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Sample records for metal ions including

  1. Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

    Science.gov (United States)

    Cooks, Robert Graham; Li, Anyin; Luo, Qingjie

    2017-08-01

    The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

  2. Multiheteromacrocycles that Complex Metal Ions. Ninth Progress Report (includes results of last three years), 1 May 1980 -- 30 April 1983

    Science.gov (United States)

    Cram, D. J.

    1982-09-15

    The overall objective of this research is to design, synthesize, and evaluate cyclic and polycyclic host organic compounds for the abilities to complex and lipophilize guest metal ions, their complexes, and their clusters. Host organic compounds consist of strategically placed solvating, coordinating, and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions, or by metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; numbers of binding sites; characters of binding sites; and valences. The hope is to synthesize new classes of compounds useful in the separation of metal ions, their complexes, and their clusters.

  3. Native SDS-PAGE: high resolution electrophoretic separation of proteins with retention of native properties including bound metal ions.

    Science.gov (United States)

    Nowakowski, Andrew B; Wobig, William J; Petering, David H

    2014-05-01

    Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is commonly used to obtain high resolution separation of complex mixtures of proteins. The method initially denatures the proteins that will undergo electrophoresis. Although covalent structural features of resolved proteins can be determined with SDS-PAGE, functional properties are destroyed, including the presence of non-covalently bound metal ions. To address this shortcoming, blue-native (BN)-PAGE has been introduced. This method retains functional properties but at the cost of protein resolving power. To address the need for a high resolution PAGE method that results in the separation of native proteins, experiments tested the impact of changing the conditions of SDS-PAGE on the quality of protein separation and retention of functional properties. Removal of SDS and EDTA from the sample buffer together with omission of a heating step had no effect on the results of PAGE. Reduction of SDS in the running buffer from 0.1% to 0.0375% together with deletion of EDTA also made little impact on the quality of the electrophoretograms of fractions of pig kidney (LLC-PK1) cell proteome in comparison with that achieved with the SDS-PAGE method. The modified conditions were called native (N)SDS-PAGE. Retention of Zn(2+) bound in proteomic samples increased from 26 to 98% upon shifting from standard to modified conditions. Moreover, seven of nine model enzymes, including four Zn(2+) proteins that were subjected to NSDS-PAGE retained activity. All nine were active in BN-PAGE, whereas all underwent denaturation during SDS-PAGE. Metal retention after electrophoresis was additionally confirmed using laser ablation-inductively coupled plasma-mass spectrometry and in-gel Zn-protein staining using the fluorophore TSQ.

  4. Ion implantation in metals

    International Nuclear Information System (INIS)

    Vook, F.L.

    1977-02-01

    The application of ion beams to metals is rapidly emerging as a promising area of research and technology. This report briefly describes some of the recent advances in the modification and study of the basic properties of metals by ion implantation techniques. Most of the research discussed illustrates some of the new and exciting applications of ion beams to metals which are under active investigation at Sandia Laboratories, Albuquerque

  5. Selectivity of the highly preorganized tetradentate ligand 2,9-di(pyrid-2-yl)-1,10-phenanthroline for metal ions in aqueous solution, including lanthanide(III) ions and the uranyl(VI) cation.

    Science.gov (United States)

    Carolan, Ashley N; Cockrell, Gregory M; Williams, Neil J; Zhang, Gang; VanDerveer, Donald G; Lee, Hee-Seung; Thummel, Randolph P; Hancock, Robert D

    2013-01-07

    Some metal ion complexing properties of DPP (2,9-Di(pyrid-2-yl)-1,10-phenanthroline) are reported with a variety of Ln(III) (Lanthanide(III)) ions and alkali earth metal ions, as well as the uranyl(VI) cation. The intense π-π* transitions in the absorption spectra of aqueous solutions of 10(-5) M DPP were monitored as a function of pH and metal ion concentration to determine formation constants of the alkali-earth metal ions and Ln(III) (Ln = lanthanide) ions. It was found that log K(1)(DPP) for the Ln(III) ions has a peak at Ln(III) = Sm(III) in a plot of log K(1) versus 1/r(+) (r(+) = ionic radius for 8-coordination). For Ln(III) ions larger than Sm(III), there is a steady rise in log K(1) from La(III) to Sm(III), while for Ln(III) ions smaller than Sm(III), log K(1) decreases slightly to the smallest Ln(III) ion, Lu(III). This pattern of variation of log K(1) with varying size of Ln(III) ion was analyzed using MM (molecular mechanics) and DFT (density functional theory) calculations. Values of strain energy (∑U) were calculated for the [Ln(DPP)(H(2)O)(5)](3+) and [Ln(qpy)(H(2)O)(5)](3+) (qpy = quaterpyrdine) complexes of all the Ln(III) ions. The ideal M-N bond lengths used for the Ln(III) ions were the average of those found in the CSD (Cambridge Structural Database) for the complexes of each of the Ln(III) ions with polypyridyl ligands. Similarly, the ideal M-O bond lengths were those for complexes of the Ln(III) ions with coordinated aqua ligands in the CSD. The MM calculations suggested that in a plot of ∑U versus ideal M-N length, a minimum in ∑U occurred at Pm(III), adjacent in the series to Sm(III). The significance of this result is that (1) MM calculations suggest that a similar metal ion size preference will occur for all polypyridyl-type ligands, including those containing triazine groups, that are being developed as solvent extractants in the separation of Am(III) and Ln(III) ions in the treatment of nuclear waste, and (2) Am(III) is very

  6. Separation of metal ions from aqueous solutions

    Science.gov (United States)

    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 Ions Analysis with Capillary Zone Electrophoresis.

    Science.gov (United States)

    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.

  8. Separators for Li-Ion and Li-Metal Battery Including Ionic Liquid Based Electrolytes Based on the TFSI− and FSI− Anions

    Directory of Open Access Journals (Sweden)

    Marija Kirchhöfer

    2014-08-01

    Full Text Available The characterization of separators for Li-ion or Li-metal batteries incorporating hydrophobic ionic liquid electrolytes is reported herein. Ionic liquids made of N-butyl-N-methylpyrrolidinium (PYR14+ or N-methoxyethyl-N-methylpyrrolidinium (PYR12O1+, paired with bis(trifluoromethanesulfonylimide (TFSI− or bis(fluorosulfonylimide (FSI− anions, were tested in combination with separators having different chemistries and morphologies in terms of wetting behavior, Gurley and McMullin number, as well as Li/(Separator + Electrolyte interfacial properties. It is shown that non-functionalized microporous polyolefin separators are poorly wetted by FSI−-based electrolytes (contrary to TFSI−-based electrolytes, while the ceramic coated separator Separion® allows good wetting with all electrolytes. Furthermore, by comparing the lithium solid electrolyte interphase (SEI resistance evolution at open circuit and during cycling, depending on separator morphologies and chemistries, it is possible to propose a scale for SEI forming properties in the order: PYR12O1FSI > PYR14FSI > PYR14TFSI > PYR12O1TFSI. Finally, the impact the separator morphology is evidenced by the SEI resistance evolution and by comparing Li electrodes cycled using separators with two different morphologies.

  9. Metal vapor vacuum arc ion sources

    International Nuclear Information System (INIS)

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

    1990-06-01

    We have developed a family of metal vapor vacuum are (MEVVA) high current metal ion sources. The sources were initially developed for the production of high current beams of metal ions for heavy ion synchrotron injection for basic nuclear physics research; more recently they have also been used for metal ion implantation. A number of different embodiments of the source have been developed for these specific applications. Presently the sources operate in a pulsed mode, with pulse width of order 1 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, and since the ions produced in the vacuum arc plasma are in general multiply ionized the ion energy is up to several hundred keV. Beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Nearly all of the solid metals of the Periodic Table have been use to produce beam. A number of novel features have been incorporated into the sources, including multiple cathodes and the ability to switch between up to 18 separate cathode materials simply and quickly, and a broad beam source version as well as miniature versions. here we review the source designs and their performance. 45 refs., 7 figs

  10. Metal ions as inflammatory initiators of osteolysis.

    Science.gov (United States)

    Magone, Kevin; Luckenbill, Daniel; Goswami, Tarun

    2015-05-01

    Osteolysis and aseptic loosening currently contribute 75 % of implant failures. Furthermore, with over four million joint replacements projected to be performed in the United States annually, osteolysis and aseptic loosening may continue to pose a significant morbidity. This paper reviews the osteolysis cascade leading to osteoclast activation and bone resorption at the biochemical level. Additionally, the metal ion release mechanism from metallic implants is elucidated. Even though metal ions are not the predominating initiator of osteolysis, they do increase the concentration of key inflammatory cytokines that stimulate osteoclasts and prove to be a contributor to osteolysis and aseptic loosening. Osteolysis is a competitive mechanism among a number of biological reactions, which includes debris release, macrophage and osteoclast activation, an inflammatory response as well as metal ion release. Pharmacological therapy for component loosening has also been reviewed. A non-surgical treatment of osteolysis has not been found in the literature and thus may become an area of future research. Even though this research is warranted, comprehensively understanding the immune response to orthopedic implants and their metallic ions, and thus, creating improved prostheses appears to be the most cost-effective approach to decrease the morbidity related to osteolysis and to design implants with greater longevity. The ionic forms, cytokines, toxicity, gene expression, biological effects, and hypersensitivity responses of metallic elements from metal implants are summarized as well.

  11. Metal ion adsorption characteristics of tea leaves

    OpenAIRE

    Takao, Hiromitsu; Kawahigashi, Tatsuo

    2016-01-01

    [Abstract] For effective use of tea leaves, this study experimentally evaluated metal ion adsorption by tea leaves. The experiment described herein was conducted by measuring the ionic solution at a constant density using a fluorescence X-ray device. The metallic ion concentration in the solution and the fluorescence X-ray output intensity showed good correlation. Tea leaves were put into solution adjusted with density of an already-known metallic ion. Then the decrease of the metal ion was m...

  12. A biosystem for removal of metal ions from water

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Amorphization of metals by ion implantation and ion beam mixing

    International Nuclear Information System (INIS)

    Rauschenbach, B.; Heera, V.

    1988-01-01

    Amorphous metallic systems can be formed either by high-fluence ion implantation of glassforming species or by irradiation of layered metal systems with inert gas ions. Both techniques and experimental examples are presented. Empirical rules are discussed which predict whether a given system can be transformed into an amorphous phase. Influence of temperature, implantation dose and pre-existing crystalline metal composition on amorphization is considered. Examples are given of the implantation induced amorphous structure, recrystallization and formation of quasicrystalline structures. (author)

  14. Metal Ion Controlled Polymorphism of a Peptide

    DEFF Research Database (Denmark)

    Hemmingsen, Lars Bo Stegeager; Jancso, Attila; Szunyogh, Daniel

    2011-01-01

    , …) in the peptide, and the ligand and structural preferences of the metal ion (in our studies Zn2+, Cd2+, Hg2+, Cu+/2+). Simultaneously, new species such as metal ion bridged ternary complexes or even oligomers may be formed. In recent previous studies we have observed similar polymorphism of zinc finger model...

  15. Methods of producing adsorption media including a metal oxide

    Science.gov (United States)

    Mann, Nicholas R; Tranter, Troy J

    2014-03-04

    Methods of producing a metal oxide are disclosed. The method comprises dissolving a metal salt in a reaction solvent to form a metal salt/reaction solvent solution. The metal salt is converted to a metal oxide and a caustic solution is added to the metal oxide/reaction solvent solution to adjust the pH of the metal oxide/reaction solvent solution to less than approximately 7.0. The metal oxide is precipitated and recovered. A method of producing adsorption media including the metal oxide is also disclosed, as is a precursor of an active component including particles of a metal oxide.

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

    Directory of Open Access Journals (Sweden)

    Roxana Ramírez-Sandoval

    2015-01-01

    Full Text Available 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(NO32. 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.

  17. Heavy metal ions are potent inhibitors of protein folding.

    Science.gov (United States)

    Sharma, Sandeep K; Goloubinoff, Pierre; Christen, Philipp

    2008-07-25

    Environmental and occupational exposure to heavy metals such as cadmium, mercury and lead results in severe health hazards including prenatal and developmental defects. The deleterious effects of heavy metal ions have hitherto been attributed to their interactions with specific, particularly susceptible native proteins. Here, we report an as yet undescribed mode of heavy metal toxicity. Cd2+, Hg2+ and Pb2+ proved to inhibit very efficiently the spontaneous refolding of chemically denatured proteins by forming high-affinity multidentate complexes with thiol and other functional groups (IC(50) in the nanomolar range). With similar efficacy, the heavy metal ions inhibited the chaperone-assisted refolding of chemically denatured and heat-denatured proteins. Thus, the toxic effects of heavy metal ions may result as well from their interaction with the more readily accessible functional groups of proteins in nascent and other non-native form. The toxic scope of heavy metals seems to be substantially larger than assumed so far.

  18. Effective charge of energetic ions in metals

    International Nuclear Information System (INIS)

    Kitagawa, M.; Brandt, W.

    1983-01-01

    The effective charge of energetic ion, as derived from stopping power of metals, is calculated by use of a dielectronic-response function method. The electronic distribution in the ion is described through the variational principle in a statistical approximation. The dependences of effective charge on the ion velocity, atomic number and r/sub s/-value of metal are derived at the low-velocity region. The effective charge becomes larger than the real charge of ion due to the close collisions. We obtain the quasi-universal equation of the fractional effective electron number of ion as a function of the ratio between the ionic size and the minimum distance approach. The comparsion between theoretical and experimental results of the effective charge is performed for the cases of N ion into Au, C and Al. We also discuss the equipartition rule of partially ionized ion at the high-velocity region

  19. Biological treatment of inorganic ion contamination including radionuclides

    International Nuclear Information System (INIS)

    Cherry, R.S.

    1997-01-01

    Microorganisms and plants are capable of a broad range of activities useful in treating inorganic contaminants in soil, groundwater, and surface runoff water Among the advantages of biological processes for this purpose are relatively low costs (related to their mild conditions) and the practicality of letting them run unattended. This talk will review both kinds of treatment chemistry that can be done biologically as well as present data from INEEL projects on bioremediation of specific elements. Biological processes can either solubilize or immobilize metals and other ions depending on the need. Uranium ions are solubilized from soil by the local bioproduction of organic acids as chelating agents, allowing removal of this ion as part of an ex-situ treatment process. Further, the microbial production of sulfuric acid can be used to solubilize Cs contamination in concrete surfaces. More usual though is the need to control metal movement in soil or water. Various metals such as Se and Cd are taken up from soil by hyper-accumulating plants, where they can be harvested in concentrated form in the leaves and stems. Excess acidity and a broad variety of toxic metals in acid rock drainage, such as Hg, Cd, Zn and others, can be removed by the production of sulfide ion in an easily fielded biological reactor which may be useful on phosphate processing runoff water contaminated with naturally occuring radioactive materials. Soluble Co, Cu, and Cd can be treated by sorption onto immobilized algae. Inorganic ions can also be directly reduced by bacteria as part of treatment, for example the conversion of soluble selenate ion to insoluble elemental selenium and the conversion of highly toxic CR(VI) to the far less soluble and less toxic Cr(III)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Upgraded vacuum arc ion source for metal ion implantation

    International Nuclear Information System (INIS)

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

    2012-01-01

    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.

  2. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    Science.gov (United States)

    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 ...

  3. [Metal ions: important co-players in aseptic loosening].

    Science.gov (United States)

    Cadosch, D; Schlett, C L; Gautschi, O P; Frei, H C; Filgueira, L

    2010-08-01

    The aims of this review were to discuss the different mechanisms of biocorrosion of orthopaedic metal implants in the human body, as well as the effects of the released metal ions on bone metabolism and the immune system in regard to their involvement in the pathophysiological mechanisms of aseptic loosening and metal hypersensitivity. Implant failure due to aseptic loosening is thought to occur in about 10-15% of cases. A review of the literature (using PubMed with the search terms: biocorrosion, metal ions and bone metabolism) was performed. Additionally, we discuss our research results in the field of aseptic loosening. Despite a great effort in developing new implants, metal devices used in orthopaedic and trauma surgery remain prone to biocorrosion by several mechanisms including the direct corrosion by osteoclasts, leading to the production of significant amounts of wear particles and metal ions. In addition to the well documented increased osteolytic activity caused by large (in the nanometer range) wear particles, increasing evidence strongly suggests that the released metal ions contribute to the pathophysiological mechanism of aseptic loosening. Metal ions stimulate both the immune system and bone metabolism through a series of direct and indirect pathways leading to an increased osteolytic activity at the bone-implant interface. To date, revision surgery remains the only option for the treatment of a failed orthopaedic implant caused by aseptic loosening. A better understanding of the complex pathophysiological mechanisms (including the effects caused by the released metal ions) of aseptic loosening may have a significant potential in developing novel implants and therapies in order to reduce the incidence of this complication. Georg Thieme Verlag KG Stuttgart, New York.

  4. Ion beam analysis of metal ion implanted surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  5. A novel metal ion source for preparing hard coatings

    International Nuclear Information System (INIS)

    Feng, Y.C.; Wong, S.P.

    1999-01-01

    A novel metal ion source, Electron Beam Evaporation Metal Ion Source, has been developed for material modifications. This ion source is based on the electron beam evaporation technology. It can provide gaseous, solid or gaseous and solid mixed intense ion beams for preparing a variety of thin films. In this ion source, a focusing electron beam is used to bombard and vaporize the metal or other solid element within same chamber where the metal or solid atoms are ionized and plasma medium from which ions are extracted is formed by arc discharge. A small aperture diameter extraction system is used for extracting the ion beam from this source. Ion beams of a series of elements, which include C, W, Ta, Mo, Cr, Ti, B, Cu, Ni, Al, Ar, N, C+N, Ti+N, Cr+N, etc., have been extracted. The source has a 3.6 cm extraction diameter. The beam energy ranges from 0.3 to 4 keV for single charge state ions, and the maximum beam current extractable is over 90 mA. The source has been used for preparing hard coatings. The films of carbon nitride and titanium nitride have been synthesized by direct deposition with C+N and Ti+N mixed ion beams. The results have shown to exhibit very high hardness value for carbon nitride films. The microhardness is up to HK 5800 kgf/mm 2 . In comparison with other methods, it is also to exhibit higher hardness value for titanium nitride coating. The highest hardness value obtained for titanium nitride is about 3000 kgf/mm 2 . The AES profile shows that there is a good intermixture between coating and substrate for both films. The principle, structure and performance of this ion source will be described. The preliminary results for forming hard coatings are also presented in this article

  6. Cesium ion bombardment of metal surfaces

    International Nuclear Information System (INIS)

    Tompa, G.S.

    1986-01-01

    The steady state cesium coverage due to cesium ion bombardment of molybdenum and tungsten was studied for the incident energy range below 500 eV. When a sample is exposed to a positive ion beam, the work function decreases until steady state is reached with a total dose of less than ≅10 16 ions/cm 2 , for both tungsten and molybdenum. A steady state minimum work function surface is produced at an incident energy of ≅100 eV for molybdenum and at an incident energy of ≅45 eV for tungsten. Increasing the incident energy results in an increase in the work function corresponding to a decrease in the surface coverage of cesium. At incident energies less than that giving the minimum work function, the work function approaches that of cesium metal. At a given bombarding energy the cesium coverage of tungsten is uniformly less than that of molybdenum. Effects of hydrogen gas coadsorption were also examined. Hydrogen coadsorption does not have a large effect on the steady state work functions. The largest shifts in the work function due to the coadsorption of hydrogen occur on the samples when there is no cesium present. A theory describing the steady-state coverage was developed is used to make predictions for other materials. A simple sticking and sputtering relationship, not including implantation, cannot account for the steady state coverage. At low concentrations, cesium coverage of a target is proportional to the ratio of (1 - β)/γ where β is the reflection coefficient and γ is the sputter yield. High coverages are produced on molybdenum due to implantation and low backscattering, because molybdenum is lighter than cesium. For tungsten the high backscattering and low implantation result in low coverages

  7. Metal ion coupled protein folding and allosteric motions

    Science.gov (United States)

    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.

  8. Fluorescence signalling of the transition metal ions: Design strategy ...

    Indian Academy of Sciences (India)

    on fluorescence signalling systems for the transition metal ions. It is shown that even simple fluorophore-spacer-receptor systems can display excellent off-on fluorescence signalling towards the quenching metal ions when the fluorophore ...

  9. Metallic ion release after knee prosthesis implantation: a prospective study.

    Science.gov (United States)

    Lons, Adrien; Putman, Sophie; Pasquier, Gilles; Migaud, Henri; Drumez, Elodie; Girard, Julien

    2017-12-01

    Metal-on-metal (MoM) hip replacement bearings produce metallic ions that can cause health complications. Metallic release also occurs with other materials, but data on metallic ion levels after knee arthroplasty are sparse. We postulate that knee replacement generates elevating metallic ions (chromium (Cr), cobalt (Co) and titanium (Ti)) during the first year after implantation. This ongoing prospective study included all patients who underwent the same type of knee arthroplasty between May and December 2013. Cr, Co and Ti levels were measured in whole blood at pre-operation and one-year follow-up (6 and 12 months). Clinical and radiographic data (range of motion, Oxford, International Knee Society (IKS) and satisfaction scores) were recorded. In 90 patients, preoperative Cr, Co and Ti metallic ion levels were respectively 0.45 μg/l, 0.22 μg/l, 2.94 μg/l and increased to 1.27 μg/l, 1.41 μg/l, 4.08 μg/l (p < 0.0001) at last one-year follow-up. Mean Oxford and IKS scores rose, respectively, from 45.9 (30-58) and 24.9 (12-52) to 88.3 (0-168) and 160.8 (93-200) (p < 0.001). After the implantation of knee arthroplasty, we found significant blood elevation of Cr, Co and Ti levels one year after implantation exceeding the normal values. This metallic ion release could lead to numerous effects: allergy, hypersensitivity, etc.

  10. Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

    Science.gov (United States)

    Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.

    2017-12-01

    High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

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

    Science.gov (United States)

    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. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  12. Dimeric Complexes of Tryptophan with M2+ Metal Ions

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

    2009-01-01

    IRMPD spectroscopy using the FELIX free electron laser and a Fourier transform ICR mass spectrometer was used to characterize the structures of electrosprayed dimer complexes M(2+)Trp(2) of tryptophan with a series of eight doubly charged metal ions, including alkaline earths Ca, Sr, and Ba, and

  13. Heavy metal ion uptake properties of polystyrene-supported ...

    Indian Academy of Sciences (India)

    Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration on the uptake of metal ions have been studied. The uptake of metal ion ...

  14. Engineering of microorganisms towards recovery of rare metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, Kouichi; Ueda, Mitsuyoshi [Kyoto Univ. (Japan). Div. of Applied Life Sciences

    2010-06-15

    The bioadsorption of metal ions using microorganisms is an attractive technology for the recovery of rare metal ions as well as removal of toxic heavy metal ions from aqueous solution. In initial attempts, microorganisms with the ability to accumulate metal ions were isolated from nature and intracellular accumulation was enhanced by the overproduction of metal-binding proteins in the cytoplasm. As an alternative, the cell surface design of microorganisms by cell surface engineering is an emerging strategy for bioadsorption and recovery of metal ions. Cell surface engineering was firstly applied to the construction of a bioadsorbent to adsorb heavy metal ions for bioremediation. Cell surface adsorption of metal ions is rapid and reversible. Therefore, adsorbed metal ions can be easily recovered without cell breakage, and the bioadsorbent can be reused or regenerated. These advantages are suitable for the recovery of rare metal ions. Actually, the cell surface display of a molybdate-binding protein on yeast led to the enhanced adsorption of molybdate, one of the rare metal ions. An additional advantage is that the cell surface display system allows high-throughput screening of protein/peptide libraries owing to the direct evaluation of the displayed protein/peptide without purification and concentration. Therefore, the creation of novel metal-binding protein/ peptide and engineering of microorganisms towards the recovery of rare metal ions could be simultaneously achieved. (orig.)

  15. Development of a four-zone carousel process packed with metal ion-imprinted polymer for continuous separation of copper ions from manganese ions, cobalt ions, and the constituent metal ions of the buffer solution used as eluent.

    Science.gov (United States)

    Jo, Se-Hee; Park, Chanhun; Yi, Sung Chul; Kim, Dukjoon; Mun, Sungyong

    2011-08-19

    A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Activation of Methane by Gaseous Metal Ions

    Czech Academy of Sciences Publication Activity Database

    Schröder, Detlef

    2010-01-01

    Roč. 49, č. 5 (2010), s. 850-851 ISSN 1433-7851 Grant - others:European Research Council(XE) AdG HORIZOMS Institutional research plan: CEZ:AV0Z40550506 Keywords : C-C coupling * C-H bond activation * gas-phase reactions * metal ions * methane Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 12.730, year: 2010

  17. IDENTIFICATION OF CATALYTIC METAL ION LIGANDS IN RIBOZYMES

    Science.gov (United States)

    Frederiksen, John K.; Piccirilli, Joseph A.

    2012-01-01

    Site-bound metal ions participate in the catalytic mechanisms of many ribozymes. Understanding these mechanisms therefore requires knowledge of the specific ligands on both substrate and ribozyme that coordinate these catalytic metal ions. A number of different structural and biochemical strategies have been developed and refined for identifying metal ion binding sites within ribozymes, and for assessing the catalytic contributions of the metal ions bound at those sites. We review these approaches and provide examples of their application, focusing in particular on metal ion rescue experiments and their roles in the construction of the transition state models for the Tetrahymena group I and RNase P ribozymes. PMID:19651216

  18. Ion-induced effects on metallic nanoparticles

    International Nuclear Information System (INIS)

    Klimmer, Andreas

    2010-01-01

    This work deals with the ion-irradiation of metallic nanoparticles in combination with various substrates. Particle diameters were systematically varied within the range of 2.5-14 nm, inter-particle distances range from 30-120 nm. Irradiations were performed with various inert gas ions with energies of 200 keV, resulting in an average ion range larger than the particle dimensions and therefore the effects of irradiation are mainly due to creation of structural defects within the particles and the underlying substrate as well. The main part of this work deals with ion-induced burrowing of metallic nanoparticles into the underlying substrate. The use of micellar nanoparticles with sharp size distribution combined with AFM and TEM analysis allows a much more detailed look at this effect than other works on that topic so far. With respect to the particle properties also a detailed look on the effect of irradiation on the particle structure would be interesting, which might lead to a deliberate influence on magnetic properties, for example. Within the context of this work, first successful experiments were performed on FePt particles, showing a significant reduction of the ordering temperature leading to the magnetically interesting, ordered L1 0 phase. (orig.)

  19. Immobilization of Metal Hexacyanoferrate Ion-Exchangers for the Synthesis of Metal Ion Sorbents—A Mini-Review

    Directory of Open Access Journals (Sweden)

    Thierry Vincent

    2015-11-01

    Full Text Available Metal hexacyanoferrates are very efficient sorbents for the recovery of alkali and base metal ions (including radionuclides such as Cs. Generally produced by the direct reaction of metal salts with potassium hexacyanoferrate (the precursors, they are characterized by ion-exchange and structural properties that make then particularly selective for Cs(I, Rb(I and Tl(I recovery (based on their hydrated ionic radius consistent with the size of the ion-exchanger cage, though they can bind also base metals. The major drawback of these materials is associated to their nanometer or micrometer size that makes them difficult to recover in large-size continuous systems. For this reason many techniques have been designed for immobilizing these ion-exchangers in suitable matrices that can be organic (mainly polymers and biopolymers or inorganic (mineral supports, carbon-based matrices. This immobilization may proceed by in situ synthesis or by entrapment/encapsulation. This mini-review reports some examples of hybrid materials synthesized for the immobilization of metal hexacyanoferrate, the different conditionings of these composite materials and, briefly, the parameters to take into account for their optimal design and facilitated use.

  20. Evaluation of complexing agents and column temperature in ion chromatographic separation of alkali metals, alkaline earth metals and transition metals ion

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Pandey, Ashish; Name, Anil B.; Das, D.K.; Behere, P.G.; Mohd Afzal

    2015-01-01

    The aim of ion chromatography method development is the resolution of all metal ions of interests. Resolution can be improved by changing the selectivity. Selectivity in chromatography can be altered by changes in mobile phase (eg eluent type, eluent strength) or through changes in stationary phase. Temperature has been used in altering the selectivity of particularly in reversed phase liquid chromatography and ion exchange chromatography. Present paper describe the retention behaviour of alkali metals, alkaline earth metals and transition metal ions on a silica based carboxylate function group containing analyte column. Alkali metals, alkaline earth metals and transition metal ions were detected by ion conductivity and UV-VIS detectors respectively

  1. Transparent monolithic metal ion containing nanophase aerogels

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Alkali metal ion templated transition metal formate framework materials: synthesis, crystal structures, ion migration, and magnetism.

    Science.gov (United States)

    Eikeland, Espen; Lock, Nina; Filsø, Mette; Stingaciu, Marian; Shen, Yanbin; Overgaard, Jacob; Iversen, Bo Brummerstedt

    2014-10-06

    Four transition metal formate coordination polymers with anionic frameworks, namely, Na[Mn(HCOO)3], K[Mn(HCOO)3], Na2[Cu3(HCOO)8], and K2[Cu5(HCOO)12], were synthesized using a mild solution chemistry approach. Multitemperature single-crystal (100-300 K) and powder X-ray diffraction studies of the compounds reveal structures of large diversity ranging from cubic chiral Na-Mn formate to triclinic Na-Cu formate. The structural variety is caused by the nature of the transition metals, the alkali metal ion templation, and the versatility of the formate group, which offers metal-metal coordination through three different O-C-O bridging modes (syn-syn, syn-anti, anti-anti) in addition to metal-metal bridging via a single oxygen atom. The two manganese(II) compounds contain mononuclear, octahedrally coordinated moieties, but the three-dimensional connectivity between the manganese octahedra is very different in the two structures. The two copper frameworks, in contrast, consist of binuclear and mononuclear moieties (Na-Cu formate) and trinuclear and mononuclear moieties (K-Cu formate), respectively. Procrystal electron density analysis of the compounds indicates one-dimensional K(+)-ion conductivity in K-Mn and K-Cu, and the nature of the proposed potassium ion migration is compared with results from similar analysis on known Na(+) and K(+) ion conductors. K-Mn and Na-Mn were tested as cathode materials, but this resulted in poor reversibility due to low conductivity or structural collapse. The magnetic properties of the compounds were studied by vibrating sample magnetometric measurements, and their thermal stabilities were determined by thermogravimetric analysis and differential thermal analysis. Despite structural differences, the metal formates that contain the same transition metal have similar magnetic properties and thermal decomposition pathways, that is, the nature of the transition metal controls the compound properties.

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

    Science.gov (United States)

    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.

  4. THE ROLES OF METAL IONS IN REGULATION BY RIBOSWITCHES

    OpenAIRE

    Ferré-D'Amaré, Adrian; Winkler, Wade C.

    2011-01-01

    Metal ions are required by all organisms in order to execute an array of essential molecular functions. They play a critical role in many catalytic mechanisms and structural properties. Proper homeostasis of ions is critical; levels that are aberrantly low or high are deleterious to cellular physiology. To maintain stable intracellular pools, metal ion-sensing regulatory (metalloregulatory) proteins couple metal ion concentration fluctuations with expression of genes encoding for cation trans...

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

    International Nuclear Information System (INIS)

    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

  6. Nonlinear waves in electron–positron–ion plasmas including charge ...

    Indian Academy of Sciences (India)

    The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are ...

  7. Nonlinear waves in electron–positron–ion plasmas including charge ...

    Indian Academy of Sciences (India)

    This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and ...

  8. Modification of medical metals by ion implantation of copper

    Science.gov (United States)

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

    2007-10-01

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

  9. Metal ion separations using reactive membranes

    International Nuclear Information System (INIS)

    Way, J.D.

    1993-01-01

    A membrane is a barrier between two phases. If one component of a mixture moves through the membrane faster than another mixture component, a separation can be accomplished. Membranes are used commercially for many applications including gas separations, water purification, particle filtration, and macromolecule separations (Abelson). There are two points to note concerning this definition. First, a membrane is defined based on its function, not the material used to make the membrane. Secondly, a membrane separation is a rate process. The separation is accomplished by a driving force, not by equilibrium between phases. Liquids that are immiscible with the feed and product streams can also be used as membrane materials. Different solutes will have different solubilities and diffusion coefficients in a liquid. The product of the diffusivity and the solubility is known as the permeability coefficient, which is proportional to the solute flux. Differences in permeability coefficient will produce a separation between solutes at constant driving force. Because the diffusion coefficients in liquids are typically orders of magnitude higher than in polymers, a larger flux can be obtained. Further enhancements can be accomplished by adding a nonvolatile complexation agent to the liquid membrane. One can then have either coupled or facilitated transport of metal ions through a liquid membrane. The author describes two implementations of this concept, one involving a liquid membrane supported on a microporous membrane, and the other an emulsion liquid membrane, where separation occurs to internal receiving phases. Applications and costing studies for this technology are reviewed, and a brief summary of some of the problems with liquid membranes is presented

  10. Heavy metal ion uptake properties of polystyrene-supported ...

    Indian Academy of Sciences (India)

    Unknown

    at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of resins follow Freundlich's equation. The resins are recyclable and are therefore employed for the removal of heavy metal pollutants from industrial waste water. Keywords. Uptake properties; heavy metal ion; selectivity; recyclability. 1.

  11. [Metal ion concentrations in patients with metal-metal bearings in prostheses].

    Science.gov (United States)

    Kretzer, J P; Van Der Straeten, C; Sonntag, R; Müller, U; Streit, M; Moradi, B; Jäger, S; Reinders, J

    2013-08-01

    Increased wear leads to elevated systemic and local metal ion concentrations for patients treated with metal-on-metal bearings. The local metal ion content in the close environment of the joint replacement (e.g. joint aspirate or tissue) is several times higher compared to the systemic metal content (e.g. in blood or serum). As a result of increased metal ion levels, local and systemic effects, such as osteolysis, pseudotumors, sensitization or in rare cases toxicity may occur. Although the definition of a specific threshold to define clinical problems is difficult due to a lack of sensitivity, the systemic metal concentration is frequently measured clinically. Currently a threshold for cobalt and chromium between 4 µg/l and 7 µg/l is under debate. Very high levels (≥ 20 µg/l) or a steady increase over time should be a warning sign; however, metal ion levels should not be interpreted as a single diagnostic tool but rather in the entire context of the clinical, radiological and cross-sectional imaging, metal artefact reduction sequence (MARS) magnetic resonance imaging (MRI), ultrasound and computed tomography (CT) findings.

  12. The roles of metal ions in regulation by riboswitches.

    Science.gov (United States)

    Ferré-D'Amaré, Adrian R; Winkler, Wade C

    2011-01-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Heavy metal ion uptake properties of polystyrene-supported ...

    Indian Academy of Sciences (India)

    Unknown

    concentration on the uptake of metal ions have been studied. The uptake of metal ion depends on pH. The resins are more selective at pH 10 for Pb(II) and Hg(II), whereas at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of resins follow Freundlich's equation. The resins are recyclable and ...

  17. Blood metal ion concentrations in metal-on-metal total hip arthroplasty.

    Science.gov (United States)

    Ohtsuru, Tadahiko; Morita, Yuji; Murata, Yasuaki; Shimamoto, Shuji; Munakata, Yutaro; Kato, Yoshiharu

    2017-05-01

    The hip placement with a metal-on-metal (MOM) bearing has been used for both surface replacement and total hip arthroplasty (THA). Use of MOM bearing for hip replacement reduces the wear compared to conventional bearings. We prospectively assessed 30 patients who underwent unilateral MOM THA. A control group of 30 patients who underwent metal-on-polyethylene THA using the implants as the other group, except for bearing, were accessed. Blood samples were collected preoperatively and at 3- , 6- , 9- , 12- , 15- , 18- , and 24-month intervals. Changes in mean blood metal ion concentration were compared between the MOM and metal-on-polyethylene groups. A statistically significant positive correlation was observed between blood cobalt and chromium concentrations in all of the patients. The mean blood ion concentrations of the MOM were significantly higher than those of the metal-on-polyethylene. A statistically significant negative correlation was found between maximum blood cobalt concentration and cup version angle. The maximum blood chromium concentrations in the patients who had larger cup version angles were more likely to decrease. We considered that cup version angle is one of the factors that have the greatest effect on blood metal ion concentration, and the target cup version angle that did not induce an increase in blood metal ion concentrations was approximately 20°.

  18. Sorption of metal ions on synthetic organo-inorganic ion exchanger polyacrylonitrile-Ti(IV) tungstophosphate

    International Nuclear Information System (INIS)

    Haidary, A.; Ahmadi, S. J.; Asadi, M. R.; Asgharizadeh, F.; Ashtari, P.

    2010-01-01

    In this study two Polyacrylonitrile-Ti(IV) tungstophosphate organo-inorganic ion exchangers with different molar ratios have been synthesized. These ion exchangers have been characterized by fourier transform-IR, X- ray diffraction, thermal gravimetric, scanning electron microscopy and CHNSO techniques and their cation exchange capacity bas been measured by continuous method. Distribution coefficients (K d ) for metal ions and radionuclides were determined by batch method and with these ion exchangers, separation of metal ions was achieved on a glass column.

  19. Plasma immersion ion implantation for reducing metal ion release

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J. [Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain); Leibniz-Institut fuer Oberflaechenmodifizierung, 04318 Leipzig (Germany); Universidad de Oviedo, Departamento Quimica Fisica y Analitica (Spain); Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain)

    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.

  20. Metal ions potentiate microglia responsiveness to endotoxin.

    Science.gov (United States)

    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. Copyright © 2015. Published by Elsevier B.V.

  1. Backscattering of light ions from metal surfaces

    International Nuclear Information System (INIS)

    Verbeek, H.

    1975-07-01

    When a metal target is bombarded with light ions some are implanted and some are reflected from the surface or backscattered from deeper layers. This results in an energy distribution of the backscattered particles which reaches from zero to almost the primary energy. The number of the backscattered particles and their energy, angular, and charge distributions depends largely on the energy and the ion target combination. For high energies (i.e., greater than50 keV for protons) particles are backscattered in a single collision governed by the Rutherford cross section. Protons and He-ions with energies of 100 keV to several MeV are widely used for thin film analysis. For lower energies multiple collisions and the screening of the Coulomb potential have to be taken into account, which makes the theoretical treatment more difficult. This energy region is, however, of special interest in the field of nuclear fusion research. Some recent results for energies below 20 keV are discussed in some detail. (auth)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Chromatography of metal ions with a triazine chelating resin

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.N.

    1979-05-01

    The synthesis, characterization, and some analytical applications of a new triazine resin are described. Separation of group IB, IIB, VIB, and VIIB metal ions from group VIII metal ions is achieved by this PDT-4 resin. Calcium(II) and magnesium(II) are taken up at pH = 6, 0.1 M acetate and are eluted at pH = 6, 0.1 M sodium nitrate. Copper(II) is retained at pH = 6, 0.1 M acetate and pH = 1 hydrochloric acid and is eluted subsequently by 5 M perchloric acid. Molybdenum(VI) is sorbed selectively from 0.1 N sulfuric acid or hydrochloric acid and is eluted in a tight band by 0.1 N sodium hydroxide. Numerous rapid column chromatographic separations are reported using this new resin, including analysis of NBS standard samples.

  4. Chromatography of metal ions with a triazine chelating resin

    International Nuclear Information System (INIS)

    Wang, W.N.

    1979-05-01

    The synthesis, characterization, and some analytical applications of a new triazine resin are described. Separation of group IB, IIB, VIB, and VIIB metal ions from group VIII metal ions is achieved by this PDT-4 resin. Calcium(II) and magnesium(II) are taken up at pH = 6, 0.1 M acetate and are eluted at pH = 6, 0.1 M sodium nitrate. Copper(II) is retained at pH = 6, 0.1 M acetate and pH = 1 hydrochloric acid and is eluted subsequently by 5 M perchloric acid. Molybdenum(VI) is sorbed selectively from 0.1 N sulfuric acid or hydrochloric acid and is eluted in a tight band by 0.1 N sodium hydroxide. Numerous rapid column chromatographic separations are reported using this new resin, including analysis of NBS standard samples

  5. Metal ion binding to iron oxides

    NARCIS (Netherlands)

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

    2006-01-01

    The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to

  6. Rod-shaped ion exchanger useful for purifying liquids or recovering components from liquids comprises a metal wire core surrounded by an ion-exchange resin

    NARCIS (Netherlands)

    Koopman, C.; Witkamp, G.J.

    2002-01-01

    Rod-shaped ion exchanger comprises a metal wire core surrounded by an ion-exchange resin. Independent claims are also included for: (1) a module comprising a housing with an inlet and outlet and one or more ion exchangers as above; (2) a process for producing an ion exchanger as above, comprising

  7. Role of metal ions in the destruction of TATP: theoretical considerations.

    Science.gov (United States)

    Dubnikova, Faina; Kosloff, Ronnie; Oxley, Jimmie C; Smith, James L; Zeiri, Yehuda

    2011-09-29

    The safe decomposition of solid TATP (triacetone triperoxide) explosive is examined theoretically. The route to destruction starts with formation of metal complexes between a metal ion and the TATP molecule. The second step is decomposition of the molecules into stable final products. We examined the structure and stability of both metal ion (including Na(+), Cu(+), Cu(2+), Co(2+), and Zn(2+)) and proton complexes with TATP using quantum chemical calculations at the DFT-PBE0 level of theory. In addition, for each ion complex, we determined the initial steps in the pathway to decomposition together with the associated transition states. We find that the products of decomposition, in particular, acetone, are also stabilized by ion metal complexes. In agreement with experiment, we find the best candidates for metal ion induced decomposition are Cu(2+) and Zn(2+).

  8. Functional nucleic acid-based sensors for heavy metal ion assays.

    Science.gov (United States)

    Zhu, Guichi; Zhang, Chun-yang

    2014-12-21

    Heavy metal contaminants such as lead ions (Pb(2+)), mercury ions (Hg(2+)) and silver ions (Ag(+)) can cause significant harm to humans and generate enduring bioaccumulation in ecological systems. Even though a variety of methods have been developed for Pb(2+), Hg(2+) and Ag(+) assays, most of them are usually laborious and time-consuming with poor sensitivity. Due to their unique advantages of excellent catalytic properties and high affinity for heavy metal ions, functional nucleic acids such as DNAzymes and aptamers show great promise in the development of novel sensors for heavy metal ion assays. In this review, we summarize the development of functional nucleic acid-based sensors for the detection of Pb(2+), Hg(2+) and Ag(+), and especially focus on two categories including the direct assay and the amplification-based assay. We highlight the emerging trends in the development of sensitive and selective sensors for heavy metal ion assays as well.

  9. Recent Advances in Antimicrobial Hydrogels Containing Metal Ions and Metals/Metal Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Fazli Wahid

    2017-11-01

    Full Text Available Recently, the rapid emergence of antibiotic-resistant pathogens has caused a serious health problem. Scientists respond to the threat by developing new antimicrobial materials to prevent or control infections caused by these pathogens. Polymer-based nanocomposite hydrogels are versatile materials as an alternative to conventional antimicrobial agents. Cross-linking of polymeric materials by metal ions or the combination of polymeric hydrogels with nanoparticles (metals and metal oxide is a simple and effective approach for obtaining a multicomponent system with diverse functionalities. Several metals and metal oxides such as silver (Ag, gold (Au, zinc oxide (ZnO, copper oxide (CuO, titanium dioxide (TiO2 and magnesium oxide (MgO have been loaded into hydrogels for antimicrobial applications. The incorporation of metals and metal oxide nanoparticles into hydrogels not only enhances the antimicrobial activity of hydrogels, but also improve their mechanical characteristics. Herein, we summarize recent advances in hydrogels containing metal ions, metals and metal oxide nanoparticles with potential antimicrobial properties.

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

    Science.gov (United States)

    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. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Cleavage reactions of the complex ions derived from self-complementary deoxydinucleotides and alkali-metal ions using positive ion electrospray ionization with tandem mass spectrometry.

    Science.gov (United States)

    Xiang, Yun; Abliz, Zeper; Takayama, Mitsuo

    2004-05-01

    The dissociation reactions of the adduct ions derived from the four self-complementary deoxydinucleotides, d(ApT), d(TpA), d(CpG), d(GpC), and alkali-metal ions were studied in detail by positive ion electrospray ionization multiple-stage mass spectrometry (ESI-MS(n)). For the [M + H](+) ions of the four deoxydinucleotides, elimination of 5'-terminus base or loss of both of 5'-terminus base and a deoxyribose were the major dissociation pathway. The ESI-MS(n) spectra showed that Li(+), Na(+), and Cs(+) bind to deoxydinucleotides mainly by substituting the H(+) of phosphate group, and these alkali-metal ions preferred to bind to pyrimidine bases rather than purine bases. For a given deoxydinucleotide, the dissociation pathway of [M + K](+) ions differed clearly from that of [M + Li](+), [M + Na](+), and [M + Cs](+) ions. Some interesting and characteristic cleavage reactions were observed in the product-ion spectra of [M + K](+) ions, including direct elimination of deoxyribose and HPO(3) from molecular ions. The fragmentation behavior of the [M + K](+) and [M + W](+) (W = Li, Na, Cs) adduct ions depend upon the sequence of bases, the interaction between alkali-metal ions and nucleobases, and the steric hindrance caused by bases.

  12. Coordination of cassava starch to metal ions and thermolysis of ...

    African Journals Online (AJOL)

    Cassava starch formed Werner-type complexes with ions of metals from the transition groups. This was proven by conductivity and electron paramagnetic resonance measurements. The coordination of starch to central metal ions influenced the thermal decomposition of starch. As a rule complexes started to decompose at ...

  13. COORDINATION OF CASSAVA STARCH TO METAL IONS AND ...

    African Journals Online (AJOL)

    a

    ABSTRACT. Cassava starch formed Werner-type complexes with ions of metals from the transition groups. This was proven by conductivity and electron paramagnetic resonance measurements. The coordination of starch to central metal ions influenced the thermal decomposition of starch. As a rule complexes started to ...

  14. Metal ion binding with dehydroannulenes – Plausible two ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. Theoretical investigations have been carried out at B3LYP/6-311++G** level of theory to study the binding interaction of various metal ions, Li+, Na+ and K+ with dehydroannulene systems. The present study reveals that alkali metal ions bind strongly to dehydroannulenes and the passage through the central.

  15. Metal ion sequestration: An exciting dimension for molecularly ...

    African Journals Online (AJOL)

    Metal ion sequestration: An exciting dimension for molecularly imprinted polymer technology. DMS Mosha, LL Mkayula. Abstract. The use of a tight binding macrocyclic ligand to complex a metal ion so that this serves as receptee on the Molecularly Imprinted Polymer (MIP) receptor as described here affords a sequestration ...

  16. Interaction of Hydroxyproline with Bivalent Metal Ions in Chemical ...

    African Journals Online (AJOL)

    NICO

    The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were ... metal ions have several significant applications in biological systems.3–20 Beryllium is one ... 1 filter paper for chromatography was used for the purpose of electrophoresis. An Elico ...

  17. Chromatography Of Metal Ions On Wood Cellulose Impregnated ...

    African Journals Online (AJOL)

    Adsorption chromatography of some heavy metal ions on wood cellulose of saw dust (wood waste dust) modified with hydrochloric acid, urea and thiourea was studied. Atomic absorption spectrophotometry (AAS) was used to determine the initial concentration of solutions of Zn2+, Cu2+, Ni2+, Pb2+, and Fe3+ metal ions.

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

    NARCIS (Netherlands)

    Milheiro, A.; Nozaki, K.; Kleverlaan, C.J.; Muris, J.; Miura, H.; Feilzer, A.J.

    2016-01-01

    The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in

  19. Fluorescence signalling of the transition metal ions: Design strategy ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Transition metal ions are notorious for their fluorescence quenching abilities. In this paper, we discuss the design strategies for the development of efficient off-on fluorescence signalling systems for the transition metal ions. It is shown that even simple fluorophore-spacer-receptor systems can display excellent.

  20. Coprecipitation of alkali metal ions with calcium carbonate

    International Nuclear Information System (INIS)

    Okumura, Minoru; Kitano, Yasushi

    1986-01-01

    The coprecipitation of alkali metal ions Li + , Na + , K + and Rb + with calcium carbonate has been studied experimentally and the following results have been obtained: (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite and their ionic radii shows a parabolic curve with a peak located at Na + which has approximately the same ionic radius as Ca 2+ . (3) However, the amounts of alkali metal ions coprecipitated with calcite decrease with increasing ionic radius of alkali metals. (4) Our results support the hypothesis that (a) alkali metals are in interstitial positions in the crystal structure of calcite and do not substitute for Ca 2+ in the lattice, but (b) in aragonite, alkali metals substitute for Ca 2+ in the crystal structure. (5) Magnesium ions in the parent solution increase the amounts of alkali metal ions (Li + , Na + , K + and Rb + ) coprecipitated with calcite but decrease those with aragonite. (6) Sodium-bearing aragonite decreases the incorporation of other alkali metal ions (Li + , K + and Rb + ) into the aragonite. (author)

  1. Which metal or ion? Identification of metals and ions in protein structures

    Czech Academy of Sciences Publication Activity Database

    Dohnálek, Jan

    2014-01-01

    Roč. 70, Supplement /August/ (2014), C1484 ISSN 0108-7673. [Congress and General Assembly of the International Union of Crystallography /23./ - IUCr 2014. 05.08.2014-12.08.2014, Montreal] R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : metal s * ions * structure validation Subject RIV: CE - Biochemistry

  2. Metal ion transport in eukaryotic microorganisms: insights from Saccharomyces cerevisiae.

    Science.gov (United States)

    Eide, D J

    2000-01-01

    Metal ions such as iron, copper, manganese, and zinc are essential nutrients for all eukaryotic microorganisms. Therefore, these organisms possess efficient uptake mechanisms to obtain these nutrients from their extracellular environment. Metal ions must also be transported into intracellular organelles where they function as catalytic and structural cofactors for compartmentalized enzymes. Thus, intracellular transport mechanisms are also present. When present in high levels, metal ions can also be toxic, so their uptake and intracellular transport is tightly regulated at both transcriptional and post-transcriptional levels to limit metal ion overaccumulation and facilitate storage and sequestration. Remarkable molecular insight into these processes has come from recent studies of the yeast Saccharomyces cerevisiae. This organism, which is the primary subject of this chapter, serves as a useful paradigm to understand metal ion metabolism in other eukaryotic microbes.

  3. High energy metal ion implantation using 'Magis', a novel, broad-beam, Marx-generator-based ion source

    International Nuclear Information System (INIS)

    Anders, A.; Brown, I.G.; Dickinson, M.R.; MacGill, R.A.

    1996-08-01

    Ion energy of the beam formed by an ion source is proportional to extractor voltage and ion charge state. Increasing the voltage is difficult and costly for extraction voltage over 100 kV. Here we explore the possibility of increasing the charge states of metal ions to facilitate high-energy, broad beam ion implantation at a moderate voltage level. Strategies to enhance the ion charge state include operating in the regimes of high-current vacuum sparks and short pulses. Using a time-of-flight technique we have measured charge states as high as 7+ (73 kA vacuum spark discharge) and 4+ (14 kA short pulse arc discharge), both for copper, with the mean ion charge states about 6.0 and 2.5, respectively. Pulsed discharges can conveniently be driven by a modified Marx generator, allowing operation of ''Magis'' with a single power supply (at ground potential) for both plasma production and ion extraction

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

    Science.gov (United States)

    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.

  5. removal of heavy metal ions from aqueous solution using rice husks ...

    African Journals Online (AJOL)

    User

    chemical methods have been deployed to remove toxic heavy metals from waste water. Such methods include ion exchange, reverse osmosis, electrochemical precipitation, electro-dialysis, evaporation and solvent extraction (Rohaizer et al. 2013).

  6. Metal ion binding with dehydroannulenes – Plausible two ...

    Indian Academy of Sciences (India)

    WINTEC

    has highest interaction energy of –50∙6 kcal/mol at. B3LYP/6-311++G** level and is 128∙0 kcal/mol more than 1′-K+ complex. Understandably, the binding energy of metal complexes decreases with increase in the size of the metal ion, in accordance with ear- lier results.16,21. Placement of the metal ions at the centroid of ...

  7. Track structure for low energy ions including charge exchange processes

    International Nuclear Information System (INIS)

    Uehara, S.; Nikjoo, H.

    2002-01-01

    The model and development is described of a new generation of Monte Carlo track structure codes. The code LEAHIST simulates full slowing down of low-energy proton history tracks in the range 1 keV-1 MeV and the code LEAHIST simulates low-energy alpha particle history tracks in the range 1 keV-8 MeV in water. All primary ion interactions are followed down to 1 keV and all electrons to 1 eV. Tracks of secondary electrons ejected by ions were traced using the electron code KURBUC. Microdosimetric parameters derived by analysis of generated tracks are presented. (author)

  8. A new design of the sputter type metal ion source and its characteristics of ion beam extraction

    International Nuclear Information System (INIS)

    Kim, W.; Choi, B.H.; Jin, J.T.; Jung, K.S.; Do, S.H.; Chung, K.H.

    1993-01-01

    In an attempt to get a high current metal ion beam of various solid elements including refractory metals, a gaseous duoPIGatron ion source was modified by placing a grid type cathode and a sputter target in the PIG chamber. Tungsten mesh was adopted as the cathode grid, and Ar gas was used for a support gas for sputter induction. For Cu, Fe, and Al, ion current and ratio of the metal ion were obtained at various conditions of sputtering voltage, support gas pressure, arc current, magnet current, and beam extraction voltage. Results showed that the metal current density is linearly changed with the sputtering voltage and magnet current. Ratio of the metal ion in the total current is larger at lower support gas pressure. Current densities for Al, Cu, and Fe were 4 mA/cm 2 , 5.5 mA/cm 2 , and 2 mA/cm 2 , respectively, at an arc current of 3 A, extraction voltage of 20 kV, and a sputtering voltage of 1 kV. Ratios of the metals in the extracted ion currents were 9%, 8%, and 5% for Al, Cu, and Fe, respectively

  9. Alkali metal ion battery with bimetallic electrode

    Science.gov (United States)

    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.

  10. A review on various electrochemical techniques for heavy metal ions detection with different sensing platforms.

    Science.gov (United States)

    Bansod, BabanKumar; Kumar, Tejinder; Thakur, Ritula; Rana, Shakshi; Singh, Inderbir

    2017-08-15

    Heavy metal ions are non-biodegradable and contaminate most of the natural resources occurring in the environment including water. Some of the heavy metals including Lead (Pb), Mercury (Hg), Arsenic (As), Chromium (Cr) and Cadmium (Cd) are considered to be highly toxic and hazardous to human health even at trace levels. This leads to the requirement of fast, accurate and reliable techniques for the detection of heavy metal ions. This review presents various electrochemical detection techniques for heavy metal ions those are user friendly, low cost, provides on-site and real time monitoring as compared to other spectroscopic and optical techniques. The categorization of different electrochemical techniques is done on the basis of different types of detection signals generated due to presence of heavy metal ions in the solution matrix like current, potential, conductivity, electrochemical impedance, and electrochemiluminescence. Also, the recent trends in electrochemical detection of heavy metal ions with various types of sensing platforms including metals, metal films, metal oxides, nanomaterials, carbon nano tubes, polymers, microspheres and biomaterials have been evoked. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Nonlinear waves in electron–positron–ion plasmas including charge ...

    Indian Academy of Sciences (India)

    2017-01-04

    Jan 4, 2017 ... The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations. Keywords. Nonlinear waves; low frequency; ion-acoustic waves. PACS Nos 52.35.Qz; 52.35.Fp; 52.35 ...

  12. Ion mobility studies of carbohydrates as group I adducts: isomer specific collisional cross section dependence on metal ion radius.

    Science.gov (United States)

    Huang, Yuting; Dodds, Eric D

    2013-10-15

    Carbohydrates play numerous critical roles in biological systems. Characterization of oligosaccharide structures is essential to a complete understanding of their functions in biological processes; nevertheless, their structural determination remains challenging in part due to isomerism. Ion mobility spectrometry provides the means to resolve gas phase ions on the basis of their shape-to-charge ratios, thus providing significant potential for separation and differentiation of carbohydrate isomers. Here, we report on the determination of collisional cross sections for four groups of isomeric carbohydrates (including five isomeric disaccharides, four isomeric trisaccharides, two isomeric pentasaccharides, and two isomeric hexasaccharides) as their group I metal ion adducts (i.e., [M + Li](+), [M + Na](+), [M + K](+), [M + Rb](+), and [M + Cs](+)). In all, 65 collisional cross sections were measured, the great majority of which have not been previously reported. As anticipated, the collisional cross sections of the carbohydrate metal ion adducts generally increase with increasing metal ion radius; however, the collisional cross sections were found to scale with the group I cation size in isomer specific manners. Such measurements are of substantial analytical value, as they illustrate how the selection of charge carrier influences carbohydrate ion mobility determinations. For example, certain pairs of isomeric carbohydrates assume unique collisional cross sections upon binding one metal ion, but not another. On the whole, these data suggest a role for the charge carrier as a probe of carbohydrate structure and thus have significant implications for the continued development and application of ion mobility spectrometry for the distinction and resolution of isomeric carbohydrates.

  13. Sorption of Molecular Oxygen by Metal-Ion Exchanger Nanocomposites

    Science.gov (United States)

    Krysanov, V. A.; Plotnikova, N. V.; Kravchenko, T. A.

    2018-03-01

    Kinetic features are studied of the chemisorption and reduction of molecular oxygen from water by metal-ion exchanger nanocomposites that differ in the nature of the dispersed metal and state of oxidation. In the Pd equilibrium sorption coefficient for oxygen dissolved in water ranges from 20 to 50, depending on the nature and oxidation state of the metal component.

  14. A Selective Bioreduction of Toxic Heavy Metal Ions from Aquatic Environment by Saccharomyces cerevisiae

    OpenAIRE

    Rahatgaonkar, A. M.; Mahore, N. R.

    2008-01-01

    The need to remove or recover metal ions from industrial wastewater has been established in financial as well as environmental terms. This need has been proved financially in terms of cost saving through metal reuse or sale and environmentally as heavy metal toxicity can affect organisms throughout the food chain, including humans. Bioremediation of heavy metal pollution remains a major challenge in environmental biotechnology. Current removal strategies are mainly based on bioreduction of Co...

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

    Science.gov (United States)

    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.

  16. Study on 'Tannix' an absorbent for heavy metals including uranium

    International Nuclear Information System (INIS)

    Nakamura, Yasuo

    1997-01-01

    To treat radioactive wastes including uranium and transuranic elements such as plutonium, americium etc., development of an absorbent which can be used to absorb and isolate these elements without producing secondary wastes after treatment was attempted. And an absorbent has been successfully developed by polymerizing tannin, a natural product. It is known that tannin binds heavy metals including uranium resulting to produce their precipitates. There are some reports suggesting its absorption ability for uranium. However, tannin has not been used to isolate a heavy metal from a solution because it is soluble in water. Here, insolubilization of tannin was attempted and a manufacturing method for a gelatinized insoluble tannin named as ''Tannix'' was established. Wattle tannin extracted from Mimosa pudica produced in Africa was dissolved in an alkaline solution and gelatinized by heating after the addition of formalin. Thus obtained insoluble tannin was used after crushing and sieving. This product, ''Tannix'' was able to absorb more than 99% of uranium in the waste. And the absorbed Tannin could be degraded by incineration even at a low temperature, leaving only uranium, but not producing any secondary product. (M.N.)

  17. Study on `Tannix` an absorbent for heavy metals including uranium

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yasuo [Mitsubishi Nuclear Fuel Co. Ltd., Tokyo (Japan)

    1997-09-01

    To treat radioactive wastes including uranium and transuranic elements such as plutonium, americium etc., development of an absorbent which can be used to absorb and isolate these elements without producing secondary wastes after treatment was attempted. And an absorbent has been successfully developed by polymerizing tannin, a natural product. It is known that tannin binds heavy metals including uranium resulting to produce their precipitates. There are some reports suggesting its absorption ability for uranium. However, tannin has not been used to isolate a heavy metal from a solution because it is soluble in water. Here, insolubilization of tannin was attempted and a manufacturing method for a gelatinized insoluble tannin named as ``Tannix`` was established. Wattle tannin extracted from Mimosa pudica produced in Africa was dissolved in an alkaline solution and gelatinized by heating after the addition of formalin. Thus obtained insoluble tannin was used after crushing and sieving. This product, ``Tannix`` was able to absorb more than 99% of uranium in the waste. And the absorbed Tannin could be degraded by incineration even at a low temperature, leaving only uranium, but not producing any secondary product. (M.N.)

  18. Initiation of protein association in tofu formation by metal ions.

    Science.gov (United States)

    Arii, Yasuhiro; Takenaka, Yasuyuki

    2014-01-01

    Magnesium and calcium ions are important factors in making tofu. However, the molecular role of these ions remains unclear in tofu formation. We have previously shown that magnesium chloride concentration-dependent produced silken tofu-like (SP) and regular tofu-like (RP) precipitates, but was an inconsequential factor for the retention of tofu. We investigated in this present study, the effect of various metal chlorides on the metal chloride concentration-dependent changes in tofu formation. These changes occurred in a similar manner to that of the magnesium ion, in which SP formation was followed by RP formation. It is interesting that the midpoint concentration for the formation of SP and RP represented a good correlation with the stability constant of EDTA. This correlation demonstrated the possibility that metal ions would interact with the carboxyl groups of soy proteins. We consider from these results that metal ions were the initiators of protein association in tofu formation.

  19. Porous Poly(Ionic Liquid) Membranes as Efficient and Recyclable Absorbents for Heavy Metal Ions.

    Science.gov (United States)

    Ren, Yongyuan; Zhang, Jiandong; Guo, Jiangna; Chen, Fei; Yan, Feng

    2017-07-01

    Heavy metal ion pollution has become a serious environmental problem. Herein, this study reports the synthesis of poly(ionic liquid) (PIL) membranes via in situ photo-crosslinking of vinyl imidazole with both hydrophilic and hydrophobic ionic liquid monomers. The resultant amphiphilic polymer membranes are porous and exhibit high absorption capacity of metal ions (including Hg 2+ , Pb 2+ , Cu 2+ , Cd 2+ , and Zn 2+ ) in both high (1000 mg L -1 ) and low (10 mg L -1 ) concentration metal ion solutions. These metal ionic absorption membranes are easily regenerated in acid solution and can be reused without significant decreases of absorption capacity after many cycles. These PIL membranes may have potential applications as eco-friendly and safe heavy metal ion removal materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    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.

  1. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    Bond, A. H.

    1998-01-01

    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

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

    Science.gov (United States)

    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. 2010 Elsevier B.V. All rights reserved.

  5. Catalytic metal ions and enzymatic processing of DNA and RNA.

    Science.gov (United States)

    Palermo, Giulia; Cavalli, Andrea; Klein, Michael L; Alfonso-Prieto, Mercedes; Dal Peraro, Matteo; De Vivo, Marco

    2015-02-17

    CONSPECTUS: Two-metal-ion-dependent nucleases cleave the phosphodiester bonds of nucleic acids via the two-metal-ion (2M) mechanism. Several high-resolution X-ray structures portraying the two-metal-aided catalytic site, together with mutagenesis and kinetics studies, have demonstrated a functional role of the ions for catalysis in numerous metallonucleases. Overall, the experimental data confirm the general mechanistic hypothesis for 2M-aided phosphoryl transfer originally reported by Steitz and Steitz ( Proc. Natl. Acad. Sci. U.S.A. 1993 , 90 ( 14 ), 6498 - 6502 ). This seminal paper proposed that one metal ion favors the formation of the nucleophile, while the nearby second metal ion facilitates leaving group departure during RNA hydrolysis. Both metals were suggested to stabilize the enzymatic transition state. Nevertheless, static X-ray structures alone cannot exhaustively unravel how the two ions execute their functional role along the enzymatic reaction during processing of DNA or RNA strands when moving from reactants to products, passing through metastable intermediates and high-energy transition states. In this Account, we discuss the role of multiscale molecular simulations in further disclosing mechanistic insights of 2M-aided catalysis for two prototypical enzymatic targets for drug discovery, namely, ribonuclease H (RNase H) and type II topoisomerase (topoII). In both examples, first-principles molecular simulations, integrated with structural data, emphasize a cooperative motion of the bimetal motif during catalysis. The coordinated motion of both ions is crucial for maintaining a flexible metal-centered structural architecture exquisitely tailored to accommodate the DNA or RNA sugar-phosphate backbone during phosphodiester bond cleavage. Furthermore, our analysis of RNase H and the N-terminal domain (PAN) of influenza polymerase shows that classical molecular dynamics simulations coupled with enhanced sampling techniques have contributed to describe

  6. Designer ligands: The search for metal ion selectivity

    Directory of Open Access Journals (Sweden)

    Perry T. Kaye

    2011-03-01

    Full Text Available The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang, E-mail: hdeng@whu.edu.cn

    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.

  8. Extraction of complexes of metal ions with pyridine oxyazo compounds

    International Nuclear Information System (INIS)

    Lobanov, F.I.; Nurtaeva, G.K.; Ergozhin, E.E.

    1983-01-01

    Modern state and prospects of the development of investigas tions in the field of extraction of complexes of metal ions (V, In, Cd, Nb, REE, RU, Ta, U, Zr and others) with pyridine oxyazo compoUnds are analyzed. Application of pyridine oxyazo compounds as extraction-photometric reagents is described. Basic methods of oxyazo compounds preparation are considered along with reagent properties and physical-chemical characteristics. Flow diagrams of ion extraction are presented for the above metals. Mechanisms of complexing reactions for metal ions with pyridine oxyazo compounds and stability of forming complexes are considered in detail. Concrete methods of extraction-photometric separation and element determination permitting to find simultaneously several metal ions with similar properties in the case of their joint presence are described

  9. Determination of Heavy Metal Ions in Tobacco and Tobacco Additives

    African Journals Online (AJOL)

    NJD

    aminophenyl)-porphyrin, heavy metal ions. 1. Introduction ..... Application. This method was applied to the determination of Co, Ni, Sn,. Hg, Pb and Cd in the glycerol, tobacco leaf, tobacco sauce and cigarette samples. The samples were prepared ...

  10. Adhesive, abrasive and oxidative wear in ion-implanted metals

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1985-01-01

    Ion implantation is increasingly being used to provide wear resistance in metals and cemented tungsten carbides. Field trials and laboratory tests indicate that the best performance is achieved in mild abrasive wear. This can be understood in terms of the classification of wear modes (adhesive, abrasive, oxidative etc.) introduced by Burwell. Surface hardening and work hardenability are the major properties to be enhanced by ion implantation. The implantation of nitrogen or dual implants of metallic and interstitial species are effective. Recently developed techniques of ion-beam-enhanced deposition of coatings can further improve wear resistance by lessening adhesion and oxidation. In order to support such hard coatings, ion implantation of nitrogen can be used as a preliminary treatment. There is thus emerging a versatile group of related hard vacuum treatments involving intense beams of nitrogen ions for the purpose of tailoring metal surfaces to resist wear. (Auth.)

  11. Metal Ion Selectivity of Kojate Complexes: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Sarita Singh

    2013-01-01

    Full Text Available Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

  12. A versatile MOF-based trap for heavy metal ion capture and dispersion

    OpenAIRE

    Peng, Yaguang; Huang, Hongliang; Zhang, Yuxi; Kang, Chufan; Chen, Shuangming; Song, Li; Liu, Dahuan; Zhong, Chongli

    2018-01-01

    Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, ...

  13. Liquid metal field-emission ion sources and their applications

    International Nuclear Information System (INIS)

    Prewett, P.D.; Jefferies, D.K.

    1980-01-01

    The study of ion emission from liquid metal surfaces under the action of high electric fields has led to the development of ion sources of exceptionally high brightness. The design and operating characteristics of commercially manufactured sources of gallium and gold ions are described. Preliminary focusing and scanning experiments have produced spots estimated to be approximately 0.5 μm diameter at currents approximately 0.2 nA using an electrostatic ion optical system. A focused Ga + beam has been used as an ion microprobe for imaging and for elemental mapping of surfaces by SIMS. (author)

  14. [Detection of metal ions in hair after metal-metal hip arthroplasty].

    Science.gov (United States)

    Hernandez-Vaquero, D; Rodríguez de la Flor, M; Fernandez-Carreira, J M; Sariego-Muñiz, C

    2014-01-01

    There is an increase in the levels of metals in the serum and urine after the implantation of some models of metal-metal hip prosthesis. It has recently been demonstrated that there is an association between these levels and the levels found in hair. The aim of this study is to determine the presence of metals in hair, and to find out whether these change over time or with the removal of the implant. The levels of chromium, cobalt and molybdenum were determined in the hair of 45 patients at 3, 4, 5, and 6 years after a hip surface replacement. The mean age was 57.5 years, and two were female. Further surgery was required to remove the replacement and implant a new model with metal-polyethylene friction in 11 patients, 5 of them due to metallosis and a periarticular cyst. The mean levels of metals in hair were chromium 163.27 ppm, cobalt 61.98 ppm, and molybdenum 31.36 ppm, much higher than the levels found in the general population. A decrease in the levels of chromium (43.8%), molybdenum (51.1%), and cobalt (91.1%) was observed at one year in the patients who had further surgery to remove the prosthesis. High concentrations of metals in the hair are observed in hip replacements with metal-metal friction, which decrease when that implant is removed. The determination of metal ions in hair could be a good marker of the metal poisoning that occurs in these arthroplasty models. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  15. Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

    Directory of Open Access Journals (Sweden)

    Qingqing Wang

    2014-09-01

    Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

  16. Enhancement of metal bioleaching from contaminated sediment using silver ion.

    Science.gov (United States)

    Chen, Shen-Yi; Lin, Jih-Gaw

    2009-01-30

    A silver-catalyzed bioleaching process was used to remove heavy metals from contaminated sediment in this study. The effects of silver concentration added on the performance of bioleaching process were investigated. High pH reduction rate was observed in the bioleaching process with silver ion. The silver ion added in the bioleaching process was incorporated into the lattice of the initial sulfide through a cationic interchange reaction. This resulted in the short lag phase and high metal solubilization in the bioleaching process. The maximum pH reduction rate and the ideal metal solubilization were obtained in the presence of 30 mg/L of silver ion. When the added silver ion was greater than 30 mg/L, the rates of pH reduction and metal solubilization gradually decreased. The solubilization efficiencies of heavy metals (Cu, Zn, Mn, Ni and Cr) were relatively high in the silver-enhanced bioleaching process, except Pb. No apparent effect of silver ion on the growth of sulfur-oxidizing bacteria was found in the bioleaching. These results indicate that the kinetics of metal solubilization can be enhanced by the addition of silver ion.

  17. Cooperative adsorption of critical metal ions using archaeal poly-γ-glutamate.

    Science.gov (United States)

    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.

  18. A 1-dodecanethiol-based phase transfer protocol for the highly efficient extraction of noble metal ions from aqueous phase.

    Science.gov (United States)

    Chen, Dong; Cui, Penglei; Cao, Hongbin; Yang, Jun

    2015-03-01

    A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an ethanolic solution of 1-dodecanethiol, and then extracting the coordination compounds formed between noble metal ions and 1-dodecanethiol into a non-polar organic solvent. A number of characterization techniques, including inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis demonstrate that this protocol could be applied to extract a wide variety of noble metal ions from water to dichloromethane with an efficiency of >96%, and has high selectivity for the separation of the noble metal ions from other transition metals. It is therefore an attractive alternative for the extraction of noble metals from water, soil, or waste printed circuit boards. Copyright © 2015. Published by Elsevier B.V.

  19. Chemical Speciation of Some metal ions in Groundwaters of Yola ...

    African Journals Online (AJOL)

    Chemical speciation of some metal ions in groundwaters of Yola area using geochemical model were carried out to determine the water quality of the area using the PHREEQC speciation model. The study findings based on model calculations indicated that free Na+, Ca2+, Mg2+ and K+ ions are present and the ...

  20. Electrical properties of polymer modified by metal ion implantation

    International Nuclear Information System (INIS)

    Wu Yuguang; Zhang Tonghe; Zhang Huixing; Zhang Xiaoji; Deng Zhiwei; Zhou Gu

    2000-01-01

    Polyethylene terephthalate (PET) has been modified by Ag, Cr, Cu and Si ion implantation with a dose range from 1x10 16 to 2x10 17 ions cm -2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been changed after metal ion implantation. The resistivity of implanted PET decreased obviously with an increase of ion dose. When metal ion dose of 2x10 17 cm -2 was selected, the resistivity of PET could be less than 10 Ω cm, but when Si ions are implanted, the resistivity of PET would be up to several hundred Ω cm. The results show that the conductive behavior of a metal ion implanted sample is obviously different from Si implantation one. The changes of the structure and composition have been observed with transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface structure is varying after ion implantation and it is believed that the change would cause the improvement of the conductive properties. The mechanism of electrical conduction will be discussed

  1. Effect of ion beam irradiation on metal particle doped polymer ...

    Indian Academy of Sciences (India)

    that the surface roughness increases after ion beam irradiation. Keywords. Composite materials; ion beam irradiation; dielectric properties; X-ray diffraction. 1. Introduction. Various metal fillers were incorporated in polymers to pro- duce novel functionalized composites, which have found extensive applications, such as ...

  2. The kinetics and thermodynamics of adsorption of heavy metal ions ...

    African Journals Online (AJOL)

    Titanium-Pillared and Un-Pillared bentonite clays were studied in order to evaluate the thermodynamics and kinetics of heavy metal ion removal from aqueous solutions. The results showed that the maximum sorption of Cu, Cd, Hg and Pb ions occurred within 30 minutes. A pseudo-second order kinetic model was used to ...

  3. Sorption of toxic metal ions in aqueous environment using ...

    African Journals Online (AJOL)

    2012-03-08

    Mar 8, 2012 ... efficient sorbents for divalent heavy metal ions in aqueous environments as their efficiencies exceeded those of chitosan microspheres, ion-imprinted composites, ..... field strength of 1.67 kV/cm. Under these optimised condi- ..... extraction on modified multiwalled carbon nanotubes. Cent. Eur. J. Chem.

  4. Quantum ion-acoustic wave oscillations in metallic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah, Iran and Department of Nano Sciences, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

    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.

  5. Two-photon-induced reduction of metal ions for fabricating three-dimensional electrically conductive metallic microstructure

    Science.gov (United States)

    Tanaka, Takuo; Ishikawa, Atsushi; Kawata, Satoshi

    2006-02-01

    We developed techniques for fabricating three-dimensional metallic microstructures using two-photon-induced metal-ion reduction. In this process, ions in a metal-ion aqueous solution were directly reduced by a tightly focused femtosecond pulsed laser to fabricate arbitrary three-dimensional structures. A self-standing metallic microstructure with high electrical conductivity was demonstrated.

  6. Metal ion sorption by untreated and chemically treated biomass

    Energy Technology Data Exchange (ETDEWEB)

    Kilbane, J.J.; Xie, J.

    1992-12-31

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

  7. DETERMINATION OF METAL IONS RELEASED BY STAINLESS ...

    African Journals Online (AJOL)

    The amounts of cobalt, iron, manganese, nickel and chromium ions released from new and reused stainless steel arch bar used for maxillomandibular fixation was determined in Hank's solutions of different hydrogen and chloride ions concentrations, whole blood serum and phosphate buffered saline (PBS) in vitro, over a ...

  8. Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon.

    Science.gov (United States)

    Choi, Moonjung; Jang, Jyongsik

    2008-09-01

    Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group of polypyrrole. The introduced polypyrrole layer could provide the surface modification to be applied for heavy metal ion adsorbents. Especially, polymer-impregnated porous carbon has an enhanced heavy metal ion uptake, which is 20 times higher than that of adsorbents with amine functional groups. Furthermore, the relationship between the coated polymer amount and surface area was also investigated in regard to adsorption capacity.

  9. Investigation of metal ions sorption of brown peat moss powder

    Science.gov (United States)

    Kelus, Nadezhda; Blokhina, Elena; Novikov, Dmitry; Novikova, Yaroslavna; Chuchalin, Vladimir

    2017-11-01

    For regularities research of sorptive extraction of heavy metal ions by cellulose and its derivates from aquatic solution of electrolytes it is necessary to find possible mechanism of sorption process and to choice a model describing this process. The present article investigates the regularities of aliovalent metals sorption on brown peat moss powder. The results show that sorption isotherm of Al3+ ions is described by Freundlich isotherm and sorption isotherms of Na+ i Ni2+ are described by Langmuir isotherm. To identify the mechanisms of brown peat moss powder sorption the IR-spectra of the initial brown peat moss powder samples and brown peat moss powder samples after Ni (II) sorption were studied. Metal ion binding mechanisms by brown peat moss powder points to ion exchange, physical adsorption, and complex formation with hydroxyl and carboxyl groups.

  10. Accumulation of some metal ions on Bacillus licheniformis

    International Nuclear Information System (INIS)

    Hafez, M.B.; El-Desouky, W.; Fouad, A.

    2001-01-01

    Pure species of Bacillus licheniformis was used to remove ions from aqueous and simulated waste solutions. Metal ion accumulation on B. licheniformis was fast. Maximum uptake occurred at pH 4± 0.5 and at 25 ± 3 deg C. One gram of dry B. licheniformis was found to accumulate 115 mg cerium, 34 mg copper and 11 mg cobalt from aqueous solutions. The presence of certain foreign ions such as calcium, sodium and potassium decreased the uptake of ions by B. licheniformis, while citrate and EDTA prevent the uptake. Electron microscopic investigations showed that cerium (III), copper (II) and cobalt (II) accumulated extracellulary around the surface wall of B. licheniformis cells. A bio-adsorption mechanism between the metal ions and B. licheniformis cell wall was proposed. (author)

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Complexation ion-exchange chromatography of some metal ions on papers impregnated with Ti(IV)-based inorganic ion exchangers.

    Science.gov (United States)

    Sharma, S D; Gupta, R

    2000-02-01

    The chromatographic behavior of 40 metal ions is studied on titanium (IV) arsenate, titanium (IV) phosphate-, titanium (IV) molybdate-, titanium(IV) tungstate-, and titanium(IV) selenite-impregnated papers in 0.1M oxalic, citric, and tartaric acid as mobile phases. Similar studies are carried out on Whatman No. 1 papers for comparison. The ion-exchange capacity of these papers is determined, and their selectivity for different cations is discussed. The mechanism of migration is explained in terms of ion-exchange, precipitation, and adsorption. The prediction of elution sequence from RF values is also checked. The average Ri is found to be almost linearly dependent on the charge of the metal ions. The effect of the pKa of complexing acids on average RF values of 3d series metal ions is explained. A number of binary and ternary separations are achieved.

  13. Adsorption of heavy metal ions by sawdust of deciduous trees.

    Science.gov (United States)

    Bozić, D; Stanković, V; Gorgievski, M; Bogdanović, G; Kovacević, R

    2009-11-15

    The adsorption of heavy metal ions from synthetic solutions was performed using sawdust of beech, linden and poplar trees. The adsorption depends on the process time, pH of the solution, type of ions, initial concentration of metals and the sawdust concentration in suspension. The kinetics of adsorption was relatively fast, reaching equilibrium for less than 20 min. The adsorption equilibrium follows Langmuir adsorption model. The ion exchange mechanism was confirmed assuming that the alkali-earth metals from the adsorbent are substituted by heavy metal ions and protons. On lowering the initial pH, the adsorption capacity decreased, achieving a zero value at a pH close to unity. The maximum adsorption capacity (7-8 mg g(-1) of sawdust) was achieved at a pH between 3.5 and 5 for all the studied kinds of sawdust. The initial concentration of the adsorbate and the concentration of sawdust strongly affect the process. No influence of particles size was evidenced. A degree of adsorption higher than 80% can be achieved for Cu(2+) ions but it is very low for Fe(2+) ions, not exceeding 10%.

  14. Adsorption of heavy metal ions by sawdust of deciduous trees

    International Nuclear Information System (INIS)

    Bozic, D.; Stankovic, V.; Gorgievski, M.; Bogdanovic, G.; Kovacevic, R.

    2009-01-01

    The adsorption of heavy metal ions from synthetic solutions was performed using sawdust of beech, linden and poplar trees. The adsorption depends on the process time, pH of the solution, type of ions, initial concentration of metals and the sawdust concentration in suspension. The kinetics of adsorption was relatively fast, reaching equilibrium for less than 20 min. The adsorption equilibrium follows Langmuir adsorption model. The ion exchange mechanism was confirmed assuming that the alkali-earth metals from the adsorbent are substituted by heavy metal ions and protons. On lowering the initial pH, the adsorption capacity decreased, achieving a zero value at a pH close to unity. The maximum adsorption capacity (7-8 mg g -1 of sawdust) was achieved at a pH between 3.5 and 5 for all the studied kinds of sawdust. The initial concentration of the adsorbate and the concentration of sawdust strongly affect the process. No influence of particles size was evidenced. A degree of adsorption higher than 80% can be achieved for Cu 2+ ions but it is very low for Fe 2+ ions, not exceeding 10%.

  15. Ion conducting fluoropolymer carbonates for alkali metal ion batteries

    Science.gov (United States)

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Balsara, Nitash P.; Thelen, Jacob; Devaux, Didier

    2017-09-05

    Liquid or solid electrolyte compositions are described that comprise a homogeneous solvent system and an alkali metal salt dissolved in said solvent system. The solvent system may comprise a fluoropolymer, having one or two terminal carbonate groups covalently coupled thereto. Batteries containing such electrolyte compositions are also described.

  16. Sono-electrochemical recovery of metal ions from their aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Bingfeng; Fishgold, Asher [Department of Materials Science and Engineering, The University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Lee, Paul [Department of Chemistry and Biochemistry, The University of Arizona, 1306 E. University Blvd, Tucson, AZ 85721 (United States); Runge, Keith; Deymier, Pierre [Department of Materials Science and Engineering, The University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Keswani, Manish, E-mail: manishk@email.arizona.edu [Department of Materials Science and Engineering, The University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ 85721 (United States)

    2016-11-15

    Highlights: • Sono-electrochemical method is effective in the recovery of Pd, Ga and Pb. • Recovery efficiency depends on the type of metal ion and megasonic frequency used. • Pd is recovered mainly in metallic form while Ga and Pb show presence of oxide. - Abstract: Metal recovery from aqueous waste streams is an important goal for recycling, agriculture and mining industries. The development of more effective methods of recovery have been of increasing interest. The most common methods for metal recovery include precipitation, electrochemical, ion exchange, flocculation/coagulation and filtration. In the current work, a sono-electrochemical technique employing sound field at megasonic frequency (500 kHz or 1 MHz) in conjunction with electrochemistry is evaluated for enhanced recovery of selected metal ions (palladium, lead and gallium) with different redox potentials from their aqueous solutions. The surface morphology and elemental composition of the metal deposits were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The percent recovery was found to depend on the type of metal ion and the megasonic frequency used. Palladium was recovered in its metal form, while lead and gallium were oxidized during or after the recovery process.

  17. Metal ion mediated photolysis reactions of riboflavin: A kinetic study.

    Science.gov (United States)

    Ahmad, Iqbal; Anwar, Zubair; Ahmed, Sofia; Sheraz, Muhammad Ali; Khattak, Saif-Ur-Rehman

    2017-08-01

    The effect of metal ion complexation on the photolysis of riboflavin (RF) using various metal ions (Ag + , Ni 2+ , Co 2+ , Fe 2+ , Ca 2+ , Cd 2+ , Cu 2+ , Mn 2+ , Pb 2+ , Mg 2+ , Zn 2+ , Fe 3+ ) has been studied. Ultraviolet and visible spectral and fluorimetric evidence has been obtained to confirm the formation of metal-RF complexes. The kinetics of photolysis of RF in metal-RF complexes at pH7.0 has been evaluated. The apparent first-order rate constant (k obs ) for the photolysis of RF and the formation of lumichrome (LC) and lumiflavin (LF) (0.001M phosphate buffer) and LC, LF and cyclodehydroriboflavin (CDRF) (0.2-0.4M phosphate buffer) have been determined. The values of k obs indicate that the rate of photolysis of RF is promoted by divalent and trivalent metal ions. The second-order rate constants (k' ) for the interaction of metal ions with RF are in the order: Zn 2+ >Mg 2+ >Pb 2+ >Mn 2+ >Cu 2+ >Cd 2+ >Fe 2+ >Ca 2+ >Fe 3+ >Co 2+ >Ni 2+ >Ag + . In phosphate buffer (0.2-0.4M), an increase in the metal ion concentration leads to a decrease in the formation of LC compared to that of CDRF by different pathways. The photoproducts of RF have been identified and RF and the photoproducts have simultaneously been assayed by a multicomponent spectrometric method. The mode of photolysis of RF in metal-RF complexes has been discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    KAUST Repository

    Zhang, Weipeng

    2013-11-11

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

  19. Hydrometallurgical recovery of metal values by the use of ion exchange

    International Nuclear Information System (INIS)

    Higgins, I.R.

    1982-01-01

    This paper presented what had been accomplished to date using Packed Bed Continuous Countercurrent Ion Exchange (CCIX) and proposed plans for more comprehensive systems that include many soluble metals of value. Frontiers of hydrometallurgy cannot be breached until advantage is taken of a multitude of metal ions in solution. The future utilization of hydrometallurgical methodology depends on the success of extraction and separation unit operations and being accepted by mining companies. Examples are presented of CCIX projects in operation and pilot plants tested as proof of the special attractive features of the Chem-Seps CCIX system. An overall plan was presented for processing of sulfide type mineralization, with emphasis on making an effort to get ''complete'' dissolution of all metals of value. Continuous Countercurrent Ion Exchange plays a vital role in hydrometallurical processing because of the need to handle prodigious volumes of solution, tremendous tonnages of salts, and to compensate for poor ion exchange equilibrium. 11 figures. (DP)

  20. Ion beam modification of metals: Compositional and microstructural changes

    Science.gov (United States)

    Was, Gary S.

    Ion implantation has become a highly developed tool for modifying the structure and properties of metals and alloys. In addition to direct implantation, a variety of other ion beam techniques such as ion beam mixing, ion beam assisted deposition and plasma source ion implantation have been used increasingly in recent years. The modifications constitute compositional and microstructural changes in the surface of the metal. This leads to alterations in physical properties (transport, optical, corrosion, oxidation), as well as mechanical properties (strength, hardness, wear resistance, fatigue resistance). The compositional changes brought about by ion bombardment are classified into recoil implantation, cascade mixing, radiation-enhanced diffusion, radiation-induced segregation, Gibbsian adsorption and sputtering which combine to produce an often complicated compositional variation within the implanted layer and often, well beyond. Microstructurally, the phases present are often altered from what is expected from equilibrium thermodynamics giving rise to order-disorder transformations, metastable (crystalline, amorphous or quasicrystalline) phase formation and growth, as well as densification, grain growth, formation of a preferred texture and the formation of a high density dislocation network. All these effects need to be understood before one can determine the effect of ion bombardment on the physical and mechanical properties of metals. This paper reviews the literature in terms of the compositional and microstructural changes induced by ion bombardment, whether by direct implantation, ion beam mixing or other forms of ion irradiation. The topics are introduced as well as reviewed, making this a more pedogogical approach as opposed to one which treats only recent developments. The aim is to provide the tools needed to understand the consequent changes in physical and mechanical properties.

  1. COMPARATIVE STUDY ON METAL IONS ADSORPTION ON A LOW COST CARBONACEOUS ADSORBENT KINETIC EQUILIBRIUM AND MECHANISTIC STUDIES

    OpenAIRE

    S. Arivoli, M. Hema, C. Barathiraja

    2008-01-01

    A carbonaceous adsorbent prepared from an indigenous waste and treated by acid was tested for its efficiency in removing metal ions of Fe(II), Co(II) and Ni(II). The process parameters studied included agitation time, initial metal ion concentration, carbon dosage, pH, other ions and temperature. The kinetics of adsorption followed first order reaction equation and the rate was mainly controlled by intraparticle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibriu...

  2. Complementary metal ion specificity of the metal-citrate transporters CitM and CitH of Bacillus subtilis

    NARCIS (Netherlands)

    Krom, BP; Warner, JB; Konings, WN; Lolkema, JS; Warner, Jessica B.

    2000-01-01

    Citrate uptake in Bacillus subtilis is stimulated by a wide range of divalent metal ions. The metal ions were separated into two groups based on the expression pattern of the uptake system. The two groups correlated with the metal ion specificity of two homologous B, subtilis secondary citrate

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

    Science.gov (United States)

    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.

  4. A possible role of alkali metal ions in the synthesis of pure-silica molecular sieves

    OpenAIRE

    Goepper, Michelle; Li, Hong-Xin; Davis, Mark E.

    1992-01-01

    Pure-silica ZSM-12 is synthesized in the presence and absence of alkali metal ions; addition of alkali metal ions at constant hydroxide ion concentration increases the crystallization rate of ZSM-12, and it is suggested that alkali metal ions participate in both the nucleation and crystal growth processes.

  5. Radiation hardening of metals irradiated by heavy ions

    International Nuclear Information System (INIS)

    Didyk, A.Yu.; Skuratov, V.A.; Mikhajlova, N.Yu.; Regel', V.R.

    1988-01-01

    The damage dose dependence in the 10 -4 -10 -2 dpa region of radiation hardening of Al, V, Ni, Cu irradiated by xenon ions with 124 MeV energy is investigated using the microhardness technique and transmission electron microscope. It is shown that the pure metals radiation hardening is stimulated for defects clusters with the typical size less than 5 nm, as in the case of neutron and the light charge ion irradiation

  6. Metal ion effects on enolase activity

    International Nuclear Information System (INIS)

    Lee, M.E.; Nowak, T.

    1986-01-01

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

  7. Plasmon modes of metallic nanowires including quantum nonlocal effects

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah, Iran and Department of Nano Sciences, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

    2015-03-15

    The properties of electrostatic surface and bulk plasmon modes of cylindrical metallic nanowires are investigated, using the quantum hydrodynamic theory of plasmon excitation which allows an analytical study of quantum tunneling effects through the Bohm potential term. New dispersion relations are obtained for each type of mode and their differences with previous treatments based on the standard hydrodynamic model are analyzed in detail. Numerical results show by considering the quantum effects, as the value of wave number increases, the surface modes are slightly red-shifted first and then blue-shifted while the bulk modes are blue-shifted.

  8. A versatile MOF-based trap for heavy metal ion capture and dispersion.

    Science.gov (United States)

    Peng, Yaguang; Huang, Hongliang; Zhang, Yuxi; Kang, Chufan; Chen, Shuangming; Song, Li; Liu, Dahuan; Zhong, Chongli

    2018-01-15

    Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd 2+ -loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.

  9. Crystal structures of Dronpa complexed with quenchable metal ions provide insight into metal biosensor development.

    Science.gov (United States)

    Kim, In Jung; Kim, Sangsoo; Park, Jeahyun; Eom, Intae; Kim, Sunam; Kim, Jin-Hong; Ha, Sung Chul; Kim, Yeon Gil; Hwang, Kwang Yeon; Nam, Ki Hyun

    2016-09-01

    Many fluorescent proteins (FPs) show fluorescence quenching by specific metal ions, which can be applied towards metal biosensor development. In this study, we investigated the significant fluorescence quenching of Dronpa by Co(2+) and Cu(2+) ions. Crystal structures of Co(2+) -, Ni(2+) - and Cu(2+) -bound Dronpa revealed previously unseen, unique, metal-binding sites for fluorescence quenching. These metal ions commonly interact with surface-exposed histidine residues (His194-His210 and His210-His212), and interact indirectly with chromophores. Structural analysis of the Co(2+) - and Cu(2+) - binding sites of Dronpa provides insight into FP-based metal biosensor engineering. © 2016 Federation of European Biochemical Societies.

  10. Functionalization of protein crystals with metal ions, complexes and nanoparticles.

    Science.gov (United States)

    Abe, Satoshi; Maity, Basudev; Ueno, Takafumi

    2018-04-01

    Self-assembled proteins have specific functions in biology. With inspiration provided by natural protein systems, several artificial protein assemblies have been constructed via site-specific mutations or metal coordination, which have important applications in catalysis, material and bio-supramolecular chemistry. Similar to natural protein assemblies, protein crystals have been recognized as protein assemblies formed of densely-packed monomeric proteins. Protein crystals can be functionalized with metal ions, metal complexes or nanoparticles via soaking, co-crystallization, creating new metal binding sites by site-specific mutations. The field of protein crystal engineering with metal coordination is relatively new and has gained considerable attention for developing solid biomaterials as well as structural investigations of enzymatic reactions, growth of nanoparticles and catalysis. This review highlights recent and significant research on functionalization of protein crystals with metal coordination and future prospects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Focused ion beam lithography for rapid prototyping of metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Osswald, Patrick; Kiermaier, Josef; Becherer, Markus; Schmitt-Landsiedel, Doris [Lehrstuhl fuer Technische Elektronik, TU Muenchen, Munich (Germany)

    2010-07-01

    We present FIB-lithography methods for rapid and cost-effective prototyping of metal structures covering the deep-submicron- to the millimeter-range in a single lithography cycle. Focused ion beam (FIB) systems are widely used in semiconductor industry and research facilities for both analytical testing and prototyping. A typical application is to apply electrical contact to micron-sized sensors/particles by FIB induced metal deposition. However, as for E-beam lithography, patterning times for large area bonding pads are unacceptably long, resulting in cost-intensive prototyping. In this work, we optimized FIB lithography processing for negative and positive imaging mode to form metallic structures for large-areas down do the sub-100 nm range. For negative lithography features are defined by implanting Ga{sup +}-ions into a commercial photo resist, without affecting the underlying structures by impinging ions. The structures are highly suitable for following lift-off processing due to the undercut of the resist.Metallic feature size of down to 150 nm are achievable. For positive lithography a PMMA resist is exposed in FIB irradiation. Due to the very low dose (3.10{sup 12} ions/cm{sup 2}) the writing time for an e.g. 100 {mu}m x 100 {mu}m square is approx. 15 seconds. The developed resist is used for subsequent wet chemical etching, obtaining a 100 nm resolution in metal layers.

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

    Science.gov (United States)

    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. Copyright 2010 Elsevier Inc. All rights reserved.

  13. Albumin as marker for susceptibility to metal ions in metal-on-metal hip prosthesis patients.

    Science.gov (United States)

    Facchin, F; Catalani, S; Bianconi, E; Pasquale, D De; Stea, S; Toni, A; Canaider, S; Beraudi, A

    2017-04-01

    Metal-on-metal (MoM) hip prostheses are known to release chromium and cobalt (Co), which negatively affect the health status, leading to prosthesis explant. Albumin (ALB) is the main serum protein-binding divalent transition metals. Its binding capacity can be affected by gene mutations or modification of the protein N-terminal region, giving the ischaemia-modified albumin (IMA). This study evaluated ALB, at gene and protein level, as marker of individual susceptibility to Co in MoM patients, to understand whether it could be responsible for the different management of this ion. Co was measured in whole blood, serum and urine of 40 MoM patients. A mutational screening of ALB was performed to detect links between mutations and metal binding. Finally, serum concentration of total ALB and IMA were measured. Serum total ALB concentration was in the normal range for all patients. None of the subjects presented mutations in the investigated gene. Whole blood, serum and urine Co did not correlate with serum total ALB or IMA, although IMA was above the normal limit in most subjects. The individual susceptibility is very important for patients' health status. Despite the limited results of this study, we provide indications on possible future investigations on the toxicological response to Co.

  14. Adsorption of Metallic Ions onto Chitosan : Equilibrium and Kinetic Studies

    OpenAIRE

    Benavente, Martha

    2008-01-01

    Equilibrium isotherms and the adsorption kinetics of heavy metals onto chitosan were studied experimentally. Chitosan, a biopolymer produced from crustacean shells, has applications in various areas, particularly in drinking water and wastewater treatment due to its ability to remove metallic ions from solutions. The adsorption capacity of chitosan depends on a number of parameters: deacetylation degree, molecular weight, particle size and crystallinity. The purpose of this work was to study ...

  15. DETERMINATION OF METAL IONS RELEASED BY STAINLESS ...

    African Journals Online (AJOL)

    Preferred Customer

    Also taking into account the fact that, in body conditions implant corrosion products are disseminated and eventually eliminated. The result that SS arch bar used in orthodontic appliances corrode in bio-fluids over an extended time interval is of great clinical significance in evaluating their bio-compatibility, the levels of metal.

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

    Science.gov (United States)

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

    2008-09-01

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

  17. Sorption of heavy metal ions on new metal-ligand complexes chemically derived from Lycopodium clavatum

    Energy Technology Data Exchange (ETDEWEB)

    Pehlivan, E.; Ersoz, M.; Yildiz, S. [Univ. of Selcuk, Konya (Turkey); Duncan, H.J. [Univ. of Glasgow, Scotland (United Kingdom)

    1994-08-01

    Sorption of heavy metal ions from aqueous solution has been investigated as a function of pH using a novel exchanger system whereby Lycopodium clavatum is functionalized with carboxylate and glyoxime metal-ligand complexes. The new ligand exchangers were prepared using a reaction of diaminosporopollenin with various metal-ligand complexes of glyoxime and monocarboxylic acid. The sorptive behavior of these metal-ligand exchangers and the possibilities to remove and to recover selectively heavy metal cations using these systems are discussed on the basis of their chemical natures and their complexing properties.

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

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Adsorption of heavy metals ions on portulaca oleracea plants

    International Nuclear Information System (INIS)

    Naqvi, R.R.

    2005-01-01

    The aim of this study is to report the ability of portulaca oleracea (Fershi in Urdu) biomass grown in uncontaminated soils to adsorb or uptake lead, cadmium, arsenic, cobalt and copper from aqueous solutions. In order to help understand the metal binding mechanism, laboratory experiments performance to determine optimal binding, and binding capacity for each of the above mentioned metals. These experiments were carried out for the mass of crushed portulaca stems. Portulaca is a plant that grows abundantly in temperature climate in the area of Quetta Balochistan. It has reddish stem and thick succulent leaves. This plant has been found to be good adsorbent for heavy metals ions. (author)

  20. Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties

    DEFF Research Database (Denmark)

    Jantzen, Christopher; Jørgensen, Henrik L; Duus, Benn R

    2013-01-01

    Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties.......Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties....

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

    Directory of Open Access Journals (Sweden)

    Marc Dauplais

    Full Text Available 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.

  2. Effects of Alkali-Metal Ions and Counter Ions in Sn-Beta-Catalyzed Carbohydrate Conversion.

    Science.gov (United States)

    Elliot, Samuel G; Tolborg, Søren; Madsen, Robert; Taarning, Esben; Meier, Sebastian

    2018-02-26

    Alkali-metal ions have recently been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali-metal ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure and are herein addressed experimentally through kinetic experiments and isotope tracking. The presence of alkali-metal ions has a differential effect in competing reaction pathways and promotes the rate of carbon-carbon bond breakage of carbohydrate substrates, but decreases the rates of competing dehydration pathways. Further addition of alkali-metal ions inhibits the activity of Sn-Beta in all major reaction pathways. The alkali-metal effects on product distribution and on the rate of product formation are similar, thus pointing to a kinetic reaction control and to irreversible reaction steps in the main pathways. Additionally, an effect of the accompanying basic anions is shown, supposedly facilitating the cation exchange and eliciting a different concentration-dependent effect to that of neutral alkali-metal salts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Host Materials for Transition-Metal Ions

    Science.gov (United States)

    1989-09-01

    Phys. 5cr. 25 (1982), 924. J4. L. DiSiplo, E. Tondello, G. De~ichelis, and L. Oleari , Slater-Condon Parameters for Atoms and Ions of the Second...Bnm* Frequently, the point-charge crystal-field components, Anm, indicate the correct phase relations and are used to determine the phases reported in...745. 5. W. L. Bond, Measurement of the Refractive Indices of Several Crystals, J. Appl. Phys. 36 (1965), 1674. 6. G. Burns, E. A. Geiss, B. A

  4. Effect of sulphate and chloride ions on the solvent extraction of some metal ions with liquid cation exchangers

    International Nuclear Information System (INIS)

    Shibata, Junji; Nishimura, Sanji

    1977-01-01

    The extraction of the metal ions from sulphate and chloride solutions with Versatic Acid 911 and di(2-ethyl hexyl) phosphoric acid in benzene was investigated in order to clarify the effect of sulphate and chloride ions on the extraction. Sulphate and chloride ions are not extracted into the organic phase, and they affect metal extraction only by forming the complexes with metal ions in the aqueous phase. The extent of the effect on metal extraction is determined by the kind of metal ions and anionic ligands, and the concentration of ligand ions. Therefore, the difference in extraction behaviour may be explained by the complexing ability of the various anionic ligands present in the aqueous phase. Formation constants of the complexes between metal ions and anionic ligands were computed from these distribution data. (auth.)

  5. Interaction of Hydroxyproline with Bivalent Metal Ions in Chemical ...

    African Journals Online (AJOL)

    Arecent technique involving the use of paper electrophoresis is described for the study of equilibria in binary complex systems in solution. The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were determined in 0.1 mol L–1 perchloric acid ...

  6. Speciation and stability of methylene blue-metal-thiocyanate ion ...

    African Journals Online (AJOL)

    The relative stabilities indicate that cobalt is preferred to other two metals in the speciation of ternary complexes comparable with similar complexes in biosystems. This study also provides a method for the spectrophotometric determination of Co(II) and Zn(II) ions at nanogram levels at 25 oC and an ionic strength of 0.15 M.

  7. Synthesis, photophysical and metal ion signalling behaviour of mono

    Indian Academy of Sciences (India)

    Unknown

    Fluorescence decay behaviour of the systems suggests a through-space nature of PET. The systems exhi- bit off–on fluorescence signalling in the aprotic media in the presence of several metal ions, some of which are well known for their fluorescence quenching abilities. Diazacrown derivative, II, appears to be a somewhat ...

  8. Utilization of Plant Refuses as Component of Heavy Metal Ion ...

    African Journals Online (AJOL)

    The ability of the fabricated sensors to detect the presence of heavy metals was analyzed using electrochemical methods like cyclic voltammetry and differential pulse anodic stripping voltammetry. Results showed that the fabricated electrode were able to detect the presence of mercury and lead ions in aqueous solutions ...

  9. Removal of metal ions using dead-end filtration

    African Journals Online (AJOL)

    2005-07-03

    Jul 3, 2005 ... Surfactants due to their high selectivity properties have been used in enhancing membrane filtration for the removal of metal ions in aqueous solutions. Natural surfactants are preferred to synthetic surfactants because the synthetic surfactants have the disadvantage of introducing secondary pollutants into ...

  10. Equilibrium and kinetics studies of metal ion adsorption on dyed ...

    African Journals Online (AJOL)

    Batch equilibration studies were conducted to determine the nature of adsorption of Zn (II) and Cu (II) onto dyed coconut pollens. The nature of adsorption of metal ions was explained using the Langmuir equation. The calculated values of equilibrium parameter indicated favourable adsorption by the adsorbents. Also the ...

  11. Effect of metal ion doping on the photocatalytic activity of ...

    Indian Academy of Sciences (India)

    The activity can be enhanced by the increasing of concentration of the doped metal ions. TiAlPO-5 (4, 8, 12 atom % of Ti) showed the highest photocatalytic activity among all the compounds and its activity was compared to that of Degussa P25 (TiO2). The activity of photocatalysts was correlated with the diffuse reflectance ...

  12. Equilibrium and kinetics studies of metal ion adsorption on dyed ...

    African Journals Online (AJOL)

    GREGO

    2007-04-02

    Apr 2, 2007 ... Batch equilibration studies were conducted to determine the nature of adsorption of Zn (II) and Cu (II) onto dyed coconut pollens. The nature of adsorption of metal ions was explained using the Langmuir equation. The calculated values of equilibrium parameter indicated favourable adsorption by the.

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

    Science.gov (United States)

    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.

  14. Do soft drinks affect metal ions release from orthodontic appliances?

    Science.gov (United States)

    Mikulewicz, Marcin; Wołowiec, Paulina; Loster, Bartłomiej W; Chojnacka, Katarzyna

    2015-01-01

    The effect of orange juice and Coca Cola(®) on the release of metal ions from fixed orthodontic appliances. A continuous flow system designed for in vitro testing of orthodontic appliances was used. Orange juice/Coca Cola(®) was flowing through the system alternately with artificial saliva for 5.5 and 18.5h, respectively. The collected samples underwent a multielemental ICP-OES analysis in order to determine the metal ions release pattern in time. The total mass of ions released from the appliance into orange juice and Coca Cola(®) (respectively) during the experiment was calculated (μg): Ni (15.33; 37.75), Cr (3.604; 1.052), Fe (48.42; ≥ 156.1), Cu (57.87, 32.91), Mn (9.164; 41.16), Mo (9.999; 30.12), and Cd (0.5967; 2.173). It was found that orange juice did not intensify the release of metal ions from orthodontic appliances, whereas Coca Cola(®) caused increased release of Ni ions. Copyright © 2015 Elsevier GmbH. All rights reserved.

  15. Human topoisomerase IIα uses a two-metal-ion mechanism for DNA cleavage

    Science.gov (United States)

    Deweese, Joseph E.; Burgin, Alex B.; Osheroff, Neil

    2008-01-01

    The DNA cleavage reaction of human topoisomerase IIα is critical to all of the physiological and pharmacological functions of the protein. While it has long been known that the type II enzyme requires a divalent metal ion in order to cleave DNA, the role of the cation in this process is not known. To resolve this fundamental issue, the present study utilized a series of divalent metal ions with varying thiophilicities in conjunction with DNA cleavage substrates that replaced the 3′-bridging oxygen of the scissile bond with a sulfur atom (i.e. 3′-bridging phosphorothiolates). Rates and levels of DNA scission were greatly enhanced when thiophilic metal ions were included in reactions that utilized sulfur-containing substrates. Based on these results and those of reactions that employed divalent cation mixtures, we propose that topoisomerase IIα mediates DNA cleavage via a two-metal-ion mechanism. In this model, one of the metal ions makes a critical interaction with the 3′-bridging atom of the scissile phosphate. This interaction greatly accelerates rates of enzyme-mediated DNA cleavage, and most likely is needed to stabilize the leaving 3′-oxygen. PMID:18653531

  16. Fluorescence array-based sensing of metal ions using conjugated polyelectrolytes.

    Science.gov (United States)

    Wu, Yi; Tan, Ying; Wu, Jiatao; Chen, Shangying; Chen, Yu Zong; Zhou, Xinwen; Jiang, Yuyang; Tan, Chunyan

    2015-04-01

    Array-based sensing offers several advantages for detecting a series of analytes with common structures or properties. In this study, four anionic conjugated polyelectrolytes (CPEs) with a common poly(p-pheynylene ethynylene) (PPE) backbone and varying pendant ionic side chains were designed. The conjugation length, repeat unit pattern, and ionic side chain composition were the main factors affecting the fluorescence patterns of CPE polymers in response to the addition of different metal ions. Eight metal ions, including Pb(2+), Hg(2+), Fe(3+), Cr(3+), Cu(2+), Mn(2+), Ni(2+), and Co(2+), categorized as water contaminants by the Environmental Protection Agency, were selected as analytes in this study. Fluorescence intensity response patterns of the four-PPE sensor array toward each of the metal ions were recorded, analyzed, and transformed into canonical scores using linear discrimination analysis (LDA), which permitted clear differentiation between metal ions using both two-dimensional and three-dimensional graphs. In particular, the array could readily differentiate between eight toxic metal ions in separate aqueous solutions at 100 nM. Our four-PPE sensor array also provides a practical application to quantify Pb(2+) and Hg(2+) concentrations in blind samples within a specific concentration range.

  17. Piezoelectric sensor for sensitive determination of metal ions based on the phosphate-modified dendrimer

    Science.gov (United States)

    Wang, S. H.; Shen, C. Y.; Lin, Y. M.; Du, J. C.

    2016-08-01

    Heavy metal ions arising from human activities are retained strongly in water; therefore public water supplies must be monitored regularly to ensure the timely detection of potential problems. A phosphate-modified dendrimer film was investigated on a quartz crystal microbalance (QCM) for sensing metal ions in water at room temperature in this study. The chemical structures and sensing properties were characterized by Fourier transform infrared spectroscopy and QCM measurement, respectively. This phosphate-modified dendrimer sensor can directly detect metal ions in aqueous solutions. This novel sensor was evaluated for its capacity to sense various metal ions. The sensor exhibited a higher sensitivity level and shorter response time to copper(II) ions than other sensors. The linear detection range of the prepared QCM based on the phosphate-modified dendrimer was 0.0001 ∼ 1 μM Cu(II) ions (R2 = 0.98). The detection properties, including sensitivity, response time, selectivity, reusability, maximum adsorption capacity, and adsorption equilibrium constants, were also investigated.

  18. Cementation of silver ions on metallic copper

    International Nuclear Information System (INIS)

    Jaskula, M.

    2009-01-01

    The silver cementation on metallic copper was investigated in the presence or absence of oxygen. The influence of sulphuric acid and copper sulphate concentration on the silver cement morphology was studied in details, and results were linked with the previously determined kinetics data of the process. The morpgology of silver depopsit was found to be independent of the prosence of oxygen in the system in as well as the sulphuric acide concentration. Contrary, the concentration of copper sulphate strongly influenced the morphology of silver deposite. Two-stage mechanism of cementation was proposed. (authors).

  19. [Applications of atomic emission spectrum from liquid electrode discharge to metal ion detection].

    Science.gov (United States)

    Mao, Xiu-Ling; Wu, Jian; Ying, Yi-Bin

    2010-02-01

    The fast and precise detection of metal ion is an important research project concerning studies in diverse academic fields and different kinds of detecting technologies. In the present paper, the authors review the research on atomic emission spectrum based on liquid electrode discharge and its applications in the detection of metal ion. In the first part of this paper the principles and characteristics of the methods based on electrochemistry and spectroscopy were introduced. The methods of ion-selective electrode (ISE), anodic stripping voltammetry, atomic emission spectrum and atomic absorption spectrum were included in this part and discussed comparatively. Then the principles and characteristics of liquid electrode spectra for metal ion detection were introduced. The mechanism of the plasma production and the characteristics of the plasma spectrum as well as its advantages compared with other methods were discussed. Secondly, the authors divided the discharge system into two types and named them single liquid-electrode discharge and double-liquid electrode respectively, according to the number of the liquid electrode and the configuration of the discharge system, and the development as well as the present research status of each type was illustrated. Then the characteristics and configurations of the discharge systems including ECGD, SCGD, LS-APGD and capillary discharge were discussed in detail as examples of the two types. By taking advantage of the technology of atomic emission spectrum based on liquid electrode discharge, the detecting limit of heavy metals such as copper, mercury and argent as well as active metal ions including sodium, potass and magnesium can achieve microg x L(-1). Finally, the advantages and problems of the liquid-electrode discharge applied in detection of metal ion were discussed. And the applications of the atomic emission spectrum based on liquid electrode discharge were prospected.

  20. Very broad beam metal ion source for large area ion implantation application

    International Nuclear Information System (INIS)

    Brown, I.; Anders, S.; Dickinson, M.R.; MacGill, R.A.; Yao, X.

    1993-01-01

    The authors have made and operated a very broad beam version of vacuum arc ion source and used it to carry out high energy metal ion implantation of a particularly large substrate. A multiple-cathode vacuum arc plasma source was coupled to a 50 cm diameter beam extractor (multiple aperture, accel-decel configuration) operated at a net extraction voltage of up to 50 kV. The metal ion species chosen were Ni and Ta. The mean ion charge state for Ni and Ta vacuum arc plasmas is 1.8 and 2.9, respectively, and so the mean ion energies were up to about 90 and 145 keV, respectively. The ion source was operated in a repetitively pulsed mode with pulse length 250 μs and repetition rate several pulses per second. The extracted beam had a gaussian profile with FWHM about 35 cm, giving a nominal beam area of about 1,000 cm 2 . The current of Ni or Ta metal ions in the beam was up to several amperes. The targets for the ion implantation were a number of 24-inch long, highly polished Cu rails from an electromagnetic rail gun. The rails were located about 80 cm away from the ion source extractor grids, and were moved across a diameter of the vessel in such a way as to maximize the uniformity of the implant along the rail. The saturation retained dose for Ta was limited to about 4 x 10 16 cm -2 because of the rather severe sputtering, in accordance with the theoretical expectations for these implantation conditions. Here they describe the ion source, the implantation procedure, and the kinds of implants that can be produced in this way

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

    Science.gov (United States)

    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.

  2. Nanostructured metal oxide-based materials as advanced anodes for lithium-ion batteries.

    Science.gov (United States)

    Wu, Hao Bin; Chen, Jun Song; Hng, Huey Hoon; Lou, Xiong Wen David

    2012-04-21

    The search for new electrode materials for lithium-ion batteries (LIBs) has been an important way to satisfy the ever-growing demands for better performance with higher energy/power densities, improved safety and longer cycle life. Nanostructured metal oxides exhibit good electrochemical properties, and they are regarded as promising anode materials for high-performance LIBs. In this feature article, we will focus on three different categories of metal oxides with distinct lithium storage mechanisms: tin dioxide (SnO(2)), which utilizes alloying/dealloying processes to reversibly store/release lithium ions during charge/discharge; titanium dioxide (TiO(2)), where lithium ions are inserted/deinserted into/out of the TiO(2) crystal framework; and transition metal oxides including iron oxide and cobalt oxide, which react with lithium ions via an unusual conversion reaction. For all three systems, we will emphasize that creating nanomaterials with unique structures could effectively improve the lithium storage properties of these metal oxides. We will also highlight that the lithium storage capability can be further enhanced through designing advanced nanocomposite materials containing metal oxides and other carbonaceous supports. By providing such a rather systematic survey, we aim to stress the importance of proper nanostructuring and advanced compositing that would result in improved physicochemical properties of metal oxides, thus making them promising negative electrodes for next-generation LIBs.

  3. Ion spectra of the metal vapor vacuum arc ion source with compound and alloy cathodes

    Science.gov (United States)

    Sasaki, Jun; Brown, Ian G.

    1990-01-01

    In metal vapor vacuum arc (MEVVA) ion sources, vacuum arc plasma with cathodes of single, pure elements has been utilized for the production of metal ions. In this study, we have investigated the charge state distributions of ions produced in vacuum arc plasmas in a MEVVA ion source for the case when the cathode is an alloy or a compound material. The ion charge state spectra were analyzed by means of a time-of-flight apparatus. We have compared the ion spectra for a cathode of an alloy or a compound material with its constituent elements: TiC/TiN/TiO2/Ti/C, SiC/Si/C, WC/W/C U/UN/(UN-ZrC)/Zr/C, and brass/Zn/Cu. We find that the MEVVA produces ions of all constituent elements in the compound and the alloy cathodes. The charge state distribution of each element differs, however, from the charge state distribution obtained in the vacuum arc with a cathode made of the pure, single constituent element. Fractional values of the total ion numbers of each constituent element in the extracted beam depart from the stoichiometry of the elements in the cathode material. In an operation with a TiC cathode, we irradiated a 304 stainless-steel plate with the extracted beam. Results from glow-discharge spectroscopy (GDS) of the surface show that both titanium and carbon are implanted in the substrate after the irradiation.

  4. Metal ion levels and lymphocyte counts

    DEFF Research Database (Denmark)

    Penny, Jeannette Ø; Varmarken, Jens-Erik; Ovesen, Ole

    2013-01-01

    . RESULTS: The T-lymphocyte counts for both implant types declined over the 2-year period. This decline was statistically significant for CD3(+)CD8(+) in the THA group, with a regression coefficient of -0.04 × 10(9)cells/year (95% CI: -0.08 to -0.01). Regression analysis indicated a depressive effect...... of cobalt ions in particular on T-cells with 2-year whole-blood cobalt regression coefficients for CD3+ of -0.10 (95% CI: -0.16 to -0.04) × 10(9) cells/parts per billion (ppb), for CD3+CD4+ of -0.06 (-0.09 to -0.03) × 10(9) cells/ppb, and for CD3(+)CD8(+) of -0.02 (-0.03 to -0.00) × 10(9) cells...

  5. COMPARATIVE STUDY ON METAL IONS ADSORPTION ON A LOW COST CARBONACEOUS ADSORBENT KINETIC EQUILIBRIUM AND MECHANISTIC STUDIES

    Directory of Open Access Journals (Sweden)

    S. Arivoli, M. Hema, C. Barathiraja

    2008-01-01

    Full Text Available A carbonaceous adsorbent prepared from an indigenous waste and treated by acid was tested for its efficiency in removing metal ions of Fe(II, Co(II and Ni(II. The process parameters studied included agitation time, initial metal ion concentration, carbon dosage, pH, other ions and temperature. The kinetics of adsorption followed first order reaction equation and the rate was mainly controlled by intraparticle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacity obtained from the Langmuir isotherm plots was found around 28mg/g for all selected metal ions at an initial pH of 6. The temperature variation study showed that the metal ions adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying pH of the metal ion solutions. The type I and II isotherms obtained, positive H0 values, pH dependent results and desorption of metal ions in mineral acid suggests that the adsorption of metal ions on this type of adsorbent involves both chemisorption and physical adsorption mechanisms.

  6. Outcome and serum ion determination up to 11 years after implantation of a cemented metal-on-metal hip prosthesis.

    Science.gov (United States)

    Lazennec, Jean-Yves; Boyer, Patrick; Poupon, Joel; Rousseau, Marc-Antoine; Roy, Carine; Ravaud, Philippe; Catonné, Yves

    2009-04-01

    Little is known about the long-term outcome of cemented metal-on-metal hip arthroplasties. We evaluated a consecutive series of metal-on-metal polyethylene-backed cemented hip arthroplasties implanted in patients under 60 years of age. 109 patients (134 joint replacements) were followed prospectively for mean 9 (7-11) years. The evaluation included clinical score, radiographic assessment, and blood sampling for ion level determination. At the final review, 12 hips had been revised, mainly because of aseptic loosening of the socket. Using revision for aseptic loosening as the endpoint, the survival rate at 9 years was 91% for the cup and 99% for the stem. In addition, 35 hips showed radiolucent lines at the bone-cement interface of the acetabulum and some were associated with osteolysis. The median serum cobalt and chromium levels were relatively constant over time, and were much higher than the detection level throughout the study period. The cobalt level was 1.5 microg/L 1 year after implantation, and 1.44 microg/L 9 years after implantation. Revisions for aseptic loosening and radiographic findings in the sockets led us to halt metal-on-metal-backed polyethylene cemented hip arthroplasty procedures. If the rigidity of the cemented socket is a reason for loosening, excessive release of metal ions and particles may be involved. Further investigations are required to confirm this hypothesis and to determine whether subluxation, microseparation, and hypersensitivity also play a role.

  7. Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations

    OpenAIRE

    Dahlstrand, Henrik; Stark, André; Wick, Marius C; Anissian, Lucas; Hailer, Nils P; Weiss, Rüdiger J

    2017-01-01

    Background and purpose Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods 85 patients w...

  8. Interaction of Metal Ions with Biomolecular Ligands: How Accurate Are Calculated Free Energies Associated with Metal Ion Complexation?

    Czech Academy of Sciences Publication Activity Database

    Gutten, Ondrej; Beššeová, Ivana; Rulíšek, Lubomír

    2011-01-01

    Roč. 115, č. 41 (2011), s. 11394-11402 ISSN 1089-5639 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z40550506 Keywords : metal-ion selectivity * theoretical calculations * stability constants Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  9. Kinetic study of heavy metal ions removal by ion exchange in batch conical air spouted bed

    Directory of Open Access Journals (Sweden)

    T.M. Zewail

    2015-03-01

    Full Text Available Spouted bed contactor is a hybrid of fixed and fluidized bed contactors, which retains the advantages of each with good hydrodynamic conditions. The aim of the present study is to investigate the performance of a batch conical air spouted vessel for heavy metal removal by strong cation exchange resins (AMBERJET 1200 Na. The effect of various parameters such as type of heavy metal ions (Ni+2 and Pb+2, contact time, superficial air velocity and initial heavy metal ion concentration on % heavy metal ion removal has been investigated. It has been found that under optimum conditions 98% and 99% removal of Ni+2 and Pb+2 were achieved respectively. Several kinetic models were used to test the experimental data and to examine the controlling mechanism of the sorption process. The present results of Ni+2 and Pb+2 well fit pseudo second order kinetic model with a high correlation coefficient. Both film diffusion and intra-particle diffusion contribute to the ion exchange process. The present study revealed that spouted bed vessel may provide an effective alternative for conducting ion exchange reactions.

  10. Ion conducting polymers and polymer blends for alkali metal ion batteries

    Science.gov (United States)

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Vitale, Alessandra

    2017-08-29

    Electrolyte compositions for batteries such as lithium ion and lithium air batteries are described. In some embodiments the compositions are liquid compositions comprising (a) a homogeneous solvent system, said solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO); and (b) an alkali metal salt dissolved in said solvent system. In other embodiments the compositions are solid electrolyte compositions comprising: (a) a solid polymer, said polymer comprising a crosslinked product of a crosslinkable perfluropolyether (PFPE) and a crosslinkable polyethylene oxide (PEO); and (b) an alkali metal ion salt dissolved in said polymer. Batteries containing such compositions as electrolytes are also described.

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

    Science.gov (United States)

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

    2016-05-01

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

  12. Adsorptive Removal of Metal Ions from Water using Functionalized Biomaterials.

    Science.gov (United States)

    Deshpande, Kanchanmala

    2017-01-01

    Synthesis and modification of cost-effective sorbents for removing heavy metals from water resources is an area of significance. It had been reported that materials with biological origins, such as agricultural and animal waste, are excellent alternatives to conventional adsorbents due to their higher affinity, capacity and selectivity towards metal ions. These properties of biomaterials help to reduce or detoxify metal ions concentration in contaminated water to acceptable regulatory standards. Synthesis of novel, efficient, cost effective, eco-friendly biomaterials for heavy metal adsorption from water is still an area of challenge. In this comprehensive review, acompilation of patents as well as published articles is carried out to outline the properties of different biomaterials based on their precursors along withdetailed description of biomaterial morphology and various surface modification approaches. A detailed study of the performance of adsorbents and the role of physical and chemical modification in terms of enhancing their potential for metal adsorption from water is compiled here. The factors affecting adsorption behavior i.e., capacity and affinity of e biomaterials is also compiled. This paper presents a concise review of reported studies on the synthesis and modification of biomaterials, their use for heavy metal removal from waters and future prospects of this technology. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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.

  14. Ions, isotopes, and metal cyanides: Observational and laboratory studies

    Science.gov (United States)

    Savage, Chandra Shannon

    2004-11-01

    Chemistry in the interstellar medium is very different from the processes which take place in terrestrial settings. Environments such as circumstellar envelopes, molecular clouds, and comets contain diverse and complex chemical networks. The low temperatures (10 50 K) and densities (1 10 6 cm-3) allow normally unstable molecules to exist in significant quantities. At these temperatures, the rotational energy levels of molecules are populated, and thus these species can be detected by millimeter-wave radio astronomy. The detection and quantification of interstellar molecules, including metal cyanides and molecular ions, is the basis of this dissertation work. While conducting observations of CN and 13CN to determine the 12C/13C ratio throughout the Galaxy, it was found that the ratios in photon- dominated regions (PDRs) were much higher than those in nearby molecular clouds. This can be explained by isotope-selective photodissociation, in which the 12CN molecules are self-shielded. However, the chemistry in these regions is poorly understood, and other processes may be occurring. In order to understand one of the chemical networks present in PDRs, observations of HCO+, HOC +, and CO+ were made toward several of these sources. Previous studies indicated that the HCO+/HOC+ ratio was much lower in PDRs, due to the presence of CO+. The new observations indicate that there is a strong correlation between CO + and HOC+ abundances, which suggests that other molecular ions which have not been detected in molecular clouds may be present in PDRs. There is a significant obstacle to the detection of new interstellar molecular ions, however. The laboratory spectra are virtually unknown for many of these species, due to their inherent instability. Thus, techniques which can selectively detect ionic spectra must be utilized. One such method is velocity modulation, which incorporates an AC electrical discharge to produce and detect ions. Previously, velocity modulation spectroscopy

  15. A Selective Bioreduction of Toxic Heavy Metal Ions from Aquatic Environment by Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    A. M. Rahatgaonkar

    2008-01-01

    Full Text Available The need to remove or recover metal ions from industrial wastewater has been established in financial as well as environmental terms. This need has been proved financially in terms of cost saving through metal reuse or sale and environmentally as heavy metal toxicity can affect organisms throughout the food chain, including humans. Bioremediation of heavy metal pollution remains a major challenge in environmental biotechnology. Current removal strategies are mainly based on bioreduction of Co++, Ni++, Cu++ and Cd++ to their metallic forms by Saccharomyces cerevisiae in buffered aqueous solution. The rate of biotransformation was significantly influenced by pH of aqueous solution, concentration of biomass and hardness of water. All reaction conditions were optimized and maximum reduction of Co++, Cd++, Ni++ and Cu++ were observed as 80%, 63%, 50%, and 44% respectively. Unreacted Co++, Cd++, Ni++metal ions were extracted by 8-hydroxyquinoline and Cu++ by diethylthio carbamate in CHCl3 at different pH. Furthermore, the concentrations of unreacted metal ions were established spectrophotometrically.

  16. Ion beam mixing isotopic metal bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fell, C.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    In order to obtain an insight into the mechanisms of ion-solid interactions, bilayer targets can be prepared from two different isotopes. A mixing study SIMS is to be carried out using specially grown monocrystalline bilayers of {sup 58}Ni / {sup 60}Ni. An important aspect of the work is the preparation of high quality single-crystal thin films. The Ni layers will be grown on the (110) surface of pure Ni and verified for crystallinity using Reflection High-Energy Electron Diffraction and Rutherford Backscattering channelling analysis. The Pd bilayers will be grown on a Pd (100) surface. RHEED will be used to confirm the two-dimensional crystallinity of the surface before and after deposition of each layer, and channelling used to confirm bulk film crystallinity. Single crystal substrates are currently being prepared. Analysis of the Ni (110) surface using RHEED at 9 kV shows a streak spacing which corresponds to a lattice spacing of 2.47 {+-} 0.09 Angstroms. 9 refs., 1 fig.

  17. Polymer filtration systems for dilute metal ion recovery

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Electron emission during multicharged ion-metal surface interactions

    International Nuclear Information System (INIS)

    Zeijlmans van Emmichoven, P.A.; Havener, C.C.; Hughes, I.G.; Overbury, S.H.; Robinson, M.T.; Zehner, D.M.; Meyer, F.W.

    1992-01-01

    The electron emission during multicharged ion-metal surface interactions will be discussed. The interactions lead to the emission of a significant number of electrons. Most of these electrons have energies below 30 eV. For incident ions with innershell vacancies the emission of Auger electrons that fill these vacancies has been found to occur mainly below the surface. We will present recently measured electron energy distributions which will be used to discuss the mechanisms that lead to the emission of Auger and of low-energy electrons

  19. Wear properties of metal ion implanted 4140 steel

    International Nuclear Information System (INIS)

    Evans, P.J.; Paoloni, F.J.

    1994-01-01

    AISI type 4140 (high tensile) steel has been implanted with tungsten and titanium using a metal vapour vacuum arc ion source. Doses in the range (1-5)x10 16 ionscm -2 were implanted to a depth of approximately 30nm. The relative wear resistance between non-implanted and implanted specimens has been estimated using pin-on-disc and abrasive wear tests. Implantation of titanium decreased the area of wear tracks by a factor of 5 over unimplanted steel. In some cases the steel was also hardened by a liquid carburization treatment before implantation. Abrasion tests revealed a further improvement in wear resistance on this material following ion irradiation. ((orig.))

  20. Development of carbon and metallic nano particle composite materials for the determination of uranium and other heavy metal ions

    International Nuclear Information System (INIS)

    Sahoo, S.; Dey, M.K.; Satpati, A.K.; Reddy, A.V.R.

    2014-01-01

    Carbon and metallic nano particle based composite materials were developed and characterised for the determination of heavy metal ions and uranium in trace concentration levels. Composite material were electrodeposited on the substrate electrode and applied for the electrochemical determination of metal ions. Electrodeposition parameters to synthesise the composite material and the analytical parameters for determination were optimised. (author)

  1. Electroplating Ni-63 metal ions in chloride bath on the Cu-plate

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Kwon Mo; Uhm, Young Rang; Son, Kwang Jae; Park, Keun Yung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Ni-63 plating is similar to other electroplating processes that employ soluble metal anodes. The nickel plating solution described by Watts in 1916 eventually replaced all other strategies in use up to that time. Charged Ni ions are formed by sulfate, sulfamate, chloride, and a Watts bath. However, charged Ni-63 ions are formed by dissolving metal Ni-63. Specifically, it requires the passage of direct current (DC) between two electrodes that are immersed in a conductive, aqueous solution of nickel salts. The flow of a DC causes one of the electrodes (the anode) to dissolve and the other electrode (the cathode) to become covered with nickel. The nickel in the solution is present in the form of divalent positively charged ions (Ni{sup 2+}). When the current flows, the positive ions react with two electrons (2e{sup -}) and are converted into metallic nickel (Ni{sup 0}) at the cathode surface. In the present study, we optimize and established process for the electroplating Ni-63 on Cu-plate. Nanocrystalline nickel (Ni) coatings were synthesized by DC electro deposition at a current density of 15 mA/cm{sup 2}. The bath was primarily composed of 0.2 M Ni ions, prepared by dissolving Ni-63 metal particles in HCl. The prototype for electroplating radioactive Ni-63 has been established. The electroplating was carried out by two-step processes such as preparation of ionic solution including Ni-63, and coating processes on the substrate.

  2. Metal ion toxins and brain aquaporin-4 expression: an overview

    Directory of Open Access Journals (Sweden)

    Adriana eXimenes-Da-Silva

    2016-06-01

    Full Text Available 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.

  3. Kinetic modeling of metal ion transport for desorption of Pb(II) ion ...

    African Journals Online (AJOL)

    The kinetics of desorption of lead (II) ion from metal loaded adsorbent of mercaptoacetic acid modified and unmodified oil palm (Elaeis guineensis) fruit fiber was studied using different solutions, at different contact times. At the end of 25 minutes, 79.19%, 75.99%, 57.14%, 50.56% and 32.72% of Pb2+ were desorbed using ...

  4. The essential roles of metal ions in insect homeostasis and physiology.

    Science.gov (United States)

    Dow, Julian At

    2017-10-01

    Metal ions play distinct roles in living organisms, including insects. Some, like sodium and potassium, are central players in osmoregulation and 'blood and guts' transport physiology, and have been implicated in cold adaptation. Calcium is a key player as a second messenger, and as a structural element. Other metals, particularly those with multiple redox states, can be cofactors in many metalloenzymes, but can contribute to toxic oxidative stress on the organism in excess. This short review selects some examples where classical knowledge has been supplemented with recent advances, in order to emphasize the importance of metals as essential nutrients for insect survival. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Clinical Results and Serum Metal Ion Concentrations following Ceramic-on-Metal Total Hip Arthroplasty at a Mean Follow-Up of 60 Months

    Science.gov (United States)

    Maurer-Ertl, W.; Pranckh-Matzke, D.; Bratschitsch, G.; Maier, M.

    2017-01-01

    Background. Increased metal ion levels following total hip arthroplasty (THA) with metal-on-metal bearings are a highly debated topic. Local soft tissue reactions with chronic pain and systemic side effects such as neuropathy are described. The aim of the current study was to determine the serum metal ion concentrations of Cobalt (Co) and Chrome (Cr) after THA with a ceramic-on-metal (CoM) bearing. Patients and Methods. Between 2008 and 2010, 20 patients underwent THA using a CoM bearing. Clinical function was evaluated by standardized scores systems (Harris Hip Score and WOMAC Score) and radiological examination included X-rays. Patient's blood samples were obtained for metal ion analysis and correlation analysis was done between these results and implant position. Results. Overall, 13 patients with 14 CoM devices were available for the current series. The mean age at time of surgery was 61 years (range, 41 to 85). The postoperative follow-up ranged from 49 to 68 months (mean, 58). Metal ion determination showed mean concentrations of 3,1 µg/L (range, 0,3–15,2 µg/L) for Co and 1,6 µg/L (range, 0,1–5,5 µg/L) for Cr, respectively. A correlation between cup anteversion and Co and Cr concentrations was shown. Conclusion. The current series showed increments for Co and Cr following CoM THA. However, these levels are lower compared to metal ion concentrations in patients with metal-on-metal bearings and the international accepted threshold for revision of MoM devices. We recommend routine follow-up including at least one obligatory evaluation of serum metal ion concentrations and an MRI once to exclude local soft tissue reactions. PMID:28373980

  6. General Synthesis of Transition-Metal Oxide Hollow Nanospheres/Nitrogen-Doped Graphene Hybrids by Metal-Ammine Complex Chemistry for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Chen, Jiayuan; Wu, Xiaofeng; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Peng, Shengpan; Tan, Qiangqiang; Chen, Yunfa

    2018-02-09

    We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, for synthesizing hollow transition-metal oxides (Co 3 O 4 , NiO, CuO-Cu 2 O, and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high-performance lithium-ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition-metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co 2+ , Ni 2+ , Cu 2+ , or Zn 2+ )-ammine complex ions. Moreover, the hollowing process is well correlated with the complexing capacity between metal ions and NH 3 molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ions, and no hollow structures formed for weak and/or noncomplex Mn 2+ and Fe 3+ ions. Simultaneously, this novel strategy can also achieve the direct doping of nitrogen atoms into the graphene framework. The electrochemical performance of two typical hollow Co 3 O 4 or NiO/nitrogen-doped graphene hybrids was evaluated by their use as anodic materials. It was demonstrated that these unique nanostructured hybrids, in contrast with the bare counterparts, solid transition-metal oxides/nitrogen-doped graphene hybrids, perform with significantly improved specific capacity, superior rate capability, and excellent capacity retention. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Metals on the move: zinc ions in cellular regulation and in the coordination dynamics of zinc proteins.

    Science.gov (United States)

    Maret, Wolfgang

    2011-06-01

    Homeostatic control maintains essential transition metal ions at characteristic cellular concentrations to support their physiological functions and to avoid adverse effects. Zinc is especially widely used as a catalytic or structural cofactor in about 3000 human zinc proteins. In addition, the homeostatic control of zinc in eukaryotic cells permits functions of zinc(II) ions in regulation and in paracrine and intracrine signaling. Zinc ions are released from proteins through ligand-centered reactions in zinc/thiolate coordination environments, and from stores in cellular organelles, where zinc transporters participate in zinc loading and release. Muffling reactions allow zinc ions to serve as signaling ions (second messengers) in the cytosol that is buffered to picomolar zinc ion concentrations at steady-state. Muffling includes zinc ion binding to metallothioneins, cellular translocations of metallothioneins, delivery of zinc ions to transporter proteins, and zinc ion fluxes through cellular membranes with the result of removing the additional zinc ions from the cytosol and restoring the steady-state. Targets of regulatory zinc ions are proteins with sites for transient zinc binding, such as membrane receptors, enzymes, protein-protein interactions, and sensor proteins that control gene expression. The generation, transmission, targets, and termination of zinc ion signals involve proteins that use coordination dynamics in the inner and outer ligand spheres to control metal ion association and dissociation. These new findings establish critically important functions of zinc ions and zinc metalloproteins in cellular control.

  8. Multiply charged metal ions in high current pulsed vacuum arcs

    Science.gov (United States)

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

    2017-12-01

    We show that vacuum arc plasma discharges with a current of several kiloamperes and duration of a few microseconds can generate multiply charged metal ions with charge states greater than 10+. The physical mechanism behind this is discussed, suggesting an optimum arc current for higher charge states depending on the pulse duration and cathode material. Measurements of ion mass-to-charge ratio and images taken with nanosecond resolution suggest that, higher charge state ions are produced at characteristic distances of ˜10 mm from the cathode as the arc current peaks, and the process responsible for their generation is additional ionization as the discharge is pinched by its self-magnetic field. The maximum and mean ion charge states reveal a considerable increase for the all cathode materials studied: magnesium, aluminum, zirconium, tin, tantalum, gold, lead, and bismuth. For bismuth ions, the maximum charge state reaches a record-breaking value of 17+ and the mean of the charge state distribution is 12.6+. The results obtained are of interest for vacuum arc discharge physics and for ion beam technologies.

  9. Adsorption of heavy metal ions by activated charcoal

    International Nuclear Information System (INIS)

    Fujikawa, Mitsuo

    1978-01-01

    The adsorption effect was measured for several kinds of heavy metal ions, Pb 2+ , Cd 2+ , Cu 2+ and Zn 2+ by passing them through activated charcoal beds and changing the pH values of solutions. The test procedure is to keep the pH value of solution more than 10 at first, filter heavy metal hydroxide deposit, measure the remaining ion concentration in filtrate, and also test the influence of the addition of alkali to each kind of ions. The individual test procedure for each kind of ions is explained. As for the Cd ions, after the detailed experimental procedure is explained, the adsorption characteristic line is shown as the relation between the adsorption quantity and the equilibrium concentration of Cd 2+ . The similar test procedure and the adsorption characteristic lines are shown and evaluated about Pb 2+ , Cu 2+ and Zn 2+ . These lines are all linear, but have different adsorption quantity and inclination in relation to heavy metal ion concentration. Concerning the influence of pH to adsorption, the characteristics of pH increase are presented, when alkali is added by various quantities to Zn 2+ , Cu 2+ , Pb 2+ and Cd 2+ . The pH of Pb 2+ increased to about 10 by adding 0.4 cc alkali and saturates, but the pH of the other ions did not saturate by adding less than 1.5 cc alkali. When the water containing heavy metals are treated, Cd 2+ , Pb 2+ , Cu 2+ and Zn 2+ are removed almost satisfactorily by passing them through active charcoal filters and keeping pH at 10. The experimental concentrations are 0.05 ppm at pH 10 in Cd, 0.86 ppm at 10.3 in Pb, 0 ppm at pH 9.6 in Cu, 0.06 ppm at pH 8.8 and 12.4 ppm at pH 9.8 in Zn. (Nakai, Y.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Gas porosity in metals and alloys irradiated by helium ions

    International Nuclear Information System (INIS)

    Kalin, B.A.; Korshunov, S.N.; Chernov, I.I.

    1987-01-01

    Experimental studies of the development of gas porosity in metals and alloys during irradiation with helium ions up to high doses and during post-irradiation annealings, are reviewed. The main theoretical problems of the mechanisms of bubble formation and growth, the regularities and peculiarities of bubble development in a thin near-the surface layer during the introduction of helium with the energy of tens of kiloelectron volt, are considered

  12. Towards the role of metal ions in the structural variability of proteins: CdII speciation of a metal ion binding loop motif

    DEFF Research Database (Denmark)

    Jancsó, Attila; Szunyogh, Dániel; Gyurcsik, Béla

    2011-01-01

    A de novo designed dodecapeptide (HS), inspired by the metal binding loops of metal-responsive transcriptional activators, was synthesized. The aim was to create a model system for structurally promiscuous and intrinsically unstructured proteins, and explore the effect of metal ions on their stru...... the peptide is exchanging between a number of structures also in its metal ion bound state(s), as indicated by NMR and PAC data. © 2011 The Royal Society of Chemistry....

  13. In situ NMR measurement of macromolecule-bound metal ion concentrations.

    Science.gov (United States)

    Kozlyuk, Natalia; Sengupta, Suvrajit; Lupták, Andrej; Martin, Rachel W

    2016-04-01

    Many nucleic acids and proteins require divalent metal ions such as Mg(2+) and Ca(2+) for folding and function. The lipophilic alignment media frequently used as membrane mimetics also bind these divalent metals. Here we demonstrate the use of (31)P NMR spectrum of a metal ion chelator (deoxycytidine diphosphate) to measure the bound [Mg(2+)] and [Ca(2+)] in situ for several biological model systems at relatively high divalent ion concentrations (1-10 mM). This method represents a general approach to measuring divalent metal ion binding in NMR samples where the amount and type of metal ion added to the system is known.

  14. Spectrophotometric determination of some metal ions using hydrazones

    International Nuclear Information System (INIS)

    Mohammed, M. S.

    2000-05-01

    In this research many starting materials were prepared, like methyl salicylate and salicylic acid hydrazide from which different derivatives of hydrazones were synthesized by coupling with carbonyl compounds like benzil monoxime and benzil mono hydrazone which are prepared and others like salicylaldehyde and benzoin. The hydrazones that were synthesized are salicylaldehyde salicylic acid hydrazone, benzoin salicylic acid hydrazone, benzil mono hydrazone salicylic acid hydrazone and benzil monoxime salicylic acid hydrazone. These reagents were determined by different methods, IR spectrophotometric determination, the nitrogen content method and melting point determination. These hydrazones act as ligands for determination of some metal ions by making different coloured complexes that were prepared for eight hydrazones with eight metal ions U (VI), Fe (II), Fe (III), Co (II), V (II), Mo (VI), Ni (II) and Cu (II). These complexes were determined by ultraviolet and visible spectrophotometer (UV/VIS) to detect their absorbance and wavelengths (λ max). The two hydrazones salicylaldehyde salicylic acid-hydrazone and benzoin salicylic acid hydrazone, were selected for determination of five metal ions (Fe (II), Fe (III), U (VI), Ni (II) and Cu (II)), using two micelles sodium n-dodecyl sulphate and pyridinium hexa decyl bromide mono hydrate. Their absorbance and wavelengths were detected using UV/VIS spectrophotometer. (Author)

  15. Adhesive and abrasive wear mechanisms in ion implanted metals

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1985-01-01

    The distinction between adhesive and abrasive wear processes was introduced originally by Burwell during the nineteen-fifties, though some authors prefer to classify wear according to whether it is mild or severe. It is argued here that, on the basis of the performance of a variety of ion implanted metal surfaces, exposed to different modes of wear, the Burwell distinction is a valid one which, moreover, enables us to predict under which circumstances a given treatment will perform well. It is shown that, because wear rates under abrasive conditions are very sensitive to the ratio of the hardness of the surface to that of the abrasive particles, large increases in working life are attainable as a result of ion implantation. Under adhesive wear conditions, the wear rate appears to fall inversely as the hardness increases, and it is advantageous to implant species which will create and retain a hard surface oxide or other continuous film in order to reduce metal-metal contact. By the appropriate combination of physico-chemical changes in an implanted layer it has been possible to reduce wear rates by up to three orders of magnitude. Such rates compensate for the shallow depths achievable by ion implantation. (orig.)

  16. Spectrophotometric study of some metal ions using some Schiff's bases

    International Nuclear Information System (INIS)

    Elnager, Nawal Mohomed Ibrahim

    2000-05-01

    In this work two schiff bases namely N,N Bis(benzoyl acetone)-o-phenylene diamine (NNBBPD) and N,N Bis(benzoyl acetone)-isopropylene diamine (NNBBAID) were prepared by direct coupling of benzoyl acetone with o-phenylene and isopropylene diamine respectively. The two reagents were identified by IR spectra, thin layer chromatography (TLC) and determination of the percentage of nitrogen contents (N%). It is found that the two reagents form coloured chelates with Fe (II), Fe (III), Cu (II), U (VI), Ni (II) and Co (II). The two reagents were used for the determination of Fe (II), Fe (III) and U (VI). The formulate of these metal ion complexes were obtained using continuous variations, mole ratio and slope ratio methods. Effect of two micelles, namely sodium n-dodecyl sulphate (SDS) and hexadecyl pyridinum broinide monohydrate (HPB) on metal ion complexes were studied. It is found that both of them increase the solubility and the absorbances of the metal ion complexes with variable effects of the absorption maxima. Calibration curves for Fe (II), Fe (II) and U (VI) were obtained in optimum conditions of pH and micelles solutions. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Lentz, Nicholas B. [Iowa State Univ., Ames, IA (United States)

    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

  18. Metal negative ion production by a planar magnetron sputter type radio frequency ion source

    Science.gov (United States)

    Yoshioka, K.; Kanda, S.; Kasuya, T.; Wada, M.

    2017-08-01

    A planar magnetron sputter type ion source has been operated to investigate metal negative ion production. Radio frequency power at 13.56 MHz was directly supplied to the planar target made of 2 mm thick Cu disk to maintain plasma discharge and induce DC self-bias to the target for sputtering. Beam profile was obtained and the peak of negative ion beam profile was shifted to 6 mm as the beam traversed the 32 mT magnetic field in the region of the plasma grid. Extraction of Cu- beam was performed and the Cu- beam current was found consisted of two components: Cu-(surface) and Cu-(volume). Negative ion spectra were observed to measure the ratio of the surface component to the volume component. The surface component of Cu- occupied 67% of the total beam at the maximum, while it decreased the fraction down to about 50% as the source pressure was increased.

  19. Properties of Transition Metal Atoms and Ions

    Energy Technology Data Exchange (ETDEWEB)

    Donald, Beck, R.

    2008-03-18

    Accomplishments of this project include: (1) improvement of the accuracy and efficiency of the RCI methodology to permit it to tackle almost all TM properties, and making good progress in extending these gains to the RE. Our improvements have stimulated improvements in the GRASP package, done by Froese Fischer. RCI efficiency gains are estimated to be {approx} 200x since the start of the project - about 10x from hardware improvements (originally DOE funded) and about 20x from software improvements. The net result is that currently the longest runs don't exceed 1 day. (2) identification and removal of systematic errors in several TM properties. To some extent, the PI became a 'court of last resort' for experimenters who wondered why certain theoretical-experimental discrepancies existed. Auxiliary analysis codes were written and successfully used to improve the systematic understanding of correlation effects in TM and RE. This improved efficiency and a priori understanding of what new projects might involve. [Unsurprisingly, there are several cases which the PI was unable to resolve. Work on these is unpublished]. (3) education and training of graduate students and postdocs.

  20. Structures and physical properties of gaseous metal cationized biological ions.

    Science.gov (United States)

    Burt, Michael B; Fridgen, Travis D

    2012-01-01

    Metal chelation can alter the activity of free biomolecules by modifying their structures or stabilizing higher energy tautomers. In recent years, mass spectrometric techniques have been used to investigate the effects of metal complexation with proteins, nucleobases and nucleotides, where small conformational changes can have significant physiological consequences. In particular, infrared multiple photon dissociation spectroscopy has emerged as an important tool for determining the structure and reactivity of gas-phase ions. Unlike other mass spectrometric approaches, this method is able to directly resolve structural isomers using characteristic vibrational signatures. Other activation and dissociation methods, such as blackbody infrared radiative dissociation or collision-induced dissociation can also reveal information about the thermochemistry and dissociative pathways of these biological ions. This information can then be used to provide information about the structures of the ionic complexes under study. In this article, we review the use of gas-phase techniques in characterizing metal-bound biomolecules. Particular attention will be given to our own contributions, which detail the ability of metal cations to disrupt nucleobase pairs, direct the self-assembly of nucleobase clusters and stabilize non-canonical isomers of amino acids.

  1. Removal Process of Heavy Metal Ions from Squid Gut Wastes with Dilute Suluric Acid Leaching and Electrowinning Methods

    OpenAIRE

    嶋影, 和宜; 平井, 伸治; 戸田, 茂雄; 山本, 浩

    2003-01-01

    In order to remove heavy metal ions contained in organic squid gut waste, a novel process has been developed with both dilute suluric acid leaching and electrowinning methods. This process was consisted of three procedures, which are the elimination of greasy component in squid gut wastes, the dissolution of heavy metal ions and the electro-deposition of heavy metal ions. Heavy metal ions contained in organic squid gut wastes are zinc, cadmium and copper ions. Heavy metal ions are leached eas...

  2. Extraction of metal ions by neutral β-diphosphoramides

    International Nuclear Information System (INIS)

    Madic, C.

    1990-01-01

    The extracting ability of β-diphosphoramides of the type R-N[P(O)(NMe 2 ) 2 ] 2 with R=-CH 3 (NIPA), -C 12 H 25 (ODIPA), or -C 16 H 33 (OHDIPA) for metal ions such as lanthanides, uranyl, and the transuranium elements Am(III) and Pu(IV) has been studied. Extraction yields depend on the nature of the ligand, the organic diluent (nitromethane, kerosene, tert-butylbenzene), the concentration of nitric acid in the aqueous phase, and the ligand-to-metal ratio, Q. The results show that the bidentate phosphoramides are very efficient extractants for all of the metals studied, even at low ratios Q. The presence of nitric acid generally enhances the extraction yields. On the other hand, selectivity is rather poor with these ligands. A particular effort has been made to determine the nature of extracted species by NMR spectroscopy

  3. Sorption of Heavy Metal Ions from Mine Wastewater by Activated ...

    African Journals Online (AJOL)

    Michael

    2016-12-02

    Dec 2, 2016 ... 1 Introduction. Various operations such as mineral processing tailings disposal, illegal mining, domestic waste disposal and many others result in the release of heavy metals into water bodies. The presence of these metals including Cadmium (Cd), Arsenic. (As), Chromium (Cr), Thallium (Tl), and Lead.

  4. Short-Term Metal Ion Trends Following Removal of Recalled Modular Neck Femoral Stems.

    Science.gov (United States)

    Barlow, Brian T; Assini, Joseph; Boles, John; Lee, Yuo-Yu; Westrich, Geoffrey H

    2015-07-01

    Elevated serum metal ions have been well documented with the Rejuvenate modular neck femoral stem (Stryker, Mahwah, NJ); however, the rate at which ion levels decline following revision is less clear. This study included fifty-nine consecutive revisions of Rejuvenate stems for symptomatic ALTR. Blood tests prior to revision and postoperatively at 6weeks, 3months, 6months, and 1year measured serum cobalt and chromium concentrations, ESR, and CRP. At six weeks following revision of a unilateral Rejuvenate, cobalt and chromium levels dropped from preoperative levels by 67% and 42%, respectively. At three months, cobalt levels declined to 19% of preoperative values, but chromium levels remained stable. With this information, surgeons can set realistic expectations for serum metal ion levels following Rejuvenate stem revision. Published by Elsevier Inc.

  5. Water-soluble metal-binding polymers with ultrafiltration: A technology for the removal, concentration, and recovery of metal ions from aqueous streams

    International Nuclear Information System (INIS)

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

    1997-01-01

    The use of water-soluble metal-binding polymers coupled with ultrafiltration (UF) is a technology under development to selectively concentrate and recover valuable or regulated metal-ions from dilute process or waste waters. The polymers have a sufficiently large molecular size that they can be separated and concentrated using commercially available UF technology. The polymers can then be reused by changing the solution conditions to release the metal-ions, which are recovered in a concentrated form for recycle or disposal. Pilot-scale demonstrations have been completed for a variety of waste streams containing low concentrations of metal ions including electroplating wastes (zinc and nickel) and nuclear waste streams (plutonium and americium). Many other potential commercial applications exist including remediation of contaminated solids. An overview of both the pilot-scale demonstrated applications and small scale testing of this technology are presented

  6. Water-soluble metal-binding polymers with ultrafiltration: A technology for the removal, concentration, and recovery of metal ions from aqueous streams

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

    The use of water-soluble metal-binding polymers coupled with ultrafiltration (UF) is a technology under development to selectively concentrate and recover valuable or regulated metal-ions from dilute process or waste waters. The polymers have a sufficiently large molecular size that they can be separated and concentrated using commercially available UF technology. The polymers can then be reused by changing the solution conditions to release the metal-ions, which are recovered in a concentrated form for recycle or disposal. Pilot-scale demonstrations have been completed for a variety of waste streams containing low concentrations of metal ions including electroplating wastes (zinc and nickel) and nuclear waste streams (plutonium and americium). Many other potential commercial applications exist including remediation of contaminated solids. An overview of both the pilot-scale demonstrated applications and small scale testing of this technology are presented.

  7. Using Metal Complex Ion-Molecule Reactions in a Miniature Rectilinear Ion Trap Mass Spectrometer to Detect Chemical Warfare Agents

    Science.gov (United States)

    Graichen, Adam M.; Vachet, Richard W.

    2013-06-01

    The gas-phase reactions of a series of coordinatively unsaturated [Ni(L)n]y+ complexes, where L is a nitrogen-containing ligand, with chemical warfare agent (CWA) simulants in a miniature rectilinear ion trap mass spectrometer were investigated as part of a new approach to detect CWAs. Results show that upon entering the vacuum system via a poly(dimethylsiloxane) (PDMS) membrane introduction, low concentrations of several CWA simulants, including dipropyl sulfide (simulant for mustard gas), acetonitrile (simulant for the nerve agent tabun), and diethyl phosphite (simulant for nerve agents sarin, soman, tabun, and VX), can react with metal complex ions generated by electrospray ionization (ESI), thereby providing a sensitive means of detecting these compounds. The [Ni(L)n]2+ complexes are found to be particularly reactive with the simulants of mustard gas and tabun, allowing their detection at low parts-per-billion (ppb) levels. These detection limits are well below reported exposure limits for these CWAs, which indicates the applicability of this new approach, and are about two orders of magnitude lower than electron ionization detection limits on the same mass spectrometer. The use of coordinatively unsaturated metal complexes as reagent ions offers the possibility of further tuning the ion-molecule chemistry so that desired compounds can be detected selectively or at even lower concentrations.

  8. Metal ion-mediated agonism and agonist enhancement in melanocortin MC1 and MC4 receptors

    DEFF Research Database (Denmark)

    Holst, Birgitte; Elling, Christian E; Schwartz, Thue W

    2002-01-01

    all MC receptors, are parts of the site. It is concluded that the function of the MC1 and MC4 receptors can be positively modulated by metal ions acting both as partial agonists and as potentiators for other agonists, including the endogenous peptide ligand alpha-MSH at Zn(II) concentrations......An endogenous metal-ion site in the melanocortin MC1 and MC4 receptors was characterized mainly in transiently transfected COS-7 cells. ZnCl(2) alone stimulated signaling through the Gs pathway with a potency of 11 and 13 microm and an efficacy of 50 and 20% of that of alpha...... of the metal ion appeared to be additive, because the maximal cAMP response for alpha-MSH in the presence of Zn(II) was 60% above the maximal response for the peptide alone. The affinity of Zn(II) could be increased through binding of the metal ion in complex with small hydrophobic chelators. The binding...

  9. Selective chelation-supercritical fluid extraction of metal ions from waste materials

    International Nuclear Information System (INIS)

    Wai, C.N.; Laintz, K.E.; Yonker, C.R.

    1993-01-01

    The removal of toxic organics, metals, and radioisotopes from solids or liquids is a major concern in the treatment of industrial and nuclear wastes. For this reason, developing methods for selective separation of toxic metals and radioactive materials from solutions of complex matrix is an important problem in environmental research. Recent developments indicate supercritical fluids are good solvents for organic compounds. Many gases become supercritical fluids under moderate temperatures and pressures. For example, the critical temperature and pressure of carbon dioxide are 31 degrees C and 73 atm, respectively. The high diffusivity, low viscosity, and T-P dependence of solvent strength are some attractive properties of supercritical fluid extraction (SFE). Since CO 2 offers the additional benefits of stability and non-toxicity, the SFE technique avoids generation of organic liquid waste and exposure of personnel to toxic solvents. While direct extraction of metal ions by supercritical fluids is highly inefficient, these ions when complexed with organic ligands become quite soluble in supercritical fluids. Specific ligands can be used to achieve selective extraction of metal ions in this process. After SFE, the fluid phase can be depressurized for precipitation of the metal chelates and recycled. The ligand can also be regenerated for repeated use. The success of this selective chelation-supercritical fluid extraction (SC-SFE) process depends on a number of factors including the efficiencies of the selective chelating agents, solubilities of metal chelates in supercritical fluids, rate of extraction, ease of regeneration of the ligands, etc. In this report, the authors present recent results on the studies of the solubilities of metal chelates in supercritical CO 2 , experimental ions from aqueous solution, and the development of selective chelating agents (ionizable crown ethers) for the extraction of lanthanides and actinides

  10. Environmental remediation of heavy metal ions from aqueous solution through hydrogel adsorption: a critical review.

    Science.gov (United States)

    Muya, Francis Ntumba; Sunday, Christopher Edoze; Baker, Priscilla; Iwuoha, Emmanuel

    2016-01-01

    Heavy metal ions such as Cd(2+), Pb(2+), Cu(2+), Mg(2+), and Hg(2+) from industrial waste water constitute a major cause of pollution for ground water sources. These ions are toxic to man and aquatic life as well, and should be removed from wastewater before disposal. Various treatment technologies have been reported to remediate the potential toxic elements from aqueous media, such as adsorption, precipitation and coagulation. Most of these technologies are associated with some shortcomings, and challenges in terms of applicability, effectiveness and cost. However, adsorption techniques have the capability of effectively removing heavy metals at very low concentration (1-100 mg/L). Various adsorbents have been reported in the literature for this purpose, including, to a lesser extent, the use of hydrogel adsorbents for heavy metal removal in aqueous phase. Here, we provide an in-depth perspective on the design, application and efficiency of hydrogel systems as adsorbents.

  11. Heavy metal ions adsorption from mine waters by sawdust

    Directory of Open Access Journals (Sweden)

    G. Bogdanović

    2009-10-01

    Full Text Available In this work the results on the batch and column adsorption of copper and some associated ions by employing linden and poplar sawdust as a low-cost adsorbent are presented. The mine water from a local abandoned copper mine, as well as synthetic solutions of those ions which are the main constituents of the mine water were both used as a model-system in this study. The adsorption ability of the chosen sawdust to adsorb heavy metal ions is considered as a function of the initial pH of the solution and kind of metal ions. At lower pH of solutions the adsorption percentage (AD % decreases leading to a zero AD % at pH < 1.1. Maximum AD % is achieved at 3.5 < pH < 5. It was found that poplar and linden sawdust have both almost equal adsorption capacities against copper ions. The highest AD % ( ≈80% was achieved for Cu2+, while for Fe2+ it was slightly above 10%. The other considered ions (Zn2+ and Mn2+ were within this interval. The results obtained in the batch mode were verified through the column test by using the real mine water originating from an acid mine drainage (AMD of the copper mine „Cerovo“, RTB Bor. The breakthrough curves are presented as a function of the aqueous phase volume passed through the column allowing having an insight into the column adsorption features. Breakthrough points were determined for copper, manganese and zinc ions. A very high adsorption degree – higher than 99% was achieved in these experiments for all mentioned ions. After completing the adsorption, instead of desorption, the loaded sawdust was drained, dried and burned; the copper bearing ash was then leached with a controlled volume of sulphuric acid solution to concentrate copper therein. The obtained leach solution had the concentration of copper higher than 15 g dm-3 and the amount of H2SO4 high enough to serve as a supporting electrolyte suitable to be treated by the electrowinning for recovery of copper. The technology process based on the column

  12. A simple alkali-metal and noble gas ion source for SIMS equipments with mass separation of the primary ions

    International Nuclear Information System (INIS)

    Duesterhoeft, H.; Pippig, R.

    1986-01-01

    An alkali-metal ion source working without a store of alkali-metals is described. The alkali-metal ions are produced by evaporation of alkali salts and ionization in a low-voltage arc discharge stabilized with a noble gas plasma or in the case of small alkali-metal ion currents on the base of the well known thermic ionization at a hot tungsten wire. The source is very simple in construction and produces a stable ion current of 0.3 μA for more than 100 h. It is possible to change the ion species in a short time. This source is applicable to all SIMS equipments using mass separation for primary ions. (author)

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

    Science.gov (United States)

    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.

  14. Method for intercalating alkali metal ions into carbon electrodes

    Science.gov (United States)

    Doeff, Marca M.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard

    1995-01-01

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

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

    Science.gov (United States)

    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.

  16. Hydration to the poly(oxyethylene) derivative complexes of alkali metal ions and barium ion in 1,2-dichloroethane

    International Nuclear Information System (INIS)

    Kikuchi, Yoichi; Kubota, Mitsuru; Suzuki, Toshio; Sawada, Kiyoshi.

    1994-01-01

    A series of poly(oxyethylene) derivatives (POE compound) complexes of alkali metal and barium ions were extracted into 1,2-dichloroethane (1,2-DCE) by forming ion-pairs with picrate ion. Water molecules were coextracted into 1,2-DCE with the ion-pairs. The mean number of water molecules bound to the POE compound, X H2O,S , and its complex, X H2O,comp , in water saturated with 1,2-DCE was determined by means of aquametry. The X H2O,S value increases with the increase in the number of the oxyethylene units (EO unit) of the POE compound. The X H2O,comp value decreases in the order Li + >Na + >K + ≅Rb + ≅Cs + in any POE compound systems, and increases with the number of EO units of the POE compounds for a given metal ion. These results are interpreted by the hypothesis that the water molecules bound to the complex are those hydrated to the central metal ion, and the hydrated metal ion is surrounded by the EO chain with a helical conformation in the complex. The large number of water molecules are coordinating to the lithium ion complexes and bring about a serious distortion in the helical structure of the complexes. Because of the ion-pair formation with two picrate ions, the X H2O,comp values of barium ion complexes are smaller than those of potassium ion complexes. (author)

  17. Hydration number of alkali metal ions determined by insertion in a conducting polymer

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2008-01-01

    In aqueous solutions, the alkali metals ions are associated with a number of H2O molecules. A distinction is made between a primary solvent shell, (or inner solvation shell), consisting of H2O molecules directly coordinated to the metal ion, and a secondary (or outer) solvation shell, consisting....... The solvation of alkali metal ions has been discussed for many years without a clear consensus. This work presents a systematic study of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS...

  18. Adsorption of Heavy Metal Ions from Aqueous Solutions by Bentonite Nanocomposites.

    Science.gov (United States)

    Ma, Jing; Su, Guojun; Zhang, Xueping; Huang, Wen

    2016-08-01

    A series of bentonite nanocomposites have been synthesized by modifying bentonite with hexadecyltrimethylammonium bromide (CTMAB) and the common complexing agents, complexone (ethylene diamine tetraacetic acid, EDTA) or mercaptocomplexant (2-Mercaptobenzothiazole, MBT). These adsorbents are used to remove heavy metal ions (Cu(2+), Zn(2+), Mn(2+),Co(2+)). The Bent-CTMAB-MBT adsorbed metal ions are higher than Bent-CTMAB-EDTA under the same ion concentration in AAS. Compared with the single ion system, the adsorption of the mixed ion system of Cu(2+), Zn(2+), Mn(2+), Co(2+) had decreased differently. In the mixed system, the adsorption of Mn(2+) is significantly lower, but the adsorption of Cu(2+) was highest. The adsorption sequence of these four metal ions was Cu(2+) > Zn(2+) > Co(2+) > Mn(2+), and the selective adsorption was closely related to the hydration energy of heavy metal ions. We could remove more metal ions in different stages with the adsorption sequence.

  19. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    International Nuclear Information System (INIS)

    Lu, Yi

    2003-01-01

    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

  20. Endonuclease active site plasticity allows DNA cleavage with diverse alkaline Earth and transition metal ions.

    Science.gov (United States)

    Vasu, Kommireddy; Saravanan, Matheshwaran; Nagaraja, Valakunja

    2011-09-16

    A majority of enzymes show a high degree of specificity toward a particular metal ion in their catalytic reaction. However, Type II restriction endonuclease (REase) R.KpnI, which is the first member of the HNH superfamily of REases, exhibits extraordinary diversity in metal ion dependent DNA cleavage. Several alkaline earth and transition group metal ions induce high fidelity and promiscuous cleavage or inhibition depending upon their concentration. The metal ions having different ionic radii and co-ordination geometries readily replace each other from the enzyme's active site, revealing its plasticity. Ability of R.KpnI to cleave DNA with both alkaline earth and transition group metal ions having varied ionic radii could imply utilization of different catalytic site(s). However, mutation of the invariant His residue of the HNH motif caused abolition of the enzyme activity with all of the cofactors, indicating that the enzyme follows a single metal ion catalytic mechanism for DNA cleavage. Indispensability of His in nucleophile activation together with broad cofactor tolerance of the enzyme indicates electrostatic stabilization function of metal ions during catalysis. Nevertheless, a second metal ion is recruited at higher concentrations to either induce promiscuity or inhibit the DNA cleavage. Regulation of the endonuclease activity and fidelity by a second metal ion binding is a unique feature of R.KpnI among REases and HNH nucleases. The active site plasticity of R.KpnI opens up avenues for redesigning cofactor specificities and generation of mutants specific to a particular metal ion.

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

    Science.gov (United States)

    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)

  2. Encapsulation of Metal Cations by the PhePhe Ligand: A Cation-pi Ion Cage

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Oomens, J.

    2011-01-01

    Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba2+ and Ca2+, the alkali-metal ions Li+, Na+, K+, and Cs+, and the transition-metal ion Ag+. The two neighboring aromatic side chains open the possibility of a

  3. Chirality-induced conformational preferences in peptide-metal ion binding revealed by IR spectroscopy

    NARCIS (Netherlands)

    Dunbar, R.C.; Steill, J.D.; Oomens, J.

    2011-01-01

    Chirality reversal of a residue in a peptide can change its mode of binding to a metal ion, as shown here experimentally by gas-phase IR spectroscopy of peptide−metal ion complexes. The binding conformations of Li+, Na+, and H+ with the ll and dl stereoisomers of PhePhe were compared through IR ion

  4. Chirality-Induced Conformational Preferences in Peptide-Metal Ion Binding Revealed by IR Spectroscopy

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Oomens, J.

    2011-01-01

    Chirality reversal of a residue in a peptide can change its mode of binding to a metal ion, as shown here experimentally by gas-phase IR spectroscopy of peptide metal ion complexes. The binding conformations of Li+, Na+, and H+ with the LL and DL stereoisomers of PhePhe were compared through IR ion

  5. Encapsulation of metal cations by the PhePhe ligand: a cation-pi ion cage

    NARCIS (Netherlands)

    Dunbar, R.C.; Steill, J.D.; Oomens, J.

    2011-01-01

    Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba2+ and Ca2+, the alkali-metal ions Li+, Na+, K+, and Cs+, and the transition-metal ion Ag+. The two neighboring aromatic side chains open the possibility of a

  6. The effect of carbamide peroxide treatment on metal ion release from dental amalgam.

    Science.gov (United States)

    Al-Salehi, S K; Hatton, P V; Miller, C A; Mcleod, C; Joiner, A

    2006-10-01

    There is concern that hydrogen peroxide generated by tooth bleaching agents may cause enhanced metal ion release (including mercury) from dental amalgam following contact. The aim of this in vitro study was therefore to investigate the effect of a carbamide peroxide (CP) based tooth bleaching gel on metal ion release from dental amalgam. Dental amalgam discs were prepared according to the manufacturers' instructions. These were treated with either a 10% carbamide peroxide (CP) gel or a 0% CP gel for 24h. Discs were carefully wiped with cotton wool before immersion in distilled water (20 ml) for 24h at 37 degrees C. Following immersion, water samples were taken for metal ion release determination (Ag, Cu, Hg and Sn) using inductively coupled plasma mass spectrometry methods. The specimens were further evaluated for surface changes using scanning electron microscopy (SEM) and Talysurf surface roughness measurements. The differences in concentration of metal ions released after treatment with the 10% CP gel and a placebo gel treatment were not statistically significant (p>0.05). For example, mercury release following treatment with the 10% CP gel and the 0% CP gel was found to be 1.17(0.5) and 0.57(0.1)microgcm(-2), respectively. Roughness measurements for samples treated with the 10% CP gel and 0% CP gel were 2.23(0.47) and 1.74(0.16)microm, respectively, again showing no significant difference between groups (p>0.05). SEM images of the amalgam surfaces showed no apparent differences between treatments. Treatment with a 10% CP gel did not significantly enhance subsequent metal ion release from dental amalgams compared to a control gel, contradicting previously published studies.

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

    Science.gov (United States)

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

    2011-10-15

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

  8. Modification of solid surface by intense pulsed light-ion and metal-ion beams

    Science.gov (United States)

    Nakagawa, Y.; Ariyoshi, T.; Hanjo, H.; Tsutsumi, S.; Fujii, Y.; Itami, M.; Okamoto, A.; Ogawa, S.; Hamada, T.; Fukumaru, F.

    1989-03-01

    Metal surfaces of Al, stainless-steel and Ti were bombarded with focused intense pulsed proton and carbon ion beams (energy ˜ 80 keV, current density ≲ 1000 A/cm 2, pulse width ˜ 300 ns). Thin titanium carbide layers were produced by carbon-ion irradiation on the titanium surface. The observed molten surface structures and recrystallized layer (20 μm depth) indicated that the surfaces reached high temperatures as a result of the irradiation. The implantation of intense pulsed metal ion beams (Al +, ˜ 20 A/cm 2) with simultaneous deposition of anode metal vapor on Ti and Fe made a mixed layer of AlTi and AlFe of about 0.5 μm depth. Ti and B multilayered films evaporated on glass substrates were irradiated by intense pulsed proton beams of relatively lower current density (10-200 A/cm 2). Ti films containing B atoms above 10 at.% were obtained. When the current density was about 200 A/cm 2 diffraction peaks of TiB 2 appeared.

  9. Systems and Methods for Fabricating Structures Including Metallic Glass-Based Materials Using Low Pressure Casting

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Kennett, Andrew (Inventor)

    2018-01-01

    Systems and methods to fabricate objects including metallic glass-based materials using low-pressure casting techniques are described. In one embodiment, a method of fabricating an object that includes a metallic glass-based material includes: introducing molten alloy into a mold cavity defined by a mold using a low enough pressure such that the molten alloy does not conform to features of the mold cavity that are smaller than 100 microns; and cooling the molten alloy such that it solidifies, the solid including a metallic glass-based material.

  10. Formation of negative ions on a metal surface

    International Nuclear Information System (INIS)

    Amersfoort, P.W. van.

    1987-01-01

    In this thesis a fundamental study of the charge exchange process of positive ions on the converter surface is presented. Beams of hydrogen ad cesium ions are scattered from a thoroughly cleaned W(110) surface, under ultra-high vacuum conditions. The cesium coverage of the surface is a controlled parameter. Ch. 2 deals with the negative-ion formation probability for hydrogen atoms. The influence of coabsorption of hydrogen is studied in Ch. 3. These measurements are important for understanding the formation process in plasma sources, because the converter surface is expected to be strongly contaminated with hydrogen. The charge state of scattered cesium particles is investigated in Ch. 4. Knowledge of this parameter is essential for Ch. 5, in which a model study of adsorption of cesium on a metal surface in contact with a plasma is presented. Finally, the negative-ion formation process in a plasma environment is studied in Ch. 6. Measurements done on a hollow-cathode discharge equipped with a novel type of converter, a porous tungsten button, are discussed. Liquid cesium diffuses through this button towards the side in contact with the plasma. (Auth.)

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  12. Sensitive metal ions (II) determination with resonance Raman method

    Science.gov (United States)

    Yu, Zhi; Bracero, Lucas A.; Chen, Lei; Song, Wei; Wang, Xu; Zhao, Bing

    2013-03-01

    In this paper, a new proposal for the quantitative evaluation of divalent metal ions (M2+) is developed by the use of the competitive resonance Raman (RR)-based method. Upon excitation with light of the appropriate wavelength (532 nm), a strong electric field is generated that couples with the resonance of the complex (zincon-M2+), increasing the character signals of these complexes, resulting in sensitive detection. Herein, the RR probe, zincon-M2+ complex that the RR intensity gets lower with the decreasing of the M2+ concentration, which leads to the transformation of the Raman information. As a result, by using the proposed RR-based method, we could find the liner calibration curves of Cu2+ and Ni2+, which show the potential in quantitative evaluation of an unknown sample. In addition, the abundant fingerprint information shows that RR leads to the successful analysis of a blended solution, which contains two ions: Cu2+ and Ni2+.

  13. Measuring free metal ion concentrations in situ in natural waters using the Donnan Membrane Technique

    NARCIS (Netherlands)

    Kalis, E.J.J.; Weng, L.P.; Dousma, F.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

    2006-01-01

    Metal toxicity is not related to the total but rather to the free or labile metal ion concentration. One of the techniques that can be used to measure several free metal ion concentrations simultaneously is the Donnan Membrane Technique (DMT) in combination with the inductively coupled plasma-mass

  14. PHENOL OXIDATION USING NATURAL ZEOLITE SUPPORTED METAL ION CATALYST

    Directory of Open Access Journals (Sweden)

    Sri Wardhani

    2010-06-01

    Full Text Available Phenol which contained in waste water has to be reduced and it could be done by oxygen oxidation.  In order to increase the rate of reaction it was needed a catalyst. In this research the capability of various catalysts, namely zeolite-Zn(II, zeolite-Cu(II and zeolite-Co(IIin oxidation of phenol has been investigated. The aim of this research was to study the type of metal ion catalyst towards the percentage of oxidated phenol. The oxidation process were carried out in an aqueous phenol of 100 ppm with oxygen flow rate of 200 mL/min. in the presence of catalysts with 0.2M of initial impregnation concentration. The capabilities of catalysts were performed by calculating the activation energy and it was done at two different temperatures, i.e. 70 and 90 oC. The percentage of oxidated phenol was determinated by measuring its concentration using UV-VIS spectrophotometer. In addition, the impregnated metal was calculated by measuring the ion concentration remains in the filtrate solution and it was determined using Atomic Absorption Spectrophotometer. The results showed that metal ion types affected the catalytic activity. The order of phenol oxidationactivity decreased as Co(II > Cu(II > Zn(II. The surface characteristics of catalysts were supported by pore volume and pore diameter i.e 0.009 cm3/g and 16.59 Å for Zn(II whereas specific surface area was 10.32 m2/g for Zn(II, 0.004 cm3/g and 24.37 Å for Cu(II whereas specific surface area was 3.57 m2/g for Cu(II, 0.001 cm3/g and 19.63 Å for Co(II whereas specific surface area was 10.26m2/g for Co(II.   Keywords: phenol,natural zeolite, catalyst, oxidation

  15. Industrial applications of ion implantation into metal surfaces

    International Nuclear Information System (INIS)

    Williams, J.M.

    1987-07-01

    The modern materials processing technique, ion implantation, has intriguing and attractive features that stimulate the imaginations of scientists and technologists. Success of the technique for introducing dopants into semiconductors has resulted in a stable and growing infrastructure of capital equipment and skills for use of the technique in the economy. Attention has turned to possible use of ion implantation for modification of nearly all surface related properties of materials - optical, chemical and corrosive, tribological, and several others. This presentation provides an introduction to fundamental aspects of equipment, technique, and materials science of ion implantation. Practical and economic factors pertaining to the technology are discussed. Applications and potential applications are surveyed. There are already available a number of ion-implanted products, including ball-and-roller bearings and races, punches-and-dies, injection screws for plastics molding, etc., of potential interest to the machine tool industry

  16. Local coordination of polyvalent metal ions in molten halide mixtures

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Tosi, M.P.

    1989-07-01

    Ample experimental evidence is available in the literature on the geometry and the stability of local coordination for polyvalent metal ions in molten mixtures of their halides with alkali halides. Recent schemes for classifying this evidence are discussed. Dissociation of tetrahedral halocomplexes in good ionic systems can be viewed as a classical Mott problem of bound-state stability in a conducting matrix. More generally, structural coordinates can be constructed from properties of the component elements, to separate out systems with long-lived fourfold or sixfold coordination and to distinguish between these. (author). 11 refs, 1 fig

  17. Studies on the dryolysis reactions of metal ions

    International Nuclear Information System (INIS)

    Baes, C.F. Jr.

    1977-01-01

    Research is reported on metallic ions produced in solutions at low concentrations as mononuclear hydrolysis products. The method for studying the mononuclear species is to measure the solubility of the oxide or hydroxide solid phase that is stable under the conditions of interest. Column solubility measurements of Al(OH) 3 (Gibbsite) in NaCl solution as a function of pH, temperature, and ionic strength are being conducted in order to better establish the stability of the intermediate species Al(OH) 2 + and Al(OH) 3 (aq)

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

    International Nuclear Information System (INIS)

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

    1999-01-01

    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

  19. Metal ion interaction of an oligopeptide fragment representing the regulatory metal binding site of a CueR protein

    DEFF Research Database (Denmark)

    Jancsó, Attila; Szokolai, Hajnalka; Roszahegyi, Livia

    2013-01-01

    Metalloregulatory proteins of the MerR family are transcriptional activators that sense/control the concentration of various metal ions inside bacteria.1 The Cu+ efflux regulator CueR, similarly to other MerR proteins, possesses a short multiple Cys-containing metal binding loop close to the C......-terminus. CueR has a high selectivity for Cu+, Ag+ and Au+, but exhibits no transcriptional activity for the divalent ions Hg2+ and Zn2+.2 The two Cys- residues of the metal binding loop were shown to settle M+ ions into a linear coordination environment but other factors may also play a role in the recognition...... of cognate metal ions.2 Nevertheless, it is an interesting question whether the same sequence, when removed from the protein, shows a flexibility to adopt different coordination environments and may efficiently bind metal ions having preferences for larger coordination numbers....

  20. Novel forward osmosis process to effectively remove heavy metal ions

    KAUST Repository

    Cui, Yue

    2014-10-01

    In this study, a novel forward osmosis (FO) process for the removal of heavy metal ions from wastewater was demonstrated for the first time. The proposed FO process consists of a thin-film composite (TFC) FO membrane made from interfacial polymerization on a macrovoid-free polyimide support and a novel bulky hydroacid complex Na4[Co(C6H4O7)2]·r2H2O (Na-Co-CA) as the draw solute to minimize the reverse solute flux. The removal of six heavy metal solutions, i.e., Na2Cr2O7, Na2HAsO4, Pb(NO3)2, CdCl2, CuSO4, Hg(NO3)2, were successfully demonstrated. Water fluxes around 11L/m2/h (LMH) were harvested with heavy metals rejections of more than 99.5% when employing 1M Na-Co-CA as the draw solution to process 2000ppm(1 ppm=1 mg/L) heavy metal solutions at room temperature. This FO performance outperforms most nanofiltration (NF) processes. In addition, the high rejections were maintained at 99.5% when a more concentrated draw solution (1.5M) or feed solution (5000ppm) was utilized. Furthermore, rejections greater than 99.7% were still achieved with an enhanced water flux of 16.5LMH by operating the FO process at 60°C. The impressive heavy metal rejections and satisfactory water flux under various conditions suggest great potential of the newly developed FO system for the treatment of heavy metal wastewater. © 2014 Elsevier B.V.

  1. Adverse reaction to metal debris in a consecutive series of DUROM™ hip resurfacing: pseudotumour incidence and metal ion concentration.

    Science.gov (United States)

    Hartmann, Albrecht; Kieback, Jan-Dirk; Lützner, Jörg; Günther, Klaus-Peter; Goronzy, Jens

    2017-07-25

    The aim of this study was to evaluate the incidence of adverse reactions to metal debris (ARMD) in a consecutive series of DUROM™ Hip Resurfacing Arthroplasty (HRA) at mid-term follow-up. Between October 2003 and March 2007 a total of 134 consecutive DUROM™ HRA in 121 patients were performed at our institution. Follow-up could be obtained in 101 unrevised patients (83%) at a mean time of 8.51 ± 0.97 years postoperatively and included patient-related outcome measurement, plain radiographs, MARS-MRI as well as whole blood metal ion assessment. 17 (16.5%) out of 103 hips revealed pseudotumour occurrence in MRI investigation, 1 (10.6%) with a diameter of ≥2 cm. Higher incidence of pseudotumours was found patients with femoral component size 7 μg/l. In contrast to cobalt determination, only elevated chromium values showed a positive association with pseudotumour occurrence and size. A significant proportion of patients developed pseudotumours and metal ion elevation in a consecutive cohort of DUROM™ HRA after mid-term follow-up. The incidence, however, seems not to differ from results of other well performing resurfacing brands; clinical relevance of our findings is unclear. Regarding potential local as well as systemic effects of metal particle release, close follow-up of patients is essential, even with clinically well-performing implants.

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

    Science.gov (United States)

    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.

  3. Acetabular bone density and metal ions after metal-on-metal versus metal-on-polyethylene total hip arthroplasty; short-term results

    NARCIS (Netherlands)

    Zijlstra, Wierd P.; van der Veen, Hugo C.; van den Akker-Scheek, Inge; Zee, Mark J. M.; Bulstra, Sjoerd K.; van Raay, Jos J. A. M.

    Information on periprosthetic acetabular bone density is lacking for metal-on-metal total hip arthroplasties. These bearings use cobalt-chromium instead of titanium acetabular components, which could lead to stress shielding and hence periprosthetic bone loss. Cobalt and chromium ions have

  4. Metal ion detection with oligo(ethylene glycol) monolayer-modified gold nanoparticles.

    Science.gov (United States)

    Li, Guangzhao; Yang, Bin; Lu, Zhiqiang; Xia, Sijing; Feng, Hui; Zhu, Xiaoqing; Wang, Anning; Zhu, Jin

    2011-11-01

    Two colorimetric sensors of gold nanoparticles (AuNPs) modified with different oligo(ethylene glycol)-containing organic molecules have been developed to detect metal ions by ultraviolet-visible (UV-vis) extinction spectroscopy. These sensors display different responses to some metal ions. One exhibits high selectivity for Hg2+ over a variety of competitive metal ions and the other one can respond to a multitude of metal ions. These differences might result from the different functionalized end groups of the modified molecules. Coordination effect, pH response, and ionic strength were investigated to understand the mechanism of the responses to metal ions. The results suggested that the colorimetric responses were mainly induced by the coordination effect of the modified organic molecules and the removing of the modified organic molecules caused by metal ions.

  5. Architectural design criteria for f-block metal ion sequestering agents. 1998 annual progress report

    International Nuclear Information System (INIS)

    Dixon, D.A.; Hay, B.P.; Paine, R.T.; Raymond, K.N.; Rogers, R.D.; Roundhill, D.M.

    1998-01-01

    'The objective of this project is to provide a means to optimize ligand architecture for f-block metal recognition. The authors strategy builds on an innovative and successful molecular modeling approach in developing polyether ligand design criteria for the alkali and alkaline earth cations. The hypothesis underlying this proposal is that differences in metal ion binding with multidentate ligands bearing the same number and type of donor groups are primarily attributable to intramolecular steric factors. They propose quantifying these steric factors through the application of molecular mechanics models. The research involves close integration of theoretical and experimental chemistry. The experimental work entails synthesizing novel ligands and experimentally determining structures and binding constants for metal ion complexation by series of ligands in which architecture is systematically varied. The theoretical work entails using electronic structure calculations to parameterize a molecular mechanics force field for a range of metal ions and ligand types. The resulting molecular mechanics force field will be used to predict low energy structures for unidentate, bidentate, and multidentate ligands and their metal complexes through conformational searches. Results will be analyzed to assess the relative importance of several steric factors including optimal M-L length, optimal geometry at the metal center, optimal geometry at the donor atoms (complementarity), and conformation prior to binding (preorganization). An accurate set of criteria for the design of ligand architecture will be obtained from these results. These criteria will enable researchers to target ligand structures for synthesis and thereby dramatically reduce the time and cost associated with metal-specific ligand development.'

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jia; Whangbo, Myung-Hwan, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695 (United States); Koo, Hyun-Joo [Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Xiang, Hongjun, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433 (China); Kremer, Reinhard K. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    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.

  7. Enhancing glycan isomer separations with metal ions and positive and negative polarity ion mobility spectrometry-mass spectrometry analyses

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Xueyun; Zhang, Xing; Schocker, Nate; Renslow, Ryan S.; Orton, Daniel J.; Khamsi, Jamal; Ashmus, Roger A.; Almeida, Igor C.; Tang, Keqi; Costello, Catherine E; Smith, Richard D.; Michael, Katja; Baker, Erin M.

    2016-09-07

    Glycomics has become an increasingly important field of research since glycans play critical roles in biology processes ranging from molecular recognition and signaling to cellular communication. Glycans often conjugate with other biomolecules such as proteins and lipids, and alter their properties and functions, so understanding the effect glycans have on cellular systems is essential. However the analysis of glycans is extremely difficult due to their complexity and structural diversity (i.e., the number and identity of monomer units, and configuration of their glycosidic linkages and connectivities). In this work, we coupled ion mobility spectrometry with mass spectrometry (IMS-MS) to characterize glycan standards and biologically important isomers of synthetic αGal-containing O-glycans including glycotopes of the protozoan parasite Trypanosoma cruzi, which is the causative agent of Chagas disease. IMS-MS results showed significant differences for the glycan structural isomers when analyzed in positive and negative polarity and complexed with different metal cations. These results suggest specific metal ions or ion polarities could be used to target and baseline separate glycan isomers of interest with IMS-MS.

  8. Magnetic nanoparticle based solid-phase extraction of heavy metal ions: A review on recent advances.

    Science.gov (United States)

    Hemmati, Maryam; Rajabi, Maryam; Asghari, Alireza

    2018-02-06

    This review (with 151 refs) focuses on recent progress that has been made in magnetic nanoparticle-based solid phase extraction (SPE), pre-concentration and speciation of heavy metal ions. In addition, it discusses applications to complex real samples such as environmental, food, and biological matrices. The introduction addresses current obstacles and limitations associated with established SPE approaches and discusses the present state of the art in different formats of off-line and on-line SPE. The next section covers magnetized inorganic nanomaterials for use in SPE, with subsections on magnetic silica, magnetic alumina and titania, and on magnetic layered double oxides. A further section treats magnetized carbonaceous nanomaterials for use in SPE, with subsections on magnetic graphene and/or graphene oxides, magnetic carbon nanotubes and magnetic carbon nitrides. We then discuss the progress made in SPE based on the use of magnetized organic polymers (mainly non-imprinted and ion-imprinted polymer). This is followed by shorter sections on the use of magnetized metal organic frameworks, magnetized ionic liquids and magnetized biosorbents. All sections include discussions of the nanomaterials in terms of selectivity, sorption capacity, mechanisms of sorption and common routes for material synthesis. A concluding section addresses actual challenges and discusses perspective routes towards further improvements. Graphical abstract An overview on booster nanomaterials (ionic liquids, inorganic, organic and biological materials, and metal-organic frameworks) for use in magnetic nanoparticle-based solid-phase extraction of heavy metal ions.

  9. Sensitivity to Heavy-Metal Ions of Unfolded Fullerene Quantum Dots

    Directory of Open Access Journals (Sweden)

    Erica Ciotta

    2017-11-01

    Full Text Available A novel type of graphene-like quantum dots, synthesized by oxidation and cage-opening of C60 buckminsterfullerene, has been studied as a fluorescent and absorptive probe for heavy-metal ions. The lattice structure of such unfolded fullerene quantum dots (UFQDs is distinct from that of graphene since it includes both carbon hexagons and pentagons. The basic optical properties, however, are similar to those of regular graphene oxide quantum dots. On the other hand, UFQDs behave quite differently in the presence of heavy-metal ions, in that multiple sensitivity to Cu2+, Pb2+ and As(III was observed through comparable quenching of the fluorescent emission and different variations of the transmittance spectrum. By dynamic light scattering measurements and transmission electron microscope (TEM images we confirmed, for the first time in metal sensing, that this response is due to multiple complexation and subsequent aggregation of UFQDs. Nonetheless, the explanation of the distinct behaviour of transmittance in the presence of As(III and the formation of precipitate with Pb2+ require further studies. These differences, however, also make it possible to discriminate between the three metal ions in view of the implementation of a selective multiple sensor.

  10. Effects of heavy metal ions on EDTA-sensitive cell contacts of Dictyostelium discoideum

    OpenAIRE

    Yoshida, Motonobu

    2000-01-01

    [Synopsis] The effects of heavy metal ions on the EDTA-sensitive cell contacts, which exist from growthphase stage of Dictyostelium discoideum, was investigated. EDTA-sensitive cell contacts of cells at the growth-phase stage were analyzed in the presence of heavy metal ions. Heavy metal ions Hg^, Cd^ and Cu^ inhibited EDTA-sensitive cell contacts at concentrations higher than 10^M, whereas Pb^ did not show any recognizable effects at the same concentration range. The possible mechanisms of a...

  11. Three Metal Ions Participate in the Reaction Catalyzed by T5 Flap Endonuclease*S⃞

    Science.gov (United States)

    Syson, Karl; Tomlinson, Christopher; Chapados, Brian R.; Sayers, Jon R.; Tainer, John A.; Williams, Nicholas H.; Grasby, Jane A.

    2008-01-01

    Protein nucleases and RNA enzymes depend on divalent metal ions to catalyze the rapid hydrolysis of phosphate diester linkages of nucleic acids during DNA replication, DNA repair, RNA processing, and RNA degradation. These enzymes are widely proposed to catalyze phosphate diester hydrolysis using a “two-metal-ion mechanism.” Yet, analyses of flap endonuclease (FEN) family members, which occur in all domains of life and act in DNA replication and repair, exemplify controversies regarding the classical two-metal-ion mechanism for phosphate diester hydrolysis. Whereas substrate-free structures of FENs identify two active site metal ions, their typical separation of >4 Å appears incompatible with this mechanism. To clarify the roles played by FEN metal ions, we report here a detailed evaluation of the magnesium ion response of T5FEN. Kinetic investigations reveal that overall the T5FEN-catalyzed reaction requires at least three magnesium ions, implying that an additional metal ion is bound. The presence of at least two ions bound with differing affinity is required to catalyze phosphate diester hydrolysis. Analysis of the inhibition of reactions by calcium ions is consistent with a requirement for two viable cofactors (Mg2+ or Mn2+). The apparent substrate association constant is maximized by binding two magnesium ions. This may reflect a metal-dependent unpairing of duplex substrate required to position the scissile phosphate in contact with metal ion(s). The combined results suggest that T5FEN primarily uses a two-metal-ion mechanism for chemical catalysis, but that its overall metallobiochemistry is more complex and requires three ions. PMID:18697748

  12. Electrospray droplet exposure to organic vapors: metal ion removal from proteins and protein complexes.

    Science.gov (United States)

    DeMuth, J Corinne; McLuckey, Scott A

    2015-01-20

    The exposure of aqueous nanoelectrospray droplets to various organic vapors can dramatically reduce sodium adduction on protein ions in positive ion mass spectra. Volatile alcohols, such as methanol, ethanol, and isopropanol lead to a significant reduction in sodium ion adduction but are not as effective as acetonitrile, acetone, and ethyl acetate. Organic vapor exposure in the negative ion mode, on the other hand, has essentially no effect on alkali ion adduction. Evidence is presented to suggest that the mechanism by which organic vapor exposure reduces alkali ion adduction in the positive mode involves the depletion of alkali metal ions via ion evaporation of metal ions solvated with organic molecules. The early generation of metal/organic cluster ions during the droplet desolvation process results in fewer metal ions available to condense on the protein ions formed via the charged residue mechanism. These effects are demonstrated with holomyoglobin ions to illustrate that the metal ion reduction takes place without detectable protein denaturation, which might be revealed by heme loss or an increase in charge state distribution. No evidence is observed for denaturation with exposure to any of the organic vapors evaluated in this work.

  13. Effect of carbon ion implantation on the tribology of metal-on-metal bearings for artificial joints

    Directory of Open Access Journals (Sweden)

    Koseki H

    2017-05-01

    Full Text Available Hironobu Koseki,1 Masato Tomita,2 Akihiko Yonekura,2 Takashi Higuchi,1 Sinya Sunagawa,2 Koumei Baba,3,4 Makoto Osaki2 1Department of Locomotive Rehabilitation Science, Unit of Rehabilitation Sciences, 2Department of Orthopedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto, Nagasaki, Japan; 3Industrial Technology Center of Nagasaki, Ikeda, Omura, Nagasaki, Japan; 4Affiliated Division, Nagasaki University School of Engineering, Bunkyo, Nagasaki, Japan Abstract: Metal-on-metal (MoM bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa, a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and

  14. Evaluation of cationite efficiency during extraction of heavy metal ions from diluted solutions

    OpenAIRE

    Gomelya, Nikolai; Ivanova, Veronika; Galimova, Valentina; Nosachova, Julia; Shabliy, Tatiana

    2017-01-01

    Ion exchange is one of the methods that has been successfully employed in industry for extracting heavy metals from wastewater. We conducted research into ion-exchange processes of extraction of heavy metal ions on the weak- and strong-acid cationites from distilled and tap water. Heavy metal ion concentration was less than 1 mg/dm3. We established that in all cases efficiency of water treatment decreased at a decrease in the starting concentration of a metal. The process took place regardles...

  15. Application of monocarboxylic acids for the extraction of metal ions-literature survey

    International Nuclear Information System (INIS)

    Brzozka, Z.; Rozycki, C.

    1980-01-01

    In the paper there is presented a literature review concerning the application of monocarboxylic acids for extraction of metal ions. The following problems are discussed: characteristic of monocarboxylic acids and their mixtures, the equilibria between the acid solution in organic solvent and aqueous phase, the mechanism of acid partition, complexes of carboxylic acids and metal ions in aqueous phase, mechanism of extraction by means of carboxylic acids as well as the problems concerning the extraction of individual metal ions. Data about the extraction of metal ions are presented in table. The 138 references are given. (author)

  16. Use of divalent metal ions in the DNA cleavage reaction of topoisomerase IV

    Science.gov (United States)

    Pitts, Steven L.; Liou, Grace F.; Mitchenall, Lesley A.; Burgin, Alex B.; Maxwell, Anthony; Neuman, Keir C.; Osheroff, Neil

    2011-01-01

    It has long been known that type II topoisomerases require divalent metal ions in order to cleave DNA. Kinetic, mutagenesis and structural studies indicate that the eukaryotic enzymes utilize a novel variant of the canonical two-metal-ion mechanism to promote DNA scission. However, the role of metal ions in the cleavage reaction mediated by bacterial type II enzymes has been controversial. Therefore, to resolve this critical issue, this study characterized the DNA cleavage reaction of Escherichia coli topoisomerase IV. We utilized a series of divalent metal ions with varying thiophilicities in conjunction with oligonucleotides that replaced bridging and non-bridging oxygen atoms at (and near) the scissile bond with sulfur atoms. DNA scission was enhanced when thiophilic metal ions were used with substrates that contained bridging sulfur atoms. In addition, the metal-ion dependence of DNA cleavage was sigmoidal in nature, and rates and levels of DNA cleavage increased when metal ion mixtures were used in reactions. Based on these findings, we propose that topoisomerase IV cleaves DNA using a two-metal-ion mechanism in which one of the metal ions makes a critical interaction with the 3′-bridging atom of the scissile phosphate and facilitates DNA scission by the bacterial type II enzyme. PMID:21300644

  17. Nanoparticles reduce nickel allergy by capturing metal ions

    Science.gov (United States)

    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.

  18. Accelerated electron exchange between U4+ and UO22+ by foreign metal ions

    International Nuclear Information System (INIS)

    Obanawa, Heiichiro; Onitsuka, Hatsuki; Takeda, Kunihiko

    1990-01-01

    The rate constant of U 4+ -UO 2 2+ electron exchange (k et ) was increased by more than 100 times in the presence of various metal ions. The larger rate constant was observed for the smaller difference of the standard reduction potential strength between metal ion and UO 2 2+ ion (Δμ θ e ). Detailed investigation of the electron exchange reaction in the presence of Mo 5+ suggested that the mechanism of the electron transfer reaction catalyzed by metal ions is the outer-sphere type independent of U-Clcomplex ions. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Prostate cancer outcome and tissue levels of metal ions

    Science.gov (United States)

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

    2011-01-01

    BACKGROUNDThere 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.METHODSWe 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.RESULTSPatients with biochemical (PSA) recurrence of disease had 12% lower median iron (95 µg/g vs. 111 µg/g; P = 0.04) and 21% lower zinc (279 µg/g vs. 346 µg/g; P = 0.04) concentrations in the normal-appearing tissue immediately adjacent to cancer areas. Differences in cadmium (0.489 µg/g vs. 0.439 µg/g; 4% higher) and selenium (1.68 µg/g vs. 1.58 µg/g; 5% higher) levels were not statistically significant in recurrence cases, when compared to non-recurrences (P = 0.40 and 0.21, respectively).CONCLUSIONSThere 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. 

  1. Metal carbonates as anode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Shao, Lianyi; Ma, Rui; Wu, Kaiqiang; Shui, Miao; Lao, Mengmeng; Wang, Dongjie; Long, Nengbing; Ren, Yuanlong; Shu, Jie

    2013-01-01

    Highlights: •Metal carbonates are probable anode materials for lithium ion batteries. •CoCO 3 /C composite can deliver an initial discharge capacity of 2096.6 mAh g −1 . •Co, Li 2 CO 3 , Li 2 O, and low-valence carbon are final lithiated products for CoCO 3 . -- Abstract: Six metal carbonates (Li 2 CO 3 , Na 2 CO 3 , SrCO 3 , BaCO 3 , K 2 CO 3 , CoCO 3 ) are tested and compared as anode materials for lithium ion batteries. The electrochemical results show that only CoCO 3 is electrochemically active material and can deliver a high initial capacity of 1425.9 mAh g −1 . The lithium storage mechanism in CoCO 3 is studied by ex situ X-ray diffraction technique, ex situ infrared method, ex situ X-ray photoelectron spectroscopy and in situ X-ray diffraction technique. It is found that the electrochemical reactions between CoCO 3 and Li firstly result in the formation of metal Co and Li 2 CO 3 , and then partial Li 2 CO 3 is further reduced into carbon (C 0 ), low-valence carbon (C 2+ ), and Li 2 O. It also demonstrates that the electrochemical reaction between CoCO 3 and Li is a partially reversible process. Based on these electrochemical results, it is obvious that narrow potential range can acquire a better reversibility for CoCO 3 /Li batteries by suppressing particle pulverization. Besides, the comparison of CoCO 3 , ball-milled CoCO 3 and ball-milled CoCO 3 /C composite also indicates that smaller active particle and carbon buffer are beneficial to obtain better cycling performance and higher reversible capacity

  2. Biosorption of Heavy Metal Ions to Brown Algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida

    OpenAIRE

    Seki, Hideshi; Suzuki, Akira

    1998-01-01

    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 ...

  3. Heavy metal ion removal by adsorption on to biological materials

    International Nuclear Information System (INIS)

    Jansson-Charrier, M.; Guibal, E.; Le Cloirec, P.; Surjous, R.

    1994-01-01

    The development of regulations constraints in the industrial waste-waters management leads to the study of new treatment processes, using raw or functionalized biological materials. These processes show competitive performances in metal ion sorption efficiency for the low metal content effluents. Uptake capacities of Uranium as high as 400 mg.g -1 chitosan, equivalent to the double of the uptake capacity of fungal origin biomass, can be reached. The application of these processes to real mine wastewaters gives efficiency coefficient upper to 90%, the residual concentrations are compatible to a direct injection into the environment. The grafting of functional groups onto the chitosan scales up the sorption performances to uptake capacity upper than 600 mg.g -1 polymer. pH, metal concentration are cited as major parameters, particle size influences both uptake kinetics and sorption equilibrium, in the case of the uranium accumulation by chitosan. The desorption of uranium from the sorbent allows the valorization of uranium and the re-use of the sorbent. (authors). 21 refs., 10 figs

  4. Outcome of revision arthroplasty for failed metal-on-metal total hip replacements; is there a relation with metal ions?

    Science.gov (United States)

    Iqbal, Hafiz J; Al-Azzani, Waheeb A K; Jackson-Taylor, Esther; Clatworthy, Elizabeth; John, Alun

    2017-05-12

    We aimed to assess the early outcome following revision arthroplasty for failed metal-on-metal (MoM) total hip replacements (THR) due to adverse reaction to metal debris (ARMD). We reviewed 106 consecutive revision arthroplasties. Case notes and radiological investigations were reviewed to assess the complications. Oxford Hip Score (OHS) and Euroqol (EQ-5D-3L) scores were used to assess the functional outcome and improvement of quality of life. At a mean follow-up of 20 months (12-48 months), the mean OHS was 28.7. Pain improved in 61% patients. A majority of patients were in level 2 for all the EQ-5D-3L dimensions. The overall complication rate was 16%. Survivorship free from further revision for any cause was 94.3% at 48 months. There was no correlation between pre-revision blood metal ions and the final outcome. Revision surgery for failed MoM hip replacement due to ARMD is associated with a relatively higher rate of complications and risk of chronic pain. There is poor correlation between serum metal ions and development of ARMD and outcome following revision surgery.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Highlights: • Metal nanoparticles can be produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. • The nanoparticles nucleate near the maximum of the implantation depth profile, that can be estimated by computer simulation using the TRIDYN. • Nanocomposites, obtained by this way, can be produced in different insulator materials. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. • The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted, reaching the percolation threshold. • Excellent agreement was found between the experimental results and the predictions of the theory. - Abstract: There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in

  6. Thiophilic metal ion rescue of phosphorothioate interference within the Tetrahymena ribozyme P4-P6 domain.

    OpenAIRE

    Basu, S; Strobel, S A

    1999-01-01

    Divalent metal ions are essential for the folding and catalytic activities of many RNAs. A commonly employed biochemical technique to identify metal-binding sites in RNA is the rescue of Rp alpha-phosphorothioate (PS) interference by the addition of soft divalent metal ions. To access the ability of such experiments to accurately identify metal-ion coordinations within a complex RNA fold, we report metal-rescue results from the Tetrahymena group I intron P4-P6 domain, where the location and c...

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

    Science.gov (United States)

    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. Copyright © 2016. Published by Elsevier Inc.

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

    Science.gov (United States)

    Mathews, J. D.

    1987-01-01

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

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

    Science.gov (United States)

    Jäkel, Oliver; Reiss, Petra

    2007-02-01

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

  10. Thermosensitive gels incorporating polythioether units for the selective extraction of class b metal ions.

    Science.gov (United States)

    Chayama, K; Morita, Y; Iwatsuki, S

    2010-10-22

    Novel temperature-responsive copolymers of N-isopropylacrylamide and monoaza-tetrathioether derivative, were synthesized for the selective extraction of soft metal ions such as silver(I), copper(I), gold(III) and palladium(II) ion. The ratio between N-isopropylacrylamide group and monoaza-tetrathioether group in the copolymer was determined. The ratio between N-isopropylacrylamide group and monoaza-tetrathioether group varied in the range of 66:1-187:1. Each lower critical solution temperature (LCST) of the polymer solution was determined spectrophotometrically by the relative absorbance change at 750 nm via temperature of the polymer solution. Metal ion extraction using the copolymer with appropriate counter anions such as picrate ion, nitrate or perchlorate ion was examined. Soft metal ions such as silver(I), copper(I), gold(III) and palladium(II) ion were extracted selectively into the solid polymer phase. The extraction efficiency of a metal ion such as silver ion increased as the increase of the ratio of the monoaza-tetrathioether group to N-isopropylacrylamide group in the polymer. The quantitative extraction of class b metal ions as well as the liquid-liquid extraction of metal ions with monoaza-tetrathioether molecule was performed. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Metal ions, not metal-catalyzed oxidative stress, cause clay leachate antibacterial activity.

    Directory of Open Access Journals (Sweden)

    Caitlin C Otto

    Full Text Available Aqueous leachates prepared from natural antibacterial clays, arbitrarily designated CB-L, release metal ions into suspension, have a low pH (3.4-5, generate reactive oxygen species (ROS and H2O2, and have a high oxidation-reduction potential. To isolate the role of pH in the antibacterial activity of CB clay mixtures, we exposed three different strains of Escherichia coli O157:H7 to 10% clay suspensions. The clay suspension completely killed acid-sensitive and acid-tolerant E. coli O157:H7 strains, whereas incubation in a low-pH buffer resulted in a minimal decrease in viability, demonstrating that low pH alone does not mediate antibacterial activity. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to the antibacterial leachate. Further, supplementation with numerous ROS scavengers eliminated lipid peroxidation, but did not rescue the cells from CB-L-mediated killing. In contrast, supplementing CB-L with EDTA, a broad-spectrum metal chelator, reduced killing. Finally, CB-L was equally lethal to cells in an anoxic environment as compared to the aerobic environment. Thus, ROS were not required for lethal activity and did not contribute to toxicity of CB-L. We conclude that clay-mediated killing was not due to oxidative damage, but rather, was due to toxicity associated directly with released metal ions.

  12. Quantum optics including noise reduction, trapped ions, quantum trajectories, and decoherence

    CERN Document Server

    Orszag, Miguel

    2016-01-01

    This new edition gives a unique and broad coverage of basic laser-related phenomena that allow graduate students, scientists and engineers to carry out research in quantum optics and laser physics. It covers quantization of the electromagnetic field, quantum theory of coherence, atom-field interaction models, resonance fluorescence, quantum theory of damping, laser theory using both the master equation and the Langevin theory, the correlated emission laser, input-output theory with applications to non-linear optics, quantum trajectories, quantum non-demolition measurements and generation of non-classical vibrational states of ions in a Paul trap. In this third edition, there is an enlarged chapter on trapped ions, as well as new sections on quantum computing and quantum bits with applications. There is also additional material included for quantum processing and entanglement. These topics are presented in a unified and didactic manner, each chapter is accompanied by specific problems and hints to solutions to...

  13. Ion-irradiation studies of cascade damage in metals

    International Nuclear Information System (INIS)

    Averback, R.S.

    1982-03-01

    Ion-irradiation studies of the fundamental aspects of cascade damage in metals are reviewed. The emphasis of these studies has been the determination of the primary state of damage (i.e. the arrangement of atoms in the cascade region prior to thermal migration of defects). Progress has been made towards understanding the damage function (i.e. the number of Frenkel pairs produced as a function of primary recoil atom energy), the spatial configuration of vacancies and interstitials in the cascade and the cascade-induced mixing of atoms. It is concluded for these studies that the agitation of the lattice in the vicinity of energetic displacement cascades stimulates the defect motion and that such thermal spike motion induces recombination and clustering of Frenkel defects. 9 figures

  14. Molar absorption coefficients and stability constants of Zincon metal complexes for determination of metal ions and bioinorganic applications.

    Science.gov (United States)

    Kocyła, Anna; Pomorski, Adam; Krężel, Artur

    2017-11-01

    Zincon (ZI) is one of the most common chromophoric chelating probes for the determination of Zn 2+ and Cu 2+ ions. It is also known to bind other metal ions. However, literature data on its binding properties and molar absorption coefficients are rather poor, varying among publications or determined only in certain conditions. There are no systematic studies on Zn 2+ and Cu 2+ affinities towards ZI performed under various conditions. However, this widely commercially available and inexpensive agent is frequently the first choice probe for the measurement of metal binding and release as well as determination of affinity constants of other ligands/macromolecules of interest. Here, we establish the spectral properties and the stability of ZI and its complexes with Zn 2+ , Cu 2+ , Cd 2+ , Hg 2+ , Co 2+ , Ni 2+ and Pb 2+ at multiple pH values from 6 to 9.9. The obtained results show that in water solution the MZI complex is predominant, but in the case of Co 2+ and Ni 2+ , M(ZI) 2 complexes are also formed. The molar absorption coefficient at 618 nm for ZnZI and 599nm for CuZI complexes at pH7.4 in buffered (I=0.1M) water solutions are 24,200 and 26,100M -1 cm -1 , respectively. Dissociation constants of those complexes are 2.09×10 -6 and 4.68×10 -17 M. We also characterized the metal-assisted Zincon decomposition. Our results provide new and reassessed optical and stability data that are applicable to a wide range of chemical and bioinorganic applications including metal ion detection, and quantification and affinity studies of ligands of interest. Accurate values of molar absorption coefficients of Zincon complex with Zn 2+ , Cd 2+ , Hg 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Pb 2+ for rapid metal ion quantification are provided. Zincon stability constants with Zn 2+ and Cu 2+ in a wide pH range were determined. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Metal Ion Binding at the Catalytic Site Induces Widely Distributed Changes in a Sequence Specific Protein-DNA Complex.

    Science.gov (United States)

    Sinha, Kaustubh; Sangani, Sahil S; Kehr, Andrew D; Rule, Gordon S; Jen-Jacobson, Linda

    2016-11-08

    Metal ion cofactors can alter the energetics and specificity of sequence specific protein-DNA interactions, but it is unknown if the underlying effects on structure and dynamics are local or dispersed throughout the protein-DNA complex. This work uses EcoRV endonuclease as a model, and catalytically inactive lanthanide ions, which replace the Mg 2+ cofactor. Nuclear magnetic resonance (NMR) titrations indicate that four Lu 3+ or two La 3+ cations bind, and two new crystal structures confirm that Lu 3+ binding is confined to the active sites. NMR spectra show that the metal-free EcoRV complex with cognate (GATATC) DNA is structurally distinct from the nonspecific complex, and that metal ion binding sites are not assembled in the nonspecific complex. NMR chemical shift perturbations were determined for 1 H- 15 N amide resonances, for 1 H- 13 C Ile-δ-CH 3 resonances, and for stereospecifically assigned Leu-δ-CH 3 and Val-γ-CH 3 resonances. Many chemical shifts throughout the cognate complex are unperturbed, so metal binding does not induce major conformational changes. However, some large perturbations of amide and side chain methyl resonances occur as far as 34 Å from the metal ions. Concerted changes in specific residues imply that local effects of metal binding are propagated via a β-sheet and an α-helix. Both amide and methyl resonance perturbations indicate changes in the interface between subunits of the EcoRV homodimer. Bound metal ions also affect amide hydrogen exchange rates for distant residues, including a distant subdomain that contacts DNA phosphates and promotes DNA bending, showing that metal ions in the active sites, which relieve electrostatic repulsion between protein and DNA, cause changes in slow dynamics throughout the complex.

  16. Metal Ion Binding at the Catalytic Site Induces Widely Distributed Changes in a Sequence Specific Protein–DNA Complex

    Science.gov (United States)

    2016-01-01

    Metal ion cofactors can alter the energetics and specificity of sequence specific protein–DNA interactions, but it is unknown if the underlying effects on structure and dynamics are local or dispersed throughout the protein–DNA complex. This work uses EcoRV endonuclease as a model, and catalytically inactive lanthanide ions, which replace the Mg2+ cofactor. Nuclear magnetic resonance (NMR) titrations indicate that four Lu3+ or two La3+ cations bind, and two new crystal structures confirm that Lu3+ binding is confined to the active sites. NMR spectra show that the metal-free EcoRV complex with cognate (GATATC) DNA is structurally distinct from the nonspecific complex, and that metal ion binding sites are not assembled in the nonspecific complex. NMR chemical shift perturbations were determined for 1H–15N amide resonances, for 1H–13C Ile-δ-CH3 resonances, and for stereospecifically assigned Leu-δ-CH3 and Val-γ-CH3 resonances. Many chemical shifts throughout the cognate complex are unperturbed, so metal binding does not induce major conformational changes. However, some large perturbations of amide and side chain methyl resonances occur as far as 34 Å from the metal ions. Concerted changes in specific residues imply that local effects of metal binding are propagated via a β-sheet and an α-helix. Both amide and methyl resonance perturbations indicate changes in the interface between subunits of the EcoRV homodimer. Bound metal ions also affect amide hydrogen exchange rates for distant residues, including a distant subdomain that contacts DNA phosphates and promotes DNA bending, showing that metal ions in the active sites, which relieve electrostatic repulsion between protein and DNA, cause changes in slow dynamics throughout the complex. PMID:27786446

  17. An Aqueous Metal-ion Capacitor with Oxidised Carbon Nanotubes and Metallic Zinc Electrodes

    Directory of Open Access Journals (Sweden)

    Yuheng Tian

    2016-10-01

    Full Text Available An aqueous metal ion capacitor comprising of a zinc anode, an oxidized carbon nanotubes (oCNTs cathode and a zinc sulfate electrolyte is reported. Since the shuttling cation is Zn2+, this typical metal ion capacitor is named as zinc-ion capacitor (ZIC. The ZIC integrates the divalent zinc stripping/plating chemistry with the surface-enabled pseudocapacitive cation adsorption/desorption on oCNTs. The surface chemistry and crystallographic structure of oCNTs were extensively characterized by combining X-ray photoelectron spectroscopy, Fourier-transformed infrared spectroscopy, Raman spectroscopy and X-ray powder diffraction. The function of the surface oxygen groups in surface cation storage was elucidated by a series of electrochemical measurement and the surface-enabled ZIC showed better performance than the ZIC with an un-oxidized CNT cathode. The reaction mechanism at the oCNT cathode involves the additional reversible Faradaic process, while the CNTs merely show electric double layer capacitive behavior involving a non-Faradaic process. The aqueous hybrid ZIC comprising the oCNT cathode exhibited a specific capacitance of 20 mF cm-2 (corresponding to 53 F g-1 in the range of 0-1.8 V at 10 mV s-1 and a stable cycling performance up to 5000 cycles.

  18. Release of metal ions from orthodontic appliances by in vitro studies: a systematic literature review.

    Science.gov (United States)

    Mikulewicz, Marcin; Chojnacka, Katarzyna

    2011-03-01

    In the present work, a systematic literature review on release of metal ions from orthodontic appliances under in vitro conditions is described. Detailed and schematic analysis of used materials and applied methods (immersion media, incubation time, temperature, and analytical techniques) is provided. The PubMed search identified 40 studies, among which eight met the selection criteria. One additional study was included in the review. All the authors agreed that the doses of released metal ions were far below the toxic level and the dietary intake. Although the concentrations of metal ions in immersion media greatly differed, the general conclusions were coherent. It must be underlined that the main disadvantage of in vitro tests was that the experimental setup did not reflect in vivo conditions, e.g., the presence of biofilm, which grows on the surface of the materials in oral cavity. The presence and activity of microflora to a large extent is responsible for the process of corrosion, in particular, biodeterioration. The further scheme of in vitro research should incorporate changeable conditions of oral cavity environment (pH, dynamic conditions-saliva flow) and the presence of microbiological flora (microbiological attack) in the experimental design and, first of all, the real proportions of appliance elements.

  19. The ion-electron correlation function in liquid metals

    International Nuclear Information System (INIS)

    Takeda, S.; Tamaki, S.; Waseda, Y.

    1985-01-01

    The structure factors of liquid Zn at 723 K, Sn at 523 K and Bi at 573 K have been determined by neutron diffraction with sufficient accuracy and compared with those of X-ray diffraction. A remarkable difference in the structural information between the two methods is clearly found around the first peak region as well as in the slightly varied peak positions, and it is apparently larger than the experimental errors. With these facts in mind, a new method evaluating the ion-electron correlation function in liquid metals has been proposed by using the measured structural data of X-rays and neutrons, with the help of theoretical values of the electron-electron correlation function by he Utsumi-Ichimaru scheme. This method has been applied to liquid Zn, Sn and Bi, and the radial distribution function of valence electrons around an ion has been estimated, from which the ionic radius and the schematic diagram of the electron distribution map are obtained. The ionic radii evaluated in this work have been found to agree well with those proposed by Pauling. (author)

  20. Alzheimer’s disease: How metal ions define β-amyloid function

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2017-01-01

    Alzheimer’s disease is increasingly recognized to be linked to the function and status of metal ions, and recently, the amyloid hypothesis has been strongly intertwined with the metal ion hypothesis; in fact, these two hypotheses fit well together and are not mutually contradictory. This review...

  1. Effect of pH, various divalent metal ion and different substrates on ...

    African Journals Online (AJOL)

    EZUGWU ARINZE LINUS

    Key words: Glucoamylase, pH, metal ions, Aspergillus niger, tiger nut starch, amylopectin. INTRODUCTION. Glucoamylase (α-1 ... glycosidic bonds from the non-reducing ends of starch and 1,6-alpha-glucsidic linkages in ..... stable at neutral pH 7.0, it is more likely to readily form neucleophilichydroxide ions with metals by ...

  2. Generic NICA-Donnan model parameters for metal-ion binding by humic substances

    NARCIS (Netherlands)

    Milne, C.J.; Kinniburgh, D.G.; Riemsdijk, van W.H.; Tipping, E.

    2003-01-01

    A total of 171 datasets of literature and experimental data for metal-ion binding by fulvic and humic acids have been digitized and re-analyzed using the NICA-Donnan model. Generic parameter values have been derived that can be used for modeling in the absence of specific metal-ion binding

  3. Measuring free metal ion concentrations in multicomponent solutions using Donnan Membrane Technique

    NARCIS (Netherlands)

    Kalis, E.J.J.; Temminghoff, E.J.M.; Weng, L.P.; Riemsdijk, van W.H.

    2007-01-01

    Among speciation techniques that are able to measure free metal ion concentrations, the Donnan membrane technique (DMT) has the advantage that it can measure many different free metal ion concentrations simultaneously in a multicomponent sample. Even though the DMT has been applied to several

  4. Development of an Electrochemical Metal-Ion Biosensor Using Self-Assembled Peptide Nanofibrils

    DEFF Research Database (Denmark)

    Viguier, Bruno; Zor, Kinga; Kasotakis, Emmanouil

    2011-01-01

    This article describes the combination of self-assembled peptide nanofibrils with metal electrodes for the development of an electrochemical metal-ion biosensor. The biological nanofibrils were immobilized on gold electrodes and used as biorecognition elements for the complexation with copper ion...

  5. New generation Amberlite XAD resin for the removal of metal ions: A review.

    Science.gov (United States)

    Ahmad, Akil; Siddique, Jamal Akhter; Laskar, Mohammad Asaduddin; Kumar, Rajeev; Mohd-Setapar, Siti Hamidah; Khatoon, Asma; Shiekh, Rayees Ahmad

    2015-05-01

    The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter's presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction, serves as the promising solution. The mechanism involved in solid phase extraction (SPE) depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area, durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced. Copyright © 2015. Published by Elsevier B.V.

  6. Solid-phase materials for chelating metal ions and methods of making and using same

    Science.gov (United States)

    Harrup, Mason K.; Wey, John E.; Peterson, Eric S.

    2003-06-10

    A solid material for recovering metal ions from aqueous streams, and methods of making and using the solid material, are disclosed. The solid material is made by covalently bonding a chelating agent to a silica-based solid, or in-situ condensing ceramic precursors along with the chelating agent to accomplish the covalent bonding. The chelating agent preferably comprises a oxime type chelating head, preferably a salicylaldoxime-type molecule, with an organic tail covalently bonded to the head. The hydrocarbon tail includes a carbon-carbon double bond, which is instrumental in the step of covalently bonding the tail to the silica-based solid or the in-situ condensation. The invented solid material may be contacted directly with aqueous streams containing metal ions, and is selective to ions such as copper (II) even in the presence of such ions as iron (III) and other materials that are present in earthen materials. The solid material with high selectivity to copper may be used to recover copper from mining and plating industry streams, to replace the costly and toxic solvent extraction steps of conventional copper processing.

  7. Metal Ions Removal Using Nano Oxide Pyrolox™ Material

    Science.gov (United States)

    Gładysz-Płaska, A.; Skwarek, E.; Budnyak, T. M.; Kołodyńska, D.

    2017-02-01

    The paper presents the use of Pyrolox™ containing manganese nano oxides used for the removal of Cu(II), Zn(II), Cd(II), and Pb(II) as well as U(VI) ions. Their concentrations were analyzed using the atomic absorption spectrometer SpectrAA 240 FS (Varian) as well as UV-vis method. For this purpose the static kinetic and equilibrium studies were carried out using the batch technique. The effect of solution pH, shaking time, initial metal ion concentrations, sorbent dosage, and temperature was investigated. The equilibrium data were analyzed using the sorption isotherm models proposed by Freundlich, Langmuir-Freundlich, Temkin, and Dubinin-Radushkevich. The kinetic results showed that the pseudo second order kinetic model was found to correlate the experimental data well. The results indicate that adsorption of Cu(II), Zn(II), Cd(II), and Pb(II) as well as U(VI) ions is strongly dependent on pH. The value of pH 4-7 was optimal adsorption. The time to reach the equilibrium was found to be 24 h, and after this time, the sorption percentage reached about 70%. Kinetics of Cu(II), Zn(II), Cd(II), Pb(II), and U(VI) adsorption on the adsorbent can be described by the pseudo second order rate equation. Nitrogen adsorption/desorption, infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements for adsorbent characterization were performed. Characteristic points of the double layer determined for the studied Pyrolox™ sample in 0.001 mol/dm3 NaCl solution are pHPZC = 4 and pHIEP < 2.

  8. Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

    Science.gov (United States)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

    Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

  9. OCV Hysteresis in Li-Ion Batteries including Two-Phase Transition Materials

    Directory of Open Access Journals (Sweden)

    Michael A. Roscher

    2011-01-01

    Full Text Available The relation between batteries' state of charge (SOC and open-circuit voltage (OCV is a specific feature of electrochemical energy storage devices. Especially NiMH batteries are well known to exhibit OCV hysteresis, and also several kinds of lithium-ion batteries show OCV hysteresis, which can be critical for reliable state estimation issues. Electrode potential hysteresis is known to result from thermodynamical entropic effects, mechanical stress, and microscopic distortions within the active electrode materials which perform a two-phase transition during lithium insertion/extraction. Hence, some Li-ion cells including two-phase transition active materials show pronounced hysteresis referring to their open-circuit voltage. This work points out how macroscopic effects, that is, diffusion limitations, superimpose the latte- mentioned microscopic mechanisms and lead to a shrinkage of OCV hysteresis, if cells are loaded with high current rates. To validate the mentioned interaction, Li-ion cells' state of charge is adjusted to 50% with various current rates, beginning from the fully charged and the discharged state, respectively. As a pronounced difference remains between the OCV after charge and discharge adjustment, obviously the hysteresis vanishes as the target SOC is adjusted with very high current rate.

  10. Metal ion-improved complexation countercurrent chromatography for enantioseparation of dihydroflavone enantiomers.

    Science.gov (United States)

    Han, Chao; Wang, Wenli; Xue, Guimin; Xu, Dingqiao; Zhu, Tianyu; Wang, Shanshan; Cai, Pei; Luo, Jianguang; Kong, Lingyi

    2018-01-12

    Cu(II) ion was selected as an additive to improve the enantioseparation efficiency of three dihydroflavone enantiomers in high-speed counter-current chromatography (HSCCC), using hydroxypropyl-β-cyclodextrin (HP-β-CyD) as the chiral selector. The influences of important parameters, including the metal ion, the concentrations of HP-β-CyD and the Cu(II) ion, and the sample size were investigated. Under optimal conditions, three dihydroflavone enantiomers, including (±)-hesperetin, (±)-naringenin, and (±)-farrerol, were successfully enantioseparated. The chiral recognition mechanism was investigated. The enantioseparation was attributed to the different thermodynamic stabilities of the binary complexes of HP-β-CyD and (±)-hesperetin, and Cu(II) ion could enhance this difference by forming ternary complexes with the binary complexes. This Cu(II) ion-improved complexation HSCCC system exhibited improved performance for chiral separation, and therefore it has great application potential in the preparative enantioseparation of other compounds with similar skeletons. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya

    2015-01-01

    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu 2+ , Fe 2+ , Ni 2+ and Zn 2+ in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu 2+ , Fe 2+ and Ni 2+ caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe 2+ , Cu 2+ , Ni 2+ and Zn 2+ . • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions

  12. The sorption of metal ions on nanoscale zero-valent iron

    OpenAIRE

    Suponik Tomasz; Popczyk Marcin; Pierzyna Piotr

    2017-01-01

    The injection of the colloidal suspensions of nano-iron (nZVI) into an aquifer is a novel method of removing metal ions from acidic water. In the batch tests, the equilibrium study of the sorption of metal ions, Cu(II) and Zn(II), on Green Tea nanoscale Zero-Valent Ion (GT-nZVI) was carried out. The sorption of metal ions on this reactive material was described using the Langmuir, Freundlich and Sips models. This last model described in a better way the sorption equilibrium in the tested rang...

  13. Interaction of lactic acid bacteria with metal ions: opportunities for improving food safety and quality.

    Science.gov (United States)

    Mrvčić, Jasna; Stanzer, Damir; Solić, Ema; Stehlik-Tomas, Vesna

    2012-09-01

    Certain species of lactic acid bacteria (LAB), as well as other microorganisms, can bind metal ions to their cells surface or transport and store them inside the cell. Due to this fact, over the past few years interactions of metal ions with LAB have been intensively investigated in order to develop the usage of these bacteria in new biotechnology processes in addition to their health and probiotic aspects. Preliminary studies in model aqueous solutions yielded LAB with high absorption potential for toxic and essential metal ions, which can be used for improving food safety and quality. This paper provides an overview of results obtained by LAB application in toxic metal ions removing from drinking water, food and human body, as well as production of functional foods and nutraceutics. The biosorption abilities of LAB towards metal ions are emphasized. The binding mechanisms, as well as the parameters influencing the passive and active uptake are analyzed.

  14. NMR Structures and Dynamics in a Prohead RNA Loop that Binds Metal Ions.

    Science.gov (United States)

    Gu, Xiaobo; Park, Sun-Young; Tonelli, Marco; Cornilescu, Gabriel; Xia, Tianbing; Zhong, Dongping; Schroeder, Susan J

    2016-10-06

    Metal ions are critical for RNA structure and enzymatic activity. We present the structure of an asymmetric RNA loop that binds metal ions and has an essential function in a bacteriophage packaging motor. Prohead RNA is a noncoding RNA that is required for genome packaging activity in phi29-like bacteriophage. The loops in GA1 and phi29 bacteriophage share a conserved adenine that forms a base triple, although the structural context for the base triple differs. NMR relaxation studies and femtosecond time-resolved fluorescence spectroscopy reveal the dynamic behavior of the loop in the metal ion bound and unbound forms. The mechanism of metal ion binding appears to be an induced conformational change between two dynamic ensembles rather than a conformational capture mechanism. These results provide experimental benchmarks for computational models of RNA-metal ion interactions.

  15. An artificial tongue fluorescent sensor array for identification and quantitation of various heavy metal ions.

    Science.gov (United States)

    Xu, Wang; Ren, Changliang; Teoh, Chai Lean; Peng, Juanjuan; Gadre, Shubhankar Haribhau; Rhee, Hyun-Woo; Lee, Chi-Lik Ken; Chang, Young-Tae

    2014-09-02

    Herein, a small-molecule fluorescent sensor array for rapid identification of seven heavy metal ions was designed and synthesized, with its sensing mechanism mimicking that of a tongue. The photoinduced electron transfer and intramolecular charge transfer mechanism result in combinatorial interactions between sensor array and heavy metal ions, which lead to diversified fluorescence wavelength shifts and emission intensity changes. Upon principle component analysis (PCA), this result renders clear identification of each heavy metal ion on a 3D spatial dispersion graph. Further exploration provides a concentration-dependent pattern, allowing both qualitative and quantitative measurements of heavy metal ions. On the basis of this information, a "safe-zone" concept was proposed, which provides rapid exclusion of versatile hazardous species from clean water samples based on toxicity characteristic leaching procedure standards. This type of small-molecule fluorescent sensor array could open a new avenue for multiple heavy metal ion detection and simplified water quality analysis.

  16. Electrochemical Metal Ion Sensors. Exploiting Amino Acids and Peptides as Recognition Elements

    Directory of Open Access Journals (Sweden)

    Wenrong Yang

    2001-08-01

    Full Text Available Amino acids and peptides are known to bind metal ions, in some cases very strongly. There are only a few examples of exploiting this binding in sensors. The review covers the current literature on the interaction of peptides and metals and the electrochemistry of bound metal ions. Peptides may be covalently attached to surfaces. Of particular interest is the attachment to gold via sulfur linkages. Sulfur-containing peptides (eg cysteine may be adsorbed directly, while any amino group can be covalently attached to a carboxylic acid-terminated thiol. Once at a surface, the possibility for using the attached peptide as a sensor for metal ions becomes realised. Results from the authors’ laboratory and elsewhere have shown the potential for selective monitoring of metal ions at ppt levels. Examples of the use of poly-aspartic acid and the copper binding peptide Gly-Gly-His for detecting copper ions are given.

  17. Multiheteromacrocycles that Complex Metal Ions. Sixth Progress Report, 1 May 1979-30 April 1980

    Science.gov (United States)

    Cram, D. J.

    1980-01-15

    Objective is to design synthesize, and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes, and their clusters. Host organic compounds consist of strategically placed solvating, coordinating, and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions or by metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; number of binding sites; character of binding sites; and valences. During this period, hemispherands based on an aryloxy or cyclic urea unit, spherands based on aryloxyl units only, and their complexes with alkali metals and alkaline earths were investigated. An attempt to separate {sup 6}Li and {sup 7}Li by gel permeation chromatography of lithiospherium chloride failed. (DLC)

  18. Correlations of acute toxicity of metal ions and the covalent/ionic character of their bonds

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-01-01

    We have investigated correlations between physicochemical properties of 24 metal ions and their acute toxicity in mice and Drosophila. A high correlation for a softness parameter suggests that the relative covalent/ionic character of the bonds formed by the metal ions may be important in determining their toxicity. This hypothesis is reinforced by model calculations of metal binding to dinucleotides in water. Since the nature of bonds depends on ligand electronegativity, we searched for correlations involving this parameter. Although electronegativity is useful for interpreting some aspects of metal-ion behavior related to toxicity, it does not yield improved correlations. 8 refs., 3 figs., 1 tab.

  19. Divalent metal ion removal from aqueous solution by acid-treated ...

    African Journals Online (AJOL)

    ions determined from the Langmuir isotherm showed that C. indica had the largest sorption capacity for Pb2+ ions and the least sorption for Ni2+. The results also showed that garlic-treatment of C. indica biomass enhanced its sorption capacity for the divalent metal ions, with the enhancement factor varying from 1.22 to 1.44 ...

  20. Current Compensation of Hydrogen Ion Beam Extracted from PIG with Metal-Hydride Cathode

    International Nuclear Information System (INIS)

    Borisko, V.N.; Sereda, I.N.; Klochko, E.V.; Tseluyko, A.F.; Afanas'eva, I.A.

    2006-01-01

    The effect of extracted hydrogen ion beam compensation from reflective discharge with metal-hydride cathode that sufficiently widens the possible field of applying plasma sources of such type is found. The evolution of energy distribution function of ions extracted along the axial direction from reflective discharge with metal-hydride cathode depending on external parameters of the discharge is investigated. The electron distribution functions which compensate hydrogen ion beam are determined

  1. Label-free histamine detection with nanofluidic diodes through metal ion displacement mechanism

    OpenAIRE

    Ali, Mubarak; Ramirez Hoyos, Patricio; Duznovic, Ivana; Nasir, Saima; Mafe, Salvador; Ensinger, Wolfgang

    2017-01-01

    [EN] We design and characterize a nanofluidic device for the label-free specific detection of histamine neurotransmitter based on a metal ion displacement mechanism. The sensor consists of an asymmetric polymer nanopore fabricated via ion track-etching technique. The nanopore sensor surface having metal-nitrilotriacetic (NTA-Ni2+) chelates is obtained by covalent coupling of native carboxylic acid groups with N-alpha,N-alpha-bis(carboxymethyl)-L-lysine (BCML), followed by exposure to Ni2+ ion...

  2. Importance of diffuse metal ion binding to RNA.

    Science.gov (United States)

    Tan, Zhi-Jie; Chen, Shi-Jie

    2011-01-01

    RNAs are highly charged polyanionic molecules. RNA structure and function are strongly correlated with the ionic condition of the solution. The primary focus of this article is on the role of diffusive ions in RNA folding. Due to the long-range nature of electrostatic interactions, the diffuse ions can contribute significantly to RNA structural stability and folding kinetics. We present an overview of the experimental findings as well as the theoretical developments on the diffuse ion effects in RNA folding. This review places heavy emphasis on the effect of magnesium ions. Magnesium ions play a highly efficient role in stabilizing RNA tertiary structures and promoting tertiary structural folding. The highly efficient role goes beyond the mean-field effect such as the ionic strength. In addition to the effects of specific ion binding and ion dehydration, ion-ion correlation for the diffuse ions can contribute to the efficient role of the multivalent ions such as the magnesium ions in RNA folding.

  3. A Speciation Study on the Perturbing Effects of Iron Chelators on the Homeostasis of Essential Metal Ions.

    Science.gov (United States)

    Crisponi, Guido; Nurchi, Valeria Marina; Crespo-Alonso, Miriam; Sanna, Gavino; Zoroddu, Maria Antonietta; Alberti, Giancarla; Biesuz, Raffaela

    2015-01-01

    A number of reports have appeared in literature calling attention to the depletion of essential metal ions during chelation therapy on β-thalassaemia patients. We present a speciation study to determine how the iron chelators used in therapy interfere with the homeostatic equilibria of essential metal ions. This work includes a thorough analysis of the pharmacokinetic properties of the chelating agents currently in clinical use, of the amounts of iron, copper and zinc available in plasma for chelation, and of all the implied complex formation constants. The results of the study show that a significant amount of essential metal ions is complexed whenever the chelating agent concentration exceeds the amount necessary to coordinate all disposable iron--a frequently occurring situation during chelation therapy. On the contrary, copper and zinc do not interfere with iron chelation, except for a possible influence of copper on iron speciation during deferiprone treatment.

  4. Experimental studies of ion flow near the sheath edge in multiple ion species plasma including argon, xenon and neon

    Science.gov (United States)

    Severn, Greg; Yip, Chi-Shung; Hershkowitz, Noah; Baalrud, Scott D.

    2017-05-01

    The Bohm sheath criterion was studied with laser-induced fluorescence (LIF) in three ion species plasmas using two tunable diode lasers. It was found in the first LIF studies of three ion species plasma (Yip et al 2016 Phys. Plasmas 23 050703) in which krypton was added to a mixture of argon and xenon plasma confined in a multidipole, dc hot filament discharge, that the addition of krypton served to turn off instability enhanced collisional friction (IEF) found in two ion species plasma (Yip et al 2010 Phys. Plasmas). In this study, neon, a less massive atomic gas than argon was added. Argon and xenon ion velocity distribution functions (IVDFs) were measured at the sheath-presheath boundary near a negatively biased boundary plate, and the Ne+ density was systematically increased. We found in both cases that once the added ion density significantly exceeded the density of the other two ions, IVDF measurements consistent with the absence of the instability were obtained, and the measured ion sheath edge speeds tended toward their individual Bohm velocities. For all other relative concentrations, the ions reached the sheath edge neither at their Bohm speeds nor the ion sound speed of the system, consistent, qualitatively, with the action of the IEF.

  5. Preferential solvation, ion pairing, and dynamics of concentrated aqueous solutions of divalent metal nitrate salts

    Science.gov (United States)

    Yadav, Sushma; Chandra, Amalendu

    2017-12-01

    We have investigated the characteristics of preferential solvation of ions, structure of solvation shells, ion pairing, and dynamics of aqueous solutions of divalent alkaline-earth metal nitrate salts at varying concentration by means of molecular dynamics simulations. Hydration shell structures and the extent of preferential solvation of the metal and nitrate ions in the solutions are investigated through calculations of radial distribution functions, tetrahedral ordering, and also spatial distribution functions. The Mg2+ ions are found to form solvent separated ion-pairs while the Ca2+ and Sr2+ ions form contact ion pairs with the nitrate ions. These findings are further corroborated by excess coordination numbers calculated through Kirkwood-Buff G factors for different ion-ion and ion-water pairs. The ion-pairing propensity is found to be in the order of Mg(NO3) 2 ions which is achieved in the current study through electronic continuum correction force fields. A detailed analysis of the effects of ion-pairs on the structure and dynamics of water around the hydrated ions is done through classification of water into different subspecies based on their locations around the cations or anions only or bridged between them. We have looked at the diffusion coefficients, relaxation of orientational correlation functions, and also the residence times of different subspecies of water to explore the dynamics of water in different structural environments in the solutions. The current results show that the water molecules are incorporated into fairly well-structured hydration shells of the ions, thus decreasing the single-particle diffusivities and increasing the orientational relaxation times of water with an increase in salt concentration. The different structural motifs also lead to the presence of substantial dynamical heterogeneity in these solutions of strongly interacting ions. The current study helps us to understand the molecular details of hydration structure, ion

  6. Measurement of Cadmium Ion in the Presence of Metal-Binding Biopolymers in Aqueous Sample

    Directory of Open Access Journals (Sweden)

    Jian Pu

    2013-01-01

    Full Text Available In aqueous environment, water-soluble polymers are effectively used to separate free metal ions from metal-polymer complexes. The feasibilities of four different analytical techniques, cadmium ion-selective electrode, dialysis sack, chelate disk cartridge, and ultrafiltration, in distinguishing biopolymer-bound and nonbound cadmium in aqueous samples were investigated. And two different biopolymers were used, including bovine serum albumin (BSA and biopolymer solution extracted from cultivated activated sludge (ASBP. The ISE method requires relatively large amount of sample and contaminates sample during the pretreatment. After the long reaction time of dialysis, the equilibrium of cadmium in the dialysis sack would be shifted. Due to the sample nature, chelate disk cartridge could not filter within recommended time, which makes it unavailable for biopolymer use. Ultrafiltration method would not experience the difficulties mentioned above. Ultrafiltration method measuring both weakly and strongly bound cadmium was included in nominally biopolymer-cadmium complex. It had significant correlation with the Ion-selective electrode (ISE method (R2=0.989 for BSA, 0.985 for ASBP.

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

    Science.gov (United States)

    Masood, Farhana; Malik, Abdul

    2011-01-01

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

  8. Selective retention of basic compounds by metal aquo-ion affinity chromatography.

    Science.gov (United States)

    Asakawa, Yoshiki; Yamamoto, Eiichi; Asakawa, Naoki

    2014-10-01

    A novel metal aquo-ion affinity chromatography has been developed for the analysis of basic compounds using heat-treated silica gel containing hydrated metal cations (metal aquo-ions) as the packing material. The packing materials of the metal aquo-ion affinity chromatography were prepared by the immobilization of a single metal component such as Fe(III), Al(III), Ag(I), and Ni(II) on silica gel followed by extensive heat treatment. The immobilized metals form aquo-ions to present cation-exchange ability for basic analytes and the cation-exchange ability for basic analytes depends on pKa of the immobilized metal species. In the present study, to evaluate the retention characteristics of metal aquo-ion affinity chromatography, the on-line solid-phase extraction of drugs was investigated. Obtained data clearly evidence the selective retention capability of metal aquo-ion affinity chromatography for basic analytes with sufficient capacity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Method of fabricating electrodes including high-capacity, binder-free anodes for lithium-ion batteries

    Science.gov (United States)

    Ban, Chunmei; Wu, Zhuangchun; Dillon, Anne C.

    2017-01-10

    An electrode (110) is provided that may be used in an electrochemical device (100) such as an energy storage/discharge device, e.g., a lithium-ion battery, or an electrochromic device, e.g., a smart window. Hydrothermal techniques and vacuum filtration methods were applied to fabricate the electrode (110). The electrode (110) includes an active portion (140) that is made up of electrochemically active nanoparticles, with one embodiment utilizing 3d-transition metal oxides to provide the electrochemical capacity of the electrode (110). The active material (140) may include other electrochemical materials, such as silicon, tin, lithium manganese oxide, and lithium iron phosphate. The electrode (110) also includes a matrix or net (170) of electrically conductive nanomaterial that acts to connect and/or bind the active nanoparticles (140) such that no binder material is required in the electrode (110), which allows more active materials (140) to be included to improve energy density and other desirable characteristics of the electrode. The matrix material (170) may take the form of carbon nanotubes, such as single-wall, double-wall, and/or multi-wall nanotubes, and be provided as about 2 to 30 percent weight of the electrode (110) with the rest being the active material (140).

  10. Physical interaction and functional coupling between ACDP4 and the intracellular ion chaperone COX11, an implication of the role of ACDP4 in essential metal ion transport and homeostasis

    Directory of Open Access Journals (Sweden)

    Gu Jianguo

    2005-04-01

    Full Text Available Abstract Divalent metal ions such as copper, manganese, and cobalt are essential for cell development, differentiation, function and survival. These essential metal ions are delivered into intracellular domains as cofactors for enzymes involved in neuropeptide and neurotransmitter synthesis, superoxide metabolism, and other biological functions in a target specific fashion. Altering the homeostasis of these essential metal ions is known to connect to a number of human diseases including Alzheimer disease, amyotrophic lateral sclerosis, and pain. It remains unclear how these essential metal ions are delivered to intracellular targets in mammalian cells. Here we report that rat spinal cord dorsal horn neurons express ACDP4, a member of Ancient Conserved Domain Protein family. By screening a pretransformed human fetal brain cDNA library in a yeast two-hybrid system, we have identified that ACDP4 specifically interacts with COX11, an intracellular metal ion chaperone. Ectopic expression of ACDP4 in HEK293 cells resulted in enhanced toxicity to metal ions including copper, manganese, and cobalt. The metal ion toxicity became more pronounced when ACDP4 and COX11 were co-expressed ectopically in HEK293 cells, suggesting a functional coupling between them. Our results indicate a role of ACDP4 in metal ion homeostasis and toxicity. This is the first report revealing a functional aspect of this ancient conserved domain protein family. We propose that ACDP is a family of transporter protein or chaperone proteins for delivering essential metal ions in different mammalian tissues. The expression of ACDP4 on spinal cord dorsal horn neurons may have implications in sensory neuron functions under physiological and pathological conditions.

  11. Role of carboxylate ion and metal oxidation state on the morphology ...

    Indian Academy of Sciences (India)

    These precursors are an excellent source for the synthesis of metal and metal oxide nanoparticles. Cubes of (edge length ∼ 150 nm) Fe3O4 and elongated particles of Fe2O3 (∼ diameter of 200 nm) were obtained. The role of oxidation state of the metal ion in controlling the morphology of the nanostructured dicarboxylates ...

  12. Validation of ion chromatography for the determination of transition metal ions along with alkali, alkaline earth metal elements for uranium oxide fuel

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Prakash, Amrit; Afzal, Mohd.; Panakkal, J.P.

    2009-02-01

    The present report describes the use of Ion chromatography (IC) methods with spectrophotometric and direct conductivity detection for the determination of transition metal elements and alkali alkaline earth metal ions in UO 2 pellets. Transmet analytical column and Metrosep- cation 1-2 column were used for the separation of transition metal elements and alkali and alkaline earth metal elements respectively. Oxalic acid and mixture of pyridine 2,6-dicarboxylic acid (PDCA), Na 2 SO 4 and NaCl were used as mobile phase for the separation of transition metal ions and monitored after post - column reaction with 4,2-pyridylazo resorcinol (PAR) at 520nm spectrophotometrically. In the determination of alkali and alkaline earth metal ions the interference of transition metals are removed by complexing them with PDCA. Mixture of tartaric acid and PDCA employed in the separation of alkali and alkaline earth metal ions and monitored on direct conductivity detector. Mobile phase composition was optimised for the base line separation. Calibration plots of Fe 3+ , Cu 2+ , Ni 2+ , Co 2+ , Cd 2+ , Mn 2+ , Li + , Na + , K + , Mg 2+ , Ca 2+ and Sr 2+ were linear over a wide dynamic range with regression coefficient better than 0.999. Detection limit of above ions were between 5-30ppb. To prevent the overloading of the cation exchange column, uranium matrix was removed from UO 2 sample by solvent extraction with 30% TBP - TOPO/CCl 4 . Ten sintered UO2 pellets of same lot were analysed and R.S.D. ±10% was obtained. These methods were validated by analysis of ILCE standards of UO 2 . (author)

  13. Synthesis, Characterizations, and Applications of Metal-Ions Incorporated High Quality MCM-41 Catalysts

    International Nuclear Information System (INIS)

    Lim, Steven S.; Haller, Gary L.

    2013-01-01

    Various metal ions (transition and base metals) incorporated MCM-41 catalysts can be synthesized using colloidal and soluble silica with non-sodium involved process. Transition metal ion-typically V 5+ , Co 2+ , and Ni 2+ -incorporated MCM-41 catalysts were synthesized by isomorphous substitution of Si ions in the framework. Each incorporated metal ion created a single species in the silica framework, single-site solid catalyst, showing a substantial stability in reduction and catalytic activity. Radius of pore curvature effect was investigated with Co-MCM-41 by temperature programmed reduction (TPR). The size of metallic Co clusters, sub-nanometer, could be controlled by a proper reduction treatment of Co-MCM-41 having different pore size and the initial pH adjustment of the Co-MCM-41 synthesis solution. These small metallic clusters showed a high stability under a harsh reaction condition without serious migration, resulting from a direct anchoring of small metallic clusters to the partially or unreduced metal ions on the surface. After a complete reduction, partial occlusion of the metallic cluster surface by amorphous silica stabilized the particles against aggregations. As a probe reaction of particle size sensitivity, carbon single wall nanotubes (SWNT) were synthesized using Co-MCM-41. A metallic cluster stability test was performed by CO methanation using Co- and Ni-MCM-41. Methanol and methane partial oxidations were carried out with V-MCM-41, and the radius of pore curvature effect on the catalytic activity was investigated

  14. The Interchangeability of Plasma and Whole Blood Metal Ion Measurement in the Monitoring of Metal on Metal Hips

    Directory of Open Access Journals (Sweden)

    Ibrahim A. Malek

    2015-01-01

    Full Text Available One hundred and twenty six paired samples of plasma and whole blood were measured with inductively coupled plasma mass spectrometry technique for metal ions analysis to determine a relationship between them. There was a significant difference between the mean plasma and whole blood concentrations of both cobalt (Co and chromium (Cr (p<0.0001 for both Co and Cr. The mean ratio between plasma and whole blood Cr and Co was 1.56 (range: 0.39–3.85 and 1.54 (range: 0.64–18.26, respectively, but Bland and Altman analysis illustrated that this relationship was not universal throughout the range of concentrations. There was higher variability at high concentrations for both ions. We conclude that both these concentrations should not be used interchangeably and conversion factors are unreliable due to concentration dependent variability.

  15. Binding of monovalent alkali metal ions with negatively charged phospholipid membranes.

    Science.gov (United States)

    Maity, Pabitra; Saha, Baishakhi; Kumar, Gopinatha Suresh; Karmakar, Sanat

    2016-04-01

    We have systematically investigated the effect of various alkali metal ions with negatively charged phospholipid membranes. Size distributions of large unilamellar vesicles have been confirmed using dynamic light scattering. Zeta potential and effective charges per vesicle in the presence of various alkali metal ions have been estimated from the measured electrophoretic mobility. We have determined the intrinsic binding constant from the zeta potential using electrostatic double layer theory. The reasonable and consistent value of the intrinsic binding constant of Na(+), found at moderate NaCl concentration (10-100 mM), indicates that the Gouy-Chapman theory cannot be applied for very high (> 100mM) and very low (concentrations. The isothermal titration calorimetry study has revealed that the net binding heat of interaction of the negatively charged vesicles with monovalent alkali metal ions is small and comparable to those obtained from neutral phosphatidylcholine vesicles. The overall endothermic response of binding heat suggests that interaction is primarily entropy driven. The entropy gain might arise due to the release of water molecules from the hydration layer vicinity of the membranes. Therefore, the partition model which does not include the electrostatic contribution suffices to describe the interaction. The binding constant of Na(+) (2.4 ± 0.1 M(-1)), obtained from the ITC, is in agreement with that estimated from the zeta potential (-2.0 M(-1)) at moderate salt concentrations. Our results suggest that hydration dynamics may play a vital role in the membrane solution interface which strongly affects the ion-membrane interaction. Copyright © 2016 Elsevier B.V. All rights reserved

  16. A new strategy to stabilize oxytocin in aqueous solutions : I. The effects of divalent metal ions and citrate buffer

    NARCIS (Netherlands)

    Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J. M.; Hinrichs, Wouter L. J.; Frijlink, Henderik W.

    In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na+and K+) and divalent metal ions (Ca2+, Mg2+, and Zn2+) were tested all as chloride salts. The

  17. Water purification from metal ions using carbon nanoparticle-conjugated polymer nanocomposites.

    Science.gov (United States)

    Khaydarov, Rashid A; Khaydarov, Renat R; Gapurova, Olga

    2010-03-01

    The paper deals with a novel method of obtaining nanocarbon-conjugated polymer nanocomposites (NCPC) using nanocarbon colloids (NCC) and polyethylenimine (PEI) for water purification from metal ions. Size of NCC, process of NCPC synthesis, its chemical characteristics, ratio of NCC and PEI in NCPC, speed of coagulation of NCPC, mechanism of interaction of metal ions with NCPC, ability of removing metal ions from water by NCPC against pH have been studied. NCPC has a bonding capacity of 4.0-5.7mmol/g at pH 6 for most of the divalent metal ions. Percent of sorption of Zn(2+), Cd(2+), Cu(2+), Hg(2+), Ni(2+), Cr(6+) ions is higher than 99%. Lifetime of NCPC before coagulation in the treated water is 1s-1000min and depends on the ratio of polymeric molecules and carbon nanoparticle concentrations. Results of laboratory tests of the method are described. Copyright 2009 Elsevier Ltd. All rights reserved.

  18. Multiheteromacrocycles that complex metal ions. Third progress report, 1 May 1976--30 April 1977

    International Nuclear Information System (INIS)

    Cram, D.J.

    1977-01-01

    The overall objective of this research is to design, synthesize and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes and clusters. Host organic compounds consist of strategically placed solvating, coordinating and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions, or metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; numbers of binding sites; characters of binding sites; and valences. The specific compounds synthesized and their complexing and lipophilizing properties are summarized

  19. The Interchangeability of Plasma and Whole Blood Metal Ion Measurement in the Monitoring of Metal on Metal Hips

    OpenAIRE

    Malek, Ibrahim A.; Rogers, Joanne; King, Amanda Christina; Clutton, Juliet; Winson, Daniel; John, Alun

    2015-01-01

    One hundred and twenty six paired samples of plasma and whole blood were measured with inductively coupled plasma mass spectrometry technique for metal ions analysis to determine a relationship between them. There was a significant difference between the mean plasma and whole blood concentrations of both cobalt (Co) and chromium (Cr) (p < 0.0001 for both Co and Cr). The mean ratio between plasma and whole blood Cr and Co was 1.56 (range: 0.39?3.85) and 1.54 (range: 0.64?18.26), respectively, ...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Spectroscopy of metal-ion complexes with peptide-related ligands.

    Science.gov (United States)

    Dunbar, Robert C

    2015-01-01

    With new experimental tools and techniques developing rapidly, spectroscopic approaches to characterizing gas-phase metal ion complexes have emerged as a lively area of current research, with particular emphasis on structural and conformational information. The present review gives detailed attention to the metal-ion complexes of amino acids (and simple derivatives), much of whose study has focused on the question of charge-solvation vs salt-bridge modes of complexation. Alkali metal ions have been most frequently examined, but work with other metal ions is discussed to the extent to which they have been studied. The majority of work has been with simple cationic metal ion complexes, while recent excursions into deprotonated complexes, anionic complexes, and dimer complexes are also of interest. Interest is growing in complexes of small peptides, which are discussed both in the context of possible zwitterion formation as a charge-solvation alternative, and of the alternative metal-ion bond formation to amide nitrogens in structures involving iminol tautomerization. The small amount of work on complexes of large peptides and proteins is considered, as are the structural consequences of solvation of the gas-phase complexes. Spectroscopy in the visible/UV wavelength region has seen less attention than the IR region for structure determination of gas-phase metal-ion complexes; the state of this field is briefly reviewed.

  2. Virulence modulation of Candida albicans biofilms by metal ions commonly released from orthodontic devices.

    Science.gov (United States)

    Ronsani, Maiara Medeiros; Mores Rymovicz, Alinne Ulbrich; Meira, Thiago Martins; Trindade Grégio, Ana Maria; Guariza Filho, Odilon; Tanaka, Orlando Motohiro; Ribeiro Rosa, Edvaldo Antonio

    2011-12-01

    The installation of metal devices leads to an increase in the salivary concentration of metal ions and in the growth of salivary Candida spp. However, the relationship between released metal ions and Candida virulence has not been previously examined. The objective of this study was to evaluate whether metal ions affect fungal virulence. We prepared culture media containing Ni(2+), Fe(3+), Cr(3+), Co(2+) or a mixture of these metal ions at concentrations similar to those released in saliva of orthodontic patients. Biofilms of Candida albicans SC5314 were grown for 72 h and their biomasses were determined. The supernatants were analyzed for secretory aspartyl protease (SAP) and hemolysin activities. To verify changes in virulence following treatment with metals, proteolytic and hemolytic activities were converted into specific activities. The results revealed that all ions, except Co(2+), caused increases in biofilm biomass. In addition, Ni(2+) caused an increase in SAP activity and Fe(3+) reduced hemolytic activity. However, the SAP and hemolysin activities in the presence of the mixture of ions did not differ from those of control. These results indicate that metal ions released during the degradation of orthodontic appliances can modulate virulence factors in C. albicans biofilms. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Interaction of metal ions and DNA films on gold surfaces: an electrochemical impedance study.

    Science.gov (United States)

    Bin, Xiaomin; Kraatz, Heinz-Bernhard

    2009-07-01

    Electrochemical impedance spectroscopy (EIS) has been used to investigate the effects of a number of metal ions with DNA films on gold surfaces exploiting [Fe(CN)6](3-/4-) as a solution-based redox probe. Alkaline earth metal ions Mg2+, Ca2+, trivalent Al3+, La3+ and divalent transition metal ions Ni2+, Cu2+, Cd2+ and Hg2+ have been selected in this study and the results are compared with previous studies on the effects of Zn2+ on the EIS of DNA films. All experimental results were evaluated with the help of equivalent circuits which allowed the extraction of resistive and capacitive components. For all metal ions studied here, addition of the metal ions causes a decrease in the charge transfer resistance. The difference of charge transfer resistance (DeltaR(ct)) of ds-DNA films in the presence and absence of the various metal ions is different and particular to any given metal ion. In addition, we studied the EIS of ds-DNA films containing a single A-C mismatch in the presence and absence of Ca2+, Zn2+, Cd2+ and Hg2+. DeltaR(ct) values for ds-DNA films with a single A-C mismatch is smaller than those of fully matched ds-DNA films.

  4. Peptides having antimicrobial activity and their complexes with transition metal ions.

    Science.gov (United States)

    Jeżowska-Bojczuk, Małgorzata; Stokowa-Sołtys, Kamila

    2018-01-01

    Peptide antibiotics are produced by bacterial, mammalian, insect or plant organisms in defense against invasive microbial pathogens. Therefore, they are gaining importance as anti-infective agents. There are a number of antibiotics that require metal ions to function properly. Metal ions play a key role in their action and are involved in specific interactions with proteins, nucleic acids and other biomolecules. On the other hand, it is well known that some antimicrobial agents possess functional groups that enable them interacting with metal ions present in physiological fluids. Some findings support a hypothesis that they may alter the serum metal ions concentration in humans. Complexes usually have a higher positive charge than uncomplexed compounds. This means that they might interact more tightly with polyanionic DNA and RNA molecules. It has been shown that several metal ion complexes with antibiotics promote degradation of DNA. Some of them, such as bleomycin, form stable complexes with redox metal ions and split the nucleic acids chain via the free radicals mechanism. However, this is not a rule. For example blasticidin does not cause DNA damage. This indicates that some peptide antibiotics can be considered as ligands that effectively lower the oxidative activity of transition metal ions. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  5. Application of Sargassum biomass to remove heavy metal ions from synthetic multi-metal solutions and urban storm water runoff.

    Science.gov (United States)

    Vijayaraghavan, K; Teo, Ting Ting; Balasubramanian, R; Joshi, Umid Man

    2009-05-30

    The ability of Sargassum sp. to biosorb four metal ions, namely lead, copper, zinc, and manganese from a synthetic multi-solute system and real storm water runoff has been investigated for the first time. Experiments on synthetic multi-solute systems revealed that Sargassum performed well in the biosorption of all four metal ions, with preference towards Pb, followed by Cu, Zn, and Mn. The solution pH strongly affected the metal biosorption, with pH 6 being identified as the optimal condition for achieving maximum biosorption. Experiments at different biosorbent dosages revealed that good biosorption capacity as well as high metal removal efficiency was observed at 3g/L. The biosorption kinetics was found to be fast with equilibrium being attained within 50 min. According to the Langmuir isotherm model, Sargassum exhibited maximum uptakes of 214, 67.5, 24.2 and 20.2mg/g for lead, copper, zinc, and manganese, respectively in single-solute systems. In multi-metal systems, strong competition between four metal ions in terms of occupancy binding sites was observed, and Sargassum showed preference in the order of Pb>Cu>Zn>Mn. The application of Sargassum to remove four heavy metal ions in real storm water runoff revealed that the biomass was capable of removing the heavy metal ions. However, the biosorption performance was slightly lower compared to that of synthetic metal solutions. Several factors were responsible for this difference, and the most important factor is the presence of other contaminants such as anions, organics, and other trace metals in the runoff.

  6. Three-dimensional metallic micro/nanostructures fabricated by two-photon-induced reduction of metal ions

    Science.gov (United States)

    Tanaka, Takuo; Ishikawa, Atsushi; Kawata, Satoshi

    2006-08-01

    We report on a technique that enables to fabricate three-dimensional (3D) metallic microstructures by means of two photon- induced metal-ion reduction. A femtosecond near-infrared laser is focused by a high-NA objective lens into a metal-ion aqueous solution. Due to the nonlinear nature of the two-photon absorption (TPA) process, metal-ions are directly reduced only at the focused spot. By scanning the laser beam spot in three dimensions, we can directly obtain arbitrary 3D metallic structures. To fabricate silver and gold structures, we use a 0.2-M aqueous solution of silver nitrate (AgNO 3) and a 0.24-M aqueous solution of tetra chloroauric acid (HAuCl 4), respectively. We demonstrate the fabrication of a continuous and electrically conductive silver wire whose minimum width is 400 nm. Electrical measurement shows that the resistivity of the fabricated silver wire is 5.30 × 10 -8 Ωm, which is only 3.3 times larger than that of bulk silver (1.62 × 10 -8 Ωm). We also discuss the resolution of our technique in terms of ions diffusion based on the Fick's first law and the mobility of metal-ions in aqueous solution. Moreover, the realization of a selfstanding 3D silver microstructures on the substrates are demonstrated. This method will become a promising technique for fabricating 3D plasmonic micro/nano structures with arbitrary shape.

  7. Formation of biaxial texture in metal films by selective ion beam etching

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.J. [Department of Materials Science and Engineering, University of Florida, 106 Rhines Hall, P.O. Box 116400, Gainesville, FL 32611 (United States); Norton, D.P. [Department of Materials Science and Engineering, University of Florida, 106 Rhines Hall, P.O. Box 116400, Gainesville, FL 32611 (United States)]. E-mail: dnort@mse.ufl.edu; Selvamanickam, Venkat [IGC-SuperPower, LLC, 450 Duane Avenue, Schenectady, NY 12304 (United States)

    2006-05-15

    The formation of in-plane texture via ion bombardment of uniaxially textured metal films was investigated. In particular, selective grain Ar ion beam etching of uniaxially textured (0 0 1) Ni was used to achieve in-plane aligned Ni grains. Unlike conventional ion beam assisted deposition, the ion beam irradiates the uniaxially textured film surface with no impinging deposition flux. The initial uniaxial texture is established via surface energy minimization with no ion irradiation. Within this sequential texturing method, in-plane grain alignment is driven by selective etching and grain overgrowth. Biaxial texture was achieved for ion beam irradiation at elevated temperature.

  8. Formation of biaxial texture in metal films by selective ion beam etching

    International Nuclear Information System (INIS)

    Park, S.J.; Norton, D.P.; Selvamanickam, Venkat

    2006-01-01

    The formation of in-plane texture via ion bombardment of uniaxially textured metal films was investigated. In particular, selective grain Ar ion beam etching of uniaxially textured (0 0 1) Ni was used to achieve in-plane aligned Ni grains. Unlike conventional ion beam assisted deposition, the ion beam irradiates the uniaxially textured film surface with no impinging deposition flux. The initial uniaxial texture is established via surface energy minimization with no ion irradiation. Within this sequential texturing method, in-plane grain alignment is driven by selective etching and grain overgrowth. Biaxial texture was achieved for ion beam irradiation at elevated temperature

  9. Metal ion complex formation in small lakes of the Western Siberian Arctic zone

    Science.gov (United States)

    Kremleva, Tatiana; Dinu, Marina

    2017-04-01

    The paper is based on joint investigation of the Tyumen State University (Russia, Tyumen) and the Geochemistry and Analytical Chemistry Vernadsky Institute of Russian Academy of Sciences (Moscow, Russia) during 2012-2014 period. It presents the results of research of chemical composition of about 70 small lakes located in the area of tundra and northern taiga of West Siberia (Russia, Yamal-Nenets and Khanty-Mansi Autonomous Districts of the Tyumen region). The investigation includes determination of different parameters of natural water samples: • content of trace elements (Al, Fe, Mn, Cr, Cu, Ni, Zn, Cd, Co, Pb, etc., total more than 60 elements) by emission method with an inductively coupled plasma (ICP-MS) using mass spektrometrometre Element 2 equipment; • content of inorganic and total carbon (TIC and TC) by elemental analysis and the difference between the total and inorganic carbon gives the organic carbon content (TOC); • pH value by potentiometric method; • content of basic ions (Na+, Ca2+, K+, Mg2+, NH4+, Cl-, SO42-, NO3-, PO43-) by ion chromatography. Determination of the chemical composition of samples was conducted in the accredited laboratory according to standard procedures with regular quality control of results. Heavy metals in natural waters can exist in various forms: free (hydrated) ions bound in complexes with organic or inorganic ligands, as well as in the form of suspensions. The form of metal existence has a significant influence on their availability to transport in aquatic organisms. Metal ions associated in stable complexes with organic substances are considered less toxic. From the previous investigations state that the most stable complexes are ligands with organic ions Fe3+, Al3+. The main conclusion of the present research states that if the total content of aluminum, iron and manganese ions (meq/dm3) is equal to or greater than the concentration of dissolved organic carbon (TOC, mg/dm3) in lakes water other heavy metals will

  10. Modified polypropylene fabrics and their metal ion sorption role in aqueous solution

    Science.gov (United States)

    Ehrhardt, A.; Miyazaki, K.; Sato, Y.; Hori, T.

    2005-11-01

    Polypropylene non-woven fabrics were grafted with glycidyl methacrylate by the electron beam irradiation method and the introduced epoxide rings were chemically conversed to hydroxyl and thiol groups. The modified polypropylene fabrics showed sufficient hydrophilicity to adsorb the metal ions from the aqueous solutions. The modified fibers were examined as adsorbents for metal ions dissolved in seawater and its model solutions at various conditions. The amount of ions adsorbed on the fabrics was determined by a sequential plasma spectrometry. The modified polypropylene fabrics adsorbed extremely high amount of Au(III) and Hg(II) ions. The equilibrium adsorption of Au(III) was almost not disturbed, even if Cu(II), Cd(II), Pb(II) and the other ions coexisted in the same aqueous solution. Nowadays, the most widely advantages of this technique are the recovery of metal ions dissolved in water and the treatment of industrial wastewater systems.

  11. Modified polypropylene fabrics and their metal ion sorption role in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ehrhardt, A. [University of Fukui, Graduate School of Engineering, Bunkyo 3-9-1, Fukui City, Fukui 910-8507 (Japan)]. E-mail: anelise@acbio2.acbio.fukui-u.ac.jp; Miyazaki, K. [Industrial and Technical Center of Fukui Prefecture (Japan); Sato, Y. [Mitsuya Corporation Ltd. (Japan); Hori, T. [University of Fukui, Graduate School of Engineering, Bunkyo 3-9-1, Fukui City, Fukui 910-8507 (Japan)

    2005-11-15

    Polypropylene non-woven fabrics were grafted with glycidyl methacrylate by the electron beam irradiation method and the introduced epoxide rings were chemically conversed to hydroxyl and thiol groups. The modified polypropylene fabrics showed sufficient hydrophilicity to adsorb the metal ions from the aqueous solutions. The modified fibers were examined as adsorbents for metal ions dissolved in seawater and its model solutions at various conditions. The amount of ions adsorbed on the fabrics was determined by a sequential plasma spectrometry. The modified polypropylene fabrics adsorbed extremely high amount of Au(III) and Hg(II) ions. The equilibrium adsorption of Au(III) was almost not disturbed, even if Cu(II), Cd(II), Pb(II) and the other ions coexisted in the same aqueous solution. Nowadays, the most widely advantages of this technique are the recovery of metal ions dissolved in water and the treatment of industrial wastewater systems.

  12. Sensing of heavy metal ions by intrinsic TMV coat protein fluorescence

    Science.gov (United States)

    Bayram, Serene S.; Green, Philippe; Blum, Amy Szuchmacher

    2018-04-01

    We propose the use of a cysteine mutant of TMV coat protein as a signal transducer for the selective sensing and quantification of the heavy metal ions, Cd2+, Pb2+, Zn2+ and Ni2+ based on intrinsic tryptophan quenching. TMV coat protein is inexpensive, can be mass-produced since it is expressed and extracted from E-coli. It also displays several different functional groups, enabling a wide repertoire of bioconjugation chemistries; thus it can be easily integrated into functional devices. In addition, TMV-ion interactions have been widely reported and utilized for metallization to generate organic-inorganic hybrid composite novel materials. Building on these previous observations, we herein determine, for the first time, the TMV-ion binding constants assuming the static fluorescence quenching model. We also show that by comparing TMV-ion interactions between native and denatured coat protein, we can distinguish between chemically similar heavy metal ions such as cadmium and zinc ions.

  13. Linear dose dependence of ion beam mixing of metals on Si

    International Nuclear Information System (INIS)

    Poker, D.B.; Appleton, B.R.

    1985-01-01

    These experiments were conducted to determine the dose dependences of ion beam mixing of various metal-silicon couples. V/Si and Cr/Si were included because these couples were previously suspected of exhibiting a linear dose dependence. Pd/Si was chosen because it had been reported as exhibiting only the square root dependence. Samples were cut from wafers of (100) n-type Si. The samples were cleaned in organic solvents, etched in hydrofluoric acid, and rinsed with methanol before mounting in an oil-free vacuum system for thin-film deposition. Films of Au, V, Cr, or Pd were evaporated onto the Si samples with a nominal deposition rate of 10 A/s. The thicknesses were large compared with those usually used to measure ion beam mixing and were used to ensure that conditions of unlimited supply were met. Samples were mixed with Si ions ranging in energy from 300 to 375 keV, chosen to produce ion ranges that significantly exceeded the metal film depth. Si was used as the mixing ion to prevent impurity doping of the Si substrate and to exclude a background signal from the Rutherford backscattering (RBS) spectra. Samples were mixed at room temperature, with the exception of the Au/Si samples, which were mixed at liquid nitrogen temperature. The samples were alternately mixed and analyzed in situ without exposure to atmosphere between mixing doses. The compositional distributions after mixing were measured using RBS of 2.5-MeV 4 He atoms

  14. Structures and energetics of complexation of metal ions with ammonia, water, and benzene: A computational study.

    Science.gov (United States)

    Sharma, Bhaskar; Neela, Y Indra; Narahari Sastry, G

    2016-04-30

    Quantum chemical calculations have been performed at CCSD(T)/def2-TZVP level to investigate the strength and nature of interactions of ammonia (NH3 ), water (H2 O), and benzene (C6 H6 ) with various metal ions and validated with the available experimental results. For all the considered metal ions, a preference for C6 H6 is observed for dicationic ions whereas the monocationic ions prefer to bind with NH3 . Density Functional Theory-Symmetry Adapted Perturbation Theory (DFT-SAPT) analysis has been employed at PBE0AC/def2-TZVP level on these complexes (closed shell), to understand the various energy terms contributing to binding energy (BE). The DFT-SAPT result shows that for the metal ion complexes with H2 O electrostatic component is the major contributor to the BE whereas, for C6 H6 complexes polarization component is dominant, except in the case of alkali metal ion complexes. However, in case of NH3 complexes, electrostatic component is dominant for s-block metal ions, whereas, for the d and p-block metal ion complexes both electrostatic and polarization components are important. The geometry (M(+) -N and M(+) -O distance for NH3 and H2 O complexes respectively, and cation-π distance for C6 H6 complexes) for the alkali and alkaline earth metal ion complexes increases down the group. Natural population analysis performed on NH3 , H2 O, and C6 H6 complexes shows that the charge transfer to metal ions is higher in case of C6 H6 complexes. © 2015 Wiley Periodicals, Inc.

  15. Characterization of Metal Ion ­ Colloid Interaction: Impact On Colloid-facilitated Transport

    Science.gov (United States)

    Specht, C. H.; Schmitt, D.; Kaulisch, E.-M.; Frimmel, F. H.

    It is generally accepted, that metal transport in natural aquatic systems strongly de- pends on the metal binding form. Besides complex formation with well defined inor- ganic and organic ligands, the interaction with colloidal particles and soil material is one of the most important reactions of metal ions in aquatic systems. Mobile colloids compete with the stationary soil matrix for binding of metal ions and might facili- tate their transport. Important representatives for mineral and organic colloids are clay minerals and natural organic matter (NOM), respectively. In this work, the interaction of metal ions with clay minerals and NOM is characterized by coupling of asymmetric flow field-flow fractionation AF4 to inductively coupled plasma ­ mass spectrometry (ICPMS). A method for separating mineral from organic colloids is presented, which allows to quantify the amount of metals being bound to either colloid. For different metal ions (Cu, Zn, Pb, Pt) and a metalloid (As) a different extent of binding to either colloid was found.The information obtained from the AF4-ICPMS measurements was useful for the understanding of the observations from column experiments which were conducted to quantify the colloid-facilitated metal transport. In column experiments, the transport of the mineral colloids itself and the influence of NOM onto the colloid transport were investigated. Furthermore, the dependance of colloid transport from the ionic strength and the pH value was elucidated. In order to get information about the co-transport of metal ions by organic and mineral colloids, metal ions were adsorbed onto the colloidal material and a distribution coef- ficient of the metal ions between the colloidal phase and the solution was determined. The colloidal suspension containing both, "free" and adsorbed metal ions were then injected onto the column. The direct metal breakthrough caused by colloidal trans- port was detected at the column outlet. The results clearly

  16. Development of sensitive holographic devices for physiological metal ion detection

    Science.gov (United States)

    Sabad-e.-Gul; Martin, Suzanne; Cassidy, John; Naydenova, Izabela

    2017-08-01

    The development of selective alkali metal ions sensors in particular is a subject of significant interest. In this respect, the level of blood electrolytes, particularly H+, Na+, K+ and Cl- , is widely used to monitor aberrant physiologies associated with pulmonary emphysema, acute and chronic renal failure, heart failure, diabetes. The sensors reported in this paper are created by holographic recording of surface relief structures in a self-processing photopolymer material. The structures are functionalized by ionophores dibenzo-18-crown-6 (DC) and tetraethyl 4-tert-butylcalix[4]arene (TBC) in plasticised polyvinyl chloride (PVC) matrix. Interrogation of these structures by light allows indirect measurements of chemical analytes' concentration in real time. We present results on the optimisation and testing of the holographic sensor. A self-processing acrylamide-based photopolymer was used to fabricate the required photonic structures. The performance of the sensors for detection of K+ and Na+ was investigated. It was observed that the functionalisation with DC provides a selective response of the devices to K+ over Na+ and TBC coated surface structures are selectively sensitive to Na+. The sensor responds to Na+ within the physiological ranges. Normal levels of Na+ and K+ in human serum lie within the ranges 135-148mM and 3.5-5.3 mM respectively.

  17. MCTBI: a web server for predicting metal ion effects in RNA structures.

    Science.gov (United States)

    Sun, Li-Zhen; Zhang, Jing-Xiang; Chen, Shi-Jie

    2017-08-01

    Metal ions play critical roles in RNA structure and function. However, web servers and software packages for predicting ion effects in RNA structures are notably scarce. Furthermore, the existing web servers and software packages mainly neglect ion correlation and fluctuation effects, which are potentially important for RNAs. We here report a new web server, the MCTBI server (http://rna.physics.missouri.edu/MCTBI), for the prediction of ion effects for RNA structures. This server is based on the recently developed MCTBI, a model that can account for ion correlation and fluctuation effects for nucleic acid structures and can provide improved predictions for the effects of metal ions, especially for multivalent ions such as Mg 2+ effects, as shown by extensive theory-experiment test results. The MCTBI web server predicts metal ion binding fractions, the most probable bound ion distribution, the electrostatic free energy of the system, and the free energy components. The results provide mechanistic insights into the role of metal ions in RNA structure formation and folding stability, which is important for understanding RNA functions and the rational design of RNA structures. © 2017 Sun et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  18. Hybrid (Vlasov-Fluid) simulation of ion-acoustic solitons chain formation including trapped electrons

    Energy Technology Data Exchange (ETDEWEB)

    Behjat, E.; Aminmansoor, F.; Abbasi, H. [Faculty of Energy Engineering and Physics, Amirkabir University of Technology, P. O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2015-08-15

    Disintegration of a Gaussian profile into ion-acoustic solitons in the presence of trapped electrons [H. Hakimi Pajouh and H. Abbasi, Phys. Plasmas 15, 082105 (2008)] is revisited. Through a hybrid (Vlasov-Fluid) model, the restrictions associated with the simple modified Korteweg de-Vries (mKdV) model are studied. For instance, the lack of vital information in the phase space associated with the evolution of electron velocity distribution, the perturbative nature of mKdV model which limits it to the weak nonlinear cases, and the special spatio-temporal scaling based on which the mKdV is derived. Remarkable differences between the results of the two models lead us to conclude that the mKdV model can only monitor the general aspects of the dynamics, and the precise picture including the correct spatio-temporal scales and the properties of solitons should be studied within the framework of hybrid model.

  19. Physiological and toxicological changes in the skin resulting from the action and interaction of metal ions.

    Science.gov (United States)

    Lansdown, A B

    1995-01-01

    The human environment contains more than 50 metal or metalloid elements. At least 15 are recognized as trace elements, with zinc, calcium, copper, magnesium, and iron having specific roles in skin morphogenesis and function. The present review focuses on the presumed role of metal ions in the skin, their competition for carrier proteins, and membrane receptors. Evidence presented shows that the balance of trace metal ions is critical for normal skin and repair mechanisms following injury. Xenobiotic ions can impair this balance, leading to pathological change. The skin acts as an organ of elimination of excess trace metals and xenobiotic ions from the body, but mechanisms of voidance vary for different metals. Metal ions are an important cause of allergies, and evidence is presented to show that the majority of metals or metal compounds can induce allergic changes. Except for chromium and nickel, which are among the most common human allergens, animal models have provided little information. At least cadmium, thorium, lead, chromium, nickel, beryllium, and arsenic and proven or putative carcinogens in animals or humans on the basis of cytological or epidemiological evidence. However, only arsenic exhibits a clear predilection for the skin. Other metals such as gold can induce subcutaneous sarcoma following injection, but the relevance of this observation in terms of human occupational risk is discounted.

  20. Leaching of Metal Ions from Blast Furnace Slag by Using Aqua Regia for CO2 Mineralization

    OpenAIRE

    Jun-Hwan Bang; Seung-Woo Lee; Chiwan Jeon; Sangwon Park; Kyungsun Song; Whan Joo Jo; Soochun Chae

    2016-01-01

    Blast furnace slag (BFS) was selected as the source of Ca for CO2 mineralization purposes to store CO2 as CaCO3. BFS was dissolved using aqua regia (AR) for leaching metal ions for CO2 mineralization and rejecting metal ions that were not useful to obtain pure CaCO3 (as confirmed by XRD analysis). The AR concentration, as well as the weight of BFS in an AR solution, was varied. Increasing the AR concentration resulted in increased metal ion leaching efficiencies. An optimum concentration of 2...

  1. Benchmarking a computational design method for the incorporation of metal ion-binding sites at symmetric protein interfaces.

    Science.gov (United States)

    Hansen, William A; Khare, Sagar D

    2017-08-01

    The design of novel metal-ion binding sites along symmetric axes in protein oligomers could provide new avenues for metalloenzyme design, construction of protein-based nanomaterials and novel ion transport systems. Here, we describe a computational design method, symmetric protein recursive ion-cofactor sampling (SyPRIS), for locating constellations of backbone positions within oligomeric protein structures that are capable of supporting desired symmetrically coordinated metal ion(s) chelated by sidechains (chelant model). Using SyPRIS on a curated benchmark set of protein structures with symmetric metal binding sites, we found high recovery of native metal coordinating rotamers: in 65 of the 67 (97.0%) cases, native rotamers featured in the best scoring model while in the remaining cases native rotamers were found within the top three scoring models. In a second test, chelant models were crossmatched against protein structures with identical cyclic symmetry. In addition to recovering all native placements, 10.4% (8939/86013) of the non-native placements, had acceptable geometric compatibility scores. Discrimination between native and non-native metal site placements was further enhanced upon constrained energy minimization using the Rosetta energy function. Upon sequence design of the surrounding first-shell residues, we found further stabilization of native placements and a small but significant (1.7%) number of non-native placement-based sites with favorable Rosetta energies, indicating their designability in existing protein interfaces. The generality of the SyPRIS approach allows design of novel symmetric metal sites including with non-natural amino acid sidechains, and should enable the predictive incorporation of a variety of metal-containing cofactors at symmetric protein interfaces. © 2017 The Protein Society.

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

    Science.gov (United States)

    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.

  3. Polymer monoliths with chelating functionalities for solid phase extraction of metal ions from water.

    Science.gov (United States)

    Wang, Hongxia; Zhang, Haiyang; Lv, Yongqin; Svec, Frantisek; Tan, Tianwei

    2014-05-23

    Simple devices for the adsorption and preconcentration of metal ions comprising various monolithic polymers have been prepared by in situ polymerization within the 5.5cm long and 5.6mm i.d. polypropylene syringes. Poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was modified with ethylenediamine to obtain the chelating material. The poly(butyl methacrylate-co-ethylene dimethacrylate) and poly(lauryl methacrylate-co-ethylene dimethacrylate) monoliths were first photografted with glycidyl methacrylate prior to functionalization with ethylenediamine. Alternatively, other chelating functionalities including poly(ethylene imines) varying in molecular weight and shape (linear and branched) as well as lysozyme were also attached to the monolithic supports. We found that the poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith functionalized with ethylenediamine exhibited the best chelating properties characterized with rapid adsorption and a capacity of 111.2mg/g (537μmol/g) for Pb(2+), 38.1mg/g (649μmol/g) for Ni(2+), 69.9mg/g (1100μmol/g) for Cu(2+), and 188.9mg/g (3633μmol/g) for Cr(3+). The very fast desorption was then achieved using 1.0mol/L HNO3 as the eluent. An enrichment factor of 300 was observed for metal ions adsorbed from solutions containing 2ppb of the metal. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. MOM Failure Modes: An In-Depth Look at Metal Ions and Implant Wear

    Directory of Open Access Journals (Sweden)

    Tom Donaldson, MD

    2014-03-01

    Full Text Available Contemporary MOM bearings (large-diameter heads offered the perceived benefits of much greater range of motion and greater stability with reduced risk of impingement and dislocation. A variety of design and Both positive [1-3] and negative reports [4-8] have now emerged with regard to total hip arthroplasty (THA and resurfacing arthroplasty. As a result, there has been an avalanche of studies focused on critical issues such as: surgical positioning, shallow cups (face angles 144-170° [9-11] and “edge loading”. [5,7,12-17] However, there are several, possibly synergistic, risk scenarios that could trigger adverse MOM wear and very little progress has been made in understanding such interacting parameters. In an effort to understand the role of metal ion analysis and how it relates to revision surgery and implant wear, selected MOM revised cases were reviewed [28]. Retrieval data was included in conjunction with metal ion analyses and intraoperative observations to determine various failure modes.  We suggest MOM devices that are well fixed but fail after 2 years can be classified into one of six modes: (i normal, (ii allergic reaction, (iii 3rd body wear, (iv repetitive subluxation with metal impingement, (v multi-directional subluxation with soft tissue impingement, and (vi repetitive subluxation with soft tissue impingement.

  5. The deposition of thin metal films at the high-intensity pulsed-ion-beam influence on the metals

    International Nuclear Information System (INIS)

    Remnev, G.E.; Zakoutaev, A.N.; Grushin, I.I.; Matvenko, V.M.; Potemkin, A.V.; Ryzhkov, V.A.; Chernikov, E.V.

    1996-01-01

    A high-intensity pulsed ion beam with parameters: ion energy 350-500 keV, ion current density at a target > 200 A/cm 2 , pulse duration 60 ns, was used for metal deposition. The film deposition rate was 0.6-4.0 mm/s. Transmission electron microscopy/transmission electron diffraction investigations of the copper target-film system were performed. The impurity content in the film was determined by x-ray fluorescence analysis and secondary ion mass spectrometry. The angular distributions of the ablated plasma were measured. (author). 2 figs., 7 refs

  6. Heavy metal ion extraction of crownether compounds with supercritical CO2 fluid

    International Nuclear Information System (INIS)

    Yun, Y. H.; Ko, M. S.; Kim, H. W.; Park, K. H.; Kim, H. D.

    2001-01-01

    Benzocrownether-diarylethene derivatives (5BCD, 6BCD) were synthesized and utilized to extract metal ions into supercritical CO 2 . In order to enhance the CO 2 -phillicity and the extraction capability, synthesized compounds have both perfluoro unit and benzocrown moiety and were compared with dicyclohexano 18-crown-6(DC18C6). With minimal amount of water and counter ions such as perfluorooctanesulphonic acid or perfluorooctanic acid, their metal ion(Sr 2+ , Co +2 , Na + ) extraction efficiency was investigated. 5BCD, 6BCD showed more than 50% extraction for Sr +2 , Na + ions and their extraction efficiency was better than that of DC18C6 compound

  7. Nanodiamonds act as Trojan horse for intracellular delivery of metal ions to trigger cytotoxicity.

    Science.gov (United States)

    Zhu, Ying; Zhang, Yu; Shi, Guosheng; Yang, Jinrong; Zhang, Jichao; Li, Wenxin; Li, Aiguo; Tai, Renzhong; Fang, Haiping; Fan, Chunhai; Huang, Qing

    2015-02-05

    Nanomaterials hold great promise for applications in the delivery of various molecules with poor cell penetration, yet its potential for delivery of metal ions is rarely considered. Particularly, there is limited insight about the cytotoxicity triggered by nanoparticle-ion interactions. Oxidative stress is one of the major toxicological mechanisms for nanomaterials, and we propose that it may also contribute to nanoparticle-ion complexes induced cytotoxicity. To explore the potential of nanodiamonds (NDs) as vehicles for metal ion delivery, we used a broad range of experimental techniques that aimed at getting a comprehensive assessment of cell responses after exposure of NDs, metal ions, or ND-ion mixture: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Trypan blue exclusion text, optical microscope observation, synchrotron-based scanning transmission X-ray microscopy (STXM) and micro X-ray fluorescence (μXRF) microscopy, inductively coupled plasma-mass spectrometry (ICP-MS), reactive oxygen species (ROS) assay and transmission electron microscopy (TEM) observation. In addition, theoretical calculation and molecular dynamics (MD) computation were used to illustrate the adsorption properties of different metal ion on NDs as well as release profile of ion from ND-ion complexes at different pH values. The adsorption capacity of NDs for different metal ions was different, and the adsorption for Cu2+ was the most strong among divalent metal ions. These different ND-ion complexes then had different cytotoxicity by influencing the subsequent cellular responses. Detailed investigation of ND-Cu2+ interaction showed that the amount of released Cu2+ from ND-Cu2+ complexes at acidic lysosomal conditions was much higher than that at neutral conditions, leading to the elevation of intracellular ROS level, which triggered cytotoxicity. By theoretical approaches, we demonstrated that the functional carbon surface and cluster structures of NDs made them

  8. Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

    Directory of Open Access Journals (Sweden)

    Albrecht Hartmann

    Full Text Available INTRODUCTION: The use of metal-on-metal (MoM total hip arthroplasty (THA increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. OBJECTIVE: To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. METHODS: Systematic review of clinical trials (RCTs and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor, patient characteristics as well as study quality characteristics (secondary explanatory factors. RESULTS: Overall, 104 studies (11 RCTs, 93 epidemiological studies totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L. Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. DISCUSSION: Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed "time out" for stemmed large-head MoM-THA and recommend a restricted

  9. Metal Ion Concentrations in Body Fluids after Implantation of Hip Replacements with Metal-on-Metal Bearing – Systematic Review of Clinical and Epidemiological Studies

    Science.gov (United States)

    Hartmann, Albrecht; Hannemann, Franziska; Lützner, Jörg; Seidler, Andreas; Drexler, Hans; Günther, Klaus-Peter; Schmitt, Jochen

    2013-01-01

    Introduction The use of metal-on-metal (MoM) total hip arthroplasty (THA) increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds) in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. Objective To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. Methods Systematic review of clinical trials (RCTs) and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum) in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor), patient characteristics as well as study quality characteristics (secondary explanatory factors). Results Overall, 104 studies (11 RCTs, 93 epidemiological studies) totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine) irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L). Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. Discussion Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed „time out“ for stemmed large-head MoM-THA and recommend a restricted indication for hip

  10. Multiresponsive polysiloxane bearing spiropyran: synthesis and sensing of pH and metal ions of different valence

    Science.gov (United States)

    Li, Hongqi; Zheng, Tao; Zhao, Yong; Xu, Zhenxiang; Dai, Xuhang; Shao, Zhiyu

    2018-03-01

    A spiropyran-appended polysiloxane (SP-Si) was synthesized and characterized. The pH-responsive behavior of SP-Si was investigated. It was found that with the decrease of the pH of SP-Si solution the intensity of the absorption peak at 440 nm increased and the color of SP-Si solution turned from colorless to yellow gradually. The polymer serves as chemosensor for colorimetric detection of Ag+ and Fe3+ ions. Addition of Ag+ and Fe3+ ions to SP-Si solution induced color change from colorless to brown and earthy yellow, respectively. Sensing of Ag+ ions by SP-Si was not affected by common competitive metal ions except Hg2+ ions. Based on the transformation from colorless SP-Si solution with negligible absorption at 440 nm to brown SP-Si/Ag+ showing extremely strong absorption at 440 nm by addition of Ag+ ions and subsequent transformation from brown to colorless SP-Si/Ag+/Hg2+ with relatively weak absorption at 440 nm after addition of 1 equivalent of Hg2+ ions, SP-Si/Ag+ system serves as a dual colorimetric and spectroscopic probe for highly selective and sensitive detection of Hg2+ ions. The selective detection of Fe3+ ions by SP-Si is not interfered by common competitive metal ions including Na+, K+, Li+, Hg2+, Ni2+, Fe2+, Zn2+, Co2+, Sr2+, Cu2+, Al3+, Ce3+ and Cr3+. The detection limit of Ag+ and Fe3+ ions is 1.45 × 10‑6 M and 3.52 × 10‑6 M, respectively.

  11. Metal-on-metal hip resurfacing: correlation between clinical and radiological assessment, metal ions and ultrasound findings.

    Science.gov (United States)

    Scaglione, M; Fabbri, L; Bianchi, N; Dell'Omo, D; Guido, G

    2015-04-01

    We report the clinical, radiological and wear analysis of 52 consecutive MoM hip resurfacings (performed on 49 younger patients) to a mean follow-up of 9.2 years. Every patient underwent X-ray and clinical evaluation (HHS). Ultrasonography of the hip was performed in all patients in order to identify possible cystic or solid mass in periprosthetic tissue. In case of mass >20 mm, further MRI was performed to better analyse the characteristics of lesion. Five patients (five hips) had a revision. The overall survival rate was 90.38 %. The average HHS at follow-up examination was 95.5 points. No progressive radiolucent areas and no sclerosis or osteolysis around the implants were found. The US and RMI imaging showed a pseudotumour formation in two patients (correlated with high metal ion levels in blood and urine), both asymptomatic. A significant positive correlation between inclination of the acetabular component and serum metal ion levels was found (r = 0.64 and r = 0.62 for cobalt and chromium, respectively).

  12. Mechanism of the inhibition of milk xanthine oxidase activity by metal ions: a transient kinetic study.

    Science.gov (United States)

    Mondal, M S; Sau, A K; Mitra, S

    2000-07-14

    The nature and mechanism of the inhibition of the oxidoreductase activity of milk xanthine oxidase (XO) by Cu(2+), Hg(2+) and Ag(+) ions has been studied by steady state and stopped flow transient kinetic measurements. The results show that the nature of the inhibition is noncompetitive. The inhibition constants for Cu(2+) and Hg(2+) are in the micromolar and that for Ag(+) is in the nanomolar range. This suggests that the metal ions have strong affinity towards XO. pH dependence studies of the inhibition indicate that at least two ionisable groups of XO are involved in the binding of these metal ions. The effect of the interaction of the metal ions on the reductive and oxidative half reactions of XO has been investigated, and it is observed that the kinetic parameters of the reductive half reaction are not affected by these metal ions. However, the interaction of these metal ions with XO significantly affects the kinetic parameters of the oxidative half reaction. It is suggested that this may be the main cause for the inhibition of XO activity by the metal ions.

  13. Potassium salts of fatty acids as precipitating agents of alkaline earth metal ions

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Sin'kova, L.A.

    1977-01-01

    Regularities have been studied of precipitation of ions of alkaline-earth elements with caprilate, pelargonate, caprinate, undecanate, laurate, tridecanate, myristate, pentadecanate, palmitate, and stearate of potassium. It has been shown that completeness of precipitation of metal ions is determined by the nature of alkaline-earth metal and potassium salt as well as by pH value and temperature of the solution. The study of temperature dependence of soaps of alkaline-earth metals makes it possible to calculate the heats of dissolution of laurates of alkaline-earth metals, and a change in entropy and free energy

  14. A Simplified Model to Estimate the Concentration of Inorganic Ions and Heavy Metals in Rivers

    Directory of Open Access Journals (Sweden)

    Clemêncio Nhantumbo

    2016-10-01

    Full Text Available This paper presents a model that uses only pH, alkalinity, and temperature to estimate the concentrations of major ions in rivers (Na+, K+, Mg2+, Ca2+, HCO3−, SO42−, Cl−, and NO3− together with the equilibrium concentrations of minor ions and heavy metals (Fe3+, Mn2+, Cd2+, Cu2+, Al3+, Pb2+, and Zn2+. Mining operations have been increasing, which has led to changes in the pollution loads to receiving water systems, meanwhile most developing countries cannot afford water quality monitoring. A possible solution is to implement less resource-demanding monitoring programs, supported by mathematical models that minimize the required sampling and analysis, while still being able to detect water quality changes, thereby allowing implementation of measures to protect the water resources. The present model was developed using existing theories for: (i carbonate equilibrium; (ii total alkalinity; (iii statistics of major ions; (iv solubility of minerals; and (v conductivity of salts in water. The model includes two options to estimate the concentrations of major ions: (1 a generalized method, which employs standard values from a world-wide data base; and (2 a customized method, which requires specific baseline data for the river of interest. The model was tested using data from four monitoring stations in Swedish rivers with satisfactory results.

  15. Comparison of metal ion release from different bracket archwire combinations: an in vitro study.

    Science.gov (United States)

    Karnam, Srinivas Kumar; Reddy, A Naveen; Manjith, C M

    2012-05-01

    The metal ion released from the orthodontic appliance may cause allergic reactions particularly nickel and chromium ions. Hence, this study was undertaken to determine the amount of nickel, chromium, copper, cobalt and iron ions released from simulated orthodontic appliance made of new archwires and brackets. Sixty sets of new archwire, band material, brackets and ligature wires were prepared simulating fixed orthodontic appliance. These sets were divided into four groups of fifteen samples each. Group 1: Stainless steel rectangular archwires. Group 2: Rectangular NiTi archwires. Group 3: Rectangular copper NiTi archwires. Group 4: Rectangular elgiloy archwires. These appliances were immersed in 50 ml of artificial saliva solution and stored in polypropylene bottles in the incubator to simulate oral conditions. After 90 days the solution were tested for nickel, chromium, copper, cobalt and iron ions using atomic absorption spectrophotometer. Results showed that high levels of nickel ions were released from all four groups, compared to all other ions, followed by release of iron ion levels. There is no significant difference in the levels of all metal ions released in the different groups. The study confirms that the use of newer brackets and newer archwires confirms the negligible release of metal ions from the orthodontic appliance. The measurable amount of metals, released from orthodontic appliances in artificial saliva, was significantly below the average dietary intake and did not reach toxic concentrations.

  16. Requirement for transient metal ions revealed through computational analysis for DNA polymerase going in reverse

    Science.gov (United States)

    Perera, Lalith; Freudenthal, Bret D.; Beard, William A.; Shock, David D.; Pedersen, Lee G.; Wilson, Samuel H.

    2015-01-01

    DNA polymerases facilitate faithful insertion of nucleotides, a central reaction occurring during DNA replication and repair. DNA synthesis (forward reaction) is “balanced,” as dictated by the chemical equilibrium by the reverse reaction of pyrophosphorolysis. Two closely spaced divalent metal ions (catalytic and nucleotide-binding metals) provide the scaffold for these reactions. The catalytic metal lowers the pKa of O3′ of the growing primer terminus, and the nucleotide-binding metal facilitates substrate binding. Recent time-lapse crystallographic studies of DNA polymerases have identified an additional metal ion (product metal) associated with pyrophosphate formation, leading to the suggestion of its possible involvement in the reverse reaction. Here, we establish a rationale for a role of the product metal using quantum mechanical/molecular mechanical calculations of the reverse reaction in the confines of the DNA polymerase β active site. Additionally, site-directed mutagenesis identifies essential residues and metal-binding sites necessary for pyrophosphorolysis. The results indicate that the catalytic metal site must be occupied by a magnesium ion for pyrophosphorolysis to occur. Critically, the product metal site is occupied by a magnesium ion early in the pyrophosphorolysis reaction path but must be removed later. The proposed dynamic nature of the active site metal ions is consistent with crystallographic structures. The transition barrier for pyrophosphorolysis was estimated to be significantly higher than that for the forward reaction, consistent with kinetic activity measurements of the respective reactions. These observations provide a framework to understand how ions and active site changes could modulate the internal chemical equilibrium of a reaction that is central to genome stability. PMID:26351676

  17. A computational study of adsorption of divalent metal ions on graphene oxide

    Directory of Open Access Journals (Sweden)

    Somphob Thompho

    2017-12-01

    Full Text Available Adsorption of divalent metal ions (Pb2+,Cd2+, Zn2+,Cu2+ on graphene oxide (GO was studied using density functional theory (DFT. Adsorption geometries and energies, as well as the nature of the binding energy, were calculated for the interaction of divalent metal ions with oxygen-containing groups on the surface of GO. The configurations of the complexes were modeled by placing the divalent metal ions above the center and perpendicular to the surface. Binding of Cu2+ to the GO sheet was predicted to be much stronger than that for other divalent metal ions. Calculated results show good agreement with experimental observations and provide useful information for environmental pollution cleanup.

  18. Photodetachment of negative ion in a gradient electric field near a metal surface

    International Nuclear Information System (INIS)

    Liu Tian-Qi; Wang De-Hua; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng

    2012-01-01

    Based on closed-orbit theory, the photodetachment of H − in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H − near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. (atomic and molecular physics)

  19. Determination of heavy metal ions in vegetable samples using a magnetic metal-organic framework nanocomposite sorbent.

    Science.gov (United States)

    Hassanpour, Akbar; Hosseinzadeh-Khanmiri, Rahim; Babazadeh, Mirzaagha; Abolhasani, Jafar; Ghorbani-Kalhor, Ebrahim

    2015-01-01

    This paper describes the synthesis and application of a novel magnetic metal-organic framework (MOF) [(Fe₃O₄-benzoyl isothiocyanate)/Cu₃(benzene-1,3,5-tricarboxylate)₂] to pre-concentrate trace amounts of Cd(II), Pb(II), Zn(II) and Cr(III) ions and their determination by flame atomic absorption spectrometry. A Box-Behnken design was used to find the parameters affecting the pre-concentration procedure through response surface methodology. Three factors including uptake time, amount of the magnetic sorbent and pH of the sample were selected as affecting factors in the sorption step, and four factors including type, volume and concentration of the eluent as well as the elution time were selected in the elution step for the optimisation study. The opted values were 30 mg, 10.1 min, 5.9, EDTA, 4.0 ml, 0.57 mol l(-1) EDTA solution and 13.0 min for the amount of the magnetic sorbent, uptake time, pH of the sample, type, volume, concentration of the eluent, and elution time, respectively. The limits of detection (LODs) were 0.12, 0.7, 0.16, and 0.4 ng ml(-1) for Cd(II), Pb(II), Zn(II) and Cr(III) ions, respectively. The relative standard deviations (RSDs) of the method were less than 7.2% for five separate batch experiments for the determination of 30 μg l(-1) of Cd(II), Pb(II), Zn(II) and Cr(III) ions. The sorption capacity of the [(Fe₃O₄-benzoyl isothiocyanate)/MOF] was 175 mg g(-1) for Cd(II), 168 mg g(-1) for Pb(II), 210 mg g(-1) for Zn(II) and 196 mg g(-1) for Cr(III). It was found that the magnetic MOF nanocomposite demonstrated a higher capacity compared with Fe₃O₄-benzoyl isothiocyanate. Finally, the magnetic MOF nanocomposite was successfully applied to the rapid extraction of trace amounts of the heavy metal ions from vegetable samples.

  20. Adsorption of Cd(II) Metal Ion on Adsorbent beads from Biomass Saccharomycess cereviceae - Chitosan

    Science.gov (United States)

    Hasri; Mudasir

    2018-01-01

    The adsorbent beads that was preparation from Saccharomycess cereviceae culture strain FN CC 3012 and shrimp shells waste and its application for adsorption of Cd (II) metal ion has been studied. The study start with combination of Saccharomycess cereviceae biomass to chitosan (Sc-Chi), contact time, pH of solution and initial concentration of cations. Total Cd(II) metal ion adsorbed was calculated from the difference of metal ion concentration before and after adsorption by AAS. The results showed that optimum condition for adsorption of Cd(II) ions by Sc-Chi beads was achieved with solution pH of 4, contact time of 60 minutes and initial concentration adsorption 100mg/L. The hydroxyl (-OH) and amino (-NH2) functional groups were believed to be responsible for the adsorption of Cd(II) ions.

  1. Occurrence of metal ions in rice produced in Uruguay

    Directory of Open Access Journals (Sweden)

    Mario Rivero

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice under the concept "Rice is Life". The largest nutritional problems occurring globally are protein-energy malnutrition, Ca, Fe, I, Zn and vitamin A deficiencies. Being rice the staple food more consumed worldwide, outstanding care is taken on its composition levels.Uruguay has emerged as medium-size rice producer and Latin America's major rice exporter, and is now amongst the world's top ten. Thus, the knowledge of toxic as well as micronutrient elements is very important. Here is reported the determination in forty nine samples of rice (Oryza sativa L. of As, Cd, Cr, and Pb by ET AAS in samples digested by dry ashing, and Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni and Zn by FAAS and Hg by CV AAS using microwave-assisted decomposition.The amount of all the metal ions studied in this work fall within the range typical of rice around the world. All the rice samples tested showed lower levels of As, Cd, Hg and Pb than the maximum limit permitted by governmental and international organizations.Potassium was the most abundant mineral followed by Mg and Ca and amongst microelements the presence of Cu, Fe, Mo, Mn, Na and Zn was outstanding.The milling process highly affects the contents of K, Mg, Mn, Na and Zn while little influence has on Ca, Co, Cu and Fe concentrations.Unexpected loss of Ca, Fe and Mn during parboiling process was detected. 

  2. Theory Meets Experiment: Metal Ion Effects in HCV Genomic RNA Kissing Complex Formation.

    Science.gov (United States)

    Sun, Li-Zhen; Heng, Xiao; Chen, Shi-Jie

    2017-01-01

    The long-range base pairing between the 5BSL3. 2 and 3'X domains in hepatitis C virus (HCV) genomic RNA is essential for viral replication. Experimental evidence points to the critical role of metal ions, especially Mg 2+ ions, in the formation of the 5BSL3.2:3'X kissing complex. Furthermore, NMR studies suggested an important ion-dependent conformational switch in the kissing process. However, for a long time, mechanistic understanding of the ion effects for the process has been unclear. Recently, computational modeling based on the Vfold RNA folding model and the partial charge-based tightly bound ion (PCTBI) model, in combination with the NMR data, revealed novel physical insights into the role of metal ions in the 5BSL3.2-3'X system. The use of the PCTBI model, which accounts for the ion correlation and fluctuation, gives reliable predictions for the ion-dependent electrostatic free energy landscape and ion-induced population shift of the 5BSL3.2:3'X kissing complex. Furthermore, the predicted ion binding sites offer insights about how ion-RNA interactions shift the conformational equilibrium. The integrated theory-experiment study shows that Mg 2+ ions may be essential for HCV viral replication. Moreover, the observed Mg 2+ -dependent conformational equilibrium may be an adaptive property of the HCV genomic RNA such that the equilibrium is optimized to the intracellular Mg 2+ concentration in liver cells for efficient viral replication.

  3. Elements including metals in the atomizer and aerosol of disposable electronic cigarettes and electronic hookahs.

    Directory of Open Access Journals (Sweden)

    Monique Williams

    Full Text Available Our purpose was to quantify 36 inorganic chemical elements in aerosols from disposable electronic cigarettes (ECs and electronic hookahs (EHs, examine the effect of puffing topography on elements in aerosols, and identify the source of the elements.Thirty-six inorganic chemical elements and their concentrations in EC/EH aerosols were determined using inductively coupled plasma optical emission spectroscopy, and their source was identified by analyzing disassembled atomizers using scanning electron microscopy and energy dispersive X-ray spectroscopy.Of 36 elements screened, 35 were detected in EC/EH aerosols, while only 15 were detected in conventional tobacco smoke. Some elements/metals were present in significantly higher concentrations in EC/EH aerosol than in cigarette smoke. Concentrations of particular elements/metals within EC/EH brands were sometimes variable. Aerosols generated at low and high air-flow rates produced the same pattern of elements, although the total element concentration decreased at the higher air flow rate. The relative amount of elements in the first and last 60 puffs was generally different. Silicon was the dominant element in aerosols from all EC/EH brands and in cigarette smoke. The elements appeared to come from the filament (nickel, chromium, thick wire (copper coated with silver, brass clamp (copper, zinc, solder joints (tin, lead, and wick and sheath (silicon, oxygen, calcium, magnesium, aluminum. Lead was identified in the solder and aerosol of two brands of EHs (up to 0.165 μg/10 puffs.These data show that EC/EH aerosols contain a mixture of elements, including heavy metals, with concentrations often significantly higher than in conventional cigarette smoke. While the health effects of inhaling mixtures of heated metals is currently not known, these data will be valuable in future risk assessments involving EC/EH elements/metals.

  4. Elements including metals in the atomizer and aerosol of disposable electronic cigarettes and electronic hookahs.

    Science.gov (United States)

    Williams, Monique; Bozhilov, Krassimir; Ghai, Sanjay; Talbot, Prue

    2017-01-01

    Our purpose was to quantify 36 inorganic chemical elements in aerosols from disposable electronic cigarettes (ECs) and electronic hookahs (EHs), examine the effect of puffing topography on elements in aerosols, and identify the source of the elements. Thirty-six inorganic chemical elements and their concentrations in EC/EH aerosols were determined using inductively coupled plasma optical emission spectroscopy, and their source was identified by analyzing disassembled atomizers using scanning electron microscopy and energy dispersive X-ray spectroscopy. Of 36 elements screened, 35 were detected in EC/EH aerosols, while only 15 were detected in conventional tobacco smoke. Some elements/metals were present in significantly higher concentrations in EC/EH aerosol than in cigarette smoke. Concentrations of particular elements/metals within EC/EH brands were sometimes variable. Aerosols generated at low and high air-flow rates produced the same pattern of elements, although the total element concentration decreased at the higher air flow rate. The relative amount of elements in the first and last 60 puffs was generally different. Silicon was the dominant element in aerosols from all EC/EH brands and in cigarette smoke. The elements appeared to come from the filament (nickel, chromium), thick wire (copper coated with silver), brass clamp (copper, zinc), solder joints (tin, lead), and wick and sheath (silicon, oxygen, calcium, magnesium, aluminum). Lead was identified in the solder and aerosol of two brands of EHs (up to 0.165 μg/10 puffs). These data show that EC/EH aerosols contain a mixture of elements, including heavy metals, with concentrations often significantly higher than in conventional cigarette smoke. While the health effects of inhaling mixtures of heated metals is currently not known, these data will be valuable in future risk assessments involving EC/EH elements/metals.

  5. Improved ion extraction from an electron cyclotron resonance ion source by a metal-dielectric-extraction electrode

    International Nuclear Information System (INIS)

    Schachter, L.; Dobrescu, S.; Stiebing, K.E.

    2006-01-01

    The goal of the experiment was to study the influence and the physics of the boundary region (between the plasma and the extraction potential) with direct impact on the source ion-beam output. A specially processed high-emissive metal-dielectric structure was installed on the extraction electrode of the Frankfurt 14 GHz electron cyclotron resonance ion source (ECRIS), forming a so-called metal-dielectric- (MD) extraction electrode. The emissive layer of the disk faced the plasma; its inner hole was about the size of the normal extraction hole of the ECRIS. The output of the ECRIS in the presence of the MD electrode was compared with the outputs for the standard configuration (overall stainless-steel plasma chamber) and with the same plasma chamber with the radial wall covered by a highly electron emissive MD liner that raise the plasma electron density and temperature. The charge state distributions of the argon ions extracted from the source show an important increase of the ion beam for the high charge states as compared to the standard situation whereas the low charge states are less reduced than in the case of the presence of a MD liner. Due to the special position of the dielectric layer, the MD electrode introduces a new effect, which is connected to its property of becoming a positively charged surface under electron and ion bombardment. The MD electrode creates a quasiconfinement of the peripheral ions in the extraction, those ions that are normally lost to a conducting extraction electrode

  6. Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations.

    Science.gov (United States)

    Dahlstrand, Henrik; Stark, André; Wick, Marius C; Anissian, Lucas; Hailer, Nils P; Weiss, Rüdiger J

    2017-10-01

    Background and purpose - Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods - 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome. Results - 15-year implant survival was similar in both groups (MoM 96% [95% CI 88-100] versus MoP 97% [95% CI 91-100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5 μg/L) compared with the MoP cohort (0.4 μg/L, p concentration was double in the MoM (2.2 μg/L) compared with the MoP cohort (1.0 μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93 μmol/L versus MoP 92 μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts. Interpretation - This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.

  7. Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters

    CERN Document Server

    Dash, Monika

    2013-01-01

    Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

  8. Integrated Microanalytical System for Simultaneous Voltammetric Measurements of Free Metal Ion Concentrations in Natural Waters

    OpenAIRE

    Noël, Stéphane; Tercier-Waeber, Mary-Lou; Lin, Lin; Buffle, Jacques; Guenat, Olivier; Koudelka-Hep, Milena

    2007-01-01

    A complexing gel integrated microelectrode (CGIME) for direct measurements of free metal ion concentrations in natural waters has been developed. It is prepared by the successive deposition of microlayers of a chelating resin, an antifouling agarose gel and Hg on a 100-interconnected Ir-based microelectrode array. The trace metals of interest are in a first step accumulated on the chelating resin in proportion to their free ion concentration in solution, then released in acidic solution and d...

  9. ANALYSIS OF VARIOUS METAL IONS IN SOME MEDICINAL PLANTS USING ATOMIC ABSORPTION SPECTROPHOTOMETER

    OpenAIRE

    Y.L. Ramachandra*, C. Ashajyothi and Padmalatha S. Rai

    2012-01-01

    Metal ions such as iron , lead, copper, nickel, cadmium , chromium and zinc were investigated in medicinally important plants Alstonia scholaris, Tabernaemontana coronariae, Asparagus racemosus, Mimosa pudica, Leucas aspera and Adhatoda vasica applying atomic absorption spectrophotometer techniques. The purpose of this study was to standardize various metal ion Contamination in indigenous medicinal plants. Maximum concentration of lead was present in Leucas aspera and Adhatoda vasica follo...

  10. Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae

    OpenAIRE

    Begg, Stephanie L.; Eijkelkamp, Bart A.; Luo, Zhenyao; Cou?ago, Rafael M.; Morey, Jacqueline R.; Maher, Megan J.; Ong, Cheryl-lynn Y.; McEwan, Alastair G.; Kobe, Bostjan; O?Mara, Megan L.; Paton, James C.; McDevitt, Christopher A.

    2015-01-01

    Cadmium is a transition metal ion that is highly toxic in biological systems. Although relatively rare in the Earth?s crust, anthropogenic release of cadmium since industrialization has increased biogeochemical cycling and the abundance of the ion in the biosphere. Despite this, the molecular basis of its toxicity remains unclear. Here we combine metal-accumulation assays, high-resolution structural data and biochemical analyses to show that cadmium toxicity, in Streptococcus pneumoniae, occu...

  11. Films of Transition Metal Complexes Including Ionic Liquids: Dramatic Effects of Processing Parameters and Substrate on the Film Morphology

    Science.gov (United States)

    Bayatpour, Sareh; Isik, Dilek; Santato, Clara

    2018-01-01

    Bis(2-phenylpyridine- C, N)(2,2'-bipyridine- N, N') iridium(III) hexafluorophosphate ([Ir(ppy)2(bpy)][PF6]) is an ionic transition-metal complex (iTMC) of interest for use in light-emitting electrochemical cells (LEECs). Films of [Ir(ppy)2(bpy)][PF6] blended with the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]), deposited on different substrates, have been investigated for their morphological features, which are expected to affect the functional properties of the films, e.g., charge carrier transport. In literature, ionic liquids have been included in films of transition-metal complexes (TMCs) to increase the ion mobility and improve the performance of LEECs. A systematic comparison between the morphology of pure [Ir(ppy)2(bpy)][PF6] films and [Ir(ppy)2(bpy)][PF6] films containing [BMIm][PF6] has been carried out on different types of substrate, namely Au-patterned SiO2, indium tin oxide (ITO), and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)-modified ITO. Although [Ir(ppy)2(bpy)][PF6] forms smooth films on SiO2, ITO, and PEDOT:PSS-modified ITO substrates, addition of [BMIm][PF6] caused formation of vertical, discontinuous aggregates, which are expected to be detrimental to charge transport in LEECs with planar architecture.

  12. Critical capture distances for highly charged ions above dielectric covered metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lake, R.E., E-mail: russell.lake@nist.gov [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Pomeroy, J.M. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Sosolik, C.E. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States)

    2011-06-01

    We model the first stage of the electronic interaction between an ion and a metal surface covered with a thin dielectric layer. Specifically, we seek to answer two questions. (i) As an ion approaches the surface from far away, does the first electron that it captures originate from the exposed dielectric layer or the metal underneath it? (ii) What is the ion's distance from the metal when the first electron is captured? To answer these questions, the classical potential that an electron is subject to during the interaction is calculated. The dielectric film is treated as a continuum with simple band structure. We input the parameters from recent experiments (Co with 1.5 nm thick Al{sub 2}O{sub 3} film) and found that (i) the first capture proceeds from the metal, and (ii) the dielectric film extends the distance threshold for first capture compared to a metal with no film.

  13. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya, E-mail: divya@chem.unipune.ac.in

    2015-05-15

    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu{sup 2+}, Fe{sup 2+}, Ni{sup 2+} and Zn{sup 2+} in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu{sup 2+}, Fe{sup 2+} and Ni{sup 2+} caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe{sup 2+}, Cu{sup 2+}, Ni{sup 2+} and Zn{sup 2+}. • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions.

  14. Sorption of toxic metal ions in aqueous environment using ...

    African Journals Online (AJOL)

    carbodithioate and imidazole-1-carbodithioate were employed as sorbents for heavy metals from aqueous environments. The equilibrating time, initial metal concentrations and sorbent mass for optimal adsorption were 40 min, 5 mg/ℓ and 8 mg, ...

  15. Polyrhodanine modified anodic aluminum oxide membrane for heavy metal ions removal.

    Science.gov (United States)

    Song, Jooyoung; Oh, Hyuntaek; Kong, Hyeyoung; Jang, Jyongsik

    2011-03-15

    Polyrhodanine was immobilized onto the inner surface of anodic aluminum oxide (AAO) membrane via vapor deposition polymerization method. The polyrhodanine modified membrane was applied to remove heavy metal ions from aqueous solution because polyrhodanine could be coordinated with specific metal ions. Several parameters such as initial metal concentration, contact time and metal species were evaluated systematically for uptake efficiencies of the fabricated membrane under continuous flow condition. Adsorption isotherms of Hg(II) ion on the AAO-polyrhodanine membrane were analyzed with Langmuir and Freundlich isotherm models. The adsorption rate of Hg(II) ion on the membrane was obeyed by a pseudo-second order equation, indicating the chemical adsorption. The maximum removal capacity of Hg(II) ion onto the fabricated membrane was measured to be 4.2 mmol/g polymer. The AAO-polyrhodanine membrane had also remarkable uptake performance toward Ag(I) and Pb(II) ions. Furthermore, the polyrhodanine modified membrane could be recycled after recovery process. These results demonstrated that the polyrhodanine modified AAO membrane provided potential applications for removing the hazardous heavy metal ions from wastewater. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. The Incorporation of Lithium Alloying Metals into Carbon Matrices for Lithium Ion Battery Anodes

    Science.gov (United States)

    Hays, Kevin A.

    An increased interest in renewable energies and alternative fuels has led to recognition of the necessity of wide scale adoption of the electric vehicle. Automotive manufacturers have striven to produce an electric vehicle that can match the range of their petroleum-fueled counterparts. However, the state-of-the-art lithium ion batteries used to power the current offerings still do not come close to the necessary energy density. The energy and power densities of the lithium ion batteries must be increased significantly if they are going to make electric vehicles a viable option. The chemistry of the lithium ion battery, based on lithium cobalt oxide cathodes and graphite anodes, is limited by the amount of lithium the cathode can provide and the anode will accept. While these materials have proven themselves in portable electronics over the past two decades, plausible higher energy alternatives do exist. The focus is of this study is on anode materials that could achieve a capacity of more than 3 times greater than that of graphite anodes. The lithium alloying anode materials investigated and reported herein include tin, arsenic, and gallium arsenide. These metals were synthesized with nanoscale dimensions, improving their electrochemical and mechanical properties. Each exhibits their own benefits and challenges, but all display opportunities for incorporation in lithium ion batteries. Tin is incorporated in multilayer graphene nanoshells by introducing small amounts of metal in the core and, separately, on the outside of these spheres. Electrolyte decomposition on the anode limits cycle life of the tin cores, however, tin vii oxides introduced outside of the multilayer graphene nanoshells have greatly improved long term battery performance. Arsenic is a lithium alloying metal that has largely been ignored by the research community to date. One of the first long term battery performance tests of arsenic is reported in this thesis. Anodes were made from nanoscale

  17. Metal ion release from silver soldering and laser welding caused by different types of mouthwash.

    Science.gov (United States)

    Erdogan, Ayse Tuygun; Nalbantgil, Didem; Ulkur, Feyza; Sahin, Fikrettin

    2015-07-01

    To compare metal ion release from samples welded with silver soldering and laser welding when immersed into mouthwashes with different ingredients. A total of 72 samples were prepared: 36 laser welded and 36 silver soldered. Four samples were chosen from each subgroup to study the morphologic changes on their surfaces via scanning electron microscopy (SEM). Each group was further divided into four groups where the samples were submerged into mouthwash containing sodium fluoride (NaF), mouthwash containing sodium fluoride + alcohol (NaF + alcohol), mouthwash containing chlorhexidine (CHX), or artificial saliva (AS) for 24 hours and removed thereafter. Subsequently, the metal ion release from the samples was measured with inductively coupled plasma mass spectrometry (ICP-MS). The metal ion release among the solutions and the welding methods were compared. The Kruskal-Wallis and analysis of variance (ANOVA) tests were used for the group comparisons, and post hoc Dunn multiple comparison test was utilized for the two group comparisons. The level of metal ion release from samples of silver soldering was higher than from samples of laser welding. Furthermore, greater amounts of nickel, chrome, and iron were released from silver soldering. With regard to the mouthwash solutions, the lowest amounts of metal ions were released in CHX, and the highest amounts of metal ions were released in NaF + alcohol. SEM images were in accord with these findings. The laser welding should be preferred over silver soldering. CHX can be recommended for patients who have welded appliances for orthodontic reasons.

  18. Biosorption of heavy metal ions from aqueous solution by red macroalgae.

    Science.gov (United States)

    Ibrahim, Wael M

    2011-09-15

    Biosorption is an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine algae has been reported to have high biosorption capacities for a number of heavy metal ions. In this study, four species of red seaweeds Corallina mediterranea, Galaxaura oblongata, Jania rubens and Pterocladia capillacea were examined to remove Co(II), Cd(II), Cr(III) and Pb(II) ions from aqueous solution. The experimental parameters that affect the biosorption process such as pH, contact time and biomass dosage were studied. The maximum biosorption capacity of metal ions was 105.2mg/g at biomass dosage 10 g/L, pH 5 and contact time 60 min. The biosorption efficiency of algal biomass for the removal of heavy metal ions from industrial wastewater was evaluated for two successive cycles. Galaxaura oblongata biomass was relatively more efficient to remove metal ions with mean biosorption efficiency of 84%. This study demonstrated that these seaweeds constitute a promising, efficient, cheap and biodegradable sorbent biomaterial for lowering the heavy metal pollution in the environment. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. New Nuclear Materials Including Non Metallic Fuel Elements. Vol. II. Proceedings of the Conference on New Nuclear Materials Technology, Including Non Metallic Fuel Elements

    International Nuclear Information System (INIS)

    1963-01-01

    One of the major aims of the International Atomic Energy Agency in furthering the peaceful uses of atomic energy is to encourage the development of economical nuclear power. Certainly, one of the more obvious methods of producing economical nuclear power is the development of economical fuels that can be used at high temperatures for long periods of time, and which have sufficient strength and integrity to operate under these conditions without permitting the release of fission products. In addition it is desirable that after irradiation these new fuels be economically reprocessed to reduce further the cost of the fuel cycle. As nuclear power becomes more and more competitive with conventional power the interest in new and more efficient higher-temperature fuels naturally increases rapidly. For these reasons, the Agency organized a Conference on New Nuclear Materials Technology, Including Non-Metallic Fuel Elements, which was held from 1 to 5 July 1963 at the International Hotel, Prague, with the assistance and co-operation of the Government of the Czechoslovak Socialist Republic. A total of 151 scientists attended, from 23 countries and 4 international organizations. The participants heard and discussed more than 60 scientific papers. The Agency wishes to thank the scientists who attended this Conference for their papers and for many spirited discussions that truly mark a successful meeting. The Agency wishes also to record its gratitude for the assistance and generous hospitality accorded the Conference, the participants and the Agency's staff by the Government of the Czechoslovak Socialist Republic and by the people of Prague. The scientific information contained in these Proceedings should help to quicken the pace of progress in the fabrication of new and m ore economical fuels, and it is hoped that these proceedings will be found useful to all workers in this and related fields

  20. Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

    Science.gov (United States)

    Duncan, Michael

    2006-03-01

    Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

  1. Extraction of alginate biopolymer present in marine alga sargassum filipendula and bioadsorption of metallic ions

    Directory of Open Access Journals (Sweden)

    Sirlei Jaiana Kleinübing

    2013-04-01

    Full Text Available This paper studies the bioadsorption of Pb2+, Cu2+, Cd2+ and Zn2+ ions by marine alga Sargassum filipendula and by the alginate biopolymer extracted from this alga. The objective is to evaluate the importance of this biopolymer in removing different metallic ions by the marine alga S. filipendula. In the equilibrium study, the same affinity order was observed for both bioadsorbents: Pb2+ > Cu2+ > Zn2+ > Cd2+. For Pb2+ and Cu2+ ions when the alginate is isolated and acting as bioadsorbents, adsorption capacities greater than those found for the alga were observed, indicating that it is the main component responsible for the removal of metallic ions. For Zn2+ and Cd2+ ions, greater bioadsorption capacities were observed for the alga, indicating that other functional groups of the alga, such as sulfates and amino, are also important in the bioadsorption of these ions.

  2. Heavy ion time-of-flight ERDA of high dose metal implanted germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dytlewski, N.; Evans, P.J.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics; Bunder, J. [New South Wales Univ., Wollongong, NSW (Australia). Wollongong Univ. Coll

    1996-12-31

    With the thick Ge substrates used in ion implantation, RBS can have difficulty in resolving the mass-depth ambiguities when analysing materials composed of mixtures of elements with nearly equal masses. Additional, and complimentary techniques are thus required. This paper reports the use of heavy ion time-of-flight elastic recoil detection analysis (ToF- ERDA), and conventional RBS in the analysis of Ge(100) implanted with high dose Ti and Cu ions from a MEWA ion source . Heavy ion ToF ERDA has been used to resolve, and profile the implanted transition metal species, and also to study any oxygen incorporation into the sample resulting from the implantation, or subsequential reactions with air or moisture. This work is part of a study on high dose metal ion implantation of medium atomic weight semiconductor materials. 13 refs., 6 figs.

  3. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

    NARCIS (Netherlands)

    Dunbar, R.C.; Steill, J.D.; Polfer, N.C.; Oomens, J.

    2013-01-01

    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  4. Determination of membrane hydration numbers of alkali metal ions by insertion in a conducting polymer

    DEFF Research Database (Denmark)

    Skaarup, Steen; Junaid Mohamed Jafeen, Mohamed; Careem, M.A.

    2010-01-01

    not necessarily define the same hydration shell. This work presents a systematic study of one special variant of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS-). The technique...

  5. Adsorption of heavy metal ions from aqueous solution by fly ash

    Energy Technology Data Exchange (ETDEWEB)

    I.J. Alinnora [Federal University of Technology, Owerri (Nigeria). Department of Pure and Industrial Chemistry

    2007-03-15

    The removal characteristics of lead and copper ions from aqueous solution by fly ash were investigated under various conditions of contact time, pH and temperature. The influence of pH of the metal ion solutions on the uptake levels of the metal ions by fly ash were carried out between pH 4 and 12. The level of uptake of Pb{sup 2+} and Cu{sup 2+} ions by the fly ash generally increased, but not in a progressive manner, at higher pH values. The effect of temperature on the uptake of Pb{sup 2+} and Cu{sup 2+} ions was investigated between 30{sup o}C and 60{sup o}C, the adsorption of being enhanced at the lowest temperature. Rate constants were evaluated in terms of a first-order kinetics. The rate constant, k for uptake of Pb{sup 2+} and Cu{sup 2+} ions were 1.77 10{sup -2}s{sup -1} and 2.11 10{sup -2}s{sup -1}, respectively. The experimental results underline the potential of coal fly ash for the recovery of metal ions from waste water. The main mechanisms involved in the removal of heavy metal ions from solution were adsorption at the surface of the fly ash and precipitation. 43 refs., 4 figs., 1 tab.

  6. Some ENDOR studies of 3d transition metal ions in semiconductors

    International Nuclear Information System (INIS)

    Engelen, P.P.J.

    1980-01-01

    The author considers 3d transition metal ions substituted in covalent semiconducting crystals. The magnitude of the contact hyperfine field at the 59 Co nucleus in cobalt doped CdS is determined. The results of an ENDOR study of supertransferred hyperfine interactions with nearest neighbour Ga ions in Mn doped GaP are presented. (G.T.H.)

  7. Use of a Silver Ion Selective Electrode for the Determination of Stability Constants of Metal Complexes

    OpenAIRE

    Akio, Yuchi; Hiroko, Wada; Genkichi, Nakagawa

    1985-01-01

    The potential response of a sulfide-based silver ion selective electrode was examined in various metal buffer solutions. In every system tested, the potential response of the electrode was rapid and the electrode potential correctly reflected the free silver ion concentration in the solution. The stability constants of silver complexes with seven ligands were determined. This electrode was used also to measure the free cyanide ion concentration in the solutions containing silver, cyanide and ...

  8. No Giant Two-Ion Anisotropy in the Heavy-Rare-Earth Metals

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A new Bose-operator expansion of tensor operators is applied to the heavy-rare-earth metals. The Er data for the cone phase have been analyzed successfully with single-ion anisotropy and isotropic exchange interaction. The Tb data can be understood on the same basis. The previously found large two......-ion anisotropy was due to an inadequate treatment of the large single-ion anisotropy leading to an incorrect expression for the spin-wave energy....

  9. Effects of complexing compounds on sorption of metal ions to cement

    Energy Technology Data Exchange (ETDEWEB)

    Loevgren, Lars [Umeaa Univ. (Sweden). Inorganic chemistry

    2005-12-15

    This present report is a literature review addressing the effects of complexing ligands on the sorption of radionuclides to solid materials of importance for repositories of radioactive waste. Focus is put on laboratory studies of metal ion adsorption to cement in presence of chelating agents under strongly alkaline conditions. As background information, metal sorption to different mineral and cement phases in ligand free systems is described. Furthermore, surface complexation model (SCM) theories are introduced. According to surface complexation theories these interactions occur at specific binding sites at the particle/water interface. Adsorption of cationic metals is stronger at high pH, and the adsorption of anions occurs preferentially at low pH. The adsorption of ions to mineral surfaces is a result of both chemical bonding and electrostatic attraction between the ions and charged mineral surfaces. By combining uptake data with spectroscopic information the sorption can be explained on a molecular level by structurally sound surface complexation models. Most of the metal sorption studies reviewed are dealing with minerals exhibiting oxygen atoms at their surfaces, mainly oxides of Fe(II,III) and Al(III), and aluminosilicates. Investigations of radionuclides are focused on clay minerals, above all montmorillonite and illite. Which mechanism that is governing the metal ion adsorption to a given mineral is to a large extent depending on the metal adsorbed. For instance, sorption of Ni to montmorillonite can occur by formation of inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and by formation of a Ni phyllosilicate phase parallel to montmorillonite layers. Also metal uptake to cement materials can occur by different mechanisms. Cationic metals can both be attached to cement (calcium silicate hydrate, CSH) and hardened cement paste (HCP) by formation of inner-sphere complexes at specific surface sites and by

  10. 18-Electron rule inspired Zintl-like ions composed of all transition metals.

    Science.gov (United States)

    Zhou, Jian; Giri, Santanab; Jena, Purusottam

    2014-10-07

    Zintl phase compounds constitute a unique class of compounds composed of metal cations and covalently bonded multiply charged cluster anions. Potential applications of these materials in solution chemistry and thermoelectric materials have given rise to renewed interest in the search for new Zintl ions. Up to now these ions have been mostly composed of group 13, 14, and 15 post-transition metal elements and no Zintl ions composed of all transition metal elements are known. Using gradient corrected density functional theory we show that the 18-electron rule can be applied to design a new class of Zintl-like ions composed of all transition metal atoms. We demonstrate this possibility by using Ti@Au12(2-) and Ni@Au6(2-) di-anions as examples of Zintl-like ions. Predictive capability of our approach is demonstrated by showing that FeH6(4-) in an already synthesized complex metal hydride, Mg2FeH6, is a Zintl-like ion, satisfying the 18-electron rule. We also show that novel Zintl phase compounds can be formed by using all transition metal Zintl-like ions as building blocks. For example, a two-dimensional periodic structure of Na2[Ti@Au12] is semiconducting and nonmagnetic while a one-dimensional periodic structure of Mg[Ti@Au12] is metallic and ferromagnetic. Our results open the door to the design and synthesis of a new class of Zintl-like ions and compounds with potential for applications.

  11. Density functional study of isoguanine tetrad and pentad sandwich complexes with alkali metal ions.

    Science.gov (United States)

    Meyer, Michael; Steinke, Thomas; Sühnel, Jürgen

    2007-02-01

    Isoguanine tetraplexes and pentaplexes contain two or more stacked polyads with intercalating metal ions. We report here the results of a density functional study of sandwiched isoguanine tetrad and pentad complexes consisting of two polyads with Na(+), K(+) and Rb(+) ions at the B3LYP level. In comparison to single polyad metal ion complexes, there is a trend towards increased non-planarity of the polyads in the sandwich complexes. In general, the pentad sandwiches have relatively planar polyad structures, whereas the tetrad complexes contain highly non-planar polyad building blocks. As in other sandwich complexes and in metal ion complexes with single polyads, the metal ion-base interaction energy plays an essential role. In iG sandwich structures, this interaction energy is slightly larger than in the corresponding guanine sandwich complexes. Because the base-base interaction energy is even more increased in passing from guanine to isoguanine, the isoguanine sandwiches are thus far the only examples where the base-base interaction energy is larger than the base-metal ion interaction energy. Stacking interactions have been studied in smaller models consisting of two bases, retaining the geometry from the complete complex structures. From the data obtained at the B3LYP and BH&H levels and with Møller-Plesset perturbation theory, one can conclude that the B3LYP method overestimates the repulsion in stacked base dimers. For the complexes studied in this work, this is only of minor importance because the direct inter-tetrad or inter-pentad interaction is supplemented by a strong metal ion-base interaction. Using a microsolvation model, the metal ion preference K(+) approximately Rb(+) > Na(+) is found for tetrad complexes. On the other hand, for pentads the ordering is Rb(+) > K(+) > Na(+). In the latter case experimental data are available that agree with this prediction.

  12. Label-free histamine detection with nanofluidic diodes through metal ion displacement mechanism.

    Science.gov (United States)

    Ali, Mubarak; Ramirez, Patricio; Duznovic, Ivana; Nasir, Saima; Mafe, Salvador; Ensinger, Wolfgang

    2017-02-01

    We design and characterize a nanofluidic device for the label-free specific detection of histamine neurotransmitter based on a metal ion displacement mechanism. The sensor consists of an asymmetric polymer nanopore fabricated via ion track-etching technique. The nanopore sensor surface having metal-nitrilotriacetic (NTA-Ni 2+ ) chelates is obtained by covalent coupling of native carboxylic acid groups with N α ,N α -bis(carboxymethyl)-l-lysine (BCML), followed by exposure to Ni 2+ ion solution. The BCML immobilization and subsequent Ni 2+ ion complexation with NTA moieties change the surface charge concentration, which has a significant impact on the current-voltage (I-V) curve after chemical modification of the nanopore. The sensing mechanism is based on the displacement of the metal ion from the NTA-Ni 2+ chelates. When the modified pore is exposed to histamine solution, the Ni 2+ ion in NTA-Ni 2+ chelate recognizes histamine through a metal ion coordination displacement process and formation of stable Ni-histamine complexes, leading to the regeneration of metal-free NTA groups on the pore surface, as shown in the current-voltage characteristics. Nanomolar concentrations of the histamine in the working electrolyte can be detected. On the contrary, other neurotransmitters such as glycine, serotonin, gamma-aminobutyric acid, and dopamine do not provoke significant changes in the nanopore electronic signal due to their inability to displace the metal ion and form a stable complex with Ni 2+ ion. The nanofluidic sensor exhibits high sensitivity, specificity and reusability towards histamine detection and can then be used to monitor the concentration of biological important neurotransmitters. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Poultry litter-based activated carbon for removing heavy metal ions in water.

    Science.gov (United States)

    Guo, Mingxin; Qiu, Guannan; Song, Weiping

    2010-02-01

    Utilization of poultry litter as a precursor material to manufacture activated carbon for treating heavy metal-contaminated water is a value-added strategy for recycling the organic waste. Batch adsorption experiments were conducted to investigate kinetics, isotherms, and capacity of poultry litter-based activated carbon for removing heavy metal ions in water. It was revealed that poultry litter-based activated carbon possessed significantly higher adsorption affinity and capacity for heavy metals than commercial activated carbons derived from bituminous coal and coconut shell. Adsorption of metal ions onto poultry litter-based carbon was rapid and followed Sigmoidal Chapman patterns as a function of contact time. Adsorption isotherms could be described by different models such as Langmuir and Freundlich equations, depending on the metal species and the coexistence of other metal ions. Potentially 404 mmol of Cu2+, 945 mmol of Pb2+, 236 mmol of Zn2+, and 250-300 mmol of Cd2+ would be adsorbed per kg of poultry litter-derived activated carbon. Releases of nutrients and metal ions from litter-derived carbon did not pose secondary water contamination risks. The study suggests that poultry litter can be utilized as a precursor material for economically manufacturing granular activated carbon that is to be used in wastewater treatment for removing heavy metals.

  14. Removal of toxic heavy metal ions in runoffs by modified alfalfa and juniper

    Science.gov (United States)

    J.S. Han; J.K. Park; S.H. Min

    2000-01-01

    A series of batch isotherm tests was performed with alfalfa and juniper fibers to evaluate the effectiveness in filtering toxic heavy metals from stormwater. The adsorption of the heavy metal ions on the alfalfa and juniper fibers was strongly dependent on the equilibrium pH value of the solution. The change in sorption rate over time showed that two different sorption...

  15. Effect of surface modification of microfiltration membrane on capture of toxic heavy metal ions.

    Science.gov (United States)

    Madaeni, Sayed Siavash; Heidary, Farhad

    2012-01-01

    A novel complexing membrane containing 8-hydroxyquinoline groups was used for the removal of heavy metal ions (Cd2+ and Ni2+) from aqueous solution. The functionalized membranes were characterized by FTIR-ATR, SEM and EDAX for the presence of functional groups, the physical structure of the membranes and the analysis of the particles deposited on the membrane, respectively. The influence of 8-hydroxyquinoline concentration, feed concentration, pH and temperature of the solution on capture capability was studied. The modified membrane showed a higher affinity to Cd2+ cations than to Ni2+. The metal ion rejection was increased with an increase in concentration of 8-hydroxyquinoline from 0.5 to 2.0 wt%. However at a ligand concentration higher than 2.0 wt%, no significant change was observed in the metal rejection. The experimental results revealed that the metal rejection was decreased with an increase in metal ion concentration in the feed. Moreover the rejection depended on feed pH and is higher for elevated pH. By changing the temperature in the range of 23-28 degrees C, no considerable effect on metal rejection was observed. However, a higher temperature resulted in a decline in metal rejection. For filtration of a mixture of the two metal ions, the retention was similar to that of the single cations, i.e. Cd > Ni but with smaller absolute rejections.

  16. Examining metallic glass formation in LaCe:Nb by ion implantation

    Directory of Open Access Journals (Sweden)

    Sisson Richard

    2017-01-01

    Full Text Available In order to combine niobium (Nb with lanthanum (La and cerium (Ce, Nb ions were deposited within a thin film of these two elements. According to the Hume-Rothery rules, these elements cannot be combined into a traditional crystalline metallic solid. The creation of an amorphous metallic glass consisting of Nb, La, and Ce is then investigated. Amorphous metallic glasses are traditionally made using fast cooling of a solution of molten metals. In this paper, we show the results of an experiment carried out to form a metallic glass by implanting 9 MeV Nb 3+ atoms into a thin film of La and Ce. Prior to implantation, the ion volume distribution is calculated by Monte Carlo simulation using the SRIM tool suite. Using multiple methods of electron microscopy and material characterization, small quantities of amorphous metallic glass are indeed identified.

  17. Strong Cation···π Interactions Promote the Capture of Metal Ions within Metal-Seamed Nanocapsule

    Science.gov (United States)

    2015-01-01

    Thallium ions are transported to the interior of gallium-seamed pyrogallol[4]arene nanocapsules. In comparison to the capture of Cs ions, the extent of which depends on the type and position of the anion employed in the cesium salt, the enhanced strength of Tl···π vs Cs···π interactions facilitates permanent entrapment of Tl+ ions on the capsule interior. “Stitching-up” the capsule seam with a tertiary metal (Zn, Rb, or K) affords new trimetallic nanocapsules in solid state. PMID:25405777

  18. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions

    Science.gov (United States)

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-01

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu3 +) ion. Upon addition of Eu3 + ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y3 +, Ce3 +, Pr3 +, Nd3 +, Sm3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Yb3 + and Lu3 +, into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu3 + ions were investigated, including solution pH value, Eu3 + ion concentration and interfering substances. The detection mechanism of Eu3 + ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of EuIII-dtpa-bis(cytosine) at 375 nm in the concentration range of 0.50 × 10- 5 mol • L- 1-5.00 × 10- 5 mol • L- 1 of Eu3 + ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65 × 10- 7 mol • L- 1 and the corresponding correlation coefficient (R2) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu3 + ion.

  19. Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

    KAUST Repository

    Chen, Ye

    2017-01-26

    Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets. The composition has high conductivity and flexibility. The composition can be made by a one-pot synthesis in which a graphene material precursor is converted to the graphene material, and the metal precursor is converted to the metal. A reducing solvent or dispersant such as NMP can be used. Devices made from the composition include a pressure sensor which has high sensitivity. Two two- dimension materials can be combined to form a hybrid material.

  20. Generation of oxygen, carbon and metallic ion beams by a compact microwave source

    Energy Technology Data Exchange (ETDEWEB)

    Walther, S.R.; Leung, K.N.; Ehlers, K.W.; Kunkel, W.B.

    1986-07-01

    A small microwave ion source fabricated from a quartz tube and enclosed externally by a cavity has been operated with different geometries and for various gases in a cw mode. This source has been used to generate oxygen ion beams with energy as low as 5.5 eV. Beam energy spread has been measured to be less than 1 eV. By installing different metal plates on the front extraction electrode, metallic ion beams such as (Be, Cu, Al, etc.) can be produced.

  1. Effects of metal ions in tea polysaccharides on their in vitro antioxidant activity and hypoglycemic activity.

    Science.gov (United States)

    Fan, Minghao; Sun, Xun; Qian, Yilin; Xu, Ying; Wang, Dongfeng; Cao, Yanping

    2018-01-09

    Total tea polysaccharides (TTPS) were extracted from two kinds of pruning leaves of tea plant and fractionated into neutral tea polysaccharides (TPSI) and acidic tea polysaccharides (TPSII) by anion exchange resin D315. Some physicochemical properties, including structure, monosaccharide composition, and molecular weight distribution, as well as the 4 in vitro antioxidant activities and inhibitory effects on α-glucosidase of above polysaccharides before and after removing metal ions were investigated. By comparing TTPS and TPSII, we found that they exhibited different antioxidant activities and inhibitory actions against α-glucosidase after their metal ions were removed. However, the in vitro antioxidant activities and inhibitory effects on α-glucosidase of TPSI were substantially improved. The study can be a certain reference for tea and soil selection. At the same time, we suggested that pruning leaves of tea plant could be treated as a potential resource for the development of polysaccharide antioxidants and hypoglycemic products. Copyright © 2018. Published by Elsevier B.V.

  2. A dipeptide-based superhydrogel: Removal of toxic dyes and heavy metal ions from waste water.

    Science.gov (United States)

    Nandi, Nibedita; Baral, Abhishek; Basu, Kingshuk; Roy, Subhasish; Banerjee, Arindam

    2017-01-01

    A short peptide-based molecule has been found to form a strong hydrogel at phosphate buffer solution of pH 7.46. The hydrogel has been characterized thoroughly using various techniques including field emission scanning electron microscopy (FE-SEM), wide angle powder X-ray diffraction (PXRD), and rheological analysis. It has been observed from FE-SEM images that entangled nanofiber network is responsible for gelation. Rheological investigation demonstrates that the self-assembly of this synthetic dipeptide results in the formation of mechanically strong hydrogel with storage modulus (G') around 10 4 Pa. This gel has been used for removing both cationic and anionic toxic organic dyes (Brilliant Blue, Congo red, Malachite Green, Rhodamine B) and metal ions (Co 2+ and Ni 2+ ) from waste water. Moreover, only a small amount of the gelator is required (less than 1 mg/mL) for preparation of this superhydrogel and even this hydrogel can be reused three times for dye/metal ion absorption. This signifies the importance of the hydrogel towards waste water management. © 2016 Wiley Periodicals, Inc.

  3. Metal ions diffusion through polymeric matrices: A total reflection X-ray fluorescence study

    International Nuclear Information System (INIS)

    Boeykens, S.; Caracciolo, N.; D'Angelo, M.V.; Vazquez, C.

    2006-01-01

    This work proposes the use of X-ray fluorescence with total reflection geometry to explore the metal ions transport in aqueous hydrophilic polymer solutions. It is centered in the study of polymer concentration influence on ion diffusion. This subject is relevant to various and diverse applications, such as drug controlled release, microbiologic corrosion protection and enhanced oil recovery. It is anticipated that diffusion is influenced by various factors in these systems, including those specific to the diffusing species, such as charge, shape, molecular size, and those related to the structural complexity of the matrix as well as any specific interaction between the diffusing species and the matrix. The diffusion of nitrate salts of Ba and Mn (same charge, different hydrodynamic radii) through water-swollen polymeric solutions and gels in the 0.01% to 1% concentration ranges was investigated. The measurements of the metal concentration were performed by TXRF analysis using the scattered radiation by the sample as internal standard. Results are discussed according to different physical models for solute diffusion in polymeric solutions

  4. Molecular-Scale Investigation of Heavy Metal Ions at a Charged Langmuir Monolayer

    Science.gov (United States)

    Rock, William; Qiao, Baofu; Uysal, Ahmet; Bu, Wei; Lin, Binhua

    Solvent extraction - the surfactant-aided preferential transfer of a species from an aqueous to an organic phase - is an important technique used in heavy and precious metal refining and reprocessing. Solvent extraction requires transfer through an oil/water interface, and interfacial interactions are expected to control transfer kinetics and phase stability, yet these key interactions are poorly understood. Langmuir monolayers with charged headgroups atop concentrated salt solutions containing heavy metal ions act as a model of solvent extraction interfaces; studies of ions at a charged surface are also fundamentally important to many other phenomena including protein solvation, mineral surface chemistry, and electrochemistry. We probe these charged interfaces using a variety of surface-sensitive techniques - vibrational sum frequency generation (VSFG) spectroscopy, x-ray reflectivity (XRR), x-ray fluorescence near total reflection (XFNTR), and grazing incidence diffraction (GID). We integrate experiments with Molecular Dynamics (MD) simulations to uncover the molecular-level interfacial structure. This work is supported by the U.S. DOE, BES, Contract DE-AC02-06CH11357. ChemMatCARS is supported by NSF/CHE-1346572.

  5. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-01

    We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense...... surface coverage is achieved by the introduction of a flexible linking molecule. The resulting hybrid composite is highly stable and is capable of detecting potassium ions down to micromolar ranges with a selectivity over other cations (including Ca2+, Li+, Na+, NH4+) at concentrations up to 25 m......M. This material can be combined further with disposable chips, demonstrating its promise as an effective ion-selective sensing component for practical applications....

  6. Effect of ion beam irradiation on metal particle doped polymer ...

    Indian Academy of Sciences (India)

    Polymethyl methacrylate (PMMA) was prepared by solution polymerization method. Different concentrations (10, 20 and 40%) of Ni powder were dispersed in PMMA and the composite films were prepared by casting method. These films were irradiated with 120 MeV Ni 10 + ions at a fluence of 5 × 1012 ions/cm2. Electrical ...

  7. Transport of Alkali Metal Ions through a Liquid Membrane System ...

    African Journals Online (AJOL)

    crown-6, [K(MF18C6)](picrate) was determined by X-ray crystallography and showed that each potassium ion is eight-coordinate; each K+ ion is coordinated to the six oxygen atoms of the crown, to the phenolate oxygen atom and to one of the ...

  8. Application of mucilage from Dicerocaryum eriocarpum plant as biosorption medium in the removal of selected heavy metal ions.

    Science.gov (United States)

    Jones, Bassey O; John, Odiyo O; Luke, Chimuka; Ochieng, Aoyi; Bassey, Bridget J

    2016-07-15

    The ability of mucilage from Dicerocaryum eriocarpum (DE) plant to act as biosorption medium in the removal of metals ions from aqueous solution was investigated. Functional groups present in the mucilage were identified using Fourier transform infrared spectroscopy (FTIR). Mucilage was modified with sodium and potassium chlorides. This was aimed at assessing the biosorption efficiency of modified mucilage: potassium mucilage (PCE) and sodium mucilage (SCE) and comparing it with non-modified deionised water mucilage (DCE) in the uptake of metal ions. FTIR results showed that the functional groups providing the active sites in PCE and SCE and DCE include: carboxyl, hydroxyl and carbonyl groups. The chloride used in the modification of the mucilage did not introduce new functional groups but increased the intensity of the already existing functional groups in the mucilage. Results from biosorption experiment showed that DE mucilage displays good binding affinity with metals ions [Zn(II), Cd(II) Ni(II), Cr(III) and Fe(II)] in the aqueous solution. Increase in the aqueous solution pH, metal ions initial concentration and mucilage concentration increased the biosorption efficiency of DE mucilage. The maximum contact time varied with each species of metal ions. Optimum pH for [Zn(II), Cd(II) Ni(II) and Fe(II)] occurred at pH 4 and pH 6 for Cr(III). Kinetic models result fitted well to pseudo-second-order with a coefficient values of R(2) = 1 for Cd(II), Ni(II), Cr(III), Fe(II) and R(2) = 0.9974 for Zn(II). Biosorption isotherms conforms best with Freundlich model for all the metal ions with correlation factors of 0.9994, 0.9987, 0.9554, 0.9621 and 0.937 for Zn(II), Ni(II), Fe(II), Cr(III) and Cd(II), respectively. Biosorption capacity of DE mucilage was 0.010, 2.387, 4.902, 0688 and 0.125 for Zn(II), Cr(III), Fe(II), Cd(II) and Ni(II) respectively. The modified mucilage was found to be highly efficient in the removal of metal ions than the unmodified mucilage

  9. Removal of Heavy Metal Ions from Polluted Waters by Using of Low Cost Adsorbents: Review

    Directory of Open Access Journals (Sweden)

    M. Ghaedi

    2013-06-01

    Full Text Available Adsorption is a fundamental process in the physicochemical treatment of wastewaters which industries employ to reduce hazardous organic and inorganic wastes in effluents. In recent years the use of low-cost adsorbents has been widely investigated as a replacement for the currently costly methods of removing heavy metal ions from wastewater. 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 this study, the use of some of low cost adsorbents for the removal of heavy metals from wastewater has been reviewed.

  10. Comparative evaluation of different extractants towards cloud point extraction of metal ions

    International Nuclear Information System (INIS)

    Kumari, Neelam; Pathak, P.N.; Mohapatra, P.K.

    2014-01-01

    The cloud formation behavior of nonionic surfactant Triton X-114 (1,1,3,3-Tetramethylbutyl) phenyl-polyethylene glycol; t-Oct-C 6 H 4 -(OCH 2 CH 2 ) x OH, x = 7-8) was investigated in Na-acetate medium. The effects of organic dopents (often added for metal extractions) such as dibenzoylmethan(DBM), and thenoyltrifluoroacetone (HTTA) on metal ions (viz. U(VI), Am(III), Sr(II), and Cs(I)) extraction were investigated. Extraction (%) of metal ions followed the order: U(VI) > Am(III) > Sr(II) > Cs(I). (author)

  11. Study of highly functionalized metal surface treated by plasma ion implantation

    International Nuclear Information System (INIS)

    Ikeyama, Masami; Miyagawa, Soji; Miyagawa, Yoshiko; Nakao, Setsuo; Masuda, Haruho; Saito, Kazuo; Ono, Taizou; Hayashi, Eiji

    2004-01-01

    Technology for processing metal surfaces with hardness, low friction and free from foreign substances was developed with plasma ion implantation. Diamond-like carbon (DLC) coating is a most promising method for realization of hard and smooth metal surface. DLC coating was tested in a metal pipe with 10 mm diameter and 10 cm length by a newly developed plasma ion implantation instrument. The surface coated by DLC was proved to have characteristics equivalent to those prepared with other methods. A computer program simulating a formation process of DLC coating was developed. Experiments for fluorinating the DLC coating surface was performed. (Y. Kazumata)

  12. Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines

    Directory of Open Access Journals (Sweden)

    M. Manuela M Raposo

    2007-10-01

    Full Text Available The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II and Ni(II metal ions and with diamagnetic Hg(II, as shown by theabsorption and steady-state fluorescence spectroscopy studies. The formation ofmononuclear or dinuclear metal complexes was postulated based on the presence of thefree carboxylic acid as binding site and also with the interaction with the donor atoms inthe chromophore. Interaction with other important biological metal ions such as Zn(II,Ca(II and Na(I was also explored.

  13. Colorimetric photonic hydrogel aptasensor for the screening of heavy metal ions.

    Science.gov (United States)

    Ye, Bao-Fen; Zhao, Yuan-Jin; Cheng, Yao; Li, Ting-Ting; Xie, Zhuo-Ying; Zhao, Xiang-Wei; Gu, Zhong-Ze

    2012-09-28

    We have developed a robust method for the visual detection of heavy metal ions (such as Hg(2+) and Pb(2+)) by using aptamer-functionalized colloidal photonic crystal hydrogel (CPCH) films. The CPCHs were derived from a colloidal crystal array of monodisperse silica nanoparticles, which were polymerized within the polyacrylamide hydrogel. The heavy metal ion-responsive aptamers were then cross-linked in the hydrogel network. During detection, the specific binding of heavy metal ions and cross-linked single-stranded aptamers in the hydrogel network caused the hydrogel to shrink, which was detected as a corresponding blue shift in the Bragg diffraction peak position of the CPCHs. The shift value could be used to estimate, quantitatively, the amount of the target ion. It was demonstrated that our CPCH aptasensor could screen a wide concentration range of heavy metal ions with high selectivity and reversibility. In addition, these aptasensors could be rehydrated from dried gels for storage and aptamer protection. It is anticipated that our technology may also be used in the screening of a broad range of metal ions in food, drugs and the environment.

  14. The effect of hydrogen peroxide concentration on metal ion release from dental amalgam.

    Science.gov (United States)

    Al-Salehi, S K; Hatton, P V; McLeod, C W; Cox, A G

    2007-02-01

    The aim of this study was to investigate the effect of hydrogen peroxide (HP) concentration on metal ion release from dental amalgam. Dental amalgam discs (n=25) were prepared by packing amalgam into cylindrical plastic moulds (10 mm diameter and 2 mm height). The discs were divided into five equal groups and each group was immersed in 20 ml of either 0%, 1%, 3%, 10% or 30% HP solution for 24 h at 37 degrees C. Samples were taken for metal ion release determination (Hg, Ag, Sn and Cu) using inductively coupled plasma mass spectrometry (ICP-MS). The surface roughness of each disc was measured before and after bleaching. The differences in concentration of metal ions released after treatment with 0% (control) and each of 1%, 3%, 10% and 30% HP were statistically significant (pp>0.05). Exposure to HP bleaching agent was associated with increased metal ion released from dental amalgams compared to treatment with a control solution. Ion release was in proportion to the peroxide concentration tested, with the highest concentration associated with the greatest metal ion release for all elements investigated.

  15. Heavy metal ions in wines: meta-analysis of target hazard quotients reveal health risks

    Directory of Open Access Journals (Sweden)

    Petróczi Andrea

    2008-10-01

    Full Text Available Abstract Background Metal ions such as iron and copper are among the key nutrients that must be provided by dietary sources. Numerous foodstuffs have been evaluated for their contributions to the recommended daily allowance both to guide for satisfactory intake and also to prevent over exposure. In the case of heavy metal ions, the focus is often on exposure to potentially toxic levels of ions such as lead and mercury. The aim of this study is to determine target hazard quotients (THQ from literature reports giving empirical levels of metal ions in table wines using the reference upper safe limit value. Contributions to the THQ value were calculated for seven metal ions along with total values for each wine. Results The THQ values were determined as ranges from previously reported ranges of metal ion concentrations and were frequently concerningly high. Apart from the wines selected from Italy, Brazil and Argentina, all other wines exhibited THQ values significantly greater than one indicating levels of risk. The levels of vanadium, copper and manganese had the highest impact on THQ measures. Typical potential maximum THQ values ranged from 50 to 200 with Hungarian and Slovakian wines reaching 300. THQ values for a sample of red and white wines were high for both having values ranging from 30 to 80 for females based on a 250 mL glass per day. Conclusion The THQ values calculated are concerning in that they are mainly above the safe level of THQ

  16. The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys.

    Science.gov (United States)

    Al-Salehi, S K; Hatton, P V; Johnson, A; Cox, A G; McLeod, C

    2008-04-01

    There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P Metal ion release from the two alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.

  17. Influence of the inert and active ion bombardment on structure of the transition metal thin films

    CERN Document Server

    Blazhevich, S; Martynov, I; Neklyudov, I

    2002-01-01

    The results of the experimental research of the inert (He, Ne, Ar, Kr, Xe) and active (O, N) ion impact on the transition metal structure are presented. Thin high-purity (99.999 at.%) films of nickel, chrome and iron were used in the experiment. The bombardment was realized under room temperature at high vacuum (P<1x10 sup - sup 7 Pa) by a separated ion beam of 10-10 sup 3 keV. As a main result of the experiment, the full absence of crystal matrix changes was ascertained for all the transition metals irradiated by inert gas ions. The chemical nature of the crystal structure changes observed in transition metals being under active ion bombardment was found out too.

  18. Angular and mass resolved energy distribution measurements with a gallium liquid metal ion source

    International Nuclear Information System (INIS)

    Marriott, Philip

    1987-06-01

    Ionisation and energy broadening mechanisms relevant to liquid metal ion sources are discussed. A review of experimental results giving a picture of source operation and a discussion of the emission mechanisms thought to occur for the ionic species and droplets emitted is presented. Further work is suggested by this review and an analysis system for angular and mass resolved energy distribution measurements of liquid metal ion source beams has been constructed. The energy analyser has been calibrated and a series of measurements, both on and off the beam axis, of 69 Ga + , Ga ++ and Ga 2 + ions emitted at various currents from a gallium source has been performed. A comparison is made between these results and published work where possible, and the results are discussed with the aim of determining the emission and energy spread mechanisms operating in the gallium liquid metal ion source. (author)

  19. Dislocation structures and strengthening of ion-implanted metals and alloys

    Science.gov (United States)

    Sharkeev, Yu. P.; Didenko, A. N.; Kozlov, É. V.

    1994-05-01

    This article surveys the empirical data on the “long-range effect” (changes in defect structure and physicomechanical properties at distances considerably exceeding the mean free path of ions) seen in the ion implantation of metallic materials and semiconductors. Results are presented from electron-microscope studies of dislocation structures formed in ion-implanted metallic materials which are initially in different states. It is shown that the character of the dislocation structure and its quantitative characteristics in ion-implanted metals and alloys depend on the initial state of the target, the species and energy of the ions, and the radiation dose. Data obtained on the change in microstructure with depth is combined with data from other authors and correlated with the results of a study of macroscopic characteristics (wear resistance, microhardness). It is established that the “long-range effect” is seen in metallic materials which, in addition to having a low yield point or a high degree of plastic strain, also have a low dislocation density prior to ion implantation. Mechanisms by which the defect structure might be modified by ion implantation are explored.

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

    Science.gov (United States)

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

    2013-05-02

    A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Surface enhanced Raman spectroscopy as a new spectral technique for quantitative detection of metal ions.

    Science.gov (United States)

    Temiz, Havva Tumay; Boyaci, Ismail Hakki; Grabchev, Ivo; Tamer, Ugur

    2013-12-01

    Four newly synthesized poly (propylene amine) dendrimers from first and second generation modified with 1,8-naphthalimide units in the dendrimer periphery have been investigated as ligands for the detection of heavy metal ions (Al(3+), Sb(2+), As(2+), Cd(2+) and Pb(2+)) by surface-enhanced Raman spectroscopy. Calibration curves were established for all metal ions between the concentration ranges of 1 x 10(-6) to 5 x 10(-4) M. It has been shown that these dendrimers can be coordinated, especially with different metal ions. Using dendrimer molecules and silver colloids at the same time allowed us to obtain an SERS signal from the abovementioned metal ions at very low concentrations. Principle component analysis (PCA) analysis was also applied to the collected SERS data. Four different PCA models were developed to accomplish the discrimination of five metal ions, which interacted with each of the four dendrimer molecules, separately. A detailed investigation was performed in the present study to provide the basis of a new approach for heavy metal detection. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Adsorption of heavy metal ions on molybdenum and molybdenum trioxide from dilute aqueous solution

    International Nuclear Information System (INIS)

    Utsunomiya, Taizo; Hoshino, Yoshio; Sakabe, Ken-ichi

    1984-01-01

    The adsorption of heavy metal ions such as Co(II), Cu(II) and Pb(II) on molybdenum powder has been investigated by the batch technique as a function of soaking time, concentration of heavy metal ions and coexisting salts, pH etc. Molybdenum trioxide was also used as an adsorbent for a comparison to discuss the adsorption mechanism. The amount of these heavy metal ions adsorbed was highly pH and coexisting salts dependent. These adsorbents have features of selective adsorption for Pb(II) and large adsorption rate. The adsorption of heavy metal ions on these adsorbents proceeds independently or concurrently by following complex mechanism; (1) cation exchange reaction by hydroxyl radical on the surface of Mo and MoO 3 is predominant for most of heavy metal ions except Pb(II) [Co(II), Mn(II), Fe(III), Ni(II), Zn(II), Cd(II) and Sr(II)], (2) reduction (electron exchange reaction) to low ionic or metallic state after cation exchange reaction [Cu(II) and Ag(I) on Mo] and (3) formation of a compound [Pb(II) on both Mo and MoO 3 ]. (author)

  3. Effects of metal ions on growth, β-oxidation system, and thioesterase activity of Lactococcus lactis.

    Science.gov (United States)

    Li, Liang; Ma, Ying

    2014-10-01

    The effects of divalent metal ions (Ca(2+), Mg(2+), Fe(2+), and Cu(2+)) on the growth, β-oxidation system, and thioesterase activity of Lactococcus lactis were investigated. Different metal ions significantly influenced the growth of L. lactis: Ca(2+) and Fe(2+) accelerated growth, whereas Cu(2+) inhibited growth. Furthermore, Mg(2+) inhibited growth of L. lactis at a low concentration but stimulated growth of L. lactis at a high concentration. The divalent metal ions had significant effects on activity of the 4 key enzymes of the β-oxidation system (acyl-CoA dehydrogenase, enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and thiolase) and thioesterase of L. lactis. The activity of acyl-CoA dehydrogenases increased markedly in the presence of Ca(2+) and Mg(2+), whereas it decreased with 1 mmol/L Fe(2+) or 12 mmol/L Mg(2+). All the metal ions could induce activity of enoyl-CoA hydratase. In addition, 12 mmol/L Mg(2+) significantly stimulated activity of L-3-hydroxyacyl-CoA dehydrogenase, and all metal ions could induce activity of thiolase, although thiolase activity decreased significantly when 0.05 mmol/L Cu(2+) was added into M17 broth. Inhibition of thioesterase activity by all 4 metal ions could be reversed by 2 mmol/L Ca(2+). These results help us understand the effect of metal ions on the β-oxidation system and thioesterase activity of Lactococcus lactis. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  4. Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol–gel method

    International Nuclear Information System (INIS)

    Palza, Humberto; Escobar, Blanca; Bejarano, Julian; Bravo, Denisse; Diaz-Dosque, Mario; Perez, Javier

    2013-01-01

    Bioactive glasses (SiO 2 –P 2 O 5 –CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol–gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria. - Highlights: • Copper and silver act as antimicrobial additives in bioactive glass materials. • Silver is more toxic than copper ions in these bioactive materials. • Sol–gel method allows the synthesis of antimicrobial bioactive materials

  5. Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Palza, Humberto, E-mail: hpalza@ing.uchile.cl [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile); Escobar, Blanca; Bejarano, Julian [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile); Bravo, Denisse [Departamento de Patología, Facultad de Odontología, Universidad de Chile, Santiago (Chile); Diaz-Dosque, Mario [Departamento de Ciencias Básicas y Comunitarias, Facultad de Odontología, Universidad de Chile, Santiago (Chile); Perez, Javier [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile)

    2013-10-15

    Bioactive glasses (SiO{sub 2}–P{sub 2}O{sub 5}–CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol–gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria. - Highlights: • Copper and silver act as antimicrobial additives in bioactive glass materials. • Silver is more toxic than copper ions in these bioactive materials. • Sol–gel method allows the synthesis of antimicrobial bioactive materials.

  6. Investigation of the complexation of metal-ions by strong ligands in fresh and marine water.

    Science.gov (United States)

    Pesavento, Maria; Biesuz, Raffaela; Profumo, Antonella; Soldi, Teresa

    2003-01-01

    The detection and investigation of metal ions bound in strong complexes in natural waters is a difficult task, due to low concentration of the metal ions themselves, and also of the strong ligands, which, moreover, are often not of a well-defined composition. Here, a method is proposed for the investigation of the speciation of metal ions in natural waters. It is based on the sorption of metal ions on strongly sorbing ion exchange resins, i.e. complexing resins. For this reason the method is called Resin Titration. It has been shown in previous investigations that the concentration of metal ion totally sorbed by a particular resin, and its reaction coefficient in the solution phase in the presence of the resin, can be determined from the sorption data using a simple relationship. Here, a data treatment (the Ruzic linearization method) is proposed for also determining the concentration of the ligands responsible for the complex in equilibrium with the resin. The method was applied to data obtained by Resin Titration of a freshwater and a seawater. Copper(II) and aluminium(III) were considered, using Chelex 100 as a titrant, due to its strong sorbing properties towards these metal ions. The results were: the total metal concentration in equilibrium with the resin, the side reaction coefficients, and the concentration of ligands. In all these cases the ligands forming very strong complexes were found to be at concentration lower than that of the metals. The Ruzic linearization method allows the determination of the concentration of the ligands forming very strong complexes in equilibrium with Chelex 100. The reaction coefficient was better determined by the calculation method previously proposed for RT. The ligands responsible for the strong complexes were found to be at low concentration, often lower than that of the metal ions considered. The metal in the original sample is partly bound to these ligands, since the complexes are very strong. Only a part of the metal

  7. Adsorption of strontium (II) metal ions using phosphonate ...

    Indian Academy of Sciences (India)

    analysis and solubility. The synthesized polymer was used for sequestering strontium metal from the aqueous solu- tion. The metal binding was examined by the energy dispersive spectroscopy and scanning electron microscopy for the adsorbed Sr(II). Batch adsorption studies were performed by varying three parameters, ...

  8. Adsorption of strontium (II) metal ions using phosphonate ...

    Indian Academy of Sciences (India)

    The synthesized polymer was used for sequestering strontium metal from the aqueous solu- tion. The metal binding was examined by the energy dispersive spectroscopy and scanning electron microscopy for the adsorbed Sr(II). Batch adsorption studies were performed by varying three parameters, namely initial pH, adsor-.

  9. A high resolution mass-energy spectrometer for the study of liquid metal ion sources

    International Nuclear Information System (INIS)

    Wilkens, B.

    1985-01-01

    A sector-magnet mass spectrometer has been modified to allow measurement of ion energy deficit and distributions as well as measurement of various mass species and their abundance to be made. The energy calibration and resolution measurement was achieved by using a simple, low cost, Cs surface ionization source which supplied monoenergetic Cs + and Cs + 2 ions of known energy. This energy analyzer has a resolution of < 2 eV and a mass energy product of 2 meV amu in the configuration in which it was used. Data are presented illustrating the versatility of the spectrometer in studying ion production mechanisms in liquid metal ion sources. (orig.)

  10. Theory Meets Experiment: Metal Ion Effects in HCV Genomic RNA Kissing Complex Formation

    OpenAIRE

    Sun, Li-Zhen; Heng, Xiao; Chen, Shi-Jie

    2017-01-01

    The long-range base pairing between the 5BSL3. 2 and 3′X domains in hepatitis C virus (HCV) genomic RNA is essential for viral replication. Experimental evidence points to the critical role of metal ions, especially Mg2+ ions, in the formation of the 5BSL3.2:3′X kissing complex. Furthermore, NMR studies suggested an important ion-dependent conformational switch in the kissing process. However, for a long time, mechanistic understanding of the ion effects for the process has been unclear. Rece...

  11. Competitive removal of heavy metal ions from squid oil under isothermal condition by CR11 chelate ion exchanger.

    Science.gov (United States)

    Tavakoli, Omid; Goodarzi, Vahabodin; Saeb, Mohammad Reza; Mahmoodi, Niyaz Mohammad; Borja, Rafael

    2017-07-15

    Heavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu 2+ , Pb 2+ , Cd 2+ and Zn 2+ ) was studied from aqueous phase to oil phase (493, 523, 548, and 573K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu 2+ (96%, isotherm 573K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb 2+ and Cd 2+ was the same in the OIL, with maximum values of 5.7×10 -3 (mol/l) and 5.0×10 -3 (mol/l) at 573K, respectively. By contrast, concentration of Zn 2+ ion showed a slight increase with increasing temperature due to electrostatic forces between Zn 2+ and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn 2+ , was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Protein scaffolds for selective enrichment of metal ions

    Science.gov (United States)

    He, Chuan; Zhou, Lu; Bosscher, Michael

    2016-02-09

    Polypeptides comprising high affinity for the uranyl ion are provided. Methods for binding uranyl using such proteins are likewise provided and can be used, for example, in methods for uranium purification or removal.

  13. Metal ion-dependent, reversible, protein filament formation by designed beta-roll polypeptides

    Science.gov (United States)

    Scotter, Andrew J; Guo, Meng; Tomczak, Melanie M; Daley, Margaret E; Campbell, Robert L; Oko, Richard J; Bateman, David A; Chakrabartty, Avijit; Sykes, Brian D; Davies, Peter L

    2007-01-01

    Background A right-handed, calcium-dependent β-roll structure found in secreted proteases and repeat-in-toxin proteins was used as a template for the design of minimal, soluble, monomeric polypeptides that would fold in the presence of Ca2+. Two polypeptides were synthesised to contain two and four metal-binding sites, respectively, and exploit stacked tryptophan pairs to stabilise the fold and report on the conformational state of the polypeptide. Results Initial analysis of the two polypeptides in the presence of calcium suggested the polypeptides were disordered. The addition of lanthanum to these peptides caused aggregation. Upon further study by right angle light scattering and electron microscopy, the aggregates were identified as ordered protein filaments that required lanthanum to polymerize. These filaments could be disassembled by the addition of a chelating agent. A simple head-to-tail model is proposed for filament formation that explains the metal ion-dependency. The model is supported by the capping of one of the polypeptides with biotin, which disrupts filament formation and provides the ability to control the average length of the filaments. Conclusion Metal ion-dependent, reversible protein filament formation is demonstrated for two designed polypeptides. The polypeptides form filaments that are approximately 3 nm in diameter and several hundred nm in length. They are not amyloid-like in nature as demonstrated by their behaviour in the presence of congo red and thioflavin T. A capping strategy allows for the control of filament length and for potential applications including the "decoration" of a protein filament with various functional moieties. PMID:17908326

  14. Carbon nanotubes paste sensor modified with bismuth film for determination of metallic ions in ethanol fuel

    Directory of Open Access Journals (Sweden)

    Felipe Augusto Gorla

    2015-05-01

    Full Text Available In the present study an anodic stripping voltammetric method using a bismuth film modified carbon nanotubes paste electrode for simultaneous determination of metals Zn2+, Cd2+and Pb2+in ethanol fuel is described. The metallic ions were preconcentrated on the bismuth film in the time and deposition potential of 500 s and -1.2 V and the stripping step was carried out by square wave voltammetry (frequency of 15 Hz, pulse amplitude of 25 mV and potential step of 5 mV. Acetate buffer at 0.1 mol L-1concentration and pH 4.5 was used as support electrolyte. The method showed linearity including the analytical blank up to 48.39 ?g L-1 for the metals and the obtained limits of detection were 3.36, 0.32 and 0.47 ?g L-1for Zn2+, Cd2+and Pb2+, respectively. The proposed method was applied in ethanol fuel samples.

  15. Water-soluble polymers for recovery of metal ions from aqueous streams

    Science.gov (United States)

    Smith, Barbara F.; Robison, Thomas W.

    1998-01-01

    A process of selectively separating a target metal contained in an aqueous solution by contacting the aqueous solution containing a target metal with an aqueous solution including a water-soluble polymer capable of binding with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solution is disclosed.

  16. Coordination ability determined transition metal ions substitution of Tb in Tb-Asp fluorescent nanocrystals and a facile ions-detection approach.

    Science.gov (United States)

    Duan, Jiazhi; Ma, Baojin; Liu, Feng; Zhang, Shan; Wang, Shicai; Kong, Ying; Du, Min; Han, Lin; Wang, Jianjun; Sang, Yuanhua; Liu, Hong

    2018-04-11

    Although the synthesis and fluorescent properties of lanthanide-amino acid complex nanostructures have been investigated extensively, limited studies have been reported on metal ions' substitution ability for the lanthanide ions in the complex and their effect on the fluorescent property. In this study, taking biocompatible Tb-aspartic acid (Tb-Asp) complex nanocrystals as a model, the substitution mechanism of metal ions, particularly transition metals, for Tb ions in Tb-Asp nanocrystals and the change in the fluorescent property of the Tb-Asp nanocrystals after substitution were systematically investigated. The experimental results illustrated that metal ions with higher electronegativity, higher valence, and smaller radius possess stronger ability for Tb ions' substitution in Tb-Asp nanocrystals. Based on the effect of substituting ions' concentration on the fluorescent property of Tb-Asp, a facile method for copper ions detection with high sensitivity was proposed by measuring the fluorescent intensity of Tb-Asp nanocrystals' suspensions containing different concentrations of copper ions. The good biocompatibility, great convenience of synthesis and sensitive detection ability make Tb-Asp nanocrystals a very low cost and effective material for metal ions detection, which also opens a new door for practical applications of metal-Asp coordinated nanocrystals.

  17. The Analysis of Metal Finishing Solutions by Ion Chromatography

    Science.gov (United States)

    1987-08-01

    but some Cr(III) is produced during the electrolysis and can negatively effect plate properties and plating efficiency (67, 68). In an operating system... Brines by Indirect Atomic Absorption Spectroscopy", Chem. Prum., 33, 8, 429- 435 (1983). 17. D. Jones, S. Manahan, "Atomic Absorption Detector For... Brine ", J. Chromatogr., 250, 134-7 (1982). 24. T. Nishina, "Analysis of Sulfate Ion by Ion Chromatography", Yogyo Kyokaishi, 92, 7, 410-2 (1984). 25. S

  18. Selective removal of heavy metal ions by disulfide linked polymer networks.

    Science.gov (United States)

    Ko, Dongah; Lee, Joo Sung; Patel, Hasmukh A; Jakobsen, Mogens H; Hwang, Yuhoon; Yavuz, Cafer T; Hansen, Hans Chr Bruun; Andersen, Henrik R

    2017-06-15

    Heavy metal contaminated surface water is one of the oldest pollution problems, which is critical to ecosystems and human health. We devised disulfide linked polymer networks and employed as a sorbent for removing heavy metal ions from contaminated water. Although the polymer network material has a moderate surface area, it demonstrated cadmium removal efficiency equivalent to highly porous activated carbon while it showed 16 times faster sorption kinetics compared to activated carbon, owing to the high affinity of cadmium towards disulfide and thiol functionality in the polymer network. The metal sorption mechanism on polymer network was studied by sorption kinetics, effect of pH, and metal complexation. We observed that the metal ions-copper, cadmium, and zinc showed high binding affinity in polymer network, even in the presence of competing cations like calcium in water. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

    Zhang Jianhua; Wang Naiyan; Zhang Fengshou

    2012-01-01

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

  20. Supercharging with Trivalent Metal Ions in Native Mass Spectrometry

    Science.gov (United States)

    Flick, Tawnya G.; Williams, Evan R.

    2012-11-01

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

  1. Mass-spectrometric study of ion clustering in alkali-metal hydroxide vapor: cluster-ion energy and structural characteristics

    International Nuclear Information System (INIS)

    Kudin, L.S.; Butman, M.F.; Krasnov, K.S.

    1986-01-01

    Various positive and negative ions have been recorded in the equilibrium vapors from alkali-metal hydroxides: M/sup +/-/, OH - , O - , MO - , MOH - , and X/sup +/-/ (MOH)/sub n/, where X = M/sup +/-/, OH - , n = 1-6. The equilibrium constants have been measured for X/sup +/-/(MOH)/sub n/ = x/sup +/-/ + nMOH(k), n = 1-3, and the enthalpies of reaction have been determined, from which the enthalpies of formation and dissociation energies of X/sup +/-/ (MOH)/sub n/ have been calculated. The relative stabilities of the ions in the series from Na to Cs are examined

  2. Essential oils and metal ions as alternative antimicrobial agents: a focus on tea tree oil and silver.

    Science.gov (United States)

    Low, Wan-Li; Kenward, Ken; Britland, Stephen T; Amin, Mohd Cim; Martin, Claire

    2017-04-01

    The increasing occurrence of hospital-acquired infections and the emerging problems posed by antibiotic-resistant microbial strains have both contributed to the escalating cost of treatment. The presence of infection at the wound site can potentially stall the healing process at the inflammatory stage, leading to the development of a chronic wound. Traditional wound treatment regimes can no longer cope with the complications posed by antibiotic-resistant strains; hence, there is a need to explore the use of alternative antimicrobial agents. Pre-antibiotic compounds, including heavy metal ions and essential oils, have been re-investigated for their potential use as effective antimicrobial agents. Essential oils have potent antimicrobial, antifungal, antiviral, anti-inflammatory, antioxidant and other beneficial therapeutic properties. Similarly, heavy metal ions have also been used as disinfecting agents because of their broad spectrum activities. Both of these alternative antimicrobials interact with many different intracellular components, thereby resulting in the disruption of vital cell functions and eventually cell death. This review will discuss the application of essential oils and heavy metal ions, particularly tea tree oil and silver ions, as alternative antimicrobial agents for the treatment of chronic, infected wounds. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  3. Neutralizing mutations of carboxylates that bind metal 2 in T5 flap endonuclease result in an enzyme that still requires two metal ions.

    Science.gov (United States)

    Tomlinson, Christopher G; Syson, Karl; Sengerová, Blanka; Atack, John M; Sayers, Jon R; Swanson, Linda; Tainer, John A; Williams, Nicholas H; Grasby, Jane A

    2011-09-02

    Flap endonucleases (FENs) are divalent metal ion-dependent phosphodiesterases. Metallonucleases are often assigned a "two-metal ion mechanism" where both metals contact the scissile phosphate diester. The spacing of the two metal ions observed in T5FEN structures appears to preclude this mechanism. However, the overall reaction catalyzed by wild type (WT) T5FEN requires three Mg(2+) ions, implying that a third ion is needed during catalysis, and so a two-metal ion mechanism remains possible. To investigate the positions of the ions required for chemistry, a mutant T5FEN was studied where metal 2 (M2) ligands are altered to eliminate this binding site. In contrast to WT T5FEN, the overall reaction catalyzed by D201I/D204S required two ions, but over the concentration range of Mg(2+) tested, maximal rate data were fitted to a single binding isotherm. Calcium ions do not support FEN catalysis and inhibit the reactions supported by viable metal cofactors. To establish participation of ions in stabilization of enzyme-substrate complexes, dissociation constants of WT and D201I/D204S-substrate complexes were studied as a function of [Ca(2+)]. At pH 9.3 (maximal rate conditions), Ca(2+) substantially stabilized both complexes. Inhibition of viable cofactor supported reactions of WT, and D201I/D204S T5FENs was biphasic with respect to Ca(2+) and ultimately dependent on 1/[Ca(2+)](2). By varying the concentration of viable metal cofactor, Ca(2+) ions were shown to inhibit competitively displacing two catalytic ions. Combined analyses imply that M2 is not involved in chemical catalysis but plays a role in substrate binding, and thus a two-metal ion mechanism is plausible.

  4. Neutralizing Mutations of Carboxylates That Bind Metal 2 in T5 Flap Endonuclease Result in an Enzyme That Still Requires Two Metal Ions*

    Science.gov (United States)

    Tomlinson, Christopher G.; Syson, Karl; Sengerová, Blanka; Atack, John M.; Sayers, Jon R.; Swanson, Linda; Tainer, John A.; Williams, Nicholas H.; Grasby, Jane A.

    2011-01-01

    Flap endonucleases (FENs) are divalent metal ion-dependent phosphodiesterases. Metallonucleases are often assigned a “two-metal ion mechanism” where both metals contact the scissile phosphate diester. The spacing of the two metal ions observed in T5FEN structures appears to preclude this mechanism. However, the overall reaction catalyzed by wild type (WT) T5FEN requires three Mg2+ ions, implying that a third ion is needed during catalysis, and so a two-metal ion mechanism remains possible. To investigate the positions of the ions required for chemistry, a mutant T5FEN was studied where metal 2 (M2) ligands are altered to eliminate this binding site. In contrast to WT T5FEN, the overall reaction catalyzed by D201I/D204S required two ions, but over the concentration range of Mg2+ tested, maximal rate data were fitted to a single binding isotherm. Calcium ions do not support FEN catalysis and inhibit the reactions supported by viable metal cofactors. To establish participation of ions in stabilization of enzyme-substrate complexes, dissociation constants of WT and D201I/D204S-substrate complexes were studied as a function of [Ca2+]. At pH 9.3 (maximal rate conditions), Ca2+ substantially stabilized both complexes. Inhibition of viable cofactor supported reactions of WT, and D201I/D204S T5FENs was biphasic with respect to Ca2+ and ultimately dependent on 1/[Ca2+]2. By varying the concentration of viable metal cofactor, Ca2+ ions were shown to inhibit competitively displacing two catalytic ions. Combined analyses imply that M2 is not involved in chemical catalysis but plays a role in substrate binding, and thus a two-metal ion mechanism is plausible. PMID:21734257

  5. A mononuclear non-heme manganese(IV)-oxo complex binding redox-inactive metal ions.

    Science.gov (United States)

    Chen, Junying; Lee, Yong-Min; Davis, Katherine M; Wu, Xiujuan; Seo, Mi Sook; Cho, Kyung-Bin; Yoon, Heejung; Park, Young Jun; Fukuzumi, Shunichi; Pushkar, Yulia N; Nam, Wonwoo

    2013-05-01

    Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal-oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)-oxo complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)-oxo complex binding scandium ions. The Mn(IV)-oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)-oxo complex are markedly influenced by binding of Sc(3+) ions in oxidation reactions, such as a ~2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ~180-fold decrease in the rate of C-H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)-oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal-oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.

  6. On-site preconcentration and trace metal ions determination in the Okavango Delta water system, Botswana.

    Science.gov (United States)

    Sawula, G M

    2004-09-08

    Microcolumns containing 8-hydroxyquinoline azo-immobilized on controlled pore glass were incorporated in a field sampler for on-site collection, isolation and preconcentration of trace metal ions in waters of the Okavango Delta, Botswana. Sequestered trace metal ions were recovered by elution with 0.5ml of 1.5M nitric acid, and determined by graphite furnace atomic absorption spectrometry (GFAAS). This sampling and enrichment method minimizes sample contamination, and collection of large volumes of water samples for transporting, over long distances, to analytical laboratories is avoided. Data reported comprise one of the initial surveys on trace metal ion concentrations in waters of the Okavango Delta, Botswana. In waters with more efficient mixing, dissolved metal ion concentrations found were generally low with slightly elevated levels of manganese (7-19mugl(-1)), zinc (2.7-4.8mugl(-1)), nickel (0.2-2.5mugl(-1)) and copper (0.3-2.1mugl(-1)). For each trace metal ion, concentration levels seem to reflect zones of varying water conveyance, and show no obvious temporal and spatial variations apart from a slight increment from the inlet in the upper Delta to the outlets in the lower Delta.

  7. FTIR spectroscopy structural analysis of the interaction between Lactobacillus kefir S-layers and metal ions

    Science.gov (United States)

    Gerbino, E.; Mobili, P.; Tymczyszyn, E.; Fausto, R.; Gómez-Zavaglia, A.

    2011-02-01

    FTIR spectroscopy was used to structurally characterize the interaction of S-layer proteins extracted from two strains of Lactobacillus kefir (the aggregating CIDCA 8348 and the non-aggregating JCM 5818) with metal ions (Cd +2, Zn +2, Pb +2 and Ni +2). The infrared spectra indicate that the metal/protein interaction occurs mainly through the carboxylate groups of the side chains of Asp and Glut residues, with some contribution of the NH groups belonging to the peptide backbone. The frequency separation between the νCOO - anti-symmetric and symmetric stretching vibrations in the spectra of the S-layers in presence of the metal ions was found to be ca. 190 cm -1 for S-layer CIDCA 8348 and ca. 170 cm -1 for JCM 5818, denoting an unidentate coordination in both cases. Changes in the secondary structures of the S-layers induced by the interaction with the metal ions were also noticed: a general trend to increase the amount of β-sheet structures and to reduce the amount of α-helices was observed. These changes allow the proteins to adjust their structure to the presence of the metal ions at minimum energy expense, and accordingly, these adjustments were found to be more important for the bigger ions.

  8. Anion-intercalated layered double hydroxides modified test strips for detection of heavy metal ions.

    Science.gov (United States)

    Wang, Nan; Sun, Jianchao; Fan, Hai; Ai, Shiyun

    2016-01-01

    In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)6(4-) or S(2-) anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10(-6) mol L(-1). Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Surface-Functionalized Electrospun Titania Nanofibers for the Scavenging and Recycling of Precious Metal Ions.

    Science.gov (United States)

    Dai, Yunqian; Formo, Eric; Li, Haoxuan; Xue, Jiajia; Xia, Younan

    2016-10-20

    Precious metals are widely used as catalysts in industry. It is of critical importance to keep the precious metal ions leached from catalysts at a level below one part per million (ppm) in the final products and to recycle the expensive precious metals. Here we demonstrate a simple and effective method for scavenging precious metal ions from an aqueous solution and thereby reduce their concentrations down to the parts per billion (ppb) level. The key component is a filtration membrane comprised of titania (TiO 2 ) nanofibers whose surface has been functionalized with a silane bearing amino or thiol group. When operated under continuous flow at a rate of 1 mL min -1 and at room temperature, up to 99.95 % of the Pd 2+ ions could be removed from a stock solution with an initial concentration of 100 ppm. This work offers a viable strategy not only for the removal of precious metal ions but also for recovering and further recycling them for use as catalysts. For example, the captured Pd 2+ ions could be converted to nanoparticles and used as catalysts for organic reactions such as Suzuki coupling in a continuous flow reactor. This system can be potentially applied to pharmaceutical industry and waste stream treatment. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Metal ions accelerated phytosterol thermal degradation on Ring A & Ring B of steroid nucleus in oils.

    Science.gov (United States)

    Hu, Yinzhou; Huang, Weisu; Li, Maiquan; Wang, Mengmeng; Zhao, Yajing; Xu, Tao; Zhang, Liuquan; Lu, Baiyi; He, Yan

    2017-10-01

    This study aimed to investigate the effect of metal ions on the degradation of phytosterols in oils. The oil was heated at 180°C for 1h with/without addition of Fe 3+ , Fe 2+ , Cu 2+ , Mn 2+ , Zn 2+ , Na + , Al 3+ and Mg 2+ . Variations of β-sitosterol, stigmasterol, campesterol, brassicasterol and their degradation products were confirmed by the GC-MS analysis. In general, the increase of the metal ion concentration resulted in more phytosterol degradation, and the ability of metal ions following decreasing order: Fe 3+ >Fe 2+ >Mn 2+ ≥Cu 2+ ≥Zn 2+ >Na + ≥Mg 2+ >Al 3+ . Metal ions significantly induced phytosterol autoxidation on C5, C6 and C7 on Ring B of steroid nucleus at even a low concentration, and induced dehydration on the C3 hydroxyl to form dienes and trienes at high concentration. The metal ions in oils are accounted for increasing phytosterol degradation, which decreases food nutritional quality and gives rise to the formation of undesirable compounds. Copyright © 2017. Published by Elsevier Ltd.

  11. Effect Of Metal Ions On Triphenylmethane Dye Decolorization By Laccase From Trametes Versicolor

    Directory of Open Access Journals (Sweden)

    Chmelová Daniela

    2015-12-01

    Full Text Available The aim of this study was investigate the influence of different metal ions on laccase activity and triphenylmethane dye decolorization by laccase from white-rot fungus Trametes versicolor. Laccase activity was inhibited by monovalent ions (Li+, Na+, K+ and Ag+ but the presence of divalent ions increased laccase activity at the concentration of 10 mmol/l. The effect of metal ions on decolorization of triphenylmethane dyes with different structures namely Bromochlorophenol Blue, Bromophenol Blue, Bromocresol Blue and Phenol Red was tested. The presence of metal ions (Na+, K+, Mg2+, Ca2+, Ba2+, Mn2+, Zn2+ slightly decreased triphenylmethane dye decolorization by laccase from T. versicolor except Na+ and Mg2+, which caused the increase of decolorization for all tested dyes. Decolorization of selected dyes showed that the presence of low-molecular-weight compounds is necessary for effective decolorization. Hydroxybenzotriazole (HBT is the most frequently used. Although HBT belongs to most frequently used redox mediator and generally increase decolorization efficiency, so its presence decreased decolorization percentage of Bromophenol Blue and Bromochlorophenol Blue, the influence of metal ions to dye decolorization by laccase has the similar course with or without presence of redox mediator HBT.

  12. [In vitro analysis of the impact of metal ions on human lymphocyte cultures].

    Science.gov (United States)

    Hagmann, S; Kirsch, J; Kretzer, J P; Moradi, B

    2013-08-01

    The use of metal implants has become increasingly more frequent in all fields of medicine throughout the past decades. Numerous studies have demonstrated that metal ions released from these implants can be detected in body fluids remote from the implants. Although diseases directly linked to the release of these ions seem to be rare, the general public is unsettled. In this study we aimed to analyze the impact of molybdenum(V), cobalt(II), chromium(III) and nickel(II) ions on cell surface markers (CD25, CD38, CD69, CD95) and viability (7-AAD/AnnexinV) of human CD4+ T-lymphocytes in vitro. Cobalt(II) ions at a concentration of 1000 μg/l led to a significant suppression of lymphocyte activation markers while nickel(II), chromium(III) and molybdenum(V) did not show any significant impact on these lymphocyte activation markers. Cell viability was significantly reduced by all metal ions, whereas cobalt(II) led to the highest increase of apoptotic cells and was the only metal ion to significantly increase the necrosis rate. While the pathophysiological significance of these findings remains unclear, they are in favour of further research in this field.

  13. Influence of metal ions intercalation on the vibrational dynamics of water confined between MXene layers

    Science.gov (United States)

    Osti, Naresh C.; Naguib, Michael; Ganeshan, Karthik; Shin, Yun K.; Ostadhossein, Alireza; van Duin, Adri C. T.; Cheng, Yongqiang; Daemen, Luke L.; Gogotsi, Yury; Mamontov, Eugene; Kolesnikov, Alexander I.

    2017-11-01

    Two-dimensional (2D) carbides and nitrides of early transition metals (MXenes) combine high conductivity with hydrophilic surfaces, which make them promising for energy storage, electrocatalysis, and water desalination. The effects of intercalated metal ions on the vibrational states of water confined in Ti3C2Tx MXenes have been explored using inelastic neutron scattering (INS) and molecular-dynamics simulations to better understand the mechanisms that control MXenes' behavior in aqueous electrolytes, water purification, and other important applications. We observe an INS signal from water in all samples, pristine and with lithium, sodium, or potassium ions intercalated between the 2D Ti3C2Tx layers. However, only a small amount of water is found to reside in Ti3C2Tx intercalated with metal ions. Water in pristine Ti3C2Tx is more disordered, with bulklike characteristics, in contrast to intercalated Ti3C2Tx , where water is more ordered, irrespective of the metal ions used for intercalation. The ordering of the confined water increases with the ion size. This finding is further confirmed from molecular-dynamics simulation, which showed an increase in interference of water molecules with increasing ion size resulting in a concomitant decrease in water mobility, therefore providing guidance to tailor MXene properties for energy and environmental applications.

  14. Determination of metal ion content of beverages and estimation of target hazard quotients: a comparative study

    Directory of Open Access Journals (Sweden)

    Barker James

    2008-06-01

    Full Text Available Abstract Background Considerable research has been directed towards the roles of metal ions in nutrition with metal ion toxicity attracting particular attention. The aim of this study is to measure the levels of metal ions found in selected beverages (red wine, stout and apple juice and to determine their potential detrimental effects via calculation of the Target Hazard Quotients (THQ for 250 mL daily consumption. Results The levels (mean ± SEM and diversity of metals determined by ICP-MS were highest for red wine samples (30 metals totalling 5620.54 ± 123.86 ppb followed by apple juice (15 metals totalling 1339.87 ± 10.84 ppb and stout (14 metals totalling 464.85 ± 46.74 ppb. The combined THQ values were determined based upon levels of V, Cr, Mn, Ni, Cu, Zn and Pb which gave red wine samples the highest value (5100.96 ± 118.93 ppb followed by apple juice (666.44 ± 7.67 ppb and stout (328.41 ± 42.36 ppb. The THQ values were as follows: apple juice (male 3.11, female 3.87, stout (male 1.84, female 2.19, red wine (male 126.52, female 157.22 and ultra-filtered red wine (male 110.48, female 137.29. Conclusion This study reports relatively high levels of metal ions in red wine, which give a very high THQ value suggesting potential hazardous exposure over a lifetime for those who consume at least 250 mL daily. In addition to the known hazardous metals (e.g. Pb, many metals (e.g. Rb have not had their biological effects systematically investigated and hence the impact of sustained ingestion is not known.

  15. Polymer-supported reagents with enhanced metal ion recognition: Application to separations science

    International Nuclear Information System (INIS)

    Alexandratos, S.D.

    1993-01-01

    The design and development of polymer-supported reagents with ever-increasing specificities for targeted metal ions remains an important areas of research. The need for efficient separation schemes for both ions and molecules has been outlined in a report by the National Research Council (King) and will gain increased emphasis as environmental restoration is pursued. Polymer-supported reagents are unique in their ability to be applied in an environmentally benign manner to a host of challenges. Such reagents, in the form of beads, can be applied to continuous separation processes ranging from the removal of metal ions in water to the recovery of medicinal drugs produced through biotechnological means. The application of polymer-supported reagents to metal ion separations still requires developing a fundamental understanding of ligand-metal interactions, the role of the polymer in those interactions, and the methods of synthesizing such polymeric reagents in a readily applicable form. Ion exchange resins with sulfonic acid ligands are the prototypical polymer-supported reagents, and their properties have been exhaustively studied (Helfferich). The high acidity of the sulfonic acid group, however, precludes much selectivity, and it displays a very limited range of reaction free energy values with different metal ions (Boyd et al.). The carboxylic acid ligand, present in the acrylate resins, is more selective, though its weak acidity requires relatively high pH solutions for it to be effective. Research has thus been focused on the preparation of polymer-supported reagents with high levels of specificity for targeted metal ions

  16. Ion chromatography of transition metals: specific alteration of retention by complexation reactions in the mobile and on the stationary phase

    International Nuclear Information System (INIS)

    Baumgartner, S.

    1992-05-01

    Ion chromatography of mono- and bivalent cations was performed on a conventional cation exchanger. The pH influence of an ethylene-diamine/citrate eluent was significant for the retention of alkaline earth and transition metals, but negligible for alkali ions. This was dealt with from a mechanistic point of view. Mobile phase optimization allowed fast isocratic analysis of mono- and bivalent cations and the separation of the radionuclides Cs-137 and Sr-90. A newly synthesized stationary phase containing iminodiacetate (IDA) function was investigated for cation chromatography using ethylenediamine/citrate eluents, polyhydroxy acid and dipicolinic acid. The column's high selectivity for transition metal ions in comparison to alkali and alkaline earth metals may be governed by the choice of complexing ability and pH of the eluent. Applications verified by atomic absorption spectroscopy include alkaline earth metals in beverages and the determination of Co, Cd and Zn in solutions containing more than 10 14 -fold excess of Na and Mg, such as sea water

  17. Ion activity and distribution of heavy metals in acid mine drainage polluted subtropical soils

    International Nuclear Information System (INIS)

    Li Yongtao; Becquer, Thierry; Dai Jun; Quantin, Cecile; Benedetti, Marc F.

    2009-01-01

    The oxidative dissolution of mine wastes gives rise to acidic, metal-enriched mine drainage (AMD) and has typically posed an additional risk to the environment. The poly-metallic mine Dabaoshan in South China is an excellent test site to understand the processes affecting the surrounding polluted agricultural fields. Our objectives were firstly to investigate metal ion activity in soil solution, distribution in solid constituents, and spatial distribution in samples, secondly to determine dominant environment factors controlling metal activity in the long-term AMD-polluted subtropical soils. Soil Column Donnan Membrane Technology (SC-DMT) combined with sequential extraction shows that unusually large proportion of the metal ions are present as free ion in the soil solutions. The narrow range of low pH values prevents any pH effects during the binding onto oxides or organic matter. The differences in speciation of the soil solutions may explain the different soil degradation observed between paddy and non-paddy soils. - First evidence of the real free metal ion concentrations in acid mine drainage context in tropical systems

  18. Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol-gel method.

    Science.gov (United States)

    Palza, Humberto; Escobar, Blanca; Bejarano, Julian; Bravo, Denisse; Diaz-Dosque, Mario; Perez, Javier

    2013-10-01

    Bioactive glasses (SiO2-P2O5-CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol-gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Effect of Nanoemitters on Suppressing the Formation of Metal Adduct Ions in Electrospray Ionization Mass Spectrometry.

    Science.gov (United States)

    Hu, Jun; Guan, Qi-Yuan; Wang, Jiang; Jiang, Xiao-Xiao; Wu, Zeng-Qiang; Xia, Xing-Hua; Xu, Jing-Juan; Chen, Hong-Yuan

    2017-02-07

    In the work, we showed that the use of nanoemitters (tip dimension metal adduction to peptide or protein ions as well as improve the matrix tolerance of electrospray ionization mass spectrometry (ESI-MS). The proton-enriched smaller initial droplets are supposed to have played a significant role in suppressing the formation of metal adduct ions in nanoemitters. The proton-enrichment effect in the nanoemitters is related to both the exclusion-enrichment effect (EEE) and the ion concentration polarization effect (ICP effect), which permit the molecular ions to be regulated to protonated ones. Smaller initial charged droplets generated from nanoemitters need less fission steps to release the gas-phase ions; thus, the enrichment effect of salt was not as significant as that of microemitters (tip dimension >1 μm), resulting in the disappearing of salt cluster peaks in high mass-to-charge (m/z) region. The use of nanoemitters demonstrates a novel method for tuning the distribution of the metal-adducted ions to be in a controlled manner. This method is also characterized by ease of use and high efficiency in eliminating the formation of adduct ions, and no pretreatment such as desalting is needed even in the presence of salt at millimole concentration.

  20. Effect of dimensions of multi-walled carbon nanotubes on its enrichment efficiency of metal ions from environmental waters

    Energy Technology Data Exchange (ETDEWEB)

    El-Sheikh, Amjad H. [Department of Chemistry, Faculty of Science, Hashemite University, P.O. Box 150459, Al-Zarqa 13115 (Jordan)], E-mail: amjadelsheikh3@yahoo.com; Sweileh, Jamal A.; Al-Degs, Yahya S. [Department of Chemistry, Faculty of Science, Hashemite University, P.O. Box 150459, Al-Zarqa 13115 (Jordan)

    2007-12-05

    The effect of dimensions (length and external diameter) of multi-walled carbon nanotubes (MWCNTs) on its preconcentration efficiency towards some metal ions (Pb{sup 2+}, Cd{sup 2+}, Cu{sup 2+}, Zn{sup 2+} and MnO{sub 4}{sup -}) from environmental waters prior to their analysis by flame atomic absorption spectroscopy (FAAS) was investigated. MWCNTs (as-received from the manufacturer) of various external diameters and lengths were involved. Other variables optimized included effects of pH of water sample, composition and volume of eluent, mass of the MWCNTs, breakthrough volume and coexisting ions. Maximum recovery of metal ions was obtained at pH 9 where it was thought that precipitation of metals as their hydroxides played the major factor in metals uptake by MWCNT. It was suggested that the use of appropriate dimensions of MWCNTs may support the trapping process of the precipitated metal hydroxides by MWCNTs. It was found that long MWCNT of length 5-15 {mu}m and external diameter 10-30 nm gave the highest enrichment efficiency towards almost all the targeted metal ions. It could be used for preconcentration of MnO{sub 4}{sup -}, Cu{sup 2+}, Zn{sup 2+} and Pb{sup 2+} with almost full recovery; but not for Cd{sup 2+} due to its low recovery. The optimized solid phase extraction (SPE) procedure was capable of determining metal ions in the linear range 20-100 ng mL{sup -1} (except for Zn{sup 2+} from 20 to 150 ng mL{sup -1}). Detection limits were 0.709 ng mL{sup -1} for MnO{sub 4}{sup -}, 0.278 ng mL{sup -1} for Pb{sup 2+}, 0.465 ng mL{sup -1} for Cu{sup 2+}, 0.867 ng mL{sup -1} for Zn{sup 2+}. Application of the optimized SPE procedure to environmental waters (tap water, reservoir water and stream water) gave spike recoveries of the metals in the range of 81-100%.

  1. Strain tunable magnetic properties of 3d transition-metal ion doped monolayer MoS2: A first-principles study

    Science.gov (United States)

    Zhu, Yupeng; Liang, Xiao; Qin, Jun; Deng, Longjiang; Bi, Lei

    2018-05-01

    In this article, a systematic study on the magnetic properties and strain tunability of 3d transition metal ions (Mn, Fe, Co, Ni) doped MoS2 using first-principles calculations is performed. Antiferromagnetic coupling is observed between Mn, Fe ions and the nearest neighbor Mo ions; whereas ferromagnetic coupling is observed in Co and Ni systems. It is also shown that by applying biaxial tensile strain, a significant change of the magnetic moment is observed in all transition metal doped MoS2 materials with a strain threshold. The changes of total magnetic moment have different mechanisms for different doping systems including an abrupt change of the bond lengths, charge transfer and strain induced structural anisotropy. These results demonstrate applying strain as a promising method for tuning the magnetic properties in transition metal ion doped monolayer MoS2.

  2. Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted $^{163}$Ho ions

    CERN Document Server

    Gastaldo, L.; von Seggern, F.; Porst, J.-P.; Schäfer, S.; Pies, C.; Kempf, S.; Wolf, T.; Fleischmann, A.; Enss, C.; Herlert, A.; Johnston, K.

    2013-01-01

    For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of $^{163}$Ho using MMCs having the radioactive $^{163}$Ho ions implanted in the absorber. The implantation of $^{163}$Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. In addition an optimized detector design for future $^{163}$Ho experiments is presented.

  3. Direct trace analysis of metals and alloys in a quadrupole ion-trap mass spectrometer

    CERN Document Server

    Song, K S; Yang, M; Cha, H K; Lee, J M; Lee, G H

    1999-01-01

    An ion-trap mass spectrometer adopting a quadrupole ion-trap and laser ablation/ionization method was constructed. The developed system was tested for composition analysis of some metals (Cu, stainless), and alloys (hastalloy C, mumetal) by mass spectrometry. Samples were analyzed by using laser ablation from a sample probe tip followed by a mass analysis with the quadrupole ion-trap. The quadrupole ion-trap was modified to enable laser ablation by a XeCl excimer laser pulse that passed radially through the ring electrode. A mass scan of the produced ions was performed in the mass selective instability mode wherein trapped ions were successively detected by increasing the rf voltage through the ring electrode. Factors affecting the mass resolution, such as pressure of buffer gas and ablation laser power, are discussed.

  4. Study rationale and protocol: prospective randomized comparison of metal ion concentrations in the patient's plasma after implantation of coated and uncoated total knee prostheses.

    Science.gov (United States)

    Lützner, Jörg; Dinnebier, Gerd; Hartmann, Albrecht; Günther, Klaus-Peter; Kirschner, Stephan

    2009-10-14

    Any metal placed in a biological environment undergoes corrosion. Thus, with their large metallic surfaces, TKA implants are particularly prone to corrosion with subsequent release of metal ions into the human body which may cause local and systemic toxic effects and hypersensitivity reactions, and increase cancer risk. To address this problem, a new 7-layer zirconium coating developed especially for cobalt-chrome orthopaedic implants was tested biomechanically and found to lower metal ion release. The purpose of the proposed clinical trial is to compare the metal ion concentration in patients' plasma before and after implantation of a coated or uncoated TKA implant. In this randomised controlled trial, 120 patients undergoing primary TKA will be recruited at the Department of Orthopaedic Surgery of the University Hospital in Dresden, Germany, and randomised to either the coated or uncoated prosthesis. Outcome assessments will be conducted preoperatively and at 3 months, 12 months and 5 years postoperatively. The primary clinical endpoint will be the chromium ion concentration in the patient's plasma after 1 and 5 years. Secondary outcomes include cobalt, molybdenum and nickel ion concentrations after 1 and 5 years, allergy testing for hypersensitivity against one of these metals, the Knee Society Score to assess clinical and physical function of the knee joint, the self-assessment Oxford Score and the Short Form 36 quality of live questionnaire. The metal ion concentration in the patient's plasma has been shown to increase after TKA, its eventual adverse effects being widely debated. In the light of this discussion, ways to reduce metal ion release from orthopaedic implants should be studied in detail. The results of this investigation may lead to a new method to achieve this goal. TRIALS REGISTER: Clinicaltrials registry NCT00862511.

  5. Study rationale and protocol: prospective randomized comparison of metal ion concentrations in the patient's plasma after implantation of coated and uncoated total knee prostheses

    Directory of Open Access Journals (Sweden)

    Günther Klaus-Peter

    2009-10-01

    Full Text Available Abstract Background Any metal placed in a biological environment undergoes corrosion. Thus, with their large metallic surfaces, TKA implants are particularly prone to corrosion with subsequent release of metal ions into the human body which may cause local and systemic toxic effects and hypersensitivity reactions, and increase cancer risk. To address this problem, a new 7-layer zirconium coating developed especially for cobalt-chrome orthopaedic implants was tested biomechanically and found to lower metal ion release. The purpose of the proposed clinical trial is to compare the metal ion concentration in patients' plasma before and after implantation of a coated or uncoated TKA implant. Methods/Design In this randomised controlled trial, 120 patients undergoing primary TKA will be recruited at the Department of Orthopaedic Surgery of the University Hospital in Dresden, Germany, and randomised to either the coated or uncoated prosthesis. Outcome assessments will be conducted preoperatively and at 3 months, 12 months and 5 years postoperatively. The primary clinical endpoint will be the chromium ion concentration in the patient's plasma after 1 and 5 years. Secondary outcomes include cobalt, molybdenum and nickel ion concentrations after 1 and 5 years, allergy testing for hypersensitivity against one of these metals, the Knee Society Score to assess clinical and physical function of the knee joint, the self-assessment Oxford Score and the Short Form 36 quality of live questionnaire. Discussion The metal ion concentration in the patient's plasma has been shown to increase after TKA, its eventual adverse effects being widely debated. In the light of this discussion, ways to reduce metal ion release from orthopaedic implants should be studied in detail. The results of this investigation may lead to a new method to achieve this goal. Trials register Clinicaltrials registry NCT00862511

  6. Theory Meets Experiment: Metal Ion Effects in HCV Genomic RNA Kissing Complex Formation

    Directory of Open Access Journals (Sweden)

    Li-Zhen Sun

    2017-12-01

    Full Text Available The long-range base pairing between the 5BSL3. 2 and 3′X domains in hepatitis C virus (HCV genomic RNA is essential for viral replication. Experimental evidence points to the critical role of metal ions, especially Mg2+ ions, in the formation of the 5BSL3.2:3′X kissing complex. Furthermore, NMR studies suggested an important ion-dependent conformational switch in the kissing process. However, for a long time, mechanistic understanding of the ion effects for the process has been unclear. Recently, computational modeling based on the Vfold RNA folding model and the partial charge-based tightly bound ion (PCTBI model, in combination with the NMR data, revealed novel physical insights into the role of metal ions in the 5BSL3.2-3′X system. The use of the PCTBI model, which accounts for the ion correlation and fluctuation, gives reliable predictions for the ion-dependent electrostatic free energy landscape and ion-induced population shift of the 5BSL3.2:3′X kissing complex. Furthermore, the predicted ion binding sites offer insights about how ion-RNA interactions shift the conformational equilibrium. The integrated theory-experiment study shows that Mg2+ ions may be essential for HCV viral replication. Moreover, the observed Mg2+-dependent conformational equilibrium may be an adaptive property of the HCV genomic RNA such that the equilibrium is optimized to the intracellular Mg2+ concentration in liver cells for efficient viral replication.

  7. Preorganized and Immobilized Ligands for Metal Ion Separations

    Energy Technology Data Exchange (ETDEWEB)

    Paine, Robert T. [Univ. of New Mexico, Albuquerque, NM (United States)

    2015-07-01

    The research project, in the period 2003-2015, was focused on the discovery of fundamental new principles in f-element ion coordination chemistry and the application of the new knowledge to the development of advanced detection/separations reagents and methods for these ions. The findings relate to the Nation's efforts to safely and efficiently process nuclear materials. In addition, the project provided training for young scientists needed to maintain the Nation's preeminence in nuclear science.

  8. Responses of a soil bacterium, Pseudomonas chlororaphis O6 to commercial metal oxide nanoparticles compared with responses to metal ions

    International Nuclear Information System (INIS)

    Dimkpa, Christian O.; Calder, Alyssa; Britt, David W.; McLean, Joan E.; Anderson, Anne J.

    2011-01-01

    The toxicity of commercially-available CuO and ZnO nanoparticles (NPs) to pathogenic bacteria was compared for a beneficial rhizosphere isolate, Pseudomonas chlororaphis O6. The NPs aggregated, released ions to different extents under the conditions used for bacterial exposure, and associated with bacterial cell surface. Bacterial surface charge was neutralized by NPs, dependent on pH. The CuO NPs were more toxic than the ZnO NPs. The negative surface charge on colloids of extracellular polymeric substances (EPS) was reduced by Cu ions but not by CuO NPs; the EPS protected cells from CuO NPs-toxicity. CuO NPs-toxicity was eliminated by a Cu ion chelator, suggesting that ion release was involved. Neither NPs released alkaline phosphatase from the cells' periplasm, indicating minimal outer membrane damage. Accumulation of intracellular reactive oxygen species was correlated with CuO NPs lethality. Environmental deposition of NPs could create niches for ion release, with impacts on susceptible soil microbes. - Highlights: → Toxicity of metallic nanoparticles (NPs) was evaluated in a beneficial bacterium, Pseudomonas chlororaphis O6 (PcO6). → Aggregated commercial CuO and ZnO NPs released Cu and Zn ions and changed bacterial surface charge, depending on pH. → The NPs were toxic to PcO6 through NP-specific, but also ion release mechanisms. → Reactive oxygen species were produced by CuO NP and Cu ion at lethal concentrations, but bacterial EPS protected against Cu. → The periplasmic marker, alkaline phosphate, activity was increased by the NPs and ions. - Aggregated CuO and ZnO nanoparticles release ions and cause different toxicities in a beneficial soil bacterium.

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

    Directory of Open Access Journals (Sweden)

    Jörg Friesenbichler

    2014-01-01

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

  10. Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies

    Science.gov (United States)

    Vinod Kumar, V.; Anbarasan, S.; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

    2014-08-01

    Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg2+, Cd2+ and Pb2+ metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

  11. Design dopamine-modified polypropylene fibers towards removal of heavy metal ions from water

    Directory of Open Access Journals (Sweden)

    K. Liu

    2017-04-01

    Full Text Available A simple approach to preparing dopamine-modified polypropylene fibers with a controllable polydopamine amount is supplied. By the dopamine modification, the hydrophobic polypropylene fibers have been changed into hydrophilic. The hydrophilicity can be improved by increasing the amount of polydopamine, as revealed by the contact angle evolutions. The hydrophilic dopamine-modified polypropylene fibers can rapidly and effectively remove copper and lead ions in water. Moreover, the performance of removing heavy metals is prominently improved as the polydopamine amount increases. This is because the polydopamine introduction can supply many available sites for adsorbing heavy metal ions, as revealed by theoretical simulation results. These results are crucial in future engineering fiber filters towards efficiently removing heavy metal ions using dopamine-modified polypropylene fibers.

  12. Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Karsten, W.E.; Harris, B.G.; Cook, P.F. (Texas College of Osteopathic Medicine, Fort Worth (United States))

    1992-01-01

    The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined [sup 13]C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzyme catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer.

  13. Separation of some metal ions using coupled transport supported liquid membranes

    International Nuclear Information System (INIS)

    Chaudhary, M.A.

    1993-01-01

    Liquid membrane extraction processes has become very popular due to their superiority in many ways over other separation techniques. In coupled transport membranes the metal ions can be transported across the membrane against their concentration gradient under the influence of chemical potential difference. Liquid membranes consisting of a carrier-cum-diluent, supported in microporous polymeric hydrophobic films have been studied for transport of metal ions like U(VI), Cr(VI), Be(II), V(V), Ti(IV), Zn(II), Cd(II), Hf(IV), W(VI), and Co(II). The present paper presents basic data with respect to flux and permeabilities of these metal ions across membranes based on experimental results and theoretical equations, using different carriers and diluents and provides a brief reference to possibility of such membranes for large scale applications. (author)

  14. Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae.

    Science.gov (United States)

    Begg, Stephanie L; Eijkelkamp, Bart A; Luo, Zhenyao; Couñago, Rafael M; Morey, Jacqueline R; Maher, Megan J; Ong, Cheryl-Lynn Y; McEwan, Alastair G; Kobe, Bostjan; O'Mara, Megan L; Paton, James C; McDevitt, Christopher A

    2015-03-03

    Cadmium is a transition metal ion that is highly toxic in biological systems. Although relatively rare in the Earth's crust, anthropogenic release of cadmium since industrialization has increased biogeochemical cycling and the abundance of the ion in the biosphere. Despite this, the molecular basis of its toxicity remains unclear. Here we combine metal-accumulation assays, high-resolution structural data and biochemical analyses to show that cadmium toxicity, in Streptococcus pneumoniae, occurs via perturbation of first row transition metal ion homeostasis. We show that cadmium uptake reduces the millimolar cellular accumulation of manganese and zinc, and thereby increases sensitivity to oxidative stress. Despite this, high cellular concentrations of cadmium (~17 mM) are tolerated, with negligible impact on growth or sensitivity to oxidative stress, when manganese and glutathione are abundant. Collectively, this work provides insight into the molecular basis of cadmium toxicity in prokaryotes, and the connection between cadmium accumulation and oxidative stress.

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

    International Nuclear Information System (INIS)

    Karsten, W.E.; Harris, B.G.; Cook, P.F.

    1992-01-01

    The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined 13 C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzyme catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer

  17. Off-line production of transition-metal ions at BECOLA

    Science.gov (United States)

    Ryder, Caleb; Asberry, Hillary; Harris, Justin; Mantica, Paul; Minamisono, Kei; Rossi, Dominic; Strum, Ryan; Smith, April

    2014-09-01

    Collinear laser spectroscopy (CLS) of stable reference beams produced using off-line methods is critical in CLS experiments for calibrating the beam energy during experimental runs, developing atomic laser excitation schemes and reliably deducing nuclear properties from hyperfine spectra collected from on-line beams of radioisotopes. The BEam COoler and LAser Spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University employs several ion sources for off-line stable beam production, each specializing in ion generation from specific materials. The focus of this talk will be on the Penning Ionization Gauge (PIG) ion source, a plasma sputtering source that has been recently implemented at BECOLA to readily produce transition metal ion beams. Collinear laser spectroscopy (CLS) of stable reference beams produced using off-line methods is critical in CLS experiments for calibrating the beam energy during experimental runs, developing atomic laser excitation schemes and reliably deducing nuclear properties from hyperfine spectra collected from on-line beams of radioisotopes. The BEam COoler and LAser Spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University employs several ion sources for off-line stable beam production, each specializing in ion generation from specific materials. The focus of this talk will be on the Penning Ionization Gauge (PIG) ion source, a plasma sputtering source that has been recently implemented at BECOLA to readily produce transition metal ion beams. This work was supported in part by NSF Grant No. PHY-11-02511.

  18. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrations in an urban estuary.

    Science.gov (United States)

    Dong, Zhao; Lewis, Christopher G; Burgess, Robert M; Coull, Brent; Shine, James P

    2016-05-01

    Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limited, due to underexplored techniques for measuring multiple free metal ions simultaneously. In this work, we performed statistical analyses on a large dataset containing repeated measurements of free ion concentrations of Cu, Zn, Pb, Ni, and Cd, the most commonly measured metals in seawater, at five inshore locations in Boston Harbor, previously collected using an in-situ equilibrium-based multi-metal free ion sampler, the 'Gellyfish'. We examined correlations among these five metals by season, and evaluated effects of 10 biogeochemical variables on free ion concentrations over time and location through multivariate regressions. We also explored potential clustering among the five metals through a principal component analysis. We found significant correlations among metals, with varying patterns over season. Our regression results suggest that instead of dissolved metals, pH, salinity, temperature and rainfall were the most significant determinants of free metal ion concentrations. For example, a one-unit decrease in pH was associated with a 2.2 (Cd) to 99 (Cu) times increase in free ion concentrations. This work is among the first to reveal key contributors to spatiotemporal variations in free ion concentrations, and demonstrated the usefulness of the Gellyfish sampler in routine sampling of free ions within metal mixtures and in generating data for statistical analyses. Copyright © 2016. Published by Elsevier Ltd.

  19. Thermoelectric material including a multiple transition metal-doped type I clathrate crystal structure

    Science.gov (United States)

    Yang, Jihui [Lakeshore, CA; Shi, Xun [Troy, MI; Bai, Shengqiang [Shanghai, CN; Zhang, Wenqing [Shanghai, CN; Chen, Lidong [Shanghai, CN; Yang, Jiong [Shanghai, CN

    2012-01-17

    A thermoelectric material includes a multiple transition metal-doped type I clathrate crystal structure having the formula A.sub.8TM.sub.y.sub.1.sup.1TM.sub.y.sub.2.sup.2 . . . TM.sub.y.sub.n.sup.nM.sub.zX.sub.46-y.sub.1.sub.-y.sub.2.sub.- . . . -y.sub.n.sub.-z. In the formula, A is selected from the group consisting of barium, strontium, and europium; X is selected from the group consisting of silicon, germanium, and tin; M is selected from the group consisting of aluminum, gallium, and indium; TM.sup.1, TM.sup.2, and TM.sup.n are independently selected from the group consisting of 3d, 4d, and 5d transition metals; and y.sub.1, y.sub.2, y.sub.n and Z are actual compositions of TM.sup.1, TM.sup.2, TM.sup.n, and M, respectively. The actual compositions are based upon nominal compositions derived from the following equation: z=8q.sub.A-|.DELTA.q.sub.1|y.sub.1-|.DELTA.q.sub.2|y.sub.2- . . . -|.DELTA.q.sub.n|y.sub.n, wherein q.sub.A is a charge state of A, and wherein .DELTA.q.sub.1, .DELTA.q.sub.2, .DELTA.q.sub.n are, respectively, the nominal charge state of the first, second, and n-th TM.

  20. Including sheath effects in the interpretation of planar retarding potential analyzer's low-energy ion data.

    Science.gov (United States)

    Fisher, L E; Lynch, K A; Fernandes, P A; Bekkeng, T A; Moen, J; Zettergren, M; Miceli, R J; Powell, S; Lessard, M R; Horak, P

    2016-04-01

    The interpretation of planar retarding potential analyzers (RPA) during ionospheric sounding rocket missions requires modeling the thick 3D plasma sheath. This paper overviews the theory of RPAs with an emphasis placed on the impact of the sheath on current-voltage (I-V) curves. It then describes the Petite Ion Probe (PIP) which has been designed to function in this difficult regime. The data analysis procedure for this instrument is discussed in detail. Data analysis begins by modeling the sheath with the Spacecraft Plasma Interaction System (SPIS), a particle-in-cell code. Test particles are traced through the sheath and detector to determine the detector's response. A training set is constructed from these simulated curves for a support vector regression analysis which relates the properties of the I-V curve to the properties of the plasma. The first in situ use of the PIPs occurred during the MICA sounding rocket mission which launched from Poker Flat, Alaska in February of 2012. These data are presented as a case study, providing valuable cross-instrument comparisons. A heritage top-hat thermal ion electrostatic analyzer, called the HT, and a multi-needle Langmuir probe have been used to validate both the PIPs and the data analysis method. Compared to the HT, the PIP ion temperature measurements agree with a root-mean-square error of 0.023 eV. These two instruments agree on the parallel-to-B plasma flow velocity with a root-mean-square error of 130 m/s. The PIP with its field of view aligned perpendicular-to-B provided a density measurement with an 11% error compared to the multi-needle Langmuir Probe. Higher error in the other PIP's density measurement is likely due to simplifications in the SPIS model geometry.