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1

Alkali metal ions through glass: a possible radioactive waste management application  

E-print Network

ALKALI METAL IONS THROUGH GLASS: A POSSIBLE RADIOACTIVE WASTE MANAGEMENT APPLICATION A Thesis by ROBERT ALLAN JONES Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1996 Major Subject: Health Physics ALKALI METAL IONS THROUGH GLASS: A POSSIBLE RADIOACTIVE WASTE MANAGEMENT APPLICATION A Thesis by ROBERT ALLAN JONES Submitted to Texas A&M University in partial fulfillment...

Jones, Robert Allan

1996-01-01

2

Development of materials for the removal of metal ions from radioactive and non-radioactive waste streams  

NASA Astrophysics Data System (ADS)

Nuclear wastes that were generated during cold-war era from various nuclear weapon programs are presently stored in hundreds of tanks across the United States. The composition of these wastes is rather complex containing both radionuclides and heavy metals, such as 137Cs, 90Sr, Al, Pb, Cr, and Cd. In this study, chitosan based biosorbents were prepared to adsorb some of these metal ions. Chitosan is a partially acetylated glucosamine biopolymer encountered in the cell walls of fungi. In its natural form this material is soft and has a tendency to agglomerate or form gels. Various methods were used to modify chitosan to avoid these problems. Chitosan is generally available commercially in the form of flakes. For use in an adsorption system, chitosan was made in the form of beads to reduce the pressure drop in an adsorption column. In this research, spherical beads were prepared by mixing chitosan with perlite and then by dropwise addition of the slurry mixture into a NaOH precipitation bath. Beads were characterized using Fourier Transform InfraRed Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS), Tunneling Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Thermogravimetric Analysis (TGA). The SEM, EDS, and TEM data indicated that the beads were porous in nature. The TGA data showed that bead contained about 32% chitosan. The surface area, pore volume, and porosity of the beads were determined from the BET surface area that was measured using N2 as adsorbate at 77K. Adsorption and desorption of Cr(VI), Cr(III), Cd(II), U(VI), Cu(II), from aqueous solutions of these metal ions were studied to evaluate the adsorption capacities of the beads for these metals ions. Equilibrium adsorption data of these metals on the beads were found to correlate well with the Langmuir isotherm equation. Chitosan coated perlite beads had negligible adsorption capacity for Sr(II) and Cs(I). It was found that Fullers earth had very good capacity for these two metals. However, the mechanical strength of Fullers earth granules available commercially was not sufficient for use in a column. In this study chitosan was used as a binder to make Fullers earth beads and were used for adsorption of Cs(I) and Sr(II). (Abstract shortened by UMI.)

Hasan, Md. Shameem

3

Charge Breeding of Radioactive Ions  

E-print Network

Charge breeding is a technique to increase the charge state of ions, in many cases radioactive ions. The singly charged radioactive ions, produced in an isotope separator on-line facility, and extracted with a low kinetic energy of some tens of keV, are injected into a charge breeder, where the charge state is increased to Q. The transformed ions are either directed towards a dedicated experiment requiring highly charged ions, or post-accelerated to higher beam energies. In this paper the physics processes involved in the production of highly charged ions will be introduced, and the injection and extraction beam parameters of the charge breeder defined. A description of the three main charge-breeding methods is given, namely: electron stripping in gas jet or foil; external ion injection into an electron-beam ion source/trap (EBIS/T); and external ion injection into an electron cyclotron resonance ion source (ECRIS). In addition, some preparatory devices for charge breeding and practical beam delivery aspects ...

Wenander, F J C

2013-01-01

4

RADIOACTIVE METAL MOBILIZATION  

Microsoft Academic Search

The potentialities, drawbacks, and limitations of ; ethylenediaminetetraacetic acid (EDTA) in the removal of radioaetive metals are ; discussed. The biological effectiveness of EDTA is compared with that of several ; other chelating agents, with emphasis on CaNaâ-diethylene-; triaminepentaacetic acid (DTPA). Data are tabulated on the effect of DTAA and ; EDTA on the retention of Y⁹¹, Ce¹⁴⁴, Th²³⁴, Pu\\/sup

Catsch

1961-01-01

5

Metal ion release from metal implants  

Microsoft Academic Search

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

T. Hanawa

2004-01-01

6

Method for decontamination of radioactive metal surfaces  

DOEpatents

Disclosed is a method for removing radioactive contaminants from metal surfaces by applying steam containing an inorganic acid and cerium IV. Cerium IV is applied to contaminated metal surfaces by introducing cerium IV in solution into a steam spray directed at contaminated metal surfaces. Cerium IV solution is converted to an essentially atomized or vapor phase by the steam.

Bray, L.A.

1996-08-13

7

Ion sources for radioactive beams  

SciTech Connect

The ion sources reviewed here, most of them developed for isotope separation on-line (ISOL), are classified according to their ionizing mechanism, utilizing electrons, heat, light, and penetration of matter. Emphasis is put on the beam-optical characteristics, ion current density, energy spread, and emittance on the ISOL-essentials {open_quotes}efficient, fast, and selective,{close_quotes} both for the ion source and the complete target/ion source-system.

Kirchner, R. [GSI Darmstadt (Germany)

1994-05-01

8

Radioactive scrap metal decontamination technology assessment report  

SciTech Connect

Within the DOE complex there exists a tremendous quantity of radioactive scrap metal. As an example, it is estimated that within the gaseous diffusion plants there exists in excess of 700,000 tons of contaminated stainless steel. At present, valuable material is being disposed of when it could be converted into a high quality product. Liquid metal processing represents a true recycling opportunity for this material. By applying the primary production processes towards the material`s decontamination and re-use, the value of the strategic resource is maintained while drastically reducing the volume of material in need of burial. Potential processes for the liquid metal decontamination of radioactively contaminated metal are discussed and contrasted. Opportunities and technology development issues are identified and discussed. The processes compared are: surface decontamination; size reduction, packaging and burial; melting technologies; electric arc melting; plasma arc centrifugal treatment; air induction melting; vacuum induction melting; and vacuum induction melting and electroslag remelting.

Buckentin, J.M.; Damkroger, B.K.; Schlienger, M.E. [Sandia National Labs., Albuquerque, NM (United States). Liquid Metal Processing Lab.

1996-04-01

9

A Novel Radioactive Isotope Ion Target SCRIT  

SciTech Connect

Electron scattering is a superior method to investigate the internal structure, such as charge distribution, of atomic nuclei. Most of the radii of nuclei were determined unambiguously by that. However, radioactive isotopes (RI) which recently came up to a major research interest have not been accessible due to the difficulty in making fixed targets and taking measurements before they decay. We proposed a conceptually new target called SCRIT (Self-Confining Radioactive Isotope ion Target) as opposed to a collider method. The luminosity expected for SCRIT is inevitably low (typically on the order of 1.E+27/cm{sup 2}/s) and a large acceptance detector system is required. We plan to perform a coincidence measurement using an electron arm and a recoil ion detector which needs to be developed. Current status of the ion trapping with a prototype SCRIT and the background measurement results in an electron storage ring will be discussed.

Kurita, Kazuyoshi [Department of Physics, Rikkyo University, Nishi-Ikebukuro Toshima, Tokyo, 171-8501 (Japan); Cycltron Center, RIKEN, Wako, Saitama, 351-0198 (Japan); Masuda, Tetsuya [Department of Physics, Rikkyo University, Nishi-Ikebukuro Toshima, Tokyo, 171-8501 (Japan); Koseki, Tadashi [Accelerator Division I, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Noda, Akira; Shirai, Toshiyuki; Tongu, Hiromu [Center for Beam Science, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 (Japan); Furukawa, Yukihiro; Tamae, Tadaaki [Laboratory of Nuclear Science, Tohoku University, Mikamine, Taihaku, Sendai, 982-0826 (Japan); Ito, Sachiko; Emoto, Takashi; Nakamura, Masato; Wakasugi, Masanori; Yano, Yasushige [Cycltron Center, RIKEN, Wako, Saitama, 351-0198 (Japan); Ohnishi, Tetsuya; Suda, Toshimi; Takeda, Hiroyuki; Wang Shuo [RI Beam Science Laboratory, RIKEN, Wako, Saitama, 351-0198 (Japan)

2006-11-20

10

Resonant Ionization Laser Ion Source for Radioactive Ion Beams  

SciTech Connect

A resonant ionization laser ion source based on all-solid-state, tunable Ti:Sapphire lasers is being developed for the production of pure radioactive ion beams. It consists of a hot-cavity ion source and three pulsed Ti:Sapphire lasers operating at a 10 kHz pulse repetition rate. Spectroscopic studies are being conducted to develop ionization schemes that lead to ionizing an excited atom through an auto-ionization or a Rydberg state for numerous elements of interest. Three-photon resonant ionization of 12 elements has been recently demonstrated. The overall efficiency of the laser ion source measured for some of these elements ranges from 1 to 40%. The results indicate that Ti:Sapphire lasers could be well suited for laser ion source applications. The time structures of the ions produced by the pulsed lasers are investigated. The information may help to improve the laser ion source performance.

Liu, Yuan [ORNL; Beene, James R [ORNL; Havener, Charles C [ORNL; Vane, C Randy [ORNL; Gottwald, T. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Wendt, K. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Mattolat, C. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Lassen, J. [TRIUMF, Canada

2009-01-01

11

BEARS: Radioactive Ion Beams at Berkeley  

SciTech Connect

A light-isotope radioactive ion beam capability has been added to the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory by coupling to the production cyclotron of the Berkeley Isotope Facility. The connection required the development and construction of a 350 m gas transport system between the two accelerators as well as automated cryogenic separation of the produced activity. The first beam developed, {sup 11}C, has been successfully accelerated with an on-target intensity of 1 x 10{sup 8} ions/sec at energies of around 10 MeV/u.

Powell, J.; Joosten, R.; Donahue, C.A.; Fairchild, R.F.; Fujisawa, J.; Guo, F.Q.; Haustein, P.E.; Larimer, R.-M.; Lyneis, C.M.; McMahan, M.A.; Moltz, D.M.; Norman, E.B.; O'Neil, J.P.; Ostas, M.A.; Rowe, M.W.; VanBrocklin, H.F.; Wutte, D.; Xie, Z.Q.; Xu, X.J.; Cerny, Joseph

2000-03-14

12

A radioactive ion beam facility using photofission  

Microsoft Academic Search

Use of a high-power electron linac as the driver accelerator for a Radioactive Ion Beam (RIB) facility is proposed. An electron beam of 30MeV and 100kW can produce nearly 5×1013 fissions\\/s from an optimized 235U target and about 60% of this from a natural uranium target. An electron beam can be readily transmitted through a thin window at the exit

William T Diamond

1999-01-01

13

BEARS: radioactive ion beams at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p, {alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88'' Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5x10{sup 7} ions/sec and {sup 14}O beams of 3x10{sup 5} ions/sec.

Powell, J.; Guo, F. Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.; Moltz, D. M.; Norman, E. B.; O'Neil, J. P.; Rowe, M. W.; VanBrocklin, H. F.; Xie, Z. Q.; Xu, X. J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Haustein, P. E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-21

14

BEARS: radioactive ion beams at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88{sup {double_prime}} Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88{sup {double_prime}} Cyclotron{close_quote}s Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p, {alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88{sup {double_prime}} Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5{times}10{sup 7}ions/sec and {sup 14}O beams of 3{times}10{sup 5}ions/sec. {copyright} {ital 1998 American Institute of Physics.}

Powell, J.; Guo, F.Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.; Moltz, D.M.; Norman, E.B.; O`Neil, J.P.; Rowe, M.W.; VanBrocklin, H.F.; Xie, Z.Q.; Xu, X.J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] Haustein, P.E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-01

15

Nuclear astrophysics with radioactive ions at FAIR  

E-print Network

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.

Reifarth, R; Göbel, K; Heftrich, T; Heil, M; Koloczek, A; Langer, C; Plag, R; Pohl, M; Sonnabend, K; Weigand, M; Adachi, T; Aksouh, F; Al-Khalili, J; AlGarawi, M; AlGhamdi, S; Alkhazov, G; Alkhomashi, N; Alvarez-Pol, H; Alvarez-Rodriguez, R; Andreev, V; Andrei, B; Atar, L; Aumann, T; Avdeichikov, V; Bacri, C; Bagchi, S; Barbieri, C; Beceiro, S; Beck, C; Beinrucker, C; Belier, G; Bemmerer, D; Bendel, M; Benlliure, J; Benzoni, G; Berjillos, R; Bertini, D; Bertulani, C; Bishop, S; Blasi, N; Bloch, T; Blumenfeld, Y; Bonaccorso, A; Boretzky, K; Botvina, A; Boudard, A; Boutachkov, P; Boztosun, I; Bracco, A; Brambilla, S; Monago, J Briz; Caamano, M; Caesar, C; Camera, F; Casarejos, E; Catford, W; Cederkall, J; Cederwall, B; Chartier, M; Chatillon, A; Cherciu, M; Chulkov, L; Coleman-Smith, P; Cortina-Gil, D; Crespi, F; Crespo, R; Cresswell, J; Csatlós, M; Déchery, F; Davids, B; Davinson, T; Derya, V; Detistov, P; Fernandez, P Diaz; DiJulio, D; Dmitry, S; Doré, D; nas, J Due\\; Dupont, E; Egelhof, P; Egorova, I; Elekes, Z; Enders, J; Endres, J; Ershov, S; Ershova, O; Fernandez-Dominguez, B; Fetisov, A; Fiori, E; Fomichev, A; Fonseca, M; Fraile, L; Freer, M; Friese, J; Borge, M G; Redondo, D Galaviz; Gannon, S; Garg, U; Gasparic, I; Gasques, L; Gastineau, B; Geissel, H; Gernhäuser, R; Ghosh, T; Gilbert, M; Glorius, J; Golubev, P; Gorshkov, A; Gourishetty, A; Grigorenko, L; Gulyas, J; Haiduc, M; Hammache, F; Harakeh, M; Hass, M; Heine, M; Hennig, A; Henriques, A; Herzberg, R; Holl, M; Ignatov, A; Ignatyuk, A; Ilieva, S; Ivanov, M; Iwasa, N; Jakobsson, B; Johansson, H; Jonson, B; Joshi, P; Junghans, A; Jurado, B; Körner, G; Kalantar, N; Kanungo, R; Kelic-Heil, A; Kezzar, K; Khan, E; Khanzadeev, A; Kiselev, O; Kogimtzis, M; Körper, D; Kräckmann, S; Kröll, T; Krücken, R; Krasznahorkay, A; Kratz, J; Kresan, D; Krings, T; Krumbholz, A; Krupko, S; Kulessa, R; Kumar, S; Kurz, N; Kuzmin, E; Labiche, M; Langanke, K; Lazarus, I; Bleis, T Le; Lederer, C; Lemasson, A; Lemmon, R; Liberati, V; Litvinov, Y; Löher, B; Herraiz, J Lopez; Münzenberg, G; Machado, J; Maev, E; Mahata, K; Mancusi, D; Marganiec, J; Perez, M Martinez; Marusov, V; Mengoni, D; Million, B; Morcelle, V; Moreno, O; Movsesyan, A; Nacher, E; Najafi, M; Nakamura, T; Naqvi, F; Nikolski, E; Nilsson, T; Nociforo, C; Nolan, P; Novatsky, B; Nyman, G; Ornelas, A; Palit, R; Pandit, S; Panin, V; Paradela, C; Parkar, V; Paschalis, S; Paw\\lowski, P; Perea, A; Pereira, J; Petrache, C; Petri, M; Pickstone, S; Pietralla, N; Pietri, S; Pivovarov, Y; Potlog, P; Prokofiev, A; Rastrepina, G; Rauscher, T; Ribeiro, G; Ricciardi, M; Richter, A; Rigollet, C; Riisager, K; Rios, A; Ritter, C; Frutos, T Rodríguez; Vignote, J Rodriguez; Röder, M; Romig, C; Rossi, D; Roussel-Chomaz, P; Rout, P; Roy, S; Söderström, P; Sarkar, M Saha; Sakuta, S; Salsac, M; Sampson, J; Saez, J Sanchez del Rio; Rosado, J Sanchez; Sanjari, S; Sarriguren, P; Sauerwein, A; Savran, D; Scheidenberger, C; Scheit, H; Schmidt, S; Schmitt, C; Schnorrenberger, L; Schrock, P; Schwengner, R; Seddon, D; Sherrill, B; Shrivastava, A; Sidorchuk, S; Silva, J; Simon, H; Simpson, E; Singh, P; Slobodan, D; Sohler, D; Spieker, M; Stach, D; Stan, E; Stanoiu, M; Stepantsov, S; Stevenson, P; Strieder, F; Stuhl, L; Suda, T; Sümmerer, K; Streicher, B; Taieb, J; Takechi, M; Tanihata, I; Taylor, J; Tengblad, O; Ter-Akopian, G; Terashima, S; Teubig, P; Thies, R; Thoennessen, M; Thomas, T; Thornhill, J; Thungstrom, G; Timar, J; Togano, Y; Tomohiro, U; Tornyi, T; Tostevin, J; Townsley, C; Trautmann, W; Trivedi, T; Typel, S; Uberseder, E; Udias, J; Uesaka, T; Uvarov, L; Vajta, Z; Velho, P; Vikhrov, V; Volknandt, M; Volkov, V; von Neumann-Cosel, P; von Schmid, M; Wagner, A; Wamers, F; Weick, H; Wells, D; Westerberg, L; Wieland, O; Wiescher, M; Wimmer, C; Wimmer, K; Winfield, J S; Winkel, M; Woods, P; Wyss, R; Yakorev, D; Yavor, M; Cardona, J Zamora; Zartova, I; Zerguerras, T; Zgura, I; Zhdanov, A; Zhukov, M; Zieblinski, M; Zilges, A; Zuber, K

2013-01-01

16

Nuclear astrophysics with radioactive ions at FAIR  

E-print Network

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.

R. Reifarth; S. Altstadt; K. Göbel; T. Heftrich; M. Heil; A. Koloczek; C. Langer; R. Plag; M. Pohl; K. Sonnabend; M. Weigand; T. Adachi; F. Aksouh; J. Al-Khalili; M. AlGarawi; S. AlGhamdi; G. Alkhazov; N. Alkhomashi; H. Alvarez-Pol; R. Alvarez-Rodriguez; V. Andreev; B. Andrei; L. Atar; T. Aumann; V. Avdeichikov; C. Bacri; S. Bagchi; C. Barbieri; S. Beceiro; C. Beck; C. Beinrucker; G. Belier; D. Bemmerer; M. Bendel; J. Benlliure; G. Benzoni; R. Berjillos; D. Bertini; C. Bertulani; S. Bishop; N. Blasi; T. Bloch; Y. Blumenfeld; A. Bonaccorso; K. Boretzky; A. Botvina; A. Boudard; P. Boutachkov; I. Boztosun; A. Bracco; S. Brambilla; J. Briz Monago; M. Caamano; C. Caesar; F. Camera; E. Casarejos; W. Catford; J. Cederkall; B. Cederwall; M. Chartier; A. Chatillon; M. Cherciu; L. Chulkov; P. Coleman-Smith; D. Cortina-Gil; F. Crespi; R. Crespo; J. Cresswell; M. Csatlós; F. Déchery; B. Davids; T. Davinson; V. Derya; P. Detistov; P. Diaz Fernandez; D. DiJulio; S. Dmitry; D. Doré; J. Due\\. nas; E. Dupont; P. Egelhof; I. Egorova; Z. Elekes; J. Enders; J. Endres; S. Ershov; O. Ershova; B. Fernandez-Dominguez; A. Fetisov; E. Fiori; A. Fomichev; M. Fonseca; L. Fraile; M. Freer; J. Friese; M. G. Borge; D. Galaviz Redondo; S. Gannon; U. Garg; I. Gasparic; L. Gasques; B. Gastineau; H. Geissel; R. Gernhäuser; T. Ghosh; M. Gilbert; J. Glorius; P. Golubev; A. Gorshkov; A. Gourishetty; L. Grigorenko; J. Gulyas; M. Haiduc; F. Hammache; M. Harakeh; M. Hass; M. Heine; A. Hennig; A. Henriques; R. Herzberg; M. Holl; A. Ignatov; A. Ignatyuk; S. Ilieva; M. Ivanov; N. Iwasa; B. Jakobsson; H. Johansson; B. Jonson; P. Joshi; A. Junghans; B. Jurado; G. Körner; N. Kalantar; R. Kanungo; A. Kelic-Heil; K. Kezzar; E. Khan; A. Khanzadeev; O. Kiselev; M. Kogimtzis; D. Körper; S. Kräckmann; T. Kröll; R. Krücken; A. Krasznahorkay; J. Kratz; D. Kresan; T. Krings; A. Krumbholz; S. Krupko; R. Kulessa; S. Kumar; N. Kurz; E. Kuzmin; M. Labiche; K. Langanke; I. Lazarus; T. Le Bleis; C. Lederer; A. Lemasson; R. Lemmon; V. Liberati; Y. Litvinov; B. Löher; J. Lopez Herraiz; G. Münzenberg; J. Machado; E. Maev; K. Mahata; D. Mancusi; J. Marganiec; M. Martinez Perez; V. Marusov; D. Mengoni; B. Million; V. Morcelle; O. Moreno; A. Movsesyan; E. Nacher; M. Najafi; T. Nakamura; F. Naqvi; E. Nikolski; T. Nilsson; C. Nociforo; P. Nolan; B. Novatsky; G. Nyman; A. Ornelas; R. Palit; S. Pandit; V. Panin; C. Paradela; V. Parkar; S. Paschalis; P. Paw\\lowski; A. Perea; J. Pereira; C. Petrache; M. Petri; S. Pickstone; N. Pietralla; S. Pietri; Y. Pivovarov; P. Potlog; A. Prokofiev; G. Rastrepina; T. Rauscher; G. Ribeiro; M. Ricciardi; A. Richter; C. Rigollet; K. Riisager; A. Rios; C. Ritter; T. Rodríguez Frutos; J. Rodriguez Vignote; M. Röder; C. Romig; D. Rossi; P. Roussel-Chomaz; P. Rout; S. Roy; P. Söderström; M. Saha Sarkar; S. Sakuta; M. Salsac; J. Sampson; J. Sanchez del Rio Saez; J. Sanchez Rosado; S. Sanjari; P. Sarriguren; A. Sauerwein; D. Savran; C. Scheidenberger; H. Scheit; S. Schmidt; C. Schmitt; L. Schnorrenberger; P. Schrock; R. Schwengner; D. Seddon; B. Sherrill; A. Shrivastava; S. Sidorchuk; J. Silva; H. Simon; E. Simpson; P. Singh; D. Slobodan; D. Sohler; M. Spieker; D. Stach; E. Stan; M. Stanoiu; S. Stepantsov; P. Stevenson; F. Strieder; L. Stuhl; T. Suda; K. Sümmerer; B. Streicher; J. Taieb; M. Takechi; I. Tanihata; J. Taylor; O. Tengblad; G. Ter-Akopian; S. Terashima; P. Teubig; R. Thies; M. Thoennessen; T. Thomas; J. Thornhill; G. Thungstrom; J. Timar; Y. Togano; U. Tomohiro; T. Tornyi; J. Tostevin; C. Townsley; W. Trautmann; T. Trivedi; S. Typel; E. Uberseder; J. Udias; T. Uesaka; L. Uvarov; Z. Vajta; P. Velho; V. Vikhrov; M. Volknandt; V. Volkov; P. von Neumann-Cosel; M. von Schmid; A. Wagner; F. Wamers; H. Weick; D. Wells; L. Westerberg; O. Wieland; M. Wiescher; C. Wimmer; K. Wimmer; J. S. Winfield; M. Winkel; P. Woods; R. Wyss; D. Yakorev; M. Yavor; J. Zamora Cardona; I. Zartova; T. Zerguerras; I. Zgura; A. Zhdanov; M. Zhukov; M. Zieblinski; A. Zilges; K. Zuber

2013-10-06

17

Fabrication of radioactive stents by ion implantation  

NASA Astrophysics Data System (ADS)

Worldwide about one million patients require treatment of stenosed coronary arteries annually. Often a tubular stainless steel mesh (stent) is implanted to mechanically support the injured vessel. Restenosis, an abundant complication (20%-30%) can be prevented, if the vessel is treated with ionizing radiation. Stents can deliver radiation if they are made radioactive. The radio isotope 32P is well suited when ion implanted. Radioactive ions sources require high efficiency to keep the radioactive inventory small. Reliability, ease of operation, and maintenance are mandatory. A small emittance is important to minimize losses during mass separation and beam transport. A 2.45 GHz ECR source was developed for the implantation of 32P. The source consists of two coils for the axial and a permanent hexapole for the radial confinement. The microwaves are fed in radially by a loop connected to a silver plated brass tube surrounding the plasma chamber. The plasma chamber is made from Pyrex. Neutron activated phosphorus, containing 30 ppm 32P, is introduced from the rear end on a rod. As support gas D2 is used. By this 32P+ can be separated from (31PD)+. The extraction is done in two steps: 60 kV-30 kV-ground. Mass separation is accomplished by a double focusing 90° magnet (radius 500 mm). During four years of operation about 1000 radioactive stents per year have been provided for animal experiments and clinical trials. Only one maintenance to exchange the extraction system due to degradation of high voltage stability was required so far.

Huttel, Erhard; Kaltenbaek, Johann; Schloesser, Klaus; Schweickert, Hermann

2002-02-01

18

Titanate nanotubes as a promising absorbent for high effective radioactive uranium ions uptake.  

PubMed

In this study, titanate nanotubes with a layered structure were investigated for the uptake of radioactive uranium ions for the first time. The nanotubes have been successfully prepared with a reaction of Ti metal nanopowders and NaOH mixed solution by a novel and effective ultrasonic-assisted hydrothermal method. As the absorbent of radioactive ions, they have the ability to selectively adsorb radioactive U ions from water via ion exchange process and subsequently immobilize these ions in the nanotube sorbents without the need of further treatment after absorption. Sorption induces considerable deformation of the layer structures, resulting in the structures changing from the nanotubes to sheets and having the ability of permanent entrapment of the radioactive cations in these as-grown sheets. Our results have proved that titanate nanotubes can be used as a promising absorbent for the removal of nuclear leaking water at the first time. PMID:22962751

Xu, Mingze; Weil, Guodong; Li, Shuang; Niu, Xiaowei; Chen, Haifeng; Zhang, He; Chubik, M; Gromov, A; Han, Wei

2012-08-01

19

Radioactive Ion Beam Production Capabilities At The Holifield Radioactive Ion Beam Facility  

NASA Astrophysics Data System (ADS)

The Holifield Radioactive Ion Beam Facility (HRIBF) is a national user facility for research with radioactive ion beams (RIBs) that has been in routine operation since 1996. It is located at Oak Ridge National Laboratory (ORNL) and operated by the ORNL Physics Division. The principal mission of the HRIBF is the production of high quality beams of shortlived radioactive isotopes to support research in nuclear structure physics and nuclear astrophysics. HRIBF is currently unique worldwide in its ability to provide neutron-rich fission fragment beams post-accelerated to energies above the Coulomb barrier for nuclear reactions. HRIBF produces RIBs by the isotope separator on-line (ISOL) technique using a particle accelerator system that consists of the Oak Ridge Isochronous Cyclotron (ORIC) driver accelerator, one of the two Injectors for Radioactive Ion Species (IRIS1 or IRIS2) production systems, and the 25-MV tandem electrostatic accelerator that is used for RIB post-acceleration. ORIC provides a light ion beam (proton, deuteron, or alpha) which is directed onto a thick target mounted in a target-ion source (TIS) assembly located on IRIS1 or IRIS2. Radioactive atoms that diffuse from the target material are ionized, accelerated, mass selected, and transported to the tandem accelerator where they are further accelerated to energies suitable for nuclear physics research. RIBs are transported through a beam line system to various experimental end stations including the Recoil Mass Spectrometer (RMS) for nuclear structure research, and the Daresbury Recoil Separator (DRS) for nuclear astrophysics research. HRIBF also includes two off-line ion source test facilities, one low-power on-line ISOL test facility (OLTF), and one high-power on-line ISOL test facility (HPTL). This paper provides an overview and status update of HRIBF, describes the recently completed 4.7M IRIS2 addition and incorporation of laser systems for beam production and purification, and discusses a proposed replacement of the ORIC driver accelerator.

Beene, J. R.; Dowling, D. T.; Gross, C. J.; Juras, R. C.; Liu, Y.; Meigs, M. J.; Mendez, A. J.; Nazarewicz, W.; Sinclair, J. W.; Stracener, D. W.; Tatum, B. A.

2011-06-01

20

Electrolytic Targets for Radioactive Ion Beam Production  

NASA Astrophysics Data System (ADS)

Traditional methods of producing beams of radioactive ions (RIBs) through bombardment of thick targets have employed thermal diffusion to transport radioactive species through the surface of the material. By employing a certain class of materials known as super-ionic conductors as target materials, very fast ionic mobilities can be realized. Since the newly formed RIB species are in an ionic form, electromechanical transport is possible using an applied electric field. Such a technique offers several potential advantages over traditional target systems. First, faster mass transfer of electropositive/negative species through the material could be possible allowing access to shorter-lived RIB species. Second, since highly porous targets geometries would not be required, faster effusive transport to the ion source would be possible along with more efficient heat transfer to cooling media. This report describes the preliminary results of an experiment in which the electrolytic transport of F through ZrO_2/Y_2O3 lattice was investigated and quantified.

Welton, R. F.; Janney, M. A.; Beene, J. R.; Mueller, P. E.; Stracener, D. W.

1999-10-01

21

Evaluation of radioactive scrap metal recycling  

SciTech Connect

This report evaluates the human health risks and environmental and socio-political impacts of options for recycling radioactive scrap metal (RSM) or disposing of and replacing it. Argonne National Laboratory (ANL) is assisting the US Department of Energy (DOE), Office of Environmental Restoration and Waste Management, Oak Ridge Programs Division, in assessing the implications of RSM management alternatives. This study is intended to support the DOE contribution to a study of metal recycling being conducted by the Task Group on Recycling and Reuse of the Organization for Economic Cooperation and Development. The focus is on evaluating the justification for the practice of recycling RSM, and the case of iron and steel scrap is used as an example in assessing the impacts. To conduct the evaluation, a considerable set of data was compiled and developed. Much of this information is included in this document to provide a source book of information.

Nieves, L.A.; Chen, S.Y.; Kohout, E.J.; Nabelssi, B.; Tilbrook, R.W.; Wilson, S.E.

1995-12-01

22

Prototype negative ion sources for radioactive ion beam generation (abstract)  

SciTech Connect

Radioactive ion beams (RIBs) of {sup 17}F and {sup 18}F are of interest for investigation of astrophysical phenomena such as the {open_quotes}hot{close_quotes} CNO cycle and the rp stellar nuclear synthesis processes. In order to generate useful beam intensities of atomic F{sup {minus}}, the species must be efficiently and expediently released from the target material, thermally dissociated from fluoride release products during transport to the ionization chamber of the ion source, and efficiently ionized in the source upon arrival. We have conceived and evaluated two prototype negative ion sources for potential use for RIB generation: a direct extraction source and a kinetic ejection source. Both sources utilize Cs vapor to enhance F{sup {minus}} formation. The mechanical design features, operational parameters, ionization efficiencies for forming atomic F{sup {minus}} and delay times for transport of F and fluoride compounds for the respective sources are presented. The efficiency {eta} for formation and extraction of F{sup {minus}} for the direct extraction negative ion source is found to be {eta}{approximately}1.0{percent}, while the characteristic delay time {tau} for transport of F and fluorides through the source is typically, {eta}{approximately}120 s; the analogous efficiencies and delay times for the kinetic ejection negative ion source are, respectively: {eta}={approximately}3.2{percent} and {tau}={approximately}70 s. {copyright} {ital 1998 American Institute of Physics.}

Alton, G.D. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6368 (United States)] [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6368 (United States); Welton, R.F.; Williams, C. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6368 (United States)] [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6368 (United States); [Oak Ridge Institute of Science and Engineering, Oak Ridge, Tennessee 37831 (United States); Cui, B. [China Institute of Atomic Energy, Beijing (China)] [China Institute of Atomic Energy, Beijing (China); Murray, S.N. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6368 (United States)] [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6368 (United States)

1998-02-01

23

A radioactive ion beam facility using photofission  

NASA Astrophysics Data System (ADS)

Use of a high-power electron linac as the driver accelerator for a Radioactive Ion Beam (RIB) facility is proposed. An electron beam of 30 MeV and 100 kW can produce nearly 5×10 13 fissions/s from an optimized 235U target and about 60% of this from a natural uranium target. An electron beam can be readily transmitted through a thin window at the exit of the accelerator vacuum system and transported a short distance through air to a water-cooled Bremsstrahlung-production target. The Bremsstrahlung radiation can, in turn, be transported through air to the isotope-production target. This separates the accelerator vacuum system, the Bremsstrahlung target and the isotope-production target, reducing remote handling problems. The electron beam can be scanned over a large target area to reduce the power density on both the Bremsstrahlung and isotope-production targets. These features address one of the most pressing technological challenges of a high-power RIB facility, namely the production of high yields of neutron-rich ions with reasonable power density in the target. The cost of an electron linac of the required specifications, including the facility shielding, is significantly less than the cost of any other primary-beam accelerator that could produce a comparable fission yield. A high-power electron linac could also be used with a multifoil helium-jet target. A large number of thin uranium foils could be irradiated with the scanned Bremsstrahlung beam and the fission fragments captured in aerosol-loaded helium and transported to an ion source that is well removed from the intense radiation fields of the primary target. The fission yield would be less than 1% of that available from a thick target, but this approach might be the easiest technical solution to obtain useable yields with manageable radiation-safety problems.

Diamond, William T.

1999-08-01

24

Titanate-based adsorbents for radioactive ions entrapment from water.  

PubMed

This feature article reviews some titanate-based adsorbents for the removal of radioactive wastes (cations and anions) from water. At the beginning, we discuss the development of the conventional ion-exchangeable titanate powders for the entrapment of radioactive cations, such as crystalline silicotitanate (CST), monosodium titanate (MST), peroxotitanate (PT). Then, we specially emphasize the recent progress in the uptake of radioactive ions by one-dimensional (1D) sodium titanate nanofibers and nanotubes, which includes the synthesis and phase transformation of the 1D nanomaterials, adsorption ability (capacity, selectivity, kinetics, etc.) of radioactive cations and anions, and the structural evolution during the adsorption process. PMID:23412572

Yang, Dongjiang; Liu, Hongwei; Zheng, Zhanfeng; Sarina, Sarina; Zhu, Huaiyong

2013-03-21

25

The production of accelerated radioactive ion beams  

SciTech Connect

During the last few years, substantial work has been done and interest developed in the scientific opportunities available with accelerated radioactive ion beams (RIBs) for nuclear physics, astrophysics, and applied research. This interest has led to the construction, development, and proposed development of both first- and second-generation RIB facilities in Asia, North America, and Europe; international conferences on RIBs at Berkeley and Louvain-la-Neuve; and many workshops on specific aspects of RIB production and science. This paper provides a discussion of both the projectile fragmentation, PF, and isotope separator on-line, ISOL, approach to RIB production with particular emphasis on the latter approach, which employs a postaccelerator and is most suitable for nuclear structure physics. The existing, under construction, and proposed facilities worldwide are discussed. The paper draws heavily from the CERN ISOLDE work, the North American IsoSpin Laboratory (ISL) study, and the operating first-generation RIB facility at Louvain-la-Neuve, and the first-generation RIB project currently being constructed at ORNL.

Olsen, D.K.

1993-11-01

26

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

27

Reversible photodeposition and dissolution of metal ions  

DOEpatents

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

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

1994-01-01

28

Extraction simulations and emittance measurements of a Holifield Radioactive Ion Beam Facility electron beam plasma source for radioactive ion beams.  

PubMed

The Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory has a variety of ion sources used to produce radioactive ion beams (RIBs). Of these, the workhorse is an electron beam plasma (EBP) ion source. The recent addition of a second RIB injector, the Injector for Radioactive Ion Species 2 (IRIS2), for the HRIBF tandem accelerator prompted new studies of the optics of the beam extraction from the EBP source. The source was modeled using SIMION V8.0, and results will be presented, including comparison of the emittances as predicted by simulation and as measured at the HRIBF offline ion source test facilities. Also presented will be the impact on phase space shape resulting from extraction optics modifications implemented at IRIS2. PMID:20192452

Mendez, A J; Liu, Y

2010-02-01

29

Extraction simulations and emittance measurements of a Holifield Radioactive Ion Beam Facility electron beam plasma source for radioactive ion beamsa)  

NASA Astrophysics Data System (ADS)

The Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory has a variety of ion sources used to produce radioactive ion beams (RIBs). Of these, the workhorse is an electron beam plasma (EBP) ion source. The recent addition of a second RIB injector, the Injector for Radioactive Ion Species 2 (IRIS2), for the HRIBF tandem accelerator prompted new studies of the optics of the beam extraction from the EBP source. The source was modeled using SIMION V8.0, and results will be presented, including comparison of the emittances as predicted by simulation and as measured at the HRIBF offline ion source test facilities. Also presented will be the impact on phase space shape resulting from extraction optics modifications implemented at IRIS2.

Mendez, A. J.; Liu, Y.

2010-02-01

30

Metallic ions in the equatorial ionosphere  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

31

In-Trap Spectroscopy of Charge-Bred Radioactive Ions  

NASA Astrophysics Data System (ADS)

In this Letter, we introduce the concept of in-trap nuclear decay spectroscopy of highly charged radioactive ions and describe its successful application as a novel spectroscopic tool. This is demonstrated by a measurement of the decay properties of radioactive mass A=124 ions (here, In124 and Cs124) in the electron-beam ion trap of the TITAN facility at TRIUMF. By subjecting the trapped ions to an intense electron beam, the ions are charge bred to high charge states (i.e., equivalent to the removal of N-shell electrons), and an increase of storage times to the level of minutes without significant ion losses is achieved. The present technique opens the venue for precision spectroscopy of low branching ratios and is being developed in the context of measuring electron-capture branching ratios needed for determining the nuclear ground-state properties of the intermediate odd-odd nuclei in double-beta (??) decay.

Lennarz, A.; Grossheim, A.; Leach, K. G.; Alanssari, M.; Brunner, T.; Chaudhuri, A.; Chowdhury, U.; Crespo López-Urrutia, J. R.; Gallant, A. T.; Holl, M.; Kwiatkowski, A. A.; Lassen, J.; Macdonald, T. D.; Schultz, B. E.; Seeraji, S.; Simon, M. C.; Andreoiu, C.; Dilling, J.; Frekers, D.

2014-08-01

32

EBIS charge breeder for radioactive ion beams at ATLAS.  

SciTech Connect

The construction of the Californium Rare Isotope Breeder Upgrade (CARIBU) for the Argonne National Laboratory ATLAS facility is completed and its commissioning is being performed. In its full capacity, the CARIBU facility will use fission fragments from a 1 Curie (Ci) {sup 252}Cf source. The ions will be thermalized and collected into a low-energy ion beam by a helium gas catcher, mass analyzed by an isobar separator, and charge bred to higher charge states for acceleration in ATLAS. To reach energies E/A 10 MeV/u, one should inject ions with charge-to-mass ratio (q/A) {ge} 1/7 into the ATLAS linac. In the first stage, the existing Electron Cyclotron Resonance (ECR) ion source will be used as a charge breeder. The maximum intensity of radioactive ion beams at the output of the gas catcher will not exceed 10{sup 7} ions per second. A charge breeder based on an Electron Beam Ion Source (EBIS) has significant advantages over the ECR option for ion beam intensities up to about 10{sup 9} ions per second, providing 3-4 times higher efficiency and significantly better purity of highly charged radioactive ion beams for further acceleration. The proposed EBIS project for CARIBU will heavily utilize state-of-the-art EBIS technology recently developed at Brookhaven National Laboratory. This will allow us to reduce both the project cost and timescale, simultaneously insuring reliable technical realization of the cutting-edge technology. Several parameters of the CARIBU EBIS charge breeder (EBIS-CB) will be relaxed with respect to the BNL EBIS in favor of higher reliability and lower cost. Technical performance of the CARIBU charge breeder will not suffer from such a relaxation and will provide high efficiency for a whole range of radioactive ion beams. The goal of this paper is to present the initial design of the EBIS charge breeder for radioactive ion beams at ATLAS.

Ostroumov, P.; Kondrashev, S.; Pardo, R.; Savard, G.; Vondrasek, R.; Alessi, J.; Beebe, E.; Pikin, A. (Physics); (BNL)

2010-07-01

33

EBIS charge breeder for radioactive ion beams at ATLAS  

SciTech Connect

The construction of the Californium Rare Isotope Breeder Upgrade (CARIBU) for the Argonne National Laboratory ATLAS facility is completed and its commissioning is being performed. In its full capacity, the CARIBU facility will use fission fragments from a 1 Curie (Ci) {sup 252}Cf source. The ions will be thermalized and collected into a low-energy ion beam by a helium gas catcher, mass analyzed by an isobar separator, and charge bred to higher charge states for acceleration in ATLAS. To reach energies E/A 10 MeV/u, one should inject ions with charge-to-mass ratio (q/A) {ge} 1/7 into the ATLAS linac. In the first stage, the existing Electron Cyclotron Resonance (ECR) ion source will be used as a charge breeder. The maximum intensity of radioactive ion beams at the output of the gas catcher will not exceed 10{sup 7} ions per second. A charge breeder based on an Electron Beam Ion Source (EBIS) has significant advantages over the ECR option for ion beam intensities up to about 10{sup 9} ions per second, providing 3-4 times higher efficiency and significantly better purity of highly charged radioactive ion beams for further acceleration. The proposed EBIS project for CARIBU will heavily utilize state-of-the-art EBIS technology recently developed at Brookhaven National Laboratory. This will allow us to reduce both the project cost and timescale, simultaneously insuring reliable technical realization of the cutting-edge technology. Several parameters of the CARIBU EBIS charge breeder (EBIS-CB) will be relaxed with respect to the BNL EBIS in favor of higher reliability and lower cost. Technical performance of the CARIBU charge breeder will not suffer from such a relaxation and will provide high efficiency for a whole range of radioactive ion beams. The goal of this paper is to present the initial design of the EBIS charge breeder for radioactive ion beams at ATLAS.

Ostroumov, P.; Alessi, J.; Kondrashev, S.; Pardo, R.; Savard, G.; Vondrasek, R.; Beebe, E.; Pikin, A.

2010-07-20

34

EBIS charge breeder for radioactive ion beams at ATLAS  

NASA Astrophysics Data System (ADS)

The construction of the Californium Rare Isotope Breeder Upgrade (CARIBU) for the Argonne National Laboratory ATLAS facility is completed and its commissioning is being performed. In its full capacity, the CARIBU facility will use fission fragments from a 1 Curie (Ci) 252Cf source. The ions will be thermalized and collected into a low-energy ion beam by a helium gas catcher, mass analyzed by an isobar separator, and charge bred to higher charge states for acceleration in ATLAS. To reach energies E/A 10 MeV/u, one should inject ions with charge-to-mass ratio (q/A) >= 1/7 into the ATLAS linac. In the first stage, the existing Electron Cyclotron Resonance (ECR) ion source will be used as a charge breeder. The maximum intensity of radioactive ion beams at the output of the gas catcher will not exceed 107 ions per second. A charge breeder based on an Electron Beam Ion Source (EBIS) has significant advantages over the ECR option for ion beam intensities up to about 109 ions per second, providing 3-4 times higher efficiency and significantly better purity of highly charged radioactive ion beams for further acceleration. The proposed EBIS project for CARIBU will heavily utilize state-of-the-art EBIS technology recently developed at Brookhaven National Laboratory. This will allow us to reduce both the project cost and timescale, simultaneously insuring reliable technical realization of the cutting-edge technology. Several parameters of the CARIBU EBIS charge breeder (EBIS-CB) will be relaxed with respect to the BNL EBIS in favor of higher reliability and lower cost. Technical performance of the CARIBU charge breeder will not suffer from such a relaxation and will provide high efficiency for a whole range of radioactive ion beams. The goal of this paper is to present the initial design of the EBIS charge breeder for radioactive ion beams at ATLAS.

Ostroumov, P.; Kondrashev, S.; Pardo, R.; Savard, G.; Vondrasek, R.; Alessi, J.; Beebe, E.; Pikin, A.

2010-07-01

35

Method for making radioactive metal articles having small dimensions  

DOEpatents

A method for making a radioactive article such as wire, includes the steps of providing a metal article having a first shape, such a cylinder, that is either radioactive itself or can be converted to a second, radioactive isotope by irradiation; melting the metal article one or more times; optionally adding an alloying metal to the molten metal in order to enhance ductility or other properties; placing the metal article having the first shape (e.g., cylindrical) into a cavity in the interior of an extrusion body (e.g., a cylinder having a cylindrical cavity therein); extruding the extrusion body and the article having the first shape located in the cavity therein, resulting in an elongated extrusion body and an article having a second shape; removing the elongated extrusion body, for example by chemical means, leaving the elongated inner article substantially intact; optionally repeating the extrusion procedure one or more times; and then drawing the elongated article to still further elongate it, into wire, foil, or another desired shape. If the starting metal is enriched in a radioactive isotope or a precursor thereof, the end product can provide a more intense radiation source than conventionally manufactured radioactive wire, foil, or the like.

Ohriner, Evan K. (Knoxville, TN)

2000-01-01

36

Charge breeding simulations for radioactive ion beam production  

SciTech Connect

The charge breeding technique is used for radioactive ion beam (RIB) production in order of optimizing the re-acceleration of the radioactive element ions produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1+ to a desired value n+. In order to get high intensity RIB, experiments with charge breeding of very high efficiency could be required. To reach this goal, the charge breeding simulation could help to optimize the high charge state production efficiency by finding more proper parameters for the radioactive 1+ ions. In this paper a device based on an electron beam ion source (EBIS) is considered. In order to study that problem, a code already developed for studying the ion selective containment in an EBIS with RF quadrupoles, BRICTEST, has been modified to simulate the ion charge state breeding rate for different 1+ ion injection conditions. Particularly, the charge breeding simulations for an EBIS with a hollow electron beam have been studied.

Variale, V. [INFN-Bari, Via Orabona, 4, Bari (Italy); Raino, A. C.; Clauser, T. [Physics Department of Bari University and INFN- Bari, Via Orabona, 4, Bari (Italy)

2012-02-15

37

DNA-bound metal ions: recent developments.  

PubMed

The affinity of metal ions for DNA is logical considering that the structure of DNA includes a phosphate backbone with a net-negative charge, a deoxyribose sugar with O atoms, and purine and pyrimidine bases that contain O and N atoms. DNA-metal ion interactions encompass a large area of research that ranges from the most fundamental characterization of DNA-metal ion binding to the role of DNA-bound metal ions in disease and human health. Alternative DNA base pairing mediated by metal binding is also being investigated and manipulated for applications in logic gates, molecular machines, and nanotechnology. This review highlights recent work aimed at understanding interactions of redox-active metal ions with DNA that provides a better understanding of the mechanisms by which various types of oxidative DNA damage (strand breakage and base modifications) occur. Antioxidants that mitigate oxidative DNA damage by coordinating metal ions that produce reactive oxygen species are addressed, as well as recent work on the effect of DNA-metal ion interactions and the efficacy of quinolone-based antibacterial drugs. Recent advances in metal-mediated base pairing that triggers conformational changes in DNA structure for use as selective metal ion sensors and novel nanotechnology applications are also included. PMID:25367620

Morris, Daniel L

2014-10-01

38

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

39

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

PubMed Central

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 monovalent cations prevent nonspecific association of divalent ions with nucleic acids provides a novel and powerful means to examine site-specific metal ion binding isolated from complicating effects of the ion atmosphere. Using these high monovalent cation solution conditions we have monitored the affinity of a series of divalent metal ions for two site-specific metal ion binding sites in the P4-P6 domain of the Tetrahymena group I intron ribozyme. The metal ion core of this highly structured RNA binds two divalent metal ions under these conditions. Despite multiple metal ion–RNA interactions observed in the X-ray crystallographic structure of P4-P6 RNA at the metal ion binding sites, these sites exhibit low specificity among Mn2+, Mg2+, Ca2+, Ni2+, and Zn2+. Nevertheless, the largest divalent metal ions tested, Sr2+ and Ba2+, were excluded from binding, exhibiting affinities at least two orders of magnitude weaker than observed for the other metal ions. Thus, a picture emerges of two metal ion binding sites, each with a high tolerance for metal ions with different properties but also with limits to accommodation. These limits presumably arise from steric or electrostatic features of the metal ion binding sites. PMID:17616553

Travers, Kevin J.; Boyd, Nathan; Herschlag, Daniel

2007-01-01

40

Scrap metal management issues associated with naturally occurring radioactive material  

SciTech Connect

Certain industrial processes sometimes generate waste by-products that contain naturally occurring radioactive material (NORM) at elevated concentrations. Some industries, including the water treatment, geothermal energy, and petroleum industries, generate scrap metal that may be contaminated with NORM wastes. Of these three industries, the petroleum industry probably generates the largest quantity of NORM-contaminated equipment, conservatively estimated at 170,000 tons per year. Equipment may become contaminated when NORM-containing scale or sludge accumulates inside water-handling equipment. The primary radionuclides of concern in these NORM wastes are radium-226 and radium-228. NORM-contaminated equipment generated by the petroleum industry currently is managed several ways. Some equipment is routinely decontaminated for reuse; other equipment becomes scrap metal and may be disposed of by burial at a licensed landfill, encapsulation inside the wellbore of an abandoned well, or shipment overseas for smelting. In view of the increased regulatory activities addressing NORM, the economic burden of managing NORM-contaminated wastes, including radioactive scrap metal, is likely to continue to grow. Efforts to develop a cost-effective strategy for managing radioactive scrap metal should focus on identifying the least expensive disposition options that provide adequate protection of human health and the environment. Specifically, efforts should focus on better characterizing the quantity of radioactive scrap available for recycle or reuse, the radioactivity concentration levels, and the potential risks associated with different disposal options.

Smith, K.P.; Blunt, D.L.

1995-08-01

41

Nuclear astrophysics at the Holifield Radioactive Ion Beam Facility  

NASA Astrophysics Data System (ADS)

Reactions involving radioactive nuclei play an important role in explosive stellar events such as novae, supernovae, and X-ray bursts. The development of accelerated, proton-rich radioactive ion beams provides a tool for directly studying many of the reactions that fuel explosive hydrogen burning. The experimental nuclear astrophysics program at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory is centered on absolute cross section measurements of these reactions with radioactive ion beams. Beams of F-17 and F-18, important nuclei in the hot-CNO cycle, are currently under development at HRIBF. Progress in the production of intense radioactive fluorine beams is reported. The Daresbury Recoil Separator (DRS) has been installed at HRIBF as the primary experimental station for nuclear astrophysics experiments. The DRS will be used to measure reactions in inverse kinematics with the techniques of direct recoil detection, delayed-activity recoil detection, and recoil-gamma coincidence measurements. The first astrophysics experiments to be performed at HRIBF, mA the application of the recoil separator in these measurements, are discussed.

Blackmon, Jeff C.

1996-01-01

42

ISOLATION OF RADIOACTIVE METALS FROM LIQUID WASTES  

EPA Science Inventory

Metals are present in many waste streams, and pose challenges with regard to their disposal. Release of metals into the environment presents both human health and ecological concerns. As a result, efforts are directed at reducing their toxicity, bioavailability, and environment...

43

Fusion Induced by Radioactive Ion Beams  

E-print Network

The use of radioactive beams opens a new frontier for fusion studies. The coupling to the continuum can be explored with very loosely bound nuclei. Experiments were performed with beams of nuclei at or near the proton and neutron drip-lines to measure fusion and associated reactions in the vicinity of the Coulomb barrier. In addition, the fusion yield is predicted to be enhanced in reactions involving very neutron-rich unstable nuclei. Experimental measurements were carried out to investigate if it is feasible to use such beams to produce new heavy elements. The current status of these experimental activities is given in this review.

J. F. Liang; C. Signorini

2005-04-26

44

Spin Observables in Reactions with Radioactive Ion Beams  

SciTech Connect

Polarization observables in nuclear reactions with exotic nuclei will provide important information concerning structural properties of nuclei and reaction mechanisms. We are currently engaged in exploring the use of polarization observables with radioactive ion beams and in the development of a polarized cryogenic target.

Galindo-Uribarri, Alfredo {nmn} [ORNL; Urrego Blanco, Juan Pablo [ORNL

2007-01-01

45

Cooling of radioactive ions with the Penning trap REXTRAP  

NASA Astrophysics Data System (ADS)

Cooling of radioactive ion beams in a Penning trap is an essential component of the post-accelerator REX-ISOLDE at CERN. Prior to their charge-breeding and acceleration, ions from the on-line mass separator ISOLDE are accumulated, cooled and bunched with REXTRAP. This beam preparation provides short ion pulses with low emittance, key ingredient for a high efficiency of REX-ISOLDE. Two different cooling techniques have been investigated with REXTRAP. Both rely on the use of a buffer gas as the coolant but differ in the way the transversal compression of the stored ion cloud is achieved. Sideband cooling with a light buffer gas as coolant is the standard technique used at REXTRAP so far. With this technique an efficiency of about 45% for the injection, cooling, and extraction process has been obtained for stable and radioactive ions. For about 105 simultaneously stored ions the resulting emittance of the extracted ion pulses is about 10? mm mrad at 30 keV beam energy. For much larger numbers of ions shifts of the resonance frequency of the sideband excitation are observed together with an emittance growth. As an alternative to sideband cooling a "rotating wall" technique was tested. First results with rotating dipole as well as quadrupole fields are presented.

Ames, F.; Bollen, G.; Delahaye, P.; Forstner, O.; Huber, G.; Kester, O.; Reisinger, K.; Schmidt, P.

2005-02-01

46

COMPUTATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS  

EPA Science Inventory

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

47

Ion sources for initial use at the Holifield Radioactive Ion Beam Facility  

SciTech Connect

The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the HRIBF because of its low emittance, relatively high ionization efficiencies and species versatility, and because it has been engineered for remote installation, removal and servicing as required for safe handling in a high-radiation-level ISOL facility. Prototype plasma-sputter negative ion sources and negative surface-ionization sources are also under design consideration for generating negative radioactive ion beams from high-electron-affinity elements. The design features of these sources and expected efficiencies and beam qualities (emittances) will be described in this report.

Alton, G.D. [Oak Ridge National Lab., TN (United States)

1994-05-01

48

Ion sources for initial use at the Holifield Radioactive Ion Beam Facility  

SciTech Connect

The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the HRIBF because of its low emittance, relatively high ionization efficiencies and species versatility, and because it has been engineered for remote installation, removal and servicing as required for safe handling in a high-radiation-level ISOL facility. Prototype plasma-sputter negative ion sources and negative surface-ionization sources are also under design consideration for generating negative radioactive ion beams from high-electron-affinity elements. The design features of these sources and expected efficiencies and beam qualities (emittances) will be described in this report.

Alton, G.D.

1993-12-31

49

Expansion of the radioactive ion beam program at Argonne  

NASA Astrophysics Data System (ADS)

The Argonne Tandem Linear Accelerator System (ATLAS) at Argonne National Laboratory (ANL) provides a wide range of stable ion beams and radioactive beams which have contributed to our understanding of nuclear structure and reactions. Until now, most radioactive ion beams at ATLAS were produced in flight using light-ion reactions such as (p, n), (d, n), (d, p), (d,3He), and (3He,n). Within the next few months, the radioactive ion beam program at ATLAS will acquire much extended, new capabilities with the commissioning of a new facility: the CAlifornium Rare Isotope Breeder Upgrade (CARIBU). CARIBU will supply ion beams of 252Cf fission fragments, which are thermalized in a gas catcher. The singly- and doubly-charged ions extracted from the gas catcher will be mass-separated and either delivered to a low-energy experimental area, or charge bred with a modified ECR source and subsequently reaccelerated by the ATLAS facility. Properties of hundreds of these neutron-rich nuclides will be investigated using ion traps, decay stations, the newly commissioned HELical Orbit Spectrometer (HELIOS), and other available experimental equipment such as Gammasphere and the FMA. HELIOS was constructed to take advantage of rare ion beams, such as those provided by CARIBU, through light-ion transfer reactions in inverse kinematics, and represents a new approach to the study of direct reactions in inverse kinematics which avoids kinematic broadening. Experiments are currently being conducted with HELIOS, and first results with the d(28Si,p) and d(12B,p) reactions have shown excellent energy resolution.

Clark, J. A.

2011-01-01

50

Pseudo ribbon metal ion beam source  

SciTech Connect

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

Stepanov, Igor B., E-mail: stepanovib@tpu.ru; Ryabchikov, Alexander I.; Sivin, Denis O.; Verigin, Dan A. [Tomsk Polytechnic University, 30 Lenina Avenue, Tomsk 634050 (Russian Federation)] [Tomsk Polytechnic University, 30 Lenina Avenue, Tomsk 634050 (Russian Federation)

2014-02-15

51

Pseudo ribbon metal ion beam source.  

PubMed

The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface. PMID:24593634

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

2014-02-01

52

Pseudo ribbon metal ion beam source  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

53

Radioactively Contaminated Scrap Metal An International Approach to Monitoring, Interception & Managing  

E-print Network

Radioactively Contaminated Scrap Metal An International Approach to Monitoring, Interception of uncontrolled radioactive source incidents. Aside from radiation exposure to workers and the public, this unwanted radioactive scrap material causes environmental and facility contamination with cleanup costs

54

Heavy metal ions removal by chelating resin  

Microsoft Academic Search

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

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

2005-01-01

55

DIAGNOSTIC SYSTEM DEDICATED TO THE RADIOACTIVE ION BEAMS AT THE SPIRAL FACILITY  

E-print Network

DIAGNOSTIC SYSTEM DEDICATED TO THE RADIOACTIVE ION BEAMS AT THE SPIRAL FACILITY B. LAUNE, M. MALARD beam lines with the radioactive ion beams, dedicated diagnostic sytems have been built. This equipment Introduction The SPIRAL Radioactive Ion Beam (R.lB.) Facility has already been described elsewhere [1J

Boyer, Edmond

56

The Use of Induction Melting for the Treatment of Metal Radioactive Waste - 13088  

SciTech Connect

The aim of the work is to assess the efficacy of induction melting metal for recycling radioactive waste in order to reduce the volume of solid radioactive waste to be disposed of, and utilization of the metal. (authors)

Zherebtsov, Alexander; Pastushkov, Vladimir; Poluektov, Pavel; Smelova, Tatiana; Shadrin, Andrey [JSC 'VNIINM', Rogova st., 5, 123098, Moscow (Russian Federation)] [JSC 'VNIINM', Rogova st., 5, 123098, Moscow (Russian Federation)

2013-07-01

57

Selection and design of ion sources for use at the Holifield Radioactive Ion Beam Facility  

SciTech Connect

The Holifield Radioactive Ion beam Facility now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility. The choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. Although direct-extraction negative ion sources are clearly desirable, the ion formation efficiencies are often too low for practical consideration; for this situation, positive ion sources, in combination with charge exchange, are the logical choice. The high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the facility because of its low emittance, relatively high ionization efficiencies and species versatility, and because it has been engineered for remote installation, removal and servicing as required for safe handling in a high-radiation-level ISOL facility. The source will be primarily used to generate ion beams from elements with intermediate to low electron affinities. Prototype plasma-sputter negative ion sources and negative surface-ionization sources are under design consideration for generating radioactive ion beams from high-electron-affinity elements. The design features of these sources and expected efficiencies and beam qualities (emittances) will be described in this report.

Alton, G.D.; Haynes, D.L.; Mills, G.D.; Olsen, D.K.

1993-12-31

58

Sorption of metal ions on alumina  

SciTech Connect

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

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

1997-10-01

59

Charge breeding of radioactive ions with EBIS and EBIT  

E-print Network

A charge state breeder, which transforms externally injected singly charged ions to a higher charge state q+, is an important tool which has applications within atomic, nuclear and even particle physics. The charge breeding concept of radioactive ions has already been demonstrated at REX-ISOLDE/CERN with the use of an Electron beam Ion Source (EBIS) and at several facilities employing Electron Resonance Cyclotron Ion Sources (ECRIS). As will be demonstrated in this paper, EBIS and Electron Beam Ion Traps (EBIT), are well suited for the task as they are capable of delivering clean, highly charged beams within a short transformation time. The increasing demand for highly charged ions of all kind of elements and isotopes, stable and radioactive, to be used for low-energy experiments such as TITAN at TRIUMF and MATS at FAIR, but also for post-acceleration to higher energies, is now pushing the development of the breeders. The next challenge will be to satisfy the needs, for example space-charge capacity, of the s...

Wenander, Fredrik

2010-01-01

60

Transport of radioactive ions in soil by electrokinetics  

SciTech Connect

An electrokinetic approach is being evaluated for in situ soil remediation at the Hanford Site in Richland, Washington. This approach uses an applied electric field to induce transport of both radioactive and hazardous waste ions in soil. The work discussed in this paper involves the development of a new method to monitor the movement of the radioactive ions within the soil during the electrokinetic process. A closed cell and a gamma counter were used to provide iii situ measurements of {sup 137}Cs and {sup 60}Co movement in Hanford soil. Preliminary results show that for an applied potential of 200 V over approximately 200 hr, {sup 137}Cs and {sup 60}60 were transported a distance of 4 to 5 in. The monitoring technique demonstrated the feasibility of using electrokinetics for soil separation applications.

Buehler, M.F.; Surma, J.E.; Virden, J.W.

1994-10-01

61

An ion source module for the Beijing Radioactive Ion-beam Facility  

SciTech Connect

An ion source module is developed for Beijing Radioactive Ion-beam Facility. The ion source module is designed to meet the requirements of remote handling. The connection and disconnection of the electricity, cooling and vacuum between the module and peripheral units can be executed without on-site manual work. The primary test of the target ion source has been carried out and a Li{sup +} beam has been extracted. Details of the ion source module and its primary test results are described.

Cui, B., E-mail: cui@ciae.ac.cn; Huang, Q.; Tang, B.; Ma, R.; Chen, L.; Ma, Y. [China Institute of Atomic Energy, Beijing (China)] [China Institute of Atomic Energy, Beijing (China)

2014-02-15

62

The SPES radioactive ion beam project of INFN  

NASA Astrophysics Data System (ADS)

The SPES Radioactive Ion Beam facility at INFN-LNL is presently in the construction phase. The facility is based on the Isol (Isotope separation on-line) method with an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.20.5 mA. Neutron-rich radioactive ions are produced by proton induced Uranium fission at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting Linac at energies of 10A MeV for masses in the region A = 130 amu. The expected secondary beam rates are of the order of 107 - 109 pps. Aim of the SPES project is to provide a facility for high intensity radioactive ion beams for nuclear physics research as well as to develop an interdisciplinary research center based on the cyclotron proton beam.

de Angelis, Giacomo; Spes Collaboration; Prete, G.; Andrighetto, A.; Manzolaro, M.; Corradetti, S.; Scarpa, D.; Rossignoli, M.; Monetti, A.; Lollo, M.; Calderolla, M.; Vasquez, J.; Zafiropoulos, D.; Sarchiapone, L.; Benini, D.; Favaron, P.; Rigato, M.; Pegoraro, R.; Maniero, D.; Calabretta, L.; Comunian, M.; Maggiore, M.; Lombardi, A.; Piazza, L.; Porcellato, A. M.; Roncolato, C.; Bisoffi, G.; Pisent, A.; Galatà, A.; Giacchini, M.; Bassato, G.; Canella, S.; Gramegna, F.; Valiente, J.; Bermudez, J.; Mastinu, P. F.; Esposito, J.; Wyss, J.; Russo, A.; Zanella, S.

2014-07-01

63

The SPES Radioactive-Ion Beam Facility of INFN  

NASA Astrophysics Data System (ADS)

A new radioactive-ion beam (RIB) facility (SPES) is presently under construction at the Legnaro National Laboratories of INFN. The SPES facility is based on the ISOL method using a UCx direct target able to sustain a power of 10 kW. The primary proton beam will be provided by a high-current cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.2-0.5 mA. Neutron-rich radioactive ions will be produced by proton-induced fission on a uranium target at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes will be re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV for masses in the region A=130 amu. The expected secondary beam rates are of the order of 107-109 pps. The aim of the SPES facility is to deliver high-intensity radioactive-ion beams of neutron-rich nuclei for nuclear physics research, as well as to be an interdisciplinary research center for radioisotope production for medicine and for neutron beams.

de Angelis, G.; Prete, G.; Andrighetto, A.; Manzolaro, M.; Corradetti, S.; Scarpa, D.; Rossignoli, M.; Monetti, A.; Lollo, M.; Calderolla, M.; Vasquez, J.; Zafiropoulos, D.; Sarchiapone, L.; Benini, D.; Favaron, P.; Rigato, M.; Pegoraro, R.; Maniero, D.; Comunian, M.; Maggiore, M.; Lombardi, A.; Piazza, L.; Porcellato, A. M.; Roncolato, C.; Bisoffi, G.; Pisent, A.; Galatà, A.; Giacchini, M.; Bassato, G.; Canella, S.; Gramegna, F.; Valiente, J.; Bermudez, J.; Mastinu, P. F.; Esposito, J.; Wyss, J.; Russo, A.; Zanella, S.; Calabretta, L.

2015-11-01

64

Site of transition metal ions in ion-exchanged metal-doped glasses  

Microsoft Academic Search

Metal-for-alkali ion-exchange is largely used to dope surface layer of glass with metal ions so inducing a modification of the optical properties of the doped layer, useful to fabricate low-loss optical waveguides. X-ray absorption spectroscopy is a particularly important technique used to investigate the site of the metal ions introduced into the matrix, in specific cases also singling out the

C. Maurizio; F. D’Acapito; C. Sada; E. Cattaruzza; F. Gonella; G. Battaglin

2008-01-01

65

ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS  

EPA Science Inventory

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

66

BEARS: A radioactive ion beam initiative at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Advanced Electron Cyclotron Resonance ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p, n) and (p, {alpha}) reactions on low-Z targets. Tests at the 88'' Cyclotron lead to projections of initial {sup 11}C beams of 2x10{sup 8} ions/sec {sup 14}O beams of 1x10{sup 6} ions/sec. Construction of BEARS is expected to be completed in the spring of 1999.

Powell, J.; Guo, F. Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C. M.; McMahan, P.; Moltz, D. M.; Norman, E. B.; O'Neil, J. P.; Rowe, M. W.; VanBrocklin, H. F.; Wutte, D.; Xie, Z. Q.; Xu, X. J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Haustein, P. E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1999-06-10

67

BEARS: A radioactive ion beam initiative at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88{sup {double_prime}} Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88{sup {double_prime}} Cyclotron{close_quote}s Advanced Electron Cyclotron Resonance ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p, n) and (p, {alpha}) reactions on low-Z targets. Tests at the 88{sup {double_prime}} Cyclotron lead to projections of initial {sup 11}C beams of 2{times}10{sup 8}&hthinsp;ions/sec {sup 14}O beams of 1{times}10{sup 6}&hthinsp;ions/sec. Construction of BEARS is expected to be completed in the spring of 1999. {copyright} {ital 1999 American Institute of Physics.}

Powell, J.; Guo, F.Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.M.; McMahan, P.; Moltz, D.M.; Norman, E.B.; O`Neil, J.P.; Rowe, M.W.; VanBrocklin, H.F.; Wutte, D.; Xie, Z.Q.; Xu, X.J.; Cerny, J. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] Haustein, P.E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1999-06-01

68

Detection of Heavy Metal Ions Based on Quantum Point Contacts  

E-print Network

Detection of Heavy Metal Ions Based on Quantum Point Contacts Vasanth Rajagopalan, Salah Boussaad. The ability to detect trace amounts of metal ions is important because of the toxicity of heavy metal ions on many living organisms and the consequence of heavy metal ions not being biodegradable. To date, heavy

Zhang, Yanchao

69

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

70

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

E-print Network

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

Das, Rhiju

71

Release of Radioactive Scrap Metal/Scrap Metal (RSM/SM) at Nevada Test Site (NTS)  

SciTech Connect

Reynolds Electrical and Engineering Company, Inc. (REECo) is the prime contractor to the US Department of Energy (DOE) in providing service and support for NTS operations. Mercury Base Camp is the main control point for the many forward areas at NTS, which covers 1,350 square miles. The forward areas are where above-ground and underground nuclear tests have been performed over the last 41 years. No metal (or other material) is returned to Mercury without first being tested for radioactivity. No radioactive metals are allowed to reenter Mercury from the forward areas, other than testing equipment. RAMATROL is the monitor check point. They check material in various ways, including swipe tests, and have a large assortment of equipment for testing. Scrap metal is also checked to address Resource Conservation and Recovery Act concerns. After addressing these issues, the scrap metals are categorized. Federal Property Management Regulations (FPMR) are followed by REECo. The nonradioactive scrap material is sold through the GSA on a scheduled basis. Radioactive scrap metal are presently held in forward areas where they were used. REECo has gained approval of their Nevada Test Site Defense Waste Acceptance Criteria, Certification, and Transfer Requirements, NVO-325 application, which will allow disposal on site, when RSM is declared a waste. The guideline that REECo uses for release limits is DOE Order 5480.11, Radiation Protection for Occupational Works, Attachment 2, Surface Radioactivity Guides, of this order, give release limits for radioactive materials. However, the removal of radioactive materials from NTS require approval by DOE Nevada Operations Office (DOE/NV) on a case-by-case basis. Requirements to consider before removal are found in DOE Order 5820.2A, Radioactive Waste Management.

Not Available

1993-07-01

72

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

E-print Network

Study of a liquid metal ion source for external ion injection into electron-beam ion source A York 11973 Presented on 13 September 2005; published online 22 March 2006 A liquid metal ion source LMIS has several attractive features as an external injector of primary ions mostly metallic ions

73

Direct conversion of radioactive and chemical waste containing metals, ceramics, amorphous solids, and organics to glass  

SciTech Connect

The Glass Material Oxidation and Dissolution System (CMODS) is a new process for direct conversion of radioactive, mixed, and chemical wastes to glass. The wastes can be in the chemical forms of metals, ceramics, amorphous solids, and organics. GMODS destroys organics and it incorporates heavy metals and radionuclides into a glass. Processable wastes may include miscellaneous spent fuels (SF), SF hulls and hardware, plutonium wastes in different forms, high-efficiency particulate air (HEPA) filters, ion-exchange resins, failed equipment, and laboratory wastes. Thermodynamic calculations indicate theoretical feasibility. Small-scale laboratory experiments (< 100 g per test) have demonstrated chemical laboratory feasibility for several metals. Additional work is needed to demonstrate engineering feasibility.

Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

1994-05-02

74

Correlation of metal ion toxicities to mice.  

PubMed

Recently reported correlations of acute ip LD50 metal ion toxicities to mice by Turner et al. (1983), have been re-investigated using the ion-specific parameters reported by Kaiser (1980) for sublethal metal ion toxicities to Daphnia magna. For the 15 ions with partially or completely filled d-shells, Rh(III), Fe(III), Cr(III), Mn(II), Co(II), Pd(II), Ni(II), Au(III), Zn(II), Pt(II), Ag(I), Cu(II), In(III), Hg(II), and Cd(II), a correlation coefficient of r2 = 0.76 is found. This is a significant improvement over the value of r2 = 0.36 observed for the 14 divalent metal ions by Turner et al. with the softness parameter sigma as the independent variable. This re-investigation proves the applicability of the ionization potential and redox potential derived parameters for the quantitative correlation of metal ion toxicities to both aquatic and terrestrial biota. PMID:4081779

Kaiser, K L

1985-11-01

75

Radioactive Ion Beams with the HHIRF (Holifield Heavy Ion Research Facility) accelerators  

Microsoft Academic Search

Our present understanding of nuclear structure is almost completely based on facts obtained for nuclei that can be produced with stable projectiles and targets which have equilibrated for a significant fraction of the lifetime of the universe. The use of Radioactive Ion Beams (RIB) could overcome this limitation and provide unique opportunities for the study of nuclear structure with nuclei

M. J. Meigs; G. D. Alton; C. Baktash; D. T. Dowling; J. D. Garrett; D. L. Haynes; C. M. Jones; R. C. Juras; I. Y. Lee; G. D. Mills; S. W. Mosko; D. K. Olsen; B. A. Tatum; K. S. Toth; H. K. Carter

1990-01-01

76

Fluorescent ion indicators for detecting heavy metals  

NASA Astrophysics Data System (ADS)

A series of fluorescent ion indicators were tested for their spectral response to submicromolar levels of 13 divalent and trivalent metal ions in aqueous solution. Upon binding their target ions, these fluorescent compounds exhibit changes in fluorescence emission intensity that are easily detectable, making them useful for direct the detection of soluble heavy metal ions including Hg2+, Cu2+, Ni2+ and Cd2+. The fluorescence response of these indicators to ion binding results from photoinduced electron transfer effects, fluorophore/quencher interactions, fluorescence quenching by heavy metal ions or a combination of these processes. The majority of the indicators we tested bind their target ions reversibly with dissociation constants (Kd) near 1 (mu) M (approximately 1 ppm) and detection limits near 100 nM (approximately 100 ppb) at pH 7. However, several indicators exhibit very high affinity for their target ion; for example, Magnesium GreenTM binds Zn2+ with a Kd near 20 nM. All the indicators synthesized and tested are based on water-soluble fluorophores that have high fluorescence quantum yields (from 0.3 to 0.7) and can be excited with an Ar laser, fluorometer or hand- held UV lamp. Furthermore, the excitation and emission spectra of these indicators are insensitive to pH changes over the range of 5 to 10, as well as to high concentrations of K+, Na+, Ca2+ and Mg2+. These properties make the indicators useful for the direct measurement of metal ions in solutions, such as biological fluids, sea water and waste streams, that contain high concentrations of salts.

Kuhn, Michael A.; Hoyland, Brian; Carter, Scott; Zhang, Cailan; Haugland, Richard P.

1995-05-01

77

Ion exchangers in radioactive waste management: natural Iranian zeolites.  

PubMed

Five samples of natural zeolites from different parts of Iran were chosen for this study. In order to characterize and determine their structures, X-ray diffraction and infrared spectrometry were carried out for each sample. The selective absorption properties of each zeolite were found by calculating the distribution coefficient (K(d)) of various simulated wastes which were prepared by spiking the radionuclides with (131)I, (99)Mo, (153)Sm, (140)La and (147)Nd. All the zeolite samples used in this study had extremely high absorption value towards (140)La; clinoptolite from Mianeh and analsite from Ghalehkhargoshi showed good absorption for (147)Nd; clinoptolite from Semnan and clinoptolite from Firozkoh showed high absorption for (153)Sm; mesolite from Arababad Tabas showed good absorption for (99)Mo; and finally mesolite from Arababad Tabas, clinoptolite from Semnan and clinoptolite from Firozkoh could be used to selectively absorb (131)I from the stimulated waste which was prepared. The natural zeolites chosen for these studies show a similar pattern to those synthetic ion exchangers in the literature and in some cases an extremely high selectivity towards certain radioactive elements. Hence the binary separation of radioactive elements could easily be carried out. Furthermore, these zeolites, which are naturally occurring ion exchangers, are viable economically and extremely useful alternatives in this industry. PMID:16099667

Nilchi, A; Maalek, B; Khanchi, A; Ghanadi Maragheh, M; Bagheri, A; Savoji, K

2006-01-01

78

Low energy nuclear reactions with RIBRAS, Radioactive Ion Beam in Brasil, system  

Microsoft Academic Search

RIBRAS, Radioactive Ion beam in Brasil, is a system based on superconducting solenoids which can produce low energy RNB (Radioactive Nuclear Beams) at the University of São Paulo, Brazil. Secondary radioactive beams of light particles such as 6He, 7Be and 8Li have been produced and low energy elastic scattering and transfer reaction experiments have been performed. The recent scientific program

V. Guimarães; A. Lépine-Szily; R. Lichtenthäler; P. N. de Faria; A. Barioni; K. C. C. Pires; V. Morcelle; D. R. Mendes; J. C. Zamora; M. C. Morais; R. P. Condori; E. A. Benjamim; D. S. Monteiro; E. Crema; A. M. Moro; J. Lubian

2011-01-01

79

Metal ions and human sperm mannose receptors.  

PubMed

Zinc and lead concentrations were measured in seminal plasma from fertile donors, infertile men with varicocoele and men undergoing work-ups for in vitro fertilization. Ejaculated spermatozoa from these subjects were incubated in vitro with various metal ions and/or dibromoethane and dibromochloropropane. Mannose receptor expression was correlated with metal and toxicant levels. Sperm distributions of potassium channels were compared with lead ions and calcium channels with zinc ions. Mannose receptor expression by capacitated spermatozoa increased linearly with seminal plasma zinc levels, and correlated inversely with lead levels. Cobalt had no effect on mannose receptor expression, but nickel had a concentration-dependent biphasic effect. Mannose receptor expression was not affected by dibromoethane and dibromochloropropane if the cholesterol content of the sperm membrane was high, but mannose receptor expression was decreased in low cholesterol spermatozoa by exposures below estimated permissive exposure limits. Potassium channels and lead ions co-localized over the entire head of human spermatozoa, while both calcium channels and zinc ions were confined to the equatorial segment of the head. Mannose receptor expression on the external surface of the human sperm plasma membrane is a biomarker for the effects of transition and heavy metals and organic toxicants on sperm fertility potential. PMID:11021525

Benoff, S; Cooper, G W; Centola, G M; Jacob, A; Hershlag, A; Hurley, I R

2000-09-01

80

Material Removes Heavy Metal Ions From Water  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

81

Radioactive Ions Production Ring for Beta-Beams  

E-print Network

Within the FP7 EUROnu program, Work Package 4 addresses the issues of production and acceleration of 8Li and 8B isotopes through the Beta-Beam complex, for the production of electron-neutrino. One of the major critical issues is the production of a high enougth ion ßux, to fulÞll the requirements for physics. In alternative to the direct ISOL production method, a new ap- proach is proposed in [1]. The idea is to use a compact ring for Litium ions at 25 MeV and an internal He or D target, in which the radioactive-isotopes production takes place. The beam is expected to survive for several thousands of turns, therefore cooling in 6D is required and, according this scheme, the ionization cooling provided by the target itself and a suitable RF system would be sufÞcient. We present some preliminary work on the Production ring lat- tice design and cooling issues, for the 7Li ions, and propose plans for future studies, within the EUROnu program.

Benedetto, E; Wehner, J

2010-01-01

82

Polymer nanocomposites based on transition metal ion modified organoclays  

E-print Network

Polymer nanocomposites based on transition metal ion modified organoclays Pranav Nawani a , Priya: Transition metal ion; Organoclay; Nanocomposite 1. Introduction Thermoplastic nanocomposites with improved; accepted 4 December 2006 Available online 3 January 2007 Abstract A unique class of nanocomposites

Frenkel, Anatoly

83

Benchmark study of induced radioactivity with heavy ions on copper and stainless steel targets  

Microsoft Academic Search

The activation of structures and surroundings of new high intensity heavy ion accelerators like the Facility for Antiproton and Ion Research (FAIR) is an important issue. Monte Carlo codes such as FLUKA allow to predict the production of individual radioactive isotopes and the induced radioactivity which causes the main contribution to the radiation exposure of personnel. The aim of this

E. Kozlova; I. Strasik; A. Fertman; E. Mustafin; T. Radon; R. Hinca; M. Pavlovic; G. Fehrenbacher; H. Geissel; A. Golubev; H. Iwase; D. Schardt

84

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. PMID:22736759

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

2012-01-01

85

Low-energy radioactive ion beam production of 22Mg  

NASA Astrophysics Data System (ADS)

The 22Mg nucleus plays an important role in nuclear astrophysics, specially in the 22Mg(?,p)25Al and proton capture 22Mg(p,?)23Al reactions. It is believed that 22Mg is a waiting point in the ?p-process of nucleosynthesis in novae. We proposed a direct measurement of the 22Mg+? resonance reaction in inverse kinematics using a radioactive ion (RI) beam. A 22Mg beam of 3.73 MeV/u was produced at CRIB (Center for Nuclear Study (CNS) low-energy RI Beam) facility of the University of Tokyo located at RIKEN (Japan) in 2011. In this paper we present the results about the production of the 22Mg beam used for the direct measurement of the scattering reaction 22Mg(?,?)22Mg, and the stellar reaction 22Mg(?,p)25Al in the energy region concerning an astrophysical temperature of T9=1-3 GK.

Duy, N. N.; Kubono, S.; Yamaguchi, H.; Kahl, D.; Wakabayashi, Y.; Teranishi, T.; Iwasa, N.; Kwon, Y. K.; Khiem, L. H.; Kim, Y. H.; Song, J. S.; Hu, J.; Ayyad, Y.

2013-09-01

86

Intravascular brachytherapy with radioactive stents produced by ion implantation  

NASA Astrophysics Data System (ADS)

About 1 million patients are treated for stenosis of coronary arteries by percutaneous balloon angioplasty annually worldwide. In many cases a so called stent is inserted into the vessel to keep it mechanically open. Restenosis is observed in about 20-30% of these cases, which can be treated by irradiating the stented vessel segment. In our approach, we utilized the stent itself as radiation source by ion implanting 32P. Investigations of the surface properties were performed with special emphasis on activity retention. Clinical data of about 400 patients showed radioactive stents can suppress instent restenosis, but a so called edge effect appeared, which can be avoided by the new "drug eluting stents".

Golombeck, M.-A.; Heise, S.; Schloesser, K.; Schuessler, B.; Schweickert, H.

2003-05-01

87

a Gas Jet Target for Radioactive Ion Beam Experiments  

NASA Astrophysics Data System (ADS)

With the development of new radioactive ion beam (RIB) facilities such as FRIB, which will push measurements further away from stability, the need for improved RIB targets is more crucial than ever. Important scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on hydrogen and helium require targets that are dense, highly localized, and pure. To this end, the JENSA Collaboration led by the Colorado ol of Mines (CSM) is designing, building and testing a supersonic gas jet target for use at existing and future RIB facilities. The gas jet target allows for a high density and purity of target nuclei (such as 3He) within a highly confined region, without the use of windows or backing materials, and will also enable the use of state-of-the-art detection systems. The motivation, specifications and status of the CSM gas jet target system is discussed.

Chipps, K. A.; Greife, U.; Hager, U.; Sarazin, F.; Smith, M. S.; Bardayan, D. W.; Pain, S. D.; Schmitt, K. T.; Schatz, H.; Montes, F.; Meisel, Z.; Blackmon, J. C.; Linhardt, L. E.; Wiescher, M.; Couder, M.; Berg, G. P. A.; Robertson, D.; Vetter, P. A.; Lemut, A.; Erikson, L.

2013-03-01

88

Where metal ions bind in proteins.  

PubMed Central

The environments of metal ions (Li+, Na+, K+, Ag+, Cs+, Mg2+, Ca2+, Mn2+, Cu2+, Zn2+) in proteins and other metal-host molecules have been examined. Regardless of the metal and its precise pattern of ligation to the protein, there is a common qualitative feature to the binding site: the metal is ligated by a shell of hydrophilic atomic groups (containing oxygen, nitrogen, or sulfur atoms) and this hydrophilic shell is embedded within a larger shell of hydrophobic atomic groups (containing carbon atoms). That is, metals bind at centers of high hydrophobicity contrast. This qualitative observation can be described analytically by the hydrophobicity contrast function, C, evaluated from the structure. This function is large and positive for a sphere of hydrophilic atomic groups (characterized by atomic solvation parameters, delta sigma, having values less than 0) at the center of a larger sphere of hydrophobic atomic groups (characterized by delta sigma greater than 0). In the 23 metal-binding molecules we have examined, the maximum values of the contrast function lie near to observed metal binding sites. This suggests that the hydrophobicity contrast function may be useful for locating, characterizing, and designing metal binding sites in proteins. PMID:2377604

Yamashita, M M; Wesson, L; Eisenman, G; Eisenberg, D

1990-01-01

89

High-current pulsed ion source for metallic ions  

SciTech Connect

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

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

1981-03-01

90

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

91

Detection of Heavy Metal Ions in Drinking Water Using a  

E-print Network

Detection of Heavy Metal Ions in Drinking Water Using a High-Resolution Differential Surface-resolution differential surface plasmon resonance (SPR) sensor for heavy metal ion detection. The sensor surface using this sensor. Introduction The detection and quantification of heavy metal ions are important

Chen, Wilfred

92

A gas jet target for radioactive ion beam experiments  

SciTech Connect

New radioactive ion beam (RIB) facilities, like FRIB in the US or FAIR in Europe, will push further away from stability and enable the next generation of nuclear physics experiments. Thus, the need for improved RIB targets is more crucial than ever: developments in exotic beams should coincide with developments in targets for use with those beams, in order for nuclear physics to remain on the cutting edge. Of great importance to the future of RIB physics are scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on light targets such as hydrogen and helium. These measurements require targets that are dense, highly localized, and pure, and conventional targets often suffer too many drawbacks to allow for such experimental designs. Targets must also accommodate the use of large area, highly-segmented silicon detector arrays, high-efficiency gamma arrays, and novel heavy ion detectors to efficiently measure the reaction products. To address this issue, the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) Collaboration led by the Colorado School of Mines (CSM) is in the process of designing, building and testing a supersonic gas jet target for use at existing and future RIB facilities. The gas jet target provides a high density and high purity of target nuclei within a tightly confined region, without the use of windows or backing materials. The design also enables the use of multiple state-of-the-art detection systems.

Chipps, K. A.; Greife, U.; Hager, U.; Sarazin, F. [Colorado School of Mines, Golden, CO (United States); Bardayan, D. W.; Pain, S. D.; Schmitt, K. T.; Smith, M. S. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Blackmon, J. C.; Linhardt, L. E. [Louisiana State University, Baton Rouge, LA (United States); Browne, J.; Kontos, A.; Meisel, Z.; Montes, F.; Schatz, H. [National Superconducting Cyclotron Laboratory/Michigan State University, East Lansing, MI (United States); Couder, M.; Robertson, D.; Wiescher, M. [University of Notre Dame, Notre Dame, IN (United States); Erikson, L. E. [Pacific Northwest National Laboratory, Richland, WA (United States); Lemut, A. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); and others

2013-04-19

93

Production of light radioactive ion beams (RIB) using inverse kinematics  

NASA Astrophysics Data System (ADS)

At Nuclear Science Centre (NSC), New Delhi, we have implemented a facility to produce low energy light radioactive ion beams (RIBs) using (p,n) type of reactions in inverse kinematics. For this purpose primary beams from the 15-UD Pelletron accelerator impinged on a thin polypropylene foil mounted on a rotating/linearly moving target assembly. For efficiently separating the secondary beam from primary beam, the existing recoil mass spectrometer (RMS) HIRA was operated with new ion optics. Suitable hardware modifications were also made. Using this facility, we have extracted a 7Be beam of purity better than 99% and spot-size ˜4 mm in diameter. This 7Be beam has been utilized in a variety of experiments in the energy range of 15-22 MeV. Typical beam parameters are: intensity 10 4 pps, angular spread ±30 mrad and energy spread ±0.5 MeV. Development of appropriate detector setup/target arrangement were also made to perform these experiments. In this paper, we describe the implementation of this project.

Das, J. J.; Sugathan, P.; Madhavan, N.; Madhusudhana Rao, P. V.; Jhingan, A.; Varughese, T.; Barua, S.; Nath, S.; Sinha, A. K.; Kumar, B.; Zacharias, J.

2005-12-01

94

A gas jet target for radioactive ion beam experiments  

NASA Astrophysics Data System (ADS)

New radioactive ion beam (RIB) facilities, like FRIB in the US or FAIR in Europe, will push further away from stability and enable the next generation of nuclear physics experiments. Thus, the need for improved RIB targets is more crucial than ever: developments in exotic beams should coincide with developments in targets for use with those beams, in order for nuclear physics to remain on the cutting edge. Of great importance to the future of RIB physics are scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on light targets such as hydrogen and helium. These measurements require targets that are dense, highly localized, and pure, and conventional targets often suffer too many drawbacks to allow for such experimental designs. Targets must also accommodate the use of large area, highly-segmented silicon detector arrays, high-efficiency gamma arrays, and novel heavy ion detectors to efficiently measure the reaction products. To address this issue, the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) Collaboration led by the Colorado School of Mines (CSM) is in the process of designing, building and testing a supersonic gas jet target for use at existing and future RIB facilities. The gas jet target provides a high density and high purity of target nuclei within a tightly confined region, without the use of windows or backing materials. The design also enables the use of multiple state-of-the-art detection systems.

Chipps, K. A.; Bardayan, D. W.; Blackmon, J. C.; Browne, J.; Couder, M.; Erikson, L. E.; Greife, U.; Hager, U.; Kontos, A.; Lemut, A.; Linhardt, L. E.; Meisel, Z.; Montes, F.; Pain, S. D.; Robertson, D.; Sarazin, F.; Schatz, H.; Schmitt, K. T.; Smith, M. S.; Vetter, P.; Wiescher, M.

2013-04-01

95

Interplay of metal ions and urease  

PubMed Central

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

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

2009-01-01

96

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

PubMed Central

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 to 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.

2013-01-01

97

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

98

Study of Nuclear Reactions with 11C and 15O Radioactive Ion Beams  

SciTech Connect

Nuclear reaction study with radioactive ion beams is one of the most exciting research topics in modern nuclear physics. The development of radioactive ion beams has allowed nuclear scientists and engineers to explore many unknown exotic nuclei far from the valley of nuclear stability, and to further our understanding of the evolution of the universe. The recently developed radioactive ion beam facility at the Lawrence Berkeley National Laboratory's 88-inch cyclotron is denoted as BEARS and provides {sup 11}C, {sup 14}O and {sup 15}O radioactive ion beams of high quality. These moderate to high intensity, proton-rich radioactive ion beams have been used to explore the properties of unstable nuclei such as {sup 12}N and {sup 15}F. In this work, the proton capture reaction on {sup 11}C has been evaluated via the indirect d({sup 11}C, {sup 12}N)n transfer reaction using the inverse kinematics method coupled with the Asymptotic Normalization Coefficient (ANC) theoretical approach. The total effective {sup 12}N {yields} {sup 11}C+p ANC is found to be (C{sub eff}{sup 12{sub N}}){sup 2} = 1.83 {+-} 0.27 fm{sup -1}. With the high {sup 11}C beam intensity available, our experiment showed excellent agreement with theoretical predictions and previous experimental studies. This study also indirectly confirmed that the {sup 11}C(p,{gamma}) reaction is a key step in producing CNO nuclei in supermassive low-metallicity stars, bypassing the slow triple alpha process. The newly developed {sup 15}O radioactive ion beam at BEARS was used to study the poorly known level widths of {sup 16}F via the p({sup 15}O,{sup 15}O)p reaction. Among the nuclei in the A=16, T=1 isobaric triad, many states in {sup 16}N and {sup 16}O have been well established, but less has been reported on {sup 16}F. Four states of {sup 16}F below 1 MeV have been identified experimentally: 0{sup -}, 1{sup -}, 2{sup -}, and 3{sup -} (E{sub x} = 0.0, 0.19, 0.42, and 0.72 MeV, respectively). Our study utilized R-matrix analysis and found that the 0- state has a level width of 23.1 {+-} 2.2 keV, and that the broader 1- state has a width of 91.1 {+-} 9.9 keV. The level width of the 2{sup -} state is found to be 3.3 {+-} 0.6 keV which is much narrower than the compiled value of 40 {+-} 30 keV, while a width of 14.1 {+-} 1.7 keV for the 3{sup -} state is in good agreement with the reported value (< 15 keV). These experimental level widths of all four levels are also in accordance with theoretical predictions using single particle shell model calculation.

Lee, Dongwon

2007-05-14

99

Charge breeding of isotope on-line-created radioactive ions using an electron cyclotron resonance ion trap  

NASA Astrophysics Data System (ADS)

In the coming years huge ion-beam projects are foreseen. They deal with specific isotope on-line (ISOL) beams such as ISOL-created radioactive ions. The beam intensities are exceptionally high (>1012ions/s), the radioactive lifetimes are short (?1s), and the ion energy is very high (?150GeV/u). In general in order to minimize the size of the accelerator one needs highly charged ISOL ions and therefore charge breeders are a must. In contrast with the CERN system, utilizing a Penning trap and an electron-beam ion source charge breeder (where the maximum ion beam cannot exceed 106ions/s) the Grenoble group launched in 1995 an electron cyclotron resonance (ECR) system capable of storing 1012ions/s and delivering highly charged ISOL ions. In this article we show that this storage is possible for low-ion-energy ISOL ions following classical slowing down theory. In this case the injected ISOL ions are slowed down by ion-ion collisions which yield ion storage inside the ECR plasma, but also charge breeding by the energetic ECR electrons bombarding the slowed down ions.

Geller, R.; Lamy, T.; Sortais, P.

2006-03-01

100

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 ?m 2 at Ljubljana ion microprobe has been used to scan the surface of the pigments. PIXE mapping of Al K? map shows lateral distribution of the aluminum flakes, whereas the RBS slicing method reveals tomograms of the flakes in uppermost 7 ?m of the pigment layer. The series of point analysis aligned over the single flake reveal the flake angle in respect to the polymer matrix surface. The angular sensitivity is well below 1 angular degree.

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

2002-05-01

101

Incorporation of metal ions into polyimides  

NASA Technical Reports Server (NTRS)

The effects of the incorporation of metal ions into various polyimides on polyimide properties are investigated. Polyimide films derived from 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BDTA) 3,3'-diaminobenzophenone (m,m'-DABP), 4,4'-diaminobenzophenone (p,p'-DABP) or 4,4'-oxydianiline were prepared with the concurrent addition of approximately 20 metals in a variety of forms. In general, it is found that the films derived from BDTA + p,p'-DABP were brittle and of poor quality, with brittle films also produced in most of the BDTA + m, m'-DABP polyimides regardless of whether the added metal was hydrate or anhydrous. Thermomechanical analysis, torsional braid analysis, thermal gravimetric analysis, infrared spectral analysis and isothermal studies on many of the polyimide films produced indicate that the softening temperature is generally increased upon the addition of metal ions, at the expense of thermal stability, while no changes in chemical functionality are observed. The best system studied in regard to polymer property enhancement appears to be tri(acetylacetonato)aluminum(III) added to the m, m'-DABP polyamide, which has been found to exhibit four times the lap shear strength of the polyimide alone.

Taylor, L. T.; Carver, V. C.; Furtsch, T. A.; Saint Clair, A. K.

1980-01-01

102

Ionic Liquids as Extraction Media for Metal Ions  

NASA Astrophysics Data System (ADS)

In solvent extraction separation of metal ions, recently, many researchers have investigated possible use of hydrophobic ionic liquids as extraction media instead of organic solvents. Ionic liquids are salts of liquid state around room temperature and can act not only as solvents but also as ion-exchangers. Therefore, the extraction mechanism of metal ions into ionic liquids is complicated. This review presents current overview and perspective on evaluation of nature of hydrophobic ionic liquids as extraction media for metal ions.

Hirayama, Naoki

103

Metal Ion Levels in Maternal and Placental Blood After Metal-on-Metal Total Hip Arthroplasty.  

PubMed

There is concern regarding elevated metal ion levels in the blood during pregnancy and the potential fetal effects in women with metal-on-metal (MOM) implants. We obtained maternal and umbilical cord blood samples from 3 patients with a MOM hip arthroplasty and 7 control subjects without any metallic implants. Serum metal ion levels including chromium, cobalt, titanium, and nickel were tested using high-resolution sector-field inductively-coupled plasma-mass spectrometry. Mothers with MOM-bearing implants had significantly elevated levels of serum cobalt and chromium compared with control-group mothers, and umbilical cord blood from mothers with MOM implants also had significantly higher serum metal ion levels compared with control-group mothers. The results of this study show that circulating serum levels of metal ion degradation products from MOM bearings cross the placenta and expose the fetus to metal ions. However, the placenta exerts a modulatory effect on cord blood, resulting in decreased levels compared with maternal samples (approximately 15% of maternal chromium and 50% of maternal cobalt). Physicians and women of child-bearing age should be aware of this potential effect when considering the use of MOM-bearing implants. PMID:25490017

Novak, Clifford C; Hsu, Andrew R; Della Valle, Craig J; Skipor, Anastasia K; Campbell, Patricia; Amstutz, Harlan C; Jiranek, William A; Onyike, Aham; Pombar, Xavier F; Jacobs, Joshua J

2014-12-01

104

ION-EXCHANGE PROCESSES FOR REMOVING RADIOACTIVE CONTAMINATION FROM MILK  

Microsoft Academic Search

SUMMARY These studies on removing radioactive contamination from milk were carried on for the purpose of developing a feasible standby process for use in dairy plants in the event that radioactive fallout should reach hazardous levels. Current levels of all the radioactive contaminants are far below what is con- sidered hazardous levels; Iodine-131 is essentially undetectable in all milk supplies.

L. E. Edmondson

1964-01-01

105

A Gas Jet Target for Radioactive Ion Beam Experiments  

NASA Astrophysics Data System (ADS)

With the development of new radioactive ion beam (RIB) facilities such as FRIB, which will push further away from stability, the need for improved RIB targets is more crucial than ever. Important scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on hydrogen and helium require targets that are dense (˜1x10^19 nuclei/cm^2), highly localized, and pure. Conventional targets suffer too many drawbacks to allow for such measurements. Targets must also accommodate the use of novel detector arrays. To this end, a collaboration led by the Colorado School of Mines (CSM) is designing, building and testing a supersonic gas jet target for use at existing and future RIB facilities. The gas jet target allows for a high density and purity of target nuclei (such as ^3He) within a highly confined region, without the use of windows or backing materials, and will also enable the use of state-of-the-art detection systems. Motivation, specifications and status of the CSM gas jet target system will be discussed.

Chipps, K. A.

2011-10-01

106

Prototype negative-ion sources for radioactive ion-beam generation  

SciTech Connect

Radioactive ion beams (RIBs) of {sup 17}F and {sup 18}F are of interest for investigation of astrophysical phenomena such as the {open_quotes}hot{close_quotes} CNO cycle and the rp stellar nuclear synthesis processes. In order to generate useful beam intensities of atomic F{sup {minus}}, the species must be efficiently and expediently released from the target material, thermally dissociated from fluoride release products during transport to the ionization chamber of the ion source, and efficiently ionized in the source upon arrival. We have conceived and evaluated two prototype negative-ion sources for potential use for RIB generation: (1) a direct extraction source and (2) a kinetic-ejection source. Both sources utilize Cs vapor to enhance F{sup {minus}} formation. The mechanical design features, operational parameters, ionization efficiencies for forming atomic F{sup {minus}}, and delay times for transport of F and fluoride compounds for the respective sources are presented. The efficiency {eta} for formation and extraction of F{sup {minus}} for the direct extraction negative-ion source is found to be {eta}{approximately}1.0{percent} while the characteristic delay time {tau} for transport of F and fluorides through the source is, typically, {eta}{approximately}120thinsps; the analogous efficiencies and delay times for the kinetic ejection negative-ion source are, respectively: {eta}={approximately}3.2{percent} and {tau}={approximately}70thinsps. {copyright} {ital 1998 American Institute of Physics.}

Alton, G.D. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States); Welton, R.F.; Williams, C. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States); [Oak Ridge Institute of Science and Engineering, Oak Ridge, Tennessee 37831-6368 (United States); Cui, B. [China Institute of Atomic Energy, Beijing (China)] [China Institute of Atomic Energy, Beijing (China); Murray, S.N. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States)

1998-06-01

107

Accumulation of metal ions by pectinates  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

108

'Pseudotumour' invading the proximal femur with normal metal ions following metal on metal hip resurfacing.  

PubMed

A 75-year-old woman who had undergone hybrid metal-on-metal hip resurfacing 8?years earlier underwent revision arthroplasty because of hip, groin and lateral thigh pain. The main differential was aseptic loosening; however, serum cobalt and chromium levels were normal. Multiple imaging modalities revealed a periprosthetic, cystic soft tissue mass adjacent to the proximal femur. A large 'pseudotumour' with proximal femoral invasion was found at revision arthroplasty. We report the first finding of a 'pseudotumour' invading the proximal femur with normal metal ions following metal on metal hip resurfacing. PMID:25670783

Krishnan, Harry; Sugand, Kapil; Ali, Ibrahim; Smith, Jay

2015-01-01

109

Scientific program of the Radioactive Ion Beams Facility in Brasil (RIBRAS)  

Microsoft Academic Search

The RIBRAS facility (Radioactive Ion Beams in Brasil) is installed in connection with the 8MV Pelletron tandem of the University of São Paulo Physics Institute. It consists of two superconducting solenoids which focalize light radioactive secondary beams of low energy, produced by transfer reactions. Recent experimental results include the elastic scattering and transfer reactions of 6He halo nucleus on 9Be,

A. Lépine-Szily; R. Lichtenthäler; V. Guimarães; D. R. Mendes; P. N. de Faria; A. Barioni; E. A. Benjamim; K. C. C. Pires; V. Morcelle; R. Pampa Condori; M. C. Morais; P. Descouvemont; A. M. Moro; M. Rodríguez Gallardo; M. M. Assunção; J. A. Alcantara Nunez; J. M. B. Shorto; J. C. Zamora; E. Leistenschneider; C. E. F. Lima

2010-01-01

110

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

PubMed Central

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

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

2012-01-01

111

Constraints due to the production of radioactive ion beams in the SPIRAL project  

Microsoft Academic Search

The radioactive ion beams that will be delivered by the SPIRAL facility will be produced by the interaction of a stable high energy (95 MeV\\/A) and high intensity (2×1013 particle\\/s) primary ion beam delivered by the GANIL cyclotrons with a carbon target heated to 2000 °C. During this interaction, some radioactive atoms will be created and will diffuse out of

R. Leroy; Y. Huguet; P. Jardin; C. Marry; J. Y. Pacquet; A. C. C. Villari

1998-01-01

112

Securing the metal recycling chain for the steel industry by detecting orphan radioactive sources in scrap metal  

SciTech Connect

Experimental tests are reported for the detection of the heavy metal shielding of orphan sources hidden inside scrap metal by using a recently developed muon tomography system. Shielded sources do not trigger alarm in radiation portal commonly employed at the entrance of steel industry using scrap metal. Future systems integrating radiation portals with muon tomography inspection gates will substantially reduce the possibility of accidental melting of radioactive sources securing the use of recycled metal.

Pesente, S.; Benettoni, M.; Checchia, P.; Conti, E.; Gonella, F.; Nebbia, G. [INFN Sezione di Padova, via Marzolo 8, 35131 Padova Italy (Italy); Vanini, S.; Viesti, G.; Zumerle, G. [INFN Sezione di Padova, via Marzolo 8, 35131 Padova Italy (Italy); University of Padova and INFN Sezione di Padova, via Marzolo 8, 35131 Padova Italy (Italy); Bonomi, G.; Zenoni, A. [University of Brescia, via Branze 38, 25123 Brescia and INFN Sezione di Pavia, via Bassi 6, 27100 Pavia (Italy); Calvini, P.; Squarcia, S. [University of Genova and INFN Sezione di Genova, via Dodecaneso 33, 16146 Genova (Italy)

2010-08-04

113

Behavior of metal ions in bioelectrochemical systems: A review  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

114

Separation of traces of metal ions from sodium matrices  

NASA Technical Reports Server (NTRS)

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

Korkisch, J.; Orlandini, K. A.

1969-01-01

115

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

116

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

117

Boon and Bane of Metal Ions in Medicine  

Microsoft Academic Search

In biological systems metal ions promote responses that range from deficiency to toxicity. Some, such as iron and zinc, have a known optimal intake range for normal, healthy individuals. Metal ions contained within well-designed molecules already constitute a great boon for the medicinal pharmacopoeia. However, whether essential or not, the threshold for toxicity can be very low. One of the

Katherine H. Thompson; Chris Orvig

2003-01-01

118

Metal Ions: Supporting Actors in the Playbook of Small Ribozymes  

E-print Network

of large ribonucleoprotein complexes, many ribozymes can support catalysis without protein cofactors [16 Metal Ions: Supporting Actors in the Playbook of Small Ribozymes Alexander E. Johnson-Buck, Sarah 1. INTRODUCTION 176 2. INTERACTIONS BETWEEN METAL IONS AND SMALL RIBOZYMES 178 2.1. Modes

Walter, Nils G.

119

Oxidative mechanisms in the toxicity of metal ions.  

PubMed

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 oxygen species as superoxide ion, hydrogen peroxide, and hydroxyl radical. As a consequence, enhanced lipid peroxidation. DNA damage, and altered calcium and sulfhydryl homeostasis occur. Fenton-like reactions may be commonly associated with most membranous fractions including mitochondria, microsomes, and peroxisomes. Phagocytic cells may be another important source of reactive oxygen species in response to metal ions. Furthermore, various studies have suggested that the ability to generate reactive oxygen species by redox cycling quinones and related compounds may require metal ions. Recent studies have suggested that metal ions may enhance the production of tumor necrosis factor alpha (TNF alpha) and activate protein kinase C, as well as induce the production of stress proteins. Thus, some mechanisms associated with the toxicities of metal ions are very similar to the effects produced by many organic xenobiotics. Specific differences in the toxicities of metal ions may be related to differences in solubilities, absorbability, transport, chemical reactivity, and the complexes that are formed within the body. This review summarizes current studies that have been conducted with transition metal ions as well as lead, regarding the production of reactive oxygen species and oxidative tissue damage. PMID:7744317

Stohs, S J; Bagchi, D

1995-02-01

120

Electron Capture Dissociation of Trivalent Metal Ion-Peptide Complexes  

PubMed Central

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, resulting in similar electrochemical properties of these metal ions both in the peptide environment and in water. PMID:23283726

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

2013-01-01

121

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

Microsoft Academic Search

The hammerhead ribozyme is generally accepted as a well characterized metalloenzyme. However, the precise nature of the interactions of the RNA with metal ions remains to be fully defined. Examination of metal ion-catalyzed hammerhead reactions at limited concentrations of metal ions is useful for evaluation of the role of metal ions, as demonstrated in this study. At concentrations of Mn2+

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

2002-01-01

122

Metal Ion Sensors Based on DNAzymes and Related DNA Molecules  

PubMed Central

Metal ion sensors are an important yet challenging field in analytical chemistry. Despite much effort, only a limited number of metal ion sensors are available for practical use because sensor design is often a trial-and-error-dependent process. DNAzyme-based sensors, in contrast, can be developed through a systematic selection that is generalizable for a wide range of metal ions. Here, we summarize recent progress in the design of DNAzyme-based fluorescent, colorimetric, and electrochemical sensors for metal ions, such as Pb2+, Cu2+, Hg2+, and UO22+ In addition, we also describe metal ion sensors based on related DNA molecules, including T-T or C-C mismatches and G-quadruplexes. PMID:21370984

Kong, Rong-Mei

2011-01-01

123

Fulvic acid: modifier of metal-ion chemistry  

SciTech Connect

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

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

1982-01-01

124

DNA as Sensors and Imaging Agents for Metal Ions  

PubMed Central

Increasing interests in detecting metal ions in many chemical and biomedical fields have created demands for developing sensors and imaging agents for metal ions with high sensitivity and selectivity. This review covers recent progress in DNA-based sensors and imaging agents for metal ions. Through both combinatorial selection and rational design, a number of metal ion-dependent DNAzymes and metal ion-binding DNA structures that can selectively recognize specific metal ions have been obtained. By attaching these DNA molecules with signal reporters such as fluorophores, chromophores, electrochemical tags, and Raman tags, a number of DNA-based sensors for both diamagnetic and paramagnetic metal ions have been developed for fluorescent, colorimetric, electrochemical, and surface Raman detections. These sensors are highly sensitive (with detection limit down to 11 ppt) and selective (with selectivity up to millions-fold) toward specific metal ions. In addition, through further development to simplify the operation, such as the use of “dipstick tests”, portable fluorometers, computer-readable discs, and widely available glucose meters, these sensors have been applied for on-site and real-time environmental monitoring and point-of-care medical diagnostics. The use of these sensors for in situ cellular imaging has also been reported. The generality of the combinatorial selection to obtain DNAzymes for almost any metal ion in any oxidation state, and the ease of modification of the DNA with different signal reporters make DNA an emerging and promising class of molecules for metal ion sensing and imaging in many fields of applications. PMID:24359450

Xiang, Yu

2014-01-01

125

Determination of noble metals in Savannah River Site high-level radioactive sludge  

Microsoft Academic Search

High-level radioactive sludge at the Savannah River Site (SRS) will be processed at the Defense Waste Processing Facility (DWPF) into durable borosilicate glass wasteforms. The sludges are analyzed for elemental content before processing to ensure compatibility with the glass-making processes. Noble metal fission products in sludge, can under certain conditions, cause problems in the glass melter. Therefore, reliable noble metal

C. J. Coleman; W. F. Kinard; N. E. Bibler; D. F. Bickford; W. G. Ramsey

1990-01-01

126

The first external loop of the metal ion transporter DCT1 is involved in metal ion binding and specificity  

E-print Network

The first external loop of the metal ion transporter DCT1 is involved in metal ion binding mutant smf1 cannot grow on medium containing EGTA. Expression of Smf1p or the mammalian transporter DCT1 to analyze the properties of mutations in the predicted external loop I of DCT1. The sensitivity

Nelson, Nathan

127

Aspects on metal ion distribution models in pulp washing simulation  

Microsoft Academic Search

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

Karin Mattsson; Gunnar Eriksson; Urban Grén; Krister Ström

2007-01-01

128

Reusable chelating resins concentrate metal ions from highly dilute solutions  

NASA Technical Reports Server (NTRS)

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

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

1966-01-01

129

Constraints due to the production of radioactive ion beams in the SPIRAL project  

NASA Astrophysics Data System (ADS)

The radioactive ion beams that will be delivered by the SPIRAL facility will be produced by the interaction of a stable high energy (95 MeV/A) and high intensity (2×1013 particle/s) primary ion beam delivered by the GANIL cyclotrons with a carbon target heated to 2000 °C. During this interaction, some radioactive atoms will be created and will diffuse out of the target before entering into an electron cyclotron resonance (ECR) ion source where they will be ionized and extracted. The production of radioactive ion beams with this method implies high radiation fields that activate and can damage materials located in the neighborhood of the target. Therefore, the production system which is composed of the permanent magnet ECR ion source coupled to a graphite target will be changed after two weeks of irradiation. As this ensemble will be very radioactive, this operation has to be supervised by remote control. The radiation levels around the target-ion source system and a detailed description of the different precautions that have been taken for safety and for prevention of contamination and irradiation are presented.

Leroy, R.; Huguet, Y.; Jardin, P.; Marry, C.; Pacquet, J. Y.; Villari, A. C. C.

1998-02-01

130

Proceedings of the workshop on prospects for research with radioactive beams from heavy ion accelerators  

SciTech Connect

The SuperHILAC Users Executive Committee organized a workshop on Prospects for Research with Radioactive Beams from Heavy Ion Accelerators. The main purpose of the workshop was to bring together a diverse group of scientists who had already done experients with radioactive beams or were interested in their use in the future. The topics of the talks ranged from general nuclear physics, astrophysics, production of radioactive beams and high energy projectile fragmentation to biomedical applications. This publication contains the abstracts of the talks given at the workshop and copies of the viewgraphs as they were supplied to the editor.

Nitschke, J.M. (ed.)

1984-04-01

131

Ion-exchange material and method of storing radioactive wastes  

DOEpatents

A new cation exchanger is a modified tobermorite containing aluminum isomorphously substituted for silicon and containing sodium or potassium. The exchanger is selective for lead, rubidium, cobalt, and cadmium and is selective for cesium over calcium or sodium. The tobermorites are compatible with cement and are useful for the long-term fixation and storage of radioactive nuclear wastes.

Komarneni, S.; Roy, D.M.

1983-10-31

132

Detection of toxic metal ions with near-infrared compounds  

NASA Astrophysics Data System (ADS)

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

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

1994-10-01

133

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

134

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

135

Applications of radioactive ion beams to solid-state physics  

Microsoft Academic Search

:   Radioactive atoms have been used in solid-state physics and in material science for many decades. Besides their classical\\u000a application as tracer for diffusion studies, nuclear techniques such as Mößbauer spectroscopy, perturbed angular correlation,\\u000a ?-NMR, and emission channeling have used nuclear properties (via hyperfine interactions or emitted ?- or ?-particles) to gain\\u000a microscopical information on the structural and dynamical properties

M. Deicher

2002-01-01

136

Studies of sorbent\\/ion-exchange materials for the removal of radioactive strontium from liquid radioactive waste and high hardness groundwaters  

Microsoft Academic Search

Different sorbents were studied in terms of their full-scale applicability for radioactive strontium removal in low-level liquid radioactive waste (LLRW) management. The following types of sorbent\\/ion-exchange materials were investigated: natural zeolite–clinoptilolite, modified natural clinoptilolite, synthetic zeolites, new synthetic crystalline materials selective to strontium, ion-exchange resins, and modified fiber sorbents. Simulated solutions for experimental tests were prepared according to the composition

Dmitry V Marinin; Garrett N Brown

2000-01-01

137

MODELING AN ION EXCHANGE PROCESS FOR CESIUM REMOVAL FROM ALKALINE RADIOACTIVE WASTE SOLUTIONS  

SciTech Connect

The performance of spherical Resorcinol-Formaldehyde ion-exchange resin for the removal of cesium from alkaline radioactive waste solutions has been investigated through computer modeling. Cesium adsorption isotherms were obtained by fitting experimental data using a thermodynamic framework. Results show that ion-exchange is an efficient method for cesium removal from highly alkaline radioactive waste solutions. On average, two 1300 liter columns operating in series are able to treat 690,000 liters of waste with an initial cesium concentration of 0.09 mM in 11 days achieving a decontamination factor of over 50,000. The study also tested the sensitivity of ion-exchange column performance to variations in flow rate, temperature and column dimensions. Modeling results can be used to optimize design of the ion exchange system.

Smith, F; Luther Hamm, L; Sebastian Aleman, S; Johnston Michael, J

2008-08-26

138

Upgrade status and plans at the Holifield Radioactive Ion Beam Facility  

NASA Astrophysics Data System (ADS)

The Holifield Radioactive Ion Beam Facility (HRIBF) is a national user facility dedicated to nuclear structure and astrophysics research with Radioactive Ion Beams (RIBs) using the Isotope Separator On-Line (ISOL) technique. HRIBF also maintains a vibrant development program for ISOL targets, ion sources and diagnostics. As a bridge to RIA, HRIBF continues to expand its technology. Presently, a $4.75M High Power Target Laboratory (HPTL) is being constructed to provide a facility for testing new targets, target geometries, ion sources and beam preparation techniques. HPTL will ultimately be co-located with a second RIB production system (IRIS2). An external axial injection system for the driver cyclotron, ORIC, is planned to provide higher beam intensities, reduce machine activation and eliminate cathode lifetime limitations. A multi-channel residual gas BPM is under development for measuring intensity and position of the driver beam. RIB production via electron-induced photofission is also being explored to attain higher intensities.

Tatum, Brian Alan

2005-12-01

139

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

SciTech Connect

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

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

1999-12-01

140

Metal Ion Substrate Inhibition of Ferrochelatase*S?  

PubMed Central

Ferrochelatase catalyzes the insertion of ferrous iron into protoporphyrin IX to form heme. Robust kinetic analyses of the reaction mechanism are complicated by the instability of ferrous iron in aqueous solution, particularly at alkaline pH values. At pH 7.00 the half-life for spontaneous oxidation of ferrous ion is approximately 2 min in the absence of metal complexing additives, which is sufficient for direct comparisons of alternative metal ion substrates with iron. These analyses reveal that purified recombinant ferrochelatase from both murine and yeast sources inserts not only ferrous iron but also divalent cobalt, zinc, nickel, and copper into protoporphyrin IX to form the corresponding metalloporphyrins but with considerable mechanistic variability. Ferrous iron is the preferred metal ion substrate in terms of apparent kcat and is also the only metal ion substrate not subject to severe substrate inhibition. Substrate inhibition occurs in the order Cu2+ > Zn2+ > Co2+ > Ni2+ and can be alleviated by the addition of metal complexing agents such as ?-mercaptoethanol or imidazole to the reaction buffer. These data indicate the presence of two catalytically significant metal ion binding sites that may coordinately regulate a selective processivity for the various potential metal ion substrates. PMID:18593702

Hunter, Gregory A.; Sampson, Matthew P.; Ferreira, Gloria C.

2008-01-01

141

Metal ion removal from aqueous solution using physic seed hull.  

PubMed

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

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

2010-07-15

142

Catalytic metal ions and enzymatic processing of DNA and RNA.  

PubMed

Conspectus Two-metal-ion-dependent nucleases cleave the phosphodiester bonds of nucleic acids via the two-metal-ion (2M) mechanism. Several high-resolution X-ray structures portraying the two-metal-aided catalytic site, together with mutagenesis and kinetics studies, have demonstrated a functional role of the ions for catalysis in numerous metallonucleases. Overall, the experimental data confirm the general mechanistic hypothesis for 2M-aided phosphoryl transfer originally reported by Steitz and Steitz ( Proc. Natl. Acad. Sci. U.S.A. 1993 , 90 ( 14 ), 6498 - 6502 ). This seminal paper proposed that one metal ion favors the formation of the nucleophile, while the nearby second metal ion facilitates leaving group departure during RNA hydrolysis. Both metals were suggested to stabilize the enzymatic transition state. Nevertheless, static X-ray structures alone cannot exhaustively unravel how the two ions execute their functional role along the enzymatic reaction during processing of DNA or RNA strands when moving from reactants to products, passing through metastable intermediates and high-energy transition states. In this Account, we discuss the role of multiscale molecular simulations in further disclosing mechanistic insights of 2M-aided catalysis for two prototypical enzymatic targets for drug discovery, namely, ribonuclease H (RNase H) and type II topoisomerase (topoII). In both examples, first-principles molecular simulations, integrated with structural data, emphasize a cooperative motion of the bimetal motif during catalysis. The coordinated motion of both ions is crucial for maintaining a flexible metal-centered structural architecture exquisitely tailored to accommodate the DNA or RNA sugar-phosphate backbone during phosphodiester bond cleavage. Furthermore, our analysis of RNase H and the N-terminal domain (PAN) of influenza polymerase shows that classical molecular dynamics simulations coupled with enhanced sampling techniques have contributed to describe the modulatory effect of metal ion concentration and metal uptake on the 2M mechanism and efficiency. These aspects all point to the emerging and intriguing role of additional adjacent ions potentially involved in the modulation of phosphoryl transfer reactions and enzymatic turnover in 2M-catalysis, as recently observed experimentally in polymerase ? and homing endonuclease I-DmoI. These computational results, integrated with experimental findings, describe and reinforce the nascent concept of a functional and cooperative dynamics of the catalytic metal ions during the 2M-dependent enzymatic processing of DNA and RNA. Encouraged by the insights provided by computational approaches, we foresee further experiments that will feature the functional and joint dynamics of the catalytic metal ions for nucleic acid processing. This could impact the de novo design of artificial metallonucleases and the rational design of potent metal-chelating inhibitors of pharmaceutically relevant enzymes. PMID:25590654

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

2015-02-17

143

Extracting metal ions with diphosphonic acid, or derivative thereof  

DOEpatents

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

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

1994-07-26

144

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

145

Ion plating seals microcracks or porous metal components  

NASA Technical Reports Server (NTRS)

Description of ion plating process is given. Advantage of this process is that any plating metal or alloy can be selected, whereas, for conventional welding, material selection is limited by compatability.

Spalvins, T.; Buckley, D. H.; Brainard, W. A.

1972-01-01

146

Metallic glass as a temperature sensor during ion plating  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

147

Metallic glass as a temperature sensor during ion plating  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

148

Exploiting neutron-rich radioactive ion beams to constrain the symmetry energy  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet were used to measure the free neutrons and heavy charged particles from the radioactive ion beam induced 32Mg+9Be reaction. The fragmentation reaction was simulated with the constrained molecular dynamics model (CoMD), which demonstrated that the of the heavy fragments and free neutron multiplicities were observables sensitive to the density dependence of the symmetry energy at subsaturation densities. Through comparison of these simulations with the experimental data, constraints on the density dependence of the symmetry energy were extracted. The advantage of radioactive ion beams as a probe of the symmetry energy is demonstrated through examination of CoMD calculations for stable and radioactive-beam-induced reactions.

Kohley, Z.; Christian, G.; Baumann, T.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Jones, M.; Smith, J. K.; Snyder, J.; Spyrou, A.; Thoennessen, M.

2013-10-01

149

Smart textile device using ion polymer metal compound.  

PubMed

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

Nakamura, Taro; Ihara, Tadashi

2013-01-01

150

Michigan state upgrade to produce intense radioactive ion beams by fragmentation technique  

SciTech Connect

This article describes the planned upgrading of accelerator facilities to produce intense radioactive ion beams, by a fragmentation technique, for experimental simulation of nucleosynthesis in novas and supernovas. (AIP) {ital 1997 American Institute of Physics.} {copyright} {ital 1997} {ital American Institute of Physics}

Lubkin, G.B. [Physics Today, American Center for Physics, One Physics Ellipse, College Park, Maryland 20740-3843 (United States)

1997-05-01

151

Measuring neutrino mass with radioactive ions in a storage ring  

NASA Astrophysics Data System (ADS)

We propose a method to measure the neutrino mass kinematically using beams of ions which undergo beta decay. The idea is to tune the ion beam momentum so that in most decays, the electron is forward moving with respect to the beam, and only in decays near the endpoint is the electron moving backwards. Then, by counting the backward moving electrons one can observe the effect of neutrino mass on the beta spectrum close to the endpoint. In order to reach sensitivities for m? < 0.2 eV, it is necessary to control the ion momentum with a precision better than ?p/p < 10-5, identify suitable nuclei with low Q-values (in the few to ten keV range), and one must be able to observe at least Script O(1018) decays.

Lindroos, Mats; McElrath, Bob; Orme, Christopher; Schwetz, Thomas

2010-01-01

152

Measuring Neutrino Mass with Radioactive Ions in a Storage Ring  

NASA Astrophysics Data System (ADS)

A method to measure the neutrino mass kinematically using beams of ions which undergo beta decay is proposed. The idea is to tune the ion beam momentum so that in most decays, the electron is forward moving with respect to the beam, and only in decays near the endpoint is the electron moving backwards. By counting the backward moving electrons one can observe the effect of neutrino mass on the beta spectrum close to the endpoint. In order to reach sensitivities for m?<0.2 eV, it is necessary to control the ion momentum with a precision better than ?p/p<10-5, identify suitable nuclei with low Q-values (in the few to ten keV range), and one must be able to observe at least O(1018) decays.

Lindroos, Mats; McElrath, Bob; Orme, Christopher; Schwetz, Thomas

2010-03-01

153

Measuring neutrino mass with radioactive ions in a storage ring  

NASA Astrophysics Data System (ADS)

We propose a method to measure the neutrino mass kinematically using beams of ions which undergo beta decay. The idea is to tune the ion beam momentum so that in most decays, the electron is forward moving with respect to the beam, and only in decays near the endpoint is the electron moving backwards. Then, by counting the backward moving electrons one can observe the effect of neutrino mass on the beta spectrum close to the endpoint. In order to reach sensitivities for m ? <0.2 eV, it is necessary to control the ion momentum with a precision better than ? p/ p<10-5, identify suitable nuclei with low Q-values (in the few to ten keV range), and one must be able to observe at least mathcal{O}(10^{18}) decays.

Lindroos, Mats; McElrath, Bob; Orme, Christopher; Schwetz, Thomas

2009-12-01

154

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

155

Detection of Metallic Compounds in Rocket Plumes Using Ion Probes  

NASA Technical Reports Server (NTRS)

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

Dunn, Robert W.

1998-01-01

156

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

E-print Network

Structure of the Alkali-metal-atom-Strontium molecular ions: towards photoassociation and formation polarizability, of molecular ions composed of one alkali-metal atom and a Strontium ion are determined and a Strontium ion are discussed, as well as the formation of stable molecular ions. PACS numbers: 31.15.AR,31

157

Synergistic Catalysis of Dimetilan Hydrolysis by Metal Ions and  

E-print Network

Synergistic Catalysis of Dimetilan Hydrolysis by Metal Ions and Organic Ligands C H I N G - H U A H, The Johns Hopkins University, Baltimore, Maryland 21218 Hydrolysis of the insecticide dimetilan, which ion-organic ligandsynergisticeffectsonthedegradationofagrochemicals. Dimetilan hydrolysis is strongly

Huang, Ching-Hua

158

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

159

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

160

Metal ion deposition from ionized mangetron sputtering discharge  

Microsoft Academic Search

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

S. M. Rossnagel; J. Hopwood

1994-01-01

161

Surface Precipitation of Hydrolyzable Metal Ions on Oxide Surfaces  

E-print Network

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

Sparks, Donald L.

162

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

163

Neutralization by Metal Ions of the Toxicity of Sodium Selenide  

PubMed Central

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

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

2013-01-01

164

RATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS  

EPA Science Inventory

An enormous amount of radioactive and toxic chemical waste remains at over one hundred sites managed by the Department of Energy. Despite the investment of large sums, major goals associated with the cleanup remain unmet. It is our thesis that economically practical accomplishmen...

165

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 × 10 16 and 1 × 10 17 ions/cm 2, 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 × 10 16 ions/cm 2) 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

166

Removal of metal ions from aqueous solution  

DOEpatents

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

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

1990-11-13

167

Removal of metal ions from aqueous solution  

DOEpatents

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

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

1990-01-01

168

Effect of Metal Ions on Melanin – Local Anaesthetic Drug Complexes  

PubMed Central

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

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

2003-01-01

169

Analysis of metallic pigments by ion microbeam  

Microsoft Academic Search

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

P. Pelicon; M. Klanjsek-Gunde; M. Kunaver; J. Simcic; M. Budnar

2002-01-01

170

Metal ion release after total hip replacement.  

PubMed

The concentration of cobalt (Co), chromium (Cr), molybdenum (Mo), nickel (Ni), iron (Fe) and zinc (Zn) was measured using neutron activation analysis in tissue taken from an 81 year old female at necropsy. The patient had bilateral cobalt chromium molybdenum (Co-Cr-Mo) total hip replacements: one, a metal-on-metal had been in place for 14 years, the other a metal-on-plastic for 5.5 years. Although the metal-on-metal side had become painful, the patient remained active until she died. The measurements indicated that the concentrations of Co and Cr in the lung, kidney, liver and spleen were up to fifty times "Standard Man" values. High values occurred also in the urine and in the hair. The tissue adjacent to the metal-on-metal joint was heavily laden with metal wear debris, whereas that adjacent to the metal-on-plastic joint was relatively uncontaminated. The concentration varied with distance from the implant. Co predominated in the urine, whereas Cr predominated near the implants. The existence of such high levels, especially in the organs, is a possible cause for concern. PMID:7470573

Dobbs, H S; Minski, M J

1980-10-01

171

Complexation-induced supramolecular assembly drives metal-ion extraction.  

PubMed

Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts. PMID:25169678

Ellis, Ross J; Meridiano, Yannick; Muller, Julie; Berthon, Laurence; Guilbaud, Philippe; Zorz, Nicole; Antonio, Mark R; Demars, Thomas; Zemb, Thomas

2014-09-26

172

Transport of radioactive ion beams and related safety issues: The (132)Sn(+) case study.  

PubMed

The transport of intense radioactive ion beam currents requires a careful design in order to limit the beam losses, the contamination and thus the dose rates. Some investigations based on numerical models and calculations have been performed in the framework of the SPIRAL 2 project to evaluate the performance of a low energy beam transport line located between the isotope separation on line (ISOL) production cell and the experiment areas. The paper presents the results of the transverse phase-space analysis, the beam losses assessment, the resulting contamination, and radioactivity levels. They show that reasonable beam transmission, emittance growth, and dose rates can be achieved considering the current standards. PMID:25554283

Osswald, F; Bouquerel, E; Boutin, D; Dinkov, A; Kazarinov, N; Perrot, L; Sellam, A

2014-12-01

173

Transport of radioactive ion beams and related safety issues: The 132Sn+ case study  

NASA Astrophysics Data System (ADS)

The transport of intense radioactive ion beam currents requires a careful design in order to limit the beam losses, the contamination and thus the dose rates. Some investigations based on numerical models and calculations have been performed in the framework of the SPIRAL 2 project to evaluate the performance of a low energy beam transport line located between the isotope separation on line (ISOL) production cell and the experiment areas. The paper presents the results of the transverse phase-space analysis, the beam losses assessment, the resulting contamination, and radioactivity levels. They show that reasonable beam transmission, emittance growth, and dose rates can be achieved considering the current standards.

Osswald, F.; Bouquerel, E.; Boutin, D.; Dinkov, A.; Kazarinov, N.; Perrot, L.; Sellam, A.

2014-12-01

174

Ion source developments for the production of radioactive isotope beams at TRIUMF  

SciTech Connect

At the ISAC facility at TRIUMF radioactive ions are produced by bombarding solid targets with up to 100 ?A of 500 MeV protons. The reaction products have to diffuse out of the hot target into an ion source. Normally, singly charged ions are extracted. They can be transported either directly to experiments or via an ECR charge state breeder to a post accelerator. Several different types of ion sources have to be used in order to deliver a large variety of rare isotope beams. At ISAC those are surface ion sources, forced electron beam arc discharge (FEBIAD) ion sources and resonant laser ionization sources. Recent development activities concentrated on increasing the selectivity for the ionization to suppress isobaric contamination in the beam. Therefore, a surface ion rejecting resonant laser ionization source (SIRLIS) has been developed to suppress ions from surface ionization. For the FEBIAD ion source a cold transfer line has been introduced to prevent less volatile components from reaching the ion source.

Ames, F., E-mail: ames@triumf.ca; Bricault, P.; Heggen, H.; Kunz, P.; Lassen, J.; Mjøs, A.; Raeder, S.; Teigelhöfer, A. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T2A3 (Canada)] [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T2A3 (Canada)

2014-02-15

175

Cellular responses to metal ions released from implants.  

PubMed

In the process of calcified tissue formation, cells secrete a protein-rich matrix into which they add a metal ion that nucleates in the presence of phosphorus to form an inorganic salt (usually calcium hydroxyapatite). Cellular and tissue responses to metal ions-released from implants, for example-can therefore be considered from the perspective of how cells handle calcium ions. A critical factor in determining cellular toxicity will be free ion concentrations and the competitive interactions that occur in a physicochemical manner. Three of the parameters used to assess the biocompatibility of implant materials are (1) the ability to influence mitotic activity, (2) intercellular adhesion, and (3) promotion of cell death. A spectrum of responses to free intracellular calcium ions can be identified, ranging from presence of the ion being essential for cell division through to an excess of the free ion that results in cell death (apoptosis). In between these extremes, cells may become postmitotic and express phenotypic variations as they adapt to their environment and establish equilibrium to maintain intracellular calcium homeostasis. The response of cells to implants can be linked to ions released and interactions between these and other ions and/or molecules present in the tissues, similar to the manner in which cells handle calcium ions. PMID:24914916

Kardos, Thomas B

2014-06-01

176

Means for obtaining a metal ion beam from a heavy-ion cyclotron source  

DOEpatents

A description is given of a modification to a cyclotron ion source used in producing a high intensity metal ion beam. A small amount of an inert support gas maintains the usual plasma arc, except that it is necessary for the support gas to have a heavy mass, e.g., xenon or krypton as opposed to neon. A plate, fabricated from the metal (or anything that can be sputtered) to be ionized, is mounted on the back wall of the ion source arc chamber and is bombarded by returning energetic low-charged gas ions that fail to cross the initial accelerating gap between the ion source and the accelerating electrode. Some of the atoms that are dislodged from the plate by the returning gas ions become ionized and are extracted as a useful beam of heavy ions. (auth)

Hudson, E.D.; Mallory, M.L.

1975-08-01

177

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

PubMed Central

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

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

2008-01-01

178

Layered metal sulfides: Exceptionally selective agents for radioactive strontium removal  

PubMed Central

In this article, we report the family of robust layered sulfides K2xMnxSn3-xS6 (x = 0.5–0.95) (KMS-1). These materials feature hexagonal [MnxSn3-xS6]2x? slabs of the CdI2 type and contain highly mobile K+ ions in their interlayer space that are easily exchangeable with other cations and particularly strontium. KMS-1 display outstanding preference for strontium ions in highly alkaline solutions containing extremely large excess of sodium cations as well as in acidic environment where most alternative adsorbents with oxygen ligands are nearly inactive. The implication of these results is that simple layered sulfides should be considered for the efficient remediation of certain nuclear wastes. PMID:18316731

Manos, Manolis J.; Ding, Nan; Kanatzidis, Mercouri G.

2008-01-01

179

Fluorescent carbon nanoparticles for the fluorescent detection of metal ions.  

PubMed

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

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

2015-01-15

180

Rapid in vitro screening of drug-metal ion interactions.  

PubMed

ABSTRACT The toxic side effects of synthetic drugs may, in part, be arising due to their interactions with essential metal ions, especially when the metal ions are administered along with the drug as mineral supplements. In this paper we report the feasibility of establishing such drug-metal ion interactions through in vitro spectrophotometric studies, which are rapid and can be used for routine screening prior to clinical studies. The interaction of the drugs levothyroxine and ranitidine with eight metal ions, copper(II), chromium(III), molybdenum(VI), magnesium(II), calcium(II), iron(II), manganese(II), and zinc(II), commonly used in mineral supplements, was verified through in vitro UV-visible spectrophotometric studies. The experiments were carried out at the physiological pH values 1.5, 7.4, and 8.0 and the concentrations of the drugs and mineral supplements used were comparable to those in their usual doses. These studies indicated interaction between ranitidine and calcium(II), magnesium(II), and iron(II) ions and between levothyroxine and copper(II) and iron(II) ions. A comparison of the results with those reported from clinical studies demonstrated the efficacy of this method. PMID:20020882

Sridevi, N; Yusuff, K K Mohammed

2007-01-01

181

RADIOACTIVE MATERIAL SHIPPING PACKAGINGS AND METAL TO METAL SEALS FOUND IN THE CLOSURES OF CONTAINMENT VESSELS INCORPORATING CONE SEAL CLOSURES  

SciTech Connect

The containment vessels for the Model 9975 radioactive material shipping packaging employ a cone-seal closure. The possibility of a metal-to-metal seal forming between the mating conical surfaces, independent of the elastomer seals, has been raised. It was postulated that such an occurrence would compromise the containment vessel hydrostatic and leakage tests. The possibility of formation of such a seal has been investigated by testing and by structural and statistical analyses. The results of the testing and the statistical analysis demonstrate and procedural changes ensure that hydrostatic proof and annual leakage testing can be accomplished to the appropriate standards.

Loftin, B; Glenn Abramczyk, G; Allen Smith, A

2007-06-06

182

Membranes Remove Metal Ions Fron Industrial Liquids  

NASA Technical Reports Server (NTRS)

Use of membrane films affords convenient and economical alternative for removing and recovering metal cations present in low concentrations from large quantities of liquid solutions. Possible applications of membrane films include use in analytical chemistry for determination of small amounts of toxic metallic impurities in lakes, streams, and municipal effluents. Also suitable for use as absorber of certain pollutant gases and odors present in confined areas.

Hsu, W. P. L.; May, C.

1983-01-01

183

Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.  

PubMed

Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory. PMID:24702119

Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan

2014-04-29

184

Charge state breeding for the acceleration of radioactive ions at TRIUMF  

SciTech Connect

A 14.5 GHz electron cyclotron resonance ion source (PHOENIX from Pantechnik) has been set up at the Isotope Separation and ACceleration (ISAC) facility at TRIUMF for the charge state breeding of radioactive ions. After extensive testing and optimization on a test bench it has been moved on-line and put into operation. During a first test in 2008 a beam of {sup 80}Rb{sup 14+} was successfully created from {sup 80}Rb{sup 1+} and accelerated by the ISAC postaccelerator. Further tests with different stable and radioactive isotopes from the ISAC on-line sources and from a test source with stable Cs have been carried out. Until now an efficiency of 1.4% for {sup 124}Cs{sup 20+} has been obtained.

Ames, F.; Baartman, R.; Bricault, P.; Jayamanna, K.; McDonald, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Lamy, T. [LPSC, CNRS/IN2P3, UJF, 53 Av. des Martyres, 38026 Grenoble (France)

2010-02-15

185

Study of resonance states in 12N using a radioactive ion beam of 11C  

NASA Astrophysics Data System (ADS)

Resonance states in 12N were studied by using the resonance elastic scattering of 11C+p with a low-energy radioactive ion beam of 11C at 3.5 MeV/nucleon and a thick (CH2)n target. The 11C beam was separated by a newly installed CNS radioactive ion beam separator (CRIB). The energy spectrum of recoil protons was measured at laboratory scattering angles around ?LAB=0° to identify resonance states in 12N. The spin-parity values of J?=3- and (2)+ have been determined for the levels at the excitation energies of Ex=3.1 and 3.6 MeV in 12N, respectively, suggesting a small contribution of the 3.1-MeV level to the 11C(p, ?)12N stellar reaction.

Teranishi, T.; Kubono, S.; Shimoura, S.; Notani, M.; Yanagisawa, Y.; Michimasa, S.; Ue, K.; Iwasaki, H.; Kurokawa, M.; Satou, Y.; Morikawa, T.; Saito, A.; Baba, H.; Lee, J. H.; Lee, C. S.; Fülöp, Zs.; Kato, S.

2003-03-01

186

A Negative-Surface Ionization for Generation of Halogen Radioactive Ion Beams  

SciTech Connect

A simple and efficient negative surface ionization source has been designed, fabricated and initially tested for on-line generation of radioactive ion beams of the halogens (Cl, Br, I, and At) for use in the nuclear-structure and nuclear-astrophysics research programs at the Holifield Radioactive Ion Beam Facility. The source utilizes a solid, spherical geometry LaB{sub 6} surface ionizer for forming highly electronegative atoms and molecules. Despite its widely publicized propensity for being easily poisoned, no evidences of this effect were experienced during testing of the source. Nominal efficiencies of 15% for Br{sup {minus}} beam generation were obtained during off-line evaluation of the source with AlBr3 feed material when account is taken of the fractional dissociation of the molecule. Principles of operation, design features, operational parameter data, initial performance results, and beam quality data (emittance) are presented in this article.

Zaim, H.

2001-04-16

187

Multiple Metal Binding Domains Enhance the Zn(II) Selectivity of the Divalent Metal Ion Transporter AztA  

E-print Network

, Pb, Hg, and As, do not accumulate inside cells. The heavy metal ion-transporting CPxMultiple Metal Binding Domains Enhance the Zn(II) Selectivity of the Divalent Metal Ion Transporter 3, 2007; ReVised Manuscript ReceiVed July 17, 2007 ABSTRACT: Transition metal-transporting P1B

Scott, Robert A.

188

Biomimetic metal-sorbing vesicles for continuous extraction of heavy metal ions from dilute solution  

SciTech Connect

Biomimetic vesicle media which can selectivity extract and concentrate heavy metals (e.g., Pb{sup 2+}) from dilute solutions of 5 ppm and less have been prepared. At a concentration of only 1% 2/v, these non-covalently assembled, unilamellar, surfactant vesicles provide approximately 1,000m{sup 2} of exposed membrane surface area per liter of suspension which gives rise to very rapid rates of metal ion extraction. To facilitate the selective transport of heavy metal ions through the ion impermeable vesicle wall, the vesicles are doped with lipophilic ionophores, both natural and synthetic. In addition, the metal chelating agent, nitrolotriacetate, is encapsulated in the aqueous vesicle core to provide the driving force for metal ion uptake and concentration. Concentration factors in excess of 1000 fold have been observed. Metal-sorbing surfactant vesicles measuring approximately 100 nm in diameter are stable and have been tested in a bench-scale metal ion extraction process where the vesicles are recircled continuously through a hollow-fiber ultrafiltration cartridge.

Monbouquette, H.G.; Chang, D.; Walsh, A.J.; van Zanten, J.H. [Univ. of California, Los Angeles, CA (United States)

1993-12-31

189

Detection of Heavy Metal Ions in Water by High-Resolution Surface Plasmon Resonance  

E-print Network

Detection of Heavy Metal Ions in Water by High-Resolution Surface Plasmon Resonance Spectroscopy voltammetry (ASV) capability has been demonstrated for detecting heavy metal ions in water. Metal ions in water from part-per-million to sub-part-per-billion levels with good linearity. Heavy metal poisoning

Zhang, Yanchao

190

Diagnostics of hollow cathode discharge metal ion lasers  

NASA Astrophysics Data System (ADS)

Lasing properties of active media in sputtered hollow cathode discharge (HCD) He-Cu lasers operating on 780.8 nm transition have been investigated for several HC configurations. Direct measurements of small-signal gain and its spatial distribution have proved that a segmented hollow cathode discharge (SHCD) is the most efficient in achieving laser action on metal ions excited by thermal energy charge-transfer reaction. Results obtained for He-Cu lasers indicate that the observed linear dependency of gain on discharge current can be explained by limited flow of metal atoms into the region of laser generation and probably are valid for all kind of sputtered metal ion lasers oscillating on UV and IR transitions. The possibility of obtaining continuous or long-pulse laser operation in far UV range is also discussed. A new method of measuring diffusion coefficients of metal atoms in noble gases in sputtered HCD lasers is presented.

Adamowicz, Tadeusz M.

1997-08-01

191

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 6 weeks 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 6 weeks. This translated to a decline of approximately 80% from the starting value after 6 weeks and a decline of approximately 90% after 12 weeks post-revision. The rate of decline for both Co and Cr was significantly faster during the first 6 weeks (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

2013-09-01

192

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

193

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

194

Electronic energy-density effects in ion tracks of metals  

Microsoft Academic Search

High resolution Auger-electron spectroscopy has been applied to the interaction of swift heavy ions with atomically clean metallic solids. Spectra have been taken for fast projectile electrons and for charge-state equilibrated ions at normal incidence on microcrystalline beryllium samples, Al(100) single crystals and several metallic glasses (Al87La7Ni5Zr1, Ni78B14Si8, Co66Si16B12Fe4Mo2). From the energy shift and from the Auger-line width we have

F. Staufenbiel; G. Schiwietz; K. Czerski; M. Roth; P. L. Grande

2005-01-01

195

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

196

Strong cation···? interactions promote the capture of metal ions within metal-seamed nanocapsule.  

PubMed

Thallium ions are transported to the interior of gallium-seamed pyrogallol[4]arene nanocapsules. In comparison to the capture of Cs ions, the extent of which depends on the type and position of the anion employed in the cesium salt, the enhanced strength of Tl···? vs Cs···? interactions facilitates permanent entrapment of Tl(+) ions on the capsule interior. "Stitching-up" the capsule seam with a tertiary metal (Zn, Rb, or K) affords new trimetallic nanocapsules in solid state. PMID:25405777

Kumari, Harshita; Jin, Ping; Teat, Simon J; Barnes, Charles L; Dalgarno, Scott J; Atwood, Jerry L

2014-12-10

197

Data mining of metal ion environments present in protein structures  

PubMed Central

Analysis of metal-protein interaction distances, coordination numbers, B-factors (displacement parameters), and occupancies of metal binding sites in protein structures determined by X-ray crystallography and deposited in the PDB shows many unusual values and unexpected correlations. By measuring the frequency of each amino acid in metal ion binding sites, the positive or negative preferences of each residue for each type of cation were identified. Our approach may be used for fast identification of metal-binding structural motifs that cannot be identified on the basis of sequence similarity alone. The analysis compares data derived separately from high and medium resolution structures from the PDB with those from very high resolution small-molecule structures in the Cambridge Structural Database (CSD). For high resolution protein structures, the distribution of metal-protein or metal-water interaction distances agrees quite well with data from CSD, but the distribution is unrealistically wide for medium (2.0 – 2.5 Å) resolution data. Our analysis of cation B-factors versus average B-factors of atoms in the cation environment reveals substantial numbers of structures contain either an incorrect metal ion assignment or an unusual coordination pattern. Correlation between data resolution and completeness of the metal coordination spheres is also found. PMID:18614239

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

2010-01-01

198

In vivo liberation of silver ions from metallic silver surfaces  

Microsoft Academic Search

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

Gorm Danscher; Linda Jansons Locht

2010-01-01

199

Engineered allosteric ribozymes that respond to specific divalent metal ions  

Microsoft Academic Search

In vitro selection was used to isolate five classes of allosteric hammerhead ribozymes that are triggered by binding to certain divalent metal ion effectors. Each of these ribozyme classes are similarly activated by Mn21 ,F e21 ,C o21 ,N i21 ,Z n21 and Cd21, but their allo- steric binding sites reject other divalent metals such as Mg21 ,C a21 and

Maris Zivarts; Yong Liu; Ronald R. Breaker

2005-01-01

200

Smart responsive microcapsules capable of recognizing heavy metal ions.  

PubMed

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

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

2010-09-15

201

Ion exchange columns for selective removal of cesium from aqueous radioactive waste using hydrous crystalline silico-titanates  

E-print Network

ION EXCHANGE COLUMNS FOR SELECTIVE REMOVAL OF CESIUM FROM AQUEOUS RADIOACTIVE WASTE USING HYDROUS CRYSTALLINE SILICO-TITANATES A Thesis by DAVID MICHAEL RICCI Submitted to the Office of Graduate Studies of Texas ARM University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1995 Major Subject: Chemical Engineering ION EXCHANGE COLUMNS FOR SELECTIVE REMOVAL OF CESIUM FROM AQUEOUS RADIOACTIVE WASTE USING HYDROUS CRYSTALLINE SILICO-TITANATES A Thesis...

Ricci, David Michael

2012-06-07

202

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

203

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

204

Superconductivity in Metal-mixed Ion-Implanted Polymer Films  

E-print Network

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

A. P. Micolich; E. Tavenner; B. J. Powell; A. R. Hamilton; M. T. Curry; R. E. Giedd; P. Meredith

2005-09-11

205

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

206

Evaluation of the electrorefining technique for the processing of radioactive scrap metals  

SciTech Connect

This report presents the results of a literature study performed to identify applications of the electrorefining technique to the decontamination of radioactively-contaminated scrap metal (RSM). Upon the completion of the literature search and the review of numerous references, it was concluded that there were applications of this technique that were appropriate for the decontamination of some types of RSM, especially when the desired product is a pure elemental metal of high purity. It was also concluded that this technique was not well-suited for the decontamination of RSM stainless steels and other alloys, when it was desired that the metallurgical characteristics of the alloy be present in the decontaminated product.

Kessinger, G.F.

1993-10-01

207

Uptake of Metal Ions by Rhizopus arrhizus Biomass  

PubMed Central

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

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

1984-01-01

208

Metallic ions in cometary comae and plasma tails  

NASA Astrophysics Data System (ADS)

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

Ip, W.-H.; Axford, W. I.

1986-06-01

209

The metal vapor vacuum arc (MEVVA) high current ion source  

SciTech Connect

An ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ions are extracted. Beams of a variety of ions have been produced, ranging from lithium up to uranium. At an extraction voltage of 25 kV we've measured an ion beam current of over 1 Ampere, with over 550 ema of the beam in an emittance of 0.07..pi.. cm. mradians (normalized). The ion charge state distribution varies with cathode material and with arc power; for uranium a typical distribution is peaked at U/sup 5 +/, with up to 40% of the beam current in this charge state.

Brown, I.G.

1985-10-01

210

Metal vapor vacuum arc (MEVVA) high current ion source  

SciTech Connect

An ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ions are extracted. Beams of a variety of ions have been produced, ranging from lithium up to uranium. At an extraction voltage of 25 kV we've measured an ion beam current of over 1 Ampere, with over 550 ema of the beam in an emittance of 0.07..pi.. cm. mradians (normalized). The ion charge state distribution varies with cathode material and with arc power; for uranium a typical distribution is peaked at U/sup 5 +/, with up to 40% of the beam current in this charge state. 27 refs., 10 figs.

Brown, I.G.

1985-05-01

211

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

212

Cooling of short-lived, radioactive, highly charged ions with the TITAN cooler Penning trap. Status and perspectives  

NASA Astrophysics Data System (ADS)

TITAN is an on-line facility dedicated to precision experiments with short-lived radioactive isotopes, in particular mass measurements. The achievable resolution on mass measurement, which depends on the excitation time, is limited by the half life of the radioactive ion. One way to bypass this is by increasing the charge state of the ion of interest. TITAN has the unique capability of charge-breeding radioactive ions using an electron-beam ion trap (EBIT) in combination with Penning trap mass spectrometry. However, the breeding process leads to an increase in energy spread, ? E, which in turn negatively influences the mass uncertainty. We report on the development of a cooler Penning trap which aims at reducing the energy spread of the highly charged ions prior to injection into the precision mass measurement trap. Electron and proton cooling will be tested as possible routes. Mass selective cooling techniques are also envisioned.

Simon, V. V.; Delheij, P.; Dilling, J.; Ke, Z.; Shi, W.; Gwinner, G.

2011-07-01

213

PARTITIONING-SEPARATION OF METAL IONS USING HETEROCYCLIC LIGANDS  

Microsoft Academic Search

Some guidelines are proposed for the effective design of heterocylic ligands for partitioning because there is no doubt that the correct design of a molecular extractant is required for the effective separation of metal ions such as actinides(III) from lanthanides(III). Heterocyclic ligands with aromatic ring systems have a rich chemistry, which is only now becoming sufficiently well understood in relation

Michael J. Hudson; Michael G. B. Drew; Peter B. Iveson; Charles Madic; Mark L. Russell

214

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....

215

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

216

Laser-driven ion sources for metal ion implantation for the reduction of dry friction  

SciTech Connect

The anomalously high ion currents and very high ionization levels of laser-produced plasmas give laser-driven ion sources significant advantages over conventional ion sources. In particular, laser-driven ion sources should provide higher currents of metal ions at lower cost, for implantation into solids in order to improve their material properties such as friction. The energy and charge distributions for Pb and Sn ions produced by ablation of solid targets with {approx}25 J, {approx}300 ps iodine laser pulses, resulting in up to 48-times ionized MeV ions, as well as the optimization of focus position, are presented. Implantation of these ions into Ck-45 steel, without electrostatic acceleration, produced profiles with two regions. Almost all of the ions were implanted in a near surface region a few nm deep. However, a small but significant number of ions were implanted as deep as could be measured with Rutherford backscattering (RBS), here 150 nm for Sn and 250 nm for Pb. For the implanted ion densities and profiles achieved, no change in the coefficient of friction was measured for either ion.

Boody, F. P. [Fachhochschule Regensburg, Seybothstrasse 2, 93053 Regensburg (Germany); Juha, L. [Fachhochschule Regensburg, Seybothstrasse 2, 93053 Regensburg (Germany) and Institute of Physics, Academy Sciences of the Czech Republic, Na Slovance 2, 180 40 Prague 8 (Czech Republic); Kralikova, B.; Krasa, J.; Laska, L.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Straka, P. [Institute of Physics, Academy Sciences of the Czech Republic, Na Slovance 2, 180 40 Prague 8 (Czech Republic); Perina, V. [Nuclear Physics Institute, Academy Sciences of the Czech Republic, 25068 Rez (Czech Republic); Woryna, E. [Institute of Plasma Physics and Laser Microfusion, 00908 Warsaw (Poland); Giersch, D. [BMW AG, 80788 Munich (Germany); Hoepfl, R. [Fachhochschule Deggendorf, Franz-Josef-Strauss-Str. 7, 94469 Deggendorf (Germany); Kelly, J. C.; Hora, H. [University of New South Wales, Sydney 2052 (Australia)

1997-04-15

217

Ion exchangers as adsorbents for removing metals from aquatic media.  

PubMed

A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals. PMID:24292693

Khan, Meraj A; Bushra, Rani; Ahmad, Anees; Nabi, Syed A; Khan, Dilwar A; Akhtar, Arshia

2014-02-01

218

Development and properties of crystalline silicotitanate (CST) ion exchangers for radioactive waste applications  

SciTech Connect

Crystalline silicotitanates (CSTs) are a new class of ion exchangers that were jointly invented by researchers at Sandia National Laboratories and Texas A&M University. One particular CST, known as TAM-5, is remarkable for its ability to separate parts-per-million concentrations of cesium from highly alkaline solutions (pH> 14) containing high sodium concentrations (>5M). It is also highly effective for removing cesium from neutral and acidic solutions, and for removing strontium from basic and neutral solutions. Cesium isotopes are fission products that account for a large portion of the radioactivity in waste streams generated during weapons material production. Tests performed at numerous locations with early lab-scale TAM-5 samples established the material as a leading candidate for treating radioactive waste volumes such as those found at the Hanford site in Washington. Thus Sandia developed a Cooperative Research and Development Agreement (CRADA) partnership with UOP, a world leader in developing, commercializing, and supplying adsorbents and associated process technology to commercialize and further develop the material. CSTs are now commercially available from UOP in a powder (UOP IONSIV{reg_sign} IE-910 ion exchanger) and granular form suitable for column ion exchange operations (UOP IONSIV{reg_sign} IE-911 ion exchanger). These materials exhibit a high capacity for cesium in a wide variety of solutions of interest to the Department of Energy, and they are chemically, thermally, and radiation stable. They have performed well in tests at numerous sites with actual radioactive waste solutions, and are being demonstrated in the 100,000 liter Cesium Removal Demonstration taking place at Oak Ridge National Laboratory with Melton Valley Storage Tank waste. It has been estimated that applying CSTs to the Hanford cleanup alone will result in a savings of more than $300 million over baseline technologies.

Miller, J.E.; Brown, N.E.

1997-04-01

219

Nuclear Structure Studies with Radioactive Ion Beams in the Mass A = 80 Region  

SciTech Connect

An experimental program to measure spectroscopic properties of neutron-rich nuclei in the A = 80 region is underway at the Holifield Radioactive Ion Beam Facility. Our approach has been to get a comprehensive picture of the shell structure in this region by studying a series of properties of low lying states (E(2{sup +}), B(E2), g-factors and quadrupole moments). The beams, instrumentation and techniques developed specifically for this purpose have allowed us to systematically study the behavior of these observables along isotopic and isotonic chains using both stable and radioactive nuclei under almost identical experimental conditions. We have developed many techniques and detectors for in-beam gamma spectroscopy with radioactive ion beams. Most of the detectors can be used individually or in combination. Generally these detector systems have very large efficiencies. We give examples of their use from three recent experiments; namely, Coulomb excitation of n-rich nuclei along the N = 50 shell closure, the static quadrupole moment of the first 2{sup +} in {sup 78}Ge and g-factor measurements of n-rich isotopes near N = 50.

Galindo-Uribarri, A.; Beene, J. R.; Lagergren, K. B.; Mueller, P. E.; Radford, D. C.; Stracener, D. W.; Varner, R. L.; Yu, C.-H. [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 (United States); Padilla-Rodal, E. [Instituto de Ciencias Nucleares, UNAM, Mexico City 04510 (Mexico); Batchelder, J. C. [UNIRIB, Oak Ridge Associated Universities, Oak Ridge TN 37831 (United States); Urrego-Blanco, J. P. [Department of Physics and Astronomy, University of Tennessee, Knoxville TN 37996 (United States)

2009-03-10

220

Nuclear Structure Studies with Radioactive Ion Beams in the Mass A = 80 Region  

SciTech Connect

An experimental program to measure spectroscopic properties of neutron-rich nuclei in the A = 80 region is underway at the Holifield Radioactive Ion Beam Facility. Our approach has been to get a comprehensive picture of the shell structure in this region by studying a series of properties of low lying states (E (2+), B (E2), g-factors and quadrupole moments). The beams, instrumentation and techniques developed specifically for this purpose have allowed us to systematically study the behavior of these observables along isotopic and isotonic chains using both stable and radioactive nuclei under almost identical experimental conditions. We have developed many techniques and detectors for in-beam gamma spectroscopy and decay studies with radioactive ion beams. Most of the detectors can be used individually or in combination. Generally these detector systems have very large efficiencies. We give examples of their use from three recent experiments; namely, Coulomb excitation of n-rich nuclei along the N = 50 shell closure, the static quadrupole moment of the first 2+ in 78Ge and g-factor measurements of n-rich isotopes near N = 50.

Galindo-Uribarri, Alfredo {nmn} [ORNL; Padilla, E. [ORNL/Instituto de Ciencias Nucleares, UNAM, Mexico; Batchelder, J. C. [Oak Ridge Associated Universities (ORAU); Beene, James R [ORNL; Lagergren, Karin B [ORNL; Mueller, Paul Edward [ORNL; Radford, David C [ORNL; Stracener, Daniel W [ORNL; Urrego-Blanco, J. P. [University of Tennessee, Knoxville (UTK); Varner Jr, Robert L [ORNL; Yu, Chang-Hong [ORNL

2009-01-01

221

Recoil separators for radiative capture using radioactive ion beams. Recent advances and detection techniques  

NASA Astrophysics Data System (ADS)

Radiative capture reactions involving the fusion of hydrogen or helium are ubiquitous in the stellar history of the universe, and are some of the most important reactions in the processes that govern nucleosynthesis and energy generation in both static and explosive scenarios. However, radiative capture reactions pose some of the most difficult experimental challenges due to extremely small cross sections. With the advent of recoil separators and techniques in inverse kinematics, it is now possible to measure radiative capture reactions on very short-lived radioactive nuclei, and in the presence of high experimental backgrounds. In this paper we review the experimental needs for making measurements of astrophysical importance on radiative capture reactions. We also review some of the important historical advances in the field of recoil separators as well as describe current techniques and performance milestones, including descriptions of some of the separators most recently working at radioactive ion beam facilities, such as DRAGON at TRIUMF and the DRS at the Holifield Radioactive Ion Beam Facility. We will also summarize some of the scientific highlight measurements at the RIB facilities.

Ruiz, Chris; Greife, Uwe; Hager, Ulrike

2014-06-01

222

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

223

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

224

Metal ion influence on eumelanin fluorescence and structure  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

225

Solution NMR Refinement of a Metal Ion Bound Protein Using Metal Ion Inclusive Restrained Molecular Dynamics Methods  

PubMed Central

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

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

2013-01-01

226

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

DOEpatents

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

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

1987-06-02

227

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

228

Radioactive ion beam transportation for the fundamental symmetry study with laser-trapped atoms  

SciTech Connect

The search for the violation of the fundamental symmetry in a radioactive atom is the promising candidate for precision tests of the standard model and its possible extensions. The subtle signal arising from the symmetry violation is enhanced in heavy atoms, such as a francium (Fr). To realize high precision measurements, a large amount of radioactive isotopes is required. The Fr is produced via a nuclear fusion reaction using a melted gold target with a {sup 18}O primary beam at Cyclotron and Radioisotope Center, Tohoku University. The maximum extraction efficiency of the Fr ion was achieved at approximately 35%. The beam line consists of an electrostatic deflector, three electrostatic quadrupole triplets to the measurement area at 10 m away from the reaction point, and several beam diagnosis systems. We optimized parameters of the beam line.

Arikawa, Hiroshi, E-mail: arikawa@cyric.tohoku.ac.jp; Ando, S.; Aoki, T.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kawamura, H.; Kato, K.; Kato, T.; Uchiyama, A.; Sakemi, Y. [Cyclotron and Radioisotope Center, Tohoku University, Miyagi 980-8578 (Japan)] [Cyclotron and Radioisotope Center, Tohoku University, Miyagi 980-8578 (Japan); Aoki, T. [Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902 (Japan)] [Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902 (Japan); Furukawa, T. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan)] [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Hatakeyama, A. [Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo 184-8588 (Japan)] [Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo 184-8588 (Japan); Hatanaka, K.; Yoshida, H. P. [Research Center for Nuclear Physics, Osaka University, Osaka 606-8502 (Japan)] [Research Center for Nuclear Physics, Osaka University, Osaka 606-8502 (Japan); Imai, K. [Advanced Science Research Center, Japan Atomic Energy Agency, Ibaraki 319-1184 (Japan)] [Advanced Science Research Center, Japan Atomic Energy Agency, Ibaraki 319-1184 (Japan); and others

2014-02-15

229

Peptide immobilisation on porous silicon surface for metal ions detection  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

230

Peptide immobilisation on porous silicon surface for metal ions detection  

PubMed Central

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

2011-01-01

231

Investigation of a tin liquid metal ion source  

NASA Astrophysics Data System (ADS)

In view of its importance in materials research, tin is a metal worth studying in a liquid metal ion source configuration, even if results complement or extend previous work. This is the more so if the new work corrects misconceptions of the past and adds to current thinking. We, therefore, prepared a Sn liquid metal ion source employing a Ni needle to anchor the liquid, cone-shaped, emitter. Source properties, such as the current-voltage curve, the mass spectra of the beam and the energy spread of the main ionic species, were studied in detail. The mass spectra show a considerable amount of Sn clusters, apart from the dominant species, Sn+ and Sn++. The source was stable down to 1-?A emission current, corresponding to an energy spread for the singly charged ions of 7 eV. Theoretical arguments, involving the peak energy deficit of the ion-energy distribution, strongly suggest that both Sn+ and Sn++ are emitted by direct field evaporation from the liquid surface. The same conclusion is reached from a careful examination of the beam mass spectra of the source.

Bischoff, L.; Akhmadaliev, C.; Mair, A. W. R.; Mair, G. L. R.; Ganetsos, T.; Aidinis, C. J.

232

New Catalytic DNA Biosensors for Radionuclides and Metal ion  

SciTech Connect

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

Yi Lu

2008-03-01

233

Polymer filtration systems for dilute metal ion recovery  

SciTech Connect

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

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

1998-12-01

234

Ion beam mixing of metal/fluoropolymer interfaces  

SciTech Connect

Ion beam mixing of metals and polymers with very low dielectric constants such as Teflon can provide many applications in the area of electronic materials. This work is a study of the 'mixing' effect of 50 keV nitrogen implanted thin metal layers on Teflon PTFE (polytetrafluoroethylene) substrates. RBS analysis shows that the distribution of thin layers of copper and chromium (approximately 300-400 A thick) through the implant layer of the Teflon depends on the reactivity of the metal. As the implant fluence is increased, the distribution of metal atoms in the polymer matrix becomes concentrated over smaller ranges near the bottom of the implant layer. In situ RGA analysis during the implantation shows the liberation of an abundance of fluorine in many different forms. This is supported by results from a NRA experiment that shows the non-uniform concentration profile of fluorine throughout the implant layer. During the implantation process, the fluorine is released through the incident ion track leaving a carbon and metal rich region near the surface of the implant layer. The fluorine density increases with depth through the implant layer making a smooth transition to the undamaged bulk Teflon below. Low dielectric materials with highly conductive surfaces, such as this one, may provide an opportunity for a broad range of new microelectronic applications.

Dennis, D. L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Giedd, R. E. [Southwest Missouri State University, Springfield, Missouri 65804 (United States); Wang, Y. Q. [Center for Interfacial Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Glass, G. A. [Acadiana Research Laboratory, University of Southwestern Louisiana, Lafayette, Louisiana 70504 (United States)

1999-06-10

235

Ion beam mixing of metal/fluoropolymer interfaces  

SciTech Connect

Ion beam mixing of metals and polymers with very low dielectric constants such as Teflon can provide many applications in the area of electronic materials. This work is a study of the {open_quotes}mixing{close_quotes} effect of 50 keV nitrogen implanted thin metal layers on Teflon PTFE (polytetrafluoroethylene) substrates. RBS analysis shows that the distribution of thin layers of copper and chromium (approximately 300-400 {Angstrom} thick) through the implant layer of the Teflon depends on the reactivity of the metal. As the implant fluence is increased, the distribution of metal atoms in the polymer matrix becomes concentrated over smaller ranges near the bottom of the implant layer. {ital In situ} RGA analysis during the implantation shows the liberation of an abundance of fluorine in many different forms. This is supported by results from a NRA experiment that shows the non-uniform concentration profile of fluorine throughout the implant layer. During the implantation process, the fluorine is released through the incident ion track leaving a carbon and metal rich region near the surface of the implant layer. The fluorine density increases with depth through the implant layer making a smooth transition to the undamaged bulk Teflon below. Low dielectric materials with highly conductive surfaces, such as this one, may provide an opportunity for a broad range of new microelectronic applications. {copyright} {ital 1999 American Institute of Physics.}

Dennis, D.L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Giedd, R.E. [Southwest Missouri State University, Springfield, Missouri 65804 (United States); Wang, Y.Q. [Center for Interfacial Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Glass, G.A. [Acadiana Research Laboratory, University of Southwestern Louisiana, Lafayette, Louisiana 70504 (United States)

1999-06-01

236

hammerhead ribozyme nor to these metal ions. Any RNA for which an assay is avail-  

E-print Network

hammerhead ribozyme nor to these metal ions. Any RNA for which an assay is avail- able to monitor metal exchange can, in principle, be used. Folded RNAs provide complex surfaces to which different metal unique metal ion sites on these complex folded RNA structures. REFERENCES AND NOTES

Tsien, Roger Y.

237

Novel synthetic phytochelatin-based capacitive biosensor for heavy metal ion detection  

E-print Network

Novel synthetic phytochelatin-based capacitive biosensor for heavy metal ion detection Ibolya on synthetic phytochelatins for sensitive detection of heavy metals is described. Synthetic phytochelatin (Glu: Biosensors; Heavy metals; Phytochelatins; Capacitance 1. Introduction Evolution of our society has lead

Chen, Wilfred

238

The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum  

NASA Technical Reports Server (NTRS)

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

Danford, M. D.

1993-01-01

239

The beam diagnostic instruments in Beijing radioactive ion-beam facilities isotope separator on-line  

SciTech Connect

The beam diagnostic instruments for Beijing Radioactive Ion-beam Facilities Isotope Separator On-Line are introduced [B. Q. Cui, Z. H. Peng, Y. J. Ma, R. G. Ma, B. Tang, T. Zhang, and W. S. Jiang, Nucl. Instrum. Methods 266, 4113 (2008); T. J. Zhang, X. L. Guan, and B. Q. Cui, in Proceedings of APAC 2004, Gyeongju, Korea, 2004, http://www.jacow.org , p. 267]. For low intensity ion beam [30–300 keV/1 pA–10 ?A], the beam profile monitor, the emittance measurement unit, and the analyzing slit will be installed. For the primary proton beam [100 MeV/200 ?A], the beam profile scanner will be installed. For identification of the nuclide, a beam identification unit will be installed. The details of prototype of the beam diagnostic units and some experiment results will be described in this article.

Ma, Y., E-mail: yjma@ciae.ac.cn; Cui, B.; Ma, R.; Tang, B.; Chen, L.; Huang, Q.; Jiang, W. [China Institute of Atomic Energy, Beijing 102413 (China)] [China Institute of Atomic Energy, Beijing 102413 (China)

2014-02-15

240

The beam diagnostic instruments in Beijing radioactive ion-beam facilities isotope separator on-line.  

PubMed

The beam diagnostic instruments for Beijing Radioactive Ion-beam Facilities Isotope Separator On-Line are introduced [B. Q. Cui, Z. H. Peng, Y. J. Ma, R. G. Ma, B. Tang, T. Zhang, and W. S. Jiang, Nucl. Instrum. Methods 266, 4113 (2008); T. J. Zhang, X. L. Guan, and B. Q. Cui, in Proceedings of APAC 2004, Gyeongju, Korea, 2004, http://www.jacow.org, p. 267]. For low intensity ion beam [30-300 keV/1 pA-10 ?A], the beam profile monitor, the emittance measurement unit, and the analyzing slit will be installed. For the primary proton beam [100 MeV/200 ?A], the beam profile scanner will be installed. For identification of the nuclide, a beam identification unit will be installed. The details of prototype of the beam diagnostic units and some experiment results will be described in this article. PMID:24593450

Ma, Y; Cui, B; Ma, R; Tang, B; Chen, L; Huang, Q; Jiang, W

2014-02-01

241

The beam diagnostic instruments in Beijing radioactive ion-beam facilities isotope separator on-line  

NASA Astrophysics Data System (ADS)

The beam diagnostic instruments for Beijing Radioactive Ion-beam Facilities Isotope Separator On-Line are introduced [B. Q. Cui, Z. H. Peng, Y. J. Ma, R. G. Ma, B. Tang, T. Zhang, and W. S. Jiang, Nucl. Instrum. Methods 266, 4113 (2008); T. J. Zhang, X. L. Guan, and B. Q. Cui, in Proceedings of APAC 2004, Gyeongju, Korea, 2004, http://www.jacow.org, p. 267]. For low intensity ion beam [30-300 keV/1 pA-10 ?A], the beam profile monitor, the emittance measurement unit, and the analyzing slit will be installed. For the primary proton beam [100 MeV/200 ?A], the beam profile scanner will be installed. For identification of the nuclide, a beam identification unit will be installed. The details of prototype of the beam diagnostic units and some experiment results will be described in this article.

Ma, Y.; Cui, B.; Ma, R.; Tang, B.; Chen, L.; Huang, Q.; Jiang, W.

2014-02-01

242

Charge state breeding of radioactive ions with an electron cyclotron resonance ion source at TRIUMF  

SciTech Connect

Efficient primary ion sources at ISOL facilities normally produce singly charged ions. This limits the usable mass range for postacceleration due to the A/Q acceptance of the accelerator. At the ISAC facility at TRIUMF an A/Q below 7 is desired to avoid further stripping. Thus, charge state breeding is necessary if higher masses are to be accelerated. A 14 GHz ECRIS 'PHOENIX' booster has been chosen as a breeder. In order to investigate and optimize its performance under ISAC conditions it has been set up at a test bench equipped with a standard ISAC target-ion-source to produce singly charged ions. A series of measurements has been performed with the noble gases Ar, Kr, and Xe. Efficiencies of more than 6% in the maximum of the charge state distribution after mass separation have been obtained and the emittance of the extracted beam and breeding times have been measured. This article gives a status report on the ongoing measurements.

Ames, F.; Baartman, R.; Bricault, P.; Jayamanna, K.; McDonald, M.; Olivo, M.; Schmor, P.; Yuan, D.H.L.; Lamy, T. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada); LPSC, UJF-IN2P3-CNRS, 53 Avenue des Martyrs, 38026 Grenoble (France)

2006-03-15

243

Production of radioactive Ag ion beams with a chemically selective laser ion source  

NASA Astrophysics Data System (ADS)

We have developed a chemically selective laser ion source at the CERN-ISOLDE facility in order to study neutron-rich Ag nuclides. A pulsed laser system with high repetition rate has been used based on high-power copper-vapour pump lasers and dye lasers. With this source significant reductions of the isobaric background has been achieved.

Jading, Y.; Catherall, R.; Jokinen, A.; Jonsson, O. C.; Kugler, E.; Lettry, J.; Ravn, H. L.; Tengblad, O.; Kautzsch, T.; Klöckl, I.; Kratz, K.-L.; Scheerer, F.; Fedoseyev, V. N.; Mishin, V. I.; van Duppen, P.; Wöhr, A.; Walters, W. B.

1996-04-01

244

Interactions of metal ions with ? synuclein and amyloid ? peptides  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

245

Nanomagnetic chelators for removal of toxic metal ions  

NASA Astrophysics Data System (ADS)

Ethylenediamine trtraaceteic acid (EDTA) functionalized Fe3O4 nanomagnetic chelators (NMCs) were synthesized by co-precipitation method followed by in-situ grafting of EDTA. XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. Surface functionalization of Fe3O4 with EDTA was evident from FTIR spectroscopy, TGA analysis and zeta-potential measurement. These NMCs exhibit superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. It has been observed that NMCs have strong tendency for adsorption of various toxic metal ions (Ni2+, Cr3+, Cu2+, Cd2+, Co2+ and Pb2+) from waste-water. Furthermore, these magnetic chelators can be used as highly efficient separable and reusable material for removal of toxic metal ions.

Singh, Sarika; Barick, K. C.; Bahadur, D.

2013-02-01

246

Pollution of the Begej Canal sediment--metals, radioactivity and toxicity assessment.  

PubMed

The Begej Canal is one among a large number of canals in Vojvodina (Northern Province of Serbia and Montenegro). The paper describes a study of metal and radioactivity contamination of the Begej Canal sediment. It is also concerned with the evaluation of sediment acute toxicity based on standard test species Daphnia magna and simultaneously extracted metals and acid volatile sulfides. The quality of sediment was assessed according to Dutch standards, but the results were also compared with some Canadian and USEPA (United States Environmental Protection Agency) guidelines for sediment quality. The results showed severe pollution with chromium, copper, cadmium and zinc, whereby the anthropogenic origin of these contaminants was indicated. The tests of toxicity of sediment pore water to D. magna, gave no indication of the presence of substances in acutely toxic concentrations to this species. It can be speculated that, despite of high metal contents, the observed toxicity was low because of the high contents of clay and iron, as well as sulphide. Also, based on a comparison with the Danube sediment and Vojvodina soil in general, the data of the Begej sediment contamination with 238U and 137Cs. The 137Cs data were used for approximate dating of the sediment. No traces of contamination by nuclear power plants in the region were found, while the presence of technologically enhanced naturally occurring radioactive materials (TENORM) was proved. Conclusions based on different criteria for sediment quality assessment were in some cases contradictory. Study also showed that radioactivity aspects can be useful in sediment quality surveys. The obtained results will be invaluable for the future activities regarding integrated water management based on EC Water Framework Directive (2000/60/EC) in the Danube basin, and particularly in the region of crossborder water body of the Begej Canal. PMID:16527352

Dalmacija, B; Prica, M; Ivancev-Tumbas, I; van der Kooij, A; Roncevic, S; Krcmar, D; Bikit, I; Teodorovic, I

2006-07-01

247

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

248

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

PubMed

The construction of an alkali-metal ion source is presented. It allows the acceleration of rubidium ions to an energy that enables the penetration through monolayers of graphene and hexagonal boron nitride. Rb atoms are sublimated from an alkali-metal dispenser. The ionization is obtained by surface ionization and desorption from a hot high work function surface. The ion current is easily controlled by the temperature of ionizer. Scanning Tunneling Microscopy measurements confirm ion implantation. PMID:24387480

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

2013-12-01

249

Equilibrium sorption isotherm for metal ions on tree fern  

Microsoft Academic Search

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

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

2002-01-01

250

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

E-print Network

describe the application of a colorimetric phospholipid/ polydiacetylene (PDA) biomimetic membrane assay a biphasic concentration-dependent interaction, with a break point around the critical micelle concentration). The molecule was designed to modify activities of metal ions such as copper, zinc, calcium, and iron in lipid

Jelinek, Raz

251

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

DOEpatents

The specification discloses a method for the extraction of metal ions having a reduction potential of above about +0.3 from an aqueous solution. The method includes contacting the aqueous solution with a polymeric extractant having primary phosphinic acid groups, secondary phosphine oxide groups, or both phosphinic acid and phosphine oxide groups.

Alexandratos, Spiro D. (Knoxville, TN)

1987-01-01

252

Superhydrogels of nanotubes capable of capturing heavy-metal ions.  

PubMed

Self-assembly regulated by hydrogen bonds was successfully achieved in the system of lithocholic acid (LCA) mixed with three organic amines, ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA), in aqueous solutions. The mixtures of DEA/LCA exhibit supergelation capability and the hydrogels consist of plenty of network nanotubes with uniform diameters of about 60 nm determined by cryogenic TEM. Interestingly, the sample with the same concentration in a system of EA and LCA is a birefringent solution, in which spherical vesicles and can be transformed into nanotubes as the amount of LCA increases. The formation of hydrogels could be driven by the delicate balance of diverse noncovalent interactions, including electrostatic interactions, hydrophobic interactions, steric effects, van der Waals forces, and mainly hydrogen bonds. The mechanism of self-assembly from spherical bilayer vesicles into nanotubes was proposed. The dried hydrogels with nanotubes were explored to exhibit the excellent capability for capturing heavy-metal ions, for example, Cu(2+), Co(2+), Ni(2+), Pb(2+), and Hg(2+). The superhydrogels of nanotubes from the self-assembly of low-molecular-weight gelators mainly regulated by hydrogen bonds used for the removal of heavy-metal ions is simple, green, and high efficiency, and provide a strategic approach to removing heavy-metal ions from industrial sewage. PMID:24136830

Song, Shasha; Wang, Haiqiao; Song, Aixin; Hao, Jingcheng

2014-01-01

253

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

PubMed

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

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

2014-01-01

254

Radioactive Ion Beam Production from the Fission of Thorium Oxide Targets  

NASA Astrophysics Data System (ADS)

Hollifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory is one of the few facilities in the world that provides radioactive ion beams (RIB), crucial for nuclear astrophysics, nuclear structure, and stewardship science. Neutron-rich beams are produced by proton-induced nuclear fission of actinide compounds such as uranium carbide or thorium oxide. The goal of this project has two folds. First, compare the beam yield produced from both a low density and a high-density ThO2 target. Second, find the relation the 40 MeV proton beam that drives the RIB production is fully stopped in the high density, ˜8 g/cm^3 ThO2, but not in the low-density 0.8 g/cm^3 ThO^2. The low-density target does not use all of the beam intensity. In this particular experiment, the production yields from 40MeV and 30MeV protons have been measured on the low-density target. The comparison of the calculated production yields of 40 MeV and 30 MeV protons shows a factor of two between these different energies. The experiment was conducted using an on-line mass separator, and specific masses of the RIB were collected onto a tape. This allows a direct comparison of the low and high density ThO2 target. Release data from the high and low-density targets will be shown and discussed.

Armagan, Hakan; Carter, H. K.; Stracener, D. W.; Spejewski, E. H.; Kronenberg, A.

2007-04-01

255

Proceedings of the workshop on the science of intense radioactive ion beams  

SciTech Connect

This report contains the proceedings of a 2-1/2 day workshop on the Science of Intense Radioactive Ion Beams which was held at the Los Alamos National Laboratory on April 10--12, 1990. The workshop was attended by 105 people, representing 30 institutions from 10 countries. The thrust of the workshop was to develop the scientific opportunities which become possible with a new generation intense Radioactive Ion Beam (RIB) facility, currently being discussed within North America. The workshop was organized around five primary topics: (1) reaction physics; (2) nuclei far from stability/nuclear structure; (3) nuclear astrophysics; (4) atomic physics, material science, and applied research; and (5) facilities. Overview talks were presented on each of these topics, followed by 1-1/2 days of intense parallel working group sessions. The final half day of the workshop was devoted to the presentation and discussion of the working group summary reports, closing remarks and a discussion of future plans for this effort.

McClelland, J.B.; Vieira, D.J. (comps.)

1990-10-01

256

Template-directed synthesis of oligoguanylic acids - Metal ion catalysis  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

257

An investigation into the mechanism of pseudospark producing metal ion beams  

NASA Astrophysics Data System (ADS)

A multiplate pseudospark chamber, whose electrodes were fabricated with different metal materials, was designed and tested as a metal ion source. The ion beam implantation combined with Rutherford backscattering (RBS) measurement was used to understand whether these ion beams come from the anode plasma or the cathode plasma. The RBS measurements have demonstrated the following results: (1) pseudospark produced metal ion beams mainly consist of ions from the cathode materials; (2) the ion beam current increases rapidly with the pseudospark discharge voltage first and then saturates; and (3) the energy of the extracted metal ions is much less than the voltage between the anode and the cathode, therefore the high discharge voltage does not correspond to the high ion energy. A possible mechanism of pseudospark producing metal ion beams is discussed.

Cai, C. G.; Zhao, W. J.; Yan, S.; Le, X. Y.; Han, B. X.; Xue, J. M.; Wang, Y. G.; Jiang, X. L.

2000-02-01

258

Surface modified, collapsible controlled pore glass materials for sequestration and immobilization of trivalent metal ions.  

SciTech Connect

We report a one-pot method for sequestration, containment, and immobilization of lanthanide (Ln) ions from dilute aqueous waste streams. The approach is based on the use of collapsible, surface modified controlled pore glass (CPG) nanomaterials. We present several approaches for a single-step chemical modification of 3-propylaminated CPGs that yield highly efficient Ln-extracting materials with distribution coefficients exceeding 10000 mL/g. The resulting Ln complexes were studied using X-ray absorption, magnetic resonance, and time-resolved luminescence spectroscopies. One of these CPG materials involving an imidodi(methanediphosphate) moiety demonstrated high extraction efficacy, significant ionic radius sensitivity, and exceptional tolerance to masking agents, which is conducive to its use for removal of traces of radionuclide ions from aqueous TALSPEAK raffinate (trivalent actinide-lanthanide separation by phosphorus reagent extraction from aqueous complexes process used in processing of spent nuclear fuel). The glass loaded with the extracted metal ions can be calcined and sintered at 1100 C, yielding fused material that buries Ln ions in the vitreous matrix. This processing temperature is significantly lower than 1700 C that is required for direct vitrification of lanthanide oxides in high-silica glass. X-ray absorption spectroscopy and acid leaching tests indicate that the immobilized ions are isolated and dispersed in the fused glass matrix. Thus, the method integrates Ln ions into the glass network. The resulting glass can be used for temporary storage or as the source of silica for production of borosilicate waste forms that are used for long-term disposal of high level radioactive waste.

Shkrob, I.; Tisch, A.; Marin, T.; Muntean, J.; Kaminski, M.; Kropf, A. (Chemical Sciences and Engineering Division); (Benedictine Univ.)

2011-04-20

259

The Radioactive Ion Beams in Brazil (RIBRAS) facility. Description, program, main results, future plans  

NASA Astrophysics Data System (ADS)

RIBRAS (Radioactive Ion Beams in Brazil) is a facility installed at the Institute of Physics of the University of São Paulo (IFUSP), Brazil. The RIBRAS system consists of two superconducting solenoids and uses the "in-flight method" to produce radioactive ion beams using the primary beam provided by the 8UD Pelletron Tandem of IFUSP. The ion beams produced so far by RIBRAS are 6He, 8Li, 7Be, 10Be, 8B, 12B with intensities that can vary from 104 to 106 pps. Initially the experimental program covered the study of elastic and inelastic scattering with the objective to study the interaction potential and the reaction mechanisms between weakly bound (RIB) and halo (6He and 8B projectiles on light, medium and heavy mass targets. With highly purified beams, the study of resonant elastic scattering and resonant transfer reactions, using inverse kinematics and thick targets, has also been included in our experimental program. Also, transfer reactions of astrophysical interest and fusion reactions induced by halo nuclei are part of the near-future research program. Our recent results on elastic scattering, alpha-particle production and total reaction cross sections, as well as the resonant elastic and transfer reactions, are presented. Our plans for the near future are related to the installation of a new beam line and a cave for gamma-ray detection. We intend to place in operation a large area neutron detector available in our laboratory. The long-range plans could be the move of the RIBRAS system to the more energetic beam line of the LINAC post-accelerator (10MeV/nucleon primary beams) still in construction in our laboratory.

Lépine-Szily, A.; Lichtenthäler, R.; Guimarães, V.

2014-08-01

260

Radiation damage from single heavy ion impacts on metal surfaces  

SciTech Connect

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

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

1998-06-01

261

Luminescent monitoring of metal dititanium triphosphates as promising materials for radioactive waste confinement  

NASA Astrophysics Data System (ADS)

The potential use of luminescent probes for control over the structural state of MTi 2(PO 4) 3 double metal phosphates as host materials for radioactive waste confinement is examined. Luminescence spectra of pure and metal (Al, In, V) and rare-earth (Pr, Sm, Dy) doped MTi 2(PO 4) 3 (M = Li, Na, K) phosphate compounds (in crystalline and related amorphous forms) under X-ray, VUV (synchrotron radiation), UV and visible light excitations are analyzed. Electronic structure and absorption spectra of NaTi 2(PO 4) 3 crystals are calculated by the full-potential LAPW method. The origin of the self and impurity emission bands of MTi 2(PO 4) 3 materials is defined. It was shown that nitrogen laser with 337.1 nm generation wavelength is the most effective excitation source for remote monitoring of incorporation of various types of waste elements into MTi 2(PO 4) 3 hosts and for control over states of these hosts during storage of radioactive waste.

Nedilko, S.; Hizhnyi, Yu.; Chukova, O.; Nagornyi, P.; Bojko, R.; Boyko, V.

2009-03-01

262

Removal of radioactive materials and heavy metals from water using magnetic resin  

DOEpatents

Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately. 9 figs.

Kochen, R.L.; Navratil, J.D.

1997-01-21

263

Removal of radioactive materials and heavy metals from water using magnetic resin  

DOEpatents

Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately.

Kochen, Robert L. (Boulder, CO); Navratil, James D. (Simi Valley, CA)

1997-01-21

264

Analysis of the application of decontamination technologies to radioactive metal waste minimization using expert systems  

SciTech Connect

Radioactive metal waste makes up a significant portion of the waste currently being sent for disposal. Recovery of this metal as a valuable resource is possible through the use of decontamination technologies. Through the development and use of expert systems a comparison can be made of laser decontamination, a technology currently under development at Ames Laboratory, with currently available decontamination technologies for applicability to the types of metal waste being generated and the effectiveness of these versus simply disposing of the waste. These technologies can be technically and economically evaluated by the use of expert systems techniques to provide a waste management decision making tool that generates, given an identified metal waste, waste management recommendations. The user enters waste characteristic information as input and the system then recommends decontamination technologies, determines residual contamination levels and possible waste management strategies, carries out a cost analysis and then ranks, according to cost, the possibilities for management of the waste. The expert system was developed using information from literature and personnel experienced in the use of decontamination technologies and requires validation by human experts and assignment of confidence factors to the knowledge represented within.

Bayrakal, S.

1993-09-30

265

Aligned nanogold assisted one step sensing and removal of heavy metal ions.  

PubMed

We depict a novel strategy exploiting the chemistry of metal ion adsorption for detection and sequestration of toxic heavy metal from processed water using gold nanoparticles capped with 4-aminothiophenol. The interaction between 4-aminothiophenol capped gold nanoparticles and heavy metal ions was studied as a function of time and concentration using TEM, HRTEM, SEM, EDS, and I-V characterization. Experiments confirmed that pH is one of the crucial controlling parameters. Adsorption capacity was monitored using AAS, UV-vis spectroscopy and I-V measurement. In the absence of any alloy formation between Au and heavy metal ions, the desorption of the heavy metal ions from 4-aminothiophenol capped gold nanoparticles surface by pH modulation serves as a mean of collection of heavy metal ions. Experiments revealed that the concentration of heavy metal ions in processed water after adsorption is below the maximum permissible limit set by the WHO. PMID:21851947

Chauhan, Neha; Gupta, Shweta; Singh, Nahar; Singh, Sukhvir; Islam, Saikh S; Sood, Kedar N; Pasricha, Renu

2011-11-01

266

Hydrolysis of Naptalam and Structurally Related Amides: Inhibition by Dissolved Metal Ions and Metal (Hydr)Oxide Surfaces  

E-print Network

Hydrolysis of Naptalam and Structurally Related Amides: Inhibition by Dissolved Metal Ions hydrolysis between pH 3.6 and pH 6.5. Metal ion-naptalam complex formation is important since additionOOH inhibit naptalam hydrolysis to a lesser degree; inhibition is proportional to the extent of naptalam

Huang, Ching-Hua

267

Rotating target facility for in-flight radioactive ion beam production using a recoil mass spectrometer  

NASA Astrophysics Data System (ADS)

A facility has been developed for production of light radioactive ion beams (RIBs) using (p,n), (d,n) reactions in inverse kinematics using an in-flight technique. Primary beams from the 15UD Pelletron accelerator are used on a hydrogenous target and the RIB is separated and re-focused to a secondary target position using the existing recoil mass spectrometer (RMS), HIRA operated in a new ion-optical configuration. To satisfy the ion-optical requirement of a well-defined object spot-size, we opted for polypropylene foil targets instead of hydrogen gas. As these foils get rapidly damaged with beam irradiation, a new design has been used to fabricate a rotary/linear motion device. This design allows the utilization of large area foils as production targets. It also, intrinsically, avoids scattering of primary beam from unwanted materials, which is crucial for beam rejection with an RMS operating at zero degrees. In this paper we present the details of the design and beam test results.

Varughese, T.; Das, J. J.; Madhavan, N.; Sugathan, P.; Madhusudhana Rao, P. V.; Jhingan, A.; Nath, S.; Sinha, A. K.; Zacharias, J.

2004-03-01

268

Altering the Divalent Metal Ion Preference of RNase E.  

PubMed

RNase E is a major intracellular endoribonuclease in many bacteria and participates in most aspects of RNA processing and degradation. RNase E requires a divalent metal ion for its activity. We show that only Mg(2+) and Mn(2+) will support significant rates of activity in vitro against natural RNAs, with Mn(2+) being preferred. Both Mg(2+) and Mn(2+) also support cleavage of an oligonucleotide substrate with similar kinetic parameters for both ions. Salts of Ni(2+) and Zn(2+) permitted low levels of activity, while Ca(2+), Co(3+), Cu(2+), and Fe(2+) did not. A mutation to one of the residues known to chelate Mg(2+), D346C, led to almost complete loss of activity dependent on Mg(2+); however, the activity of the mutant enzyme was fully restored by the presence of Mn(2+) with kinetic parameters fully equivalent to those of wild-type enzyme. A similar mutation to the other chelating residue, D303C, resulted in nearly full loss of activity regardless of metal ion. The properties of RNase E D346C enabled a test of the ionic requirements of RNase E in vivo. Plasmid shuffling experiments showed that both rneD303C (i.e., the rne gene encoding a D-to-C change at position 303) and rneD346C were inviable whether or not the selection medium was supplied with MnSO4, implying that RNase E relies on Mg(2+) exclusively in vivo. PMID:25404697

Thompson, Katharine J; Zong, Jeff; Mackie, George A

2015-02-01

269

New Catalytic DNA Biosensors for Radionuclides and Metal ions  

SciTech Connect

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

Lu, Yi

2003-06-01

270

New Catalytic DNA Biosensors for Radionuclides and Metal ions  

SciTech Connect

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

Lu, Yi

2002-06-01

271

ION IMPLANTATION AND HYPERFINE INTERACTIONS IN METALS Institut de Physique Nuclaire, BP 1, 91406 Orsay, France  

E-print Network

575 ION IMPLANTATION AND HYPERFINE INTERACTIONS IN METALS H. BERNAS Institut de Physique Nucléaire is given, with a view to presenting their applications in ion-implantation studies of metals. Some typical in hyperfine interaction studies after ion-implantation. REVUE DE PHYSIQUE APPLIQU�E TOME 9, MAI 1974, PAGE

Boyer, Edmond

272

The kinetics of sorption of divalent metal ions onto sphagnum moss peat  

Microsoft Academic Search

A pseudo-second order rate equation describing the kinetics of sorption of divalent metal ions onto sphagnum moss peat at different initial metal ion concentrations and peat doses has been developed. The kinetics of sorption were followed based on the amounts of metal sorbed at various time intervals. Results show that sorption (chemical bonding) might be rate-limiting in the sorption of

Y. S. Ho; G. McKay

2000-01-01

273

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

SciTech Connect

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

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

1999-06-13

274

Sensitive metal ions (II) determination with resonance Raman method  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

275

Printed disposable colorimetric array for metal ion discrimination.  

PubMed

One of the main limiting factors in optical sensing arrays is the reproducibility in the preparation, typically by spin coating and drop casting techniques, which produce membranes that are not fully homogeneous. In this paper, we increase the discriminatory power of colorimetric arrays by increasing the reproducibility in the preparation by inkjet printing and measuring the color from the image of the array acquired by a digital camera, using the H coordinate of the HSV color space as the analytical parameter, which produces robust and precise measurements. A disposable 31 mm × 19 mm nylon membrane with 35 sensing areas with 7 commercial chromogenic reagents makes it possible to identify 13 metal ions and to determine mixtures with up to 5 ions using a two-stage neural network approach with higher accuracy than with previous approaches. PMID:25088790

Ariza-Avidad, M; Salinas-Castillo, A; Cuéllar, M P; Agudo-Acemel, M; Pegalajar, M C; Capitán-Vallvey, L F

2014-09-01

276

Sodium niobate adsorbents doped with tantalum (TaV) for the removal of bivalent radioactive ions in waste waters.  

PubMed

Sodium niobates doped with different amounts of tantalum (Ta(V)) were prepared via a thermal reaction process. It was found that pure nanofibrils and bar like solids can be obtained when tantalum is introduced into the reaction system. For the well crystallized fibril solids, the Na(+) ions are difficult to exchange, and the radioactive ions such as Sr(2+) and Ra(2+) just deposit on the surface of the fibers during the sorption process, resulting in lower sorption capacity and distribution coefficients (K(d)). However, the bar like solids are poorly crystallized and have many exchangeable Na(+) ions. They are able to remove highly hazardous bivalent radioactive isotopes such as Sr(2+) and Ra(2+) ions. Even in the presence of many Na(+) ions, they also have higher K(d). More importantly, such sorption finally intelligently triggers considerable collapse of the structure, resulting in permanent entrapment of the toxic bivalent cations in the solids, so that they can be safely disposed of. This study highlights new opportunities for the preparation of Nb-based adsorbents to efficiently remove toxic radioactive ions from contaminated water. PMID:21266294

Paul, Blain; Yang, Dongjiang; Martens, Wayde N; Frost, Ray L

2011-04-01

277

Electrolyte materials containing highly dissociated metal ion salts  

DOEpatents

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

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

1996-07-23

278

Electrolyte materials containing highly dissociated metal ion salts  

DOEpatents

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

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

1996-07-23

279

Novel fungus-titanate bio-nanocomposites as high performance adsorbents for the efficient removal of radioactive ions from wastewater.  

PubMed

Reclaimable adsorbents have a critical application in the adsorption of radioactive materials. In this study, the novel bio-nanocomposites comprising fungi and titanate nanotubes are successfully synthesized by a simple and low-cost method. Morphological characterizations and composite mechanism analysis confirm that the composites are sufficiently stable to avoid dust pollution resulting from the titanate nanomaterials. Adsorption experiments demonstrate that the bio-nanocomposites are efficient adsorbents with a saturated sorption capacity as high as 120 mg g(-1) (1.75 meq. g(-1)) for Ba(2+) ions. The results suggest that the bio-nanocomposites can be used as promising radioactive adsorbents for removing radioactive ions from water caused by nuclear leakage. PMID:24287628

Xu, Mingze; Wei, Guodong; Liu, Na; Zhou, Liang; Fu, Chengwei; Chubik, M; Gromov, A; Han, Wei

2014-01-21

280

Radiation and Electromagnetic Induction Data Fusion for Detection of Buried Radioactive Metal Waste - 12282  

SciTech Connect

At the United States Army's test sites, fired penetrators made of Depleted Uranium (DU) have been buried under ground and become hazardous waste. Previously, we developed techniques for detecting buried radioactive targets. We also developed approaches for locating buried paramagnetic metal objects by utilizing the electromagnetic induction (EMI) sensor data. In this paper, we apply data fusion techniques to combine results from both the radiation detection and the EMI detection, so that we can further distinguish among DU penetrators, DU oxide, and non- DU metal debris. We develop a two-step fusion approach for the task, and test it with survey data collected on simulation targets. In this work, we explored radiation and EMI data fusion for detecting DU, oxides, and non-DU metals. We developed a two-step fusion approach based on majority voting and a set of decision rules. With this approach, we fuse results from radiation detection based on the RX algorithm and EMI detection based on a 3-step analysis. Our fusion approach has been tested successfully with data collected on simulation targets. In the future, we will need to further verify the effectiveness of this fusion approach with field data. (authors)

Long, Zhiling; Wei, Wei; Turlapaty, Anish; Du, Qian; Younan, Nicolas H. [Department of Electrical and Computer Engineering (United States); Waggoner, Charles [Institute for Clean Energy Technology, Mississippi State University, MS 39762 (United States)

2012-07-01

281

Synthesis and characterization of novel nitrogen-containing ligands for metal ion separations  

NASA Astrophysics Data System (ADS)

A serious limiting factor in the continued development of nuclear power is the disposal of high-level radioactive waste from spent nuclear fuel. The PUREX process can be used for the recovery of U and Pu, but it does not separate the products of fission which are potentially useful, but currently cause most of our problems with radioactive waste. An important complicating factor is the presence of large amounts of lanthanides in dissolved spent nuclear fuel. The separation of lanthanides (Ln) from actinides (An) is therefore critical to the future of nuclear power. One approach to recovering these materials and decreasing the volume of the radioactive waste is the development of novel, highly selective organic ligands for the lanthanide and actinide ions. The focus of this dissertation is to design and synthesize new tridentate polyaza-ligands expected to exhibit affinity for first-row transition metals, lanthanides and actinides. In general, these chelating agents are structurally and functionally related to the pyridine and bipyridine bis-triazinyl compounds that have been investigated for potential application as separations agents for radioactive materials. Selected 1,2,3-triazoles have been synthesized using Sharpless' "Click Chemistry". Variation of the backbone and substituents on the triazole ring allows for facile modification of the cation binding pocket and phase compatibility properties of the new compounds. Characterization of the new ligands was performed using conventional analytical methods. Overall, the studies with three different ligands revealed useful information about the continuing effort of ligand design for actinide (III)/lanthanide (III) separations. Crystal structures established the purity of the organic molecules by showing that the PTMP and BDTP ligands are able to bind transition metals. Also, it was shown that the BDTB ligand was able to bind to Nd 3+ as observed from the spectrophotometric titrations and the calculated binding constant. To increase the lipophilicity of the ligand, the addition of an alkyl chain on the 4-position of the pyridine ring could be made. This confirms that scientists are advancing in the area of ligand design and hopefully one day the ligand with all of the desired characteristics will be used to close the nuclear fuel cycle.

Hoch, Cortney Leigh

282

Nuclear reactions with 11C and 14O radioactive ion beams  

SciTech Connect

Radioactive ion beams (RIBs) have been shown to be a useful tool for studying proton-rich nuclides near and beyond the proton dripline and for evaluating nuclear models. To take full advantage of RIBs, Elastic Resonance Scattering in Inverse Kinematics with Thick Targets (ERSIKTT), has proven to be a reliable experimental tool for investigations of proton unbound nuclei. Following several years of effort, Berkeley Experiments with Accelerated Radioactive Species (BEARS), a RIBs capability, has been developed at the Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. The current BEARS provides two RIBs: a 11C beam of up to 2x108 pps intensity on target and an 14O beam of up to 3x104 pps intensity. While the development of the 11C beam has been relatively easy, a number of challenges had to be overcome to obtain the 14O beam. The excellent 11C beam has been used to investigate several reactions. The first was the 197Au(11C,xn)208-xnAt reaction, which was used to measure excitation functions for the 4n to 8n exit channels. The measured cross sections were generally predicted quite well using the fusion-evaporation code HIVAP. Possible errors in the branching ratios of ?? decays from At isotopes as well as the presence of incomplete fusion reactions probably contribute to specific overpredictions. 15F has been investigated by the p(14O,p)14O reaction with the ERSIKTT technology. Several 14O+p runs have been performed. Excellent energy calibration was obtained using resonances from the p(14N,p)14N reaction in inverse kinematics, and comparing the results to those obtained earlier with normal kinematics. The differences between 14N+p and 14O+p in the stopping power function have been evaluated for better energy calibration. After careful calibration, the energy levels of 15F were fitted with an R-matrix calculation. Spins and parities were assigned to the two observed resonances. This new measurement of the 15F ground state supports the disappearance of the Z = 8 proton magic number for odd Z, Tz=-3/2 nuclei. It is expected that future work on proton-rich nuclides will rely heavily on RIBs and/or mass separators. Currently, radioactive ion beam intensities are sufficient for the study of a reasonable number of very proton-rich nuclides.

Guo, Fanqing

2004-12-09

283

The binding of cupric ions to bovine pancreatic ribonuclease studied with diligand metal-ion buffers  

PubMed Central

A procedure has been developed for the use of metal-ion buffers that depends on the formation of 2:1 complexes between suitable chelators and metal ions. ?-Alanine has been used as the chelator for Cu2+ ions in a study of Cu2+ binding by bovine pancreatic ribonuclease by the equilibrium-dialysis technique at pH7·0, 6·1 and 5·2. The results indicated the presence of two avid binding sites, the more avid group being implicated in the inhibition of enzyme activity by Cu2+ ions. The binding constants of the more avid site were 2·97×107, 7·97×105 and 1·25×104 at pH7·0, 6·1 and 5·2 respectively, and the binding constants of the less avid site were 5·27×106 and 1·71×105 at pH7·0 and 6·1 respectively. The data show that the Cu2+ is chelated to the protein through at least two ligand groups on the ribonuclease molecule. PMID:6070125

Saundry, R. H.; Stein, W. D.

1967-01-01

284

Rare Earth Metal Silicides Synthesized by High Current Metal Ion Implantation  

SciTech Connect

The YSi2, LaSi2, CeSi2, PrSi2, NdSi2, SmSi2, GdSi2, TbSi2, DySi2, and ErSi2 layers were formed on Si wafers by respective high current metal-ion implantation using a metal vacuum vapor arc (MEVVA) ion source and the formation temperature was considerable lower than the critical temperatures (300-350 deg. C) required for the rare earth metal silicides by solid-state reaction. It was found that the crystalline structures could be improved with increasing slightly the formation temperature as well as the implantation dose. Concerning the growth kinetics, in some cases, fractal patterns were observed on Si surfaces and the branches of the fractals consisted of the grains of respective precipitated silicides. Interestingly, the fractal dimension increased with formation temperature and eventually approached to a value of 2.0, corresponding to a continuous layer, which was required in practical application. The formation mechanism as well as the growth kinetics was discussed in terms of the far-from-equilibrium process involved in the MEVVA ion implantation.

Cheng, X.Q.; Wang, R.S.; Tang, X.J.; Liu, B.X. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2003-08-26

285

Selective exchange of divalent transition metal ions in cryptomelane-type manganic acid with tunnel structure  

SciTech Connect

The ion-exchange selectivity of divalent transition metal ions on cryptomelane-type manganic acid (CMA) with tunnel structure has been studied using the distribution coefficients ([ital K][sub [ital d

Tsuji, M. (Department of Chemistry, Faculty of Science, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152 (Japan)); Komarneni, S. (Materials Research Laboratory and Department of Agronomy, The Pennsylvania State University, University Park, Pennsylvania 16802-4801 (United States))

1993-03-01

286

Metal complexes containing natural and and artificial radioactive elements and their applications.  

PubMed

Recent advances (during the 2007-2014 period) in the coordination and organometallic chemistry of compounds containing natural and artificially prepared radionuclides (actinides and technetium), are reviewed. Radioactive isotopes of naturally stable elements are not included for discussion in this work. Actinide and technetium complexes with O-, N-, N,O, N,S-, P-containing ligands, as well ?-organometallics are discussed from the view point of their synthesis, properties, and main applications. On the basis of their properties, several mono-, bi-, tri-, tetra- or polydentate ligands have been designed for specific recognition of some particular radionuclides, and can be used in the processes of nuclear waste remediation, i.e., recycling of nuclear fuel and the separation of actinides and fission products from waste solutions or for analytical determination of actinides in solutions; actinide metal complexes are also usefulas catalysts forcoupling gaseous carbon monoxide,as well as antimicrobial and anti-fungi agents due to their biological activity. Radioactive labeling based on the short-lived metastable nuclide technetium-99m ((99m)Tc) for biomedical use as heart, lung, kidney, bone, brain, liver or cancer imaging agents is also discussed. Finally, the promising applications of technetium labeling of nanomaterials, with potential applications as drug transport and delivery vehicles, radiotherapeutic agents or radiotracers for monitoring metabolic pathways, are also described. PMID:25061724

Kharissova, Oxana V; Méndez-Rojas, Miguel A; Kharisov, Boris I; Méndez, Ubaldo Ortiz; Martínez, Perla Elizondo

2014-01-01

287

Accurate quantification of radioactive materials by x-ray fluorescence : gallium in plutonium metal /.  

SciTech Connect

Two XRF specimen preparation methods were investigated for quantifying gallium in plutonium metal. Gallium in plutonium was chosen here as an example for demonstrating the efficacy of wavelength dispersive XRF for quantifying radioactive materials. The steps necessary to handle such materials safely will also be discussed. Quantification of plutonium samples by a well-established aqueous specimen preparation method resulted in relative precision and accuracy values of well less than 1%. As an alternative to the aqueous approach, a dried residue method was studied. Quantification of gallium in samples using this method resulted in relative precision and accuracy values an order of magnitude worse, but the method is faster, safer, and generates less waste than the aqueous process. The specimen preparation details and analysis results using each method will be presented here.

Worley, C. G. (Christopher G.)

2002-01-01

288

Viscoplasticity of simulated high-level radioactive waste glass containing platinum group metal particles  

NASA Astrophysics Data System (ADS)

The shear rate dependency of the viscosity of three simulated high-level radioactive waste glasses containing 0, 1.2 and 4.5 wt% platinum group metals (PGMs) was examined at a temperature range of 1173-1473 K by a rotating viscometer. Shear stress when the shear rate equals zero, i.e. yield stress, was also measured by capillary method. The viscosity of the glass containing no PGM was shear rate-independent Newtonian fluid. On the other hand, the apparent viscosity of the glasses containing PGMs increased with decreasing shear rate, and nonzero amount of yield stresses were detected from both glasses. The viscosity and yield stress of the glass containing 4.5 wt% PGMs was roughly one to two orders of magnitude greater than the glass containing 1.2 wt% PGMs. These viscoplastic properties were numerically expressed by Casson equation.

Uruga, Kazuyoshi; Usami, Tsuyoshi; Tsukada, Takeshi; Komamine, Satoshi; Ochi, Eiji

2014-09-01

289

Fernald`s dilemma: Do we recycle the radioactively contaminated metals, or do we bury them?  

SciTech Connect

During the past five years, a number of U.S. Department of Energy (DOE) funded efforts have demonstrated the technical efficacy of converting various forms of radioactive scrap metal (RSM) into useable products. From the development of large accelerator shielding blocks, to the construction of low level waste containers, technology has been applied to this fabrication process in a safe and stakeholder supported manner. The potential health and safety risks to both workers and the public have been addressed. The question remains; can products be fabricated from RSM in a cost efficient and market competitive manner? This paper presents a methodology for use within DOE to evaluate the costs and benefits of recycling and reusing some RSM, rather than disposing of this RSM in an approved burial site. This life cycle decision methodology, developed by both the Oak Ridge National Laboratory (ORNL) and DOE Fernald is the focus of the following analysis.

Yuracko, K.L.; Hadley, S.W.; Perlack, R.D. [and others

1996-06-01

290

Dissecting the Metal Selectivity of MerR Monovalent Metal Ion Sensors in Salmonella  

PubMed Central

Two homologous transcription factors, CueR and GolS, that belong to the MerR metalloregulatory family are responsible for Salmonella Cu and Au sensing and resistance, respectively. They share similarities not only in their sequences, but also in their target transcription binding sites. While CueR responds similarly to Au, Ag, or Cu to induce the expression of its target genes, GolS shows higher activation by Au than by Ag or Cu. We showed that the ability of GolS to distinguish Au from Cu resides in the metal-binding loop motif. Here, we identify the amino acids within the motif that determine in vivo metal selectivity. We show that residues at positions 113 and 118 within the metal-binding loop are the main contributors to metal selectivity. The presence of a Pro residue at position 113 favors the detection of Cu, while the presence of Pro at position 118 disfavors it. Our results highlight the molecular bases that allow these regulators to coordinate the correct metal ion directing the response to a particular metal injury. PMID:23645605

Ibáñez, María M.; Cerminati, Sebastián; Checa, Susana K.

2013-01-01

291

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

E-print Network

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

Meng, Shirley Y.

292

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

PubMed

The exposure of aqueous nanoelectrospray droplets to various organic vapors can dramatically reduce sodium adduction on protein ions in positive ion mass spectra. Volatile alcohols, such as methanol, ethanol, and isopropanol lead to a significant reduction in sodium ion adduction but are not as effective as acetonitrile, acetone, and ethyl acetate. Organic vapor exposure in the negative ion mode, on the other hand, has essentially no effect on alkali ion adduction. Evidence is presented to suggest that the mechanism by which organic vapor exposure reduces alkali ion adduction in the positive mode involves the depletion of alkali metal ions via ion evaporation of metal ions solvated with organic molecules. The early generation of metal/organic cluster ions during the droplet desolvation process results in fewer metal ions available to condense on the protein ions formed via the charged residue mechanism. These effects are demonstrated with holomyoglobin ions to illustrate that the metal ion reduction takes place without detectable protein denaturation, which might be revealed by heme loss or an increase in charge state distribution. No evidence is observed for denaturation with exposure to any of the organic vapors evaluated in this work. PMID:25517019

DeMuth, J Corinne; McLuckey, Scott A

2015-01-20

293

Chemical and thermal stability of isotypic metal-organic frameworks: effect of metal ions.  

PubMed

Chemical and thermal stabilities of isotypic metal-organic frameworks (MOFs) like Al-BDC (Al-benzenedicarboxylate called MIL-53-Al), Cr-BDC (MIL-53-Cr) and V-BDC (MIL-47-V), after purification to remove uncoordinated organic linkers, have been compared to understand the effect of the central metal ions on the stabilities of the porous MOF-type materials. Chemical stability to acids, bases, and water decreases in the order of Cr-BDC>Al-BDC>V-BDC, suggesting stability increases with increasing inertness of the central metal ions. However, thermal stability decreases in the order of Al-BDC>Cr-BDC> V-BDC, and this tendency may be explained by the strength of the metal-oxygen bond in common oxides like Al(2)O(3), Cr(2)O(3), and V(2)O(5). In order to evaluate precisely the stability of a MOF, it is necessary to remove uncoordinated organic linkers that are located in the pores of the MOF, because a filled MOF may be more stable than the same MOF after purification. PMID:21547968

Kang, In Joong; Khan, Nazmul Abedin; Haque, Enamul; Jhung, Sung Hwa

2011-05-27

294

Mapping metal ions at the catalytic centres of two intron-encoded endonucleases  

Microsoft Academic Search

Divalent metal ions play a crucial role in forming the catalytic centres of DNA endonucleases. Substitution of Mg2+ ions by Fe2+ ions in two archaeal intron-encoded homing endonucleases, I-DmoI and I-PorI, yielded functional enzymes and enabled the generation of reactive hydroxyl radicals within the metal ion binding sites. Specific hydroxyl radical-induced cleavage was observed within, and immediately after, two conserved

Jens Lykke-Andersen; Roger A. Garrett; Jørgen Kjems

1997-01-01

295

Metal ion sorption by untreated and chemically treated biomass  

SciTech Connect

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

Kilbane, J.J.; Xie, J.

1992-12-31

296

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

297

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

SciTech Connect

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

Aymar, M.; Dulieu, O. [Laboratoire Aime Cotton, CNRS, UPR3321, Ba circumflex t. 505, Univ Paris-Sud, 91405 Orsay Cedex (France); Guerout, R. [Laboratoire Kastler-Brossel, CNRS, ENS, Univ Pierre et Marie Curie case 74, Campus Jussieu, F-75252 Paris Cedex 05 (France)

2011-08-14

298

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

E-print Network

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

Aymar, Mireille; Dulieu, Olivier

2011-01-01

299

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

E-print Network

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

Mireille Aymar; Romain Guérout; Olivier Dulieu

2011-02-24

300

Conditions of accumulation of radioactive metals in the process of differentiation of ultrabasic alkaline-carbonatite rock associations  

NASA Astrophysics Data System (ADS)

The distribution of radioactive elements in alkaline rocks from Polar Siberia and Ukraine shows that U and Th are markedly concentrated in carbonatite complex and nepheline syenite as final products of magma fractionation. Peralkaline nepheline syenites from Polar Siberia are characterized by very high contents of radioactive elements, which are close to the economic level. Radioactive elements are also concentrated in rocks of the carbonatite complex. For example, some soevites contain up to 294 × 10-4%U and 916 × 10-4% Th. In late dolomite carbonatites, the contents of radioactive elements are appreciably lower. The Th/U ratio in alkaline rocks of Polar Siberia is close to the chondrite value in primary high-Mg rocks and increases in late derivatives: phoscorite, calcite and dolomite carbonatites. The main amount of radioactive elements is contained in rare-metal accessory minerals: perovskite, pyrochlore, calzirtite, and apatite. Rock-forming minerals are distinguished by very low concentrations of radioactive elements. In alkaline series of the Chernigovka massif (Ukraine), U and Th also accumulate in the course of crystal fractionation, especially in phoscorites from the carbonatite complex. Mantle xenoliths and alkaline rocks from Ukraine reveal uranium specialization. Most likely, the discrepancy in fractionation of radioactive elements between Polar Siberia and Ukraine is caused by different geodynamic regimes of these provinces. The Mesozoic alkaline magmatism of Polar Siberia is a part of the Siberian superplume, whereas the Proterozoic alkaline complex in Ukraine is related to subduction of the oceanic crust.

Kogarko, L. N.

2014-07-01

301

Development of a radioactive ion beam facility using 15 UD tandem accelerator at NSC  

NASA Astrophysics Data System (ADS)

An inflight radioactive ion beam (RIB) facility is being developed at the Nuclear Science Centre (NSC), using the existing 15 UD Pelletron accelerator and the recoil mass spectrometer (RMS) HIRA. Though the basic principle of operation of the facility will be similar to those described in [1-3], ion optics of the facility are optimized for precise nuclear reaction measurements. In this facility, primary beams from the Pelletron accelerator will be used to produce RIB species using reactions such as 0954-3899/24/8/009/img10, 0954-3899/24/8/009/img11, 0954-3899/24/8/009/img12 etc in inverse kinematics. To ensure an efficient beam rejection for inverse kinematic reactions with good focusing of the RIB, HIRA will operate in a new ion optical mode. In this mode, there is an intermediate focal plane where a beam filtering slit system will be installed to stop primary beam particles while allowing RIB particles to be transported unhindered to the final focal plane which will be the secondary target position. In the case of many RIB species, more than one charge state will be focused into a single spot at the experimental target site. The design and installation of hardware for the facility is in progress. RIB species such 0954-3899/24/8/009/img13, 0954-3899/24/8/009/img14, 0954-3899/24/8/009/img15 etc, will be available with intensity in the range of 0954-3899/24/8/009/img16-0954-3899/24/8/009/img17 with 0954-3899/24/8/009/img18 diameter spot size with high purity. The facility is expected to be operational for user experiments by the end of 1998.

Das, J. J.; Sugathan, P.; Madhavan, N.; Kumar, B.; Varughese, T.; Madhusudhana Rao, P. V.; Sinha, A. K.

1998-08-01

302

Prostate cancer outcome and tissue levels of metal ions  

USGS Publications Warehouse

BACKGROUND There are several studies examining prostate cancer and exposure to cadmium, iron, selenium, and zinc. Less data are available on the possible influence of these metal ions on prostate cancer outcome. This study measured levels of these ions in prostatectomy samples in order to examine possible associations between metal concentrations and disease outcome. METHODS We obtained formalin fixed paraffin embedded tissue blocks of prostatectomy samples of 40 patients with PSA recurrence, matched 1:1 (for year of surgery, race, age, Gleason grading, and pathology TNM classification) with tissue blocks from 40 patients without recurrence (n = 80). Case-control pairs were compared for the levels of metals in areas adjacent to tumors. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for quantification of Cd, Fe, Zn, and Se. RESULTS Patients with biochemical (PSA) recurrence of disease had 12% lower median iron (95 ??g/g vs. 111 ??g/g; P = 0.04) and 21% lower zinc (279 ??g/g vs. 346 ??g/g; P = 0.04) concentrations in the normal-appearing tissue immediately adjacent to cancer areas. Differences in cadmium (0.489 ??g/g vs. 0.439 ??g/g; 4% higher) and selenium (1.68 ??g/g vs. 1.58 ??g/g; 5% higher) levels were not statistically significant in recurrence cases, when compared to non-recurrences (P = 0.40 and 0.21, respectively). CONCLUSIONS There is an association between low zinc and low iron prostate tissue levels and biochemical recurrence in prostate cancer. Whether these novel findings are a cause or effect of more aggressive tumors, or whether low zinc and iron prostatic levels raise implications for therapy, remains to be investigated. Copyright ?? 2011 Wiley-Liss, Inc.

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

2011-01-01

303

Nanoparticles reduce nickel allergy by capturing metal ions  

NASA Astrophysics Data System (ADS)

Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation.

Vemula, Praveen Kumar; Anderson, R. Rox; Karp, Jeffrey M.

2011-05-01

304

Hydrated alkali metal ions: spectroscopic evidence for clathrates.  

PubMed

The origin of enhanced abundances for some hydrated alkali metal ions, M(+)(H2O)n, where M = Cs, Rb, K, Na, and Li with between 17 and 21 water molecules attached was investigated with infrared photodissociation (IRPD) spectroscopy and by blackbody infrared radiative dissociation (BIRD) at 133 K. The abundances of clusters of Cs(+), Rb(+), and K(+) with 18 and 20 water molecules are anomalously high compared to the corresponding clusters of Na(+), and Li(+) with 20 water molecules has only a slightly enhanced abundance. BIRD results indicate that the anomalous abundance at n = 20 for the larger ions is due to the high stability of this cluster, and the significant instability of the next largest cluster, consistent with a stable core structure with 20 water molecules. IRPD spectra in the free-OH region (?3600-3800 cm(-1)) for Cs(+), Rb(+), and K(+) with 18 and 20 water molecules indicates that water molecules with a free-OH stretch accept two hydrogen bonds and donate one hydrogen bond (acceptor-acceptor-donor water) to other water molecules. No acceptor-donor (AD) bands are observed, consistent with clathrate structures for these ions. In contrast, the AD band is significant for Na(+), indicating that these clusters adopt different structures. Results for Li(+) indicate a contribution from clathrate structures at n = 20, but not at other cluster sizes. This analysis is supported by the relative intensities of bands in the hydrogen-bonding region for n = 20. PMID:23808387

Cooper, Richard J; Chang, Terrence M; Williams, Evan R

2013-08-01

305

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

PubMed

The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu(2+) ions in CuCl2·2H2O, LiCuVO4, CuCl2, and CuBr2 on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu(2+) ions of Bi2CuO4 and Li2CuO2. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling. PMID:25273418

Liu, Jia; Koo, Hyun-Joo; Xiang, Hongjun; Kremer, Reinhard K; Whangbo, Myung-Hwan

2014-09-28

306

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

NASA Astrophysics Data System (ADS)

The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu2+ ions in CuCl2.2H2O, LiCuVO4, CuCl2, and CuBr2 on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu2+ ions of Bi2CuO4 and Li2CuO2. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

Liu, Jia; Koo, Hyun-Joo; Xiang, Hongjun; Kremer, Reinhard K.; Whangbo, Myung-Hwan

2014-09-01

307

Peroxide Stress Elicits Adaptive Changes in Bacterial Metal Ion Homeostasis  

PubMed Central

Abstract Exposure to hydrogen peroxide (H2O2) and other reactive oxygen species is a universal feature of life in an aerobic environment. Bacteria express enzymes to detoxify H2O2 and to repair the resulting damage, and their synthesis is typically regulated by redox-sensing transcription factors. The best characterized bacterial peroxide-sensors are Escherichia coli OxyR and Bacillus subtilis PerR. Analysis of their regulons has revealed that, in addition to inducible detoxification enzymes, adaptation to H2O2 is mediated by modifications of metal ion homeostasis. Analogous adaptations appear to be present in other bacteria as here reviewed for Deinococcus radiodurans, Neisseria gonorrhoeae, Streptococcus pyogenes, and Bradyrhizobium japonicum. As a general theme, peroxide stress elicits changes in cytosolic metal distribution with the net effect of reducing the damage caused by reactive ferrous iron. Iron levels are reduced by repression of uptake, sequestration in storage proteins, and incorporation into metalloenzymes. In addition, peroxide-inducible transporters elevate cytosolic levels of Mn(II) and/or Zn(II) that can displace ferrous iron from sensitive targets. Although bacteria differ significantly in the detailed mechanisms employed to modulate cytosolic metal levels, a high Mn:Fe ratio has emerged as one key correlate of reactive oxygen species resistance. Antioxid. Redox Signal. 15, 175–189. PMID:20977351

Faulkner, Melinda J.

2011-01-01

308

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

E-print Network

in a rare-earth-metal-ion-doped crystal Lars Rippe, Mattias Nilsson, and Stefan Kröll Department of Physics on optical interactions in rare-earth- metal-ion-doped crystals. The optical transition lines of the rare-earth-metal out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals

Suter, Dieter

309

Metal cation/anion adsorption on calcium carbonate: Implications to metal ion concentrations in groundwater  

SciTech Connect

This chapter evaluates the sorption behavior of metallic ions on specimen calcite as a basis for determining the importance of calcite relative to other subsurface sorbents, such as layer silicates and oxides, in controlling metal ion concentration in calcareous groundwaters. A review of the literature shows the sorption of both metallic cations and anions on calcite over ranges in pH and CO{sub 2} partial pressure to be consistent with a surface-exchange process where cations exchange with surface Ca and anions exchange with surface CO{sub 3}. A general surface-exchange model was developed to account for the effects of Ca and CO{sub 3} concentrations, pH, and calcite surface area on cation and anion sorption onto calcite. The model was applied to recently developed experimental sorption data of Zn and SeO{sub 3} on specimen calcite in equilibrium CaCO{sub 3}(aq) suspensions. The surface-exchange model was able to describe the effects of pH on both cation and anion sorption, and provided good predictions of the effects of variable CO{sub 2}(g) pressure on Zn sorption and of PO{sub 4} on SeO{sub 3} sorption. The surface-exchange model, combined with sorption constants for other phases, was used to calculate Cd sorption to a hypothetical aquifer material containing a mixture of sorbents. The sorbent concentrations were fixed to those expected in groundwater zones. The multi-sorbent calculation documented the importance of calcite as a sorbent for metallic ions in groundwater.93 refs., 18 figs., 5 tabs.

Zachara, J.M.; Cowan, C.E.; Resch, C.T.

1990-05-01

310

Metal Ions, Not Metal-Catalyzed Oxidative Stress, Cause Clay Leachate Antibacterial Activity  

PubMed Central

Aqueous leachates prepared from natural antibacterial clays, arbitrarily designated CB-L, release metal ions into suspension, have a low pH (3.4–5), generate reactive oxygen species (ROS) and H2O2, and have a high oxidation-reduction potential. To isolate the role of pH in the antibacterial activity of CB clay mixtures, we exposed three different strains of Escherichia coli O157:H7 to 10% clay suspensions. The clay suspension completely killed acid-sensitive and acid-tolerant E. coli O157:H7 strains, whereas incubation in a low-pH buffer resulted in a minimal decrease in viability, demonstrating that low pH alone does not mediate antibacterial activity. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to the antibacterial leachate. Further, supplementation with numerous ROS scavengers eliminated lipid peroxidation, but did not rescue the cells from CB-L-mediated killing. In contrast, supplementing CB-L with EDTA, a broad-spectrum metal chelator, reduced killing. Finally, CB-L was equally lethal to cells in an anoxic environment as compared to the aerobic environment. Thus, ROS were not required for lethal activity and did not contribute to toxicity of CB-L. We conclude that clay-mediated killing was not due to oxidative damage, but rather, was due to toxicity associated directly with released metal ions. PMID:25502790

Otto, Caitlin C.; Koehl, Jennifer L.; Solanky, Dipesh; Haydel, Shelley E.

2014-01-01

311

Transition metal ions at the crossroads of mucosal immunity and microbial pathogenesis  

PubMed Central

Transition metal ions are essential micronutrients for all living organisms. In mammals, these ions are often protein-bound and sequestered within cells, limiting their availability to microbes. Moreover, in response to infection, mammalian hosts further reduce the availability of metal nutrients by activating epithelial cells and recruiting neutrophils, both of which release metal-binding proteins with antimicrobial function. Microorganisms, in turn, have evolved sophisticated systems to overcome these limitations and acquire the metal ions essential for their growth. Here we review some of the mechanisms employed by the host and by pathogenic microorganisms to compete for transition metal ions, with a discussion of how evading “nutritional immunity” benefits pathogens. Furthermore, we provide new insights on the mechanisms of host-microbe competition for metal ions in the mucosa, particularly in the inflamed gut. PMID:24478990

Diaz-Ochoa, Vladimir E.; Jellbauer, Stefan; Klaus, Suzi; Raffatellu, Manuela

2013-01-01

312

Transition metal ions at the crossroads of mucosal immunity and microbial pathogenesis.  

PubMed

Transition metal ions are essential micronutrients for all living organisms. In mammals, these ions are often protein-bound and sequestered within cells, limiting their availability to microbes. Moreover, in response to infection, mammalian hosts further reduce the availability of metal nutrients by activating epithelial cells and recruiting neutrophils, both of which release metal-binding proteins with antimicrobial function. Microorganisms, in turn, have evolved sophisticated systems to overcome these limitations and acquire the metal ions essential for their growth. Here we review some of the mechanisms employed by the host and by pathogenic microorganisms to compete for transition metal ions, with a discussion of how evading "nutritional immunity" benefits pathogens. Furthermore, we provide new insights on the mechanisms of host-microbe competition for metal ions in the mucosa, particularly in the inflamed gut. PMID:24478990

Diaz-Ochoa, Vladimir E; Jellbauer, Stefan; Klaus, Suzi; Raffatellu, Manuela

2014-01-01

313

MeRNA: a Database of Metal Ion Binding Sites in RNAStructures  

SciTech Connect

Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA three-dimensional structures available from the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements; in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure, and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering.

Stefan, Liliana R.; Zhang, Rui; Levitan, Aaron G.; Hendrix, DonnaF.; Brenner, Steven E.; Holbrook, Stephen R.

2005-10-05

314

MeRNA: a database of metal ion binding sites in RNA structures  

PubMed Central

Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA 3D structures available from the PDB and Nucleic Acid Database. Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements, in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering. The MeRNA database is accessible at . PMID:16381830

Stefan, Liliana R.; Zhang, Rui; Levitan, Aaron G.; Hendrix, Donna K.; Brenner, Steven E.; Holbrook, Stephen R.

2006-01-01

315

Comparing ceramic-metal to metal-metal total hip replacements--a simulator study of metal wear and ion release in 32- and 38-mm bearings.  

PubMed

Our 32 and 38 mm alumina ceramic-on-metal (COM) bearings were run in a hip simulator study for comparison with 32 mm metal-on-metal (MOM) controls. The 32 mm MOM bearings demonstrated an overall wear rate of 1.58 mm(3)/million cycles (Mc) that was comparable to previous simulator studies. The peak run-in MOM wear-rates (10, 15.7 mm(3)/Mc) were higher than in previous simulator studies. There was a noticeable graying in color of serum lubricants with MOM wear rates of 2-3 mm(3)/Mc and with wear rates of 10-15 mm(3)/Mc the serum became much darker. The COM lubricants darkened during two "break-away" wear events with wear-rates 5.8-6.7 mm(3)/Mc. The 32 and 38 mm COM bearings demonstrated overall wear-rates of 0.38 and 0.29 mm(3)/Mc, approximately four-fold reduced compared to MOM controls. The COM wear-rates were also much higher than in the one previous COM study. There may be methodological reasons that could explain this discrepancy. Our ion concentrations assessed from serum lubricants had Cobalt (Co) 68% and Chromium (Cr) 32% for average ratio of metal ion composition (i.e. averaging Co/Cr ratios: 2.26) in the parent alloy. Comparing Co ion concentrations during run-in, the COM bearings represented a 35-fold reduction compared to MOM. At 3.0 Mc, the COM represented a 33-fold reduction compared to MOM. Overall, our simulator study confirmed previously published advantages of low wear and reduced metal ions with the ceramic-metal coupling compared to standard metal-metal bearings. PMID:19598291

Ishida, Tsunehito; Clarke, Ian C; Donaldson, Thomas K; Shirasu, Hideo; Shishido, Takaaki; Yamamoto, Kengo

2009-11-01

316

Grid-controlled metal ion sources for heavy ion fusion accelerators  

NASA Astrophysics Data System (ADS)

A variety of metal ions can be generated using vacuum arcs, but due to the nature of these arcs, the flux generated fluctuates in time. We have successfully employed electrostatically biased grids to control the plasma and to provide a well-behaved, space charge limited ion source. The grid prevents the plasma from entering the extraction gap before the main voltage pulse is applied. The extracte ion is space charge limited, resulting in a constant output current even though the ion flux from the vacuum arc source varies considerably. There are several advantages over conventional sources. For instance, thermionic sources are faced with heating problems for large area configurations, while gas-injection sources cause prefill problems because they take too long to reach equilibrium. We have performed extraction experiments with aluminum and indium arc sources. We have extracted 300 mA of pure Al+ at 30 kV for 10 ?s. The normalized beam emittance has been measured to be 3×10-7 ?-m-rad.

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

1986-01-01

317

High current liquid metal ion source using porous tungsten multiemitters.  

PubMed

We recently developed an indium Liquid-Metal-Ion-Source that can emit currents from sub-?A up to several mA. It is based on a porous tungsten crown structure with 28 individual emitters, which is manufactured using Micro-Powder Injection Molding (?PIM) and electrochemical etching. The emitter combines the advantages of internal capillary feeding with excellent emission properties due to micron-size tips. Significant progress was made on the homogeneity of the emission over its current-voltage characteristic as well as on investigating its long-term stability. This LMIS seems very suitable for space propulsion as well as for micro/nano manufacturing applications with greatly increased milling/drilling speeds. This paper summarizes the latest developments on our porous multiemitters with respect to manufacturing, emission properties and long-term testing. PMID:21111260

Tajmar, M; Vasiljevich, I; Grienauer, W

2010-12-01

318

Highly charged Ar{sup q+} ions interacting with metals  

SciTech Connect

Using computer simulation, alternative methods of the interaction of highly charged ions Ar{sup q+} with metals (Au, Ag) are used and verified in the present work. Based on the classical over-barrier model, we discussed the promotion loss and peeling off processes. The simulated total potential electron yields agree well with the experiment data in incident energy ranging from 100 eV to 5 keV and all charge states of Ar{sup q+}. Based on the TRIM code, we obtain the side-feeding rate as well as the motion and charge transfer of HCI below the surface. Some results, including the array of KL{sup x} x-ray satellite lines, the respective contribution of autoionization, and side-feeding to inner shells, and the filling rates and lifetime of inner shells for Ar agree well with experiment or theory.

Wang Jijin; Zhang Jian; Gu Jiangang; Luo Xianwen; Hu Bitao [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China)

2009-12-15

319

Highly Emissive Transition Metal Ion Doped Semiconducting Nanocrystals  

SciTech Connect

Doped semiconductor nanocrystals (d-dots), specifically ones not containing heavy metal ions, have the potential to become a class of mainstream emissive materials. Mn- and Cu-doped ZnSe or ZnS d-dots can cover an emission window similar to that of the current workhorse of intrinsic quantum dot (q-dots) emitters, CdSe nanocrystals. We synthesized high quality stable Cu doped ZnSe in nonpolar as well as polar solvent. The emission intensity of these doped nanocrystals is found stable for months under UV irradiation, after different multifunctional ligand which is important for any biological detection. We have also synthesized the stable Mn doped ZnS in nonpolar solvent more than 50% QY.. The doped nanocrystals are characterized by TEM, XRD, EPR and ICP analysis.

Jana, Santanu; Srivastava, Bhupendra B.; Pradhan, Narayan [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Sarma, D. D. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore (India)

2011-07-15

320

Specific chemical interactions between metal ions and biological solids exemplified by sludge particulates.  

PubMed

The adsorption of metals onto biological surfaces was studied exemplified by municipal sludge particulates of the primary, the secondary, and the tertiary sludge types from four regional wastewater treatment plants. Major factors affecting the extent of metal adsorption including pH, DOM, total biomass, and total metal loading were studied. The acidity-basicity characteristics of the DOM, the metal ions (Lewis acids), and the surface of the sludge particulates make pH the most important parameter in metal adsorption. Change in pH can modify the speciation of the metal ions, the DOM, and the surface acidity of the sludge particulates and subsequently determines the degree of metal distribution between the aqueous phase and the sludge solids. Information on the acidity-basicity characteristics of the DOM and the sludge particulates are used to calculate the stability constant of metal ion-sludge complexes. PMID:24495800

Huang, C P; Wang, Jianmin

2014-05-01

321

Removal of Toxic\\/Heavy Metal Ions Using Ion-Imprinted Aminofunctionalized Silica Gel  

Microsoft Academic Search

The investigation reports the preparation and evaluation of Cr(III) and Fe(III)-imprinted amino-functionalized silica gel adsorbents (APTS-Cr(III)-Si and APTS-Fe(III)-Si) for selective solid-phase extraction of Cr(III) and Fe(III), respectively, from aqueous solutions. The adsorbent materials were prepared by a surface imprinting technique using 3-aminopropyltrimethoxysilane as the surface modifying ligand. The effects of solution pH, sorption time, temperature, and initial metal ion concentration

R. K. Dey; Usha Jha; Tanushree Patnaik; A. C. Singh; Varun K. Singh

2009-01-01

322

Engineering metal ion coordination to regulate amyloid fibril assembly and toxicity  

E-print Network

Engineering metal ion coordination to regulate amyloid fibril assembly and toxicity Jijun Dong, Athens, GA 30602; and §Departments of Pharmacology and Neurology, Emory University School of Medicine13 and H14 implicated in A -metal ion binding, we show that Cu2 forms complexes with A (13

Scott, Robert A.

323

Biosorption of heavy metal ions from aqueous solution by red macroalgae  

Microsoft Academic Search

Biosorption is an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine algae has been reported to have high biosorption capacities for a number of heavy metal ions. In this study, four species of red seaweeds Corallina mediterranea, Galaxaura oblongata, Jania rubens and Pterocladia capillacea were examined to remove Co(II), Cd(II),

Wael M. Ibrahim

2011-01-01

324

The Mutation F227I Increases the Coupling of Metal Ion Transport in DCT1*  

E-print Network

in Xenopus oocyte (5­9). Xenopus oocytes have a very low metal ion uptake background, which makes them the ideal heterolo- gous expression system for metal ion transporters. In addition to the uptake--Oligonucleotide-directed, site- specific mutagenesis was performed by overlapping nucleotides with the mutation

Nelson, Nathan

325

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

326

Functional characterization and metal ion specificity of the metal-citrate complex transporter from Streptomyces coelicolor.  

PubMed

Secondary transporters of citrate in complex with metal ions belong to the bacterial CitMHS family, about which little is known. The transport of metal-citrate complexes in Streptomyces coelicolor has been investigated. The best cofactor for citrate uptake in Streptomyces coelicolor is Fe(3+), but uptake was also noted for Ca(2+), Pb(2+), Ba(2+), and Mn(2+). Uptake was not observed with the Mg(2+), Ni(2+), or Co(2+) cofactor. The transportation of iron- and calcium-citrate makes these systems unique among the CitMHS family members reported to date. No complementary uptake akin to that observed for the CitH (Ca(2+), Ba(2+), Sr(2+)) and CitM (Mg(2+), Ni(2+), Mn(2+), Co(2+), Zn(2+)) systems of Bacillus subtilis was noted. Competitive experiments using EGTA confirmed that metal-citrate complex formation promoted citrate uptake. Uptake of free citrate was not observed. The open reading frame postulated as being responsible for the metal-citrate transport observed in Streptomyces coelicolor was cloned and overexpressed in Escherichia coli strains with the primary Fe(3+)-citrate transport system (fecABCDE) removed. Functional expression was successful, with uptake of Ca(2+)-citrate, Fe(3+)-citrate, and Pb(2+)-citrate observed. No free-citrate transport was observed in IPTG (isopropyl-beta-d-thiogalactopyranoside)-induced or -uninduced E. coli. Metabolism of the Fe(3+)-citrate and Ca(2+)-citrate complexes, but not the Pb(2+)-citrate complex, was observed. Rationalization is based on the difference in metal-complex coordination upon binding of the metal by citrate. PMID:18556792

Lensbouer, Joshua J; Patel, Ami; Sirianni, Joseph P; Doyle, Robert P

2008-08-01

327

A lithium liquid metal ion source suitable for high voltage terminal applications  

SciTech Connect

Liquid metal ion sources offer potential improvement in lateral resolution over conventionally used gaseous sources for MeV microprobe applications because of their intrinsic brightnesses. The use of a Li liquid metal ion source is particularly attractive because of the increased sensitivity of lithium for detecting hydrogen (hydrogen profiling) and for detecting near surface contaminants through high-resolution Rutherford backscattering spectrometry. However, the technical difficulty of occasional sparking between the needle and extraction electrode requires that the needle of the Li liquid metal ion source be rewetted before reignition can be effected; this problem makes Li liquid metal ion sources of the usual design risky for operation in the insulated high-voltage terminals of accelerators used in such applications. We have designed a reliable, long-lived, Li liquid-metal ion source which has provisions for overcoming this limitation. The design features and performance characteristics of the source are described in this report. 9 refs., 4 figs.

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

1989-01-01

328

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

PubMed

Herein, a small-molecule fluorescent sensor array for rapid identification of seven heavy metal ions was designed and synthesized, with its sensing mechanism mimicking that of a tongue. The photoinduced electron transfer and intramolecular charge transfer mechanism result in combinatorial interactions between sensor array and heavy metal ions, which lead to diversified fluorescence wavelength shifts and emission intensity changes. Upon principle component analysis (PCA), this result renders clear identification of each heavy metal ion on a 3D spatial dispersion graph. Further exploration provides a concentration-dependent pattern, allowing both qualitative and quantitative measurements of heavy metal ions. On the basis of this information, a "safe-zone" concept was proposed, which provides rapid exclusion of versatile hazardous species from clean water samples based on toxicity characteristic leaching procedure standards. This type of small-molecule fluorescent sensor array could open a new avenue for multiple heavy metal ion detection and simplified water quality analysis. PMID:25144824

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

2014-09-01

329

Controlled aggregation of gold nanoparticle networks induced by alkali metal ions.  

PubMed

Gold nanoparticle networks were obtained by linking them with cysteine modified triethyleneglycols. The oligo-ether linker molecule initially having a linear structure probably adopts a crown ether type structure upon complexation with alkali metal ions that leads to a controlled aggregation of the network. The extent of aggregation depends on the degree of conformational change in the molecule upon complexation with the metal ion, which in turn is governed by the metal ion radius leading to a dependence of red shift of the surface plasmon resonance on the metal ion radius. Since this network is present in the organic solvent they also act as phase transferring agent for the alkali metal ions from aqueous to organic media. PMID:17685284

Tamang, Sudarsan; Hotha, Srinivas; Prasad, B L V

2007-08-01

330

Reactions of metal ions at surfaces of hydrous iron oxide  

USGS Publications Warehouse

Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

Hem, J.D.

1977-01-01

331

Attenuation of divalent toxic metal ions using natural sericitic pyrophyllite.  

PubMed

The present study investigated the effectiveness of an inexpensive and ecofriendly alumino silicate clay mineral, sericitic pyrophyllite, as an adsorbent for the possible application in the removal of some divalent toxic metal cations such as Pb(2+), Cu(2+)and Zn(2+) from aqueous systems. Batch scale equilibrium adsorption studies were carried out for a wide range of initial concentration from 24.1 to 2,410 micromol L(-1) for lead, 78.65 to 7,865 micromol L(-1) for copper and 76.45 to 7,645 micromol L(-1) for zinc solutions. The removal of Pb(2+) was almost complete at low concentration (maximum lead removal capacity, LRC, 32 mg of lead/g of pyrophyllite) with 10 g L(-1) of adsorbent in a 30 min equilibration time. The effects of temperature on adsorption of heavy metal ions were studied. The applicability of the Langmuir, Freundlich and Dubinin-Radushkevich adsorption models in each case of lead, copper and zinc adsorption was examined separately at different temperatures. The adsorption process was found to be endothermic and the Freundlich adsorption model was found to represent the data at different temperatures more suitably. PMID:17764819

Prasad, Murari; Saxena, Sona

2008-09-01

332

Effect of coexisting alkaline metal ions on the extraction selectivity of lanthanide ions with calixarene car?ylate derivatives  

Microsoft Academic Search

Extraction behavior of nine types of trivalent lanthanide ions from three types of aqueous solutions containing an alkaline metal ion such as lithium, sodium or potassium ion into chloroform was investigated with three types of extractants: 37, 38, 39, 40, 41, 42-hexakis(car?ymethoxy)-5, 11, 17, 23, 29, 35-hexakis(1, 1, 3, 3-tetramethylbutyl)calix[6]arene and the cone conformational type of 25, 26, 27, 28-tetrakis(car?ymethoxy)-5,

Keisuke Ohto; Masayuki Yano; Katsutoshi Inoue; Takeshi Nagasaki; Masahiro Goto; Fumiyuki Nakashio; Seiji Shinkai

1997-01-01

333

Post-synthesis addition of transition metal ions and lanthanide ions to the surface of anatase titanium (IV) dioxide nanorods  

NASA Astrophysics Data System (ADS)

Solar energy utilization is an attractive option for new energy technology and economic development. Our research is the formulation of catalyst materials for solar production of hydrogen from water. Titanium(IV) oxide has been explored for water splitting; however, a major challenge is that titanium(IV) oxide can only absorb UV light. Visible light absorption can be increased by metal ion or anion doping by creating interband states. Most dopant protocols lead to deposition of dopant ions throughout the solid, and interfacial deposition has received very little attention. We have developed a method to selectively attach transition metal ions and lanthanide ions on the surface of titanium(IV) oxide nanorods using metal chlorides as precursors. The present study demonstrates that Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu (II), Eu(III), Ce(III), Pr(III) and Er(III) were coordinated to the surface of oleic acid capped TiO2 nanorods (NRs) by post-synthesis method without any phase or morphology transformation. Metal ion loading could be carefully controlled, and we show a titration curve for addition of transition metal ions and Eu(III) to the nanorod surface. The materials were characterized with UV-visible spectroscopy, transmission electron microscopy, elemental analysis, XPS and powder X-ray diffraction. X-ray photoelectron spectra were obtained for a series of M-TiO2 samples in which transition metal (M = Cr, Mn, Fe, Co, Ni, Cu) ions are directly attached to the surface of anatase TiO2 nanocrystals. Further, we report sequential, quantitative loading of transition metal ions (Cr, Mn, Fe, Co, Ni, Cu) to the surface of rod-shape anatase TiO2 nanocrystals in bimetallic combinations (6C2 = 15). TEM, PXRD, UV-Vis, XPS and elemental analysis characterization show that bimetallic combinations were synthesized successfully.

Balasanthiran, Choumini

334

METAL INTERACTIONS AT SULFIDE MINERAL SURFACES: PART 3, METAL AFFINITIES IN SINGLE AND MULTIPLE ION ADSORPTION REACTIONS  

EPA Science Inventory

Adsorption reactions of both single ions and multiple ion mixtures with sulfide minerals (chalcocite, galena, pyrite, and sphalerite) were investigated in the metal concentration range of 0.0001 to 0.00001 M. Chromium (III), iron (III), barium (II), cadmium (II), copper (II), nic...

335

Synthesis and characterization of lanthanum dicarbide-carbon targets for radioactive ion beams generation via the carbothermal reaction  

Microsoft Academic Search

In this study, we report the synthesis procedure for the attainment of thin pellets composed of lanthanum dicarbide (LaC2) grains and graphite, as a candidate material for the production of targets for the generation of radioactive ion beams (RIBs). The samples were obtained by thermal treatment of green pellets of lanthanum oxide or lanthanum oxalate (La2O3 and La2(C2O4)3, respectively) mixed

S. Carturan; M. Tonezzer; L. Piga; P. Zanonato; P. Colombo; A. Andrighetto; L. Biasetto; P. Di Bernardo; G. Maggioni; F. Gramegna; G. Prete

2007-01-01

336

Effect of heavy metal ion excess on sunflower leaves: evidence for involvement of oxidative stress  

Microsoft Academic Search

The relationship between heavy metal ion toxicity and oxidative stress in plant cells was studied. Leaf segments from 14 day old sunflower seedlings were incubated in solutions containing 0.5 mM Fe(II), Cu(II) or Cd(II) ions for 12 h in the light. Treatment with metal ions studied produced a decrease in chlorophyll and GSH contents as well as increases in lipid

Susana M. Gallego; María P. Benavídes; María L. Tomaro

1996-01-01

337

Role of oxide surface in coordination chemistry of transition metal ions in catalytic systems  

Microsoft Academic Search

On going from the solution into the bulk of an oxide through the fluid-solid interface, it is possible to encounter four types of coordina- tion chemistry (CC) for a transition metal ion (TMI) : solution coordina- tion chemistry, extraframework ion CC, surface framework ion CC and solid state CC. In each case, the reactivity of the TMI is discussed on

L. Bonneviot; M. Curie

1988-01-01

338

Magic Numbers and Critical Sizes of Tin Clusters Emitted from a Liquid Metal Ion Source  

Microsoft Academic Search

Sn cluster ions from a liquid metal ion source have been analyzed by mass spectrometry. Discontinuous variations in ion intensity as a function of the cluster size were found at n{=}4 and 6 (magic numbers) for singly charged clusters, where n is the number of atoms contained in the cluster. By comparing this with other studies for Si, Ge, and

Makoto Watanabe; Yahachi Saito; Satoshi Nishigaki; Tamotsu Noda

1988-01-01

339

In-line nitrogen PIII/ion nitriding processing of metallic materials  

E-print Network

In-line nitrogen PIII/ion nitriding processing of metallic materials M. Ueda a,*, G.F. Gomes a , E cathode nitrogen glow discharges with 600­1000 V, 50­300 mA were typically obtained using the sample power avail- able), we are studying a hybrid process using nitrogen PIII with ion nitriding. Ion

340

Prediction of Metal Ion–Binding Sites in Proteins Using the Fragment Transformation Method  

PubMed Central

The structure of a protein determines its function and its interactions with other factors. Regions of proteins that interact with ligands, substrates, and/or other proteins, tend to be conserved both in sequence and structure, and the residues involved are usually in close spatial proximity. More than 70,000 protein structures are currently found in the Protein Data Bank, and approximately one-third contain metal ions essential for function. Identifying and characterizing metal ion–binding sites experimentally is time-consuming and costly. Many computational methods have been developed to identify metal ion–binding sites, and most use only sequence information. For the work reported herein, we developed a method that uses sequence and structural information to predict the residues in metal ion–binding sites. Six types of metal ion–binding templates– those involving Ca2+, Cu2+, Fe3+, Mg2+, Mn2+, and Zn2+–were constructed using the residues within 3.5 Å of the center of the metal ion. Using the fragment transformation method, we then compared known metal ion–binding sites with the templates to assess the accuracy of our method. Our method achieved an overall 94.6 % accuracy with a true positive rate of 60.5 % at a 5 % false positive rate and therefore constitutes a significant improvement in metal-binding site prediction. PMID:22723976

Lu, Chih-Hao; Lin, Yu-Feng; Lin, Jau-Ji; Yu, Chin-Sheng

2012-01-01

341

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

NASA Astrophysics Data System (ADS)

Chemistry in the interstellar medium is very different from the processes which take place in terrestrial settings. Environments such as circumstellar envelopes, molecular clouds, and comets contain diverse and complex chemical networks. The low temperatures (10 50 K) and densities (1 10 6 cm-3) allow normally unstable molecules to exist in significant quantities. At these temperatures, the rotational energy levels of molecules are populated, and thus these species can be detected by millimeter-wave radio astronomy. The detection and quantification of interstellar molecules, including metal cyanides and molecular ions, is the basis of this dissertation work. While conducting observations of CN and 13CN to determine the 12C/13C ratio throughout the Galaxy, it was found that the ratios in photon- dominated regions (PDRs) were much higher than those in nearby molecular clouds. This can be explained by isotope-selective photodissociation, in which the 12CN molecules are self-shielded. However, the chemistry in these regions is poorly understood, and other processes may be occurring. In order to understand one of the chemical networks present in PDRs, observations of HCO+, HOC +, and CO+ were made toward several of these sources. Previous studies indicated that the HCO+/HOC+ ratio was much lower in PDRs, due to the presence of CO+. The new observations indicate that there is a strong correlation between CO + and HOC+ abundances, which suggests that other molecular ions which have not been detected in molecular clouds may be present in PDRs. There is a significant obstacle to the detection of new interstellar molecular ions, however. The laboratory spectra are virtually unknown for many of these species, due to their inherent instability. Thus, techniques which can selectively detect ionic spectra must be utilized. One such method is velocity modulation, which incorporates an AC electrical discharge to produce and detect ions. Previously, velocity modulation spectroscopy was employed only at infrared wavelengths. The final phase of this dissertation work was to design, build and test a velocity modulation spectrometer which functions at millimeter/sub-mm wavelengths. This system was then used to measure the previously unknown pure rotational spectrum of SH+ (X3E- ).

Savage, Chandra Shannon

2004-11-01

342

Electron stimulated desorption of alkali metal ions and atoms: Local surface field relaxation  

Microsoft Academic Search

Electron stimulated desorption (ESD) of neutral alkali metal atoms and positive ions has been studied from alkali metal layers adsorbed on oxidized and silicided tungsten by means of a static magnetic mass spectrometer combined with a retarding field analizer. The desorbed alkali metal atoms were ionized in a surface ionization detector and their energy distributions were measured using a time-of-flight

V. N. Ageev; Yu. A. Kuznetsov; B. V. Yakshinskii; T. E. Madey

1995-01-01

343

Development of a metal recovery process from Li-ion battery wastes  

Microsoft Academic Search

A process for the recovery of lithium and cobalt from the waste of lithium ion batteries using sulfuric acid and hydrogen peroxide was proposed, and metal leaching performance was investigated. The proposed procedure consisted of mechanical separation of metal-containing particles and a chemical leaching process. The effects of leaching agent, of the size of metal-bearing particles, and of incineration as

Shun Myung Shin; Nak Hyoung Kim; Jeong Soo Sohn; Dong Hyo Yang; Young Han Kim

2005-01-01

344

Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems  

PubMed Central

Background The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems. Methods In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr. Results Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs. Conclusions When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system. PMID:24472283

2014-01-01

345

Metal salts for molecular ion yield enhancement in organic secondary ion mass spectrometry: a critical assessment.  

PubMed

In a search for molecular ion signal enhancement in organic SIMS, the efficiency of a series of organic and inorganic salts for molecular cationization has been tested using a panel of nonvolatile molecules with very different chemical characteristics (leucine enkephalin, Irganox 1010, tetraphenylnaphthalene, polystyrene). The compounds used for cationization include alkali bromide and group Ib metal salts (XBr with X = Li, Na, K; CF3CO2Ag; AgNO3; [CH3COCH=C(O-)CH3]2Cu; AuCl3). Alkali ions, very good for polar molecule cationization, prove to be of limited interest for nonpolar molecules such as polystyrene. Silver trifluoroacetate displays excellent results for all the considered molecules, except for leucine enkephalin (which might be due to the use of different solvents for the analyte and the salt). Instead, silver nitrate mixed with leucine enkephalin in an ethanol solution provides intense molecular signals. The influence of the respective concentrations of analyte and salt in solution, of the silver trifluoroacetate solution stability, and of the sample microstructure on the secondary ion intensities are also investigated. The results of other combinations of analyte and salts are reported. Finally, the use of salts is critically compared to other sample preparation procedures previously proposed for SIMS analysis of large organic molecules. PMID:15801744

Delcorte, A; Bertrand, P

2005-04-01

346

Radioactive scrap metal (RSM) inventory & tracking system and prototype RSM field survey  

SciTech Connect

Based on very preliminary information, it has been estimated that the radioactive scrap metal (RSM) inventories at DOE facilities amount to about 1.5 million tons and a much larger amount will be generated from decontamination and decommissioning of surplus DOE facilities. To implement a national DOE program for beneficial reuse of RSM, it will be necessary to known the location and characteristics of RSM inventories that are available and will be generated to match them with product demands. It is the intent of this task to provide a standardized methodology via a RSM database for recording, tracking, and reporting data on RSM inventories. A multiple relational database in dBASE IV was designed and a PC-based code was written in Clipper 5.0 syntax to expedite entry, editing, querying, and reporting of RSM survey data. The PC based-code, the multiple relational database files, and other external files used by the code to generate reports and queries constitute a customized software application called the RSM Inventory & Tracking System (RSM I&TS). A prototype RSM field survey was conducted at the Nevada Test Site (NTS) to demonstrate the field use of the RSM I&TS and logistics of conducting the survey. During the demonstration, about 50 tons of RSM were sized, characterized, sorted, and packaged in transport containers.

Thomas, T.R.

1994-09-01

347

Nondestructive decontamination of mortar and concrete by electro-kinetic methods: application to the extraction of radioactive heavy metals.  

PubMed

Because the service lives of nuclear power plants are limited to a certain number of years, the need for the management of quite a large volume of radioactive contaminated concrete arises, which, in most cases, was not taken into account when the capacities of the low and medium activity repositories were designed. Therefore, the decontamination of these structures would be of great interest in order to declassify the wastes as radioactive and manage them as conventional ones. This research studies the reliability of the application of electrical fields to decontaminate radioactive contaminated concrete. Three series of decontamination experiments have been carried out, using Cs+, Sr2-, Co2+, and Fe3+ ions added during casting and that have penetrated from the outside, testing carbonated and uncarbonated matrixes, and using laboratory devices as well as the homemade device for in situ application named "honeycomb device". As a result, the application of electrical fields to concrete-contaminated structures has been developed as a new technique to extract radioactive ionic species from concrete. This method of decontamination has been patented by ENRESA (Spanish Company for the Management of Radioactive Wastes) in association with the IETcc. PMID:12038838

Castellote, Marta; Andrade, Carmen; Alonso, Cruz

2002-05-15

348

C H A P T E R F I V E Metal Ion-Based RNA Cleavage  

E-print Network

* and Daniel Herschlag Contents 1. Introduction 92 2. Mechanisms of Metal Ion-Based Cleavage of Nucleic Acids- sphere'') neutralize the negative charge present on the phosphodiester backbone, allowing nucleic acids be obtained using other techniques. 2. Mechanisms of Metal Ion-Based Cleavage of Nucleic Acids Metal ions

Herschlag, Dan

349

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

PubMed Central

Introduction The use of metal-on-metal (MoM) total hip arthroplasty (THA) increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds) in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. Objective To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. Methods Systematic review of clinical trials (RCTs) and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum) in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor), patient characteristics as well as study quality characteristics (secondary explanatory factors). Results Overall, 104 studies (11 RCTs, 93 epidemiological studies) totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine) irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L). Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. Discussion Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed „time out“ for stemmed large-head MoM-THA and recommend a restricted indication for hip resurfacing arthroplasty. Patients with implanted MoM-bearing should receive regular and standardized monitoring of metal ion concentrations. Further research is indicated especially with regard to potential systemic reactions due to accumulation of metal products. PMID:23950923

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

2013-01-01

350

Computational scheme for the prediction of metal ion binding by a soil fulvic acid  

USGS Publications Warehouse

The dissociation and metal ion binding properties of a soil fulvic acid have been characterized. Information thus gained was used to compensate for salt and site heterogeneity effects in metal ion complexation by the fulvic acid. An earlier computational scheme has been modified by incorporating an additional step which improves the accuracy of metal ion speciation estimates. An algorithm is employed for the prediction of metal ion binding by organic acid constituents of natural waters (once the organic acid is characterized in terms of functional group identity and abundance). The approach discussed here, currently used with a spreadsheet program on a personal computer, is conceptually envisaged to be compatible with computer programs available for ion binding by inorganic ligands in natural waters.

Marinsky, J.A.; Reddy, M.M.; Ephraim, J.H.; Mathuthu, A.S.

1995-01-01

351

Effects of metal ions on growth, ?-oxidation system, and thioesterase activity of Lactococcus lactis.  

PubMed

The effects of divalent metal ions (Ca(2+), Mg(2+), Fe(2+), and Cu(2+)) on the growth, ?-oxidation system, and thioesterase activity of Lactococcus lactis were investigated. Different metal ions significantly influenced the growth of L. lactis: Ca(2+) and Fe(2+) accelerated growth, whereas Cu(2+) inhibited growth. Furthermore, Mg(2+) inhibited growth of L. lactis at a low concentration but stimulated growth of L. lactis at a high concentration. The divalent metal ions had significant effects on activity of the 4 key enzymes of the ?-oxidation system (acyl-CoA dehydrogenase, enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and thiolase) and thioesterase of L. lactis. The activity of acyl-CoA dehydrogenases increased markedly in the presence of Ca(2+) and Mg(2+), whereas it decreased with 1 mmol/L Fe(2+) or 12 mmol/L Mg(2+). All the metal ions could induce activity of enoyl-CoA hydratase. In addition, 12 mmol/L Mg(2+) significantly stimulated activity of L-3-hydroxyacyl-CoA dehydrogenase, and all metal ions could induce activity of thiolase, although thiolase activity decreased significantly when 0.05 mmol/L Cu(2+) was added into M17 broth. Inhibition of thioesterase activity by all 4 metal ions could be reversed by 2 mmol/L Ca(2+). These results help us understand the effect of metal ions on the ?-oxidation system and thioesterase activity of Lactococcus lactis. PMID:25064652

Li, Liang; Ma, Ying

2014-10-01

352

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

NASA Astrophysics Data System (ADS)

It is generally accepted, that metal transport in natural aquatic systems strongly de- pends on the metal binding form. Besides complex formation with well defined inor- ganic and organic ligands, the interaction with colloidal particles and soil material is one of the most important reactions of metal ions in aquatic systems. Mobile colloids compete with the stationary soil matrix for binding of metal ions and might facili- tate their transport. Important representatives for mineral and organic colloids are clay minerals and natural organic matter (NOM), respectively. In this work, the interaction of metal ions with clay minerals and NOM is characterized by coupling of asymmetric flow field-flow fractionation AF4 to inductively coupled plasma ­ mass spectrometry (ICPMS). A method for separating mineral from organic colloids is presented, which allows to quantify the amount of metals being bound to either colloid. For different metal ions (Cu, Zn, Pb, Pt) and a metalloid (As) a different extent of binding to either colloid was found.The information obtained from the AF4-ICPMS measurements was useful for the understanding of the observations from column experiments which were conducted to quantify the colloid-facilitated metal transport. In column experiments, the transport of the mineral colloids itself and the influence of NOM onto the colloid transport were investigated. Furthermore, the dependance of colloid transport from the ionic strength and the pH value was elucidated. In order to get information about the co-transport of metal ions by organic and mineral colloids, metal ions were adsorbed onto the colloidal material and a distribution coef- ficient of the metal ions between the colloidal phase and the solution was determined. The colloidal suspension containing both, "free" and adsorbed metal ions were then injected onto the column. The direct metal breakthrough caused by colloidal trans- port was detected at the column outlet. The results clearly revealed that the amount of metal ions being transported agreed well with the amount of colloids being mobile and the amount of metal ions being bound to the colloids. Particle mobility is strongly affected by the ionic strength of the eluent and by organic coatings. In the presence of NaCl organic coatings enhanced particle mobility, whereas in the presence of CaCl2 it was reduced.

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

353

Influence of Metal Ions on the Conductivity of Nafion 112 in Polymer Electrolyte Membrane Fuel Cell  

SciTech Connect

Nafion 112 membranes were soaked in 1 M H2SO4 solutions containing variable amounts of Fe and Cr ions, either individually or mixed. An even distribution of the metal ions on the surface of the membranes was observed with electron probe microanalysis (EPMA) mapping. The proton conductivity of the soaked membranes was investigated using a conductivity cell. For Fe ions, the conductivity was almost constant until the Fe-ion solution concentration reached 300 ppm. Over the 300-ppm threshold, the conductivity decreased significantly. Similar results were obtained with Cr ions in the membrane, but here the threshold was approximately 200 ppm in the solution. Mixed metal ions were found to decrease these threshold values due to the additive effect of the two metals.

Wang, H.; Turner, J.

2008-01-01

354

Coordination numbers of alkali metal ions in aqueous solutions  

Microsoft Academic Search

The level of complexity with which any biological ion interaction mechanism can be investigated, whether it is a binding mechanism in proteins or a permeation mechanism in ion channels, is invariably limited by the state-of-the-art of our understanding of the characteristic properties of ion solvation. Currently, our understanding of the energetic properties of ion solvation in aqueous phase is considered

Sameer Varma; Susan B. Rempe

2006-01-01

355

Trace enrichment and separation of metal ions as dithiocarbamate complexes by liquid chromatography  

Microsoft Academic Search

A method is presented that involves the simultaneous formation of metal dithiocarbamates and on-line preconcentration and, subsequently, separation of heavy-metal ions (Cd(II), Pb(II), Hg(II), Cu(II), Co(II), Ni(II), Bi(III)) by reversed-phase liquid chromatography. A cetrimide-dithiocarbamate ion pair is loaded onto a precolumn packed with Cââ-bonded silica, and the injected metal ions react instantaneously with the dithiocarbamate to form stable complexes. These

Hubertus. Irth; G. J. de Jong; U. A. Th. Brinkman; R. W. Frei

1987-01-01

356

Sugar-metal ion interactions: the complicated coordination structures of cesium ion with D-ribose and myo-inositol.  

PubMed

The novel cesium chloride-D-ribose complex (CsCl·C5H10O5; Cs-R) and cesium chloride-myo-inositol complex (CsCl·C6H12O6; Cs-I) have been synthesized and characterized using X-ray diffraction and FTIR, FIR, THz, and Raman spectroscopy. Cs(+) is eight-coordinated to three chloride ions, O1 and O2 from one D-ribose molecule, O1 from another D-ribose molecule, and O4 and O5 from the third D-ribose molecule in Cs-R. For one D-ribose molecule, the oxygen atom O1 in the ring is coordinated to two cesium ions as an oxygen bridge, O2 is cocoordinated with O1 to one of the two cesium ions, and O4 and O5 are coordinated to the third cesium ion, respectively. O3 does not coordinate to metal ions and only takes part in forming hydrogen bonds. One chloride ion is connected to three cesium ions. Thus, a complicated structure of Cs-D-ribose forms. For Cs-I, Cs(+) is 10-coordinated to three chloride ions, O1 and O2 from one myo-inositol molecule, O3 and O4 from another myo-inositol molecule, O5 and O6 from the third myo-inositol molecule, and O6 from the fourth myo-inositol molecule. One metal ion is connected to four ligands, and one myo-inositol is coordinated to four Cs(+) ions, which is also a complicated coordination structure. Crystal structure results, FTIR, FIR, THz, and Raman spectra provide detailed information on the structure and coordination of hydroxyl groups to metal ions in the cesium chloride-D-ribose and cesium chloride-myo-inositol complexes. PMID:24175895

Hu, Haijian; Xue, Junhui; Wen, Xiaodong; Li, Weihong; Zhang, Chao; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Bu, Xiaoxia; Liu, Kexin; Chen, Jia'er; Wu, Jinguang

2013-11-18

357

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

358

Novel Metal Ion Based Estrogen Mimics for Molecular Imaging  

SciTech Connect

The overall objective of the SBIR Phase I proposal is to prepare and evaluate a new class of {sup 99m}Tc or {sup 94m}Tc containing estrogen-like small molecules ('estrogen mimics') for SPECT or PET molecular imaging of estrogen receptor positive (ER+) tumors. In this approach, the metal ion is integrated into the estrone skeleton by isosteric substitution of a carbon atom in the steroidal structure to give new class of mimics that are topologically similar to the native estrogen (Fig. 1). Although both N{sub 2}S{sub 2} and N{sub 3}S mimics 1 and 2 were considered as target structures, molecular modeling study revealed that the presence of the acetyl group at position-15 in the N{sub 3}S mimic 2 causes steric hinderance toward binding of 2 to SHBG. Therefore, initial efforts were directed at the synthesis and evaluation of the N{sub 2}S{sub 2} mimic 1.

Rajagopalan, Raghavan

2006-01-30

359

Sputtering of parent-like ions from large organic adsorbates on metals under keV ion bombardment  

NASA Astrophysics Data System (ADS)

Thin films of hydrocarbon molecules, unsaturated fatty acid and low molecular weight polystyrene deposited on different metal substrates (silver, copper and gold) were bombarded by 15 keV Ga ions and the secondary ions were mass- and energy-analysed by means of a time-of-flight secondary ion mass spectrometer. The samples were studied in order to evidence the effects of different substrates and coverages on the emission of the parent and cationised molecular ions, and to gain a better understanding of the large molecular ion emission processes. Ion beam degradation studies were realised for fundamental purposes too. In general, the kinetic energy distributions of metal-cationised molecules are broad in comparison with those of the parent ions, and of the smaller polystyrene fingerprint ions. In addition, the velocity distributions of the parent ions and of the metal-cationised molecules are similar. Parent ions of aromatic molecules are, on average, more energetic than those of aliphatic molecules. In the case of metal-cationised molecules, the three hypotheses of emission of a preformed complex, recombination in the selvedge and metastable decay of larger aggregates are critically reviewed in comparison with the experimental data. The recombination hypothesis cannot account for the whole set of observations. On the other hand, the very different evolutions of the parent ions and of the metal-cationised molecules in the degradation experiments cannot be explained solely in the frame of metastable decay reactions, although the kinetic energy measurements show that a significant fraction of the parent-like ions are produced in the vacuum. The augmentation of the secondary ion kinetic energy with increasing molecule size for triacontane monomers and dimers, and for silver-cationised polystyrene oligomers, is in disagreement with the sputtering by a single cascade atom, too. Finally, the discussion outlines the conditions that must be satisfied to model the experimental observations and proposes a view of the sputtering of these large molecular cations based on multiple collision processes and possible subsequent dissociation in the vacuum.

Delcorte, A.; Bertrand, P.

1998-09-01

360

Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue  

DOEpatents

In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about 249.degree. F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

Sharp, David W. (Seabrook, TX)

1980-01-01

361

Submicro and Nano Structured Porous Materials for the Production of High-Intensity Exotic Radioactive Ion Beams  

E-print Network

ISOLDE, the CERN Isotope Separator On-line DEvice is a unique source of low energy beams of radioactive isotopes - atomic nuclei that have too many or too few neutrons to be stable. The facility is like a small ‘chemical factory’, giving the possibility of changing one element to another, by selecting the atomic mass of the required isotope beam in the mass separator, rather as the ‘alchemists’ once imagined. It produces a total of more than 1000 different isotopes from helium to radium, with half-lives down to milliseconds, by impinging a 1.4 GeV proton beam from the Proton Synchrotron Booster (PSB) onto special targets, yielding a wide variety of atomic fragments. Different components then extract the nuclei and separate them according to mass. The post-accelerator REX (Radioactive beam EXperiment) at ISOLDE accelerates the radioactive beams up to 3 MeV/u for many experiments. A wide international user radioactive ion beam (RIB) community investigates fundamental aspects of nuclear physics, particle...

Fernandes, Sandrina; Stora, Thierry

2010-01-01

362

Spectropolarimetric titrimetry of metal ions and optically active chelating agents  

E-print Network

Black T. of G. F. Smith Co. analytical grade hydrated indium perchlorate in deionized water and diluting to 250 ml. The solution was standardized by a procedure from Welcher. An aliquot was titrated with standard EDTA at a pH of 2. 40 using PAN... Metal Metal Second Total First Second Total Metal Metal Metal Metal Metal Indium and Lanthanum Zirconiujll aIld Thorium 0. 753 0. 721 1. 474 0. 743 0. 707 1. 450 -1. 30 -1. 98 -1. 69 0. 709 0. 928 1. 637 0. 647 1. 145 1. 792 -8. 8 +23. 4 +9. 5...

Caldwell, Donald Lee

2012-06-07

363

Visualizing metal ions in cells: an overview of analytical techniques, approaches, and probes  

PubMed Central

Quantifying the amount and defining the location of metal ions in cells and organisms are critical steps in understanding metal homeostasis and how dyshomeostasis causes or is a consequence of disease. A number of recent advances have been made in the development and application of analytical methods to visualize metal ions in biological specimens. Here, we briefly summarize these advances before focusing in more depth on probes for examining transition metals in living cells with high spatial and temporal resolution using fluorescence microscopy. PMID:22521452

Dean, Kevin M.; Qin, Yan; Palmer, Amy E.

2012-01-01

364

Biosorption of heavy metal ions to brown algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida  

SciTech Connect

A fundamental study of the application of brown algae to the aqueous-phase separation of toxic heavy metals was carried out. The biosorption characteristics of cadmium and lead ions were determined with brown algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida. A metal binding model proposed by the authors was used for the description of metal binding data. The results showed that the biosorption of bivalent metal ions to brown algae was due to bivalent binding to carboxylic groups on alginic acid in brown algae.

Seki, Hideshi; Suzuki, Akira [Hokkaido Univ., Hakodate (Japan)] [Hokkaido Univ., Hakodate (Japan)

1998-10-01

365

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

PubMed

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

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

2013-02-14

366

Formation of NbAl 3 by Nb ion implantation using metal vapor vacuum arc ion source  

NASA Astrophysics Data System (ADS)

High aluminum content intermetallic compound NbAl 3 was formed by Nb ion implantation into Al films with a current density of 108 ?A cm -2 using a metal vapor vacuum arc (MEVVA) ion source. When the Nb ion dose was of 3 × 10 17 ions cm -2, NbAl 3 phase was formed. With increasing the ion dose, the crystallinity of NbAl 3 phase was gradually improved. The NbAl 3 layer with a thickness of about 1900 Å was obtained on the Al surface implanted by Nb ions up to a dose of 8 × 10 17 cm -2. The microhardness of the Nb implanted Al films was significantly increased by the NbAl 3 phase.

Miao, W.; Tao, K.; Liu, B. X.; Li, B.

2000-02-01

367

Adsorptions of some heavy metal ions in aqueous solutions by acrylamide/maleic acid hydrogels  

SciTech Connect

In this study, acrylamide-maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by {gamma}-radiation. They have been used for adsorption of some heavy metal ions such as uranium, iron, and copper. For the hydrogel containing 40 mg of maleic acid and irradiated at 3.73 kGy, maximum and minimum swellings in the aqueous solutions of the heavy metal ions have been observed with water (1480%) and the aqueous solution of iron(III) nitrate (410%), respectively. Diffusions of water and heavy metal ions onto hydrogels have been found to be of the non-Fickian type of diffusion. In experiments of uranyl ions adsorption, Type II adsorption has been found. One gram of AAa/MA hydrogels sorbed 14-86 mg uranyl ions from solutions of uranyl acetate, 14-90 mg uranyl ions from solutions of uranyl nitrate, 16-39 mg iron ions from solutions of iron(IV) nitrate, and 28-81 mg copper ions from solutions of copper acetate, while acrylamide hydrogel did not sorb any heavy metals ions.

Saraydin, D.; Karadag, E. [Cumhuriyet Univ., Sivas (Turkey); Gueven, O. [Hacettepe Univ., Ankara (Turkey)

1995-10-01

368

Plastic flow produced by single ion impacts on metals.  

SciTech Connect

Single ion impacts have been observed using in situ transmission electron microscopy and video recording with a time resolution of 33 milliseconds. Gold was irradiated at 50 K and room temperature. Single ion impacts produce holes, modify existing holes, and extrude material into the initial specimen hole and holes formed by other ion impacts. The same behavior is observed at both temperatures. At both temperatures, ion impacts result in craters and ejected material. Ion impacts produce more small craters than large ones for all ion masses, while heavier mass ions produce more and larger craters than lighter mass ions. This comparison is affected by the ion energy. As the energy of an ion is increased, the probability for deposition near the surface decreases and fewer craters are formed. For a given ion mass, crater production depends on the probability for displacement cascade production in the near surface region. Crater and holes are stable at room temperature, however, ion impacts near an existing crater may cause flow of material into the crater either reshaping or annihilating it. Holes and craters result from the explosive outflow of material from the molten zone of near-surface cascades. The outflow may take the form of molten material, a solid lid or an ejected particle. The surface is a major perturbation on displacement cascades resulting from ion impacts.

Birtcher, R. C.

1998-10-30

369

MICROSTRUCTURE EVOLUTION OF NANOCRYSTALLINE METALLIC THIN-FILMS UNDER ION-BEAM IRRADIATION.  

E-print Network

??The microstructural evolution of nanocrystalline metallic thin-films under ion irradiation, especially grain growth and second-phase precipitation, was studied with detailed in situ experiments, and a… (more)

Kaoumi, Djamel

2007-01-01

370

Colorimetric chemosensor for multi-signaling detection of metal ions using pyrrole based Schiff bases  

NASA Astrophysics Data System (ADS)

Pyrrole based Schiff bases act as a highly sensitive probe for metal ions in aqueous medium. Both receptors R1 and R2 are sensitive towards Fe3+, Cu2+, Hg2+ and Cr3+ among the other metal ions. The sensing ability of the receptors are investigated via colorimetric, optical and emission spectroscopic studies. The binding stoichiometries of R1 and R2 with metal ions have been determined as 2:1 by using Job's plot. The colorimetric receptors exhibited high sensitivity with a low detection limit of ?M levels. In the presence of metal ions both receptors shows fluorescence quenching. This might be due to the photo induced electron transfer mechanism. The quenching constant was further determined using Stern-Volmer plot.

Udhayakumari, Duraisamy; Velmathi, Sivan

2014-03-01

371

The study of 8-Hydroxyquinoline-2-Carboxyllic acid and its metal ion complexing properties.  

E-print Network

??The metal ion coordinating properties of the ligand HQC (8-hydroxyquinoline-2- carboxylic acid) were studied by UV-visible spectroscopy and X-ray crystallography. The protonation constants of HQC… (more)

McDonald, F. Crisp Jr.

2009-01-01

372

Effects of Alkaline Earth Metal Ion Complexation on Amino Acid Zwitterion Stability: Results from Infrared Action  

E-print Network

for Plasma Physics "Rijnhuizen", Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands Received December 21 but the smallest alkaline earth metal ion, University of California, Berkeley. FOM Institute for Plasma Physics

Cohen, Ronald C.

373

Characterization of phosphorus liquid-metal ion source as a dopant source in focused ion beam systems  

Microsoft Academic Search

Characteristics of a phosphorus liquid-metal ion source (LMIS) for use in focused ion beam systems was investigated because of its potential as an n-type dopant for integrated circuit device fabrication. A continuous lifetime of more than 33 h was recorded as a part of the source stability measurement. Short-term stability measurements indicated a very stable beam emission during its operation.

R. H. Higuchi-Rusli; J. C. Corelli

1988-01-01

374

Analyses of impact of metal ion contamination on carp ( Cyprinus carpio L.) gill cell suspensions  

Microsoft Academic Search

The decline in fish population because of water contamination is problem. As a result of direct exposure in water, it has\\u000a been readily accepted that the gills are the main site of water contamination and toxicity (e.g., metal ions). In the present\\u000a study, we investigated metal ion contamination on the functional capacity of carp gill cells with antioxidant interactions\\u000a in

M. Arabi

2004-01-01

375

Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters  

E-print Network

Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

Dash, Monika

2013-01-01

376

Importance of diffuse metal ion binding to RNA.  

PubMed

RNAs are highly charged polyanionic molecules. RNA structure and function are strongly correlated with the ionic condition of the solution. The primary focus of this article is on the role of diffusive ions in RNA folding. Due to the long-range nature of electrostatic interactions, the diffuse ions can contribute significantly to RNA structural stability and folding kinetics. We present an overview of the experimental findings as well as the theoretical developments on the diffuse ion effects in RNA folding. This review places heavy emphasis on the effect of magnesium ions. Magnesium ions play a highly efficient role in stabilizing RNA tertiary structures and promoting tertiary structural folding. The highly efficient role goes beyond the mean-field effect such as the ionic strength. In addition to the effects of specific ion binding and ion dehydration, ion-ion correlation for the diffuse ions can contribute to the efficient role of the multivalent ions such as the magnesium ions in RNA folding. PMID:22010269

Tan, Zhi-Jie; Chen, Shi-Jie

2011-01-01

377

New Catalytic DNA Biosensors for Radionuclides and Metal ions  

SciTech Connect

In vitro selection for DNAzymes that are catalytically active with UO22+ ions as the metal cofactor has been completed. The 10th generation pool of DNA was cloned and sequenced. A total of 84 clones were sequenced and placed into families based on sequence alignments. Selected members of each family were 5-labeled with 32P and amplified using PCR. Activity assays were conducted using the isotopically labeled DNAzymes in order to determine which sequences were the most active. The secondary structures of the two most active sequences, called Clone 13 and Clone 39, were determined using the computer program Mfold. A cleavage rate of approximately 1 min-1 in the presence of 10 uM UO22+ was observed for both clones. Clone 39 was determined to be the best candidate for truncation to create a trans-cleaving DNAzyme, based on its secondary structure. An enzyme strand, called 39E, and a substrate strand, called 39DS, were designed by truncating the cis-cleaving DNAzyme. An alternative enzyme strand, called 39Ec, was also assayed with the 39DS substrate. This strand was designed so that the two binding arms were perfectly complimentary, unlike 39E, which formed three mismatched base pairs with 39DS. Both 39E and 39Ec were found to be active, with a rate of approximately 1 min-1 in the presence of 10 uM UO22+. A preliminary UO22+ binding curve was obtained for the 39Ec/39DS trans-cleaving system. The enzyme is active with UO22+ concentrations as low as 1 nM. Based on the preliminary binding curve data, the apparent UO22+ binding constant is approximately 330 nM, and kmax is approximately 1 min-1.

Lu, Yi

2005-06-01

378

Metal ion and ligand binding of integrin ?5?1.  

PubMed

Integrin ?5?1 binds to an Arg-Gly-Asp (RGD) motif in its ligand fibronectin. We report high-resolution crystal structures of a four-domain ?5?1 headpiece fragment, alone or with RGD peptides soaked into crystals, and RGD peptide affinity measurements. The headpiece crystallizes in a closed conformation essentially identical to that seen previously for ?5?1 complexed with a Fab that allosterically inhibits ligand binding by stabilizing the closed conformation. Soaking experiments show that binding of cyclic RGD peptide with 20-fold higher affinity than a linear RGD peptide induces conformational change in the ?1-subunit ?I domain to a state that is intermediate between closed (low affinity) and open (high affinity). In contrast, binding of a linear RGD peptide induces no shape shifting. However, linear peptide binding induces shape shifting when Ca(2+) is depleted during soaking. Ca(2+) bound to the adjacent to metal ion-dependent adhesion site (ADMIDAS), at the locus of shape shifting, moves and decreases in occupancy, correlating with an increase in affinity for RGD measured when Ca(2+) is depleted. The results directly demonstrate that Ca(2+) binding to the ADMIDAS stabilizes integrins in the low-affinity, closed conformation. Comparisons in affinity between four-domain and six-domain headpiece constructs suggest that flexible integrin leg domains contribute to conformational equilibria. High-resolution views of the hybrid domain interface with the plexin-semaphorin-integrin (PSI) domain in different orientations show a ball-and-socket joint with a hybrid domain Arg side chain that rocks in a PSI domain socket lined with carbonyl oxygens. PMID:25475857

Xia, Wei; Springer, Timothy A

2014-12-16

379

Biosorption of heavy metal ions from aqueous solution by red macroalgae.  

PubMed

Biosorption is an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine algae has been reported to have high biosorption capacities for a number of heavy metal ions. In this study, four species of red seaweeds Corallina mediterranea, Galaxaura oblongata, Jania rubens and Pterocladia capillacea were examined to remove Co(II), Cd(II), Cr(III) and Pb(II) ions from aqueous solution. The experimental parameters that affect the biosorption process such as pH, contact time and biomass dosage were studied. The maximum biosorption capacity of metal ions was 105.2mg/g at biomass dosage 10 g/L, pH 5 and contact time 60 min. The biosorption efficiency of algal biomass for the removal of heavy metal ions from industrial wastewater was evaluated for two successive cycles. Galaxaura oblongata biomass was relatively more efficient to remove metal ions with mean biosorption efficiency of 84%. This study demonstrated that these seaweeds constitute a promising, efficient, cheap and biodegradable sorbent biomaterial for lowering the heavy metal pollution in the environment. PMID:21798665

Ibrahim, Wael M

2011-09-15

380

Coordination environment of the active-site metal ion of liver alcohol dehydrogenase.  

PubMed Central

The coordination environment of the catalytically active metal ion of horse liver alcohol dehydrogenase (alcohol:NAD+ oxidoreductase, EC 1.1.1.1) has been investigated by electron paramagnetic resonance (EPR) methods with use of the active-site-specific Co2+-reconstituted enzyme. The EPR absorption spectrum of the metal-substituted enzyme is characteristic of a rhombically distorted environment. The spectrum of the enzyme--NAD+ complex shows approximate axial symmetry of the metal ion site, indicating that binding of the coenzyme induces a structural alteration in the active-site region. This environment is not significantly altered further by binding of the competitive inhibitor pyrazole. To assign the coordination number of the active-site metal ion, the zero-field splitting was determined on the basis of the temperature dependence of the spin--lattice relaxation of the Co2+ ion. The zero-field splitting energies are approximately 9 cm-1 for the free Co2+-reconstituted enzyme and approximately 46 and approximately 47 cm-1 for the enzyme--NAD+ and enzyme--NAD+--pyrazole complex, respectively. On the basis of studies of structurally defined small molecule complexes, these values are compatible with a tetracoordinate metal ion in the active site of the free enzyme but a pentacoordinate metal ion in the binary enzyme--NAD+ complex and in the ternary enzyme--NAD+--inhibitor complex and, therefore, presumably also in the catalytically active ternary enzyme--NAD+--alcohol complex formed in the course of alcohol oxidation. PMID:6273859

Makinen, M W; Yim, M B

1981-01-01

381

Application of immobilized metal ion chelate complexes as pseudocation exchange adsorbents for protein separation.  

PubMed

The interactions of horse muscle myoglobin (MYO), tuna heart cytochrome c (CYT), and hen egg white lysozyme (LYS) with three different immobilized metal ion affinity (IMAC) adsorbents involving the chelated complexes of the hard Lewis metal ions Al3+, Ca2+, Fe3+, and Yb3+ and the borderline Lewis metal ion Cu2+ have been investigated in the presence of low- and high-ionic strength buffers and at two different pH values. In contrast to the selectivity behavior noted with buffers of high ionic strength, with low-ionic strength buffers, these three proteins interact with the hard metal ion IMAC adsorbents in a manner more characteristic of cation exchange behavior, although in contrast to the cation exchange chromatography of these proteins, as the pH value of the elution buffer was increased, the retention also increased. The selectivity differences observed under these conditions appear to be due to the formation of hydrolytic complexes of these immobilized metal ion chelate systems involving a change in the coordination geometry of the im-M(n+)-chelate at higher pH values. The experimental observations have been evaluated in terms of the effective charge on the immobilized metal ion chelate complex and the charge characteristics of the specific proteins. PMID:8555175

Zachariou, M; Hearn, M T

1996-01-01

382

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

NASA Astrophysics Data System (ADS)

This dissertation focuses on the study of interactions between transition metal ions (Cu(II), Zn(II), Pd(II), Pt(II)) and peptides (bradykinins and angiotensins). Chapter I provides an overview on the fundamental issues related to and techniques used for studying transition metal ion -peptide/protein complexes. It also reviews different mass spectroscopic techniques used for metal ion-peptide studies. Chapter II delineates the principle of ^{252 }Cf-PDMS instrumentation and the sample preparation methods utilized for this dissertation research. In order to study metal ion-peptide complexes with PDMS, it is essential to define the relationship between complex structures identified from PD mass spectra and complexes formed in solution phase. Chapter III includes the studies of the effects of solution conditions on the detection of metal ion-peptide complexes in PDMS. Solution pH is the most important factor for determining the formation of a complex. Reaction time, reactant concentration, and reaction temperature all display distinct influences on PDMS results. It demonstrates that the PDMS results are closely correlated with the complexes pre-formed in aqueous solution. Chapter IV provides ample spectroscopic data on peptides and their metal ion complexes. The metal ion -containing molecular ions observed provide information on numbers of metal ion-binding sites in a peptide and metal ion-affinity of the peptide. By analyzing fragmentation patterns, amino acid residues and functional groups involved in metal ion binding in a peptide can be identified.

Hu, Zhaohong

383

Self-propelled droplets for extracting rare-earth metal ions.  

PubMed

We have developed self-propelled droplets having the abilities to detect a chemical gradient, to move toward a higher concentration of a specific metal ion (particularly the dysprosium ion), and to extract it. Such abilities rely on the high surface activity of di(2-ethylhexyl) phosphoric acid (DEHPA) in response to pH and the affinity of DEHPA for the dysprosium ion. We used two external stimuli as chemical signals to control droplet motion: a pH signal to induce motility and metal ions to induce directional sensing. The oil droplets loaded with DEHPA spontaneously move around beyond the threshold of pH even in a homogeneous pH field. In the presence of a gel block containing metal ions, the droplets show directional sensing and their motility is biased toward higher concentrations. The metal ions investigated can be arranged in decreasing order of directional sensing as Dy(3+)? Nd(3+) > Y(3+) > Gd(3+). Furthermore, the analysis of components by using an atomic absorption spectrophotometer reveals that the metal ions can be extracted from the environmental media to the interiors of the droplets. This system may offer alternative self-propelled nano/microscale machines to bubble thrust engines powered by asymmetrical catalysts. PMID:25029997

Ban, Takahiko; Tani, Kentaro; Nakata, Hiroki; Okano, Yasunori

2014-09-01

384

First results of Trojan horse method using radioactive ion beams: {sup 18}F(p,?) at astrophysical energies  

SciTech Connect

The abundance of {sup 18}F in Nova explosions is considered to be an important piece of information for the understanding of this astrophysical phenomenon. It is then necessary to study the nuclear processess that both produce and destroy this isotope in Novae. Among these latter reactions, the {sup 18}F(p,?){sup 15}O is one of the most important {sup 18}F destruction channels. Here we report on an experiment performed using the CRIB apparatus of the Center for Nuclear Study of the University of Tokyo. This was the first experiment that used the Trojan Horse method applied to a Radioactive Ion Beam induced reaction.

Cherubini, S.; Spitaleri, C.; Puglia, S.; Rapisarda, G.; Romano, S. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania, Italy and INFN - Laboratori Nazionali del Sud, Catania (Italy); Gulino, M. [Università KORE, Enna, Italy and INFN - Laboratori Nazionali del Sud, Catania (Italy); La Cognata, M. [INFN - Laboratori Nazionali del Sud, Catania (Italy); Lamia, L. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Kubono, S.; Wakabayashi, Y. [Center for Nuclear Study, University of Tokyo, Tokyo, Japan and present address RIKEN Nishina Center, Wako, Saitama (Japan); Yamaguchi, H.; Hayakawa, S.; Kurihara, Y. [Center for Nuclear Study, University of Tokyo, Tokyo (Japan); Binh, D. [Center for Nuclear Study, University of Tokyo, Tokyo, Japan and present address Institute of Physics and Electronics, Vietnam Academy of Science and Technology, Hanoi (Viet Nam); Bishop, S. [RIKEN Nishina Center, Wako, Saitama, Japan and present address Physik Department E12, Technische Universität München, Garching (Germany); Coc, A. [Centre de Spectrométrie Nucléaire et de Spectrométrie de masse, IN2P3, Orsay (France); De Séréville, N.; Hammache, F. [Institut de Physique Nucléaire, IN2P3, Orsay (France)

2014-05-02

385

Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma  

SciTech Connect

This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

Hsieh, Tung-Yuan; Kawamori, Eiichirou [Institute of Space, Astrophysical and Plasma Sciences, National Cheng Kung University, Taiwan (China); Nishida, Yasushi [Plasma and Space Science Center, National Cheng Kung University, Taiwan (China)

2013-02-15

386

The fabrication of metal silicide nanodot arrays using localized ion implantation.  

PubMed

We propose a process for fabricating nanodot arrays with a pitch size of less than 25 nm. The process consists of localized ion implantation in a metal thin film on a Si wafer using a focused ion beam (FIB), followed by chemical etching. This process utilizes the etching resistivity changes of the ion beam irradiated region that result from metal silicide formation by ion implantation. To control the nanodot diameter, a threshold ion dose model is proposed using the Gaussian distribution of the ion beam intensities. The process is verified by fabricating nanodots with various diameters. The mechanism of etching resistivity is investigated via x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). PMID:21063049

Han, Jin; Kim, Tae-Gon; Min, Byung-Kwon; Lee, Sang Jo

2010-12-01

387

Identification of Metals (Heavy and Radioactive) in Drinking Water by an Indirect Analysis Method Based on Scale Tests  

PubMed Central

The analysis of water quality, regarding the content of metals, especially heavy and radioactive ones, has been carried out in an indirect way, by testing scale formed in a hot-water heater, using water from the water-supply network of the city of Belgrade – the district of New Belgrade. The determination of the composition and the structure of the scale has resulted in its complete identification, and its crystallochemical formula has been defined. It has unequivocally been established that the obtained results are within the tolerance boundary with the results acquired by a conventional analysis of water, when it is a matter of very low concentrations. The presence of radioactive elements of uranium and strontium in a scale sample has been found and the way of their penetrating its composition and structure has been explained. Applying the fractional extraction method, uranium has been established to be of an anthropogenic origin.

Rajkovic, Miloš B.; Lacnjevac, Caslav M.; Ralevic, Nebojsa R.; Stojanovi?, Mirjana D.; Toskovi?, Dragan V.; Pantelic, Gordana K.; Ristic, Nikola M.; Jovanic, Sasa

2008-01-01

388

Oscillatory concentration pulses of some divalent metal ions induced by a redox oscillator  

E-print Network

by a pH oscillator backward and forward, we now couple a redox core oscillating reaction to two reactions between the input reagents of the core oscillator and the target non- redox ion. This modifiedOscillatory concentration pulses of some divalent metal ions induced by a redox oscillator Viktor

Epstein, Irving R.

389

Titanium alloy mini-implants for orthodontic anchorage: Immediate loading and metal ion release q  

E-print Network

Titanium alloy mini-implants for orthodontic anchorage: Immediate loading and metal ion release q 2006 Abstract Removable osseointegrated titanium mini-implants were successfully used as anchorage ion release during the healing pro- cess. Titanium alloy mini-implants were inserted in the tibiae

Meyers, Marc A.

390

Water uptake and migration effects of electroactive ion-exchange polymer metal composite (IPMC) actuator  

Microsoft Academic Search

The low actuating voltage and quick bending responses of ion-exchange polymer metal composite (IPMC) are considered very attractive for the construction of various types of actuators and sensors. The principle of IPMC actuation under electric field has been believed to be the ion cluster flux and electro-osmotic drag of water from the anode to cathode direction through the hydrophilic channels

Jun Ho Lee; Jong Hoon Lee; Jae-Do Nam; Hyoukryeol Choi; Kwangmok Jung; Jae Wook Jeon; Young Kwan Lee; Kwang Jin Kim; Yongsug Tak

2005-01-01

391

Property enchancement of polyimide films by way of the incorporation of lanthanide metal ions  

NASA Technical Reports Server (NTRS)

Lanthanide metal ions were incorporated into the polyimide derived from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 1,3-bis(aminophenoxy) benzene (APB) in an attempt to produce molecular level metal-polymer composites. The lanthanide series of metal ions (including aluminum, scandium, and yttrium) provide discrete and stable metal ions in the 3+ oxidation state. Throughout the series there is a uniform variation in ionic size ranging from 50 pm for aluminum to a maximum of 103.4 pm for cerium and gradually decreasing again to 84.8 pm for lutetium. The high charge-to-size ratio for these ions as well as the ability to obtain large coordination numbers makes them excellent candidates for interacting with the polymer substructure. The distinct lack of solubility of simple lanthanide salts such as the acetates and halides has made it difficult to obtain metal ions distributed in the polymer framework as discrete ions or metal complexes rather than microcomposites of metal clusters. (Lanthanum nitrates are quite soluble, but the presence of the strongly oxidizing nitrate ion leads to serious degradation of the polymer upon thermal curing. This work was successful at extending the range of soluble metals salts by using chelating agents derived from the beta-diketones dipivaloylmethane, dibenzoylmethane, trifluoroacetylacetone, and hexafluoroacetylacetone. Metal acetates which are insoluble in dimethylacetamide dissolve readily in the presence of the diketones. Addition of the polyimide yields a homogeneous resin which is then cast into a clear film. Upon curing clear films were obtained with the dibenzoylmethane and trifluoroacetylacetone ligands. The dipavaloylmethane precipitates the metal during the film casting process, and hexafluoroacetylacetone gives cured films which are deformed and brittle. These clear films are being evaluated for the effect of the metal ions on the coefficient of thermal expansion, resistance to atomic oxygen, and on selective gas permeability. Much more commonly than above, polyimide films are prepared by casting the film as the poly(amic acid) precursor which is then converted to the imidized form during the thermal cure cycle. Very limited success was achieved in the past in adding lanthanide metal ions to the amide precursors because of gellation and lack of solubility. With the use of the diketone ligands cited above, the solubility and gellation problems were overcome. However, the films after curing were clear but unacceptably brittle. Attempts to overcome this cure embrittlement problem are in progress.

Thompson, David W.

1993-01-01

392

Metal ions affecting the pulmonary and cardiovascular systems.  

PubMed

Some metals, such as copper and manganese, are essential to life and play irreplaceable roles in, e.g., the functioning of important enzyme systems. Other metals are xenobiotics, i.e., they have no useful role in human physiology and, even worse, as in the case of lead, may be toxic even at trace levels of exposure. Even those metals that are essential, however, have the potential to turn harmful at very high levels of exposure, a reflection of a very basic tenet of toxicology--"the dose makes the poison." Toxic metal exposure may lead to serious risks to human health. As a result of the extensive use of toxic metals and their compounds in industry and consumer products, these agents have been widely disseminated in the environment. Because metals are not biodegradable, they can persist in the environment and produce a variety of adverse effects. Exposure to metals can lead to damage in a variety of organ systems and, in some cases, metals also have the potential to be carcinogenic. Even though the importance of metals as environmental health hazards is now widely appreciated, the specific mechanisms by which metals produce their adverse effects have yet to be fully elucidated. The unifying factor in determining toxicity and carcinogenicity for most metals is the generation of reactive oxygen and nitrogen species. Metal-mediated formation of free radicals causes various modifications to nucleic acids, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Whilst copper, chromium, and cobalt undergo redox-cycling reactions, for metals such as cadmium and nickel the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. This chapter attempts to show that the toxic effects of different metallic compounds may be manifested in the pulmonary and cardiovascular systems. The knowledge of health effects due to metal exposure is necessary for practising physicians, and should be assessed by inquiring about present and past occupational history and environmental exposure. PMID:21473377

Corradi, Massimo; Mutti, Antonio

2011-01-01

393

Improved ion extraction from an electron cyclotron resonance ion source by a metal-dielectric-extraction electrode  

NASA Astrophysics Data System (ADS)

The goal of the experiment was to study the influence and the physics of the boundary region (between the plasma and the extraction potential) with direct impact on the source ion-beam output. A specially processed high-emissive metal-dielectric structure was installed on the extraction electrode of the Frankfurt 14GHz electron cyclotron resonance ion source (ECRIS), forming a so-called metal-dielectric- (MD) extraction electrode. The emissive layer of the disk faced the plasma; its inner hole was about the size of the normal extraction hole of the ECRIS. The output of the ECRIS in the presence of the MD electrode was compared with the outputs for the standard configuration (overall stainless-steel plasma chamber) and with the same plasma chamber with the radial wall covered by a highly electron emissive MD liner that raise the plasma electron density and temperature. The charge state distributions of the argon ions extracted from the source show an important increase of the ion beam for the high charge states as compared to the standard situation whereas the low charge states are less reduced than in the case of the presence of a MD liner. Due to the special position of the dielectric layer, the MD electrode introduces a new effect, which is connected to its property of becoming a positively charged surface under electron and ion bombardment. The MD electrode creates a quasiconfinement of the peripheral ions in the extraction, those ions that are normally lost to a conducting extraction electrode.

Schachter, L.; Dobrescu, S.; Stiebing, K. E.

2006-03-01

394

Improved ion extraction from an electron cyclotron resonance ion source by a metal-dielectric-extraction electrode  

SciTech Connect

The goal of the experiment was to study the influence and the physics of the boundary region (between the plasma and the extraction potential) with direct impact on the source ion-beam output. A specially processed high-emissive metal-dielectric structure was installed on the extraction electrode of the Frankfurt 14 GHz electron cyclotron resonance ion source (ECRIS), forming a so-called metal-dielectric- (MD) extraction electrode. The emissive layer of the disk faced the plasma; its inner hole was about the size of the normal extraction hole of the ECRIS. The output of the ECRIS in the presence of the MD electrode was compared with the outputs for the standard configuration (overall stainless-steel plasma chamber) and with the same plasma chamber with the radial wall covered by a highly electron emissive MD liner that raise the plasma electron density and temperature. The charge state distributions of the argon ions extracted from the source show an important increase of the ion beam for the high charge states as compared to the standard situation whereas the low charge states are less reduced than in the case of the presence of a MD liner. Due to the special position of the dielectric layer, the MD electrode introduces a new effect, which is connected to its property of becoming a positively charged surface under electron and ion bombardment. The MD electrode creates a quasiconfinement of the peripheral ions in the extraction, those ions that are normally lost to a conducting extraction electrode.

Schachter, L.; Dobrescu, S.; Stiebing, K.E. [National Institute for Physics and Nuclear Engineering (IFIN-HH), P.O. Box MG-6, Bucharest (Romania); Institut fuer Kernphysik der Johann Wolfgang Goethe-Universitaet (IKF), Max-von-Laue-Strasse 1, D-60438 Frankfurt (Germany)

2006-03-15

395

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

SciTech Connect

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

Magee, E. W., E-mail: magee1@llnl.gov; Beiersdorfer, P.; Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, 96049 Bamberg (Germany)

2014-11-15

396

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

397

A self-sensing ion conducting polymer metal composite (IPMC) actuator  

Microsoft Academic Search

This paper describes a novel self-sensing ion-conductive polymer metal composite (IPMC) actuator. The actuator gives feedback of its own position and thereby can also be used as a position sensor. Unlike the IPMC sensors reported so far, the working principle of this actuator is based on the observation that the resistance of the IPMC metal surface electrode is correlated to

Andres Punning; Maarja Kruusmaa; Alvo Aabloo

2007-01-01

398

A study on an ion polymer metal composite actuator as a self-sensing system  

Microsoft Academic Search

An ion polymer metal composite (IPMC) is an Electro-Active Polymer (EAP) that bends in response to a small electrical field as a result of mobility of cations in the polymer network and vice versa. A typical IPMC sheet is constructed with a thin ionic polymer membrane and two metal electrode layers outside. This paper proposes an idea to estimate the

K. K. Ahn; D. N. C. Nam; D. Q. Truong; J. I. Yoon; T. Q. Thanh

2009-01-01

399

Poultry litter-based activated carbon for removing heavy metal ions in water.  

PubMed

Utilization of poultry litter as a precursor material to manufacture activated carbon for treating heavy metal-contaminated water is a value-added strategy for recycling the organic waste. Batch adsorption experiments were conducted to investigate kinetics, isotherms, and capacity of poultry litter-based activated carbon for removing heavy metal ions in water. It was revealed that poultry litter-based activated carbon possessed significantly higher adsorption affinity and capacity for heavy metals than commercial activated carbons derived from bituminous coal and coconut shell. Adsorption of metal ions onto poultry litter-based carbon was rapid and followed Sigmoidal Chapman patterns as a function of contact time. Adsorption isotherms could be described by different models such as Langmuir and Freundlich equations, depending on the metal species and the coexistence of other metal ions. Potentially 404 mmol of Cu2+, 945 mmol of Pb2+, 236 mmol of Zn2+, and 250-300 mmol of Cd2+ would be adsorbed per kg of poultry litter-derived activated carbon. Releases of nutrients and metal ions from litter-derived carbon did not pose secondary water contamination risks. The study suggests that poultry litter can be utilized as a precursor material for economically manufacturing granular activated carbon that is to be used in wastewater treatment for removing heavy metals. PMID:19783133

Guo, Mingxin; Qiu, Guannan; Song, Weiping

2010-02-01

400

Single-metal-ion-based molecular building blocks (MBBs) approach to the design and synthesis of metal organic assemblies  

NASA Astrophysics Data System (ADS)

The single-metal-ion-based molecular building blocks (MBBs) approach for the construction of metal-organic assemblies, in which hetero-coordinated single metal ions are rendered rigid and directional via nitrogen-oxygen chelation with judiciously selected ligands, has been implemented. Single-metal-ion-based MBBs of the general formula MN x(CO 2) y constitute the building units of metal-organic frameworks (MOFs) and metal-organic polyhedra (MOPs) presented herein. The octahedral MBB, MN 2(CO 2) 4, can occur as two structural isomers depending on the positioning of nitrogen atoms. The MN 2(CO 2) 4 MBBs contain two rings of heterochelation, and depending on the position of the oxygen atoms involved in heterochelation it is possible to generate three different building units (BUs) from the cis-MN 2(CO 2) 4 MBB and two BUs from the trans-MN 2(CO 2) 4 MBB. Assembly of the different BUs derived from the cis-MN 2(CO 2) 4 MBB, through a bifunctional ligand such as 2,5-pyridinedicarboxylic acid, permits the construction of diverse assemblies, such as a metal-organic 2D Kagomé lattice, a discrete octahedron, and a 3D diamondoid-like network. The fac-MN 3(CO 2) 3 MBB mediates a BU with the appropriate geometry to facilitate the formation of a metal-organic cube, and the BU resulting from the mer-MN 3(CO 2) 3 MBB is T-shaped. Tetrahedral building units (TBUs) can be derived either from MN 4(CO 2) 2 or MN 4(CO 2) 4 MBBs, from which zeolite-like MOFs have been constructed. Foremost, rationalization and systemization of such findings offer great potential toward the pursuit of the logical synthesis of functional metal-organic assemblies.

Brant, Jacilynn A.; Liu, Yunling; Sava, Dorina F.; Beauchamp, Derek; Eddaoudi, Mohamed

2006-08-01

401

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

Microsoft Academic Search

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

Masamichi Tsuji; Sridhar Komarneni

1993-01-01

402

18-Electron rule inspired Zintl-like ions composed of all transition metals.  

PubMed

Zintl phase compounds constitute a unique class of compounds composed of metal cations and covalently bonded multiply charged cluster anions. Potential applications of these materials in solution chemistry and thermoelectric materials have given rise to renewed interest in the search for new Zintl ions. Up to now these ions have been mostly composed of group 13, 14, and 15 post-transition metal elements and no Zintl ions composed of all transition metal elements are known. Using gradient corrected density functional theory we show that the 18-electron rule can be applied to design a new class of Zintl-like ions composed of all transition metal atoms. We demonstrate this possibility by using Ti@Au12(2-) and Ni@Au6(2-) di-anions as examples of Zintl-like ions. Predictive capability of our approach is demonstrated by showing that FeH6(4-) in an already synthesized complex metal hydride, Mg2FeH6, is a Zintl-like ion, satisfying the 18-electron rule. We also show that novel Zintl phase compounds can be formed by using all transition metal Zintl-like ions as building blocks. For example, a two-dimensional periodic structure of Na2[Ti@Au12] is semiconducting and nonmagnetic while a one-dimensional periodic structure of Mg[Ti@Au12] is metallic and ferromagnetic. Our results open the door to the design and synthesis of a new class of Zintl-like ions and compounds with potential for applications. PMID:25139391

Zhou, Jian; Giri, Santanab; Jena, Purusottam

2014-10-01

403

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

E-print Network

to the ribozyme,oligonucleotide substrate (E,S) complex 20-fold and increases the binding of S to the E,GNH2 of a Metal Ion Interaction with the 2-Moiety of the Guanosine Nucleophile in the Tetrahymena Group I Ribozyme (GNH2) in the reaction catalyzed by the Tetrahymena group I ribozyme (E), and the Mn2+ concentration

Herschlag, Dan

404

Biodegradable radioactive implants for glaucoma filtering surgery produced by ion implantation  

NASA Astrophysics Data System (ADS)

A biodegradable, ?-emitting implant has been developed and successfully tested which prevents fresh intraocular pressure increase after glaucoma filtering surgery. Ion implantation has been used to load the polymeric implants with the ?-emitter 32P. The influence of ion implantation and gamma sterilisation on degradation and 32P-fixation behavior has been studied by ion beam and chemical analysis. Irradiation effects due to the applied ion fluence (10 15 ions/cm 2) and gamma dose (25 kGy) are found to be tolerable.

Assmann, W.; Schubert, M.; Held, A.; Pichler, A.; Chill, A.; Kiermaier, S.; Schlösser, K.; Busch, H.; Schenk, K.; Streufert, D.; Lanzl, I.

2007-04-01

405

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

Microsoft Academic Search

A fundamental study of the application of brown algae to the aqueous-phase separation of toxic heavy metals was carried out. The biosorption characteristics of cadmium and lead ions were determined with brown algae,Macrocystis pyrifera, Kjellmaniella crassiforia,andUndaria pinnatifida.A metal binding model proposed by the authors was used for the description of metal binding data. The results showed that the biosorption of

Hideshi Seki; Akira Suzuki

1998-01-01

406

Applications of Protein-Based Capacitive Biosensors for the Detection of Heavy-Metal Ions  

Microsoft Academic Search

Three different methods of using protein-based capacitive biosensors for the detection of heavy-metal ions are presented. The metal-binding proteins SmtA, S100A12, MerP and four modified MerPs were immobilised as the bio-recognition element on self-assembled monolayer-modified gold electrodes. Capacitance was measured using potential square step or electrical impedance spectroscopy. The protein-metal interaction generated changes in capacitance mainly due to a protein

Alessia Mortari; Nigel L. Brown; Carolyn Geczy; Hans G. L. Coster; Stella M. Valenzuela; Donald Martin; Elisabeth Csöregi

2006-01-01

407

Pyridinyl hydrazone derivatives of thiacalix[4]arene as selective extractants of transition metal ions  

Microsoft Academic Search

The recognition ability of pyridinyl hydrazone derivatives of cone- and 1,3-alternate tetrathiacalix[4]arenes towards transition and alkali metals has been investigated by picrate extraction method. The stoichiometry\\u000a of complexes and the extraction constants have been determined. It has been found that hydrazones do not extract alkali metal\\u000a ions but show an excellent affinity towards transition and heavy metal cations. The removal

Sergey N. PodyachevNadezda; Nadezda E. Burmakina; Victor V. Syakaev; Svetlana N. Sudakova; Wolf D. Habicher; Alexander I. Konovalov

408

Effects of CoCr metal wear debris generated from metal-on-metal hip implants and Co ions on human monocyte-like U937 cells.  

PubMed

Hip resurfacing with cobalt-chromium (CoCr) alloy was developed as a surgical alternative to total hip replacement. However, the biological effects of nanoparticles generated by wear at the metal-on-metal articulating surfaces has limited the success of such implants. The aim of this study was to investigate the effects of the combined exposure to CoCr nanoparticles and cobalt ions released from a resurfacing implant on monocytes (U937 cells) and whether these resulted in morphology changes, proliferation alterations, toxicity and cytokine release. The interaction between prior exposure to Co ions and the cellular response to nanoparticulate debris was determined to simulate the situation in patients with metal-on-metal implants receiving a second implant. Effects on U937 cells were mainly seen after 120h of treatment. Prior exposure to Co ions increased the toxic effects induced by the debris, and by Co ions themselves, suggesting the potential for interaction in vivo. Increased TNF-? secretion by resting cells exposed to nanoparticles could contribute to osteolysis processes in vivo, while increased IFN-? production by activated cells could represent cellular protection against tissue damage. Data suggest that interactions between Co ions and CoCr nanoparticles would occur in vivo, and could threaten the survival of a CoCr metal implant. PMID:25433333

Posada, Olga M; Tate, Rothwelle J; Grant, M Helen

2015-03-01

409

Refining technology for the recycling of stainless steel radioactive scrap metals, FY 94 bi-annual report  

SciTech Connect

The research addressed under this project is the recycling of metallic nuclear-related by-product materials under the direction of Westinghouse Idaho Nuclear Company (WINCO). The program addresses the recycling of radioactive scrap metals (RSM) for beneficial re-use within the DOE complex; in particular, this program addresses the recycling of stainless steel RSM. It is anticipated that various stainless steel components under WINCO control at the Idaho Falls Engineering Laboratory (INEL), such as fuel pool criticality barriers and fuel storage racks will begin to be recycled in FY94-95. The end product of this recycling effort is expected to be waste and overpack canisters for densified high level waste for the Idaho Waste Immobilization Facility and/or the Universal Canister System for dry (interim) storage of spent fuel. The specific components of this problem area that are presently being, or have been, addressed by CAAMSEC are: (1) the melting/remelting of stainless steel RSM into billet form; (2) the melting/remelting initial research focus will be on the use of radioactive surrogates to study; (3) the cost effectiveness of RSM processing oriented towards privatization of RSM reuse and/or resale. Other components of this problem that may be addressed under program extension are: (4) the melting/remelting of carbon steel; (5) the processing of billet material into product form which shall meet all applicable ASTM requirements; and, (6) the fabrication of an actual prototypical product; the present concept of an end product is a low carbon Type 304/316 stainless steel cylindrical container for densified and/or vitrified high level radioactive waste and/or the Universal Canister System for dry (interim) storage of spent fuel. The specific work reported herein covers the melting/remelting of stainless steel {open_quotes}scrap{close_quotes} metal into billet form and the study of surrogate material removal effectiveness by various remelting techniques.

Mizia, R.E. [ed.] [Westinghouse Idaho Nuclear Co., Idaho Falls, ID (United States). Metal Recycle; Atteridge, D.G.; Buckentin, J.; Carter, J.; Davis, H.L.; Devletian, J.H.; Scholl, M.R.; Turpin, R.B.; Webster, S.L. [Oregon Graduate Institute of Science and Technology, Portland, OR (United States). Dept. of Materials Science and Engineering

1994-08-01

410

Stabilisation of metal ions in unusual oxidation states and electron dynamics in oxide glasses  

NASA Astrophysics Data System (ADS)

The results of studies on the stabilisation of metal ions in unusual oxidation states in oxide glasses are surveyed. Attention is concentrated on the relation between the stabilisation of these ions and redistribution of the electron density, and on the disproportionation reactions accompanying it. The effect of reversible low-temperature disproportionation on niobium, titanium, vanadium, molybdenum, tungsten, and other ions is considered. The formation of metal clusters in oxide glasses is shown also to be associated with disproportionation. The bibliography includes 108 references.

Aleksandrov, A. I.; Prokof'ev, Alexandr I.; Bubnov, Nikolai N.

1996-06-01

411

Adherence of ion beam sputter deposited metal films on H-13 steel  

NASA Technical Reports Server (NTRS)

An electron bombardment argon ion source was used to sputter deposit 17 different metal and metal oxide films ranging in thickness from 1 to 8 micrometers on H-13 steel substrates. The film adherence to the substrate surface was measured using a tensile test apparatus. Comparisons in bond strength were made between ion beam, ion plating, and RF deposited films. A protective coating to prevent heat checking in H-13 steel dies used for aluminum die casting was studied. The results of exposing the coated substrates to temperatures up to 700 degrees are presented.

Mirtich, M. J.

1980-01-01

412

Comparison of synovial fluid, urine, and serum ion levels in metal-on-metal total hip arthroplasty at a minimum follow-up of 18 years.  

PubMed

Diagnosis of adverse reactions to metal debris in metal-on-metal hip arthroplasty is a multifactorial process. Systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urine, or synovial fluid levels and adverse local tissue reactions is still incompletely understood. The hypothesis was that elevated serum and urine metal-ion concentrations are associated with elevated local metal-ion concentrations in primary total hip arthroplasties (THA) and with failure of metal-on-metal articulations in the long-term. In our present study, we evaluated these concentrations in 105 cementless THA with metal-on-metal articulating surfaces with small head diameter at a minimum of 18 years postoperatively. Spearman correlation showed a high correlation between the joint fluid aspirate concentration of cobalt and chromium with the serum cobalt (r = 0.81) and chromium level (r = 0.77) in patients with the THA as the only source of metal-ions. In these patients serum metal-ion analysis is a valuable method for screening. In patients with more than one source of metal or renal insufficiency additional investigations, like joint aspirations are an important tool for evaluation of wear and adverse tissue reactions in metal-on-metal THA. PMID:24841922

Lass, Richard; Grübl, Alexander; Kolb, Alexander; Stelzeneder, David; Pilger, Alexander; Kubista, Bernd; Giurea, Alexander; Windhager, Reinhard

2014-09-01

413

Percolation of gallium dominates the electrical resistance of focused ion beam deposited metals  

SciTech Connect

Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

Faraby, H. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); DiBattista, M. [Qualcomm Technologies Incorporated, San Diego, California 92121 (United States); Bandaru, P. R., E-mail: pbandaru@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2014-04-28

414

Hydrogen transport through oxide metal surface under atom and ion irradiation  

NASA Astrophysics Data System (ADS)

Both the latest and earlier achieved results on gas exchange processes on metal surfaces (including stainless steel, titanium, zirconium, tungsten with deposited aluminum oxide coating) under hydrogen atom or plasma irradiation with occasional oxygen impurity are presented in the paper. Mechanisms and regularities of these processes are discussed. It is demonstrated that surface oxide layer properties as a diffusion barrier strongly depend on external influence on the surface. In particular, it is revealed that low energy hydrogen ion irradiation could slow down hydrogen desorption from metals. Hydrogen atom or ion irradiation combined with simultaneous oxygen admixture accelerates hydrogen desorption from metals.

Begrambekov, L.; Dvoychenkova, O.; Evsin, A.; Kaplevsky, A.; Sadovskiy, Ya; Schitov, N.; Vergasov, S.; Yurkov, D.

2014-11-01

415

Comparison of costs for solidification of high-level radioactive waste solutions: glass monoliths vs metal matrices  

SciTech Connect

A comparative economic analysis was made of four solidification processes for liquid high-level radioactive waste. Two processes produced borosilicate glass monoliths and two others produced metal matrix composites of lead and borosilicate glass beads and lead and supercalcine pellets. Within the uncertainties of the cost (1979 dollars) estimates, the cost of the four processes was about the same, with the major cost component being the cost of the primary building structure. Equipment costs and operating and maintenance costs formed only a small portion of the building structure costs for all processes.

Jardine, L.J.; Carlton, R.E.; Steindler, M.J.

1981-05-01

416

Comparison of costs for solidification of high-level radioactive waste solutions: Glass monoliths vs. metal matrices  

NASA Astrophysics Data System (ADS)

A comparative economic analysis was made of four solidification processes for liquid high-level radioactive waste. Two processes produced borosilicate glass monoliths and two others produced metal matric composites of lead and borosilicate glass beads and lead and supercalcine pellets. Within the uncertainties of the cost (1979 dollars) estimates, the cost of the four processes was about the same, with the major cost component being the cost of the primary building structure. Equipment costs and operating and maintenance costs formed only a small portion of the building structure costs for all processes.

Jardine, L. J.; Carlton, R. E.; Steindler, M. J.

1981-05-01

417

Preconcentration of Trace Metal Ions from Natural Waters: Studies on the Application of an Acrylic Ester Macroreticular Resin  

Microsoft Academic Search

A new preconcentration method has been developed for the determination of trace metals from natural waters. The method is based on the direct uptake of metal ions on a column packed with the macroporous acrylic ester resin, XAD-7, after interfering humic substances are removed on a XAD-7 precolumn. The retained metal ions are subsequently eluted with 1% v\\/v HNO? and

Solomon Ying Hung Chiang

1983-01-01

418

FINAL REPORT. RATIONAL DESIGN OF METAL ION SEQUESTERING AGENTS  

EPA Science Inventory

The purpose of this project has been to study the fundamental coordination chemistry of the actinides, uranium, thorium, plutonium and americium, and the non-radioactive analogues, cerium, iron, neodymium, and gadolinium, used as actinide models. Using a biomimetic approach we ha...

419

Metal ion interaction with cosubstrate in self-splicing of group I introns.  

PubMed Central

The catalytic mechanism for self-splicing of the group I intron in the pre-mRNA from the nrdB gene in bacteriophage T4 has been investigated using 2'-amino- 2'-deoxyguanosine or guanosine as cosubstrates in the presence of Mg2+, Mn2+and Zn2+. The results show that a divalent metal ion interacts with the cosubstrate and thereby influences the efficiency of catalysis in the first step of splicing. This suggests the existence of a metal ion that catalyses the nucleophilic attack of the cosubstrate. Of particular significance is that the transesterification reactions of the first step of splicing with 2'-amino-2'-deoxyguanosine as cosubstrate are more efficient in mixtures containing either Mn2+or Zn2+together with Mg2+than with only magnesium ions present. The experiments in metal ion mixtures show that two (or more) metal ions are crucial for the self-splicing of group I introns and suggest the possibility that more than one of these have a direct catalytic role. A working model for a two-metal-ion mechanism in the transesterification steps is suggested. PMID:9016608

Sjögren, A S; Pettersson, E; Sjöberg, B M; Strömberg, R

1997-01-01

420

Determination of environmentally important metal ions by fluorescence quenching in anionic micellar solution.  

PubMed

This work describes the effect of a variety of metal ions as quenchers of the fluorescence of naphthalene, in aqueous micellar solutions of sodium dodecyl sulfate (SDS). The quenching by the metal ions can be adequately described by the Stern-Volmer equation and the best signal to noise ratios are obtained with low micellized detergent concentrations. Apparent Stern-Volmer constants decrease in the order: Fe3+ > Cu2+ > Pb2+ > Cr3+ > Ni2+ and directly reflect the relative sensitivity of the method for these ions. Detection limits (defined as three times the standard deviation of the blank for n= 10) for the fluorescence quenching of naphthalene by the metal ions in aqueous micellar SDS are in the range of 1.0 x 10(-6) to 1.0 x 10(-5) mol dm(-3). The proposed fluorescence quenching method shows good repeatibility for a variety of added quencher metal ions, indicating that anionic micelle-enhanced fluorescence quenching by metal ions constitutes an analytical method of rather general application. PMID:15665980

Vargas, Leonardo V; Sand, Juergen; Brandão, Tiago A S; Fiedler, Haidi D; Quina, Frank H; Nome, Faruk

2005-02-01

421

Surface enhanced Raman spectroscopy as a new spectral technique for quantitative detection of metal ions  

NASA Astrophysics Data System (ADS)

Four newly synthesized poly (propylene amine) dendrimers from first and second generation modified with 1,8-naphthalimide units in the dendrimer periphery have been investigated as ligands for the detection of heavy metal ions (Al3+, Sb2+, As2+, Cd2+ and Pb2+) by surface-enhanced Raman spectroscopy. Calibration curves were established for all metal ions between the concentration ranges of  1 x 10-6 to 5 x 10-4 M. It has been shown that these dendrimers can be coordinated, especially with different metal ions. Using dendrimer molecules and silver colloids at the same time allowed us to obtain an SERS signal from the abovementioned metal ions at very low concentrations. Principle component analysis (PCA) analysis was also applied to the collected SERS data. Four differentPCA models were developed to accomplish the discrimination of five metal ions, which interacted with each of the four dendrimer molecules, separately. A detailed investigation was performed in the present study to provide the basis of a new approach for heavy met