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1

The magnetic hyperfine fields of rare earth ions in metals  

Microsoft Academic Search

Data for the magnetic dipole hyperfine interaction of essentially single rare earth ions in metals, measured with different experimental methods, are collected and discussed. Depending on the host, the magnetic hyperfine field of these paramagnetic ions remains undisturbed by the environment, or it is enlarged, or weakened or can even become completely lost. If there are magnetic ions in the

G. Netz

1986-01-01

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

Doubly charged ions resulting from the multiphoton atomic ionization of alkaline-earth metals  

Microsoft Academic Search

The study of the creation of doubly charged ions upon the laser-induced multiphoton ionization of alkaline-earth metals is\\u000a reviewed. The results show that the features of the creation of the doubly charged ions depend on the spectral range of the\\u000a ionizing laser radiation. In the ionization of the alkaline-earth atoms by the visible laser radiation, the cascade creation\\u000a of the

V. V. Suran; I. I. Bondar

2009-01-01

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

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

SciTech Connect

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

Moeller, Ditte; Soerensen, Jens L.; Thomsen, Jakob B.; Drewsen, Michael [QUANTOP - Danish National Research Foundation Center for Quantum Optics, Department of Physics and Astronomy, University of Aarhus, DK-8000 (Denmark)

2007-12-15

6

Alkaline earth metal ion-exchanged ? zeolite supported Pt catalysts for hydroisomerization of n -heptane  

Microsoft Academic Search

Alkaline earth metal (Mg, Ca, Sr and Ba) ions were exchanged into H? zeolite, which were used as the supports to load the\\u000a noble metal Pt to prepare bifunctional catalysts for hydroisomerization of n-heptane. The catalysts were characterized by ICP, XRD, BET, NH3-TPD, H2-TPR and H2-chemisorption techniques, and evaluated in an atmospheric fixed bed reactor. The catalysts promoted by the

Ping Liu; Xingguang Zhang; Yue Yao; Jun Wang

2010-01-01

7

Coherent spectroscopy of rare-earth-metal-ion-doped whispering-gallery-mode resonators  

NASA Astrophysics Data System (ADS)

We perform an investigation into the properties of Pr3+:Y2SiO5 whispering-gallery-mode resonators as a first step toward achieving the strong coupling regime of cavity QED with rare-earth-metal-ion-doped crystals. Direct measurement of cavity QED parameters are made using photon echoes, giving good agreement with theoretical predictions. By comparing the ions at the surface of the resonator to those in the center, it is determined that the physical process of making the resonator does not negatively affect the properties of the ions. Coupling between the ions and resonator is analyzed through the observation of optical bistability and normal-mode splitting.

McAuslan, D. L.; Korystov, D.; Longdell, J. J.

2011-06-01

8

Selectivity of glassy type mixed zirconium-titanium phosphate toward rare earth metal ions  

Microsoft Academic Search

The selectivity of glass type mixed Zr+Ti phosphates with various Ti contents has been investigated toward rare earth metal ions. The kd values were determined by radiotracer technique both in HCl and HNO3 solutions of various concentrations. At room temperature and at pH=4 the following selectivity orders were found: Yb>TmEu>Sm>La (HCl) and Eu>La>Sm>Yb>Tm (HNO3).

S. K. Shakshooki; A. Dhair; L. Szirtes; Yu. V. Yakovlev

1991-01-01

9

Coherent spectroscopy of rare-earth-metal-ion-doped whispering-gallery-mode resonators  

SciTech Connect

We perform an investigation into the properties of Pr{sup 3+}:Y{sub 2}SiO{sub 5} whispering-gallery-mode resonators as a first step toward achieving the strong coupling regime of cavity QED with rare-earth-metal-ion-doped crystals. Direct measurement of cavity QED parameters are made using photon echoes, giving good agreement with theoretical predictions. By comparing the ions at the surface of the resonator to those in the center, it is determined that the physical process of making the resonator does not negatively affect the properties of the ions. Coupling between the ions and resonator is analyzed through the observation of optical bistability and normal-mode splitting.

McAuslan, D. L.; Korystov, D.; Longdell, J. J. [Jack Dodd Centre for Photonics and Ultra-Cold Atoms, Department of Physics, University of Otago, Dunedin, New Zealand. (New Zealand)

2011-06-15

10

Dansyl - Substituted Aza Crown Ethers: Complexation with Alkali, Alkaline Earth Metal Ions and Ammonium  

PubMed Central

The present study investigates the binding properties of four dansyl substituted aza-crown ethers with alkali, alkaline earth metal ions and ammonium. The influence of the solvent polarity and protonation on the photophysical properties of the compounds was studied by UV/Vis and fluorescence methods. The host species caused only slight changes on the absorption spectra of the ligands. The fluorescence changes were more pronounced and concentration dependent thus allowing to calculate the binding constants of the process. The most stable complex under our working conditions was the one between Ba2+ and DNS18C6.

Deiab, Shihab; Archibong, Edikan; Tasheva, Donka; Mochona, Bereket; Gangapuram, Madhavi; Redda, Kinfe

2011-01-01

11

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

12

AFM studies of DNA structures on mica in the presence of alkaline earth metal ions.  

PubMed

As counterions of DNA on mica, Mg(2+), Ca(2+), Sr(2+) and Ba(2+) were used for clarifying whether DNA molecules equilibrate or are trapped on mica surface. End to end distance and contour lengths were determined from statistical analysis of AFM data. It was revealed that DNA molecules can equilibrate on mica when Mg(2+), Ca(2+) and Sr(2+) are counterions. When Ba(2+) is present, significantly crossovered DNA molecules indicate that it is most difficult for DNA to equilibrate on mica and the trapping degree is different under different preparation conditions. In the presence of ethanol, using AFM we have also observed the dependence of B-A conformational transition on counterion identities. The four alkaline earth metal ions cause the B-A transition in different degrees, in which Sr(2+) induces the greatest structural transition. PMID:12834825

Zheng, Jianping; Li, Zhuang; Wu, Aiguo; Zhou, Hualan

2003-05-01

13

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 (Pr3+) and small amounts of lithium ions (˜0.1-0.2 wt.%) were produced from the tetraethyl orthosilicate (TEOS), AlCl3·6H2O (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 3P0 ? 3H4 (blue) and 3P0 ? 3F3 (red) transitions of Pr3+ 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

14

Alkali metal, alkaline earth metal, and ammonium ion selectivities of dibenzo-16-crown-5 compounds with functional side arms in ion-selective electrodes  

SciTech Connect

Potentiometric selectivities of 11 dibenzo-16-crown-5 compounds for alkali metal, alkaline earth metal, and ammonium ions have been determined in solvent polymeric membrane electrodes. The ionophores bear one or two pendent groups on the central carbon of the three-carbon bridge in the polyether ring. Side-arm variation includes OCH[sub 3], OCH[sub 2]CH[sub 2]OCH[sub 3], OCH[sub 2]CO[sub 2]C[sub 2]H[sub 5], OCH[sub 2]C(O)N(C[sub 2]H[sub 5])[sub 2], and OCH[sub 2]C(O)N(C[sub 5]H[sub 11])[sub 2] units. Attachment of a propyl group to the ring carbon that bears an extended, oxygen-containing side arm increases the selectivity for Na[sup +] relative to larger alkali metal and alkaline earth metal cations. For a given side arm, a linear relationship is obtained when the enhancement in Na[sup +] selectivity produced by attachment of a geminal propyl group is plotted against the diameter of the interference ion. Potentiometric responses of the dibenzo-16-crown-5 compounds are rationalized in terms of the crown ether ring size and the oxygen basicity, conformational positioning, and rigidity of the side arm. 22 refs., 3 figs., 2 tabs.

Ohki, Akira; Lu, J.P.; Huang, X.; Bartsch, R.A. (Texas Tech Univ., Lubbock, TX (United States))

1994-12-01

15

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

16

Reducing decoherence in optical and spin transitions in rare-earth-metal-ion-doped materials  

NASA Astrophysics Data System (ADS)

In many important situations, the dominant dephasing mechanism in cryogenic rare-earth-metal-ion-doped systems is due to magnetic field fluctuations from spins in the host crystal. Operating at a magnetic field where a transition has a zero first-order Zeeman (ZEFOZ) shift can greatly reduce this dephasing. Here we identify the location of transitions with a zero first-order Zeeman shift for optical transitions in Pr3+:YAG and for spin transitions in Er3+:Y2SiO5. The long coherence times that ZEFOZ can enable would make Pr3+:YAG a strong candidate for achieving the strong-coupling regime of cavity QED, and would be an important step forward in creating long-lived telecommunications wavelength quantum memories in Er3+:Y2SiO5. This work relies mostly on published spin-Hamiltonian parameters, but Raman heterodyne spectroscopy was performed on Pr3+:YAG to measure the parameters for the excited state.

McAuslan, D. L.; Bartholomew, J. G.; Sellars, M. J.; Longdell, J. J.

2012-03-01

17

Rare Earth Metals Ion-exchanged ?-Zeolites as Supports of Platinum Catalysts for Hydroisomerization of n-Heptane  

Microsoft Academic Search

A series of Pt catalysts supported on the H?-zeolite that is ion-exchanged with the rare earth metal ions of Ce(III) and La(III), are prepared by impregnation, characterized by inductively coupled plasma (ICP), X-ray diffraction (XRD), BET, temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction of hydrogen (H2-TPR) and H2-chemisorption techniques, and evaluated in the hydroisomerization of n-heptane with an atmospheric fixed-bed

Ping LIU; Yue YAO; Xingguang ZHANG; Jun WANG

2011-01-01

18

Cross-sensitive rare earth metal ion sensors based on extraction systems  

Microsoft Academic Search

A variety of new chemical sensors for determination of triple charged rare earth (RE) metal cations from lanthanum(III) to lutetium(III) (lanthanides) has been developed and studied. Well-known extractants—bidentate neutral organophosphorous compounds, such as methylene diphosphine dioxides and carbamoylmethylphosphine oxides and tetraoctyl-3-oxapentanediamide (TODGA) were used as neutral ligands in the polymeric sensor membranes. It was found that addition of certain substances

A. V. Legin; V. A. Babain; D. O. Kirsanov; O. V. Mednova

2008-01-01

19

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

20

Evidence for resonant magnetic tunneling of rare-earth ions: from insulating to metallic matrix  

Microsoft Academic Search

Tunneling of the total angular momentum of Ho3+ in LiYF4 (insulating matrix) is demonstrated. Due to strong hyperfine interactions, electronic angular momentum and nuclear spin tunnel simultaneously (two-body entanglement) and due to weak dipolar interactions, pairs of Ho3+ ions also tunnel simultaneously (four-body entanglement). Similar results obtained with a metallic matrix (YRu2Si2) prove the persistence of tunneling in the presence

B. Barbara; R. Giraud; W. Wernsdorfer; D. Mailly; P. Lejay; A. Tkachuk; H. Suzuki

2004-01-01

21

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

22

Interaction between metal nitrates and carbohydrates: the topology coordination behavior of galactitol with trivalent lanthanide and divalent alkaline earth ions.  

PubMed

It has long been known that metal ions and saccharides are involved in many biochemical processes. In this paper, metal nitrates were used as reactants to detect the coordination structures of the hydroxyl groups of galactitol in different environments. Three novel crystal structures and FT-IR spectra of metal nitrate-galactitol complexes of La(NO3)3.C6H14O6.(4)H2O, 2Ca(NO3)2.C6H14O6.H2O, and Sr(NO3)2.C6H14O6 were examined in an effort to clarify the structural factors that control metal ion interactions with saccharides in aqueous and biological systems. The coordination structures of galactitol with alkaline earth and lanthanide nitrates in the solid state were compared using FT-IR, Raman, and X-ray diffraction techniques to extensively discuss the coordination rules of different kinds of metal ions. Results provided a model of the coordination sites found in sugars and showed that the introduction of NO3- made the coordination modes of galactitol more diverse and complex than those of the corresponding chloride complexes. Specifically, new coordination modes of galactitol and complicated topology networks were found in 2Ca(NO3)2.C6H14O6.H2O and Sr(NO3)2.C6H14O6. FT-IR results are consistent with the crystal structures and thus provide the possibility of using the similarity of IR spectra to speculate about unknown structures when the compounds are difficult to prepare as single crystals. PMID:17559208

Su, Yunlan; Yang, Limin; Xu, Yizhuang; Wang, Zheming; Weng, Shifu; Yan, Chunhua; Wang, Dujin; Wu, Jinguang

2007-06-09

23

Electric dipole polarizabilities of doubly ionized alkaline-earth-metal ions from perturbed relativistic coupled-cluster theory  

NASA Astrophysics Data System (ADS)

Using perturbed relativistic coupled-cluster (PRCC) theory we compute the ground-state electric dipole polarizability, ?, of doubly ionized alkaline earth metal ions Mg2+, Ca2+, Sr2+, Ba2+, and Ra2+. In the present work we use the Dirac-Coulomb-Breit atomic Hamiltonian and we also include the Uehling potential, which is the leading-order term in the vacuum polarization corrections. We examine the correction to the orbital energies arising from the Uehling potential in the self-consistent field calculations as well as perturbatively. Our results for ? are in very good agreement with the experimental data, and we observe a change in the nature of the orbital energy corrections arising from the vacuum polarization as we go from Mg2+ to Ra2+.

Chattopadhyay, S.; Mani, B. K.; Angom, D.

2013-06-01

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

Self-assembly of anionic porphyrins and alkaline or alkaline earth metal ions mediated by cucurbit[7,8]uril.  

PubMed

Nanoscaled coordination polymers based on biologically prevalent ions have potential applications in drug delivery and biomedical imaging. Herein, coordination polymer nanoparticles of anionic porphyrins, including meso-tetra(4-carboxyphenyl)-porphyrin (H2 TCPP(4-)) and meso-tetra(4-sulfonatophenyl)-porphyrin (H2 TPPS(4-)), and alkaline or alkaline earth metal cations, such as K(+) and Ca(2+), were constructed in aqueous solution in the presence of cucurbit[7]uril (CB7) or cucurbit[8]uril (CB8). UV/Vis absorption and fluorescence spectroscopy, dynamic light scattering (DLS), scanning electron spectroscopy (SEM), and atomic force microscopy (AFM) were applied to explore the assembly and particle formation of porphyrin anions and metal cations mediated by CBn. The particle size depends on the kinds of CBn and metal cations and their concentrations. The uptake of H2 TPPS(4-) particles by tumor cells (A549 cells) was found to be more efficient than H2 TPPS(4-) at 37?°C, showing the application potential of such assembled particles in biology and medicine. PMID:23401023

Lei, Wanhua; Jiang, Guoyu; Zhou, Qianxiong; Hou, Yuanjun; Zhang, Baowen; Cheng, Xuexin; Wang, Xuesong

2013-02-11

26

Application of a silica gel column for the simultaneous determination of alkali and alkaline-earth metal ions with indirect photometric detection using benzyltrimethylammonium chloride as visualization agent  

Microsoft Academic Search

Ion chromatography system for the simultaneous determination of inorganic monovalent and divalent cations was developed using a 50 × 4.6 mm i.d. separation column packed with porous silica gel. The separation was carried out using a mobile phase consisting of benzyltrimethylammonium chloride in aqueous acetonitrile. Alkali and alkaline-earth metal ions were separated within 15 min and indirectly detected at 220

Edison Munaf; Rahmiana Zein; Toyohide Takeuchi; Tomoo Miwa

1997-01-01

27

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

28

Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal  

Microsoft Academic Search

Thermodynamic parameters of complexation of naphto-15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted.

SONG Ming-zhi; ZHU Lan-ying; GAO Xi-ke; DOU Jian-min

29

Reactivation of damaged rare earth luminescence centers in ion-implanted metal–oxide–silicon light emitting devices  

Microsoft Academic Search

Charge trapping and quenching of electroluminescence (EL) in SiO2 layers implanted by Ge and rare earth (RE) ions during hot electron injection were investigated. In case of the SiO2:Ge layer the EL quenching is caused by the transformation of the luminescent defects (Ge–Si or Ge–Ge) to optically inactive centers during hot electron excitation, whereas the EL from rare earth centers

S. Prucnal; L. Rebohle; A. N. Nazarov; I. N. Osiyuk; I. P. Tjagulskii; W. Skorupa

2008-01-01

30

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles  

NASA Astrophysics Data System (ADS)

The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+ -doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

Jia, You-Hua; Zhong, Biao; Yin, Jian-Ping

2009-03-01

31

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

NASA Astrophysics Data System (ADS)

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

Refat, Moamen S.; Mohamed, Soha F.

2011-11-01

32

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

33

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: [M2(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

34

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

35

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

36

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

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

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

39

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

40

Effect of crown ethers on the ion-exchange behavior of alkaline earth metals. Toward improved ion-exchange methods for the separation and preconcentration of radium.  

SciTech Connect

The effect of selected crown ethers on the uptake of alkaline earth cations by sulfonic acid and diphosphonic acid-based cation-exchange resins from hydrochloric acid media is examined. The effect observed is shown to vary with the hydrophobicity of the crown ether. Water-soluble crown ethers enhance the sorption of certain cations, thereby improving the selectivity of the resin for other alkaline earths over calcium ion, an apparent result of a synergistic interaction between crown ether present in the resin phase and the ionic functional groups of the resin. In the presence of more hydrophobic crown ethers, a decrease in cation sorption is often observed, a result of the exclusion of the crown ether from the resin phase and the formation of cation-crown complexes in the solution phase. The result can be a reversal of the selectivity sequence ordinarily exhibited by the resin.

Dietz, M. L.; Chiarizia, R.; Horwitz, E. P.; Bartsch, R. A.; Talanov, V.; Chemistry; Texas Tech Univ.

1997-01-01

41

Simultaneous Determination of Transition and Rare Earth Metal Ions in Nd-Fe-B Material by High Performance Ion Chromatography Using Post-Column Chelation Technique  

Microsoft Academic Search

The transition and lanthanide metal ions of Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in Neodymium-iron-boron (Nd-Fe-B) magnetic material are separated and determined by high performance ion chromatography (HPIC) with spectrophotometric detection using post-column reaction methods. 4-(2-pyridylazo)resorcinol (PAR) and 2-(1,8-dihydroxy-3,6-disulfo-2-naphthylazo)benzenearsonic acid (Arsenazo-III) are used

Rajananda Saraswati

1993-01-01

42

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

43

Enhanced role of electron correlation in the hyperfine interactions in D5/22 states in alkaline-earth-metal ions  

NASA Astrophysics Data System (ADS)

The low-lying n(=3,4,5)d D5/22 states of alkaline-earth-metal ions are of vital importance in a number of different physical applications. The hyperfine structure constants of these states are characterized by unusually strong electron correlation effects. Relativistic coupled-cluster theory has been employed to carry out ab initio calculations of these constants. The role of the all-order core-polarization effects was found to be decisive in obtaining good agreement of our calculated magnetic dipole hyperfine structure constants with accurate measurements. The present work is an apt demonstration of the power of the coupled-cluster method to cope with strongly interacting configurations.

Sahoo, B. K.; Sur, C.; Beier, T.; Das, B. P.; Chaudhuri, R. K.; Mukherjee, D.

2007-04-01

44

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

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

Metal Ions in Unusual Valency States.  

ERIC Educational Resources Information Center

Discusses reactivity of metal ions with the primary products of water radiolysis, hyper-reduced metal ions, zero-valent metal ions, unstable divalent ions from the reduction of bivalent ions, hyper-oxidized metal ions, and metal complexes. (CS)

Sellers, Robin M.

1981-01-01

47

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

48

Rare Earth Metal Silicides and exotic Nuclei  

Microsoft Academic Search

The use of Rare Earth Metal Silicides has been seen in thermal detection since World War II. What results can be expected when Rare Earths are used with certain isotopes? More to the point can exotic isotopes of Rare Earths be made from what is known more recently about Hadrons and their construction? What if anything can be gained from

Richard Kriske

2009-01-01

49

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

50

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

51

Ultraviolet metal ion laser  

SciTech Connect

A metal ion laser is described comprising: a cylindrical vacuum enclosure having a longitudinal axis that is coincident with an unobstructed longitudinal optical axis defined by a resonant optical cavity comprising two mirrors, one at each end thereof, one or both of which mirrors are employed to extract poser from the laser; a cylindrical magnetron sputtering source positioned coaxially with an adjacent to the cylindrical vacuum enclosure; two annular shaped cold cathodes each having diameter substantially equal to the diameter of the cylindrical vacuum enclosure and the two cylindrical anodes; power supply means electrically connected to the metal ion laser for causing the cylindrical magnetron sputtering source to sputter metal vapor from the cylindrical metal cathode tube and for creating rare gas ions.

Collins, G.J.; McNeil, J.R.

1988-03-08

52

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

53

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

54

{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

55

Effect of crown ethers on the ion-exchange behavior of alkaline earth metals. Toward improved ion-exchange methods for the separation and preconcentration of radium  

Microsoft Academic Search

The effect of selected crown ethers on the uptake of alkaline earth cations by sulfonic acid and diphosphonic acid-based cation-exchange resins from hydrochloric acid media is examined. The effect observed is shown to vary with the hydrophobicity of the crown ether. Water-soluble crown ethers enhance the sorption of certain cations, thereby improving the selectivity of the resin for other alkaline

Mark L. Dietz; Renato Chiarizia; E. Philip Horwitz; Richard A. Bartsch; Vladimir Talanov

1997-01-01

56

A discussion on the application and production of metal ion beams  

Microsoft Academic Search

Metal ion beams, which are used in surface modification of metals and alloys as ion beam micrometallurgy, are promising candidates for advanced applications in semiconductors and insulators. Doping with transition metal and rare-earth metal ions in semiconductors and insulators to form metallic nanoclusters attracted much more attention recently, since their applications in diluted magnetic semiconductors, electroluminescent devices, giant magnetic resistance,

Xiaotang Ren; Ziqiang Zhao; Weijiang Zhao

2008-01-01

57

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

58

Determination of transition metal irons based on quenching of the rare earth luminescence  

Microsoft Academic Search

The determination of heavy metal ions was investigated by the use of rare earth ions (Eu3+) as spectroscopic probes. A few heavy metal ions efficiently quenched the luminescence of Eu3+ in polymerized cellulose films which were obtained by sodium carboxymethyl cellulose (Na-CMC) solution and EuCl3 solution or the mixed solution of EuCl3 and a heavy metal chloride. Also, the decay

Tsuyoshi Arakawa; Masami Akamine

2003-01-01

59

Immobilized metal ion affinity chromatography  

Microsoft Academic Search

This article describes the technique of immobilized metal ion affinity chromatography (1MAC). The IMAC stationary phases are\\u000a designed to chelate certain metal ions that have selectivity for specific groups in peptides and on protein surfaces. The\\u000a number of stationary phases that can be synthesized for efficient chclation of metal ions is unlimited, but the critical consideration\\u000a is that there is

Tai-Tung Yip; T. William Hutchens

1994-01-01

60

A statistical study of the upstream intermediate ion boundary in the Earth’s foreshock  

Microsoft Academic Search

A statistical investigation of the location of onset of intermediate and gyrating ion populations in the Earth’s foreshock is presented based on Fixed Voltage Analyzer data from ISEE 1. This study reveals the existence of a spatial boundary for intermediate and gyrating ion populations that coincides with the reported ULF wave boundary. This boundary position in the Earth’s foreshock depends

K. Meziane; C. d’Uston

1998-01-01

61

Bisnitronyl nitroxides bridged by tetra(ethyleneoxy) sensing metal ions spectroscopically and electrochemically  

Microsoft Academic Search

Compound 1 containing two nitronyl nitroxide units bridged by tetra(ethyleneoxy) was designed and synthesized for sensing metal ions, by taking the features of nitronyl nitroxides: a chromophore showing absorption in visible range, reversible oxidation\\/reduction and coordination to metal ions. The absorption spectrum of 1 was altered markedly upon mixing with a few rare earth metal ions and some transition metal

Yanxin Yu; Deqing Zhang; Guanxin Zhang; Zhiyong Wang; Daoben Zhu

2006-01-01

62

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

63

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

64

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

65

Ultrahigh pressure phase transformations in light rare earth metals  

Microsoft Academic Search

The rare earth metals, also known as the lanthanide series, are characterized by the filling of the 4f shell. When pressure is employed as the primary variable, the behavior of rare earth metals becomes very interesting. As pressure increases, the inter-atomic distances decrease substantially because of the high compressibility of rare earth metals. This has significant effects on their structural

Gary Neal Chesnut

2001-01-01

66

Metal ion complexation by ionizable crown ethers  

SciTech Connect

During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The ability of proton- ionizable crown ethers to function as selective metal ion carriers in liquid membrane transport processes has been examined in both bulk liquid membrane and polymer-supported liquid membrane transport systems. New acyclic and cyclic polyether carboxylic acid resins have been prepared by condensation polymerization and characterized.

Bartsch, R.A.

1990-06-01

67

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

68

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

69

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

2013-04-24

70

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

PubMed

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

Ren, Xiaotang; Zhao, Ziqiang; Zhao, Weijiang

2008-02-01

71

A discussion on the application and production of metal ion beams  

NASA Astrophysics Data System (ADS)

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

Ren, Xiaotang; Zhao, Ziqiang; Zhao, Weijiang

2008-02-01

72

A discussion on the application and production of metal ion beams  

SciTech Connect

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

Ren Xiaotang; Zhao Ziqiang; Zhao Weijiang [Institute of Heavy Ion Physics, Peking University, Beijing, 100871 (China) and Key Laboratory of Heavy Ion Physics (Peking University), Ministry of Education, Beijing 100871 (China)

2008-02-15

73

Catalysis using hydrous metal oxide ion exchangers  

DOEpatents

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

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

1983-07-21

74

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

75

Paramagnetic Behavior of Rare-Earth Ions in Some Orthoferrites  

Microsoft Academic Search

Paramagnetic susceptibilities, chii(i{=}a, b, c) of single crystals of rare-earth orthoferrites RFeO3 (R=Nd, Sm, Gd, Dy, Er, Yb and Y) were measured along the a, b and c axes at room temperature and 77 K. The main parts of the effective magnetic moments mueff, i's were found to originate from rare-earth ions. All rare-earth ions except Dy3+ and Er3+ showed

Itsuo Mikami

1973-01-01

76

Miniature high current metal ion source  

SciTech Connect

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

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

1986-04-01

77

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

78

Magnetostriction Due to Rare-Earth Impurities in a Metal  

Microsoft Academic Search

The magnetostriction of dilute alloys of rare-earth impurities in YPd3 follows closely the simple HT dependence of the field-parallel component of a quadrupole moment on the free rare-earth ion moving with the magnetic moment. The saturated magnetostriction per impurity ion is as large as in the magnetically ordered state of rare-earth compounds but does not trace the Stevens factor across

K. Nicholson; U. Häfner; E. Müller-Hartmann; D. Wohlleben

1978-01-01

79

ChemTeacher: Alkaline Earth Metals = Group 2 (IIA)  

NSDL National Science Digital Library

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

2011-01-01

80

Computational Design of Metal Ion Sequestering Agents.  

National Technical Information Service (NTIS)

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 targ...

B. P. Hay B. M. Rapko R. T. Paine K. N. Raymond B. A. Moyer

2004-01-01

81

Rational Design of Metal Ion Sequestering Agents.  

National Technical Information Service (NTIS)

The discriminate bonding of metal ions is a challenge to the synthetic chemist and a phenomenon of considerable practical importance. An important feature of many technical applications is the specific or preferential binding of a single metal ion in the ...

K. N. Raymond

2004-01-01

82

Spectral Analysis for Rare-Earth Ions in Transparent Solids.  

National Technical Information Service (NTIS)

A model was developed that includes a crystal-field Hamiltonian and the free-ion Hamilton ion for the analysis of the spectra of rare-earth ions in transparent solids. The report discusses phenomenological crystal-field parameters, B(km), obtained by the ...

C. A. Morrison D. E. Wortman

1995-01-01

83

Speciation of Metal Ions by Capillary Electrophoresis  

Microsoft Academic Search

The speciation of metal ions by capillary electrophoresis is an important area for environmental chemists. The speciation of metal ions by capillary electrophoresis in different matrices is reviewed. Various aspects of speciation such as sample pretreatment, metal ion complexation, detection, detection limit, choice of electrolytes, etc. have been described. Suggestions to improve the application of CE for the speciation of

Imran Ali; Hassan Y. Aboul-Enein

2002-01-01

84

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

85

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

Microsoft Academic Search

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

S. A. Fuselier; D. A. Gurnett

1984-01-01

86

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

87

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 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...

2009-07-01

88

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

89

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

90

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

Code of Federal Regulations, 2012 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...

2012-07-01

91

Competitive Potentiometric Study of a Series of 18-crown-6 with Some Alkali and Alkaline Earth Metal Ions in Methanol Using an Ag + \\/Ag Electrode  

Microsoft Academic Search

The complexation of some alkali and alkaline earth cations with18-crown-6(18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexyl-18-crown-6 (DCY18C6), and dibenzopyridino-18-crown-6 (DBPY18C6) in a methanol solution has been studied by a competitive potentiometric titration using Ag+\\/Ag electrode as a probe. The stoichiometry and stability constants of the resulting complexes have been evaluated by the MINIQUAD program. The stoichiometry for all resulting complexes was 1:1. The

Javad Zolgharnein; Hoomayon Tahmasebi; Morteza Habibi; Saeid Amani

2004-01-01

92

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

93

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

94

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

Microsoft Academic Search

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

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

2000-01-01

95

IONS OF EXTRATERRESTRIAL ORIGIN IN THE EARTH'S IONOSPHERE  

Microsoft Academic Search

Two of the tasks of the third Russian satellite were to determine the ; chemical composition of the main ion components in the earth's daytime ionosphere ; and to study the variation in composition in the main components with altitude in ; the E, Fâ, and Fâ regions of the ionosphere. In some of the ; measurements, ions were discovered

V ISTOMIN

1963-01-01

96

Magnetic properties of rare earth-transition metal compounds  

Microsoft Academic Search

A survey is given of results obtained by means of rare earth and57Fe Mössbauer spectroscopy on intermetallic compounds of rare earths (R) and 3d metals (M). It is shown how these results can be used to obtain experimental information on crystal field effects, magnetic anisotropy, magnetic moments and magnetic coupling constants. The types of compounds considered in this review comprise

P. C. M. Gubbens; A. M. van der Kraan; K. H. J. Buschow

1990-01-01

97

Engineered Biofilms for Metal Ion Removal  

Microsoft Academic Search

Firstly, biofilm and biosorbents are defined. Mechanisms of interactions between metal ions and biofilm are discussed in terms of diffusion, mass transfer and sorption. In a second step, different processes using biofilm to remove heavy metal in aqueous solutions are presented. The continuously stirred processes are described for metal ion removal in wastewater by biofilm coating particles. In this case,

P. Le Cloirec; Y. Andrè; C. Faur-Brasquet; C. Gérente

2003-01-01

98

Effect of alkaline-earth ions on the dynamics of alkali ions in bismuthate glasses  

NASA Astrophysics Data System (ADS)

The effect of alkaline earth ions on the dynamics of Li+ ions in bismuthate glasses has been studied in the temperature range 353-503K and in the frequency range 10Hz-2MHz . The dc conductivity increases and activation energy decreases with the increase of a particular alkaline earth content for the glasses with a fixed alkali content. The increased modification of the network due to the increase in alkaline earth content in the compositions is responsible for the increasing conductivity. Also the compositions with smaller alkaline earth ions were found to exhibit higher conductivity. Although the conductivity increases with the decrease of ionic radii of alkaline earth ions, the activation energy shows a maximum for the Sr ion. The electric modulus and the conductivity formalisms have been employed to study the relaxation dynamics of charge carriers in these glasses. The alkali ions were observed to change their dynamics with the change of the alkaline earth ions. The same anomalous trend for activation energy for the conductivity relaxation frequency and the hopping frequency was also observed for glasses containing SrO. It was also observed that the mobile lithium ion concentrations are independent of nature of alkaline earth ions in these glasses.

Dutta, A.; Ghosh, A.

2005-12-01

99

Crystallographic phases in heavy rare earth metals under megabar pressures  

NASA Astrophysics Data System (ADS)

Experiments aimed at understanding the crystallographic phases of heavy rare earth metals were carried out in a diamond anvil cell at the Advanced Photon Source, Argonne National Laboratory. Heavy rare earth metals dysprosium (Dy), holmium (Ho), erbium (Er) and thulium (Tm) were compressed to multi-megabar pressures. The rare earth crystal sequence hcp?Sm-type?dhcp?distorted-fcc (dfcc) is observed in all four elements. Upon further compression, a structural transformation to a monoclinic C2/m phase has been observed. We summarize the results from these experiments and present Rietveld structural refinements on high pressure phases for the specific case of dysprosium.

Samudrala, G. K.; Vohra, Y. K.

2012-07-01

100

Magnetic Properties of Rare-Earth Metals and Alloys  

Microsoft Academic Search

A review of neutron diffraction studies of the magnetic properties of rare-earth metals and alloys is presented. For each of the pure metals Tb, Dy, Ho, Er, and Tm there is observed a transition at a temperature TN to an oscillatory antiferromagnetic configuration (helical or linear oscillator type). At lower temperatures, further transitions to ferromagnetic, ferromagnetic spiral, or antiphase domain-type

W. C. Koehler

1965-01-01

101

Multiphonon relaxation of rare-earth ions in oxide glasses  

Microsoft Academic Search

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

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

1977-01-01

102

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

103

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

2013-03-19

104

Alkali earth metal (Ca, Sr, Ba) based thermostable metal-organic frameworks (MOFs) for proton conduction.  

PubMed

Three new alkaline earth metal based MOFs have been synthesized by using 4,4'-sulfobisbenzoic acid (SBBA) and alkaline earth metal salts M(NO(3))(2), M = Ca, Sr, Ba. These MOFs exhibit interesting structural diversity, variable chemical stability as well as proton conductivity. PMID:22509491

Kundu, Tanay; Sahoo, Subash Chandra; Banerjee, Rahul

2012-04-16

105

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

106

MEVVA ion source for high current metal ion implantation  

Microsoft Academic Search

The MEVVA (Metal Vapor Vacuum Arc) ion source is a new kind of source which can produce high current beams of metal ions. Beams of a wide range of elements have been produced, spanning the periodic table from lithium up to and including uranium. The source extraction voltage is up to 60 kV, and we are increasing this up to

I. Brown; J. Washburn

1986-01-01

107

Low specificity of metal ion binding in the metal ion core of a folded RNA  

Microsoft Academic Search

The structure and activity of nucleic acids depend on their interactions with metal ions. Fundamental to these interactions is the degree of specificity observed between the metal ions and nucleic acids, and a complete description of nucleic acid folding requires that we understand the nature of the interactions with metal ions, including specificity. The prior demonstration that high concentrations of

KEVIN J. TRAVERS; NATHAN BOYD; DANIEL HERSCHLAG

2007-01-01

108

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

109

NMR spectroscopy of rare earth–3d transition metal alloys  

Microsoft Academic Search

Recent nuclear magnetic resonance studies of magnetically ordered rare earth–3d transition metal alloys are reviewed. Selected experimental results for rare earth NMR of RETM2 Laves phases as well as RE2TM14B and interstitially modified RE2TM17Ax (A=N,C,H) materials for permanent magnet applications are surveyed. An analysis of the hyperfine parameters obtained from NMR experiments is presented and their relation to the physical

Czes?aw Kapusta

1998-01-01

110

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

111

Separation of metal ions from aqueous solutions  

DOEpatents

This invention is comprised of a process and apparatus for quantitatively and selectively separating metal ions from mixtures thereof in aqueous solution. The apparatus includes, in combination, a horizontal electrochemical flowing cell containing flowing bulk electrolyte solution and an aqueous, metal ion-containing solution, the cell containing a metal mesh working electrode, a counter electrode positioned downstream from the working electrode, an independent variable power supply/potentiostat positioned outside of the flowing cell and connected to the electrodes, and optionally a detector such as a chromatographic detector, positioned outside the flowing cell. This apparatus and its operation has significant application where trace amounts of metal ions are to be separated.

Almon, A.

1991-12-31

112

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

Microsoft Academic Search

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

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

1991-01-01

113

Solar heavy ion Heinrich fluence spectrum at low earth orbit.  

PubMed

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

Croley, D R; Spitale, G C

1998-01-01

114

Uptake of Metal Ions on Humic Acids  

Microsoft Academic Search

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

E. Pehlivan; G. Arslan

2006-01-01

115

Rational Design of Metal Ion Sequestering Agents  

Microsoft Academic Search

The discriminate bonding of metal ions is a challenge to the synthetic chemist and a phenomenon of considerable practical importance.1 An important feature of many technical applications is the specific or preferential binding of a single metal ion in the presence of many metals. Examples range from large-volume uses (e.g. ferric EDTA as a plant food, calcium complexing agents as

Kenneth N

2000-01-01

116

Trace metal and rare earth content of black precipitation events  

SciTech Connect

The authors have used the techniques of non-destructive neutron activation analysis to determine trace metal and rare earth content of black precipitation events occurring in the Cairngorm Mountains in remote areas of Scotland. Thirty-one elements were determined in the particulate matter of snowpack cores that were sliced into sections. An additional analysis was performed for a black acidic snow event. Based on these results and on wind trajectories, increased loadings of many of the heavy metals and rare earth elements appeared to have originated from central Europe. Enrichment factor calculations show anthropogenic emissions for indium, arsenic, zinc, and selenium.

Landsberger, S. (Illinois Univ., Urbana, IL (USA). Dept. of Nuclear Engineering); Davies, T.D. (East Anglia Univ., Norwich (UK). School of Environmental Sciences); Tranter, M. (Dept. of Oceanography, Univ. of Southampton (GB))

1990-01-01

117

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

118

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

119

Estimation of small ion concentration near the Earth's surface  

NASA Astrophysics Data System (ADS)

Atmospheric ions produced by radon gas exhalation from the Earth’s surface can play a vital role in the electrification of atmosphere, especially during nights when the gases are trapped in a stable layer close to the surface. The measurements of concentration of radon and its progeny, air conductivity and aerosol size distribution made at Pune, India, have been analyzed. The concentrations of radon and its progeny show maxima during night and early morning hours, between 0500 and 0700 IST when atmosphere is more stable and mixing is low and start decreasing after sunrise and attain minima during 1000-1800 h when air is unstable. The diurnal variation of the ionization rate, calculated using the concentrations of radon and its progeny, follows the variations of concentrations of radon and its progeny. The ion-aerosol balance equations are solved to study the effect of aerosols on small ion concentration in the lower atmosphere. It has been found that during daytime when aerosol concentration is high, 20-30% reduction in small ion concentration can occur due to aerosols. The small ion concentration estimated using measured air conductivity is compared with small ion concentration estimated by solving ion-aerosol balance equations and both are found to be in good agreement with each other.

Kamsali, Nagaraja; Pawar, S. D.; Murugavel, P.; Gopalakrishnan, V.

2011-10-01

120

High-Performance Chelation Chromatography of Metal Ions on Sorbents with Grafted Iminodiacetic Acid  

Microsoft Academic Search

The chromatographic behavior of some alkaline-earth, transition, heavy, and rare-earth metals on a number of complexing sorbents containing surface iminodiacetic acid (IDA) functional groups is studied. The conditions under which metal retention is determined by complexation on the sorbent surface were established, and the main principles of a new variant of the liquid chromatography, i.e., high-performance chelation ion chromatography (HPCIC),

P. N. Nesterenko; O. A. Shpigun

2002-01-01

121

Metal ion ligands in hyperaccumulating plants  

Microsoft Academic Search

Metal-hyperaccumulating plants have the ability to take up extraordinary quantities of certain metal ions without succumbing\\u000a to toxic effects. Most hyperaccumulators select for particular metals but the mechanisms of selection are not understood at\\u000a the molecular level. While there are many metal-binding biomolecules, this review focuses only on ligands that have been reported\\u000a to play a role in sequestering, transporting

Damien L. Callahan; Alan J. M. Baker; Spas D. Kolev; Anthony G. Wedd

2006-01-01

122

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

123

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

124

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

125

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

126

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

127

Possible ferrimagnetic coupling in light-rare-earth transition-metal intermetallic compounds  

Microsoft Academic Search

The possibility of ferrimagnetic coupling between the magnetic moments of the light-rare-earth (Nd, Pr) ions and of the transition-metal (Fe) ions in Nd6Ga3Fe11- and Pr6Ga3Fe11-based compounds is deduced from the high-field magnetization curves measured at 4.2 K on magnetically aligned and on free-powder samples and from the temperature dependence of the magnetization. The ferrimagnetic coupling is very weak: at 4.2

Z. G. Zhao; F. R. de Boer; V. H. M. Duijn; K. H. J. Buschow; Y. C. Chuang

1994-01-01

128

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

129

Recovery of metal ions by microfungal filters.  

PubMed

Many microfungi contain chitin/chitosan as an integral part of the cell wall structure. The binding of toxic and heavy metal ions by chitosan or partly deacetylated chitin is a direct consequence of the base strength of the primary amine group and is most effective for those metals that form complexes with ammonia. Of the microfungi studied, hyphae from Mucor mucedo and Rhizomucor miehei, after treatment with hydroxide to expose the chitin/chitosan, were found to be most effective in the capture of metal ions. Chemically treated mycelia have so far been shown to bind silver, zinc, lead, copper, nickel, cobalt, cadmium, iron and chromium, with the efficiency of metal-ion binding apparently being inversely proportional to the valency state of the metal ions to be bound. Wet-laid papers produced from mixed slurries of treated mycelia and various conventional paper-making and textile fibres have exceptionally good tensile- and bursting-strength properties, particularly in the wet state. Papers containing 1 g treated mycelia removed up to 90% of various metal ions in solution (50 cm3, 1.5 mmol dm-3) with flow rates of 0.5 cm3 cm-2 min-1. However, the total metal-ion binding capacities of single-thickness microfungal papers are limited under constant flow conditions. The total volume flowing through the system before metal-ion breakthrough occurs increases in direct proportion to the number of sheets of microfungal paper but the concomitant reduction in flow rates becomes a limiting factor. Mycelia-containing structures that allow efficient metal-ion binding at commercially acceptable flow rates are currently being investigated. PMID:1366966

Wales, D S; Sagar, B F

1990-01-01

130

Metal ion complexation by ionizable crown ethers  

SciTech Connect

Since the last informal progress report, research has been focused upon the synthesis and characterization of novel ionizable multidentate ligands and their application in competitive solvent extraction and liquid membrane transport of alkali metal cations and alkaline earth cations. During the report period, considerable attention has been devoted to obtaining a better understanding of the factors which influence the efficiencies and selectivities of alkali metal cation solvent extraction by lipophilic crown ether carboxylic acids.

Bartsch, R.A.

1986-07-15

131

Ion acceleration and transport mechanisms in the Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

This thesis examines the role of ion transport and acceleration in the earth's magnetosphere in two important areas: (1) the entry of solar wind ions in the cusp region on the dayside, and (2) the outflow of ions in the form of ion conics from the pre-midnight aurora. On November 15, 1996, the Polar and FAST satellites were in magnetic conjunction in the cusp region near magnetic local noon. The ion data show that the solar wind plasma injections were bursty in time, but were spatially coherent for 5 hours of magnetic local time. Ion sensors on the two satellites measured particle populations of different energies, but a time-of-flight analysis indicated that Polar and FAST were observing the same bursts of plasma injections from the reconnection region. A convection model was used to estimate the size of the plasma bursts observed. A plasma width of 2412 km was mapped out to the magnetopause to obtain a reconnection injection region latitudinal width of 1.4 to 1.5 RE. On the nightside, the FAST satellite has observed large ion outflow fluxes (>108 cm-2 s-1) in the form of auroral ion conics adjacent to the polar cap boundary. A statistical study was performed to quantify the occurrence of the ion conics in magnetic local time, the relation of the ion conics to substorms, and the total contribution of the ion conics to the plasma sheet. The ion conics occur near magnetic midnight and are associated with substorm expansion phase but not exclusively. Furthermore, using Polar UVI images to estimate the width of the ion conics in local time and FAST ion data to determine the outflow fluxes and latitudinal extent, an estimate of 1022 to 1024 ions/sec is calculated for the outflow. When this outflow is assumed to persist over the duration of a 1000 sec substorm, the total contribution of 1025 to 1027 ions is only 0.01% to 0.1% of the plasma sheet ion number 1030 ions. (Abstract shortened by UMI.)

Tung, Yeh-Kai

132

Shielding and Crystal Fields at Rare-Earth Ions  

Microsoft Academic Search

Several aspects of the crystal field problem of rare-earth ions in ionic solids are discussed. In particular, three problems are considered. (1) A calculation is performed to determine to what extent the 5s2p6 electrons shield the 4f electrons from the crystal field. The shielding is small (<10%) and unimportant compared to the many other uncertainties in crystal field calculations. The

Gerald Burns

1962-01-01

133

Ion probe measurement of rare earth elements in biogenic phosphates  

SciTech Connect

The rare earth element (REE) distributions in individuals 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, P.; Albarede, F. (Ecole Nationale Superieure de Geologie (France))

1989-12-01

134

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

135

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

136

Solvation of isolated transition metal ions.  

National Technical Information Service (NTIS)

X-ray absorption spectroscopy is used to study the structure of transition metal ions as they encounter excess solvent and dissolve; more particularly, Cu in bentonite, with methanol solvent. The distance between the Cu ion and the oxygen atom increases b...

S. R. Wasserman K. A. Carrado

1994-01-01

137

Rare earth-transition metal scrap treatment method  

DOEpatents

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

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

1992-02-11

138

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

139

Adsorption of metal ions on bed sediments  

Microsoft Academic Search

The adsorption of lead and zinc ions on bed sediments of the River Kali in western Uttar Pradesh, India, has been studied. The role of the coarser sediment fraction (210-250 jtm) in controlling metal pollution has been elucidated and compared to those of the clay and silt fractions. The parameters controlling metal uptake, viz., solution pH, sediment dose, contact time,

C. K. JAIN; D. RAM

1998-01-01

140

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

141

Upgraded vacuum arc ion source for metal ion implantation  

SciTech Connect

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

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

2012-02-15

142

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

143

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

144

Solubilities of various alkali metal and alkaline earth metal compounds in methanol  

Microsoft Academic Search

Solubilities of the halides, nitrates, carbonates, sulfates, and some perchlorates of all the alkali metals and alkaline earth metals in methanol at room temperature have been determined. Data on some, such as cesium and rubidium fluoride, nitrate, carbonate, and sulfate, appear to be reported for the first time. Comparison with earlier results from the literature reveals a number of discrepancies.

Vernon A. Stenger

1996-01-01

145

Computational Design of Metal Ion Sequestering Agents  

SciTech Connect

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

Hay, Benjamin P.; Rapko, Brian M.

2005-06-15

146

Computational Design of Metal Ion Sequestering Agents  

SciTech Connect

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

Hay, Benjamin P.; Rapko, Brian M.

2006-06-01

147

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

148

Separation of metal ions in nitrate solution by ultrasonic atomization  

NASA Astrophysics Data System (ADS)

In the ultrasonic atomization of metal nitrate solutions, the molar ratio of metal ions is changed between solution and mist. Small molar metal ions tend to be transferred to mist by ultrasonic wave acceleration, while large molar ions tend to remain in solution. As a result, metal ions can be separated by ultrasonic atomization. We show experimental data and propose a conceptual mechanism for the ultrasonic separation of metal ions.

Sato, Masanori; Ikeno, Masayuki; Fujii, Toshitaka

2004-11-01

149

Separation of metal ions in nitrate solution by ultrasonic atomization.  

PubMed

In the ultrasonic atomization of metal nitrate solutions, the molar ratio of metal ions is changed between solution and mist. Small molar metal ions tend to be transferred to mist by ultrasonic wave acceleration, while large molar ions tend to remain in solution. As a result, metal ions can be separated by ultrasonic atomization. We show experimental data and propose a conceptual mechanism for the ultrasonic separation of metal ions. PMID:15538875

Sato, Masanori; Ikeno, Masayuki; Fujii, Toshitaka

2004-11-15

150

Local magnetism in rare-earth metals encapsulated in fullerenes  

Microsoft Academic Search

Local magnetic properties of rare-earth (RE) atoms encapsulated in fullerenes have been characterized using x-ray magnetic circular dichroism and x-ray absorption spectroscopy (XAS). The orbital and spin contributions of the magnetic moment have been determined through sum rules and theoretical model calculations, and have been found to be highly reduced compared to those of the corresponding free RE3+ ions. Crystal-field

C. de Nadaï; A. Mirone; S. S. Dhesi; P. Bencok; N. B. Brookes; I. Marenne; P. Rudolf; N. Tagmatarchis; H. Shinohara; T. J. S. Dennis

2004-01-01

151

Oxidation by hydrogen in the chemistry and physics of the rare-earth metals.  

PubMed

Rare-earth metals (RE) easily react with hydrogen. For decades the bonding of hydrogen has been discussed controversially in terms of either the "proton model" or the "anion model". Detailed investigations of metal-rich compounds of the rare-earth metals provide clear evidence for the incorporation of hydrogen as a hydride anion. Several categories of compounds can be distinguished regarding their behavior towards hydrogen. Low-valence compounds with metal-metal bonding frequently provide their excess electrons to form hydride ions as found with the halide hydrides REXH(n). However, there are exceptions, such as, LaI which does not react with hydrogen as a result of special electronic and electrostatic conditions. The opposite is true with La(2)C(3) although this compound does not provide excess metal valence electrons. An amorphous phase La(2)C(3)H(1.5) forms at very low temperature, around 450 K. The presence of hydrogen strongly influences the electrical and magnetic properties, for example, spin-glass formation and colossal magneto resistance arising in the presence of 4f(n) cores with the lanthanoid elements. PMID:22431365

Simon, Arndt

2012-03-16

152

Rare Earth metal-mediated group transfer polymerization of vinylphosphonates.  

PubMed

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

Salzinger, Stephan; Rieger, Bernhard

2012-07-10

153

MEVVA ion source for high current metal ion implantation  

SciTech Connect

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

Brown, I.; Washburn, J.

1986-07-01

154

Chapter 237 Rare Earth–Transition Metal–Plumbides  

Microsoft Academic Search

The chapter on rare earth–transition metal–plumbides reviews the phase relationships, the crystal chemistry and the physical properties of the RxTyPbz plumbides. The basic crystallographic data of all known RxTyPbz plumbides are listed and the structure types occurring for the plumbides are discussed in detail with respect to crystal chemical relations and chemical bonding. The property part covers the magnetic and

Rainer Pöttgen; Ute Ch. Rodewald

2007-01-01

155

Growth of oriented rare-earth-transition-metal thin films  

SciTech Connect

Rare-earth-transition-metal thin films are successfully grown by magnetron sputtering onto single-crystal MgO substrates with epitaxial W buffer layers. The use of epitaxial W buffer layers allows oriented single-phase films to be grown. Sm-Co films grown onto W(100), have strong in-plane anisotropy and coercivities exceeding 5 T at 5 K whereas Fe-Sm films have strong perpendicular anisotropy and are magnetically soft.

Fullerton, E.E.; Sowers, C.H.; Bader, S.D. [Argonne National Lab., IL (United States); Wu, X.Z. [Argonne National Lab., IL (United States)]|[Northern Illinois Univ., DeKalb, IL (United States)

1996-04-01

156

Computational Design of Metal Ion Sequestering Agents  

SciTech Connect

Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort. This project seeks to enhance and strengthen the traditional approach through computer-aided design of new and improved host molecules. Accurate electronic structure calculations are coupled with experimental data to provide fundamental information about ligand structure and the nature of metal-donor group interactions (design criteria). This fundamental information then is used in a molecular mechanics model (MM) that helps us rapidly screen proposed ligand architectures and select the best members from a set of potential candidates. By using combinatorial methods, molecule building software has been developed that generates large numbers of candidate architectures for a given set of donor groups. The specific goals of this project are: • further understand the structural and energetic aspects of individual donor group- metal ion interactions and incorporate this information within the MM framework • further develop and evaluate approaches for correlating ligand structure with reactivity toward metal ions, in other words, screening capability • use molecule structure building software to generate large numbers of candidate ligand architectures for given sets of donor groups • screen candidates and identify ligand architectures that will exhibit enhanced metal ion recognition. These new capabilities are being applied to ligand systems identified under other DOEsponsored projects where studies have suggested that modifying existing architectures will lead to dramatic enhancements in metal ion binding affinity and selectivity. With this in mind, we are collaborating with Professors R. T. Paine (University of New Mexico), K. N. Raymond (University of California, Berkeley), and J. E. Hutchison (University of Oregon), and Dr. B. A. Moyer (Oak Ridge National Laboratory) to obtain experimental validation of the predicted new ligand structures. Successful completion of this study will yield molecular-level insight into the role that ligand architecture plays in controlling metal ion complexation and will provide a computational approach to ligand design.

Hay, Benjamin P.; Rapko, Brian M.

2005-06-15

157

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

Microsoft Academic Search

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

James B Hedrick

1997-01-01

158

Metal ions affecting the skin and eyes.  

PubMed

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

Lansdown, Alan B G

2011-01-01

159

Rare-Earth nanoparticles with enhanced upconversion emission and suppressed rare-Earth-ion leakage.  

PubMed

Upconversion emissions from rare-earth nanoparticles have attracted much interest as potential biolabels, for which small particle size and high emission intensity are both desired. Herein we report a facile way to achieve NaYF(4):Yb,Er@CaF(2) nanoparticles (NPs) with a small size (10-13 nm) and highly enhanced (ca. 300 times) upconversion emission compared with the pristine NPs. The CaF(2) shell protects the rare-earth ions from leaking, when the nanoparticles are exposed to buffer solution, and ensures biological safety for the potential bioprobe applications. With the upconversion emission from NaYF(4):Yb,Er@CaF(2) NPs, HeLa cells were imaged with low background interference. PMID:22488939

Wang, Ye-Fu; Sun, Ling-Dong; Xiao, Jia-Wen; Feng, Wei; Zhou, Jia-Cai; Shen, Jie; Yan, Chun-Hua

2012-04-04

160

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

161

Novel metal ion surface modification technique  

SciTech Connect

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

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

1990-10-01

162

Comparative study of ion cyclotron waves at Mars, Venus and Earth  

Microsoft Academic Search

Ion cyclotron waves are generated in the solar wind when it picks up freshly ionized planetary exospheric ions. These waves grow from the free energy of the highly anisotropic distribution of fresh pickup ions, and are observed in the spacecraft frame with left-handed polarization and a wave frequency near the ion’s gyrofrequency. At Mars and Venus and in the Earth’s

H. Y. Wei; C.T. Russell; T. L. Zhang; X. Blanco-Cano

2011-01-01

163

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)

1996-11-01

164

Operational characteristics of a metal vapor vacuum arc ion source  

Microsoft Academic Search

The MEVVA ion source can produce high current pulsed beams of metallic ions using a metal vapor vacuum arc discharge as the plasma medium from which the ions are extracted. In this study, the operational characteristics of the MEVVA IV ion sources are summarized. Results are presented of measurements of the ion beam current as a function of arc current

Hiroshi Shiraishi; Ian G. Brown

1990-01-01

165

Alkaline and alkaline earth metal phosphate halides and phosphors  

SciTech Connect

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

166

Metallic rare-earth silicide nanowires on silicon surfaces.  

PubMed

The formation, atomic structure, and electronic properties of self-assembled rare-earth silicide nanowires on silicon surfaces were studied by scanning tunneling microscopy and angle-resolved photoelectron spectroscopy. Metallic dysprosium and erbium silicide nanowires were observed on both the Si(001) and Si(557) surfaces. It was found that they consist of hexagonal rare-earth disilicides for both surface orientations. On Si(001), the nanowires are characterized by a one-dimensional band structure, while the electronic dispersion is two-dimensional for the nanowires formed on Si(557). This behavior is explained by the different orientations of the hexagonal c axis of the silicide leading to different conditions for the carrier confinement. By considering this carrier confinement it is demonstrated how the one-dimensional band structure of the nanowires on Si(001) can be derived from the two-dimensional one of the silicide monolayer on Si(111). PMID:23221358

Dähne, Mario; Wanke, Martina

2012-12-05

167

Ion implantation makes metals last longer  

SciTech Connect

Ion implantation is an atomic level surface treatment that modifies the structure of a metal's near-surface region, producing a new alloy without altering part dimensions. The process is most often used to enhance wear resistance, but sometimes is chosen to improve corrosion resistance. Surfaces subject to adhesive and abrasive wear last anywhere from two to 100 times longer after they have been ion implanted. In the process, ions of the element or elements to be implanted are accelerated toward the target surface. When the beam strikes the surface, the ions become embedded in it to a depth of up to 1[mu]m, producing a new alloy in the implanted region. The concentration-verses-depth profile of implanted ions is controlled by the amount of element used, its mass, and the accelerating voltage.

Holtkamp, B. (Implant Sciences Corp., Wakefield, MA (United States))

1993-12-01

168

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

169

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

PubMed

The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions. The vibrational FT-IR (in KBr and ATR techniques) and (1)H and (13)C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg?Ba were compared with series of univalent metal Li?Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds. PMID:21862395

Samsonowicz, M; Regulska, E; Lewandowski, W

2011-08-03

170

Arc discharge ion source for europium and other refractory metals implantation  

NASA Astrophysics Data System (ADS)

The best method for the impurity doping to the host material is the ion implantation. Due to high melting point of the rare earth standard metal ion sources are useless. One of the solution is to use chemical compounds of rare earths characterized by low melting point. In this paper we describe the novel design of the ion source suitable for refractory metal (e.g., rare earths) ion implantation. The dependencies of Eu+ current on cathode and arc currents as well as on hydrogen flow are presented. Europium (III) chloride as the source of the europium atoms was used. Europium ions were produced during collisions of evaporated and decomposed EuCl3 molecules with fast electrons. The typical current of the europium ion beam extracted from the ion source was 25 ?A for the extraction voltage of 25 kV. The ion source works without maintenance breaks for approximately 50 h, which enables high dose implantation. The presented ion source needs neither advanced high power supplies nor high vacuum regime.

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

2009-04-01

171

IMMUNOASSAYS FOR METAL IONS. (R824029)  

EPA Science Inventory

Abstract Antibodies that recognize chelated forms of metal ions have been used to construct immunoassays for Cd(II), Hg(II), Pb(II), and Ni(II). In this paper, the format of these immunoassays is described and the binding properties of three monoclonal antibodies direc...

172

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

173

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

174

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

175

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

176

Metal Ion Measurement: One Surgeon's 30 Year Perspective  

Center for Biologics Evaluation and Research (CBER)

Text VersionSerum Co & Cr Levels Metal Ion Measurement: One Surgeon's 30 Year ... Page 3. Is Measurement of Metal Ions Appropriate and/or Clinically Useful ? ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

177

Quadrupole Antishielding Factors for Rare-Earth and Some Other Heavy Ions.  

National Technical Information Service (NTIS)

Sternheimer quadrupole antishielding factors are reported for several rare-earth ions and for several ions isoelectronic with I(-) and Br(-). Radial excitations were obtained using the selfconsistent-field unrestricted Hartree-Fock method described previo...

R. E. Watson A. J. Freeman

1964-01-01

178

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

179

Substrate Profile and Metal-ion Selectivity of Human Divalent Metal-ion Transporter-1*  

PubMed Central

Divalent metal-ion transporter-1 (DMT1) is a H+-coupled metal-ion transporter that plays essential roles in iron homeostasis. DMT1 exhibits reactivity (based on evoked currents) with a broad range of metal ions; however, direct measurement of transport is lacking for many of its potential substrates. We performed a comprehensive substrate-profile analysis for human DMT1 expressed in RNA-injected Xenopus oocytes by using radiotracer assays and the continuous measurement of transport by fluorescence with the metal-sensitive PhenGreen SK fluorophore. We provide validation for the use of PhenGreen SK fluorescence quenching as a reporter of cellular metal-ion uptake. We determined metal-ion selectivity under fixed conditions using the voltage clamp. Radiotracer and continuous measurement of transport by fluorescence assays revealed that DMT1 mediates the transport of several metal ions that were ranked in selectivity by using the ratio Imax/K0.5 (determined from evoked currents at ?70 mV): Cd2+ > Fe2+ > Co2+, Mn2+ ? Zn2+, Ni2+, VO2+. DMT1 expression did not stimulate the transport of Cr2+, Cr3+, Cu+, Cu2+, Fe3+, Ga3+, Hg2+, or VO+. 55Fe2+ transport was competitively inhibited by Co2+ and Mn2+. Zn2+ only weakly inhibited 55Fe2+ transport. Our data reveal that DMT1 selects Fe2+ over its other physiological substrates and provides a basis for predicting the contribution of DMT1 to intestinal, nasal, and pulmonary absorption of metal ions and their cellular uptake in other tissues. Whereas DMT1 is a likely route of entry for the toxic heavy metal cadmium, and may serve the metabolism of cobalt, manganese, and vanadium, we predict that DMT1 should contribute little if at all to the absorption or uptake of zinc. The conclusion in previous reports that copper is a substrate of DMT1 is not supported.

Illing, Anthony C.; Shawki, Ali; Cunningham, Christopher L.; Mackenzie, Bryan

2012-01-01

180

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

181

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

182

Vibrational study of ionic association in polar aprotic solvents. Isocyanate complexes of non-transition-metal ions  

Microsoft Academic Search

Complexes between alkaline-earth-metal ions M2+ and cyanate OCN? in aprotic solvents are studied by infrared spectrometry in the ?(CN) region (2150–2250 cm?1). In dimethylsulphoxide (DMSO) and hexamethylphosphotriamide (HMPT) isocyanate MNCO ion pairs exhibit a specific ?(CN) band while M(NCO)2 species usually have two ?(CN) bands. Pure alkaline earth cyanates are in part dissociated into MNCO+ and OCN? in DMSO. When

Corinne Le Borgne; Martial Chabanel

1997-01-01

183

Tungstate-ferrates of some alkali and alkaline-earth metals  

SciTech Connect

Tungstate-ferrates of some alkali and alkaline-earth metals with the ratio Fe:W = 2:11, the iron ions in which are found in two types of coordination, tetrahedral and octahedral, were synthesized. The similarity of the IR spectra of the compounds obtained and known compounds with the anion structure of the Keggin type with the composition M/sub X/(XZW/sub 11/O/sub 40/H/sub m/) x nH/sub 2/O indicates that their heteropolyanions are isostructural. The thermal stability of the compounds studied and the structure of the products of thermolysis depend on the charge and radius of the extrasphere cation. When the ratio of the radii of the extrasphere cation of the alkali or alkaline-earth metal to the radius of the ion of the central 3d element, appearing in the coordination sphere of the heteropolytungstates, exceeds 1.6, the most likely products of thermolysis of heteropolycompounds are the compounds of the pyrochlore family and tungsten bronzes.

Gruba, A.I.; Danileiko, L.A.; Moroz, Ya.A.; Zyats, M.N.

1988-02-01

184

Characteristics of the Ion Pressure Tensor in the Earth's Magnetosheath  

NASA Astrophysics Data System (ADS)

Active Magnetospheric Particle Tracer Explorer/Isothermal Remanent Magnetization (AMPTE/IRM) satellite data are used to examine characteristics of the ion pressure tensor in the earth's magnetosheath. The eigenvalues and principal axes of the pressure tensor are computed, and the directions of the principal axes are compared to the direction of the independently measured magnetic fiedl B. When the pressure tensor is anisotropic, as is usually the case in the magnetosheath, on of its eigenvalues is observed to be distinguishable from the other two, which are about equal to one another. Thus, the eigenvector associated with the distinguishable eigenvalue defines an axis of symmetry of the pressure tensor. The symmetry axis is generally not parallel to B. New features of the plasma distribution function are revealed by using the actual eigenvalues of the pressure tensor rather than the usual symbols to denote directions perpendicular and parallel to B.

Li, Xinlin; Lewis, H. R.; Labelle, J.; Phan, T.-D.; Treumann, R. A.

1995-03-01

185

Chelation ion chromatography of trace metal ions using metallochromic ligands  

Microsoft Academic Search

Hydrophobic metallochromic ligands can be used to coat high-performance reversed-phase substrates producing chelating stationary phases with the capacity to separate metal ions. To date the main approaches have been to `pre-coat' the substrate with the ligand and use it with a mobile phase containing an inorganic salt or alternatively to include the ligand itself within the mobile phase, where the

Paul R Haddad

1999-01-01

186

Investigation of MEVVA ion source for metal ion injection into accelerators at GSI  

Microsoft Academic Search

High current metal ion production is a challenging task for ion source designers. The MEVVA ion source has proven to be a useful tool for accelerator injection and for ion implantation. We have investigated the MEVVA ion source in connection with the GSI heavy ion accelerators. At the Unilac accelerator as injector for the heavy ion Synchrotron SIS (1 Hz

B. H. Wolf; H. Emig

1994-01-01

187

A statistical study of the upstream intermediate ion boundary in the Earth's foreshock  

Microsoft Academic Search

A statistical investigation of the location of onset of intermediate and gyrating ion populations in the Earth's foreshock is presented based on Fixed Voltage Analyzer data from ISEE 1. This study reveals the existence of a spatial boundary for intermediate and gyrating ion populations that coincides with the report- ed ULF wave boundary. This boundary position in the Earth's foreshock

K. Meziane; C. d'Uston

1998-01-01

188

A Theoretical Model of Energy Transfer between Rare Earth Ions in Crystals  

Microsoft Academic Search

The limitation of the random walk theory of energy transfer between rare earth ions in crystals published in literatures is pointed out in this paper. A modified model, which can be used in any level of rare earth ion concentration when the interaction between donor and acceptor is different from that between donors, is introduced. This model has been applied

LIN Yan-Fu; LUO Zun-Du

189

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

190

Metal ion complexation by ionizable crown ethers  

SciTech Connect

Research conducted since the last progress report includes the synthesis and characterization of twenty three novel proton-ionizable crown ether compounds. Metal ion complexation behavior of new and previously-synthesized proton-ionizable crown ether compounds has been probed by solvent extraction and transport across polymer-supported liquid membranes. The behavior of neutral polyether and proton-ionizable polyether ligands in polymeric membrane electrodes has been assessed. Studies of the use of proton-ionizable crown ethers for separation of lithium isotopes were initiated. Also, the thermodynamics of interactions between alkali metal cations and ionized crown ethers have been probed by titration calorimetry. 10 refs., 1 tab.

Bartsch, R.A.

1989-09-01

191

Comparative study of ion cyclotron waves at Mars, Venus and Earth  

Microsoft Academic Search

Ion cyclotron waves are generated in the solar wind when it picks up freshly ionized planetary exospheric ions. These waves grow from the free energy of the highly anisotropic distribution of fresh pickup ions, and are observed in the spacecraft frame with left-handed polarization and a wave frequency near the ion's gyrofrequency. At Mars and Venus and in the Earth's

H. Y. Wei; C. T. Russell; T. L. Zhang; X. Blanco-Cano

2011-01-01

192

Metal-ion spin-on glasses: Novel materials for active waveguides  

SciTech Connect

Monolithic integration of a rare-earth-ion-based active waveguide on the same wafer as its diode pump laser would permit compact packaging of the technology demonstrated in fiber lasers and amplifiers. This new monolithic technology would offer the potential for developing compact infrared and visible (up-conversion) lasers, amplifiers, and other photonic integrated circuit components. One approach that we are investigating for such monolithic integration uses a high concentration of one or more rare-earth ions incorporated into polysiloxane spin-on glasses that are solvent-cast onto III-V semiconductor wafers. This ``fiber on a chip`` technology substitute a relatively high-ion-concentration, short-length metal-ion spin-on glass (MISOG) waveguide for the low-ion-concentration, long-length fiber. Progress to data on developing MISOG waveguide materials and technology is discussed.

Ashby, C.I.H.; Sullivan, C.T.; Vawter, G.A.; Hohimer, J.P.; Hadley, G.R.; Neal, D.R.

1993-12-31

193

IDENTIFICATION OF CATALYTIC METAL ION LIGANDS IN RIBOZYMES  

PubMed Central

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

Frederiksen, John K.; Piccirilli, Joseph A.

2012-01-01

194

Cross-sensitive rare-earth metal sensors based on bidentate neutral organophosphorus compounds and chlorinated cobalt dicarbollide  

Microsoft Academic Search

A variety of new chemical sensors (ion selective electrodes) for determination of rare-earth (RE) and trivalent metal cations such as yttrium(III), lanthanum(III), praseodymium(III), neodymium(III) and europium(III) that are commonly present in aqueous radiological samples, e.g. in high-level liquid waste (HLW) and solutions from reprocessing spent nuclear fuel, have been developed and studied. The sensors are based on bidentate neutral organophosphorus

A. V. Legin; D. O. Kirsanov; V. A. Babain; A. V. Borovoy; R. S. Herbst

2006-01-01

195

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

196

Arc discharges in alkali-earth metal vapors as possible pump sources for YAG:Nd\\/3+\\/ lasers  

Microsoft Academic Search

The spectral energy distribution in the region from 500 to 920 nm of radiation from sapphire arc lamps with vapors of the alkali-earth metals K, K+Rb, and Na+K has been measured. It is shown that for a specific choice of vapor pressure the radiation efficiency of these lamps in the absorption bands of the Nd ions in YAG:Nd(3+) crystals is

A. Iu. Ananev; S. F. Davydov; I. V. Kolpakova; A. A. Mak; S. A. Iakovlev

1979-01-01

197

Electrochemical luminescence of n-type ZnO semiconductor electrodes doped with rare earth metals under the anodic polarization  

Microsoft Academic Search

Electrochemical luminescence (ECL) at n-type ZnO semiconductor electrode was measured under anodic polarization. Scanning the potential imposed on the ZnO electrode, emission was suddenly observed around +20V. Using the ZnO electrodes doped with rare earth metal ions as Sm3+, Eu3+, Dy3+, Ho3+ and Er3+, much brighter emission was obtained than the ECL of non-doped ZnO. These emission spectra are ascribed

Toshihito Ohtake; Satoshi Hijii; Noriyuki Sonoyama; Tadayoshi Sakata

2006-01-01

198

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

2013-06-04

199

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.

2013-06-01

200

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

201

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

202

Oxidation-reduction reactions of metal ions.  

PubMed Central

Several metal or metalloid ions exist in multiple oxidation states and can undergo electron transfer reactions that are important in biological and environmental systems. There are endogenous metal ions such as iron, copper, and cobalt that participate in oxidation-reduction reactions with species of oxygen like molecular dioxygen, superoxide, and hydrogen peroxide. These reactions may be modulated by endogenous reducing agents such as glutathione, ascorbate, and tocopherol. The reactions can be described in terms of thermodynamics through the use of standard electrode potentials. A favorable reaction will depend on the concentrations of the reactants and may depend on the pH and/or on the presence of organic ligands that form complexes with the metal or metalloid. Arsenate (As(V)) can react with glutathione in buffered aqueous solutions to produce arsenite (As(III)) and oxidized glutathione. This reaction may be important in the methylation reactions of arsenic. Arsenic species can decrease the red blood cell levels of reduced glutathione, but the products of oxidation and the mechanism of oxidation are more complex than those found in water alone. Chromium (VI) is thought to interact with DNA after first reacting with a reducing agent such as glutathione to form lower oxidation states of chromium. These examples illustrate the importance of oxidation-reduction reactions for toxic metals and metalloids.

Carter, D E

1995-01-01

203

Analysis of metallic pigments by ion microbeam  

NASA Astrophysics Data System (ADS)

Metallic paints consist of metallic flakes dispersed in a resinous binder, i.e. a light-element polymer matrix. The spatial distribution and orientation of metallic flakes inside the matrix determines the covering efficiency of the paint, glossiness, and its angular-dependent properties such as lightness flop or color flop (two-tone). Such coatings are extensively used for a functional (i.e. security) as well as decorative purpose. The ion microbeam analysis of two types of silver paint with imbedded metallic flakes has been performed to determine the spatial distribution of the aluminum flakes in paint layer. The average sizes of the aluminum flakes were 23 /?m (size distribution 10-37) and 49 /?m (size distribution 34-75), respectively. The proton beam with the size of /2×2 /?m2 at Ljubljana ion microprobe has been used to scan the surface of the pigments. PIXE mapping of AlK/? map shows lateral distribution of the aluminum flakes, whereas the RBS slicing method reveals tomograms of the flakes in uppermost 7 /?m of the pigment layer. The series of point analysis aligned over the single flake reveal the flake angle in respect to the polymer matrix surface. The angular sensitivity is well below 1 angular degree.

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

2002-05-01

204

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

205

The free-powder magnetization of ferrimagnetic rare-earth transition-metal compounds  

Microsoft Academic Search

Magnetization curves have been calculated for single crystals of ferrimagnetic rare-earth transition-metal compounds that are free to rotate in the applied magnetic field. The calculations have been performed taking into account the magnetic-anisotropy constants of the rare-earth and transition-metal sublattices up to the fourth order. Seven different types of rotation processes can be distinguished.

Z. G. Zhao; F. R. de Boer; K. H. J. Buschow

1993-01-01

206

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

207

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

208

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

209

Rational Design of Metal Ion Sequestering Agents  

SciTech Connect

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

Raymond, Kenneth N.

2000-09-30

210

Ion species measurement of high current metal ion beams extracted from a multicusp ion source  

Microsoft Academic Search

Ion charge state and impurities extracted from a multicusp ion source have been studied with the use of a magnetic momentum mass analyzer. Impurities contained in high current metal ion beams are crucible materials (such as Al2O3, BN, Y2O3, C) and high melting point materials (such as Mo, Ta, W). To reduce these impurities, the dependence of the impurity on

Yasuhiro Matsuda; Hiroshi Inami; Takatoshi Yamashita; Shuichi Fujiwara; Yutaka Inouchi; Kouzi Matsunaga; Koji Matsuda

1992-01-01

211

[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

212

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

213

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

214

Towards liquid metal ion source chips: Indium liquid metal ion source with glass microcapillaries  

NASA Astrophysics Data System (ADS)

A liquid-metal-ion-source with indium propellant using an uncoated fused quartz glass microcapillary was manufactured and tested. The extremely thin capillary enabled a very low ignition voltage of 1000 V and a high electrical impedance ideal for clustering. However, low bonding forces between indium and glass resulted in a rather short lifetime of little more than 10 min. The use of pure glass as emitter material may enable liquid ion source chips with high current densities in the future.

Tajmar, M.; Plesescu, F.

2013-01-01

215

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

216

Substrate profile and metal-ion selectivity of human divalent metal-ion transporter-1.  

PubMed

Divalent metal-ion transporter-1 (DMT1) is a H(+)-coupled metal-ion transporter that plays essential roles in iron homeostasis. DMT1 exhibits reactivity (based on evoked currents) with a broad range of metal ions; however, direct measurement of transport is lacking for many of its potential substrates. We performed a comprehensive substrate-profile analysis for human DMT1 expressed in RNA-injected Xenopus oocytes by using radiotracer assays and the continuous measurement of transport by fluorescence with the metal-sensitive PhenGreen SK fluorophore. We provide validation for the use of PhenGreen SK fluorescence quenching as a reporter of cellular metal-ion uptake. We determined metal-ion selectivity under fixed conditions using the voltage clamp. Radiotracer and continuous measurement of transport by fluorescence assays revealed that DMT1 mediates the transport of several metal ions that were ranked in selectivity by using the ratio I(max)/K(0.5) (determined from evoked currents at -70 mV): Cd(2+) > Fe(2+) > Co(2+), Mn(2+) ? Zn(2+), Ni(2+), VO(2+). DMT1 expression did not stimulate the transport of Cr(2+), Cr(3+), Cu(+), Cu(2+), Fe(3+), Ga(3+), Hg(2+), or VO(+). (55)Fe(2+) transport was competitively inhibited by Co(2+) and Mn(2+). Zn(2+) only weakly inhibited (55)Fe(2+) transport. Our data reveal that DMT1 selects Fe(2+) over its other physiological substrates and provides a basis for predicting the contribution of DMT1 to intestinal, nasal, and pulmonary absorption of metal ions and their cellular uptake in other tissues. Whereas DMT1 is a likely route of entry for the toxic heavy metal cadmium, and may serve the metabolism of cobalt, manganese, and vanadium, we predict that DMT1 should contribute little if at all to the absorption or uptake of zinc. The conclusion in previous reports that copper is a substrate of DMT1 is not supported. PMID:22736759

Illing, Anthony C; Shawki, Ali; Cunningham, Christopher L; Mackenzie, Bryan

2012-06-26

217

[Studies on rare earth ions complexation properties of tetranitrophenols-armed Aza-18-crown-6].  

PubMed

The synthesis of macrocyclic ligands appended with fluorescent or chromogenic chelators is a promising approach to developing metal--ion chemosensors because of the ion selectivity of macrocyclic ligands and the fluorescence or chromogenic response of the appended chelating groups. In the present paper, 1,10-dioxa-4,7,13,16-tetraaza-18-crown-6(L1) and 4,7,13,16-tetra(2-hydroxy-5-nitrobenzyl)-1, 10-dioxa-4,7,13,16-tetraaza-18-crown-6(L2) were synthesized and characterized via elemental analysis and 1H NMR spectrum. The complexation properties of L2 for H+, Ce3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, DY3+ and Yb3+ were studies by UV-Vis method in H2 -DMSO (earth ions were added to the solution, the absorption peak of L2 above 400 nm was shifted toward short wavelength, and absorption intensity was increased obviously in comparison with L2 alone. Thus the formation of the complex was verified, and it was formed at pH>7.0. The stability constants of the complexes obtained show that stability of the complexes depends upon the match between cavity dimension of L2 and size of the rare earth ions. There was a decrease in stability of complex with decreasing the radius of rare earth ion in the order of Ce3 +>Nd3+ >Sm3+ >Eu"3+>Gd3+ >Tb3+ >Dy3+ >Yb3+. PMID:19248510

Zhang, Qiang; Gao, Sheng-hua

2008-12-01

218

Preparation of poly (aryl ether ketones) in the presence of an alkali, alkaline earth of lanthanide metal salt  

SciTech Connect

This patent describes a process for preparing poly(aryl ether ketones) by nucleophilic displacement polymerization in the presence of at least one alkali metal base selected from potassium, rubidium or cesium, and fluoride ions, which comprises adding to the polymerization: (a) an effective amount of at least one metal salt selected from lithium, sodium, alkaline earth or lanthanide chloride, bromide, iodide, sulfate, alkyl or aryl carboxylate, cyanide, borate or phosphate to slow or stop advancement of molecular weight and (b) an end-capping agent.

Kelsey, D.R.

1988-09-27

219

Multiheteromacrocycles that complex metal ions. Sixth progress report, 1 May 1979-30 April 1980. [Hemispherands; spherands  

SciTech Connect

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

Cram, D.J.

1980-01-15

220

Ion beam superpolishing of metal mirrors for high energy lasers  

Microsoft Academic Search

A new process has been developed which employs a low energy ion beam to superpolish metal surfaces. The process is applicable in principle to all metals. This technique overcomes the tendency of metal surfaces to develop etch patterns and other surface irregularities during ion beam bombardment. The process produces superpolished optical surfaces significantly superior to those formed by conventional optical

J. D. Lester; H. Gelles; R. T. Cook

1975-01-01

221

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

PubMed

Six new alkaline-earth metal carboxyphosphonates [Mg(H2O)(H2PMIDA)] (), [Sr(H2O)(H2PMIDA)] (), [Sr2(H2O)(PMIDA)] (), [Sr2(HPO4)(H2PMIDA)] (), [Ba2(HPO4)(H2PMIDA)] (), and [Ba2(H2O)(H2PMIDA)2] () (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 , , and are three-dimensional with the H2PMIDA skeletons connecting the inorganic parts to each other, whereas compound has a layered structure. Compounds , and contain helical structural motifs. In addition, the extrinsic luminescent properties of Eu(iii)- and Tb(iii)-doped compounds , and 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

2013-10-15

222

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

223

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

224

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

PubMed

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

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

2012-04-26

225

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

226

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

227

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

2006-05-19

228

SEPARATION OF PLUTONYL IONS  

DOEpatents

A process is described for separating plutonyl ions from the acetate ions with which they are associated in certaln carrier precipitation methods of concentrating plutonium. The method consists in adding alkaline earth metal ions and subsequently alkalizing the solution, causing formation of an alkaltne earth plutonate precipitate. Barium hydroxide is used in a preferred embodiment since it provides alkaline earth metal ion and alkalizes the solution in one step forming insoluble barium platonate.

Connick, R.E.; McVey, Wm.H.

1958-07-15

229

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

2013-04-19

230

Coordination polymer networks with s-block metal ions  

Microsoft Academic Search

Alkali and alkaline earth metal cations form the s-block elements of the periodic table where they belong to the groups 1 and 2, respectively. They play an important role in nature, for instance alkali cations Li+, Na+ and K+ have very specific functions such as the regulation of the ionic equilibrium of living cells in our body. Alkaline earth cations

Katharina M. Fromm

2008-01-01

231

Determination of metal ions using ion chromatography and indirect amperometric detection  

SciTech Connect

A method for determination of metal ions subsequent to ion chromatographic separation has been devised. The method is based on indirect amperometric detection whereby a decrease in an oxidation current, proportional to the concentration of metal ion, is monitored. In this particular work, an easily oxidized ligand is added postcolumn. Upon complexation with the metal ions, the ligand is rendered electroinactive at the preselected potential. The fact that the ligand is oxidized at low anodic potentials results in a selective detection system.

Hojabri, H.; Lavin, A.G.; Wallace, G.G.; Riviello, J.M.

1987-01-01

232

Colorimetric method for determining Pb2+ ions in water enhanced with non-precious-metal nanoparticles.  

PubMed

Sulfur anions and their derivatives have long been recognized for their high selectivity and reactivity toward Pb(2+) ions and formation of highly absorptive yet water-insoluble compounds with both acid and base media. This phenomenon has been used for qualitative analysis of lead ions in water. We demonstrate a new method to quantitatively determine the Pb(2+) concentration in the range of 0.5-500 ppm in water using colorimetric measurement, based on forming "soluble" lead sulfide in water enhanced with non-precious-metal nanoparticles. This method has inherent high selectivity for lead over other alkali-metal and alkaline-earth-metal ions. The colorimetric measurements of the absorptive solutions provide accurate determination of the lead concentration in water comparable to that measured using inductively coupled plasma mass spectrometry. To our knowledge, this is the simplest, lowest cost, and easiest-to-use method for detecting and determining the lead concentration in water. PMID:22686469

Yan, Jeffrey; Indra, Erik M

2012-06-25

233

Calmodulin inhibition: a possible predictor of metal-ion toxicity  

SciTech Connect

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

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

1986-01-01

234

Ternary rare earth and actinoid transition metal carbides viewed as carbometalates  

Microsoft Academic Search

Ternary carbides AxTyCz (A=rare earth metals and actinoids; T=transition metals) with monoatomic species C4? as structural entities are classified according to the criteria (i) metal to carbon ratio, (ii) coordination number of the transition metal by carbon atoms, and (iii) the dimensionality of the anionic network [TyCz]n?. Two groups are clearly distinguishable, depending on the metal to carbon ratio. Those

Enkhtsetseg Dashjav; Guido Kreiner; Walter Schnelle; Frank R. Wagner; Ruediger Kniep; Wolfgang Jeitschko

2007-01-01

235

Near equality of ion phase space densities at earth, Jupiter, and Saturn  

Microsoft Academic Search

Energetic-ion phase-space density profiles are strikingly similar in the inner magnetospheres of earth, Jupiter, and Saturn for ions of first adiabatic invariant near 100 MeV\\/G and small mirror latitudes. Losses occur inside L approximately equal to 7 for Jupiter and Saturn and inside L approximately equal to 5 at earth. At these L values there exist steep plasma-density gradients at

A. F. Cheng; S. M. Krimigis; T. P. Armstrong

1985-01-01

236

Daily intakes of alkaline earth metals in Japanese males  

SciTech Connect

Diet samples were collected for two duplicate portion studies and one market basket study. {sup 226}Ra in the diet samples was determined by alpha spectrometry and daily intake was estimated as 23 mBq (0.62 pCi) per person. Other alkaline earth metals were determined by inductively coupled plasma atomic-emission spectrometry. Average mineral intakes of calcium, magnesium, strontium, and barium were 0.55 g, 0.21 g, 2.3 mg, and 0.39 mg, respectively. Element ratios magnesium:calcium 0.38, strontium:calcium 4.2 x 10{sup -3} barium:calcium 7.1 X 10{sup -4}, and Ra:calcium 1.1 x 10{sup -12} were found in the diet; these compared with element ratios in Japanese vertebrae of magnesium:calcium 0.011, strontium:calcium 3.1 x 10{sup -4}, barium:calcium 2.7 x 10{sup -5}, and radium:calcium 2.6 x 10{sup -14}. Observed ratios, defined as the element ratio in bone divided by the respective element intake ratio in Japanese males, were as follows: {sup 226}Ra 0.02, magnesium 0.03, strontium 0.07, and barium 0.04.

Shiraishi, Kunio [National Institute of Radiological Sciences, Ibaraki (Japan); Yamamoto, Masayoshi; Ueno, Kaoru [Kanazawa Univ., Ishikawa (Japan)] [and others

1994-01-01

237

When VSEPR fails: experimental and theoretical investigations of the behavior of alkaline-earth-metal acetylides.  

PubMed

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. PMID:19844925

Guino-o, Marites A; Alexander, Jacob S; McKee, Michael L; Hope, Håkon; Englich, Ulrich B; Ruhlandt-Senge, Karin

2009-11-01

238

Enthalpies of dissolution of elements in liquid tin: II. Transition, alkali and alkaline-earth metals  

Microsoft Academic Search

In the framework of a general compilation devoted to the enthalpies of dissolution of elements in liquid tin, the data concerning the partial enthalpies at infinite dilution of transition metals, alkali metals and alkaline–earth metals in tin have been collected from literature and selected data are given. When the number of data was large enough, they were fitted against temperature

Abeer Yassin; Robert Castanet

2001-01-01

239

Mechanism of the modification of steel by alkaline-earth metals  

Microsoft Academic Search

Group IIa alkaline-earth metals (AEMs) of the periodic table are widely used in metallurgy for modifying steels and cast irons, which results in the variation of the properties of metals and nonmetallic inclusions improving the service properties of metal products [1]. However, the mechanism of AEM modification of steels is not clearly understood to date. The causes of the change

A. A. Deryabin; E. Yu. Berestov

2008-01-01

240

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

241

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

242

Conformational thermodynamics of metal-ion binding to a protein  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

243

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

244

METAL ION COORDINATION STUDIES ON A SILICA-BASED ION EXCHANGE RESIN BEFORE AND AFTER HEATING  

Microsoft Academic Search

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

James V. Beitz; Clayton W. Williams

2001-01-01

245

Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements.  

National Technical Information Service (NTIS)

Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method ...

J. E. Selle

1992-01-01

246

Minerals yearbook, 1989: Rare-earth minerals and metals  

SciTech Connect

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

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

1989-01-01

247

Calmodulin Inhibition: A Possible Predictor of Metal-Ion Toxicity.  

National Technical Information Service (NTIS)

A correlation between CE sub 50 , the metal-ion concentration which reduces the cloning efficiency of CHO cells by 50%, and IC sub 50 , the metal-ion concentration that produces an inhibition of calmodulin activity of 50%, is reported for 10 divalent meta...

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

1986-01-01

248

Electron Capture Dissociation of Trivalent Metal Ion-Peptide Complexes  

NASA Astrophysics Data System (ADS)

With electrospray ionization from aqueous solutions, trivalent metal ions readily adduct to small peptides resulting in formation of predominantly (peptide + MT - H)2+, where MT = La, Tm, Lu, Sm, Ho, Yb, Pm, Tb, or Eu, for peptides with molecular weights below ~1000 Da, and predominantly (peptide + MT)3+ for larger peptides. ECD of (peptide + MT - H)2+ results in extensive fragmentation from which nearly complete sequence information can be obtained, even for peptides for which only singly protonated ions are formed in the absence of the metal ions. ECD of these doubly charged complexes containing MT results in significantly higher electron capture efficiency and sequence coverage than peptide-divalent metal ion complexes that have the same net charge. Formation of salt-bridge structures in which the metal ion coordinates to a carboxylate group are favored even for (peptide + MT)3+. ECD of these latter complexes for large peptides results in electron capture by the protonation site located remotely from the metal ion and predominantly c/ z fragments for all metals, except Eu3+, which undergoes a one electron reduction and only loss of small neutral molecules and b/ y fragments are formed. These results indicate that solvation of the metal ion in these complexes is extensive, which results in the electrochemical properties of these metal ions being similar in both the peptide environment and in bulk water.

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

2013-02-01

249

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

250

Ion implantation enhanced metal-Si-metal photodetectors  

SciTech Connect

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

Sharma, A.K.; Scott, K.A.M.; Brueck, S.R.J. (Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials); Zolper, J.C.; Myers, D.R. (Sandia National Labs., Albuquerque, NM (United States))

1994-05-01

251

Progress and experience on testing methods of metal-enclosed earthing switches.  

National Technical Information Service (NTIS)

Current switching operation tests, reproducing stresses in line with actual service stresses, were performed on metal-enclosed earthing switches of different make and for system voltages ranging from 145 to 420 kV. The tested earthing switches were single...

A. Bargigia G. Aldrovandi E. Emolumento

1989-01-01

252

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

253

Spectroscopic detection of metals ions using a novel selective sensor  

NASA Astrophysics Data System (ADS)

Colorimetric chemosensors are simple, economical and practical optical approach for detecting toxic metal ions (Hg2+, Pb2+, Ni2+, etc.) in the environment. In this work, we present a simple but highly specific organic compound 4-chloro-2-((E)-((E)-3-(4-(dimethylamino)phenyl)allylidene)amino)phenol (L1) that acts as a colorimetric sensor for divalent metal ions in H2O. The mechanism of the interaction between L1 and various metal-ions has been established by UV-vis absorption and emission spectroscopic experiments that indicate favorable coordination of metal ions with L1 in different solvents. Experimental results indicate that the shape of the electronic transition band of L1 (receptor compound) changed after the interaction with divalent metal-ions, such as Hg2+, Pb2+, Mn2+, Co2+, Cu2+, and Ni2+ in aqueous solution. We found that L1 have a considerable selectivity for Ni2+ ions, even in presence of other metals ions when mixtures of DMSO/H2O as are used as solvents. L1, which has been targeted for sensing transition metal ions, exhibits binding-induced color changes from yellow to pink observed even by the naked eye in presence of Ni2+ ions.

Peralta-Domínguez, D.; Ramos-Ortiz, G.; Maldonado, J. L.; Rodriguez, M.; Meneses-Nava, M. A.; Barbosa-Garcia, O.; Santillan, R.; Farfan, N.

2011-08-01

254

Metal ion complexes of EDTA as solutes for density gradient ultracentrifugation: influence of metal ions.  

PubMed

In the study reported here, we study the nature of the metal ion complexes of EDTA as solute systems for analysis of lipoproteins by density gradient ultracentrifugation (DGU) by varying both the complexing metal ion and the counterion. Specifically, the sodium and cesium salts of complexes of Bi/EDTA, Pb/EDTA, Cd/EDTA, Fe/EDTA, and Cu/EDTA were chosen for this study. We show that useful gradients can be formed within a few hours beginning with a homogeneous solution. Data are presented that provide insight into the nature of how these gradients are formed from these complexes and how the selection of a specific complex can be used to enhance particular regions of the lipoprotein density profile for clinical studies. We also examine the use of equilibrium sedimentation theory to correlate the measured density profiles generated by these complexes with their molecular weight. PMID:16255609

Johnson, Jeffery D; Bell, Natalie J; Donahoe, Erin L; Macfarlane, Ronald D

2005-11-01

255

Observational evidence on the origin of ions upstream of the earth's bow shock  

Microsoft Academic Search

The energies predicted by four different source hypotheses for ions observed upstream of the earth's bow shock are compared with observations of upstream field-aligned beams and gyrating ion events. A kinematic formalism in a frame of reference in which the motional electric field vanishes is used. Specular reflection of a fraction of the incident solar wind is found to be

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

1983-01-01

256

Observational evidence on the origin of ions upstream of the earth's bow shock  

Microsoft Academic Search

The kinematic formalism described by Schwartz et al. (1983) is used to quantitatively compare the zeroth order predicted energies for four different source hypotheses for ions detected upstream of the earth's bow shock with previously published observations of upstream field-aligned beams and gyrating ion events. Specular reflection of a fraction of the incident solar wind is found to be the

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

1983-01-01

257

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

258

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

259

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

260

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

261

Dehydration of fructose to 5-hydroxymethylfurfural by rare earth metal trifluoromethanesulfonates in organic solvents  

Microsoft Academic Search

The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) was investigated by using various rare earth metal trifluoromethanesulfonates, that is, Yb(OTf)3, Sc(OTf)3, Ho(OTf)3, Sm(OTf)3, Nd(OTf)3 as catalysts in DMSO. It is found that the catalytic activity increases with decreasing ionic radius of rare earth metal cations. Among the examined catalysts, Sc(OTf)3 exhibits the highest catalytic activity. Fructose conversion of 100% and

Fenfen Wang; Ai-Wu Shi; Xiao-Xia Qin; Chun-Ling Liu; Wen-Sheng Dong

2011-01-01

262

Additional effects of rare earth elements on formation and properties of some transition metal pyrophosphates  

Microsoft Academic Search

Transition metal phosphates have been used as inorganic pigments. By the addition of rare earth elements, new functional materials are expected to form. In this work, rare earth oxides (Y2O3, La2O3, CeO2, and Nd2O3) were added in the formation systems of copper, manganese, and cobalt pyrophosphates prepared from ammonium dihydrogenphosphate and the transition metal carbonate. The thermal behaviors of the

Hiroaki Onoda; Kazuo Kojima; Hiroyuki Nariai

2006-01-01

263

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

264

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

265

Metal interactions with voltage- and receptor-activated ion channels.  

PubMed Central

Effects of Pb and several other metal ions on various distinct types of voltage-, receptor- and Ca-activated ion channels have been investigated in cultured N1E-115 mouse neuroblastoma cells. Experiments were performed using the whole-cell voltage clamp and single-channel patch clamp techniques. External superfusion of nanomolar to submillimolar concentrations of Pb causes multiple effects on ion channels. Barium current through voltage-activated Ca channels is blocked by micromolar concentrations of Pb, whereas voltage-activated Na current appears insensitive. Neuronal type nicotinic acetylcholine receptor-activated ion current is blocked by nanomolar concentrations of Pb and this block is reversed at micromolar concentrations. Serotonin 5-HT3 receptor-activated ion current is much less sensitive to Pb. In addition, external superfusion with micromolar concentrations of Pb as well as of Cd and aluminum induces inward current, associated with the direct activation of nonselective cation channels by these metal ions. In excised inside-out membrane patches of neuroblastoma cells, micromolar concentrations of Ca activate small (SK) and big (BK) Ca-activated K channels. Internally applied Pb activates SK and BK channels more potently than Ca, whereas Cd is approximately equipotent to Pb with respect to SK channel activation, but fails to activate BK channels. The results show that metal ions cause distinct, selective effects on the various types of ion channels and that metal ion interaction sites of ion channels may be highly selective for particular metal ions.

Vijverberg, H P; Oortgiesen, M; Leinders, T; van Kleef, R G

1994-01-01

266

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

National Technical Information Service (NTIS)

This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics unde...

H. Stauffer N. Pohl N. B. Lentz R. S. Housk V. S. Y. Lin

2007-01-01

267

[Rare-earth metals as a factor in mutagenicity].  

PubMed

Both the regions of the Orenburg Region area and individual examined streams and reservoirs were shown to be characterized by a varying load index for rare earth elements. The total level of rare earth elements was directly correlated with different types of mutations. PMID:23088115

Solovykh, G N; Golinskaia, L V; Kanunikova, E A

268

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

269

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

270

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

271

Ionization mechanism in a liquid-metal ion source. Source for high-melting metals  

Microsoft Academic Search

Investigations have been made of the ionization mechanism in a liquid-metal ion source. At the instant of ion current generation\\u000a the surface of a liquid metal emitter frozen in a highvoltage field exhibits microprotrusions pulled from the liquid metal\\u000a by the electric field. A double-focusing mass spectrometer identified two components in the ion beam extracted from the aperture\\u000a in the

G. G. Sikharulidze

1997-01-01

272

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

PubMed

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

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

2006-11-15

273

Scattering of field-aligned beam ions upstream of Earth's bow shock  

Microsoft Academic Search

Field-aligned beams are known to originate from the quasi-perpendicular side of the Earth's bow shock, while the diffuse ion population consists of accelerated ions at the quasi-parallel side of the bow shock. The two distinct ion populations show typical characteristics in their velocity space distributions. By using particle and magnetic field measurements from one Cluster spacecraft we present a case

A. Kis; M. Scholer; B. Klecker; H. Kucharek; E. A. Lucek; H. Rème

2007-01-01

274

Thermodynamic stability of perovskites and related compounds in some alkaline earth-transition metal-oxygen systems  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of some alkaline earth (A)-transition metal (M) perovskites and K2NiF4 compounds have been collected, analyzed, and utilized to examine their stabilities by constructing the chemical potential diagrams of a log [a(A)/a(M)] vs log P(O2) plot. A thermodynamic analysis was performed on the dissociation reaction of K2NiF4 compounds (A2MO4) into perovskites (AMO3) and alkaline earth oxides (AO) using empirical correlations between stabilization energy and tolerance factor. It has been found that the softness of calcium ions, which shrink markedly with decreasing coordination number from 12 to 9, makes the calcium K2NiF4 compounds (Ca2MO4) relatively less stable with increasing radius of the transition metal ions, r(M4+). This destabilization related to the coordination-number-dependent radii implies that when compared with the strontium perovskites, the calcium analogous perovskites may have a smaller number of oxygen vacancies, because the formation of oxygen vacancies should be accompanied with a decrease in coordination number of A-site ions.

Yokokawa, Harumi; Sakai, Natsuko; Kawada, Tatsuya; Dokiya, Masayuki

1991-09-01

275

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

SciTech Connect

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

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

1988-01-01

276

Purification of metal plating rinse waters with chelating ion exchangers  

Microsoft Academic Search

A wide range of chelating ion exchangers was tested for their abilities to remove Zn, Ni, Cu and Cd from solutions simulating waste effluents from the metal-plating industry. The task was to reduce metal discharges to the environment so that metal-plating shops could keep up with the modern, more stringent regulations of waste effluents. The resins were tested by batch

Risto Koivula; Jukka Lehto; Leena Pajo; Thomas Gale; Heikki Leinonen

2000-01-01

277

Ion Beam Superpolishing of Metal Mirrors for High Energy Lasers.  

National Technical Information Service (NTIS)

A new process has been developed which employs a low energy ion beam to superpolish metal surfaces. The process is applicable in principle to all metals. This technique overcomes the tendency of metal surfaces to develop etch patterns and other surface ir...

H. Gelles J. D. Lester R. T. Cook

1975-01-01

278

Adsorption of heavy metal ions on soils and soils constituents  

Microsoft Academic Search

The article focuses on adsorption of heavy metal ions on soils and soils constituents such as clay minerals, metal (hydr)oxides, and soil organic matter. Empirical and mechanistic model approaches for heavy metal adsorption and parameter determination in such models have been reviewed. Sorption mechanisms in soils, the influence of surface functional groups and surface complexation as well as parameters influencing

Heike B Bradl

2004-01-01

279

Operational characteristics of a metal vapor vacuum arc ion source  

SciTech Connect

The MEVVA ion source can produce high current pulsed beams of metallic ions using a metal vapor vacuum arc discharge as the plasma medium from which the ions are extracted. In this study, the operational characteristics of the MEVVA IV ion source are summarized. Results are presented of measurements of the ion beam current as a function of arc current over a range of extraction voltage. Ti, Ta and Pb were examined as the cathode materials. The arc current ranged from 50A to 250A and the extraction voltage from 10kV to 80kV. The ion beam current was measured at two different distances from the ion source using Faraday cups, so as to investigate the beam divergence. Additionally, the cathode erosion rates were measured. Optimum operating conditions of the MEVVA ion source were determined. 10 refs., 6 figs.

Shiraishi, Hiroshi; Brown, I.G. (Nippon Steel Corp., Kitakyushu (Japan); Lawrence Berkeley Lab., CA (USA))

1989-06-01

280

Applications of the MEVVA high current metal ion source  

SciTech Connect

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

Brown, I.G.

1986-08-01

281

Determination of Trace Metal Ion Concentrations in Seawater  

NASA Astrophysics Data System (ADS)

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

Quigley, Michael N.; Vernon, Fredrick

1996-07-01

282

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

283

Novel preorganized hemispherands to encapsulate rare earth ions: shielding and ligand deuteration for prolonged lifetimes of excited Eu3+ ions  

Microsoft Academic Search

Quenching of the luminescent excited state of Eu3+ ions by C-H high-vibrational modes was studied by deuteration of the encapsulating ligand and the solvent. Novel polydentate hemispherands providing nine donor atoms, which form overall neutral complexes with rare earth ions, were synthesized in nine steps, allowing the easy incorporation of deuterium atoms (11a-d·Eu3+). The introduction of tert-butyl groups at the

Manon P. Oude Wolbers; Veggel van Frank C. J. M; Bianca H. M. Snellink-Ruel; Johannes W. Hofstraat; Frank A. J. Geurts; David N. Reinhoudt

1997-01-01

284

Grids for maintenance-free storage batteries made from lead-akaline earth metal-alloys  

Microsoft Academic Search

The production of lead-alkaline earth metal grids for use in acid-based batteries was investigated. Rolled strips of the alloy were processed into expanded metal grids showing sufficient mechanical strength, high electrical conductivity, and corrosion resistance. Batteries using these electrodes are maintenance-free and exhibit good cold cranking ability.

U. Heubner; G. Friedham; E. Nann

1979-01-01

285

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

286

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

287

Frothless ion flotation of some rare earth elements  

Microsoft Academic Search

Investigations on frothless ion flotation of europium, thulium, and ; ytterbium in the form of microcolloidal hydroxides from aqueous ammonium chloride ; solutions, and also in the form of anionic complexes with citric acid, as a ; function of flotation time, hydrogen ions, NHâCl, and citric acid ; concentrations were carried out. Anionic and cationic detergents sodium ; tetradecyl sulphate

Z. Szeglowski; M. Bitner-Jankowska; J. Mikulski

1973-01-01

288

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

289

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

2012-11-23

290

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

291

Searching for new luminescent chemosensors for metal ions  

NASA Astrophysics Data System (ADS)

Aiming to develop new fluorescent chemosensors for biological and environmental applications, we have designed and synthesized new chemical species able to reversibly bind alkali, earth-alkali, and transition metal ions. For signaling the binding of the target analyte, we have inserted in the structure of the chemosensors different luminophores, such as dioxyxanthone derivatives, dansyl derivatives, ruthenium complexes, and hydroxyquinoline derivatives. In solution, the binding is always signaled by pronounced changes in the photophysical properties of the inserted luminophore such as emission wavelength and intensity, and excited state lifetime. The mechanism for the signal transduction strongly depends on the chosen receptor and luminophore moieties, and has been investigated in detail by means of steady state and time resolved spectroscopy. In all cases, the synthesized chemosensors have proved to be chemically and photochemically stable. Good selectivity and affinity has been obtained with different sensors for K+, Mg2+, Ba2+, Zn2+, Ni2+ and Cu2+, even in physiological pH conditions. Moreover the use of an array of these sensors in optodes could lead to the construction of the so called electronic tongues. All these features make these sensors promising candidates for analytical applications.

Prodi, Luca; Bolletta, Fabrizio; Montalti, Marco; Zaccheroni, Nelsi

1999-05-01

292

SELECTION AND EVALUATION OF RARE OR UNUSUAL METALS. PART II. THE METALLURGY OF YTTRIUM AND THE RARE EARTH METALS. Period covered: October 1957 to October 1958. METALLIC MATERIALS. Task title: UNIQUE METALLIC MATERIALS AND PROCESSES  

Microsoft Academic Search

Studies were made of yttrium and the rare-earth metals and of alloys of ; titanium and beryllium with rare-earth additions. Improved methods for the ; production of pure metals are described. A complete metallographic procedure has ; been developed. Procedures for the chemical and spectrographic analysis of ; metals and alloys are provided including a method for oxygen analysis. The

Love

1958-01-01

293

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

294

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

Microsoft Academic Search

The techniques of time-of-flight mass spectrometry and negative ion photoelectron spectroscopy were utilized to study metal clusters (Mgn -, Znn-, Can -, Mnn-, CuAln -, LiAln-, and NmSn n-), metal-organic complexes (Tin(benzene) m-, Fn(benzene)m- , Nin(benzene)m-), metal oxides(AuO-, PtO-, TaOn -, HfO2-, and MnnO -), and metal-doped semiconductor clusters (CrSin -, GdmSin- and HoSi n-). The study of magnesium and

Weijun Zheng

2005-01-01

295

Heating of metals in swift heavy ion tracks by electron-ion energy exchange  

Microsoft Academic Search

The rate of the heat transfer from the excited electrons to the ion lattice in swift heavy ion tracks in metals considerably deviates from the predictions of the electron-phonon coupling model. Due to the short times of the electron gas cooling down this rate is insensitive to a particular atomic structure of irradiated metals. For the initial temperature of the

A. E. Volkov; V. A. Borodin

1998-01-01

296

Heating of metals in swift heavy ion tracks by electron–ion energy exchange  

Microsoft Academic Search

The rate of the heat transfer from the excited electrons to the ion lattice in swift heavy ion tracks in metals considerably deviates from the predictions of the electron-phonon coupling model. Due to the short times of the electron gas cooling down this rate is insensitive to a particular atomic structure of irradiated metals. For the initial temperature of the

A. E. Volkov; V. A. Borodin

1998-01-01

297

The Sol-Gel Synthesis of Rare-Earth Ions Substituted Barium Hexaferrites and Magnetic Properties  

NASA Astrophysics Data System (ADS)

In this paper, a series of rare-earth-doped barium hexaferrite powders (Ba0.95Re0.05-Fe12O19 and Ba0.95Re0.05M0.05Fe11.95O19: Re = La, Pr, Sm, Nd, Gd, Dy, Yb; M = Zn2+, Mn2+, Mn0.52+Zn2+0.5) were synthesized by the sol-gel self-combustion technology. The phase composition and the magnetic properties of the as-prepared barium hexaferrites were characterized and discussed with X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results showed that the barium hexaferrites exhibited the magnetoplumbite phase structure with the average diameter of 45 nm. Magnetic properties study revealed that the variation of the saturation magnetization (Ms) was similar with the change of the rare-earth ions radius, but the change of Ms was low. This indicated that the magnetic moments of rare-earth ions could not affect Ms. The magnetocrystalline anisotropy field mainly influenced the anisotropism of hexaferrites, and the coercivity (Hc) of the rare-earth ions doped barium hexaferrites basically decreased with the increasing orbital quantum numbers (except Sm3+ and Gd3+). Further study showed the co-addition of Zn2+ and Mn2+ did not change the trend of Ms and Hc. Thus, it is concluded that the rare-earth ions played an important role for the anisotropy field of barium hexaferrites.

Cai, S.; Xin, P. H.; Wang, P. F.; Zhang, B. B.; Han, Y. B.; Peng, X. L.; Hong, B.; Jin, H. X.; Gong, J.; Jin, D. F.; Ge, H. L.; Wang, X. Q.; Zhang, J.

2013-10-01

298

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

299

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

2010-03-10

300

Metal ion binding and the folding of the hairpin ribozyme.  

PubMed Central

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

Wilson, Timothy J; Lilley, David M J

2002-01-01

301

Relativistic Effect on Multiplet Terms of Rare Earth Ions  

Microsoft Academic Search

Ab initio Spin-Orbit Configuration Interaction (SOCI) calculations for the trivalent lanthanide group ions are presented for the special purpose to investigate the relativistic SO effects on their multiplet terms. The effective nuclear charges (Z eff's) for one-body spin-orbit Hamiltonian are calculated by an atomic Dirac-Slater Xalpha equation and applied to the lanthanide ions. The relativistic effects of core electrons can

Shinichi Itoh; Riichiro Saito; Tadamasa Kimura; Satoshi Yabushita

1994-01-01

302

Ion exchange extraction of heavy metals from wastewater sludges.  

PubMed

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

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

2004-01-01

303

Determination of metal ions by ion chromatography with precolumn electrochemical preconcentration  

Microsoft Academic Search

The determination of heavy metals in concentrations less than 10-6 mol\\/L by ion chromatography with conductivity detection requires a preconcentration step. Therefore, a special electrochemical equipment and method was developed for the on-line preconcentration of the divalent metals Ni, Co, Zn and Cd and their subsequent ion chromatographic determination. The loop of the injection valve of an ion chromatograph was

Frank Hißner; Jürgen Mattusch; G. Werner

1996-01-01

304

Effects of metal ions on fibroblasts and spiral ganglion cells.  

PubMed

Degeneration of spiral ganglion cells (SGC) after deafness and fibrous tissue growth around the electrode carrier after cochlear implantation are two of the major challenges in current cochlear implant research. Metal ions are known to possess antimicrobial and antiproliferative potential. The use of metal ions could therefore provide a way to reduce tissue growth around the electrode array after cochlear implantation. Here, we report on in vitro experiments with different concentrations of metal salts with antiproliferative and toxic effects on fibroblasts, PC-12 cells, and freshly isolated spiral ganglion cells, the target cells for electrical stimulation by a cochlear implant. Standard cell lines (NIH/3T3 and L-929 fibroblasts and PC-12 cells) and freshly isolated SGC were incubated with concentrations of metal ions between 0.3 ?mol/liter and 10 mmol/liter for 48 hr. Cell survival was investigated by neutral red uptake, CellQuantiBlue assay, or counting of stained surviving neurons. Silver ions exhibited distinct thresholds for proliferating and confluent cells. For zinc ions, the effective concentration was lower for fibroblasts than for PC-12 cells. SGC showed comparable thresholds for reduced cell survival not only for silver and zinc ions but also for copper(II) ions, indicating that these ions might be promising for reducing tissue growth on the surface of CI electrode arrays. These effects were also observed when combinations of two of these ions were investigated. PMID:21312225

Paasche, G; Ceschi, P; Löbler, M; Rösl, C; Gomes, P; Hahn, A; Rohm, H W; Sternberg, K; Lenarz, T; Schmitz, K-P; Barcikowski, S; Stöver, T

2011-01-13

305

Effects of metal ions on fibroblasts and spiral ganglion cells.  

PubMed

Degeneration of spiral ganglion cells (SGC) after deafness and fibrous tissue growth around the electrode carrier after cochlear implantation are two of the major challenges in current cochlear implant research. Metal ions are known to possess antimicrobial and antiproliferative potential. The use of metal ions could therefore provide a way to reduce tissue growth around the electrode array after cochlear implantation. Here, we report on in vitro experiments with different concentrations of metal salts with antiproliferative and toxic effects on fibroblasts, PC-12 cells, and freshly isolated spiral ganglion cells, the target cells for electrical stimulation by a cochlear implant. Standard cell lines (NIH/3T3 and L-929 fibroblasts and PC-12 cells) and freshly isolated SGC were incubated with concentrations of metal ions between 0.3 ?mol/liter and 10 mmol/liter for 48 hr. Cell survival was investigated by neutral red uptake, CellQuantiBlue assay, or counting of stained surviving neurons. Silver ions exhibited distinct thresholds for proliferating and confluent cells. For zinc ions, the effective concentration was lower for fibroblasts than for PC-12 cells. SGC showed comparable thresholds for reduced cell survival not only for silver and zinc ions but also for copper(II) ions, indicating that these ions might be promising for reducing tissue growth on the surface of CI electrode arrays. These effects were also observed when combinations of two of these ions were investigated. © 2011 Wiley-Liss, Inc. PMID:21234893

Paasche, G; Ceschi, P; Löbler, M; Rösl, C; Gomes, P; Hahn, A; Rohm, H W; Sternberg, K; Lenarz, T; Schmitz, K-P; Barcikowski, S; Stöver, T

2011-01-13

306

Extracting metal ions with diphosphonic acid, or derivative thereof  

DOEpatents

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

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

1994-01-01

307

Kinetic Analysis of Metal Ions: An Undergraduate Laboratory Experiment.  

ERIC Educational Resources Information Center

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

Williams, Kathryn R.

1985-01-01

308

Defect Production and Electronic Stopping for Light Ions in Metals.  

National Technical Information Service (NTIS)

A method for determining effective electronic stopping powers in metals is presented. The method involves measuring damage rates in thin films as a function of ion energy. The experimental results are compared with predictions based on Monte Carlo compute...

R. S. Averback R. Benedek K. L. Merkle L. J. Thompson

1979-01-01

309

Catalytic Oxidation by Transition Metal Ions in Zeolites.  

National Technical Information Service (NTIS)

The regular cavities of zeolites form a unique environment for carrying out both stoichiometric and catalytic oxidation reactions. Transition metal ions such as molybdenum and cobalt may be introduced into the zeolite, and, as well, the acidity may be var...

J. H. Lunsford

1988-01-01

310

High-current metal ion beam extraction from a multicusp ion source  

Microsoft Academic Search

Improvements have been made in a multicusp ion source, which made it possible to produce metal–vapor plasma and extract a high-current metal ion beam. In the discharge chamber, double radiation shields were set and the inner shields were heated to 1860 K. Therefore, it became possible to maintain enough metal–vapor density to produce plasma without the use of support gas.

Yutaka Inouchi; Hideki Tanaka; Hiroshi Inami; Fumio Fukumaru; Kouzi Matsunaga

1990-01-01

311

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

312

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

Microsoft Academic Search

A lens system for a large current liquid metal ion source has been designed by a numerical computer simulation method. As a computed result, the lens system can focus an ion beam having an emission angle of 60° to a beam having a radius of 1.8 mm at 1 m from the ion source. Following the simulated result, the lens

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

1990-01-01

313

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

Microsoft Academic Search

This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types\\/ratios

Nicholas B. Lentz

2007-01-01

314

Transport toward earth of ions sputtered from the moon's surface by the solar wind  

NASA Astrophysics Data System (ADS)

The transport of typical ions from the surface of the Moon to the vicinity of Earth was calculated using a test particle approach. It was assumed that the ions were sputtered from the surface by the solar wind, with fluxes in the range determined experimentally by Elphic et al. (1991), and were accelerated initially to 10 eV by the potential of the Moon on its sunlit side. Si(+) and Ca(+) ions were selected for this transport analysis because their masses are within two prominent ion mass groups that have high sputtering yields. In the solar wind the ion trajectories were traced in the following superimposed fields: (1) a steady magnetic field B0 at an angle of 45 deg to the solar wind velocity VSW, (2) the motional electric field Ezero = -V(sub SW x B0, and (3) turbulent magnetic and electric fields generated by hydromagnetic waves with a k-space power spectrum of absolute value of k-5/3 propagating along both directions of the magnetic field B0. Interactions with Earth's bow shock and magnetosphere were included. Case histories of the ions were recorded in the XGSM, YGSM plane and in various planes perpendicular to the E0 x B0 drift direction of the ions between the Moon and Earth. The number density, energy and angular distributions, and directional and omnidirectional fluxes of the ions were constructed from the case histories. It was found that the diffusion of the ions increases rapidly as the amplitude of the turbulence delta Brms increases beyond the value 0.04 B0. Recent measurements of lunar ions upstream of the bow shock by Hilchenbach et al. (1992) generally confirm the predicted behavior of the ions.

Cladis, J. B.; Francis, W. E.; Vondrak, R. R.

1994-01-01

315

Ion metal synthesis in viscous organic matter  

Microsoft Academic Search

The viscosity of the irradiated target as new parameter was introduced in ion implantation physics of organic matter. It was experimentally shown that using this parameter one enables to monitor the process of ion synthesis of thin granular impurity films. As an example, the results of high-dose implantation of Co+ and Ag+ ions in viscous epoxy experimenting stages of cure

I. B. Khaibullin; R. I. Khaibullin; S. N. Abdullin; A. L. Stepanov; Yu. N. Osin; V. V. Bazarov; S. P. Kurzin

1997-01-01

316

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

317

Study of a liquid metal ion source for external ion injection into electron-beam ion source  

NASA Astrophysics Data System (ADS)

A liquid metal ion source (LMIS) has several attractive features as an external injector of primary ions (mostly metallic ions) into electron-beam ion source (EBIS). It does not use a buffer gas and therefore it provides only a very small gas load to the system; its control and operation are simple, power consumption does not exceed 10 W, and beam pulses are very stable. A gold-silicon LMIS was supplied by FEI Company (http://www.feibeamtech.com/pages/liquid.html) and tested in a pulsed regime with an ion pulse width of 2 ms and frequency up to 5 Hz. Total extracted ion current reached 50 ?A and the normalized emittance of the total ion beam was 0.05? mm mrad. The results of this test, as well as results of experiments in which this ion source is used for injection of Au ions into EBIS, are presented.

Pikin, A.; Alessi, J. G.; Beebe, E. N.; Kponou, A.; Prelec, K.

2006-03-01

318

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

319

The Physics of Thermomagnetic Recording in Thin Films of Rare Earth-Transition Metal Alloys  

NASA Astrophysics Data System (ADS)

The goal of this research is to better understand the dynamic phenomena occurring during the writing and erasure processes. A domain wall motion model is proposed. The relationship of the wall velocity to the effective pressure on the wall and the mobility is given. Computer simulation is used to directly calculate the transient position of the wall. In general, the motion of the domain wall is governed by the wall mobility. The domain wall mobility for amorphous alloys of rare earth-transition metal thin films has been measured at high temperatures by means of the dynamic bubble collapse method for films in the (Gd,Tb)(Fe,Co) system. The domain wall velocity is linearly proportional to the applied field if the field is significantly larger than the coercivity. The mobility increases slightly with temperature. Increasing the ratio of Gadolinium to Terbium significantly raises the value of the mobility. Local fluctuations of the magnetic properties in amorphous alloys, specifically the random anisotropy, cause irregularity in the domain shape and writing noise. A model for coercivity based on the pinning of domain walls by the randomly fluctuating anisotropy is proposed. This model is particularly suitable for materials containing non S-state rare earth ions like terbium. The new coercive force model is used to predict the domain shape during the growth process. Wall motion near the magnetization and angular momentum compensation temperatures is modeled. When a domain wall gets close to the compensation temperatures the structure of the wall and its dynamic properties are changed. In alloys having angular momentum compensation temperatures above the ambient temperature domain erasure can be achieved without an applied field. In some cases erasure is still possible even with a field applied in a direction favoring the write process. Anomalous wall dynamics, which occur when the angular momentum is compensated, are believed to be responsible for the erase process in single layer direct overwrite magneto-optical recording media. (Abstract shortened with permission of author.).

Weng, Robert Shaw-Tzuu

320

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

321

REVIEW: Intermetallic compounds of rare earths and non-magnetic metals  

Microsoft Academic Search

A review is given of the physical properties, composition and crystal structure of intermetallic compounds formed between rare-earth elements and non-magnetic metals, with emphasis on the magnetic properties. Included are the properties of compounds in which the non-rare-earth component is a 4d or 5d transition element. Special consideration is given to the properties of pseudo-binary compounds. Results of magnetisation measurements,

K. Buschow

1979-01-01

322

Indirect Exchange Coupling of Magnetic Moments in Rare-Earth Metals  

Microsoft Academic Search

The Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange mechanism is examined for its relevance to ferromagnetism in the rare-earth metals. More specifically, the experimental sensitivity of the exchange energy (or Curie temperature) to the interatomic spacing (applied pressure) of the rare earths is examined in terms of the RKKY interaction. The form in which the interaction is usually examined, i.e., with the coupling parameter

Lawrence Baylor Robinson; Lloyd N. Ferguson; Frederick Milstein

1971-01-01

323

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

324

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

325

Molten Salt Oxidation of Ion-exchange Resins Doped with Toxic Metals and Radioactive Metal Surrogates  

Microsoft Academic Search

Ion-exchange resins doped with toxic metals and radioactive metal surrogates were test-burned in a bench-scale molten salt oxidation (MSO) reactor system. The purposes of this study are to confirm the destruction performance of the two-stage MSO reactor system for the organic ion-exchange resin and to obtain an understanding of the behavior of the fixed toxic metals and the sulfur in

Hee-Chul YANG; Yong-Jun CHO; Hee-Chul EUN; Jae-Hyung YOO; Joon-Hyung KIM

2005-01-01

326

Electronic shielding of the crystalline electric field in rare earth ions  

Microsoft Academic Search

The effect of electronic shielding on the A20 term of the crystal field potential of the Pr3+ and the Tm3+ ion has been estimated from the numerical solution of the first-order perturbation equation. The shielding factor ?2 is 0.59 and 0.70 for Tm3+ and Pr3+ respectively. The results stress the importance of electronic shieldings in rare-earth ions in agreement with

M. N. Ghatikar; A. K. Raychaudhuri; D. K. Ray

1965-01-01

327

Electronic shielding of the crystalline electric field in rare earth ions  

Microsoft Academic Search

The effect of electronic shielding on the A20 term of the crystal field potential of the Pr3+ and the Tm3+ ion has been estimated from the numerical solution of the first-order perturbation equation. The shielding factor sigma2 is 0.59 and 0.70 for Tm3+ and Pr3+ respectively. The results stress the importance of electronic shieldings in rare-earth ions in agreement with

M. N. Ghatikar; A. K. Raychaudhuri; D. K. Ray

1965-01-01

328

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

Microsoft Academic Search

Simultaneous measurements of the small, intermediate and large positive ions and air-Earth current density made at a coastal station, Maitri (70°45?52?S, 11°44?03?E, 130 m above sea level), at Antarctica during January–February 2005, are reported. Although small and large positive ion concentrations do not show any systematic diurnal variations, variations in them are almost similar to each other. On the other

Devendraa Siingh; Vimlesh Pant; A. K. Kamra

2007-01-01

329

ISEE Ion Composition Data with Implications for Solar Wind Entry into Earth's Magnetotail  

Microsoft Academic Search

Energetic (0.1-16 keV\\/e) ion data from a plasma composition experiment on the ISEE-1 spacecraft show that Earth's plasma sheet (inside of 23 RE) always has a large population of H+ and He++ ions, the two principal ionic components of the solar wind. This population is the largest, in terms of both number density and spatial thickness, during extended periods of

O. W. Lennartsson

1997-01-01

330

Measurement of hyperfine coupling constants of singly ionized rare earth ions  

Microsoft Academic Search

Hyperfine structure spectra of singly ionized rare earth ions were measured by collinear fast-ion-beam laser spectroscopy. Hyperfine structures in the range of 560-620nm were well resolved. The magnetic dipole coupling constants and electric quadrupole coupling constants of the excited levels and metastable levels in 139La+, 141Pr+, 143,145Nd+, 151,153Eu+, and 159Tb+ were determined.

H. L. Ma; F. J. Yang

2004-01-01

331

Measurement of hyperfine coupling constants of singly ionized rare earth ions  

Microsoft Academic Search

Hyperfine structure spectra of singly ionized rare earth ions were measured by collinear fast-ion-beam laser spectroscopy. Hyperfine structures in the range of 560–620nm were well resolved. The magnetic dipole coupling constants and electric quadrupole coupling constants of the excited levels and metastable levels in 139La+, 141Pr+, 143,145Nd+, 151,153Eu+, and 159Tb+ were determined.

H. L. Ma; F. J. Yang

2004-01-01

332

Observations of nonadiabatic acceleration of ions in Earth's magnetotail  

NASA Astrophysics Data System (ADS)

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

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

1994-08-01

333

Determination of metallic germanium in rare earth germanates  

Microsoft Academic Search

Metallic germanium can be determined by making use of its low oxidation-; reduction potential. In the pres ence of oxidizing agents STAV(V) and Fe(III)! ; metallic germanium will dissolve in acidic media and an equivalent amount of ; oxidant used will be reduced. Hydrochloric acid was used for decomposition when ; Fe(III) was the oxidant; sulfuric acid and a mixture

M. M. Piryutko; T. G. Kostyreva

1972-01-01

334

Synthesis and characterization of alkaline-earth-metal. beta. -diketonate complexes used as precursors for chemical vapor deposition of thin-film superconductors  

SciTech Connect

Several of the {beta}-diketonate metal complexes used for metal organic chemical vapor deposition (MOCVD) of thin-film superconductors have been characterized by thermogravimetric analysis, mass spectrometry, and gas chromatography/mass spectrometry. The volatility of the alkaline-earth-metal chelates has been studied, and it has been determined that one reason the alkaline-earth-metal chelates are less volatile than other metal {beta}-diketonates is that they exist as oligomers. For example, one barium {beta}-diketonate chelate consists of a cluster of five metal ions bridged by {beta}-diketonate carbonyl oxygens and water molecules. It has also been found that the addition of uncomplexed (protonated) {beta}-keto enolate ligand to the carrier gas stream greatly improves the gas chromatographic behavior of these alkaline-earth-metal chelates, probably owing to adduct formation accompanying the dissociation of the oligomers. The results of these studies, as well as the implications for using these chelates together with auxiliary ligands for MOCVD, will be discussed. 3 tables, 5 figs., 26 refs.

Turnipseed, S.B.; Barkley, R.M.; Sievers, R.E. (Univ. of Colorado, Boulder (USA))

1991-03-01

335

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

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

336

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

337

SEPARATION OF CERTAIN METAL IONS FROM MIXTURES BY ELECTROCHROMATOGRAPHY  

Microsoft Academic Search

The ions of one or a few metals were separated from multicomponent ; mixtures by one-way electrochromatography. The separation of particular ions is ; based upon differential electrical migration in stabilized solutions of specially ; selected background electrolytes. These methods, which have several advantages ; over chemical methods of segregation, permitted the isolation and idertification ; of one or a

Joseph Sherma; G. H. Evans; H. D. Jr. Frame; H. H. Strain

1963-01-01

338

Modification of medical metals by ion implantation of copper  

NASA Astrophysics Data System (ADS)

The effect of copper ion implantation on the antibacterial activity, wear performance and corrosion resistance of medical metals including 317 L of stainless steels, pure titanium, and Ti Al Nb alloy was studied in this work. The specimens were implanted with copper ions using a MEVVA source ion implanter with ion doses ranging from 0.5 × 1017 to 4 × 1017 ions/cm2 at an energy of 80 keV. The antibacterial effect, wear rate, and inflexion potential were measured as a function of ion dose. The results obtained indicate that copper ion implantation improves the antibacterial effect and wear behaviour for all the three medical materials studied. However, corrosion resistance decreases after ion implantation of copper. Experimental results indicate that the antibacterial property and corrosion resistance should be balanced for medical titanium materials. The marked deteriorated corrosion resistance of 317 L suggests that copper implantation may not be an effective method of improving its antibacterial activity.

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

2007-10-01

339

Rate Processes in Solvent Extraction of Metal Ion  

Microsoft Academic Search

The mechanism and kinetics of metal extraction with several extractants, including chelating agents, acidic organophosphorous extractant and neutral extractants are discussed in this paper.Firstly the extraction rate of metal ion for the general extraction system is formulated by solving the diffusional equation with chemical reaction, in which the interfacial reaction is considered by the boundary conditions. The overall rate expressions

YOSHIKAZU MIYAKE; YOSHINARI BABA

2000-01-01

340

Current and prospective applications of metal ion–protein binding  

Microsoft Academic Search

Since immobilized metal ion affinity chromatography (IMAC) was first introduced, several variants of this method and many other metal affinity-based techniques have been devised. IMAC quickly established itself as a highly reliable purification procedure, showing rapid expansion in the number of preparative and analytical applications while not remaining confined to protein separation. It was soon applied to protein refolding (matrix-assisted

E. K. M Ueda; P. W Gout; L Morganti

2003-01-01

341

Oxidative mechanisms in the toxicity of metal ions  

Microsoft Academic Search

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

S. J. Stohs; D. Bagchi

1995-01-01

342

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

Microsoft Academic Search

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

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

2006-01-01

343

Xmcd at the 3d Metal K-Edge in Rare Earth-Transition Metal Alloys:. Influence of the Rare Earth  

NASA Astrophysics Data System (ADS)

In ferro- or ferrimagnetic systems x-ray magnetic circular dichroism (XMCD) can yield information on the magnetic contribution of each open orbitals for each species. In rare-earth-3d transition-metal (R-T) alloys these orbitals are of utmost interest for magnetism as they originate the magnetic moments (4f in rare earth, 3d in transition metal) or mediate the magnetic interactions (d or p bands). Despite intensive works the interpretation is still matter of discussion at the R L2,3-edges and T K-edge. We present here a comparative study of the XMCD at the 3d metal K-edge in several R-T compounds where the 3d metal satisfies (RCo5) or not (RNi5) the Stoner criterion. The structure of the experimental XMCD spectra in the near-edge region has been observed to be sensitive to the magnetic environment of the absorbing site. Calculations of the XMCD spectra have also been performed for pure Co metal, LaCo5, TbCo5, TbCo2 and HoCo2, within the multiple scattering framework including the spin-orbit coupling. The spectra are well reproduced in the near-edge region. Results point out that the near-edge structures in the Co K-edge XMCD spectra originates almost exclusively from the spin-orbit on the R 5d states when R is magnetic.

Galera, R. M.; Chioncel, L.; Rueff, J. P.; Rogalev, A.; Giorgetti, Ch.; Dartyge, E.; Brouder, Ch.; Alouani, M.

2000-09-01

344

On Field-aligned Ion Beams in the Earth's Foreshock Region  

Microsoft Academic Search

The foreshock global morphology is organized by the interplanetary magnetic field direction, the bow shock shape, and, crucially, by particle dynamics. All physical processes at and around the Earth's bow are collisionless and the ion dynamic is determined by the wave-particle interactions. Particles are reflected and energized at the shock and some with high speeds are able to propagate upstream

H. Kucharek

2007-01-01

345

Sun–Earth geometry, geomagnetic activity, and planetary F2 layer ion density  

Microsoft Academic Search

Our previous quantitative analyses have shown that geomagnetic activity and planetary ion density of the F2 layer of the ionosphere seem to share the same parent cause, the solar wind, whose entry into geospace is controlled by the Sun–Earth geometry. The thrust of this paper is four fold: (a) to establish the reality of this not clearly recognized connection, (b)

Chaman-Lal

2000-01-01

346

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

NASA Astrophysics Data System (ADS)

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

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

1983-03-01

347

Pitch angle distributions of low-energy ions in the near-earth magnetosphere  

NASA Astrophysics Data System (ADS)

Energetic ion composition data acquired by satellite have been used to study the characteristics of ion pitch angle distributions in the near-earth magnetosphere. Both H(+) and O(+) ions below 1 keV were most frequently observed to have bidirectional field-aligned or conical pitch angle distributions inside L of about 6, with the exception of highly trapped H(+) very near the magnetic equator. The occurrence probability distributions of counterstreaming ions (CSI) and bidirectional conics in magnetic local time and L shell space suggest that the observed CSI were formed near the postmidnight sector and subsequently drifted eastward, and that ions close to the field-aligned direction were probably lost due to charge exchange with atmospheric hydrogen in the course of their eastward drift. In the prenoon sector, conical distributions dominated. Bidirectional ions were vary rarely observed in the afternoon sector, presumably because their drift paths crossed the magnetopause into the dayside magnetosheath.

Sagawa, E.; Yau, A. W.; Whalen, B. A.; Peterson, W. K.

1987-11-01

348

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

349

Biosorption of precious metal ions by chicken feather  

Microsoft Academic Search

Chicken feather (C-feather) is an intricate network of stable and water-insoluble protein fibers with high surface area and\\u000a is an abundant bioresource. C-feather protein was found to accumulate various precious metal ions (gold and platinum metals)\\u000a selectively from their dilute aqueous solutions in high yield and in short contact time, depending on pH and characteristics\\u000a of the individual precious metal

Kyozo Suyama; Yoshitaka Fukazawa; Hiroshi Suzumura

1996-01-01

350

High-current-density metal-ion implantation  

Microsoft Academic Search

Design features and preliminary performance data for an ion-implantation system that derives its broad, high-current-density beam directly from a steady, metal-plasma discharge in a high temperature graphite chamber are described. Metal vapor is supplied by drawing electron current to an anode-potential crucible to vaporize a pure metal in it. Argon used to start the discharge is turned off once sufficient

Paul J. Wilbur; Ronghua Wei

1992-01-01

351

Forcing Ferromagnetic Coupling Between Rare-Earth-Metal and 3d Ferromagnetic Films  

NASA Astrophysics Data System (ADS)

Using density functional calculations, we have studied the magnetic properties of nanocomposites composed of rare-earth-metal elements in contact with 3d transition metals (Fe and Cr). We demonstrate the possibility to obtain huge magnetic moments in such nanocomposites, of order 10?B/rare-earth-metalatom, with a potential to reach the maximum magnetic moment of Fe-Co alloys at the top of the so-called Slater-Pauling curve. A first experimental proof of concept is given by thin-film synthesis of Fe/Gd and Fe/Cr/Gd nanocomposites, in combination with x-ray magnetic circular dichroism.

Sanyal, Biplab; Antoniak, Carolin; Burkert, Till; Krumme, Bernhard; Warland, Anne; Stromberg, Frank; Praetorius, Christian; Fauth, Kai; Wende, Heiko; Eriksson, Olle

2010-04-01

352

Surgical Variables Influence Metal Ion Levels After Hip Resurfacing  

Microsoft Academic Search

Background  Metal-on-metal bearings in surface arthroplasty are associated with prolonged periods of elevated ion circulation. However,\\u000a there exists some controversy regarding the effect of different surgical variables on the concentration of metal ions in whole\\u000a blood of patients after hip resurfacing.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We sought to confirm which clinical and radiographic parameters are associated with elevated levels of cobalt, chromium, and\\u000a molybdenum after

Nicholas M. Desy; Stephane G. Bergeron; Alain Petit; Olga L. Huk; John Antoniou

2011-01-01

353

Ion source metal-arc fault current protection circuit  

SciTech Connect

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

deVries, G.J.; Lietzke, A.F.; van Os, C.F.A.; Stearns, J.W. (Lawrence Berkeley Laboratory, University of California, Berkeley, California (USA))

1991-12-01

354

Neutralization by metal ions of the toxicity of sodium selenide.  

PubMed

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

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

2013-01-14

355

Improved Ion-Exchange Separation of Rare-Earth Elements for Spectrographic Analysis.  

National Technical Information Service (NTIS)

Rare-earth elements are separated from scandium and base metals by adsorption onto anion resin BIORAD AG1-X8 in the nitrate form from a mixture of 5% 7 M nitric acid and 95% methanol. The yttrium subgroup is eluted with a mixture of 45% 7 M nitric acid an...

E. A. Jones

1978-01-01

356

Titanates deliver metal ions to human monocytes.  

PubMed

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

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

2009-11-26

357

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, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

1988-08-26

358

Metal ion implantation in inert polymers for strain gauge applications  

NASA Astrophysics Data System (ADS)

Metal ion implantation in inert polymers may produce ultra-thin conducting films below the polymer surface. These subsurface films are promising structures for strain gauge applications. To this purpose, polycarbonate substrates were irradiated at room temperature with low-energy metal ions (Cu+ and Ni+) and with fluences in the range between 1 × 1016 and 1 × 1017 ions/cm2, in order to promote the precipitation of dispersed metal nanoparticles or the formation of a continuous thin film. The nanoparticle morphology and the microstructural properties of polymer nanocomposites were investigated by glancing-incidence X-ray diffraction and transmission electron microscopy (TEM) measurements. At lower fluences (<5 × 1016 ions/cm2) a spontaneous precipitation of spherical-shaped metal nanoparticles occurred below the polymer top-surface (˜50 nm), whereas at higher fluences the aggregation of metal nanoparticles produced the formation of a continuous polycrystalline nanofilm. Furthermore, a characteristic surface plasmon resonance peak was observed for nanocomposites produced at lower ion fluences, due to the presence of Cu nanoparticles. A reduced electrical resistance of the near-surface metal-polymer nanocomposite was measured. The variation of electrical conductivity as a function of the applied surface load was measured: we found a linear relationship and a very small hysteresis.

di Girolamo, Giovanni; Massaro, Marcello; Piscopiello, Emanuela; Tapfer, Leander

2010-10-01

359

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

360

Magnetic studies of nickel ferrite doped with rare earth ions  

NASA Astrophysics Data System (ADS)

The magnetic properties nickel ferrites having general chemical formula Ni x Fe(3 - x)O4 have been studied. The X-ray diffraction measurements confirmed the formation of a cubic spinel structure. The magnetic properties were studied by vibrating sample magnetometer (VSM). It exhibited lower coercivity and higher saturation magnetization due to high crystallinity. The saturation magnetization ( M s) and coercivity ( H c) for Nd and Gd are different ions since the magnetic moment of Gd3+ is greater than Nd3+.

Mahalakshmi, S.; Srinivasa Manja, K.; Nithiyanantham, S.; Rajah, Mohan

2013-11-01

361

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

SciTech Connect

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

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

1993-06-07

362

Rashba effect at the surfaces of rare-earth metals and their monoxides  

Microsoft Academic Search

We present a systematic study of the Rashba-type spin-orbit interaction at the (0001) surfaces of rare-earth metals and their surface monoxides, specifically of Tb metal and the O\\/Tb, O\\/Lu and O\\/Y surfaces. By means of photoemission experiments and ab initio band-structure calculations, we uncover the influence of this interaction on the surface electronic structure. In turn, the dramatic impact of

O. Krupin; G. Bihlmayer; K. M. Döbrich; J. E. Prieto; K. Starke; S. Gorovikov; S. Blügel; S. Kevan; G. Kaindl

2009-01-01

363

Magnetic Effects of Rare-Earth Impurities on Electron Transport in the Noble Metals  

Microsoft Academic Search

Of the dilute alloys of rare-earth metals in the noble metals, only a few show a small resistance anomaly and a temperature-dependent negative magnetoresistance at liquid-helium temperatures. In a saturating magnetic field the decrease for the Gd alloys is 2%. A calculation in Born approximation shows this to be due to interference between Coulomb and spin-dependent scattering. The absolute value

G. de Vries; J. Bijvoet

1968-01-01

364

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

SciTech Connect

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

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

2011-05-01

365

Superconductivity in alkaline earth metal and Yb intercalated group VI layered dichalcogenides  

Microsoft Academic Search

Alkaline earth metals and Yb have been intercalated into Group VI layered dichalcogenides, e.g., MoS2, etc., by the liquid ammonia method at low temperatures. Chemical analysis and X-ray data indicate that ammonia is also intercalated along with the metal and that the c axis increases by ~3 Å in all the intercalated materials. In most cases, these compounds are only

G. V. Subba Rao; M. W. Shafer; S. Kawarazaki; A. M. Toxen

1974-01-01

366

Recovery of rare metals from scrap of rare earth intermetallic material by chemical vapour transport  

Microsoft Academic Search

A dry process for recovery of rare metals from sludges of Sm2Co17, Nd2Fe14B and LaNi5 intermetallic compounds was investigated using chemical vapour transport along a given temperature gradient. Chlorine and aluminium chloride were used as a chlorinating agent and a transporting agent respectively, and the rare metal chlorides were chemically transported as vapour complexes, e.g. RAlnCl3+3n (R = rare earth),

Kuniaki Murase; Ken-ichi Machida; Gin-ya Adachi

1995-01-01

367

Removal of heavy metal ions from wastewaters: a review.  

PubMed

Heavy metal pollution has become one of the most serious environmental problems today. The treatment of heavy metals is of special concern due to their recalcitrance and persistence in the environment. In recent years, various methods for heavy metal removal from wastewater have been extensively studied. This paper reviews the current methods that have been used to treat heavy metal wastewater and evaluates these techniques. These technologies include chemical precipitation, ion-exchange, adsorption, membrane filtration, coagulation-flocculation, flotation and electrochemical methods. About 185 published studies (1988-2010) are reviewed in this paper. It is evident from the literature survey articles that ion-exchange, adsorption and membrane filtration are the most frequently studied for the treatment of heavy metal wastewater. PMID:21138785

Fu, Fenglian; Wang, Qi

2010-12-08

368

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

369

Identification of condensed-phase species on the thermal transformation of alkaline and alkaline earth metal sulphates on a graphite platform  

NASA Astrophysics Data System (ADS)

Thermal treatment of alkaline and alkaline earth metal sulphates on a graphite platform was performed over the temperature range 200-2000 °C. The solid residues produced at each temperature were located by scanning electron microscopy (SEM) and then identified by energy-dispersive (ED) X-ray spectroscopy and Raman microanalysis. Additional experiments involved the dissolution of the residues from the platform and analysis by ion chromatography to determine the concentration of sulphate and other ions. A decomposition pattern was derived for the alkaline and alkaline earth metal sulphates. The transformation of the metal sulphates was dependent on temperature and the cation present. In general, the metal sulphates do not undergo significant decomposition to other species at temperatures less than 900 °C, with the exception of magnesium and beryllium sulphates, which are transformed into metal oxides to some extent. Above 900 °C, major transformations occur mainly for sodium, magnesium, and beryllium sulphates. For all the salts studied, there is evidence of the formation of species such as metal sulphides and elemental sulphur.

Castro, M. A.; Faulds, K.; Smith, W. E.; Aller, A. J.; Littlejohn, D.

2004-06-01

370

Fabrication by H+ or He+ ion implantation in lithium niobates and tantalates doped with rare earths and optical characterization  

Microsoft Academic Search

By using a Van de Graaff accelerator, optical waveguides are fabricated in rare earth ions-doped LiNbO3, LiNbO3 (MgO) and LiTaO3 crystals, by thermally controlled He+ or H+ implantation. The Rare earth ions used as dopants are either the Nd3+ laser ion or the Eu3+ structural probe. The mode spectra of the various waveguides are investigated by dark lines spectroscopy. The

C. Mignotte; P. Moretti; K. E. Lipinska-Kalita; G. Boulon; J. Mugnier

1996-01-01

371

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

SciTech Connect

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

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

1995-10-20

372

Angular Resolved Energy Analysis of (69)Ga+ Ions from a Gallium Liquid Metal Ion Source.  

National Technical Information Service (NTIS)

An analysis system was designed and built to characterize liquid metal ion source beams. Both mass and angular resolved energy distribution measurments can be made, from which both FWHM energy spreads and energy deficits can be obtained, thus making this ...

P. Marriott

1987-01-01

373

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

Microsoft Academic Search

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

D. Merten; E. Kothe; G. Büchel

2004-01-01

374

Structural modifications in biosynthetic melanins induced by metal ions.  

PubMed

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

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

1988-02-17

375

Colored thin films for specific metal ion detection.  

PubMed

This paper describes the investigation of chitosan and poly(allylamine) (PAH) for the creation of a multi-film, color-based dipstick for the detection of metal ions in solution. Thin, colored films of chitosan and PAH cross-linked with hexamethylene 1,6-di(aminocarboxysulfonate) (HDACS) are created where color is due to film thickness and optical interference effects. The films are investigated for their ability to selectively detect aqueous metal ions via changes in thickness and/or color. Chitosan-HDACS films were selective for Cr(VI) over all other metal ions tested including Cr(acac)3 and Cr(NO3)3 x 9H2O, and PAH-HDACS films were selective for Cu(II) and Cu(I) salts over all other metal ions tested. The irreversible, selective changes due to metal ion solutions were not caused by varying the pH. Potomac River water was also tested using the two films, with results indicating the presence of Cu(II) in the aqueous sample. PMID:15382871

Schauer, Caroline L; Chen, Mu-San; Price, Ronald R; Schoen, Paul E; Ligler, Frances S

2004-08-15

376

Rare earth–transition metal–magnesium compounds—An overview  

Microsoft Academic Search

Intermetallic rare earth–transition metal–magnesium compounds play an important role as precipitations in modern light weight alloys and as host materials for hydrogen storage applications. Recent results on the crystal chemistry, the chemical bonding peculiarities, physical properties, and hydrogenation behavior of these materials are reviewed.

Ute Ch. Rodewald; Bernard Chevalier; Rainer Poettgen

2007-01-01

377

Anisotropic thermal conductivity of rare earth--transition metal thin films  

Microsoft Academic Search

Thermal conductivity measurements were performed on several amorphous rare earth transition metal thin films of varying microstructure. The thermal conductivity perpendicular to the plane of the film, measured by the thermal comparator method, was compared with the thermal conductivity value measured parallel to the plane of the film. The latter value was obtained by converting electrical conductivity values to thermal

L. J. Shaw-Klein; T. K. Hatwar; S. J. Burns; S. D. Jacobs; J. C. Lambropoulos

1992-01-01

378

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

SciTech Connect

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

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

1986-04-01

379

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

Microsoft Academic Search

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

L. S. Strugach; M. I. Kuzmenkov; N. M. Sergeeva; A. I. Soklakov

1986-01-01

380

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

Microsoft Academic Search

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

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

2000-01-01

381

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

Microsoft Academic Search

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

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

1993-01-01

382

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

Microsoft Academic Search

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

Wangyu Hu; Huiqiu Deng; Xiaojian Yuan; Masahiro Fukumoto

2003-01-01

383

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

Microsoft Academic Search

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

T. Kaplan

1961-01-01

384

Energy position of 4f levels in rare-earth metals  

Microsoft Academic Search

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

Börje Johansson

1979-01-01

385

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

Microsoft Academic Search

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

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

2001-01-01

386

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

Microsoft Academic Search

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

Gamal A. M. Hussein

1996-01-01

387

Compounds of the Rare-Earth Metals with Aluminum and Their Crystalline Structures.  

National Technical Information Service (NTIS)

The data of the investigation and of the existing literature allow certain conclusions to be made about the compositions of compounds of the rare-earth metals with aluminum. While the compounds RAl2 of the MgCu2 type exist in all systems, the compositions...

P. I. Kripyakevich I. I. Zalutskii

1966-01-01

388

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

SciTech Connect

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

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

1980-06-01

389

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

SciTech Connect

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

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

1986-12-01

390

Activation energy for alkaline-earth ion transport in low alkali aluminoborosilicate glasses  

NASA Astrophysics Data System (ADS)

Activation energies (Ea) for ionic conduction in low-alkali boroaluminosilicate glasses due to alkaline-earth (Ba, Ca) and alkali (Na) ion transport have been estimated using thermally stimulated depolarization current (TSDC) and AC impedance spectroscopy techniques. The TSDC plot showed distinct relaxation peaks which shifted to higher temperatures with increasing ramp rates, and the dielectric dispersion plot showed individual low frequency relaxation peaks indicating space charge polarization due to transport of cations with different Ea (0.93, 1.83, and 3.5 eV for Na, Ba, and Ca, respectively). The higher value of Ea for Ca transport is attributed to mixed alkaline earth effect.

Dash, Priyanka; Furman, Eugene; Pantano, Carlo G.; Lanagan, Michael T.

2013-02-01

391

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

392

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

NASA Astrophysics Data System (ADS)

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

Sahin, H.; Peeters, F. M.

2013-02-01

393

Genuine redox isomerism in a rare-earth-metal complex.  

PubMed

Redox isomerism is observed for a lanthanide complex for the first time. Upon lowering the temperature, an electron of [{(dpp-bian)Yb(?-Cl)(dme)}(2)] (1) is transferred from the metal to the ligand (see picture), giving rise to marked shortening of Yb-N bonds and a hysteretic jump in the magnetic moment. The crystal packing is of a crucial importance, as two other crystal modifications of 1 do not undergo this effect. PMID:22991254

Fedushkin, Igor L; Maslova, Olga V; Morozov, Alexander G; Dechert, Sebastian; Demeshko, Serhiy; Meyer, Franc

2012-09-18

394

Quadrupole resonances in the rare-earth metals  

SciTech Connect

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

Liberman, D.; Zangwill, A.

1989-01-01

395

Rare earth metal oxazoline complexes in asymmetric catalysis.  

PubMed

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

Ward, Benjamin D; Gade, Lutz H

2012-11-01

396

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

NASA Astrophysics Data System (ADS)

Simultaneous measurements of the small, intermediate and large positive ions and air-Earth current density made at a coastal station, Maitri (70°45'52?S, 11°44'03?E, 130 m above sea level), at Antarctica during January-February 2005, are reported. Although small and large positive ion concentrations do not show any systematic diurnal variations, variations in them are almost similar to each other. On the other hand, variations in intermediate positive ion concentrations are independent of variations in the small/large positive ions and exhibit a diurnal variation which is similar to that in atmospheric temperature on fair weather days with a maximum during the day and minimum during the night hours. No such diurnal variation in intermediate positive ion concentration is observed on cloudy days when variations in them are also similar to those in small/large positive ion concentrations. Magnitude of diurnal variation in intermediate positive ion concentration on fair weather days increases with the lowering of atmospheric temperature in this season. Scavenging of ions by snowfall and trapping of ?-rays from the ground radioactivity by a thin layer of snow on ground is demonstrated from observations. Variations in intermediate positive ion concentration are explained on the basis of the formation of new particles by the photolytic nucleation process.

Siingh, Devendraa; Pant, Vimlesh; Kamra, A. K.

2007-07-01

397

The free escape boundary of diffuse ions upstream of the Earth's quasi-parallel bow shock  

NASA Astrophysics Data System (ADS)

The Earth's bow shock is very efficient in accelerating ions out of the incident solar wind distribution to high energies (? 200 keV/e). Energetic ions accelerated at the quasi-parallel bow shock are also known as diffuse ions and are best represented by exponential spectra in energy/charge, which require additional assumptions to be incorporated into the models. One of these assumptions is a free escape boundary along the interplanetary magnetic field into the upstream direction. We use two years of data from the background monitor on the IBEX spacecraft, supported by ACE solar wind observations, to investigate the existence of an upstream free escape boundary for bow shock accelerated ions. The IBEX mission was launched into an 18000 km by 50 RE orbit with a 7.5 day period, which provides extended periods of time in the region upstream of the bow shock. The IBEX background monitor is sensitive to protons > 14 keV which includes the energy of the maximum flux for diffuse ions. With increasing distance from the bow shock along the interplanetary magnetic field, the background count rates from diffuse ions stay constant for ions streaming away from the bow shock while diffuse ion count rates streaming towards the shock decrease for distances > 10 - 15 RE. These observations appear to support the existence of a free escape boundary for ions > 14 keV at a distance of ~10 - 15 RE from the shock.

Trattner, K. J.; Allegrini, F.; Dayeh, M. A.; Funsten, H. O.; Fuselier, S. A.; Heirtzler, D.; Janzen, P. H.; Kucharek, H.; McComas, D. J.; Moebius, E.; Moore, T. E.; Petrinec, S. M.; Reisenfeld, D. B.; Schwadron, N. A.; Wurz, P.

2011-12-01

398

Liquid-metal ion source study of critical sizes of multiply charged positive ions  

Microsoft Academic Search

LPIS (liquid-metal ion source) results are presented on the critical size above which ions of a given charge state begin to be observed for a given element. Tin and copper are considered, and the critical-size value for copper is interpreted using a simple quantum-mechanical calculation in which the molecular ions are assumed to be compact. The hopping of electrons from

P. Joyes; J. van de Walle

1985-01-01

399

Observations of ion and electron velocity distributions associated with slow-mode shocks in Earth's distant magnetotail  

Microsoft Academic Search

Three-dimensional observations of ion and electron velocity distributions with the Geotail spacecraft for three crossings of slow-mode shocks encountered in Earth's distant magnetotail are presented. Important findings from the observations are (1) the ion velocity distributions in the shock layer and the downstream region of the shocks are highly anisotropic because of the presence of multiple ion components in velocity

J. Seon; L. A. Frank; W. R. Paterson; J. D. Scudder; F. V. Coroniti; S. Kokubun; T. Yamamoto

1996-01-01

400

Process for Removal of Heavy-Metal Ions from Waste Water (Japanese Patent).  

National Technical Information Service (NTIS)

A process for removal of heavy-metal ions from waste water is characterized by the fact that a waste water containing heavy-metal ions is brought into contact with active ferrite to adsorb the heavy-metal ions, followed by desorption of the heavy-metal io...

S. Goto T. Nagura

1983-01-01

401

Adsorbent for metal ions and method of making and using  

SciTech Connect

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

2000-07-25

402

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

403

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

404

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

405

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

406

Hf-W constraints on metal-silicate mixing during Earth accretion  

NASA Astrophysics Data System (ADS)

We revisit the problem of partial metal-silicate re-equilibration during core-mantle differentiation and its effect on Hf-W chronometry. Previous models have focalized on the possibility that only a fraction of the core of impacting bodies equilibrates with the Earth mantle, but it was generally assumed that this fraction of impactor cores equilibrated with the whole mantle. We relax this probably unrealistic assumption and consider incomplete re-equilibration of the mantle. We first study the effect of partial mantle re-equilibration on Hf-W chronometry in a continuous accretion model with exponentialy decreasing accretion rate. Partial mantle re-equilibration during accretion leads to higher ? W for a given accretion timescale, which imply that a longer accretion (possibly by several tens of My) is required to explain the 182W excess of the Bulk Silicate Earth (BSE). Alternatively, using estimates of the age of the Moon as a constraint on Earth's accretion timescale provides usefull bounds on the amount of metal-silicate mixing. If the metal phase is assumed to fully equilibrate, we find that it must have mixed and equilibrated with a volume of silicate more than 10 times larger in order to explain the 182W excess of the BSE. If the metal phase equilibrates partially, the amount of mixing required is even larger. From a dynamical point of view, this implies that dispersion of a significant fraction of the metallic phase in the mantle must have been the norm during Earth accretion. In order to avoid the arbitrary choice of a particular form of the accretion history, we perform Monte-Carlo simulations of accretion and evolution of Hf-W abundances. This generates an envelope for acceptable accretion curves, and provides bounds on the mean amount of metal-silicate mixing and equilibration during accretion.

Deguen, R.; Olson, P.

2011-12-01

407

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

408

Broad-beam multi-ampere metal ion source  

SciTech Connect

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

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

1989-06-01

409

What Happens to Serum Metal Ion Levels After a Metal-on-Metal Bearing is Removed?  

PubMed

Serum cobalt (Co) and chromium (Cr) levels are commonly used to screen for excessive wear of metal-on-metal hip replacements. However, it is unknown how rapidly these should decline after revision. 25 patients with average Co and Cr ion levels of 56.3?g/L and 20.5?g/L were followed with serial ion level testing post-revision. Over the first 6weeks post-revision, the rate of decline for Co and Cr was approximately 2% per day and this slowed to approximately 1% decline per day over the ensuing 6weeks. This translated to a decline of approximately 80% from the starting value after 6weeks and a decline of approximately 90% after 12weeks post-revision. The rate of decline for both Co and Cr was significantly faster during the first 6weeks (P<0.001). In patients with ultra-high Cr levels>20?g/L, the rate of Cr decline is less predictable and may be protracted leading to persistent elevation above 5?g/L for one year or more post-revision in some cases. PMID:23948123

Ball, Scott T; Severns, Dustyn; Linn, Michael; Meyer, R Scott; Swenson, F Craig

2013-08-12

410

Improved scales for metal ion softness and toxicity.  

PubMed

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

Kinraide, Thomas B

2008-11-03

411

Adsorption of Metal Ions and Metal Complexes on Clay Minerals: A Study of the Nature of Bonding by X-Ray Photoelectron Spectroscopy.  

National Technical Information Service (NTIS)

Results are reported of an investigation of the interaction of metal ions, metal ion complexes, and organic ligands with mineral and metal ion-saturated surfaces. Minerals studied include those with oxidizing and nonoxidizing surfaces (for example, lead, ...

J. G. Dillard A. B. Emerson M. H. Koppelman D. L. Crowther C. V. Schenck

1982-01-01

412

High pressure phase transitions in the rare earth metal erbium to 151 GPa  

NASA Astrophysics Data System (ADS)

High pressure x-ray diffraction studies have been performed on the heavy rare earth metal erbium (Er) in a diamond anvil cell at room temperature to a pressure of 151 GPa and Er has been compressed to 40% of its initial volume. The rare earth crystal structure sequence {hcp} \\to {Sm}~ {type} \\to {dhcp} \\to {distorted} fcc (hcp: hexagonal close packed; fcc: face centered cubic; dhcp: double hcp) is observed in Er below 58 GPa. We have carried out Rietveld refinement of crystal structures in the pressure range between 58 GPa and 151 GPa. We have examined various crystal structures that have been proposed for the distorted fcc (dfcc) phase and the post-dfcc phase in rare earth metals. We find that the hexagonal hR 24 structure is the best fit between 58 and 118 GPa. Above 118 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.9%. We have also established a clear trend for the pressure at which a post-dfcc phase is formed in rare earth metals and show that there is a monotonic increase in this pressure with the filling of 4f shell.

Samudrala, Gopi K.; Thomas, Sarah A.; Montgomery, Jeffrey M.; Vohra, Yogesh K.

2011-08-01

413

High pressure phase transitions in the rare earth metal erbium to 151 GPa.  

PubMed

High pressure x-ray diffraction studies have been performed on the heavy rare earth metal erbium (Er) in a diamond anvil cell at room temperature to a pressure of 151 GPa and Er has been compressed to 40% of its initial volume. The rare earth crystal structure sequence hcp ? Sm type ? dhcp ? distorted fcc (hcp: hexagonal close packed; fcc: face centered cubic; dhcp: double hcp) is observed in Er below 58 GPa. We have carried out Rietveld refinement of crystal structures in the pressure range between 58 GPa and 151 GPa. We have examined various crystal structures that have been proposed for the distorted fcc (dfcc) phase and the post-dfcc phase in rare earth metals. We find that the hexagonal hR 24 structure is the best fit between 58 and 118 GPa. Above 118 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.9%. We have also established a clear trend for the pressure at which a post-dfcc phase is formed in rare earth metals and show that there is a monotonic increase in this pressure with the filling of 4f shell. PMID:21753243

Samudrala, Gopi K; Thomas, Sarah A; Montgomery, Jeffrey M; Vohra, Yogesh K

2011-07-14

414

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

2010-05-31

415

Crystal-field interactions and magnetism in rare-earth transition-metal intermetallic compounds  

Microsoft Academic Search

The description of basic experiments of the rare-earth hard magnetic materials, high-field magnetization curves on single-crystalline samples of Ho2Co17 and Nd2Fe14B is reviewed with the aim to derive parameters physically relevant on atomic scale. The anisotropic magnetic properties have been found to be of single-ion origin. The successful description of the rare-earth compounds Ho2Co17, Nd2Fe14B, Pr2Fe14B, ErNi5, PrRu2Si2, ErRu2Si2 in

R. J Radwanski; R. Michalski; Z. Ropka; A. Blaut

2002-01-01

416

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

417

Earth  

NSDL National Science Digital Library

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Earth. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions show Earth features such as the Ross Ice Shelf in Antarctica, Simpson Desert in Australia, Mt. Etna in Sicily, the Cassiar Mountains in Canada, the Strait of Gibraltar, Mississippi River, Grand Canyon, Wadi Kufra Oasis in Libya, and Moon images such as Hadley Rille, Plum Crater, massifs and Moon rocks. These images were taken with the Galileo Spacecraft and by the Apollo missions.

418

Optical characterization of some rare earth ions doped bismuth borate glasses and effect of gamma irradiation  

NASA Astrophysics Data System (ADS)

Rare earth doped bismuth borate glasses were prepared by conventional melt annealing method. The density, molar volume, ultraviolet, visible, and infrared spectroscopic and optical energy band gap of these glasses have been measured or calculated and employed to investigate the prepared glassy samples. The refractive index and molar refraction have been calculated using the theory of reflectively of light. The luminescence properties of the glasses were analyzed. The undoped glass shows strong extended UV-near visible absorption bands which are attributed to the collective presence of both trace iron impurities from raw materials and also the sharing of bismuth Bi+3 ions. The rare earth doped samples show the same strong UV-near visible bands as the undoped sample beside extra characteristic bands due to the respective rare earth ions. Results showed that the luminescence intensity changed with different rare earth oxides. The decreasing values of optical band gap and band tail can be understood and related in terms of the structural changes that are taking place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate network (BO3, BO4 groups) together with vibrational modes due to Bi-O groups. The IR spectra are slightly affected by gamma irradiation indicating the stability of the structural glassy forming units. The prepared samples reveal varying responses towards the effect of gamma irradiation.

Marzouk, M. A.

2012-07-01

419

Excited state absorption in glasses activated with rare earth ions: Experiment and modeling  

NASA Astrophysics Data System (ADS)

We present semiempirical approach based on the Judd-Ofelt theory and apply it for modeling the spectral properties of fluoride glasses activated with the rare earth (RE) ions. This method provide a powerful tool for simulating both ground state absorption (GSA) and excited state absorption (ESA) spectra of RE ions, e.g. Nd3+, Ho3+, Er3+ and Tm3+ in the ZBLAN glass matrix. The results of theoretical calculations correspond to the experimentally measured data. We also demonstrate that the spectra obtained using the presented approach are applicable in the analysis of up-conversion excitation schemes in these optoelectronically relevant materials.

Piatkowski, Dawid; Mackowski, Sebastian

2012-10-01

420

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

SciTech Connect

The relationship between the isotope fractionation of alkaline-earth elements in the surface ionization ion source and the evaporation filament current, i.e., filament temperature, was studied. It was confirmed that the isotope fractionation depends on the evaporation filament temperature; the isotope fractionation in the case of higher temperature of filament becomes larger. The ionization and evaporation process in the surface ionization ion source was discussed, and it was concluded that the isotope fractionation is suppressed by setting at the lower temperature of evaporation filament because the dissociations are inhibited on the evaporation filament.

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

2012-02-15

421

Heavy metal ions are potent inhibitors of protein folding  

SciTech Connect

Environmental and occupational exposure to heavy metals such as cadmium, mercury and lead results in severe health hazards including prenatal and developmental defects. The deleterious effects of heavy metal ions have hitherto been attributed to their interactions with specific, particularly susceptible native proteins. Here, we report an as yet undescribed mode of heavy metal toxicity. Cd{sup 2+}, Hg{sup 2+} and Pb{sup 2+} proved to inhibit very efficiently the spontaneous refolding of chemically denatured proteins by forming high-affinity multidentate complexes with thiol and other functional groups (IC{sub 50} in the nanomolar range). With similar efficacy, the heavy metal ions inhibited the chaperone-assisted refolding of chemically denatured and heat-denatured proteins. Thus, the toxic effects of heavy metal ions may result as well from their interaction with the more readily accessible functional groups of proteins in nascent and other non-native form. The toxic scope of heavy metals seems to be substantially larger than assumed so far.

Sharma, Sandeep K. [Biochemisches Institut, Universitaet Zuerich, CH-8057 Zuerich (Switzerland); Departement de Biologie Moleculaire Vegetale, Universite de Lausanne, CH-1015 Lausanne (Switzerland); Goloubinoff, Pierre [Departement de Biologie Moleculaire Vegetale, Universite de Lausanne, CH-1015 Lausanne (Switzerland); Christen, Philipp [Biochemisches Institut, Universitaet Zuerich, CH-8057 Zuerich (Switzerland)], E-mail: christen@bioc.uzh.ch

2008-07-25

422

Determination of rare-earth elements in coal using microwave digestion and gradient ion chromatography  

Microsoft Academic Search

The combined application of microwave digestion, high-performance ion chromatography (HPIC) and on-line sample solution concentration provides a technique for the routine determination of rare-earth elements (REE) in coals. Acid dissolution of whole powdered coal samples using microwave pressure digestion removes the necessity of dry ashing to eliminate organic carbon, providing considerable time savings and significantly reducing the risk of sample

Ronald T. Watkins; Moira K. Ridley; M. A. Bruno Pougnet; James P. Willis

1995-01-01

423

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

Microsoft Academic Search

Simultaneous measurements of the small-, intermediate- and large- positive\\u000aions and air earth current density made at a coastal station, Maitri at\\u000aAntarctica during January to February 2005, are reported. Although, small and\\u000alarge positive ion concentrations do not show any systematic diurnal\\u000avariations, variations in them are almost similar to each other. On the other\\u000ahand, variations in intermediate

Vimlesh Pant; A. K. Kamra

2009-01-01

424

Ternary rare earth and actinoid transition metal carbides viewed as carbometalates  

SciTech Connect

Ternary carbides A{sub x}T{sub y}C{sub z} (A=rare earth metals and actinoids; T=transition metals) with monoatomic species C{sup 4-} as structural entities are classified according to the criteria (i) metal to carbon ratio, (ii) coordination number of the transition metal by carbon atoms, and (iii) the dimensionality of the anionic network [T{sub y}C{sub z}]{sup n-}. Two groups are clearly distinguishable, depending on the metal to carbon ratio. Those where this ratio is equal to or smaller than 2 may be viewed as carbometalates, thus extending the sequence of complex anions from fluoro-, oxo-, and nitridometalates to carbometalates. The second group, metal-rich carbides with metal to carbon ratios equal to or larger than 4 is better viewed as typical intermetallics (''interstitial carbides''). The chemical bonding properties have been investigated by analyzing the Crystal Orbital Hamilton Population (COHP). The chemical bonding situation with respect to individual T-C bonds is similar in both classes. The main difference is the larger number of metal-metal bonds in the crystal structures of the metal-rich carbides.

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

2007-02-15

425

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

PubMed

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 constants of the resulting complexes ML, MHL, M(2)L and M(2)HL were determined. The stabilities of both ML and M(2)L complexes were found to vary in the order Mg(2+)> Ca(2+)> Sr(2+)> Ba(2+). Studying the complex formation between Al(3+) ion (M) and XO (L), it was observed that four complexed species with stoichiometries ML, ML(2), MHL and MH(2)L could be formed in solution. It was also found that the Al L(2) complex can act as a chelating agent for further complexation with two cations other than Al(3+) ion (i.e. Ba, L, Al, L, Ba, Mg, L, Al, L, Mg, and Mg, L, Al, L, Ba). The formation constants of the resulting mixed complexes were determined and their distribution diagrams were investigated. PMID:18967209

Gholivand, M B; Bamdad, F; Ghasemi, J

1998-08-01

426

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

SciTech Connect

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

Kondo, Kazuo; Sumi, Hisaharu; Matsumoto, Michiaki [Doshisha Univ., Tanabe, Kyoto (Japan)

1996-07-01

427

Polyols as scaffolds in the development of ion-selective polymer-supported reagents: the effect of auxiliary groups on the mechanism of metal ion complexation.  

PubMed

In developing ion-selective polymer-supported reagents, the inherent affinity of a given ligand for a targeted metal ion is found to be affected by auxiliary groups on a scaffold. A series of polyols (ethylene glycol, glycerol, tris(hydroxymethyl)ethane, pentaerythritol, and pentaerythritol triethoxylate) are immobilized onto cross-linked poly(vinylbenzyl chloride), then monophosphorylated. The pentaerythritol, glycerol, and pentaerythritol triethoxylate polymers have the highest affinities for both trivalent and divalent ions. The distribution coefficients of divalent ions (Pb(II), Cd(II), Cu(II), Ni(II), and Zn(II)) correlate with the Misono softness parameter, reflecting a single-site interaction between the metal ion and the phosphoryl oxygen. The distribution coefficients for trivalent ions are in the order Fe(III) < Al(III) < Y(III) less, approximately < La(III) approximately Eu(III) approximately Lu(III). For example, the phosphorylated pentaerythritol polymer has distribution coefficients (also reported as percent complexed) for Fe of 68.4 (75.3%); for Al of 182 (88.5%); and for the rare earth ions Y, Lu, Eu, and La of 374 (94.4%), 1390 (98.4%), 1690 (98.4%), and 708 (96.9%), respectively, from solutions at pH 2.0. The opposite trend (i.e., Fe(III) > Al(III) > (rare earths)) correlates with their hardness, acidity, electron affinity, electronegativity, and formation constants with soluble complexants, including tributyl phosphate. A binding mechanism is proposed wherein the polymer initially has the auxiliary -OH groups hydrogen-bonded to the phosphate ligand; then, binding to the polarizable phosphoryl oxygen with the divalent ions dominates, while the trivalent ions are drawn closer to the phosphoryl oxygen because of their greater charge and, once closer, bind in a multisite interaction with both the phosphate and -OH groups. PMID:18269222

Alexandratos, Spiro D; Zhu, Xiaoping

2008-02-12

428

Low-field mobilities of rare-earth metals  

NASA Astrophysics Data System (ADS)

In this paper, a dedicated ion mobility spectrometer for heavy element research will be presented. Like most advanced mobility spectrometers, the presented apparatus is equipped with a mass spectrometer for isotope-selective detection. In addition, the sample atoms are ionized by exploiting the element-selective laser resonance ionization techniques. First systematic studies at various lanthanide elements have shown that their low-field mobilities in argon are quite similar. The only exception is the element gadolinium, which exhibited an 8% lower reduced mobility of 1.692(24) cm2/V s. This anomaly is assumed to be a direct consequence of occupying the d- instead of an f-orbital in singly charged gadolinium, which in turn has a significant impact on the gadolinium-argon interaction potential.

Laatiaoui, M.; Backe, H.; Habs, D.; Kunz, P.; Lauth, W.; Sewtz, M.

2012-09-01

429

Ions originating from the Moon surface / exosphere observed in the Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

MAgnetic field and Plasma experiment - Plasma energy Angle and Composition Experiment (MAP-PACE) on Kaguya (SELENE) measured lunar plasmas in a polar orbit with an altitude of 100km, 50km, and in an elliptical orbit with perilune altitude as low as 10km. When Kaguya stayed in the Earth's magnetosphere, one of the MAP-PACE sensors IMA (Ion Mass Analyzer) detected ions from the Moon surface [Tanaka et al., GRL 36, L22106, 2009]. These ions were observed when the Moon was in the magnetospheric lobe, on the dayside of the Moon, especially when the solar zenith angle was below 40 degrees. IMA detected peaks for the heavy ions including C+, O+, Na+, K+, and Ar+ that indicated that these ions were originating from the Moon surface / exosphere. When these ions were discovered, they were considered to be accelerated by the potential difference between the lunar surface and Kaguya. Both the lunar surface and Kaguya were positively charged on the dayside of the Moon since photoelectron and electron currents are the major current sources and the photoelectron current dominates the current balance. Since the Debye length was larger than the spacecraft and much smaller than the Moon, it might be possible for the Moon surface to be positively charged to a higher potential than Kaguya. However, the recent detailed study on the ion flow direction with respect to the magnetic field revealed that the ion flow direction was mostly perpendicular to the magnetic field. It suggests that these ions were mostly accelerated by the convection electric field in the Earth's magnetotail. This hypothesis was proved by investigating an example that lobe cold ions were detected by another MAP-PACE ion sensor IEA while ions originating from the Moon surface / exosphere were detected by IMA. The ions originating from the Moon surface / exosphere also showed characteristic variation of the flux intensity that presumably related with the lunar surface structure or composition. Understanding the lunar plasmas will contribute to our understanding of the interaction between solar wind / magnetosphere and numerous non-magnetized airless bodies.

Saito, Y.; Yokota, S.; Nishino, M. N.; Yamamoto, T.; Uemura, K.; Tsunakawa, H.

2012-04-01

430

Iron atoms and metallic species in the Earth's upper atmosphere  

SciTech Connect

Resonant lidar detection of iron atoms have been performed at the Observatoire de Haute Provence (France) during 4 nights in November 1986 and in April 1987. The average iron atoms abundance is 3.6 x 10{sup 9} cm{sup {minus}2} in November, and 2.6 x 10{sup 9{minus}} cm{sup {minus}2} in April. Iron atoms density profiles are compared to the atomic sodium ones, obtained simultaneously by lidar and indicating an average sodium abundance of 4 x 10{sup 9} cm{sup {minus}2}. The relative abundance of the sum of the atomic and ionic forms is compared for several metallic species with their abundance ratios in the incoming meteorites. Finally, similar comparisons using lidar and mass spectrometer data are made for the ratio of the atomic and the ionic forms in the atmosphere.

Granier, C.; Jegou, J.P.; Megie, G. (CNRS Verrieres le Buisson (France))

1989-03-01

431

Optical detection of a single rare-earth ion in a crystal  

NASA Astrophysics Data System (ADS)

Rare-earth-doped laser materials show strong prospects for quantum information storage and processing, as well as for biological imaging, due to their high-Q 4f?4f optical transitions. However, the inability to optically detect single rare-earth dopants has prevented these materials from reaching their full potential. Here we detect a single photostable Pr3+ ion in yttrium aluminium garnet nanocrystals with high contrast photon antibunching by using optical upconversion of the excited state population of the 4f?4f optical transition into ultraviolet fluorescence. We also demonstrate on-demand creation of Pr3+ ions in a bulk yttrium aluminium garnet crystal by patterned ion implantation. Finally, we show generation of local nanophotonic structures and cell death due to photochemical effects caused by upconverted ultraviolet fluorescence of praseodymium-doped yttrium aluminium garnet in the surrounding environment. Our study demonstrates versatile use of rare-earth atomic-size ultraviolet emitters for nanoengineering and biotechnological applications.

Kolesov, R.; Xia, K.; Reuter, R.; Stöhr, R.; Zappe, A.; Meijer, J.; Hemmer, P. R.; Wrachtrup, J.

2012-08-01

432

The ligand-promoted mobilisation of metal ions from mineral surfaces  

NASA Astrophysics Data System (ADS)

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

Putnis, C. V.

2003-04-01

433

Cross-sensitive rare-earth metal sensors based on bidentate neutral organophosphorus compounds and chlorinated cobalt dicarbollide.  

PubMed

A variety of new chemical sensors (ion selective electrodes) for determination of rare-earth (RE) and trivalent metal cations such as yttrium(III), lanthanum(III), praseodymium(III), neodymium(III) and europium(III) that are commonly present in aqueous radiological samples, e.g. in high-level liquid waste (HLW) and solutions from reprocessing spent nuclear fuel, have been developed and studied. The sensors are based on bidentate neutral organophosphorus compounds, such as methylene bridged diphosphine dioxides and carbamoylmethylphosphine oxides, which are efficient extractants, especially when used in conjunction with chlorinated cobalt dicarbollide, for recovery and concentration of the RE and actinide elements from acidic HLW derived from the nuclear fuel cycle. The sensors exhibit remarkable sensitivity to RE cations and indicate promise for HLW analysis. PMID:17723484

Legin, A V; Kirsanov, D O; Babain, V A; Borovoy, A V; Herbst, R S

2006-05-27

434

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

435

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

436

Proteins and protein-rich biomass as environmentally friendly adsorbents selective for precious metal ions.  

PubMed

Proteins exhibit specific interactions with various metal ions, which play important roles in a living cell. Here, we found that various proteins selectively adsorbed precious metal ions at a wide range of pH values. Studies on protein sequences and on synthesized peptides revealed that a histidine-containing sequence had specific interactions with precious metal ions (Au3+ and Pd2+). We then investigated a few types of protein-rich biomass as adsorbents for precious metal ions. In the presence of various transition metal ions, Au3+ and Pd2+ were also selectively adsorbed onto the biomass tested. The bound precious metal ions were recovered by aqua regia after charring the metal-bound biomass. Finally, we demonstrated the successful recovery of Au3+ and Pd2+ from a metal refining solution and a metal plating waste using the biomass. We propose an environmentally friendly recycling system for precious metal ions using protein-rich biomass. PMID:17593742

Maruyama, Tatsuo; Matsushita, Hironari; Shimada, Yukiko; Kamata, Ichiro; Hanaki, Misa; Sonokawa, Saori; Kamiya, Noriho; Goto, Masahiro

2007-02-15

437

Metal ion bombardment of onion skin cell wall  

SciTech Connect

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

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

2004-05-10

438

Exchange interaction in binuclear complexes with rare-earth and copper ions: A many-body model study  

Microsoft Academic Search

We have used a many-body model Hamiltonian to study the nature of the magnetic ground state of heterobinuclear complexes involving rare-earth and copper ions. We have taken into account all diagonal repulsions involving the rare-earth 4f and 5d orbitals and the copper 3d orbital. In addition, we have included direct exchange interaction, crystal field splitting of the rare-earth atomic levels

Indranil Rudra; C. Raghu; S. Ramasesha

2002-01-01

439

Enhanced superconductivity by rare-earth metal doping in phenanthrene  

NASA Astrophysics Data System (ADS)

We successfully synthesized La- and Sm-doped phenanthrene powder samples and observed superconductivity in them at Tc around 6 K. The Tcs are 6.1 K for La1 phenanthrene and 6.0 K for Sm1 phenanthrene, which are enhanced by about 1 and 0.5 K compared to those in A3 phenanthrene (A = K and Rb) and in Ae1.5 phenanthrene (Ae = Sr and Ba) superconductors, respectively. The superconductive shielding fractions for La1 phenanthrene and Sm1 phenanthrene are 46.1% and 49.8% at 2 K, respectively. The small effect of doping with the magnetic ion Sm3+ on Tc and the positive pressure dependence coefficient of Tc strongly suggest unconventional superconductivity in the doped phenanthrene superconductors. The charge transfer to organic molecules from dopants of La and Sm induces a redshift of 7 cm-1 per electron for the mode at 1441 cm-1 in the Raman spectra, which is almost the same as those observed in A3 phenanthrene (A = K and Rb) and Ae1.5 phenanthrene (Ae = Sr and Ba) superconductors.

Wang, X. F.; Luo, X. G.; Ying, J. J.; Xiang, Z. J.; Zhang, S. L.; Zhang, R. R.; Zhang, Y. H.; Yan, Y. J.; Wang, A. F.; Cheng, P.; Ye, G. J.; Chen, X. H.

2012-08-01

440

Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete  

DOEpatents

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

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

1983-05-13

441

ANION EXCHANGE SEPARATIONS OF METAL IONS IN PARTIALLY NONAQUEOUS SOLUTIONS  

Microsoft Academic Search

A systematic approach to anion exchange in partially nonaqueous solvents ; was initiated. Distribution coefficicients of metal ions for Dowex 1 X8, ; chloride form resin in organic solvent-water mixtures containing hydrochloric ; acid were measured. The organic solvents used were methyl alcohol, ethyl ; alcohol, isopropyl alcohol, acetone, and dioxane. When the organic solvent ; concentration was increased and

D. J. Pietrzyk; J. S. Fritz

1960-01-01

442

Electrostatic Force Microscopy of Metallic Ion-Intercalated DNA  

NASA Astrophysics Data System (ADS)

The local charge of plasmid DNA has been studied using electrostatic force microscopy (EFM). The sample was prepared by immersing plasmid DNA in ZnCl2. The interaction of the tip with the positive local charge was stronger for the DNA immersed in a solution of higher concentration, and this phenomenon was evidence of the positive metallic ion intercalation into DNA.

Jeon, Dongryul; Kim, Chaeho; Son, Jung Min; Lee, Nam Joo; Kang, Chi Jung; Kim, Yong-Sang

2006-01-01

443

Parameters influencing flotation in removal of metal ions  

Microsoft Academic Search

In this paper the main parameters affecting the flotation process, like reagents (collector, frother, flocculant, etc.) and feed concentrations, pH value of the solution, ionic strength, gas flowrate and bubbles size, as applied to the separation of heavy metals and from dilute aqueous solutions, hydro?metallurgical or environmental origin, are examined. The flotation methods used, in laboratory scale, were ion, precipitate

A. I. Zouboulis; K. A. Matis; G. A. Stalidis

1990-01-01

444

Accumulation of heavy-metal ions by Zoogloea ramigera  

Microsoft Academic Search

Biomass has been produced from glucose using the organism Zoogloea ramigera 115. This biomass has been used to remove copper, cadmium, and uranyl ions from water solutions. The metal uptake was studied with two different methods: either by spectrophotometric measurements on the solutions after flocculation or by potentiometric measurements with amalgam electrodes in order to follow the entire complex formation.

Anders B. Norberg; Hans Persson

1984-01-01

445

Carboxylation of scleroglucan for controlled crosslinking by heavy metal ions  

Microsoft Academic Search

Samples of carboxylated scleroglucan, sclerox, with a degree of carboxylation in the side-chains varying from 10 to 50% were made in order to investigate the potential of using carboxylation as a means to control subsequent gelation by heavy metal ions. The storage and loss moduli of aqueous solutions of sclerox samples as a function of time were determined at T

Bjørn T. Stokke; Arnljot Elgsaeter; Olav Smidsrød; Bjørn E. Christensen

1995-01-01

446

COAGULATION AND PRECIPITATION OF SELECTED METAL IONS FROM AQUEOUS SOLUTIONS  

EPA Science Inventory

The report gives results of laboratory jar tests to develop data on the removal from aqueous solution of 12 metal ions of environmental concern. The project, of very limited scope, provides initial screening data only: coagulants were evaluated at only two dose levels (1.1 and 1....

447

Ion Beam Mixing in Binary Amorphous Metallic Alloys.  

National Technical Information Service (NTIS)

Ion beam mixing (IM) was measured in homogeneous amorphous metallic alloys of Cu-Er and Ni-Ti as a function of temperature using tracer impurities, i.e., the so-called ''marker geometry''. In Cu-Er, a strong temperature dependence in IM was observed betwe...

H. Hahn R. S. Averback T. Diaz de la Rubia P. R. Okamoto

1985-01-01

448

Diane Oligomers: Heat Resistance Increase by Metal Ions  

Microsoft Academic Search

Examination has been made of the possibility of increasing the heat resistance of diane oligomers by means of the introduction of Cu, Co, or Ni ions into the polymer matrix. This was carried out by the hardening of epoxy oligomers with chelates of metals and aliphatic amines. The properties of polymers produced and their dependence on the quantity and structure

A. V. Kurnoskin

1991-01-01

449

Theory of electron spin resonance of magnetic ions in metals  

Microsoft Academic Search

Reviewed at both a relatively elementary and more advanced level is the interpretative theory of the electron spin resonance of magnetic ions in metals. The various theoretical possibilities are illustrated by experimental examples wherever possible. Initially the development is based upon the Bloch-Hasegawa equations. The relationship of the advanced theory to this more elementary theory is emphasized. Multimagnetic-impurity experiments, the

S. E. Barnes

1981-01-01

450

A rare-earth-magnet ion trap for confining low-Z, bare nuclei  

NASA Astrophysics Data System (ADS)

Simplifications in the theory for Rydberg states of hydrogenlike ions allow a substantial improvement in the accuracy of predicted levels, which can yield information on the values of fundamental constants and test theory if they can be compared with precision frequency measurements.[1] We consider the trapping of bare nuclei (fully-stripped) to be used in making Rydberg states of one-electron ions with atomic number 1< Z < 11. Numerical simulation is used here to study ion confinement in a compact, Penning-style ion trap consisting of electrodes integrated with rare-earth permanent magnets, and to model the capture of charge-state-selected ions extracted from an electron beam ion trap (EBIT). An experimental apparatus adapted to the NIST EBIT will also be discussed. Reference: [1] U.D. Jentschura, P.J. Mohr, J.N. Tan, and B.J. Wundt, ``Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions,'' Phys. Rev. Lett. 100, 160404 (2008).

Brewer, Samuel M.; Tan, Joseph N.

2009-05-01

451

Ion mobility studies of electronically excited states of atomic transition metal cations: Development of an ion mobility source for guided ion beam experiments  

Microsoft Academic Search

The design of an ion mobility source developed to couple to a guided ion beam tandem mass spectrometer is presented. In these\\u000a exploratory studies, metal ions are created continuously by electron ionization of the volatile hexacarbonyls of the three\\u000a group 6 transition metals. These ions are focused into a linear hexapole ion trap, which collects the ions and then creates

Christopher Iceman; Chad Rue; Robert M. Moision; Barun K. Chatterjee; P. B. Armentrout

2007-01-01

452

Precipitation of alkylbenzene sulfonates with metal ions  

SciTech Connect

The precipitation domains of P-(1-methylnonyl)benzene sulfonate ions with Li/sup +/, Na/sup +/, K/sup +/, Ca/sup 2 +/, Mg/sup 2 +/, Al/sup 3 +/, and La/sup 3 +/ and of Ca/sup 2 +/-P-(hexyloctyl)benzene sulfonate have been determined at constant pH and 25 C. The linear solubility boundaries reverse their slope at the critical micellar concentration of the surfactant. A semiquantitative interpretation of the data is offered. The properties of the solids formed also are described. 18 references.

Peacock, J.M.; Matijevic, E.

1980-10-01

453

Bulk and surface electronic structure of actinide, rare earth, and transition metal elements and compounds  

SciTech Connect

This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to study of unusual magnetic and structural properties of rare earth, actinide, and transition metals through high-precision electronic structure calculations. Magnetic moment anisotropies in bulk and surface systems were studied, with emphasis on novel surfaces with unusual magnetic properties with possible applicability in magnetic recording. The structural stability, bonding properties, and elastic response of the actinides, as well as transition and rare earth elements and compounds, were also studied. The project sought to understand the unusual crystallographic and cohesive properties of the actinides and the importance of correlation to structural stability and the nature of the delocalization transition in these elements. Theoretical photoemission spectra, including surface effects, were calculated for rare earths and actinides.

Wills, J.W.; Eriksson, O.

1996-07-01

454

Cyclometalative C-H bond activation in rare earth and actinide metal complexes.  

PubMed

Cyclometalative C-H bond activation is a process that is commonly encountered in the field of organometallic chemistry. In rare earth and actinide complexes, ligand cyclometalation is most prevalent in highly reactive alkyl and hydrido species. Numerous factors promote ligand cyclometalation and influence the rate at which it occurs. This tutorial review discusses key issues relevant to ligand cyclometalation in rare earth and actinide complexes, including kinetic and mechanistic considerations. A variety of examples is presented for a wide range of ligand types and metals, the scope of which is intended to include routine cases, while also highlighting exceptional cyclometalation reactions that lead to unusual bonding modes. The reaction chemistry of cyclometalated rare earth and actinide complexes with various small molecule substrates (e.g. phenol, anilines, triethylammonium salts, alkynes, olefins, hydrogen and hydrocarbons) is also outlined. PMID:23203155

Johnson, Kevin R D; Hayes, Paul G

2012-11-30

455

Quadrupole ion trap studies of the structure and reactivity of transition metal ion pair complexes  

PubMed

Ion pairs are common species observed in the electrospray mass spectra of transition metal coordination complexes. To understand the nature of these ion pairs, a systematic study of the gas-phase chemistry of these species using ion-molecule reactions and collision-induced dissociation (CID) was carried out. Ion pair complexes of the type MLnX+ (where M is Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II), L is 1,10-phenanthroline, 2,2'-bipyridine, ethylenediamine, diethylenetriamine or 1,4,8,11-tetraazacyclotetradecane and X is Cl-, NO3-, acetylacetonate, ClO4-, acetate or SCN-) were studied. Ion-molecule reactions can distinguish whether the counterion in an ion pair is an inner- or outer-sphere ligand and can determine the coordination mode of the counterion. In addition, CID and ion-molecule reactions reveal some interesting chemistry of these complexes and unique coordination modes for some of the anions studied here were inferred from the ion-molecule reactions. For example, the thiocyanate ion is found to coordinate in a bidentate fashion in Zn(II) and Ni(II) complexes, contrasting behavior typically observed in solution. Also, certain Co(II) and Fe(II) ion pair complexes undergo oxidation reactions in which species such as dioxygen and nitric oxide from the counterions ClO4- and NO3- are transferred to the Co(II) and Fe(II) complexes, showing the inherent affinity of these metals for these molecules. These complexes were also studied by ion-molecule reactions and CID. Dioxygen in complexes formed by CID is demonstrated to be bidentate, suggesting the formation of a peroxo ligand with concurrent oxidation of the metal. PMID:10767759

Vachet; Callahan

2000-03-01

456

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

SciTech Connect

This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was found that instrument interface design also plays a critical role in the cluster ion distribution seen in the mass spectrum. In Chapter 5, ESI-MS was used to investigate toxic metal binding to the [Gln{sup 11}]-amyloid {beta}-protein fragment (1-16). Pb and Cd bound stronger than Zn, even in the presence of excess Zn. Hg bound weaker than Zn. There are endless options for future work on cluster ions. Any molecule that is poorly ionized in positive ion mode can potentially show an increase in ionization efficiency if an appropriate anion is used to produce a net negative charge. It is possible that drug protein or drug/DNA complexes can also be stabilized by adding counter-ions. This would preserve the solution characteristics of the complex in the gas phase. Once in the gas phase, CID could determine the drug binding location on the biomolecule. There are many research projects regarding toxic metals in biology that have yet to be investigated or even discovered. This is an area of research with an almost endless future because of the changing dynamics of biological systems. What is deemed safe today may show toxic effects in the future. Evolutionary changes in protein structures may render them more susceptible to toxic metal binding. As the understanding of toxicity evolves, so does the demand for new toxic metal research. New instrumentation designs and software make it possible to perform research that could not be done in the past. What was undetectable yesterday will become routine tomorrow.

Nicholas B. Lentz

2007-12-01

457

Does metal ion complexation make radical clocks run fast?  

PubMed

Ab initio molecular orbital and density functional calculations at the CBS-RAD(QCISD,B3-LYP) level for Li+ and at B3LYP for Na+, K+, Cu+,and Ag+ reveal that the barrier to ring-closure of the 1-hexen-6-yl ("Delta(5)-hexenyl") radical to the cyclopentylmethyl radical, a so-called radical clock reaction, is decreased very significantly by complexation of the double bond to metal cations. This barrier lowering should occur on complexation with many metal ions, as shown by calculations on all of the monovalent ions listed above. Additional density functional calculations including explicit solvation of the model system complexed to the lithium ion with tetrahydrofuran suggest that the effect found is not limited to the gas phase but may also be significant in experimental radical clock reactions in solution, even for lithium. PMID:12603171

Horn, Anselm H C; Clark, Timothy

2003-03-01

458

Vibronic intensities in the electronic spectra of transition metal ions  

NASA Astrophysics Data System (ADS)

The electric dipole vibronic intensities due to the three odd parity vibrational modes of the 4A2g ? 4T1g(t2e) transition of the octahedral complex ion MnF62- have been evaluated using a combination of crystal field and ligand polarization methods. Several different force fields and radial functions have been employed. For the ligand polarization term, coupling of the induced ligand dipole to both the metal electric quadrupole and the electric hexadecapole are considered. Whilst the crystal field and these two ligand polarization contributions to the total vibronic intensity are all within a factor of ten, they each contribute to different vibronic origins. This shows that for this ion it is not sufficient to truncate the expansion of the metal ion electric multipole moment at the leading term.

Acevedo, R.; Flint, C. D.

459

Alkaline earth metal salts of 1-naphthoic acid.  

PubMed

The structures of the Mg, Ca, Sr and Ba salts of 1-naphthoic acid are examined and compared with analogous structures of salts of benzoate derivatives. It is shown that catena-poly[[[diaquabis(1-naphthoato-?O)magnesium(II)]-?-aqua] dihydrate], {[Mg(C(11)H(7)O(2))(2)(H(2)O)(3)]·2H(2)O}(n), exists as a one-dimensional coordination polymer that propagates only through Mg-OH(2)-Mg interactions along the crystallographic b direction. In contrast with related benzoate salts, the naphthalene systems are large enough to prevent inorganic chain-to-chain interactions, and thus species with inorganic channels rather than layers are formed. The Ca, Sr and Ba salts all have metal centres that lie on a twofold axis (Z' = 1/2) and all have the common name catena-poly[[diaquametal(II)]-bis(?-1-naphthoato)-?(3)O,O':O;?(3)O:O,O'], [M(C(11)H(7)O(2))(2)(H(2)O)(2)](n), where M = Ca, Sr or Ba. The Ca and Sr salts are essentially isostructural, and all three species form one-dimensional coordination polymers through a carboxylate group that forms three M-O bonds. The polymeric chains propagate via c-glide planes and through MOMO four-membered rings. Again, inorganic channel structures are formed rather than layered structures, and the three structures are similar to those found for Ca and Sr salicylates and other substituted benzoates. PMID:22850845

Arlin, Jean-Baptiste; Kennedy, Alan R

2012-07-19

460

Geospace Storms and Thermal Ions in the Near-Earth Magnetotail  

NASA Astrophysics Data System (ADS)

We will report on the conditions of thermal ions in the near-Earth magnetotail during geomagnetic storms and substorms. Using the Thermal Ion Dynamic Experiment (TIDE) measurements on the Polar spacecraft between the years of 2000 and 2005, we studied the plasma properties of thermal ions in the magnetotail at distances between 5 and 10 Earth radii as a function of solar wind conditions and geomagnetic activities. We merged over five years of high time resolution Polar/TIDE and MFE magnetic field, ACE solar wind plasma and magnetic field measurements, and geomagnetic AE, Kp and Dst indices when the Polar apogee was in the nightside. For comparison with ground observations, we use the Tsyganenko field model to map the spatial distributions of these plasma properties in the magnetospheric to the ionospheric altitudes, where the nightside auroral ovals in the northern and southern hemispheres are mostly mapped from these Polar distances. We will present statistical analyses of the spatial distributions of plasma properties of thermal ions at these altitudes and their relationships to upstream solar wind drivers and geomagnetic indices that are relevant to storm and substorm phenomena.

Chen, S.; Moore, T. E.

2006-05-01

461

Method for removing metal ions from solution with titanate sorbents  

SciTech Connect

A method for removing metal ions from solution comprises the steps of providing titanate particles by spray-drying a solution or slurry comprising sorbent titanates having a particle size up to 20 micrometers, optionally in the presence of polymer free of cellulose functionality as binder. The sorbent is active towards heavy metals from Periodic Table (CAS version) Groups IA, IIA, IB, IIB, IIIB, and VIII, to provide monodisperse, substantially spherical particles in a yield of at least 70% of theoretical yield which have a particle size distribution in the range of 1 to 500 micrometers. The particles can be used free flowing in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove metal ions from aqueous or organic liquid.

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

1999-11-23

462

Method for removing metal ions from solution with titanate sorbents  

DOEpatents

A method for removing metal ions from solution comprises the steps of providing titanate particles by spray-drying a solution or slurry comprising sorbent titanates having a particle size up to 20 micrometers, optionally in the presence of polymer free of cellulose functionality as binder, said sorbent being active towards heavy metals from Periodic Table (CAS version) Groups IA, IIA, IB, IIB, IIIB, and VIII, to provide monodisperse, substantially spherical particles in a yield of at least 70 percent of theoretical yield and having a particle size distribution in the range of 1 to 500 micrometers. The particles can be used free flowing in columns or beds, or entrapped in a nonwoven, fibrous web or matrix or a cast porous membrane, to selectively remove metal ions from aqueous or organic liquid.

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

1999-01-01

463

Dissociation of gas-phase dimeric complexes of lactic acid and transition-metal ions formed under electrospray ionization conditions; the role of reduction of the metal ion.  

PubMed

Dimeric complex ions of the type [M(A-H)A]+, where M=metal ion (Co, Ni, Cu, and Zn) and A=ligand (lactic acid, methyl lactate or ethyl lactate), were generated in the gas phase under electrospray ionization conditions. The collision-induced dissociation spectra of [M(A-H)A]+ ions were recorded to study the behaviour of ligand and metal ions in decomposition of these dimeric complex ions. Based on the fragmentation pathways observed for complex ions of lactic acid, it is found that both the carboxylic and hydroxyl groups of lactic acid are involved in the complex formation following displacement of a proton by the metal ion. The dimeric complex ions of Co, Ni, and Zn dissociated to yield similar types of ions, whereas that of Cu behaved differently. The dissociations of Co-, Ni-, and Zn-bound dimeric complexes involved losses of neutral molecules while keeping the oxidation state of the metal ion unchanged. However, elimination of radicals is found in the dissociation of dimeric complex ions of Cu, and the oxidation state of copper is reduced from Cu(II) to Cu(I) in the resulting fragment ions. The deprotonated ligand is involved in the fragmentation pathway of Cu complexes, whereas it is intact in other complexes. The oxidation state of the metal ion, nature of the ligand, and site of attachment to the metal ion are found to control the dissociation of these dimeric complex ions. PMID:15593065

Kumar, M Ravi; Prabhakar, S; Kumar, M Kiran; Reddy, T Jagadeshwar; Vairamani, M

2005-01-01

464

Metal-on-metal bearings total hip arthroplasty: the cobalt and chromium ions release concern.  

PubMed

With certain concerns recently reported on metal-on-metal bearing couples in total hip arthroplasty, this study's objective is to review the current knowledge concerning release of metal ions and its potential consequences. Each metal-on-metal implant presents different tribological properties. The analytical techniques for metals are accurate and the Co ion rates seem acceptable up to 2 ?g/L. A delayed type IV hypersensitivity reaction (atypical lymphocytic vasculitis-associated lesion [ALVAL]) may be the source of arthroplasty failure. Idiosyncratic, it remains unpredictable even using cutaneous tests and apparently is rare (0.3%). Today, there are no scientific or epidemiologic data supporting a risk of carcinogenesis or teratogenesis related to the use of a metal-on-metal bearings couple. Solid pseudotumors nearly exclusively are observed with resurfacing procedures, carrying a high annual revision rate in women under 40 years of age, occurring particularly in cases of acetabular malposition and with use of cast molded Cr-Co alloys. Osteolysis manifests through complete and progressive radiolucent lines or through cavitary lesions stemming from ALVAL-type alterations or impingement problems or implant incompatibility. The formation of wear debris exceeding the biological tolerance is possible with implant malposition, subluxation, and jamming of the femoral head in cases of cup deformity. Moreover, each implant presents different metal ion production; assessment of their performance and safety is required before their clinical use. With the knowledge available today, metal-on-metal bearing couples are contraindicated in cases of metal allergies or end stage renal dysfunction and small size resurfacing should cautiously be used. PMID:20832379

Delaunay, C; Petit, I; Learmonth, I D; Oger, P; Vendittoli, P A

2010-09-15

465

Chitosan removes toxic heavy metal ions from cigarette mainstream smoke  

NASA Astrophysics Data System (ADS)

This study investigated the removal of heavy metal ions from cigarette mainstream smoke using chitosan. Chitosan of various deacetylation degrees and molecular weights were manually added to cigarette filters in different dosages. The mainstream smoke particulate matter was collected by a Cambridge filter pad, digested by a microwave digestor, and then analyzed for contents of heavy metal ions, including As(III/V), Pb(II), Cd(II), Cr(III/VI) and Ni(II), by graphite furnace atomic absorption spectrometry (GFAAS). The results showed that chitosan had a removal effect