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Sample records for acid metal ion

  1. Characterization of metal ion-nucleic acid interactions in solution.

    PubMed

    Pechlaner, Maria; Sigel, Roland K O

    2012-01-01

    Metal ions are inextricably involved with nucleic acids due to their polyanionic nature. In order to understand the structure and function of RNAs and DNAs, one needs to have detailed pictures on the structural, thermodynamic, and kinetic properties of metal ion interactions with these biomacromolecules. In this review we first compile the physicochemical properties of metal ions found and used in combination with nucleic acids in solution. The main part then describes the various methods developed over the past decades to investigate metal ion binding by nucleic acids in solution. This includes for example hydrolytic and radical cleavage experiments, mutational approaches, as well as kinetic isotope effects. In addition, spectroscopic techniques like EPR, lanthanide(III) luminescence, IR and Raman as well as various NMR methods are summarized. Aside from gaining knowledge about the thermodynamic properties on the metal ion-nucleic acid interactions, especially NMR can be used to extract information on the kinetics of ligand exchange rates of the metal ions applied. The final section deals with the influence of anions, buffers, and the solvent permittivity on the binding equilibria between metal ions and nucleic acids. Little is known on some of these aspects, but it is clear that these three factors have a large influence on the interaction between metal ions and nucleic acids.

  2. 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.

  3. 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.

  4. Metal ion-catalyzed nucleic acid alkylation and fragmentation.

    PubMed

    Browne, Kenneth A

    2002-07-10

    Nucleic acid microarrays are a growing technology in which high densities of known sequences are attached to a substrate in known locations (addressed). Hybridization of complementary sequences leads to a detectable signal such as an electrical impulse or fluorescence. This combination of sequence addressing, hybridization, and detection increases the efficiency of a variety of genomic disciplines including those that profile genetic expression, search for single nucleotide polymorphisms (SNPs), or diagnose infectious diseases by sequencing portions of microbial or viral genomes. Incorporation of reporter molecules into nucleic acids is essential for the sensitive detection of minute amounts of nucleic acids on most types of microarrays. Furthermore, polynucleic acid size reduction increases hybridization because of increased diffusion rates and decreased competing secondary structure of the target nucleic acids. Typically, these reactions would be performed as two separate processes. An improvement to past techniques, termed labeling-during-cleavage (LDC), is presented in which DNA or RNA is alkylated with fluorescent tags and fragmented in the same reaction mixture. In model studies with 26 nucleotide-long RNA and DNA oligomers using ultraviolet/visible and fluorescence spectroscopies as well as high-pressure liquid chromatography and mass spectrometry, addition of both alkylating agents (5-(bromomethyl)fluorescein, 5- or 6-iodoacetamidofluorescein) and select metal ions (of 21 tested) to nucleic acids in aqueous solutions was critical for significant increases in both labeling and fragmentation, with >or=100-fold increases in alkylation possible relative to metal ion-free reactions. Lanthanide series metal ions, Pb(2+), and Zn(2+) were the most reactive ions in terms of catalyzing alkylation and fragmentation. While oligonucleotides were particularly susceptible to fragmentation at sites containing phosphorothioate moieties, labeling and cleavage reactions

  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. 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.

  7. Processes controlling metal ion attenuation in acid mine drainage streams

    NASA Astrophysics Data System (ADS)

    Chapman, B. M.; Jones, D. R.; Jung, R. F.

    1983-11-01

    Two acid mine drainage streams have been investigated by detailed analysis of their sediments and waters, to obtain an understanding of the dominant processes which control the transport and attenuation of heavy metals under conditions of chronic high-level pollutant input. One of the water-courses has a thick hydrous iron oxide crust on its bed, where biotically mediated oxidation of ferrous iron resulted in precipitation of amorphous ferric hydroxide, along with substantial quantities of adsorbed silica, sulphate and Al and lesser quantities of As. Small amounts of K and Pb (and possibly hydronium) jarosites were also present in the sediments. Changes in pH and in the concentrations of Cu, Zn, and Cd appear to be mainly the result of dilution by seeps and tributaries. Although no sediment was recovered during collection of water samples from the second stream, saturation index calculations imply that precipitation should have been occurring. The observed down-stream loss of a number of elements supported this conclusion. The solids predicted to be precipitating were A1(OH) 3, Cu 2(OH) 2CO 3, and Fe(OH) 3. Observed decreases in the concentrations of Cd, Zn and Mn can be accounted for on the basis of dilution alone. However, the additional mechanism of neutralization by higher pH inflows is required to account for the decrease in hydrogen ion concentration downstream. The basis for a potentially useful new technique (congruent element analysis) which enables the identification of conservative components in streams is presented. Comparison of logarithmic concentration versus distance plots delineates the point where chemical removal mechanisms become important for each element.

  8. Effect of metal ions on decomposition of chlorinated organic substances by ozonation in acetic acid.

    PubMed

    Okawa, Kiyokazu; Tsai, Tsung-Yueh; Nakano, Yoichi; Nishijima, Wataru; Okada, Mitsumasa

    2005-01-01

    The objective of this study is to find metal ions that enhance the ozone decomposition of chlorinated organic substances in acetic acid. Although the pseudo-first order degradation rate constant for 2,4-DCP by ozone in acetic acid in addition of Ca2+, Mg2+, Al3+ and Fe2+ were almost the same as that with no metal ion, the degradation rate in addition of Mn2+ and Fe3+ were 2.4 and 4.5 times as high as that with no metal ion, respectively. The presence of Fe3+ enhanced the degradation of 2,4-DCP by ozone in acetic acid because Fe3+-phenolate complex which have high reactivity with ozone was produced by the reaction between 2,4-DCP and Fe3+ in acetic acid. PMID:15620744

  9. 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.

  10. Determination of metal ions by high-performance liquid chromatographic separation of their hydroxamic acid chelates

    SciTech Connect

    Palmieri, M.D.; Fritz, J.S.

    1987-09-15

    Metal ions are determined by adding N-methylfurohydroxamic acid to an aqueous sample and then separating the metal chelates by direct injection onto a liquid chromatographic column. Separations on a C/sub 8/ silica column and a polystyrene-divinylbenzene column are compared, with better separations seen on the polymeric column. The complexes formed at low pH values are cationic and are separated by an ion pairing mechanism. Retention times and selectivity of the metal complexes can be varied by changing the pH. Several metal ions can be separated and quantified; separation conditions, linear calibration curve ranges, and detection limits are presented for Zr(IV), Hf(IV), Fe(III), Nb(V), Al(III), and Sb(III). Interferences due to the presence of other ions in solution are investigated. Finally, an antiperspirant sample is analyzed for zirconium by high-performance liquid chromatography.

  11. Protein-gold nanoclusters for identification of amino acids by metal ions modulated ratiometric fluorescence.

    PubMed

    Wang, Min; Mei, Qingsong; Zhang, Kui; Zhang, Zhongping

    2012-04-01

    Here we report that the dual fluorescence emissions from protein-gold (Au) nanoclusters can greatly be modulated by metal ions and the resultant fluorescence ratiometric responses provide a novel sensory method for the identification of amino acids. The protein-gold (Au) nanoclusters were simply synthesized by the reduction of chloroauric acid with bovine serum albumin (BSA), which exhibit dual emissions: the blue at 425 nm from the oxides of BSA, and the red at 635 nm from Au nanoclusters. It has been demonstrated that different metal ions react with BSA-Au nanoclusters and thus greatly affect the two emissions in different ways by fluorescence enhancement or quenching. Interestingly, the addition of amino acids leads to fluorescence ratiometric changes through the interactions with the bound metal ions. When BSA-Au nanocluster probes modulated by four different metal ions were used together to construct a sensor array, different amino acids were clearly discriminated by the distinctive patterns of four ratiometric fluorescence responses. Results and methods reported here provide a unique strategy for the determination of amino acids.

  12. The inhibitory effect of metals and other ions on acid phosphatase activity from Vigna aconitifolia seeds.

    PubMed

    Srivastava, Pramod Kumar; Anand, Asha

    2015-01-01

    Sensitivity of acid phosphatase from Vigna aconitifolia seeds to metal ions, fluoride, and phosphate was examined. All the effectors had different degree of inhibitory effect on the enzyme. Among metal ions, molybdate and ferric ion were observed to be most potent inhibitors and both exhibited mixed type of inhibition. Acid phosphatase activity was inhibited by Cu2+ in a noncompetitive manner. Zn and Mn showed mild inhibition on the enzyme activity. Inhibition kinetics analysis explored molybdate as a potent inhibitor for acid phosphatase in comparison with other effectors used in this study. Fluoride was the next most strong inhibitor for the enzyme activity, and caused a mixed type of inhibition. Phosphate inhibited the enzyme competitively, which demonstrates that inhibition due to phosphate is one of the regulatory factors for enzyme activity.

  13. Phase equilibria and distribution constants of metal ions in diantipyryl alkane-organic acid-hydrochloric acid-water systems

    NASA Astrophysics Data System (ADS)

    Degtev, M. I.; Popova, O. N.; Yuminova, A. A.

    2014-08-01

    The ability of antipyrine and its derivatives (diantipyryl alkanes) to form separating systems in the presence of salicylic (sulfosalicylic) acid and hydrochloric acid and water is studied. The optimum volume of the organic phase, the composition of complexes, and the mechanism for the distribution of metal ions are determined, depending on the concentrations of the main components and the salting-out agent. The complex distribution and extraction constants are calculated.

  14. Interaction of metal ions with acid sites of biosorbents peat moss and Vaucheria and model substances alginic and humic acids

    SciTech Connect

    Crist, R.H.; Martin, J.R.; Crist, D.R.

    1999-07-01

    The interaction between added metal ions and acid sites of two biosorbents, peat moss and the alga Vaucheria, was studied. Results were interpreted in terms of two model substances, alginic acid, a copolymer of guluronic and mannuronic acids present in marine algae, and humic acid in peat moss. For peat moss and Vaucheria at pH 4--6, two protons were displaced per Cd sorbed, after correction for sorbed metals also displaced by the heavy metal. The frequent neglect of exchange of heavy metals for metals either sorbed on the native material or added for pH adjustment leads to erroneous conclusions about proton displacement stoichiometry. Proton displacement constants K{sub ex}{sup H} decreased logarithmically with pH and had similar slopes for alginic acid and biosorbents. This pH effect was interpreted as an electrostatic effect of increasing anionic charge making proton removal less favorable. The maximum number of exchangeable acid sites (capacity C{sub H}) decreased with pH for alginic acid but increased with pH for biosorbents. Consistent with titration behavior, this difference was explained in terms of more weak acid sites in the biosorbents.

  15. Interaction of metal ions and amino acids - Possible mechanisms for the adsorption of amino acids on homoionic smectite clays

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Loew, G. H.; Lawless, J.

    1983-01-01

    A semiempirical molecular orbital method is used to characterize the binding of amino acids to hexahydrated Cu(2+) and Ni(2+), a process presumed to occur when they are adsorbed in the interlamellar space of homoionic smectite clays. Five alpha-amino acids, beta-alanine, and gamma-aminobutyric acid were used to investigate the metal ion and amino acid specificity in binding. It was assumed that the alpha, beta, and gamma-amino acids would bind as bidentate anionic ligands, forming either 1:1 or 1:2 six-coordinated five, six, and seven-membered-ring chelate complexes, respectively. Energies of complex formation, optimized geometries, and electron and spin distribution were determined; and steric constraints of binding of the amino acids to the ion-exchanged cations in the interlamellar spacing of a clay were examined. Results indicate that hexahydrated Cu(2+) forms more stable complexes than hexahydrated Ni(2+) with all the amino acids studied. However, among these amino acids, complex formation does not favor the adsorption of the biological subset. Calculated energetics of complex formation and steric constraints are shown to predict that 1:1 rather than 1:2 metal-amino acid complexes are generally favored in the clay.

  16. Removal of textile dyes and metallic ions using polyelectrolytes and macroelectrolytes containing sulfonic acid groups.

    PubMed

    Caldera Villalobos, M; Peláez Cid, A A; Herrera González, Ana M

    2016-07-15

    This work reports the removal of textile dyes and metallic ions by means of adsorption and coagulation-flocculation using two polyelectrolytes and two macroelectrolytes containing sulfonic acid groups. The adsorption of textile dyes was studied in aqueous solutions containing cationic dyes and in wastewater containing a vat dye. Also, removal of vat and naphthol dyes was studied using the process of coagulation-flocculation. The results show these materials possess elevated adsorption capacity, and they accomplished removal rates above 97% in aqueous solutions. The removal of the vat dye improved the quality of the wastewater notably, and an uncolored effluent was obtained at the end of the treatment. The treatment using adsorption decreased the values for coloration, conductivity, suspended solids, and pH. The removal of vat and naphthol dyes by means of coagulation-flocculation was studied as well, and removal rates of 90% were obtained. The polyelectrolytes and macroelectrolytes also proved effective in the adsorption of metallic ions in wastewater. The treatment using adsorption accomplished high removal rates of metallic ions, and it showed greater selectivity towards Cu(2+), Fe(3+) and Pb(2+). A decrease in the content of solids as well as the values for COD and conductivity was observed in the wastewater as well. The analyses of FT-IR indicated that cationic dyes and metallic ions were chemisorbed by means of ionic exchange.

  17. Removal of textile dyes and metallic ions using polyelectrolytes and macroelectrolytes containing sulfonic acid groups.

    PubMed

    Caldera Villalobos, M; Peláez Cid, A A; Herrera González, Ana M

    2016-07-15

    This work reports the removal of textile dyes and metallic ions by means of adsorption and coagulation-flocculation using two polyelectrolytes and two macroelectrolytes containing sulfonic acid groups. The adsorption of textile dyes was studied in aqueous solutions containing cationic dyes and in wastewater containing a vat dye. Also, removal of vat and naphthol dyes was studied using the process of coagulation-flocculation. The results show these materials possess elevated adsorption capacity, and they accomplished removal rates above 97% in aqueous solutions. The removal of the vat dye improved the quality of the wastewater notably, and an uncolored effluent was obtained at the end of the treatment. The treatment using adsorption decreased the values for coloration, conductivity, suspended solids, and pH. The removal of vat and naphthol dyes by means of coagulation-flocculation was studied as well, and removal rates of 90% were obtained. The polyelectrolytes and macroelectrolytes also proved effective in the adsorption of metallic ions in wastewater. The treatment using adsorption accomplished high removal rates of metallic ions, and it showed greater selectivity towards Cu(2+), Fe(3+) and Pb(2+). A decrease in the content of solids as well as the values for COD and conductivity was observed in the wastewater as well. The analyses of FT-IR indicated that cationic dyes and metallic ions were chemisorbed by means of ionic exchange. PMID:27082258

  18. Effect of various alkaline metal ions on electrochemical behavior of lead electrode in sulfuric acid solution

    NASA Astrophysics Data System (ADS)

    Hirai, Nobumitsu; Yamamoto, Yui

    2015-10-01

    The effect of various alkaline metal ions on electrochemical behavior of lead electrode in sulfuric acid solution has been investigated. It was found that "the specific anodic oxidation peak" appears at the cathodic scan in cyclic voltammogram of lead electrode in sulfuric acid solution containing Li2SO4, K2SO4, Na2SO4, Rb2SO4, or Cs2SO4. The height of the specific anodic oxidation peak varies with the alkaline sulfate in the solution; K2SO4 >> Na2SO4 > Cs2SO4 > Rb2SO4 > Li2SO4. It should be note that alkaline ions exist in lead sulfate formed on lead electrode in sulfuric acid solution containing potassium sulfate when the electrode was immersed in the solution at the rest potential for more than 1 h.

  19. Acrylic acid grafted cellulosic Luffa cylindrical fiber for the removal of dye and metal ions.

    PubMed

    Gupta, Vinod Kumar; Agarwal, Shilpi; Singh, Prerna; Pathania, Deepak

    2013-10-15

    Acrylic acid grafted cellulosic Luffa cylindrical fiber was utilized for the removal of methylene blue and metal ions from the water system using batch process. The grafted sample used was found to demonstrate a maximum grafting efficiency of 90.8% under concentrations of 0.432×10(-3) mol/L, temperature of 35 °C, time of 60 min and pH of 7.0 respectively. The remarkable improvement in thermal properties of the grafted sample was observed. The formation of new bands in FTIR spectra of grafted sample confirmed the grafting of acrylic acid onto the cellulosic fiber. The maximum adsorption capacity of dye onto adsorbent was observed to be 62.15 mg g(-1) at 175 min. A maximum removal of 45.8% was observed for Mg(2+) as compared to other metal ions. High values of correlation coefficient for methylene blue (0.995) and metal ions such as Mg(2+) (0.996), Ni(2+) (0.995), Zn(2+) (0.996) confirmed the applicability of Langmuir isotherm that assumed a monolayer coverage and uniform activity distribution on the adsorbent surface.

  20. 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.

  1. 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

  2. Neutrophil chemotaxis and arachidonic acid metabolism are not linked: evidence from metal ion probe studies

    SciTech Connect

    Turner, S.R.; Turner, R.A.; Smith, D.M.; Johnson, J.A.

    1986-03-05

    Heavy metal ions can inhibit arachidonic acid (AA) metabolism protect against ionophore cytotoxicity (ibid) and inhibit neutrophil chemotaxis. In this study they used Au/sup 3 +/, Zn/sup 2 +/, Cr/sup 3 +/, Mn/sup 2 +/ and Cu/sup 2 +/ as probes of the interrelationships among AA metabolism, ionophore-mediated cytotoxicity, and chemotaxis. Phospholipid deacylation was measured in ionophore-treated cells prelabeled with /sup 3/H-AA. Eicosanoid release from ionophore-treated cells was monitored by radioimmunoassay. Cytoprotection was quantitated as ability to exclude trypan blue. Chemotaxis toward f-met-leu-phe was measured by leading front analysis. The results imply that metal ions attenuate ionophore cytotoxicity by blocking phospholipid deacylation and eicosanoid release. In contrast to previous reports, no correlation between AA metabolism and chemotaxis was demonstrated, suggesting that these 2 processes are not linked.

  3. A mini-review on functional nucleic acids-based heavy metal ion detection.

    PubMed

    Zhan, Shenshan; Wu, Yuangen; Wang, Lumei; Zhan, Xuejia; Zhou, Pei

    2016-12-15

    Recent years have witnessed great progress in developing functional nucleic acids (FNAs)-based sensors for the detection of heavy metal ion. In this review, four types of the FNAs that most widely-used in heavy metal ions detection were briefly introduced and a dozen of recently published review articles which summarized those FNAs-based sensors were introduced. Particularly, according to the degree of automation and system integration, those FNAs-based sensors which belong to the lab-on-a-chip (LOC) category were reviewed in more detail by classifying them into six types such as microfluidic LOC system, microchip, lateral flow dipstick, personal glucose meter, microfluidic paper-based analytical devices (μPADs) and disc-based analytical platform. After gave a brief description of the sensing strategies, properties, advantages or disadvantages of these FNAs-based sensors, existing problems and future perspectives were also discussed. PMID:27395020

  4. A mini-review on functional nucleic acids-based heavy metal ion detection.

    PubMed

    Zhan, Shenshan; Wu, Yuangen; Wang, Lumei; Zhan, Xuejia; Zhou, Pei

    2016-12-15

    Recent years have witnessed great progress in developing functional nucleic acids (FNAs)-based sensors for the detection of heavy metal ion. In this review, four types of the FNAs that most widely-used in heavy metal ions detection were briefly introduced and a dozen of recently published review articles which summarized those FNAs-based sensors were introduced. Particularly, according to the degree of automation and system integration, those FNAs-based sensors which belong to the lab-on-a-chip (LOC) category were reviewed in more detail by classifying them into six types such as microfluidic LOC system, microchip, lateral flow dipstick, personal glucose meter, microfluidic paper-based analytical devices (μPADs) and disc-based analytical platform. After gave a brief description of the sensing strategies, properties, advantages or disadvantages of these FNAs-based sensors, existing problems and future perspectives were also discussed.

  5. Investigation of metal ion extraction and aggregate formation combining acidic and neutral organophosphorous reagents

    SciTech Connect

    Braatz, A.D.; Nilsson, M.; Ellis, R.; Antonio, M.

    2013-07-01

    In the present study, we investigate how varying mixtures of tri-n-butyl phosphate (TBP) and dibutyl phosphate (HDBP) results in enhanced extraction of lanthanum(III), La{sup 3+}, and dysprosium(III), Dy{sup 3+}. Water and metal ion extraction were carefully monitored as a function of TBP:HDBP mole ratio.In addition to these techniques, EXAFS was used to determine the coordination environment of the metal ion in this system. To produce the necessary signal, a concentration of 1.25*10{sup -3} M La{sup 3+} and Dy{sup 3+} was used. Although previous studies of synergistic extraction of metal cations using combinations of neutral and acidic reagents explain the enhanced extraction by increased dehydration of the metal ion and the formation of mixed extractant complexes, our evidence for the increased water extraction coupled with the aggregate formation suggests a reverse micellar aspect to synergism in the system containing TBP and HDBP. It is quite possible that both of these phenomena contribute to our system behavior. The EXAFS data shows that, based on coordination numbers alone, several possible structures may exist. From this study, we cannot provide a definitive answer as to the nature of extraction in this system or the exact complex formed during extraction.

  6. 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.

  7. Proton and metal ion binding to natural organic polyelectrolytes-II. Preliminary investigation with a peat and a humic acid

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.

    1984-01-01

    We summarize here experimental studies of proton and metal ion binding to a peat and a humic acid. Data analysis is based on a unified physico-chemical model for reaction of simple ions with polyelectrolytes employing a modified Henderson-Hasselbalch equation. Peat exhibited an apparent intrinsic acid dissociation constant of 10-4.05, and an apparent intrinsic metal ion binding constant of: 400 for cadmium ion; 600 for zinc ion; 4000 for copper ion; 20000 for lead ion. A humic acid was found to have an apparent intrinsic proton binding constant of 10-2.6. Copper ion binding to this humic acid sample occurred at two types of sites. The first site exhibited reaction characteristics which were independent of solution pH and required the interaction of two ligands on the humic acid matrix to simultaneously complex with each copper ion. The second complex species is assumed to be a simple monodentate copper ion-carboxylate species with a stability constant of 18. ?? 1984.

  8. Transition metal ion-assisted photochemical generation of alkyl halides and hydrocarbons from carboxylic acids

    SciTech Connect

    Carraher, Jack; Pestovsky, Oleg; Bakac, Andreja

    2012-03-14

    Near-UV photolysis of aqueous solutions of propionic acid and aqueous Fe3+ in the absence of oxygen generates a mixture of hydrocarbons (ethane, ethylene and butane), carbon dioxide, and Fe2+. The reaction becomes mildly catalytic (about five turnovers) in the presence of oxygen which converts a portion of alkyl radicals to oxidizing intermediates that reoxidize Fe2+. The photochemistry in the presence of halide ions (X− = Cl−, Br−) generates ethyl halides via halogen atom abstraction from FeXn3−n by ethyl radicals. Near-quantitative yields of C2H5X are obtained at ≥0.05 M X−. Competition experiments with Co(NH3)5Br2+ provided kinetic data for the reaction of ethyl radicals with FeCl2+ (k = (4.0 ± 0.5) × 106 M−1 s−1) and with FeBr2+ (k = (3.0 ± 0.5) × 107 M−1 s−1). Photochemical decarboxylation of propionic acid in the presence of Cu2+ generates ethylene and Cu+. Longer-chain acids also yield alpha olefins as exclusive products. These reactions become catalytic under constant purge with oxygen which plays a dual role. It reoxidizes Cu+ to Cu2+, and removes gaseous olefins to prevent accumulation of Cu+(olefin) complexes and depletion of Cu2+. The results underscore the profound effect that the choice of metal ions, the medium, and reaction conditions exert on the photochemistry of carboxylic acids.

  9. [Development of metal ions analysis by ion chromatography].

    PubMed

    Yu, Hong; Wang, Yuxin

    2007-05-01

    Analysis of metal ions by ion chromatography, including cation-exchange ion chromatography, anion-exchange ion chromatography and chelation ion chromatography, is reviewed. The cation-exchange ion chromatography is a main method for the determination of metal ions. Stationary phases in cation-exchange ion chromatography are strong acid cation exchanger (sulfonic) and weak acid cation exchanger (carboxylic). Alkali metal ions, alkaline earth metal ions, transition metal ions, rare earth metal ions, ammonium ions and amines can be analyzed by cation-exchange ion chromatography with a suitable detector. The anion-exchange ion chromatography is suitable for the separation and analysis of alkaline earth metal ions, transition metal ions and rare earth metal ions. The selectivity for analysis of metal ions with anion-exchange ion chromatography is good. Simultaneous determination of metal ions and inorganic anions can be achieved using anion-exchange ion chromatography. Chelation ion chromatography is suitable for the determination of trace metal ions in complex matrices. A total of 125 references are cited.

  10. Colorimetric sensor array based on gold nanoparticles and amino acids for identification of toxic metal ions in water.

    PubMed

    Sener, Gulsu; Uzun, Lokman; Denizli, Adil

    2014-01-01

    A facile colorimetric sensor array for detection of multiple toxic heavy metal ions (Hg(2+), Cd(2+), Fe(3+), Pb(2+), Al(3+), Cu(2+), and Cr(3+)) in water is demonstrated using 11-mercaptoundecanoic acid (MUA)-capped gold nanoparticles (AuNPs) and five amino acids (lysine, cysteine, histidine, tyrosine, and arginine). The presence of amino acids (which have functional groups that can form complexes with metal ions and MUA) regulates the aggregation of MUA-capped particles; it can either enhance or diminish the particle aggregation. The combinatorial colorimetric response of all channels of the sensor array (i.e., color change in each of AuNP and amino acid couples) enables naked-eye discrimination of all of the metal ions tested in this study with excellent selectivity.

  11. Colorimetric sensor array based on gold nanoparticles and amino acids for identification of toxic metal ions in water.

    PubMed

    Sener, Gulsu; Uzun, Lokman; Denizli, Adil

    2014-01-01

    A facile colorimetric sensor array for detection of multiple toxic heavy metal ions (Hg(2+), Cd(2+), Fe(3+), Pb(2+), Al(3+), Cu(2+), and Cr(3+)) in water is demonstrated using 11-mercaptoundecanoic acid (MUA)-capped gold nanoparticles (AuNPs) and five amino acids (lysine, cysteine, histidine, tyrosine, and arginine). The presence of amino acids (which have functional groups that can form complexes with metal ions and MUA) regulates the aggregation of MUA-capped particles; it can either enhance or diminish the particle aggregation. The combinatorial colorimetric response of all channels of the sensor array (i.e., color change in each of AuNP and amino acid couples) enables naked-eye discrimination of all of the metal ions tested in this study with excellent selectivity. PMID:25330256

  12. Effect of heavy metal ions on neutrophil arachidonic acid metabolism and chemotaxis

    SciTech Connect

    Smith, D.M.; Turner, S.R.; Johnson, J.A.; Turner, R.A.

    1986-05-01

    Heavy metal ions can inhibit arachidonic acid (AA) metabolism, protect against ionophore cytotoxicity (ibid) and inhibit neutrophil chemotaxis. In this study they used Au/sup +3/, Zn/sup +2/, Cr/sup +3/, Mn/sup +2/, and Cu/sup +2/ as probes of the interrelationships among AA metabolism, ionophore-mediated cytotoxicity, and chemotaxis. Phospholipid deacylation was measured in ionophore-treated cells prelabeled with /sup 3/H-AA. Eicosanoid release from ionophore-treated cells was monitored both qualitatively by thin-layer chromatography of /sup 3/H-AA metabolities and quantitatively by radioimmunoassay. Cytoprotection was quantitated as ability to exclude trypan blue. Chemotaxis toward f-Met-Leu-Phe was measured by leading front analysis. The results imply that metal ions attenuate ionophore cytotoxicity by blocking phospholipid deacylation and eicosanoid production. In contrast to previous reports, the data obtained using Au/sup +3/ and Cu/sup +2/ demonstrates no correlation between AA metabolism and chemotaxis, suggesting that these 2 processes are not linked.

  13. Acid-base and metal ion binding properties of 2-thiocytidine in aqueous solution.

    PubMed

    Brasuń, Justyna; Matera, Agnieszka; Sochacka, Elzbieta; Swiatek-Kozlowska, Jolanta; Kozlowski, Henryk; Operschall, Bert P; Sigel, Helmut

    2008-06-01

    The thionucleoside 2-thiocytidine (C2S) occurs in nature in transfer RNAs; it receives attention in diverse fields like drug research and nanotechnology. By potentiometric pH titrations we measured the acidity constants of H(C2S)(+) and the stability constants of the M(C2S)(2+) and M(C2S-H)(+) complexes (M(2+) = Zn(2+), Cd(2+)), and we compared these results with those obtained previously for its parent nucleoside, cytidine (Cyd). Replacement of the (C2)=O unit by (C2)=S facilitates the release of the proton from (N3)H(+) in H(C2S)(+) (pK (a) = 3.44) somewhat, compared with H(Cyd)(+) (pK (a) = 4.24). This moderate effect of about 0.8 pK units contrasts with the strong acidification of about 4 pK units of the (C4)NH(2) group in C2S (pK (a) = 12.65) compared with Cyd (pK (a) approximately 16.7); the reason for this result is that the amino-thione tautomer, which dominates for the neutral C2S molecule, is transformed upon deprotonation into the imino-thioate form with the negative charge largely located on the sulfur. In the M(C2S)(2+) complexes the (C2)S group is the primary binding site rather than N3 as is the case in the M(Cyd)(2+) complexes, though owing to chelate formation N3 is to some extent still involved in metal ion binding. Similarly, in the Zn(C2S-H)(+) and Cd(C2S-H)(+) complexes the main metal ion binding site is the (C2)S(-) unit (formation degree above 99.99% compared with that of N3). However, again a large degree of chelate formation with N3 must be surmised for the M(C2S-H)(+) species in accord with previous solid-state studies of related ligands. Upon metal ion binding, the deprotonation of the (C4)NH(2) group (pK (a) = 12.65) is dramatically acidified (pK (a) approximately 3), confirming the very high stability of the M(C2S-H)(+) complexes. To conclude, the hydrogen-bonding and metal ion complex forming capabilities of C2S differ strongly from those of its parent Cyd; this must have consequences for the properties of those RNAs which contain this

  14. Removal and recovery of metal ions from acid mine drainage using lignite--A low cost sorbent.

    PubMed

    Mohan, Dinesh; Chander, Subhash

    2006-10-11

    Acid mine drainage (AMD), has long been a significant environmental problem resulting from the microbial oxidation of iron pyrite in presence of water and air, affording an acidic solution that contains toxic metal ions. The main objective of this study was to remove and recover metal ions from acid mine drainage (AMD) by using lignite, a low cost sorbent. Lignite has been characterized and used for the AMD treatment. Sorption of ferrous, ferric, manganese, zinc and calcium in multi-component aqueous systems was investigated. Studies were performed at different pH to find optimum pH. To simulate industrial conditions for acid mine wastewater treatment, all the studies were performed using single and multi-columns setup in down flow mode. The empty bed contact time (EBCT) model was used for minimizing the sorbent usage. Recovery of the metal ions as well as regeneration of sorbent was achieved successfully using 0.1 M nitric acid without dismantling the columns. PMID:16784810

  15. New transition metal ion complexes with benzimidazole-5-carboxylic acid hydrazides with antitumor activity.

    PubMed

    Galal, Shadia A; Hegab, Khaled H; Kassab, Ahmed S; Rodriguez, Mireya L; Kerwin, Sean M; el-Khamry, Abdel-Mo'men A; el-Diwani, Hoda I

    2009-04-01

    Metal complexes of 2-methyl-1H-benzimidazole-5-carboxylic acid hydrazide (4a; L(1)) and its Schiff base 2-methyl-N-(propan-2-ylidene)-1H-benzimidazole-5-carbohydrazide (5a; L(2)) with transition metal ions e.g., copper, silver, nickel, iron and manganese were prepared. The complexes formed were 1:1 or 1:2 M:L complexes and have the structural formulae [Cu(L(1))Cl(H(2)O)]Cl x 3 H(2)O (6), [Ag(L(1))NO(3)(H(2)O)] (7), [Ni(L(1))Cl(2)(H(2)O)(2)] x H(2)O (8), [Fe(L(1))Cl(3)(H(2)O)] x 3 H(2)O (9) and [Mn(L(1))(2)Cl(H(2)O)]Cl x 3 H(2)O (10) for ligand L(1), and [Cu(L(2))Cl(2)(H(2)O)(2)] x H(2)O (11), [Ag(L(2))(2)]NO(3) x H(2)O (12), [Ni(L(2))(2)Cl(2)] x 5 H(2)O (13), [Fe(L(2))(2)Cl(2)]Cl x 2 H(2)O (14) and [Mn(L(2))Cl(2)(H(2)O)(2)] x H(2)O (15) for ligand L(2). The antitumor activity of the synthesized compounds has been studied. The silver complex 7 was found to display cytotoxicity (IC(50)=2 microM) against both human lung cancer cell line A549 and human breast cancer cell line MCF-7. PMID:18752870

  16. A new method for the removal of toxic metal ions from acid-sensitive biomaterial

    SciTech Connect

    Seki, Hideshi; Suzuki, Akira

    1997-06-01

    A new method (competitive adsorption method) for the removal of toxic heavy metals from acid-sensitive biomaterials was proposed and it was applied to the removal of cadmium from the midgut gland (MG) of scallop, Patinopecten yessoensis. Insolubilized humic acid, which has been developed in the laboratory, was used as a competitive adsorbent. A metal-complexation model was used to determine the adsorption characteristics of cadmium onto MG. Furthermore, the model was applied to the competitive adsorption system. The results showed that the competitive adsorption method enabled the simultaneous removal of toxic cadmium from both liquid and MG phase under mild acidic condition (pH 5).

  17. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1994-01-25

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 9 figures.

  18. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1996-07-23

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 10 figs.

  19. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1994-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene disphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  20. Phosphonic acid based ion exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1996-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  1. [Effects of thiourea on pH and availability of metal ions in acid red soil].

    PubMed

    Yang, Bo; Wang, Wen; Zeng, Qing-Ru; Zhou, Xi-Hong

    2014-03-01

    Through the simulation research, the effects of application of thiourea and urea on pH and availability of metal ions in acid red soil were studied, and the results showed that after applying urea, the soil pH increased in the first experimental stage and then reduced gradually to a low level, however, decreased trends of soil pH values were inhibited by the application of thiourea, especially when the concentration of thiourea reached to 5.0 mmol x kg(-1) dry soil, the soil pH was stable at high level, which exceeded to 6.0. It proved that the application of thiourea could inhibit the soil acidification due to urea application. After applying urea with different concentrations of thiourea, the available contents of Zn and Al decreased with the increasing concentration of thiourea, nevertheless, when the concentration of thiourea reached to 5.0 mmol x kg(-1), the available content of Mn was stable at high level which was over 110 mg x kg(-1). In addition, the results showed a highly significant negative correlation between the soil pH and the available content of Cu, Zn and Al, but for Mn, no discipline was found between the soil pH and the availability after applying thiourea. Moreover, the soil pH became higher after applying urea with thiourea compared to add urea only, which led to the decreasing of available content of Al, and it was benefited for the control of the phytotoxic effect of Al. The available content of Mn in the soil not only depended on soil pH but also the content of thiourea due to its redox and complexing reaction with Mn.

  2. A multinuclear NMR relaxation study of the interaction of divalent metal ions with L-aspartic acid.

    PubMed

    Khazaeli, S; Viola, R E

    1984-09-01

    Carbon-13 spin-lattice relaxation times, T1, have been measured for aqueous solutions of L-aspartic acid, L-alanine, O-phospho-L-serine, and 2-mercapto-L-succinic acid in the presence of the paramagnetic metal ions, Cu2+ and Mn2+, and Mg2+ as a diamagnetic control, at ambient temperature and neutral pH. Nitrogen-15, oxygen-17 and proton relaxation times were also obtained for L-aspartic acid and phosphorus-31 relaxation times for O-phospho-L-serine under similar conditions. The structures of these complexes in solution were determined from the various metal ion-nuclei distances calculated from the paramagnetically-induced relaxation. These results indicate that the Cu2+ interaction with L-aspartic acid is through alpha-amino and beta-carboxyl groups while Mn2+ coordinates most strongly through alpha- and beta-carboxyl groups, with the possibility of a weak interaction through the amino group. An examination of the coordination of these divalent metal ions to an analog of L-aspartic acid in which the beta-carboxyl group is replaced by a phosphate group (O-phospho-L-serine) indicated that Cu2+ coordination is now probably through the alpha-amino and phosphate groups, while this analog is a monodentate ligand for Mn2+ coordinating through the phosphate group. Removal of the beta-carboxyl group (L-alanine) also results in Cu2+ coordination through the alpha-carboxyl and alpha-amino groups, and the same ligand interactions are observed with Mn2+. Replacement of the alpha-amino group of L-aspartic acid with an -SH group (2-mercapto-L-succinate) is sufficient to eliminate any specific coordination with either Cu2+ or Mn2+. PMID:6491655

  3. New Insight into Metal Ion-Driven Catalysis of Nucleic Acids by Influenza PA-Nter.

    PubMed

    Kotlarek, Daria; Worch, Remigiusz

    2016-01-01

    PA subunit of influenza RNA-dependent RNA polymerase deserves constantly increasing attention due to its essential role in influenza life cycle. N-terminal domain of PA (PA-Nter) harbors endonuclease activity, which is indispensable in viral transcription and replication. Interestingly, existing literature reports on in vitro ion preferences of the enzyme are contradictory. Some show PA-Nter activity exclusively with Mn2+, whereas others report Mg2+ as a natural cofactor. To clarify it, we performed a series of experiments with varied ion concentrations and substrate type. We observed cleavage in the presence of both ions, with a slight preference for manganese, however PA-Nter activity highly depended on the amount of residual, co-purified ions. Furthermore, to quantify cleavage reaction rate, we applied fluorescence cross-correlation spectroscopy (FCCS), providing highly sensitive and real-time monitoring of single molecules. Using nanomolar ssDNA in the regime of enzyme excess, we estimated the maximum reaction rate at 0.81± 0.38 and 1.38± 0.34 nM/min for Mg2+ and Mn2+, respectively. However, our calculations of PA-Nter ion occupancy, based on thermodynamic data, suggest Mg2+ to be a canonical metal in PA-Nter processing of RNA in vivo. Presented studies constitute a step toward better understanding of PA-Nter ion-dependent activity, which will possibly contribute to new successful inhibitor design in the future.

  4. New Insight into Metal Ion-Driven Catalysis of Nucleic Acids by Influenza PA-Nter

    PubMed Central

    Kotlarek, Daria; Worch, Remigiusz

    2016-01-01

    PA subunit of influenza RNA-dependent RNA polymerase deserves constantly increasing attention due to its essential role in influenza life cycle. N-terminal domain of PA (PA-Nter) harbors endonuclease activity, which is indispensable in viral transcription and replication. Interestingly, existing literature reports on in vitro ion preferences of the enzyme are contradictory. Some show PA-Nter activity exclusively with Mn2+, whereas others report Mg2+ as a natural cofactor. To clarify it, we performed a series of experiments with varied ion concentrations and substrate type. We observed cleavage in the presence of both ions, with a slight preference for manganese, however PA-Nter activity highly depended on the amount of residual, co-purified ions. Furthermore, to quantify cleavage reaction rate, we applied fluorescence cross-correlation spectroscopy (FCCS), providing highly sensitive and real-time monitoring of single molecules. Using nanomolar ssDNA in the regime of enzyme excess, we estimated the maximum reaction rate at 0.81± 0.38 and 1.38± 0.34 nM/min for Mg2+ and Mn2+, respectively. However, our calculations of PA-Nter ion occupancy, based on thermodynamic data, suggest Mg2+ to be a canonical metal in PA-Nter processing of RNA in vivo. Presented studies constitute a step toward better understanding of PA-Nter ion-dependent activity, which will possibly contribute to new successful inhibitor design in the future. PMID:27300442

  5. 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)

  6. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity.

    PubMed

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-01-01

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment. PMID:26593782

  7. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity

    PubMed Central

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-01-01

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment. PMID:26593782

  8. Hydrometallurgical process for the recovery of metal values from spent lithium-ion batteries in citric acid media.

    PubMed

    Chen, Xiangping; Zhou, Tao

    2014-11-01

    In this paper, a hydrometallurgical process has been proposed to recover valuable metals from spent lithium-ion batteries in citric acid media. Leaching efficiencies as high as 97%, 95%, 94%, and 99% of Ni, Co, Mn, and Li were achieved under the optimal leaching experimental conditions of citric acid concentration of 2 mol L(-1), leaching temperature of 80 °C, leaching time of 90 min, liquid-solid ratio of 30 ml g(-1), and 2 vol. % H2O2. For the metals recovery process, nickel and cobalt were selectively precipitated by dimethylglyoxime reagent and ammonium oxalate sequentially. Then manganese was extracted by Na-D2EHPA and the manganese-loaded D2EHPA was stripped with sulfuric acid. The manganese was recovered as MnSO4 in aqueous phase and D2EHPA could be reused after saponification. Finally, lithium was precipitated by 0.5 mol L(-1) sodium phosphate. Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively. This is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media.

  9. Hydrometallurgical process for the recovery of metal values from spent lithium-ion batteries in citric acid media.

    PubMed

    Chen, Xiangping; Zhou, Tao

    2014-11-01

    In this paper, a hydrometallurgical process has been proposed to recover valuable metals from spent lithium-ion batteries in citric acid media. Leaching efficiencies as high as 97%, 95%, 94%, and 99% of Ni, Co, Mn, and Li were achieved under the optimal leaching experimental conditions of citric acid concentration of 2 mol L(-1), leaching temperature of 80 °C, leaching time of 90 min, liquid-solid ratio of 30 ml g(-1), and 2 vol. % H2O2. For the metals recovery process, nickel and cobalt were selectively precipitated by dimethylglyoxime reagent and ammonium oxalate sequentially. Then manganese was extracted by Na-D2EHPA and the manganese-loaded D2EHPA was stripped with sulfuric acid. The manganese was recovered as MnSO4 in aqueous phase and D2EHPA could be reused after saponification. Finally, lithium was precipitated by 0.5 mol L(-1) sodium phosphate. Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively. This is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media. PMID:25378255

  10. Tunicate-Inspired Gallic Acid/Metal Ion Complex for Instant and Efficient Treatment of Dentin Hypersensitivity.

    PubMed

    Prajatelistia, Ekavianty; Ju, Sung-Won; Sanandiya, Naresh D; Jun, Sang Ho; Ahn, Jin-Soo; Hwang, Dong Soo

    2016-04-20

    Dentin hypersensitivity is sharp and unpleasant pains caused by exposed dentinal tubules when enamel outside of the tooth wears away. The occlusion of dentinal tubules via in situ remineralization of hydroxyapatite is the best method to alleviate the symptoms caused by dentin hypersensitivity. Commercially available dental desensitizers are generally effective only on a specific area and are relatively toxic, and their performance usually depends on the skill of the clinician. Here, a facile and efficient dentin hypersensitivity treatment with remarkable aesthetic improvement inspired by the tunicate-self-healing process is reported. As pyrogallol groups in tunicate proteins conjugate with metal ions to heal the torn body armor of a tunicate, the ingenious mechanism by introducing gallic acid (GA) as a cheap, abundant, and edible alternative to the pyrogallol groups of the tunicate combined with a varied daily intake of metal ion sources is mimicked. In particular, the GA/Fe(3+) complex exhibits the most promising results, to the instant ≈52% blockage in tubules within 4 min and ≈87% after 7 d of immersion in artificial saliva. Overall, the GA/metal ion complex-mediated coating is facile, instant, and effective, and is suggested as an aesthetic solution for treating dentin hypersensitivity. PMID:26867019

  11. Introduction of multiphosphonate ligand to peptide nucleic acid for metal ion conjugation

    PubMed Central

    Aiba, Yuichiro; Honda, Yuta; Han, Yue; Komiyama, Makoto

    2012-01-01

    Peptide nucleic acid (PNA) is one of the most widely used synthetic DNA analogs. Conjugation of functional molecules to PNA is very effective to further widen its potential applications. For this purpose, here we report the synthesis of several ligand monomers and introduced them to PNA. These ligand-modified PNAs attract cerium ion and are useful for site-selective DNA hydrolysis. It should be noted that these ligands on PNA are also effective even under the conditions of invasion complex. PMID:22772037

  12. Enhanced capacity of chitosan for transition-metal ions in sulphate-sulphuric acid solutions.

    PubMed

    Muzzarelli, R A; Rocchetti, R

    1974-11-01

    Batch measurements have shown that the collection yields of chitosan for chromium(III), iron(III), nickel, copper(II), zinc and mercury(II) from sulphuric acid solutions are higher when the solutions contain ammonium sulphate, or when chitosan conditioned in ammonium sulphate is used, particularly at pH 3.0 and 5.0. The contrary is verified for the oxy-anions vanadate, chromate and molybdate. Manganese is never collected. At pH 1.0 no collection occurs. A procedure for recycling chromatographic columns includes fixation of Cu or Ni from a sulphate solution at pH 3-5 on sulphate-conditioned chitosan, and elution with 0.1M sulphuric acid/0.1M ammonium sulphate at pH 1.0; the presence of sulphate in the eluent obviates the detrimental effect of sulphuric acid on the next cycle. Sulphate is the favoured counter-ion of the chelated cations and its action produces shorter chromatographic bands. The interaction of sulphate with chitosan is discussed in terms of crystallinity and steric distribution of the protonated amino-groups in the polymer. Data on the new diethylaminohydroxypropylcellulose are included. PMID:18961577

  13. Separation of selected transition metals by capillary chelation ion chromatography using acetyl-iminodiacetic acid modified capillary polymer monoliths.

    PubMed

    Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

    2012-08-01

    Capillary housed laurylmethacrylate-co-ethylene dimethacrylate (LMA-co-EDMA) polymer monoliths were fabricated, functionalised with varying amounts of vinyl azlactone, followed by immobilisation of iminodiacetic acid (IDA), forming a range of acetyl-iminodiacetic acid (AIDA) functionalised monoliths, applied to the chelation ion chromatographic separation of selected transition and heavy metals. A number of monoliths of varying length and ligand density were prepared, resulting in increased cation retention and chromatographic resolution on those displaying the highest capacity. Ligand density and related column capacity were confirmed visually using scanning capacitively coupled contactless conductivity detection (sC(4)D) techniques. Column temperature studies to determine retention mechanism and the effect of temperature on the retention of Mn(II), Cd(II) and Cu(II) was investigated, showing an increase in retention with increased temperature for Cd(II) and Cu(II), whilst a decrease in retention was obtained for Mn(II). Isocratic capillary chelation ion chromatographic separations of Mn(II), Cd(II) and Cu(II) were obtained, with dual peak detection demonstrated using combined on-column C(4)D detection and UV-Visible detection following the post-capillary column reaction of the eluted metals with 4-(2-pyridylazo) resorcinol (PAR).

  14. Measuring distances between TRPV1 and the plasma membrane using a noncanonical amino acid and transition metal ion FRET

    PubMed Central

    Gordon, Moshe T.; Senning, Eric N.; Munari, Mika A.

    2016-01-01

    Despite recent advances, the structure and dynamics of membrane proteins in cell membranes remain elusive. We implemented transition metal ion fluorescence resonance energy transfer (tmFRET) to measure distances between sites on the N-terminal ankyrin repeat domains (ARDs) of the pain-transducing ion channel TRPV1 and the intracellular surface of the plasma membrane. To preserve the native context, we used unroofed cells, and to specifically label sites in TRPV1, we incorporated a fluorescent, noncanonical amino acid, L-ANAP. A metal chelating lipid was used to decorate the plasma membrane with high-density/high-affinity metal-binding sites. The fluorescence resonance energy transfer (FRET) efficiencies between L-ANAP in TRPV1 and Co2+ bound to the plasma membrane were consistent with the arrangement of the ARDs in recent cryoelectron microscopy structures of TRPV1. No change in tmFRET was observed with the TRPV1 agonist capsaicin. These results demonstrate the power of tmFRET for measuring structure and rearrangements of membrane proteins relative to the cell membrane. PMID:26755770

  15. Measuring distances between TRPV1 and the plasma membrane using a noncanonical amino acid and transition metal ion FRET.

    PubMed

    Zagotta, William N; Gordon, Moshe T; Senning, Eric N; Munari, Mika A; Gordon, Sharona E

    2016-02-01

    Despite recent advances, the structure and dynamics of membrane proteins in cell membranes remain elusive. We implemented transition metal ion fluorescence resonance energy transfer (tmFRET) to measure distances between sites on the N-terminal ankyrin repeat domains (ARDs) of the pain-transducing ion channel TRPV1 and the intracellular surface of the plasma membrane. To preserve the native context, we used unroofed cells, and to specifically label sites in TRPV1, we incorporated a fluorescent, noncanonical amino acid, L-ANAP. A metal chelating lipid was used to decorate the plasma membrane with high-density/high-affinity metal-binding sites. The fluorescence resonance energy transfer (FRET) efficiencies between L-ANAP in TRPV1 and Co(2+) bound to the plasma membrane were consistent with the arrangement of the ARDs in recent cryoelectron microscopy structures of TRPV1. No change in tmFRET was observed with the TRPV1 agonist capsaicin. These results demonstrate the power of tmFRET for measuring structure and rearrangements of membrane proteins relative to the cell membrane.

  16. Interactions of Phenolic Acids, Metallic Ions and Chelating Agents on Auxin-Induced Growth

    PubMed Central

    Tomaszewski, Miroslaw; Thimann, Kenneth V.

    1966-01-01

    By growth experiments in indoleacetic acid-1-14C (IAA), and determination of the 14CO2 evolved, it has been shown directly that polyphenols synergize IAA-induced growth by counteracting IAA decarboxylation. Sinapic and ferulic acids act like polyphenols. Endogenous polyphenols doubtless exert the same influence in intact plants. Monophenols stimulate the decarboxylation of IAA under conditions where they depress growth. When Mn++ is present as well, this effect is enhanced. All these growth effects are paralleled by effects on the isolated IAA oxidizing enzyme of Avena. EDTA acts like the polyphenols in depressing the decarboxylation of IAA, and not synergizing with the growth induced by naphthalene-acetic acid (NAA) and 2,4-D. However, since EDTA synergizes with IAA for growth even at optimal IAA concentrations, its growth promotion probably involves an additional effect. DIECA inhibits powerfully the destruction of IAA, but without causing much growth promotion, apparently because its decomposition products inhibit respiration. Mn++ aloné stimulates the decarboxylation of IAA, i.e. this ion promotes the IAA oxidase in vivo as it does in vitro. Nevertheless, it does not inhibit elongation, but at relatively high concentrations even stimulates it, both at low and high IAA levels. Since Mn++ also promotes the growth induced by NAA and 2,4-D, its growth action cannot rest primarily on modifying the metabolism of the auxins. Cobalt somewhat decreases the decarboxylation of IAA, but this cannot explain its growth promotion, since Co++, like Mn++, stimulates elongation even at optimal IAA concentrations, and acts with NAA just as well as with IAA. Ferrous ion, on the other hand, acts like the polyphenols. Floating pea stem sections exude enough organic matter to support bacteria which after 7 hours cause considerable decarboxylation of IAA. Avena coleoptile sections have a comparable though smaller effect after 12 hours. The present experiments, with those of others

  17. Two-photon probes for intracellular free metal ions, acidic vesicles, and lipid rafts in live tissues.

    PubMed

    Kim, Hwan Myung; Cho, Bong Rae

    2009-07-21

    Optical imaging with fluorescence microscopy is a vital tool in the study of living systems. The most common method for cell imaging, one-photon microscopy (OPM), uses a single photon of higher energy to excite the fluorophore. However, two-photon microscopy (TPM), which uses two photons of lower energy as the excitation source, is growing in popularity among biologists because of several distinct advantages. Using TPM, researchers can image intact tissue for a long period of time with minimum interference from tissue preparation artifacts, self-absorption, autofluorescence, photobleaching, and photodamage. However, to make TPM a more versatile tool in biology, researchers need a wider variety of two-photon probes for specific applications. In this Account, we describe a series of two-photon probes that we developed that can visualize the distribution of intracellular metal ions, acidic vesicles, and lipid rafts in living cells and tissues. The development of these probes requires a significant two-photon cross section for the bright image and receptors (sensing moieties) that triggers the emission of the two-photon excited fluorescence upon binding with the ions or membrane in the living system. These probes also must be sensitive to the polarity of the environment to allow selective detection of cytosolic and membrane-bound probes. In addition, they need to be cell-permeable, water-soluble for the staining of cells and tissues, and highly photostable for long-term imaging. The resulting probes-AMg1 (Mg(2+)), ACa1-ACa3 (Ca(2+)), AZn1 and AZn2 (Zn(2+)), AH1, AH2, and AL1 (acidic vesicles), and CL2 (membrane)-use 2-acetyl-6-aminonaphthalene as the fluorophore and receptors for the target ions or membrane. All of these two-photon turn-on probes can detect the intracellular free metal ions, acidic vesicles, and lipid rafts at 100-300 microm depth in live tissues. Moreover, with ACa1-AM, we could simultaneously visualize the spontaneous Ca(2+) waves in the somas of

  18. Thermodynamic Features of Benzene-1,2-Diphosphonic Acid Complexes with Several Metal Ions

    SciTech Connect

    Syouhei Nishihama; Ryan P. Witty; Leigh R Martin; Kenneth L. Nash

    2013-08-01

    Among his many contributions to the advancement of f-element chemistry and separation science, Professor Gregory R. Choppin’s research group completed numerous investigations featuring the application of distribution techniques to the determination of metal complexation equilibrium quotients. Most of these studies focused on the chemistry of lanthanide and actinide complexes. In keeping with that tradition, this report discusses the complex formation equilibrium constants for complexes of trivalent europium (Eu3+) with benzene-1,2-diphosphonic acid (H4BzDP) determined using solvent extraction distribution experiments in 0.2 M (Na,H)ClO4 media in the temperature range of 5 – 45 degrees C. Protonation constants for HnBzDP4-n and stoichiometry and stability of BzDP4- complexes with Zn2+, Ni2+, and Cu2+ have also been determined using potentiometric titration (at I = 0.1 M) and 31P NMR spectroscopy. Heats of protonation of HnBzDPn-4 species have been determined by titration calorimetry. From the temperature dependence of the complex Eu3+-HnBzDPn-4 equilibrium constant, a composite enthalpy (?H = -15.1 (+/-1.0) kJ mol-1) of complexation has been computed. Comparing these thermodynamic parameters with literature reports on other diphosphonic acids and structurally similar carboxylic acids indicates that exothermic heats of complexation are unique to the Eu-BzDP system. Comparisons with thermodynamic data from the literature indicate that the fixed geometry imposed by the benzene ring enhances complex stability.

  19. Preparation and Characterization of Bi-metallic and Tri-metallic Metal Organic Frameworks Based on Trimesic Acid and Co(II), Ni(II), and Cu(II) Ions

    NASA Astrophysics Data System (ADS)

    Sahiner, Nurettin; Demirci, Sahin; Yildiz, Mustafa

    2016-10-01

    Trimesic acid-M1(II):M2(II) (M1,2(II)=M(II)=Co(II), Ni(II) and Cu(II)) bi-metallic or tri-metallic organic frameworks (MOFs) were synthesized by the reaction of trimesic acid (H3BTC) ligand with the corresponding MCl2nH2O aqueous solutions. Here, bi- and tri-metallic MOF preparations were demonstrated by using H3BTC as an organic linker, with dual metal ion mixtures at different mole ratios such as Co(II):Ni(II), Ni(II):Cu(II), and Cu(II):Co(II) as metal ion sources in the synthesis of bi-metallic MOFs, and the triple metal ion mixture of Co(II):Ni(II):Cu(II) as the metal ion source in the synthesis of tri-metallic MOFs. The bi- or tri-metallic MOFs were characterized via the Brunauer-Emmett-Teller method, thermogravimetric analyzer (TGA), and magnetic susceptibility measurements with the Gouy method, FT-IR spectroscopy, and electronic spectral studies. The results revealed that the H3BTC MOFs have octahedral and distorted octahedral arrangement around the metal ions, and the d-d transition was not observed in the complex. It was further found that all the prepared MOFs contain water molecules confirmed by Fourier transform infrared (FT-IR) and TGA analyses. The FT-IR spectra of the MOF complexes were characterized by the appearance of a broad band in the region of 3454-3300 cm-1 due to the ν(-OH) of the coordinated water; therefore, the location of the two water molecules was assumed to be inside the complex structure. Remarkably, the synthesized bi-metallic MOFs had unique and distinct colors depending on the amounts of metal ions used in the feed, implying that these bi-metallic MOFs with tunable M1(II) and M2(II) ratios offer great potential in the design of color-coded materials for use as sensors.

  20. Probing metal ion complexation with salicylic acid and its derivatives with excited state proton transfer and luminescence anisotropy

    SciTech Connect

    Wang, Z.; Friedrich, D.M.; Ainsworth, C.C.

    1996-10-01

    Salicylic acid and its derivatives in which the phenolic proton is preserved show a characteristic dual fluorescence: one band in the UV, due to a {open_quotes}normal{close_quotes} excited state emission, and the other in the visible range, is assigned to excited state intramolecular proton transfer (ESIPT). The transition energy, quantum yield and fluorescence lifetime as well as fluorescence anisotropy are sensitive to the solvent environment, temperature and properties of the substituents (complexation) at the phenolic and carboxylic oxygens. The ESIPT band disappears in molecules in which the intramolecular hydrogen bond between phenolic hydrogen and the carbonyl oxygen is prohibited. In this work, the complexation of Na(I), Ca(II), Al(III) and La(III) with salicylic acid, 3-hydroxybenzoic acid, methylsalicylate and anisic acid in both aqueous and non-aqueous solvents has been studied by absorption and steady state luminescence spectroscopy, picosecond to nanosecond luminescence lifetimes and luminescence anisotropy measurements in a range of solvent and in ethanol at 77 K. Speciation in these complex systems, binding characteristics between the metal ion and the ligand, and ligand-centered energetics are discussed in terms of the spectroscopic properties, luminescence and anisotropy decay kinetics.

  1. Immobilized chiral tropine ionic liquid on silica gel as adsorbent for separation of metal ions and racemic amino acids.

    PubMed

    Qian, Guofei; Song, Hang; Yao, Shun

    2016-01-15

    Tropine-type chiral ionic liquid with proline anion was immobilized on silica gel by chemical modification method for the first time, which was proved by elemental, infrared spectrum and thermogravimetric analysis. Secondly, the performance of this kind of ionic liquid-modified silica gel was investigated in the adsorption of some metal ions, which included Cu(2+), Fe(3+), Mn(2+) and Ni(2+). Then the effects of time, initial concentration and temperature on adsorption for Cu(2+) ions were studied in detail, which was followed by the further research of adsorption kinetics and thermodynamics. The adsorption could be better described by pseudo-second-order kinetics model and that the process was spontaneous, exothermic and entropy decreasing. In the mode of 'reuse after adsorption', the ionic liquid-modified silica gel with saturated adsorption of Cu(2+) was finally used in resolution of racemic amino acids for the first time. The static experiment showed that adsorption rate of two enantiomers was obviously different. Inspired by this, the complex was packed in chromatographic column for the separation of racemic amino acids and d-enantiomers were firstly eluted by water or ethanol. Steric hindrance was found as one of key influencing factors for its effect on the stability of the complex.

  2. Immobilized chiral tropine ionic liquid on silica gel as adsorbent for separation of metal ions and racemic amino acids.

    PubMed

    Qian, Guofei; Song, Hang; Yao, Shun

    2016-01-15

    Tropine-type chiral ionic liquid with proline anion was immobilized on silica gel by chemical modification method for the first time, which was proved by elemental, infrared spectrum and thermogravimetric analysis. Secondly, the performance of this kind of ionic liquid-modified silica gel was investigated in the adsorption of some metal ions, which included Cu(2+), Fe(3+), Mn(2+) and Ni(2+). Then the effects of time, initial concentration and temperature on adsorption for Cu(2+) ions were studied in detail, which was followed by the further research of adsorption kinetics and thermodynamics. The adsorption could be better described by pseudo-second-order kinetics model and that the process was spontaneous, exothermic and entropy decreasing. In the mode of 'reuse after adsorption', the ionic liquid-modified silica gel with saturated adsorption of Cu(2+) was finally used in resolution of racemic amino acids for the first time. The static experiment showed that adsorption rate of two enantiomers was obviously different. Inspired by this, the complex was packed in chromatographic column for the separation of racemic amino acids and d-enantiomers were firstly eluted by water or ethanol. Steric hindrance was found as one of key influencing factors for its effect on the stability of the complex. PMID:26711153

  3. 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.

  4. The effect of sugar, amino acid, metal ion, and NaCl on model Maillard reaction under pH control.

    PubMed

    Kwak, E-J; Lim, S-I

    2004-08-01

    The color intensities was determined of Maillard reaction products (MRPs) prepared by heating each of five sugars (maltose, fructose, glucose, arabinose, and xylose) with each of 12 amino acids (aspartic acid, glutamic acid, alanine, leucine, isoleucine, valine, proline, serine, cysteine, phenylalanine, arginine, and lysine). The remaining percentages of glucose and rate of change of color intensity due to the addition of a metal ion and NaCl were monitored for nine MRPs that had been formed between glucose and each of nine amino acids (aspartic acid, glutamic acid, alanine, valine, serine, cysteine, phenylalanine, arginine, and lysine). Model MRPs were prepared in a block heater at 100 degrees C for 1-12 h with the pH value controlled at 6.5. The resulting color intensity of each MRPs formed from the basic amino acids was greater due to the higher reactivity than those from the acidic amino acids. The remaining percentage of glucose in each MRPs from the basic amino acids was lower than those from the acidic amino acids. The MRPs from the nonpolar amino acids showed an intermediate color intensity and remaining percentages of glucose between those formed from the basic and acidic amino acids. Browning tended to be accelerated in the presence of metal ions, especially Fe2+ and Cu2+, although it was affected by the property of the amino acid and heating time as well as by the type of metal ion. On the other hand, browning was greatly inhibited by a high concentration of NaCl.

  5. Synthesis, structural characterization and biological studies of some nalidixic acid-metal complexes: Metalloantibiotic complexes of some divalent and trivalent metal ions

    NASA Astrophysics Data System (ADS)

    Al-Khodir, Fatima A. I.; Refat, Moamen S.

    2015-08-01

    This article describes the synthesis, characterization, computational and biological assessments of some divalent and trivalent metal (Ca(II), Fe(III), Pd(II) and Au(III)) complexes of nalidixic acid (nixH). The structures of these complexes were assigned using elemental analyses and spectral measurements e.g., IR, Raman, 1H NMR, 13C NMR and electronic techniques. These results indicated that, nalidixic acid reacts as a bidentate ligand bound to the metal ion through the oxygen atoms of carbonyl and carboxylate groups. The molar conductance measurements of the complexes in DMSO correspond to be non-electrolyte nature. Thus, these complexes may be formulated as [Ca(nix)(Cl)(H2O)3]. H2O, [Fe(nix)(Cl)2(H2O)2]·3H2O, [Pd(nix)(Cl)(H2O)] and [Au(nix)(Cl)2]. Base on the Coats-Redfern and Horowitz-Metzeger methods, the kinetic thermodynamic parameters (E∗, ΔS∗, ΔH∗ and ΔG∗) of the thermal decomposition reactions have been calculated from thermogravimetric curves of TG and DTG. The nano-scale range of the nalidixic acid complexes have been discussed using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) analyzer. The computational studies for the synthesized complexes have been estimated.

  6. Central metal ion exchange in a coordination polymer based on lanthanide ions and di(2-ethylhexyl)phosphoric acid: exchange rate and tunable affinity.

    PubMed

    Tasaki-Handa, Yuiko; Abe, Yukie; Ooi, Kenta; Tanaka, Mikiya; Wakisaka, Akihiro

    2014-01-01

    In this paper the exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) of di(2-ethylhexyl)phosphoric acid (Hdehp), [Ln(dehp)3], is studied. Kinetic and selectivity studies suggest that a polymeric network of [Ln(dehp)3] has different characteristics than the corresponding monomeric complex. The reaction rate is remarkably slow and requires over 600 h to reach in nearly equilibrium, and this can be explained by the polymeric crystalline structure and high valency of Ln(3+). The affinity of the exchange reaction reaches a maximum with the Ln(3+) possessing an ionic radius 7% smaller than that of the central Ln(3+), therefore, the affinity of the [Ln(dehp)3] is tunable based on the choice of the central metal ion. Such unique affinity, which differs from the monomeric complex, can be explained by two factors: the coordination preference and steric strain caused by the polymeric structure. The latter likely becomes predominant for Ln(3+) exchange when the ionic radius of the ion in solution is smaller than the original Ln(3+) by more than 7%. Structural studies suggest that the incoming Ln(3+) forms a new phase though an exchange reaction, and this could plausibly cause the structural strain.

  7. Amino acid-type interactions of L-3,4-dihydroxyphenylalanine with transition metal ions: An experimental and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Mandal, Shilpi; Das, Gunajyoti; Askari, Hassan

    2015-11-01

    This paper reports the synthesis of the Ni+2, Cu+2 and Zn+2 complexes of L-3,4-dihydroxyphenylalanine (L-dopa) using a solvent-free solid-state grinding procedure. The synthesized complexes are characterized by elemental, molar conductance, EDAX-SEM, TG/DTA, infrared, electronic absorption, fluorescence and XRD analyses; confirming a 1:2 metal-ligand stoichiometry of the complexes and involvement of the carboxyl and amino groups in complex formation. Phase-diagram and the kinetic parameters of the interactions between L-dopa and the metal ions are also explored. Molecular structures of the metal complexes are modeled within the framework of density functional theory in a vacuum and implicit aqueous environment using the most stable L-dopa conformers determined at the MP2/6-311++G(d,p) level. The gas and aqueous phase metal-binding affinities; theoretical IR and UV-vis spectral aspects; partial atomic charges; Wiberg bond indices; HOMO-LUMO energy gaps and dipole moments of the L-dopa conformers as well as their complexes are calculated and analyzed at B3LYP/6-311++G(d,p) level. The singlet state of the Ni(L-dopa)2 complex is found to be more favorable from thermodynamic perspectives as compared to the triplet state. Use of BHandHLYP and dispersion-corrected B3LYP (at DFT-D2 level) methods in conjugation with the 6-311++G(d,p) basis set affords us to accurately predict the binding affinity order of the three Lewis acids investigated, assess the influence of metal-aromatic π interactions on the thermodynamic stability of metalated L-dopa, and explore the effectiveness of the aforesaid methodologies in predicting a certain set of spectral and electronic properties of bioactive molecules. UV-vis titration and docking studies reveal that the metal complexes of L-dopa are able to bind to the surface of DNA.

  8. Diglycolamic acid modified silica gel for the separation of hazardous trivalent metal ions from aqueous solution.

    PubMed

    Suneesh, A S; Syamala, K V; Venkatesan, K A; Antony, M P; Vasudeva Rao, P R

    2015-01-15

    The surface of the silica gel was modified with diglycolamic acid moieties and the product (Si-DGAH) was characterized by elemental analysis, TG-DTA, (1)H and (29)Si NMR and scanning electron microscopy (SEM). The adsorption behavior of hazardous americium (III) and europium (III) in Si-DGAH was studied from aqueous nitric acid medium to examine the feasibility using the modified silica for the separation of Am(III) and Eu(III) from aqueous wastes. In this context, the effect of various parameters such as the duration of equilibration, and concentrations of europium, nitric acid, sodium nitrate and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase, on the distribution coefficient (K(d)) of Am(III) and Eu(III) was investigated. The distribution coefficient of ∼10(3) mL/g (>99.9% extraction) was obtained for both Am(III) and Eu(III) at pH 3, and the K(d) values decreased with increase in the concentration of nitric acid. Rapid kinetics of extraction in the initial stages of equilibration, followed by the establishment of equilibrium occurred within 30 min. The extraction data were fitted into Langmuir adsorption model and the apparent europium extraction capacity was determined. Europium loading capacity of the sorbent was determined at various feed pH by column method. The study indicated the possibility of using diglycolamic acid-modified silica for the separation of Eu(III) and Am(III) from aqueous wastes. PMID:25454425

  9. Sorption of metal ions on alumina

    SciTech Connect

    Baumgarten, E.; Kirchhausen-Duesing, U.

    1997-10-01

    The adsorption of metal ions on aluminas is of great interest in different fields such as geochemistry, oceanography, limnology, and pollution control. Precipitation and adsorption of metal ions (Co(II), Ni(II), Cu(II), and Cr(III)) on {gamma}-alumina were investigated experimentally. A surface chemical reaction model to calculate concentrations of aluminum ions, metal ions, and pH as variables depending on amount of alumina, volume of liquid and gas phase, initial metal concentration, and amount of acid or base added is presented. In the case of Co(II) the pH dependence of rest concentrations with and without alumina is equal; adsorption may be disregarded. For the other ions adsorption is important. Considering the charge of the surface does not improve the fit. In the pH region, where adsorption leads to lower rest concentrations than precipitation, adsorption may be described by a Henry isotherm.

  10. Aggregation of dialkyl-substituted diphosphonic acids and its effect on metal ion extraction.

    SciTech Connect

    Chiarizia, R.; Barrans, R. E., Jr.; Ferraro, J. R. Herlinger, A. W.; McAlister, D. R.

    1999-10-22

    Solvent extraction reagents containing the diphosphonic acid group exhibit an extraordinary affinity for tri-, tetra- and hexavalent actinides. Their use has been considered for actinide separation and pre-concentration procedures. Solvent extraction data obtained with P,P{prime}-di(2-ethylhexyl) methane-, ethane- and butanediphosphonic acids exhibit features that are difficult to explain without Knowledge of the aggregation state of the extractants. Information about the aggregation of the dialkyl-substituted diphosphonic acids in aromatic diluents has been obtained using the complementary techniques of vapor pressure osmometry (VPO), small angle neutron scattering (SANS), infrared spectroscopy and molecular mechanics. The results from these techniques provide an understanding of the aggregation behavior of these extractants that is fully compatible with the solvent extraction data. The most important results and their relevance to solvent extraction are reviewed in this paper.

  11. 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

  12. The enhancement of the hydrolysis of bamboo biomass in ionic liquid with chitosan-based solid acid catalysts immobilized with metal ions.

    PubMed

    Cheng, Jie; Wang, Nan; Zhao, Dezhou; Qin, Dandan; Si, Wenqing; Tan, Yunfei; Wei, Shun'an; Wang, Dan

    2016-11-01

    Three kinds of sulfonated cross-linked chitosan (SCCR) immobilized with metal ions of Cu(2+), Fe(3+) and Zn(2+) individually were synthesized and firstly used as solid acid catalysts in the hydrolysis of bamboo biomass. FTIR spectra showed that metal ions had been introduced into SCCR and the N-metal ions coordinate bound was formed. The particle sizes of these catalysts were about 500-1000μm with a pore size of 50-160μm. All of the three kinds of catalysts performed well for bamboo hydrolysis with 1-butyl-3-methyl-imidazolium chloride used as solvent. The most effective one was sulfonated cross-linked chitosan immobilized with Fe(3+) (Fe(3+)-SCCR). TRS yields were up to 73.42% for hydrolysis of bamboo powder in [C4mim]Cl with Fe(3+)-SCCR at 120°C and 20RPM after 24h. These novel chitosan-based metal ions immobilized solid acid catalysts with ionic liquids as the solvent might be promising to facilitate cost-efficient conversion of biomass into biofuels and bioproducts. PMID:27611029

  13. The enhancement of the hydrolysis of bamboo biomass in ionic liquid with chitosan-based solid acid catalysts immobilized with metal ions.

    PubMed

    Cheng, Jie; Wang, Nan; Zhao, Dezhou; Qin, Dandan; Si, Wenqing; Tan, Yunfei; Wei, Shun'an; Wang, Dan

    2016-11-01

    Three kinds of sulfonated cross-linked chitosan (SCCR) immobilized with metal ions of Cu(2+), Fe(3+) and Zn(2+) individually were synthesized and firstly used as solid acid catalysts in the hydrolysis of bamboo biomass. FTIR spectra showed that metal ions had been introduced into SCCR and the N-metal ions coordinate bound was formed. The particle sizes of these catalysts were about 500-1000μm with a pore size of 50-160μm. All of the three kinds of catalysts performed well for bamboo hydrolysis with 1-butyl-3-methyl-imidazolium chloride used as solvent. The most effective one was sulfonated cross-linked chitosan immobilized with Fe(3+) (Fe(3+)-SCCR). TRS yields were up to 73.42% for hydrolysis of bamboo powder in [C4mim]Cl with Fe(3+)-SCCR at 120°C and 20RPM after 24h. These novel chitosan-based metal ions immobilized solid acid catalysts with ionic liquids as the solvent might be promising to facilitate cost-efficient conversion of biomass into biofuels and bioproducts.

  14. Lanthanide ion exchange properties of a coordination polymer consisting of di(2-ethylhexyl) phosphoric acid and trivalent metal ions (Ce3+, Fe3+, or Al3+).

    PubMed

    Ooi, Kenta; Tasaki-Handa, Yuiko; Abe, Yukie; Wakisaka, Akihiko

    2014-03-28

    Three kinds of coordination polymers ([M(dehp)3], M = Ce, Fe, or Al) were prepared by mixing the sodium form (Na(dehp)) of di(2-ethylhexyl) phosphoric acid and MCl3 in an ethanol-water binary mixture. They have monoclinic crystalline structure with similar lattice parameters. The lanthanide ion (Ln(3+) = La(3+), Sm(3+), Dy(3+), or Yb(3+)) exchange properties were studied in a 20 : 80 vol% ethanol-water binary mixture containing 2 mM Ln(NO3)3 at room temperature. The rate of Ln(3+) adsorption is relatively slow; it requires over 3 weeks to reach equilibrium. [M(dehp)3] has different Ln(3+) affinities depending on the kind of central metal ions: the affinity order at 3 week adsorption is Yb(3+) < La(3+) < Dy(3+) < Sm(3+) for [Ce(dehp)3], La(3+) < Sm(3+) < Dy(3+) < Yb(3+) for [Fe(dehp)3], and La(3+) < Sm(3+), Dy(3+), Yb(3+) for [Al(dehp)3]. The difference in affinity order can be explained by two factors: the coordination preference and steric strain caused by the polymeric structure. The chemical and structural analyses suggested that the Ln(3+) adsorption progresses first by the central M(3+)/Ln(3+) exchange, followed by a morphological change to a rod-like or fibrous form by a solid phase reaction. In the case of [Fe(dehp)3], the eluted Fe(3+) may be hydrolyzed and precipitated as amorphous iron hydroxide.

  15. Acid-base and metal-ion binding properties of the RNA dinucleotide uridylyl-(5'-->3')-[5']uridylate (pUpU3-).

    PubMed

    Knobloch, Bernd; Suliga, Danuta; Okruszek, Andrzej; Sigel, Roland K O

    2005-07-01

    It is well known that Mg2+ and other divalent metal ions bind to the phosphate groups of nucleic acids. Subtle differences in the coordination properties of these metal ions to RNA, especially to ribozymes, determine whether they either promote or inhibit catalytic activity. The ability of metal ions to coordinate simultaneously with two neighboring phosphate groups is important for ribozyme structure and activity. However, such an interaction has not yet been quantified. Here, we have performed potentiometric pH titrations to determine the acidity constants of the protonated dinucleotide H2(pUpU)-, as well as the binding properties of pUpU3- towards Mg2+, Mn2+, Cd2+, Zn2+, and Pb2+. Whereas Mg2+, Mn2+, and Cd2+ only bind to the more basic 5'-terminal phosphate group, Pb2+, and to a certain extent also Zn2+, show a remarkably enhanced stability of the [M(pUpU)]- complex. This can be attributed to the formation of a macrochelate by bridging the two phosphate groups within this dinucleotide by these metal ions. Such a macrochelate is also possible in an oligonucleotide, because the basic structural units are the same, despite the difference in charge. The formation degrees of the macrochelated species of [Zn(pUpU)]- and [Pb(pUpU)]- amount to around 25 and 90 %, respectively. These findings are important in the context of ribozyme and DNAzyme catalysis, and explain, for example, why the leadzyme could be selected in the first place, and why this artificial ribozyme is inhibited by other divalent metal ions, such as Mg2+.

  16. Salicylic acid functionalized silica-coated magnetite nanoparticles for solid phase extraction and preconcentration of some heavy metal ions from various real samples

    PubMed Central

    2011-01-01

    A method for the preconcentration of trace heavy metal ions in environmental samples has been reported. The presented method is based on the sorption of Cu(II), Cd(II), Ni(II) and Cr(III) ions with salicylic acid as respective chelate on silica-coated magnetite nanoparticles. Prepared adsorbent was characterized by XRD, SEM, BET and FT-IR measurements. The metals content of the sorbed complexes are eluted using 4.0 mL of 1.0 mol L-1 nitric acid. The influences of the analytical parameters including pH, amount of solid phase and condition of eluting solution, the effects of matrix ions on the retention of the analytes were examined. The accuracy and precision of suggested method were tested by analyzing of certified reference materials. The detection limits (3Sb/m, N = 8) for Cu(II), Cd(II), Ni(II) and Cr(III) ions are 0.22, 0.11, 0.27 and 0.15 μg L-1, respectively, and the maximum preconcentration factor is 200. The method was successfully applied to the evaluation of these trace and toxic metals in various waters, foods and other samples. PMID:21762480

  17. Interrelationships among biological activity, disulfide bonds, secondary structure, and metal ion binding for a chemically synthesized 34-amino-acid peptide derived from alpha-fetoprotein.

    PubMed

    MacColl, R; Eisele, L E; Stack, R F; Hauer, C; Vakharia, D D; Benno, A; Kelly, W C; Mizejewski, G J

    2001-10-01

    A 34-amino-acid peptide has been chemically synthesized based on a sequence from human alpha-fetoprotein. The purified peptide is active in anti-growth assays when freshly prepared in pH 7.4 buffer at 0.20 g/l, but this peptide slowly becomes inactive. This functional change is proven by mass spectrometry to be triggered by the formation of an intrapeptide disulfide bond between the two cysteine residues on the peptide. Interpeptide cross-linking does not occur. The active and inactive forms of the peptide have almost identical secondary structures as shown by circular dichroism (CD). Zinc ions bind to the active peptide and completely prevents formation of the inactive form. Cobalt(II) ions also bind to the peptide, and the UV-Vis absorption spectrum of the cobalt-peptide complex shows that: (1) a near-UV sulfur-to-metal-ion charge-transfer band had a molar extinction coefficient consistent with two thiolate bonds to Co(II); (2) the lowest-energy visible d-d transition maximum at 659 nm, also, demonstrated that the two cysteine residues are ligands for the metal ion; (3) the d-d molar extinction coefficient showed that the metal ion-ligand complex was in a distorted tetrahedral symmetry. The peptide has two cysteines, and it is speculated that the other two metal ion ligands might be the two histidines. The Zn(II)- and Co(II)-peptide complexes had similar peptide conformations as indicated by their ultraviolet CD spectra, which differed very slightly from that of the free peptide. Surprisingly, the cobalt ions acted in the reverse of the zinc ions in that, instead of stabilizing anti-growth form of the peptide, they catalyzed its loss. Metal ion control of peptide function is a saliently interesting concept. Calcium ions, in the conditions studied, apparently do not bind to the peptide. Trifluoroethanol and temperature (60 degrees C) affected the secondary structure of the peptide, and the peptide was found capable of assuming various conformations in solution

  18. Influence of variable chemical conditions on EDTA-enhanced transport of metal ions in mildly acidic groundwater

    USGS Publications Warehouse

    Kent, D.B.; Davis, J.A.; Joye, J.L.; Curtis, G.P.

    2008-01-01

    Adsorption of Ni and Pb on aquifer sediments from Cape Cod, Massachusetts, USA increased with increasing pH and metal-ion concentration. Adsorption could be described quantitatively using a semi-mechanistic surface complexation model (SCM), in which adsorption is described using chemical reactions between metal ions and adsorption sites. Equilibrium reactive transport simulations incorporating the SCMs, formation of metal-ion-EDTA complexes, and either Fe(III)-oxyhydroxide solubility or Zn desorption from sediments identified important factors responsible for trends observed during transport experiments conducted with EDTA complexes of Ni, Zn, and Pb in the Cape Cod aquifer. Dissociation of Pb-EDTA by Fe(III) is more favorable than Ni-EDTA because of differences in Ni- and Pb-adsorption to the sediments. Dissociation of Ni-EDTA becomes more favorable with decreasing Ni-EDTA concentration and decreasing pH. In contrast to Ni, Pb-EDTA can be dissociated by Zn desorbed from the aquifer sediments. Variability in adsorbed Zn concentrations has a large impact on Pb-EDTA dissociation.

  19. Succinic acid-based leaching system: A sustainable process for recovery of valuable metals from spent Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Li; Qu, Wenjie; Zhang, Xiaoxiao; Lu, Jun; Chen, Renjie; Wu, Feng; Amine, Khalil

    2015-05-01

    A hydrometallurgical method involving natural organic acid leaching has been developed for recovery of lithium and cobalt from the cathode active materials in spent lithium-ion batteries. Succinic acid is employed as leaching agent and H2O2 as reductant. The cobalt and lithium contents from the succinic acid-based treatment of spent batteries are determined by inductively coupled plasma-optical emission spectroscopy to calculate the leaching efficiency. The spent LiCoO2 samples after calcination and the residues after leaching are characterized by X-ray diffraction and scanning electron microscopy. The results show that nearly 100% of cobalt and more than 96% of lithium are leached under optimal conditions: succinic acid concentration of 1.5 mol L-1, H2O2 content of 4 vol.%, solid-to-liquid ratio of 15 g L-1, temperature of 70 °C, and reaction time of 40 min. Results are also given for fitting of the experimental data to acid leaching kinetic models.

  20. 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.

  1. 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.

  2. 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.

  3. Enrichment of sulfate-reducing bacteria and resulting mineral formation in media mimicking pore water metal ion concentrations and pH conditions of acidic pit lakes.

    PubMed

    Meier, Jutta; Piva, Angela; Fortin, Danielle

    2012-01-01

    Acid mine drainage sites are extreme environments with high acidity and metal ion concentrations. Under anoxic conditions, microbial sulfate reduction may trigger the formation of secondary minerals as a result of H2S production and pH increase. This process was studied in batch experiments with enrichment cultures from acidic sediments of a pit lake using growth media set at different pH values and containing elevated concentrations of Fe²⁺ and Al³⁺. At initial pH values of 5 and 6, sulfate reduction occurred shortly after inoculation. Sulfate- reducing bacteria affiliated to the genus Desulfosporosinus predominated the microbial communities as shown by 16S rRNA gene analysis performed at the end of the incubation. At initial pH values of 3 and 4, sulfate reduction and cell growth occurred only after an extended lag phase, however, at a higher rate than in the less acidic assays. At the end of the growth phase, enrichments were dominated by Thermodesulfobium spp. suggesting that these sulfate reducers were better adapted to acidic conditions. Iron sulfides in the bulk phase were common in all assays, but specific aluminum precipitates formed in close association with cell surfaces and may function as a detoxification mechanism of dissolved Al species at low pH.

  4. The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water.

    PubMed

    Wiredu, Bernard; Amarasekara, Ananda S

    2015-01-01

    The effects of adding Cr(3+), Mn(2+), Fe(3+), Co(2+) Ni(2+), Cu(2+), Zn(2+) and La(3+) chlorides as co-catalysts to 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed saccharification of corn stover in aqueous medium was studied at 140-170 °C, by measuring the total reducing sugar (TRS) and glucose yields. The samples with Mn(2+), Fe(3+), Co(2+) as co-catalysts produced higher TRS yields compared to the sample without the metal ions. The Mn(2+) produced the highest catalytic effect enhancements and produced TRS yields of 68.0%, 72.9%, 90.2% and 87.9% at 140, 150, 160 and 170 °C respectively; whereas the corn stover samples without the Mn(2+) produced TRS yields of 42.9%, 52.3%, 54.4% and 53.5% at the same four temperatures. At higher temperatures of 160 and 170 °C, all metal ions studied produced significant enhancements in glucose yields, except Cr(3+). The addition of La(3+) as a co-catalyst produced the highest glucose yield improvement. PMID:25911191

  5. The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water.

    PubMed

    Wiredu, Bernard; Amarasekara, Ananda S

    2015-01-01

    The effects of adding Cr(3+), Mn(2+), Fe(3+), Co(2+) Ni(2+), Cu(2+), Zn(2+) and La(3+) chlorides as co-catalysts to 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed saccharification of corn stover in aqueous medium was studied at 140-170 °C, by measuring the total reducing sugar (TRS) and glucose yields. The samples with Mn(2+), Fe(3+), Co(2+) as co-catalysts produced higher TRS yields compared to the sample without the metal ions. The Mn(2+) produced the highest catalytic effect enhancements and produced TRS yields of 68.0%, 72.9%, 90.2% and 87.9% at 140, 150, 160 and 170 °C respectively; whereas the corn stover samples without the Mn(2+) produced TRS yields of 42.9%, 52.3%, 54.4% and 53.5% at the same four temperatures. At higher temperatures of 160 and 170 °C, all metal ions studied produced significant enhancements in glucose yields, except Cr(3+). The addition of La(3+) as a co-catalyst produced the highest glucose yield improvement.

  6. 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)

  7. Metal ion complexes of N,N'-bis(2-pyridylmethyl)-1,3-diaminopropane-N,N'-diacetic acid, H2bppd.

    PubMed

    Kissel, Daniel S; Florián, Jan; McLauchlan, Craig C; Herlinger, Albert W

    2014-04-01

    A higher yield synthesis of N,N'-bis(2-pyridylmethyl)-1,3-diaminopropane-N,N'-diacetic acid (H2bppd) and its complexation of trivalent metal ions (Al(III), Ga(III), In(III)) and selected lanthanides (Ln(III)) are reported. H2bppd and the metal-bppd(2-) complexes, isolated as hexafluorophosphate salts, were characterized by elemental analysis, mass spectrometry, IR, and (1)H and (13)C NMR spectroscopy. [Ga(bppd)]PF6, [Ga(C19H22N4O4)]PF6, was crystallized as colorless needles by slow evaporation from anhydrous methanol; its molecular structure was solved by direct X-ray crystallography methods. The compound crystallized in the monoclinic space group P21/c, with a = 9.6134(2) Å, b = 20.2505(4) Å, c = 11.6483(3) Å, β = 97.520(1)(o), and Z = 4. Ga is coordinated in a distorted octahedral geometry provided by a N4O2 donor atom set with cis-monodentate acetate groups and cis-2-pyridylmethyl N atoms. Quantum mechanical calculations were performed for the three possible geometric isomers of a pseudo-octahedral metal-bppd(2-) complex with five different metal ions. The results indicate, that in aqueous solution, the stability of the trans-O,O isomer is similar to that of the cis-O,O; cis-Npy,Npy isomer but is greater than that of the trans-Npy,Npy isomer. Calculations for a six-coordinate La(III)-bppd(2-) complex converge to a structure with a very large Npy-La-Npy bond angle (146.4°), a high metal charge (2.28 au), and a high solvation free energy (-79.4 kcal/mol). The most stable geometric arrangement for bppd(2-) around the larger La(III) is best described as an open nestlike structure with space available for additional ligands. IR spectroscopy was used to investigate the nature of the H2bppd-metal complexes isolated in the solid state and the binding modes of the carboxylate functionalities. The spectra indicate that fully deprotonated [M(bppd)](+) complexes as well as partially protonated complexes [M(Hbppd)Cl](+) were isolated. The (1)H and (13)C assignments for

  8. 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.

  9. Nucleic acids encoding metal uptake transporters and their uses

    DOEpatents

    Schroeder, Julian I.; Antosiewicz, Danuta M.; Schachtman, Daniel P.; Clemens, Stephan

    1999-01-01

    The invention provides LCT1 nucleic acids which encode metal ion uptake transporters. The invention also provides methods of modulating heavy metal and alkali metal uptake in plants. The methods involve producing transgenic plants comprising a recombinant expression cassette containing an LCT1 nucleic acid linked to a plant promoter.

  10. Quantitative Phosphoproteome Analysis of Lysophosphatidic Acid Induced Chemotaxis applying Dual-step ¹⁸O Labeling Coupled with Immobilized Metal-ion Affinity Chromatography

    SciTech Connect

    Ding, Shi-Jian; Wang, Yingchun; Jacobs, Jon M.; Qian, Weijun; Yang, Feng; Tolmachev, Aleksey V.; Du, Xiuxia; Wang, Wei; Moore, Ronald J.; Monroe, Matthew E.; Purvine, Samuel O.; Waters, Katrina M.; Heibeck, Tyler H.; Adkins, Joshua N.; Camp, David G.; Klemke, Richard L.; Smith, Richard D.

    2008-10-01

    Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in a variety of different cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its applications for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed 16O/18O labeling plus 16O/18O-methanol esterification labeling for quantitation, a macro- Immobilized Metal-ion Affinity Chromatography trap for phosphopeptide enrichment, and a monolithic capillary column with integrated electrospray emitter. LC separation and MS/MS is followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer and complementary searching algorithms for interpreting MS/MS spectra. Protein phosphorylation involved in various signaling pathways of cell migration were identified and quantified, such as mitogen-activated protein kinase 1, dual-specificity mitogen-activated protein kinase kinase 2, and dual-specificity tyrosine-phosphorylation regulated kinase 1b, and a number of Rho GTPase-activating proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with gradient sensing and cell chemotaxis.

  11. Ultrafine metal particles immobilized on styrene/acrylic acid copolymer particles

    SciTech Connect

    Tamai, Hisashi; Hamamoto, Shiro; Nishiyama, Fumitaka; Yasuda, Hajime

    1995-04-01

    Ultrafine metal particles immobilized on styrene/acrylic acid copolymer fine particles were produced by reducing the copolymer particles-metal ion complexes or refluxing an ethanol solution of metal ions in the presence of copolymer particles. The size of metal particles formed by reduction of the complex is smaller than that by reflux of the metal ion solution and depends on the amount of metal ions immobilized.

  12. 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.

  13. Hydrated metal ions in the gas phase.

    PubMed

    Beyer, Martin K

    2007-01-01

    Studying metal ion solvation, especially hydration, in the gas phase has developed into a field that is dominated by a tight interaction between experiment and theory. Since the studied species carry charge, mass spectrometry is an indispensable tool in all experiments. Whereas gas-phase coordination chemistry and reactions of bare metal ions are reasonably well understood, systems containing a larger number of solvent molecules are still difficult to understand. This review focuses on the rich chemistry of hydrated metal ions in the gas phase, covering coordination chemistry, charge separation in multiply charged systems, as well as intracluster and ion-molecule reactions. Key ideas of metal ion solvation in the gas phase are illustrated with rare-gas solvated metal ions.

  14. Discriminating Properties of Alkali Metal Ions Towards the Constituents of Proteins and Nucleic Acids. Conclusions from Gas-Phase and Theoretical Studies.

    PubMed

    Rodgers, Mary T; Armentrout, Peter B

    2016-01-01

    Quantitative insight into the structures and thermodynamics of alkali metal cations interacting with biological molecules can be obtained from studies in the gas phase combined with theoretical work. In this chapter, the fundamentals of the experimental and theoretical techniques are first summarized and results for such work on complexes of alkali metal cations with amino acids, small peptides, and nucleobases are reviewed. Periodic trends in how these interactions vary as the alkali metal cations get heavier are highlighted.

  15. Ion exchange selectivity for cross-linked polyacrylic acid

    NASA Technical Reports Server (NTRS)

    May, C. E.; Philipp, W. H.

    1983-01-01

    The ion separation factors for 21 common metal ions with cross-linked polyacrylic acid were determined as a function of pH and the percent of the cross-linked polyacrylic acid neutralized. The calcium ion was used as a reference. At a pH of 5 the decreasing order of affinity of the ions for the cross-linked polyacrylic acid was found to be: Hg++, Fe+++, Pb++, Cr+++, Cu++, Cd++, Al+++, Ag+, Zn++, Ni++, Mn++, Co++, Ca++, Sr++, Ba++, Mg++, K+, Rb+, Cs+, Na+, and Li+. Members of a chemical family exhibited similar selectivities. The Hg++ ion appeared to be about a million times more strongly bound than the alkali metal ions. The relative binding of most of the metal ions varied with pH; the very tightly and very weakly bound ions showed the largest variations with pH. The calcium ion-hydrogen ion equilibrium was perturbed very little by the presence of the other ions. The separation factors and selectivity coefficients are discussed in terms of equilibrium and thermodynamic significance.

  16. Effect of metal ions on the reactions of the cumyloxyl radical with hydrogen atom donors. Fine control on hydrogen abstraction reactivity determined by Lewis acid-base interactions.

    PubMed

    Salamone, Michela; Mangiacapra, Livia; DiLabio, Gino A; Bietti, Massimo

    2013-01-01

    A time-resolved kinetic study on the effect of metal ions (M(n+)) on hydrogen abstraction reactions from C-H donor substrates by the cumyloxyl radical (CumO(•)) was carried out in acetonitrile. Metal salt addition was observed to increase the CumO(•) β-scission rate constant in the order Li(+) > Mg(2+) > Na(+). These effects were explained in terms of the stabilization of the β-scission transition state determined by Lewis acid-base interactions between M(n+) and the radical. When hydrogen abstraction from 1,4-cyclohexadiene was studied in the presence of LiClO(4) and Mg(ClO(4))(2), a slight increase in rate constant (k(H)) was observed indicating that interaction between M(n+) and CumO(•) can also influence, although to a limited extent, the hydrogen abstraction reactivity of alkoxyl radicals. With Lewis basic C-H donors such as THF and tertiary amines, a decrease in k(H) with increasing Lewis acidity of M(n+) was observed (k(H)(MeCN) > k(H)(Li(+)) > k(H)(Mg(2+))). This behavior was explained in terms of the stronger Lewis acid-base interaction of M(n+) with the substrate as compared to the radical. This interaction reduces the degree of overlap between the α-C-H σ* orbital and a heteroatom lone-pair, increasing the C-H BDE and destabilizing the carbon centered radical formed after abstraction. With tertiary amines, a >2-order of magnitude decrease in k(H) was measured after Mg(ClO(4))(2) addition up to a 1.5:1 amine/Mg(ClO(4))(2) ratio. At higher amine concentrations, very similar k(H) values were measured with and without Mg(ClO(4))(2). These results clearly show that with strong Lewis basic substrates variations in the nature and concentration of M(n+) can dramatically influence k(H), allowing for a fine control of the substrate hydrogen atom donor ability, thus providing a convenient method for C-H deactivation. The implications and generality of these findings are discussed.

  17. Evaluating the role of metal ions in the bathochromic and hyperchromic responses of cyanidin derivatives in acidic and alkaline pH.

    PubMed

    Sigurdson, G T; Robbins, R J; Collins, T M; Giusti, M M

    2016-10-01

    In many food products, colorants derived from natural sources are increasingly popular due to consumer demand. Anthocyanins are one class of versatile and abundant naturally occurring chromophores that produce different hues in nature, especially with metal ions and other copigments assisting. The effects of chelation of metal ions (Mg(2+), Al(3+), Cr(3+), Fe(3+), and Ga(3+)) in factorial excesses to anthocyanin concentration (0-500×) on the spectral characteristics (380-700nm) of cyanidin and acylated cyanidin derivatives were evaluated to better understand the color evolution of anthocyanin-metal chelates in pH 3-8. In all pH, anthocyanins exhibited bathochromic and hyperchromic shifts. Largest bathochromic shifts most often occurred in pH 6; while largest hyperchromic shifts occurred in pH 5. Divalent Mg(2+) showed no observable effect on anthocyanin color while trivalent metal ions caused bathochromic shifts and hue changes. Generally, bathochromic shifts on anthocyanins were greatest with more electron rich metal ions (Fe(3+)≈Ga(3+)>Al(3+)>Cr(3+)).

  18. Evaluating the role of metal ions in the bathochromic and hyperchromic responses of cyanidin derivatives in acidic and alkaline pH.

    PubMed

    Sigurdson, G T; Robbins, R J; Collins, T M; Giusti, M M

    2016-10-01

    In many food products, colorants derived from natural sources are increasingly popular due to consumer demand. Anthocyanins are one class of versatile and abundant naturally occurring chromophores that produce different hues in nature, especially with metal ions and other copigments assisting. The effects of chelation of metal ions (Mg(2+), Al(3+), Cr(3+), Fe(3+), and Ga(3+)) in factorial excesses to anthocyanin concentration (0-500×) on the spectral characteristics (380-700nm) of cyanidin and acylated cyanidin derivatives were evaluated to better understand the color evolution of anthocyanin-metal chelates in pH 3-8. In all pH, anthocyanins exhibited bathochromic and hyperchromic shifts. Largest bathochromic shifts most often occurred in pH 6; while largest hyperchromic shifts occurred in pH 5. Divalent Mg(2+) showed no observable effect on anthocyanin color while trivalent metal ions caused bathochromic shifts and hue changes. Generally, bathochromic shifts on anthocyanins were greatest with more electron rich metal ions (Fe(3+)≈Ga(3+)>Al(3+)>Cr(3+)). PMID:27132820

  19. Metal ion blockage of tritium incorporation into gamma-carboxyglutamic acid of prothrombin. Stoichiometry of gamma-carboxyglutamic acid to Gd3+ for the high affinity sites

    SciTech Connect

    Bajaj, S.P.; Saini, R.; Katz, A.; Cai, G.Z.; Maki, S.L.; Brodsky, G.L.

    1988-07-15

    Prothrombin possesses two high affinity and four low affinity gamma-carboxyglutamic acid (Gla)-dependent gadolinium binding sites. Earlier work has shown that tritium can be specifically incorporated at the gamma-carbon of Gla in proteins at pH 5. In the present work we show that inclusion of saturating concentrations of Ca2+ in nondenaturing buffer systems ranging from pH 5.5 to 8.5 prevents the exchange of tritium into all 10 Gla residues of prothrombin. Similarly, saturating concentrations of Gd3+ prevent tritium incorporation into Gla at pH 5.5. Positive cooperativity was observed for the binding of Gd3+ to human prothrombin (at pH 5.5) for the two high affinity sites (Kd congruent to 35 nM). The four low affinity sites bind Gd3+ with a Kd congruent to 5 microM. Incubation of prothrombin ranging in concentrations from 10 to 40 microM with 2 eq of Gd3+ at pH 5.5 prevents 5.7 (average of seven determinations) Gla residues from tritium incorporation. Sedimentation velocity experiments conducted at pH 5.5 indicate that prothrombin in the presence of saturating concentrations of Gd3+ polymerizes, most likely, to a trimer. Further, in the presence of 2 eq of Gd3+, calculated percent weight average concentration of monomer prothrombin is congruent to 100% at 10 microM, approximately equal to 95% at 20 microM, and congruento to 80% at 40 microM protein concentration. Thus, it appears that under conditions in which prothrombin primarily exists as a monomer, occupancy of the initial two metal binding sites by Gd3+ involves six Gla residues.

  20. Metal Ions Analysis with Capillary Zone Electrophoresis.

    PubMed

    Malik, Ashok Kumar; Aulakh, Jatinder Singh; Kaur, Varinder

    2016-01-01

    Capillary electrophoresis has recently attracted considerable attention as a promising analytical technique for metal ion separations. Significant advances that open new application areas for capillary electrophoresis in the analysis of metal species occurred based on various auxiliary separation principles. These are mainly due to complexation, ion pairing, solvation, and micellization interactions between metal analytes and electrolyte additives, which alter the separation selectivity in a broad range. Likewise, many separation studies for metal ions have been concentrated on the use of preelectrophoresis derivatization methodology. Approaches suitable for manipulation of selectivity for different metal species including metal cations, metal complexes, metal oxoanions, and organometallic compounds, are discussed, with special attention paid to the related electrophoretic system variables using illustrative examples. PMID:27645740

  1. 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.

  2. Inosylyl(3'-->5')inosine (IpI-). Acid-base and metal ion-binding properties of a dinucleoside monophosphate in aqueous solution.

    PubMed

    Knobloch, Bernd; Okruszek, Andrzej; Sigel, Helmut

    2008-04-01

    The acidity constants of the (N7)H(+) sites of inosylyl(3'-->5')inosine (IpI(-)) were estimated and those of its (N1)H sites were measured by potentiometric pH titrations in aqueous solution (25 degrees C; I = 0.1 M, NaNO3). The same method was used for the determination of the stability constants of the 1:1 complexes formed between Mg(2+), Co(2+), Ni(2+), Zn(2+), or Cd(2+) (= M(2+)) and (IpI - H)(2-) and, in the case of Mg(2+), also of (IpI - 2H)(3-). The stability constants of the M(IpI)(+) complexes were estimated. The acidity constants of H(inosine)(+) and the stability constants of the M(Ino)(2+) and M(Ino - H)(+) complexes were taken from the literature. The comparison of these and related data allows the conclusion that, in the M(IpI - H) species, chelates are formed; most likely they are preferably of an N7/N7 type. For the metal ions Co(2+), Ni(2+), Zn(2+), or Cd(2+), the formation degrees of the chelates are on the order of 60-80%; no chelates could be detected for the Mg(IpI - H) complexes. It is noteworthy that the (N1)H deprotonation, which leads to the M(IpI - H) species, occurs in all M(IpI)(+) complexes in the physiological pH range of about 7.5 or even below.

  3. 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.

  4. An isotope (18O, 15N, and 2H) technique to investigate the metal ion interactions between the phosphoryl group and amino acid side chains by electrospray ionization mass spectrometry.

    PubMed

    Gao, Xiang; Hu, Xiaomei; Zhu, Jun; Zeng, Zhiping; Han, Daxiong; Tang, Guo; Huang, Xiantong; Xu, Pengxiang; Zhao, Yufen

    2011-04-01

    Cationic metal ion-coordinated N-diisopropyloxyphosphoryl dipeptides (DIPP-dipeptides) were analyzed by electrospray ionization multistage tandem mass spectrometry (ESI-MS(n)). Two novel rearrangement reactions with hydroxyl oxygen or carbonyl oxygen migrations were observed in ESI-MS/MS of the metallic adducts of DIPP-dipeptides, but not for the corresponding protonated DIPP-dipeptides. The possible oxygen migration mechanisms were elucidated through a combination of MS/MS experiments, isotope ((18)O, (15)N, and (2)H) labeling, accurate mass measurements, and density functional theory (DFT) calculations at the B3LYP/6-31 G(d) level. It was found that lithium and sodium cations catalyze the carbonyl oxygen migration more efficiently than does potassium and participation through a cyclic phosphoryl intermediate. In addition, dipeptides having a C-terminal hydroxyl or aromatic amino acid residue show a more favorable rearrangement through carbonyl oxygen migration, which may be due to metal cation stabilization by the donation of lone pair of the hydroxyl oxygen or aromatic π-electrons of the C-terminal amino acid residue, respectively. It was further shown that the metal ions, namely lithium, sodium, and potassium cations, could play a novel directing role for the migration of hydroxyl or carbonyl oxygen in the gas phase. This discovery suggests that interactions between phosphorylated biomolecules and proteins might involve the assistance of metal ions to coordinate the phosphoryl oxygen and protein side chains to achieve molecular recognition.

  5. Separation of metal ions from aqueous solutions

    SciTech Connect

    Almon, A.

    1991-12-31

    This invention is comprised of 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 flowing cell containing flowing 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 flowing cell and connected to the electrodes, and optionally a detector such as a chromatographic detector, positioned outside the flowing cell. This apparatus and its operation has significant application where trace amounts of metal ions are to be separated.

  6. 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.

  7. Metal ion removal from aqueous solution using physic seed hull.

    PubMed

    Mohammad, Masita; Maitra, Saikat; Ahmad, Naveed; Bustam, Azmi; Sen, T K; Dutta, Binay K

    2010-07-15

    The potential of physic seed hull (PSH), Jantropha curcas L. as an adsorbent for the removal of Cd(2+) and Zn(2+) metal ions from aqueous solution has been investigated. It has been found that the amount of adsorption for both Cd(2+) and Zn(2+) increased with the increase in initial metal ions concentration, contact time, temperature, adsorbent dosage and the solution pH (in acidic range), but decreased with the increase in the particle size of the adsorbent. The adsorption process for both metal ions on PSH consists of three stages-a rapid initial adsorption followed by a period of slower uptake of metal ions and virtually no uptake at the final stage. The kinetics of metal ions adsorption on PSH followed a pseudo-second-order model. The adsorption equilibrium data were fitted in the three adsorption isotherms-Freundlich, Langmuir and Dubinin-Radushkevich isotherms. The data best fit in the Langmuir isotherm indication monolayer chemisorption of the metal ions. The adsorption capacity of PSH for both Zn(2+) and Cd(2+) was found to be comparable with other available adsorbents. About 36-47% of the adsorbed metal could be leached out of the loaded PSH using 0.1M HCl as the eluting medium. PMID:20362390

  8. Effect of water, metallic ions, fatty acid and temperature on oxidative stability of 1-octacosanol from sugarcane rind.

    PubMed

    Feng, Simin; Luo, Zisheng; Zeng, Fangfang; Liu, Songbai; Khan, Zia Ullah

    2015-09-01

    The chemical composition and selected physical parameters of crude 1-octacosanol (1-OC) extracted from sugarcane rind have been determined. GC-MS results exhibited that 1-OC sample was primarily composed of 1-OC (45.17%), 1-docosene (12.04%), 1-triacontanol (0.23%), 1-heneicosanol (0.33%), 1-tetracosanal (0.28%), campesterol (4.5%), stigmasterol (9.12%) and β-sitosterol (8.23%). The linoleic acid had important effects on physical and chemical properties of 1-OC sample, as it notably changed the melting point and the onset oxidation temperature To of 1-OC sample from 83.75 ± 0.35 °C to 63.25 ± 0.35 °C and 245.64 ± 2.04 °C to 160.03 ± 0.01 °C, respectively. It was also proved that the oxidation reactions were significantly different at different temperature levels. 1-OC was stable up to 245.64 ± 2.04 °C. However, when the temperature continued to rise, 1-OC and its oxidation products started to be oxidized. Therefore, attention should be paid to the quality of 1-OC during the preparation of food and to minimize the undesirable breakdown products.

  9. Effect of water, metallic ions, fatty acid and temperature on oxidative stability of 1-octacosanol from sugarcane rind.

    PubMed

    Feng, Simin; Luo, Zisheng; Zeng, Fangfang; Liu, Songbai; Khan, Zia Ullah

    2015-09-01

    The chemical composition and selected physical parameters of crude 1-octacosanol (1-OC) extracted from sugarcane rind have been determined. GC-MS results exhibited that 1-OC sample was primarily composed of 1-OC (45.17%), 1-docosene (12.04%), 1-triacontanol (0.23%), 1-heneicosanol (0.33%), 1-tetracosanal (0.28%), campesterol (4.5%), stigmasterol (9.12%) and β-sitosterol (8.23%). The linoleic acid had important effects on physical and chemical properties of 1-OC sample, as it notably changed the melting point and the onset oxidation temperature To of 1-OC sample from 83.75 ± 0.35 °C to 63.25 ± 0.35 °C and 245.64 ± 2.04 °C to 160.03 ± 0.01 °C, respectively. It was also proved that the oxidation reactions were significantly different at different temperature levels. 1-OC was stable up to 245.64 ± 2.04 °C. However, when the temperature continued to rise, 1-OC and its oxidation products started to be oxidized. Therefore, attention should be paid to the quality of 1-OC during the preparation of food and to minimize the undesirable breakdown products. PMID:25842324

  10. 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.

  11. 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+}.

  12. Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.

    PubMed

    Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan

    2014-04-29

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  13. Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.

    PubMed

    Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan

    2014-04-29

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory. PMID:24702119

  14. Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater.

    PubMed

    Han, Weijiang; Fu, Fenglian; Cheng, Zihang; Tang, Bing; Wu, Shijiao

    2016-01-25

    The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+) was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+) were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+)) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed.

  15. Aging, genetics, and the environment: potential of errors introduced into genetic information transfer by metal ions.

    PubMed

    Eichhorn, G L

    1979-02-01

    Metal ions, which are introduced into living organisms from the environment, are required in every aspect of genetic information transfer. However, the "wrong" metal ion, or even the "right" metal ion in the wrong concentration, can produce deleterious information transfer effects. Metal ions react with nucleic acids in many different ways, and virtually all of these reactions effect major changes in the structure of the nucleic acids. Cellular metal ion concentrations change with age. The effects of such concentration changes on genetic information transfer suggest the possibility that metal ions can influence the aging process. A specific example of such influence is the accumulation in brain cells of aluminum ions, which may have a relationship to Alzheimer's disease.

  16. Structural modifications in biosynthetic melanins induced by metal ions.

    PubMed

    Palumbo, A; d'Ischia, M; Misuraca, G; Prota, G; Schultz, T M

    1988-02-17

    A number of transition metal ions with a wide distribution in biological systems, e.g., Cu2+, Co2+ and Zn2+, are shown to affect markedly the chemical properties of melanins formed by the tyrosinase-catalysed oxidation of dopa. Acid decarboxylation and permanganate degradation provide evidence that melanins prepared in the presence of metal ions contain a high content of carboxyl groups arising from the incorporation of 5,6-dihydroxyindole-2-carboxylic acid (DICA) into the pigment polymer. Naturally occurring melanins from cephalopod ink and B16 mouse melanoma were found to be much more similar to melanins prepared in the presence of metal ions than to standard melanins prepared in the absence of metal ions. These results suggest that the presence of carboxylated indole units in natural melanins is probably due to the intervention in the biochemical pathway of metal ions which, as recently shown, catalyse the formation of DICA versus 5,6-dihydroxyindole in the rearrangement of dopachrome. PMID:3124888

  17. Recovery of metal ions by microfungal filters.

    PubMed

    Wales, D S; Sagar, B F

    1990-01-01

    Many microfungi contain chitin/chitosan as an integral part of the cell wall structure. The binding of toxic and heavy metal ions by chitosan or partly deacetylated chitin is a direct consequence of the base strength of the primary amine group and is most effective for those metals that form complexes with ammonia. Of the microfungi studied, hyphae from Mucor mucedo and Rhizomucor miehei, after treatment with hydroxide to expose the chitin/chitosan, were found to be most effective in the capture of metal ions. Chemically treated mycelia have so far been shown to bind silver, zinc, lead, copper, nickel, cobalt, cadmium, iron and chromium, with the efficiency of metal-ion binding apparently being inversely proportional to the valency state of the metal ions to be bound. Wet-laid papers produced from mixed slurries of treated mycelia and various conventional paper-making and textile fibres have exceptionally good tensile- and bursting-strength properties, particularly in the wet state. Papers containing 1 g treated mycelia removed up to 90% of various metal ions in solution (50 cm3, 1.5 mmol dm-3) with flow rates of 0.5 cm3 cm-2 min-1. However, the total metal-ion binding capacities of single-thickness microfungal papers are limited under constant flow conditions. The total volume flowing through the system before metal-ion breakthrough occurs increases in direct proportion to the number of sheets of microfungal paper but the concomitant reduction in flow rates becomes a limiting factor. Mycelia-containing structures that allow efficient metal-ion binding at commercially acceptable flow rates are currently being investigated.

  18. Lewis Acid Coupled Electron Transfer of Metal-Oxygen Intermediates.

    PubMed

    Fukuzumi, Shunichi; Ohkubo, Kei; Lee, Yong-Min; Nam, Wonwoo

    2015-12-01

    Redox-inactive metal ions and Brønsted acids that function as Lewis acids play pivotal roles in modulating the redox reactivity of metal-oxygen intermediates, such as metal-oxo and metal-peroxo complexes. The mechanisms of the oxidative CH bond cleavage of toluene derivatives, sulfoxidation of thioanisole derivatives, and epoxidation of styrene derivatives by mononuclear nonheme iron(IV)-oxo complexes in the presence of triflic acid (HOTf) and Sc(OTf)3 have been unified as rate-determining electron transfer coupled with binding of Lewis acids (HOTf and Sc(OTf)3 ) by iron(III)-oxo complexes. All logarithms of the observed second-order rate constants of Lewis acid-promoted oxidative CH bond cleavage, sulfoxidation, and epoxidation reactions of iron(IV)-oxo complexes exhibit remarkably unified correlations with the driving forces of proton-coupled electron transfer (PCET) and metal ion-coupled electron transfer (MCET) in light of the Marcus theory of electron transfer when the differences in the formation constants of precursor complexes were taken into account. The binding of HOTf and Sc(OTf)3 to the metal-oxo moiety has been confirmed for Mn(IV) -oxo complexes. The enhancement of the electron-transfer reactivity of metal-oxo complexes by binding of Lewis acids increases with increasing the Lewis acidity of redox-inactive metal ions. Metal ions can also bind to mononuclear nonheme iron(III)-peroxo complexes, resulting in acceleration of the electron-transfer reduction but deceleration of the electron-transfer oxidation. Such a control on the reactivity of metal-oxygen intermediates by binding of Lewis acids provides valuable insight into the role of Ca(2+) in the oxidation of water to dioxygen by the oxygen-evolving complex in photosystem II.

  19. Gas and metal ion sources

    SciTech Connect

    Oaks, E. |; Yushkov, G.

    1996-08-01

    The positive ion sources are now of interest owing to both their conventional use, e.g., as injectors in charged-particle accelerators and the promising capabilities of intense ion beams in the processes related to the action of ions on various solid surfaces. For industrial use, the sources of intense ion beams and their power supplies should meet the specific requirements as follows: They should be simple, technologically effective, reliable, and relatively low-cost. Since the scanning of an intense ion beam is a complicated problem, broad ion beams hold the greatest promise. For the best use of such beams it is desirable that the ion current density be uniformly distributed over the beam cross section. The ion beam current density should be high enough for the treatment process be accomplished for an acceptable time. Thus, the ion sources used for high-current, high-dose metallurgical implantation should provide for gaining an exposure dose of {approximately} 10{sup 17} cm{sup {minus}2} in some tens of minutes. So the average ion current density at the surface under treatment should be over 10{sup {minus}5} A/cm{sup 2}. The upper limit of the current density depends on the admissible heating of the surface under treatment. The accelerating voltage of an ion source is dictated by its specific use; it seems to lie in the range from {approximately}1 kV (for the ion source used for surface sputtering) to {approximately}100 kV and over (for the ion sources used for high-current, high-dose metallurgical implantation).

  20. Specific chemical interactions between metal ions and biological solids exemplified by sludge particulates.

    PubMed

    Huang, C P; Wang, Jianmin

    2014-05-01

    The adsorption of metals onto biological surfaces was studied exemplified by municipal sludge particulates of the primary, the secondary, and the tertiary sludge types from four regional wastewater treatment plants. Major factors affecting the extent of metal adsorption including pH, DOM, total biomass, and total metal loading were studied. The acidity-basicity characteristics of the DOM, the metal ions (Lewis acids), and the surface of the sludge particulates make pH the most important parameter in metal adsorption. Change in pH can modify the speciation of the metal ions, the DOM, and the surface acidity of the sludge particulates and subsequently determines the degree of metal distribution between the aqueous phase and the sludge solids. Information on the acidity-basicity characteristics of the DOM and the sludge particulates are used to calculate the stability constant of metal ion-sludge complexes.

  1. 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 ...

  2. 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.

  3. 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.

  4. Ab Initio Molecular Dynamics Study on the Interactions between Carboxylate Ions and Metal Ions in Water.

    PubMed

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Trinh, Thuat T; Grimes, Brian A

    2015-08-20

    The interaction between a carboxylate anion (deprotonated propanoic acid) and the divalent Mg(2+), Ca(2+), Sr(2+), Ba(2+) metal ions is studied via ab initio molecular dynamics. The main focus of the study is the selectivity of the carboxylate-metal ion interaction in aqueous solution. The interaction is modeled by explicitly accounting for the solvent molecules on a DFT level. The hydration energies of the metal ions along with their diffusion and mobility coefficients are determined and a trend correlated with their ionic radius is found. Subsequently, a series of 16 constrained molecular dynamics simulations for every ion is performed, and the interaction free energy is obtained from thermodynamic integration of the forces between the metal ion and the carboxylate ion. The results indicate that the magnesium ion interacts most strongly with the carboxylate, followed by calcium, strontium, and barium. Because the interaction free energy is not enough to explain the selectivity of the reaction observed experimentally, more detailed analysis is performed on the simulation trajectories to understand the steric changes in the reaction complex during dissociation. The solvent dynamics appear to play an important role during the dissociation of the complex and also in the observed selectivity behavior of the divalent ions.

  5. Mechanistic characterization of the HDV genomic ribozyme: solvent isotope effects and proton inventories in the absence of divalent metal ions support C75 as the general acid.

    PubMed

    Cerrone-Szakal, Andrea L; Siegfried, Nathan A; Bevilacqua, Philip C

    2008-11-01

    The hepatitis delta virus (HDV) ribozyme uses the nucleobase C75 and a hydrated Mg(2+) ion as the general acid-base catalysts in phosphodiester bond cleavage at physiological salt. A mechanistic framework has been advanced that involves one Mg(2+)-independent and two Mg(2+)-dependent channels. The rate-pH profile for wild-type (WT) ribozyme in the Mg(2+)-free channel is inverted relative to the fully Mg(2+)-dependent channel, with each having a near-neutral pKa. Inversion of the rate-pH profile was used as the crux of a mechanistic argument that C75 serves as general acid both in the presence and absence of Mg(2+). However, subsequent studies on a double mutant (DM) ribozyme suggested that the pKa observed for WT in the absence of Mg(2+) arises from ionization of C41, a structural nucleobase. To investigate this further, we acquired rate-pH/pD profiles and proton inventories for WT and DM in the absence of Mg(2+). Corrections were made for effects of ionic strength on hydrogen ion activity and pH meter readings. Results are accommodated by a model wherein the Mg(2+)-free pKa observed for WT arises from ionization of C75, and DM reactivity is compromised by protonation of C41. The Brønsted base appears to be water or hydroxide ion depending on pH. The observed pKa's are related to salt-dependent pH titrations of a model oligonucleotide, as well as electrostatic calculations, which support the local environment for C75 in the absence of Mg(2+) being similar to that in the presence of Mg(2+) and impervious to bulk ions. Accordingly, the catalytic role of C75 as the general acid does not appear to depend on divalent ions or the identity of the Brønsted base.

  6. Metal vapor arc ion plating

    SciTech Connect

    Bertram, L.A.; Fisher, R.W.; Mattox, D.M.; Zanner, F.J.

    1986-09-09

    A method and apparatus for ion plating are described. The apparatus uses more negative than a first electrode voltage in a vacuum arc remelt system to attract low energy ions from the anode electrode to the article to be plated. 2 figs.

  7. Chelation and foam separation of metal ions from solutions

    SciTech Connect

    Carleson, T.E.; Moussavi, M.

    1988-08-01

    An experimental study was conducted on the chelation and foam separation of trace amounts of cadmium, zinc, and lead from their water solutions. The chelation agents ethylenediaminetetraacetate (sodium salt), sodium diethyldithiocarbamate, and citric acid were used with sodium dodecylsulfate (SDS) as a foam-producing agent. The chelation agents did not produce metal complexes that were very surface active. The foam-producing agent produced metal ion complexes that were surface active and resulted in appreciable separation of the metal ions. The use of 100 ppm SDS resulted in separation of 90% of the zinc ions from solution containing 2 to 20 ppm zinc. At concentrations below and above this, the removal efficiency dropped significantly.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. Competitive complexation of metal ions with humic substances.

    PubMed

    Zhou, Ping; Yan, Hui; Gu, Baohua

    2005-03-01

    The surface complexation model was applied to simulate the competitive complexation of Ni, Ca and Al with humic substances. The presence of two types of binding sites in humic acid, carboxylic and phenolic functional groups, were assumed at both low and high pH conditions. Potentiometric titrations were used to characterize the intrinsic acidity constants of the two binding sites and their concentrations. It was found that the diffuse-layer model (DLM) could fit the experimental data well under different experimental conditions. Ni and Ca ions strongly compete with each other for reactions with the humic acid but Al showed little influence on the complexation of either Ni or Ca due to its hydrolysis and precipitation at pH approximately 5. The surface complexation constants determined from the mono-element systems were compared with those obtained from the multiple-element system (a mixture of the three metal ions). Results indicate little changes in the intrinsic surface complexation constants. Modeling results also indicate that high concentrations of Ca in the contaminated groundwater could strongly inhibit the complexation of Ni ions whereas an increase in pH and the humic concentration could attenuate such competitive interactions. The present study suggests that the surface complexation model could be useful in predicting interactions of the metal ions with humic substances and potentially aid in the design of remediation strategies for metal-contaminated soil and groundwater.

  14. Metal ions doped chitosan-poly(acrylic acid) nanospheres: Synthesis and their application in simultaneously electrochemical detection of four markers of pancreatic cancer.

    PubMed

    Rong, Qinfeng; Feng, Feng; Ma, Zhanfang

    2016-01-15

    In this work, a one-pot method was designed to synthesize copper ions, cadmium ions, lead ions and zinc ions doped chitosan-poly(acrylic acid) nanospheres. Those nanospheres can not only produce independent electrochemical signals, but also react with glutaraldehyde (GA) to immobilize different labeled antibodies. Using the modified nanospheres as immunoprobes, a sandwich-type immunosensor was fabricated to simultaneous detection of four tumor markers (CEA, CA199, CA125 and CA242) of pancreatic cancer. This designed immunosensor exhibited good linear relationships in range from 0.1 to 100ng mL(-1) for CEA, 1 to 150UmL(-1) for CA199, CA125 and CA242, corresponding detection limits 0.02ng mL(-1), 0.4UmL(-1), 0.3UmL(-1) and 0.4UmL(-1), respectively. Meanwhile, the immunosensor was applied in analysis of clinical serum samples, whose results were well agreed with the enzyme-linked immunosorbent assay (ELISA), indicating that the proposed immunosensor gave a hope for the identification and validation of specific early cancer.

  15. Synthesis of Nanoporous Iminodiacetic Acid Sorbents for Binding Transition Metals

    PubMed Central

    Busche, Brad; Wiacek, Robert; Davidson, Joseph; Koonsiripaiboon, View; Yantasee, Wassana; Addleman, R. Shane; Fryxell, Glen E.

    2009-01-01

    Iminodiacetic acid (IDAA) forms strong complexes with a wide variety of metal ions. Using self-assembled monolayers in mesoporous supports (SAMMS) to present the IDAA ligand potentially allows for multiple metal-ligand interactions to enhance the metal binding affinity relative to that of randomly oriented polymer-based supports. This manuscript describes the synthesis of a novel nanostructured sorbent material built using self-assembly of a IDAA ligand inside a nanoporous silica, and demonstrates its use for capturing transition metal cations, and anionic metal complexes, such as PdCl4−2. PMID:22068901

  16. NOVEL POLY-GLUTAMIC ACID FUNCTIONALIZED MICROFILTRATION MEMBRANES FOR SORPTION OF HEAVY METALS AT HIGH CAPACITY

    EPA Science Inventory

    Various sorbent/ion exchange materials have been reported in the literature for metal ion entrapment. We have developed a highly innovative and new approach to obtain high metal pick-up utilizing poly-amino acids (poly-L-glutamic acid, 14,000 MW) covalently attached to membrane p...

  17. 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.

  18. 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...

  19. Chitosan Hydrogel Structure Modulated by Metal Ions

    PubMed Central

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-01-01

    As one of the most important polysaccharide, chitosan (CS) has generated a great deal of interest for its desirable properties and wide applications. In the utilization of CS materials, hydrogel is a major and vital branch. CS has the ability to coordinate with many metal ions by a chelation mechanism. While most researchers focused on the applications of complexes between CS and metal ions, the complexes can also influence gelation process and structure of CS hydrogel. In the present work, such influence was studied with different metal ions, revealing two different kinds of mechanisms. Strong affinity between CS and metal ions leads to structural transition from orientation to multi-layers, while weak affinity leads to composite gel with in-situ formed inorganic particles. The study gave a better understanding of the gelation mechanism and provided strategies for the modulation of hydrogel morphology, which benefited the design of new CS-based materials with hierarchical structure and facilitated the utilization of polysaccharide resources. PMID:27777398

  20. Headgroup interactions and ion flotation efficiency in mixtures of a chelating surfactant, different foaming agents, and divalent metal ions.

    PubMed

    Svanedal, Ida; Boija, Susanne; Norgren, Magnus; Edlund, Håkan

    2014-06-10

    The correlation between interaction parameters and ion flotation efficiency in mixtures of chelating surfactant metal complexes and different foaming agents was investigated. We have recently shown that chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) forms strong coordination complexes with divalent metal ions, and this can be utilized in ion flotation. Interaction parameters for mixed micelles and mixed monolayer formation for Mg(2+) and Ni(2+) complexes with the chelating surfactant 4-C12-DTPA and different foaming agents were calculated by Rubingh's regular solution theory. Parameters for the calculations were extracted from surface tension measurements and NMR diffusometry. The effects of metal ion coordination on the interactions between 4-C12-DTPA and the foaming agents could be linked to a previously established difference in coordination chemistry between the examined metal ions. As can be expected from mixtures of amphoteric surfactants, the interactions were strongly pH-dependent. Strong correlation was found between interaction parameter β(σ) for mixed monolayer formation and the phase-transfer efficiency of Ni(2+) complexes with 4-C12-DTPA during flotation in a customized flotation cell. In a mixture of Cu(2+) and Zn(2+), the significant difference in conditional stability constants (log K) between the metal complexes was utilized to selectively recover the metal complex with the highest log K (Cu(2+)) by ion flotation. Flotation experiments in an excess concentration of metal ions confirmed the coordination of more than one metal ion to the headgroup of 4-C12-DTPA.

  1. Headgroup interactions and ion flotation efficiency in mixtures of a chelating surfactant, different foaming agents, and divalent metal ions.

    PubMed

    Svanedal, Ida; Boija, Susanne; Norgren, Magnus; Edlund, Håkan

    2014-06-10

    The correlation between interaction parameters and ion flotation efficiency in mixtures of chelating surfactant metal complexes and different foaming agents was investigated. We have recently shown that chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) forms strong coordination complexes with divalent metal ions, and this can be utilized in ion flotation. Interaction parameters for mixed micelles and mixed monolayer formation for Mg(2+) and Ni(2+) complexes with the chelating surfactant 4-C12-DTPA and different foaming agents were calculated by Rubingh's regular solution theory. Parameters for the calculations were extracted from surface tension measurements and NMR diffusometry. The effects of metal ion coordination on the interactions between 4-C12-DTPA and the foaming agents could be linked to a previously established difference in coordination chemistry between the examined metal ions. As can be expected from mixtures of amphoteric surfactants, the interactions were strongly pH-dependent. Strong correlation was found between interaction parameter β(σ) for mixed monolayer formation and the phase-transfer efficiency of Ni(2+) complexes with 4-C12-DTPA during flotation in a customized flotation cell. In a mixture of Cu(2+) and Zn(2+), the significant difference in conditional stability constants (log K) between the metal complexes was utilized to selectively recover the metal complex with the highest log K (Cu(2+)) by ion flotation. Flotation experiments in an excess concentration of metal ions confirmed the coordination of more than one metal ion to the headgroup of 4-C12-DTPA. PMID:24824327

  2. The electron-transfer based interaction between transition metal ions and photoluminescent graphene quantum dots (GQDs): a platform for metal ion sensing.

    PubMed

    Huang, Hongduan; Liao, Lei; Xu, Xiao; Zou, Mingjian; Liu, Feng; Li, Na

    2013-12-15

    The electron-transfer based quenching effect of commonly encountered transition metal ions on the photoluminescence of grapheme quantum dots (GQDs) was for the first time investigated, and was found to be associated with electron configuration of the individual metal ion. Ethylene diamine tetraacetic acid (EDTA), the metal ion chelator, can competitively interact with metal ions to recover the quenched photoluminescence of GQDs. Basically, metal ions with empty or completely filled d orbits could not quench the photoluminescence of GQDs, but this quenching effect was observed for the metal ions with partly filled d orbits. Based on the quenching-recovering strategy, a simple optical metal sensing platform was established by taking Ni(2+) as an example. Using the nickel ion-specific chelating reagent, dimethylglyoxime (DMG), to replace EDTA, a detection limit of 4.1 μM was obtained in standard solution. This proposed strategy does not need further functionalization of GQDs, facilitating the application for simple, fast and cost-effective screening of metal ions.

  3. Flame Atomic Absorption Spectrometric Determination of Trace Metal Ions in Environmental and Biological Samples After Preconcentration on a Newly Developed Amberlite XAD-16 Chelating Resin Containing p-Aminobenzene Sulfonic Acid.

    PubMed

    Islam, Aminul; Ahmad, Akil; Laskar, Mohammad Asaduddin

    2015-01-01

    Amberlite® XAD-16 was functionalized with p-aminobenzene sulfonic acid via an azo spacer in order to prepare a new chelating resin, which was then characterized by water regain value, hydrogen ion capacity, elemental analyses, and IR spectral and thermal studies. The maximum uptake of Cu(II), Ni(II), Zn(II), Co(II), Cr(III), Fe(III), and Pb(II) ions was observed in the pH range 4.0-6.0 with the corresponding half-loading times of 6.5, 7.0, 8.0, 9.0, 11.0, 8.5, and 16.5 min. The sorption data followed Langmuir isotherms and a pseudo-second-order model. Thermodynamic quantities, ΔH and ΔS, based on the variation of the distribution coefficient with temperature were also evaluated. High preconcentration factors of 60-100 up to a low preconcentration limit of 4.0-6.6 μg/L have been achieved for the metal ions. The validity of the method was checked by analyzing standard reference materials and recoveries of trace metals after spiking. The analytical applications of the method were explored by analyzing natural water, mango pulp, mint leaves, and fish. PMID:25857893

  4. Enterovirus 71 adsorption on metal ion-composite chitosan beads.

    PubMed

    Lin, Ya-Ching; Lin, Shu-Ting; Chen, Cheng-Yi; Wu, Sheng-Chi

    2012-01-01

    In this study, we developed composite chitosan beads combining various metal ions, including Ni(2+), Cu(2+), Zn(2+), and Fe(2+), for direct adsorption of enterovirus 71 (EV71). The metal-ion species had significant effects on the adsorption capacity of beads. Among these metal ion-composite chitosan beads, Ni(2+)-chitosan beads exhibited the best adsorption capacity of EV71. Using a concentration of 0.01-M Ni(2+) was found to best provide for bead formation and EV71 adsorption. The adsorption of EV71 for Ni(2+)-chitosan beads at neutral or alkaline pH was favored. Under a competitive condition with albumin proteins, Ni(2+)-chitosan beads exhibited significant capacity of EV71 adsorption in culture media. The adsorption of EV71 on the Ni(2+)-chitosan beads was attributed to the strong binding between Ni(2+) ions chelated to the surface amino acid of EV71 capsids and Ni(2+) ions chelated on the chitosan materials. Moreover, the adsorbed EV71 retained its antigenicity and infectivity after desorption. The Ni(2+)-chitosan beads exhibit a promising application to EV71 adsorption and removal.

  5. Ion exclusion chromatography of aromatic acids.

    PubMed

    Mansour, Fotouh R; Kirkpatrick, Christine L; Danielson, Neil D

    2013-08-01

    The determination of aromatic acids by ion exclusion chromatography is challenging due to peak tailing and the long retention time of hydrophobic solutes. This review discusses the retention mechanisms and the factors affecting retention, eluents and detection methods used in ion exclusion chromatography of aromatic acids such as mono-, di-, tri- and tetra-carboxylic acids, amino acids, sulfonates and phenol. In addition, the different approaches used to improve the chromatographic separation of these compounds are also discussed. These approaches include introducing an internal gradient of the ionic strength, using vacancy ion exclusion chromatography, employing a hydrophilic cation exchange resin or adding a modifier such as heptanol to the dilute sulfuric acid mobile phase. The applications of these methods in the analysis of aromatic acids are provided with a table summarizing the stationary phases, the mobile phases and the detection methods.

  6. Chelation Properties of Modified Humic Acids Toward Some Trivalent Lanthanide Ions

    SciTech Connect

    Yaghmour, Remah N.; Khalili, Fawwaz I.; Mubarak, Mohammad S.

    2007-05-09

    Three kinds of humic acids, Fluka (I), Fluka (II), and Ega-chemie (III) were modified through condensation with formaldehyde to afford polymers I, II, and III, respectively. The chelation behavior of these modified humic acids polymers towards the trivalent lanthanide metal-ions, La3+, Ce3+, Nd3+, Sm3+, and Gd3+ was studied by a batch equilibration technique at 25 deg. C as a function of contact time, pH, counter ion and counter ion concentration. The highest metal-ion uptake of the three polymers was achieved at pH 7.0 and by using perchlorate as a counter ion. Results of the study have revealed that polymer II has the highest metal-ion uptake capacity, and that the metal-ion uptake falls in the order: Gd3+ > Sm3+ > Nd3+ > La3+ {approx_equal} Ce3+.

  7. 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.

  8. Metal ions in the atmosphere of Neptune.

    PubMed

    Lyons, J R

    1995-02-01

    Microwave propagation experiments performed with Voyager 2 at Neptune revealed sharp layers of electrons in Neptune's lower ionosphere with densities of approximately 10(4) per cubic centimeter. These layers are reminiscent of the sporadic-E layers in the Earth's ionosphere, and when taken together with data from the other giant planets, these data confirm the importance of the magnetic field in layer formation. A photochemical model that incorporates species produced by meteoroid ablation predicts that singly ionized magnesium is the most likely metal to be found in the layers, although laboratory data on the kinetics of metallic atoms and ions in a reducing environment are lacking. The metal chemistry discussed here is directly relevant to the abundant metals observed at the impact site of the G fragment of comet Shoemaker Levy 9 on Jupiter.

  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. 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.

  11. Neutralization by metal ions of the toxicity of sodium selenide.

    PubMed

    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.

  12. 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.

  13. On the mechanism of divalent metal ion chelator induced activation of the 7S nerve growth factor esteropeptidase. Activation by 2,2',2''-terpyridine and by 8-hydroxyquinoline 5-sulfonic acid.

    PubMed

    Pattison, S E; Dunn, M F

    1976-08-24

    Our previous studies (Pattison, S. E., and Dunn, M. F. (1975), Biochemistry 14, 2733) have shown that the reaction of divalent metal ion chelators with the 140 000 mol wt mouse submaxillary nerve growth factor protein (7S NGF) activates the iota-subunit esteropeptidase activity ca. sevenfold. Ultraviolet-visible spectral studies with the chelator 2,2',2''-terpyridine (terpyridine) and fluorescence emission studies with 8-hydroxyquinoline-5-sulfonic acid (HQSA) in combination with both conventional and rapid-mixing stopped-flow kinetic techniques have been employed in the present study to investigate (a) the mechanism of the chelator-induced activation process, and (b) the identity of the divalent metal ion involved. The spectral studies confirm the presence of stoichiometrically significant amounts of tightly bound zinc ion in native 7S NGF (1-2 g-atoms of An2+/mol of 7S NGF). The kinetic studies show that the reaction of terpyridine with 7S NGF occurs via a two-step process involving first a rapid, apparent second-order step (k1 = 1 x 10(6) M-1 s-1) to form a 7S NGF-Zn2+-chelator monocomplex, then a slow step to form a bis(terpyridine)-Zn(II) complex and activated 7S NGF in an apparent first-order process (kobsd = 0.10 min-1). This rate is, within experimental error, identical with the apparent first-order rate constant for the chelator-induced activation process (monitored by the rate of change in the steady-state rate of hydrolysis of chromophoric substrate, alpha-N-benzoyl-D,L-arginine-p-nitroanilide). Kinetic studies of the reaction of HQSA with native 7S NGF show that, under the same conditions of concentration, the rate of formation of the tris(HQSA)-Zn(II) complex is identical with the rate of the HQSA-induced activation of the 7S NGF esteropeptidase. Thus, these studies unambiguously establish that zinc ion is the metal ion involved in the chelator-induced activation process, and that activation involves removal of zinc ion from native 7S NGF.

  14. 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.

  15. Ion Atmosphere Near Nucleic Acids

    NASA Astrophysics Data System (ADS)

    Mohanty, Udayan

    2015-03-01

    We will discuss all­atom structure based model that explicitly includes ionic effects, i.e., electrostatic interactions with explicit magnesium ions and implicit KCl that allow us to carry out explicit solvent molecular dynamics simulations of adenine riboswitch and SAM­I riboswitch. Our predictions for the excess ions around the riboswitch, and the magnesium­RNA interaction free energy will be compared with experimental data. We will provide upper and lower bounds for preferential interaction coefficient, a statistical mechanical quantity that is a measure of excess ion atmosphere around a polyelectrolyte. We will discuss the role of surface charge density of mobile ions from added salt in determining the counterion release entropy associated with chain collapse. Finally, the Poisson's ratio of oligomeric DNA will be determined. (Work done in collaboration with R. Hayes, J. Noel, P. Whitford, S. Hennelly, J. Onuchic, and K. Sanbonmatsu.) Work supported by fellowship from John Simon Guggenheim Memorial Foundation.

  16. Interplay of metal ions and urease

    PubMed Central

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

    2009-01-01

    Summary 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

  17. Effects of metal ion adduction on the gas-phase conformations of protein ions.

    PubMed

    Flick, Tawnya G; Merenbloom, Samuel I; Williams, Evan R

    2013-11-01

    Changes in protein ion conformation as a result of nonspecific adduction of metal ions to the protein during electrospray ionization (ESI) from aqueous solutions were investigated using traveling wave ion mobility spectrometry (TWIMS). For all proteins examined, protein cations (and in most cases anions) with nonspecific metal ion adducts are more compact than the fully protonated (or deprotonated) ions with the same charge state. Compaction of protein cations upon nonspecific metal ion binding is most significant for intermediate charge state ions, and there is a greater reduction in collisional cross section with increasing number of metal ion adducts and increasing ion valency, consistent with an electrostatic interaction between the ions and the protein. Protein cations with the greatest number of adducted metal ions are no more compact than the lowest protonated ions formed from aqueous solutions. These results show that smaller collisional cross sections for metal-attached protein ions are not a good indicator of a specific metal-protein interaction in solution because nonspecific metal ion adduction also results in smaller gaseous protein cation cross sections. In contrast, the collisional cross section of α-lactalbumin, which specifically binds one Ca(2+), is larger for the holo-form compared with the apo-form, in agreement with solution-phase measurements. Because compaction of protein cations occurs when metal ion adduction is nonspecific, elongation of a protein cation may be a more reliable indicator that a specific metal ion-protein interaction occurs in solution.

  18. Effects of Metal Ion Adduction on the Gas-Phase Conformations of Protein Ions

    PubMed Central

    Flick, Tawnya G.; Merenbloom, Samuel I.; Williams, Evan R.

    2013-01-01

    Changes in protein ion conformation as a result of nonspecific adduction of metal ions to the protein during electrospray ionization (ESI) from aqueous solutions were investigated using traveling wave ion mobility spectrometry (TWIMS). For all proteins examined, protein cations (and in most cases anions) with nonspecific metal ion adducts are more compact than the fully protonated (or deprotonated) ions with the same charge state. Compaction of protein cations upon nonspecific metal ion binding is most significant for intermediate charge state ions, and there is a greater reduction in collisional cross section with increasing number of metal ion adducts and increasing ion valency, consistent with an electrostatic interaction between the ions and the protein. Protein cations with the greatest number of adducted metal ions are no more compact than the lowest protonated ions formed from aqueous solutions. These results show that smaller collisional cross sections for metal-attached protein ions are not a good indicator of a specific metal-protein interaction in solution, because nonspecific metal ion adduction also results in smaller gaseous protein cation cross sections. In contrast, the collisional cross section of α-lactalbumin, which specifically binds one Ca2+, is larger for the holo-form compared to the apo-form, in agreement with solution-phase measurements. Because compaction of protein cations occurs when metal ion adduction is nonspecific, elongation of a protein cation may be a more reliable indicator that a specific metal ion-protein interaction occurs in solution. PMID:23733259

  19. 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.

  20. 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

  1. 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.

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

    PubMed

    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.

  3. 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.

  4. Retention of heavy metal ions on comb-type hydrogels based on acrylic acid and 4-vinylpyridine, synthesized by gamma radiation

    NASA Astrophysics Data System (ADS)

    González-Gómez, Roberto; Ortega, Alejandra; Lazo, Luz M.; Burillo, Guillermina

    2014-09-01

    Two novel comb-type hydrogels based on pH-sensitive monomers (acrylic acid (AAc) and 4-vinylpyridine (4VP) were synthesized by gamma radiation. The systems were as follows: a) comb-type hydrogels of an AAc network followed by grafting of 4VP ((net-PAAc)-g-4VP) and b) comb-type hydrogels of an AAc network grafted onto polypropylene (PP) followed by grafting of 4VP (net-(PP-g-AAc)-g-4VP). The equilibrium isotherms and kinetics were evaluated for copper and zinc ions in aqueous solutions. The Zn(II) retention obtained was 480 mg g-1 and 1086 mg g-1 for (net-PAAc)-g-4VP and net-(PP-g-AAc)-g-4VP, respectively. At concentrations as low as ppm, retention efficiencies of approximately 90% were achieved for Cu(II) on (net-PAAc)-g-4VP and for Zn(II) on net-(PP-g-AAc)-g-4VP. Desorption of the hydrogels was also studied, and the results indicated that they can be used repeatedly in aqueous solutions. For both systems, the adsorption of Cu(II) and Zn(II) obeyed the Freundlich model, indicating heterogeneous sorption, and the retention process occurred by chemisorption. The sorption process follows a pseudo-second-order model.

  5. 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.

  6. 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.

  7. BIORECOVERY OF METALS FROM ACID MINE DRAINAGE

    EPA Science Inventory

    Acid mine water is an acidic, metal-bearing wastewater generated by the oxidation of metallic sulfides by certain bacteria in both active and abandoned mining operations. The wastewaters contain substantial quantities of dissolved solids with the particular pollutants dependant u...

  8. 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.

  9. Interaction of adenylic acid with alkaline earth metal ions in the crystalline solid and aqueous solution. Evidence for the sugar C'2-endo/anti, C'3-endo/anti and C'4-exon/anti conformational changes.

    PubMed

    Tajmir-Riahi, H A

    1990-09-10

    The reaction of adenosine 5'-monophosphoric acid (H2-AMP) with the alkaline earth metal ions has been investigated in aqueous solution at neutral pH. The solid salts of Mg-AMP.5H2O, Ca-AMP.6H2O, Sr-AMP.7H2O and Ba-AMP.7H2O were isolated and characterized by Fourier transform infrared, 1H-NMR spectroscopy and X-ray powder diffraction measurements. Spectroscopic and other evidence showed that the Sr-AMP.7H2O and Ba-AMP.7H2O are isomorphous, whereas the Mg-AMP.5H2O and Ca-AMP.6H2O are not similar. The Mg2+ binding is through the N-7 (inner-sphere) and the phosphate group (outer-sphere via H2O), while the Ca2+ binds to the phosphate group (inner-sphere) and to the base N-7 site (outer-sphere through H2O). The Sr2+ and Ba2+ bind to H2O molecules, H-bonding to the N-7, N-1 and the phosphate group (outer-sphere). In aqueous solution, an equilibrium between the inner- and outer-sphere metal ion bindings can be established. The sugar moiety exhibited C'2-endo/anti conformation, in the free H2-AMP acid and the magnesium salt, C'3-endo/anti in the calcium salt and unusual C'4-exo/anti, in the strontium and barium salts.

  10. How do metal ions direct ribozyme folding?

    NASA Astrophysics Data System (ADS)

    Denesyuk, Natalia A.; Thirumalai, D.

    2015-10-01

    Ribozymes, which carry out phosphoryl-transfer reactions, often require Mg2+ ions for catalytic activity. The correct folding of the active site and ribozyme tertiary structure is also regulated by metal ions in a manner that is not fully understood. Here we employ coarse-grained molecular simulations to show that individual structural elements of the group I ribozyme from the bacterium Azoarcus form spontaneously in the unfolded ribozyme even at very low Mg2+ concentrations, and are transiently stabilized by the coordination of Mg2+ ions to specific nucleotides. However, competition for scarce Mg2+ and topological constraints that arise from chain connectivity prevent the complete folding of the ribozyme. A much higher Mg2+ concentration is required for complete folding of the ribozyme and stabilization of the active site. When Mg2+ is replaced by Ca2+ the ribozyme folds, but the active site remains unstable. Our results suggest that group I ribozymes utilize the same interactions with specific metal ligands for both structural stability and chemical activity.

  11. Ion beam studies of hydrogen in metals

    SciTech Connect

    Myers, S.M.; Wampler, W.R.; Besenbacher, F.; Robinson, S.L.; Moody, N.R.

    1984-01-01

    Methods based on ion implantation and nuclear reaction analysis were used to investigate the behavior of hydrogen isotopes in metals. The binding enthalpy of deuterium (D) at irradiation effects, He bubbles, D/sub 2/ bubbles, and metal-oxide interfaces was measured for Al, Fe, Ni, Cu, Pd, austenitic stainless steel, Inconel, and amorphous Fe/sub 40/Ni/sub 40/P/sub 14/B/sub 6/. The binding enthalpies determined for the pure metals are in excellent agreement with mechanistic calculations based on effective-medium theory and other information. Surface-limited release of D from Fe, stainless steel, and Inconel was measured as a function of temperature and the state of surface oxidation. The release rate was accurately proportional to the square of the D concentration in solution, permitting the results to be expressed in terms of a surface recombination coefficient. This quantity was up to four orders of magnitude greater for an ion-sputtered surface than for a surface with electropolish oxide. The diffusion coefficient and solid solubility of tritium in stainless steel were measured for the first time at the ice point, thereby extending downward by three orders of magnitude the diffusivities available from conventional permeation experiments. Deuterium concentration profiles resulting from electrochemical charging of Incoloy 903 were measured as a function of charging current, thereby providing a direct, systematic calibration of such charging in an austenitic material where conventional permeation measurements are precluded by the small hydrogen diffusion rate.

  12. 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.

  13. Immunologically active metallic ion-containing polysaccharides of Achyrocline satureioides.

    PubMed

    Puhlmann, J; Knaus, U; Tubaro, L; Schaefer, W; Wagner, H

    1992-08-01

    Two homogeneous, metallic ion-containing pectic polysaccharides with mean M(r)s of 7600 and 15,000 were isolated from dried aerial parts of Achyrocline satureioides by anion exchange column chromatography on DEAE-Sepharose CL-6B and gel filtration column chromatography on Fractogel TSK HW-50 (S). The structures, as determined by methylation analysis, carboxyl reduction, and partial acid hydrolysis, were shown to be rhamnogalacturonans. Both pectins show a pronounced anticomplementary effect in vitro. The larger carbohydrate AS 4 of higher M(r) exerts anti-inflammatory activity and a strong enhancement of phagocytosis in vivo.

  14. A united physicochemical description of the protonation and metal ion complexation equilibria of natural organic acids (humic and fulvic acids). 2. Influence of polyelectrolyte properties and functional group heterogeneity on the protonation equilibria of fulvic acid

    USGS Publications Warehouse

    Ephraim, J.; Alegret, S.; Mathuthu, A.; Bicking, M.; Malcolm, R.L.; Marinsky, J.A.

    1986-01-01

    Potentiometric studies of the neutralization of several fulvic acid sources with standard base in aqueous and nonaqueous media have been conducted. Analysis of the results with a recently developed unified physicochemical model has shown that the protonation behavior of these fulvic acid sources is a reflection of (1) their polyelectrolyte nature and (2) their heterogeneity. It has been possible to ascribe the polyelectrolyte properties observed to a rather inflexible fulvic acid molecule whose variably charged surface is impermeable to simple electrolyte. ?? 1986 American Chemical Society.

  15. Studies on stannic selenoarsenate. II. Separation of uranium from numerous metal ions

    SciTech Connect

    Nabi, S.A.; Siddiqi, Z.M.; Rao, R.A.K.

    1982-12-01

    Stannic selenoarsenate has been synthesized by adding 0.05 M sodium selenite and 0.05 M sodium arsenate to a 0.05 M solution of stannic chloride in a volume ratio of 1:1:1 at pH 1. A tentative structure has been proposed on the basis of chemical composition, pH titrations, and infrared and thermogravimetric analyses. Distribution coefficients of several metal ions have been studied in hydrochloric acid, citric acid, ammonium citrate-citric acid, and water-dioxane systems. The unusual adsorption behavior or uranium has been utilized for its quantitative separation from several metal ions.

  16. Metal-ion rescue revisited: biochemical detection of site-bound metal ions important for RNA folding.

    PubMed

    Frederiksen, John K; Li, Nan-Sheng; Das, Rhiju; Herschlag, Daniel; Piccirilli, Joseph A

    2012-06-01

    Within the three-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules to form chelates. These interactions help the RNA adopt and maintain specific conformations and frequently make essential contributions to function. Defining the locations of these site-bound metal ions remains challenging despite the growing database of RNA structures. Metal-ion rescue experiments have provided a powerful approach to identify and distinguish catalytic metal ions within RNA active sites, but the ability of such experiments to identify metal ions that contribute to tertiary structure acquisition and structural stability is less developed and has been challenged. Herein, we use the well-defined P4-P6 RNA domain of the Tetrahymena group I intron to reevaluate prior evidence against the discriminatory power of metal-ion rescue experiments and to advance thermodynamic descriptions necessary for interpreting these experiments. The approach successfully identifies ligands within the RNA that occupy the inner coordination sphere of divalent metal ions and distinguishes them from ligands that occupy the outer coordination sphere. Our results underscore the importance of obtaining complete folding isotherms and establishing and evaluating thermodynamic models in order to draw conclusions from metal-ion rescue experiments. These results establish metal-ion rescue as a rigorous tool for identifying and dissecting energetically important metal-ion interactions in RNAs that are noncatalytic but critical for RNA tertiary structure.

  17. Metal ion-inducing metabolite accumulation in Brassica rapa.

    PubMed

    Jahangir, Muhammad; Abdel-Farid, Ibrahim Bayoumi; Choi, Young Hae; Verpoorte, Robert

    2008-09-29

    Plants face a number of biotic and abiotic environmental stress factors during growth. Among the abiotic factors, in particular, a great deal of attention has been paid to metals not only because of their increasing amounts in the environment due to rapid industrial development but also because of the variation of metal composition in soil. Cultivation of crops close to industrial areas or irrigation with contaminated water may result in both growth inhibition and tissue accumulation of metals. Brassica species are well known as metal accumulators and are being used for phytoremediation of contaminated soils. However, the metal tolerance mechanism in the plant still remains unclear. In order to investigate the metabolomic changes induced by metal ions in Brassica, plants were subjected to concentrations 50, 100, 250 and 500 mmol of copper (Cu), iron (Fe) and manganese (Mn) in separate treatments. (1)H NMR and two-dimensional NMR spectra coupled with principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) were applied to investigate the metabolic change in Brassica rapa (var. Raapstelen). The (1)H-NMR analysis followed by the application of chemometric methods revealed a number of metabolic consequences. Among the metabolites that showed variation, glucosinolates and hydroxycinnamic acids conjugated with malates were found to be the discriminating metabolites as were primary metabolites like carbohydrates and amino acids. This study shows that the effects of Cu and Fe on plant metabolism were larger than those of Mn and that the metabolomic changes varied not only according to the type of metal but also according to its concentration.

  18. 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.

  19. 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.

  20. A set of alkali and alkaline-earth coordination polymers based on the ligand 2-(1H-benzotriazol-1-yl) acetic acid: Effects the radius of metal ions on structures and properties

    SciTech Connect

    Wang, Jin-Hua; Tang, Gui-Mei; Qin, Ting-Xiao; Yan, Shi-Chen; Wang, Yong-Tao; Cui, Yue-Zhi; Weng Ng, Seik

    2014-11-15

    Four new metal coordination complexes, namely, [Na(BTA)]{sub n} (1), [K{sub 2}(BTA){sub 2}(μ{sub 2}-H{sub 2}O)]{sub n} (2), and [M(BTA){sub 2}(H{sub 2}O){sub 2}]{sub n} (M=Ca(II) and Sr(II) for 3 and 4, respectively) [BTA=2-(1H-benzotriazol-1-yl) acetic anion], have been obtained under hydrothermal condition, by reacting the different alkali and alkaline-earth metal hydroxides with HBTA. Complexes 1–4 were structurally characterized by X-ray single-crystal diffraction, EA, IR, PXRD, and thermogravimetry analysis (TGA). These complexes display low-dimensional features displaying various two-dimensional (2D) and one-dimensional (1D) coordination motifs. Complex 1 displays a 2D layer with the thickness of 1.5 nm and possesses a topologic structure of a 11 nodal net with Schläfli symbol of (3{sup 18}). Complex 2 also shows a thick 2D sheet and its topologic structure is a 9 nodes with Schläfli symbol of (3{sup 11}×4{sup 2}). Complexes 3 and 4 possess a 1D linear chain and further stack via hydrogen bonding interactions to generate a three-dimensional supramolecular architecture. These results suggest that both the coordination preferences of the metal ions and the versatile nature of this flexible ligand play a critical role in the final structures. The luminescent spectra show strong emission intensities in complexes 1–4, which display violet photoluminescence. Additionally, ferroelectric, dielectric and nonlinear optic (NLO) second-harmonic generation (SHG) properties of 2 are discussed in detail. - Graphical abstract: A set of alkali and alkaline-earth metal coordination polymers were hydrothermally synthesized by 2-(1H-benzotriazol-1-yl)acetic acid, displaying interesting topologic motifs from two-dimension to one-dimension and specific physical properties. - Highlights: • Alkali and alkaline-earth metal coordination polymers have been obtained. • The ligand 2-(1H-benzotriazol-1-yl)acetic acid has been adopted. • The two-dimensional and one

  1. Adsorption of humic acids and trace metals in natural waters

    NASA Technical Reports Server (NTRS)

    Leung, W. H.

    1982-01-01

    Studies concerning the interactions between suspended hydrous iron oxide and dissolved humic acids and trace metals are reported. As a major component of dissolved organic matters and its readiness for adsorption at the solid/water interface, humic acids may play a very important role in the organometallic geochemistry of suspended sediments and in determining the fate and distribution of trace metals, pesticides and anions in natural water systems. Most of the solid phases in natural waters contain oxides and hydroxides. The most simple promising theory to describe the interactions of hydrous iron oxide interface is the surface complex formation model. In this model, the adsorptions of humic acids on hydrous iron oxide may be interpreted as complex formation of the organic bases (humic acid oxyanions) with surface Fe ions. Measurements on adsorptions were made in both fresh water and seawater. Attempts have been made to fit our data to Langmuir adsorption isotherm. Adsorption equilibrium constants were determined.

  2. Persistent Ion Pairing in Aqueous Hydrochloric Acid

    SciTech Connect

    Baer, Marcel D.; Fulton, John L.; Balasubramanian, Mahalingam; Schenter, Gregory K.; Mundy, Christopher J.

    2014-07-03

    For strong acids, like hydrochloric acid, the complete dissociation into an excess proton and conjugated base as well as the formation of independent solvated charged fragments is assumed. The existence of a chloride-Hyronium (Cl-H3O+) contact ion pairs even in moderate concentration hydrochloric acid (2.5 m) demonstrates that the counter ions do not behave merely as spectators. Through the use of modern extended X-ray absorption fine structure (EXAFS) measurements in conjunction with state-of-the-art density functional theory (DFT) simulations, we are able to obtain an unprecedented view into the molecular structure of medium to high concentrated electrolytes. Here we report that the Cl-H3O+ contact ion pair structure persists throughout the entire concentration range studied and that these structures differ significantly from moieties studied in micro-solvated hydrochloric acid clusters. Characterizing distinct populations of these ion pairs gives rise to a novel molecular level description of how to think about the activity of the proton that impacts our picture of the pH scale. Funding for CJM, GKS, and JLF was provided by DOE Office of Science, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences, and Biosciences. Funding for MDB was provided throught the Laboratory Directed Research and Development program at Pacific Northwest National Laboratory. MB was funded through Argonne National Laboratory.

  3. 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

  4. 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.

  5. Optical methods for the detection of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Uglov, A. N.; Bessmertnykh-Lemeune, A.; Guilard, R.; Averin, A. D.; Beletskaya, I. P.

    2014-03-01

    The review covers an important area of the modern chemistry, namely, the detection of heavy metal ions using optical molecular detectors. The role of this method in metal ion detection and the physicochemical grounds of operation of chemosensors are discussed, and examples of detection of most abundant heavy metal ions and synthetic approaches to molecular detectors are presented. The immobilization of molecular detectors on solid substrates for the design of analytical sensor devices is described. The bibliography includes 178 references.

  6. 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.

  7. 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.

  8. Study of the Interactions Between Transition Metal Ions and Peptides by CALIFORNIUM-252 Plasma Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hu, Zhaohong

    This dissertation focuses on the study of interactions between transition metal ions (Cu(II), Zn(II), Pd(II), Pt(II)) and peptides (bradykinins and angiotensins). Chapter I provides an overview on the fundamental issues related to and techniques used for studying transition metal ion -peptide/protein complexes. It also reviews different mass spectroscopic techniques used for metal ion-peptide studies. Chapter II delineates the principle of ^{252 }Cf-PDMS instrumentation and the sample preparation methods utilized for this dissertation research. In order to study metal ion-peptide complexes with PDMS, it is essential to define the relationship between complex structures identified from PD mass spectra and complexes formed in solution phase. Chapter III includes the studies of the effects of solution conditions on the detection of metal ion-peptide complexes in PDMS. Solution pH is the most important factor for determining the formation of a complex. Reaction time, reactant concentration, and reaction temperature all display distinct influences on PDMS results. It demonstrates that the PDMS results are closely correlated with the complexes pre-formed in aqueous solution. Chapter IV provides ample spectroscopic data on peptides and their metal ion complexes. The metal ion -containing molecular ions observed provide information on numbers of metal ion-binding sites in a peptide and metal ion-affinity of the peptide. By analyzing fragmentation patterns, amino acid residues and functional groups involved in metal ion binding in a peptide can be identified.

  9. 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.

  10. Calmodulin inhibition: a possible predictor of metal-ion toxicity

    SciTech Connect

    Williams, M.W.; Turner, J.E.; Hsie, A.W.

    1986-01-01

    A correlation between CE/sub 50/, the metal-ion concentration which reduces the cloning efficiency of CHO cells by 50%, and IC/sub 50/, the metal-ion concentration that produces an inhibition of calmodulin activity of 50%, is reported for 10 divalent metal ions. It is thus suggested that IC/sub 50/ might be used as a predictor of metal-ion toxicity in CHO cells. Arguments are presented to support the extrapolation of these results to other pollutants and to other biological species.

  11. Conformational thermodynamics of metal-ion binding to a protein

    NASA Astrophysics Data System (ADS)

    Das, Amit; Chakrabarti, J.; Ghosh, Mahua

    2013-08-01

    Conformational changes in proteins induced by metal-ions play extremely important role in various cellular processes and technological applications. Dihedral angles are suitable conformational variables to describe microscopic conformations of a biomacromolecule. Here, we use the histograms of the dihedral angles to study the thermodynamics of conformational changes of a protein upon metal-ion binding. Our method applied to Ca2+ ion binding to an important metalloprotein, Calmodulin, reveals different thermodynamic changes in different metal-binding sites. The ligands coordinating to Ca2+ ions also play different roles in stabilizing the metal-ion coordinated protein-structure. Metal-ion binding induce remarkable thermodynamic changes in distant part of the protein via modification of secondary structural elements.

  12. Calculated distortions induced by metal-ion binding to simple oligonucleotide systems: Implications for toxicity

    SciTech Connect

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

    1990-01-01

    We have previously published detailed results of calculations of the binding of the metal ions, Cd{sup 2+} and Ca{sup 2+}, to the dinucleoside monophosphate GpC in water. These ions, which have the same charge and radius, differ enormously in their toxicity to man and other biological systems. Our calculations showed contrasting behavior in the binding of these two metal ions to GpC. We suggest the hypothesis that structural distortions calculated for metal ions binding to simple nucleic-acid systems might serve as a indicator of an ion's potential ability to alter molecular activity and hence to be toxic to an organism. Furthermore, the degree of distortion might be correlated with the degree of toxicity as measured by some suitable criteria. The present paper reports the results of binding calculations for a number of other metal ions, of different valence states, with several dinucleoside monophosphates in water. A general trend of distortion with the type of binding of the metal ions is found. We are seeking quantitative measures of distortion to correlate with indicators of acute toxicity that we have measured for 24 metal ions using mice, Drosophila, and CHO cells. 3 refs., 3 figs.

  13. Outersphere and innersphere coordinated metal ions in an aminoacyl-tRNA synthetase ribozyme.

    PubMed

    Saito, Hirohide; Suga, Hiroaki

    2002-12-01

    Metal ions are essential cofactors for various ribozymes. Here we dissect the roles of metal ions in an aminoacyl-tRNA synthetase-like ribozyme (ARS ribozyme), which was evolved in vitro. This ribozyme can charge phenylalanine on tRNA in cis, where it is covalently attached to the 5'-end of tRNA (i.e. a form of precursor tRNA), as well as in trans, where it can act as a catalyst. The presence of magnesium ion is essential for this ribozyme to exhibit full catalytic activity. Metal-dependent kinetics, as well as structural mappings using Tb3+ in competition with Mg2+ or Co(NH3)6(3+), identified two potential metal-binding sites which are embedded near the tRNA-binding site. The high affinity metal-binding site can be filled with either Mg2+ or Co(NH3)6(3+) and thus the activity relies on a metal ion that is fully coordinated with water or ammonium ions. This site also overlaps with the amino acid-binding site, suggesting that the metal ion plays a role in constituting the catalytic core. The weak metal-binding site is occupied only by a metal ion(s) that can form innersphere contacts with ligands in the ribozyme and, hence, Mg2+ can enhance ribozyme activity, but Co(NH3)6(3+) cannot. The experiments described in this work establish the roles of metal ions that have distinct coordination properties in the ARS ribozyme.

  14. Whole blood metal ion measurement reproducibility between different laboratories.

    PubMed

    Rahmé, Michel; Lavigne, Martin; Barry, Janie; Cirtiu, Ciprian Mihai; Bélanger, Patrick; Vendittoli, Pascal-André

    2014-11-01

    Monitoring patients' metal ion blood concentrations can be useful in cases of problematic metal on metal hip implants. Our objective was to evaluate the reproducibility of metal ion level values measured by two different laboratories. Whole blood samples were collected in 46 patients with metal on metal hip arthroplasty. For each patients, two whole blood samples were collected and analyzed by two laboratories. Laboratory 1 had higher results than laboratory 2. There was a clinically significant absolute difference between the two laboratories, above the predetermined threshold, 35% of Cr samples and 38% of Co samples. All laboratories do not use the same technologies for their measurements. Therefore, decision to revise a metal on metal hip arthroplasty should rely on metal ion trends and have to be done in the same laboratory.

  15. 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.

  16. Evaluation of dry ashing in conjunction with ion chromatographic determination of transition metal ions in pig feed samples.

    PubMed

    Van paemel, Marleen R; De Rycke, Herman; Millet, Sam; Hesta, Myriam; Janssens, Geert P J

    2005-03-23

    The contents of transition metal ions iron, copper, zinc, and manganese were simultaneously determined in pig feed using an ion chromatographic technique (IC) preceded by dry ashing. Employing ion exchange, the ions were separated on an IonPac CS5A column used in combination with a pyridine-2,6-dicarboxylic acid based eluent. The separation was followed by spectrophotometric detection after postcolumn reaction with 4-(2-pyridylazo)resorcinol. Dry ashing parameters were varied to assess their role in potential analyte loss. Quantitative recoveries (>95%) were obtained for all analytes with a dry ashing method that included a moderate temperature-time regime and ash leaching support in the form of sonication and heat treatment. The use of HCl as leaching acid and the presence of alkaline earths in the matrix solution did not interfere with the chromatographic separation. PMID:15769106

  17. Biostable L-DNAzyme for Sensing of Metal Ions in Biological Systems.

    PubMed

    Cui, Liang; Peng, Ruizi; Fu, Ting; Zhang, Xiaobing; Wu, Cuichen; Chen, Huapei; Liang, Hao; Yang, Chaoyong James; Tan, Weihong

    2016-02-01

    DNAzymes, an important type of metal ion-dependent functional nucleic acid, are widely applied in bioanalysis and biomedicine. However, the use of DNAzymes in practical applications has been impeded by the intrinsic drawbacks of natural nucleic acids, such as interferences from nuclease digestion and protein binding, as well as undesired intermolecular interactions with other nucleic acids. On the basis of reciprocal chiral substrate specificity, the enantiomer of D-DNAzyme, L-DNAzyme, could initiate catalytic cleavage activity with the same achiral metal ion as a cofactor. Meanwhile, by using the advantage of nonbiological L-DNAzyme, which is not subject to the interferences of biological matrixes, as recognition units, a facile and stable L-DNAzyme sensor was proposed for sensing metal ions in complex biological samples and live cells.

  18. 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

  19. Spectroscopic investigations of lanthanide ion binding to nucleic acids.

    PubMed

    Morrow, Janet R; Andolina, Christopher M

    2012-01-01

    Luminescent lanthanide (Ln(III)) ions are valuable spectroscopic probes for metal ion binding sites in nucleic acids. In this chapter, we briefly review Ln(III) luminescence and the information available from these experiments. An emphasis is placed on direct excitation Eu(III) spectroscopy as a tool. Eu(III) excitation spectroscopy is used to show that solutions containing micromolar Eu(III), 100 mM NaCl, and 20 mM MES buffer contain predominantly a mononuclear Eu(III) aqua complex and an Eu(III) hydroxide complexes. The binding of these species to various RNA and DNA sequences are monitored by using Eu(III) excitation spectroscopy. Eu(III) luminescence lifetime data shows that the Eu(III) ion typically loses 1-3 water molecules to form innersphere complexes with RNA and DNA that contain tandem base pair mismatches or hairpin loops. In addition, early studies that used nucleobase-sensitized Eu(III) or Tb(III) luminescence within transfer RNA or in the hammerhead ribozyme are presented. Luminescence resonance energy transfer studies are shown to be useful for determining distances between bound Ln(III) ion and organic fluorophores or between two different Ln(III) ions. To supplement luminescence data, the binding sites of paramagnetic Ln(III) ions are determined by monitoring the chemical shifts of nucleotide protons. Binding sites are identified by following the protons that are influenced by the Ln(III) pseudo-contact shift.

  20. Effect of pH and metal ions on DPPH radical scavenging activity of tea.

    PubMed

    Pękal, Anna; Pyrzynska, Krystyna

    2015-02-01

    The 2,2'-diphenyl-1-picrylhydrazyl (DPPH) assay is commonly applied for the estimation of antioxidant activity of plant extracts. This article discusses the effect of a sample pH and the presence of metal ions on the results obtained using DPPH method for several tea infusions. Higher radical quenching was observed in less acidic media. The impact of metal ions depends of the types of metal ion and its concentration. Quercetin and epigallocatechin gallate were less efficient in the reaction with DPPH in the presence of Al(III). Desalting process using cation-exchange resin Dowex 50Wx8 decreased the content of metal ions in all studied tea infusions. The DPPH scavenging activity of the effluents after this process were higher than those of the primary extracts and this may be related to the actual antioxidant capacity of these samples.

  1. Inhibition studies of soybean (Glycine max) urease with heavy metals, sodium salts of mineral acids, boric acid, and boronic acids.

    PubMed

    Kumar, Sandeep; Kayastha, Arvind M

    2010-10-01

    Various inhibitors were tested for their inhibitory effects on soybean urease. The K(i) values for boric acid, 4-bromophenylboronic acid, butylboronic acid, and phenylboronic acid were 0.20 +/- 0.05 mM, 0.22 +/- 0.04 mM, 1.50 +/- 0.10 mM, and 2.00 +/- 0.11 mM, respectively. The inhibition was competitive type with boric acid and boronic acids. Heavy metal ions including Ag(+), Hg(2+), and Cu(2+) showed strong inhibition on soybean urease, with the silver ion being a potent inhibitor (IC(50) = 2.3 x 10(-8) mM). Time-dependent inhibition studies exhibited biphasic kinetics with all heavy metal ions. Furthermore, inhibition studies with sodium salts of mineral acids (NaF, NaCl, NaNO(3), and Na(2)SO(4)) showed that only F(-) inhibited soybean urease significantly (IC(50) = 2.9 mM). Competitive type of inhibition was observed for this anion with a K(i) value of 1.30 mM.

  2. Polyphosphazene membranes for metal ion separations

    SciTech Connect

    Stone, M.L.

    1996-05-01

    The Idaho National Engineering Laboratory (INEL), under sponsorship by the Bureau of Mines, evaluated the use of polyphosphazene-based polymer membranes for chemical separations. Synthetic membranes based on phosphazene inorganic polymers offer the promise of new industrial chemical separation technologies that are more energy efficient and economical than traditional phase change separation processes and extraction techniques. The research focused on the separation of metal ions from aqueous solutions. The polyphosphazene membranes were also tested for gaseous separations, results of which are presented in a separate Report of Investigation. Historically, membranes used for chemical separation have been prepared from organic polymers. In general, these membranes are stable only at temperatures less than 100{degrees}C, within narrow pH ranges, and in a very limited number of organic media. As a result, many organic- based membranes are unsuitable for industrial applications, which often involve harsh environments. In recent years, membrane research has focused on ceramic and metal membranes for use in the adverse environments of separation applications. These membranes are suitable for gas and liquid sieve separation applications, where molecules may be separated based on their molecular size. These membranes are not effective where additional selectivity is needed. A membrane that separates on the basis of solubility and that can perform separations in adverse environments is needed, and this need motivated the investigation of polyphosphazene membranes.

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

    PubMed Central

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

    2013-01-01

    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, resulting in similar electrochemical properties of these metal ions both in the peptide environment and in water. PMID:23283726

  4. Pore-functionalized polymer membranes for preconcentration of heavy metal ions.

    PubMed

    Vasudevan, T; Das, Sadananda; Sodaye, Suparna; Pandey, A K; Reddy, A V R

    2009-04-15

    Functionalized membranes containing carboxylate, phosphate and sulfonate groups were prepared by UV-initiator induced graft polymerization of the functional monomer (acrylic acid, ethylene glycol methacrylate phosphate (EGMP) and 2-acrylamido-2-methyl-1-propane sulfonic acid) with a crosslinker (methylenebisacrylamide) in the pores of poly(propylene) host membranes. The functionalized membranes thus obtained were characterized by gravimetry, FTIR spectroscopy, radiotracers and scanning electron microscopy for the degree of grafting and water uptake, presence of functional groups, ion-exchange capacity, and physical structure of the membranes, respectively. The uptakes of Cs(+), Ag(+), Sr(2+), Cd(2+), Hg(2+), Zn(2+), Eu(3+), Am(3+), Hf(4+) and Pu(4+) ions in the functionalized membranes were studied as a function of acidity of the equilibrating aqueous solution. Among the functionalized membranes prepared in the present work, the EGMP-grafted membrane (with phosphate groups) showed acid concentration dependent selectivity towards multivalent metal ions like Eu(3+), Am(3+), Hf(4+) and Pu(4+). The solvent extraction studies of EGMP monomer in methyl isobutyl ketone (MIBK) solvent indicated that divalent and trivalent metal ions form complexes with EGMP in 1:2 proportion, but the distribution coefficients of trivalent metal ions were significantly higher that for the divalent ions. The uptakes of Eu(3+) ions in monomeric EGMP (dissolved in MIBK) and polymeric EGMP (in the forms of crosslinked gel and membrane) were studied as a function of concentration of H(+) ions in the equilibrating solution. This study indicated that polymeric EGMP has better binding ability towards Eu(3+) as compared to monomeric EGMP. The variation of distribution coefficients of Eu(3+)/Am(3+) in gel and membrane as a function of H(+) ion concentration in the equilibrating aqueous solution indicated that ionic species held in the membrane and gel were not same. These results indicated that

  5. Slow collisions of multicharged ions with metal surfaces

    SciTech Connect

    Meyer, F.W.

    1993-12-31

    Some recent experimental results in the area of multicharged ion-surface interactions are summarized. Discussed are measurements of projectile K-Auger electron emission during interactions of hydrogen-like multicharged ions with clean and cesiated metal surfaces, measurements of total electron yields for various multicharged ions incident on metal targets, and measurements of projectile angular scattering during grazing metal surface collisions. The various experimental results are presented to illustrate progress in the understanding of multicharged ion-surface interactions in the area of above- vs sub-surface neutralization and relaxation processes, as well as to identify certain aspects of such interactions where the picture is as yet still incomplete.

  6. Dissecting the Metal Selectivity of MerR Monovalent Metal Ion Sensors in Salmonella

    PubMed Central

    Ibáñez, María M.; Cerminati, Sebastián; Checa, Susana K.

    2013-01-01

    Two homologous transcription factors, CueR and GolS, that belong to the MerR metalloregulatory family are responsible for Salmonella Cu and Au sensing and resistance, respectively. They share similarities not only in their sequences, but also in their target transcription binding sites. While CueR responds similarly to Au, Ag, or Cu to induce the expression of its target genes, GolS shows higher activation by Au than by Ag or Cu. We showed that the ability of GolS to distinguish Au from Cu resides in the metal-binding loop motif. Here, we identify the amino acids within the motif that determine in vivo metal selectivity. We show that residues at positions 113 and 118 within the metal-binding loop are the main contributors to metal selectivity. The presence of a Pro residue at position 113 favors the detection of Cu, while the presence of Pro at position 118 disfavors it. Our results highlight the molecular bases that allow these regulators to coordinate the correct metal ion directing the response to a particular metal injury. PMID:23645605

  7. Effect of microsolvation on hydrogen trapping potential of metal ions

    NASA Astrophysics Data System (ADS)

    Das, Ranjita; Bandaru, Sateesh; D'mello, Viola Caroline; Chattaraj, Pratim Kumar

    2013-03-01

    A thorough analysis is carried out to understand how the microsolvation affects the hydrogen adsorbing capacity of metal ions in the presence as well as absence of the counter ions. Calculations are done at different levels of theory by using different functionals and basis sets and also by using the BSSE correction. The Be2+ ion doped systems exhibit stronger interaction with the hydrogen molecule than the other metal doped systems. The extent of interaction is less affected by the method of computation. The reaction free energy values imply that adsorption on alkaline earth metal doped systems is spontaneous at room temperature. Interaction energies are favorable for hydrogen adsorption on the systems containing alkaline earth metal ions and the gravimetric density of adsorbed hydrogen molecule is more in those containing the alkali metal ions.

  8. 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

  9. DNA as sensors and imaging agents for metal ions.

    PubMed

    Xiang, Yu; Lu, Yi

    2014-02-17

    Increasing interest in detecting metal ions in many chemical and biomedical fields has created demands for developing sensors and imaging agents for metal ions with high sensitivity and selectivity. This review covers recent progress in DNA-based sensors and imaging agents for metal ions. Through both combinatorial selection and rational design, a number of metal-ion-dependent DNAzymes and metal-ion-binding DNA structures that can selectively recognize specific metal ions have been obtained. By attachment of these DNA molecules with signal reporters such as fluorophores, chromophores, electrochemical tags, and Raman tags, a number of DNA-based sensors for both diamagnetic and paramagnetic metal ions have been developed for fluorescent, colorimetric, electrochemical, and surface Raman detection. These sensors are highly sensitive (with a detection limit down to 11 ppt) and selective (with selectivity up to millions-fold) toward specific metal ions. In addition, through further development to simplify the operation, such as the use of "dipstick tests", portable fluorometers, computer-readable disks, and widely available glucose meters, these sensors have been applied for on-site and real-time environmental monitoring and point-of-care medical diagnostics. The use of these sensors for in situ cellular imaging has also been reported. The generality of the combinatorial selection to obtain DNAzymes for almost any metal ion in any oxidation state and the ease of modification of the DNA with different signal reporters make DNA an emerging and promising class of molecules for metal-ion sensing and imaging in many fields of applications.

  10. 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.

  11. Ferritin. Binding of beryllium and other divalent metal ions.

    PubMed

    Price, D J; Joshi, J G

    1983-09-25

    Rat liver homogenates in 0.1 M Tris, pH 7.5, were heated to 80 degrees C, cooled immediately, and centrifuged at 24,000 X g, and 7Be2+ was added to the supernatant. Twenty-five per cent of the radioactivity was bound to a single protein. It was purified to homogeneity and identified to be ferritin as judged by different criteria. These were sucrose density gradient centrifugation, electrophoresis in polyacrylamide gel of the native or sodium dodecyl sulfate-treated protein, reactivity to antibodies, isoelectric focusing, and total amino acid composition. Comparative study of the ability of ferritin or apoferritin to bind Cd2+, Zn2+, Cu2+, and Be2+ was conducted by using a gel equilibrium technique, Centifree micropartition technique, and microcentrifuge desalting technique. Ferritin could be saturated with Cd2+ or Zn2+ or Cu2+ but not with Be2+ even after 800 g atoms of Be2+ were bound. None of the bound Be2+ was dialyzable at 4 degrees C in 0.05 Tris acetate buffer, pH 8.5, but at pH 6.5 over 80% of the bound metal ion was dialyzed after 72 h. By contrast, apoferritin bound similar amounts of all four metal ions, some of which were dialyzable. By spectrophotometric titrations at pH 6.5 of Be2+ with sulfosalicylic acid (SSA), BeKDSSA was calculated to be 5.0 X 10(-6) M and by competition of sulfosalicyclic acid and ferritin for Be2+ the BeKDferritin was calculated to be 6.8 X 10(-6) M. PMID:6411722

  12. 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

  13. 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.

  14. Removal of heavy metals and lanthanides from industrial phosphoric acid process liquors

    SciTech Connect

    Koopman, C.; Witkamp, G.J.; Van Rosmalen, G.M.

    1999-11-01

    To diminish the discharge of heavy metals and lanthanides by the phosphoric acid industry, these impurities have to be removed from the mother liquor before their incorporation in the gypsum crystals. This can best be achieved by means of solvent extraction or ion exchange during the recrystallization of hemihydrate to dihydrate gypsum. Various commercial carriers and two ion-exchange resins were screened for their efficiency and selectivity. Light and heavy lanthanide ions are extracted from the recrystallization acid by didodecylnaphthalenesulfonic acid (Nacure 1052) and di(2-ethylhexyl)phosphoric acid (D2EHPA), and the heavy-metal ions by bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) and by bis(2,4,4-trimethylpentyl)monothiophosphinic acid (Cyanex 302). Mercury is also extracted by the anion carriers tri(C{sub 8}-C{sub 10})amine (Alamine 336) and tri(C{sub 8}-C{sub 10}) monomethyl ammonium chloride (Aliquat 336). Both Dowex C-500 and Amberlite IR-120 extract lanthanide and heavy-metal ions. Unfortunately, D2EHPA, Nacure 1052, and the two ion-exchange resins also show affinity for ions present in much higher concentrations, like calcium or iron ions.

  15. 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

  16. A critical overview of definitions and determination techniques of the internal resistance using lithium-ion, lead-acid, nickel metal-hydride batteries and electrochemical double-layer capacitors as examples

    NASA Astrophysics Data System (ADS)

    Piłatowicz, Grzegorz; Marongiu, Andrea; Drillkens, Julia; Sinhuber, Philipp; Sauer, Dirk Uwe

    2015-11-01

    The internal resistance (Ri) is one of the key parameters that determine the current state of electrochemical storage systems (ESS). It is crucial for estimating cranking capability in conventional cars, available power in modern hybrid and electric vehicles and for determining commonly used factors such as state-of-health (SoH) and state-of-function (SoF). However, ESS are complex and non-linear systems. Their Ri depends on many parameters such as current rate, temperature, SoH and state-of-charge (SoC). It is also a fact that no standardized methodologies exist and many different definitions and ways of Ri determination are being used. Nevertheless, in many cases authors are not aware of the consequences that occur when different Ri definitions are being used, such as possible misinterpretations, doubtful comparisons and false figures of merit. This paper focuses on an application-oriented separation between various Ri definitions and highlights the differences between them. The investigation was based on the following technologies: lead-acid, lithium-ion and nickel metal-hydride batteries as well as electrochemical double-layer capacitors. It is not the target of this paper to provide a standardized definition of Ri but to give researchers, engineers and manufacturers a possibility to understand what the term Ri means in their own work.

  17. Anion-exchange separations of metal ions in thiocyanate media.

    PubMed

    Fritz, J S; Kaminski, E E

    1971-05-01

    The analytical potential of a weak-base macroreticular anion-exchange resin for the quantitative separation of metal ions in thiocyanate media is investigated and demonstrated. Distribution data are given for the sorption of some 25 metal ions from aqueous mixtures of potassium thiocyanate (1.0M or less) and 0.5M hydrochloric acid. The magnitude of the distribution data suggests many possible separations, some of which were quantitatively performed by procedures which are fast, simple and require only mild conditions. Representative separations are removal of traces of iron(III) and copper(II) from water samples prior to the determination of water hardness (calcium and magnesium), separation of nickel(II) from vanadium(IV) and the separation of thorium(IV) from titanium(IV). Some multicomponent separations are the separation of rare earths(III) and thorium(IV) from scandium(III) and the separation of rare earths(III) from iron(III) and uranium(VI). PMID:18960914

  18. Transition metal cation separations with a resorcinarene-based amino acid stationary phase.

    PubMed

    Li, Na; Allen, Lee J; Harrison, Roger G; Lamb, John D

    2013-03-01

    A resorcinarene-based macrocyclic ligand functionalized with alanine and undecyl groups (AUA) was synthesized and applied to ion chromatographic separations. The selectivity and separation of transition metal ions on a column packed with AUA adsorbed onto 55% cross-linked styrene-divinylbenzene resin are presented. The upper and lower rims of the resorcinarene were modified with amino acids and -C(11)H(23) alkyl chains, respectively. The four carboxylic acid groups on the upper rim act as cation-exchangers while the four -C(11)H(23) alkyl chains serve to anchor the ligand to the resin surface by the hydrophobic effect. A systematic study of the effect of different eluent components including non-metal-chelating (HNO(3)) and chelating acids (oxalic acid, succinic acid, dipicolinic acid, and citric acid) on the retention of transition metal ions was investigated. Six metal ions (Mn(2+), Co(2+), Ni(2+), Cd(2+), Cu(2+), and Zn(2+)) were separated on the AUA column within a reasonable time with a single eluent gradient using oxalic acid. The separation is compared to that obtained using a commercial column containing carboxylic acid functional groups. The AUA column containing four preorganized carboxylic acid groups showed selectivity for Cu(2+) when no chelating eluent was present, a selectivity which was not observed with the comparison column.

  19. Coordination polymers with the chiral ligand N-p-tolylsulfonyl-L-glutamic acid: Influence of metal ions and different bipyridine ligands on structural chirality

    SciTech Connect

    He Rong; Song Huihua; Wei Zhen; Zhang Jianjun; Gao Yuanzhe

    2010-09-15

    Four new polymers, namely [Ni(-tsgluO)(2,4'-bipy){sub 2}(H{sub 2}O){sub 2}]{sub n}.5nH{sub 2}O (1), [Co(-tsgluO)(2,4'-bipy){sub 2}(H{sub 2}O){sub 2}]{sub n}.5nH{sub 2}O (2), [Ni(-tsgluO)(4,4'-bipy)]{sub n}.0.5nH{sub 2}O (3), and [Co(-tsgluO)(4,4'-bipy)]{sub n}.0.5nH{sub 2}O (4), where tsgluO{sup 2-}=(+)-N-p-tolylsulfonyl-L-glutamate dianion, 2,4'-bipy=2,4'-bipyridine, and 4,4'-bipy=4,4'-bipyridine, have been prepared and structurally characterized. Compounds 1 and 2 are isostructural and mononuclear, and crystallize in the acentric monoclinic space group Cc, forming 1D chain structures. Compound 3 is also mononuclear, but crystallizes in the chiral space group P2{sub 1}, forming a homochiral 2D architecture. In contrast to the other complexes, compound 4 crystallizes in the space group P-1 and is composed of binuclear [Co{sub 2}O{sub 6}N{sub 2}]{sub n}{sup 4-} units, which give rise to a 2D bilayer framework. Moreover, compounds 1, 2, and 4 self-assemble to form 3D supramolecular structures through {pi}-{pi} stacking and hydrogen-bonding interactions, while compound 3 is further hydrogen-bonded to form 3D frameworks. We have demonstrated the influence of the central metal and bipyridine ligands on the framework chirality of the coordination complexes. - Graphical abstract: Four novel polymers based on a chiral ligand were prepared and structurally characterized; it represents the first series of investigations about the effect of central metals and bipyridine ligands on framework chirality.

  20. Breast milk metal ion levels in a young and active patient with a metal-on-metal hip prosthesis.

    PubMed

    Nelis, Raymond; de Waal Malefijt, Jan; Gosens, Taco

    2013-01-01

    Metal-on-metal resurfacing arthroplasty of the hip has been used increasingly over the last 10 years in younger active patients. The dissolution of the metal wear particles results in measurable increases in cobalt and chromium ions in the serum and urine of patients with a metal-on-metal bearing. We measured the cobalt, chromium, and molybdenum ion levels in urine; serum; and breast milk in a young and active patient with a metal-on-metal hip prosthesis after a pathologic fracture of the femoral neck. Metal-on-metal hip prosthesis leads to increasing levels of molybdenum in breast milk in the short-term follow-up. There are no increasing levels of chromium and cobalt ions in breast milk. Besides the already known elevated concentrations in serum of chromium and cobalt after implantation of a metal-on-metal hip prosthesis, we found no increasing levels of chromium and cobalt in urine. PMID:22868068

  1. 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

  2. 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.

  3. A cross-reactive sensor array for the fluorescence qualitative analysis of heavy metal ions.

    PubMed

    Kang, Huaizhi; Lin, Liping; Rong, Mingcong; Chen, Xi

    2014-11-01

    A cross-reactive sensor array using mercaptopropionic acid modified cadmium telluride (CdTe), glutathione modified CdTe, poly(methacrylic acid) modified silver nanoclusters, bovine serum albumin modified gold nanoclusters, rhodamine derivative and calcein blue as fluorescent indicators has been designed for the detection of seven heavy metal ions (Ag(+), Hg(2+), Pb(2+), Cu(2+), Cr(3+), Mn(2+) and Cd(2+)). The discriminatory capacity of the sensor array to different heavy metal ions in different pH solutions has been tested and the results have been analyzed with linear discriminant analysis. Results showed that the sensor array could be used to qualitatively analyze the selected heavy metal ions. The array performance was also evaluated in the identification of known and unknown samples and the preliminary results suggested the promising practicability of the designed sensor assay.

  4. TIM-4 structures identify a Metal Ion-dependent Ligand Binding Site where phosphatidylserine binds

    PubMed Central

    Santiago, Cesar; Ballesteros, Angela; Martinez-Muñoz, Laura; Mellado, Mario; Kaplan, Gerardo G.; Freeman, Gordon J.; Casasnovas, José M.

    2008-01-01

    The T-cell immunoglobulin and mucin domain (TIM) proteins are important regulators of T cell responses. They have been linked to autoimmunity and cancer. Structures of the murine TIM-4 identified a Metal Ion-dependent Ligand Binding Site (MILIBS) in the immunoglobulin (Ig) domain of the TIM family. The characteristic CC’ loop of the TIM domain and the hydrophobic FG loop shaped a narrow cavity where acidic compounds penetrate and coordinate to a metal ion bound to conserved residues in the TIM proteins. The structure of phosphatidylserine bound to the Ig domain showed that the hydrophilic head penetrates into the MILIBS and coordinates with the metal ion, while the aromatic residues on the tip of the FG loop interacted with the fatty acid chains and could insert into the lipid bilayer. Our results also revealed a significant role of the MILIBS in trafficking of TIM-1 to the cell surface. PMID:18083575

  5. 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.

  6. 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.

  7. Metal ion sensing solution containing double crossover DNA

    NASA Astrophysics Data System (ADS)

    Park, Byeongho; Dugasani, Sreekantha R.; Cho, Youngho; Oh, Juyeong; Kim, Chulki; Seo, Min Ah; Lee, Taikjin; Jhon, Young Miin; Woo, Deok Ha; Lee, Seok; Jun, Seong Chan; Park, Sung Ha; Kim, Jae Hun

    2015-07-01

    The current study describes metal ion sensing with double crossover DNAs (DX1 and DX2), artificially designed as a platform of doping. The sample for sensing is prepared by a facile annealing method to grow the DXs lattice on a silicon/silicon oxide. Adding and incubating metal ion solution with the sensor substrate into the micro-tube lead the optical property change. Photoluminescence (PL) is employed for detecting the concentration of metal ion in the specimen. We investigated PL emission for sensor application with the divalent copper. In the range from 400 to 650 nm, the PL features of samples provide significantly different peak positions with excitation and emission detection. Metal ions contribute to modify the optical characteristics of DX with structural and functional change, which results from the intercalation of them into hydrogen bonding positioned at the center of double helix. The PL intensity is decreased gradually after doping copper ion in the DX tile on the substrate.

  8. Adhesive bonding of ion beam textured metals and fluoropolymers

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Sovey, J. S.

    1978-01-01

    An electron bombardment argon ion source was used to ion etch various metals and fluoropolymers. The metal and fluoropolymers were exposed to (0.5 to 1.0) keV Ar ions at ion current densities of (0.2 to 1.5) mA/sq cm for various exposure times. The resulting surface texture is in the form of needles or spires whose vertical dimensions may range from tenths to hundreds of micrometers, depending on the selection of beam energy, ion current density, and etch time. The bonding of textured surfaces is accomplished by ion beam texturing mating pieces of either metals or fluoropolymers and applying a bonding agent which wets in and around the microscopic cone-like structures. After bonding, both tensile and shear strength measurements were made on the samples. Also tested, for comparison's sake, were untextured and chemically etched fluoropolymers. The results of these measurements are presented.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Metal etching with reactive gas cluster ion beams using pickup cell

    SciTech Connect

    Toyoda, Noriaki; Yamada, Isao

    2012-11-06

    Mixed gas cluster ion beams were formed using pickup cell for metal etching. O{sub 2} neutral clusters pick up acetic acid and formed mixed cluster beam. By using O{sub 2}-GCIB with acetic acid, enhancement of Cu etching was observed. Because of dense energy deposition by GCIB, etching of Cu proceeds by CuO formation, enhancement of chemical reaction with acetic acid and desorption of etching products. Surface roughening was not observed on poly crystalline Cu because of the small dependence of etching rate on crystal orientation. Halogen free and low-temperature metal etching with GCIB using pickup cell is possible.

  15. Metal etching with reactive gas cluster ion beams using pickup cell

    NASA Astrophysics Data System (ADS)

    Toyoda, Noriaki; Yamada, Isao

    2012-11-01

    Mixed gas cluster ion beams were formed using pickup cell for metal etching. O2 neutral clusters pick up acetic acid and formed mixed cluster beam. By using O2-GCIB with acetic acid, enhancement of Cu etching was observed. Because of dense energy deposition by GCIB, etching of Cu proceeds by CuO formation, enhancement of chemical reaction with acetic acid and desorption of etching products. Surface roughening was not observed on poly crystalline Cu because of the small dependence of etching rate on crystal orientation. Halogen free and low-temperature metal etching with GCIB using pickup cell is possible.

  16. Metal-ion dependent catalytic properties of Sulfolobus solfataricus class ii α-mannosidase.

    PubMed

    Nielsen, Jonas Willum; Poulsen, Nina Rødtness; Johnsson, Anna; Winther, Jakob Rahr; Stipp, S L S; Willemoës, Martin

    2012-10-01

    The active site for the family GH38 class II α-mannosidase is constituted in part by a divalent metal ion, mostly Zn(2+), as revealed in the crystal structures of enzymes from both animal and bacterial sources. The metal ion coordinates to the bound substrate and side chains of conserved amino acid residues. Recently, evidence has accumulated that class II α-mannosidase is active in complex with a range of divalent metal ions. In the present work, with employment of the class II α-mannosidase, ManA, from the hyperthermophilic archaeon Sulfolobus solfataricus, we explored the influence of the divalent metal ion on the associated steady-state kinetic parameters, K(M) and k(cat), for various substrates. With p-nitrophenyl-α-d-mannoside as a substrate, the enzyme showed activity in the presence of Co(2+), Cd(2+), Mn(2+), and Zn(2+), whereas Ni(2+) and Cu(2+) were inhibitory and nonactivating. Co(2+) was the preferred metal ion, with a k(cat)/K(M) value of about 120 mM(-1) s(-1), 6 times higher than that with Cd(2+) and Zn(2+) and 10 times higher than that with Mn(2+). With α-1,2-, α-1,3-, α-1,4-, or α-1,6-mannobiose as a substrate, Co(2+) was the only metal ion promoting hydrolysis of all substrates; however, Mn(2+), Cd(2+), and Zn(2+) could substitute to a varying extent. A change in the divalent metal ion generally affected the K(M) for the hydrolysis of p-nitrophenyl-α-d-mannoside; however, changes in both k(cat) and K(M) for the hydrolysis of α-mannobioses were observed, along with changing preferences for the glycosidic linkage. Finally, it was found that the metal ion and substrate bind in that order via a steady-state, ordered, sequential mechanism.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. Anion Effects on Sodium Ion and Acid Molecule Adduction to Protein Ions in Electrospray Ionization Mass Spectrometry

    PubMed Central

    Flick, Tawnya G.; Merenbloom, Samuel I.; Williams, Evan R.

    2012-01-01

    Gaseous protein–metal ion and protein–molecule complexes can be readily formed by electrospray ionization (ESI) from aqueous solutions containing proteins and millimolar concentrations of sodium salts of various anions. The extent of sodium and acid molecule adduction to multiply charged protein ions is inversely related and depends strongly on the proton affinity (PA) of the anion, with extensive sodium adduction occurring for anions with PA values greater than ~300 kcal·mol−1 and extensive acid molecule adduction occurring for anions with PA values less than 315 kcal·mol−1. The role of the anion on the extent of sodium and acid molecule adduction does not directly follow the Hofmeister series, suggesting that direct protein–ion interactions may not play a significant role in the observed effect of anions on protein structure in solution. These results indicate that salts with anions that have low PA values may be useful solution-phase additives to minimize nonspecific metal ion adduction in ESI experiments designed to identify specific protein-metal ion interactions. PMID:21952761

  4. Formation and photodetachment of cold metal cluster negative ions

    NASA Astrophysics Data System (ADS)

    Zheng, L.-S.; Brucat, P. J.; Pettiette, C. L.; Yang, S.; Smalley, R. E.

    1985-10-01

    A general method is described for the formation of cold metal cluser negative ion beams which serve as excellent sources for photodetachment experiments. The method involves the pulsed laser vaporization of a metal target at the throat of a pulsed supersonic helium expansion. By the optimization of source conditions, intense beams (greater than 105 ions/pulse) of both positive and negative ions are produced routinely. Ionization of the metal cluster molecules, either during vaporization or by irradiation with 193 nm light, occurs prior to supersonic expansion and produces a cold plasma entrained in the neural flow that is renitent to stray electric and magnetic fields, unlike photoions produced in the collisionless downstream molecular beam. The enhancement of the negative ion flux by 193 nm irradiation is believed to be evidence for efficient electron attachment of low energy photoelectrons generated in the nozzle region. This attachment process, however, is apparently not effective for molecules containing less than ˜4 metal atoms. Laser irradition of mass-selected cluster anions extracted from these cold ion beams reveal that photodetachment of the metal cluster negative ion is always the preferred pathway, even when fragmentation of the ion is possible. This new negative ion production technique should therefore permit measurement of both electron affinities and photoelectron spectra as a function of cluster size and composition.

  5. Metal ion acquisition in Staphylococcus aureus: overcoming nutritional immunity

    PubMed Central

    Cassat, James E.

    2013-01-01

    Transition metals are essential nutrients to virtually all forms of life, including bacterial pathogens. In Staphylococcus aureus, metal ions participate in diverse biochemical processes such as metabolism, DNA synthesis, regulation of virulence factors, and defense against oxidative stress. As an innate immune response to bacterial infection, vertebrate hosts sequester transition metals in a process that has been termed “nutritional immunity.” To successfully infect vertebrates, S. aureus must overcome host sequestration of these critical nutrients. The objective of this review is to outline the current knowledge of staphylococcal metal ion acquisition systems, as well as to define the host mechanisms of nutritional immunity during staphylococcal infection. PMID:22048835

  6. Uranyl photoprobing of a four-way DNA junction: evidence for specific metal ion binding.

    PubMed Central

    Møllegaard, N E; Murchie, A I; Lilley, D M; Nielsen, P E

    1994-01-01

    Metal ions are very important in mediating the folding of nucleic acids, as exemplified by the folding of the four-way DNA junction into the stacked X-conformation. Uranyl ion-mediated photocleavage provides a method for the localization of high-affinity ion binding sites in nucleic acids, and we have applied this to the four-way DNA junction. We have made the following observations. (i) Uranyl ions (UO2(2+)) suppressed the reactivity of junction thymine bases against attack by osmium tetroxide, indicating that the uranyl ion induces folding of the junction into a stacked conformation. (ii) DNA located immediately at the point of strand exchange on the two exchanging strands was hypersensitive to uranyl photocleavage. The relative hypersensitivity was considerably accentuated when the photocleavage was carried out in the presence of citrate ions. This suggests the presence of a tight binding site for the uranyl ion in the junction. (iii) The same positions were significantly protected from uranyl cleavage by the presence of hexamminecobalt (III) or spermidine. These ions are known to induce the folded conformation of the four-way junction with high efficiency, suggesting a direct competition between the ions. By contrast, magnesium ions failed to generate a similar protection against photocleavage. These results suggest that the uranyl, hexamminecobalt (III) and spermidine ions compete for the same high affinity binding site on the junction. This site is located at the centre of the junction, at the point where the exchanging strands pass between the stacked helices. We believe that we have observed the first known example of a metal ion 'footprint' on a folded nucleic acid structure. Images PMID:8156988

  7. 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

  8. Metal-ion-ligand interactions in thermotropic liquid crystals

    NASA Astrophysics Data System (ADS)

    Diehl, P.; Wasser, H. R.; Gowda, G. A. Nagana; Suryaprakash, N.; Khetrapal, C. L.

    1989-07-01

    The interactions of lithium perchlorate with ligands such as dimethyl sulphoxide, acetonitrile, pyridine and the Schiff base liquid crystals are investigated. The experiments open a new field for the study of metal-ion-ligand interactions in thermotropic liquid crystals.

  9. Kinetic Analysis of Metal Ions: An Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Williams, Kathryn R.

    1985-01-01

    Reports on the adaptation of a kinetic method of analysis of metal ions for use in an undergraduate teaching laboratory. Background information, procedures used, and analysis of typical results obtained are provided. (JN)

  10. A Novel Methodology for Metal Ion Separation Based on Molecularly Imprinting

    SciTech Connect

    Zuo, Xiaobin; Mosha, Donnati; Hassan, Mansour M.; Givens, Richard S.; Busch, Daryle H.

    2004-03-31

    The siderophore-based extraction of iron from the soil by bacteria is proposed as a model for a new separation methodology labeled the soil poutice, a molecular device that would selectively retrieve the complex of a targeted metal ion. In this report we described the synthesis and characterization of molecularly imprinted polymers and their application in the specific recognition of macrocyclic metal complexes. The imprinting is based on non-covalent interactions such as hydrogen bonding, electrostatic attractions and minor metal-ligand coordination. Good rebinding capacity for the imprinting metal complex was observed in acetonitrile as well as in water. The polymers are resistant to strong acids and oxidizing agents and showed an increase of rebinding capacity during cycles of reuse. The imprinting procedure, combined with the previously known selective chelation of macrocyclic ligands, supports the feasibility of a new methodology that can be used to extract waste metal ions effectively and selectively from soils and ground water.

  11. Ion exchange extraction of heavy metals from wastewater sludges.

    PubMed

    Al-Enezi, G; Hamoda, M F; Fawzi, N

    2004-01-01

    Heavy metals are common contaminants of some industrial wastewater. They find their way to municipal wastewaters due to industrial discharges into the sewerage system or through household chemicals. The most common heavy metals found in wastewaters are lead, copper, nickel, cadmium, zinc, mercury, arsenic, and chromium. Such metals are toxic and pose serious threats to the environment and public health. In recent years, the ion exchange process has been increasingly used for the removal of heavy metals or the recovery of precious metals. It is a versatile separation process with the potential for broad applications in the water and wastewater treatment field. This article summarizes the results obtained from a laboratory study on the removal of heavy metals from municipal wastewater sludges obtained from Ardhiya plant in Kuwait. Data on heavy metal content of the wastewater and sludge samples collected from the plant are presented. The results obtained from laboratory experiments using a commercially available ion exchange resin to remove heavy metals from sludge were discussed. A technique was developed to solubilize such heavy metals from the sludge for subsequent treatment by the ion exchange process. The results showed high efficiency of extraction, almost 99.9%, of heavy metals in the concentration range bound in wastewater effluents and sludges. Selective removal of heavy metals from a contaminated wastewater/sludge combines the benefits of being economically prudent and providing the possibility of reuse/recycle of the treated wastewater effluents and sludges.

  12. Frictional and morphological characteristics of ion plated soft, metallic films

    NASA Technical Reports Server (NTRS)

    Spalvins, T.; Buzek, B.

    1981-01-01

    Ion plated metallic films in contrast to films applied by other deposition techniques offer a lower friction coefficient, longer endurance lives and exhibit a gradual increase in friction coefficient after the film has been worn off. The friction coefficients of metallic films are affected by the degree of adherence, thickness and nucleation and growth characteristics during ion plating lead to a fine, continuous crystalline structure, which contributes to a lower friction coefficient.

  13. 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.

  14. 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.

  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. 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.

  17. 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.

  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. Production of negative hydrogen ions on metal grids

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  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. 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

    selective gas permeability. Much more commonly than above, polyimide films are prepared by casting the film as the poly(amic acid) precursor which is then converted to the imidized form during the thermal cure cycle. Very limited success was achieved in the past in adding lanthanide metal ions to the amide precursors because of gellation and lack of solubility. With the use of the diketone ligands cited above, the solubility and gellation problems were overcome. However, the films after curing were clear but unacceptably brittle. Attempts to overcome this cure embrittlement problem are in progress.

  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. New polymer-supported ion-complexing agents: design, preparation and metal ion affinities of immobilized ligands.

    PubMed

    Alexandratos, Spiro D

    2007-01-31

    Polymer-supported reagents are comprised of crosslinked polymer networks that have been modified with ligands capable of selective metal ion complexation. Applications of these polymers are in environmental remediation, ion chromatography, sensor technology, and hydrometallurgy. Bifunctional polymers with diphosphonate/sulfonate ligands have a high selectivity for actinide ions. The distribution coefficient for the uranyl ion from 1 M nitric acid is 70,000, compared to 900 for the monophosphonate/sulfonate polymer and 200 for the sulfonic acid ion-exchange resin. A bifunctional trihexyl/triethylammonium polymer has a high affinity and selectivity for pertechnetate and perchlorate anions from groundwater. In one example, its distribution coefficient for perchlorate ions in the presence of competing anions is 3,300,000, compared to 203,180 for a commercially available anion-exchange resin. Polystyrene modified with N-methyl-D-glucamine ligands is capable of selectively complexing arsenate from groundwater. It complexes 99% of the arsenate present in a solution of 100 mg/L arsenate with 560 mg/L sulfate ions. Its selectivity is retained even in the presence of 400 mg/L phosphate. There is no affinity for arsenate above pH 9, allowing for the polymer to be regenerated with moderate alkali solution. In studies aimed at developing a Hg(II)-selective resin, simple amine resins were found to have a high Hg(II) affinity and that affinity is dependent upon the solution pH and the counterion.

  4. 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.

  5. Method and apparatus for ion sequestration and a nanostructured metal phosphate

    DOEpatents

    Mattigod, Shas V.; Fryxell, Glen E.; Li, Xiaohong; Parker, Kent E.; Wellman, Dawn M.

    2010-04-06

    A nanostructured substance, a process for sequestration of ionic waste, and an ion-sequestration apparatus are disclosed in the specification. The nanostructured substance can comprise a Lewis acid transition metal bound to a phosphate, wherein the phosphate comprises a primary structural component of the substance and the Lewis acid transition metal is a reducing agent. The nanostructured substance has a Brunner-Emmet-Teller (BET) surface area greater than or equal to approximately 100 m.sup.2/g, and a distribution coefficient for an analyte, K.sub.d, greater than or equal to approximately 5000 ml/g. The process can comprise contacting a fluid and a nanostructured metal phosphate. The apparatus can comprise a vessel and a nanostructured metal phosphate. The vessel defines a volume wherein a fluid contacts the nanostructured metal phosphate.

  6. Estimating the acidity of transition metal hydride and dihydrogen complexes by adding ligand acidity constants.

    PubMed

    Morris, Robert H

    2014-02-01

    A simple equation (pKa(THF) = ∑AL + Ccharge + Cnd + Cd6) can be used to obtain an estimate of the pKa of diamagnetic transition metal hydride and dihydrogen complexes in tetrahydrofuran, and, by use of conversion equations, in other solvents. It involves adding acidity constants AL for each of the ligands in the 5-, 6-, 7-, or 8-coordinate conjugate base complex of the hydride or dihydrogen complex along with a correction for the charge (Ccharge = -15, 0 or 30 for x = +1, 0 or -1 charge, respectively) and the periodic row of the transition metal (Cnd = 0 for 3d or 4d metal, 2 for 5d metal) as well as a correction for d(6) octahedral acids (Cd6 = 6 for d(6) metal ion in the acid, 0 for others) that are not dihydrogen complexes. Constants AL are provided for 13 commonly occurring ligand types; of these, nine neutral ligands are correlated with Lever's electrochemical ligand parameters EL. This method gives good estimates of the over 170 literature pKa values that range from less than zero to 50 with a standard deviation of 3 pKa units for complexes of the metals chromium to nickel, molybdenum, ruthenium to palladium, and tungsten to platinum in the periodic table. This approach allows a quick assessment of the acidity of hydride complexes found in nature (e.g., hydrogenases) and in industry (e.g., catalysis and hydrogen energy applications). The pKa values calculated for acids that have bulky or large bite angle chelating ligands deviate the most from this correlation. The method also provides an estimate of the base strength of the deprotonated form of the complex.

  7. Estimating the acidity of transition metal hydride and dihydrogen complexes by adding ligand acidity constants.

    PubMed

    Morris, Robert H

    2014-02-01

    A simple equation (pKa(THF) = ∑AL + Ccharge + Cnd + Cd6) can be used to obtain an estimate of the pKa of diamagnetic transition metal hydride and dihydrogen complexes in tetrahydrofuran, and, by use of conversion equations, in other solvents. It involves adding acidity constants AL for each of the ligands in the 5-, 6-, 7-, or 8-coordinate conjugate base complex of the hydride or dihydrogen complex along with a correction for the charge (Ccharge = -15, 0 or 30 for x = +1, 0 or -1 charge, respectively) and the periodic row of the transition metal (Cnd = 0 for 3d or 4d metal, 2 for 5d metal) as well as a correction for d(6) octahedral acids (Cd6 = 6 for d(6) metal ion in the acid, 0 for others) that are not dihydrogen complexes. Constants AL are provided for 13 commonly occurring ligand types; of these, nine neutral ligands are correlated with Lever's electrochemical ligand parameters EL. This method gives good estimates of the over 170 literature pKa values that range from less than zero to 50 with a standard deviation of 3 pKa units for complexes of the metals chromium to nickel, molybdenum, ruthenium to palladium, and tungsten to platinum in the periodic table. This approach allows a quick assessment of the acidity of hydride complexes found in nature (e.g., hydrogenases) and in industry (e.g., catalysis and hydrogen energy applications). The pKa values calculated for acids that have bulky or large bite angle chelating ligands deviate the most from this correlation. The method also provides an estimate of the base strength of the deprotonated form of the complex. PMID:24410025

  8. 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.

  9. 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

  10. Models of metal binding structures in fulvic acid from the Suwannee River, Georgia

    USGS Publications Warehouse

    Leenheer, J.A.; Brown, G.K.; MacCarthy, P.; Cabaniss, S.E.

    1998-01-01

    Fulvic acid, isolated from the Suwannee River, Georgia, was assessed for its ability to bind Ca2+, Cd2+, Cu2+, Ni2+, and Zn2+ ions at pH 6 before and after extensive fractionation that was designed to reveal the nature of metal binding functional groups. The binding constant for Ca2+ ion had the greatest increase of all the ions in a metal binding fraction that was selected for intensive characterization for the purpose of building quantitative average model structures. The 'metal binding' fraction was characterized by quantitative 13C NMR, 1H NMR, and FT-1R spectrometry and elemental, titrimetric, and molecular weight determinations. The characterization data revealed that carboxyl groups were clustered in short- chain aliphatic dibasic acid structures. The Ca2+ binding data suggested that ether-substituted oxysuccinic acid structures are good models for the metal binding sites at pH 6. Structural models were derived based upon oxidation and photolytic rearrangements of cutin, lignin, and tannin precursors. These structural models rich in substituted dibasic acid structures revealed polydentate binding sites with the potential for both inner-sphere and outer-sphere type binding. The majority of the fulvic acid molecule was involved with metal binding rather than a small substructural unit.Fulvic acid, isolated from the Suwannee River, Georgia, was assessed for its ability to bind Ca2+, Cd2+, Cu2+, Ni2+, and Zn2+ ions at pH 6 before and after extensive fractionation that was designed to reveal the nature of metal binding functional groups. The binding constant for Ca2+ ion had the greatest increase of all the ions in a metal binding fraction that was selected for intensive characterization for the purpose of building quantitative average model structures. The `metal binding' fraction was characterized by quantitative 13C NMR, 1H NMR, and FT-IR spectrometry and elemental, titrimetric, and molecular weight determinations. The characterization data revealed that

  11. 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.

  12. Potentiometric determination of free acidity in presence of hydrolysable ions and a sequential determination of hydrazine.

    PubMed

    Ganesh, S; Khan, Fahmida; Ahmed, M K; Pandey, S K

    2011-08-15

    A simple potentiometric method for the determination of free acidity in presence of hydrolysable ions and sequential determination of hydrazine is developed and described. Both free acid and hydrazine are estimated from the same aliquot. In this method, free acid is titrated with standard sodium carbonate solution after the metal ions in solutions are masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. This method is especially applicable to all ranges of nitric acid and heavy metal ion concentration relevant to Purex process used for nuclear fuel reprocessing. The overall recovery of nitric acid is 98.9% with 1.2% relative standard deviation. Hydrazine content has also been determined in the same aliquot with a recovery of nitric acid is 99% with 2% relative standard deviation. The major advantage of the method is that generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal. PMID:21726724

  13. Modification of porous starch for the adsorption of heavy metal ions from aqueous solution.

    PubMed

    Ma, Xiaofei; Liu, Xueyuan; Anderson, Debbie P; Chang, Peter R

    2015-08-15

    Porous starch xanthate (PSX) and porous starch citrate (PSC) were prepared in anticipation of the attached xanthate and carboxylate groups respectively forming chelation and electrostatic interactions with heavy metal ions in the subsequent adsorption process. The lead(II) ion was selected as the model metal and its adsorption by PSX and PSC was characterized. The adsorption capacity was highly dependent on the carbon disulfide/starch and citric acid/starch mole ratios used during preparation. The adsorption behaviors of lead(II) ion on PSXs and PSCs fit both the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity from the Langmuir isotherm equation reached 109.1 and 57.6 mg/g for PSX and PSC when preparation conditions were optimized, and the adsorption times were just 20 and 60 min, respectively. PSX and PSC may be used as effective adsorbents for removal of heavy metals from contaminated liquid. PMID:25794731

  14. Modification of porous starch for the adsorption of heavy metal ions from aqueous solution.

    PubMed

    Ma, Xiaofei; Liu, Xueyuan; Anderson, Debbie P; Chang, Peter R

    2015-08-15

    Porous starch xanthate (PSX) and porous starch citrate (PSC) were prepared in anticipation of the attached xanthate and carboxylate groups respectively forming chelation and electrostatic interactions with heavy metal ions in the subsequent adsorption process. The lead(II) ion was selected as the model metal and its adsorption by PSX and PSC was characterized. The adsorption capacity was highly dependent on the carbon disulfide/starch and citric acid/starch mole ratios used during preparation. The adsorption behaviors of lead(II) ion on PSXs and PSCs fit both the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity from the Langmuir isotherm equation reached 109.1 and 57.6 mg/g for PSX and PSC when preparation conditions were optimized, and the adsorption times were just 20 and 60 min, respectively. PSX and PSC may be used as effective adsorbents for removal of heavy metals from contaminated liquid.

  15. Gallic Acid, Ellagic Acid and Pyrogallol Reaction with Metallic Iron

    NASA Astrophysics Data System (ADS)

    Jaén, J. A.; González, L.; Vargas, A.; Olave, G.

    2003-06-01

    The reaction between gallic acid, ellagic acid and pyrogallol with metallic iron was studied using infrared and Mössbauer spectroscopy. Most hydrolysable tannins with interesting anticorrosive or inhibition properties are structurally related to these compounds, thus they may be used as models for the study of hydrolysable tannins and related polyphenols. The interaction was followed up to 3 months. Results indicated two different behaviors. At polyphenol concentrations higher than 1% iron converts to sparingly soluble and amorphous ferric (and ferrous) polyphenolate complexes. At lower concentrations (0.1%), the hydrolysis reactions are dominant, resulting in the formation of oxyhydroxides, which can be further reduced to compounds like magnetite by the polyphenols.

  16. Metal ions affecting the neurological system.

    PubMed

    Pohl, Hana R; Roney, Nickolette; Abadin, Henry G

    2011-01-01

    Several individual metals including aluminum, arsenic, cadmium, lead, manganese, and mercury were demonstrated to affect the neurological system. Metals are ubiquitous in the environment. Environmental and occupational exposure to one metal is likely to be accompanied by exposure to other metals, as well. It is, therefore, expected that interactions or "joint toxic actions" may occur in populations exposed to mixtures of metals or to mixtures of metals with other chemicals. Some metals seem to have a protective role against neurotoxicity of other metals, yet other interactions may result in increased neurotoxicity. For example, zinc and copper provided a protective role in cases of lead-induced neurotoxicity. In contrast, arsenic and lead co-exposure resulted in synergistic effects. Similarly, information is available in the current literature on interactions of metals with some organic chemicals such as ethanol, polychlorinated biphenyls, and pesticides. In depth understanding of the toxicity and the mechanism of action (including toxicokinetics and toxicodynamics) of individual chemicals is important for predicting the outcomes of interactions in mixtures. Therefore, plausible mechanisms of action are also described.

  17. Ion source metal-arc fault current protection circuit

    SciTech Connect

    deVries, G.J.; Lietzke, A.F.; van Os, C.F.A.; Stearns, J.W. )

    1991-12-01

    Ion sources can be damaged by arcs between metallic components of the source if these arcs are permitted to last. The negative-biased low-work-function converter in a surface conversion negative ion source is especially susceptible to metal-arc breakdown damage. Here an electronic circuit for minimizing the damage caused by such an arc is described. The circuit uses a transistor switch and an inductor in series with the converter bias power supply to limit the damage during the metal-arc breakdown.

  18. 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)

  19. 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.

  20. Hall transport of divalent metal ion modified DNA lattices

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    We investigate the Hall transport characteristics of double-crossover divalent metal ion (Cu2+, Ni2+, Zn2+, and Co2+)-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 (Cs) 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 (≤Cs) and the nonspecific aggregates (>Cs) 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. 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.

  2. 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.

  3. Multiple DNA architectures with the participation of inorganic metal ions.

    PubMed

    Wei, Guangcheng; Dong, Renhao; Gao, Xuedong; Wang, Dong; Feng, Lei; Song, Shasha; Dong, Shuli; Song, Aixin; Hao, Jingcheng

    2014-09-10

    Here we develop a synthetic protocol for assembling DNA with participating metal ions into multiple shapes. DNA molecules first form coordination complexes with metal ions and these coordination complexes become nucleation sites for primary crystals of metal inorganic salt, and then elementary units of space-filling architectures based on specific geometry form, and finally elementary units assemble into variously larger multiple architectures according to different spatial configurations. We anticipate that our strategy for self-assembling various custom architectures is applicable to most biomolecules possessing donor atoms that can form coordination complexes with metal ions. These multiple architectures provide a general platform for the engineering and assembly of advanced materials possessing features on the micrometer scale and having novel activity.

  4. Recovery of dilute metal ions by biosorption on river algae and its component

    SciTech Connect

    Fujita, Toyohisa; Kogita, Hiroki; Mamiya, Mitsuo; Yen, W.T.

    1995-12-31

    Green algae taken from an acidic mine drainage and blue-green algae take from an alkaline hot spring stream were collected and tested for their ability to recover or remove dilute metal ions. Experimental results demonstrated that unwashed blue-green algae and washed green algae effectively adsorbed base metals ions and eluted the at pH 1. It was also found that washed and dried algae adsorbed precious metal ions more effectively than unwashed algae. For example, the washed and dried blue-green algae was capable of adsorbing 0.31 kg of gold pre kg of algae. The gold from tetrachloroaurate solution which was adsorbed on washed blue-green algae was found to change to a metallic state following initial metal binding. In the case of a dilute gold complex solution leached with thiourea, only a small amount of gold could be captured by algae. Further experiments were conducted on components of the algae, such as alginic acid, agar, cellulose and chitin and mixtures of these components, in order to determine their contribution to metal adsorption characteristics. However, a mixture of these two components demonstrated both good adsorption and desorption characteristics indicating an interaction between the individual components.

  5. Effect of Different Metal Ions on the Biological Properties of Cefadroxil

    PubMed Central

    Auda, Sayed H.; Knütter, Ilka; Bretschneider, Beate; Brandsch, Matthias; Mrestani, Yahya; Große, Cornelia; Neubert, Reinhard H. H.

    2009-01-01

    The effect of different metal ions on the intestinal transport and the antibacterial activity of cefadroxil [(6R,7R)-7-{[(2R)-2-amino-2-(4-hydroxyphenyl)acetyl]amino}-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid] was investigated. The [14C]Gly-Sar uptake via PEPT1 was inhibited by Zn2+ and Cu2+ treatment in a concentration-dependent manner (Ki values 107 ± 23 and 19 ± 5 µM, respectively). Kinetic analysis showed that the Kt of Gly-Sar uptake was increased 2-fold in the presence of zinc sulphate (150 µM) whereas the Vmax value were not affected suggesting that zinc ions inhibited Gly-Sar uptake by PEPT1 in a competitively manner. Ni2+ exhibited moderate inhibitory effect, whereas Co2+, Mg2+, Al3+ ions showed no inhibitory effect on Gly-Sar uptake via PEPT1. Subsequently, we examined the effect of Zn2+ and Al3+ ions on the transepithelial transport of cefadroxil across Caco-2 cells cultured on permeable supports. The results showed that zinc ions inhibited the transepithelial flux of cefadroxil at Caco-2 cell monolayers while Al3+ ions had no effect. The interaction of cephalosporins with the metal ions could suggest negative effects of some metal ions on the clinical aspects of small intestinal peptide and drug transport. Finally, the effect of Zn2+, Cu2+ and Al3+ ions on the antibacterial activity of cefadroxil was tested. It was found that there is no significant difference between the activity of cefadroxil and the cefadroxil metal ion complexes studied against the investigated sensitive bacterial species. PMID:27713232

  6. Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

    SciTech Connect

    Bartsch, R.A.

    1994-12-31

    During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The influence of structural variations within lipophilic acyclic polyether dicarboxylic acids upon competitive solvent extraction of alkaline earth cations has been probed. Also a new chromogenic, di-ionizable crown ether with extremely high selectivity for Hg{sup 2+} has been discovered.

  7. Technological applications arising from the interactions of DNA bases with metal ions.

    PubMed

    Park, Ki Soo; Park, Hyun Gyu

    2014-08-01

    An intense interest has grown in the unique interactions of nucleic acids with metal ions, which lead to the formation of metal-base pairs and the generation of fluorescent nanomaterials. In this review, different types of metal-base pairs, especially those formed from naturally occurring nucleosides, are described with emphasis also being given to recent advances made in employing these complexes to govern enzymatic reactions. The review also contains a comprehensive description of DNA-templated inorganic nanomaterials such as silver nanoclusters which possess excellent fluorescence properties. Finally, a summary is given about how these materials have led to recent advances in the field of nanobiotechnology.

  8. Technological applications arising from the interactions of DNA bases with metal ions.

    PubMed

    Park, Ki Soo; Park, Hyun Gyu

    2014-08-01

    An intense interest has grown in the unique interactions of nucleic acids with metal ions, which lead to the formation of metal-base pairs and the generation of fluorescent nanomaterials. In this review, different types of metal-base pairs, especially those formed from naturally occurring nucleosides, are described with emphasis also being given to recent advances made in employing these complexes to govern enzymatic reactions. The review also contains a comprehensive description of DNA-templated inorganic nanomaterials such as silver nanoclusters which possess excellent fluorescence properties. Finally, a summary is given about how these materials have led to recent advances in the field of nanobiotechnology. PMID:24832070

  9. Acid-sensing ion channels under hypoxia

    PubMed Central

    Yingjun, Guo; Xun, Qu

    2013-01-01

    Hypoxia represents the lack of oxygen below the basic level, and the range of known channels related to hypoxia is continually increasing. Since abnormal hypoxia initiates pathological processes in numerous diseases via, to a great degree, producing acidic microenvironment, the significance of these channels in this environment has, until now, remained completely unknown. However, recent discovery of acid-sensing ion channels (ASICs) have enhanced our understanding of the hypoxic channelome. They belong to the degenerin/epithelial Na+ channel family and function once extracellular pH decreases to a certain level. So does the ratiocination emerge that ASICs participate in many hypoxia-induced pathological processes, including pain, apoptosis, malignancy, which all appear to involve them. Since evidence suggests that activity of ASICs is altered under pathological hypoxia, future studies are needed to deeply explore the relationship between ASICs and hypoxia, which may provide a progressive understanding of hypoxic effects in cancer, arthritis, intervertebral disc degeneration, ischemic brain injury and so on. PMID:23764948

  10. Does Cation Size Affect Occupancy and Electrostatic Screening of the Nucleic Acid Ion Atmosphere?

    PubMed

    Gebala, Magdalena; Bonilla, Steve; Bisaria, Namita; Herschlag, Daniel

    2016-08-31

    Electrostatics are central to all aspects of nucleic acid behavior, including their folding, condensation, and binding to other molecules, and the energetics of these processes are profoundly influenced by the ion atmosphere that surrounds nucleic acids. Given the highly complex and dynamic nature of the ion atmosphere, understanding its properties and effects will require synergy between computational modeling and experiment. Prior computational models and experiments suggest that cation occupancy in the ion atmosphere depends on the size of the cation. However, the computational models have not been independently tested, and the experimentally observed effects were small. Here, we evaluate a computational model of ion size effects by experimentally testing a blind prediction made from that model, and we present additional experimental results that extend our understanding of the ion atmosphere. Giambasu et al. developed and implemented a three-dimensional reference interaction site (3D-RISM) model for monovalent cations surrounding DNA and RNA helices, and this model predicts that Na(+) would outcompete Cs(+) by 1.8-2.1-fold; i.e., with Cs(+) in 2-fold excess of Na(+) the ion atmosphere would contain an equal number of each cation (Nucleic Acids Res. 2015, 43, 8405). However, our ion counting experiments indicate that there is no significant preference for Na(+) over Cs(+). There is an ∼25% preferential occupancy of Li(+) over larger cations in the ion atmosphere but, counter to general expectations from existing models, no size dependence for the other alkali metal ions. Further, we followed the folding of the P4-P6 RNA and showed that differences in folding with different alkali metal ions observed at high concentration arise from cation-anion interactions and not cation size effects. Overall, our results provide a critical test of a computational prediction, fundamental information about ion atmosphere properties, and parameters that will aid in the

  11. 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

  12. 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.

  13. Force Field for Mg(2+), Mn(2+), Zn(2+), and Cd(2+) Ions That Have Balanced Interactions with Nucleic Acids.

    PubMed

    Panteva, Maria T; Giambaşu, George M; York, Darrin M

    2015-12-17

    Divalent metal ions are of fundamental importance to the function and folding of nucleic acids. Divalent metal ion-nucleic acid interactions are complex in nature and include both territorial and site specific binding. Commonly employed nonbonded divalent ion models, however, are often parametrized against bulk ion properties and are subsequently utilized in biomolecular simulations without considering any data related to interactions at specific nucleic acid sites. Previously, we assessed the ability of 17 different nonbonded Mg(2+) ion models to reproduce different properties of Mg(2+) in aqueous solution including radial distribution functions, solvation free energies, water exchange rates, and translational diffusion coefficients. In the present work, we depart from the recently developed 12-6-4 potential models for divalent metal ions developed by Li and Merz and tune the pairwise parameters for Mg(2+), Mn(2+), Zn(2+), and Cd(2+) binding dimethyl phosphate, adenosine, and guanosine in order to reproduce experimental site specific binding free energies derived from potentiometric pH titration data. We further apply these parameters to investigate a metal ion migration previously proposed to occur during the catalytic reaction of the hammerhead ribozyme. The new parameters are shown to be accurate and balanced for nucleic acid binding in comparison with available experimental data and provide an important tool for molecular dynamics and free energy simulations of nucleic acids where these ions may exhibit different binding modes.

  14. Force Field for Mg2+, Mn2+, Zn2+ and Cd2+ Ions That Have Balanced Interactions with Nucleic Acids

    PubMed Central

    Panteva, Maria T.; Giambaşu, George M.; York, Darrin M.

    2016-01-01

    Divalent metal ions are of fundamental importance to the function and folding of nucleic acids. Divalent metal ion - nucleic acid interactions are complex in nature and include both territorial, as well as site specific binding. Commonly employed non-bonded divalent ion models, however, are often parametrized against bulk ion properties and are subsequently utilized in biomolecular simulations without considering any data related to interactions at specific nucleic acid sites. Previously, we assessed the ability of 17 different non-bonded Mg2+ ion models to reproduce different properties of Mg2+ in aqueous solution including radial distribution functions, solvation free energies, water exchange rates and translational diffusion coefficients. In the present work, we depart from the recently developed 12-6-4 potential models for divalent metal ions developed by Li and Merz and tune the pairwise parameters for Mg2+, Mn2+, Zn2+ and Cd2+ binding dimethyl phosphate, adenosine and guanosine in order to reproduce experimental site specific binding free energies derived from potentiometric pH titration data. We further apply these parameters to investigate a metal ion migration previously proposed to occur during the catalytic reaction of the hammerhead ribozyme. The new parameters are shown to be accurate and balanced for nucleic acid binding in comparison with available experimental data, and provide an important tool for molecular dynamics and free energy simulations of nucleic acids where these ions may exhibit different binding modes. PMID:26583536

  15. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm.

  16. 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.

  17. 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.

  18. Solvent effects and alkali metal ion catalysis in phosphodiester hydrolysis.

    PubMed

    Gomez-Tagle, Paola; Vargas-Zúñiga, Idania; Taran, Olga; Yatsimirsky, Anatoly K

    2006-12-22

    The kinetics of the alkaline hydrolysis of bis(p-nitrophenyl) phosphate (BNPP) have been studied in aqueous DMSO, dioxane, and MeCN. In all solvent mixtures the reaction rate steadily decreases to half of its value in pure water in the range of 0-70 vol % of organic cosolvent and sharply increases in mixtures with lower water content. Correlations based on different scales of solvent empirical parameters failed to describe the solvent effect in this system, but it can be satisfactorily treated in terms of a simplified stepwise solvent-exchange model. Alkali metal ions catalyze the BNPP hydrolysis but do not affect the rate of hydrolysis of neutral phosphotriester p-nitrophenyl diphenyl phosphate in DMSO-rich mixtures. The catalytic activity decreases in the order Li+ > Na+ > K+ > Rb+ > Cs+. For all cations except Na+, the reaction rate is first-order in metal ion. With Na+, both first- and second-order kinetics in metal ions are observed. Binding constants of cations to the dianionic transition state of BNPP alkaline hydrolysis are of the same order of magnitude and show a similar trend as their binding constants to p-nitrophenyl phosphate dianion employed as a transition-state model. The appearance of alkali metal ion catalysis in a medium, which solvates metal ions stronger than water, is attributed to the increased affinity of cations to dianions, which undergo a strong destabilization in the presence of an aprotic dipolar cosolvent.

  19. 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.

  20. Effects of metal ions on disinfection byproduct formation during chlorination of natural organic matter and surrogates.

    PubMed

    Zhao, Yu; Yang, Hong-wei; Liu, Shi-ting; Tang, Shun; Wang, Xiao-mao; Xie, Yuefeng F

    2016-02-01

    The effects of calcium, cupric, ferrous and ferric ions on the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) were investigated using natural organic matter (NOM), small molecular weight NOM surrogates and natural water samples. The results showed that the effects were greatly dependent on the disinfection byproduct (DBP) precursor structure and molecular weight, and metal ions species. While using NOM as precursors, addition of 4.00 mM calcium ions increased the formation of THMs, dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs) by 24-47%, 51-61% and 15-25%, respectively. Addition of cupric ions at 0.02 mM increased the formation of THMs and DHAAs by 74-83% and 90-100%, respectively, but decreased the formation of THAAs by 26-27%. Similar effect was not observed when 0.04 mM ferrous or ferric ions were added. The effects of calcium and cupric ions on DBP formation were generally more evident for the NOM surrogates than that for NOM. The primary catalytic effect of calcium ions was due to complexation and less sensitive to molecular structure or weight, while that of cupric ions was attributed to redox reactions and greatly dependent on molecular structure. Both ferric and ferrous iron had substantial effects on the DBP formation of surrogates (citric acid and catechol in particular), which implied that the catalytic effects of ferric and ferrous iron mainly depended on molecular weight. The catalytic effect of cupric ions was also observed on natural water samples, while the effects of calcium, ferrous and ferric ions on natural water samples were not evident.

  1. Effects of metal ions on disinfection byproduct formation during chlorination of natural organic matter and surrogates.

    PubMed

    Zhao, Yu; Yang, Hong-wei; Liu, Shi-ting; Tang, Shun; Wang, Xiao-mao; Xie, Yuefeng F

    2016-02-01

    The effects of calcium, cupric, ferrous and ferric ions on the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) were investigated using natural organic matter (NOM), small molecular weight NOM surrogates and natural water samples. The results showed that the effects were greatly dependent on the disinfection byproduct (DBP) precursor structure and molecular weight, and metal ions species. While using NOM as precursors, addition of 4.00 mM calcium ions increased the formation of THMs, dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs) by 24-47%, 51-61% and 15-25%, respectively. Addition of cupric ions at 0.02 mM increased the formation of THMs and DHAAs by 74-83% and 90-100%, respectively, but decreased the formation of THAAs by 26-27%. Similar effect was not observed when 0.04 mM ferrous or ferric ions were added. The effects of calcium and cupric ions on DBP formation were generally more evident for the NOM surrogates than that for NOM. The primary catalytic effect of calcium ions was due to complexation and less sensitive to molecular structure or weight, while that of cupric ions was attributed to redox reactions and greatly dependent on molecular structure. Both ferric and ferrous iron had substantial effects on the DBP formation of surrogates (citric acid and catechol in particular), which implied that the catalytic effects of ferric and ferrous iron mainly depended on molecular weight. The catalytic effect of cupric ions was also observed on natural water samples, while the effects of calcium, ferrous and ferric ions on natural water samples were not evident. PMID:26454116

  2. 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

  3. 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.

  4. Unusual metal ion catalysis in an acyl-transferase ribozyme.

    PubMed

    Suga, H; Cowan, J A; Szostak, J W

    1998-07-14

    Most studies of the roles of catalytic metal ions in ribozymes have focused on inner-sphere coordination of the divalent metal ions to the substrate or ribozyme. However, divalent metal ions are strongly hydrated in water, and some proteinenzymes, such as Escherichia coli RNase H and exonuclease III, are known to use metal cofactors in their fully hydrated form [Duffy, T. H., and Nowak, T. (1985) Biochemistry 24, 1152-1160; Jou, R., and Cowan, J. A. (1991) J. Am. Chem. Soc. 113, 6685-6686]. It is therefore important to consider the possibility of outer-sphere coordination of catalytic metal ions in ribozymes. We have used an exchange-inert metal complex, cobalt hexaammine, to show that the catalytic metal ion in an acyl-transferase ribozyme acts through outer-sphere coordination. Our studies provide an example of a fully hydrated Mg2+ ion that plays an essential role in ribozyme catalysis. Kinetic studies of wild-type and mutant ribozymes suggest that a pair of tandem G:U wobble base pairs adjacent to the reactive center constitute the metal-binding site. This result is consistent with recent crystallographic studies [Cate, J. H., and Doudna, J. A. (1996) Structure 4, 1221-1229; Cate, J. H., Gooding, A. R., Podell, E., Zhou, K., Golden, B. L., Kundrot, C. E., Cech, T. R., and Doudna, J. A. (1996) Science 273, 1678-1685; Cate, J. H., Hanna, R. L., and Doudna, J. A. (1997) Nat. Struct. Biol. 4, 553-558] showing that tandem wobble base pairs are good binding sites for metal hexaammines. We propose a model in which the catalytic metal ion is bound in the major groove of the tandem wobble base pairs, is precisely positioned by the ribozyme within the active site, and stabilizes the developing oxyanion in the transition state. Our results may have significant implications for understanding the mechanism of protein synthesis [Noller, H. F., Hoffarth, V., and Zimniak, L. (1992) Science 256, 1416-1419].

  5. Metal ion modulated electron transfer in photosynthetic proteins.

    SciTech Connect

    Utschig, L. M.; Thurnauer, M. C.; Chemistry

    2004-07-01

    Photosynthetic purple bacterial reaction center (RC) proteins are ideal native systems for addressing basic questions regarding the nature of biological electron transfer because both the protein structure and the electron-transfer reactions are well-characterized. Metal ion binding to the RC can affect primary photochemistry and provides a probe for understanding the involvement of local protein environments in electron transfer. The RC has two distinct transition metal ion binding sites, the well-known non-heme Fe{sup 2+} site buried in the protein interior and a recently discovered Zn{sup 2+} site located on the surface of the protein. Fe{sup 2+} removal and Zn{sup 2+} binding systematically affect different electron-transfer steps in the RC. Factors involved in the metal ion alteration of RC electron transfer may provide a paradigm for other biological systems involved in electron transfer.

  6. Engineering Short Preorganized Peptide Sequences for Metal Ion Coordination: Copper(II) a Case Study.

    PubMed

    Lima, L M P; Iranzo, O

    2016-01-01

    Peptides are multidentate chiral ligands capable of coordinating different metal ions. Nowadays, they can be obtained with high yield and purity, thanks to the advances on peptide/protein chemistry as well as in equipment (peptide synthesizers). Based on the identity and length of their amino acid sequences, peptides can present different degrees of flexibility and folding. Although short peptide sequences (<20 amino acids) usually lack structure in solution, different levels of structural preorganization can be induced by introducing conformational constraints, such as β-turn/loop template sequences and backbone cyclization. For all these reasons, and the fact that one is not restricted to use proteinogenic amino acids, small peptidic scaffolds constitute a simple and versatile platform for the development of inorganic systems with tailor-made properties and functions. Here we outline a general approach to the design of short preorganized peptide sequences (10-16 amino acids) for metal ion coordination. Based on our experience, we present a general scheme for the design, synthesis, and characterization of these peptidic scaffolds and provide protocols for the study of their metal ion coordination properties. PMID:27586340

  7. Engineering Short Preorganized Peptide Sequences for Metal Ion Coordination: Copper(II) a Case Study.

    PubMed

    Lima, L M P; Iranzo, O

    2016-01-01

    Peptides are multidentate chiral ligands capable of coordinating different metal ions. Nowadays, they can be obtained with high yield and purity, thanks to the advances on peptide/protein chemistry as well as in equipment (peptide synthesizers). Based on the identity and length of their amino acid sequences, peptides can present different degrees of flexibility and folding. Although short peptide sequences (<20 amino acids) usually lack structure in solution, different levels of structural preorganization can be induced by introducing conformational constraints, such as β-turn/loop template sequences and backbone cyclization. For all these reasons, and the fact that one is not restricted to use proteinogenic amino acids, small peptidic scaffolds constitute a simple and versatile platform for the development of inorganic systems with tailor-made properties and functions. Here we outline a general approach to the design of short preorganized peptide sequences (10-16 amino acids) for metal ion coordination. Based on our experience, we present a general scheme for the design, synthesis, and characterization of these peptidic scaffolds and provide protocols for the study of their metal ion coordination properties.

  8. Applications of metal ions and liquid crystals for multiplex detection of DNA.

    PubMed

    Liu, Yanyang; Yang, Kun-Lin

    2015-02-01

    Many cations such as sodium ions have strong influence on anchoring behaviors of liquid crystals (LC). Since DNA is negatively charged and forms complex with metal ions, it is possible to form DNA/metal ions complex on surfaces to disrupt orientations of LC. This phenomenon is used to establish a principle for detecting surface immobilized DNA by using LC. In contrast, peptide nucleic acid (PNA) is electroneutral. It does not complex with metal ions or affect the orientations of LC. Therefore, PNA can be used as a probe to hybridize with specific DNA with a unique sequence, and the principle mentioned above can be used to detect the DNA target by using metal ions and LC. Based on this method, a 600bp DNA target in buffer can be detected with a limit of detection at 10fM. Unlike other fluorescence-based DNA assays, this LC-based detection method does not require labeling of DNA, and the test result can be viewed with the naked eye under a polarized microscope.

  9. 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.

  10. Efficient and selective adsorption of multi-metal ions using sulfonated cellulose as adsorbent.

    PubMed

    Dong, Cuihua; Zhang, Fulong; Pang, Zhiqiang; Yang, Guihua

    2016-10-20

    Contamination of heavy metal in wastewater has caused great concerns on human life and health. Developing an efficient material to eliminate the heavy metal ions has been a popular topic in recent years. In this work, sulfonated cellulose (SC) was explored as efficient adsorbent for metal ions in solution. Thermo gravimetric analyzer (TGA), X-ray diffraction (XRD) and Fourier-transform infrared spectrometer (FTIR) first analyzed the characterizations of SC. Subsequently, effects of solution pH, adsorbent loading, temperature and initial metal ion concentration on adsorption performance were investigated. The results showed that sulfonated modification of cellulose could decrease the crystallinity and thermostability of cellulose. Due to its excellent performance of adsorption to metal ions, SC could reach adsorption equilibrium status within as short as 2min. In multi-component solution, SC can orderly removes Fe(3+), Pb(2+) and Cu(2+) with excellent selectivity and high efficiency. In addition, SC is a kind of green and renewable adsorbent because it can be easily regenerated by treatment with acid or chelating liquors. The mechanism study shows that the sulfonic group play a major role in the adsorption process. PMID:27474562

  11. 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.

  12. 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

  13. 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.

  14. Formation and Fragmentation of Unsaturated Fatty Acid [M - 2H + Na]- Ions: Stabilized Carbanions for Charge-Directed Fragmentation

    NASA Astrophysics Data System (ADS)

    Thomas, Michael C.; Kirk, Benjamin B.; Altvater, Jens; Blanksby, Stephen J.; Nette, Geoffrey W.

    2013-12-01

    Fatty acids are long-chain carboxylic acids that readily produce [M - H]- ions upon negative ion electrospray ionization (ESI) and cationic complexes with alkali, alkaline earth, and transition metals in positive ion ESI. In contrast, only one anionic monomeric fatty acid-metal ion complex has been reported in the literature, namely [M - 2H + FeIICl]-. In this manuscript, we present two methods to form anionic unsaturated fatty acid-sodium ion complexes (i.e., [M - 2H + Na]-). We find that these ions may be generated efficiently by two distinct methods: (1) negative ion ESI of a methanolic solution containing the fatty acid and sodium fluoride forming an [M - H + NaF]- ion. Subsequent collision-induced dissociation (CID) results in the desired [M - 2H + Na]- ion via the neutral loss of HF. (2) Direct formation of the [M - 2H + Na]- ion by negative ion ESI of a methanolic solution containing the fatty acid and sodium hydroxide or bicarbonate. In addition to deprotonation of the carboxylic acid moiety, formation of [M - 2H + Na]- ions requires the removal of a proton from the fatty acid acyl chain. We propose that this deprotonation occurs at the bis-allylic position(s) of polyunsaturated fatty acids resulting in the formation of a resonance-stabilized carbanion. This proposal is supported by ab initio calculations, which reveal that removal of a proton from the bis-allylic position, followed by neutral loss of HX (where X = F- and -OH), is the lowest energy dissociation pathway.

  15. Formation and fragmentation of unsaturated fatty acid [M - 2H + Na]- ions: stabilized carbanions for charge-directed fragmentation.

    PubMed

    Thomas, Michael C; Kirk, Benjamin B; Altvater, Jens; Blanksby, Stephen J; Nette, Geoffrey W

    2014-02-01

    Fatty acids are long-chain carboxylic acids that readily produce [M - H](-) ions upon negative ion electrospray ionization (ESI) and cationic complexes with alkali, alkaline earth, and transition metals in positive ion ESI. In contrast, only one anionic monomeric fatty acid-metal ion complex has been reported in the literature, namely [M - 2H  +  Fe(II)Cl](-). In this manuscript, we present two methods to form anionic unsaturated fatty acid-sodium ion complexes (i.e., [M - 2H  +  Na](-)). We find that these ions may be generated efficiently by two distinct methods: (1) negative ion ESI of a methanolic solution containing the fatty acid and sodium fluoride forming an [M - H  +  NaF](-) ion. Subsequent collision-induced dissociation (CID) results in the desired [M - 2H  +  Na](-) ion via the neutral loss of HF. (2) Direct formation of the [M - 2H  +  Na](-) ion by negative ion ESI of a methanolic solution containing the fatty acid and sodium hydroxide or bicarbonate. In addition to deprotonation of the carboxylic acid moiety, formation of [M - 2H  +  Na](-) ions requires the removal of a proton from the fatty acid acyl chain. We propose that this deprotonation occurs at the bis-allylic position(s) of polyunsaturated fatty acids resulting in the formation of a resonance-stabilized carbanion. This proposal is supported by ab initio calculations, which reveal that removal of a proton from the bis-allylic position, followed by neutral loss of HX (where X = F(-) and (-)OH), is the lowest energy dissociation pathway. PMID:24338213

  16. 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.

  17. 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.

  18. 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.

  19. Immobilization and mineralization of metallic ions by bacteria

    SciTech Connect

    Ferris, F.G. )

    1990-01-01

    Although all forms of life are of critical importance biogeochemically, bacteria are especially significant. This uniqueness arises not only from the great diversity of environments populated by bacteria, but also because they perform many biogeochemical transformations that are carried out poorly or not at all by higher organisms. In addition, bacteria exhibit a profound ability to bind substantial quantities of metallic ions. This retention of metals is facilitated by electrostatic interactions with anionic carboxyl or phosphoryl groups in the structural polymers of the cells. The macromolecular constituents in cell walls and external sheaths of bacteria are particularly reactive, so metals tend to concentrate at the cell surface. These cellular structures also tenaciously bind metallic ions during diagenesis and serve as distinct nucleation sites for the formation of authigenic minerals. Evidence of microfossils in ancient sedimentary rocks suggests further that bacteria contributed to analogous processes in the past.

  20. 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.

  1. 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

  2. Evaluation of the factors governing metal biosorption and metal toxicity in acidic soil isolates

    SciTech Connect

    Pradhan, A.A.

    1992-06-09

    This research project was designed to determine the feasibility of microbial biosorption processes for removing metal ions from aqueous systems. A culture of acidic soil actinomycetes, grown in an aerobic environment in a completely mixed, semibatch culture reactor, was used for the study. The experiments were based on removal of copper and lead from test solutions. The anionic systems tested were nitrate, sulfate, and chloride. To determine the factors influencing biosorption and to characterize metal uptake by cellular and extracellular components of the microbial system, a dialysis testing procedure was developed. The effectiveness of biosorption was influenced by pH, initial concentration of metals, type of anionic system, and organic content of the system. respirometric runs were carried out to identify potential inhibitory effects of metal accumulation on microbial activities. In general, metal accumulation resulted in a decrease in the microbial oxygen uptake rate. Also, a lag phase was observed before the onset of the respiratory activity particularly at concentrations of copper and lead greater than 100 ppM.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. The crystallization of metal soaps and fatty acids in oil paint model systems.

    PubMed

    Hermans, Joen J; Keune, Katrien; van Loon, Annelies; Iedema, Piet D

    2016-04-28

    The formation and crystallization of metal soaps in oil paint layers is an important issue in the conservation of oil paintings. The chemical reactions and physical processes that are involved in releasing metal ions from pigments and fatty acids from the oil binder to form crystalline metal soap deposits have so far remained poorly understood. We have used a combination of differential scanning calorimetry (DSC) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) on model mixtures of palmitic acid, lead palmitate or zinc palmitate and linseed oil to study the transition from amorphous material to crystalline fatty acid or metal soap. This transition forms the final stage in the cascade of processes leading to metal soap-related oil paint degradation. Palmitic acid as well as the metal soaps showed nearly ideal solubility behavior. However, it was found that, near room temperature, both lead and zinc palmitate are practically insoluble in both liquid and partially polymerized linseed oil. Interestingly, the rate of metal soap and fatty acid crystallization decreased rapidly with the degree of linseed oil polymerization, possibly leading to systems where metal soaps are kinetically trapped in a semi-crystalline state. To explain the various morphologies of metal soap aggregates observed in oil paint layers, it is proposed that factors affecting the probability of crystal nucleation and the rate of crystal growth play a crucial role, like exposure to heat or cleaning solvents and the presence of microcracks. PMID:27039879

  8. The crystallization of metal soaps and fatty acids in oil paint model systems.

    PubMed

    Hermans, Joen J; Keune, Katrien; van Loon, Annelies; Iedema, Piet D

    2016-04-28

    The formation and crystallization of metal soaps in oil paint layers is an important issue in the conservation of oil paintings. The chemical reactions and physical processes that are involved in releasing metal ions from pigments and fatty acids from the oil binder to form crystalline metal soap deposits have so far remained poorly understood. We have used a combination of differential scanning calorimetry (DSC) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) on model mixtures of palmitic acid, lead palmitate or zinc palmitate and linseed oil to study the transition from amorphous material to crystalline fatty acid or metal soap. This transition forms the final stage in the cascade of processes leading to metal soap-related oil paint degradation. Palmitic acid as well as the metal soaps showed nearly ideal solubility behavior. However, it was found that, near room temperature, both lead and zinc palmitate are practically insoluble in both liquid and partially polymerized linseed oil. Interestingly, the rate of metal soap and fatty acid crystallization decreased rapidly with the degree of linseed oil polymerization, possibly leading to systems where metal soaps are kinetically trapped in a semi-crystalline state. To explain the various morphologies of metal soap aggregates observed in oil paint layers, it is proposed that factors affecting the probability of crystal nucleation and the rate of crystal growth play a crucial role, like exposure to heat or cleaning solvents and the presence of microcracks.

  9. 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.

  10. 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.

  11. How do energetic ions damage metallic surfaces?

    DOE PAGES

    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

  12. Ion-exchange properties of strontium hydroxyapatite under acidic conditions

    SciTech Connect

    Sugiyama, Shigeru; Nishioka, Hitoshi; Moriga, Toshihiro; Hayashi, Hiromu; Moffat, J.B.

    1998-09-01

    The ion exchange of strontium hydroxyapatite (SrHAp) with Pb{sup 2+} has been investigated under acidic conditions at 293 K. The addition of various acids to the exchanging solution enhanced the exchange capacity in the order HCl > HBr > HF > HNO{sub 3} > no acid, corresponding to the formation of halogen apatites with the former three acids or hydrogen phosphate with HNO{sub 3}. Since the ion-exchange capacity of SrHAp under nonacidic conditions is higher than that of chlorapatite, the aforementioned observations can be attributed to the participation of the protons introduced by the acids.z

  13. How Lewis acidic is your cation? Putting phosphenium ions on the fluoride ion affinity scale.

    PubMed

    Slattery, John M; Hussein, Sharifa

    2012-02-14

    The fluoride ion affinities (FIAs) of 33 phosphenium ions with a range of substituents were calculated using ab inito and DFT methods. The use of these FIA data as a measure of the Lewis acidities of phosphenium ions is described and the FIAs of the species studied here are compared to FIA data for more commonly encountered Lewis acids. Phosphenium ions are often stronger Lewis acids than neutral species, but in many cases are less Lewis acidic than highly electrophilic cations such as [Me(3)C](+) or [Me(3)Si](+). The impact of mesomeric, inductive and steric substituent effects on FIAs are discussed and related to the underlying electronic structures of different cation types. A comparison between the FIAs of known "free" phosphenium ions with those that are currently unknown and other highly electrophilic cations suggests that some diaryl- and dialkylphosphenium ions may yet be accessible under the right conditions. PMID:22159000

  14. Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity.

    PubMed

    Masi, Matteo; Iannelli, Renato; Losito, Gabriella

    2016-06-01

    The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable. PMID:26490900

  15. 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.

  16. 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

  17. Effect of nickelous and other metal ions on the inhibition of rumen bacterial metabolism by 3-(3'-isocyanocyclopent-2-enylidene)propionic acid and related isocyanides. [Phleum pratense

    SciTech Connect

    Brewer, D.; Calder, F.W.; Jones, G.A.; Tanguay, D.; Taylor, A.

    1986-01-01

    3-(3'-isocyanocyclopent-2-enylidene) propionic acid at a concentration of 2 to 5 ..mu..g ml/sup -1/ inhibited cellulose digestion by a mixed culture of rumen microorganisms and in other experiments inhibited the degradation of timothy had (Phleum pratense) in a digestibility test. At isocyanide concentrations of 12 ..mu..g ml/sup -1/ the fermentation activity of rumen fluid, measured by its dehydrogenase activity, was inhibited but not abolished. All of these isocyanide effects were reversed by the incorporation of nickelous ion into the solutions of the systems under study. The activity of 1 mol of isocyanide is reversed by about 1 mol of Ni/sup 2 +/ and, in the case of the cellulose digestion test, by about 1 mol of Co/sup 2 +/. Of some 15 other ions tested only Pd/sup 2 +/ and possibly chromium reversed the effect of the isocyanide.

  18. Simultaneous separation of nine metal ions and ammonium with nonaqueous capillary electrophoresis.

    PubMed

    Qu, Feng; Lin, Jin-Ming; Chen, Zuliang

    2004-01-01

    A simple and fast method for simultaneous separation of nine metal cations Ni2+, Cu2+, Co2+, Zn2+ Cd2+, K+, Na+, Mg2+ and Ca2+, and NH4+ in methanol is reported. The optimization for separation these 10 cations was achieved by using 0.5% acetic acid and 10 mM imidazole as electrolyte. The effects of water and ionic strength in the sample are discussed. The sensitive detection of transition metal ions was accomplished at 191 nm. The optimized method demonstrated high efficiency and good reproducibility, and was applied successfully to the qualitative and quantitative determination of transition metal ions in water samples, chemical reagents, oral zinc gluconate solution and human plasma. PMID:14753790

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Metal ion bombardment of onion skin cell wall

    NASA Astrophysics Data System (ADS)

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

    2005-01-01

    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 30 keV, 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.

  4. 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.

  5. Effect of H+ ion activity and Ca2+ on the toxicity of metals in the environment.

    PubMed Central

    Hutchinson, T C; Collins, F W

    1978-01-01

    The role of acidity in determining and restricting plant distribution and performance is discussed. In soils especially, a key effect of H+ ion concentration is on the solubility of potentially toxic heavy metals such as aluminum, managenese, zinc, iron, copper, and nickel. Al has been reported from many studies since the 1920's as the key determining toxic factor in acid soils. Some acid-tolerant species have been shown to be especially tolerant of Al, and mechanisms of tolerance have been suggested. Mn is also a commonly toxic factor at soil pH less than 5.0. Calcium has been shown to alleviate Mn toxicity. Low pH soils are also generally low in Ca, K, Na, and P; all essential major elements for plant growth. In lakes and marine situations acidic waters are uncommon as the waters are buffered. Calcium is again ameliorative of metal toxicities. The pH, redox, and valency state are critical in determining nutrient availability and metal speciation. Recent increases in the H+ ion content of precipitation have caused increased acidities of freshwater lakes in Scandinavia and eastern North America, which have depleted biota, including fish populations. PMID:31277

  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. Multicomponent analysis of mixed rare-earth metal ion solutions by the electronic tongue sensor system

    SciTech Connect

    Legin, A.; Kirsanov, D.; Rudnitskaya, A.; Rovny, S.; Logunov, M.

    2007-07-01

    Novel electrochemical sensors based on well-known extracting agents are developed. Sensors have shown high sensitivity towards a variety of rear earth metal ions in acidic media at pH=2. Multi-sensor system (electronic tongue) comprising newly developed sensors was successfully applied for the analysis of binary and ternary mixtures of Ce{sup 3+}, Nd{sup 3+}, Sm{sup 3+} and Gd{sup 3+} cations in different combinations. (authors)

  8. 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.

  9. 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.

  10. 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.

  11. Ion exchangers as adsorbents for removing metals from aquatic media.

    PubMed

    Khan, Meraj A; Bushra, Rani; Ahmad, Anees; Nabi, Syed A; Khan, Dilwar A; Akhtar, Arshia

    2014-02-01

    A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals. PMID:24292693

  12. Broad-beam, high current, metal ion implantation facility

    SciTech Connect

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

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs.

  13. Donnan dialysis of transition metal ions using anion exchange membrane modified with Xylenol Orange

    SciTech Connect

    Sawicka, B.; Brajter, K.; Trojanowicz, M.; Kado, B. )

    1991-01-01

    A chelating ion-exchange membrane was obtained by modification of a PTFE-based anion-exchange membrane with Xylenol Orange. Its utility for dialysis of Cu(II), Ni(II), Mn(II), and Zn(II) was investigated by using receiver solutions without and with iminodiacetate. 1,2-diaminocyclohexanetetraacetic acid, and tetraethylenepentamine. In comparison to commercial PTFE cation-exchange membranes, modified chelating membranes exhibit for the metal ions investigated a larger differentiation of retention in the membrane phase and transport-to-receiver solution depending on the modifier used and the composition of the receiver solution.

  14. [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.

  15. Adsorption of metal ions by carboxymethylchitin and carboxymethylchitosan hydrogels

    NASA Astrophysics Data System (ADS)

    Wasikiewicz, Jaroslaw M.; Nagasawa, Naotsugu; Tamada, Masao; Mitomo, Hiroshi; Yoshii, Fumio

    2005-07-01

    Radiation cross-linking of CM-chitin and CM-chitosan has been investigated. Such parameters of radiation cross-linking as gelation doses, cross-linking and degradation radiation yields and ratios of scission to cross-linking has been determined for both polymers. The absorption ability of various metal ions into EB-radiation cross-linked carboxymethylchitin and carboxymethylchitosan has been investigated. The highest adsorption of scandium and gold has been obtained for carboxymethylchitin (CMCht) and carboxymethylchitosan (CMChts), respectively. Kinetic studies showed that adsorption of most of the metal ions occur in a relatively short period of time (2 h). Detail investigation of adsorption of gold ions has been carried out for both hydrogels. The maximum uptake of Au cations, based on Langmuir equation was determined to be 37.59 for CM-chitosan and 11.86 for CM-chitin. Both hydrogels indicate favorable adsorption of gold cations.

  16. [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

  17. 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.

  18. 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.

  19. Metal ions affecting the pulmonary and cardiovascular systems.

    PubMed

    Corradi, Massimo; Mutti, Antonio

    2011-01-01

    Some metals, such as copper and manganese, are essential to life and play irreplaceable roles in, e.g., the functioning of important enzyme systems. Other metals are xenobiotics, i.e., they have no useful role in human physiology and, even worse, as in the case of lead, may be toxic even at trace levels of exposure. Even those metals that are essential, however, have the potential to turn harmful at very high levels of exposure, a reflection of a very basic tenet of toxicology--"the dose makes the poison." Toxic metal exposure may lead to serious risks to human health. As a result of the extensive use of toxic metals and their compounds in industry and consumer products, these agents have been widely disseminated in the environment. Because metals are not biodegradable, they can persist in the environment and produce a variety of adverse effects. Exposure to metals can lead to damage in a variety of organ systems and, in some cases, metals also have the potential to be carcinogenic. Even though the importance of metals as environmental health hazards is now widely appreciated, the specific mechanisms by which metals produce their adverse effects have yet to be fully elucidated. The unifying factor in determining toxicity and carcinogenicity for most metals is the generation of reactive oxygen and nitrogen species. Metal-mediated formation of free radicals causes various modifications to nucleic acids, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Whilst copper, chromium, and cobalt undergo redox-cycling reactions, for metals such as cadmium and nickel the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. This chapter attempts to show that the toxic effects of different metallic compounds may be manifested in the pulmonary and cardiovascular systems. The knowledge of health effects due to metal exposure is necessary for practising physicians, and should be assessed by inquiring

  20. 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.

  1. 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.

  2. Metal bridges to probe membrane ion channel structure and function.

    PubMed

    Linsdell, Paul

    2015-06-01

    Ion channels are integral membrane proteins that undergo important conformational changes as they open and close to control transmembrane flux of different ions. The molecular underpinnings of these dynamic conformational rearrangements are difficult to ascertain using current structural methods. Several functional approaches have been used to understand two- and three-dimensional dynamic structures of ion channels, based on the reactivity of the cysteine side-chain. Two-dimensional structural rearrangements, such as changes in the accessibility of different parts of the channel protein to the bulk solution on either side of the membrane, are used to define movements within the permeation pathway, such as those that open and close ion channel gates. Three-dimensional rearrangements – in which two different parts of the channel protein change their proximity during conformational changes – are probed by cross-linking or bridging together two cysteine side-chains. Particularly useful in this regard are so-called metal bridges formed when two or more cysteine side-chains form a high-affinity binding site for metal ions such as Cd2+ or Zn2+. This review describes the use of these different techniques for the study of ion channel dynamic structure and function, including a comprehensive review of the different kinds of conformational rearrangements that have been studied in different channel types via the identification of intra-molecular metal bridges. Factors that influence the affinities and conformational sensitivities of these metal bridges, as well as the kinds of structural inferences that can be drawn from these studies, are also discussed. PMID:26103632

  3. Metal bridges to probe membrane ion channel structure and function.

    PubMed

    Linsdell, Paul

    2015-06-01

    Ion channels are integral membrane proteins that undergo important conformational changes as they open and close to control transmembrane flux of different ions. The molecular underpinnings of these dynamic conformational rearrangements are difficult to ascertain using current structural methods. Several functional approaches have been used to understand two- and three-dimensional dynamic structures of ion channels, based on the reactivity of the cysteine side-chain. Two-dimensional structural rearrangements, such as changes in the accessibility of different parts of the channel protein to the bulk solution on either side of the membrane, are used to define movements within the permeation pathway, such as those that open and close ion channel gates. Three-dimensional rearrangements – in which two different parts of the channel protein change their proximity during conformational changes – are probed by cross-linking or bridging together two cysteine side-chains. Particularly useful in this regard are so-called metal bridges formed when two or more cysteine side-chains form a high-affinity binding site for metal ions such as Cd2+ or Zn2+. This review describes the use of these different techniques for the study of ion channel dynamic structure and function, including a comprehensive review of the different kinds of conformational rearrangements that have been studied in different channel types via the identification of intra-molecular metal bridges. Factors that influence the affinities and conformational sensitivities of these metal bridges, as well as the kinds of structural inferences that can be drawn from these studies, are also discussed.

  4. Metal cation dependence of interactions with amino acids: bond dissociation energies of Rb(+) and Cs(+) to the acidic amino acids and their amide derivatives.

    PubMed

    Armentrout, P B; Yang, Bo; Rodgers, M T

    2014-04-24

    Metal cation-amino acid interactions are key components controlling the secondary structure and biological function of proteins, enzymes, and macromolecular complexes comprising these species. Determination of pairwise interactions of alkali metal cations with amino acids provides a thermodynamic vocabulary that begins to quantify these fundamental processes. In the present work, we expand a systematic study of such interactions by examining rubidium and cesium cations binding with the acidic amino acids (AA), aspartic acid (Asp) and glutamic acid (Glu), and their amide derivatives, asparagine (Asn) and glutamine (Gln). These eight complexes are formed using electrospray ionization and their bond dissociation energies (BDEs) are determined experimentally using threshold collision-induced dissociation with xenon in a guided ion beam tandem mass spectrometer. Analyses of the energy-dependent cross sections include consideration of unimolecular decay rates, internal energy of the reactant ions, and multiple ion-neutral collisions. Quantum chemical calculations are conducted at the B3LYP, MP2(full), and M06 levels of theory using def2-TZVPPD basis sets, with results showing reasonable agreement with experiment. At 0 and 298 K, most levels of theory predict that the ground-state conformers for M(+)(Asp) and M(+)(Asn) involve tridentate binding of the metal cation to the backbone carbonyl, amino, and side-chain carbonyl groups, although tridentate binding to the carboxylic acid group and side-chain carbonyl is competitive for M(+)(Asn). For the two longer side-chain amino acids, Glu and Gln, multiple structures are competitive. A comparison of these results to those for the smaller alkali cations, Na(+) and K(+), provides insight into the trends in binding energies associated with the molecular polarizability and dipole moment of the side chain. For all four metal cations, the BDEs are inversely correlated with the size of the metal cation and follow the order Asp < Glu

  5. Actinide chelation: biodistribution and in vivo complex stability of the targeted metal ions.

    PubMed

    Kullgren, Birgitta; Jarvis, Erin E; An, Dahlia D; Abergel, Rebecca J

    2013-01-01

    Because of the continuing use of nuclear fuel sources and heightened threats of nuclear weapon use, the amount of produced and released radionuclides is increasing daily, as is the risk of larger human exposure to fission product actinides. A rodent model was used to follow the in vivo distribution of representative actinides, administered as free metal ions or complexed with chelating agents including diethylenetriamine pentaacetic acid (DTPA) and the hydroxypyridinonate ligands 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO). Different metabolic pathways for the different metal ions were evidenced, resulting in intricate ligand- and metal-dependent decorporation mechanisms. While the three studied chelators are known for their unrivaled actinide decorporation efficiency, the corresponding metal complexes may undergo in vivo decomposition and release metal ions in various biological pools. This study sets the basis to further explore the metabolism and in vivo coordination properties of internalized actinides for the future development of viable therapeutic chelating agents. PMID:22957518

  6. Actinide chelation: biodistribution and in vivo complex stability of the targeted metal ions.

    PubMed

    Kullgren, Birgitta; Jarvis, Erin E; An, Dahlia D; Abergel, Rebecca J

    2013-01-01

    Because of the continuing use of nuclear fuel sources and heightened threats of nuclear weapon use, the amount of produced and released radionuclides is increasing daily, as is the risk of larger human exposure to fission product actinides. A rodent model was used to follow the in vivo distribution of representative actinides, administered as free metal ions or complexed with chelating agents including diethylenetriamine pentaacetic acid (DTPA) and the hydroxypyridinonate ligands 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO). Different metabolic pathways for the different metal ions were evidenced, resulting in intricate ligand- and metal-dependent decorporation mechanisms. While the three studied chelators are known for their unrivaled actinide decorporation efficiency, the corresponding metal complexes may undergo in vivo decomposition and release metal ions in various biological pools. This study sets the basis to further explore the metabolism and in vivo coordination properties of internalized actinides for the future development of viable therapeutic chelating agents.

  7. pH-Dependent Metal Ion Toxicity Influences the Antibacterial Activity of Two Natural Mineral Mixtures

    PubMed Central

    Cunningham, Tanya M.; Koehl, Jennifer L.; Summers, Jack S.; Haydel, Shelley E.

    2010-01-01

    Background Recent studies have demonstrated that several mineral products sold for medicinal purposes demonstrate antimicrobial activity, but little is known about the physicochemical properties involved in antibacterial activity. Methodology/Principal Findings Using in vitro mineral suspension testing, we have identified two natural mineral mixtures, arbitrarily designated BY07 and CB07, with antibacterial activity against a broad-spectrum of bacterial pathogens. Mineral-derived aqueous leachates also exhibited antibacterial activity, revealing that chemical, not physical, mineral characteristics were responsible for the observed activity. The chemical properties essential for bactericidal activity against Escherichia coli were probed by testing antibacterial activity in the presence of metal chelators, the hydroxyl radical scavenger, thiourea, and varying pH levels. Chelation of the BY07 minerals with EDTA or desferrioxamine eliminated or reduced BY07 toxicity, respectively, suggesting a role of an acid-soluble metal species, particularly Fe3+ or other sequestered metal cations, in mineral toxicity. This conclusion was supported by NMR relaxation data, which indicated that BY07 and CB07 leachates contained higher concentrations of chemically accessible metal ions than leachates from non-bactericidal mineral samples. Conclusions/Significance We conclude that the acidic environment of the hydrated minerals significantly contributes to antibacterial activity by increasing the availability and toxicity of metal ions. These findings provide impetus for further investigation of the physiological effects of mineral products and their applications in complementary antibacterial therapies. PMID:20209160

  8. Blood metal ion levels are not a useful test for adverse reactions to metal debris

    PubMed Central

    Pahuta, M.; Smolders, J. M.; van Susante, J. L.; Peck, J.; Kim, P. R.

    2016-01-01

    Objectives Alarm over the reported high failure rates for metal-on-metal (MoM) hip implants as well as their potential for locally aggressive Adverse Reactions to Metal Debris (ARMDs) has prompted government agencies, internationally, to recommend the monitoring of patients with MoM hip implants. Some have advised that a blood ion level >7 µg/L indicates potential for ARMDs. We report a systematic review and meta-analysis of the performance of metal ion testing for ARMDs. Methods We searched MEDLINE and EMBASE to identify articles from which it was possible to reconstruct a 2 × 2 table. Two readers independently reviewed all articles and extracted data using explicit criteria. We computed a summary receiver operating curve using a Bayesian random-effects hierarchical model. Results Our literature search returned 575 unique articles; only six met inclusion criteria defined a priori. The discriminative capacity of ion tests was homogeneous across studies but that there was substantial cut-point heterogeneity. Our best estimate of the “true” area under curve (AUC) for metal ion testing is 0.615, with a 95% credible interval of 0.480 to 0.735, thus we can state that the probability that metal ion testing is actually clinically useful with an AUC ≥ 0.75 is 1.7%. Conclusion Metal ion levels are not useful as a screening test for identifying high risk patients because ion testing will either lead to a large burden of false positive patients, or otherwise marginally modify the pre-test probability. With the availability of more accurate non-invasive tests, we did not find any evidence for using blood ion levels to diagnose symptomatic patients. Cite this article: M. Pahuta, J. M. Smolders, J. L. van Susante, J. Peck, P. R. Kim, P. E. Beaule. Blood metal ion levels are not a useful test for adverse reactions to metal debris: a systematic review and meta-analysis. Bone Joint Res 2016;5:379–386. DOI: 10.1302/2046-3758.59.BJR-2016-0027.R1. PMID:27612918

  9. Recovery of boric acid from ion exchangers

    DOEpatents

    Pollock, Charles W.

    1976-01-01

    The recovery of boric acid from an anion exchange resin is improved by eluting the boric acid with an aqueous solution of ammonium bicarbonate. The boric acid can be readily purified and concentrated by distilling off the water and ammonium bicarbonate. This process is especially useful for the recovery of boric acid containing a high percentage of .sup.10 B which may be found in some nuclear reactor coolant solutions.

  10. Composition and process for separating cesium ions from an acidic aqueous solution also containing other ions

    DOEpatents

    Dietz, Mark L.; Horwitz, E. Philip; Bartsch, Richard A.; Barrans, Jr., Richard E.; Rausch, David

    1999-01-01

    A crown ether cesium ion extractant is disclosed as is its synthesis. The crown ether cesium ion extractant is useful for the selective purification of cesium ions from aqueous acidic media, and more particularly useful for the isolation of radioactive cesium-137 from nuclear waste streams. Processes for isolating cesium ions from aqueous acidic media using the crown ether cesium extractant are disclosed as are processes for recycling the crown ether cesium extractant and processes for recovering cesium from a crown ether cesium extractant solution.

  11. Composition and process for separating cesium ions from an acidic aqueous solution also containing other ions

    DOEpatents

    Dietz, M.L.; Horwitz, E.P.; Bartsch, R.A.; Barrans, R.E. Jr.; Rausch, D.

    1999-03-30

    A crown ether cesium ion extractant is disclosed as is its synthesis. The crown ether cesium ion extractant is useful for the selective purification of cesium ions from aqueous acidic media, and more particularly useful for the isolation of radioactive cesium-137 from nuclear waste streams. Processes for isolating cesium ions from aqueous acidic media using the crown ether cesium extractant are disclosed as are processes for recycling the crown ether cesium extractant and processes for recovering cesium from a crown ether cesium extractant solution. 4 figs.

  12. 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.

  13. Method for mobilization of hazardous metal ions in soils

    DOEpatents

    Dugan, P.R.; Pfister, R.M.

    1995-06-27

    A microbial process is revealed for removing heavy metals such as bismuth, cadmium, lead, thorium, uranium and other transuranics from soils and sediments. The method utilizes 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. 5 figs.

  14. Modification of Hydroxyapatite with Ion-Selective Complexants: 1-Hydroxyethane-1,1-diphosphonic Acid

    PubMed Central

    2015-01-01

    Hydroxyapatite (HAP) was modified with 1-hydroxyethane-1,1-diphosphonic acid (HEDP), and its effect on divalent metal ion binding was determined. HAP was synthesized from calcium hydroxide and phosphoric acid. After calcination, it was modified with HEDP, and the influence of time and temperature on the modification was investigated. HEDP incorporation increased as its initial solution concentration increased from 0.01 to 0.50 M. Unmodified and modified HAP were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and specific surface area analysis. Ca/P ratios, acid capacities, and phosphorus elemental analyses gave the effect of modification on composition and surface characteristics. A high reaction temperature produced new phosphonate bands at 993, 1082, and 1144 cm–1 that indicated the presence of HEDP. HAP modification at a high temperature–long reaction time had the highest HEDP loading and gave the sharpest XRD peaks. The emergence of new HAP–HEDP strands was observed in SEM images for treated samples while EDS showed high phosphorus contents in these strands. Modified HAP had a high acid capacity from the additional P–OH groups in HEDP. The P(O)OH groups maintain their ability to bind metal ions within the HAP matrix: contacting the modified HAP with 10–4 N nitrate solutions of five transition metal ions gives an affinity sequence of Pb(II) > Cd(II) > Zn(II) > Ni(II) > Cu(II). This result is comparable to that of commercially available di(2-ethylhexyl)phosphoric acid, a common solvent extractant, and the trend is consistent with the Misono softness parameter of metal ion polarizabilities. PMID:25678741

  15. 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.

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

    PubMed

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

    2011-01-01

    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.

  17. 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.

  18. 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.

  19. Designable architectures on nanoparticle surfaces: zirconium phosphate nanoplatelets as a platform for tetravalent metal and phosphonic acid assemblies.

    PubMed

    Mosby, Brian M; Goloby, Mark; Díaz, Agustín; Bakhmutov, Vladimir; Clearfield, Abraham

    2014-03-11

    Surface-functionalized zirconium phosphate (ZrP) nanoparticles were synthesized using a combination of ion exchange and self-assembly techniques. The surface of ZrP was used as a platform to deposit tetravalent metal ions by direct ion exchange with the protons of the surface phosphate groups. Subsequently, phosphonic acids were attached to the metal ion layer, effectively functionalizing the ZrP nanoparticles. Use of axially oriented bisphosphonic acids led to the ability to build layer-by-layer assemblies from the nanoparticle surface. Varying the metal ion and ligand used allowed designable architectures to be synthesized on the nanoparticle surface. X-ray powder diffraction, XPS, electron microprobe, solid-state NMR, FTIR, and TGA were used to characterize the synthesized materials.

  20. [Applications of metal ions and their complexes in medicine I].

    PubMed

    Nagy, László; Csintalan, Gabriella; Kálmán, Eszter; Sipos, Pál; Szvetnik, Attila

    2003-01-01

    The "inorganic medical chemistry" is a rapidly developing field with enormous potential for applications, which offers new possibilities to the pharmaceutical industry. For example, the titanocene dichloride is already in clinical use, and antimetastatic activity of a range of Ru(III) complexes is also well established. There are ways to minimize the toxicity of Gd(III) complexes and therefore they can be safely injected as MRI contrast agents. The so called "ligand design" allows paramagnetic ions to be targeted to specific organs. Such designed ligands also enable the targeting of radiodiagnostic (99mTc) and radiotherapeutic (186Re) isotopes. There is a significant progress in understanding the coordination chemistry and biochemistry of metal ion(s) containing complexes such as Au antiarthritic and Bi antiulcer drugs. Further, currently developing areas include Mn (SOD mimics), V (insulin mimics), Ru (NO scavengers), Ln-based photosensitizers, metal-targeted organic agents and the Fe overload. The expanding knowledge of the role of metals in biochemistry is expected to provide scope for the design of new drugs in many other areas too, for example neuropharmaceutical and antiaffective agents. Progress in coordination chemistry is strongly dependent on understanding not only the thermodynamics of reactions, but also the kinetics of metal complexes under biologically relevant conditions.

  1. 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.

  2. Heavy metals influence on ascorbic acid level

    NASA Astrophysics Data System (ADS)

    Kamaldinov, E. V.; Patrashkov, S. A.; Batenyeva, E. V.; Korotkevich, O. S.

    2003-05-01

    It is well known that heavy metals (HM) are extremely dangerous pollutants influencing to metabolism in animals' organisms. The vitamin C is one of the most important metabolites taking part in many biochemical processes. We studied the influence of main essential HM-Zn and Cu as well as the based supertoxical elements - Cd and Pd on ascorbic acid level in serum. The studies were carried out in Tulinskoe farm of Novosibirsk region. The objects of investigations were piglets (2 month after weaning) and 6-month pigs of Early Ripe Meat breed. The levels of HM in bristle were found by stripping voltammetric analysis using the TA-2 analyzer. Vitamin C content was determined by I.P. Kondrakhin (1985) method using 2,2-dipyridyl. The significant negative correlations between Pb, Cd content and vitamin C (-0.46 ± 0.18, -0.47 ± 0.19) in 6-month pigs were determined. The tendencies of negative correlation between all HM levels in hair and ascorbic acid level in plasma of piglets were revealed. Thus, the obtained correlations let us to suppose that all studied HM influence on 1-gulono-gamma-lactone oxidase and other vitamin C metabolism enzymes activity.

  3. Standard addition method for free acid determination in solutions with hydrolyzable ions

    SciTech Connect

    Baumann, E.W.

    1981-01-01

    The free acid content of solutions containing hydrolyzable ions has been determined potentiometrically by a standard addition method. Two increments of acid are added to the sample in a 1M potassium thiocyanate solution. The sample concentration is calculated by solution of three simultaneous Nernst equations. The method has been demonstrated for solutions containing Al/sup 3 +/, Cr/sup 3 +/, Fe/sup 3 +/, Ni/sup 2 +/, Th/sup 4 +/, or UO/sub 2//sup 2 +/ with a metal-to-acid ratio of < 2.5. The method is suitable for determination of 10 ..mu..moles acid in 10 mL total volume. The accuracy is verifiable by reasonable agreement of the Nerst slopes found in the presence and absence of hydrolyzable ions. The relative standard deviation is < 2.5 percent.

  4. Isothermal titration calorimetric procedure to determine protein-metal ion binding parameters in the presence of excess metal ion or chelator.

    PubMed

    Nielsen, Anders D; Fuglsang, Claus C; Westh, Peter

    2003-03-15

    Determination of binding parameters for metal ion binding to proteins usually requires preceding steps to remove protein-bound metal ions. Removal of bound metal ions from protein is often associated with decreased stability and inactivation. We present two simple isothermal titration calorimetric procedures that eliminate separate metal ion removal steps and directly monitor the exchange of metal ions between buffer, protein, and chelator. The concept is to add either excess chelator or metal ion to the protein under investigation and subsequently titrate with metal ion or chelator, respectively. It is thereby possible in the same experimental trial to obtain both chelator-metal ion and protein-metal ion binding parameters due to the different thermodynamic "fingerprints" of chelator and protein. The binding models and regression routines necessary to analyze the corresponding binding isotherms have been constructed. Verifications of the models have been done by titrations of mixtures of calcium chelators (BAPTA, HEDTA, and EGTA) and calcium ions and they were both able to account satisfactorily for the observed binding isotherms. Therefore, it was possible to determine stoichiometric and thermodynamic binding parameters. In addition, the concept has been tested on a recombinant alpha-amylase from Bacillus halmapalus where it proved to be a consistent procedure to obtain calcium binding parameters.

  5. Effect of Acid-Base Equilibrium on Absorption Spectra of Humic acid in the Presence of Copper Ions

    NASA Astrophysics Data System (ADS)

    Lavrik, N. L.; Mulloev, N. U.

    2014-03-01

    The reaction between humic acid (HA, sample IHSS) and a metal ion (Cu2+) that was manifested as absorption bands in the range 210-350 nm was recorded using absorption spectroscopy. The reaction was found to be more effective as the pH increased. These data were interpreted in the framework of generally accepted concepts about the influence of acid-base equilibrium on the dissociation of salts, according to which increasing the solution pH increases the concentration of HA anions. It was suggested that [HA-Cu2+] complexes formed.

  6. Solid State Structures of Alkali Metal Ion Complexes Formed by Low-Molecular-Weight Ligands of Biological Relevance.

    PubMed

    Aoki, Katsuyuki; Murayama, Kazutaka; Hu, Ning-Hai

    2016-01-01

    This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of alkali metal ion complexes containing low-molecular-weight ligands of biological relevance, mostly obtained from the Cambridge Structural Database (the CSD version 5.35 updated to February 2014). These ligands include (i) amino acids and small peptides, (ii) nucleic acid constituents (excluding quadruplexes and other oligonucleotides), (iii) simple carbohydrates, and (iv) naturally occurring antibiotic ionophores. For some representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described. PMID:26860299

  7. Metal ion release from new and recycled stainless steel brackets.

    PubMed

    Huang, Tsui-Hsien; Ding, Shinn-Jyh; Min, Yan; Kao, Chia-Tze

    2004-04-01

    As orthodontic appliances can corrode with time in the oral environment, the aim of this study was to compare the release of metal ions from new and recycled brackets immersed in buffers of different pH values over a 48 week period. To simulate commercial recycling, the stainless steel brackets were divided into two groups: new and recycled. The bases of the latter were coated with adhesive and the brackets were heat treated before being immersed in the test solution for 48 weeks. The release of nickel, chromium, iron, copper, cobalt and manganese ions was analysed by atomic absorption spectrophotometry. Differences were compared using one-way analysis of variance. The results showed that recycled brackets released more ions than new brackets (P < 0.05). Brackets immersed in solutions of pH 4 released more ions than those immersed in solutions of pH 7, and the total amount of ions released increased with time over the 48 week period (P < 0.05). This study demonstrates that both new and recycled brackets will corrode in the oral environment. To avoid clinical side-effects, metal brackets should be made more resistant to corrosion, and recycled brackets should not be used. PMID:15130040

  8. Application of sub-critical water technology for recovery of heavy metal ions from the wastes of Japanese scallop Patinopecten yessoensis.

    PubMed

    Tavakoli, Omid; Yoshida, Hiroyuki

    2008-07-15

    Sub-critical water (sub-CW) technology was used as a new technology with environmental and financial benefits for the recovery of harmful heavy metal ions Cd (II), Zn (II), Cu (II), Fe (II), Mn (II) and Ni (II) in the waste of Japanese scallop Patinopecten yessoensis. The metals are responsible for environmental problems owing to the large amount of the waste. This study proposes a new method using sub-CW treatment to recover the metal ions from scallop waste and simultaneously produce harmless and valuable materials. Reactions were conducted in a temperature range of 473-653 K and for reaction times of 1-60 min. After the sub-CW reaction, four phases existed: an oil phase, metal-soap phase, aqueous phase and solid residual. Some oil was hydrolyzed by the sub-CW reaction and converted to free fatty acids and glycerin. Free fatty acids reacted with metal ions and became metal-soap phase. Both the metal-soap phase and oil phase caught almost all metal ions at low and medium reaction temperatures (473-573 K) from original wastes, although the concentrations of the metal ions in the metal-soap phase were much higher than those in the oil phase. With increasing temperature, these two phases decomposed and the metal ions concentrated in solid residual (un-reacted waste). The binding mechanisms in the oil and metal-soap phases are discussed including the key functional groups involved. The maximum concentrations of metal ions in metal-soap phase were 7225 ppm (Fe), 862 ppm (Zn), and 800 ppm (Cd) at 573 K. The aqueous phase showed the lowest concentration of metal ions especially at temperatures above 550 K (~1.5 ppm).

  9. Biological treatment of heavy metals in acid mine drainage using sulfate reducing bioreactors.

    PubMed

    Sierra-Alvarez, R; Karri, S; Freeman, S; Field, J A

    2006-01-01

    The uncontrolled release of acid mine drainage (AMD) from abandoned mines and tailing piles threatens water resources in many sites worldwide. AMD introduces elevated concentrations of sulfate ions and dissolved heavy metals as well as high acidity levels to groundwater and receiving surface water. Anaerobic biological processes relying on the activity of sulfate reducing bacteria are being considered for the treatment of AMD and other heavy metal containing effluents. Biogenic sulfides form insoluble complexes with heavy metals resulting in their precipitation. The objective of this study was to investigate the remediation of AMD in sulfate reducing bioreactors inoculated with anaerobic granular sludge and fed with an influent containing ethanol. Biological treatment of an acidic (pH 4.0) synthetic AMD containing high concentrations of heavy metals (100 mg Cu(2+)l(-1); 10 mg Ni(2+)l(-1), 10 mg Zn(2+)l(-1)) increased the effluent pH level to 7.0-7.2 and resulted in metal removal efficiencies exceeding 99.2%. The highest metal precipitation rates attained for Cu, Ni and Zn averaged 92.5, 14.6 and 15.8 mg metal l(-1) of reactor d(-1). The results of this work demonstrate that an ethanol-fed sulfidogenic reactor was highly effective to remove heavy metal contamination and neutralized the acidity of the synthetic wastewater.

  10. Fulvic acid-sulfide ion competition for mercury ion binding in the Florida everglades

    USGS Publications Warehouse

    Reddy, M.M.; Aiken, G.R.

    2001-01-01

    Negatively charged functional groups of fulvic acid compete with inorganic sulfide ion for mercury ion binding. This competition is evaluated here by using a discrete site-electrostatic model to calculate mercury solution speciation in the presence of fulvic acid. Model calculated species distributions are used to estimate a mercury-fulvic acid apparent binding constant to quantify fulvic acid and sulfide ion competition for dissolved inorganic mercury (Hg(II)) ion binding. Speciation calculations done with PHREEQC, modified to use the estimated mercury-fulvic acid apparent binding constant, suggest that mercury-fulvic acid and mercury-sulfide complex concentrations are equivalent for very low sulfide ion concentrations (about 10-11 M) in Everglades' surface water. Where measurable total sulfide concentration (about 10-7 M or greater) is present in Everglades' surface water, mercury-sulfide complexes should dominate dissolved inorganic mercury solution speciation. In the absence of sulfide ion (for example, in oxygenated Everglades' surface water), fulvic acid binding should dominate Everglades' dissolved inorganic mercury speciation.

  11. 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

  12. 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

  13. 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.

  14. 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.}

  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. 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

  17. MRI probes for sensing biologically relevant metal ions.

    PubMed

    Bonnet, Célia S; Tóth, Eva

    2010-03-01

    Given the important role of metal ions in fundamental biological processes, the visualization of their concentration in living animals by repeatable, noninvasive imaging techniques, such as MRI, would be highly desirable. A large number of metal-responsive MRI contrast agents, the majority based on Gd(3+) complexes, have been reported in recent years. The contrast-enhancing properties (relaxivity) of a Gd(3+) complex can be most conveniently modulated by interaction with the sensed metal cation via changes in the number of water molecules bound directly to Gd(3+) or changes in the size of the complex, which represent the two major strategies to develop metal sensitive MRI probes. Here, we survey paramagnetic lanthanide complexes involving Gd(3+) agents and paramagnetic chemical exchange saturation transfer probes designed to detect the most important endogenous metal ions: calcium, zinc, iron and copper. Future work will likely focus on extending applications of these agents to living animals, as well as on exploring new ways of creating molecular MRI probes in order to meet requirements such as higher specificity or lower detection limits.

  18. Acid Hydrolysis of Trioxalatocobaltate (III) Ion

    ERIC Educational Resources Information Center

    Wiggans, P. W.

    1975-01-01

    Describes an investigation involving acid hydrolysis and using both volumetric and kinetic techniques. Presents examples of the determination of the rate constant and its variation with temperature. (GS)

  19. 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.

  20. 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.

  1. 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.

  2. 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...

  3. Leaching of metals from steel samples in peracetic acid

    NASA Astrophysics Data System (ADS)

    Yabutani, Tomoki; Nakamura, Takamasa; Takayabagi, Toshio

    2015-03-01

    In this paper, leaching behavior of metallic species from steel samples in peracetic acid was investigated. We compared the leaching efficiency between peracetic acid and acetic acid to estimate the role of peroxo functional group for the leaching. As a result, peracetic acid enhanced the leaching ability of metallic species from the high speed steel and the alloy steel samples. MoO3, Mo, MO2C, W, WO3, VC and MnO2 were effectively leached by peracetic acid, while the stainless steel had a high resistance against corrosion by peracetic acid.

  4. Chloride ion-aided self-assembly of pseudoclathrochelate metal tris-pyrazoloximates.

    PubMed

    Varzatskii, Oleg A; Penkova, Larysa V; Kats, Svitlana V; Dolganov, Alexander V; Vologzhanina, Anna V; Pavlov, Alexander A; Novikov, Valentin V; Bogomyakov, Artem S; Nemykin, Victor N; Voloshin, Yan Z

    2014-03-17

    Chloride ion-aided one-pot template self-assembly of a mixed pyrazoloxime ligand with phenylboronic acid on a corresponding metal(II) ion as a matrix afforded the first boron-capped zinc, cobalt, iron, and manganese pseudoclathrochelate tris-pyrazoloximates. The presence of a pseudocross-linking hydrogen-bonded chloride ion is critical for their formation, as the same chloride-capped complexes were isolated even in the presence of large excesses of bromide and iodide ions. As revealed by X-ray diffraction, all complexes are capped with a chloride ion via three N-H···Cl hydrogen bonds that stabilize their pseudomacrobicyclic frameworks. The MN6 coordination polyhedra possess a distorted trigonal prismatic geometry, with the distortion angles φ between their nonequivalent N3 bases of approximately 0°. Temperature dependences of the effective magnetic moment for the paramagnetic complexes showed the encapsulated metal(II) ions to be in a high-spin state in the temperature range of 2-300 K. In the case of the iron(II) pseudoclathrochelate, density functional theory (DFT) and time-dependent DFT calculations were used to assess its spin state as well as the (57)Fe Mössbauer and UV-vis-NIR parameters. Cyclic voltammetry studies performed for these pseudomacrobicyclic complexes showed them to undergo irreversible or quasi-reversible metal-localized oxidations and reductions. As no changes are observed in the presence of a substantial excess of bromide ion, no anion-exchange reaction occurs, and thus the pseudoclathrochelates have a high affinity toward chloride anions in solution. PMID:24559424

  5. Bifunctional phenyl monophosphonic/sulfonic acid ion exchange resin and process for using the same

    DOEpatents

    Alexandratos, Spiro; Shelley, Christopher A.; Horwitz, E. Philip; Chiarizia, Renato

    2001-01-01

    A cross-linked water-insoluble ion exchange resin comprised of polymerized monomers having a phenyl ring is disclosed. A contemplated resin contains (i) polymerized phenyl ring-containing monomers having a phosphonic acid ligand linked to the phenyl ring, (ii) about 2 to about 5 millimoles per gram (mmol/g) of phosphorus as phosphonic acid ligands, and (iii) a sufficient amount of a sulfonic acid ligand such that the ratio of mmol/g of phosphonic acid to mmol/g sulfonic acid is up to 3:1. A process for removing polyvalent metal cations from aqueous solution, and a process for removing iron(III) cations from acidic copper(II) cation-containing solutions that utilize the contemplated resin or other resins are disclosed.

  6. Bifunctional phenyl monophosphonic/sulfonic acid ion exchange resin and process for using the same

    DOEpatents

    Alexandratos, Spiro; Shelley, Christopher A.; Horwitz, E. Philip; Chiarizia, Renato; Gula, Michael J.; Xue, Sui; Harvey, James T.

    2002-01-01

    A cross-linked water-insoluble ion exchange resin comprised of polymerized monomers having a phenyl ring is disclosed. A contemplated resin contains (i) polymerized phenyl ring-containing monomers having a phosphonic acid ligand linked to the phenyl ring, (ii) about 2 to about 5 millimoles per gram (mmol/g) of phosphorus as phosphonic acid ligands, and (iii) a sufficient amount of a sulfonic acid ligand such that the ratio of mmol/g of phosphonic acid to mmol/g sulfonic acid is up to 3:1. A process for removing polyvalent metal cations from aqueous solution, and a process for removing iron(III) cations from acidic copper(II) cation-containing solutions that utilize the contemplated resin or other resins are disclosed.

  7. Ion trap collision-induced dissociation of locked nucleic acids.

    PubMed

    Huang, Teng-yi; Kharlamova, Anastasia; McLuckey, Scott A

    2010-01-01

    Gas-phase dissociation of model locked nucleic acid (LNA) oligonucleotides and functional LNA-DNA chimeras have been investigated as a function of precursor ion charge state using ion trap collision-induced dissociation (CID). For the model LNA 5 and 8 mer, containing all four LNA monomers in the sequence, cleavage of all backbone bonds, generating a/w-, b/x-, c/y-, and d/z-ions, was observed with no significant preference at lower charge states. Base loss ions, except loss of thymine, from the cleavage of N-glycosidic bonds were also present. In general, complete sequence coverage was achieved in all charge states. For the two LNA-DNA chimeras, however, dramatic differences in the relative contributions of the competing dissociation channels were observed among different precursor ion charge states. At lower charge states, sequence information limited to the a-Base/w-fragment ions from cleavage of the 3'C-O bond of DNA nucleotides, except thymidine (dT), was acquired from CID of both the LNA gapmer and mixmer ions. On the other hand, extensive fragmentation from various dissociation channels was observed from post-ion/ion ion trap CID of the higher charge state ions of both LNA-DNA chimeras. This report demonstrates that tandem mass spectrometry is effective in the sequence characterization of LNA oligonucleotides and LNA-DNA chimeric therapeutics.

  8. The influence of metal ions on malic enzyme activity and lipid synthesis in Aspergillus niger.

    PubMed

    Jernejc, Katarina; Legisa, Matic

    2002-12-17

    In the presence of copper significant induction of citric acid overflow was observed, while concomitantly lower levels of total lipids were detected in the cells. Its effect was more obvious in a medium with magnesium as sole divalent metal ions, while in a medium with magnesium and manganese the addition of copper had a less pronounced effect. Since the malic enzyme was recognised as a supplier of reducing power in the form of reduced nicotinamide adenine dinucleotide phosphate for lipid biosynthesis, its kinetic parameters with regard to different concentrations of metal ions were investigated. Some inhibition was found with Fe(2+) and Zn(2+), while Cu(2+) ions in a concentration of 0.1 mM completely abolished malic enzyme activity. The same metal ions proportionally reduced the levels of total lipids in Aspergillus niger cells. A strong competitive inhibition of the enzyme by Cu(2+) was observed. It seemed that copper competes with Mg(2+) and Mn(2+) for the same binding site on the protein.

  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.

  10. 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

  11. Hydrogels Triggered by Metal Ions as Precursors of Network CuS for DNA Detection.

    PubMed

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

    2015-08-17

    The gelation behavior of lithocholate (LC(-) ) with different metal ions in water was investigated. The microstructures of hydrogels were determined to be three-dimensional (3D) networks of fibrous aggregates. The formation of fibrils was speculated to be mainly driven by the coordination between carboxylate of LC(-) and metal ions, accompanied by the assistance of noncovalent interactions such as electrostatic and hydrophobic interactions. The hydrogels, which can maintain the mechanical strength at higher temperature, exhibit thermal stability. Their gelation capability was enhanced with the increase in acidity. The hydrogels of LC(-) and Cu(2+) mixtures served as the precursors for producing network nanostructures of CuS nanoparticles. These new CuS networks exhibit high fluorescence quenching ability and can act as an effective fluorescent sensing platform for ssDNA detection.

  12. Removal of heavy metal ions from wastewater by chemically modified plant wastes as adsorbents: a review.

    PubMed

    Wan Ngah, W S; Hanafiah, M A K M

    2008-07-01

    The application of low-cost adsorbents obtained from plant wastes as a replacement for costly conventional methods of removing heavy metal ions from wastewater has been reviewed. It is well known that cellulosic waste materials can be obtained and employed as cheap adsorbents and their performance to remove heavy metal ions can be affected upon chemical treatment. In general, chemically modified plant wastes exhibit higher adsorption capacities than unmodified forms. Numerous chemicals have been used for modifications which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. In this review, an extensive list of plant wastes as adsorbents including rice husks, spent grain, sawdust, sugarcane bagasse, fruit wastes, weeds and others has been compiled. Some of the treated adsorbents show good adsorption capacities for Cd, Cu, Pb, Zn and Ni.

  13. Coordination properties of hydralazine Schiff base. Synthesis and equilibrium studies of some metal ion complexes

    NASA Astrophysics Data System (ADS)

    Shoukry, Azza A.; Shoukry, Mohamed M.

    2008-08-01

    In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and 1H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies.

  14. Transition metal ion capture using functional mesoporous carbon made with 1,10-phenanthroline

    SciTech Connect

    Chouyyok, Wilaiwan; Yantasee, Wassana; Shin, Yongsoon; Grudzien, Rafal M.; Fryxell, Glen E.

    2009-11-01

    Functional mesoporous carbon has been built using 1,10-phenanthroline as the fundamental building block, resulting in a nanoporous, high surface area sorbent capable of selectively binding transition metal ions. This material had a specific surface area of 870 m2/g, an average pore size of about 30Å, and contained as much as 8.2 weight percent N. Under acidic conditions, where the 1,10-phenanthroline ligand is protonated, this material was found to be an effective anion exchange material for transition metal anions like PdCl4-2 and H2VO4-1. 1,10-phenanthroline functionalized mesoporous carbon (“Phen-FMC”) was found to have a high affinity for Cu(II), even down to a pH of 1. At pHs above 5, Phen-FMC was found to bind a variety of transition metal cations (e.g. Co(II), Ni(II), Zn(II), etc.) from filtered ground water, river water and seawater. Phen-FMC displayed rapid sorption kinetics with Co(II) in filtered river water, reaching equilibrium in less than an hour, and easily lowering the [Co(II)] to sub-ppb levels. Phen-FMC was found to be more effective for transition metal ion capture than ion exchange resin or activated carbon.

  15. Transition metal ion capture using functional mesoporous carbon made with 1,10-phenanthroline☆

    PubMed Central

    Chouyyok, Wilaiwan; Yantasee, Wassana; Shin, Yongsoon; Grudzien, Rafal M.; Fryxell, Glen E.

    2012-01-01

    Functional mesoporous carbon has been built using 1,10-phenanthroline as the fundamental building block, resulting in a nanoporous, high surface area sorbent capable of selectively binding transition metal ions. This material had a specific surface area of 870 m2/g, an average pore size of about 30 Å, and contained as much as 8.2 wt% N. Under acidic conditions, where the 1,10-phenanthroline ligand is protonated, this material was found to be an effective anion exchange material for transition metal anions like PdCl42- and H2VO41-. 1,10-Phenanthroline functionalized mesoporous carbon (“Phen-FMC”) was found to have a high affinity for Cu(II), even down to a pH of 1. At pHs above 5, Phen-FMC was found to bind a variety of transition metal cations (e.g. Co(II), Ni(II), Zn(II), etc.) from filtered ground water, river water and seawater. Phen-FMC displayed rapid sorption kinetics with Co(II) in filtered river water, reaching equilibrium in less than an hour, and easily lowering the [Co(II)] to sub-ppb levels. Phen-FMC was found to be more effective for transition metal ion capture than ion-exchange resin or activated carbon. PMID:23762013

  16. Shale oil from the LLNL pilot retort: Metal ions as markers for water and dust

    SciTech Connect

    Coburn, T.T.; Duewer, T.I.; King, K.J.; Baldwin, D.E.; Cena, R.J.

    1993-12-31

    A metal ion found primarily in one of the three phases (oil, water, or dust) can serve as a marker for that phase. Emulsified water contains most of the magnesium detected in a shale oil. Extraction with saturated salt solution removes most of that Mg. The Mg content of retort water and the percentage of water in the oil (by ASTM D-4006) provides a good estimate of an oil`s Mg content. Mineral matter elements with poorly water soluble carbonates (or oxides) at pH 8 (calcium, for example) serve as markers for dust. When the water is separated from the main and light oil fractions before adding the heavy fraction containing dust, a much drier oil can be obtained. However, when done in this way, a powder containing Ca and Si remains in the oil; it cannot be completely removed even by filtering through a 0.24-{mu} frit. Iron, and certain other transition metal ions, is quite oil soluble. Extraction with dilute nitric acid to remove basic amines reduces the Fe content of shale oil. Unlike carboxylate- complexed metal ions in crude oils, the iron in shale oil does not extract efficiently into an aqueous EDTA solution (pH 5.9). Distillation of shale oil leaves most of the iron and other metals behind in the vacuum residum. Shale oil corrodes the hottest condenser`s steel interior; this is the chief source of iron in the oil.

  17. Combined cytotoxicity and genotoxicity of a marine toxin and seafood contaminant metal ions (chromium and cadmium).

    PubMed

    Souid-Mensi, Ghada; Moukha, Serge; Maaroufi, Khira; Creppy, Edmond E

    2008-02-01

    Algal bloom with consequent production of marine toxins contaminating bivalves is increasing in costal regions worldwide because of sea water quality worsening. Contamination of seafood by diarrheic shellfish poisoning toxins (DSP) together with metals is frequently reported, a phenomenon not fully explained yet. In this context, metal ions were assayed in clams collected from the banned area of Boughrara, Tunisia, contaminated by Gymnodinium and other algae such as Dinophysis sp, accumulated by these bivalves. The presence of toxic metals ions such as Chromium (Cr) and Cadmium (Cd) in meat, shells, and water released by the clams prompted us to experiment in Caco-2 intestinal cell line toxic effects of these heavy metals ions in combination with okadaic acid, one DSP present in clams to assess the potential global toxicity. Cr and Cd produce additive effects in (i) reactive oxygen species production, (ii) cytotoxicity as assessed by the mitochondrial activity testing method (MTT test), and (iii) DNA lesions evaluated by agarose gel electrophoresis and acridine orange staining. Exaggerated DNA fragmentation is observed, suggesting an overloading of repair capacity of Caco-2 cells. The apoptosis suggested by a DNA fragment sizing (180-200 bp) in agarose gel and mechanisms underlying these additive effects in Caco-2 cells still need to be more comprehensively explained.

  18. 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.

  19. Bioleaching of valuable metals from spent lithium-ion mobile phone batteries using Aspergillus niger

    NASA Astrophysics Data System (ADS)

    Horeh, N. Bahaloo; Mousavi, S. M.; Shojaosadati, S. A.

    2016-07-01

    In this paper, a bio-hydrometallurgical route based on fungal activity of Aspergillus niger was evaluated for the detoxification and recovery of Cu, Li, Mn, Al, Co and Ni metals from spent lithium-ion phone mobile batteries under various conditions (one-step, two-step and spent medium bioleaching). The maximum recovery efficiency of 100% for Cu, 95% for Li, 70% for Mn, 65% for Al, 45% for Co, and 38% for Ni was obtained at a pulp density of 1% in spent medium bioleaching. The HPLC results indicated that citric acid in comparison with other detected organic acids (gluconic, oxalic and malic acid) had an important role in the effectiveness of bioleaching using A. niger. The results of FTIR, XRD and FE-SEM analysis of battery powder before and after bioleaching process confirmed that the fungal activities were quite effective. In addition, bioleaching achieved higher removal efficiency for heavy metals than the chemical leaching. This research demonstrated the great potential of bio-hydrometallurgical route to recover heavy metals from spent lithium-ion mobile phone batteries.

  20. Ion-beam-induced deoxyribose nucleic acid transfer

    NASA Astrophysics Data System (ADS)

    Anuntalabhochai, S.; Chandej, R.; Phanchaisri, B.; Yu, L. D.; Vilaithong, T.; Brown, I. G.

    2001-04-01

    We report our observations of the interaction of energetic ions with bacterial cells, inducing direct deoxyribose nucleic acid (DNA) transfer into Escherichia coli (E. coli). Argon- and nitrogen-ion beams were used to bombard the bacteria E. coli in a vacuum with energy of 26 keV and fluence in the range 0.5-4×1015 ions/cm2. Three DNA plasmids, pGEM2, pGEM-T easy, and pGFP, carrying different marker genes, were subsequently transferred (separately) into the appropriately ion-bombarded bacteria and successfully expressed. The results of this study indicate that ion beams with an energy such that the ion range is approximately equal to the cell envelope thickness, at a certain range of fluence, are able to generate pathways for macromolecule transfer through the envelope without irreversible damage.

  1. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm. PMID:26748867

  2. Ion-exchange behavior of alkali metals on treated carbons

    SciTech Connect

    Mohiuddin, G.; Hata, W.Y.; Tolan, J.S.

    1983-01-01

    The ion-exchange behavior of trace quantities of the alkali-metal ions sodium and cesium, on activated carbon impregnated with zirconium phosphate (referred to here as ZrP), was studied. Impregnated carbon had twice as much ion-exchange activity as unimpregnated, oxidized carbon, and 10 times as much as commercial activated carbons. The distribution coefficient of sodium increased with increasing pH; the distribution coefficient of cesium decreased with increasing pH. Sodium and cesium were separated with an electrolytic solution of 0.1 M HCl. Preliminary studies indicated that 0.2 M potassium and cesium can also be separated. Distribution coefficients of the supported ZrP were determined by the elution technique and agreed within 20% of the values for pure ZrP calculated from the literature.

  3. 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.

  4. Cation–Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting

    PubMed Central

    Gebala, Magdalena; Giambasu, George M.; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M.; Herschlag, Daniel

    2016-01-01

    The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that “count” the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation–anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation–anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4–P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new

  5. Cation-Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting.

    PubMed

    Gebala, Magdalena; Giambaşu, George M; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M; Herschlag, Daniel

    2015-11-25

    The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that "count" the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation-anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation-anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4-P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new results leads to

  6. 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.

  7. 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.

  8. Plasmonics for the study of metal ion-protein interactions.

    PubMed

    Grasso, Giuseppe; Spoto, Giuseppe

    2013-02-01

    The study of metal-protein interactions is an expanding field of research investigated by bioinorganic chemists as it has wide applications in biological systems. Very recently, it has been reported that it is possible to study metal-protein interactions by immobilizing biomolecules on metal surfaces and applying experimental approaches based on plasmonics which have usually been used to investigate protein-protein interactions. This is possible because the electronic structure of metals generates plasmons whose properties can be exploited to obtain information from biomolecules that interact not only with other molecules but also with ions in solution. One major challenge of such approaches is to immobilize the protein to be studied on a metal surface with preserved native structure. This review reports and discusses all the works that deal with such an expanding new field of application of plasmonics with specific attention to surface plasmon resonance, highlighting the advantages and drawbacks of such approaches in comparison with other experimental techniques traditionally used to study metal-protein interactions.

  9. 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

  10. 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

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

    2015-12-15

    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 Mg(2+). 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 Mg(2+) from Ca(2+). 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.

  11. 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.

  12. Charged Amino Acids (R83, E567, D617, E625, R669, and K678) of CusA Are Required for Metal Ion Transport in the Cus Efflux System

    SciTech Connect

    Su, Chih-Chia; Long, Feng; Lei, Hsiang-Ting; Reddy Bolla, Jani; Do, Sylvia V.; Rajashankar, Kanagalaghatta R.; Yu, Edward W.

    2012-10-23

    Gram-negative bacteria expel various toxic chemicals via tripartite efflux pumps belonging to the resistance-nodulation-cell division superfamily. These pumps span both the inner and outer membranes of the cell. The three components of these tripartite systems are an inner-membrane, substrate-binding transporter (or pump); a periplasmic membrane fusion protein (or adaptor); and an outer-membrane-anchored channel. These three efflux proteins interact in the periplasmic space to form the three-part complexes. We previously presented the crystal structures of both the inner-membrane transporter CusA and membrane fusion protein CusB of the CusCBA tripartite efflux system from Escherichia coli. We also described the co-crystal structure of the CusBA adaptor-transporter, revealing that the trimeric CusA efflux pump assembles with six CusB protein molecules to form the complex CusB{sub 6}-CusA{sub 3}. We here report three different conformers of the crystal structures of CusBA-Cu(I), suggesting a mechanism on how Cu(I) binding initiates a sequence of conformational transitions in the transport cycle. Genetic analysis and transport assays indicate that charged residues, in addition to the methionine pairs and clusters, are essential for extruding metal ions out of the cell.

  13. Metal-ion Absorption in Conductively Evaporating Clouds

    NASA Astrophysics Data System (ADS)

    Gnat, Orly; Sternberg, Amiel; McKee, Christopher F.

    2010-08-01

    We present computations of the ionization structure and metal-absorption properties of thermally conductive interface layers that surround evaporating warm spherical clouds embedded in a hot medium. We rely on the analytical steady-state formalism of Dalton and Balbus to calculate the temperature profile in the evaporating gas, and we explicitly solve the time-dependent ionization equations for H, He, C, N, O, Si, and S in the conductive interface. We include photoionization by an external field. We estimate how departures from equilibrium ionization affect the resonance-line cooling efficiencies in the evaporating gas, and determine the conditions for which radiative losses may be neglected in the solution for the evaporation dynamics and temperature profile. Our results indicate that nonequilibrium cooling significantly increases the value of the saturation parameter σ0 at which radiative losses begin to affect the flow dynamics. As applications, we calculate the ion fractions and projected column densities arising in the evaporating layers surrounding dwarf-galaxy-scale objects that are also photoionized by metagalactic radiation. We compare our results to the UV metal-absorption column densities observed in local highly ionized metal absorbers, located in the Galactic corona or intergalactic medium. Conductive interfaces significantly enhance the formation of high ions such as C3+, N4+, and O5+ relative to purely photoionized clouds, especially for clouds embedded in a high-pressure corona. However, the enhanced columns are still too low to account for the O VI columns (~1014 cm-2) observed in the local high-velocity metal-ion absorbers. We find that column densities larger than ~1013 cm-2 cannot be produced in evaporating clouds. Our results do support the conclusion of Savage and Lehner that absorption due to evaporating O VI likely occurs in the local interstellar medium, with characteristic columns of ~1013 cm-2.

  14. Probing the metal ion selectivity in methionine aminopeptidase via changes in the luminescence properties of the enzyme bound europium ion.

    PubMed

    Sule, Nitesh; Singh, Raushan K; Zhao, Pinjing; Srivastava, D K

    2012-01-01

    We report herein, for the first time, that Europium ion (Eu(3+)) binds to the "apo" form of Escherichia coli methionine aminopeptidase (EcMetAP), and such binding results in the activation of the enzyme as well as enhancement in the luminescence intensity of the metal ion. Due to competitive displacement of the enzyme-bound Eu(3+) by different metal ions, we could determine the binding affinities of both "activating" and "non-activating" metal ions for the enzyme via fluorescence spectroscopy. The experimental data revealed that among all metal ions, Fe(2+) exhibited the highest binding affinity for the enzyme, supporting the notion that it serves as the physiological metal ion for the enzyme. However, the enzyme-metal binding data did not adhere to the Irving-William series. On accounting for the binding affinity vis a vis the catalytic efficiency of the enzyme for different metal ions, it appears evident that that the "coordination states" and the relative softness" of metal ions are the major determinants in facilitating the EcMetAP catalyzed reaction.

  15. Interaction of some metals between marine-origin humic acids and aqueous solutions

    SciTech Connect

    Huljev, D.J.

    1986-08-01

    The interaction of metal ions (carrier-free form) in aquatic medium with humic acids is a complicated process depending on the properties of humic acids (elementary, chemical, and trace element composition), metals studied (valence, charge, chemical form, concentration), and medium used (pH, ionic strength). The use of radionuclides was found to be very suitable for a rapid and precise determination of the distribution coefficient K/sub d/ (ratio of the concentration of a certain trace metal association with a gram of humic acid over the concentration of the same trace metal per milliliter of solution) of the investigated system. Isolated humic acids from offshore sediments from the North Adriatic (Lim channel, near Rovinj, Yugoslavia) were characterized according to their elementary composition, the amount of products of hydrolysis, and the trace elements bound. All experiments were carried out between pH 3 and 5. It was found that conditions usually present at the site where humic acid interacts with metal ions (anaerobic conditions, H/sub 2/S) in brackish (21% S) and standard seawater (38% S) are determined in the pH range 3 to 5. The results of the pick-up (uptake) and replacement (release) experiments are presented as a distribution coefficient (K/sub d/), as a function of contact time. Processes of pick-up and replacement of a number of metals under various physicochemical conditions were investigated and special attention was paid to the influence of salinity. With the increase in NaCl concentration and pH in the system, the fixation of ruthenium, zinc, cobalt, and mercury by humic acids decreased.

  16. Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect

    NASA Astrophysics Data System (ADS)

    Samsonowicz, M.; Regulska, E.; Lewandowski, W.

    2011-11-01

    The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions [1]. The vibrational FT-IR (in KBr and ATR techniques) and 1H and 13C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg → Ba were compared with series of univalent metal Li → Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.

  17. [Metal ions restrain the elimination of 4-tert-octylphenol by delta-MnO2].

    PubMed

    Li, Fei-Li; Mou, Hua-Qian

    2013-06-01

    The effect of metal ions on elimination of 4-t-OP by synthetic delta-MnO2 suspension at pH 4.0 was studied. Experiments indicated that the removal of 4-t-OP by delta-MnO2 achieved 100% at reaction time of 150 min. However, the removal of 4-t-OP by delta-MnO2 was restrained when metal ions were added, and the higher concentration of metal ion was, the stronger the inhibition produced. Additionally, there were apparent differences among the inhibitory effect of the tested metal ions. Firstly, Pb2+ and Mn2+ had the strongest effect at pH 4.0, followed by the transition metal ions, then the alkaline earth ions, while the alkali metal ions had little influence on the removal of 4-t-OP by delta-MnO2. Also comparing the adsorption results of metal ions by delta-MnO2, Pb2+ showed the greatest attraction with delta-MnO2, and among the other metal ions, transition metal ions were adsorbed a little more strongly on delta-MnO2 than alkaline earth metal ions. Consequences showed that the inhibitory effects of metal ions were due to their occupying reactive sites on delta-MnO2 surface, which competed with 4-t-OP. Moreover, the dissimilar suppressions were contributed by the different adsorption capacities, surface structure change of MnO2 and the difference of free metal ion percentage in solution as well as metal ions radii.

  18. 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

  19. Spectrophotometric determination and removal of unchelated europium ions from solutions containing Eu-diethylenetriaminepentaacetic acid chelate-peptide conjugates.

    PubMed

    Elshan, N G R Dayan; Patek, Renata; Vagner, Josef; Mash, Eugene A

    2014-11-01

    Europium chelates conjugated with peptide ligands are routinely used as probes for conducting in vitro binding experiments. The presence of unchelated Eu ions in these formulations gives high background luminescence and can lead to poor results in binding assays. In our experience, the reported methods for purification of these probes do not achieve adequate removal of unchelated metal ions in a reliable manner. In this work, a xylenol orange-based assay for the quantification of unchelated metal ions was streamlined and used to determine levels of metal ion contamination as well as the success of metal ion removal on attempted purification. We compared the use of Empore chelating disks and Chelex 100 resin for the selective removal of unchelated Eu ions from several Eu-diethylenetriaminepentaacetic acid chelate-peptide conjugates. Both purification methods gave complete and selective removal of the contaminant metal ions. However, Empore chelating disks were found to give much higher recoveries of the probes under the conditions used. Related to the issue of probe recovery, we also describe a significantly more efficient method for the synthesis of one such probe using Rink amide AM resin in place of Tentagel S resin.

  20. Constructing Chemical Concepts through a Study of Metals and Metal Ions: Guided Inquiry Experiments for General Chemistry

    NASA Astrophysics Data System (ADS)

    Lamba, Ram S.; Sharma, Shiva; Lloyd, Baird W.

    1997-09-01

    This paper describes a set of inquiry-based experiments designed to help students develop an understanding of basic chemical concepts within the framework of studying the properties and reactivity of metals and metal ions. The students perform these experiments before the concepts are discussed in class, with the emphasize on the construction of meaning from observation, measurement, and data analysis. The set includes: Are All Pennies the Same?, which introduces students to the differences between extensive and intensive quantities. How Much is Enough?, examines the quantitative aspects of the reaction between metals and hydrogen ions leading to the concept of the mole and stoichiometric calculations. How Much is Too Much?, which identifies and distinguishes between limiting reagents, excess reagents, spectator ions and reactant ions. What is an Active Metal?, provides the observations needed to sort common metals into an activity series and How Active are the Active Metals?, allows students to develop a quantitative model of metal activity.

  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. 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.

  3. 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.

  4. Trivalent metal ions based on inorganic compounds with in vitro inhibitory activity of matrix metalloproteinase 13.

    PubMed

    Wen, Hanyu; Qin, Yuan; Zhong, Weilong; Li, Cong; Liu, Xiang; Shen, Yehua

    2016-10-01

    Collagenase-3 (MMP-13) inhibitors have attracted considerable attention in recent years and have been developed as a therapeutic target for a variety of diseases, including cancer. Matrix metalloproteinases (MMPs) can be inhibited by a multitude of compounds, including hydroxamic acids. Studies have shown that materials and compounds containing trivalent metal ions, particularly potassium hexacyanoferrate (III) (K3[Fe(CN)6]), exhibit cdMMP-13 inhibitory potential with a half maximal inhibitory concentration (IC50) of 1.3μM. The target protein was obtained by refolding the recombinant histidine-tagged cdMMP-13 using size exclusion chromatography (SEC). The secondary structures of the refolded cdMMP-13 with or without metal ions were further analyzed via circular dichroism and the results indicate that upon binding with metal ions, an altered structure with increased domain stability was obtained. Furthermore, isothermal titration calorimetry (ITC) experiments demonstrated that K3[Fe(CN)6]is able to bind to MMP-13 and endothelial cell tube formation tests provide further evidence for this interaction to exhibit anti-angiogenesis potential. To the best of our knowledge, no previous report of an inorganic compound featuring a MMP-13 inhibitory activity has ever been reported in the literature. Our results demonstrate that K3[Fe(CN)6] is useful as a new effective and specific inhibitor for cdMMP-13 which may be of great potential for future drug screening applications. PMID:27542739

  5. Ion-exchange aspects of toxic metal uptake by Indian mustard.

    PubMed

    Crist, Ray H; Martin, J Robert; Crist, DeLanson R

    2004-01-01

    Uptake of lead (Pb), copper (Cu), zinc (Zn), and cadmium (Cd) as +2 ions by excised roots of Indian mustard was demonstrated to be an ion-exchange process with existing Ca or protons released to the solution. This initial reaction at the root-aqueous interface is important in the uptake of these toxic metals from contaminated soil. Ethylene diamine tetraacetic acid (EDTA)-amended soil for phytoremediation has Pb in anionic form as [Pb-EDTA]2-, which was not taken up by excised roots. In nonliving B. juncea, Pb2+ was translocated from a solution through a cut stem to petiole and leaves much more quickly than anionic [Pb-EDTA]2-. However, in living plants [Pb-EDTA]2- was more quickly translocated from a solution through roots and petiole to leaves than Pb2+. The final amount of uptake on roots of the living plants was the same for both forms of Pb. The present results are important toward understanding the mechanism of phytoremediation of toxic metal-contaminated soil for two reasons: 1) the initial process, uptake of metal ions by roots, was shown to occur by cation exchange and 2) since [Pb-EDTA]2- was not sorbed by excised roots, other factors such as transpiration and active transport are important in applications using EDTA-amended soils contaminated by Pb. PMID:15224777

  6. Mechanism of adsorption of hard and soft metal ions to Saccharomyces cerevisiae and influence of hard and soft anions.

    PubMed Central

    Avery, S V; Tobin, J M

    1993-01-01

    The applicability of the hard-and-soft principle of acids and bases in predicting metal adsorption characteristics in a biological context was investigated for metabolism-independent uptake of the metal ions Sr2+, Mn2+, Zn2+, Cu2+, Cd2+, and Tl+ by Saccharomyces cerevisiae. Metal adsorption increased with external metal concentration (5 to 50 microM), although some saturation of uptake of the harder ions examined, Sr2+, Mn2+, and Zn2+, was evident at the higher metal concentrations. Cation displacement experiments indicated that, with the exception of Tl+, relative covalent bonding (H+ displacement) of the metals was greater at low metal concentrations, while weaker electrostatic interactions (Mg2+ plus Ca2+ displacement) became increasingly important at higher concentrations. These results were correlated with curved Scatchard and reciprocal Langmuir plots of metal uptake data. Saturation of covalent binding sites was most marked for the hard metals, and consequently, although no relationship between metal hardness and ionic/covalent bonding ratios was evident at 10 microM metal, at 50 microM the ratio was generally higher for harder metals. Increasing inhibition of metal uptake at increasing external anion concentrations was partially attributed to the formation of metal-anion complexes. Inhibitory effects of the hard anion SO42(-) were most marked for uptake of the hard metals Sr2+ and Mn2+, whereas greater relative effects on adsorption of the softer cations Cu2+ and Cd2+ were correlated with complexation by the soft anion S2O32(-). Inhibition of uptake of the borderline metal Zn2+ by SO42(-) and that by S2O32(-) were approximately equal.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8215359

  7. Recent progress in fluorescent and colorimetric chemosensors for detection of precious metal ions (silver, gold and platinum ions).

    PubMed

    Zhang, Jun Feng; Zhou, Ying; Yoon, Juyoung; Kim, Jong Seung

    2011-07-01

    Due to the wide range of applications and biological significance, the development of optical probes for silver, gold and platinum ions has been an active research area in the past few years. This tutorial review focuses on the recent contributions concerning the fluorescent or colorimetric sensors for these metal ions, and is organized according to their structural classifications (for Ag(+) detection) and unique mechanisms between the sensors and metal ions (for Au(3+) and Pt(2+) detection).

  8. 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

  9. 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

  10. Inner-shell photodetachment of transition metal negative ions

    NASA Astrophysics Data System (ADS)

    Dumitriu, Ileana

    This thesis focuses on the study of inner-shell photodetachment of transition metal negative ions, specifically Fe- and Ru- . Experimental investigations have been performed with the aim of gaining new insights into the physics of negative atomic ions and providing valuable absolute cross section data for astrophysics. The experiments were performed using the X-ray radiation from the Advanced Light Source, Lawrence Berkeley National Laboratory, and the merged-beam technique for photoion spectroscopy. Negative ions are a special class of atomic systems very different from neutral atoms and positive ions. The fundamental physics of the interaction of transition metal negative ions with photons is interesting but difficult to analyze in detail because the angular momentum coupling generates a large number of possible terms resulting from the open d shell. Our work reports on the first inner-shell photodetachment studies and absolute cross section measurements for Fe- and Ru -. In the case of Fe-, an important astrophysical abundant element, the inner-shell photodetachment cross section was obtained by measuring the Fe+ and Fe2+ ion production over the photon energy range of 48--72 eV. The absolute cross sections for the production of Fe+ and Fe2+ were measured at four photon energies. Strong shape resonances due to the 3p→3d photoexcitation were measured above the 3p detachment threshold. The production of Ru+, Ru2+, and Ru3+ from Ru- was measured over 30--90 eV photon energy range The absolute photodetachment cross sections of Ru - ([Kr] 4d75s 2) leading to Ru+, Ru2+, and Ru 3+ ion production were measured at three photon energies. Resonance effects were observed due to interference between transitions of the 4 p-electrons to the quasi-bound 4p54d85s 2 states and the 4d→epsilonf continuum. The role of many-particle effects, intershell interaction, and polarization seems much more significant in Ru- than in Fe- photodetachment.

  11. 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)

  12. 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.

  13. Another look at equatorial metallic ions in the F region

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Reese, N.

    1989-01-01

    An extensive survey is made of the equatorial occurrences of the Fe+ ion as detected by the ion mass spectrometer on the Atmospheric Explorer E. The longest time period (4 years) data base available for the study of the equatorial metallic ion distributions is considered, as well as Fe+ concentrations exceeding 10, 30, and 100 per cubic cm. The number of occurrences in the F region are most frequent at the dayside dip equator. Diurnally, the events are not appreciable in the F region until a few hours after dawn, reaching a maximum near noon followed by a secondary maximum in the afternoon. Near and after dusk the Fe+ ions extended on the average to higher altitudes than during the day and became less and less frequent from midnight to dawn. Seasonally, the distributions between 200 and 300 km are skewed away from the dip equator during the day with the maximum frequency of occurrence north (south) of the dip equator during a period centered on the December (June) solstice.

  14. Ion-induced spike effects on metal surfaces.

    SciTech Connect

    Donnelly, S. E.; Birtcher, R. C.; Materials Science Division; Univ. of Salford

    1999-01-01

    The effects of single Xe ion impacts on the surfaces of Au, Ag, In and Pb have been studied using in-situ transmission electron microscopy. Individual ion impacts produce surface craters with associated expelled material. The cratering efficiency scales with the density of the irradiated metal. Calculation indicates that, when collision cascades occur near surfaces (within about 5 nm) with energy densities sufficient to cause local melting, craters will occur. Crater formation occurs as a result of the explosive outflow of material from the hot molten core of the cascade. This would appear to indicate that, although the number of atoms in a spike is small and its duration short, it is reasonable to use macroscopic concepts such as vibrational temperature, melting and flow to describe spike effects.

  15. High-resolution mass spectrometer for liquid metal ion sources

    SciTech Connect

    Wortmann, Martin; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.; Meijer, Jan

    2013-09-15

    Recently, a mass spectrometer for liquid metal ion sources (LMIS) has been built and set into operation. This device uses an E×B-filter as mass dispersive element and provides sufficient resolution to analyse the emission of clusters from LMIS to much higher mass ranges (>2000 amu) than commercially available mass filters for focused ion beam systems. It has also been shown that for small masses the composition of clusters from different isotopes can be resolved. Furthermore, a rather high fluence of monodisperse clusters in the range of 10{sup 6}–10{sup 7} clusters/s can be achieved with this setup. This makes it a promising tool for the preparation of mass selected clusters. In this contribution, theoretical considerations as well as technical details and the results of first measurements are presented.

  16. High-resolution mass spectrometer for liquid metal ion sources.

    PubMed

    Wortmann, Martin; Ludwig, Arne; Meijer, Jan; Reuter, Dirk; Wieck, Andreas D

    2013-09-01

    Recently, a mass spectrometer for liquid metal ion sources (LMIS) has been built and set into operation. This device uses an E × B-filter as mass dispersive element and provides sufficient resolution to analyse the emission of clusters from LMIS to much higher mass ranges (>2000 amu) than commercially available mass filters for focused ion beam systems. It has also been shown that for small masses the composition of clusters from different isotopes can be resolved. Furthermore, a rather high fluence of monodisperse clusters in the range of 10(6)-10(7) clusters/s can be achieved with this setup. This makes it a promising tool for the preparation of mass selected clusters. In this contribution, theoretical considerations as well as technical details and the results of first measurements are presented.

  17. 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.

  18. Controlled charge exchange between alkaline earth metals and their ions

    NASA Astrophysics Data System (ADS)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be<-->9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  19. 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.

  20. How Hydrogen Bonds Affect the Growth of Reverse Micelles around Coordinating Metal Ions.

    PubMed

    Qiao, Baofu; Demars, Thomas; Olvera de la Cruz, Monica; Ellis, Ross J

    2014-04-17

    Extensive research on hydrogen bonds (H-bonds) have illustrated their critical role in various biological, chemical and physical processes. Given that existing studies are predominantly performed in aqueous conditions, how H-bonds affect both the structure and function of aggregates in organic phase is poorly understood. Herein, we investigate the role of H-bonds on the hierarchical structure of an aggregating amphiphile-oil solution containing a coordinating metal complex by means of atomistic molecular dynamics simulations and X-ray techniques. For the first time, we show that H-bonds not only stabilize the metal complex in the hydrophobic environment by coordinating between the Eu(NO3)3 outer-sphere and aggregating amphiphiles, but also affect the growth of such reverse micellar aggregates. The formation of swollen, elongated reverse micelles elevates the extraction of metal ions with increased H-bonds under acidic condition. These new insights into H-bonds are of broad interest to nanosynthesis and biological applications, in addition to metal ion separations.

  1. Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer.

    PubMed

    Choe, Cholho; Yang, Ling; Lv, Zhanao; Mo, Wanling; Chen, Zhuqi; Li, Guangxin; Yin, Guochuan

    2015-05-21

    Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(II) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(II) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al(3+) to the manganese(II) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(II) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, Mn(III)-(μ-O)2-Mn(IV). The presence of a Lewis acid like Al(3+) causes the dissociation of this diamond Mn(III)-(μ-O)2-Mn(IV) core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.

  2. Electrolyte materials containing highly dissociated metal ion salts

    SciTech Connect

    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.

  3. Electrolyte materials containing highly dissociated metal ion salts

    SciTech Connect

    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.

  4. 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.

  5. Thermochemistry and Reactivity of Transition Metal Cluster Ions

    NASA Astrophysics Data System (ADS)

    Armentrout, P. B.; Griffin, J. B.; Conceićão, J.

    Reactions of transition metal cluster cations with several small molecules have been examined using guided ion beam mass spectrometry. This technique allows the kinetic energy dependence of the reactions to be measured, thereby allowing thermodynamic information to be extracted. Reactions of iron, chromium, and vanadium clusters with D2, O2, and CO2 are described. Reactions with D2 are endothermic and yield only two types of products. Oxidation of metal clusters by O2 proceeds is very efficient, proceeding at the collision limit, and forms many different products. The CO2 systems exhibit interesting dynamics that appears to be related to interactions of two surfaces of different spin. Bond energies for cluster monodeuterides, monoxides, and dioxides are derived from these studies. The deuteride bond energies appear to be sensitive to the cluster geometry while little variation in oxide bond energies is observed as a function of cluster size. Comparison of these cluster bond energies to bulk phase values finds similar thermochemistry.

  6. 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(+).

  7. Evaluation of a low-cost adsorbent for removal of toxic metal ions from wastewater of an electroplating factory.

    PubMed

    Sousa, Francisco W; Sousa, Marcelo James; Oliveira, Isadora R N; Oliveira, André G; Cavalcante, Rivelino M; Fechine, Pierre B A; Neto, Vicente O S; de Keukeleire, Denis; Nascimento, Ronaldo F

    2009-08-01

    In this study, sugar cane residue or bagasse was used for removal of toxic metal ions from wastewater of an electroplating factory located in northeast Brazil. Prior acid treatment increased the adsorption efficacies in batch wise experiments. The microstructure of the material before and after the treatment was investigated by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Column operations showed that removals of Cu(2+), Ni(2+) and Zn(2+) from wastewater (in the absence of cyanide) were 95.5%, 96.3.0%, and 97.1%, respectively. Regeneration of the adsorbent obtained in acid indicated that the efficiencies decreased only after the fourth cycle of re-use. Acid-treated sugar cane bagasse can be considered a viable alternative to common methods to remove toxic metal ions from aqueous effluents of electroplating industries.

  8. Negative ion photoelectron spectroscopy of metal clusters, metal-organic clusters, metal oxides, and metal-doped silicon clusters

    NASA Astrophysics Data System (ADS)

    Zheng, Weijun

    The techniques of time-of-flight mass spectrometry and negative ion photoelectron spectroscopy were utilized to study metal clusters (Mgn -, Znn-, Can -, Mnn-, CuAln -, LiAln-, and NmSn n-), metal-organic complexes (Tin(benzene) m-, Fn(benzene)m- , Nin(benzene)m-), metal oxides(AuO-, PtO-, TaOn -, HfO2-, and MnnO -), and metal-doped semiconductor clusters (CrSin -, GdmSin- and HoSi n-). The study of magnesium and zinc cluster anions shows that they have magic numbers at size 9, 19 and 34, and the closures and reopenings of the s-p band gap are related to the mass spectra magic numbers. The evolution of electronic structure in Can clusters resembles that of Mgn - and Znn- with band gap closure and reopening. However, the electronic structures Can- clusters are more complicated and the magic numbers are different from those of Mgn- and Znn -. That might due to the involvement of calcium's empty d orbitals. In Mn clusters, a dramatic change of electronic structure was observed at Mn5-. The transition of metallic and magnetic properties is strongly related to the s-d hybridization. The photoelectron study of LiAln- is consistent with theoretical predictions, which described LiAl13 as alkali-halide-like ionic entity, Li+(Al13)-. The results of CuAln- show that copper atom might occupy interior position in these clusters. The results of Nam Snn- implied that Na4Sn 4 and NaSn5- could be described as (Na +)4Sn44- and (Na +)Sn52-, respectively. The formation of these species indicates the existence of Zintl phase structure in the gas phase. Tin(Bz)n+1- clusters have multiple-decker sandwich structures with each titanium atom located between two parallel benzene rings. The structures of Fen(Bz)m - and Nin(Bz)m- are characterized with a metal cluster core caged by benzene molecules. The information for the electronic states of PtO, AuO, and TaOn (n = 1--3) were obtained from the photoelectron spectra of their corresponding negative ions. The coincidence between electron

  9. Separation of ions in acidic solution by capillary electrophoresis

    SciTech Connect

    Thornton, M.

    1997-10-08

    Capillary electrophoresis (CE) is an effective method for separating ionic species according to differences in their electrophoretic mobilities. CE separations of amino acids by direct detection are difficult due to their similar electrophoretic mobilities and low absorbances. However, native amino acids can be separated by CE as cations at a low pH by adding an alkanesulfonic acid to the electrolyte carrier which imparts selectivity to the system. Derivatization is unnecessary when direct UV detection is used at 185 nm. Simultaneous speciation of metal cations such as vanadium (IV) and vanadium (V) can easily be performed without complexation prior to analysis. An indirect UV detection scheme for acidic conditions was also developed using guanidine as the background carrier electrolyte (BCE) for the indirect detection of metal cations. Three chapters have been removed for separate processing. This report contains introductory material, references, and general conclusions. 80 refs.

  10. Removal and recovery of metal ions from process and waste streams using polymer filtration

    SciTech Connect

    Jarvinen, G.D.; Smith, B.F.; Robison, T.W.; Kraus, K.M.; Thompson, J.A.

    1999-06-13

    Polymer Filtration (PF) is an innovative, selective metal removal technology. Chelating, water-soluble polymers are used to selectively bind the desired metal ions and ultrafiltration is used to concentrate the polymer-metal complex producing a permeate with low levels of the targeted metal ion. When applied to the treatment of industrial metal-bearing aqueous process streams, the permeate water can often be reused within the process and the metal ions reclaimed. This technology is applicable to many types of industrial aqueous streams with widely varying chemistries. Application of PF to aqueous streams from nuclear materials processing and electroplating operations will be described.

  11. Selective recovery of valuable metals from spent Li-ion batteries using solvent-impregnated resins.

    PubMed

    Guo, Fuqiang; Nishihama, Syouhei; Yoshizuka, Kazuharu

    2013-01-01

    Selective recovery of valuable metals (Cu(2+), Co(2+) and Li(+)) from leachate of spent lithium-ion (Li-ion) batteries was investigated in acidic chloride media using solvent impregnated resins (SIRs). An SIR containing bis(2-ethylhexyl) phosphoric acid (D2EHPA) had high selectivity for Fe(3+) and Al(3+), with an order of selectivity Fe(3+) > Al(3+) > Cu(2+) > Co(2+). Fe(3+) and Al(3+) could be removed from synthetic leachate by precipitation, followed by column adsorption with the SIR containing D2EHPA. The synthetic leachate was then applied to chromatography for selective recovery of Cu(2+), Co(2+) and Li(+). The solution was first fed upward to a column packed with an SIR containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A) for selective separation of Cu(2+), followed by upward feed to another column packed with an SIR comprising PC-88A and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) for selective recovery of Co(2+). Finally, a column packed with a synergistic SIR containing both 1-phenyl-1,3-tetradecanedione (C11phbetaDK) and tri-n-octylphosphine oxide (TOPO) was used for selective recovery of Li(+). A process flowsheet is proposed for selective recovery of Cu(2+), Co(2+) and Li(+) using several SIRs. This process was found to be simple and efficient for selective recovery of valuable metals from leachate of spent Li-ion batteries. Pure copper, cobalt and lithium products were obtained, with high elution yields. PMID:24191463

  12. Selective recovery of valuable metals from spent Li-ion batteries using solvent-impregnated resins.

    PubMed

    Guo, Fuqiang; Nishihama, Syouhei; Yoshizuka, Kazuharu

    2013-01-01

    Selective recovery of valuable metals (Cu(2+), Co(2+) and Li(+)) from leachate of spent lithium-ion (Li-ion) batteries was investigated in acidic chloride media using solvent impregnated resins (SIRs). An SIR containing bis(2-ethylhexyl) phosphoric acid (D2EHPA) had high selectivity for Fe(3+) and Al(3+), with an order of selectivity Fe(3+) > Al(3+) > Cu(2+) > Co(2+). Fe(3+) and Al(3+) could be removed from synthetic leachate by precipitation, followed by column adsorption with the SIR containing D2EHPA. The synthetic leachate was then applied to chromatography for selective recovery of Cu(2+), Co(2+) and Li(+). The solution was first fed upward to a column packed with an SIR containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A) for selective separation of Cu(2+), followed by upward feed to another column packed with an SIR comprising PC-88A and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) for selective recovery of Co(2+). Finally, a column packed with a synergistic SIR containing both 1-phenyl-1,3-tetradecanedione (C11phbetaDK) and tri-n-octylphosphine oxide (TOPO) was used for selective recovery of Li(+). A process flowsheet is proposed for selective recovery of Cu(2+), Co(2+) and Li(+) using several SIRs. This process was found to be simple and efficient for selective recovery of valuable metals from leachate of spent Li-ion batteries. Pure copper, cobalt and lithium products were obtained, with high elution yields.

  13. Chemical noise reduction via mass spectrometry and ion/ion charge inversion: amino acids.

    PubMed

    Hassell, Kerry M; LeBlanc, Yves C; McLuckey, Scott A

    2011-05-01

    Charge inversion ion/ion reactions can provide a significant reduction in chemical noise associated with mass spectra derived from complex mixtures for species composed of both acidic and basic sites, provided the ions derived from the matrix largely undergo neutralization. Amino acids constitute an important class of amphoteric compounds that undergo relatively efficient charge inversion. Precipitated plasma constitutes a relatively complex biological matrix that yields detectable signals at essentially every mass-to-charge value over a wide range. This chemical noise can be dramatically reduced using multiply charged reagent ions that can invert the charge of species amenable to the transfer of multiple charges upon a single interaction and by detecting product ions of opposite polarity. The principle is illustrated here with amino acids present in precipitated plasma subjected to ionization in the positive mode, reaction with anions derived from negative nanoelectrospray ionization of poly (amido amine) dendrimer generation 3.5, and mass analysis in the negative ion mode. PMID:21456599

  14. Moving metal ions through ferritin-protein nanocages from three-fold pores to catalytic sites.

    PubMed

    Tosha, Takehiko; Ng, Ho-Leung; Bhattasali, Onita; Alber, Tom; Theil, Elizabeth C

    2010-10-20

    Ferritin nanocages synthesize ferric oxide minerals, containing hundreds to thousands of Fe(III) diferric oxo/hydroxo complexes, by reactions of Fe(II) ions with O(2) at multiple di-iron catalytic centers. Ferric-oxy multimers, tetramers, and/or larger mineral nuclei form during postcatalytic transit through the protein cage, and mineral accretion occurs in the central cavity. We determined how Fe(II) substrates can access catalytic sites using frog M ferritins, active and inactivated by ligand substitution, crystallized with 2.0 M Mg(II) ± 0.1 M Co(II) for Co(II)-selective sites. Co(II) inhibited Fe(II) oxidation. High-resolution (<1.5 Å) crystal structures show (1) a line of metal ions, 15 Å long, which penetrates the cage and defines ion channels and internal pores to the nanocavity that link external pores to the cage interior, (2) metal ions near negatively charged residues at the channel exits and along the inner cavity surface that model Fe(II) transit to active sites, and (3) alternate side-chain conformations, absent in ferritins with catalysis eliminated by amino acid substitution, which support current models of protein dynamics and explain changes in Fe-Fe distances observed during catalysis. The new structural data identify a ∼27-Å path Fe(II) ions can follow through ferritin entry channels between external pores and the central cavity and along the cavity surface to the active sites where mineral synthesis begins. This "bucket brigade" for Fe(II) ion access to the ferritin catalytic sites not only increases understanding of biological nanomineral synthesis but also reveals unexpected design principles for protein cage-based catalysts and nanomaterials.

  15. Acid Strength and Bifunctional Catalytic Behavior of Alloys Comprised of Noble Metals and Oxophilic Metal Promoters

    SciTech Connect

    Hibbitts, David D.; Tan, Qiaohua; Neurock, Matthew

    2014-06-01

    The promotion of metal catalysts with partially oxidized oxophilic MOx species, such as ReOx-promoted Rh, has been demonstrated to produce Brønsted acid sites that can promote hydrogenolysis of oxygenate intermediates such as those found in biomass-derived species. A wide variety of alloy compositions and structures are examined in this work to investigate strongly acidic promoters by using DFT-calculated deprotonation energies (DPE) as a measure of acid strength. Sites with the highest acid strength had DPE less than 1100 kJ mol-1, similar to DPE values of heteropolyacids or acid-containing zeolites, and were found on alloys composed of an oxophilic metal (such as Re or W) with a noble metal (such as Rh or Pt). NH3 adsorbs more strongly to sites with increasing acid strength and the activation barriers for acid-catalyzed ring opening of a furan ring decrease with increasing acid strength, which was also shown to be stronger for OH acid sites bound to multiple oxophilic metal atoms in a three-fold configuration rather than OH sites adsorbed in an atop configuration on one oxophilic metal, indicating that small MOx clusters may yield sites with the highest acid strength.

  16. 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

  17. Local Dynamics of Acid- and Ion-containing Copolymer Melts

    NASA Astrophysics Data System (ADS)

    Winey, Karen; Middleton, Robert; Tarver, Jacob; Tyagi, Madhusudan; Soles, Christopher; Frischknecht, Amalie

    Interest in acid- and ion-containing polymers arises in part from applications as single-ion conductors for selectively transporting a counter ion for battery applications. Structurally, the low dielectric constant of organic polymers and strong ionic interactions leads to ionic aggregation. Here the polymer backbone motion was investigated through quasi-elastic neutron scattering measurements (QENS) and compared with fully atomistic molecular dynamic simulations of precise poly(ethylene-acrylic acid) copolymers and their ionomers (pxAA-y%Li). The effect of carbon spacer length (x =9, 15, 21) between the acid groups and the degree of neutralization (y) with Li on PE backbone dynamics were considered. Systematic slowing in chain dynamics were observed with increasing neutralization where polymer dynamics appear constrained due to anchoring effects. Simulations provide complementary viewpoints indicating a gradient in chain dynamics as a distance away from acid groups. These results indicate that the addition of pendant acid groups inhibit typical PE backbone motion and the neutralized forms strongly suppress the fraction of mobile PE chain.

  18. 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.

  19. Genome Sequence Analysis of the Naphthenic Acid Degrading and Metal Resistant Bacterium Cupriavidus gilardii CR3

    PubMed Central

    Xiao, Jingfa; Hao, Lirui; Crowley, David E.; Zhang, Zhewen; Yu, Jun; Huang, Ning; Huo, Mingxin; Wu, Jiayan

    2015-01-01

    Cupriavidus sp. are generally heavy metal tolerant bacteria with the ability to degrade a variety of aromatic hydrocarbon compounds, although the degradation pathways and substrate versatilities remain largely unknown. Here we studied the bacterium Cupriavidus gilardii strain CR3, which was isolated from a natural asphalt deposit, and which was shown to utilize naphthenic acids as a sole carbon source. Genome sequencing of C. gilardii CR3 was carried out to elucidate possible mechanisms for the naphthenic acid biodegradation. The genome of C. gilardii CR3 was composed of two circular chromosomes chr1 and chr2 of respectively 3,539,530 bp and 2,039,213 bp in size. The genome for strain CR3 encoded 4,502 putative protein-coding genes, 59 tRNA genes, and many other non-coding genes. Many genes were associated with xenobiotic biodegradation and metal resistance functions. Pathway prediction for degradation of cyclohexanecarboxylic acid, a representative naphthenic acid, suggested that naphthenic acid undergoes initial ring-cleavage, after which the ring fission products can be degraded via several plausible degradation pathways including a mechanism similar to that used for fatty acid oxidation. The final metabolic products of these pathways are unstable or volatile compounds that were not toxic to CR3. Strain CR3 was also shown to have tolerance to at least 10 heavy metals, which was mainly achieved by self-detoxification through ion efflux, metal-complexation and metal-reduction, and a powerful DNA self-repair mechanism. Our genomic analysis suggests that CR3 is well adapted to survive the harsh environment in natural asphalts containing naphthenic acids and high concentrations of heavy metals. PMID:26301592

  20. Genome Sequence Analysis of the Naphthenic Acid Degrading and Metal Resistant Bacterium Cupriavidus gilardii CR3.

    PubMed

    Wang, Xiaoyu; Chen, Meili; Xiao, Jingfa; Hao, Lirui; Crowley, David E; Zhang, Zhewen; Yu, Jun; Huang, Ning; Huo, Mingxin; Wu, Jiayan

    2015-01-01

    Cupriavidus sp. are generally heavy metal tolerant bacteria with the ability to degrade a variety of aromatic hydrocarbon compounds, although the degradation pathways and substrate versatilities remain largely unknown. Here we studied the bacterium Cupriavidus gilardii strain CR3, which was isolated from a natural asphalt deposit, and which was shown to utilize naphthenic acids as a sole carbon source. Genome sequencing of C. gilardii CR3 was carried out to elucidate possible mechanisms for the naphthenic acid biodegradation. The genome of C. gilardii CR3 was composed of two circular chromosomes chr1 and chr2 of respectively 3,539,530 bp and 2,039,213 bp in size. The genome for strain CR3 encoded 4,502 putative protein-coding genes, 59 tRNA genes, and many other non-coding genes. Many genes were associated with xenobiotic biodegradation and metal resistance functions. Pathway prediction for degradation of cyclohexanecarboxylic acid, a representative naphthenic acid, suggested that naphthenic acid undergoes initial ring-cleavage, after which the ring fission products can be degraded via several plausible degradation pathways including a mechanism similar to that used for fatty acid oxidation. The final metabolic products of these pathways are unstable or volatile compounds that were not toxic to CR3. Strain CR3 was also shown to have tolerance to at least 10 heavy metals, which was mainly achieved by self-detoxification through ion efflux, metal-complexation and metal-reduction, and a powerful DNA self-repair mechanism. Our genomic analysis suggests that CR3 is well adapted to survive the harsh environment in natural asphalts containing naphthenic acids and high concentrations of heavy metals. PMID:26301592

  1. 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.

  2. Diverse structures of metal-organic frameworks based on different metal ions: luminescence and gas adsorption properties.

    PubMed

    Zhang, Chuan-Lei; Qin, Ling; Shi, Zhen-Zhen; Zheng, He-Gen

    2015-03-01

    Four coordination polymers with different metal ions have been synthesized based on a rigid linear pyridine and a flexible V-shaped dicarboxylate ligand (L = 4,4'-(2,5-dimethoxy-1,4-phenylene)dipyridine; H2OBA = 4,4'-oxydibenzoic acid): {[Co(L)(OBA)]·2H2O}n (1), [Zn(L)(OBA)·2H2O]n (2), {[Ni(L)(OBA)]·DMF·H2O}n (3), [Cd(L)(OBA)]·DMF·H2O}n (4). The reaction conditions are similar except for the metal ions for complexes 1-4. Complexes 1 and 2 present a 3D unprecedented hxg-d-4-Cccm net, but 3 and 4 are 4-connected sql nets with a point symbol {4(4)·6(2)}. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. The UV-visible spectra, fluorescence, and gas adsorption properties of the compounds were also explored. PMID:25631059

  3. 68Zn isotope exchange experiments reveal an unusual kinetic lability of the metal ions in the di-zinc form of IMP-1 metallo-beta-lactamase.

    PubMed

    Siemann, Stefan; Badiei, Hamid R; Karanassios, Vassili; Viswanatha, Thammaiah; Dmitrienko, Gary I

    2006-02-01

    The apparently paradoxical behaviour of facile exchange (kinetic lability) of tightly bound (thermodynamic stability) zinc ions in the enzyme IMP-1 metallo-beta-lactamase with Zn-68 and cadmium ions, as indicated by in-torch vaporization inductively-coupled plasma mass spectrometry (ITV-ICP-MS) and electrospray-ionization mass spectrometry (ESI-MS), is consistent with the involvement of a third metal ion in promoting Lewis acid/base type exchange processes.

  4. 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.

  5. Liquid-liquid extraction of metal ions by the 6-membered N-containing macrocycle hexacyclen.

    PubMed

    Arpadjan, S; Mitewa, M; Bontchev, P R

    1987-11-01

    The nitrogen-containing analogue of 18-crown-6, 1,4,7,10,13,16-hexa-azaoctadecane (hexacyclen)] was studied as a reagent for complexation and extraction of some metal ions. It was found that with this reagent and methyl isobutyl ketone, metal ions such as silver(I), mercury(II), copper(II), platinum(II) and palladium(II) can be quantitatively extracted and separated from iron(III) and some other metal ions.

  6. 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

    2016-04-20

    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.

  7. 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

  8. 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

  9. 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.

  10. A novel approach for enhancing metal ion separation using acoustic nebulisation.

    PubMed

    Jimmy, Beenamma; Kolev, Spas D; Kentish, Sandra; Ashokkumar, Muthupandian

    2012-05-01

    A novel technique for anionic surfactant assisted separation and preconcentration of metal cations was developed using ultrasound induced nebulization at MHz frequency. The ions of copper, zinc, cadmium, and calcium were used as model analytes. Analysis of the aerosol using flame atomic absorption spectrometry showed enrichment factors for the metal ions studied between 5 and 8, when dilute solutions containing sodium dodecylsulfate and the metal ions were nebulized. The mechanism of metal ion enrichment was explained based on surfactant adsorption and the droplet model for aerosol droplets. It was demonstrated that further increase in the enrichment factor could be achieved by increasing the ultrasound frequency, thus producing smaller droplets. PMID:22154732

  11. Study of coagulation processes of selected humic acids under copper ions influence*

    NASA Astrophysics Data System (ADS)

    Boguta, Patrycja; Sokolowska, Zofia

    2013-04-01

    Humic acids have limited sorption capacity and big dose of metal or other mineral component which can be sorbed on humic acids, can cause saturation of negative, surface charge of humic acids leading to destabilization of dissolved humic acids compounds. Destabilisation can be observed as coagulation and floculation proces of humic acids. However there are a lot of mechanisms which causing precipitation of humic acids. Thereby, in order to full description of coagulation process, different methods should be applied. Ordinarily, humic acids coagulation is studied by measurement of absorbance, transmittance or carbon loss in solution. Meanwhile, very significant information is also variation of metal content in soil solution and information whether metal goes to precipitate together with humic acids or stays in dissolved form in solution. So, that, from one side, processes of stronger accumulation of metal can lead to soil degradation and micronutrient deficiency for plants. However, there is also possibility to stay metal in solution in toxic and bioavailable form for plants. Main aim of this paper was to study coagulation process of different humic acids extracted from mucking peats under copper ions influence at adjusted pH to 5. In order to this, four peaty-muck soils were taken from selected places in east part of Poland (meadows and river valleys). These soils differed by humification degree, secondary transformation, density and pH. At next step, humic acids were extracted from soils using sodium hydroxide (NaOH) extractant. After exact purification by washing with HF-HCl mixture and water, humic acids were liofilized. Solutions of humic acids were prepared at concentration 40 mg/dm3 with addition of different amount of copper ions to obtain final concentration of Cu(II) ranged from 0-40mg/dm3. After 24 hours solutions were investigated using measurements of absorbance at 470nm (UV-VIS spectrometer Jasco V-530), measurements of organic carbon in solution

  12. 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.

  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.

  14. Inhibitory effect of metal ions on alkaline mesentericopeptidase.

    PubMed

    Raykova, D; Dorovska-Taran, V; Blagoev, B

    1981-01-01

    The effect of AG+, Cu2+, Cd2+, Co2+ and Ni2+ on the activity of alkaline mesentericopeptidase (EC 3.4.21.-) has been studied. Ag+, Cu2+ and Cd2+ were found to be reversible non-competitive inhibitors of the enzyme. The pH-dependence of Ki for Ag+-inhibition is sigmoidal with a pKa near 6. The Kilim values, calculated for the pH-independent region of the metal-enzyme inhibition, are close to the corresponding dissociation constants of metal-imidazole complexes, thus implying that the inhibitory effect of metal ions on enzyme activity is due to complex formation with the imidazole group of the active site histidine. The method of the two-component inhibition showed that Cu2+ and Ag+ bind to the same ligand of the enzyme molecule. The addition of Cu2+ decreases the rate of deacylation of the hydrolysis of p-nitrophenyl valerate, catalyzed by alkaline mesentericopeptidase in contrast to alpha-chymotrypsin where the acylation step is affected.

  15. Preparation, structural characterization and biological evaluation of L-tyrosinate metal ion complexes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Korashy, Sabry A.; Ahmed, Ahmed S.

    2008-06-01

    The complexes formed between different metal ions and biological molecules like amino acids play an important role in human life. Sn(II), Sn(IV), Zn(II), Cd(II), Hg(II), Cr(III), Fe(III), La(III), ZrO(II) and UO 2(II) complexes are synthesized with L-tyrosine (tyr). These complexes are characterized by elemental analysis, molar conductance, magnetic measurements, mass, IR, UV-vis and 1H NMR spectra as well as thermogravimetric analysis (TGA/DTG). It has been found from the elemental analysis and the thermal studies that the ligand behaves as bidentate ligand forming chelates with 1:3 (metal:ligand) stoichiometry for trivalent metals and 1:2 for divalent and tetravalent metals. The molar conductance measurements of the complexes in DMSO indicate that the complexes are non-electrolyte. The activation energies and other kinetic parameters were calculated from the Coats-Redfern and Horowitz-Metzger equations. The biological activities of the metal complexes have also been studied against different bacteria and fungi.

  16. Amide bond cleavage initiated by coordination with transition metal ions and tuned by an auxiliary ligand.

    PubMed

    Yang, Yongpo; Lu, Chunxin; Wang, Hailong; Liu, Xiaoming

    2016-06-21

    The reaction of ligand , N,N-bis(pyridin-2-ylmethyl)acetamide, with five transition metal salts, FeCl3·6H2O, CuCl2·2H2O, Cu(ClO4)2·6H2O, ZnCl2 and K2PtCl4/KI, produced five metal complexes, [(μ-O)(FeClL')(FeCl3)] (), [CuLCl2] (), [CuBPA(ClO4)(CHCN)] ClO4 (), [ZnLCl2] () and [PtLI2] (), where = 1-(2,4,5-tri(pyridin-2-yl)-3-(pyridin-2-ylmethyl)imidazolidin-1-yl)ethanone which formed in situ, and BPA = bis(pyridin-2-ylmethyl)amine. The ligand and complexes were characterized by a variety of spectroscopic techniques including X-ray single crystal diffraction where applicable. Depending on the metal ion and auxiliary ligand of the complex, the acetyl group of the ligand could be either intact or cleaved. When ferric chloride hexahydrate was used, the deacetylation proceeded even further and a novel heterocyclic compound () was formed in situ. A possible mechanism was proposed for the formation of the heterocyclic compound found in complex . Our results indicate that to cleave effectively an amide bond, it is essential for a metal centre to bind to the amide bond and the metal centre is of sufficient Lewis acidity.

  17. Metallic contamination in hydrogen plasma immersion ion implantation of silicon

    NASA Astrophysics Data System (ADS)

    Chu, Paul K.; Fu, Ricky K. Y.; Zeng, Xuchu; Kwok, Dixon T. K.

    2001-10-01

    In plasma immersion ion implantation (PIII), ions bombard all surfaces inside the PIII vacuum chamber, especially the negatively pulsed biased sample stage and to a lesser extent the interior of the vacuum chamber. As a result, contaminants sputtered from these exposed surfaces can be reimplanted into or adsorb on the silicon wafer. Using particle-in-cell theoretical simulation, we determine the relative ion doses incident on the top, side, and bottom surfaces of three typical sample chuck configurations: (i) a bare conducting stage with the entire sample platen and high-voltage feedthrough/supporting rod exposed and under a high voltage, (ii) a stage with only the sample platen exposed to the plasma but the high-voltage feedthrough protected by an insulating quartz shroud, and (iii) a bare stage with a silicon extension or guard ring to reduce the number of ions bombarding the side and bottom of the sample platen. Our simulation results reveal that the ratio of the incident dose impacting the top of the sample platen to that impacting the side and bottom of the sample stage can be improved to 49% using a guard ring. To corroborate our theoretical results, we experimentally determine the amounts of metallic contaminants on 100 mm silicon wafers implanted using a bare chuck and with a 150 mm silicon wafer inserted between the 100 mm wafer and sample stage to imitate the guard ring. We also discuss the effectiveness of a replaceable all-silicon liner inside the vacuum chamber to address the second source of contamination, that from the interior wall of the vacuum chamber. Our results indicate a significant improvement when an all-silicon liner and silicon guard ring are used simultaneously.

  18. 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.

  19. An Experiment on Isomerism in Metal-Amino Acid Complexes.

    ERIC Educational Resources Information Center

    Harrison, R. Graeme; Nolan, Kevin B.

    1982-01-01

    Background information, laboratory procedures, and discussion of results are provided for syntheses of cobalt (III) complexes, I-III, illustrating three possible bonding modes of glycine to a metal ion (the complex cations II and III being linkage/geometric isomers). Includes spectrophotometric and potentiometric methods to distinguish among the…

  20. Adsorption of aqueous metal ions on cattle-manure-compost based activated carbons.

    PubMed

    Zaini, Muhammad Abbas Ahmad; Okayama, Reiko; Machida, Motoi

    2009-10-30

    The objective of this study is to examine the suitability and performance of cattle-manure-compost (CMC) based activated carbons in removing heavy metal ions from aqueous solution. The influence of ZnCl(2) activation ratios and solution pH on the removal of Cu(II) and Pb(II) were studied. Pore texture, available surface functional groups, pH of point zero charge (pH(PZC)), thermogravimetric analysis and elemental compositions were obtained to characterize the activated carbons. Batch adsorption technique was used to determine the metal-binding ability of activated carbons. The equilibrium data were characterized using Langmuir, Freundlich and Redlich-Peterson models. It was found that the uptake of aqueous metal ions by activated carbons could be well described by Langmuir equation. It is suggested that the increase of surface area and mesopore ratio as a result of increasing activation ratios favored the removal of Cu(II), while activated carbon rich in acidic groups showed selective adsorption towards Pb(II). The preferable removal of Cu(II) over Pb(II) could be due to the rich nitrogen content as well as the higher mesoporous surface area in the CMC activated carbons. The impregnated CMC activated carbons also showed a better performance for Cu(II) removal at varying solution pH than Filtrasorb 400 (F400), while a similar performance was observed for Pb(II) removal. PMID:19541418