Biofouling, especially microfouling, is a major concern with the use of titanium (Ti) in the marine environment as a condenser material in cooling water systems. Earlier, copper-nickel (Cu/Ni) alloys were extensively used in marine environments due to their high corrosion and biofouling resistance. However, the choice of condenser material for the new fast breeder reactor in Kalpakkam is Ti to avoid steam side corrosion problems, which may pose a threat to steam generator parts having sodium as the secondary coolant. This study evaluates the surface modification of Ti using nano films of copper (Cu) and nickel (Ni) to utilize the antibacterial property of copper ions in reducing microfouling. The surface modification of Ti was carried out by the deposition of a Cu/Ni bilayer and (Cu/Ni)10 ...

Synthesis of seven new indolenyl sulfonamides, have been prepared by the condensation reaction of indole-3-carboxaldehyde with different sulfonamides such as, sulphanilamide, sulfaguanidine, sulfathiazole, sulfamethoxazole, sulfisoxazole, sulfadiazine and sulfamethazine. These synthesized compounds have been used as potential ligands for complexation with some selective divalent transition metal ions (cobalt, copper, nickel & zinc). Structure of the synthesized ligands has been deduced from their physical, analytical (elemental analyses) and spectral (IR, 1H NMR and 13C NMR & UV-vis) data. All the compounds have also been assayed for their in vitro antibacterial and antifungal activities examining six species of pathogenic bacteria (Escherichia coli, Shigella flexneri, Pseudomonas aerugino...

Synthesis of seven new indolenyl sulfonamides, have been prepared by the condensation reaction of indole-3-carboxaldehyde with different sulfonamides such as, sulphanilamide, sulfaguanidine, sulfathiazole, sulfamethoxazole, sulfisoxazole, sulfadiazine and sulfamethazine. These synthesized compounds have been used as potential ligands for complexation with some selective divalent transition metal ions (cobalt, copper, nickel & zinc). Structure of the synthesized ligands has been deduced from their physical, analytical (elemental analyses) and spectral (IR, (1)H NMR and (13)C NMR & UV-vis) data. All the compounds have also been assayed for their in vitro antibacterial and antifungal activities examining six species of pathogenic bacteria (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis) and six of fungi (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium soloni and Candida glabrata). Antibacterial and antifungal results showed that all the compounds showed significant antibacterial activity whereas most of the compounds displayed good antifungal activity. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina. PMID:20005022

Lentinan, a mushroom polysaccharide, isolated from Lentinus edodes (Shiitake mushroom) was sulfated in dimethylsulfoxide to obtain a water-soluble derivative coded as LS. Then, two polysaccharide-based polyelectrolytes, polyanionic lentinan sulfate (LS) and polycationic chitosan (CS), were alternatively deposited onto the surfaces of polyurethane (PU) via layer-by-layer (LbL) assembly technique. The surfaces modified by polysaccharide-based multilayers were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurements. The fibrinogen adsorption and platelet adhesion to the surfaces, cytocompatibility to L-929 cells, and antibacterial activity against Pseudomonas aeruginosa of unmodified PU and LbL-modified PU were tested in vitro, respectively. The results showed that the water contact angle decreased gradually during the successive buildup of the polysaccharide-based multilayers, and decreased slowly after four bilayers were assembled. The surface roughness of PU modified by five bilayers (LS as topmost layer) increased compared with that of unmodified PU. The fibrinogen adsorption on the surface decreased 81% after assembly of five bilayers (LS as topmost layer). The number of adherent platelets on the surface modified by five bilayers (LS as topmost layer) is reduced, in comparison with that of the unmodified PU. The tests of L-929 cells indicated that LbL-modified PU surfaces had better cytocompatibility than unmodified PU. In addition, PU modified by polysaccharide-based multilayers showed antibacterial activity against P. aeruginosa. PMID:22771524

for the Accommodation of Magnetic Spectrometer Payload on Spacelab ...... A copper-nickel matrix composite wire has been chosen to provide the high normal -state .... Bs inside that material (typically 10 to 20 kilogauss-for soft iron). A ...

denum disulfide to sputter cleaned surfaces of copper, nickel, gold, and 304 stainless steel. Pin on disk ... Transfer is not uniform and large particles will transfer when ..... Adhesion of MoS2 Powder Burnished on Metal Substrates. J. Vac. Sci.

and solutions studied for cffcets on ordi- nary construction ... anct is attainable in the titanium-bonn allop and that the ..... liquid and vapor phases of chloride bear- ing boiler ... Hastelloy, 70-30 copper-nickel, Strlliter, and Dunniikd ull~y others.

Aug 2, 1983 ... ide (InSb), cadmium telluride (CdTe), and zinc sulfide. (ZnS). Referring ... copper, nickel, chromium and mixtures and alloys of the .... Electroless plating re- quires no ... ally conductive precipitate insoluable in both solutions ...

A model of nucleation and growth of the copper-nickel precipitates in pressure vessel steels of VVER reactors under irradiation is constructed. The contribution of these precipitates to radiation embrittlement of thermal-neutron reactors is analyzed.

Pute Elements: Gold, Silver, Copper, Nickel, Cobalt, Iron, Iridium, Indium, Palladium, ... Ruthenium”, Bismuth, Tin, Lead, Antimony, Zinc, Tellurium among others. ... consists of a high-purity, neutron transmutation doped (NTD), single crystal Ge ...

A method of analysis of yttrium metal and yttrium oxide for the determination of trace amounts of copper, nickel, iron, and molybdenum is reported. These impurities were separated from yttrium by liquid-liquid extraction. No difficulties were encountered in the determination of copper, nickel, or iron. Some difficulty was experienced in the determination of molybdenum when large quantities of copper also were present. Several washings were necessary to clear up the turbidity caused by the precipitation of the copper as cuprous thiocyanate. (auth)

A solid phase extraction method has been developed for the determination of copper, nickel and zinc ions in natural water samples. This method is based on the adsorption of copper, nickel and zinc on multiwalled carbon nanotubes (MWCNTs) impregnated with di-(2-ethyl hexyl phosphoric acid) (D2EHPA) and tri-n-octyl phosphine oxide (TOPO). The influence of parameters such as pH of the aqueous solution, amount of adsorbent, flow rates of the sample and eluent, matrix effects and D2EHPA-TOPO concentration have been investigated. Desorption studies have been carried out with 2 mol L(-1) HNO(3). The copper, nickel and zinc concentrations were determined by flame atomic absorption spectrometry. The results indicated that the maximum adsorption of copper, nickel and zinc is at pH 5.0 with 500 mg of MWCNTs. The detection limits by three sigma were 50 ?g L(-1) for copper, 40 ?g L(-1) for nickel and 60 ?g L(-1) zinc. The highest enrichment factors were found to be 25. The adsorption capacity of MWCNTs-D2EHPA-TOPO was found to be 4.90 mg g(-1) for copper, 4.78 mg g(-1) for nickel and 4.82 mg g(-1) for zinc. The developed method was applied for the determination of copper, nickel and zinc in electroplating wastewater and real water sample with satisfactory results (R.S.D.'s <10%). PMID:21041024

Copper, nickel and copper?nickel nanoparticles were prepared by solution combustion method for use in direct write printing. Structural (X-ray diffraction) and morphological (transmission electron microscope) investigations showed that pure metal (Cu and Ni) and CuNi alloy particles with face-centred cubic crystal structure were formed. Atomic absorption spectrometer studies confirmed that the nanoparticle compositions corresponded to the initial Cu/Ni molar ratios selected for synthesis. Particle size and morphology were significantly influenced by composition, with high Cu content coinciding with small, spherical particles as opposed to larger, irregular shapes observed at high Ni concentrations. X-ray photoelectron spectroscopy measurements revealed that after the reduction process the ...

The objectives of the program were to evaluate the effect of counterbore on the fatigue behavior of butt-welded, consumable-insert joints in 4-inch-diameter, Schedule 40, carbon-steel and copper-nickel piping and the effect of as-welded surface, with and ...

Superconducting niobium coatings have been electrodeposited from molten salts onto titanium substrates with a copper, nickel, or molybdenum protective layer, and their structure and magnetic properties have been studied. The coatings are shown to be suitable as a starting material for the superconducting layer of the rotor of cryogenic gyroscopes.

...resemble insect larvae. This reproductive...organisms for toxicity testing purposes...criteria for copper, nickel...than this acute value. Nickel...spinymussel mussel larvae also require...addressing the acute thermal tolerance...sensitivity to copper in juveniles...exposed to copper were less...thereby the toxicity) of...

The results of an investigation conducted to determine the corrosion characteristics of a number of alloys in a high saline environment are discussed. The ferritic stainless steels and several copper/nickel alloys exhibited good corrosion resistance in these high saline geothermal environments.

The aim of this work was to seek an environmentally friendly process for recycling metals from biomass-sludges generated in the treatment of industrial wastewaters. This work proposes a hybrid process for selective recovery of copper, nickel and zinc from contaminated biomass of Saccharomyces cerevi...

The outlook for mining in Indonesia is presented. Coal appears to be the most promising growth area for Indonesian mining interests, with production slated to reach 1.5 million t/yr by 1985, up from 0.5 million ton in 1983. Also discussed production and trends, aluminum, copper, nickel, silver, gold, tin and iron sands in Indonesia.

Membrane proteins, which are the target of most drugs, are implicated in many critical cellular functions such as signal transduction, bioelectricity, exocytosis and endocytosis. Therefore, developing techniques to investigate the functions of membrane proteins is obviously important. Here, we have developed a novel system by integrating artificial lipid bilayer (biomimetic membrane) with single-walled carbon nanotube networks (SWNT-net) based field-effect transistor (FET), and demonstrated that such hybrid nanoelectronic biosensors can specifically and electronically detect the presence and dynamic activities of ionophores (specifically, gramicidin and calcimycin) in their native lipid environment. This technique can potentially be used to examine other membrane proteins (e.g. ligand-gated ion channels, receptors, membrane insertion toxins, and antibacterial peptides) for the purposes of biosensing, fundamental studies, or high throughput drug screening. PMID:20047826

Piscidin 1 (Pis-1) has a high broad-spectrum activity against bacteria, fungi, and viruses but it also has a moderate hemolytic activities. To improve the antibacterial activity and to reduce toxicity, mutants Pis-1AA (G8A/G13A double mutant) and Pis-1PG (G8P mutant) have been designed based on the crystal structure of Pis-1. Eighteen independent molecular dynamics (MD) simulations of Pis-1 and its mutants with membranes are conducted in this article. Furthermore, 60 independent MD simulations of three peptides in water box have also been discussed for comparison. The results indicate that the unfolding process starts at the middle of the peptide. Pis-1 disrupts easily in the region of Val10-Lys14. Pis-1PG has a flexible N-terminal region, and the interaction between N-terminal and C-terminal is very weak. Pis-1AA has the most stable helical structure. In addition, percentage of native contacts and hydrogen bonds analysis are also performed. Lipid-peptide interaction analysis suggests that Pis-1 and Pis-1AA has a stronger interaction with the zwitterionic dioleoylphosphatidylcholine (DOPC) lipid bilayer than Pis-1PG. When compared with the results of peptide with membrane, peptides are unstable and unfolding quickly in water solution. Our results are applicable in examining diversities on hemolytic, antibacterial, and selectivity of antimicrobial peptides. PMID:22987590

The effect of dissolved ozone on heat exchanger structural materials (carbon steel, stainless steel, copper and 70:30 copper nickel) has been studied in laboratory experiments, within the concentration range of 0.1--1.0 ppm. The biocidal efficacy of ozone on planktonic and sessile growth of Pseudomonas fluorescens was studied in quiescent and flow conditions. Ozone was able to kill the total number of planktonic bacteria in synthetic cooling water. However, ozone is only capable of inducing a partial reduction of bacterial numbers in the case of sessile bacteria. The electrochemical behavior of copper and 70:30 copper nickel is studied through voltamperometric and corrosion potential vs. time measurements. Dissolved ozone would be able to modify the structure of the oxide layer. The electrochemical behavior of carbon steel and stainless steel in ozonated solutions of similar concentrations is also analyzed.

A study was conducted to determine the extent of galvanic corrosion that would be caused by copper-nickel sheathing of offshore steel platforms. The study investigated the effects of selected steel-to-CuNi area ratios on the magnitude and distribution of the galvanic current. One-year seawater exposure tests using segmented CuNi-steel pilings were conducted near Ocean City, NJ. The results of the study suggest that for piling configurations and lengths of copper-nickel sheathing similar to those included in the study, the maximum galvanic corrosion rate of the steel will be between 0.2 and 0.3 mm/y immediately next to the sheathing. The galvanic attack will be confined primarily to the first few meters of piling near to the sheathing. Beyond this, the intensity of galvanic attack will decline markedly.

The cooling-water discharge of a northeastern USA coastal power plant is an unnatural source of copper, nickel and zinc to the receiving waters. Passage of ambient Long Island Sound waters through the system of copper-nickel-zinc alloyed cooling-pipes doubles the dissolved concentrations of the metals, which otherwise occur at about 1 ..mu..gkg/sup -1/. Also, erosion of the pipes contributes like amounts of particulate metal forms to the effluent. In the effluent plume, total copper and zinc are conserved in the water column, although particulates quickly dissolve to augment soluble copper and zinc levels, as the plume is diluted. Dissolved nickel is apparently non-conservative; the excess disappears both by dilution and by reaction with the sediments.

Nanowires can be electrodeposited into partially etched porous alumina templates such that only a very small number of nanowires reach the top surface of the template. This allows transport measurements of small clusters or single nanowires in their alumina matrix by connecting leads to the hemispherical domes marking the protrusion of nanowires on the surface. Copper, nickel, and silver nanowires have been synthesized in this manner, and a more general synthesis method is proposed.

A physicochemical substantiation is performed for the organization of a combined flotation hydrometallurgical technology for the processing of the copper?nickel concentrates from the beneficiation of disseminated ores. This technology is used instead of the traditional pyrometallurgical technology providing the production of a sulfide concentrate with a total nickel, copper, and cobalt content of 14.64% for the through extraction of (wt %) 92.2 Ni, 74.0 Cu, 95.3 Co, 91.9 Pt, 95.9 Pd, and 96 Rh to the concentrate.

There is a need to expand the range of working electrodes which can be us in analytical voltametry. In this work, the synthesis of a thio containing (poly) N-Ethyl Tyramine electrode is described. Cyclic voltametry, SEM and EPMA were used to characterize the modified electrode. The ability of this electrode to uptake copper, nickel, mercury or cobalt ions from solution was investigated. Detection limits of the order of 0.1 ppm were estimated using differential pulse voltametry.

Ab initio electronic structure calculations of ferromagnetic copper-nickel alloys are carried out using the self-consistent-field Korringa-Kohn-Rostoker coherent potential approximation (SCF-KKR-CPA) method. The calculated lattice constants and magnetic moments of the alloy are in good agreement with the experimental results. It is also shown that the calculation is scalable with respect to the energy mesh and can be efficiently implemented on a massively parallel supercomputer.

Mesoporous carbons are used widely in adsorption, energy storage, super capacitors and catalyst supports on account of their high surface area and pore volume, inert nature and easy regeneration properties. An innovative approach was applied in the synthesis of mesoporous carbon using thermally modified pyrolysis fuel oil-based pitch and nano silica ball as carbon precursors and pore generators, respectively. The newly synthesized copper, nickel, potassium and manganese incorporated mesoporous carbon materials were characterized using physico-chemical characterization methods.

A physicochemical substantiation is performed for the organization of a combined flotation hydrometallurgical technology for the processing of the copper—nickel concentrates from the beneficiation of disseminated ores. This technology is used instead of the traditional pyrometallurgical technology providing the production of a sulfide concentrate with a total nickel, copper, and cobalt content of 14.64% for the through extraction of (wt %) 92.2 Ni, 74.0 Cu, 95.3 Co, 91.9 Pt, 95.9 Pd, and 96 Rh to the concentrate.

Copper is a problematic residual element in electric arc furnace steel production because it leads to "surface hot shortness," a cracking defect that occurs during hot rolling of steel. The cracking arises from a liquid, copper-rich phase that penetrates into and embrittles the austenite grain boundaries. The liquid forms because copper is nobler than iron and enriches at the oxide/metal interface during oxidation of iron after casting and reheating prior to hot rolling. This cracking can be reduced or eliminated by controlling the distribution of the copper-rich layer, i.e. preventing it from penetrating down the austenite grain boundaries. This study investigated the effect of alloy chemistry on the oxidation behavior and copper-rich liquid phase evolution. Alloy compositions were selected such that effects of copper, nickel, and reactive impurities (manganese, aluminum, and silicon) can be isolated. Industrially produced low carbon steels with varying copper, nickel and silicon contents were also studied. Alloys were oxidized in air or water vapor for times up to one hour at 1150°C. Oxidizing heat treatments were conducted in a thermogravimetric setup where the weight change could be measured during oxidation. Scanning electron microscopy was used to investigate in detail the oxide/metal interfaces. The modeling work focused on describing the enrichment and subsequent growth of the copper-rich layer. A fixed grid finite difference model was developed that predicts the evolution of the enriched region from given oxidation kinetics. The model predictions were validated under a variety of conditions using an iron - 0.3 wt% copper alloy. Deviations from the model predictions in these alloys suggest a critical amount of separated copper is necessary for substantial grain boundary penetration to occur and the required amount decreases when the gas contains water vapor. The parabolic oxidation rate for the iron-copper alloy did not differ from that of pure iron, but the parabolic rate for the nickel-containing alloys decreased by a factor of two. The microstructure of the iron-copper alloy consisted of a thin, copper-rich layer at the oxide/metal interface. Both nickel-containing alloys had perturbed oxide/metal interfaces consisting of alternating solid/liquid regions. The perturbed interfaces arise from unequal copper and nickel diffusivities in the ternary alloy. These diffusion effects are discussed in detail. The oxidation rate decrease is justified by the interface microstructure assuming that iron can only be rapidly supplied to the oxide through the liquid regions. Additions of manganese or aluminum to an iron-copper-nickel alloy did not lead to significant changes in behavior. Oxidation kinetics, amount of separated material, and interface roughness were unchanged. There was slightly more material occluded in the samples containing manganese and aluminum due to increased internal oxidation. These internal oxides do not affect the oxidation behavior because manganese can dissolve in wustite and the aluminum internal oxides are extremely small and heterogeneously dispersed near the oxide/metal interface. Additions of silicon, however, to an iron-copper-nickel alloy led to a significant decrease in oxidation rate, amount separated, and amount occluded. The differences in behavior are attributed to the formation of a fayalite layer at the oxide/metal interface. This layer blocks iron transport in the wustite layer, decreasing the oxidation rate and therefore the enrichment rate. Formation of the fayalite layer was found not to depend on the amount of nickel in the samples. The results above were then used to explain the oxidation behavior of low carbon steels containing copper, nickel, silicon, manganese, and aluminum. Steels containing high amounts of silicon had lower oxidation rates and higher amounts occluded. The amount of occluded material is much higher in the steels than in the iron-copper-nickel-silicon alloys. This is attributed to competition among the easily oxidizable impurities resulting in smal

Improved electrolytic cells for producing metals by the electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells, at least one electrode includes a protective layer comprising an oxide of the cell product metal formed upon an alloy of the cell product metal and a more noble metal. In the case of an aluminum reduction cell, the electrode can comprise an alloy of aluminum with copper, nickel, iron, or combinations thereof, upon which is formed an aluminum oxide protective layer.

This study was done to identify pollution prevention and waste minimization opportunities in the general plating department and the printed circuit board processing department. Recommendations for certain recycle and recovery technologies were mad in order to reduce usage of acids and the volume of heavy metal sludge that is formed at the industrial Wastewater Pretreatment Facility (IWPF). Some of these technologies discussed were acid purification, electrowinning, and ion exchange. Specific technologies are prescribed for specific processes. Those plating processes where the metals can be recovered are copper, nickel, gold, cadmium, tin, lead, and rhodium.

A brief description is given of the trap-ike complex of the Imangda region in the northwestern Siberian Platform. The part of dikes, forming a differentiated sequence of rocks, including those mineralized is shown to be of exploration importance. The paper discusses the problem of possible presence in this region of differentiated intrusions of the upper structural stage and the necessity to discover the signal dikes throughout the territory concerned with the aim of contouring the areas prospective for sulfide copper-nickel mineralization. 6 figures, 3 tables.

Hydrogen-induced cracking (HIC) resistance of gas-pipeline steels was assessed in laboratory tests on pipelines and fittings steels. The metallurgical parameters controlling HIC resistance were established. The effects of nonmetallic inclusions, sulfur content, alloy segregation, and microstructure are described. It is suggested that pipeline steels for sour gas/oil service should have a sulfur content 0.005% and effective inclusion shape control by calcium or REM treatment. Reduction of the manganese content to the minimum possible level and the use of quenched and tempered steels are also beneficial. Small additions of copper, nickel and/or chromium may offer protection under certain operating conditions.

The atmospheric corrosion of oxygen-free copper (CDA-102), 70/30 copper-nickel (CDA-715), and 7% aluminum bronze (CDA-613) in an irradiated moist air environment was investigated. Experiments were performed in both dry and 40% RH (@90{degree}C) air at temperatures of 90 and 150{degree}C. Initial corrosion rates were determined based on a combination of weight gain and weight loss measurements. Corrosion products observed were identified. These experiments support efforts by the Yucca Mountain Project (YMP) to evaluate possible metallic barrier materials for nuclear waste containers. 8 refs., 1 fig., 2 tabs.

Copper-nickel (CuNi) alloy nanoparticles with Curie temperatures (T{sub c}) from 40 to 60{sup o}C were synthesized by several techniques. Varying the synthesis parameters and post-treatment, as well as separations by size and T{sub c}, allow producing mediator nanoparticles for magnetic fluid hyperthermia with parametric feedback temperature control with desired parameters. In vitro and in vivo animal experiments have demonstrated the feasibility of the temperature-controlled heating of the tissue, laden with the particles, by an external alternating magnetic field.

More than 200 bronze objects found in Hanzhong, southwest Shaanxi Province, China, a frontier region of the Shang Kingdom during the Shang dynasty, have been analysed for their composition and microstructure. Forty-three typologically distinct, and probably culturally indigenous, items have been found to be compositionally distinctive as well. This paper presents analytical results of the two types of local Hanzhong bronzes, namely the sickle-shaped and sceptre-shaped objects. Three special alloys, arsenic bronze, antimonial bronze and copper-nickel-arsenic ternary alloy, are particularly emphasized and discussed. The archaeological context of Hanzhong bronzes and their significance for the archaeometallurgy research of the Shang period are discussed as well.

In the present work, metals (cadmium, lead, copper, nickel, tin, selenium, and mercury) have been estimated in the Ebro River (Spain) using the zebra mussel (Dreissena polymorpha) as an environmental bio-indicator. In two sequential studies, in 2006 and 2008, concentrations of metals were calculated in water as well as in the shells and fleshes of the zebra mussels. Samples were collected from assorted locations of the river. Metals were determined successfully at trace levels through voltamperometry, a sensitive technique. It has been noted that analysis of bioaccumulators like zebra mussels can be helpful in evaluating metal pollution in water.

The Dictyonema shale of the Toolseskoe deposit of the Estonian SSR has been separated by hydrocyclone and flotation methods into six fractions differing in their macro- and microcomponent compositions. Chemical analysis have been made of these fractions. On the basis of the results of the analyses the pair correlation coefficients between the macro- and microcomponents have been calculated. It has been found that molybdenum is connected primarily with the organic matter and vanadium with the components containing aluminum and calcium. Copper, nickel, and cobalt have significant values of the coefficient of correlation with pyrite sulfur.

The divalent copper, nickel, cobalt and trivalent chromium, molybdenium and iron chelate compounds derived from bis(acetylacetone) ethylenediimine were grafted on activated silica gel using a batch process in methanolic solution. The sequence of the maximum retention capacity was Cr(III)>Mo(III)>Fe(III)>Co(II)>Ni(II)>Cu(II). Calorimetric titration was employed to study the interaction of activated silica gel with these series of metal chelate compounds. Exothermic enthalpic results were obtained throughout all interactions process. The spontaneity of these systems was reflected in negative and positive free Gibbs energy from entropic values.

For the production of synthesis gas of high purity from a carbonaceous material by the oxidative gasification a metal oxide (oxidation agent) is used as the heat and oxygen transfer agent for the gasification reaction. The oxidation agent is reduced by the synthesis gas under the formation of carbon dioxide and carbon dioxide is utilized as the gasification agent for the carbonaceous material. The reduced oxidation agent is reoxidized by air. Naturally occuring iron containing minerals, manganese ore or synthetically prepared materials with contents of the oxides of iron, copper, nickel, manganese, cerum, uranium and/or cobalt can be used as metal oxides.

A ligand exchange liquid/liquid extraction method using dithiocarbamate complexes is elaborated for the graphite furnace atomic absorption spectrometry (GF-AAS) of seawater and marine interstitial water. Palladium is used for the exchange. This metal ensures a rapid and quantitative back-extraction. It simultaneously works as matrix modifier in the GF-AAS analysis. The proposed method is evaluated in the analysis of lead, copper, nickel, and cadmium in CASS-II marine reference seawater and samples from the North Sea. A microanalytical variant of the method is applied in marine interstitial water analysis down to sample volumes of 500 {mu}l. (orig.).

(+)-Totarol, a highly hydrophobic diterpenoid isolated from Podocarpus spp., is inhibitory towards the growth of diverse bacterial species. (+)-Totarol decreased the onset temperature of the gel to liquid-crystalline phase transition of DMPC and DMPG membranes and was immiscible with these lipids in the fluid phase at concentrations greater than 5 mol%. Different (+)-totarol/phospholipid mixtures having different stoichiometries appear to coexist with the pure phospholipid in the fluid phase. At concentrations greater than 15 mol% (+)-totarol completely suppressed the gel to liquid-crystalline phase transition in both DMPC and DMPG vesicles. Incorporation of increasing amounts of (+)-totarol into DEPE vesicles induced the appearance of the H(II) hexagonal phase at low temperatures in accordance with NMR data. At (+)-totarol concentrations between 5 and 35 mol% complex thermograms were observed, with new immiscible phases appearing at temperatures below the main transition of DEPE. Steady-state fluorescence anisotropy measurements showed that (+)-totarol decreased and increased the structural order of the phospholipid bilayer below and above the main gel to liquid-crystalline phase transition of DMPC respectively. The changes that (+)-totarol promotes in the physical properties of model membranes, compromising the functional integrity of the cell membrane, could explain its antibacterial effects. PMID:11286971

Proteins that translocate across cell membranes need to overcome a significant hydrophobic barrier. This is usually accomplished via specialized protein complexes, which provide a polar transmembrane pore. Exceptions to this include bacterial toxins, which insert into and cross the lipid bilayer itself. We are studying the mechanism by which large antibacterial proteins enter Escherichia coli via specific outer membrane proteins. Here we describe the use of neutron scattering to investigate the interaction of colicin N with its outer membrane receptor protein OmpF. The positions of lipids, colicin N, and OmpF were separately resolved within complex structures by the use of selective deuteration. Neutron reflectivity showed, in real time, that OmpF mediates the insertion of colicin N into lipid monolayers. This data were complemented by Brewster Angle Microscopy images, which showed a lateral association of OmpF in the presence of colicin N. Small angle neutron scattering experiments then defined the three-dimensional structure of the colicin N-OmpF complex. This revealed that colicin N unfolds and binds to the OmpF-lipid interface. The implications of this unfolding step for colicin translocation across membranes are discussed.

A new type of cochleate, able to microencapsulate water-soluble cationic drugs or peptides into its inter-lipid bi-layer space, was formed through interaction between negatively charged lipids and drugs or peptides acting as the inter-bi-layer bridges instead of multi-cationic metal ions. This new type of cochleate opened up to form large liposomes when treated with EDTA, suggesting that cationic organic molecules can be extracted from these cochleates in a way similar to multivalent metal ions from metal ion-bridged cochleates. Cochleates can be produced in sub-micron size using a method known as "hydrogel isolated cochleation" or simply by increasing the ratio of multivalent cationic peptides over negatively charged liposomes. When nanometer-sized cochleates and liposomes containing the same fluorescent labeled lipid component were incubated with human fibroblasts cells under identical conditions, cells exposed to cochleates showed bright fluorescent cell surfaces, whereas those incubated with liposomes did not. This result suggests that cochleates' edges made them fuse with the cell surfaces as compared to edge free liposomes. This mechanism of cochleates' fusion with cell membrane was supported by a bactericidal activity assay using tobramycin cochleates, which act by inhibiting intracellular ribosomes. Tobramycin bridged cochleates in nanometer size showed improved antibacterial activity than the drug's solution. PMID:18652885

In developing sediment quality criteria (SQC) for metals, it is essential that bioavailability be a prime consideration. Different studies have shown that while dry weight metal concentrations in sediments are not predictive of bioavailability, metal concentrations in interstitial (pore) water are correlated with observed biological effects. A key partitioning phase controlling cationic metal activity and toxicity in the sediment-interstitial water system is acid-volatile sulfide (AVS). Acid-volatile sulfide binds, on a mole-to-mole basis, a number of cationic metals of environmental concern (cadmium, copper, nickel, lead, zinc) forming insoluble sulfide complexes with minimal biological availability. Short-term (10-d) laboratory studies with a variety of marine and freshwater benthic organisms have demonstrated that when AVS concentrations in spiked or field-collected sediments exceed those of metals simultaneously extracted with the AVS, interstitial water metal concentrations remain below those predicted to cause effects, and toxicity does not occur. Similar observations have been made in life-cycle laboratory toxicity tests with amphipods and chironomids in marine and freshwater sediments spiked with cadmium and zinc, respectively. In addition, field colonization experiments, varying in length from several months to more than 1 year, with cadmium- or zinc-spiked freshwater and marine sediments, have demonstrated a lack of biological effects when there is sufficient AVS to limit interstitial water metal concentrations. These studies on metal bioavailability and toxicity in sediments serve as the basis for proposed SQC for the metals cadmium, copper, nickel, lead, and zinc.

The present study was conducted to consider practical 10,000 ampere conductor designs to meet the operating constraints for the ohmic heating coils of TNS and experimental Tokamak reactors. The conductor must simultaneously meet the requirements for mechanical support, cryostabilization, high overall winding current density, low mechanical and electrical losses, and mechanical and electrical integrity for cyclic pulsed operation for -7 T to +7 T in one second. A suggested winding is a set of nested tubes, each made up of a stack of pancake-wound bobbins. Each pancake is co-wound of a flat open superconductor braid, steel tape, and Kapton insulation. The strands of the braid consist of sectored copper regions separated by copper-nickel and surrounding a mixed-matrix copper, copper-nickel, and NbTi multifilament core. Strands 1.5 mm in diameter provide conservative cryostabilization at overall winding current densities adequate for the OH winding of an EPR-1 or TNS sized coil (approx.1500 amperes/cm/sup 2/). Eddy current and coupling losses are at acceptable levels, and hysteresis losses can be reduced within acceptable limits with 10 ..mu.. diameter filaments, providing the winding is graded, tube to tube. The basic conductor and winding concept can be extended to provide conductors of higher currents. A 2000 ampere model conductor has been fabricated from 0.94 mm diameter strands and tested in a reinforced pancake configuration. The measured maximum recovery current corresponds to a current density of 3500 amperes/cm/sup 2/ over the entire coil cross section.

The accommodation of chain-length mismatch in liquid crystal phase bilayers was examined by using deuterium nuclear magnetic resonance to obtain smoothed orientational order parameter profiles for acyl chains of both components in binary lipid mixture bilayers. Mixtures of dimyristoylphosphatidylcho...

Fifteen beta-lactam antibiotics were divided into four classes based on their antibacterial actions and beta-lactamase-inducing activities in Proteus vulgaris. One of these groups, which included cefmenoxime, ceftriaxone, cefuzonam, and cefotaxime, showed a clear paradoxical antibacterial activity a...

Maximum antibacterial activity was detected in Eucalyptus laevopinea, E. wilkinsoniana, and Myrtus communis. As a result of a study of different parts of the plant, the maximum antibacterial activity was found in leaves, and the minimum in the core. Pract...

The production of antibacterial compounds by yeasts and yeastlike fungi isolated from the phylloplane is reported. Aureobasidium pullulans, Citeromyces matritensis, Cryptococcus laurentii, Rhodotorula glutinis, and Sporobolomyces roseus produced antibacterial compounds inhibitory to both Pseudomonas...

We use electrospinning to prepare chitosan-PVA nanofibers containing graphene. The nanofibers can be directly used in wound healing: graphene, as an antibacterial material, can be beneficial for this. A possible antibacterial mechanism for graphene is presented.

A novel aqueous bilayer membrane that is formed from amphiphilic complexes of complementary hydrogen bond pairs provided a specific dye binding site similar to that of the conventional ammonium bilayer. Partial dissociation of the hydrogen bond pairs and the consequent component separation occurred by heating the aqueous bilayer to 80–100 °C.   

Membrane proteins are regulated by the lipid bilayer composition. Specific lipid-protein interactions rarely are involved, which suggests that the regulation is due to changes in some general bilayer property (or properties). The hydrophobic coupling between a membrane-spanning protein and the surrounding bilayer means that protein conformational changes may be associated with a reversible, local bilayer deformation. Lipid bilayers are elastic bodies, and the energetic cost of the bilayer deformation contributes to the total energetic cost of the protein conformational change. The energetics and kinetics of the protein conformational changes therefore will be regulated by the bilayer elasticity, which is determined by the lipid composition. This hydrophobic coupling mechanism has been studied extensively in gramicidin channels, where the channel-bilayer hydrophobic interactions link a "conformational" change (the monomerdimer transition) to an elastic bilayer deformation. Gramicidin channels thus are regulated by the lipid bilayer elastic properties (thickness, monolayer equilibrium curvature, and compression and bending moduli). To investigate whether this hydrophobic coupling mechanism could be a general mechanism regulating membrane protein function, we examined whether voltage-dependent skeletal-muscle sodium channels, expressed in HEK293 cells, are regulated by bilayer elasticity, as monitored using gramicidin A (gA) channels. Nonphysiological amphiphiles (beta-octyl-glucoside, Genapol X-100, Triton X-100, and reduced Triton X-100) that make lipid bilayers less "stiff", as measured using gA channels, shift the voltage dependence of sodium channel inactivation toward more hyperpolarized potentials. At low amphiphile concentration, the magnitude of the shift is linearly correlated to the change in gA channel lifetime. Cholesterol-depletion, which also reduces bilayer stiffness, causes a similar shift in sodium channel inactivation. These results provide strong support for the notion that bilayer-protein hydrophobic coupling allows the bilayer elastic properties to regulate membrane protein function.

The ceaseless opening and closing of the voltage-gated channels (VGCs) underlying cardiac rhythmicity is controlled, in each VGC, by four mobile voltage sensors embedded in bilayer. Every action potential necessitates extensive packing/repacking of voltage sensor domains with adjacent interacting lipid molecules. This renders VGC activity mechanosensitive (MS), i.e., energetically sensitive to the bilayer's mechanical state. Irreversible perturbations of sarcolemmal bilayer such as those associated with ischemia, reperfusion, inflammation, cortical-cytoskeleton abnormalities, bilayer-disrupting toxins, diet aberrations, etc, should therefore perturb VGC activity. Disordered/fluidized bilayer states that facilitate voltage sensor repacking, and thus make VGC opening too easy could, therefor...

The paper describes how element speciation is determined and how distribution patterns in biological matrices of vegetable, animal and human origin are established. It deals with sampling and the storage of samples, sample conditioning, separation operations, methods of detection and evaluation, and effect-related investigations of element speciation by coupled techniques. The analytics of aluminium, arsenic, lead, cadmium, chromium, iron, copper, nickel, mercury, selenium, zink and tin is described in exemplary manner. (orig.) [Deutsch] Der Aufsatz beschreibt den Nachweis von Elementspezies und die Erstellung von Verteilungsmustern in biologischen Matrices pflanzlicher, tierischer und menschlicher Herkunft. Er geht auf Probennahme und Probenlagerung, Probenvorbereitung, Trennoperationen, Detektionstechniken und Auswertungsmethoden sowie auf wirkungsbezogene Untersuchungen von Elementspezies in Verbundverfahren ein. Exemplarisch beschreibt er die Analytik von Aluminium, Arsen, Blei, Cadmium, Chrom, Eisen, Kupfer, Nickel, Quecksilber, Selen, Zink, und Zinn. (orig.)

Copper-??-alumina was prepared by ion exchange reactions starting with a sodium-??-alumina. Exchange from sodium ion to copper ion was done by immersing the sample in liquid cuprous chloride. Exchange of Na+ ion in ??-alumina to Cu+ ion was not complete as Na+ ion remained in the ??-alumina. Copper activity in solid copper–nickel alloys was measured by electromotive force (EMF) technique incorporating the partially exchanged (Cu+–Na+)-??-alumina as a solid electrolyte for temperatures between 870 and 1300?K. The activities of copper and nickel in the solid solution at these temperatures exhibited positive deviations from Raoult’s law. The activity data were compared with other investigators obtained using ZrO2+CaO or ThO2+Y2O3 solid electrolyte.   

Introduction - Plants can be used as bioindicators in the study of contamination processes by heavy metals. Most of the analytical methodologies used for determination of metals in plants are based on atomic techniques with previous wet digestion of the solid samples. Methodologies that allow direct metal measurements in solid samples are very attractive alternatives. Objective - To develop a new procedure for direct analysis of copper, nickel, cadmium and lead at very low concentration levels in leaves based on electrothermal atomic absorption spectroscopy (ET-AAS) with introduction of samples as a slurry. Methodology - In order to obtain accurate and precise results even at very low concentrations, the different parameters that influence the sample slurry preparation such as acid percent...

1.1 This guide presents a method for predicting reference transition temperature adjustments for irradiated light-water cooled power reactor pressure vessel materials based on Charpy V-notch 30-ftlbf (41-J) data. Radiation damage calculative procedures have been developed from a statistical analysis of an irradiated material database that was available as of May 2000. The embrittlement correlation used in this guide was developed using the following variables: copper and nickel contents, irradiation temperature, and neutron fluence. The form of the model was based on current understanding for two mechanisms of embrittlement: stable matrix damage (SMD) and copper-rich precipitation (CRP); saturation of copper effects (for different weld materials) was included. This guide is applicable for the following specific materials, copper, nickel, and phosphorus contents, range of irradiation temperature, and neutron fluence based on the overall database: 1.1.1 MaterialsA 533 Type B Class 1 and 2, A302 Grade B, A302 G...

The Shpack Landfill site is on the National Priorities List (NPL). The landfill received both domestic and industrial waste, including inorganic and organic chemicals as well as radioactive waste. Ground water contains vinyl chloride, trichloroethylene, trans-1,2-dichloroethylene, tetrachloroethylene, chromium, barium, copper, nickel, manganese, arsenic, cadmium, lead, polychlorinated biphenyl-1260 (Aroclor-1260), radium-226, alpha particles and beta particles. Surface and subsurface soil samples contained radium-226, uranium-238, uranium-235, uranium-234, and visual evidence of metal plating waste sludges. The site is considered to be of potential health concern because of the risk to human health caused by the potential for exposure to hazardous substances via ingestion of contaminated soils at the site and future ingestion of contaminated domestic well water.

In the present work, the influence of the competitive effect of inorganic ligands (carbonates, chlorides, fluorides, phosphates, nitrates and sulphates), which can be present in real multi-metal electroplating effluents, on the biosorption of chromium, copper, nickel and zinc ions by yeast cells of Saccharomyces cerevisiae was rationally examined. Additionally, chemical speciation studies allowed optimizing the amount of yeast biomass to be used in the treatment of effluents contaminated with nickel. The applicability of chemical simulation studies was tested using two simulated effluents and validated using one real electroplating effluent, all containing high concentrations of nickel (about 303mmoll^-^1). For nickel removal, heat-killed biomass of a brewing flocculent strain of S. cerevi...

An investigation has been undertaken into the performance of metal alloy anodes used to produce aluminum via an electrochemical method. Alumina was electrolyzed in NaF/AlF3 and KF/AlF3 electrolytes and mixtures thereof with copper-nickel-iron (Cu:Ni:Fe) alloy anodes and titanium diboride (TiB2) cathodes. The operating temperatures of the electrochemical cells ranged from 973?K to 1123?K (700??C to 850??C), with an anode current density of 5000?A/m2. Cells ranged in current capacity from 10 to 300?amperes, with oxygen gas formed at the anode and molten aluminum collected from the cathode. Posttest anodes were sectioned, and elemental maps were performed to characterize the distribution of the chemical phases, including the metal electrodes, bath phases, and aluminum metal production, which ...

In recent decades, mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals. Since 1990, the European moss survey has been repeated at five-yearly intervals. Although spatial patterns were metal-specific, in 2005 the lowest concentrations of metals in mosses were generally found in Scandinavia, the Baltic States and northern parts of the UK; the highest concentrations were generally found in Belgium and south-eastern Europe. The recent decline in emission and subsequent deposition of heavy metals across Europe has resulted in a decrease in the heavy metal concentration in mosses for the majority of metals. Since 1990, the concentration in mosses has declined the most for arsenic, cadmium, iron, lead and vanadium (52-72%), followed by copper, nickel and zi...

The Sipu region of North Guangxi is located in the southwest of the ?Jiangnan Ancient Land?, where there are developed the oldest stratum in southern China, the Proterozoic Sipu Group, and there are also largely exposed mafic intrusive rocks, mafic volcanic rocks and copper-nickel sulfide deposits. Both mafic intrusive rocks and volcanic rocks are rich in MgO (6.52%?26.39%), but poor in K2O (0.05%?1.00%) and TiO2 (0.33%?0.89%). They are also rich in trace elements such as Rb and Ba while poor in Ta, Nb and the like. Both of them have medium contents of rare-earth elements, 30.26×10?6?126.71×10?6, in which LREEs are slightly rich with ?LREE/?HREE of 1.35?2.46, ?Eu 0.79?1.33, displaying weak or no ?Eu anomaly, with the same geochemical features. The right-inclined distribution patterns and t...

Mechanical alloying of a mixture of copper and nickel powders has been applied for the preparation of copper-nickel alloy particles in the nanometer range. The particles were designed to be used for controlled magnetic hyperthermia applications. The milling conditions were optimized using the desired alloy composition. Utilizing a ball-to-powder mass ratio of 20, we could obtain a nanocrystalline Cu27.5Ni72.5 (at%) alloy with a crystallite size of around 10 nm and a Curie temperature of 45 °C.Thermal demagnetization in the vicinity of the Curie temperature of the nanoparticles was determined by thermomagnetic measurements using an adapted TGA-SDTA apparatus. The size and morphology of the particles were determined by XRD measurements and TEM analyses. The magnetic properties were also examined with a VSM. The magnetic heating effects were measured for the powdered material.

A new automated batch method for the determination of ultratrace metals (nanogram per liter level) was developed and validated. Instrumental and chemical parameters affecting the performance of the method were carefully assessed and optimized. A wide range of voltammetric methods under different chemical conditions were tested. Cadmium, lead and copper were determined by anodic stripping voltammetry (ASV), while nickel, cobalt, rhodium and uranium by adsorptive cathodic stripping voltammetry (AdCSV). The figures of merit of all of these methods were determined: very good precision and accuracy were achieved, e.g. relative percentage standard deviation in the 4-13% for ASV and 2-5% for AdCSV. The stripping methods were applied to the determination of cadmium, lead, copper, nickel, cobalt, rhodium and uranium in lake water samples and the results were found to be comparable with ICP-MS data. PMID:17586114

An experimental study was conducted on the chelation and electrolytic foam separation of trace amounts of copper, nickel, zinc, and cadmium from a synthetic chelated metal wastewater. Sodium ethylenediaminetetraacetate (EDTA), citrate, sodium diethyldithiocarbamate (NDDTC), and potassium ethyl xanthate (KEtX) were used with sodium dodecylsulfate (NaDS) as a foam-producing agent. Experimental results from an electrolytic foam separation process showed that chelating agents NDDTC and KEtX, due to their higher chelating strength and hydrophobic property, can efficiently separate Cu and Ni from chelated compounds (Cu, Ni/EDTA, and Cu, Ni/citrate). In a Cu-EDTA-NDDTC system with a chelating agent/metal ratio of 4, the residual Cu(II) concentration is 0.7 mg/L. The effects of chelating agent types and different chelating agents concentrations on the removal of metal ions were studied. The effect of NaDS dosage on flotation behavior and the efficiency of metal removal were also investigated.

The roles of the electrode material and geometry on the performance of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) optical emission spectroscopy source are described. The LS-APGD source has been interfaced to a high resolution JY RF-5000 polychromator allowing for simultaneous multiple element detection. This LS-APGD source operates at currents of 20-60mA and solution flow rates of 0.1-0.4mLmin^-^1. A glow discharge is generated between the surface of the electrolyte test solution exiting a glass capillary and the end of a metallic counterelectrode. Described here is an evaluation of how the counterelectrode material identity (copper, nickel, and stainless steel) and the electrode configuration (geometry) influence the analyte emission responses for a test solution co...

The company employs about forty people and operates for one or two eight hour shifts with an average of 315 racks of chrome plating per eight hour day. They plate a variety of metals including copper, nickel, gold, brass and chromium. Chromium is the major metal plated and is usually the last step in plating cycle. Most parts are copper plated and then nickel plated in preparation for chrome plating. The main difference between New Dimension Plating and other plating shops is the variety of parts plated. As New Dimension Plating is a job shop, a wide range of parts such as motorcycle accessories, stove parts, and custom items are metal finished. The plating lines are manual, meaning employees dip the racks into the tanks by hand. This fact along with the fact that parts vary greatly in size and shape accounts for the significant drag-out on the chromium plating line.

A number of spectrum lines of highly ionized copper, nickel, iron, chromium, and germanium have been observed and the corresponding transitions identified. The element under study is introduced into the discharge of the PLT Tokamak by means of rapid ablation by a laser pulse. The ionization state is generally distinguishable from the time behavior of the emitted light. New identifications of transitions are based on predicted wavelengths (from isoelectronic extrapolation and other data) and on approximate expected intensities. All the transitions pertain to the ground configurations of the respective ions, which are the only states strongly populated at tokamak plasma conditions. These lines are expected to be useful for spectroscopic plasma diagnostics in the 1-3 keV temperature range, and they provide direct measurement of intersystem energy separations from chromium through copper in the oxygen, nitrogen, and carbon isoelectronic sequences.

Copper precipitation in irradiated RPV steels is well known to have a deleterious effect on mechanical properties. In order to understand the contribution of thermal ageing to RPV embrittlement a high copper (0.44 at.%), high nickel (1.6 at.%) model RPV weld was thermally aged at 365 ^oC for times up to 90,000 h. Atom Probe Tomography (APT) was employed to study the precipitation of solutes, primarily copper, nickel, manganese and silicon within the matrix and at grain boundaries. As expected, a high number density of 1-4 nm radius copper rich precipitates was observed. Nickel, manganese and silicon were found at the precipitate matrix interface, and the evolution of the composition of this interface was investigated with ageing time. Segregation of solutes to grain boundaries particularly...

Five sorption materials were studied with focus on polishing pretreated stormwater: crushed limestone, shell-sand, zeolite and two granulates of olivine. These materials are commercially available at comparatively low cost and have been subjected to a minimum of modification from their natural states. The sorbents were tested towards phosphorus, arsenic, cadmium, chromium, copper, nickel, lead and zinc at concentration and conditions relevant for typical stormwater. The materials were tested for sorption capacity and kinetics. Desorption was tested under neutral and alkaline conditions and in the presence of chloride. For most sorbent/sorbate combinations, significant sorption occurred within the first minutes of contact between sorbent and sorbate. Treatment to the low microgram per liter range could be achieved by contact times of less than an hour. The study indicated that sorption filters can be designed for long life expectancy at comparatively low cost by applying the materials tested.

The leaching of copper, nickel and cobalt from polymetallic manganese nodules from the Indian Ocean was investigated using a fungus - Aspergillus niger. Parameters such as initial pH, pulp density, particle size and duration of leaching were optimized for the bio-recovery of metals. At an initial pH of 4.5, 35 C temperature and 5% (w/v) pulp density, about 97% Cu, 98% Ni, 86% Co, 91% Mn and 36% Fe were dissolved in 30days time using adapted fungus - as against only 4.9% Cu, 8.2% Ni, 27% Co, 6.3% Mn and 7.1% Fe solubilized in control experiment. The results indicate that A. niger released organic acids such as oxalic and citric acids which in turn reduced the host metal oxides/hydroxides to their lower valence states, and thus dissolving the base metals following the indirect mechanism. A c...

Column outflow experiments operated at steady state flow conditions do not allow the identification of rate limited release processes. This requires an alternative experimental methodology. In this study, the aim was to apply such a methodology in order to identify and quantify effective release rates of heavy metals from granular wastes. Column experiments were conducted with demolition waste and municipal waste incineration (MSWI) bottom ash using different flow velocities and multiple flow interruptions. The effluent was analyzed for heavy metals, DOC, electrical conductivity and pH. The breakthrough-curves were inversely modeled with a numerical code based on the advection?dispersion equation with first order mass-transfer and nonlinear interaction terms. Chromium, Copper, Nickel and A...

Samples of the welds from the Midland and Palisades reactors in the unirradiated condition and after neutron irradiation to a high fluence of up to 3.4 × 1023 m-2 (E > 1 MeV) have been characterized with the Oak Ridge National Laboratory’s local electrode atom probe. High number densities, ˜5 and ˜7 × 1023 m-3, respectively, of ˜2-nm-diameter copper-, nickel-, manganese- and silicon-enriched precipitates were observed after neutron irradiation. These copper-enriched precipitates were observed both in the matrix of the steel and also preferentially located along the dislocations. No appreciable differences were observed in the sizes or the compositions of the precipitates in the matrix and on the dislocations. The average interparticle distance along the dislocations was 11 ± 3 nm. Phosphorus segregation was also evident along the dislocations in both welds. No other nanoscale intragranular phases were observed in these neutron irradiated welds.

Environmental pollution due to heavy metals is having an increased impact on marine wildlife accentuated by anthropogenic changes in the planet including overfishing, agricultural runoff and marine emerging infectious diseases. Sea turtles are considered sentinels of ecological health in marine ecosystems. The objective of this study was to determine baseline concentrations of zinc, cadmium, copper, nickel, selenium, manganese, mercury and lead in blood of 22 clinically healthy, loggerhead turtles (Caretta caretta), captured for several reasons in Puerto Lopez Mateos, Baja California Sur, Mexico. Zinc was the most prevalent metal in blood (41.89mgg-1), followed by Selenium (10.92mgg-1). The mean concentration of toxic metal Cadmium was 6.12mgg-1 and 1.01mgg-1 respectively. Mean concentrati...

Fretting is a low amplitude oscillatory wear that occurs at component interfaces and can accelerate crack initiation as well as interfacial degradation. Prevalent in Ti-alloy contacts, fretting wear often occurs at the blade/disk interfaces of fan and compressor stages in turbine engines, causing premature component failure. In many cases, plasma sprayed CuNiIn (copper-nickel-indium) coatings and solid lubricants are applied to blade roots to mitigate the fretting problem. However, the CuNiIn coatings can cause severe damage to the uncoated Ti-alloy counter parts once the solid lubricants wear out. In this study, bench level gross slip fretting wear tests were conducted at room temperature on unlubricated Ti6Al4V (titanium, 6% aluminum, 4% vanadium) surfaces mated with CuNiIn and commercia...

Some persistent pesticides, as organochlorines, are not efficiently removed from usual wastewater treatment plants, unless a tertiary treatment, commonly activated carbon adsorption, is applied. The downside of this practice rests on its high regeneration costs. This fact motivated the research for alternative processes involving the use of natural materials. Pine bark was used in this work, to remove lindane from contaminated waters. The adsorptive capabilities of this material were studied (equilibrium time, adsorption model and saturation of the adsorbent) and the interference of some metals (iron, cadmium, copper, nickel and lead) was also investigated. Results showed an excellent efficiency of adsorption (average 80,65%) and that the presence of the studied metals did not affect both efficiency and the model of the adsorption, within the range of the concentration of the pesticide studied.

American Strategic Minerals brings together seven contributors in the fields of marine studies, mining engineering, earth sciences, and economics to discuss and analyze strategic minerals. The future demands of the United States upon limited sources of supply are examined and there is an analysis of alternative sources of strategic minerals from the seabed, including copper, nickel, manganese, and cobalt. The book contains an examination of the investments that the United States has made in developing countries that could affect both the national security and national economy of America in the years ahead. After a review of minerals policy in the United States, the conflicting interests that influence the President and Congress in making decisions about strategic minerals, and other dimensions of strategic minerals, are exposed to clarify both the facts and myths about supply and demand, security and danger, and high and low prices.

Our earlier studies indicate that the precursors that lead to thermal deposits can be formed/accelerated when the fuel is aged in the presence of copper. For convenience, the aging of jet fuels in the presence of copper has been studied using: (1) copper II ethyl acetoacetate (CuEA); and (2) accelerated aging in a Low Pressure Reactor. Long term studies are being conducted to establish that a reliable correlation exists between such lab tests and field conditions viz., storage at ambient conditions in the presence of copper-nickel alloy for an equivalent period. To date, the results for only one of the three fuels being examined are available. Thermal stabilities of the aged and non aged fuel were determined using the gravimetric JFTOT.

Abstract Flotation is a gravity separation process that originated from processing of minerals, and has nowadays found wide application, for instance, in industrial waste-water treatment. It is also useful in the concentration of a variety of dissolved chemical species often following a sorption process. The present review paper focuses on the removal of heavy metal ions from aqueous solution. The process mechanisms involved are either sorptive flotation where metal bonding agents, including biosorbents, are added and the subsequent complexes are separated downstream by flotation or other conventional flotation techniques, such as ion flotation are used. In the laboratory experiments described in this paper, zinc has been used as an example, but in addition copper, nickel, arsenic, etc. ar...

Atom probe tomography has played a key role in the understanding of the embrittlement of neutron irradiated reactor pressure vessel steels through the atomic level characterization of the microstructure. Atom probe tomography has been used to demonstrate the importance of the post weld stress relief treatment in reducing the matrix copper content in high copper alloys, the formation of 2-nm-diameter copper-, nickel-, manganese- and silicon-enriched precipitates during neutron irradiation in copper containing RPV steels, and the coarsening of these precipitates during post irradiation heat treatments. Atom probe tomography has been used to detect 2-nm-diameter nickel-, silicon- and manganese-enriched clusters in neutron irradiated low copper and copper free alloys. Atom probe tomography has...

This paper discusses the determination of minerals content (cadmium, cobalt, chromium, copper, nickel, lead, manganese, magnesium, iron, zinc, sodium, potassium and calcium) of six seagrass samples, Enhalus acoroides, Thalassia hemprichii, Halodule pinifolia, Syringodium isoetifolium, Cymodocea serrulata and Cymodocea rotundata using inductively coupled plasma optical emission spectrophotometry and flame photometer. Principal component analysis (PCA) and hierarchical cluster analysis revealed different mineral compositions of the seagrass samples. Among the 13 elements investigated, Ni 1.513, Na 690.167 and Ca 220.333; Cr 3.957; Mn 23.427, Zn 17.593 and Fe 156.567; Cd 0.357, Co 0.431, Pb 2.040, Mg 912.733 and K 300.9; Cu 7.8?mg/kg dry weight, respectively, were found at high concentrations...

IntroductionSeveral metals undergo redox cycling, producing free radicals and generating oxidative stress. The purpose of this study was to investigate in-vitro oxidative stress of orthodontic archwires made of various alloys. MethodsMouse fibroblast cells L929 were exposed to 6 types of archwires, and the concentration of the oxidative stress marker 8-hydroxy-2prime-deoxyguanosine in DNA was evaluated. Trypan blue dye was used in the determination of cell viability and numbers. ResultsStandard nickel-titanium archwires generated the highest oxidative stress, significantly higher than all other wires and the controls (P <0.05), and coated nickel-titanium, copper-nickel-titanium, and cobalt-chromium were lower than nickel-titanium (P <0.05), but higher than titanium-molybdenum and the negat...

Resistive transition of composite superconducting wires and cables that contain NbTi and Nb{sub 3}Sn is investigated. Several aspects, as the change of resistivity as a result of an increase of one or more of the variables such as current, magnetic field, temperature and strain are demonstrated. In its essence, the resistive transition of the super-conducting material refers to an electro-magnetic phenomenon: motion of flux lines. These investigations have been mainly performed by means of measurements of voltage-current characteristics. The shape of these characteristics of technical superconductors is determined by a large variety of factors, because these wires consist of filamentary super-conducting material embedded in a normal conducting matrix material as copper, copper-nickel or bronze. As a result, the resistive transition of the composite is determined by the basic flux-motion behaviour and large aspects of matrix resistivity, geometry e.t.c. (author). 105 refs.; 74 figs.; 12 tabs.

Using the radioactive isotopes the extraction of manganese (7) from solutions of caustic alkalis with TBP and TBA at 5-25 deg C in the presence of hypohalogenite-ions and catalytic amounts of copper, nickel or cobalt ions, is studied. The constants of alkali metal permanganate extraction with TBP decrease in the series of Li, Na, K, Rb, Cs: 0.12; 0.054; 0.032; 0.023; 0.017. MeMnOsub(4)xSsub(n) solvate transfer into organic phase, at that, for TBP n=4+-0.3, for TBA n=7-8. In the organic phase the salts are considerably dissociated. The thermodynamic functions for the extraction and dissociation of NaMnO/sub 4/ in TBP are determined.

Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time.

Lack of adequate quantities of clean surface water for use in wet (evaporative) cooling systems indicates the use of high-salinity waste waters, or cooled geothermal brines, for makeup purposes. High-chloride, aerated water represents an extremely corrosive environment. In order to determine metals suitable for use in such an environment, metal coupons were exposed to aerated, treated geothermal brine salted to a chloride concentration of 10,000 and 50,000 ppM (mg/L) for periods of up to 30 days. The exposed coupons were evaluated to determine the general, pitting, and crevice corrosion characteristics of the metals. The metals exhibiting corrosion resistance at 50,000 ppM chloride were then evaluated at 100,000 and 200,000 ppM chloride. Since these were screening tests to select materials for components to be used in a cooling system, with primary emphasis on condenser tubing, several materials were exposed for 4 to 10 months in pilot cooling tower test units with heat transfer for further corrosion evaluation. The results of the screening tests indicate that ferritic stainless steels (29-4-2 and SEA-CURE) exhibit excellent corrosion resistance at all levels of chloride concentration. Copper-nickel alloys (70/30 and Monel 400) exhibited excellent corrosion resistance in the high-saline water. The 70/30 copper-nickel alloy, which showed excellent resistance to general corrosion, exhibited mild pitting in the 30-day tests. This pitting was not apparent, however, after 6 months of exposure in the pilot cooling tower tests. The nickel-base alloys exhibited excellent corrosion resistance, but their high cost prevents their use unless no other material is found feasible. Other materials tested, although unsuitable for condenser tubing material, would be suitable as tube sheet material.

Amphiphilic aminoglycoside antimicrobials are an emerging class of new antibacterial agents with novel modes of action. Previous studies have shown that amphiphilic neomycin-B and kanamycin-A analogs restore potent antibacterial activity against Gram-positive neomycin-B- and kanamycin-A-resistant organisms. In this paper, we investigated the antibacterial properties of a series of amphiphilic tobramycin analogs. We prepared tobramycin–lipid conjugates, as well as tobramycin–peptide triazole conjugates, and studied their antibacterial activities against a panel of Gram-positive and Gram-negative bacterial strains, including isolates obtained from Canadian hospitals. Our results demonstrate that the antibacterial activity of amphiphilic tobramycin is greatly affected by the lengt...

We discuss about the antibacterial activities of Silver nanoparticles and compare them on both Gram negative and Gram positive bacteria in this investigation. The activities of Silver nanoparticles synthesized by electrolysis method are more in Gram (-) than Gram (+) bacteria. First time, we increase its antibacterial activities by using electrical power while on electrolysis synthesis and it is confirmed from its more antibacterial activities (For Escherichia coli bacteria). We investigate the changes of inner unit cell Lattice constant of Silver nanoparticles prepared in two different methods and its effects on antibacterial activities. We note that slight change of the lattice constant results in the enhancement of its antibacterial activities.

The relation between functions of the antibacterial resin designed by kneading and dispersion conditions of antibacterial particles was clarified, and the addition rate of antibacterial agents and kneading conditions for designing the antibacterial resin superior in functions were studied. Calculation of the effective range of a single antibacterial particle was also attempted. The effectiveness of the antibacterial resin correlated with the dispersion effectiveness number defined as the product of the dispersion and area ratio of antibacterial agent particles. Antibacterial materials could be thus designed under the condition with the large dispersion effectiveness number. The optimum kneading conditions were established to design the antibacterial resin with more excellent properties. It was suggested that the plane contour line graph should be used to represent the kneading conditions and antibacterial resin effectiveness to easily design the superior resin in less experiments. The effective range of a single antibacterial agent particle was estimated to be nearly 5.5 times as large as the particle diameter. 5 refs., 8 figs.

Restorative materials in the new era should be “bio-active” and antibacterial effects are highlighted as one of the important properties. In order to achieve resin-based restoratives with antibacterial effects, an antibacterial monomer MDPB has been developed. The primer incorporating MDPB demonstrated cavity-disinfecting effects, and the world's first antibacterial adhesive system employing the MDPB-containing primer was successfully commercialized. MDPB is potentially applicable to various restoratives since immobilization of the antibacterial component by polymerization of MDPB enables no deterioration in mechanical properties of cured resins and exhibition of inhibitory effects against bacterial growth on their surfaces. For glass-ionomer cements used for atraumatic restorative treatment, the approach to provide antibacterial activity has been attempted by addition of chlorhexidine. Incorporation of 1% chlorhexidine diacetate was found to be optimal to give appropriate antibacterial and physical properties, being effective to reduce the bacteria in affected and infected dentin in vivo.   

Membrane protein function is regulated by the host lipid bilayer composition. This regulation may depend on specific chemical interactions between proteins and individual molecules in the bilayer, as well as on non-specific interactions between proteins and the bilayer behaving as a physical entity with collective physical properties (e.g. thickness, intrinsic monolayer curvature or elastic moduli). Studies in physico-chemical model systems have demonstrated that changes in bilayer physical properties can regulate membrane protein function by altering the energetic cost of the bilayer deformation associated with a protein conformational change. This type of regulation is well characterized, and its mechanistic elucidation is an interdisciplinary field bordering on physics, chemistry and biology. Changes in lipid composition that alter bilayer physical properties (including cholesterol, polyunsaturated fatty acids, other lipid metabolites and amphiphiles) regulate a wide range of membrane proteins in a seemingly non-specific manner. The commonality of the changes in protein function suggests an underlying physical mechanism, and recent studies show that at least some of the changes are caused by altered bilayer physical properties. This advance is because of the introduction of new tools for studying lipid bilayer regulation of protein function. The present review provides an introduction to the regulation of membrane protein function by the bilayer physical properties. We further describe the use of gramicidin channels as molecular force probes for studying this mechanism, with a unique ability to discriminate between consequences of changes in monolayer curvature and bilayer elastic moduli.

Several studies have been performed to assess the effectivesness of the antibacterial coating of a biomaterial to reduce surgical site infection. However, evaluations of these materials are inconsistent, and therefore it is difficult to compare their antibacterial performance. In this study, we evaluated the influence of different media such as nutrient broth (NB), Mueller-Hinton broth (MHB) and fetal bovine serum (FBS) on the antibacterial activity of AgNO3- or gentamicin-added bone cement using a modified ISO 22196 standard to devise a method to evaluate the antibacterial activity of biomaterials in vitro. The antibacterial activity results against Staphylococcus aureus and Escherichia coil were different in each medium. The antibacterial activity of AgNO3 in FBS was lower than the other media, whereas the antibacterial activity of gentamicin in FBS was higher than in the other media. It was assumed that the fluctuating antibacterial activity was influenced by serum components. The results showed that the ISO 22196 antibacterial evaluation method is suitable to evaluate antibacterial biomaterials after modifying the medium to FBS. PMID:20361518

Pore formation of lipid bilayers under mechanical stress is critical to biological processes. A series of coarse grained molecular dynamics simulations of lipid bilayers with carbon nanoparticles different in size have been performed. Surface tension was applied to study the disruption of lipid bilayers by nanoparticles and the formation of pores inside the bilayers. The presence of small nanoparticles enhances the probability of water penetration thus decreasing the membrane rupture tension, while big nanoparticles have the opposite effect. Nanoparticle volume affects bilayer strength indirectly, and particle surface density can complicate the interaction. The structural, dynamic, elastic properties and lateral densities of lipid bilayers with nanoparticles under mechanical stress were analyzed. The results demonstrate the ability of nanoparticles to adjust the structural and dynamic properties of a lipid membrane, and to efficiently regulate the pore formation behavior and hydrophobicity of membranes. PMID:23165312

Photochromic behaviors of hemithioindigo (HT) derivatives in bilayer membrane matrices and related aqueous system are investigated. HT derivatives were incorporated into bilayer membrane matrices at a molar ratio to bilayer amphiphiles of 0.01. Under these conditions, HT amphiphiles having an ammonio group disperse molecularly in the array bilayer membranes, and show the simple photochromism as in the organic solutions. For a HT derivative having no hydrophilic group, on the other hand, irreversible photobleaching proceeds in addition to the photochromic reaction possibly as a result of cluster formation in the bilayer membranes. E-Form conversion at the photostationary state and the E to Z thermal isomerization rate is largely influenced by the crystal to liquid crystal phase transition of the bilayer matrices.   

Bilayer graphene exhibit many unusual physical properties, including a gate tunable electronic bandgap, and there is great interest in using it for novel electronic and optical devices. Understanding ultrafast dynamics in bilayer graphene is a prerequisite for many of its potential applications. We use ultrafsat pump-probe spectroscopy to investigate such ultrafast electron relaxation behavior in bilayer graphene. In this talk, I will discuss the observed dynamic relaxations taking place in femto- and pico-second time scales..

This article describes the fluorescence microscopy and imaging ellipsometry-based characterization of supported phospholipid bilayer formation on elastomeric substrates and its application in microcontact printing of spatially patterned phospholipid bilayers. Elastomeric stamps, displaying a uniformly spaced array of square wells (20, 50, and 100 mum linear dimensions), are prepared using poly(dimethyl)siloxane from photolithographically derived silicon masters. Exposing elastomeric stamps, following UV/ozone-induced oxidation, to a solution of small unilamellar phospholipid vesicles results in the formation of a 2D contiguous, fluid phospholipid bilayers. The bilayer covers both the elevated and depressed regions of the stamp and exhibits a lateral connectivity allowing molecular transport across the topographic boundaries. Applications of these bilayer-coated elastomeric stamps in microcontact printing of lipid bilayers reveal a fluid-tearing process wherein the bilayer in contact regions selectively transfers with 75-90% efficiency, leaving behind unperturbed patches in the depressed regions of the stamp. Next, using cholera-toxin binding fluid POPC bilayers that have been asymmetrically doped with ganglioside Gm1 ligand in the outer leaflets, we examine whether the microcontact transfer of bilayers results in the inversion of the lipid leaflets. Our results suggest a complex transfer process involving at least partial bilayer reorganization and molecular re-equilibration during (or upon) substrate transfer. Taken together, the study sheds light on the structuring of lipid inks on PDMS elastomers and provides clues regarding the mechanism of bilayer transfer. It further highlights some important differences in stamping fluid bilayers from the more routine applications of stamping in the creation of patterned self-assembled monolayers. PMID:17979304

Study of in vitro antibacterial activity of extracts from the plants T. chebula, E. alba and O. sanctum was carried out by the disk diffusion technique. All showed such activity against human pathogenic Gram positive and Gram negative bacteria. The activity against Salmonella organisms was shown only by T. chebula; against Shigella organisms by T. chebula and E. alha; but not by O. sanctum. The widest spectrum of antibacterial activity was shown by T. chebula. It was also most potent. The antibacterial spectrum of E. alba was in between that of T. chebula and O. sanctum. The narrowest spectrum of antibacterial activity was also most potent. The antibacterial spectrum of E. alba was in between that of T. chebula and O. sanctum. The narrowest spectrum of antibacterial activity was observed in O. sanctum. PMID:2793213

The goal of this paper was to establish the durability profile of antibacterial multilayer thin films under storage and usage conditions. Thin films were built on stainless steel (SS) by means of a layer-by-layer process alternating a negatively charged polyelectrolyte, polyacrylic acid, with a cationic antibacterial peptide, nisin. SS coupons coated with the antibacterial film were challenged under environmental and usage conditions likely to be encountered in real-world applications. The change in antibacterial activity elicited by the challenge was used as an indicator of multilayer film resistance. Antibacterial SS samples could be stored for several weeks at 4°C in ambient air and antibacterial films were resistant to dipping and mild wiping in water and neutral detergent. The multilayer coating showed some weaknesses, however, that need to be addressed. PMID:22530698

Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned with these two antibacterial agents for preparation of antibacterial stainless steel (SS). The antibacterial properties and corrosion resistance of AISI 420 stainless steel implanted by silver and copper ions were investigated. Due to the cooperative antibacterial effect of silver and copper ions, the Ag/Cu implanted SS showed excellent antibacterial activities against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) at a total implantation dose of 2?1017 ions/cm2. Electrochemical polarization curves revealed that the corrosion resistance of Ag/Cu implanted SS was slightly enhanced as compared with that of un-implanted SS. The implanted layer was ...

Membranes play key regulatory roles in biological processes, with bilayer composition exerting marked effects on binding affinities and catalytic activities of a number of membrane-associated proteins. In particular, proteins involved in diverse processes such as vesicle fusion, intracellular signaling cascades, and blood coagulation interact specifically with anionic lipids such as phosphatidylserine (PS) in the presence of Ca2+ ions. While Ca2+ is suspected to induce PS clustering in mixed phospholipid bilayers, the detailed structural effects of this ion on anionic lipids are not established. In this study, combining magic angle spinning (MAS) solid-state NMR (SSNMR) measurements of isotopically labeled serine headgroups in mixed lipid bilayers with molecular dynamics (MD) simulations of PS lipid bilayers in the presence of different counterions, we provide site-resolved insights into the effects of Ca2+ on the structure and dynamics of lipid bilayers. Ca2+-induced conformational changes of PS in mixed bilayers are observed in both liposomes and Nanodiscs, a nanoscale membrane-mimetic of bilayer patches. Site-resolved multidimensional correlation SSNMR spectra of bilayers containing 13C, 15N-labeled PS demonstrate that Ca2+ ions promote two major PS headgroup conformations, which are well resolved in two-dimensional 13C-13C, 15N-13C and 31P-13C spectra. The results of MD simulations performed on PS lipid bilayers in the presence or absence of Ca2+ provide an atomic view of the conformational effects underlying the observed spectra.

The interpretation of experimental observations of the dependence of membrane protein function on the properties of the lipid membrane environment calls for a consideration of the energy cost of protein-bilayer interactions, including the protein-bilayer hydrophobic mismatch. We present a novel (to our knowledge) multiscale computational approach for quantifying the hydrophobic mismatch-driven remodeling of membrane bilayers by multihelical membrane proteins. The method accounts for both the membrane remodeling energy and the energy contribution from any partial (incomplete) alleviation of the hydrophobic mismatch by membrane remodeling. Overcoming previous limitations, it allows for radially asymmetric bilayer deformations produced by multihelical proteins, and takes into account the irre...

The stacking-dependent electronic structure and transport properties of bilayer graphene nanoribbons suspended between gold electrodes are investigated using density functional theory coupled with non-equilibrium Green's functional method. We find substantially enhanced electron transmission as well as tunneling currents in the AA stacking of bilayer nanoribbons compared to either single-layer or AB stacked bilayer nanoribbons. Interlayer separation between the nanoribbons appears to have a profound impact on the conducting features of the bilayer nanoribbons, which is found to be closely related to the topology and overlap between the edge-localized p orbitals.

A fluorescently labeled resorcinarene cavitand has been successfully embedded in DLPC lipid vesicles and imaged using confocal microscopy. The cavitand resides exclusively in the bilayer. PMID:23144560

We have carried out extensive Monte Carlo simulations of the fusion of tense apposed bilayers formed by amphiphilic molecules within the framework of a coarse grained lattice model. The fusion pathway differs from the usual stalk mechanism. Stalks do form between the apposed bilayers, but rather than expand radially to form an axial-symmetric hemifusion diaphragm of the cis leaves of both bilayers, they promote in their vicinity the nucleation of small holes in the bilayers. Two subsequent paths are observed: (i) The stalk encircles a hole in one bilayer creating a diaphragm comprised of both leaves of the other intact bilayer, and which ruptures to complete the fusion pore. (ii) Before the stalk can encircle a hole in one bilayer, a second hole forms in the other bilayer, and the stalk aligns and encircles them both to complete the fusion pore. Both pathways give rise to an increase in mixing between the cis and trans leaves of the bilayer and allow for leakage.

The influence of some amphiphilic (diethyl, dipropyl, and dibutyl) esters of (1,1-dimethyl-3-oxobutyl) phosphonic acid with the regularly changing number of CH2 groups in the hydrocarbon (hydrophobic) moiety on the lateral diffusion of dioleoyl phosphatidylcholine lipid and transmembrane diffusion of water in the oriented multibilayer system was studied by 1H pulsed field gradient NMR at phosphonate concentrations up to 30 mol %. The shape of the 31P NMR spectra and the dependence of the shape of the 1H NMR spectra on the bilayer orientation suggest that the presence of phosphonates does not affect the phase state of the system. The lamellar liquid crystalline phase remains unchanged, and phosphonate molecules become incorporated into the bilayer and have the same orientation as phospholipid molecules. The presence of phosphonates in the lipid bilayer increases the coefficients of lipid lateral diffusion and water diffusion through bilayers. This effect depends monotonically on the number of CH2 groups in the phosphonate molecule. The most probable place for the incorporation of amphiphilic phosphonate molecules is the hydrophilic/hydrophobic interphase region of the bilayer. The molecules incorporated into the interphase disorder the bilayer and increase lateral diffusion of lipids and bilayer permeability compared with the ester-free bilayer. When the number of CH2 groups in the ester molecule increases from diethyl to dibutyl phosphonate, the arrangement of lipid hydrocarbon tails becomes more ordered. This decreases the lipid lateral diffusion coefficient and bilayer permeability to water molecules.

We have studied antibacterial activities of model peptides based on Pleurocidin (Ple). In this study, to investigate the effect of the C-terminal portion of these model peptides on antibacterial activity, we synthesized several short peptides which are devoid of the C-terminal four and more amino acid residues from the corresponding model peptides and examined their biological activities and behaviors against lipid and cell membranes. Removal of the C-terminal four residues resulted in maintained antibacterial activity and reduction of hemolytic activity.   

A percutaneous device with antibacterial activity and good biocompatibility is desired for clinical applications. Three types of antibacterial agent: lactoferrin (LF), tetracycline (TC), and gatifloxacin (GFLX) were immobilized on the surface of an ethylene-vinyl alcohol copolymer (EVOH) using a liquid phase coating process. In this process, an EVOH plate was alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable calcium phosphate solution supplemented with 4, 40, or 400 microg/mL of the antibacterial agent. As a result, the antibacterial agent was immobilized on the EVOH surface in the form of an antibacterial agent-apatite composite layer. The amount of immobilized antibacterial agent increased with increasing absorption affinity for apatite in the order: GFLXantibacterial agent from the composite was ordered in the opposite sense; i.e., LFantibacterial activity against Escherichia coli and Staphylococcus aureus, and would be useful as materials in percutaneous devices having antibacterial activity and good biocompatibility. PMID:16487584

The antibacterial activity of xanthorrhizol, isolated from the methanol extract of Curcuma xanthorrhiza roots, was evaluated against oral microorganisms in comparison with chlorhexidine. PMID:10844172

Antibacterial surface modification of biomedical materials has evolved as a potentially effective method for preventing bacterial proliferation on the surfaces of devices. However, thin antibacterial coatings or modified layers can be easily worn down when interacting with other surfaces in relative motion, thus leading to a low durability of the antibacterial surface. To this end, novel biomaterial surfaces with antibacterial Ag agents and a wear-resistant S-phase have been generated on stainless steel by duplex plasma silvering-nitriding techniques for application to load-bearing medical devices. The chemical composition, microstructure, surface topography, roughness and wettability of SS surfaces were characterised using glow discharge optical emission spectroscopy, energy-dispersive sp...

Objectives Plaque is never fully removed by brushing and may act as a reservoir for antibacterial ingredients, contributing to their substantive action. This study investigates the contribution of plaque-left-behind and saliva towards substantivity of three antibacterial toothpastes versus a control paste without antibacterial claims. Materials and methods First, volunteers brushed 2 weeks with a control or antibacterial toothpaste. Next, plaque and saliva samples were collected 6 and 12 h after brushing and bacterial concentrations and viabilities were measured. The contributions of plaque and saliva towards substantivity were determined by combining control plaques with experimental plaque or saliva samples and subsequently assessing their viabilities. Bacterial compositions in the vario...

The present study was carried out to evaluate the possible in vitro antibacterial potential of extracts of Eugenia jambolana seeds against multidrug-resistant human bacterial pathogens. Agar well diffusion and microbroth dilution assay methods were used for antibacterial susceptibility testing. Kill-kinetics study was done to know the rate and extent of bacterial killing. Phytochemical analysis and TLC-bioautography were performed by colour tests to characterize the putative compounds responsible for this antibacterial activity. Cytotoxic potential was evaluated on human erythrocytes by haemolytic assay method and acute oral toxicity study was done in mice. The plant extracts demonstrated varying degrees of strain specific antibacterial activity against all the test isolates. Further, ethy...

Effects of nucleopolyhedrovirus (NPV) on antibacterial peptide gene expression and peptide production in Bombyx mori larvae remain unclear. Antibacterial activity was first examined with the hemolymph from B. mori larvae infected with B. mori NPV (BmNPV) and injected with bacterial lipopolysaccharide (LPS) 72 h postinfection (p.i.). No antibacterial activity was detected. Expression of four antibacterial peptide genes were next analyzed in B. mori larvae infected with BmNPV. Although antibacterial peptide genes were activated upon injection of LPS in the larvae infected with BmNPV, none were triggered by BmNPV alone. Production of the antibacterial peptide cecropin B was next examined by Western blotting. Cecropin B was not detected from 72 to 96 h p.i. The absence of cecropin B was coincident with an increase in BmNPV cysteine proteinase (CP) activity. Cecropin B production was confirmed at 96 h p.i. in the larvae infected with CP-deficient BmNPV, indicating that the antibacterial peptides are degraded by BmNPV-CP at a very late stage of viral infection. These results suggest that BmNPV neither activates nor suppresses gene expression of antibacterial peptides and that absence of antibacterial activity is due to BmNPV-CP in B. mori larvae.   

Natural dyes have attracted increasing worldwide attention because of the carcinogenicity and environmental effects of synthetic dyes. In this study, wool fabric was treated with tannin-rich extracts of Punica granatum peel and walnut shell in combination with some mordants. The effect of various mordants on the colorimetric and antibacterial properties of wool fabrics was investigated. The results showed that pretreatment with metallic mordants substantially improved the dyeing and fastness properties of wool fabrics. The extracts of Punica granatum peel and walnut shell showed a significant antibacterial activity at 5% concentration. In addition, antibacterial activity was dramatically enhanced using metallic salts. The antibacterial activity of samples dyed with natural dyes and without...

Bilayer tableting technology has gained popularity in recent times, as bilayer tablets offer several advantages over conventional tablets. There is a dearth of knowledge on the impact of material properties and process conditions on the performance of bilayer tablets. This paper takes a statistical approach to develop a model that will determine the effect of the material properties and bilayer compression process parameters on the bonding strength and mode of breakage of bilayer tablets. Experiments were carried out at pilot scale to simulate the commercial manufacturing conditions. As part of this endeavor, a seven-factor half-fraction factorial (2(7-1)) design was executed to study the effect of bilayer tablet compression process factors on the bonding strength of bilayer tablets. Factors studied in this work include: material properties (plastic and brittle), layer ratio, dwell time, layer sequence, first- and second-layer forces, and lubricant concentration. Bilayer tablets manufactured in this study were tested using the axial tester, as it considers both the interfacial and individual layer bonding strengths. Responses of the experiments were analyzed using PROC GLM of SAS (SAS Institute Inc, Cary, North Carolina). A model was fit using all the responses to determine the significant interactions (p?bilayer compacts and also on mode of fracture. Bilayer tablets made with brittle materials in both the layers are strongest, and fracture occurred in the first layer indicating that interface is stronger than layers. Significant interactions were observed between the selected factors and these results will provide an insight into the interplay of material properties, process parameters, and lubricant concentration on the bonding strength and mode of breakage of bilayer tablets. PMID:22976242

A compound containing at least two aromatic rings covalently bonded together, with each aromatic ring containing at least one oxyacetamide-based side chain, the compound being capable of forming a chloride ion channel across a lipid bilayer, and transporting chloride ion across the lipid bilayer.

Small-angle neutron scattering is used to determine the temperature dependence of the lamellar repeat distance in an aqueous multilamellar solution of phospholipid bilayers. A thermal anomaly in the swelling behavior is observed at the bilayer phase transition. The anomalous behavior can be suppress...

Knowledge of the molecular packing of lipids and water in lipid bilayers is important for understanding bilayer mechanics and thermodynamics. Information on packing is most often obtained from x-ray or neutron diffraction measurements. Given the d spacing, composition, and partial specific volumes o...

A simple method is described for promoting and detecting fusion of liposomes with planar bilayer membranes. Liposomes containing ergosterol are doped with the pore-forming antibiotic nystatin, and the planar bilayer is kept ergosterol-free. Under these conditions, when a transbilayer salt gradient i...

The high-k dielectric TiO2/ZrO2 bilayer composite film was prepared on a Si substrate by radio frequency magnetron sputtering and post annealing in N2 at various temperatures in the range of 573 K to 973 K. Transmission electron microscopy observation revealed that the bilayer film fully mixed toget...

The dipole potential of lipid bilayer membrane controls the difference in permeability of the membrane to oppositely charged ions. We have combined molecular dynamics (MD) simulations and experimental studies to determine changes in electric field and electrostatic potential of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid bilayer in response to applied membrane tension. MD simulations based on CHARMM36 force field showed that electrostatic potential of DOPC bilayer decreases by ~45mV in the physiologically relevant range of membrane tension values (0 to 15dyn/cm). The electrostatic field exhibits a peak (~0.8×10(9)V/m) near the water/lipid interface which shifts by 0.9Å towards the bilayer center at 15dyn/cm. Maximum membrane tension of 15dyn/cm caused 6.4% increase in area per lipid, 4.7% decrease in bilayer thickness and 1.4% increase in the volume of the bilayer. Dipole-potential sensitive fluorescent probes were used to detect membrane tension induced changes in DOPC vesicles exposed to osmotic stress. Experiments confirmed that dipole potential of DOPC bilayer decreases at higher membrane tensions. These results are suggestive of a potentially new mechanosensing mechanism by which mechanically induced structural changes in the lipid bilayer membrane could modulate the function of membrane proteins by altering electrostatic interactions and energetics of protein conformational states. PMID:21722624

This experiment presents a new approach to measure elasticity parameters of lipid bilayers. We have deposited a stack of phospholipid bilayers on a silicon surface grating defined by e-beam lithography. The periodic surface profile acts as a boundary condition which imposes a controlled strain in th...

The lamellar D spacing has been measured for oriented stacks of lecithin bilayers prepared on a variety of solid substrates and hydrated from the vapor. We find that, when the bilayers are in the L(alpha) phase near 100% relative humidity, the D spacing is consistently larger when the substrate is r...

The in-plane ionic conductivity of the approximately 1-nm-thick aqueous layer separating a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer membrane and a glass support was investigated. The aqueous layer conductivity was measured by tip-dip deposition of a POPC bilayer onto the surface of a 20- to 75-microm-thick glass membrane containing a single conical-shaped nanopore and recording the current-voltage (i-V) behavior of the glass membrane nanopore/POPC bilayer structure. The steady-state current across the glass membrane passes through the nanopore (45-480 nm radius) and spreads radially outward within the aqueous layer between the glass support and bilayer. This aqueous layer corresponds to the dominant resistance of the glass membrane nanopore/POPC bilayer structure. Fluorescence recovery after photobleaching measurements using dye-labeled lipids verified that the POPC bilayer maintains a significant degree of fluidity on the glass membrane. The slopes of ohmic i-V curves yield an aqueous layer conductivity of (3 +/- 1) x 10(-3) Omega(-1) cm(-1) assuming a layer thickness of 1.0 nm. This conductivity is essentially independent of the concentration of KCl in the bulk solution (10-4 to 1 M) in contact with the membrane. The results indicate that the concentration and mobility of charge carriers in the aqueous layer between the glass support and bilayer are largely determined by the local structure of the glass/water/bilayer interface. PMID:17129059

A protoporphyrin IX derivative having three long alkyl chains and an axial imidazole (lipidprotoporphyrin) was homogeneously embedded into the bilayer membrane of the phospholipid vesicle. The O2-binding affinity of the lipidprotoheme was affected by the phase transition of the bilayer membrane, reflecting the change in the O2-association rate constant.   

Charged surfactant bilayers deposited in thick multilayer films and swollen in vapor or in solution have been studied by coherent X-ray scattering. We report a pronounced static speckle pattern which persists under conditions of full hydration, despite the fact that the bilayers are fluid, relativel...

Abstract The protein surface usually exhibits one or a few charged spots. If a lipid bilayer contains a significant amount of lipids with oppositely charged head groups, protein adsorption on a bilayer may be energetically favourable due to the protein-lipid electrostatic interaction. The sp...

New protoporphyrin IX derivatives having four amphiphilic and/or lipophilic alkyl chains (lipidporphyrins) were synthesized. The lipidporphyrins were efficiently incorporated into the bilayer membrane of phospholipid vesicle without a stacked arrangement. Homogeneous dispersing property of the lipidporphyrins in the bilayer membrane was maintained after polymerization of the phospholipid molecules.   

We have adsorbed plasmid PuC19 DNA on a supported bilayer. The mobility of the lipids within the bilayer ensured a 2D equilibrium of the DNA molecule. By varying the fraction of cationic lipids in the membrane, we have tuned the surface charge. Plasmids conformations were imaged by Atomic Force Microscopy (AFM).We performed two sets of experiments: deposition from salt free solution on charged bilayers and deposition from salty solutions on neutral bilayers. Plasmids can be seen as rings, completely opened structures, or tightly supercoiled plectonemes, depending on the experimental conditions. The plectonemic conformation is observed either on charged surfaces (in the absence of salt) or at 30 mM salt concentration on a neutral bilayer. We demonstrate the equivalence of surface screening by mobile interfacial charges and bulk screening from salt ions.

Supported lipid bilayers (SLBs) were prepared on glass and silicon slides grafted with polyethylene glycol (PEG) and covalently bound cholesteryl anchors to fix the lipid bilayer on the surface. Phospholipid bilayers and bilayers modified by addition of covalently bound PEG were investigated. Using contact angle measurements, the surface energy components of bilayer surfaces were analyzed using van Oss' and Owens-Wendt's methods. A quantitative correlation between the polar proton acceptor component of the surface energies and the respective hydration densities was proven for SLBs of pure lipids. We could show that the presence of PEG in the SLB produces a significant change of the proton acceptor component. Regarding the correlation between the surface energies and the hydration densities...

Supported lipid bilayers (SLBs) were prepared on glass and silicon slides grafted with polyethylene glycol (PEG) and covalently bound cholesteryl anchors to fix the lipid bilayer on the surface. Phospholipid bilayers and bilayers modified by addition of covalently bound PEG were investigated. Using contact angle measurements, the surface energy components of bilayer surfaces were analyzed using van Oss' and Owens-Wendt's methods. A quantitative correlation between the polar proton acceptor component of the surface energies and the respective hydration densities was proven for SLBs of pure lipids. We could show that the presence of PEG in the SLB produces a significant change of the proton acceptor component. Regarding the correlation between the surface energies and the hydration densities of SLBs with PEG, we were able to show a dependency on the PEG conformation. PMID:23084557

The layer-by-layer deposition of thin films of CdTe nanoparticles and three different polyelectrolytes has been investigated. Photoluminescence spectra were used to monitor the energy transfer properties within the films. As the number of bilayers in a thin film was increased a decrease in the energy of the light emitted was observed. The wavelength change is a two-stage process. Deposition of the first one to two bi-layers of a thin film produced a sharp energy change (626 nm to 637 nm with the addition of a single bi-layer) whereas deposition of subsequent bi-layers produced a more gradual energy change (642 nm-646 nm with the addition of 5 bi-layers). A space-filling mechanism is suggested to account for these changes; smaller nanoparticles penetrate the earlier levels of a thin film and increase the inter-particle energy transfer opportunities within the layers. PMID:18572687

Abstract Non-bilayer phospholipid arrangements are three-dimensional structures that can form when anionic phospholipids with an intermediate form of the tubular hexagonal phase II (HII), such as phosphatidic acid, phosphatidylserine or cardiolipin, are present in a bilayer of lipids. The drugs chlorpromazine and procainamide, which trigger a lupus-like disease in humans, can induce the formation of non-bilayer phospholipid arrangements, and we have previously shown that liposomes with non-bilayer arrangements induced by these drugs cause an autoimmune disease resembling human lupus in mice. Here we show that liposomes with non-bilayer phospholipid arrangements induced by Mn2++ cause a similar disease in mice. We extensively characterize the physical properties and immunological reactivity...

Today, it's hard to find dishwashing liquids or hand soaps that don't advertise their "antibacterial" chemicals. But while it's unclear whether these chemicals actually help us, there's new reason to believe they might do more harm than good. This Science Update examines the common antibacterial agent, Triclocarban or TCC, which is found in hand soaps and other household products.

...DEPARTMENT OF HEALTH AND HUMAN SERVICES...AND RELATED PRODUCTS ORAL DOSAGE...for sustained treatment of shipping...antibacterial product to obtain immediate...within 16 days of treatment; do not use...antibacterial product to obtain immediate...within 16 days of treatment; do not...

Acute bacterial sinusitis (ABS), acute exacerbations of chronic bronchitis (AECB), and community-acquired pneumonia (CAP) are common conditions and constitute a substantial socioeconomic burden. The ketolides are a new class of antibacterials with a targeted spectrum of antibacterial activity. In vi...

A series of novel N-acyl substituted quinolin-2(1H)-one derivatives were synthesized and screened in vitro for their antibacterial and antifungal activities by disc diffusion method. All the compounds exhibited moderate to good antimicrobial activities, some of these compounds displayed comparable or better antibacterial or antifungal activities against some tested strains compared to the reference drugs Streptomycin and Fluconazole.

Some hybrid 1,3,4-thiadiazole-1,3,5-triazine derivatives tethered via -S- bridge were synthesized and characterized with the aid of spectroscopic and elemental analysis. These hybrid conjugates were then investigated for their antibacterial activity against selected Gram-positive and Gram-negative bacteria. Excellent to moderate antibacterial activity was presented by the target compounds. PMID:22716235

Isolation procedures of two new acylphloroglucinols, myrtucommulone-A and myrtucommulone-B, from Myrtus communis leaves are given. Myrtucommulone-A was highly antibacterial against gram-positive bacteria but was not active against gram negatives. The chemical relation to other acylphloroglucinols and the antibacterial activity of the compounds isolated are discussed. PMID:15825301

Understanding the interactions of gold nanoparticles (AuNPs) with cellular compartments, especially cell membranes, is of fundamental importance in obtaining their control in biomedical applications. An effort is made in this paper to investigate the interactions of 2.2 nm core AuNPs with negative model bilayer membranes by coarse-grained (CG) molecular dynamics (MD) simulation. The CG model of lipid bilayer was taken from Marrink et al. ( J. Phys. Chem. B 2004, 108, 750-760 ), whereas the CG AuNPs model was developed on the basis of both atomistic MD simulations and experimental data. It was found that AuNPs functionalized with cationic ligands penetrated into the negative bilayer membranes and generated significant disruptions on bilayers. The lipids surrounding the nanoparticle were highly disordered and the bulk surface of the bilayer exhibits some defective areas. Most importantly, it is observed that a nanoscale hole can be formed and expanded spontaneously on the peripheral regions of the 20 × 20 nm bilayer. The expansion of the hole is on the time scale of hundreds of nanosceonds. The fully expanded hole had a radius of ?5.5 nm and could transport water molecules at a rate of up to ?1100 molecule/ns. However holes could not be formed on a larger bilayer (28 × 28 nm). The factors that can eliminate hole formation on the bilayer also include the decrease of cationic lignads on the AuNP, the reduction of negative lipids in the bilayer, the release of bilayer surface tension, the lowering of temperature, and the addition of a high concentration of salt. The results suggest that a hole can only be formed on living cell membranes under extreme conditions. PMID:21634406

This study aimed to optimize an extraction and separation procedure to obtain a concentrated fraction with antibacterial activity from the macroalga Ulva lactuca. Antibacterial compounds were extracted using eight solvents, and consistent activity against Staphylococcus aureus, Bacillus subtilis and methicillin-resistant (MR) S. aureus was observed from a dilute (1:100, w/v) ethyl acetate extract. Seasonal analysis revealed that antibacterial activity was the lowest in spring/summer and the highest in autumn/winter. Bioautography was found to be a more appropriate assay compared to disc diffusion when screening crude extracts, as it separates the masking compounds from the antibacterial compounds and a direct assessment of the bands responsible for the antibacterial effect could be made. T...

In continuing our program aimed to search for potent drugs for bacterial infections, a series of 3-(4-halophenyl)-3-oxopropanal and their derivatives were designed, synthesized and their antibacterial activities in vitro against both Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa were evaluated. Compounds 7, 8, 13—16, 21 and 22 had moderate antibacterial activities against Staphylococcus aureus (minimal inhibitory concentration (MIC) <16 ?g/ml), suggesting that the introduction of mono-methoxyamine or ethoxyamine moiety might play an important role in determining the potent antibacterial activities. Furthermore, the antibacterial activities of select compounds 7, 15 and 16 against the clinically important pathogenic bacteria-methicillin-resistant Staphylococcus aureus (MRSA) were also investigated. Results showed that these compounds exhibited more potent activities than the well-known antibacterial agents Houttuynin and Levofloxacin.   

Abstract The use of fabrics with antibacterial properties for commodity applications can provide numerous advantages such as a reduction in the release of odors due to bacterial proliferation in sweat and a reduction in the development of skin hypersensitivity reactions due to microorganisms trapped into the fabrics. Silver is one of the most effective antibacterial agents used for the high degree of biocompatibility and for its long-term antibacterial effectiveness against many different bacterial strains. In this study, an innovative technique for the deposition of nanosilver antibacterial coating on woolen fiber was analyzed. In particular, fabrics woven with different percentages of silver-treated fibers were compared to determine the best ratio preserving the antibacterial activity an...

A long-term-testing facility, the Integrated Corrosion Facility (I.C.F.), is being developed to investigate the corrosion behavior of candidate construction materials for high-level-radioactive waste packages for the potential repository at Yucca Mountain, Nevada. Corrosion phenomena will be characterized in environments considered possible under various scenarios of water contact with the waste packages. The testing of the materials will be conducted both in the liquid and high humidity vapor phases at 60 and 90{degrees}C. Three classes of materials with different degrees of corrosion resistance will be investigated in order to encompass the various design configurations of waste packages. The facility is expected to be in operation for a minimum of five years, and operation could be extended to longer times if warranted. A sufficient number of specimens will be emplaced in the test environments so that some can be removed and characterized periodically. The corrosion phenomena to be characterized are general, localized, galvanic, and stress corrosion cracking. The long-term data obtained from this study will be used in corrosion mechanism modeling, performance assessment, and waste package design. Three classes of materials are under consideration. The corrosion resistant materials are high-nickel alloys and titanium alloys; the corrosion allowance materials are low-alloy and carbon steels; and the intermediate corrosion resistant materials are copper-nickel alloys.

In hydrometallurgy, the reactive liquid/liquid extraction technique is mainly used in heavy metal elimination after ore leaching, in the preparation of rare earths, and in metal recovery from process solutions. In the latter application, using complexing tensides which are soluble in oil, the metals are converted into an organic phase. From this they are concentrated in a strongly acidic phase by a reextraction step.- The object of this work was to separate the four heavy metals copper, nickel, zink and cadmium from the reextraction acid by means of an electrochemical process and to eliminate them selectively. The reextraction acid is used again in the extraction process. (orig.) [Deutsch] In der Hydrometallurgie findet das Verfahren der reaktiven fluessig/fuessig Extraktion vorwiegend Anwendung zur Schwermetallabtrennung nach einer Erzlaugung, zur Darstellung Seltener Erden, sowie bei der Metallrueckgewinnung aus Prozessloesungen. Hierbei werden die Metalle mit Hilfe von oelloeslichen komplexbildenden Tensiden in eine organische Phase ueberfuehrt, aus der sie dann durch einen Reextraktionsschritt in einer stark sauren Phase aufkonzentriert werden. Aufgabe der vorliegenden Arbeit war es, mit Hilfe eines elektrochemischen Verfahrens die vier Schwermetalle Kupfer, Nickel, Zink und Cadmium aus der Reextraktionssaeure abzutrennen und elektrochemisch selektiv abzuscheiden. Die Reextraktionsaeure sollte dann wieder in den Extraktionsprozess zurueckgefuehrt werden. (orig.)

In this study, dispersive liquid-liquid microextraction (DLLME) combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed for simultaneous preconcentration and trace determination of chromium, copper, nickel and zinc in water samples. Sodium diethyldithiocarbamate (Na-DDTC), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. The effective parameters of DLLME such as volume of extraction and disperser solvents, pH, concentration of salt and concentration of the chelating agent were studied by a (2(f-1)) fractional factorial design to identify the most important parameters and their interactions. The results showed that concentration of salt and volume of disperser solvent had no effect on the extraction efficiency. In the next step, central composite design was used to obtain optimum levels of effective parameters. The optimal conditions were: volume of extraction solvent, 113 ?L; concentration of the chelating agent, 540 mg L(-1); and pH, 6.70. The linear dynamic range for Cu, Ni and Zn was 1-1000 ?g L(-1) and for Cr was 1-750 ?g L(-1). The correlation coefficient (R(2)) was higher than 0.993. The limits of detection were 0.23-0.55 ?g L(-1). The relative standard deviations (RSDs, C=200 ?g L(-1), n=7) were in the range of 2.1-3.8%. The method was successfully applied to determination of Cr, Cu, Ni and Zn in the real water samples and satisfactory relative recoveries (90-99%) were achieved. PMID:21147333

One waste-treatment method that advanced in the wake of the Resource Conservation and Recovery Act`s land-disposal restrictions--cement-based solidification and stabilization technology--rests on a concrete premise. Calcium hydroxide and calcium silicate hydrate formed during hydration of portland cement have chemical and physical properties that can safely stabilize hazardous compounds and solidify the varied waste forms in which they occur. Due to the complexity of waste streams, cement-based solidification-stabilization offers no single recipe for all wastes and conditions, and its precise chemical reactions have yet to be determined. However, reports from the federal government, waste generators and treaters underscore the utility of portland cement as a reagent for stabilizing and solidifying waste. Like most solidification systems, cement-based treatment economically eliminates free liquids, reduces hazardous constituent mobility by lowering waste permeability, minimizes constituent leachability, and provides physical stability for handling, transport and disposal. Inorganic wastes amenable to cement-based stabilization include: arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, copper, nickel, and zinc.

Evaluating spatial and temporal trends in contaminant residues in Puget Sound fish and macroinvertebrates are the objectives of the Puget Sound Ambient Monitoring Program (PSAMP). In a cooperative effort between the ENVironmental inVESTment group (ENVVEST) and Washington State Department of Fish and Wildlife, additional biota samples were collected during the 2007 PSAMP biota survey and analyzed for chemical residues and stable isotopes of carbon (?13C) and nitrogen (?15N). Approximately three specimens of each species collected from Sinclair Inlet, Georgia Basin, and reference locations in Puget Sound were selected for whole body chemical analysis. The muscle tissue of specimens selected for chemical analyses were also analyzed for ?13C and ?15N to provide information on relative trophic level and food sources. This data report summarizes the chemical residues for the 2007 PSAMP fish and macro-invertebrate samples. In addition, six Spiny Dogfish (Squalus acanthias) samples were necropsied to evaluate chemical residue of various parts of the fish (digestive tract, liver, embryo, muscle tissue), as well as, a weight proportional whole body composite (WBWC). Whole organisms were homogenized and analyzed for silver, arsenic, cadmium, chromium, copper, nickel, lead, zinc, mercury, 19 polychlorinated biphenyl (PCB) congeners, PCB homologues, percent moisture, percent lipids, ?13C, and ?15N.

The Minerals Division of the Minnesota Department of Natural Resources (DNR) has been conducting reclamation research jointly funded by the State and industry for many years. This cooperative program began with AMAX Exploration Company in the mid-1970`s at the Minnamax copper-nickel exploration site near Babbitt, Minnesota. During the ensuing years, many projects, with a wide range of purposes, have been undertaken with the cooperation of numerous mining and exploration companies and government agencies. These activities eventually led to the Minnesota Legislature establishing the Minerals Cooperative Environmental Research fund in 1993 and the construction of the Mine Waste and Reclamation Research site at Hibbing, Minnesota in 1995. The types of cooperative projects undertaken are directed either at the needs of the existing mining operations in Minnesota or address mineral deposits that may be mined here in the future. Mining studies have looked at ways to lower costs and improve the effectiveness of reclamation. Projects directed at potential future mining have focused on predicting if mine waste leachate will produce water quality problems, as well as methods to reclaim mine wastes with an emphasis on lowering long term maintenance costs. It has been the authors` experience that by working on jointly funded projects in partnerships with other groups that several benefits result including: the projects that are selected are of practical interest to the partners; a good understanding of individual participant needs and goals are obtained; and, the results are more readily accepted and implemented by all parties involved.

Fiber optic sensors offer several advantages over their electrical counterparts, especially for applications in hostile, spark-sensitive environments, because no electrical power is required at the sensors. In addition, the installation of fiber sensors external to fluid carrying conduits facilitates access for troubleshooting and replacement, unlike in-line diaphragm-based sensors. Furthermore, glass fiber pressure sensors have a much higher operating temperature range, which makes them more practical for flammability-prone environments. Multiple fiber Bragg grating (FBG) sensors can be multiplexed along a single fiber optic cable, as opposed to traditional resistive strain gauges, which require individual shielded metal cabling. Applications for such fiber-optic pressure detection systems include the pressure monitoring of flow in fuel lines and their pressure valves. This paper characterizes the application of FBG sensors, with remote access capability, for the nonintrusive pressure monitoring of different types of metallic pipes. We show that pressure changes smaller than one psi can be detected with a tunable diode laser-based detection system. Standard metal pipes of steel, inconel, copper-nickel alloy and titanium are characterized, and the resilience of FBG sensors to an overpressure of up to 1500 psi is demonstrated.

Muja is a 1040 MW inland power station in the south west of Western Australia. Groundwater is used in the recirculating cooling system for the four 60 MW and four 200 MW turbines. A project team was formed to evaluate the condition of all condensers and to investigate the cause of the pitting corrosion. As a result of this project, unit 8 of the Muja has been re-tubed with 90/100 copper nickel and unit 7 will be re-tubed within the next few years. This paper details the investigation of the causes of the tube corrosion. It also deals the water management plan which was developed to control the parameters causing corrosion and fouling of condensers. Chemical dosing and extensive monitoring of the Unit 7 and 8 cooling system has been instigated. A number of Key Performance Indicators have been selected, and the operation of the system is reviewed monthly. The initial success of this strategy has prompted management to consider a similar program for the other units at Muja. (author). 4 tables. 5 refs.

The properties of sliding metal interfaces under dynamic loading conditions are poorly known. For regimes of sliding speeds of order 0.1 the transverse sound speed and pressures of order shock pressures in metals, the following are essentially open questions from both a theoretical and experimental perspective: the velocity dependence of the tangential force, the nature of surface and subsurface micro structure and dislocation structure and evolution. Experimentally, there has been some recent progress in pressure-shear geometries by Prakash and Clifton for elastic materials. Theoretically, Sokoloff has treated a simplified model for which an inverse velocity dependence for g, the coefficient of sliding friction, has been predicted. In lieu of experimental work and as an incentive to perform relevant experiments it is of interest to perform numerical experiments. Of particular relevance are molecular dynamics (MD) experiments for materials with well characterized density dependent interatomic interaction potentials. For ductile metals (e.g., copper, nickel, aluminum), such potentials exist and are capable of reproducing equations of state and defect properties have shown. We shall present here the results of a series of atomistic simulations for copper-copper interfaces in a two dimensional geometry, focusing mainly on the density and velocity dependence of the coefficient of friction.

The metal mining industry faces extraordinary challenges to become environmentally sustainable. The use of non-photosynthetic organisms alone to describe environmental impact has been recognized by regulatory agencies, industry and academia as being totally inadequate both in Europe and North America. The lack of adequate testing methods are of even more concern to the metal mining industry due to non-biodegradable nature of its waste streams. The authors are developing new and assessing old aquatic phytotoxicity testing methods. They expect this will result in: (1) rapid and sensitive photosynthetic screening tools for the assessment of environmental hazard of on-site effluents both in freshwater in marine environments; (2) environmental relevance by including phytoplankton, submergent and emergent macrophytes, and marine macrobenthic algae; and (3) risk assessment improvements for different categories of wastes and toxicity modifications caused by various environmental factors. Preliminary data from this work show that the chemical effluent limits set in the ``Metal mining liquid effluent regulations`` (1977) provide variable protection of aquatic photosynthetic organisms and aquatic effects of the more toxic metals, copper, nickel, and zinc, may occur at levels that are one to two orders of magnitude lower than present limits. To establish adequate protection of receiving water bodies it may be necessary to establish site-specific criteria taking into consideration toxicity modifying factors of individual sites. If the establishment of such criteria is determined with a host of ecologically relevant organisms, it will be possible to design effective environmental protection at the least possible cost.

Soils of the Pampas show no signs of contamination with potentially toxic elements (PTEs), except in the areas that surround cities. The concentration of PTE in crops grown in this region is in most cases unknown. Our objective was to determine the PTE concentration in main field crops and pastures grown in 'a priori' non-contaminated areas and in potentially contaminated areas around cities. Forty-eight plots from farms located far from cities or roads and 36 plots from farms located very close to cities or to high traffic roads were sampled. The area ranged from 33 degrees 40' S to 36 degrees 0' S and from 57 degrees 35' W to 61 degrees 22' W. Maize, soybean, wheat, grazed grassland and pastures, and their top soils were sampled. All samples were acid digested. Cadmium, zinc, chromium, copper, nickel and lead were determined using ICPES. Standard t-tests were performed. All soils were within the known normal values of soil PTE concentrations, with the exception of a few cases around cities. PTE accumulation on grains and aerial biomass is considered almost negligible in crops grown in both studied areas, with the exception of a few elements in soybean. PTE concentrations in crops and pastures are in keeping with the low content of trace metals found in soils of the Pampas. PMID:16356625

Argonne National Laboratory has been responsible for the technical management of the OTEC Biofouling, Corrosion, and Materials Program since March 1978. By March of 1981, sensitive field-usable heat-transfer monitors had been developed, extensive open ocean testing had been done, a considerable understanding of the microbiofouling problem had been developed, and commercial methods of removal had been shown to be effective. As a material of construction for heat exchangers, titanium showed excellent corrosion resistance. New grades of stainless steel also showed excellent corrosion resistance, while the most common grades suffered from pitting and/or crevice corrosion. The best aluminum alloys and Alclads showed no pitting and moderate declining corrosion rates under optimum conditions in warm seawater, but were subject to accelerated attack from stagnant water, crevices, abrasive treatment, and ammoniated water; in cold seawater, limited data showed very good behavior. Copper-nickel alloys were similar to aluminum alloys in corrosion rate and were subject to accelerated attack from the same factors; ammonia had a particularly severe effect on these alloys.

An effort to develop licensable engineered barrier systems for the long-term (about 1000 yr) containment of nuclear wastes under conditions of deep continental geologic disposal has been underway at Pacific Northwest Laboratory since January 1979, under the auspices of the High-Level Waste Immobilization Program. In the present work, the barrier system comprises the hard or structural elements of the package: the canister, the overpack(s), and the hole sleeve. A number of candidate metallic, ceramic, and polymeric materials were put through mechanical, corrosion, and leaching screening tests to determine their potential usefulness in barrier-system applications. Materials demonstrating adequate properties in the screening tests will be subjected to more detailed property tests, and, eventually, cost/benefit analyses, to determine their ultimate applicability to barrier-system design concepts. The following materials were investigated: two titanium alloys of Grade 2 and Grade 12; 300 and 400 series stainless steels, Inconels, Hastelloy C-276, titanium, Zircoloy, copper-nickel alloys and cast irons; total of 14 ceramic materials, including two grades of alumina, plus graphite and basalt; and polymers such as polyamide-imide, polyarylene, polyimide, polyolefin, polyphenylene sulfide, polysulfone, fluoropolymer, epoxy, furan, silicone, and ethylene-propylene terpolymer (EPDM) rubber. The most promising candidates for further study and potential use in engineered barrier systems were found to be rubber, filled polyphenylene sulfide, fluoropolymer, and furan derivatives.

Turnover rates for the catalytic dehydrogenation and dehydration of formic acid (HCOOH) on nickel/silica (Ni/SiO/sub 2/) and Ni and copper-nickel (CuNi) powders between 390 and 490 K are reported. The decomposition rate constants calculated from these data are compared with values reported previously for the temperature-programmed decomposition (TPD) of HCOOH preadsorbed on Ni and CuNi. Catalytic dehydrogenation and dehydration seem to proceed through the same intermediate, believed to be a formate ion. The selectivity S, defined as the ratio of dehydrogenation to dehydration turnover rates, is independent of temperature, and between 4 and 6 on Ni and alloys with a surface Cu fraction less than 0.8. The observed selectivity is not affected by secondary reactions among the products. The intermediate appears to be bound to two adjacent Ni atoms. In contrast, TPD or HCOOH preadsorbed at low coverage on CuNi single crystals seems to involve a formic anhydride species that requires four adjacent Ni atoms, and decomposes with S equal to unity and a rate constant 5 x 10/sup 3/ times greater than that corresponding to the catalytic decomposition. This study demonstrated the differences in rate constant and S when reactive intermediates change with surface coverage because they require different ensembles for adsorption; in other words, they are structure sensitive.

Porous particles of oxides of transitional metals, such as copper, nickel, cobalt, iron, manganese, and chromium, were prepared in single and binary mixtures by the freeze-drying process to serve as combustion catalysts. Aqueous metal sulfate solutions of the above metals were utilized as raw material for freeze-drying. Spherical drops of the solutions were instantly frozen in a cooled bath. The frozen particles were dried in a vacuum chamber. These were then calcined into particles of single and double oxides, as well as oxide mixtures. The open porosity within the freeze-dried particles induced by sublimation of ice crystals was retained during calcination and the subsequent firing. Methane/air was combusted in an adiabatic tubular reactor in the presence of the porous oxide particles to determine the particles’ catalytic activity. The feed gas equivalence ratio and residence time were kept constant while methane conversions were measured as a function of gas temperature. The activity of the catalysts was assessed based on the temperature during the surface-kinetics-controlled regime. Among the catalysts examined, the strongest were binary oxides of cobalt and nickel.   

Application of two-phase closed thermosiphons to heat recovery systems has led the authors to investigate the performance of thermosiphons at medium temperatures. Two-phase closed thermosiphons working under various conditions have been tested and their thermal performance has been measured for mean evaporator wall temperatures between 100{sup o}C and 250{sup o}C. A description of the design and construction of the test facility is included. Aspects of safety of container materials have been investigated for water as the working fluid. It was found that copper-nickel alloys and carbon-manganese stainless steel are suitable container materials for the range of temperatures considered. The critical heat flux and dry-out limit were observed in experiments with a 13.2 mm diameter thermosiphon. Boiling heat transfer phenomena and overall thermal conductance have been experimentally investigated. It was found that an increase in thermosiphon diameter changes the boiling mechanism from saturated film boiling to nucleate boiling. The test results show a good agreement with published correlation criteria. Further experiments are needed to determine the optimum pipe diameter for the applications under consideration. (Author)

An organofunctionalized mesoporous HMS-like compound has been synthesized by reacting the silylating agent 3-glycidoxypropyltrimethoxysilane with gaseous ammonia. The reaction path leads to the opening of the three membered epoxide ring to incorporate ammonia to give the modified silylating agent. This new silylating agent was used to synthesize a mesostructure inorganic-organic hybrid through the neutral template directing agent, dodecylamine, using a co-condensation process, and exploring the ability of the silicon source tetraethoxysilane. The final solid named HMS-NH has been characterized through elemental analysis, X-ray powder diffraction, nitrogen gas adsorption, infrared spectroscopy and solid state NMR for the 29Si nucleus. An amount of 1.06+/-0.10 mmol of pendant groups is covalently bonded to the inorganic backbone. The attached basic centers adsorbed divalent cations to give the maxima adsorption capacity of 0.74+/-0.03, 0.55+/-0.06, 0.53+/-0.05 and 0.51+/-0.06 mmolg(-1) for copper, nickel, zinc and cobalt, respectively. From calorimetric determinations the quantitative thermal effects for all these cation/basic center interactions gave exothermic enthalpy, negative Gibbs free energy and positive entropy. These thermodynamic data confirmed the energetically favorable condition of such interactions at the solid/liquid interface for all systems. PMID:17707390

Column outflow experiments operated at steady state flow conditions do not allow the identification of rate limited release processes. This requires an alternative experimental methodology. In this study, the aim was to apply such a methodology in order to identify and quantify effective release rates of heavy metals from granular wastes. Column experiments were conducted with demolition waste and municipal waste incineration (MSWI) bottom ash using different flow velocities and multiple flow interruptions. The effluent was analyzed for heavy metals, DOC, electrical conductivity and pH. The breakthrough-curves were inversely modeled with a numerical code based on the advection-dispersion equation with first order mass-transfer and nonlinear interaction terms. Chromium, Copper, Nickel and Arsenic are usually released under non-equilibrium conditions. DOC might play a role as carrier for those trace metals. By inverse simulations, generally good model fits are derived. Although some parameters are correlated and some model deficiencies can be revealed, we are able to deduce physically reasonable release-mass-transfer time scales. Applying forward simulations, the parameter space with equifinal parameter sets was delineated. The results demonstrate that the presented experimental design is capable of identifying and quantifying non-equilibrium conditions. They show also that the possibility of rate limited release must not be neglected in release and transport studies involving inorganic contaminants. PMID:18757112

Trace element levels in nine different dried fruit samples from Kayseri, Turkey were determined by flame atomic absorption spectrometry after dry and wet digestion methods. Good accuracy was assured by the analysis of standard reference material (NIST-SRM 1515-Apple Leaves). The contents of trace elements in the samples were determined in the ranges of 1.68-4.52, 0.6-9.4, 5.5-12.4, 6.76-64.1, 4.74-25.5, 0.2-1.78, 0.8-6.17 and 0.1-0.81 microg/g for copper, nickel, lead, iron, manganese, cobalt, chromium and cadmium, respectively. The highest copper content was 4.52 microg/g in black grape, highest nickel content was 9.4 microg/g in black plum, highest lead content was 12.4 microg/g in apricot, highest iron content was 64.1 microg/g in apricot, highest manganese content was 25.5 microg/g in rose hip, highest cobalt content was 1.81 microg/g in white mulberry, highest chromium content was 6.17 microg/g in yellow plum and highest cadmium content was 0.8 microg/g in apricot and rose hip. The results were compared with the literature values. PMID:18991103

Corrosion evaluations were conducted on 3003 Alclad, C70600 copper-nickel, and commercially-pure titanium in natural seawater under simulated OTEC heat exchanger conditions to investigate the erosion-corrosion effects of mechanical tube cleaning under aggressive over-cleaning conditions. Test conditions for 3003 Alclad included Amertap soft sponge ball cleaning with and without chlorination. Amertap abrasive sponge ball cleaning with and without chlorination, and no mechanical cleaning as a control. C70600 was exposed to Amertap soft sponge ball cleaning with and without chlorination and with no mechanical cleaning as a control. Titanium was cleaned by abrasive Amertap sponge balls with and without chlorination and compared to no mechanical cleaning as a control. Test exposures of 8, 16, 30, 60, 90 and 180 days were made. The sequence of Amertap sponge ball cleaning utilized in the present tests significantly accelerated corrosion of 3003 Alclad. Chlorination brought about a further acceleration of erosion-corrosion of Alclad. Amertap soft sponge ball cleaning of C70600 caused significant acceleration of corrosion under these over-cleaning conditions. Chlorination somewhat decreased erosion corrosion of C70600. Titanium showed no substantial effect of Amertap abrasive sponge ball cleaning on corrosion, although measurable weight losses were incurred. Chlorination had no measurable effect on erosion-corrosion of titanium.

EPORA (Effects of Industrial Pollution on Distribution Dynamics of Radionuclides in Boreal Understorey Ecosystems) is part of the EU Nuclear Fission Safety Programme 1994-1998, and is co-ordinated by STUK. The main purpose of the project is to study the influence of strong chemical pollution on the turnover of long-lived artificial radionuclides in a northern boreal ecosystem, and its implication on the radiation exposure to local population. The study area is located in the Kola peninsula, Russia in the vicinity of the Monchegorsk copper-nickel smelter. The smelter has operated since 30's and has since then discharged large amounts of sulphur and heavy metals into its surroundings.The present report is a documentation of the chemical analyses of soils and vegetation performed in EPORA in order to characterize the ecological impact of the emissions from Monchegorsk at different distances from the smelter. It also contains a brief description of the methods used and a summary of the most prominent trends apparent from the data presented. (orig.)

Heavy metals are widely recognized as highly toxic and dangerous. Past research activities on heavy metal pollution in Hong Kong have emphasized coastal environmentals. Since the main sources of heavy metals are the discharge and spillage of wastewater from electroplating factories, concentrations of heavy metals in streams and pools near industrial areas may be higher than those in coastal waters. Electroplating wastewater in Hong Kong contains high levels of chromium, copper, nickel and zinc. The toxicity of these heavy metals to the aquatic organisms has been extensively reviewed. Toxicity information for invertebrates shows that crustaceans are among the most sensitive organisms. Of the crustacean species tested, cladocerans appear to be the most susceptibile. Cladocerans are important components of many aquatic ecosystems. Despite their importance in many freshwater communities and their sensitivity to heavy metal toxicity, information on the toxicity of heavy metals to cladocerans is limited except for several Daphnia species. In Hong Kong the freshwater cladoceran Moina macrocopa occurs in small ponds and rice paddies and is mass cultured by some farmers as a high quality fish food. The objectives of this study are to determine the effects of various heavy metals on the survival and feeding of M. macrocopa. 12 refs., 2 figs., 1 tab.

This report summarizes results of recent analyses of heavy metals in fish from Savannah River Site (SRS) streams near the F-Area and H-Area seepage basins. Fish were collected from headwater areas of Four Mile Creek and Pen Branch, from just below the H-Area seepage basin, and from three sites downstream in Four Mile Creek. These fish were analyzed for RCRA trace metals using standard EPA methods. Silver, arsenic, beryllium, cadmium, copper, nickel, lead, antimony, and thallium were all either undetectable or had only a few detectable values. Mercury values were all well below the regulatory limit of 1 {mu}g/g. For the total group of fish analyzed, there were no differences among sampling site for aluminum, chromium, or zinc. Selenium concentrations differed among sites, with fish collected near the H-Area and two control sites having the highest concentrations. When selenium concentrations were compared across sunfishes only, the seepage basin site was shown to be slightly elevated. Among species, yellowfin shiners had higher aluminum and zinc concentrations than sunfishes and bottom fish. 24 refs.

The effects of storage in the presence of copper using laboratory test conditions vs field conditions on fuel thermal stability were compared using five JP-5 fuels. Laboratory test conditions refer to accelerated storage at 90{degree}C/50 psig of air/24 h in the presence of soluble copper from copper(II) ethyl acetoacetate (CuEA). In contrast, field conditions refer to long-term storage at room temperature in the presence of dissolved copper from 90/10 copper-nickel (Cu-Ni) alloy for a period of approximately 6 months. Thermal stabilities were determined using the gravimetric JFTOT, which gives a quantitative measure of the total deposits formed. A copper concentration/storage effect was observed, which necessitated evaluations at similar copper concentrations. However, the source of copper appears not to be important. Instead, the main operative factor affecting the thermal stability of stored fuels appears to be the combination of long-term ambient storage and the presence of copper. Good agreement was obtained between the thermal stabilities of fuels that were stored using the specified laboratory and field conditions. These results are significant because (1) they validate the use of the specified laboratory test conditions as being realistic; (2) they support the premise that precursors that lead to thermal deposits are formed on storage in the presence of copper; and (3) they offer a rigorous method for predicting the potential thermal stability of jet fuels. 15 refs., 2 figs., 7 tabs.

The present work is intended to offer the reader a comprehensive survey of the literature on mosses as biological indicators of heavy metal emissions. It presents a choice of the most important contributions and papers on this subject and thus summarizes the present state of knowledge and research on plants as biological indicators (as exemplified by mosses) in the different countries. The volume also presents original papers dealing not only with the typical heavy metals such as lead, cadmium, chromium, beryllium, copper, nickel, mercury and vanadium, but also with other metals and elements such as uranium, cesium and alkaline metals as well as alkaline-earth metals. In most cases, the original papers have been translated, abstracted, or summarized to give the essential ideas and results. An unusually extensive bibliography at last provides further information on publications on the subject. Moreover, a selection of experimental papers is given at the end of the book. This was done to illustrate the need for experimental investigations verifying or substantiating the ecological information to be gained from biological indicators.

Specific elements are bioconcentrated in human hair and nails, which have unique advantages of application in population monitoring studies thereby, recognized as biological tools for disease diagnosis and prevention. However, investigations are meager for relative element profile in hair and nails of same subjects. In this study, hair and nails were analyzed to find effects of age, sex, smoking habit, diet, urban and rural exposure gradients, occupation, and health on element levels. Scalp hair and fingernails were sampled along with a questionnaire from urban and rural subjects of New Delhi; patients of hypertension, coronary heart disease, and diabetes were identified clinically. Cadmium, chromium, copper, nickel, lead and zinc concentrations were determined by AAS in both the samples; CRM (human hair powder) analysis showed acceptable precision and accuracy in element measurement. In comparison to controls, Cr-H and Zn-H levels were lower respectively in female hypertensive and total hypertensive subjects, whereas, Zn-N and Cu-N were lower respectively in total CHD and diabetic subjects, and hypertensive and CHD urban subjects. Cd concentrations were higher in both the samples of tobacco smoking rural subjects than that of non-smokers. Farmers had lower Pb-H than rural businessmen did. Cr, Cu, Ni, and Zn concentrations were different due to rural and urban gradient but not to the influence of age, sex, and diet. Pb value was alone correlated between the paired samples. Thus, higher Cd levels in the smokers and lower Cr, Cu and Zn levels in the patients were observed.

Dietborne metal uptake prevails for many species in nature. However, the links between dietary metal exposure and toxicity are not well understood. Sources of uncertainty include the lack of suitable tracers to quantify exposure for metals such as copper, the difficulty to assess dietary processes such as food ingestion rate, and the complexity to link metal bioaccumulation and effects. We characterized dietborne copper, nickel, and cadmium influxes in a freshwater gastropod exposed to diatoms labeled with enriched stable metal isotopes. Metal influxes in Lymnaea stagnalis correlated linearly with dietborne metal concentrations over a range encompassing most environmental exposures. Dietary Cd and Ni uptake rate constants (kuf) were, respectively, 3.3 and 2.3 times higher than that for Cu. Detoxification rate constants (k detox) were similar among metals and appeared 100 times higher than efflux rate constants (ke). Extremely high Cu concentrations reduced feeding rates, causing the relationship between exposure and influx to deviate from linearity; i.e., Cu uptake rates leveled off between 1500 and 1800 nmol g-1 day-1. L. stagnalis rapidly takes up Cu, Cd, and Ni from food but detoxifies the accumulated metals, instead of reducing uptake or intensifying excretion. Above a threshold uptake rate, however, the detoxification capabilities of L. stagnalis are overwhelmed.

This research demonstrated the impact of high densities of the zebra mussel (Dreissena polymorpha) on the cycling of copper, nickel, and zinc in a lake environment. Experiments with mussels on sedimentation traps in western Lake Erie and with mussels in flow-through tanks receiving Lake Erie water showed that zebra mussels remove metals from the water column, incorporate metals in their tissues, and deposit metals on the lake bottom. Removal of metals from the water column was estimated at 10-17%{center_dot}day{sup -1} of the amounts present. This material was largely deposited on the lake bottom; zebra mussels more than doubled the rate at which metals were being added to the lake bottom. Metal biodeposition rates were extremely high (e.g., 50 mg Zn{center_dot}m{sup -2}{center_dot}day{sup -1}) in high-turbidity areas with elevated metal levels. Two factors contributed to metal biodeposition by zebra mussels. First, their production of feces and pseudofeces increased the rate at which suspended matter was being added to the sediment (accounting for 92% of the increased metal biodeposition). Second, the material coming out of suspension had higher metal concentrations when zebra mussels were present (constituting 8% of the increased biodeposition). (author)

In elektrolytic copper refining the electrolyte concentrates with copper, nickel, arsenic and antimony during the electrolyzing process. To purify the electrolyte, copper, arsenic and antimony are precipitated by electrolytic decopperizing. Some of the arsenic content is reduced to highly toxic arsine, usually in a time-limited process. Theoretical and systematic experimental investigations were made with regard to the influence of certain electrolysis parameters on the arsine mass obtained and to the different reaction steps on the cathode. First by means of decopperizing the deposition of copper takes place and then by smaller copper concentrations the deposition of copperarsenides (Cu/sub 3/As, Cu/sub 5/As/sub 2/ e.g.). These are the principal reactions of the process. In the same potential range antimony and a small part of nickel are also reduced. - Arsine is formed by the reduction of dissolved arsenic from electrolyte with low copper contents and not by the reduction of elementary arsenic or copperarsenides. The cathodic reduction of As(V) is more inhibited than that of As(III). Therefore under the same conditions the deposition of As(III) is faster and the arsine mass formed smaller. - The best conditions for minimizing of arsine formation are the common deposition of copper and arsenic to copperarsenides, and with higher contents of arsenic in the electrolyte the chemical reduction of As(V) to As(III) before decopperizing takes place.

Oxidative UV photolysis according to DIN standard 38406 E 16 has been investigated as a sample preparation method for voltammetry. UV photolysis has decisive advantages compared with mineral acid digestion owing to the simple procedure and the very low blank values, which in turn are due to the minimal reagent addition required. For UV photolysis with a high pressure mercury lamp, an apparatus has been used that employs a new type of sample cooling and that allows the simultaneous irradiation of 12 samples. The sample preparation for the voltammetric determination of zinc, cadmium, lead, copper, nickel and cobalt has been optimized using a model water solution and subsequently tested with real matrices. The type of organic matrix and the irradiation temperature determine the irradiation time required. To digest aromatic compounds, it is advantageous to work at reaction temperatures of ca. 90deg C. The application of UV photolysis centers on water samples slightly polluted with organic compounds; however, it can also be used with more heavily polluted waste waters. As the digestion times are at most 60 min, the method is of interest for routine analysis. (orig.).

For many decades, copper-nickel alloy CuNi 90/10 (UNS C70600) has extensively been used as a piping material for seawater systems in shipbuilding, offshore, and desalination industries. Attractive characteristics of this alloy combine excellent resistance to uniform corrosion, remarkable resistance to localised corrosion in chlorinated seawater, and higher erosion resistance than other copper alloys and steel. Furthermore, CuNi 90/10 is resistant to biofouling providing various economic benefits. In spite of the appropriate properties of the alloy, instances of failure have been experienced in practice. The reasons are mostly attributed to the composition and production of CuNi 90/10 products compounds, occurrence of erosion-corrosion and corrosion damage in polluted waters. This paper covers important areas which have to be considered to ensure successful application of the alloy for seawater tubing. For this purpose, the optimum and critical operating conditions are evaluated. It includes metallurgical, design and fabrication considerations. For the prevention of erosion-corrosion, the importance of hydrodynamics is demonstrated. In addition, commissioning, shut-down and start-up measures are compiled that are necessary for the establishment and re-establishment of the protective layer. (author)

Despite significant efforts and promising progress, the understanding of membrane protein folding lags behind that of soluble proteins. Insights into the energetics of membrane protein folding have been gained from biophysical studies in membrane-mimicking environments (primarily detergent micelles). However, the development of techniques for studying the thermodynamics of folding in phospholipid bilayers remains a considerable challenge. We had previously used thiol-disulfide exchange to study the thermodynamics of association of transmembrane -helices in detergent micelles; here, we extend this methodology to phospholipid bilayers. The system for this study is the homotetrameric M2 proton channel protein from the influenza A virus. Transmembrane peptides from this protein specifically self-assemble into tetramers that retain the ability to bind to the drug amantadine. Thiol-disulfide exchange under equilibrium conditions was used to quantitatively measure the thermodynamics of this folding interaction in phospholipid bilayers. The effects of phospholipid acyl chain length and cholesterol on the peptide association were investigated. The association of the helices strongly depends on the thickness of the bilayer and cholesterol levels present in the phospholipid bilayer. The most favorable folding occurred when there was a good match between the width of the apolar region of the bilayer and the hydrophobic length of the transmembrane helix. Physiologically relevant variations in the cholesterol level are sufficient to strongly influence the association. Evaluation of the energetics of peptide association in the presence and absence of cholesterol showed a significantly tighter association upon inclusion of cholesterol in the lipid bilayers.

Lipid bilayers with a controlled content of anionic lipids are a prerequisite for the quantitative study of hydrophobic-electrostatic interactions of proteins with lipid bilayers. Here, the asymmetric distribution of zwitterionic and anionic lipids in supported lipid bilayers is studied by neutron reflectometry. We prepare POPC/POPS (3:1) unilamellar vesicles in a high-salt-concentration buffer. Initially, no fusion of the vesicles to a SiO(2) surface is observed over hours and days. Once the isotonic buffer is exchanged with hypotonic buffer, vesicle fusion and bilayer formation occur by osmotic shock. Neutron reflectivity on the bilayers formed this way reveals the presence of anionic lipids (d(31)-POPS) in the outer bilayer leaflet only, and no POPS is observed in the leaflet facing the SiO(2) substrate. We argue that this asymmetric distribution of POPS is induced by the electrostatic repulsion of the phosphatidylserines from the negatively charged hydroxy surface groups of the silicon block. Such bilayers with controlled and high contents of anionic lipids in the outer leaflet are versatile platforms for studying anionic lipid protein interactions that are key elements in signal transduction pathways in the cytoplasmic leaflet of eukaryotic cells. PMID:22789026

We have investigated the effect of chemical state control of the Si substrate surfaces for the formation of low-defective uniform supported lipid bilayers. To form supported lipid bilayers, we used the vesicle fusion method. In the bilayer formation processes, control of the interfaces between the vesicles and the surfaces is important. To examine the effect of the oxide formation process on Si surfaces, we used SiO2 surfaces prepared by chemical acid-treatment and those by thermal oxidation. SiO2 surfaces are generally hydrophilic. To change the chemical state of the SiO2 surfaces, they were modified with various self-assembled monolayers. These surfaces were immersed in a solution with lipid vesicles suspension, and the lipid vesicles were transformed into planar bilayers. The hydrophilic surface is more suitable for the uniform lipid bilayer formation than the hydrophobic surface. The bilayer coverage on the thermal oxide surface is larger than that on the chemical oxide one. These results indicate that the surface chemical states influence the efficiency of the supported lipid bilayer formation. [DOI: 10.1380/ejssnt.2007.99]   

Water permeability of two different lipid bilayers of dipalmitoylphosphatidylcholine (DPPC) and palmitoylsphingomyelin (PSM) in the absence and presence of cholesterol (0-50 mol %) have been studied by molecular dynamics simulations to elucidate the molecular mechanism of the reduction in water leakage across the membranes by the addition of cholesterol. An enhanced free energy barrier was observed in these membranes with increased cholesterol concentration, and this was explained by the reduced cavity density around the cholesterol in the hydrophobic membrane core. There was an increase of trans conformers in the hydrophobic lipid chains adjacent to the cholesterol, which reduced the cavity density. The enhanced free energy barrier was found to be the main reason to reduce the water permeability with increased cholesterol concentration. At low cholesterol concentrations the PSM bilayer exhibited a higher free energy barrier than the DPPC bilayer for water permeation, while at greater than 30 mol % of cholesterol the difference became minor. This tendency for the PSM and DPPC bilayers to resemble each other at higher cholesterol concentrations was similar to commonly observed trends in several structural properties, such as order parameters, cross-sectional area per molecule, and cavity density profiles in the hydrophobic regions of bilayer membranes. These results demonstrate that DPPC and PSM bilayers with high cholesterol contents possess similar physical properties, which suggests that the solubility of cholesterol in these lipid bilayers has importance for an understanding of multicomponent lipid membranes with cholesterol. PMID:22081997

Experimentally-determined structural models of fluid lipid bilayers are essential for verifying molecular dynamics simulations of bilayers and for understanding the structural consequences of peptide interactions. The extreme thermal motion of bilayers precludes the possibility of atomic-level structural models. Defining {open_quote}the structure{close_quote} of a bilayer as the time-averaged transbilayer distribution of the water and the principal lipid structural groups such as the carbonyls and double-bonds (quasimolecular fragments), one can represent the bilayer structure as a sum of Gaussian functions referred to collectively as the quasimolecular structure. One method of determining the structure is by neutron diffraction combined with exhaustive specific deuteration. This method is impractical because of the expense of the chemical syntheses and the limited amount of neutron beam time currently available. We have therefore developed the composition space refinement method for combining X-ray and minimal neutron diffraction data to arrive at remarkably detailed and accurate structures of fluid bilayers. The composition space representation of the bilayer describes the probability of occupancy per unit length across the width of the bilayer of each quasimolecular component and permits the joint refinement of X-ray and neutron lamellar diffraction data by means of a single quasimolecular structure that is fitted simultaneously to both data sets. Scaling of each component by the appropriate neutron or X-ray scattering length maps the composition-space profile to the appropriate scattering length space for comparison to experimental data. The difficulty with the method is that fluid bilayer structures are generally only marginally determined by the experimental data. This means that the space of possible solutions must be extensively explored in conjunction with a thorough analysis of errors.

Molecular dynamics simulations have been used to study the driving force of ion beam mixing in metal bilayers. We are able to explain the ion induced phase stability and melting behavior of bilayers using only a simple ballistic picture up to 10 keV ion energies. The relative masses (mass ratio) of the overlayer and the substrate constiuents seems to be a key quantity in understanding atomic mixing. The bilayer mass ratio of \\delta 0.5 ps at low-energy ion irradiation (1 keV) due to a purely ballistic mechanism.

A paint-freeze method for preparing self-assembled alkanethiol/phospholipid bilayers on a gold surface has been described (by cyclic voltammetry, a.c impedance, polarized FTIR-ATR) to be well-ordered and packed, stable, solvent-free bilayers. The lipid order parameter was 0.67, calculated from the dichroic ratio, consistent with a well-ordered lipid film in which the methylene groups have segmental flexibility and are disordered to a degree which is typical for a lipid bilayer in the liquid-crystalline phase. Such a supported membrane provides a useful way for studies in biophysics, physiology and electrochemistry.