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Sample records for earth metal ions

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

    NASA Astrophysics Data System (ADS)

    Gacesa, Marko; Côté, Robin

    2015-05-01

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

  2. Magic wavelengths in the alkaline-earth-metal ions

    NASA Astrophysics Data System (ADS)

    Kaur, Jasmeet; Singh, Sukhjit; Arora, Bindiya; Sahoo, B. K.

    2015-09-01

    We present magic wavelengths for the n S1 /2-n P1 /2 ,3 /2 , and n S1 /2-m D3 /2 ,5 /2 transitions in Mg+, Ca+, Sr+, and Ba+ alkaline-earth-metal ions, for the principal quantum numbers n and m for the ground and first excited D states, respectively. These wavelengths are presented for linearly polarized light by plotting the dynamic polarizabilities of the n S ,n P1 /2 ,3 /2 , and m D3 /2 ,5 /2 states of the considered ions. Required dynamic polarizabilities are evaluated by employing a relativistic all-order perturbative method and their accuracies are ratified by comparing their static values with available high-precision experimental or other theoretical results. Moreover, some of the magic wavelengths identified by us in Ca+ concur with the recent measurements reported by Liu et al. [Phys. Rev. Lett. 114, 223001 (2015), 10.1103/PhysRevLett.114.223001]. Knowledge of these magic wavelengths is propitious to carry out many proposed high-precision measurements trapping the above ions in electric fields with the corresponding frequencies.

  3. Efficient qubit detection using alkaline-earth-metal ions and a double stimulated Raman adiabatic process

    SciTech Connect

    Moeller, Ditte; Soerensen, Jens L.; Thomsen, Jakob B.; Drewsen, Michael

    2007-12-15

    We present a scheme for robust and efficient projection measurement of a qubit consisting of the two magnetic sublevels in the electronic ground state of alkaline-earth-metal ions. The scheme is based on two stimulated Raman adiabatic passages involving four partially coherent laser fields. We show how the efficiency depends on experimentally relevant parameters: Rabi frequencies, pulse widths, laser linewidths, one- and two-photon detunings, residual laser power, laser polarization, and ion motion.

  4. Alkaline Earth Metal Ion/Dihydroxy-Terephthalate MOFs: Structural Diversity and Unusual Luminescent Properties.

    PubMed

    Douvali, Antigoni; Papaefstathiou, Giannis S; Gullo, Maria Pia; Barbieri, Andrea; Tsipis, Athanassios C; Malliakas, Christos D; Kanatzidis, Mercouri G; Papadas, Ioannis; Armatas, Gerasimos S; Hatzidimitriou, Antonios G; Lazarides, Theodore; Manos, Manolis J

    2015-06-15

    Alkaline earth (group 2) metal ion organic frameworks (AEMOFs) represent an important subcategory of MOFs with interesting structures and physical properties. Five MOFs, namely, [Mg2(H2dhtp)2(?-H2O)(NMP)4] (AEMOF-2), [Mg2(H2dhtp)1.5(DMAc)4]Cl·DMAc (AEMOF-3), [Ca(H2dhtp)(DMAc)2] (AEMOF-4), [Sr3(H2dhtp)3(DMAc)6]·H2O (AEMOF-5), and [Ba(H2dhtp)(DMAc)] (AEMOF-6) (H4dhtp = 2,5-dihydroxy-terepthalic acid; DMAc = N,N-dimethylacetamide; NMP = N-methylpyrrolidone), are presented herein. The reported MOFs display structural variety with diverse topologies and new structural features. Interestingly, AEMOF-6 is the first example of a Ba(2+)-H2dhtp(2-) MOF, and AEMOF-5 is only the second known Sr(2+)-H2dhtp(2-) MOF. Detailed photoluminescence studies revealed alkaline earth metal ion-dependent fluorescence properties of the materials, with the heavier alkaline earth metal ions exhibiting red-shifted emission with respect to the lighter ions at room temperature. A bathochromic shift of the emission was observed for the MOFs (mostly for AEMOF-3 and AEMOF-4) at 77 K as a result of excited state proton transfer (ESIPT), which involves an intramolecular proton transfer from a hydroxyl to an adjacent carboxylic group of the H2dhtp(2-) ligand. Remarkably, AEMOF-6 displays rare yellow fluorescence at room temperature, which is attractive for solid state lighting applications. To probe whether the alkaline earth metal ions are responsible for the unusual luminescence properties of the reported MOFs, the potential energy surfaces (PESs) of the ground, S0, and lowest energy excited singlet, S1, states of model complexes along the intramolecular proton transfer coordinate were calculated by DFT and TD-DFT methods. PMID:26039441

  5. The adsorption kinetics of metal ions onto different microalgae and siliceous earth.

    PubMed

    Schmitt, D; Müller, A; Csögör, Z; Frimmel, F H; Posten, C

    2001-03-01

    In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper, and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus, the brackish water diatom Cyclotella cryptica, the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricornutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation. PMID:11228977

  6. Demonstrating the possibility of implementing the Toffoli gate in crystals doped by rare-earth metal ions

    NASA Astrophysics Data System (ADS)

    Akhmedzhanov, R. A.; Gushchin, L. A.; Zelensky, I. V.; Malakyan, Yu. P.; Sobgaida, D. A.

    2015-07-01

    A scheme for the implementation of the Toffoli gate in inorganic crystals doped by rare-earth metal ions is proposed. A numerical analysis of the factors affecting the fidelity of the Toffoli gate implementation is carried out, and estimates for the available experimental parameters are obtained. A demonstration experiment is set up in which behavior similar to the Toffoli gate is shown for ensembles of Pr3+ ions doped into a LaF3 crystal.

  7. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    NASA Astrophysics Data System (ADS)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  8. Rare-earth neutral metal injection into an electron beam ion trap plasma

    SciTech Connect

    Magee, E. W. Beiersdorfer, P.; Brown, G. V.; Hell, N.

    2014-11-15

    We have designed and implemented a neutral metal vapor injector on the SuperEBIT high-energy electron beam ion trap at the Lawrence Livermore National Laboratory. A horizontally directed vapor of a europium metal is created using a thermal evaporation technique. The metal vapor is then spatially collimated prior to injection into the trap. The source's form and quantity constraints are significantly reduced making plasmas out of metal with vapor pressures ?10{sup ?7} Torr at ?1000?°C more obtainable. A long pulsed or constant feed metal vapor injection method adds new flexibility by varying the timing of injection and rate of material being introduced into the trap.

  9. Radiation-enhanced thermal diffusion of transition metal and rare earth ions into II-VI semiconductors

    NASA Astrophysics Data System (ADS)

    Martinez, Alán.; Williams, Lamario; Gafarov, Ozarfar; Martyshkin, Dmitry; Fedorov, Vladimir; Mirov, Sergey

    2015-02-01

    We report on study of gamma radiation-enhanced thermal diffusion of Transition Metal and Rare Earth ions into IIVI semiconductor crystals. ZnSe and ZnS samples with of iron thin film deposited on one facet were sealed in evacuated quartz ampoules at 10-3 Torr. The crystals were annealed for 14 days at 950°C under ?-irradiation from 60Co source. The irradiation dose rates of 43.99 R/s, 1.81 R/s were varied by distance between 60Co source and furnaces. For comparison, the samples were also annealed without irradiation at the same temperature. The spatial distributions of transition metal were measured by absorption of focused laser radiation at 5T2-5E mid-IR transitions of iron ions. In addition, samples of ZnSe were similarly sealed in evacuated quartz ampoules in the presence of Praseodymium metal and annealed at 950°C under 43.99 R/s and 0 R/s and the diffusion lengths and Pr concentrations were compared. The ?-irradiation results in better intrusion of the iron ions from the metal film and increase of the diffusion length at ~25%, while Praseodymium diffusion is dramatically enhanced by ?-irradiation during the annealing process.

  10. Radiative properties of few F- and Cl- like alkali and alkaline-earth metal ions

    NASA Astrophysics Data System (ADS)

    Nandy, D. K.; Singh, Sukhjit; Sahoo, B. K.

    2015-09-01

    We present high-accuracy calculations of radiative properties such as oscillator strengths and transition probabilities, of the allowed ns 2S1/2 ? np 2P1/2, 3/2 transitions and of the forbidden np 2P1/2 ? np 2P3/2 transitions in the F- and Cl-like alkali and alkaline-earth ions with the ground state principal quantum number n of the respective ion. For this purpose, we have employed the Dirac-Fock, relativistic second-order many-body perturbation theory and an all-order perturbative relativistic method in the coupled-cluster (CC) theory framework. To test the validity of these methods for giving accurate results, we first evaluated the ionization potentials in the creation processes of these ions and compare them with their experimental values listed in the National Institute of Science and Technology data base. Moreover, both the allowed and forbidden transition amplitudes are estimated using the above three methods and a comparative analysis is made to follow-up the electron correlation trends in order to demonstrate the need of using a sophisticated method like the CC theory for their precise determination. For astrophysical use, we provide the most precise values of the transition properties by combining the experimental energies, which suppresses uncertainties from the calculated energies, using the transition amplitudes from the CC method. These data will be useful in the abundance analysis of the considered ions in the astronomical objects and for the diagnostic processes of astrophysical plasmas.

  11. Dispersion coefficients for the interactions of the alkali-metal and alkaline-earth-metal ions and inert-gas atoms with a graphene layer

    NASA Astrophysics Data System (ADS)

    Kaur, Kiranpreet; Arora, Bindiya; Sahoo, B. K.

    2015-09-01

    Largely motivated by a number of applications, the van der Waals dispersion coefficients C3 of the alkali-metal ions Li+,Na+,K+, and Rb+, the alkaline-earth-metal ions Ca+,Sr+,Ba+, and Ra+, and the inert-gas atoms He, Ne, Ar, and Kr with a graphene layer are determined precisely within the framework of the Dirac model. For these calculations, we evaluate the dynamic polarizabilities of the above atomic systems very accurately by evaluating the transition matrix elements employing relativistic many-body methods and using the experimental values of the excitation energies. The dispersion coefficients are given as functions of the separation distance of an atomic system from the graphene layer and the ambiance temperature during the interactions. For easy extraction of these coefficients, we give a logistic fit to the functional forms of the dispersion coefficients in terms of the separation distances at room temperature.

  12. Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates

    NASA Astrophysics Data System (ADS)

    Narayan, Himanshu; Alemu, Hailemichael; Nketsa, Pusetso F.; Manatha, Toka J.; Madhavi Thakurdesai, And

    2015-05-01

    Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe(CN)6 · 3H2 O [with, R?Y, Gd and Yb] nanoparticles were synthesized through precipitation. Characterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive PMMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single-crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe(CN)6 · 3H2 O nanoparticles is being reported for the very first time.

  13. Mutual influence of trivalent rare-earth metal ions at their extraction from nitrate solutions by mixtures of tributyl phosphate and diisooctyl methylphosphonate

    SciTech Connect

    Pyartman, A.K.; Puzikov, E.A.; Kopyrin, A.A.

    1995-01-01

    Extraction of yttrium-group lanthanide(III) and yttrium nitrates from multicomponent solutions by mixtures of tri-n-butyl phosphate and diisooctyl methylphosphonate has been examined at 298.15 K and pH 2. A physiocochemical and mathematical model has been developed to describe distribution and mutual influence of rare-earth metal ions in multicomponent solutions as influenced by the total concentration of rare-earth metals in aqueous phase and compositions of the concentrate and of organic phase.

  14. Extractive properties towards rare-earth metal ions of calix[4]arenes substituted at the narrow rim by phosphoryl and amide groups

    SciTech Connect

    Yaftian, M.R.; Burgard, M.; Wieser, C.; Dieleman, C.B.; Matt, D.

    1998-08-01

    The extractive properties of the cone and partial-cone isomers of 5,11,17,23-tetra-tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-bis(diphenylphosphinoylmethoxy)calix[4]arene (cone-1 and partial-cone-1) in 1,2-dichloroethane towards rare-earth metal ions in nitrate media at 25 C were investigated. The analysis of the extraction equilibrium obtained from a mixture of four rare-earths (La, Eu, Er and Y) revealed that the extracted species have a 1:1 metal/ligand ratio for both ligands. The intra-group separation efficiencies of the ligands have been evaluated in a competitive extraction process of 11 rare-earth metal ions (La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Y). Significantly higher extractive properties were found for cone-1 with respect to partial-cone-1, suggesting the crucial role of the phosphoryl groups in the complexation of the rare-earth ions.

  15. Parity nonconservation in Fr-like actinide and Cs-like rare-earth-metal ions

    NASA Astrophysics Data System (ADS)

    Roberts, B. M.; Dzuba, V. A.; Flambaum, V. V.

    2013-07-01

    Parity-nonconservation (PNC) amplitudes are calculated for the 7s-6d3/2 transitions of the francium isoelectronic sequence (Fr, Ra+, Ac2+, Th3+, Pa4+, U5+, and Np6+) and for the 6s-5d3/2 transitions of the cesium isoelectronic sequence (Cs, Ba+, La2+, Ce3+, and Pr4+). We show in particular that isotopes of La2+, Ac2+, and Th3+ ions have strong potential in the search for new physics beyond the standard model: The PNC amplitudes are large, the calculations are accurate, and the nuclei are practically stable. In addition, 232Th3+ ions have recently been trapped and cooled [Campbell , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.102.233004 102, 233004 (2009)]. We also extend previous works by calculating the s-s PNC transitions in Ra+ and Ba+ and provide calculations of several energy levels, and electric dipole and quadrupole transition amplitudes for the Fr-like actinide ions.

  16. Chelation ion chromatography of alkaline earth and transition metals a using monolithic silica column with bonded N-hydroxyethyliminodiacetic acid functional groups.

    PubMed

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Jones, Phil; Paull, Brett

    2013-02-01

    A commercially available porous silica monolithic column (Onyx Monolithic Si, 100 mm×4.6 mm I.D.) was 'in-column' covalently functionalised with 2-hydroxyethyliminodiacetic acid (HEIDA) groups, and applied to the simultaneous and rapid separation of alkaline earth and transition metal ions, using high-performance chelation ion chromatography (HPCIC). With a 0.3mM dipicolinic acid (DPA) containing eluent, the baseline separation of various common transition and heavy metal ions and the four alkaline earth metal ions could be achieved in under 14 min with a flow rate of just 0.8 mL/min. Detection was achieved using spectrophotometric detection at 540 nm after post-column reaction (PCR) with 4-(2-pyridylazo)-resorcinol (PAR). Significant effects from variation of eluent nature, concentration and temperature upon selectivity and retention were demonstrated with the new monolithic silica chelating phase. Under optimised conditions (0.165 M LiNO(3) eluent, pH 2.5), peak efficiencies of 54,000, 60,000 and 64,000 N/m, for Zn(2+), Mn(2+) and Cd(2+), respectively, were recorded, far exceeding that previously reported for IDA based chelation ion exchange columns. PMID:23298846

  17. Metal Ion Sources for Ion Beam Implantation

    SciTech Connect

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

    2008-11-03

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

  18. Reactivity and Infrared Spectroscopy of Gaseous Hydrated Trivalent Metal Ions

    E-print Network

    Cohen, Ronald C.

    trivalent rare earth metal ions containing yttrium and all naturally abundant lanthanide metals are formedReactivity and Infrared Spectroscopy of Gaseous Hydrated Trivalent Metal Ions Matthew F. Bush sizes that differs by only a few water molecules for each metal ion. The effective turnover size

  19. Adsorption of humic acid by bi-functional resin JN-10 and the effect of alkali-earth metal ions on the adsorption.

    PubMed

    Wang, Jinnan; Zhou, Yang; Li, Aimin; Xu, Li

    2010-04-15

    This study investigated the adsorption of humic acid (HA) by bi-functional resin JN-10, which removed the HA more effectively than the commercial resins D-301, D-201, XAD-7, and globe active carbon F-400. The difference between the FT-IR spectroscopy and (13)C NMR analysis of JN-10 before and after it adsorbing the HA revealed that both hydrophobic interaction and electric attraction were the adsorption force for the HA. The related thermodynamic parameters exhibited that the adsorption of the HA by JN-10 was an endothermic process. The occurring of adsorption was due to the increase of entropy, and the electric attraction was also a main adsorption force. In order to investigate the influence of the molecule weight (MW) of the HA on its removal by JN-10, the HA with the MWs ranging from 2000 to 100,000 Da was divided into six fractions by ultra-filtration. The HA with a medium MW (6000-10,000 Da) was preferentially removed by JN-10 due to the synergistic effect of hydrophilicity, molecular size, and aromaticity of the HA. The adsorption capacity of JN-10 for the HA increased in the presence of low concentration of alkali-earth metal ions Ca(2+) and Mg(2+), which neutralized the negative charges of the HA, but it decreased as the concentration of these ions increased because the hydrates formed by the alkali-earth metal ions occupied the adsorption sites of the resin. PMID:20074851

  20. Bioavailability of Metal Ions and Evolutionary Adaptation

    PubMed Central

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

    2012-01-01

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

  1. Metal Ions in Neuroscience

    PubMed Central

    Ragan, C. Ian

    1997-01-01

    Metal ions are believed to participate in many neurodegenerative conditions. In excitotoxic cell death there is convincing evidence for the participation of Ca2+ and Zn2+ ions although the exact molecular mechanisms by which these metals exert their effects are unclear. Only in one instance has the metal binding site of metalloenzymes been exploited for therapeutic purposes and this is the use of Li+ in the treatment of bipolar affective disorder. Again the exact molecular target is not clear but is likely to involve a Mg2+-dependent enzyme of an intracellular signalling pathway. In Parkinson's disease, the selective loss of dopaminergic neurones in the substantia nigra may be caused by radical-mediated damage and there is good evidence to suggest that Fe2+ or 3+ is important in promoting formation of radical species. The evidence that free radicals are important in mediating other neurodegenerative conditions is less strong but still substantial enough to suggest that removal of reactive oxygen species or preventing their formation may be a valid approach to therapy. PMID:18475782

  2. {sup 1}H and {sup 23}Na MAS NMR spectroscopy of cationic species in CO{sub 2} selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    SciTech Connect

    Arevalo-Hidalgo, Ana G.; Dugar, Sneha; Fu, Riqiang; Hernandez-Maldonado, Arturo J.

    2012-07-15

    The location of extraframework cations in Sr{sup 2+} and Ba{sup 2+} ion-exchanged SAPO-34 was estimated by means of {sup 1}H and {sup 23}Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO{sub 2} adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO{sub 2} adsorption performance. Highlights: Black-Right-Pointing-Pointer Location of extraframework Sr{sup 2+} or Ba{sup 2+} cations was estimated by means of {sup 1}H and {sup 23}Na MAS NMR. Black-Right-Pointing-Pointer Level of Sr{sup 2+} or Ba{sup 2+} ion exchange was limited by the presence of protons and sodium cations. Black-Right-Pointing-Pointer Presence of ammonium cations in the supercages facilitated the exchange. Black-Right-Pointing-Pointer Sr{sup 2+} and Ba{sup 2+} ion exchanged SAPOs are outstanding CO{sub 2} adsorbents.

  3. Synthesis, structural, optical and electrical properties of metal nanoparticle-rare earth ion dispersed in polymer film

    NASA Astrophysics Data System (ADS)

    Kumar, Brijesh; Kaur, Gagandeep; Singh, P.; Rai, S. B.

    2013-03-01

    Cu-nanoparticles have been prepared by ablating a copper target submerged in benzene with laser pulses of Nd:YAG (wavelength: 355, 532 nm and 1,064 nm). Colloidal nanoparticles have been characterized by UV-Vis spectroscopy and transmission electron microscopy. The obtained radius for the nanoparticles prepared using 1,064 nm irradiation lies in the range 15-30 nm, with absorption peak at 572 nm. Luminescence properties of Tb3+ ions in the presence and absence of Cu-nanoparticles have been investigated using 355 nm excitation. An enhancement in luminescence of Tb3+ by local field effect causing increase in lifetime of 5D4 level of Tb3+ ion has been observed. Frequency and temperature-dependent conductivity of Tb3+ doped PVA thin films with and without Cu-nanoparticles have been measured in the frequency range 20 Hz-1 MHz and in the temperature range 318-338 K (well below its melting temperature). Real part of the conductivity spectra has been explained in terms of power law. The electrical properties of the thin films show a decrease in dc conductivity on incorporation of the Cu-nanoparticles.

  4. Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery.

    PubMed

    Yang, D L; Gong, H; Pun, E Y B; Zhao, X; Lin, H

    2010-08-30

    In Er(3+)/Yb(3+) codoped Na(2)O-ZnO-PbO-GeO(2)-TeO(2) (NZPGT) glass fiber, a clear and compact green upconversion amplified spontaneous emission (ASE) trace is observed, and the NZPGT glasses are proved to be a desirable candidate in fabricating low-phonon energy fiber. Intense green upconversion luminescence of Er(3+), balanced green and red upconversion emissions of Ho(3+), and dominant three-photon blue upconversion fluorescence of Tm(3+) have been represented. By varying the excitation power of 974 nm wavelength laser diode, a series of green and white fluorescences have been achieved in Tm(3+)/Er(3+)/Yb(3+) and Tm(3+)/Ho(3+)/Yb(3+) triply doped glass systems, respectively. These results reveal that high-intensity blue, green, and white upconversion ASE fluorescences, which can be adopted for lighting in minimally invasive photodynamic therapy and minimally invasive surgery, are reasonable to be expected in rare-earth doped NZPGT glass fibers. PMID:20940794

  5. Rare Earth Metals: Resourcefulness and Recovery

    NASA Astrophysics Data System (ADS)

    Wang, Shijie

    2013-10-01

    When we appreciate the digital revolution carried over from the twentieth century with mobile communication and the Internet, and when we enjoy our high-tech lifestyle filled with iDevices, hybrid cars, wind turbines, and solar cells in this new century, we should also appreciate that all of these advanced products depend on rare earth metals to function. Although there are only 136,000 tons of annual worldwide demand, (Cho, Rare Earth Metals, Will We Have Enough?)1 rare earth metals are becoming such hot commodities on international markets, due to not only to their increasing uses, including in most critical military hardware, but also to Chinese growth, which accounts for 95% of global rare earth metal production. Hence, the 2013 technical calendar topic, planned by the TMS/Hydrometallurgy and Electrometallurgy Committee, is particularly relevant, with four articles (including this commentary) contributed to the JOM October Issue discussing rare earth metals' resourcefulness and recovery.

  6. Luminescent properties of rare-earth-metal ion-doped KLaNb{sub 2}O{sub 7} with layered perovskite structures

    SciTech Connect

    Kudo, Akihiko

    1997-03-01

    The photochemical properties of layered materials has been extensively studied, but the photochemical properties of two-dimensional oxides of layered compounds has not. This study examined the photoluminescence and thermoluminescence of lanthanide-metal-ion-doped KLaNb{sub 2}O{sub 7} with a layered perovskite structure. 16 refs., 5 figs.

  7. Recycling of rare earth metals from rare earth-transition metal alloy scrap by liquid metal extraction

    DOEpatents

    Ellis, Timothy W. (Ames, IA); Schmidt, Frederick A. (Ames, IA)

    1995-08-01

    Method of treating rare earth metal-bearing scrap, waste or other material (e.g. Nd--Fe--B or Dy--Tb--Fe scrap) to recover the rare earth metal comprising melting the rare earth metal-bearing material, melting a Group IIA metal extractant, such as Mg, Ca, or Ba, in which the rare earth is soluble in the molten state, and contacting the melted material and melted extractant at a temperature and for a time effective to extract the rare earth from the melted material into the melted extractant. The rare earth metal is separated from the extractant metal by vacuum sublimation or distillation.

  8. Recycling of rare earth metals from rare earth-transition metal alloy scrap by liquid metal extraction

    DOEpatents

    Ellis, T.W.; Schmidt, F.A.

    1995-08-01

    A method is described for treating rare earth metal-bearing scrap, waste or other material (e.g. Nd--Fe--B or Dy--Tb--Fe scrap) to recover the rare earth metal comprising melting the rare earth metal-bearing material, melting a Group IIA metal extractant, such as Mg, Ca, or Ba, in which the rare earth is soluble in the molten state, and contacting the melted material and melted extractant at a temperature and for a time effective to extract the rare earth from the melted material into the melted extractant. The rare earth metal is separated from the extractant metal by vacuum sublimation or distillation. 2 figs.

  9. Metal ions in the atmosphere of Neptune.

    PubMed

    Lyons, J R

    1995-02-01

    Microwave propagation experiments performed with Voyager 2 at Neptune revealed sharp layers of electrons in Neptune's lower ionosphere with densities of approximately 10(4) per cubic centimeter. These layers are reminiscent of the sporadic-E layers in the Earth's ionosphere, and when taken together with data from the other giant planets, these data confirm the importance of the magnetic field in layer formation. A photochemical model that incorporates species produced by meteoroid ablation predicts that singly ionized magnesium is the most likely metal to be found in the layers, although laboratory data on the kinetics of metallic atoms and ions in a reducing environment are lacking. The metal chemistry discussed here is directly relevant to the abundant metals observed at the impact site of the G fragment of comet Shoemaker Levy 9 on Jupiter. PMID:7839139

  10. METAL IONS: Physiological function and Pathological rle

    E-print Network

    Morante, Silvia

    METAL IONS: Physiological function and Pathological rôle #12;METAL IONS ARE ESSENTIAL CELL COMPONENTS At least one-third of all proteins encoded in the human genome contain metal ions They can easily of biological processes Their ionization state influences how easily metal can get into cells (e.g.: Fe++ cross

  11. Ion beam modification of metals

    NASA Astrophysics Data System (ADS)

    Dearnaley, G.

    1990-04-01

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

  12. Metal ion-containing epoxies

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  13. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

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

    1983-07-21

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

  14. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G. (Albuquerque, NM); Stephens, Howard P. (Albuquerque, NM); Stohl, Frances V. (Albuquerque, NM)

    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.

  15. Rare-earth-metal nitridophosphates through high-pressure metathesis.

    PubMed

    Kloss, Simon David; Schnick, Wolfgang

    2015-09-14

    Developing a synthetic method to target an broad spectrum of unknown phases can lead to fascinating discoveries. The preparation of the first rare-earth-metal nitridophosphate LiNdP4 N8 is reported. High-pressure solid-state metathesis between LiPN2 and NdF3 was employed to yield a highly crystalline product. The in?situ formed LiF is believed to act both as the thermodynamic driving force and as a flux to aiding single-crystal formation in dimensions suitable for crystal structure analysis. Magnetic properties stemming from Nd(3+) ions were measured by SQUID magnetometry. LiNdP4 N8 serves as a model system for the exploration of rare-earth-metal nitridophosphates that may even be expanded to transition metals. High-pressure metathesis enables the systematic study of these uncharted regions of nitride-based materials with unprecedented properties. PMID:26352033

  16. Mechanistic Enzyme Models: Pyridoxal and Metal Ions.

    ERIC Educational Resources Information Center

    Hamilton, S. E.; And Others

    1984-01-01

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

  17. Binding to Redox-Inactive Alkali and Alkaline Earth Metal Ions Strongly Deactivates the C-H Bonds of Tertiary Amides toward Hydrogen Atom Transfer to Reactive Oxygen Centered Radicals.

    PubMed

    Salamone, Michela; Carboni, Giulia; Mangiacapra, Livia; Bietti, Massimo

    2015-09-18

    The effect of alkali and alkaline earth metal ions on the reactions of the cumyloxyl radical (CumO(•)) with N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) was studied by laser flash photolysis. In acetonitrile, a >2 order of magnitude decrease in the rate constant for hydrogen atom transfer (HAT) from the C-H bonds of these substrates (kH) was measured after addition of Li(+). This behavior was explained in terms of a strong interaction between Li(+) and the oxygen atom of both DMF and DMA that increases the extent of positive charge on the amide, leading to C-H bond deactivation toward HAT to the electrophilic radical CumO(•). Similar effects were observed after addition of Ca(2+), which was shown to strongly bind up to four equivalents of the amide substrates. With Mg(2+), weak C-H deactivation was observed for the first two substrate equivalents followed by stronger deactivation for two additional equivalents. No C-H deactivation was observed in DMSO after addition of Li(+) and Mg(2+). These results point toward the important role played by metal ion Lewis acidity and solvent Lewis basicity, indicating that C-H deactivation can be modulated by varying the nature of the metal cation and solvent and allowing for careful control over the HAT reactivity of amide substrates. PMID:26322929

  18. Reversible photodeposition and dissolution of metal ions

    DOEpatents

    Foster, Nancy S. (Boulder, CO); Koval, Carl A. (Golden, CO); Noble, Richard D. (Boulder, CO)

    1994-01-01

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

  19. Metallic ions in the equatorial ionosphere

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  20. Synthesis, characterization and cytotoxicity of rare earth metal ion complexes of N,N?-bis-(2-thiophenecarboxaldimine)-3,3?-diaminobenzidene, Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Abbasi, Ambreen; Faraz, Mohammad; Sherwani, Asif

    2015-12-01

    Lanthanide complexes of La3+, Pr3+, Nd3+, Gd3+, Er3+ of general formula [Ln2 L(H2O)4(NO3)4](NO3)2·2H2O have been synthesized from Schiff base, N,N?-bis-(2-thiophenecarboxaldimine)-3,3?-diaminobenzidene. The complexes were characterized by elemental analysis, molar conductance, UV-Vis, fluorescence, FT-IR,1H NMR, mass spectroscopy, EDX, SEM and thermal analysis. FT-IR spectral data suggested that ligand coordinate with metal ions through azomethine nitrogen and uncondensed amino group. Molar conductance data revealed 1:2 electrolytic nature of complexes. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (ligand:metal). Thephysico-chemical data suggested eight coordination number for Ln(III)Schiffbase complexes. SEM analysis shows morphological changes in the surfaces of complexes as compared to free ligand. Thermal decomposition profiles were consistent with proposed formulations. The anticancer activity of the complexes and theSchiffbase ligand has been studied towards human cervical cancer celllines (HeLa) and human breast cancer cell lines (MCF-7) and it was found that complexes exhibited greater activity than theSchiffbase.

  1. Impulsive ion acceleration in earth's outer magnetosphere

    SciTech Connect

    Baker, D.N.; Belian, R.D.

    1985-01-01

    Considerable observational evidence is found that ions are accelerated to high energies in the outer magnetosphere during geomagnetic disturbances. The acceleration often appears to be quite impulsive causing temporally brief (10's of seconds), very intense bursts of ions in the distant plasma sheet as well as in the near-tail region. These ion bursts extend in energy from 10's of keV to over 1 MeV and are closely associated with substorm expansive phase onsets. Although the very energetic ions are not of dominant importance for magnetotail plasma dynamics, they serve as an important tracer population. Their absolute intensity and brief temporal appearance bespeaks a strong and rapid acceleration process in the near-tail, very probably involving large induced electric fields substantially greater than those associated with cross-tail potential drops. Subsequent to their impulsive acceleration, these ions are injected into the outer trapping regions forming ion ''drift echo'' events, as well as streaming tailward away from their acceleration site in the near-earth plasma sheet. Most auroral ion acceleration processes occur (or are greatly enhanced) during the time that these global magnetospheric events are occurring in the magnetotail. A qualitative model relating energetic ion populations to near-tail magnetic reconnection at substorm onset followed by global redistribution is quite successful in explaining the primary observational features. Recent measurements of the elemental composition and charge-states have proven valuable for showing the source (solar wind or ionosphere) of the original plasma population from which the ions were accelerated.

  2. Protein-Transition Metal Ion Networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  3. Liquid metal ion source and alloy

    DOEpatents

    Clark, Jr., William M. (Thousand Oaks, CA); Utlaut, Mark W. (Saugus, CA); Behrens, Robert G. (Los Alamos, NM); Szklarz, Eugene G. (Los Alamos, NM); Storms, Edmund K. (Los Alamos, NM); Santandrea, Robert P. (Santa Fe, NM); Swanson, Lynwood W. (McMinnville, OR)

    1988-10-04

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

  4. Versatile high current metal ion implantation facility

    SciTech Connect

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

    1991-06-01

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

  5. Magic wavelengths in the alkaline earth ions

    E-print Network

    Kaur, Jasmeet; Arora, Bindiya; Sahoo, B K

    2015-01-01

    We present magic wavelengths for the $nS$ - $nP_{1/2,3/2}$ and $nS$ - $mD_{3/2,5/2}$ transitions, with the respective ground and first excited $D$ states principal quantum numbers $n$ and $m$, in the Mg$^+$, Ca$^+$, Sr$^+$ and Ba$^+$ alkaline earth ions for linearly polarized lights by plotting dynamic polarizatbilities of the $nS$, $nP_{1/2,3/2}$ and $mD_{3/2,5/2}$ states of the ions. These dynamic polarizabilities are evaluated by employing a relativistic all-order perturbative method and their accuracies are ratified by comparing their static values with the available high precision experimental or other theoretical results. Moreover, some of the magic wavelengths identified by us in Ca$^+$ concurs with the recent measurements reported in [{\\bf Phys. Rev. Lett. 114, 223001 (2015)}]. Knowledge of these magic wavelengths are propitious to carry out many proposed high precision measurements trapping the above ions in the electric fields with the corresponding frequencies.

  6. COMPUTATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS

    EPA Science Inventory

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

  7. PROTEIN-TRANSITION METAL ION NETWORKS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins obtained from agricultural sources were blended with divalent metal ions. Feather keratin, egg albumin, and wheat gluten had low, medium, and high levels of aspartic and glutamic acid, respectively, and FT-IR showed that the divalent transition metal ions Mn2+, Cu2+, and Zn2+ were tightly ...

  8. Pseudo ribbon metal ion beam source

    SciTech Connect

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

    2014-02-15

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

  9. Separation of metal ions from aqueous solutions

    DOEpatents

    Almon, Amy C. (Augusta, GA)

    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.

  10. Correlations in rare-earth transition-metal permanent magnets

    NASA Astrophysics Data System (ADS)

    Skomski, R.; Manchanda, P.; Kashyap, A.

    2015-05-01

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

  11. Correlations in rare-earth transition-metal permanent magnets

    SciTech Connect

    Skomski, R. Manchanda, P.; Kashyap, A.

    2015-05-07

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo{sub 5}. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA?+?U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

  12. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles

    E-print Network

    Derom, S; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Francs, G Colas des

    2013-01-01

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) are achieved by tuning either the dipolar or quadrupolar particle resonance to the rare earth ions excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  13. Different Adsorption Behavior of Rare Earth and Metallic Ion Complexes on Langmuir Mono layers Probed by Sum-Frequency Generation Spectroscopy

    SciTech Connect

    Song, Woongmo; Vaknin, David; Kim, Doseok

    2013-02-25

    Adsorption behavior of counterions under a Langmuir monolayer was investigated by sum-frequency generation (SFG) spectroscopy. By comparing SFG spectra of arachidic acid (AA) Langmuir monolayer/water interface with and without added salt, it was found that the simple trivalent cation La3+ adsorbed on AA monolayer only when the carboxylic headgroups are charged (deprotonated), implying that counterion adsorption is induced by Coulomb interaction. On the other hand, metal hydroxide complex Fe(OH)3 adsorbed even on a charge-neutral AA monolayer, indicating that the adsorption of iron hydroxide is due to chemical interaction such as covalent or hydrogen bonding to the headgroup of the molecules at the monolayer.

  14. Uptake of metal ions on humic acids

    SciTech Connect

    Pehlivan, E.; Arslan, G.

    2006-09-15

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

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

    SciTech Connect

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

    1993-06-01

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

  16. Liquid metal ion source and alloy

    SciTech Connect

    Clark, W.M. Jr.; Utlaut, M.W.; Storms, E.K.; Behrens, R.G.; Szklarz, E.G.; Swanson, L.W.; Santandrea, R.P.

    1988-10-04

    A liquid metal ion source is described comprising: emission means for emitting positively charged ions of an elemental chemical species; and source means for supplying the species to be emitted to the emission means, the species being supplied in a congruently vaporizing non-eutectic alloy of the elemental chemical species and at least one other element.

  17. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

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

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

    E-print Network

    Das, Rhiju

    Metal-ion rescue revisited: Biochemical detection of site-bound metal ions important for RNA-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules make essential contributions to function. Defining the locations of these site-bound metal ions remains

  19. Metal vapor vacuum arc ion sources

    SciTech Connect

    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.

  20. Liquid metal ion source for cluster ions of metals and alloys: design and characteristics

    NASA Astrophysics Data System (ADS)

    Bhaskar, N. D.; Klimcak, C. M.; Frueholz, R. P.

    1990-01-01

    Currently liquid metal ion sources (LMISs) are of great interest for a wide variety of applications—ion implantation, ion microlithography, thrusters for electric space propulsion, etc. A novel application of the LMIS is for the production of metallic cluster ions. In our laboratory we have designed and optimized the performance of a LMIS for the production of cluster ions of alkali metals. Using liquid rubidium (Rb) we have observed copious production of singly charged cluster ions (Rb+N, N=1-100). As expected the largest fraction of the emission consists of atomic ions. For low source current (<5 ?A) about 80% of the total emission current is that of Rb+. The remaining 20% consists of Rb+2 and Rb+3. However, for large emission currents (>80 ?A) we observe cluster ions as large as Rb+100. We study the mass distribution using the time-of-flight technique.

  1. Intense metal ion beam source for heavy ion fusion

    SciTech Connect

    Brown, I.G.

    1986-05-01

    We have developed an ion source which can produce high current beams of metal ions. The source uses a metal vapor vacuum arc discharge as the plasma medium from which the ions are extracted, so we have called this source the MEVVA ion source. The metal plasma is created simply and efficiently and no carrier gas is required. Beams have been produced from metallic elements spanning the periodic table from lithium through uranium, at extraction voltages from 10 to 60 kV and with beam currents as high as 1.1 Amperes (electrical current in all charge states). A brief description of the source is given and its possible application as an ion source for heavy ion fusion is considered. Beams such as C/sup +/ (greater than or equal to99% of the beam in this species and charge state), Cr/sup 2 +/ (80%), and Ta/sup 3+,4+,5+/ (mixed charge states) have been produced. Beam emittance measurements and ways of increasing the source brightness are discussed.

  2. Computational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Hay, Benjamin P.; Rapko, Brian M.

    2006-06-01

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

  3. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

  4. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

  5. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

  6. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

  7. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

  8. Metal vapor arc ion plating

    DOEpatents

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

    1986-09-09

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

  9. MEVVA ion source for high current metal ion implantation

    SciTech Connect

    Brown, I.; Washburn, J.

    1986-07-01

    The MEVVA (Metal Vapor Vacuum Arc) ion source is a new kind of source which can produce high current beams of metal ions. Beams of a wide range of elements have been produced, spanning the periodic table from lithium up to and including uranium. The source extraction voltage is up to 60 kV, and we are increasing this up to 120 kV. A total ion beam current of over 1 Ampere has been extracted from the present embodiment of the concept, and this is not an inherent limit. The ion charge state distribution varies with cathode material and arc current, and beams like Li/sup +/, Co/sup +,2+,3+/ and U/sup 3+,4+,5+,6+/ for example, are typical; thus the implantation energy can be up to several hundred kilovolts without additional acceleration. The ion source has potential applications for ion implantation and ion beam mixing for achievement of improved corrosion resistance or wear resistance in metals or surface modification of ceramic materials and semiconductors. Here we outline the source and its performance, and describe some very preliminary implantation work using this source.

  10. Rare earth focused ion beam implantation utilizing Er and Pr liquid alloy ion sources

    E-print Network

    Cincinnati, University of

    substrate.17 The success of FIB technology is due to the invention of liquid metal ion sources LMIS .18 A LMIS can be made in needle or capillary form. The liquid metal is drawn into a Taylor cone where ion be used. The liquid metal or liquid alloy should have low vapor pressure and good wettability

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

    SciTech Connect

    Bartsch, Richard A.

    2012-06-04

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

  12. Metal ions affecting the skin and eyes.

    PubMed

    Lansdown, Alan B G

    2011-01-01

    The skin and eyes remain in constant exposure to the surrounding environment and are subject to accidental, occupational, and biological risks at all times, Normal development, homeostasis, and repair following injury depend upon appropriate levels of calcium, zinc, magnesium, copper, iron, and minute amounts of other trace metals. Both tissues exist in a permanent state of dynamic equilibrium with the environment whereby cells lost through natural wear and tear are replaced through genetically regulated mitotic patterns. Normal functional requirements of the constituent tissues depend on critical balances between trace metals, metal ion gradients, and specific carrier proteins which are modulated by upregulation of growth factors, cytokines, hormones, and subcellular regulators acting by autocrine, paracrine, and endocrine mechanisms. Metal ion gradients in epidermal tissues serve critical functions in basal cell proliferation, post-mitotic migration, and functional differentiation in normal homeostasis and in repair following injury. Toxic mechanisms reflect imbalances in trace metals or interaction between xenobiotic and trace metals through competitive binding key carrier proteins and metabolic pathways leading to trace metal imbalances and functional impairment. Alternatively, toxic injuries result through direct cytotoxic action of metal ions on cell membranes, intercellular communication, RNA and DNA damage, and mutagenic change. Arsenic is the only primary carcinogen in the skin following ingestion or topical exposure; beryllium, aluminum, and zirconium are a cause of granuloma. Aluminum as a cause for breast cancer is equivocal. Metal toxicities in the eye result from direct accidental or occupational exposure and systemic uptake of neurotoxic metals and their action on the retina and optic nerve. Calcium, zinc, magnesium, and iron are essential trace elements in eye development and physiology but silver, gold, lead, and mercury are absorbed through optic membranes or from the circulation to accumulate in the vitreous leading to local or systemic action. Lead, mercury, cadmium, aluminum, and other xenobiotic metals are implicated in structural and physiological damage in the mammalian eye. Thallium shows an affinity for melanin. PMID:21473382

  13. Cluster SIMS using metal cluster complex ions

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yukio; Kondou, Kouji; Teranishi, Yoshikazu; Watanabe, Kouji; Nonaka, Hidehiko; Saito, Naoaki; Itoh, Hiroshi; Fujimoto, Toshiyuki; Kurokawa, Akira; Ichimura, Shingo; Tomita, Mitsuhiro

    2008-12-01

    Metal cluster complexes are chemically synthesized organometallic compounds, which have a wide range of chemical compositions with high molecular weight. Using a metal cluster complex ion source, sputtering characteristics of silicon bombarded with normally incident Ir 4(CO) 7+ ions were investigated. Experimental results showed that the sputtering yield at 10 keV was 36, which is higher than that with Ar + ions by a factor of 24. In addition, secondary ion mass spectrometry (SIMS) of boron-delta-doped silicon samples and organic films of poly(methyl methacrylate) (PMMA) was performed. Compared with conventional O 2+ ion beams, Ir 4(CO) 7+ ion beams improved depth resolution by a factor of 2.5 at the same irradiation conditions; the highest depth resolution of 0.9 nm was obtained at 5 keV, 45° with oxygen flooding of 1.3 × 10 -4 Pa. Furthermore, it was confirmed that Ir 4(CO) 7+ ion beams significantly enhanced secondary ion intensity in high-mass region.

  14. Near-Earth asteroids: Metals occurrence, extraction, and fabrication

    NASA Astrophysics Data System (ADS)

    Westfall, Richard

    Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength and resist crack propagation.

  15. Near-Earth asteroids: Metals occurrence, extraction, and fabrication

    NASA Technical Reports Server (NTRS)

    Westfall, Richard

    1991-01-01

    Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength and resist crack propagation.

  16. Novel metal ion surface modification technique

    SciTech Connect

    Brown, I.G.; Godechot, X.; Yu, K.M.

    1990-10-01

    We describe a method for applying metal ions to the near-surface region of solid materials. The added species can be energetically implanted below the surface or built up as a surface film with an atomically mixed interface with the substrate; the metal ion species can be the same as the substrate species or different from it, and more than one kind of metal species can be applied, either simultaneously or sequentially. Surface structures can be fabricated, including coatings and thin films of single metals, tailored alloys, or metallic multilayers, and they can be implanted or added onto the surface and ion beam mixed. We report two simple demonstrations of the method: implantation of yttrium into a silicon substrate at a mean energy of 70 keV and a dose of 1 {times} 10{sup 16} atoms/cm{sup 2}, and the formation of a titanium-yttrium multilayer structure with ion beam mixing to the substrate. 17 refs., 3 figs.

  17. Intense metal-ion-beam production using an impregnated-electrode-type liquid-metal ion source

    NASA Astrophysics Data System (ADS)

    Ishikawa, Junzo; Tsuji, Hiroshi; Aoyama, Yuji; Takagi, Toshinori

    1990-01-01

    The properties of liquid-metal ion sources are very sensitive to their tip structure. Because the impregnated-electrode-type liquid-metal ion source has a porous tip, it generates more than 300-?A ion currents of various metals including relatively high vapor-pressure metals such as Li, Cu, Ga, Ge, Ag, In, and Au, from which ions can be stably extracted. The large beam divergence, a common disadvantage in liquid-metal ion sources, can be overcome by designing new lens systems to efficiently transport the ion beam for both high- and low-energy applications. In addition, the ion beam current can be multiplied by using multiple emission cusps; thus, a germanium ion current of 1.3 mA was obtained by a three-point emission source. Therefore, the impregnated-electrode-type liquid-metal ion source can be utilized as a metal ion source for general applications.

  18. Intense metal-ion-beam production using an impregnated-electrode-type liquid-metal ion source

    SciTech Connect

    Ishikawa, J.; Tsuji, H.; Aoyama, Y.; Takagi, T. )

    1990-01-01

    The properties of liquid-metal ion sources are very sensitive to their tip structure. Because the impregnated-electrode-type liquid-metal ion source has a porous tip, it generates more than 300-{mu}A ion currents of various metals including relatively high vapor-pressure metals such as Li, Cu, Ga, Ge, Ag, In, and Au, from which ions can be stably extracted. The large beam divergence, a common disadvantage in liquid-metal ion sources, can be overcome by designing new lens systems to efficiently transport the ion beam for both high- and low-energy applications. In addition, the ion beam current can be multiplied by using multiple emission cusps; thus, a germanium ion current of 1.3 mA was obtained by a three-point emission source. Therefore, the impregnated-electrode-type liquid-metal ion source can be utilized as a metal ion source for general applications.

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

    E-print Network

    Herschlag, Dan

    elucidation of metal ion interactions with both the enzyme and the substrate(s). In the Tetrahymena group I the ligands of catalytic metal ions within RNA. In applying this strategy to the Tetrahymena group I intron

  20. Material Removes Heavy Metal Ions From Water

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  1. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare... production of rare earth metals and mischmetal by primary rare earth metals facilities......

  2. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare... production of rare earth metals and mischmetal by primary rare earth metals facilities......

  3. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare... production of rare earth metals and mischmetal by primary rare earth metals facilities......

  4. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare... production of rare earth metals and mischmetal by primary rare earth metals facilities......

  5. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare... production of rare earth metals and mischmetal by primary rare earth metals facilities......

  6. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

    PubMed

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-06-15

    The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. PMID:23587931

  7. Solar heavy ion Heinrich fluence spectrum at low earth orbit.

    PubMed

    Croley, D R; Spitale, G C

    1998-01-01

    Solar heavy ions from the JPL Solar Heavy Ion Model have been transported into low earth orbit using the Schulz cutoff criterion for L-shell access by ions of a specific charge to mass ratio. The NASA Brouwer orbit generator was used to get L values along the orbit at 60 second time intervals. Heavy ion fluences of ions 2 < or = Z < or = 92 have been determined for the LET range 1 to 130 MeV-cm2/mg by 60, 120 or 250 mils of aluminum over a period of 24 hours in a 425 km circular orbit inclined 51 degrees. The ion fluence is time dependent in the sense that the position of the spacecraft in the orbit at the flare onset time fixes the relationship between particle flux and spacecraft passage through high L-values where particles have access to the spacecraft. PMID:11542887

  8. High-current pulsed ion source for metallic ions

    SciTech Connect

    Gavin, B.; Abbott, S.; MacGill, R.; Sorensen, R.; Staples, J.; Thatcher, R.

    1981-03-01

    A new sputter-ion PIG source and magnet system, optimized for intermediate charge states, q/A of 0.02 to 0.03, is described. This source will be used with the new Wideroe-based injector for the SuperHILAC. Pulsed electrical currents of several emA of heavy metal ions have been produced in a normalized emittance area of .05..pi.. cm-mr. The source system is comprised of two electrically separate anode chambers, one in operation and one spare, which can be selected by remote control. The entire source head is small and quickly removable.

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

    PubMed

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

    2015-09-15

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

  10. Engineering of microorganisms towards recovery of rare metal ions.

    PubMed

    Kuroda, Kouichi; Ueda, Mitsuyoshi

    2010-06-01

    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. PMID:20393699

  11. Ohmic model for electrodeposition of metallic ions

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  12. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Description of the primary rare earth metals subcategory. 421.270 Section 421...GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270...

  13. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Description of the primary rare earth metals subcategory. 421.270 Section 421...GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270...

  14. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Description of the primary rare earth metals subcategory. 421.270 Section 421...GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270...

  15. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Description of the primary rare earth metals subcategory. 421.270 Section 421...GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270...

  16. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Description of the primary rare earth metals subcategory. 421.270 Section 421...GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270...

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  18. Cold ions in the hot plasma sheet of Earth's magnetotail.

    PubMed

    Seki, Kanako; Hirahara, Masafumi; Hoshino, Masahiro; Terasawa, Toshio; Elphic, Richard C; Saito, Yoshifumi; Mukai, Toshifumi; Hayakawa, Hajime; Kojima, Hirotsugu; Matsumoto, Hiroshi

    2003-04-10

    Most visible matter in the Universe exists as plasma. How this plasma is heated, and especially how the initial non-equilibrium plasma distributions relax to thermal equilibrium (as predicted by Maxwell-Boltzman statistics), is a fundamental question in studies of astrophysical and laboratory plasmas. Astrophysical plasmas are often so tenuous that binary collisions can be ignored, and it is not clear how thermal equilibrium develops for these 'collisionless' plasmas. One example of a collisionless plasma is the Earth's plasma sheet, where thermalized hot plasma with ion temperatures of about 5 x 10(7) K has been observed. Here we report direct observations of a plasma distribution function during a solar eclipse, revealing cold ions in the Earth's plasma sheet in coexistence with thermalized hot ions. This cold component cannot be detected by plasma sensors on satellites that are positively charged in sunlight, but our observations in the Earth's shadow show that the density of the cold ions is comparable to that of hot ions. This high density is difficult to explain within existing theories, as it requires a mechanism that permits half of the source plasma to remain cold upon entry into the hot turbulent plasma sheet. PMID:12686993

  19. Arc discharge ion source for europium and other refractory metals implantation.

    PubMed

    Turek, M; Prucnal, S; Dro?dziel, A; Pyszniak, K

    2009-04-01

    The best method for the impurity doping to the host material is the ion implantation. Due to high melting point of the rare earth standard metal ion sources are useless. One of the solution is to use chemical compounds of rare earths characterized by low melting point. In this paper we describe the novel design of the ion source suitable for refractory metal (e.g., rare earths) ion implantation. The dependencies of Eu(+) current on cathode and arc currents as well as on hydrogen flow are presented. Europium (III) chloride as the source of the europium atoms was used. Europium ions were produced during collisions of evaporated and decomposed EuCl(3) molecules with fast electrons. The typical current of the europium ion beam extracted from the ion source was 25 microA for the extraction voltage of 25 kV. The ion source works without maintenance breaks for approximately 50 h, which enables high dose implantation. The presented ion source needs neither advanced high power supplies nor high vacuum regime. PMID:19405653

  20. Symmetric charge-transfer cross sections of IIIa rare-earth-metal elements

    SciTech Connect

    Hashida, Masaki; Sakabe, Shuji; Izawa, Yasukazu

    2011-03-15

    Symmetric charge-transfer cross sections of IIIa rare-earth-metal elements (Sc, Y, and Gd) in the impact energy range of 30 to 1000 eV were measured for the first time. The experiments were performed with a crossed-beam apparatus that featured primary ion production by photoionization with a tunable dye laser. Comparing the cross sections of IIIa rare-earth-metal elements ({sigma}{sub Sc}, {sigma}{sub Y}, and {sigma}{sub Gd}) with those of alkali metals or helium {sigma}{sub 0}, we found that {sigma}{sub 0{approx_equal}{sigma}Sc}<{sigma}{sub Y}<{sigma}{sub Gd{approx_equal}}2{sigma}{sub 0}at an impact energy of 1000 eV.

  1. On the Metal Ion Selectivity of Oxoacid Extractants

    SciTech Connect

    Hay, Benjamin; Chagnes, Alexandre; Cote, Gerard

    2013-01-01

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

  2. Method for treating rare earth-transition metal scrap

    DOEpatents

    Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.L.

    1992-12-29

    Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a rare earth fluoride-bearing flux of CaF[sub 2], CaCl[sub 2] or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy. 3 figs.

  3. Method for treating rare earth-transition metal scrap

    DOEpatents

    Schmidt, Frederick A. (Ames, IA); Peterson, David T. (Ames, IA); Wheelock, John T. (Nevada, IA); Jones, Lawrence L. (Des Moines, IA)

    1992-12-29

    Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.

  4. Electric Double-Layer Effects Induce Separation of Aqueous Metal Ions.

    PubMed

    Ji, Qinghua; An, Xiaoqiang; Liu, Huijuan; Guo, Lin; Qu, Jiuhui

    2015-11-24

    Metal ion separation is crucial to environmental decontamination, chromatography, and metal recovery and recycling. Theoretical studies have suggested that the ion distributions in the electric double-layer (EDL) region depend on the nature of the ions and the characteristics of the charged electrode surface. We believe that rational design of the electrode material and device structure will enable EDL-based devices to be utilized in the separation of aqueous metal ions. On the basis of this concept, we fabricate an EDL separation (EDLS) device based on sandwich-structured N-functionalized graphene sheets (CN-GS) for selective separation of aqueous toxic heavy metal ions. We demonstrate that the EDLS enables randomly distributed soluble ions to form a coordination-driven layer and electrostatic-driven layer in the interfacial region of the CN-GS/solution. Through tuning the surface potential of the CN-GS, the effective separation of heavy metal ions (coordination-driven layer) from alkali or alkaline earth metal ions (electrostatic-driven layer) can be achieved. PMID:26481603

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

    SciTech Connect

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

    2012-02-15

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

  6. Analysis of metallic pigments by ion microbeam

    NASA Astrophysics Data System (ADS)

    Pelicon, P.; Klanjšek-Gunde, M.; Kunaver, M.; Sim?i?, J.; Budnar, M.

    2002-05-01

    Metallic paints consist of metallic flakes dispersed in a resinous binder, i.e. a light-element polymer matrix. The spatial distribution and orientation of metallic flakes inside the matrix determines the covering efficiency of the paint, glossiness, and its angular-dependent properties such as lightness flop or color flop (two-tone). Such coatings are extensively used for a functional (i.e. security) as well as decorative purpose. The ion microbeam analysis of two types of silver paint with imbedded metallic flakes has been performed to determine the spatial distribution of the aluminum flakes in paint layer. The average sizes of the aluminum flakes were 23 ?m (size distribution 10-37) and 49 ?m (size distribution 34-75), respectively. The proton beam with the size of 2×2 ?m 2 at Ljubljana ion microprobe has been used to scan the surface of the pigments. PIXE mapping of Al K? map shows lateral distribution of the aluminum flakes, whereas the RBS slicing method reveals tomograms of the flakes in uppermost 7 ?m of the pigment layer. The series of point analysis aligned over the single flake reveal the flake angle in respect to the polymer matrix surface. The angular sensitivity is well below 1 angular degree.

  7. Transparent monolithic metal ion containing nanophase aerogels

    SciTech Connect

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

    1999-12-01

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

  8. Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae

    PubMed Central

    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.

    2015-01-01

    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, 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. PMID:25731976

  9. Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions.

    PubMed

    Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Ruhlandt-Senge, Karin; St Prix, Courtney; Zuniga, Maria F

    2009-01-01

    Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species. PMID:19360834

  10. Metal ion binding to iron oxides

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

  11. Rational Design of Metal Ion Sequestering Agents

    SciTech Connect

    Raymond, Kenneth N.

    2000-09-30

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

  12. How do metal ions direct ribozyme folding?

    NASA Astrophysics Data System (ADS)

    Denesyuk, Natalia A.; Thirumalai, D.

    2015-10-01

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

  13. Distribution coefficients of rare earth ions in cubic zirconium dioxide

    NASA Astrophysics Data System (ADS)

    Romer, H.; Luther, K.-D.; Assmus, W.

    1994-08-01

    Cubic zirconium dioxide crystals are grown with the skull melting technique. The effective distribution coefficients for Nd(exp 3+), Sm(exp 3+) and Er(sup 3+) as dopants are determined experimentally as a function of the crystal growth velocity. With the Burton-Prim-Slichter theory, the equilibrium distribution coefficients can be calculated. The distribution coefficients of all other trivalent rare earth ions can be estimated by applying the correlation towards the ionic radii.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  15. Predicting relative toxicity of metal ions to bacteria (Microtox{reg_sign}) using ion characteristics

    SciTech Connect

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

    1995-12-31

    The use of predictive effects models with metals has received little attention in toxicology. The purpose of this study was to predict the relative toxicity of individual metal ions and metal mixtures using ion characteristics. The concentration of metal resulting in a 50% reduction in light output (EC50) in marine bacteria (Vibrio fischeri) was determined for several metals using the Microtox{reg_sign} Toxicity Analyzer. Trends in metal toxicity were predicted by combining metal speciation calculations with empirical models based on metal ion characteristics. These trends were consistent for nine divalent metals (Ca{prime} Cd, Cu, Hg, Mg, Mn, Ni, Pb and Zn) whether the media mimicked salt water (NaC, medium) or freshwater (NaNO{sub 3} medium). When expanding the study to include an additional 14 mono-, di-, and trivalent metal ions, ion characteristics were still useful for predicting the relative toxicity of metal ions to bacteria. The prediction of nonadditive toxic effects using metal mixtures was also possible based on ion characteristics. Overall, models based on ion characteristics show much promise for predicting the relative toxicity of metal ions using the Microtox{reg_sign} assay.

  16. Separation of traces of metal ions from sodium matrices

    NASA Technical Reports Server (NTRS)

    Korkisch, J.; Orlandini, K. A.

    1969-01-01

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

  17. State promotion and neutralization ?f ions near metal surface

    NASA Astrophysics Data System (ADS)

    Zinoviev, A. N.

    2011-05-01

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

  18. Ion acoustic solitons in Earth's upward current region

    SciTech Connect

    Main, D. S.; Scholz, C.; Newman, D. L.; Ergun, R. E.

    2012-07-15

    The formation and evolution of ion acoustic solitons in Earth's auroral upward current region are studied using one- and two-dimensional (2D) electrostatic particle-in-cell simulations. The one-dimensional simulations are confined to processes that occur in the auroral cavity and include four plasma populations: hot electrons, H{sup +} and O{sup +} anti-earthward ion beams, and a hot H{sup +} background population. Ion acoustic solitons are found to form for auroral-cavity ion beams consistent with acceleration through double-layer (DL) potentials measured by FAST. A simplified one-dimensional model simulation is then presented in order to isolate the mechanisms that lead to the formation of the ion acoustic soliton. Results of a two-dimensional simulation, which include both the ionosphere and the auroral cavity, separated by a low-altitude DL, are then presented in order to confirm that the soliton forms in a more realistic 2D geometry. The 2D simulation is initialized with a U-shaped potential structure that mimics the inferred shape of the low altitude transition region based on observations. In this simulation, a soliton localized perpendicular to the geomagnetic field is observed to form and reside next to the DL. Finally, the 2D simulation results are compared with FAST data and it is found that certain aspects of the data can be explained by assuming the presence of an ion acoustic soliton.

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

    PubMed

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

    2005-03-23

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

  20. Observation of a rare earth ion-extractant complex arrested at the oil-water interface during solvent extraction.

    PubMed

    Bu, Wei; Yu, Hao; Luo, Guangming; Bera, Mrinal K; Hou, Binyang; Schuman, Adam W; Lin, Binhua; Meron, Mati; Kuzmenko, Ivan; Antonio, Mark R; Soderholm, L; Schlossman, Mark L

    2014-09-11

    Selective extraction of metal ions from a complex aqueous mixture into an organic phase is used to separate toxic or radioactive metals from polluted environments and nuclear waste, as well as to produce industrially relevant metals, such as rare earth ions. Selectivity arises from the choice of an extractant amphiphile, dissolved in the organic phase, which interacts preferentially with the target metal ion. The extractant-mediated process of ion transport from an aqueous to an organic phase takes place at the aqueous-organic interface; nevertheless, little is known about the molecular mechanism of this process despite its importance. Although state-of-the-art X-ray scattering is uniquely capable of probing molecular ordering at a liquid-liquid interface with subnanometer spatial resolution, utilizing this capability to investigate interfacial dynamical processes of short temporal duration remains a challenge. We show that a temperature-driven adsorption transition can be used to turn the extraction on and off by controlling adsorption and desorption of extractants at the oil-water interface. Lowering the temperature through this transition immobilizes a supramolecular ion-extractant complex at the interface during the extraction of rare earth erbium ions. Under the conditions of these experiments, the ion-extractant complexes condense into a two-dimensional inverted bilayer, which is characterized on the molecular scale with synchrotron X-ray reflectivity and fluorescence measurements. Raising the temperature above the transition leads to Er ion extraction as a result of desorption of ion-extractant complexes from the interface into the bulk organic phase. XAFS measurements of the ion-extractant complexes in the bulk organic phase demonstrate that they are similar to the interfacial complexes. PMID:25134605

  1. Rare earth-transition metal scrap treatment method

    DOEpatents

    Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.L.; Lincoln, L.P.

    1992-02-11

    Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. 3 figs.

  2. Rare earth-transition metal scrap treatment method

    DOEpatents

    Schmidt, Frederick A. (Ames, IA); Peterson, David T. (Ames, IA); Wheelock, John T. (Nevada, IA); Jones, Lawrence L. (Des Moines, IA); Lincoln, Lanny P. (Woodward, IA)

    1992-02-11

    Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets.

  3. Ion implantation of krypton in sputter-deposited metal matrices

    SciTech Connect

    Tingey, G.L.; McClanahan, E.D.; Nesbitt, J.F.

    1980-06-01

    Krypton 85 has been successfully stored in a metal matrix by bombarding the metal surface with krypton ions while the metal is being deposited by sputtering. The krypton is thus incorporated into the metal in concentrations approaching 200 cm/sup 3/ of Kr(STP)cm/sup 3/ of deposit. Cost estimates of a facility to perform this work are given. (GHT)

  4. Homogeneous Liquid-Liquid Extraction of Metal Ions with a Functionalized Ionic Liquid.

    PubMed

    Hoogerstraete, Tom Vander; Onghena, Bieke; Binnemans, Koen

    2013-05-16

    Binary mixtures of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water show an upper critical solution temperature. This solvent system has been used to extract metal ions by phase-transition extraction, using zwitterionic betaine as extractant. The system is efficient for the extraction of trivalent rare-earth, indium and gallium ions. This new type of metal extraction system avoids problems associated with the use of viscous ionic liquids, namely, the difficulty of intense mixing of the aqueous and ionic liquid phases by stirring. PMID:26282975

  5. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The provisions of this subpart are applicable to discharges resulting from...

  6. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting...

  7. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting...

  8. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting...

  9. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting...

  10. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting...

  11. Plasma immersion surface modification with metal ion plasma

    SciTech Connect

    Brown, I.G.; Yu, K.M. ); Godechot, X. Societe Anonyme d'Etudes et Realisations Nucleaires , 94 - Limeil-Brevannes )

    1991-04-01

    We describe here a novel technique for surface modification in which metal plasma is employed and by which various blends of plasma deposition and ion implantation can be obtained. The new technique is a variation of the plasma immersion technique described by Conrad and co-workers. When a substrate is immersed in a metal plasma, the plasma that condenses on the substrate remains there as a film, and when the substrate is then implanted, qualitatively different processes can follow, including' conventional' high energy ion implantation, recoil implantation, ion beam mixing, ion beam assisted deposition, and metallic thin film and multilayer fabrication with or without species mixing. Multiple metal plasma guns can be used with different metal ion species, films can be bonded to the substrate through ion beam mixing at the interface, and multilayer structures can be tailored with graded or abrupt interfaces. We have fabricated several different kinds of modified surface layers in this way. 22 refs., 4 figs.

  12. Plasma immersion ion implantation for reducing metal ion release

    SciTech Connect

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

    2012-11-06

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

  13. Source of Metal Ions Based on Penning Discharge

    NASA Astrophysics Data System (ADS)

    Kolodko, D. V.; Mamedov, N. V.; Sinelnikov, D. N.; Khodachenko, G. V.; Kaziev, A. V.; Tumarkin, A. V.; Pisarev, A. A.

    The deposition flux in magnetron discharges comprises two components: neutral particles and ions. In order to study the deposition process in detail, one needs to separate these components. Producing thin films by ion flux only requires development of a special ion source. The source of metal ions with Penning discharge was designed, numerically simulated and assembled. The characteristics of the ion source were determined experimentally.

  14. RKKY interactions and the anomalous Hall effect in metallic rare-earth pyrochlores.

    PubMed

    Lee, SungBin; Paramekanti, Arun; Kim, Yong Baek

    2013-11-01

    Motivated by experiments on Pr2Ir2O7, we consider metallic pyrochlore systems A2B2O7, where the A sites are occupied by rare-earth local moments and the B sites host 5d transition metal ions with itinerant strongly spin-orbit coupled electrons. Assuming non-Kramers doublets on the A site, we derive the RKKY interaction between them mediated by the B-site itinerant electrons and find extended non-Heisenberg interactions. Analyzing a simplified model of the RKKY interaction, we uncover a local moment phase with coexisting spiral Ising-like magnetic dipolar and XY-like quadrupolar ordering. This state breaks time-reversal and lattice symmetries, and reconstructs the B-site electronic band structure, producing a Weyl metallic phase with an intrinsic anomalous Hall effect and an undetectably small magnetization. We discuss implications of our results for Pr2Ir2O7. PMID:24266480

  15. Pentadienyl chemistry of the heavy alkaline-earth metals revisited.

    PubMed

    Reiners, Matthias; Fecker, Ann Christin; Freytag, Matthias; Jones, Peter G; Walter, Marc D

    2014-05-14

    Open-metallocenes of the heavy alkaline-earth metals [(?(5)-Pdl')2M(thf)n] (M = Ca (1), Sr (2), n = 1; M = Ba (3), n = 2; Pdl' = 2,4-tBu2C5H5) are readily prepared by salt-metathesis between MI2 and KPdl' and characterized by NMR spectroscopy and X-ray diffraction studies. PMID:24652227

  16. Steady-state superradiance with alkaline-earth-metal atoms

    SciTech Connect

    Meiser, D.; Holland, M. J.

    2010-03-15

    Alkaline-earth-metal-like atoms with ultranarrow transitions open the door to a new regime of cavity quantum electrodynamics. That regime is characterized by a critical photon number that is many orders of magnitude smaller than what can be achieved in conventional systems. We show that it is possible to achieve superradiance in steady state with such systems. We discuss the basic underlying mechanisms as well as the key experimental requirements.

  17. Isotopic fractionation of alkali earth metals during carbonate precipitation

    NASA Astrophysics Data System (ADS)

    Yotsuya, T.; Ohno, T.; Muramatsu, Y.; Shimoda, G.; Goto, K. T.

    2014-12-01

    The alkaline earth metals such as magnesium, calcium and strontium play an important role in a variety of geochemical and biological processes. The element ratios (Mg/Ca and Sr/Ca) in marine carbonates have been used as proxies for reconstruction of the past environment. Recently several studies suggested that the study for the isotopic fractionation of the alkaline earth metals in marine carbonates has a potentially significant influence in geochemical research fields (e.g. Eisenhauer et al., 2009). The aim of this study is to explore the influence of carbonate polymorphs (Calcite and Aragonite) and environmental factors (e.g., temperature, precipitation rate) on the level of isotopic fractionation of the alkaline earth metals. We also examined possible correlations between the level of isotopic fractionation of Ca and that of other alkaline earth metals during carbonate precipitation. In order to determine the isotope fractionation factor of Mg, Ca and Sr during carbonate precipitation, calcite and aragonite were synthesized from calcium bicarbonate solution in which the amount of magnesium was controlled based on Kitano method. Calcium carbonates were also prepared from the mixture of calcium chlorite and sodium hydrogen carbonate solutions. The isotope fractionation factors were measured by MC-ICPMS. Results suggested that the level of isotopic fractionation of Mg during carbonate precipitation was correlated with that of Sr and that the change of the carbonate crystal structure could make differences of isotopic fractionations of Mg and Ca, however no difference was found in the case of Sr. In this presentation, the possible mechanism will be discussed.

  18. The possible role of metal ions and clays in prebiotic chemistry

    NASA Technical Reports Server (NTRS)

    Lawless, J. G.; Edelson, E. H.

    1980-01-01

    Eight homoionic bentonites were prepared using alkali, alkaline earth, and transition metal ions as counterions. The interaction of the clays with 5'-AMP was studied and it was found that the alkali metal-substituted clays did not remove any nucleotide from dilute solution, and that zinc-bentonite adsorbed the most (98%). In addition, study of the interaction of seven other nucleotides with zinc-bentonite showed that the purine nucleotides were more strongly absorbed than the pyrimidine nucleotides. Langmuir isotherms were obtained for these systems and the adsorption data were explained by the adsorption coefficient and the accessibility of metal for binding.

  19. Ion implantation enhanced metal-Si-metal photodetectors

    SciTech Connect

    Sharma, A.K.; Scott, K.A.M.; Brueck, S.R.J. . Center for High Technology Materials); Zolper, J.C.; Myers, D.R. )

    1994-05-01

    The quantum efficiency and frequency response of simple Ni-Si-Ni metal-semiconductor-metal (MSM) photodetectors at long wavelengths are significantly enhanced with a simple, ion-implantation step to create a highly absorbing region [approximately] 1 [mu]m below the Si surface. The internal quantum efficiency is improved by a factor of [approximately] 3 at 860 nm (to 64%) and a full factor of ten at 1.06 [mu]m (to 23%) as compared with otherwise identical unimplanted devices. Dark currents are only slightly affected by the implantation process and are as low as 630 pA for a 4.5-[mu]m gap device at 10-V bias. Dramatic improvement in the impulse response is observed, 100 ps vs. 600 ps, also at 10-V bias and 4.5-[mu]m gap, due to the elimination of carrier diffusion tails in the implanted devices. Due to its planar structure, this device is fully VLSI compatible. Potential applications include optical interconnections for local area networks and multi-chip modules.

  20. Improvements in estimated entropies and related thermodynamic data for aqueous metal ions.

    PubMed

    Johnson, David A; Nelson, Peter G

    2012-06-01

    New estimated standard entropies for some aqueous metal ions are obtained by taking account of magnetic and symmetry contributions. By combining them with an analysis of literature data, improved experimental and estimated values are derived for the standard enthalpies and Gibbs energies of formation of the aqueous ions of titanium, vanadium, chromium, manganese, cerium, and praseodymium. Separate entropy correlations are used for each primary coordination number, and the size dependence is represented by the reciprocal of the metal-oxygen distance in that coordination. The new scheme is consistent with recent work on the coordination of Hg(2+)(aq), Pb(2+)(aq), and tripositive rare earth ions. It differs from its predecessors in indicating a larger variation of the standard molar entropies of aqueous ions with coordination number. The value of S(?)(Be(2+), aq) is discussed in this context. PMID:22621251

  1. On the onset voltage of liquid metal ion sources

    NASA Astrophysics Data System (ADS)

    Mair, G. L. R.

    1989-09-01

    Various formulae for the onset voltage corresponding to liquid metal ion sources (LMIS) of different design are compared to a wide range of experimental data. Provided the correct formula is used in each particular case, the agreement between theory and experiment is satisfactory. Predicting the source starting voltage correctly is of use in ion source and ion column design.

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

    SciTech Connect

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

    1988-01-01

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

  3. Separation of rare earths from transition metals by liquid-liquid extraction from a molten salt hydrate to an ionic liquid phase.

    PubMed

    Rout, Alok; Binnemans, Koen

    2014-02-28

    The solvent extraction of trivalent rare-earth ions and their separation from divalent transition metal ions using molten salt hydrates as the feed phase and an undiluted fluorine-free ionic liquid as the extracting phase were investigated in detail. The extractant was tricaprylmethylammonium nitrate, [A336][NO3], and the hydrated melt was calcium nitrate tetrahydrate, Ca(NO3)2·4H2O. The extraction behavior of rare-earth ions was studied for solutions of individual elements, as well as for mixtures of rare earths in the hydrated melt. The influence of different extraction parameters was investigated: the initial metal loading in the feed phase, percentage of water in the feed solution, equilibration time, and the type of hydrated melt. The extraction of rare earths from Ca(NO3)2·4H2O was compared with extraction from CaCl2·4H2O by [A336][Cl] (Aliquat 336). The nitrate system was found to be the better one. The extraction and separation of rare earths from the transition metals nickel, cobalt and zinc were also investigated. Remarkably high separation factors of rare-earth ions over transition metal ions were observed for extraction from Ca(NO3)2·4H2O by the [A336][NO3] extracting phase. Furthermore, rare-earth ions could be separated efficiently from transition metal ions, even in melts with very high concentrations of transition metal ions. Rare-earth oxides could be directly dissolved in the Ca(NO3)2·4H2O phase in the presence of small amounts of Al(NO3)3·9H2O or concentrated nitric acid. The efficiency of extraction after dissolving the rare-earth oxides in the hydrated nitrate melt was identical to extraction from solutions with rare-earth nitrates dissolved in the molten phase. The stripping of the rare-earth ions from the loaded ionic liquid phase and the reuse of the recycled ionic liquid were also investigated in detail. PMID:24352299

  4. Characteristics of the ion pressure tensor in the earth`s magnetosheath

    SciTech Connect

    Li, X.; Lewis, H.R.; LaBelle, J.

    1995-03-15

    AMPTE/IRM satellite data are used to examine characteristics of the ion pressure tensor in the earth`s magnetosheath. The eigenvalues and principal axes of the pressure tensor are computed, and the directions of the principal axes are compared to the direction of the independently measured magnetic field B. When the pressure tensor is anisotropic, as is usually the case in the magnetosheath, one of its eigenvalues is observed to be distinguishable from the other two, which are about equal to one another. Thus, the eigenvector associated with the distinguishable eigenvalue defines an axis of symmetry of the pressure tensor. The symmetry axis is generally not parallel to B. New features of the plasma distribution function are revealed by using the actual eigenvalues of the pressure tensor rather than the usual p{perpendicular} and p{parallel}, where {perpendicular} and {parallel} denote directions perpendicular and parallel to B. 15 refs., 5 figs.

  5. Magnetism of perovskite cobaltites with Kramers rare-earth ions

    SciTech Connect

    Jirák, Z. Hejtmánek, J.; Knížek, K.; Novák, P.; Šantavá, E.; Fujishiro, H.

    2014-05-07

    The band-gap insulators RECoO{sub 3} (RE?=?Nd{sup 3+}, Sm{sup 3+}, and Dy{sup 3+}) with Co{sup 3+} ions stabilized in the non-magnetic low-spin state have been investigated by specific heat measurements. The experiments evidence an antiferromagnetic ordering of the rare earths with Néel temperature of T{sub N}?=?1.25, 1.50, and 3.60?K for NdCoO{sub 3}, SmCoO{sub 3}, and DyCoO{sub 3}, respectively. With increasing external field, the lambda peak in specific heat, indicative of the transition, shifts to lower temperatures and vanishes for field of about 3?T. Starting from this point, a broader Schottky peak is formed, centered in 1?K range, and its position is moved to higher temperatures proportionally to applied field. The origin of the peak is in Zeeman splitting of the ground Kramers doublet, and the gradual shift with field defines effective g-factors for the rare-earth pseudospins in studied compounds. The results obtained are confronted with the calculations of crystal field splitting of the rare-earth multiplets.

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

    NASA Technical Reports Server (NTRS)

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

    1966-01-01

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

  7. Numerical simulations of the optical gain of crystalline fiber doped by rare earth and transition ion

    NASA Astrophysics Data System (ADS)

    Daoui, A. K.; Boubir, B.; Adouane, A.; Demagh, N.; Ghoumazi, M.

    2015-02-01

    A fiber laser is a laser whose gain medium is a doped fiber, although lasers whose cavity is made wholly of fibers have also been called fiber lasers. The gain media in a fiber laser is usually fiber doped with rare-earth ions, such as erbium (Er), neodymium (Nd), ytterbium (Yb), thulium (Tm), or praseodymium (Pr), which is doped into the core of the optical fiber, similar to those used to transmit telecommunications signals. Fiber lasers find many applications in materials processing, including cutting, welding, drilling, and marking metal. To maximize their market penetration, it is necessary to increase their output power. In this work, we present a detailed study based on the numerical simulation using MATLAB, of one of the principal characteristics of a fiber laser doped with rare earth ions and transition ion. The gain depends on several parameters such as the length of the doped fiber, the density, the pump power, noise, etc.). The used program resolves the state equations in this context together with those governing the light propagation phenomena. The developed code can also be used to study the dynamic operating modes of a doped fiber laser.

  8. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

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

    2015-04-07

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

  9. Applications of the MEVVA high current metal ion source

    SciTech Connect

    Brown, I.G.

    1986-08-01

    A new kind of ion source has been developed in which a metal vapor vacuum arc (MEVVA) is used to produce the plasma from which the ion beam is extracted. The novel and exciting feature of this source is the very high metal ion beam current attainable. A total ion beam current of over 1 Ampere has been extracted from the embodiment of the concept that we're presently using, and this is not a limit of the method. The source was developed to upgrade the uranium ion beam intensity of the Bevatron, LBL's heavy ion synchrotron, for basic nuclear physics research. Other important applications include its use within the Heavy Ion Fusion research effort; for ion implantation; and for other basic research uses. In this paper the source is described briefly, its performance outlined, and its poential and limitations for a variety of applications is discussed.

  10. Metal ion-induced lateral aggregation of filamentous viruses fd and M13.

    PubMed Central

    Tang, Jay X; Janmey, Paul A; Lyubartsev, Alexander; Nordenskiöld, Lars

    2002-01-01

    We report a detailed comparison between calculations of inter-filament interactions based on Monte-Carlo simulations and experimental features of lateral aggregation of bacteriophages fd and M13 induced by a number of divalent metal ions. The general findings are consistent with the polyelectrolyte nature of the virus filaments and confirm that the solution electrostatics account for most of the experimental features observed. One particularly interesting discovery is resolubilization for bundles of either fd or M13 viruses when the concentration of the bundle-inducing metal ion Mg(2+) or Ca(2+) is increased to large (>100 mM) values. In the range of Mg(2+) or Ca(2+) concentrations where large bundles of the virus filaments are formed, the optimal attractive interaction energy between the virus filaments is estimated to be on the order of 0.01 kT per net charge on the virus surface when a recent analytical prediction to the experimentally defined conditions of resolubilization is applied. We also observed qualitatively distinct behavior between the alkali-earth metal ions and the divalent transition metal ions in their action on the charged viruses. The understanding of metal ions-induced reversible aggregation based on solution electrostatics may lead to potential applications in molecular biology and medicine. PMID:12080143

  11. Origins of energetic ions in the Earth's magnetosheath

    NASA Technical Reports Server (NTRS)

    Fuselter, S. A.; Shelley, E. G.; Klumpar, D. M.

    1992-01-01

    The analysis and interpretation of the combined scientific data from the Hot Plasma Composition Experiment (HPCE) and the Charge Energy Mass (CHEM) spectrometer on the Active Mesospheric Particle Tracer Experiment (AMPTE) Charge Composition Explorer (CCE) spacecraft are discussed. These combined data sets have and will be used to survey the energetic ion environment in the Earth's magnetosheath to determine the origins and relative strengths of the energetic ion populations found there. A computer code was developed to analyze and interpret the data sets. The focus of the first year was on the determination of the contribution of leaked magnetospheric protons to the total energetic proton population. Emphasis was placed on intervals when the AMPTE spacecraft was in the plasma depletion layer because it was argued that in this region, only the leaked population contributes to the energetic ion population. Manipulation of the CHEM data and comparison of the CHEM and HPCE data over their common energy range near the magnetopause also contributed directly to a second study of that region.

  12. Detection of toxic metal ions with near-infrared compounds

    NASA Astrophysics Data System (ADS)

    Casay, Guillermo A.; Czuppon, Tibor; Evans, Lawrence, III; Patonay, Gabor

    1994-10-01

    The determination of toxic metal ions in water using near-infrared compounds synthesized in our laboratories will be reported. Several near-infrared tetrasubstituted chloroaluminum 2,3-naphthalocyanine derivatives with spectral characteristics (absorbance and fluorescence) between 700 nm and 1000 nm have been used in these investigations. In the presence of metal ions the NIR dye's absorbance maximum undergoes a bathochromic shift of about 25 nm accompanied by changes in the fluorescence spectra along with molecular lifetime. The response of the NIR dye in the presence of several concentrations of toxic metal ions will be reported. The fluorescence intensity generated by the complex formed by the metal ion and the dye was monitored by (a) a modified commercially available spectrofluorometer and (b) an NIR instrument developed in our laboratories. The fluorescence intensity changes measured with the probe in the presence of metal ions can be used to construct a calibration curve for the monitoring of contaminants' metal ions in the environment. The effect of metal ions on the lifetime of the NIR dye as compared to the uncomplexed dye will be reported. The NIR instrument consists of a semiconductor laser diode, the NIR dye and a detector. The output wavelength of a 780 nm diode (used as the excitation source) matched the absorbance of these dyes and improved the detection limits of the analytes. Long term stability of the probe was investigated by a week-long period of observation. After one week the intensity varies by only 2%, suggesting suitably for long storage.

  13. Impregnated-electrode-type liquid metal ion source

    SciTech Connect

    Ishikawa, J.; Takagi, T.

    1984-12-01

    An impregnated-electrode-type liquid metal ion source has been developed in which a sintered porous tungsten tip is used. The flow rate of the liquid metal can be controlled by selecting the diameters of the tungsten powders to be sintered (10 and 100 ..mu..m). Since the liquid metal can be stably supplied to the tip head, stable operation in a wide range from low (a few ..mu..A) to high ion current (a few hundred ..mu..A) is possible for various metals such as gallium and gold. Moreover, it is also a potential ion source with liquid metals such as silver with high vapor pressure at the melting point. A new method of holding and directly heating the main component of the ion source by means of knife-edged electrodes with a spring is extremely effective for high temperature operation.

  14. A geological reconnaissance of electrical and electronic waste as a source for rare earth metals

    E-print Network

    A geological reconnaissance of electrical and electronic waste as a source for rare earth metals structure (Nickel, 2005). They are the starting point for the production of metals such as rare earth Resource classification Rare earth element Waste electrical and electronic equipment a b s t r a c

  15. Alkaline and alkaline earth metal phosphate halides and phosphors

    DOEpatents

    Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

    2012-11-13

    Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

  16. The Transport of Solar Ions Through the Earth's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.

    1999-01-01

    This report covers the initial phase of an investigation that was originally selected by NASA Headquarters for funding by a grant but was later transferred to NASA GSFC for continued funding under a new and separate contract. The principal objective of the investigation, led by Dr. O.W. Lennartsson, is to extract information about the solar origin plasma in Earth's magnetosphere, specifically about the entry and transport of this plasma, using energetic (10 eV/e to 18 keV/e) ion composition data from the Lockheed Plasma Composition Experiment on the NASA/ESA International Sun-Earth Explorer One (ISEE 1) satellite. These data were acquired many years ago, from November 1977 through March of 1982, but, because of subsequent failures of similar experiments on several other spacecraft, they are still the only substantial ion composition data available from Earth's magnetotail, beyond 10 R(sub E), in the critically important sub-kev to keV energy range. All of the Lockheed data now exist in a compacted scientific format, suitable for large-scale statistical investigations, which has been archived both at Lockheed Martin in Palo Alto and at the National Space Science Data Center (NSSDC) in Greenbelt. The completion of the archiving, by processing the remaining half of the data, was made possible by separate funding through a temporary NASA program for data restoration and was given priority over the data analysis by a no-cost extension of the subject grant. By chance, the period of performance coincided with an international study of source and loss processes of magnetospheric plasma, sponsored by the International Space Science Institute (ISSI) in Bern, Switzerland, for which Dr. Lennartsson was invited to serve as one of 12 co-chairs. This study meshed well with the continued analysis of the NASA/Lockheed ISEE ion composition data and provided a natural forum for a broader discussion of the results from this unique experiment. What follows is arranged, for the most part, in the context of the ISSI project.

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

    PubMed

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

    2015-12-23

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

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

    SciTech Connect

    Bond, A. H.

    1998-05-19

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

  19. Separation of platinum group metal ions by Donnan dialysis

    SciTech Connect

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

    1985-10-01

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

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

    PubMed Central

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

    2015-01-01

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

  1. A Comparative Study of Electrical Resistivity of Liquid Alkaline Earth Metals

    NASA Astrophysics Data System (ADS)

    Korkmaz, S. D.; Korkmaz, ?.; Resulo?lu, F.

    2007-04-01

    The resistivities of liquid alkaline earth metals are investigated using Ziman formula and the alternative expression based on Kubo formula suggested by Ünal and Alkan [J. Phys. Soc. Jpn. 62 (1993) 2425]. As the input pseudopotential the individual version of the electron-ion potential proposed by Fioalhais and coworkers which was originally developed for solid state is used and static structure factors are derived from the solution of Ornstein-Zernike integral equation with Rogers-Young closure. Good agreement with experiment is found for liquid Mg using both formulas. For Ca, Sr and Ba the agreement between the calculated values using Ziman formula and experimental data is less satisfactory. From present investigations, it is shown that the formula based on Kubo formula suggested by Ünal and Alkan is the better chose for the resistivity calculations of liquid Ca, Sr and Ba metals.

  2. Molten metal containment vessel with rare earth oxysulfide protective coating thereon and method of making same

    DOEpatents

    Krikorian, Oscar H. (Danville, CA); Curtis, Paul G. (Tracy, CA)

    1992-01-01

    An improved molten metal containment vessel is disclosed in which wetting of the vessel's inner wall surfaces by molten metal is inhibited by coating at least the inner surfaces of the containment vessel with one or more rare earth oxysulfide or rare earth sulfide compounds to inhibit wetting and or adherence by the molten metal to the surfaces of the containment vessel.

  3. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary...

  4. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary...

  5. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary...

  6. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary...

  7. Proposal for laser-cooling of rare-earth ions

    E-print Network

    Maxence Lepers; Ye Hong; Jean-François Wyart; Olivier Dulieu

    2015-08-25

    The efficiency of laser-cooling relies on the existence of an almost closed optical-transition cycle in the energy spectrum of the considered species. In this respect rare-earth elements exhibit many transitions which are likely to induce noticeable leaks from the cooling cycle. In this work, to determine whether laser-cooling of singly-ionized erbium Er$^+$ is feasible, we have performed accurate electronic-structure calculations of energies and spontaneous-emission Einstein coefficients of Er$^+$, using a combination of \\textit{ab initio} and least-square-fitting techniques. We identify five weak closed transitions suitable for laser-cooling, the broadest of which is in the kilohertz range. For the strongest transitions, by simulating the cascade dynamics of spontaneous emission, we show that repumping is necessary, and we discuss possible repumping schemes. We expect our detailed study on Er$^+$ to give a good insight into laser-cooling of neighboring ions like Dy$^+$.

  8. Proposal for laser-cooling of rare-earth ions

    E-print Network

    Lepers, Maxence; Wyart, Jean-François; Dulieu, Olivier

    2015-01-01

    The efficiency of laser-cooling relies on the existence of an almost closed optical-transition cycle in the energy spectrum of the considered species. In this respect rare-earth elements exhibit many transitions which are likely to induce noticeable leaks from the cooling cycle. In this work, to determine whether laser-cooling of singly-ionized erbium Er$^+$ is feasible, we have performed accurate electronic-structure calculations of energies and spontaneous-emission Einstein coefficients of Er$^+$, using a combination of \\textit{ab initio} and least-square-fitting techniques. We identify five weak closed transitions suitable for laser-cooling, the broadest of which is in the kilohertz range. For the strongest transitions, by simulating the cascade dynamics of spontaneous emission, we show that repumping is necessary, and we discuss possible repumping schemes. We expect our detailed study on Er$^+$ to give a good insight into laser-cooling of neighboring ions like Dy$^+$.

  9. Incorporation of impurity metal ions in electrolytic manganese dioxide

    SciTech Connect

    Tamura, Hiroki; Ishizeki, Kenji; Nagayama, Masaichi; Furuichi, Ryusaburo . Faculty of Engineering)

    1994-08-01

    The amounts of impurity metal ions incorporated into electrolytic manganese dioxide (EMD) during its preparation were measured as a function of metal ion concentration and current densities. The amount of incorporated ions increased in proportion to the concentration in solution, and at a fixed concentration it was different from ion to ion: Ni[sup 2+] < Zn[sup 2+] < Co[sup 2+] < Cu[sup 2+] < Fe[sup 2+] < Pb[sup 2+]. The specific surface area of the formed EMD was larger for impurity ions with higher incorporation affinity. Further, the adsorption of ions on the surface of a ready-made manganese dioxide sample (ICI2) was examined, and modeling of the adsorption behavior was attempted. The amounts of adsorbed ions at a fixed concentration in solution and pH 0.7 (where EMD is produced) were obtained by the ion-adsorption model. There was a strong correlation between the amount incorporated and the amount of adsorption, suggesting a mechanism in which EMD is contaminated through adsorption on its new growing surface. The increase in specific surface area of EMD with contaminants was interpreted to be due to a suppression of the growth of EMD at the adsorbed foreign ion sites, resulting in EMD with many defects or smaller particle sizes. The opposite effect of current density on incorporation for the two groups of metal ions was discussed.

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

    PubMed Central

    Cassat, James E.

    2013-01-01

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

  11. Metal-metal bonding and interstitials in reduced rare-earth metal halides

    SciTech Connect

    Corbett, J.D.; Dudis, D.S.; Ford, J.E.; Hwu, S.J.; Meyer, G.; Wijeyesekera, S.

    1986-01-01

    Exploratory research in recent years has shown the rare-earth elements in their highly reduced halides exhibit a remarkable ability to undergo cluster formation, some as isolated units and others as infinite chains or slabs containing double-metal layers. Only a few of the elements have been studied in any detail, principally scandium, yttrium and gadolinium. Many of these new compounds are uniquely stabilized by a second-period element bound within each cluster, for example, in Sc/sub 7/Cl/sub 12/B, Sc/sub 5/Cl/sub 8/C, Y/sub 2/Cl/sub 2/C and Li/sub y/YClH/sub x/, although a few structures evidently represent true binaries, e.g., with Sc/sub 7/Cl/sub 10/ and Y/sub 2/Cl/sub 3/. The known phases and their structures are briefly reviewed, and some relevant information from extended-Hueckel band calculations and uv photoelectron spectroscopy noted. 28 refs.

  12. Probing the Role of Metal Ions in RNA Catalysis: Kinetic and Thermodynamic Characterization of a Metal Ion Interaction with the 2-Moiety of the Guanosine

    E-print Network

    Herschlag, Dan

    Probing the Role of Metal Ions in RNA Catalysis: Kinetic and Thermodynamic Characterization of a Metal Ion Interaction with the 2-Moiety of the Guanosine Nucleophile in the Tetrahymena Group I Ribozyme: Deciphering the role of individual metal ions in RNA catalysis is a tremendous challenge, as numerous metal

  13. Preparation and structure of carbonated calcium hydroxyapatite substituted with heavy rare earth ions

    SciTech Connect

    Yasukawa, Akemi; Kandori, Kazuhiko; Tanaka, Hidekazu; Gotoh, Keiko

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer LnCaHap solid solution particles were prepared using five types of heavy rare earth ions by a precipitation method. Black-Right-Pointing-Pointer The length and the crystallinity of the LnCaHap particles first increased and then decreased with increasing Ln{sup 3+} contents. Black-Right-Pointing-Pointer A series of YCaHap solid solution particles formed with Y/(Y + Ca) = 0-0.10 were investigated using various methods in detail. -- Abstract: Calcium hydroxyapatite (CaHap) particles substituted five types of heavy rare earth ions (Ln: Y{sup 3+}, Gd{sup 3+}, Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+}) were synthesized using a precipitation method and characterized using various means. These Ln ions strongly affected the crystal phases and the structures of the products. With increasing Ln/(Ln + Ca) in the starting solution ([X{sub Ln}]), the length and the crystallinity of the particles first increased and then decreased. The rare earth metal-calcium hydroxyapatite (LnCaHap) solid solution particles were obtained at [X{sub Y}] {<=} 0.10 for substituting Y system and at [X{sub Ln}] {<=} 0.01-0.03 for substituting the other Ln systems. LnPO{sub 4} was mixed with LnCaHap at higher [X{sub Ln}] for all Ln systems. A series of yttrium-calcium hydroxyapatite (YCaHap) solid solutions with [X{sub Y}] = 0-0.10 were investigated using XRD, TEM, ICP-AES, IR and TG-DTA in detail.

  14. Metal sulfide and rare-earth phosphate nanostructures and methods of making same

    DOEpatents

    Wong, Stanislaus; Zhang, Fen

    2014-05-13

    The present invention provides a method of producing a crystalline metal sulfide nanostructure. The metal is a transitional metal or a Group IV metal. In the method, a porous membrane is placed between a metal precursor solution and a sulfur precursor solution. The metal cations of the metal precursor solution and sulfur ions of the sulfur precursor solution react, thereby producing a crystalline metal sulfide nanostructure.

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

    DOEpatents

    Horwitz, Earl P. (Argonne, IL); Gatrone, Ralph C. (Argonne, IL); Nash, Kenneth L. (Argonne, IL)

    1994-01-01

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

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

    DOEpatents

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

    1994-07-26

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

  17. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    NASA Astrophysics Data System (ADS)

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia

    2015-10-01

    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

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

    SciTech Connect

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

    1996-10-01

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

  19. Molecular rare-earth-metal hydrides in non-cyclopentadienyl environments.

    PubMed

    Fegler, Waldemar; Venugopal, Ajay; Kramer, Mathias; Okuda, Jun

    2015-02-01

    Molecular hydrides of the rare-earth metals play an important role as homogeneous catalysts and as counterparts of solid-state interstitial hydrides. Structurally well-characterized non-metallocene-type hydride complexes allow the study of elementary reactions that occur at rare-earth-metal centers and of catalytic reactions involving bonds between rare-earth metals and hydrides. In addition to neutral hydrides, cationic derivatives have now become available. PMID:25413985

  20. Smart textile device using ion polymer metal compound.

    PubMed

    Nakamura, Taro; Ihara, Tadashi

    2013-01-01

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

  1. Multiple roles of metal ions in large ribozymes.

    PubMed

    Donghi, Daniela; Schnabl, Joachim

    2011-01-01

    Since the discovery of catalytic RNA molecules (ribozymes), intense research has been devoted to understand their structure and activity. Among RNA molecules, the large ribozymes, namely group I and group II introns and RNase P, are of special importance. The first two ribozymes are known for their ability to perform self-splicing while RNase P is responsible for the 5'-end maturation of tRNA in bacteria, archea, and eukaryotes. All three groups of ribozymes show a significant requirement for metal ions in order to establish the active tertiary structure that enables catalysis. The primary role of both monovalent and divalent metal ions is to screen the negative charge associated with the phosphate sugar backbone, but the metal ions also play an active role in catalysis. Biochemical and biophysical investigations, supported by recent findings from X-ray crystal structures, allow clarifying and rationalizing both the structural and catalytic roles of metal ions in large ribozymes. In particular, the "two-metal-ion mechanism", describing how metal ions in the active center take part in catalysis, has been largely corroborated. PMID:22010273

  2. Detection of Metallic Compounds in Rocket Plumes Using Ion Probes

    NASA Technical Reports Server (NTRS)

    Dunn, Robert W.

    1998-01-01

    This grant experimentally verified that ion probes can consistently detect metallic compounds in a hybrid rocket plume. Two electrostatic detection methods were tested. The first method used an unbiased ion probe. It responded to collisions or near collisions with charged particulates. The amplitude of the response to metallic ions always exceeded that of the combustion products. The second device was a cylindrical Gaussian surface that surrounded, but did not touch, the plume. A charge imbalance in the plume induced a current in cylinder that was detected by a sensitive amplifier. The probe was more sensitive to metallic compounds than the cylinder. However, the Gaussian cylinder demonstrated sufficient sensitivity to warrant serious future consideration. Since the cylinder is nonintrusive, it is particularly attractive. Apparently, ions formed during combustion transfer to the metallic impurities. The formation of these metallic ions slows the ion recombination rate and helps preserve charges in the plume. The electrostatic detectors, in turn, respond to the charges carried by the metallic impurities.

  3. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

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

  4. Effect of rare earth ions on the properties of glycine phosphite single crystals

    NASA Astrophysics Data System (ADS)

    Senthilkumar, K.; Moorthy Babu, S.; Kumar, Binay; Bhagavannarayana, G.

    2013-01-01

    Optically transparent glycine phosphite (GPI) single crystals doped with rare earth metal ions (Ce, Nd and La) were grown from aqueous solution by employing the solvent evaporation and slow cooling methods. Co-ordination of dopants with GPI was confirmed by X-ray fluorescence spectroscopic analysis. Single crystal X-ray diffraction analysis was carried out to determine the lattice parameters and to analyze the structural morphology of GPI with dopants, which indicates that cell parameters of doped crystals were significantly varied with pure GPI. Crystalline perfection of doped GPI crystals was determined by high resolution X-ray diffraction analysis by means of full width at half maximum values. Influence of the dopants on the optical properties of the material was determined. Paraelectric to ferroelectric transition temperature (Tc) of doped GPI crystals were identified using differential scanning calorimetric measurements. Piezoelectric charge coefficient d33 was measured for pure and doped GPI crystals. Hysteresis (P-E) loop was traced for ferroelectric b-axis and (100) plane of pure and doped GPI crystals with different biasing field and ferroelectric parameters were calculated. Mechanical stability of crystals was determined by Vickers microhardness measurements; elastic stiffness constant 'C11' and yield strength '?y' were calculated from hardness values. Mechanical and ferroelectric properties of doped crystals were improved with doping of rare earth metals.

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

    SciTech Connect

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

    2007-01-01

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

  6. Detection of Heavy Metal Ions Based on Quantum Point Contacts

    E-print Network

    Tao, Nongjian

    quantum phenomena begin to emerge, which offer not only exciting opportunities to study fundamental chem on many living organisms and the consequence of heavy metal ions not being biodegradable. To date, heavy because they provide an early detection of trace metal contaminants while minimizing errors, labor

  7. Effect of Metal Ions on Melanin – Local Anaesthetic Drug Complexes

    PubMed Central

    Buszman, Ewa; Betlej, Bo?ena; Wrze?niok, Dorota; Radwa?ska-Wala, Bo?ena

    2003-01-01

    The affinity of melanin biopolymers for metal ions, drugs and other organic compounds is an important factor in the etiology of toxic retinopathy, hiperpigmentation, otic lesions and irreversible extrapyramidal disorders. The aim of the presented work was to examine the interaction of local anaesthetic drugs used in ophthalmology with model DOPA-melanin in the presence of metal ions. It has been demonstrated that the analyzed drugs form complexes with melanin biopolymer. Based on the .values of association constants,, the following order of drugs affinity to melanin was found: tetracaine > procaine >> bupivacaine > lidocaine. It has also been shown that Cu2+ and Zn2+ ions administered to DOPA-melanin before complexing with drugs decrease the total amount of local anaesthetics bound to melanin. The blocking of some active centers in melanin molecules by metal ions, which potentially exist in living systems, may change the clinical therapeutic efficiency of the analyzed local anaesthetic drugs. PMID:18365047

  8. THEMIS observations of electrostatic ion cyclotron waves and associated ion heating near the Earth's dayside magnetopause

    NASA Astrophysics Data System (ADS)

    Tang, Xiangwei; Cattell, Cynthia; Lysak, Robert; Wilson, Lynn B.; Dai, Lei; Thaller, Scott

    2015-05-01

    We present the first observations of large-amplitude electrostatic ion cyclotron (EIC) waves near the Earth's dayside magnetopause at MLT of ˜14 using data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites. The EIC waves were identified in a boundary layer in the magnetosphere adjacent to the magnetopause where reconnection was occurring. The EIC wave power was primarily at 2fcH (where fcH is the hydrogen cyclotron frequency) and simultaneously observed with perpendicular ion heating. The EIC waves had electric field amplitudes as large as 30 mV/m peak to peak with significant power both perpendicular and parallel to the magnetic field. These amplitudes were greater than those of previously observed ion cyclotron harmonics at the nightside magnetopause. The EIC waves occurred during an interval of enhancements in the quasi-static electric field and fluctuations in the background magnetic field, plasma density, and temperatures. The observations indicate that a plasma density gradient is a possible source of free energy for the EIC waves. The observed flow shears are not large enough to drive the waves. Whistler mode waves were identified near the EIC wave region but closer to the magnetopause in a region with slightly higher ion and electron temperatures.

  9. Metal-Ion-Dependent Motion of Self-Propelled Droplets Due to the Marangoni Effect.

    PubMed

    Ban, Takahiko; Nakata, Hiroki

    2015-06-11

    Chemically driven self-propulsion of soft matter is useful for various applications because it can move toward a desired location, without external power fields, in response to chemical signals in environmental media. We have developed a suitable steering mechanism to maintain the orientation of self-propelled droplets loaded with surfactant in fluidic environments. A spatial gradient of alkaline-earth metal ions induces directional sensing. These metal ions can be arranged in descending order of directional sensing as Ba(2+) ? Sr(2+) > Ca(2+) > Mg(2+). On the other hand, the affinity between metal ions and di-(2-ethylhexyl)phosphoric acid (DEHPA) decreases in the order as Ca(2+) > Ba(2+) > Sr(2+) > Mg(2+). To clarify the difference between the order of directional sensing and that of affinity, we investigated the effect of metal ions on the driving force to create asymmetric convection. We found that changes in the interfacial tension under nonequilibrium conditions play an important role in directional sensing. PMID:26000983

  10. Production and Applications of Metal-cluster-complex Ion Beams

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yukio; Kondou, Kouji; Teranishi, Yoshikazu; Watanabe, Kouji; Nonaka, Hidehiko; Saito, Naoaki; Itoh, Hiroshi; Fujimoto, Toshiyuki; Kurokawa, Akira; Ichimura, Shingo; Tomita, Mitsuhiro

    A new ion source using massive molecules called metal cluster complexes has been developed. Metal cluster complexes are chemically-synthesized organometallic compounds, which have a wide range of chemical compositions with high molecular weight. The ion source is compact enough to be installed in commonly used secondary ion mass spectrometry (SIMS) systems. Using the ion source, sputtering characteristics of silicon bombarded with normally incident Ir4(CO)7+ ions were investigated. Experimental results showed that the sputtering yield at 10 keV was 36, which is higher than that with Ar+ ions by a factor of 24. In addition, SIMS analyses of boron-delta-doped silicon samples and organic films of poly(methyl methacrylate) (PMMA) were performed. Compared with conventional O2+ ion beams, Ir4(CO)7+ ion beams improved depth resolution by a factor of 2.5 at the same irradiation conditions; the highest depth resolution of 0.9 nm was obtained at 5 keV, 45° with oxygen flooding of 1.3×10-4 Pa. Furthermore, experimental results confirmed that Ir4(CO)7+ ion beams significantly enhanced secondary ion intensity in high-mass region.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

    Bartsch, R.A.

    1994-12-31

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

  13. Titanates deliver metal ions to human monocytes.

    PubMed

    Wataha, John C; Hobbs, David T; Wong, Jacqueline J; Dogan, Sami; Zhang, Hai; Chung, K-H; Elvington, Mark C

    2010-04-01

    Amorphous peroxotitantes (APT) are insoluble titanium-based particles that bind a variety of metal compounds with high affinity; these particles could be sequestered locally in a solid phase to deliver metal-based drugs. Previous studies have confirmed the 'biodelivery' of metals from metal-APT complexes to fibroblasts, but not monocytes. Our goal in the current study was to use monocytic cytokine secretion to assess delivery of gold or platinum-based compounds from APT to human THP1 monocytes. Cytokine secretion was not triggered by APT alone or metal-APT complexes. In monocytes activated by lipopolysaccharide (LPS), APT alone enhanced or suppressed IL1beta or IL6 secretion, yet TNFalpha secretion was unaffected. Complexes of APT and Au(III) or cis-platin altered LPS-activated IL6 or IL1beta secretion most, TNFalpha least. Our results suggest that the APT deliver metals to monocytes. PMID:19941042

  14. Removal of metal ions from aqueous solution

    DOEpatents

    Jackson, Paul J. (Los Alamos, NM); Delhaize, Emmanuel (Los Alamos, NM); Robinson, Nigel J. (Durham, GB2); Unkefer, Clifford J. (Los Alamos, NM); Furlong, Clement (Seattle, WA)

    1990-01-01

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

  15. Removal of metal ions from aqueous solution

    DOEpatents

    Jackson, Paul J. (both Los Alamos, NM); Delhaize, Emmanuel (both Los Alamos, NM); Robinson, Nigel J. (Durham, GB2); Unkefer, Clifford J. (Los Alamos, NM); Furlong, Clement (Seattle, WA)

    1990-11-13

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

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

    DOEpatents

    Lundquist, Susan H. (White Bear Township, MN)

    2002-01-01

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

  17. Alkaline-earth metal phosphonocarboxylates: synthesis, structures, chirality, and luminescence properties.

    PubMed

    Zima, Vít?zslav; Raja, Duraisamy Senthil; Lee, Yu-Shan; Chang, Ting-Guang; Wu, Cheng-You; Hu, Chien-Chieh; Lee, Kueir-Rarn; Lai, Juin-Yih; Yeh, Jui-Ming; Lin, Chia-Her

    2013-11-21

    Six new alkaline-earth metal carboxyphosphonates [Mg(H2O)(H2PMIDA)] (1), [Sr(H2O)(H2PMIDA)] (2), [Sr2(H2O)(PMIDA)] (3), [Sr2(HPO4)(H2PMIDA)] (4), [Ba2(HPO4)(H2PMIDA)] (5), and [Ba2(H2O)(H2PMIDA)2] (6) (H4PMIDA = N-(phosphonomethyl)iminodiacetic acid) have been synthesized solvothermally in order to study the coordination behavior of H4PMIDA towards alkaline-earth metal ions (Mg(2+), Sr(2+), and Ba(2+)) and the structural features of the resulting polymeric compounds. The newly synthesized compounds have been characterized by elemental analysis, UV-Vis spectrometry, IR spectroscopy, thermogravimetry analysis, solid state (31)P MAS NMR, powder X-ray diffraction analysis and single crystal X-ray diffraction techniques. The single crystal structure analysis revealed structural variability of the prepared compounds. Compounds 1, 2, 4 and 5 are three-dimensional with the H2PMIDA skeletons connecting the inorganic parts to each other, whereas compound has a layered structure. Compounds 2, 4 and 5 contain helical structural motifs. In addition, the extrinsic luminescent properties of Eu(III)- and Tb(III)-doped compounds 1, 4 and 5 have also been studied. PMID:24002544

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

    PubMed Central

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

    2008-01-01

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

  19. Inference on the nature and the mass of Earth's late veneer from noble metals and gases

    E-print Network

    of extraterrestrial bodies struck the Earth after core formation and that comets comprised less than 10À3 by mass Objects: Comets; KEYWORDS: Bombardment, mass, nature, life, origin, Earth Citation: Dauphas, N., and BInference on the nature and the mass of Earth's late veneer from noble metals and gases Nicolas

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

    PubMed

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

    1988-02-17

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

  1. Metal ion binding and the folding of the hairpin ribozyme.

    PubMed Central

    Wilson, Timothy J; Lilley, David M J

    2002-01-01

    The hairpin ribozyme comprises two formally unpaired loops carried on two arms of a four-way helical RNA junction. Addition of divalent metal ions brings about a conformational transition into an antiparallel structure in which there is an intimate association between the loops to generate the active form of the ribozyme. In this study, we have used fluorescence resonance energy transfer to analyze the global folding of the complete ribozyme, and the simple four-way junction derived from it, over a wide concentration range of divalent and monovalent metal ions. The simple junction undergoes an ion-induced rotation into an antiparallel form. In the presence of a constant background concentration of sodium ions, the magnesium-ion-induced transition is characterized by noncooperative binding with a Hill coefficient n = 1. By contrast, the magnesium-ion-induced folding of the complete ribozyme is more complex, involving two distinct binding phases. The first phase occurs in the micromolar range, and involves the cooperative binding of at least three magnesium ions. This can also be achieved by high concentrations of sodium ions, and is therefore likely to be due to diffuse binding of cations at the junction and the interface of the loop-loop interaction. The second phase occurs in the millimolar range, and can only be induced by divalent metal ions. This transition occurs in response to the noncooperative, site-specific binding of magnesium ions. We observe a good correlation between the extent of ion-induced folding and cleavage activity. PMID:12022226

  2. Experimental determination of the partitioning of gallium between solid iron metal and synthetic basaltic melt Electron and ion microprobe study

    NASA Technical Reports Server (NTRS)

    Drake, M. J.; Newsom, H. E.; Reed, S. J. B.; Enright, M. C.

    1984-01-01

    The distribution of Ga between solid Fe metal and synthetic basaltic melt is investigated experimentally at temperatures of 1190 and 1330 C, and over a narrow range of oxygen fugacities. Metal-silicate reversal experiments were conducted, indicating a close approach to equilibrium. The analysis of the partitioned products was performed using electron and ion microprobes. At one bar total pressure, the solid metal/silicate melt partition coefficient D(Ga) is used to evaluate metal-silicate fractionation processes in the earth, moon, and Eucrite Parent Body (EPB). It is found that the depletion of Ga abundances in the EPB is due to the extraction of Ga into a metallic core. Likewise, the depletion of Ga in the lunar mantle is consistent with the extraction of Ga into a smaller lunar core if Ga was originally present in a subchondritic concentration. The relatively high Ga abundances in the earth's mantle are discussed, with reference to several theoretical models.

  3. Development of boron and phosphorus liquid metal ion sources for the focused ion beam system

    SciTech Connect

    Higuchi-Rusli, R.

    1986-01-01

    The approach taken here was to develop and build dual carbon filament liquid metal ion sources along with the test bed system. Pd/sub 73/B/sub 27/ and Pt/sub 58/B/sub 42/ binary alloys were selected as p-type dopant sources, and Cu/sub 3/P binary alloy was used as n-type dopant source. Three emitters with different tip radii were used in the present investigation. The results indicate that Pd/sub 73/B/sub 27/ alloy is a good candidate for a boron liquid metal ion source. This conclusion was derived in this investigation from a lifetime test result with 2.5 ..mu..m emitter of more than 120 hours. Pt/sub 58/B/sub 42/ alloy is not a suitable alloy source for a boron liquid metal ion source despite the higher mole fraction of boron to be used as a source of ionizing species. Cu/sub 3/P alloy is a good candidate for a phosphorus liquid metal ion source. Any apparent chemical interactions were found by metallographic technique, although AES result shows emitter element in the spectrum of collected beam current. A combination of rhenium and graphite ribbon as liquid metal ion source emitter and heater used in this investigation is the only possible approach to produce a long lifetime boron and phosphorus liquid metal ion source.

  4. Alkaline earth metal cation exchange: effect of mobile counterion and dissolved organic matter.

    PubMed

    Indarawis, Katrina; Boyer, Treavor H

    2012-04-17

    The goal of this research was to provide an improved understanding of the interactions between alkaline earth metals and DOM under conditions that are encountered during drinking water treatment with particular focus on cation exchange. Both magnetically enhanced and nonmagnetic cation exchange resins were converted to Na, Mg, Ca, Sr, and Ba mobile counterion forms as a novel approach to investigate the exchange behavior between the cations and the interactions between the cations and DOM. The results show that cation exchange is a robust process for removal of Ca(2+) and Mg(2+) considering competition with cations on the resin surface and presence of DOM. DOM was actively involved during the cation exchange process through complexation, adsorption, and coprecipitation reactions. In addition to advancing the understanding of ion exchange processes for water treatment, the results of this work are applicable to membrane pretreatment to minimize fouling, treatment of membrane concentrate, and precipitative softening. PMID:22424449

  5. Ion Irradiation-induced nano-crystallization metallic glasses (amorphous metal

    E-print Network

    Tran, Minh Hong

    2013-02-28

    This project idea is proposed in order to develop the understanding of the mechanisms responsible for Nano-crystal phase formation when metallic glasses (amorphous) is exposed under the high energy ion irradiation and is quantified the resulting...

  6. New type of metal ion source: Surface diffusion Li{sup +} ion source

    SciTech Connect

    Medvedev, V.K.; Suchorski, Y.; Block, J.H.

    1995-03-01

    A surface diffusion metal ion source, a new type of metal ion source, is explored. In this device a field desorption process is used to achieve an almost monoenergetic continuous flux of Li{sup +} ions from a [111]-oriented W field emitter. Earlier difficulties with the continuous supply of adatoms, required to produce measurable desorption rates, were overcome by making use of solid state surface diffusion from the Li multilayer reservoir at the shank of the field emitter. The high density of the ion beam (an ion current of 10{sup {minus}12} A was achieved from a W trimer), the extremely narrow energy distribution (full width at half-maximum of 0.25 eV) and the stable geometric form of the emitter itself during the operation are advantages of the new ion source which may be important in different areas of nanotechnology. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

  7. Membrane Interactions and Metal Ion Effects on Bilayer Permeation of the Lipophilic Ion Modulator DP-109

    E-print Network

    Jelinek, Raz

    are ascribed to interactions of the tested compounds with the phospholipid bilayers (11, 13-15). The colorMembrane Interactions and Metal Ion Effects on Bilayer Permeation of the Lipophilic Ion Modulator describe the application of a colorimetric phospholipid/ polydiacetylene (PDA) biomimetic membrane assay

  8. Rare-earth metal prices in the USA ca. 1960 to 1994

    USGS Publications Warehouse

    Hedrick, J.B.

    1997-01-01

    Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass, CA, USA, in 1949, was significant because it led to the production of commercial quantities of rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

  9. Rare-earth metal prices in the USA ca. 1960 to 1994

    USGS Publications Warehouse

    Hedrick, James B.

    1997-01-01

    Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass. CA, USA, in 1949, was significant because it led to the production of commercial quantities or rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

  10. A New Droplet Breakup Model for Dimer Ion Formation from a Gallium Liquid Metal Ion Source

    NASA Astrophysics Data System (ADS)

    Hornsey, Richard; Ishitani, Tohru

    1990-06-01

    It is demonstrated that energy distribution curves for Ga2+ found in the literature are inconsistent with existing models of cluster ion formation in liquid metal ion sources (LMIS). A new model for the rapid breakup of metastable droplets away from the emitting area is proposed to explain gallium dimer ion formation. Simple calculations are performed to establish the feasibility of this mechanism, and the practical application of this model is discussed in detail.

  11. Effective solvation of alkaline earth ions by proline-rich proteolytic peptides of galectin-3 upon electrospray ionisation.

    PubMed

    Lehmann, Wolf D; Wei, Junhua; Hung, Chien-Wen; Gabius, Hans-Joachim; Kirsch, Dieter; Spengler, Bernhard; Kübler, Dieter

    2006-01-01

    In an analysis of a combined chymotrypsin/AspN digest of galectin-3 by positive ion nano-electrospray ionisation mass spectrometry (nanoESI-MS) several peptides were observed which showed metal adduct ions as their most abundant ion signals. The most prominent adduct ions were observed at m/z values corresponding to [M+40]2+, [M+41]3+, and [M+42]4+ ions. Detailed investigation of the [M+40]2+ ion of the peptide GAPAGPLIVPY showed that it was not, as originally expected, a [M+H+39K]2+ adduct ion but had the composition [M+40Ca]2+. This was verified by several approaches: (i) nanoESI-MS/MS of the [M+Ca]2+ adduct ions resulted in the virtually exclusive formation of doubly charged fragment ions; (ii) mass determination by quadrupole time-of-flight (QTOF)-MS provided a preliminary identification; and (iii) accurate mass measurement using nanoESI Fourier transform ion cyclotron resonance (FTICR)-MS at a mass resolving power of 500 000 allowed the specific detection and identification of the isobaric ion pairs [M+40Ca]2+/[M+H+39K]2+ and [M+24Mg]2+/[M+H+23Na]2+. All peptides in the chymotryptic galectin-3 digest without a basic residue (K or R) showed addition of calcium as the most prominent ionisation principle. A further common feature of these nonbasic peptides was the presence of several proline residues, which is assumed to be a factor promoting the intense addition of calcium. It was observed that the common trace levels of sodium and calcium in analytical grade solvents (about 1-10 microM) are sufficient to generate the [M+H+23Na]2+ and [M+40Ca]2+ ions as the most prominent species of the peptide GAPAGPLIVPY. We conclude that the sequence motifs P-XX-P and P-XXX-P favour the solvation of alkaline earth ions in ESI-MS. In view of the successful detection of physiological Ca/protein interactions by ESI-MS, this finding may point to a solvation of Ca2+ by galectin in solution. The findings open new routes of research in the study of metal/protein and metal/peptide interactions PMID:16841364

  12. Metal ion levels and revision rates in metal-on-metal hip resurfacing arthroplasty: a comparative study.

    PubMed

    Robinson, Patrick G; Wilkinson, Andrew J; Meek, Robert M D

    2014-01-01

    Metal-on-metal (MoM) bearings in hip surgery are related to increased blood levels of metal ions. The nature of the relationship between ion levels and failure is still not fully understood. This study compares three cohorts of patients, 120 patients in each cohort, treated with a hip resurfacing arthroplasty, grouped by brand and diameter of femoral component on average four years postoperatively: Birmingham Hip Resurfacing ?50 mm, Durom resurfacing ?50 mm and Durom resurfacing <50 mm. The median blood ion levels of cobalt and chromium were significantly lower in the cohort with the large Durom resurfacing than the other two cohorts (P<0.05). The large BHR and large Durom HRA had revision rates of 3.3%. The small Durom HRA had a revision rate of 8.3%. Elevated blood ion levels can indicate a failing MoM bearing. The large BHR and large Durom HRA have similar revision rates yet the large Durom HRA had significantly lower metal ion levels. When similar ion levels were reported for BHR and small Durom the latter had significantly higher revision rates. This suggests ion levels do not absolutely predict the rate of HRA failure. Since MoM generation of metal ions is not the sole reason of failure, regular clinical and radiographic follow-up should also be in place for patients with these joints. PMID:24500833

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

    SciTech Connect

    Anders, A.

    1996-09-01

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

  14. Beam dynamics of a liquid-metal ion source

    NASA Astrophysics Data System (ADS)

    Whealton, J. H.; Meszaros, P. S.; Rothe, K. E.; Raridon, R. J.; Ryan, P. M.

    1990-01-01

    rms emittance growth of liquid-metal ion sources is studied. Processes included are nonlinear expansion through extractor and accelerator fringe fields, nonlinear beam space charge, plasma effects near needle, and waves [either ion acoustic or space charge limited as considered by Dudnikov (private communication, 1988)]. This investigation consists of 2-D analysis of appropriate Vlasov-Poisson equations in both steady-state and time-dependent formulations. Various geometries will be considered such as some used by Alton of ORNL.

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

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

    DOEpatents

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

    1999-08-10

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

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

    DOEpatents

    White, Lloyd R. (Minneapolis, MN); Lundquist, Susan H. (White Bear Township, MN)

    1999-01-01

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

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

    DOEpatents

    White, Lloyd R. (Minneapolis, MN); Lundquist, Susan H. (White Bear Township, MN)

    2000-01-01

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

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

    PubMed

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

    2010-09-15

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

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

    SciTech Connect

    Kondo, Kazuo; Sumi, Hisaharu; Matsumoto, Michiaki

    1996-07-01

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

  1. Improved scales for metal ion softness and toxicity.

    PubMed

    Kinraide, Thomas B

    2009-03-01

    Ten scales relating to chemical hardness or softness of metal ions were compiled. These included eight published scales such as those of Pearson, Ahrland, Klopman, and Misono. Another scale consisted of the logs of the solubility products of metal sulfides, and yet another was a consensus scale constructed from -log K values for metal ion binding to seven soft ligands. These 10 scales were normalized and averaged. The resulting consensus scale for softness (sigma(Con)) appeared to be superior to any of the 10 scales used in its construction based on correlations among the scales. Other possible indicators of softness were examined, including the standard electrode potential (E(0)) and the bulk metal density (rho(Metal)), both of which were also superior to most of the 10 scales just mentioned. Vales for sigma(Con) may be computed from E(0), rho(Metal), and the first ionization potential (I(P)), R(2) = 0.867, for the equation sigma(Con) = aE(0)I(P) + brho(Metal). A consensus scale for toxicity (T(Con)) derived from studies with many different taxa correlated well (R(2) = 0.807) with sigma(Con) computed from the preceding equation, but incorporation of ion charge (Z) into the following equation, T(Con) = asigma(Con) + bsigma(Con)Z + cZ, increased R(2) to 0.923. Substitution of other softness scales for sigma(Con) into equations to predict T(Con) reduced the value of R(2). Thus, sigma(Con) appears to be a superior scale for metal ion softness and toxicity, the latter being an interactive function of both softness and charge. PMID:18980392

  2. Oxygen and hydrogen ion abundance in the near-Earth magnetosphere: Statistical results on the response

    E-print Network

    Bergen, Universitetet i

    Oxygen and hydrogen ion abundance in the near-Earth magnetosphere: Statistical results investigate the oxygen-to-hydrogen ratio in the near-Earth magnetosphere from À10 RE , P. W. Daly, E. E. Grigorenko, L. M. Kistler, M. Fränz, and I. Dandouras (2012), Oxygen and hydrogen

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

    PubMed

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

    2008-02-01

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

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

    SciTech Connect

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

    2008-02-15

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

  5. Heavy metal ions are potent inhibitors of protein folding

    SciTech Connect

    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. Cd{sup 2+}, Hg{sup 2+} and Pb{sup 2+} 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{sub 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.

  6. Observation of doubly-charged dimer ion emission in liquid-metal-ion sources

    NASA Astrophysics Data System (ADS)

    Ishitani, T.; Umemura, K.; Kawanami, Y.

    1989-08-01

    Liquid-metal-ion sources (LMIS's) emit atomic and cluster ions. In the mass analysis of LMIS's using Au-Sb and Pt-Sb alloys, the doubly-charged dimer ions Sb 2+2 are observed as well as the doubly-charged diatomic ions AuSb 2+ and PtSb 2+. The flux abundance of Sb 2+2 in Sb + +Sb 2+2 for a Au-Sb alloy is approximately 20%, which is larger by one order of magnitude than that for a Pt-Au alloy. It is predicted that the stability of cluster ions is strongly affected by the electrostatic field near the ion emitter. The formation mechanism of M 2+2 ions is discussed using mass spectra and energy distribution curves.

  7. Pd and Ag metal-silicate partitioning applied to Earth differentiation and core-mantle exchange

    E-print Network

    Mcdonough, William F.

    Pd and Ag metal-silicate partitioning applied to Earth differentiation and core-mantle exchange metallic sulfide and liquid silicate under plausible magma ocean conditions constrains potential core 107 Ag content and the origin of observed Pd and Ag mantle abundances. DPd metallic sulfide / silicate

  8. MATERIALS WORLD January 201216 Dr Steve Barrett from the University of Liverpool, UK, has been studying rare earth metals for

    E-print Network

    Barrett, Steve D.

    studying rare earth metals for 20 years. Here he explains how preparation of the surface layer is crucial to the functionality of these scarce elements. S tudies into the properties of rare earth metals have been active since of the geometric and electronic structure of single crystal rare earth metal surfaces were published. Studies

  9. Dynamic polarizabilities of rare-earth-metal atoms and dispersion coefficients for their interaction with helium atoms

    E-print Network

    Chu, Xi

    Dynamic polarizabilities of rare-earth-metal atoms and dispersion coefficients; published 29 March 2007 The dynamic scalar and tensor polarizabilities of the rare-earth-metal atoms coefficients for the interactions of the rare-earth-metal atoms with helium atoms. The static polarizabilities

  10. Study of the rare-earth ion-acetylacetone-fumaric acid system by analysis of the complete NMR line shape

    SciTech Connect

    Khachatryan, A.S.; Vashchuk, A.V.; Mironov, V.L.

    1995-10-01

    The possibility of studying the paramagnetic rare-earth ion-acetylacetone-fumaric acid dynamic system by analysis of the complete NMR line shape is demonstrated within the formalism of a spin density matrix. The processes of three-position ligand exchange for the AB system of strongly coupled spins are simulated for the acid molecule at various concentrations of the metal and the ligands, rates of exchange, and limiting chemical shifts of protons in the heteroligand complexes. The calculated and experimental spectra are compared.

  11. Droplet and cluster ion emission from Ga and In liquid metal ion sources

    NASA Astrophysics Data System (ADS)

    Hornsey, Richard; Ishitani, Tohru

    1990-10-01

    There is at present a need to model the emission of droplets from liquid metal ion sources (LMIS), in order to account for such additional phenomena as cluster-ion emissions; knowledge of the droplets' initial sizes and droplets is required for the prediction of cluster ion voltage deficits. A simple model is developed in which the droplets are envisioned as forming from the breakoff of the tip sphere from the LMIS apical jet. The scheme is demonstrated to be useful in the derivation of qualitative variations of LMIS mass loss, Ga and In dimer ion voltage deficits, and energy spreads with current.

  12. A design of large current ion gun employing liquid metal ion source

    NASA Astrophysics Data System (ADS)

    Mori, Yuzo; Wang, Hui; Endo, Katsuyoshi; Yamauchi, Kazuto; Ide, Takashi

    1990-07-01

    A lens system for a large current liquid metal ion source has been designed by a numerical computer simulation method. As a computed result, the lens system can focus an ion beam having an emission angle of 60° to a beam having a radius of 1.8 mm at 1 m from the ion source. Following the simulated result, the lens system was constructed and tested. When the total ion current extracted from the ion source was less than 10 ?A, more than 95% of the total ion was focused to a beam with a radius of about 2 mm at 1 m from the ion source, which agreed well with the computer simulation result. When the total ion current became more than 10 ?A, the minimum radius of the focused ion beam at 1 m from the ion source gradually increased with it. However, even if the total ion current was more than 50 ?A, almost 80% of it could be obtained on a 1×1 cm2 target at 1 m from the ion source.

  13. Metal ion bombardment of onion skin cell wall

    SciTech Connect

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

    2004-05-10

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

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

    PubMed

    Vincent, Thierry; Vincent, Chloë; Guibal, Eric

    2015-01-01

    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. PMID:26610439

  15. How do energetic ions damage metallic surfaces?

    DOE PAGESBeta

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

    2015-02-20

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

  16. Changes in blood ion levels after removal of metal-on-metal hip replacements

    PubMed Central

    Durrani, Salim K; Sampson, Barry; Panetta, Therese; Liddle, Alexander D; Sabah, Shiraz A; Chan, Newton K; Skinner, John A; Hart, Alister J

    2014-01-01

    Background and purpose In patients with metal-on-metal (MoM) hip prostheses, pain and joint effusions may be associated with elevated blood levels of cobalt and chromium ions. Since little is known about the kinetics of metal ion clearance from the body and the rate of resolution of elevated blood ion levels, we examined the time course of cobalt and chromium ion levels after revision of MoM hip replacements. Patients and methods We included 16 patients (13 female) who underwent revision of a painful MoM hip (large diameter, modern bearing) without fracture or infection, and who had a minimum of 4 blood metal ion measurements over an average period of 6.1 (0–12) months after revision. Results Average blood ion concentrations at the time of revision were 22 ppb for chromium and 43 ppb for cobalt. The change in ion levels after revision surgery varied extensively between patients. In many cases, over the second and third months after revision surgery ion levels decreased to 50% of the values measured at revision. Decay of chromium levels occurred more slowly than decay of cobalt levels, with a 9% lag in return to normal levels. The rate of decay of both metals followed second-order (exponential) kinetics more closely than first-order (linear) kinetics. Interpretation The elimination of cobalt and chromium from the blood of patients who have undergone revision of painful MoM hip arthroplasties follows an exponential decay curve with a half-life of approximately 50 days. Elevated blood levels of cobalt and chromium ions can persist for at least 1 year after revision, especially in patients with high levels of exposure. PMID:24758321

  17. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

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

    1983-05-13

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

  18. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

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

    1981-11-04

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

  19. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, Toshifumi (Mastic Beach, NY); Kukacka, Lawrence E. (Port Jefferson, NY); Horn, William H. (Brookhaven, NY)

    1985-01-01

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

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

    SciTech Connect

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

    1990-07-01

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

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

    SciTech Connect

    Nicholas B. Lentz

    2007-12-01

    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 [Gln{sup 11}]-amyloid {beta}-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 become routine tomorrow.

  2. A study of the formation and dynamics of the Earth's plasma sheet using ion composition data

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.

    1994-01-01

    Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.

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

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

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

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

    DOEpatents

    Lundquist, Susan H. (White Bear Township, MN); White, Lloyd R. (Minneapolis, MN)

    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.

  5. Metal ion influence on eumelanin fluorescence and structure

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    SciTech Connect

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

    2015-04-08

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  9. Metal negative ion production by an RF sputter self-extraction ion source

    NASA Astrophysics Data System (ADS)

    Yamada, N.; Kasuya, T.; Kenmotsu, T.; Vasquez, M. R., Jr.; Wada, M.

    2013-02-01

    An 80 mm diameter 80 mm long RF sputter type self-extraction negative ion source equipped with a metal sputter target has been tested to investigate the performance of producing beams of negative aluminum (Al) ions. An RF power at 13.56 MHz is directly supplied to a 60 mm diameter target containing a cylindrical and ring permanent magnets to form planar magnetron magnetic field geometry. The target is self-biased to a DC potential at about -250 V with respect to the plasma, and negative ions produced at the surface are self-extracted from the target across the sheath to reach the ion beam extraction hole. Injection of cesium into the discharge enhanced the amount of Al- ions but it also enlarged the impurity ion beam current.

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

    DOEpatents

    Clark, Jr., William M. (Thousand Oaks, CA); Utlaut, Mark W. (Saugus, CA); Wysocki, Joseph A. (Oxnard, CA); Storms, Edmund K. (Los Alamos, NM); Szklarz, Eugene G. (Los Alamos, NM); Behrens, Robert G. (Los Alamos, NM); Swanson, Lynwood W. (McMinnville, OR); Bell, Anthony E. (McMinnville, OR)

    1987-06-02

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

  11. New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

    SciTech Connect

    Alexandra Navrotsky; Mary Lou Balmer; Tina M. Nenoff; Yali Su

    2003-12-05

    This renewal proposal outlines our current progress and future research plans for ion exchangers: novel metal niobate and silicotitanate ion exchangers and their ultimate deployment in the DOE complex. In our original study several forms (including Cs exchanged) of the heat treated Crystalline Silicotitanates (CSTs) were fully characterized by a combination of high temperature synthesis and phase identification, low temperature synthesis and phase identification, and thermodynamics. This renewal proposal is predicated on work completed in our current EMSP program: we have shown preliminary data of a novel class of niobate-based molecular sieves (Na/Nb/M/O, M = transition metals), which show exceptionally high selectivity for divalent cations under extreme conditions (acid solutions, competing cations), in addition to novel silicotitanate phases which are also selective for divalent cations. Furthermore, these materials are easily converted by a high temperature in-situ heat treatment into a refractory ceramic waste form with low cation leachability. The new waste form is a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of HLW wastes from reprocessed, spent nuclear fuel. These new niobate ion exchangers also shown orders of magnitude better selectivity for Sr2+ under acid conditions than any other material. The goal of the program is to reduce the costs associated with divalent cation waste removal and disposal, to minimize the risk of contamination to the environment during ion exchanger processing, and to provide DOE with materials for near-term lab-bench stimulant testing, and eventual deployment. The proposed work will provide information on the structure/property relationship between ion exchanger frameworks and selectivity for specific ions, allowing for the eventual ''tuning'' of framework for specific ion exchange needs. To date, DOE sites have become interested in on-site testing of these materials; ongoing discussions and initial experiments are occurring with Dr. Dean Peterman, Idaho National Engineering and Environmental Laboratory (INEEL) (location of the DOE/EM Waste Treatment Focus Area), and Dr. John Harbour, Savannah River Site (SRS). Yet the materials have not been optimized, and further research and development of the novel ion exchangers and testing conditions with simulants are needed. In addition, studies of the ion exchanger composition versus ion selectivity, ion exchange capacity and durability of final waste form are needed. This program will bring together three key institutions to address scientific hurdles of the separation process associated with metal niobate and silicotitanate ion exchangers, in particular for divalent cations (e.g., Sr2+). The program involves a joint effort between researchers at Pacific Northwest National Laboratory, who are leaders in structure/property relations in silicotitanates and in waste form development and performance assessment, Sandia National Laboratories, who discovered and developed crystalline silicotitanate ion exchangers (with Texas A&M and UOP) and also the novel class of divalent metal niobate ion exchangers, and the Thermochemistry Facility at UC Davis, who are world renowned experts in calorimetry and have already performed extensive thermodynamic studies on silicotitanate materials. In addition, Dr. Rodney Ewing of University of Michigan, an expert in radiation effects on materials, and Dr. Robert Roth of the National Institute of Standards and Technology and The Viper Group, a leader in phase equilibria development, will be consultants for radiation and phase studies. The research team will focus on three tasks that will provide both the basic research necessary for the development of highly selective ion exchange materials and also materials for short-term deployment within the DOE complex: (1) Structure/property relationships of a novel class of niobate-based molecular sieves (Na/Nb/M/O, M = transition metals), which show exceptionally high selectivity for divalent cations un

  12. Principles Governing Metal Ion Selectivity in Ion Channel Proteins

    NASA Astrophysics Data System (ADS)

    Lim, Carmay

    2014-03-01

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

  13. SIMS depth profile study using metal cluster complex ion bombardment

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    SIMS depth profiles using a metal cluster complex ion of Ir4 (CO)7+were studied. An unusual increase of the sputtering yield under the condition of small incident angle may be attributed to the suppression of taking oxygen from flooding O2 by the formation of a carbon cover-layer derived from Ir4 (CO)7+ion. Even though the roughness of the sputtered surface is small, the depth resolution was not improved by decreasing the cluster ion energy to less than 5 keV, because the carbon cover-layer prevents the formation of surface oxide that buffers atomic mixing. To overcome this issue, it will be necessary to eliminate carbon from the cluster ion.

  14. Exploration of metal ion binding sites in RNA folds by Brownian-dynamics simulations

    E-print Network

    Westhof, Eric

    Exploration of metal ion binding sites in RNA folds by Brownian- dynamics simulations Thomas Hermann and Eric Westhof* Background: Metal ions participate in the three-dimensional folding of RNA and provide active centers in catalytic RNA molecules. The positions of metal ions are known for a few RNA

  15. Three metal ions at the active site of the Tetrahymena group I ribozyme

    E-print Network

    Herschlag, Dan

    Three metal ions at the active site of the Tetrahymena group I ribozyme Shu-ou Shan*, Aiichiro, CO, August 27, 1999 (received for review May 13, 1999) Metal ions are critical for catalysis by many RNA and protein enzymes. To understand how these enzymes use metal ions for catalysis, it is crucial

  16. Process for preparing higher oxides of the alkali and alkaline earth metals

    NASA Technical Reports Server (NTRS)

    Sadhukhan, P.; Bell, A. (inventors)

    1978-01-01

    High purity inorganic higher oxides of the alkali and alkaline earth metals are prepared by subjecting the hydroxide of the alkali and alkaline earth metal to a radio frequency discharge sustained in oxygen. The process is particulary adaptable to the production of high purity potassium superoxide by subjecting potassium hydroxide to glow discharge sustained in oxygen under the pressure of about 0.75 to 1.00 torr.

  17. Minerals yearbook, 1989: Rare-earth minerals and metals

    SciTech Connect

    Hedrick, J.B.; Templeton, D.A.

    1989-01-01

    Domestic consumption of the rare earths was almost double the quantity used in 1988, mine production increased sharply, and the industry performed well amid increased international competition. Traditional markets of the rare earths, such as petroleum catalysts and metallurgical additives, continued a downward trend while new and emerging markets, such as neodymium-iron-boron permanent magnets, advanced ceramics, and automotive catalysts, showed strong growth. The television and lamp phosphors market was unchanged, and glass polishing applications increased markedly. Demand for rare earths consumed in high-temperature superconductors was small; however, technologic breakthroughs in 1989 increased the prospects for commercial development of rare-earth superconductors.

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

    SciTech Connect

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

    1987-09-01

    We consider the charge state distribution of ions produced in the metal vapor vacuum arc plasma discharge. A new kind of high current metal ion source in which the ion beam is extracted from a metal vapor vacuum arc plasma has been used to obtain the spectra of multiply charged ions produced within the cathode spots. The cathode materials used and the species reportetd on here are: C, Mg, Al, Si, Ti, Cr, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Rh, Pd, Ag, In, Sn, Gd, Ho, Ta, W, Pt, Au, Pb, Th, and U; the arc current was 200 A for all measurements. Charge state spectra were measured using a time-of-flight method. The arc voltage was also measured. In this paper we report on the measured charge state distributions and arc voltages and compare the distributions with the predictions of a theory in which ionization occurs in the cathode spots via stepwise ionization by electron impact. 64 refs., 10 figs., 3 tabs.

  19. Detection of singly ionized energetic lunar pick-up ions upstream of earth's bow shock

    NASA Technical Reports Server (NTRS)

    Hilchenbach, M.; Hovestadt, D.; Klecker, B.; Moebius, E.

    1992-01-01

    Singly ionized suprathermal ions upstream of the earth's bow shock have been detected by using the time-of-flight spectrometer SULEICA on the AMPTE/IRM satellite. The data were collected between August and December 1985. The flux of the ions in the mass range between 23 and 37 amu is highly anisotropic towards the earth. The ions are observed with a period of about 29 days around new moon (+/- 3 days). The correlation of the energy of the ions with the solar wind speed and the interplanetary magnetic field orientation indicates the relation to the pick-up process. We conclude that the source of these pick-up ions is the moon. We argue that due to the impinging solar wind, atoms are sputtered off the lunar surface, ionized in the sputtering process or by ensuing photoionization and picked up by the solar wind.

  20. New Catalytic DNA Biosensors for Radionuclides and Metal ion

    SciTech Connect

    Yi Lu

    2008-03-01

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

  1. High Pressure Phase Transformations in Heavy Rare Earth Metals and Connections to Actinide Crystal Structures

    SciTech Connect

    Vohra, Yogesh K.; Sangala, Bagvanth Reddy; Stemshorn, Andrew K.; Hope, Kevin M.

    2008-07-01

    High-pressure studies have been performed on heavy rare earth metals Terbium (Tb) to 155 GPa and Holmium (Ho) to 134 GPa in a diamond anvil cell at room temperature. The following crystal structure sequence was observed in both metals hcp {yields} Sm-type {yields} dhcp {yields} distorted fcc (hR-24) {yields} monoclinic (C2/m) with increasing pressure. The last transformation to a low symmetry monoclinic phase is accompanied by a volume collapse of 5 % for Tb at 51 GPa and a volume collapse of 3 % for Ho at 103 GPa. This volume collapse under high pressure is reminiscent of f-shell delocalization in light rare earth metal Cerium (Ce), Praseodymium (Pr), and heavy actinide metals Americium (Am) and Curium (Cm). The orthorhombic Pnma phase that has been reported in Am and Cm after f-shell delocalization is not observed in heavy rare earth metals under high pressures. (authors)

  2. Polymer filtration systems for dilute metal ion recovery

    SciTech Connect

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

    1998-12-01

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

  3. Ion beam sputter-deposited thin film coatings for protection of spacecraft polymers in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Mirtich, M. J.; Rutledge, S. K.; Swec, D. M.; Nahra, H. K.

    1985-01-01

    Ion beam sputter-deposited thin films of Al2O3, SiO2, and a codeposited mixture of predominantly SiO2 with small amounts of a fluoropolymer were evaluated both in laboratory plasma ashing tests and in space on board shuttle flight STS-8 for effectiveness in preventing oxidation of polyimide Kapton. Measurements of mass loss and optical performance of coated and uncoated polyimide samples exposed to the low Earth orbital environment are presented. Optical techniques were used to measure loss rates of protective films exposed to atomic oxygen. Results of the analysis of the space flight exposed samples indicate that thin film metal oxide coatings are very effective in protecting the polyimide. Metal oxide coatings with a small amount of fluoropolymer codeposited have the additional benefit of great flexibility.

  4. Ion beam sputter-deposited thin film coatings for protection of spacecraft polymers in low earth orbit

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Mirtich, M. J.; Rutledge, S. K.; Swec, D. M.; Nahra, H. K.

    1985-01-01

    Ion beam sputter-deposited thin films at Al2O3, SiO2, and a codeposited mixture of predominantly SiO2 with small amounts of fluoropolymer were evaluated both in laboratory plasma ashing tests and in space on board Shuttle flight STS-8 for effectiveness in preventing oxidation of polyimide Kapton. Measurements of mass loss and optical performance of coated and uncoated polyimide samples exposed to the low earth orbital environment are presented. Optical techniques were used to measure loss rates of protective films exposed to atomic oxygen. Results of the analysis of the space flight exposed samples indicate that thin film metal oxide coatings are very effective in protecting the polyimide. Metal oxide coatings with a small amount of fluoropolymer codeposited have the additional benefit of great flexibility.

  5. Beam dynamics of a liquid metal ion source

    SciTech Connect

    Whealton, J.H.; Meszaros, P.S.; Rothe, K.E.; Raridon, R.J.; Ryan, P.M.

    1989-01-01

    RMS emittance growth of liquid metal ion sources is studied. Processes included are nonlinear expansion through extractor and accelerator fringe fields, nonlinear beam space charge, plasma effects near needle, and waves (either ion-acoustic or space charge limited as considered by V.I. Dudnikov). This investigation consists of 2-D analysis of appropriate Vlasov-Poisson equations in both steady-state and time-dependent formulations. Various geometries will be considered such as some used by G. Alton of ORNL. 2 refs., 7 figs.

  6. The electromagnetic ion beam instability upstream of the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Gary, S. P.; Gosling, J. T.; Forslund, D. W.

    1981-01-01

    The linear theory of the electromagnetic ion beam instability for arbitrary angles of propagation has been studied. The parameters considered in the theory are typical of the solar wind upstream of the earth's bow shock when a 'reflected' proton beam is present. Maximum growth occurs for propagation parallel to the ambient magnetic field B, but this instability also displays significant growth at wave-vectors oblique to B. Oblique, unstable modes seem to be the likely source of the compressive magnetic fluctuations recently observed in conjunction with the 'diffuse' ion population. An energetic ion beam does not directly give rise to linear growth of either ion acoustic or whistler mode instabilities.

  7. Magnetic exchange interaction between rare-earth and Mn ions in multiferroic hexagonal manganites

    SciTech Connect

    Talbayev, Diyar; Trugman, Stuart A; Taylor, Antoinette J; Averitt, Richard D; Namjung, Hur; Andrew, Laforge D; Dimitri, Basov N

    2008-01-01

    The authors report a study of magnetic dynamics in multiferroic hexagonal manganite HoMnO{sub 3} by far-infrared spectroscopy. Low-temperature magnetic excitation spectrum of HoMnO{sub 3} consists of magnetic-dipole transitions of Ho ions within the crystal-field split J = 8 manifold and of the triangular antiferromagnetic resonance of Mn ions. They determine the effective spin Hamiltonian for the Ho ion ground state. The magnetic-field splitting of the Mn antiferromagnetic resonance allows us to measure the magnetic exchange coupling between the rare-earth and Mn ions.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1993-01-01

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

  10. Interactions of metal ions with ? synuclein and amyloid ? peptides

    NASA Astrophysics Data System (ADS)

    Valensin, Daniela; Kozlowski, Henryk; Tessari, Isabella; Dell'Acqua, Simone; Bubacco, Luigi; Casella, Luigi; Gaggelli, Elena; Valensin, Gianni

    2014-10-01

    Amyloid ? (A?) and alfa synuclein (?S) share the ability to selectively bind copper ions (Cu(II) and Cu(I)). During the last decade large efforts have been directed to fully characterize Cu(II) binding domains in A? and ?S. On the other hand, the corresponding Cu(I) sites have been less considered. In this study we have analyzed Cu(I) interactions with peptides derived from A? and ?S, by means of CD and NMR spectroscopy. Beyond Cu(I), we have also used Ag(I) as a probe. By monitoring the metal induced effects on ?S and A? systems, the Cu(I)/Ag(I) binding domains have been identified. The corresponding protein structural rearrangements induced by the metal ions have been investigated as well. The Cu(I) coordination spheres are discussed with a particular emphasis to the role played by Met and His residues.

  11. A metallic room-temperature oxide ion conductor.

    PubMed

    Heise, Martin; Rasche, Bertold; Isaeva, Anna; Baranov, Alexey I; Ruck, Michael; Schäfer, Konrad; Pöttgen, Rainer; Eufinger, Jens-Peter; Janek, Jürgen

    2014-07-01

    Nanoparticles of Bi3 Ir, obtained from a microwave-assisted polyol process, activate molecular oxygen from air at room temperature and reversibly intercalate it as oxide ions. The closely related structures of Bi3 Ir and Bi3 IrOx (x?2) were investigated by X-ray diffraction, electron microscopy, and quantum-chemical modeling. In the topochemically formed metallic suboxide, the intermetallic building units are fully preserved. Time- and temperature-dependent monitoring of the oxygen uptake in an oxygen-filled chamber shows that the activation energy for oxide diffusion (84?meV) is one order of magnitude smaller than that in any known material. Bi3 IrOx is the first metallic oxide ion conductor and also the first that operates at room temperature. PMID:24866268

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

    SciTech Connect

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

    2013-12-15

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

  13. Metal ions: supporting actors in the playbook of small ribozymes.

    PubMed

    Johnson-Buck, Alexander E; McDowell, Sarah E; Walter, Nils G

    2011-01-01

    Since the 1980s, several small RNA motifs capable of chemical catalysis have been discovered. These small ribozymes, composed of between approximately 40 and 200 nucleotides, have been found to play vital roles in the replication of subviral and viral pathogens, as well as in gene regulation in prokaryotes, and have recently been discovered in noncoding eukaryotic RNAs. All of the known natural small ribozymes - the hairpin, hammerhead, hepatitis delta virus, Varkud satellite, and glmS ribozymes--catalyze the same self-cleavage reaction as RNase A, resulting in two products, one bearing a 2'-3' cyclic phosphate and the other a 5'-hydroxyl group. Although originally thought to be obligate metalloenzymes like the group I and II self-splicing introns, the small ribozymes are now known to support catalysis in a wide variety of cations that appear to be only indirectly involved in catalysis. Nevertheless, under physiologic conditions, metal ions are essential for the proper folding and function of the small ribozymes, the most effective of these being magnesium. Metal ions contribute to catalysis in the small ribozymes primarily by stabilizing the catalytically active conformation, but in some cases also by activating RNA functional groups for catalysis, directly participating in catalytic acid-base chemistry, and perhaps by neutralizing the developing negative charge of the transition state. Although interactions between the small ribozymes and cations are relatively nonspecific, ribozyme activity is quite sensitive to the types and concentrations of metal ions present in solution, suggesting a close evolutionary relationship between cellular metal ion homeostasis and cation requirements of catalytic RNAs, and perhaps RNA in general. PMID:22010272

  14. Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

    E-print Network

    Guise, Nicholas D; Tan, Joseph N

    2013-01-01

    A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning tra...

  15. The Morphology of Ring Current He-Ions in Earth’s Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Gerrard, Andrew; Cusanelli, Jessie; Lanzerotti, Louis

    2015-04-01

    The Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument on the Van Allan Probes makes unique measurements of, among other ring current species, He-ions in the ~65-keV to ~520-keV energy range. In this paper we report on the spatial “double belt” structure of ring current He-ions as measured on both spacecraft during quiet and active magnetic conditions. Specifically, we show the 3D structures of both the low L-shell, high energy and high L-shell, low energy populations at all magnetic local times. We also present the first ring current measurements of He-ions above ~520-keV, which were obtained in a modified RBSPICE operation mode. These high energy He-ions appear to be modulated by ionospheric-controlled electric field variability, as was suggested in earlier modeling efforts.

  16. Novel polymerization catalysts and hydride clusters from rare-earth metal dialkyls

    NASA Astrophysics Data System (ADS)

    Nishiura, Masayoshi; Hou, Zhaomin

    2010-04-01

    This Review gives an overview on recent progress in the synthesis and chemistry of rare-earth metal dialkyl complexes bearing monoanionic ancillary ligands, with an emphasis on novel polymerization catalysts. These structurally well-defined and highly reactive compounds are prepared either by alkane elimination reactions between trialkyl rare-earth complexes and acidic neutral ligands, or by the metathetical reactions of rare-earth trihalides with the alkali metal salts of the corresponding ligands. On treatment with an appropriate borate compound, the dialkyl complexes are converted into the corresponding cationic monoalkyl species, which serve as excellent catalysts for the polymerization and copolymerization of a variety of olefins to yield a series of new polymer materials that exhibit novel properties. Alternatively, hydrogenation of the dialkyl rare-earth complexes with H2 affords a new class of rare-earth polyhydride complexes with unique features in terms of both their structure and reactivity.

  17. MRI findings following metal on metal hip arthroplasty and their relationship with metal ion levels and acetabular inclination angles.

    PubMed

    Fox, Ciara M; Bergin, Karen M; Kelly, Gabrielle E; McCoy, Gerry F; Ryan, Anthony G; Quinlan, John F

    2014-08-01

    Following the global recall of all ASR metal on metal hip products, our aim was to correlate MRI findings with acetabular inclination angles and metal ion levels in patients with these implants. Both cobalt and chromium levels were significantly higher in the presence of a periprosthetic fluid collection. There was no association between the presence of a periprosthetic mass, bone marrow oedema, trochanteric bursitis or greater levels of abductor muscle destruction for cobalt or chromium. There was no association between the level of periprosthetic tissue reaction and the acetabular inclination angle with any of the pathologies identified on MRI. The relationship between MRI pathology, metal ion levels and acetabular inclination angles in patients with ASR implants remains unclear adding to the complexity of managing patients. PMID:24793890

  18. Nanostructure operations by means of the liquid metal ion sources.

    PubMed

    Gasanov, I S; Gurbanov, I I

    2012-02-01

    Characteristics of a disperse phase of liquid metal ion source on the basis of various working substances are investigated. It is revealed that generation of the charged particles occurs in the threshold image and is simultaneously accompanied by excitation of capillary instability on a surface of the emitter. The majority of particles has the size about 2 nm (Sn) and a specific charge of 5 × 10(4) C?kg. If the working liquid possesses high viscosity (Ni), generation of nanodroplets does not occur. Gold nanoparticles are used for deposition on a surface of quartz cantilevers with the purpose of increase in sensitivity of biosensors and on an external surface of carbon nanotubes for creation pressure sensors. By means of an ion source nanostructures can be etched on a flat surface of conductive materials without difficult ion optics. PMID:22380338

  19. Reservoir-type liquid metal ion source of Al

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroshi; Torii, Yasuhiro

    1986-07-01

    A liquid metal ion source of Al with a boride reservoir was developed. In this reservoir a shorter boride emitter was designed to overcome the brittleness of boride materials and some problems in supplying the Al material. This source makes possible a long continuous operation time and enhanced reliability. The fundamental performance characteristics did not change after 250 h of operation. A stable Al ion beam emission was obtained for more than 500 h and its current fluctuation was less than ±1%/3 h for a 20-30-?A source ion current. The energy spread was less than 9 eV (FWHM) for a 30-?A/sr angular current intensity.

  20. Energization of Ions in near-Earth current sheet disruptions

    NASA Technical Reports Server (NTRS)

    Taktakishvili, A.; Lopez, R. E.; Goodrich, C. C.

    1995-01-01

    In this study we examine observations made by AMPTE/CCE of energetic ion bursts during seven substorm periods when the satellite was located near the neutral sheet, and CCE observed the disruption cross-tail current in situ. We compare ion observations to analytic calculations of particle acceleration. We find that the acceleration region size, which we assume to be essentially the current disruption region, to be on the order of 1 R(sub E). Events exhibiting weak acceleration had either relatively small acceleration regions (apparently associated with pseudobreakup activity on the ground) or relatively small changes in the local magnetic field (suggesting that the magnitude of the local current disruption region was limited). These results add additional support for the view that the particle bursts observed during turbulent current sheet disruptions are due to inductive acceleration of ions.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  2. In vivo liberation of silver ions from metallic silver surfaces.

    PubMed

    Danscher, Gorm; Locht, Linda Jansons

    2010-03-01

    In vivo liberation of electrically charged silver atoms/silver ions from metallic silver pellets, silver grids and silver threads placed in the brain, skin and abdominal cavity was proved by way of the histochemical technique autometallography (AMG). A bio-film or "dissolution membrane" inserted between the metallic surface and macrophages was recognized on the surface of the implanted silver after a short period of time. Bio-released silver ions bound in silver-sulphur nanocrystals were traced within the first 24 h in the "dissolution membrane" and the "dissolucytotic" macrophages. In animals that had survived 10 days or more, silver nanocrystals were detected both extra- and intracellularly in places far away from the implant including regional lymph nodes, liver, kidneys and the central nervous system (CNS). The accumulated silver was always confined to lysosome-like organelles. Dissolucytotic silver was extracellularly related to collagen fibrils and fibres in connective tissue and basement membranes. Our study demonstrates that (1) the number of bio-released silver ions depends on the size of the surface of the implanted silver, (2) the spread of silver ions throughout the body takes place primarily not only through the vascular system, but also by retrograde axonal transport. It is concluded that implantation of silver or silver-plated devices is not recommendable. PMID:20033701

  3. Ion distributions in the Earth's foreshock upstream from the bow shock

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.

    1995-01-01

    A variety of suprathermal and energetic ion distributions are found upstream from shocks. Some distributions, such as field-aligned beams, are generated directly at the shock either through reflection processes or through leakage from the hotter downstream region. Other distributions, such as intermediate distributions, evolve from these parent distributions through wave-particle interactions. This paper reviews our current understanding of the creation and evolution of suprathermal distributions at shocks. Examples of suprathermal ion distributions are taken from observations at the Earth's bow shock. Particular emphasis is placed on the creation of field-aligned beams and specularly reflected ion distributions and on the evolution of these distributions in the Earth's ion foreshock. However, the results from this heavily studied region are applicable to interplanetary shocks, bow shocks at other planets, and comets.

  4. Long-life bismuth liquid metal ion source for focussed ion beam micromachining application

    NASA Astrophysics Data System (ADS)

    Mazarov, P.; Melnikov, A.; Wernhardt, R.; Wieck, A. D.

    2008-09-01

    Liquid metal ion sources (LMISs) with Ga as ion species are widely used in focused ion beam (FIB) technology for micromachining and surface treatment on the sub-micron and nano-scale. Key features of a LMIS for investigating mechanical properties and 3D-microfabrication of materials are long life-time, high brightness, stable ion current and a highly effective milling ability for the material to be modified. In order to increase the material removal rate, heavier ions than Ga and their clusters should be applied. Bismuth (Bi) is the heaviest, non-radio-active element in the periodic table, is non-toxic and exhibits a low melting point. We have thus produced a long-life (about 1000 h) Bi LMIS with a good beam performance, applicable in any FIB system. Since Bi is the only element in this source, it is not necessary to separate it from other ions by a mass filter. Investigation of the sputtering rate of NiTi shape memory alloys using Ga and Bi LMIS showed that, for the same experimental conditions, the material removal rate with using of Bi nk+ ions in a standard FIB machine without a mass separator is about five times larger compared to Ga + ions. This use of Bi as LMIS-species is the ultimate breakthrough in sputtering applications.

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

    PubMed

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

    2015-12-15

    Many dsDNA viruses encode DNA-packaging terminases, each containing a nuclease domain that resolves concatemeric DNA into genome-length units. Terminase nucleases resemble the RNase H-superfamily nucleotidyltransferases in folds, and share a two-metal-ion catalytic mechanism. Here we show that residue K428 of a bacteriophage terminase gp2 nuclease domain mediates binding of the metal cofactor Mg(2+). A K428A mutation allows visualization, at high resolution, of a metal ion binding mode with a coupled-octahedral configuration at the active site, exhibiting an unusually short metal-metal distance of 2.42 Å. Such proximity of the two metal ions may play an essential role in catalysis by generating a highly positive electrostatic niche to enable formation of the negatively charged pentacovalent phosphate transition state, and provides the structural basis for distinguishing Mg(2+) from Ca(2+). Using a metal ion chelator ?-thujaplicinol as a molecular probe, we observed a second mode of metal ion binding at the active site, mimicking the DNA binding state. Arrangement of the active site residues differs drastically from those in RNase H-like nucleases, suggesting a drifting of the active site configuration during evolution. The two distinct metal ion binding modes unveiled mechanistic details of the two-metal-ion catalysis at atomic resolution. PMID:26450964

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    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

    2014-01-01

    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 detrimental effects on bone. It is unknown whether serum metal ion levels affect bone density clinically. We compared cementless large femoral head (mean 48 mm) metal-on-metal total hip arthroplasties (M2a-Magnum, Biomet) to cementless 28 mm metal-on-polyethylene total hip arthroplasties (Mallory-Head, Biomet) in a randomised clinical trial. We evaluated periprosthetic acetabular bone density and serum metal ion levels at 1 year postoperatively. Acetabular bone density was analyzed with dual energy x-ray absorptiometry in four horizontal regions of interest in 70 patients. After one year, acetabular bone density decreased (-3.5% to -7.8%) in three of four regions of interest in metal-on-polyethylene patients, but was retained in metal-on-metal patients. Bone density preservation was most pronounced superior to the metal-on-metal cup (+1% versus -3.7%). Serum cobalt, chromium and titanium ion levels were not related to bone density, nor to acetabular inclination or femoral head size. Oxford and Harris hip scores were similar in both groups. Contrary to our hypothesis, acetabular bone density was retained with metal-on-metal total hip arthroplasty, compared to metal-on-polyethylene arthroplasty. Bone preservation was most pronounced in the area superior to the cup. This could be a benefit during future revision surgery. PMID:24186673

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

    PubMed

    Cook, Sarah A; Borovik, A S

    2015-08-18

    The functions of metal complexes are directly linked to the local environment in which they are housed; modifications to the local environment (or secondary coordination sphere) are known to produce changes in key properties of the metal centers that can affect reactivity. Noncovalent interactions are the most common and influential forces that regulate the properties of secondary coordination spheres, which leads to complexities in structure that are often difficult to achieve in synthetic systems. Using key architectural features from the active sites of metalloproteins as inspiration, we have developed molecular systems that enforce intramolecular hydrogen bonds (H-bonds) around a metal center via incorporation of H-bond donors and acceptors into rigid ligand scaffolds. We have utilized these molecular species to probe mechanistic aspects of biological dioxygen activation and water oxidation. This Account describes the stabilization and characterization of unusual M-oxo and heterobimetallic complexes. These types of species have been implicated in a range of oxidative processes in biology but are often difficult to study because of their inherent reactivity. Our H-bonding ligand systems allowed us to prepare an Fe(III)-oxo species directly from the activation of O2 that was subsequently oxidized to form a monomeric Fe(IV)-oxo species with an S = 2 spin state, similar to those species proposed as key intermediates in non-heme monooxygenases. We also demonstrated that a single Mn(III)-oxo center that was prepared from water could be converted to a high-spin Mn(V)-oxo species via stepwise oxidation, a process that mimics the oxidative charging of the oxygen-evolving complex (OEC) of photosystem II. Current mechanisms for photosynthetic O-O bond formation invoke a Mn(IV)-oxyl species rather than the isoelectronic Mn(V)-oxo system as the key oxidant based on computational studies. However, there is no experimental information to support the existence of a Mn-oxyl radical. We therefore probed the amount of spin density on the oxido ligand of our complexes using EPR spectroscopy in conjunction with oxygen-17 labeling. Our findings showed that there is a significant amount of spin on the oxido ligand, yet the M-oxo bonds are best described as highly covalent and there is no indication that an oxyl radical is formed. These results offer the intriguing possibility that high-spin M-oxo complexes are involved in O-O bond formation in biology. Ligand redesign to incorporate H-bond accepting units (sulfonamido groups) simultaneously provided a metal ion binding pocket, adjacent H-bond acceptors, and an auxiliary binding site for a second metal ion. These properties allowed us to isolate a series of heterobimetallic complexes of Fe(III) and Mn(III) in which a group II metal ion was coordinated within the secondary coordination sphere. Examination of the influence of the second metal ion on the electron transfer properties of the primary metal center revealed unexpected similarities between Ca(II) and Sr(II) ions, a result with relevance to the OEC. In addition, the presence of a second metal ion was found to prevent intramolecular oxidation of the ligand with an O atom transfer reagent. PMID:26181849

  9. A robust microporous metal-organic framework as a highly selective and sensitive, instantaneous and colorimetric sensor for Eu³? ions.

    PubMed

    Gao, Yanfei; Zhang, Xueqiong; Sun, Wei; Liu, Zhiliang

    2015-01-28

    An extremely thermostable magnesium metal-organic framework (Mg-MOF) is reported for use as a highly selective and sensitive, instantaneous and colorimetric sensor for Eu(3+) ions. There has been extensive interest in the recognition and sensing of ions because of their important roles in biological and environmental systems. However, only a few of these systems have been explored for specific rare earth ion detection. A robust microporous Mg-MOF for the recognition and sensing of Eu(3+) ions with high selectivity at low concentrations in aqueous solutions has been synthesized. This stable metal-organic framework (MOF) contains nanoscale holes and non-coordinating nitrogen atoms inside the walls of the holes, which makes it a potential host for foreign metal ions. Based on the energy level matching and efficient energy transfer between the host and the guest, the Mg-MOF sensor is both highly selective and sensitive as well as instantaneous; thus, it is a promising approach for the development of luminescent probing materials with unprecedented applications and its use as an Eu(3+) ion sensor. PMID:25478996

  10. Optical metal-organic framework sensor for selective discrimination of some toxic metal ions in water.

    PubMed

    Shahat, Ahmed; Hassan, Hassan M A; Azzazy, Hassan M E

    2013-09-01

    This paper reports the development of a facile and effective approach, based on the use of Zr-based metal-organic frameworks (UiO-66) sensor with micropores geometry, shape and particle morphology for the visual detection and removal of ultra-traces of some toxic metal ions such as Bi(III), Zn(II), Pb(II), Hg(II) and Cd(II). UiO-66 was used as selective carriers for accommodating hydrophobic chromophore probes such as dithizone (DZ) without coupling agent for sensitive and selective discrimination of trace level of toxic analytes. The developed UiO-66 sensor was utilized for the detection of ultra-traces of some toxic metal ions with the naked eye. The new sensor displays high sensitivity and selectivity of a wide range of detectable metals analytes up to 10(-10) mol dm(-3) in solution, in a rapid analyte uptake response (seconds). The developed sensor is stable, cost effective, easy to prepare, and would be useful for rapid detection and removal of ultra-traces of toxic metal ions in water samples. PMID:23953211

  11. Designated Drivers: The Differing Roles of Divalent Metal Ions in Surfactant Adsorption at the Oil-Water Interface

    E-print Network

    Richmond, Geraldine L.

    decanoate at the carbon tetrachloride-water interface. For all ions studied, the ions drive the adsorption been extensive studies modeling humic acid to understand the binding activities of metal ions.1-9 Metal In addition, metal ions, particularly transition metals, are required for catalysis in roughly one

  12. Metal Ion Binding and Enzymatic Mechanism of Methanococcus jannaschii RNase Bing Lai, Ying Li, Aoneng Cao, and Luhua Lai*

    E-print Network

    Luhua, Lai

    Metal Ion Binding and Enzymatic Mechanism of Methanococcus jannaschii RNase HII Bing Lai, Ying Li the RNA moiety in DNA:RNA hybrid in a divalent metal ion dependent manner. It is essential to understand the role of metal ion in enzymatic mechanism. One of the key points in this study is how many metal ions

  13. Sputtering of metals at ion-electron irradiation

    NASA Astrophysics Data System (ADS)

    Martynenko, Yu. V.; Korshunov, S. N.; Skorlupkin, I. D.

    2014-02-01

    It has been found that, in contrast to the commonly accepted opinion, simultaneous irradiation by 15-keV Ar+ ions and 2.5-keV electrons at temperatures above 0.5 T m ( T m is the melting temperature) induces much larger sputtering of metallic copper, nickel, and steel than irradiation only by Ar+ ions. The effect increases with the temperature. At T = 0.7 T m, the sputtering coefficients in the case of ion-electron irradiation are more than twice as large as the sputtering coefficients in the case of irradiation by Ar+ ions. The experiments on the sublimation of copper show that the sublimation rate in the case of the heating of a sample by an electron beam is higher than that in the case of heating in an electric vacuum oven. The revealed effects are explained by the electron-induced excitation of adatoms (atoms stuck over the surface, which appear owing to ion bombardment). Excited adatoms have a smaller binding energy with the surface and are sputtered more easily.

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

    PubMed

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

    2014-06-10

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

  15. Yttrium and rare earth stabilized fast reactor metal fuel

    DOEpatents

    Guon, Jerold (Woodland Hills, CA); Grantham, LeRoy F. (Calabasas, CA); Specht, Eugene R. (Simi Valley, CA)

    1992-01-01

    To increase the operating temperature of a reactor, the melting point and mechanical properties of the fuel must be increased. For an actinide-rich fuel, yttrium, lanthanum and/or rare earth elements can be added, as stabilizers, to uranium and plutonium and/or a mixture of other actinides to raise the melting point of the fuel and improve its mechanical properties. Since only about 1% of the actinide fuel may be yttrium, lanthanum, or a rare earth element, the neutron penalty is low, the reactor core size can be reduced, the fuel can be burned efficiently, reprocessing requirements are reduced, and the nuclear waste disposal volumes reduced. A further advantage occurs when yttrium, lanthanum, and/or other rare earth elements are exposed to radiation in a reactor, they produce only short half life radioisotopes, which reduce nuclear waste disposal problems through much shorter assured-isolation requirements.

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

    PubMed Central

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

    2014-01-01

    Background The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1–2 and 2–5 years. At 2–5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < –1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation Most cups and stems were well-fixed at 1–5 years. However, at 2–5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the fixation of hip components in large-head MoM articulations at medium-term follow-up. PMID:24847790

  17. Observations of nonadiabatic acceleration of ions in Earth's magnetotail

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Paterson, W. R.; Kivelson, M. G.

    1994-01-01

    We present observations of the three-dimensional velocity distributions of protons in the energy range 20 eV to 52 keV at locations within and near the current sheet of Earth's magnetotail at geocentric radial distances 35 to 87 R(sub E). These measurements were acquired on December 8, 1990, with a set of electrostatic analyzers on board the Galileo spacecraft during its approach to Earth in order to obtain one of its gravitational assists to Jupiter. It is found that the velocity distributions are inadequately described as quasi-Maxwellian distributions such as those found in the central plasma sheet at positions nearer to Earth. Instead the proton velocity distributions can be categorized into two major types. The first type is the 'lima bean' shaped distribution with high-speed bulk flows and high temperatures that are similar to those found nearer to Earth in the plasma sheet boundary layer. The second type consists of colder protons with considerably lesser bulk flow speeds. Examples of velocity distributions are given for the plasma mantle, a region near the magnetic neutral line, positions earthward and tailward of the neutral line, and the plasma sheet boundary layer. At positions near the neutral line, only complex velocity distributions consisting of the colder protons are found, whereas both of the above types of distributions are found in and near the current sheet at earthward and tailward locations. Bulk flows are directed generally earthward and tailward at positions earthward and tailward of the neutral line, respectively. Only the high-speed, hot distribution is present in the plasma sheet boundary layer. The observations are interpreted in terms of the nonadiabatic acceleration of protons that flow into the current sheet from the plasma mantle. For this interpretation the hot, 'lima bean' shaped distributions are associated with meandering, or Speiser, orbits in the current sheet. It is suggested that the colder, lower-speed proton velocity distributions are the result of fractional or few gyromotions before ejection out of the current sheet, but this speculation must be further investigated with appropriate kinetic simulation of trajectories.

  18. Performance and Comparison of Lithium-Ion Batteries Under Low-Earth-Orbit Mission Profiles

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Smart, Marshall C.; Bugga, Ratnakumar V.; Manzo, Michelle A.; Miller, Thomas B.; Gitzendanner, Rob

    2007-01-01

    The performance of two 28 V, 25 Ah lithium-ion batteries is being evaluated under low-Earth-orbit mission profiles for satellite and orbiter applications. The batteries are undergoing life testing and have achieved over 12,000 cycles to 40 percent depth-of-discharge.

  19. Investigations of hyperfine and isotope structures in optical spectra of crystals with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Popova, M. N.

    2015-10-01

    This is a review of works on hyperfine and isotope structures in the spectra of rare-earth ions in crystals that have been performed at the Laboratory of Fourier Spectroscopy of the Institute for Spectroscopy, Russian Academy of Sciences. The applicability of these studies to the development of optical quantum memory is discussed.

  20. Theory of Auger neutralization and deexcitation of slow ions at metal surfaces M. A. Cazalilla

    E-print Network

    Muiño, Ricardo Díez

    Theory of Auger neutralization and deexcitation of slow ions at metal surfaces M. A. Cazalilla electrons to the Auger neutralization rate of a slow ion at a metal surface has been calculated. We have considered the scattering of He on Al and studied the effect of the ion potential on the neutralization rate

  1. Pulsed ion beam treatment of metals for improved surface properties

    SciTech Connect

    Renk, T.J.; Buchheit, R.; Sorensen, R.; Thompson, M.O.; Grabowski, K.S.

    1996-12-31

    This work builds on previously reported studies using an intense pulsed ion beam to achieve a rapid melt and resolidification (RMR) of a surface metallic layer. Alloys and bi-metal combinations were treated on the RHEPP-1 facility at Sandia National Laboratories sample location, < 10 J/cm{sup 2}. Numerical modeling of thermal histories neglecting ablation have yielded predictions consistent with diagnostic measurements of treated samples. The measurements included scanning electron microscopy (SEM), Rutherford Backscattering Spectrometry (RBS), X-Ray Diffraction (XRD), and electrochemical corrosion tests. Treatment of Al-, Fe-, and Ti-based alloys with multiple beam shots indicates that the extent and nature of beam-induced modification depends on the particular alloy, and on the total number of RMR cycles. Microhardness measurements of a treated and sectioned SS-304 sample show enhancements over bulk values of as much as 50%, and extending over 100 {micro}m below the surface. In treatment of bi-metal combinations (Ion Beam Mixing), the authors have investigated overcoats on Al-, Fe, and Ti-based alloys, where the overcoat layer is applied to the substrate by conventional means such as sputter deposition. In the case of Al, it is well known that certain transition metals (Ti, Cr, Zr, Nb, Hf) can improve corrosion resistance, but are almost insoluble in Al under equilibrium conditions. They have treated samples overcoated with all the metals listed, in thickness ranging from 300 {angstrom} to 2 {micro}m RBS measurements how the overcoat to have mixed into the substrate in peak amounts ranging from 2 at% to 8% to 30%.

  2. Temperature Dependence On The Emission Characteristics Of A AuGe Liquid Metal Alloy Ion Source

    SciTech Connect

    Ganetsos, Theodore; Laskaris, Nikos; Kotsos, Bill; Bischoff, Lothar; Pilz, Wolfgang; Akhmadaliev, Chavkat

    2007-04-23

    Focused ion beam systems employing liquid metal ion sources have become of increasing importance in the microelectronics industry. Maskless ion implantation as a modern patterning technique is one of the most attractive application of Focused Ion Beams. In spite of the fact that a great deal of research has been carried out on liquid metal ion sources, surprisingly few results exist on the temperature dependence of their emission characteristics. In this article we study a AuGe liquid metal alloy ion source. The unusual results are explained in terms of the abnormal behavior of the surface tension of the alloy with temperature.

  3. Mutation of outer-shell residues modulates metal ion co-ordination strength in a metalloenzyme.

    PubMed

    Foo, Jee-Loon; Jackson, Colin J; Carr, Paul D; Kim, Hye-Kyung; Schenk, Gerhard; Gahan, Lawrence R; Ollis, David L

    2010-07-15

    The metal ion co-ordination sites of many metalloproteins have been characterized by a variety of spectroscopic techniques and small-molecule model systems, revealing many important insights into the structural determinants of metal ion co-ordination. However, our understanding of this fundamentally and practically important phenomenon remains frustratingly simplistic; in many proteins it is essentially impossible to predict metal ion specificity and the effects of remote 'outer-shell' residues on metal ion co-ordination strength are also poorly defined. This is exemplified by our inability to explain why metalloenzymes with identical metal ion co-ordination spheres, such as the closely related orthologues of bacterial PTE (phosphotriesterase) from Agrobacterium radiobacter and Pseudomonas diminuta, display different metal ion specificity and co-ordination strength. In the present study, we present a series of PTE variants that all possess identical metal ion co-ordination spheres, yet display large differences in their metal ion co-ordination strength. Using measurement of the rates of metal ion dissociation from the active site alongside analysis of structural data obtained through X-ray crystallography, we show that 'outer-shell' residues provide essential support for the metal ion ligands, in effect buttressing them in their optimal orientation. Remote mutations appear to modulate metal ion interactions by increasing or decreasing the stabilizing effects of these networks. The present study therefore provides a description of how the greater protein fold can be modified to 'tune' the strength of metal ion co-ordination and metal ion specificity, as well as reinforcing the concept of proteins as ensembles of conformational states with unique structures and biochemical properties. PMID:20459397

  4. Liquid metal batteries : ambipolar electrolysis and alkaline earth electroalloying cells

    E-print Network

    Bradwell, David (David Johnathon)

    2011-01-01

    Three novel forms of liquid metal batteries were conceived, studied, and operated, and their suitability for grid-scale energy storage applications was evaluated. A ZnlITe ambipolar electrolysis cell comprising ZnTe dissolved ...

  5. How do coinage metal ions bind to benzene?

    NASA Astrophysics Data System (ADS)

    Dargel, Thomas K.

    1999-02-01

    The interaction of the metal ions Cu+, Ag+, and Au+ with a benzene molecule has been investigated employing various quantum chemical strategies such as density functionals, Hartree-Fock, second-order perturbation theory and coupled cluster techniques. The three coinage metal cations show interesting differences in their preferred site of complexation with the pisystem of benzene. Cu prefers a highly symmetric eta6 arrangement. In the Ag+-C6H6 complex the metal ion can change its position above the whole pi plane of benzene virtually barrier free. For Au the calculations predict as favoured site of complexation a position above the carbon backbone, i.e., at the periphery and not in the centre of the benzene ring. Unlike copper or silver, this latter site of complexation is significantly less stable in the case of gold. At our most sophisticated level of theory, the computationally predicted binding energies agree well with the experimental numbers for the copper and silver complexes. For the gold complex only an estimate is available experimentally and the calculated number probably provides the most accurate result for this property so far. 6 6

  6. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    SciTech Connect

    Lu, Yi

    2003-06-01

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

  7. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    SciTech Connect

    Lu, Yi

    2002-06-01

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

  8. Metal Ions: Driving the Orderly Assembly of Polyelectrolytes at a Hydrophobic Surface

    E-print Network

    Richmond, Geraldine L.

    Metal Ions: Driving the Orderly Assembly of Polyelectrolytes at a Hydrophobic Surface Daniel K occurring polyelectrolytes are highly tunable and depend strongly on the binding of metal ions commonly found in environmental and biological systems. While the metal complexation behaviors of many

  9. Observation of Photon Echoes From Evanescently Coupled Rare-Earth Ions in a Planar Waveguide

    NASA Astrophysics Data System (ADS)

    Marzban, Sara; Bartholomew, John G.; Madden, Stephen; Vu, Khu; Sellars, Matthew J.

    2015-07-01

    We report the measurement of the inhomogeneous linewidth, homogeneous linewidth, and spin-state lifetime of Pr3 + ions in a novel waveguide architecture. The TeO2 slab waveguide deposited on a bulk Pr3 +?Y2SiO5 crystal allows the 3H4?1D2 transition of Pr3 + ions to be probed by the optical evanescent field that extends into the substrate. The 2-GHz inhomogeneous linewidth, the optical coherence time of 70 ±5 ? s , and the spin-state lifetime of 9.8 ±0.3 s indicate that the properties of ions interacting with the waveguide mode are consistent with those of bulk ions. This result establishes the foundation for large, integrated, and high performance rare-earth-ion quantum systems based on a waveguide platform.

  10. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure.

    PubMed

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. PMID:25984984

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

    SciTech Connect

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

    1999-06-13

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

  12. Large-scale transport of metallic ions and the occurrence of thin ion layers in the polar ionosphere

    NASA Astrophysics Data System (ADS)

    Bedey, D. F.; Watkins, B. J.

    1997-05-01

    A necessary condition for the formation of thin metallic ion layers in the high-latitude ionosphere, when strong convective electric fields are present, is that these fields have a magnetically westward component. However, observations have shown that proper field direction does not guarantee the occurrence of a layer. A sufficient abundance of metallic ions is also required. We assert that the abundance of metallic ions (and hence occurrence of thin layers) is strongly influenced by large-scale ion transport, which at high latitudes is determined by the spatial and temporal structure of the large-scale convective electric field. A simple model is presented which indicates that on the dayside, ions should be lifted from the nominal background metallic layer below 100 km into the lower F region, where they flow horizontally in a narrow vertical stream (~50km) toward the nightside. Upon entering the nightside this stream of metallic ions precipitates within a limited band of geomagnetic latitudes, leading to spatially selective enhancements of ion abundance within the E region. Given an appropriately directed convective electric field, the rate of occurrence of detectable thin ion layers should be greater at those locations where precipitation has occurred and, conversely, should be less where precipitation has not occurred. We suggest that this process controls the abundance of metallic ions and therefore explains the fact that layers are sometimes absent in observations, despite the presence of westwardly directed electric fields.

  13. Inner-shell photodetachment of transition metal negative ions

    NASA Astrophysics Data System (ADS)

    Dumitriu, Ileana

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

  14. Coupling of a locally implanted rare-earth ion ensemble to a superconducting micro-resonator

    NASA Astrophysics Data System (ADS)

    Wisby, I.; de Graaf, S. E.; Gwilliam, R.; Adamyan, A.; Kubatkin, S. E.; Meeson, P. J.; Tzalenchuk, A. Ya.; Lindström, T.

    2014-09-01

    We demonstrate the coupling of rare-earth ions locally implanted in a substrate (Gd3+ in Al2O3) to a superconducting NbN lumped-element micro-resonator. The hybrid device is fabricated by a controlled ion implantation of rare-earth ions in well-defined micron-sized areas, aligned to lithographically defined micro-resonators. The technique does not degrade the internal quality factor of the resonators which remain above 105. Using microwave absorption spectroscopy, we observe electron-spin resonances in good agreement with numerical modelling and extract corresponding coupling rates of the order of 1 MHz and spin linewidths of 50-65 MHz.

  15. Coupling of a locally implanted rare-earth ion ensemble to a superconducting micro-resonator

    E-print Network

    I. Wisby; S. E. de Graaf; R. Gwilliam; A. Adamyan; S. Kubatkin; P. J. Meeson; A. Ya. Tzalenchuk; T. Lindström

    2014-09-10

    We demonstrate the coupling of rare-earth ions locally implanted in a substrate (Gd$^{3+}$ in Al$_{2}$O$_{3}$) to a superconducting NbN lumped-element micro-resonator. The hybrid device is fabricated by a controlled ion implantation of rare-earth ions in well-defined micron-sized areas, aligned to lithographically defined micro-resonators. The technique does not degrade the internal quality factor of the resonators which remain above $10^{5}$. Using microwave absorption spectroscopy we observe electron-spin resonances in good agreement with numerical modelling and extract corresponding coupling rates of the order of $1$ MHz and spin linewidths of $50 - 65$ MHz.

  16. Coupling of a locally implanted rare-earth ion ensemble to a superconducting micro-resonator

    SciTech Connect

    Wisby, I. Tzalenchuk, A. Ya.; Graaf, S. E. de; Adamyan, A.; Kubatkin, S. E.; Gwilliam, R.; Meeson, P. J.; Lindström, T.

    2014-09-08

    We demonstrate the coupling of rare-earth ions locally implanted in a substrate (Gd{sup 3+} in Al{sub 2}O{sub 3}) to a superconducting NbN lumped-element micro-resonator. The hybrid device is fabricated by a controlled ion implantation of rare-earth ions in well-defined micron-sized areas, aligned to lithographically defined micro-resonators. The technique does not degrade the internal quality factor of the resonators which remain above 10{sup 5}. Using microwave absorption spectroscopy, we observe electron-spin resonances in good agreement with numerical modelling and extract corresponding coupling rates of the order of 1?MHz and spin linewidths of 50–65?MHz.

  17. Interpreting Micrometeoroid Residues on Metallic Spacecraft Surfaces: Clues from Low Earth Orbit, the Laboratory and to Come from Stardust?

    NASA Astrophysics Data System (ADS)

    Kearsley, A. T.; Burchell, M. J.; Graham, G. A.; Cole, M. J.; Wallis, D.

    2005-03-01

    Micrometeoroid impacts leave residue. Laboratory light gas gun shots provide a good velocity analogue for impacts on metal components of Stardust, the residues may help to identify cometary residues on metallic spacecraft surfaces in low Earth orbit.

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

    SciTech Connect

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

    2013-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  20. New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

    SciTech Connect

    Su, Yali; Li, Liyu; Nenoff, Tina M.; Nyman, May; Navrotsky, Alexnadra; Xu, Hongwu

    2003-09-11

    We are evaluating new metal niobate and silicotitanate ion exchangers for Cs and Sr removal and their related condensed phases as potential ceramic waste forms. The goal of the program is to provide DOE alternative materials that can exceed the solvent extraction process for removing Cs and Sr from high level wastes and technical alternatives for disposal of silicotitanate and niobate based ion exchange materials. To date we have determined the structural property relationship and thermodynamic stability of new silicotitanate and niobate based ion exchangers and their thermally converted phases. Several new phases include Na2Nb2-xMIV xO6-x(OH)x {center_dot} H2O (MIV=Ti, Zr, x=0.04 {approx} 0.4, SOMS), NaTixNb1-xO3-0.5x, Na2-xMxNb1.6Ti0.4O5.8+yx (M=Sr, Y), CsTixAl1-xSi2O6+x/2 (0 x 1), and Cc- A2TiSi6O15 (A=K, Rb, Cs) have been synthesized and characterized and results will be presented. Additionally, chemical, thermal, radiation, and thermodynamic stabilities of the new ion exchange materials and their related perovskites as potential ceramic waste forms will also be presented at the meeting.

  1. Capture of highly charged ions in a rare-earth permanent-magnet Penning trap

    NASA Astrophysics Data System (ADS)

    Guise, Nicholas D.; Brewer, Samuel M.; Tan, Joseph N.

    2011-05-01

    Highly charged ions extracted from the NIST electron beam ion trap (EBIT) are captured and stored in a rare-earth Penning trap built around a cylindrical NdFeB permanent magnet. Ions of charge qe , emerging from the EBIT with typical energy 4 . 0 q keV, are slowed electrostatically while entering the Penning trap, then captured by pulsing closed the Penning trap front endcap voltage at the time of arrival. Stored ions are later detected by pulsing open the back endcap to dump to a microchannel plate. In this first prototype trap,species including Ne10+ and N7+ are confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Such experiments will use a more elaborate apparatus that incorporates a two-magnet Penning trap for improved B-field homogeneity, a field-emission electron gun for in-trap loading of low- Z ions, and optical access for spectroscopy experiments on trapped ions. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, and plasma diagnostics. S.M. Brewer and J.N. Tan, BAPS.2009.DAMOP.T1.107.

  2. Electrolyte materials containing highly dissociated metal ion salts

    DOEpatents

    Lee, Hung-Sui (East Setauket, NY); Geng, Lin (Coram, NY); Skotheim, Terje A. (Shoreham, NY)

    1996-07-23

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

  3. Electrolyte materials containing highly dissociated metal ion salts

    DOEpatents

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

    1996-07-23

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

  4. Influence of electrode geometry on liquid metal ion source performance

    SciTech Connect

    Swanson, L.W.; Li, J.Z.

    1988-07-01

    The surface electric field distribution along the axis of a wetted needle type liquid metal ion source has been determined by numerical methods and is shown to exhibit a secondary maximum at the intersection of the cylindrical and conical sections. It is shown that the volume flow rate of the liquid metal film along the cylindrical portion of the emitter is adequate to resupply the ionized portion at the needle apex. However, a pressure minimum in the liquid film, which decreases with increasing apex cone angle, occurs at the cone/cylinder intersection and the pressure gradient formed on the conical section of the emitter opposes flow to the apex region. It is shown that, by chemically roughening the conical section of the emitter, liquid film flow via microcapillary action occurs in such a way as to provide a low flow impedance to the apex.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  6. Extraction of trivalent rare-earth metal nitrates from concentrated aqueous salt solutions by triisoamyl phosphate

    SciTech Connect

    Pyartman, A.K.; Keskinov, V.A.; Puzikov, E.A.

    1995-01-01

    Equations are proposed for describing isotherms of extraction of trivalent rare earth metal nitrates from concentrated aqueous salt solutions by neat triisoamyl phosphate, which allow for variations in the activity coefficients of the components in organic phase over a wide range of its compositions. The phase extraction constants have been determined, with a hypothetical 1 mol kg{sup {minus}1} aqueous solution of a rare-earth metal nitrate and the state of pure components in organic phase with a mole fraction of 1.0 taken as standard.

  7. Noncovalent interaction or chemical bonding between alkaline earth cations and benzene? A quantum chemistry study using

    E-print Network

    Sussman, Joel L.

    Noncovalent interaction or chemical bonding between alkaline earth cations and benzene? A quantum earth metal ion±benzene complexes were performed using the density-functional theory (DFT) B3LYP and ab of the al- kaline earth metal ions to benzene may be attributed to s±p and p±p interactions, which are signi

  8. Investigation of the Structure of Yeast tRNAPhe by Nuclear Magnetic Resonance: Paramagnetic Rare Earth Ion Probes of Structure

    PubMed Central

    Jones, Claude R.; Kearns, David R.

    1974-01-01

    The binding of paramagnetic rare earth ions to yeast tRNAPhe shifts some resonances in the low-field nuclear magnetic resonance spectrum that have been assigned to ring nitrogen protons of specific Watson-Crick base pairs. The changes in the nuclear magnetic resonance spectrum as the tRNA is titrated with Eu3+ indicate that 4 (or 5) Eu3+ ions are tightly bound, that the metal binding is in the fast exchange limit, and that the binding to different sites in the molecule is sequential rather than cooperative. The first metal bound simultaneously shifts resonances associated with the dihydrouridine and the -C-C-A stem. This permits us to conclude that the folding of the tRNAPhe in solution brings the phosphate backbone of the -C-C-A and the dihydrouridine stems into close proximity. A model of the three-dimensional structure of tRNAPhe incorporating this new information appears to be compatible with the results obtained from x-ray diffraction. PMID:4610573

  9. Yttrium and rare earth stabilized fast reactor metal fuel

    SciTech Connect

    Guon, J.; Grantham, L.F.; Specht, E.R.

    1992-05-12

    This patent describes an improved metal alloy reactor fuel consisting essentially of uranium, plutonium, and at least one element from the group consisting of yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

  10. Effects of selected metal ions on photodegradation of organophosphorus pesticides sensitized by humic acids.

    PubMed

    Kamiya, M; Kameyama, K

    2001-10-01

    Selected metal ions having paramagnetic property were found to exert inhibition effects on aquatic photodegradation of organophosphorus pesticides sensitized by humic acids, according to the increasing order of Cr(III) < Co(II) < Mn(II) < Cu(II). Basic factors dominating the metal-ion effects were clarified on the basis of the fluorescence quenching as well as radical scavenging abilities of metal ions complexed with humic acids. PMID:11592411

  11. First-principles study of He point-defects in HCP rare-earth metals

    SciTech Connect

    Li, Yang; Chen, Ru; Peng, SM; Long, XG; Wu, Z.; Gao, Fei; Zu, Xiaotao

    2011-05-01

    He defect properties in Sc, Y, Gd, Tb, Dy, Ho, Er and Lu were studied using first-principles calculations based on density functional theory. The results indicate that the formation energy of an interstitial He atom is smaller than that of a substitutional He atom in all hcp rare-earth metals considered. Furthermore, the tetrahedral interstitial position is more favorable than an octahedral position for He defects. The results are compared with those from bcc and fcc metals.

  12. Interaction of calcium with the human divalent metal-ion transporter-1

    SciTech Connect

    Shawki, Ali; Mackenzie, Bryan

    2010-03-12

    Iron deficiency is the most prevalent micronutrient deficiency worldwide. Whereas dietary calcium is known to reduce the bioavailability of iron, the molecular basis of this interaction is not understood. We tested the hypothesis that divalent metal-ion transporter-1 (DMT1)-the principal or only mechanism by which nonheme iron is taken up at the intestinal brush border-is shared also by calcium. We expressed human DMT1 in RNA-injected Xenopus oocytes and examined its activity using radiotracer assays and the voltage clamp. DMT1 did not mediate {sup 45}Ca{sup 2+} uptake. Instead, we found that Ca{sup 2+} blocked the Fe{sup 2+}-evoked currents and inhibited {sup 55}Fe{sup 2+} uptake in a noncompetitive manner (K{sub i} {approx} 20 mM). The mechanism of inhibition was independent of voltage and did not involve intracellular Ca{sup 2+} signaling. The alkaline-earth metal ions Ba{sup 2+}, Sr{sup 2+}, and Mg{sup 2+} also inhibited DMT1-mediated iron-transport activity. We conclude that Ca{sup 2+} is a low-affinity noncompetitive inhibitor-but not a transported substrate-of DMT1, explaining in part the effect of high dietary calcium on iron bioavailability.

  13. Rare-earth metal ?-complexes of reduced arenes, alkenes, and alkynes: bonding, electronic structure, and comparison with actinides and other electropositive metals.

    PubMed

    Huang, Wenliang; Diaconescu, Paula L

    2015-09-21

    Rare-earth metal complexes of reduced ? ligands are reviewed with an emphasis on their electronic structure and bonding interactions. This perspective discusses reduced carbocyclic and acyclic ? ligands; in certain categories, when no example of a rare-earth metal complex is available, a closely related actinide analogue is discussed. In general, rare-earth metals have a lower tendency to form covalent interactions with ? ligands compared to actinides, mainly uranium. Despite predominant ionic interactions in rare-earth chemistry, covalent bonds can be formed with reduced carbocyclic ligands, especially multiply reduced arenes. PMID:26247323

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

    SciTech Connect

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

    2011-08-14

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

  15. Structure of the Alkali-metal-atom-Strontium molecular ions: towards photoassociation and formation of cold molecular ions

    E-print Network

    Mireille Aymar; Romain Guérout; Olivier Dulieu

    2011-02-24

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

  16. [Relationship of biosorption capacity of heavy metal ions by Saccharomyces cerevisiae and their ionic characteristics].

    PubMed

    Chen, Can; Wang, Jian-Long

    2007-08-01

    Utilizing similar methods and ideas of QSAR in metal toxicity assessment, we tried to establish the relationship between the ion characteristics of heavy metals and the biosorption capacity by waste biomass of Saccharomyces cerevisiae, obtained from a local brewery. The biosorption experiment was carried out and the maximum biosorption capacity (q(max)) was determined by the Langmuir isotherm model. The values of q(max) decreased in order on mole basis: Pb2+ > Ag+ > Cr3+ > Cu2+ > Zn2+ > Cd2+ > Co2+ > Sr2+ > Ni2+ > Cs+. The biomass prefer to bind class B ions (Pb2+ and Ag+), then borderline ions, and last hard ions (Sr2+ and Cs+) based on the HASB principle. Twenty two parameters of physiochemical characteristics of ions were selected to correlate q(max). Linear regression analysis showed that only one parameter, i.e., the covalent index X2(m)r was correlated well to q(max) for all metal ions tested. The greater the covalent index value of metal ion was, the greater was potential to form covalent bonds with biological ligands, and the larger was the metal ion biosorption. Classification of metal ions (for divalent ion or for soft-hard ion) improved the models. More properties such as polarizing power Z2/r or the first hydrolysis constant /lgK(OH)/ or ionization potential IP were statistically significant. X2(m)r seemed to be suitable to account for metal ions containing soft ions, whereas Z2/r, /lgK(OH)/ and IP suitable for only soft ions or metal ions without soft ions. PMID:17926402

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

    PubMed Central

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

    2013-01-01

    Objectives The aims of this piece of work were to: 1) record the background concentrations of blood chromium (Cr) and cobalt (Co) concentrations in a large group of subjects; 2) to compare blood/serum Cr and Co concentrations with retrieved metal-on-metal (MoM) hip resurfacings; 3) to examine the distribution of Co and Cr in the serum and whole blood of patients with MoM hip arthroplasties; and 4) to further understand the partitioning of metal ions between the serum and whole blood fractions. Methods A total of 3042 blood samples donated to the local transfusion centre were analysed to record Co and Cr concentrations. Also, 91 hip resurfacing devices from patients who had given pre-revision blood/serum samples for metal ion analysis underwent volumetric wear assessment using a coordinate measuring machine. Linear regression analysis was carried out and receiver operating characteristic curves were constructed to assess the reliability of metal ions to identify abnormally wearing implants. The relationship between serum and whole blood concentrations of Cr and Co in 1048 patients was analysed using Bland-Altman charts. This relationship was further investigated in an in vitro study during which human blood was spiked with trivalent and hexavalent Cr, the serum then separated and the fractions analysed. Results Only one patient in the transfusion group was found to have a blood Co > 2 µg/l. Blood/Serum Cr and Co concentrations were reliable indicators of abnormal wear. Blood Co appeared to be the most useful clinical test, with a concentration of 4.5 µg/l showing sensitivity and specificity for the detection of abnormal wear of 94% and 95%, respectively. Generated metal ions tended to fill the serum compartment preferentially in vivo and this was replicated in the in vitro study when blood was spiked with trivalent Cr and bivalent Co. Conclusions Blood/serum metal ion concentrations are reliable indicators of abnormal wear processes. Important differences exist however between elements and the blood fraction under study. Future guidelines must take these differences into account. PMID:23836464

  18. Amorphous Metallic Glass as New High Power and Energy Density Anodes For Lithium Ion Rechargeable Batteries

    E-print Network

    Meng, Shirley Y.

    We have investigated the use of aluminum based amorphous metallic glass as the anode in lithium ion rechargeable batteries. Amorphous metallic glasses have no long-range ordered microstructure; the atoms are less closely ...

  19. Computational study of the complexation of metal ion precursors in dendritic polymers 

    E-print Network

    Tarazona Vasquez, Francisco

    2009-05-15

    Metal ions are important for medical, environmental and catalytic applications. They are used as precursor molecules for the manufacture of metal nanocatalysts, which are promising materials for an array of biomedical, ...

  20. Ion velocity distributions in the vicinity of the current sheet in Earth's distant magnetotail

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Paterson, W. R.; Ackerson, K. L.; Kokubun, S.; Kivelson, M. G.; Yamamoto, T.; Fairfield, D. H.

    1994-01-01

    Observations of the three-dimensional velocity distributions of positive ions and electrons have been recently gained for the first time in Earth's distant magnetotail with the Galileo and Geotail spacecraft. For this brief discussion of these exciting results the focus is on the overall character of the ion velocity distributions during substorm activity. The ion velocity distributions within and near the magnetotail current sheet are not accurately described as convecting, isotropic Maxwellians. The observed velocity distributions are characterized by at least two robust types. The first type is similar to the 'lima bean'-shaped velocity distributions that are expected from the nonadiabatic acceleration of ions which execute Speiser-type trajectories in the current sheet. The second distribution is associated with the presence of cold ion beams that presumably also arise from the acceleration of plasma mantle ions in the electric and weak magnetic fields in the current sheet. The ion velocity distributions in a magnetic field structure that is similar to that for plasmoids are also examined. Again the velocity distributions are not Maxwellian but are indicative of nonadiabatic acceleration. An example of the pressure tensor within the plasmoid-like event is also presented because it is anticipated that the off-diagonal elements are important in a description of magnetotail dynamics. Thus our concept of magnetotail dynamics must advance from the present assumption of co-moving electron and ion Maxwellian distributions into reformulations in terms of global kinematical models and nonadiabatic particle motion.

  1. Bond nature of active metal ions in SiO2-based electrochemical metallization memory cells.

    PubMed

    Cho, Deok-Yong; Tappertzhofen, Stefan; Waser, Rainer; Valov, Ilia

    2013-03-01

    Electrochemical metallization cells are candidates for the next-generation non-volatile memory devices based on resistive switching. Despite the intensive studies in recent years a microscopic model of the processes in these nanoscale electrochemical systems is still missing and the physicochemical properties of the active metal ions have been rarely reported. We examined the bonding characteristics of Cu(z+) and Ag(+) ions in SiO(2)-based cells using soft X-ray absorption spectroscopy. Whereas the Ag/SiO(2) interfaces showed no chemical interaction of Ag ions, the Cu/SiO(2) showed clear signatures of partial oxidation into two ionic species of Cu(2+) and Cu(+). The analyses on the orbital hybridization strength evidently showed that the Cu(2+)-O(2-) bonds in SiO(2) are much weaker than the Cu(+)-O(2-) bonds, analogous to the case of bulk CuO and Cu(2)O. This suggests that the Cu(2+) ions should be more mobile and with a dominating role in the process of resistive switching. PMID:23354222

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

    SciTech Connect

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

    2014-09-28

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

  3. Nonthermal ions and associated magnetic field behavior at a quasi-parallel earth's bow shock

    NASA Technical Reports Server (NTRS)

    Wilkinson, W. P.; Pardaens, A. K.; Schwartz, S. J.; Burgess, D.; Luehr, H.; Kessel, R. L.; Dunlop, M.; Farrugia, C. J.

    1993-01-01

    Attention is given to ion and magnetic field measurements at the earth's bow shock from the AMPTE-UKS and -IRM spacecraft, which were examined in high time resolution during a 45-min interval when the field remained closely aligned with the model bow shock normal. Dense ion beams were detected almost exclusively in the midst of short-duration periods of turbulent magnetic field wave activity. Many examples of propagation at large elevation angles relative to the ecliptic plane, which is inconsistent with reflection in the standard model shock configuration, were discovered. The associated waves are elliptically polarized and are preferentially left-handed in the observer's frame of reference, but are less confined to the maximum variance plane than other previously studied foreshock waves. The association of the wave activity with the ion beams suggests that the former may be triggered by an ion-driven instability, and possible candidates are discussed.

  4. Estimation of Heavy Ion Densities From Linearly Polarized EMIC Waves At Earth

    SciTech Connect

    Kim, Eun-Hwa; Johnson, Jay R.; Lee, Dong-Hun

    2014-02-24

    Linearly polarized EMIC waves are expected to concentrate at the location where their wave frequency satisfies the ion-ion hybrid (IIH) resonance condition as the result of a mode conversion process. In this letter, we evaluate absorption coefficients at the IIH resonance in the Earth geosynchronous orbit for variable concentrations of helium and azimuthal and field-aligned wave numbers in dipole magnetic field. Although wave absorption occurs for a wide range of heavy ion concentration, it only occurs for a limited range of azimuthal and field-aligned wave numbers such that the IIH resonance frequency is close to, but not exactly the same as the crossover frequency. Our results suggest that, at L = 6.6, linearly polarized EMIC waves can be generated via mode conversion from the compressional waves near the crossover frequency. Consequently, the heavy ion concentration ratio can be estimated from observations of externally generated EMIC waves that have polarization.

  5. Nanoparticles reduce nickel allergy by capturing metal ions

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  6. Behaviour of zirconium, niobium, yttrium and the rare earth elements in the Thor Lake rare-metal

    E-print Network

    Behaviour of zirconium, niobium, yttrium and the rare earth elements in the Thor Lake rare-metal © Emma Rebecca Sheard, 2010 #12;i ABSTRACT The Thor Lake rare-metal (Zr, Nb, Y, REE, Ta, Be, Ga) deposit and the heavy rare earth elements in the world. Much of the potentially economic mineralization was concentrated

  7. Prostate cancer outcome and tissue levels of metal ions

    USGS Publications Warehouse

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

    2011-01-01

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

  8. Surface energetics of alkaline-earth metal oxides: Trends in stability and adsorption of small molecules

    NASA Astrophysics Data System (ADS)

    Bajdich, Michal; Nørskov, Jens K.; Vojvodic, Aleksandra

    2015-04-01

    We present a systematic theoretical investigation of the surface properties, stability, and reactivity of rocksalt type alkaline-earth metal oxides including MgO, CaO, SrO, and BaO. The accuracy of commonly used exchange-correlation density functionals (LDA, PBE, RPBE, PBEsol, BEEF-vdW, and hybrid HSE) and random-phase approximation (RPA) is evaluated and compared to existing experimental values. Calculated surface energies of the four most stable surface facets under vacuum conditions, the (100) surface, the metal and oxygen terminated octopolar (111), and the (110) surfaces, exhibit a monotonic increase in stability from MgO to BaO. On the MgO(100) surface, adsorption of CO, NO, and CH4 is characterized by physisorption while H2O chemisorbs, which is in agreement with experimental findings. We further use the on-top metal adsorption of CO and NO molecules to map out the surface energetics of each alkaline-earth metal oxide surface. The considered functionals all qualitatively predict similar adsorption energy trends. The ordering between the adsorption energies on different surface facets can be attributed to differences in the local geometrical surface structure and the electronic structure of the metal constituent of the alkaline-earth metal oxide. The striking observation that CO adsorption strength is weaker than NO adsorption on the (100) terraces as the period of the alkaline-earth metal in the oxide increases is analyzed in detail in terms of charge redistribution within the ? and ? channels of adsorbates. Finally, we also present oxygen adsorption and oxygen vacancy formation energies in these oxide systems.

  9. Effect of mechanical activation of rare-earth metal oxides on the viscosity of borate melts

    NASA Astrophysics Data System (ADS)

    Istomin, S. A.; Ivanov, A. V.; Ryabov, V. V.; Pastukhov, E. A.

    2012-02-01

    Effect of mechanical activation of yttrium-group rare-earth metal (REM) oxides on the viscosity of borate melts is studied. The concentration of Gd, Dy, Ho, and Lu oxides is found to affect the viscosity and solidification temperature of these melts.

  10. Experimentally determined Si isotope fractionation between silicate and Fe metal and implications for Earth's core formation

    NASA Astrophysics Data System (ADS)

    Shahar, Anat; Ziegler, Karen; Young, Edward D.; Ricolleau, Angele; Schauble, Edwin A.; Fei, Yingwei

    2009-10-01

    Stable isotope fractionation amongst phases comprising terrestrial planets and asteroids can be used to elucidate planet-forming processes. To date, the composition of the Earth's core remains largely unknown though cosmochemical and geophysical evidence indicates that elements lighter than iron and nickel must reside there. Silicon is often cited as a light element that could explain the seismic properties of the core. The amount of silicon in the core, if any, can be deduced from the difference in 30Si/ 28Si between meteorites and terrestrial rocks if the Si isotope fractionation between silicate and Fe-rich metal is known. Recent studies (e.g., [Georg R.B., Halliday A.N., Schauble E.A., Reynolds B.C., 2007. Silicon in the Earth's core. Nature 447 (31), 1102-1106.]; [Fitoussi, C., Bourdon, B., Kleine, T., Oberli, F., Reynolds, B. C., 2009. Si isotope systematics of meteorites and terrestrial peridotites: implications for Mg/Si fractionation in the solar nebula and for Si in the Earth's core. Earth Planet. Sci. Lett. 287, 77-85.]) showing (sometimes subtle) differences between 30Si/ 28Si in meteorites and terrestrial rocks suggest that Si missing from terrestrial rocks might be in the core. However, any conclusion based on Earth-meteorite comparisons depends on the veracity of the 30Si/ 28Si fractionation factor between silicates and metals at appropriate conditions. Here we present the first direct experimental evidence that silicon isotopes are not distributed uniformly between iron metal and rock when equilibrated at high temperatures. High-precision measurements of the silicon isotope ratios in iron-silicon alloy and silicate equilibrated at 1 GPa and 1800 °C show that Si in silicate has higher 30Si/ 28Si than Si in metal, by at least 2.0‰. These findings provide an experimental foundation for using isotope ratios of silicon as indicators of terrestrial planet formation processes. They imply that if Si isotope equilibrium existed during segregation of Earth's core-forming metal and silicate mantle, there should be an isotopic signature of Si in the core. Our experiments, combined with previous measurements of Si isotope ratios in meteorites and rocks representing the bulk silicate Earth, suggest that the formation of the Earth's core imparted a high 30Si/ 28Si signature to the bulk silicate Earth due to dissolution of ~ 6 wt% Si into the early core.

  11. Shifted homologous relationships between the transplutonium and early rare-earth metals

    SciTech Connect

    Ward, J.W.

    1984-01-01

    The physico-chemical properties of the late actinide metals americium through einsteinium are compared with their rare-earth counterparts. Localization of the 5f electrons beginning at americium signals the appearance of true rare-earth-like properties, but the homologous relationship is shifted to place americium below praseodymium, einsteinium then below europium. The comparison of crystal structure, phase transitions, vapor pressures and heats of vaporization reveals remarkable similarities, especially for Sm-Cf and Eu-Es, where the stability of the divalent metal becomes established and divalent chemistry then follows. There is of course a major perturbation at the half-filled shell at curium, and it may be argued that americium is the anomaly in the so-called second rare-earth series. However, the response of americium, berkelium and californium under pressure reveals the true perturbation to be a thermodynamic one, occurring at curium.

  12. Isotope fractionation in surface ionization ion source of alkaline-earth iodides

    SciTech Connect

    Suzuki, T.; Kanzaki, C.; Nomura, M.; Fujii, Y.

    2012-02-15

    The relationship between the isotope fractionation of alkaline-earth elements in the surface ionization ion source and the evaporation filament current, i.e., filament temperature, was studied. It was confirmed that the isotope fractionation depends on the evaporation filament temperature; the isotope fractionation in the case of higher temperature of filament becomes larger. The ionization and evaporation process in the surface ionization ion source was discussed, and it was concluded that the isotope fractionation is suppressed by setting at the lower temperature of evaporation filament because the dissociations are inhibited on the evaporation filament.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Mathews, J. D.

    1987-01-01

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

  16. Aluminum/alkaline earth metal composites and method for producing

    DOEpatents

    Russell, Alan M; Anderson, Iver E; Kim, Hyong J; Freichs, Andrew E

    2014-02-11

    A composite is provided having an electrically conducting Al matrix and elongated filaments comprising Ca and/or Sr and/or Ba disposed in the matrix and extending along a longitudinal axis of the composite. The filaments initially comprise Ca and/or Sr and/or Ba metal or allow and then may be reacted with the Al matrix to form a strengthening intermetallic compound comprising Al and Ca and/or Sr and/or Ba. The composite is useful as a long-distance, high voltage power transmission conductor.

  17. Ternary rare earth and actinoid transition metal carbides viewed as carbometalates

    SciTech Connect

    Dashjav, Enkhtsetseg; Kreiner, Guido; Schnelle, Walter; Wagner, Frank R.; Kniep, Ruediger Jeitschko, Wolfgang

    2007-02-15

    Ternary carbides A{sub x}T{sub y}C{sub z} (A=rare earth metals and actinoids; T=transition metals) with monoatomic species C{sup 4-} as structural entities are classified according to the criteria (i) metal to carbon ratio, (ii) coordination number of the transition metal by carbon atoms, and (iii) the dimensionality of the anionic network [T{sub y}C{sub z}]{sup n-}. Two groups are clearly distinguishable, depending on the metal to carbon ratio. Those where this ratio is equal to or smaller than 2 may be viewed as carbometalates, thus extending the sequence of complex anions from fluoro-, oxo-, and nitridometalates to carbometalates. The second group, metal-rich carbides with metal to carbon ratios equal to or larger than 4 is better viewed as typical intermetallics (''interstitial carbides''). The chemical bonding properties have been investigated by analyzing the Crystal Orbital Hamilton Population (COHP). The chemical bonding situation with respect to individual T-C bonds is similar in both classes. The main difference is the larger number of metal-metal bonds in the crystal structures of the metal-rich carbides.

  18. Metal Ion Morphology Observed by the ISAAC Instrument

    NASA Astrophysics Data System (ADS)

    Dymond, K. F.; Wolfram, K. D.; Budzien, S. A.; Nicholas, A. C.; McCoy, R. P.; Thomas, R. J.

    2001-05-01

    We present middle ultraviolet spectra between 1800 and 2900 Å showing the presence of several spectral lines due to emission by singly ionized iron and magnesium. The ionized iron lines near 2380 and 2600 Å lines are newly identified in the Earth's middle ultraviolet dayglow spectrum. We also present altitude versus latitude maps of the Fe+ and Mg+ emissions showing fountain effect upwelling near the geomagnetic equator. Ion upwelling is also observed near both poles. This upwelling is attributed to an of Ex B drift due to antisunward convection over the polar cap [Grebowsky et al., GRL, 5, 791-794, 1978; Grebowsky and Pharo, Planetary and Space Science, 33, 807-815, 1985; Kumar and Hanson, JGR, 85, 6,783-6,801, 1980], rather than Joule heating. Layers of ions, confined to narrow altitude ranges, are also observed. These layers extend continuously from +/-15° magnetic latitude to +/-60° latitude. Several parallel layers are observed; these layers start at approximately 100 km altitude and are separated by approximately 50 km. A subsequent talk will present model results showing good qualitative agreement between the low latitude portions of these maps and calculations made using the SAMI-2 [Huba et al., JGR, 105, 23035-23054, 2000] model, which includes the fountain effect.

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

    SciTech Connect

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

    1990-05-01

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

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

    SciTech Connect

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

    2005-10-05

    Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA three-dimensional structures available from the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements; in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure, and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering.

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

    DOEpatents

    Smith, Barbara F. (Los Alamos, NM); Robinson, Thomas W. (Los Alamos, NM)

    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.

  2. Cross-sensitive rare-earth metal sensors based on bidentate neutral organophosphorus compounds and chlorinated cobalt dicarbollide.

    PubMed

    Legin, A V; Kirsanov, D O; Babain, V A; Borovoy, A V; Herbst, R S

    2006-07-21

    A variety of new chemical sensors (ion selective electrodes) for determination of rare-earth (RE) and trivalent metal cations such as yttrium(III), lanthanum(III), praseodymium(III), neodymium(III) and europium(III) that are commonly present in aqueous radiological samples, e.g. in high-level liquid waste (HLW) and solutions from reprocessing spent nuclear fuel, have been developed and studied. The sensors are based on bidentate neutral organophosphorus compounds, such as methylene bridged diphosphine dioxides and carbamoylmethylphosphine oxides, which are efficient extractants, especially when used in conjunction with chlorinated cobalt dicarbollide, for recovery and concentration of the RE and actinide elements from acidic HLW derived from the nuclear fuel cycle. The sensors exhibit remarkable sensitivity to RE cations and indicate promise for HLW analysis. PMID:17723484

  3. Rare earth zirconium oxide buffer layers on metal substrates

    DOEpatents

    Williams, Robert K. (Knoxville, TN); Paranthaman, Mariappan (Knoxville, TN); Chirayil, Thomas G. (Knoxville, TN); Lee, Dominic F. (Knoxville, TN); Goyal, Amit (Knoxville, TN); Feenstra, Roeland (Knoxville, TN)

    2001-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0metal-organic decomposition. The laminate article can include a layer of YBCO over the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  4. Ion engine propelled Earth-Mars cycler with nuclear thermal propelled transfer vehicle, volume 2

    NASA Technical Reports Server (NTRS)

    Meyer, Rudolf X.; Baker, Myles; Melko, Joseph

    1994-01-01

    The goal of this project was to perform a preliminary design of a long term, reusable transportation system between earth and Mars which would be capable of providing both artificial gravity and shelter from solar flare radiation. The heart of this system was assumed to be a Cycler spacecraft propelled by an ion propulsion system. The crew transfer vehicle was designed to be propelled by a nuclear-thermal propulsion system. Several Mars transportation system architectures and their associated space vehicles were designed.

  5. Accumulation of alkaline earth metals by the green macroalga Bryopsis maxima.

    PubMed

    Takahashi, Shigekazu; Aizawa, Kyoko; Nakamura, Saki; Nakayama, Katsumi; Fujisaki, Shingo; Watanabe, Soichiro; Satoh, Hiroyuki

    2015-04-01

    Twenty-five days after the disaster at the Fukushima Daiichi nuclear power plant in 2011, we collected samples of the green macroalga Bryopsis maxima from the Pacific coast of Japan. Bryopsis maxima is a unicellular, multinuclear, siphonous green macroalga. Radiation analysis revealed that B. maxima emitted remarkably high gamma radiation of (131)I, (134)Cs, (137)Cs, and (140)Ba as fission products of (235)U. Interestingly, B. maxima contained naturally occurring radionuclides derived from (226)Ra and (228)Ra. Analysis of element content revealed that B. maxima accumulates many ocean elements, especially high quantities of the alkaline earth metals Sr (15.9 g per dry-kg) and Ba (3.79 g per dry-kg), whereas Ca content (12.5 g per dry-kg) was lower than that of Sr and only 61 % of the mean content of 70 Japanese seaweed species. Time-course analysis determined the rate of radioactive (85)Sr incorporation into thalli to be approximately 0.13 g Sr per dry-kg of thallus per day. Subcellular fractionation of B. maxima cells showed that most of the (85)Sr was localized in the soluble fraction, predominantly in the vacuole or cytosol. Given that (85)Sr radioactivity was permeable through a dialysis membrane, the (85)Sr was considered to be a form of inorganic ion and/or bound with a small molecule. Precipitation analysis with sodium sulfate showed that more than 70% of the Sr did not precipitate as SrSO4, indicating that a proportion of the Sr may bind with small molecules in B. maxima. PMID:25744028

  6. The t-matrix resistivity of liquid rare earth metals using pseudopotential

    NASA Astrophysics Data System (ADS)

    Bhatia, Kamaldeep G.; Bhatt, N. K.; Vyas, P. R.; Gohel, V. B.

    2015-06-01

    Present theoretical study of liquid metal resistivity of some trivalent (La,Ce,Gd) and divalent (Eu,Yb) rare earth metals using pseudopotential has been carried out employing Ziman's weak scattering and transition matrix (t-matrix) approaches. Our computed results of liquid metal resistivity using t-matrix approach are better than resistivity computed using Ziman's approach and are also in excellent agreement with experimental results and other theoretical findings. The present study confirms that for f-shell metals pseudopotential must be determined uniquely and t-matrix approach is more physical in comparison with Ziman's nearly free electron approach. The present pseudopotential accounts s-p-d hybridization properly. Such success encourages us to study remaining liquid state properties of these metals.

  7. Laser polarization and phase control of up-conversion fluorescence in rare-earth ions

    PubMed Central

    Yao, Yunhua; Zhang, Shian; Zhang, Hui; Ding, Jingxin; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong

    2014-01-01

    We theoretically and experimentally demonstrate the up-conversion fluorescence control via resonance-mediated two-photon absorption in rare-earth ions by varying both the laser polarization and phase. We show that both the laser polarization and phase can control the up-conversion fluorescence, and the up-conversion fluorescence intensity is decreased when the laser polarization changes from linear through elliptical to circular. We also show that the laser polarization will affect the control efficiency of the up-conversion fluorescence by varying the laser phase, and the circular polarization will reduce the control efficiency. Furthermore, we suggest that the control efficiency by varying the laser polarization and the effect of the laser polarization on the control efficiency by varying the laser phase can be artificially manipulated by controlling the laser spectral bandwidth. This optical control method opens a new opportunity to control the up-conversion fluorescence of rare-earth ions, which may have significant impact on the related applications of rare-earth ions. PMID:25465401

  8. Optical detection of a single rare-earth ion in a crystal.

    PubMed

    Kolesov, R; Xia, K; Reuter, R; Stöhr, R; Zappe, A; Meijer, J; Hemmer, P R; Wrachtrup, J

    2012-01-01

    Rare-earth-doped laser materials show strong prospects for quantum information storage and processing, as well as for biological imaging, due to their high-Q 4f?4f optical transitions. However, the inability to optically detect single rare-earth dopants has prevented these materials from reaching their full potential. Here we detect a single photostable Pr(3+) ion in yttrium aluminium garnet nanocrystals with high contrast photon antibunching by using optical upconversion of the excited state population of the 4f?4f optical transition into ultraviolet fluorescence. We also demonstrate on-demand creation of Pr(3+) ions in a bulk yttrium aluminium garnet crystal by patterned ion implantation. Finally, we show generation of local nanophotonic structures and cell death due to photochemical effects caused by upconverted ultraviolet fluorescence of praseodymium-doped yttrium aluminium garnet in the surrounding environment. Our study demonstrates versatile use of rare-earth atomic-size ultraviolet emitters for nanoengineering and biotechnological applications. PMID:22929786

  9. Grid-controlled metal ion sources for heavy ion fusion accelerators

    SciTech Connect

    Len, L.K.; Humphries, S. Jr.; Burkart, C.

    1986-01-01

    A variety of metal ions can be generated using vacuum arcs, but due to the nature of these arcs, the flux generated fluctuates in time. We have successfully employed electrostatically biased grids to control the plasma and to provide a well-behaved, space charge limited ion source. The grid prevents the plasma from entering the extraction gap before the main voltage pulse is applied. The extracted ion current is space charge limited, resulting in a constant output current even though the ion flux from the vacuum arc source varies considerably. There are several advantages over other conventional sources, for instance, thermionic sources are faced with heating problems especially for large area configurations, while gas-injection sources cause prefill problems because they take too long to reach equilibrium. We have performed extraction experiments with aluminium and indium arc sources. We have extracted 300 mA of pure Al/sup +/ at 30 kV for 10 ..mu..s. The normalized beam emittance has been measured to be 8 /times/ 10/sup /minus/7/ ..pi..-m-rad. 3 refs., 5 figs.

  10. Spindependent screening and Auger neutralization of He + ions in metals M. Alducin*

    E-print Network

    Muiño, Ricardo Díez

    Spin­dependent screening and Auger neutralization of He + ions in metals M. Alducin* Donostia electron densities of the medium. In a second step, the rates for Auger neutralization of a He + ion polarization of the emitted yield is measured when a He + projectile is neutralized in front of a metal surface

  11. Spin-dependent screening and Auger neutralization of He+ ions in metals

    E-print Network

    Muiño, Ricardo Díez

    Spin-dependent screening and Auger neutralization of He+ ions in metals M. Alducin* Donostia electron densities of the medium. In a second step, the rates for Auger neutralization of a He+ ion polarization of the emitted yield is measured when a He+ projectile is neutralized in front of a metal surface

  12. An unconventional origin of metal-ion rescue and inhibition in the Tetrahymena group I

    E-print Network

    Herschlag, Dan

    An unconventional origin of metal-ion rescue and inhibition in the Tetrahymena group I ribozyme metal ions. Herein we report that, in the Tetrahymena group I ribozyme reaction, the deleterious effect@cmgm+stanford+edu+ Abbreviations: E: the Tetrahymena L-21 ScaI ribozyme; G: gua- nosine; SA: generically, the oligonucleotide

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

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

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

  14. Solid Phase Luminescence of Several Rare Earth Ions on Ion-Exchange Films

    NASA Technical Reports Server (NTRS)

    Tanner, Stephen P.; Street, Kenneth W., Jr.

    1999-01-01

    The development and characterization of a novel ion-exchange film for solid-phase fluorometry and phosphorimetry is reported. This new cation-exchange material is suitable for spectroscopic applications in the ultraviolet and visible regions. It is advantageous because it, as a single entity, is easily recovered from solution and mounted in the spectrofluorometers. After preconcentration on the film, the luminescence intensity of lanthanide ions is several orders of magnitude greater than that of the corresponding solution, depending on the volume of solution and the amount of film. This procedure allows emission spectral measurements and determination of lanthanide ions at solution concentrations of < 5 (micro)g/L. The film may be stored for subsequent reuse or as a permanent record of the analysis. The major drawback to the use of the film is slow uptake of analyte due to diffusion limitations.

  15. Caging Metal Ions with Visible Light-Responsive Nanopolymersomes

    PubMed Central

    2015-01-01

    Polymersomes are bilayer vesicles that self-assemble from amphiphilic diblock copolymers, and provide an attractive system for the delivery of biological and nonbiological molecules due to their environmental compatibility, mechanical stability, synthetic tunability, large aqueous core, and hyperthick hydrophobic membrane. Herein, we report a nanoscale photoresponsive polymersome system featuring a meso-to-meso ethyne-bridged bis[(porphinato)zinc] (PZn2) fluorophore hydrophobic membrane solute and dextran in the aqueous core. Upon 488 nm irradiation in solution or in microinjected zebrafish embryos, the polymersomes underwent deformation, as monitored by a characteristic red-shifted PZn2 emission spectrum and confirmed by cryo-TEM. The versatility of this system was demonstrated through the encapsulation and photorelease of a fluorophore (FITC), as well as two different metal ions, Zn2+ and Ca2+. PMID:25518002

  16. Photoluminescence properties of the rare-earth ions in the TiO{sub 2} host nanofibers prepared via electrospinning

    SciTech Connect

    Wang Haiying; Wang Yu; Yang Yang; Li Xiang; Wang Ce

    2009-02-04

    Luminescent rare-earth (RE) ions doped TiO{sub 2} nanofibers have been prepared by electrospinning of a mixture solution of rare-earth acetylacetone (RE(C{sub 5}H{sub 7}O{sub 2}){sub 3})/titanium tetraisopropoxide (Ti (OiPr){sub 4})/poly(vinyl pyrrolidone) (PVP) (RE = Eu, Er, Ce, Pr), followed by calcination at high temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses demonstrated the morphology and the structure of the rare-earth doped TiO{sub 2} nanofibers. Exciting the nanofibers results in an energy transfer from surface states of TiO{sub 2} to that of the rare-earth ions and the photoluminescence is observed from the crystal field states of the rare-earth ions.

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

    SciTech Connect

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

    1996-08-01

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

  18. Earth magnetic field as analyzer of the cosmic ray ion charge in MONICA experiment

    NASA Astrophysics Data System (ADS)

    Bakaldin, A. V.; Voronov, S. A.

    2015-08-01

    The future onboard experiment MONICA (monitor of cosmic ray nuclei and ions) is aimed for studying the cosmic ray ion fluxes from H to Ni in the energy range 10-300 MeV/n in vicinity of Earth. It's main scientific objective is the measurement of ion ionization states, as well as elemental, isotope composition and energy spectra of Solar Energetic Particle (SEP) fluxes. The method of the ion ionization state measurement based on the usage of Earth magnetic field as a separator of particle charge will be utilized in this experiment. The present contribution is dedicated to investigate the possibilities and features of this method for the MONICA experiment. The real time dependences of inverse square of cut-off geomagnetic L-shell (LC-2) on magnetic rigidity (R) in rigidity range 640-2780 MV were studied experimentally during powerful SEP events December 13-15 2006. The possibility to simulate these dependences using the modern geomagnetic field models is analyzed as well.

  19. New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

    SciTech Connect

    Su, Yali; Nenoff, Tina M.; Navrotsky, Alexandra

    2002-06-01

    This project is a continuing EMSP project entitled ''New Silicotitanate Waste Forms: Development and Characterization.'' In our original study, the phase selection and chemical durability of silicotitanates (including commercially available IE-911) as a function of temperature (500 to 1000 C) was fully characterized by a combination of techniques including XRD, TEM, SEM, NMR, Raman spectroscopy, XAFS, XANES, and by thermodynamic studies. In addition, work on this program led to new discoveries not anticipated in the originally proposed research. Of particular importance was the discovery of a new ion exchange material that is selective for divalent cations under extreme conditions (e.g., acid solutions, competing cations), thus providing an alternative for removing Sr from mixed wastes. This material is converted easily by high-temperature, in situ heat treatment into a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of high-level waste (HLW) from reprocessed, spent nuclear fuel. This renewal project is based on the current needs in separation of cesium and strontium and the results obtained from our previous EMSP work. The purpose of this project is to deliver pertinent information that can be used to make rational decisions on selection of separation processes for cesium, strontium, and actinides. The objectives of this project are: (1) to establish the structure/property relationship between inorganic ion exchanger materials and their ability to selectively separate divalent cations under extreme operating conditions-This includes optimizing stoichiometry, synthesis, and pretreatment conditions for metal niobate and silicotitanate ion exchangers for maximum strontium and actinide-surrogate selectivity. (2) to fully characterize the phase relationships, structures, and thermodynamic and kinetic stabilities of these new phases and their related condensed phases (as potential ceramic waste forms) (3) to understand the chemical and thermodynamic stabilities of silicotitanate ion exchangers based on an in-depth comprehension of local bonding configurations and thermochemistry (4) to apply fundamental understanding to tailoring an ion exchanger that is ideally suited for a DOE needs and therefore has the potential for short-term deployment in the DOE complex

  20. New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

    SciTech Connect

    Su, Yali; Nenoff, Tina M.; Navrotsky, Alexandra

    2001-06-01

    This project is a continuing EMSP project entitled ''New Silicotitanate Waste Forms: Development and Characterization.'' In our original study, the phase selection and chemical durability of silicotitanates (including commercially available IE-911) as a function of temperature (500 to 1000 C) was fully characterized by a combination of techniques including XRD, TEM, SEM, NMR, Raman spectroscopy, XAFS, XANES, and by thermodynamic studies. In addition, work on this program led to new discoveries not anticipated in the originally proposed research. Of particular importance was the discovery of a new ion exchange material that is selective for divalent cations under extreme conditions (e.g., acid solutions, competing cations), thus providing an alternative for removing Sr from mixed wastes. This material is converted easily by high-temperature, in situ heat treatment into a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of high-level waste (HLW) from reprocessed, spent nuclear fuel. This renewal project is based on the current needs in separation of cesium and strontium and the results obtained from our previous EMSP work. The purpose of this project is to deliver pertinent information that can be used to make rational decisions on selection of separation processes for cesium, strontium, and actinides. The objectives of this project are: (1) to establish the structure/property relationship between inorganic ion exchanger materials and their ability to selectively separate divalent cations under extreme operating conditions-This includes optimizing stoichiometry, synthesis, and pretreatment conditions for metal niobate and silicotitanate ion exchangers for maximum strontium and actinide-surrogate selectivity. (2) to fully characterize the phase relationships, structures, and thermodynamic and kinetic stabilities of these new phases and their related condensed phases (as potential ceramic waste forms) (3) to understand the chemical and thermodynamic stabilities of silicotitanate ion exchangers based on an in-depth comprehension of local bonding configurations and thermochemistry (4) to apply fundamental understanding to tailoring an ion exchanger that is ideally suited for a DOE needs and therefore has the potential for short-term deployment in the DOE complex.

  1. Evidence for solar wind origin of energetic heavy ions in the earth's radiation belt

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Klecker, B.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.; Fan, C. Y.; Fisk, L. A.; Ogallagher, J. J.

    1978-01-01

    Analysis of data from our energetic ion composition experiment on ISEE-1 has revealed the presence of substantial fluxes of carbon, oxygen, and heavier ions above 400 keV/nucleon at L values between approximately 2.5 and 4 earth radii. The measured C/O ratio varies systematically from 1.3 at 450 keV/nucleon to 4.1 at 1.3 MeV/nucleon, and no iron is observed above 200 keV/nucleon. These results provide strong evidence for a solar wind origin for energetic ions in the outer radiation belt. The absence of iron and the increase of the carbon-to-oxygen ratio with energy suggest that the condition for the validity of the first adiabatic invariant may have a strong influence on the trapping of these particles.

  2. Energization of solar wind ions by reflection from the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Paschmann, G.; Sckopke, N.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.

    1980-01-01

    The existence of ion beams with energies a few times the solar wind energy and streaming outward from the earth's bow shock has been known for some time. To explain the observed ion energies, a simple reflection model has been proposed in which the particles gain energy by displacement parallel to the interplanetary electric field. In this model the energy gained in the reflection can be described as a function of the angles between the interplanetary magnetic field, the solar wind velocity, and the local shock normal. Ion beams under widely varying conditions have been observed in ISEE 1 and 2. For 18 cases, with beam energies ranging from approximately 1.4 to 30 times the solar wind energy, a comparison between the observed and the predicted beam energies has been made.

  3. Ion conics and counterstreaming electrons generated by lower hybrid waves in the earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Chang, Tom; Crew, Geoffrey B.; Retterrer, John M.; Jasperse, John R.

    1989-01-01

    The exotic phenomenon of energetic ion-conic and counterstreaming electron formation by lower hybrid waves along discrete auroral field lines in the earth magnetosphere is considered. Mean-particle calculations, plasma simulations, and analytical treatments of the acceleration processes are described. It is shown that, in the primary auroral electron-beam region, lower hybrid waves could be an efficient mechanism for the transverse heating of H (+) and O(+) ions of ionospheric origin, as well as for the field-aligned heating of the ambient electrons leading to coincident counterstreaming electron distributions. For O(+) ions to be energized by such a wave-particle interaction process, however, some sort of preheating mechanism is required.

  4. Kinetic theory for the ion humps at the foot of the Earth's bow shock

    SciTech Connect

    Jovanovic, D.; Krasnoselskikh, V. V.

    2009-10-15

    The nonlinear kinetic theory is presented for the ion acoustic perturbations at the foot of the Earth's quasiperpendicular bow shock, that is characterized by weakly magnetized electrons and unmagnetized ions. The streaming ions, due to the reflection of the solar wind ions from the shock, provide the free energy source for the linear instability of the acoustic wave. In the fully nonlinear regime, a coherent localized solution is found in the form of a stationary ion hump, which is traveling with the velocity close to the phase velocity of the linear mode. The structure is supported by the nonlinearities coming from the increased population of the resonant beam ions, trapped in the self-consistent potential. As their size in the direction perpendicular to the local magnetic field is somewhat smaller that the electron Larmor radius and much larger that the Debye length, their spatial properties are determined by the effects of the magnetic field on weakly magnetized electrons. These coherent structures provide a theoretical explanation for the bipolar electric pulses, observed upstream of the shock by Polar and Cluster satellite missions.

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

    PubMed

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

    2014-09-01

    Herein, a small-molecule fluorescent sensor array for rapid identification of seven heavy metal ions was designed and synthesized, with its sensing mechanism mimicking that of a tongue. The photoinduced electron transfer and intramolecular charge transfer mechanism result in combinatorial interactions between sensor array and heavy metal ions, which lead to diversified fluorescence wavelength shifts and emission intensity changes. Upon principle component analysis (PCA), this result renders clear identification of each heavy metal ion on a 3D spatial dispersion graph. Further exploration provides a concentration-dependent pattern, allowing both qualitative and quantitative measurements of heavy metal ions. On the basis of this information, a "safe-zone" concept was proposed, which provides rapid exclusion of versatile hazardous species from clean water samples based on toxicity characteristic leaching procedure standards. This type of small-molecule fluorescent sensor array could open a new avenue for multiple heavy metal ion detection and simplified water quality analysis. PMID:25144824

  6. A lithium liquid metal ion source suitable for high voltage terminal applications

    SciTech Connect

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

    1989-01-01

    Liquid metal ion sources offer potential improvement in lateral resolution over conventionally used gaseous sources for MeV microprobe applications because of their intrinsic brightnesses. The use of a Li liquid metal ion source is particularly attractive because of the increased sensitivity of lithium for detecting hydrogen (hydrogen profiling) and for detecting near surface contaminants through high-resolution Rutherford backscattering spectrometry. However, the technical difficulty of occasional sparking between the needle and extraction electrode requires that the needle of the Li liquid metal ion source be rewetted before reignition can be effected; this problem makes Li liquid metal ion sources of the usual design risky for operation in the insulated high-voltage terminals of accelerators used in such applications. We have designed a reliable, long-lived, Li liquid-metal ion source which has provisions for overcoming this limitation. The design features and performance characteristics of the source are described in this report. 9 refs., 4 figs.

  7. A lithium liquid metal ion source suitable for high voltage terminal applications

    NASA Astrophysics Data System (ADS)

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

    1990-01-01

    Liquid metal ion sources offer potential improvement in lateral resolution over conventionally used gaseous sources for MeV microprobe applications because of their intrinsic brightnesses. The use of a Li liquid metal ion source is particularly attractive because of the increased sensitivity of lithium for detecting hydrogen (hydrogen profiling) and for detecting near-surface contaminants through high-resolution Rutherford backscattering spectrometry. However, the technical difficulty of occasional sparking between the needle and extraction electrode requires that the needle of the Li liquid metal ion source be rewetted before reignition can be effected; this problem makes Li liquid metal ion sources of the usual design risky for operation in the insulated high-voltage terminals of accelerators used in such applications. We have designed a reliable, long-lived, Li liquid-metal ion source which has provisions for overcoming this limitation. The design features and performance characteristics of the source are described in this article.

  8. Polymer hybrid thin films based on rare earth ion-functionalized MOF: photoluminescence tuning and sensing as a thermometer.

    PubMed

    Shen, Xiang; Yan, Bing

    2015-01-28

    A series of photofunctional polymer hybrid thin films based on rare earth ion functionalized metal organic frameworks (MOFs, 1 for zinc complexes bio-MOF-1 (Zn8(ad)4(BPDC)6O·2Me2NH2) and 2 for rare earth complexes RE(BPDC)(Ad) (BPDC = biphenyl-4,4'-dicarboxylic acid, Ad = adenine) have been prepared via polymerization reaction of ethyl methacrylate (EMA) and 4-vinylpyridine (VPD). The as-obtained hybrid films were characterized by X-ray diffraction, FT-IR, and SEM, especially for the luminescence performance and sensing ability. These hybrid polymer thin films are dense and transparent and display multi-colors, including blue, red and blue-green. Among them, Y0.9Tb0.0999Eu(0.0001)-2 fabricated hybrid thin film displays a white light output. More significantly and interestingly, the Tb0.999Eu(0.001)-2 fabricated hybrid thin film can be used as luminescent ratiometric thermometer based on the energy transfer from Tb(3+) to Eu(3+), whose color will change from blue-green to pink from 100 K to 320 K. PMID:25485621

  9. Investigation of the Transport of Solar Ions Through the Earth's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.; Evans, David (Technical Monitor)

    2000-01-01

    The objective of this study has been to infer, by statistical means, the most probable mode of entry of solar wind plasma into Earth's magnetotail, using a particular set of archived data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE-1) satellite, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) in the 1970's and 80's. Despite their considerable age, the Lockheed ISEE-1 data are still, at the time of this report, the only substantial ion composition data in the sub-keV to keV energy range available from the magnetotail beyond 9 R(sub E), because of various technical problems with ion mass spectrometers on later missions, and are therefore a unique source of information about the mixing of solar and terrestrial origin plasmas in the tail, within the ISEE-1 apogee of almost 23 R(sub E). The entire set of archived data used in this study, covering the 4.5 years of operation of the instrument and comprising not only tail measurements but also data from the inner magnetosphere as well as data from outside the magnetopause, is now available to the public via the WorldWideWeb at the address: http://cis.spasci.com/ISEE_ions The fundamental assumption of this and other studies of magnetosphere ion composition is that He++ and O+ ions are virtually certain "tags" of solar and terrestrial origins, respectively. This is an assumption with strong theoretical basis and it is corroborated by observational evidence, including the often substantial differences between the velocity distribution functions of those two species. The H+ ions can have a dual origin, in principle, but the close resemblance in the ISEE-1 data between the dynamics of H+ and He++ ions indicates a predominantly solar origin of the H+ ions in the tail, at least. By the same token, the usually minor He+ ions are probably almost entirely of terrestrial origin, because of their similarity to the O+ ions.

  10. Nitrogen ion implantation in metals - A comparison of Experimental Results and Computer Simulations

    NASA Astrophysics Data System (ADS)

    Sanghera, Harpreet; Sullivan, John

    2000-04-01

    The aim of this work is to investigate the effects of ion energy, current density and dose on low energy nitrogen ion implantation profiles in metal surfaces. For this purpose, metal (Al, Fe, Cu and Au) bulk samples, with a purity of 99.9energies of 2, 3, 4 and 5 keV with current densities of 1 mA/cm2 and 5 mA/cm2 for each ion energy. The ion fluences for these experiments range from 6xE16 and 3xE17 ions/cm2. The chemical composition and chemical structure of the implanted metals were investigated by XPS and Angle Resolved X-ray Photoelectron Spectroscopy (ARXPS). The concentration profiles of nitrogen ions implanted into metals were measured by X-ray Photoelectron Spectroscopy (XPS) and these were compared with the profiles created using computer simulation codes SUSPRE and SATVAL.

  11. Sunflower stalks as adsorbents for the removal of metal ions from wastewater

    SciTech Connect

    Sun, G.; Shi, W.

    1998-04-01

    Sunflower stalks as adsorbents for the removal of metal ions such as copper, cadmium, zinc, and chromium ions in aqueous solutions were studied with equilibrium isotherms and kinetic adsorptions. The maximum adsorptions of four heavy metals are 29.3 mg/g (Cu{sup 2+}), 30.73 mg/g (Zn{sup 2+}), 42.18 mg/g (Cd{sup 2+}), and 25.07 mg/g (Cr{sup 3+}), respectively. Particle sizes of sunflower stalks affected the adsorption of metal ions; the finer size of particles showed better adsorption to the ions. Temperature also plays an interesting role in the adsorption of different metal ions. Copper, zinc, and cadmium exhibited lower adsorption on sunflower stalks at higher temperature, while chromium showed the opposite phenomenon. The adsorption rates of copper, cadmium, and chromium are quite rapid. Within 60 min of operation about 60--80% of these ions were removed from the solutions.

  12. Metal-clad optical waveguide fluorescence device for the detection of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Margheri, Giancarlo; Giorgetti, Emilia; Marsili, Paolo; Zoppi, Angela; Lascialfari, Luisa; Cicchi, Stefano

    2014-07-01

    We developed Hg-sensing chips by decorating the external surface of metal-clad optical waveguides with a monolayer of Hg-sensitive fluorescent molecular probes. The emission properties of the original water-soluble form of the molecule were previously found to be selectively quenched in the presence of Hg ions. The fabricated samples were tested with optical waveguide fluorescence spectroscopy by putting them in contact with a 5-?M water solution of Hg ions and recording the emission spectra versus incubation time. The estimate of the limit of detection was 150 nM. A preliminary evaluation of the selectivity of the structure was also performed by using Cd as possible interfering analytes.

  13. Arrays of Metal Nanostructures Produced by Focussed Ion Beam

    NASA Astrophysics Data System (ADS)

    Luches, P.; di Bona, A.; Contri, S. F.; Gazzadi, G. C.; Vavassori, P.; Albertini, F.; Casoli, F.; Nasi, L.; Fabbrici, S.; Valeri, S.

    2007-12-01

    We present a study of the magnetic properties of arrays of nanostructures produced in a focussed ion beam-scanning electron microscope dual beam system. The single magnetic units have been isolated either by direct removal of parts of the metallic film or by local modification of the film magnetic properties. The final quality of the shape and the residual damage strictly depend on beam parameters (spot size and pixel dwell time) and on the swelling properties of the patterned materials. On square Fe(001) elements with a well-defined intrinsic (magnetocristalline) and shape- and size- induced (shape plus configurational) anisotropy we show that the overall magnetic anisotropy is not a mere superposition of the individual contributions. We also demonstrate that with ion irradiation doses below the milling threshold L10 FePt films with perpendicular magnetic anisotropy undergo a transition from the magnetically hard L10 phase to the magnetically soft A1 phase leading to an out-of-plane to in-plane spin reorientation. The magnetic properties of the planar arrays obtained by local modification of the film are compared to arrays of sculpted structures of the same material.

  14. Porous metal oxide microspheres from ion exchange resin

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    SciTech Connect

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

    2015-02-28

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

  16. Focused ion beam milling and scanning electron microscopy characterization of polymer+metal hybrids

    E-print Network

    North Texas, University of

    Focused ion beam milling and scanning electron microscopy characterization of polymer+metal hybrids dispersion on the surfaces of the microhybrids. Focus ion beam (FIB) milling was used to create a transversal cut in the material. SEM imaging was performed before, during and after ion milling to investigate

  17. Formation of metallic nanostructures on the surface of ion- exchange glass by focused electron beam

    NASA Astrophysics Data System (ADS)

    Komissarenko, F. E.; Zhukov, M. V.; Mukhin, I. S.; Golubok, A. O.; Sidorov, A. I.

    2015-11-01

    This paper presents a new method for formation of metallic nanostructures on the surface of ion-exchange glass. The method is based on the interaction of a focused electron beam with ions in ion-exchange glass. In experiments nanostructures with different shapes were obtained, depending on the electrons irradiation conditions.

  18. METAL INTERACTIONS AT SULFIDE MINERAL SURFACES: PART 3, METAL AFFINITIES IN SINGLE AND MULTIPLE ION ADSORPTION REACTIONS

    EPA Science Inventory

    Adsorption reactions of both single ions and multiple ion mixtures with sulfide minerals (chalcocite, galena, pyrite, and sphalerite) were investigated in the metal concentration range of 0.0001 to 0.00001 M. Chromium (III), iron (III), barium (II), cadmium (II), copper (II), nic...

  19. Role of surface oxygen-to-metal ratio on the wettability of rare-earth oxides Sami Khan, Gisele Azimi, Bilge Yildiz, and Kripa K. Varanasi

    E-print Network

    Yildiz, Bilge

    Role of surface oxygen-to-metal ratio on the wettability of rare-earth oxides Sami Khan, GiseleAs native oxides J. Appl. Phys. 110, 034319 (2011); 10.1063/1.3619797 Ternary rare-earth metal oxide high- k hydrophobic. The unique electronic structure of the rare-earth metal atom inhibits hydrogen bonding

  20. Earth

    NASA Technical Reports Server (NTRS)

    Carr, M. H.

    1984-01-01

    The following aspects of the planet Earth are discussed: plate tectonics, the interior of the planet, the formation of the Earth, and the evolution of the atmosphere and hydrosphere. The Earth's crust, mantle, and core are examined along with the bulk composition of the planet.

  1. Predicted pressure-induced spin and electronic transition in double perovskite R2CoMnO6 (R = rare-earth ion).

    PubMed

    Zhao, Hong Jian; Zhou, Haiyang; Chen, Xiang Ming; Bellaiche, L

    2015-06-10

    Specific first-principles calculations are performed to predict structural, magnetic and electronic properties of seven double perovskite R2CoMnO6 materials, with R being a rare-earth ion, under hydrostatic pressure. All these compounds are found to undergo a first-order transition from a high spin (HS) to low spin (LS) state at a critical pressure (whose value is dependent on the R ion). Such transition not only results in a significant volume collapse but also yields a dramatic change in electronic structure. More precisely, the HS-to-LS transition is accompanied by a transition from an insulator to a half-metallic state in the R2CoMnO6 compounds having the largest rare-earth ionic radius (i.e., Nd, Sm, Gd and Tb) while it induces a change from an insulator to a semiconductor having a narrow band gap for the smallest rare-earth ions (i.e., R = Dy, Ho and Er). Experiments are called for to confirm these predictions. PMID:25984752

  2. Predicted pressure-induced spin and electronic transition in double perovskite R2CoMnO6 (R = rare-earth ion)

    NASA Astrophysics Data System (ADS)

    Zhao, Hong Jian; Zhou, Haiyang; Chen, Xiang Ming; Bellaiche, L.

    2015-06-01

    Specific first-principles calculations are performed to predict structural, magnetic and electronic properties of seven double perovskite R2CoMnO6 materials, with R being a rare-earth ion, under hydrostatic pressure. All these compounds are found to undergo a first-order transition from a high spin (HS) to low spin (LS) state at a critical pressure (whose value is dependent on the R ion). Such transition not only results in a significant volume collapse but also yields a dramatic change in electronic structure. More precisely, the HS-to-LS transition is accompanied by a transition from an insulator to a half-metallic state in the R2CoMnO6 compounds having the largest rare-earth ionic radius (i.e., Nd, Sm, Gd and Tb) while it induces a change from an insulator to a semiconductor having a narrow band gap for the smallest rare-earth ions (i.e., R = Dy, Ho and Er). Experiments are called for to confirm these predictions.

  3. Transition metal and rare earth quad-doped photovoltaic phosphate glasses toward raising a-SiC:H solar cell performance

    NASA Astrophysics Data System (ADS)

    Song, P.; Zhang, C. M.; Zhu, P. F.

    2016-01-01

    Efficiency enhancement of a hydrogenated amorphous-silicon carbide (a-SiC:H) solar cell using downshifting and upconversion of photovoltaic (PV) glasses doped with transition metal (TM) ions and rare earth (RE) ions are investigated. P2O5-Li2O-Al2O3-Sb2O3-MnO-Yb2O3-Er2O3 glass doped with Sb3+-Mn2+-Yb3+-Er3+ ions is prepared and the PV glass is placed on an a-SiC:H solar cell. The performance of the cell in combination with the PV glass is simulated and measured, and the results show that the theoretical and experimental efficiencies are both enhanced compared to the bare one. The potential of TM-RE quad-doped glasses for improving the efficiency of a-SiC:H PV modules are explored.

  4. Metal ions and protein aggregation: the case fo Prion protein and -amyloids

    E-print Network

    Morante, Silvia

    Metal ions and protein aggregation: the case fo Prion protein and -amyloids Silvia Morante community, is the structural rôle played by metals in intra-molecular and inter-molecular interactions. Metals are essential elements for many of the fundamental activities of cells. Storing, metabolism

  5. Highly isoselective coordination polymerization of ortho-methoxystyrene with ?-diketiminato rare-earth-metal precursors.

    PubMed

    Liu, Dongtao; Yao, Changguang; Wang, Rong; Wang, Meiyan; Wang, Zichuan; Wu, Chunji; Lin, Fei; Li, Shihui; Wan, Xinhua; Cui, Dongmei

    2015-04-20

    Stereoselective coordination/insertion polymerization of the polar ortho-methoxystyrene has been achieved for the first time by using the cationic ?-diketiminato rare-earth-metal species. High activity and excellent isoselectivity (mmmm>99?%) were acheived. The unmasked Lewis-basic methoxy group does not poison the Lewis-acidic metal center, but instead activates the polymerization through ?-? chelation to the active species together with the vinyl group, thus lower the coordination and activation energies as compared with those of styrene derivatives lacking the methoxy group. PMID:25728133

  6. Thermal oxidation of the surface of binary aluminum alloys with rare-earth metals

    NASA Astrophysics Data System (ADS)

    Akashev, L. A.; Popov, N. A.; Kuznetsov, M. V.; Shevchenko, V. G.

    2015-05-01

    The kinetics of oxidation of the surface of Al alloys with 1-2.5 at % rare-earth metals (REMs) at 400-500°C in air was studied by ellipsometry and X-ray photoelectron spectroscopy (XPS). The addition (1-2.5 at % REM) of all rare-earth metals to aluminum was shown to increase the thickness of the oxide layer. The addition of surfactant and chemically active REMs (Yb, Sm, La, and Ce) increased the rate of oxidation of solid aluminum most effectively. The oxidation can be accelerated by the polymorphic transformations of the individual REM oxides in the film. The surface activity of Sm with respect to solid Al was confirmed by XRS.

  7. Previously hidden low-energy ions: a better map of near-Earth space and the terrestrial mass balance

    NASA Astrophysics Data System (ADS)

    André, Mats

    2015-12-01

    This is a review of the mass balance of planet Earth, intended also for scientists not usually working with space physics or geophysics. The discussion includes both outflow of ions and neutrals from the ionosphere and upper atmosphere, and the inflow of meteoroids and larger objects. The focus is on ions with energies less than tens of eV originating from the ionosphere. Positive low-energy ions are complicated to detect onboard sunlit spacecraft at higher altitudes, which often become positively charged to several tens of volts. We have invented a technique to observe low-energy ions based on the detection of the wake behind a charged spacecraft in a supersonic ion flow. We find that low-energy ions usually dominate the ion density and the outward flux in large volumes in the magnetosphere. The global outflow is of the order of 1026 ions s–1. This is a significant fraction of the total number outflow of particles from Earth, and changes plasma processes in near-Earth space. We compare order of magnitude estimates of the mass outflow and inflow for planet Earth and find that they are similar, at around 1 kg s?1 (30 000 ton yr?1). We briefly discuss atmospheric and ionospheric outflow from other planets and the connection to evolution of extraterrestrial life.

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

    PubMed Central

    2014-01-01

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

  9. GYROSURFING ACCELERATION OF IONS IN FRONT OF EARTH's QUASI-PARALLEL BOW SHOCK

    SciTech Connect

    Kis, Arpad; Lemperger, Istvan; Wesztergom, Viktor; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Dandouras, Iannis E-mail: Kis.Arpad@csfk.mta.hu

    2013-07-01

    It is well known that shocks in space plasmas can accelerate particles to high energies. However, many details of the shock acceleration mechanism are still unknown. A critical element of shock acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-parallel bow shock resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Cluster spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow shock and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-parallel bow shock, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.

  10. Gyrosurfing Acceleration of Ions in Front of Earth's Quasi-parallel Bow Shock

    NASA Astrophysics Data System (ADS)

    Kis, Arpad; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Khotyaintsev, Yuri V.; Dandouras, Iannis; Lemperger, Istvan; Wesztergom, Viktor

    2013-07-01

    It is well known that shocks in space plasmas can accelerate particles to high energies. However, many details of the shock acceleration mechanism are still unknown. A critical element of shock acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-parallel bow shock resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Cluster spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow shock and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-parallel bow shock, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.

  11. Metal-Mediated Peptide Ion Conformations in the Gas Phase John A. Taraszka, Jianwei Li, and David E. Clemmer*

    E-print Network

    Clemmer, David E.

    Metal-Mediated Peptide Ion Conformations in the Gas Phase John A. Taraszka, Jianwei Li, and David E, 1999; In Final Form: February 24, 2000 The influence of metal cations and source temperature-resolution ion mobility techniques. Cross sections for non-metalated [ICA-nH]n- (n ) 2-6) ions show a distinct

  12. Does a Single Metal Ion Bridge the A-9 and Scissile Phosphate Groups in the Catalytically Active

    E-print Network

    Scott, William

    ERRATUM Does a Single Metal Ion Bridge the A-9 and Scissile Phosphate Groups in the Catalytically±41 Figure 3 of the above paper shows the divalent metal ion coordinated to the pro-S nonbridging phosphate. The metal ion should in fact be bound by the pro-R oxygens of these phosphates, as is now shown

  13. Properties of the triplet metastable states of the alkaline-earth-metal atoms

    SciTech Connect

    Mitroy, J.; Bromley, M.W.J.

    2004-11-01

    The static and dynamic properties of the alkaline-earth-metal atoms in their metastable state are computed in a configuration interaction approach with a semiempirical model potential for the core. Among the properties determined are the scalar and tensor polarizabilities, the quadrupole moment, some of the oscillator strengths, and the dispersion coefficients of the van der Waals interaction. A simple method for including the effect of the core on the dispersion parameters is described.

  14. Probing the Kondo lattice model with alkaline-earth-metal atoms

    SciTech Connect

    Foss-Feig, Michael; Hermele, Michael; Rey, Ana Maria

    2010-05-15

    We study transport properties of alkaline-earth-metal atoms governed by the Kondo lattice Hamiltonian plus a harmonic confining potential, and suggest simple dynamical probes of several different regimes of the phase diagram that can be implemented with current experimental techniques. In particular, we show how Kondo physics at strong coupling, at low density, and in the heavy fermion phase is manifest in the dipole oscillations of the conduction band upon displacement of the trap center.

  15. Formation of an integrated holding company to produce rare-earth metal articles

    NASA Astrophysics Data System (ADS)

    Bogdanov, S. V.; Grishaev, S. I.

    2013-12-01

    The possibility of formation of a Russian holding company for the production of rare-earth metal articles under conditions of its increasing demand on the world market is considered. It is reasonable to ensure stable business operation on the market under conditions of state-private partnership after the fraction of soled products is determined and supported by the competitive advantages of Russian products.

  16. Lithium-Ion Batteries Being Evaluated for Low-Earth-Orbit Applications

    NASA Technical Reports Server (NTRS)

    McKissock, Barbara I.

    2005-01-01

    The performance characteristics and long-term cycle life of aerospace lithium-ion (Li-ion) batteries in low-Earth-orbit applications are being investigated. A statistically designed test using Li-ion cells from various manufacturers began in September 2004 to study the effects of temperature, end-of-charge voltage, and depth-of-discharge operating conditions on the cycle life and performance of these cells. Performance degradation with cycling is being evaluated, and performance characteristics and failure modes are being modeled statistically. As technology improvements are incorporated into aerospace Li-ion cells, these new designs can be added to the test to evaluate the effect of the design changes on performance and life. Cells from Lithion and Saft have achieved over 2000 cycles under 10 different test condition combinations and are being evaluated. Cells from Mine Safety Appliances (MSA) and modules made up of commercial-off-the-shelf 18650 Li-ion cells connected in series/parallel combinations are scheduled to be added in the summer of 2005. The test conditions include temperatures of 10, 20, and 30 C, end-of-charge voltages of 3.85, 3.95, and 4.05 V, and depth-of-discharges from 20 to 40 percent. The low-Earth-orbit regime consists of a 55 min charge, at a constant-current rate that is 110 percent of the current required to fully recharge the cells in 55 min until the charge voltage limit is reached, and then at a constant voltage for the remaining charge time. Cells are discharged for 35 min at the current required for their particular depth-of-discharge condition. Cells are being evaluated in four-cell series strings with charge voltage limits being applied to individual cells by the use of charge-control units designed and produced at the NASA Glenn Research Center. These charge-control units clamp the individual cell voltages as each cell reaches its end-of-charge voltage limit, and they bypass the excess current from that cell, while allowing the full current flow to the remaining cells in the pack. The goal of this evaluation is to identify conditions and cell designs for Li-ion technology that can achieve more than 30,000 low-Earth-orbit cycles. Testing is being performed at the Naval Surface Warfare Center, Crane Division, in Crane, Indiana.

  17. Ground-state properties of rare-earth metals: an evaluation of density-functional theory.

    PubMed

    Söderlind, Per; Turchi, P E A; Landa, A; Lordi, V

    2014-10-15

    The rare-earth metals have important technological applications due to their magnetic properties, but are scarce and expensive. Development of high-performance magnetic materials with less rare-earth content is desired, but theoretical modeling is hampered by complexities of the rare earths electronic structure. The existence of correlated (atomic-like) 4f electrons in the vicinity of the valence band makes any first-principles theory challenging. Here, we apply and evaluate the efficacy of density-functional theory for the series of lanthanides (rare earths), investigating the influence of the electron exchange and correlation functional, spin-orbit interaction, and orbital polarization. As a reference, the results are compared with those of the so-called 'standard model' of the lanthanides in which electrons are constrained to occupy 4f core states with no hybridization with the valence electrons. Some comparisons are also made with models designed for strong electron correlations. Our results suggest that spin-orbit coupling and orbital polarization are important, particularly for the magnitude of the magnetic moments, and that calculated equilibrium volumes, bulk moduli, and magnetic moments show correct trends overall. However, the precision of the calculated properties is not at the level of that found for simpler metals in the Periodic Table of Elements, and the electronic structures do not accurately reproduce x-ray photoemission spectra. PMID:25237839

  18. Calcium substitution in rare-earth metal germanides with the hexagonal Mn5Si3 structure type. structural characterization of the extended series RE5-xCaxGe3 (RE=Rare-earth metal)

    NASA Astrophysics Data System (ADS)

    Suen, Nian-Tzu; Broda, Matthew; Bobev, Svilen

    2014-09-01

    Reported are the synthesis and the structural characterization of an extended family of rare-earth metal-germanides with a general formula RE5-xCaxGe3 (RE=Y, Ce-Nd, Sm, Gd-Tm and Lu; x<2). All twelve phases are isotypic, crystallizing with the Mn5Si3 structure type (Pearson index hP16, hexagonal space group P63/mcm); they are the Ca-substituted variants of the corresponding RE5Ge3 binaries. Across the series, despite some small variations in the Ca-uptake, the unit cell volumes decrease monotonically, following the lanthanide contraction. Temperature dependent DC magnetization measurements reveal paramagnetic behavior in the high temperature range, and the obtained effective moments are consistent with free-ion RE3+ ground state, as expected from prior studies of the binary RE5Ge3 phases. The onset of magnetic ordering is observed in the low temperature range, and complex magnetic interactions (ferromagnetic/ferrimagnetic) can be inferred, different from the binary phases RE5Ge3, which are known as antiferromagnetic. In order to understand the role of Ca in the bonding, the electronic structures of the La5Ge3 and the hypothetical compounds La2Ca3Ge3 and La3Ca2Ge3 with ordered metal atoms are compared and discussed.

  19. Computational scheme for the prediction of metal ion binding by a soil fulvic acid

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.; Ephraim, J.H.; Mathuthu, A.S.

    1995-01-01

    The dissociation and metal ion binding properties of a soil fulvic acid have been characterized. Information thus gained was used to compensate for salt and site heterogeneity effects in metal ion complexation by the fulvic acid. An earlier computational scheme has been modified by incorporating an additional step which improves the accuracy of metal ion speciation estimates. An algorithm is employed for the prediction of metal ion binding by organic acid constituents of natural waters (once the organic acid is characterized in terms of functional group identity and abundance). The approach discussed here, currently used with a spreadsheet program on a personal computer, is conceptually envisaged to be compatible with computer programs available for ion binding by inorganic ligands in natural waters.

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

    SciTech Connect

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

    1990-01-01

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

  1. Determination of metal ion concentrations by SERS using 2,2'-bipyridyl complexes.

    PubMed

    Docherty, Julie; Mabbott, Samuel; Smith, W Ewen; Reglinski, John; Faulds, Karen; Davidson, Christine; Graham, Duncan

    2015-10-01

    Surface enhanced Raman scattering (SERS) can generate characteristic spectral "fingerprints" from metal complexes, thus providing the potential for the development of methods of analysis for the identification and quantitation of a range of metal ions in solution. The advantages include sensitivity and the use of one ligand for several metals without the need for a specific chromophore. Aqueous solutions of Fe(II), Ni(II), Zn(II), Cu(II), Cr(III) and Cd(II) in the presence of excess 2,2'-bipyridyl (bipy) were analysed using SERS. Specific marker bands enabled the identification of each metal ion and the limit of detection for each metal ion was estimated. Two of the ions, Zn(II) and Cu(II), could be detected below the World Health Organisation's (WHO) recommended limits for drinking water at levels of 0.22 and 0.6 mg L(-1), respectively. PMID:26312259

  2. Metal ion complexation by ionizable crown ethers. Progress report, January 1, 1991--December 31, 1993

    SciTech Connect

    Bartsch, R.A.

    1993-07-01

    Cyclic and acyclic polyether compounds with pendent carboxylic acid, phosphonic acid monoethyl ester, sulfonic acid, phosphinic acid and hydroxamic acid groups have been synthesized. The proton-ionizable polyethers can come with and without lipophilic groups. Two types of lipophilic di-ionizable lariat ethers have been prepared. Conformations of proton-ionizable lariat ethers have been probed. Competitive alkali metal cation transport by syn-(decyl)dibenzo-16-crown-5-oxyacetic acid and lipophilic proton-ionizable dibenzo lariat ethers in polymer-supported liquid membranes was studied. Complexation of alkali metal cations with ionized lariat ethers was studied. Condensation polymerization of cyclic and acyclic dibenzo polyethers containing pendent mono-ionizable groups with formaldehyde produces novel ion exchange resins with both ion exchange sites for metal ion complexation and polyether binding sites for metal ion recognition. Resins prepared from lariat ether dibenzo phosphonic acid monoethyl esters show strong sorption of divalent heavy metal cations with selectivity for Pb{sup 2+}.

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

    PubMed Central

    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 resurfacing arthroplasty. Patients with implanted MoM-bearing should receive regular and standardized monitoring of metal ion concentrations. Further research is indicated especially with regard to potential systemic reactions due to accumulation of metal products. PMID:23950923

  4. Properties of microsolvated ions: from the microenvironment of chromophore and alkali metal ions in proteins to negative ions in water clusters.

    PubMed

    Nielsen, Steen Brøndsted; Andersen, Lars H

    2006-12-01

    Here we discuss the fascinating chemistry and physics of microsolvated ions that bridge the transition from bare ions in gas phase to ions in solution. Such ions occur in many situations in biochemistry and are crucial for several functions; metal ions, for example, must remove their water shell to pass through ion pumps in membranes. Furthermore, only a few water molecules are buried in the hydrophobic pockets of proteins where they are bound to charged amino acid residues or ionic chromophores. Another aspect is the reactivity of microsolvated ions and the importance in atmospheric, organic and inorganic chemistry. We close by a discussion of the stability of molecular dianions, and how hydration affects the electronic binding energy. There is a vast literature on microsolvated ions, and in this review we are far from being comprehensive, rather we mainly bring examples of our own work. PMID:16697516

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

    NASA Astrophysics Data System (ADS)

    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 revealed that the amount of metal ions being transported agreed well with the amount of colloids being mobile and the amount of metal ions being bound to the colloids. Particle mobility is strongly affected by the ionic strength of the eluent and by organic coatings. In the presence of NaCl organic coatings enhanced particle mobility, whereas in the presence of CaCl2 it was reduced.

  6. Investigation of thermal diffusivity dependence on temperature in a group of optical single crystals doped with rare earth ions

    NASA Astrophysics Data System (ADS)

    Trefon-Radziejewska, D.; Bodzenta, J.

    2015-07-01

    The group of YAG, YVO4 and GdCOB single crystals was examined to determine the thermal diffusivity as a function of temperature in range from 30 °C to 300 °C. Further investigations concerned on analysis of the influence of dopants on these dependencies. The experimental setup based on thermal wave method with mirage detection was used. The samples represented different crystallographic systems such as cubic (YAG) tetragonal (YVO4) and monoclinic (GdCOB). The anisotropy of thermal conductivity of investigated samples was taken into account in the investigations. The crystals were doped with calcium ions, rare earth ions such as ytterbium, neodymium, and thulium, and also with transition metal vanadium. The results confirmed that influence of doping on the thermal diffusivity of investigated materials strongly depends on temperature. In general the thermal diffusivity decreases with increasing of sample temperature from 30 °C to 300 °C, however the drop in thermal diffusivity is the highest for pure single crystals. Doping is another factor reducing the heat transport in single crystals. Introduction of dopant ions into a crystal lattice leads to a significant decrease in the thermal diffusivity at lower temperatures in comparison with pure crystals. However, the influence of dopants becomes less pronounced with increasing temperature, and in case of weakly doped crystals it becomes negligible at higher temperatures. The interpretation of thermal diffusivity dependence on temperature for single crystals was based on the Debye model of lattice thermal conductivity of solids. The results allowed to conclude that the decrease of thermal diffusivity with temperature and increasing concentration of impurities is caused by shortening of the phonons mean free path due to phonon-phonon and phonon-point defect scatterings.

  7. Dispersion coefficients for H and He interactions with alkali-metal and alkaline-earth-metal atoms

    SciTech Connect

    Mitroy, J.; Bromley, M.W.J.

    2003-12-01

    The van der Waals coefficients C{sub 6}, C{sub 8}, and C{sub 10} for H and He interactions with the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are determined from oscillator strength sum rules. The oscillator strengths were computed using a combination of ab initio and semiempirical methods. The dispersion parameters generally agree with close to exact variational calculations for Li-H and Li-He at the 0.1% level of accuracy. For larger systems, there is agreement with relativistic many-body perturbation theory estimates of C{sub 6} at the 1% level. These validations for selected systems attest to the reliability of the present dispersion parameters. About half the present parameters lie within the recommended bounds of the Standard and Certain compilation [J. Chem. Phys. 83, 3002 (1985)].

  8. Stochastic Growth of Ion Cyclotron And Mirror Waves In Earth's Magnetosheath

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Grubits, K. A.

    2001-01-01

    Electromagnetic ion cyclotron and mirror waves in Earth's magnetosheath are bursty, have widely variable fields, and are unexpectedly persistent, properties difficult to reconcile with uniform secular growth. Here it is shown for specific periods that stochastic growth theory (SGT) quantitatively accounts for the functional form of the wave statistics and qualitatively explains the wave properties. The wave statistics are inconsistent with uniform secular growth or self-organized criticality, but nonlinear processes sometimes play a role at high fields. The results show SGT's relevance near marginal stability and suggest that it is widely relevant to space and astrophysical plasmas.

  9. Raman Spectroscopic Characterization of Rare Earth Ions Doped Bismuth-Based Glasses

    SciTech Connect

    Pop, L.; Culea, E.; Bosca, M.; Culea, M.

    2007-04-23

    The xReO(1-x)[3Bi2O3{center_dot}PbO] glass systems with diferent rare earth ions (ReO = CeO2, Tb4O7) have been prepared and examined with the aim of determining their structural characteristics. Raman sprectroscopy and density measurements were used to characterize the samples. Raman spectroscopy data permitted to identify some of the structural units that built up the lead bismuthate vitreous network. Density data were used to calculate the Poisson's ratio in terms of the Makishima-Mackenzie model.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    The dynamics of ions in ultrafast laser ablation of metals is studied over fluences ranging from the ablation threshold up to ?75 J/cm2 by means of three well-established diagnostic techniques. Langmuir probe, Faraday cup, and spectrally resolved intensified charge coupled device imaging simultaneously monitored the ions produced during ultrafast laser ablation of a pure copper target with 800 nm, ?50 fs, Ti: Sapphire laser pulses. The fluence dependence of ion yield is analyzed, resulting in the observance of three different regimes. The specific ion yield shows a maximum at about 4-5 J/cm2, followed by a gradual reduction and a transition to a high-fluence regime above ?50 J/cm2. The fluence dependence of the copper ions angular distribution is also analyzed, observing a gradual increase in forward-peaking of Cu ions for fluences up to ?10 J/cm2. A broader ion component is observed at larger angles for fluences larger than ?10 J/cm2. Finally, an experimental characterization of the ionic angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ?66 J/cm2. Interestingly, the ion emission from the volatile metals shows a narrow, forward-peaked distribution, and a high peak ion yield compared to the refractory metals. Moreover, the width of ionic angular distributions presents a striking correlation with the peak ion yield.

  11. Direct observation of ion transfer in contact charging between a metal and a polymer

    NASA Astrophysics Data System (ADS)

    Mizes, H. A.; Conwell, E. M.; Salamida, D. P.

    1990-04-01

    Triboelectric charging between metals and insulators is usually thought to involve electron transfer. Doping some polymers with a small amount of salt can significantly change their charging properties, even reversing the sign to which they charge upon contact with a given metal. We show by means of secondary-ion mass spectrometry that ions of the salt are transferred across the interface in contacts between a doped polymer and a metal. Specifically, we observe a transfer of bromine ions when polystyrene doped with a small amount of the salt cetylpyridinium bromide is contacted to an indium surface.

  12. Ion implantation of rare-earth dopants in ferromagnetic thin films

    SciTech Connect

    Dasgupta, V.; Litombe, N.; Bailey, W. E.; Bakhru, H.

    2006-04-15

    We show that high-dose ion implantation can be used to introduce rare-earth dopants for the control of precessional dynamics in magnetic thin films. Tb and Gd ions have been implanted in Ni{sub 81}Fe{sub 19} through Ta masks at dosages from 1x10{sup 14}/cm{sup 2} to 1x10{sup 15}/cm{sup 2}. Effects on dynamics are found to be similar to those contributed by cosputtered Tb and Gd dopants in Ni{sub 81}Fe{sub 19} (50 nm). Broadband ferromagnetic resonance measurements from 0 to 18 GHz show that adjustments in damping {alpha} from 0.008 to 0.040 are fully intrinsic (Gilbert type) and roughly proportional to dose. The technique enables the creation of films with spatially modulated precessional characteristics.

  13. Interactions of microorganisms with rare earth ions and their utilization for separation and environmental technology.

    PubMed

    Moriwaki, Hiroshi; Yamamoto, Hiroki

    2013-01-01

    In recent years, rare earth elements (REEs) have been widely used in various modern technological devices and the global demand for REE has been increasing. The increased demand for REEs has led to environmental exposure or water pollution from rare earth metal mines and various commercial products. Therefore, the development of a safe technology for the separation and adsorption of REEs is very important from the perspective of green chemistry and environmental pollution. In this review, the application and mechanisms of microorganisms for the removal and extraction of REEs from aqueous solutions are described. In addition, the advantages in using microorganisms for REE adsorption and future studies on this topic are discussed. PMID:23111596

  14. Source of seed fluctuations for electromagnetic ion cyclotron waves in Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Gamayunov, K. V.; Engebretson, M. J.; Zhang, M.; Rassoul, H. K.

    2015-06-01

    We consider a nonlinear wave energy cascade from the low frequency range into the higher frequency domain of electromagnetic ion cyclotron (EMIC) wave generation as a possible source of seed fluctuations for EMIC wave growth due to the ion cyclotron instability in Earth's magnetosphere. The presented theoretical analysis shows that energy cascade from the Pc 4-5 frequency range (2-22 mHz) into the range of Pc 1-2 pulsations (0.1-5 Hz), i.e. into the frequency range of EMIC waves, is able to supply the needed level of seed fluctuations that guarantees growth of EMIC waves up to the observable level during one pass through the near equatorial region where the ion cyclotron instability takes place. We also analyze the magnetic field data from the Polar and Van Allen Probes spacecraft to test the suggested nonlinear mechanism. In this initial study we restrict our analysis to magnetic fluctuation spectra only. We do not analyze the third-order structure function, but judge whether a nonlinear energy cascade is present or whether it is not by only analyzing the appearance of power-law distributions in the low-frequency part of the magnetic field spectra. While the power-law spectrum alone does not guarantee that a nonlinear cascade is present, the power-law distribution is a strong indication of the possible development of a nonlinear cascade. Our analysis shows that a nonlinear energy cascade is indeed observed in both the outer and inner magnetosphere data, and EMIC waves are growing from this nonthermal background. All the analyzed data are in good agreement with the theoretical model presented in this study. Overall, the results of this study support a nonlinear energy cascade in Earth's magnetosphere as a mechanism which is responsible for supplying seed fluctuating energy in the higher frequency domain where EMIC waves grow due to the ion cyclotron instability.

  15. Novel Metal Ion Based Estrogen Mimics for Molecular Imaging

    SciTech Connect

    Rajagopalan, Raghavan

    2006-01-30

    The overall objective of the SBIR Phase I proposal is to prepare and evaluate a new class of {sup 99m}Tc or {sup 94m}Tc containing estrogen-like small molecules ('estrogen mimics') for SPECT or PET molecular imaging of estrogen receptor positive (ER+) tumors. In this approach, the metal ion is integrated into the estrone skeleton by isosteric substitution of a carbon atom in the steroidal structure to give new class of mimics that are topologically similar to the native estrogen (Fig. 1). Although both N{sub 2}S{sub 2} and N{sub 3}S mimics 1 and 2 were considered as target structures, molecular modeling study revealed that the presence of the acetyl group at position-15 in the N{sub 3}S mimic 2 causes steric hinderance toward binding of 2 to SHBG. Therefore, initial efforts were directed at the synthesis and evaluation of the N{sub 2}S{sub 2} mimic 1.

  16. Interaction between ATP, metal ions, glycine, and several minerals

    NASA Technical Reports Server (NTRS)

    Rishpon, J.; Ohara, P. J.; Lawless, J. G.; Lahav, N.

    1982-01-01

    Interactions between ATP, glycine and montmorillonite and kaolinite clay minerals in the presence of various metal cations are investigated. The adsorption of adenine nucleotides on clays and Al(OH)3 was measured as a function of pH, and glycine condensation was followed in the presence of ATP, ZnCl2, MgCl2 and either kaolinite or montmorillonite. The amounts of ATP and ADP adsorbed are found to decrease with increasing Ph, and to be considerably enhanced in experiments with Mg(2+)- and Zn(2+)-montmorillonite with respect to Na(+)-montmorillonite. The effects of divalent cations are less marked in kaolinite. Results for Al(OH)3 show the importance of adsorption at clay platelet edges at high pH. The decomposition of ATP during drying at high temperature is observed to be inhibited by small amounts of clay, vacuum, or Mg(2+) or Zn(2+) ions, and to be accompanied by peptide formation in the presence of glycine. Results suggest the importance of Zn(2+) and Mg(2+) in chemical evolution.

  17. Rare earth elements and critical metal content of extracted landfilled material and potential recovery opportunities.

    PubMed

    Gutiérrez-Gutiérrez, Silvia C; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart

    2015-08-01

    Rare earth elements (REEs), Platinum group metals (PGMs) and other critical metals currently attract significant interest due to the high risks of supply shortage and substantial impact on the economy. Their uses in many applications have made them present in municipal solid waste (MSW) and in commercial and industrial waste (C&I), since several industrial processes produce by-products with high content of these metals. With over 4000 landfills in the UK alone, the aim of this study was to assess the existence of these critical metals within landfills. Samples collected from four closed landfills in UK were subjected to a two-step acid digestion to extract 27 metals of interest. Concentrations across the four landfill sites were 58±6mgkg(-1) for REEs comprising 44±8mgkg(-1) for light REEs, 11±2mgkg(-1) for heavy REEs and 3±1mgkg(-1) for Scandium (Sc) and 3±1.0mgkg(-1) of PGMs. Compared to the typical concentration in ores, these concentrations are too low to achieve a commercially viable extraction. However, content of other highly valuable metals (Al and Cu) was found in concentrations equating to a combined value across the four landfills of around $400 million, which increases the economic viability of landfill mining. Presence of critical metals will mainly depend on the type of waste that was buried but the recovery of these metals through landfill mining is possible and is economically feasible only if additional materials (plastics, paper, metallic items and other) are also recovered for reprocessing. PMID:25957938

  18. Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue

    DOEpatents

    Sharp, David W. (Seabrook, TX)

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about 249.degree. F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  19. Sungrazing comets as source of pickup ions at Earth orbit and Ulysses

    E-print Network

    M. Bzowski; M. Krolikowska

    2005-07-04

    Most of the sungrazing comets observed by LASCO at SOHO belong to the Kreutz group of comets and follow trajectories that are tightly clumped in space. Statistical analysis of 9 years of SOHO observations suggests that the true apparition rate of these comets is as high as one every other day. Practically all these comets break up before perihelion passage. Their material is dissociated and ionized, and subsequently transported away from the Sun as pickup ions in the solar wind. Their mean mass flux is about $3.1 10^4 g/s. Since the breakup occurs between 40 and 4 solar radii and the ionization is almost immediate, the expected location of these ions in the phase space is close to the location of the inner source of pickup ions. Assuming radial propagation, the cometary pickups should be observable at Earth between August and January, with peak probability at the end of September. At Ulysses, they should be observable approximately between -25 and 40 degrees ecliptic latitude during the fast latitude scans, the first of which occurred in 1995 and the second in 2001. The population of cometary pickup ions should be augmented by about 40% by solar wind protons as a result of charge exchange with the cometary neutral hydrogen and oxygen atoms and subsequent reionization of the newly-created Energetic Neutral Atoms, streaming with respect to the solar wind. In total, the average flux of the pickup ions related to the sungrazing comets at 1 AU should be about 1.6 10^5 g/s/sr within the detection area (and null outside it). This value is comparable to the flux of the inner source-pickup ions.

  20. Statistical analysis of diffuse ion events upstream of the Earth's bow shock

    NASA Technical Reports Server (NTRS)

    Trattner, K. J.; Mobius, E.; Scholer, M.; Klecker, B.; Hilchenbach, M.; Luehr, H.

    1994-01-01

    A statistical study of diffuse energetic ion events and their related waves upstream of the Earth's bow shock was performed using data from the Active Magnetospheric Particle Tracer Explorers/Ion Release Module (AMPTE/IRM) satellite over two 5-month periods in 1984 and 1985. The data set was used to test the assumption in the self-consistent model of the upstream wave and particle populations by Lee (1982) that the particle acceleration through hydromagnetic waves and the wave generation are directly coupled. The comparison between the observed wave power and the wave power predicted on the observed energetic particle energy density and solar wind parameters results in a high correlation coefficient of about 0.89. The intensity of diffuse ions falls off approximately exponentially with the distance upstream from the bow shock parallel to the magnetic field with e-folding distances which vary from approximately 3.3 R(sub E) to approximately 11.7 R(sub E) over the energy range from 10 keV/e to 67.3 keV/e for both protons and alpha particles. After normalizing the upstream particle densities to zero bow shock distance by using these exponential variations, a good correlation (0.7) of the density of the diffuse ions with the solar wind density was found. This supports the suggestion that the solar wind is the source of the diffuse ions. Furthermore, the spectral slope of the diffuse ions correlates well with the solar wind velocity component in the direction of the interplanetary magnetic field (0.68 and 0.66 for protons and alpha particles) which concurs with the notion that the solar wind plays an important role in the acceleration of the upstream particles.

  1. How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

    NASA Astrophysics Data System (ADS)

    Kam, K.; Lemke, K.

    2014-12-01

    The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with results from molecular simulations of metal halides that are aimed at characterizing the nature (i.e. relativistic structures and energies) of metal clusters in water vapor.

  2. Optical probes for the detection of protons, and alkali and alkaline earth metal cations.

    PubMed

    Hamilton, Graham R C; Sahoo, Suban K; Kamila, Sukanta; Singh, Narinder; Kaur, Navneet; Hyland, Barry W; Callan, John F

    2015-07-01

    Luminescent sensors and switches continue to play a key role in shaping our understanding of key biochemical processes, assist in the diagnosis of disease and contribute to the design of new drugs and therapies. Similarly, their contribution to the environment cannot be understated as they offer a portable means to undertake field testing for hazardous chemicals and pollutants such as heavy metals. From a physiological perspective, the Group I and II metal ions are among the most important in the periodic table with blood plasma levels of H(+), Na(+) and Ca(2+) being indicators of several possible disease states. In this review, we examine the progress that has been made in the development of luminescent probes for Group I and Group II ions as well as protons. The potential applications of these probes and the mechanism involved in controlling their luminescent response upon analyte binding will also be discussed. PMID:25742963

  3. Influence of rare earth metals on the nucleation and solidification behavior of iron and 1045 steel

    NASA Astrophysics Data System (ADS)

    Li, H.; McLean, A.; Rutter, J. W.; Sommerville, I. D.

    1988-06-01

    Two series of experiments have been conducted to determine the influence of rare earth additions on the nucleation and crystallization behavior of pure iron and 1045 steel. In the first series, additions of rare earth suicide or cerium dioxide powder to two-Kg 1045 steel ingots indicated that rare earth suicide can refine the as-cast structure of such ingots. However, if the holding time after rare earth silicide addition is over two minutes, the grain refinement decreases. With cerium dioxide additions, a relatively large columnar zone was obtained. In the second series, the effects of cerium metal or cerium dioxide powder additions on the degree of undercooling obtainable in pure iron and 1045 steel were examined by the lévitation melting method. Surface tension measurements of the levitated droplets were carried out at the same time to investigate the possible effects of surface tension variations on the nucleation and crystallization behavior of the metals. The experimental data show that rare earth inclusions can greatly reduce the degree of undercooling of iron and steel, and that a small amount of dissolved cerium can further reduce the degree of undercooling of levitated droplets. The structure and reaction products obtained with Fe-Ce levitated droplets were examined with both optical and scanning electron microscopy as well as X-ray diffraction analysis. The experimental results clearly indicated that cerium solute redistribution during solidification is the dominant factor in refining the as-cast structure. A nucleation and solidification model for the Fe-Ce levitated droplets has been developed, which can successfully explain the experimental results.

  4. Cross-reactive fluorescent indicators for analysis of metal-ion mixtures

    SciTech Connect

    Chadha, S.; Tabacco, M.B.; Walt, D.R.

    1997-12-31

    The conventional approach to optical sensing of metal ions has been to use metal-binding indicators containing selective binding sites linked to a chromogenic or fluorescent tag. The one analyte-one sensor approach tends to be tedious and time consuming, especially where multiple ions need to be determined. Most metallofluorescent indicators lack sufficient binding discrimination between metal ions to be effective for analysis of mixtures. In this paper we present an approach which exploits the cross-reactivity of semi-selective metallofluorescent indicators, combined with multivariate analysis, to model a binding pattern for multiple metal ions. Mixtures of metal ions have different cross-reactive binding patterns with each metallofluorescent indicator. A pattern recognition algorithm capable of modeling these binding patterns allows concentrations of individual metal ions to be determined. The fluorescence responses of the indicators and formation of the metal complexes are pH dependent, therefore calibration was performed at different pH values in the 4-9 pH range. The application of these semi-selective indicators to the development of optical array sensors for continuous, on-site monitoring in multicomponent media is discussed is a useful alternative to the one analyte-one sensor paradigm.

  5. Elastomeric Nanocomposite Foams for the Removal of Heavy Metal Ions from Water.

    PubMed

    Chavan, Asmita A; Li, Hongbo; Scarpellini, Alice; Marras, Sergio; Manna, Liberato; Athanassiou, Athanassia; Fragouli, Despina

    2015-07-15

    We report the fabrication and utilization of elastomeric polymer nanocomposite foams for the efficient removal of Pb2+ and Hg2+ heavy metal ions from polluted water. The polydimethylsiloxane (PDMS) foams are properly modified in order to become hydrophilic and allow the polluted water to penetrate in their volume. The ZnSe colloidal nanocrystals (NCs) that decorate the surface of the foams, act as active components able to entrap the metal ions. In this way, after the dipping of the nanocomposite foams in water polluted with Pb2+ or Hg2+, a cation exchange reaction takes place, and the heavy metal ions are successfully removed. The removal capacity for the Pb2+ ions exceeds 98% and the removal of Hg2+ ions approaches almost 100% in the studied concentrations region of 20-40 ppm. The reaction is concluded after 24 h, but it should be noticed that after the first hour, more than 95% of both the metal ions is removed. The color of the foams changes upon heavy metal ions entrapment, providing thus the opportunity of an easy detection of the presence of the ions in water. Taking into account that the fabricated foams provide good elastic properties and resistance to heat, they can be used in different conditions of water remediation. PMID:26133912

  6. he Ion Beam Materials Laboratory (IBML) is a Los Alamos National Laboratory resource devoted to materi-

    E-print Network

    , and rare earth metals with a beam current ranging from microamperes to hundreds microamperes, deuterium, and tri- tium) to metal ratios in metal hydrides as well as oxygen depth profiles in metal kV production ion implanter Capable of producing many ion species from gases, transition metals

  7. Alkali or alkaline earth metal promoted catalyst and a process for methanol synthesis using alkali or alkaline earth metals as promoters

    DOEpatents

    Tierney, John W. (Pittsburgh, PA); Wender, Irving (Pittsburgh, PA); Palekar, Vishwesh M. (Pittsburgh, PA)

    1995-01-01

    The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a heterogeneous catalyst comprising reduced copper chromite impregnated with an alkali or alkaline earth metal. There is thus no need to add a separate alkali or alkaline earth compound. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

  8. Alkali or alkaline earth metal promoted catalyst and a process for methanol synthesis using alkali or alkaline earth metals as promoters

    DOEpatents

    Tierney, J.W.; Wender, I.; Palekar, V.M.

    1995-01-31

    The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a heterogeneous catalyst comprising reduced copper chromite impregnated with an alkali or alkaline earth metal. There is thus no need to add a separate alkali or alkaline earth compound. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100--160 C and the pressure range of 40--65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H[sub 2]/CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

  9. Heterogeneous processes affecting metal ion transport in the presence of organic ligands: Reactive transport modeling

    NASA Astrophysics Data System (ADS)

    Kantar, Cetin

    2007-04-01

    The development of models to accurately simulate metal ion transport through saturated systems under variable chemical conditions, e.g., in systems containing organic ligands (L) such as natural organic matter (NOM), has two essential aspects: (1) establishing the ability to simulate metal ion sorption to aquifer solids over a range of metal/ligand ratios; and (2) to incorporate this ability to simulate metal speciation over a range in chemical conditions (e.g., pH, ligand activity) into mass transport models. Modeling approaches to evaluate metal ion sorption and transport in the presence of NOM include: (1) isotherm-based transport models, and (2) multicomponent (MC) transport models. The accuracy of transport models depends on how well the chemical interactions affecting metal ion transport in the presence of organic ligands (e.g., metal/ligand complexation) are described in transport equations. The isotherm-based transport models often fail to accurately describe metal ion transport in the presence of NOM since these models treat NOM as a single solute despite the fact that NOM is a multicomponent mixture of subcomponents with different chemical and polyfunctional behavior. On the other hand, the calculations presented in this study suggest that a multicomponent reactive transport model, in conjunction with a mechanistic modeling approach for the description of metal ion binding by NOM in a manner conducive to the application of surface complexation modeling (SCM), can effectively be used as an important predictive tool in simulating metal ion sorption and transport under variable chemical conditions in the presence of NOM.

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

    PubMed Central

    2013-01-01

    Background and purpose 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. Methods Studies were searched for in the Medline database, Embase, and the Cochrane Database of Systematic Reviews. Highest mean or median ion concentrations of Cr and Co after a minimum of 1 year of follow-up were extracted and grouped according to sample- and articulation type, and average values were calculated. Results 43 studies were included and 16 different MoM implants were identified. For the different types of bearings, average ion concentrations and range were calculated from the mean or median ion concentration. The average Cr concentration ranged between 0.5 and 2.5 ?g/L in blood and between 0.8 and 5.1 ?g/L in serum. For Co, the range was 0.7–3.4 ?g/L in blood and 0.3–7.5 ?g/L in serum. Interpretation When the average blood ion concentrations calculated for the different implants, together with the concentrations measured in the individual studies, were compared with the upper acceptable limit for Cr and Co in blood, no clear pattern was recognized. Furthermore, we were unable to detect any clear difference in ion concentrations between different types of implants (THA and resurfacing). PMID:23594249

  11. Plastic flow produced by single ion impacts on metals.

    SciTech Connect

    Birtcher, R. C.

    1998-10-30

    Single ion impacts have been observed using in situ transmission electron microscopy and video recording with a time resolution of 33 milliseconds. Gold was irradiated at 50 K and room temperature. Single ion impacts produce holes, modify existing holes, and extrude material into the initial specimen hole and holes formed by other ion impacts. The same behavior is observed at both temperatures. At both temperatures, ion impacts result in craters and ejected material. Ion impacts produce more small craters than large ones for all ion masses, while heavier mass ions produce more and larger craters than lighter mass ions. This comparison is affected by the ion energy. As the energy of an ion is increased, the probability for deposition near the surface decreases and fewer craters are formed. For a given ion mass, crater production depends on the probability for displacement cascade production in the near surface region. Crater and holes are stable at room temperature, however, ion impacts near an existing crater may cause flow of material into the crater either reshaping or annihilating it. Holes and craters result from the explosive outflow of material from the molten zone of near-surface cascades. The outflow may take the form of molten material, a solid lid or an ejected particle. The surface is a major perturbation on displacement cascades resulting from ion impacts.

  12. Journal of Molecular Structure 890 (2008) 289294 The linkage between ribosomal crystallography, metal ions,

    E-print Network

    Yonath, Ada E.

    2008-01-01

    Journal of Molecular Structure 890 (2008) 289­294 The linkage between ribosomal crystallography linkage between ribosomal crystallography, metal ions, heteropolytungstates and functional flexibility Accepted 19 March 2008 Available online 7 April 2008 Keywords: Ribosome Ribosomal functional flexibility

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

    PubMed

    P?kal, Anna; Pyrzynska, Krystyna

    2015-02-01

    The 2,2'-diphenyl-1-picrylhydrazyl (DPPH) assay is commonly applied for the estimation of antioxidant activity of plant extracts. This article discusses the effect of a sample pH and the presence of metal ions on the results obtained using DPPH method for several tea infusions. Higher radical quenching was observed in less acidic media. The impact of metal ions depends of the types of metal ion and its concentration. Quercetin and epigallocatechin gallate were less efficient in the reaction with DPPH in the presence of Al(III). Desalting process using cation-exchange resin Dowex 50Wx8 decreased the content of metal ions in all studied tea infusions. The DPPH scavenging activity of the effluents after this process were higher than those of the primary extracts and this may be related to the actual antioxidant capacity of these samples. PMID:25578761

  14. The atmospheric circulation of the super Earth GJ 1214b: Dependence on composition and metallicity

    E-print Network

    Kataria, Tiffany; Fortney, Jonathan J; Marley, Mark S; Freedman, Richard S

    2014-01-01

    We present three-dimensional atmospheric circulation models of GJ 1214b, a 2.7 Earth-radius, 6.5 Earth-mass super Earth detected by the MEarth survey. Here we explore the planet's circulation as a function of atmospheric metallicity and atmospheric composition, modeling atmospheres with a low mean-molecular weight (i.e., H2-dominated) and a high mean-molecular weight (i.e. water- and CO2-dominated). We find that atmospheres with a low mean-molecular weight have strong day-night temperature variations at pressures above the infrared photosphere that lead to equatorial superrotation. For these atmospheres, the enhancement of atmospheric opacities with increasing metallicity lead to shallower atmospheric heating, larger day-night temperature variations and hence stronger superrotation. In comparison, atmospheres with a high mean-molecular weight have larger day-night and equator-to-pole temperature variations than low mean-molecular weight atmospheres, but differences in opacity structure and energy budget lead ...

  15. Factorial experimental design for recovering heavy metals from sludge with ion-exchange resin.

    PubMed

    Lee, I Hsien; Kuan, Yu-Chung; Chern, Jia-Ming

    2006-12-01

    Wastewaters containing heavy metals are usually treated by chemical precipitation method in Taiwan. This method can remove heavy metals form wastewaters efficiently, but the resultant heavy metal sludge is classified as hazardous solid waste and becomes another environmental problem. If we can remove heavy metals from sludge, it becomes non-hazardous waste and the treatment cost can be greatly reduced. This study aims at using ion-exchange resin to remove heavy metals such as copper, zinc, cadmium, and chromium from sludge generated by a PCB manufacturing plant. Factorial experimental design methodology was used to study the heavy metal removal efficiency. The total metal concentrations in the sludge, resin, and solution phases were measured respectively after 30 min reaction with varying leaching agents (citric acid and nitric acid); ion-exchange resins (Amberlite IRC-718 and IR-120), and temperatures (50 and 70 degrees C). The experimental results and statistical analysis show that a stronger leaching acid and a higher temperature both favor lower heavy metal residues in the sludge. Two-factors and even three-factor interaction effects on the heavy metal sorption in the resin phase are not negligible. The ion-exchange resin plays an important role in the sludge extraction or metal recovery. Empirical regression models were also obtained and used to predict the heavy metal profiles with satisfactory results. PMID:16843592

  16. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    SciTech Connect

    Mi-Kyung Han

    2006-05-01

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  17. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    SciTech Connect

    Han, M.K.

    2006-05-06

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  18. Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters

    E-print Network

    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).

  19. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-01

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

  20. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma.

    PubMed

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-01

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas. PMID:23464206

  1. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma

    SciTech Connect

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-15

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

  2. Importance of diffuse metal ion binding to RNA.

    PubMed

    Tan, Zhi-Jie; Chen, Shi-Jie

    2011-01-01

    RNAs are highly charged polyanionic molecules. RNA structure and function are strongly correlated with the ionic condition of the solution. The primary focus of this article is on the role of diffusive ions in RNA folding. Due to the long-range nature of electrostatic interactions, the diffuse ions can contribute significantly to RNA structural stability and folding kinetics. We present an overview of the experimental findings as well as the theoretical developments on the diffuse ion effects in RNA folding. This review places heavy emphasis on the effect of magnesium ions. Magnesium ions play a highly efficient role in stabilizing RNA tertiary structures and promoting tertiary structural folding. The highly efficient role goes beyond the mean-field effect such as the ionic strength. In addition to the effects of specific ion binding and ion dehydration, ion-ion correlation for the diffuse ions can contribute to the efficient role of the multivalent ions such as the magnesium ions in RNA folding. PMID:22010269

  3. Liquid-liquid extraction of europium(III) and other trivalent rare-earth ions using a non-fluorinated functionalized ionic liquid.

    PubMed

    Rout, Alok; Binnemans, Koen

    2014-01-28

    A new non-fluorinated malonamide-based ionic liquid extractant was synthesized and investigated for the extraction behavior of europium(III) and other trivalent rare-earth ions from nitric acid medium. The extractant was the functionalized ionic liquid trihexyl(tetradecyl)phosphonium N,N,N',N'-tetra(2-ethylhexyl)malonate, [P66614][MA], and it was used in combination with the non-fluorinated ionic liquid trihexyl(tetradecyl)phosphonium nitrate, [P66614][NO3], as diluents. The extraction behavior of europium in this ionic liquid solution was studied as a function of various parameters such as the pH, concentration of the extractant, the type of acidic medium, temperature, concentration of the salting-out agent and the metal concentration of the aqueous feed. The extraction behavior of [P66614][MA] in [P66614][NO3] was compared with that of [P66614][MA] in the chloride-containing ionic liquid diluent trihexyl(tetradecyl)phosphonium chloride, [P66614][Cl] (Cyphos IL 101). The nitrate system was found to be superior. Marked differences in extraction behavior were observed between [P66614][MA] and the molecular malonamide extractant N,N,N',N'-tetra(2-ethylhexyl)malonamide (TEHMA), i.e. the compound from which the anion of the ionic liquid extractant was prepared. The extraction behavior of other rare earths (La, Ce, Nd, Sm, Ho, Yb) and some transition metals (Ni, Co, Zn) was investigated using this functionalized ionic liquid. A good separation of the rare earths from the transition metals could be achieved. For the rare earths, the extraction efficiency increases over the lanthanide series. The effects of thermodynamic parameters, the stripping of europium(iii) from the ionic liquid and the reusability of the functionalized ionic liquid were studied in detail. PMID:24257814

  4. High-pressure metallization of FeO and implications for the earth's core

    NASA Technical Reports Server (NTRS)

    Knittle, Elise; Jeanloz, Raymond

    1986-01-01

    The phase diagram of FeO has been experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock-wave and diamond-cell techniques. A metallic phase of FeO is observed at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the earth's outer core, in accord with the geochemical predictions of Ringwood (1977 and 1979). The high pressures necessary for this metallization suggest that the core has acquired its composition well after the initial stages of the earth's accretion. Direct experimental observations at elevated pressures and temperatures indicate that core-forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core-mantle boundary is likely to be a zone of active chemical reactions.

  5. Moderate pressure synthesis of rare earth nickelate with metal-insulator transition using polymeric precursors

    SciTech Connect

    Napierala, C.; Lepoittevin, C.; Edely, M.; Sauques, L.; Giovanelli, F.; Laffez, P.; VanTedeloo, G.

    2010-07-15

    Rare earth nickelates exhibit a reversible metal-semiconductor phase transition that is, in the infrared range, responsible for a thermo-optical contrast. The state of the art synthesis of these compounds usually requires high oxygen pressure to stabilize Ni in the oxidation state 3{sup +}. In this work, using polymeric precursor associated with moderate pressure annealing, we show that it is possible to obtain fully oxidized rare earth nickelate with metal-insulator transition. Using thermogravimetric analysis, X-ray diffraction and transmission electronic microscopy we compare different samples synthesized at different oxygen pressures and demonstrate their structural similarity. Thermo-optical properties were measured, in the infrared range, using reflectance measurements and confirmed the metal-insulator transition at 60 {sup o}C in both samples.TEM observations lead to the conclusion that the structure commonly obtained at 175 bar is perfectly observed in the 20 bar sample without major structural defects. The two samples exhibit a thermochromic behavior and thermo-optical properties of the two samples are equivalent. - Graphical Abstract: Thermochromic behavior of Nd{sub 0.3}Sm{sub 0.7}NiO{sub 3} samples annealed under 20 and 175 bar at 278 and 373 K.

  6. High-energy metal ion implantation for reduction of surface resistivity of alumina ceramic

    SciTech Connect

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

    2012-02-15

    In this work, the possibility to increase the surface conductivity of ceramic insulators through their treatment with accelerated metal ion beams produced by a MevvaV.Ru vacuum arc source is demonstrated. The increase in surface conductivity is made possible due to experimental conditions in which an insulated collector is charged by beam ions to a potential many times lower than the accelerating voltage, and hence, than the average beam ion energy. The observed effect of charge neutralization of the accelerated ion beam is presumably associated with electrons knocked out of the electrodes of the accelerating system of the source and of the walls of the vacuum chamber by the accelerated ions.

  7. Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

    NASA Astrophysics Data System (ADS)

    Duncan, Michael

    2006-03-01

    Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

  8. Effects of metal ions on the catalytic degradation of dicofol by cellulase.

    PubMed

    Zhai, Zihan; Yang, Ting; Zhang, Boya; Zhang, Jianbo

    2015-07-01

    A new technique whereby cellulase immobilized on aminated silica was applied to catalyze the degradation of dicofol, an organochlorine pesticide. In order to evaluate the performance of free and immobilized cellulase, experiments were carried out to measure the degradation efficiency. The Michaelis constant, Km, of the reaction catalyzed by immobilized cellulase was 9.16 mg/L, and the maximum reaction rate, Vmax, was 0.40 mg/L/min, while that of free cellulase was Km=8.18 mg/L, and Vmax=0.79 mg/L/min, respectively. The kinetic constants of catalytic degradation were calculated to estimate substrate affinity. Considering that metal ions may affect enzyme activity, the effects of different metal ions on the catalytic degradation efficiency were explored. The results showed that the substrate affinity decreased after immobilization. Monovalent metal ions had no effect on the reaction, while divalent metal ions had either positive or inhibitory effects, including activation by Mn2+, reversible competition with Cd2+, and irreversible inhibition by Pb2+. Ca2+ promoted the catalytic degradation of dicofol at low concentrations, but inhibited it at high concentrations. Compared with free cellulase, immobilized cellulase was affected less by metal ions. This work provided a basis for further studies on the co-occurrence of endocrine-disrupting chemicals and heavy metal ions in the environment. PMID:26141889

  9. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

    2015-12-01

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)-based metal-organic frameworks, Zn3L3(DMF)2 (1) and Zn3L3(DMA)2(H2O)3 (2) (L=4,4?-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe3+ and Al3+ by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe3+. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity.

  10. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    SciTech Connect

    Lu, Yi

    2005-06-01

    In vitro selection for DNAzymes that are catalytically active with UO22+ ions as the metal cofactor has been completed. The 10th generation pool of DNA was cloned and sequenced. A total of 84 clones were sequenced and placed into families based on sequence alignments. Selected members of each family were 5-labeled with 32P and amplified using PCR. Activity assays were conducted using the isotopically labeled DNAzymes in order to determine which sequences were the most active. The secondary structures of the two most active sequences, called Clone 13 and Clone 39, were determined using the computer program Mfold. A cleavage rate of approximately 1 min-1 in the presence of 10 uM UO22+ was observed for both clones. Clone 39 was determined to be the best candidate for truncation to create a trans-cleaving DNAzyme, based on its secondary structure. An enzyme strand, called 39E, and a substrate strand, called 39DS, were designed by truncating the cis-cleaving DNAzyme. An alternative enzyme strand, called 39Ec, was also assayed with the 39DS substrate. This strand was designed so that the two binding arms were perfectly complimentary, unlike 39E, which formed three mismatched base pairs with 39DS. Both 39E and 39Ec were found to be active, with a rate of approximately 1 min-1 in the presence of 10 uM UO22+. A preliminary UO22+ binding curve was obtained for the 39Ec/39DS trans-cleaving system. The enzyme is active with UO22+ concentrations as low as 1 nM. Based on the preliminary binding curve data, the apparent UO22+ binding constant is approximately 330 nM, and kmax is approximately 1 min-1.

  11. The use of ion flotation for detoxification of metal-contaminated waters and process effluents

    SciTech Connect

    Doyle, F.M.; Duyvesteyn, S.; Sreenivasarao, K.

    1995-12-31

    Toxic metals entering surface or ground water from sources such as metal finishing shop spills and abandoned mines can pose a significant threat to public health and the environment. Ion flotation and similar foam separation techniques show great promise for treating dilute, metal-contaminated solutions, and could also be used to treat effluents from many minerals and metallurgical processing operations prior to discharge. In ion flotation, an appropriate collector is added to the solution to form hydrophobic complexes with the metal ions. These metal-bearing species are then removed by flotation, usually with trace addition of a frother to stabilize the foam. In an effort to better understand the underlying scientific and engineering principles that determine the performance of ion flotation, the removal of Cu(II), Pb(II), Cd(II), Cr(III) and Cr(VI) has been studied using laboratory scale flotation columns in batch mode. The effects of the superficial air velocity, solution and froth height, nature of the collector, collector:metal-ion ratio, ionic strength and several frothers at low concentrations on the flotation kinetics are reported. Finally, results are presented on methods that might allow regeneration of collector and recovery of by-product metal from the foam product.

  12. The emission characteristics of an indium needle-type liquid metal ion source

    NASA Astrophysics Data System (ADS)

    Hornsey, R. I.

    1989-09-01

    Operational data for an indium needle-type liquid metal ion source are presented. Detailed comparisons are drawn between these characteristics and those of a similar gallium source. The behaviours of the two sources are found to be strikingly similar, indicating a common mechanism of ion emission.

  13. Spin{polarized electron excitation during the neutralization of He + ions in metals

    E-print Network

    Muiño, Ricardo Díez

    Spin{polarized electron excitation during the neutralization of He + ions in metals M. Alducin a R Abstract Spin{resolved electron spectra collected during the neutralization of spin{polarized He + ions as on the neutralization process itself. The interpretation of such electron spectra, however, requires a deep

  14. Short Communication Kinetics and thermodynamics of heavy metal ions sequestration onto novel

    E-print Network

    Gong, Jian Ru

    Short Communication Kinetics and thermodynamics of heavy metal ions sequestration onto novel of Cadmium and Mercury ions. " Kinetics and thermodynamics of biosorption. " Biosorption feasible, spontaneous and endothermic. a r t i c l e i n f o Article history: Received 6 January 2012 Received

  15. Titanium alloy mini-implants for orthodontic anchorage: Immediate loading and metal ion release q

    E-print Network

    Meyers, Marc A.

    Titanium alloy mini-implants for orthodontic anchorage: Immediate loading and metal ion release q devices in orthodontics. The early load is nec- essary to simplify the mini-implant methodology, but can: Titanium alloy; Mini-implant; Orthodontic anchorage; Ion release 1. Introduction Anchorage has long been

  16. Metallic LiMo3Se3 Nanowire Film Sensors for Electrical Detection of Metal Ions in Water

    E-print Network

    Osterloh, Frank

    Metallic LiMo3Se3 Nanowire Film Sensors for Electrical Detection of Metal Ions in Water Mark AllenVis, California 95616 ReceiVed February 5, 2008. ReVised Manuscript ReceiVed March 30, 2008 LiMo3Se3 nanowire film sensors were fabricated by drop-coating a 0.05% (mass) aqueous nanowire solution onto microfabricated

  17. Property enchancement of polyimide films by way of the incorporation of lanthanide metal ions

    NASA Technical Reports Server (NTRS)

    Thompson, David W.

    1993-01-01

    Lanthanide metal ions were incorporated into the polyimide derived from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 1,3-bis(aminophenoxy) benzene (APB) in an attempt to produce molecular level metal-polymer composites. The lanthanide series of metal ions (including aluminum, scandium, and yttrium) provide discrete and stable metal ions in the 3+ oxidation state. Throughout the series there is a uniform variation in ionic size ranging from 50 pm for aluminum to a maximum of 103.4 pm for cerium and gradually decreasing again to 84.8 pm for lutetium. The high charge-to-size ratio for these ions as well as the ability to obtain large coordination numbers makes them excellent candidates for interacting with the polymer substructure. The distinct lack of solubility of simple lanthanide salts such as the acetates and halides has made it difficult to obtain metal ions distributed in the polymer framework as discrete ions or metal complexes rather than microcomposites of metal clusters. (Lanthanum nitrates are quite soluble, but the presence of the strongly oxidizing nitrate ion leads to serious degradation of the polymer upon thermal curing. This work was successful at extending the range of soluble metals salts by using chelating agents derived from the beta-diketones dipivaloylmethane, dibenzoylmethane, trifluoroacetylacetone, and hexafluoroacetylacetone. Metal acetates which are insoluble in dimethylacetamide dissolve readily in the presence of the diketones. Addition of the polyimide yields a homogeneous resin which is then cast into a clear film. Upon curing clear films were obtained with the dibenzoylmethane and trifluoroacetylacetone ligands. The dipavaloylmethane precipitates the metal during the film casting process, and hexafluoroacetylacetone gives cured films which are deformed and brittle. These clear films are being evaluated for the effect of the metal ions on the coefficient of thermal expansion, resistance to atomic oxygen, and on selective gas permeability. Much more commonly than above, polyimide films are prepared by casting the film as the poly(amic acid) precursor which is then converted to the imidized form during the thermal cure cycle. Very limited success was achieved in the past in adding lanthanide metal ions to the amide precursors because of gellation and lack of solubility. With the use of the diketone ligands cited above, the solubility and gellation problems were overcome. However, the films after curing were clear but unacceptably brittle. Attempts to overcome this cure embrittlement problem are in progress.

  18. Liquefaction process for solid carbonaceous materials containing alkaline earth metal humates

    DOEpatents

    Epperly, William R. (Summit, NJ); Deane, Barry C. (East Brunswick, NJ); Brunson, Roy J. (Buffalo Grove, IL)

    1982-01-01

    An improved liquefaction process wherein wall scale and particulate agglomeration during the liquefaction of solid carbonaceous materials containing alkaline earth metal humates is reduced and/or eliminated by subjecting the solid carbonaceous materials to controlled cyclic cavitation during liquefaction. It is important that the solid carbonaceous material be slurried in a suitable solvent or diluent during liquefaction. The cyclic cavitation may be imparted via pressure cycling, cyclic agitation and the like. When pressure cycling or the like is employed an amplitude equivalent to at least 25 psia is required to effectively remove scale from the liquefaction vessel walls.

  19. Narcissistic self-sorting in self-assembled cages of rare Earth metals and rigid ligands.

    PubMed

    Johnson, Amber M; Wiley, Calvin A; Young, Michael C; Zhang, Xing; Lyon, Yana; Julian, Ryan R; Hooley, Richard J

    2015-05-01

    Highly selective, narcissistic self-sorting can be achieved in the formation of self-assembled cages of rare earth metals with multianionic salicylhydrazone ligands. The assembly process is highly sensitive to the length of the ligand and the coordination geometry. Most surprisingly, high-fidelity sorting is possible between ligands of identical coordination angle and geometry, differing only in a single functional group on the ligand core, which is not involved in the coordination. Supramolecular effects allow discrimination between pendant functions as similar as carbonyl or methylene groups in a complex assembly process. PMID:25784462

  20. Poultry litter-based activated carbon for removing heavy metal ions in water.

    PubMed

    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. PMID:19783133

  1. Coloring a Superabsorbent Polymer with Metal Ions: An Undergraduate Chemistry Experiment

    ERIC Educational Resources Information Center

    Yaung, Jing-Fun; Chen, Yueh-Huey

    2009-01-01

    A novel undergraduate chemistry experiment involving superabsorbent polymers commonly used in diapers and other personal care products is described. Students observe the removal of divalent transition-metal ions from aqueous solutions by the polymers. With the procedures provided, students are able to color the superabsorbent polymers with metal

  2. Metal ions affecting the pulmonary and cardiovascular systems.

    PubMed

    Corradi, Massimo; Mutti, Antonio

    2011-01-01

    Some metals, such as copper and manganese, are essential to life and play irreplaceable roles in, e.g., the functioning of important enzyme systems. Other metals are xenobiotics, i.e., they have no useful role in human physiology and, even worse, as in the case of lead, may be toxic even at trace levels of exposure. Even those metals that are essential, however, have the potential to turn harmful at very high levels of exposure, a reflection of a very basic tenet of toxicology--"the dose makes the poison." Toxic metal exposure may lead to serious risks to human health. As a result of the extensive use of toxic metals and their compounds in industry and consumer products, these agents have been widely disseminated in the environment. Because metals are not biodegradable, they can persist in the environment and produce a variety of adverse effects. Exposure to metals can lead to damage in a variety of organ systems and, in some cases, metals also have the potential to be carcinogenic. Even though the importance of metals as environmental health hazards is now widely appreciated, the specific mechanisms by which metals produce their adverse effects have yet to be fully elucidated. The unifying factor in determining toxicity and carcinogenicity for most metals is the generation of reactive oxygen and nitrogen species. Metal-mediated formation of free radicals causes various modifications to nucleic acids, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Whilst copper, chromium, and cobalt undergo redox-cycling reactions, for metals such as cadmium and nickel the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. This chapter attempts to show that the toxic effects of different metallic compounds may be manifested in the pulmonary and cardiovascular systems. The knowledge of health effects due to metal exposure is necessary for practising physicians, and should be assessed by inquiring about present and past occupational history and environmental exposure. PMID:21473377

  3. Selective adsorption of metal ions by chemically-modified MCM-41

    NASA Astrophysics Data System (ADS)

    Lam, Koon Fung

    Selective adsorbents were developed for removal and recovery of heavy metals from aqueous medium. As heavy metals interact with surface moieties differently depending on their chemical properties, tailor-made adsorbents were synthesized for metal separation from aqueous solution based on different adsorption mechanisms. This is the first comprehensive study in the design of adsorbent for selective adsorption of metal ions based on a nanostructured material, MCM-41. Adsorption mechanism studies by FTIR and XPS found that hard-soft acid-base principle, surface complexation and ion-exchange were the main interactions between metal ions and surface functional groups. The adsorption selectivity of SH-MCM-41 obeys the hard-soft acid-base principle. It was suitable for separation of hard and soft metal ions such as Ag+ and Cu 2+. Stability constants could be as the guideline for predicting the adsorption of NH2-MCM-41 which was able to separate metals with different complexing ability. Furthermore, ion-exchange mechanism governs the adsorption of COONa-MCM-41 and it was capable of separating cationic metals from metallic oxyanions. Factors such as functional group loading, amount of adsorbent, solution pH and metal composition of solution could affect both adsorption capacity and selectivity of the adsorbents depending on the adsorption mechanisms. By identifying the adsorption mechanism, the selective adsorbents was designed for precious metal recovery and toxic metal separation. It was found that both SH-MCM-41 and NH2-MCM-41 were able to remove gold in the presence of other metals and these adsorbents were efficient to adsorb trace amount of gold from the solution. The regenerable NH2-MCM-41 could be re-used for five times without loss of performance. On the other hand, NH2-MCM-41 was used to separate toxic cadmium ions from Ni-Cd solution. It was found that the addition of EDTA improved the adsorption selectivity. NH2-MCM-41 only remove Cd2+ at pH5.0 while the adsorbent removed Ni2+ at pH3.0. This introduces an opportunity to recover both metal ions from spent Ni-Cd battery wastes.

  4. Single-metal-ion-based molecular building blocks (MBBs) approach to the design and synthesis of metal organic assemblies

    NASA Astrophysics Data System (ADS)

    Brant, Jacilynn A.; Liu, Yunling; Sava, Dorina F.; Beauchamp, Derek; Eddaoudi, Mohamed

    2006-08-01

    The single-metal-ion-based molecular building blocks (MBBs) approach for the construction of metal-organic assemblies, in which hetero-coordinated single metal ions are rendered rigid and directional via nitrogen-oxygen chelation with judiciously selected ligands, has been implemented. Single-metal-ion-based MBBs of the general formula MN x(CO 2) y constitute the building units of metal-organic frameworks (MOFs) and metal-organic polyhedra (MOPs) presented herein. The octahedral MBB, MN 2(CO 2) 4, can occur as two structural isomers depending on the positioning of nitrogen atoms. The MN 2(CO 2) 4 MBBs contain two rings of heterochelation, and depending on the position of the oxygen atoms involved in heterochelation it is possible to generate three different building units (BUs) from the cis-MN 2(CO 2) 4 MBB and two BUs from the trans-MN 2(CO 2) 4 MBB. Assembly of the different BUs derived from the cis-MN 2(CO 2) 4 MBB, through a bifunctional ligand such as 2,5-pyridinedicarboxylic acid, permits the construction of diverse assemblies, such as a metal-organic 2D Kagomé lattice, a discrete octahedron, and a 3D diamondoid-like network. The fac-MN 3(CO 2) 3 MBB mediates a BU with the appropriate geometry to facilitate the formation of a metal-organic cube, and the BU resulting from the mer-MN 3(CO 2) 3 MBB is T-shaped. Tetrahedral building units (TBUs) can be derived either from MN 4(CO 2) 2 or MN 4(CO 2) 4 MBBs, from which zeolite-like MOFs have been constructed. Foremost, rationalization and systemization of such findings offer great potential toward the pursuit of the logical synthesis of functional metal-organic assemblies.

  5. An Update on the Lithium-Ion Cell Low-Earth-Orbit Verification Test Program

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Manzo, Michelle A.; Miller, Thomas B.; McKissock, Barbara I.; Bennett, William

    2007-01-01

    A Lithium-Ion Cell Low-Earth-Orbit Verification Test Program is being conducted by NASA Glenn Research Center to assess the performance of lithium-ion (Li-ion) cells over a wide range of low-Earth-orbit (LEO) conditions. The data generated will be used to build an empirical model for Li-ion batteries. The goal of the modeling will be to develop a tool to predict the performance and cycle life of Li-ion batteries operating at a specified set of mission conditions. Using this tool, mission planners will be able to design operation points of the battery system while factoring in mission requirements and the expected life and performance of the batteries. Test conditions for the program were selected via a statistical design of experiments to span a range of feasible operational conditions for LEO aerospace applications. The variables under evaluation are temperature, depth-of-discharge (DOD), and end-of-charge voltage (EOCV). The baseline matrix was formed by generating combinations from a set of three values for each variable. Temperature values are 10 C, 20 C and 30 C. Depth-of-discharge values are 20%, 30% and 40%. EOCV values are 3.85 V, 3.95 V, and 4.05 V. Test conditions for individual cells may vary slightly from the baseline test matrix depending upon the cell manufacturer s recommended operating conditions. Cells from each vendor are being evaluated at each of ten sets of test conditions. Cells from four cell manufacturers are undergoing life cycle tests. Life cycling on the first sets of cells began in September 2004. These cells consist of Saft 40 ampere-hour (Ah) cells and Lith ion 30 Ah cells. These cells have achieved over 10,000 cycles each, equivalent to about 20 months in LEO. In the past year, the test program has expanded to include the evaluation of Mine Safety Appliances (MSA) 50 Ah cells and ABSL battery modules. The MSA cells will begin life cycling in October 2006. The ABSL battery modules consist of commercial Sony hard carbon 18650 lithium-ion cells configured in series and parallel combinations to create nominal 14.4 volt, 3 Ah packs (4s-2p). These modules have accumulated approximately 3000 cycles. Results on the performance of the cells and modules will be presented in this paper. The life prediction and performance model for Li-ion cells in LEO will be built by analyzing the data statistically and performing regression analysis. Cells are being cycled to failure so that differences in performance trends that occur at different stages in the life of the cell can be observed and accurately modeled. Cell testing is being performed at the Naval Surface Warfare Center in Crane, IN.

  6. Adherence of ion beam sputter deposited metal films on H-13 steel

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.

    1980-01-01

    An electron bombardment argon ion source was used to sputter deposit 17 different metal and metal oxide films ranging in thickness from 1 to 8 micrometers on H-13 steel substrates. The film adherence to the substrate surface was measured using a tensile test apparatus. Comparisons in bond strength were made between ion beam, ion plating, and RF deposited films. A protective coating to prevent heat checking in H-13 steel dies used for aluminum die casting was studied. The results of exposing the coated substrates to temperatures up to 700 degrees are presented.

  7. Ion Temperatures in Earth's Inner Magnetosphere: Ring Current Dynamics, Transient Effects, and Data-Model Comparisons

    NASA Astrophysics Data System (ADS)

    Elfritz, Justin G.

    Earth's magnetosphere is an inherently complex, strongly nonlinear system with intrinsic coupling between internal and external drivers. In general, magnetospheric systems can be understood as a balance between multiple regions which all exhibit unique plasma properties. The feedback processes between each region depend on geomagnetic activity levels and the preceding states of the solar wind and the respective magnetospheric regions. Of particular interest is understanding how ion temperatures evolve during geomagnetically active periods, and also understanding the space weather impacts of hot ion populations injected during such periods. Dynamic, spatiotemporally resolved ion temperature boundary conditions have been implemented into the Comprehensive Ring Current Model (CRCM); the temperatures are based on 2-D equatorial maps derived from remotely imaged energetic neutral atom (ENA) measurements. The high-speed-stream-driven event on 22 July 2009 and the coronal mass ejection-driven event on 30-31 October 2013 are simulated and compared against identical simulations using a statistically derived boundary condition model. This new method for establishing boundary conditions allows users to include event-specific observations associated with a dynamic plasma sheet. It is found that spatial and energy distributions in the storm-time ring current exhibit sensitive dependence on boundary conditions during these events. The coupling of boundary conditions to the time history of the convection electric field strength is found to play an important role in throttling the influence of the boundary plasma on the inner magnetosphere. Storm-time dusk-dawn asymmetries consistent with observational data are reproduced well when CRCM is provided with the event-specific boundary condition model. The dependence of average, global magnetospheric ion temperatures derived from ENA maps is also investigated as a function of various combinations of solar wind parameters, IMF parameters, and geomagnetic indices. Covering a 31-month interval of time near solar maximum, the parametric study reveals average stormtime features consistent with various in situ observations, ionospheric observations, and ground-based measurements.

  8. Synthesis of Metal Oxide Particles Using Reaction Route from Rare-Earth Metal-EDTA Complexes

    NASA Astrophysics Data System (ADS)

    Komatsu, Keiji; Tsuchiya, Takaaki; Hasebe, Yasuhiro; Sekiya, Tetsuo; Toyama, Ayumu; Nakamura, Atsushi; Akasaka, Hiroki; Saitoh, Hidetoshi

    2014-06-01

    Highly dense, spherical yttria (Y2O3) and erbia (Er2O3) particles were synthesized from their corresponding metal-ethylenediaminetetraacetic (EDTA) complexes. The EDTA·Y·H and EDTA·Er·H complexes were prepared in powdered form. These complexes were used as the staring materials for synthesis of the Y2O3 and Er2O3 particles. The particles were synthesized using an H2-O2 flame produced with a commercial flame spray apparatus. Crystalline structure, surface and cross-sectional morphologies, and elemental distribution of the synthesized particles were investigated. It was confirmed that the crystalline phases of the Y2O3 and Er2O3 particles were homogeneous. In addition, the elemental distribution of the particles was uniform. These results indicate that dense, spherical particles of Y2O3 and Er2O3 have been synthesized with EDTA·Y·H and EDTA·Er·H complexes, respectively.

  9. Percolation of gallium dominates the electrical resistance of focused ion beam deposited metals

    SciTech Connect

    Faraby, H.; DiBattista, M.; Bandaru, P. R.

    2014-04-28

    Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

  10. Effects of CoCr metal wear debris generated from metal-on-metal hip implants and Co ions on human monocyte-like U937 cells.

    PubMed

    Posada, Olga M; Tate, Rothwelle J; Grant, M Helen

    2015-03-01

    Hip resurfacing with cobalt-chromium (CoCr) alloy was developed as a surgical alternative to total hip replacement. However, the biological effects of nanoparticles generated by wear at the metal-on-metal articulating surfaces has limited the success of such implants. The aim of this study was to investigate the effects of the combined exposure to CoCr nanoparticles and cobalt ions released from a resurfacing implant on monocytes (U937 cells) and whether these resulted in morphology changes, proliferation alterations, toxicity and cytokine release. The interaction between prior exposure to Co ions and the cellular response to nanoparticulate debris was determined to simulate the situation in patients with metal-on-metal implants receiving a second implant. Effects on U937 cells were mainly seen after 120h of treatment. Prior exposure to Co ions increased the toxic effects induced by the debris, and by Co ions themselves, suggesting the potential for interaction in vivo. Increased TNF-? secretion by resting cells exposed to nanoparticles could contribute to osteolysis processes in vivo, while increased IFN-? production by activated cells could represent cellular protection against tissue damage. Data suggest that interactions between Co ions and CoCr nanoparticles would occur in vivo, and could threaten the survival of a CoCr metal implant. PMID:25433333

  11. The Gellyfish: an in-situ equilibrium-based sampler for determining multiple free metal ion concentrations in marine ecosystems

    EPA Science Inventory

    Free metal ions are usually the most bioavailable and toxic metal species to aquatic organisms, but they are difficult to measure because of their extremely low concentrations in the marine environment. Many of the current methods for determining free metal ions are complicated a...

  12. Predicting relative toxicity and interactions of divalent metal ions: Microtox{reg_sign} bioluminescence assay

    SciTech Connect

    Newman, M.C.; McCloskey, J.T.

    1996-03-01

    Both relative toxicity and interactions between paired metal ions were predicted with least-squares linear regression and various ion characteristics. Microtox{reg_sign} 15 min EC50s (expressed as free ion) for Ca(II), Cd(II), Cu(II), Hg(II), Mg(II), Mn(II), Ni(II), Pb(II), and Zn(II) were most effectively modeled with the constant for the first hydrolysis (K{sub H} for M{sup n+} + H{sub 2}O {yields} MOH{sup a{minus}1} + H{sup +}) although other ion characteristics were also significant in regression models. The {vert_bar}log K{sub H}{vert_bar} is correlated with metal ion affinity to intermediate ligands such as many biochemical functional groups with O donor atoms. Further, ordination of metals according to ion characteristics, e.g., {vert_bar}log K{sub H}{vert_bar} facilitated prediction of paired metal interactions. Pairing metals with strong tendencies to complex with intermediate or soft ligands such as those with O or S donor atoms resulted in strong interactions.

  13. Tidal Downsizing model - III. Planets from sub-Earths to brown dwarfs: structure and metallicity preferences

    NASA Astrophysics Data System (ADS)

    Nayakshin, Sergei; Fletcher, Mark

    2015-09-01

    We present population synthesis calculations of the Tidal Downsizing (TD) hypothesis for planet formation. Our models address the following observations: (i) most abundant planets being super-Earths; (ii) cores more massive than ˜5-15 M? are enveloped by massive atmospheres; (iii) the frequency of occurrence of close-in gas-giant planets correlates strongly with metallicity of the host star; (iv) no such correlation is found for sub-Neptune planets; (v) presence of massive cores in giant planets; (vi) gas-giant planets are overabundant in metals compared to their host stars; (vii) this overabundance decreases with planet's mass; (viii) a deep valley in the planet mass function between masses of ˜10-20 M? and ˜100 M?. A number of observational predictions distinguish the model from Core Accretion: (a) composition of the massive cores is always dominated by rocks not ices; (b) the core mass function is smooth with no minimum at ˜3 M? and has no ice-dominated cores; (c) gas giants beyond 10 au are insensitive to the host-star metallicity; (d) objects more massive than ˜10 MJ do not correlate or even anticorrelate with metallicity. The latter prediction is consistent with observations of low-mass stellar companions. TD can also explain formation of planets in close binary systems. TD model is a viable alternative to the Core Accretion scenario in explaining many features of the observed population of exoplanets.

  14. Evaluation of dynamic ion exchange for the isolation of metal ions for characterization by mass and. cap alpha. spectrometry

    SciTech Connect

    Cassidy, R.M.; Miller, F.C.; Knight, C.H.; Roddick, J.C.; Sullivan, R.W.

    1986-06-01

    A /sup 140/La tracer has been used to identify the sources of cross-contamination when conventional high-performance liquid chromatography was used to collect metal ion fractions for subsequent analysis by ..cap alpha.. spectrometry or mass spectrometry. Major sources of memory effects identified were normal band broadening, sorption onto metal surfaces, and retention within sample valves; secondary sorption effects within the column and isotopic exchange with sorbed metal ions were not important sources of memory effects. On the basis of these results a recommended procedure was developed that gives cross-contamination levels of less than or equal to 0.006%. Sample preparation techniques for the ..cap alpha.. spectrometric and mass spectrometric analyses of the collected fractions are discussed, and some examples are given of applications to analytical problems in geochemistry and the nuclear industry. Good sample recoveries were obtained for the sample range studied (0.1-500 ng).

  15. Highly ordered three-dimensional macroporous carbon spheres for determination of heavy metal ions

    SciTech Connect

    Zhang, Yuxiao; Zhang, Jianming; Liu, Yang; Huang, Hui; Kang, Zhenhui

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Highly ordered three dimensional macroporous carbon spheres (MPCSs) were prepared. Black-Right-Pointing-Pointer MPCS was covalently modified by cysteine (MPCS-CO-Cys). Black-Right-Pointing-Pointer MPCS-CO-Cys was first time used in electrochemical detection of heavy metal ions. Black-Right-Pointing-Pointer Heavy metal ions such as Pb{sup 2+} and Cd{sup 2+} can be simultaneously determined. -- Abstract: An effective voltammetric method for detection of trace heavy metal ions using chemically modified highly ordered three dimensional macroporous carbon spheres electrode surfaces is described. The highly ordered three dimensional macroporous carbon spheres were prepared by carbonization of glucose in silica crystal bead template, followed by removal of the template. The highly ordered three dimensional macroporous carbon spheres were covalently modified by cysteine, an amino acid with high affinities towards some heavy metals. The materials were characterized by physical adsorption of nitrogen, scanning electron microscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. High sensitivity was exhibited when this material was used in electrochemical detection (square wave anodic stripping voltammetry) of heavy metal ions due to the porous structure. And the potential application for simultaneous detection of heavy metal ions was also investigated.

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

    SciTech Connect

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

    1989-01-01

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

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

    PubMed

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

    2013-01-01

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

  18. Effect of metal ions on melanin--local anaesthetic drug complexes.

    PubMed

    Buszman, Ewa; Betlej, Bozena; Wrze?niok, Dorota; Radwa?ska-Wala, Bozena

    2003-01-01

    The affinity of melanin biopolymers for metal ions, drugs and other organic compounds is an important factor in the etiology of toxic retinopathy, hiperpigmentation, otic lesions and irreversible extrapyramidal disorders. The aim of the presented work was to examine the interaction of local anaesthetic drugs used in ophthalmology with model DOPA-melanin in the presence of metal ions. It has been demonstrated that the analyzed drugs form complexes with melanin biopolymer. Based on the .values of association constants,, the following order of drugs affinity to melanin was found: tetracaine > procaine > bupivacaine > lidocaine. It has also been shown that Cu(2+) and Zn(2+) ions administered to DOPA-melanin before complexing with drugs decrease the total amount of local anaesthetics bound to melanin. The blocking of some active centers in melanin molecules by metal ions, which potentially exist in living systems, may change the clinical therapeutic efficiency of the analyzed local anaesthetic drugs. PMID:18365047

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

    PubMed Central

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

    2013-01-01

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

  20. Surface phenomena in liquid metal alloys with application to development of a liquid metal ion source of B and As

    SciTech Connect

    Bozack, M.J.

    1985-01-01

    A liquid metal ion (LMI) source is a low volatility liquid metal film which flows to the apex of a solid needle support structure. Subsequent application of a high electric field deforms the liquid and results in ion emission. Considerable interest has been shown in development of LMI sources capable of producing a variety of technologically important ions. For implantation of silicon, for example, B is the preferred p-type dopant, while As and P are the preferred n-type dopants. It has been difficult to construct long-lived ion sources based upon these species because B possesses a high melting point and reacts strongly with most refractory metal supports, while As and P have high vapor pressures. To overcome these difficulties, the material and thermochemical properties of liquid metal alloy surfaces were studied. A number of successful contact systems were identified for B, while the development of a LMI source of As was completely solved. To lower the chemical reactivity of B alloys, it was necessary to utilize nonmetallic support structures. In these cases wettability of B based alloys is governed by surface segregation of low-level, low-surface tension impurities within the alloys that inhibit reaction between the alloy and substrate. Coating the substrate with a material having a high affinity to carbon (e.g., B, or Si) acts to tie up the segregated material and promote wetting.