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Sample records for compare metal ion

  1. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

    2014-07-01

    The implantation of 1 MeV metal (63Cu+, 107Ag+, 197Au+) and non-metal (4He+, 12C+) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 1013 ions cm-2, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated Cdbnd C bonds. For fluences around 1 × 1017 ions cm-2, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼107 Ω/sq has been measured for implantation with metals at doses higher than 5 × 1016 ions cm-2, being 1017 Ω/sq the corresponding sheet resistance for pristine PC.

  2. A novel Schiff base: Synthesis, structural characterisation and comparative sensor studies for metal ion detections.

    PubMed

    Köse, Muhammet; Purtas, Savas; Güngör, Seyit Ali; Ceyhan, Gökhan; Akgün, Eyup; McKee, Vickie

    2015-02-01

    A novel Schiff base ligand was synthesized by the condensation reaction of 2,6-diformylpyridine and 4-aminoantipyrine in MeOH and characterised by its melting point, elemental analysis, FT-IR, (1)H, (13)C NMR and mass spectroscopic studies. Molecular structure of the ligand was determined by single crystal X-ray diffraction technique. The electrochemical properties of the Schiff base ligand were studied in different solvents at various scan rates. Sensor ability of the Schiff base ligand was investigated by colorimetric and fluorometric methods. Visual colour change of the ligand was investigated in MeOH solvent in presence of various metal ions Na(+), Mg(2+), Al(3+), K(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+). Upon addition of Al(3+) ion into a MeOH solution of the ligand, an orange colour developed which is detectable by naked eye. Fluorescence emission studies showed that the ligand showed single emission band at 630-665nm upon excitation at 560nm. Addition of metal ions Na(+), Mg(2+), K(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+) (1:1M ratio) cause fluorescence quenching, however addition of Al(+3) resulted in an increase in fluorescence intensity. No significant variation was observed in the fluorescence intensity caused by Al(3+) in presence of other metal ions. Therefore, the Schiff base ligand can be used for selective detection of Al(3+) ions in the presence of the other metal ions studied. PMID:25459697

  3. Comparative Enzymology in the Alkaline Phosphatase Superfamily to Determine the Catalytic Role of an Active Site Metal Ion

    PubMed Central

    Zalatan, Jesse G.; Fenn, Timothy D.; Herschlag, Daniel

    2009-01-01

    Mechanistic models for biochemical systems are frequently proposed from structural data. Site-directed mutagenesis can be used to test the importance of proposed functional sites, but these data do not necessarily indicate how these sites contribute to function. Herein we apply an alternative approach to the catalytic mechanism of alkaline phosphatase (AP), a widely-studied, prototypical bimetallo enzyme. A third metal ion site in AP has been suggested to provide general base catalysis, but comparison with an evolutionarily-related enzyme casts doubt on this model. Removal of this metal site from AP has large differential effects on reactions of cognate and promiscuous substrates, and the results are inconsistent with general base catalysis. Instead, these and additional results suggest that the third metal ion stabilizes the transferred phosphoryl group in the transition state. These results establish a new mechanistic model for this prototypical bimetallo enzyme and demonstrate the power of a comparative approach for probing biochemical function. PMID:18851975

  4. Comparative effectiveness of metal ions in inducing curvature of primary roots of Zea mays

    NASA Technical Reports Server (NTRS)

    Hasenstein, K. H.; Evans, M. L.; Stinemetz, C. L.; Moore, R.; Fondren, W. M.; Koon, E. C.; Higby, M. A.; Smucker, A. J.

    1988-01-01

    We used five cultivars of Zea mays (Bear Hybrid WF9 * 38MS, B73 * Missouri 17, Yellow Dent, Merit, and Great Lakes Hybrid 422) to reinvestigate the specificity of metal ions for inducing root curvature. Of 17 cations tested, 6 (Al3+, Ba2+, Ca2+, Cd2+, Cu2+, Zn2+) induced curvature. Roots curved away from Al3+, Ba2+, and Cd2+. Roots curved away from low (0.1 millimolar) concentrations of Cu2+ but toward higher (1-5 millimolar) concentrations. Roots initially curved away from Zn2+ but the direction of the subsequent curvature was unpredictable. In most cases, roots of all cultivars curved towards calcium. However, in some tests there was no response to calcium or even (especially in the cultivars Merit and B73 * Missouri 17) substantial curvature away from calcium. The results indicate that the induction of root curvature is not specific for calcium. The results are discussed relative to the possible role of calmodulin as a mediator of ion-induced root curvature.

  5. Metal Ion Sources for Ion Beam Implantation

    SciTech Connect

    Zhao, W. J.; Zhao, Z. Q.; Ren, X. T.

    2008-11-03

    In this paper a theme touched upon the progress of metal ion sources devoted to metal ion beam implantation (MIBI) will be reviewed. A special emphasis will be given to some kinds of ion sources such as ECR, MEVVA and Cluster ion sources. A novel dual hollow cathode metal ion source named DUHOCAMIS will be introduced and discussed.

  6. Metal Ions in Unusual Valency States.

    ERIC Educational Resources Information Center

    Sellers, Robin M.

    1981-01-01

    Discusses reactivity of metal ions with the primary products of water radiolysis, hyper-reduced metal ions, zero-valent metal ions, unstable divalent ions from the reduction of bivalent ions, hyper-oxidized metal ions, and metal complexes. (CS)

  7. Comparative study of abiogenesis of cysteine and other amino acids catalyzed by various metal ions.

    PubMed

    Bahadur, K; Sen, P

    1975-01-01

    The present work pertains to the study of the influence of nickel, cobalt, thorium, vanadium, molybdate, ferrous ions on the formation of cysteine which is synthesized abiogenically together with other amino acids in sterilized aqueous mixtures of ammonium thiocyanate, formaldehyde, potassium dihydrogen phosphate, calcium acetate, and biological minerals after irradiating by artificial light. The effect of these catalysts on cysteine formation was of the order: Fe++ greater than Mo++ greater than Th++++ greater than V++ greater than Co++ greater than Ni. PMID:1189468

  8. Comparative studies on the removal of heavy metals ions onto cross linked chitosan-g-acrylonitrile copolymer.

    PubMed

    Shankar, P; Gomathi, Thandapani; Vijayalakshmi, K; Sudha, P N

    2014-06-01

    The graft copolymerization of acrylonitrile onto cross linked chitosan was carried out using ceric ammonium nitrate as an initiator. The prepared cross linked chitosan-g-acrylonitrile copolymer was characterized using FT-IR and XRD studies. The adsorption behavior of chromium(VI), copper(II) and nickel(II) ions from aqueous solution onto cross linked chitosan graft acrylonitrile copolymer was investigated through batch method. The efficiency of the adsorbent was identified from the varying the contact time, adsorbent dose and pH. The results evident that the adsorption of metal ions increases with the increase of shaking time and metal ion concentration. An optimum pH was found to be 5.0 for both Cr(VI) and Cu(II), whereas the optimum pH is 5.5 for the adsorption of Ni(II) onto cross linked chitosan-g-acrylonitrile copolymer. The Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Adsorption isothermal data could be well interpreted by the Freundlich model. The kinetic experimental data properly correlated with the second-order kinetic model. From the above results it was concluded that the cross linked chitosan graft acrylonitrile copolymer was found to be the efficient adsorbent for removing the heavy metals under optimum conditions. PMID:24680901

  9. His-containing plant metallothioneins: comparative study of divalent metal-ion binding by plant MT3 and MT4 isoforms.

    PubMed

    Tomas, Mireia; Pagani, María Ayelen; Andreo, Carlos S; Capdevila, Mercè; Bofill, Roger; Atrian, Sílvia

    2014-10-01

    Metallothioneins (MTs) are a superfamily of Cys-rich, low-molecular weight metalloproteins that bind heavy metal ions. These cytosolic metallopeptides, which exist in most living organisms, are thought to be involved in metal homeostasis, metal detoxification, and oxidative stress protection. In this work, we characterise the Zn(II)- and Cd(II)-binding abilities of plant type 3 and type 4 MTs identified in soybean and sunflower, both of them being His-containing peptides. The recombinant metal-MT complexes synthesised in Zn(II) or Cd(II)-enriched Escherichia coli cultures have been analysed by ESI-MS, and CD, ICP-AES, and UV spectroscopies. His-to-Ala type 3 MT mutants have also been constructed and synthesised for the study of the role of His in divalent metal ion coordination. The results show comparable divalent metal-binding capacities for the MTs of type 3, and suggest, for the first time, the participation of their conserved C-term His residues in metal binding. Interesting features for the Zn(II)-binding abilities of type 4 MTs are also reported, as their variable His content may be considered crucial for their biological performance. PMID:24951240

  10. Photoelectrochemical detection of metal ions.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-07-21

    Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented. PMID:27297834

  11. Immobilized metal ion affinity chromatography.

    PubMed

    Yip, T T; Hutchens, T W

    1992-01-01

    Immobilized metal ion affinity chromatography (IMAC) (1,2) is also referred to as metal chelate chromatography, metal ion interaction chromatography, and ligand-exchange chromatography. We view this affinity separation technique as an intermediate between highly specific, high-affinity bioaffinity separation methods, and wider spectrum, low-specificity adsorption methods, such as ion exchange. The IMAC stationary phases are designed to chelate certain metal ions that have selectivity for specific groups (e.g., His residues) in peptides (e.g., 3-7) and on protein surfaces (8-13). The number of stationary phases that can be synthesized for efficient chelation of metal ions is unlimited, but the critical consideration is that there must be enough exposure of the metal ion to interact with the proteins, preferably in a biospecific manner. Several examples are presented in Fig. 1. The challenge to produce new immobilized chelating groups, including protein surface metal-binding domains (14,15) is being explored continuously. Table 1 presents a list of published procedures for the synthesis and use of stationary phases with immobilized chelating groups. This is by no means exhaustive, and is intended only to give an idea of the scope and versatility of IMAC. Fig. 1 Schematic illustration of several types of immobilized metal-chelating groups, including, iminodiacetate (IDA), tris(carboxymethyl) ethylenediamine (TED), and the metal-binding peptides (GHHPH)(n)G (where n = 1,2,3, and 5) (14,15). Table 1 Immobilized Chelating Groups and Metal Ions Used for Immobilized Metal Ion Affinity Chromatography Chelating group Suitable metal ions Reference Commercial source Immodiacetate Transitional1,2 Pharmacia LKB Pierce Sigma Boehringer Mannheim TosoHaas 2-Hydroxy-3[N-(2- pyrtdylmethyl) glycme]propyl Transitional3 Not available ?-Alky1 mtrilo triacetic acid Transitional4 Not available Carboxymethylated asparhc acid Ca(II)13 Not available Tris (carboxy- methyl) ethylene Diamme

  12. A comparative study of the removal of heavy metal ions from water using a silica-polyamine composite and a polystyrene chelator resin

    SciTech Connect

    Beatty, S.T.; Fischer, R.J.; Hagers, D.L.; Rosenberg, E.

    1999-11-01

    The maximum Cu(II), Ni(II), and Co(II) ion capacities of a silica-poly(ethyleneimine) composite (WP-1) are compared with those of the commercially available iminodiacetic acid chelator resin Amberlite IRC-718. Under batch (static) conditions, IRC-718 exhibits better capacities for these metals than WP-1. Dynamic studies, however, revealed that WP-1 possessed a much higher capacity for all three divalent metals than IRC-718, with relative metal capacities in the order CU(II) {gt} CO(II) {approximately} Ni(II). In the presence of the competing chelator ethylenediaminetetraacetic acid, the Cu(II) capacities of WP-1 and IRC-718 lost 48% and 45%, respectively, of their original adsorption values. Even with this decrease, however, WP-1 maintained a higher CU(II) capacity than IRC-718. Repeated cycle testing, using CU(II) solutions at both room temperature and 97 C, was conducted to compare the long-term stability of each material. WP-1 maintained 94% of its original Cu(II) capacity and maintained structural integrity after 3,000 cycles using room temperature copper solutions, while IRC-718 compressed and dropped to 64% of its original capacity. When boiling copper solutions were used, the capacity of WP-1 increased slightly over 1500 cycles, while IRC-718 lost 13% of its original copper capacity and again became compressed, indicating degradation of the polystyrene beads.

  13. Comparative studies on adsorptive removal of heavy metal ions by biosorbent, bio-char and activated carbon obtained from low cost agro-residue.

    PubMed

    Kırbıyık, Çisem; Pütün, Ayşe Eren; Pütün, Ersan

    2016-01-01

    In this study, Fe(III) and Cr(III) metal ion adsorption processes were carried out with three adsorbents in batch experiments and their adsorption performance was compared. These adsorbents were sesame stalk without pretreatment, bio-char derived from thermal decomposition of biomass, and activated carbon which was obtained from chemical activation of biomass. Scanning electron microscopy and Fourier transform-infrared techniques were used for characterization of adsorbents. The optimum conditions for the adsorption process were obtained by observing the influences of solution pH, adsorbent dosage, initial solution concentration, contact time and temperature. The optimum adsorption efficiencies were determined at pH 2.8 and pH 4.0 for Fe(III) and Cr(III) metal ion solutions, respectively. The experimental data were modelled by different isotherm models and the equilibriums were well described by the Langmuir adsorption isotherm model. The pseudo-first-order, pseudo-second-order kinetic, intra-particle diffusion and Elovich models were applied to analyze the kinetic data and to evaluate rate constants. The pseudo-second-order kinetic model gave a better fit than the others. The thermodynamic parameters, such as Gibbs free energy change ΔG°, standard enthalpy change ΔH° and standard entropy change ΔS° were evaluated. The thermodynamic study showed the adsorption was a spontaneous endothermic process. PMID:26819399

  14. Comparative assessment of the effects of salinomycin and monensin on the biodistribution of lead and some essential metal ions in mice, subjected to subacute lead intoxication.

    PubMed

    Ivanova, Juliana; Gluhcheva, Yordanka; Dimova, Donika; Pavlova, Ekaterina; Arpadjan, Sonja

    2016-01-01

    In this study, we present a comparative assessment of the effects of two polyether ionophorous antibiotics (monensin and salinomycin) on the concentrations of lead (Pb), cooper (Cu), zinc (Zn) and iron (Fe) in the kidneys, spleen, liver and brain of Pb-intoxicated animals. Our data demonstrated that the intoxication of ICR male mice with Pb salt resulted in a significant accumulation of Pb in all studied organs of the mice compared to the untreated control animals. The biodistribution of the toxic metal was in the order kidneys>spleen>liver>brain. The treatment of the Pb-intoxicated animals with tetraethylammonium salts of monensic and salinomycinic acids significantly decreased the concentration of the toxic metal ion compared to the toxic control. The effect varied in the interval 38% (for kidneys) to 52% (for brain) compared to the toxic control group (Pb). The tetraethylammonium salt of salinomycinic acid was more effective in reducing the Pb concentration in the brain of the Pb-treated mice compared to monensin. Pb-intoxication did not affect significantly the Zn endogenous concentration compared to the normal values. The treatment of ICR male mice with Pb-salt decreased the Cu concentration in the spleen and increased the Cu concentration in the liver compared to the untreated control animals. The detoxification of the Pb-intoxicated mice with tetraethylammonium salts of salinomycinic and monensic acids restored the Cu concentration in the spleen, but did not affect the Cu levels in the liver. The Pb-intoxication of the ICR mice resulted in a significant decrease of the Fe-concentration in the spleen and liver compared to the untreated control animals. The administration of the tetraethylammonium salts of salinomycinic and monensic acids to the Pb-treated animals restored the levels of Fe in both organs. PMID:26653741

  15. Ion beam modification of metals

    NASA Astrophysics Data System (ADS)

    Dearnaley, G.

    1990-04-01

    Energetic ions beams may be used in various ways to modify and so improve the tribological properties of metals. These methods include: — ion implantation of selected additive species; — ion beam mixing of thin deposited coatings; — ion-beam-assisted deposition of thicker overlay coatings. The first of these techniques has been widely used to modify the electronic properties of semiconductors, but has since been extended for the treatment of all classes of material. Tool steels can be strengthened by the ion implantation of nitrogen or titanium, to produce fine dispersions of hard second-phase precipitates. Solid solution strengthening, by combinations of substitutional and interstitial species, such as yttrium and nitrogen, has also been successful. Both ion beam mixing (IBM) and ion-beam-assisted deposition (IBAD) use a combination of coating and ion bombardment. In the first case, the objective is to intermix the coating and substrate by the aid of radiation-enhanced diffusion. In the latter case, the coating is densified and modified during deposition and the process can be continued in order to build up overlay coatings several μm in thickness. The surface can then be tailored, for instance to provide a hard and adherent ceramic such as silicon nitride, boron nitride or titanium nitride. It is an advantage that all the above processes can be applied at relatively low temperatures, below about 200° C, thereby avoiding distortion of precision components. Ion implantation is also being successfully applied for the reduction of corrosion, especially at high temperatures or in the atmosphere and to explore the mechanisms of oxidation. Ion-assisted coatings, being compact and adherent, provide a more substantial protection against corrosion: silicon nitride and boron nitride are potentially useful in this respect. Examples will be given of the successful application of these methods for the surface modification of metals and alloys, and developments in the

  16. An ab initio molecular orbital study comparing the bonding of the NH3 and the H2O in the monoammines and the monohydrates of main group and transition metal ions

    NASA Astrophysics Data System (ADS)

    George, Philip; Glusker, Jenny P.; Markham, George D.; Trachtman, Mendel; Bock, Charles W.

    It is common knowledge that some metal ions prefer to bond to nitrogen atoms, others prefer oxygen and others select sulfur, although the mechanistic origin of this behaviour is not well understood. To provide quantitative data that can illuminate this characteristic difference, we have been performing ab initio molecular orbital calculations on complexes of a wide variety of main group and transition metal ions with simple ligands. In this paper we concentrate on metal ion complexes of NH3 and compare them with the corresponding complexes with H2O (Trachtman et al., 1998, Inorg. Chem., 37, 4221). The results reported here show that for each metal ion the bonding to ammonia in monoammines is intrinsically stronger than that to water in monohydrates, but that the enthalpy of formation of the amine complexes has a greater sensitivity to the nature of the metal ion. For both mono- and divalent transition metal cations the ligand-field stabilization energy (LFSE) in the monoammine complexes is larger than that in the monohydrates, although the larger enthalpies of formation, , for the monoammines are due only in part to the larger LFSE values. The formation of both monoammines and monohydrates is accompanied by a transfer of charge from the ligand hydrogen atoms to the metal ion so that there is relatively little change in the net charge on the oxygen or nitrogen atoms. Hence the increased acidity of the ligand in the metal ion complex is not the result of net electron depletion of the atom that is directly bonded to the metal ion, but rather reflects weakening of the bond of that ligand atom to its proton (O-H or N-H). This characteristic is used by many enzymes to promote catalytic activity.

  17. Metal ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1982-01-01

    A variety of metallic and organometallic complexes to be used as potential additives for an epoxy used by the aerospace industry as a composite matrix resin were investigated. A total of 9 complexes were screened for compatibility and for their ability to accelerate or inhibit the cure of a highly crosslinkable epoxy resin. Methods for combining the metallic complexes with the resin were investigated, gel times recorded, and cure exotherms studied by differential scanning calorimetry. Glass transition temperatures of cured metal ion containing epoxy castings were determined by thermomechanical analysis. Thermal stabilities of the castings were determined by thermogravimetric analysis. Mechanical strength and stiffness of these doped epoxies were also measured.

  18. Metal ion complexation properties of fulvic acids extracted from composted sewage sludge as compared to a soil fulvic acid.

    PubMed

    Esteves da Silva, Joaquim C G; Oliveira, César J S

    2002-07-01

    Complexation properties of an anthropogenic fulvic acid (FA) extracted from a composted sewage sludge (csFA) for Cu(II), Pb(II) and Cd(II) were studied at pH=6 and at a concentration of 25 mg L(-1). For the case of Cu(II), a particular analysis of the complexation phenomena was done at pH values of 3, 4, 5 and 6 and at aqueous FA concentrations of 25, 50 and 100 mg L(-1) by synchronous excitation molecular fluorescence spectroscopy (SyF). Potentiometric titrimetry with Cu(II), Pb(II), Cd(II) and H+ ion-selective electrodes and acid-base conductimetric titrations were used to obtain experimental information about the acid properties and complexation phenomena. A comparison of the results obtained for csFA with a natural soil FA (sFA) was made. Differences have been detected in the structural composition of the two samples and in the structure of the binding sites. In the csFA, binding site structures containing nitrogen probably play an important role in the complexation, besides oxygen containing structures. Complexation by sFA is mainly due to carboxylic and phenolic structures. Nevertheless, this work shows that csFA have macroscopic complexation properties (magnitude of the conditional stability constant and binding sites concentration) somewhat similar to the natural sFA samples. PMID:12188141

  19. Electrochemical Stability of Carbon Fibers Compared to Metal Foils as Current Collectors for Lithium-Ion Batteries

    SciTech Connect

    Martha, Surendra K; Dudney, Nancy J; Kiggans, Jim; Nanda, Jagjit

    2012-01-01

    The electrochemical behaviors of highly conductive, fully-graphitic, semi-graphitic and non-graphitic carbon fibers were studied as the cathode current collectors of lithium batteries in standard electrolyte (alkyl carbonate/LiPF6) solutions and compared to bare aluminum (Al). All of these current collectors demonstrate a stable electrochemical behavior within the potential range of 2.5 to 5 V, due to passivation by surface films. Carbon fibers have comparable electrochemical stability of Al and may be used in place Al foil. While the carbon fibers do not contribute any irreversible or extra capacity when they are cycled below 4.5 V, for fully-graphitic and semi-graphitic fibers PF6 intercalation and deintercalation into the carbon fiber may occur when they are cycled at high potentials >4.5 V.

  20. Mechanistic Enzyme Models: Pyridoxal and Metal Ions.

    ERIC Educational Resources Information Center

    Hamilton, S. E.; And Others

    1984-01-01

    Background information, procedures, and results are presented for experiments on the pyridoxal/metal ion model system. These experiments illustrate catalysis through Schiff's base formation between aldehydes/ketones and primary amines, catalysis by metal ions, and the predictable manner in which metal ions inhibit or catalyze reactions. (JN)

  1. Reversible photodeposition and dissolution of metal ions

    DOEpatents

    Foster, Nancy S.; Koval, Carl A.; Noble, Richard D.

    1994-01-01

    A cyclic photocatalytic process for treating waste water containing metal and organic contaminants. In one embodiment of the method, metal ions are photoreduced onto the photocatalyst and the metal concentrated by resolubilization in a smaller volume. In another embodiment of the method, contaminant organics are first oxidized, then metal ions removed by photoreductive deposition. The present invention allows the photocatalyst to be recycled until nearly complete removal of metal ions and organic contaminants is achieved.

  2. Metallic ions in the equatorial ionosphere

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.; Goldberg, R. A.

    1972-01-01

    Four positive ion composition measurements of the equatorial E region made at Thumba, India, are presented. During the day, the major ions between 90 and 125 km are NO(+) and O2(+). A metallic ion layer centered at 92 km is observed, and found to contain Mg(+), Fe(+), Ca(+), K(+), Al(+), and Na(+) ions. The layer is explained in terms of a similarly shaped latitude distribution of neutral atoms which are photoionized and charge-exchanged with NO(+) and O2(+). Three body reactions form molecular metallic ions which are rapidly lost by dissociative ion-electron recombination. Nighttime observations show downward drifting of the metallic ion layer caused by equatorial dynamo effects. These ions react and form neutral metals which exchange charges with NO(+) and O2(+) to produce an observed depletion of those ions within the metallic ion region.

  3. Biopharmaceutical characterisation of ciprofloxacin-metallic ion interactions: comparative study into the effect of aluminium, calcium, zinc and iron on drug solubility and dissolution.

    PubMed

    Stojković, Aleksandra; Tajber, Lidia; Paluch, Krzysztof J; Djurić, Zorica; Parojčić, Jelena; Corrigan, Owen I

    2014-03-01

    Ciprofloxacin bioavailability may be reduced when ciprofloxacin is co-administered with metallic ion containing preparations. In our previous study, physicochemical interaction between ciprofloxacin and ferrous sulphate was successfully simulated in vitro. In the present work, comparative in vitro ciprofloxacin solubility and dissolution studies were performed in the reactive media containing aluminium hydroxide, calcium carbonate or zinc sulphate. Solid phases collected from the dissolution vessel with aluminium hydroxide, calcium carbonate and zinc sulphate were investigated for their properties. The results obtained indicate that different types of adducts may form and retard ciprofloxacin solubility and dissolution. In the case of aluminium, no phase changes were observed. The solid phase generated in the presence of calcium carbonate was identified as hydrated ciprofloxacin base. Similarly to iron, a new complex consistent with Zn(SO4)2(Cl)2(ciprofloxacin)2 × nH2O stoichiometry was generated in the presence of relatively high concentrations of ciprofloxacin hydrochloride and zinc sulphate, indicating that small volume dissolution experiments can be useful for biorelevant dissolution tests. PMID:24670353

  4. A biosystem for removal of metal ions from water

    SciTech Connect

    Kilbane, J.J. II.

    1990-01-01

    The presence of heavy metal ions in ground and surface waters constitutes a potential health risk and is an environmental concern. Moreover, processes for the recovery of valuable metal ions are of interest. Bioaccumulation or biosorption is not only a factor in assessing the environmental risk posed by metal ions; it can also be used as a means of decontamination. A biological system for the removal and recovery of metal ions from contaminated water is reported here. Exopolysaccharide-producing microorganisms, including a methanotrophic culture, are demonstrated to have superior metal binding ability, compared with other microbial cultures. This paper describes a biosorption process in which dried biomass obtained from exopolysaccharide-producing microorganisms is encapsulated in porous plastic beads and is used for metal ion binding and recovery. 22 refs., 13 figs.

  5. Protein-Transition Metal Ion Networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins obtained from agricultural sources were blended with divalent metal ions. Feather keratin, egg albumin, and wheat gluten showed increases of 2-3 times in modulus with addition of divalent transition metal ions Cu2+ and Zn2+. Increasing concentrations of ions resulted in increased stiffnes...

  6. Metal ions, Alzheimer's disease and chelation therapy.

    PubMed

    Budimir, Ana

    2011-03-01

    In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases. PMID:21406339

  7. Ion irradiation effects on metallic nanocrystals

    NASA Astrophysics Data System (ADS)

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C. S.; Foran, G. J.; Cookson, D. J.; Byrne, A. P.; Ridgway, M. C.

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO2. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO2 interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  8. Ohmic model for electrodeposition of metallic ions

    NASA Astrophysics Data System (ADS)

    Gliozzi, A. S.; Alexe-Ionescu, A. L.; Barbero, G.

    2015-10-01

    An ohmic model to describe the electrodeposition of metallic ions on the electrodes is proposed. We assume that the ionic distribution is homogeneous across the electrolytic cell, and that the ionic current is due to the bulk electric field. The nucleation in the electrodeposition is supposed to be well described by a kinetic equation at the electrode, taking into account the neutralization of metallic ions on the electrodes. Two cases are considered. In the first case the characteristic time describing the neutralization of the ions is supposed to be negligible with respect to the flight time of the ions across the cell. In this framework the bulk electric field coincides with the external electric field, and our analysis gives analytical formulae for the surface density of deposited ions and for the electric current in the external circuit. The case where the two characteristic times are comparable, and the effective electric field in the bulk depends on the surface deposition, is considered too. In this case the ordinary differential equations describing the ionic distribution and the adsorption phenomenon have to be solved numerically. The agreement between the presented model and the experimental results published by several groups is reasonably good.

  9. Ion irradiation effects on metallic nanocrystals

    SciTech Connect

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C.S.; Foran, G.J.; Cookson, D.J.; Byrne, A.P.; Ridgway, M.C.

    2008-04-02

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO{sub 2}. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO{sub 2} interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  10. Liquid metal ion source and alloy

    DOEpatents

    Clark, Jr., William M.; Utlaut, Mark W.; Behrens, Robert G.; Szklarz, Eugene G.; Storms, Edmund K.; Santandrea, Robert P.; Swanson, Lynwood W.

    1988-10-04

    A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

  11. Multiply stripped ion generation in the metal vapor vacuum arc

    SciTech Connect

    Brown, I.G.; Feinberg, B.; Galvin, J.E.

    1986-08-01

    We consider the charge state distribution of ions produced in the metal vapor vacuum arc plasma discharge. A high current metal ion source, the MEVVA ion source, in which the ion beam is extracted from a metal vapor vacuum arc plasma, has been used to obtain the spectra of multiple charged ions produced within the cathode spots. A computer calculation of the charge state distribution that evolves within the spots via stepwide ionization of ions by electron impact provides a theoretical basis for comparison of the data. In this paper we report on the measured charge state distributions for a wide variety of metallic species and compare these results with the predictions of this theory. 55 refs.

  12. Versatile high current metal ion implantation facility

    SciTech Connect

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1991-06-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multi-cathode, broad beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion-charge state multiplicity, and with a beam current of up to several amperes peak pulsed and several tens of mA time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. 28 refs., 5 figs.

  13. Comparative SEU sensitivities to relativistic heavy ions

    SciTech Connect

    Koga, R.; Crain, S.H.; Crain, W.R.; Crawford, K.B.; Hansel, S.J.

    1998-12-01

    SEU sensitivity of microcircuits to relativistic heavy ions is compared to that measured with low-energy ions of comparable LET values. Multiple junction charge collection in a complex circuit seems to mask the effect of varying charge generations due to different iron track structures. Heavy ions at sub-relativistic speeds may generate nuclear fragments, sometimes resulting in SEUs.

  14. COMPUTATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS

    EPA Science Inventory

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides...

  15. Pseudo ribbon metal ion beam source

    SciTech Connect

    Stepanov, Igor B. Ryabchikov, Alexander I.; Sivin, Denis O.; Verigin, Dan A.

    2014-02-15

    The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface.

  16. Separation of metal ions from aqueous solutions

    DOEpatents

    Almon, Amy C.

    1994-01-01

    A process and apparatus for quantitatively and selectively separating metal ions from mixtures thereof in aqueous solution. The apparatus includes, in combination, a horizontal electrochemical flow cell containing flow bulk electrolyte solution and an aqueous, metal ion-containing solution, the cell containing a metal mesh working electrode, a counter electrode positioned downstream from the working electrode, an independent variable power supply/potentiostat positioned outside of the flow cell and connected to the electrodes, and optionally a detector such as a chromatographic detector, positioned outside the flow cell. This apparatus and its operation has significant application where trace amounts of metal ions are to be separated.

  17. Metal ion adsorption at the ionic liquid-mica interface

    NASA Astrophysics Data System (ADS)

    McDonald, Samila; Elbourne, Aaron; Warr, Gregory G.; Atkin, Rob

    2015-12-01

    Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ~60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al3+ system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made.Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete

  18. Metal ion adsorption to complexes of humic acid and metal oxides: Deviations from the additivity rule

    SciTech Connect

    Vermeer, A.W.P.; McCulloch, J.K.; Van Riemsdijk, W.H.; Koopal, L.K.

    1999-11-01

    The adsorption of cadmium ions to a mixture of Aldrich humic acid and hematite is investigated. The actual adsorption to the humic acid-hematite complex is compared with the sum of the cadmium ion adsorptivities to each of the isolated components. It is shown that the sum of the cadmium ion adsorptivities is not equal to the adsorption to the complex. In general, the adsorption of a specific metal ion to the complex can be understood and qualitatively predicted using the adsorptivities to each of the pure components and taking into account the effect of the pH on the interaction between humic acid and iron oxide on the metal ion adsorption. Due to the interaction between the negatively charged humic acid and the positively charged iron oxide, the adsorption of metal ions on the mineral oxide in the complex will increase as compared to that on the isolated oxide, whereas the adsorption to the humic acid will decrease as compared to that on the isolated humic acid. As a result, the overall adsorption of a specific metal ion to the complex will be smaller than predicted by the additivity rule when this metal ion has a more pronounced affinity for the humic acid than for the mineral oxide, whereas it will be larger than predicted by the additivity rule when the metal ion has a higher affinity for the oxide than for the humic acid.

  19. Metallic ion production with the dione EBIS

    NASA Astrophysics Data System (ADS)

    Visentin, B.; Courtois, A.; Gobin, R.; Harrault, F.; Leroy, P. A.

    1997-01-01

    We report the first quantitative results obtained with metallic elements injected from an Hollow Cathode ion source into the Dioné EBIS. These results are concerned with the charge state distribution of gold ions, with a maximum for Au47+ of (1,3 × 107 ions), and the highest charge state detectable on a wire profiler of Au63+. The Au50+ ions have been captured in Mimas storage synchrotron, and an Fe20+ ion beam has been accelerated in the Saturne synchrotron. The Hollow Cathode ion source lifetime has been tested on a long term basis (Au1+ injected into Dioné during six weeks, 24 hours per day). This source, able to produce metallic ions with any buffer gas (Ne, Ar, Kr, Xe, or N) and is also used to inject gaseous ions into Dioné.

  20. Metal ion adsorption at the ionic liquid-mica interface.

    PubMed

    McDonald, Samila; Elbourne, Aaron; Warr, Gregory G; Atkin, Rob

    2016-01-14

    Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ∼60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al(3+) system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made. PMID:26661934

  1. Effects of metal ions on fibroblasts and spiral ganglion cells.

    PubMed

    Paasche, G; Ceschi, P; Löbler, M; Rösl, C; Gomes, P; Hahn, A; Rohm, H W; Sternberg, K; Lenarz, T; Schmitz, K-P; Barcikowski, S; Stöver, T

    2011-04-01

    Degeneration of spiral ganglion cells (SGC) after deafness and fibrous tissue growth around the electrode carrier after cochlear implantation are two of the major challenges in current cochlear implant research. Metal ions are known to possess antimicrobial and antiproliferative potential. The use of metal ions could therefore provide a way to reduce tissue growth around the electrode array after cochlear implantation. Here, we report on in vitro experiments with different concentrations of metal salts with antiproliferative and toxic effects on fibroblasts, PC-12 cells, and freshly isolated spiral ganglion cells, the target cells for electrical stimulation by a cochlear implant. Standard cell lines (NIH/3T3 and L-929 fibroblasts and PC-12 cells) and freshly isolated SGC were incubated with concentrations of metal ions between 0.3 μmol/liter and 10 mmol/liter for 48 hr. Cell survival was investigated by neutral red uptake, CellQuantiBlue assay, or counting of stained surviving neurons. Silver ions exhibited distinct thresholds for proliferating and confluent cells. For zinc ions, the effective concentration was lower for fibroblasts than for PC-12 cells. SGC showed comparable thresholds for reduced cell survival not only for silver and zinc ions but also for copper(II) ions, indicating that these ions might be promising for reducing tissue growth on the surface of CI electrode arrays. These effects were also observed when combinations of two of these ions were investigated. PMID:21312225

  2. Fluorescence enhancement aided by metal ion displacement.

    PubMed

    Susini, Vanessa; Ienco, Andrea; Lucia Rossi, Veronica; Paolicchi, Aldo; Sanesi, Antonio

    2016-06-15

    Immunosensors are one of the most common platform used in clinical laboratories, in particular the class based on Enzyme Linked Fluorescent Assays (ELFA) takes advantage of the amplification step of the enzyme, usually the alkaline phosphatase, that catalyzes the hydrolysis of a fluorescent substrate leading it to fluoresce. Anyway, they suffer in sensitivity if compared to molecular diagnostic or more modern in vitro diagnostic devices. In our work, a simple and effective mechanism to enhance the fluorescent signal, and hence the sensitivity of the system, is presented. It is based on the metal ion displacement principle in which a second fluorophore, in our case Calcein Blue, quenched by a cobalt ion is add to the first one (4-MUP), and, in presence of inorganic phosphate, it will be progressively activated by the inorganic phosphate itself leading to the metal displacement. In this way Calcein Blue, newly free to fluoresce, contributes to global fluorescent signal generated by 4-MU. We have tested our proof of principle on a currently used immunoanalyzer, that is VIDAS® system (bioMérieux, Marcy l'Etoile, France) obtaining a fluorescence enhancement of about 50% for each concentration of hydrolyzed 4-MUP tested. PMID:26851581

  3. Uptake of metal ions on humic acids

    SciTech Connect

    Pehlivan, E.; Arslan, G.

    2006-09-15

    The kinetics, the sorption capacities, pH and temperature dependence of sorption of humic acids (HAs) of Turkish brown coals with respect to Zn(II), Cu(II), Ni(II), Co(II) and Pb(II) ions were investigated, and the roles of the carboxylic and phenolic groups in the adsorption of metals ion on HAs were searched in this work. These metal ions are able to form complex compounds with carboxylic and phenolic groups of HAs. Adsorption equilibrium was achieved in between 50 and 60 min for all studied cations. HAs extracted from different brown coals have been characterized by chemical and physical methods. The chemical properties of HAs showed differences depending on the source from which they were obtained. The sorption of metals on the surface of HAs depends strongly on the pH, and sorption decreases with decreasing pH. Maximum removal of metal ions was demonstrated at pH values of 4.1-5.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The {Delta}G{sup 0} became negative as the temperature increased, and so the equilibrium constant decreased slightly. The investigation proved that the HAs are suitable materials for the studied heavy metal ion removal from aqueous solution and could be considered as potential material for purification of effluent polluted with toxic metal ions.

  4. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

    A corrosion control pipe loop study to evaluate the effect of ion exchange water softening on metal leaching from household plumbing materials was conducted on two different water qualities having different pH's and hardness levels. The results showed that removing hardness ions ...

  5. Comparing electrochemical performance of transition metal silicate cathodes and chevrel phase Mo6S8 in the analogous rechargeable Mg-ion battery system

    NASA Astrophysics Data System (ADS)

    Chen, Xinzhi; Bleken, Francesca L.; Løvvik, Ole Martin; Vullum-Bruer, Fride

    2016-07-01

    Polyanion based silicate materials, MgMSiO4 (M = Fe, Mn, Co), previously reported to be promising cathode materials for Mg-ion batteries, have been re-examined. Both the sol-gel and molten salt methods are employed to synthesize MgMSiO4 composites. Mo6S8 is synthesized by a molten salt method combined with Cu leaching and investigated in the equivalent electrochemical system as a bench mark. Electrochemical measurements for Mo6S8 performed using the 2nd generation electrolyte show similar results to those reported in literature. Electrochemical performance of the silicate materials on the other hand, do not show the promising results previously reported. A thorough study of these published results are presented here, and compared to the current experimental data on the same material system. It appears that there are certain inconsistencies in the published results which cannot be explained. To further corroborate the present experimental results, atomic-scale calculations from first principles are performed, demonstrating that diffusion barriers are very high for Mg diffusion in MgMSiO4. In conclusion, MgMSiO4 (M = Fe, Mn, Co) olivine materials do not seem to be such good candidates for cathode materials in Mg-ion batteries as previously reported.

  6. Metal-ion recycle technology for metal electroplating waste waters

    SciTech Connect

    Sauer, N.N.; Smith, B.F.

    1993-06-01

    As a result of a collaboration with Boeing Aerospace, the authors have begun a program to identify suitable treatments or to develop new treatments for electroplating baths. The target baths are mixed-metal or alloy baths that are being integrated into the Boeing electroplating complex. These baths, which are designed to replace highly toxic chromium and cadmium baths, contain mixtures of two metals, either nickel-tungsten, nickel-zinc, or zinc-tin. This report reviews the literature and details currently available on emerging technologies that could affect recovery of metals from electroplating baths under development by Boeing Aerospace. This literature survey summarizes technologies relevant to the recovery of metals from electroplating processes. The authors expanded the scope to investigate single metal ion recovery technologies that could be applied to metal ion recovery from alloy baths. This review clearly showed that the electroplating industry has traditionally relied on precipitation and more recently on electrowinning as its waste treatment methods. Despite the almost ubiquitous use of precipitation to remove contaminant metal ions from waste electroplating baths and rinse waters, this technology is clearly no longer feasible for the electroplating industry for several reasons. First, disposal of unstabilized sludge is no longer allowed by law. Second, these methods are no longer adequate as metal-removal techniques because they cannot meet stringent new metal discharge limits. Third, precious resources are being wasted or discarded because these methods do not readily permit recovery of the target metal ions. As a result, emerging technologies for metal recovery are beginning to see application to electroplating waste recycle. This report summarizes current research in these areas. Included are descriptions of various membrane technologies, such as reverse osmosis and ultrafiltration, ion exchange and chelating polymer technology, and electrodialysis.

  7. Upgraded vacuum arc ion source for metal ion implantation

    SciTech Connect

    Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.; Brown, I. G.

    2012-02-15

    Vacuum arc ion sources have been made and used by a large number of research groups around the world over the past twenty years. The first generation of vacuum arc ion sources (dubbed ''Mevva,'' for metal vapor vacuum arc) was developed at Lawrence Berkeley National Laboratory in the 1980s. This paper considers the design, performance parameters, and some applications of a new modified version of this kind of source which we have called Mevva-V.Ru. The source produces broad beams of metal ions at an extraction voltage of up to 60 kV and a time-averaged ion beam current in the milliampere range. Here, we describe the Mevva-V.Ru vacuum arc ion source that we have developed at Tomsk and summarize its beam characteristics along with some of the applications to which we have put it. We also describe the source performance using compound cathodes.

  8. Bioavailability of Metal Ions and Evolutionary Adaptation

    PubMed Central

    Hong Enriquez, Rolando P.; Do, Trang N.

    2012-01-01

    The evolution of life on earth has been a long process that began nearly 3.5 × 109 years ago. In their initial moments, evolution was mainly influenced by anaerobic environments; with the rise of O2 and the corresponding change in bioavailability of metal ions, new mechanisms of survival were created. Here we review the relationships between ancient atmospheric conditions, metal ion bioavailability and adaptation of metals homeostasis during early evolution. A general picture linking geochemistry, biochemistry and homeostasis is supported by the reviewed literature and is further illustrated in this report using simple database searches. PMID:25371266

  9. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2006-06-01

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort.

  10. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2005-06-15

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort.

  11. A vacuum spark ion source: High charge state metal ion beams

    NASA Astrophysics Data System (ADS)

    Yushkov, G. Yu.; Nikolaev, A. G.; Oks, E. M.; Frolova, V. P.

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  12. A vacuum spark ion source: High charge state metal ion beams.

    PubMed

    Yushkov, G Yu; Nikolaev, A G; Oks, E M; Frolova, V P

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described. PMID:26931966

  13. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2005-06-15

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort. This project seeks to enhance and strengthen the traditional approach through computer-aided design of new and improved host molecules. Accurate electronic structure calculations are coupled with experimental data to provide fundamental information about ligand structure and the nature of metal-donor group interactions (design criteria). This fundamental information then is used in a molecular mechanics model (MM) that helps us rapidly screen proposed ligand architectures and select the best members from a set of potential candidates. By using combinatorial methods, molecule building software has been developed that generates large numbers of candidate architectures for a given set of donor groups. The specific goals of this project are: • further understand the structural and energetic aspects of individual donor group- metal ion interactions and incorporate this information within the MM framework • further develop and evaluate approaches for correlating ligand structure with reactivity toward metal ions, in other words, screening capability • use molecule structure building software to generate

  14. Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?

    PubMed Central

    Moroni, Antonio; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

    2008-01-01

    Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18196364

  15. Effect of metal ions on positron annihilation characteristics in metal ion containing epoxies

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; St. Clair, A. K.; Stoakley, D. M.; Holt, W. H.; Mock, W., Jr.

    1984-01-01

    In the course of developing improved moisture-resistant epoxy resins, two different types of epoxy resins containing variable mole ratios of chromium ions per polymer repeat unit were developed. Positron annihilation characteristics have been investigated in these resins as a function of their metal ion content. In both cases, the presence of metal ions reduces the lifetime as well as the intensity of the long life component. The long life component intensity reduction is considerably more pronounced than the lifetime reduction. These results have been discussed in terms of increased unpaired electron density at Ps formation sites due to the presence of chromium ions in the matrix.

  16. IMMUNOASSAYS FOR METAL IONS. (R824029)

    EPA Science Inventory

    Abstract

    Antibodies that recognize chelated forms of metal ions have been used to construct immunoassays for Cd(II), Hg(II), Pb(II), and Ni(II). In this paper, the format of these immunoassays is described and the binding properties of three monoclonal antibodies direc...

  17. Material Removes Heavy Metal Ions From Water

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H., Jr.; Street, Kenneth W.; Hill, Carol; Savino, Joseph M.

    1995-01-01

    New high capacity ion-exchange polymer material removes toxic metal cations from contaminated water. Offers several advantages. High sensitivities for such heavy metals as lead, cadmium, and copper and capable of reducing concentrations in aqueous solutions to parts-per-billion range. Removes cations even when calcium present. Material made into variety of forms, such as thin films, coatings, pellets, and fibers. As result, adapted to many applications to purify contaminated water, usually hard wherever found, whether in wastewater-treatment systems, lakes, ponds, industrial plants, or homes. Another important feature that adsorbed metals easily reclaimed by either destructive or nondestructive process. Other tests show ion-exchange polymer made inexpensively; easy to use; strong, flexible, not easily torn; and chemically stable in storage, in aqueous solutions, and in acidic or basic solution.

  18. Metal plasma immersion ion implantation and deposition: A review

    SciTech Connect

    Anders, A.

    1996-09-01

    Metal Plasma Immersion Ion Implantation and Deposition (MePIIID) is a hybrid process combining cathodic arc deposition and plasma immersion ion implantation. The properties of metal plasma produced by vacuum arcs are reviewed and the consequences for MePIIID are discussed. Different version of MePIIID are described and compared with traditional methods of surface modification such as ion beam assisted deposition (IBAD). MePIIID is a very versatile approach because of the wide range of ion species and energies used. In one extreme case, films are deposited with ions in the energy range 20--50 eV, and at the other extreme, ions can be implanted with high energy (100 keV or more) without film deposition. Novel features of the technique include the use of improved macroparticle filters; the implementation of several plasma sources for multi-element surface modification; tuning of ion energy during implantation and deposition to tailor the substrate-film intermixed layer and structure of the growing film; simultaneous pulsing of the plasma potential (positive) and substrate bias (negative) with a modified Marx generator; and the use of high ion charge states.

  19. Ion Mobility Spectrometry of Heavy Metals.

    PubMed

    Ilbeigi, Vahideh; Valadbeigi, Younes; Tabrizchi, Mahmoud

    2016-07-19

    A simple, fast, and inexpensive method was developed for detecting heavy metals via the ion mobility spectrometry (IMS) in the negative mode. In this method, Cl(-) ion produced by the thermal ionization of NaCl is employed as the dopant or the ionizing reagent to ionize heavy metals. In practice, a solution of mixed heavy metals and NaCl salts was directly deposited on a Nichrome filament and electrically heated to vaporize the salts. This produced the IMS spectra of several heavy-metal salts, including CdCl2, ZnSO4, NiCl2, HgSO4, HgCl2, PbI2, and Pb(Ac)2. For each heavy metal (M), one or two major peaks were observed, which were attributed to M·Cl(-) or [M·NaCl]Cl(-)complexes. The method proved to be useful for the analysis of mixed heavy metals. The absolute detection limits measured for ZnSO4 and HgSO4 were 0.1 and 0.05 μg, respectively. PMID:27321408

  20. The role of metal ion-ligand interactions during divalent metal ion adsorption.

    PubMed

    Eldridge, Daniel S; Crawford, Russell J; Harding, Ian H

    2015-09-15

    A suite of seven different divalent metal ions (Ca(II), Cd(II), Cu(II), Mg(II), Ni(II), Pb(II), Zn(II)) was adsorbed from solution onto two Fe2O3 samples, quartz SiO2 and three different amphoteric polystyrene latices (containing amine and carboxyl functional groups). For the metal oxides, a high correlation was observed between the pH at which 50% of the metal was removed from solution (pH50) and the first hydrolysis constant for the metal ion (pK1). For the polystyrene latices, a much higher correlation was observed between the pH50 and pKc (equilibrium constant describing metal-carboxyl affinity) as opposed to pK1. These observations provide evidence of a strong relationship that exists between a metal's affinity for a particular ligand in solution and for that metal ion's affinity for the same ligand present as part of an adsorbing surface. The isoelectric point of the amphoteric latex surface can be increased by decreasing the carboxyl content of the latex surface. For all 7 metal ions, this resulted in a substantial decrease, for any given pH, in adsorption. We suggest that this may be partly due to the decreased carboxyl content, but is dominantly attributable to the presence of less favorable electrostatic conditions. This, in turn, demonstrates that electrostatics play a controlling role in metal ion adsorption onto amphoteric latex surfaces and, in addition to the nature of the metal ion, also controls the pH at which adsorption takes place. PMID:26001134

  1. Metallic ions in cometary comae and plasma tails

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.; Axford, W. I.

    1986-06-01

    A surprising result of the International Cometary Explorer (ICE) observations of the comet Giacobini-Zinner was the detection of ions of mass 23-24 AMU with a relatively high abundance. According to the experiments, these ions may be either Na(+) or C2(+), if not both. It is suggested here that the detected ions may indeed be in part Na(+) and/or Mg(+), and that these and other metallic ions, especially Si(+) and Fe(+), may be an important component of the cometary ionosphere and central plasma tail. The reasons are similar in principle to those which account for the prevalence of such ions in sporadic E layers in the terrestrial ionosphere, notably the comparatively short timescales for ionization of their neutral parent atoms and the large difference between the rates of dissociative and radiative recombination.

  2. Data mining of metal ion environments present in protein structures.

    PubMed

    Zheng, Heping; Chruszcz, Maksymilian; Lasota, Piotr; Lebioda, Lukasz; Minor, Wladek

    2008-09-01

    Analysis of metal-protein interaction distances, coordination numbers, B-factors (displacement parameters), and occupancies of metal-binding sites in protein structures determined by X-ray crystallography and deposited in the PDB shows many unusual values and unexpected correlations. By measuring the frequency of each amino acid in metal ion-binding sites, the positive or negative preferences of each residue for each type of cation were identified. Our approach may be used for fast identification of metal-binding structural motifs that cannot be identified on the basis of sequence similarity alone. The analysis compares data derived separately from high and medium-resolution structures from the PDB with those from very high-resolution small-molecule structures in the Cambridge Structural Database (CSD). For high-resolution protein structures, the distribution of metal-protein or metal-water interaction distances agrees quite well with data from CSD, but the distribution is unrealistically wide for medium (2.0-2.5A) resolution data. Our analysis of cation B-factors versus average B-factors of atoms in the cation environment reveals substantial numbers of structures contain either an incorrect metal ion assignment or an unusual coordination pattern. Correlation between data resolution and completeness of the metal coordination spheres is also found. PMID:18614239

  3. Data mining of metal ion environments present in protein structures

    PubMed Central

    Zheng, Heping; Chruszcz, Maksymilian; Lasota, Piotr; Lebioda, Lukasz; Minor, Wladek

    2010-01-01

    Analysis of metal-protein interaction distances, coordination numbers, B-factors (displacement parameters), and occupancies of metal binding sites in protein structures determined by X-ray crystallography and deposited in the PDB shows many unusual values and unexpected correlations. By measuring the frequency of each amino acid in metal ion binding sites, the positive or negative preferences of each residue for each type of cation were identified. Our approach may be used for fast identification of metal-binding structural motifs that cannot be identified on the basis of sequence similarity alone. The analysis compares data derived separately from high and medium resolution structures from the PDB with those from very high resolution small-molecule structures in the Cambridge Structural Database (CSD). For high resolution protein structures, the distribution of metal-protein or metal-water interaction distances agrees quite well with data from CSD, but the distribution is unrealistically wide for medium (2.0 – 2.5 Å) resolution data. Our analysis of cation B-factors versus average B-factors of atoms in the cation environment reveals substantial numbers of structures contain either an incorrect metal ion assignment or an unusual coordination pattern. Correlation between data resolution and completeness of the metal coordination spheres is also found. PMID:18614239

  4. Complexing of metal ions by humic substances

    SciTech Connect

    Bryan, N.D.; Zhang, Y.; Jones, M.N.

    1995-12-31

    The interaction of metal ions with humic substances is being studied using two different techniques. UV-scanning ultracentrifugation is being used to determine molecular weights and to investigate changes in aggregation brought about by metal ion complexation. The relationship between cation charge and conformation of the humic ligands is also being investigated. The complexation of actinide elements (U, Np, Pu, Am) by humic substances from soils contaminated by both natural processes and by low-level effluent releases is also being studied. Gel permeation chromatography has been used to show both that different fractions of humic substances vary greatly in their effectiveness as ligands and that different actinide elements associate with different fractions. These studies have also shown that uranium desorption is kinetically controlled by humic substances.

  5. Interplay of metal ions and urease.

    PubMed

    Carter, Eric L; Flugga, Nicholas; Boer, Jodi L; Mulrooney, Scott B; Hausinger, Robert P

    2009-01-01

    Urease, the first enzyme to be crystallized, contains a dinuclear nickel metallocenter that catalyzes the decomposition of urea to produce ammonia, a reaction of great agricultural and medical importance. Several mechanisms of urease catalysis have been proposed on the basis of enzyme crystal structures, model complexes, and computational efforts, but the precise steps in catalysis and the requirement of nickel versus other metals remain unclear. Purified bacterial urease is partially activated via incubation with carbon dioxide plus nickel ions; however, in vitro activation also has been achieved with manganese and cobalt. In vivo activation of most ureases requires accessory proteins that function as nickel metallochaperones and GTP-dependent molecular chaperones or play other roles in the maturation process. In addition, some microorganisms control their levels of urease by metal ion-dependent regulatory mechanisms. PMID:20046957

  6. Metal ion bombardment of onion skin cell wall

    SciTech Connect

    Sangyuenyongpipat, S.; Vilaithong, T.; Yu, L.D.; Verdaguer, A.; Ratera, I.; Ogletree, D.F.; Monteiro, O.R.; Brown, I.G.

    2004-05-10

    Ion bombardment of living cellular material is a novel subfield of ion beam surface modification that is receiving growing attention from the ion beam and biological communities. Although it has been demonstrated that the technique is sound, in that an adequate fraction of the living cells can survive both the vacuum environment and energetic ion bombardment, there remains much uncertainty about the process details. Here we report on our observations of onion skin cells that were subjected to ion implantation, and propose some possible physical models that tend to support the experimental results. The ion beams used were metallic (Mg, Ti, Fe, Ni, Cu), mean ion energy was typically 30keV, and the implantation fluence was in the range 1014 1016 ions/cm2. The cells were viewed using Atomic Force Microscopy, revealing the formation of microcrater-like structures due to ion bombardment. The implantation depth profile was measured with Rutherford backscattering spectrometry and compared to the results of the TRIM, T-DYN and PROFILE computer codes.

  7. Potentiometric titration of metal ions in ethanol.

    PubMed

    Gibson, Graham T T; Mohamed, Mark F; Neverov, Alexei A; Brown, R S

    2006-09-18

    The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented. PMID:16961382

  8. Metal hydrides for lithium-ion batteries.

    PubMed

    Oumellal, Y; Rougier, A; Nazri, G A; Tarascon, J-M; Aymard, L

    2008-11-01

    Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH(2) with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH(2) electrode shows a large, reversible capacity of 1,480 mAh g(-1) at an average voltage of 0.5 V versus Li(+)/Li(o) which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH(2). Furthermore, the reaction is not specific to MgH(2), as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH(2), which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries. PMID:18849978

  9. Metal assisted focused-ion beam nanopatterning

    NASA Astrophysics Data System (ADS)

    Kannegulla, Akash; Cheng, Li-Jing

    2016-09-01

    Focused-ion beam milling is a versatile technique for maskless nanofabrication. However, the nonuniform ion beam profile and material redeposition tend to disfigure the surface morphology near the milling areas and degrade the fidelity of nanoscale pattern transfer, limiting the applicability of the technique. The ion-beam induced damage can deteriorate the performance of photonic devices and hinders the precision of template fabrication for nanoimprint lithography. To solve the issue, we present a metal assisted focused-ion beam (MAFIB) process in which a removable sacrificial aluminum layer is utilized to protect the working material. The new technique ensures smooth surfaces and fine milling edges; in addition, it permits direct formation of v-shaped grooves with tunable angles on dielectric substrates or metal films, silver for instance, which are rarely achieved by using traditional nanolithography followed by anisotropic etching processes. MAFIB was successfully demonstrated to directly create nanopatterns on different types of substrates with high fidelity and reproducibility. The technique provides the capability and flexibility necessary to fabricate nanophotonic devices and nanoimprint templates.

  10. Metal assisted focused-ion beam nanopatterning.

    PubMed

    Kannegulla, Akash; Cheng, Li-Jing

    2016-09-01

    Focused-ion beam milling is a versatile technique for maskless nanofabrication. However, the nonuniform ion beam profile and material redeposition tend to disfigure the surface morphology near the milling areas and degrade the fidelity of nanoscale pattern transfer, limiting the applicability of the technique. The ion-beam induced damage can deteriorate the performance of photonic devices and hinders the precision of template fabrication for nanoimprint lithography. To solve the issue, we present a metal assisted focused-ion beam (MAFIB) process in which a removable sacrificial aluminum layer is utilized to protect the working material. The new technique ensures smooth surfaces and fine milling edges; in addition, it permits direct formation of v-shaped grooves with tunable angles on dielectric substrates or metal films, silver for instance, which are rarely achieved by using traditional nanolithography followed by anisotropic etching processes. MAFIB was successfully demonstrated to directly create nanopatterns on different types of substrates with high fidelity and reproducibility. The technique provides the capability and flexibility necessary to fabricate nanophotonic devices and nanoimprint templates. PMID:27479713

  11. Incorporation of metal ions into polyimides

    NASA Technical Reports Server (NTRS)

    Taylor, L. T.; Carver, V. C.; Furtsch, T. A.; Saint Clair, A. K.

    1980-01-01

    The effects of the incorporation of metal ions into various polyimides on polyimide properties are investigated. Polyimide films derived from 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BDTA) 3,3'-diaminobenzophenone (m,m'-DABP), 4,4'-diaminobenzophenone (p,p'-DABP) or 4,4'-oxydianiline were prepared with the concurrent addition of approximately 20 metals in a variety of forms. In general, it is found that the films derived from BDTA + p,p'-DABP were brittle and of poor quality, with brittle films also produced in most of the BDTA + m, m'-DABP polyimides regardless of whether the added metal was hydrate or anhydrous. Thermomechanical analysis, torsional braid analysis, thermal gravimetric analysis, infrared spectral analysis and isothermal studies on many of the polyimide films produced indicate that the softening temperature is generally increased upon the addition of metal ions, at the expense of thermal stability, while no changes in chemical functionality are observed. The best system studied in regard to polymer property enhancement appears to be tri(acetylacetonato)aluminum(III) added to the m, m'-DABP polyamide, which has been found to exhibit four times the lap shear strength of the polyimide alone.

  12. Transparent monolithic metal ion containing nanophase aerogels

    SciTech Connect

    Risen, W. M., Jr.; Hu, X.; Ji, S.; Littrell, K.

    1999-12-01

    The formation of monolithic and transparent transition metal containing aerogels has been achieved through cooperative interactions of high molecular weight functionalized carbohydrates and silica precursors, which strongly influence the kinetics of gelation. After initial gelation, subsequent modification of the ligating character of the system, coordination of the group VIII metal ions, and supercritical extraction afford the aerogels. The structures at the nanophase level have been probed by photon and electron transmission and neutron scattering techniques to help elucidate the basis for structural integrity together with the small entity sizes that permit transparency in the visible range. They also help with understanding the chemical reactivities of the metal-containing sites in these very high surface area materials. These results are discussed in connection with new reaction studies.

  13. On the Metal Ion Selectivity of Oxoacid Extractants

    SciTech Connect

    Hay, Benjamin; Chagnes, Alexandre; Cote, Gerard

    2013-01-01

    Relationships between metal chelate stability, ligand basicity, and metal ion acidity are reviewed and the general applicability is illustrated by linear correlations between aqueous stability constants and ligand pKa values for 35 metals with 26 ligands. The results confirm that most individual ligands of this type exhibit a stability ordering that correlates with the Lewis acidity of the metal ion. It is concluded that the general metal ion selectivity exhibited by liquid-liquid oxoacid extractants such as carboxylic acids, -diketones, and alkylphosphoric acids reflects the intrinsic affinity of the metal ion for the negative oxygen donor ligand.

  14. Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source

    SciTech Connect

    Thorn, A.; Ritter, E.; Zschornack, G.; Ullmann, F.; Pilz, W.; Bischoff, L.

    2012-02-15

    We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au{sup 60+}. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

  15. Liquid metal ion source assembly for external ion injection into an electron string ion source (ESIS)

    NASA Astrophysics Data System (ADS)

    Segal, M. J.; Bark, R. A.; Thomae, R.; Donets, E. E.; Donets, E. D.; Boytsov, A.; Ponkin, D.; Ramsdorf, A.

    2016-02-01

    An assembly for a commercial Ga+ liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga+ ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga+ and Au+ ion beams will be reported as well.

  16. Comparative inhibition by hard and soft metal ions of steroid-binding capacity of renal mineralocorticoid receptor cross-linked to the 90-kDa heat-shock protein heterocomplex.

    PubMed Central

    Galigniana, M D; Piwien-Pilipuk, G

    1999-01-01

    We analysed the inhibitory effects in vitro and in vivo of several metal ions on aldosterone binding to the rat kidney mineralocorticoid receptor with the purpose of assessing possible toxic effects of those ions on sodium retention, as well as to obtain information on receptor structural requirements for ligand binding. For the assays in vitro, the inhibitory effects of 20 metal ions were analysed on steroid-binding capacity for renal receptor cross-linked to 90-kDa heat-shock protein (hsp90) by pretreatment with dimethyl pimelimidate. Cross-linking prevented the artifactual dissociation of hsp90 (and, consequently, the loss of steroid binding) from the mineralocorticoid receptor due to the presence of high concentrations of salt in the incubation medium. Cross-linked heterocomplex showed no difference in ligand specificity and affinity with respect to native receptor, but increased stability upon thermal- or ionic-strength-induced destabilization was observed. Treatments in vitro with metal ions in the range 10(-8)-10(-1) M resulted in a differential inhibitory effect for each particular ion on aldosterone binding. Using the negative logarithm of metal concentration for 50% inhibition, the ions could be correlated with their Klopman hardness constants. The analysis of this relationship led us to postulate three types of reaction: with thiol, imidazole and carboxyl groups. The essential role played by these residues in steroid binding was confirmed by chemical modification of cysteines with dithionitrobenzoic acid, histidines with diethyl pyrocarbonate and acidic amino acids with Woodward's reagent (N-ethyl-5-phenylisoxazolium-3'-sulphonate). Importantly, the toxic effects of some metal ions were also observed by treatments in vivo of adrenalectomized rats on both steroid-binding capacity and aldosterone-dependent sodium-retaining properties. We suggest that those amino acid residues are involved in the activation process of the mineralocorticoid receptor upon

  17. Metal ion binding to iron oxides

    NASA Astrophysics Data System (ADS)

    Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

    2006-06-01

    The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

  18. Rational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Raymond, Kenneth N.

    2000-09-30

    The discriminate bonding of metal ions is a challenge to the synthetic chemist and a phenomenon of considerable practical importance.1 An important feature of many technical applications is the specific or preferential binding of a single metal ion in the presence of many metals. Examples range from large-volume uses (e.g. ferric EDTA as a plant food, calcium complexing agents as water softeners or anticaking formulations) to very high technology applications (technetium complexation in radiopharmaceuticals, synthetic metalloenzymes). We are interested in efficient and discriminate binding of actinides for waste stream remediation. Actinides represent a major and long-lived contaminant in nuclear waste. While the separation of actinides from other radioactive components of waste, such as Sr and Cs, is relatively well established, the separation of actinides from each other and in complex solutions (e.g. those found in tank wastes) is not as well resolved. The challenge of designing metal-specific (actinide) ligands is facilitated by examples from nature. Bacteria synthesize Fe(III)-specific ligands, called siderophores, to sequester Fe(III) from the environment and return it to the cell. The similarities between Fe(III) and Pu(IV) (their charge-to-size ratios and acidity), make the siderophores prototypical for designing actinide-specific ligands. The chelating groups present in siderophores are usually hydroxamic acids and catecholamides. We have developed derivatives of these natural products which have improved properties. The catechol derivatives are the 2,3-dihydroxyterephthalamides (TAMs), and 3,4-dihydroxysulfonamides (SFAMs), and the hydroxamic acid derivatives are three isomers of hydroxypyridinones, 1,2- HOPO, 3,2-HOPO, and 3,4-HOPO. All of these ligands are attached to molecular backbones by amides and a very important feature of HOPO and CAM ligands is a strong hydrogen bonds formed between the amide proton and the adjacent phenolic oxygen in the metal

  19. Lithium metal doped electrodes for lithium-ion rechargeable chemistry

    DOEpatents

    Liu, Gao; Battaglia, Vince; Wang, Lei

    2016-09-13

    An embodiment of the invention combines the superior performance of a polyvinylidene difluoride (PVDF) or polyethyleneoxide (POE) binder, the strong binding force of a styrene-butadiene (SBR) binder, and a source of lithium ions in the form of solid lithium metal powder (SLMP) to form an electrode system that has improved performance as compared to PVDF/SBR binder based electrodes. This invention will provide a new way to achieve improved results at a much reduced cost.

  20. Substrate Profile and Metal-ion Selectivity of Human Divalent Metal-ion Transporter-1*

    PubMed Central

    Illing, Anthony C.; Shawki, Ali; Cunningham, Christopher L.; Mackenzie, Bryan

    2012-01-01

    Divalent metal-ion transporter-1 (DMT1) is a H+-coupled metal-ion transporter that plays essential roles in iron homeostasis. DMT1 exhibits reactivity (based on evoked currents) with a broad range of metal ions; however, direct measurement of transport is lacking for many of its potential substrates. We performed a comprehensive substrate-profile analysis for human DMT1 expressed in RNA-injected Xenopus oocytes by using radiotracer assays and the continuous measurement of transport by fluorescence with the metal-sensitive PhenGreen SK fluorophore. We provide validation for the use of PhenGreen SK fluorescence quenching as a reporter of cellular metal-ion uptake. We determined metal-ion selectivity under fixed conditions using the voltage clamp. Radiotracer and continuous measurement of transport by fluorescence assays revealed that DMT1 mediates the transport of several metal ions that were ranked in selectivity by using the ratio Imax/K0.5 (determined from evoked currents at −70 mV): Cd2+ > Fe2+ > Co2+, Mn2+ ≫ Zn2+, Ni2+, VO2+. DMT1 expression did not stimulate the transport of Cr2+, Cr3+, Cu+, Cu2+, Fe3+, Ga3+, Hg2+, or VO+. 55Fe2+ transport was competitively inhibited by Co2+ and Mn2+. Zn2+ only weakly inhibited 55Fe2+ transport. Our data reveal that DMT1 selects Fe2+ over its other physiological substrates and provides a basis for predicting the contribution of DMT1 to intestinal, nasal, and pulmonary absorption of metal ions and their cellular uptake in other tissues. Whereas DMT1 is a likely route of entry for the toxic heavy metal cadmium, and may serve the metabolism of cobalt, manganese, and vanadium, we predict that DMT1 should contribute little if at all to the absorption or uptake of zinc. The conclusion in previous reports that copper is a substrate of DMT1 is not supported. PMID:22736759

  1. Some aspects of metallic ion chemistry and dynamics in the mesosphere and thermosphere

    NASA Technical Reports Server (NTRS)

    Mathews, J. D.

    1987-01-01

    The relationship between the formation of sporadic layers of metallic ion and the dumping of these ions into the upper mesosphere is discussed in terms of the tidal wind, classical (i.e., windshear) and other more complex, perhaps highly nonlinear layer formation mechanisms, and a possible circulation mechanism for these ions. Optical, incoherent scatter radar, rocket, and satellite derived evidence for various layer formation mechanisms and for the metallic ion circulation system is reviewed. The results of simple one dimensional numerical model calculations of sporadic E and intermediate layer formation are presented along with suggestions for more advanced models of intense or blanketing sporadic E. The flux of metallic ions dumped by the tidal wind system into the mesosphere is estimated and compared with estimates of total particle flux of meteoric origin. Possible effects of the metallic ion flux and of meteoric dust on D region ion chemistry are discussed.

  2. Antifungal Properties of Electrically Generated Metallic Ions

    PubMed Central

    Berger, T. J.; Spadaro, J. A.; Bierman, Richard; Chapin, S. E.; Becker, R. O.

    1976-01-01

    A qualitative and quantitative investigation was undertaken to study the susceptibility of unicellular eucaryotic organisms (yeasts) to metallic cations generated by low levels of direct current. Results were characteristic of effects obtained previously using clinical and standard bacteria test organisms. The present study demonstrated that anodic silver (Ag+) at low direct currents had inhibitory and fungicidal properties. Broth dilution susceptibility tests were made on several species of Candida and one species of Torulopsis. Growth in all isolates was inhibited by concentrations of electrically generated silver ions between 0.5 and 4.7 μg/ml, and silver exhibited fungicidal properties at concentrations as low as 1.9 μg/ml. The inhibitory and fungicidal concentrations of electrically generated silver ions are lower than those reported for other silver compounds. Images PMID:1034467

  3. Metal Ion Intercalated graphitic as Transparent Electrodes

    NASA Astrophysics Data System (ADS)

    Wan, Jiayu; Bao, Wenzhong; Gu, Feng; Fuhrer, Michael; Hu, Liangbing; UMD Team

    To best utilize the performance of graphene based transparent electrodes, we novelized Li-ion intercalation in graphene, and achieved highest performance of carbon based transparent electrodes. Transmission as high as 91.7% with a sheet resistance of 3.0 ohm/sq is achieved for 19-layer LiC6, significantly higher than any other continuous transparent electrodes. The unconventional modification of ultrathin graphite optoelectronic properties is explained by the suppression of interband optical transitions and a small intraband Drude conductivity near the interband edge. To achieve low cost, large scale graphene-based transparent electrodes, we further developed Na-ion intercalated printed reduced graphene oxide (RGO) film. The larger layer-layer distance of RGO allows Na-ion intercalation, leading to simultaneously much higher DC conductivity and higher optical transmittance. Typical increase of transmittance from 36% to 79% and decrease of sheet resistance from 83 kohms/sq to 311 ohms/sq in the printed network was observed. This study demonstrated the great potential of metal-ion intercalation to improve the performance of graphene-based materials for transparent conductor applications.

  4. Comparative toxicity of five metals on various biological subjects

    SciTech Connect

    Fargasova, A. )

    1994-08-01

    Environmental contaminants, including metals, can have toxic effects on many different organisms and affect biological processes at cellular, population, community and ecosystem levels of organization. Metals are of particular interest because they may have a positive effect as micronutrients at low concentrations as well as a toxic effect at higher levels. Numerous efforts have been made to correlate and predict metal-ion toxicities on various aquatic and terrestrial species, according to the physical and chemical properties of the metals. The acute and chronic toxicities of metals have been studied on many freshwater organisms and also on plants. The water flea, Daphnia magna, an important freshwater zooplankter, is a useful test species to study sensitivity to environmental toxicants and has been recognized as a general representative for other freshwater animals. As Khangarot described, little information is available on the effects of metals to tubificid worms, which are widely distributed in the aquatic environment and are useful indicators of varying degrees of aquatic pollution. Most recent hazard evaluation programs recommend algal toxicity tests for initial evaluations of chemicals that are expected to reach surface waters and that have suspected or unknown phytotoxic properties. For higher plants, the accumulation of metals, especially cadmium, was tested when plants grew in sewage sludge-amended soils or in soils of cadmium residues form phosphate fertilizers. No reports were available indicating the effects of these metals on seed germination and root growth. This study was conducted to determine the acute toxicological effects of some metals (As, Pb, Cr, Hg, Cd) on four biological subjects (tubificid worms, Daphnia magna sp., Scenedesmus quadricauda, seeds of Sinapis alba) and to compare their sensitivity to individual test metals. 16 refs., 1 tab.

  5. The 2007 Otto Aufranc Award. Ceramic-on-metal hip arthroplasties: a comparative in vitro and in vivo study.

    PubMed

    Williams, Sophie; Schepers, Anton; Isaac, Graham; Hardaker, Cath; Ingham, Eileen; van der Jagt, Dick; Breckon, Anke; Fisher, John

    2007-12-01

    The performance of novel ceramic-on-metal bearing couples has been compared with metal-on-metal and ceramic-on-ceramic bearing couples in laboratory and short-term clinical studies. Laboratory studies compared ceramic-on-metal with metal-on-metal and ceramic-on-ceramic bearings with diameters of 28 and 36 mm under standard conditions and under adverse conditions with head loading on the rim of the cup. Clinical studies compared metal ion levels in ceramic-on-metal with metal-on-metal, ceramic-on-ceramic, and ceramic-on-polyethylene bearings in a randomized prospective study. In the laboratory studies, friction, wear, and ion levels were lower in ceramic-on-metal bearings compared with metal-on-metal, with results similar to ceramic-on-ceramic couples. Under adverse conditions and rim loading, all bearings showed increased wear with lower wear and absence of stripe wear in ceramic-on-metal compared with metal-on-metal bearings. Short-term studies in 31 patients at 6 months revealed lower metal ion levels (cobalt and chromium) in those with ceramic-on-metal compared with metal-on-metal bearings. PMID:18090468

  6. Behavior of metal ions in bioelectrochemical systems: A review

    NASA Astrophysics Data System (ADS)

    Lu, Zhihao; Chang, Dingming; Ma, Jingxing; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

    2015-02-01

    Bioelectrochemical systems (BESs) have been focused on by many researchers to treat wastewater and recover energy or valuable chemicals from wastes. In BESs, metal ions play an important role in the conductivity of solution, reactors' internal resistance, power generation, chemical production and activity of microorganisms. Additionally, the metal ions are also involved in anodic or cathodic reaction processes directly or indirectly in BESs. This paper reviews the behavior of metal ions in BESs, including (1) increase of the conductivity of electrolyte and decrease of internal resistance, (2) transfer for desalination, (3) enhancement or inhibition of the biocatalysis in anode, (4) improvement of cathodic performance by metal ions through electron acceptance or catalysis in cathodic process and (5) behavior of metal ions on membranes. Moreover, the perspectives of BESs removing heavy metal ions in wastewater or solid waste are discussed to realize recovery, reduction and detoxification simultaneously.

  7. Metal ion cooperativity in ribozyme cleavage of RNA

    PubMed Central

    Brännvall, Mathias; Kirsebom, Leif A.

    2001-01-01

    Combinations of chemical and genetic approaches were used to study the function of divalent metal ions in cleavage of RNA by the ribozyme RNase P RNA. We show that different divalent metal ions have differential effects on cleavage site recognition and rescue of cleavage activity by mixing divalent metal ions that do not promote cleavage by themselves. We conclude that efficient and correct cleavage is the result of cooperativity between divalent metal ions bound at different sites in the RNase P RNA-substrate complex. Complementation of a mutant RNase P RNA phenotype as a result of divalent metal ion replacement is demonstrated also. This finding together with other data indicate that one of the metal ions involved in this cooperativity is positioned near the cleavage site. The possibility that the Mg2+/Ca2+ ratio might regulate the activity of biocatalysts that depend on RNA for activity is discussed. PMID:11606743

  8. Separation of traces of metal ions from sodium matrices

    NASA Technical Reports Server (NTRS)

    Korkisch, J.; Orlandini, K. A.

    1969-01-01

    Method for isolating metal ion traces from sodium matrices consists of two extractions and an ion exchange step. Extraction is accomplished by using 2-thenoyltrifluoracetone and dithizone followed by cation exchange.

  9. Biosorption of metal ions from aqueous solutions

    SciTech Connect

    Chen, Jiaping; Yiacoumi, Sotira

    1997-01-01

    Copper biosorption from aqueous solutions by calcium alginate is reported in this paper. The experimental section includes potentiometric titrations of biosorbents, batch equilibrium and kinetic studies of copper biosorption, as well as fixed-bed biosorption experiments. The potentiometric titration results show that the surface charge increases with decreasing pH. The biosorption of copper strongly depends on solution pH; the metal ion binding increases from 0 to 90 percent in pH ranging from 1.5 to 5.0. In addition, a decrease in ionic strength results in an increase of copper ion removal. Kinetic studies indicate that mass transfer plays an important role in the biosorption rate. Furthermore, a fixed-bed biosorption experiment shows that calcium alginate has a significant capacity for copper ion removal. The two-pK Basic Stem model successfully represents the surface charge and equilibrium biosorption experimental data. The calculation results demonstrate that the copper removal may result from the binding of free copper and its hydroxide with surface functional groups of the biosorbents.

  10. Comet Encke: Meteor metallic ion identification by mass spectrometer

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Aikin, A. C.

    1973-01-01

    Positive metallic ions have been measured in the earth's atmosphere between 85 and 120 km, during the period of the beta Taurids meteor shower, which is associated with Comet Encke. The ions originate during and following ablation of extraterrestrial debris by the earth's atmosphere. The enhancement of metal ion density during meteor showers is primary evidence for their extraterrestrial origin. The present results were obtained from a rocket-borne ion mass spectrometer.

  11. THE ROLES OF METAL IONS IN REGULATION BY RIBOSWITCHES

    PubMed Central

    2012-01-01

    Metal ions are required by all organisms in order to execute an array of essential molecular functions. They play a critical role in many catalytic mechanisms and structural properties. Proper homeostasis of ions is critical; levels that are aberrantly low or high are deleterious to cellular physiology. To maintain stable intracellular pools, metal ion-sensing regulatory (metalloregulatory) proteins couple metal ion concentration fluctuations with expression of genes encoding for cation transport or sequestration. However, these transcriptional-based regulatory strategies are not the only mechanisms by which organisms coordinate metal ions with gene expression. Intriguingly, a few classes of signal-responsive RNA elements have also been discovered to function as metalloregulatory agents. This suggests that RNA-based regulatory strategies can be precisely tuned to intracellular metal ion pools, functionally akin to metalloregulatory proteins. In addition to these metal-sensing regulatory RNAs, there is a yet broader role for metal ions in directly assisting the structural integrity of other signal-responsive regulatory RNA elements. In this chapter, we discuss how the intimate physicochemical relationship between metal ions and nucleic acids is important for the structure and function of metal ion- and metabolite-sensing regulatory RNAs. PMID:22010271

  12. Plasma immersion ion implantation for reducing metal ion release

    SciTech Connect

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J.

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  13. A fluorometric paper-based sensor array for the discrimination of heavy-metal ions.

    PubMed

    Feng, Liang; Li, Hui; Niu, Li-Ya; Guan, Ying-Shi; Duan, Chun-Feng; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-04-15

    A fluorometric paper-based sensor array has been developed for the sensitive and convenient determination of seven heavy-metal ions at their wastewater discharge standard concentrations. Combining with nine cross-reactive BODIPY fluorescent indicators and array technologies-based pattern-recognition, we have obtained the discrimination capability of seven different heavy-metal ions at their wastewater discharge standard concentrations. After the immobilization of indicators and the enrichment of analytes, identification of the heavy-metal ions was readily acquired using a standard chemometric approach. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative estimation of the heavy-metal ion concentration was obtained by comparing color changes with a set of known concentrations. The sensor array was tentatively investigated in spiked tap water and sea water, and showed possible feasibility for real sample testing. PMID:23601876

  14. Fluorescence imaging of metal ions implicated in diseases.

    PubMed

    Qian, Xuhong; Xu, Zhaochao

    2015-07-21

    Metal ions play an important role in various biological processes, their abnormal homeostasis in cells is related to many diseases, such as neurodegenerative disease, cancer and diabetes. Fluorescent imaging offers a unique route to detect metal ions in cells via a contactless and damage-free way with high spatial and temporal fidelity. Consequently, it represents a promising method to advance the understanding of physiological and pathological functions of metal ions in cell biology. In this highlight article, we will discuss recent advances in fluorescent imaging of metal ions by small-molecule sensors for understanding the role of metals in related diseases. We will also discuss challenges and opportunities for the design of small-molecule sensors for fluorescent detection of cellular metal ions as a potential method for disease diagnosis. PMID:25556818

  15. Paramagnetic metal ions in pulsed ESR distance distribution measurements.

    PubMed

    Ji, Ming; Ruthstein, Sharon; Saxena, Sunil

    2014-02-18

    The use of pulsed electron spin resonance (ESR) to measure interspin distance distributions has advanced biophysical research. The three major techniques that use pulsed ESR are relaxation rate based distance measurements, double quantum coherence (DQC), and double electron electron resonance (DEER). Among these methods, the DEER technique has become particularly popular largely because it is easy to implement on commercial instruments and because programs are available to analyze experimental data. Researchers have widely used DEER to measure the structure and conformational dynamics of molecules labeled with the methanethiosulfonate spin label (MTSSL). Recently, researchers have exploited endogenously bound paramagnetic metal ions as spin probes as a way to determine structural constraints in metalloproteins. In this context Cu(2+) has served as a useful paramagnetic metal probe at X-band for DEER based distance measurements. Sample preparation is simple, and a coordinated-Cu(2+) ion offers limited spatial flexibility, making it an attractive probe for DEER experiments. On the other hand, Cu(2+) has a broad absorption ESR spectrum at low temperature, which leads to two potential complications. First, the Cu(2+)-based DEER time domain data has lower signal to noise ratio compared with MTSSL. Second, accurate distance distribution analysis often requires high-quality experimental data at different external magnetic fields or with different frequency offsets. In this Account, we summarize characteristics of Cu(2+)-based DEER distance distribution measurements and data analysis methods. We highlight a novel application of such measurements in a protein-DNA complex to identify the metal ion binding site and to elucidate its chemical mechanism of function. We also survey the progress of research on other metal ions in high frequency DEER experiments. PMID:24289139

  16. Ion flotation behaviour of thirty-one metal ions in mixed hydrochloric/nitric acid solutions.

    PubMed

    Hualing, D; Zhide, H

    1989-06-01

    The ion flotation of 31 metal ions in hydrochloric/nitric acid solution with the cationic surfactant cetylpyridinium chloride was investigated. A 25-ml portion of 0.27-2.87 x 10(-4)M metal ion and 1.8-6.0 x 10(-4)M cetylpyridinium chloride solution in 0.17-3.4M acid mixture ([HCl]:[HNO(3)] = 2.4:1) was subjected to flotation in a cell, 22.5 cm high and 4.0 cm in diameter, for 5 min, with nitrogen bubbles. Ir(IV), Pt(IV), Ge(IV), Sn(IV), Bi(III), Au(III), Tl(III), Pd(II) and Sn(II) were floated from solution in 95-100% yield; Ru(III), Rh(III), Ir(III), Hg(II), Ag(I) and Tl(I) were partly floated, while Cr(VI), Ti(IV), Zr(IV), Ga(III), In(III), Fe(III), Sb(III), Al(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), CD(II) and Pb(II) were floated with less than 20% yield. The flotation behaviour of these metal ions in the mixed acid system was compared with that in hydrochloric acid. The flotation is more efficient in the mixed acid system. PMID:18964771

  17. Metal Ion Capture Mechanism of a Copper Metallochaperone.

    PubMed

    Chakravorty, Dhruva K; Li, Pengfei; Tran, Trang T; Bayse, Craig A; Merz, Kenneth M

    2016-01-26

    A novel cation-π interaction between the bound Cu(+) metal ion and Trp44 in the periplasmic Cu(+)/Ag(+) metallochaperone Escherichia coli CusF protects Cu(+) from the oxidative influence of the periplasm. In a popular model of metal ion transfer, a conformational change in the metal binding loop disrupts the cation-π interaction and moves Trp44 aside to provide access to the occluded metal ion binding site in an "open" conformation. In this study, our molecular dynamics simulations support this putative mechanism of metal ion transfer. We find that the apoprotein undergoes a transition back and forth from the crystallographically observed "closed" state to the hypothesized open conformation over multiple microseconds. In agreement with nuclear magnetic resonance data, our simulations show that similar transitions are prohibited in Cu(+)·CusF, suggesting that the conformational transitions are gated by a metal ion-mediated second-shell hydrogen bond between metal binding residue His36 and Asp37 of the metal binding loop region. Ab initio quantum mechanical calculations indicate that metal ion binding strengthens this interaction significantly, much like what is found in the case of other metalloproteins. The study builds toward a common evolutionary role of metal ion-mediated second-shell hydrogen bonds in metalloprotein structure and function. PMID:26690586

  18. Molecular Turnstiles Regulated by Metal Ions.

    PubMed

    Wang, Guangxia; Xiao, Hongmei; He, Jiaojiao; Xiang, Junfeng; Wang, Ying; Chen, Xuebo; Che, Yanke; Jiang, Hua

    2016-04-15

    A family of novel molecular turnstiles 1-3 composed of two stators with pyridyl binding sites and a different-sized triptycene rotor was synthesized. The molecular turnstiles behave in an open state at room temperature in the absence of metal ions but display significantly different closed states in the presence of Ag(+) and Pd(2+). The Ag(+)-mediated turnstiles 1-3Ag exhibited closed states but unreadable bistability at ambient temperature because the Ag(+)-mediated macrocyclic framework is not able to restrict the rotations of the rotors; while temperature was decreased, the macrocyclic frameworks became stable enough to halt the rotations of the rotors, eventually leading to the readable closed states for 1-3Ag. In contrast, Pd(2+)-mediated macrocyclic frameworks are stable, giving rise to a detectable closed state of turnstiles 1-3Pd in a wide range of temperatures. These findings have also been supported by DFT calculations. PMID:26986992

  19. Selective removal of alkali metal cations from multiply-charged ions via gas-phase ion/ion reactions using weakly coordinating anions.

    PubMed

    Luongo, Carl A; Bu, Jiexun; Burke, Nicole L; Gilbert, Joshua D; Prentice, Boone M; Cummings, Steven; Reed, Christopher A; McLuckey, Scott A

    2015-03-01

    Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 (-)), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 (-)). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations. PMID:25560986

  20. Selective Removal of Alkali Metal Cations from Multiply-Charged Ions via Gas-Phase Ion/Ion Reactions Using Weakly Coordinating Anions

    NASA Astrophysics Data System (ADS)

    Luongo, Carl A.; Bu, Jiexun; Burke, Nicole L.; Gilbert, Joshua D.; Prentice, Boone M.; Cummings, Steven; Reed, Christopher A.; McLuckey, Scott A.

    2015-03-01

    Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 -), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 -). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations.

  1. Multidiagnostics analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    SciTech Connect

    Anoop, K. K.; Polek, M. P.; Bruzzese, R.; Amoruso, S.; Harilal, Sivanandan S.

    2015-02-28

    The ions dynamics in ultrafast laser ablation of metals is studied over a fluence range spanning from the ablation threshold up to ~75 J/cm2 by means of three established diagnostic techniques. Langmuir probe, Faraday cup and spectrally resolved ICCD imaging simultaneously monitor the laser-produced plasma ions produced during ultrafast laser ablation of a copper target. The fluence dependence of ion yield is analyzed observing the occurrence of three different regimes. Moreover, the specific ion yield shows a maximum at about 4-5 J/cm2, followed by a gradual reduction and a transition to a high-fluence regime above ~50 J/cm2. The fluence variation of the copper ions angular distribution is also analyzed, observing a gradual increase of forward peaking of Cu ions for fluences up to ~10 J/cm2. Then, a broader ion component is observed at larger angles for fluences larger than ~10 J/cm2. Finally, an experimental characterization of the ions angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ~66 J/cm2. Interestingly, the ion emission from the volatile metals show a narrow forward peaked distribution and a high peak ion yield compared to the refractory metals. Moreover, the width of ion angular distributions presents a striking correlation with the peak ion yield.

  2. Electron Capture Dissociation of Trivalent Metal Ion-Peptide Complexes

    NASA Astrophysics Data System (ADS)

    Flick, Tawnya G.; Donald, William A.; Williams, Evan R.

    2013-02-01

    With electrospray ionization from aqueous solutions, trivalent metal ions readily adduct to small peptides resulting in formation of predominantly (peptide + MT - H)2+, where MT = La, Tm, Lu, Sm, Ho, Yb, Pm, Tb, or Eu, for peptides with molecular weights below ~1000 Da, and predominantly (peptide + MT)3+ for larger peptides. ECD of (peptide + MT - H)2+ results in extensive fragmentation from which nearly complete sequence information can be obtained, even for peptides for which only singly protonated ions are formed in the absence of the metal ions. ECD of these doubly charged complexes containing MT results in significantly higher electron capture efficiency and sequence coverage than peptide-divalent metal ion complexes that have the same net charge. Formation of salt-bridge structures in which the metal ion coordinates to a carboxylate group are favored even for (peptide + MT)3+. ECD of these latter complexes for large peptides results in electron capture by the protonation site located remotely from the metal ion and predominantly c/ z fragments for all metals, except Eu3+, which undergoes a one electron reduction and only loss of small neutral molecules and b/ y fragments are formed. These results indicate that solvation of the metal ion in these complexes is extensive, which results in the electrochemical properties of these metal ions being similar in both the peptide environment and in bulk water.

  3. Metal Ion Sensors Based on DNAzymes and Related DNA Molecules

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Bing; Kong, Rong-Mei; Lu, Yi

    2011-07-01

    Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+. In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes.

  4. Metal Ion Sensors Based on DNAzymes and Related DNA Molecules

    PubMed Central

    Kong, Rong-Mei

    2011-01-01

    Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+ In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes. PMID:21370984

  5. Biosorption of metal ions from aqueous solution and tannery effluent by Bacillus sp. FM1.

    PubMed

    Masood, Farhana; Malik, Abdul

    2011-01-01

    The metal binding capacity of Bacillus sp. FM1 isolated from soil irrigated with tannery effluent was assessed using synthetic metal solutions and tannery wastewater. Biosorption of Cr(VI) and Cu(II) ions from aqueous solutions using Bacillus was investigated as a function of pH, initial metal ion concentration and contact time. The optimum adsorption pH value observed for Cr(VI) and Cu(II) ions was 2 and 5, respectively. Metal ion uptake increased with increasing initial metal concentration but no significant difference was observed by increasing the time after 60 min. Maximum uptake capacity of chromium was estimated as 64.102 mg g(-1), and of copper to 78.125 mg g(-1). Equilibrium data were well described by the Langmuir and Freundlich adsorption relations. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. The application of Bacillus to remove Cr(VI) and Cu(II) in tannery effluent revealed that the biomass was capable of removing both the metal ions. However, the biosorption performance was slightly lower compared to that of synthetic metal solutions. Several factors may be responsible for this difference. However, the most important factor appears to be the presence of other contaminants such as anions, organics, and other trace metals in the effluent. PMID:22126236

  6. Structural insights into protein-metal ion partnerships.

    PubMed

    Barondeau, David P; Getzoff, Elizabeth D

    2004-12-01

    New metalloprotein structures continue to provide discoveries regarding protein-metal ion partnerships. Many recent structures reveal metal ion sites that control or are controlled by protein conformational change, including modulation by alternative splice variants and striking conformational changes. Only a few novel catalytic metal centers have been revealed recently, such as the surprising Ni-hook superoxide dismutase catalytic site and the cubane-like Mn(3)CaO(4) photosynthetic oxygen-evolving center. However, important new variations on old heme themes, breakthroughs in the fields of metal ion regulation and metallochaperones, and captivating insights into partnerships between proteins and minerals have also been described. Very high resolution metal site structures and metalloprotein design will be increasingly important in order to leverage the wealth of native metalloprotein structures into a deep understanding of metal ion site specificity and activity. PMID:15582401

  7. Impact of Protein-Metal Ion Interactions on the Crystallization of Silk Fibroin Protein

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Lu, Qiang; Kaplan, David; Cebe, Peggy

    2009-03-01

    Proteins can easily form bonds with a variety of metal ions, which provides many unique biological functions for the protein structures, and therefore controls the overall structural transformation of proteins. We use advanced thermal analysis methods such as temperature modulated differential scanning calorimetry and quasi-isothermal TMDSC, combined with Fourier transform infrared spectroscopy, and scanning electron microscopy, to investigate the protein-metallic ion interactions in Bombyx mori silk fibroin proteins. Silk samples were mixed with different metal ions (Ca^2+, K^+, Ma^2+, Na^+, Cu^2+, Mn^2+) with different mass ratios, and compared with the physical conditions in the silkworm gland. Results show that all metallic ions can directly affect the crystallization behavior and glass transition of silk fibroin. However, different ions tend to have different structural impact, including their role as plasticizer or anti-plasticizer. Detailed studies reveal important information allowing us better to understand the natural silk spinning and crystallization process.

  8. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  9. A self-sputtering ion source: A new approach to quiescent metal ion beams

    SciTech Connect

    Oks, Efim M.; Anders, Andre

    2009-09-03

    A new metal ion source is presented based on sustained self-sputtering plasma in a magnetron discharge. Metals exhibiting high self-sputtering yield like Cu, Ag, Zn, and Bi can be used in a high-power impulse magnetron sputtering (HIPIMS) discharge such that the plasma almost exclusively contains singly charged metal ions of the target material. The plasma and extracted ion beam are quiescent. The ion beams consist mostly of singly charged ions with a space-charge limited current density which reached about 10 mA/cm2 at an extraction voltage of 45 kV and a first gap spacing of 12 mm.

  10. A self-sputtering ion source: A new approach to quiescent metal ion beams

    SciTech Connect

    Oks, Efim

    2010-02-15

    A new metal ion source is presented based on sustained self-sputtering plasma in a magnetron discharge. Metals exhibiting high self-sputtering yield such as Cu, Ag, Zn, and Bi can be used in a high-power impulse magnetron sputtering discharge such that the plasma almost exclusively contains singly charged metal ions of the target material. The plasma and extracted ion beam are quiescent. The ion beams consist mostly of singly charged ions with a space-charge limited current density which reached about 10 mA/cm{sup 2} at an extraction voltage of 45 kV and a first gap spacing of 12 mm.

  11. Development of a lithium liquid metal ion source for MeV ion beam analysis

    SciTech Connect

    Read, P.M.; Maskrey, J.T.; Alton, G.D.

    1988-01-01

    Lithium liquid metal ion sources are an attractive complement to the existing gaseous ion sources that are extensively used for ion beam analysis. This is due in part to the high brightness of the liquid metal ion source and in part to the availability of a lithium ion beam. High brightness is of particular importance to MeV ion microprobes which are now approaching current density limitations on targets determined by the ion source. The availability of a lithium beam provides increased capabilities for hydrogen profiling and high resolution Rutherford backscattering spectrometry. This paper describes the design and performance of a lithium liquid metal ion source suitable for use on a 5MV Laddertron accelerator. Operational experience with the source and some of its uses for ion beam analysis are discussed. 8 refs., 2 figs.

  12. Impregnated-electrode-type liquid metal ion source

    NASA Astrophysics Data System (ADS)

    Ishikawa, J.; Gotoh, Y.; Tsuji, H.; Takagi, T.

    We have developed an impregnated-electrode-type liquid metal ion source whose tip is a sintered-porous structure made of a refractory metal such as tungsten. By this structure the ratio of the liquid metal surface area facing the vacuum to the volume is low, which decreases useless metal evaporation from the surface. The maximum vapour pressure of the metal in operation for this ion source is 10 -1-10 0 Torr, which is 2-3 orders of magnitude higher than that for the needle type. Therefore, useful metal ions such as Ga +, Au +, Ag +, In +, Si 2+, Ge 2+, and Sb 2+ can be extracted from single element metals or alloys. The porous structure of the tip has also an effect on the positive control of the liquid metal flow rate to the tip head. Thus, a stable operation with a high current of a few hundreds of μA can be obtained together with a low current high brightness ion beam. Therefore, this ion source is suitable not only for microfocusing but also for a general use as a metal ion source.

  13. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

    Bauman, A. J.; Weetal, H. H.; Weliky, N.

    1966-01-01

    Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

  14. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  15. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  16. Bioinorganic Chemistry of the Alkali Metal Ions.

    PubMed

    Kim, Youngsam; Nguyen, Thuy-Tien T; Churchill, David G

    2016-01-01

    The common Group 1 alkali metals are indeed ubiquitous on earth, in the oceans and in biological systems. In this introductory chapter, concepts involving aqueous chemistry and aspects of general coordination chemistry and oxygen atom donor chemistry are introduced. Also, there are nuclear isotopes of importance. A general discussion of Group 1 begins from the prevalence of the ions, and from a comparison of their ionic radii and ionization energies. While oxygen and water molecule binding have the most relevance to biology and in forming a detailed understanding between the elements, there is a wide range of basic chemistry that is potentially important, especially with respect to biological chelation and synthetic multi-dentate ligand design. The elements are widely distributed in life forms, in the terrestrial environment and in the oceans. The details about the workings in animal, as well as plant life are presented in this volume. Important biometallic aspects of human health and medicine are introduced as well. Seeing as the elements are widely present in biology, various particular endogenous molecules and enzymatic systems can be studied. Sodium and potassium are by far the most important and central elements for consideration. Aspects of lithium, rubidium, cesium and francium chemistry are also included; they help in making important comparisons related to the coordination chemistry of Na(+) and K(+). Physical methods are also introduced. PMID:26860297

  17. Sequence-selective metal ion binding to DNA oligonucleotides.

    PubMed

    Frøystein, N A; Davis, J T; Reid, B R; Sletten, E

    1993-07-01

    Metal ion titrations of several DNA oligonucleotides, 10 dodecamers and one decamer have been monitored by 1H NMR spectroscopy in order to elucidate metal ion binding patterns. Also, the effects of paramagnetic impurities on resonance linewidths and NOESY cross-peak intensities have been reversed by EDTA back-titration experiments. 1H 1D NMR spectra were recorded after successive additions of aliquots of different metal salts to oligonucleotide samples. Paramagnetic manganese(II) salts were used in most cases, but a few samples were also titrated with diamagnetic zinc(II). From this study, we conclude that there exists a sequence-selective metal ion binding pattern. The metal ions bind predominantly to 5'-G in the contexts 5'-GC and 5'-GA. The order of preference seems to be GG > or = GA > GT > > GC. No evidence of metal ion binding to 5'-G in 5'-GC steps or to non-G residues was found. The H6 or H8 resonances on preceding (5'-) bases were affected by the adjacent bound paramagnetic metal ion, but no effect was observed on the protons of the succeeding (3'-) base. The metal binding site in the duplexes is most likely at G-N7, as manifested by the pronounced paramagnetic line broadening or diamagnetic shift of the G-H8 signal. This sequence selectivity may be qualitatively explained by a sequence-dependent variation in the molecular electrostatic potentials of guanine residues (MEPs) along the oligonucleotide chain. PMID:8363924

  18. Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems

    PubMed Central

    2014-01-01

    Background The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems. Methods In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr. Results Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs. Conclusions When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system. PMID:24472283

  19. Metal-organic frameworks for lithium ion batteries and supercapacitors

    SciTech Connect

    Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang

    2015-03-15

    Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100–1000 m{sup 2} g{sup −1}) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m{sup 2} g{sup −1}), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefit from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs. - Graphical abstract: MOFs with large surface area and high porosity can offer more reaction sites and charge carriers diffusion path. Thus MOFs are used as cathode, anode, electrolyte, matrix and precursor materials for lithium ion battery, and also as electrode and precursor materials for supercapacitors. - Highlights: • MOFs have potential in electrochemical area due to their high porosity and diversity. • We summarized and compared works on MOFs for lithium ion battery and supercapacitor. • We pointed out critical challenges and provided possible solutions for future study.

  20. Comparative study of ion conducting pathways in borate glasses

    SciTech Connect

    Hall, Andreas; Swenson, Jan; Adams, Stefan

    2006-11-01

    The conduction pathways in metal-halide doped silver, lithium, and sodium diborate glasses have been examined by bond valence analysis of reverse Monte Carlo (RMC) produced structural models of the glasses. Although all glass compositions have basically the same short-range structure of the boron-oxygen network, it is evident that the intermediate-range structure is strongly dependent on the type of mobile ion. The topography of the pathways and the coordination of the pathway sites differ distinctly between the three glass systems. The mobile silver ions in the AgI-doped glass tend to be mainly iodine-coordinated and travel in homogeneously distributed pathways located in salt-rich channels of the borate network. In the NaCl-doped glass, there is an inhomogeneous spatial distribution of pathways that reflects the inhomogeneous introduction of salt ions into the glass. However, since the salt clusters are not connected, no long-range conduction pathways are formed without including also oxygen-rich regions. The pathways in the LiCl-doped glass are slightly more evenly distributed compared to the NaCl-doped glass (but not as ordered as in the AgI-doped glass), and the regions of mainly oxygen-coordinated pathway sites are of higher importance for the long-range migration. In order to more accurately investigate how these differences in the intermediate-range order of the glasses affect the ionic conductivity, we have compared the realistic structure models to more or less randomized structures. An important conclusion from this comparison is that we find no evidence that a pronounced intermediate-range order in the atomic structure or in the network of conduction pathways, as in the AgI-doped glass, is beneficial for the dc conductivity.

  1. Progress in metal ion separation and preconcentration : an overview.

    SciTech Connect

    Bond, A. H.

    1998-05-19

    A brief historical perspective covering the most mature chemically-based metal ion separation methods is presented, as is a summary of the recommendations made in the 1987 National Research Council (NRC) report entitled ''Separation and Purification: Critical Needs and Opportunities''. A review of Progress in Metal Ion Separation and Preconcentration shows that advances are occurring in each area of need cited by the NRC. Following an explanation of the objectives and general organization of this book, the contents of each chapter are briefly summarized and some future research opportunities in metal ion separations are presented.

  2. Separation of platinum group metal ions by Donnan dialysis

    SciTech Connect

    Brajter, K.; Slonawska, K.; Cox, J.A.

    1985-10-01

    Separations of metal ions on the basis of Donnan dialysis across anion-exchange membranes should be possible if the receiver electrolyte composition favors the formation of selected anionic complexes of the sample metal ions. Moreover, such a separation has the possibility of being better suited from some applications than batch or column experiments with anion-exchange resins. The above hypothesis are tested on the platinum-group metal ions, Pt(IV), Rh(III), Pd(II), Ir(III), and Ir(IV). 13 references, 4 tables.

  3. An Animal Model Using Metallic Ions to Produce Autoimmune Nephritis.

    PubMed

    Ramírez-Sandoval, Roxana; Luévano-Rodríguez, Nayeli; Rodríguez-Rodríguez, Mayra; Pérez-Pérez, María Elena; Saldívar-Elias, Sergio; Gurrola-Carlos, Reinaldo; Avalos-Díaz, Esperanza; Bollain-y-Goytia, Juan José; Herrera-Esparza, Rafael

    2015-01-01

    Autoimmune nephritis triggered by metallic ions was assessed in a Long-Evans rat model. The parameters evaluated included antinuclear autoantibody production, kidney damage mediated by immune complexes detected by immunofluorescence, and renal function tested by retention of nitrogen waste products and proteinuria. To accomplish our goal, the animals were treated with the following ionic metals: HgCl2, CuSO4, AgNO3, and Pb(NO3)2. A group without ionic metals was used as the control. The results of the present investigation demonstrated that metallic ions triggered antinuclear antibody production in 60% of animals, some of them with anti-DNA specificity. Furthermore, all animals treated with heavy metals developed toxic glomerulonephritis with immune complex deposition along the mesangium and membranes. These phenomena were accompanied by proteinuria and increased concentrations of urea. Based on these results, we conclude that metallic ions may induce experimental autoimmune nephritis. PMID:26064998

  4. An Animal Model Using Metallic Ions to Produce Autoimmune Nephritis

    PubMed Central

    Ramírez-Sandoval, Roxana; Luévano-Rodríguez, Nayeli; Rodríguez-Rodríguez, Mayra; Pérez-Pérez, María Elena; Saldívar-Elias, Sergio; Gurrola-Carlos, Reinaldo; Avalos-Díaz, Esperanza; Bollain-y-Goytia, Juan José

    2015-01-01

    Autoimmune nephritis triggered by metallic ions was assessed in a Long-Evans rat model. The parameters evaluated included antinuclear autoantibody production, kidney damage mediated by immune complexes detected by immunofluorescence, and renal function tested by retention of nitrogen waste products and proteinuria. To accomplish our goal, the animals were treated with the following ionic metals: HgCl2, CuSO4, AgNO3, and Pb(NO3)2. A group without ionic metals was used as the control. The results of the present investigation demonstrated that metallic ions triggered antinuclear antibody production in 60% of animals, some of them with anti-DNA specificity. Furthermore, all animals treated with heavy metals developed toxic glomerulonephritis with immune complex deposition along the mesangium and membranes. These phenomena were accompanied by proteinuria and increased concentrations of urea. Based on these results, we conclude that metallic ions may induce experimental autoimmune nephritis. PMID:26064998

  5. Blood metal ion testing is an effective screening tool to identify poorly performing metal-on-metal bearing surfaces

    PubMed Central

    Sidaginamale, R. P.; Joyce, T. J.; Lord, J. K.; Jefferson, R.; Blain, P. G.; Nargol, A. V. F.; Langton, D. J.

    2013-01-01

    Objectives The aims of this piece of work were to: 1) record the background concentrations of blood chromium (Cr) and cobalt (Co) concentrations in a large group of subjects; 2) to compare blood/serum Cr and Co concentrations with retrieved metal-on-metal (MoM) hip resurfacings; 3) to examine the distribution of Co and Cr in the serum and whole blood of patients with MoM hip arthroplasties; and 4) to further understand the partitioning of metal ions between the serum and whole blood fractions. Methods A total of 3042 blood samples donated to the local transfusion centre were analysed to record Co and Cr concentrations. Also, 91 hip resurfacing devices from patients who had given pre-revision blood/serum samples for metal ion analysis underwent volumetric wear assessment using a coordinate measuring machine. Linear regression analysis was carried out and receiver operating characteristic curves were constructed to assess the reliability of metal ions to identify abnormally wearing implants. The relationship between serum and whole blood concentrations of Cr and Co in 1048 patients was analysed using Bland-Altman charts. This relationship was further investigated in an in vitro study during which human blood was spiked with trivalent and hexavalent Cr, the serum then separated and the fractions analysed. Results Only one patient in the transfusion group was found to have a blood Co > 2 µg/l. Blood/Serum Cr and Co concentrations were reliable indicators of abnormal wear. Blood Co appeared to be the most useful clinical test, with a concentration of 4.5 µg/l showing sensitivity and specificity for the detection of abnormal wear of 94% and 95%, respectively. Generated metal ions tended to fill the serum compartment preferentially in vivo and this was replicated in the in vitro study when blood was spiked with trivalent Cr and bivalent Co. Conclusions Blood/serum metal ion concentrations are reliable indicators of abnormal wear processes. Important differences exist

  6. Rechargeable dual-metal-ion batteries for advanced energy storage.

    PubMed

    Yao, Hu-Rong; You, Ya; Yin, Ya-Xia; Wan, Li-Jun; Guo, Yu-Guo

    2016-04-14

    Energy storage devices are more important today than any time before in human history due to the increasing demand for clean and sustainable energy. Rechargeable batteries are emerging as the most efficient energy storage technology for a wide range of portable devices, grids and electronic vehicles. Future generations of batteries are required to have high gravimetric and volumetric energy, high power density, low price, long cycle life, high safety and low self-discharge properties. However, it is quite challenging to achieve the above properties simultaneously in state-of-the-art single metal ion batteries (e.g. Li-ion batteries, Na-ion batteries and Mg-ion batteries). In this contribution, hybrid-ion batteries in which various metal ions simultaneously engage to store energy are shown to provide a new perspective towards advanced energy storage: by connecting the respective advantages of different metal ion batteries they have recently attracted widespread attention due to their novel performances. The properties of hybrid-ion batteries are not simply the superposition of the performances of single ion batteries. To enable a distinct description, we only focus on dual-metal-ion batteries in this article, for which the design and the benefits are briefly discussed. We enumerate some new results about dual-metal-ion batteries and demonstrate the mechanism for improving performance based on knowledge from the literature and experiments. Although the search for hybrid-ion batteries is still at an early age, we believe that this strategy would be an excellent choice for breaking the inherent disadvantages of single ion batteries in the near future. PMID:26996438

  7. Metal ion levels: how can they help us?

    PubMed

    Griffin, William L

    2014-04-01

    Ion levels have been shown to reliably predict abnormal function of the bearing surface with increased wear, but ion levels should not be used alone as a trigger for when to proceed with revision surgery with metal-metal articulations. Risk stratification strategies help determine which patients should be monitored more closely with serial ion levels, cross-sectional imaging with a MARS MRI, or proceed on to revision. Based on the current data available, an ion level greater than 4.5 ppb (Cr or Co) may serve as a threshold for when abnormal wear is occurring, and is suggested as a trigger for a MARS MRI scan. PMID:24655610

  8. Extracting metal ions with diphosphonic acid, or derivative thereof

    DOEpatents

    Horwitz, Earl P.; Gatrone, Ralph C.; Nash, Kenneth L.

    1994-01-01

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described.

  9. Extracting metal ions with diphosphonic acid, or derivative thereof

    DOEpatents

    Horwitz, E.P.; Gatrone, R.C.; Nash, K.L.

    1994-07-26

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulfur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described. 1 fig.

  10. Metallic glass as a temperature sensor during ion plating

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    The temperature of the interface and/or a superficial layer of a substrate during ion plating was investigated using a metallic glass of the composition Fe67Co18B14Si1 as the substrate and as the temperature sensor. Transmission electron microscopy and diffraction studies determined the microstructure of the ion-plated gold film and the substrate. Results indicate that crystallization occurs not only in the film, but also in the substrate. The grain size of crystals formed during ion plating was 6 to 60 nm in the gold film and 8 to 100 nm in the substrate at a depth of 10 to 15 micrometers from the ion-plated interface. The temperature rise of the substrate during ion plating was approximately 500 C. Discontinuous changes in metallurgical microstructure, and physical, chemical, and mechanical properties during the amorphous to crystalline transition in metallic glasses make metallic glasses extremely useful materials for temperature sensor applications in coating processes.

  11. Metallic glass as a temperature sensor during ion plating

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1984-01-01

    The temperature of the interface and/or a superficial layer of a substrate during ion plating was investigated using a metallic glass of the composition Fe67Co18B14Si1 as the substrate and as the temperature sensor. Transmission electron microscopy and diffraction studies determined the microstructure of the ion-plated gold film and the substrate. Results indicate that crystallization occurs not only in the film, but also in the substrate. The grain size of crystals formed during ion plating was 6 to 60 nm in the gold film and 8 to 100 nm in the substrate at a depth of 10 to 15 micrometers from the ion-plated interface. The temperature rise of the substrate during ion plating was approximately 500 C. Discontinuous changes in metallurgical microstructure, and physical, chemical, and mechanical properties during the amorphous to crystalline transition in metallic glasses make metallic glasses extremely useful materials for temperature sensor applications in coating processes.

  12. Predicting the relative toxicity of metal ions using ion characteristics: Microtox{reg_sign} bioluminescence assay

    SciTech Connect

    McCloskey, J.T.; Newman, M.C.; Clark, S.B.

    1996-10-01

    Quantitative structure-activity relationships have been used to predict the relative toxicity of organic compounds. Although not as common, ion characteristics have also proven useful for predicting the relative toxicity of metal ions. The purpose of this study was to determine if the relative toxicity of metal ions using the Microtox{reg_sign} bioassay was predictable using ion characteristics. Median effect concentrations (EC50s) were determined for 20 metals in a NaNO{sub 3} medium, which reflected freshwater speciation conditions, using the Microtox bacterial assay. The log of EC50 values was modeled using several ion characteristics, and Akaike`s Information Criterion was calculated to determine which ion characteristics provided the best fit. Whether modeling total ion or free ion EC50 values, the one variable which best modeled EC50s was the softness index, while a combination of {chi}{sub m}{sup 2}r ({chi}{sub m} = electronegativity, r = Pauling ionic radius) and {vert_bar}log K{sub OH}{vert_bar} was the best two-variable model. Other variables, including {Delta}E{sub 0} and {chi}{sub m}{sup 2}r (one-variable models) and (AN/{Delta}IP, {Delta}E{sub 0}) and ({chi}{sub m}{sup 2}r, Z{sup 2}/r) (two-variable models), also gave adequate fits. Modeling with speciated (free ion) versus unspeciated (total ion) EC50 values did not improve fits. Modeling mono-, di-, and trivalent metal ions separately improved the models. The authors conclude that ion characteristics can be used to predict the relative toxicity of metal ions whether in freshwater (NaNO{sub 3} medium) or saltwater (NaCl medium) speciation conditions and that this approach can be applied to metal ions varying widely in both valence and binding tendencies.

  13. An Engineered Palette of Metal Ion Quenchable Fluorescent Proteins

    PubMed Central

    Yu, Xiaozhen; Strub, Marie-Paule; Barnard, Travis J.; Noinaj, Nicholas; Piszczek, Grzegorz; Buchanan, Susan K.; Taraska, Justin W.

    2014-01-01

    Many fluorescent proteins have been created to act as genetically encoded biosensors. With these sensors, changes in fluorescence report on chemical states in living cells. Transition metal ions such as copper, nickel, and zinc are crucial in many physiological and pathophysiological pathways. Here, we engineered a spectral series of optimized transition metal ion-binding fluorescent proteins that respond to metals with large changes in fluorescence intensity. These proteins can act as metal biosensors or imaging probes whose fluorescence can be tuned by metals. Each protein is uniquely modulated by four different metals (Cu2+, Ni2+, Co2+, and Zn2+). Crystallography revealed the geometry and location of metal binding to the engineered sites. When attached to the extracellular terminal of a membrane protein VAMP2, dimeric pairs of the sensors could be used in cells as ratiometric probes for transition metal ions. Thus, these engineered fluorescent proteins act as sensitive transition metal ion-responsive genetically encoded probes that span the visible spectrum. PMID:24752441

  14. Prostate cancer outcome and tissue levels of metal ions

    USGS Publications Warehouse

    Sarafanov, A.G.; Todorov, T.I.; Centeno, J.A.; MacIas, V.; Gao, W.; Liang, W.-M.; Beam, C.; Gray, Michael A.; Kajdacsy-Balla, A.

    2011-01-01

    BACKGROUND There are several studies examining prostate cancer and exposure to cadmium, iron, selenium, and zinc. Less data are available on the possible influence of these metal ions on prostate cancer outcome. This study measured levels of these ions in prostatectomy samples in order to examine possible associations between metal concentrations and disease outcome. METHODS We obtained formalin fixed paraffin embedded tissue blocks of prostatectomy samples of 40 patients with PSA recurrence, matched 1:1 (for year of surgery, race, age, Gleason grading, and pathology TNM classification) with tissue blocks from 40 patients without recurrence (n = 80). Case-control pairs were compared for the levels of metals in areas adjacent to tumors. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for quantification of Cd, Fe, Zn, and Se. RESULTS Patients with biochemical (PSA) recurrence of disease had 12% lower median iron (95 ??g/g vs. 111 ??g/g; P = 0.04) and 21% lower zinc (279 ??g/g vs. 346 ??g/g; P = 0.04) concentrations in the normal-appearing tissue immediately adjacent to cancer areas. Differences in cadmium (0.489 ??g/g vs. 0.439 ??g/g; 4% higher) and selenium (1.68 ??g/g vs. 1.58 ??g/g; 5% higher) levels were not statistically significant in recurrence cases, when compared to non-recurrences (P = 0.40 and 0.21, respectively). CONCLUSIONS There is an association between low zinc and low iron prostate tissue levels and biochemical recurrence in prostate cancer. Whether these novel findings are a cause or effect of more aggressive tumors, or whether low zinc and iron prostatic levels raise implications for therapy, remains to be investigated. Copyright ?? 2011 Wiley-Liss, Inc.

  15. Smart textile device using ion polymer metal compound.

    PubMed

    Nakamura, Taro; Ihara, Tadashi

    2013-01-01

    We have developed a smart textile device that detects angular displacement of attached surface using ion polymer metal compound. The device was composed of ion polymer metal compound (IPMC) which was fabricated from Nafion resin by heat-press and chemical gold plating. The generated voltage from IPMC was measured as a function of bending angle. Fabricated IPMC device was weaved into a cotton cloth and multidirectional movements were detected. PMID:24109750

  16. An optical dosimeter for monitoring heavy metal ions in water

    NASA Astrophysics Data System (ADS)

    Mignani, Anna G.; Regan, Fiona; Leamy, D.; Mencaglia, A. A.; Ciaccheri, L.

    2005-05-01

    This work presents an optochemical dosimeter for determining and discriminating nickel, copper, and cobalt ions in water that can be used as an early warning system for water pollution. An inexpensive fiber optic spectrophotometer monitors the sensor's spectral behavior under exposure to water solutions of heavy metal ions in the 1-10 mg/l concentration range. The Principal Component Analysis (PCA) method quantitatively determines the heavy metals and discriminates their type and combination.

  17. Metal ion implantation for large scale surface modification

    SciTech Connect

    Brown, I.G.

    1992-10-01

    Intense energetic beams of metal ions can be produced by using a metal vapor vacuum arc as the plasma discharge from which the ion beam is formed. We have developed a number of ion sources of this kind and have built a metal ion implantation facility which can produce repetitively pulsed ion beams with mean ion energy up to several hundred key, pulsed beam current of more than an ampere, and time averaged current of several tens of milliamperes delivered onto a downstream target. We've also done some preliminary work on scaling up this technology to very large size. For example, a 50-cm diameter (2000 cm[sup 2]) set of beam formation electrodes was used to produce a pulsed titanium beam with ion current over 7 amperes at a mean ion energy of 100 key. Separately, a dc embodiment has been used to produce a dc titanium ion beam with current over 600 mA, power supply limited in this work, and up to 6 amperes of dc plasma ion current was maintained for over an hour. In a related program we've developed a plasma immersion method for applying thin metallic and compound films in which the added species is atomically mixed to the substrate. By adding a gas flow to the process, well-bonded compound films can also be formed; metallic films and multilayers as well as oxides and nitrides with mixed transition zones some hundreds of angstroms thick have been synthesized. Here we outline these parallel metal-plasma-based research programs and describe the hardware that we've developed and some of the surface modification research that we've done with it.

  18. Production of negative hydrogen ions on metal grids

    SciTech Connect

    Oohara, W.; Maetani, Y.; Takeda, Takashi; Takeda, Toshiaki; Yokoyama, H.; Kawata, K.

    2015-03-15

    Negative hydrogen ions are produced on a nickel grid with positive-ion irradiation. In order to investigate the production mechanism, a copper grid without the chemisorption of hydrogen atoms and positive helium ions without negative ionization are used for comparison. Positive hydrogen ions reflected on the metal surface obtain two electrons from the surface and become negatively ionized. It is found that the production yield of negative ions by desorption ionization of chemisorbed hydrogen atoms seems to be small, and the production is a minor mechanism.

  19. Comparative Metal Oxide Nanoparticle Toxicity Using Embryonic Zebrafish

    PubMed Central

    Wehmas, Leah C.; Anders, Catherine; Chess, Jordan; Punnoose, Alex; Pereira, Cliff B.; Greenwood, Juliet A.; Tanguay, Robert L.

    2015-01-01

    Engineered metal oxide nanoparticles (MO NPs) are finding increasing utility in the medical field as anticancer agents. Before validation of in vivo anticancer efficacy can occur, a better understanding of whole-animal toxicity is required. We compared the toxicity of seven widely used semiconductor MO NPs made from zinc oxide (ZnO), titanium dioxide, cerium dioxide and tin dioxide prepared in pure water and in synthetic seawater using a five-day embryonic zebrafish assay. We hypothesized that the toxicity of these engineered MO NPs would depend on physicochemical properties. Significant agglomeration of MO NPs in aqueous solutions is common making it challenging to associate NP characteristics such as size and charge with toxicity. However, data from our agglomerated MO NPs suggests that the elemental composition and dissolution potential are major drivers of toxicity. Only ZnO caused significant adverse effects of all MO particles tested, and only when prepared in pure water (point estimate median lethal concentration = 3.5–9.1 mg/L). This toxicity was life stage dependent. The 24 h toxicity increased greatly (~22.7 fold) when zebrafish exposures started at the larval life stage compared to the 24 hour toxicity following embryonic exposure. Investigation into whether dissolution could account for ZnO toxicity revealed high levels of zinc ion (40–89% of total sample) were generated. Exposure to zinc ion equivalents revealed dissolved Zn2+ may be a major contributor to ZnO toxicity. PMID:26029632

  20. Functional Identification of Catalytic Metal Ion Binding Sites within RNA

    PubMed Central

    2005-01-01

    The viability of living systems depends inextricably on enzymes that catalyze phosphoryl transfer reactions. For many enzymes in this class, including several ribozymes, divalent metal ions serve as obligate cofactors. Understanding how metal ions mediate catalysis requires elucidation of metal ion interactions with both the enzyme and the substrate(s). In the Tetrahymena group I intron, previous work using atomic mutagenesis and quantitative analysis of metal ion rescue behavior identified three metal ions (MA, MB, and MC) that make five interactions with the ribozyme substrates in the reaction's transition state. Here, we combine substrate atomic mutagenesis with site-specific phosphorothioate substitutions in the ribozyme backbone to develop a powerful, general strategy for defining the ligands of catalytic metal ions within RNA. In applying this strategy to the Tetrahymena group I intron, we have identified the pro-SP phosphoryl oxygen at nucleotide C262 as a ribozyme ligand for MC. Our findings establish a direct connection between the ribozyme core and the functionally defined model of the chemical transition state, thereby extending the known set of transition-state interactions and providing information critical for the application of the recent group I intron crystallographic structures to the understanding of catalysis. PMID:16092891

  1. Implantation of nitrogen, carbon, and phosphorus ions into metals

    SciTech Connect

    Guseva, M.I.; Gordeeva, G.V.

    1987-01-01

    The application of ion implantation for alloying offers a unique opportunity to modify the chemical composition, phase constitution, and microstructure of the surface layers of metals. The authors studied ion implantation of nitrogen and carbon into the surface layers of metallic targets. The phase composition of the implanted layers obtained on the Kh18N10T stainless steel, the refractory molybdenum alloy TsM-6, niobium, and nickel was determined according to the conventional method of recording the x-ray diffraction pattern of the specimens using monochromatic FeK/sub alpha/-radiation on a DRON-2,0 diffractometer. The targets were bombarded at room temperature in an ILU-3 ion accelerator. The implantation of metalloid ions was also conducted with the targets being bombarded with 100-keV phosphorus ions and 40-keV carbon ions.

  2. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

    The low-frequency electrostatic waves in metallic nanowires are studied using the quantum hydrodynamic model, in which the electron and ion components of the system are regarded as a two-species quantum plasma system. The Poisson equation as well as appropriate quantum boundary conditions give the analytical expressions of dispersion relations of the surface and bulk quantum ion-acoustic wave oscillations.

  3. CMOS-compatible metal-stabilized nanostructured Si as anodes for lithium-ion microbatteries

    NASA Astrophysics Data System (ADS)

    Lee, Gibaek; Schweizer, Stefan L.; Wehrspohn, Ralf B.

    2014-11-01

    The properties of fully complementary metal-oxide semiconductor (CMOS)-compatible metal-coated nanostructured silicon anodes for Li-ion microbatteries have been studied. The one-dimensional nanowires on black silicon (nb-Si) were prepared by inductively coupled plasma (ICP) etching and the metal (Au and Cu) coatings by successive magnetron sputtering technique. The Cu-coated nb-Si show the most promising electrochemical performance enhancements for the initial specific capacity as well as their cyclability compared to pristine nb-Si. The electrochemical and microstructural properties before and after cycling of the metal-coated nb-Si compared to their pristine counterparts are discussed in detail.

  4. Structural Metals in the Group I Intron: A Ribozyme with a Multiple Metal Ion Core

    SciTech Connect

    Stahley,M.; Adams, P.; Wang, J.; Strobel, S.

    2007-01-01

    Metal ions play key roles in the folding and function for many structured RNAs, including group I introns. We determined the X-ray crystal structure of the Azoarcus bacterial group I intron in complex with its 5' and 3' exons. In addition to 222 nucleotides of RNA, the model includes 18 Mg2+ and K+ ions. Five of the metals bind within 12 Angstroms of the scissile phosphate and coordinate the majority of the oxygen atoms biochemically implicated in conserved metal-RNA interactions. The metals are buried deep within the structure and form a multiple metal ion core that is critical to group I intron structure and function. Eight metal ions bind in other conserved regions of the intron structure, and the remaining five interact with peripheral structural elements. Each of the 18 metals mediates tertiary interactions, facilitates local bends in the sugar-phosphate backbone or binds in the major groove of helices. The group I intron has a rich history of biochemical efforts aimed to identify RNA-metal ion interactions. The structural data are correlated to the biochemical results to further understand the role of metal ions in group I intron structure and function.

  5. Plasma spectroscopy of metal ions for hyper-electron cyclotron resonance ion source.

    PubMed

    Muto, Hideshi; Ohshiro, Yukimitsu; Yamaka, Shoichi; Watanabe, Shin-ichi; Oyaizu, Michihiro; Kubono, Shigeru; Yamaguchi, Hidetoshi; Kase, Masayuki; Hattori, Toshiyuki; Shimoura, Susumu

    2014-02-01

    In this research, the optical line spectra of metal ions from ECR plasma were observed using a grating monochromator with a photomultiplier. The light intensity of line spectrum from the ECR plasma had a strong correlation with ion beam intensity measured by a magnetic mass analyzer. This correlation is a significant information for the beam tuning process, because it allows to conduct the extraction of the desired metal ion species from the ECR plasma. Separation of ion species of the same charge to mass ratio with an electromagnetic mass analyzer is known to be an exceptionally complex process, but this research provides a new approach for its simplification. In this paper the grating monochromator method for metal ion beam tuning such as (40)Ca(12+), (56)Fe(15+), and (85)Rb(20+) of hyper-ECR ion source as an injector for RIKEN Azimuthal Varying Field cyclotron is described. PMID:24593484

  6. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1990-03-20

    This patent describes a method of removing heavy metals from aqueous solution, a composition of matter used in effecting the removal, and apparatus used in effecting the removal. One or more of the polypeptides, poly ({gamma}-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ({gamma}-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  7. Removal of metal ions from aqueous solution

    DOEpatents

    Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

    1990-01-01

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  8. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1988-08-26

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly ({gamma}-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ({gamma}-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  9. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

    1990-11-13

    A method is disclosed of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly ([gamma]glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ([gamma]glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form. 1 fig.

  10. Removal of metal ions from aqueous solution

    SciTech Connect

    Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

    1990-11-13

    A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heayv metals from solution. This also results in the removal of the metals from the column in a concentrated form.

  11. In Vivo Metal Ion Imaging Using Fluorescent Sensors.

    PubMed

    Van de Bittner, Genevieve C; Hirayama, Tasuku

    2016-01-01

    In vivo imaging in living animals provides the ability to monitor alterations of signaling molecules, ions, and other biological components during various life stages and in disease. The data gained from in vivo imaging can be used for biological discovery or to determine elements of disease progression and can inform the development and translation of therapeutics. Herein, we present theories behind small-molecule, fluorescent, metal ion sensors as well as the methods for their successful application to in vivo metal ion imaging, including ex vivo validation. PMID:27283424

  12. A comprehensive platform to investigate protein-metal ion interactions by affinity capillary electrophoresis.

    PubMed

    Alhazmi, Hassan A; Nachbar, Markus; Albishri, Hassan M; Abd El-Hady, Deia; Redweik, Sabine; El Deeb, Sami; Wätzig, Hermann

    2015-03-25

    In this work, the behavior of several metal ions with different globular proteins was investigated by affinity capillary electrophoresis. Screening was conducted by applying a proper rinsing protocol developed by our group. The use of 0.1M EDTA in the rinsing solution successfully desorbs metal ions from the capillary wall. The mobility ratio was used to evaluate the precision of the method. Excellent precision for repeated runs was achieved for different protein metal ion interactions (RSD% of 0.05-1.0%). Run times were less than 6 min for all of the investigated interactions. The method has been successfully applied for the interaction study of Li(+), Na(+), Mg(2+), Ca(2+), Ba(2+), Al(3+), Ga(3+), La(3+), Pd(2+), Ir(3+), Ru(3+), Rh(3+), Pt(2+), Pt(4+), Os(3+), Au(3+), Au(+), Ag(+), Cu(1+), Cu(2+), Fe(2+), Fe(3+), Co(2+), Ni(2+), Cr(3+), V(3+), MoO4(2-) and SeO3(2-) with bovine serum albumin, ovalbumin, β-lactoglobulin and myoglobin. Different interaction values were obtained for most of the tested metal ions even for that in the same metal group. Results were discussed and compared in view of metal and semimetal group's interaction behavior with the tested proteins. The calculated normalized difference of mobility ratios for each protein-metal ion interaction and its sign (positive and negative) has been successfully used to detect the interaction and estimate further coordination of the bound metal ion, respectively. The comprehensive platform summarizes all the obtained interaction results, and is valuable for any future protein-metal ion investigation. PMID:25638307

  13. Surface modification by metal ion implantation forming metallic nanoparticles in an insulating matrix

    NASA Astrophysics Data System (ADS)

    Salvadori, M. C.; Teixeira, F. S.; Sgubin, L. G.; Cattani, M.; Brown, I. G.

    2014-08-01

    There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in the insulating matrix. These nanocomposites have been characterized by measuring the resistivity of the composite layer as a function of the implantation dose. The experimental results are compared with a model based on percolation theory, in which electron transport through the composite is explained by conduction through a random resistor network formed by the metallic nanoparticles. Excellent agreement is found between the experimental results and the predictions of the theory. We conclude in that the conductivity process is due only to percolation (when the conducting elements are in geometric contact) and that the contribution from tunneling conduction is negligible.

  14. Neutralization by Metal Ions of the Toxicity of Sodium Selenide

    PubMed Central

    Dauplais, Marc; Lazard, Myriam; Blanquet, Sylvain; Plateau, Pierre

    2013-01-01

    Inert metal-selenide colloids are found in animals. They are believed to afford cross-protection against the toxicities of both metals and selenocompounds. Here, the toxicities of metal salt and sodium selenide mixtures were systematically studied using the death rate of Saccharomyces cerevisiae cells as an indicator. In parallel, the abilities of these mixtures to produce colloids were assessed. Studied metal cations could be classified in three groups: (i) metal ions that protect cells against selenium toxicity and form insoluble colloids with selenide (Ag+, Cd2+, Cu2+, Hg2+, Pb2+ and Zn2+), (ii) metal ions which protect cells by producing insoluble metal-selenide complexes and by catalyzing hydrogen selenide oxidation in the presence of dioxygen (Co2+ and Ni2+) and, finally, (iii) metal ions which do not afford protection and do not interact (Ca2+, Mg2+, Mn2+) or weakly interact (Fe2+) with selenide under the assayed conditions. When occurring, the insoluble complexes formed from divalent metal ions and selenide contained equimolar amounts of metal and selenium atoms. With the monovalent silver ion, the complex contained two silver atoms per selenium atom. Next, because selenides are compounds prone to oxidation, the stabilities of the above colloids were evaluated under oxidizing conditions. 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), the reduction of which can be optically followed, was used to promote selenide oxidation. Complexes with cadmium, copper, lead, mercury or silver resisted dissolution by DTNB treatment over several hours. With nickel and cobalt, partial oxidation by DTNB occurred. On the other hand, when starting from ZnSe or FeSe complexes, full decompositions were obtained within a few tens of minutes. The above properties possibly explain why ZnSe and FeSe nanoparticles were not detected in animals exposed to selenocompounds. PMID:23342137

  15. Metal ion implantation in inert polymers for strain gauge applications

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Giovanni; Massaro, Marcello; Piscopiello, Emanuela; Tapfer, Leander

    2010-10-01

    Metal ion implantation in inert polymers may produce ultra-thin conducting films below the polymer surface. These subsurface films are promising structures for strain gauge applications. To this purpose, polycarbonate substrates were irradiated at room temperature with low-energy metal ions (Cu + and Ni +) and with fluences in the range between 1 × 10 16 and 1 × 10 17 ions/cm 2, in order to promote the precipitation of dispersed metal nanoparticles or the formation of a continuous thin film. The nanoparticle morphology and the microstructural properties of polymer nanocomposites were investigated by glancing-incidence X-ray diffraction and transmission electron microscopy (TEM) measurements. At lower fluences (<5 × 10 16 ions/cm 2) a spontaneous precipitation of spherical-shaped metal nanoparticles occurred below the polymer top-surface (˜50 nm), whereas at higher fluences the aggregation of metal nanoparticles produced the formation of a continuous polycrystalline nanofilm. Furthermore, a characteristic surface plasmon resonance peak was observed for nanocomposites produced at lower ion fluences, due to the presence of Cu nanoparticles. A reduced electrical resistance of the near-surface metal-polymer nanocomposite was measured. The variation of electrical conductivity as a function of the applied surface load was measured: we found a linear relationship and a very small hysteresis.

  16. The use of divalent metal ions by type II topoisomerases.

    PubMed

    Deweese, Joseph E; Osheroff, Neil

    2010-07-01

    Type II topoisomerases are essential enzymes that regulate DNA under- and overwinding and remove knots and tangles from the genetic material. In order to carry out their critical physiological functions, these enzymes utilize a double-stranded DNA passage mechanism that requires them to generate a transient double-stranded break. Consequently, while necessary for cell survival, type II topoisomerases also have the capacity to fragment the genome. This feature of the prokaryotic and eukaryotic enzymes, respectively, is exploited to treat a variety of bacterial infections and cancers in humans. All type II topoisomerases require divalent metal ions for catalytic function. These metal ions function in two separate active sites and are necessary for the ATPase and DNA cleavage/ligation activities of the enzymes. ATPase activity is required for the strand passage process and utilizes the metal-dependent binding and hydrolysis of ATP to drive structural rearrangements in the protein. Both the DNA cleavage and ligation activities of type II topoisomerases require divalent metal ions and appear to utilize a novel variant of the canonical two-metal-ion phosphotransferase/hydrolase mechanism to facilitate these reactions. This article will focus primarily on eukaryotic type II topoisomerases and the roles of metal ions in the catalytic functions of these enzymes. PMID:20703329

  17. The Use of Divalent Metal Ions by Type II Topoisomerases

    PubMed Central

    Deweese, Joseph E.; Osheroff, Neil

    2010-01-01

    Type II topoisomerases are essential enzymes that regulate DNA under- and overwinding and remove knots and tangles from the genetic material. In order to carry out their critical physiological functions, these enzymes utilize a double-stranded DNA passage mechanism that requires them to generate a transient double-stranded break. Consequently, while necessary for cell survival, type II topoisomerases also have the capacity to fragment the genome. This feature of the prokaryotic and eukaryotic enzymes, respectively, is exploited to treat a variety of bacterial infections and cancers in humans. All type II topoisomerases require divalent metal ions for catalytic function. These metal ions function in two separate active sites and are necessary for the ATPase and DNA cleavage/ligation activities of the enzymes. ATPase activity is required for the strand passage process and utilizes the metal-dependent binding and hydrolysis of ATP to drive structural rearrangements in the protein. Both the DNA cleavage and ligation activities of type II topoisomerases require divalent metal ions and appear to utilize a novel variant of the canonical two-metal-ion phosphotransferase/hydrolase mechanism to facilitate these reactions. This article will focus primarily on eukaryotic type II topoisomerases and the roles of metal ions in the catalytic functions of these enzymes. PMID:20703329

  18. Luminometric Label Array for Quantification and Identification of Metal Ions.

    PubMed

    Pihlasalo, Sari; Montoya Perez, Ileana; Hollo, Niklas; Hokkanen, Elina; Pahikkala, Tapio; Härmä, Harri

    2016-05-17

    Quantification and identification of metal ions has gained interest in drinking water and environmental analyses. We have developed a novel label array method for the quantification and identification of metal ions in drinking water. This simple ready-to-go method is based on the nonspecific interactions of multiple unstable lanthanide chelates and nonantenna ligands with sample leading to a luminescence signal profile, unique to the sample components. The limit of detection at ppb concentration level and average coefficient of variation of 10% were achieved with the developed label array. The identification of 15 different metal ions including different oxidation states Cr(3+)/Cr(6+), Cu(+)/Cu(2+), Fe(2+)/Fe(3+), and Pb(2+)/Pb(4+) was demonstrated. Moreover, a binary mixture of Cu(2+) and Fe(3+) and ternary mixture of Cd(2+), Ni(2+), and Pb(2+) were measured and individual ions were distinguished. PMID:27086705

  19. Ion beam induced nanosized Ag metal clusters in glass

    NASA Astrophysics Data System (ADS)

    Mahnke, H.-E.; Schattat, B.; Schubert-Bischoff, P.; Novakovic, N.

    2006-04-01

    Silver metal clusters have been formed in soda lime glass by high-energy heavy-ion irradiation at ISL. The metal cluster formation was detected with X-ray absorption spectroscopy (EXAFS) in fluorescence mode, and the shape of the clusters was imaged with transmission electron microscopy. While annealing in reducing atmosphere alone, leads to the formation of metal clusters in Ag-containing glasses, where the Ag was introduced by ion-exchange, such clusters are not very uniform in size and are randomly distributed over the Ag-containing glass volume. Irradiation with 600-MeV Au ions followed by annealing, however, results in clusters more uniform in size and arranged in chains parallel to the direction of the ion beam.

  20. Hall transport of divalent metal ion modified DNA lattices

    SciTech Connect

    Dugasani, Sreekantha Reddy; Lee, Keun Woo; Yoo, Sanghyun; Gnapareddy, Bramaramba; Bashar, Saima; Park, Sung Ha; Kim, Si Joon; Jung, Joohye; Jung, Tae Soo; Kim, Hyun Jae

    2015-06-29

    We investigate the Hall transport characteristics of double-crossover divalent metal ion (Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+})-modified DNA (M-DNA) lattices grown on silica via substrate-assisted growth. The electronic characteristics of the M-DNA lattices are investigated by varying the concentration of the metal ions and then conducting Hall measurements, including resistivity, Hall mobility, carrier concentration, and magneto resistance. The tendency of the resistivity and Hall mobility was to initially decrease as the ion concentration increased, until reaching the saturation concentration (C{sub s}) of each metal ion, and then to increase as the ion concentration increased further. On the other hand, the carrier concentration revealed the opposite tendency as the resistivity and Hall mobility. The specific binding (≤C{sub s}) and the nonspecific aggregates (>C{sub s}) of the ions into the DNA lattices were significantly affected by the Hall characteristics. The numerical ranges of the Hall parameters revealed that the M-DNA lattices with metal ions had semiconductor-like characteristics. Consequently, the distinct characteristics of the electrical transport through M-DNA lattices will provide useful information on the practical use of such structures in physical devices and chemical sensors.

  1. Means for obtaining a metal ion beam from a heavy-ion cyclotron source

    DOEpatents

    Hudson, E.D.; Mallory, M.L.

    1975-08-01

    A description is given of a modification to a cyclotron ion source used in producing a high intensity metal ion beam. A small amount of an inert support gas maintains the usual plasma arc, except that it is necessary for the support gas to have a heavy mass, e.g., xenon or krypton as opposed to neon. A plate, fabricated from the metal (or anything that can be sputtered) to be ionized, is mounted on the back wall of the ion source arc chamber and is bombarded by returning energetic low-charged gas ions that fail to cross the initial accelerating gap between the ion source and the accelerating electrode. Some of the atoms that are dislodged from the plate by the returning gas ions become ionized and are extracted as a useful beam of heavy ions. (auth)

  2. Complexation-induced supramolecular assembly drives metal-ion extraction.

    PubMed

    Ellis, Ross J; Meridiano, Yannick; Muller, Julie; Berthon, Laurence; Guilbaud, Philippe; Zorz, Nicole; Antonio, Mark R; Demars, Thomas; Zemb, Thomas

    2014-09-26

    Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts. PMID:25169678

  3. Interaction of metal cations with functionalised hydrocarbons in the gas phase: further experimental evidence for solvation of metal ions by the hydrocarbon chain.

    PubMed

    van Huizen, Nick A; Luider, Theo M; Jobst, Karl J; Terlouw, Johan K; Holmes, John L; Burgers, Peter C

    2016-01-01

    Relative affinity measurements of monovalent metal ions (= Li(+), Cu(+) and Ag(+)) towards aliphatic amines, alcohols and methyl alkanoates (P) have been performed using the kinetic method on the dissociation of metal bound dimer ions of the type P(1)-M(+)-P(2). It was found that the cations' affinity towards long chain (≥C(4) chain length) n- and s-alkylamines, n-alkanols and methyl n- alkanoates was unexpectedly enhanced. This is attributed to a bidentate interaction of the metal ion with the amine, alcohol or ester functional group and the aliphatic chain, paralleling earlier observations on metal bound nitriles. Methyl substitution at the functional group (s-alkylamines compared with n-alkylamines) serves to strengthen only the N•••M(+) bond, and this can be rationalized by the larger proton affinities of s-alkylamines compared to n-alkylamines. This substitution, however, has no effect on the metal ion-hydrocarbon bond. In contrast, methyl substitution remote from the functional group, as in iso-pentylamine, does lead to strengthening of the metal ion-hydrocarbon bond. The cuprous ion affinity of hexadecylamine, C(16)H(33)NH(2) was found to be as large as that for ethylenediamine (352 kJ mol(-1)), known to be a strong copper binding agent. It is argued that such a metal ion-hydrocarbon interaction does not occur in the metal bound dimers. PMID:27419899

  4. Ordering of metal-ion toxicities in different species--extrapolation to man

    SciTech Connect

    England, M.W.; Turner, J.E.; Hingerty, B.E.; Jacobson, K.B. )

    1989-01-01

    Our previous attempts to predict the toxicities of 24 metal ions for a given species, using physicochemical parameters associated with the ions, are summarized. In our current attempt we have chosen indicators of toxicity for biological systems of increasing levels of complexity--starting with individual biological molecules and ascending to mice as representative of higher-order animals. The numerical values for these indicators have been normalized to a scale of 100 for Mg{sup 2+} (essentially nontoxic) and 0 for Cd{sup 2+} (very toxic). To give predicted toxicities to humans, extrapolations across biological species have been made for each of the metal ions considered. The predicted values are then compared with threshold limit values (TLV) from the literature. Both methods for predicting toxicities have their advantages and disadvantages, and both have limited success for metal ions. However, the second approach suggests that the TLV for Cu{sup 2+} should be lower than that currently recommended.

  5. Adaptation of intertidal biofilm communities is driven by metal ion and oxidative stresses

    PubMed Central

    Zhang, Weipeng; Wang, Yong; Lee, On On; Tian, Renmao; Cao, Huiluo; Gao, Zhaoming; Li, Yongxin; Yu, Li; Xu, Ying; Qian, Pei-Yuan

    2013-01-01

    Marine organisms in intertidal zones are subjected to periodical fluctuations and wave activities. To understand how microbes in intertidal biofilms adapt to the stresses, the microbial metagenomes of biofilms from intertidal and subtidal zones were compared. The genes responsible for resistance to metal ion and oxidative stresses were enriched in both 6-day and 12-day intertidal biofilms, including genes associated with secondary metabolism, inorganic ion transport and metabolism, signal transduction and extracellular polymeric substance metabolism. In addition, these genes were more enriched in 12-day than 6-day intertidal biofilms. We hypothesize that a complex signaling network is used for stress tolerance and propose a model illustrating the relationships between these functions and environmental metal ion concentrations and oxidative stresses. These findings show that bacteria use diverse mechanisms to adapt to intertidal zones and indicate that the community structures of intertidal biofilms are modulated by metal ion and oxidative stresses. PMID:24212283

  6. Modified agricultural waste biomass with enhanced responsive properties for metal-ion remediation: a green approach

    NASA Astrophysics Data System (ADS)

    Mahajan, Garima; Sud, Dhiraj

    2012-12-01

    Dalbergia sissoo pods, a lignocellulosic nitrogenous waste biomass, was evaluated for sequestering of Cr(VI) from synthetic wastewater. Dalbergia sissoo pods (DSP) were used in three different forms, viz. natural (DSPN), impregnated in the form of hydrated beads (DSPB), and in carbonized form (DSPC) for comparative studies. Batch experiments were performed for the removal of hexavalent chromium. Effects of pH adsorbent dose, initial metal-ion concentration, stirring speed, and contact time were investigated. The removal of metal ions was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration, and other studied process parameters. Maximum metal removal for Cr(VI) was observed at pH 2.0. The experimental data were analyzed based on Freundlich and Langmuir adsorption isotherms. Kinetic studies indicated that the adsorption of metal ions followed a pseudo-second-order equation.

  7. Metal ions potentiate microglia responsiveness to endotoxin.

    PubMed

    Rachmawati, Dessy; Peferoen, Laura A N; Vogel, Daphne Y S; Alsalem, Inás W A; Amor, Sandra; Bontkes, Hetty J; von Blomberg, B Mary E; Scheper, Rik J; van Hoogstraten, Ingrid M W

    2016-02-15

    Oral metal exposure has been associated with diverse adverse reactions, including neurotoxicity. We showed previously that dentally applied metals activate dendritic cells (MoDC) via TLR4 (Ni, Co, Pd) and TLR3 (Au). It is still unknown whether the low levels of dental metals reaching the brain can trigger local innate cells or prime them to become more responsive. Here we tested whether dentally applied metals (Cr, Fe, Co, Ni, Cu, Zn, Au, Hg) activate primary human microglia in vitro and, as a model, monocytic THP-1-cells, in high non-toxic as well as near-physiological concentrations. In addition the effects of 'near-physiological' metal exposure on endotoxin (LPS) responsiveness of these cells were evaluated. IL-8 and IL-6 production after 24h was used as read out. In high, non-toxic concentrations all transition metals except Cr induced IL-8 and IL-6 production in microglia, with Ni and Co providing the strongest stimulation. When using near-physiological doses (up to 10× the normal plasma concentration), only Zn and Cu induced significant IL-8 production. Of note, the latter metals also markedly potentiated LPS responsiveness of microglia and THP-1 cells. In conclusion, transition metals activate microglia similar to MoDCs. In near-physiological concentrations Zn and Cu are the most effective mediators of innate immune activation. A clear synergism between innate responses to Zn/Cu and LPS was observed, shedding new light on the possible relation between oral metal exposure and neurotoxicity. PMID:26857501

  8. Sputtering and secondary ion emission properties of alkali metal films and adsorbed monolayers

    SciTech Connect

    Krauss, A R; Gruen, D M

    1980-01-01

    The secondary ion emission of alkali metal adsorbed monlayer and multilayer films has been studied. Profiling with sub-monolayer resolution has been performed by Auger, x-ray photoemission and secondary ion mass spectroscopy. Characteristic differences in the sputtering yields, and ion fraction have been observed which are associated with both the surface bonding properties and the mechanism leading to the formation of secondary ions. By sputtering with a negative bias applied to the sample, positive secondary ions are returned to the surface, resulting in a reduced sputter-induced erosion rate. Comparison with the results obtained with K and Li overlayers sputtered without sample bias provides an experimental value of both the total and secondary ion sputtering yields. The first and second monolayers can be readily identified and the first monolayer exhibits a lower sputtering yield and higher secondary ion fraction. This result is related to adsorption theory and measured values are compared with those obtained by thermal desorption measurements.

  9. Metal ion coupled protein folding and allosteric motions

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    2014-03-01

    Many proteins need the help of cofactors for their successful folding and functioning. Metal ions, i.e., Zn2+, Ca2+, and Mg2+ etc., are typical biological cofactors. Binding of metal ions can reshape the energy landscapes of proteins, thereby modifying the folding and allosteric motions. For example, such binding may make the intrinsically disordered proteins have funneled energy landscapes, consequently, ensures their spontaneous folding. In addition, the binding may activate certain biological processes by inducing related conformational changes of regulation proteins. However, how the local interactions involving the metal ion binding can induce the global conformational motions of proteins remains elusive. Investigating such question requires multiple models with different details, including quantum mechanics, atomistic models, and coarse grained models. In our recent work, we have been developing such multiscale methods which can reasonably model the metal ion binding induced charge transfer, protonation/deprotonation, and large conformational motions of proteins. With such multiscale model, we elucidated the zinc-binding induced folding mechanism of classical zinc finger and the calcium-binding induced dynamic symmetry breaking in the allosteric motions of calmodulin. In addition, we studied the coupling of folding, calcium binding and allosteric motions of calmodulin domains. In this talk, I will introduce the above progresses on the metal ion coupled protein folding and allosteric motions. We thank the finacial support from NSFC and the 973 project.

  10. Colored thin films for specific metal ion detection.

    PubMed

    Schauer, Caroline L; Chen, Mu-San; Price, Ronald R; Schoen, Paul E; Ligler, Frances S

    2004-08-15

    This paper describes the investigation of chitosan and poly(allylamine) (PAH) for the creation of a multi-film, color-based dipstick for the detection of metal ions in solution. Thin, colored films of chitosan and PAH cross-linked with hexamethylene 1,6-di(aminocarboxysulfonate) (HDACS) are created where color is due to film thickness and optical interference effects. The films are investigated for their ability to selectively detect aqueous metal ions via changes in thickness and/or color. Chitosan-HDACS films were selective for Cr(VI) over all other metal ions tested including Cr(acac)3 and Cr(NO3)3 x 9H2O, and PAH-HDACS films were selective for Cu(II) and Cu(I) salts over all other metal ions tested. The irreversible, selective changes due to metal ion solutions were not caused by varying the pH. Potomac River water was also tested using the two films, with results indicating the presence of Cu(II) in the aqueous sample. PMID:15382871

  11. Membranes Remove Metal Ions Fron Industrial Liquids

    NASA Technical Reports Server (NTRS)

    Hsu, W. P. L.; May, C.

    1983-01-01

    Use of membrane films affords convenient and economical alternative for removing and recovering metal cations present in low concentrations from large quantities of liquid solutions. Possible applications of membrane films include use in analytical chemistry for determination of small amounts of toxic metallic impurities in lakes, streams, and municipal effluents. Also suitable for use as absorber of certain pollutant gases and odors present in confined areas.

  12. Decreased fluidity of cell membranes causes a metal ion deficiency in recombinant Saccharomyces cerevisiae producing carotenoids.

    PubMed

    Liu, Peitong; Sun, Liang; Sun, Yuxia; Shang, Fei; Yan, Guoliang

    2016-04-01

    The genome-wide transcriptional responses of S. cerevisiae to heterologous carotenoid biosynthesis were investigated using DNA microarray analysis. The results show that the genes involved in metal ion transport were specifically up-regulated in the recombinant strain, and metal ions, including Cu(2+), Fe(2+), Mn(2+), and Mg(2+), were deficient in the recombinant strain compared to the ion content of the parent strain. The decrease in metal ions was ascribed to a decrease in cell membrane (CM) fluidity caused by lower levels of unsaturated fatty acids and ergosterol. This was confirmed by the observation that metal ion levels were restored when CM fluidity was increased by supplying linoleic acid. In addition, a 24.3 % increase in the β-carotene concentration was observed. Collectively, our results suggest that heterologous production of carotenoids in S. cerevisiae can induce cellular stress by rigidifying the CM, which can lead to a deficiency in metal ions. Due to the importance of CM fluidity in cellular physiology, maintaining normal CM fluidity might be a potential approach to improving carotenoid production in genetically engineered S. cerevisiae. PMID:26749524

  13. Process for modifying the metal ion sorption capacity of a medium

    DOEpatents

    Lundquist, Susan H.

    2002-01-01

    A process for modifying a medium is disclosed that includes treating a medium having a metal ion sorption capacity with a solution that includes: A) an agent capable of forming a complex with metal ions; and B) ions selected from the group consisting of sodium ions, potassium ions, magnesium ions, and combinations thereof, to create a medium having an increased capacity to sorb metal ions relative to the untreated medium.

  14. BODIPY-based fluorometric sensor array for the highly sensitive identification of heavy-metal ions.

    PubMed

    Niu, Li-Ya; Li, Hui; Feng, Liang; Guan, Ying-Shi; Chen, Yu-Zhe; Duan, Chun-Feng; Wu, Li-Zhu; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-05-01

    A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library. PMID:23601979

  15. Serum Metal Ion Concentrations in Paediatric Patients following Total Knee Arthroplasty Using Megaprostheses

    PubMed Central

    Friesenbichler, Jörg; Sadoghi, Patrick; Maurer-Ertl, Werner; Szkandera, Joanna; Glehr, Mathias; Ogris, Kathrin; Wolf, Matthias; Weger, Christian; Leithner, Andreas

    2014-01-01

    The purpose of this study was to determine the concentrations of cobalt, chromium, and molybdenum in the serum of paediatric tumour patients after fixed hinge total knee arthroplasty. Further, these metal ion levels were compared with serum metal ion levels of patients with other orthopaedic devices such as hip and knee prostheses with metal-on-metal or metal-on-polyethylene articulation to find differences between anatomical locations, abrasion characteristics, and bearing surfaces. After an average follow-up of 108 months (range: 67 to 163) of 11 paediatric patients with fixed hinge total knee arthroplasty, the mean concentrations for Co and Cr were significantly increased while Mo was within the limits compared to the upper values from the reference laboratory. Furthermore, these serum concentrations were significantly higher compared to patients with a standard rotating hinge device (P = 0.002 and P < 0.001) and preoperative controls (P < 0.001). On the other hand, the serum levels of patients following MoM THA or rotating hinge arthroplasty using megaprostheses were higher. Therefore, periodic long-term follow-ups are recommended due to the rising concerns about systemic metal ion exposure in the literature. Upon the occurrence of adverse reactions to metal debris the revision of the fixed hinge implant should be considered. PMID:25276819

  16. Theoretical study of metal noble-gas positive ions

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1989-01-01

    Theoretical calculations have been performed to determine the spectroscopic constant for the ground and selected low-lying electronic states of the transition-metal noble-gas ions Var(+), FeAr(+), CoAr(+), CuHe(+), CuAr(+), and CuKr(+). Analogous calculations have been performed for the ground states of the alkali noble-gas ions LiAr(+), LiKr(+), NaAr(+), and KAr(+) and the alkaline-earth noble-gas ion MgAr(+) to contrast the difference in binding energies between the simple and transition-metal noble-gas ions. The binding energies increase with increasing polarizability of the noble-gas ions, as expected for a charge-induced dipole bonding mechanism. It is found that the spectroscopic constants of the X 1Sigma(+) states of the alkali noble-gas ions are well described at the self-consistent field level. In contrast, the binding energies of the transition-metal noble-gas ions are substantially increased by electron correlation.

  17. Localized ion milling of metallic and ceramic TEM specimens

    SciTech Connect

    Fisher, A.T.; Bentley, J.

    1986-01-01

    The utility of localized ion milling in the preparation of metallic and ceramic specimens for TEM and AEM is being evaluated from the standpoint of optimizing procedures and identifying limitations and milling characteristics. The equipment used was a Gatan model 645 precision ion milling system (PIMS). This device is a scanning ion beam instrument with which selected areas of a sample can be imaged by either secondary electron or secondary ion signals and selectively ion milled in a small region within the imaged area. The 1 to 10 keV ion beam can be focussed to a 2 ..mu..m spot. Specimens are thinned without removing them from the electron microscope specimen holder.

  18. Analysis of Accumulating Ability of Heavy Metals in Lotus (Nelumbo nucifera) Improved by Ion Implantation

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhua; Wang, Naiyan; Zhang, Fengshou

    2012-05-01

    Heavy metals have seriously contaminated soil and water, and done harm to public health. Academician WANG Naiyan proposed that ion-implantation technique should be exploited for environmental bioremediation by mutating and breeding plants or microbes. By implanting N+ into Taikonglian No.1, we have selected and bred two lotus cultivars, Jingguang No.1 and Jingguang No.2. The present study aims at analyzing the feasibility that irradiation can be used for remediation of soil and water from heavy metals. Compared with parent Taikonglian No.1, the uptaking and accumulating ability of heavy metals in two mutated cultivars was obviously improved. So ion implantation technique can indeed be used in bioremediation of heavy metals in soil and water, but it is hard to select and breed a cultivar which can remedy the soil and water from all the heavy metals.

  19. Reducing hazardous heavy metal ions using mangium bark waste.

    PubMed

    Khabibi, Jauhar; Syafii, Wasrin; Sari, Rita Kartika

    2016-08-01

    The objective of this study was to evaluate the characteristics of mangium bark and its biosorbent ability to reduce heavy metal ions in standard solutions and wastewater and to assess changes in bark characteristics after heavy metal absorption. The experiments were conducted to determine heavy metal absorption from solutions of heavy metals alone and in mixtures as well as from wastewater. The results show that mangium bark can absorb heavy metals. Absorption percentages and capacities from single heavy metal solutions showed that Cu(2+) > Ni(2+) > Pb(2+) > Hg(2+), while those from mixture solutions showed that Hg(2+) > Cu(2+) > Pb(2+) > Ni(2+). Wastewater from gold mining only contained Cu, with an absorption percentage and capacity of 42.87 % and 0.75 mg/g, respectively. The highest absorption percentage and capacity of 92.77 % and 5.18 mg/g, respectively, were found for Hg(2+) in a mixture solution and Cu(2+) in single-metal solution. The Cu(2+) absorption process in a single-metal solution changed the biosorbent characteristics of the mangium bark, yielding a decreased crystalline fraction; changed transmittance on hydroxyl, carboxyl, and carbonyl groups; and increased the presence of Cu. In conclusion, mangium bark biosorbent can reduce hazardous heavy metal ions in both standard solutions and wastewater. PMID:27179811

  20. Low coefficient of thermal expansion polyimides containing metal ion additives

    SciTech Connect

    Stoakley, D.M.; St.Clair, A.K. )

    1992-07-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The CTE's of conventional polyimides range from 30 to 60 ppm/C. Approaches that have been reported to lower their CTE's include linearizing the polymer molecular structure and orienting the polyimide film. This current study involves the incorporation of metal ion-containing additives into polyimides and has resulted in significantly lowered CTE's. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12% to over 100% depending on the choice of additive and its concentration.

  1. Ion exchange properties of novel hydrous metal oxide materials

    SciTech Connect

    Gardner, T.J.; McLaughlin, L.I.

    1996-12-31

    Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.

  2. Low coefficient of thermal expansion polyimides containing metal ion additives

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, A. K.

    1992-01-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The incorporation of metal ion-containing additives into polyimides, resulting in significantly lowered CTE's, has been studied. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12 percent to over 100 percent depending on the choice of additive and its concentration.

  3. Porous metal oxide microspheres from ion exchange resin

    NASA Astrophysics Data System (ADS)

    Picart, S.; Parant, P.; Caisso, M.; Remy, E.; Mokhtari, H.; Jobelin, I.; Bayle, J. P.; Martin, C. L.; Blanchart, P.; Ayral, A.; Delahaye, T.

    2015-07-01

    This study is devoted to the synthesis and the characterization of porous metal oxide microsphere from metal loaded ion exchange resin. Their application concerns the fabrication of uranium-americium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Those mixed oxide ceramics are one of the materials envisaged for americium transmutation in sodium fast neutron reactors. The advantage of such microsphere precursor compared to classical oxide powder is the diminution of the risk of fine dissemination which can be critical for the handling of highly radioactive powders such as americium based oxides and the improvement of flowability for the filling of compaction chamber. Those millimetric oxide microspheres incorporating uranium and americium were synthesized and characterizations showed a very porous microstructure very brittle in nature which occurred to be adapted to shaping by compaction. Studies allowed to determine an optimal heat treatment with calcination temperature comprised between 700-800 °C and temperature rate lower than 2 °C/min. Oxide Precursors were die-pressed into pellets and then sintered under air to form regular ceramic pellets of 95% of theoretical density (TD) and of homogeneous microstructure. This study validated thus the scientific feasibility of the CRMP process to prepare bearing americium target in a powder free manner.

  4. Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal-organic ionic molten salts.

    PubMed

    Chen, Fangfang; Forsyth, Maria

    2016-07-28

    Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion transference number at concentrations approaching 50 mol% Li(+) or Na(+), relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali-anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li(+) in a phosphonium ionic liquid, thus an increasing alkali transference number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions. PMID:27375042

  5. Comet Encke: Meteor metallic ion identification by mass spectrometer

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Aikin, A. C.

    1972-01-01

    Metal ions including Na-40(+), Mg-24(+), Si-28(+), K-39(+), Ca-40(+), Sc-45(+), Cr-52(+), Fe-56(+), and Ni-58(+) were detected in the upper atmosphere during the beta Taurids meteor shower. Abundances of these ions relative to Si(+) show agreement in most instances with chondrites. A notable exception is 45(+), which is Sc(+), is 100 times more abundant than neutral scandium found in chondrites.

  6. Comet encke: meteor metallic ion identification by mass spectrometer.

    PubMed

    Goldberg, R A; Aikin, A C

    1973-04-20

    Metal ions including 23(+) (Na(+)), 24(+) (Mg(+)) 28(+) (Si(+)), 39(+) (K(+)), 40(+) (Ca(+)), 45(+) (Sc(+)), 52(+) Cr(+)). 56(+) (Fe(+)), and 58(+) (Ni(+)) have been detected in the upper atmosphere during the period of the Beta Taurids meteor shower. The abundances of these ions relative to Si(+) show, agreement in most instances with abundances in chondrites. A notable exception is 45(+), which, if it is Sc(+), is 100 times more abundant than neutral scandium found in chondrites. PMID:17816288

  7. Adsorbent for metal ions and method of making and using

    DOEpatents

    White, Lloyd R.; Lundquist, Susan H.

    2000-01-01

    A method comprises the step of spray-drying a solution or slurry comprising (alkali metal or ammonium) (metal) hexacyanoferrate particles in a liquid, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size in the range of 1 to 500 micrometers, said particles being active towards Cs ions. The particles, which can be of a single salt or a combination of salts, can be used free flowing, in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove Cs ions from aqueous solutions.

  8. Adsorbent for metal ions and method of making and using

    DOEpatents

    White, L.R.; Lundquist, S.H.

    1999-08-10

    A method comprises the step of spray-drying a solution or slurry comprising (alkali metal or ammonium) (metal) hexacyanoferrate particles in a liquid, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size in the range of 1 to 500 micrometers, said particles being active towards Cs ions. The particles, which can be of a single salt or a combination of salts, can be used free flowing, in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove Cs ions from aqueous solutions. 2 figs.

  9. Adsorbent for metal ions and method of making and using

    DOEpatents

    White, Lloyd R.; Lundquist, Susan H.

    1999-01-01

    A method comprises the step of spray-drying a solution or slurry comprising (alkali metal or ammonium) (metal) hexacyanoferrate particles in a liquid, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size in the range of 1 to 500 micrometers, said particles being active towards Cs ions. The particles, which can be of a single salt or a combination of salts, can be used free flowing, in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove Cs ions from aqueous solutions.

  10. Smart responsive microcapsules capable of recognizing heavy metal ions.

    PubMed

    Pi, Shuo-Wei; Ju, Xiao-Jie; Wu, Han-Guang; Xie, Rui; Chu, Liang-Yin

    2010-09-15

    Smart responsive microcapsules capable of recognizing heavy metal ions are successfully prepared with oil-in-water-in-oil double emulsions as templates for polymerization in this study. The microcapsules are featured with thin poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)) membranes, and they can selectively recognize special heavy metal ions such as barium(II) or lead(II) ions very well due to the "host-guest" complexation between the BCAm receptors and barium(II) or lead(II) ions. The stable BCAm/Ba(2+) or BCAm/Pb(2+) complexes in the P(NIPAM-co-BCAm) membrane cause a positive shift of the volume phase transition temperature of the crosslinked P(NIPAM-co-BCAm) hydrogel to a higher temperature, and the repulsion among the charged BCAm/Ba(2+) or BCAm/Pb(2+) complexes and the osmotic pressure within the P(NIPAM-co-BCAm) membranes result in the swelling of microcapsules. Induced by recognizing barium(II) or lead(II) ions, the prepared microcapsules with P(NIPAM-co-BCAm) membranes exhibit isothermal and significant swelling not only in outer and inner diameters but also in the membrane thickness. The proposed microcapsules in this study are highly attractive for developing smart sensors and/or carriers for detection and/or elimination of heavy metal ions. PMID:20656104

  11. Metal-Ion Additives Reduce Thermal Expansion Of Polyimides

    NASA Technical Reports Server (NTRS)

    Stoakley, Diane M.; St. Clair, Anne K.; Emerson, Burt R., Jr.; Willis, George L.

    1994-01-01

    Polyimides widely used as high-performance polymers because of their excellent thermal stability and toughness. However, their coefficients of thermal expansion (CTE's) greater than those of metals, ceramics, and glasses. Decreasing CTE's of polyimides increase usefulness for aerospace and electronics applications in which dimensional stability required. Additives containing metal ions reduce coefficients of thermal expansion of polyimides. Reductions range from 11 to over 100 percent.

  12. Existence of efficient divalent metal ion-catalyzed and inefficient divalent metal ion-independent channels in reactions catalyzed by a hammerhead ribozyme

    PubMed Central

    Zhou, Jing-Min; Zhou, De-Min; Takagi, Yasuomi; Kasai, Yasuhiro; Inoue, Atsushi; Baba, Tadashi; Taira, Kazunari

    2002-01-01

    The hammerhead ribozyme is generally accepted as a well characterized metalloenzyme. However, the precise nature of the interactions of the RNA with metal ions remains to be fully defined. Examination of metal ion-catalyzed hammerhead reactions at limited concentrations of metal ions is useful for evaluation of the role of metal ions, as demonstrated in this study. At concentrations of Mn2+ ions from 0.3 to 3 mM, addition of the ribozyme to the reaction mixture under single-turnover conditions enhances the reaction with the product reaching a fixed maximum level. Further addition of the ribozyme inhibits the reaction, demonstrating that a certain number of divalent metal ions is required for proper folding and also for catalysis. At extremely high concentrations, monovalent ions, such as Na+ ions, can also serve as cofactors in hammerhead ribozyme-catalyzed reactions. However, the catalytic efficiency of monovalent ions is extremely low and, thus, high concentrations are required. Furthermore, addition of monovalent ions to divalent metal ion-catalyzed hammerhead reactions inhibits the divalent metal ion-catalyzed reactions, suggesting that the more desirable divalent metal ion–ribozyme complexes are converted to less desirable monovalent metal ion–ribozyme complexes via removal of divalent metal ions, which serve as a structural support in the ribozyme complex. Even though two channels appear to exist, namely an efficient divalent metal ion-catalyzed channel and an inefficient monovalent metal ion-catalyzed channel, it is clear that, under physiological conditions, hammerhead ribozymes are metalloenzymes that act via the significantly more efficient divalent metal ion-dependent channel. Moreover, the observed kinetic data are consistent with Lilley’s and DeRose’s two-phase folding model that was based on ground state structure analyses. PMID:12034824

  13. How do energetic ions damage metallic surfaces?

    SciTech Connect

    Osetskiy, Yury N.; Calder, Andrew F.; Stoller, Roger E.

    2015-02-20

    Surface modification under bombardment by energetic ions observed under different conditions in structural and functional materials and can be either unavoidable effect of the conditions or targeted modification to enhance materials properties. Understanding basic mechanisms is necessary for predicting properties changes. The mechanisms activated during ion irradiation are of atomic scale and atomic scale modeling is the most suitable tool to study these processes. In this paper we present results of an extensive simulation program aimed at developing an understanding of primary surface damage in iron by energetic particles. We simulated 25 keV self-ion bombardment of Fe thin films with (100) and (110) surfaces at room temperature. A large number of simulations, ~400, were carried out allow a statistically significant treatment of the results. The particular mechanism of surface damage depends on how the destructive supersonic shock wave generated by the displacement cascade interacts with the free surface. Three basic scenarios were observed, with the limiting cases being damage created far below the surface with little or no impact on the surface itself, and extensive direct surface damage on the timescale of a few picoseconds. In some instances, formation of large <100> vacancy loops beneath the free surface was observed, which may explain some earlier experimental observations.

  14. How do energetic ions damage metallic surfaces?

    DOE PAGESBeta

    Osetskiy, Yury N.; Calder, Andrew F.; Stoller, Roger E.

    2015-02-20

    Surface modification under bombardment by energetic ions observed under different conditions in structural and functional materials and can be either unavoidable effect of the conditions or targeted modification to enhance materials properties. Understanding basic mechanisms is necessary for predicting properties changes. The mechanisms activated during ion irradiation are of atomic scale and atomic scale modeling is the most suitable tool to study these processes. In this paper we present results of an extensive simulation program aimed at developing an understanding of primary surface damage in iron by energetic particles. We simulated 25 keV self-ion bombardment of Fe thin films withmore » (100) and (110) surfaces at room temperature. A large number of simulations, ~400, were carried out allow a statistically significant treatment of the results. The particular mechanism of surface damage depends on how the destructive supersonic shock wave generated by the displacement cascade interacts with the free surface. Three basic scenarios were observed, with the limiting cases being damage created far below the surface with little or no impact on the surface itself, and extensive direct surface damage on the timescale of a few picoseconds. In some instances, formation of large <100> vacancy loops beneath the free surface was observed, which may explain some earlier experimental observations.« less

  15. Removal and recovery of toxic metal ions from aqueous waste sites using polymer pendant ligands

    SciTech Connect

    Fish, D.

    1996-10-01

    The purpose of this project is to investigate the use of polymer pendant ligand technology to remove and recover toxic metal ions from DOE aqueous waste sites. Polymer pendant lgiands are organic ligands, anchored to crosslinked, modified divinylbenzene-polystyrene beads, that can selectively complex metal ions. The metal ion removal step usually occurs through a complexation or ion exchange phenomena, thus recovery of the metal ions and reuse of the beads is readily accomplished.

  16. Metal ion effects on enolase activity

    SciTech Connect

    Lee, M.E.; Nowak, T.

    1986-05-01

    Most metal binding studies with yeast enolase suggest that two metals per monomer are required for catalytic activity. The functions of metal I and metal II have not been unequivocally defined. In a series of kinetic experiments where the concentration of MgII is kept constant at subsaturating levels (1mM), the addition of MnII or of ZnII gives a hyperbolic decrease in activity. The final velocity of these mixed metal systems is the same velocity obtained with either only MnII or ZnII respectively. The concentration of MnII (40 ..mu..M) or of Zn (2..mu..M) which gives half maximal effect in the presence of (1mM) MgII is approximately the same as the Km' value for MnII (9..mu..M) or ZnII (3..mu..M) respectively. Direct binding of MnII to enolase in the absence and presence of MgII shows that MnII and MgII compete for the same metal site on enolase. In the presence of 2-phosphoglycerate (2-PGA) and MgII, only a single site is occupied by MnII. Results suggest MnII at site I and MgII at site II. PRR and high resolution /sup 1/H and /sup 31/P NMR studies of enzyme-ligand complexes containing MnII and MgII and MnII are consistent with this model. /sub 31/P measurements allow a measure of the equilibrium constant (0.36) for enolase. Saturation transfer measurements yield net rate constants (k/sub f/ = 0.49s/sup -1/; k/sub r/ = 1.3s/sup -1/) for the overall reaction. These values are smaller than k/sub cat/ (38s/sup -1/) measured under analogous conditions. The cation at site I appears to determine catalytic activity.

  17. Multidiagnostic analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    SciTech Connect

    Anoop, K. K. Bruzzese, R.; Amoruso, S.; Polek, M. P.; Harilal, S. S.

    2015-02-28

    The dynamics of ions in ultrafast laser ablation of metals is studied over fluences ranging from the ablation threshold up to ≈75 J/cm{sup 2} by means of three well-established diagnostic techniques. Langmuir probe, Faraday cup, and spectrally resolved intensified charge coupled device imaging simultaneously monitored the ions produced during ultrafast laser ablation of a pure copper target with 800 nm, ≈50 fs, Ti: Sapphire laser pulses. The fluence dependence of ion yield is analyzed, resulting in the observance of three different regimes. The specific ion yield shows a maximum at about 4–5 J/cm{sup 2}, followed by a gradual reduction and a transition to a high-fluence regime above ≈50 J/cm{sup 2}. The fluence dependence of the copper ions angular distribution is also analyzed, observing a gradual increase in forward-peaking of Cu ions for fluences up to ≈10 J/cm{sup 2}. A broader ion component is observed at larger angles for fluences larger than ≈10 J/cm{sup 2}. Finally, an experimental characterization of the ionic angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ≈66 J/cm{sup 2}. Interestingly, the ion emission from the volatile metals shows a narrow, forward-peaked distribution, and a high peak ion yield compared to the refractory metals. Moreover, the width of ionic angular distributions presents a striking correlation with the peak ion yield.

  18. DUHOCAMIS: a dual hollow cathode ion source for metal ion beams.

    PubMed

    Zhao, W J; Müller, M W O; Janik, J; Liu, K X; Ren, X T

    2008-02-01

    In this paper we describe a novel ion source named DUHOCAMIS for multiply charged metal ion beams. This ion source is derived from the hot cathode Penning ion gauge ion source (JINR, Dubna, 1957). A notable characteristic is the modified Penning geometry in the form of a hollow sputter electrode, coaxially positioned in a compact bottle-magnetic field along the central magnetic line of force. The interaction of the discharge geometry with the inhomogeneous but symmetrical magnetic field enables this device to be operated as hollow cathode discharge and Penning discharge as well. The main features of the ion source are the very high metal ion efficiency (up to 25%), good operational reproducibility, flexible and efficient operations for low charged as well as highly charged ions, compact setup, and easy maintenance. For light ions, e.g., up to titanium, well-collimated beams in the range of several tens of milliamperes of pulsed ion current (1 ms, 10/s) have been reliably performed in long time runs. PMID:18315181

  19. DUHOCAMIS: A dual hollow cathode ion source for metal ion beams

    SciTech Connect

    Zhao, W. J.; Mueller, M. W. O.; Janik, J.; Liu, K. X.; Ren, X. T.

    2008-02-15

    In this paper we describe a novel ion source named DUHOCAMIS for multiply charged metal ion beams. This ion source is derived from the hot cathode Penning ion gauge ion source (JINR, Dubna, 1957). A notable characteristic is the modified Penning geometry in the form of a hollow sputter electrode, coaxially positioned in a compact bottle-magnetic field along the central magnetic line of force. The interaction of the discharge geometry with the inhomogeneous but symmetrical magnetic field enables this device to be operated as hollow cathode discharge and Penning discharge as well. The main features of the ion source are the very high metal ion efficiency (up to 25%), good operational reproducibility, flexible and efficient operations for low charged as well as highly charged ions, compact setup, and easy maintenance. For light ions, e.g., up to titanium, well-collimated beams in the range of several tens of milliamperes of pulsed ion current (1 ms, 10/s) have been reliably performed in long time runs.

  20. Depth resolution improvement in secondary ion mass spectrometry analysis using metal cluster complex ion bombardment

    SciTech Connect

    Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S.

    2006-07-31

    Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir{sub 4}(CO){sub 7}{sup +} as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of {approx}1 nm under 5 keV, 45 deg. condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5 keV with higher incident angles.

  1. Sensing Metal Ions with DNA Building Blocks: Fluorescent Pyridobenzimidazole Nucleosides

    PubMed Central

    Kim, Su Jeong; Kool, Eric T.

    2008-01-01

    We describe novel fluorescent N-deoxyribosides (1 and 2) having 2-pyrido-2-benzimidazole and 2-quino-2-benzimidazole as aglycones. The compounds were prepared from the previously unknown heterocyclic precursors and Hoffer’s chlorosugar, yielding alpha anomers as the chief products. X-ray crystal structures confirmed the geometry, and showed that the pyridine and benzimidazole ring systems deviated from coplanarity in the solid state by 154° and 140°, respectively. In methanol the compounds 1 and 2 had absorption maxima at 360 and 370 nm respectively, and emission maxima at 494 and 539 nm. Experiments revealed varied fluorescence responses of the nucleosides to a panel of seventeen monovalent, divalent and trivalent metal ions in methanol. One or both of the nucleosides showed significant changes with ten of the metal ions. The most pronounced spectral changes for ligand-nucleoside 1 included red shifts in fluorescence (Au+, Au3+), strong quenching (Cu2+, Ni2+, Pt2+), and in substantial enhancements in emission intensity coupled with redshifts (Ag+, Cd2+, Zn2+). The greatest spectral changes for ligand-nucleoside 2 included a redshift in fluorescence (Ag+), a blueshift (Cd2+), strong quenching (Pd2+, Pt2+), and in substantial enhancements in emission intensity coupled with a blueshift (Zn2+). The compounds could be readily incorporated into oligodeoxynucleotides, where an initial study revealed that they retained sensitivity to metal ions in aqueous solution, and demonstrated possible cooperative sensing behavior with several ions. The two free nucleosides alone can act as differential sensors for at multiple metal ions, and they are potentially useful monomers for contributing metal ion sensing capability to DNAs. PMID:16669686

  2. Metal ions affecting the gastrointestinal system including the liver.

    PubMed

    Naughton, Declan P; Nepusz, Tamás; Petroczi, Andrea

    2011-01-01

    In the present context, metal ions can be categorized into several classes including those that are essential for life and those that have no known biological function and thus can be considered only as potentially hazardous. Many complexities arise with regard to metal toxicity and there is a paucity of studies relating to many metals which are frequent components of the diet. For many people ingestion of mineral supplements is considered a risk-free health choice despite growing evidence to the contrary. Numerous approaches have been developed to assess risk associated with ingestion of metal ions. These include straightforward estimation of safe limits such as oral reference dose which are often based on data derived from animal experiments. More convoluted approaches such as the Target Hazard Quotient involve assessment of hazard with frequent exposure over long durations such as a lifetime. The latter calculation also affords facile consideration of the effects of many metals together. In many cases, rigorous data are unavailable, hence, large factors of uncertainty are employed to relate risk to humans. Owing to the nature of metal toxicity, data pertaining to the gastrointestinal tract and liver are often acquired from diseases of metal homeostasis or episodes of considerable metal overload. Whilst these studies provide evidence for mechanisms of metal-induced toxicity such as enhancing oxidative stress, extrapolation of these results to healthy individuals or patients with chronic inflammatory diseases is not straightforward. In summary, the diverse nature of metals and their effects on human tissues along with a paucity of studies on the full range of their effects, warrant further in-depth studies on the association of metals to ageing, chronic inflammatory diseases, and cancer. PMID:21473378

  3. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization.

    PubMed

    Lee, Chuping; Lu, I-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-09-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser. Graphical Abstract ᅟ. PMID:27306427

  4. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization

    NASA Astrophysics Data System (ADS)

    Lee, Chuping; Lu, I.-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-06-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser.

  5. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization

    NASA Astrophysics Data System (ADS)

    Lee, Chuping; Lu, I.-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-09-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser.

  6. Adsorption characteristics of metal ions on chitosan chemically modified by D-galactose

    SciTech Connect

    Kondo, Kazuo; Sumi, Hisaharu; Matsumoto, Michiaki

    1996-07-01

    The adsorption characteristics of metal ions on chitosan chemically modified by D-galactose were examined. The pH dependency on the distribution ratio was found to be affected by the valency of the metal ion, and the apparent adsorption equilibrium constants of the metal ions were determined. The order of adsorption of the metal ions is Ga > In > Nd > Eu for the trivalent metal ions and Cu > Ni > Co for the divalent metal ions. It is believed that amino and hydroxyl groups in the chitosan act as a chelating ligand.

  7. Laser-driven ion sources for metal ion implantation for the reduction of dry friction

    SciTech Connect

    Boody, F. P.; Juha, L.; Kralikova, B.; Krasa, J.; Laska, L.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Straka, P.; Perina, V.; Woryna, E.; Giersch, D.; Hoepfl, R.; Kelly, J. C.; Hora, H.

    1997-04-15

    The anomalously high ion currents and very high ionization levels of laser-produced plasmas give laser-driven ion sources significant advantages over conventional ion sources. In particular, laser-driven ion sources should provide higher currents of metal ions at lower cost, for implantation into solids in order to improve their material properties such as friction. The energy and charge distributions for Pb and Sn ions produced by ablation of solid targets with {approx}25 J, {approx}300 ps iodine laser pulses, resulting in up to 48-times ionized MeV ions, as well as the optimization of focus position, are presented. Implantation of these ions into Ck-45 steel, without electrostatic acceleration, produced profiles with two regions. Almost all of the ions were implanted in a near surface region a few nm deep. However, a small but significant number of ions were implanted as deep as could be measured with Rutherford backscattering (RBS), here 150 nm for Sn and 250 nm for Pb. For the implanted ion densities and profiles achieved, no change in the coefficient of friction was measured for either ion.

  8. Ion bombardment induced smoothing of amorphous metallic surfaces: Experiments versus computer simulations

    SciTech Connect

    Vauth, Sebastian; Mayr, S. G.

    2008-04-15

    Smoothing of rough amorphous metallic surfaces by bombardment with heavy ions in the low keV regime is investigated by a combined experimental-simulational study. Vapor deposited rough amorphous Zr{sub 65}Al{sub 7.5}Cu{sub 27.5} films are the basis for systematic in situ scanning tunneling microscopy measurements on the smoothing reaction due to 3 keV Kr{sup +} ion bombardment. The experimental results are directly compared to the predictions of a multiscale simulation approach, which incorporates stochastic rate equations of the Langevin type in combination with previously reported classical molecular dynamics simulations [Phys. Rev. B 75, 224107 (2007)] to model surface smoothing across length and time scales. The combined approach of experiments and simulations clearly corroborates a key role of ion induced viscous flow and ballistic effects in low keV heavy ion induced smoothing of amorphous metallic surfaces at ambient temperatures.

  9. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, Toshifumi; Kukacka, Lawrence E.; Horn, William H.

    1985-01-01

    Quick setting polymer concrete compositions with excellent structural properties are disclosed; these polymer concrete compositions are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate, which may be wet, and with a source of bivalent metallic ions.

  10. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.; Horn, W.H.

    1981-11-04

    Quick setting polymer concrete compositions which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

  11. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.; Horn, W.H.

    1983-05-13

    Quick setting polymer concrete compositions are described which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

  12. Principles Governing Metal Ion Selectivity in Ion Channel Proteins

    NASA Astrophysics Data System (ADS)

    Lim, Carmay

    2014-03-01

    Our research interests are to (i) unravel the principles governing biological processes and use them to identify novel drug targets and guide drug design, and (ii) develop new methods for studying macromolecular interactions. This talk will provide an overview of our work in these two areas and an example of how our studies have helped to unravel the principles underlying the conversion of Ca2+-selective to Na+-selective channels. Ion selectivity of four-domain voltage-gated Ca2+(Cav) and sodium (Nav) channels, which is controlled by the selectivity filter (SF, the narrowest region of an open pore), is crucial for electrical signaling. Over billions of years of evolution, mutation of the Glu from domain II/III in the EEEE/DEEA SF of Ca2+-selective Cav channels to Lys made these channels Na+-selective. This talk will delineate the physical principles why Lys is sufficient for Na+/Ca2+selectivity and why the DEKA SF is more Na+-selective than the DKEA one.

  13. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples. PMID:15766067

  14. Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

    NASA Astrophysics Data System (ADS)

    Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

    2014-12-01

    Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

  15. Method for removing metal ions from solution with titanate sorbents

    DOEpatents

    Lundquist, Susan H.; White, Lloyd R.

    1999-01-01

    A method for removing metal ions from solution comprises the steps of providing titanate particles by spray-drying a solution or slurry comprising sorbent titanates having a particle size up to 20 micrometers, optionally in the presence of polymer free of cellulose functionality as binder, said sorbent being active towards heavy metals from Periodic Table (CAS version) Groups IA, IIA, IB, IIB, IIIB, and VIII, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size distribution in the range of 1 to 500 micrometers. The particles can be used free flowing in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove metal ions from aqueous or organic liquid.

  16. Metal ion influence on eumelanin fluorescence and structure

    NASA Astrophysics Data System (ADS)

    Sutter, Jens-Uwe; Birch, David J. S.

    2014-06-01

    Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

  17. Chitosan removes toxic heavy metal ions from cigarette mainstream smoke

    NASA Astrophysics Data System (ADS)

    Zhou, Wen; Xu, Ying; Wang, Dongfeng; Zhou, Shilu

    2013-09-01

    This study investigated the removal of heavy metal ions from cigarette mainstream smoke using chitosan. Chitosan of various deacetylation degrees and molecular weights were manually added to cigarette filters in different dosages. The mainstream smoke particulate matter was collected by a Cambridge filter pad, digested by a microwave digestor, and then analyzed for contents of heavy metal ions, including As(III/V), Pb(II), Cd(II), Cr(III/VI) and Ni(II), by graphite furnace atomic absorption spectrometry (GFAAS). The results showed that chitosan had a removal effect on Pb(II), Cd(II), Cr(III/VI) and Ni(II). Of these, the percent removal of Ni(II) was elevated with an increasing dosage of chitosan. Chitosan of a high deace tylation degree exhibited good binding performance toward Cd(II), Cr(III/VI) and Ni(II), though with poor efficiency for Pb(II). Except As(III/V), all the tested metal ions showed similar tendencies in the growing contents with an increasing chitosan molecular weight. Nonetheless, the percent removal of Cr(III/VI) peaked with a chitosan molecular weight of 200 kDa, followed by a dramatic decrease with an increasing chitosan molecular weight. Generally, chitosan had different removal effects on four out of five tested metal ions, and the percent removal of Cd(II), Pb(II), Cr(III/VI) and Ni(II) was approximately 55%, 45%, 50%, and 16%, respectively. In a word, chitosan used in cigarette filter can remove toxic heavy metal ions in the mainstream smoke, improve cigarette safety, and reduce the harm to smokers.

  18. Modification of medical metals by ion implantation of copper

    NASA Astrophysics Data System (ADS)

    Wan, Y. Z.; Xiong, G. Y.; Liang, H.; Raman, S.; He, F.; Huang, Y.

    2007-10-01

    The effect of copper ion implantation on the antibacterial activity, wear performance and corrosion resistance of medical metals including 317 L of stainless steels, pure titanium, and Ti-Al-Nb alloy was studied in this work. The specimens were implanted with copper ions using a MEVVA source ion implanter with ion doses ranging from 0.5 × 10 17 to 4 × 10 17 ions/cm 2 at an energy of 80 keV. The antibacterial effect, wear rate, and inflexion potential were measured as a function of ion dose. The results obtained indicate that copper ion implantation improves the antibacterial effect and wear behaviour for all the three medical materials studied. However, corrosion resistance decreases after ion implantation of copper. Experimental results indicate that the antibacterial property and corrosion resistance should be balanced for medical titanium materials. The marked deteriorated corrosion resistance of 317 L suggests that copper implantation may not be an effective method of improving its antibacterial activity.

  19. Liquid metal ion source and alloy for ion emission of multiple ionic species

    DOEpatents

    Clark, Jr., William M.; Utlaut, Mark W.; Wysocki, Joseph A.; Storms, Edmund K.; Szklarz, Eugene G.; Behrens, Robert G.; Swanson, Lynwood W.; Bell, Anthony E.

    1987-06-02

    A liquid metal ion source and alloy for the simultaneous ion evaporation of arsenic and boron, arsenic and phosphorus, or arsenic, boron and phosphorus. The ionic species to be evaporated are contained in palladium-arsenic-boron and palladium-arsenic-boron-phosphorus alloys. The ion source, including an emitter means such as a needle emitter and a source means such as U-shaped heater element, is preferably constructed of rhenium and tungsten, both of which are readily fabricated. The ion sources emit continuous beams of ions having sufficiently high currents of the desired species to be useful in ion implantation of semiconductor wafers for preparing integrated circuit devices. The sources are stable in operation, experience little corrosion during operation, and have long operating lifetimes.

  20. Metal negative ion beam extraction from a radio frequency ion source

    SciTech Connect

    Kanda, S.; Yamada, N.; Kasuya, T.; Romero, C. F. P.; Wada, M.

    2015-04-08

    A metal ion source of magnetron magnetic field geometry has been designed and operated with a Cu hollow target. Radio frequency power at 13.56 MHz is directly supplied to the hollow target to maintain plasma discharge and induce self-bias to the target for sputtering. The extraction of positive and negative Cu ion beams have been tested. The ion beam current ratio of Cu{sup +} to Ar{sup +} has reached up to 140% when Ar was used as the discharge support gas. Cu{sup −} ion beam was observed at 50 W RF discharge power and at a higher Ar gas pressure in the ion source. Improvement of poor RF power matching and suppression of electron current is indispensable for a stable Cu{sup −} ion beam production from the source.

  1. In vitro cytotoxicity of metallic ions released from dental alloys.

    PubMed

    Milheiro, Ana; Nozaki, Kosuke; Kleverlaan, Cornelis J; Muris, Joris; Miura, Hiroyuki; Feilzer, Albert J

    2016-05-01

    The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in concentrations similar to those reported to be released from Pd-based dental alloys on mouse fibroblast cells. Metal salts were used to prepare seven solutions (concentration range 100 ppm-1 ppb) of the transition metals, such as Ni(II), Pd(II), Cu(II), and Ag(I), and the metals, such as Ga(III), In(III), and Sn(II). Cytotoxicity on mouse fibroblasts L929 was evaluated using the MTT assay. Ni, Cu, and Ag are cytotoxic at 10 ppm, Pd and Ga at 100 ppm. Sn and In were not able to induce cytotoxicity at the tested concentrations. Transition metals were able to induce cytotoxic effects in concentrations similar to those reported to be released from Pd-based dental alloys. Ni, Cu, and Ag were the most cytotoxic followed by Pd and Ga; Sn and In were not cytotoxic. Cytotoxic reactions might be considered in the etiopathogenesis of clinically observed local adverse reactions. PMID:25549610

  2. Mechanical property measurements on ion-irradiated metals

    SciTech Connect

    Zinkle, S.J.; Oliver, W.C.

    1986-08-01

    A recently developed mechanical properties microprobe (MPM) has been used to investigate strength and elastic modulus changes in ion-irradiated metals. The indenter load and its displacement are simultaneously monitored while the indentation is being made and also during unloading. Microindentation hardness measurements have been performed on ion-irradiated copper and Cu-0.15% Zr (AMZIRC). The depth dependence of the ion damage has been investigated in selected specimens which were prepared using a cross-section technique. This procedure allows a direct comparison to be made of hardness data from different irradiation depths while the indent size is held constant. The displacement damage associated with ion irradiation caused either hardening or softening, depending on the irradiation conditions and the material.

  3. Metal Ion Binding to Polypeptides Characterized by Irmpd Spectroscopy. Metal-Amide Nitrogen Binding and the Iminol Tautomerization.

    NASA Astrophysics Data System (ADS)

    Dunbar, Robert C.; Polfer, Nicolas; Berden, Giel; Oomens, Jos

    2012-06-01

    We have recently uncovered a new binding mode for the complexation of metal ions with gas-phase peptides. Termed the iminol mode, this binding mode is adopted by strongly binding divalent metal ions including Mg2+ and Ni2+. The metal ion displaces the amide hydrogen, which moves to protonate the amide carbonyl oxygen. A spectroscopic signature of the tautomerization is the disappearance of the characteristic Amide II band normally seen in peptide ion infrared spectra. We find that in peptides up to pentapeptides, multiple iminol binding can take place, such that all amide linkages are tautomerized to the iminol form, and chelate the metal ion. However, the iminol tautomerization depends on the nature of the metal ion, as will be discussed. Spectra of the ions were acquired by irradiating the cell of the Fourier-transform ion cyclotron resonance mass spectrometer with infrared light from the FELIX laser at wavelengths in the approximate range 500 to 1900 cm-1.

  4. Optical studies of ion-beam synthesized metal alloy nanoparticles

    SciTech Connect

    Magudapathy, P. Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  5. Peptide immobilisation on porous silicon surface for metal ions detection

    NASA Astrophysics Data System (ADS)

    Sam, Sabrina S.; Chazalviel, Jean-Noël Jn; Gouget-Laemmel, Anne Chantal Ac; Ozanam, François F.; Etcheberry, Arnaud A.; Gabouze, Nour-Eddine N.

    2011-06-01

    In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl- N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization. The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  6. Differential UV-spectroscopic studies of transition metal ion interaction with DNA and its monomers

    NASA Astrophysics Data System (ADS)

    Sorokin, V. A.; Sysa, I. V.; Valeev, V. A.; Gladchenko, G. O.; Degtyar, M. V.; Blagoi, Yu. P.

    1997-06-01

    Data are presented for the base atoms coordinating Cu 2+, Ni 2+, Cd 2+ ions in DNA and its monomers, which were derived from the analysis of the shapes of UVD spectra taken on metal complexes. The corresponding binding constants are found. The Ni 2+ and Cd 2+ ions are noted for a very weak, as compared to Cu 2+ ions, interaction with cytosine of nucleotides. As a result, Cd 2+ and Ni 2+ ions can cause only internal protonation of N3C in the GC pairs of DNA on their interaction with N7G. In the case of Cu 2+ ions this interaction leads to the quasi-Hoogsteen transition of the GC pairs.

  7. New Catalytic DNA Biosensors for Radionuclides and Metal ion

    SciTech Connect

    Yi Lu

    2008-03-01

    We aim to develop new DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides, such as uranium, technetium, and plutonium, and metal contaminants, such as lead, chromium, and mercury. The sensors will be highly sensitive and selective. They will be applied to on-site, real-time assessment of concentration, speciation, and stability of the individual contaminants before and during bioremediation, and for long-term monitoring of DOE contaminated sites. To achieve this goal, we have employed a combinatorial method called “in vitro selection” to search from a large DNA library (~ 1015 different molecules) for catalytic DNA molecules that are highly specific for radionuclides or other metal ions through intricate 3-dimensional interactions as in metalloproteins. Comprehensive biochemical and biophysical studies have been performed on the selected DNA molecules. The findings from these studies have helped to elucidate fundamental principles for designing effective sensors for radionuclides and metal ions. Based on the study, the DNA have been converted to fluorescent or colorimetric sensors by attaching to it fluorescent donor/acceptor pairs or gold nanoparticles, with 11 part-per-trillion detection limit (for uranium) and over million fold selectivity (over other radionuclides and metal ions tested). Practical application of the biosensors for samples from the Environmental Remediation Sciences Program (ERSP) Field Research Center (FRC) at Oak Ridge has also been demonstrated.

  8. Ultrafine Na-4-mica: uptake of alkali and alkaline earth metal cations by ion exchange.

    PubMed

    Kodama, Tatsuya; Ueda, Masahito; Nakamuro, Yumiko; Shimizu, Ken-ichi; Komarneni, Sridhar

    2004-06-01

    The cation exchange properties of alkali and alkaline earth metal cations at room temperature were investigated on an ultrafine, highly charged Na-4-mica (with the ideal mica composition Na4Mg6Al4Si4O20F4.xH2O). Ultrafine mica crystallites of 200 nm in size led to faster Sr2+ uptake kinetics in comparison to larger mica crystallites. The alkali metal ion (K+, Cs+, and Li+) exchange uptake was rapid, and complete exchange occurred within 30 min. For the alkaline earth metal ions Ba2+, Ca2+, and Mg2+, however, the exchange uptake required lengthy periods from 3 days to 4 weeks to be completed, similar to its Sr uptake, as previously reported. Kinetic models of the modified Freundlich and parabolic diffusion were examined for the experimental data on the Ba2+, Ca2+, and Mg2+ uptakes. The modified Freundlich model described well the Ba2+ ion uptake kinetics as well as that for the Sr2+ ion, while for the Ca2+ and Mg2+ ions the parabolic diffusion model showed better fitting. The alkali and alkaline earth ion exchange isotherms were also determined in comparison to the Sr2+ exchange isotherm. The thermodynamic equilibria for these cations were compared by using Kielland plots evaluated from the isotherms. PMID:15984251

  9. Liquid metal alloy ion sources—An alternative for focussed ion beam technology

    NASA Astrophysics Data System (ADS)

    Bischoff, Lothar; Mazarov, Paul; Bruchhaus, Lars; Gierak, Jacques

    2016-06-01

    Today, Focused Ion Beam (FIB) processing is nearly exclusively based on gallium Liquid Metal Ion Sources (LMIS). But, many applications in the μm- or nm range could benefit from ion species other than gallium: local ion implantation, ion beam mixing, ion beam synthesis, or Focused Ion Beam Lithography (IBL). Therefore, Liquid Metal Alloy Ion Sources (LMAIS) represent a promising alternative to expand the remarkable application fields for FIB. Especially, the IBL process shows potential advantages over, e.g., electron beam or other lithography techniques: direct, resistless, and three-dimensional patterning, enabling a simultaneous in-situ process control by cross-sectioning and inspection. Taking additionally into account that the used ion species influences significantly the physical and chemical nature of the resulting nanostructures—in particular, the electrical, optical, magnetic, and mechanic properties leading to a large potential application area which can be tuned by choosing a well suited LMAIS. Nearly half of the elements of the periodic table are recently available in the FIB technology as a result of continuous research in this area during the last forty years. Key features of a LMAIS are long life-time, high brightness, and stable ion current. Recent developments could make these sources feasible for nano patterning issues as an alternative technology more in research than in industry. The authors will review existing LMAIS, LMIS other than Ga, and binary and ternary alloys. These physical properties as well as the fabrication technology and prospective domains for modern FIB applications will similarly be reviewed. Other emerging ion sources will be also presented and their performances discussed.

  10. The Structure of the Metal Transporter Tp34 and its Affinity for Divalent Metal Ions

    NASA Astrophysics Data System (ADS)

    Knutsen, Gregory; Deka, Ranjit; Brautigam, Chad; Tomchick, Diana; Machius, Mischa; Norgard, Michael

    2007-10-01

    Tp34 is periplasmic membrane protein of the nonculitvatable spirochete Treponema pallidum, the pathogen of syphillis. It was proposed that Tp34 is a divalent metal transporter, but the identity of the preferred metal ion(s) was unclear. In this study we investigated the ability of divalent metal ions to induce rTp34 dimerization using hydrodynamic techniques and determine the crystal structure of metal bound forms. Using analytical ultracentrifugation sedimentation velocity experiments, we determined that cobalt is superior to nickel at inducing the dimerization of rTp34. rTp34 was crystallized and selected crystals were incubated at a pH 7.5 with CuSO4 and NiSO4. Diffraction experiments were conducted and the processed electron density maps showed that copper was bound to the major metal binding site as well as to three additional minor binding sites. By contrast nickel was only bound to the major metal binding site in one monomer and to three additional minor sites. These results along with previous findings support evidence of Tp34 being involved with metal transport and/or iron utilization.

  11. Humic colloid-borne natural polyvalent metal ions: dissociation experiment.

    PubMed

    Geckeis, H; Rabung, Th; Ngo Manh, T; Kim, J I; Beck, H P

    2002-07-01

    The natural association nature of the humic colloid-borne trace elements is investigated. Rare earth elements (REE) Th and U are chosen as naturally occurring representatives and chemical homologues for actinides of different oxidation states present in nuclear waste. Tri- and tetravalent elements in two investigated Gorleben groundwaters (Gohy-532 and -2227) almost exclusively occur as humic or fulvic colloid-borne species. Their desorption behavior from colloids is examined in the unperturbed groundwater (pH approximately 8) under anaerobic conditions (Ar/1% CO2) by addition of a chelating cation exchanger resin. Particularly, the dissociation process of naturally occurring Eu(III) in the groundwater is compared with the Eu(III) desorption from its humate complex prepared with purified Aldrich humic acid in a buffered aqueous solution at pH approximately 8. The Eu(III) dissociation from the groundwater colloids is found to be considerably slower than found for the humate complex synthesized in the laboratory. This suggests that under natural aquatic conditions the Eu(III) binding in colloids is chemically different from the simple humate complexation as observed in the laboratory experiment. The colloid characterization bythe size exclusion chromatography (SEC) and the flow field-flow fractionation (FFFF) indicates that natural colloid-borne trace elements are found predominantly in colloids of larger size (>15 nm in size), while Eu(III) in its humate complex is found mainly in colloids of hydrodynamic diameters <5 nm. The slower desorption kinetics and the larger colloid size suggest that the polyvalent metal ion binding in natural humic colloids is associated to polynucleation with other co-present trace metal ions. Radiotracer experiments reveal that isotopic equilibria with the naturally colloid-borne trace elements are not attained within a period of more than 100 days, indicating irreversible binding of at least a part of colloid-borne polyvalent trace

  12. Polymer filtration systems for dilute metal ion recovery

    SciTech Connect

    Smith, B.F.; Robison, T.W.; Jarvinen, G.D.

    1998-12-01

    Scientists at Los Alamos National Laboratory have developed a metal recovery system that meets the global treatment demands for all kinds of industrial and metal-processing streams. The Polymer Filtration (PF) System--a process that is easily operated and robust--offers metal-finishing businesses a convenient and inexpensive way to recover and recycle metal ions in-house, thus reducing materials costs, waste removal costs, and industrial liability. As a valuable economic and environmental asset, the PF System has been named a winner of a 1995 R and D 100 Award. These awards are presented annually by R and D Magazine to the one hundred most significant technical innovations of the year. The PF System is based on the use of water-soluble metal-binding polymers and on advanced ultrafiltration membranes. Customers for this technology will receive new soluble polymers, especially formulated for their waste stream, and the complete PF processing unit: a reaction reservoir, pumps, plumbing, controls, and the advanced ultrafiltration membranes, all in a skid mounted frame. Metal-bearing waste water is treated in the reaction reservoir, where the polymer binds with the metal ions under balanced acid/base conditions. The reservoir fluid is then pumped through the ultrafiltration system--a cartridge packed with ultrafiltration membranes shaped in hollow fibers. As the fluid travels inside the fiber, water and other small molecules--simple salts such as calcium and sodium, for example--pass through the porous membrane walls of the fibers and are discharged through the outlet as permeate. The polymer-bound metal, which is too large to pass through the pores, is both purified and concentrated inside the hollow fibers and is returned to the fluid reservoir for further waste water treatment.

  13. Alkali-Metal-Ion-Functionalized Graphene Oxide as a Superior Anode Material for Sodium-Ion Batteries.

    PubMed

    Wan, Fang; Li, Yu-Han; Liu, Dai-Huo; Guo, Jin-Zhi; Sun, Hai-Zhu; Zhang, Jing-Ping; Wu, Xing-Long

    2016-06-01

    Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na(+) and e(-) transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li(+) , Na(+) , K(+) )-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g(-1) after 600 cycles at 1 A g(-1) ) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na-O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions. PMID:27136376

  14. Polydopamine-mediated surface-functionalization of graphene oxide for heavy metal ions removal

    SciTech Connect

    Dong, Zhihui; Zhang, Feng; Wang, Dong; Liu, Xia; Jin, Jian

    2015-04-15

    By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly via a Michael-Addition reaction and produced a PEI–PD/GO composite nanosheets. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, Hg{sup 2+} are up to 87, 106, 197, and 110 mg/g, respectively. To further make the GO based composite operable, PEI–PD/RGO aerogel was prepared through hydrothermal and achieved a high surface area up to 373 m{sup 2}/g. Although the adsorption capacity of PEI–PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI–PD/GO composite dispersion (38, 32, 95, 113 mg/g corresponding to Cu{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, and Hg{sup 2+}, respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater. - Graphical abstract: Polyethylenimine (PEI) brushes were grafted onto the surface of graphene oxide (GO) uniformly via a Michael-Addition reaction between the PEI and polydopamine interlayer coated on GO surface. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions compared to PEI-coated GO and pure GO. - Highlights: • We prepared polyethylenimine grafted polydopamine-mediated graphene oxide composites. • Introduction of PD layer increases metal ions adsorption capacity. • PEI–PD/RGO aerogel exhibited a superior adsorption performance. • PEI–PD/RGO aerogel can be recycled several times in a simple way.

  15. Ion beam mixing of metal/fluoropolymer interfaces

    SciTech Connect

    Dennis, D. L.; Giedd, R. E.; Wang, Y. Q.; Glass, G. A.

    1999-06-10

    Ion beam mixing of metals and polymers with very low dielectric constants such as Teflon can provide many applications in the area of electronic materials. This work is a study of the 'mixing' effect of 50 keV nitrogen implanted thin metal layers on Teflon PTFE (polytetrafluoroethylene) substrates. RBS analysis shows that the distribution of thin layers of copper and chromium (approximately 300-400 A thick) through the implant layer of the Teflon depends on the reactivity of the metal. As the implant fluence is increased, the distribution of metal atoms in the polymer matrix becomes concentrated over smaller ranges near the bottom of the implant layer. In situ RGA analysis during the implantation shows the liberation of an abundance of fluorine in many different forms. This is supported by results from a NRA experiment that shows the non-uniform concentration profile of fluorine throughout the implant layer. During the implantation process, the fluorine is released through the incident ion track leaving a carbon and metal rich region near the surface of the implant layer. The fluorine density increases with depth through the implant layer making a smooth transition to the undamaged bulk Teflon below. Low dielectric materials with highly conductive surfaces, such as this one, may provide an opportunity for a broad range of new microelectronic applications.

  16. Ion beam mixing of metal/fluoropolymer interfaces

    SciTech Connect

    Dennis, D.L.; Giedd, R.E.; Wang, Y.Q.; Glass, G.A.

    1999-06-01

    Ion beam mixing of metals and polymers with very low dielectric constants such as Teflon can provide many applications in the area of electronic materials. This work is a study of the {open_quotes}mixing{close_quotes} effect of 50 keV nitrogen implanted thin metal layers on Teflon PTFE (polytetrafluoroethylene) substrates. RBS analysis shows that the distribution of thin layers of copper and chromium (approximately 300-400 {Angstrom} thick) through the implant layer of the Teflon depends on the reactivity of the metal. As the implant fluence is increased, the distribution of metal atoms in the polymer matrix becomes concentrated over smaller ranges near the bottom of the implant layer. {ital In situ} RGA analysis during the implantation shows the liberation of an abundance of fluorine in many different forms. This is supported by results from a NRA experiment that shows the non-uniform concentration profile of fluorine throughout the implant layer. During the implantation process, the fluorine is released through the incident ion track leaving a carbon and metal rich region near the surface of the implant layer. The fluorine density increases with depth through the implant layer making a smooth transition to the undamaged bulk Teflon below. Low dielectric materials with highly conductive surfaces, such as this one, may provide an opportunity for a broad range of new microelectronic applications. {copyright} {ital 1999 American Institute of Physics.}

  17. Microbial metal-ion reduction and Mars: extraterrestrial expectations?

    PubMed

    Nealson, Kenneth H; Cox, B Lea

    2002-06-01

    Dissimilatory metal-ion-reducing bacteria (DMRB) can couple the reduction of a variety of different metal ions to cellular respiration and growth. The excitement of this metabolic group lies not only in the elucidation of a new type of metabolism, but also in the potential use of these abilities for the removal of toxic organics, and in their ability to reduce (and thus, detoxify) other toxic metals, such as U(VI) and Cr(VI). This review focuses on recent advances in the study of DMRB, including the use of external electron shuttles to enhance rates of metal reduction; genome sequencing and consequent genomic and proteomic analyses; new imaging approaches for high resolution analysis of both cells and chemical components; the demonstration of fractionation of stable isotopes of iron during iron reduction; and the elucidation of the types and patterns of secondary mineral formation during metal reduction. One of the secondary minerals is magnetite, the subject of intense controversy regarding the possibility of evidence for life from the Martian meteorite ALH84001. This review thus ends with a short consideration of the evidence for magnetic 'proof' of the existence of past life on Mars. PMID:12057684

  18. Metal fluoride coatings prepared by ion-assisted deposition

    NASA Astrophysics Data System (ADS)

    Bischoff, Martin; Sode, Maik; Gäbler, Dieter; Bernitzki, Helmut; Zaczek, Christoph; Kaiser, Norbert; Tünnermann, Andreas

    2008-09-01

    ArF lithography technology requires minimization of optical losses due to scattering and absorption. Consequently, it is necessary to optimize the coating process of metal fluorides. The properties of metal fluoride thin films are mainly affected by the deposition methods, their parameters (temperature and deposition rate) and the vacuum conditions. A substrate temperature of more than 300°C is a condition for high density and low water content of metal fluorides. Therefore, a substrate temperature of 150°C results in inhomogeneous films with high water content. Until now, the best results were achieved by boat evaporation. This paper will demonstrate that most of the common metal fluorides like MgF2, AlF3, and even LaF3 can be deposited by electron beam evaporation. In comparison to other deposition methods, the prepared thin films have the lowest absorption in the VUV spectral range. Furthermore, metal fluoride thin films were prepared by ion assistance. It will be demonstrated, that they have less water content, high packing density, and low absorption in the VUV spectral range. In this study, single layers of LaF3 and AlF3 and antireflection coatings were prepared by electron beam evaporation with and without ion-assistance. The mechanical, structural, and optical properties were examined and discussed.

  19. Metal Ion Toxins and Brain Aquaporin-4 Expression: An Overview.

    PubMed

    Ximenes-da-Silva, Adriana

    2016-01-01

    Metal ions such as iron, zinc, and manganese are essential to metabolic functions, protein synthesis, neurotransmission, and antioxidant neuroprotective mechanisms. Conversely, non-essential metals such as mercury and lead are sources of human intoxication due to occupational activities or environmental contamination. Essential or non-essential metal accumulation in the central nervous system (CNS) results in changes in blood-brain barrier (BBB) permeability, as well as triggering microglia activation and astrocyte reactivity and changing water transport through the cells, which could result in brain swelling. Aquaporin-4 is the main water channel in the CNS, is expressed in astrocyte foot processes in brain capillaries and along the circumventricular epithelium in the ventricles, and has important physiological functions in maintaining brain osmotic homeostasis and supporting brain excitability through regulation of the extracellular space. Some evidence has pointed to a role of AQP4 during metal intoxication in the brain, where it may act in a dual form as a neuroprotector or a mediator of the development of oxidative stress in neurons and astrocytes, resulting in brain swelling and neuronal damage. This mini-review presents the way some metal ions affect changes in AQP4 expression in the CNS and discuss the ways in which water transport in brain cells can be involved in brain damage. PMID:27313504

  20. Metal Ion Toxins and Brain Aquaporin-4 Expression: An Overview

    PubMed Central

    Ximenes-da-Silva, Adriana

    2016-01-01

    Metal ions such as iron, zinc, and manganese are essential to metabolic functions, protein synthesis, neurotransmission, and antioxidant neuroprotective mechanisms. Conversely, non-essential metals such as mercury and lead are sources of human intoxication due to occupational activities or environmental contamination. Essential or non-essential metal accumulation in the central nervous system (CNS) results in changes in blood-brain barrier (BBB) permeability, as well as triggering microglia activation and astrocyte reactivity and changing water transport through the cells, which could result in brain swelling. Aquaporin-4 is the main water channel in the CNS, is expressed in astrocyte foot processes in brain capillaries and along the circumventricular epithelium in the ventricles, and has important physiological functions in maintaining brain osmotic homeostasis and supporting brain excitability through regulation of the extracellular space. Some evidence has pointed to a role of AQP4 during metal intoxication in the brain, where it may act in a dual form as a neuroprotector or a mediator of the development of oxidative stress in neurons and astrocytes, resulting in brain swelling and neuronal damage. This mini-review presents the way some metal ions affect changes in AQP4 expression in the CNS and discuss the ways in which water transport in brain cells can be involved in brain damage. PMID:27313504

  1. Fibroblast Response to Lanthanoid Metal Ion Stimulation: Potential Contribution to Fibrotic Tissue Injury

    PubMed Central

    Jenkins, William; Perone, Patricia; Walker, Kyle; Bhagavathula, Narasimharao; Aslam, Muhammad Nadeem; DaSilva, Marissa; Dame, Michael K.; Varani, James

    2011-01-01

    The purpose of this study was to compare each of the 14 naturally occurring lanthanoid metal ions for ability to stimulate pro-fibrotic responses in human dermal fibroblasts. When fibroblasts were exposed to individual lanthanoids over the concentration range of 1–100 μM, increased proliferation was observed with each of the agents as compared with control cells that were already proliferating rapidly in a growth factor-enriched culture medium. Dose-response differences were observed among the individual metal ions. Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 levels were also increased in response to lanthanoid exposure but type I procollagen production was not. A dose–response relationship between induction of proliferation and increased MMP-1 was observed. Non-lanthanoid transition metal ions (aluminum, copper, cobalt, iron, magnesium, manganese, nickel, and zinc) were examined in the same assays; there was little stimulation with any of these metals. When epidermal keratinocytes were examined in place of dermal fibroblasts, there was no growth stimulation with any of the lanthanoids. Several of the lanthanoid metals inhibited keratinocyte proliferation at higher concentrations (50–100 μM). PMID:21484406

  2. Effect of Coulomb Explosion on Track Formation in Metals Irradiated by Heavy Ions

    SciTech Connect

    Ryazanov, A.I.; Pavlov, S.A.; Metelkin, E.V.; Zhemerev, A.V.

    2005-07-01

    The existing descriptions of the process of track formation in metals bombarded with high-energy heavy ions are usually based on the T-spike model. However, this model fails to explain high temperatures developed in some target materials (e.g., in copper). We present a comparative analysis of track formation in metals under the action of heavy ion bombardment, as described using the Coulomb explosion model and the T-spike model in various modifications. Both models are used to calculate changes in the temperatures of the electron and ion subsystems in the track region in amorphous alloy Fe{sub 85}B{sub 15}) and copper targets bombarded with identical high-energy (E > 1 MeV/nucleon) heavy ions. The results show that the Coulomb explosion model predicts stronger heating of the ion subsystem in the track region (with the possible formation of a melt-through zone) as compared to the T-spike model. The formation of point defects in copper as a result of the ionization losses has been also described using the two models and compared to the available experimental data. The Coulomb explosion model provides for a more adequate description of track formation as compared to the T-spike model.

  3. The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1993-01-01

    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

  4. Ab Initio Calculations Applied to Problems in Metal Ion Chemistry

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry; Arnold, James O. (Technical Monitor)

    1994-01-01

    Electronic structure calculations can provide accurate spectroscopic data (such as molecular structures) vibrational frequencies, binding energies, etc.) that have been very useful in explaining trends in experimental data and in identifying incorrect experimental measurements. In addition, ab initio calculations. have given considerable insight into the many interactions that make the chemistry of transition metal systems so diverse. In this review we focus on cases where calculations and experiment have been used to solve interesting chemical problems involving metal ions. The examples include cases where theory was used to differentiate between disparate experimental values and cases where theory was used to explain unexpected experimental results.

  5. The corrosion protection of metals by ion vapor deposited aluminum

    SciTech Connect

    Danford, M.D.

    1993-10-01

    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

  6. A comparative study of the structure and cytotoxicity of polytetrafluoroethylene after ion etching and ion implantation

    NASA Astrophysics Data System (ADS)

    Shtansky, D. V.; Glushankova, N. A.; Kiryukhantsev-Korneev, F. V.; Sheveiko, A. N.; Sigarev, A. A.

    2011-03-01

    The ion-plasma treatment has been widely used for modifying the surface structure of polymers in order to improve their properties, but it can lead to destruction of the surface and, as a consequence, to an increase in their toxicity. A comparative study of the structure and cytotoxicity of polytetrafluoroethylene (PTFE) after the ion etching (IE) and ion implantation (II) for 10 min with energy densities of 363 and 226 J/cm2, respectively, has been performed. It has been shown that, unlike the ion implantation, the ion etching results in the destruction of the polymer and in the appearance of the cytotoxicity. The factors responsible for this effect, which are associated with the bulk and surface treatment, as well as with the influence of the temperature, have been discussed.

  7. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrationsin an urban estuary

    EPA Science Inventory

    Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limite...

  8. Production of intense metal ion beams from ECR ion sources using the MIVOC method

    NASA Astrophysics Data System (ADS)

    Bogomolov, S. L.; Bondarchenko, A. E.; Efremov, A. A.; Kuzmenkov, K. I.; Lebedev, A. N.; Lebedev, K. V.; Lebedev, V. Ya.; Loginov, V. N.; Mironov, V. E.; Yazvitsky, N. Yu.

    2015-12-01

    The production of metal ion beams by electron cyclotron resonance (ECR) ion sources using the MIVOC (Metal Ions from Volatile Compounds) method is described. The method is based on the use of metal compounds which have high vapor pressure at room temperature, e.g., C2B10H12, Fe(C5H5)2, etc. Intense ion beams of B and Fe were produced using this method at the FLNR JINR cyclotrons. Experiments on the production of cobalt, chromium, vanadium, germanium, and hafnium ion beams were performed at the test bench of ECR ion sources. Main efforts were put into production and acceleration of 50Ti ion beams at the U-400 cyclotron. The experiments on the production of 50Ti ion beams were performed at the test bench using natural and enriched compounds of titanium (CH3)5C5Ti(CH3)3. In these experiments, 80 μA 48Ti5+ and 70 μA 48Ti11+ beam currents were obtained at different settings of the source. Following successful tests, two 3-week runs were performed with 50Ti beams at the U-400 cyclotron aimed to perform experiments on the spectroscopy of superheavy elements. The intensity of the injected 50Ti5+ beam was 50-60 μA. The source worked stably during experiments. The compound consumption rate was determined at about 2.4 mg/h, which corresponded to the 50Ti consumption of 0.6 mg/h.

  9. Photoelectric properties in metal ion modified DNA nanostructure.

    PubMed

    Kulkarni, Atul; Dugasani, Sreekantha Reddy; Jang Ah Kim; Kim; Sung Ha Park; Taesung Kim

    2015-08-01

    Due to specific or as designed self-assembly, DNA nanostructures gaining popularity in various nanoscale electronic applications. Herein, a novel divalent metal ion-DNA complex known as M-DNA have been investigated for its photoelectric characteristics. The increased conductivity of M-DNA thin films is attributed to the metal ion electrical and optical properties. The gate voltage effect along with illumination on the conductivity of M-DNA demonstrates that M-DNA can be used as an active element of a field-effect transistor. The Zn DNA shows maximum conductivity of 300μS/cm at 480 nm light illumination suggest that M-DNA can be utilized in nano-opto-electronics and bio-sensing applications. PMID:26737260

  10. Nanomagnetic chelators for removal of toxic metal ions

    NASA Astrophysics Data System (ADS)

    Singh, Sarika; Barick, K. C.; Bahadur, D.

    2013-02-01

    Ethylenediamine trtraaceteic acid (EDTA) functionalized Fe3O4 nanomagnetic chelators (NMCs) were synthesized by co-precipitation method followed by in-situ grafting of EDTA. XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. Surface functionalization of Fe3O4 with EDTA was evident from FTIR spectroscopy, TGA analysis and zeta-potential measurement. These NMCs exhibit superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. It has been observed that NMCs have strong tendency for adsorption of various toxic metal ions (Ni2+, Cr3+, Cu2+, Cd2+, Co2+ and Pb2+) from waste-water. Furthermore, these magnetic chelators can be used as highly efficient separable and reusable material for removal of toxic metal ions.

  11. Chelating Agents and the Regulation of Metal Ions

    PubMed Central

    Bulman, Robert A.

    1994-01-01

    Up to about the early 1980s it was perhaps still possible to summarize in a review of a moderate length the development of the medicinal applications of chelation chemistry and the exploitation of such chemistry in regulating the metal ion concentrations in the body. However, in the last few years there has a great surge in the development of chelation chemistry and its usage in medicine and related areas of life sciences research. It is no longer the case that such a review primarily concentrates upon the use of chelating agents in removing toxic metals from the body but it must now cover the use of chelating agents in the imaging procedures nuclear medicine and magnetic resonance imaging (MRI), the use of chelating agents in unravelling the biochemistry of reactive oxidative species (ROS) and the control and measurement of intracellular calcium ions. It is in the recent applications that there have been the greatest developments over the last ten years. PMID:18476223

  12. Selective extraction of metal ions with polymeric extractants by ion exchange/redox

    DOEpatents

    Alexandratos, Spiro D.

    1987-01-01

    The specification discloses a method for the extraction of metal ions having a reduction potential of above about +0.3 from an aqueous solution. The method includes contacting the aqueous solution with a polymeric extractant having primary phosphinic acid groups, secondary phosphine oxide groups, or both phosphinic acid and phosphine oxide groups.

  13. Further studies of ion mixing in binary metal systems

    NASA Astrophysics Data System (ADS)

    Liu, Bai-Xin

    1985-03-01

    Using free energy-composition diagram, a simple model is proposed for the formation of amorphous alloys by ion mixing of metal layers. The basis of the model is the limited atomic mobility in such samples after ion mixing at a suitably low temperature. The model explains the formation of amorphous alloys that have been reported previously and those obtained in this study in the Zr-Ru and Ti-Au systems by ion mixing. These include phases with compositions in both two-phase and single-phase regions of the equilibrium phase diagram. In the Ni-Mo system, an unusual phase transition was observed by X-ray diffraction photos, i.e. an amorphous phase was formed after room temperature aging of an ion induced metastable crystalline phase (h.c.p. structure). Post-irradiation annealing of some ion mixed Ni-Mo amorphous alloys were performed at various temperatures. A schematic free energy diagram is proposed according to the phase evolution in the annealed samples upon annealing, and is used to discuss the ion induced phenomena in this system.

  14. Interaction of heavy metal ions with ammonium humates

    SciTech Connect

    Budaeva, A.D.; Zoltoev, E.V.; Tikhova, V.D.; Bodoev, N.V.

    2006-06-15

    Sorption properties of ammonium humates with respect to Fe(III), Cu(II), Al(III), Ni(II), Pb(II), and Zn(II) are studied. The effect of the metal ion concentration on the ammonium humate consumption is examined and the corresponding dependences are analyzed using regression equations. The IR spectra of brown coal humic acids, ammonium humates, as well as Fe, Cu, Ni, Zn, Pb, and Al humates are presented.

  15. Precious metal catalysts with oxygen-ion conducting support

    SciTech Connect

    Ganguli, P.S.; Sundaresan, S.

    1993-08-03

    A three-way supported catalyst is described for treatment of combustion gas emissions from mobile or stationary sources, comprising: an oxygen-ion conducting support material having surface area at least about 20 m[sup 2]/gm, and two active metals selected from the group consisting of (1) platinum and rhodium and (2) palladium and rhodium dispersed on the support material in overall amount of about 0.01-2.2 wt. % of the catalyst.

  16. Positive ions of the first- and second-row transition metal hydrides

    NASA Technical Reports Server (NTRS)

    Pettersson, Lars G. M.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

    1987-01-01

    Theoretical dissociation energies for the first- and second-row transition metal hydride positive ions are critically compared against recent experimental values obtained from ion beam reactive scattering methods. Theoretical spectroscopic parameters and dipole moments are presented for the ground and several low-lying excited states. The calculations employ large Gaussian basis sets and account for electron correlation using the single-reference single- and double-excitation configuration interaction and coupled-pair-functional methods. The Darwin and mass-velocity contributions to the relativistic energy are included in the all-electron calculations on the first-row systems using first-order perturbation theory, and in the second-row systems using the Hay and Wadt relativistic effective core potentials. The theoretical D(0) values for the second-row transition metal hydride positive ions should provide a critical measure of the experimental values, which are not as refined as many of those in the first transition row.

  17. NOVEL APPROACH TO METAL-HUMIC COMPLEXATION STUDIES BY LANTHANID ION PROBE SPECTROSCOPY

    EPA Science Inventory

    Naturally occurring humic substances are known to be potentially strong binders of metals in the environment. ensitive spectroscopic technique, based on the unique luminescence properties of the tripositive lanthanide metal ions, has been developed to selectively probe metal bind...

  18. CMOS-compatible metal-stabilized nanostructured Si as anodes for lithium-ion microbatteries.

    PubMed

    Lee, Gibaek; Schweizer, Stefan L; Wehrspohn, Ralf B

    2014-01-01

    The properties of fully complementary metal-oxide semiconductor (CMOS)-compatible metal-coated nanostructured silicon anodes for Li-ion microbatteries have been studied. The one-dimensional nanowires on black silicon (nb-Si) were prepared by inductively coupled plasma (ICP) etching and the metal (Au and Cu) coatings by successive magnetron sputtering technique. The Cu-coated nb-Si show the most promising electrochemical performance enhancements for the initial specific capacity as well as their cyclability compared to pristine nb-Si. The electrochemical and microstructural properties before and after cycling of the metal-coated nb-Si compared to their pristine counterparts are discussed in detail. PMID:25411568

  19. Superhydrogels of nanotubes capable of capturing heavy-metal ions.

    PubMed

    Song, Shasha; Wang, Haiqiao; Song, Aixin; Hao, Jingcheng

    2014-01-01

    Self-assembly regulated by hydrogen bonds was successfully achieved in the system of lithocholic acid (LCA) mixed with three organic amines, ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA), in aqueous solutions. The mixtures of DEA/LCA exhibit supergelation capability and the hydrogels consist of plenty of network nanotubes with uniform diameters of about 60 nm determined by cryogenic TEM. Interestingly, the sample with the same concentration in a system of EA and LCA is a birefringent solution, in which spherical vesicles and can be transformed into nanotubes as the amount of LCA increases. The formation of hydrogels could be driven by the delicate balance of diverse noncovalent interactions, including electrostatic interactions, hydrophobic interactions, steric effects, van der Waals forces, and mainly hydrogen bonds. The mechanism of self-assembly from spherical bilayer vesicles into nanotubes was proposed. The dried hydrogels with nanotubes were explored to exhibit the excellent capability for capturing heavy-metal ions, for example, Cu(2+), Co(2+), Ni(2+), Pb(2+), and Hg(2+). The superhydrogels of nanotubes from the self-assembly of low-molecular-weight gelators mainly regulated by hydrogen bonds used for the removal of heavy-metal ions is simple, green, and high efficiency, and provide a strategic approach to removing heavy-metal ions from industrial sewage. PMID:24136830

  20. Age and Smoking Related Changes in Metal Ion Levels in Human Lens: Implications for Cataract Formation

    PubMed Central

    Langford-Smith, Alex; Tilakaratna, Viranga; Lythgoe, Paul R.; Clark, Simon J.; Bishop, Paul N.; Day, Anthony J.

    2016-01-01

    Age-related cataract formation is the primary cause of blindness worldwide and although treatable by surgical removal of the lens the majority of sufferers have neither the finances nor access to the medical facilities required. Therefore, a better understanding of the pathogenesis of cataract may identify new therapeutic targets to prevent or slow its progression. Cataract incidence is strongly correlated with age and cigarette smoking, factors that are often associated with accumulation of metal ions in other tissues. Therefore this study evaluated the age-related changes in 14 metal ions in 32 post mortem human lenses without known cataract from donors of 11 to 82 years of age by inductively coupled plasma mass spectrometry; smoking-related changes in 10 smokers verses 14 non-smokers were also analysed. A significant age-related increase in selenium and decrease in copper ions was observed for the first time in the lens tissue, where cadmium ion levels were also increased as has been seen previously. Aluminium and vanadium ions were found to be increased in smokers compared to non-smokers (an analysis that has only been carried out before in lenses with cataract). These changes in metal ions, i.e. that occur as a consequence of normal ageing and of smoking, could contribute to cataract formation via induction of oxidative stress pathways, modulation of extracellular matrix structure/function and cellular toxicity. Thus, this study has identified novel changes in metal ions in human lens that could potentially drive the pathology of cataract formation. PMID:26794210

  1. Density Functional Theory Study on the Interactions of Metal Ions with Long Chain Deprotonated Carboxylic Acids.

    PubMed

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Koch, Henrik; Åstrand, Per-Olof; Trinh, Thuat T; Grimes, Brian A

    2015-10-01

    In this work, interactions between carboxylate ions and calcium or sodium ions are investigated via density functional theory (DFT). Despite the ubiquitous presence of these interactions in natural and industrial chemical processes, few DFT studies on these systems exist in the literature. Special focus has been placed on determining the influence of the multibody interactions (with up to 4 carboxylates and one metal ion) on an effective pair-interaction potential, such as those used in molecular mechanics (MM). Specifically, DFT calculations are employed to quantify an effective pair-potential that implicitly includes multibody interactions to construct potential energy curves for carboxylate-metal ion pairs. The DFT calculated potential curves are compared to a widely used molecular mechanics force field (OPLS-AA). The calculations indicate that multibody effects do influence the energetic behavior of these ionic pairs and the extent of this influence is determined by a balance between (a) charge transfer from the carboxylate to the metal ions which stabilizes the complex and (b) repulsion between carboxylates, which destabilizes the complex. Additionally, the potential curves of the complexes with 1 and 2 carboxylates and one counterion have been examined to higher separation distance (20 Å) by the use of relaxed scan optimization and constrained density functional theory (CDFT). The results from the relaxed scan optimization indicate that near the equilibrium distance, the charge transfer between the metal ion and the deprotonated carboxylic acid group is significant and leads to non-negligible differences between the DFT and MM potential curves, especially for calcium. However, at longer separation distances the MM calculated interaction potential functions converge to those calculated with CDFT, effectively indicating the approximate domain of the separation distance coordinate where charge transfer between the ions is occurring. PMID:26331433

  2. Nanostructure operations by means of the liquid metal ion sourcesa)

    NASA Astrophysics Data System (ADS)

    Gasanov, I. S.; Gurbanov, I. I.

    2012-02-01

    Characteristics of a disperse phase of liquid metal ion source on the basis of various working substances are investigated. It is revealed that generation of the charged particles occurs in the threshold image and is simultaneously accompanied by excitation of capillary instability on a surface of the emitter. The majority of particles has the size about 2 nm (Sn) and a specific charge of 5 × 104 C/kg. If the working liquid possesses high viscosity (Ni), generation of nanodroplets does not occur. Gold nanoparticles are used for deposition on a surface of quartz cantilevers with the purpose of increase in sensitivity of biosensors and on an external surface of carbon nanotubes for creation pressure sensors. By means of an ion source nanostructures can be etched on a flat surface of conductive materials without difficult ion optics.

  3. Regulated incorporation of two different metal ions into programmed sites in a duplex by DNA polymerase catalyzed primer extension.

    PubMed

    Funai, Tatsuya; Nakamura, Junko; Miyazaki, Yuki; Kiriu, Risa; Nakagawa, Osamu; Wada, Shun-ichi; Ono, Akira; Urata, Hidehito

    2014-06-23

    Metal-mediated base pairs formed by the coordination of metal ions to natural or artificial bases impart unique chemical and physical properties to nucleic acids and have attracted considerable interest in the field of nanodevices. Ag(I) ions were found to mediate DNA polymerase catalyzed primer extension through the formation of a C-Ag(I)-T base pair, as well as the previously reported C-Ag(I)-A base pair. The comparative susceptibility of dNTPs to Ag(I)-mediated enzymatic incorporation into the site opposite cytosine in the template was shown to be dATP>dTTP≫dCTP. Furthermore, two kinds of metal ions, Ag(I) and Hg(II), selectively mediate the incorporation of thymidine 5'-triphosphate into sites opposite cytosine and thymine in the template, respectively. In other words, the regulated incorporation of different metal ions into programmed sites in the duplex by DNA polymerase was successfully achieved. PMID:24719384

  4. Adsorption of heavy metal ions by immobilized phytic acid

    SciTech Connect

    Tsao, G.T.; Zheng, Yizhou; Lu, J.; Gong, Cheng S.

    1997-12-31

    Phytic acid (myoinositol hexaphosphate) or its calcium salt, phytate, is an important plant constituents. It accounts for up to 85% of total phosphorus in cereals and legumes. Phytic acid has 12 replaceable protons in the phytic molecule rendering it the ability to complex with multivalent cations and positively charged proteins. Poly 4-vinyl pyridine (PVP) and other strong-based resins have the ability to adsorb phytic acid. PVP has the highest adsorption capacity of 0.51 phytic acid/resins. The PVP resin was used as the support material for the immobilization of phytic acid. The immobilized phytic acid can adsorb heavy metal ions, such as cadmium, copper, lead, nickel, and zinc ions, from aqueous solutions. Adsorption isotherms of the selected ions by immobilized phytic acid were conducted in packed-bed column at room temperature. Results from the adsorption tests showed 6.6 mg of Cd{sup 2+}, 7 mg of Cu{sup 2+}, 7.2 mg of Ni{sup 2+}, 7.4 mg of Pb{sup 2+}, and 7.7 mg of Zn{sup 2+} can be adsorbed by each gram of PVP-phytic acid complex. The use of immobilized phytic acid has the potential for removing metal ions from industrial or mining waste water. 15 refs., 7 figs., 2 tabs.

  5. Template-directed synthesis of oligoguanylic acids - Metal ion catalysis

    NASA Technical Reports Server (NTRS)

    Bridson, P. K.; Fakhrai, H.; Lohrmann, R.; Orgel, L. E.; Van Roode, M.

    1981-01-01

    The effects of Zn(2+), Pb(2+) and other metal ions on the efficiency and stereo-selectivity of the template-directed oligomerization of guanosine 5'-phosphorimidazolide are investigated. Reactions were run in the presence of a polyC template in a 2,6-lutidine buffer, and products analyzed by high-performance liquid chromatography on an RPC-5 column. The presence of the Pb(2+) ion is found to lead to the formation of 2'-5' linked oligomers up to the 40-mer, while Zn(2+) favors the formation of predominantly 3'-5' linked oligomers up to the 35-mer. When amounts of uracil, cytidine or adenosine 5'-phosphorimidazole equal to those of the guanosine derivative are included in the reaction mixture, the incorrect base is incorporated into the oligomer about 10% of the time with a Pb(2+) catalyst, but less than 0.5% of the time with Zn(2+). The Sn(2+), Sb(3+) and Bi(3+) ions are also found to promote the formation of 2'-5' oligomers, although not as effectively as Pb(2+), while no metal ions other than Zn(2+) promote the formation of the 3'-5' oligomers. The results may be important for the understanding of the evolution of nucleic acid replication in the absence of enzymes.

  6. Note: An ion source for alkali metal implantation beneath graphene and hexagonal boron nitride monolayers on transition metals

    NASA Astrophysics Data System (ADS)

    de Lima, L. H.; Cun, H. Y.; Hemmi, A.; Kälin, T.; Greber, T.

    2013-12-01

    The construction of an alkali-metal ion source is presented. It allows the acceleration of rubidium ions to an energy that enables the penetration through monolayers of graphene and hexagonal boron nitride. Rb atoms are sublimated from an alkali-metal dispenser. The ionization is obtained by surface ionization and desorption from a hot high work function surface. The ion current is easily controlled by the temperature of ionizer. Scanning Tunneling Microscopy measurements confirm ion implantation.

  7. Note: An ion source for alkali metal implantation beneath graphene and hexagonal boron nitride monolayers on transition metals

    SciTech Connect

    Lima, L. H. de; Cun, H. Y.; Hemmi, A.; Kälin, T.; Greber, T.

    2013-12-15

    The construction of an alkali-metal ion source is presented. It allows the acceleration of rubidium ions to an energy that enables the penetration through monolayers of graphene and hexagonal boron nitride. Rb atoms are sublimated from an alkali-metal dispenser. The ionization is obtained by surface ionization and desorption from a hot high work function surface. The ion current is easily controlled by the temperature of ionizer. Scanning Tunneling Microscopy measurements confirm ion implantation.

  8. Molecular designs for controlling the local environments around metal ions.

    PubMed

    Cook, Sarah A; Borovik, A S

    2015-08-18

    -oxyl radical. We therefore probed the amount of spin density on the oxido ligand of our complexes using EPR spectroscopy in conjunction with oxygen-17 labeling. Our findings showed that there is a significant amount of spin on the oxido ligand, yet the M-oxo bonds are best described as highly covalent and there is no indication that an oxyl radical is formed. These results offer the intriguing possibility that high-spin M-oxo complexes are involved in O-O bond formation in biology. Ligand redesign to incorporate H-bond accepting units (sulfonamido groups) simultaneously provided a metal ion binding pocket, adjacent H-bond acceptors, and an auxiliary binding site for a second metal ion. These properties allowed us to isolate a series of heterobimetallic complexes of Fe(III) and Mn(III) in which a group II metal ion was coordinated within the secondary coordination sphere. Examination of the influence of the second metal ion on the electron transfer properties of the primary metal center revealed unexpected similarities between Ca(II) and Sr(II) ions, a result with relevance to the OEC. In addition, the presence of a second metal ion was found to prevent intramolecular oxidation of the ligand with an O atom transfer reagent. PMID:26181849

  9. Recovery of toxic metal ions from washing effluent containing excess aminopolycarboxylate chelant in solution.

    PubMed

    Hasegawa, Hiroshi; Rahman, Ismail M M; Nakano, Masayoshi; Begum, Zinnat A; Egawa, Yuji; Maki, Teruya; Furusho, Yoshiaki; Mizutani, Satoshi

    2011-10-15

    Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatment of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2 mL min(-1). The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants

  10. Calcium Inhibition of Ribonuclease H1 Two-Metal Ion Catalysis

    PubMed Central

    2015-01-01

    Most phosphate-processing enzymes require Mg2+ as a cofactor to catalyze nucleotide cleavage and transfer reactions. Ca2+ ions inhibit many of these enzymatic activities, despite Ca2+ and Mg2+ having comparable binding affinities and overall biological abundances. Here we study the molecular details of the calcium inhibition mechanism for phosphodiester cleavage, an essential reaction in the metabolism of nucleic acids and nucleotides, by comparing Ca2+- and Mg2+ catalyzed reactions. We study the functional roles of the specific metal ion sites A and B in enabling the catalytic cleavage of an RNA/DNA hybrid substrate by B. halodurans ribonuclease (RNase) H1 using hybrid quantum-mechanics/molecular mechanics (QM/MM) free energy calculations. We find that Ca2+ substitution of either of the two active-site Mg2+ ions substantially increases the height of the reaction barrier and thereby abolishes the catalytic activity. Remarkably, Ca2+ at the A site is inactive also in Mg2+-optimized active-site structures along the reaction path, whereas Mg2+ substitution recovers activity in Ca2+-optimized structures. Geometric changes resulting from Ca2+ substitution at metal ion site A may thus be a secondary factor in the loss of catalytic activity. By contrast, at metal ion site B geometry plays a more important role, with only a partial recovery of activity after Mg2+ substitution in Ca2+-optimized structures. Ca2+-substitution also leads to a change in mechanism, with deprotonation of the water nucleophile requiring a closer approach to the scissile phosphate, which in turn increases the barrier. As a result, Ca2+ is less efficient in activating the water. As a likely cause for the different reactivities of Mg2+ and Ca2+ ions in site A, we identify differences in charge transfer to the ions and the associated decrease in the pKa of the oxygen nucleophile attacking the phosphate group. PMID:24499076

  11. Calcium inhibition of ribonuclease H1 two-metal ion catalysis.

    PubMed

    Rosta, Edina; Yang, Wei; Hummer, Gerhard

    2014-02-26

    Most phosphate-processing enzymes require Mg(2+) as a cofactor to catalyze nucleotide cleavage and transfer reactions. Ca(2+) ions inhibit many of these enzymatic activities, despite Ca(2+) and Mg(2+) having comparable binding affinities and overall biological abundances. Here we study the molecular details of the calcium inhibition mechanism for phosphodiester cleavage, an essential reaction in the metabolism of nucleic acids and nucleotides, by comparing Ca(2+)- and Mg(2+) catalyzed reactions. We study the functional roles of the specific metal ion sites A and B in enabling the catalytic cleavage of an RNA/DNA hybrid substrate by B. halodurans ribonuclease (RNase) H1 using hybrid quantum-mechanics/molecular mechanics (QM/MM) free energy calculations. We find that Ca(2+) substitution of either of the two active-site Mg(2+) ions substantially increases the height of the reaction barrier and thereby abolishes the catalytic activity. Remarkably, Ca(2+) at the A site is inactive also in Mg(2+)-optimized active-site structures along the reaction path, whereas Mg(2+) substitution recovers activity in Ca(2+)-optimized structures. Geometric changes resulting from Ca(2+) substitution at metal ion site A may thus be a secondary factor in the loss of catalytic activity. By contrast, at metal ion site B geometry plays a more important role, with only a partial recovery of activity after Mg(2+) substitution in Ca(2+)-optimized structures. Ca(2+)-substitution also leads to a change in mechanism, with deprotonation of the water nucleophile requiring a closer approach to the scissile phosphate, which in turn increases the barrier. As a result, Ca(2+) is less efficient in activating the water. As a likely cause for the different reactivities of Mg(2+) and Ca(2+) ions in site A, we identify differences in charge transfer to the ions and the associated decrease in the pKa of the oxygen nucleophile attacking the phosphate group. PMID:24499076

  12. Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology

    SciTech Connect

    Lentz, Nicholas B.

    2007-01-01

    This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was found that instrument interface design also plays a critical role in the cluster ion distribution seen in the mass spectrum. In Chapter 5, ESI-MS was used to investigate toxic metal binding to the [Gln11]-amyloid β-protein fragment (1-16). Pb and Cd bound stronger than Zn, even in the presence of excess Zn. Hg bound weaker than Zn. There are endless options for future work on cluster ions. Any molecule that is poorly ionized in positive ion mode can potentially show an increase in ionization efficiency if an appropriate anion is used to produce a net negative charge. It is possible that drug protein or drug/DNA complexes can also be stabilized by adding counter-ions. This would preserve the solution characteristics of the complex in the gas phase. Once in the gas phase, CID could determine the drug binding location on the biomolecule. There are many research projects regarding toxic metals in biology that have yet to be investigated or even discovered. This is an area of research with an almost endless future because of the changing dynamics of biological systems. What is deemed safe today may show toxic effects in the future. Evolutionary changes in protein structures may render them more susceptible to toxic metal binding. As the understanding of toxicity evolves, so does the demand for new toxic metal research. New instrumentation designs and software make it possible to perform research that could not be done in the past. What was undetectable yesterday will

  13. Comparison of Whole-Blood Metal Ion Levels Among Four Types of Large-Head, Metal-on-Metal Total Hip Arthroplasty Implants: A Concise Follow-up, at Five Years, of a Previous Report.

    PubMed

    Hutt, Jonathan; Lavigne, Martin; Lungu, Eugen; Belzile, Etienne; Morin, François; Vendittoli, Pascal-André

    2016-02-17

    Few studies of total hip arthroplasty (THA) implants with a large-diameter femoral head and metal-on-metal design have directly compared the progression of metal ion levels over time and the relationship to complications. As we previously reported, 144 patients received one of four types of large-diameter-head, metal-on-metal THA designs (Durom, Birmingham, ASR XL, or Magnum implants). Cobalt, chromium, and titanium ion levels were measured over five years. We compared ion levels and clinical results over time. The Durom group showed the highest levels of cobalt (p ≤ 0.002) and titanium ions (p ≤ 0.03). Both the Durom and Birmingham groups demonstrated significant ongoing cobalt increases up to five years. Eight patients (seven with a Durom implant and one with a Birmingham implant) developed adverse local tissue reaction. Six Durom implants and one Birmingham implant required revision, with one pseudotumor under surveillance at the time of the most recent follow-up. We found that ion generation and related complications varied among designs. More concerning was that, for some designs, ion levels continued to increase. Coupling a cobalt-chromium adapter sleeve to an unmodified titanium femoral trunnion along with a large metal-on-metal bearing may explain the poor performances of two of the designs in the current study. PMID:26888673

  14. Two distinct modes of metal ion binding in the nuclease active site of a viral DNA-packaging terminase: insight into the two-metal-ion catalytic mechanism

    PubMed Central

    Zhao, Haiyan; Lin, Zihan; Lynn, Anna Y.; Varnado, Brittany; Beutler, John A.; Murelli, Ryan P.; Le Grice, Stuart F. J.; Tang, Liang

    2015-01-01

    Many dsDNA viruses encode DNA-packaging terminases, each containing a nuclease domain that resolves concatemeric DNA into genome-length units. Terminase nucleases resemble the RNase H-superfamily nucleotidyltransferases in folds, and share a two-metal-ion catalytic mechanism. Here we show that residue K428 of a bacteriophage terminase gp2 nuclease domain mediates binding of the metal cofactor Mg2+. A K428A mutation allows visualization, at high resolution, of a metal ion binding mode with a coupled-octahedral configuration at the active site, exhibiting an unusually short metal-metal distance of 2.42 Å. Such proximity of the two metal ions may play an essential role in catalysis by generating a highly positive electrostatic niche to enable formation of the negatively charged pentacovalent phosphate transition state, and provides the structural basis for distinguishing Mg2+ from Ca2+. Using a metal ion chelator β-thujaplicinol as a molecular probe, we observed a second mode of metal ion binding at the active site, mimicking the DNA binding state. Arrangement of the active site residues differs drastically from those in RNase H-like nucleases, suggesting a drifting of the active site configuration during evolution. The two distinct metal ion binding modes unveiled mechanistic details of the two-metal-ion catalysis at atomic resolution. PMID:26450964

  15. Luminescent zinc metal-organic framework (ZIF-90) for sensing metal ions, anions and small molecules.

    PubMed

    Liu, Chang; Yan, Bing

    2015-09-26

    We synthesize a zinc zeolite-type metal-organic framework, the zeolitic imidazolate framework (ZIF-90), which exhibits an intense blue luminescence excited under visible light. Luminescent studies indicate that ZIF-90 could be an efficient multifunctional fluorescence material for high sensitivity metal ions, anions and organic small molecules, especially for Cd(2+), Cu(2+), CrO4(2-) and acetone. The luminescence intensity of ZIF-90 increases with the concentration of Cd(2+) and decreases proportionally with the concentration of Cu(2+), while the same quenched experimental phenomena appear in the sensing of CrO4(2-). With the increase of the amount of acetone, the luminescence intensity decreases gradually in the emulsions of ZIF-90. The mechanism of the sensing properties is studied in detail as well. This study shows that ZIF-90 could be a useful luminescent sensor for metal ions, anions and organic small molecules. PMID:26123790

  16. Radiation damage from single heavy ion impacts on metal surfaces

    SciTech Connect

    Donnelly, S.E.; Birtcher, R.C.

    1998-06-01

    The effects of single ion impacts on the surfaces of films of Au, Ag, In and Pb have been studied using in-situ transmission electron microscopy. On all of these materials, individual ion impacts produce surface craters, in some cases, with associated expelled material. The cratering efficiency scales with the density of the irradiated metal. For very thin Au foils ({approx} 20--50 nm), in some cases individual ions are seen to punch small holes completely through the foil. Continued irradiation results in a thickening of the foil. The process giving rise to crater and hole formation and other changes observed in the thin foils has been found to be due to pulsed localized flow--i.e. melting and flow due to the thermal spikes arising from individual ion impacts. Experiments carried out on thin films of silver sandwiched between SiO{sub 2} layers have indicated that pulsed localized flow also occurs in this system and contributes to the formation of Ag nanoclusters in SiO{sub 2}--a system of interest for its non-linear optical properties. Calculation indicates that, when ion-induced, collision cascades occur near surfaces (within {approx} 5 nm) with energy densities sufficient to cause melting, craters are formed. Crater formation occurs as a result of the explosive outflow of material from the hot molten core of the cascade. Processes occurring in the sandwiched layer are less well understood.

  17. Phase and structural transformations in metallic iron under the action of heavy ions and recoil nuclei.

    PubMed

    Alekseev, I; Novikov, D

    2014-02-01

    By the use of various modes of Mössbauer spectroscopy after effects of irradiation of metal iron with (12)C(4+) and (14)N(5+) ions of medium energies, and alpha-particles and the (208)Tl, (208,212)Pb, and (216)Po recoil from a (228)Th-source have been studied. The experimental data obtained in the study enabled various types of external and internal radiation to be compared in regard to the damage they cause, as well as to their effect on the structure-, phase composition- and corrosion resistance properties of metallic iron. Irradiation with (12)C(4+) and (14)N(5+) ions is accompanied by both structural disordering of the α-Fe lattice, and the appearance of γ-phase in the bulk metal. This is indicated by a single line which is 2 to 3-fold broadened (as compared to the lines of the magnetic sextet). This is a result of a strong local heating of the lattice in the thermal spike area with a subsequent instant cooling-down and recrystallization of this "molted" area. Irradiation of iron foils with (12)C(4+)- and (14)N(5+) ions and with recoil nuclei does provoke corrosion processes (the formation of γ-FeOOH) and is accompanied by an intensive oxidation of the metal. PMID:24378918

  18. A comparative study of metal contamination in soil using the borehole method.

    PubMed

    Teh, T L; Rahman, Nik Norulaini Nik Ab; Shahadat, Mohammad; Wong, Y S; Syakir, Muhammad I; Omar, A K Mohd

    2016-07-01

    The present study deals with possible contamination of the soil by metal ions which have been affecting the environment. The concentrations of metal ions in 14 borehole samples were studied using the ICP-OES standard method. The degree of contamination was determined on the basis of single element pollution index (SEPI), combined pollution index (CPI), soil enrichment factor (SEF), and geo-accumulation index (Igeo). Geo-accumulation indices and contamination factors indicated moderate to strong contaminations for eight boreholes (BL-1, BL-2, BL-6, BL-8, BL-9, BL-10, BL-12, and BL-13) while the rest were extremely contaminated. Among all the boreholes, BL-3 and BL-11 demonstrated the highest level of Cd(II) and Pb(II) which were found the most polluted sites. The level of metal contamination was also compared with other countries. The development, variation, and limitations regarding the regulations of soil and groundwater contamination can be provided as a helpful guidance for the risk assessment of metal ions in developing countries. PMID:27295186

  19. Cobalt activation of Escherichia coli 5'-nucleotidase is due to zinc ion displacement at only one of two metal-ion-binding sites.

    PubMed Central

    McMillen, Lyle; Beacham, Ifor R; Burns, Dennis M

    2003-01-01

    Escherichia coli 5'-nucleotidase activity is stimulated 30- to 50-fold in vitro by the addition of Co(2+). Seven residues from conserved sequence motifs implicated in the catalytic and metal-ion-binding sites of E. coli 5'-nucleotidase (Asp(41), His(43), Asp(84), His(117), Glu(118), His(217) and His(252)) were selected for modification using site-directed mutagenesis of the cloned ushA gene. On the basis of comparative studies between the resultant mutant proteins and the wild-type enzyme, a model is proposed for E. coli 5'-nucleotidase in which a Co(2+) ion may displace the Zn(2+) ion at only one of two metal-ion-binding sites; the other metal-ion-binding site retains the Zn(2+) ion already present. The studies reported herein suggest that displacement occurs at the metal-ion-binding site consisting of residues Asp(84), Asn(116), His(217) and His(252), leading to the observed increase in 5'-nucleotidase activity. PMID:12603203

  20. The influence of metal artefacts on the range of ion beams

    NASA Astrophysics Data System (ADS)

    Jäkel, Oliver; Reiss, Petra

    2007-02-01

    The influence of artefacts due to metal implants on the range of ion beams is investigated, using a geometrically well-defined head and pelvic phantom together with inserts from steel, titanium and tungsten. The ranges along various beam paths including artefacts were calculated from the TPS and compared to known calculations for phantoms without any insert. In the head phantom, beams intersecting the streak artefacts lead to errors in the range of around or below 1%, which is mainly due to a cancellation of various effects. Beams through the metal or close to it show an underestimation of 3.5% of the range for tungsten. For the pelvic phantom, a large underestimation of the range is observed for a lateral path through the metal insert. In the case of tungsten and steel, range errors of -5% and -18% are observed, respectively. Such beam paths are typically used for pelvic tumours in radiotherapy with ion beams. For beams in the anterior-posterior direction through the inserts, an overestimation of ion ranges of up to 3% for titanium and 8% for steel is expected, respectively. Beam paths outside the metal insert show a large cancellation for the lateral beams (leading to errors of around 1% only) and somewhat higher errors for anterior-posterior beams (around 3% for titanium and 6% for steel). The analysis of CT data of patients with dental implants of gold as compared to patients with healthy teeth also showed a significant effect of the artefacts on the distribution of HU in the data, namely a redistribution of HU to higher and lower values as compared to patients with healthy teeth. The corresponding mean range variation was a 2.5% reduction in the data with artefacts as compared to the data without artefacts. It is concluded that beam paths through metal implants should generally be avoided in proton and ion therapy. In this case, the underestimation of ion range due to artefacts alone may amount to 3% for dental fillings and up to 5% and 18% for hip prosthesis

  1. No association between serum metal ions and implant fixation in large-head metal-on-metal total hip arthroplasty

    PubMed Central

    Søballe, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken

    2014-01-01

    Background The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1–2 and 2–5 years. At 2–5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < –1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation Most cups and stems were well-fixed at 1–5 years. However, at 2–5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the

  2. Dynamics of ions produced by laser ablation of several metals at 193 nm

    SciTech Connect

    Baraldi, G.; Perea, A.; Afonso, C. N.

    2011-02-15

    This work reports the study of ion dynamics produced by ablation of Al, Cu, Ag, Au, and Bi targets using nanosecond laser pulses at 193 nm as a function of the laser fluence from threshold up to 15 J cm{sup -2}. An electrical (Langmuir) probe has been used for determining the ion yield as well as kinetic energy distributions. The results clearly evidence that ablation of Al shows unique features when compared to other metals. The ion yield both at threshold (except for Al, which shows a two-threshold-like behavior) and for a fixed fluence above threshold scale approximately with melting temperature of the metal. Comparison of the magnitude of the yield reported in literature using other wavelengths allows us to conclude its dependence with wavelength is not significant. The evolution of the ion yield with fluence becomes slower for fluences above 4-5 J cm{sup -2} with no indication of saturation suggesting that ionization processes in the plasma are still active up to 15 J cm{sup -2} and production of multiple-charged ions are promoted. This dependence is mirrored in the proportion of ions with kinetic energies higher than 200 eV. This proportion is not significant around threshold fluence for all metals except for Al, which is already 20%. The unique features of Al are discussed in terms of the energy of laser photons (6.4 eV) that is enough to induce direct photoionization from the ground state only in the case of this metal.

  3. Metal ion binding to phospholipid bilayers evaluated by microaffinity chromatography.

    PubMed

    Ross, Eric E; Hoag, Christian; Pfeifer, Zach; Lundeen, Christopher; Owens, Sarah

    2016-06-17

    Group I and II ion binding to phospholipid membranes was evaluated by affinity chromatography utilizing a new stationary phase system based on lipid bilayers supported within large-pore particles composed of Stöber silica spheres. Using an inductively coupled plasma mass spectrometer for detection, robust determination of binding selectivity within group II ions is achieved with capillary columns containing nanomole quantities of lipid and using picomoles of metal analyte. Columns with a unique lipid formulation can be prepared within three hours using a solvent-casting assembly method. The observable thermotropic phase behavior of dipalmitoylphosphatidylcholine has a significant effect on alkaline metal binding and demonstrates the dynamic nature of the supported bilayers. Of the group I ions, only lithium exhibits retention with neutral phosphatidylcholine bilayer stationary phases. A comparison of Stöber-based supports with two commercially available large-pore silicas reveals the effect that particle structure has on analyte accessibility to the bilayer surface as evaluated by retention per supported lipid mass. PMID:27189434

  4. Barcoded materials based on photoluminescent hybrid system of lanthanide ions-doped metal organic framework and silica via ion exchange.

    PubMed

    Shen, Xiang; Yan, Bing

    2016-04-15

    A multicolored photoluminescent hybrid system based on lanthanide ions-doped metal organic frameworks/silica composite host has potential in display and barcode applications. By controlling the stoichiometry of the lanthanides via cation exchange, proportional various lanthanide ions are successfully introduced into metal organic frameworks, whose emission intensity is correspondingly proportional to its amount. The resulting luminescent barcodes depend on the lanthanide ions ratios and compositions. Subsequently, the lanthanide ions located in the channels of metal organic frameworks are protected from any interaction with the environment after the modification of silica on the surface. The optical and thermal stability of the hybrid materials are improved for technological application. PMID:26852345

  5. Expressing a bacterial mercuric ion binding protein in plant for phytoremediation of heavy metals.

    PubMed

    Hsieh, Ju-Liang; Chen, Ching-Yi; Chiu, Meng-Hsuen; Chein, Mei-Fang; Chang, Jo-Shu; Endo, Ginro; Huang, Chieh-Chen

    2009-01-30

    A specific mercuric ion binding protein (MerP) originating from transposon TnMERI1 of Bacillus megaterium strain MB1 isolated from Minamata Bay displayed good adsorption capability for a variety of heavy metals. In this study, the Gram-positive MerP protein was expressed in transgenic Arabidopsis to create a model system for phytoremediation of heavy metals. Under control of an actin promoter, the transgenic Arabidpsis showed higher tolerance and accumulation capacity for mercury, cadium and lead when compared with the control plant. Results from confocal microscopy analysis also indicate that MerP was localized at the cell membrane and vesicles of plant cells. The developed transgenic plants possessing excellent metal-accumulative ability could have potential applications in decontamination of heavy metals. PMID:18538925

  6. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    SciTech Connect

    Lu, Yi

    2002-06-01

    The goals of the project are to develop new catalytic DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides and metal ions, and apply the sensors for on-site, real-time assessment of concentration, speciation and stability of the individual contaminants during and after bioremediation. A negative selection strategy was tested and validated. In vitro selection was shown to yield highly active and specific transition metal ion-dependent catalytic DNA/RNA. A fluorescence resonance energy transfer (FRET) study of in vitro selected DNA demonstrated that the trifluorophore labeled system is a simple and powerful tool in studying complex biomolecules structure and dynamics, and is capable of revealing new sophisticated structural changes. New fluorophore/quenchers in a single fluorosensor yielded improved signal to noise ratio in detection, identification and quantification of metal contaminants. Catalytic DNA fluorescent and colorimetric sensors were shown useful in sensing lead in lake water and in leaded paint. Project results were described in two papers and two patents, and won an international prize.

  7. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    SciTech Connect

    Lu, Yi

    2003-06-01

    The goals of the project are to develop new catalytic DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides and metal ions, and apply the sensors for on-site, real-time assessment of concentration, speciation and stability of the individual contaminants during and after bioremediation. A negative selection strategy was tested and validated. In vitro selection was shown to yield highly active and specific transition metal ion-dependent catalytic DNA/RNA. A fluorescence resonance energy transfer (FRET) study of in vitro selected DNA demonstrated that the trifluorophore labeled system is a simple and powerful tool in studying complex biomolecules structure and dynamics, and is capable of revealing new sophisticated structural changes. New fluorophore/quenchers in a single fluorosensor yielded improved signal to noise ratio in detection, identification and quantification of metal contaminants. Catalytic DNA fluorescent and colorimetric sensors were shown useful in sensing lead in lake water and in leaded paint. Project results were described in two papers and two patents, and won an international prize.

  8. Lanthanide metal-organic frameworks as selective microporous materials for adsorption of heavy metal ions.

    PubMed

    Jamali, Abbas; Tehrani, Alireza Azhdari; Shemirani, Farzaneh; Morsali, Ali

    2016-06-14

    Four microporous lanthanide metal-organic frameworks (MOFs), namely Ln(BTC)(H2O)(DMF)1.1 (Ln = Tb, Dy, Er and Yb, DMF = dimethylformamide, H3BTC = benzene-1,3,5-tricarboxylic acid), have been used for selective adsorption of Pb(ii) and Cu(ii). Among these MOFs, the Dy-based MOF shows better adsorption property and selectivity toward Pb(ii) and Cu(ii) ions. Adsorption isotherms indicate that sorption of Pb(ii) and Cu(ii) on MOFs is via monolayer coverage. Preconcentration is based on solid-phase extraction in which MOFs were rapidly injected into water samples and adsorption of metal ions was rapid because of good contact with analyte; then adsorbed Pb(ii) and Cu(ii) ions were analyzed by FAAS. The optimized methodology represents good linearity between 1 and 120 μg L(-1) and detection limit of 0.4 and 0.26 μg L(-1) for Pb(ii) and Cu(ii), respectively. Subsequently the method was evaluated for preconcentration of target metal ions in some environmental water samples. PMID:27171975

  9. Correlation between the limiting pH of metal ion solubility and total metal concentration

    SciTech Connect

    Apak, R.; Hizal, J.; Ustaer, C.

    1999-03-15

    As an alternative to species distribution diagrams (pM vs pH curves in aqueous solution) drawn for a fixed total metal concentration, this work has developed simple linear models for correlating the limiting pH of metal ion solubility -- in equilibrium with the least soluble amorphous metal hydroxide solid phase -- to the total metal concentration. Thus adsorptive metal removal processes in complex systems can be better designed once the limiting pH of heavy metal solubility (i.e., pH{sup *}) in such a complex environment can be envisaged by simple linear equations. pH{sup *} vs pM{sub t} (M{sub t} = total metal concentration that can exist in aqueous solution in equilibrium with M(OH){sub 2(s)}) linear curves for uranyl-hydroxide, uranyl-carbonate-hydroxide, and mercuric-chloride-hydroxide simple and mixed-ligand systems and cupric-carbonate-hydroxide complexes in equilibrium with mixed hydroxide solid phases may enable the experimental chemist to distinguish true adsorption (e.g., onto hydrous oxide sorbents) from bulk precipitation removal of the metal and to interpret some anomalous metal fixation data -- usually attributed to pure adsorption in the literature -- with precipitation if the pM{sub t} at the studied pH is lower than that tolerated by pH{sup *} vs pM{sub t} curves. This easily predictable pH{sup *} corresponding to a given pM{sub t} may aid the design of desorptive mobilization experiments for certain metals as well as their adsorptive removal with the purpose of simulating metal adsorption and desorption cycles in real complex environments with changing groundwater pH.

  10. The Effect of Complex Formation upon the Redox Potentials of Metallic Ions. Cyclic Voltammetry Experiments.

    ERIC Educational Resources Information Center

    Ibanez, Jorge G.; And Others

    1988-01-01

    Describes experiments in which students prepare in situ soluble complexes of metal ions with different ligands and observe and estimate the change in formal potential that the ion undergoes upon complexation. Discusses student formation and analysis of soluble complexes of two different metal ions with the same ligand. (CW)

  11. Effects of transition metal ion coordination on the collision-induced dissociation of polyalanines.

    PubMed

    Watson, Heather M; Vincent, John B; Cassady, Carolyn J

    2011-11-01

    Transition metal-polyalanine complexes were analyzed in a high-capacity quadrupole ion trap after electrospray ionization. Polyalanines have no polar amino acid side chains to coordinate metal ions, thus allowing the effects metal ion interaction with the peptide backbone to be explored. Positive mode mass spectra produced from peptides mixed with salts of the first row transition metals Cr(III), Fe(II), Fe(III), Co(II), Ni(II), Cu(I), and Cu(II) yield singly and doubly charged metallated ions. These precursor ions undergo collision-induced dissociation (CID) to give almost exclusively metallated N-terminal product ions whose types and relative abundances depend on the identity of the transition metal. For example, Cr(III)-cationized peptides yield CID spectra that are complex and have several neutral losses, whereas Fe(III)-cationized peptides dissociate to give intense non-metallated products. The addition of Cu(II) shows the most promise for sequencing. Spectra obtained from the CID of singly and doubly charged Cu-heptaalanine ions, [M + Cu - H](+) and [M + Cu](2+) , are complimentary and together provide cleavage at every residue and no neutral losses. (This contrasts with [M + H](+) of heptaalanine, where CID does not provide backbone ions to sequence the first three residues.) Transition metal cationization produces abundant metallated a-ions by CID, unlike protonated peptides that produce primarily b- and y-ions. The prominence of metallated a-ions is interesting because they do not always form from b-ions. Tandem mass spectrometry on metallated (Met = metal) a- and b-ions indicate that [b(n)  + Met - H](2+) lose CO to form [a(n)  + Met - H](2+), mimicking protonated structures. In contrast, [a(n)  + Met - H](2+) eliminate an amino acid residue to form [a(n-1)  + Met - H](2+), which may be useful in sequencing. PMID:22124980

  12. Metallic atoms and ions in comets: Comet Halley 1986 3

    NASA Technical Reports Server (NTRS)

    Ibadov, S.

    1992-01-01

    The origin of metallic atoms and ions in the cometary comae is investigated theoretically. Two effects are revealed in the comas of bright comets: (1) the Na anomalous type effect is possible within the gas-dust jets of comet P/Halley 1986 3 due to cooling cometary dust by cryogenic gas flow from the nucleus; and (2) the production of ions of refractory elements (Fe(+), Si(+), etc.) at large heliocentric distances is possible in the comas of the Halley type dusty comets due to high-velocity impacts between cometary and zodiacal dust particles. Spectral observations of comets with high sensitivity and spatial resolution are important for studying both comets and interplanetary dust.

  13. Metal-organic frameworks for lithium ion batteries and supercapacitors

    NASA Astrophysics Data System (ADS)

    Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang

    2015-03-01

    Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100-1000 m2 g-1) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m2 g-1), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefit from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs.

  14. Coupled polaronic and ion transport in nanocrystalline metal oxide electrodes

    NASA Astrophysics Data System (ADS)

    Rosso, Kevin

    2012-02-01

    We report new computational methods and fundamental understanding in the dynamics of coupled charge and ion transport in nanoscale metal oxides. The methods attack the multi-scale problem of simulating the collective diffusivities of ions and charge compensating e-/h+ carriers in single crystal particles, across particle-particle grain boundaries, and through networks of grains for select systems. Methods include embedded quantum mechanical clusters at the DFT and MP2 levels of theory for atomic-scale polaronic and ion transport kinetics, classical DFT-based free energy calculations for grain-scale conductivity in the framework of the Poisson-Nernst-Planck formalism, and phase field simulation of charged particle diffusivity for conductivity at the grain network scale. This combination of approaches is one of a kind in terms of its multi-scale range, scaling, and computational efficiency. We are presently focused on coupled electron and Li+ ion transport in polymorphs of TiO2, and also in mixed valence spinel oxides, for electrode conductivity optimization and improving energy storage materials performance for Li+ batteries.

  15. In-Situ Cleaning of Metal Cathodes using a Hydrogen Ion Beam

    SciTech Connect

    Dowell, D.H.; King, F.K.; Kirby, R.E.; Schmerge, J.F.; /SLAC

    2006-03-29

    Metal photocathodes are commonly used in high-field RF guns because they are robust, straightforward to implement and tolerate relatively poor vacuum compared to semi-conductor cathodes. However these cathodes have low quantum efficiency (QE) even at UV wavelengths, and still require some form of cleaning after installation in the gun. A commonly used process for improving the QE is laser cleaning. In this technique the UV drive laser is focused to a small diameter close to the metal's damage threshold and then moved across the surface to remove contaminants. This method does improve the QE, but can produce non-uniform emission and potentially damage the cathode. Ideally an alternative process which produces an atomically clean, but unaltered surface is needed. In this paper we explore using a hydrogen ion (H-ion) beam to clean a copper cathode. We describe QE measurements over the wavelength range of interest as a function of integrated exposure to an H-ion beam. We also describe the data analysis to obtain the work function and derive a formula of the QE for metal cathodes. Our measured work function for the cleaned sample is in good agreement with published values, and the theoretical QE as a function of photon wavelength is in excellent agreement with the cleaned copper experimental results. Finally, we propose an in-situ installation of an H-ion gun compatible with existing s-band RF guns.

  16. Low jitter metal vapor vacuum arc ion source for electron beam ion trap injections

    SciTech Connect

    Holland, Glenn E.; Boyer, Craig N.; Seely, John F.; Tan, J.N.; Pomeroy, J.M.; Gillaspy, J.D.

    2005-07-15

    We describe a metal vapor vacuum arc (MeVVA) ion source containing eight different cathodes that are individually selectable via the control electronics which does not require moving components in vacuum. Inside the vacuum assembly, the arc plasma is produced by means of a 30 {mu}s pulse (26 kV,125 A) delivering 2.4 mC of charge to the cathode sample material. The trigger jitter is minimized (<200 ns) to improve the capture efficiency of the ions which are injected into an ion trap. During a single discharge, the over-damped pulse produces an ion flux of 8.4x10{sup 9} ions/cm{sup 2}, measured by an unbiased Faraday cup positioned 20 cm from the extractor grid, at discharge rates up to 5 Hz. The electronic triggering of the discharge is via a fiber optic interface. We present the design, fabrication details, and performance of this MeVVA, recently installed on the National Institute of Standards and Technology electron beam ion trap (EBIT)

  17. Lithium ion battery application of porous composite oxide microcubes prepared via metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Yang, Xia; Tang, Yong-Bing; Huang, Xing; Xue, Hong Tao; Kang, Wen Pei; Li, Wen Yue; Ng, Tsz-Wai; Lee, Chun-Sing

    2015-06-01

    Prussian Blue (PB, Fe4[Fe(CN)6]3) is utilized to synthesize bimetallic metal-organic frameworks (MOFs) (Fe4[Fe(CN)6]3/Mx[Fe(CN)6], M = Cu, Ni, Co, etc.) by cation exchange, driven by differences in solubility product constant (Ksp) of monometallic MOFs. Upon decomposition, the bimetallic MOFs convert to porous composite metal oxides (Fe2O3/MOx, M = Cu, Ni, Co, etc.) while keeping the original cubic morphology. This study demonstrates a general approach for preparing bimetallic MOFs and porous composite oxides. We also demonstrate the good electrochemical performance (specific capacity of 774 mAh g-1 after 120 cycles at 500 mA g-1) of the synthesized porous Fe2O3-CuO composite as an anode material for lithium ion batteries. And according to references, this composite exhibit better or comparable rate capability and cycle stability compared with other hybrid transition metal oxides.

  18. Application of G criterion in metal vapor ion laser

    NASA Astrophysics Data System (ADS)

    Gang, Chen; Bailiang, Pan; Yi, Jin; Kun, Chen; Zhixin, Yao

    2003-09-01

    Application of G criterion to efficient operation of pulsed discharge-excited R-M transition metal vapor laser was successfully extended to univalent ionic lasing medium from neutral atomic lasing medium on the basis of analyzing the simulation results of 1.09 μm Sr + lasing process. All of the known 17 R-M transition laser lines of univalent ions follow the G criterion except one, to which an interpretation is given. Furthermore, we suggest that only 69 lines among 212 possible R-M transition laser lines predicted by S.V. Markova, which satisfy the G criterion, should be explored first.

  19. Negative ion photoelectron spectroscopy of bare transition metal dimers

    NASA Astrophysics Data System (ADS)

    Barker, Beau J.

    This thesis contains gas phase negative ion photoelectron spectra of Mo2, MoV, CrCu, MoCu and Cu2. Spectra were taken with 488 nm and 514 nm light at a resolution of 4-5 meV. Information such as electron affinities, vibrational frequencies, anharmonicities and bond dissociation energies are reported for the ground and excited electronic states of both the anion and neutral species. Theoretical calculations at the density functional level are also reported for these species. Experiment and theory are used to analyze the bonding in these bare transition metal dimers.

  20. Electrolyte materials containing highly dissociated metal ion salts

    DOEpatents

    Lee, H.S.; Geng, L.; Skotheim, T.A.

    1996-07-23

    The present invention relates to metal ion salts which can be used in electrolytes for producing electrochemical devices, including both primary and secondary batteries, photoelectrochemical cells and electrochromic displays. The salts have a low energy of dissociation and may be dissolved in a suitable polymer to produce a polymer solid electrolyte or in a polar aprotic liquid solvent to produce a liquid electrolyte. The anion of the salts may be covalently attached to polymer backbones to produce polymer solid electrolytes with exclusive cation conductivity. 2 figs.

  1. Electrolyte materials containing highly dissociated metal ion salts

    DOEpatents

    Lee, Hung-Sui; Geng, Lin; Skotheim, Terje A.

    1996-07-23

    The present invention relates to metal ion salts which can be used in electrolytes for producing electrochemical devices, including both primary and secondary batteries, photoelectrochemical cells and electrochromic displays. The salts have a low energy of dissociation and may be dissolved in a suitable polymer to produce a polymer solid electrolyte or in a polar aprotic liquid solvent to produce a liquid electrolyte. The anion of the salts may be covalently attached to polymer backbones to produce polymer solid electrolytes with exclusive cation conductivity.

  2. Theoretical study of transition-metal ions bound to benzene

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1992-01-01

    Theoretical binding energies are reported for all first-row and selected second-row transition metal ions (M+) bound to benzene. The calculations employ basis sets of at least double-zeta plus polarization quality and account for electron correlation using the modified coupled-pair functional method. While the bending is predominantly electrostatic, the binding energies are significantly increased by electron correlation, because the donation from the metal d orbitals to the benzene pi* orbitals is not well described at the self-consistent-field level. The uncertainties in the computed binding energies are estimated to be about 5 kcal/mol. Although the calculated and experimental binding energies generally agree to within their combined uncertainties, it is likely that the true binding energies lie in the lower portion of the experimental range. This is supported by the very good agreement between the theoretical and recent experimental binding energies for AgC6H6(+).

  3. Supercharging with Trivalent Metal Ions in Native Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Flick, Tawnya G.; Williams, Evan R.

    2012-11-01

    Addition of 1.0 mM LaCl3 to aqueous ammonium acetate solutions containing proteins in their folded native forms can result in a significant increase in the molecular ion charging obtained with electrospray ionization as a result of cation adduction. In combination with m-nitrobenzyl alcohol, molecular ion charge states that are greater than the number of basic sites in the protein can be produced from these native solutions, even for lysozyme, which is conformationally constrained by four intramolecular disulfide bonds. Circular dichroism spectroscopy indicates that the conformation of ubiquitin is not measurably affected with up to 1.0 M LaCl3, but ion mobility data indicate that the high charge states that are formed when 1.0 mM LaCl3 is present are more unfolded than the low charge states formed without this reagent. These and other results indicate that the increased charging is a result of La3+ preferentially adducting onto compact or more native-like conformers during ESI and the gas-phase ions subsequently unfolding as a result of increased Coulomb repulsion. Electron capture dissociation of these high charge-state ions formed from these native solutions results in comparable sequence coverage to that obtained for ions formed from denaturing solutions without supercharging reagents, making this method a potentially powerful tool for obtaining structural information in native mass spectrometry.

  4. Metal Ion Dependence of the Matrix Metalloproteinase-1 Mechanism.

    PubMed

    Yang, Hao; Makaroff, Katherine; Paz, Nicholas; Aitha, Mahesh; Crowder, Michael W; Tierney, David L

    2015-06-16

    Matrix metalloproteinase-1 (MMP-1) plays crucial roles in disease-related physiologies and pathological processes in the human body. We report here solution studies of MMP-1, including characterization of a series of mutants designed to bind metal in either the catalytic site or the structural site (but not both). Circular dichroism and fluorescence spectroscopy of the mutants demonstrate the importance of the structural Zn(II) in maintaining both secondary and tertiary structure, while UV-visible, nuclear magnetic resonance, electron paramagnetic resonance, and extended X-ray absorption fine structure show its presence influences the catalytic metal ion's coordination number. The mutants allow us to demonstrate convincingly the preparation of a mixed-metal analogue, Co(C)Zn(S)-MMP-1, with Zn(II) in the structural site and Co(II) in the catalytic site. Stopped-flow fluorescence of the native form, Zn(C)Zn(S)-MMP-1, and the mixed-metal Co(C)Zn(S)-MMP-1 analogue shows that the internal fluorescence of a nearby Trp residue is modulated with catalysis and can be used to monitor reactivity under a number of conditions, opening the door to substrate profiling. PMID:26018933

  5. Comparative toxicity of metals to freshwater life in tropical Australia

    SciTech Connect

    Markich, S.J.; Camilleri, C.; Baird, D.J.

    1995-12-31

    At present, there is a paucity of internally consistent datasets on the toxicity of metals (and other contaminants) in the tropics, relative to the cool and warm temperate regions of the world. Such information is considered mandatory before a proper comparison of the toxicity of metals to aquatic life between tropical and temperate regions is possible. As part of a larger study to investigate whether the toxicity of metals to aquatic life differs between the tropical and temperate regions of Australia, several species of tropical freshwater organisms, comprising a molluscs, fish, hydra, Daphnia and an alga were employed to obtain an internally consistent data set on the comparative toxicity of selected metals, such as U and Cu, that are of potential concern in the wet-dry tropics of Australia as a result of man`s activities. Both acute and chronic ecologically relevant sublethal endpoints, such as growth and reproduction (EC{sub 50}, BEC{sub 10}) were measured for the five species, which cover a variety of trophic levels. A synthetic water quality that closely resembled the inorganic composition of the natural waters in which the organisms inhabit, was used in all experiments. This facilitated the use of the geochemical modelling code, HARPHRQ, to predict the speciation, and hence, bioavailability of the selected metals. A knowledge of the bioavailable fraction of a metal is necessary for setting up national water quality guidelines for the protection of aquatic life. The results from this study are discussed and related to the derivation of both site-specific and national water quality-guidelines for metals.

  6. A new type of metal chelate affinity chromatography using trivalent lanthanide ions for phosphopeptide enrichment.

    PubMed

    Mirza, Munazza R; Rainer, Matthias; Messner, Christoph B; Güzel, Yüksel; Schemeth, Dieter; Stasyk, Taras; Choudhary, Muhammad I; Huber, Lukas A; Rode, Bernd M; Bonn, Günther K

    2013-05-21

    In this study, a new type of immobilized metal-ion affinity chromatography (IMAC) resin for the isolation of phosphopeptides was synthesized which is based on the specific interaction between phosphate groups and chelated lanthanide metal ions. In this regard trivalent lanthanum, holmium and erbium ions were chelated to a highly porous phosphonate polymer which was prepared by radical polymerization of vinylphosphonic acid (VPA) and divinylbenzene (DVB). The developed method was evaluated with peptide mixtures from digested standard proteins (α-casein, β-casein and ovalbumin) as well as with bovine milk, egg white and a spiked HeLa cell lysate. Compared to the commonly used TiO2 approach, the presented method showed higher selectivity for phosphorylated peptides. This can be explained by the strong preference of trivalent lanthanide ions for phosphates with which they form very tight ionic bonds. Mono- and multiply phosphorylated peptides could be enriched and released in a single basic elution step, while non-phosphorylated peptides remained on the resin. Ab initio quantum mechanical energy minimizations of model complexes for polymer-ion-ligand interactions provided geometries, binding energies and charges which are discussed in conjunction with the observed experimental properties, leading to the most satisfying agreement. The presented lanthanide-IMAC resins represent promising affinity materials for the selective isolation of phosphopeptides from biological samples. PMID:23552617

  7. The two faces of metal ions: From implants rejection to tissue repair/regeneration.

    PubMed

    Vasconcelos, Daniel M; Santos, Susana G; Lamghari, Meriem; Barbosa, Mário A

    2016-04-01

    The paradigm of metallic ions as exclusive toxic agents is changing. During the last 60 years, knowledge about toxicological and immunological reactions to metal particles and ions has advanced considerably. Hip prostheses, namely metal-on-metal bearings, have prompted studies about excessive and prolonged exposure to prosthetic debris. In that context, the interactions of metal particles and ions with cells and tissues are mostly harmful, inducing immune responses that lead to osteolysis and implant failure. However, in the last decade, new strategies to promote immunomodulation and healing have emerged based on the unique properties of metallic ions. The atom-size and charge enable ions to interact with key macromolecules (e.g. proteins, nucleic acids) that affect cellular function. Moreover, these agents are inexpensive, stable and can be integrated in biomaterials, which may open new avenues for a novel generation of medical devices. Herein, orthopedic devices are discussed as models for adverse responses to metal ions, and debated together with the potential to use metal ions-based therapies, thus bridging the gap between unmet clinical needs and cutting-edge research. In summary, this review addresses the two "faces" of metallic ions, from pathological responses to innovative research strategies that use metal ions for regenerative medicine. PMID:26851391

  8. Removal and selective recovery of heavy-metal ions from industrial waste waters. Technical completion report

    SciTech Connect

    Darnall, D.W.; Gardea-Torresdey, J.

    1989-02-01

    Accumulation of toxic metal ions in water supplies is a matter of increasingly grave concern. Primarily the undesirable by-products of mining and industrial activity, these ions can cause acute and chronic illnesses in humans and other animals. In an effort to limit further contamination, development of efficient, widely applicable, low-cost methods for removal of heavy-metal ions from waters deserves high priority. One new method that has allowed both the removal and recovery of metal ions from water has been the utilization of microorganisms such as algae. This metal-ion sorption process is based upon the natural, very strong affinity of the cell walls of algae for heavy metal ions. There appear to be distinct advantages of the immobilized algal system over other technology currently used for heavy-metal-ion cleanup from waste waters. The goals of the project were (1) to examine the effects of calcium(II) and magnesium(II) on transition metal binding to the algae, (2) to test the immobilized silica-algal polymers for removal of metal ions from electroplating plant waste waters, (3) to evaluate the effects of culturing conditions on the metal binding capacity of the resulting biomass, and (4) to investigate the mechanism of metal-ion binding to different algae.

  9. Polydopamine-mediated surface-functionalization of graphene oxide for heavy metal ions removal

    NASA Astrophysics Data System (ADS)

    Dong, Zhihui; Zhang, Feng; Wang, Dong; Liu, Xia; Jin, Jian

    2015-04-01

    By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly via a Michael-Addition reaction and produced a PEI-PD/GO composite nanosheets. The PEI-PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu2+, Cd2+, Pb2+, Hg2+ are up to 87, 106, 197, and 110 mg/g, respectively. To further make the GO based composite operable, PEI-PD/RGO aerogel was prepared through hydrothermal and achieved a high surface area up to 373 m2/g. Although the adsorption capacity of PEI-PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI-PD/GO composite dispersion (38, 32, 95, 113 mg/g corresponding to Cu2+, Cd2+, Pb2+, and Hg2+, respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater.

  10. Transition Metal Ion Complexes of Schiff-bases. Synthesis, Characterization and Antibacterial Properties

    PubMed Central

    Munawar, Asifa; Supuran, Claudiu T.

    2001-01-01

    Some novel transition metal [Co(II), Cu(II), Ni(II) and Zn(II)] complexes of substituted pyridine Schiff-bases have been prepared and characterized by physical, spectral and analytical data. The synthesized Schiff-bases act as deprotonated tridentate for the complexation reaction with Co(II), Ni(II) and Zn(II) ions. The new compounds, possessing the general formula [M(L)2] where [M=Co(II), Cu(II), Ni(II) and Zn(II) and HL=HL1, HL2, HL3 and HL4] show an octahedral geometry. In order to evaluate the effect of metal ions upon chelation, the Schiff bases and their complexes have been screened for antibacterial activity against the strains such as Escherichia coli,Staphylococcus aureus, and Pseudomonas aeruginosa. The complexed Schiff bases have shown to be more antibacterial against one more bacterial species as compared to uncomplexed Schiff-bases. PMID:18475987

  11. The effect of platform switching on the levels of metal ion release from different implant–abutment couples

    PubMed Central

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant–abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt–chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (P<0.05). Titanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant–abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant–abutment couples. PMID:27357323

  12. The effect of platform switching on the levels of metal ion release from different implant-abutment couples.

    PubMed

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant-abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt-chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (P<0.05). Titanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant-abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant-abutment couples. PMID:27357323

  13. Amperometric detection of heavy metal ions in ion pair chromatography at an array of water/nitrobenzene micro interfaces.

    PubMed

    Wilke, S; Wang, H; Muraczewska, M; Müller, H

    1996-09-01

    A novel amperometric detector for heavy metal ions has been developed and successfully applied for ion pair chromatography. The detector is based on the electrochemical transfer of the metal ions across an array of water/nitrobenzene micro interfaces. The ion transfer is facilitated by the neutral ionophores methylenebis(diphenylphosphineoxide) and methylenebis(di- phenylphosphinesulfide). More than eight metals are separated in less than 15 min on an RP18 column using octyl sulfonate as ion pair reagent. For the heavy metals, the limits of decision are 19(Pb(2+)), 9(Zn(2+)), 9l (Co(2+)), 8(Cd(2+)) and 1.6(Mn(2+)) microg/L. The applicability of the new method for water samples is demonstrated. PMID:15048359

  14. Complexation of metal ion with poly(1-vinylimidazole) resin prepared by radiation-induced polymerization with template metal ion. [Gamma radiation

    SciTech Connect

    Kato, M.; Nishide, H.; Tsuchida, E.; Sasaki, T.

    1981-07-01

    Poly(1-vinylimidazole) (PVI) resin was prepared with Ni/sup 2 +/, CO/sup 2 +/, or Zn/sup 2 +/ as a template to study the adsorption of metal ions. The metal-1-vinylimidazole complex was copolymerized and cross-linked with 1-vinyl-2-pyrrolidone by ..gamma..-ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These PVI resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites (As) and the stability constant (K) of Ni/sup 2 +/ complex were larger for the PVI resin prepared with the Ni ion template caused by the smaller dissociation rate constant of Ni ion from the resin. The composition of the Ni/sup 2 +/ complex in the resin remained constant. This suggests that the complexation proceeded via a one-step mechanism.

  15. A portable lab-on-a-chip system for gold-nanoparticle-based colorimetric detection of metal ions in water.

    PubMed

    Zhao, Chen; Zhong, Guowei; Kim, Da-Eun; Liu, Jinxia; Liu, Xinyu

    2014-09-01

    Heavy metal ions released into various water systems have a severe impact on the environment and human beings, and excess exposure to toxic metal ions through drinking water poses high risks to human health and causes life-threatening diseases. Thus, there is high demand for the development of a rapid, low-cost, and sensitive method for detection of metal ions in water. We present a portable analytical system for colorimetric detection of lead (Pb(2+)) and aluminum (Al(3+)) ions in water based on gold nanoparticle probes and lab-on-a-chip instrumentation. The colorimetric detection of metal ions is conducted via single-step assays with low limits of detection (LODs) and high selectivity. We design a custom-made microwell plate and a handheld colorimetric reader for implementing the assays and quantifying the signal readout. The calibration experiments demonstrate that this portable system provides LODs of 30 ppb for Pb(2+) and 89 ppb for Al(3+), both comparable to bench-top analytical spectrometers. It promises an effective platform for metal ion analysis in a more economical and convenient way, which is particularly useful for water quality monitoring in field and resource-poor settings. PMID:25332734

  16. Sodiation kinetics of metal oxide conversion electrodes: A comparative study with lithiation

    SciTech Connect

    He, Kai; Lin, Feng; Zhu, Yizhou; Yu, Xiqian; Li, Jing; Lin, Ruoqian; Nordlund, Dennis; Weng, Tsu Chien; Richards, Ryan M.; Yang, Xiao -Qing; Doeff, Marca M.; Stach, Eric A.; Mo, Yifei; Xin, Huolin L.; Su, Dong

    2015-08-19

    The development of sodium ion batteries (NIBs) can provide an alternative to lithium ion batteries (LIBs) for sustainable, low-cost energy storage. However, due to the larger size and higher m/e ratio of the sodium ion compared to lithium, sodiation reactions of candidate electrodes are expected to differ in significant ways from the corresponding lithium ones. In this work, we investigated the sodiation mechanism of a typical transition metal-oxide, NiO, through a set of correlated techniques, including electrochemical and synchrotron studies, real-time electron microscopy observation, and ab initio molecular dynamics (MD) simulations. We found that a crystalline Na₂O reaction layer that was formed at the beginning of sodiation plays an important role in blocking the further transport of sodium ions. In addition, sodiation in NiO exhibits a “shrinking-core” mode that results from a layer-by-layer reaction, as identified by ab initio MD simulations. For lithiation, however, the formation of Li anti-site defects significantly distorts the local NiO lattice that facilitates Li insertion, thus enhancing the overall reaction rate. These observations delineate the mechanistic difference between sodiation and lithiation in metal-oxide conversion materials. More importantly, our findings identify the importance of understanding the role of reaction layers on the functioning of electrodes and thus provide critical insights into further optimizing NIB materials through surface engineering.

  17. Sodiation kinetics of metal oxide conversion electrodes: A comparative study with lithiation

    DOE PAGESBeta

    He, Kai; Lin, Feng; Zhu, Yizhou; Yu, Xiqian; Li, Jing; Lin, Ruoqian; Nordlund, Dennis; Weng, Tsu Chien; Richards, Ryan M.; Yang, Xiao -Qing; et al

    2015-08-19

    The development of sodium ion batteries (NIBs) can provide an alternative to lithium ion batteries (LIBs) for sustainable, low-cost energy storage. However, due to the larger size and higher m/e ratio of the sodium ion compared to lithium, sodiation reactions of candidate electrodes are expected to differ in significant ways from the corresponding lithium ones. In this work, we investigated the sodiation mechanism of a typical transition metal-oxide, NiO, through a set of correlated techniques, including electrochemical and synchrotron studies, real-time electron microscopy observation, and ab initio molecular dynamics (MD) simulations. We found that a crystalline Na₂O reaction layer thatmore » was formed at the beginning of sodiation plays an important role in blocking the further transport of sodium ions. In addition, sodiation in NiO exhibits a “shrinking-core” mode that results from a layer-by-layer reaction, as identified by ab initio MD simulations. For lithiation, however, the formation of Li anti-site defects significantly distorts the local NiO lattice that facilitates Li insertion, thus enhancing the overall reaction rate. These observations delineate the mechanistic difference between sodiation and lithiation in metal-oxide conversion materials. More importantly, our findings identify the importance of understanding the role of reaction layers on the functioning of electrodes and thus provide critical insights into further optimizing NIB materials through surface engineering.« less

  18. Selective exchange of divalent transition metal ions in cryptomelane-type manganic acid with tunnel structure

    SciTech Connect

    Tsuji, M. ); Komarneni, S. )

    1993-03-01

    The ion-exchange selectivity of divalent transition metal ions on cryptomelane-type manganic acid (CMA) with tunnel structure has been studied using the distribution coefficients ([ital K][sub [ital d

  19. Metal ion sorption by untreated and chemically treated biomass

    SciTech Connect

    Kilbane, J.J.; Xie, J.

    1992-12-31

    The metal-binding ability of biosorbents is well known; however, in comparison with commercial ion-exchange resins the capacity of biosorbents is low. The purpose of this research was to examine chemically modified biosorbents and biosorbents prepared from microorganisms isolated from extreme environments to determine if significant improvements in metal-binding capacity or biosorbents with unique capabilities could be produced. Chemical treatments examined included acid, alkali, carbon disulfide, phosphorus oxychloride, anhydrous formamide, sodium thiosulfate, sodium chloroacetic acid, and phenylsulfonate. Biosorbents were prepared from microorganisms isolated from pristine and acid mine drainage impacted sites and included heterotrophs, methanotrophs, algae, and sulfate reducers. Chemical modification with carbon disulfide, phosphorous oxychloride, and sodium thiosulfate yielded biosorbents with such as much as 74%, 133%, and 155% improvements, respectively, in metal-binding capacity, but the performance of these chemically modified biosorbents deteriorated upon repeated use. A culture isolated from an acid mine drainage impacted site, IGTM17, exhibits about 3-fold higher metal-binding capacity in comparison with other biosorbents examined in this study. IGTM17 also exhibits superior metal-binding ability at decreased pH or in the presence of interfering common cations in comparison with other biosorbents or some commercially available cation exchange resins. Some biosorbents, such as IGTM5, can bind anions. To our knowledge this is the first demonstration of the ability of biosorbents to bind anions. Moreover, preliminary data indicate that the chemical modification of biosorbents may be capable of imparting the ability to selectively bind certain anions. Further research is needed to optimize conditions for the chemical modification and stabilization of biosorbents.

  20. Most spin-1/2 transition-metal ions do have single ion anisotropy

    SciTech Connect

    Liu, Jia; Whangbo, Myung-Hwan E-mail: mike-whangbo@ncsu.edu; Koo, Hyun-Joo; Xiang, Hongjun E-mail: mike-whangbo@ncsu.edu; Kremer, Reinhard K.

    2014-09-28

    The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

  1. State promotion and neutralization оf ions near metal surface

    NASA Astrophysics Data System (ADS)

    Zinoviev, A. N.

    2011-05-01

    When a multiply charged ion with charge Z approaches the metal surface, a dipole is formed by the multiply charged ion and the charge induced in the metal. The states for such a dipole are promoted into continuum with decreasing ion-surface distance and cross the states formed from metal atom. The model proposed explains the dominant population of deep bound states in collisions considered.

  2. Triboelectrification-Enabled Self-Powered Detection and Removal of Heavy Metal Ions in Wastewater.

    PubMed

    Li, Zhaoling; Chen, Jun; Guo, Hengyu; Fan, Xing; Wen, Zhen; Yeh, Min-Hsin; Yu, Chongwen; Cao, Xia; Wang, Zhong Lin

    2016-04-01

    A fundamentally new working principle into the field of self-powered heavy-metal-ion detection and removal using the triboelectrification effect is introduced. The as-developed tribo-nanosensors can selectively detect common heavy metal ions. The water-driven triboelectric nanogenerator is taken as a sustainable power source for heavy-metal-ion removal by recycling the kinetic energy from flowing wastewater. PMID:26913810

  3. Polaronic Transport in Phosphate Glasses Containing Transition Metal Ions

    NASA Astrophysics Data System (ADS)

    Henderson, Mark

    The goal of this dissertation is to characterize the basic transport properties of phosphate glasses containing various amounts of TIs and to identify and explain any electronic phase transitions which may occur. The P2 O5-V2O5-WO3 (PVW) glass system will be analyzed to find the effect of TI concentration on conduction. In addition, the effect of the relative concentrations of network forming ions (SiO2 and P2O5) on transport will be studied in the P2O5-SiO2-Fe2O 3 (PSF) system. Also presented is a numerical study on a tight-binding model adapted for the purposes of modelling Gaussian traps, mimicking TI's, which are arranged in an extended network. The results of this project will contribute to the development of fundamental theories on the electronic transport in glasses containing mixtures of transition oxides as well as those containing multiple network formers without discernible phase separation. The present study on the PVW follows up on previous investigation into the effect on mixed transition ions in oxide glasses. Past research has focused on glasses containing transition metal ions from the 3d row. The inclusion of tungsten, a 5d transition metal, adds a layer of complexity through the mismatch of the energies of the orbitals contributing to localized states. The data have indicated that a transition reminiscent of a metal-insulator transition (MIT) occurs in this system as the concentration of tungsten increases. As opposed to some other MIT-like transitions found in phosphate glass systems, there seems to be no polaron to bipolaron conversion. Instead, the individual localization parameter for tungsten noticeably decreases dramatically at the transition point as well as the adiabaticity. Another distinctive feature of this project is the study of the PSF system, which contains two true network formers, phosphorous pentoxide (P2O 5) and silicon dioxide (SiO2). It is not usually possible to do a reliable investigation of the conduction properties of

  4. A Comparative Study of Heat Transfer in Metallic Materials

    NASA Astrophysics Data System (ADS)

    Pǎucǎ, Adina; Hepuţ, Teodor; Pinca-Bretotean, Camelia; Stoica, Diana

    2011-09-01

    Rolling of metallic materials with heat transfer occurs as a result of interaction between the workpiece and the rolling cylinders incandescent. Heat transferred by diffusion into the cylinders generates variable temperature fields. These fields produce variable temperature thermal stress in each rotation cycle of rolling cylinders. This paper aims at mathematical modeling of variable temperature fields, using Matlab. These diagrams obtained are compared with those obtained following experimental study of the thermal lamination cylinders for 5 states isochronous temperature.

  5. Structure of the alkali-metal-atom + strontium molecular ions: Towards photoassociation and formation of cold molecular ions

    SciTech Connect

    Aymar, M.; Dulieu, O.; Guerout, R.

    2011-08-14

    The potential energy curves, permanent and transition dipole moments, and the static dipolar polarizability, of molecular ions composed of one alkali-metal atom and a strontium ion are determined with a quantum chemistry approach. The molecular ions are treated as effective two-electron systems and are treated using effective core potentials including core polarization, large gaussian basis sets, and full configuration interaction. In the perspective of upcoming experiments aiming at merging cold atom and cold ion traps, possible paths for radiative charge exchange, photoassociation of a cold lithium or rubidium atom and a strontium ion are discussed, as well as the formation of stable molecular ions.

  6. Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh

    2012-11-01

    New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL1 and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL2 derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML(1-2)2 have been synthesized, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate ? coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mn < Zn < Cu < Co < Ni. The ligands and their complexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu > Mn > Ni > Co > Zn.

  7. Nanoparticles reduce nickel allergy by capturing metal ions

    NASA Astrophysics Data System (ADS)

    Vemula, Praveen Kumar; Anderson, R. Rox; Karp, Jeffrey M.

    2011-05-01

    Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation.

  8. Photonic nanosensor for colorimetric detection of metal ions.

    PubMed

    Yetisen, Ali K; Montelongo, Yunuen; Qasim, Malik M; Butt, Haider; Wilkinson, Timothy D; Monteiro, Michael J; Yun, Seok Hyun

    2015-01-01

    The real-time sensing of metal ions at point of care requires integrated sensors with low energy and sample consumption, reversibility, and rapid recovery. Here, we report a photonic nanosensor that reversibly and quantitatively reports on variation in the concentrations of Pb(2+) and Cu(2+) ions in aqueous solutions (<500 μL) in the visible region of the spectrum (λ(max) ≈ 400-700 nm). A single 6 ns laser pulse (λ = 532 nm) was used to pattern an ∼10 μm thick photosensitive recording medium. This formed periodic AgBr nanocrystal (ø ∼ 5-20 nm) concentrated regions, which produced Bragg diffraction upon illumination with a white light source. The sensor functionalized with 8-hydroxyquinoline allowed sensing through inducing Donnan osmotic pressure and tuning its lattice spacing. The sensor quantitatively measured Pb(2+) and Cu(2+) ion concentrations within the dynamic range of 0.1-10.0 mM with limits of detection of 11.4 and 18.6 μM in under 10 min. The sensor could be reset in 3 min and was reused at least 100 times without compromising its accuracy. The plasmonic nanosensor represents a simple and label-free analytical platform with potential scalability for applications in medical diagnostics and environmental monitoring. PMID:25710792

  9. Nanoparticles reduce nickel allergy by capturing metal ions.

    PubMed

    Vemula, Praveen Kumar; Anderson, R Rox; Karp, Jeffrey M

    2011-05-01

    Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation. PMID:21460828

  10. Preliminary study of the metal binding site of an anti-DTPA-indium antibody by equilibrium binding immunoassays and immobilized metal ion affinity chromatography.

    PubMed

    Boden, V; Colin, C; Barbet, J; Le Doussal, J M; Vijayalakshmi, M

    1995-01-01

    Creating metal coordination sites by modifying an existing enzyme or by eliciting antibodies against metal chelate haptens is of great interest in biotechnology to create enzyme catalysts with novel specificities. Here, we investigate the metal binding potential of a monoclonal antibody raised against a DTPA-In(III) hapten (mAb 734). We study its relative binding efficiency to metals of biological relevance by equilibrium binding immunoassays and immobilized metal ion affinity chromatography, two approaches which can give complementary information regarding composition and/or structure of the metal binding site(s). Fe(III), Fe(II), Cu(II), Mg(II), Ca(II), and Zn(II) binding was compared to In(III). All of them were shown to displace indium, but their affinity for mAb 734 decreased by 100-fold compared to indium. Competitive metal binding immunoassays between Zn(II) and In(III) revealed an unusual behavior by Zn(II) which remains to be explained. Moreover, IMAC allowed us to predict the metal binding amino acids involved in the antibody paratope. The antibody metal binding site was shown to contain at least two histidine residues in a cluster, and the presence of aspartic and glutamic acid as well as cysteine residues could not be excluded. Thus, simple competition studies allows us to obtain some partial information on the metal binding structural features of this anti-metal chelate antibody and to guide our screening of its catalytic potential. PMID:7578356

  11. Spectroscopic and metal-binding properties of DF3: an artificial protein able to accommodate different metal ions

    PubMed Central

    Torres Martin de Rosales, Rafael; Faiella, Marina; Farquhar, Erik; Que, Lawrence; Andreozzi, Concetta; Pavone, Vincenzo; Maglio, Ornella; Nastri, Flavia

    2010-01-01

    The design, synthesis, and metal-binding properties of DF3, a new de novo designed di-iron protein model are described (“DF” represents due ferri, Italian for “two iron,” “di-iron”). DF3 is the latest member of the DF family of synthetic proteins. They consist of helix–loop–helix hairpins, designed to dimerize and form an antiparallel four-helix bundle that encompasses a metal-binding site similar to those of non-heme carboxylate-bridged di-iron proteins. Unlike previous DF proteins, DF3 is highly soluble in water (up to 3 mM) and forms stable complexes with several metal ions (Zn, Co, and Mn), with the desired secondary structure and the expected stoichiometry of two ions per protein. UV–vis studies of Co(II) and Fe(III) complexes confirm a metal-binding environment similar to previous di-Co(II)- and di-Fe(III)-DF proteins, including the presence of a µ-oxo-di-Fe(III) unit. Interestingly, UV–vis, EPR, and resonance Raman studies suggest the interaction of a tyro-sine adjacent to the di-Fe(III) center. The design of DF3 was aimed at increasing the accessibility of small molecules to the active site of the four-helix bundle. Indeed, binding of azide to the di-Fe(III) site demonstrates a more accessible metal site compared with previous DFs. In fact, fitting of the binding curve to the Hill equation allows us to quantify a 150% accessibility enhancement, with respect to DF2. All these results represent a significant step towards the development of a functional synthetic DF metalloprotein. PMID:20225070

  12. New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations

    SciTech Connect

    Bartsch, Richard A.

    2012-06-04

    The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

  13. Towards metals analysis using corona discharge ionization ion mobility spectrometry.

    PubMed

    Jafari, Mohammad T; Saraji, Mohammad; Sherafatmand, Hossein

    2016-02-25

    For the first time, the capability of corona discharge ionization ion mobility spectrometry (CD-IMS) in the determination of metal complex was evaluated. The extreme simplicity of dispersive liquid-liquid microextraction (DLLME) coupled to the high sensitivity of CD-IMS measurement could make this combination really useful for simple, rapid, and sensitive determination of metals in different samples. In this regard, mercury, as a model metal, was complexed with diethyldithiocarbamate (DEDTC), and then extracted into the carbon tetrachloride using DLLME. Some parameters affecting the extraction efficiency, including the type and volume of the extraction solvent, the type and volume of the disperser solvent, the concentration of the chelating agent, salt addition and, pH were exhaustively investigated. Under the optimized condition, the enrichment factor was obtained to be 142. The linear range of 0.035-10.0 μg mL(-1) with r(2) = 0.997 and the detection limit of 0.010 μg mL(-1) were obtained. The relative standard deviation values were calculated to be lower than 4% and 8% for intra-day and inter-day, respectively. Finally, the developed method was successfully applied for the extraction and determination of mercury in various real samples. The satisfactory results revealed the capability of the proposed method in trace analysis without tedious derivatization or hydride generation. PMID:26851088

  14. NEW INSTRUMENTS AND METHODS OF MEASUREMENTS: Liquid-metal ion emitters

    NASA Astrophysics Data System (ADS)

    Gabovich, M. D.

    1983-05-01

    This article describes and discusses the fundamental laws of ion emission from liquid-metal tips in a strong electric field. The widespread views of a liquid-metal emitter as being the smoothed tip of a Taylor cone are examined critically. The instability of a liquid metal in an electric field is discussed, and in line with this, an alternative concept is given of a sharp-tipped electrohydrodynamic emitter. The prospects for applying liquid-metal ion emitters are noted.

  15. Metal cation/anion adsorption on calcium carbonate: Implications to metal ion concentrations in groundwater

    SciTech Connect

    Zachara, J.M.; Cowan, C.E.; Resch, C.T.

    1990-05-01

    This chapter evaluates the sorption behavior of metallic ions on specimen calcite as a basis for determining the importance of calcite relative to other subsurface sorbents, such as layer silicates and oxides, in controlling metal ion concentration in calcareous groundwaters. A review of the literature shows the sorption of both metallic cations and anions on calcite over ranges in pH and CO{sub 2} partial pressure to be consistent with a surface-exchange process where cations exchange with surface Ca and anions exchange with surface CO{sub 3}. A general surface-exchange model was developed to account for the effects of Ca and CO{sub 3} concentrations, pH, and calcite surface area on cation and anion sorption onto calcite. The model was applied to recently developed experimental sorption data of Zn and SeO{sub 3} on specimen calcite in equilibrium CaCO{sub 3}(aq) suspensions. The surface-exchange model was able to describe the effects of pH on both cation and anion sorption, and provided good predictions of the effects of variable CO{sub 2}(g) pressure on Zn sorption and of PO{sub 4} on SeO{sub 3} sorption. The surface-exchange model, combined with sorption constants for other phases, was used to calculate Cd sorption to a hypothetical aquifer material containing a mixture of sorbents. The sorbent concentrations were fixed to those expected in groundwater zones. The multi-sorbent calculation documented the importance of calcite as a sorbent for metallic ions in groundwater.93 refs., 18 figs., 5 tabs.

  16. Fluorescent metal ion chemosensors via cation exchange reactions of complexes, quantum dots, and metal-organic frameworks.

    PubMed

    Cheng, Jinghui; Zhou, Xiangge; Xiang, Haifeng

    2015-11-01

    Due to their wide range of applications and biological significance, fluorescent sensors have been an active research area in the past few years. In the present review, recent research developments on fluorescent chemosensors that detect metal ions via cation exchange reactions (transmetalation, metal displacement, or metal exchange reactions) of complexes, quantum dots, and metal-organic frameworks are described. These complex-based chemosensors might have a much better selectivity than the corresponding free ligands/receptors because of the shielding function of the filled-in metal ions. Moreover, not only the chemical structure of the ligands/receptors but also the identity of the central metal ions have a tremendous impact on the sensing performances. Therefore, sensing via cation exchange reactions potentially provides a new, simple, and powerful way to design fluorescent chemosensors. PMID:26375420

  17. Comparative study of the synthesis of layered transition metal molybdates

    SciTech Connect

    Mitchell, S.; Gomez-Aviles, A.; Gardner, C.; Jones, W.

    2010-01-15

    Mixed metal oxides (MMOs) prepared by the mild thermal decomposition of layered double hydroxides (LDHs) differ in their reactivity on exposure to aqueous molybdate containing solutions. In this study, we investigate the reactivity of some T-Al containing MMOs (T=Co, Ni, Cu or Zn) towards the formation of layered transition metal molybdates (LTMs) possessing the general formula AT{sub 2}(OH)(MoO{sub 4}){sub 2}.H{sub 2}O, where A=NH{sub 4}{sup +}, Na{sup +} or K{sup +}. The phase selectivity of the reaction was studied with respect to the source of molybdate, the ratio of T to Mo and the reaction pH. LTMs were obtained on reaction of Cu-Al and Zn-Al containing MMOs with aqueous solutions of ammonium heptamolybdate. Rehydration of these oxides in the presence of sodium or potassium molybdate yielded a rehydrated LDH phase as the only crystalline product. The LTM products obtained by the rehydration of MMO precursors were compared with LTMs prepared by direct precipitation from the metal salts in order to study the influence of preparative route on their chemical and physical properties. Differences were noted in the composition, morphology and thermal properties of the resulting products. - Graphical abstract: Mixed metal oxides (MMOs) derived from layered double hydroxide precursors differ in their reactivity on exposure to aqueous molybdate containing solutions. We investigate the influence of the molybdate source, the rehydration pH and the ratio of T/Mo on the reactivity of some T-Al containing MMOs (T=Co, Ni, Cu or Zn) towards the formation of layered transition metal molybdates of general formula AT{sub 2}(OH)(MoO{sub 4}){sub 2}.H{sub 2}O (where A{sup +}=NH{sub 4}{sup +}, K{sup +} or Na{sup +}).

  18. Measurement of Two-Photon Absorption Cross Section of Metal Ions by a Mass Sedimentation Approach.

    PubMed

    Ma, Zhuo-Chen; Chen, Qi-Dai; Han, Bing; Liu, Xue-Qing; Song, Jun-Feng; Sun, Hong-Bo

    2015-01-01

    The photo-reduction of metal ions in solution induced by femtosecond laser is an important and novel method for fabricating three-dimensional metal microstructures. However, the nonlinear absorption cross section of metal ions remains unknown because its measurement is difficult. In the present study, a method based on Two-Photon Excited Sedimentation (TPES) is proposed to measure the two-photon absorption cross section (TPACS) of metal ions in solution. The power-squared dependence of the amount of sediment on the excitation intensity was confirmed, revealing that 800 nm femtosecond laser induced reduction of metal ions was a two photon absorption process. We believe that the proposed method may be applied to measure the TPACS of several metal ions, thereby opening a new avenue towards future analysis of two-photon absorption materials. PMID:26657990

  19. Transition metal ions at the crossroads of mucosal immunity and microbial pathogenesis

    PubMed Central

    Diaz-Ochoa, Vladimir E.; Jellbauer, Stefan; Klaus, Suzi; Raffatellu, Manuela

    2013-01-01

    Transition metal ions are essential micronutrients for all living organisms. In mammals, these ions are often protein-bound and sequestered within cells, limiting their availability to microbes. Moreover, in response to infection, mammalian hosts further reduce the availability of metal nutrients by activating epithelial cells and recruiting neutrophils, both of which release metal-binding proteins with antimicrobial function. Microorganisms, in turn, have evolved sophisticated systems to overcome these limitations and acquire the metal ions essential for their growth. Here we review some of the mechanisms employed by the host and by pathogenic microorganisms to compete for transition metal ions, with a discussion of how evading “nutritional immunity” benefits pathogens. Furthermore, we provide new insights on the mechanisms of host-microbe competition for metal ions in the mucosa, particularly in the inflamed gut. PMID:24478990

  20. Rational design of metal ion sequestering agents. 1998 annual progress report

    SciTech Connect

    Raymond, K.N.

    1998-06-01

    'This project addresses fundamental issues and requirements in developing hazardous metal ion separation technologies needed in the treatment and disposal of radioactive and chemical toxic waste. It encompasses the synthesis of new agents, followed by their characterization and evaluation, with the aim to optimize their metal ion sequestering properties for use in applied technologies. This research is focused on the following key areas: (1) basic design and synthesis of new metal ion specific sequestering ligands; (2) structural and thermodynamic investigations of these ligands and their complexes formed with the targeted metal ions; and (3) development of sequestering agents and their incorporation into systems designed to be prototypes of inexpensive and highly effective materials for hazardous metal ion decontamination. Basic studies of the sequestration of relevant toxic metals are required in order to develop processes that will treat effluents sufficiently well to allow direct release into the environment and minimize the production of secondary wastes.'

  1. Measurement of Two-Photon Absorption Cross Section of Metal Ions by a Mass Sedimentation Approach

    PubMed Central

    Ma, Zhuo-Chen; Chen, Qi-Dai; Han, Bing; Liu, Xue-Qing; Song, Jun-Feng; Sun, Hong-Bo

    2015-01-01

    The photo-reduction of metal ions in solution induced by femtosecond laser is an important and novel method for fabricating three-dimensional metal microstructures. However, the nonlinear absorption cross section of metal ions remains unknown because its measurement is difficult. In the present study, a method based on Two-Photon Excited Sedimentation (TPES) is proposed to measure the two-photon absorption cross section (TPACS) of metal ions in solution. The power-squared dependence of the amount of sediment on the excitation intensity was confirmed, revealing that 800 nm femtosecond laser induced reduction of metal ions was a two photon absorption process. We believe that the proposed method may be applied to measure the TPACS of several metal ions, thereby opening a new avenue towards future analysis of two-photon absorption materials. PMID:26657990

  2. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries.

    PubMed

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao; Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-04-01

    Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe-Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC2O4 ⋅ 2H2O and Li2CO3 using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor. PMID:25619126

  3. Process for the displacement of cyanide ions from metal-cyanide complexes

    DOEpatents

    Smith, Barbara F.; Robinson, Thomas W.

    1997-01-01

    The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous. The metal ions are released from the polymer, using dilute acid, metal ion oxidation state adjustment, or competing chelating agents, and collected and recovered or disposed of by appropriate waste management techniques. The water-soluble polymer can then be recycled. Preferred water-soluble polymers include polyethyleneimine and polyethyleneimine having a catechol or hydroxamate group.

  4. MeRNA: a Database of Metal Ion Binding Sites in RNAStructures

    SciTech Connect

    Stefan, Liliana R.; Zhang, Rui; Levitan, Aaron G.; Hendrix, DonnaF.; Brenner, Steven E.; Holbrook, Stephen R.

    2005-10-05

    Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA three-dimensional structures available from the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements; in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure, and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering.

  5. High current liquid metal ion source using porous tungsten multiemitters.

    PubMed

    Tajmar, M; Vasiljevich, I; Grienauer, W

    2010-12-01

    We recently developed an indium Liquid-Metal-Ion-Source that can emit currents from sub-μA up to several mA. It is based on a porous tungsten crown structure with 28 individual emitters, which is manufactured using Micro-Powder Injection Molding (μPIM) and electrochemical etching. The emitter combines the advantages of internal capillary feeding with excellent emission properties due to micron-size tips. Significant progress was made on the homogeneity of the emission over its current-voltage characteristic as well as on investigating its long-term stability. This LMIS seems very suitable for space propulsion as well as for micro/nano manufacturing applications with greatly increased milling/drilling speeds. This paper summarizes the latest developments on our porous multiemitters with respect to manufacturing, emission properties and long-term testing. PMID:21111260

  6. Caging Metal Ions with Visible Light-Responsive Nanopolymersomes

    PubMed Central

    2015-01-01

    Polymersomes are bilayer vesicles that self-assemble from amphiphilic diblock copolymers, and provide an attractive system for the delivery of biological and nonbiological molecules due to their environmental compatibility, mechanical stability, synthetic tunability, large aqueous core, and hyperthick hydrophobic membrane. Herein, we report a nanoscale photoresponsive polymersome system featuring a meso-to-meso ethyne-bridged bis[(porphinato)zinc] (PZn2) fluorophore hydrophobic membrane solute and dextran in the aqueous core. Upon 488 nm irradiation in solution or in microinjected zebrafish embryos, the polymersomes underwent deformation, as monitored by a characteristic red-shifted PZn2 emission spectrum and confirmed by cryo-TEM. The versatility of this system was demonstrated through the encapsulation and photorelease of a fluorophore (FITC), as well as two different metal ions, Zn2+ and Ca2+. PMID:25518002

  7. Heterogeneous behavior of metalloproteins toward metal ion binding and selectivity: insights from molecular dynamics studies.

    PubMed

    Gogoi, Prerana; Chandravanshi, Monika; Mandal, Suraj Kumar; Srivastava, Ambuj; Kanaujia, Shankar Prasad

    2016-07-01

    About one-third of the existing proteins require metal ions as cofactors for their catalytic activities and structural complexities. While many of them bind only to a specific metal, others bind to multiple (different) metal ions. However, the exact mechanism of their metal preference has not been deduced to clarity. In this study, we used molecular dynamics (MD) simulations to investigate whether a cognate metal (bound to the structure) can be replaced with other similar metal ions. We have chosen seven different proteins (phospholipase A2, sucrose phosphatase, pyrazinamidase, cysteine dioxygenase (CDO), plastocyanin, monoclonal anti-CD4 antibody Q425, and synaptotagmin 1 C2B domain) bound to seven different divalent metal ions (Ca(2+), Mg(2+), Zn(2+), Fe(2+), Cu(2+), Ba(2+), and Sr(2+), respectively). In total, 49 MD simulations each of 50 ns were performed and each trajectory was analyzed independently. Results demonstrate that in some cases, cognate metal ions can be exchanged with similar metal ions. On the contrary, some proteins show binding affinity specifically to their cognate metal ions. Surprisingly, two proteins CDO and plastocyanin which are known to bind Fe(2+) and Cu(2+), respectively, do not exhibit binding affinity to any metal ion. Furthermore, the study reveals that in some cases, the active site topology remains rigid even without cognate metals, whereas, some require them for their active site stability. Thus, it will be interesting to experimentally verify the accuracy of these observations obtained computationally. Moreover, the study can help in designing novel active sites for proteins to sequester metal ions particularly of toxic nature. PMID:26248730

  8. Photoluminescence properties of Jahn-Teller transition-metal ions

    NASA Astrophysics Data System (ADS)

    Sanz-Ortiz, Marta N.; Rodríguez, Fernando

    2009-09-01

    This work investigates the influence of electron-phonon coupling associated with E ⊗e and T ⊗e Jahn-Teller (JT) effect in different transition-metal (TM) ions on de-excitation phenomena through nonradiative multiphonon relaxation, i.e., photoluminescence (PL) quenching. We developed a configurational curve model which is able to predict from the absorption spectrum whether a given JT-TM ion is PL or quenched. The prediction is made on the basis of an adapted Dexter-Klick-Russell parameter for JT systems, defined in terms of spectroscopic parameters through ΛJT=αΔeabs/Eabs, where Δeabs refers to the splitting of the parent octahedral Eg states by the JT distortion in E ⊗e (α =3/4) or T ⊗e (α =1/4), and Eabs is the energy of the first absorption band involving electronic transition between Eg and T2g. We show that PL in any JT-TM ion occurs whenever ΛJT<0.1 or is quenched if ΛJT>0.2. This result is noteworthy since it allows us to establish structural requirements for the JT-TM ion and the host crystal to be PL. Although PL properties of materials containing TM ions depend on a variety of structural factors such as the electronic configuration, the site symmetry, and the crystal field produced by neighboring atoms, the present model achieves this goal through a simple spectroscopic parameter: ΛJT. In this work we correlated the PL properties of different sixfold-coordinated JT systems such as Ti3+, Cu2+, Mn3+, Cr2+, Fe2+, Co3+, and Ni3+ in halides and oxides with ΛJT obtained from their respective absorption spectra. From this analysis we conclude that depending on the nature of the JT coupling and its strength, PL is either strongly favored or quenched in T ⊗e while it is mostly quenched in E ⊗e systems due to the larger JT distortion.

  9. Comparative effects of chelating drugs on trace metal and biochemical alterations in the rat

    SciTech Connect

    Misra, M.; Athar, M.; Hasan, S.K.; Srivastava, R.C.

    1988-08-01

    Chelation therapy is the most successful modality for the management of heavy metal poisoning. The success of these drugs stem from their multidentate polyfunctional chelating behavior. The therapeutic mechanism for chelating drugs involves their interaction with toxic metals leading to their rapid excretion from the body. However, because of their indiscriminate affinity for various metal ions, the potential interactions between these drugs and endogenous trace metals is of concern. It was, therefore, of importance to define new chelating drugs which in addition to being effective as an antidote in metal poisoning may possess low undesirable toxicity. In the present communication the authors compare the acute effect of Cyclam with those of other conventional chelating drugs namely, triethylenetetramine (TETA), reduced glutathione (GSH), ethylenediamine tetraacetic acid (EDTA), cyclohexanediamine tetraacetic acid (CDTA), diethylene triamine pentaacetic acid (DTPA) and hydroxyethylenediamine triacetic acid (HEDTA) on (i) serum levels of Cu, Zn, lactate dehydrogenase (LDH), glutamyloxaloacetic transaminase (GOT) and ceruloplasmin (CP); (ii) hepatic and renal levels of Cu, Mn, Zn and Fe and (iii) hepatic and renal levels of GSH, glutathione-S-transferase (GST) and phosphoglucomutase (PGM) at various time intervals (16, 24 and 72 hrs) after their administration to rats.

  10. Theoretical studies of the first- and second-row transition-metal methyls and their positive ions

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry; Barnes, Leslie A.

    1989-01-01

    The metal-carbon bond-dissociation energies (D0) and geometries for the first- and second-row transition-metal methyl neutrals and positive ions are determined. The computed D0 values for the positive ions compare favorably with experiment, except for RuCH3(+), RhCH3(+), and PdCH3(+), where the experimental values are 10-15 kcal/mol larger. The computed D0 values for the hydride and methyl positive ions are similar for all metals in both transition rows, except for Cu and Ag. However, for the neutral systems, the D0 values for the methyls are smaller, especially on the right-hand side of both transition rows, where the differences approach 15 kcal/mol.

  11. Comparative study of the synthesis of layered transition metal molybdates

    NASA Astrophysics Data System (ADS)

    Mitchell, S.; Gómez-Avilés, A.; Gardner, C.; Jones, W.

    2010-01-01

    Mixed metal oxides (MMOs) prepared by the mild thermal decomposition of layered double hydroxides (LDHs) differ in their reactivity on exposure to aqueous molybdate containing solutions. In this study, we investigate the reactivity of some T-Al containing MMOs ( T=Co, Ni, Cu or Zn) towards the formation of layered transition metal molybdates (LTMs) possessing the general formula AT2(OH)(MoO 4) 2·H 2O, where A=NH 4+, Na + or K +. The phase selectivity of the reaction was studied with respect to the source of molybdate, the ratio of T to Mo and the reaction pH. LTMs were obtained on reaction of Cu-Al and Zn-Al containing MMOs with aqueous solutions of ammonium heptamolybdate. Rehydration of these oxides in the presence of sodium or potassium molybdate yielded a rehydrated LDH phase as the only crystalline product. The LTM products obtained by the rehydration of MMO precursors were compared with LTMs prepared by direct precipitation from the metal salts in order to study the influence of preparative route on their chemical and physical properties. Differences were noted in the composition, morphology and thermal properties of the resulting products.

  12. Evaluation of Metal Phosphide Nanocrystals as Anode Materials for Na-ion Batteries.

    PubMed

    Walter, Marc; Bodnarchuk, Maryna I; Kravchyk, Kostiantyn V; Kovalenko, Maksym V

    2015-01-01

    Sodium-ion batteries (SIBs) are potential low-cost alternatives to lithium-ion batteries (LIBs) because of the much greater natural abundance of sodium salts. However, developing high-performance electrode materials for SIBs is a challenging task, especially due to the ∼50% larger ionic radius of the Na(+) ion compared to Li(+), leading to vastly different electrochemical behavior. Metal phosphides such as FeP, CoP, NiP(2), and CuP(2) remain unexplored as electrode materials for SIBs, despite their high theoretical charge storage capacities of 900-1300 mAh g(-1). Here we report on the synthesis of metal phosphide nanocrystals (NCs) and discuss their electrochemical properties as anode materials for SIBs, as well as for LIBs. We also compare the electrochemical characteristics of phosphides with their corresponding sulfides, using the environmentally benign iron compounds, FeP and FeS(2), as a case study. We show that despite the appealing initial charge storage capacities of up to 1200 mAh g(-1), enabled by effective nanosizing of the active electrode materials, further work toward optimization of the electrode/electrolyte pair is needed to improve the electrochemical performance upon cycling. PMID:26842319

  13. Divalent ion encapsulated nano titania on Ti metal as a bioactive surface with enhanced protein adsorption.

    PubMed

    Anbazhagan, Esaitamil; Rajendran, Archana; Natarajan, Duraipandy; Kiran, M S; Pattanayak, Deepak K

    2016-07-01

    A novel approach on incorporation of divalent species such as Mg, Ca and Sr into the titania nanostructures formed on Ti metal surface and their comparative study on enhancement of bioactivity, protein adsorption and cell compatibility is reported. When treated with hydrogen peroxide, Ti metal forms hydrogen titanate. On subsequent treatment with Mg or Ca or Sr nitrate solutions, respective ions are incorporated into hydrogen titanate layer, and heat treatment leads to titania decorated with these ions. The resultant heat-treated samples when soaked in simulated body fluid form bone-like apatite which indicates the present surface modification enhances the bioactivity. Further, enhanced protein adsorption in bovine serum albumin is an indication of suitability of these divalent species to form chelate compounds with amino acids, and Ca containing titania nanostructure favours more protein adsorption compared to the others. Cytocompatibility studies using MG-63, human osteosarcoma cell lines shows these divalent ion containing titania nanostructure favours the cell attachment and did not show any cytotoxicity. Bioactivity, enhanced protein adsorption along with cytocompatibility clearly indicates such surface modification approach to be useful to design hard tissue replacement materials in orthopaedic and dental field. PMID:27011351

  14. Metal-clad optical waveguide fluorescence device for the detection of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Margheri, Giancarlo; Giorgetti, Emilia; Marsili, Paolo; Zoppi, Angela; Lascialfari, Luisa; Cicchi, Stefano

    2014-07-01

    We developed Hg-sensing chips by decorating the external surface of metal-clad optical waveguides with a monolayer of Hg-sensitive fluorescent molecular probes. The emission properties of the original water-soluble form of the molecule were previously found to be selectively quenched in the presence of Hg ions. The fabricated samples were tested with optical waveguide fluorescence spectroscopy by putting them in contact with a 5-μM water solution of Hg ions and recording the emission spectra versus incubation time. The estimate of the limit of detection was 150 nM. A preliminary evaluation of the selectivity of the structure was also performed by using Cd as possible interfering analytes.

  15. High energy metal ion implantation using `Magis`, a novel, broad-beam, Marx-generator-based ion source

    SciTech Connect

    Anders, A.; Brown, I.G.; Dickinson, M.R.; MacGill, R.A.

    1996-08-01

    Ion energy of the beam formed by an ion source is proportional to extractor voltage and ion charge state. Increasing the voltage is difficult and costly for extraction voltage over 100 kV. Here we explore the possibility of increasing the charge states of metal ions to facilitate high-energy, broad beam ion implantation at a moderate voltage level. Strategies to enhance the ion charge state include operating in the regimes of high-current vacuum sparks and short pulses. Using a time-of-flight technique we have measured charge states as high as 7+ (73 kA vacuum spark discharge) and 4+ (14 kA short pulse arc discharge), both for copper, with the mean ion charge states about 6.0 and 2.5, respectively. Pulsed discharges can conveniently be driven by a modified Marx generator, allowing operation of ``Magis`` with a single power supply (at ground potential) for both plasma production and ion extraction.

  16. New highly sensitive and selective catalytic DNA biosensors for metal ions.

    PubMed

    Lu, Yi; Liu, Juewen; Li, Jing; Bruesehoff, Peter J; Pavot, Caroline M-B; Brown, Andrea K

    2003-05-01

    While remarkable progress has been made in developing sensors for metal ions such as Ca(II) and Zn(II), designing and synthesizing sensitive and selective metal ion sensors remains a significant challenge. Perhaps the biggest challenge is the design and synthesis of a sensor capable of specific and strong metal binding. Since our knowledge about the construction of metal-binding sites in general is limited, searching for sensors in a combinatorial way is of significant value. Therefore, we have been able to use a combinatorial method called in vitro selection to obtain catalytic DNA that can bind a metal ion of choice strongly and specifically. The metal ion selectivity of the catalytic DNA was further improved using a 'negative selection' strategy where catalytic DNA that are selective for competing metal ions are discarded in the in vitro selection processes. By labeling the resulting catalytic DNA with a fluorophore/quencher pair, we have made a new class of metal ion fluorescent sensors that are the first examples of catalytic DNA biosensors for metal ions. The sensors combine the high selectivity of catalytic DNA with the high sensitivity of fluorescent detection, and can be applied to the quantitative detection of metal ions over a wide concentration range and with high selectivity. The use of DNA sensors in detection and quantification of lead ions in environmental samples such as water from Lake Michigan has been demonstrated. DNA is stable, cost-effective, environmentally benign, and easily adaptable to optical fiber and microarray technology for device manufacture. Thus, the DNA sensors explained here hold great promise for on-site and real-time monitoring of metal ions in the fields of environmental monitoring, developmental biology, clinical toxicology, wastewater treatment, and industrial process monitoring. PMID:12706559

  17. Divalent Metal-Ion Complexes with Dipeptide Ligands Having Phe and His Side-Chain Anchors: Effects of Sequence, Metal Ion, and Anchor.

    PubMed

    Dunbar, Robert C; Berden, Giel; Martens, Jonathan K; Oomens, Jos

    2015-09-24

    Conformational preferences have been surveyed for divalent metal cation complexes with the dipeptide ligands AlaPhe, PheAla, GlyHis, and HisGly. Density functional theory results for a full set of complexes are presented, and previous experimental infrared spectra, supplemented by a number of newly recorded spectra obtained with infrared multiple photon dissociation spectroscopy, provide experimental verification of the preferred conformations in most cases. The overall structural features of these complexes are shown, and attention is given to comparisons involving peptide sequence, nature of the metal ion, and nature of the side-chain anchor. A regular progression is observed as a function of binding strength, whereby the weakly binding metal ions (Ba(2+) to Ca(2+)) transition from carboxylate zwitterion (ZW) binding to charge-solvated (CS) binding, while the stronger binding metal ions (Ca(2+) to Mg(2+) to Ni(2+)) transition from CS binding to metal-ion-backbone binding (Iminol) by direct metal-nitrogen bonds to the deprotonated amide nitrogens. Two new sequence-dependent reversals are found between ZW and CS binding modes, such that Ba(2+) and Ca(2+) prefer ZW binding in the GlyHis case but prefer CS binding in the HisGly case. The overall binding strength for a given metal ion is not strongly dependent on the sequence, but the histidine peptides are significantly more strongly bound (by 50-100 kJ mol(-1)) than the phenylalanine peptides. PMID:26325483

  18. Influence of metal ions on the interaction between gatifloxacin and calf thymus DNA

    NASA Astrophysics Data System (ADS)

    Yuan, Xiao-ying; Qin, Jun; Lu, Ling-ling

    2010-02-01

    To study the interaction between gatifloxacin (GT), metal ions (Cu 2+, Cd 2+, Co 2+, Mg 2+) and calf thymus DNA under condition of physiology pH, UV absorption and fluorescence methods were adopted. Result shows that metal ions and DNA are able to react with GT in ground state. In further research, by studying the influence of metal ions on binding of GT with DNA in metal ions-GT-DNA ternary system, we found that influential mechanism of Mg 2+ on the binding of GT with DNA may be different from the other three. Mg 2+ can act as a bridge in the binding of GT's carboxyl/carbonyl with DNA phosphate in certain concentration range; while Cu 2+, Cd 2+, Co 2+ can combine directly with GT by reaction between GT carboxyl/carbonyl and DNA base, and enhance the binding ability of GT with DNA. The influence extent and type depend not only on the binding site of DNA with metal ions (phosphate or base), but also the binding ability of which. The stronger the binding ability of metal ions with DNA base is, the larger their promotion to binding of GT with DNA is. The order of metal ions' influential ability on the binding of GT-DNA is identical to the binding ability order of metal ions with DNA base, that is: Cu 2+ > Cd 2+ > Co 2+ > Mg 2+.

  19. Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

    Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

  20. Using diastereopeptides to control metal ion coordination in proteins.

    PubMed

    Peacock, Anna F A; Hemmingsen, Lars; Pecoraro, Vincent L

    2008-10-28

    Here, we report a previously undescribed approach for controlling metal ion coordination geometry in biomolecules by reorientating amino acid side chains through substitution of L- to D-amino acids. These diastereopeptides allow us to manipulate the spatial orientation of amino acid side chains to alter the sterics of metal binding pockets. We have used this approach to design the de novo metallopeptide, Cd(TRIL12L(D)L16C)(3)(-), which is an example of Cd(II) bound to 3 L-Cys as exclusively trigonal CdS(3), as characterized by a combination of (113)Cd NMR and (111m)Cd PAC spectroscopy. We subsequently show that the physical properties of such a site, such as the high pK(a2) for Cd(II) binding of 15.1, is due to the nature of the coordination number and not the ligating group. Further more this approach allowed for the design of a construct, GRANDL12L(D)L16CL26AL30C, capable of independently binding 2 equivalents of Cd(II) to 2 very similar Cys sites as exclusively 3- and 4-, CdS(3) and CdS(3)O, respectively. Demonstrating that we are capable of controlling the Cd(II) coordination number in these 2 sites solely by varying the nature of a noncoordinating second coordination sphere amino acid, with D-leucine and L-alanine resulting in exclusively 3- and 4-coordinate structures, respectively. Cd(II) was found to selectively bind to the 4-coordinate CdS(3)O site, demonstrating that a protein can be designed that displays metal-binding selectivity based solely on coordination number control and not on the chemical identity of coordinating ligands. PMID:18940928

  1. The interaction between oxytetracycline and divalent metal ions in aqueous and mixed solvent systems.

    PubMed

    Tongaree, S; Flanagan, D R; Poust, R I

    1999-01-01

    The effects of pH, mixed solvent systems, and divalent metal ions on oxytetracycline (OTC) solubility and the interactions between OTC and metal ions in aqueous and mixed solvent systems were investigated. OTC solubility profiles were obtained for pH 4-9. The cosolvents studied were glycerin, propylene glycol, PEG 400, and 2-pyrrolidone with the following metal ions: magnesium, calcium, and zinc. OTC and its interactions with these metal ions were evaluated by solubility, NMR, circular dichroism (CD), and electron diffraction (ED) methods. At pH 5.6, no complexation occurred with these metal ions, but OTC zwitterion formed aggregates in aqueous solutions as shown by NMR spectra. The hydration of the metal ions was observed to affect OTC aggregation, with Mg+2 causing the greatest OTC aggregation. At pH 7.5, OTC aggregation and metal-OTC complexation were observed in solutions with Ca+2 and Mg+2. Zinc ion was found to decrease OTC solubility because of zincate formation, which caused anionic OTC to precipitate. Electron diffraction revealed a relationship between OTC and metal-OTC complex crystallinity and solubility behavior. The zinc-OTC complex exhibited the highest crystallinity and lowest solubility at pH 8.0. Various cosolvents generally enhanced OTC solubility, with 2-pyrrolidone having the best solubility power. In OTC-metal-2-pyrrolidone and OTC-Zn(+2)-PEG 400 systems, circular dichroism provided evidence for the formation of soluble ternary complexes. PMID:10578513

  2. Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity.

    PubMed

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh

    2012-11-01

    New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL(1) and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL(2) derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML((1-2)2) have been synthesized, where M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mnmetal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu>Mn>Ni>Co>Zn. PMID:22813991

  3. Multiheteromacrocycles that Complex Metal Ions. Sixth Progress Report, 1 May 1979-30 April 1980

    DOE R&D Accomplishments Database

    Cram, D. J.

    1980-01-15

    Objective is to design synthesize, and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes, and their clusters. Host organic compounds consist of strategically placed solvating, coordinating, and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions or by metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; number of binding sites; character of binding sites; and valences. During this period, hemispherands based on an aryloxy or cyclic urea unit, spherands based on aryloxyl units only, and their complexes with alkali metals and alkaline earths were investigated. An attempt to separate {sup 6}Li and {sup 7}Li by gel permeation chromatography of lithiospherium chloride failed. (DLC)

  4. An artificial tongue fluorescent sensor array for identification and quantitation of various heavy metal ions.

    PubMed

    Xu, Wang; Ren, Changliang; Teoh, Chai Lean; Peng, Juanjuan; Gadre, Shubhankar Haribhau; Rhee, Hyun-Woo; Lee, Chi-Lik Ken; Chang, Young-Tae

    2014-09-01

    Herein, a small-molecule fluorescent sensor array for rapid identification of seven heavy metal ions was designed and synthesized, with its sensing mechanism mimicking that of a tongue. The photoinduced electron transfer and intramolecular charge transfer mechanism result in combinatorial interactions between sensor array and heavy metal ions, which lead to diversified fluorescence wavelength shifts and emission intensity changes. Upon principle component analysis (PCA), this result renders clear identification of each heavy metal ion on a 3D spatial dispersion graph. Further exploration provides a concentration-dependent pattern, allowing both qualitative and quantitative measurements of heavy metal ions. On the basis of this information, a "safe-zone" concept was proposed, which provides rapid exclusion of versatile hazardous species from clean water samples based on toxicity characteristic leaching procedure standards. This type of small-molecule fluorescent sensor array could open a new avenue for multiple heavy metal ion detection and simplified water quality analysis. PMID:25144824

  5. Interaction of lactic acid bacteria with metal ions: opportunities for improving food safety and quality.

    PubMed

    Mrvčić, Jasna; Stanzer, Damir; Solić, Ema; Stehlik-Tomas, Vesna

    2012-09-01

    Certain species of lactic acid bacteria (LAB), as well as other microorganisms, can bind metal ions to their cells surface or transport and store them inside the cell. Due to this fact, over the past few years interactions of metal ions with LAB have been intensively investigated in order to develop the usage of these bacteria in new biotechnology processes in addition to their health and probiotic aspects. Preliminary studies in model aqueous solutions yielded LAB with high absorption potential for toxic and essential metal ions, which can be used for improving food safety and quality. This paper provides an overview of results obtained by LAB application in toxic metal ions removing from drinking water, food and human body, as well as production of functional foods and nutraceutics. The biosorption abilities of LAB towards metal ions are emphasized. The binding mechanisms, as well as the parameters influencing the passive and active uptake are analyzed. PMID:22806724

  6. Graphene-DNAzyme Junctions: A Platform for Direct Metal Ion Detection with Ultrahigh Sensitivity

    PubMed Central

    Gao, Li; Li, Le-Le; Wang, Xiaolong; Wu, Peiwen; Cao, Yang; Liang, Bo; Li, Xin; Lin, Yuanwei

    2015-01-01

    Many metal ions are present in biology and in the human body in trace amounts. Despite numerous efforts, metal sensors with ultrahigh sensitivity (< a few picomolar) are rarely achieved. Here, we describe a platform method that integrates a Cu2+-dependent DNAzyme into graphene-molecule junctions and its application for direct detection of paramagnetic Cu2+ with femtomolar sensitivity and high selectivity. Since DNAzymes specific for other metal ions can be obtained through in vitro selection, the method demonstrated here can be applied to the detection of a broad range of other metal ions. PMID:26417425

  7. Method for forming metallic silicide films on silicon substrates by ion beam deposition

    DOEpatents

    Zuhr, Raymond A.; Holland, Orin W.

    1990-01-01

    Metallic silicide films are formed on silicon substrates by contacting the substrates with a low-energy ion beam of metal ions while moderately heating the substrate. The heating of the substrate provides for the diffusion of silicon atoms through the film as it is being formed to the surface of the film for interaction with the metal ions as they contact the diffused silicon. The metallic silicide films provided by the present invention are contaminant free, of uniform stoichiometry, large grain size, and exhibit low resistivity values which are of particular usefulness for integrated circuit production.

  8. Metal ion transport quantified by ICP-MS in intact cells

    PubMed Central

    Figueroa, Julio A. Landero; Stiner, Cory A.; Radzyukevich, Tatiana L.; Heiny, Judith A.

    2016-01-01

    The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions. PMID:26838181

  9. Sunflower stalks as adsorbents for the removal of metal ions from wastewater

    SciTech Connect

    Sun, G.; Shi, W.

    1998-04-01

    Sunflower stalks as adsorbents for the removal of metal ions such as copper, cadmium, zinc, and chromium ions in aqueous solutions were studied with equilibrium isotherms and kinetic adsorptions. The maximum adsorptions of four heavy metals are 29.3 mg/g (Cu{sup 2+}), 30.73 mg/g (Zn{sup 2+}), 42.18 mg/g (Cd{sup 2+}), and 25.07 mg/g (Cr{sup 3+}), respectively. Particle sizes of sunflower stalks affected the adsorption of metal ions; the finer size of particles showed better adsorption to the ions. Temperature also plays an interesting role in the adsorption of different metal ions. Copper, zinc, and cadmium exhibited lower adsorption on sunflower stalks at higher temperature, while chromium showed the opposite phenomenon. The adsorption rates of copper, cadmium, and chromium are quite rapid. Within 60 min of operation about 60--80% of these ions were removed from the solutions.

  10. Thio Effects and an Unconventional Metal Ion Rescue in the Genomic HDV Ribozyme§

    PubMed Central

    Thaplyal, Pallavi; Ganguly, Abir; Golden, Barbara L.; Hammes-Schiffer, Sharon; Bevilacqua, Philip C.

    2013-01-01

    Metal ion and nucleobase catalysis are important for ribozyme mechanism, but the extent to which they cooperate is unclear. A crystal structure of the hepatitis delta virus (HDV) ribozyme suggested that the pro-RP oxygen at the scissile phosphate directly coordinates a catalytic Mg2+ ion and is within hydrogen bonding distance of the amine of the general acid C75. Prior studies on the genomic HDV ribozyme, however, showed neither a thio effect nor metal ion rescue using Mn2+. Here, we combine experiment and theory to explore phosphorothioate substitutions at the scissile phosphate. We report significant thio effects at the scissile phosphate and metal ion rescue with Cd2+. Reaction profiles with an SP-phosphorothioate substitution are indistinguishable from those of the unmodified substrate in the presence of Mg2+ or Cd2+, supporting that the pro-SP oxygen does not coordinate metal ions. The RP-phosphorothioate substitution, however, exhibits biphasic kinetics, with the fast-reacting phase displaying a thio effect of up to 5-fold effect and the slow-reacting phase displaying a thio effect of ~1,000-fold. Moreover, the fast- and slow-reacting phases give metal ion rescues in Cd2+ of up to 10- and 330-fold, respectively. The metal ion rescues are unconventional in that they arise from Cd2+ inhibiting the oxo substrate but not the RP substrate. This metal ion rescue suggests a direct interaction of the catalytic metal ion with the pro-RP oxygen, in line with experiments on the antigenomic HDV ribozyme. Experiments without divalent ions, with mutants that interfere with Mg2+ binding, or with C75 deleted suggest that the pro-RP oxygen plays at most a redundant role in positioning C75. Quantum mechanical/molecular mechanical (QM/MM) studies indicate that the metal ion contributes to catalysis by interacting with both the pro-RP oxygen and the nucleophilic 2’- hydroxyl, supporting the experimental findings. PMID:24001219

  11. METAL INTERACTIONS AT SULFIDE MINERAL SURFACES: PART 3, METAL AFFINITIES IN SINGLE AND MULTIPLE ION ADSORPTION REACTIONS

    EPA Science Inventory

    Adsorption reactions of both single ions and multiple ion mixtures with sulfide minerals (chalcocite, galena, pyrite, and sphalerite) were investigated in the metal concentration range of 0.0001 to 0.00001 M. Chromium (III), iron (III), barium (II), cadmium (II), copper (II), nic...

  12. Photocatalytic activity of transition-metal-ion-doped coordination polymer (CP): photoresponse region extension and quantum yields enhancement via doping of transition metal ions into the framework of CPs.

    PubMed

    Xu, Xin-Xin; Cui, Zhong-Ping; Gao, Xin; Liu, Xiao-Xia

    2014-06-21

    To improve photocatalytic activity of a coordination polymer (CP) in the visible light region, five different transition metal ions (Fe(3+), Cr(3+), Ru(3+), Co(2+) and Ni(2+)) were introduced into its framework through an ion-exchange process. Among all the resulting transition metal ion doped coordination polymers (TMI/CPs), the one doped with Fe(3+) took on the most excellent photocatalytic activity and the highest quantum yields in the visible light region, decomposing 94% Rhodamine B (RhB) in 8 hours. It can be attributed to the doping of Fe(3+), which reduced the band gap (Eg) of the original CP, facilitating photocatalysis of the obtained polymer. Compared with the coordination polymer with Fe(3+) as a dopant, products doped with other metal ions presented weaker photocatalytic activities in the visible light region, while under the irradiation of ultraviolet light, they showed favorable photocatalytic properties. The results suggest that to dope transition metal ions into the framework of CPs would be an ideal option for enhancing the photocatalytic activity of coordination polymers. PMID:24781645

  13. Identifying alkali metal inhibitors of crystal growth: a selection criterion based on ion pair hydration energy.

    PubMed

    Farmanesh, Sahar; Alamani, Bryan G; Rimer, Jeffrey D

    2015-09-21

    We show that alkali metals function as effective modifiers of calcium oxalate monohydrate (COM) crystallization wherein alkali-oxalate ion parings reduce the rate of crystal growth by as much as 60%. Our findings reveal a distinct trend in alkali metal efficacy that cannot be explained by colloidal theories or simple descriptors, such as ion size, but is consistent with a theoretical model that accounts for the ion pair's affinity for water. PMID:26242310

  14. Sputtered metal and silicon cluster ions: collision-induced fragmentation and neutralization

    NASA Astrophysics Data System (ADS)

    Begemann, W.; Hector, R.; Liu, Y. Y.; Tiggesbäumker, J.; Meiwes-Broer, K. H.; Lutz, H. O.

    1989-03-01

    Mass separated metal and silicon cluster ion beams M{/n +, -} are produced by sputtering and undergo fragmenting and/or neutralizing collisions at different kinetic energies (100 1800 eV) in Ar and SF6. Fragment patterns induced by rare gas collisions open a way to determine ionization potentials and electron affinities of clusters. These values are compared to known experimental and theoretical data. For negatively charged clusters the absorption in gas targets is mainly due to neutralization, the cross sections varying with cluster material, number of atoms and collision partner from 10 Å2 to about 50 Å2.

  15. Formation of metallic nanostructures on the surface of ion- exchange glass by focused electron beam

    NASA Astrophysics Data System (ADS)

    Komissarenko, F. E.; Zhukov, M. V.; Mukhin, I. S.; Golubok, A. O.; Sidorov, A. I.

    2015-11-01

    This paper presents a new method for formation of metallic nanostructures on the surface of ion-exchange glass. The method is based on the interaction of a focused electron beam with ions in ion-exchange glass. In experiments nanostructures with different shapes were obtained, depending on the electrons irradiation conditions.

  16. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries

    SciTech Connect

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-04-15

    Highlights: • Selective precipitation and solvent extraction were adopted. • Nickel, cobalt and lithium were selectively precipitated. • Co-D2EHPA was employed as high-efficiency extraction reagent for manganese. • High recovery percentages could be achieved for all metal values. - Abstract: Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe–Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC{sub 2}O{sub 4}⋅2H{sub 2}O and Li{sub 2}CO{sub 3} using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor.

  17. A crystallographic study of the binding of 13 metal ions to two related RNA duplexes

    PubMed Central

    Ennifar, Eric; Walter, Philippe; Dumas, Philippe

    2003-01-01

    Metal ions, and magnesium in particular, are known to be involved in RNA folding by stabilizing secondary and tertiary structures, and, as cofactors, in RNA enzymatic activity. We have conducted a systematic crystallographic analysis of cation binding to the duplex form of the HIV-1 RNA dimerization initiation site for the subtype-A and -B natural sequences. Eleven ions (K+, Pb2+, Mn2+, Ba2+, Ca2+, Cd2+, Sr2+, Zn2+, Co2+, Au3+ and Pt4+) and two hexammines [Co (NH3)6]3+ and [Ru (NH3)6]3+ were found to bind to the DIS duplex structure. Although the two sequences are very similar, strong differences were found in their cation binding properties. Divalent cations bind almost exclusively, as Mg2+, at ‘Hoogsteen’ sites of guanine residues, with a cation-dependent affinity for each site. Notably, a given cation can have very different affinities for a priori equivalent sites within the same molecule. Surprisingly, none of the two hexammines used were able to efficiently replace hexahydrated magnesium. Instead, [Co (NH3)4]3+ was seen bound by inner-sphere coordination to the RNA. This raises some questions about the practical use of [Co (NH3)6]3+ as a [Mg (H2O)6]2+ mimetic. Also very unexpected was the binding of the small Au3+ cation exactly between the Watson–Crick sites of a G-C base pair after an obligatory deprotonation of N1 of the guanine base. This extensive study of metal ion binding using X-ray crystallography significantly enriches our knowledge on the binding of middleweight or heavy metal ions to RNA, particularly compared with magnesium. PMID:12736317

  18. Binding of monovalent alkali metal ions with negatively charged phospholipid membranes.

    PubMed

    Maity, Pabitra; Saha, Baishakhi; Kumar, Gopinatha Suresh; Karmakar, Sanat

    2016-04-01

    We have systematically investigated the effect of various alkali metal ions with negatively charged phospholipid membranes. Size distributions of large unilamellar vesicles have been confirmed using dynamic light scattering. Zeta potential and effective charges per vesicle in the presence of various alkali metal ions have been estimated from the measured electrophoretic mobility. We have determined the intrinsic binding constant from the zeta potential using electrostatic double layer theory. The reasonable and consistent value of the intrinsic binding constant of Na(+), found at moderate NaCl concentration (10-100 mM), indicates that the Gouy-Chapman theory cannot be applied for very high (> 100mM) and very low (< 10 mM) electrolyte concentrations. The isothermal titration calorimetry study has revealed that the net binding heat of interaction of the negatively charged vesicles with monovalent alkali metal ions is small and comparable to those obtained from neutral phosphatidylcholine vesicles. The overall endothermic response of binding heat suggests that interaction is primarily entropy driven. The entropy gain might arise due to the release of water molecules from the hydration layer vicinity of the membranes. Therefore, the partition model which does not include the electrostatic contribution suffices to describe the interaction. The binding constant of Na(+) (2.4 ± 0.1 M(-1)), obtained from the ITC, is in agreement with that estimated from the zeta potential (-2.0 M(-1)) at moderate salt concentrations. Our results suggest that hydration dynamics may play a vital role in the membrane solution interface which strongly affects the ion-membrane interaction. PMID:26802251

  19. Multicolour photochromism of colloidal solutions of niobate nanosheets intercalated with several kinds of metal ions.

    PubMed

    Kamada, Kai; Tanaka, Yosuke; Tokunaga, Motoko; Ueda, Taro; Hyodo, Takeo; Shimizu, Yasuhiro

    2016-02-25

    Colourless and transparent colloidal solutions of niobate nanosheets intercalated with some kinds of metal ions (M-NNS, M: metal) showed quasi-reversible photochromism. Ultraviolet light irradiation of the solutions induced a change in color while maintaining the transparency, and the color change was dependent on the metal ions. The coloured solutions were bleached by exposure to an oxidizing atmosphere. This cycle could be repeated several times. PMID:26821602

  20. The Interchangeability of Plasma and Whole Blood Metal Ion Measurement in the Monitoring of Metal on Metal Hips

    PubMed Central

    Malek, Ibrahim A.; Rogers, Joanne; King, Amanda Christina; Clutton, Juliet; Winson, Daniel; John, Alun

    2015-01-01

    One hundred and twenty six paired samples of plasma and whole blood were measured with inductively coupled plasma mass spectrometry technique for metal ions analysis to determine a relationship between them. There was a significant difference between the mean plasma and whole blood concentrations of both cobalt (Co) and chromium (Cr) (p < 0.0001 for both Co and Cr). The mean ratio between plasma and whole blood Cr and Co was 1.56 (range: 0.39–3.85) and 1.54 (range: 0.64–18.26), respectively, but Bland and Altman analysis illustrated that this relationship was not universal throughout the range of concentrations. There was higher variability at high concentrations for both ions. We conclude that both these concentrations should not be used interchangeably and conversion factors are unreliable due to concentration dependent variability. PMID:26798516

  1. Selective retention of basic compounds by metal aquo-ion affinity chromatography.

    PubMed

    Asakawa, Yoshiki; Yamamoto, Eiichi; Asakawa, Naoki

    2014-10-01

    A novel metal aquo-ion affinity chromatography has been developed for the analysis of basic compounds using heat-treated silica gel containing hydrated metal cations (metal aquo-ions) as the packing material. The packing materials of the metal aquo-ion affinity chromatography were prepared by the immobilization of a single metal component such as Fe(III), Al(III), Ag(I), and Ni(II) on silica gel followed by extensive heat treatment. The immobilized metals form aquo-ions to present cation-exchange ability for basic analytes and the cation-exchange ability for basic analytes depends on pKa of the immobilized metal species. In the present study, to evaluate the retention characteristics of metal aquo-ion affinity chromatography, the on-line solid-phase extraction of drugs was investigated. Obtained data clearly evidence the selective retention capability of metal aquo-ion affinity chromatography for basic analytes with sufficient capacity. PMID:25044622

  2. π-Extended dipyrrins capable of highly fluorogenic complexation with metal ions

    PubMed Central

    Filatov, Mikhail A.; Lebedev, Artem Y.; Mukhin, Sergei N.; Vinogradov, Sergei A.; Cheprakov, Andrei V.

    2010-01-01

    Synthesis and properties of a new family of π-extended dipyrrins, capable of forming brightly fluorescent complexes with metal ions, are reported. The metal complexes posses tunable spectral bands and exhibit different emission properties depending on the mode of metal coordination. PMID:20583759

  3. Inhibition of heavy metal ion corrosion on aluminum in fresh water cooling systems using propylene glycol anti-freeze

    SciTech Connect

    Hack, H.P.; Corbett, R.; Krantz, B.

    1998-12-31

    Electronics cooling and environmental control systems are required in enclosed manned spaces such as the inside of spacecraft or submersibles. Because egress from such spaces may not be possible in a short time frame, coolant leaks must have minimum toxicity. For this reason, propylene glycol coolants are preferred over the traditional ethylene glycol coolants. Corrosion inhibitor formulations are well developed for ethylene glycol coolants, but there is concern that the inhibitor suite for propylene glycol systems may not be as mature. In particular, coolant systems with a mixture of aluminum and copper can develop heavy metal ion corrosion of the aluminum due to precipitation of copper ions from solution onto the aluminum. This type of accelerated corrosion of aluminum does not require electrical contact with copper, as is the case for galvanic corrosion, nor is significant coolant conductivity required for corrosion to occur. This paper presents a study of the ability of a commercial inhibited propylene glycol coolant to prevent heavy metal ion corrosion of aluminum when copper is also present in the coolant system. The inhibited propylene glycol`s performance is compared to that of reagent propylene glycol without inhibitors, a mature ethylene glycol inhibited coolant, and to tap water. The inhibitor suite in the inhibited propylene glycol was found to be as effective in controlling heavy metal ion corrosion as that of the inhibited ethylene glycol coolant, while uninhibited reagent propylene glycol was ineffective in controlling heavy metal ion corrosion.

  4. Effect of hydroxyapatite thickness on metal ion release from Ti6Al4V substrates.

    PubMed

    Sousa, S R; Barbosa, M A

    1996-02-01

    The electrochemical dissolution behaviour of Ti6Al4V alloy coated with hydroxyapatite (HA) by plasma spraying was studied in Hank's balanced salt solution (HBSS) and compared with that of polished and grit-blasted passivated surfaces. Two different nominal thicknesses of HA (50 and 200 micro m) were used. Taking a polished passivated surface as reference, grit blasting of the substrate increased the electrical charge used in the oxidation of Ti6Al4V alloy at constant potential, as a result of increased surface area. However, only HA coatings with a thickness of 200 micro m were capable of reducing the charge to values lower than those measured for polished surfaces. Electrochemical impedance spectroscopy has also shown that only 200 micro m thick coatings are effective in reducing the oxidation rate of the substrate. Furthermore, in potentiostatic experiments the 50 micro m thick coating detached from the substrate, which did not occur with the 200 micro m thick coating. However, after 6 months immersion in HBSS, detachment occurred in some regions of both coatings. No titanium, aluminium or vanadium were detected in solution by electrothermal atomic absorption spectroscopy. These data indicate that HA is an effective barrier to metal ion release, even for the thinner coatings, due to formation of metal phosphates or to incorporation of metal ions in the HA structure. PMID:8938233

  5. Effect of large pore size of multifunctional mesoporous microsphere on removal of heavy metal ions.

    PubMed

    Yuan, Qing; Li, Nan; Chi, Yue; Geng, Wangchang; Yan, Wenfu; Zhao, Ying; Li, Xiaotian; Dong, Bin

    2013-06-15

    Pore size of mesoporous materials is crucial for their surface grafting. This article develops a novel multifunctional microsphere with a large pore size mesoporous silica shell (ca. 10.3 nm) and a magnetic core (Fe₃O₄), which is fabricated using cetyltrimethylammonium bromide (CTAB) as pore-forming agents, tetraethyl orthosilicate (TEOS) as silicon source through a sol-gel process. Compared with small pore size mesoporous silica magnetic microspheres (ca. 2-4 nm), the large pore size one can graft 447 mg/g amino groups in order to adsorb more heavy metal ions (Pb(2+): 880.6 mg/g, Cu(2+): 628.3mg/g, Cd(2+): 492.4 mg/g). The metal-loaded multifunctional microspheres could be easily removed from aqueous solution by magnetic separation and regenerated easily by acid treatment. The results suggest that the large pore size multifunctional microspheres are potentially useful materials for high effectively adsorbing and removing different heavy metal ions in aqueous solution. PMID:23618656

  6. Advanced material and approach for metal ions removal from aqueous solutions.

    PubMed

    Turhanen, Petri A; Vepsäläinen, Jouko J; Peräniemi, Sirpa

    2015-01-01

    A Novel approach to remove metals from aqueous solutions has been developed. The method is based on a resin free, solid, non-toxic, microcrystalline bisphosphonate material, which has very low solubility in water (59 mg/l to ion free Milli-Q water and 13 mg/l to 3.5% NaCl solution). The material has been produced almost quantitatively on a 1 kg scale (it has been prepared also on a pilot scale, ca. 7 kg) and tested successfully for its ability to collect metal cations from different sources, such as ground water and mining process waters. Not only was this material highly efficient at collecting several metal ions out of solution it also proved to be regenerable and reusable over a number of adsorption/desorption, which is crucial for environmental friendliness. This material has several advantages compared to the currently used approaches, such as no need for any precipitation step. PMID:25758924

  7. Advanced material and approach for metal ions removal from aqueous solutions

    PubMed Central

    Turhanen, Petri A.; Vepsäläinen, Jouko J.; Peräniemi, Sirpa

    2015-01-01

    A Novel approach to remove metals from aqueous solutions has been developed. The method is based on a resin free, solid, non-toxic, microcrystalline bisphosphonate material, which has very low solubility in water (59 mg/l to ion free Milli-Q water and 13 mg/l to 3.5% NaCl solution). The material has been produced almost quantitatively on a 1 kg scale (it has been prepared also on a pilot scale, ca. 7 kg) and tested successfully for its ability to collect metal cations from different sources, such as ground water and mining process waters. Not only was this material highly efficient at collecting several metal ions out of solution it also proved to be regenerable and reusable over a number of adsorption/desorption, which is crucial for environmental friendliness. This material has several advantages compared to the currently used approaches, such as no need for any precipitation step. PMID:25758924

  8. Metal hydrides used as negative electrode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Sartori, Sabrina; Cuevas, Fermin; Latroche, Michel

    2016-02-01

    Energy is a key issue for future generation. Researches are conducted worldwide to develop new efficient means for energy conversion and storage. Electrochemical storage is foreseen as an efficient way to handle intermittent renewable energy production. The most advanced batteries are nowadays based on lithium-ion technology though their specific capacities should be significantly increased to bring solution to mass storage. Conversion reactions are one way to step forward larger capacities at the anode. We here review the possibility to use metallic or complex hydrides as negative electrode using conversion reaction of hydride with lithium. Moreover, promising alloying of lithium with the metallic species might provide additional reversible capacities. Both binary and ternary systems are reviewed and results are compared in the frame of the electrochemical application.

  9. Metal-Ion Metathesis and Properties of Triarylboron-Functionalized Metal-Organic Frameworks.

    PubMed

    Wang, Xiaoqing; Zhang, Liangliang; Yang, Jie; Dai, Fangna; Wang, Rongming; Sun, Daofeng

    2015-07-01

    An anionic metal-organic framework, H3[(Mn4Cl)3L8]⋅30H2O⋅2.5 DMF⋅5 Diox (UPC-15), was successfully prepared by the reaction of MnCl2 with tris(p-carboxylic acid)tridurylborane (H3 L) under solvothermal conditions. UPC-15 with wide-open pores (∼18.8 Å) is constructed by packing of octahedral and cuboctahedral cages, and exhibits high gas-sorption capabilities. Notably, UPC-15 shows selective adsorption of cationic dyes due to the anion framework. Moreover, the catalytic and magnetic properties were investigated, and UPC-15 can highly catalyze the cyanosilylation of aromatic aldehydes. UPC-15 exhibits the exchange of metal ions from Mn to Cu in a single-crystal-to-single-crystal manner to generate UPC-16, which could not be obtained by the direct solvothermal reaction of CuCl2 and H3L. UPC-16 exhibits similar properties for gas sorption, dye separation, and catalytic activity. However, the magnetic behaviors for UPC-15 and UPC-16 are distinct due to the metal-specific properties. Below 47 K, UPC-15 exhibits a ferromagnetic coupling but UPC-16 shows a dominant antiferromagnetic behavior. PMID:25929722

  10. Influence of Surface Coating on Metal Ion Release: Evaluation in Patients With Metal Allergy.

    PubMed

    Thomas, Peter; Weik, Thomas; Roider, Gabriele; Summer, Burkhard; Thomsen, Marc

    2016-05-01

    Nickel, chromium, and cobalt in stainless steel and Cobalt-chrome-molybdenum (CoCrMo) alloys may induce allergy. The objectives of this study were to evaluate surface coating regarding ion release, patch test reactivity, and arthroplasty performance. Materials and methods included patch test in 31 patients with metal allergy and 30 patients with no allergy to stainless steel and CoCrMo disks that are uncoated or coated by titanium nitride/zirconium nitride (TiN/ZrN). Assessment include atomic absorption spectrometry of released nickel, cobalt, and chromium from the disks after exposure to distilled water, artificial sweat and culture medium. Results showed that both coatings reduced the nickel and chromium release from stainless steel and CoCrMo disks and mostly the cobalt release from the disks (maximally 11.755 µg/cm(2)/5 d to 1.624 by Ti-N and to 0.442 by ZrN). Six of the 31 patients with metal allergy reacted to uncoated disks, but none reacted to the coated disks. The current authors report on exemplary patients with metal allergy who had symptom relief by revision with surface-coated arthroplasty. The authors concluded that the surface coating may prevent cutaneous and peri-implant allergic reactions. [Orthopedics. 2016; 39(3):S24-S30.]. PMID:27219723

  11. Heavy-ion induced electronic desorption of gas from metals

    SciTech Connect

    Molvik, A W; Kollmus, H; Mahner, E; Covo, M K; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Kramer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L

    2006-12-19

    During heavy ion operation in several particle accelerators world-wide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion induced gas desorption scales with the electronic energy loss (dE{sub e}/d/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  12. Computational scheme for the prediction of metal ion binding by a soil fulvic acid

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.; Ephraim, J.H.; Mathuthu, A.S.

    1995-01-01

    The dissociation and metal ion binding properties of a soil fulvic acid have been characterized. Information thus gained was used to compensate for salt and site heterogeneity effects in metal ion complexation by the fulvic acid. An earlier computational scheme has been modified by incorporating an additional step which improves the accuracy of metal ion speciation estimates. An algorithm is employed for the prediction of metal ion binding by organic acid constituents of natural waters (once the organic acid is characterized in terms of functional group identity and abundance). The approach discussed here, currently used with a spreadsheet program on a personal computer, is conceptually envisaged to be compatible with computer programs available for ion binding by inorganic ligands in natural waters.

  13. Metal ion specificities for folding and cleavage activity in the Schistosoma hammerhead ribozyme

    PubMed Central

    Boots, Jennifer L.; Canny, Marella D.; Azimi, Ehsan; Pardi, Arthur

    2008-01-01

    The effects of various metal ions on cleavage activity and global folding have been studied in the extended Schistosoma hammerhead ribozyme. Fluorescence resonance energy transfer was used to probe global folding as a function of various monovalent and divalent metal ions in this ribozyme. The divalent metals ions Ca2+, Mg2+, Mn2+, and Sr2+ have a relatively small variation (less than sixfold) in their ability to globally fold the hammerhead ribozyme, which contrasts with the very large difference (>10,000-fold) in apparent rate constants for cleavage for these divalent metal ions in single-turnover kinetic experiments. There is still a very large range (>4600-fold) in the apparent rate constants for cleavage for these divalent metal ions measured in high salt (2 M NaCl) conditions where the ribozyme is globally folded. These results demonstrate that the identity of the divalent metal ion has little effect on global folding of the Schistosoma hammerhead ribozyme, whereas it has a very large effect on the cleavage kinetics. Mechanisms by which the identity of the divalent metal ion can have such a large effect on cleavage activity in the Schistosoma hammerhead ribozyme are discussed. PMID:18755844

  14. Electric Double-Layer Effects Induce Separation of Aqueous Metal Ions.

    PubMed

    Ji, Qinghua; An, Xiaoqiang; Liu, Huijuan; Guo, Lin; Qu, Jiuhui

    2015-11-24

    Metal ion separation is crucial to environmental decontamination, chromatography, and metal recovery and recycling. Theoretical studies have suggested that the ion distributions in the electric double-layer (EDL) region depend on the nature of the ions and the characteristics of the charged electrode surface. We believe that rational design of the electrode material and device structure will enable EDL-based devices to be utilized in the separation of aqueous metal ions. On the basis of this concept, we fabricate an EDL separation (EDLS) device based on sandwich-structured N-functionalized graphene sheets (CN-GS) for selective separation of aqueous toxic heavy metal ions. We demonstrate that the EDLS enables randomly distributed soluble ions to form a coordination-driven layer and electrostatic-driven layer in the interfacial region of the CN-GS/solution. Through tuning the surface potential of the CN-GS, the effective separation of heavy metal ions (coordination-driven layer) from alkali or alkaline earth metal ions (electrostatic-driven layer) can be achieved. PMID:26481603

  15. Metal ion complexation by ionizable crown ethers. Progress report, January 1, 1991--December 31, 1993

    SciTech Connect

    Bartsch, R.A.

    1993-07-01

    Cyclic and acyclic polyether compounds with pendent carboxylic acid, phosphonic acid monoethyl ester, sulfonic acid, phosphinic acid and hydroxamic acid groups have been synthesized. The proton-ionizable polyethers can come with and without lipophilic groups. Two types of lipophilic di-ionizable lariat ethers have been prepared. Conformations of proton-ionizable lariat ethers have been probed. Competitive alkali metal cation transport by syn-(decyl)dibenzo-16-crown-5-oxyacetic acid and lipophilic proton-ionizable dibenzo lariat ethers in polymer-supported liquid membranes was studied. Complexation of alkali metal cations with ionized lariat ethers was studied. Condensation polymerization of cyclic and acyclic dibenzo polyethers containing pendent mono-ionizable groups with formaldehyde produces novel ion exchange resins with both ion exchange sites for metal ion complexation and polyether binding sites for metal ion recognition. Resins prepared from lariat ether dibenzo phosphonic acid monoethyl esters show strong sorption of divalent heavy metal cations with selectivity for Pb{sup 2+}.

  16. Determination of metal ion concentrations by SERS using 2,2'-bipyridyl complexes.

    PubMed

    Docherty, Julie; Mabbott, Samuel; Smith, W Ewen; Reglinski, John; Faulds, Karen; Davidson, Christine; Graham, Duncan

    2015-10-01

    Surface enhanced Raman scattering (SERS) can generate characteristic spectral "fingerprints" from metal complexes, thus providing the potential for the development of methods of analysis for the identification and quantitation of a range of metal ions in solution. The advantages include sensitivity and the use of one ligand for several metals without the need for a specific chromophore. Aqueous solutions of Fe(II), Ni(II), Zn(II), Cu(II), Cr(III) and Cd(II) in the presence of excess 2,2'-bipyridyl (bipy) were analysed using SERS. Specific marker bands enabled the identification of each metal ion and the limit of detection for each metal ion was estimated. Two of the ions, Zn(II) and Cu(II), could be detected below the World Health Organisation's (WHO) recommended limits for drinking water at levels of 0.22 and 0.6 mg L(-1), respectively. PMID:26312259

  17. Carboxylate Ion Pairing with Alkali-Metal Ions for β-Lactoglobulin and Its Role on Aggregation and Interfacial Adsorption.

    PubMed

    Beierlein, Frank R; Clark, Timothy; Braunschweig, Björn; Engelhardt, Kathrin; Glas, Lena; Peukert, Wolfgang

    2015-04-30

    We report a combined experimental and computational study of the whey protein β-lactoglobulin (BLG) in different electrolyte solutions. Vibrational sum-frequency generation (SFG) and ellipsometry were used to investigate the molecular structure of BLG modified air-water interfaces as a function of LiCl, NaCl, and KCl concentrations. Molecular dynamics (MD) simulations and thermodynamic integration provided details of the ion pairing of protein surface residues with alkali-metal cations. Our results at pH 6.2 indicate that BLG at the air-water interface forms mono- and bilayers preferably at low and high ionic strength, respectively. Results from SFG spectroscopy and ellipsometry are consistent with intimate ion pairing of alkali-metal cations with aspartate and glutamate carboxylates, which is shown to be more effective for smaller cations (Li(+) and Na(+)). MD simulations show not only carboxylate-alkali-metal ion pairs but also ion multiplets with the alkali-metal ion in a bridging position between two or more carboxylates. Consequently, alkali-metal cations can bridge carboxylates not only within a monomer but also between monomers, thus providing an important dimerization mechanism between hydrophilic surface patches. PMID:25825918

  18. Novel Metal Ion Based Estrogen Mimics for Molecular Imaging

    SciTech Connect

    Rajagopalan, Raghavan

    2006-01-30

    The overall objective of the SBIR Phase I proposal is to prepare and evaluate a new class of {sup 99m}Tc or {sup 94m}Tc containing estrogen-like small molecules ('estrogen mimics') for SPECT or PET molecular imaging of estrogen receptor positive (ER+) tumors. In this approach, the metal ion is integrated into the estrone skeleton by isosteric substitution of a carbon atom in the steroidal structure to give new class of mimics that are topologically similar to the native estrogen (Fig. 1). Although both N{sub 2}S{sub 2} and N{sub 3}S mimics 1 and 2 were considered as target structures, molecular modeling study revealed that the presence of the acetyl group at position-15 in the N{sub 3}S mimic 2 causes steric hinderance toward binding of 2 to SHBG. Therefore, initial efforts were directed at the synthesis and evaluation of the N{sub 2}S{sub 2} mimic 1.

  19. Regulation of the divalent metal ion transporter via membrane budding

    PubMed Central

    Mackenzie, KimberlyD; Foot, Natalie J; Anand, Sushma; Dalton, Hazel E; Chaudhary, Natasha; Collins, Brett M; Mathivanan, Suresh; Kumar, Sharad

    2016-01-01

    The release of extracellular vesicles (EVs) is important for both normal physiology and disease. However, a basic understanding of the targeting of EV cargoes, composition and mechanism of release is lacking. Here we present evidence that the divalent metal ion transporter (DMT1) is unexpectedly regulated through release in EVs. This process involves the Nedd4-2 ubiquitin ligase, and the adaptor proteins Arrdc1 and Arrdc4 via different budding mechanisms. We show that mouse gut explants release endogenous DMT1 in EVs. Although we observed no change in the relative amount of DMT1 released in EVs from gut explants in Arrdc1 or Arrdc4 deficient mice, the extent of EVs released was significantly reduced indicating an adaptor role in biogenesis. Furthermore, using Arrdc1 or Arrdc4 knockout mouse embryonic fibroblasts, we show that both Arrdc1 and Arrdc4 are non-redundant positive regulators of EV release. Our results suggest that DMT1 release from the plasma membrane into EVs may represent a novel mechanism for the maintenance of iron homeostasis, which may also be important for the regulation of other membrane proteins. PMID:27462458

  20. Interaction between ATP, metal ions, glycine, and several minerals

    NASA Technical Reports Server (NTRS)

    Rishpon, J.; Ohara, P. J.; Lawless, J. G.; Lahav, N.

    1982-01-01

    Interactions between ATP, glycine and montmorillonite and kaolinite clay minerals in the presence of various metal cations are investigated. The adsorption of adenine nucleotides on clays and Al(OH)3 was measured as a function of pH, and glycine condensation was followed in the presence of ATP, ZnCl2, MgCl2 and either kaolinite or montmorillonite. The amounts of ATP and ADP adsorbed are found to decrease with increasing Ph, and to be considerably enhanced in experiments with Mg(2+)- and Zn(2+)-montmorillonite with respect to Na(+)-montmorillonite. The effects of divalent cations are less marked in kaolinite. Results for Al(OH)3 show the importance of adsorption at clay platelet edges at high pH. The decomposition of ATP during drying at high temperature is observed to be inhibited by small amounts of clay, vacuum, or Mg(2+) or Zn(2+) ions, and to be accompanied by peptide formation in the presence of glycine. Results suggest the importance of Zn(2+) and Mg(2+) in chemical evolution.

  1. Structures and energetics of complexation of metal ions with ammonia, water, and benzene: A computational study.

    PubMed

    Sharma, Bhaskar; Neela, Y Indra; Narahari Sastry, G

    2016-04-30

    Quantum chemical calculations have been performed at CCSD(T)/def2-TZVP level to investigate the strength and nature of interactions of ammonia (NH3 ), water (H2 O), and benzene (C6 H6 ) with various metal ions and validated with the available experimental results. For all the considered metal ions, a preference for C6 H6 is observed for dicationic ions whereas the monocationic ions prefer to bind with NH3 . Density Functional Theory-Symmetry Adapted Perturbation Theory (DFT-SAPT) analysis has been employed at PBE0AC/def2-TZVP level on these complexes (closed shell), to understand the various energy terms contributing to binding energy (BE). The DFT-SAPT result shows that for the metal ion complexes with H2 O electrostatic component is the major contributor to the BE whereas, for C6 H6 complexes polarization component is dominant, except in the case of alkali metal ion complexes. However, in case of NH3 complexes, electrostatic component is dominant for s-block metal ions, whereas, for the d and p-block metal ion complexes both electrostatic and polarization components are important. The geometry (M(+) -N and M(+) -O distance for NH3 and H2 O complexes respectively, and cation-π distance for C6 H6 complexes) for the alkali and alkaline earth metal ion complexes increases down the group. Natural population analysis performed on NH3 , H2 O, and C6 H6 complexes shows that the charge transfer to metal ions is higher in case of C6 H6 complexes. PMID:26833683

  2. The calculation of electron chemical potential and ion charge state and their influence on plasma conductivity in electrical explosion of metal wire

    SciTech Connect

    Shi, Zongqian; Wang, Kun; Li, Yao; Shi, Yuanjie; Wu, Jian; Jia, Shenli

    2014-03-15

    The electron chemical potential and ion charge state (average ion charge and ion distribution) are important parameters in calculating plasma conductivity in electrical explosion of metal wire. In this paper, the calculating method of electron chemical potential and ion charge state is discussed at first. For the calculation of electron chemical potential, the ideal free electron gas model and Thomas-Fermi model are compared and analyzed in terms of the coupling constant of plasma. The Thomas-Fermi ionization model, which is used to calculate ion charge state, is compared with the method based on Saha equation. Furthermore, the influence of electron degenerated energy levels and ion excited states in Saha equation on the ion charge state is also analyzed. Then the influence of different calculating methods of electron chemical potential and ion charge state on plasma conductivity is discussed by applying them in the Lee-More conductivity model.

  3. Microstructural development due to long-term aging and ion irradiation behavior in weld metals of austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Nakata, K.; Ikeda, S.; Hamada, S.; Hishinuma, A.

    1996-10-01

    In a candidate austenitic stainless steel (316F) for fusion reactor structural materials, irradiation behavior of the weld metal produced by electron-beam welding (containing 7.9 vol% δ-ferrite) was investigated in terms of microstructural development. The densities of interstitial clusters in the γ-phase of the weld metal irradiated with He-ions at 673 and 773 K were about four times larger than those in 316F. Voids were formed in the δ-ferrite of the weld irradiated at 773 K. The number of clusters decreased in the weld metal (γ-phase) aged at 773 to 973 K, compared with that in the as-welded metal. The change in cluster density could be attributed to a Ni concentration increase in the γ-phase of the weld metal during aging.

  4. Effect of acetabular cup design on metal ion release in two designs of metal-on-metal hip resurfacing.

    PubMed

    Cadossi, Matteo; Tedesco, Giuseppe; Savarino, Lucia; Baldini, Nicola; Mazzotti, Antonio; Greco, Michelina; Giannini, Sandro

    2014-10-01

    The purpose of this observational prospective cohort study was to evaluate the serum concentrations of cobalt (Co), chromium (Cr), and nickel (Ni) at a 2-year follow-up in patients operated on with a novel design of hip resurfacing: Romax resurfacing system (RRS). RRS is characterized by the presence of an acetabular notch which theoretically provides a wider range of motion and a reduced incidence of groin pain. The presence of radiolucencies and functional outcome, assessed using the Harris hip score (HHS) and the University of California Activity scale (UCLA), were secondary endpoints. Moreover, these results were compared with those obtained in our previous study from a similar cohort of patients implanted using the Birmingham Hip Resurfacing (BHR) system. At a 2-year follow-up, the serum levels of Co in patients operated on using the RRS were five times higher (p = 0.0002) than those found before surgery (Co, means: 1.04 and 0.20 ng/mL, respectively); similarly, Cr levels were 13 times higher (p < 0.0001) at a 2-year follow-up than before surgery (Cr, means: 1.69 and 0.13 ng/mL, respectively). Ni concentrations (0.42 and 0.78 ng/mL) were not significantly different (p = 0.16), even if they increased 86% after surgery. In the RRS patients, an inverse correlation was found between Co and Cr concentrations and length of follow-up (Co: r = -0.64, p = 0.0096; Cr: r= -0.45, p = 0.08). The serum levels of Co and Cr were not significantly different between RRS (Co: 1.04 ng/mL and Cr: 1.69 ng/mL) and BHR (Co: 1.39 ng/mL and Cr: 2.30 ng/mL) patients at 2 years (p = 0.95 and 0.26 for Co and Cr, respectively). Our results showed that RRS patients achieved an excellent clinical outcome with limited metal ion release. PMID:24962936

  5. Injection of metallic elements into an electron-beam ion trap using a Knudsen cell

    SciTech Connect

    Yamada, C.; Nagata, K.; Nakamura, N.; Ohtani, S.; Takahashi, S.; Tobiyama, T.; Tona, M.; Watanabe, H.; Yoshiyasu, N.; Sakurai, M.; Kavanagh, A. P.; Currell, F. J.

    2006-06-15

    A method of injecting metallic elements into an electron-beam ion trap (EBIT) is described. The method is advantageous over the conventional coaxial and pulsed injection methods in two ways: (a) complicated switching of injection and extraction beams can be avoided when extracting beams of highly charged ions from the EBIT and (b) a beam of stable intensity can be achieved. This method may be applicable to any metallic elements or metallic compounds that have vapor pressures of {approx}0.1 Pa at a temperature lower than 1900 deg. C. We have employed this method for the extraction of highly charged ions of Bi, Er, Fe, and Ho.

  6. Determination of metal ions by fluorescence anisotropy exhibits a broad dynamic range

    NASA Astrophysics Data System (ADS)

    Thompson, Richard B.; Maliwal, Badri P.; Fierke, Carol A.

    1998-05-01

    Recently, we have shown that metal ions free in solution may be determined at low levels by fluorescence anisotropy (polarization) measurements. Anisotropy measurements enjoy the advantages of wavelength ratiometric techniques for determining metal ions such as calcium, because anisotropy measurements are ratiometric as well. Furthermore, fluorescence anisotropy may be imaged in the microscope. An advantage of anisotropy not demonstrated for wavelength ratiometric approaches using indicators such as Fura-2 and Indo-1 is that under favorable circumstances anisotropy-based determinations exhibit a much broader dynamic range in metal ion concentration. Determinations of free Zn(II) in the picomolar range are demonstrated.

  7. Sono-electrochemical recovery of metal ions from their aqueous solutions.

    PubMed

    Dong, Bingfeng; Fishgold, Asher; Lee, Paul; Runge, Keith; Deymier, Pierre; Keswani, Manish

    2016-11-15

    Metal recovery from aqueous waste streams is an important goal for recycling, agriculture and mining industries. The development of more effective methods of recovery have been of increasing interest. The most common methods for metal recovery include precipitation, electrochemical, ion exchange, flocculation/coagulation and filtration. In the current work, a sono-electrochemical technique employing sound field at megasonic frequency (500kHz or 1MHz) in conjunction with electrochemistry is evaluated for enhanced recovery of selected metal ions (palladium, lead and gallium) with different redox potentials from their aqueous solutions. The surface morphology and elemental composition of the metal deposits were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The percent recovery was found to depend on the type of metal ion and the megasonic frequency used. Palladium was recovered in its metal form, while lead and gallium were oxidized during or after the recovery process. PMID:27450329

  8. Revising secondary electron yields of ion-sputtered metal oxides

    NASA Astrophysics Data System (ADS)

    Corbella, Carles; Marcak, Adrian; de los Arcos, Teresa; von Keudell, Achim

    2016-04-01

    The emission of secondary electrons (SE) during sputtering of Al and Ti foils by argon ions in an oxygen background has been measured in a particle beam reactor equipped with a SE-collector. This experiment mimics the process of reactive magnetron sputtering. Quantified beams of argon ions with energies between 500 eV and 2000 eV were employed, while simultaneously molecular oxygen fluxes impinged on the surface and caused oxidation. The measured secondary electron emission coefficients (γ) ranged from approximately 0.1 (for clean aluminium and titanium) to 1.2 and 0.6 (in the case of aluminium oxide and titanium oxide, respectively). The increase of γ is compared to SE measurements based on the modelling of magnetron plasmas. Moreover, the energy distributions of the emitted SE have been measured by varying the retarding potential of the SE-collector, which allows the monitoring of the oxidation state from the position of the Auger peaks. The origin of the observed SE yields based on the emission of low- and high-energy electrons generated on the oxide surface is discussed.

  9. Cytotoxicity of Metal Ions Released from Nitinol Alloys on Endothelial Cells

    NASA Astrophysics Data System (ADS)

    Haider, W.; Munroe, N.; Tek, V.; Gill, P. K. S.; Tang, Y.; McGoron, A. J.

    2011-07-01

    Most implantable medical devices are expected to function in the body over an extended period of time. Therefore, immersion tests under simulated conditions can be useful for assessing the amount of metal ions released in situ. In this investigation, dissolved ions from as-received binary and ternary Nitinol alloys in cell culture media were periodically measured under static and dynamic conditions. Endothelial cells were grown in aliquots of culture media obtained and the effect of dissolved ions on cell proliferation and viability of endothelial cells (HUVEC) was studied by cytotoxicity assays. The concentration of metal ions in the media was measured by inductively coupled plasma mass spectrometry.

  10. Damage calculation in fusion ceramics: comparing neutrons and light ions

    NASA Astrophysics Data System (ADS)

    Vladimirov, P. V.; Lizunov, D.; Ryazanov, Yu. A. I.; Möslang, A.

    1998-03-01

    A method developed earlier for displacement damage calculations in compound materials is applied to fusion ceramics irradiated by various neutron sources and light ion accelerators. For protons up to 40 MeV and alpha-particles up to 100 MeV, as well as for several neutron environments (EEF, ITER, HFIR, FFTF), sublattice-specific primary recoil spectra and displacement damage rates have been calculated for α-Al 2O 3, AlN, BeO, MgO, MgAl 2O 4 and SiC. Although the primary recoil spectra can vary significantly for different neutron sources and light ions, the ratios of sublattice-specific damage rates are the same within 5% for BeO, MgO and SiC in all considered environments. For ceramics containing Al, the damage ratio differs up to about 40% between neutron and light ion irradiations.

  11. Plastic flow produced by single ion impacts on metals.

    SciTech Connect

    Birtcher, R. C.

    1998-10-30

    Single ion impacts have been observed using in situ transmission electron microscopy and video recording with a time resolution of 33 milliseconds. Gold was irradiated at 50 K and room temperature. Single ion impacts produce holes, modify existing holes, and extrude material into the initial specimen hole and holes formed by other ion impacts. The same behavior is observed at both temperatures. At both temperatures, ion impacts result in craters and ejected material. Ion impacts produce more small craters than large ones for all ion masses, while heavier mass ions produce more and larger craters than lighter mass ions. This comparison is affected by the ion energy. As the energy of an ion is increased, the probability for deposition near the surface decreases and fewer craters are formed. For a given ion mass, crater production depends on the probability for displacement cascade production in the near surface region. Crater and holes are stable at room temperature, however, ion impacts near an existing crater may cause flow of material into the crater either reshaping or annihilating it. Holes and craters result from the explosive outflow of material from the molten zone of near-surface cascades. The outflow may take the form of molten material, a solid lid or an ejected particle. The surface is a major perturbation on displacement cascades resulting from ion impacts.

  12. Gas-phase chemistry of transition-metal ions with alkanes: do initial electrostatic interaction control final product distributions

    SciTech Connect

    Hankinson, D.J.; Allison, J.

    1987-09-24

    There are features of the dynamics of gas-phase ion/molecule reactions that make them unique when compared to neutral/neutral reactions and solution processes. Exceedingly rich and complex chemistry can be observed in gas-phase systems in which a reactant is charged, due, in part, to the relatively long lifetime of the ion/molecule complex that is initially formed. Here possible correlations between final reaction products and geometry-specific complexes that are initially formed are discussed. The chemistry under study is that for univalent first-row transition-metal ions with n-butane, in which cleavage of C-H and C-C bonds is observed for some metals.

  13. Equilibrium studies on tetracycline-metal ion systems.

    PubMed

    Novák-Pékli, M; el-Hadi Mesbah, M; Pethó, G

    1996-06-01

    Protonation and equilibrium constant for oxytetracycline (OTC) and doxycycline (DOX) with Zn2+, Ca2+ and Mg2+ ions have been determined with Calvin-type pH-metric titrations under physiological conditions (37 degrees C, 0.15 M NaCl ionic strength). Even though OTC and DOX are similar in structure, major differences were found in complex composition with regard to the protonation state: OTC generally formed species with less protons compared to those with DOX. Studies of parent complexes were followed by investigations of ternary complexes where ascorbic acid was used as a secondary ligand. Again, OTC showed a tendency to form complexes in which fewer protons are bound than in those with DOX. This equilibrium difference between OTC and DOX might be because DOX has a better pharmacodynamic effect relative to that of OTC. PMID:8818010

  14. Metal ion levels and functional results after either resurfacing hip arthroplasty or conventional metal-on-metal hip arthroplasty

    PubMed Central

    2011-01-01

    Background Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potentially increased metal ion release. Patients and methods 71 patients (< 65 years old) were randomly assigned to receive either a resurfacing (R) hip arthroplasty (n = 38) or a conventional metal-on-metal (C) hip arthroplasty (n = 33). Functional outcomes were assessed preoperatively and at 6, 12, and 24 months. Cobalt and chromium blood levels were analyzed preoperatively and at 3, 6, 12, and 24 months. Results All functional outcome scores improved for both groups. At 12 and 24 months, the median UCLA activity score was 8 in the R patients and 7 in the C patients (p < 0.05). At 24 months, OHS was median 16 in C patients and 13 in R patients (p < 0.05). However, in spite of randomization, UCLA scores also appeared to be higher in R patients at baseline. Satisfaction was similar in both groups at 24 months. Cobalt concentrations were statistically significantly higher for R patients only at 3 and 6 months. Chromium levels remained significantly higher for R patients until 24 months. No pseudotumors were encountered in either group. One R patient was revised for early aseptic loosening and in 2 C patients a cup insert was exchanged for recurrent dislocation. Interpretation R patients scored higher on UCLA, OHS, and satisfaction at some time points; however, as for the UCLA, preoperative levels were already in favor of R. The differences, although statistically significant, were of minor clinical importance. Chromium blood levels were statistically significantly higher for R patients at all follow-up measurements, whereas for cobalt this was only observed up to 6 months. The true value of resurfacing hip arthroplasty over conventional metal-on-metal hip arthroplasty will be determined by longer follow-up and a possible shift of balance between their

  15. Perforated Metal Oxide-Carbon Nanotube Composite Microspheres with Enhanced Lithium-Ion Storage Properties.

    PubMed

    Choi, Seung Ho; Lee, Jong-Heun; Kang, Yun Chan

    2015-10-27

    Metal oxide-carbon nanotube (CNT) composite microspheres with a novel structure were fabricated using a one-step spray pyrolysis process. Metal oxide-CNT composite microspheres with a uniform distribution of void nanospheres were prepared from a colloidal spray solution containing CNTs, metal salts, and polystyrene (PS) nanobeads. Perforated SnO2-CNT composite microspheres with a uniform distribution of void nanospheres showed excellent lithium storage properties as anode materials for lithium-ion batteries. Bare SnO2 microspheres and SnO2-CNT composite microspheres with perforated and filled structures had a discharge capacity of 450, 1108, and 590 mA h g(-1) for the 250th cycle at a current density of 1.5 A g(-1), and the corresponding capacity retention compared to the second cycle was 41, 98, and 55%, respectively. The synergetic combination of void nanospheres and flexible CNTs improved the electrochemical properties of SnO2. This effective and innovative strategy could be used for the preparation of perforated metal oxide-CNT composites with complex elemental compositions for many applications. PMID:26355350

  16. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrations in an urban estuary.

    PubMed

    Dong, Zhao; Lewis, Christopher G; Burgess, Robert M; Coull, Brent; Shine, James P

    2016-05-01

    Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limited, due to underexplored techniques for measuring multiple free metal ions simultaneously. In this work, we performed statistical analyses on a large dataset containing repeated measurements of free ion concentrations of Cu, Zn, Pb, Ni, and Cd, the most commonly measured metals in seawater, at five inshore locations in Boston Harbor, previously collected using an in-situ equilibrium-based multi-metal free ion sampler, the 'Gellyfish'. We examined correlations among these five metals by season, and evaluated effects of 10 biogeochemical variables on free ion concentrations over time and location through multivariate regressions. We also explored potential clustering among the five metals through a principal component analysis. We found significant correlations among metals, with varying patterns over season. Our regression results suggest that instead of dissolved metals, pH, salinity, temperature and rainfall were the most significant determinants of free metal ion concentrations. For example, a one-unit decrease in pH was associated with a 2.2 (Cd) to 99 (Cu) times increase in free ion concentrations. This work is among the first to reveal key contributors to spatiotemporal variations in free ion concentrations, and demonstrated the usefulness of the Gellyfish sampler in routine sampling of free ions within metal mixtures and in generating data for statistical analyses. PMID:26901477

  17. Biosorption of heavy metal ions to brown algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida

    SciTech Connect

    Seki, Hideshi; Suzuki, Akira

    1998-10-01

    A fundamental study of the application of brown algae to the aqueous-phase separation of toxic heavy metals was carried out. The biosorption characteristics of cadmium and lead ions were determined with brown algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida. A metal binding model proposed by the authors was used for the description of metal binding data. The results showed that the biosorption of bivalent metal ions to brown algae was due to bivalent binding to carboxylic groups on alginic acid in brown algae.

  18. Visualizing metal ions in cells: an overview of analytical techniques, approaches, and probes

    PubMed Central

    Dean, Kevin M.; Qin, Yan; Palmer, Amy E.

    2012-01-01

    Quantifying the amount and defining the location of metal ions in cells and organisms are critical steps in understanding metal homeostasis and how dyshomeostasis causes or is a consequence of disease. A number of recent advances have been made in the development and application of analytical methods to visualize metal ions in biological specimens. Here, we briefly summarize these advances before focusing in more depth on probes for examining transition metals in living cells with high spatial and temporal resolution using fluorescence microscopy. PMID:22521452

  19. Method and apparatus for providing negative ions of actinide-metal hexafluorides

    DOEpatents

    Compton, Robert N.; Reinhardt, Paul W.; Garrett, William R.

    1978-01-01

    This invention relates to a novel method and a novel generator, or source, for providing gaseous negative ions of selected metal hexafluorides. The method is summarized as follows: in an evacuated zone, reacting gaseous fluorine with an actinide-metal body selected from the group consisting of uranium, plutonium, neptunium, and americium to convert at least part of the metal to the hexafluoride state, thus producing gaseous negatively charged metal-hexafluoride ions in the evacuated zone, and applying an electric field to the zone to remove the ions therefrom. The ion source comprises a chamber defining a reaction zone; means for evacuating the zone; an actinide-metal body in the zone, the metal being uranium, plutonium, neptunium, or americium; means for contacting the body with gaseous fluorine to convert at least a part thereof to the hexafluoride state; and means for applying an electric field to the evacuated zone to extract gaseous, negatively charged metal-hexafluoride ions therefrom. The invention provides unique advantages over conventional surface-ionization techniques for producing such ions.

  20. Cooperative adsorption of critical metal ions using archaeal poly-γ-glutamate.

    PubMed

    Hakumai, Yuichi; Oike, Shota; Shibata, Yuka; Ashiuchi, Makoto

    2016-06-01

    Antimony, beryllium, chromium, cobalt (Co), gallium (Ga), germanium, indium (In), lithium, niobium, tantalum, the platinoids, the rare-earth elements (including dysprosium, Dy), and tungsten are generally regarded to be critical (rare) metals, and the ions of some of these metals are stabilized in acidic solutions. We examined the adsorption capacities of three water-soluble functional polymers, namely archaeal poly-γ-glutamate (L-PGA), polyacrylate (PAC), and polyvinyl alcohol (PVA), for six valuable metal ions (Co(2+), Ni(2+), Mn(2+), Ga(3+), In(3+), and Dy(3+)). All three polymers showed apparently little or no capacity for divalent cations, whereas L-PGA and PAC showed the potential to adsorb trivalent cations, implying the beneficial valence-dependent selectivity of anionic polyelectrolytes with multiple carboxylates for metal ions. PVA did not adsorb metal ions, indicating that the crucial role played by carboxyl groups in the adsorption of crucial metal ions cannot be replaced by hydroxyl groups under the conditions. In addition, equilibrium studies using the non-ideal competitive adsorption model indicated that the potential for L-PGA to be used for the removal (or collection) of water-soluble critical metal ions (e.g., Ga(3+), In(3+), and Dy(3+)) was far superior to that of any other industrially-versatile PAC materials. PMID:27013333

  1. Hybrid gas-metal co-implantation with a modified vacuum arc ion source

    SciTech Connect

    Oks, E.M.; Yushkov, G.Y.; Evans, P.J.; Oztarhan, A.; Brown, I.G.; Dickinson, M.R.; Liu, F.; MacGill, R.A.; Monteiro, O.R.; Wang, Z.

    1996-08-01

    Energetic beams of mixed metal and gaseous ion species can be generated with a vacuum arc ion source by adding gas to the arc discharge region. This could be an important tool for ion implantation research by providing a method for forming buried layers of mixed composition such as e.g. metal oxides and nitrides. In work to date, we have formed a number of mixed metal-gas ion beams including Ti+N, Pt+N, Al+O, and Zr+O. The particle current fractions of the metal-gas ion components in the beam ranged from 100% metallic to about 80% gaseous, depending on operational parameters. We have used this new variant of the vacuum arc ion source to carry out some exploratory studies of the effect of Al+O and Zr+O co-implantation on tribology of stainless steel. Here we describe the ion source modifications, species and charge state of the hybrid beams produced, and results of preliminary studies of surface modification of stainless steel by co-implantation of mixed Al/O or Zr/O ion beams. 5 figs, 21 refs.

  2. Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue

    DOEpatents

    Sharp, David W.

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about 249.degree. F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  3. Importance of diffuse metal ion binding to RNA.

    PubMed

    Tan, Zhi-Jie; Chen, Shi-Jie

    2011-01-01

    RNAs are highly charged polyanionic molecules. RNA structure and function are strongly correlated with the ionic condition of the solution. The primary focus of this article is on the role of diffusive ions in RNA folding. Due to the long-range nature of electrostatic interactions, the diffuse ions can contribute significantly to RNA structural stability and folding kinetics. We present an overview of the experimental findings as well as the theoretical developments on the diffuse ion effects in RNA folding. This review places heavy emphasis on the effect of magnesium ions. Magnesium ions play a highly efficient role in stabilizing RNA tertiary structures and promoting tertiary structural folding. The highly efficient role goes beyond the mean-field effect such as the ionic strength. In addition to the effects of specific ion binding and ion dehydration, ion-ion correlation for the diffuse ions can contribute to the efficient role of the multivalent ions such as the magnesium ions in RNA folding. PMID:22010269

  4. How Cation-Pi Interactions Enhance and Structure the Binding of Metal Ions to Amino Acids and Peptides. Dialanine Probed by Irmpd Spectroscopy as a Prime Example

    NASA Astrophysics Data System (ADS)

    Dunbar, Robert C.; Steill, Jeffrey; Oomens, Jos

    2010-06-01

    Spectroscopic examination of metalated amino acids and model peptides in the infrared region gives incisive conformational information. The role of cation-pi interactions of the metal ions with aromatic amino acids in structuring the complexes and enforcing particular architectures is being clarified by such experiments using IRMPD action spectroscopy as the experimental probe. The presence of multiple aromatic groups as in dialanine gives particularly stringent conformational stabilization. Comparing spectroscopic peak shifts across a range of alkali and alkaline earth metal ions, ranging from lithium to cesium, and from calcium to barium, allows us to view the systematic relations between normal mode frequencies and ion/peptide interactions. The spectra of the ions were acquired by irradiating the cell of the Fourier-transform ion cyclotron resonance mass spectrometer with infrared light from the FELIX free electron laser at wavelengths in the approximate range 500 to 1900 cm-1.

  5. Negative ion production by backscattering from alkali-metal surfaces bombarded by ions of hydrogen and deuterium

    SciTech Connect

    Schneider, P.J.

    1980-03-01

    Measurements have been made of the total backscattered D/sup -/ and H/sup -/ yields from thick, clean targets of Cs, Rb, K, Na, and Li, bombarded with H/sub 2//sup +/, H/sub 3//sup +/, D/sub 2//sup +/, and D/sub 3//sup +/ with incident energies from 0.15 to 4.0 keV/nucleus. All of the measurements were made at background pressures less than 10/sup -9/ Torr and the alkali-metal targets were evaporated onto a cold substrate (T = 77K) in situ to assure thick, uncontaminated targets. Measurements of the H/sup -/ yield from various transition metal targets with thin coverages of alkali-metals have also been made as a function of the surface work function. The negative ion yields are discussed in terms of the probabilities of reflection of the incident particles, of formation of the negative ion at the surface and of the survival of the negative ion leaving the surface. For each thick alkali-metal target, the negative ion yield measurements have been used in a least squares fit to determine two parameters in a theoretically derived expression for the negative ion yield. The parameters obtained from a thick Na target have been used to calculate the yield from a Cu target with thin coverage of Na (such that the surface work function is equal to thick Na).

  6. Adsorptions of some heavy metal ions in aqueous solutions by acrylamide/maleic acid hydrogels

    SciTech Connect

    Saraydin, D.; Karadag, E.; Gueven, O.

    1995-10-01

    In this study, acrylamide-maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by {gamma}-radiation. They have been used for adsorption of some heavy metal ions such as uranium, iron, and copper. For the hydrogel containing 40 mg of maleic acid and irradiated at 3.73 kGy, maximum and minimum swellings in the aqueous solutions of the heavy metal ions have been observed with water (1480%) and the aqueous solution of iron(III) nitrate (410%), respectively. Diffusions of water and heavy metal ions onto hydrogels have been found to be of the non-Fickian type of diffusion. In experiments of uranyl ions adsorption, Type II adsorption has been found. One gram of AAa/MA hydrogels sorbed 14-86 mg uranyl ions from solutions of uranyl acetate, 14-90 mg uranyl ions from solutions of uranyl nitrate, 16-39 mg iron ions from solutions of iron(IV) nitrate, and 28-81 mg copper ions from solutions of copper acetate, while acrylamide hydrogel did not sorb any heavy metals ions.

  7. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    SciTech Connect

    Lu, Yi

    2005-06-01

    In vitro selection for DNAzymes that are catalytically active with UO22+ ions as the metal cofactor has been completed. The 10th generation pool of DNA was cloned and sequenced. A total of 84 clones were sequenced and placed into families based on sequence alignments. Selected members of each family were 5-labeled with 32P and amplified using PCR. Activity assays were conducted using the isotopically labeled DNAzymes in order to determine which sequences were the most active. The secondary structures of the two most active sequences, called Clone 13 and Clone 39, were determined using the computer program Mfold. A cleavage rate of approximately 1 min-1 in the presence of 10 uM UO22+ was observed for both clones. Clone 39 was determined to be the best candidate for truncation to create a trans-cleaving DNAzyme, based on its secondary structure. An enzyme strand, called 39E, and a substrate strand, called 39DS, were designed by truncating the cis-cleaving DNAzyme. An alternative enzyme strand, called 39Ec, was also assayed with the 39DS substrate. This strand was designed so that the two binding arms were perfectly complimentary, unlike 39E, which formed three mismatched base pairs with 39DS. Both 39E and 39Ec were found to be active, with a rate of approximately 1 min-1 in the presence of 10 uM UO22+. A preliminary UO22+ binding curve was obtained for the 39Ec/39DS trans-cleaving system. The enzyme is active with UO22+ concentrations as low as 1 nM. Based on the preliminary binding curve data, the apparent UO22+ binding constant is approximately 330 nM, and kmax is approximately 1 min-1.

  8. Requirement for transient metal ions revealed through computational analysis for DNA polymerase going in reverse

    PubMed Central

    Perera, Lalith; Freudenthal, Bret D.; Beard, William A.; Shock, David D.; Pedersen, Lee G.; Wilson, Samuel H.

    2015-01-01

    DNA polymerases facilitate faithful insertion of nucleotides, a central reaction occurring during DNA replication and repair. DNA synthesis (forward reaction) is “balanced,” as dictated by the chemical equilibrium by the reverse reaction of pyrophosphorolysis. Two closely spaced divalent metal ions (catalytic and nucleotide-binding metals) provide the scaffold for these reactions. The catalytic metal lowers the pKa of O3′ of the growing primer terminus, and the nucleotide-binding metal facilitates substrate binding. Recent time-lapse crystallographic studies of DNA polymerases have identified an additional metal ion (product metal) associated with pyrophosphate formation, leading to the suggestion of its possible involvement in the reverse reaction. Here, we establish a rationale for a role of the product metal using quantum mechanical/molecular mechanical calculations of the reverse reaction in the confines of the DNA polymerase β active site. Additionally, site-directed mutagenesis identifies essential residues and metal-binding sites necessary for pyrophosphorolysis. The results indicate that the catalytic metal site must be occupied by a magnesium ion for pyrophosphorolysis to occur. Critically, the product metal site is occupied by a magnesium ion early in the pyrophosphorolysis reaction path but must be removed later. The proposed dynamic nature of the active site metal ions is consistent with crystallographic structures. The transition barrier for pyrophosphorolysis was estimated to be significantly higher than that for the forward reaction, consistent with kinetic activity measurements of the respective reactions. These observations provide a framework to understand how ions and active site changes could modulate the internal chemical equilibrium of a reaction that is central to genome stability. PMID:26351676

  9. Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

    NASA Astrophysics Data System (ADS)

    Duncan, Michael

    2006-03-01

    Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

  10. Electronic states of M-DNA incorporated with divalent metal ions

    NASA Astrophysics Data System (ADS)

    Mizoguchi, Kenji

    2010-08-01

    DNA has attracted much interest as a material for nano science and technology. To unveil the intrinsic nature of DNA both in natural form and modified forms of M-DNA with a variety of divalent metal ions. From the magnetic and optical properties, it is concluded that the electronic states of natural salmon DNA is of semiconducting. Thus, only the hopping transport via excited states or impurity site like oxygens is expected. One of the efforts to introduce charge carriers into DNA, insertion of divalent metal ions, has been studied from magnetic, optical and structural aspects. It was concluded that the divalent metal ions are inserted in between the bases of a base pair, in place of hydrogen bonds, and the charge transfer from the metal ions to DNA occurs only in the case of Fe-DNA.

  11. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-01

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

  12. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma

    SciTech Connect

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-15

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

  13. Fast esterification of spent grain for enhanced heavy metal ions adsorption.

    PubMed

    Li, Qingzhu; Chai, Liyuan; Wang, Qingwei; Yang, Zhihui; Yan, Huxiang; Wang, Yunyan

    2010-05-01

    This work describes a novel method for fast esterification of spent grain to enhance its cationic adsorption capacity. The esterification of spent grain with citric acid was achieved by using sodium hypophosphite monohydrate (NaH(2)PO(2).H(2)O) as a catalyst in N,N-dimethylformamide (DMF). Fourier transform infrared (FTIR) spectroscopic analysis revealed the formation of ester groups after esterification, demonstrating that spent grain was successfully esterified with citric acid. The adsorption capacity of esterified spent grain (ESG) for each metal ion was greatly improved as compared with that of raw spent grain (RSG). Typically, Pb(2+) adsorption capacity increased from 125.84mg g(-1) of RSG to 293.30mg g(-1) of ESG. This increase can be attributed to both the formation of ester linkage and the grafting of carboxyl groups on spent grain. The results suggest that a fast process for esterification of spent grain has been realized and ESG has strong ability to adsorb heavy metal ions. PMID:20110169

  14. Modeling of the association of metal ions with heterogeneous environmental sorbents

    SciTech Connect

    Westall, J.C.

    1995-12-31

    The use of mechanistic (surface-complexation, electric-double layer) and semi-empirical (affinity spectrum) models for representation of the association of metal ions with heterogeneous environmental materials, such as humic acids and soil particle surfaces, is compared. It is seen that mechanistic models are not nearly as mechanistic as one generally assumes, and that semi-empirical models are much more valuable than one might assume by comparison to simple K{sub d} models. A semi-empirical discrete-log-K-spectrum model was used to describe the binding of Co(II), as a function of pH and NaClO{sub 4} concentration, to two environmental substrates: leonardite humic acid and a kaolinitic subsoil. Excellent agreement of the model and the data was obtained over a wide range of solution composition. These models appear to be the most promising among several alternatives for modeling interactions of metal ions with complex heterogeneous environmental materials over a wide range of solution composition. 38 refs., 4 figs., 2 tabs.

  15. High-energy metal ion implantation for reduction of surface resistivity of alumina ceramica)

    NASA Astrophysics Data System (ADS)

    Gushenets, V. I.; Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.; Brown, I. G.

    2012-02-01

    In this work, the possibility to increase the surface conductivity of ceramic insulators through their treatment with accelerated metal ion beams produced by a MevvaV.Ru vacuum arc source is demonstrated. The increase in surface conductivity is made possible due to experimental conditions in which an insulated collector is charged by beam ions to a potential many times lower than the accelerating voltage, and hence, than the average beam ion energy. The observed effect of charge neutralization of the accelerated ion beam is presumably associated with electrons knocked out of the electrodes of the accelerating system of the source and of the walls of the vacuum chamber by the accelerated ions.

  16. Characteristics of flows of energetic atoms reflected from metal targets during ion bombardment

    NASA Astrophysics Data System (ADS)

    Kuzmichev, A.; Perevertaylo, V.; Tsybulsky, L.; Volpian, O.

    2016-07-01

    Particle number and energy reflection coefficients for energetic neutralized gas ions (Ar and O atoms) backscattered from metal targets during ion bombardment have been calculated using TRIM code. The energy distributions of reflected atoms are computed, too, and their dependence on the primary ion energy and the angle of ion incidence is determined. The obtained data confirm the possibility of employing energetic atoms reflection for generation of high energy neutral beams and point out to take this phenomenon into account under analysis of the ion technology for coating deposition.

  17. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

    2015-12-01

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)-based metal-organic frameworks, Zn3L3(DMF)2 (1) and Zn3L3(DMA)2(H2O)3 (2) (L=4,4‧-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe3+ and Al3+ by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe3+. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity.

  18. The abilities of selenium dioxide and selenite ion to coordinate DNA-bound metal ions and decrease oxidative DNA damage.

    PubMed

    Hart, William E; Marczak, Steven P; Kneller, Andrew R; French, Robert A; Morris, Daniel L

    2013-08-01

    Several transition metals react with H2O2 and produce reactive oxygen species (ROS) responsible for oxidative damage linked to many diseases and disorders, and species that form coordination complexes with these metal ions show promise as antioxidants. The present study demonstrates that metal-mediated radical and non-radical oxidative DNA damage decreases when selenium dioxide (SeO2) and sodium selenite (Na2SeO3) are present. Radical-induced damage is associated with production of 8-hydroxy-2'-deoxyguanosine (8-OH-dG), which arises from ROS generated at or near the guanine base, and the selenium compounds reduce Fe(II)-, Cr(III)- and Cu(II)-mediated radical damage to differing degrees based on the identity of the metal ion and the order in which the metals, selenium compounds and DNA are combined. Radical damage arising from Fe(II) and Cr(III) decreases substantially when they are pre-incubated with the selenium compounds prior to adding DNA. Non-radical damage is associated with oxidation of the adenine base in the presence of high H2O2 concentrations through an ionic mechanism, and this type of damage also decreases significantly when the selenium compounds are allowed to interact with the metal ions before adding DNA. Fluorescence studies using dihydrodichlorofluorescein diacetate (DCF-DA) to probe ROS formation indicate that the majority of the SeO2- and SeO3(2-)-metal systems in combination with H2O2 (no DNA present) produce ROS to the same degree as the metal/H2O2 systems in the absence of the selenium compounds, suggesting that selenium-metal complexes react with H2O2 in a sacrificial manner that protects DNA from oxidative damage. PMID:23628661

  19. Biosorption of heavy metal ions from aqueous solution by red macroalgae.

    PubMed

    Ibrahim, Wael M

    2011-09-15

    Biosorption is an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine algae has been reported to have high biosorption capacities for a number of heavy metal ions. In this study, four species of red seaweeds Corallina mediterranea, Galaxaura oblongata, Jania rubens and Pterocladia capillacea were examined to remove Co(II), Cd(II), Cr(III) and Pb(II) ions from aqueous solution. The experimental parameters that affect the biosorption process such as pH, contact time and biomass dosage were studied. The maximum biosorption capacity of metal ions was 105.2mg/g at biomass dosage 10 g/L, pH 5 and contact time 60 min. The biosorption efficiency of algal biomass for the removal of heavy metal ions from industrial wastewater was evaluated for two successive cycles. Galaxaura oblongata biomass was relatively more efficient to remove metal ions with mean biosorption efficiency of 84%. This study demonstrated that these seaweeds constitute a promising, efficient, cheap and biodegradable sorbent biomaterial for lowering the heavy metal pollution in the environment. PMID:21798665

  20. A new paradigm of DNA synthesis: three-metal-ion catalysis.

    PubMed

    Yang, Wei; Weng, Peter J; Gao, Yang

    2016-01-01

    Enzyme catalysis has been studied for over a century. How it actually occurs has not been visualized until recently. By combining in crystallo reaction and X-ray diffraction analysis of reaction intermediates, we have obtained unprecedented atomic details of the DNA synthesis process. Contrary to the established theory that enzyme-substrate complexes and transition states have identical atomic composition and catalysis occurs by the two-metal-ion mechanism, we have discovered that an additional divalent cation has to be captured en route to product formation. Unlike the canonical two metal ions, which are coordinated by DNA polymerases, this third metal ion is free of enzyme coordination. Its location between the α- and β-phosphates of dNTP suggests that the third metal ion may drive the phosphoryltransfer from the leaving group opposite to the 3'-OH nucleophile. Experimental data indicate that binding of the third metal ion may be the rate-limiting step in DNA synthesis and the free energy associated with the metal-ion binding can overcome the activation barrier to the DNA synthesis reaction. PMID:27602203

  1. Highly selective monitoring of metals by using ion-imprinted polymers.

    PubMed

    Hande, Pankaj E; Samui, Asit B; Kulkarni, Prashant S

    2015-05-01

    Ion imprinting technology is one of the most promising tools in separation and purification sciences because of its high selectivity, good stability, simplicity and low cost. It has been mainly used for selective removal, preconcentration, sensing and few miscellaneous fields. In this review article, recent methodologies in the synthesis of IIPs have been discussed. For several applications, different parameters of IIP including complexing and leaching agent, pH, relative selectivity coefficient, detection limit and adsorption capacity have been evaluated and an attempt has been made to generalize. Biomedical applications mostly include selective removal of toxic metals from human blood plasma and urine samples. Wastewater treatment involves selective removal of highly toxic metal ions like Hg(II), Pb(II), Cd(II), As(V), etc. Preconcentration covers recovery of economically important metal ions such as gold, silver, platinum and palladium. It also includes selective preconcentration of lanthanides and actinides. In sensing, various IIP-based sensors have been fabricated for detection of toxic metal ions. This review article includes almost all metal ions based on the ion-imprinted polymer. At the end, the future outlook section presents the discussion on the advancement, corresponding merits and the need of continued research in few specific areas. Graphical Abstract IIPs for the selective monitoring of metals. PMID:25663338

  2. Effects of mono- and divalent metal ions on DNA binding and catalysis of human apurinic/apyrimidinic endonuclease 1.

    PubMed

    Miroshnikova, Anastasia D; Kuznetsova, Alexandra A; Vorobjev, Yuri N; Kuznetsov, Nikita A; Fedorova, Olga S

    2016-05-26

    Here, we used stopped-flow fluorescence techniques to conduct a comparative kinetic analysis of the conformational transitions in human apurinic/apyrimidinic endonuclease 1 (APE1) and in DNA containing an abasic site in the course of their interaction. Effects of monovalent (K(+)) and divalent (Mg(2+), Mn(2+), Ca(2+), Zn(2+), Cu(2+), and Ni(2+)) metal ions on DNA binding and catalytic stages were studied. It was shown that the first step of substrate binding (corresponding to formation of a primary enzyme-substrate complex) does not depend on the concentration (0.05-5.0 mM) or the nature of divalent metal ions. In contrast, the initial DNA binding efficiency significantly decreased at a high concentration (5-250 mM) of monovalent K(+) ions, indicating the involvement of electrostatic interactions in this stage. It was also shown that Cu(2+) ions abrogated the DNA binding ability of APE1, possibly, due to a strong interaction with DNA bases and the sugar-phosphate backbone. In the case of Ca(2+) ions, the catalytic activity of APE1 was lost completely with retention of binding potential. Thus, the enzymatic activity of APE1 is increased in the order Zn(2+) < Ni(2+) < Mn(2+) < Mg(2+). Circular dichroism spectra and calculation of the contact area between APE1 and DNA reveal that Mg(2+) ions stabilize the protein structure and the enzyme-substrate complex. PMID:27063150

  3. The catalytic role of the M2 metal ion in PP2Cα

    NASA Astrophysics Data System (ADS)

    Pan, Chang; Tang, Jun-Yi; Xu, Yun-Fei; Xiao, Peng; Liu, Hong-Da; Wang, Hao-An; Wang, Wen-Bo; Meng, Fan-Guo; Yu, Xiao; Sun, Jin-Peng

    2015-02-01

    PP2C family phosphatases (the type 2C family of protein phosphatases; or metal-dependent phosphatase, PPM) constitute an important class of signaling enzymes that regulate many fundamental life activities. All PP2C family members have a conserved binuclear metal ion active center that is essential for their catalysis. However, the catalytic role of each metal ion during catalysis remains elusive. In this study, we discovered that mutations in the structurally buried D38 residue of PP2Cα (PPM1A) redefined the water-mediated hydrogen network in the active site and selectively disrupted M2 metal ion binding. Using the D38A and D38K mutations of PP2Cα as specific tools in combination with enzymology analysis, our results demonstrated that the M2 metal ion determines the rate-limiting step of substrate hydrolysis, participates in dianion substrate binding and stabilizes the leaving group after P-O bond cleavage. The newly characterized catalytic role of the M2 metal ion in this family not only provides insight into how the binuclear metal centers of the PP2C phosphatases are organized for efficient catalysis but also helps increase our understanding of the function and substrate specificity of PP2C family members.

  4. The catalytic role of the M2 metal ion in PP2Cα.

    PubMed

    Pan, Chang; Tang, Jun-yi; Xu, Yun-fei; Xiao, Peng; Liu, Hong-da; Wang, Hao-an; Wang, Wen-bo; Meng, Fan-guo; Yu, Xiao; Sun, Jin-peng

    2015-01-01

    PP2C family phosphatases (the type 2C family of protein phosphatases; or metal-dependent phosphatase, PPM) constitute an important class of signaling enzymes that regulate many fundamental life activities. All PP2C family members have a conserved binuclear metal ion active center that is essential for their catalysis. However, the catalytic role of each metal ion during catalysis remains elusive. In this study, we discovered that mutations in the structurally buried D38 residue of PP2Cα (PPM1A) redefined the water-mediated hydrogen network in the active site and selectively disrupted M2 metal ion binding. Using the D38A and D38K mutations of PP2Cα as specific tools in combination with enzymology analysis, our results demonstrated that the M2 metal ion determines the rate-limiting step of substrate hydrolysis, participates in dianion substrate binding and stabilizes the leaving group after P-O bond cleavage. The newly characterized catalytic role of the M2 metal ion in this family not only provides insight into how the binuclear metal centers of the PP2C phosphatases are organized for efficient catalysis but also helps increase our understanding of the function and substrate specificity of PP2C family members. PMID:25708299

  5. Sodium ion diffusion in Al2O3: a distinct perspective compared with lithium ion diffusion.

    PubMed

    Jung, Sung Chul; Kim, Hyung-Jin; Choi, Jang Wook; Han, Young-Kyu

    2014-11-12

    Surface coating of active materials has been one of the most effective strategies to mitigate undesirable side reactions and thereby improve the overall battery performance. In this direction, aluminum oxide (Al2O3) is one of the most widely adopted coating materials due to its easy synthesis and low material cost. Nevertheless, the effect of Al2O3 coating on carrier ion diffusion has been investigated mainly for Li ion batteries, and the corresponding understanding for emerging Na ion batteries is currently missing. Using ab initio molecular dynamics calculations, herein, we first find that, unlike lithiation, sodiation of Al2O3 is thermodynamically unfavorable. Nonetheless, there can still exist a threshold in the Na ion content in Al2O3 before further diffusion into the adjacent active material, delivering a new insight that both thermodynamics and kinetics should be taken into account to describe ionic diffusion in any material media. Furthermore, Na ion diffusivity in NaxAl2O3 turns out to be much higher than Li ion diffusivity in LixAl2O3, a result opposite to the conventional stereotype based on the atomic radius consideration. While hopping between the O-rich trapping sites via an Na-O bond breaking/making process is identified as the main Na ion diffusion mechanism, the weaker Na-O bond strength than the Li-O counterpart turns out to be the origin of the superior diffusivity of Na ions. PMID:25286155

  6. Ion exchange during heavy metal bio-sorption from aqueous solution by dried biomass of macrophytes.

    PubMed

    Verma, V K; Tewari, Saumyata; Rai, J P N

    2008-04-01

    In this study, potentials of oven dried biomass of Eichhornia crassipes, Valisneria spiralis and Pistia stratiotes, were examined in terms of their heavy metal (Cd, Ni, Zn, Cu, Cr and Pb) sorption capacity, from individual-metal and multi-metal aqueous solutions at pH 6.0+/-0.1 (a popular pH of industrial effluent). V. spiralis was the most and E. crassipes was the least efficient for removal of all the metals. Cd, Pb and Zn were efficiently removed by all the three biomass. Cd was removed up to 98% by V. spiralis. Sorption data for Cr, Ni and Cd fitted better to Langmuir isotherm equation, while, the sorption data for Pb, Zn and Cu fitted better to Freundlich isotherm equation. In general, the presence of other metal ions did not influence significantly the targeted metal sorption capacity of the test plant biomasses. Ion exchange was proven the main mechanism involved in bio-sorption and there was a strong ionic balance between adsorbed (H(+) and M(2+)) to the released ions (Na(+) and K(+)) to and from the biomass. No significant difference was observed in the metal exchanged amount, by doubling of metal concentration (15-30 mg/l) in the solution and employing individual-metal and multi-metal solutions. PMID:17513104

  7. Property enchancement of polyimide films by way of the incorporation of lanthanide metal ions

    NASA Technical Reports Server (NTRS)

    Thompson, David W.

    1993-01-01

    Lanthanide metal ions were incorporated into the polyimide derived from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 1,3-bis(aminophenoxy) benzene (APB) in an attempt to produce molecular level metal-polymer composites. The lanthanide series of metal ions (including aluminum, scandium, and yttrium) provide discrete and stable metal ions in the 3+ oxidation state. Throughout the series there is a uniform variation in ionic size ranging from 50 pm for aluminum to a maximum of 103.4 pm for cerium and gradually decreasing again to 84.8 pm for lutetium. The high charge-to-size ratio for these ions as well as the ability to obtain large coordination numbers makes them excellent candidates for interacting with the polymer substructure. The distinct lack of solubility of simple lanthanide salts such as the acetates and halides has made it difficult to obtain metal ions distributed in the polymer framework as discrete ions or metal complexes rather than microcomposites of metal clusters. (Lanthanum nitrates are quite soluble, but the presence of the strongly oxidizing nitrate ion leads to serious degradation of the polymer upon thermal curing. This work was successful at extending the range of soluble metals salts by using chelating agents derived from the beta-diketones dipivaloylmethane, dibenzoylmethane, trifluoroacetylacetone, and hexafluoroacetylacetone. Metal acetates which are insoluble in dimethylacetamide dissolve readily in the presence of the diketones. Addition of the polyimide yields a homogeneous resin which is then cast into a clear film. Upon curing clear films were obtained with the dibenzoylmethane and trifluoroacetylacetone ligands. The dipavaloylmethane precipitates the metal during the film casting process, and hexafluoroacetylacetone gives cured films which are deformed and brittle. These clear films are being evaluated for the effect of the metal ions on the coefficient of thermal expansion, resistance to atomic oxygen, and on

  8. Comparative study of the tritium distribution in metals

    NASA Astrophysics Data System (ADS)

    Perevezentsev, A. N.; Bell, A. C.; Rivkis, L. A.; Filin, V. M.; Gushin, V. V.; Belyakov, M. I.; Bulkin, V. I.; Kravchenko, I. M.; Ionessian, I. A.; Torikai, Y.; Matsuyama, M.; Watanabe, K.; Markin, A. I.

    2008-01-01

    Coupons of stainless steel, Inconel, beryllium, copper and aluminium bronze were exposed to tritium in hydrogen gas mixtures over a wide range of parameters: temperature up to 770 K, pressure from 1 × 10 -4 MPa to 0.05 MPa, tritium concentration from 1 at.% to 98 at.%. The tritium concentration on the surface and distribution through the metals were measured using radiography, radioluminography, β-ray induced X-ray spectroscopy and acid etching methods. The effect of metal processing, such as forging, polishing and heat treatment on the tritium distribution was studied along with parameters relating to the exposure of the metal to tritium.

  9. Application of mucilage from Dicerocaryum eriocarpum plant as biosorption medium in the removal of selected heavy metal ions.

    PubMed

    Jones, Bassey O; John, Odiyo O; Luke, Chimuka; Ochieng, Aoyi; Bassey, Bridget J

    2016-07-15

    The ability of mucilage from Dicerocaryum eriocarpum (DE) plant to act as biosorption medium in the removal of metals ions from aqueous solution was investigated. Functional groups present in the mucilage were identified using Fourier transform infrared spectroscopy (FTIR). Mucilage was modified with sodium and potassium chlorides. This was aimed at assessing the biosorption efficiency of modified mucilage: potassium mucilage (PCE) and sodium mucilage (SCE) and comparing it with non-modified deionised water mucilage (DCE) in the uptake of metal ions. FTIR results showed that the functional groups providing the active sites in PCE and SCE and DCE include: carboxyl, hydroxyl and carbonyl groups. The chloride used in the modification of the mucilage did not introduce new functional groups but increased the intensity of the already existing functional groups in the mucilage. Results from biosorption experiment showed that DE mucilage displays good binding affinity with metals ions [Zn(II), Cd(II) Ni(II), Cr(III) and Fe(II)] in the aqueous solution. Increase in the aqueous solution pH, metal ions initial concentration and mucilage concentration increased the biosorption efficiency of DE mucilage. The maximum contact time varied with each species of metal ions. Optimum pH for [Zn(II), Cd(II) Ni(II) and Fe(II)] occurred at pH 4 and pH 6 for Cr(III). Kinetic models result fitted well to pseudo-second-order with a coefficient values of R(2) = 1 for Cd(II), Ni(II), Cr(III), Fe(II) and R(2) = 0.9974 for Zn(II). Biosorption isotherms conforms best with Freundlich model for all the metal ions with correlation factors of 0.9994, 0.9987, 0.9554, 0.9621 and 0.937 for Zn(II), Ni(II), Fe(II), Cr(III) and Cd(II), respectively. Biosorption capacity of DE mucilage was 0.010, 2.387, 4.902, 0688 and 0.125 for Zn(II), Cr(III), Fe(II), Cd(II) and Ni(II) respectively. The modified mucilage was found to be highly efficient in the removal of metal ions than the unmodified mucilage. PMID

  10. Binding of transition metal ions [cobalt, copper, nickel and zinc] with furanyl-, thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-derived cephalexins as potent antibacterial agents.

    PubMed

    Chohan, Zahid H; Pervez, Humayun; Khan, Khalid Mohammed; Rauf, A; Supuran, Claudiu T

    2004-02-01

    A method is described for the preparation of novel cephalexin-derived furanyl-, thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-containing compounds showing potent antibacterial activity. The binding of these newly synthesized antibacterial agents with metal ions such as cobalt(II), copper(II), nickel(II) and zinc(II) has been studied and their inhibitory properties against various bacterial species such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae are also reported. These results suggest that metal ions to possess an important role in the designing of metal-based antibacterials and that such complexes are more effective against infectious diseases compared to the uncomplexed drugs. PMID:15202493

  11. SUMMARY REPORT: CONTROL AND TREATMENT TECHNOLOGY FOR THE METAL FINISHING INDUSTRY: ION EXCHANGE

    EPA Science Inventory

    This Technology Transfer ummary Report is one of a series of reports that summarizes a pollution control technology for the metal finishing industry. he 45-page report is intended to promote an understanding of the use of ion exchange in the metal finishing industry. The sections...

  12. Density functional study of isoguanine tetrad and pentad sandwich complexes with alkali metal ions.

    PubMed

    Meyer, Michael; Steinke, Thomas; Sühnel, Jürgen

    2007-02-01

    Isoguanine tetraplexes and pentaplexes contain two or more stacked polyads with intercalating metal ions. We report here the results of a density functional study of sandwiched isoguanine tetrad and pentad complexes consisting of two polyads with Na(+), K(+) and Rb(+) ions at the B3LYP level. In comparison to single polyad metal ion complexes, there is a trend towards increased non-planarity of the polyads in the sandwich complexes. In general, the pentad sandwiches have relatively planar polyad structures, whereas the tetrad complexes contain highly non-planar polyad building blocks. As in other sandwich complexes and in metal ion complexes with single polyads, the metal ion-base interaction energy plays an essential role. In iG sandwich structures, this interaction energy is slightly larger than in the corresponding guanine sandwich complexes. Because the base-base interaction energy is even more increased in passing from guanine to isoguanine, the isoguanine sandwiches are thus far the only examples where the base-base interaction energy is larger than the base-metal ion interaction energy. Stacking interactions have been studied in smaller models consisting of two bases, retaining the geometry from the complete complex structures. From the data obtained at the B3LYP and BH&H levels and with Møller-Plesset perturbation theory, one can conclude that the B3LYP method overestimates the repulsion in stacked base dimers. For the complexes studied in this work, this is only of minor importance because the direct inter-tetrad or inter-pentad interaction is supplemented by a strong metal ion-base interaction. Using a microsolvation model, the metal ion preference K(+) approximately Rb(+) > Na(+) is found for tetrad complexes. On the other hand, for pentads the ordering is Rb(+) > K(+) > Na(+). In the latter case experimental data are available that agree with this prediction. PMID:17013632

  13. Supersaturating silicon with transition metals by ion implantation and pulsed laser melting

    SciTech Connect

    Recht, Daniel; Aziz, Michael J.; Smith, Matthew J.; Gradečak, Silvija; Charnvanichborikarn, Supakit; Williams, James S.; Sullivan, Joseph T.; Winkler, Mark T.; Buonassisi, Tonio; Mathews, Jay; Warrender, Jeffrey M.

    2013-09-28

    We investigate the possibility of creating an intermediate band semiconductor by supersaturating Si with a range of transition metals (Au, Co, Cr, Cu, Fe, Pd, Pt, W, and Zn) using ion implantation followed by pulsed laser melting (PLM). Structural characterization shows evidence of either surface segregation or cellular breakdown in all transition metals investigated, preventing the formation of high supersaturations. However, concentration-depth profiling reveals that regions of Si supersaturated with Au and Zn are formed below the regions of cellular breakdown. Fits to the concentration-depth profile are used to estimate the diffusive speeds, v{sub D,} of Au and Zn, and put lower bounds on v{sub D} of the other metals ranging from 10{sup 2} to 10{sup 4} m/s. Knowledge of v{sub D} is used to tailor the irradiation conditions and synthesize single-crystal Si supersaturated with 10{sup 19} Au/cm{sup 3} without cellular breakdown. Values of v{sub D} are compared to those for other elements in Si. Two independent thermophysical properties, the solute diffusivity at the melting temperature, D{sub s}(T{sub m}), and the equilibrium partition coefficient, k{sub e}, are shown to simultaneously affect v{sub D}. We demonstrate a correlation between v{sub D} and the ratio D{sub s}(T{sub m})/k{sub e}{sup 0.67}, which is exhibited for Group III, IV, and V solutes but not for the transition metals investigated. Nevertheless, comparison with experimental results suggests that D{sub s}(T{sub m})/k{sub e}{sup 0.67} might serve as a metric for evaluating the potential to supersaturate Si with transition metals by PLM.

  14. Supersaturating silicon with transition metals by ion implantation and pulsed laser melting

    NASA Astrophysics Data System (ADS)

    Recht, Daniel; Smith, Matthew J.; Charnvanichborikarn, Supakit; Sullivan, Joseph T.; Winkler, Mark T.; Mathews, Jay; Warrender, Jeffrey M.; Buonassisi, Tonio; Williams, James S.; Gradečak, Silvija; Aziz, Michael J.

    2013-09-01

    We investigate the possibility of creating an intermediate band semiconductor by supersaturating Si with a range of transition metals (Au, Co, Cr, Cu, Fe, Pd, Pt, W, and Zn) using ion implantation followed by pulsed laser melting (PLM). Structural characterization shows evidence of either surface segregation or cellular breakdown in all transition metals investigated, preventing the formation of high supersaturations. However, concentration-depth profiling reveals that regions of Si supersaturated with Au and Zn are formed below the regions of cellular breakdown. Fits to the concentration-depth profile are used to estimate the diffusive speeds, vD, of Au and Zn, and put lower bounds on vD of the other metals ranging from 102 to 104 m/s. Knowledge of vD is used to tailor the irradiation conditions and synthesize single-crystal Si supersaturated with 1019 Au/cm3 without cellular breakdown. Values of vD are compared to those for other elements in Si. Two independent thermophysical properties, the solute diffusivity at the melting temperature, Ds(Tm), and the equilibrium partition coefficient, ke, are shown to simultaneously affect vD. We demonstrate a correlation between vD and the ratio Ds(Tm)/ke0.67, which is exhibited for Group III, IV, and V solutes but not for the transition metals investigated. Nevertheless, comparison with experimental results suggests that Ds(Tm)/ke0.67 might serve as a metric for evaluating the potential to supersaturate Si with transition metals by PLM.

  15. A comparative topological study of different metal-metal and metal-ligand interactions in polynuclear organometallic clusters

    SciTech Connect

    Van der Maelen, Juan F.; García-Granda, Santiago

    2015-01-22

    The existence and characterization of a bond between the Zn atoms in the recently synthesized complex [Zn{sub 2}(η{sup 5}−C{sub 5}Me{sub 5}){sub 2}] (I), as well as between two of the three Ru atoms in [Ru{sub 3}(μ−H){sub 2}(μ{sub 3}−MeImCH)(CO{sub 9}] (Me{sub 2}Im = 1,3-dimethylimidazolin-2-ylidene) (II), are firmly based on low temperature X-ray synchrotron diffraction experiments. The multipolar refinement of the experimental electron densities and their topological analyses by means of the Atoms in Molecules (AIM) theory reveal the details of the Zn-Zn and Ru-Ru bonds, such as their open-shell intermediate character. The results are consistent with a typical metal-metal single σ bond for the former, whereas a delocalized kind of bond involving 5c-6e is present in the latter. In addition, experimental results are compared with theoretical ab initio calculations of the DFT (density functional theory) and MP2 (Mo/ller-Plesset perturbation theory) electron densities, giving a coherent view of the bonding in both complexes. Many other topological properties of both compounds are also studied, in particular the different metal-ligand interactions.

  16. Reconsideration of metal surface sputtering due to bombardment of high-energy argon ion particles: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Kammara, Kishore K.; Kumar, Rakesh; Donbosco, Ferdin S.

    2016-03-01

    Some interesting aspects of metal surface sputtering phenomenon are numerically investigated in this work using the molecular dynamics approach. Along with that, we have carried out a critical analysis of the interaction potentials typically used for modeling. Two metallic surfaces, viz., copper, Cu(100), and nickel, Ni(100), are chosen for study that are bombarded by argon ions at various energies and angles of projection. The sputtering yield is calculated by performing molecular dynamics simulations, and the same is compared with experiments and theoretical predictions wherever possible. Furthermore, other interesting parameters like the kinetic energy, velocity, and scattering angle distribution for sputtered and incident atoms are presented and discussed. Through different case studies, the present work emphasizes on the importance of interaction model used for metal surface modeling for a realistic numerical reproduction of the complex metal surface sputtering process.

  17. Comparative toxicity of hypochlorous acid and hypochlorite ions to mosquitofish

    SciTech Connect

    Mattice, J.S.; Tsai, S.C.; Burch, M.B.

    1981-07-01

    We examined the relative toxicity of hypochlorous acid (HOCl) and the hypochlorite ion (OCl/sup -/) by exposing mosquitofish Gambusia affinis for 1 hour to predominantly free residual chlorine (FRC) at six levels of pH following a 7-day acclimation to the test pH. Median lethal concentrations (LC50), in terms of total residual chlorine (TRC), increased with increasing pH. Because of the influence of hydrogen ion concentration on dissociation of HOCl, the percent of FRC present as HOCl is about 97% and 13%, respectively, at the low and high pH. Cursory examination of toxicity of monochloramine (NH/sub 2/Cl) and mixtures of NH/sub 2/Cl and dichloramine (NHCl/sub 2/) suggested that their contributions to toxicity were negligible at any test pH. Free residual chlorine concentrations at the LC50 for each pH were fitted to a theoretical model derived from an assumption that toxicities of HOCl and OCl/sup -/ were additive.

  18. The effect of metal ions on Staphylococcus aureus revealed by biochemical and mass spectrometric analyses.

    PubMed

    Chudobova, Dagmar; Dostalova, Simona; Ruttkay-Nedecky, Branislav; Guran, Roman; Rodrigo, Miguel Angel Merlos; Tmejova, Katerina; Krizkova, Sona; Zitka, Ondrej; Adam, Vojtech; Kizek, Rene

    2015-01-01

    In this study, we focused on the effect of heavy metal ions in resistant strains of gram-positive bacteria Staphylococcus aureus using biochemical methods and mass spectrometry. Five nitrate solutions of heavy metals (Ag(+), Cu(2+), Cd(2+), Zn(2+) and Pb(2+)) were used to create S. aureus resistant strains. Biochemical changes of resistant strains in comparison with the non-resistant control strain of S. aureus were observed by microbiological (measuring - growth curves and inhibition zones) and spectrophotometric methods (antioxidant activity and alaninaminotransferase, aspartateaminotransferase, alkaline phosphatase, γ-glutamyltransferase activities). Mass spectrometry was employed for the qualitative analysis of the samples (changes in S. aureus protein composition) and for the identification of the strains database MALDI Biotyper was employed. Alterations, in terms of biochemical properties and protein composition, were observed in resistant strains compared to non-resistant control strain. Our results describe the possible option for the analysis of S. aureus resistant strains and may thus serve as a support for monitoring of changes in genetic information caused by the forming of resistance to heavy metals. PMID:25189671

  19. Inhibition of transcription factor IIIA-DNA interactions by xenobiotic metal ions.

    PubMed

    Hanas, J S; Gunn, C G

    1996-03-01

    Transcription factor IIIA (TFIIIA), a cysteine-rich regulatory protein, is the prototype for the largest known superfamily of eukaryotic transcription factors. Members of the TFIIIA superfamily contain Cys2His2 zinc finger domains responsible for nucleic acid binding. Xenobiotic metal ions, which lack known biological function, were previously used as probes for the structure and function of steroid hormone receptors which contain Cys2Cys2 zinc finger domains. Structural alterations in cysteine-rich regulatory proteins by such ions in vivo might potentiate carcinogenesis and other disease processes. In the present study cadmium and other xenobiotic metal ions were used to probe the structure and function of TFIIIA. The specific interaction of TFIIIA with the internal control region (ICR) of the 5S RNA gene, as assayed by DNase I protection, was inhibited by Cd2+ ion concentrations of > or = 0.1 microM. Aluminum ions were also found to inhibit the TFIIIA-5S RNA gene interaction, albeit at higher concentrations (> or = 5 microM). Inhibition by either metal ion was not readily reversible. Other xenobiotic metal ions, such as mercury or cesium, were not found to be inhibitory under these conditions. None of these ions at the concentrations used in this study affected the ability of DNase I to digest DNA or restriction enzymes to specifically cleave DNA. Preincubation of TFIIIA bound to 5S RNA with either Cd2+ or Al3+ resulted in subsequent DNA binding upon dilution and RNA removal, whereas preincubation of free TFIIIA with the metal ions resulted in inhibition of subsequent DNA binding. Because 5S rRNA also binds the TFIIIA zinc finger domains, these results indicate that the 5S RNA bound to TFIIIA protects the protein from metal inhibition and implicates the zinc fingers in the inhibition mechanism. The nature of the footprint inhibition indicates that the N-terminal fingers of TFIIIA are affected by the metal ions. Cd2+ and Al3+ ions also inhibited the ability of

  20. Generation of reactive oxygen species by interaction between antioxidants used as food additive and metal ions.

    PubMed

    Iwasaki, Yusuke; Oda, Momoko; Tsukuda, Yuri; Nagamori, Yuki; Nakazawa, Hiroyuki; Ito, Rie; Saito, Koichi

    2014-01-01

    Food additives, such as preservatives, sweeteners, coloring agents, and flavoring agents, are widely used in food manufacturing. However, their combined effects on the human body are not known. The purpose of this study was to examine whether combinations of antioxidants and metal ions generate reactive oxygen species (ROS) under in vitro conditions using electron spin resonance (ESR). Among the metal ions examined, only iron and copper generated ROS in the presence of antioxidants. Moreover, certain phenolic antioxidants having pro-oxidant activity induced DNA oxidation and degradation via the generation of high levels of ROS in the presence of copper ion, resulting in complete degradation of DNA in vitro. PMID:25212818

  1. Inhibition of transcription factor IIIA-DNA interactions by xenobiotic metal ions.

    PubMed Central

    Hanas, J S; Gunn, C G

    1996-01-01

    Transcription factor IIIA (TFIIIA), a cysteine-rich regulatory protein, is the prototype for the largest known superfamily of eukaryotic transcription factors. Members of the TFIIIA superfamily contain Cys2His2 zinc finger domains responsible for nucleic acid binding. Xenobiotic metal ions, which lack known biological function, were previously used as probes for the structure and function of steroid hormone receptors which contain Cys2Cys2 zinc finger domains. Structural alterations in cysteine-rich regulatory proteins by such ions in vivo might potentiate carcinogenesis and other disease processes. In the present study cadmium and other xenobiotic metal ions were used to probe the structure and function of TFIIIA. The specific interaction of TFIIIA with the internal control region (ICR) of the 5S RNA gene, as assayed by DNase I protection, was inhibited by Cd2+ ion concentrations of > or = 0.1 microM. Aluminum ions were also found to inhibit the TFIIIA-5S RNA gene interaction, albeit at higher concentrations (> or = 5 microM). Inhibition by either metal ion was not readily reversible. Other xenobiotic metal ions, such as mercury or cesium, were not found to be inhibitory under these conditions. None of these ions at the concentrations used in this study affected the ability of DNase I to digest DNA or restriction enzymes to specifically cleave DNA. Preincubation of TFIIIA bound to 5S RNA with either Cd2+ or Al3+ resulted in subsequent DNA binding upon dilution and RNA removal, whereas preincubation of free TFIIIA with the metal ions resulted in inhibition of subsequent DNA binding. Because 5S rRNA also binds the TFIIIA zinc finger domains, these results indicate that the 5S RNA bound to TFIIIA protects the protein from metal inhibition and implicates the zinc fingers in the inhibition mechanism. The nature of the footprint inhibition indicates that the N-terminal fingers of TFIIIA are affected by the metal ions. Cd2+ and Al3+ ions also inhibited the ability of

  2. Adherence of ion beam sputter deposited metal films on H-13 steel

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.

    1980-01-01

    An electron bombardment argon ion source was used to sputter deposit 17 different metal and metal oxide films ranging in thickness from 1 to 8 micrometers on H-13 steel substrates. The film adherence to the substrate surface was measured using a tensile test apparatus. Comparisons in bond strength were made between ion beam, ion plating, and RF deposited films. A protective coating to prevent heat checking in H-13 steel dies used for aluminum die casting was studied. The results of exposing the coated substrates to temperatures up to 700 degrees are presented.

  3. Ion chromatographic determination of transition metals in irradiated nuclear reactor surveillance samples.

    PubMed

    Louw, I

    1996-02-01

    The determination of transition metal ions in radioactive (+/-25 microCi/g) low-alloy steels (nuclear reactor surveillance samples) by ion chromatography (IC) is described. The analysis has been done directly without prior separation of the iron matrix. The eluted metal ions have been detected with a UV-visible spectrophotometric detector after post-column complexation with 4-(2-pyridylazo)resorcinol. The results are in a good agreement with the certified values for the standard reference material used. The method was applied to nuclear reactor surveillance samples for the determination of Cu, Mn, Co and Ni. PMID:15048428

  4. Geochemical processes in the Onyx River, Wright Valley, Antarctica: Major ions, nutrients, trace metals

    NASA Astrophysics Data System (ADS)

    Green, William J.; Stage, Brian R.; Preston, Adam; Wagers, Shannon; Shacat, Joseph; Newell, Silvia

    2005-02-01

    We present data on major ions, nutrients and trace metals in an Antarctic stream. The Onyx River is located in Wright Valley (77-32 S; 161-34 E), one of a group of ancient river and glacier-carved landforms that comprise the McMurdo Dry Valleys of Antarctica. The river is more than 30 km long and is the largest of the glacial meltwater streams that characterize this relatively ice-free region near the Ross Sea. The complete absence of rainfall in the region and the usually small contributions of glacially derived tributaries to the main channel make this a comparatively simple system for geochemical investigation. Moreover, the lack of human impacts, past or present, provides an increasingly rare window onto a pristine aquatic system. For all major ions and silica, we observe increasing concentrations with distance from Lake Brownworth down to the recording weir near Lake Vanda. Chemical weathering rates are unexpectedly high and may be related to the rapid dissolution of ancient carbonate deposits and to the severe physical weathering associated with the harsh Antarctic winter. Of the nutrients, nitrate and dissolved reactive phosphate appear to have quite different sources. Nitrate is enriched in waters near the Lower Wright Glacier and may ultimately be derived from stratospheric sources; while phosphate is likely to be the product of chemical weathering of valley rocks and soils. We confirm the work of earlier investigations regarding the importance of the Boulder Pavement as a nutrient sink. Dissolved Mn, Fe, Ni, Cu, and Cd are present at nanomolar levels and, in all cases, the concentrations of these metals are lower than in average world river water. We hypothesize that metal uptake and exchange with particulate phases along the course of the river may serve as a buffer for the dissolved load. Concurrent study of these three solute classes points out significant differences in the mechanisms and sites of their removal from the Onyx River.

  5. Hydrogen transport through oxide metal surface under atom and ion irradiation

    NASA Astrophysics Data System (ADS)

    Begrambekov, L.; Dvoychenkova, O.; Evsin, A.; Kaplevsky, A.; Sadovskiy, Ya; Schitov, N.; Vergasov, S.; Yurkov, D.

    2014-11-01

    Both the latest and earlier achieved results on gas exchange processes on metal surfaces (including stainless steel, titanium, zirconium, tungsten with deposited aluminum oxide coating) under hydrogen atom or plasma irradiation with occasional oxygen impurity are presented in the paper. Mechanisms and regularities of these processes are discussed. It is demonstrated that surface oxide layer properties as a diffusion barrier strongly depend on external influence on the surface. In particular, it is revealed that low energy hydrogen ion irradiation could slow down hydrogen desorption from metals. Hydrogen atom or ion irradiation combined with simultaneous oxygen admixture accelerates hydrogen desorption from metals.

  6. Sub-millimeter Spectroscopy of Astrophysically Important Molecules and Ions: Metal Hydrides, Halides, and Cyanides

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Flory, M. A.; Halfen, D. T.

    2006-01-01

    With the advent of SOFIA, Herschel, and SAFIR, new wavelength regions will become routinely accessible for astronomical spectroscopy, particularly at submm frequencies (0.5-1.1 THz). Molecular emission dominates the spectra of dense interstellar gas at these wavelengths. Because heterodyne detectors are major instruments of these missions, accurate knowledge of transition frequencies is crucial for their success. The Ziurys spectroscopy laboratory has been focusing on the measurement of the pure rotational transitions of astrophysically important molecules in the sub-mm regime. Of particular interest have been metal hydride species and their ions, as well as metal halides and cyanides. A new avenue of study has included metal bearing molecular ions.

  7. Percolation of gallium dominates the electrical resistance of focused ion beam deposited metals

    SciTech Connect

    Faraby, H.; DiBattista, M.; Bandaru, P. R.

    2014-04-28

    Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

  8. Noble metal-comparable SERS enhancement from semiconducting metal oxides by making oxygen vacancies

    PubMed Central

    Cong, Shan; Yuan, Yinyin; Chen, Zhigang; Hou, Junyu; Yang, Mei; Su, Yanli; Zhang, Yongyi; Li, Liang; Li, Qingwen; Geng, Fengxia; Zhao, Zhigang

    2015-01-01

    Surface-enhanced Raman spectroscopy (SERS) represents a very powerful tool for the identification of molecular species, but unfortunately it has been essentially restricted to noble metal supports (Au, Ag and Cu). While the application of semiconductor materials as SERS substrate would enormously widen the range of uses for this technique, the detection sensitivity has been much inferior and the achievable SERS enhancement was rather limited, thereby greatly limiting the practical applications. Here we report the employment of non-stoichiometric tungsten oxide nanostructure, sea urchin-like W18O49 nanowire, as the substrate material, to magnify the substrate–analyte molecule interaction, leading to significant magnifications in Raman spectroscopic signature. The enrichment of surface oxygen vacancy could bring additional enhancements. The detection limit concentration was as low as 10−7 M and the maximum enhancement factor was 3.4 × 105, in the rank of the highest sensitivity, to our best knowledge, among semiconducting materials, even comparable to noble metals without ‘hot spots'. PMID:26183467

  9. Noble metal-comparable SERS enhancement from semiconducting metal oxides by making oxygen vacancies

    NASA Astrophysics Data System (ADS)

    Cong, Shan; Yuan, Yinyin; Chen, Zhigang; Hou, Junyu; Yang, Mei; Su, Yanli; Zhang, Yongyi; Li, Liang; Li, Qingwen; Geng, Fengxia; Zhao, Zhigang

    2015-07-01

    Surface-enhanced Raman spectroscopy (SERS) represents a very powerful tool for the identification of molecular species, but unfortunately it has been essentially restricted to noble metal supports (Au, Ag and Cu). While the application of semiconductor materials as SERS substrate would enormously widen the range of uses for this technique, the detection sensitivity has been much inferior and the achievable SERS enhancement was rather limited, thereby greatly limiting the practical applications. Here we report the employment of non-stoichiometric tungsten oxide nanostructure, sea urchin-like W18O49 nanowire, as the substrate material, to magnify the substrate-analyte molecule interaction, leading to significant magnifications in Raman spectroscopic signature. The enrichment of surface oxygen vacancy could bring additional enhancements. The detection limit concentration was as low as 10-7 M and the maximum enhancement factor was 3.4 × 105, in the rank of the highest sensitivity, to our best knowledge, among semiconducting materials, even comparable to noble metals without `hot spots'.

  10. Colorimetric photonic hydrogel aptasensor for the screening of heavy metal ions.

    PubMed

    Ye, Bao-Fen; Zhao, Yuan-Jin; Cheng, Yao; Li, Ting-Ting; Xie, Zhuo-Ying; Zhao, Xiang-Wei; Gu, Zhong-Ze

    2012-09-28

    We have developed a robust method for the visual detection of heavy metal ions (such as Hg(2+) and Pb(2+)) by using aptamer-functionalized colloidal photonic crystal hydrogel (CPCH) films. The CPCHs were derived from a colloidal crystal array of monodisperse silica nanoparticles, which were polymerized within the polyacrylamide hydrogel. The heavy metal ion-responsive aptamers were then cross-linked in the hydrogel network. During detection, the specific binding of heavy metal ions and cross-linked single-stranded aptamers in the hydrogel network caused the hydrogel to shrink, which was detected as a corresponding blue shift in the Bragg diffraction peak position of the CPCHs. The shift value could be used to estimate, quantitatively, the amount of the target ion. It was demonstrated that our CPCH aptasensor could screen a wide concentration range of heavy metal ions with high selectivity and reversibility. In addition, these aptasensors could be rehydrated from dried gels for storage and aptamer protection. It is anticipated that our technology may also be used in the screening of a broad range of metal ions in food, drugs and the environment. PMID:22936101

  11. Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions.

    PubMed

    Yang, Shengyuan; Wu, Chao; Tan, Hui; Wu, Yan; Liao, Shuzhen; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2013-01-01

    In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors. PMID:23214408

  12. Predicting relative toxicity and interactions of divalent metal ions: Microtox{reg_sign} bioluminescence assay

    SciTech Connect

    Newman, M.C.; McCloskey, J.T.

    1996-03-01

    Both relative toxicity and interactions between paired metal ions were predicted with least-squares linear regression and various ion characteristics. Microtox{reg_sign} 15 min EC50s (expressed as free ion) for Ca(II), Cd(II), Cu(II), Hg(II), Mg(II), Mn(II), Ni(II), Pb(II), and Zn(II) were most effectively modeled with the constant for the first hydrolysis (K{sub H} for M{sup n+} + H{sub 2}O {yields} MOH{sup a{minus}1} + H{sup +}) although other ion characteristics were also significant in regression models. The {vert_bar}log K{sub H}{vert_bar} is correlated with metal ion affinity to intermediate ligands such as many biochemical functional groups with O donor atoms. Further, ordination of metals according to ion characteristics, e.g., {vert_bar}log K{sub H}{vert_bar} facilitated prediction of paired metal interactions. Pairing metals with strong tendencies to complex with intermediate or soft ligands such as those with O or S donor atoms resulted in strong interactions.

  13. XANES Data on Metal Ions in Hydroxyapatite Structures

    NASA Astrophysics Data System (ADS)

    Schaefer, Beth; Tabor-Morris, Anne; Simons, Adrian

    2004-03-01

    The experimental technique of X-ray Absorption Near Edge Structure (XANES) was used to compare the absorption edges of different oxidation states of iron, strontium, lead, copper and zinc in the inorganic mineral structure hydroxyapatite and fluoroapatite. Trace elements such as iron, copper, zinc, lead and strontium are of interest in both biologically and geologically formed apatites. They are thought to occupy substitutional sites at the concentration of about 200 ppm. These metal atoms replace the calcium atom in one of two non-equivalent calcium sites. Hydroxyapatite consists of Ca _5 (OH)(PO_4)3 in a hexagonal crystal structure. Hydroxyapatite formed under geological conditions has the same crystal structure. Data was taken at the X-9B line at the National Synchrotron Light Source at Brookhaven National Laboratory. Samples were obtained from Dr. Susan G. Sheridan, at the University of Notre Dame, Dr. Catherine Skinner from Yale University, Dr. John Rakovan at Miami University in Ohio, Dr. Richard Riman at Rutgers University.

  14. Highly ordered three-dimensional macroporous carbon spheres for determination of heavy metal ions

    SciTech Connect

    Zhang, Yuxiao; Zhang, Jianming; Liu, Yang; Huang, Hui; Kang, Zhenhui

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Highly ordered three dimensional macroporous carbon spheres (MPCSs) were prepared. Black-Right-Pointing-Pointer MPCS was covalently modified by cysteine (MPCS-CO-Cys). Black-Right-Pointing-Pointer MPCS-CO-Cys was first time used in electrochemical detection of heavy metal ions. Black-Right-Pointing-Pointer Heavy metal ions such as Pb{sup 2+} and Cd{sup 2+} can be simultaneously determined. -- Abstract: An effective voltammetric method for detection of trace heavy metal ions using chemically modified highly ordered three dimensional macroporous carbon spheres electrode surfaces is described. The highly ordered three dimensional macroporous carbon spheres were prepared by carbonization of glucose in silica crystal bead template, followed by removal of the template. The highly ordered three dimensional macroporous carbon spheres were covalently modified by cysteine, an amino acid with high affinities towards some heavy metals. The materials were characterized by physical adsorption of nitrogen, scanning electron microscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. High sensitivity was exhibited when this material was used in electrochemical detection (square wave anodic stripping voltammetry) of heavy metal ions due to the porous structure. And the potential application for simultaneous detection of heavy metal ions was also investigated.

  15. Interaction of metal ions with the His13-His14 sequence relevant to Alzheimer's disease.

    PubMed

    Kong, Xiangtao; Zhao, Zhi; Lei, Xin; Zhang, Bingbing; Dai, Dongxu; Jiang, Ling

    2015-04-01

    The interaction of a series of metal ions (i.e., groups 1 and 2, first-row transition metals, and groups 11-14) with the His13-His14 sequence relevant to Alzheimer's disease has been studied using quantum chemical calculations. Metal ions prefer to occupy three coordination sites at two Nδ of the imidazole rings and one carbonyl oxygen. Simulated IR spectra reveal that vibrational frequency of C-O stretch affords a sensitive probe for understanding the interaction of His13-His14 with metal ions. The relative strength of the interaction of His13-His14 with the representative metal ions follows the order of K(+) < Ca(2+) < Zn(2+) < Cu(2+) < Fe(3+) < Al(3+), which is closely correlated with the available experimental results, providing a vivid physical picture about how metal ions bind to amyloid β-peptide. IR spectra of the [M·(His13-His14)](n+) complexes could be measured by infrared photodissociation spectroscopic technique and thus afford useful information for the understanding of structure-function relationship and the design of suitable drugs. PMID:25801452

  16. Ultrahigh-current-density metal-ion implantation and diamondlike-hydrocarbon films for tribological applications

    NASA Astrophysics Data System (ADS)

    Wilbur, P. J.

    1993-09-01

    The metal-ion-implantation system used to implant metals into substrates are described. The metal vapor required for operation is supplied by drawing sufficient electron current from the plasma discharge to an anode-potential crucible so a solid, pure metal placed in the crucible will be heated to the point of vaporization. The ion-producing, plasma discharge is initiated within a graphite-ion-source body, which operates at high temperature, by using an argon flow that is turned off once the metal vapor is present. Extraction of ion beams several cm in diameter at current densities ranging to several hundred micro-A/sq cm on a target 50 cm downstream of the ion source were demonstrated using Mg, Ag, Cr, Cu, Si, Ti, V, B, and Zr. These metals were implanted into over 100 substrates (discs, pins, flats, wires). A model describing thermal stresses induced in materials (e.g. ceramic plates) during high-current-density implantation is presented. Tribological and microstructural characteristics of iron and 304-stainless-steel samples implanted with Ti or B are examined. Diamondlike-hydrocarbon coatings were applied to steel surfaces and found to exhibit good tribological performance.

  17. Transplacental passage of metal ions in women with hip resurfacing: no teratogenic effects observed.

    PubMed

    deSouza, Ruth-Mary; Wallace, David; Costa, Matthew L; Krikler, Stephen J

    2012-01-01

    Over recent years, hip resurfacing has been performed in young, active patients, including women in their child bearing years. Current work investigating the transplacental passage of metal ions (cobalt and chromium) suggests significant passage of ions across the placenta in mothers with metal on metal hip resurfacing. In vitro studies show that cobalt and chromium can create DNA and chromosome damage in human cells. The consequences of this ion transfer on the child during fetal development and thereafter have not been fully quantified. We report on 3 patients with metal on metal hip resurfacings who had the prosthesis in situ during pregnancy. Our data show that umbilical cord blood chromium levels are under a quarter of the maternal serum levels. Cord blood cobalt levels are approximately half that of maternal blood. All 3 children are healthy. Although there was transplacental passage of ions, there was no significant effect on the child in these cases. We did not show any teratogenic effect of metal ions on the child, and this is consistent with the reported literature. PMID:22383325

  18. Alkali-Metal-Ion-Assisted Hydrogen Atom Transfer in the Homocysteine Radical.

    PubMed

    Lesslie, Michael; Lau, Justin Kai-Chi; Lawler, John T; Siu, K W Michael; Oomens, Jos; Berden, Giel; Hopkinson, Alan C; Ryzhov, Victor

    2016-02-12

    Intramolecular hydrogen atom transfer (HAT) was examined in homocysteine (Hcy) thiyl radical/alkali metal ion complexes in the gas phase by combination of experimental techniques (ion-molecule reactions and infrared multiple photon dissociation spectroscopy) and theoretical calculations. The experimental results unequivocally show that metal ion complexation (as opposed to protonation) of the regiospecifically generated Hcy thiyl radical promotes its rapid isomerisation into an α-carbon radical via HAT. Theoretical calculations were employed to calculate the most probable HAT pathway and found that in alkali metal ion complexes the activation barrier is significantly lower, in full agreement with the experimental data. This is, to our knowledge, the first example of a gas-phase thiyl radical thermal rearrangement into an α-carbon species within the same amino acid residue and is consistent with the solution phase behaviour of Hcy radical. PMID:26836574

  19. Structure of apo acyl carrier protein and a proposal to engineer protein crystallization through metal ions

    SciTech Connect

    Qiu, Xiayang; Janson, Cheryl A.

    2010-11-16

    A topic of current interest is engineering surface mutations in order to improve the success rate of protein crystallization. This report explores the possibility of using metal-ion-mediated crystal-packing interactions to facilitate rational design. Escherichia coli apo acyl carrier protein was chosen as a test case because of its high content of negatively charged carboxylates suitable for metal binding with moderate affinity. The protein was successfully crystallized in the presence of zinc ions. The crystal structure was determined to 1.1 {angstrom} resolution with MAD phasing using anomalous signals from the co-crystallized Zn{sup 2+} ions. The case study suggested an integrated strategy for crystallization and structure solution of proteins via engineering surface Asp and Glu mutants, crystallizing them in the presence of metal ions such as Zn{sup 2+} and solving the structures using anomalous signals.

  20. Intercalation of Coordinatively Unsaturated Fe(III) Ion within Interpenetrated Metal-Organic Framework MOF-5.

    PubMed

    Holmberg, Rebecca J; Burns, Thomas; Greer, Samuel M; Kobera, Libor; Stoian, Sebastian A; Korobkov, Ilia; Hill, Stephen; Bryce, David L; Woo, Tom K; Murugesu, Muralee

    2016-06-01

    Coordinatively unsaturated Fe(III) metal sites were successfully incorporated into the iconic MOF-5 framework. This new structure, Fe(III) -iMOF-5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single-crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid-state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe(III) , whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe(III) ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn(II) within the MOF-5 SBU. This new MOF structure displays the potential for metal-site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials. PMID:27061210

  1. Theory of ion-stimulated electron emission from simple metals: Explicit calculations

    SciTech Connect

    Gaspar, J.A. |; Eguiluz, A.G. |; Mills, D.L.

    1995-05-15

    We apply a description of ion-stimulated electron emission from metals developed earlier by one of us [D. L. Mills, Surf. Sci. 294, 161 (1993)] to ions which strike aluminum metal at both grazing and normal incidence. The electronic response of the substrate is modeled within the jellium picture. For grazing incidence, we employ realistic ion trajectories which allow penetration of the ions into the metal. The substrate response is described microscopically, so a proper description of short-wavelength aspects is incorporated fully in our calculations. Response functions employed are those for a jellium slab, so that electron emission mediated by bulk plasmons is described. Our results reproduce very well the experimental data reported by Rau, for the case of grazing incidence. In addition, we present calculations for the case of normal incidence.

  2. Removal of heavy metal ions by biogenic hydroxyapatite: Morphology influence and mechanism study

    NASA Astrophysics Data System (ADS)

    Wang, Dandan; Guan, Xiaomei; Huang, Fangzhi; Li, Shikuo; Shen, Yuhua; Chen, Jun; Long, Haibo

    2016-08-01

    Based on the synthesis of hydroxyapatite (HA) with different morphologies, such as nanorod-like, flower-like and sphere-like assembled HA nanorods, a new strategy has been developed for the removal of heavy metal ions such as Pb2+, Cu2+, Mn2+, Zn2+. The dependence of removal efficiency on the morphology and the suspended concentration of trapping agent, the removal time and selectivity were evaluated and discussed. The experimental results proved that the removal capacity of flower-like assembled HA nanorods (NAFL-HA) was the best, and the maximum removal ratio for Pb2+ ion was 99.97%. The mechanism of Pb2+ removal was studied in detail, noting that some metal ions were completely incorporated into hydroxyapatitie to produce Pb-HA. It reveals that the metal ions capture by HA is mainly controlled by sample surface adsorption and co-precipitation, which are directly controlled by sample morphology.

  3. Determination of equilibrium constants of alkaline earth metal ion chelates with Dowex A-1 chelating resin.

    PubMed

    Harju, L; Krook, T

    1995-03-01

    A complexation chemistry model is applied to chelating ion-exchange systems and a method is presented for the determination of equilibrium constants for metal ion chelates with these resins. Protonation constants for the iminodiacetic based chelating resin Dowex A-1 were determined from potentiometric pH-data. Equilibrium constants were determined for 1:1 beryllium, magnesium, calcium, strontium and barium chelates with the resin in a wide pH range by measuring the concentrations of respective metal ions in the aqueous phase with direct current plasma atomic emission spectrometry (DCP-AES). A batch technique was used for the equilibrium experiments. At pH below 7 protonated 1:1 species were also found to be formed with the resin. From the obtained equilibrium constants, theoretical distribution coefficients were calculated as function of pH for respective metal ion resin system. PMID:18966248

  4. Multiple ionization of metal ions by ECR heating of electrons in vacuum arc plasmas

    NASA Astrophysics Data System (ADS)

    Vodopyanov, A. V.; Golubev, S. V.; Zorin, V. G.; Razin, S. V.; Vizir, A. V.; Nikolaev, A. G.; Oks, E. M.; Yushkov, G. Yu.

    2004-05-01

    A joint research and development effort has been initiated, whose ultimate goal is the enhancement of the mean ion charge states in vacuum arc metal plasmas by a combination of a vacuum arc discharge and electron cyclotron resonance (ECR) heating. Metal plasma was generated by a special vacuum arc mini-gun. Plasma was pumped by high frequency gyrotron-generated microwave radiation. The results have demonstrated substantial multiple ionization of metal ions. For a lead plasma, ECR heating increased the maximum attainable ion charge state from Pb2+ up to Pb6+. The confinement parameter was as high as ˜109 cm-3 s. Further increase of the ion charge states will be attained by increasing the vacuum arc plasma density and optimizing the ECR heating conditions.

  5. Retrieval of metal atom and ion number densities in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Langowski, Martin; Von Savigny, Christian; Burrows, John

    2016-07-01

    When meteoroids enter the Earth's atmosphere with velocities of several 10 km/s, they heat up due to frictional heating and meteoric material is ablated in the upper atmosphere at around 100 km. A certain part of this ablated material are metal atoms and ions, which form layers of about 10 km width at altitudes between 80 to 110 km. The metal atoms and ions are strong emitters of dayglow coming from resonance fluorescence. From satellite observations of these emission signature, densities of the metal atom and ion layers can be retrieved. From the densities of the metal layers in combination with model simulations the input rate of meteoric material can be estimated, which still shows a large uncertainty range between 1 to 300 tons per day. We will present results of the number density retrievals from the SCIAMACHY limb mesosphere and lower thermosphere measurements from 2008 to 2012 for Mg, Mg^{+} and Na.

  6. A nex immobilized hydroxypyridinone as a sequestering agent for heavy metal ions

    NASA Astrophysics Data System (ADS)

    Santos, M. A.; Grazina, R.

    2003-05-01

    New chelating solid matrices were developed for the removal of hard heavy metal ions (ex: Fe^{3+}, Al^{3+}. Pu^{4+}) from water solutions. They are based on the immobilization of 3-hydroxy-4-pyridinone (HP) amino-derivatives by covalent binding to epoxy-activated Sepharose gels, through amine linkages. These HP-functionalized gels are able to strongly chelate those metal ions though formation of 1:1 (metal: HP) complexes. They possess a much higher stability and capacity for sequestering this type of metal ions and in a wider range of pH than the corresponding analogous gels, which involve the CNBr-activated sepharose and have amide/isoureia bonds as the ligand-matrix points of attachment.

  7. Analytical strategies based on quantum dots for heavy metal ions detection

    NASA Astrophysics Data System (ADS)

    Vázquez-González, Margarita; Carrillo-Carrion, Carolina

    2014-10-01

    Heavy metal contamination is one of the major concerns to human health because these substances are toxic and retained by the ecological system. Therefore, in recent years, there has been a pressing need for fast and reliable methods for the analysis of heavy metal ions in environmental and biological samples. Quantum dots (QDs) have facilitated the development of sensitive sensors over the past decade, due to their unique photophysical properties, versatile surface chemistry and ligand binding ability, and the possibility of the encapsulation in different materials or attachment to different functional materials, while retaining their native luminescence property. This paper comments on different sensing strategies with QD for the most toxic heavy metal ions (i.e., cadmium, Cd2+; mercury, Hg and lead, Pb2+). Finally, the challenges and outlook for the QD-based sensors for heavy metals ions are discussed.

  8. A comparative study of metal artifacts from common metal orthodontic brackets in magnetic resonance imaging

    PubMed Central

    Khademi, Jalil; Alizadeh, Ahmad; Babaei Hemmaty, Yasamin; Atrkar Roushan, Zahra

    2015-01-01

    Purpose This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. Materials and Methods A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo T1-weighted images, fast spin-echo T2-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. Results Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. Conclusion With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires. PMID:26389058

  9. The Gellyfish: an in-situ equilibrium-based sampler for determining multiple free metal ion concentrations in marine ecosystems

    EPA Science Inventory

    Free metal ions are usually the most bioavailable and toxic metal species to aquatic organisms, but they are difficult to measure because of their extremely low concentrations in the marine environment. Many of the current methods for determining free metal ions are complicated a...

  10. Method for mobilization of hazardous metal ions in soils

    DOEpatents

    Dugan, Patrick R.; Pfister, Robert M.

    1995-01-01

    A microbial process for removing heavy metals such as bismuth, cadmium, lead, thorium, uranium and other transuranics from soils and sediments, utilizing indigenous, or isolates of indigenous, microorganisms and reducing agents, such as cysteine or sodium thioglycollate, or complexing agents such as the amino acid glycine, to effect the mobilization or release of the metals from the soil particles.

  11. Comparison of synovial fluid, urine, and serum ion levels in metal-on-metal total hip arthroplasty at a minimum follow-up of 18 years.

    PubMed

    Lass, Richard; Grübl, Alexander; Kolb, Alexander; Stelzeneder, David; Pilger, Alexander; Kubista, Bernd; Giurea, Alexander; Windhager, Reinhard

    2014-09-01

    Diagnosis of adverse reactions to metal debris in metal-on-metal hip arthroplasty is a multifactorial process. Systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urine, or synovial fluid levels and adverse local tissue reactions is still incompletely understood. The hypothesis was that elevated serum and urine metal-ion concentrations are associated with elevated local metal-ion concentrations in primary total hip arthroplasties (THA) and with failure of metal-on-metal articulations in the long-term. In our present study, we evaluated these concentrations in 105 cementless THA with metal-on-metal articulating surfaces with small head diameter at a minimum of 18 years postoperatively. Spearman correlation showed a high correlation between the joint fluid aspirate concentration of cobalt and chromium with the serum cobalt (r = 0.81) and chromium level (r = 0.77) in patients with the THA as the only source of metal-ions. In these patients serum metal-ion analysis is a valuable method for screening. In patients with more than one source of metal or renal insufficiency additional investigations, like joint aspirations are an important tool for evaluation of wear and adverse tissue reactions in metal-on-metal THA. PMID:24841922

  12. Two Divalent Metal Ions and Conformational Changes Play Roles in the Hammerhead Ribozyme Cleavage Reaction.

    PubMed

    Mir, Aamir; Chen, Ji; Robinson, Kyle; Lendy, Emma; Goodman, Jaclyn; Neau, David; Golden, Barbara L

    2015-10-20

    The hammerhead ribozyme is a self-cleaving RNA broadly dispersed across all kingdoms of life. Although it was the first of the small, nucleolytic ribozymes discovered, the mechanism by which it catalyzes its reaction remains elusive. The nucleobase of G12 is well positioned to be a general base, but it is unclear if or how this guanine base becomes activated for proton transfer. Metal ions have been implicated in the chemical mechanism, but no interactions between divalent metal ions and the cleavage site have been observed crystallographically. To better understand how this ribozyme functions, we have solved crystal structures of wild-type and G12A mutant ribozymes. We observe a pH-dependent conformational change centered around G12, consistent with this nucleotide becoming deprotonated. Crystallographic and kinetic analysis of the G12A mutant reveals a Zn(2+) specificity switch suggesting a direct interaction between a divalent metal ion and the purine at position 12. The metal ion specificity switch and the pH-rate profile of the G12A mutant suggest that the minor imino tautomer of A12 serves as the general base in the mutant ribozyme. We propose a model in which the hammerhead ribozyme rearranges prior to the cleavage reaction, positioning two divalent metal ions in the process. The first metal ion, positioned near G12, becomes directly coordinated to the O6 keto oxygen, to lower the pKa of the general base and organize the active site. The second metal ion, positioned near G10.1, bridges the N7 of G10.1 and the scissile phosphate and may participate directly in the cleavage reaction. PMID:26398724

  13. Hollow metal target magnetron sputter type radio frequency ion source.

    PubMed

    Yamada, N; Kasuya, T; Tsubouchi, N; Wada, M

    2014-02-01

    A 70 mm diameter 70 mm long compact ion source equipped with a hollow sputtering target has been designed and tested. The hollow sputtering target serves as the radio frequency (RF) plasma excitation electrode at 13.56 MHz. A stable beam of Cu(+) has been extracted when Ar was used as the discharge support gas. In the extracted beam, Cu(+) had occupied more than 85% of the total ion current. Further increase in Cu(+) ions in the beam is anticipated by increasing the RF power and Ar pressure. PMID:24593636

  14. Hollow metal target magnetron sputter type radio frequency ion source

    SciTech Connect

    Yamada, N. Kasuya, T.; Wada, M.; Tsubouchi, N.

    2014-02-15

    A 70 mm diameter 70 mm long compact ion source equipped with a hollow sputtering target has been designed and tested. The hollow sputtering target serves as the radio frequency (RF) plasma excitation electrode at 13.56 MHz. A stable beam of Cu{sup +} has been extracted when Ar was used as the discharge support gas. In the extracted beam, Cu{sup +} had occupied more than 85% of the total ion current. Further increase in Cu{sup +} ions in the beam is anticipated by increasing the RF power and Ar pressure.

  15. Phosphorylated cellulose triacetate-silica composite adsorbent for recovery of heavy metal ion.

    PubMed

    Srivastava, Niharika; Thakur, Amit K; Shahi, Vinod K

    2016-01-20

    Phosphorylated cellulose triacetate (CTA)/silica composite adsorbent was prepared by acid catalyzed sol-gel method using an inorganic precursor (3-aminopropyl triethoxysilane (APTEOS)). Reported composite adsorbent showed comparatively high adsorption capacity for Ni(II) in compare with different heavy metal ions (Cu(2+), Ni(2+), Cd(2+) and Pb(2+)). For Ni(II) adsorption, effect of time, temperature, pH, adsorbent dose and adsorbate concentration were investigated; different kinetic models were also evaluated. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also estimated and equilibrium adsorption obeyed Langmuir and Freundlich isotherms. Developed adsorbent exhibited about 78.8% Ni(II) adsorption at pH: 6 and a suitable candidate for the removal of Ni(II) ions from wastewater. Further, about 65.5% recovery of adsorbed Ni(II) using EDTA solution was demonstrated, which suggested effective recycling of the functionalized beads would enable it to be used in the treatment of contaminated water in industry. PMID:26572476

  16. Recent results from the low inductance Z-discharge metal vapor ion source

    NASA Astrophysics Data System (ADS)

    Debolt, N.; Hershcovitch, A.; Johnson, B. M.; Rostoker, N.; VanDrie, A.; Wessel, F.

    2002-02-01

    The low inductance Z-discharge metal vapor (LIZ-MeV) ion source, which uses a magnetized Z-pinch, is a pseudo-spark device capable of producing intense currents (several kA) of highly charged gold or other ions. Typical operations produce an extracted charge-state distribution with a range in gold ion charge state from 4 to 19. Time-of-flight (TOF) spectra (excluding contributions from impurities) indicate that charge states at least as high as Au+12 were generated. Various TOF spectra are presented here to support this conclusion. Although the results are preliminary, LIZ-MeV shows great potential. Existing heavy-ion sources can produce either high beam currents, but low charge states (e.g., the metal-vapor vacuum arc) or high charge states, but low beam currents (e.g., the electron beam ion source). For ion beam injection our goal has been to develop an ion source that produces both high charge states and high beam currents. The existing LIZ-MeV has sufficiently large electron impact energies and electron current densities, but performance is limited by charge exchange with ambient gas and short confinement times. Plans are underway to add another Z-pinch stage to both lengthen confinement times and to minimize charge-state reducing processes. Such an enhanced LIZ-MeV should eventually produce even larger currents of more highly ionized heavy metal ions for accelerator applications.

  17. Comparative erosion yields, topographical changes and depth profile analysis of ion eroded nickel-based alloys

    NASA Astrophysics Data System (ADS)

    Navinšek, B.; Panjan, P.; Peternel, M.; Žabkar, A.

    1982-03-01

    Polished polycrystalline alloy targets of Inconel 600, Inconel 625 and Nimonic alloy PE 16 were bombarded with 10 keV He + and A + ions at normal incidence and at room temperature. Comparative studies of the ion erosion yield, as measured by step-height measurements, were made. The correlation between the observed topography and the changes in surface composition and depth profile was studied on irradiated samples by AES. Additionally, total sputtering yields were measured on sputtered films of these materials using a quartz crystal microbalance. The results showed that ion erosion yields are different for the three materials studied, while sputtering yields were similar for He + ions and different for A + ions. A non-linear effect was observed for low dose yields when ion dose and fluence dependence was studied. The topography of ion irradiated nickel-based alloys is specific for a chosen metallographic treatment, determining the bulk and surface structure of the target material.

  18. Protein scaffolds for selective enrichment of metal ions

    DOEpatents

    He, Chuan; Zhou, Lu; Bosscher, Michael

    2016-02-09

    Polypeptides comprising high affinity for the uranyl ion are provided. Methods for binding uranyl using such proteins are likewise provided and can be used, for example, in methods for uranium purification or removal.

  19. Craters produced on metals by single ion impacts.

    SciTech Connect

    Birtcher, R. C.

    1998-12-23

    Single ion impacts have been observed using in-situ transmission electron microscopy during irradiation. In addition to internal defects, single-ion impacts create surface craters as large as 12 nm on In, Ag, Pb and Au. Crater formation rates have been determined from video recordings with a time-resolution of 33 milliseconds. The cratering rate for Xe ions increases linearly with increasing target mass density above a threshold density of approximately 7 gm/cm{sup 3}. The cratering rate increases as the ion mass is increased. These results suggest that cratering requires a high energy-density, near-surface displacement cascade. TRIM calculations have been made in an effort to establish a near-surface energy-density criterion for cratering.

  20. Industrial applications of ion implantation into metal surfaces

    SciTech Connect

    Williams, J.M.

    1987-07-01

    The modern materials processing technique, ion implantation, has intriguing and attractive features that stimulate the imaginations of scientists and technologists. Success of the technique for introducing dopants into semiconductors has resulted in a stable and growing infrastructure of capital equipment and skills for use of the technique in the economy. Attention has turned to possible use of ion implantation for modification of nearly all surface related properties of materials - optical, chemical and corrosive, tribological, and several others. This presentation provides an introduction to fundamental aspects of equipment, technique, and materials science of ion implantation. Practical and economic factors pertaining to the technology are discussed. Applications and potential applications are surveyed. There are already available a number of ion-implanted products, including ball-and-roller bearings and races, punches-and-dies, injection screws for plastics molding, etc., of potential interest to the machine tool industry.