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1

METHOD OF SEPARATING RARE EARTH METAL IONS  

Microsoft Academic Search

A method for separating rare earth metal ions by cation exchange is ; given. The method comprises sorbing the metal ions on the hydrogen form of a ; sulfonic acid type cation exchange resin, eluting the metals from the resin with ; a 0.01 to 0.1 M aqueous solution of an alkali salt of diethylenetriamine ; pentaacetic acid, and collecting

1962-01-01

2

Epoxy Polymers Containing Coordinated Rare-Earth Metal Ions  

Microsoft Academic Search

Solid, optically transparent polymers with a high (up to 25 wt %) content of coordination-bound rare-earth elements were prepared by curing glycidyl esters of phosphorus acids with rare-earth metal salts.

L. M. Amirova; V. P. Fomin; R. R. Amirov

2003-01-01

3

Significant thermal conductivity enhancement in graphene oxide papers modified with alkaline earth metal ions  

NASA Astrophysics Data System (ADS)

The thermal conductivities of graphene oxide paper (GOP) and the alkaline earth metal ions (Mg2+, Ca2+) modified analogues, prepared by a facile vacuum filtration method, were measured by a laser flash method. The thermal conductivities of GOP, Mg-modified GOP, and Ca-modified GOP are 3.91 W/(m × K), 32.05 W/(m × K), and 61.38 W/(m × K), respectively, which indicate the modification of GOP with metal ions has resulted in significant enhancement in thermal conduction properties compared with unmodified GOP. The crosslink between graphene oxide sheet and metal ions, the neat stacking of graphene oxide sheets in modified GOP, together with the intercalation of metal ions into the gallery spaces between the graphene oxide sheet basal planes, result in a decrease of thermal resistance of the boundary and an increase of contact surface, thus increases the thermal conductivity of modified graphene oxide paper.

Yu, Wei; Xie, Huaqing; Li, Fengxian; Zhao, Junchang; Zhang, Zhenhai

2013-09-01

4

Rare Earth Metal Ions for DNA Hydrolyses and Their Use to Artificial Nuclease  

Microsoft Academic Search

Phosphodiester linkages in linear DNAs are efficiently hydrolyzed by rare earth metal salts. The activities of CeCl3 and Ce(NH4)2(NO3)6 are especially large. Artificial hydrolytic nuclease for highly selective scission of DNA has been prepared by the attachment of Ce(IV) ion to a DNA oligomer as a sequence recognizing moiety.

Makoto Komiyama; Naoya Takeda; Tetsuro Shiiba; Yota Takahashi; Yoichi Matsumoto; Morio Yashiro

1994-01-01

5

Heavy metal oxide glasses doped by rare earth ions for optoelectronics  

Microsoft Academic Search

Heavy metal oxide glasses in the system TeO2-PbO-WO3 doped by selected rare earth ions have been presented. The method of their preparation and physical properties were determined. Infrared luminescence of Er3+ and Tm3+ ions embedded in TeO2-PbO-WO3 glass hosts is reported for room and helium liquid temperatures. The substantial influence of energy transfer processes between the glass host and Er3+

Dominik Dorosz; Jan Wasylak

2005-01-01

6

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

SciTech Connect

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

Legin, A.; Kirsanov, D.; Rudnitskaya, A. [St. Petersburg University, Chemistry Department, Laboratory of Chemical Sensors, Universitetskaya nab. 7/9, St. Petersburg, 199034 (Russian Federation); Babain, V. [Khlopin Radium Institute, 28, 2nd Murinsky av., St. Petersburg, 194021 (Russian Federation); Rovny, S.; Logunov, M. [PA Mayak, Ozyorsk (Russian Federation)

2007-07-01

7

Normal-mode coupling of rare-earth-metal ions in a crystal to a macroscopic optical cavity mode  

SciTech Connect

We demonstrated coupling of rare-earth-metal ions in a crystal to a macroscopic cavity mode by observing optical bistability and normal-mode peaks due to sweeping-laser-induced population redistribution of the ions. The experimentally evaluated coupling constant between the individual ions and the single cavity mode is 15 kHz, which is comparable with or larger than the dissipation of the ions and will exceed the cavity dissipation with a narrowing of the mode waist of the cavity to the wavelength. The results advance the application of a coupled system of rare-earth-metal ions in a crystal and an optical cavity for quantum information processing.

Ichimura, Kouichi; Goto, Hayato [Frontier Research Laboratory, Corporate Research and Development Center, Toshiba Corporation, 1 Komukai-Toshiba-cho, Saiwai-ku, Kawasaki, 212-8582 (Japan)

2006-09-15

8

Unambiguously identifying spin states of transition-metal ions in the Earth (Invited)  

NASA Astrophysics Data System (ADS)

The spin state of a transition-metal ion in crystalline solids, defined by the number of unpaired electrons in the ion’s incomplete 3d shell, may vary with many factors, such as temperature, pressure, strain, and the local atomic configuration, to name a few. Such a phenomenon, known as spin-state crossover, plays a crucial role in spintronic materials. Recently, the pressure-induced spin-state crossover in iron-bearing minerals has been recognized to affect the minerals’ structural and elastic properties. However, the detailed mechanism of such crossover in iron-bearing magnesium silicate perovskite, the most abundant mineral in the Earth, remains unclear. A significant part of this confusion arises from the difficulty in reliably extracting the spin state from experiments. For the same reason, the thermally-induced spin-state crossover in lanthanum cobaltite (LaCoO3) has been controversial for more than four decades. In this talk, I will discuss how first-principle calculations can help clarifying these long-standing controversies. In addition to the total energy, equation of state, and elastic properties of each spin state, first-principle calculations also predict the electric field gradient (EFG) at the nucleus of each transition-metal ion. Our calculations showed that the nuclear EFG, a quantity that can be measured via Mössbauer or nuclear magnetic resonance (NMR) spectroscopy, depends primarily on the spin state, irrespective of the concentration or configuration of transition-metal ions. Such robustness makes EFG a unique fingerprint to identify the spin state. The combination of first-principle calculations and Mössbauer/NMR spectroscopy can therefore be a reliable and efficient approach in tackling spin-state crossover problems in the Earth. This work was primarily supported by the MRSEC Program of NSF under Awards Number DMR-0212302 and DMR-0819885, and partially supported by NSF under ATM-0428774 (V-Lab), EAR-1019853, and EAR-0810272. The computations were performed mainly at the Minnesota Supercomputing Institute (MSI).

Hsu, H.

2010-12-01

9

Luminescence properties of rare earth and transition metal ions doped potassium lead borophosphate glass  

NASA Astrophysics Data System (ADS)

A series of potassium lead borophosphate glass doped with rare earth and transition metal ions were fabricated using melt-quenching method without annealing process. With the composition of glass 0.15K2O-0.15PbO-0.35B2O3-0.5P2O5 as host doped with 0.01 mole % of neodymium oxide, iron oxide, yttrium oxide, and titanium oxide as activator and different composition were used to investigate the luminescence effect by using Photoluminescence Spectroscopy and UV-Vis (Ultraviolet-Visible) spectrophotometer. By exciting the samples at different wavelength (200-900 nm), the excitation and emission profile were obtained and analyzed to study the energy transfer process. By referring to the spectra obtained, selected samples were also codoped among each other to obtain desired luminescence properties. UV-Visible spectroscopy results revealed the absorption and transmission wavelength of samples for targeted application as a selected band filter. Physical properties such as chemical stability and color of the samples were also recorded to correlate with PL and UV-Vis result. Certain rare earth activated samples displayed slight coloring under the visible wavelength especially Nd2+ ions doped samples displayed slight purplish.

Leong, P. M.; Eeu, T. Y.; Leow, T. Q.; Hussin, R.; Ibrahim, Z.

2013-05-01

10

Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal  

SciTech Connect

In optically controlled quantum computers it may be favorable to address different qubits using light with different frequencies, since the optical diffraction does not then limit the distance between qubits. Using qubits that are close to each other enables qubit-qubit interactions and gate operations that are strong and fast in comparison to qubit-environment interactions and decoherence rates. However, as qubits are addressed in frequency space, great care has to be taken when designing the laser pulses, so that they perform the desired operation on one qubit, without affecting other qubits. Complex hyperbolic secant pulses have theoretically been shown to be excellent for such frequency-addressed quantum computing [I. Roos and K. Molmer, Phys. Rev. A 69, 022321 (2004)] - e.g., for use in quantum computers based on optical interactions in rare-earth-metal-ion-doped crystals. The optical transition lines of the rare-earth-metal-ions are inhomogeneously broadened and therefore the frequency of the excitation pulses can be used to selectively address qubit ions that are spatially separated by a distance much less than a wavelength. Here, frequency-selective transfer of qubit ions between qubit states using complex hyperbolic secant pulses is experimentally demonstrated. Transfer efficiencies better than 90% were obtained. Using the complex hyperbolic secant pulses it was also possible to create two groups of ions, absorbing at specific frequencies, where 85% of the ions at one of the frequencies was shifted out of resonance with the field when ions in the other frequency group were excited. This procedure of selecting interacting ions, called qubit distillation, was carried out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals. The techniques for frequency-selective state-to-state transfer developed here may be also useful also for other quantum optics and quantum information experiments in these long-coherence-time solid-state systems.

Rippe, Lars; Nilsson, Mattias; Kroell, Stefan; Klieber, Robert; Suter, Dieter [Department of Physics, Lund Institute of Technology, P.O. Box 118, SE-22100 Lund (Sweden); Fachbereich Physik, Universitaet Dortmund, DE-44221 Dortmund (Germany)

2005-06-15

11

Spin-orbit thermal entanglement in a rare-earth-metal ion: Susceptibility witness  

NASA Astrophysics Data System (ADS)

In the present work, we explore the thermal entanglement between spin and orbital angular momentum in a rare-earth ion. A witness, based on the magnetic susceptibility and capable of revealing entanglement between these two angular momenta of different nature, is introduced. We found entanglement temperatures of 322 K for promethium and 715 K for samarium. These high temperatures make interesting the use of rare-earth in applications of quantum-information processes at room temperature.

Duarte, O. S.; Castro, C. S.; Reis, M. S.

2013-07-01

12

Rare-earth neutral metal injection into an electron beam ion trap plasmaa)  

NASA Astrophysics Data System (ADS)

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 ?10-7 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.

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

2014-11-01

13

A fast assay of water hardness ions based on alkaline earth metal induced coacervation (HALC)  

Microsoft Academic Search

In this work, a rapid assay of water hardness is presented based on the formation of a coacervate phase made up of multilamellar vesicles and close bilayers produced upon the reaction of alkaline earth metals with a carboxylate anionic surfactant in the presence of a co-surfactant (methanol). The procedure exploits the light scattering abilities of the coacervate phase which can

George Z. Tsogas; Dimosthenis L. Giokas; Athanasios G. Vlessidis

2010-01-01

14

Unambiguously identifying spin states of transition-metal ions in the Earth (Invited)  

Microsoft Academic Search

The spin state of a transition-metal ion in crystalline solids, defined by the number of unpaired electrons in the ion's incomplete 3d shell, may vary with many factors, such as temperature, pressure, strain, and the local atomic configuration, to name a few. Such a phenomenon, known as spin-state crossover, plays a crucial role in spintronic materials. Recently, the pressure-induced spin-state

H. Hsu

2010-01-01

15

Quantitative separations of La(III) from alkaline earth metal ions using a new, poorly crystalline inorganic ion exchanger: niobium molybdate  

SciTech Connect

Preparation of niobium molybdate for use as an ion-exchange material is described. The material has a Nb/Mo mole ratio of 0.9346 and has a high thermal stability. Results of ir, x-ray, thermogravimetric and differential scanning calorimetric analyses of the niobium molybdate are reported. The niobium molybdate is useful as an ion exchanger up to 300/sup 0/C. Determination of the distribution coefficients of 14 metal ions in demineralized water and 10/sup -2/M HNO/sub 3/ on the molybdate indicated high absorption toward Cu(II), Bi(III), La(III), Pr(III), and Th(IV); but low absorption for alkaline earth metal ions, Zn(II), Cd(II), Mn(II), and Al(III). (BLM)

Qureshi, M.; Gupta, A.P.; Thakur, J.S.; Singh, V.P.

1980-01-01

16

A fast assay of water hardness ions based on alkaline earth metal induced coacervation (HALC).  

PubMed

In this work, a rapid assay of water hardness is presented based on the formation of a coacervate phase made up of multilamellar vesicles and close bilayers produced upon the reaction of alkaline earth metals with a carboxylate anionic surfactant in the presence of a co-surfactant (methanol). The procedure exploits the light scattering abilities of the coacervate phase which can be logarithmically linked to total hardness as CaCO(3) equivalents via spectrophotometric detection at 350 nm. The method, abbreviated as HALC, stemming from hardness by alkaline earth metal coacervation, is straightforwardly applicable overcoming the requirement for regulation of the experimental parameters involved in the determination procedure. In total, 28 water samples with various matrix compositions and hardness contents were analyzed with satisfactory accuracy as evidenced by comparison of the results with EDTA complexometric titration. The method is free from interferences from environmentally significant metal cations and inorganic anions affording detection limits as low as 13.5 mg L(-1) CaCO(3) with the aid of a correction factor, which is determined by the non-linear absorbance properties of the solution mixture, and satisfactory reproducibility (RSD=4.21-8.08%). PMID:20152451

Tsogas, George Z; Giokas, Dimosthenis L; Vlessidis, Athanasios G

2010-03-15

17

Method for separating rare earth metal  

SciTech Connect

Rare earth metals are adsorbed on an ion exchanger fiber comprising an ion exchanger having a strong cation exchange group and a weak cation exchange group, and the adsorbed metals are fractionally eluted with an aqueous solution of a chelating agent, whereby the respective rare earth metals can be separated at high efficiency in a short time. According to this method, elution can be accomplished at an elution rate of 5.0 or above in terms of space velocity.

Asami, T.; Ichijo, H.; Ogawa, S.; Suehiro, T.; Suzuki, M.; Uzumaki, M.; Yamauchi, A.

1985-04-30

18

Rare earth metal borocarbides  

Microsoft Academic Search

A variety of structural types of solid-state rare earth metal borocarbide materials containing infinite two-dimensional layers, infinite one-dimensional chains, or finite groups of boron and carbon are reviewed. Although the solid-state language of Zintl–Klemm concept, band structures, and density of states is necessary to rationalize this kind of compound, they are governed by the laws that guide most molecular and

Josef Bauer; Jean-François Halet; Jean-Yves Saillard

1998-01-01

19

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

SciTech Connect

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.

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

1995-01-01

20

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

21

Spectroscopic, thermal and antitumor investigations of sulfasalazine drug in situ complexation with alkaline earth metal ions  

NASA Astrophysics Data System (ADS)

The complexes of sulfasalazine (H 3Suz) with some of alkaline metals Mg(II), Ca(II), Sr(II) and Ba(II) have been investigated. Sulfasalazine complexes were synthesized and characterized by spectroscopic tools; infrared spectra, electronic and mass spectra. The IR spectra of the prepared complexes were suggested that the H 3Suz behaves as a bi-dentate ligand through the carboxylic and phenolic groups. The molar conductance measurements gave an idea about the non-electrolytic behavior of the H 3Suz complexes. The thermal decomposition processes for metal(II) complexes of H 3Suz viz: [M(HSuz)(H 2O) 4] (where M = Mg(II), Ca(II), Sr(II) or Ba(II)) have been accomplished on the basis of TG/DTG and DTA studies, and the formula conforms to the stoichiometry of the complexes based on elemental analysis. The kinetic analyses of the thermal decomposition were studied using the Coats-Redfern and Horowitz-Metzger equations. The antitumor and antimicrobial activities of the H 3Suz and their alkaline metal(II) complexes were evaluated.

Refat, Moamen S.; Mohamed, Soha F.

2011-11-01

22

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

PubMed

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

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

2013-02-01

23

EXTRACTIVE PROPERTIES TOWARDS RARE-EARTH METAL IONS OF CALIX[ 4] ARENES SUBSTITUTED AT THE NARROW RIM BY PHOSPHORYL AND AMIDE GROUPS  

Microsoft Academic Search

The extractive properties of the cone and partial-cone isomers of 5,11,17,23-tetra-?ert-butyl-25,27-bis( diethylcarbamoylmethoxy)-26,28-bisi( diphenylphospninoylmethoxy) calyx[ 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

M. R. Yaftian; M. Burgard; C. Wieseir; C. B. Dieleman; D. Matt

1998-01-01

24

Structural diversity in binuclear complexes of alkaline earth metal ions with 4,6-diacetylresorcinol  

NASA Astrophysics Data System (ADS)

A new series of binuclear and mixed-ligand complexes with the general formula: [M 2(LO)yClz]; where M = Mg(II), Ca(II), Sr(II) and Ba(II); H2L = 4,6-diacetylresorcinol, the secondary ligand L' = acetylacetone (acac), 8-hydroxyquinoline (8-HQ) or 2,2'-bipyridyl (Bipy), n = 0-2, m = 1, 2, x = 0, 1, 2, 4, y = 0, 2, 4, 5 and z = 0-2; have been synthesized. They have been characterized by the analytical and spectral methods (IR, 1H NMR and mass) as well as TGA and molar conductivity measurements. The spectroscopic and conductance data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the basicity of the secondary ligand, through the two phenolic and two carbonyl groups. Binuclear octahedral geometry has been assigned to all of the prepared complexes in various molar ratios 2:2; 2:2:2; 1:2:1 and 1:2:4 (L:M:L'). Molecular orbital calculations were performed for the ligands and their complexes using Hyperchem 7.52 program on the bases of PM3 level and the results were correlated with the experimental data. The ligand and some of its alkaline metal(II) complexes showed antibacterial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

2012-11-01

25

Rare-earth metal-ion separation using a supported liquid membrane mediated by a narrow rim phosphorylated calix[4]arene  

Microsoft Academic Search

The transport of rare-earth metal ions through a supported liquid membrane mediated by 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(diphenylphosphinoylmethoxy)calix[4]arene (1) (cone conformation) in o-nitrophenyl hexyl ether (NPHE) has been investigated. The effect of the initial metal concentration, salting-out agent concentration in the feed phase and temperature as well as the carrier concentration on the flux was studied. The separation ability of ligand 1 was tested

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

1998-01-01

26

Strong-coupling cavity QED using rare-earth-metal-ion dopants in monolithic resonators: What you can do with a weak oscillator  

SciTech Connect

We investigate the possibility of achieving the strong coupling regime of cavity quantum electrodynamics using rare-earth-metal-ions as impurities in monolithic optical resonators. We conclude that due to the weak oscillator strengths of the rare-earth-metals, it may be possible but difficult to reach the regime where the single photon Rabi frequency is large compared to both the cavity and atom decay rates. However, reaching the regime where the saturation photon and atom numbers are less than one should be much more achievable. We show that in this 'bad cavity' regime, transfer of quantum states and an optical phase shift conditional on the state of the atom is still possible and suggest a method for coherent detection of single dopants.

McAuslan, D. L.; Longdell, J. J.; Sellars, M. J. [Jack Dodd Centre for Photonics and Ultra-Cold Atoms, Department of Physics, University of Otago, Dunedin (New Zealand); Laser Physics Centre, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

2009-12-15

27

Effect of sodium ions on the extraction of rare earth metals by liquid surfactant membranes containing a calix[4]arene carboxyl derivative  

Microsoft Academic Search

A novel host compound calixarene has been applied as a mobile carrier for the separation and concentration of rare earth metals by liquid surfactant membranes (LSMs). Using the novel carrier, extraction of rare earth metals (Ho, Er and Y) by LSMs was systematically studied in a stirred cell. Extraction behavior of rare earth metals by the carboxyl derivative of calix[4]arene

Takahiko Kakoi; Tatsuya Oshima; Takayuki Nishiyori; Fukiko Kubota; Masahiro Goto; Seiji Shinkai; Fumiyuki Nakashio

1998-01-01

28

Intermultiplet transitions in rare-earth metals  

SciTech Connect

We report here on direct observations of intermultiplet (IM) transitions in the rare-earth metals, Pr, Nd and Tb, made using the chopper spectrometers at the Intense Pulsed Neutron Source of Argonne National Laboratory. Despite hydrogen contamination of the polycrystalline samples, we have observed inelastic peaks at small Q arising from IM transitions in Pr (approx.260 MeV), Nd (approx.242 MeV) and Tb (approx.256 MeV) although the latter has not yet been observed unambiguously. Future work will investigate the energy level structure and dynamical properties of rare-earth ions in stoichiometric metallic systems. 5 refs., 3 figs.

Stirling, W.G.; McEwen, K.A.; Loong, C.K.

1985-01-01

29

Thermophysical properties of liquid rare earth metals  

NASA Astrophysics Data System (ADS)

The thermodynamical properties like long wavelength limit S(0), iso-thermal compressibility (?T), thermal expansion coefficient (?V), thermal pressure coefficient (?V), specific heat at constant volume (CV) and specific heat at constant pressure (CP) are calculated for liquid rare earth metals. Our newly constructed parameter free model potential is used to describe the electron ion interaction due to Sarkar et al (S) local field correction function. Lastly, we conclude that our newly constructed model potential is capable to explain the thermophysical properties of liquid rare earth metals.

Thakor, P. B.; Sonvane, Y. A.; Patel, H. P.; Jani, A. R.

2013-06-01

30

Hydration Energies and Structures of Alkaline Earth Metal Ions, M2+ (H2O)n, n = 5-7, M = Mg, Ca, Sr, and Ba  

PubMed Central

The evaporation of water from hydrated alkaline earth metal ions, produced by electrospray ionization, was studied in a Fourier transform mass spectrometer. Zero-pressure-limit dissociation rate constants for loss of a single water molecule from the hydrated divalent metal ions, M2+(H2O)n (M = Mg, Ca, and Sr for n = 5–7, and M = Ba for n = 4–7), are measured as a function of temperature using blackbody infrared radiative dissociation. From these values, zero-pressure-limit Arrhenius parameters are obtained. By modeling the dissociation kinetics using a master equation formalism, threshold dissociation energies (Eo) are determined. These reactions should have a negligible reverse activation barrier; therefore, Eo values should be approximately equal to the binding energy or hydration enthalpy at 0 K. For the hepta- and hexahydrated ions at low temperature, binding energies follow the trend expected on the basis of ionic radii: Mg > Ca > Sr > Ba. For the hexahydrated ions at high temperature, binding energies follow the order Ca > Mg > Sr > Ba. The same order is observed for the pentahydrated ions. Collisional dissociation experiments on the tetrahydrated species result in relative dissociation rates that directly correlate with the size of the metals. These results indicate the presence of two isomers for hexahydrated magnesium ions: a low-temperature isomer in which the six water molecules are located in the first solvation shell, and a high-temperature isomer with the most likely structure corresponding to four water molecules in the inner shell and two water molecules in the second shell. These results also indicate that the pentahydrated magnesium ions have a structure with four water molecules in the first solvation shell and one in the outer shell. The dissociation kinetics for the hexa- and pentahydrated clusters of Ca2+, Sr2+, and Ba2+ are consistent with structures in which all the water molecules are located in the first solvation shell. PMID:16429612

Rodriguez-Cruz, Sandra E.; Jockusch, Rebecca A.

2005-01-01

31

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

PubMed

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

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

2010-04-15

32

Observation of coherent population transfer in a four-level tripod system with a rare-earth-metal-ion-doped crystal  

SciTech Connect

Coherent population transfer in a laser-driven four-level system in a tripod configuration is experimentally investigated with a rare-earth-metal-ion-doped crystal (Pr{sup 3+}:Y{sub 2}SiO{sub 5}). The population transfers observed here indicate that a main process inducing them is not optical pumping, which is an incoherent process inducing population transfer. Moreover, numerical simulation, which well reproduces the experimental results, also shows that the process inducing the observed population transfers is similar to stimulated Raman adiabatic passage (STIRAP) in the sense that this process possesses characteristic features of STIRAP.

Goto, Hayato; Ichimura, Kouichi [Frontier Research Laboratory, Corporate Research and Development Center, Toshiba Corporation, 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, 212-8582 (Japan)

2007-03-15

33

Forward and reverse ion-exchange kinetics for some alkali and alkaline earth metal ions on amorphous zirconium(IV) aluminophosphate  

SciTech Connect

The Nernst-Planck equations are applied to study the ion-exchange kinetics on the surface of zirconium(IV) aluminophosphate for Li{sup +}/H{sup +}, Na{sup +}/H{sup +}, K{sup +}/H{sup +}, Mg{sup 2+}/H{sup +}, Ca{sup 2+}/H{sup +}, and Sr{sup 2+}/H{sup +} exchanges in the forward and reverse directions under the conditions favoring particle diffusion. On the basis of these studies, various physical parameters such as the self-diffusion coefficient (D{sub 0}), the energy of activation (E{sub a}), and the entropy of activation ({Delta}S*) have been determined and a correlation has been made of these parameters with the ion-exchange characteristics of the material. The study gives an insight into the ion-exchange processes going on in the exchanger phase and its potential use in metal ion separations.

Varshney, K.G.; Pandith, A.H.

1999-10-26

34

The rare-earth metals  

Microsoft Academic Search

A brief survey is given of the physical properties of the rare earth metals. In doing this their characteristic structural and magnetic behaviour is described first and this is then followed by an examination of the ways in which these features affect the other properties.

K. N. R. Taylor

1970-01-01

35

Adsorption kinetics and reversibility of linear plasmid DNA on silica surfaces: influence of alkaline earth and transition metal ions.  

PubMed

A quartz crystal microbalance with dissipation monitoring is used to study the adsorption of linear plasmid DNA on silica surfaces and silica surfaces coated with poly-L-lysine (PLL) in solutions containing either alkaline earth (calcium and magnesium) or transition (cobalt, copper, and zinc) metals. Our results show that electrostatic attraction alone does not fully explain the significantly higher adsorption rate of DNA on the positively charged PLL layer in Cu(2+) solution compared to solutions containing Ca(2+), Mg(2+), Co(2+), or Zn(2+). Diffusion coefficients measured by dynamic light scattering reveal that the compactness of plasmid DNA molecules is greater in solutions containing Cu(2+) compared to that of DNA in other divalent electrolyte solutions. When the adsorption rate of plasmid DNA on silica is normalized to the corresponding adsorption rate on PLL-coated surfaces at the same solution condition, the attachment (adsorption) efficiencies are about 0.01 for Ca(2+) or Mg(2), but close to unity for Co(2+), Cu(2+), or Zn(2+). Results from viscoelastic modeling of adsorbed DNA layers suggest that the DNA layer formed in Cu(2+) solutions is thicker and more viscous compared to that formed in Co(2+) solutions. This study demonstrates that plasmid DNA has a strong affinity to Cu(2+), which results in a more compact conformation of DNA molecules compared to the case with the other divalent cations investigated. PMID:20373757

Nguyen, Thanh H; Chen, Kai Loon; Elimelech, Menachem

2010-05-10

36

Interaction of myo-inositol hexakisphosphate with alkali and alkaline earth metal ions: Spectroscopic, potentiometric and theoretical studies  

NASA Astrophysics Data System (ADS)

myo-Inositol hexakisphosphate (Ins P6) interacts strongly with cations, forming soluble complexes and solids, both of which are biologically relevant. We have recently reported advances in this area, showing the importance of the interaction with Mg 2+ and Ca 2+. We now extend the data to Sr 2+ and Ba 2+, which behaved similarly to Mg 2+ and Ca 2+, but giving even less soluble systems. We also describe the interactions with Li +, Na +, K +, Mg 2+, Ca 2+, Sr 2+, and Ba 2+ in a non-interacting medium: these depended strongly on cation charge but only weakly on ionic radius within each series. In addition, we probed structural aspects of Ins P6 compounds with alkaline earth cations, by means of IR and Raman spectroscopy of the solids and computational calculations on the 1:1 complexes of Mg 2+. Both approaches suggested direct and multidentate phosphate-metal coordination. In [Mg(H 2L)(H 2O) 3] 8-, three oxygen atoms from two phosphate groups and three water molecules were predicted to form a roughly octahedral coordination shell; alternate or vicinal phosphate groups were predicted to chelate Mg 2+ depending on whether Ins P6 is in the 5-axial/1-equatorial or the 1-axial/5-equatorial conformation, respectively.

Torres, Julia; Veiga, Nicolás; Gancheff, Jorge S.; Domínguez, Sixto; Mederos, Alfredo; Sundberg, Markku; Sánchez, Agustín; Castiglioni, Jorge; Díaz, Alvaro; Kremer, Carlos

2008-02-01

37

Imestigation ol" Maenons in Rare Earth Metals  

E-print Network

Imestigation ol" Maenons in Rare Earth Metals b\\ Inelastic Neutron Scattering tL Bjerrum Moiler #12;BLANK PAGE #12;Riso Report No. 178 Investigation of Magnons in Rare Earth Metals by Inelastic NeutronN LANGF h. a. dec. #12;Contents Page PREFACE 7 I. INTRODUCTION *> 1. Magnetism of Rare Earth Metals 10 2

38

Nuclear magnetic resonance in rare earth metals  

Microsoft Academic Search

This article describes the study, by nuclear magnetic resonance, of both static and dynamical aspects of the hyperfine interaction in rare earth metals, and illustrates the categories of information that can be obtained by using nuclei as microscopic probes in metallic media. The systems discussed include not only the pure rare earth metals but also their alloys and their metallic

M. A. H. McCausland; I. S. Mackenzie

1979-01-01

39

The electric field gradient in heavy rare earth metals  

Microsoft Academic Search

Estimates of the electric field gradient in heavy rare earth metals have been evaluated from experimental hyperfine interaction data. In addition, the magnetic hyperfine fields are analyzed. In the metals the effective radial integrals r-3>4f of the magnetic and quadrupole hyperfine interaction are reduced at most by 10% compared with the free ion values. The electric field gradients due to

J. Pelzl; Fachbereich Physik

1972-01-01

40

SOLVENT EXTRACTION OF THE RARE-EARTH METAL IONS BY A CONE-SHAPED CALDC[4]ARENE SUBSTITUTED AT THE LOWER RTM BY FOUR CH2P(O)Ph2 LIGANDS  

Microsoft Academic Search

The extraction properties of cone-5,11,17,23-tetra-t-butyl-25,26,27,28-tetrakis(diphenylphosphinoylmethoxy)calix[4]arene (1) in 1,2-dichloroethane towards rare-earth metal ions at 25 °C have been investigated. The slope analysis showed a 1:1 metal\\/ligand ratio for the extracted species (La, Eu, Er and Y). The distribution coefficients increase with the polarity of the diluents : chloroform ? dichioromethane ? 1,2-dichloroethane ? nitrobenzene. In the competitive extraction of 11 rare-earth

M. R. Yaftian; M. Burgard; D. Matt; C. B. Dieleman; F. Rastegar

1997-01-01

41

RARE-EARTH METALS--1997 61.1 RARE-EARTH METALS  

E-print Network

RARE-EARTH METALS--1997 61.1 RARE-EARTH METALS By James B. Hedrick The rare earths are a relatively million, to thulium and lutetium, the least abundant rare-earth elements at about 0.5 parts per million. Scandium, atomic number 21, is the lightest rare-earth element. It is the 31st most abundant element

42

Bioavailability of Metal Ions and Evolutionary Adaptation  

PubMed Central

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

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

2012-01-01

43

Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal  

E-print Network

. Quantum computer hardware is presently being developed based on liquids, atoms, or ions or other particles June 2005 In optically controlled quantum computers it may be favorable to address different qubits computing I. Roos and K. Molmer, Phys. Rev. A 69, 022321 2004 --e.g., for use in quantum computers based

Suter, Dieter

44

Selective and rapid ion-chromatographic determinations of alkaline earth metals and applications to the analysis of baryte  

Microsoft Academic Search

Summary An ion-chromatographic procedure is described for the determination of Mg, Ca and Sr in the presence of an excess of Ba in baryte samples after a soda-potash digestion. The procedure is performed by coupling a strong acid exchanger (based on silica gel) and a post-column derivatisation using PAR-Zn-EDTA reagent and photometric detection at 495 nm. Further optimizations resulted in

Daren Yan; Jingan Zhang; Georg Schwedt

1989-01-01

45

Illuminating Metal Ion Sensors - Benzimidazolesulfonamide Metal Complexes  

PubMed Central

The synthesis, structure, and solution spectroscopy of several 2-sulfonamidophenylbenzimidazole metal complexes is reported. These ligands, which have been reported as selective molecular sensors for Zn2+, readily form complexes with Co2+, Ni2+, Cu2+, and Zn2+. Surprisingly, the ligand adopts different binding modes depending on the metal ion. The work here provides insight into the coordination chemistry of these ligands that may allow for the development of improved metal ion sensors and metalloprotein inhibitors. PMID:20942382

Martin, David; Rouffet, Matthieu

2010-01-01

46

Rare earth metals for automotive exhaust catalysts  

Microsoft Academic Search

The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of

Hirohumi Shinjoh

2006-01-01

47

Rare Earth Metals: Resourcefulness and Recovery  

NASA Astrophysics Data System (ADS)

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.

Wang, Shijie

2013-10-01

48

Adsorption of Ni(II) and Cd(II) from water by novel chelating sponge and the effect of alkali-earth metal ions on the adsorption.  

PubMed

Novel chelating sponge (PVA-M-H) was prepared with polyvinyl alcohol by graft polymerization and nucleophilic substitution. E.A, SEM, FT-IR, (13)CNMR, and XPS analyses were used to characterize PVA-M-H. The equilibrium adsorption capacities of PVA-M-H for Ni(II) and Cd(II) were 65.39 and 125.11mgg(-1), respectively. Within the range of 278-308K, the adsorption enthalpy changes of Ni(II) and Cd(II) on PVA-M-H were about 36.39-37.72kJmol(-1), and the free energy were about -13.27 to -1.7kJmol(-1). Both pseudo-first- and -second-order equations fit the adsorption kinetic curves well, and the initial adsorption rates of Ni(II) and Cd(II) onto PVA-M-H were 17.83 and 34.81mg (gmin)(-1), respectively. Although the presence of alkali-earth metal ions in solution decreased Ni(II) and Cd(II) removal, PVA-M-H still retained more than 60 and 80% of its adsorption capacity even as the concentration of Ca(2+) and Mg(2+) was up to 10mmolL(-1), respectively. Both 0.1M HCl and 0.1M EDTA solution could desorb Ni(II) and Cd(II) from PVA-M-H effectively, and the adsorption capacity of PVA-M-H for Ni(II) and Cd(II) could still maintain more than 90% level without any obvious decrease at the fifth cycle. PMID:24316805

Cheng, Cheng; Wang, Jinnan; Yang, Xin; Li, Aimin; Philippe, Corvini

2014-01-15

49

Rare-Earth-metal methylidene complexes.  

PubMed

Transition-metal carbene complexes have been known for about 50?years and widely applied as reagents and catalysts in organic transformations. In contrast, the carbene chemistry of the rare-earth metals is much less developed, but has attracted the research interest in the recent years. In this field rare-earth-metal alkylidene, especially methylidene, compounds are an emerging class of compounds with a high synthetic potential for organometallic chemistry and maybe in the future also for organic chemistry. PMID:24395606

Kratsch, Jochen; Roesky, Peter W

2014-01-01

50

Synthesis and rare earth metal ion-sensing properties of aza-crown derivative incorporating with diaryl-1,3,4-oxadiazole.  

PubMed

A new fluorescent chemosensor (A18C6-Ox) in which a monoaza-18-crown-6 is linked to a diaryl-1,3,4-oxadiazole fluorophore by a methylene spacer has been synthesized to evaluate binding interaction with the rare earth ions by means of absorption and emission spectrophotometry. Absorption spectra of A18C6-Ox showed a broad band at 289nm and there was no significant change in the presence of Sc3+, La3+, Pr3+, Sm3+, Gd3+, Tb3+, Yb3+ and Lu3+ except for Ce3+ and Eu3+. From the emission spectral change of A18C6-Ox, interaction of the rare earth ions with A18C6-Ox is very strong. The formation of A18C6-Ox complexing with Sc3+, La3+, Pr3+, Sm3+, Gd3+, Tb3+, Yb3+ and Lu3+ leads to an increase in fluorescence intensity of A18C6-Ox, while Ce3+ and Eu3+ ions interact strongly causing fluorescence quenching of A18C6-Ox. In addition, the optimal complexation stoichiometry of the rare earth ions with A18C6-Ox was investigated by the fluorescent titration. PMID:21123106

Yu, Tianzhi; Meng, Jing; Zhao, Yuling; Zhang, Hui; Han, Xiaoqian; Fan, Duowang

2011-01-01

51

Reactivity and Infrared Spectroscopy of Gaseous Hydrated Trivalent Metal Ions  

E-print Network

trivalent rare earth metal ions containing yttrium and all naturally abundant lanthanide metals are formed water cluster via a charge-separation process. This transition occurs over a narrow range of cluster The optical properties of lanthanide metals are strongly affected by interactions with water molecules, which

Cohen, Ronald C.

52

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

Microsoft Academic Search

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

T. W. Ellis; F. A. Schmidt

1995-01-01

53

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

Microsoft Academic Search

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

Timothy W. Ellis; Frederick A. Schmidt

1995-01-01

54

Metal ion complexation by ionizable crown ethers  

SciTech Connect

During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. 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 ability of proton- ionizable crown ethers to function as selective metal ion carriers in liquid membrane transport processes has been examined in both bulk liquid membrane and polymer-supported liquid membrane transport systems. New acyclic and cyclic polyether carboxylic acid resins have been prepared by condensation polymerization and characterized.

Bartsch, R.A.

1990-06-01

55

Development of metallic ion beams using ECRIS  

Microsoft Academic Search

The low energy metallic ion beams find wide applications in various research fields of the materials science. Several metallic ion beams have been developed successfully using the electron cyclotron resonance (ECR) ion source based low energy ion beam facility (LEIBF) at Inter University Accelerator Centre (IUAC), New Delhi. These metallic ion beams were developed by different techniques and utilized for

P. Kumar; G. Rodrigues; P. S. Lakshmy; D. Kanjilal; Beer Pal Singh; R. Kumar

2006-01-01

56

Synthesis and Characterization of Polymers Containing Rare Earth Metals  

Microsoft Academic Search

Europium and terbium salts of methacrylic acid (MA) and octanoic acid (OCA) were prepared by a method similar to that described in the literature. Either Eu(MA)3 or Tb(MA)3 with three double bonds (C?C) was used as a crosslinker containing rare earth metal ions, but the octanoic acid salts were used as additives. The salts were dissolved in methacrylic acid (<20%)

Wen-Ying Xu; Yue-Sheng Wang; Da-Gang Zheng; Shu-Liang Xia

1988-01-01

57

Effect of para-substituents on alkaline earth metal ion extraction by proton di-ionizable calix[4]arene-crown-6 ligands in cone, partial-cone and 1,3-alternate conformations.  

PubMed

Two carboxylic acid or N-(X)sulfonyl carboxamide groups were incorporated into calix[4]arene-crown-6 compounds to afford di-ionizable ligands for use in divalent metal ion separations. Acidities of the N-(X)sulfonyl carboxamide groups were tuned by variation of the electron-withdrawing properties of X. Cone, partial-cone and 1,3-alternate conformations were obtained by different synthetic strategies and their structures verified by NMR spectroscopy. Competitive solvent extractions of alkaline earth metal cations from aqueous solutions into chloroform were performed and the results compared with those reported previously for di-ionizable p-tert-butylcalix[4]arene-crown-6 analogues to probe the influence of the para-substituent on the calix[4]arene scaffold on extraction selectivity and efficiency. PMID:17205177

Zhou, Hui; Liu, Dazhan; Gega, Jerzy; Surowiec, Kazimierz; Purkiss, David W; Bartsch, Richard A

2007-01-21

58

Miniature high current metal ion source  

SciTech Connect

A small, simple ion source for the production of high brightness beams of metal ions is described. A metal vapor vacuum arc discharge is used to establish the high density plasma from which the ion beam is extracted. The source is finger-sized, and can produce pulsed metal ion beams with current up to the 10 ma range. 9 refs., 6 figs.

Brown, I.G.; Galvin, J.E.; MacGill, R.A.; Wright, R.T.

1986-04-01

59

Miniature high current metal ion source  

SciTech Connect

A small, simple ion source for the production of high brightness beams of metal ions is described. A metal vapor vacuum arc discharge is used to establish the high density plasma from which the ion beam is extracted. The source is finger sized, and can produce pulsed metal ion beams with current up to the 10-mA range.

Brown, I.G.; Galvin, J.E.; MacGill, R.A.; Wright, R.T.

1986-10-20

60

Metal ions in circumgalactic medium  

NASA Astrophysics Data System (ADS)

Recent observations show high column densities of metal ions in extended halos of galaxies in the redshift range z˜ 0-3. Interpretation of these observations is critically sensitive to a model of ionization state of the circumgalactic gas. In order to explain observed OVI column densities models with thermal ionization equilibrium require metallicity of the halo gas to be as high as the solar one. As a consequence such extended halos would become the main reservouir of metals and missing. On the other hand, when a time-dependent radiation field of a nearby starburst galaxy is assumed to be the main ionization source observational OVI absorption data can be explained if the circumgaactic halos contain an order of magnitude lower amount of metals. Such a difference is due to a much lower fraction of OVI ions (f(OVI)˜ 0.1) under the thermal collisional ionization equilibrium than reached (typically f(OVI)? 0.4-0.6) in a time-dependent radiation field from the underlying star-forming galaxy superimposed on to the extragalactic background. Therefore we argue that high column densities of OVI recently observed in the halos of staforming galaxies even for low (˜ 0.1 Z_?) metallicities. As a result, the requirements to the sources of oxygen in such extended halos relax to a reasonably conservative level. We discuss a possibility of more advanced study of metal ions in extended galactic haloes using the WSO/Spectrum-UV facility.

Vasiliev, Evgenii; Ryabova, Marina; Shchekinov, Yuri

61

Catalysis using hydrous metal oxide ion exchanges  

DOEpatents

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.

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

1985-01-01

62

Catalysis using hydrous metal oxide ion exchangers  

DOEpatents

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.

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

1983-07-21

63

A discussion on the application and production of metal ion beams.  

PubMed

Metal ion beams, which are used in surface modification of metals and alloys as ion beam micrometallurgy, are promising candidates for advanced applications in semiconductors and insulators. Doping with transition metal and rare-earth metal ions in semiconductors and insulators to form metallic nanoclusters attracted much more attention recently, since their applications in diluted magnetic semiconductors, electroluminescent devices, giant magnetic resistance, etc. In this paper, some experiments for metal ion beams will be presented, and various methods and technologies for the production of metal ion beams will be discussed. PMID:18315270

Ren, Xiaotang; Zhao, Ziqiang; Zhao, Weijiang

2008-02-01

64

Metal ion-containing epoxies  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

65

Upconversion Processes in Transition Metal and Rare Earth Metal Systems  

Microsoft Academic Search

The design and characterization of new luminescent materials is an active area of research. Here we present several current\\u000a topics in the area of upconversion by transition-metal and rare-earth-metal doped halide lattices. Following introduction\\u000a to the necessary background material related to upconversion mechanisms and kinetics, a series of topics are discussed which\\u000a illustrate some key areas of developing interest in

Daniel R. Gamelin; Hans U. Güdel

66

METAL-NON METAL TRANSITIONS /N RARE EARTH COMPOUNDS. EXPERIMENT AND THEORK /.  

E-print Network

, superconductivity, electron-phonon and band theory, to name a few. 2. Properties of normal rare earth metals. - Before discussing rare earth valence instabilities, three relevant general features of rare earth metals

Paris-Sud XI, Université de

67

Impulsive ion acceleration in earth's outer magnetosphere  

SciTech Connect

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.

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

1985-01-01

68

ONDES DE SPIN MAGNETISM IN THE LIGHT RARE EARTH 'METALS  

E-print Network

ONDES DE SPIN MAGNETISM IN THE LIGHT RARE EARTH 'METALS A. R. MACKINTOSH H. C. Mrsted Institute terres rares Ikgeres. Abstract. -The magnetic properties of the light rare earth metals are reviewed the last decade, the magnetism of the heavy rare earth metals is now rather well understood. The magnetic

Boyer, Edmond

69

Reversible photodeposition and dissolution of metal ions  

DOEpatents

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.

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

1994-01-01

70

Hyperfine Interactions in Rare-Earth Metals  

Microsoft Academic Search

Estimates of the hyperfine interaction constants for the rare-earth metals are compiled from electron spin resonance and electron-nuclear double resonance data on salts, and atomic beam measurements on free atoms. Correction terms for second-order effects of the hyperfine structure are considered and shown generally to be small. Comparison with the experimental data (mostly from specific heat measurements below 1°K) shows

B. Bleaney

1963-01-01

71

Metallic ions in the equatorial ionosphere  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

72

Characteristics of thermal decomposition products of rare earth, alkali earth metal and transition metal p -toluenesulfonates  

Microsoft Academic Search

Summary A series of alkali earth (Ca, Ba), lanthanide (La, Ce, Pr, Nd,) and transition metal (Fe, Mn, Co, Ni, Cu, Zn, Cd) p-toluenesulfonates were synthesized. Thermal analysis, infrared spectrophotometry, and XRD powder diffraction patterns were employed to characterize the final thermal decomposition products. By heating in dynamic air atmosphere at 30-850°C, it has been found that the alkali earth

Z.-L. Sun

2005-01-01

73

Rare-earth-metal-semiconductor interfacial reactions: Thermodynamic aspects  

Microsoft Academic Search

Chemical reactions at rare-earth-metal-semiconductor interfaces are discussed based on heats of formation of bulk compounds and estimated heats of adsorption. Photoemission results for rare-earth-metal overlayers on the Si(111), Ge(111), and GaAs(110) surfaces, which have shown valence changes with chemical reactions and clustering of metal atoms, were used to estimate the heats of adsorption. The heats of adsorption of rare-earth metals

A. Fujimori; M. Grioni; J. H. Weaver

1986-01-01

74

Rare-earth-metal dialkynyl dimethyl aluminates.  

PubMed

A new class of rare-earth-metal alkynyl complexes has been prepared. The reactions of the tris(tetramethylaluminate)s of lanthanum, praseodymium, samarium, yttrium, holmium, and thulium, [Ln(AlMe?)?], with phenylacetylene afforded compounds [Ln{(?-C?CPh)?AlMe?}?] (Ln=La (1), Pr (2), Sm (3), Y (4), Ho (5), Tm (6)). All of these compounds have been characterized by NMR spectroscopy, X-ray crystallography, and by elemental analysis. NMR spectroscopic studies of the series of para- magnetic compounds [Ln(AlMe?)?] and [Ln{(?-C?CPh)?AlMe?}?] have also been performed. PMID:23616205

Nieland, Anja; Mix, Andreas; Neumann, Beate; Stammler, Hans-Georg; Mitzel, Norbert W

2013-06-17

75

Rare Earth Metals and Alloys by Electrolytic Methods  

Microsoft Academic Search

Fused salt electrolysis as applied to the production of reactive refractory metals is u useful process for rare earth metals preparation also. The relatively low melting point of some of the rare earth metals and many of their alloys is an advantage here. With great ingenuity, electrolytic cells have been designed and methods developed for the preparation of high melting

N. KRISHNAMURTHY; C. K. GUPTA

2001-01-01

76

Rare Earth Metals and Alloys by Electrolytic Methods  

Microsoft Academic Search

Fused salt electrolysis as applied to the production of reactive refractory metals is a useful process for rare earth metals preparation also. The relatively low melting point of some of the rare earth metals and many of their alloys is an advantage here. With great ingenuity, electrolytic cells have been designed and methods developed for the preparation of high melting

N. KRISHNAMURTHY; C. K. GUPTA

2002-01-01

77

Determination of ion exchange equilibrium constants of strongly acidic resins with alkaline-earth metals by means of the potentiometric titrations technique  

Microsoft Academic Search

A recently developed methodology for the determination of ion exchange equilibrium constants has been applied to ion exchange systems of 1:2 stoichiometry. Potentiometric titrations with variable ionic strength were carried out. Ionic medium titrations were performed for the estimation of the liquid junction potential. The modified Bromley's methodology and the Wilson model were used for the estimation of the activity

Gregorio Borge; Gorka Arana; Luis A. Fernández; Juan M. Madariaga

1999-01-01

78

Effect of metal ions on the activity of green crab ( Scylla serrata) alkaline phosphatase  

Microsoft Academic Search

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters. The present paper deals with the study of the effect of some kinds of metal ions on the enzyme. The positive monovalent alkali metal ions (Li+, Na+ and K+) have no effect on the enzyme; positive bivalent alkaline-earth metal ions (Mg2+,

Qing-Xi Chen; Wen-Zhu Zheng; Jing-Yu Lin; Yan Shi; Wen-Zhang Xie; Hai-Meng Zhou

2000-01-01

79

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

NASA Astrophysics Data System (ADS)

Four new metal coordination complexes, namely, [Na(BTA)]n (1), [K2(BTA)2(?2-H2O)]n (2), and [M(BTA)2(H2O)2]n (M=Ca(II) and Sr(II) for 3 and 4, respectively) [BTA=2-(1H-benzotriazol-1-yl) acetic anion], have been obtained under hydrothermal condition, by reacting the different alkali and alkaline-earth metal hydroxides with HBTA. Complexes 1-4 were structurally characterized by X-ray single-crystal diffraction, EA, IR, PXRD, and thermogravimetry analysis (TGA). These complexes display low-dimensional features displaying various two-dimensional (2D) and one-dimensional (1D) coordination motifs. Complex 1 displays a 2D layer with the thickness of 1.5 nm and possesses a topologic structure of a 11 nodal net with Schläfli symbol of {318}. Complex 2 also shows a thick 2D sheet and its topologic structure is a 9 nodes with Schläfli symbol of {311×42}. Complexes 3 and 4 possess a 1D linear chain and further stack via hydrogen bonding interactions to generate a three-dimensional supramolecular architecture. These results suggest that both the coordination preferences of the metal ions and the versatile nature of this flexible ligand play a critical role in the final structures. The luminescent spectra show strong emission intensities in complexes 1-4, which display violet photoluminescence. Additionally, ferroelectric, dielectric and nonlinear optic (NLO) second-harmonic generation (SHG) properties of 2 are discussed in detail.

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

2014-11-01

80

Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions  

Microsoft Academic Search

Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride,

Ali Toutianoush; Ashraf El-Hashani; Judit Schnepf; Bernd Tieke

2005-01-01

81

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

PubMed

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) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion's 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. PMID:24231223

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

2013-12-13

82

ZnS nanocrystals co-activated by transition metals and rare-earth metals—a new class of luminescent materials  

Microsoft Academic Search

We report on the unique luminescent properties of ZnS nanoparticles co-activated by Cu2+ and rare-earth metallic ions. The co-activated ZnS nanocrystals with varying sizes from 20 to 30Å have been prepared by using a chemical coprecipitation at room temperature. The nanoparticles can be co-doped with copper and rare-earth metallic ions during synthesis without altering X-ray diffraction patterns. However, the doping

Ping Yang; Mengkai Lü; Dong Xü; Duolong Yuan; Guangjun Zhou

2001-01-01

83

Metal ion separations using electrically switched ion exchange  

Microsoft Academic Search

An electrochemical method for metal ion separations, called electrically switched ion exchange (ESIX), is described in this paper. In this method, direct oxidation and reduction of an electroactive film attached to an electrode surface is used to load and unload the film with alkali metal cations. The electroactive films under investigation are nickel hexacyanoferrates, which are deposited on the surface

M. A. Lilga; R. J. Orth; J. P. H. Sukamto; S. M. Haight; D. T. Schwartz

1997-01-01

84

Versatile high current metal ion implantation facility  

SciTech Connect

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.

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

1991-06-01

85

Complex formation in rare-earth metal-propionic acid-diamagnetic salt systems by 1 H NMR spectroscopy  

Microsoft Academic Search

Complex formation of propionic acid with ions of rare-earth metals of the yttrium subgroup (D2O, 5.0 M NaNO3) in the absence and presence of diamagnetic Mg2+ cations was studied by 1H NMR spectroscopy in combination with mathematic simulation of complicated equilibria. Stability constants for monopropionate\\u000a complexes of rare-earth ions decrease when the rare-earth cation and Mg2+ are present in the

I. V. Sukhno; V. Yu. Buz’ko; V. T. Panyushkin

2006-01-01

86

Transition Metal Ions: Charge Carriers that Mediate the Electron Capture Dissociation Pathways of Peptides  

NASA Astrophysics Data System (ADS)

Electron capture dissociation (ECD) of model peptides adducted with first row divalent transition metal ions, including Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+, were investigated. Model peptides with general sequence of ZGGGXGGGZ were used as probes to unveil the ECD mechanism of metalated peptides, where X is either V or W; and Z is either R or N. Peptides metalated with different divalent transition metal ions were found to generate different ECD tandem mass spectra. ECD spectra of peptides metalated by Mn2+ and Zn2+ were similar to those generated by ECD of peptides adducted with alkaline earth metal ions. Series of c-/ z-type fragment ions with and without metal ions were observed. ECD of Fe2+, Co2+, and Ni2+ adducted peptides yielded abundant metalated a-/ y-type fragment ions; whereas ECD of Cu2+ adducted peptides generated predominantly metalated b-/ y-type fragment ions. From the present experimental results, it was postulated that electronic configuration of metal ions is an important factor in determining the ECD behavior of the metalated peptides. Due presumably to the stability of the electronic configuration, metal ions with fully-filled (i.e., Zn2+) and half filled (i.e., Mn2+) d-orbitals might not capture the incoming electron. Dissociation of the metal ions adducted peptides would proceed through the usual ECD channel(s) via "hot-hydrogen" or "superbase" intermediates, to form series of c-/z •- fragments. For other transition metal ions studied, reduction of the metal ions might occur preferentially. The energy liberated by the metal ion reduction would provide enough internal energy to generate the "slow-heating" type of fragment ions, i.e., metalated a-/y- fragments and metalated b-/y- fragments.

Chen, Xiangfeng; Fung, Yi Man Eva; Chan, Wai Yi Kelly; Wong, Pui Shuen; Yeung, Hoi Sze; Chan, T.-W. Dominic

2011-12-01

87

THE METABOLISM OF TRACE METAL IONS  

Microsoft Academic Search

Several pathological connitions in man are characterized by the ; accumulation of large amounts of various trace metal ions, Prior studies ahve ; been directed toward the nutritional aspects of the essential metals. their role ; in enzyme systems, and their interaction with isolated protein frations. Little ; attention has been focused on the mechanisms by which these ions move

Saltman

1958-01-01

88

Pressure-Induced Electronic Phase Transitions Transition Metal Oxides and Rare Earth Metals  

E-print Network

Pressure-Induced Electronic Phase Transitions in Transition Metal Oxides and Rare Earth Metals change us, but we start and end with family" -Anthony Brandt ii #12;Acknowledgements I would like Metal Oxides and Rare Earth Metals by Brian Ross Maddox Electron correlation can affect profound changes

Islam, M. Saif

89

Separation of metal ions from aqueous solutions  

DOEpatents

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.

Almon, Amy C. (Augusta, GA)

1994-01-01

90

Diesel fuel containing rare earth metal and oxygenated compounds  

Microsoft Academic Search

Addition of an oxygenated compound and a diesel fuel soluble form of a rare earth metal has been found to reduce particulate emissions from a diesel fueled engine. Preferred soluble rare earth metal additives include cerium carbonyls such as cerium salts of alkylcarboxylic acids and cyclic carboxylic acids.

A. M. Mourao; C. H. Faist

1985-01-01

91

ChemTeacher: Alkaline Earth Metals = Group 2 (IIA)  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Alkaline Earth Metals page includes resources for teaching students about the discovery, properties, and uses of the alkaline earth metals.

2011-01-01

92

Pseudo ribbon metal ion beam sourcea)  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

93

Pseudo ribbon metal ion beam source.  

PubMed

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. PMID:24593634

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

2014-02-01

94

Multiferroism in rare earth metals-doped BiFeO3 nanowires  

NASA Astrophysics Data System (ADS)

Nanowires are the key multifunctional materials for the development towards device miniaturization and high-density data storage systems for future nanoelectronics. In the present report, multifunctional undoped and rare earth metals ions (Gd3+, Tb3+, Dy3+)-doped BiFeO3 nanowires with 20 nm diameter, have been synthesized by template-assisted colloidal dispersion technique. The effect of the size of synthesized nanowires, as well as, the doping of rare earth ions on the structural, magnetic, dielectric and magnetodielectric properties have been studied. The doping of rare earth metals ions leads to structural transition from rhombohedral to orthorhombic BiFeO3 nanowires. The synthesized nanowires exhibit ferromagnetic nature with high value of saturation magnetization, dielectric constant and magnetodielectric coefficient.

Lotey, Gurmeet Singh; Verma, N. K.

2013-08-01

95

Kinetic approach to evaluate the energy and entropy of activation for the exchange of alkaline earth metal ions on tin(IV) tungstate cation exchanger  

SciTech Connect

A new approach based on the Nernst-Planck equations has been applied to study the reaction kinetics on the surface of tin(IV) tungstate for the Mg(II)-H(I), Ca(II)-H(I), Sr(II)-H(I) and Ba(II)-H(I) exchanges under the conditions favouring a particle diffusion phenomenon. On the basis of these studies the various physical parameters such as the effective diffusion coefficients, activation energies and entropies of activation have been evaluated which give some informations regarding the mechanism of ion-exchange on the surface of inorganic materials. 25 references, 3 figures, 3 tables.

Varshney, K.G.; Khan, A.A.; Varshney, K.; Agrawal, S.

1984-01-01

96

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

SciTech Connect

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.

Song, Woongmo [Sogang University, Seoul; Vaknin, David [Ames Laboratory; Kim, Doseok [Sogang University, Seoul

2013-02-25

97

XAFS analysis of molten rare-earth-alkali metal fluoride systems  

Microsoft Academic Search

X-ray absorption fine structure (XAFS) measurements on rare-earth-alkali metal fluoride systems (0.2 LnF3–0.8 MF: Ln=La, Ce, Nd, Sm; M=Li, Na, K) have been carried out at 300 and 1173K. The local structures around rare-earth-ions in both the solid and liquid phases were evaluated by the curve-fitting analysis, involving anharmonic oscillation effects at the higher temperature. This study revealed that the

S. Watanabe; A. K. Adya; Y. Okamoto; N. Umesaki; T. Honma; H. Deguchi; M. Horiuchi; T. Yamamoto; S. Noguchi; K. Takase; A. Kajinami; T. Sakamoto; M. Hatcho; N. Kitamura; H. Akatsuka; H. Matsuura

2006-01-01

98

Short Wavelength Ion Waves Upstream of the Earth’s Bow Shock  

Microsoft Academic Search

ISEE-1 wide-band electric field data, antenna interference effects have been identified in the ion waves upstream of the earth's bow shock. This identification implies that wavelengths of the upstream ion waves are shorter than the antenna length. The interference effects also provide new measurements of the direction of propagation of the ion waves. The new measurements show that the wave

S. A. Fuselier; D. A. Gurnett

1984-01-01

99

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

Code of Federal Regulations, 2013 CFR

...Applicability: Description of the primary rare earth metals subcategory. 421.270 Section...MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The...

2013-07-01

100

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

Code of Federal Regulations, 2012 CFR

...Applicability: Description of the primary rare earth metals subcategory. 421.270 Section...MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The...

2012-07-01

101

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

102

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

Code of Federal Regulations, 2011 CFR

...Applicability: Description of the primary rare earth metals subcategory. 421.270 Section...MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The...

2011-07-01

103

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

104

Valence state at the surface of rare-earth metals  

Microsoft Academic Search

The valence state of a rare-earth metal surface is investigated by using general properties of the surface tension of metals. Thereby it is concluded that samarium is likely to have a divalent or partly divalent surface on top of its trivalent bulk phase, which agrees with recent spectroscopic observations. Also californium metal is discussed from this point of view. Finally,

Börje Johansson

1979-01-01

105

Electrospray ionization of alkali and alkaline earth metal species. Electrochemical oxidation and pH effects  

PubMed

The utility of electrospray ionization mass spectrometry (ESI-MS) for characterizing dissolved metal species has generated considerable interest in the use of this technique for metal speciation. However, the development of accurate speciation methods based on ESI-MS requires a detailed understanding of the mechanisms by which dissolved metal species are ionized during electrospray. We report how the analysis of alkali and alkaline earth metal species provides new information about some of the processes that affect electrospray ion yield. Selected metal ions and organic ligands were combined in 50 : 50 water-acetonitrile buffered with acetic acid or ammonium acetate and analyzed by flow injection ESI-MS using mild electrospray conditions. Species formed by alkali metal ions with thiol and oxygen-donating ligands were detected in acidic and neutral pH solutions. Electrochemical oxidation of N, N-diethyldithiocarbamate and glutathione during electrospray was indicated by detection of the corresponding disulfides as protonated or alkali metal species. The extent of ligand oxidation depended on solution pH and the dissociation constant of the thiol group. Tandem mass spectrometric experiments suggested that radical cations such as [NaL](+.) (where L=N,N-diethyldithiocarbamate) can be generated by in-source fragmentation of disulfide species. Greater complexation of alkali metals at neutral pH was indicated by a corresponding decrease in the relative abundance of the free metal ion. The number of alkali metal ions bound by glutathione and phthalic acid also increased with increasing pH, in accordance with thermodynamic equilibrium theory. Alkaline earth metal species were detected only in acidic solutions, the absence of 8-hydroxyquinoline complexes being attributed to their relative instability and subsequent dissociation during electrospray. Hence, accurate speciation by ESI-MS depends on experimental conditions and the intrinsic properties of each analyte. Copyright 2000 John Wiley & Sons, Ltd. PMID:10972998

Ross; Ikonomou; Orians

2000-08-01

106

Novel syntergistic agent for selective separation of yttrium from other rare earth metals  

SciTech Connect

An oil-soluble synergistic agent has been developed for the selective separation of yttrium (Y) from the other rare earth metals. The synergistic agent is a polyaminocarboxylic acid alkylderivative and has interfacial activity like that of surfactants. Separation of yttrium from heavy rare earth metals (erbium (Er) and holmium (Ho)) in the presence of the synergistic agent was carried out with a 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester as a carrier using a hollow-fiber membrane extractor. The new agent shows a synergistic effect on the permeation rate of rare earth metals at the oil-water interface. By the addition of a small amount of the agent, the selectivity for yttrium from the two rare earth metals was enhanced remarkably, because of the permeation rate of Y was selectively decreased compared with those of Er and Ho. The synergistic effect is discussed from the viewpoint of the stability constant for rare earth metals and the interfacial activity of the synergistic agent. The difference in interaction between the synergistic agent and rare earth ions at the oil-water interface results in an increase in the separation efficiency.

Miyata, Terufumi; Goto, Masahiro; Nakashio, Fumiyuki [Kyushu Univ., Fukuoka (Japan)

1995-06-01

107

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

NASA Technical Reports Server (NTRS)

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.

Westfall, Richard

1991-01-01

108

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

NASA Astrophysics Data System (ADS)

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.

Westfall, Richard

109

Reactions of 2-mercaptobenzoic acid with divalent alkaline earth metal ions: synthesis, spectral studies, and single-crystal X-ray structures of calcium, strontium, and barium complexes of 2,2'-dithiobis(benzoic acid).  

PubMed

The treatment of MCl(2).nH(2)O (M = Ca, Sr, or Ba) with 2-mercaptobenzoic acid (H-2-MBA) in a 1:2 ratio in an EtOH/H(2)O/NH(3) mixture leads to the formation of extended polymeric solids [[Ca(OOCC(6)H(4)SSC(6)H(4)COO)(H(2)O)(2)].0.5(C(2)H(5)OH)](n)(1), [[Sr(OOCC(6)H(4)SSC(6)H(4)COO)(H(2)O)(2)].0.5(C(2)H(5)OH)](n)(2), and [[Ba(2)(OOCC(6)H(4)SSC(6)H(4)COO)(2)(H(2)O)(2)].0.5H(2)O](n)(3), respectively. In all of the cases, under the reaction conditions employed, the H-2-MBA ligand undergoes thiol oxidation to form 2,2'-dithiobis(benzoic acid) (H(2)-DTBB). While the DTBB forms a 1:1 complex with heavier alkaline earth metals (1-3), only an ammonium salt, [(HOOCC(6)H(4)SSC(6)H(4)COOH)(HOOCC(6)H(4)SSC(6)H(4)COONH(4))] (4), was obtained as the final product in the reaction of H-2-MBA with MgCl(2).6H(2)O. Compounds 1-4 have been characterized with the aid of elemental analysis, thermal analysis, and infrared spectroscopic studies. All of the products are found to be thermally stable and do not melt on heating to 250 degrees C. Thermogravimetry on complexes 1-3 indicates the loss of coordinated and lattice water/solvent molecules below 200 degrees C (for complex 2) or 350 degrees C (for complexes 1 and 3). The solid-state structures of all of the derivatives 1-4 have been established by single-crystal X-ray diffraction studies. The calcium and strontium coordination polymers 1 and 2 are isomorphous. The DTBB ligands in 1 and 2 are hexadentate, and the compounds have a channel structure in which solvent ethanol molecules are included. In compound 3, barium ion forms a complex 3-dimensional coordination polymer where both the carboxylate and the sulfur centers of the DTBB ligands (which are hepta- and octadentate) coordinate to the metal. PMID:11754266

Murugavel, R; Baheti, K; Anantharaman, G

2001-12-31

110

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 ...

111

Upgraded vacuum arc ion source for metal ion implantationa)  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

112

Upgraded vacuum arc ion source for metal ion implantation  

SciTech Connect

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

Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu. [High Current Electronics Institute, Siberian Division of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Brown, I. G. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2012-02-15

113

Metal vapor arc ion plating  

DOEpatents

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.

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

1986-09-09

114

Metal vapor vacuum arc ion sources  

SciTech Connect

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.

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

1990-06-01

115

The study of a fundamental law in extracting metal ions from a rf ion source by applying a plasma chemical reaction  

NASA Astrophysics Data System (ADS)

Experimental metal ions are extracted from a rf ion source by applying a plasma chemical reaction. The process has been generalized into a law; it is used in practicing and many metal ions are extracted, such as: Re+, W+, Mo+, Ta+, Pt+, Pd+, Au+, Ag+, Nb+, Ti+, V+, Cr+, Ni+, Fe+, Cu+, Zn+, Ga+, Ge+, Se+, Si+, Al+, Mg+, Be+, Li+, Bi+, In+, Sn+, Pb+, Cd+, etc., and rare-earth ions Y+, Nd+, Ce+, Sm+, Tm+, Dy+, Gd+, Er+, and so on.

Guibin, Bai; Xiuling, Shi; Zhaoxing, Meng

1992-04-01

116

MAGNETIC PROPERTIES OF RARE EARTH METALS AT VERY LOW TEMPERATURES. Period Covered May 1, 1956July 31, 1957  

Microsoft Academic Search

The magnetic susceptibilities of the rare earth metals Ce, Pr, Nd, Sm, ; Dy, and Yb were measured from 293 deg K down to l.5 deg K. The general results ; indicate that, with the exception of Yb and possibly Eu (not yet measured) the ; ions, which constitute the lattice of the metal, are the same as in the

Leipfinger

1957-01-01

117

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

Microsoft Academic Search

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

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

1986-01-01

118

Structure of a piperidine-modified calix[4]arene derivative and spectral resolution of its interaction with rare earth metals with chemometric methods  

NASA Astrophysics Data System (ADS)

A piperidine-modified calix[4]arene derivative was synthesized and its structure was confirmed with X-ray diffraction data. UV-visible spectroscopy was used to study its molecular recognition of rare earth ions. The results revealed the calix[4]arene derivative could separate tight metal picrate ion pairs by complexation with the rare earth metal ions in tetrahydrofuran. Resolution of the UV-visible spectra with chemometric methods revealed that the derivative and the rare earth ions Eu3+, Dy3+, and Tb3+ formed ML2 complexes with stability constants of 108.26, 108.29, and 107.41 respectively.

Wang, Li; Wang, Xiaoya; Wang, Yanmei

2013-03-01

119

Multiphonon relaxation of rare-earth ions in oxide glasses  

Microsoft Academic Search

Nonradiative decay of excited rare-earth ions by multiphonon emission has been investigated in a series of oxide glasses. Various rare-earth electronic levels were selectively excited by short-duration laser pulses and multiphonon relaxation rates were determined from measurements of fluorescence rise and decay times. Time resolution for fluorescence measurements was 3 nsec, so excited states were probed for which the decay

C. B. Layne; W. H. Lowdermilk; M. J. Weber

1977-01-01

120

Distribution of thermal oxygen ions in the near earth magnetosphere  

NASA Astrophysics Data System (ADS)

Based on eleven years of Cluster particle observations, we investigate the distribution of thermal oxygen ions in the near earth magnetosphere with full spatial coverage between 4 to 20 Re. Averaged oxygen ion fluxes are calculated for three energy ranges (E1: 25-136eV; E2: 136eV-3keV; E3 3-35keV) based on measurements from CIS instrument. In a preliminary analysis, we found that oxygen ions of E1 energy are observed mostly in the Polar Regions flowing toward the nightside with average speed of ~20 km/s at 5 Re. They are accelerated to E2 energy range before they arrive at plasmasheet. Clear dawn-dusk asymmetry is observed in the plasmasheet for oxygen ions of the E1 and E2 energy that they are distributed beyond 10 Re on the duskside and beyond 15 Re on the dawnside, suggesting the transportation from ionosphere to plasmasheet is asymmetric for dawn and dusk sides. These oxygen ions are further accelerated in the plasmasheet to E3 energy range and are transported toward the Earth, while they drift westward. These oxygen ions finally reach the dayside, and then either return to the ionosphere or escape from the dayside magnetopause to magnetosheeth. This study provides background knowledge on complete distribution of thermal oxygen ions in the near earth magnetosphere for the modelling and simulation studies on ionosphere-magnetosphere coupling.

Liu, W.; Cao, J.

2013-12-01

121

Permeation behavior of rare earth metals with a calix[4]arene carboxyl derivative in a hollow-fiber membrane  

Microsoft Academic Search

Extraction of three rare earth metals (Er, Ho and Y) was performed by a microporous hydrophobic hollow-fiber membrane extractor using a novel calix[4]arene carboxyl derivative in toluene. It was found that the permeation rate through the membrane of metal ions with calix[4]arene carboxyl derivative was relatively slow, while the addition of a small amount of sodium ion into the aqueous

Fukiko Kubota; Takahiko Kakoi; Masahiro Goto; Shintaro Furusaki; Fumiyuki Nakashio; Tadashi Hano

2000-01-01

122

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

PubMed

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

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

2013-06-15

123

[Development of trace metal ion analysis].  

PubMed

Analyses of trace biologically essential or toxic ionic compounds found in the environment are very important. However, the lack of sensitivity and interference caused by coexisting components are often serious problems. To determine trace levels of metal ions without the above problems, new preconcentration and analytical methods have been developed. Firstly, three methods for the selective preconcentration of metal ions are shown below: 1) 3-Chloropyridazine-6-carbohydrazide was immobilized on glass beads supports to be used as a column packing material. Multi-metal ions were concentrated on the column and eluted selectively with several buffers and hydrochloric acid. The eluate was analyzed off-line by flame atomized-atomic absorption spectrometry (AAS). This method was able to determine sub-ppb levels of cupper- and cadmium-ions in environmental samples. 2) Salicylideneamino-2-thiophenol was immobilized on the supports. Aluminum ion was concentrated selectively on the column and eluted with nitric acid. The eluate was analyzed off-line by flameless-AAS or on-line by flow injection analysis using pyrocatechol violet for a post-column colorimetric reagent. These methods were able to determine ppb-ppt levels of aluminium in environmental samples and were suitable for its state-analysis. 3) Bathocuproinesulfonic acid was immobilized on the supports. Copper ion was concentrated selectively on the column and eluted with nitric acid. The eluate was analyzed on-line by flow injection analysis using bathocuproinesulfonic acid. This method was able to determine sub-ppb levels of copper in environmental samples. On the other hand, to analyze simultaneously trace metal ions and anions, capillary electrophoresis was performed using ethylenediaminetetraacetic acid as an electrolyte component. Simultaneous determination of several ions in mineral waters was achieved by the system. PMID:11019646

Kobayashi, J

2000-09-01

124

Novel metal ion surface modification technique  

SciTech Connect

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.

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

1990-10-01

125

Structure of liquid transition and rare earth metals S. N. Khanna and F. Cyrot-Lackmann  

E-print Network

L-45 Structure of liquid transition and rare earth metals S. N. Khanna and F. Cyrot-Lackmann Groupe. The difference is particularly large for V, Ti, and rare earth metals which are precisely the metals where

Boyer, Edmond

126

Method for treating rare earth-transition metal scrap  

DOEpatents

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.

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

1992-12-29

127

Method for treating rare earth-transition metal scrap  

DOEpatents

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.

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

1992-12-29

128

Diffraction studies of rare earth metals and superlattices  

Microsoft Academic Search

We review the results of X-ray scattering studies of the rare earth metals and present related new results for superlattices and thin slabs. In rare earth crystals we have observed weak structural modulations which accompany the magnetic ordering. The wave length of this modulation can be derived from a spin-slip model in accordance with symmetry considerations. X-ray scattering of both

J. Bohr; Doon Gibbs; J. D. Axe; D. E. Moncton; K. L. D'Amico; C. F. Majkrzak; J. Kwo; M. Hong; C. L. Chien; J. Jensen

1989-01-01

129

SEPARATING RARE-EARTH METALS BY FUSED SALT ELECTROLYSIS  

Microsoft Academic Search

The separation of rare earth metals was investigated in fused bath ; electrolysis containing a mixture of rare earth chlorides. It was found that at ; all the D\\/sub c\\/ (0.25 to 1.5 amp\\/cm²) and temperatures (850 to 870; 560 to ; 700 un. Concent 85% C) investigated, alloys were obtained that were considerably ; impoverished in La (3 to

L. E. Ivanovskii; N. G. Ilyushchenko; A. F. Plekhanov; V. L. Zyazev

1961-01-01

130

Separation and microdetermination of rare earth metals with N-phenylbenzohydroxamic acid and Xylenol Orange  

Microsoft Academic Search

A simple, sensitive and selective method for solvent extraction and spectrophotometric determination of lanthanum(III), praseodymium(III), neodymium(III) and samarium(III) is described. The rare earth metals are extractable into chloroform solution of N-phenylbenzohydroxamic acid (PBHA) at pH9–10. Various parameters are studied to optimize the extraction conditions. Stoichiometry of the complexes and the effect of various ions is discussed. The molar absorptivity is

P. T. Thomaskutty; Y. K. Agrawal

1987-01-01

131

Rare earth metal salts as potential alternatives to Cr(VI) in the chlorate process  

Microsoft Academic Search

Chromate is today added to industrial chlorate electrolyte, where it forms a thin cathode film of chromium hydroxide that\\u000a hinders unwanted reduction of hypochlorite and chlorate. The aim of this study was to investigate rare earth metal (REM) ions\\u000a as an environmentally friendly alternative to the toxic chromate addition. Potential sweeps and iR-corrected polarisation\\u000a curves were recorded using rotating disc

J. GustavssonL; L. Nylén; A. Cornell

2010-01-01

132

Metal vapor vacuum arc ion source  

SciTech Connect

A high-current ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ion beam is extracted. An ion beam current of up to about 1 A has been measured at an extraction voltage of 25 kV for a range of metallic species spanning the periodic table from lithium to uranium. Multiply ionized charge states are seen up to as high as Q = 6+ in the case of uranium. In the metal vapor vacuum arc, regions of intense current concentration are formed at the cathode, and it is at these regions, the cathode spots, that the cathode material is vaporized and ionized to form a dense, quasi-neutral plasma which plumes away from the cathode surface. The plasma plume is caused to impinge upon a set of extractor grids, and the ion beam is extracted from the streaming metal plasma. A preliminary survey of the performance of the source has been made. We describe here the principle of operation of the source, the source design, and the results of those measurements that we have made to date.

Brown, I.G.; Galvin, J.E.; Gavin, B.F.; MacGill, R.A.

1986-06-01

133

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

PubMed

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

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

2003-04-10

134

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

SciTech Connect

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.

Hashida, Masaki; Sakabe, Shuji; Izawa, Yasukazu [ARCBS, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan) and Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan); Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871 (Japan) and Institute for Laser Technology, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2011-03-15

135

Ion velocity distributions in the vicinity of the current sheet in Earth`s distant magnetotail  

SciTech Connect

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 the 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.

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

1994-04-01

136

Material Removes Heavy Metal Ions From Water  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

137

A new chemical oscillator containing neither metal nor oxyhalogen ions  

Microsoft Academic Search

Essentially all known inorganic chemical oscillators1 contain a metal ion2-4 and\\/or an oxyhalogen ion, in particular, iodate ion3, bromate ion2,5 or chlorite ion6. We report here a new chemical oscillator that is based on sulphur chemistry and contains neither a metal ion nor an oxyhalogen ion. The oscillator does involve elemental oxygen, and in this way it may be related

Maria Burger; Richard J. Field

1984-01-01

138

Magnetism in Rare-Earth Metals and Rare-Earth Intermetallic Compounds  

Microsoft Academic Search

Some of our recent local spin density electronic structure calculations for a number of ferromagnetic rare-earth systems are reviewed. A simplified model of the level densities for rare-earth (R) transition metal (M) intermetallic compounds, RmMn, is used to describe in a simple way the main features of their basic electronic structure. Explicit calculations for LuFe2 and RFe2 (R = Gd-Yb)

Börje Johansson; Lars Nordström; Olle Eriksson; M. S. S. Brooks

1991-01-01

139

Nuclear orientation studies of rare-earth metals  

SciTech Connect

The angular distributions of gamma rays from /sup 166m/Ho and /sup 160/Tb aligned at low temperatures in, respectively, Ho metal and Tb metal have been measured. Large hyperfine splittings, expected for the rare earths, have been deduced from the temperature dependence of the gamma-ray anisotropies. Both samples show a macroscopic magnetic anisotropy that is not consistent with an interpretation in terms of a randomly oriented polycrystalline structure.

Krane, K.S.; Morgan, G.L.; Moses, J.D.

1980-01-01

140

Quantitative aspects of rare earth metal determinations using capillary electrophoresis with indirect absorbance detection  

SciTech Connect

The practical utility of capillary zone electrophoresis with indirect absorbance detection is examined for the separation and quantitation of rare earth metals. Various imidazole derivatives are investigated as to their suitability as running buffer (displaceable) detection ions with {alpha}-hydroxyisobutyric acid functioning as a chelating agent to enhance separations. Parameters important for quantitative analysis, such as limits of detection, relative standard deviation of peak areas, efficiency, resolution, peak shape and linear dynamic range are presented. The influence of sample matrix, method of injection, and background ion identity on these parameters are investigated and discussed.

Colburn, B.A.; Starnes, S.D.; Sepaniak, M.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

1995-04-01

141

Anion-exchange separations of metal ions in thiocyanate media.  

PubMed

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

Fritz, J S; Kaminski, E E

1971-05-01

142

Theory of the Resistance of the Rare Earth Metals  

Microsoft Academic Search

The electrical resistance of the heavy rare earth metals shows strong anomalies at the temperatures where the magnetic order changes. These are most marked in measurements made along the hexagonal axis. A simple theory of the effect is given on the basis of two mechanisms. The spiral spin structures found in these materials cause an exchange field at the conduction

R. J. Elliott; F. A. Wedgwood

1963-01-01

143

The structure of rare earth metals in the liquid state  

Microsoft Academic Search

The structure of liquid rare earth metals (So, La, Ce, Pr, Eu, Gd, Tb and Yb) have been systematically examined by X-ray diffraction at temperatures above their melting points. The structure factors of liquid La, Ce, Pr, Eu and Yb were temperature insensitive in the presently available experimental temperature range. In terms of the usual Fourier analysis, the atomic radial

Y. Waseda; S. Tamaki

1977-01-01

144

Developments of rare earth metal catalysts for olefin polymerization  

Microsoft Academic Search

This review article describes recent developments in rare earth metal complexes as polymerization catalysts, focusing on the polymerization of ethylene and ?-olefins. Most of this kind of catalysts had been based on metallocene type complexes, and their catalytic behaviors are surveyed. Advanced series of half-metallocene and non-Cp type catalyst systems are also summarized.

Yuushou Nakayama; Hajime Yasuda

2004-01-01

145

Detection of Heavy Metal Ions in Drinking Water Using a  

E-print Network

Detection of Heavy Metal Ions in Drinking Water Using a High-Resolution Differential Surface, and clinical toxicology. A number of techniques have been developed over the years for heavy metal ion analysis-resolution differential surface plasmon resonance (SPR) sensor for heavy metal ion detection. The sensor surface

Chen, Wilfred

146

Application of ion implantation in metals and alloys  

Microsoft Academic Search

Ion implantation first became established as a precise method of introducing dopant elements into semiconductors. It is now appreciated that there may be equally important applications in metallic tools or components with the purpose of improving their resistance to wear, fatigue or corrosion. Nitrogen ions implanted into steels pin dislocations and thereby harden the metal. Some metallic ions such as

Dearnaley

1981-01-01

147

Short wavelength ion waves upstream of the earth's bow shock  

NASA Technical Reports Server (NTRS)

The identification and explanation of short wavelength antenna interference effects observed in spacecraft plasma wave data have provided an important new method of determining limits on the wavelength, direction of propagation, and Doppler shift of short wavelength electrostatic waves. Using the ISEE-1 wideband electric field data, antenna interference effects have been identified in the ion waves upstream of the earth's bow shock. This identification implies that wavelengths of the upstream ion waves are shorter than the antenna length. The interference effects also provide new measurements of the direction of propagation of the ion waves. The new measurements show that the wave vectors of the ion waves are not parallel to the interplanetary magnetic field (IMF) as previously reported. The direction of propagation does not appear to be controlled by the IMF. In addition, analysis of the Doppler shift of the short wavelength ion waves has provided a measurement of the dispersion relation. The upper limit of the rest frame frequency was found to be on the order of the ion plasma frequency. At this frequency, the wavelength is on the order of a few times the Debye length. The results of this study now provide strong evidence that the ion waves in the upstream region are Doppler-shifted ion acoustic waves. Previously announced in STAR as N83-36328

Fuselier, S. A.; Gurnett, D. A.

1984-01-01

148

Expansion of an ion cloud in the earth's magnetosphere.  

NASA Technical Reports Server (NTRS)

The initial expansion of a barium ion cloud release in the distant earth's magnetosphere is numerically investigated by means of a computer model with self-consistent electric and magnetic interactions. Initial conditions for the calculations are an expanding neutral cloud that is photoionized with a time constant of 20 sec. The results show that after the first 30 sec, the large fluctuations in the magnetic field and in other parameters are damped out and the magnetic field in the central region of the cloud is reduced to near zero. Also, after only 10 sec, a relatively high central ion density has developed and remains for the duration of the calculations.

Hohl, F.

1973-01-01

149

Interplay of metal ions and urease  

PubMed Central

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

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

2009-01-01

150

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

PubMed

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

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

2009-04-01

151

Effects of ion irradiation in metallic glasses  

Microsoft Academic Search

Application of metallic glasses as structural materials has been limited by their poor ductility. To overcome brittle failure, nanocrystals are intentionally introduced to stabilize the glasses. In this study, we report on the application of ion irradiation to induce nanocrystalization in a Cu50Zr45Ti5 (CZT) alloy. Transmission electron microcopy, microindentation and nanoindentation have been used to characterize the CZT alloy irradiated

Jesse Carter; E. G. Fu; G. Bassiri; B. M. Dvorak; N. David Theodore; Guoqiang Xie; D. A. Lucca; Michael Martin; Mark Hollander; Xinghang Zhang; Lin Shao

2009-01-01

152

PREPARATION AND METALLIC REDUCTION OF RARE-EARTH HALIDES AND OXIDES  

Microsoft Academic Search

The development of techniques for the preparation of high-purity rare-; earth metals is described. Rare-earth metals, excepting samarium, europium, and ; ytterbium, were prepared by converting their oxides to anhydrous chlorides or ; fluorides and reducing the rare-earth halides with active metals such as lithium ; or calcium. High-purity, anhydrous rare-earth chlorides were prepared by ; dissolving the rare-earth oxides

T. T. Campbell; F. E. Block; R. E. Mussler; G. B. Robidart

1960-01-01

153

Spectroscopic investigations of fluoroquinolones metal ion complexes.  

PubMed

The complex formation reaction, between fluoroquinolones (FQ): ciprofloxacin (CPX), enoxacin (ENX), enrofloxacin (ENRX), lomefloxacin (LOMX), levofloxacin (LEVX), ofloxacin (OFX), norfloxacin (NFX), sparfloxacin (SPRX) and aluminum(III), iron(III), copper(II) and zinc(II) ions were investigated. The spectrophotometic titration method in a wide range of pH was utilized for estimation of complex formation equilibrium. The application of Bjerrum method allowed to estimate the complex equilibrium of analyzed species in the reaction mixture. The overall stability constants (logbeta(pqr)) of fluoroquinolones complexes with metal ions were calculated using HYPRERQUAD program. The most stable complexes FQ were created with iron(III) and aluminum(III) and than copper(II) and zinc(II) ions, respectively. The highest values of calculated logbeta(pqr) were obtained for the Me(FQ)3H3 species and the lowest for the Me(FQ)2OH forms. Furthermore, an additional studies have been performed. The effect of the polyvalent metal ions on the complex structure has been investigated. The IR and 1H, 13C and 19F NMR spectroscopy methods were used for the confirmation of the structure of the FQ-Me complex formations. The most significant shifts of signals of 1H NMR spectra of the fluoroquinolones and their complexes were found for the protons substituted in the positions 2, 5 and 8, whereas the 13C NMR spectra showed up the shifts changes for carbon atoms in positions 2, 3, 3a and 4. PMID:23923386

Urbaniak, Bartosz; Kokot, Zenon J

2013-01-01

154

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

PubMed

Four transition metal formate coordination polymers with anionic frameworks, namely, Na[Mn(HCOO)3], K[Mn(HCOO)3], Na2[Cu3(HCOO)8], and K2[Cu5(HCOO)12], were synthesized using a mild solution chemistry approach. Multitemperature single-crystal (100-300 K) and powder X-ray diffraction studies of the compounds reveal structures of large diversity ranging from cubic chiral Na-Mn formate to triclinic Na-Cu formate. The structural variety is caused by the nature of the transition metals, the alkali metal ion templation, and the versatility of the formate group, which offers metal-metal coordination through three different O-C-O bridging modes (syn-syn, syn-anti, anti-anti) in addition to metal-metal bridging via a single oxygen atom. The two manganese(II) compounds contain mononuclear, octahedrally coordinated moieties, but the three-dimensional connectivity between the manganese octahedra is very different in the two structures. The two copper frameworks, in contrast, consist of binuclear and mononuclear moieties (Na-Cu formate) and trinuclear and mononuclear moieties (K-Cu formate), respectively. Procrystal electron density analysis of the compounds indicates one-dimensional K(+)-ion conductivity in K-Mn and K-Cu, and the nature of the proposed potassium ion migration is compared with results from similar analysis on known Na(+) and K(+) ion conductors. K-Mn and Na-Mn were tested as cathode materials, but this resulted in poor reversibility due to low conductivity or structural collapse. The magnetic properties of the compounds were studied by vibrating sample magnetometric measurements, and their thermal stabilities were determined by thermogravimetric analysis and differential thermal analysis. Despite structural differences, the metal formates that contain the same transition metal have similar magnetic properties and thermal decomposition pathways, that is, the nature of the transition metal controls the compound properties. PMID:25233266

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

2014-10-01

155

Rare earth-transition metal scrap treatment method  

DOEpatents

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.

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

1992-02-11

156

Rare earth-transition metal scrap treatment method  

DOEpatents

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.

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

157

Ionospheric ions in the near-Earth magnetotail  

NASA Astrophysics Data System (ADS)

We report studies of the relationship between geomagnetic storms and the spatial distribution of cold ions, mostly of ionospheric origin, in the near-Earth magnetotail using in situ particle and field measurements from the Polar spacecraft, solar wind measurements from the ACE spacecraft, and ground geomagnetic indices, during the years from 2000 to 2005. We find local time and latitude-dependent distributions of the plasma moments of cold ions at various levels of geomagnetic storms characterized by the Sym-H and Dst indices. (1) Denser cold ions were observed at the duskside (N > 10 cm-3 compared with 1 cm-3 on average): consistent with the formation of plasma plumes and enhanced bulge region formed as the cold ions wrapped under corotation. (2) Higher temperatures were observed in the auroral oval regions, and a larger temperature anisotropy was observed at the dawnside. (3) Heating processes were strongest near midnight and in the auroral oval regions, which map to PSBL or CPS, except during extremely high geomagnetic activity levels, when heating occurred at high latitudes toward the dawnside, which map to the plasma mantle or distant magnetotail. We interpret these variations as results of ionospheric outflows and plasmaspheric expansion interacting with enhancements of near-Earth magnetospheric convection and geomagnetic-storm-related heating processes in the magnetotail.

Chen, Sheng-Hsien; Moore, Thomas E.

2008-08-01

158

MAGNETISM AND SUPERCONDUCTIVITY OF ANOMALOUS RARE-EARTH METALS AND ALLOYS  

E-print Network

MAGNETISM AND SUPERCONDUCTIVITY OF ANOMALOUS RARE-EARTH METALS AND ALLOYS B. COQBLIN Laboratoire de impurities. 1. Introduction. -The rare-earth metals can be divided in two groups : - The (( normal )) rare lantha- num are (( anomalous )) rare-earths metals. The same duality exists in alloys with rareearth

Boyer, Edmond

159

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...chemical substance identified as hydrated alkaline earth metal salts of metalloid...

2010-07-01

160

Ion acoustic solitons in Earth's upward current region  

SciTech Connect

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.

Main, D. S.; Scholz, C. [Department of Physics, John Brown University, Siloam Springs, Arkansas 72761 (United States); Newman, D. L. [Center for Integrated Plasma Studies, University of Colorado, Boulder, Colorado 80309 (United States); Ergun, R. E. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303 (United States)

2012-07-15

161

Homometallic rare-Earth metal phosphinidene clusters: synthesis and reactivity.  

PubMed

Two new trinuclear ?3 -bridged rare-earth metal phosphinidene complexes, [{L(Ln)(?-Me)}3 (?3 -Me)(?3 -PPh)] (L=[PhC(NC6 H4 iPr2 -2,6)2 ](-) , Ln=Y (2?a), Lu (2?b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120?°C leads to an unprecedented ortho?C?H bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation. PMID:24311456

Wang, Kai; Luo, Gen; Hong, Jianquan; Zhou, Xigeng; Weng, Linhong; Luo, Yi; Zhang, Lixin

2014-01-20

162

Rare Earth metal-mediated group transfer polymerization of vinylphosphonates.  

PubMed

Recent studies have shown that poly(vinylphosphonate)s are readily accessible by rare earth metal-mediated group transfer polymerization (GTP). This article highlights the progress in this new field and advantages of GTP in comparison to classical anionic and radical polymerization approaches. Late lanthanide metallocenes proved to be efficient initiators and highly active catalysts for vinylphosphonate polymerization yielding polymers of precise molecular weight and low polydispersity. Using this method, our group has developed a surface-initiated GTP to prepare poly(vinylphosphonate) brushes. In combination with different ester cleavage strategies, rare earth metal-mediated GTP is an efficient way to create well-defined high-molecular-weight poly(vinylphosphonic acid). PMID:22777965

Salzinger, Stephan; Rieger, Bernhard

2012-08-28

163

BINARY EXTRACTING AGENTS FOR RARE-EARTH METAL SEPARATION  

Microsoft Academic Search

Extraction is one of the efficient hydrometallurgical technologies used to solve the problem of in- dustrial separation of elements having similar chemical properties, including lanthanides(III). Cation- exchange extracting agents of phosphoric acid dialkyl ether group are characterized by the highest figures of the rare-earth metal separation factors, most often of which di(2-ethylhexyl)phosphoric acid (D2EGF?) is used. There exists the problem

S. N. Kalyakin; V. I. Kuzmin

2009-01-01

164

Growth and Evolution of Electromagnetic Ion Cyclotron Waves in the Presence of Multiple Ion Species in the Earth's Magnetosphere.  

E-print Network

??Electromagnetic ion cyclotron (EMIC) waves are generated by a fundamental plasma instability and interact with multiple particle populations in the Earth's magnetosphere. This dissertation describes… (more)

Lee, Justin H

2014-01-01

165

Metal cation binding to gas-phase pentaalanine: divalent ions restructure the complex.  

PubMed

Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region is found to be conformationally informative; in particular, the frequency of the C?O stretching mode of the terminal carboxyl group is diagnostic for hydrogen bonding of the terminal hydroxyl. The doubly charged alkaline earth metal ions (Ca(2+) and Ba(2+)) enforce a highly structured chelation shell around the metal ion, with six strongly bound Lewis-basic chelation sites, and no hydroxyl hydrogen bonding. With the more weakly binding alkali metal ions (Na(+), K(+), and Cs(+)), structures with intramolecular hydrogen bonds are more favorable, leading to dominance of conformations with lower degrees of metal ion chelation. The favored coordination mode correlates with ionic charge and binding strength but is not related to the ionic radius of the metal ion. PMID:22928606

Dunbar, Robert C; Steill, Jeffrey D; Polfer, Nicolas C; Oomens, Jos

2013-02-14

166

CHEMICAL STRUCTURE AND BONDING, CRYSTAL FIBLD EFFECTS IN RARE EARTH IONS (*)  

E-print Network

CHEMICAL STRUCTURE AND BONDING, CRYSTAL FIBLD EFFECTS IN RARE EARTH IONS (*) I. NOWIK, I. FELNERSmBel3conduitBA4 rare earth isotopes located in cubic In determining the magnetic behavior of rare earth ions has been a subject of many experimental and theoretical

Boyer, Edmond

167

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

PubMed

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

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

168

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

PubMed

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

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

2013-11-01

169

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

PubMed Central

Within the three-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules to form chelates. These interactions help the RNA adopt and maintain specific conformations and frequently make essential contributions to function. Defining the locations of these site-bound metal ions remains challenging despite the growing database of RNA structures. Metal-ion rescue experiments have provided a powerful approach to identify and distinguish catalytic metal ions within RNA active sites, but the ability of such experiments to identify metal ions that contribute to tertiary structure acquisition and structural stability is less developed and has been challenged. Herein, we use the well-defined P4–P6 RNA domain of the Tetrahymena group I intron to reevaluate prior evidence against the discriminatory power of metal-ion rescue experiments and to advance thermodynamic descriptions necessary for interpreting these experiments. The approach successfully identifies ligands within the RNA that occupy the inner coordination sphere of divalent metal ions and distinguishes them from ligands that occupy the outer coordination sphere. Our results underscore the importance of obtaining complete folding isotherms and establishing and evaluating thermodynamic models in order to draw conclusions from metal-ion rescue experiments. These results establish metal-ion rescue as a rigorous tool for identifying and dissecting energetically important metal-ion interactions in RNAs that are noncatalytic but critical for RNA tertiary structure. PMID:22539523

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

2012-01-01

170

Silica-Polyamine Composite Materials for Heavy Metal Ion Removal, Recovery, and Recycling. II. Metal Ion Separations from Mine Wastewater and Soft Metal Ion Extraction Efficiency  

Microsoft Academic Search

Silica-polyamine composites have been synthesized which have metal ion capacities as high as 0.84 mmol\\/g for copper ions removed from aqueous solutions. In previous reports it has been demonstrated that these materials survive more than 3000 cycles of metal ion extraction, elution, and regeneration with almost no loss of capacity (less than 10%). This paper describes two modified silica-polyamine composite

ROBERT J. FISCHER; DAVID PANG; SUSAN T. BEATTY; EDWARD ROSENBERG

1999-01-01

171

Preparation of microcapsules containing rare-earth metal elements.  

PubMed

Microcapsules for internal radiation therapies containing the rare-earth metal elements Dy, Ho and Cu with a diameter of 5-10 microm were successfully obtained by an interfacial polymerization method and a successive sedimentation technique was employed to fractionate the microcapsules. A triisocyanate monomer and tricresylphosphate were used for a wall forming material and a core solvent for the metals, respectively. The amount of the metal elements loaded was measured using a high frequency plasma photoemission apparatus. The beta-ray radioactivity of 1 mg of microcapsules irradiated with a common neutron source is estimated as 370 microCi, which is satisfactorily strong for usual radiotherapy, when microcapsules containing Dy are used. Differential interference microscopy indicated narrow size distribution of the fractionated microcapulses. PMID:11201336

Shimofure, S; Koizumi, S; Ichikawa, K; Ichikawa, H; Dobashi, T

2001-01-01

172

Semicondutor quantum dots-based metal ion probes  

NASA Astrophysics Data System (ADS)

Semiconductor quantum dots (QDs) exhibit unique optical and photophysical properties that offer significant advantages over organic dyes as optical labels for chemo/bio-sensing. This review addresses the methods for metal ion detection with QDs, including photoluminescent, electrochemiluminescent, photoelectrochemical, and electrochemical approaches. The main mechanisms of direct interaction between QDs and metal ions which lead to photoluminescence being either off or on, are discussed in detail. These direct interactions provide great opportunities for developing simple yet effect metal ion probes. Different methods to design the chemically-modified QD hybrid structures through anchoring metal ion-specific groups onto the surface of QDs are summarized. Due to the spatial separation of the luminescence center and analyte recognition sites, these chemically-modified QDs offer greatly improved sensitivity and selectivity for metal ions. Several interesting applications of QD-based metal ion probes are presented, with specific emphasis on cellular probes, coding probes and sensing with logic gate operations.

Wu, Peng; Zhao, Ting; Wang, Shanling; Hou, Xiandeng

2013-12-01

173

Predicting wear and blood metal ion levels in metal-on-metal hip resurfacing.  

PubMed

Suboptimal component position and design are thought to lead to edge wear and raised blood metal ion levels in metal-on-metal hip resurfacing (MOM-HR). These factors are thought to influence the "contact patch to rim distance" (CPRD), and calculation of this distance may improve prediction of wear and blood metal ion levels. We measured blood cobalt and chromium ion levels and the wear rates of the bearing surfaces in 165 MOM-HR retrieval cases. We then determined the contribution and effect sizes of cup inclination and version angles, component size and design, and CPRD (calculated from case-specific data) on blood metal ion levels and component wear rates. Acetabular orientation explained between 16.3% and 28.5% of the variation in wear rates and metal ion levels, whereas component size and design explained between 7.3% and 21.8% of the variability. In comparison, CPRD explained up to 67.7% of the variability, significantly greater than any other variable (all p < 0.0001). CPRD is a good predictor of wear and improves our understanding of wear performance and the mechanisms leading to edge loading. PMID:24115200

Matthies, Ashley K; Henckel, Johann; Cro, Suzie; Suarez, Alexander; Noble, Philip C; Skinner, John; Hart, Alister J

2014-01-01

174

Separation of traces of metal ions from sodium matrices  

NASA Technical Reports Server (NTRS)

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.

Korkisch, J.; Orlandini, K. A.

1969-01-01

175

Magnetism of the rare earth, 3d --Theoretical review Abstract. --Compounds of rare earth and transition metals exhibit unusual and quite different behaviour. In  

E-print Network

and secondly those determined mainly by rare earth metals. The first group are those rich in transition metal temperature are much smaller, and magnetic properties bear resemblances with rare earth metals. Thus we of pseudo-binary systems where we mixed two rare earth metals as Y^Gd! _xCo2. As we are interested

Paris-Sud XI, Université de

176

Valence, coordination number, and PAV cells in metallic rare earth compounds F. L. Carter  

E-print Network

Valence, coordination number, and PAV cells in metallic rare earth compounds F. L. Carter Naval, generalized coordination numbers, and Pauling's metallic valences are given for 24 intermetallic rare earth compounds. The results clearly indicate that as much as 33 % rare earth isovalent volume contraction can

Paris-Sud XI, Université de

177

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

PubMed

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

Rout, Alok; Binnemans, Koen

2014-02-28

178

Production and crystal growth of isotopic rare-earth metals  

NASA Astrophysics Data System (ADS)

Large single crystals of high-purity rare-earth metal isotopes 154Sm, 163Dy, and 170Er were obtained by grain growth during high-temperature annealing. Isotopic separation produced about 60 g each of the isotopes in metal oxide form. The isotopic enrichment was 99.5, 96.9, and 96.1% for the 154Sm, 163Dy, and 170Er, respectively. The metal was formed by high-temperature reduction and distillation. Collection efficiency was about 92%, and the total impurity content was <500 ppm by weight. The metal was cast into a button in a water-cooled copper mold using a high-purity, arc-melting facility. Melt losses were about 50 mg for 163Dy and 170Er and 200 mg for 154Sm. The buttons were sealed in argon-filled tantalum cans, heated by induction, and annealed for 96 h at 917, 1375, and 1450 °C for the Sm, Dy, and Er, respectively. Any metal lost from the button was recoverable from the tantalum can interior. The resultant specimens had five to eight single crystal grains. The largest, 163Dy, was about 2.5 × 2.5 × 0.5 cm. All buttons had one or two grains large enough for neutron diffraction experiments. The substructure misorientation was <0.3° as measured by neutron diffraction.

Reed, R. E.; Grisham, W. B.

1972-07-01

179

Plasma immersion surface modification with metal ion plasma  

SciTech Connect

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.

Brown, I.G.; Yu, K.M. (Lawrence Berkeley Lab., CA (USA)); Godechot, X. (Lawrence Berkeley Lab., CA (USA) Societe Anonyme d'Etudes et Realisations Nucleaires (SODERN), 94 - Limeil-Brevannes (France))

1991-04-01

180

A biosystem for removal of metal ions from water  

SciTech Connect

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

Kilbane, J.J. II.

1990-01-01

181

Analytical Study on the Behavior of Ion Thruster Exhausted Plasma in Near Earth Orbit and Its Influence on Earth's Environment  

Microsoft Academic Search

The behavior of exhausted plasma from ion thruster in the near earth orbit was analyzed to find its influence on the earth's environment. It was found by the analysis of the motion of beam plasma using PIC method that the quasineutral state of the exhausted plasma was broken and the charge separation occurred soon after their exhaust because their density

Yoshiki Yamagiwa; Ryoichi Yamamoto; Yuuji Yama

2002-01-01

182

METALLIC HYDRIDES. Magnetic properties of laves-phase rare earth hydrides  

E-print Network

METALLIC HYDRIDES. Magnetic properties of laves-phase rare earth hydrides J. J. Rhyne and G. E on the rare earth site. The rare earth spins disorder at a temperature lower than the bulk Tc in ErFe2 H3 5 per formula unit assuming complete occupation of 3 tetrahedral sites. The heavy rare earth (RFe2

Boyer, Edmond

183

Ion beam analysis of rare earth nitride thin films  

NASA Astrophysics Data System (ADS)

We report compositional measurements on highly disordered GdN, DyN, ErN and SmN thin films, grown using ion-assisted deposition and capped with GaN AlN and Al, grown using the same technique. Ion beam analysis technique of RBS, PIXE and nuclear reaction analysis (NRA) were used to determine the composition of the capped films ex situ, and show that GaN and AlN protects the GdN, DyN and SmN films from oxidation over a timescale of at least a few days. NRA depth profiles indicate that oxygen is incorporated into the films during deposition and is located at the GaN/GdN interface. The ion beam analysis measurements showed that stoichiometric ratios can be obtained and oxygen impurities are significantly reduced by varying the film deposition parameters. The successful protection of the rare earth (RE) nitride films from oxidation allows for a reliable analysis of the RE films in the as-deposited state.

Kennedy, J.; Granville, S.; Markwitz, A.; Ruck, B. J.; Trodahl, H. J.

2008-04-01

184

Origins of energetic ions in the Earth's magnetosheath  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

185

The possible role of metal ions and clays in prebiotic chemistry  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

186

ELECTRODEPOSITION OF RARE-EARTH METALS FROM AQUEOUS AND NONAQUEOUS SOLUTIONS  

Microsoft Academic Search

Electrodeposition of the rare-earth metals in aqueous were found to ; dissolve the anhydrous rare-earth metal salts, but the resuting solutions ; exhibited weak-electrolyte behaviors. Electrolysis did not yield more than small ; quantities of the metals unless mercury was the cathode. (auth);

T. Moeller; P. A. Zimmerman; V. D. Aftandilian; G. W. Cullen; V. D. Galasyn; D. S. Smith; G. C. Giffin

1959-01-01

187

Multiply stripped ion generation in the metal vapor vacuum arc  

SciTech Connect

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

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

1986-08-01

188

Distributions of rare earths and heavy metals in field-grown maize after application of rare earth-containing fertilizer  

Microsoft Academic Search

Rare earths are widely applied in Chinese agriculture to improve crop nutrition through the use of fertilizers, yet little is known of their accumulation in field-grown crops. We have studied the distribution of 16 rare earths (Sc, Y and 14 lanthanide elements) in field-grown maize and the concentration of heavy metals in the grains after application of rare earth-containing fertilizer.

Xingkai Xu; Wangzhao Zhu; Zijian Wang; Geert-Jan Witkamp

2002-01-01

189

Chromatographic Separations of Metal Ions on Zirconium Tungstoarsenate Impregnated Ion-Exchange Papers  

Microsoft Academic Search

A new heteropolyacid salt ion-exchanger, zirconium tungstoarsenate, has been used for preparing impregnated ion-exchange papers. Twenty-nine metal ions have been chromatographed and RF values determined in seven different mixed solvent systems containing 1-propanol and HNO or HCl. On the basis of the difference in selectivities for different metal ions on impregnated papers, a large number of binary and ternary separations

Ajay K. Jain; Sushma Agrawal; Raj P. Singh

1980-01-01

190

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

PubMed

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

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

2013-01-01

191

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

SciTech Connect

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

Oks, Efim [High Current Electronics Institute, Russian Academy of Sciences, 2/3 Academichesky Ave., Tomsk 634055 (Russian Federation); Anders, Andre [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

2010-02-15

192

Saturation magnetic moments, magnetic hyperfine fields and electric field gradients at nuclei in the heavy rare earth metals  

Microsoft Academic Search

The contributions of 4f, 5d and 6s electrons to the saturation magnetic moments and magnetic hyperfine fields in the heavy rare earth metals are calculated using the model described in the previous paper. It is found that 4f shell moments are reduced from their free ion values by amounts varying from 0.05µB in Gd to several tenths of a Bohr

D. M. Eagles

1975-01-01

193

Average properties of the magnetic reconnection ion diffusion region in the Earth's magnetotail: The 20012005 Cluster  

E-print Network

Average properties of the magnetic reconnection ion diffusion region in the Earth's magnetotail (2010), Average properties of the magnetic reconnection ion diffusion region in the Earth's magnetotail; published 14 August 2010. [1] Magnetic reconnection plays a key role in the circulation of plasma through

California at Berkeley, University of

194

Local order around rare earth ions during the devitrification of oxyfluoride glasses  

E-print Network

Local order around rare earth ions during the devitrification of oxyfluoride glasses Maurício A. P EXAFS measurements were performed on rare earth doped fluorosilicate and fluoroborate glasses and glass. Molecular dynamics simulations of the devitrification process of a lead fluoride glass doped with Er3+ ions

Boyer, Edmond

195

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

SciTech Connect

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.

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

1988-01-01

196

Reusable chelating resins concentrate metal ions from highly dilute solutions  

NASA Technical Reports Server (NTRS)

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.

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

1966-01-01

197

Ion exchange and redox reactions in metal-ion exchanger nanocomposites  

NASA Astrophysics Data System (ADS)

The reducing sorption of oxygen dissolved in water with the use of metal-containing nanocomposites is considered taking into account the bifunctional nature of sorbents possessing both redox and ion exchange properties. A physicochemical model of the process including metal particle dispersity, their distribution over a grain, and the special features of the chemical oxidation of metals was used. Based on this model, a mathematical formulation of the problem including the stage of the interdiffusion of metal ions (metal oxidation products) and hydrogen ions (matrix counterions) is given.

Kipriyanova, E. S.; Konev, D. V.; Kravchenko, T. A.; Khorol'skaya, S. V.

2012-07-01

198

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

PubMed Central

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

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

2002-01-01

199

Selective transformations of cyclopentadienyl ligands of transition-metal and rare-earth metal complexes.  

PubMed

Cyclopentadienyl and substituted cyclopentadienyl ligands are observed in a wide range of organometallic complexes. In addition to serving as ancillary ligands, these ligands have come into their own as intermediates in organometallic reactions, and shown many unique reaction modes involving ring C-H, C-C and C=C bond cleavages. This feature article summarizes the progressive development of cyclopentadienyl-based reactions of metallocene complexes of transition metals and rare-earth metals, with the aim of further developing the fundamental modes of reactivity of such systems together with their synthetic applications. PMID:23323264

Liu, Ruiting; Zhou, Xigeng

2013-04-21

200

The DNA-binding and bioactivity of rare earth metal complexes.  

PubMed

Recently more and more attention is paid to the rare earth metal complexes, because the properties of the rare earth metals are similar to those of the transition metals such as the similar atomic and the ionic radius. A large number of rare metal complexes were synthesized, and their bioactivities were also studied. This review highlights recent researches on the interaction of some rare earth metal complexes with DNA, analyzes how the configuration of the complexes influences the binding affinity, and focuses on the pharmacological activities of the complexes, such as anticancer, antibacterial, antioxidant, anti-inflammatory and anti-virus. PMID:24568297

Yang, Li; Wang, Bochu; Tan, Jun; Zhu, Liancai

2013-08-01

201

Determination of Trace Metal Ion Concentrations in Seawater  

NASA Astrophysics Data System (ADS)

An experimental procedure is described for the pre-concentration of trace metal ions from seawater. The procedure is suitable for senior students in analytical chemistry/instrumental analysis. Hydrated iron (III) oxide is recommended for the coprecipitation of trace transition metal ions from aqueous solution. Chelating ion-exchange with Chelex-100 is similarly recommended. Both techniques have been successfully used here. After leaching the precipitate or desorbing the resin with nitric acid solution, the trace metal ion content of the concentrate is determined using a suitably sensitive analytical technique such as graphite furnace atomic absorption spectrophotometry. The values obtained are used to calculate the concentration of trace metal ions in the seawater.

Quigley, Michael N.; Vernon, Fredrick

1996-07-01

202

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

203

Adhesive bonding of ion beam textured metals and fluoropolymers  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

204

Progress in metal ion separation and preconcentration : an overview.  

SciTech Connect

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.

Bond, A. H.

1998-05-19

205

Silica-polyamine composite materials for heavy metal ion removal, recovery, and recycling. 2. Metal ion separations from mine wastewater and soft metal ion extraction efficiency  

SciTech Connect

Silica-polyamine composites have been synthesized which have metal ion capacities as high as 0.84 mmol/g for copper ions removed from aqueous solutions. In previous reports it has been demonstrated that these materials survive more than 3,000 cycles of metal ion extraction, elution, and regeneration with almost no loss of capacity (less than 10%). This paper describes two modified silica-polyamine composite materials and reveals the results of tests designed to determine the effectiveness of these materials for extracting and separating metal ions from actual mining wastewater samples. Using these materials, the concentration of copper, aluminum, and zinc in Berkeley Pit mine wastewater is reduced to below allowable discharge limits. The recovered copper and zinc solutions were greater than 90% pure, and metal ion concentration factors of over 20 for copper were realized. Further, the ability of one of these materials to decrease low levels of the soft metals cadmium, mercury, and lead from National Sanitation Foundation recommended challenge levels to below Environmental Protection Agency allowable limits is also reported.

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

1999-12-01

206

ANALYSIS OF THE ELECTRON EXCITATION SPECTRA IN HEAVY RARE EARTH METALS, HYDRIDES AND OXIDES  

E-print Network

397 ANALYSIS OF THE ELECTRON EXCITATION SPECTRA IN HEAVY RARE EARTH METALS, HYDRIDES AND OXIDES C thin evaporated foils of heavy rare earths (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in three different chemical of high energy incident electrons (75 keV) transmitted through thin foils of yttric rare earth elements

Boyer, Edmond

207

Rare earth-transition metal alloy permanent magnet materials: 1960–1985  

Microsoft Academic Search

Rare earths, primarily light rare earths, either alone or in combination with other rare earths, as in misch metal, alloyed with cobalt or iron, constitute a unique new class of permanent magnet materials with outstanding coercivity and other magnetic properties. These materials represent the first serious alternative to the alnicos and ferrites, discovered earlier. The intensity of interest in this

E. M. T. Velu; E. C. Subbarao

1986-01-01

208

Metal ion acquisition in Staphylococcus aureus: overcoming nutritional immunity  

PubMed Central

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

Cassat, James E.

2013-01-01

209

Correlation between volatility of rare-earth metals and encapsulation of their carbides in carbon nanocapsules  

Microsoft Academic Search

Encapsulation of metals in multilayered graphitic capsules has been studied for all the rare-earth elements (Sc, Y, and Ln = La, Ce, ..., Lu) excluding Pm by using electric arc discharge. Electron microscopy and X-ray diffraction of carbonaceous products revealed that most of rare-earth metals (Sc, Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu) were encapsulated

Yahachi Saito; Mitsumasa Okuda; Tadanobu Yoshikawa; Atsuo Kasuya; Yuichiro Nishina

1994-01-01

210

Novel Synergistic Agent for Selective Separation of Yttrium from Other Rare Earth Metals  

Microsoft Academic Search

An oil-soluble synergistic agent has been developed for the selective separation of yttrium (Y) from the other rare earth metals. The synergistic agent is a polyaminocarboxylic acid alkylderivative and has interfacial activity like that of surfactants. Separation of yttrium from heavy rare earth metals [erbium (Er) and holmium (Ho)] in the presence of the synergistic agent was carried out with

Terufumi Miyata; Masahiro Goto; Fumiyuki Nakashio

1995-01-01

211

Solvent extraction of rare-earth metals by carboxylic acids  

SciTech Connect

The solvent extraction of the trivalent lanthanides and yttrium from nitrate media by solutions of carboxylic acids in xylene has been studied. Commercially available carboxylic acids such as Versatic 10 and naphthenic acids were used, as well as model compounds of known structure, such as 2-ethylhexanoic and 3-cyclohexylpropanoic acids. In a few cases, extraction of the metals from sulphate and chloride solutions was also investigated. The dependence of the extraction properties of the carboxylic acids on the atomic number of the lanthanide shows a definite relationship to the steric bulk of the carboxylic acid molecule quantified by means of the steric parameter, E{sub s}{prime} of the substituent alkyl group. The stoichiometries of the extracted complexes for representative light (La), middle (Gd) and heavy (Lu) rare-earth metals were investigated by the slope-analysis technique for a sterically hindered acid (Versatic 10 acid; -E{prime}{sub s} = 3.83) and an acid with low steric hindrance (3-cyclohexylpropanoic acid; -E{prime}{sub s} = 0.28). 14 refs., 13 figs., 3 tabs.

Preez, A.C. du; Preston, J.S. [Mintek, Randburg (South Africa)

1992-04-01

212

Metal ion removal from aqueous solution using physic seed hull.  

PubMed

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

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

2010-07-15

213

Incorporation of impurity metal ions in electrolytic manganese dioxide  

SciTech Connect

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.

Tamura, Hiroki; Ishizeki, Kenji; Nagayama, Masaichi; Furuichi, Ryusaburo (Hokkaido Univ., Sapporo (Japan). Faculty of Engineering)

1994-08-01

214

Pseudomonas aeruginosa immobilized multiwalled carbon nanotubes as biosorbent for heavy metal ions.  

PubMed

Pseudomonas aeruginosa immobilized multiwalled carbon nanotubes has been used as biosorbent for the solid phase extraction of some heavy metal ions in environmental samples. Cobalt(II), cadmium(II), lead(II), manganese(II), chromium(III) and nickel(II) ions have been selected as analytes for the presented study, due to their important negative and positive roles in human life. In order to investigate quantitative biosorption conditions of the analytes, the influences of pH of the aqueous solution, eluent type, eluent volume, samples volume, etc. were examined. The effects of alkaline, earth alkaline and some transitions metals on the biosorption of analyte ions on P. aeruginosa immobilized multiwalled carbon nanotubes were also investigated. The presented biosorption procedure was applied to the determination of analytes in tomato leaves, bovine liver, boiled wheat, canned fish, black tea, lichen and natural water samples. PMID:17532628

Tuzen, Mustafa; Saygi, Kadriye Ozlem; Usta, Canan; Soylak, Mustafa

2008-04-01

215

The role of metal corrosion in inflammatory processes: induction of adhesion molecules by heavy metal ions  

Microsoft Academic Search

Prosthetic devices undergo corrosion processes after implantation including the release of certain amounts of metal ions into the adjacent tissues. On reaching the bloodstream, a systemic influence of those ions may be envisaged. Cell adhesion molecules (CAMs) are recognized as an essential component of the mechanisms of endothelial damage. To study the influence of selected heavy metals on human umbilical

C. L. Klein; P. Nieder; M. Wagner; H. Köhler; F. Bittinger; C. J. Kirkpatrick; J. C. Lewis

1994-01-01

216

Influence of rare-earth metals on the physicomechanical properties of steel in thermomechanical working  

SciTech Connect

The authors study the stabilizing influence of rare-earth metals on the structural condition of thermomechanically worked steels. 45, 60, U8A, 50KhGA, and 70S2KhA steels were used for the investigation. The rare-earth metals used were lanthanum, cerium, and a mixture of rare-earth metals called mischmetal. Impact strength tests of Mesnager specimens at room temperature showed that the favorable influence of high-temperature thermomechanical working is strengthened with an increase in carbon content in the steel. Results are shown of investigations at sub-zero temperatures of Charpy specimens with an initiated fatigue crack. Rare-earth metal microadditions are shown to have a good influence on the structurally sensitive characteristics of the steel, the contact strength and the corrosion resistance. Rare-earth metals also retard the development of the recrystallization processes of the deformed austenite.

Kotrechko, A.A.; Opal'chuk, A.S.; Kozyrskii, O.I.; Semenovskii, A.A.; Khrunik, R.A.; Katsov, K.B.; Kokotailo, I.V.

1987-07-01

217

Ion exchange extraction of heavy metals from wastewater sludges.  

PubMed

Heavy metals are common contaminants of some industrial wastewater. They find their way to municipal wastewaters due to industrial discharges into the sewerage system or through household chemicals. The most common heavy metals found in wastewaters are lead, copper, nickel, cadmium, zinc, mercury, arsenic, and chromium. Such metals are toxic and pose serious threats to the environment and public health. In recent years, the ion exchange process has been increasingly used for the removal of heavy metals or the recovery of precious metals. It is a versatile separation process with the potential for broad applications in the water and wastewater treatment field. This article summarizes the results obtained from a laboratory study on the removal of heavy metals from municipal wastewater sludges obtained from Ardhiya plant in Kuwait. Data on heavy metal content of the wastewater and sludge samples collected from the plant are presented. The results obtained from laboratory experiments using a commercially available ion exchange resin to remove heavy metals from sludge were discussed. A technique was developed to solubilize such heavy metals from the sludge for subsequent treatment by the ion exchange process. The results showed high efficiency of extraction, almost 99.9%, of heavy metals in the concentration range bound in wastewater effluents and sludges. Selective removal of heavy metals from a contaminated wastewater/sludge combines the benefits of being economically prudent and providing the possibility of reuse/recycle of the treated wastewater effluents and sludges. PMID:15027828

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

2004-01-01

218

Extracting metal ions with diphosphonic acid, or derivative thereof  

DOEpatents

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.

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

1994-01-01

219

Modeling Multi-Metal Ion Exchange in Biosorption  

E-print Network

by protonated Sargassum fluitans biomass in systems containing two metal ions and protons at different pH values by the brown alga Sargassum fluitans, which contains the carboxyl groups of alginate and the sulfate groups

Volesky, Bohumil

220

Metallic glass as a temperature sensor during ion plating  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

221

Metallic glass as a temperature sensor during ion plating  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

222

Smart textile device using ion polymer metal compound.  

PubMed

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

Nakamura, Taro; Ihara, Tadashi

2013-01-01

223

Removal of toxic metal ions from wastewater by semiconductor photocatalysis  

Microsoft Academic Search

Semiconductor photocatalytic reduction is a relatively new technique for the removal of dissolved metal ions in wastewater. In this paper, physical adsorption and photocatalytic reduction of eight environmentally significant metal ions in TiO2 suspensions of Degussa P25 and Hombikat UV100 were investigated. Critical scrutiny of the potential versus pC and pH diagrams reveals that any particular oxidation or reduction reaction

Dingwang Chen; Ajay K. Ray

2001-01-01

224

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

USGS Publications Warehouse

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.

Hedrick, J. B.

1997-01-01

225

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

USGS Publications Warehouse

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.

Hedrick, James, B.

1997-01-01

226

Metal ion implantation for large scale surface modification  

SciTech Connect

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

Brown, I.G.

1992-10-01

227

Release characteristics of alkali and alkaline earth metallic species during biomass pyrolysis and steam gasification process.  

PubMed

Investigating the release characteristics of alkali and alkaline earth metallic species (AAEMs) is of potential interest because of AAEM's possible useful service as catalysts in biomass thermal conversion. In this study, three kinds of typical Chinese biomass were selected to pyrolyse and their chars were subsequently steam gasified in a designed quartz fixed-bed reactor to investigate the release characteristics of alkali and alkaline earth metallic species (AAEMs). The results indicate that 53-76% of alkali metal and 27-40% of alkaline earth metal release in pyrolysis process, as well as 12-34% of alkali metal and 12-16% of alkaline earth metal evaporate in char gasification process, and temperature is not the only factor to impact AAEMs emission. The releasing characteristics of AAEMs during pyrolysis and char gasification process of three kinds of biomass were discussed in this paper. PMID:22525260

Long, Jiang; Song, Hu; Jun, Xiang; Sheng, Su; Lun-Shi, Sun; Kai, Xu; Yao, Yao

2012-07-01

228

Pressure-induced valence change in the rare earth metals: The case of Praseodymium ?  

E-print Network

The rare earth metal praseodymium (Pr) transforms from the d-fcc crystal structure (Pr-III) to ?-U one (Pr-IV) at 20 GPa with a large volume collapse (?V/V = 0.16), which is associated with the valence change of the Pr ion. The two 4f electrons in the Pr ion is supposed to be itinerant in the Pr-IV phase. In order to investigate the electronic state of the phase IV, we performed the high pressure electrical resistance measurement using the diamond anvil cell up to 32 GPa. In the Pr-IV phase, the temperature dependence of the resistance shows an upward negative curvature, which is similar to the itinerant 5f electron system in actinide metals and compounds. This suggests the narrow quasiparticle band of the 4f electrons near the Fermi energy. A new phase boundary is found at T0 in the Pr-IV phase. From the temperature and magnetic field dependences of the resistance at 26 GPa, the ground state of the Pr-IV phase is suggested to be magnetic. Several possibilities for the origin of T0 are discussed.

Naoyuki Tateiwa A; Kazuyoshi Takeda B C

2005-01-01

229

Oligomeric rare-earth metal cluster complexes with endohedral transition metal atoms  

NASA Astrophysics Data System (ADS)

Comproportionation reactions of rare-earth metal trihalides (RX3) with the respective rare-earth metals (R) and transition metals (T) led to the formation of 22 oligomeric R cluster halides encapsulating T, in 19 cases for the first time. The structures of these compounds were determined by single-crystal X-ray diffraction and are composed of trimers ({T3R11}X15-type, P63/m), tetramers ({T4R16}X28{R4} (P-43m), {T4R16}X20 (P42/nnm), {T4R16}X24(RX3)4 (I41/a) and {T4R16}X23 (C2/m) types of structure) and pentamers ({Ru5La14}2Br39, Cc) of {TRr}n (n=2-5) clusters. These oligomers are further enveloped by inner (Xi) as well as outer (Xa) halido ligands, which possess diverse functionalities and interconnect like oligomers through i-i, i-a and/or a-i bridges. The general features of the crystal structures for these new compounds are discussed and compared to literature entries as well as different structure types with oligomeric T centered R clusters. Dimers and tetramers originating from the aggregation of {TR6} octahedra via common edges are more frequent than trimers and pentamers, in which the {TRr} clusters share common faces.

Steinberg, Simon; Zimmermann, Sina; Brühmann, Matthias; Meyer, Eva; Rustige, Christian; Wolberg, Marike; Daub, Kathrin; Bell, Thomas; Meyer, Gerd

2014-11-01

230

Extraction of rare earth metals by calix[4]arene solubilized in AOT reversed micellar solution  

Microsoft Academic Search

Extraction of rare earth metals (europium and yttrium) and their separation from zinc were investigated using a novel host compound, p-tert-octylcalix[4]arene carboxyl derivative as an extractant. Extraction behavior of the metals with a typical commercial extractant PC-88A or Versatic 10 was also examined. The cyclic ligand calixarene showed a high selectivity towards rare earth metals compared with PC-88A and Versatic

F Kubota; K Shinohara; K Shimojo; T Oshima; M Goto; S Furusaki; T Hano

2001-01-01

231

Redox reactions in molten electrolytes containing chlorides of rare-earth metals  

Microsoft Academic Search

Solutions of rare-earth metals (REM, Ln) in molten chlorides, including mixtures MCl + LnCl3, where M stands for an alkali metal, are studied by methods of potentiometry, voltammetry, and conductimetry in broad intervals\\u000a of concentration and temperature. The results that had been obtained give sufficiently comprehensive and reliable enough information\\u000a concerning the valence state of rare-earth metals, as well as

V. A. Khokhlov; A. V. Novoselova; E. V. Nikolaeva; O. Yu. Tkacheva; A. B. Salyulev

2007-01-01

232

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

SciTech Connect

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.

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

2007-01-01

233

Oxidative mechanisms in the toxicity of metal ions  

Microsoft Academic Search

The role of reactive oxygen species, with the subsequent oxidative deterioration of biological macromolecules in the toxicities associated with transition metal ions, is reviewed. Recent studies have shown that metals, including iron, copper, chromium, and vanadium undergo redox cycling, while cadmium, mercury, and nickel, as well as lead, deplete glutathione and protein-bound sulfhydryl groups, resulting in the production of reactive

S. J. Stohs; D. Bagchi

1995-01-01

234

Influence of electrode geometry on liquid metal ion source performance  

Microsoft Academic Search

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

L. W. Swanson; J. Z. Li

1988-01-01

235

Synergistic Catalysis of Dimetilan Hydrolysis by Metal Ions and  

E-print Network

such as extracellular enzymes. Introduction Hydrolysis is believed to be the predominant degradation pathway that dissolved metal ions (1), simple hydrous metal oxides (2-5), and clays (6, 7) can increase hydrolysis rates of agrochemicals dramatically. Catalysis may arise from reaction of the added chemical constituent with the agro

Huang, Ching-Hua

236

Surface Precipitation of Hydrolyzable Metal Ions on Oxide Surfaces  

E-print Network

Surface Precipitation of Hydrolyzable Metal Ions on Oxide Surfaces S. E. Fendorf Heavy metalO2 and TiO2 near and beyond monolayer coverage. Surface precipitation of Al(III) and La(III) was observed on MnO2, but was not apparent on TiO2 nor in bulk solution. Al(III) formed a surface precipitate

Sparks, Donald L.

237

Dissociative Grazing Scattering of H2 + Ions from Metal Surfaces  

E-print Network

Dissociative Grazing Scattering of H2 + Ions from Metal Surfaces Igor Wojciechowski, Marina from grazing scattering of H2 + from metal surfaces are calculated analytically and by using classical are typical for the activation of chemical reactions on a surface. Thus, the use of grazing scattering

238

Removal of metal ions from aqueous solution  

DOEpatents

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.

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

239

Removal of metal ions from aqueous solution  

DOEpatents

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.

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

240

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

PubMed

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

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

2014-02-01

241

Refinement of Cast Microstructure of Hypereutectic Al-Si Alloys Through the Addition of Rare Earth Metals  

Microsoft Academic Search

Microstructural observation and thermal analysis of Al-21 wt % Si alloys with different rare earth metals were performed to examine the effect of rare earth metal on the refinement of primary silicon phase. Simultaneous refinement of both primary and eutectic silicon morphology is achieved with the addition of rare earth and its effect increases with the amount of rare earth

Joonyeon Chang; Inge Moon; Chongsool Choi

1998-01-01

242

Neutralization by Metal Ions of the Toxicity of Sodium Selenide  

PubMed Central

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

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

2013-01-01

243

Thermomagnetic switching in amorphous rare-earth transition metal alloys  

SciTech Connect

Conditions for writing and erasure have been investigated for different amorphous rare-earth transition metal alloys using a simple temperature distribution evaluated for a three-layer structure. The radial and time dependence of the magnetic parameters relevant for the switching process have been calculated by means of the mean-field theory based on experimental data of the saturation magnetization, uniaxial anisotropy, and the coercivity, for alloys of composition (Gd,Tb)/sub 1-//sub x/Fe/sub x/ and Tb/sub 1-//sub x/(Fe,Co)/sub x/. From the radial profiles of the coercive field, maximum domain diameters are extracted in the limit of large domain velocities. Domain-wall stabilities are calculated from the force equation for writing and erasure conditions as a function of applied field yielding margins for stable domains and collapse fields. In addition to bubblelike domains, ring domain configurations are considered, which imply the possibility of direct overwrite for alloys with a compensation temperature above ambient temperature. The switching with a continuous read power level is discussed.

Hansen, P.

1987-07-01

244

Quantum Computing Hardware based on Rare-Earth-Ion Doped Whispering-Gallery Mode Resonators.  

E-print Network

??Rare-earth-ion doped crystals are an interesting system for quantum computing investigations due to their long optical and hyperfine coherence times. In particular, the ground-state coherence… (more)

McAuslan, David Lee

2011-01-01

245

Multiply stripped ion generation in the metal vapor vacuum arc  

SciTech Connect

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 reported 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. 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.

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

1988-05-15

246

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

E-print Network

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

Barrett, Steve D.

247

Sorption of metal ions from aqueous solution using bone char.  

PubMed

The sorption of cadmium, copper and zinc from aqueous solutions onto bone char has been studied in both single and binary multi-component systems. Equilibrium experimental studies have been performed to determine the sorption capacity of bone char for each metal ion. The isotherm results have been analysed using single and multi-component equilibrium models. The rate of sorption of the metal ions onto bone char has been studied using an agitated batch adsorber. The concentration versus time decay curves have been measured and a number of mass transfer models have been developed and tested based on diffusion controlled sorption. The results of the equilibrium and rate studies are presented and discussed in the paper. The possible mechanisms of metal sorption are also discussed. Finally a series of fixed bed column studies have been performed and analysed using a diffusion mass transport model. The experimental results show a displacement effect for the binary metal ion breakthrough curves. PMID:16023725

Choy, Keith K H; McKay, Gordon

2005-08-01

248

Improvement of corrosion resistance of magnesium metal by rare earth elements  

Microsoft Academic Search

Mg metal containing rare earth metals (REs) can be electrowon directly by molten salt electrolysis. The clarification of the optimum RE content in Mg is necessary to fix the electrolytic conditions in the direct electrowinning of Mg with RE. From this point of view, effect of RE addition in Mg metal on its corrosion property was studied in detail in

Toshihide Takenaka; Takami Ono; Yuji Narazaki; Yusuke Naka; Masahiro Kawakami

2007-01-01

249

Highly sensitive chelating agents for histochemical staining of rare earth metals  

Microsoft Academic Search

In tissues, bromopyridylazo-diethylaminophenol has been found to be capable of staining very small amounts of rare earth metals,\\u000a particularly praseodymium, terbium, dysprosium, holmium, ytterbium, and lutetium. Differentiation of a target metal from interfering\\u000a metals was achieved using masking agents, polyphosphates and aminopolycarboxylic acids.

Yawara Sumi; Masanori T. Itoh; Minoru Yoshida; Yoshifumi Akama

1999-01-01

250

Sorption of Heavy Metal Ions on New Metal-Ligand Complexes Chemically Derived from Lycopodium clavatum  

Microsoft Academic Search

Sorption of heavy metal ions from aqueous solution has been investigated as a function of pH using a novel exchanger system whereby Lycopodium clavatum is functionalized with carboxylate and glyoxime metal-ligand complexes. The new ligand exchangers were prepared using a reaction of diaminosporopollenin with various metal-ligand complexes of glyoxime and monocarboxylic acid. The sorptive behavior of these metal-ligand exchangers and

Erol Pehlivan; Mustafa Ersoz; Salih Yildiz; Harry J. Duncan

1994-01-01

251

Transition Metal Speciation in the Cell: Insights from the Chemistry of Metal Ion Receptors  

NSDL National Science Digital Library

The essential transition metal ions are avidly accumulated by cells, yet they have two faces: They are put to use as required cofactors, but they also can catalyze cytotoxic reactions. Several families of proteins are emerging that control the activity of intracellular metal ions and help confine them to vital roles. These include integral transmembrane transporters, metalloregulatory sensors, and diffusible cytoplasmic metallochaperone proteins that protect and guide metal ions to targets. It is becoming clear that many of these proteins use atypical coordination chemistry to accomplish their unique goals. The different coordination numbers, types of coordinating residues, and solvent accessibilities of these sites are providing insight into the inorganic chemistry of the cytoplasm.

Lydia Finney (Northwestern University;Department of Chemistry, Molecular Biology and Cell Biology); Thomas O'Halleron (Northwestern University;Department of Biochemistry, Molecular Biology and Cell Biology)

2003-05-09

252

Synthesis and structural characterization of amido scorpionate rare earth metals complexes.  

PubMed

The reactivity of hybrid scorpionate/cyclopentadienyl ligands in the form of the protio derivatives as a mixture of two regioisomers, namely bpzcpH [1-{2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl}-1,3-cyclopentadiene and 2-{2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl}-1,3-cyclopentadiene] and bpztcpH [1-{2,2-bis(3,5-dimethylpyrazol-1-yl)-1-tert-butylethyl}-1,3-cyclopentadiene and 2-{2,2-bis(3,5-dimethylpyrazol-1-yl)-1-tert-butylethyl}-1,3-cyclopentadiene], with the tris(silylamide) precursors [M{N(SiHMe2)2}3(thf)x] of rare earth metals (including the group 3 metals scandium and yttrium) is related to the atomic radii of the metal centres. The reaction with the precursor containing the smallest ion, [Sc{N(SiHMe2)2}3(thf)], did not proceed even heating at reflux temperature in toluene. The reaction with the precursors that contain a medium-sized metal ion, i.e., [M{N(SiHMe2)2}3(thf)2] (M = Y, Lu), proceeded only at high temperature and gave good yields of the silylenediamide-containing derivatives [M{?(2)-NN-Me2Si(NSiHMe2)2}(bpzcp)] (M = Y , Lu ) and [M{?(2)-NN-Me2Si(NSiHMe2)2}(bpztcp)] (M = Y , Lu ) by an double activation of Si-H and Si-N bonds. However, the reaction with the precursors that contained the largest metal ions, i.e., [M{N(SiHMe2)2}3(thf)2] (M = Nd, Sm), proceeded rapidly at room temperature to afford the bis(silylamide) complexes [M{N(SiHMe2)2}2(bpzcp)] (M = Nd , Sm ) and [M{N(SiHMe2)2}2(bpztcp)] (M = Nd , Sm ). Additionally, the alkyl heteroscorpionate yttrium and lutetium complexes [M(CH2SiMe3)2(NNCp)] (M = Y, Lu) reacted with an excess of HN(SiHMe2)2 to give the mixed alkyl/amide derivatives [M{N(SiHMe2)2}(CH2SiMe3)(bpzcp)] (M = Y , Lu ) and [M{N(SiHMe2)2}(CH2SiMe3)(bpztcp)] (M = Y , Lu ). The structures of the complexes were determined by spectroscopic methods and the X-ray crystal structures of , and were also established. PMID:24829057

Márquez-Segovia, Isabel; Lara-Sánchez, Agustín; Otero, Antonio; Fernández-Baeza, Juan; Castro-Osma, José Antonio; Sánchez-Barba, Luis F; Rodríguez, Ana M

2014-07-01

253

Therapeutic redistribution of metal ions to treat Alzheimer's disease.  

PubMed

Currently, therapeutics that modify Alzheimer's disease (AD)are not available. Increasing age is the primary risk factor for AD and due to an aging global population the urgent need for effective therapeutics increases every year. This Account presents the development of an AD treatment strategy that incorporates diverse compounds with a common characteristic: the ability to redistribute metal ions within the brain. Central to cognitive decline in AD is the amyloid-? peptide (A?) that accumulates in the AD brain. A range of therapeutic strategies have been developed based on the premise that decreasing the brain A? burden will attenuate the severity of the disease symptoms. Unfortunately these treatments have failed to show any positive outcomes in large-scale clinical trials, raising many questions regarding whether therapeutics for AD can rely solely on decreasing A? levels. An alternate strategy is to target the interaction between A? and metal ions using compounds with the potential to redistribute metal ions within the brain. The original rationale for this strategy came from studies showing that metal ions promote A? toxicity and aggregation. In initial studies using the prototype metal-chelating compound clioquinol (CQ), CQ prevented A? toxicity in vitro, out-competed A? for metal ions without affecting the activity of metal-dependent enzymes, and attenuated the rate of cognitive decline in AD subjects in a small phase II clinical trial. All these outcomes were consistent with the original hypothesized mechanism of action for CQ where prevention or reversal of the extracellular A?-metal interactions could prevent A? toxicity. Soon after the completion of these studies, a new body of work began to suggest that this hypothesized mechanism of action for CQ was simplistic and that other factors were also important for the positive therapeutic outcomes. Perhaps most significantly, it was shown that after CQ sequesters metal ions the neutral CQ-metal complex crosses cell membranes to increase intracellular levels of the metals, thereby initiating protective cell signaling cascades. The activity of CQ therefore appeared to be two-fold: it prevented toxic interactions between A? and metal ions outside the cell, and it redistributed the metal ions into the cell to promote healthy cell function. To determine the significance of redistributing metal ions into the cell, glyoxalbis(N(4)-methylthiosemicarbazonato)Cu(II) [Cu(II)(gtsm)] was tested in models of AD. Cu(II)(gtsm) delivers Cu into cells, but, unlike CQ, it cannot out-compete A? for metal ions. When tested in AD model mice, the Cu(II)(gtsm) treatment restored cognitive function back to levels expected for cognitively healthy mice. The most advanced compound from this therapeutic strategy, PBT2, can sequester metal ions from A? and redistribute them into the cell like CQ. PBT2 improved cognition in a phase II clinical trial with AD patients, and further clinical testing is currently underway. PMID:22747493

Crouch, Peter J; Barnham, Kevin J

2012-09-18

254

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

PubMed Central

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

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

2008-01-01

255

Fluorescent carbon nanoparticles for the fluorescent detection of metal ions.  

PubMed

Fluorescent carbon nanoparticles (F-CNPs) as a new kind of fluorescent nanoparticles, have recently attracted considerable research interest in a wide range of applications due to their low-cost and good biocompatibility. The fluorescent detection of metal ions is one of the most important applications. In this review, we first present the general detection mechanism of F-CNPs for the fluorescent detection of metal ions, including fluorescence turn-off, fluorescence turn-on, fluorescence resonance energy transfer (FRET) and ratiometric response. We then focus on the recent advances of F-CNPs in the fluorescent detection of metal ions, including Hg(2+), Cu(2+), Fe(3+), and other metal ions. Further, we discuss the research trends and future prospects of F-CNPs. We envision that more novel F-CNPs-based nanosensors with more accuracy and robustness will be widely used to assay and remove various metal ions, and there will be more practical applications in coming years. PMID:25058940

Guo, Yongming; Zhang, Lianfeng; Zhang, Shushen; Yang, Yan; Chen, Xihan; Zhang, Mingchao

2015-01-15

256

Highly sensitive colour change system within slight differences in metal ion concentrations based on homo–binuclear complex formation equilibrium for visual threshold detection of trace metal ions  

Microsoft Academic Search

A new technique of expressing slight differences in metal ion concentrations by clear difference in colour was established for visual threshold detection of trace metal ions. The proposed method is based on rapid change of the mole fraction of the homo–binuclear complex (M2L) about a ligand in a narrow range of the total metal ion concentration (MT) in a small

Hitoshi Mizuguchi; Hiroshi Atsumi; Keigo Hashimoto; Yasuhiro Shimada; Yuki Kudo; Masatoshi Endo; Fumihiko Yokota; Junichi Shida; Takao Yotsuyanagi

2004-01-01

257

Metal ion release kinetics from nanoparticle silicone composites.  

PubMed

Metal ion release kinetics from silver and copper nanoparticle silicone composites generated by laser ablation in liquids are investigated. The metal ion transport mechanism is studied by using different model equations and their fit to experimental data. Results indicate that during the first 30 days of immersion, Fickian diffusion is the dominant transport mechanism. After this time period, the oxidation and dissolution of nanoparticles from the bulk determine the ion release. This second mechanism is very slow since the dissolution of the nanoparticle is found to be anisotropic. Silver ion release profile is best described by pseudo-first order exponential equation. Copper ion release profile is best described by a second order exponential equation. For practical purposes, the in vitro release characteristics of the bioactive metal ions are evaluated as a function of nanoparticle loading density, the chemistry and the texture of the silicone. Based on the proposed two-step release model, a prediction of the release characteristics over a time course of 84 days is possible and a long-term ion release could be demonstrated. PMID:21645564

Hahn, Anne; Brandes, Gudrun; Wagener, Philipp; Barcikowski, Stephan

2011-09-01

258

Temperature dependent mobility measurements of alkali earth ions in superfluid helium  

NASA Astrophysics Data System (ADS)

Mobility measurements of impurity ions in superfluid helium are reported. Alkali earth ions were produced with a laser sputtering technique and were drawn inside the liquid by an electric field. The experiments were carried out in the temperature region from 1.27 up to 1.66 K. The temperature dependence of the mobility of Be^+-ions (measured here for the first time) differs from that of the other alkali earth ions Mg^+, Ca^+, Sr^+ and Ba^+, but behaves similar to that of He^+ (M. Foerste, H. Günther, O. Riediger, J. Wiebe, G. zu Putlitz, Z. Phys. B) 104, 317 (1997). Theories of Atkins (A. Atkins, Phys. Rev.) 116, 1339 (1959) and Cole (M.W. Cole, R.A. Bachmann Phys. Rev. B) 15, 1388 (1977) predict a different defect structure for He^+ and the alkali earth ions: the helium ion is assumed to form a snowball like structure whereas for the alkali earth ions a bubble structure is assumed. If the temperature dependence is a characteristic feature for the different structures, then it seems likely that the Be^+ ion builds a snowball like structure.

Putlitz, Gisbert Zu; Baumann, I.; Foerste, M.; Jungmann, K.; Riediger, O.; Tabbert, B.; Wiebe, J.; Zühlke, C.

1998-05-01

259

Observation of sub-kilohertz resonance in Rf-Optical double resonance experiment in rare earth ions in solids  

E-print Network

Observation of sub-kilohertz resonance in Rf-Optical double resonance experiment in rare earth ions-kilohertz resonance structures in RF-optical double resonance experiments of rare-earth-doped solids, when in the course of optical-RF double resonance experiment of rare earth ions in solids. The reso- nance

Shahriar, Selim

260

Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions.  

E-print Network

Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions. C. Mansuy-669" DOI : 10.1016/j.tsf.2005.12.235 #12;Abstract Rare earth doped LuBO3 thin films have been prepared, 81.20. Fw, Keywords : Sol-Gel, Scintillators, XPS, RBS, Rare earth ions, Luminescence hal-00154764

Boyer, Edmond

261

Grid-controlled metal ion sources for heavy ion fusion accelerators  

Microsoft Academic Search

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

L. K. Len; S. Jr. Humphries; C. Burkhart

1986-01-01

262

Low coefficient of thermal expansion polyimides containing metal ion additives  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

263

Rare earth-transition metal alloy permanent magnet materials: 1960–1985  

Microsoft Academic Search

Rare earths, primarily light rare earths, either alone or in combination with other rare earths, as in misch metal, alloyed\\u000a with cobalt or iron, constitute a unique new class of permanent magnet materials with outstanding coercivity and other magnetic\\u000a properties. These materials represent the first serious alternative to the alnicos and ferrites, discovered earlier. The intensity\\u000a of interest in this

E. M. T. Velu; E. C. Subbarao

1986-01-01

264

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

Microsoft Academic Search

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

Masayoshi Nishiura; Zhaomin Hou

2010-01-01

265

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

266

Non-metallocene rare earth metal catalysts for the diastereoselective and enantioselective hydroamination of aminoalkenes  

Microsoft Academic Search

In this short review we summarize our work on new cyclopentadienyl-free rare earth metal catalysts for the diastereoselective and enantioselective hydroamination of aminoalkenes. Non-metallocene rare earth metal catalysts based on diamidoamine, biphenolate and binaphtholate ligands are readily available through alkane and amine elimination procedures. Diamidoamine yttrium complexes are efficient catalysts for the highly diastereoselective cyclization of 1-methyl-pent-4-enylamine to yield trans-2,5-dimethyl-pyrroldine

Kai C. Hultzsch; Denis V. Gribkov; Frank Hampel

2005-01-01

267

Cationic rare earth metal alkyls as novel catalysts for olefin polymerization and copolymerization  

Microsoft Academic Search

Cationic rare earth metal alkyl species, generated by the treatment of mono(cyclopentadienyl) bis(alkyl) rare earth metal complexes with 1 equiv. of a borate compound such as [Ph3C][B(C6F5)4], act as an excellent catalyst for the polymerization and copolymerization of various olefins such as ethylene, 1-hexene, styrene, norbornene, dicyclopentadiene, and isoprene. These catalysts show unprecedented activity and regio- and stereo-selectivity and afford

Zhaomin Hou; Yunjie Luo; Xiaofang Li

2006-01-01

268

Extraction and separation of rare earth metals using microcapsules containing bis(2-ethylhexyl)phosphinic acid  

Microsoft Academic Search

The separation of rare earth metals using microcapsules (MC) consisting styrene (St)–divinylbenzene (DVB) copolymer and containing bis(2-ethylhexyl)phosphinic acid (PIA-226) has been investigated. Microcapsules containing PIA-226 can be prepared by adding PIA-226 to the dispersed phase during the preparation process. The extraction of rare earth metals with the microcapsules progresses via the same scheme, as proposed in the conventional liquid–liquid extraction

Syouhei Nishihama; Nobuya Sakaguchi; Takayuki Hirai; Isao Komasawa

2002-01-01

269

Catalytic asymmetric carbon-carbon bond-forming reaction utilizing rare earth metal complexes  

Microsoft Academic Search

Novel optically active rare earth complexes have made possible a catalytic asymmetric nitroaldol reaction for the first time. Structural elucidation reveals that the complexes consist of one rare earth metal, three lithium atoms, and three BINOL units. Applications of the catalytic asymmetric nitroaldol reaction to syntheses of several p-blockers and erythro-AYA have been also achieved. Although the lithium containing rare

Masakatsu Shibasaki; Hiroaki Sasai

1996-01-01

270

Metal-ion recycle technology for metal electroplating waste waters  

Microsoft Academic Search

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

N. N. Sauer; B. F. Smith

1993-01-01

271

Metal-ion recycle technology for metal electroplating waste waters.  

National Technical Information Service (NTIS)

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 th...

N. N. Sauer, B. F. Smith

1993-01-01

272

Simultaneous multidopant investigation of rare-earth-doped optical fibers by an ion microprobe.  

PubMed

The relative distribution of five elements present in the core area of several optical fiber samples has been obtained by utilizing nanoscale-secondary ion mass spectrometry. A strong correlation between the rare-earth (RE) ion and aluminum was observed, consistent with aluminum's improving the solubility of the RE ion. The central dip in distribution was less severe than that observed for germanium, characteristic of the collapse process during fabrication of the fiber preform. PMID:17072389

Sidiroglou, Fotios; Huntington, Shane T; Roberts, Ann; Stern, Richard; Fletcher, Ian R; Baxter, Greg W

2006-11-15

273

Heavy water reactions with alkaline-earth metal dications in the gas phase  

NASA Astrophysics Data System (ADS)

Room temperature rate coefficients and product distributions are reported for the reactions initiated in D2O with dications of the alkaline-earth metals Mg, Ca, Sr and Ba. The measurements were performed with a selected-ion flow tube (SIFT) tandem mass spectrometer and electrospray ionization (ESI). Mg2+ reacts with water by a fast electron transfer leading to charge separation with a rate coefficient of 1.4 × 10-9 cm3 molecule-1 s-1. Ca2+ reacts with D2O in a first step to form the adduct Ca2+(D2O), with an effective bimolecular rate coefficient of 2.3 × 10-11 cm3 molecule-1 s-1, which then undergoes rapid charge separation by deuteron transfer to form CaOD+ and D3O+ in a second step with k = 7.9 × 10-10 cm3 molecule-1 s-1. The CaOD+ ion reacts further by clustering up to five more D2O molecules. Sr2+ clusters up to eight D2O molecules and Ba2+ up to seven D2O molecules, with the first addition of D2O being rate determining in each case and the last addition being distinctly slower, as might be expected from a transition in the occupation of the added water molecules from an inner to an outer hydration shell.

Feil, Stefan; Koyanagi, Greg K.; Bohme, Diethard K.

2009-02-01

274

A STUDY OF THE RARE-EARTH METAL COMPLEXES  

Microsoft Academic Search

The solid rare-earth chelates of ethylenediaminetetraacetic acid were ; examined using thermobalance, infrared and x-ray-diffraction techniques. The ; lighter members are monohydrates while the heavier members are anhydrous after ; drying for 12 hours at 110 deg C. Infrared studies indicated that the light-; member chelates have a pentadentate EDTA structure while the remaining rare ; earths assume a hexadentate

Kolat

1962-01-01

275

Adsorbent for metal ions and method of making and using  

DOEpatents

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.

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

1999-08-10

276

Adsorbent for metal ions and method of making and using  

DOEpatents

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.

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

2000-01-01

277

Adsorbent for metal ions and method of making and using  

DOEpatents

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.

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

1999-01-01

278

Comet Encke: Meteor metallic ion identification by mass spectrometer  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

279

Mechanism of silica-metal mixing by ion irradiation  

Microsoft Academic Search

The application of ion-beam mixing to the doping of silica films with metals either in solution or in the form of nanoclusters requires a preliminary investigation of the mixing mechanisms. This was undertaken by means of RBS and XRD for Au, Pt, W, Ag and Cu films mixed with silica by 4.5 MeV Au or 200 keV Ar ions, at

J. C. Pivin; P. Colombo

1997-01-01

280

Broad-beam multi-ampere metal ion source  

SciTech Connect

An embodiment of the MEVVA (metal vapor vacuum arc) high current metal ion source has been developed in which the beam is formed from a 10-cm-diam set of extractor grids and which produces a peak beam current of up to several amperes. The source, MEVVA V, operates in a pulsed mode with a pulsewidth, at present, of 0.25 ms and a repetition rate of up to several tens of pulses per second (power supply limited). The multi-cathode feature that was developed for the prior source version, MEVVA IV, has been incorporated here also; one can switch among any of 18 separate cathodes and thus metallic beam species. Maximum beam extraction voltage is over 90 kV, and since the ion charge states are typically from {ital Q}=1 to 5, depending on the metal employed, the ion energy in the extracted beam can thus be up to several hundred keV. This source is a new addition to the MEVVA family of metal ion sources, and we are at present investigating the operational regimes and the limits to the source performance. In this article we describe the source, and present some preliminary results.

Brown, I.G.; Galvin, J.E.; MacGill, R.A. (Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (US)); Paoloni, F.J. (Electrical Engineering Department, University of Wollongong, Wollongong NSW 2500, (Australia))

1990-01-01

281

Broad-beam multi-ampere metal ion source  

SciTech Connect

An embodiment of the MEVVA (metal vapor vacuum arc) high current metal ion source has been developed in which the beam is formed from a 10-cm diameter set of extractor grids and which produces a peak beam current of up to several Amperes. The source, MEVVA V, operates in a pulsed mode with a pulse width at present 0.25 ms and a repetition rate of up to several tens of pulses per second (power supply limited). The multicathode feature that was developed for the prior source version, MEVVA IV, has been incorporated here also; one can switch between any of 18 separate cathodes and thus metallic beam species. Maximum beam extraction voltage is over 90 kV, and since the ion charge state typically from Q = 1 to 5, depending on the metal employed, the ion energy in the extracted beam can thus be up to several hundred keV. This source is a new addition to the MEVVA family of metal ion sources, and we are at present investigating the operational regimes and the limits to the source performance. In this paper we describe the source and present some preliminary results. 10 refs., 4 figs.

Brown, I.G.; Galvin, J.E.; MacGill, R.A.; Paoloni, F.J. (Lawrence Berkeley Lab., CA (USA); Wollongong Univ. (Australia). Dept. of Electrical Engineering)

1989-06-01

282

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

SciTech Connect

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

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

1994-08-01

283

Improved scales for metal ion softness and toxicity.  

PubMed

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

Kinraide, Thomas B

2009-03-01

284

Metal-Ion Additives Reduce Thermal Expansion Of Polyimides  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

285

Interaction of copper metallization with rare-earth metals and silicides  

SciTech Connect

Solid-phase reactions of copper films with underlying gadolinium, erbium, and erbium{endash}silicide layers on Si(100) substrates were investigated. For the phase analysis, x-ray diffraction and cross-sectional transmission electron microscopy were used. In the case of Cu/Gd/Si(100), an orthorhombic GdSi{sub 2} formed, and, at higher temperatures, copper aggregated into islands. Annealed Cu/Er/Si(100) samples resulted in a hexagonal Er{sub 5}Si{sub 3} phase. In the Cu/ErSi{sub 2{minus}x}/Si system, the copper catalyzes the transformation of the highly oriented hexagonal ErSi{sub 2{minus}x} phase into hexagonal Er{sub 5}Si{sub 3}. Diverse phase developments of the samples with Gd and Er are based on reactivity differences of the two rare-earth metals. {copyright} 2001 American Institute of Physics.

Molnar, G. L.; Peto, G.; Zsoldos, E.; Horvath, Z. E.

2001-07-01

286

Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps  

NASA Astrophysics Data System (ADS)

A newly constructed apparatus at the United States 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 trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.

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

287

Soda-fuel metallurgy: Metal ions for carbon neutral CO2 and H2O reduction  

NASA Astrophysics Data System (ADS)

The role of minerals in biomass formation is understood only to a limited extent. When the term “photosynthesis—CO2 and H2O reduction of sugars, using solar energy”—is used, one normally thinks of chlorophyll as a compound containing magnesium. Alkali and alkaline earth metals present in leaf cells in the form of ions are equally essential in this solar energy bioconversion coupled with nitrogen fixation. Application of some of these principles can lead to artificial carbon-neutral processes on an industrial scale close to the concentrated CO2 emission sources.

Neelameggham, Neale R.

2009-04-01

288

The chemistry of meteoric metals in the Earth's upper atmosphere  

Microsoft Academic Search

The presence of thin layers of free metal atoms at around 90 km in the upper atmosphere has been known for about fifty years. Layers of the alkali metals Na, K and Li, as well as Ca and Fe, have been observed. This discovery has posed two important questions. First, what is the source of the metals: interplanetary or terrestrial?

John M. C. Plane

1991-01-01

289

Sensing Metal Ions with DNA Building Blocks: Fluorescent Pyridobenzimidazole Nucleosides  

PubMed Central

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

Kim, Su Jeong; Kool, Eric T.

2008-01-01

290

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

SciTech Connect

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

Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S. [Corporate Research and Development Center, Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba-shi, Ibaraki-ken 305-8568 (Japan)

2006-07-31

291

Uptake of Metal Ions by Rhizopus arrhizus Biomass  

PubMed Central

Rhizopus arrhizus biomass was found to absorb a variety of different metal cations and anions but did not absorb alkali metal ions. The amount of uptake of the cations was directly related to ionic radii of La3+, Mn2+, Cu2+, Zn2+, Cd2+, Ba2+, Hg2+, Pb2+, UO22+, and Ag+. The uptake of all the cations is consistent with absorption of the metals by sites in the biomass containing phosphate, carboxylate, and other functional groups. The uptake of the molybdate and vanadate anions was strongly pH dependent, and it is proposed that the uptake mechanism involves electrostatic attraction to positively charged functional groups. PMID:16346521

Tobin, J. M.; Cooper, D. G.; Neufeld, R. J.

1984-01-01

292

Metal ion bombardment of onion skin cell wall  

SciTech Connect

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.

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

2004-05-10

293

MAGNETIC ORDERING AND THE ELECTRONIC STRUCTURE OF RARE-EARTH METALS  

Microsoft Academic Search

The effects of magnetic ordering of the localized 4f electrons in rare ; earth metals on the structure of the Brillouin zones in these metals, and hence ; on the conduction-electron characteristics, are studied by means of a ; magneticsuperlattice model. The model takes into account the exchange ; interaction between the 4f and conduction electrons, and effects of spin-orbit

A. Mackintosh

1962-01-01

294

Extraction of rare-earth metals by liquid surfactant membranes containing a novel cyclic carrier  

Microsoft Academic Search

Extraction behavior of three rare-earth metals (Ho, Er and Y), was systematically studied by liquid surfactant membranes (LSMs) containing a novel host compound, a calixarene carboxyl derivative, which is a cyclic compound connected to some phenol rings, as a mobile carrier in a stirred cell. Using the host compound, the extraction equilibrium of the metals in liquid-liquid extraction was also

Takahiko Kakoi; Takayuki Nishiyori; Tatsuya Oshima; Fukiko Kubota; Masahiro Goto; Seiji Shinkai; Fumiyuki Nakashio

1997-01-01

295

Mutual influence of elements during coprecipitation. Cocrystallization of rare-earth elements under conditions for the formation of double sulfates of alkali and alkaline-earth metals  

Microsoft Academic Search

This paper studies the coprecipitation of rare-earth metals under conditions for the crystallization of double salts in other sulfate systems, as well as the possibility of the employment of these double salts for the selective preconcentration of rare-earth metals from solutions of complex composition. The influence of electrolytes containing and not containing an element which may act as a charge

G. I. Tsizin; N. B. Kalinchenko; G. I. Malofeeva; I. N. Marov; K. I. Tobelko; V. S. Urusov

1985-01-01

296

Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete  

DOEpatents

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.

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

1985-01-01

297

Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete  

DOEpatents

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.

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

1981-11-04

298

Selective titrations of metal ions in the micromolar range  

Microsoft Academic Search

Summary An outline is given of the factors governing the complexometric titration of metal ions at low concentration. Apart from the limit of determination, special attention has been given to the selectivity of the determinations. The influence of the chemical reaction and of the method of indication has been discussed.

G. den Boef

1978-01-01

299

Modeling Substorm Ion Injection in the Near-Earth Magnetotail  

Microsoft Academic Search

On March 23, 2007 the THEMIS satellite constellation provided us with a unique opportunity to study substorm injection in the region beyond geosynchronous orbit. On March 23 all five THEMIS spacecraft observed substorm injection in the near earth tail (X~-7RE). We have used the THEMIS observations to examine magnetic field dipolarization and plasma bulk flow. We have carried out large

M. Zhou; M. Ashour-Abdalla; X. Deng; M. El-Alaoui; R. L. Richard; R. J. Walker; V. Peroomian; V. Angelopoulos

2008-01-01

300

Broad-beam, high current, metal ion implantation facility  

SciTech Connect

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.

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

1990-07-01

301

Correlation between volatility of rare-earth metals and encapsulation of their carbides in carbon nanocapsules  

SciTech Connect

Encapsulation of metals in multilayered graphitic capsules has been studied for all the rare-earth elements (Sc, Y, and Ln = La, Ce, ..., Lu) excluding Pm by using electric arc discharge. Electron microscopy and X-ray diffraction of carbonaceous products revealed that most of rare-earth metals (Sc, Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu) were encapsulated in the form of carbides, but the others, Sm, Eu, and Yb, were not. The metals in the former group that were encapsulated had vapor pressures definitely lower than those in the latter group. In the case of thulium (Tm), whose vapor pressure is intermediate between the two groups, only a trace amount of encapsulated carbide was formed. Correlation of volatility of metals with encapsulation was clearly found, suggesting that the volatility of a metal plays an important role in a process of the metal encapsulation. 25 refs., 4 figs., 1 tab.

Saito, Yahachi; Okuda, Mitsumasa; Yoshikawa, Tadanobu (Mie Univ., Tsu (Japan)); Kasuya, Atsuo; Nishina, Yuichiro (Tohoku Univ., Sendai (Japan))

1994-07-07

302

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

303

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

SciTech Connect

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.

Nicholas B. Lentz

2007-12-01

304

Method for removing metal ions from solution with titanate sorbents  

DOEpatents

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.

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

1999-01-01

305

Rigid versus flexible: how important is ligand "preorganization" for metal ion recognition by lower rim-functionalized calix[4]arenes?  

PubMed

For an assessment of the outcomes from use of an appropriately "preorganized" calixarene-based ionophore versus its conformationally mobile prototype, solvent extraction propensities of flexible calix[4]arene di-[N-(X-sulfonyl)carboxamides] for alkali, alkaline earth metal cations, Pb2+, Ag+ and Hg2+ are compared with those for seven new rigid analogs fixed in the cone, partial cone and 1,3-alternate conformations. For each of the metal ions, the preferred calix[4]arene conformation was determined from the NMR spectra for the metal salt of the flexible ligand. Except for Ag+, flexible calix[4]arene di-[N-(X-sulfonyl)carboxamides] were found to provide greater metal ion extraction efficiency and better selectivity than the corresponding "preorganized" ionophores. PMID:15351822

Talanova, Galina G; Talanov, Vladimir S; Hwang, Hong-Sik; Park, Chunkyung; Surowiec, Kazimierz; Bartsch, Richard A

2004-09-21

306

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

307

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

SciTech Connect

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.

Talbayev, Diyar [Los Alamos National Laboratory; Trugman, Stuart A [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory; Averitt, Richard D [Los Alamos National Laboratory; Namjung, Hur [INHA UNIV; Andrew, Laforge D [UCSD; Dimitri, Basov N [UCSD

2008-01-01

308

Chitosan removes toxic heavy metal ions from cigarette mainstream smoke  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

309

Novel luminescent hybrids by incorporating rare earth ?-diketonates into polymers through ion pairing with an imidazolium counter ion.  

PubMed

A series of luminescent polymers are synthesized by incorporating rare earth complex units into polymer matrices. Firstly, we functionalize the selected polymer matrices with the imidazolium moieties, and then introduce the rare earth tetrakis(?-diketonate) complexes into polymer matrices through a mild anion exchange method. The resulting materials are characterized by FTIR, XRD, EDAX, SEM, thermogravimetric analysis, luminescence excitation spectra and emission spectra, luminescence lifetime measurements and diffuse reflectance UV-Vis spectra. The photoluminescence measurements indicate that all these rare earth complex functionalized polymers exhibit a characteristic luminescence emission originating from the corresponding rare earth ions. Among the hybrids, the europium tetrakis(TTA) complex functionalized polymers show remarkable luminescence quantum yields and relatively long (5)D0 lifetimes at room temperature. PMID:23719771

Li, Qiu-Ping; Yan, Bing

2013-09-01

310

Measurements of positive ions and air-earth current density at Maitri, Antarctica  

E-print Network

Simultaneous measurements of the small-, intermediate- and large- positive ions and air earth current density made at a coastal station, Maitri at Antarctica during January to February 2005, are reported. Although, small and large positive ion concentrations do not show any systematic diurnal variations, variations in them are almost similar to each other. On the other hand, variations in intermediate positive ion concentrations are independent of variations in the small/large positive ions and exhibit a diurnal variation which is similar to that in atmospheric temperature on fair weather days with a maximum during the day and minimum during the night hours. No such diurnal variation in intermediate positive ion concentration is observed on cloudy days when variations in them are also similar to those insmall/large positive ion concentrations. Magnitude of diurnal variation in intermediate positive ion concentration on fair weather days increases with the lowering of atmospheric temperature in this season. Sc...

Siingh, Devendraa; Kamra, A K; 10.1029/2006JD008101

2009-01-01

311

Solution NMR refinement of a metal ion bound protein using metal ion inclusive restrained molecular dynamics methods.  

PubMed

Correctly calculating the structure of metal coordination sites in a protein during the process of nuclear magnetic resonance (NMR) structure determination and refinement continues to be a challenging task. In this study, we present an accurate and convenient means by which to include metal ions in the NMR structure determination process using molecular dynamics (MD) simulations constrained by NMR-derived data to obtain a realistic and physically viable description of the metal binding site(s). This method provides the framework to accurately portray the metal ions and its binding residues in a pseudo-bond or dummy-cation like approach, and is validated by quantum mechanical/molecular mechanical (QM/MM) MD calculations constrained by NMR-derived data. To illustrate this approach, we refine the zinc coordination complex structure of the zinc sensing transcriptional repressor protein Staphylococcus aureus CzrA, generating over 130 ns of MD and QM/MM MD NMR-data compliant sampling. In addition to refining the first coordination shell structure of the Zn(II) ion, this protocol benefits from being performed in a periodically replicated solvation environment including long-range electrostatics. We determine that unrestrained (not based on NMR data) MD simulations correlated to the NMR data in a time-averaged ensemble. The accurate solution structure ensemble of the metal-bound protein accurately describes the role of conformational sampling in allosteric regulation of DNA binding by zinc and serves to validate our previous unrestrained MD simulations of CzrA. This methodology has potentially broad applicability in the structure determination of metal ion bound proteins, protein folding and metal template protein-design studies. PMID:23609042

Chakravorty, Dhruva K; Wang, Bing; Lee, Chul Won; Guerra, Alfredo J; Giedroc, David P; Merz, Kenneth M

2013-06-01

312

The ligand-promoted mobilisation of metal ions from mineral surfaces  

NASA Astrophysics Data System (ADS)

Many metals such as Fe, Mo, Cu, Zn etc have been identified as essential micronutrients for plants and microorganisms. These metals have to be mobilised from mineral surfaces in contact with crustal fluids in order to be available to living cells. Many studies have shown the importance of chelation in the mobilisation of metal ions into these fluids. The ligand-promoted dissolution of minerals enables elements essential to life to be accessible. Organic acids with chelating properties are widely present on the surface of the earth (both anthropogenic and those produced naturally such as siderophores) and as well as releasing metal ions into solution for bioavailability, they control processes such as metal ion transport and adsorption and thereby are important in the understanding of toxicity and contamination. In this study we have compared mineral dissolution using a strong industrial chelator (DTPA -- diethylene triamine penta-acetic acid) and dissoluton using a synthetically produced naturally occurring siderophore, 2,3-dihydroxybenzoic acid produced by Azotobacter vinelandii. The dissolution kinetics of a number of minerals (barite, chalcopyrite, malachite) by DTPA solution has been studied as a function of DTPA concentration in the range 0.001--0.5 M. Batch experiments were carried out at pH 12 where the DTPA is effectively de-protonated and over a range of temperatures (22--90C^o) to investigate the factors controlling the dissolution rate.. Although the dissolution mechanism involves the chelation of one metal ion by each molecule of DTPA, the dissolution rate was found to be inversely related to the DTPA concentration in solution and not dependent on the initial grain size of the mineral. The high activation energy for the dissolution process suggests that the rate is controlled by a surface desorption process rather than diffusion in the solution. The inverse dependence on the DTPA concentration suggests steric hindrance associated with the metal-DTPA surface complex formation. Dissolution kinetics of the natural siderophore, known to be specfic to Fe chelation, was observed under similar conditions and comparisons made with the strong industrial chelator in an attempt to understand the dissolution process. The results have important applications to many aspects of mineral dissolution and therefore metal ion mobility as well as raising fundamental questions regarding the nature of the crystal-solution interface at an atomic level.

Putnis, C. V.

2003-04-01

313

Trivalent rare-earth ions as photon down-shifter for photovoltaic applications  

NASA Astrophysics Data System (ADS)

Rare-earth doped borate glasses are investigated for their potential as photon down-shifting cover glass for CdTe solar cells. Note, that CdTe solar cells have a poor response in the ultraviolet and blue spectral range due to absorption in the CdS buffer layer having a band gap of 2.4 eV. The following trivalent rare-earth ions are analyzed in detail: Sm3+, Eu3+, and Tb3+. These ions provide strong absorption bands in the ultraviolet / blue spectral range and an intense emission in the red (Sm3+ and Eu3+) or green (Tb3+) spectral range. The gain in short-circuit current density of a CdTe solar cell is calculated for different rare-earth ion concentrations. The calculations are based on the rare-earth's absorption coefficients as well as their photoluminescence (PL) quantum efficiency. For Sm3+, the PL quantum efficiency depends significantly on the doping concentration. Finally, the potential of double-doped borate glasses, i.e. glasses doped with two different rare-earth ions, is investigated.

Steudel, Franziska; Loos, Sebastian; Ahrens, Bernd; Schweizer, Stefan

2014-05-01

314

JOURNAL DE PHYSIQUE Colloque C6, suppliment au no 12, Tome 37, Dtcembre 1976, page C6-639 HYPERFINE INTERACTIONS OF RARE EARTH IONS SUBSTITUTIONAL1,Y  

E-print Network

INTERACTIONS OF RARE EARTH IONS SUBSTITUTIONAL1,Y IMPLANTED IN IRON AND NICKEL L. NIESEN and H. P. WIT (8.4 keV) has been used to study the hyperfine interaction of the fraction of rare earth ions crystalline electric field for a rare earth ion in a ferromagnetic host. Mossbauer spectroscopy on rare earth

Paris-Sud XI, Université de

315

Status of the MEVVA (Metal Vapor Vacuum Arc) high current metal ion source. [Metal Vapor Vacuum Arc  

SciTech Connect

The MEVVA (Metal Vapor Vacuum Arc) ion source that has been developed at LBL was reported on for the first time at the 1985 Particle Accelerator Conference (1). This source can produce hundreds of milliamperes of beam current of metal species from lithium up to uranium. In the period since then we have developed the source further, and this work is summarized here. We have now run the source with over 30 different beam species, and with an extraction voltage up to 110 kV. We have made and operated a miniature source, the MicroMEVVA. A multi-cathode version, in which one can switch rapidly between cathodes of different materials, has recently been constructed and tested. Applications of the source include: as a synchrotron ion source, as an ion source for heavy ion fusion, and for metallurgical ion implantation; we have done some preliminary work in these directions.

Brown, I.G.; Galvin, J.E.; MacGill, R.A.; Wright, R.T.

1987-03-01

316

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

317

Metal content of metallo-?-lactamase L1 is determined by the bioavailability of metal ions†  

PubMed Central

In an effort to probe whether the metal content of metallo-?-lactamase L1 is affected by metal ion bioavailability, L1 was over-expressed as mature protein (M-L1) and full-length (FL-L1) analogs, and the analogs were characterized with metal analyses, kinetics, and EPR spectroscopy. FL-L1, containing the putative leader sequence, was localized in the periplasm of E. coli and shown to bind Zn(II) preferentially. The metal content of FL-L1 could be altered if the enzyme was over-expressed in minimal medium containing Fe and Mn, and surprisingly, an Fe-binding analog was obtained. On the other hand, M-L1, lacking the putative leader sequence, was localized in the cytoplasm of E. coli and shown to bind various amounts of Fe and Zn(II), and like FL-L1, the metal content of the resulting enzyme could be affected by the amount of metal ions in the growth medium. L1 was refolded in the presence of Fe, and a dinuclear Fe-containing analog of L1 was obtained, although this analog is catalytically-inactive. EPR spectra demonstrate the presence of an antiferromagnetically-coupled Fe(III)Fe(II) center in Fe-containing L1 and suggests the presence of a Fe(III)Zn(II) center in M-L1. Metal analyses on the cytoplasmic and periplasmic fractions of E. coli showed that the concentration of metal ions in the periplasm is not tightly controlled and increases as the concentration of metal ions in the growth medium increases. In contrast, the concentration of Zn(II) in the cytoplasm is tightly-controlled while that of Fe is less so. PMID:18597493

Hu, Zhenxin; Gunasekera, Thusitha S; Spadafora, Lauren; Bennett, Brian; Crowder, Michael W.

2009-01-01

318

Determination of uranium and rare-earth metals separation coefficients in LiCl KCl melt by electrochemical transient techniques  

NASA Astrophysics Data System (ADS)

The main step in the pyrometallurgical process of spent nuclear fuel recycling is a molten salt electrorefining. The knowledge of separation coefficients of actinides (U, Np, Pu and Am) and rare-earth metals (Y, La, Ce, Nd and Gd) is very important for this step. Usually the separation coefficients are evaluated from the formal standard potentials of metals in melts containing their own ions, values obtained by potentiometric method. Electrochemical experiments were carried out at 723-823 K in order to estimate separation coefficients in LiCl-KCl eutectic melt containing uranium and lanthanum trichlorides. It was shown that for the calculation of uranium and lanthanum separation coefficients it is necessary to determine the voltammetric peak potentials of U(III) and La(III), their concentration in the melt and the kinetic parameters relating to U(III) discharge such as transfer and diffusion coefficients, and standard rate constants of charge transfer.

Kuznetsov, S. A.; Hayashi, H.; Minato, K.; Gaune-Escard, M.

2005-09-01

319

The influence of transition metal ions on collagen mineralization.  

PubMed

The ions in body fluid play an important role in bone formation besides being a synthesizing material. Transition metal ions Co(2+), Ni(2+), Zn(2+), Fe(3+), Mn(2+), Cu(2+), Cd(2+) and Hg(2+) doped hydroxyapatite (HAP)/collagen composites were synthesized successfully in the presence of collagen traces at mild acidic pH for the first time. However, the amount of doped Hg(2+) and Cd(2+) was relatively low. Meanwhile, through soaking the collagen sponge as a template in simulated body fluid (SBF) which contains different transition metal ions (Mn(2+), Cu(2+), Ni(2+), Co(2+), Cd(2+), Hg(2+)), bone-like HAP/collagen composites were synthesized. Hg(2+) had a certain inhibitory effect on the formation of HAP crystals on the surface of the collagen sponge while Co(2+) can promote the formation of HAP on the collagen sponge. For both HAP/collagen composites and HAP/collagen sponge, it was found that transition metal ions Mn(2+) had a significant effect on the morphology of HAP particles and could induce to form floc-like HAP particle aggregates. PMID:23498275

Jia, Mingfen; Hong, Yuanping; Duan, Shuyuan; Liu, Yongjun; Yuan, Bo; Jiang, Fengzhi

2013-05-01

320

Peptide immobilisation on porous silicon surface for metal ions detection.  

PubMed

In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization.The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution. PMID:21711937

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

2011-01-01

321

Multiply stripped ion generation in the metal vapor vacuum arc  

SciTech Connect

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.

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

1987-09-01

322

Long-lived artificial ion clouds in the earth's ionosphere  

NASA Technical Reports Server (NTRS)

In two barium releases made over the Caribbean during the summer of 1991, the ion cloud was observed to last more than 10 hours. Observations were made with a low light level TV imager and a TV spectrograph operated onboard a Russian research vessel conducting ionospheric research and participating in the NASA-CRRES mission. The two clouds were observed near the release region for 15 to 25 minutes during the twilight following the initial release. One of the releases was made during evening twilight and the ion cloud reappeared the following morning, while the other was a morning release and the late-time observations made the next evening. The observations are highly surprising since, generally, it has been assumed that the ion cloud would dissipate within a few hours. However, the long life time appears consistent with current knowledge about dissipative processes. The long lifetime of barium ion clouds may provide for the most sensitive experimental testing of ionospheric convection models, a possibility with clear implications for future barium release experiments.

Milinevskij, G. P.; Kashirin, A. I.; Romanovskij, Yu. A.; Stenbaek-Nielsen, H. C.; Kelley, M. C.

1993-01-01

323

New Catalytic DNA Biosensors for Radionuclides and Metal ion  

SciTech Connect

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.

Yi Lu

2008-03-01

324

Reactive Ion Etching of Transition-Metal Alloys  

NASA Astrophysics Data System (ADS)

For production of advanced spin-electronic devices, such as a magnetic random access memory with the higher-density memory cell, a reactive ion etching (RIE) process of transition metal alloys is the indispensable component of development, while no transition-metal compounds with the relatively high vapor pressure have been founded so far. Here, we show the RIE process of a NiFe thin film by using CH4:O2:NH3 discharge. The RIE process was designed by ab initio calculations, and the present result is the first successful demonstration of the chemical effect in the RIE process for transition-metal alloys. The relative etching ratio of NiFe against Ti as the metal mask was decreased by substituting CH4 with CHF3.

Akinaga, Hiro; Takano, Fumiyoshi; Matsumoto, Shigeno; Diño, Wilson A. T.

325

New Permanent Magnet Materials Containing Rare-Earth Metals  

Microsoft Academic Search

Previously, most basic magnetic properties of the hexagonal intermetallic compounds involving the rare-earth (RE) and 3-d transition elements were reported in the literature. In addition, some of these compounds were investigated by various workers for permanent magnet properties by grinding ingots of the compounds into very fine powder. Recently, we discovered new permanent magnet materials which were based mostly on

E. A. Nesbitt

1969-01-01

326

Luminescence of rare-earth ions in perovskite-type oxides: from basic research to applications  

Microsoft Academic Search

Luminescence of a rare-earth ion in SrTiO3 or other perovskite-type oxides was used as a probe of physical properties of a host crystal, but not as a phosphor because observed luminescence efficiency was low. Recent investigations have shown that the luminescence efficiency of SrTiO3:Pr3+ is intensified up to 200 times by addition of Al ions. This paper reviews experimental results

Haijme Yamamoto; Shinji Okamoto; Hiroshi Kobayashi

2002-01-01

327

Magnetic field orientation and suprathermal ion streams in the earth's foreshock  

Microsoft Academic Search

The different populations of backstreaming ions found earlier with ISEE instruments outside the earth's bow shock were organized by the orientation of the IMF to the shock in the plane containing B\\/sub SW\\/ and the solar ecliptic X axis (the B-X plane). The associations of ion classes with field geometry and shock structure are shown by means of computer-drawn three-dimensional

E. W. Greenstadt; C.T. Russell; M. Hoppe

1980-01-01

328

Effect on uptake of heavy metal ions by phosphate grafting of allophane.  

PubMed

The effect of phosphate grafting on the uptake of various heavy metal ions was investigated using allophane, a clay mineral having a chemical composition of 1-2SiO2Al2O3.5-6H2O with hollow nanoparticles 3.5-5 nm in size. Phosphate grafting was performed on allophane with an atomic ratio Si/Al=0.85 using the orthophosphates (NH4)2HPO4, Na2HPO4 and CaHPO4 and the triphosphate Na5P3O10. The cations in the phosphates were partially retained in the samples, along with the grafted phosphate. Uptake experiments were performed with various heavy metal ions (Cu2+, Zn2+, Ni2+, Co2+, and Mn2+) and alkaline earth ions (Mg2+ and Ca2+) using a batch method. With increasing amounts of grafted phosphate, the Cu2+ uptake capacity increases to about double of that of ungrafted allophane. Although part of the grafted phosphate is released during the uptake experiments, this can be largely suppressed by heat-treating the samples at 200-500 degrees C. The Cu2+ uptake ability of the (NH4)2HPO4-grafted sample showed a steep decrease with higher heating temperature according to the thermal decomposition of NH4+. The ratios of cations released from the samples to cations removed from solution (2Na/Cu and Ca/Cu) are close to unity. From these results, the replacement reaction is thought to be the main uptake mechanism of heavy metal ions in the present samples. The uptake abilities of the present samples for various cations are explained with respect to the solubilities of the corresponding metal phosphates. PMID:15897056

Okada, Kiyoshi; Nishimuta, Koji; Kameshima, Yoshikazu; Nakajima, Akira

2005-06-15

329

Polymer filtration systems for dilute metal ion recovery  

SciTech Connect

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.

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

1998-12-01

330

Silica gel modified with Eriochrome Blue SE as a sorbent in trace analysis for metal ions  

Microsoft Academic Search

The sorption of 14 metal ions on silica gel impregnated with a mixture of Aliquat 336 and Eriochrome Blue SE was investigated. It was found that the sorption behaviour depends upon the species and the pH of the loading solution. Alkali metal ions were not retained under any of the investigated conditions. The retained metal ions can be eluted with

Ryszard Kocjan; Ryszard ?wieboda

1996-01-01

331

Structurally colored biopolymer thin films for detection of dissolved metal ions in aqueous solution  

Microsoft Academic Search

Natural polymers, such as the polysaccharides alginate and chitosan, are noted sorbents of heavy metals. Their polymer backbone structures are rich in ligands that can interact with metal ions through chelation, electrostatics, ion exchange and nonspecific mechanisms. These water-soluble biopolymer materials can be processed into hydrogel thin films, creating high surface area interfaces ideal for binding and sequestering metal ions

Matthew David Cathell

2008-01-01

332

Kinetic and mechanistic aspects of metal ion catalysis in cerium(IV) oxidation  

Microsoft Academic Search

This review discusses the kinetic aspects of different metal ion catalysis in Ce(IV) oxidation of different types of organic and inorganic substrates in aqueous acid media. The reactions have been categorised with the metal ions acting as the catalysts. The nature of mechanism of catalysis in Ce(IV) oxidation depends on the nature of substrate for a particular metal ion catalyst

Asim K. Das

2001-01-01

333

Ions upstream of the earth's bow shock - A theoretical comparison of alternative source populations  

NASA Technical Reports Server (NTRS)

The trajectories of ions reflected or leaked upstream from the earth's bow shock and subject solely to the Lorentz force in a steady interplanetary magnetic field B and the V x B electric field are studied theoretically. Expressions are obtained for the guiding center motion and gyromotion in a frame (the Hoffman-Teller frame) moving parallel to the shock surface with sufficient speed to transform the incident solar wind velocity into motion entirely along the interplanetary magnetic field. Equations are derived which transform these motions back to the observer's frame. The predicted upstream motions for four different source models for upstream ions are compared using these expressions: magnetic moment-conserving reflection of solar wind ions, specular reflection of solar wind ions, magnetic moment-conserving leakage of magnetosheath ions, and leakage of magnetosheath ions parallel to the shock normal.

Schwartz, S. J.; Thomsen, M. F.; Gosling, J. T.

1983-01-01

334

Liquid metal batteries : ambipolar electrolysis and alkaline earth electroalloying cells  

E-print Network

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 ...

Bradwell, David (David Johnathon)

2011-01-01

335

Metal fluoride coatings prepared by ion-assisted deposition  

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

336

Engineering rare-earth-doped heavy metal oxide glasses for 2-5 ?m lasers  

NASA Astrophysics Data System (ADS)

The electronic states in trivalent rare-earth ions offer an excellent opportunity for designing efficient fibre and bulk lasers for atmospheric remote sensing and LIDAR technology. The first part of this review article focuses on engineering passive fibres for 2-5 ?m transmission. The fabrication of single-mode tungsten tellurite optical fibres from high purity bulk glass rods is described. Fibres with a numerical aperture of 0.1 and core diameter of 10+/-2 ?m have been drawn using suction and rod-in-tube techniques of fibre preform fabrication. Losses of 2.3 dBm-1 at 974 nm have been measured. These fibres are of interest for use as passive transmission fibre or active fibres for lasing in the 2-5 ?m spectral region. The use of heavy metal oxides in the fabrication of glass leads to extended infrared transmission. In the 2nd part of the review we compare the slope efficiencies of Tm3+ and Tm3+/Ho3+ doped glasses and fibres for 1950-2080 nm lasers using a range of pumping schemes in tellurite and germanium oxide hosts. We also explain the importance of choosing 1950-2080 nm tunable lasers as a pump source for stimulated emission at longer wavelengths.

Richards, Billy D. O.; Jha, Animesh; Dorofeev, Vitaly; Manzur, Tariq

2010-04-01

337

Laser diode stabilisation for coherent driving of rare earth ions  

NASA Astrophysics Data System (ADS)

We report on the frequency stabilisation of an extended cavity diode laser for the coherent driving of thulium ions. This stabilisation loop uses a single locking point on an intra-cavity electro-optic crystal. It uses neither the diode current, nor any piezoelectric actuator, making its conception simple, versatile, and independent of the diode itself. Thanks to this, the laser linewidth with respect to the reference cavity is reduced well below 1 kHz. The laser coherence time is then much longer than the atomic coherence lifetime of the thulium ions. The performances of this stabilised source are used in basic coherent driving experiments in a Tm 3+:YAG crystal. Efficient inversion of population by single adiabatic transfer and creation of narrow absorption lines by repetitive excitations are achieved.

Crozatier, V.; Seze, F. de; Haals, L.; Bretenaker, F.; Lorgeré, I.; Gouët, J.-L. Le

2004-11-01

338

Metal ion leaching from contaminated soils: Model development  

SciTech Connect

A mathematical model is developed for metal leaching from contaminated soils subjected to acid extraction in a batch reactor. The model considers transport by pore diffusion and film transfer, leaching of metal bound to reversible and irreversible phases, and metal complexation by ions in solution. As currently developed, the model is semiempirical, with the primary objective of exploring the relative significance of chemical kinetics and diffusional transport under acidic leaching conditions. Simulation results and sensitivity analyses show that leaching kinetics vary according to the metal binding mechanism and location with a soil particle. The effects of pH, pore diffusion, film transfer, chemical reaction rate, particle size, and initial metal distribution are examined using parameter estimates derived from experimental data for a hazardous-waste-site soil contaminated with lead. Depending on leaching conditions, diffusion, reaction, or both may control metal leaching for time-scales of interest in soil washing. Both the distribution of contaminant metal between the reversibly and irreversibly sorbed fractions and the initial spatial distribution within the soil particle are important in determining leaching behavior.

Ganguly, C.; Rabideau, A.J.; Benschoten, J.E. Van [Univ. of New York, Buffalo, NY (United States). Dept. of Civil Engineering; Matsumoto, M.R. [Univ. of California, Riverside, CA (United States). College of Engineering

1998-03-01

339

Stability constants of HBED with various metal ions  

E-print Network

. A combination of potentiometric titration and spectrophotometric titration at varying high -log[H]'s was used to determine the protonation constants for HBED. Potentiometric titrations of 1:1 metal:HBED solutions were used to obtain stability... The importance for the determination of the stability constants for the ligand N, N'-bis(2-hydroxybenzyl)? ethylenediamine-N, N'-diacetic acid (HBED) with various metal ions is that it has the potential to form highly stable complexes with ~ BGa(III) In...

Long, Gregory Neal

2012-06-07

340

THE HEATS OF FUSION AND TRANSITION OF ALKALINE EARTH AND RARE EARTH METAL HALIDES  

Microsoft Academic Search

The heats of fusion of fifteen rare earth and alkaline earth halides ; were measured by means of a copper block drop calorimeter. The salts and their ; heats of fusion in kcal mole⁻¹ are LaClâ, 13.0; PrClâ, 12.1; ; NdClâ, 12.0; C eIâ, 12.4; PrIâ, 12.7; NdIâ, 9.7; CaCl\\/sub ; 2\\/, 6.78; CaBrâ, 6.95; C aIâ, 10.0; SrClâ, 3.88;

A. S. Dworkin; M. A. Bredig

1963-01-01

341

(Fundamental studies of strongly magnetic rare earth-transition metal alloys)  

Microsoft Academic Search

The aim of this research is to deepen our understanding of new strongly magnetic rare earth-transition metal compounds and alloys. Such materials have high potential as hard or semi-hard permanent magnet materials with energy-related and other applications. The phases investigated generally are based on iron or cobalt, often include light rare earths, and often are ternary alloys with anisotropic hexagonal

1990-01-01

342

Diastereoselective pinacol coupling of alkyl aryl ketones with rare earth metals in the presence of chlorosilanes  

Microsoft Academic Search

Rare earth metals (Ln) are found to act as useful reducing agents for the pinacol coupling reaction of alkyl aryl ketones in the presence of chlorosilanes. Although the hitherto known pinacol coupling reaction using rare earth reducing agents generally exhibits very low diastereoselectivities, the present pinacol coupling by use of a LnR3SiCl system usually indicates higher diastereoselectivities. In particular, a

Akiya Ogawa; Hiroki Takeuchi; Toshikazu Hirao

1999-01-01

343

Low Temperature Resistivity of Yttrium-Based Alloys Containing Small Amounts of Rare Earth Metals  

Microsoft Academic Search

The resistivity of the dilute alloys of rare earth metals with yttrium has been measured at low temperatures. The result is in qualitative agreement with the recent theories due to Kondo and others on the s--d or s--f scattering. The effective s--f exchange integrals for various rare-earth solutes have been derived from the analysis of the resistivity data and compared

Tadashi Sugawara

1965-01-01

344

Metal-assisted SIMS and cluster ion bombardment for ion yield enhancement  

NASA Astrophysics Data System (ADS)

In addition to structural information, a detailed knowledge of the local chemical environment proves to be of ever greater importance, for example for the development of new types of materials as well as for specific modifications of surfaces and interfaces in multiple fields of materials science or various biomedical and chemical applications. But the ongoing miniaturization and therefore reduction of the amount of material available for analysis constitute a challenge to the detection limits of analytical methods. In the case of time-of-flight secondary ion mass spectrometry (TOF-SIMS), several methods of secondary ion yield enhancement have been proposed. This paper focuses on the investigation of the effects of two of these methods, metal-assisted SIMS and polyatomic primary ion bombardment. For this purpose, thicker layers of polystyrene (PS), both pristine and metallized with different amounts of gold, were analyzed using monoatomic (Ar +, Ga +, Xe +, Bi +) and polyatomic (SF 5+, Bi 3+, C 60+) primary ions. It was found that polyatomic ions generally induce a significant increase of the secondary ion yield. On the other hand, with gold deposition, a yield enhancement can only be detected for monoatomic ion bombardment.

Heile, A.; Lipinsky, D.; Wehbe, N.; Delcorte, A.; Bertrand, P.; Felten, A.; Houssiau, L.; Pireaux, J.-J.; De Mondt, R.; Van Vaeck, L.; Arlinghaus, H. F.

2008-12-01

345

Metal ion implantation and dynamic ion mixing for the protection of high-performance polymers from severe oxidative environment  

NASA Astrophysics Data System (ADS)

Low energy high-dose Plasma Immersion Ion Implantation, combining both ion and recoil implantation (dynamic ion mixing), was used to enrich thin surface layers of high-performance polymers with an appropriate amount of specially selected reactive metal element such as Al. Both oxygen plasma and fast ( E˜2-3 eV) atomic oxygen (FAO) beam have been used as aggressive environments for testing the implanted polymers. The modified materials successfully survived these test environments, including FAO, which is the main danger for carbon-based materials in space, in low Earth orbit. The retained doses of implanted and recoil implanted elements were controlled by RBS. The content, structure and morphology of the modified protective surface layers were examined by XPS and scanning electron microscopy (SEM). It was shown that protective oxide(s)-based surface structures were formed. Implantation and conversion conditions were found for which the appearance and important thermo-optical properties of treated polymer films, such as solar absorptance and thermal emittance, were practically unchanged.

Iskanderova, Z. A.; Kleiman, J. I.; Gudimenko, Y.; Tkachenko, A.; Tennyson, R. C.; Brown, I. G.; Monteiro, O. R.

1999-01-01

346

Syntheses, Characterization and Antitumour Activities of Rare Earth Metal Complexes with 2-(((4,6-dimethyl)-2-Pyrimidinyl)thio)Acetic Acid  

Microsoft Academic Search

Eight rare earth metal (III) complexes with 2-(((4,6-dimethyl)-2-pyrimidinyl)thio)-acetic acid, LnL3-nH2O [HL = 2-(((4,6-dimethyl)-2-pyrimidinyl)thio)-acetic acid; Ln = La, Ce, Pr, Nd, Sm Eu, Gd, Tb; n = 4 or 5], were prepared and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR and 1H-NMR. The results reveal that carboxyl group of the ligand coordinates with rare earth ions in bidentate

Jianqiang Qu; Liufang Wang; Yingqi Liu; Yumin Song; Yinyue Wang; Xiaofei Jia

2006-01-01

347

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

EPA Science Inventory

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

348

Matrix Elements and Operator Equivalents Connected with the Magnetic Properties of Rare Earth Ions  

Microsoft Academic Search

An account is given of the methods used to determine the matrix elements of crystal field potentials with particular reference to rare earth ions. Emphasis is laid on the importance of Wigner coefficients in such problems and the idea of using equivalent angular momentum operators is developed. For convenience in applying the results tables of matrix elements are included.

K W H Stevens; K. W. H

1952-01-01

349

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

350

Ion conics and counterstreaming electrons generated by lower-hybrid waves in the Earth's magnetosphere  

SciTech Connect

The exotic phenomenon of energetic ion-conic and counterstreaming electron formation by lower hybrid waves along the discrete field lines in the Earth's magnetosphere is considered. Mean particle calculations, plasma simulations, and analytical treatments of the acceleration processes are described.

Chang, T.; Crew, G.B.; Retterer, J.M.; Jasperse, J.R.

1989-04-01

351

Ion conics and counterstreaming electrons generated by lower hybrid waves in the Earth's magnetosphere  

SciTech Connect

The exotic phenomenon of energetic ion-conic and counterstreaming electron formation by lower hybrid waves along the discrete auroral field lines in the Earth's magnetosphere is considered. Mean particle calculations, plasma simulations, and analytical treatments of the acceleration processes are described.

Chang, T.; Crew, G.B.; Retterer, J.M.; Jasperse, J.R.

1989-04-01

352

Microwave phonon attenuation in rare-earth garnets: Ion-phonon interactions  

Microsoft Academic Search

Significant deviations from the behavior usual for dielectrics are observed in the ultrasonic attenuation at gigahertz frequencies in Nd, Gd, and Tb garnets and are attributed to the rare-earth ions. Relaxation of low-lying electron states by Orbach processes satisfactorily explains attenuation peaks in neodymium gallium garnet and terbium scandium aluminum garnet near 60 K. Below 20 K the attenuation in

M. Dutoit; J. C. Walling; D. S. Boudreaux

1975-01-01

353

Magnetic Exchange Interaction between Rare-Earth and Mn Ions in Multiferroic Hexagonal Manganites  

E-print Network

Magnetic Exchange Interaction between Rare-Earth and Mn Ions in Multiferroic Hexagonal Manganites D 2008; published 9 December 2008) We report a study of magnetic dynamics in multiferroic hexagonal in solids. Recently, superexchange was found to me- diate magnetoelectric (ME) coupling in multiferroics

354

Interactions of metal ions with ? synuclein and amyloid ? peptides  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

355

Ion Distributions Up- and Downstream of the Earth's Collisionless Bowshock Obtained Using Vlasiator  

NASA Astrophysics Data System (ADS)

We present ion distribution functions in the Earth's collisionless foreshock, bowshock and magnetosheath from 2D-3V simulations with Vlasiator, the world's first global magnetospheric hybrid-Vlasov simulation code. The unprecedented uniform discretization of the ion distribution functions in the velocity space at resolutions comparable to in-situ measurements allows detailed studies of backstreaming populations and wave-particle interactions in the foreshock, acceleration mechanisms at the bowshock and mirror-unstable distributions in the magnetosheath. We show that Vlasiator reproduces well-known observational features of ion distributions in the foreshock and the magnetosheath.

Kempf, Y.; Pokhotelov, D.; Vainio, R. O.; von Alfthan, S.; Koskinen, H. E.; Palmroth, M.

2013-12-01

356

Complementary Metal Ion Specificity of the Metal-Citrate Transporters CitM and CitH of Bacillus subtilis  

Microsoft Academic Search

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

Wil N. Konings; Jessica B. Warner; Bastiaan P. Krom; Juke S. Lolkema

2000-01-01

357

Extracellular Ribonuclease Production by Rhizopus stolonifer : Influence of Metal Ions  

Microsoft Academic Search

.   A strain of Rhizopus stolonifer produced high levels of extracellular ribonuclease (RNase) when grown on YPG (yeast extract, peptone, glucose) medium. Influence\\u000a of various medium components on the production of extracellular RNase activity showed that divalent metal ions had a marked\\u000a effect on growth and enzyme production. Maximum enzyme activity (3000 U\\/ml) was obtained in 5 days when the

Rohini Chacko; Mukund Deshpande; Vepatu Shankar

1996-01-01

358

Equilibrium sorption isotherm for metal ions on tree fern  

Microsoft Academic Search

A new sorbent system for removing heavy metal ions, such as Zn(II), Cu(II) and Pb(II), from aqueous solutions has been investigated. This new sorbent is tree fern, an agriculture product. Variables of the system include solution temperature and sorbent particle size. The experimental results were fitted to the Langmuir, Freundlich and Redlich–Peterson isotherms to obtain the characteristic parameters of each

Y. S. Ho; C. T. Huang; H. W. Huang

2002-01-01

359

Metal ion accumulation by immobilised cells of Brevibacterium sp  

Microsoft Academic Search

  This paper explores the use of an experimental system based on polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ for the removal of metal ions from solutions. Experiments were performed in columns filled with the immobilised\\u000a cells and challenged with influents containing 20?mg L?1 of lead and 10?mg L?1 of cadmium. The cells were able to accumulate lead (about 40?mg g?1

D Di Simine; C Finoli; A Vecchio; V Andreoni

1998-01-01

360

Interaction of heavy metal ions with ammonium humates  

SciTech Connect

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

Budaeva, A.D.; Zoltoev, E.V.; Tikhova, V.D.; Bodoev, N.V. [Russian Academy for Science, Buryatiya (Russian Federation)

2006-06-15

361

Precious metal catalysts with oxygen-ion conducting support  

Microsoft Academic Search

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

P. S. Ganguli; S. Sundaresan

1993-01-01

362

Metal loading effect on rare earth element binding to humic acid: Experimental and modelling evidence  

NASA Astrophysics Data System (ADS)

The effect of metal loading on the binding of rare earth elements (REE) to humic acid (HA) was studied by combining ultrafiltration and Inductively Coupled Plasma Mass Spectrometry techniques. REE-HA complexation experiments were performed at pH 3 for REE/C molar ratios ranging from ca 4 × 10 -4 to 2.7 × 10 -2. Results show that the relative amount of REE bound to HA strongly increases with decreasing REE/C. A middle-REE (MREE) downward concavity is shown by patterns at high metal loading, whereas patterns at low metal loading display a regular increase from La to Lu. Humic Ion Model VI modelling are close to the experimental data variations, provided that (i) the ?LK 2 parameter (i.e. the Model VI parameter taken into account the presence of strong but low density binding sites) is allowed to increase regularly from La to Lu (from 1.1 to 2.1) and (ii) the published log KMA values (i.e. the REE-HA binding constants specific to Model VI) are slightly modified, in particular with respect to heavy REE. Modelling approach provided evidence that logKdREE patterns with varying REE/C likely arises because REE binding to HA occurs through two types of binding sites in different density: (i) a few strong sites that preferentially complex the heavy REE and thus control the logKdREE atterns at low REE/C; (ii) a larger amount of weaker binding sites that preferentially complex the middle-REE and thus control the logKdREE pattern at high REE/C. Hence, metal loading exerts a major effect on HA-mediated REE binding, which could explain the diversity of published conditional constants for REE binding with HA. A literature survey suggests that the few strong sites activated at low REE/C could be multidentate carboxylic sites, or perhaps N-, or P-functional groups. Finally, an examination of the literature field data proposed that the described loading effect could account for much of the variation in REE patterns observed in natural organic-rich waters (DOC > 5 mg L -1 and 4 ? pH ? 7).

Marsac, Rémi; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

2010-03-01

363

Long-lived artificial ion clouds in the earth's ionosphere  

SciTech Connect

The authors report on two observations made over the Caribbean during the summer of 1991 of barium ion cloud releases, ten hours after the clouds were released. One release was made in the morning twilight, and one in the evening twilight, and each was observed again in the following twilight period by a low light level TV imager and a TV spectrograph onboard a Russian research vessel. These observations were very surprising at the time, but the authors present arguments as to why in retrospect they may not be so unusual in practise. Such cloud releases may provide very sensitive tests of ionspheric convection models.

Milinevsky, G.P. (Kiev Univ., Ukraine (Russian Federation)); Kashirin, A.I. (NPO Typhoon, Obninsk (Russian Federation)); Romanovsky, Yu.A. (Institute of Applied Geophysics, Moscow (Russian Federation)); Stenbaek-Nielson, H.C. (Univ. of Alaska, Fairbanks (United States)); Kelley, M.C. (Cornell Univ., Ithaca, NY (United States))

1993-06-07

364

Measurement of binding constants of poly(ethylenimine) with metal ions and metal chelates in aqueous media by ultrafiltration  

SciTech Connect

Equilibrium constants for the binding of poly(ethylenimine) (PEI) with metal ions and metal chelates of ethylenediaminetetraacetic acid and nitrilotriacetic acid in the aqueous sulfate solutions were determined by batch ultrafiltration (UF) in the pH range of 3.0--3.8. The average coordination number of PEI groups interacting with one metal ion and metal chelate was also obtained by varying the initial concentration ratio of PEI to metal ion. A simple chemical equilibrium model proposed in this work enabled the authors to satisfactorily predict the rejection coefficient of UF of metal ions and metal chelates in the presence of PEI. Also, the effect of the formation of soluble hydroxy complexes of metal chelates on their retention was emphasized.

Juang, R.S.; Chen, M.N. [Yuan-Ze Inst. of Technology, Taoyuan (Taiwan, Province of China). Dept. of Chemical Engineering] [Yuan-Ze Inst. of Technology, Taoyuan (Taiwan, Province of China). Dept. of Chemical Engineering

1996-06-01

365

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

SciTech Connect

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.

Lima, L. H. de [Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas, 13083-859, Campinas, SP (Brazil)] [Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas, 13083-859, Campinas, SP (Brazil); Cun, H. Y.; Hemmi, A.; Kälin, T.; Greber, T. [Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)] [Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)

2013-12-15

366

Ab initio calculations on the positive ions of the alkaline-earth oxides, fluorides, and hydroxides  

NASA Technical Reports Server (NTRS)

Theoretical dissociation energies are presented for the alkaline-earth fluoride, hydroxide, and oxide positive ions that are considered to be accurate to 0.1-0.2 eV. The r(e) for the positive ions are found to be consistently shorter than the corresponding neutrals by 0.07 + or -0.02 A. The bonding in the ground states is demonstrated to be of predominantly M + 2 X - character. The a 3 Pi and A 1 Pi are found to lie considerably above the X 1 Sigma + ground states of the alkaline-earth fluoride and hydroxide positive ions. The overall agreement of the theoretical ionization potentials with the available experimental appearance potentials is satisfactory; these values should represent the most accurate and consistent set available.

Partridge, H.; Langhoff, S. R.; Bauschlicher, C. W., Jr.

1986-01-01

367

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

368

DOI: 10.1002/chem.201002135 High Gas Sorption and Metal-Ion Exchange of Microporous MetalOrganic  

E-print Network

DOI: 10.1002/chem.201002135 High Gas Sorption and Metal-Ion Exchange of Microporous Metal of their potential ap- plications in gas storage, gas separation, catalysis, and fabri- cation of nanoparticles.[1 by the creation of open metal sites, through syn- thesis of catenated frameworks, and by imbedding metal

Paik Suh, Myunghyun

369

Adsorption of heavy metal ion from aqueous single metal solution by chemically modified sugarcane bagasse  

Microsoft Academic Search

This work describes the preparation of new chelating materials derived from sugarcane bagasse for adsorption of heavy metal ions in aqueous solution. The first part of this report deals with the chemical modification of sugarcane bagasse with succinic anhydride. The carboxylic acid functions introduced into the material were used to anchor polyamines, which resulted in two yet unpublished modified sugarcane

Osvaldo Karnitz; Leandro Vinicius Alves Gurgel; Júlio César Perin de Melo; Vagner Roberto Botaro; Tânia Márcia Sacramento Melo; Rossimiriam Pereira de Freitas Gil; Laurent Frédéric Gil

2007-01-01

370

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

PubMed

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

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

371

Enhancement of hypersensitive transitions of rare-earth ions in the near field of nanoobjects  

NASA Astrophysics Data System (ADS)

The change of intensities of optical transitions of atoms, molecules, and their ions in the near field of nanoobjects is of interest for researchers from both basic and applied points of view. The concept of a near field was used as early as the 1960s to study the mechanisms of hypersensitive transitions of rare-earth (RE) ions. In this work, it is once more emphasized that, precisely for these transitions, changes in characteristics under the action of local properties of the medium are especially strong and, correspondingly, these transitions are especially promising for use. The Judd method for the calculation of the intensities of hypersensitive transitions of RE ions taking into account the inhomogeneous ligand field is extended to RE ions in the near field of nanoobjects. A simple analytical expression for the Judd-Ofelt intensity parameter ?2 for RE ions in the field of spherical nanoparticles of a subwavelength size is derived.

Pukhov, K. K.; Sekatskii, S. K.

2014-05-01

372

Metal-silicate silicon isotope fractionation in enstatite meteorites and constraints on Earth's core formation  

NASA Astrophysics Data System (ADS)

Silicon has long been considered a possible light element in Earth 's core. If differences in 30Si/ 28Si ratios between metal (core) and silicate (mantle and crust) can be quantified, silicon isotopes may be used to constrain the amount of this element in the core, and in so doing elucidate the conditions that attended Earth 's differentiation. We investigate Si-isotope fractionation between metal and silicate in metal-rich enstatite meteorites as an analogue for Earth 's differentiation. We report here a 5 to 6‰ difference in the 30Si/ 28Si ratio between Si in metal and Si in silicate in the aubrites (enstatite achondrites) Mount Egerton and Norton County. The meteorites are believed to have derived from enstatite chondrites by melting and thermal metamorphism with final equilibration at 1200 and 1130 ± 80 K, respectively. Using the measured silicate-metal Si-isotope fractionation in these rocks we obtain a temperature dependence for fractionation of ?Si={7.64×10±0.471?T, in agreement with independent experimental and theoretical determinations. The measured silicate-metal fractionation suggests a ˜ 0.8‰ difference in the 30Si/ 28Si ratio between Earth 's core and mantle at P/ T conditions relevant to core formation. Our results, based on thermodynamic calculations for Si solubility in iron-rich metal and the measured Si-isotopic silicate-metal fractionation, imply at least ˜ 6 wt.% Si in the core (depending on the exact ?30Si BSE-chondrite value). The Si-isotope data also require that oxygen fugacity in the lower mantle increased during or after the process of core segregation by 1 to 2 log units.

Ziegler, Karen; Young, Edward D.; Schauble, Edwin A.; Wasson, John T.

2010-07-01

373

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

SciTech Connect

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.

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

2011-05-01

374

UPTAKE OF METAL IONS BY A NEW CHELATING ION-EXCHANGE RESIN. PART 2: ACID DEPENDENCIES OF TRANSITION AND POST-TRANSITION METAL IONS  

Microsoft Academic Search

Diphonixis a new dual-mechanism polyfunctional resin containing sulfonic and gem-diphosphonic acid groups. In Part 1 of this series the effectiveness of Diphonix in removing actinide ions from very acidic solutions was demonstrated. In this paper we report on the uptake of various transition and post-transition metal ions with Diphonix and two other resins for comparison. The results show that Diphonix

R. Chiarizia; E. P. Horwitz; R. C. Gatrone; S. D. Alexandratos; A. Q. Trochimczuk; D. W. Crick

1993-01-01

375

A new N-hydroxyethyliminodiacetic acid modified core-shell silica phase for chelation ion chromatography of alkaline earth, transition and rare earth elements.  

PubMed

Bare core-shell silica (1.7?m) has been modified with iminodiacetic acid functional groups via standard silane chemistry, forming a new N-hydroxyethyliminodiacetic acid (HEIDA) functionalised core-shell stationary phase. The column was applied in high-performance chelation ion chromatography and evaluated for the retention of alkaline earth, transition and heavy metal cations. The influence of nitric acid eluent concentration, addition of complexing agent dipicolinic acid, eluent pH and column temperature on the column performance was investigated. The efficiencies obtained for transition and heavy metal cations (and resultant separations) were comparable or better than those previously obtained for alternative fully porous silica based chelation stationary phases, and a similarly modified monolithic silica column, ranging from ?15 to 56?m HETP. Increasing the ionic strength of the eluent with the addition of KNO3 (0.75M) and increasing the column temperature (70°C) facilitated the isocratic separation of a mixture of 14 lanthanides and yttrium in under 12min, with HETP averaging 18?m (7?m for Ce(III)). PMID:24238706

McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Stack, Elaine M; Omamogho, Jesse O; Glennon, Jeremy D; Paull, Brett

2013-12-20

376

Studies on Microbial Heavy Metal Retention from Uranium Mine Drainage Water with Special Emphasis on Rare Earth Elements  

Microsoft Academic Search

Microbial heavy metal retention was studied using seepage water sampled from a former uranium mining site in Eastern Thuringia, Germany. The seepage water has a low pH and contains high concentrations of metals, including uranium, rare earth elements (REE), and other heavy metals. Microbial influence on sorption and\\/or active uptake of heavy metals was studied using REE patterns. Incubation of

D. Merten; E. Kothe; G. Büchel

2004-01-01

377

Quadrupole resonances in the rare-earth metals  

SciTech Connect

Calculations that employ a relativistic time-dependent local-density approximation to atomic absorption are used to examine a recent claim to the observation of giant quadrupolar resonances in the electron-energy-loss spectrum of Ce metal near the 4p edge. We confirm the existence of 4p..-->..4f resonances in this energy range but find the polarization effects much smaller than in typical giant dipole resonances.

Liberman, D.; Zangwill, A.

1989-01-01

378

Rare earth metal oxazoline complexes in asymmetric catalysis.  

PubMed

Polydentate oxazolines have been employed as highly effective stereodirecting ligands for asymmetric catalysis with metals from across most of the periodic table. Despite their highly versatile coordination chemistry, the use of these ligands tends to be polarised towards late transition metals; their use with early transition metals and the f-elements is significantly less developed. This current article aims to review the coordination chemistry and catalytic applications of Group 3 and lanthanide complexes supported by ligands possessing oxazoline moieties. Oxazoline-containing ligands were first employed in molecular lanthanide catalysis as early as 1997, yet there is still a significant void in the chemical literature in this respect. The ligands generally employed include bis(oxazolinyl)methane ("BOX"), 2,6-bis(oxazolinyl)pyridine ("pybox"), 1,1,1-tris(oxazolinyl)ethane ("trisox"), and others. The complexes are employed in a wide-range of catalytic applications, especially in Lewis acid catalysis, but also in the stereospecific polymerisation of olefins. PMID:22982883

Ward, Benjamin D; Gade, Lutz H

2012-11-01

379

Radiation damage from single heavy ion impacts on metal surfaces  

SciTech Connect

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

Donnelly, S.E. [Univ. of Salford, Manchester (United Kingdom); Birtcher, R.C. [Argonne National Lab., IL (United States). Materials Science Div.

1998-06-01

380

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

PubMed Central

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

S?balle, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken

2014-01-01

381

Adsorption of alkali, alkaline-earth, and 3d transition metal atoms on silicene  

NASA Astrophysics Data System (ADS)

The adsorption characteristics of alkali, alkaline-earth, and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, work function, and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na, and K, adsorb to hollow sites without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene, metalization of silicene takes place. Trends directly related to atomic size, adsorption height, work function, and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline-earth metals on silicene is entirely different from their adsorption on graphene. The adsorption of Be, Mg, and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo, and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic, and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal, and semiconducting behavior. For all metal adsorbates, the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

Sahin, H.; Peeters, F. M.

2013-02-01

382

Fluoride technology for obtaining high-energy magnetic alloys and ligatures based on rare-earth metals  

SciTech Connect

Unique specific properties of rare-earth metals (REMs) are to a large extent responsible for the technical progress in many branches of industry, science, and technology. A new fluoride procedure for obtaining high-energy magnetic alloys and ligatures based on rare-earth and transition metals has been proposed.

Buinovskii, A.S.; Sofronov, V.L.; Chizhikov, V.S.; Shtefan, Yu.P. [and others

1995-10-20

383

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

E-print Network

Dynamic polarizabilities of rare-earth-metal atoms and dispersion coefficients for their interaction with helium atoms Xi Chu Department of Chemistry, University of Montana, Missoula, Montana 59812; published 29 March 2007 The dynamic scalar and tensor polarizabilities of the rare-earth-metal atoms

Chu, Xi

384

Intrinsic and extrinsic properties of rare earth-transition metal compounds and permanent magnets  

Microsoft Academic Search

The revolutionary progress made in the field of permanent magnets over the past 25 years has been almost entirely due to a concentrated research effort in the field of rare earth-transition metal compounds. This paper discusses the unique intrinsic properties of such compounds as precursors for permanent magnets, and outlines possible coercivity mechanisms and their relationship with microstructure in the

J. P. Gavigan; D. Givord

1990-01-01

385

The hard-magnetic properties of rare earth-transition metal alloys  

Microsoft Academic Search

The intermetallic phases formed between the rare earth metals (R) and the elements of the 3-d transition series are a large group of new substances with interesting magnetic properties. They have been studied intensely in the last decade. Their properties are reviewed with a view toward their usefulness for permanent magnets. Some aspects of the recently developed magnets based on

KARL J. STRNAT

1972-01-01

386

Oxygen vacancies in transition metal and rare earth oxides: Current state of understanding and remaining challenges  

Microsoft Academic Search

Defects at transition metal (TM) and rare earth (RE) oxide surfaces, neutral oxygen vacancies in particular, play a major role in a variety of technological applications. This is the motivation of numerous studies of partially reduced oxide surfaces. We review, discuss, and compare theoretical data for structural and electronic properties and energetic quantities related to the formation of oxygen defects

M. Verónica Ganduglia-Pirovano; Alexander Hofmann; Joachim Sauer

2007-01-01

387

Study of double layer rare earth metal conversion coating on aluminum alloy LY12  

Microsoft Academic Search

The process of the double layer rare earth metal (REM) conversion coating on aluminum alloy LY12 (2024) was introduced in this paper. The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy. The results showed that the coating increased the corrosion resistance (Rp) of the alloy surface, thus reducing the driving force of corrosion. The morphologies of

Yu Xingwen; Cao Chunan; Yao Zhiming; Zhou Derui; Yin Zhongda

2001-01-01

388

Influence of rare-earth metals on electrophysical properties of glassy films, deposited from solutions  

SciTech Connect

The possibility of altering the properties of solution-deposited, boron-doped, glassy films is demonstrated by the addition of rare-earth metals. The use of sublimated r.e.m.'s during the formation of the doped films improves the properties of the films considerably on the account of the decrease in the nonferrous-impurity contents in them.

Sechenov, D.A.; Savitskii, E.M.; Chupryakov, Yu.A.; Chistyakov, O.D.

1986-12-01

389

SOME EFFECTS OF ANISOTROPY ON SPIRAL SPIN-CONFIGURATIONS WITH APPLICATION TO RARE-EARTH METALS  

Microsoft Academic Search

A theoretical study of effects of anisotropy on spiral spin-; configurations is presented, emphasizing the problem of the magnetic ordering in ; rare-earth metals. It is shown that the ferromagnetic spiral observed at low ; temperatures by Wilkinson, Koehler, Wollan, and Cable in erbium can be the ; classical ground state of a spin Hamiltonian containing exchange and anisotropy ;

T. Kaplan

1961-01-01

390

Corrosion behavior of rare earth metal (REM) conversion coatings on aluminum alloy LY12  

Microsoft Academic Search

The processes of the double layer rare earth metal (REM) conversion coating on aluminum alloy LY12 (2024) were introduced. The results of polarization tests showed that the corrosion resistance of the double layer REM conversion coating was superior to that of chromate conversion coating. The corrosion behavior of REM conversion coatings on LY12 alloy was studied with optical microscopy and

Yu Xingwen; Cao Chunan; Yao Zhiming; Zhou Derui; Yin Zhongda

2000-01-01

391

Energy position of 4f levels in rare-earth metals  

Microsoft Academic Search

The energy position of the occupied and unoccupied 4f levels relative to the Fermi energy is studied for the rare-earth metals. This is done by treating the excited state as an impurity in an otherwise perfect crystal. This picture is first considered in the complete screening approximation. In this approximation thermochemical data can be used directly to give energy values

Börje Johansson

1979-01-01

392

Rare earth metal oxides: formation, characterization and catalytic activity Thermoanalytical and applied pyrolysis review  

Microsoft Academic Search

This review provides a guide to the recent literature on the characterization of the decomposition routes of different precursors, especially carboxylates of rare earth metals (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Th), and the formation of the final oxide products. It also discusses the effects of 1.(1) the nature of

Gamal A. M. Hussein

1996-01-01

393

Depolarization theory of. mu. /sup +/-mesons in rare earth metals near the NEEL point  

SciTech Connect

The depolarization of ..mu../sup +/-mesons in heavy rare earth metals near the NEEL point is studied. A relationship between the depolarization rate and the temporal correlation functions is found for the varying magnetic field of the medium in the meson localization point. Equations for the polarization characteristics per unit of time in single crystals and in polycrystals are established.

Ivanter, I.G.; Fomichev, S.V.

1980-06-01

394

Point-defect properties in HCP rare earth metals with analytic modified embedded atom potentials  

Microsoft Academic Search

The analytic embedded atom method (EAM) type many-body potentials of hcp rare earth metals (Dy, Er, Gd, Ho, Nd, Pr, and Tb) have been constructed. The hcp lattice is shown to be energetically most stable when compared with the fcc and bcc structure, and the hcp lattice with ideal c\\/a. The mechanical stability of the corresponding hcp lattice with respect

Wangyu Hu; Huiqiu Deng; Xiaojian Yuan; Masahiro Fukumoto

2003-01-01

395

Shaping of diamond films by etching with molten rare-earth metals  

Microsoft Academic Search

A method is presented for shaping and thinning of CVD diamond films which does not involve high pressures of hydrogen atmospheres; it instead makes use of such molten rare-earth metals as Ce or La to etch away the surface of the diamond film. The process yields appreciable results over periods of a few hours, and may render diamond film applications

S. Jin; J. E. Graebner; M. McCormack; T. H. Tiefel; A. Katz; W. C. Dautremont-Smith

1993-01-01

396

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

Microsoft Academic Search

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⁻¹ aqueous solution of

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

1995-01-01

397

Investigation of the structure of glassy phosphates of rare-earth metals  

SciTech Connect

The authors use x-ray and IR spectrometry to study the structure of glassy lanthanum, neodymium, gadolinium, and erbium polyphosphates and neodymium, gadolinium, erbium and lutecium ultraphosphates. It was found that the structures of all ultraphosphate glasses are similar and that there are two types of structures depending on the atomic number of the rare-earth metal in the glassy polyphosphates.

Strugach, L.S.; Kuz'menkov, M.I.; Sergeeva, N.M.; Soklakov, A.I.

1986-04-01

398

Composition of Earth's core from gallium metal-silicate partitioning experiments  

NASA Astrophysics Data System (ADS)

Earth's Core formation has left an imprint in the composition of the mantle, by depleting and fractionating the siderophile trace elements. However, some siderophile element concentrations in Earth's mantle cannot be explained by simple metal-silicate partitioning during the accretion and core formation. Gallium, for instance, is a moderately siderophile element which is not depleted in Earth's mantle relative to the lithophile volatility trend, and therefore shows the characteristics of a lithophile element. This peculiarity cannot be explained by any accretion/core formation scenario in the literature. This is due to the fact that all studies of the partitioning of gallium between metal and silicate (with the effects of pressure, temperature, silicate composition and redox) have shown it to remain siderophile. We will present our study of the effect of metal composition on the partitioning of gallium. Light elements (silicon and sulphur in our study) in the core should affect the activity coefficient of gallium in the metal, and hence its partitioning between metal and silicate. We performed a series of isobaric and isothermal experiments (2 GPa, 1800°C) in an end-loaded piston cylinder press, and varied the Si and S content of the metal phase. We observed that the addition of Si and S makes gallium more lithophile, and this illustrates once more that the light elements present in the core play a fundamental role in metal-silicate equilibrium and in explaining the abundance of trace elements in Earth's mantle. We will also present models core formation that are compatible with our measurements.

Blanchard, I.; Badro, J.; Siebert, J.

2012-12-01

399

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

PubMed

The electron-transfer based quenching effect of commonly encountered transition metal ions on the photoluminescence of grapheme quantum dots (GQDs) was for the first time investigated, and was found to be associated with electron configuration of the individual metal ion. Ethylene diamine tetraacetic acid (EDTA), the metal ion chelator, can competitively interact with metal ions to recover the quenched photoluminescence of GQDs. Basically, metal ions with empty or completely filled d orbits could not quench the photoluminescence of GQDs, but this quenching effect was observed for the metal ions with partly filled d orbits. Based on the quenching-recovering strategy, a simple optical metal sensing platform was established by taking Ni(2+) as an example. Using the nickel ion-specific chelating reagent, dimethylglyoxime (DMG), to replace EDTA, a detection limit of 4.1 ?M was obtained in standard solution. This proposed strategy does not need further functionalization of GQDs, facilitating the application for simple, fast and cost-effective screening of metal ions. PMID:24209324

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

2013-12-15

400

Half metallic ferromagnetism in alkaline-earth metal nitrides XN (X=Ca, Sr and Ba): A first principles study  

NASA Astrophysics Data System (ADS)

The structural, electronic, mechanical and magnetic properties of 3 alkaline-earth metal nitrides (XN: X=Ca, Sr, and Ba) are investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation code. At ambient pressure all the 3 nitrides are stable in the ferromagnetic state with a cubic NaCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials are half metallic ferromagnets at normal pressure. A pressure-induced structural phase transition from NaCl (B1) to CsCl (B2) phase is observed in CaN, SrN and BaN. On further increasing the pressure, a half metallic to metallic transition is also observed in these nitrides. Ferromagnetism is quenched in all the 3 nitrides at high pressures.

Palanichamy, R. Rajeswara; Priyanga, G. Sudha; Cinthia, A. Jemmy; Murugan, A.; Meenaatci, A. T. Asvini; Iyakutti, K.

2013-11-01

401

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

PubMed

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

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

2014-06-10

402

Catalytic properties of ion-bombarded non-metals  

NASA Astrophysics Data System (ADS)

Sputtering, ion implantation and ion beam mixing are useful new techniques for producing catalysts consisting of an active metal introduced in a non-active substrate. We studied the performance of implanted and ion beam mixed electrocatalysts containing platinum as the active component in graphite or RuO 2 substrates. The specimens were used as electrodes in electrochemical cells and their activity was studied for the oxidation of formic acid and methanol, the reduction of oxygen and the evolution of hydrogen. All reactions are important for fuel cells and hydrogen production. The intermixing of a thin Pt layer with a RuO 2 substrate by means of 150 keV Kr + beams did not change the activity, normalized to a standard Pt surface concentration, for formic acid oxidation and oxygen reduction. The activity for methanol oxidation, however, decreased with increasing mixing dose and was nearly zero for implanted Pt in RuO 2. For Pt on graphite substrates the activity for all reactions increased with the mixing dose up to 10 16{Kr +}/{cm 2}, and decreased or saturated above this value. The observed dependency of the activity on the individual chemical reaction as well as on the type of substrate was explained provisionally by a cooperation of small particle effects and metal-substrate interactions.

Wolf, G. K.; Zucholl, K.; Folger, H.

1984-02-01

403

Rare earth zirconium oxide buffer layers on metal substrates  

DOEpatents

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.

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

404

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

Microsoft Academic Search

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

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

1999-01-01

405

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

406

Earth  

NASA Technical Reports Server (NTRS)

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.

Carr, M. H.

1984-01-01

407

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

408

Ternary rare earth and actinoid transition metal carbides viewed as carbometalates  

SciTech Connect

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.

Dashjav, Enkhtsetseg [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Kreiner, Guido [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Schnelle, Walter [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Wagner, Frank R. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Kniep, Ruediger [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany)], E-mail: Kniep@cpfs.mpg.de; Jeitschko, Wolfgang [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Wilhelm-Klemm-Strasse 8, D-48149 Muenster (Germany)], E-mail: jeitsch@uni-muenster.de

2007-02-15

409

Size-dependent patterned recognition and extraction of metal ions by a macrocyclic aromatic pyridone pentamer.  

PubMed

A macrocyclic aromatic pyridine pentamer was found to exhibit patterned recognition of metal ions and efficiently extract larger ions, such as Cs(+), Ba(2+), Tl(+), Au(+), K(+) and Rb(+) preferentially over the other 18 smaller metal ions from the aqueous phase into the chloroform layer. PMID:25200048

Shen, Jie; Ma, Wenliang; Yu, Lin; Li, Jin-Bo; Tao, Hu-Chun; Zhang, Kun; Zeng, Huaqiang

2014-10-28

410

The alkali and alkaline earth metal doped ZnO nanotubes: DFT studies  

NASA Astrophysics Data System (ADS)

Doping of several alkali and alkaline earth metals into sidewall of an armchair ZnO nanotube has been investigated by employing the density functional theory in terms of energetic, geometric, and electronic properties. It has been found that doping processes of the alkali and alkaline metals are endothermic and exothermic, respectively. Based on the results, contrary to the alkaline metal doping, the electronic properties of the tube are much more sensitive to alkali metal doping so that it is transformed from intrinsic semiconductor with HOMO-LUMO energy gap of 3.77 eV to an extrinsic semiconductor with the energy gap of ~1.11-1.95 eV. The doping of alkali and alkaline metals increases and decreases the work function of the tube, respectively, which may influence the electron emission from the tube surface.

Peyghan, Ali Ahmadi; Noei, Maziar

2014-01-01

411

Application of the mobile metal ion technique to routine geochemical exploration  

Microsoft Academic Search

Extractants containing strong ligands may be used to detach unbound or weakly attached metal ions from soils, resulting in `Mobile Metal Ions' (MMI) in concentrations readily measurable by modern-day inductively coupled plasma (ICP) analytical equipment. Mobile forms of metals Cu, Pb, Zn, Ni, Cd, Au, Ag, Co and Pd can be extracted with two digestants, and in general show strong

A. W Mann; R. D Birrell; A. T Mann; D. B Humphreys; J. L Perdrix

1998-01-01

412

The connection between metal ion affinity and ligand affinity in integrin I domains  

E-print Network

The connection between metal ion affinity and ligand affinity in integrin I domains Thomas Vorup in regulating ligand binding has been reported, the relationship between metal ion binding affinity and ligand binding affinity has not been elucidated. Metal and ligand binding by several I domain mutants

Springer, Timothy A.

413

Templated display of biomolecules and inorganic nanoparticles by metal ion-induced peptide nanofibers.  

PubMed

We functionalized peptide nanofibers to provide a nano-scale template for the display of biomolecules and inorganic nanoparticles using metal ion coordination. Nanofibers assembled only in the presence of certain divalent metal ions, and could be readily dissolved by a metal-chelating reagent, EDTA. PMID:20177599

Lee, Byoung-Chul; Zuckermann, Ronald N

2010-03-14

414

High-resolution mass spectrometer for liquid metal ion sources.  

PubMed

Recently, a mass spectrometer for liquid metal ion sources (LMIS) has been built and set into operation. This device uses an E × B-filter as mass dispersive element and provides sufficient resolution to analyse the emission of clusters from LMIS to much higher mass ranges (>2000 amu) than commercially available mass filters for focused ion beam systems. It has also been shown that for small masses the composition of clusters from different isotopes can be resolved. Furthermore, a rather high fluence of monodisperse clusters in the range of 10(6)-10(7) clusters/s can be achieved with this setup. This makes it a promising tool for the preparation of mass selected clusters. In this contribution, theoretical considerations as well as technical details and the results of first measurements are presented. PMID:24089821

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

2013-09-01

415

EPR investigations of mesoporous silica doped with metal transitions ions  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance (EPR) experiments were performed on mesoporous silica powders in which (1,4,8,11-tetraazacyclotetradecane) cyclam groups were incorporated. These functionalised groups allow an easy binding with copper and nickel ions. Comparative studies are carried out on samples functionalised by cyclam groups located either inside the pores or in the walls of the mesoporous structures. Copper and nickel EPR parameters, including g-tensors and hyperfine components are determined and relevant electronic, magnetic and structural information are obtained. The EPR spectra intensities and line-widths are investigated on the temperature range [4 K,300 K] to clarify the relative dispersion or agglomeration of the doping ions in the matrices as well as their possible thermally activated mobility and ions pairing. As a support of the experimental EPR investigations, numerical simulations of the geometry of metallic ion environments and their electronic properties are carried out and discussed. The possibility of dynamic Jahn Teller (JT) effect in the temperature range [200, 60 K] is discussed for the nickel doped matrices where the low temperature quenched JT configuration is thought to favour the formation of Ni3+ pairs.

Kassiba, A.; Makowska-Janusik, M.; Alauzun, J.; Kafrouni, W.; Mehdi, A.; Reyé, C.; Corriu, R. J.; Gibaud, A.

2006-04-01

416

Isotope fractionation in surface ionization ion source of alkaline-earth iodides  

SciTech Connect

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.

Suzuki, T.; Kanzaki, C.; Nomura, M.; Fujii, Y. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8550 (Japan)

2012-02-15

417

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

SciTech Connect

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.

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

1999-06-13

418

Spectropolarimetric titrimetry of metal ions and optically active chelating agents  

E-print Network

-Metal Ion Systems Titration of Al(010&)s with standard 1-PDTR 4. Titration of In(C104)s with standard 1-PDTA 5. Titration of Tl(010~)s with standard 1-PDTA 6. Titration oi' ZrO(C10a)a with star. dard 1-PDTR '7. Titrat on of Th(010'). with standard 1...-PDTA 8. Titration of . a(NOs)s with standard 1-PDTA 9. Titration of CeCls with standard 1-PDTA 10. Titration of Pr(0104)s with standard 1-PDTA 11. Titration of Nd(010&)s with standard 1-PDTA 12. Titration oi' Sm(0104)s with standard 1-PDTA 13...

Caldwell, Donald Lee

2012-06-07

419

Assessment of the Antiviral Properties of Zeolites Containing Metal Ions  

Microsoft Academic Search

The antiviral properties of zeolite (sodium aluminosilicate) powders amended with metal ions were assessed using human coronavirus\\u000a 229E, feline infectious peritonitis virus (FIPV), and feline calicivirus F-9. Zeolites containing silver and silver\\/copper\\u000a caused significant reductions of coronavirus 229E after 1 h in suspension. The silver\\/copper combination yielded a >5.13-log10 reduction within 24 h. It was also the most effective (>3.18-log10) against FIPV

Kelly R. Bright; Enue E. Sicairos-Ruelas; Patricia M. Gundy; Charles P. Gerba

2009-01-01

420

Proton di-ionizable p-tert-butylcalix[4]arene-crown-6 compounds in cone, partial-cone and 1,3-alternate conformations: synthesis and alkaline earth metal cation extraction.  

PubMed

Novel proton di-ionizable p-tert-butylcalix[4]arene-crown-6 compounds in cone, partial-cone and 1,3-alternate conformations are synthesized to compare the efficiency and selectivity with which they extract alkaline earth metal ions. In these ligands, a crown-6 polyether unit links alternate aromatic rings of the calix[4]arene framework. To the remaining lower-rim positions are attached oxyacetic acid or N-(X)sulfonyl oxyacetamide groups. Changing the conformation varies the spatial relationship between a polyether-complexed divalent metal ion and the ionized side arms of the ligands. This is found to markedly affect the efficiency and selectivity in competitive solvent extraction of alkaline earth metal ions from aqueous solutions into chloroform by the di-ionizable calix[4]arene-crown-6 ligands. PMID:15858649

Zhou, Hui; Surowiec, Kazimierz; Purkiss, David W; Bartsch, Richard A

2005-05-01

421

A THEORETICAL INVESTIGATION OF SOME MAGNETIC AND SPECTROSCOPIC PROPERTIES OF RARE-EARTH IONS  

Microsoft Academic Search

Investigations of some magnetic and spectroscopic properties of rare-; earths ions based on approximate HartreeFock calculations are reported. A set of ; convertional, nonrelativistic Hartree-Fock wave functions were obtained for Ce\\/; sup 3+\\/, Pr\\/sup 3+\\/, Nd\\/sup 3+\\/, Sm\\/sup 8+\\/, Eu\\/sup 2+\\/, Gd\\/sup 3+\\/, Dy\\/sup 3+\\/, ; Er\\/sup 3+\\/, and Yb\\/sup 3+\\/. After these calculations for Ce\\/sup 3+\\/ were carried ;

A. J. Freeman; R. E. Watson

1962-01-01

422

Photon echoes in an amplifying rare-earth-ion-doped crystal.  

PubMed

We report what we believe is the first experimental demonstration of photon echoes in an amplifying rare-earth-ion-doped crystal. Population inversion is achieved by optical pumping, which yields high-power photon echoes, with an energy gain of as much as a factor of 5. Effects of the pump on the photon echo process highlight the advantages of an amplifying crystal. New questions concerning the optical dephasing mechanisms in Er3+:YSO have arisen. PMID:15981509

Crozatier, V; Gorju, G; Bretenaker, F; Le Gouët, J L; Lorgeré, I; Baldit, E

2005-06-01

423

Ion engine propelled Earth-Mars cycler with nuclear thermal propelled transfer vehicle, volume 2  

NASA Technical Reports Server (NTRS)

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.

Meyer, Rudolf X.; Baker, Myles; Melko, Joseph

1994-01-01

424

NIR Persistent Luminescence of Lanthanide Ion-Doped Rare-Earth Oxycarbonates: The Effect of Dopants.  

PubMed

A series of luminescent rare-earth ion-doped hexagonal II-type Gd oxycarbonate phosphors Gd2-xRExO2CO3 (RE = Eu(3+), Yb(3+), Dy(3+)) have been successfully synthesized by thermal decomposition of the corresponding mixed oxalates. The Yb(3+) doped Gd-oxycarbonate has evidenced a high persistent luminescence in the NIR region, that is independent from the temperature and makes this materials particular attractive as optical probes for bioimaging. PMID:25285437

Caratto, Valentina; Locardi, Federico; Costa, Giorgio Andrea; Masini, Roberto; Fasoli, Mauro; Panzeri, Laura; Martini, Marco; Bottinelli, Emanuela; Gianotti, Enrica; Miletto, Ivana

2014-10-22

425

Enhanced superconductivity by rare-earth metal doping in phenanthrene.  

PubMed

We successfully synthesized La- and Sm-doped phenanthrene powder samples and observed superconductivity in them at T(c) around 6 K. The T(c)s are 6.1 K for La(1) phenanthrene and 6.0 K for Sm(1) phenanthrene, which are enhanced by about 1 and 0.5 K compared to those in A(3) phenanthrene (A = K and Rb) and in Ae(1.5) phenanthrene (Ae = Sr and Ba) superconductors, respectively. The superconductive shielding fractions for La(1) phenanthrene and Sm(1) phenanthrene are 46.1% and 49.8% at 2 K, respectively. The small effect of doping with the magnetic ion Sm(3+) on T(c) and the positive pressure dependence coefficient of T(c) strongly suggest unconventional superconductivity in the doped phenanthrene superconductors. The charge transfer to organic molecules from dopants of La and Sm induces a redshift of 7 cm(-1) per electron for the mode at 1441 cm(-1) in the Raman spectra, which is almost the same as those observed in A(3) phenanthrene (A = K and Rb) and Ae(1.5) phenanthrene (Ae = Sr and Ba) superconductors. PMID:22872048

Wang, X F; Luo, X G; Ying, J J; Xiang, Z J; Zhang, S L; Zhang, R R; Zhang, Y H; Yan, Y J; Wang, A F; Cheng, P; Ye, G J; Chen, X H

2012-08-29

426

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

SciTech Connect

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.

Shawki, Ali [Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, P.O. Box 670576, Cincinnati, OH 45267-0576 (United States)] [Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, P.O. Box 670576, Cincinnati, OH 45267-0576 (United States); Mackenzie, Bryan, E-mail: bryan.mackenzie@uc.edu [Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, P.O. Box 670576, Cincinnati, OH 45267-0576 (United States)] [Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, P.O. Box 670576, Cincinnati, OH 45267-0576 (United States)

2010-03-12

427

Optical detection of a single rare-earth ion in a crystal  

PubMed Central

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 Pr3+ 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 Pr3+ 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

Kolesov, R.; Xia, K.; Reuter, R.; Stohr, R.; Zappe, A.; Meijer, J.; Hemmer, P.R.; Wrachtrup, J.

2012-01-01

428

New Rare-Earth Transition-Metal Intermetallic Compounds and Metastable Phases for Permanent Magnetic Materials  

Microsoft Academic Search

After three generations of the discovery of rare-earth permanent magnets, based on SmCo5, Sm2Co17 and Nd2Fe14B Compounds, a great effort has been made on researching new rare-earth transition-metal (R-T) intermetallic Compounds in\\u000a permanent magnetic materials. The aim is to have a better understanding of structural and magnetic properties of the intermetallics\\u000a and to find new R-T Compounds possessing good intrinsic

Z. D. Zhang

429

First-Principles Calculation of Solution Energy of Alkaline-Earth Metal Elements to BaTiO3  

NASA Astrophysics Data System (ADS)

Quantitative analysis of the solution energy of alkaline-earth metal elements to perovskite-type BaTiO3 was carried out by a first-principles calculation combined with thermodynamics theory. The solution energies of neutral solute and a compensated solute with an oxygen vacancy were systematically calculated. They were obtained for two cation sites and four thermodynamical conditions with different chemical potentials of constituent atoms. Both Ca and Sr preferably occupy the Ba site of BaTiO3. On the other hand, Mg occupies the Ti site. This corresponds well to the widely accepted experimental findings regarding site preference. Moreover, under the condition of coexising BaO, CaO and BaTiO3, energy difference between the Ba-site solution and O-vacancy compensated Ti-site solution of Ca ions has been found to be smaller than that of Sr. Under this condition, the O-vacancy compensated Ti-site solution of Ca should be favorable compared with that of Sr. The same number of oxygen vacancies as Ca ions occupying Ti sites can be introduced. This also explains well experimental feature of the Ca-doped BaTiO3-based nonreducible multilayer ceramics capacitor (MLCC) materials regarding solution site of the Ca ion and abundance of O-vacancy.

Moriwake, Hiroki; Hirayama, Tsukasa; Ikuhara, Yuichi; Tanaka, Isao

2007-10-01

430

Photoluminescence properties of Jahn-Teller transition-metal ions  

NASA Astrophysics Data System (ADS)

This work investigates the influence of electron-phonon coupling associated with E ?e and T ?e Jahn-Teller (JT) effect in different transition-metal (TM) ions on de-excitation phenomena through nonradiative multiphonon relaxation, i.e., photoluminescence (PL) quenching. We developed a configurational curve model which is able to predict from the absorption spectrum whether a given JT-TM ion is PL or quenched. The prediction is made on the basis of an adapted Dexter-Klick-Russell parameter for JT systems, defined in terms of spectroscopic parameters through ?JT=??eabs/Eabs, where ?eabs refers to the splitting of the parent octahedral Eg states by the JT distortion in E ?e (? =3/4) or T ?e (? =1/4), and Eabs is the energy of the first absorption band involving electronic transition between Eg and T2g. We show that PL in any JT-TM ion occurs whenever ?JT<0.1 or is quenched if ?JT>0.2. This result is noteworthy since it allows us to establish structural requirements for the JT-TM ion and the host crystal to be PL. Although PL properties of materials containing TM ions depend on a variety of structural factors such as the electronic configuration, the site symmetry, and the crystal field produced by neighboring atoms, the present model achieves this goal through a simple spectroscopic parameter: ?JT. In this work we correlated the PL properties of different sixfold-coordinated JT systems such as Ti3+, Cu2+, Mn3+, Cr2+, Fe2+, Co3+, and Ni3+ in halides and oxides with ?JT obtained from their respective absorption spectra. From this analysis we conclude that depending on the nature of the JT coupling and its strength, PL is either strongly favored or quenched in T ?e while it is mostly quenched in E ?e systems due to the larger JT distortion.

Sanz-Ortiz, Marta N.; Rodríguez, Fernando

2009-09-01

431

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

SciTech Connect

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

Kato, M. (Waseda Univ., Tokyo, Japan); Nishide, H.; Tsuchida, E.; Sasaki, T.

1981-07-01

432

Cooperative thermodynamic control of selectivity in the self-assembly of rare earth metal-ligand helices.  

PubMed

Metal-selective self-assembly with rare-earth cations is possible with suitable rigid, symmetrical bis-tridentate ligands. Kinetically controlled formation is initially observed, with smaller cations preferentially incorporated. Over time, the more thermodynamically favorable complexes with larger metals are formed. This thermodynamic control is a cooperative supramolecular phenomenon and only occurs upon multiple-metal-based self-assembly: single-metal ML3 analogues do not show reversible selectivity. The selectivity is dependent on small variations in lanthanide ionic radius and occurs despite identical coordination-ligand coordination geometries and minor size differences in the rare-earth metals. PMID:24206215

Johnson, Amber M; Young, Michael C; Zhang, Xing; Julian, Ryan R; Hooley, Richard J

2013-11-27

433

Selective recovery of gold and other metal ions from an algal biomass  

Microsoft Academic Search

The authors observed that the pH dependence of the binding of Au\\/sup 3 +\\/, Ag\\/sup +\\/, and Hg\\/sup 2 +\\/ to the algae Chlorella vulgaris is different than the binding of other metal ions. Between pH 5 and 7, a variety of metal ions bind strongly to the cell surface. Most of these algal-bound metal ions can be selectively desorbed

Dennis W. Darnall; Benjamin Greene; Michael T. Henzl; J. Michael Hosea; Robert A. McPherson; Joseph Sneddon; M. Dale Alexander

1986-01-01

434

Measurement of hold-up times in a thermal ion source for metallic and monoxide ions of lanthanum and cerium  

Microsoft Academic Search

Hold-up times of ions in a thermal ion source were measured for lanthanum and cerium together with neighboring elements in the periodic table. The hold-up times of metallic and monoxide ions of both lanthanum and cerium were found to be almost the same and much longer than those of cesium, barium, praseodymium and neodymium ions. The observed long hold-up times

S. Ichikawa; T. Sekine; H. Iimura; M. Oshima

1992-01-01

435

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

SciTech Connect

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

Tsuji, M. (Department of Chemistry, Faculty of Science, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152 (Japan)); Komarneni, S. (Materials Research Laboratory and Department of Agronomy, The Pennsylvania State University, University Park, Pennsylvania 16802-4801 (United States))

1993-03-01

436

Uptake of alkaline earth metals in Alcyonarian spicules (Octocorallia)  

NASA Astrophysics Data System (ADS)

Alcyonarian corals (Octocorallia) living in shallow tropical seas produce spicules of high-Mg calcite with ˜13 mol% MgCO3. We cultured the tropical alcyonarian coral Rhythisma fulvum in experiments varying temperature (19-32 °C) and pH (8.15-8.44). Alkalinity depletion caused by spicule formation systematically varied in the temperature experiments increasing from 19 to 29 °C. Spicules were investigated for their elemental ratios (Mg/Ca, Sr/Ca) using ICP-OES, ?44/40Ca using TIMS, as well as ?18O and ?13C by IRMS. Mg/Ca increased with temperature from 146 to 164 mmol/mol, in good agreement with the range observed for marine inorganic calcite. Mg/Ca increased by 1.0 ± 0.4 mmol/mol/°C, similar to the sensitivity of Miliolid foraminifera. The pH experiments revealed a linear relationship between Mg/Ca and carbonate ion concentration of +0.03 ± 0.02 mmol/mol/?Mol. Sr/Ca ranges from 2.5 to 2.9 mmol/mol being in good agreement with other high-Mg calcites. Temperature and pH experiments showed linear dependencies of Sr/Ca matching inorganic calcite trends and pointing to a decoupling of crystal precipitation rate and calcification rate. Ca isotopes range between 0.7‰ and 0.9‰ in good agreement with aragonitic scleractinian corals and calcitic coccoliths. Presumably Ca isotopes are fractionated by a biological mechanism that may be independent of the skeletal mineralogy. We observe no temperature trend, but a significant decrease of ?44/40Ca with increasing pH. This inverse correlation may characterise biologically controlled intracellular calcification. Oxygen isotope ratios are higher than expected for isotopic equilibrium with a temperature sensitivity of -0.15 ± 0.03‰/°C. Carbon isotope ratios are significantly lower than expected for equilibrium and positively correlated with temperature with a slope of 0.20 ± 0.04‰/°C. Many of our observations on trace element incorporation in R. fulvum may be explained by inorganic processes during crystal formation, which do not comply with the intracellular mode of calcification in Alcyonarian corals. The observed elemental and isotopic compositions, however, could be explained if the partitioning caused by biological mechanisms mimics the effects of inorganic processes.

Taubner, I.; Böhm, F.; Eisenhauer, A.; Garbe-Schönberg, D.; Erez, J.

2012-05-01

437

JOURNAL DE PHYSIQUE Colloque C5, suppliment au no 5, Tome 40, Mai 1979,page C5-46 High-temperature Hall effect in rare earth metals  

E-print Network

-temperature Hall effect in rare earth metals M. V. Vedernikov, V. G. Dvunitkin and N. I. Moreva A. F. Ioffe. Abstract. - Up to date the Hall effect in rare earth metals (REM) was studied rather extensively below at http://dx.doi.org/10.1051/jphyscol:1979518 #12;HIGH-TEMPERATURE HALL EFFECT IN RARE EARTH METALS C5

Paris-Sud XI, Université de

438

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

NASA Astrophysics Data System (ADS)

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

Devi, Jai; Batra, Nisha; Malhotra, Rajesh

2012-11-01

439

A non-contaminating method for preparing intra-rare-earth alloys containing volatile and non-volatile metals  

Microsoft Academic Search

The preparation of alloys containing one to two percent of the volatile lanthanide metals Sm, Eu, Tm and Yb in the high melting point (HMP) rare earth metals Sc, Y and Lu was accomplished by a vapor deposition, diffusion method without crucible contamination. The method avoids the melting of the HMP metals which would introduce impurities from the crucible generally

B. J. Beaudry; F. C. Laabs

1991-01-01

440

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

E-print Network

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 ...

Meng, Shirley Y.

441

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

NASA Astrophysics Data System (ADS)

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 Cu2+ ions in CuCl2.2H2O, LiCuVO4, CuCl2, and CuBr2 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 Cu2+ ions of Bi2CuO4 and Li2CuO2. 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.

Liu, Jia; Koo, Hyun-Joo; Xiang, Hongjun; Kremer, Reinhard K.; Whangbo, Myung-Hwan

2014-09-01

442

Ion-Exchange Characteristics of a Layered Metal Sulfide for Removal of Sr From Aqueous Solutions  

Microsoft Academic Search

Strontium-90 (Sr) is the most abundant radionuclide in radioactive wastes, and is typically isolated by treatment with an inorganic ion-exchange material. Most inorganic ion-exchange materials contain oxygen. The ion-exchange chemistry of layered metal sulfides is relatively poorly explored compared with that of oxide ion-exchange materials. Here, a layered metal sulfide (UCR-28), constructed from [ZnGe3S9(H2O)] supertetrahedral clusters, was prepared under hydrothermal

Xingliang Li; Bijun Liu; Yuan Jian; Wenbin Zhong; Wanjun Mu; Jiaheng He; Zongping Ma; Guoping Liu; Shunzhong Luo

2012-01-01

443

High-pressure ion-thermal properties of metals from ab initio interatomic potentials  

SciTech Connect

It has recently become possible for the first time to calculate ab initio two-ion and three-ion interatomic potentials in d-electron transition metals. The nature of these potentials for the 3d series metals is discussed. In the case of copper, where three-ion contributions may be neglected, application is made to the ion-thermal component of the equation of state and to the calculation of melting on the shock Hugoniot. 13 refs., 3 figs.

Moriarty, J.A.

1985-06-01

444

Nanoparticles reduce nickel allergy by capturing metal ions  

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

445

Prostate cancer outcome and tissue levels of metal ions  

USGS Publications Warehouse

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.

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

2011-01-01

446

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

SciTech Connect

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.

Aymar, M.; Dulieu, O. [Laboratoire Aime Cotton, CNRS, UPR3321, Ba circumflex t. 505, Univ Paris-Sud, 91405 Orsay Cedex (France); Guerout, R. [Laboratoire Kastler-Brossel, CNRS, ENS, Univ Pierre et Marie Curie case 74, Campus Jussieu, F-75252 Paris Cedex 05 (France)

2011-08-14

447

Ion conics and counterstreaming electrons generated by lower hybrid waves in the earth's magnetosphere  

NASA Technical Reports Server (NTRS)

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.

Chang, Tom; Crew, Geoffrey B.; Retterrer, John M.; Jasperse, John R.

1989-01-01

448

Rare earth hydrides formed by reaction of rare earth metals with water vapor  

NASA Astrophysics Data System (ADS)

The reaction of Pr, Gd, Dy, and Er with water vapor has been studied in the temperature interval 100 to 140°C. There was corroboration of the earlier observations of J. Dexpert-Ghys. et al. ( J. Less Common Metals, 41, 105, 1975) to the effect that (1) DyH 2 forms when Dy is treated with water vapor and (2) there is no evidence by X-ray diffraction of the formation of Dy(OH) 3 and Dy 2O 3. Since the free energy change involved in forming DyH 2 and O 2 from Dy and H 2O is about +17 kcal, the reaction was carried out under radiation in an effort to ascertain whether the missing energy was being photochemically supplied. Results were negative. Mass spectrometric examinations of the reacting system using O 18-enriched water showed no oxygen in the gaseous products. Study of the solid using Auger spectroscopy gave clear indication of large amounts of oxygen in the sample after reaction with water. Presumably the incorporation of oxygen in the lattice permits the thermodynamic requirements to be satisfied. Oxygen is not present in Dy in a phase with sufficient long-range order to give a detectable X-ray diffraction pattern. Pr and Gd in the form of filings react with H 2O to give dihydride and hydroxide. Er is unreactive as judged from X-ray diffraction measurements.

Smith, H. K.; Moldovan, A. G.; Craig, R. S.; Wallace, W. E.; Sankar, S. G.

1980-04-01

449

Peroxide Stress Elicits Adaptive Changes in Bacterial Metal Ion Homeostasis  

PubMed Central

Abstract Exposure to hydrogen peroxide (H2O2) and other reactive oxygen species is a universal feature of life in an aerobic environment. Bacteria express enzymes to detoxify H2O2 and to repair the resulting damage, and their synthesis is typically regulated by redox-sensing transcription factors. The best characterized bacterial peroxide-sensors are Escherichia coli OxyR and Bacillus subtilis PerR. Analysis of their regulons has revealed that, in addition to inducible detoxification enzymes, adaptation to H2O2 is mediated by modifications of metal ion homeostasis. Analogous adaptations appear to be present in other bacteria as here reviewed for Deinococcus radiodurans, Neisseria gonorrhoeae, Streptococcus pyogenes, and Bradyrhizobium japonicum. As a general theme, peroxide stress elicits changes in cytosolic metal distribution with the net effect of reducing the damage caused by reactive ferrous iron. Iron levels are reduced by repression of uptake, sequestration in storage proteins, and incorporation into metalloenzymes. In addition, peroxide-inducible transporters elevate cytosolic levels of Mn(II) and/or Zn(II) that can displace ferrous iron from sensitive targets. Although bacteria differ significantly in the detailed mechanisms employed to modulate cytosolic metal levels, a high Mn:Fe ratio has emerged as one key correlate of reactive oxygen species resistance. Antioxid. Redox Signal. 15, 175–189. PMID:20977351

Faulkner, Melinda J.

2011-01-01

450

Quasi-linear analysis of ion Weibel instability in the earth's neutral sheet  

NASA Technical Reports Server (NTRS)

A quasi-linear analysis of the ion Weibel instability (IWI) for waves with parallel propagation is carried out for parameters appropriate to the earth's neutral sheet during the substorm interval. For ion drift speed reaching sizable fraction of the ion thermal speed, unstable waves grow to a nonlinear regime in a time interval greater than an ion gyroperiod. The saturation level is attained with current density reduced to about 15-28 percent of its preactivity level. The unstable wave amplitude normalized to the initial ambient field is found to be in the range of 0.2-0.8. This is accompanied by ion heating along the magnetic field with the parallel temperature being enhanced by 25-90 percent. Thus, the IWI can provide nonadiabatic heating of ions in current disruptions during substorms. The associated anomalous resistivity is estimated to be about 1 x 10 exp -7 to 1 x 10 exp -6 s, which is about 11 to 12 orders of magnitude above the classical resistivity.

Lui, Anthony T. Y.; Yoon, Peter H.; Chang, Chia-Lie

1993-01-01

451

Investigation of the Transport of Solar Ions Through the Earth's Magnetosphere  

NASA Technical Reports Server (NTRS)

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.

Lennartsson, O. W.; Evans, David (Technical Monitor)

2000-01-01