphate than without treatment, after collection with KEX of the same concentrations. Infrared data always indicated the presence of both Pb xanthate and Cu(I) xanthate on galena surfaces after treatments with copper (II) sulphate. The proportions of monolayer or multilayer forms of Pb xanthate, as well as Cu (I) xanthate, were different and dependent on the reagent concentration and pH conditions in the adsorption experiments. The mechanism of KEX adsorption on copper sites on galena surfaces depended on the pH.

Purification of an ammoniacal zinc leach liquor using a rotating zinc disc after copper solvent extraction

A process for purifying an ammoniacal complex sulphide leach liquor through a cementation route using pure zinc is described. Purification of the leach liquor is mandatory in order to improve the quality of electrowon zinc. The cementation studies were carried out using a rotating zinc disc. Various parameters such as rotation speed and the effect of copper ion vis-à-vis the cementation of cadmium, cobalt and nickel were studied. The presence of copper gives a marked improvement in the cementation of cobalt and nickel whereas cadmium cementation shows a negative trend. With an increase of rotation speed of the zinc disc, the rate of cementation becomes faster. Initially the cementation rate is faster and with time the rate falls off. The cementation of cadmium is much faster than that of cobalt and nickel.

Effect of copper ions on the crystallization of bayer aluminium trihydroxide

The effect of copper ions on the crystallization of Bayer aluminium trihydroxide has been examined using the SEM/EDAX technique and particle size analyses. The presence of copper ions, presumably stabilised in solution as the cuprate(II) ion, disrupts the normal crystal growth process and induces secondary nucleation on the aluminium trihydroxide seed crystal surfaces. Although the copper ions adsorb preferentially on the (001) seed crystal surfaces, most of the new crystal formation occurs on the prismatic faces of the pseudo-hexagonal seed crystals. The roughened seed crystal surfaces and the tiny crystalline protrusions promote agglomeration of the seed crystals during subsequent crystallization.

Effect of copper ion on the formation of .ALPHA.-form crystal in silk crystalline part.

Effect of copper ion on the formation of .ALPHA.-form crystal in silk crystalline part.