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1

Spectroscopy and chemical dynamics of weakly bound alkaline-earth metal ion-H and alkaline-earth metal ion-hydrocarbon complexes 2  

Microsoft Academic Search

The activation of hydrocarbon bonds by metal atoms are among the most vital processes in chemistry. This review focuses on the spectroscopy and chemical dynamics of weakly bound alkaline-earth metal ion-H and alkaline-earth metal ion-hydrocarbon bimolecular complexes using mass-resolved photodissociation spectroscopy techniques. The photodissociation spectroscopy of isolated clusters, in concert with translationalenergy spectroscopy of the products, gives unique and detailed

Paul D. Kleiber Jing Chen

1998-01-01

2

Fluorescence Spectroscopy of Polymer Systems Doped with Rare-Earth Metal Ions and Their Complexes  

Microsoft Academic Search

There has been an increased attention to explore the possibility of using polymer materials with rare-earth (RE) metal ions and their complexes as potential optical materials due to their capability of exhibiting novel and unusual properties. The fluorescence characteristics of polymer systems doped with RE metal ions and\\/or their complexes were analyzed and the effects of the doping metal ion\\/metal

K. S. V. Krishna Rao; Hong-Guo Liu; Yong-Ill Lee

2010-01-01

3

Ab initio study of NMR shielding of alkali earth metal ions in water complexes and magnetic moments of alkali earth metal nuclei  

NASA Astrophysics Data System (ADS)

Ab initio calculations of NMR shielding constants of alkali earth metal ions in the series of water clusters are presented. The shielding constants for systems modeling the structure of the solvation layer of these ions are determined by adding to the coupled cluster singles-and-doubles (CCSD) results the calculated relativistic corrections. The relative magnitude of the dynamical effects, estimated for a typical solvated ion from Car-Parrinello molecular dynamics, is very small. The computed shielding constants are used next to obtain new values of the nuclear magnetic dipole moments of alkali earth metal nuclei.

Antušek, Andrej; Rodziewicz, Pawel; Ke?ziera, Dariusz; Kaczmarek-Ke?ziera, Anna; Jaszu?ski, Micha?

2013-11-01

4

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

5

Complex formation of p-nitrocalix[6]arene with rare earth metal ions.  

PubMed

p-Nitrocalix[6]arene (CALX-N6, L) formed a 1:1 metal complex, ML, with light rare earth metal ions (M3+), such as La3+, Pr3+ and Nd3+ except Ce3+, but formed a 1:2 (M(3+):L) complex, ML2 (the charge of the complex is omitted) with heavy rare earth metal ions, such as Sm(3+)-Lu3+ including Y3+. The conditional stability constants of these 1:1 and 1:2 complexes, KML and KML2, were measured by a ligand displacement method using absorption spectrophotometry in 4% (v/v) acetone aqueous solution at pH 9.65 +/- 0.15 and 25 degrees C. PMID:16733323

Kajiwara, Makiko; Koga, Masayoshi; Nishida, Masashi; Yoshida, Isao

2006-03-01

6

Ion bombardment of materials containing alkali metals of alkaline earths  

Microsoft Academic Search

Experiments show that argon ion bombardment of many substances results in the chemical sensitization of the irradiated surface. As a consequence, subsequent exposure to atmospheric water vapor causes evolution of hydrogen, and in certain cases leads to severe surface corrosion. The effect occurs on targets containing elements from the first and second column of the periodic table, and therefore includes

E. H. Hirsch; T. R. Adams

1978-01-01

7

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

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

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

NASA Astrophysics Data System (ADS)

Sol-gel derived organic-inorganic hybrid materials doped with rare earth metal ions (Pr 3+) and small amounts of lithium ions (˜0.1-0.2 wt.%) were produced from the tetraethyl orthosilicate (TEOS), AlCl 3·6H 2O (about 10 mol%), ethyl methacrylate, butyl methacrylate and some other organic additions (ca. 35-40 wt.% of organics in the fresh gels) to obtain hybrid organic-inorganic hosts. The gel and hybrid materials obtained were aged at room temperature for three weeks, then heated in an electric drier for 3 h at temperature of 125 °C and investigated for morphology, structure and luminescence properties by X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), 29Si and 27Al MAS nuclear magnetic resonance and fluorescence spectroscopy. An influence of the organic additions and inorganic dopants on microstructure of the materials obtained and their luminescence properties has been examined. Under excitation with UV radiation in a range of ˜210-350 nm, the sharp and relatively intense luminescence emission lines due to 3P 0 ? 3H 4 (blue) and 3P 0 ? 3F 3 (red) transitions of Pr 3+ ions were observed in the luminescence spectra of gel and hybrid materials of SA-series.

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

2011-10-01

10

Co-doping of glasses with rare earth ions and metallic nanoparticles for frequency up-conversion  

Microsoft Academic Search

We explore different approaches to achieve co-doping of glasses with rare earth ions and metallic nanoparticles, and to manipulate the spectral position of the particles' surface plasmon resonance. The final goal is to find a composite material with improved efficiency of frequency up-conversion of light for photovoltaic applications. The potential for improvement has been shown by theoretical calculations predicting that

S. Wackerow; G. Seifert

2010-01-01

11

COMPLEXATION STUDIES OF ALKALINE EARTH METAL IONS WITH MACROCYCLIC LIGANDS OF THE ANTHRAQUINONE-CROWN ETHER TYPE BY ELECTROCHEMICAL METHODS  

Microsoft Academic Search

The electrochemical and complexation behaviour of synthetic ligands of the crown ether type attached to an anthraquinone unit has been studied using cyclic voltammetry. In the presence of alkaline earth metal ions the positions and type of the ligand redox waves were changed and the potentials of the respective redox couples were shifted to more positive values. These shifts in

J. M. Caridade Costa; D. Bethell

1999-01-01

12

COMPLEXATION STUDIES OF ALKALINE EARTH METAL IONS WITH MACROCYCLIC LIGANDS OF THE ANTHRAQUINONE-CROWN ETHER TYPE BY ELECTROCHEMICAL METHODS  

Microsoft Academic Search

The electrochemical and complexation behaviour of synthetic ligands of the crown ether type attached to an anthraquinone unit has been studied using cyclic voltammetry. In the presence of alkaline earth metal ions the positions and type of the ligand redox waves were changed and the potentials of the respective redox couples were shifted to more positive values. These shifts in

J. M. Caridade Costa; D. Bethell

1998-01-01

13

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

14

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

15

Selectivity Study of Alkaline Earth and Divalent Transition Metal Ions on [Al + Na]-Substituted Tobermorites  

Microsoft Academic Search

The ion-exchange selectivities of [Al + Na]-substituted tobermorites with 1–20 mol% substitution of aluminum for silicon at low loadings were investigated for Mg, Sr, Ba, and Ni. The selectivity order depended on the degree of substitution, exchanging medium, and loading of metal ions, reflecting different types of ion-exchange sites in the Al-substituted tobermorites which are an interesting group of calcium

Masamichi Tsuji; Sridhar Komarneni

1993-01-01

16

Complex formation between azacrown derivatives of dibenzylidenecyclopentanone and alkali-earth metal ions  

Microsoft Academic Search

The complex formation of 2,5-bis[4-(1,7,10,13-tetraoxa-4-azacyclopentadec-4-yl)benzylidene]cyclopentanone and several model compounds, prospective metal-sensitive fluorescent probes, with Mg2+, Ca2+, and Ba2+ ions in acetonitrile was studied. The azacrown derivatives of dibenzylidenecyclopentanone have two complex formation centers, azacrown cycle and carbonyl group. The sequence of binding to these sites is different for different ions. The efficient ejection of the Ca2+ and Ba2+ ions from

A. O. Doroshenko; A. V. Grigorovich; E. A. Posokhov; V. G. Pivovarenko; A. P. Demchenko; A. D. Sheiko

2001-01-01

17

Zeta Potential of Kaolinite in the Presence of Alkali, Alkaline Earth and Hydrolyzable Metal Ions  

Microsoft Academic Search

Electrokinetic remediation is one of the promising subsurface clean up techniques whose efficiency is directly affected by the zeta potential of clay minerals. To determine the factors affecting the zeta potential, in turn, electrokinetic remediation, the zeta potential of kaolinite is determined usingelectrophoretic mobility in the salt and heavy metals ions asfunctions of pH and concentration. The zeta potential of

Yeliz Yukselen; Abidin Kaya

2003-01-01

18

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

19

Hyperfine structures of Ca+ and Sr+ ions: Summary of trends in hyperfine interactions in the alkaline-earth-metal ions and corresponding series with similar electronic structures  

Microsoft Academic Search

The hyperfine interactions in the alkaline-earth-metal ions, Ca+ and Sr+, have been investigated using the relativistic linked-cluster many-body perturbation theory (RLCMBPT). The calculated theoretical hyperfine fields are found to be 135.3 and 266.3 T for Ca+ and Sr+, respectively, in good agreement with the experimentally obtained values of 139.0 T for Ca+ and 267.2 T for Sr+. The contributions from

Xing Yuan; S. N. Panigrahy; R. W. Dougherty; T. P. Das; J. Andriessen

1995-01-01

20

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

21

Sensitized Fluorescence of Rare Earth Ions in Crystals.  

National Technical Information Service (NTIS)

In order to improve the efficiency of optically pumped crystalline laser materials, a search was conducted to discover combinations of crystalline hosts, rare earth ions, and transition metal ions in which the transition metal ions are able to absorb radi...

R. C. Ohlmann N. T. Melamed R. Mazelsky W. E. Kramer

1967-01-01

22

Spin-Orbit Qubits of Rare-Earth-Metal Ions in Axially Symmetric Crystal Fields  

NASA Astrophysics Data System (ADS)

Contrary to the well-known spin qubits, rare-earth-metal qubits are characterized by a strong influence of crystal field due to large spin-orbit coupling. At low temperature and in the presence of resonance microwaves, it is the magnetic moment of the crystal-field ground state which nutates (for several ?s) and the Rabi frequency ?R is anisotropic. Here, we present a study of the variations of ?R(H?0) with the magnitude and direction of the static magnetic field H?0 for the odd Er167 isotope in a single crystal CaWO4:Er3+. The hyperfine interactions split the ?R(H?0) curve into eight different curves which are fitted numerically and described analytically. These “spin-orbit qubits” should allow detailed studies of decoherence mechanisms which become relevant at high temperature and open new ways for qubit addressing using properly oriented magnetic fields.

Bertaina, S.; Shim, J. H.; Gambarelli, S.; Malkin, B. Z.; Barbara, B.

2009-11-01

23

Complexation of metal ions, including alkali-earth and lanthanide(III) ions, in aqueous solution by the ligand 2,2',6',2''-terpyridyl.  

PubMed

Some metal-ion-complexing properties of the ligand 2,2',6',2''-terpyridyl (terpy) in aqueous solution are determined by following the ?-?* transitions of 2 × 10(-5) M terpy by UV-visible spectroscopy. It is found that terpy forms precipitates when present as the neutral ligand above pH ?5, in the presence of electrolytes such as NaClO(4) or NaCl added to control the ionic strength, as evidenced by large light-scattering peaks. The protonation constants of terpy are thus determined at the ionic strength (?) = 0 to avoid precipitation and found to be 4.32(3) and 3.27(3). The log K(1) values were determined for terpy with alkali-earth metal ions Mg(II), Ca(II), Sr(II), and Ba(II) and Ln(III) (Ln = lanthanide) ions La(III), Gd(III), and Lu(III) by titration of 2 × 10(-5) M free terpy at pH >5.0 with solutions of the metal ion. Log K(1)(terpy) was determined for Zn(II), Cd(II), and Pb(II) by following the competition between the metal ions and protons as a function of the pH. Complex formation for all of these metal ions was accompanied by marked sharpening of the broad ?-?* transitions of free terpy, which was attributed to complex formation affecting ligand vibrations, which in the free ligand are coupled to the ?-?* transitions and thus broaden them. It is shown that log K(1)(terpy) for a wide variety of metal ions correlates well with log K(1)(NH(3)) values for the metal ions. The latter include both experimental log K(1)(NH(3)) values and log K(1)(NH(3)) values predicted previously by density functional theory calculation. The structure of [Ni(terpy)(2)][Ni(CN)(4)]·CH(3)CH(2)OH·H(2)O (1) is reported as follows: triclinic, P1, a = 8.644(3) Å, b = 9.840(3) Å, c = 20.162(6) Å, ? = 97.355(5)°, ? = 97.100(5)°, ? = 98.606(5)°, V = 1663.8(9) Å(3), Z = 4, and final R = 0.0319. The two Ni-N bonds to the central N donors of the terpy ligands in 1 average 1.990(2) Å, while the four peripheral Ni-N bonds average 2.107(10) Å. This difference in the M-N bond length for terpy complexes is typical of the complexes of smaller metal ions, while for larger metal ions, the difference is reversed. The significance of the metal-ion size dependence of the selectivity of polypyridyl ligands, and the greater rigidity of ligands based on aromatic groups such as pyridyl groups, is discussed. PMID:21366261

Hamilton, Joanna M; Anhorn, Michael J; Oscarson, Karen A; Reibenspies, Joseph H; Hancock, Robert D

2011-04-01

24

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

25

1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange  

NASA Astrophysics Data System (ADS)

The location of extraframework cations in Sr2+ and Ba2+ ion-exchanged SAPO-34 was estimated by means of 1H and 23Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium.

Arévalo-Hidalgo, Ana G.; Dugar, Sneha; Fu, Riqiang; Hernández-Maldonado, Arturo J.

2012-07-01

26

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

27

Conductometric and microcalorimetric analysis of the alkaline-earth\\/alkali-metal ion exchange onto polyacrylic acid  

Microsoft Academic Search

The specificity of the exchange between divalent (Di2+?=?Ca2+ or Ba2+) and monovalent (M+?=?Li+, Na+ or K+) ions onto a polyacrylic chain is examined using conductometric and microcalorimetric techniques. Assuming the formation\\u000a of a bidentate complex between the Di2+ and the carboxylate groups, the conductometric data give the exchange ratio (Di2+\\/M+) and the speciation of the acrylic groups. No significant difference

I. Pochard; A. Foissy; P. Couchot

1999-01-01

28

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

29

SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS XXXIX. SYNTHESIS OF TITANIUM(IV) ANTIMONATES AND THEIR ION EXCHANGE PROPERTIES FOR ALKALI AND ALKALINE EARTH METAL IONS  

Microsoft Academic Search

Titanium antimonate (TiSbA) cation exchanger, prepared under different molar ratios of titanium and antimony, has been characterized by X-ray diffraction, thermal analysis, infrared spectra, and pH-titration. The pH-titration curves showed apparently monobasic acid type. The uptakes of alkali metal ions increased with increasing pH of the solution and with decreasing the molar ratio (Ti\\/Sb) in the exchanger. An unusual selectivity

M. Abe; R. Chitrakar; M. Tsuji; K. Fukumoto

1985-01-01

30

Gas-Phase Reactions of hydrated alkaline earth metal ions, M 2+ (H 2 O) n (M = Mg, Ca, Sr, Ba and n = 4–7), with benzene  

Microsoft Academic Search

Gas-phase reactions of hydrated divalent alkaline earth metal ions and benzene were investigated by electrospray ionization\\u000a Fourier-transform mass spectrometry. Rate constants for solvent-exchange reactions were determined as a function of hydration\\u000a extent for Mg2+, Ca2+, Sr2+, and Ba2+ clusters containing four to seven water molecules each. All of the strontium and barium clusters react quickly with benzene.\\u000a Barium reacts slightly

Sandra E. Rodriguez-Cruz; Evan R. Williams

2001-01-01

31

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

32

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

33

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

34

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

NASA Astrophysics Data System (ADS)

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, the theoretical separation factors ? (NaCl/MgCl 2) and ? (NaCl/ZnCl 2) being 43 and 20. Rare earth metal chlorides LnCl 3 with Ln being La, Ce, Pr and Sm and the related YCl 3 were strongly rejected from the membrane, the theoretical separation factors ? (NaCl/LaCl 3) and ? (NaCl/YCl 3) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane.

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

2005-06-01

35

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

36

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

37

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

38

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

39

Electrotransport of Solutes in Rare Earth Metals.  

National Technical Information Service (NTIS)

A review of research on electrotransport in solid rare earth metals is presented. Information and data are included on principles of electrotransport, transport parameters for solutes in rare earth metals, and rare earth purification. (ERA citation 01:026...

O. N. Carlson F. A. Schmidt

1976-01-01

40

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

41

Metal Ion Sources for Ion Beam Implantation  

SciTech Connect

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

Zhao, W. J.; Zhao, Z. Q.; Ren, X. T. [Institute of Heavy Ion Physics and State Key Labarotary in Nuclear Physics and Nuclear Technology, Peking University, Beijing 100871 (China)

2008-11-03

42

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

43

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

44

Divalent Rare-Earth Ions in Optical Maser Materials.  

National Technical Information Service (NTIS)

The report concentrates primarily upon the systems BaClF:Ln2+ and ABF3:Ln2+ (where A = alkali-metal ion, and B = alkaline-earth ion), those compounds selected as best suited to our objectives. The problems were in three major categories: reduction of the ...

G. J. Goldsmith H. L. Pinch

1965-01-01

45

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

46

Photodynamic properties of hypocrellin A, complexes with rare Earth trivalent ions: role of the excited state energies of the metal ions.  

PubMed

Fifteen complexes of hypocrellin A (HA) with rare earth trivalent ions (except Pm3+) along with the complex of HA with Sc3+ were prepared, and their photodynamic activities, including absorption in the phototherapeutic window (600-900 nm); water-solubility; triplet lifetime; generation of reactive oxygen species (ROS), such as singlet oxygen (1O2), superoxide anion radical (O2-*), and hydroxyl radical (OH*); generation of semiquinone anion radical; and affinity to DNA, as well as photosensitized damage on calf thymus DNA (CT DNA), were compared in detail using the UV-visible spectrum, fluorescence spectrum, spin-trapping EPR technique, and laser photolysis technique. All complexes exhibit a red-shifted absorption spectrum, an increased absorbance above 600 nm, improved water solubility, and an enhanced affinity to CT DNA over the parent HA. For ions that possess low-energy excited states, including Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+, the corresponding complexes show undetectable or nearly undetectable fluorescence, a triplet excited-state lifetime, generation of ROS, and photodamage in CT DNA. In contrast, for ions that do not possess low-energy excited states, including Sc3+, Y3+, La3+, Gd3+, and Lu3+, the corresponding complexes exhibit higher photodamage abilities with CT DNA with respect to HA, benefitting from both their comparable or even higher 1O2 quantum yields and an electrostatic affinity that is higher for DNA than HA. PMID:17315917

Zeng, Zhanghua; Zhou, Jiahong; Zhang, Yan; Qiao, Rui; Xia, Shengqin; Chen, Jinrong; Wang, Xuesong; Zhang, Baowen

2007-03-15

47

Optical Properties of Rare Earth Metals.  

National Technical Information Service (NTIS)

The optical properties of rare earth metals are reviewed, especially the heavier rare earths. An introduction to optical properties and measurement methods is followed by a discussion of some errors which can arise because of sample properties, errors whi...

D. W. Lynch

1977-01-01

48

Equilibria and heats of exchange of alkaline-earth metal ions on the Na form of mordenite  

Microsoft Academic Search

Sorption-analytic studies of ion exchange equilibria combined with direct calorimetric measurements of the heats of ion exchange\\u000a sorption of the Ca2+, Sr2+, and Ba2+ cations were performed over the whole range of solid phase fillings with sorbed cations on the Na forms of two mordenites\\u000a prepared from natural specimens rich in Na+ and Ca2+ cations. Ion exchange constants were determined

Yu. I. Tarasevich; V. E. Polyakov; D. A. Krysenko

2010-01-01

49

Metal ion release from metal implants  

Microsoft Academic Search

Metal ion release from metallic materials, e.g. stainless steel, cobalt–chromium alloy, titanium, and titanium alloys, implanted into human body was reviewed in this paper. Surface oxide films on metallic materials play an important role as an inhibitor of ion release and they change with the release in vivo. Low concentration of dissolved oxygen, inorganic ions, proteins, and cells may accelerate

T. Hanawa

2004-01-01

50

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

51

Comet Encke: Meteor metallic ion identification by mass spectrometer  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

52

Electropolishing the Rare-Earth Metals.  

National Technical Information Service (NTIS)

This paper describes a method whereby the rare-earth metals can be consistently electropolished and chemically etched. The method involves cooling an alcohol-perchloric electrolyte to -76 deg C before electropolishing. The metals are chemically polished i...

D. T. Peterson E. N. Hopkins

1964-01-01

53

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

54

Zone Refining of Rare Earth Metals. II.  

National Technical Information Service (NTIS)

In work reported at the 13th Rare Earth Conference, zone melting was shown to move impurities in commercial purity rare earth metals. The interstitial impurities O and N moved in the opposite direction from the zone while metallic impurities moved with th...

D. Fort B. J. Beaudry D. W. Jones K. A. Gschneidner

1979-01-01

55

Thermal Emission Properties of Rare Earth Metals.  

National Technical Information Service (NTIS)

The work functions of a number of rare earth metals have been calculated from data of experimental sputtering of rare earth metals of high purity onto a tungsten or rhenium substrate through an anode slit in a vacuum tube. The work functions appear to cha...

O. K. Kultashev S. E. Rozhkov

1974-01-01

56

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

57

Coordination chemistry of the alkaline earth metal ions with Zwitterionic forms of the Schift bases. X-Ray studies and other spectroscopic properties  

NASA Astrophysics Data System (ADS)

The non-ionized forms of tetradentate Schiff bases NN'-ethylenebis(salicylideneimine), H 2L and NN'-propane-1,3-diylbis(salicylideneimine), H 2L' react with hydrated alkaline earth halide and nitrate to give complexes of the type: M(H 2L)Cl 2· nH 2O [M = Mg(II), Ca(II), Sr(II); n = 0-4], M(H 2L) 2Cl 2 [M = Ca(II), Sr(II), M(H 2L) nBr 2 [M = Ca(II), Sr(II); n = 2, 3 and Mg 2(H 2L) 3Br 4], M(H 2L) nI 2 [M = Mg(II), Ca(II), Sr(II), Ba(II); n = 2, 3)], M(H 2L) n(NO 3) 2 and M(H 2L') n(NO 1) 2[M = Mg(II), Ca(II); n = 1, 2)]. Because of distinct spectral similarities with structurally known Ca(H 2L')(NO 3) 2 compound, the Schiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups, which carry the protons transferred from phenolic groups on complexation. Halide and nitrate are coordinated to the central metal ion except in 2:1 nitrato complexes where the presence of both ionic and coordinated nitrate groups are evident and also in 3:1 halide complexes where the presence of non-coordinated halide cannot be excluded. X-Ray powder photographs showed no marked similarities between Ca(H 2L')(NO 3) 2 and Mg(H 2L')(NO 3) 2 while there are some isomorphic features between the same types of halide complexes. Infrared spectra and other structural information revealed the polymeric nature of the complexes. Therefore the coordination numbers exhibited by the alkaline earth metal cations would be 4, 6 or 8 in these series of Schiff base complexes.

Tajmir-Riahi, H. A.; Lotfipoor, M.

58

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

PubMed

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

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

2010-08-30

59

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

60

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

DOEpatents

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

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

1995-08-01

61

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

DOEpatents

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

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

1995-08-01

62

From alkaline earth ion aggregates via transition metal coordination polymer networks towards heterometallic single source precursors for oxidic materials.  

PubMed

Heterometallic oxides are used as materials in many applications, e.g. from ferroelectrics to superconductors. Making these compounds usually requires high temperatures and long reaction times. Molecular precursors may contribute to render their processing shorter and accessible at lower temperatures, thus cheaper in energy and time. In this review article, different approaches toward oxide materials will be shown, starting with homometallic clusters and coordination polymers and highlighting recent results with heterometallic single source precursors. On the way to the latter, we came across many exciting results which themselves allowed applications in different fields. This work will give an overview on how these fields were brought together for the current mixed metallic compounds as precursors for heterometallic oxides. PMID:21138074

Gschwind, Fabienne; Crochet, Aurélien; Maudez, William; Fromm, Katharina M

2010-01-01

63

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

SciTech Connect

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

Arevalo-Hidalgo, Ana G. [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico); Dugar, Sneha; Fu, Riqiang [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Hernandez-Maldonado, Arturo J., E-mail: arturoj.hernandez@upr.edu [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico)

2012-07-15

64

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

NASA Astrophysics Data System (ADS)

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 289 nm and there was no significant change in the presence of Sc 3+, La 3+, Pr 3+, Sm 3+, Gd 3+, Tb 3+, Yb 3+ and Lu 3+ except for Ce 3+ and Eu 3+. 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 Sc 3+, La 3+, Pr 3+, Sm 3+, Gd 3+, Tb 3+, Yb 3+ and Lu 3+ leads to an increase in fluorescence intensity of A18C6-Ox, while Ce 3+ and Eu 3+ 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.

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

2011-01-01

65

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

66

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

67

Intermultiplet Transitions in Rare-Earth Metals.  

National Technical Information Service (NTIS)

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 t...

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

1985-01-01

68

Advances in metal ion sources  

SciTech Connect

Beams of metallic ion species can be produced by the ECR (electron cyclotron resonance) ion source and by the MEVVA (metal vapor vacuum arc) ion source. Although the ECR source is fundamentally a gaseous ion source, metal ion beams can be produced by introducing metallic feed material into the plasma discharge using a number of techniques. The ion charge states can be very high, which is a significant advantage to most applications. The MEVVA ion source, on the other hand, is specifically a metal ion source. It has produced metallic ion beams from virtually all the solid metallic elements at a current of typically hundreds of milliamperes; the ions produced are in general multiply ionized, but not as highly stripped as those generated in the ECR source. Although the MEVVA source at present operates in a pulsed mode with a low duty cycle (less than or equal to 1%), work is in progress to increase the duty cycle significantly. In this paper the operation and performance of the LBL ECR and MEVVA ion sources, with respect to metal ion generation, are described.

Brown, I.G.

1988-05-01

69

Ion beam modification of metals  

Microsoft Academic Search

Energetic ions beams may be used in various ways to modify and so improve the tribological properties of metals. These methods include: - ion implantation of selected additive species; - ion beam mixing of thin deposited coatings; - ion-beam-assisted deposition of thicker overlay coatings. The first of these techniques has been widely used to modify the electronic properties of semiconductors,

G. Dearnaley

1990-01-01

70

Simultaneous determination of alkali and alkaline earth metals by ion chromatography with neutral carrier-based ion-selective electrode detector  

Microsoft Academic Search

Neutral carrier-based potentiometric detectors that can monitor both mono- and divalent cations have been developed for ion chromatography. The solvent polymeric membranes doped with a mixture of monesin methyl ester (MME; a monovalent cation-selective ionophore) and a divalent cation-selective ionophore (ETH 1117 or ETH 4030) have the combined properties of each single ionophore. These double ionophore-doped ISE membranes showed similar

Uk Sun Hong; Hye Kyong Kwon; Hakhyun Nam; Geun Sig Cha; Kyung-Hee Kwon; Ki-Jung Paeng

1995-01-01

71

Electron Interaction in Rare-Earth Metals.  

National Technical Information Service (NTIS)

The paper contains a discussion of various aspects of the s-f(s-d) exchange interaction in the ferromagnetically spin-ordered states of rare-earth metals such as (1) the indirect Ruderman-Kittel-Kasuya-Yosida-type exchange interaction between localized 4f...

D. J. Kim

1968-01-01

72

Paramagnetic Resonance in Rare Earth Metals.  

National Technical Information Service (NTIS)

Apparatus for the observation of spin wave resonance (SWR) in rare earth metal films in magnetic fields of 27 Koe and at liquid nitrogen temperatures was developed. Although SWR was observed in evaporated iron and nickel films none has been observed in ga...

R. S. Tebble A. M. Harris B. Johnson D. W. Temple

1967-01-01

73

Aluminophosphate-doped glasses with rare-earth ions  

Microsoft Academic Search

Aluminophosphate glasses doped with rare-earth ions have recently attracted a large interest owing to their relevant non-linear optical properties. Until now, all studies were done over the glasses doped with rare-earth ions, in which the rare-earth ions were into a vitreous silica matrix. Our study was made as for rare-earth ions into a vitreous aluminophosphate matrix. In the first step,

Rodica Rogojan; Paul E. Sterian; Mihai Elisa

2000-01-01

74

Synthesis, structure and reactivity of rare-earth metal complexes containing anionic phosphorus ligands.  

PubMed

A comprehensive review of structurally characterized rare-earth metal complexes containing anionic phosphorus ligands is presented. Since rare-earth elements form hard ions and phosphorus is considered as a soft ligand, the rare-earth metal phosphorus coordination is regarded as a less favorite combination. Three classes of phosphorus ligands, (1) the monoanionic organophosphide ligands (PR2(-)) bearing one negative charge on the phosphorus atom; (2) the dianionic phosphinidene (PR(2-)) and P(3-) ligands; and (3) the pure inorganic polyphosphide ligands (Pn(x-)), are included here. Particular attention has been paid to the synthesis, structure, and reactivity of the rare-earth metal phosphides. PMID:23945727

Li, Tianshu; Kaercher, Sabrina; Roesky, Peter W

2014-01-01

75

Luminescence properties of B2O3-GeO2-Gd2O3 scintillating glass doped with rare-earth and transition-metal ions  

NASA Astrophysics Data System (ADS)

Novel B2O3-GeO2-Gd2O3 ternary scintillating glasses doped with 1 mol% rare-earth and transition-metal activators were synthesized by melt-quenching method. Their transmittance, photoluminescence (PL) and X-ray excited luminescence (XEL) spectra were investigated. The results suggest that a high content of Gd2O3 is of significance for designing dense glass with density of 6.0 g/cm3. And energy transfer from Gd3+ to the incorporated activators can be realized in the borogermanate glasses. The emission position and decay time can be efficiently tuned by incorporating various kinds of activators. All results imply the developed borogermanate scintillating glass is potential for scintillating fields.

Sun, Xin-Yuan; Jiang, Da-Guo; Wang, Wen-Feng; Cao, Chun-Yan; Li, Yu-Nong; Zhen, Guo-Tai; Wang, Hong; Yang, Xin-Xin; Chen, Hao-Hong; Zhang, Zhi-Jun; Zhao, Jing-Tai

2013-07-01

76

Rare earth element complexation by carbonate and oxalate ions  

NASA Astrophysics Data System (ADS)

Rare earth carbonate and oxalate complexation constants have been determined through ex-amination of distribution equilibria between tributyl phosphate and an aqueous perchlorate phase. Carbonate complexation constants appropriate to the REE in seawater (25°C, 35%., 1 atm) can be described in terms of atomic number, Z. nlog sw?1 = 4.853 + 0.1135( Z - 57) - 0.003643( Z - 57) 2log sw?2 = 80.197 + 0.1730( Z - 57) - 0.002714( Z -57) 2 where sw? 1 = [MCO +3] /[M 3+][CO 2-3] T, sw? 2 = [M(CO 3) -3] /[M 3+][CO 2-3] 2' T [ M3+] is an uncomplexed rare earth concentration in seawater, [ MCO+3] and [ M( CO-3) 2] are carbonate complex concentrations, and [CO 2-3] T is the total (free plus ion paired) carbonate ion concentration in seawater (molal scale). Our analyses indicate that in seawater with a total carbonate ion concentration of 1.39 × 10 -4 moles/Kg H 2O, carbonate complexes for the lightest rare earth, La, constitute 86% of the total metal, 7% is free La 3+ and the remaining 7% exists as hydroxide, sulfate, chloride and fluoride complexes. For Lu, the heaviest rare earth, carbonate complexes are 98% of the total metal, 0.3% is uncomplexed and 1.5% is complexed with hydroxide, sulfate, chloride and fluoride. Oxalate and carbonate constants are linearly correlated. This correlation appears to be quite useful for estimating trivalent metal-arbonate stability constants from their respective oxalate stability constants.

Cantrell, Kirk J.; Byrne, Robert H.

1987-03-01

77

Rare earth transition metal sulfides, LnMS 3  

NASA Astrophysics Data System (ADS)

Ternary rare earth transition metal sulfides LnMS 3 with Ln = La, Nd, and Gd, and M = V and Cr; as well as Ln = La and M = Mn, Fe, Co, and Ni have been prepared and characterized. The vanadium and chromium sulfides crystallize in a monoclinic layer structure isotypic with LaCrS 3, while the other LnMS 3 sulfides crystallize in a hexagonal structure. Chemical shifts of the metal K-absorption edge and XPS binding energies of core levels indicate that the transition metal is trivalent in the V and Cr sulfides, while it is divalent in the Mn, Fe, Co, and Ni sulfides. Electrical and magnetic properties of the sulfides are discussed in terms of their structures and the electronic configurations of the transition metal ions.

Murugesan, T.; Ramesh, S.; Gopalakrishnan, J.; Rao, C. N. R.

1981-07-01

78

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

79

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

80

Non-metal-to-metal transition in alkaline earth monolayers  

NASA Astrophysics Data System (ADS)

The non-metal-to-metal transition (NMT) in alkaline earth (AE) adsorbed films on increasing coverage is simulated by the film linearized augmented plane wave (LAPW) calculations of the electronic structure of hexagonal AE monolayers for various lattice periods. For low density of films, the absolute gap at the Fermi energy reveals a non-metallic state. As the density increases, the band hybridization makes the gap close, thus performing the metallization of the monolayers. The NMT is found to be of abrupt character, while the critical lattice period depends on the particular AE element. A qualitative relation between the calculated evolution of electronic structure for AE monolayers and experimental ultraviolet photoelectron spectroscopy (UPS) and low-energy electron loss spectroscopy (LEELS) data on the NMT in AE films adsorbed on transition metal surfaces is discussed in the framework of estimated dielectric function.

Yakovkin, I. N.

1999-12-01

81

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

82

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

83

Corrosion behaviour of rare earth ion-implanted hot-dip galvanised steel  

Microsoft Academic Search

The corrosion and oxidation behaviour of many metallic materials can be modified by ion beam bombardment of their top surface layers. Mechanical and chemical mechanisms co-operate to prevent the progress of corrosion. Rare earth ions have already been employed to avoid high-temperature oxidation of stainless steels and other technological alloys. This paper extends the use of lanthanides to improve the

M. A Arenas; J. J de Damborenea; A Medrano; J.-A Garc??a; R Rodr??guez

2002-01-01

84

Ion beam modification of metals  

NASA Astrophysics Data System (ADS)

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

Dearnaley, G.

1990-04-01

85

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

86

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

87

Mechanistic Enzyme Models: Pyridoxal and Metal Ions.  

ERIC Educational Resources Information Center

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

Hamilton, S. E.; And Others

1984-01-01

88

Photophysical properties of metal ion functionalized NaY zeolite.  

PubMed

A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu(3+), Tb(3+), Ce(3+), Y(3+), Zn(2+), Cd(2+), Cu(2+)) exchanged zeolite, rare-earth ion (Eu(3+), Tb(3+), Ce(3+)) exchanged zeolite modified with Y(3+) and rare-earth ion (Eu(3+), Tb(3+), Ce(3+)) exchanged zeolite modified with Zn(2+) are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare-earth ion broadens the application of zeolite as a luminescent host. The Eu(3+) ion exchanged zeolite shows white light luminescence with a great application value and Ce(3+) exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite. PMID:24392790

Duan, Tian-Wei; Yan, Bing

2014-01-01

89

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

90

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

91

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

92

Research on determination of the rare-earth content in metal phases of steel  

NASA Astrophysics Data System (ADS)

The behavior of the rare-earth dissolved in a-Fe, of the iron-cerium intermetallic compounds and of the rare-earth inclusions in electrolytic separation process has been studied by means of counting measurements of radioactivity, the electron probe, and X-ray analysis. The experimental results show that the rare-earth sulfide and the rare-earth oxide are stable completely in the electrolytic separation process, when the composition of the electrolytic solution is 1 pct 4-methyl ammonium chloride, 5 pct triethanolamine, 5 pct glycerin, and 89 pct methyl alcohol, and the controlling anode current density is ?100 mA/cm2. But Fe-Ce intermetallic compounds and the rare-earth dissolved in a-Fe enter into electrolytic solution as ions. When the cerium ion concentration in electrolytic solution is >7.87 X 10-5 mol/liter electrolyte, precipitates of cerium hydroxide will be formed. When the inclusions are separated quantitatively, the electrolytic solution must be filtered by using a funnel with filter paper pulp thick up to 6 mm, and not be filtered directly with single filter paper. Samples without rare-earth were remelted and a radioactive isotope141Ce was added to the steel. Inclusions were separated by the electrolytic method in the nonaqueous solution. The counting of 14lCe in the electrolytic solution was measured. Thus the rare-earth content in the metal phases can be calculated. Experimental results show that the rare-earth content in the metal phases increases with the total rare-earth content in steel. The rare-earth content in the metal phases of the steel was also found to increase as the aluminum content in steel was increased. This method for determining the rare-earth content in the metal phases of steel is very sensitive. The sensitivity is 10-6 pct.

Keming, Fang; Ruiming, Ni

1986-02-01

93

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

94

A complexometric method for the determination of small amounts of an alkaline-earth metal in mixture with other metals.  

PubMed

A discussion of the conditions for the complexometric determination of the minor component in a mixture of two metal ions is presented. It is based on expressions of the Ringbom type for the titration error. These are derived by the use of logarithmic diagrams. The results have been used to devise an analytical procedure for the determination of the alkaline earth metals in the presence of a large excess of nickel or zinc. PMID:18962630

Johansson, E; Olin, A

1980-02-01

95

N-(4-amino-7-nitrobenzaoxa-1,3-diazole)-substituted aza crown ethers: complexation with alkali, alkaline earth metal ions and ammonium  

PubMed Central

Three novel aza-crown ether derivatives incorporating 4-amino-7-nitrobenzaoxa-1,3-diazole (NBD) chromophore were synthesized and their structure confirmed by 1H-NMR, IR and elemental analysis. The influence of the solvent polarity and protonation on the photophysical properties of NBD-15-crown-5 was studied by UV/Vis and fluorescence methods. The influence of the investigated cations on the absorption spectra of the ligands was negligible, however emission was strongly affected. Complexation and binding stability of NBD-aza-15-crown-5 and NBD-aza-18-crown-6 were studied using fluorescence spectroscopy. NBD-aza-18-crown-6 exhibits strong selectivity toward Ca2+ and Sr2+ ions with formation constants about 103 times higher than the formation constants with the other ions included in the study.

Deiab, Shihab D.; Archibong, Edikan E.; Jackson, Mercedes; Mochona, Bereket; Gangapuram, Madhavi; Redda, Kinfe K.

2011-01-01

96

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

Code of Federal Regulations, 2010 CFR

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

2011-07-01

97

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

Code of Federal Regulations, 2010 CFR

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

2012-07-01

98

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

Code of Federal Regulations, 2010 CFR

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

2002-07-01

99

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

Code of Federal Regulations, 2010 CFR

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

1996-07-01

100

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

Code of Federal Regulations, 2010 CFR

...SOURCE CATEGORY] [Subpart Y - Primary Rare Earth Metals Subcategory] [Sec. 421...Applicability: Description of the primary rare earth metals subcategory.] 40 PROTECTION...MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory Sec....

1996-07-01

101

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

Code of Federal Regulations, 2010 CFR

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

2000-07-01

102

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

Code of Federal Regulations, 2010 CFR

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

2003-07-01

103

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

Code of Federal Regulations, 2010 CFR

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

2001-07-01

104

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

Code of Federal Regulations, 2010 CFR

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

1998-07-01

105

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

106

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

107

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

108

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

109

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

Code of Federal Regulations, 2012 CFR

... false Hydrated alkaline earth metal salts of metalloid oxyanions. 721.4668...4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a) Chemical...identified as hydrated alkaline earth metal salts of metalloid oxyanions (PMN...

2012-07-01

110

Weak alkali and alkaline earth metal complexes of low molecular weight ligands in aqueous solution  

Microsoft Academic Search

This work is aimed at reviewing the chemical literature dealing with thermodynamic aspects of the weak complex formation (species with logK values less than about 3) between alkali and alkaline earth metal ions with low molecular weight inorganic and organic ligands in aqueous solution. The following ligands (up to hexavalent anions) were examined in detail: (i) hydroxide, chloride, sulfate, carbonate

Pier G. Daniele; Claudia Foti; Antonio Gianguzza; Enrico Prenesti; Silvio Sammartano

2008-01-01

111

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

112

Liquid metal ion source and alloy  

DOEpatents

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

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

1988-10-04

113

Almost monoenergetic ions near the Earth's magnetosphere boundaries  

Microsoft Academic Search

More than 200 cases of energetic ion beams with an energy spectrum consisting of 1-3 narrow lines were observed during a period from August 1995 to August 1998 in the Earth's magnetosheath and in the region upstream of the Earth's bow shock. The observations are from the DOK-2 experiment on board of the Interball-1 spacecraft. Because the relative width at

Volt N. Lutsenko; Karel Kudela

1999-01-01

114

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

115

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

116

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

117

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

118

Ion beams and the ion/ion acoustic instability upstream from the earth's bow shock  

NASA Technical Reports Server (NTRS)

This paper considers the generation of enhanced ion acoustic fluctuations by field-aligned ion beams upstream from the earth's bow shock. Steep slopes in the beam distribution parallel and possibly strongly oblique to the magnetic field are correlated with bursts of ion acoustic noise in the upstream region. Linear theory shows that it is the slope of the beam distribution at oblique angles to the magnetic field that determines the growth rate of the ion/ion acoustic instability. Because of instrumentation limitations, it is suggested but not confirmed that enhanced ion acoustic fluctuations in the upstream region and in the presence of field-aligned beams are driven by such steep-sided distributions.

Fuselier, S. A.; Gary, Peter S.; Thomsen, M. F.; Bame, S. J.; Gurnett, D. A.

1987-01-01

119

Bouncing ion clusters in the earth's magnetosphere  

NASA Technical Reports Server (NTRS)

Mirroring clusters of ions have been observed by the UCSD auroral particles experiment on ATS 6. The dayside clusters are confined to the equatorial region, while the nightside events are low pitch angle and presumably associated with auroral processes. The bounce period of the clusters allows determination of the ion mass, and heavy ions have been observed.

Quinn, J. M.; Mcilwain, C. E.

1979-01-01

120

COMPUTATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS  

EPA Science Inventory

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

121

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

122

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

123

Heavy metal ions removal by chelating resin  

Microsoft Academic Search

Purpose – Preparation of chelating resin to be used in the removal of heavy metal ions from solutions. Design\\/methodology\\/approach – Chelating resin based on poly (glycidyl-methacrylate-co-N, N-methylene-bis-acrylamide) containing ethylenediamine was synthesised and used in removal of heavy metals from solutions. Findings – The optimal pH values for adsorption of different metal ions occur in the range 4.0-10.0 depending on the

N. M. Abd El-Moniem; M. R. El-Sourougy; D. A. F. Shaaban

2005-01-01

124

High compressibility of rare earth-based bulk metallic glasses  

NASA Astrophysics Data System (ADS)

The structural evolution of rare earth-based metallic glasses under high pressures at room temperature is investigated by X-ray diffraction synchrotron radiation. The high compressibility of rare earth-based bulk metallic glasses is found to be caused by transition from a low-density state to a high-density state under high pressures. This polyamorphic phase transition is achieved through the following: (1) smaller atoms are extruded into the clearance of the larger rare earth atoms; and (2) the volume of lanthanide elements collapses because of the delocalization of 4f electrons.

Zhao, W.; Wang, Y. Y.; Liu, R. P.; Li, G.

2013-01-01

125

Development of metallic ion beams using ECRIS  

NASA Astrophysics Data System (ADS)

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 the synthesis of the metal nanoparticles inside various host matrices. The special emphasis was put on the development of the nickel (Ni) and iron (Fe) ion beams using volatile compounds. The hydrocarbon cluster beams were also observed in the charge state distribution (CSD) of the ECR plasma produced by the dissociation of the vapors from the volatile compound of iron. Ni and Fe ion beams were utilized to make a dilute magnetic semiconductor phase (nickel in silicon and iron in silicon) by implantation method. The ion beams extracted from the metallic ECR plasma have been analyzed in energy and momentum using a high mass resolution dipole magnet. Studies of the CSD of the output metallic ion beams and the co-relations among various source parameters are presented.

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

2006-11-01

126

The discovery of nitrogen ions in the earth's magnetosphere  

NASA Technical Reports Server (NTRS)

Operating in a mass scanning mode, the Retarding Ion Mass Spectrometer (RIMS) has measured N(+) and N(++) ions in the magnetosphere. Both N(+) and N(++) are observed in the plasmasphere, with N(+) ions also seen flowing out of the northern polar cap at altitudes up to 3 earth radii. The N(+) fluxes are 5 to 10% of the O(+) fluxes with the N(++) fluxes at 1-5% of the N(+) fluxes.

Chappell, C. R.; Green, J. L.; Johnson, J. F. E.; Waite, J. H., Jr.; Olsen, R. C.

1982-01-01

127

Facilitated ion-transfer of alkaline-earth metal cations by naphtho-15-crown-5 across the water ? 1,2-dichloroethane interface: voltammetric and electrospray ionization mass spectrometric studies  

Microsoft Academic Search

The facilitated ion-transfer processes of Ca2+, Sr2+, and Ba2+ cations from an aqueous phase to a 1,2-dichloroethane (DCE) phase by naphtho-15-crown-5 (N15C5) were studied by cyclic voltammetry. When the metal ion concentrations in the aqueous phase were much higher than the N15C5 concentrations in the organic phase clear voltammograms were observed: the peak currents were controlled by the diffusion of

Hidekazu Doe; Norio Sakurada; Ryuichi Arakawa

2001-01-01

128

The influence of rare-earth ions on the low-temperature thermoluminescence of Bi4Ge3O12  

NASA Astrophysics Data System (ADS)

Low-temperature (20-290 K) thermoluminescence spectra of Bi4 Ge3 O12 reveal a range of trapping levels, some of which are common to both undoped and doped material. The emission spectra for undoped and transition-metal-doped Bi4 Ge3 O12 indicate that at low temperatures, intrinsic luminescence centres result in broad-band emission typical of signals from relaxed excitons or possibly excited bismuth ions. For material containing rare-earth ions, the signals are characteristic of the rare-earth dopants, even when the rare-earth ions are present in concentrations as low as 3 ppm. The temperatures of the glow peaks seen at ~54, 105 and 141 K for undoped material are strongly modified by the rare-earth ions. The trapping and recombination sites, monitored by rare-earth emission, are intimately linked, probably within large complex structures. For these three glow peaks the peak temperature varies smoothly with the ionic radii of the rare-earth impurities. These movements are substantial, with changes of up to 50 K, as a function of the rare-earth radii. Of all the rare-earth ions, europium forms the most stable recombination centres. This is probably because the trivalent europium ion is similar in size to the host (bismuth) ion for which it substitutes. Tentative models for trapping sites and thermoluminescence mechanisms are proposed.

Raymond, S. G.; Townsend, P. D.

2000-03-01

129

Nuclear Orientation Studies of Rare-Earth Metals.  

National Technical Information Service (NTIS)

The angular distributions of gamma rays from /sup 166m/Ho and exp 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 temperatu...

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

1980-01-01

130

Sorption of metal ions on alumina  

SciTech Connect

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

Baumgarten, E.; Kirchhausen-Duesing, U. [Heinrich-Heine Univ. Duesseldorf (Germany). Inst. fuer Physikalische Chemie und Elektrochemie] [Heinrich-Heine Univ. Duesseldorf (Germany). Inst. fuer Physikalische Chemie und Elektrochemie

1997-10-01

131

Inosine octamer stabilized by alkali earth metal cations - as studied by electrospray ionization mass spectrometry.  

PubMed

By using electrospray ionization mass spectrometry, inosine was found to be able to form an octamer stabilized by alkali earth metal cation, namely Ca(2+), Sr(2+) and Ba(2+), of which the most stable is that stabilized by Ca(2+) (ion [I8+Ca](2+)). It was established that 9-methylhypoxanthine (M) did not form an analogical octamer, since ion [M8+Ca](2+) was not detected. On the other hand, 9-methylhypoxanthine can form "mixed" octamers together with inosine (ions [InMm+Ca](2+), n + m = 8, were detected). PMID:24892295

Fra?ska, Magdalena

2014-01-01

132

Observations of molecular ions in the earth's magnetosphere  

NASA Technical Reports Server (NTRS)

The retarding ion mass spectrometer on Dynamics Explorer 1 operating over the polar cap during a large magnetic storm has measured fluxes of up to 10 to the 6th ions/sq cm s of the molecular ions N2(+), NO(+), and O2(+). These ions were measured beginning low in the satellite orbit (1.1 earth radii) and extending to about 3 earth radii geocentric altitude. Near perigee, the ions have a rammed distribution indicating a cold Maxwellian plasma (1000-2000 K). The molecular ions gradually shift to a field-aligned distribution at the higher alitudes. An upward flow of 5-10 km/s is found in these field-aligned measurements. The density of the molecular ions is on the order of 2/cu cm at all altitudes, and the energy of the ions generally increases as the satellite moves sunward across the southern polar cap. Kinetic energies of at least 20 eV were found at 2.5 earth-radii geocentric distance.

Craven, P. D.; Chappell, C. R.; Kakani, L.; Olsen, R. C.

1985-01-01

133

Immobilized calcein for metal ion preconcentration  

SciTech Connect

A technique is demonstrated for the preparation of immobilized calcein, (2',7',((bis(carboxymethyl)amino)methyl)-fluorescein), to be used for metal ion preconcentration. The calcein is of particular interest as a reagent for transition metals. The preconcentration is demonstrated for cobalt, copper, and nickel ions. Fluorescence spectra of the calcein at various pH values were obtained. Values were determined for the conditional binding constants of immobilized and dissolved calcein with the transition metal ions as a function of pH.

Not Available

1984-04-01

134

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

135

Reducing metal ion release following hip resurfacing arthroplasty.  

PubMed

Recent guidelines have suggested that routine postoperative care of patients with metal-on-metal hip prostheses should involve metal ion analysis. This study sought to investigate the relationship between bearing surface wear rates of metal components and serum metal ion analysis and also to quantify the incidence of excessive increases in serum metal ion concentrations post-hip resurfacing arthroplasty. PMID:21435493

Langton, David J; Joyce, Thomas J; Mangat, Navjeet; Lord, James; Van Orsouw, Maarten; De Smet, Koen; Nargol, Antoni V F

2011-04-01

136

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

137

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

PubMed

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 Eu(3+), Dy(3+), and Tb(3+) formed ML(2) complexes with stability constants of 10(8.26), 10(8.29), and 10(7.41) respectively. PMID:23295211

Wang, Li; Wang, Xiaoya; Wang, Yanmei

2013-03-15

138

Evaluation of alkali and alkaline earth metal cation selectivities of lariat ether amides by electrospray ionization mass spectrometry  

Microsoft Academic Search

Lariat ethers with pendant amide groups have shown promise as new ion sensors because of their selectivity towards particular\\u000a metal ions. In this study we report alkali and alkaline earth metal binding selectivities of dibenzo-16-crown-5 and fifteen\\u000a dibenzo-16-crown-5 lariat ether amides (LEAs) as determined by electrospray ionization mass spectrometry (ESI-MS). Additionally,\\u000a the influence of the acid\\/base nature of the solution

Sheldon M. Williams; Jennifer S. Brodbelt; Richard A. Bartsch

2003-01-01

139

Metal-ion recycle technology for metal electroplating waste waters  

SciTech Connect

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

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

1993-06-01

140

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

141

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

142

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

143

Heavy ion circulation in the earth's magnetosphere  

Microsoft Academic Search

We propose a mechanism whereby singly charged heavy ions from the plasmasphere are convected intermittently to the dayside magnetopause, accelerated there, swept into the distant tail lobes and boundary layer and convected earthward in the plasma sheet to re-enter the inner magnetosphere. The outer region of the plasmasphere is known to be stripped off during periods of enhancement of the

J. W. Freeman; H. K. Hills; T. W. Hill; P. H. Reiff; D. A. Hardy

1977-01-01

144

Uptake of metal ions on humic acids  

SciTech Connect

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

Pehlivan, E.; Arslan, G. [Selcuk University, Konya (Turkey)

2006-09-15

145

Serum metal ion levels after second-generation metal-on-metal total hip arthroplasty  

Microsoft Academic Search

Introduction  Metal-on-metal bearings for total hip arthroplasty are increasing in popularity. However, metal ion toxicity, metal hypersensitivity,\\u000a and metal carcinogenicity are the causes concern for patients with metal-on-metal hip replacement. We investigated serum levels\\u000a of cobalt and chromium ions in patients with successfully implanted second-generation metal-on-metal total hip arthroplasty\\u000a (THA) using PINNACLE-A (DePuy, Warsaw, IN, USA).\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Thirty-three patients underwent

Takao Imanishi; Masahiro Hasegawa; Akihiro Sudo

2010-01-01

146

Transparent monolithic metal ion containing nanophase aerogels  

Microsoft Academic Search

The formation of monolithic and transparent transition metal containing aerogels has been achieved through cooperative interactions of high molecular weight functionalized carbohydrates and silica precursors, which strongly influence the kinetics of gelation. After initial gelation, subsequent modification of the ligating character of the system, coordination of the group VIII metal ions, and supercritical extraction afford the aerogels. The structures at

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

1999-01-01

147

Ion Beam Studies of Hydrogen in Metals.  

National Technical Information Service (NTIS)

Methods based on ion implantation and nuclear reaction analysis were used to investigate the behavior of hydrogen isotopes in metals. The binding enthalpy of deuterium (D) at irradiation effects, He bubbles, D sub 2 bubbles, and metal-oxide interfaces was...

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

1984-01-01

148

Reactions of fulvic acid with metal ions  

Microsoft Academic Search

Fulvic acid is a water-soluble humic material that occurs widely in soils and waters and that tends to form water-soluble and water-insoluble complexes with a variety of metal ions, some of which are toxic. This paper presents information on the conditions under which the different types of FA-metal complexes are formed.

M. Schnitzer; H. Kerndorff

1981-01-01

149

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

150

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

Microsoft Academic Search

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

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

2009-01-01

151

A novel technique for doping silicate glasses with transition metals and rare-earth for waveguides applications  

Microsoft Academic Search

Field-Assisted Solid-State Ion-Exchange (FASSIE) technique for doping silicate glasses with either transition metals or rare earths has been attracting much attention for its potential application in light waveguides, luminescent materials and for the possibility to realize systems in which formation of metal nanoclusters is controlled by suitable post-exchange techniques. In this framework, metallic films of either silver or gold are

S. Ali; F. Gonella; E. Cattaruzza; A. Quaranta

2010-01-01

152

Upgraded vacuum arc ion source for metal ion implantation.  

PubMed

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. PMID:22380197

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

2012-02-01

153

Alloying behavior of the rare earth metals with manganese  

Microsoft Academic Search

General features of the phase equilibria for binary and ternary systems formed by rare earth metals (REM or R) with Mn and\\u000a other d-metals and p-elements (Me) are described and reviewed. On passing from the R?Mn alloys of the light REM to those of\\u000a the heavy ones, a progressive change in the shape of the phase diagrams and an increasing

R. Ferro; A. Saccone; S. Delfino; D. Macciò; M. Giovannini

1997-01-01

154

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

155

Mutagenicity of metal ions in bacteria.  

PubMed

The mutagenicity of 24 metal salts was investigated in plate incorporation and fluctuation assays with Salmonella TA strains or Escherichia coli WP2 uvrA pKm 101. Chromate(VI) and selenate(VI) ions were found to be mutagenic in plate incorporation assays employing conventional media. On the other hand, cadmium(II), beryllium(II), chromate(VI), and metavanadate(V) ions were detected in conventional fluctuation assays, indicating the importance of this technique in detection of metal mutagens. Modified culture media, with trimetaphosphate ions in place of orthophosphate as the sole phosphate source for bacterial growth, were also used in this study. The media modifications prevented precipitation of metals such as nickel and cadmium as their insoluble phosphates, and allowed detection of the mutagenicity of metavanadate ions in plate incorporation assays. However, the fluctuation technique using standard media was shown to detect a wider range of mutagenic metal ions than tests with modified media. It is notable that metaarsenite(III), arsenate(V), and nickel(II) ions were not found to be mutagenic in any of the assays although they are known to be carcinogenic and are mutagenic in other test systems. Their lack of mutagenicity in the modified media indicates that precipitation of these ions as orthophosphates is not the reason for their lack of activity in standard bacterial assays. PMID:3884331

Arlauskas, A; Baker, R S; Bonin, A M; Tandon, R K; Crisp, P T; Ellis, J

1985-04-01

156

Mutagenicity of metal ions in bacteria  

SciTech Connect

The mutagenicity of 24 metal salts was investigated in plate incorporation and fluctuation assays with Salmonella TA strains or Escherichia coli WP2 uvrA pKm 101. Chromate(VI) and selenate(VI) ions were found to be mutagenic in plate incorporation assays employing conventional media. On the other hand, cadmium(II), beryllium(II), chromate(VI), and metavanadate(V) ions were detected in conventional fluctuation assays, indicating the importance of this technique in detection of metal mutagens. Modified culture media, with trimetaphosphate ions in place of orthophosphate as the sole phosphate source for bacterial growth, were also used in this study. The media modifications prevented precipitation of metals such as nickel and cadmium as their insoluble phosphates, and allowed detection of the mutagenicity of metavanadate ions in plate incorporation assays. However, the fluctuation technique using standard media was shown to detect a wider range of mutagenic metal ions than tests with modified media. It is notable that metaarsenite(III), arsenate(V), and nickel(II) ions were not found to be mutagenic in any of the assays although they are known to be carcinogenic and are mutagenic in other test systems. Their lack of mutagenicity in the modified media indicates that precipitation of these ions as orthophosphates is not the reason for their lack of activity in standard bacterial assays.

Arlauskas, A.; Baker, R.S.U.; Bonin, A.M.; Tandon, R.K.; Crisp, P.T.; Ellis, J.

1985-04-01

157

Tyrosine Modification Enhances Metal Ion Binding  

PubMed Central

Tyrosine sulphation is a common modification of many proteins, and the ability to phosphorylate tyrosine residues is an intrinsic property of many growth factor receptors. We have utilized the peptide hormone cholecystokinin (CCK8), which occurs naturally in both sulphated and unsulphated forms, as a model to investigate the effect of tyrosine modification on metal ion binding. The changes in absorbance and fluorescence emission on Fe3+ ion binding indicated that tyrosine sulphation or phosphorylation increased the stoichiometry from 1 to 2, without greatly affecting the affinity (0.6–2.8 ?M at pH 6.5). Measurement of calcium binding with a calcium-selective electrode revealed that phosphorylated CCK8 bound two Ca2+ ions. CCK8 and sulphated CCK8 each bound only one Ca2+ ion with lower affinity. Binding of Ca2+, Zn2+ or Bi3+ ions to phosphorylated CCK8 did not cause any change in absorbance, but substantially increased the change in absorbance on subsequent addition of Fe3+ ions. Our results demonstrate that tyrosine modification may increase the affinity of metal ion binding to peptides, and imply that metal ions may directly regulate many signaling pathways.

BALDWIN, Graham S.; BAILEY, Michael F.; SHEHAN, B. Philip; SIMS, Ioulia; NORTON, Raymond S.

2008-01-01

158

Metal Ion Hypersensitivity in Metal-on-Metal Hip Arthroplasty  

Microsoft Academic Search

Total hip arthroplasty with use of metal-on-metal bearings has been reintroduced as an alternative to metal-on-polyethylene\\u000a bearings because of theoretical advantages such as reduced wear and a lower prevalence of osteolysis. However, we have observed\\u000a early osteolysis in nine patients (ten hips) out of 165 patients (169 hips) who had been managed with total hip replacements\\u000a using a contemporary metal-on-metal

Y.-S. Park; Y.-W. Moon; S.-J. Lim

159

Structure determination of gaseous metal and semi-metal cluster ions by ion mobility spectrometry  

Microsoft Academic Search

Gas phase ion mobility spectrometry in combination with quantum chemical calculations has proven to be extremely useful for the structure determination of cluster ions. After a short introduction into the methodology, investigations focused on clusters of different main group metals and semi-metals are reviewed. Based on the findings of different groups, it became apparent that in many cases small clusters

Patrick Weis

2005-01-01

160

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

SciTech Connect

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

Bartsch, Richard A.

2012-06-04

161

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

162

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

163

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

164

Binding of tetrahedral halocomplexes of polyvalent metal ions in an ionic model  

Microsoft Academic Search

Summary  Long-lived tetrahedral coordination of polyvalent metal ions by halogen ions is known to be stable in a number of liquid halide\\u000a mixtures. We evaluate the binding of isolated tetrahedral halocomplexes for the alkaline earth metals and for Al, with the\\u000a main aim of assessing their stability and their bond length. An appropriate interionic force model is available for the halides

Wang Li; M. P. Tosi

1988-01-01

165

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

166

Interaction between excitons and rare-earth ions  

NASA Astrophysics Data System (ADS)

Energy transfer between rare-earth (RE) ions and excitons in semiconductors has already been known for some time. In this paper we would like to direct your attention to the interaction between excitons and RE ions in ionic crystals as used, e.g. for laser applications. A suitable model substance to study these effects is RE-doped CsCdBr 3. The reasons are: (i) the low phonon frequencies due to the heavy ion masses ( ??max<200 cm -1); (ii) metastable excitonic states in the visible spectral range; (iii) strong exciton-ion interaction due to covalent overlap of the wavefunctions. Due to the low phonon frequencies, multiphonon processes of the RE ions are reduced drastically and ion-exciton processes can be studied in more detail. The following processes were found: (i) exciton-mediated nonradiative relaxations. These processes can bridge much larger energy gaps than direct multiphonon relaxation and are more efficient. The reason is that the nonradiative multiphonon relaxation of the RE ion is dominated by a fast multistep one-phonon relaxation of the exciton by energy transfer; (ii) exciton-mediated quantum upconversion. This effect is based on a cooperative energy transfer from two excited RE ions to an exciton and a subsequent back transfer to a single ion. This process is much faster than upconversion by phonon-assisted cross relaxation between two excited RE ions; (iii) exciton-induced changes in the crystal-field splitting of RE ions. Energy levels of RE ions in resonance with the excitons show crystal-field splittings which cannot be described by the parameters suitable for the other levels. We propose an increased covalent overlap between the wavefunction of the RE ion and of the exciton-forming ligands due to hybridization as an explanation for this effect.

Heber, J.; Neukum, J.; Altwein, M.; Demirbilek, R.; Bodenschatz, N.

1998-09-01

167

Transmission and absorption spectra of aluminophosphate-doped glasses with rare-earth ions  

Microsoft Academic Search

Aluminophosphate glasses doped with rare-earth ions have recently attracted a large interest owing to their relevant non-linear optical properties. Until now, all studies were done over the glasses doped with rare-earth ions in which the rare-earth ions were into a vitreous silica matrix. Our study was made as for rare-earth ions into a vitreous aluminophosphate matrix. In the first step,

Rodica Rogojan; Paul E. Sterian; Mihai Elisa

1998-01-01

168

Influence of metal ion complexation on the metastable fragmentation of DNA hexamers  

NASA Astrophysics Data System (ADS)

Here, we study the metastable decay of 5'-d(TTGCTT) in the presence of 0-6 alkaline metal ions (Li+, Na+, K+, Rb+) and 0-3 alkaline earth metal ions (Mg2+ and Ca2 +), which replace the corresponding number of protons in the oligonucleotide. We find that all ions studied here stabilize the oligonucleotide with respect to simple 3'-C-O backbone cleavage, but at the same time these metal ions promote a central oligonucleotide deletion accompanied by a concomitant recombination of the terminal d(TT) groups. We find that the quenching of the 3'-C-O backbone cleavage is not ion specific, since it is due to the removal of the phosphate protons upon replacement with the respective metal ions. The central nucleotide deletion competes with the 3'-C-O backbone cleavage channels and is thus promoted through the replacement of the exchangeable protons against metal ions. However, with increasing positive charge density of the metal ions the yield of the central nucleotide deletion further increases. We attribute this effect to the necessity of sufficient proximity of the terminal d(TT) group to allow for their recombination on this reaction path. Hence, the formation of a reactive conformer is mediated by the metal ions. Contribution to the Topical Issue "Nano-scale Insights into Ion-beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Paulo Limão-Vieira and Malgorzata Smialek-Telega.

Piekarczyk, Andreas; Bald, Ilko; Flosadóttir, Helga D.; Ómarsson, Benedikt; Lafosse, Anne; Ingólfsson, Oddur

2014-06-01

169

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

170

Nitrenium ions as ligands for transition metals  

NASA Astrophysics Data System (ADS)

Unlike N-heterocyclic carbenes (NHCs), which are now used ubiquitously in metal-based chemistry, the nitrogen-derived analogue (in which a carbon is replaced with the isoelectronic nitrogen cation, a nitrenium ion) has remained elusive as a ligand for metals. This is especially intriguing, because several other main-group analogues of NHCs have been prepared, and have been shown to coordinate with transition-metal complexes. Here, we describe the preparation of several N-heterocyclic nitrenium ions that are isoelectronic and isostructural to NHCs, and study their ligand properties. The formation of relatively strong nitrenium-metal bonds is unambiguously confirmed, in solution by selective 15N-labelling experiments, and in the solid state by X-ray crystallography. Experimental and computational studies of the electronic properties of this novel type of ligand suggest that they are poor ?-donors and good ?-acceptors.

Tulchinsky, Yuri; Iron, Mark A.; Botoshansky, Mark; Gandelman, Mark

2011-07-01

171

A potentiometeric study of protonation and complex formation of xylenol orange with alkaline earth and aluminum ions  

Microsoft Academic Search

Xylenol orange (XO) is one of the complexometric indicators, that can bind to metal cations at both their amino and acidic groups. In this study the protonation constants and distribution diagrams of XO were studied pH-metrically, and the corresponding six protonation constants were calculated. The complex formation between XO (L) and alkaline earth ions (M) was investigated and the formation

M. B Gholivand; F Bamdad; J Ghasemi

1998-01-01

172

Mutagenicity of metal ions in bacteria  

Microsoft Academic Search

The mutagenicity of 24 metal salts was investigated in plate incorporation and fluctuation assays with Salmonella TA strains or Escherichia coli WP2 uvrA pKm 101. Chromate(VI) and selenate(VI) ions were found to be mutagenic in plate incorporation assays employing conventional media. On the other hand, cadmium(II), beryllium(II), chromate(VI), and metavanadate(V) ions were detected in conventional fluctuation assays, indicating the importance

A. Arlauskas; R. S. U. Baker; A. M. Bonin; R. K. Tandon; P. T. Crisp; J. Ellis

1985-01-01

173

[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

174

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

175

Ion probe measurement of rare earth elements in biogenic phosphates  

NASA Astrophysics Data System (ADS)

The rare earth element (REE) distributions in individual fish teeth and conodonts have been measured by ion probe. Concentrations and La/Yb ratios show little variations, except in the enamel, which suggests that REE uptake from the sedimented biogenic debris takes place at the water-sediment interface as an essentially quantitative process without fractionation. Late diagenetic disturbances remained of marginal importance. Hence, REE in phosphatic debris might reflect the input from the overlying water column.

Grandjean, Patricia; Albarède, Francis

1989-12-01

176

Spectroscopy and laser performance of some rare earth and transition-metal-doped garnets  

NASA Astrophysics Data System (ADS)

Investigation of the spectroscopic properties and laser performance of rare earth and transition metal ions doped crystals (garnets) is presented. Recent spectroscopic results of energy transfer and back transfer mechanism in Cr:Tm:Ho:YAG, Cr:Tm:Ho:LuAG (Lu3Al5O12) at a variety of temperatures (10K-300K) will be reported. A direct energy transfer from Tm3+ excited states to Ho3+ 5I7 lasing level was observed and analyzed. Multipolar interaction between special sites of Cr3+ and rare earth lasing ions (Tm3+, Ho3+), which results from a strong correlation placement distribution was found and analyzed. The effect of this interaction on the enhancement of laser efficiency will be discussed. The room temperature performance and the laser parameters of broadly tunable solid state lasers (at 1150-1600 nm), based on Cr4+ doped different garnets will be presented and discussed as well.

Kalisky, Yehoshua Y.; Zhang, Jiamin; Rotman, Stanley R.; Kokta, Milan R.

1995-04-01

177

Persistent luminescence phenomena in materials doped with rare earth ions  

NASA Astrophysics Data System (ADS)

The luminescent efficiency of rare earth ions is usually drastically lowered when defects are present in the host lattice. Persistent luminescence is the most recent rare earth application based on lattice defects. Typical materials are the Eu 2+-doped alkaline earth aluminates, MAl 2O 4:Eu 2+ ( M=Ca and Sr). The trivalent R 3+ ions as co-dopants enhance greatly the duration and intensity of persistent luminescence. As a result of very slow thermal bleaching of the excitation energy from the lattice defects acting as traps, the new persistent luminescent materials yield luminescence still visible to naked eye for more than 10 h. Despite the seemingly simple stoichiometry and structure of these materials, the determination of persistent luminescence mechanism(s) presents a very complicated problem. This report presents in detail some of the factors affecting the luminescence properties of the Eu 2+-, R 3+-doped MAl 2O 4. The possible mechanisms involved with different defect centers and interactions between them and the emitting Eu 2+ ion are discussed based on the results of systematic investigations carried out on the preparation, composition, structure and different luminescence properties.

Aitasalo, T.; Dere?, P.; Hölsä, J.; Jungner, H.; Krupa, J.-C.; Lastusaari, M.; Legendziewicz, J.; Niittykoski, J.; Str?k, W.

2003-02-01

178

[The application of alkaline-earth metal sulphide material in radiation dose measurement].  

PubMed

In the present paper, the material of alkaline-earth metal sulphide doped with two kinds of rare-earth metal ions was prepared by carbon reduction method, and the radiation characteristics of optically stimulated luminescence of this material are described. The PMMA dosimeter films were taken intothe radiation source,then the fluorescence signal from the dosimeter films was measured with the test system build by ourselves. The relation between the radiation dose and the fluorescence intensity of the dosimeter films was obtained. The measuring range of the dosimeter was from 0.01 to 1,000 Gy (5 orders of magnitude), and there is a good linear relationship between stimulated luminescence signal value of the material and the dose. It demonstrates that this device has a good prospect. This equipment is relatively simple, small in size and low in power consumption. This device is suitable for measuring the space radiation dose exploration. PMID:19626867

Chen, Chao-Yang; Fan, Yan-Wei; Liu, Yan-Ping; Wang, Jun-Hua; Ba, Wei-Zhen; Guo, Qi; Chang, Ai-Min; Lu, Wu

2009-04-01

179

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

180

Genetically Engineered Pores Sensing Metal Ions.  

National Technical Information Service (NTIS)

Stochastic sensing with pore-forming proteins has been established as a means for sensing metal ions by using engineered forms of alpha-hemolysin as the sensor elements. The alpha-hemolysin pore is a heptamer, which has disadvantages for certain manipulat...

H. Bayley S. Conlan

2000-01-01

181

Dynamical Correlation In Some Liquid Alkaline Earth Metals Near Melting  

NASA Astrophysics Data System (ADS)

The study of dynamical variables: velocity autocorrelation function (VACF) and power spectrum of liquid alkaline earth metals (Ca, Sr, and Ba) have been presented based on the static harmonic well approximation. The effective interatomic potential for liquid metals is computed using our well recognized model potential with the exchange correlation functions due to Hartree, Taylor, Ichimaru and Utsumi, Farid et al. and Sarkar et al. It is observed that the VACF computed using Sarkar et al. gives the good agreement with available molecular dynamics simulation (MD) results [Phys Rev. B 62, 14818 (2000)]. The shoulder of the power spectrum depends upon the type of local field correlation function used.

Thakore, B. Y.; Suthar, P. H.; Khambholja, S. G.; Gajjar, P. N.; Jani, A. R.

2010-12-01

182

Tyrosine modification enhances metal-ion binding.  

PubMed

Tyrosine sulfation is a common modification of many proteins, and the ability to phosphorylate tyrosine residues is an intrinsic property of many growth-factor receptors. In the present study, we have utilized the peptide hormone CCK(8) (cholecystokinin), which occurs naturally in both sulfated and unsulfated forms, as a model to investigate the effect of tyrosine modification on metal-ion binding. The changes in absorbance and fluorescence emission on Fe(3+) binding indicated that tyrosine sulfation or phosphorylation increased the stoichiometry from 1 to 2, without greatly affecting the affinity (0.6-2.8 microM at pH 6.5). Measurement of Ca(2+) binding with a Ca(2+)-selective electrode revealed that phosphorylated CCK(8) bound two Ca(2+) ions. CCK(8) and sulfated CCK(8) each bound only one Ca(2+) ion with lower affinity. Binding of Ca(2+), Zn(2+) or Bi(3+) to phosphorylated CCK(8) did not cause any change in absorbance, but substantially increased the change in absorbance on subsequent addition of Fe(3+). The results of the present study demonstrate that tyrosine modification may increase the affinity of metal-ion binding to peptides, and imply that metal ions may directly regulate many signalling pathways. PMID:18636967

Baldwin, Graham S; Bailey, Michael F; Shehan, B Philip; Sims, Ioulia; Norton, Raymond S

2008-11-15

183

Pentadienyl chemistry of the heavy alkaline-earth metals revisited.  

PubMed

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

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

2014-05-14

184

Liquid structure of the alkaline-earth metals  

Microsoft Academic Search

We present ab initio calculations of the liquid structure of the alkaline-earth metals. Our approach is based on the neutral-pseudoatom method to obtain the interionic pair potential and on the variational-modified-hypernetted-chain integral-equation theory of liquids [Y. Rosenfeld, J. Stat. Phys. 42, 437 (1986)] to obtain the liquid structure. This combination results in a whole theory that is free of adjustable

L. E. González; A. Meyer; M. P. Iñiguez; D. J. González; M. Silbert

1993-01-01

185

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

186

Synthesis and stabilization-advances in organoalkaline earth metal chemistry.  

PubMed

The last decade has seen an impressive growth in alkaline earth metal chemistry, with applications ranging from synthetic organic and polymer chemistry to materials science. As a consequence, alkaline earth metal chemistry has made a leap from obscurity into the spotlight of modern organometallic chemistry. Much of this rapid development was made possible by the establishment of novel synthetic procedures that allowed facile access to the target compounds, as many conventional synthetic routes posed and continue to pose significant limitations. Novel approaches have allowed the preparation of a multitude of compounds, initiating progress not thought possible just five years ago. Examination of the new compounds delineates several factors responsible for their structure and function. Key elements in the coordination, aggregation behavior, and reactivity of these systems have been linked to secondary interactions, including M-Cpi, M-Npi, M-F, and M-H(agostic) interactions. This feature article will provide a very brief overview of established synthetic procedures, including a brief discussion on specific shortcomings. This will be followed by a detailed presentation of novel methodologies that are the core of the rapid development of alkaline earth metal chemistry. The second part of the article will be concerned with the analysis of various secondary interactions and their role in the further development of this rapidly emerging field of chemistry. PMID:20445937

Buchanan, William D; Allis, Damian G; Ruhlandt-Senge, Karin

2010-07-01

187

Metal ions affecting reproduction and development.  

PubMed

Many metal ions (lead, mercury, arsenic, cadmium, chromium, nickel, vanadium, copper, lithium) exert a wide variety of adverse effects on reproduction and development, including influence on male and female subfertility or fertility, abortions, malformations, birth defects, and effects on the central nervous system. The effects produced by metal ions depend on several factors, such as timing and duration of exposure, their distribution and accumulation in various organs (e.g., the nervous system), and on the interference with specific developmental processes. Neonatal and early postnatal periods are lifespan segments during which sensitivity to metals is high; e.g., lead toxicity on the developing organism is paradigmatic of related well known and still open questions. In more recent decades, important mechanisms of action have been suggested: the endocrine disruption via impact of metal ions on reproductive hormones and the oxidative stress. While experimental data provide clear evidence of effects of many metals, human data are scant and traditionally limited to high levels of a few metal ions, like lead on male fertility. Less documented are reproductive effects for mercury, manganese, chromium, nickel, and arsenic for the same gender. More complex is the demonstration of effects on female reproduction and on pregnancy. The action of lead, arsenic, cadmium, chromium, and mercury may in fact be relevant in several stages, beginning in fetal life, during early development or maturity, and is characterized by subfertility, infertility, intrauterine growth retardation, spontaneous abortions, malformations, birth defects, postnatal death, learning and behavior deficits, and premature aging. Also, for females the evidences of specific aspects such as fertility or abortions are usually higher and clearer from animal experiments than from human studies. PMID:21473384

Apostoli, Pietro; Catalani, Simona

2011-01-01

188

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

189

Biosensors for the Detection of Heavy Metal Ions.  

National Technical Information Service (NTIS)

Phytochelatins, metallothioneins and glutathione are under investigation as biological components for the development of biosensors for heavy metal ion detection in aqueous solutions. These peptides/proteins selectively bind heavy metal ions by thiolate c...

R. Hilpert F. Binder M. H. Zenk

1989-01-01

190

Alkali metal ion-selective electrodes based on relevant alkali metal ion doped manganese oxides  

Microsoft Academic Search

Potentiometric properties of manganese oxides doped with alkali metal ions (Na+, K+, Rb+ and Cs+), which were prepared by heating mixed solutions (starting solution) of each alkali metal and Mn2+ ions, were examined. Electrodes based on mixed phases of Nao44MnO2\\/Mn2O3 and hollandite KMn8O16\\/M2O3 found by X-ray powder diffraction (XRD) exhibited Na+- and K+-selective responses with a near-Nernstian slope, respectively, when

Yukinori Tani; Yoshio Umezawa

1998-01-01

191

IUPAC-NIST Solubility Data Series. 79. Alkali and Alkaline Earth Metal Pseudohalides  

Microsoft Academic Search

This volume presents solubility data of azides, cyanides, cyanates, and thiocyanates of alkali metals, alkaline earth metals, and ammonium. Covered are binary and ternary systems in all solvents. No solubility data have been found for some of the compounds of alkali metals, alkaline metals, and ammonium. These include beryllium and magnesium azides, lithium, rubidium cesium, ammonium, and alkaline earth cyanates

Jiri Ha´la

2004-01-01

192

High-current pulsed ion source for metallic ions  

SciTech Connect

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

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

1981-03-01

193

Coprecipitation of alkali metal ions with calcium carbonate  

Microsoft Academic Search

The coprecipitation of alkali metal ions (Li + , Na + , K + and Rb + ) with calcium carbonate has been studied experimentally and the following results have been obtained: 1. (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. 2. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite

Minoru Okumura; Yasushi Kitano

1986-01-01

194

Ligand Field Stabilization Control of Metal Ion Binding.  

National Technical Information Service (NTIS)

Specific metal ions bind to particular sites within proteins. The factors that might influence the thermodynamics of metal ion binding to proteins include metal ion radius, hard-soft acid-base effects, and ligand field stabilization energy changes. We hav...

J. M. Berg

1994-01-01

195

Fulvic acid: modifier of metal-ion chemistry  

Microsoft Academic Search

Fulvic acid, which is derived from the decay of plants and animals, is being studied for its role in the transport and toxicity of metal ions in soil and water. It is discussed in relation to the origin of humic substances and its interactions with metal ions. Techniques for investigating complexes of fulvic acid and metal ions are presented. They

Robert A. Saar; James H. Weber

1982-01-01

196

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

197

Engineering of microorganisms towards recovery of rare metal ions.  

PubMed

The bioadsorption of metal ions using microorganisms is an attractive technology for the recovery of rare metal ions as well as removal of toxic heavy metal ions from aqueous solution. In initial attempts, microorganisms with the ability to accumulate metal ions were isolated from nature and intracellular accumulation was enhanced by the overproduction of metal-binding proteins in the cytoplasm. As an alternative, the cell surface design of microorganisms by cell surface engineering is an emerging strategy for bioadsorption and recovery of metal ions. Cell surface engineering was firstly applied to the construction of a bioadsorbent to adsorb heavy metal ions for bioremediation. Cell surface adsorption of metal ions is rapid and reversible. Therefore, adsorbed metal ions can be easily recovered without cell breakage, and the bioadsorbent can be reused or regenerated. These advantages are suitable for the recovery of rare metal ions. Actually, the cell surface display of a molybdate-binding protein on yeast led to the enhanced adsorption of molybdate, one of the rare metal ions. An additional advantage is that the cell surface display system allows high-throughput screening of protein/peptide libraries owing to the direct evaluation of the displayed protein/peptide without purification and concentration. Therefore, the creation of novel metal-binding protein/peptide and engineering of microorganisms towards the recovery of rare metal ions could be simultaneously achieved. PMID:20393699

Kuroda, Kouichi; Ueda, Mitsuyoshi

2010-06-01

198

Heat partitioning in metal-silicate plumes during Earth differentiation  

NASA Astrophysics Data System (ADS)

We present an analytical model for core formation that includes both metal diapirs and liquid conduits and produces a superheated core. We start from the standard model of Earth formation consisting of accretion by planetesimal or planetary embryo impacts large enough to create global or local magma oceans. Our model consists of two main fluid dynamical structures: 1) large liquid metal diapirs and 2) narrow conduits with liquid silicate and small liquid metal droplets. We assume that transport of metal from a near-surface magma ocean to the growing core occurs within these structures. The release of gravitational potential energy from the descent of the metal is converted to heat through viscous dissipation, which is broadly distributed around the large liquid metal diapirs but localized in the conduit around the smaller metal droplets. This model gives an average core temperature during accretion and a post-accretion average core temperature for a broad range of impact histories and chemical quilibration assumptions. We consider three types of Earth accretion histories with impacts that are evenly spaced over 30 Ma. These include: 1) equal-sized impacts, 2) equal-sized impacts with a final Mars-sized impact, and 3) exponentially decreasing impact sizes with a final Mars-sized impact. Our preferred model is based on core-mantle chemical equilibrium estimates that correspond to a fractionation, f, the ratio of metal in the diapir to the total metal content in each impact of f = 0.64 and accretion history type 3. This model produces a post-accretion average core temperature that ranges from 5930 K to 5700 K for 8 to 90 impacts, respectively. The efficiency of the metal-silicate conduits, defined as the ratio of the heating of the core by the conduits to their potential energy released has an approximate value of 0.59 for our preferred model. The residual post-accretion structures include a basal magma ocean and a network of mantle conduits that may dictate the style of Hadean tectonics.

King, Christina; Olson, Peter

2011-04-01

199

Metal-Insulator Transition and Giant Negative Magnetoresistance in Amorphous Magnetic Rare Earth Silicon Alloys  

SciTech Connect

Large negative magnetoresistance and anomalous magnetic properties are found in amorphous Si doped with magnetic rare earth ions near the metal-insulator transition. The resistivity below 50K rises orders of magnitude above that of comparable composition nonmagnetic alloys and is strongly reduced by a magnetic field. Magnetization measurements show noninteracting moments at high temperature which develop antiferromagnetic interactions below 50K.We suggest that these results are due to formation below 50K of a dense concentration of magnetic polarons which localize conduction electrons. {copyright} {ital 1996 The American Physical Society.}

Hellman, F.; Tran, M.; Gebala, A.; Wilcox, E.; Dynes, R. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)

1996-11-01

200

Metal hydrides for lithium-ion batteries  

Microsoft Academic Search

Classical electrodes for Li-ion technology operate via an insertion\\/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH2 with Li that constitutes the first use of a metal-hydride

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

2008-01-01

201

Alkaline and alkaline earth metal phosphate halides and phosphors  

DOEpatents

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

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

2012-11-13

202

Magnetic Properties of 4D-TRANSITION Metal and Rare Earth Metal Clusters  

Microsoft Academic Search

In this dissertation, we present results of experiments designed to explore the magnetic properties of clusters, specifically focusing on 4d-transition metal and rare earth metal clusters. We report a non-zero magnetic moment of rhodium 8 to 60-atom clusters. These superparamagnetic rhodium clusters provide the first observation of magnetism in clusters composed of a material which is non-ferromagnetic in the bulk.

Anne Junkin Cox

1994-01-01

203

Metal hydrides for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH2 with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH2 electrode shows a large, reversible capacity of 1,480mAhg-1 at an average voltage of 0.5V versus Li+/Li? which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH2. Furthermore, the reaction is not specific to MgH2, as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH2, which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries.

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

2008-11-01

204

Patterned Polymer-Metal Ion Complexes  

NASA Astrophysics Data System (ADS)

The doping of polymers with metal ions has been of interest due to the possibility of tailoring their electrical, optical and mechanical properties. Such tailored polymers have potential applications in a variety of areas including flexible electronic devices and systems, optical systems such as those for holography, data storage, and mechanical systems. To extend the applications of metal doped polymers to novel micro-devices and systems, it is pertinent to develop methodologies to pattern or structure such polymers in small dimensions, often in the micro-scale. We report on the development of micro-patterned thin films of polyvinyl alcohol (PVA) doped with copper (Cu^2+) ions. The films were patterned in the micro-scale dimensions and larger by contact printing onto a substrate. Patterned Cu^2+ doped PVA films were also made by combining solution casting with micro-molding. Raman spectroscopic analysis of the developed Cu^2+ doped PVA films revealed the presence of PVA-Cu^2+ complexes. Further characterization of the Cu^2+ doped PVA films for electrical conductivity and x-ray diffraction is in progress and will be presented. The doping of PVA by other metal ions is also being explored and initial results will be presented.

Hoffpauir, Jonathan; Korivi, Naga; Ajmera, Pratul

2010-10-01

205

On the Metal Ion Selectivity of Oxoacid Extractants  

SciTech Connect

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

Hay, Benjamin [ORNL; Chagnes, Alexandre [Chimie ParisTech; Cote, Gerard [Chimie ParisTech

2013-01-01

206

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

207

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

PubMed

Changes in protein ion conformation as a result of nonspecific adduction of metal ions to the protein during electrospray ionization (ESI) from aqueous solutions were investigated using traveling wave ion mobility spectrometry (TWIMS). For all proteins examined, protein cations (and in most cases anions) with nonspecific metal ion adducts are more compact than the fully protonated (or deprotonated) ions with the same charge state. Compaction of protein cations upon nonspecific metal ion binding is most significant for intermediate charge state ions, and there is a greater reduction in collisional cross section with increasing number of metal ion adducts and increasing ion valency, consistent with an electrostatic interaction between the ions and the protein. Protein cations with the greatest number of adducted metal ions are no more compact than the lowest protonated ions formed from aqueous solutions. These results show that smaller collisional cross sections for metal-attached protein ions are not a good indicator of a specific metal-protein interaction in solution because nonspecific metal ion adduction also results in smaller gaseous protein cation cross sections. In contrast, the collisional cross section of ?-lactalbumin, which specifically binds one Ca(2+), is larger for the holo-form compared with the apo-form, in agreement with solution-phase measurements. Because compaction of protein cations occurs when metal ion adduction is nonspecific, elongation of a protein cation may be a more reliable indicator that a specific metal ion-protein interaction occurs in solution. PMID:23733259

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

2013-11-01

208

Effect of rare earth metal oxide additions to tungsten electrodes  

Microsoft Academic Search

A comparative study has been made on the operating characteristics of gas-tungsten arc (GTA) welding for several types of\\u000a electrodes. The work was carried out with a pure tungsten electrode and tungsten electrodes activated with a small quantity\\u000a of the rare earth metal oxides, La2O3, Y2O3, CeO2, and with ZrO2, ThO2, and MgO. Their behaviors during arcing were analyzed and

Alber A. Sadek; Masao Ushio; Fukuhisa Matsuda

1990-01-01

209

Magnetism of perovskite cobaltites with Kramers rare-earth ions  

NASA Astrophysics Data System (ADS)

The band-gap insulators RECoO3 (RE = Nd3+, Sm3+, and Dy3+) with Co3+ ions stabilized in the non-magnetic low-spin state have been investigated by specific heat measurements. The experiments evidence an antiferromagnetic ordering of the rare earths with Néel temperature of TN = 1.25, 1.50, and 3.60 K for NdCoO3, SmCoO3, and DyCoO3, respectively. With increasing external field, the lambda peak in specific heat, indicative of the transition, shifts to lower temperatures and vanishes for field of about 3 T. Starting from this point, a broader Schottky peak is formed, centered in 1 K range, and its position is moved to higher temperatures proportionally to applied field. The origin of the peak is in Zeeman splitting of the ground Kramers doublet, and the gradual shift with field defines effective g-factors for the rare-earth pseudospins in studied compounds. The results obtained are confronted with the calculations of crystal field splitting of the rare-earth multiplets.

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

2014-05-01

210

Ion-beam sputtering and nanostructures of noble metals  

Microsoft Academic Search

Using the technique of ion-beam sputtering on gold (Au) and silver (Ag) metal films, metal nanoclusters vis-à-vis nanostructure materials are synthesized on silica glass substrates. Analyses of Rutherford backscattering spectra of Ar+-ion irradiated films confirm the ion-beam sputtering of metal films. Exponential decrease of experimentally measured areal density of Au atoms with the increase of ion doses has been elucidated.

P. Gangopadhyay; Sachin Kumar Srivastava; P. Magudapathy; T. N. Sairam; K. G. M. Nair; B. K. Panigrahi

2010-01-01

211

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

SciTech Connect

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

Thorn, A.; Ritter, E.; Zschornack, G. [Fachrichtung Physik, Technische Universitaet Dresden, Helmholtzstrasse 10, D-01069 Dresden (Germany); Ullmann, F. [DREEBIT GmbH, Zur Wetterwarte 50, D-01109 Dresden (Germany); Pilz, W.; Bischoff, L. [Helmholtzzentrum Dresden-Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany)

2012-02-15

212

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

PubMed

We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au(60 +). The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented. PMID:22380207

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

2012-02-01

213

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

DOEpatents

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

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

1992-01-01

214

Theory of Zeeman effect for rare earth ions in crystal field with D2 symmetry and application to rare earth garnets  

Microsoft Academic Search

Rare earth ions in solids frequently exhibit sharp-line optical spectra. In this paper a part of the theory of the Zeeman effect for the lines is developed, first for a single rare earth ion in D2 symmetry, and secondly for rare earth ions at different inequivalent sites in garnet crystals. The results for the case in which the crystal field

T. Kambara; W. J. Haas; F. H. Spedding; R. H. Good Jr

1973-01-01

215

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

PubMed

Increased wear leads to elevated systemic and local metal ion concentrations for patients treated with metal-on-metal bearings. The local metal ion content in the close environment of the joint replacement (e.g. joint aspirate or tissue) is several times higher compared to the systemic metal content (e.g. in blood or serum). As a result of increased metal ion levels, local and systemic effects, such as osteolysis, pseudotumors, sensitization or in rare cases toxicity may occur. Although the definition of a specific threshold to define clinical problems is difficult due to a lack of sensitivity, the systemic metal concentration is frequently measured clinically. Currently a threshold for cobalt and chromium between 4 µg/l and 7 µg/l is under debate. Very high levels (??20 µg/l) or a steady increase over time should be a warning sign; however, metal ion levels should not be interpreted as a single diagnostic tool but rather in the entire context of the clinical, radiological and cross-sectional imaging, metal artefact reduction sequence (MARS) magnetic resonance imaging (MRI), ultrasound and computed tomography (CT) findings. PMID:23842780

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

2013-08-01

216

Manufacturing Process for Alloys of Rare-Earth Metals and the System Used in This Manufacturing Process.  

National Technical Information Service (NTIS)

The present invention concerns a process by which a dissolved-salt bath containing rare-earth metals, alkali metals and the fluorides of alkaline-earth metals, is used to manufacture alloys of rare-earth metals and metals that have a melting point and a s...

T. Yamanaka

1988-01-01

217

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

218

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

PubMed

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. When maize entered the vigorous vegetation growth stage (e.g. early stem-elongation stage), rare earth-containing fertilizer was applied to the soil with irrigation water. At 10 days after application of the rare earths, significantly dose-dependent accumulative effects of individual rare earth concentrations in the roots and the plant tops of maize were observed, with the exception of Sc and Lu. At the level of 2 kg rare earths ha(-1), accumulative concentrations of most light rare earths (e.g. La, Ce, Pr and Nd) and Gd in the plant tops were much larger than those in the control. Concentrations of individual rare earths in a field-grown maize after application of rare earths decreased in the order of root>leaf>stem>grain. During the maize growth period, selective accumulation of individual rare earths (e.g. La, Ce) in the roots seemed to be in dynamic equilibrium, and the distribution of these elements in the plant tops was variable. At a dosage of less than 10 kg rare earths ha(-1), no apparent accumulative concentrations of individual rare earths appeared in the maize grains. Under the experimental conditions, application of rare earth-containing fertilizer did not induce an increase in the concentrations of heavy metals in the grains. We conclude that the present dosage of rare earths (<0.23 kg ha(-1) year(-1)) currently applied in China can hardly affect the safety of maize grains in arable soil, even over a long period. PMID:12109484

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

2002-07-01

219

Modification of metallic materials and hard coatings using metal ion implantation  

Microsoft Academic Search

Ion implantation, with doses in the range 1016 to 1018 ioncm-2, modifies the surface properties of many metallic and ceramic materials. Whilst gas ion beams are currently employed extensively, metal ion implantation (MII) systems have been developed based on the vacuum metal arc and a brief review of these systems is presented. Examples of industrial applications are given using, primarily,

Yurii P Sharkeev; Boris P Gritsenko; Sergei V Fortuna; Anthony J Perry

1999-01-01

220

Production of highly charged metal ion beams from organic metal compounds at RIKEN 18 GHz ECRIS  

Microsoft Academic Search

Intense beams of highly charged metal ions (e.g., 80 ?A for Fe13+) are successfully extracted from the 18 GHz ECR Ion Source at RIKEN by feeding vapors of organic metal compounds at room temperature into the ECR plasma chamber: by MIVOC method. The beam intensity of particular metal ion is strongly dependent on the microwave power and served compounds.

T. Nakagawa; J. Ärje; Y. Miyazawa; M. Hemmi; T. Chiba; N. Inabe; M. Kase; T. Kageyama; O. Kamigaito; A. Goto; M. G Niimura; Y. Yano

1997-01-01

221

The Transport of Solar Ions Through the Earth's Magnetosphere  

NASA Technical Reports Server (NTRS)

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

Lennartsson, O. W.

1999-01-01

222

Accumulation of metal ions by pectinates  

NASA Astrophysics Data System (ADS)

The knowledge of the mechanisms which regulate the interactions of metal ions with partially methyl esterified linear polymers of ?-1,4 linked D-galacturonic acid units (pectinates), well represented in the root inner and outer apoplasm, is of great relevance to understand the processes which control their accumulation at the soil-root interface as well as their mobilization by plant metabolites. Accumulation of a metal by pectinates can be affected by the presence of other metals so that competition or distribution could be expected depending on the similar or different affinity of the metal ions towards the binding sites, mainly represented by the carboxylate groups. In order to better understand the mechanism of accumulation in the apoplasm of several metal ions, the sorption of Cd(II), Zn(II), Cu(II), Pb(II) and Cr(III) by a Ca-polygalacturonate gel, used as model of the soil-root interface, with a degree of esterification of 18% (PGAE1) and 65% (PGAE2) was studied at pH 3.0, 4.0, 5.0 and 6.0 in the presence of CaCl2 2.5 mM.. The results show that sorption increases with increasing both the initial metal concentration and pH. A similar sorption trend was evidenced for Cu(II) and Pb(II) and for Zn(II) and Cd(II), indicating that the mechanism of sorption for these two ionic couples is quite different. As an example, at pH 6.0 and an initial metal concentration equal to 2.0 mM, the amount of Cu(II) and Pb(II) sorbed was about 1.98 mg-1 of PGAE1 while that of Cd(II) and Zn(II) was about 1.2 mg-1. Cr(III) showed a rather different sorption trend and a much higher amount (2.8 mg-1of PGAE1 at pH 6.0) was recorded. The higher affinity of Cr(III) for the polysaccharidic matrix is attributable to the formation of Cr(III) polynuclear species in solution, as shown by the distribution diagrams obtained through the MEDUSA software. On the basis of these findings, the following affinity towards the PGAE1 can be assessed: Cr(III) > Cu(II) ? Pb(II) > Zn (II) ? Cd(II). Surprisingly, simultaneous sorption tests and SEM analyses indicate that a different mechanism regulates the sorption of Cu(II) and Pb(II) by PGAE1. In fact, the amount of Pb(II) sorbed (0.92 moles mg-1of PGAE1) by PGAE1 was nearly independent by the presence of Cu(II) ions, at least at the three different concentrations tested, that indicates a higher affinity of Pb(II). Such an aspect was further confirmed by exchange experiments. Samples of PGAE1 saturated with 1.96 moles mg-1of Cu(II) or 2.01 moles mg-1of Pb(II) were put in contact with 100 mL of solutions containing 97.3 moles of Pb(II) or 99.4 moles Cu(II), respectively. The exchange kinetics show that about 80% of Cu(II) was stochiometrically exchanged by Pb(II). In contrast, only about 10% of Pb(II) complexed by PGAE1 was exchanged by Cu(II). The kinetics of simultaneous sorption of all the metal ions tested indicate that Pb(II) is selectively sorbed by the PGAE1 gels. Cd(II) and Zn(II) show a similar affinity towards PGAE1. Thus, in the simultaneous presence of these ions, their selectivity towards this matrix follows the order: Pb > Cu > Cd ? Zn. Sorption of Cr(III) in the presence of the ions considered was not possible to carry out due to interference phenomena. The sorption of the same ions by 50 mg of PGAE2 evidences that the amount of Cu(II), Pb(II), and Cr(III) sorbed is markedly lower than that found for PGAE1. By considering that two carboxylic groups are involved in the complexation of a metal ion, the data show that such a stoichiometry is respected only for Pb(II). The amount of Cu(II) sorbed is about 50% lower than that of Pb(II) at all the pH values tested whereas those of Zn(II) and Cd(II) are negligible whereas that of Cr(III) is the highest. The different behaviour of Cu(II) compared to Pb(II) can be explained taking into account for both hydrophobic and steric effects of the methyl groups as well as to their different charge density. Thus, it can be concluded that the accumulation of metals at the soil-root interface strictly depends on the esterification degree of the root p

Deiana, S.; Deiana, L.; Palma, A.; Premoli, A.; Senette, C.

2009-04-01

223

Sputtered metal cluster ions: Unimolecular decomposition and collision induced fragmentation  

Microsoft Academic Search

Cluster ions are produced by ion bombardment of thick metal targets and mass selected in a Wien filter. The unimolecular decomposition of Aln+, Cun+, Mon+, Wn+, and Pbn+ is investigated under UHV conditions. The time evolution of the decay allows a glimpse into the cluster formation\\/fragmentation process. Highly excited metal cluster ions decompose mainly by evaporating single neutral atoms with

W. Begemann; S. Dreihöfer; K. H. Meiwes-Broer; H. O. Lutz

1986-01-01

224

Several Kinds of Aminoxyl Radicals and their Metal Ion Complexes  

Microsoft Academic Search

Recent results of magnetization, magnetic susceptibility and muon spin rotation\\/relaxation (?SR) measurements of some organic neutral radicals based on aminoxyl and their anion radical complexes with alkali and transition metal cations are reported. Ferromagnetic intermolecular interactions, coexistent with antiferromagnetic ones, in several carboxyaryl nitronyl nitroxide radicals are affected by inserting alkali metal ions, while the incorporation of transition metal ions

Tadashi Sugano; Stephen J. Blundell; Francis L. Pratt; Thomas Jestädt; Brendon W. Lovett; William Hayes; Peter Day

1999-01-01

225

Neutral alkaline-metal and alkaline-earth-metal derivatives of imidazole and benzimidazole.  

PubMed

A theoretical study of the minima and connecting transition states of the neutral complexes formed by alkaline-metal and alkaline-earth-metal derivatives of imidazolate and benzimidazolate anions has been carried out using B3LYP/6-31+G(d,p), B3LYP/6-311+G(3df,2p), and G3B3 methods. Two and three nondegenerated minima and two and four TS structures have been identified for imidazole and benzimidazole derivatives, respectively. The most stable minima of the alkaline-metal derivatives of both systems correspond to the metal interacting with the imidazole ring, whereas in the alkaline-earth-metal derivatives, the preferred minima depend on the substituent. A remarkable feature of some minima is the fact that some of the metal-aromatic interactions follow the classical ?-cation pattern, even though the global structure corresponds to a neutral salt, constituting a class of noncovalent interaction of great interest in the chemistry of aromatic and heterocyclic complexes. A CSD search has confirmed that the two bonding modes, N-? and ?, are present in the solid phase. The ? mode has been analyzed by comparison with other azoles. PMID:24844848

Blanco, Fernando; Lloyd, David G; Alkorta, Ibon; Elguero, José

2014-06-12

226

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.

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

2012-01-01

227

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

228

Photoluminescence of polycrystalline zinc oxide co-activated with trivalent rare earth ions and lithium. Insertion of rare-earth ions into zinc oxide  

Microsoft Academic Search

The photoluminescence of polycrystalline sintered ZnO codoped with Li+ and trivalent rate-earth (RE3+) ions (Dy3+, Er3+, Eu3+, Ho3+, Nd3+, Sm3+ and Tm3+) has been studied. The luminescence spectra depend upon the nature of the rare earth. The UV excitation of the Eu3+-, Dy3+-, Sm3+-and Tm3+-doped samples induces the luminescence of the RE3+ ions: in addition to the broad ZnO pattern,

S. Bachir; K. Azuma; J. Kossanyi; P. Valat; J. C. Ronfard-Haret

1997-01-01

229

The NRAMP family of metal-ion transporters.  

PubMed

The family of NRAMP metal ion transporters functions in diverse organisms from bacteria to human. NRAMP1 functions in metal transport across the phagosomal membrane of macrophages, and defective NRAMP1 causes sensitivity to several intracellular pathogens. DCT1 (NRAMP2) transport metal ions at the plasma membrane of cells of both the duodenum and in peripheral tissues, and defective DCT1 cause anemia. The driving force for the metal-ion transport is proton gradient (protonmotive force). In DCT1 the stoichiometry between metal ion and proton varied at different conditions due to a mechanistic proton slip. Though the metal ion transport by Smf1p, the yeast homolog of DCT1, is also a protonmotive force, a slippage of sodium ions was observed. The mechanism of the above phenomena could be explained by a combination between transporter and channel mechanisms. PMID:16908340

Nevo, Yaniv; Nelson, Nathan

2006-07-01

230

Mechanisms of metal ion-coupled electron transfer.  

PubMed

Redox inactive metal ions acting as Lewis acids can control electron transfer from electron donors (D) to electron acceptors (A) by binding to radical anions of electron acceptors which act as Lewis bases. Such electron transfer is defined as metal ion-coupled electron transfer (MCET). Mechanisms of metal ion-coupled electron transfer are classified mainly into two pathways, i.e., metal ion binding to electron acceptors followed by electron transfer (MB/ET) and electron transfer followed by metal ion binding to the resulting radical anions of electron acceptors (ET/MB). In the former case, electron transfer and the stronger binding of metal ions to the radical anions occur in a concerted manner. Examples are shown in each case to clarify the factors to control MCET reactions in both thermal and photoinduced electron-transfer reactions including back electron-transfer reactions. PMID:22596095

Fukuzumi, Shunichi; Ohkubo, Kei; Morimoto, Yuma

2012-05-17

231

Semicondutor quantum dots-based metal ion probes.  

PubMed

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. PMID:24270674

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

2014-01-01

232

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

233

Binuclear phthalocyanine-based sandwich-type rare earth complexes: unprecedented two ?-bridged biradical-metal integrated SMMs.  

PubMed

Mini-magnets: Sandwich-type rare earth complexes involving two fused bis(phthalocyaninato) dysprosium(III) units, represent the first example of biradical-metal single molecule magnets (SMMs). These materials were synthesized and structurally characterized. Comparative investigation reveals the effective suppression of quantum tunneling of magnetization (QTM) by the ?-bridged biradical-based antiferromagnetic interaction in the di-dysprosium-ion-based SMM. PMID:23843166

Wang, Kang; Qi, Dongdong; Wang, Hailong; Cao, Wei; Li, Wenjun; Liu, Tao; Duan, Chunying; Jiang, Jianzhuang

2013-08-19

234

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

235

Heavy water reactions with alkaline-earth metal dications in the gas phase: Kinetics at room temperature  

Microsoft Academic Search

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

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

2009-01-01

236

Photoluminescent graphene oxide microarray for multiplex heavy metal ion analysis.  

PubMed

An aptamer-linked graphene oxide (GO) microarray is synthesized for multiplex heavy metal ion detection. Fluorescent nanosized GO sheets are micropatterned, and specific aptamers targeting Ag(+) and Hg(2+) are immobilized on the GO array. Upon capture of the target heavy metal ions, electron transfer occurs between the GO (donors) and the heavy metal ions (acceptors), leading to fluorescence quenching of the GO. PMID:23606642

Liu, Fei; Ha, Hyun Dong; Han, Dong Ju; Seo, Tae Seok

2013-10-25

237

Optical methods for the detection of heavy metal ions  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

238

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

239

Research on Multi-Ion Interactions and Defects in Metals.  

National Technical Information Service (NTIS)

A summary of research on multi-ion interactions is presented. Emphasis is placed on point defects in nontransition metals and the calculation of screening charge densities, electric field gradients and lattice distortion. Multi-ion interactions in transit...

R. E. Beissner

1982-01-01

240

Witnessing spin-orbit thermal entanglement in rare-earth ions  

NASA Astrophysics Data System (ADS)

We explore spin-orbit thermal entanglement in rare-earth ions, based on a witness obtained from mean energies. The entanglement temperature TE, below which entanglement emerges, is found to be thousands of kelvins above room temperature for all light rare earths. This demonstrates the robustness to environmental fluctuations of entanglement between the internal degrees of freedom of a single ion.

Duarte, O. S.; Castro, C. S.; Soares-Pinto, D. O.; Reis, M. S.

2013-08-01

241

Lattice Location of Rare Earth Ions in Semiconductors: Interpretation and Limitations of using g values  

Microsoft Academic Search

The g values of rare earth ions obtained from either paramagnetic resonance or Zeeman measurements are often used to interpret the location and\\/or environment surrounding rare earth ions. In the case of centres with cubic symmetry the g value can be used to distinguish between substitutional and interstitial sites. For centres with less than cubic symmetry the average g value,

David Carey

242

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

SciTech Connect

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

Yasukawa, Akemi, E-mail: yasukawa@cc.hirosaki-u.ac.jp [School of Home Economics, Faculty of Education, Hirosaki University, 1-bunkyo, Hirosaki, Aomori 036-8560 (Japan)] [School of Home Economics, Faculty of Education, Hirosaki University, 1-bunkyo, Hirosaki, Aomori 036-8560 (Japan); Kandori, Kazuhiko [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan)] [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan); Tanaka, Hidekazu [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan)] [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Gotoh, Keiko [Faculty of Human Life and Environment, Nara Women's University, Kita-uoya-nishi, Nara 630-8506 (Japan)] [Faculty of Human Life and Environment, Nara Women's University, Kita-uoya-nishi, Nara 630-8506 (Japan)

2012-05-15

243

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

244

THE ROLES OF METAL IONS IN REGULATION BY RIBOSWITCHES  

PubMed Central

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

2012-01-01

245

Thermodynamics and pair structures of liquid alkali and alkaline-earth metals from the perturbative hypernetted-chain equation  

NASA Astrophysics Data System (ADS)

We have theoretically studied liquid alkali and alkaline-earth metals by combining the second-order pseudopotential (PP) theory of ion-electron interaction and a statistical mechanical method for calculating ionic thermal motion. The latter is done by utilizing the perturbative hypernetted-chain equation recently proposed by the author. The PP is modelled through an ab initio method presented by Shaw, i.e., through the use of the optimized nonlocal model potential (OMP). Calculations are carried out with two different methods for extracting parameters in the OMP. They are due to Animalu and Heine (AH), and Ballentine and Gupta (BG). Results show that both of thermodynamic properties and pair structures are in good agreements with experimental data for alkali metals with the AH set of parameters. For alkaline-earth metals other than Ba, calculations with the BG set give the radial distributions and structure factors in good agreement with experimental data.

Seok Kang, Hong

1999-09-01

246

Design and synthesis of metal ion-recognition-induced conjugated polymers: An approach to metal ion sensory materials  

Microsoft Academic Search

The synthesis and metal ion responsive properties of two 2, 2`-bipyridyl-phenylene-vinylene-based polymers is reported. These polymers are designed to be partially conjugated in their metal-free state and fully conjugated when exposed to metal ions so that the ion-induced conjugation enhancement can be transduced into a measurable signal. It is found that these polymers exhibit highly ionochromic effects with a wide

Bing Wang; Michael R. Wasielewski

1997-01-01

247

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

248

Plasma immersion ion implantation for reducing metal ion release  

NASA Astrophysics Data System (ADS)

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

Díaz, C.; García, J. A.; Mändl, S.; Pereiro, R.; Fernández, B.; Rodríguez, R. J.

2012-11-01

249

Plasma immersion ion implantation for reducing metal ion release  

SciTech Connect

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

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

2012-11-06

250

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

251

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

252

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

253

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

254

The rare-earth metals industry of Russia: Present status, resource conditions of development  

Microsoft Academic Search

The importance of rare-earth metals in the advancement of scientific and technological progress, the geographical features\\u000a characteristic for the development of the rare-earth sector in the world and in Russia, and the raw-material base of its development\\u000a in Russia are considered. Emphasis is placed on the special significance of the Tomtorskii composite rare-metal\\/rare earth\\u000a deposit in the Sakha Republic (Yakutia).

I. L. Savel’eva

2011-01-01

255

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

256

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

PubMed

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

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

2013-11-21

257

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

258

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

259

Rotational dynamics of metal azide ion pairs in dimethylsulfoxide solutions.  

PubMed

Azide ion is an excellent vibrational probe for studying ion-ion and ion-dipole interactions in solutions because its frequency is sensitively dependent on its local environments. When azide ion forms contact ion pairs with cations in dimethylsulfoxide (DMSO), free azide ion and contact ion pairs are spectrally well distinguished in FTIR spectra. Here, we investigated vibrational population relaxation, P(t), and orientational relaxation dynamics, r(t), of free azide ion and contact ion pairs (LiN3, NaN3, NH4N3, MgN3(+), and CaN3(+)) in DMSO by IR pump-probe spectroscopy. For metal azide ion pairs, the metal ion slowed down the vibrational relaxation of azide ion by acting like a thermal insulator. Biexponential behavior of r(t) was analyzed in the wobbling-in-a-cone model. The long time component of r(t) of free azide ion was found to be viscosity-dependent. The wobbling motion of azide ion within the frame of metal azide ion pairs was weakly dependent on the countercation. When the overall orientational relaxation of metal azide ion pairs was analyzed by the extended Debye-Stokes-Einstein equation, it was well described under stick or superstick boundary conditions due to a strong interaction between the metal ion and DMSO molecules. Our experimental results provide important insight in understanding the rotational dynamics of small ionic species in polar solvents when the size of the ionic species is smaller than or comparable to that of the solvent molecule. PMID:23409952

Son, Hyewon; Kwon, YoungAh; Kim, Jinwoo; Park, Sungnam

2013-03-01

260

Infrared and electron-paramagnetic-resonance spectra of trivalent rare-earth ions in hydrogenated strontium-fluoride crystals  

Microsoft Academic Search

Infrared measurements of hydrogenated strontium-fluoride crystals containing trivalent rare-earth ions, and EPR measurements of hydrogenated strontium-fluoride crystals containing gadolinium are reported. The infrared results show that the hydride ions associated with the rare-earth ions occur in several different sites whose relative occurrence changes abruptly in the vicinity of holmium. For the rare-earth ions before holmium in the rare-earth series, there

A. Edgar; C. A. Freeth; G. D. Jones

1977-01-01

261

Metal Ion Release With Large-Diameter Metal-on-Metal Hip Arthroplasty  

Microsoft Academic Search

Preoperative and postoperative ion concentrations were measured in 29 metal-on-metal, large-diameter head total hip arthroplasty (LDH-THA) patients. Mean chromium, cobalt (Co), and titanium levels from LDH-THA were 1.3, 2.2, and 2.7 ?g\\/L at 12 months. The open femoral head design showed significantly higher Co concentrations than the closed design (3.0 vs 1.8 ?g\\/L, P = .037). Compared with previously published

Pascal-André Vendittoli; Traian Amzica; Alain G. Roy; Daniel Lusignan; Julien Girard; Martin Lavigne

2011-01-01

262

Microbial metal-ion reduction and Mars: extraterrestrial expectations?  

Microsoft Academic Search

Dissimilatory metal-ion-reducing bacteria (DMRB) can couple the reduction of a variety of different metal ions to cellular respiration and growth. The excitement of this metabolic group lies not only in the elucidation of a new type of metabolism, but also in the potential use of these abilities for the removal of toxic organics, and in their ability to reduce (and

Kenneth H. Nealson; B. Lea Cox

2002-01-01

263

Vegetable waste-based sensors for metal ion determination  

Microsoft Academic Search

Last studies on metal adsorption have shown important interactions between different vegetable wastes and metal ions. Recently, yohimbe bark and grape stalks have been used as biosorption materials in the recovery and preconcentration of chromium(VI) ions. In the present work, both vegetable residues coming from pharmaceutical and wine industries, respectively, are selected for the development of vegetable waste-based sensors for

Núria Fiol; Florencio de la Torre; Patrick Demeyere; Antonio Florido; Isabel Villaescusa

2007-01-01

264

Immobilized Metal Ion Affinity Chromatography (IMAC) Chemistry and Bioseparation Applications  

Microsoft Academic Search

This review discusses the principles of immobilized metal ion affinity chromatography (IMAC) and its applications to protein separations. IMAC functions by binding the accessible electron-donating pendant groups of a protein - such as histidine, cysteine, and tryptophan - to a metal ion which is held by a chelating group covalently attached on a stationary support. A common chelating group is

Jon W. Wong; Robert L. Albright; Nien-Hwa L. Wang

1991-01-01

265

Metal ion release kinetics from nanoparticle silicone composites  

Microsoft Academic Search

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 30days of immersion, Fickian diffusion is the dominant transport mechanism. After this time period, the oxidation and

Anne Hahn; Gudrun Brandes; Philipp Wagener; Stephan Barcikowski

2011-01-01

266

Characterization of metal ion-nucleic acid interactions in solution.  

PubMed

Metal ions are inextricably involved with nucleic acids due to their polyanionic nature. In order to understand the structure and function of RNAs and DNAs, one needs to have detailed pictures on the structural, thermodynamic, and kinetic properties of metal ion interactions with these biomacromolecules. In this review we first compile the physicochemical properties of metal ions found and used in combination with nucleic acids in solution. The main part then describes the various methods developed over the past decades to investigate metal ion binding by nucleic acids in solution. This includes for example hydrolytic and radical cleavage experiments, mutational approaches, as well as kinetic isotope effects. In addition, spectroscopic techniques like EPR, lanthanide(III) luminescence, IR and Raman as well as various NMR methods are summarized. Aside from gaining knowledge about the thermodynamic properties on the metal ion-nucleic acid interactions, especially NMR can be used to extract information on the kinetics of ligand exchange rates of the metal ions applied. The final section deals with the influence of anions, buffers, and the solvent permittivity on the binding equilibria between metal ions and nucleic acids. Little is known on some of these aspects, but it is clear that these three factors have a large influence on the interaction between metal ions and nucleic acids. PMID:22210334

Pechlaner, Maria; Sigel, Roland K O

2012-01-01

267

Polyphosphazene membranes for metal ion separations  

SciTech Connect

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

Stone, M.L.

1996-05-01

268

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

269

Slow collisions of multicharged ions with metal surfaces  

SciTech Connect

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

Meyer, F.W.

1993-12-31

270

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

PubMed

Metal ions such as iron, copper, manganese, and zinc are essential nutrients for all eukaryotic microorganisms. Therefore, these organisms possess efficient uptake mechanisms to obtain these nutrients from their extracellular environment. Metal ions must also be transported into intracellular organelles where they function as catalytic and structural cofactors for compartmentalized enzymes. Thus, intracellular transport mechanisms are also present. When present in high levels, metal ions can also be toxic, so their uptake and intracellular transport is tightly regulated at both transcriptional and post-transcriptional levels to limit metal ion overaccumulation and facilitate storage and sequestration. Remarkable molecular insight into these processes has come from recent studies of the yeast Saccharomyces cerevisiae. This organism, which is the primary subject of this chapter, serves as a useful paradigm to understand metal ion metabolism in other eukaryotic microbes. PMID:10907553

Eide, D J

2000-01-01

271

Fulvic acid: modifier of metal-ion chemistry  

SciTech Connect

Fulvic acid, which is derived from the decay of plants and animals, is being studied for its role in the transport and toxicity of metal ions in soil and water. It is discussed in relation to the origin of humic substances and its interactions with metal ions. Techniques for investigating complexes of fulvic acid and metal ions are presented. They are separation and nonseparation analyses which are applied to speciation problems. The applicability, advantages, and disadvantages of both methods are presented. Separation of free and complexed metal ions can be done by chromatography, or with membranes that exclude the metal-ion complexes. Chromatographic techniques include liquid chromatography by size exclusion. Nonseparation techniques include voltametry and potentiometry, as well as fluorescence. A comparison of methods for calculation of the conditional stability constant K for complexes containing fulvic acid and copper (II) or cadmium (II) is presented.

Saar, R.A.; Weber, J.H.

1982-01-01

272

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

273

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

274

Lithium-Ion Batteries Being Evaluated for Low-Earth-Orbit Applications.  

National Technical Information Service (NTIS)

The performance characteristics and long-term cycle life of aerospace lithium-ion (Li-ion) batteries in low-Earth-orbit applications are being investigated. A statistically designed test using Li-ion cells from various manufacturers began in September 200...

B. I. McKissock

2005-01-01

275

Guided ion beam studies of reactions of alkaline earth ions with O2  

NASA Astrophysics Data System (ADS)

The endothermic reactions of Mg+ and Sr+ with O2 are studied in a guided ion beam mass spectrometer. Analysis of the reaction thresholds are used to obtain 0 K bond dissociation energies of MgO+ (2.50 ± 0.10 eV) and SrO+ (3.47 ± 0.06 eV), which are compared with other literature values. Analysis of these reaction cross sections and those previously published for the reaction of Ca+ with O2 [E.R. Fisher, J.L. Elkind, D.E. Clemmer, R. Georgiadis, S.K. Loh, N. Aristov, L.S. Sunderlin, and P.B. Armentrout, J. Chem. Phys., 93 (1990) 2676] suggests that there are both thermodynamic and impulsive reaction pathways. The latter play an increasingly important role in the reaction dynamics as the mass of the alkaline earth ion increases.

Dalleska, N. F.; Armentrout, P. B.

1994-06-01

276

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

277

Ion-beam-deposited ultrathin transparent metal contacts  

Microsoft Academic Search

Using ion-beam sputtering we have prepared ultrathin transparent metal contacts with large broad-band optical transmittance and low electrical sheet resistance. Metal films deposited by ion-beam sputtering have exceptionally small surface roughness, and films as thin as about 20 Å are continuous and conductive, and provide optical transmittance as large as 80%. Ultrathin transparent metal contacts provide a number of advantages

Hagen Klauk; Jiunn-Ru Huang; Jonathan A Nichols; Thomas N Jackson

2000-01-01

278

The NRAMP family of metal-ion transporters  

Microsoft Academic Search

The family of NRAMP metal ion transporters functions in diverse organisms from bacteria to human. NRAMP1 functions in metal transport across the phagosomal membrane of macrophages, and defective NRAMP1 causes sensitivity to several intracellular pathogens. DCT1 (NRAMP2) transport metal ions at the plasma membrane of cells of both the duodenum and in peripheral tissues, and defective DCT1 cause anemia. The

Yaniv Nevo; Nathan Nelson

2006-01-01

279

Mechanism of metal ion biosorption by fungal biomass  

Microsoft Academic Search

Alkali extracted mycelial biomass from Aspergillus niger, referred to as Biosorb, was found to sequester metal ions (Cd2+, Cu2+, Zn2+, Ni2+ and Co2+) efficiently both from dilute and concentrated solutions upto 10% of its weight (w\\/w). Sequestration of metal ions from a mixture was also efficient but with attendant antagonisms. The kinetics of metal binding by Biosorb indicated that it

K. Sivarama Sastry; P. Maruthi Mohan

1996-01-01

280

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.

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

2002-01-01

281

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

282

Aspects on metal ion distribution models in pulp washing simulation  

Microsoft Academic Search

The closure of the liquid system in a pulp mill has increased the concentration of metal ions in the process as compared to traditional plants. These ions commonly referred to as non-process elements, NPE, enter the pulp mill with the wood chips, the water supply and the pulping chemicals. The presence of these ions may lead to various problems, e.g.

Karin Mattsson; Gunnar Eriksson; Urban Grén; Krister Ström

2007-01-01

283

Gas-Phase Ion/Ion Reactions of Multiply Protonated Polypeptides with Metal Containing Anions  

PubMed Central

Gas-phase reactions of multiply protonated polypeptides and metal containing anions represent a new methodology for manipulating the cationizing agent composition of polypeptides. This approach affords greater flexibility in forming metal containing ions than commonly used methods, such as electrospray ionization of a metal salt/peptide mixture and matrix-assisted laser desorption. Here, the effects of properties of the polypeptide and anionic reactant on the nature of the reaction products are investigated. For a given metal, the identity of the ligand in the metal containing anion is the dominant factor in determining product distributions. For a given polypeptide ion, the difference between the metal ion affinity and the proton affinity of the negatively charged ligand in the anionic reactant is of predictive value in anticipating the relative contributions of proton transfer and metal ion transfer. Furthermore, the binding strength of the ligand anion to charge sites in the polypeptide correlates with the extent of observed cluster ion formation. Polypeptide composition, sequence, and charge state can also play a notable role in determining the distribution of products. In addition to their usefulness in gas-phase ion synthesis strategies, the reactions of protonated polypeptides and metal containing anions represent an example of a gas-phase ion/ion reaction that is sensitive to polypeptide structure. These observations are noteworthy in that they allude to the possibility of obtaining information, without requiring fragmentation of the peptide backbone, about ion structure as well as the relative ion affinities associated with the reactants.

Newton, Kelly A.; Amunugama, Ravi; McLuckey, Scott A.

2005-01-01

284

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

Microsoft Academic Search

Quantitative structure-activity relationships have been used to predict the relative toxicity of organic compounds. Although not as common, ion characteristics have also proven useful for predicting the relative toxicity of metal ions. The purpose of this study was to determine if the relative toxicity of metal ions using the Microtox{reg_sign} bioassay was predictable using ion characteristics. Median effect concentrations (EC50s)

John T. McCloskey; Michael C. Newman; Sue B. Clark

1996-01-01

285

Ion exchange of some heavy metal ions from polar organicsolvents into zeolite  

Microsoft Academic Search

In the present study the possibility of ion exchange of heavy metal ions using polar organic solvents and naturalzeolite clinoptilolite is approached. The organic solvents used are nearly pure ethanol and acetone. These solventsare compared to deionized water. The heavy metal ions studied are Cu2+, Cr3+ and Fe3+. While ion exchange levelsin water are much greater for Fe3+ (53.1%) in

V. J. Inglezakis; M. D. Loizidou

2007-01-01

286

Ion efflux systems involved in bacterial metal resistances  

Microsoft Academic Search

Summary Studying metal ion resistances gives us important insights into environmental processes and provides an understanding of basic living processes. This review concentrates on bacterial efflux systems for inorganic metal cations and anions, which have generally been found as resistance systems from bacteria isolated from metal-polluted environments. The protein products of the genes involved are sometimes prototypes of new families

Dietrich H. Nies; Simon Silver

1995-01-01

287

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

PubMed

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(2) at an extraction voltage of 45 kV and a first gap spacing of 12 mm. PMID:20192429

Oks, Efim; Anders, André

2010-02-01

288

Evidence of strong energetic ion acceleration in the near-Earth magnetotail  

NASA Astrophysics Data System (ADS)

now it is still questionable whether ions are accelerated to energies above 100 keV in the near-Earth current sheet (CS), in the vicinity of a possible near-Earth neutral line. By using 11 years of 3-D energetic ion flux data for protons, helium, and oxygen (~150 keV-1 MeV) from the RAPID instrument on board Cluster 4, we statistically study the energetic ion acceleration by investigating ion anisotropies in the near-Earth magnetotail (-20 RE < X <-16 RE). It is found that the earthward (tailward) anisotropy of the energetic (>150 keV) ions (protons, He+, and O+) tend to become higher as the earthward (tailward) plasma bulk flows (measured by Cluster Ion Spectrometry experiment) become stronger. During such periods the presence of a strong acceleration source tailward (earthward) of Cluster spacecraft (S/C) is confirmed by the hardening energy spectra of the earthward (tailward) energetic ion flows. A good statistical correlation between tailward bulk flow, negative Bz, and the tailward anisotropy of energetic ions indicates that the strong ion acceleration might be related to a near-Earth reconnection, which occurred earthward of the Cluster S/C. The energetic ion anisotropies do not show a clear dependence on the AE index, which may indicate that the acceleration source(s) for the energetic ions could be spatially localized.

Luo, H.; Kronberg, E. A.; Grigorenko, E. E.; Fränz, M.; Daly, P. W.; Chen, G. X.; Du, A. M.; Kistler, L. M.; Wei, Y.

2014-06-01

289

When VSEPR Fails: Experimental and Theoretical Investigations of the Behavior of Alkaline-Earth-Metal Acetylides  

PubMed Central

The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline-earth-metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl-substituted alkaline-earth-metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline-earth-metal chemistry.

Guino-o, Marites A.; Alexander, Jacob S.; McKee, Michael L.; Hope, Hakon; Englich, Ulrich B.

2014-01-01

290

A general two-metal-ion mechanism for catalytic RNA.  

PubMed Central

A mechanism is proposed for the RNA-catalyzed reactions involved in RNA splicing and RNase P hydrolysis of precursor tRNA. The mechanism postulates that chemical catalysis is facilitated by two divalent metal ions 3.9 A apart, as in phosphoryl transfer reactions catalyzed by protein enzymes, such as the 3',5'-exonuclease of Escherichia coli DNA polymerase I. One metal ion activates the attacking water or sugar hydroxyl, while the other coordinates and stabilizes the oxyanion leaving group. Both ions act as Lewis acids and stabilize the expected pentacovalent transition state. The symmetry of a two-metal-ion catalytic site fits well with the known reaction pathway of group I self-splicing introns and can also be reconciled with emerging data on group II self-splicing introns, the spliceosome, and RNase P. The role of the RNA is to position the two catalytic metal ions and properly orient the substrates via three specific binding sites.

Steitz, T A; Steitz, J A

1993-01-01

291

Metal ion coordination studies on a silica-based ion exchange resin before and after heating.  

SciTech Connect

Work designed to assess the potential of using a single material to sorb highly charged metal ions from aqueous solution and then microencapsulate and chemical fix those sorbed metal ions in vitreous silica is described. The basis for these studies is a chemically functionalized porous silica that is termed Diphosil. Diphosil was created by Chiarizia and coworkers (Solv. Extr. Ion Exch. 1996, 14(6), 1977-1100) as an ion exchange resin that strongly sorbs actinide and other highly charged metal ions from acid solutions. We have determined the maximum metal ion loading for Diphosil and shown that it sorbs trivalent ions from concentrated phosphoric acid. Using FT-IR analysis, we have shown that heating metal ion-loaded Diphosil in air converts its organic content primarily into carbon dioxide and water vapor. We have carried out studies on luminescence dynamics and spectroscopy, powder x-ray diffraction, and optical microscopy of metal ion-loaded Diphosil prior to and following heating in air. All of the results of our investigations are consistent with microencapsulation and chemical fixation of metal ions sorbed into Diphosil when that material is heated to 1273 K. In consequence, Diphosil is a promising basis for a single material approach to reducing nuclear waste volume by removing longlived alpha emitters from high level liquid radioactive waste and generating a vitreous silica nuclear waste form for the removed radionuclides that is suitable for geologic disposal.

Beitz, J. V.; Williams, C. W.; Chemistry

2001-07-31

292

Cesium Ion Bombardment of Metal Surfaces  

NASA Astrophysics Data System (ADS)

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

Tompa, Gary S.

293

Heavy-Ion-Induced Fission in the Rare-Earth Region and the Statistical Model.  

National Technical Information Service (NTIS)

Two separate aspects of heavy-ion-induced fission in the rare-earth region are considered. First, fission excitation functions and their relationship to fission barriers are considered. Second, results on neutron emission associated with fission are brief...

F. Plasil J. R. Beene B. Cheynis R. L. Ferguson F. E. Obenshain

1982-01-01

294

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

295

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 conelike 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 in this paper.

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

1978-01-01

296

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

2014-06-01

297

Luminescence and charge compensation in SnO2 doped with rare-earth ions  

Microsoft Academic Search

Tin oxide has been doped with several of the rare-earth ions, namely europium, terbium, thulium, holmium and neodymium. The effects of coactivators such as lithium, phosphorus and niobium have been investigated as well. Of the rare-earth ions, only europium, terbium and thulium plus coactivator, when added to tin oxide, caused the characteristic RE3+ lines in the visible region of the

D. F. Crabtree

1978-01-01

298

Persistent luminescence in rare earth ion-doped gadolinium oxysulfide phosphors  

Microsoft Academic Search

A series of rare-earth ion-doped gadolinium oxysulfide phosphors Gd2O2S:RE3+, Ti, Mg (RE=Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) were synthesized by solid-state reaction. The excitation and photoluminescence spectra, afterglow spectra, afterglow decay curves and thermoluminescence spectra of the phosphors were examined. According to the afterglow spectra, gadolinium oxysulfide doped with rare-earth ions were classified into three

Bingfu Lei; Yingliang Liu; Junwen Zhang; Jianxin Meng; Shiqing Man; Shaozao Tan

2010-01-01

299

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

300

Metal ion levels decrease after revision for metallosis arising from large-diameter metal-on-metal hip arthroplasty.  

PubMed

Concerns have been renewed regarding the possible long-term effects of elevated circulating levels of cobalt and chromium as a direct result of implantation of large femoral head diameter metal-on-metal bearings. In order to establish whether metal ion levels remain persistently elevated, we compared metal ion levels before and after revision surgery in patients with large head diameter (greater than 38 mm) metal-on-metal total hip arthroplasty or hip resurfacing arthroplasty. At greater than one year post removal of a large-diameter metal-on-metal hip implant for the indication of symptomatic metallosis, metal ion levels were found to fall to almost normal levels. PMID:22308623

Ebreo, Darren; Khan, Abdul; El-Meligy, Mohammed; Armstrong, Catherine; Peter, Viju

2011-12-01

301

Influences of peptide side chains on the metal ion binding site in metal ion-cationized peptides: Participation of aromatic rings in metal chelation  

Microsoft Academic Search

Aromatic side chains on amino acids influence the fragmentations of cationic complexes of doubly charged metal ions and singly\\u000a deprotonated peptides. The metal ion interacts with an aromatic side chain and binds to adjacent amide nitrogens. When fragmentation\\u000a occurs, this bonding leads to the formation of abundant metal-containing a-type ions by reactions that occur at the sites\\u000a of amino acids

Peifeng Hu; Curt Sorensen; Michael L. Gross

1995-01-01

302

Magnetization of Compounds of Rare Earths with Platinum Metals  

Microsoft Academic Search

Measurements have been made of the Curie points and magnetic moments of three series of compounds (Laves phases) MIr2, MOs2, and MRu2, where M is a rare-earth element. The Curie point is highest (85°K) for the compounds containing Gd and falls away when the rare earths have larger or smaller atomic numbers. This dependence of Curie point on the rare-earth

R. M. Bozorth; B. T. Matthias; H. Suhl; E. Corenzwit; D. D. Davis

1959-01-01

303

Minerals yearbook, 1988. Rare-earth minerals and metals  

Microsoft Academic Search

Domestic production of rare-earth concentrates decreased in 1988. Foreign sources of processed rare earths obtained a slightly larger share of the U.S. market, while domestic exports saw a marked increase compared to 1987 levels. Rare earths were used in high-technology applications such as laser crystals, high-strength permanent magnets, optical fibers, magnetic resonance imaging (MRI) scanners, and high-temperature superconductors. Topics discussed

J. B. Hedrick; D. A. Templeton

1988-01-01

304

Metal ion levels: how can they help us?  

PubMed

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

Griffin, William L

2014-04-01

305

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.

Cassat, James E.

2013-01-01

306

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

307

Amphipathic cyclooctapeptides: interactions with detergent micelles and metal ions  

NASA Astrophysics Data System (ADS)

In order to study the secondary structural preferences of amphipathic cyclopeptides in detergent assemblies and their interactions with metal ions, two basic amphiphatic cyclooctapeptides, c[(Lys- D-Lys) 2-Xaa- D-Leu-Leu- D-Leu], where Xaa is Leu ( P1) or Trp ( P2), were studied by circular dichroism (CD) spectroscopy. In water, P1 exhibited an unordered secondary structure whereas P2 adopted a partial ?-sheet structure. Temperature effect on the CD of these cyclopeptides showed small changes over the temperature range from 278 to 353 K. P1 showed low and non-specific binding affinity for metal ions (Ca 2+, Zn 2+, Na +, or Li +) in water whereas P2 did not exhibit any significant interaction with these ions. However, in the zwitterionic micellar detergent dodecylphosphocholine (DPC), P2 adopted a ?-sheet structure, which exhibited a greater propensity for metal ion interactions (K 1˜10 3 M -1 and K2˜10 2 M -1). Variable temperature CD studies on the peptide-metal ion complexes showed that these interactions are thermally reversible. Our results indicate that amphipathic cyclooctapeptides can co-assemble with micellar DPC and are capable of interacting with metal ions. This study will improve our ability to design a better metal ion sensing cyclopeptide in co-micellar assembles.

Gates, William Day; Rostas, Jack; Kakati, Bobby; Ngu-Schwemlein, Maria

2005-01-01

308

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

309

Rare-Earth Transition-Metal Intermetallics. Structure Bonding Property Relationships.  

National Technical Information Service (NTIS)

The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the ...

M. K. Han

2006-01-01

310

A thermodynamic "vocabulary" for metal ion interactions in biological systems.  

PubMed

This Account focuses on metal ion-ligand complexes of biological relevance and measurements of the bond dissociation energies (BDEs) of such species. These complexes yield thermochemistry that begins to provide a thermodynamic "vocabulary" for thinking quantitatively about the strength of interactions in biological systems. The method utilized is threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. Accurate determination of BDEs requires attention to many details of the experiments and data analysis, as outlined here. Trends in metal ion-ligand BDEs are examined as a function of the metal ion, ligand, and extent of ligation. We elucidate the importance of ion-dipole and ion-induced dipole interactions, chelation, conformation, tautomeric form, steric interactions, and electronic effects such as hybridization and promotion. Interactions of metal ions with nucleobases and amino acids are quantified and the effects of hydration on these values are explored for the amino acid systems. Although data limitations restrict the present discussion to monocations, the trends elucidated here should be relevant to multiply charged metal ions, for which data is forthcoming. PMID:15609991

Rodgers, M T; Armentrout, P B

2004-12-01

311

Femoral Head Size Does Not Affect Ion Values in Metal-on-Metal Total Hips  

Microsoft Academic Search

Background  Metal-on-metal articulations can release substantial amounts of particles containing cobalt and chromium into the surrounding\\u000a milieu, causing concern for cellular toxicity and adverse local soft tissue reactions. The diameter of the femoral head has\\u000a been one of the variables that inversely affects wear of metal-on-metal total hip arthroplasty (THA). The oxidative stress\\u000a of increased metal ions can be measured with

Mitchell Bernstein; Alan Walsh; Alain Petit; David J. Zukor; John Antoniou

2011-01-01

312

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

Microsoft Academic Search

Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active\\u000a patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We\\u000a hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had\\u000a metal-on-metal hip resurfacing (Group A; average head

Antonio Moroni; Lucia Savarino; Matteo Cadossi; Nicola Baldini; Sandro Giannini

2008-01-01

313

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

314

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

315

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

316

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

317

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

318

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

319

Main Group Metal Ion Chemistry In Planetary Atmospheres  

NASA Astrophysics Data System (ADS)

Metal ions are a significant product of meteoric ablation within planetary atmospheres. The lifetimes and ultimate chemical processing of these metal ions depend crucially on their association chemistry with the dominant atmospheric constituents (variously N2, CO2, and H2 among the Solar System's representative planetary atmospheres), yet this association chemistry has received very little previous study. In this work we present, for the first time, calculated temperature-dependent termolecular association rate coefficients for the reactions of the dominant main-group metal ions Na+, Mg+, Al+, K+, and Ca+ with N2, CO2, and H2. These rate coefficients have been determined through the use of variational transition state theory, employing structural and thermochemical data obtained via ab initio quantum chemical calculations. Implications of the calculated kinetic data, for a few specific instances of meteoric metal-ion chemistry, are sketched out, and directions for future study are also outlined.

Petrie, Simon; Dunbar, Robert C.

2006-09-01

320

Extracting metal ions with diphosphonic acid, or derivative thereof  

SciTech Connect

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

321

An engineered palette of metal ion quenchable fluorescent proteins.  

PubMed

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

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

2014-01-01

322

An Engineered Palette of Metal Ion Quenchable Fluorescent Proteins  

PubMed Central

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

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

2014-01-01

323

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

324

Frictional and morphological characteristics of ion plated soft, metallic films  

NASA Technical Reports Server (NTRS)

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

Spalvins, T.; Buzek, B.

1981-01-01

325

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

326

Energization of solar wind ions by reflection from the earth's bow shock  

Microsoft Academic Search

The existence of ion beams with energies a few times the solar wind energy and streaming outward from the earth's bow shock has been known for some time. To explain the observed ion energies, a simple reflection model has been proposed in which the particles gain energy by displacement parallel to the interplanetary electric field. In this model the energy

G. Paschmann; N. Sckopke; J. R. Asbridge; S. J. Bame; J. T. Gosling

1980-01-01

327

Divalent cerium and praseodymium ions in crystals of alkaline-earth fluorides  

NASA Astrophysics Data System (ADS)

We have studied the absorption spectra of radiation-induced divalent cerium and praseodymium ions in crystals of alkaline-earth fluorides. Using ab initio quantum-mechanical methods, we have calculated absorption spectra of divalent praseodymium ions in CaF2 crystals for the first time. The theoretical spectrum agrees rather well with the experimentally registered spectra.

Shendrik, R. Yu.; Myasnikova, A. S.; Egranov, A. V.; Radzhabov, E. A.

2014-05-01

328

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

SciTech Connect

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

Vohra, Yogesh K.; Sangala, Bagvanth Reddy; Stemshorn, Andrew K. [Physics, University of Alabama at Birmingham (UAB), 310 Campbell Hall, 1300 University Boulevard, Birmingham, AL, 35294-1170 (United States); Hope, Kevin M. [Biology, Chemistry, and Mathematics, University of Montevallo, Harman Hall, Station 6480, Montevallo, AL, 35115 (United States)

2008-07-01

329

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

330

Metal Ion release with large-diameter metal-on-metal hip arthroplasty.  

PubMed

Preoperative and postoperative ion concentrations were measured in 29 metal-on-metal, large-diameter head total hip arthroplasty (LDH-THA) patients. Mean chromium, cobalt (Co), and titanium levels from LDH-THA were 1.3, 2.2, and 2.7 ?g/L at 12 months. The open femoral head design showed significantly higher Co concentrations than the closed design (3.0 vs 1.8 ?g/L, P = .037). Compared with previously published ion levels from a hip resurfacing system presenting the same bearing characteristics, Co levels were significantly higher in LDH-THA (2.2 vs 0.7 ?g/L, P < .001). This study has demonstrated that the addition of a sleeve with modular junctions and an open femoral head design of LDH-THA causes more Co release than bearing surface wear (157% and 67%, respectively). Even if no pathologic metal ion threshold level has been determined, efforts should be made to minimize its release. We recommend modification or abandonment of the modular junction and femoral head open design for this specific LDH-THA system. PMID:20206466

Vendittoli, Pascal-André; Amzica, Traian; Roy, Alain G; Lusignan, Daniel; Girard, Julien; Lavigne, Martin

2011-02-01

331

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

SciTech Connect

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

McCloskey, J.T.; Newman, M.C.; Clark, S.B. [Univ. of Georgia, Aiken, SC (United States). Savannah River Ecology Lab.

1996-10-01

332

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

SciTech Connect

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

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

1999-11-01

333

Studies of Rare-Earth - Transition Metal Permanent Magnet Materials  

NASA Astrophysics Data System (ADS)

Studies of the anomaly in the magnetization of PrCo(,5) near 100K show the cause to be a switch from conical to axial anisotropy with rising temperature. The effects upon the magnetic properties rendered by the partial replacement of Pr in PrCo(,5) by La, Ce, and Nd were investigated. While Ce and La substitutions enhance the anisotropy, they diminish the magnetic moment and the Tc. Nd substitution caused an elevation in Tc and Ms but diminished the anisotropy. Effects of the introduction of small amounts of M = Ti, Zr, and Hf for Pr in Pr(,(1-x))M(,x)Co(,5) were studied; a drop in moment and anisotropy but a surprising elevation in Tc were observed. While Ti and to a lesser extent Hf could partially replace Co in Pr(,2)Co(,(17-x))M(,x), it was found the Zr can only enter the crystal structure by substituting for Pr, as in Pr(,(2-x))Zr(,x)Co(,17). In the Ti- and Hf-doped alloys, spin reorientation effects were observed, but they were not apparent in the Zr-doped alloys. In the Cu-containing alloys with the formula Pr(,2) (Co(,16)Cu)(,(17 -x)/17)M(,x), it was found that Ti, Hf, and Zr could be introduced up to x = 1.0. Substitution by Zr showed the greatest effects upon spin reorientation temperature and anisotropy. Fundamental magnetic properties of the R(,2)Fe(,14)B compounds with R = Y, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Yb and Th were studied. The rare earths nearly reach their free ion moments and the usual R-T coupling systematics are observed in this class of compounds. Permanent magnets based upon PrCo(,5) and upon Pr(,2)Fe(,14)B were fabricated. Respectable energy products were obtained (e.g. 26MGOe and 42MGOe for PrCo(,5) and Pr(,2)Fe(,14)B magnets respectively).

Oswald, Eric Stephen

334

Environmentally relevant metal and transition metal ions enhance Fc epsilon RI-mediated mast cell activation.  

PubMed Central

Upon contact with allergen, sensitized mast cells release highly active proinflammatory mediators. Allergen-mediated mast cell activation is an important mechanism in the pathogenesis of atopic asthma. Asthmatic patients are especially susceptible to air pollution. Epidemiologic studies found a positive correlation between severity of symptoms among asthmatic patients and the level of particulate matter (PM) in the air. Among the constituents of PM are metals and transition metals, which could mediate some of its adverse effects on human health. We sought to determine the effect of metal and transition metal ions on allergen-mediated mast cell activation. We observed that several metal and transition metal ions activated mast cells and enhanced allergen-mediated mast cell activation. Thus, Al(3+), Cd(2+), and Sr(2+) induced release of granule-associated N-acetyl-ss-d-hexosaminidase, and Al(3+) and Ni(2+) enhanced antigen-mediated release. Metal and transition metal ions also induced significant secretion of interleukin (IL)-4 and increased antigen-mediated IL-4 secretion in mast cells. These effects of metal and transition metal ions on mast cells were observed at concentrations that do not result in direct cytotoxicity and might be relevant for environmental exposure. Thus, metals and transition metals could increase the level of allergen-mediated mast cell activation, which might be one of the mechanisms mediating exacerbation of allergen-driven asthma symptoms by air pollution.

Walczak-Drzewiecka, Aurelia; Wyczolkowska, Janina; Dastych, Jaroslaw

2003-01-01

335

Minerals yearbook, 1988. Rare-earth minerals and metals  

SciTech Connect

Domestic production of rare-earth concentrates decreased in 1988. Foreign sources of processed rare earths obtained a slightly larger share of the U.S. market, while domestic exports saw a marked increase compared to 1987 levels. Rare earths were used in high-technology applications such as laser crystals, high-strength permanent magnets, optical fibers, magnetic resonance imaging (MRI) scanners, and high-temperature superconductors. Topics discussed in the report include domestic data coverage, legislation and government programs, environmental issues, domestic production, consumption and uses, stocks, prices, foreign trade, world capacity, world review--Australia, Brazil, Canada, China, Egypt, Greenland, Japan, Madagascar, Malaysia, Mozambique, Sri Lanka, Thailand--and technology.

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

1988-01-01

336

Comet Encke: Meteor Metallic Ion Identification by Mass Spectrometer  

Microsoft Academic Search

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

R. A. Goldberg; A. C. Aikin

1973-01-01

337

Ion Beam Mixing in Metallic Glasses at Low Temperatures.  

National Technical Information Service (NTIS)

Measurements of ion beam mixing of tracer impurities in metallic glasses and in the pure crystalline elements comprising the glasses were performed at approx.80 K. It was observed that the ion mixing efficiency of the tracer impurities was greater in the ...

H. Hahn T. D. de la Rubia R. S. Averback

1987-01-01

338

Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon  

Microsoft Academic Search

Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group

Moonjung Choi; Jyongsik Jang

2008-01-01

339

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

SciTech Connect

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

Bartsch, R.A.

1994-12-31

340

Metal ion deposition from ionized mangetron sputtering discharge  

Microsoft Academic Search

A technique has been developed for highly efficient postionization of sputtered metal atoms from a magnetron cathode. The process is based on conventional magnetron sputtering with the addition of a high density, inductively coupled rf (RFI) plasma in the region between the sputtering cathode and the sample. Metal atoms sputtered from the cathode due to inert gas ion bombardment transit

S. M. Rossnagel; J. Hopwood

1994-01-01

341

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

342

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

343

Effects of Rare Earth Ions on the Quality and the Magnetic Propertes of Ag-FERRITES  

NASA Astrophysics Data System (ADS)

A set of compounds with the formula MgAg0.4R0.2Fe1.4O4 where R is Lanthanum (La3+), Terbium (Tb3+), and Yttrium (Y3+), were prepared by the flash combustion technique. The effect of rare earths ions on some properties of silver doped was investigated. The obtained data indicated that, by introducing a relatively small amount of rare earths ions instead of Fe2O3 ions, an important modification of both the structure and the magnetic properties can be obtained. The Curie temperature, effective magnetic moment and exchange interaction are affected by these substitutions. The effect of rare earth ions were explained both by their partial diffusion in the spinel lattice and by the formation of the crystalline secondary phase on the grain boundaries.

Ahmed, M. A.; Okasha, N.

2011-06-01

344

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

SciTech Connect

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

Lennartsson, O.W.

1994-04-01

345

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

NASA Technical Reports Server (NTRS)

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

Lennartsson, O. W.

1994-01-01

346

Discovery of nitrogen ions in the earth's magnetosphere  

Microsoft Academic Search

Operating in a mass scanning mode, the Retarding Ion Mass Spectrometer (RIMS) has measured N\\/sup +\\/ and N\\/sup + +\\/ ions in the magnetosphere. Both N\\/sup +\\/ and N\\/sup + +\\/ are observed in the plasmapause with N\\/sup +\\/ ions also seen flowing out of the northern polar cap at altitudes up to 3 R\\/sub E\\/. The N\\/sup +\\/ fluxes

C. R. Chappell; R. C. Olsen; J. L. Green; J. F. E. Johnson; J. H. Jr. Waite

1982-01-01

347

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

348

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

PubMed

This Review gives an overview on recent progress in the synthesis and chemistry of rare-earth metal dialkyl complexes bearing monoanionic ancillary ligands, with an emphasis on novel polymerization catalysts. These structurally well-defined and highly reactive compounds are prepared either by alkane elimination reactions between trialkyl rare-earth complexes and acidic neutral ligands, or by the metathetical reactions of rare-earth trihalides with the alkali metal salts of the corresponding ligands. On treatment with an appropriate borate compound, the dialkyl complexes are converted into the corresponding cationic monoalkyl species, which serve as excellent catalysts for the polymerization and copolymerization of a variety of olefins to yield a series of new polymer materials that exhibit novel properties. Alternatively, hydrogenation of the dialkyl rare-earth complexes with H(2) affords a new class of rare-earth polyhydride complexes with unique features in terms of both their structure and reactivity. PMID:21124505

Nishiura, Masayoshi; Hou, Zhaomin

2010-04-01

349

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

NASA Astrophysics Data System (ADS)

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

Nishiura, Masayoshi; Hou, Zhaomin

2010-04-01

350

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

351

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

352

Suppression of Soot in Flames by Alkaline-Earth and Other Metal Additives,  

National Technical Information Service (NTIS)

Experiments were performed to clarify the role of metallic fuel additives in relation to soot suppression in a well defined laboratory-scale diffusion flame. Principal emphasis was given to three alkaline-earth metals; namely, Ba, Sr and Ca. The experimen...

P. A. Bonczyk

1988-01-01

353

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

354

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

355

Reaction of bis(tetraethyl)alanates of alkaline-earth metals with halogens and aluminum halides  

Microsoft Academic Search

1.A study was made of the reaction of the bis(tetraethyl)alanates of the alkaline-earth metals with bromine, iodine, and aluminum halides.2.The metal-carbon bonds in alanate complexes of type M[Al(C2H5)4]2 are more reactive than in triethylaluminum itself.

L. L. Ivanov; S. Ya. Zavizion; L. I. Zakharkin

1974-01-01

356

A specific monovalent metal ion integral to the AA platform of the RNA tetraloop receptor  

Microsoft Academic Search

Metal ions are essential for the folding and activity of large catalytic RNAs. While divalent metal ions have been directly implicated in RNA tertiary structure formation, the role of monovalent ions has been largely unexplored. Here we report the first specific monovalent metal ion binding site within a catalytic RNA. As seen crystallographically, a potassium ion is coordinated immediately below

Soumitra Basu; Robert P. Rambo; Juliane Strauss-Soukup; Jamie H. Cate; Adrian R. Ferré-D´Amaré; Scott A. Strobel; Jennifer A. Doudna

1998-01-01

357

2008 John Charnley Award: Metal Ion Levels After Metal-on-Metal Total Hip Arthroplasty: A Randomized Trial  

Microsoft Academic Search

Metal-on-metal bearing total hip arthroplasty is performed more commonly than in the past. There may be manufacturing differences\\u000a such as clearance, roughness, metallurgy, and head size that affect performance. In a prospective, randomized trial, we compared\\u000a 2-year postoperative ion levels for a 28-mm metal-on-polyethylene bearing with 28-mm and 36-mm metal-on-metal bearings. We\\u000a measured serum, erythrocyte, and urine ion levels. We

C. Anderson Engh Jr; Steven J. MacDonald; Supatra Sritulanondha; Abigail Thompson; Douglas Naudie; Charles A. Engh

2009-01-01

358

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

359

Metallic dental material biocompatibility in osteoblastlike cells: correlation with metal ion release.  

PubMed

Ions released from metallic dental materials used in orthodontic appliances could induce undesirable effects on cells and tissues. This study evaluates the biocompatibility of two of the most labile components of metallic dental alloys on osteoblastlike cells. The influence of protein and ions on metal dissolution properties is also investigated using different electrolyte solutions. Morphological alterations, cell growth, and differentiation of osteoblasts were assessed after exposure to pure metals (Ag, Cu, Pd, Au) and Ni-Ti alloy and correlated with the kinetics of elements released into the culture media. Results showed that Cu and Ag were the most cytotoxic elements and the other metals were biocompatible with the osteoblasts. The parameters of biocompatibility were correlated with the levels of ions detected into the culture media. Metal ions induced cell death through early mitosis arrest, apoptotic phenomena, and necrotic processes. Voltammograms showed that anions and proteins interfered in the corrosion process. Fetal bovine serum (FBS) strongly affected the electrochemical process, decreasing the oxidation rate of the metals. In conclusion, copper and silver ions showed a time-dependent low biocompatibility, which correlated with the concentration of released ions. The dissolution of the metallic materials was dependent on the composition of the simulated biological media. PMID:15326364

Cortizo, María C; De Mele, Mónica Fernández L; Cortizo, Ana M

2004-08-01

360

Comparison of oxygen ion outflow on Earth and Mars during space weather events  

NASA Astrophysics Data System (ADS)

Solar wind controls non-thermal escape of planetary atmospheric volatiles, regardless of the strength of planetary magnetic fields. For both Earth with a strong dipole and Mars with weak remnant fields, the oxygen ion (O+) outflow has been separately found to be enhanced during corotating interaction region (CIR) passage. To discern the role of terrestrial dipole in protecting planetary volatiles, here for the first time, we compared the enhancements of O+ outflow on Earth and Mars to a CIR which passed by in January, 2008 when Sun, Earth and Mars were approximately aligned. The CIR propagation was recorded by STEREO, ACE, Cluster and Mars Express (MEX). During the CIR passage, Cluster observed enhanced flux of upwelling oxygen ions above the Earth's polar region, while MEX detected increased escape flux of oxygen ions in the Martian magnetosphere. We found that, under a solar wind dynamic pressure increase by 2-3 nPa, the rate of increase in Martian O+ outflow flux was one order higher than those on Earth, thus the dipole effectively prevents coupling of solar wind kinetic energy to planetary ions. Surprisingly, as response to the same part of the CIR body, the rate of increase in Martian O+ outflow flux was on the same order as for Earth. We suggest that, besides existence of a dipole field, the distance to the Sun is also crucially important for planetary volatile loss in our inner solar system.

Wei, Y.; Fraenz, M.; Dubinin, E.; Barabash, S.; Dandouras, I. S.; Lundin, R. N.

2012-12-01

361

Solid State Chemistry of Some Polar Intermetallic Tetrelides of the Rare-Earth and Alkaline-Earth Metals  

Microsoft Academic Search

Syntheses of both binary M_5X _3 hosts and M_5X _3Z interstitial compounds with the same Mn_5Si_3 structure type was extended to rare-earth metal tetrelides. The variety of interstitials Z that were incorporated into these host binaries allowed the modulation of the bonding and properties of the host compound without greatly altering or breaking up the structure. Investigations on the binaries

Arnold Mejia Guloy

1992-01-01

362

Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon.  

PubMed

Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group of polypyrrole. The introduced polypyrrole layer could provide the surface modification to be applied for heavy metal ion adsorbents. Especially, polymer-impregnated porous carbon has an enhanced heavy metal ion uptake, which is 20 times higher than that of adsorbents with amine functional groups. Furthermore, the relationship between the coated polymer amount and surface area was also investigated in regard to adsorption capacity. PMID:18602641

Choi, Moonjung; Jang, Jyongsik

2008-09-01

363

Multiply stripped ion generation in the metal vapor vacuum arc  

NASA Astrophysics Data System (ADS)

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. 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.

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

1987-09-01

364

Asymmetric Catalysis with bis(hydroxyphenyl)diamides/rare-earth metal complexes.  

PubMed

A series of asymmetric catalysts composed of conformationally flexible amide-based chiral ligands and rare-earth metals was developed for proton-transfer catalysis. These ligands derived from amino acids provide an intriguing chiral platform for the formation of asymmetric catalysts upon complexation with rare-earth metals. The scope of this arsenal of catalysts was further broadened by the development of heterobimetallic catalytic systems. The cooperative function of hydrogen bonding and metal coordination resulted in intriguing substrate specificity and stereocontrol, and the dynamic nature of the catalysts led to a switch of their function. Herein, we summarize our recent exploration of this class of catalysts. PMID:23180601

Kumagai, Naoya; Shibasaki, Masakatsu

2013-01-01

365

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

366

Fluorescence study of the interaction of Suwannee River fulvic acid with metal ions and Al3+-metal ion competition.  

PubMed

In this study emission and synchronous-scan fluorescence spectroscopy have been used to investigate the interaction of the class A (oxygen seeking 'hard acid') metal Al(3+), with Suwannee River fulvic acid (SRFA), as well as competition between Al(3+) and several other metal ions (Ca(2+), Mg(2+), Cu(2+), Pd(2+), La(3+), Tb(3+) and Fe(3+)) for binding sites on SRFA. Of the four metal ions possessing very similar (and relatively low) ionic indices (Ca(2+), Mg(2+), Cu(2+) and Pd(2+)) only the latter two paramagnetic ions significantly quenched SRFA fluorescence emission intensity. Of the four metal ions possessing very similar (and relatively low) covalent indices (Ca(2+), Mg(2+), La(3+) and Tb(3+)) only the last paramagnetic ion (Tb(3+)) significantly quenched SRFA fluorescence. None of these metals was able to significantly compete with SRFA-bound Al(3+).Fe(3+), which differs substantially from all of the other metals examined in this study in that it possesses a relatively high ionic index (but not as high as Al(3+)) and a relatively low covalent index (but not as low as Al(3+)), was able not only to quench SRFA fluorescence but also to compete (at least to some extent) with SRFA-bound Al(3+). Synchronous-scan fluorescence SRFA spectra taken in the absence and presence of Fe(3+) and/or Al(3+) support the view that these two metal ions can compete for sites on SRFA. The results of these fluorescence experiments further confirm the Al(3+), and metal ions that have electronic properties somewhat similar to Al(3+) (such as Fe(3+)) are somewhat unique in their ability to interact strongly with binding sites on fulvic acids. PMID:15621270

Zhao, Jingyan; Nelson, Donald J

2005-02-01

367

Co-intercalation into graphite of lithium and sodium with an alkaline earth metal  

Microsoft Academic Search

After a short overview on the co-intercalation into graphite of light alkali metals––lithium and sodium––with a third element, novel results concerning the co-intercalation of these alkali metals with an alkaline earth metal are given. The intercalation into graphite of lithium together with magnesium, calcium, strontium and barium is investigated, and the reaction products are described and characterised by X-ray diffraction.

Sébastien Pruvost; Claire Hérold; Albert Hérold; Philippe Lagrange

2004-01-01

368

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

369

Metal ion levels in total hip arthroplasty versus hip resurfacing.  

PubMed

Recent studies suggest that the tapered interface between stem and femoral head may be a substantial source of cobalt and chromium ion release after metal-on-metal (MOM) total hip arthroplasty (THA). This study compared patient ion levels after MOM hip resurfacing (HR) and MOM THA performed with identical acetabular components. 110 HRs were compared with 22 THAs. All had well-oriented components, unilateral implants, and serum ion studies beyond one year post-operatively. The HR group's median cobalt value was 1.11 ?g/L vs. 2.86 ?g/L for the THA patients. The HR group's median chromium value was 1.49 ?g/L vs. 2.94 ?g/L for THA. Significantly higher THA ion levels suggest a source of ions other than the MOM bearing itself. PMID:23618754

Johnson, Alicia J; Le Duff, Michel J; Yoon, James P; Al-Hamad, Mariam; Amstutz, Harlan C

2013-08-01

370

Does ion release differ between hip resurfacing and metal-on-metal THA?  

PubMed

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; Savarino, Lucia; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

2008-03-01

371

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.

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

2008-01-01

372

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

373

Yttrium and rare earth stabilized fast reactor metal fuel  

DOEpatents

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

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

1992-01-01

374

Batch sorption of divalent metal ions onto brown coal  

SciTech Connect

Brown coal, a relatively abundant and inexpensive material is currently being investigated as an adsorbent to remove some contaminants from aqueous solution. The adsorption of some heavy metals from aqueous solutions on the brown coals was studied as a function of pH, contact time, adsorbent dosage and concentration of metal solutions. A carboxyl, phenolic hydroxyl, and metoxyl functional group present on the coal surface was the adsorption site to remove metal ions from solution by means of ion exchange and hydrogen bonding. Effective removal of heavy metals was achieved at pH values of 4.0-5.0. The experimental data have been analyzed using the Langmuir isotherm models. Under optimized conditions, the percentage of metal removal by brown coal adsorption was over 80%.

Pehlivan, E.; Gode, F. [University of Selcuk, Konya (Turkey). Faculty of Engineering & Architecture

2006-12-15

375

Metal ion levels in patients with a lumbar metal-on-metal total disc replacement: should we be concerned?  

PubMed

The purpose of this study was to evaluate whether concerns about the release of metal ions in metal-on-metal total hip replacements (THR) should be extended to patients with metal-bearing total disc replacements (TDR). Cobalt and chromium levels in whole blood and serum were measured in ten patients with a single-level TDR after a mean follow-up of 34.5 months (13 to 61) using inductively-coupled plasma mass spectrometry. These metal ion levels were compared with pre-operative control levels in 81 patients and with metal ion levels 12 months after metal-on-metal THR (n = 21) and resurfacing hip replacement (n = 36). Flexion-extension radiographs were used to verify movement of the TDR. Cobalt levels in whole blood and serum were significantly lower in the TDR group than in either the THR (p = 0.007) or the resurfacing group (p < 0.001). Both chromium levels were also significantly lower after TDR versus hip resurfacing (p < 0.001), whereas compared with THR this difference was only significant for serum levels (p = 0.008). All metal ion levels in the THR and resurfacing groups were significantly higher than in the control group (p < 0.001). In the TDR group only cobalt in whole blood appeared to be significantly higher (p < 0.001). The median range of movement of the TDR was 15.5° (10° to 22°). These results suggest that there is minimal cause for concern about high metal ion concentrations after TDR, as the levels appear to be only moderately elevated. However, spinal surgeons using a metal-on-metal TDR should still be aware of concerns expressed in the hip replacement literature about toxicity from elevated metal ion levels, and inform their patients appropriately. PMID:21705569

Bisseling, P; Zeilstra, D J; Hol, A M; van Susante, J L C

2011-07-01

376

Ion drift in the earth's inner plasmasphere during magnetospheric disturbances and proton temperature dynamics  

NASA Astrophysics Data System (ADS)

Based on the thermal plasma measurements in the Earth’s inner plasmasphere on the INTER-BALL-2 and MAGION-5 satellites it has been indicated that the plasmaspheric ion temperature as a rule decreases during the main phase of magnetic storms; in this case the plasma density increases or remains at the level typical of undisturbed conditions. The physical mechanism by which the ion drift during a magnetic storm results in a temperature decrease is described. It is shown that the third adiabatic invariant also remains in processes with a characteristic time shorter than the period of charged particle drift around the Earth for cold equatorial plasma. The constructed model of the drift shell displacement from the Earth caused by a decrease in the magnetic field in the inner magnetosphere during the development of a magnetic storm satisfactorily describes the decrease in the proton temperature near the equatorial plane.

Verigin, M. I.; Kotova, G. A.; Bezrukikh, V. V.; Bogdanov, V. V.; Kaisin, A. V.

2011-02-01

377

Solar forcing, and ionospheric ion outflow from Venus, Earth and Mars - A comparison  

NASA Astrophysics Data System (ADS)

Solar forcing by e.g. EUV radiation and the solar wind leads to outflow and escape of ionospheric ions from Earth, Venus and Mars. In-situ measurements in the Earth's space environment have demonstrated that the ion escape rate correlates with the magnitude of solar forcing, i.e. high solar EUV and solar wind forcing leads to enhanced escape rates. The Terrestrial outflow is dominated by H+ and O+ suggesting that the ultimate origin of outflowing ions is water. Recent measurements from the two arid planets Mars and Venus, their atmospheres dominated by CO2, display characteristics similar to that of the Earth - an outflow dominated by hydrogen (H+) and oxygen (O+, O2+) ions. Despite major differences in atmospheric composition, the composition of the ion outflow from Earth and Venus is very similar, i.e. H+ and O+ dominates and the outflow has a stoichiometric H/O ratio of close to 2. The latter implies escape of water. The ion outflow from Mars is dominated by O+, O2+, and H+. Here the stoichiometric ratio between hydrogen and oxygen ion is ?1, implying that if the ion outflow originates from water, about half of the hydrogen mass disappears by other means. The primary origin of the ion outflow from Earth, Venus and Mars is a complex issue. Nevertheless, a predominant hydrogen and oxygen loss implies that water can easily escape planets orbiting close to the Sun, while Carbon-based molecules (e.g. CO2) resides more easily. Observations shows that the outflow of e.g. CO+ and CO2+ from Mars and Venus is minute compared to the outflow of hydrogen and oxygen ions. Magnetic shielding is an issue affecting the net ion outflow and escape from a planet, because acceleration processes are also the characteristics of magnetized plasmas. Recent findings suggests that, despite magnetic field pile-up at Mars and Venus, the stand-off distance is insufficient to prohibit a direct interaction between the solar wind and the magnetized ionospheric plasma in the induced magnetospheres of Mars and Venus. On the other hand, a planetary magnetic field, such as the Earth's dipole field and the Martian multipole crustal field, may foster shielding as well as plasma acceleration. However, in this case the ion acceleration may be confined in closed planetary magnetic flux tubes, leading to a low escape rates.

Lundin, R. N.

2012-12-01

378

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

379

Heavy ion irradiation effects in the rare-earth sesquioxide Dy2O3  

Microsoft Academic Search

Polycrystalline pellets of the rare-earth sesquioxide Dy2O3 with cubic C-type rare-earth structure were irradiated with 300 keV Kr2+ ions at fluences up to 5 × 1020 Kr\\/m2 at cryogenic temperature. Irradiation-induced microstructural evolution is characterized using grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). In previous work, we found a phase transformation from a cubic, C-type (Ia3¯) to

M. Tang; P. Lu; J. A. Valdez; K. E. Sickafus

2006-01-01

380

Metal Ion Complexation by Ionizable Crown Ethers.  

National Technical Information Service (NTIS)

Since the last report (Progress Report DOE/ER/10604-4) research has been focused upon the synthesis and characterization of novel ionizable multidentate ligands and their application in competitive solvent extraction of alkali metal cations and alkaline e...

R. A. Bartsch

1985-01-01

381

Process for modifying the metal ion sorption capacity of a medium  

DOEpatents

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

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

2002-01-01

382

Properties of the Rare Earth Metals and Compounds.  

National Technical Information Service (NTIS)

The unclassified literature, both U.S. and foreign, relating to yttrium and the lanthanide rare-earth elements Numbers 57 through 71 has been reviewed to 1964. The best available data on properties have been compiled and are presented in tabular form by p...

G. S. Harvey J. A. Gibson

1966-01-01

383

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

384

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

PubMed Central

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

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

2002-01-01

385

Charge state distribution of anomalous oxygen ions in low Earth orbit during solar quiescence.  

PubMed

A new method of evaluating the charge state distribution of cosmic ray heavy ions, using a measured ratio of particle fluxes observed in two different satellite orbits passing through the Earth's magnetosphere, is described. The measurements of heavy ions were performed simultaneously on the Cosmos 1882 (orbital inclination 82 degrees) and Cosmos 1887 (inclination 62.3 degrees) satellites during September-October 1987. Solid state nuclear track detector stacks were used for the registration of C, N, O and heavier ions. After comparing the data of the two experiments with theoretical calculations, the charge state of galactic and anomalous heavy ions was derived. PMID:11537510

Marenny, A M; Guertzen, G P; Nymmik, R A

1990-01-01

386

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

387

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

388

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

389

Surface Characterization of Alkali and Alkaline Earth Metals on Single Crystal Refractory Metals  

NASA Astrophysics Data System (ADS)

The experiments were conducted on the clean surfaces of W(110), Mo(110) and Nb(110) under ultrahigh vacuum conditions using techniques of line-of-sight thermal desorption mass spectrometry, Auger electron spectroscopy and retarding potential work function measurement. The clean work functions for W(110), Mo(110) and Nb(110) were found to be 5.38 eV, 5.08 eV and 4.62 eV, respectively. The behavior of the work function was characteristic of alkali and alkaline earth metal adsorption onto refractory metal surfaces with the minimum work function for the three surfaces of approximately 1.50 eV for cesium and 2.20 eV for barium. The results of the change in work function versus adsorption of cesium onto the bariated surfaces of W(110), Mo(110) and Nb(110) were similar. The energies of desorption for the different binding states were calculated for the various adsorbate-metal systems using first order desorption kinetics, that is, the adsorbates desorb at a rate linearly dependent on coverage. The desorption spectra for cesium from the various metal surfaces showed three distinct desorption sites, while barium had a more continuous decrease in activation energy of desorption up to a monolayer of coverage. The main difference between the desorption of the two adsorbates was the temperature of the terminal (lowest coverage) desorption energy site. The highest terminal desorption energy for cesium occurred on the W(110) surface at a temperature of 1200 K, while barium does not start to desorb from the W(110) surface until the temperature reaches approximately 1700 K. The temperature difference between the binding states of cesium and barium on all three of the substrates allowed for the adsorption and desorption of cesium without altering the barium adlayer. The desorption behavior of cesium from the various barium/substrate surfaces, like the work function change, was also very similar. As the coverage of pre -adsorbed barium increased, the activation energy of the cesium decreased.

Magera, Gerald Glenn

390

Use of ion characteristics to predict relative toxicity of mono-, di- and trivalent metal ions: Caenorhabditis elegans LC50  

Microsoft Academic Search

Predictive models for relative toxicity of divalent metal ions using ion characteristics have been produced with both Microtox®, a 15 min microbial bioassay, and the 24 h Caenorhabditis elegans bioassay. Relative toxicity of mono-, di- and trivalent metal ions has also been successfully modeled using ion characteristics with the Microtox® bioassay. This study extends this approach to include longer exposure

Christopher P. Tatara; Michael C. Newman; John T. McCloskey; Phillip L. Williams

1998-01-01

391

Surface reactions on rare earth metals monitored by work function measurements  

SciTech Connect

Surface reactions on clean, oxidized, and partially hydrided rare earth metal films with O/sub 2/, H/sub 2/, H/sub 2/O, CO, and CO/sub 2/ were monitored by dynamic work function measurements under ultrahigh vacuum conditions. The work function data are discussed in the light of electron spectroscopic evidence, where available. The main results of this study are: Initial oxidation of Yb seems to follow a different oxidation mechanism as compared to other rare earth metals. Reaction of H/sub 2/O with clean oxidized, and hydrided rare earth metal surfaces yields surface hydroxyl species. H/sub 2/ uptake on divalent Yb metal is much slower than on trivalent Er metal, but occurs at a comparable rate on the oxidized systems. On oxidized surfaces, surface OH formation is substantiated for room-temperature reaction with H/sub 2/. The ..delta.. phi data indicate high reactivity of CO and CO/sub 2/ toward clean rare earth metal surfaces and are consistent with dissociative adsorption of both molecules.

Strasser, G.; Bertel, E.; Netzer, F.P.

1983-02-01

392

Preconcentration and selective metal ion separation using chelating micelles.  

PubMed

Chelating aggregates consisting of Triton X100 host micelles and hydrophobic derivatives of PAN have been examined as suitable candidates for preconcentration and selective separation of transition metal ions through micellar-enhanced ultrafiltration. The effective accumulation in the surfactant-rich retentate of nickel(II), copper(II), cobalt(II), manganese(II) and zinc(II), present at trace levels in aqueous samples, has been achieved by operating at pH ca. 6 with a ligand having a binding constant to the host micelles higher than 2000 l./mol. The efficient separation of micelle-bound metal chelates from unreactive ions has been assessed, together with the feasibility of selective enrichment and purification of the investigated metal ions present in mixtures through a multistage process. PMID:18966066

Pramauro, E; Prevot, A B; Zelano, V; Hinze, W L; Viscardi, G; Savarino, P

1994-08-01

393

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

394

Ion exchange properties of novel hydrous metal oxide materials  

SciTech Connect

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

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

1996-12-31

395

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

PubMed

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

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

2014-01-01

396

Metal ion levels not sufficient as a screening measure for adverse reactions in metal-on-metal hip arthroplasties.  

PubMed

This study aims to assess the accuracy of metal ion analysis in the diagnosis of adverse reaction to metal debris (ARMD) in patients with metal-on-metal hip arthroplasties by comparing the cobalt and chromium levels in 57 patients (62 hips) to findings on metal artifact reduction magnetic resonance imaging (MRI). An ARMD was detected using MRI in 18 (29%) of the hips. Forty patients had cobalt levels less than 7 ?g/L, and 33 had chromium levels less than 7 ?g/L, but 8 of these had an ARMD on MRI and only minimal symptoms (Oxford Hip Score ? 44/48). The incidence of ARMD was significantly higher when chromium concentration was above 7 ?g/L (P = .02), but normal metal ion levels can be misleading and metal artifact reduction MRI imaging is advised in all patients. PMID:22771092

Macnair, Rory D; Wynn-Jones, Henry; Wimhurst, James A; Toms, Andoni; Cahir, John

2013-01-01

397

TRPM7 Provides an Ion Channel Mechanism for Cellular Entry of Trace Metal Ions  

Microsoft Academic Search

Trace metal ions such as Zn 2 ? , Fe 2 ? , Cu 2 ? , Mn 2 ? , and Co 2 ? are required cofactors for many essential cellular enzymes, yet little is known about the mechanisms through which they enter into cells. We have shown previously that the widely expressed ion channel TRPM7 (LTRPC7, ChaK1, TRP-PLIK)

Mahealani K. Monteilh-Zoller; Meredith C. Hermosura; Monica J. S. Nadler; Andrew M. Scharenberg; Reinhold Penner; Andrea Fleig

2002-01-01

398

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

399

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

400

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

PubMed

The chromatographic behavior of 40 metal ions is studied on titanium (IV) arsenate, titanium (IV) phosphate-, titanium (IV) molybdate-, titanium(IV) tungstate-, and titanium(IV) selenite-impregnated papers in 0.1M oxalic, citric, and tartaric acid as mobile phases. Similar studies are carried out on Whatman No. 1 papers for comparison. The ion-exchange capacity of these papers is determined, and their selectivity for different cations is discussed. The mechanism of migration is explained in terms of ion-exchange, precipitation, and adsorption. The prediction of elution sequence from RF values is also checked. The average Ri is found to be almost linearly dependent on the charge of the metal ions. The effect of the pKa of complexing acids on average RF values of 3d series metal ions is explained. A number of binary and ternary separations are achieved. PMID:10677834

Sharma, S D; Gupta, R

2000-02-01

401

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

402

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

403

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

404

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

NASA Technical Reports Server (NTRS)

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

Fuselier, S. A.

1995-01-01

405

Surface metal ion enhancement of thermally treated zeolites  

SciTech Connect

During the past several years the area of zeolite science has received increasingly intense attention owing to the preparation of new molecular sieves and the availability of modern spectroscopic methods for the study of these materials. The majority of spectroscopic studies of zeolites have focused on measurements of bulk magnetic, electronic, and structural properties, but few surface studies have been reported. Surface-inhomogeneous aluminum and silicon species have recently been reported by Barr and co-workers. In this study the authors have heated metal ion containing zeolites under controlled conditions in order to probe interactions between the zeolite and the metal ion. Here they present preliminary results for Ag/sup +//NaY and Cs/sup +//NaY zeolites studied by X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), and ion scattering spectroscopy (ISS).

Willis, W.S.; Suib, S.L.

1986-09-03

406

Are metal ion levels a useful trigger for surgical intervention?  

PubMed

The purpose of this study was to determine if cobalt and chromium ion levels can predict soft tissue damage at total hip revision. This study included 90 metal-on-metal total hip patients with preoperative cobalt and chromium ion levels. Tissue damage noted at revision surgery was graded on a 4-point scale. Sensitivity, specificity, and predictive values were calculated for various threshold values. Receiver operating characteristic analysis was conducted. Using 7 ppb as a threshold, cobalt and chromium ion levels had poor sensitivity and specificity (Co, 65% and 56%; Cr, 29% and 75%). Positive predictive values for cobalt and chromium were only 48% and 26% respectively. The area under the curve was 0.37 for cobalt and 0.44 for chromium. The length of time to revision significantly correlated with tissue damage (P = .001). Ion levels are unreliable predictors of periarticular soft tissue damage and should not be used in isolation as surgical intervention triggers. PMID:22608683

Griffin, William L; Fehring, Thomas K; Kudrna, James C; Schmidt, Robert H; Christie, Michael J; Odum, Susan M; Dennos, Anne C

2012-09-01

407

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

408

Metal plasma immersion ion implantation and deposition: A review  

SciTech Connect

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

Anders, A. [Lawrence Berkeley National Lab., CA (United States). Accelerator and Fusion Research Div.

1996-09-01

409

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

410

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

411

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

412

Development and investigation of a metal ion source for accelerators  

NASA Astrophysics Data System (ADS)

The design and operation of a new spray-type metal ion source are described. The source is built around a plasma emitter containing metal ions and using a two-step glow discharge with double plasma compression. The necessary temperature of electrons in a discharge chamber is reached by distributing the discharge power without heating. The design of the discharge chamber is optimized. The first set of experimental data for the mass-and-charge composition of a beam generated by this source is presented.

Litvinov, P. A.; Baturin, V. A.; Pustovoitov, S. A.

2014-04-01

413

Determination of metal ions in biological purification of waste waters  

SciTech Connect

Chromium, nickel, copper, zinc, and manganese were determined in active sludge extracted for utilization from sewage purification works in biological purification of waste waters. The measurements were carried out by the atomic absorption method and with Merck colorimetric kits for rapid determination of metal ions. The results obtained by the rapid colorimetric method agree fairly well with those obtained by the atomic absorption method, which makes it possible to recommend rapid colorimetric methods for routine analysis of biological objects for the content of ions of heavy metals.

Tikhomirova, L.N.; Spiridonova, N.N.; Mandzhgaladze, I.D. [Moscow State Correspondence Inst. of the Food Industry, Moscow (Russian Federation)] [and others

1994-12-01

414

Formation of gels in the presence of metal ions.  

PubMed

A small library of stereoisomeric pseudopeptides able to make gels in different solvents has been prepared and their attitude to make gels in the presence of several metal ions was evaluated. Four benzyl esters and four carboxylic acids, all containing a moiety of azelaic acid (a long chain dicarboxylic acid) coupled with four different pseudopeptide moieties sharing the same skeleton (a phenyl group one atom apart from the oxazolidin-2-one carboxylic group), were synthesized in solution, by standard coupling reaction. The tendency of these pseudopeptides to form gels was evaluated using the inversion test of 10 mM solutions of pure compounds and of stoichiometric mixtures of pseudopeptides and metal ions. To obtain additional information on the molecular association, the gel samples were left dry in the air to form xerogels that were further analyzed using SEM and XRD. The formation of gel containing Zn(II) or Cu(II) ions gave good results in term of incorporation of the metal ions, while the presence of Cu(I), Al(III) and Mg(II) gave less satisfactory results. This outcome is a first insight in the formation of stable LMWGs formed by stoichiometric mixtures of pseudopeptides and metal ions. Further studies will be carried out to develop similar compounds of pharmacological interest. PMID:21487726

Castellucci, Nicola; Falini, Giuseppe; Angelici, Gaetano; Tomasini, Claudia

2011-08-01

415

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

416

Comet encke: meteor metallic ion identification by mass spectrometer.  

PubMed

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

Goldberg, R A; Aikin, A C

1973-04-20

417

Effect of mechanical surface pretreatment on metal ion release  

Microsoft Academic Search

The degree of metal ion dissolution from Ti–6Al–4V alloy hip replacement stems subjected to various mechanical and chemical surface pretreatments was analysed in vitro. High-dissolution rates were observed for nitric acid passivated samples that had been mechanically surface treated to increase the implant surface area. Significantly lower ion release levels were observed for mechanically treated samples which had been aged

M Browne; P. J Gregson

2000-01-01

418

Extraction of heavy metal ions sorbed on clays  

Microsoft Academic Search

The ability of seventeen different chemical solutions to displace heavy metal ions (Pb, Zn, Cu, Cd), pre-adsorbed on clay (kaolinite, illite and montmorillonite) at either pH 5 or 7, has been examined and the relative efficiency of each extractant ascertained. Of the reagents used, only EDTA (0.001 M, pH 7) quantitatively released all four ions from the three clays; oxalic

Helen Farrah; William F. Pickering

1978-01-01

419

Heavy ion layer in the Earth's stratosphere and its influence on the middle atmosphere processes  

Microsoft Academic Search

Various experimental data prove existence of a layer of charged particles preferably ions of both polarities in the Earth s stratosphere altitudes 15-30 km Data of atmospheric balloon lidar and rocket measurements performed at different latitudes of the both hemispheres during various seasons are considered Results of the mass-spectrometer rocket measurements show that this layer consists mostly of complex ion-clusters

L. N. Makarova; A. V. Shirochkov

2006-01-01

420

Giant optical gain in a rare-earth-ion-doped waveguide amplifier  

Microsoft Academic Search

For optical amplification, typically rare-earth-ion (RE) doped fiber amplifiers (RDFA) or semiconductor optical amplifiers (SOAs) are selected. Despite the weak transition cross-sections of RE ions and their low doping level in silica fibers, resulting in very low gain per unit length, the extremely long interaction lengths realized in fibers can lead to significant overall gain. SOAs can deliver similarly high

D. Geskus; S. Aravazhi; S. M. Garcia Blanco; M. Pollnau

2011-01-01

421

Optical spectra of rare-earth ions in magnesium-aluminum spinel crystals  

Microsoft Academic Search

The authors present the results of their study of optical spectra of rare-earth (RE) ions in magnesium-aluminum spinel crystals. They tabulate data on the composition of charge by content of RE impurities in single crystals, and on transitions in the free ions Tb\\/sup 3 +\\/ and Er\\/sup 3 +\\/ in the lattice of magnesium aluminum spinel. And they present eight

V. T. Gritsyna; V. B. Kol'ner; N. A. Damburg; M. A. Mironova; V. N. Skvortsova

1985-01-01

422

VUV–UV Photoluminescence Spectra of Strontium Orthophosphate Doped with Rare Earth Ions  

Microsoft Academic Search

The measurements of VUV–UV photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra of rare earth ions activated strontium orthophosphate [Sr3(PO4)2:RE, RE = Ce, Sm, Eu, Tb] are performed. Whenever the samples are excited by VUV or UV light, the typical emission of Ce3+, Sm3+, Eu3+, Eu2+ and Tb3+ ions can be observed in PL spectra, respectively. The charge transfer bands

Hongbin Liang; Ye Tao; Qiang Su; Shubin Wang

2002-01-01

423

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

424

In vivo liberation of silver ions from metallic silver surfaces  

Microsoft Academic Search

In vivo liberation of electrically charged silver atoms\\/silver ions from metallic silver pellets, silver grids and silver\\u000a threads placed in the brain, skin and abdominal cavity was proved by way of the histochemical technique autometallography\\u000a (AMG). A bio-film or “dissolution membrane” inserted between the metallic surface and macrophages was recognized on the surface\\u000a of the implanted silver after a short

Gorm Danscher; Linda Jansons Locht

2010-01-01

425

Reactions and Thermochemistry of Small Transition Metal Cluster Ions  

Microsoft Academic Search

This review discusses the reactivities and thermodynamics of small-size-specific transition metal clusters and focuses on thermodynamic information, which has not been comprehensively discussed before. Because of this focus, guided-ion-beam mass spectrometry was used to acquire much of the data. The details of this technique and the associated data analysis methods are provided. Results on the stabilities of bare transition metal

Pb Armentrout

2001-01-01

426

Structure of Some 4f Rare Earth Liquid Metals — A Charged Hard Sphere Approach  

NASA Astrophysics Data System (ADS)

A well-established pseodopotential is used to study the structure of some 4f rare earth liquid metals (Ce, Pr, Eu, Gd, Tb, and Yb). The structure factor S(q), pair distribution function g(r), interatomic distance r1, and coordination number n1 are calculated using Charged Hard Sphere (CHS) reference system. To introduce the exchange and correlation effects, the local field correction due to Sarkar et al. (S) is applied. The present investigation is successful in generating the structural information of Ce, Pr, Eu, Gd, Tb, and Yb 4f rare earth liquid metals.

P. B., Thakor; P. N., Gajjar; A. R., Jani

2006-08-01

427

Energetics of alkaline-earth metal silicides calculated using a first-principle pseudopotential method  

Microsoft Academic Search

The variations of total energies of the following alkaline-earth metal silicides with the cell volumes have been calculated; Mg2Si, Ca2Si, CaSi, CaSi2, Sr2Si, SrSi, SrSi2, BaSi, and BaSi2. The structural change of the alkaline-earth metal disilicides with the promotion to the heavier elements could be relatively well explained though the predicted lattice constants of the equilibrium phases were a bit

Yoji Imai; Akio Watanabe

2002-01-01

428

Valence-shell double photoionization of alkaline-earth-metal atoms  

NASA Astrophysics Data System (ADS)

We apply the convergent close-coupling formalism to describe direct double photoionization (DPI) of the valence ns2 shell of alkaline-earth-metal atoms: beryllium (n=2) , magnesium (n=3) , and calcium (n=4) . We consider the range of photon energies below the onset of resonant and Auger ionization processes where the subvalent and core electrons can be treated as spectators. By comparing alkaline-earth-metal atoms with helium, we elucidate the role of the ground state and final ionized state correlations in DPI of various quasi-two-electron atoms.

Kheifets, A. S.; Bray, Igor

2007-04-01

429

Rates and stoichiometries of metal ion probes of cysteine residues within ion channels.  

PubMed

Metal ion probes are used to assess the accessibility of cysteine side chains in polypeptides lining the conductive pathways of ion channels and thereby determine the conformations of channel states. Despite the widespread use of this approach, the chemistry of metal ion-thiol interactions has not been fully elucidated. Here, we investigate the modification of cysteine residues within a protein pore by the commonly used Ag(+) and Cd(2+) probes at the single-molecule level, and provide rates and stoichiometries that will be useful for the design and interpretation of accessibility experiments. PMID:23870257

Choi, Lai-Sheung; Mach, Tivadar; Bayley, Hagan

2013-07-16

430

Rates and Stoichiometries of Metal Ion Probes of Cysteine Residues within Ion Channels  

PubMed Central

Metal ion probes are used to assess the accessibility of cysteine side chains in polypeptides lining the conductive pathways of ion channels and thereby determine the conformations of channel states. Despite the widespread use of this approach, the chemistry of metal ion-thiol interactions has not been fully elucidated. Here, we investigate the modification of cysteine residues within a protein pore by the commonly used Ag+ and Cd2+ probes at the single-molecule level, and provide rates and stoichiometries that will be useful for the design and interpretation of accessibility experiments.

Choi, Lai-Sheung; Mach, Tivadar; Bayley, Hagan

2013-01-01

431

Smart responsive microcapsules capable of recognizing heavy metal ions.  

PubMed

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

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

2010-09-15

432

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

433

Superconductivity in metal-mixed ion-implanted polymer films  

SciTech Connect

Ion implantation of normally insulating polymers offers an alternative to depositing conjugated organics onto plastic films to make electronic circuits. We used a 50 keV nitrogen ion beam to mix a thin 10 nm Sn/Sb alloy film into the subsurface of polyetheretherketone and report the low temperature properties of this material. We observed metallic behavior, and the onset of superconductivity below 3 K. There are strong indications that the superconductivity does not result from a residual thin film of alloy, but instead from a network of alloy grains coupled via a weakly conducting, ion-beam carbonized polymer matrix.

Micolich, A. P.; Tavenner, E.; Powell, B. J.; Hamilton, A. R.; Curry, M. T.; Giedd, R. E.; Meredith, P. [School of Physics, University of New South Wales, Sydney NSW 2052 (Australia); Physics Department, University of Queensland, Brisbane QLD 4072 (Australia); School of Physics, University of New South Wales, Sydney NSW 2052 (Australia); Center for Applied Science and Engineering, Missouri State University, Springfield, Missouri 65804 (United States); Physics Department, University of Queensland, Brisbane QLD 4072 (Australia)

2006-10-09

434

High Precis ion Interactive Earth Observation with LAPAN -TUBSAT  

NASA Astrophysics Data System (ADS)

Interactive earth observation is a man-in-the loop system where the observer (an astronaut or a space tourist) operates from the spacecraft. In case of LAPAN-TUBSAT the observer operates from the ground instead and only his eye (represented by a video camera) and his movable neck (represented by 3 reaction wheels) fly on board. The installation of a telescope with a magnification factor of 60 against the normal field of view introduces an additional challenge to the high precision attitude control system of the satellite. The 50 kg microsatellite LAPAN-TUBSAT has been jointly built by the Indonesian Space Agency LAPAN and the TU Berlin and was successfully launched in January 2007.

Renner, U.; Buhl, M.

2008-08-01

435

Monitoring of photoluminescence decay by alkali and alkaline earth metal cations using a photoluminescent bolaamphiphile self-assembly as an optical probe.  

PubMed

Photoluminescence (PL) decay induced by the displacement of an ionic fluorescence component, Tb(3+), with alkali and alkaline earth metal cations was investigated using photoluminescent spherical self-assemblies as optical probes. The photoluminescent spherical self-assembly was prepared by the self-organization of a tyrosine-containing bolaamphiphile molecule with a photosensitizer and Tb(3+) ion. The lanthanide ion, Tb(3+), electrically bound to the carboxyl group of the bolaamphiphile molecule, was displaced by alkali and alkaline earth metal cations that had stronger electrophilicity. The PL of the self-assembly decayed remarkably due to the substitution of lanthanide ions with alkali and alkaline earth metal cations. The PL decay showed a positive correlation with cation concentration and was sensitive to the cation valency. Generally, the PL decay was enhanced by the electrophilicity of the cations. However, Ca(2+) showed greater PL decay than Mg(2+) because Ca(2+) could create various complexes with the carboxyl groups of the bolaamphiphile molecule. Microscopic and spectroscopic investigations were conducted to study the photon energy transfer and displacement of Tb(3+) by the cation exchange. This study demonstrated that the PL decay by the displacement of the ionic fluorescent compound was applied to the detection of various cations in aqueous media and is applicable to the development of future optical sensors. PMID:24657611

Kim, Sunhyung; Kwak, Jinyoung; Lee, Sang-Yup

2014-05-01

436

Fluorescence and Energy-Transfer Characteristics of Rare Earth Ions in BaYF5 Crystals.  

National Technical Information Service (NTIS)

Doped fluoride crystals of the type BaLnF5 and BaLn2F8(Ln=LA,...Lu, and Y) are an important class of materials for laser, phosphor, and upconversion applications. These host crystals can be simultaneously doped with divalent and trivalent rare earth ions....

L. Xingren X. Gang R. C. Powell

1986-01-01

437

Determination of rare earth elements by ion chromatography. Separation procedure optimization  

Microsoft Academic Search

In the development of research on materials for optical fibres production, the use of pure lanthanum compounds is very important for the manufacture of glasses, since they can play an important role for signal enhancement by fluorescence emission. For this purpose, an ion exchange chromatographic method for rare earth determination has been studied and optimized. The analytical column involved was

Maria Concetta Bruzzoniti; Edoardo Mentasti; Corrado Sarzanini; Marco Braglia; Giuseppe Cocito; Jörg Kraus

1996-01-01

438

On Atmospheric Loss of Oxygen Ions from Earth Through Magnetospheric Processes  

Microsoft Academic Search

In Earth's environment, the observed polar outflow rate for O+ ions, the main source of oxygen above gravitational escape energy, corresponds to the loss of ~18% of the present-day atmospheric oxygen over 3 billion years. However, part of this apparent loss can actually be returned to the atmosphere. Examining loss rates of four escape routes with high-altitude spacecraft observations, we

K. Seki; R. C. Elphic; M. Hirahara; T. Terasawa; T. Mukai

2001-01-01

439

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

440

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

441

VUV spectroscopy of wide band-gap crystals doped with rare earth ions  

Microsoft Academic Search

Spectral and kinetic properties of vacuum ultraviolet (VUV) luminescence from different fluoride crystals doped with Nd3+, Er3+ or Tm3+ are discussed. Concentration quenching of VUV luminescence, the impact mechanism of the energy transfer from the matrix to the emission centers as well as nonradiative relaxation processes in the rare earth ions have been detected and studied. The crystal properties are

V. N. Makhov; N. M. Khaidukov; N. Yu. Kirikova; M. Kirm; J. C. Krupa; T. V. Ouvarova; G. Zimmerer

2001-01-01

442

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

443

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.

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

1984-01-01

444

Effect of central metal ions on first hyperpolarizability of unsymmetrical metal porphyrins  

NASA Astrophysics Data System (ADS)

We present a quantum-chemical analysis of the central metal ions effect on first hyperpolarizabilities of a series of push-pull porphyrins whose synthesis and NLO properties has been reported earlier [T.G. Zhang, Y. Zhao, I. Asselberghs, A. Persoons, K. Clays, M.J. Therien, J. Am. Chem. Soc. 127 (2005) 9710]. The molecular geometries are obtained via B3LYP/6-31G (d, p) level optimization including SCRF/PCM approach, while the dynamic NLO properties are calculated with the ZINDO/CV method including solvent effects. It has been observed that the first hyperpolarizabilities can be greatly enhanced by changing the central metal ions. It is found that the CT transition between the metal ion's d orbital and the macrocycle ? orbital plays an important role on first hyperpolarizability of metal porphyrins. Our data suggest a new approach to enhance nonlinear optical properties of porphyrin materials.

Bonifassi, P.; Ray, Paresh C.; Leszczynski, J.

2006-11-01

445

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

SciTech Connect

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

Zhao, W. J.; Mueller, M. W. O.; Janik, J.; Liu, K. X.; Ren, X. T. [Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China) and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, 100871 (China); GSI, D64291 Darmstadt (Germany) and Sentastr. 12, D68199, Mannheim (Germany); Institute of Microelectronics, Slovak Technical University, Bratislava, Llcovicova 3 (Slovakia); Institute of Heavy Ion Physics, Peking University, Beijing, 100871 (China) and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, 100871 (China)

2008-02-15

446

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

447

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

PubMed

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

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

2008-02-01

448

Metallic ions in cometary comae and plasma tails  

NASA Astrophysics Data System (ADS)

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