WorldWideScience

Sample records for cobalt dicarbollide-based universal

  1. Recent advances in the development of a cobalt dicarbollide based solvent extraction process for the separation of Cs and Sr from spent fuel

    International Nuclear Information System (INIS)

    Law, Jack D.; Todd, Terry A.; Peterman, D.R.; Herbst, R.S.; Tillotson, R.D.

    2004-01-01

    As part of the Advanced Fuel Cycle Initiative (AFCI), a chlorinated cobalt dicarbollide (CCD)/polyethylene glycol (PEG) based solvent extraction process is being developed for the separation of Cs and Sr from leached spent light water reactor (LWR) fuel. The separation of Cs and Sr would significantly reduce the short-term heat generation of spent nuclear fuel requiring geological disposal. Recent advances in the development of a CCD/PEG process will be presented. The data presented will include acid dependency data, results of batch contact testing using simulant feeds traced with 137 Cs, 90 Sr and 241 Am as well as results of testing to evaluate extractant composition. The impacts of other separation process in an advanced aqueous separation flow sheet on the effectiveness of the CCD/PEG process will be detailed. (authors)

  2. Cobalt

    Science.gov (United States)

    Slack, John F.; Kimball, Bryn E.; Shedd, Kim B.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Cobalt is a silvery gray metal that has diverse uses based on certain key properties, including ferromagnetism, hardness and wear-resistance when alloyed with other metals, low thermal and electrical conductivity, high melting point, multiple valences, and production of intense blue colors when combined with silica. Cobalt is used mostly in cathodes in rechargeable batteries and in superalloys for turbine engines in jet aircraft. Annual global cobalt consumption was approximately 75,000 metric tons in 2011; China, Japan, and the United States (in order of consumption amount) were the top three cobalt-consuming countries. In 2011, approximately 109,000 metric tons of recoverable cobalt was produced in ores, concentrates, and intermediate products from cobalt, copper, nickel, platinum-group-element (PGE), and zinc operations. The Democratic Republic of the Congo (Congo [Kinshasa]) was the principal source of mined cobalt globally (55 percent). The United States produced a negligible amount of byproduct cobalt as an intermediate product from a PGE mining and refining operation in southeastern Montana; no U.S. production was from mines in which cobalt was the principal commodity. China was the leading refiner of cobalt, and much of its production came from cobalt ores, concentrates, and partially refined materials imported from Congo (Kinshasa).The mineralogy of cobalt deposits is diverse and includes both primary (hypogene) and secondary (supergene) phases. Principal terrestrial (land-based) deposit types, which represent most of world’s cobalt mine production, include primary magmatic Ni-Cu(-Co-PGE) sulfides, primary and secondary stratiform sediment-hosted Cu-Co sulfides and oxides, and secondary Ni-Co laterites. Seven additional terrestrial deposit types are described in this chapter. The total terrestrial cobalt resource (reserves plus other resources) plus past production, where available, is calculated to be 25.5 million metric tons. Additional resources of

  3. Cobalt

    International Nuclear Information System (INIS)

    Stolyarova, I.A.; Bunakova, N.Yu.

    1983-01-01

    The neutron-activation method for determining cobalt in rocks, polymetallic and iron ores and rockforming minerals at 2x10 -6 -5x10 -3 % content is developed. Cobalt determination is based on the formation under the effect of thermal neutrons of nuclear reactor of the 60 Co radioactive isotope by the 59 Co (n, γ) 60 Co reaction with radiation energy of the most intensive line of 1333 keV. Cobalt can be determined by the scheme of the multicomponent analysis from the sample with other elements. Co is determined in the solution after separation of all determinable by the scheme elements. The 60 Co intensity is measured by the mUltichannel gamma-spectrometer with Ge(Li)-detector

  4. Characterization of feline serum-cobalt binding.

    Science.gov (United States)

    Schnelle, Amy N; Barger, Anne M; MacNeill, Amy L; Mitchell, Mark M; Solter, Philip

    2015-06-01

    Oxidative stress inhibits albumin's ability to complex with cobalt. Feline serum-cobalt binding has not been described. The objective was to develop a cobalt binding test for use with feline serum, and correlate the results with other biochemical and cellular constituents in blood, and with clinical diseases of cats. A colorimetric test of cobalt binding, based on the oxidation-reduction reaction of Co(+2) and dithiothreitol, was developed using feline serum. The test was used to measure cobalt binding in stored serum from 176 cats presented to the University of Illinois Veterinary Teaching Hospital for a variety of disease conditions. Time-matched hematology and biochemical data, and clinical information, were obtained from the medical record of each cat and correlated with the serum-cobalt binding results. Serial dilution of feline serum with phosphate-buffered saline resulted in a highly linear decrease in serum-cobalt binding (r(2)  = .9984). Serum-cobalt binding of the clinical samples also correlated with albumin concentrations in a stepwise linear regression model (r(2)  = .425), and both cobalt binding and albumin were significantly decreased in cases of inflammation. Albumin and cobalt binding also shared significant correlations with several erythron variables, and serum concentration of total calcium and bilirubin. The correlation of cobalt binding measured by a colorimetric test with albumin concentration in the clinical samples and with serum dilution is consistent with feline albumin-cobalt complex formation. Hypoalbuminemia is the likely cause of reduced serum-cobalt binding in inflammation and the correlations observed between cobalt binding and other variables. © 2015 American Society for Veterinary Clinical Pathology.

  5. Unconventional superconductivity in cuprates, cobaltates and graphene. What is universal and what is material-dependent in strongly versus weakly correlated materials?

    International Nuclear Information System (INIS)

    Kiesel, Maximilian Ludwig

    2013-01-01

    A general theory for all classes of unconventional superconductors is still one of the unsolved key issues in condensed-matter physics. Actually, it is not yet fully settled if there is a common underlying pairing mechanism. Instead, it might be possible that several distinct sources for unconventional (not phonon-mediated) superconductivity have to be considered, or an electron-phonon interaction is not negligible. The focus of this thesis is on the most probable mechanism for the formation of Cooper pairs in unconventional superconductors, namely a strictly electronic one where spin fluctuations are the mediators. Studying different superconductors in this thesis, the emphasis is put on material-independent features of the pairing mechanism. In addition, the investigation of the phase diagrams enables a view on the vicinity of superconductivity. Thus, it is possible to clarify which competing quantum fluctuations enhance or weaken the propensity for a superconducting state. The broad range of superconducting materials requires the use of more than one numerical technique to study an appropriate microscopic description. This is not a problem but a big advantage because this facilitates the approach-independent description of common underlying physics. For this evaluation, the strongly correlated cuprates are simulated with the variational cluster approach. Especially the question of a pairing glue is taken into consideration. Furthermore, it is possible to distinguish between retarded and non-retarded contributions to the gap function. The cuprates are confronted with the cobaltate Na x CoO 2 and graphene. These weakly correlated materials are investigated with the functional renormalization group (fRG) and reveal a comprehensive phase diagram, including a d+id-wave superconductivity, which breaks time-reversal symmetry. The corresponding gap function is nodeless, but for NaCoO, it features a doping-dependent anisotropy. In addition, some general considerations on

  6. Unconventional superconductivity in cuprates, cobaltates and graphene. What is universal and what is material-dependent in strongly versus weakly correlated materials?

    Energy Technology Data Exchange (ETDEWEB)

    Kiesel, Maximilian Ludwig

    2013-02-08

    A general theory for all classes of unconventional superconductors is still one of the unsolved key issues in condensed-matter physics. Actually, it is not yet fully settled if there is a common underlying pairing mechanism. Instead, it might be possible that several distinct sources for unconventional (not phonon-mediated) superconductivity have to be considered, or an electron-phonon interaction is not negligible. The focus of this thesis is on the most probable mechanism for the formation of Cooper pairs in unconventional superconductors, namely a strictly electronic one where spin fluctuations are the mediators. Studying different superconductors in this thesis, the emphasis is put on material-independent features of the pairing mechanism. In addition, the investigation of the phase diagrams enables a view on the vicinity of superconductivity. Thus, it is possible to clarify which competing quantum fluctuations enhance or weaken the propensity for a superconducting state. The broad range of superconducting materials requires the use of more than one numerical technique to study an appropriate microscopic description. This is not a problem but a big advantage because this facilitates the approach-independent description of common underlying physics. For this evaluation, the strongly correlated cuprates are simulated with the variational cluster approach. Especially the question of a pairing glue is taken into consideration. Furthermore, it is possible to distinguish between retarded and non-retarded contributions to the gap function. The cuprates are confronted with the cobaltate Na{sub x}CoO{sub 2} and graphene. These weakly correlated materials are investigated with the functional renormalization group (fRG) and reveal a comprehensive phase diagram, including a d+id-wave superconductivity, which breaks time-reversal symmetry. The corresponding gap function is nodeless, but for NaCoO, it features a doping-dependent anisotropy. In addition, some general

  7. Cobalt sensitization and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P

    2012-01-01

    : This clinical review article presents clinical and scientific data on cobalt sensitization and dermatitis. It is concluded that cobalt despite being a strong sensitizer and a prevalent contact allergen to come up on patch testing should be regarded as a very complex metal to test with. Exposure...... data together with clinical data from metal workers heavily exposed to cobalt suggest that patch-test reactions are sometimes false positive and that patch testers should carefully evaluate their clinical relevance....

  8. The geobiochemistry of cobalt.

    Science.gov (United States)

    Hamilton, E I

    1994-06-30

    In the crust of the Earth cobalt is present in a greater abundance than lead, molybdenum or cadmium. The concentration and distribution of cobalt is discussed in relation to major terrestrial, aquatic and atmospheric systems. The processes which control or influence the transfer of this element in major ecosystems are evaluated in terms of bioavailability to plants, animals and man. The concept of geochemical provinces is considered in relation to the regional availability of cobalt and then its transfer along foodchains to man. Areas and environments which contain high or low concentrations of cobalt are considered in relation to the health of plants, animals and man; the special case of exposure to cobalt from the manufacturing industry is discussed. The association between cobalt and hard metal disease is noted. The use of various radionuclides of cobalt is considered as a means of tracing cobalt through complex ecosystems. The state of the art for measuring the concentration of cobalt is discussed with special reference to the quality of analytical data and the availability of suitable reference materials.

  9. Nanocrystalline Iron-Cobalt Alloys for High Saturation Indutance

    Science.gov (United States)

    2016-02-24

    AFRL-AFOSR-VA-TR-2016-0263 Nanocrystalline Iron- Cobalt Alloys for High saturation Indutance Conrad Williams MORGAN STATE UNIVERSITY (INC) 1700 E...YYYY) 28-02-2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) 01 March 2013 -28 February 2016 4. TITLE AND SUBTITLE Nanocrystalline Iron- Cobalt ...driving the research at Morgan State University is “Can one achieve high magnetization (B > 1.7 T) at low fields (H < 1 mT) in iron- cobalt

  10. Electrodeposition of Cobalt Nanowires

    International Nuclear Information System (INIS)

    Ahn, Sungbok; Hong, Kimin

    2013-01-01

    We developed an electroplating process of cobalt nanowires of which line-widths were between 70 and 200 nm. The plating electrolyte was made of CoSO 4 and an organic additive, dimethyldithiocarbamic acid ester sodium salt (DAESA). DAESA in plating electrolytes had an accelerating effect and reduced the surface roughness of plated cobalt thin films. We obtained void-free cobalt nanowires when the plating current density was 6.25 mA/cm 2 and DAESA concentration was 1 mL/L

  11. Phosphine modified cobalt hydroformylation

    Energy Technology Data Exchange (ETDEWEB)

    Rensburg, H. van; Tooze, R.P.; Foster, D.F. [Sasol Technology UK, St. Andrews (United Kingdom); Janse van Rensburg, W. [Sasol Technology, Sasolburg (South Africa)

    2006-07-01

    An ongoing challenge in phosphine modified cobalt hydroformylation is the fundamental understanding of the electronic and steric properties of phosphine ligands that influence the selectivity and activity of the catalytic reaction. A series of acyclic and cyclic phosphines have been prepared and tested in phosphine modified cobalt hydroformylation of 1-octene. Molecular modelling on a series of phospholanes showed some interesting theoretical and experimental correlations. We also evaluated the use of N-heterocyclic carbenes as an alternative for phosphines in modified cobalt hydroformylation. (orig.)

  12. Cobalt release from inexpensive jewellery

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten Stendahl; Menné, Torkil

    2010-01-01

    . Conclusions: This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future....... Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Results: Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin-cobalt plating on these...

  13. Wrought cobalt- base superalloys

    Science.gov (United States)

    Klarstrom, D. L.

    1993-08-01

    Wrought cobalt-base superalloys are used extensively in gas turbine engines because of their excellent high-temperature creep and fatigue strengths and resistance to hot corrosion attack. In addition, the unique character of the oxide scales that form on some of the alloys provides outstanding resistance to high-temperature sliding wear. This article provides a review of the evolutionary development of wrought cobalt-base alloys in terms of alloy design and physical metallurgy. The topics include solid-so-lution strengthening, carbide precipitation characteristics, and attempts to introduce age hardening. The use of PHACOMP to enhance thermal stability characteristics and the incorporation of rare-earth ele-ments to improve oxidation resistance is also reviewed and discussed. The further development of cobalt-base superalloys has been severely hampered by past political events, which have accentuated the strategic vulnerability of cobalt as a base or as an alloying element. Consequently, alternative alloys have been developed that use little or no cobalt. One such alternative, Haynes® 230TMalloy, is discussed briefly.

  14. The Idaho cobalt belt

    Science.gov (United States)

    Bookstrom, Arthur A.

    2013-01-01

    The Idaho cobalt belt (ICB) is a northwest-trending belt of cobalt (Co) +/- copper (Cu)-bearing deposits and prospects in the Salmon River Mountains of east-central Idaho, U.S.A. The ICB is about 55 km long and 10 km long in its central part, which contains multiple strata-bound ore zones in the Blackbird mine area. The Black Pine and Iron Creek Co-Cu prospects are southeast of Blackbird, and the Tinkers Pride, Bonanza Copper, Elk Creek, and Salmon Canyon Copper prospects are northwest of Blackbird.

  15. Cobalt/Fullerene Spinterfaces

    NARCIS (Netherlands)

    Wang, Kai

    2015-01-01

    Spintronics is a multidisciplinary research field and it explores phenomena that interlink the spin and charge degrees of freedom. The thesis focuses on spin-polarized electronic transports in cobalt (Co) and fullerene (C60) based vertical spintronic devices. It starts with a review about

  16. cobalt (ii), nickel (ii)

    African Journals Online (AJOL)

    DR. AMINU

    ABSTRACT. The manganese (II), cobalt (II), nickel (II) and copper (II) complexes of N, N' – bis(benzoin)ethylenediiminato have been prepared and characterized by infrared, elemental analysis, conductivity measurements and solubility. The potentiometric, and elemental analyses studies of the complexes revealed 1:1 ...

  17. High density nonmagnetic cobalt in thin films

    OpenAIRE

    Banu, Nasrin; Singh, Surendra; Basu, Saibal; Roy, Anupam; Movva, Hema C. P.; Dev, B. N.

    2017-01-01

    Recently high density (HD) nonmagnetic (NM) cobalt has been discovered in a cobalt thin film, grown on Si(111). This cobalt film had a natural cobalt oxide at the top. The oxide layer forms when the film is taken out of the electron-beam deposition chamber and exposed to air. Thin HD NM cobalt layers were found near the cobalt/silicon and the cobalt-oxide/cobalt interfaces, while the thicker mid-depth region of the film was hcp cobalt with normal density and normal magnetic moment. If an ultr...

  18. Osmium and cobalt complexes incorporating facially coordinated N ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 1. Osmium and cobalt complexes incorporating ... Mary F Mahon2 Surajit Chattopadhyay1. Department of Chemistry, University of Kalyani, Kalyani 741235, India; Department of Inorganic Chemistry, University of Bath, Claverton Down, Bath, BA27AY, UK ...

  19. Elicitation threshold of cobalt chloride

    DEFF Research Database (Denmark)

    Fischer, Louise A; Johansen, Jeanne D; Voelund, Aage

    2016-01-01

    BACKGROUND: Cobalt is a strong skin sensitizer (grade 5 of 5 in the guinea-pig maximization test) that is used in various industrial and consumer applications. To prevent sensitization to cobalt and elicitation of allergic cobalt dermatitis, information about the elicitation threshold level...... of cobalt is important. OBJECTIVE: To identify the dermatitis elicitation threshold levels in cobalt-allergic individuals. MATERIALS AND METHODS: Published patch test dose-response studies were reviewed to determine the elicitation dose (ED) levels in dermatitis patients with a previous positive patch test...... reaction to cobalt. A logistic dose-response model was applied to data collected from the published literature to estimate ED values. The 95% confidence interval (CI) for the ratio of mean doses that can elicit a reaction in 10% (ED(10)) of a population was calculated with Fieller's method. RESULTS...

  20. Nickel, cobalt, and their alloys

    CERN Document Server

    2000-01-01

    This book is a comprehensive guide to the compositions, properties, processing, performance, and applications of nickel, cobalt, and their alloys. It includes all of the essential information contained in the ASM Handbook series, as well as new or updated coverage in many areas in the nickel, cobalt, and related industries.

  1. Continuous removal of radioactive cobalt from water

    International Nuclear Information System (INIS)

    Silver, G.L.

    1987-01-01

    More than 99% of radioactive cobalt can be removed from water by precipitation as cobalt(III) hydroxide. The process is continuous and uses either sodium hypochlorite or oxygen and calcium sulfite to oxidize the cobalt. Carbonate and phosphate interfere with cobalt removal, but the process has potential for other applications such as thallium removal and sewage treatment. (author)

  2. The effect of vitamin C and cobalt supplementation on antioxidant ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-05

    Oct 5, 2009 ... Full Length Research Paper. The effect of vitamin C and cobalt supplementation on antioxidant status in healthy and diabetic rats. Özlem Yildirim. Ankara University, Faculty of Science, Department of Biology, 06100, Tandogan, Ankara, Turkey. E -mail: yildirim@science.ankara.edu.tr Tel: +90-312-212-6720 ...

  3. Synthesis and characterization of gel-grown cobalt tartrate crystals

    Indian Academy of Sciences (India)

    3Department of Physics, Mongolian University of Science and Technology, Ulaanbaatar, Mongolia. ∗. Corresponding .... The indexed XRD data for cobalt tartrate crystals are shown in table 2. The indexing was .... Manimaran, Head, Marketing, Pricol Castings Ltd, Coimbatore for the support during the course of this work.

  4. Characterization of a Cobalt-Tungsten Interconnect

    DEFF Research Database (Denmark)

    Harthøj, Anders; Holt, Tobias; Caspersen, Michael

    2012-01-01

    A ferritic steel interconnect for a solid oxide fuel cell must be coated in order to prevent chromium evaporation from the steel substrate. The Technical University of Denmark and Topsoe Fuel Cell have developed an interconnect coating based on a cobalt-tungsten alloy. The purpose of the coating...... for 300 h at 800 °C. The coating was characterized with Glow Discharge Optical Spectroscopy (GDOES), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The oxidation properties were evaluated by measuring weight change of coated samples of Crofer 22 H and Crofer 22 APU as a function...

  5. Electrocatalytic Activity of Electropolymerized Cobalt ...

    African Journals Online (AJOL)

    NICO

    2010-09-20

    Sep 20, 2010 ... KEYWORDS. Electrocatalysis, 6-mercaptopurine, 2-mercaptobenzimidazole, cobalt tetraaminophthalocyanine, electropolymeric film. 1. Introduction ... have been used to prepare polymeric film modified electrodes; among them ... ultrasonicated thoroughly in 50.0 % nitric acid, ethanol and distilled water ...

  6. Cobalt: for strength and color

    Science.gov (United States)

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  7. Universe

    CERN Document Server

    Doudna, Kelly

    2015-01-01

    The Universe explores the science of what we see in the night sky. Kids will learn about the life cycle of a star, find out how our universe was created, explore nebulae, galaxies, black holes, giant stars and more. Engaging photos, exciting graphics, and a fun quiz at the end of each book will keep them learning. Aligned to Common Core Standards and correlated to state standards. Super Sandcastle is an imprint of Abdo Publishing, a division of ABDO.

  8. COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

    Directory of Open Access Journals (Sweden)

    Liudmila V. Dyakova

    2010-06-01

    Full Text Available The paper deals with the extracting cobalt salts by using mixtures on the basis of tertiary amine from multicomponent solutions from the process of hydrochloride leaching of cobalt concentrate. The optimal composition for the extraction mixture, the relationship between the cobalt distribution coefficients and modifier’s nature and concentration, and the saltingout agent type have been determined. A hydrochloride extraction technology of cobalt concentrate yielding a purified concentrated cobalt solution for the production of pure cobalt salts has been developed and introduced at Severonikel combine.

  9. AN ELECTROPLATING METHOD OF FORMING PLATINGS OF NICKEL, COBALT, NICKEL ALLOYS OR COBALT ALLOYS

    DEFF Research Database (Denmark)

    1997-01-01

    An electroplating method of forming platings of nickel, cobalt, nickel alloys or cobalt alloys with reduced stresses in an electrodepositing bath of the type: Watt's bath, chloride bath or a combination thereof, by employing pulse plating with periodic reverse pulse and a sulfonated naphthalene...... additive. This method makes it possible to deposit nickel, cobalt, nickel or cobalt platings without internal stresses....

  10. Phosphorus introduction mechanism in electrodeposited cobalt films

    International Nuclear Information System (INIS)

    Kravtchenko, Jean-Francois

    1973-01-01

    The cathodic reduction of hypophosphite, phosphite and phosphate ions was studied using chrono-potentiometry and voltammetry. Then cobalt was deposited at constant current from a bath containing one of these three compounds. The current, while giving an electrodeposition of cobalt, also enhances at the same time a chemical deposition of cobalt. It is shown that high coercive forces in cobalt films are much more related to this chemical deposition than to the simple fact that the films contain some phosphorus. (author) [fr

  11. Transport of cobalt-60 industrial radiation sources

    Science.gov (United States)

    Kunstadt, Peter; Gibson, Wayne

    This paper will deal with safety aspects of the handling of Cobalt-60, the most widely used industrial radio-isotope. Cobalt-60 is a man-made radioisotope of Cobalt-59, a naturally occurring non radioactive element, that is made to order for radiation therapy and a wide range of industrial processing applications including sterilization of medical disposables, food irradiation, etc.

  12. Cobalt-containing alloys and their ability to release cobalt and cause dermatitis.

    Science.gov (United States)

    Julander, Anneli; Hindsén, Monica; Skare, Lizbet; Lidén, Carola

    2009-03-01

    Cobalt, nickel, and chromium are important skin sensitizers. However, knowledge about cobalt exposure and causes of cobalt sensitization is limited. To study release of cobalt, nickel, and chromium from some cobalt-containing hard metal alloys and to test reactivity to the materials in cobalt-sensitized patients. Discs suitable for patch testing were made of some hard metal alloys. Cobalt, nickel, and chromium release from the materials was determined by immersion in artificial sweat (2 min, 1 hr, 1 day, and 1 week). Patch test reactivity to the discs and to serial dilutions of cobalt and nickel was assessed in previously patch-tested dermatitis patients (19 cobalt positive and 18 cobalt-negative controls). All discs released cobalt, nickel, and chromium. Some discs released large amounts of cobalt (highest concentration: 290 microg/cm(2)/week). Seven discs elicited three or more positive test reactions. The concentration of released cobalt was high enough to elicit allergic contact dermatitis in cobalt-sensitized patients. As the materials in the discs are used in wear parts of hard metal tools, individuals with contact allergy to cobalt may develop hand eczema when handling such materials.

  13. Cobalt production in RAPS-1

    International Nuclear Information System (INIS)

    Krishnan, P.D.; Purandare, H.D.

    1978-01-01

    At present in RAPS-1 radioisotope Co 60 is produced by irradiating Co 59 in the adjusters which perform the function of regulation of reactivity, power and xenon override. But the manrem expenditure of the crew handling the charge and discharge of the adjusters is going to be prohibitively high. It is therefore proposed to irradiate Co 59 in the fuel channel positions. The physics optimisation study for such irradiation is presented. The burnup penalty and loss of power are estimated to produce the required quantity of Co 60 after optimising the number of cobalt pencils in a bundle and the positions of the cobalt producing channels in the reactor core. (author)

  14. Universe

    CERN Document Server

    2009-01-01

    The Universe, is one book in the Britannica Illustrated Science Library Series that is correlated to the science curriculum in grades 5-8. The Britannica Illustrated Science Library is a visually compelling set that covers earth science, life science, and physical science in 16 volumes.  Created for ages 10 and up, each volume provides an overview on a subject and thoroughly explains it through detailed and powerful graphics-more than 1,000 per volume-that turn complex subjects into information that students can grasp.  Each volume contains a glossary with full definitions for vocabulary help and an index.

  15. Universe

    CERN Document Server

    2011-01-01

    Updated for 2011, the Universe, is one book in the Britannica Illustrated Science Library Series that covers today's most popular science topics, from digital TV to microchips to touchscreens and beyond. Perennial subjects in earth science, life science, and physical science are all explored in detail. Amazing graphics-more than 1,000 per title-combined with concise summaries help students understand complex subjects. Correlated to the science curriculum in grades 5-9, each title also contains a glossary with full definitions for vocabulary.

  16. Cobalt(II) and Cobalt(III) Coordination Compounds.

    Science.gov (United States)

    Thomas, Nicholas C.; And Others

    1989-01-01

    Presents a laboratory experiment which illustrates the formation of tris(phenanthroline)cobalt complexes in the 2+ and 3+ oxidation states, the effect of coordination on reactions of the ligand, and the use of a ligand displacement reaction in recovering the transformed ligand. Uses IR, UV-VIS, conductivity, and NMR. (MVL)

  17. Electrocatalytic Activity of Electropolymerized Cobalt ...

    African Journals Online (AJOL)

    NICO

    2010-09-20

    Sep 20, 2010 ... The electrocatalytic activity of electropolymerized cobalt tetraaminophthalocyanine (poly-CoTAPc) film modified on the glassy carbon electrode ... nation of these sulphhydryl compounds in human metabolism is essential for .... adduct product was formed by the coordination axially between. Co(II)TAPc and ...

  18. The cobalt-60 container scanner

    International Nuclear Information System (INIS)

    Jigang, A.; Liye, Z.; Yisi, L.; Haifeng, W.; Zhifang, W.; Liqiang, W.; Yuanshi, Z.; Xincheng, X.; Furong, L.; Baozeng, G.; Chunfa, S.

    1997-01-01

    The Institute of Nuclear Energy Technology (INET) has successfully designed and constructed a container (cargo) scanner, which uses cobalt-60 of 100-300 Ci as radiation source. The following performances of the Cobalt-60 container scanner have been achieved at INET: a) IQI (Image Quality Indicator) - 2.5% behind 100 mm of steel; b) CI (Contrast Indicator) - 0.7% behind 100 mm of steel; c) SP (Steel Penetration) - 240 mm of steel; d) Maximum Dose per Scanning - 0.02mGy; e) Throughput - twenty 40-foot containers per hour. These performances are equal or similar to those of the accelerator scanners. Besides these nice enough inspection properties, the Cobalt-60 scanner possesses many other special features which are better than accelerator scanners: a) cheap price - it will be only or two tenths of the accelerator scanner's; b) low radiation intensity - the radiation protection problem is much easier to solve and a lot of money can be saved on the radiation shielding building; c) much smaller area for installation and operation; d) simple operation and convenient maintenance; e) high reliability and stability. The Cobalt-60 container (or cargo) scanner is satisfied for boundary customs, seaports, airports and railway stations etc. Because of the nice special features said above, it is more suitable to be applied widely. Its high properties and low price will make it have much better application prospects

  19. Cobalt 60 commercial irradiation facilities

    International Nuclear Information System (INIS)

    West, G.

    1985-01-01

    The advantage of using cobalt 60 for ionizing treatment is that it has excellent penetration. Gamma plants are also very efficient, in as much as there is very little mechanical or electrical equipment in a gamma irradiation facility. The average efficiency of a gamma plant is usually around 95% of all available processing time

  20. Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

    Science.gov (United States)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil; Lidén, Carola; Julander, Anneli; Møller, Per; Johansen, Jeanne Duus

    2010-08-01

    Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure. The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. The cobalt spot test was used to assess cobalt release from all items. Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin-cobalt plating on these. This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future. Industries may not be fully aware of the potential cobalt allergy problem.

  1. Polytypic transformations during the thermal decomposition of cobalt hydroxide and cobalt hydroxynitrate

    International Nuclear Information System (INIS)

    Ramesh, Thimmasandra Narayan

    2010-01-01

    The isothermal decomposition of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature leads to the formation of Co 3 O 4 . The phase evolution during the decomposition process was monitored using powder X-ray diffraction. The transformation of cobalt hydroxide to cobalt oxide occurs via three phase mixture while cobalt hydroxynitrate to cobalt oxide occurs through a two phase mixture. The nature of the sample and its preparation method controls the decomposition mechanism. The comparison of topotactical relationship between the precursors to the decomposed product has been reported in relation to polytypism. - Graphical abstract: Isothermal thermal decomposition studies of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature show the metastable phase formed prior to Co 3 O 4 phase.

  2. Recovery of Cobalt as Cobalt Oxalate from Cobalt Tailings Using Moderately Thermophilic Bioleaching Technology and Selective Sequential Extraction

    Directory of Open Access Journals (Sweden)

    Guobao Chen

    2016-07-01

    Full Text Available Cobalt is a very important metal which is widely applied in various critical areas, however, it is difficult to recover cobalt from minerals since there is a lack of independent cobalt deposits in nature. This work is to provide a complete process to recover cobalt from cobalt tailings using the moderately thermophilic bioleaching technology and selective sequential extraction. It is found that 96.51% Co and 26.32% Cu were extracted after bioleaching for four days at 10% pulp density. The mean compositions of the leach solutions contain 0.98 g·L−1 of Co, 6.52 g·L−1 of Cu, and 24.57 g·L−1 of Fe (III. The copper ion was then recovered by a solvent extraction process and the ferric ions were selectively removed by applying a goethite deironization process. The technological conditions of the above purification procedures were deliberately discussed. Over 98.6% of copper and 99.9% of ferric ions were eliminated from the leaching liquor. Cobalt was finally produced as cobalt oxalate and its overall recovery during the whole process was greater than 95%. The present bioleaching process of cobalt is worth using for reference to deal with low-grade cobalt ores.

  3. Cobalt toxicity in anaerobic granular sludge: influence of chemical speciation

    NARCIS (Netherlands)

    Bartacek, J.; Fermoso, F.G.; Baldo-Urrutia, A.M.; Hullebusch, van E.D.; Lens, P.N.L.

    2008-01-01

    The influence of cobalt speciation on the toxicity of cobalt to methylotrophic methanogenesis in anaerobic granular sludge was investigated. The cobalt speciation was studied with three different media that contained varying concentrations of complexing ligands [carbonates, phosphates and

  4. Mineral resource of the month: cobalt

    Science.gov (United States)

    Shedd, Kim B.

    2009-01-01

    Cobalt is a metal used in numerous commercial, industrial and military applications. On a global basis, the leading use of cobalt is in rechargeable lithium-ion, nickel-cadmium and nickel-metal hydride battery electrodes. Cobalt use has grown rapidly since the early 1990s, with the development of new battery technologies and an increase in demand for portable electronics such as cell phones, laptop computers and cordless power tools.

  5. Derivative spectrophotometry of cobalt alloys

    International Nuclear Information System (INIS)

    Spitsyn, P.K.

    1985-01-01

    The method of derivative spectrophotometry is briefly described, and derivative absorption spectra are presented for samarium, cobalt, and commercial Sm-Co alloys. It is shown that the use of derivative spectrophotometry not only improves the accuracy and selectivity of element determinations but also simplifies the analysis of alloys. Results of a statistical evaluation of the metrological characteristics of the analytical procedure described here are presented. 8 references

  6. Cobalt release from implants and consumer items and characteristics of cobalt sensitized patients with dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Menne, Torkil; Liden, Carola

    2012-01-01

    -containing dental alloys and revised hip implant components.Results. Six of eight dental alloys and 10 of 98 revised hip implant components released cobalt in the cobalt spot test, whereas none of 50 mobile phones gave positive reactions. The clinical relevance of positive cobalt test reactions was difficult...

  7. EFTF cobalt test assembly results

    International Nuclear Information System (INIS)

    Rawlins, J.A.; Wootan, D.W.; Carter, L.L.; Brager, H.R.; Schenter, R.E.

    1988-01-01

    A cobalt test assembly containing yttrium hydride pins for neutron moderation was irradiated in the Fast Flux Test Facility during Cycle 9A for 137.7 equivalent full power days at a power level fo 291 MW. The 36 test pins consisted of a batch of 32 pins containing cobalt metal to produce Co-60, and a set of 4 pins with europium oxide to produce Gd-153, a radioisotope used in detection of the bone disease Osteoporosis. Post-irradiation examination of the cobalt pins determined the Co-60 produced with an accuracy of about 5 %. The measured Co-60 spatially distributed concentrations were within 20 % of the calculated concentrations. The assembly average Co-60 measured activity was 4 % less than the calculated value. The europium oxide pins were gamma scanned for the europium isotopes Eu-152 and Eu-154 to an absolute accuracy of about 10 %. The measured europium radioisotpe anc Gd-153 concentrations were within 20 % of calculated values. In conclusion, the hydride assembly performed well and is an excellent vehicle for many Fast Flux Test Facility isotope production applications. The results also demonstrate that the calculational methods developed by the Westinghouse Hanford Company are very accurate. (author)

  8. Spectrophotometric determination of cobalt with phenanthrenequinone monoxime.

    Science.gov (United States)

    Trikha, K C; Katyal, M; Singh, R P

    1967-08-01

    Phenanthrenequinone monoxime reacts with cobalt to form a yellow-orange insoluble 1:3 (cobalt:ligand) complex which is extractable into chloroform in the pH range 4.45-8.0. The determination of cobalt is carried out at 470 mmu. Beer's law is obeyed over the concentration range 0-3.0 ppm of cobalt. The sensitivity is 0-00336 mug of Co/cm(2) for 0.001 absorbance. The effect of a number of foreign ions has been studied.

  9. Cobalt accumulation and circulation by blackgum trees

    International Nuclear Information System (INIS)

    Thomas, W.A.

    1975-01-01

    Blackgum (Nyssa sylvatica Marsh.) trees accumulate far greater concentrations of cobalt in mature foliage than do other species on the same site (363 ppM in ash of blackgum, compared with about 3 ppM by mockernut hickory and about 1 ppM by red maple, tulip tree, and white oak). Cobalt concentrations in dormant woody tissues of blackgum also significantly exceed those in the other four species. Inoculation of six blackgums with 60 Co revealed that cobalt remains mobile in the trees for at least 3 years. Foliar concentrations of stable cobalt increase uniformly until senescence. In late August, foliage accounts for only 9 percent of total tree weight but 57 percent of total tree cobalt. Losses of cobalt from trees occur almost entirely by leaf abscission, and the loss rates of weight and cobalt from decomposing litter are similar. Retention of cobalt in the biologically active soil layers perpetuates zones of cobalt concentration created by this species in woodlands

  10. Cobalt-chitosan: Magnetic and biodegradable heterogeneous ...

    Indian Academy of Sciences (India)

    A novel and biodegradable cobalt-chitosan as a magnetic heterogeneous catalyst was synthesized and characterized by XPS, FT-IR, EDX and TEM. Catalytic performance of cobalt- chitosan was tested by aerobic oxidation of alkyl arenes and alcohols. The results show that the catalyst exhibits excellent conversion for ...

  11. Cobalt-chitosan: Magnetic and biodegradable heterogeneous ...

    Indian Academy of Sciences (India)

    Abstract. A novel and biodegradable cobalt-chitosan as a magnetic heterogeneous catalyst was synthesized and characterized by XPS, FT-IR, EDX and TEM. Catalytic performance of cobalt- chitosan was tested by aerobic oxidation of alkyl arenes and alcohols. The results show that the catalyst exhibits excellent ...

  12. Cobalt removal from wastewater using pine sawdust

    African Journals Online (AJOL)

    StudentLab

    2012-05-15

    May 15, 2012 ... was evaluated as an adsorbent in the treatment of wastewater containing cobalt ions. A two-level three ... showed adsorption capabilities for cobalt, and hence it could be an option in the quest to use waste to treat wastewater. ... using the Rushton turbine impellers for 30 min, and then separated by vacuum ...

  13. Cobalt 60 availability for radiation processing

    International Nuclear Information System (INIS)

    Fraser, F.M.

    1986-01-01

    In the last 20 years, the steady and significant growth in the application of radiation processing to industrial sterilization has been seen. The principal application of this technology is the sterilization of disposable medical products, food irradiation, the irradiation of personal care goods and so on. At present, more than 70 million curies of cobalt-60 supplied by Atomic Energy of Canada Ltd. have been used for gamma processing in these applications. This is estimated to be more than 80 % of the total cobalt-60 in service in the world. Commercial food irradiation has an exciting future, and as to the impact of food irradiation on the availability of cobalt-60 over the next ten years, two principal factors must be examined, namely, the anticipated demand for cobalt-60 in all radiation processing applications, and the supply of cobalt-60 to reliably meet the expected demand. As for the cobalt-60 in service today, 90 % is used for the sterilization of disposable medical products, 5 % for food irradiation, and 5 % for other application. The demand for up to 30 million curies of cobalt-60 is expected over the next 10 years. Today, it is estimated that over 150,000 tons of spices, fruit and fish are irradiated. The potential cobalt-60 production could exceed 110 million curies per year. Gamma processing application will demand nearly 50 million curies in 1990. (Kako, I.)

  14. Cobalt Complexes as Antiviral and Antibacterial Agents

    Directory of Open Access Journals (Sweden)

    Eddie L. Chang

    2010-05-01

    Full Text Available Metal ion complexes are playing an increasing role in the development of antimicrobials. We review here the antimicrobial properties of cobalt coordination complexes in oxidation state 3+. In addition to reviewing the cobalt complexes containing polydentate donor ligands, we also focus on the antimicrobial activity of the homoleptic [Co(NH36]3+ ion.

  15. Cobalt-chitosan: Magnetic and biodegradable heterogeneous ...

    Indian Academy of Sciences (India)

    Cobalt-chitosan: Magnetic and biodegradable catalyst. 1931. Table 3. Effects of the solvent, temperature and base on oxidation of phenylethyl alcohol using cobalt-chitosan.a. Entry. Solvent. Temperature. Base. Yield (%) b. 1. DMF. 100. K2CO3. 60. 2. DMF. 100. KOH. 60. 3. CH3CN. 80. K2CO3. 65. 4. H2O reflux. KOH. 10. 5.

  16. Cobalt Derivatives as Promising Therapeutic Agents

    Science.gov (United States)

    Heffern, Marie C.; Yamamoto, Natsuho; Holbrook, Robert J.; Eckermann, Amanda L.; Meade, Thomas J.

    2013-01-01

    Inorganic complexes are versatile platforms for the development of potent and selective pharmaceutical agents. Cobalt possesses a diverse array of properties that can be manipulated to yield promising drug candidates. Investigations into the mechanism of cobalt therapeutic agents can provide valuable insight into the physicochemical properties that can be harnessed for drug development. This review presents examples of bioactive cobalt complexes with special attention to their mechanisms of action. Specifically, cobalt complexes that elicit biological effects through protein inhibition, modification of drug activity, and bioreductive activation are discussed. Insights gained from these examples reveal features of cobalt that can be rationally tuned to produce therapeutics with high specificity and improved efficacy for the biomolecule or pathway of interest. PMID:23270779

  17. Cobalt sorption onto Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1985-06-01

    A laboratory study of cobalt-60 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that cobalt sorption is most strongly a function of pH. Over a pH range of 2 to 9, the distribution coefficient ranged from 2 to more than 10,000 mL/g. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence cobalt sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect on cobalt sorption. Ferrous ion, added to groundwater to simulate the condition of water at the bottom of the waste trenches, accounts for part of the decrease in cobalt sorption observed with trench waters. 17 refs., 3 figs., 4 tabs

  18. Structure of cobalt sulfate tetrahydrate

    International Nuclear Information System (INIS)

    Kellersohn, T.

    1992-01-01

    Cobalt(II) sulfate tetrahydrate-d 8 , CoSO 4 -4D 2 O, mineralogical name aplowite, monoclinic, P2 1 /n a = 5.952 (1), b = 13.576 (2), c = 7.908 (1) A. The title compound belongs to the rozenite group of minerals. The characteristic structural units are [Co 2 (SO 4 ) 2 (D 2 O) 8 ] heteropolyhedral clusters which are linked by hydrogen bonds of medium strength. One of the water molecules is very asymmetrically bonded, with one H (D) atom being involved in a long bifurcated hydrogen bond. (orig.)

  19. Influence of temperature, grain size and cobalt content on the hardness of WC-Co alloys

    CSIR Research Space (South Africa)

    Milman, YV

    1999-01-01

    Full Text Available , grain size and cobalt content on the hardness of WC?Co alloys Yu.V. Milman a, S. Luyckx b,c, IT Northrop d a Institute of Problems in Materials Science, Kiev, Ukraine b School of Process and Materials Engineering, University of the Witwatersrand...

  20. Cobalt-60 gamma radiation effects on degradation of pesticides used in stored rice and beans

    International Nuclear Information System (INIS)

    Groppo, Gerson A.

    1988-02-01

    The present work, carried out at CENA, an agriculture nuclear energy center - University of Sao Paulo - Brazil, investigates the Cobalt-60 gamma radiation effects on insecticides applied to stored rice and beans. The radiation dose applied - 200 Gy - to the stored rice and beans treated with insecticides was not sufficient to cause a noticeable chemical degradation through insect mortality. (author). 31 refs., 23 tabs

  1. Nickel acts as an adjuvant during cobalt sensitization

    DEFF Research Database (Denmark)

    Bonefeld, Charlotte Menne; Nielsen, Morten Milek; Vennegaard, Marie T.

    2015-01-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We...... investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found...... that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses...

  2. Cobalt-60 production in CANDU power reactors

    International Nuclear Information System (INIS)

    Slack, J.; Norton, J.L.; Malkoske, G.R.

    2003-01-01

    MDS Nordion has been supplying cobalt-60 sources to industry for industrial and medical purposes since 1946. These cobalt-60 sources are used in many market and product segments. The major application is in the health care industry where irradiators are used to sterilize single use medical products. These irradiators are designed and built by MDS Nordion and are used by manufacturers of surgical kits, gloves, gowns, drapes and other medical products. The irradiator is a large shielded room with a storage pool for the cobalt-60 sources. The medical products are circulated through the shielded room and exposed to the cobalt-60 sources. This treatment sterilizes the medical products which can then be shipped to hospitals for immediate use. Other applications for this irradiation technology include sanitisation of cosmetics, microbial reduction of pharmaceutical raw materials and food irradiation. The cobalt-60 sources are manufactured by MDS Nordion in their Cobalt Operations Facility in Kanata. More than 75,000 cobalt-60 sources for use in irradiators have been manufactured by MDS Nordion. The cobalt-60 sources are double encapsulated in stainless steel capsules, seal welded and helium leak tested. Each source may contain up to 14,000 curies. These sources are shipped to over 170 industrial irradiators around the world. This paper will focus on the MDS Nordion proprietary technology used to produce the cobalt-60 isotope in CANDU reactors. Almost 55 years ago MDS Nordion and Atomic Energy of Canada developed the process for manufacturing cobalt-60 at the Chalk River Labs, in Ontario, Canada. A cobalt-59 target was introduced into a research reactor where the cobalt-59 atom absorbed one neutron to become cobalt-60. Once the cobalt-60 material was removed from the research reactor it was encapsulated in stainless steel and seal welded using a Tungsten Inert Gas weld. The first cobalt-60 sources manufactured using material from the Chalk River Labs were used in cancer

  3. Cobalt-60 production in CANDU power reactors

    Energy Technology Data Exchange (ETDEWEB)

    Malkoske, G.R.; Norton, J.L. [MDS Nordion, Kanata, Ontario (Canada); Slack, J. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada)

    2002-07-01

    MDS Nordion has been supplying cobalt-60 sources to industry for industrial and medical purposes since 1946. These cobalt-60 sources are used in many market and product segments, but are primarily used to sterilize single-use medical products including; surgical kits, gloves, gowns, drapes, and cotton swabs. Other applications include sanitization of cosmetics, microbial reduction of pharmaceutical raw materials, and food irradiation. The technology for producing the cobalt-60 isotope was developed by MDS Nordion and Atomic Energy of Canada Limited (AECL) almost 55 years ago using research reactors at the AECL Chalk River Laboratories in Ontario, Canada. The first cobalt-60 source produced for medical applications was manufactured by MDS Nordion and used in cancer therapy. The benefits of cobalt-60 as applied to medical product manufacturing, were quickly realized and the demand for this radioisotope quickly grew. The same technology for producing cobalt-60 in research reactors was then designed and packaged such that it could be conveniently transferred to a utility/power reactor. In the early 1970's, in co-operation with Ontario Power Generation (formerly Ontario Hydro), bulk cobalt-60 production for industrial irradiation applications was initiated in the four Pickering A CANDU reactors. As the demand and acceptance of sterilization of medical products grew, MDS Nordion expanded its bulk supply by installing the proprietary Canadian technology for producing cobalt-60 in additional CANDU reactors. CANDU is unique among the power reactors of the world, being heavy water moderated and fuelled with natural uranium. They are also designed and supplied with stainless steel adjusters, the primary function of which is to shape the neutron flux to optimize reactor power and fuel bum-up, and to provide excess reactivity needed to overcome xenon-135 poisoning following a reduction of power. The reactor is designed to develop full power output with all of the adjuster

  4. Cobalt-60 production in CANDU power reactors

    International Nuclear Information System (INIS)

    Malkoske, G.R.; Norton, J.L.; Slack, J.

    2002-01-01

    MDS Nordion has been supplying cobalt-60 sources to industry for industrial and medical purposes since 1946. These cobalt-60 sources are used in many market and product segments, but are primarily used to sterilize single-use medical products including; surgical kits, gloves, gowns, drapes, and cotton swabs. Other applications include sanitization of cosmetics, microbial reduction of pharmaceutical raw materials, and food irradiation. The technology for producing the cobalt-60 isotope was developed by MDS Nordion and Atomic Energy of Canada Limited (AECL) almost 55 years ago using research reactors at the AECL Chalk River Laboratories in Ontario, Canada. The first cobalt-60 source produced for medical applications was manufactured by MDS Nordion and used in cancer therapy. The benefits of cobalt-60 as applied to medical product manufacturing, were quickly realized and the demand for this radioisotope quickly grew. The same technology for producing cobalt-60 in research reactors was then designed and packaged such that it could be conveniently transferred to a utility/power reactor. In the early 1970's, in co-operation with Ontario Power Generation (formerly Ontario Hydro), bulk cobalt-60 production for industrial irradiation applications was initiated in the four Pickering A CANDU reactors. As the demand and acceptance of sterilization of medical products grew, MDS Nordion expanded its bulk supply by installing the proprietary Canadian technology for producing cobalt-60 in additional CANDU reactors. CANDU is unique among the power reactors of the world, being heavy water moderated and fuelled with natural uranium. They are also designed and supplied with stainless steel adjusters, the primary function of which is to shape the neutron flux to optimize reactor power and fuel bum-up, and to provide excess reactivity needed to overcome xenon-135 poisoning following a reduction of power. The reactor is designed to develop full power output with all of the adjuster

  5. Mechanical properties of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2007-01-01

    Full Text Available Background/Aim. Metal-ceramic bond strength and alloys' elastic modulus clearly determine the potential of alloy application, because the ceramic integrity during mastication depends on these two characteristics. The aim of this study was to evaluate metal-ceramic bond strength and elastic modulus of cobalt-chromium alloys in making porcelainfused- to-metal restorations, regarding the application of the most frequent nickel-chromium alloy. Methods. The research was performed as an experimental study. Six metalceramic samples were made from nickel-chromium alloy (Wiron 99 and cobalt-chromium alloy (Wirobond C, according to the manufactures manuals and instructions from ISO 9693: 1996. Three-point bending test was performed up to the ceramic fracture. The fracture load was measured on an universal testing machine (Zwick, type 1464, with cross-head speed of 0,05mm/min. Results. The results of this study confirmed the significant differences between the metal-ceramic bond strength (p < 0.01 and elastic modulus (p < 0.001 of nickel-chromium and cobalt-chromium alloys, where cobalt-chromium alloys showed higher values for both tested parameters. Conclusion. Cobalt-chromium metal-ceramic alloys can successfully replace nickel-chromium alloys, especially for fabrication of long-span metal-ceramic bridges due to the great flexural strength.

  6. Preparation of electrodeposited cobalt nanowires

    Directory of Open Access Journals (Sweden)

    Valeska da Rocha Caffarena

    2006-06-01

    Full Text Available Nanostructured magnetic materials have great interest because of their applications in high-density magnetic information storage and for magnetic sensors. The electrodeposition of materials into porous alumina arrays is a suitable technique to produce nanomaterials, since highly ordered uniform nanomaterials can be obtained simply and cheaply. In this work, template-assisted Co nanowire arrays were prepared by electrodeposition into nanometer-sized pores of an alumite film using a two-electrode electrochemical cell. The Co nanowires were electrodeposited from a solution of 400 g/L of CoSO4.7H2O and 40 g/L of H3BO3. The morphology of the samples was investigated by means of TEM and AFM. The structural characteristic of the samples was examined using XRD, EDX and FTIR, which confirm the cobalt nanowire formation.

  7. Cobalt-60 control in Ontario Hydro reactors

    International Nuclear Information System (INIS)

    Lacy, C.S.

    1988-01-01

    This paper discusses the impact of specifying reduced Cobalt-59 in the primary heat transport circuit materials of construction on the radiation fields developed around the primary circuit. An eight-fold reduction in steam generator radiation fields due to Cobalt-60 has been observed for two identical sets of reactors, one with and one without Cobalt-59 control. The comparison is between eight reactors at the Pickering Nuclear Generating Station (PNGS). Units 5 to 8 (PNGS-B) are identical to Units 1 to 4 (PNGS-A) except that PNGS-B has reduced impurity Cobalt-59 in the alloys of construction and a reduced use of stellite. The effects of chemistry control are also discussed

  8. Controlled cobalt doping in biogenic magnetite nanoparticles.

    Science.gov (United States)

    Byrne, J M; Coker, V S; Moise, S; Wincott, P L; Vaughan, D J; Tuna, F; Arenholz, E; van der Laan, G; Pattrick, R A D; Lloyd, J R; Telling, N D

    2013-06-06

    Cobalt-doped magnetite (CoxFe3 -xO4) nanoparticles have been produced through the microbial reduction of cobalt-iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe(2+) site with Co(2+), with up to 17 per cent Co substituted into tetrahedral sites.

  9. Transport properties of cobalt at low temperatures

    DEFF Research Database (Denmark)

    Radharkishna, P.; Nielsen, Mourits

    1965-01-01

    Measurements are made of electrical resistivity, absolute thermoelectric power, and thermal conductivity of polycrystalline cobalt between 1.2 and 6 K; results are discussed on basis of inter-electronic scattering.......Measurements are made of electrical resistivity, absolute thermoelectric power, and thermal conductivity of polycrystalline cobalt between 1.2 and 6 K; results are discussed on basis of inter-electronic scattering....

  10. [Are the cobalt hip prosthesis dangerous?].

    Science.gov (United States)

    Mistretta, Virginie; Kurth, William; Charlier, Corinne

    The placement of a hip prosthesis is one of the most common orthopedic surgical procedures. Some implants contain metal and are therefore capable of releasing metal particles like cobalt in patients who wear metal prostheses. Cobalt can be responsible of local toxicity (including metallosis, hypersensitivity reaction, and benign tumor) or systemic toxicity (including cardiomyopathy, polycythemia, hypothyroidism, and neurological disorders). To monitor potential toxicity of metal hip prostheses, an annual monitoring of patients implanted is recommended and includes clinical examination, radiological examination and blood cobalt determination. The cobalt concentration in blood allows to estimate the risk of toxicity and to evaluate the performance of the implant. The currently recommended threshold value is equal to 7 µg of cobalt per liter of blood. Our study, conducted on 251 patients over a period of 4 years, has shown that the cobalt concentration average was 2.51 µg/l in blood, with 51 patients having a cobaltemia higher than the threshold of 7 µg/l. © 2016 médecine/sciences – Inserm.

  11. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Science.gov (United States)

    2010-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts. ...

  12. Nickel acts as an adjuvant during cobalt sensitization.

    Science.gov (United States)

    Bonefeld, Charlotte Menné; Nielsen, Morten Milek; Vennegaard, Marie T; Johansen, Jeanne Duus; Geisler, Carsten; Thyssen, Jacob P

    2015-03-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses in the draining lymph nodes compared to mice sensitized with cobalt alone. In contrast, the presence of cobalt during nickel sensitization only induced an increased CD8(+) T cell proliferation during challenge to nickel. Thus, the presence of nickel during cobalt sensitization potentiated the challenge response against cobalt more than the presence of cobalt during sensitization to nickel affected the challenge response against nickel. Taken together, our study demonstrates that sensitization with a mixture of nickel and cobalt leads to an increased immune response to both nickel and cobalt, especially to cobalt, and furthermore that the adjuvant effect appears to correlate with the inflammatory properties of the allergen. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil

    2010-01-01

    Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure.......Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure....

  14. A novel method to synthesize cobalt oxide (Co3O4) nanowires from cobalt (Co) nanobowls

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A novel method suitable for the synthesis of the cobalt oxide (Co3O4) nanowires at targeted regions is presented in this report. Cobalt (Co) nanobowls synthesized by colloidal crystal directed assembly were transformed into Co3O4 nanowires by a simple heat treatment process. Co nanobowls exhibited...

  15. Synthesis of new cobalt aluminophosphate framework by opening a cobalt methylphosphonate layered material

    Czech Academy of Sciences Publication Activity Database

    Zaarour, M.; Pérez, O.; Boullay, P.; Martens, J.; Mihailova, B.; Karaghiosoff, K.; Palatinus, Lukáš; Mintova, S.

    2017-01-01

    Roč. 19, č. 34 (2017), s. 5100-5105 ISSN 1466-8033 Institutional support: RVO:68378271 Keywords : cobalt aluminophosphate * cobalt methylphosphonate * layered materials * crystallic structure * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.474, year: 2016

  16. Biological responses of isolated macrophages to cobalt metal and tungsten carbide-cobalt powders.

    Science.gov (United States)

    Lison, D; Lauwerys, R

    1991-10-01

    A previous study from this laboratory, using morphological and biochemical (LDH release) parameters, has shown that tungsten carbide-cobalt dust exhibits a greater cytotoxicity toward isolated macrophages than cobalt metal powder alone. The present study extends this comparison by examining additional biological parameters. Glucose uptake and superoxide anion production by isolated macrophages were significantly more depressed by the tungsten carbide-cobalt mixture (WC-Co) than by cobalt alone (Co) while pure tungsten carbide (WC) had no effect or even stimulated the cells. For glucose-6-phosphate dehydrogenase and cell-associated plasminogen activator (PA) activities, no difference between Co and WC-Co dusts was observed. These observations add further evidence to our previous findings regarding the different biological reactivity of cobalt metal alone or mixed with tungsten carbide.

  17. Long-Term Intermittent Hypoxia Elevates Cobalt Levels in the Brain and Injures White Matter in Adult Mice

    Science.gov (United States)

    Veasey, Sigrid C.; Lear, Jessica; Zhu, Yan; Grinspan, Judith B.; Hare, Dominic J.; Wang, SiHe; Bunch, Dustin; Doble, Philip A.; Robinson, Stephen R.

    2013-01-01

    Study Objectives: Exposure to the variable oxygenation patterns in obstructive sleep apnea (OSA) causes oxidative stress within the brain. We hypothesized that this stress is associated with increased levels of redox-active metals and white matter injury. Design: Participants were randomly allocated to a control or experimental group (single independent variable). Setting: University animal house. Participants: Adult male C57BL/6J mice. Interventions: To model OSA, mice were exposed to long-term intermittent hypoxia (LTIH) for 10 hours/day for 8 weeks or sham intermittent hypoxia (SIH). Measurements and Results: Laser ablation-inductively coupled plasma-mass spectrometry was used to quantitatively map the distribution of the trace elements cobalt, copper, iron, and zinc in forebrain sections. Control mice contained 62 ± 7 ng cobalt/g wet weight, whereas LTIH mice contained 5600 ± 600 ng cobalt/g wet weight (P Cobalt was concentrated within white matter regions of the brain, including the corpus callosum. Compared to that of control mice, the corpus callosum of LTIH mice had significantly more endoplasmic reticulum stress, fewer myelin-associated proteins, disorganized myelin sheaths, and more degenerated axon profiles. Because cobalt is an essential component of vitamin B12, serum methylmalonic acid (MMA) levels were measured. LTIH mice had low MMA levels (P cobalt, predominantly in the white matter. The increased cobalt is associated with endoplasmic reticulum stress, myelin loss, and axonal injury. Low plasma methylmalonic acid levels are associated with white matter injury in long-term intermittent hypoxia and possibly in obstructive sleep apnea. Citation: Veasey SC; Lear J; Zhu Y; Grinspan JB; Hare DJ; Wang S; Bunch D; Doble PA; Robinson SR. Long-term intermittent hypoxia elevates cobalt levels in the brain and injures white matter in adult mice. SLEEP 2013;36(10):1471-1481. PMID:24082306

  18. Synthesis of Samarium Cobalt Nanoblades

    Energy Technology Data Exchange (ETDEWEB)

    Darren M. Steele

    2010-08-25

    As new portable particle acceleration technologies become feasible the need for small high performance permanent magnets becomes critical. With particle accelerating cavities of a few microns, the photonic crystal fiber (PCF) candidate demands magnets of comparable size. To address this need, samarium cobalt (SmCo) nanoblades were attempted to be synthesized using the polyol process. Since it is preferable to have blades of 1-2 {micro}m in length, key parameters affecting size and morphology including method of stirring, reaction temperature, reaction time and addition of hydroxide were examined. Nanoparticles consisting of 70-200 nm spherical clusters with a 3-5 nm polyvinylpyrrolidone (PVP) coating were synthesized at 285 C and found to be ferromagnetic. Nanoblades of 25nm in length were observed at the surface of the nanoclusters and appeared to suggest agglomeration was occurring even with PVP employed. Morphology and size were characterized using a transmission electron microscope (TEM). Powder X-Ray Diffraction (XRD) analysis was conducted to determine composition but no supportive evidence for any particular SmCo phase has yet been observed.

  19. IN SITU AND POST REACTION COBALT-INCORPORATION INTO ...

    African Journals Online (AJOL)

    bridged silica materials decreased with increasing loading of APTS as well as after cobalt incorporation. Thermogravimetric analysis and Raman spectroscopy show that the surfactant is removed by solvent extraction. Cobalt ion incorporation is ...

  20. Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

    Science.gov (United States)

    Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

    2014-01-01

    A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established. PMID:24701183

  1. Cobalt: A vital element in the aircraft engine industry

    Science.gov (United States)

    Stephens, J. R.

    1981-01-01

    Recent trends in the United States consumption of cobalt indicate that superalloys for aircraft engine manufacture require increasing amounts of this strategic element. Superalloys consume a lion's share of total U.S. cobalt usage which was about 16 million pounds in 1980. In excess of 90 percent of the cobalt used in this country was imported, principally from the African countries of Zaire and Zambia. Early studies on the roles of cobalt as an alloying element in high temperature alloys concentrated on the simple Ni-Cr and Nimonic alloy series. The role of cobalt in current complex nickel base superalloys is not well defined and indeed, the need for the high concentration of cobalt in widely used nickel base superalloys is not firmly established. The current cobalt situation is reviewed as it applies to superalloys and the opportunities for research to reduce the consumption of cobalt in the aircraft engine industry are described.

  2. Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

    Directory of Open Access Journals (Sweden)

    Grzegorz Kowalski

    2014-01-01

    Full Text Available A study of polyaniline (PANI doping with various cobalt compounds, that is, cobalt(II chloride, cobalt(II acetate, and cobalt(II salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established.

  3. Association between cobalt allergy and dermatitis caused by leather articles

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus

    2015-01-01

    BACKGROUND: Cobalt is a strong skin sensitizer and a prevalent contact allergen. Recent studies have recognized exposure to leather articles as a potential cause of cobalt allergy. OBJECTIVES: To examine the association between contact allergy to cobalt and a history of dermatitis resulting from....... CONCLUSIONS: Our study suggests a positive association between cobalt allergy and a history of dermatitis caused by non-occupational exposure to leather articles....

  4. Manipulating radicals: Using cobalt to steer radical reactions

    OpenAIRE

    Chirilă, A.

    2017-01-01

    This thesis describes research aimed at understanding and exploiting metallo-radical reactivity and explores reactions mediated by square planar, low-spin cobalt(II) complexes. A primary goal was to uncover novel reactivity of discrete cobalt(III)-bound carbene radicals generated upon reaction of the cobalt(II) catalysts with carbene precursors. Another important goal was to replace cobalt(II)-porphyrin catalysts with cheaper and easier to prepare metallo-radical analogues. Therefore the cata...

  5. The physiological effect of cobalt on watermelon cultivation

    International Nuclear Information System (INIS)

    Yao Naihua; Jin Yafang; Sun Yaochen; Huang Yiming

    1993-01-01

    Cobalt has essential physiological action on both animals and plants. For the latter it can raise plant's nitrogen-fixing ability and saccharine content. Spray of cobalt mixed with other nutritive elements can improve the germinatit of seeds and the yield of fruit. For specifying the nutritive function of cobalt upon watermelon, isotope 60 Co was mixed into a complex leaf nutritive aqua and the regularity of transferring and absorbing cobalt in the watermelon's body was investigated

  6. Relaxation resistance of heat resisting alloys with cobalt

    International Nuclear Information System (INIS)

    Borzdyka, A.M.

    1977-01-01

    Relaxation resistance of refractory nickel-chromium alloys containing 5 to 14 % cobalt is under study. The tests involve the use of circular samples at 800 deg to 850 deg C. It is shown that an alloy containing 14% cobalt possesses the best relaxation resistance exceeding that of nickel-chromium alloys without any cobalt by a factor of 1.5 to 2. The relaxation resistance of an alloy with 5% cobalt can be increased by hardening at repeated loading

  7. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    Science.gov (United States)

    Adzic, Radoslav [East Setauket, NY; Huang, Tao [Manorville, NY

    2009-12-15

    The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

  8. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining a...

  9. Feasibility Study for Cobalt Bundle Loading to CANDU Reactor Core

    International Nuclear Information System (INIS)

    Park, Donghwan; Kim, Youngae; Kim, Sungmin

    2016-01-01

    CANDU units are generally used to produce cobalt-60 at Bruce and Point Lepreau in Canada and Embalse in Argentina. China has started production of cobalt-60 using its CANDU 6 Qinshan Phase III nuclear power plant in 2009. For cobalt-60 production, the reactor’s full complement of stainless steel adjusters is replaced with neutronically equivalent cobalt-59 adjusters, which are essentially invisible to reactor operation. With its very high neutron flux and optimized fuel burn-up, the CANDU has a very high cobalt-60 production rate in a relatively short time. This makes CANDU an excellent vehicle for bulk cobalt-60 production. Several studies have been performed to produce cobalt-60 using adjuster rod at Wolsong nuclear power plant. This study proposed new concept for producing cobalt-60 and performed the feasibility study. Bundle typed cobalt loading concept is proposed and evaluated the feasibility to fuel management without physics and system design change. The requirement to load cobalt bundle to the core was considered and several channels are nominated. The production of cobalt-60 source is very depend on the flux level and burnup directly. But the neutron absorption characteristic of cobalt bundle is too high, so optimizing design study is needed in the future

  10. Assessment of cobalt levels in wastewater, soil and vegetable ...

    African Journals Online (AJOL)

    User

    Cobalt concentrations in this study were higher than maximum contaminant levels set by Standard. Organizations such as WHO and FAO in wastewater while below their limits in vegetables. Key words: Cobalt level, Kubanni River, soil, vegetable, wastewater. INTRODUCTION. Cobalt is beneficial to human because it is part ...

  11. Structural and magnetic properties of cobalt-doped iron oxide nanoparticles prepared by solution combustion method for biomedical applications

    Directory of Open Access Journals (Sweden)

    Venkatesan K

    2015-10-01

    Full Text Available Kaliyamoorthy Venkatesan,1 Dhanakotti Rajan Babu,1 Mane Prabhu Kavya Bai,2 Ravi Supriya,2 Radhakrishnan Vidya,2 Saminathan Madeswaran,1 Pandurangan Anandan,3 Mukannan Arivanandhan,3 Yasuhiro Hayakawa3 1School of Advanced Sciences, 2School of Bio Sciences and Technology, VIT University, Vellore, Tamil Nadu, India; 3Research Institute of Electronics, Shizuoka University, Hamamatsu, Japan Abstract: Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4 magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311 of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed. Keywords: cytotoxicity, HR-TEM, magnetic nanoparticles, VSM 

  12. Controlled cobalt doping in biogenic magnetite nanoparticles

    Science.gov (United States)

    Byrne, J. M.; Coker, V. S.; Moise, S.; Wincott, P. L.; Vaughan, D. J.; Tuna, F.; Arenholz, E.; van der Laan, G.; Pattrick, R. A. D.; Lloyd, J. R.; Telling, N. D.

    2013-01-01

    Cobalt-doped magnetite (CoxFe3 −xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites. PMID:23594814

  13. Perfluorinated cobalt phthalocyanine effectively catalyzes water electrooxidation

    KAUST Repository

    Morlanes, Natalia Sanchez

    2014-12-08

    Efficient electrocatalysis of water oxidation under mild conditions at neutral pH was achieved by a fluorinated cobalt phthalocyanine immobilized on fluorine-doped tin oxide (FTO) surfaces with an onset potential at 1.7 V vs. RHE. Spectroscopic, electrochemical, and inhibition studies indicate that phthalocyanine molecular species are the operational active sites. Neither free cobalt ions nor heterogeneous cobalt oxide particles or films were observed. During long-term controlled-potential electrolysis at 2 V vs. RHE (phosphate buffer, pH 7), electrocatalytic water oxidation was sustained for at least 8 h (TON ≈ 1.0 × 105), producing about 4 μmol O2 h-1 cm-2 with a turnover frequency (TOF) of about 3.6 s-1 and no measurable catalyst degradation.

  14. Rapid phase synthesis of nanocrystalline cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugavel, T., E-mail: shanmugavelnano@gmail.com [Department of Physics, Paavai Engineering College, Namakkal -637018 (India); Raj, S. Gokul [Department of Physics, Vel Tech University, Avadi, Chennai - 600 062 (India); Rajarajan, G. [Department of Physics, Mahendra Engineering College, Mallasamudram -637503 (India); Kumar, G. Ramesh [Department of Physics, University College of Engineering, Anna University Chennai, Arni- 632317 (India)

    2014-04-24

    Synthesis of single phase nanocrystalline Cobalt Ferrite (CoFe{sub 2}O{sub 4}) was achieved by single step autocombustion technique with the use of citric acid as a chelating agent in mono proportion with metal. Specimens prepared with this method showed significantly higher initial permeability's than with the conventional process. Single phase nanocrystalline cobalt ferrites were formed at very low temperature. Surface morphology identification were carried out by transmission electron microscopy (TEM) analysis. The average grain size and density at low temperature increased gradually with increasing the temperature. The single phase formation is confirmed through powder X-ray diffraction analysis. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors. Temperature dependent magnetization results showed improved behavior for the nanocrystalline form of cobalt ferrite when compared to the bulk nature of materials synthesized by other methods.

  15. Solubility of cobalt in primary circuit solutions

    International Nuclear Information System (INIS)

    Lambert, I.; Joyer, F.

    1992-01-01

    The solubility of cobalt ferrite (CoFe 2 O 4 ) was measured in PWR primary circuit conditions, in the temperature range 250-350 deg C, and the results were compared with the ones obtained on magnetite and nickel ferrite. As in the former cases, it was found that, in the prevailing primary circuit conditions, the solubility of the cobalt ferrite was minimum at temperatures around 300 deg C, for cobalt as well as for iron. The equilibrium iron concentration is significantly lower than in the case of magnetite. The results are discussed in relation with the POTHY code, based only on thermodynamic laws and data, used for the prediction of the primary circuit chemistry

  16. Radioactive cobalt removal from Salem liquid radwaste with cobalt selective media

    International Nuclear Information System (INIS)

    Maza R.; Wilson, J.A.; Hetherington, R.

    1995-01-01

    This paper reports results of benchtop tests using ion exchange material to selectively remove radioactive cobalt from high conductivity liquid radwaste at the Salem Nuclear Generating Station. The purpose of this test program is to reduce the number of curies in liquid releases without increasing the solid waste volume. These tests have identified two cobalt selective materials that together remove radioactive cobalt more effectively than the single component currently used. All test materials were preconditioned by conversion to the divalent calcium or sulfate form to simulate chemically exhausted media

  17. Radiation induced ligand loss from cobalt complexes

    International Nuclear Information System (INIS)

    Funston, A. M.; McFadyen, W.D.; Tregloan, P.A.

    2000-01-01

    Full text: Due to the rapid nature of ligand dissociation from cobalt(II) complexes the study of the rate of ligand dissociation necessitates the use of a technique such as pulse radiolysis. This allows the rapid reduction of the corresponding cobalt(III) complex by a reducing radical, such as the aquated electron, to form the cobalt(II) complex. However, to date, no systematic study of either the mechanism of reduction or the influence of the electronic structure on the rate of ligand dissociation has been carried out. In order to understand these processes more fully the mechanism of reduction of a range of related cobalt(III) complexes by the aquated electron and the subsequent rate of ligand dissociation from the resulting cobalt(II) complexes is being investigated. It has been found that a number of processes are observed following the initial rapid reaction of the cobalt(III) complex with the aquated electron. Ultimately ligand loss is observed. Depending upon the complex, the initial processes observed may include the formation of coordinated radicals and electron transfer within the complex. For complexes containing aromatic ligands such as 2,2'-bipyridine, 1,10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine the formation of a coordinated radical is observed as the initial reduction step. The kinetics of ligand dissociation of these complexes has been determined. The loss of monodentate ligands is fast and has been indistinguishable from the reduction processes when aromatic ligands are also present in the complex. However, for diamine chelates and diimine chelates spectra of the transient species can be resolved

  18. Cobalt-free nickel-base superalloys

    International Nuclear Information System (INIS)

    Koizumi, Yutaka; Yamazaki, Michio; Harada, Hiroshi

    1979-01-01

    Cobalt-free nickel-base cast superalloys have been developed. Cobalt is considered to be a beneficial element to strengthen the alloys but should be eliminated in alloys to be used for direct cycle helium turbine driven by helium gas from HTGR (high temp. gas reactor). The elimination of cobalt is required to avoid the formation of radioactive 60 Co from the debris or scales of the alloys. Cobalt-free alloys are also desirable from another viewpoint, i.e. recently the shortage of the element has become a serious problem in industry. Cobalt-free Mar-M200 type alloys modified by the additions of 0.15 - 0.2 wt% B and 1 - 1.5 wt% Hf were found to have a creep rupture strength superior or comparable to that of the original Mar-M200 alloy bearing cobalt. The ductility in tensile test at 800 0 C, as cast or after prolonged heating at 900 0 C (the tensile test was done without removing the surface layer affected by the heating), was also improved by the additions of 0.15 - 0.2% B and 1 - 1.5% Hf. The morphology of grain boundaries became intricated by the additions of 0.15 - 0.2% B and 1 - 1.5% Hf, to such a degree that one can hardly distinguish grain boundaries by microscopes. The change in the grain boundary morphology was considered, as suggested previously by one of the authors (M.Y.), to be the reason for the improvements in the creep rupture strength and tensile ductility. (author)

  19. Peroxidase-like activity of nanocrystalline cobalt selenide and its application for uric acid detection

    Directory of Open Access Journals (Sweden)

    Zhuang QQ

    2017-04-01

    Full Text Available Quan-Quan Zhuang,1 Zhi-Hang Lin,1 Yan-Cheng Jiang,1 Hao-Hua Deng,2 Shao-Bin He,1,3 Li-Ting Su,4 Xiao-Qiong Shi,2 Wei Chen2 1Department of Pharmacy, Affiliated Quanzhou First Hospital of Fujian Medical University, Quanzhou, 2Department of Pharmaceutical Analysis, School of Pharmacy, Fujian Medical University, Fuzhou, 3Department of Pharmacy, Quanzhou Infectious Disease Hospital, 4Department of Pharmaceutical Analysis, Quanzhou Medical College, Quanzhou, People’s Republic of China Abstract: Dendrite-like cobalt selenide nanostructures were synthesized from cobalt and selenium powder precursors by a solvothermal method in anhydrous ethylenediamine. The as-prepared nanocrystalline cobalt selenide was found to possess peroxidase-like activity that could catalyze the reaction of peroxidase substrates in the presence of H2O2. A spectrophotometric method for uric acid (UA determination was developed based on the nanocrystalline cobalt selenide-catalyzed coupling reaction between N-ethyl-N-(3-sulfopropyl-3-methylaniline sodium salt and 4-aminoantipyrine (4-AAP in the presence of H2O2. Under optimum conditions, the absorbance was proportional to the concentration of UA over the range of 2.0–40 µM with a detection limit of 0.5 µM. The applicability of the proposed method has been validated by determination of UA in human serum samples with satisfactory results. Keywords: enzyme mimics, cobalt selenide, peroxidase-like activity, uric acid, human serum

  20. Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Partha P. Goswami

    2013-01-01

    Full Text Available Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques.

  1. EXAFS Determination of the Structure of Cobalt in Carbon-Supported Cobalt and Cobalt-Molybdenum Sulfide Hydrodesulfurization Catalysts.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Bouwens, S.M.A.M.; Veen, J.A.R. van; Beer, V.H.J. de; Prins, R.

    1991-01-01

    The structure of the cobalt present in carbon-supported Co and Co-Mo sulfide catalysts was studied by means of X-ray absorption spectroscopy at the Co K-edge and by X-ray photoelectron spectroscopy (XPS). Thiophene hydrodesulfurization activities were used to measure the catalytic properties of

  2. Effect of cobalt on the primary productivity of Spirulina platensis

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R.M.; Panigrahi, S.; Azeez, P.A.

    1987-10-01

    Cobalt, a micronutrient for biological organisms, is a metal of wide use. Main sources of Co to the environment are combustion of fossil fuels, smelters, cobalt processing facilities, sewage and industrial wastes. Atomic power plants and nuclear weapon detonations form an important source of radioisotopes of this metal to the environment. Cobalt has been included in the 14 toxic trace elements of critical importance from the point of view of environmental pollution and health hazards. Cobalt deficiency leads to diseases like stunted growth. At toxic level, Co inhibits heme biosynthesis and enzyme activities. The present study reports the effect of cobalt on biomass productivity of blue-green alga Spirulina platensis.

  3. Establishing human heart chromium, cobalt and vanadium concentrations by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Day, Patrick L; Eckdahl, Steven J; Maleszewski, Joseph J; Wright, Thomas C; Murray, David L

    2017-05-01

    Chromium, cobalt, and vanadium are used in metallic joint prosthesis. Case studies have associated elevated heart tissue cobalt concentrations with myocardial injury. To document the long term heart metal ion concentrations, a validated inductively coupled plasma mass spectroscopy (ICP-MS) method was needed. The method utilized a closed-vessel microwave digestion system to digest the samples. An ICP-MS method utilizing Universal Cell Technology was used to determine our target analyte concentrations. Accuracy was verified using reference materials. Precision, sensitivity, recovery and linearity studies were performed. This method was used to establish a reference range for a non-implant containing cohort of 80 autopsy human heart tissues RESULTS: This method demonstrated an analytic measurement range of 0.5-100ng/mL for each element. Accuracy was within ±10% of target value for each element. Within-run precision for each element was below 20% CV. The chromium, vanadium and cobalt concentrations (mean±SD) were 0.1523±0.2157μg/g, 0.0094±0.0211μg/g and 0.1039±0.1305μg/g respectively in 80 non-implant containing human heart tissue samples. This method provides acceptable recovery of the chromium, cobalt and vanadium in heart tissue; allowing assessment of the effects of metallic joint prosthesis on myocardial health. Copyright © 2017 Elsevier GmbH. All rights reserved.

  4. Toxicity and bioactivity of cobalt nanoparticles on the monocytes.

    Science.gov (United States)

    Liu, Ya-ke; Ye, Jun; Han, Qing-lin; Tao, Ran; Liu, Fan; Wang, Wei

    2015-05-01

    To explore the toxicity and biological activity of cobalt nanoparticles on the osteoclasts. Analyze the relationship between cobalt nanoparticles and osteolysis. Monocyte-macrophages (RAW 264.7) was cultured in vitro, osteoclast-like cells were induced by lipopolysaccharides (LPS). After RAW 264.7 was induced for 24 h, Methyl Thiazolium Tetrazolium (MTT) biological toxicity test of osteoclast-like cell was preceded using Cobalt nanoparticles (set 4 concentrations: 10, 20, 50, 100 μM) and cobalt chloride (set 4 concentrations: 10, 20, 50, 100 μM) at 2, 4, 8, 24 and 48 h respectively. The relative expression of mRNA of CA II and Cat K after RAW 264.7 induction was determined by Q-PCR. mRNA relative expression of CA II, Cat K were reduced at multiple concentrations both cobalt nanoparticles and cobalt chloride, and was time and concentration dependent, cobalt nanoparticles are more significant than cobalt chloride group. But when the cobalt nanoparticles concentration is in 10-50 μM, the mRNA relative expression of CA II, Cat K increased. Cobalt nanoparticles have biological toxicity. At multiple concentrations, the differentiation and proliferation of osteoclasts was inhibited, but when the concentration of cobalt nanoparticles is in 10-50 μM, it has been strengthened. © 2015 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.

  5. OXYGEN-1S AND COBALT-2P X-RAY ABSORPTION OF COBALT OXIDES

    NARCIS (Netherlands)

    DEGROOT, FMF; ABBATE, M; VANELP, J; SAWATZKY, GA; MA, YJ; CHEN, CT; SETTE, F

    1993-01-01

    The oxygen ls and cobalt 2p x-ray absorption spectra of CoO, Li-doped CoO and LiCoO2 have been measured with 0.1 eV resolution. The cobalt 2p spectra are analysed with a ligand-field multiplet model and the inclusion of charge-transfer effects is discussed. The oxygen ls spectra are interpreted as

  6. Cobalt reduction of NSSS valve hardfacings for ALARA

    International Nuclear Information System (INIS)

    Kim, Joo Hak; Lee, Sang Sub

    1994-07-01

    This report informs NSSS designer that replacement of materials is one of the major means of ALARA implementation, and describes that NSSS valves with high-cobalt hardfacing are significant contributors to post-shutdown radiation fields caused by activation of cobalt-59 to cobalt-60. Generic procedures for implementing cobalt reduction programs for valves are presented. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. The nuclear safety issues involved with changing valve hardfacing materials are discussed. The common methods used to deposit hardfacing materials are described together with an explanation of the wear measurements. Wear resistance, corrosion resistance, friction coefficient, and mechanical properties of candidate hardfacing alloys are given. World-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The use of low-cobalt or cobalt-free alloys in other nuclear plant components is described. 17 figs., 38 tabs., 18 refs. (Author)

  7. Mechanochemical Preparation of Cobalt Nanoparticles through a Novel Intramolecular Reaction in Cobalt(II Complexes

    Directory of Open Access Journals (Sweden)

    Seyed Abolghasem Kahani

    2015-01-01

    Full Text Available A novel solid state reaction involving a series of cobalt(II hydrazine-azides has been used to prepare metallic cobalt nanoparticles. The reactions of [Co(N2H4(N32], [Co(N2H42(N32], and [Co(N2H4(N3Cl]·H2O via NaOH, KOH as reactants were carried out in the solid state. These complexes undergo an intramolecular two-electron oxidation-reduction reaction at room temperature, producing metallic cobalt nanoparticles (Co1–Co6. The aforementioned complexes contain cobalt(II that is an oxidizing agent and also hydrazine ligand as a reducing agent. Other products produced include sodium azide and ammonia gas. The cobalt metal nanoparticles were characterized using X-ray powder diffraction (XRD, scanning electron microscopy (SEM, and vibrating sample magnetometer (VSM. The synthesized cobalt nanoparticles have similar morphologies; however, their particle size distributions are different.

  8. Cobalt (II) supported on ethylenediamine-functionalized ...

    Indian Academy of Sciences (India)

    Ethylenediamine-functionalized nanocellulose complexed with cobalt(II) was found to be a highly efficient heterogeneous catalyst for the room temperature aerobic oxidation of various types of primary and secondary benzylic alcohols into their corresponding aldehydes and ketones, respectively. The catalyst showed no ...

  9. Nano cobalt oxides for photocatalytic hydrogen production

    KAUST Repository

    Mangrulkar, Priti A.

    2012-07-01

    Nano structured metal oxides including TiO 2, Co 3O 4 and Fe 3O 4 have been synthesized and evaluated for their photocatalytic activity for hydrogen generation. The photocatalytic activity of nano cobalt oxide was then compared with two other nano structured metal oxides namely TiO 2 and Fe 3O 4. The synthesized nano cobalt oxide was characterized thoroughly with respect to EDX and TEM. The yield of hydrogen was observed to be 900, 2000 and 8275 mmol h -1 g -1 of photocatalyst for TiO 2, Co 3O 4 and Fe 3O 4 respectively under visible light. It was observed that the hydrogen yield in case of nano cobalt oxide was more than twice to that of TiO 2 and the hydrogen yield of nano Fe 3O 4 was nearly four times as compared to nano Co 3O 4. The influence of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  10. Spinel cobalt ferrite by complexometric synthesis

    NARCIS (Netherlands)

    Pham Duc Thang, P.D.T.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2005-01-01

    Magnetic fine particles of cobalt ferrite (CoFe2O4) have been synthesized using complexometric method in which ethylene diamine tetra acetic acid C10H16N2O8 (EDTA) acts as a complexing agent. The crystallographic structure, microstructure and magnetic properties of the synthesized powder were

  11. Water Adsorption on Free Cobalt Cluster Cations

    NARCIS (Netherlands)

    Kiawi, Denis M.; Bakker, Joost M.; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L. B. F. M.

    2015-01-01

    Cationic cobalt clusters complexed with water Con+–H2O (n = 6–20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200–1700 cm–1 spectral range. All spectra exhibit a resonance close to the 1595 cm–1 frequency of the free

  12. Water adsorption on free cobalt cluster cations

    NARCIS (Netherlands)

    Kiawi, D.M.; Bakker, J.M.; Oomens, J.; Buma, W.J.; Jamshidi, Z.; Visscher, L.; Waters, L.B.F.M.

    2015-01-01

    Cationic cobalt clusters complexed with water Con+-​H2O (n = 6-​20) are produced through laser ablation and investigated via IR multiple photon dissocn. (IR-​MPD) spectroscopy in the 200-​1700 cm-​1 spectral range. All spectra exhibit a resonance close to the 1595 cm-​1 frequency of the free water

  13. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Leah J.; Holmes, Amie L. [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Kandpal, Sanjeev Kumar; Mason, Michael D. [Department of Chemical and Biological Engineering, University of Maine, Orono, ME (United States); Zheng, Tongzhang [Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT (United States); Wise, John Pierce, E-mail: John.Wise@usm.maine.edu [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States)

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity. - Highlights: • Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells. • Soluble cobalt induces more cytotoxicity compared to particulate cobalt. • Soluble and particulate cobalt induce similar levels of genotoxicity. • Particle-cell contact is required for particulate cobalt-induced toxicity.

  14. Electrocatalytic performance evaluation of cobalt hydroxide and cobalt oxide thin films for oxygen evolution reaction

    Science.gov (United States)

    Babar, P. T.; Lokhande, A. C.; Pawar, B. S.; Gang, M. G.; Jo, Eunjin; Go, Changsik; Suryawanshi, M. P.; Pawar, S. M.; Kim, Jin Hyeok

    2018-01-01

    The development of an inexpensive, stable, and highly active electrocatalyst for oxygen evolution reaction (OER) is essential for the practical application of water splitting. Herein, we have synthesized an electrodeposited cobalt hydroxide on nickel foam and subsequently annealed in an air atmosphere at 400 °C for 2 h. In-depth characterization of all the films using X-ray diffraction (XRD), X-ray photoelectron emission spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) techniques, which reveals major changes for their structural, morphological, compositional and electrochemical properties, respectively. The cobalt hydroxide nanosheet film shows high catalytic activity with 290 mV overpotential at 10 mA cm-2 and 91 mV dec-1 Tafel slope and robust stability (24 h) for OER in 1 M KOH electrolyte compared to cobalt oxide (340 mV). The better OER activity of cobalt hydroxide in comparison to cobalt oxide originated from high active sites, enhanced surface, and charge transport capability.

  15. Cobalt Fischer-Tropsch catalysts: influence of cobalt dispersion and titanium oxides promotion

    Energy Technology Data Exchange (ETDEWEB)

    Azib, H.

    1996-04-10

    The aim of this work is to study the effect of Sol-Gel preparation parameters which occur in silica supported cobalt catalysts synthesis. These catalysts are particularly used for the waxes production in natural gas processing. The solids have been characterized by several techniques: transmission electron microscopy (TEM), X-ray absorption near edge spectroscopy (XANES), programmed temperature reduction (TPR), infrared spectroscopy (IR), ultraviolet spectroscopy (UV), Magnetism, thermodesorption of H{sub 2} (TPD). The results indicate that the control of the cobalt dispersion and oxide phases nature is possible by modifying Sol-Gel parameters. The catalytic tests in Fischer-Tropsch synthesis were conducted on a pilot unit under pressure (20 atm) and suggested that turnover rates were independent of Co crystallite size, Co phases in the solids (Co deg., cobalt silicate) and titanium oxide promotion. On the other methane, the C{sub 3}{sup +} hydrocarbon selectivity is increased with increasing crystallite size. Inversely, the methane production is favoured by very small crystallites, cobalt silicate increase and titanium addition. However, the latter, used as a cobalt promoter, has a benefic effect on the active phase stability during the synthesis. (author). 149 refs., 102 figs., 71 tabs.

  16. Radiation and thermal effects on cobalt retention by Mexican aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Davila-Rangel, J.I. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico 11801, D. F. (Mexico); Unidad Academica Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Frac. La Penuela, Zacatecas, Zacatecas 98068 (Mexico); Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario No. 100 Col. Centro C. P. 50000, Toluca, Edo. de Mexico (Mexico); Solache-Rios, M. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico 11801, D. F. (Mexico)]. E-mail: msr@nuclear.inin.mx; Nunez-Monreal, J.E. [Unidad Academica de Ciencias Quimicas, Programa de Ingenieria Quimica, Universidad Autonoma de Zacatecas, Km. 0.5 Carr. a Cd. Cuauhtemoc., Guadalupe, Zacatecas 98600 (Mexico)

    2007-05-15

    Thermal and radiation effects on the leaching of cobalt from two cobalt exchanged zeolites and one clay were determined. The cobalt exchanged aluminosilicates were heated at different temperatures (500, 700, 900 and 1100 deg. C), and the materials were then treated with NaCl (1 and 5 M) and HNO{sub 3} (0.001 and 1 M) solutions to determine the leaching behavior of cobalt from the materials. Cobalt showed greater stability when the materials were heated at the highest temperature. The unheated samples and those heated at 1100 deg. C were gamma irradiated, and it was found that cobalt leaching from gamma irradiated aluminosilicates was higher than that for non-irradiated materials.

  17. A spot test for detection of cobalt release – early experience and findings

    DEFF Research Database (Denmark)

    Thyssen, Jacob P.; Menné, Torkil; Johansen, Jeanne D.

    2010-01-01

    Background: It is often difficult to establish clinical relevance of metal exposure in cobalt-allergic patients. Dermatologists and patients may incorrectly assume that many metallic items release cobalt at levels that may cause cobalt dermatitis. Cobalt-allergic patients may be unaware...... also be used as a gel test if combined with an agar preparation. We found no false-positive reactions when testing metals and alloys known not to contain cobalt. However, one cobalt-containing alloy, which elicited cobalt dermatitis in cobalt-allergic patients, was negative upon cobalt gel testing....... Conclusions: The cobalt test detects amounts of cobalt release that approximate the elicitation concentration seen in cobalt-allergic patients. It may serve as a useful tool in dermatology offices and workplaces....

  18. DC breakdown experiments with cobalt electrodes

    CERN Document Server

    Descoeudres, Antoine; Nordlund, Kai

    2009-01-01

    RF accelerating structures of the Compact Linear Collider (CLIC) require a material capable of sustaining high electric field with a low breakdown rate and low induced damage. Because of the similarity of many aspects of DC and RF breakdown, a DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultra-high vacuum in a simple setup. The conditioning speed, breakdown field and field enhancement factor of cobalt have been measured. The average breakdown field after conditioning reaches 615 MV/m, which places cobalt amongst the best materials tested so far. By comparison with results and properties of other metals, the high breakdown field of Co could be due to its high work function and maybe also to its hexagonal crystal structure. Geneva, Switzerland (June 2009) CLIC – Note – 875

  19. Process for obtaining cobalt and lanthanum nickelate

    International Nuclear Information System (INIS)

    Tapcov, V.; Samusi, N.; Gulea, A.; Horosun, I.; Stasiuc, V.; Petrenco, P.

    1999-01-01

    The invention relates to the process for obtaining polycrystalline ceramics of cobalt and lanthanum nickelate with the perovskite structure from coordinative hetero metallic compounds. The obtained products can be utilized in the industry in the capacity of catalysts. Summary of the invention consists in obtaining polycrystalline ceramics LaCoO 3 and LaNiO 3 with the perovskite structure by pyrolysis of the parent compounds, namely, the coordinative hetero metallic compounds of the lanthanum cobalt or lanthanum nickel. The pyrolysis of the parent compound runs during one hour at 800 C. The technical result of the invention consists in lowering the temperature of the parent compound pyrolysis containing the precise ratio of metals necessary for ceramics obtaining

  20. Cobalt oxides from crystal chemistry to physics

    CERN Document Server

    Raveau, Bernard

    2012-01-01

    Unparalleled in the breadth and depth of its coverage of all important aspects, this book systematically treats the electronic and magnetic properties of stoichiometric and non-stoichiometric cobaltites in both ordered and disordered phases. Authored by a pioneer and a rising star in the field, the monograph summarizes, organizes and streamlines the otherwise difficult-to-obtain information on this topic. An introductory chapter sets forth the crystal chemistry of cobalt oxides to lay the groundwork for an understanding of the complex phenomena observed in this materials class. Special emphasis is placed on a comprehensive discussion of cobaltite physical properties in different structural families. Providing a thorough introduction to cobalt oxides from a chemical and physical viewpoint as a basis for understanding their intricacies, this is a must-have for both experienced researchers as well as entrants to the field.

  1. Creep-fatigue of low cobalt superalloys

    Science.gov (United States)

    Halford, G. R.

    1982-01-01

    Testing for the low cycle fatigue and creep fatigue resistance of superalloys containing reduced amounts of cobalt is described. The test matrix employed involves a single high temperature appropriate for each alloy. A single total strain range, again appropriate to each alloy, is used in conducting strain controlled, low cycle, creep fatigue tests. The total strain range is based upon the level of straining that results in about 10,000 cycles to failure in a high frequency (0.5 Hz) continuous strain-cycling fatigue test. No creep is expected to occur in such a test. To bracket the influence of creep on the cyclic strain resistance, strain hold time tests with ore minute hold periods are introduced. One test per composition is conducted with the hold period in tension only, one in compression only, and one in both tension and compression. The test temperatures, alloys, and their cobalt compositions that are under study are given.

  2. Tensile strength of laser welded cobalt-chromium alloy with and without an argon atmosphere.

    Science.gov (United States)

    Tartari, Anna; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2010-06-01

    The tensile strength and depth of weld of two cobalt chromium alloys before and after laser welding with and without an argon gas atmosphere were investigated. Using two cobalt chromium alloys, rod shaped specimens (5 cm x 1.5 mm) were cast. Specimens were sand blasted, sectioned and welded with a pulsed Nd: YAG laser welding machine and tested in tension using an Instron universal testing machine. A statistically significant difference in tensile strength was observed between the two alloys. The tensile strength of specimens following laser welding was significantly less than the unwelded controls. Scanning electron microscopy showed that the micro-structure of the cast alloy was altered in the region of the weld. No statistically significant difference was found between specimens welded with or without an argon atmosphere.

  3. Cobalt metabolism and toxicology-A brief update

    Energy Technology Data Exchange (ETDEWEB)

    Simonsen, Lars Ole, E-mail: LOSimonsen@dadlnet.dk; Harbak, Henrik; Bennekou, Poul

    2012-08-15

    Cobalt metabolism and toxicology are summarized. The biological functions of cobalt are updated in the light of recent understanding of cobalt interference with the sensing in almost all animal cells of oxygen deficiency (hypoxia). Cobalt (Co{sup 2+}) stabilizes the transcriptional activator hypoxia-inducible factor (HIF) and thus mimics hypoxia and stimulates erythropoietin (Epo) production, but probably also by the same mechanism induces a coordinated up-regulation of a number of adaptive responses to hypoxia, many with potential carcinogenic effects. This means on the other hand that cobalt (Co{sup 2+}) also may have beneficial effects under conditions of tissue hypoxia, and possibly can represent an alternative to hypoxic preconditioning. Cobalt is acutely toxic in larger doses, and in mammalian in vitro test systems cobalt ions and cobalt metal are cytotoxic and induce apoptosis and at higher concentrations necrosis with inflammatory response. Cobalt metal and salts are also genotoxic, mainly caused by oxidative DNA damage by reactive oxygen species, perhaps combined with inhibition of DNA repair. Of note, the evidence for carcinogenicity of cobalt metal and cobalt sulfate is considered sufficient in experimental animals, but is as yet considered inadequate in humans. Interestingly, some of the toxic effects of cobalt (Co{sup 2+}) have recently been proposed to be due to putative inhibition of Ca{sup 2+} entry and Ca{sup 2+}-signaling and competition with Ca{sup 2+} for intracellular Ca{sup 2+}-binding proteins. The tissue partitioning of cobalt (Co{sup 2+}) and its time-dependence after administration of a single dose have been studied in man, but mainly in laboratory animals. Cobalt is accumulated primarily in liver, kidney, pancreas, and heart, with the relative content in skeleton and skeletal muscle increasing with time after cobalt administration. In man the renal excretion is initially rapid but decreasing over the first days, followed by a second, slow

  4. Leather Contains Cobalt and Poses a Risk of Allergic Contact Dermatitis: Cobalt Indicator Solution and X-ray Florescence Spectrometry as Screening Tests.

    Science.gov (United States)

    Hamann, Dathan; Hamann, Carsten R; Kishi, Patrick; Menné, Torkil; Johansen, Jeanne D; Thyssen, Jacob P

    2016-01-01

    Cobalt was recently identified in a leather couch responsible for dermatitis. Cobalt content/release in leather in the United States is unknown. We evaluated leather for cobalt content/release and investigated screening methods for identifying cobalt in leather. One hundred thirty-one leather swatches were screened for cobalt content/release with X-ray fluorescence (XRF) spectrometry and cobalt indicator solution (CIS). Samples with positive screens and 1 negative control were analyzed using inductively-coupled plasma mass spectrometry (ICPMS). CIS showed that 5 of 131 samples contained cobalt, subsequently found to be between 1 and 190 parts per million (ppm) when evaluated with ICPMS. The XRF analysis showed that 6 samples contained >5% cobalt, subsequently found to contain greater than 300 ppm cobalt by ICPMS. 7 of 12 tested swatches contained cobalt in excess of 100 ppm. One sample contained greater than 1000 ppm cobalt. The prevalence of swatches containing cobalt at levels in excess of 190 ppm was at least 5% (n = 7; total, N = 131). Some leather consumer goods contain and release cobalt. Cobalt indicator solution is a poor screening test for cobalt in leather while XRF screening may be effective. Leather is a new source of cobalt exposure. Exposures to metal allergens are changing in ways that impact clinical decision making.

  5. Infrared and Raman Spectroscopic Study of Carbon-Cobalt Composites

    Directory of Open Access Journals (Sweden)

    André Tembre

    2011-01-01

    Full Text Available Analysis of carbon-cobalt thin films using infrared spectroscopy has shown existence of carbon-cobalt stretching mode and great porosity. The Raman spectroscopy and high-resolution transmission electron microscopy have been used in order to investigate the microstructure of the films. These films exhibit complex Raman spectra suggesting the presence of amorphous and crystallized phases. The different fractions of phases and the correlation between the atomic bond structures and the Raman features depend on the cobalt content.

  6. Speciation studies of cobalt in sea water

    International Nuclear Information System (INIS)

    Toteja, R.S.D.; Sudersanan, M.; Iyer, R.K.

    1995-01-01

    Recent results on the speciation of cobalt in simulated and actual sea water is reported using ion exchangers. The influence of magnesium ions in affecting the composition of ion exchangers and subsequent interpretation of the results is discussed. The results indicated that Co +2 may predominate in both the simulated and actual sea water and the presence of other constituents in sea water does not affect the nature of complex species present. (author). 2 refs., 3 tabs., 1 fig

  7. Sputtering yield measurements on single crystal cobalt

    International Nuclear Information System (INIS)

    Chernysh, V.S.; Johansen, A.; Sarholt-Kristensen, L.

    1981-01-01

    Single crystals of cobalt have been bombarded with 80 keV A + ions in the direction of the h.c.p. structure and in the direction of the f.c.c. structure. The sputtering yields, measured by the weight loss method, depend on the crystal structure, and damage, introduced by the ion bombardment, is shown to play a significant role in the explanation of the measured sputtering yields. (Auth.)

  8. Photoionization of cobalt impuritiesin zinc oxide

    Czech Academy of Sciences Publication Activity Database

    Ivanov, V.; Godlewski, M.; Dejneka, Alexandr

    2015-01-01

    Roč. 252, č. 9 (2015), s. 1988-1992 ISSN 0370-1972 R&D Projects: GA MŠk(CZ) LM2011029; GA ČR GAP108/12/1941 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : absorption band * cobalt * photoionization * electron spin resonance * pulsed mode * ZnO Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.522, year: 2015

  9. High-Spin Cobalt Hydrides for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Patrick L. [Univ. of Rochester, NY (United States)

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  10. The cobalt radioactive isotopes in environment

    International Nuclear Information System (INIS)

    2007-01-01

    For the year 1993 the total activity released in cobalt is 69 GBq for the whole of nuclear power plants. The part of activity in cobalt for La Hague in 1993 is 8 GBq of 58 Co and 2 GBq of 60 Co. The radioactive isotopes released by nuclear power plants or the reprocessing plant of La Hague under liquid effluents are shared by half between 58 Co and 60 Co. The exposure to sealed sources is the most important risk for the cobalt. The risk of acute exposure can associate a local irradiation of several decades of grays inducing a radiological burns, deep burn to treat in surgery by resection or graft even amputation. A global irradiation of organism for several grays induces an acute irradiation syndrome, often serious. At long term the stochastic effects are represented by leukemia and radio-induced cancers. The increase of probability of their occurrence is 1% by sievert. We must remind that the natural spontaneous probability is 25%. (N.C.)

  11. Uptake of radionuclides caesium and cobalt

    International Nuclear Information System (INIS)

    Lukac, P.; Foldesova, M.

    1995-01-01

    By means of chemical treatment ammonium, potassium, sodium and H-form of zeolite were prepared. The chemical modifications of zeolite were carried out with: 2M solution of NaNO 3 , NH 4 NO 3 , KNO 3 ; 0,1M solution of HCl; NaOH solution of different concentration. The method of model radioactive solution was used to find the sorption ability for cesium and cobalt every modified zeolite. The model solution were 0.05M solution of cobalt labelled by 60 Co or cesium labelled by 137 Cs. The highest sorption ability was observed for zeolite modified by NaOH. The influence of pH on uptake of cesium and cobalt by modified zeolite was searched as well. The experimental data (leaching tests, compressive strength measurement and porosity) were measured for the case the Cs and Cs from model water solution and radioactive waste water were up taken on chemically modified zeolite and were subsequently incorporated into cement casts on blast furnace cement slags basis. The leachability was tested in water, in basis solution and in acid solution. The leachability in water and basic solution was negligible, in acid solution it was less than 4% which is inside of value of applied measure method. The compressive strength, porosity and leaching experiment are hopefully and show good mechanical stability and good retention of observed radionuclides in samples exposed in leaching solutions. (J.K.)

  12. Osseointegration of cobalt-chrome alloy implants.

    Science.gov (United States)

    Mavrogenis, Andreas F; Papagelopoulos, Panayiotis J; Babis, George C

    2011-01-01

    Osseointegration or osteointegration refers to a direct bone-to-metal interface without interposition of non-bone tissue. The long-term clinical success of bone implants is critically related to wide bone-to-implant direct contact. However, only poor bone formation or even host bone resorption have been shown where bone is in tight contact with the implant surface. It has been suggested that an appropriate space between implant and host bone may be useful for early peri-implant bone formation. Additionally, osseointegration depends on the topographical and chemical characteristics of the implant surface. Cobalt-chrome (Co-Cr) is a metal alloy of cobalt and chromium. Because of its high strength, temperature endurance and wear resistance, it is commonly used in dental and orthopedic implants. In orthopedic implants it is usually composed of cobalt with chromium, molybdenum, and traces of other elements. Co-Cr alloys are especially useful where high stiffness or a highly polished and extremely wear-resistant material is required. This article reviews the Co-Cr alloy orthopedic implants in terms of their properties, porous coating, osseointegration, outcome, and failure.

  13. Hot corrosion of low cobalt alloys

    Science.gov (United States)

    Stearns, C. A.

    1982-01-01

    The hot corrosion attack susceptibility of various alloys as a function of strategic materials content are investigated. Preliminary results were obtained for two commercial alloys, UDIMET 700 and Mar-M 247, that were modified by varying the cobalt content. For both alloys the cobalt content was reduced in steps to zero. Nickel content was increased accordingly to make up for the reduced cobalt but all other constituents were held constant. Wedge bar test samples were produced by casting. The hot corrosion test consisted of cyclically exposing samples to the high velocity flow of combustion products from an air-fuel burner fueled with jet A-1 and seeded with a sodium chloride aqueous solution. The flow velocity was Mach 0.5 and the sodium level was maintained at 0.5 ppm in terms of fuel plus air. The test cycle consisted of holding the test samples at 900 C for 1 hour followed by 3 minutes in which the sample could cool to room temperature in an ambient temperature air stream.

  14. Towards a Cycle without Loss. Cobalt in the Aircraft Industry,

    Science.gov (United States)

    COBALT , *AIRCRAFT INDUSTRY, *STRATEGIC MATERIALS, *MANUFACTURING, CYCLES, SUPERALLOYS , HIGH STRENGTH ALLOYS, STEEL, TOOL STEEL, ALLOYS, QUANTITATIVE ANALYSIS, MATERIALS RECOVERY, RATES, ALLOYS, RECYCLED MATERIALS, LOSSES, SYMPOSIA

  15. Consumer leather exposure: an unrecognized cause of cobalt sensitization

    DEFF Research Database (Denmark)

    Thyssen, J.P.; Johansen, Jeanne D.; Jellesen, Morten Stendahl

    2013-01-01

    BACKGROUND: A patient who had suffered from persistent generalized dermatitis for 7 years was diagnosed with cobalt sensitization, and his leather couch was suspected as the culprit, owing to the clinical presentation mimicking allergic chromium dermatitis resulting from leather furniture exposure...... have found high levels of cobalt sensitization, but not nickel sensitization, in patients with foot dermatitis. We raise the possibility that cobalt may be widely released from leather items, and advise dermatologists to consider this in patients with positive cobalt patch test reactions. © 2013 John...

  16. Measurement for cobalt target activity and its axial distribution

    International Nuclear Information System (INIS)

    Li Xingyuan; Chen Zigen.

    1985-01-01

    Cobalt target activity and its axial distribution are measured in process of producing radioactive isotopes 60 Co by irradiation in HFETR. Cobalt target activity is obtained with measured data at 3.60 m and 4.60 m, relative axial distribution of cobalt target activity is obtained with one at 30 cm, and axial distribution of cobalt target activity(or specific activity) is obtained with both of data. The difference between this specific activity and measured result for 60 Co teletherapy sources in the end is less than +- 5%

  17. Cobalt metabolism and toxicology—A brief update

    International Nuclear Information System (INIS)

    Simonsen, Lars Ole; Harbak, Henrik; Bennekou, Poul

    2012-01-01

    Cobalt metabolism and toxicology are summarized. The biological functions of cobalt are updated in the light of recent understanding of cobalt interference with the sensing in almost all animal cells of oxygen deficiency (hypoxia). Cobalt (Co 2+ ) stabilizes the transcriptional activator hypoxia-inducible factor (HIF) and thus mimics hypoxia and stimulates erythropoietin (Epo) production, but probably also by the same mechanism induces a coordinated up-regulation of a number of adaptive responses to hypoxia, many with potential carcinogenic effects. This means on the other hand that cobalt (Co 2+ ) also may have beneficial effects under conditions of tissue hypoxia, and possibly can represent an alternative to hypoxic preconditioning. Cobalt is acutely toxic in larger doses, and in mammalian in vitro test systems cobalt ions and cobalt metal are cytotoxic and induce apoptosis and at higher concentrations necrosis with inflammatory response. Cobalt metal and salts are also genotoxic, mainly caused by oxidative DNA damage by reactive oxygen species, perhaps combined with inhibition of DNA repair. Of note, the evidence for carcinogenicity of cobalt metal and cobalt sulfate is considered sufficient in experimental animals, but is as yet considered inadequate in humans. Interestingly, some of the toxic effects of cobalt (Co 2+ ) have recently been proposed to be due to putative inhibition of Ca 2+ entry and Ca 2+ -signaling and competition with Ca 2+ for intracellular Ca 2+ -binding proteins. The tissue partitioning of cobalt (Co 2+ ) and its time-dependence after administration of a single dose have been studied in man, but mainly in laboratory animals. Cobalt is accumulated primarily in liver, kidney, pancreas, and heart, with the relative content in skeleton and skeletal muscle increasing with time after cobalt administration. In man the renal excretion is initially rapid but decreasing over the first days, followed by a second, slow phase lasting several weeks, and

  18. Cobalt, nickel and chromium release from dental tools and alloys.

    Science.gov (United States)

    Kettelarij, Jolinde A B; Lidén, Carola; Axén, Emmy; Julander, Anneli

    2014-01-01

    Cobalt-chromium alloys are used as casting alloys by dental technicians when producing dental prostheses and implants. Skin exposure and metal release from alloys and tools used by the dental technicians have not been studied previously. To study the release of cobalt, nickel and chromium from alloys and tools that come into contact with the skin of dental technicians. Cobalt and nickel release from tools and alloys was tested with the cobalt spot test and the dimethylglyoxime test for nickel. Also, the release of cobalt, nickel and chromium in artificial sweat (EN1811) at different time-points was assessed. Analysis was performed with inductively coupled plasma-mass spectrometry. Sixty-one tools were spot tested; 20% released nickel and 23% released cobalt. Twenty-one tools and five dental alloys were immersed in artificial sweat. All tools released cobalt, nickel and chromium. The ranges were 0.0047-820, 0.0051-10 and 0.010-160 µg/cm(2) /week for cobalt, nickel and chromium, respectively. All dental alloys released cobalt in artificial sweat, with a range of 0.0010-17 µg/cm(2) /week, and they also released nickel and chromium at low concentrations. Sensitizing metals are released from tools and alloys used by dental technicians. This may cause contact allergy and hand eczema. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Cobalt Ions Improve the Strength of Epoxy Resins

    Science.gov (United States)

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

    1986-01-01

    Technique developed for improving mechanical strength of epoxy resins by adding cobalt ions in form of tris(acetylacetonato)cobalt (III) complex. Solid cast disks prepared from cobalt ion-containing epoxy resins tested for flexural strength and stiffness. Incorporation of cobalt ions into epoxies increased flexural strength of resins by 10 to 95 percent. Suitable resins for this technique include any liquid or solid TGMDA resins. Improved epoxy formulation proves useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft.

  20. Pharmacokinetics of inorganic cobalt and a vitamin B12 supplement in the Thoroughbred horse: Differentiating cobalt abuse from supplementation.

    Science.gov (United States)

    Hillyer, L L; Ridd, Z; Fenwick, S; Hincks, P; Paine, S W

    2018-05-01

    While cobalt is an essential micronutrient for vitamin B 12 synthesis in the horse, at supraphysiological concentrations, it has been shown to enhance performance in human subjects and rats, and there is evidence that its administration in high doses to horses poses a welfare threat. Animal sport regulators currently control cobalt abuse via international race day thresholds, but this work was initiated to explore means of potentially adding to application of those thresholds since cobalt may be present in physiological concentrations. To devise a scientific basis for differentiation between presence of cobalt from bona fide supplementation and cobalt doping through the use of ratios. Six Thoroughbred horses were given 10 mL vitamin B 12 /cobalt supplement (Hemo-15 ® ; Vetoquinol, Buckingham, Buckinghamshire, UK., 1.5 mg B 12 , 7 mg cobalt gluconate = 983 μg total Co) as an i.v. bolus then an i.v. infusion (15 min) of 100 mg cobalt chloride (45.39 mg Co) 6 weeks later. Pre-and post-administration plasma and urine samples were analysed for cobalt and vitamin B 12 . Urine and plasma samples were analysed for vitamin B 12 using an immunoassay and cobalt concentrations were measured via ICP-MS. Baseline concentrations of cobalt in urine and plasma for each horse were subtracted from their cobalt concentrations post-administration for the PK analysis. Compartmental analysis was used for the determination of plasma PK parameters for cobalt using commercially available software. On administration of a vitamin B 12 /cobalt supplement, the ratio of cobalt to vitamin B 12 in plasma rapidly increased to approximately 3 and then rapidly declined below a ratio of 1 and then back to near baseline over the next week. On administration of 100 mg cobalt chloride, the ratio initially exceeded 10 in plasma and then declined with the lower 95% confidence interval remaining above a ratio of 1 for 7 days. For two horses with extended sampling, the plasma ratio remained above one for

  1. Study of complex formation of cobalt (II) and cobalt (III) in acrylamide aqueous solutions and in the phase of acrylamide hydrogel

    International Nuclear Information System (INIS)

    Ismailova, M.M.; Egorova, L.A.; Khamidov, B.O.

    1993-01-01

    Present article is devoted to study of complex formation of cobalt (II) and cobalt (III) in acrylamide aqueous solutions and in the phase of acrylamide hydrogel. The condition of cobalt in various rate of oxidation in acrylamide aqueous solutions was studied. The concentration conditions of stability of system Co(II)-Co(III) were defined. The composition of coordination compounds of cobalt (II) and cobalt (III) in acrylamide aqueous solutions and in the phase of acrylamide hydrogel was determined.

  2. Dosing of anaerobic granular sludge bioreactors with cobalt: Impact of cobalt retention on methanogenic activity

    KAUST Repository

    Fermoso, Fernando G.

    2010-12-01

    The effect of dosing a metal limited anaerobic sludge blanket (UASB) reactor with a metal pulse on the methanogenic activity of granular sludge has thus far not been successfully modeled. The prediction of this effect is crucial in order to optimize the strategy for metal dosage and to prevent unnecessary losses of resources. This paper describes the relation between the initial immobilization of cobalt in anaerobic granular sludge cobalt dosage into the reactor and the evolution of methanogenic activity during the subsequent weeks. An operationally defined parameter (A0· B0) was found to combine the amount of cobalt immobilized instantaneously upon the pulse (B0) and the amount of cobalt immobilized within the subsequent 24. h (A0). In contrast with the individual parameters A0 and B0, the parameter A0· B0 correlated significantly with the methanogenic activity of the sludge during the subsequent 16 or 35. days. This correlation between metal retention and activity evolution is a useful tool to implement trace metal dosing strategies for biofilm-based biotechnological processes. © 2010.

  3. Cobalt(I) and Cobalt(III) Cyclopentadienyl Complexes with New Silicon-branched Fluorous Tags

    Czech Academy of Sciences Publication Activity Database

    Strašák, Tomáš; Čermák, Jan; Červenková Šťastná, Lucie; Sýkora, Jan; Fajgar, Radek

    2014-01-01

    Roč. 159, MAR 2014 (2014), s. 15-20 ISSN 0022-1139 R&D Projects: GA ČR(CZ) GAP106/12/1372 Institutional support: RVO:67985858 Keywords : fluorous tag * cobalt complex * cyclopentadienyl complex Subject RIV: CC - Organic Chemistry Impact factor: 1.948, year: 2014

  4. Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation

    NARCIS (Netherlands)

    Patntirapong, Somying; Habibovic, Pamela; Hauschka, Peter V.

    2009-01-01

    Metal ions originating from mechanical debris and corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+), which is a major component of cobalt–chromium-based implant alloys and a known

  5. Bioactivity and mechanical behaviour of cobalt oxide-doped ...

    Indian Academy of Sciences (India)

    evaluation through scanning electron microscopy. Densities and mechanical properties of the samples were found to increase considerably with an increase in the concentration of cobalt oxide. Keywords. Bioactive glass; cobalt oxide; FTIR spectrometry; SEM and mechanical properties. 1. Introduction. Some materials like ...

  6. Comparative toxicity and carcinogenicity of soluble and insoluble cobalt compounds.

    Science.gov (United States)

    Behl, Mamta; Stout, Matthew D; Herbert, Ronald A; Dill, Jeffrey A; Baker, Gregory L; Hayden, Barry K; Roycroft, Joseph H; Bucher, John R; Hooth, Michelle J

    2015-07-03

    Occupational exposure to cobalt is of widespread concern due to its use in a variety of industrial processes and the occurrence of occupational disease. Due to the lack of toxicity and carcinogenicity data following exposure to cobalt, and questions regarding bioavailability following exposure to different forms of cobalt, the NTP conducted two chronic inhalation exposure studies in rats and mice, one on soluble cobalt sulfate heptahydrate, and a more recent study on insoluble cobalt metal. Herein, we compare and contrast the toxicity profiles following whole-body inhalation exposures to these two forms of cobalt. In general, both forms were genotoxic in the Salmonella T98 strain in the absence of effects on micronuclei. The major sites of toxicity and carcinogenicity in both chronic inhalation studies were the respiratory tract in rats and mice, and the adrenal gland in rats. In addition, there were distinct sites of toxicity and carcinogenicity noted following exposure to cobalt metal. In rats, carcinogenicity was observed in the blood, and pancreas, and toxicity was observed in the testes of rats and mice. Taken together, these findings suggest that both forms of cobalt, soluble and insoluble, appear to be multi-site rodent carcinogens following inhalation exposure. Published by Elsevier Ireland Ltd.

  7. Synthesis and phosphatase activity of a Cobalt(II) phenanthroline ...

    Indian Academy of Sciences (India)

    MAMONI GARAI

    2017-09-19

    Sep 19, 2017 ... The cobalt(II) complex has been evaluated as a functional model for phosphatase enzyme by using 4-nitrophenylphosphate. (PNPP) as a standard substrate in aqueous DMF medium. ... Designed coordination molecules with an ability to mimic the ... tion, cobalt complexes have gained importance because.

  8. Sorghum cobalt analysis on not determined wave length with atomic ...

    African Journals Online (AJOL)

    Jane

    2011-08-24

    Aug 24, 2011 ... right wave length for cobalt analysis with the atomic absorption spectrophotometer method. And this problem on wave length might exist also on the inductively coupled plasma spectroscopy (ICP) method. The wave length generally employed for cobalt determination is. 240.7 nm (Shapiro and Martin, 1988) ...

  9. Electrical and Magnetic Properties of Polyvinyl Alcohol-Cobalt ...

    Indian Academy of Sciences (India)

    7

    [14] has reported the electrical transport properties of polyvinyl alcohol- selenium nanocomposite ... of Cobalt Ferrite Nanoparticles. Cobalt Ferrite nanoparticles are synthesized by wet chemical method using raw materials of ... constantly stirred using the magnetic stirrer until the pH level reached to 12. A specified amount.

  10. IN SITU AND POST REACTION COBALT-INCORPORATION INTO ...

    African Journals Online (AJOL)

    a

    such as the nitroaldol condensation and Michael addition reactions [38, 39]. Although unfunctionalized silica materials, including ordered mesoporous silicas (MCM 41) have been used as supports for cobalt-based catalysts in the Fischer Tropsch (FT) synthesis [40 –. 42], there are very few reports in the literature on cobalt ...

  11. Two new twisted helical nickel (II) and cobalt (III) octahedral ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 6. Two new twisted helical nickel(II) and cobalt(III) octahedral monomer complexes: Synthesis and structural characterization. Malay Dolai ... Keywords. Coordination chemistry; nickel(II); cobalt(III); Schiff base; twisted helicity; supramolecular interactions.

  12. Cobalt nanoparticles as reusable catalysts for reduction of 4 ...

    Indian Academy of Sciences (India)

    Abstract. Facile reduction of p-nitrophenol to p-aminophenol by sodium borohydride catalysed by cobalt nanopar- ticles (CoNPs) has been discussed. A simple approach has been made to synthesize highly active and ordered structures of CoNPs. The air-stable nanoparticles were prepared from cobalt sulphate using ...

  13. Study to use graded cobalt adjuster in 540 MWe PHWR

    International Nuclear Information System (INIS)

    Raj, Manish; Fernando, M.P.S.; Pradhan, A.S.; Kumar, A.N.

    2007-01-01

    Full text: There are 17 adjusters in 540 MWe PHWR, which are essentially provided for xenon override function. They also provide flux flattening being in the central region of the reactor core. The present design of adjusters consists of stainless steel tube. The adjuster rods are grouped into 8 banks for movement. Since adjusters are normally fully inserted during reactor operation, they are best suited for production of cobalt 60. The nickel-plated cobalt in the form of either slugs or pellet are used for the design of cobalt pencils. The number of pencils can be varied to optimize the reactivity load and cobalt 60 production requirement. The worth and activity of cobalt adjusters have been worked out considering different pin configuration for the adjuster assembly. To start with we have assumed all adjusters throughout its length are of the same configuration. The flux depression factors within the cobalt pencils have been considered in the estimations of the specific and total cobalt 60 activities. The option of using graded cobalt adjusters, where different pin configuration along the length is considered for better flux flattening

  14. Surface oxidation of cobalt nanoparticles studied by Mossbauer spectroscopy

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Charles, S.W.

    1999-01-01

    The surface oxide formed on cobalt nanoparticles has been studied by Mossbauer emission spectroscopy. Exposure of the cobalt particles to oxygen at room temperature was found to result in the formation of a relatively well-ordered surface oxide with Mossbauer parameters similar to those of CoO....

  15. Synthesis and Characterization of a Schiff Base Cobalt (III) Complex ...

    African Journals Online (AJOL)

    2017-12-18

    Dec 18, 2017 ... activities at a concentration even higher than the compound which confirmed that chelation of ligand with cobalt ion was significant for the activity of this novel compound. The cobalt compound activated caspase-3 via the intrinsic mitochondrial apoptotic pathway resulting in induces apoptosis on MCF-7 cell ...

  16. Optimal thickness calculation of cobalt targets in HFETR

    International Nuclear Information System (INIS)

    Liu Shuiqing; Peng Feng

    1995-01-01

    The ANISN code, which is more exact than 'blacken-theory', is used to calculate the thickness of cobalt targets of 'sandwich' type structure in HFETR core. Result shows: there is a wide radioactivity peak when the cobalt thickness is between 2.5 mm and 3.0 mm, the optimal thickness of maximum's radioactivity is about 2.9 mm

  17. Removal of copper and cobalt from aqueous solutions using natural ...

    African Journals Online (AJOL)

    Synthetic non-mixed sulphate solutions of copper and cobalt recorded maximum cation uptakes of 79% and 63% with 0.02 M HCl-activated clinoptilolite respectively. From the Cu/Co mixed solutions, both cobalt and copper recorded a 79% uptake with 0.02 M HCl-activation. The 0.04 M HCl activation gave percentage ...

  18. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cobaltous salts and its derivatives. 189.120 Section 189.120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... malt beverages as a foam stabilizer and to prevent “gushing.” (b) Food containing any added cobaltous...

  19. The role of cobalt on the creep of Waspaloy

    Science.gov (United States)

    Jarrett, R. N.; Chin, L.; Tien, J. K.

    1984-01-01

    Cobalt was systematically replaced with nickel in Waspaloy (which normally contains 13% Co) to determine the effects of cobalt on the creep behavior of this alloy. Effects of cobalt were found to be minimal on tensile strengths and microstructure. The creep resistance and the stress rupture resistance determined in the range from 704 to 760 C (1300 to 1400 C) were found to decrease as cobalt was removed from the standard alloy at all stresses and temperatures. Roughly a ten-fold drop in rupture life and a corresponding increase in minimum creep rate were found under all test conditions. Both the apparent creep activation energy and the matrix contribution to creep resistance were found to increase with cobalt. These creep effects are attributed to cobalt lowering the stacking fault energy of the alloy matrix. The creep resistance loss due to the removal of cobalt is shown to be restored by slightly increasing the gamma' volume fraction. Results are compared to a previous study on Udimet 700, a higher strength, higher gamma' volume fraction alloy with similar phase chemistry, in which cobalt did not affect creep resistance. An explanation for this difference in behavior based on interparticle spacing and cross-slip is presented.

  20. Microwave Mapping Demonstration Using the Thermochromic Cobalt Chloride Equilibrium

    Science.gov (United States)

    Nguyen, Vu D.; Birdwhistell, Kurt R.

    2014-01-01

    An update to the thermochromic cobalt(II) chloride equilibrium demonstration is described. Filter paper that has been saturated with aqueous cobalt(II) chloride is heated for seconds in a microwave oven, producing a color change. The resulting pink and blue map is used to colorfully demonstrate Le Châtelier's principle and to illuminate the…

  1. Effect of 1,2,4-triazole on galvanic corrosion between cobalt and copper in CMP based alkaline slurry

    Science.gov (United States)

    Fu, Lei; Liu, Yuling; Wang, Chenwei; Han, Linan

    2018-04-01

    Cobalt has become a new type of barrier material with its unique advantages since the copper-interconnects in the great-large scale integrated circuits (GLSI) into 10 nm and below technical nodes, but cobalt and copper have severe galvanic corrosion during chemical–mechanical flattening. The effect of 1,2,4-triazole on Co/Cu galvanic corrosion in alkaline slurry and the control of rate selectivity of copper and cobalt were investigated in this work. The results of electrochemical experiments and polishing experiments had indicated that a certain concentration of 1,2,4-triazole could form a layer of insoluble and dense passive film on the surface of cobalt and copper, which reduced the corrosion potential difference between cobalt and copper. Meantime, the removal rate of cobalt and copper could be effectively controlled according to demand during the CMP process. When the study optimized slurry was composed of 0.5 wt% colloidal silica, 0.1 %vol. hydrogen peroxide, 0.05 wt% FA/O, 345 ppm 1,2,4-triazole, cobalt had higher corrosion potential than copper and the galvanic corrosion could be reduced effectively when the corrosion potential difference between them decreased to 1 mV and the galvanic corrosion current density reached 0.02 nA/cm2. Meanwhile, the removal rate of Co was 62.396 nm/min, the removal rate of Cu was 47.328 nm/min, so that the removal rate ratio of cobalt and copper was 1.32 : 1, which was a good amendment to the dishing pits. The contact potential corrosion of Co/Cu was very weak, which could be better for meeting the requirements of the barrier CMP. Project supported by the Major National Science and Technology Special Projects (No. 2016ZX02301003-004-007), the Natural Science Foundation of Hebei Province, China (No. F2015202267), and the Outstanding Young Science and Technology Innovation Fund of Hebei University of Technology (No. 2015007).

  2. A Systematic Review of Systemic Cobaltism After Wear or Corrosion of Chrome-Cobalt Hip Implants.

    Science.gov (United States)

    Gessner, Bradford D; Steck, Thomas; Woelber, Erik; Tower, Stephen S

    2015-06-12

    We sought to synthesize data on systemic arthroprosthetic cobaltism, a recently described syndrome that results from wear or corrosion of chrome-cobalt hip components. We conducted a systematic literature review to identify all reported cases of systemic arthroprosthetic cobaltism. To assess the epidemiologic link between blood cobalt levels (B[Co]), we developed a symptom scoring tool that evaluated 9 different symptom categories and a category of medical utilization. We identified 25 patients reported between 2001 and 2014 with a substantial increase in case reports over the past 3 years. Symptoms were diverse and involved the hip (84%), cardiovascular system (60%), audiovestibular system (52%), peripheral motor-sensory system (48%), thyroid (48%), psychological functioning (32%), visual system (32%), and the hematological, oncological, or immune system (20%). The mean latency from implantation to presentation or revision was 41 months (range, 9-99 months). The mean B[Co] was 324 μg/L and 4 patients had levels less than 20 μg/L. The B[Co] but not blood chromium level was highly associated with a quantitative measure of overall symptom severity (r, 0.81; P chrome-cobalt hip implants, may involve a large number of organ systems, and may occur with relatively low B[Co]. There is an urgent need to better define the overall scope of the problem and to develop screening and management strategies.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.

  3. Magnetic circular dichroic spectra of cobalt(II) substituted metalloenzymes.

    Science.gov (United States)

    Holmquist, B; Kaden, T A; Vallee, B L

    1975-04-08

    The magnetic circular dichroic (MCD) spectra of cobalt(II) sugstituted metalloenzymes have been studied and compared to a series of four-, five-, and six-coordinate cobalt(II) model complexes previously examined (T. A. Kaden et al. (1974), Inorg. Chem. 13, 2582). The MCD spectra of cobalt substituted carboxypeptidase A, procarboxypeptidase ta, and thermolysin are consistent with earlier deductions of tetrahedral coordination from absorption spectra and also with X-ray structure analysis. Inhibitors fail to alter their MCD spectra significantly. The MCD spectra of cobalt alkaline phosphatase and carbonic anhydrase are more complex and their pH dependence and alteration by inhibitors are discussed in terms of known cobalt(II) models.

  4. Total body irradiation with a reconditioned cobalt teletherapy unit.

    Science.gov (United States)

    Evans, Michael D C; Larouche, Renée-Xavière; Olivares, Marina; Léger, Pierre; Larkin, Joe; Freeman, Carolyn R; Podgorsak, Ervin B

    2006-01-01

    While the current trend in radiotherapy is to replace cobalt teletherapy units with more versatile and technologically advanced linear accelerators, there remain some useful applications for older cobalt units. The expansion of our radiotherapy department involved the decommissioning of an isocentric cobalt teletherapy unit and the replacement of a column-mounted 4-MV LINAC that has been used for total body irradiation (TBI). To continue offering TBI treatments, we converted the decommissioned cobalt unit into a dedicated fixed-field total body irradiator and installed it in an existing medium-energy LINAC bunker. This article describes the logistical and dosimetric aspects of bringing a reconditioned cobalt teletherapy unit into clinical service as a total body irradiator.

  5. Cobalt60 plaques in recurrent retinoblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Fass, D.; McCormick, B.; Abramson, D.; Ellsworth, R. (Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, NY, NY (USA))

    1991-08-01

    Cobalt60 plaque irradiation is one treatment option for patients with recurrent retinoblastoma following conventional external beam irradiation (ERT). Tumorocidal doses can be delivered without excessive risk of normal tissue injury. In patients not considered candidates for xenon arc or cryotherapy, 60Co is an alternative to enucleation. Between 1968 and 1987, 85 patients were treated with 60Co plaques, 72 of whom had failed prior ERT. Age at diagnosis ranged from 1 week to 4 years. There are 37 males and 35 females. Seventy-one patients had bilateral disease and one had unilateral. Three patients had both eyes plaqued. Prior ERT ranged from 30 to 70 Gy (mean 4200 Gy). Time from initial therapy to failure ranged from 13 to 60 months. Cobalt plaques of 10 mm, 15 mm, or 10 {times} 15 mm were used depending on tumor size and location. Dose prescribed to the apex of the tumor ranged from 30 to 50 Gy (median 40 Gy) given over 3 to 8 days. Twelve patients had two plaque applications; three patients had three plaque applications. All patients were followed with routine ophthalmoscopic examinations. Follow-up ranged from 2 to 22 years (mean 8.7). Seven patients died of metastatic disease; 10 patients developed non-ocular second tumors. Thirty patients required enucleation. Twenty-two patients had clear tumor progression, two patients had radiation complications, and six patients had a combination of tumor growth and complications. Cobalt60 can salvage eyes in retinoblastoma patients failing ERT. Currently, the authors are using I125 in an attempt to spare normal ocular tissue and reduce subsequent complications.

  6. Cobalt ferrite nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Saccone, F. D.; Ferrari, S.; Grinblat, F.; Bilovol, V. [Instituto de Tecnologías y Ciencias de la Ingeniería, “Ing. H. Fernández Long,” Av. Paseo Colón 850 (1063), Buenos Aires (Argentina); Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Fisica Aplicada, Institut Universitari de Ciència dels Materials, Universitat de Valencia, c/ Doctor Moliner 50, E-46100 Burjassot, Valencia (Spain); Agouram, S. [Departamento de Física Aplicada y Electromagnetismo, Universitat de València, 46100 Burjassot, Valencia (Spain)

    2015-08-21

    We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B{sub 0} = 204 GPa) is considerably larger than the value previously reported for bulk CoFe{sub 2}O{sub 4} (B{sub 0} = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B{sub 0} = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.

  7. Cobalt60 plaques in recurrent retinoblastoma

    International Nuclear Information System (INIS)

    Fass, D.; McCormick, B.; Abramson, D.; Ellsworth, R.

    1991-01-01

    Cobalt60 plaque irradiation is one treatment option for patients with recurrent retinoblastoma following conventional external beam irradiation (ERT). Tumorocidal doses can be delivered without excessive risk of normal tissue injury. In patients not considered candidates for xenon arc or cryotherapy, 60Co is an alternative to enucleation. Between 1968 and 1987, 85 patients were treated with 60Co plaques, 72 of whom had failed prior ERT. Age at diagnosis ranged from 1 week to 4 years. There are 37 males and 35 females. Seventy-one patients had bilateral disease and one had unilateral. Three patients had both eyes plaqued. Prior ERT ranged from 30 to 70 Gy (mean 4200 Gy). Time from initial therapy to failure ranged from 13 to 60 months. Cobalt plaques of 10 mm, 15 mm, or 10 x 15 mm were used depending on tumor size and location. Dose prescribed to the apex of the tumor ranged from 30 to 50 Gy (median 40 Gy) given over 3 to 8 days. Twelve patients had two plaque applications; three patients had three plaque applications. All patients were followed with routine ophthalmoscopic examinations. Follow-up ranged from 2 to 22 years (mean 8.7). Seven patients died of metastatic disease; 10 patients developed non-ocular second tumors. Thirty patients required enucleation. Twenty-two patients had clear tumor progression, two patients had radiation complications, and six patients had a combination of tumor growth and complications. Cobalt60 can salvage eyes in retinoblastoma patients failing ERT. Currently, the authors are using I125 in an attempt to spare normal ocular tissue and reduce subsequent complications

  8. Cobalt-Chromium Metallosis With Normal Electroretinogram.

    Science.gov (United States)

    Grillo, Lola M; Nguyen, Huy V; Tsang, Stephen H; Hood, Donald C; Odel, Jeffrey G

    2016-12-01

    Ocular cobalt toxicity is a rare phenomenon reported with increased frequency due to the rise of cobalt-chromium metal hip implants. We report the case of a 66-year-old previously healthy man who developed decreased vision due to cobalt-chromium toxicity from a metal-on-metal hip arthroplasty. Our objective was to determine whether the origin of his visual loss was due to toxicity of the optic nerve, of the retina, or of both. Ocular examination, 10-2 SITA-Standard Humphrey Visual Field (VF), standard full-field electroretinogram (ERG) as indicated by the International Society for Clinical Electrophysiology of Vision (ISCEV), multifocal electroretinogram (mfERG), multifocal visual evoked potentials (mfVEP), and optical coherence tomography (OCT) were conducted. Ocular examination revealed decreased visual acuity, poor color vision, normal funduscopy, and cecocentral scotomas on VF testing. Because his right eye was amblyopic since childhood, test results from only the left eye are shown. Electrophysiology studies revealed an ISCEV standard full-field ERG with photopic and scotopic responses within normal limits, mfERG with amplitudes and latencies within normal limits, and mfVEP with latencies within normal limits, but with decreased central amplitudes. Peripapillary and macular OCT showed retinal nerve fiber layer and retinal ganglion cell-inner plexiform layer thickness within normal limits. Because decreased color vision and cecocentral scotoma on 10-2 VF are most consistent with toxic optic neuropathy, and decreased central amplitudes on mfVEP are suggestive of neural dysfunction, we hypothesize that our patient presented with an early stage of optic nerve toxicity that was not yet apparent as a structural abnormality on OCT.

  9. Low-Cobalt Powder-Metallurgy Superalloy

    Science.gov (United States)

    Harf, F. H.

    1986-01-01

    Highly-stressed jet-engine parts made with less cobalt. Udimet 700* (or equivalent) is common nickel-based superalloy used in hot sections of jet engines for many years. This alloy, while normally used in wrought condition, also gas-atomized into prealloyed powder-metallurgy (PM) product. Product can be consolidated by hot isostatically pressing (HIPPM condition) and formed into parts such as turbine disk. Such jet-engine disks "see" both high stresses and temperatures to 1,400 degrees F (760 degrees C).

  10. Cyanidotetra-kis-(trimethyl-phosphine)cobalt(I).

    Science.gov (United States)

    Xu, Xiaofeng; Feng, Lei; Li, Xiaoyan

    2011-04-01

    The title compound, [Co(CN)(C(3)H(9)P)(4)], was obtained as a product of the reaction of [Co(PMe(3))(4)] with a molar equivalent of 2,6-difluoro-benzonitrile in diethyl ether. This compound is stable in the air for several hours, but rapidly decomposes at room temperature in solution. The cobalt(I) atom has s trigonal-bipyramidal coordination enviroment in which the cyano group and one of the PMe(3) groups are in the axial positions.

  11. HYDROCARBON FORMATION ON POLYMER-SUPPORTED COBALT

    Energy Technology Data Exchange (ETDEWEB)

    Benner, Linda S.; Perkins, Patrick; Vollhardt, K.Peter C.

    1980-10-01

    In this report we detail the synthesis catalytic chemistry of polystyrene supported {eta}{sup 5} ~cyclopentadienyl- dicarbonyl cobalt, CpCo(CO){sub 2}. This material is active in the hydrogenation of CO to saturated linear hydrocarbons and appears to retain its "homogeneous", mononuclear character during the course of its catalysis, During ·the course of our work 18% and 20% crosslinked analogs of polystyrene supported CpCo(CO){sub 2} were shown to exhibit limited catalytic activity and no CO activation.

  12. Future of U.S. cobalt irradiation

    International Nuclear Information System (INIS)

    Clouser, J.F.

    1995-01-01

    An examination of future cobalt needs requires us to review our base business, customer trends, technology trends, and people, the human aspect of our business. I am approaching this discussion from the perspective of a contract supplier of gamma irradiation services in the United States. The base business is comprised primarily of the sterilization of medical devices followed by containers, labware, food products, and other items. Since the core business is serving the medical industry, trends observed within medical device manufacturers can impact our growth and the type of services needed to support that industry. (author)

  13. Bifunctional cobalt F-T catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.G.; Coughlin, P.K.; Yang, C.L.; Rabo, J.A.

    1986-03-01

    Results on the catalytic screening of Fischer-Tropsch catalysts containing shape selective components are reported. Catalysts consist of promoted cobalt intimately contacted with Union Carbide molecular sieves and were tested using a Berty type internally recycled reactor. Methods of preparation, promoters and shape selective components were varied and aimed at improving catalyst performance. Catalysts were developed demonstrating high C/sub 5/ + yields with high olefin content and low methane production while maintaining stability under both low and high H/sub 2/:CO ratio conditions.

  14. Nitrogen oxides storage catalysts containing cobalt

    Science.gov (United States)

    Lauterbach, Jochen; Snively, Christopher M.; Vijay, Rohit; Hendershot, Reed; Feist, Ben

    2010-10-12

    Nitrogen oxides (NO.sub.x) storage catalysts comprising cobalt and barium with a lean NO.sub.x storage ratio of 1.3 or greater. The NO.sub.x storage catalysts can be used to reduce NO.sub.x emissions from diesel or gas combustion engines by contacting the catalysts with the exhaust gas from the engines. The NO.sub.x storage catalysts can be one of the active components of a catalytic converter, which is used to treat exhaust gas from such engines.

  15. Diffusion of cobalt in alpha zirconium

    International Nuclear Information System (INIS)

    Ghosh, U.; Pruthi, D.D.; Anand, M.S.

    1979-01-01

    The diffusion of 60 Co in alpha zirconium has been studied in the temperature range of 873-1123 K using the sectioning technique. The diffusion parameters obey the following Arrhenius equation:- D = (1.132 +- 0.22)10 -4 exp((-136.43 +- 3.50 KJ)/RT)m 2 s -1 . The diffusivity in this phase is as high as that observed in β-phase. It is also about five orders of magnitude higher when compared to the self diffusion values. The high diffusivity of cobalt in alpha zirconium has been explained on the basis of an interstitial mechanism. (auth.)

  16. Electronic structure of cobalt nanocrystals suspended inliquid

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongjian; Guo, Jinghua; Yin, Yadong; Augustsson, Andreas; Dong, Chungli; Nordgren, Joseph; Chang, Chinglin; Alivisatos, Paul; Thornton, Geoff; Ogletree, D. Frank; Requejo, Felix G.; de Groot, Frank; Salmeron, Miquel

    2007-07-16

    The electronic structure of cobalt nanocrystals suspended in liquid as a function of size has been investigated using in-situ x-ray absorption and emission spectroscopy. A sharp absorption peak associated with the ligand molecules is found that increases in intensity upon reducing the nanocrystal size. X-ray Raman features due to d-d and to charge-transfer excitations of ligand molecules are identified. The study reveals the local symmetry of the surface of {var_epsilon}-Co phase nanocrystals, which originates from a dynamic interaction between Co nanocrystals and surfactant + solvent molecules.

  17. Comparative study of the acute lung toxicity of pure cobalt powder and cobalt-tungsten carbide mixture in rat.

    Science.gov (United States)

    Lasfargues, G; Lison, D; Maldague, P; Lauwerys, R

    1992-01-01

    Alveolitis progressing to lung fibrosis has been reported in workers exposed to cobalt containing dust (e.g., tungsten carbide-cobalt mixture as produced by the hard metal industry) but rarely following exposure to pure cobalt dust (e.g., in cobalt-producing factories). We have previously demonstrated that tungsten carbide-cobalt mixture is more toxic toward rat alveolar macrophages in vitro than pure cobalt metal powder. The present study was undertaken to compare in female rats the acute pulmonary response (lung weight, lung histology, cellular and biochemical analyses of bronchoalveolar lavage fluid, and mortality) following the intratracheal instillation of pure cobalt (Co) particles (median particle size, d50:4 microns), pure tungsten carbide (WC) particles (d50:2 microns), tungsten carbide-cobalt (WC-Co) powder (d50:2 microns; cobalt 6.3%, tungsten 84%, carbon 5.4%) and crystalline silica (d50 less than 5 micron) used as pneumotoxic reference material. WC alone (15.67 mg/100 g body wt) behaves as an inert dust producing only a mild accumulation of macrophages in the alveolar duct walls. Co alone (1.0 mg/100 g) only causes a moderate inflammatory response. An identical amount of Co given as WC-Co mixture (16.67 mg/100 g; corresponding to 1.0 mg Co/100 g) produces a severe alveolitis and fatal pulmonary edema. Cellular and biochemical characteristics of bronchoalveolar lavage fluid collected 24 hr after the intratracheal instillation of WC (1.0 mg/100 g) or Co (0.06 mg/100 g) are not significantly different from those of control animals instilled with sterile saline. On the contrary, bronchoalveolar lavage fluid changes following administration of the WC-Co mixture (1.0 mg/100 g; corresponding to 0.06 mg Co/100 g) are very similar to those induced by crystalline silica (1.0 mg/100 g). The amount of cobalt excreted in urine is significantly higher when the animals are exposed to WC-Co powder as compared to an equivalent amount of pure cobalt particles

  18. Comparison of supplemental cobalt form on fibre digestion and cobalamin concentrations in cattle

    Science.gov (United States)

    Cobalt is essential for rumen microbial metabolism to synthesize methane, acetate and methionine. It also serves as a structural component of vitamin B12, which functions as a coenzyme in energy metabolism. A study was conducted to determine if cobalt form (cobalt carbonate vs cobalt glucoheptonate...

  19. The Cytotoxicity and Genotoxicity of Particulate and Soluble Cobalt in Human Urothelial Cells.

    Science.gov (United States)

    Speer, Rachel M; The, Therry; Xie, Hong; Liou, Louis; Adam, Rosalyn M; Wise, John Pierce

    2017-11-01

    Cobalt use is increasing particularly due to its use as one of the primary metals in cobalt-chromium-molybdenum (CoCrMo) metal-on-metal prosthetics. CoCrMo is a high-strength, wear-resistant alloy with reduced risk for prosthetic loosening and device fracture. More than 500,000 people receive hip implants each year in the USA which puts them at potential risk for exposure to metal ions and particles released by the prosthetic implants. Data show cobalt ions released from prosthetics reach the bloodstream and accumulate in the bladder. As patients with failed hip implants show increased urinary and blood cobalt levels, no studies have considered the effects of cobalt on human urothelial cells. Accordingly, we investigated the cytotoxic and genotoxic effects of particulate and soluble cobalt in urothelial cells. Exposure to both particulate and soluble cobalt resulted in a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ions. Based on intracellular cobalt ion levels, we found, when compared to particulate cobalt, soluble cobalt was more cytotoxic, but induced similar levels of genotoxicity. Interestingly, at similar intracellular cobalt ion concentrations, soluble cobalt induced cell cycle arrest indicated by a lack of metaphases not observed after particulate cobalt treatment. These data indicate that cobalt compounds are cytotoxic and genotoxic to human urothelial cells and solubility may play a key role in cobalt-induced toxicity.

  20. A spot test for detection of cobalt release - early experience and findings

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Menné, Torkil; Johansen, Jeanne D

    2010-01-01

    It is often difficult to establish clinical relevance of metal exposure in cobalt-allergic patients. Dermatologists and patients may incorrectly assume that many metallic items release cobalt at levels that may cause cobalt dermatitis. Cobalt-allergic patients may be unaware that they are exposed...

  1. Spin-dependent transport in cobalt nanocontacts

    Energy Technology Data Exchange (ETDEWEB)

    Sarau, G.

    2007-04-16

    The magnetoresistance response of cobalt nanocontacts with varying geometries formed between two extended electrodes has been experimentally investigated and linked to micromagnetic simulations. The contribution of the nanoconstriction to the measured magnetoresistance signal has been separated from that of the electrode bulk. The different nanocontact geometries exhibit different shape anisotropies resulting in a characteristic behavior of the magnetization at each nanocontact. The magnetization reversal processes are explained on the basis of the anisotropic magnetoresistance and domain wall scattering effects. The domain wall resistance takes positive values, which is in agreement with models based on the spin mistracking inside the domain wall. The 4 K MR measurements are found to be influenced by the exchange bias effect between the ferromagnetic cobalt electrodes and the antiferromagnetic oxidized Co surface. When cooling down in an applied magnetic field, the uniform biased Co layer behaves as if it possesses a unidirectional anisotropy axis along the field cooling direction. In the zero field cooling case, the exchange bias varies locally throughout the sample giving rise to non-reproducible successive MR traces. (orig.)

  2. Preparation and characterization of electrodeposited cobalt nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Irshad, M. I., E-mail: imrancssp@gmail.com; Mohamed, N. M., E-mail: noranimuti-mohamed@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 31750 PERAK (Malaysia); Ahmad, F., E-mail: faizahmad@petronas.com.my; Abdullah, M. Z., E-mail: zaki-abdullah@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 31750 PERAK (Malaysia)

    2014-10-24

    Electrochemical deposition technique has been used to deposit cobalt nanowires into the nano sized channels of Anodized Aluminium Oxide (AAO) templates. CoCl{sub 2}Ðœ‡6H2O salt solution was used, which was buffered with H{sub 3}BO{sub 3} and acidified by dilute H{sub 2}SO{sub 4} to increase the plating life and control pH of the solution. Thin film of copper around 150 nm thick on one side of AAO template coated by e-beam evaporation system served as cathode to create electrical contact. FESEM analysis shows that the as-deposited nanowires are highly aligned, parallel to one another and have high aspect ratio with a reasonably high pore-filing factor. The TEM results show that electrodeposited cobalt nanowires are crystalline in nature. The Hysteresis loop shows the magnetization properties for in and out of plane configuration. The in plane saturation magnetization (Ms) is lower than out of plane configuration because of the easy axis of magnetization is perpendicular to nanowire axis. These magnetic nanowires could be utilized for applications such as spintronic devices, high density magnetic storage, and magnetic sensor applications.

  3. Rare earth-cobalt permanent magnets

    International Nuclear Information System (INIS)

    Strnat, K.J.; Strnat, R.M.W.

    1991-01-01

    This paper reviews the historical background and the development of rare earth-cobalt-based permanent magnets from basic science studies on rare earth-transition metal alloys in the 1960's to today's broad spectrum of commercial magnet types and their applications. It puts the RE-Co magnetis in perspective relative to older magnet types and also traces the path to the subsequent development of the related Nd-Fe-B magnets. The treatment is qualitative, with emphasis on the relationship between fundamental properties of the compounds and the interaction between microstructure and magnetic domain walls that makes high coercivity and the exceptional hard magnetic properties of the rare-earth magnets possible. The various kinds of RE-Co magnets in production and use today, some of their engineering properties, and economic aspects governing their applicability, cost and availability are also discussed. Many references provide a guide to the special literature regarding the physics, metallurgy, manufacture, product selection and properties of rare earth-cobalt magnets. (orig.)

  4. Leather Contains Cobalt and Poses a Risk of Allergic Contact Dermatitis

    DEFF Research Database (Denmark)

    Hamann, Dathan; Hamann, Carsten R; Kishi, Patrick

    2016-01-01

    thirty-one leather swatches were screened for cobalt content/release with X-ray fluorescence (XRF) spectrometry and cobalt indicator solution (CIS). Samples with positive screens and 1 negative control were analyzed using inductively-coupled plasma mass spectrometry (ICPMS). RESULTS: CIS showed that 5...... of 131 samples contained cobalt, subsequently found to be between 1 and 190 parts per million (ppm) when evaluated with ICPMS. The XRF analysis showed that 6 samples contained >5% cobalt, subsequently found to contain greater than 300 ppm cobalt by ICPMS. 7 of 12 tested swatches contained cobalt...... in excess of 100 ppm. One sample contained greater than 1000 ppm cobalt. The prevalence of swatches containing cobalt at levels in excess of 190 ppm was at least 5% (n = 7; total, N = 131). DISCUSSION: Some leather consumer goods contain and release cobalt. Cobalt indicator solution is a poor screening test...

  5. Synthesis of cobalt boride nanoparticles using radio frequency thermal plasma

    International Nuclear Information System (INIS)

    Lapitan, Jr. Lorico DS.; Ying Ying Chen; Seesoek Choe; Watanabe, Takayuki

    2012-01-01

    Nano size cobalt boride particles were synthesized from vapor phase using a 30 kw-4 MHz radio frequency (RF) thermal plasma. Cobalt and boron powder mixtures used as precursors in different composition and feed rate were evaporated immediately in the high temperature plasma and cobalt boride nanoparticles were produced through the quenching process. The x-ray diffractometry (XRD) patterns of cobalt boride nanoparticles prepared from the feed powder ratio of 1:2 and 1:3 for Co: B showed peaks that are associated with the Co 2 B and CoB crystal phases of cobalt boride. The XRD analysis revealed that increasing the powder feed rate results in a higher mass fraction and a larger crystalline diameter of cobalt boride nanoparticles. The images obtained by field emission scanning electron microscopy (FE-SEM) revealed that cobalt boride nanoparticles have a spherical morphology. The crystallite size of the particles estimated with XRD was found to be 18-22 nm. (author)

  6. Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties.

    Science.gov (United States)

    Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

    2017-08-01

    This paper reports the synthesis, characterization, and electrochemical performance of nickel-cobalt hydroxide nanosheets. The hydroxide nanosheets of approximately 0.7nm thickness were prepared by delamination of layered nickel-cobalt hydroxide lactate in water and formed transparent colloids that were stable for months. The nanosheets were deposited on highly oriented pyrolytic graphite by spin coating, and their electrochemical behavior was investigated by cyclic voltammetry in potassium hydroxide electrolyte. Our method of electrode preparation allows for studying the electrochemistry of nanosheets where the majority of the active centers can participate in the charge transfer reaction. The observed electrochemical response was ascribed to mutual compensation of the cobalt and nickel response via electron sharing between these metals in the hydroxide nanosheets, a process that differentiates the behavior of nickel-cobalt hydroxide nanosheets from single nickel hydroxide or cobalt hydroxide nanosheets or their physical mixture. The presence of cobalt in the nickel-cobalt hydroxide nanosheets apparently decreases the time of electrochemical activation of the nanosheet layer, which for the nickel hydroxide nanosheets alone requires more potential sweeps. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Concentration of radioactive cobalt by seaweeds in the food chain

    International Nuclear Information System (INIS)

    Nakahara, Motokazu; Koyanagi, Taku; Saiki, Masamichi

    1976-01-01

    On the pathway of radioactive substances in marine environments, seaweeds play an important role because of their higher concentration factors for many radionuclides and because they constitute a link of food chain in the sea. In the present work, uptake, distribution and excretion of radioactive cobalt were studied on several kinds of seaweeds by radioisotope tracer experiments under laboratory conditions and concentration factors were calculated. The concentration factors were also estimated from the results of stable cobalt determination by activation analysis or atomic absorption spectrometry on seaweeds and seawater, and compared with the results of tracer expts. The seaweeds showed the species specificity for the concentration of stable and radioactive cobalt with diverse values of concentration factors and biological half-lives. The transfer of radioactive cobalt in the food chain from contaminated seaweeds to mollusca was examined by feeding abalones, Haliotis discus, with four kinds of seaweed labelled with 60 Co and observing retention. Absorption rate for radioactive cobalt by abalones calculated at two days after feeding showed diverse values depending upon the species of seaweed, as follows: 47% through Laminaria japonica and Ulva pertusa, 31% through Undaria pinnatifida and 26 through Eisenia bicyclis, respectively. From the results, it was assumed that the accumulation of radioactive cobalt by mollusca is affected by the species of seaweeds as food. A very high concentration of ingested radioactive cobalt in the midgut gland was seen on the autoradiograph of abalone samples. (auth.)

  8. Concentration of radioactive cobalt by seaweeds in the food chain

    International Nuclear Information System (INIS)

    Nakahara, M.; Koyanagi, T.; Saiki, M.

    1975-01-01

    On the pathway of radioactive substances in marine environments, seaweeds play an important role because of their higher concentration factors for many radionuclides and because they constitute a link in the food chain. In the present work, uptake, distribution and excretion of radioactive cobalt were studied on several kinds of seaweeds by radioisotope tracer experiments under laboratory conditions and concentration factors were calculated. The concentration factors were also estimated from the results of stable cobalt determination by activation analysis or atomic absorption spectrometry on seaweeds and seawater, and compared with the results of tracer experiments. The seaweeds showed the species specificity for the concentration of stable and radioactive cobalt with diverse values of concentration factors and biological half-lives. The transfer of radioactive cobalt in the food chain from contaminated seaweeds to mollusca was examined by feeding abalones, Haliotis discus, with four kinds of seaweed labelled with 60 Co and observing retention. Absorption rate for radioactive cobalt by abalones calculated at two days after feeding showed diverse values depending upon the species of seaweed, as follows: 47% through Laminaria japonica and Ulva pertusa, 31% through Undaria pinnatifida and 26% through Eisenia bicyclis, respectively. From the results, it was assumed that the accumulation of radioactive cobalt by mollusca is affected by the species of seaweeds as food. A very high concentration of ingested radioactive cobalt in the midgut gland was seen on the autoradiograph of abalone samples. (author)

  9. Incentives and opportunities for reducing the cobalt content in reactor core components

    International Nuclear Information System (INIS)

    Ocken, H.

    1985-01-01

    Cobalt in core components contributes to radiation field buildup on out-of-core surfaces. Core components containing cobalt-base alloys and cobalt as an impurity are identified. The use of cobalt-free wear-resistant alloys and construction materials with lower impurity levels of cobalt is disused. It is argued that such measures are cost effective. Lower radiation fields and disposal costs will offset higher raw material costs. Component performance will not be affected. (author)

  10. Hydroformylation of olefins with cobalt/phosphonate- and cobalt/sufonate-phosphines

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.; Kant, M. [Leibniz-Institut fuer Katalyse e.V., Berlin (Germany); Giuffrida, G.; Rosano, S. [Sasol Italy S.p.A., Paderno Dugnano (Italy)

    2006-07-01

    The hydroformylation of an industrial decene mixture with cobalt/phosphonate- and cobalt/sulfonate-phosphines used as catalysts was carried out. Highest aldehyde yield of ca. 60-65 mol% beside 2-5 mol% decane, 1-5 mol% decenes and 2-5 mol% of other oxoproducts was obtained at 170 C, 160-200 bar syngas pressure and a reaction time of 12-16 h. The reminder is a fraction of non-GC-detectable heavy oligomers (15-20 %). Best olefin conversion was reached with Ph{sub 2}P(p-C{sub 6}H{sub 4}-SO{sub 3}Li) and TPPTS as ligands, best stability of biphasic system with TPPTS and Ph{sub 2}P-(CH{sub 2}){sub 3}-SO{sub 3}Li. The terminal aldehyde selectivity amounted to 36-42 mol% of the aldehyde pool. (orig.)

  11. The effect of gaseous ammonia on cobalt perrhenate

    International Nuclear Information System (INIS)

    Maslov, L.P.; Men'shikov, O.D.; Borisov, V.V.; Sorokin, S.I.; Krutovertsev, S.A.; Kharkevich, S.I.; Ivanova, O.M.

    1994-01-01

    The influence of humid air ammonia mixture on crystal pentahydrate of cobalt(2) perrhenate has been studied by the methods of PES, IR spectroscopy thermal analysis and electrophysical measurements. It is shown that with an increase in ammonia content in gaseous phase cobalt perrhenate successively transforms into diaquodiammine-, tetrammine- and μ-dioxo-bis-(tetrammine) derivatives of cobalt. Reversibility of dioxocomplex formation and a correlation between the change in electrophysical properties of crystal sample and change in ammonia content in gaseous phase are pointed out. 16 refs.; 4 figs.; 1 tab

  12. Activation of cobalt 60 in the LVR-15 reactor core

    International Nuclear Information System (INIS)

    Melichar, F.

    1995-12-01

    Cobalt disks were irradiated in the LVR-15 reactor and the relevant cobalt-60 production parameters, particularly the formation rate, were measured. The data were compared with those from previous work by other authors and some discrepancies were found. It is concluded that additional experiments have to be performed in order to obtain reliable data, usable in economic balance assessment with respect to the use of hot chambers for the production of sealed cobalt-60 sources. (P.A.). 4 tabs., 3 refs., 10 annexes

  13. Sorption of cobalt on organic and inorganic intercalated clays

    International Nuclear Information System (INIS)

    Nava-Galve, G.; Pacheco, G.; Fetter, G.; Bulbulian, S.

    1996-01-01

    A Mexican montmorillonite clay was intercalated on the one hand with aluminium or zirconium polyhydroxications, and on the other with two organic compounds. Radioactive cobalt was used to study the Co 2+ sorption curves in the original and pillared clays. It was found that pillaring in general in does not favour the diffusion of cobalt between the layers specially the organic pillared clays. In equilibrium, the cobalt retention reached the highest level, around 0.7 meq/g in the Zr pillared clay. (author). 8 refs., 7 figs., 3 tabs

  14. Multiwalled Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    D. G. Larrude

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs synthesized by spray pyrolysis were decorated with cobalt oxide nanoparticles using a simple synthesis route. This wet chemistry method yielded nanoparticles randomly anchored to the surface of the nanotubes by decomposition of cobalt nitrate hexahydrate diluted in acetone. Electron microscopy analysis indicated that dispersed particles were formed on the MWCNTs walls. The average size increased with the increasing concentration of cobalt nitrate in acetone in the precursor mixture. TEM images indicated that nanoparticles were strongly attached to the tube walls. The Raman spectroscopy results suggested that the MWCNT structure was slightly damaged after the nanoparticle growth.

  15. The structural evolution and diffusion during the chemical transformation from cobalt to cobalt phosphide nanoparticles

    KAUST Repository

    Ha, Don-Hyung

    2011-01-01

    We report the structural evolution and the diffusion processes which occur during the phase transformation of nanoparticles (NPs), ε-Co to Co 2P to CoP, from a reaction with tri-n-octylphosphine (TOP). Extended X-ray absorption fine structure (EXAFS) investigations were used to elucidate the changes in the local structure of cobalt atoms which occur as the chemical transformation progresses. The lack of long-range order, spread in interatomic distances, and overall increase in mean-square disorder compared with bulk structure reveal the decrease in the NP\\'s structural order compared with bulk structure, which contributes to their deviation from bulk-like behavior. Results from EXAFS show both the Co2P and CoP phases contain excess Co. Results from EXAFS, transmission electron microscopy, X-ray diffraction, and density functional theory calculations reveal that the inward diffusion of phosphorus is more favorable at the beginning of the transformation from ε-Co to Co2P by forming an amorphous Co-P shell, while retaining a crystalline cobalt core. When the major phase of the sample turns to Co 2P, the diffusion processes reverse and cobalt atom out-diffusion is favored, leaving a hollow void, characteristic of the nanoscale Kirkendall effect. For the transformation from Co2P to CoP theory predicts an outward diffusion of cobalt while the anion lattice remains intact. In real samples, however, the Co-rich nanoparticles continue Kirkendall hollowing. Knowledge about the transformation method and structural properties provides a means to tailor the synthesis and composition of the NPs to facilitate their use in applications. © 2011 The Royal Society of Chemistry.

  16. Electrochemical performance of cobalt hydroxide nanosheets formed by the delamination of layered cobalt hydroxide in water

    Czech Academy of Sciences Publication Activity Database

    Schneiderová, Barbora; Demel, Jan; Pleštil, Josef; Tarábková, Hana; Bohuslav, Jan; Lang, Kamil

    2014-01-01

    Roč. 43, č. 27 (2014), s. 10484-10491 ISSN 1477-9226 R&D Projects: GA ČR GP13-09462P Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:61389013 Keywords : Ray- absorption spectroscopy * Alpha-cobalt * Solvothermal decomposition * Nickel * Nanocomposites Subject RIV: CA - Inorganic Chemistry; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.197, year: 2014

  17. The cobalt radioactive isotopes in environment; Les isotopes radioactifs du cobalt dans l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    For the year 1993 the total activity released in cobalt is 69 GBq for the whole of nuclear power plants. The part of activity in cobalt for La Hague in 1993 is 8 GBq of {sup 58}Co and 2 GBq of {sup 60}Co. The radioactive isotopes released by nuclear power plants or the reprocessing plant of La Hague under liquid effluents are shared by half between {sup 58}Co and {sup 60}Co. The exposure to sealed sources is the most important risk for the cobalt. The risk of acute exposure can associate a local irradiation of several decades of grays inducing a radiological burns, deep burn to treat in surgery by resection or graft even amputation. A global irradiation of organism for several grays induces an acute irradiation syndrome, often serious. At long term the stochastic effects are represented by leukemia and radio-induced cancers. The increase of probability of their occurrence is 1% by sievert. We must remind that the natural spontaneous probability is 25%. (N.C.)

  18. Mid-term survivorship and clinical outcomes of cobalt-chrome and oxidized zirconium on highly crosslinked polyethylene.

    Science.gov (United States)

    Petis, Stephen M; Vasarhelyi, Edward M; Lanting, Brent A; Howard, James L; Naudie, Douglas D R; Somerville, Lyndsay E; McCalden, Richard W

    2016-02-01

    The choice of bearing articulation for total hip arthroplasty in younger patients is amenable to debate. We compared mid-term patient-reported outcomes and survivorship across 2 different bearing articulations in a young patient cohort. We reviewed patients with cobalt-chrome or oxidized zirconium on highly crosslinked polyethylene who were followed prospectively between 2004 and 2012. Kaplan-Meier analysis was used to determine predicted cumulative survivorship at 5 years with all-cause and aseptic revisions as the outcome. We compared patient-reported outcomes, including the Harris hip score (HHS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Short-form 12 (SF-12) scores. A total of 622 patients were followed during the study period. Mean follow-up was 8.2 (range 2.0-10.6) years for cobalt-chrome and 7.8 (range 2.1-10.7) years for oxidized zirconium. Mean age was 54.9 ± 10.6 years for cobalt-chrome and 54.8 ± 10.7 years for oxidized zirconium. Implant survivorship was 96.0% (95% confidence interval [CI] 94.9%-97.1%) for cobalt-chrome and 98.7% (95% CI 98.0%-99.4%) for oxidized zirconium on highly crosslinked polyethylene for all-cause revisions, and 97.2% (95% CI 96.2%-98.2%) for cobalt-chrome and 99.0% (95% CI 98.4%-99.6%) for oxidized zirconium for aseptic revisions. An age-, sex- and diagnosis-matched comparison of the HHS, WOMAC and SF-12 scores demonstrated no significant changes in clinical outcomes across the groups. Both bearing surface couples demonstrated excellent mid-term survivorship and outcomes in young patient cohorts. Future analyses on wear and costs are warranted to elicit differences between the groups at long-term follow-up.

  19. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

    This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

  20. Surface magnetism in iron, cobalt, and nickel

    DEFF Research Database (Denmark)

    Alde´n, M.; Mirbt, S.; Skriver, Hans Lomholt

    1992-01-01

    with experimental values to within 10%, which may be considered most satisfactory in view of the computational efficiency of the Green’s function technique. Exchange and correlation have been treated wihtin the local spin-density approximation and we have considered three different parametrizations of the original......We have calculated magnetic moments, work functions, and surface energies for several of the most closely packed surfaces of iron, cobalt, and nickel by means of a spin-polarized Green’s-function technique based on the linear muffin-tin orbitals method within the tight-binding and atomic sphere...... approximations. We find enhanced spin moments at all the surfaces considered except for Ni fcc(111), where the moment at the surface reverts to its bulk value. This is in close agreement with earlier slab calculations. In addition, we find that the calculated work functions and surface energies agree...

  1. Ion exchange of Cobalt and Cadmium in Zeolite X

    International Nuclear Information System (INIS)

    Nava M, I.

    1994-01-01

    The growing development in the industry has an important contribution to the environmental damage, where the natural effluents are each day more contaminated by toxic elements, such as: mercury, chromium, lead and cadmium. So as to separate such elements it has sorbent must have enough stability, and have a sharp capacity of sorption. In this work it was studied the sorption behavior of cobalt and on the other hand, cadmium in aqueous solutions, which along with sodic form of the Zeolite X, undergoes a phenomenon of ionic interchange. Such interchange was verify to different concentration of cadmium, cobalt and hydronium ion. The content of cobalt and sodium in the interchanged samples was detected through the neutronic activation analysis. The results disclose a higher selectivity for cadmium than cobalt. (Author)

  2. NAMMA CARBON MONOXIDE BY ATTENUATED LASER TRANSMISSION (COBALT) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA COBALT dataset measures the carbon monoxide mixing ratio and derives carbon monoxide mixing ratio profiles in the upper troposphere/lower stratosphere...

  3. NAMMA CARBON MONOXIDE BY ATTENUATED LASER TRANSMISSION (COBALT) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA Carbon mOnoxide By Attenuated Laser Transmission (COBALT) dataset includes measurements of the carbon monoxide mixing ratio and derived carbon monoxide...

  4. Battery related cobalt and REE flows in WEEE treatment.

    Science.gov (United States)

    Sommer, P; Rotter, V S; Ueberschaar, M

    2015-11-01

    In batteries associated with waste electrical and electronic equipment (WEEE), battery systems can be found with a higher content of valuable and critical raw materials like cobalt and rare earth elements (REE) relative to the general mix of portable batteries. Based on a material flow model, this study estimates the flows of REE and cobalt associated to WEEE and the fate of these metals in the end-of-life systems. In 2011, approximately 40 Mg REE and 325 Mg cobalt were disposed of with WEEE-batteries. The end-of-life recycling rate for cobalt was 14%, for REE 0%. The volume of waste batteries can be expected to grow, but variation in the battery composition makes it difficult to forecast the future secondary raw material potential. Nevertheless, product specific treatment strategies ought to be implemented throughout the stages of the value chain. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Individually grown cobalt nanowires as magnetic force microscopy probes.

    Science.gov (United States)

    Alotaibi, Shuaa; Samba, Joshua; Pokharel, Sabin; Lan, Yucheng; Uradu, Kelechi; Afolabi, Ayodeji; Unlu, Ilyas; Basnet, Gobind; Aslan, Kadir; Flanders, Bret N; Lisfi, Abdellah; Ozturk, Birol

    2018-02-26

    AC electric fields were utilized in the growth of individual high-aspect ratio cobalt nanowires from simple salt solutions using the Directed Electrochemical Nanowire Assembly method. Nanowire diameters were tuned from the submicron scale to 40 nm by adjusting the AC voltage frequency and the growth solution concentration. The structural properties of the nanowires, including shape and crystallinity, were identified using electron microscopy. Hysteresis loops obtained along different directions of an individual nanowire using vibrating sample magnetometry showed that the magnetocrystalline anisotropy energy has the same order of magnitude as the shape anisotropy energy. Additionally, the saturation magnetization of an individual cobalt nanowire was estimated to be close to the bulk single crystal value. A small cobalt nanowire segment was grown from a conductive atomic force microscope cantilever tip that was utilized in magnetic force microscopy (MFM) imaging. The fabricated MFM tip provided moderate quality magnetic images of an iron-cobalt thin-film sample.

  6. Mixed alumina and cobalt containing plasma electrolytic oxide coatings

    Science.gov (United States)

    Yar-Mukhamedova, G. Sh; Ved', M. V.; Karakurkchi, A. V.; Sakhnenko, N. D.

    2017-06-01

    Principles of plasma electrolytic oxidation of the AL25 aluminum alloy in diphosphate alkali solutions containing cobalt(2+) cations are discussed. It has been established that a variation in the concentration of the electrolyte components provides the formation of mixed-oxide coatings consisting of the basic matrix materials and the cobalt oxides of different content. An increase in the cobalt oxide content in the coating is achieved by the variation in electrolysis current density as well as the treatment time due to both the electrochemical and thermo-chemical reactions at substrate surface and in spark region. Current density intervals that provide micro-globular surface formation and uniform cobalt distribution in the coating are determined. The composition and morphology of the surface causes high catalytic properties of synthesized materials, which confirmed the results of testing in model reaction CO and benzene oxidation as well as fuel combustion for various modes of engine operation.

  7. Cobalt(II) supported on ethylenediamine-functionalized ...

    Indian Academy of Sciences (India)

    nanocellulose; cobalt. 1. Introduction. Selective oxidation of alcohols to their corresponding carbonyl compounds is of significant importance in organic chemistry, both for fundamental research and industrial manufacturing. This transformation is tra-.

  8. Assessment of cobalt levels in wastewater, soil and vegetable ...

    African Journals Online (AJOL)

    carrot, lettuce, onion, spinach, cabbage, tomato and okra) samples collected on seasonal basis from January, 2013 to September 2014 along Kubanni stream channels in Zaria. The results show cobalt levels in wastewater were in the range of ...

  9. Pengaruh konsentrasi cobalt chromium pada uji hemolisis sebagai implan gigi

    Directory of Open Access Journals (Sweden)

    Yosaphat Bayu Rosanto

    2016-12-01

    Full Text Available The effect of concentration of cobalt chromium in hemolysis test for dental implant. Dental implants are used to replace tooth/teeth loss and its function. Cobalt chromium has ideal characteristics to be made as dental implants material. It is required that the material to be implanted must be biocompatible with cells and tissues. One of biocompatibility characteristics is hemocompatibility. Hemocompatibility of materials can be observed with hemolysis test. Thus the purpose of this research is to know whether cobalt chromium as dental implants material affect the hemolysis of rabbit blood or not. This research was done with rabbit blood (Oryctolagus cuniculus and devided into 3 groups (treatment, positive and negative control. The tested material was cobalt chromium Remanium® GM 800, a product from Dentaurum. The contact between blood and material was done with ASTM-F075 hemolysis test. Cobalt chromium was not hemolytic at 2,5%, 5%, and 10% of concentration, slightly hemolytic at 20% of concentration, and hemolytic at 40% and 80% of concentration. The conclusion of this research was variety of concentration of cobalt chromium affected hemolysis percentage signi cantly. ABSTRAK Implan gigi digunakan untuk mengganti gigi yang hilang untuk dan dapat mengembalikan fungsi gigi. Cobalt chromium memiliki sifat-sifat yang memenuhi persyaratan sebagai material implan. Material yang diimplankan dalam tubuh harus memiliki sifat biokompatibilitas. Salah satu sifat biokompatibilitas yang harus dimiliki material yang diimplankan dalam tubuh adalah sifat hemokompatibilitas. Sifat hemokompatibilitas dapat diketahui dengan uji hemolisis. Penelitian ini bertujuan untuk mengetahui ada/tidaknya pengaruh logam cobalt chromium sebagai material implan gigi terhadap hemolisis pada darah kelinci. Penelitian ini dilakukan menggunakan sampel darah yang didapat dari kelinci (Oryctolagus cuniculus yang dibagi menjadi 3 kelompok, yaitu perlakuan, kontrol

  10. Leaching refuse after sphalerite mineral for extraction zinc and cobalt

    Directory of Open Access Journals (Sweden)

    S. Brožová

    2016-07-01

    Full Text Available The paper deals with a possibility of zinc and cobalt extraction from refuse after sphalerite mineral leaching. It contains theoretic analysis of hydrometallurgical processes. Practical part describes samples and their leaching in 10 % and 20 % sulphuric acid. In the end of the paper it is evaluated under which conditions the highest yield of zinc and cobalt from refuse after sulphide ore leaching is reached.

  11. Infrared and Raman Spectroscopic Study of Carbon-Cobalt Composites

    OpenAIRE

    André Tembre; Jacques Hénocque; Martial Clin

    2011-01-01

    Analysis of carbon-cobalt thin films using infrared spectroscopy has shown existence of carbon-cobalt stretching mode and great porosity. The Raman spectroscopy and high-resolution transmission electron microscopy have been used in order to investigate the microstructure of the films. These films exhibit complex Raman spectra suggesting the presence of amorphous and crystallized phases. The different fractions of phases and the correlation between the atomic bond structures and the Raman feat...

  12. Recovery of cobalt and lithium fromspent Li-ion batteries

    OpenAIRE

    Busnardo, Natália Giovanini; Paulino, Jéssica Frontino; Afonso, Julio Carlos

    2007-01-01

    The "active mass" (cathode + anode + electrolyte) of spent Li-ion batteries was submitted to one of the following procedures: (a) it was calcined (500 ºC) and submitted to extraction with water to recover lithium salts. The residual solid was treated with sulfuric acid containing hydrogen peroxide. Cobalt was recovered as sulfate; (b) the "active mass" was treated with potassium hydrogen sulfate (500 ºC) and dissolved in water. Cobalt was precipitated together with copper after addition of so...

  13. Mechanizm of propylene oxidation on modified cobalt-molybdenum catalysts

    International Nuclear Information System (INIS)

    Kutyrev, M.Yu.; Rozentuller, B.V.; Isaev, O.V.; Margolis, L.Ya.; Krylov, O.V.

    1977-01-01

    Effect is studied of additions of iron, copper, nickel, and vanadium oxides, introduced into cobalt, molybdate, on oxidation reactions of propylene to acrolein and acrylicacid. The principal parameters determining the activity and selectivity of oxidation of propylene and acrolein on modified cobalt molibdate are the structure, the type of Mo-O bond, and the nature of the electron transitions in the solid under the effect of adsorption of the reaction components

  14. Synthesis and structural characterization of polyaniline/cobalt chloride composites

    Energy Technology Data Exchange (ETDEWEB)

    Asha, E-mail: arana5752@gmail.com [Department of Basic and Applied Sciences, Bhagat Phool Singh Mahilla Vishwavidyalaya, Khanpur Kalan, Sonipat-131305 (India); Goyal, Sneh Lata; Kishore, Nawal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001 (India)

    2016-05-23

    Polyaniline (PANI) and PANI /cobalt chloride composites were synthesized by in situ chemical oxidative polymerization of aniline with CoCl{sub 2}.6H{sub 2}O using ammonium peroxidisulphate as an oxidant. These composites were characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The XRD study reveals that both PANI and composites are amorphous. The XRD and SEM results confirm the presence of cobalt chloride in the composites.

  15. Nitrogen-doped carbon-supported cobalt-iron oxygen reduction catalyst

    Science.gov (United States)

    Zelenay, Piotr; Wu, Gang

    2014-04-29

    A Fe--Co hybrid catalyst for oxygen reaction reduction was prepared by a two part process. The first part involves reacting an ethyleneamine with a cobalt-containing precursor to form a cobalt-containing complex, combining the cobalt-containing complex with an electroconductive carbon supporting material, heating the cobalt-containing complex and carbon supporting material under conditions suitable to convert the cobalt-containing complex and carbon supporting material into a cobalt-containing catalyst support. The second part of the process involves polymerizing an aniline in the presence of said cobalt-containing catalyst support and an iron-containing compound under conditions suitable to form a supported, cobalt-containing, iron-bound polyaniline species, and subjecting said supported, cobalt-containing, iron bound polyaniline species to conditions suitable for producing a Fe--Co hybrid catalyst.

  16. Effects of cobalt in nickel-base superalloys

    Science.gov (United States)

    Tien, J. K.; Jarrett, R. N.

    1983-01-01

    The role of cobalt in a representative wrought nickel-base superalloy was determined. The results show cobalt affecting the solubility of elements in the gamma matrix, resulting in enhanced gamma' volume fraction, in the stabilization of MC-type carbides, and in the stabilization of sigma phase. In the particular alloy studied, these microstructural and microchemistry changes are insufficient in extent to impact on tensile strength, yield strength, and in the ductilities. Depending on the heat treatment, creep and stress rupture resistance can be cobalt sensitive. In the coarse grain, fully solutioned and aged condition, all of the alloy's 17% cobalt can be replaced by nickel without deleteriously affecting this resistance. In the fine grain, partially solutioned and aged condition, this resistance is deleteriously affected only when one-half or more of the initial cobalt content is removed. The structure and property results are discussed with respect to existing theories and with respect to other recent and earlier findings on the impact of cobalt, if any, on the performance of nickel-base superalloys.

  17. Cobalt Blues The Story of Leonard Grimmett, the Man Behind the First Cobalt-60 Unit in the United States

    CERN Document Server

    Almond, Peter R

    2013-01-01

    For the latter half of the 20th century, cobalt-60 units were the mainstay of radiation treatments for cancer. Cobalt Blues describes the development of the first cobalt-60 unit in the United States and the man behind it, Leonard Grimmett. Conceptually conceived before World War II, it only became possible because of the development of nuclear reactors during the war. Although Grimmett conceived of and published his ideas first, the Canadians built the first units because of the capability of their reactor to produce more suitable cobalt-60 sources. This book tells the story of how Grimmett and others came together at the time that the U S Atomic Energy Agency was pushing the use of radioactivity in medicine. Due to his sudden death, very little information about Grimmett was known until recently, when various documents have come to light, allowing the full story to be told.

  18. Cobalt mineral exploration and supply from 1995 through 2013

    Science.gov (United States)

    Wilburn, David R.

    2011-01-01

    The global mining industry has invested a large amount of capital in mineral exploration and development over the past 15 years in an effort to ensure that sufficient resources are available to meet future increases in demand for minerals. Exploration data have been used to identify specific sites where this investment has led to a significant contribution in global mineral supply of cobalt or where a significant increase in cobalt production capacity is anticipated in the next 5 years. This report provides an overview of the cobalt industry, factors affecting mineral supply, and circumstances surrounding the development, or lack thereof, of key mineral properties with the potential to affect mineral supply. Of the 48 sites with an effective production capacity of at least 1,000 metric tons per year of cobalt considered for this study, 3 producing sites underwent significant expansion during the study period, 10 exploration sites commenced production from 1995 through 2008, and 16 sites were expected to begin production by 2013 if planned development schedules are met. Cobalt supply is influenced by economic, environmental, political, and technological factors affecting exploration for and production of copper, nickel, and other metals as well as factors affecting the cobalt industry. Cobalt-rich nickel laterite deposits were discovered and developed in Australia and the South Pacific and improvements in laterite processing technology took place during the 1990s and early in the first decade of the 21st century when mining of copper-cobalt deposits in Congo (Kinshasa) was restricted because of regional conflict and lack of investment in that country's mining sector. There was also increased exploration for and greater importance placed on cobalt as a byproduct of nickel mining in Australia and Canada. The emergence of China as a major refined cobalt producer and consumer since 2007 has changed the pattern of demand for cobalt, particularly from Africa and

  19. Cobalt ferrite based magnetostrictive materials for magnetic stress sensor and actuator applications

    Science.gov (United States)

    Jiles, David C. (Inventor); Paulsen, Jason A. (Inventor); Snyder, John E. (Inventor); Lo, Chester C. H. (Inventor); Ring, Andrew P. (Inventor); Bormann, Keith A. (Inventor)

    2008-01-01

    Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals for iron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors and actuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.

  20. Magnetic Cobalt and Cobalt Oxide Nanoparticles in Hyperbranched Polyester Polyol Matrix

    Directory of Open Access Journals (Sweden)

    O. I. Medvedeva

    2017-01-01

    Full Text Available A series of cobalt (Co and its oxides based nanoparticles were synthesized by using hyperbranched polyester polyol Boltorn H20 as a platform and sodium borohydride as a reducing agent. UV, FT-IR, XRD, NTA, and TEM methods were employed to obtain physicochemical characteristics of the products. The average diameter of Co nanoparticles was approximately 8.2±3.4 nm. Their magnetic properties, including hysteresis loop, field-cooled, and zero field-cooled curves were investigated. The nanoparticles exhibit superparamagnetism at room temperature, accompanied by magnetic hysteresis below the blocking temperature.

  1. Gold-supported two-dimensional cobalt oxyhydroxide (CoOOH) and multilayer cobalt oxide islands

    DEFF Research Database (Denmark)

    Fester, Jakob; Walton, Alexander; Li, Zheshen

    2017-01-01

    morphology consisting of hydroxylated trilayer islands is identical to an exfoliated sheet of the [small beta]-CoOOH which is proposed to be the active phase of the cobalt oxide oxygen evolution reaction catalyst present in the electrochemical environment, and we note that this synthesized structure thus......In the present study, we investigate the facile conversion of Co-O bilayer islands on a Au(111) surface into preferentially O-Co-O trilayers in an oxygen atmosphere and O-Co-O-Co-O multilayers at elevated temperature. We characterize and compare the island morphologies with scanning tunneling...

  2. Tuning of magnetic parameters in cobalt-polystyrene nanocomposites by reduction cycling

    International Nuclear Information System (INIS)

    Nair, Swapna S.; Sunny, Vijutha; Anantharaman, M.R.

    2011-01-01

    Graphical abstract: Cobalt nanoparticles were prepared by a reduction process inside polymer pores. A porous polymer network (polystyrene) was chosen as the template for the synthesis of elementary cobalt as high surface area cobalt nanoparticles are prone to oxidation. The preliminary studies reveal that the cobalt is first formed with an oxide protective layer outside and upon repeating the reduction cycles, inner pores of the polymers are opened which enhanced the yield of metallic cobalt. These high surface area cobalt nanoparticles embedded in a polymer are ideal for the synthesis of carbon nanotubes as cobalt can act as a catalyst for the nanotube synthesis. The concentration of cobalt can be tuned in this technique by repeating the cycling process. Highlights: → Elementary cobalt nanoparticles were synthesized inside polystyrene by a novel process. → The self protection is achieved by the auto-shelling with the metal oxide. → The magnetisation and coercivity could be tuned by repeating the cycles. → Tuning of magnetic properties (both coercivity and magnetisation) could be achieved by the repetition of reduction cycles. → Synthesized nanocomposite can act as a catalyst for carbon nanotube synthesis. -- Abstract: Cobalt nanoparticles were prepared by a reduction process inside polymer pores using CoSO 4 .7H 2 O and NaBH 4 . A porous polymer network (sulphonated polystyrene) was chosen, as the template for the synthesis of elementary cobalt as high surface area cobalt nanoparticles are prone to oxidation. The preliminary studies reveal that the cobalt is first formed with an oxide protective layer outside and upon repeating the reduction cycles, inner pores of the polymers are opened which enhanced the yield of metallic cobalt. These high surface area cobalt nanoparticles embedded in a polymer are ideal for the synthesis of carbon nanotubes as cobalt can act as a catalyst for the nanotube synthesis. The concentration of cobalt can be tuned in this

  3. Cobalt 60 cation exchange with mexican clays

    International Nuclear Information System (INIS)

    Nava Galve, R.G.

    1993-01-01

    Mexican clays can be used to remove radioactive elements from contaminated aqueous solutions. Cation exchange experiments were performed with 60 Co radioactive solution. In the present work the effect of contact time on the sorption of Co 2+ was studied. The contact time in hydrated montmorillonite was from 5 to 120 minutes and in dehydrated montmorillonite 5 to 1400 minutes. The Co 2+ uptake value was, in hydrated montmorillonite, between 0.3 to 0.85 m eq/g and in dehydrated montmorillonite, between 0.6 to 1.40 m eq/g. The experiments were done in a pH 5.1 to 5.7 and normal conditions. XRD patterns were used to characterize the samples. The crystallinity was determined by X-ray Diffraction and it was maintained before and after the cation exchange. DTA thermo grams showed the temperatures of the lost humidity and crystallization water. Finally, was observed that dehydrated montmorillonite adsorb more cobalt than hydrated montmorillonite. (Author)

  4. Cobalt salen functionalised polycrystalline gold surfaces

    International Nuclear Information System (INIS)

    Raeisaenen, Minna T.; Almeida, Pedro de; Meinander, Kristoffer; Kemell, Marianna; Mutikainen, Ilpo; Leskelae, Markku; Repo, Timo

    2008-01-01

    The ability of N,N'-ethylene-bis(4-dodecyloxysalicylideneiminato)Co(II) (4) and literature known N,N'-ethylene-bis(3,5-di-t-butylsalicylideneiminato)Co(II) (5) to coordinate molecular oxygen was studied using ultraviolet-visible spectroscopy. For a comparison, the study was complemented with the archetype Co(II) salen (salen = N,N'-ethylene-bis(salicylideneamine)) complex. Especially 4, bearing long alkoxy chain substituents, coordinates dioxygen efficiently and reversibly, and therefore is an attractive candidate for further development of functional surfaces e.g. towards molecular level dioxygen sensors. In this respect, complexes 4 and 5 were attached on two different 4-pyridinethiol pre-treated polycrystalline Au surfaces. The changes in surface morphology after pyridinethiol and the complex treatment were studied with atomic force microscopy (AFM) measurements. Accordingly, with this method fairly smooth surfaces bearing cobalt(II) salen complexes can be prepared. In addition, the AFM results were complemented by X-ray reflection, cyclic voltammetry and wettability studies

  5. Water Adsorption on Free Cobalt Cluster Cations.

    Science.gov (United States)

    Kiawi, Denis M; Bakker, Joost M; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L B F M

    2015-11-05

    Cationic cobalt clusters complexed with water Con(+)-H2O (n = 6-20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200-1700 cm(-1) spectral range. All spectra exhibit a resonance close to the 1595 cm(-1) frequency of the free water bending vibration, indicating that the water molecule remains intact upon adsorption. For n = 6, the frequency of this band is blue-shifted, but it gradually converges to the free water value with increasing cluster size. In the lower-frequency range (200-650 cm(-1)) the spectra contain several bands which show a very regular frequency evolution, suggesting that the exact cluster geometry has little effect on the water-surface interaction. Density functional theory (DFT) calculations are carried out at the OPBE/TZP level for three representative sizes (n = 6, 9, 13) and indicate that the vibrations responsible for the resonances correspond to bending and torsional modes between the cluster and water moieties. The potential energy surfaces describing these interactions are very shallow, making the calculated harmonic frequencies and IR intensities very sensitive to small geometrical perturbations. We conclude that harmonic frequency calculations on (local) minima structures provide insufficient information for these types of cluster complexes and need to be complemented with calculations that provide a more extensive sampling of the potential energy surface.

  6. Adsorption, Bioaccumulation and Kinetics Parameters of the Phytoremediation of Cobalt from Wastewater Using Elodea canadensis.

    Science.gov (United States)

    Mosoarca, Giannin; Vancea, Cosmin; Popa, Simona; Boran, Sorina

    2018-05-01

    Present paper investigates the phytoremediation of cobalt from wastewaters using Elodea canadensis. Bioaccumulation tests were conducted at various concentrations of cobalt ranging from 1 to 15 mg/L. Final concentrations of cobalt in wastewaters, after phytoremediation, were less than 1 mg/L. E. canadensis' hyperaccumulator character with regard to cobalt is emphasised by the amount of cobalt retained: 0.39% ± 0.02% of dry mass at an initial concentration in wastewater of 15 mg/L. After 14 days of exposure to contaminant, the biomass as well as the relative growth rate has increased with the amount of cobalt in wastewaters, the plant manifesting an excellent tolerance to cobalt exposure. Adsorption of cobalt ions by E. canadensis can be well described by the Langmuir adsorption isotherm and the pseudo-second-order model equation.

  7. Monsoon induced cobalt enrichment in Porites (coral) from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.A.S.; Nath, B.N.

    Cobalt concentrations in growth bands of a reef building coral (Porites sp.) collected from Kalpeni Atoll of the Lakshadweep group of islands (Arabian Sea), rvealed that cobalt concentrations and Co/Ca ratios exhibit similar trend. Study indicates...

  8. Assessment of nickel and cobalt release from jewelry from a non-nickel directive country.

    Science.gov (United States)

    Boonchai, Waranya; Maneeprasopchoke, Pitchaya; Suiwongsa, Bordeesuda; Kasemsarn, Pranee

    2015-01-01

    A directive restricting nickel release from jewelry and other skin-contact products has not been initiated in Thailand or in the United States. The prevalence of nickel and cobalt allergies is increasing, and the main cause of sensitization seems to be jewelry. We aimed to investigate nickel and cobalt release from jewelry available in Thai marketplaces and to study the factors associated with nickel and cobalt release. Used costume jewelry items were collected from volunteers. They were tested with the dimethylglyoxime and cobalt tests. Five hundred fifty-one items, including belt buckles, bracelets, earrings, necklaces, rings, and watches, were tested; 216 (39.2%) gave positive dimethylglyoxime tests, and 206 (37.4%) gave positive cobalt tests. The factors that determined nickel or cobalt release were shopping location and jewelry price. Cobalt-containing jewelry could be identified by its dark color. A large proportion of the jewelry sold in Thai markets release nickel or cobalt.

  9. Electrosynthesis of highly transparent cobalt oxide water oxidation catalyst films from cobalt aminopolycarboxylate complexes.

    Science.gov (United States)

    Bonke, Shannon A; Wiechen, Mathias; Hocking, Rosalie K; Fang, Xi-Ya; Lupton, David W; MacFarlane, Douglas R; Spiccia, Leone

    2015-04-24

    Efficient catalysis of water oxidation represents one of the major challenges en route to efficient sunlight-driven water splitting. Cobalt oxides (CoOx ) have been widely investigated as water oxidation catalysts, although the incorporation of these materials into photoelectrochemical devices has been hindered by a lack of transparency. Herein, the electrosynthesis of transparent CoOx catalyst films is described by utilizing cobalt(II) aminopolycarboxylate complexes as precursors to the oxide. These complexes allow control over the deposition rate and morphology to enable the production of thin, catalytic CoOx films on a conductive substrate, which can be exploited in integrated photoelectrochemical devices. Notably, under a bias of 1.0 V (vs. Ag/AgCl), the film deposited from [Co(NTA)(OH2 )2 ](-) (NTA=nitrilotriacetate) decreased the transmission by only 10 % at λ=500 nm, but still generated >80 % of the water oxidation current produced by a [Co(OH2 )6 ](2+) -derived oxide film whose transmission was only 40 % at λ=500 nm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Contact dermatitis to cobalt chloride with an unusual mechanism.

    Science.gov (United States)

    Arslan, Sevket; Aksan, Serkan; Ucar, Ramazan; Caliskaner, Ahmet Zafer

    2015-10-01

    Contact dermatitis is a frequent inflammatory skin disease. A suspected diagnosis is based on clinical symptoms, a plausible contact to allergens and a suitable history of dermatitis. Therefore, careful diagnosis by patch testing is of great importance because the patch testing is important to find out which allergen/material causes the complaints. Metallic allergens such as cobalt are among the most common causes of allergic contact dermatitis, but frequencies of contact dermatitis to these allergens may vary in different skin areas. Here, we report an unusual case of cobalt allergy on the skin contact with the prosthetic leg of a 30-year-old female patient. The patient developed maculopapular and vesicular lesions on her contact region of residual limb to prosthetic leg. She underwent standard patch testing, which resulted in a strong positive reaction to cobalt chloride. This case report may serve to remind doctors to be aware of potential allergic reactions to prostheses and to enable them to recognize a metal allergy if it appears. Prosthetists should also be reminded of potential allergic reactions. Cobalt can be used as an accelerator in making a prosthetic socket. Several cases have been reported concerning allergies to components of the prosthetic socket. This is the first report of sensitization to cobalt which is used in making a prosthetic leg. © The International Society for Prosthetics and Orthotics 2014.

  11. Heating analysis of cobalt adjusters in reactor core

    International Nuclear Information System (INIS)

    Mei Qiliang; Li Kang; Fu Yaru

    2011-01-01

    In order to produce 60 Co source for industry and medicine applications in CANDU-6 reactor, the stainless steel adjusters were replaced with the cobalt adjusters. The cobalt rod will generate the heat when it is irradiated by neutron and γ ray. In addition, 59 Co will be activated and become 60 Co, the ray released due to 60 Co decay will be absorbed by adjusters, and then the adjusters will also generate the heat. So the heating rate of adjusters to be changed during normal operation must be studied, which will be provided as the input data for analyzing the temperature field of cobalt adjusters and the relative heat load of moderator. MCNP code was used to simulate whole core geometric configuration in detail, including reactor fuel, control rod, adjuster, coolant and moderator, and to analyze the heating rate of the stainless steel adjusters and the cobalt adjusters. The maximum heating rate of different cobalt adjuster based on above results will be provided for the steady thermal hydraulic and accident analysis, and make sure that the reactor is safe on the thermal hydraulic. (authors)

  12. Allergy risks with laptop computers - nickel and cobalt release.

    Science.gov (United States)

    Midander, Klara; Hurtig, Anna; Borg Tornberg, Anette; Julander, Anneli

    2016-06-01

    Laptop computers may release nickel and cobalt when they come into contact with skin. Few computer brands have been studied. To evaluate nickel and cobalt release from laptop computers belonging to several brands by using spot tests, and to quantify the release from one new computer by using artificial sweat solution. Nickel and cobalt spot tests were used on the lid and wrist supports of 31 laptop computers representing five brands. The same surfaces were tested on all computers. In addition, one new computer was bought and dismantled for release tests in artificial sweat according to the standard method described in EN1811. Thirty-nine per cent of the laptop computers were nickel spot test-positive, and 6% were positive for cobalt. The nickel on the surface could be worn off by consecutive spot testing of the same surface. The release test in artificial sweat of one computer showed that nickel and cobalt were released, although in low concentrations. As they constitute a potential source of skin exposure to metals, laptop computers should qualify as objects to be included within the restriction of nickel in REACH, following the definition of 'prolonged skin contact'. Skin contact resulting from laptop use may contribute to an accumulated skin dose of nickel that can be problematic for sensitized individuals. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Effect of Cobalt Supplementation on Performance of growing Calves

    Directory of Open Access Journals (Sweden)

    V.Nagabhushana

    Full Text Available The experiment was conducted to study the effect of critical supplementation of wheat straw with cobalt on fibre utilization and nutrient utilization in growing cross-bred male calves. Twenty-one crossbred (HF X Local male growing calves of 3-4 months age were fed with wheat straw based diet consisting without (Co0 and with 1 (Co1 and 6 (Co6 ppm cobalt as cobaltous chloride. There was no significant difference in intake of wheat straw, concentrate and DMI between the three groups and the ratio between concentrate and wheat straw was maintained at 40:60 irrespective of dietary level of cobalt. Similarly, average cumulative body weight, net gain in body weight or feed efficiency did not differ significantly between treatments. No significant effect was observed on the digestibility of dry matter, organic matter, crude protein, ether extract and fibre constituents like NDF, ADF, hemicellulose or cellulose by supplementation of 1 and 6 ppm Co to the diet of growing calves. Balance of nutrients such as Nitrogen, Calcium and Phosphorus was similar and positive in all the treatment groups. TDN and DCP values of the experimental diets remained almost similar irrespective of dietary level of cobalt. [Veterinary World 2008; 1(10.000: 299-302

  14. Effect of occupational exposure to cobalt blue dyes on the thyroid volume and function of female plate painters

    DEFF Research Database (Denmark)

    Prescott, E; Netterstrøm, B; Faber, J

    1992-01-01

    It has previously been shown that long-term oral exposure to cobalt can cause goiter and myxedema. The effect of industrial cobalt exposure on thyroid volume and function was determined for 61 female plate painters exposed to cobalt blue dyes in two Danish porcelain factories and 48 unexposed...... referents. Thyroid volume was determined by ultrasonography. The cobalt blue dyes were used in one of two forms, cobalt aluminate (insoluble) and cobalt-zinc silicate (semisoluble). Only the subjects exposed to semisoluble cobalt had a significantly increased urinary cobalt content (1.17 micrograms.mmol-1...... volume tended to be lower (P = 0.14). The group exposed to insoluble cobalt did not differ significantly in any thyroid-related parameters. No correlation between urinary cobalt and FT4I or thyroid volume was found. The study demonstrates an effect of cobalt on thyroid hormone metabolism....

  15. Importance of cobalt for individual trophic groups in an anaerobic methanol-degrading consortium.

    OpenAIRE

    Florencio, L; Field, J A; Lettinga, G

    1994-01-01

    Methanol is an important anaerobic substrate in industrial wastewater treatment and the natural environment. Previous studies indicate that cobalt greatly stimulates methane formation during anaerobic treatment of methanolic wastewaters. To evaluate the effect of cobalt in a mixed culture, a sludge with low background levels of cobalt was cultivated in an upflow anaerobic sludge blanket reactor. Specific inhibitors in batch assays were then utilized to study the effect of cobalt on the growth...

  16. Synthetic and mechanistic investigations of dioxygen activation on cobalt-Complexes

    OpenAIRE

    Müller, Jörg

    2011-01-01

    As described in Chapter 1, the cobalt(II) complex Bis[3-(salicylidenimino)-propyl]methylaminecobalt(II), [Co(salmdpt)] can bind dioxygen reversibly and forms a cobalt(III) superoxido complex during this process. One topic of the present work was the investigation of the dioxygen activation on cobalt complexes and the characterization of the dioxygen adduct complexes of the ligand saldptH2 and its derivatives. To synthesize the cobalt(III) superoxido complex of [Co(salmdpt)] different so...

  17. Allergic contact dermatitis caused by cobalt in leather – clinical cases

    DEFF Research Database (Denmark)

    Bregnbak, David; Opstrup, Morten S.; Jellesen, Morten Stendahl

    2017-01-01

    In 2013, we raised suspicion that cobalt in leather could be responsible for hitherto unrecognized cases of allergic contact dermatitis. We saw a patient sensitized only to cobalt with clear long-term exposure to cobalt from a leather sofa, and observed resolution of dermatitis following avoidanc...... swatches from furniture [3]. Here, we report 2 additional cases of allergic cobalt dermatitis caused by consumer leather exposure, to increase awareness about this topic....

  18. 40 CFR 421.310 - Applicability: Description of the secondary tungsten and cobalt subcategory.

    Science.gov (United States)

    2010-07-01

    ... secondary tungsten and cobalt subcategory. 421.310 Section 421.310 Protection of Environment ENVIRONMENTAL... CATEGORY Secondary Tungsten and Cobalt Subcategory § 421.310 Applicability: Description of the secondary tungsten and cobalt subcategory. The provisions of this subpart are applicable to discharges resulting from...

  19. 40 CFR 471.30 - Applicability; description of the nickel-cobalt forming subcategory.

    Science.gov (United States)

    2010-07-01

    ... nickel-cobalt forming subcategory. 471.30 Section 471.30 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Nickel-Cobalt Forming Subcategory § 471.30 Applicability; description of the nickel-cobalt forming subcategory. This subpart applies to discharges of pollutants to waters of the...

  20. Comparison of different supplemental cobalt forms on fiber digestion and cobalamin levels

    Science.gov (United States)

    Cobalt (Co) is essential for rumen microbial metabolism to synthesize methane, acetate and methionine. It also serves as a structural component of vitamin B*12, which functions as a coenzyme in energy metabolism. A study was conducted to determine if Co form (cobalt carbonate vs cobalt glucoheptona...

  1. Comparison of different supplemental cobalt forms on digestion and cobalamin levels

    Science.gov (United States)

    Cobalt (Co) is essential for rumen microbial metabolism to synthesize methane, acetate and methionine. It also serves as a structural component of vitamin B12, which functions as a coenzyme in energy metabolism. A study was conducted to determine if Co form (cobalt carbonate vs cobalt glucoheptonat...

  2. 75 FR 70583 - Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New Use Rule

    Science.gov (United States)

    2010-11-18

    ... 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New Use Rule AGENCY... chemical substance identified as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1), which was the..., subpart D. In accordance with 40 CFR 721.160(c)(3)(ii), EPA is withdrawing the rule issued for cobalt...

  3. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

  4. 40 CFR 421.230 - Applicability: Description of the primary nickel and cobalt subcategory.

    Science.gov (United States)

    2010-07-01

    ... primary nickel and cobalt subcategory. 421.230 Section 421.230 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Nickel and Cobalt Subcategory § 421.230 Applicability: Description of the primary nickel and cobalt subcategory. The provisions of this subpart are applicable to discharges resulting from the...

  5. 75 FR 70665 - Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide

    Science.gov (United States)

    2010-11-18

    ... Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide AGENCY: Environmental... as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1) which was the subject of... section 5(a)(2) of TSCA for the chemical substance identified as cobalt lithium manganese nickel oxide...

  6. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg. No...

  7. Open-shell nitrene- and carbene-complexes of cobalt : Characterisation and reactivity

    NARCIS (Netherlands)

    Goswami, M.

    2017-01-01

    Nitrene- and carbene-complexes of cobalt(II) porphyrins that are best described as porphyrin cobalt(III)-nitrene and carbene-radicals, respectively, are the key players in this thesis. Discrete spin transfer from the cobalt(II) metalloradical to the nitrene and carbene moiety induces interesting

  8. Tuning size and catalytic activity of nano-clusters of cobalt oxide

    Indian Academy of Sciences (India)

    Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were characterized before and after calcination by solvent extraction and the ...

  9. Cobalt allergy: suitable test concentration, and concomitant reactivity to nickel and chromium.

    Science.gov (United States)

    Lidén, Carola; Andersson, Niklas; Julander, Anneli; Matura, Mihály

    2016-06-01

    Cobalt allergy is frequent, but knowledge about exposure is limited. The patch test concentration and relevance of positive reactions are sometimes questioned. To assess the suitability of cobalt 1% versus 0.5% for patch testing, and to analyse the co-occurrence of allergy to cobalt, chromium, and nickel. Consecutive dermatitis patients (n = 656) were patch tested with cobalt chloride 0.5% and 1%, potassium dichromate 0.5%, and nickel sulfate 5%, all in petrolatum. Reactions were assessed on day (D)3, and on D6 or D7, and the reactivity and development of reactions were analysed. Allergy to any metal was shown in 31% of patients, allergy to cobalt in 14%, allergy to chromium in 7%, and allergy to nickel in 20%. A significant proportion (37%) of cobalt allergy cases were missed by cobalt 0.5% versus 1%, whereas the reactivity profiles were similar. Cobalt allergy was solitary, without concomitant allergy to chromium or nickel, in 50% of patients. Cobalt chloride 1% pet. is more suitable for patch testing than 0.5%. Solitary cobalt allergy is as frequent as concomitant allergy to cobalt and nickel or chromium. Sources of skin exposure to metals need to be identified for prevention of contact allergy. This is, owing to large knowledge gaps, particularly demanding for cobalt. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. A poly(pyrrole-Cobalt(II)deuteroporphyrin) electrode for the potentiometric determination of nitrite

    OpenAIRE

    Cosnier, Serge; Gondran, Chantal; Wessel, Rudolf; Montforts, Franz-Peter; Wedel, Michael

    2003-01-01

    The electrochemical properties of a new Co(II) deuteroporphyrin substituted by two electropolymerizable pyrrole groups has been investigated in organic solvent. This functionalization has allowed the preparation of the first example of a cobalt deuteroporphyrin film by oxidative electropolymerization. The resulting conducting polypyrrole film exhibits the regular electroactivity of cobalt deuteroporphyrin. Compared to conventional cobalt porphyrin electrochemistry, the replacement of porphyri...

  11. Hepatic lipidosis associated with cobalt deficiency in Omani goats.

    Science.gov (United States)

    Johnson, E H; Muirhead, D E; Annamalai, K; King, G J; Al-Busaidy, R; Hameed, M S

    1999-06-01

    Livers from 36 of 684 (5.3%) apparently healthy goats examined at an abattoir in the greater Muscat area of Oman exhibited gross pathological findings characterized by extremely pale, friable, fatty livers encompassing the entire organ. Histopathologically, diffuse hepatic lipidosis and occasional bile duct proliferation were observed. Periodic acid Schiff-positive, diastase-resistant pigment was observed in the macrophages lining the sinusoids. These histopathological lesions were consistent with those characteristic of ovine white liver disease. Cobalt analysis revealed that normal livers had six times more cobalt and a 3-fold less fat content than those measured in the fatty livers. This is the first report of an association between cobalt deficiency and hepatic lipidosis in Omani goats.

  12. Cobalt 60 gamma irradiation current status, trends and insights

    International Nuclear Information System (INIS)

    Corley, John T.

    1998-01-01

    This paper discusses the current status, trends and insights into the continued, safe use of cobalt 60 gamma irradiation. Also presented are some of the many initiatives undertaken at MDS Nordion. Topics covered include our investment for the future supply of raw materials and the latest news from source production. Briefly presented are the tasks associated with the safe transport of cobalt 60 around the world. Discussed is cobalt 60 usage at the customer site; more specifically maintaining source integrity, source utilization and irradiator design trends. Highlighted are industry trends for North America, Europe and the rest of the world. Finally presented are the challenges and opportunities for the industry. Stressed in the paper is the need to work together

  13. Activation of cobalt by neutrons from the Hiroshima bomb

    International Nuclear Information System (INIS)

    Kerr, G.D.; Dyer, F.F.; Emery, J.F.; Pace, J.V. III; Brodzinski, R.L.; Marcum, J.

    1990-02-01

    A study has been completed of cobalt activation in samples from two new locations in Hiroshima. The samples consisted of a piece of steel from a bridge located at a distance of about 1300 m from the hypocenter and pieces of both steel and concrete from a building located at approximately 700 m. The concrete was analyzed to obtain information needed to calculate the cobalt activation in the two steel samples. Close agreement was found between calculated and measured values for cobalt activation of the steel sample from the building at 700 m. It was found, however, that the measured values for the bridge sample at 1300 m were approximately twice the calculated values. Thus, the new results confirm the existence of a systematic error in the transport calculations for neutrons from the Hiroshima bomb. 52 refs., 32 figs., 16 tabs

  14. Effects of bathing on skin exposed to Cobalt-60 teletherapy

    International Nuclear Information System (INIS)

    Bohannan, P.A.

    1982-01-01

    The problem of this study was to determine the effects of bathing or not bathing on the degree of skin reaction occurring in patients receiving Cobalt-60 radiation therapy to the chest, back, or head and neck. A quasi experimental study was done using a 2 x 7 repeated measures design. Sixty-seven subjects receiving Cobalt-60 radiation therapy at the Moncrief Radiation Center in Fort Worth, Texas, were randomly assigned to an experimental group who did not bathe during therapy and a control group who did bathe with water during therapy. Observations were made after each 1000 rads of therapy and two weeks after the final treatment. Erythema and pigmentation measurements were taken using the Photovolt 670 and rates were assigned using the Baker-Leith Rating Scale. Findings from the study suggest that bathing the portal of entry with water during the treatment period does not influence the degree of skin response that occurs from Cobalt-60 teletherapy

  15. New avenues in cobalt-60 production at Ontario Hydro

    International Nuclear Information System (INIS)

    Mylvaganam, C.K.; Ronchka, R.A.

    1990-01-01

    Ontario Hydro produces cobalt-60 in the control rods of twelve power reactors. These reactors have a typical flux of 2 x 10 14 neutrons/cm 2 /s, making them efficient producers of cobalt-60. Current annual production is 45 million curies. Since the primary function of these reactors is the production of electricity, their flexibility to meet the needs of commercial cobalt production by the control rod route is limited. Ontario Hydro is therefore developing innovative production techniques, making use of the CANDU reactor's unique ability to be fuelled on-power. These techniques will enable production to better respond to the market's requirements for quantity and specific activity. As it is supplementary to control rod production, annual supply could potentially reach 165 million curies. (author)

  16. C-188 cobalt-60 sealed source integrity: source monitoring

    International Nuclear Information System (INIS)

    Defalco, G.M.; Shah, V.

    1995-01-01

    The integrity of C-188 cobalt-60 sealed sources used for radiation processing will be a key factor in the continued industrial acceptance and growth of gamma irradiation technology. Given the public's relatively poor understanding of most nuclear topics and the news media's tendency to sensationalize events, it is appropriate for suppliers and users of gamma technology to be vigilant and conservative regarding the application of cobalt-60 sources to industrial purposes. Nordion's recent decision to extend the optional warranty on its C-188 cobalt-60 sealed source from 15 years to 20 years is based on over 30 years of data generated from its on-going SOURCE SURVEILLANCE PROGRAM. This paper presents an overview of the C-188 SOURCE SURVEILLANCE PROGRAM. (author)

  17. Regression of posterior uveal melanomas following cobalt-60 plaque radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Cruess, A.F.; Augsburger, J.J.; Shields, J.A.; Brady, L.W.; Markoe, A.M.; Day, J.L.

    1984-12-01

    A method has been devised for evaluating the rate and extent of regression of the first 100 consecutive patients with a posterior uveal melanoma that had been managed by Cobalt-60 plaque radiotherapy at Wills Eye Hospital. It was found that the average posterior uveal melanoma in the series did not regress rapidly to a flat, depigmented scar but shrank slowly and persisted as a residual mass approximately 50% of the thickness of the original tumor at 54 months following Cobalt-60 plaque radiotherapy. The authors also found that the rate and extent of regression of the tumors in patients who subsequently developed metastatic melanoma were not appreciably different from the rate and extent of regression of the tumors in patients who remained well systemically. These observations indicate that the rate and extent of regression of posterior uveal melanomas following Cobalt-60 plaque radiotherapy are poor indicators of the prognosis of the affected patients for subsequent development of clinical metastatic disease.

  18. Thermal transport in cuprates, cobaltates, and manganites

    Energy Technology Data Exchange (ETDEWEB)

    Berggold, K.

    2006-09-15

    The subject of this thesis is the investigation of the thermal transport properties of three classes of transition-metal oxides: Cuprates, cobaltates, and manganites. The layered cuprates R{sub 2}CuO{sub 4} with R=La, Pr, Nd, Sm, Eu, and Gd show an anomalous thermal conductivity {kappa}. Two maxima of {kappa} are observed as a function of temperature for a heat current within the CuO{sub 2} planes, whereas for a heat current perpendicular to the CuO{sub 2} planes only a conventional phononic low-temperature maximum of {kappa} is present. Evidence is provided that the high-temperature maximum is caused by heat-carrying excitations on the CuO{sub 2} square lattice. Moreover, it is shown that the complex low-temperature and magnetic-field behavior of {kappa} in Nd{sub 2}CuO{sub 4} is most likely caused by additional phonon scattering rather than by heat-carrying Nd magnons, as it was proposed in the literature. In the cobaltates RCoO{sub 3} with R=La, Pr, Nd, and Eu, a temperature-induced spin-state transition of the Co{sup 3+} ions occurs. It is shown that the additional lattice disorder caused by the random distribution of populated higher spin states causes a large suppression of the thermal conductivity of LaCoO{sub 3} for T>25 K. The effect is much weaker in PrCoO{sub 3} and NdCoO{sub 3} due to the increased spin gap. A quantitative analysis of the responsible mechanisms based on EuCoO{sub 3} as a reference compound is provided. A main result is that the static disorder is sufficient to explain the suppression of {kappa}. No dynamical Jahn-Teller distortion, as proposed in the literature, is necessary to enhance the scattering strength. Below 25 K, k is mainly determined by resonant phonon scattering on paramagnetic impurity levels, e.g. caused by oxygen non-stoichiometry. Such a suppression of the thermal conductivity by resonant scattering processes is e.g. known from Holmium ethylsulfate. This effect is most pronounced in LaCoO{sub 3}, presumably due to

  19. Thermal transport in cuprates, cobaltates, and manganites

    International Nuclear Information System (INIS)

    Berggold, K.

    2006-09-01

    The subject of this thesis is the investigation of the thermal transport properties of three classes of transition-metal oxides: Cuprates, cobaltates, and manganites. The layered cuprates R 2 CuO 4 with R=La, Pr, Nd, Sm, Eu, and Gd show an anomalous thermal conductivity κ. Two maxima of κ are observed as a function of temperature for a heat current within the CuO 2 planes, whereas for a heat current perpendicular to the CuO 2 planes only a conventional phononic low-temperature maximum of κ is present. Evidence is provided that the high-temperature maximum is caused by heat-carrying excitations on the CuO 2 square lattice. Moreover, it is shown that the complex low-temperature and magnetic-field behavior of κ in Nd 2 CuO 4 is most likely caused by additional phonon scattering rather than by heat-carrying Nd magnons, as it was proposed in the literature. In the cobaltates RCoO 3 with R=La, Pr, Nd, and Eu, a temperature-induced spin-state transition of the Co 3+ ions occurs. It is shown that the additional lattice disorder caused by the random distribution of populated higher spin states causes a large suppression of the thermal conductivity of LaCoO 3 for T>25 K. The effect is much weaker in PrCoO 3 and NdCoO 3 due to the increased spin gap. A quantitative analysis of the responsible mechanisms based on EuCoO 3 as a reference compound is provided. A main result is that the static disorder is sufficient to explain the suppression of κ. No dynamical Jahn-Teller distortion, as proposed in the literature, is necessary to enhance the scattering strength. Below 25 K, k is mainly determined by resonant phonon scattering on paramagnetic impurity levels, e.g. caused by oxygen non-stoichiometry. Such a suppression of the thermal conductivity by resonant scattering processes is e.g. known from Holmium ethylsulfate. This effect is most pronounced in LaCoO 3 , presumably due to magnetic polaron formation. In the doped compounds La 1-x Sr x CoO 3 with 0≤x≤0.25, a large

  20. Sulfidation behavior of rhenium and cobalt-rhenium alloys

    International Nuclear Information System (INIS)

    Shiring, R.; Douglass, D.L.

    1999-01-01

    The sulfidation behavior of Re and three Co-Re alloys, 15, 30, and 45 w/o, was studied over the temperature range 700--800 C at sulfur pressures of 10 -4 and 10 -2 atm. The kinetics of sulfidation followed the parabolic rate law and the activation energies for all alloys were similar to that of pure cobalt. A positive rate dependency on sulfur pressure was observed and Pt markers were located at the metal-scale interface, both observations clearly suggesting that outward cation diffusion through a P-type sulfide scale occurred. Two dominant sulfides, Co 9 S 8 and ReS 2 , formed. Weight gains decreased for a given set of conditions with increasing rhenium content. An order of magnitude decrease in the sulfidation rate occurred as the rhenium content increased from 15 to 45 w/o. Preferential sulfidation of cobalt initially occurred, causing a rhenium-enriched zone to form in the substrate beneath the cobalt-sulfide scale. The initial sulfide to form was Co 3 S 4 , but, subsequently, Co 9 S 8 became the dominant sulfide, forming beneath the outer Co 3 S 4 layer. ReS 2 formed at lower cobalt levels. Pure Re was also studied, the sulfidation rate being about 10 4 times slower than that of cobalt. The decreasing rate of sulfidation with increasing Re content is attributed primarily to slower cobalt diffusion outward through the Re-enriched substrate, a phenomenon similar to that observed by C. Wagner for the oxidation of Ni-Pt alloys

  1. Hydrogen evolution catalyzed by cobalt diimine-dioxime complexes.

    Science.gov (United States)

    Kaeffer, Nicolas; Chavarot-Kerlidou, Murielle; Artero, Vincent

    2015-05-19

    Mimicking photosynthesis and producing solar fuels is an appealing way to store the huge amount of renewable energy from the sun in a durable and sustainable way. Hydrogen production through water splitting has been set as a first-ranking target for artificial photosynthesis. Pursuing that goal requires the development of efficient and stable catalytic systems, only based on earth abundant elements, for the reduction of protons from water to molecular hydrogen. Cobalt complexes based on glyoxime ligands, called cobaloximes, emerged 10 years ago as a first generation of such catalysts. They are now widely utilized for the construction of photocatalytic systems for hydrogen evolution. In this Account, we describe our contribution to the development of a second generation of catalysts, cobalt diimine-dioxime complexes. While displaying similar catalytic activities as cobaloximes, these catalysts prove more stable against hydrolysis under strongly acidic conditions thanks to the tetradentate nature of the diimine-dioxime ligand. Importantly, H2 evolution proceeds via proton-coupled electron transfer steps involving the oxime bridge as a protonation site, reproducing the mechanism at play in the active sites of hydrogenase enzymes. This feature allows H2 to be evolved at modest overpotentials, that is, close to the thermodynamic equilibrium over a wide range of acid-base conditions in nonaqueous solutions. Derivatization of the diimine-dioxime ligand at the hydrocarbon chain linking the two imine functions enables the covalent grafting of the complex onto electrode surfaces in a more convenient manner than for the parent bis-bidentate cobaloximes. Accordingly, we attached diimine-dioxime cobalt catalysts onto carbon nanotubes and demonstrated the catalytic activity of the resulting molecular-based electrode for hydrogen evolution from aqueous acetate buffer. The stability of immobilized catalysts was found to be orders of magnitude higher than that of catalysts in the

  2. Characterization of Cobalt F-75 powder for biomedical application

    International Nuclear Information System (INIS)

    Zuraidawani, C.D.; Shamsul, J.B.; Fazlul, B.; Nur Hidayah, A.Z.

    2007-01-01

    Cobalt F-75 alloys is commonly used for surgical implants because of their strength, corrosion resistance, non-magnetic behaviour and biocompatibility. In this paper, gas atomized of Cobalt F-75 powders were selected for evaluation. These powders supplied by Sandvik Osprey Ltd. The characteristics of these powders were investigated by using particle size analysis, X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscope (SEM). Two different powder sizes (8.8 μm and 11.5 μm) have showed spherical morphology and the value of densities are 7.9 and 7.6 g/cm 3 respectively. (author)

  3. Investigation of the production of cobalt-60 via particle accelerator

    Directory of Open Access Journals (Sweden)

    Artun Ozan

    2017-01-01

    Full Text Available The production process of cobalt-60 was simulated by a particle accelerator in the energy range of 5 to 100 MeV, particle beam current of 1 mA, and irradiation time of 1 hour to perform yield, activity of reaction, and integral yield for charged particle-induced reactions. Based on nuclear reaction processes, the obtained results in the production process of cobalt-60 were also discussed in detail to determine appropriate target material, optimum energy ranges, and suitable reactions.

  4. Photocatalytic degradation of congo red using copper substituted cobalt ferrite

    Science.gov (United States)

    Kirankumar, V. S.; Hardik, B.; Sumathi, S.

    2017-11-01

    Co1-xCuxFe2O4 nanoparticles with x = 0 and 0.5 were synthesized through the combustion method. The as-made materials are face centered-cubic close-packed spinel structures. The characterization techniques such as powder XRD, FTIR, UV-DRS and SEM studies collectively verified that the formed products are cobalt ferrite and copper substituted cobalt ferrite nanoparticles. In addition, the mean crystalline size, lattice parameter and band gap energy of nanoparticles are calculated. The photocatalytic activity of the obtained Co1-xCuxFe2O4 spinel nanoparticles is evaluated by monitoring the degradation of congo red under visible light irradiation.

  5. Cobalt-60 gamma radiation effects on degradation of pesticides used in stored rice and beans; Efeitos da radiacao gama do cobalto-60 na degradacao de inseticidas aplicados em arroz e feijao armazenados

    Energy Technology Data Exchange (ETDEWEB)

    Groppo, Gerson A.

    1988-02-01

    The present work, carried out at CENA, an agriculture nuclear energy center - University of Sao Paulo - Brazil, investigates the Cobalt-60 gamma radiation effects on insecticides applied to stored rice and beans. The radiation dose applied - 200 Gy - to the stored rice and beans treated with insecticides was not sufficient to cause a noticeable chemical degradation through insect mortality. (author). 31 refs., 23 tabs.

  6. Elicitation threshold of cobalt chloride: analysis of patch test dose-response studies.

    Science.gov (United States)

    Fischer, Louise A; Johansen, Jeanne D; Voelund, Aage; Lidén, Carola; Julander, Anneli; Midander, Klara; Menné, Torkil; Thyssen, Jacob P

    2016-02-01

    Cobalt is a strong skin sensitizer (grade 5 of 5 in the guinea-pig maximization test) that is used in various industrial and consumer applications. To prevent sensitization to cobalt and elicitation of allergic cobalt dermatitis, information about the elicitation threshold level of cobalt is important. To identify the dermatitis elicitation threshold levels in cobalt-allergic individuals. Published patch test dose-response studies were reviewed to determine the elicitation dose (ED) levels in dermatitis patients with a previous positive patch test reaction to cobalt. A logistic dose-response model was applied to data collected from the published literature to estimate ED values. The 95% confidence interval (CI) for the ratio of mean doses that can elicit a reaction in 10% (ED(10)) of a population was calculated with Fieller's method. On the basis of five included studies, the ED10 values of aqueous cobalt chloride ranged between 0.0663 and 1.95 µg cobalt/cm(2), corresponding to 30.8-259 ppm. Our analysis provides an overview of the doses of cobalt that are required to elicit allergic cobalt contactdermatitis in sensitized individuals, and thereby the basis for future prevention of cobalt allergy. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Heating-induced inner-sphere substitution and reduction-oxidation reactions of the solid phenanthroline containing cobalt (2) and cobalt (3) complexes

    International Nuclear Information System (INIS)

    Palade, D.M.

    1996-01-01

    The results of the differential thermal and thermogravimetric analyses of solid phenanthroline-containing complexes of cobalt (2) and cobalt (3) in the atmosphere of the air have been analyzed. Mechanism of redox reactions occurring when cobalt (3) complexes are heated has been discussed. It is shown that some of gaseous products of the redox processes appear as a result of secondary reactions and not the processes of the ligands oxidation by Co 3+ . The influence of certain inner-sphere and coordinated anions (of I, inclusively) on cobalt (3) complexes behaviour during heating has been considered

  8. Neodymium cobalt oxide as a chemical sensor

    Science.gov (United States)

    Abdel-Latif, I. A.; Rahman, Mohammed M.; Khan, Sher Bahadar

    2018-03-01

    Chemical sensing and electrical transport properties of neodymium coblate, NdCoO3, was investigated in this work. It was prepared by using co-precipitation method. Pure neodymium chloride and cobalt chloride were mixing in the presence of sodium hydroxide and the obtained co-precipitated powder was calcined at 850 and 1000 °C. The synthesized composites, as-grown (NdCoO3-I), calcined at 850 °C (NdCoO3-II), and calcined at 1000 °C (NdCoO3-III) were studied in details in terms of their morphological and structural properties. The X-ray analysis confirmed that the synthesized products are well crystalline possessing single phase orthorhombic crystal system of space group Pbnm(62). The crystallite size of NdCoO3-I, NdCoO3-II, and NdCoO3-III is 22, 111, and 338 nm, respectively which reflect that crystallite size is increasing with increase in firing temperature. The DC resistivity was measured as a function of temperature in the temperature range from room temperature up to 200 °C. All NdCoO3 are semiconductor in this range of temperature but showed different activation energy which strongly depends on the crystallite size of the products. The activation energy decreased with increase in crystallite size, 0.798, 0.414 and 0.371 eV for NdCoO3-I, NdCoO3-II, and NdCoO3-III, respectively. Thus resistivity increases with increase in crystallite size of NdCoO3. All NdCoO3 products were tested as chemical sensor for acetone by electrochemical approaches and showed excellent sensitivity. Among the NdCoO3 samples, NdCoO3-III showed the highest sensitivity (3.4722 μAcm-2 mM-1) compared to other compositions and gradually decreased to 3.2407 μAcm-2 mM-1 with decreasing the crystallite size of NdCoO3-II. It is also observed that the sensitivity drastically decreased to 0.76253 μAcm-2 mM-1 in the case of NdCoO3-I. It is introduced an efficient route for the detection of environmental unsafe chemicals by electrochemical approach for the safety of healthcare and environmental

  9. Ternary complexes of cobalt cysteinylglycine with histidylserine and ...

    Indian Academy of Sciences (India)

    Interaction of cobalt cysteinylglycine with histidylserine and histidylphenylalanine was investigated in a 1 : 1 : 1 ratio at 35°C and 0.10 mol dm-3 ionic strength. Their stabilities and geometries were determined. Their DNA binding and cleavage properties were investigated. The intrinsic binding constants () for DNA bound ...

  10. Controlled free radical polymerization of vinyl acetate with cobalt ...

    Indian Academy of Sciences (India)

    able processes but also to the hydrolysis of environmen- tally friendly polyvinyl alcohol in the film formations, separation and bioprocesses, or coatings (figure 4). 4. Conclusion. The cobalt-mediated controlled radical polymerization of vinyl acetate was studied in bulk. It indicated a faster rate than solution polymerization.

  11. Cobalt extraction in ammoniacal solution: Electrochemical effect of metallic iron

    Science.gov (United States)

    Osseo-Asare, K.; Lee, J. W.; Kim, H. S.; Pickering, H. W.

    1983-12-01

    The dissolution behavior of iron and cobalt in ammoniacal ammonium carbonate solution has been investigated with the aid of Eh-pH diagrams for the Fe-NH3-H2O-CO3 and Co-NH3-H2O-CO3 systems, and electrochemical techniques such as open circuit potential measurements and potentiostatic and potentiodynamic polarization experiments. The polarization measurements indicate that both Fe and Co electrodes show active and passive behavior, and that Co dissolves at a more oxidizing potential than does Fe (e.g., E = -0.34 V (SHE) for Co and E = -0.52 V for Fe at a dissolution rate of 1 mA cm-2). The active and passive current densities for Co are both greater than for Fe. In sintered Fe-Co mixtures, the presence of Fe shifts the potential of the maximum current to less noble values and also lowers the magnitude of this current. In addition there is practically no cobalt dissolution when the potential exceeds 0.6 V (SHE). It is suggested that the well-known poor recovery of cobalt from reductive-roasted ferruginous oxide ores may be partly related to the dissolution behavior of a metallic alloy phase containing both iron and cobalt.

  12. Cobalt nanoparticles as reusable catalysts for reduction of 4 ...

    Indian Academy of Sciences (India)

    33

    active and ordered structures of cobalt nanoparticles. The air stable ... same surfactant was found to reduce p-nitrophenol but lose their catalytic efficiency after recovery. Based on chemical and ... industrial sources.11-13 The US Environmental Protection Agency has reported nitrophenols as one of the most hazardous and ...

  13. Preparation and characterization of zinc and cobalt (II, III) oxides ...

    Indian Academy of Sciences (India)

    Abstract. The decolourization of the direct red 23 diazo dye, commonly used in textile industries, was investi- gated through the heterogeneous photocatalysis mediated by zinc oxide, n-type semiconductor combined with p-type cobalt oxide at 30◦C. The mixture of n- and p-type semiconductors may form a p–n junction, ...

  14. Bioavailability of cobalt, zinc and selenium and anthelmintic effects ...

    African Journals Online (AJOL)

    The present study was carried out to compare the use of liver and plasma analysis as methods of assessing the status of cobalt, zinc and selenium in sheep, and to assess the anthelmintic efficacy of fortified and non-fortified albendazole preparations. Plasma and liver samples were collected in duplicate from fourteen ...

  15. Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application.

    Science.gov (United States)

    Kulanthaivel, Senthilguru; Roy, Bibhas; Agarwal, Tarun; Giri, Supratim; Pramanik, Krishna; Pal, Kunal; Ray, Sirsendu S; Maiti, Tapas K; Banerjee, Indranil

    2016-01-01

    The present study delineates the synthesis and characterization of cobalt doped proangiogenic-osteogenic hydroxyapatite. Hydroxyapatite samples, doped with varying concentrations of bivalent cobalt (Co(2+)) were prepared by the ammoniacal precipitation method and the extent of doping was measured by ICP-OES. The crystalline structure of the doped hydroxyapatite samples was confirmed by XRD and FTIR studies. Analysis pertaining to the effect of doped hydroxyapatite on cell cycle progression and proliferation of MG-63 cells revealed that the doping of cobalt supported the cell viability and proliferation up to a threshold limit. Furthermore, such level of doping also induced differentiation of the bone cells, which was evident from the higher expression of differentiation markers (Runx2 and Osterix) and better nodule formation (SEM study). Western blot analysis in conjugation with ELISA study confirmed that the doped HAp samples significantly increased the expression of HIF-1α and VEGF in MG-63 cells. The analysis described here confirms the proangiogenic-osteogenic properties of the cobalt doped hydroxyapatite and indicates its potential application in bone tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Molecular structure and DFT investigations on new cobalt(II ...

    Indian Academy of Sciences (India)

    Sci. Vol. 127, No. 12, December 2015, pp. 2137–2149. c Indian Academy of Sciences. DOI 10.1007/s12039-015-0976-x. Molecular structure and DFT investigations on new cobalt(II) chloride complex with superbase guanidine type ligand. SAIED M SOLIMANa,b,∗, MORSY A M ABU-YOUSSEFb,∗. , JΦRG ALBERINGc and.

  17. Advanced alloy design technique: High temperature cobalt base superalloy

    Science.gov (United States)

    Dreshfield, R. L.; Freche, J. C.; Sandrock, G. D.

    1972-01-01

    Advanced alloy design technique was developed for treating alloys that will have extended life in service at high temperature and intermediate temperatures. Process stabilizes microstructure of the alloy by designing it so that compound identified with embrittlement is eliminated or minimized. Design process is being used to develop both nickel and cobalt-base superalloys.

  18. Making a robust carbon-cobalt(III) bond

    DEFF Research Database (Denmark)

    Larsen, Erik; Madsen, Anders Østergaard; Kofod, Pauli

    2009-01-01

    The coordination ion with a well-characterized carbon-cobalt(III) bond, the (1,4,7-triazacyclononane)(1,6-diamino-3-thia-4-hexanido)cobalt(III) dication, [Co(tacn)(C-aeaps)](2+) (aeaps, for aminoethylaminopropylsulfide), has been reacted with iodomethane, and the S-methyl thionium derivative has...... cobalt(III) for the three involved coordination ions are compared to those computed from DFT with different standard choices for functionals and basis sets. The agreements range from poor to modest depending of the choice of functionals. It is noteworthy, however, that a sulfur 3p orbital in [Co...... been isolated. The crystal structure of the resulting [Co(tacn)(C-aeaps-SCH(3))]Br(3) x 3 H(2)O at 122 K has been determined by X-ray diffraction techniques to verify the structure. The crystal structure determination shows that the carbon-cobalt bond length is even shorter (2.001(4) A) than in [Co...

  19. and cobalt(III) octahedral monomer complexes: Synthesis and ...

    Indian Academy of Sciences (India)

    In compound 2 the central cobalt is in +3 oxidation state while `in' compound 2, the nickel ion is in +2 oxidation state. The two complexes are isostructural with octahedral coordination environment exhibiting helical twist topology. They also display strong H-bonding as well as CH- interactions to generate 1D chain.

  20. Cobalt-55 positron emission tomography in ischemic stroke

    NARCIS (Netherlands)

    Jansen, HML; Paans, AMJ; Vliet, AMV; VeenmavanderDuin, L; BolwijnMeijer, CJW; Pruim, J; Willemsen, ATM; Franssen, EJF; Minderhoud, JM; Korf, J

    After acute cerebral stroke, the (peri-) infarct tissue is characterized by calcium (Ca)-mediated neuronal damage and inflammatory processes. Monitoring Ca-mediated damage using the isotope cobalt-55 (Go) as a Ga-tracer may enable PET-imaging of this tissue. Since the fate of (peri-) infarct tissue

  1. Molecular dynamics simulation of thermophysical properties of undercooled liquid cobalt

    International Nuclear Information System (INIS)

    Han, X J; Wang, J Z; Chen, M; Guo, Z Y

    2004-01-01

    Molecular dynamics simulations with two different embedded-atom-method (EAM) potentials are applied to calculate the density, specific heat and self-diffusion coefficient of liquid cobalt at temperatures above and below the melting temperature. Simulation shows that Pasianot's EAM model of cobalt constructed on the basis of a hcp structure is more successful than Stoop's EAM model in the framework of a fcc structure in predicting the thermophysical properties of liquid cobalt. Simulations with Pasianot's EAM model indicate that the density fits into ρ = 7.49-9.17 x 10 -4 (T- T m ) g cm -3 , and the self-diffusion coefficient is given by D = 1.291 x 10 -7 exp(-48 795.71/RT) m 2 s -1 . Dissimilar to the linear dependence of the density and the Arrhenius dependence of the self-diffusion coefficient on temperature, the specific heat shows almost a constant value of 38.595 ± 0.084 J mol -1 K -1 within the temperature range of simulation. The simulated properties of liquid cobalt are compared with experimental data available. Comparisons show reasonable agreements between the simulated results from Pasianot's EAM model and experimental data

  2. Pulse reversal plating of nickel-cobalt alloys

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Jaskula, M.; Kubiczek, M.

    2009-01-01

    extreme demands, in terms of tool accuracy, process temperature and tool wear, are requested. In order to meet these demands, electroforming of hard nickel alloys is an obvious way forward. This paper presents several electrolytes from which it is possible to deposit nickel-cobalt alloys with high...

  3. Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

    Indian Academy of Sciences (India)

    Cobalt oxide nanoparticle-modified carbon nanotubes as an electrocatalysts for electrocatalytic evolution of oxygen gas ... activity of CoO–MWNT/GCE increased with the number of potential cycles employed for the CoO deposition till a certain loading (20 cycles) beyond which an adverse effect is observed.

  4. Hydrothermal synthesis, characterization, and magneticproperties of cobalt chromite nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Zákutná, Dominika; Repko, A.; Matulková, I.; Nižňanský, Daniel; Ardu, A.; Cannas, C.; Mantlíková, Alice; Vejpravová, Jana

    2014-01-01

    Roč. 16, č. 2 (2014), 1-14 ISSN 1388-0764 R&D Projects: GA ČR GAP108/10/1250 Institutional support: RVO:68378271 ; RVO:61388980 Keywords : cobalt chromite * hydrothermal method * nanoparticles * size effect * multiferroic materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.184, year: 2014

  5. Hydrothermal synthesis and structure of framework cobalt phosphates

    Indian Academy of Sciences (India)

    Administrator

    Open-framework phosphates investigated in the last few years, specially those of transition metals, are of particular interest because of their potential applications in catalysis, sorption and separation techniques. Amongst the transition metals, cobalt phosphate occupies a prime position because of its interesting magnetic ...

  6. Self-supported porous Cobalt Oxide Nanowires with enhanced ...

    Indian Academy of Sciences (India)

    Development of hybrid electrocatalysts with high activity and good stability is crucial for oxygen evolution reaction (OER) of water electrocatalysis. In this work, cobalt oxide (Co₃O₄) nanowires loaded on carbon fiber paper (CFP) were synthesized via hydrothermal method and annealing. The as-synthesized ...

  7. Highly selective cobalt-catalyzed hydrovinylation of styrene

    NARCIS (Netherlands)

    Grutters, M.M.P.; van der Vlugt, J.I.; Pei, Y.; Mills, A.M.; Lutz, M.; Spek, A.L.; Müller, Christian; Moberg, C.; Vogt, D.

    2009-01-01

    Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3-phenyl-1-butene (3P1B). Double-bond isomerization, a common problem in

  8. Sorghum cobalt analysis on not determined wave length with atomic ...

    African Journals Online (AJOL)

    Jane

    2011-08-24

    Aug 24, 2011 ... 60. 70. 0. 5. 10. 15. 20. 25. Sludge treatment and its replications. A bsorbance / B ackground. Absorbance. Background. Figure 1. Absorbance and background values during Cobalt analyses of forage sorghum with atomic absorption spectrophotometer depending on measuring order (1/10,000) on 240.6 ...

  9. Cobalt-60 production in the BN-350 fast power reactor

    International Nuclear Information System (INIS)

    Zvonarev, A.V.; Korobejnikov, V.V.; Matveenko, I.P.

    1994-01-01

    A possibility of Co-60 isotope production in the BN-350 fast reactor was considered. A special irradiating device, which is an assembly with a central hole, where a container containing cobalt and zirconium hydride is placed. The irradiating device tested permits generating 60 Co with specific activity of 100 Ci/g

  10. Polymer Films with Ion-Synthesized Cobalt and Iron Nanoparticles

    DEFF Research Database (Denmark)

    Popok, Vladimir

    2014-01-01

    The current paper presents an overview and analysis of data obtained on a few sets of polymer samples implanted by iron and cobalt. The low-energy (40 keV) implantations were carried out into polyimide and polyethyleneterephthalate with fluences between 2.5x10e16-1.5x10e17 cm-2. The samples were...

  11. Effect of Trypanosoma congolense infection on serum cobalt level in ...

    African Journals Online (AJOL)

    In all groups, Cobalt (Co) was determined by the use of Atomic Absorption Spectrometer (UNICAM SOLAAR 32). The mean concentrations of Co fluctuated in the course of the experiment with slight decrease in the infected groups, but there was no significant difference (P>0.6553) with those of the control. This indicates that ...

  12. Osmium and cobalt complexes incorporating facially coordinated N ...

    Indian Academy of Sciences (India)

    Administrator

    SUPPLEMENTARY MATERIALS. Osmium and cobalt complexes incorporating facially coordinated N,N,O donor azo-imine ligands: Redox and catalytic properties. Poulami Pattanayak, a. Debprasad Patra, a. Jahar Lal Pratihar, a. Andrew Burrows,. Mary F. Mahon b and Surajit Chattopadhyay* a a. Department of Chemistry ...

  13. Osmium and cobalt complexes incorporating facially coordinated N ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 1. Osmium and cobalt complexes incorporating facially coordinated N,N,O donor azo-imine ligands: Redox and catalytic properties. Poulami Pattanayak Debprasad Patra Jahar Lal Pratihar Andrew Burrows Mary F Mahon Surajit Chattopadhyay. Volume ...

  14. Weak ferromagnetism and exchange biasing in cobalt oxide nanoparticle systems

    NARCIS (Netherlands)

    Tomou, A; Gournis, D; Panagiotopoulos, [No Value; Huang, Y; Hadjipanayis, GC; Kooi, BJ; Panagiotopoulos, I.

    2006-01-01

    Cobalt oxide nanoparticle systems have been prepared by wet chemical processing involving the encapsulation of the nanoparticles by an organic ligand shell (oleic acid and oleylamine). CoO nanoparticles were easily prepared by this method, while the synthesis of the CoPt/CoO nanocomposites was

  15. Passivation of cobalt nanocluster assembled thin films with hydrogen

    DEFF Research Database (Denmark)

    Romero, C.P.; Volodin, A.; Di Vece, M.

    2012-01-01

    The effect of hydrogen passivation on bare and Pd capped cobalt nanocluster assembled thin films was studied with Rutherford backscattering spectrometry (RBS) and magnetic force microscopy (MFM) after exposure to ambient conditions. The nanoclusters are produced in a laser vaporization cluster...

  16. Cobalt (III) complexes as novel matrix metalloproteinase-9 inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jiyoun [Sungshin Women' s Univ., Seoul (Korea, Republic of)

    2012-04-15

    We have synthesized a series of novel MMP-9 inhibitors containing cobalt(III) complexes. The synthesized cobalt(III) complexes are effective as enzyme inhibitors and the attachment of a biphenyl group enhanced the efficiency of enzyme inhibition up to 6-fold. When compared to the reported non-hydroxamate MMP inhibitors, the synthesized complexes showed comparable in vitro potency. The enzyme assay showed that the cobalt(III) complex can disrupt the zinc binding active site of MMP-9 and is proposed to work via a ligand exchange mechanism. Since histidine residues are essential for the catalytic activity of a large percentage of enzymes and zinc finger proteins, these cobalt(III) complexes can serve as a prototype inhibitor towards various zinc containing enzymes and proteins. Matrix metalloproteinases (MMPs) are a family of zinc binding endopeptidases that play crucial roles in various physiological processes and diseases such as embryogenic growth, angiogenesis, arthritis, skin ulceration, liver fibrosis and tumor metastasis. Because of their implications in a wide range of diseases, MMPs are considered as intriguing drug targets. The majority of MMP inhibitors are organic small molecules containing a hydroxamate functionality for the zinc binding group. This hydroxamate group binds to a zinc(II) center in a bidentate fashion and creates a distorted trigonal bipyramidal geometry.

  17. Comparative study on calcium, magnesium and cobalt in diabetic ...

    African Journals Online (AJOL)

    Comparative study on calcium, magnesium and cobalt in diabetic and non diabetic patients (males) in Punjab, Pakistan. A Anjum, M Yousaf, M Zuber, HB Ahmad, AF Zahoor, ZI Khan, K Ahmad, S Naheed, KG Ali, A Jabbar, TH Bukhari, S Hina, S Ahmad, MK Mukhtar, M Arshad, A Hussain ...

  18. Tailoring the magnetic properties of cobalt-ferrite nanoclusters

    Science.gov (United States)

    de la Vega, A. Estrada; Garza-Navarro, M. A.; Durán-Guerrero, J. G.; Moreno Cortez, I. E.; Lucio-Porto, R.; González-González, V.

    2016-01-01

    In this contribution, we report on the tuning of magnetic properties of cobalt-ferrite nanoclusters. The cobalt-ferrite nanoclusters were synthesized from a two-step approach that consists of the synthesis of cobalt-ferrite nanoparticles in organic media, followed by their dispersion into aqueous dissolution to form an oil-in-water emulsion. These emulsions were prepared at three different concentrations of the cationic surfactant cetyltrimethylammonium bromide (CTAB), in order to control the size and clustering density of the nanoparticles in the nanoclusters. The synthesized samples were characterized by transmission electron microscopy and their related techniques, such as bright-field and Z-contrast imaging, electron diffraction and energy-dispersive X-ray spectrometry; as well as static magnetic measures. The experimental evidence indicates that the size, morphology, and nanoparticles clustering density in the nanoclusters is highly dependent of the cobalt-ferrite:CTAB molar ratio that is used in their synthesis. In addition, due to the clustering of the nanoparticles into the nanoclusters, their magnetic moments are blocked to relax cooperatively. Hence, the magnetic response of the nanoclusters can be tailored by controlling the size and nanoparticles clustering density.

  19. IN SITU AND POST REACTION COBALT-INCORPORATION INTO ...

    African Journals Online (AJOL)

    a

    3-aminopropyltriethoxysilane, Sol-gel, Cobalt. INTRODUCTION. The sol-gel method is widely used to synthesise periodic mesoporous organosilica (PMOs) materials containing both bridging organic functional moieties in the framework and terminal organic functional groups protruding into the channel pores [1 – 20].

  20. Tailoring the magnetic properties of cobalt-ferrite nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Vega, A. Estrada de la; Garza-Navarro, M. A., E-mail: marco.garzanr@uanl.edu.mx; Durán-Guerrero, J. G.; Moreno Cortez, I. E.; Lucio-Porto, R.; González-González, V. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica (Mexico)

    2016-01-15

    In this contribution, we report on the tuning of magnetic properties of cobalt-ferrite nanoclusters. The cobalt-ferrite nanoclusters were synthesized from a two-step approach that consists of the synthesis of cobalt-ferrite nanoparticles in organic media, followed by their dispersion into aqueous dissolution to form an oil-in-water emulsion. These emulsions were prepared at three different concentrations of the cationic surfactant cetyltrimethylammonium bromide (CTAB), in order to control the size and clustering density of the nanoparticles in the nanoclusters. The synthesized samples were characterized by transmission electron microscopy and their related techniques, such as bright-field and Z-contrast imaging, electron diffraction and energy-dispersive X-ray spectrometry; as well as static magnetic measures. The experimental evidence indicates that the size, morphology, and nanoparticles clustering density in the nanoclusters is highly dependent of the cobalt-ferrite:CTAB molar ratio that is used in their synthesis. In addition, due to the clustering of the nanoparticles into the nanoclusters, their magnetic moments are blocked to relax cooperatively. Hence, the magnetic response of the nanoclusters can be tailored by controlling the size and nanoparticles clustering density.

  1. Synthesis and characterization of cobalt-manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Valencia, J. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis 55455-0153 (United States); Arias, N.P. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Departamento de Ingenieria Electrica, Electronica y Computacion, Facultad de Ingenieria y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Giraldo, O. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Rosales-Rivera, A., E-mail: arosalesr@unal.edu.co [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia)

    2012-08-15

    Cobalt doped/un-doped manganese oxides materials were synthesized at various doping rates by soft chemical reactions, oxidation-reduction method, which allows generating a metal-mixed oxide. The synthesized materials were characterized using several techniques including chemical analysis, X-rays diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The chemical analysis confirmed the presence of cobalt in the samples. XRD patterns reveal mainly a spinel-like structure and SEM micrographs exhibited morphology with fine aggregate of particles. TGA profiles showed weight loss due to loss of water in a first step, followed by a loss of oxygen from the lattice associated with partial reduction of Mn{sup 4+} to Mn{sup 3+}. VSM was used to measure the magnetization as a function of the applied magnetic field at temperatures T=50 and 300 K. Different magnetic behaviors were observed when cobalt percentage changed in the samples. These behaviors are considered to be related to the size of the particles and composition of the materials. Higher coercive field and lesser magnetization were observed for the sample with higher cobalt content.

  2. Cobalt(II) supported on ethylenediamine-functionalized ...

    Indian Academy of Sciences (India)

    Vol. 126, No. 1, January 2014, pp. 111–115. c Indian Academy of Sciences. Cobalt(II) supported on ethylenediamine-functionalized nanocellulose as an efficient catalyst for room temperature aerobic oxidation of alcohols. AHMAD SHAABANI. ∗. , SAJJAD KESHIPOUR, MONA HAMIDZAD and MOZHDEH SEYYEDHAMZEH.

  3. Synthesis and characterization of gel-grown cobalt tartrate crystals

    Indian Academy of Sciences (India)

    rate, or for heating to acquire a constant mass loss with time. The TGA curve for cobalt tartrate crystals is shown in figure 5. There are four stages of decomposition starting from room temperature of 40. ◦. C. The first stage of decompo- sition starts from 40. ◦. C and continues up to 200. ◦. C where the weight loss is about 25%.

  4. Synthesis and Characterization of a Schiff Base Cobalt (III) Complex ...

    African Journals Online (AJOL)

    2017-12-18

    Dec 18, 2017 ... Synthesis and Characterization of a Schiff Base Cobalt (III) Complex and ... zinc, palladium, magnesium and gold and most ..... Synthesis, spectral characterization, solution equilibria, in vitro antibacterial and cytotoxic activities of Cu(II), Ni(II), Mn(II), Co(II) and Zn(II) complexes with Schiff base derived from 5 ...

  5. Preparation and characterization of zinc and cobalt (II, III) oxides ...

    Indian Academy of Sciences (India)

    n junction, which can decrease the band gap energy and thus increase the photocatalytic activity. This work reports the preparation and charac- terization of cobalt oxide and oxide mixtures of Zn and Co in 1, 3 and 5% proportions, respectively, ...

  6. synthesis, characterisation and antimicrobial activities of cobalt(ii)

    African Journals Online (AJOL)

    Preferred Customer

    *Corresponding author. E-mail: agwara29@yahoo.com; Tel. 237 798 75425. SYNTHESIS, CHARACTERISATION AND ANTIMICROBIAL ACTIVITIES OF. COBALT(II), COPPER(II) AND ZINC(II) MIXED-LIGAND COMPLEXES. CONTAINING 1,10-PHENANTHROLINE AND 2,2'-BIPYRIDINE. M.O. Agwara1*, P.T. Ndifon1, N.B. ...

  7. Sorghum cobalt analysis on not determined wave length with atomic ...

    African Journals Online (AJOL)

    This study was to know the better wave length on measuring cobalt content in forage sorghum hybrid (Sorghum bicolor) with an atomic absorption spectrophotometer. The analysis was on background correction mode with three wave lengths; 240.8, 240.7 (determined wave length or recommended wave length) and 240.6 ...

  8. Synthesis and characterization of cobalt-manganese oxides

    International Nuclear Information System (INIS)

    Valencia, J.; Arias, N.P.; Giraldo, O.; Rosales-Rivera, A.

    2012-01-01

    Cobalt doped/un-doped manganese oxides materials were synthesized at various doping rates by soft chemical reactions, oxidation-reduction method, which allows generating a metal-mixed oxide. The synthesized materials were characterized using several techniques including chemical analysis, X-rays diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The chemical analysis confirmed the presence of cobalt in the samples. XRD patterns reveal mainly a spinel-like structure and SEM micrographs exhibited morphology with fine aggregate of particles. TGA profiles showed weight loss due to loss of water in a first step, followed by a loss of oxygen from the lattice associated with partial reduction of Mn 4+ to Mn 3+ . VSM was used to measure the magnetization as a function of the applied magnetic field at temperatures T=50 and 300 K. Different magnetic behaviors were observed when cobalt percentage changed in the samples. These behaviors are considered to be related to the size of the particles and composition of the materials. Higher coercive field and lesser magnetization were observed for the sample with higher cobalt content.

  9. Cobalt Doped SnO2 Thick Film Gas Sensors: Conductance and Gas Response Characteristics for LPG and CNG Gas

    OpenAIRE

    V. Kumar; S. K. Srivastava; Kiran Jain

    2009-01-01

    Cobalt doped thick films tin oxide sensors were studied for their LPG and CNG gas sensitivity. SnO2 powder was synthesized by precipitation technique and doped with cobalt sulphate (0 to 10 wt %) by impregnation technique. The sensing characteristics were found to depend on the cobalt concentration and operating temperature. Best performance for LPG and CNG detection was obtained for 3 wt % addition of cobalt sulphate. Cobalt doped SnO2 sensors showed a decrease in the optimum temperature for...

  10. Human metabolism of orally administered radioactive cobalt chloride.

    Science.gov (United States)

    Holstein, H; Ranebo, Y; Rääf, C L

    2015-05-01

    This study investigated the human gastrointestinal uptake (f1) and subsequent whole-body retention of orally administered inorganic radioactive cobalt. Of eight adult volunteers aged between 24 and 68 years, seven were given solutions of (57)Co (T1/2 = 272 d) containing a stable cobalt carrier, and six were given carrier-free (58)Co (T1/2 = 71 d). The administered activities ranged between 25 and 103 kBq. The observed mean f1, based on 6 days accumulated urinary excretion sampling and whole-body counting, was 0.028 ± 0.0048 for carrier-free (58)Co, and 0.016 ± 0.0021 for carrier-associated (57)Co. These values were in reasonable agreement with values reported from previous studies involving a single intake of inorganic cobalt. The time pattern of the total retention (including residual cobalt in the GI tract) included a short-term component with a biological half-time of 0.71 ± 0.03 d (average ± 1 standard error of the mean for the two nuclides), an intermediate component with a mean half-time of 32 ± 8.5 d, and a long-term component (observed in two volunteers) with half-times ranging from 80 to 720 d for the two isotopes. From the present data we conclude that for the short-lived (57)Co and (58)Co, more than 95% of the internal absorbed dose was delivered within 7 days following oral intake, with a high individual variation influenced by the transit time of the unabsorbed cobalt through the gastro-intestinal tract. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Cobalt Porphyrin-Polypyridyl Surface Coatings for Photoelectrosynthetic Hydrogen Production.

    Science.gov (United States)

    Beiler, A M; Khusnutdinova, D; Wadsworth, B L; Moore, G F

    2017-10-16

    Hybrid materials that link light capture and conversion technologies with the ability to drive reductive chemical transformations are attractive as components in photoelectrosynthetic cells. We show that thin-film polypyridine surface coatings provide a molecular interface to assemble cobalt porphyrin catalysts for hydrogen evolution onto a visible-light-absorbing p-type gallium phosphide semiconductor. Spectroscopic techniques, including grazing angle attenuated total reflection Fourier transform infrared spectroscopy, confirm that the cobalt centers of the porphyrin macrocycles coordinate to pyridyl nitrogen sites of the organic surface coating. The cobalt porphyrin surface concentration and fraction of pyridyl sites coordinated to a cobalt center are quantified using complementary methods of ellipsometry, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. In aqueous solutions under simulated solar illumination the modified cathode is photochemically active for hydrogen production, generating the product gas with near-unity Faradaic efficiency at a rate of ≈10 μL min -1 cm -2 when studied in a three-electrode configuration and polarized at the equilibrium potential of the H + /H 2 couple. This equates to a photoelectrochemical hydrogen evolution reaction activity of 17.6 H 2 molecules s -1 Co -1 , the highest value reported to date for a molecular-modified semiconductor. Key features of the functionalized photocathode include (1) the relative ease of synthetic preparation made possible by application of an organic surface coating that provides molecular recognition sites for immobilizing the cobalt porphyrin complexes at the semiconductor surface and (2) the use of visible light to drive cathodic fuel-forming reactions in aqueous solutions with no added organic acids or sacrificial chemical reductants.

  12. An analysis of cobalt irradiation in CANDU 6 reactor core

    International Nuclear Information System (INIS)

    Gugiu, E.D.; Dumitrache, I.

    2003-01-01

    In CANDU reactors, one has the ability to replace the stainless steel adjuster rods with neutronically equivalent Co assemblies with a minimum impact on the power plant safety and efficiency. The 60 Co produced by 59 Co irradiation is used extensively in medicine and industry. The paper mainly describes some of the reactor physics and safety requirements that must be carried into practice for the Co adjuster rods. The computations related to the neutronically equivalence of the stainless steel adjusters with the Co adjuster assemblies, as well as the estimations of the activity and the heating of the irradiated cobalt rods are performed using the Monte Carlo codes MCNP5 and MONTEBURNS2.1. The 60 Co activity and heating evaluations are closely related to the neutronics computations and to the density evolution of cobalt isotopes during assumed in-core irradiation period. Unfortunately, the activities of these isotopes could not be evaluated directly using the burn-up capabilities of the MONTEBURNS code because of the lack of their neutron cross-section from the MCNP5 code library. Additional MCNP5 runs for all the cobalt assemblies have been done in order to compute the flux-spectrum, the 59 Co and the 60 Co radiative capture reaction rates in the adjusters. The 60m Co cross-section was estimated using the flux-spectrum and the ORIGEN2.1 code capabilities THERM and RES. These computational steps allowed the evaluation of the one-group cross-section for the radiative capture reactions of cobalt isotopes. The values obtained replaced the corresponding ones from the ORIGEN library, which have been estimated using the flux-spectrum specific to the fuel. The activity values are used to evaluate the dose at the surface of the device designed to transport the cobalt adjusters. (authors)

  13. Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application

    Energy Technology Data Exchange (ETDEWEB)

    Kulanthaivel, Senthilguru [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India); Roy, Bibhas [Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Agarwal, Tarun [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India); Giri, Supratim [Department of Chemistry, National Institute of Technology, Rourkela, Odisha 769008 (India); Pramanik, Krishna; Pal, Kunal; Ray, Sirsendu S. [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India); Maiti, Tapas K. [Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Banerjee, Indranil, E-mail: indraniliit@gmail.com [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India)

    2016-01-01

    ABSTRACT: The present study delineates the synthesis and characterization of cobalt doped proangiogenic–osteogenic hydroxyapatite. Hydroxyapatite samples, doped with varying concentrations of bivalent cobalt (Co{sup 2+}) were prepared by the ammoniacal precipitation method and the extent of doping was measured by ICP–OES. The crystalline structure of the doped hydroxyapatite samples was confirmed by XRD and FTIR studies. Analysis pertaining to the effect of doped hydroxyapatite on cell cycle progression and proliferation of MG-63 cells revealed that the doping of cobalt supported the cell viability and proliferation up to a threshold limit. Furthermore, such level of doping also induced differentiation of the bone cells, which was evident from the higher expression of differentiation markers (Runx2 and Osterix) and better nodule formation (SEM study). Western blot analysis in conjugation with ELISA study confirmed that the doped HAp samples significantly increased the expression of HIF-1α and VEGF in MG-63 cells. The analysis described here confirms the proangiogenic–osteogenic properties of the cobalt doped hydroxyapatite and indicates its potential application in bone tissue engineering. - Highlights: • Cobalt (Co{sup +2}) doped hydroxyapatite (Co-HAp) can be prepared by the wet chemical method. • The concentration of Co{sup +2} influences the physico-chemical properties of HAp. • Co-HAp was found to be biocompatible and osteogenic. • Co-HAp enhanced cellular VEGF secretion through HIF-1α stabilization. • The optimum biological performance of Co-HAp was achieved for 0.33% (w/w) Co{sup +2} doping.

  14. Catalyseurs sulfures à base de cobalt et d'hydroxyapatite

    Science.gov (United States)

    El Ouassouli, A.; Ezzemouri, S.; Ezzamarty, A.; Lakhdar, M.; Leglise, J.

    1999-07-01

    We have prepared a series of catalysts combining cobalt and a hydroxyapatite by coprecipitation in a basic medium. These sulfided solids catalyse the hydrodesulfurization of dimethyldisulfide at 360 circC and its hydrogenolyzis into CH3SH at 200 circC. The coprecipitated solids are found more active than the impregnated catalysts because they exhibit a better dispersion of the active Co-S phase at higher Co content. With the precipitated catalysts, Co ions substitute for Ca ions into the apatite structure. The formation of large sulfide particles is thus more difficult as a result of sulfiding because the Co ions have to move to the surface. The apatite catalysts are intrinsically as active as their homologous Co/Al2O3. Nous avons préparé par coprécipitation en milieu basique des solides associant du cobalt à une hydroxyapatite déficitaire en calcium. Le cobalt se substitue en partie au calcium dans le réseau de l'apatite. La dispersion du cobalt est meilleure que dans des solides préparés par imprégnation. Les catalyseurs sulfurés sont capables de désulfurer complètement le diméthyldisulfure à 360 circC et de l'hydrogénolyser en CH3SH à 200 circC. Le cobalt est extrait à la surface lors de la sulfuration limitant l'agglomération en grosses particules de sulfure peu actif. Les catalyseurs coprécipités sont plus actifs que les catalyseurs imprégnés. L'activité intrinsèque des catalyseurs apatitiques est identique à celle des catalyseurs supportés sur alumine.

  15. Cobalt toxicity: Chemical and radiological combined effects on HaCaT keratinocyte cell line

    Energy Technology Data Exchange (ETDEWEB)

    Gault, N. [CEA Fontenay aux Roses, DSV/IRCM/SCSR/LRTS, 92265 Fontenay aux Rose (France); Sandre, C.; Moulin, B.; Bresson, C. [CEA, DEN, SECR, Laboratoire de Speciation des Radionucleides et des Molecules, F-91191 Gif-sur-Yvette (France); Poncy, J.L. [CEA Bruyeres Le Chatel, DSV/IRCM/SREIT/LRT, 91680 Bruyeres Le Chatel (France); Lefaix, J.L. [CEA Caen, DSV/IRCM/SRO/LARIA, 14070 Caen (France)

    2010-07-01

    Cobalt (Co) is an essential trace element well known as a constituent of vitamin B12, but different compounds of Co are also described as highly toxic and/or radio-toxic for individuals or the environment. In nuclear power plants, {sup 58}Co and {sup 60}Co are radioactive isotopes of cobalt present as activation products of stable Co and Ni used in alloys. Skin exposure is a current occupational risk in the hard metal and nuclear industries. As biochemical and molecular cobalt-induced toxicological mechanisms are not fully identified, we investigated cobalt toxicity in a model human keratinocyte cell line, HaCaT. In this study, we propose a model to determine the in vitro chemical impact on cell viability of a soluble form of cobalt (CoCl{sub 2}) with or without {gamma}-ray doses to mimic contamination by {sup 60}Co, to elucidate the mechanisms of cobalt intracellular chemical and radiological toxicity. Intracellular cobalt concentration was determined after HaCaT cell contamination and chemical toxicity was evaluated in terms of cellular viability and clonogenic survival. We investigated damage to DNA in HaCaT cells by combined treatment with chemical cobalt and a moderate {gamma}-ray dose. Additive effects of cobalt and irradiation were demonstrated. The underlying mechanism of cobalt toxicity is not clearly established, but our results seem to indicate that the toxicity of Co(II) and of irradiation arises from production of reactive oxygen species. (authors)

  16. Cobalt toxicity: Chemical and radiological combined effects on HaCaT keratinocyte cell line

    International Nuclear Information System (INIS)

    Sandre, C.; Moulin, C.; Bresson, C.; Gault, N.; Poncy, J. L.; Lefaix, J. L.

    2010-01-01

    Cobalt (Co) is an essential trace element well known as a constituent of vitamin B 12 , but different compounds of Co are also described as highly toxic and/or radio-toxic for individuals or the environment. In nuclear power plants, 58 Co and 60 Co are radioactive isotopes of cobalt present as activation products of stable Co and Ni used in alloys. Skin exposure is a current occupational risk in the hard metal and nuclear industries. As biochemical and molecular cobalt-induced toxicological mechanisms are not fully identified, we investigated cobalt toxicity in a model human keratinocyte cell line, HaCaT. In this study, we propose a model to determine the in vitro chemical impact on cell viability of a soluble form of cobalt (CoCl 2 ) with or without gamma-ray doses to mimic contamination by 60 Co, to elucidate the mechanisms of cobalt intracellular chemical and radiological toxicity. Intracellular cobalt concentration was determined after HaCaT cell contamination and chemical toxicity was evaluated in terms of cellular viability and clonogenic survival. We investigated damage to DNA in HaCaT cells by combined treatment with chemical cobalt and a moderate gamma-ray dose. Additive effects of cobalt and irradiation were demonstrated. The underlying mechanism of cobalt toxicity is not clearly established, but our results seem to indicate that the toxicity of Co(II) and of irradiation arises from production of reactive oxygen species. (authors)

  17. Alleviating effects of calcium on cobalt toxicity in two barley genotypes differing in cobalt tolerance.

    Science.gov (United States)

    Lwalaba, Jonas Lwalaba Wa; Zvobgo, Gerald; Fu, Liangbo; Zhang, Xuelei; Mwamba, Theodore Mulembo; Muhammad, Noor; Mundende, Robert Prince Mukobo; Zhang, Guoping

    2017-05-01

    Cobalt (Co) contamination in soils is becoming a severe issue in environment safety and crop production. Calcium (Ca) , as a macro-nutrient element, shows the antagonism with many divalent heavy metals and the capacity of alleviating oxidative stress in plants. In this study, the protective role of Ca in alleviating Co stress was hydroponically investigated using two barley genotypes differing in Co toxicity tolerance. Barley seedlings exposed to 100µM Co showed the significant reduction in growth and photosynthetic rate, and the dramatic increase in the contents of reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH) and oxidized glutathione (GSSG), and the activities of anti-oxidative enzymes, with Ea52 (Co-sensitive) being much more affected than Yan66 (Co-tolerant). Addition of Ca in growth medium alleviated Co toxicity by reducing Co uptake and enhancing the antioxidant capacity. The effect of Ca in alleviating Co toxicity was much greater in Yan66 than in Ea52. The results indicate that the alleviation of Co toxicity in barley plants by Ca is attributed to the reduced Co uptake and enhanced antioxidant capacity. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. bis (trimethylenediamine)cobalt(iii) mediated

    African Journals Online (AJOL)

    10. Morrow, J.R.; Trogler, W.C. Inorg. Chem. 1989, 28, 2330. 11. Zewdu, A. M.Sc. Thesis, Addis Ababa University: Addis Ababa (Ethiopia); 1990. 12. Milbum, R.M.; Gautam-Basak, M.; Tribolet, R.; Siegel, H. J. Amer. Chem. Soc. 1985, 107,. 3315. 13. Kenley, R.A.; Fleming, R.A.; Laine, R.M.; Tse, D.S.; Winter, J.S. Inorg. Chem.

  19. Development of a universal solvent for the decontamination of acidic liquid radioactive wastes

    International Nuclear Information System (INIS)

    Todd, T.A.; Brewer, K.N.; Law, J.D.; Wood, D.J.; Herbst, R.S.; Romanovskij, V.N.; Esimantovskij, V.M.; Smirnov, I.V.; Babain, V.A.

    1998-01-01

    The cobalt dicarbollide solvent extraction process has been demonstrated to be effective at removing cesium and strontium from acidic waste solutions. A collaborative development program has resulted in the development of alternative non-nitroaromatic solvents typically used in the cobalt dicarbollide process. Using the non-aromatic solvents, decontamination of acidic waste has been demonstrated using chlorinated cobalt dicarbollide with and without polyethylene glycol added. Polyethylene glycol facilitates the extraction of strontium in the cobalt dicarbollide process. A universal solvent has been developed which includes a phosphine oxide derivative added chlorinated cobalt dicarbollide/PEG solvent to facilitate simultaneous extraction of actinides, rare earth elements, technetium, strontium and cesium. This solvent was tested in a series of batch laboratory contacts in a shielded hot cell facility using actual highly radioactive tank waste. Two solvents were tested, one less dense than the aqueous waste and the other more dense. Decontamination factors of > 95% for Cs, 99.7% for Sr, and 99.99% for alpha-emitting radionuclides were achieved in four successive batch contacts. The universal solvent was also tested in a countercurrent process with simulated waste using 26 stages of 3.3-cm centrifugal contactors. The process tested utilized the light solvent and europium was used to simulate rare earths and americium in the waste simulant. Results of the countercurrent flowsheet test will be presented. If successfully demonstrated, the universal solvent could offer many advantages to individual processes to remove radionuclides from the acidic waste at the INEEL

  20. Cobalt bioavailability from hard metal particles. Further evidence that cobalt alone is not responsible for the toxicity of hard metal particles.

    Science.gov (United States)

    Lison, D; Lauwerys, R

    1994-01-01

    Hard metal is an alloy of tungsten carbide (WC) in a matrix of cobalt metal (Co). The inhalation of hard metal dust can cause an alveolitis which may progress to interstitial fibrosis. This study was undertaken to compare, both in vivo and in vitro, the bioavailability of cobalt metal when mixed or not with WC and to assess whether this factor had any influence on the cellular toxicity of hard metal particles. In vivo, non-toxic doses of cobalt metal were administered intratracheally in the rat, alone (Co, 0.03 mg/100 g) or mixed with tungsten carbide (WC-Co, 0.5 mg/100 g containing 6.3% of cobalt metal particles). Sequential measurements of cobalt in the lung and in urine demonstrated that the retention time of the metal in the lung was longer in Co- than in WC-Co-treated animals. In vitro, the cellular cobalt uptake was higher when the metal was presented to the macrophages as WC-Co. However, there was no relationship between the cellular uptake of cobalt and the occurrence of toxicity, since the intracellular concentration of cobalt associated with the occurrence of a cytotoxic effect of WC-Co particles was insufficient to exert the same effect when resulting from exposure to Co alone. This clearly indicates that increased bioavailability of cobalt is not the mechanism by which hard metal particles exhibit their cellular toxicity. These observations confirm and extend our previous findings supporting the view that cobalt is not the only component responsible for the toxicity of hard metal particles which should be considered as a specific toxic entity.

  1. World production and possible recovery of cobalt from the Kupferschiefer stratiform copper ore

    Directory of Open Access Journals (Sweden)

    Pazik Paulina M.

    2016-01-01

    Full Text Available Cobalt is recognized as a strategic metal and also E-tech element, which is crucial for worlds development. An increasing demand for cobalt forces for searching of new resources that could be explored in European countries. There are many examples of cobalt recoveries, mostly from laterite and sulphide deposits. However, the accurate choice of the technology depends on many factors. The Kupferschiefer stratiform copper ore located in Poland is the biggest deposit of cobalt in Europe. Although KGHM Polska Miedz S.A. recovers many precious metals from this ore, cobalt is not recovered yet. This metal occurs as an accompanying element, mostly in the form of cobaltite (CaAsS, with the average content of 50–80 g/Mg. In this paper a possible recovery of cobalt from the Kupferschiefer ore, with the use of hydrometallurgical methods, was investigated.

  2. Copper catalysis for enhancement of cobalt leaching and acid utilization efficiency in microbial fuel cells.

    Science.gov (United States)

    Liu, Yaxuan; Shen, Jingya; Huang, Liping; Wu, Dan

    2013-11-15

    Enhancement of both cobalt leaching from LiCoO2 and acid utilization efficiency (AUE) in microbial fuel cells (MFCs) was successfully achieved by the addition of Cu(II). A dosage of 10mg/L Cu(II) improved both cobalt leaching up to 308% and AUE of 171% compared to the controls with no presence of Cu(II). The apparent activation energy of cobalt leaching catalyzed by Cu(II) in MFCs was only 11.8 kJ/mol. These results demonstrate cobalt leaching in MFCs using Cu(II) as a catalyst may be an effective strategy for cobalt recovery and recycle of spent Li-ion batteries, and the evidence of influence factors including solid/liquid ratio, temperature, and pH and solution conductivity can contribute to improving understanding of and optimizing cobalt leaching catalyzed by Cu(II) in MFCs. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Estimation of cobalt release from feed water heater tubes of BWRs

    International Nuclear Information System (INIS)

    Uchida, S.; Kitamura, M.; Ozawa, Y.

    1983-01-01

    To evaluate the release source of cobalt from heater tubes of the feed water line, release rate measurements were carried out by detecting 60 Co released from irradiated stainless steel in contact with neutral water at an oxygen concentration of 20 ppb. The dependences of cobalt release rate on temperature, flow velocity and exposure time were studied after 670 hours of release experiments, and an empirical equation (which is presented) was obtained in the temperature range from 150 to 240 deg C. A decrease in the cobalt release rate above 250 deg C was considered due to the formation of a protective oxide layer. From these data, the amount of cobalt released from individual feed water heaters was evaluated. It was demonstrated that low cobalt containing stainless steel was economically applied only in the higher temperature region of the heater (20% of the total surface) to reduce cobalt feed rate into the reactor (to approx. 1/2). (author)

  4. Effects of cobalt on structure, microchemistry and properties of a wrought nickel-base superalloy

    Science.gov (United States)

    Jarrett, R. N.; Tien, J. K.

    1982-01-01

    The effect of cobalt on the basic mechanical properties and microstructure of wrought nickel-base superalloys has been investigated experimentally by systematically replacing cobalt by nickel in Udimet 700 (17 wt% Co) commonly used in gas turbine (jet engine) applications. It is shown that the room temperature tensile yield strength and tensile strength only slightly decrease in fine-grained (disk) alloys and are basically unaffected in coarse-grained (blading) alloys as cobalt is removed. Creep and stress rupture resistances at 760 C are found to be unaffected by cobalt level in the blading alloys and decrease sharply only when the cobalt level is reduced below 8 vol% in the disk alloys. The effect of cobalt is explained in terms of gamma prime strengthening kinetics.

  5. Modulation of synthetic parameters of cobalt nanoparticles: TEM, EDS, spectral and thermal studies

    Science.gov (United States)

    Chandra, Sulekh; Kumar, Avdhesh

    2012-12-01

    The study focuses on the modulation of synthetic parameters in order to influence the size, structure, composition and arrangement of nanoparticles of cobalt. Cobalt nanoparticles were synthesized by ethanolic solution of benzildiethylenetriamine in cobalt nitrate solution at 60 °C with stirring and refluxing leads to nanoparticles of cobalt. The morphology and structure of the synthesized nanoparticles of cobalt were characterized by Transmission Electron Microscopy (TEM), Powder X-ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), QELS Data and Infrared Spectroscopy (IR). Crystalline size was 20 nm determined from the sharp peak at 2θ = 25 °C from the powder XRD. TEM images of cobalt nanoparticles without reducing agent having the diameter 20 nm with spherical shape and black color.

  6. Antifungal activity of nicotine and its cobalt complex

    International Nuclear Information System (INIS)

    Zaidi, M.I.; Gul, A.

    2005-01-01

    Nicotine and its metal complex; Co(II)-nicotine were isolated from leaves of Nicotiana tabacum using various metal ions by the reported techniques and studied for their antifungal activity against fourteen different species of fungi. For comparative study, pure sample of nicotine and metal salt used for complexation; cobalt(II) chloride was also subjected to antifungal tests with the same species of fungus under similar conditions. Results indicated that nicotine had antifungal activity against all species of fungi studied except Candida albicans, Microsporum canis, Epidermophyton floccosum, Candida tropicalis, and Alternaria infectoria. Cobalt(II) nicotine was found to be effective against all selected species of fungi but ineffective against Candida solani, Penicillium notalum, Microsporum canis, Fusarium solani and Fusarium moniliforme. (author)

  7. Iron, lead, and cobalt absorption: similarities and dissimilarities

    International Nuclear Information System (INIS)

    Barton, J.C.; Conrad, M.E.; Holland, R.

    1981-01-01

    Using isolated intestinal segments in rats, the absorption of iron, lead, and cobalt was increased in iron deficiency and decreased in iron loading. Similarly, the absorption of these metals was decreased in transfusional erythocytosis, after intravenous iron injection and after parenteral endotoxin injection. Acute bleeding or abbreviated intervals of dietary iron deprivation resulted in increased iron absorption from isolated intestinal segments and in intact animals, while the absorption of lead and cobalt was unaffected. These results suggest that the specificity of the mucosal metal absorptive mechanism is either selectively enhanced for iron absorption by phlebotomy or brief periods of dietary iron deprivation, or that two or more mucosal pathways for iron absorption may exist

  8. Manipulation of morphology and magnetic properties in cobalt nanowires

    Directory of Open Access Journals (Sweden)

    Chenglin Li

    2017-05-01

    Full Text Available Ferromagnetic metallic Cobalt nanowires are synthesized by the reduction of carboxylate salts of Co in 1, 2-butanediol using a solvothermal chemical process. In this process, the size and shape of the nanocrystals can be controlled via reaction parameters such as surfactant ratio, precursor concentration, and the temperature ramp. Synthesized Co nanocrystals exhibit the hexagonally close-packed phase favored the growth of anisotropic particles and the (002 crystalline direction is along the long axis of the nanowires. By varying the catalyst concentration in proper range, the effect of synthetic parameters on controlling Co nanoparticles with different length of 50 - 700 nm was systematically studied. Magnetic measurements and TEM images of the Cobalt nanowires indicate that the coercivity of the Co nanowires depends substantially on the morphology. The obtained highest coercivity of 8.4 kOe can be attributed to their small mean diameter and high crystallinity of nanowires for 200 - 300 nm.

  9. Removal of radioactive cobalt from highly saline streams

    International Nuclear Information System (INIS)

    Hunkele, W.; Barkatt, A.; Macedo, P.B.; Sutter, H.

    1984-01-01

    The removal of radioactive cobalt by ion-exchange from saline waters such as streams which contain high levels of brackish water or seawater is complicated by the complex chemical spectrum of cobalt in such streams and by the high concentrations of other ions such as sodium. Side by side comparisons of strong acid organic ion-exchangers typically used in nuclear power plant waste water clean-up and a novel new ion-exchanger, Durasil 70 have been carried out in the laboratory using synthetic waste streams an in an operating nuclear power plant (Salen Generating Station) using actual plant waste water. The results show the Durasil 70 to have a capacity at least 15 time greater than the organic resin. Durasil 70 also gives improved decontamination factors (DF) and allows for faster process times

  10. Radiation regression patterns after cobalt plaque insertion for retinoblastoma

    International Nuclear Information System (INIS)

    Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

    1983-01-01

    An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy)

  11. Radiation regression patterns after cobalt plaque insertion for retinoblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

    1983-08-01

    An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy).

  12. Ultrasonography-guided cobalt-60 brachytherapy for malignant glioma

    International Nuclear Information System (INIS)

    Sakai, Noboru; Takenaka, Katsunobu; Ueda, Tatsuya

    1989-01-01

    Brachytherapy with cobalt-60 source is reported. In this method it is characterized that the source is inserted interstitially with remote control system by after-loading method via outer catheter (using tandem tube), which was established in the center of residual tumor, using ultrasonography guide with trepanation, or intraoperatively put within the dead space after tumor resection. Six cases of deep-seated and recurrent malignant glioma, were treated with this method. A total dose of 20 to 45 Gy (10 to 15 Gy/day for 2 to 3 days) was delivered to the target. Additionally conventional external irradiation was followed. The effect of cobalt-60 brachytherapy on such tumors were favorable especially for well-circumscribed glioma less than 3 cm on CT scan. (author)

  13. Radiation dose distributions due to sudden ejection of cobalt device.

    Science.gov (United States)

    Abdelhady, Amr

    2016-09-01

    The evaluation of the radiation dose during accident in a nuclear reactor is of great concern from the viewpoint of safety. One of important accident must be analyzed and may be occurred in open pool type reactor is the rejection of cobalt device. The study is evaluating the dose rate levels resulting from upset withdrawal of co device especially the radiation dose received by the operator in the control room. Study of indirect radiation exposure to the environment due to skyshine effect is also taken into consideration in order to evaluate the radiation dose levels around the reactor during the ejection trip. Microshield, SHLDUTIL, and MCSky codes were used in this study to calculate the radiation dose profiles during cobalt device ejection trip inside and outside the reactor building. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Pairwise cobalt doping of boron carbides with cobaltocene

    Science.gov (United States)

    Ignatov, A. Yu.; Losovyj, Ya. B.; Carlson, L.; LaGraffe, D.; Brand, J. I.; Dowben, P. A.

    2007-10-01

    We have performed Co K-edge x-ray absorption fine structure and x-ray absorption near edge structure measurements of Co-doped plasma enhanced chemical vapor phase deposition (PECVD) grown "C2B10Hx" semiconducting boron carbides, using cobaltocene. Cobalt does not dope PECVD grown boron carbides as a random fragment of the cobaltocene source gas. The Co atoms are fivefold boron coordinated (R=2.10±0.02Å) and are chemically bonded to the icosahedral cages of B10CHx or B9C2Hy. Pairwise Co doping occurs, with the cobalt atoms favoring sites some 5.28±0.02Å apart.

  15. Coastal sources, sinks and strong organic complexation of dissolved cobalt within the US North Atlantic GEOTRACES transect GA03

    Science.gov (United States)

    Noble, Abigail E.; Ohnemus, Daniel C.; Hawco, Nicholas J.; Lam, Phoebe J.; Saito, Mak A.

    2017-06-01

    Cobalt is the scarcest of metallic micronutrients and displays a complex biogeochemical cycle. This study examines the distribution, chemical speciation, and biogeochemistry of dissolved cobalt during the US North Atlantic GEOTRACES transect expeditions (GA03/3_e), which took place in the fall of 2010 and 2011. Two major subsurface sources of cobalt to the North Atlantic were identified. The more prominent of the two was a large plume of cobalt emanating from the African coast off the eastern tropical North Atlantic coincident with the oxygen minimum zone (OMZ) likely due to reductive dissolution, biouptake and remineralization, and aeolian dust deposition. The occurrence of this plume in an OMZ with oxygen above suboxic levels implies a high threshold for persistence of dissolved cobalt plumes. The other major subsurface source came from Upper Labrador Seawater, which may carry high cobalt concentrations due to the interaction of this water mass with resuspended sediment at the western margin or from transport further upstream. Minor sources of cobalt came from dust, coastal surface waters and hydrothermal systems along the Mid-Atlantic Ridge. The full depth section of cobalt chemical speciation revealed near-complete complexation in surface waters, even within regions of high dust deposition. However, labile cobalt observed below the euphotic zone demonstrated that strong cobalt-binding ligands were not present in excess of the total cobalt concentration there, implying that mesopelagic labile cobalt was sourced from the remineralization of sinking organic matter. In the upper water column, correlations were observed between total cobalt and phosphate, and between labile cobalt and phosphate, demonstrating a strong biological influence on cobalt cycling. Along the western margin off the North American coast, this correlation with phosphate was no longer observed and instead a relationship between cobalt and salinity was observed, reflecting the importance of

  16. Cobalt dinitrosoalkane complexes in the C-H functionalization of olefins.

    Science.gov (United States)

    Schomaker, Jennifer M; Boyd, W Christopher; Stewart, Ian C; Toste, F Dean; Bergman, Robert G

    2008-03-26

    The use of cobalt dinitrosoalkane complexes in the C-H functionalization of alkenes has been demonstrated. Reaction of a series of alkenes with Me4CpCo(CO)2 in the presence of NO generates intermediate cobalt dinitrosoalkane complexes that can be deprotonated alpha to the nitrosyl group and added to various Michael acceptors. The resultant products can then undergo retrocycloaddition reactions in the presence of the original alkene to regenerate the starting cobalt dinitrosoalkane complex and release the functionalized alkene.

  17. Towards the elimination of excessive cobalt supplementation in racing horses: A pharmacological review.

    Science.gov (United States)

    Kinobe, Robert T

    2016-02-01

    Cobalt is an essential trace element for many vital physiological functions. Cobalt is also known to stabilise hypoxia-inducible transcription factors leading to increased expression of erythropoietin which activates production of red blood cells. This implies that cobalt can be used to enhance aerobic performance in racing horses. If this becomes a pervasive practice, the welfare of racing animals would be at risk because cobalt is associated with cardiovascular, haematological, thyroid gland and reproductive toxicity as observed in laboratory animals and humans. It is expected that similar effects may manifest in horses but direct evidence on equine specific effects of cobalt and the corresponding exposure conditions leading to such effects is lacking. Available pharmacokinetic data demonstrates that intravenously administered cobalt has a long elimination half-life (42-156 h) and a large volume of distribution (0.94 L/kg) in a horse implying that repeated administration of cobalt would accumulate in tissues over time attaining equilibrium after ~9-33 days. Based on these pharmacokinetic data and surveys of horses post racing, threshold cobalt concentrations of 2-10 μg/L in plasma and 75-200 μg/L in urine have been recommended. However, there is no clearly defined, presumably normal cobalt supplementation regimen for horses and characterisation of potential adverse effects of any established threshold cobalt concentrations has not been done. This review outlines the strengths and limitations of the existing literature on the pharmacological effects of cobalt in horses with some recommendations on what gaps to bridge to enable the determination of optimal threshold cobalt concentrations in racing horses. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

    OpenAIRE

    Gary Jacobs; Wenping Ma; Burtron H. Davis

    2014-01-01

    This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing...

  19. Manganese substituted cobalt ferrite magnetostrictive materials for magnetic stress sensor applications

    OpenAIRE

    Paulsen, J. A.; Ring, A. P.; Lo, C. C. H.; Snyder, John Evan; Jiles, David

    2005-01-01

    Metal bonded cobalt ferrite composites have been shown to be promising candidate materials for use in magnetoelastic stress sensors, due to their large magnetostriction and high sensitivity of magnetization to stress. However previous results have shown that below 60 °C the cobalt ferrite material exhibits substantial magnetomechanical hysteresis. In the current study, measurements indicate that substituting Mn for some of the Fe in the cobalt ferrite can lower the Curie temperature of the ma...

  20. A laboratory and field evaluation of the mobility of cobalt-60/EDTA

    International Nuclear Information System (INIS)

    Jones, T.L.; Gee, G.W.; Kirkham, R.R.; Swanson, J.L.

    1983-01-01

    We have observed a time and soil type dependence in the ability of the organic complexant EDTA to keep cobalt-60 in solution. Test results indicate that short-term adsorption tests lasting 5 days or less can be misleading. In short-term tests using cobalt-60/EDTA and soil from the Hanford site, low sorption in batch tests and high mobility in column tests were observed. During long-term batch test using cobalt-60/EDTA, the percentage of cobalt remaining in solution decreased from 90% after 7 days to less than 10% after 500 days. In laboratory and field column tests where low water flow rates allowed long contact time, virtually no cobalt movement was observed even though in the field test tritium was transported over 4 meters. Long-term batch tests using cobalt-60/EDTA and soil from Savannah River burial grounds showed that cobalt remainin in solution dropped to 30% of the total cobalt added after 5 days and to less than 1% after 15 days. Batch tests using soil from Oak Ridge burial grounds were less dramatic showing cobalt in solution decreasing from 90% after 5 days to 70% after 35 days. The cobalt-60/EDTA complex appears to be dissociating and leaving uncomplexed cobalt which is readily sorbed. The dissociation seems to be rather complete in Hanford and Savannah River soil but limited in the Oak Ridge soil. The implication to waste management is that the potential for transport of cobalt by EDTA may not be as serious at all burial sites as once thought

  1. An Economic Analysis of Electron Accelerators and Cobalt-60 for Irradiating Food

    OpenAIRE

    Morrison, Rosanna Mentzer

    1989-01-01

    Average costs per pound of irradiating food are similar for the electron accelerator and cobalt-60 irradiators analyzed in this study, but initial investment costs can vary by $1 million. Irradiation costs range from 0.5 to 7 cents per pound and decrease as annual volumes treated increase. Cobalt-60 is less expensive than electron beams for annual volumes below 50 million pounds. For radiation source requirements above the equivalent of 1 million curies of cobalt-60, electron beams are more e...

  2. Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

    OpenAIRE

    Roa Rovira, Joan Josep; Jiménez Piqué, Emilio; Tarragó Cifre, Jose María; Zivcec, Maria; Broeckmann, C.; Llanes Pitarch, Luis Miguel

    2014-01-01

    A cobalt-base solid solution is the most used binder for hardmetals (WC–Co cemented carbides) in a wide range of industrial applications. In the composite material such cobalt alloy is surrounded by hard carbides grains; thus, a direct evaluation of its intrinsic mechanical properties is not an easy task. In order to overcome this inconvenience, a model cobalt alloy with a composition similar to that exhibited by typical hardmetal binder (containing W and C in solid solution) was processed fo...

  3. DDT performance of energetic cobalt coordination compounds. [Dozen of compounds similar to 2-(5-cyanotetrazolato)pentaaminecobalt perchlorate, trinitrotriamine cobalt, dinitrobis(ethylenediamine) cobalt perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Lieberman, M.L.; Fleming, W.

    1986-01-01

    The compound 2-(5-cyanotetrazolato)pentaamminecobalt(III) perchlorate (CP) has been utilized in low-voltage detonators because it reliably undergoes deflagration-to-detonation transition (DDT). In the present investigation, we have compared the performance of over a dozen similar compounds. These compounds all have cobalt as the coordinating metal, most are ammine complexes, and all except one incorporate the perchlorate anion as an oxidizer. Chemical factors such as fuel-to-oxidizer ratio, trigger group, and organic content have been varied. 18 refs., 7 figs., 2 tabs.

  4. Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties

    Czech Academy of Sciences Publication Activity Database

    Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

    2017-01-01

    Roč. 499, AUG (2017), s. 138-144 ISSN 0021-9797 Institutional support: RVO:61388980 ; RVO:61389013 ; RVO:61388955 Keywords : Hydroxide nanosheets * Delamination * Exfoliation * Layered nickel hydroxide * Layered cobalt hydroxide * Electrode material Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W); CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Inorganic and nuclear chemistry; Physical chemistry (UFCH-W); Polymer science (UMCH-V) Impact factor: 4.233, year: 2016

  5. CARDIOPROTECTIVE EFFECT OF NATIVE ANTIHYPOXANTS IN EXPERIMENTAL COBALT CARDIOMYOPATHY

    Directory of Open Access Journals (Sweden)

    I. V. Zadnipryany

    2016-01-01

    Full Text Available The aim of research – the study of cardioprotective properties of antioxidants in terms of histotoxic hypoxia under experimental conditions.Materials and methods. The study was conducted on 20 adult male Wistar rats divided into 3 experimental groups, which for 7 days were intraperitoneally injected aqueous CoCl2 solution at a dose of 60 mg/kg. Rats of the first experimental group (n = 6 had no administered drug correction, a the second group of animals (n = 7 after the cobalt chloride daily injections was administered intragastrically Enoant Premium aqueous solution at a dose of 2.5 ml / kg, along with 0.05 ml of water, the rats the third test group (n = 7 after the administration of cobalt chloride were exposed to cytoflavin correction concentrate and grape polyphenols administered simultaneously. Studies of myocardium were conducted using light and electron microscopy.Results of the research. The result of the cobalt toxic effect on the heart of animals in experiments lead to the development of cardiomyopathy, which required timely cardioprotection. Morphological changes in the second group of rats, despite a slight improvement compared with the group without correction,were characterized, above all, by uneven from mild to severe edema of the myocardium. Structure of myocardium observed in the third group of male rats after cobalt intoxication, generally reflected a tendency to minimization of the extent of the damage, which was manifested in the form of normalization of cell structures and muscle fibers.Conclusion. The administration of succinic acid derivatives combined with the grape polyphenols demonstrated vivid cytoprotective properties evidenced by mostly preserved myocardium structure in rats exposed to histotoxic hypoxia in comparison to only administration of plant polyphenols group. 

  6. Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

    Indian Academy of Sciences (India)

    of 60 mV were observed at. 100 mV s. −1 for CoOx−MWNT/GCE. An anodic peak at. 100 mV attributed to Co(II)/Co(III) redox transition associated with the electrode surface. The cathodic peak at 20 mV corre- spond to the reduction of various cobalt oxide species formed during the anodic sweep. The stability of the modified ...

  7. Effect of cobalt substitution on magnetic and transport properties of ...

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 34; Issue 2. Effect of cobalt substitution on magnetic and transport properties of Nd0.5Sr0.5Mn1−CoO3 ( = 0.1, 0.3 and 0.5). Saket Asthana. Volume 34 Issue 2 April 2011 pp 279-282 ...

  8. PREPARATION OF NICKEL - COBALT SPINEL OXIDES NixCO3 ...

    African Journals Online (AJOL)

    ABSTRACT. A comparative study of two electro-physical properties (porosity and electrical conductivity) of binary nickel cobalt oxides electrodes with spinels mixed oxides NixCo3-xO4 as active matter, was carried out. Four different routes were used to prepare spinel-type NixCo3-xO4 (0 ≤ x ≤. 2.5) compounds in order to ...

  9. Ferric and cobaltous hydroacid complexes for forward osmosis (FO) processes

    KAUST Repository

    Ge, Qingchun

    2014-07-01

    Cupric and ferric hydroacid complexes have proven their advantages as draw solutes in forward osmosis in terms of high water fluxes, negligible reverse solute fluxes and easy recovery (Ge and Chung, 2013. Hydroacid complexes: A new class of draw solutes to promote forward osmosis (FO) processes. Chemical Communications 49, 8471-8473.). In this study, cobaltous hydroacid complexes were explored as draw solutes and compared with the ferric hydroacid complex to study the factors influencing their FO performance. The solutions of the cobaltous complexes produce high osmotic pressures due to the presence of abundant hydrophilic groups. These solutes are able to dissociate and form a multi-charged anion and Na+ cations in water. In addition, these complexes have expanded structures which lead to negligible reverse solute fluxes and provide relatively easy approaches in regeneration. These characteristics make the newly synthesized cobaltous complexes appropriate as draw solutes. The FO performance of the cobaltous and ferric-citric acid (Fe-CA) complexes were evaluated respectively through cellulose acetate membranes, thin-film composite membranes fabricated on polyethersulfone supports (referred as TFC-PES), and polybenzimidazole and PES dual-layer (referred as PBI/PES) hollow fiber membranes. Under the conditions of DI water as the feed and facing the support layer of TFC-PES FO membranes (PRO mode), draw solutions at 2.0M produced relatively high water fluxes of 39-48 LMH (Lm-2hr-1) with negligible reverse solute fluxes. A water flux of 17.4 LMH was achieved when model seawater of 3.5wt.% NaCl replaced DI water as the feed and 2.0M Fe-CA as the draw solution under the same conditions. The performance of these hydroacid complexes surpasses those of the synthetic draw solutes developed in recent years. This observation, along with the relatively easy regeneration, makes these complexes very promising as a novel class of draw solutes. © 2014 Elsevier Ltd.

  10. Protective Agent-Free Synthesis of Colloidal Cobalt Nanoparticles

    International Nuclear Information System (INIS)

    Balela, M. D. L.; Lockman, Z.; Azizan, A.; Matsubara, E.; Amorsolo, A. V. Jr.

    2010-01-01

    Spherical colloidal cobalt (Co) nanoparticles of about 2-7 nm were synthesized by hydrazine reduction in ethylene glycol at 80 deg. C. The mean diameter of the Co nanoparticles was varied to some extent by changing the pH, temperature, Co(II) chloride hexahydrate concentration, and amount of hydrazine. The Co particle size was reduced by decreasing Co(II) chloride concentration and increasing amount of hydrazine.

  11. In vivo incorporation of cobalt into Propionibacterium shermanii superoxide dismutase.

    Science.gov (United States)

    Meier, B; Sehn, A P; Sette, M; Paci, M; Desideri, A; Rotilio, G

    1994-07-18

    Propionibacterium shermanii, an aerotolerant anaerobic bacterium, has already been shown to incorporate, depending on the metal supplementation to the medium, either iron or manganese or copper into the same superoxide dismutase protein. The in vivo incorporation of cobalt in the same superoxide dismutase was obtained in an iron-, manganese- and copper-depleted medium. The protein was isolated and characterized by NMR which offers the possibility to identify the amino acid residues at the active site exploiting isotropically shifted proton resonance.

  12. Cobalt alloy ion sources for focused ion beam implantation

    Energy Technology Data Exchange (ETDEWEB)

    Muehle, R.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zimmermann, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Cobalt alloy ion sources have been developed for silicide formation by focused ion beam implantation. Four eutectic alloys AuCo, CoGe, CoY and AuCoGe were produced by electron beam welding. The AuCo liquid alloy ion source was investigated in detail. We have measured the emission current stability, the current-voltage characteristics, and the mass spectrum as a function of the mission current. (author) 1 fig., 2 refs.

  13. University Internationalization and University Autonomy

    DEFF Research Database (Denmark)

    Turcan, Romeo V.; Gulieva, Valeria

    2016-01-01

    Turcan and Gulieva deepen our theoretical understanding of the process of university internationalisation by exploring the relationship between university internationalisation and university autonomy. They conjecture that the process of university internationalisation and its sustainability are d...

  14. Thin films of tetrafluorosubstituted cobalt phthalocyanine: Structure and sensor properties

    Energy Technology Data Exchange (ETDEWEB)

    Klyamer, Darya D.; Sukhikh, Aleksandr S. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2 (Russian Federation); Krasnov, Pavel O. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Gromilov, Sergey A. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2 (Russian Federation); Morozova, Natalya B. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Basova, Tamara V., E-mail: basova@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2 (Russian Federation)

    2016-05-30

    Highlights: • Thin films of tetrafluorosubstituted cobalt phthalocyanine were studied. • The effect of fluorine substituents to the films structure and properties was verified. • The sensor response of tetrafluorosubstituted phthalocyanine toward NH{sub 3} was studied. • The structure of analyte/phthalocyanine complex was analysed using DFT calculations. - Abstract: In this work, thin films of tetrafluorosubstituted cobalt phthalocyanine (CoPcF{sub 4}) were prepared by organic molecular beam deposition and their structure was studied using UV–vis, polarization dependent Raman spectroscopy, XRD and atomic force microscopy. Quantum chemical calculations (DFT) have been employed in order to determine the detailed assignment of the bands in the CoPcF{sub 4} IR and Raman spectra. The electrical sensor response of CoPcF{sub 4} films to ammonia vapours was investigated and compared with that of unsubstituted cobalt phthalocyanine films. In order to explain the difference in sensitivity of the unsubstituted and fluorinated phthalocyanines to ammonia, the nature and properties of chemical binding between CoPc derivatives and NH{sub 3} were described by quantum-chemical calculations utilizing DFT method. The effect of post-deposition annealing on surface morphology and gas sensing properties of CoPcF{sub 4} films was also studied.

  15. Femtosecond pulsed laser deposition of cobalt ferrite thin films

    Science.gov (United States)

    Dascalu, Georgiana; Pompilian, Gloria; Chazallon, Bertrand; Caltun, Ovidiu Florin; Gurlui, Silviu; Focsa, Cristian

    2013-08-01

    The insertion of different elements in the cobalt ferrite spinel structure can drastically change the electric and magnetic characteristics of CoFe2O4 bulks and thin films. Pulsed Laser Deposition (PLD) is a widely used technique that allows the growth of thin films with complex chemical formula. We present the results obtained for stoichiometric and Gadolinium-doped cobalt ferrite thin films deposited by PLD using a femtosecond laser with 1 kHz repetition rate. The structural properties of the as obtained samples were compared with other thin films deposited by ns-PLD. The structural characteristics and chemical composition of the samples were investigated using profilometry, Raman spectroscopy, X-Ray diffraction measurements and ToF-SIMS analysis. Cobalt ferrite thin films with a single spinel structure and a preferential growth direction have been obtained. The structural analysis results indicated the presence of internal stress for all the studied samples. By fs-PLD, uniform thin films were obtained in a short deposition time.

  16. Improvement of the oxidation stability of cobalt nanoparticles

    Directory of Open Access Journals (Sweden)

    Celin Dobbrow

    2012-01-01

    Full Text Available In order to enhance the resistance of cobalt nanoparticles to oxidation in air, the impact of different stabilization strategies on the isothermal oxidation of particle dispersions and powders was kinetically investigated and compared to as-prepared particle preparations. A post-synthesis treatment with different alcohols was employed, and we also investigate the influence of two different polymer shells on the oxidation process. We found a parabolic decrease of the magnetization for all particle charges, indicating that the process is dominated by a diffusion of oxygen to the cobalt core and a radial growth of the oxide layer from the particle surface to the core. A significant deceleration of the oxidation process was observed for all alcohol-passivated particle preparations, and this resulted finally in a stagnation effect. The stabilizing effect increases in the sequence Co@OA/MeOH < Co@OA/EtOH < Co@OA/iPrOH. For polymer-coated particle preparations Co@PCL and Co@PS, the deceleration was even more pronounced. The results demonstrate that cobalt nanoparticles can effectively be protected against oxidation in order to improve their mid- to longterm stability.

  17. Nationwide survey of cobalt-60 teletherapy. Final report

    International Nuclear Information System (INIS)

    Thompson, D.L.; Kearly, F.E.; Wyckoff, H.O.; Gitlin, J.N.; Reffit, E.B.; Shangold, E.J.

    1980-08-01

    The Bureau of Radiological Health and the National Bureau of Standards conducted a nationwide survey of cobalt-60 teletherapy facilities to determine their accuracy in delivery of a prescribed dose to a phantom. Participation was obtained from 684 respondents or 75 percent of US facilities. For each cobalt-60 unit the average dose recorded on five dosimeters was within 5 percent of the prescribed value for 83 percent of the respondents and only exceeded a 10 percent difference for 3 percent of the respondents. Sufficient information for reconstruction of dose calculations was available for 87 percent of the participating facilities. Of these reconstructed calculations, 56 percent were within 1 percent of the prescribed dose of 300 rads. The analysis of data from the survey showed that better performance were related to a number of factors. Among these were expressing the machine calibration in terms of dose rate, performing the machine calibration on an annual basis, and correcting for source decay on a monthly basis. Larger facilities achieved better results than smaller facilities when calculating the absorbed dose rate. Also, each 4 machine characteristics (isocentric mounting, short exposure time, high normalized output, and long treatment distance) were related to better performance with regard to both dosimeter readings and calculated doses. Larger facilities were more likely to be using a cobalt-60 unit having those characteristics

  18. Radiation dose distributions due to sudden ejection of cobalt device

    International Nuclear Information System (INIS)

    Abdelhady, Amr

    2016-01-01

    The evaluation of the radiation dose during accident in a nuclear reactor is of great concern from the viewpoint of safety. One of important accident must be analyzed and may be occurred in open pool type reactor is the rejection of cobalt device. The study is evaluating the dose rate levels resulting from upset withdrawal of co device especially the radiation dose received by the operator in the control room. Study of indirect radiation exposure to the environment due to skyshine effect is also taken into consideration in order to evaluate the radiation dose levels around the reactor during the ejection trip. Microshield, SHLDUTIL, and MCSky codes were used in this study to calculate the radiation dose profiles during cobalt device ejection trip inside and outside the reactor building. - Highlights: • This study aims to calculate the dose rate profiles after cobalt device ejection from open-pool-type reactor core. • MicroShield code was used to evaluate the dose rates inside the reactor control room. • McSKY code was used to evaluate the dose rates outside the reactor building. • The calculated dose rates for workers are higher than the permissible limits after 18 s from device ejection.

  19. The structural and magnetic properties of dual phase cobalt ferrite.

    Science.gov (United States)

    Gore, Shyam K; Jadhav, Santosh S; Jadhav, Vijaykumar V; Patange, S M; Naushad, Mu; Mane, Rajaram S; Kim, Kwang Ho

    2017-05-31

    The bismuth (Bi 3+ )-doped cobalt ferrite nanostructures with dual phase, i.e. cubic spinel with space group Fd3m and perovskite with space group R3c, have been successfully engineered via self-ignited sol-gel combustion route. To obtain information about the phase analysis and structural parameters, like lattice constant, Rietveld refinement process is applied. The replacement of divalent Co 2+ by trivalent Bi 3+ cations have been confirmed from energy dispersive analysis of the ferrite samples. The micro-structural evolution of cobalt ferrite powders at room temperature under various Bi 3+ doping levels have been identified from the digital photoimages recorded using scanning electron microscopy. The hyperfine interactions, like isomer shift, quadrupole splitting and magnetic hyperfine fields, and cation distribution are confirmed from the Mossbauer spectra. Saturation magnetization is increased with Bi 3+ -addition up to x = 0.15 and then is decreased when x = 0.2. The coercivity is increased from 1457 to 2277 G with increasing Bi 3+ -doping level. The saturation magnetization, coercivity and remanent ratio for x = 0.15 sample is found to be the highest, indicating the potential of Bi 3+ -doping in enhancing the magnetic properties of cobalt ferrite.

  20. Poorly soluble cobalt oxide particles trigger genotoxicity via multiple pathways.

    Science.gov (United States)

    Uboldi, Chiara; Orsière, Thierry; Darolles, Carine; Aloin, Valérie; Tassistro, Virginie; George, Isabelle; Malard, Véronique

    2016-02-03

    Poorly soluble cobalt (II, III) oxide particles (Co3O4P) are believed to induce in vitro cytotoxic effects via a Trojan-horse mechanism. Once internalized into lysosomal and acidic intracellular compartments, Co3O4P slowly release a low amount of cobalt ions (Co(2+)) that impair the viability of in vitro cultures. In this study, we focused on the genotoxic potential of Co3O4P by performing a comprehensive investigation of the DNA damage exerted in BEAS-2B human bronchial epithelial cells. Our results demonstrate that poorly soluble Co3O4P enhanced the formation of micronuclei in binucleated cells. Moreover, by comet assay we showed that Co3O4P induced primary and oxidative DNA damage, and by scoring the formation of γ-H2Ax foci, we demonstrated that Co3O4P also generated double DNA strand breaks. By comparing the effects exerted by poorly soluble Co3O4P with those obtained in the presence of soluble cobalt chloride (CoCl2), we demonstrated that the genotoxic effects of Co3O4P are not simply due to the released Co(2+) but are induced by the particles themselves, as genotoxicity is observed at very low Co3O4P concentrations.

  1. Recovery of molybdenum and cobalt powders from spent hydrogenation catalyst

    International Nuclear Information System (INIS)

    Rabah, M.A.; Hewaidy, I.F.; Farghaly, F.E.

    1996-01-01

    Free powders as well as compact shapes of molybdenum and cobalt have been successfully recovered from spent hydrogenation and desulphurization catalysts. A process flow sheet was followed involving crushing, milling, particle sizing, hydrometallurgical acid leaching roasting of the obtained salts in an atmospheric oxygen to obtain the respective oxides. These were reduced by hydrogen gas at 110 degree C and 900 degree C respectively. Parameters affecting the properties of the products and the recovery efficiency value such as acid concentration, particle diameter of the solid catalyst, temperature time under a constant mass flow rate the hydrogen gas, have been investigated. A mixture of concentration.sulphuric and nitric acids (3:1 by volume) achieved adequate recovery of both metals. The latter increased with the increase in acid concentration, time up 10 3 hours and temperature: 100 degree C and with the decrease in particle diameter of the spent catalyst. The PH of the obtained filtrate was adjusted to 2 with ammonia to precipitate insoluble ammonium molybdate and a solution of cobalt sulphate. Cobalt hydroxide can be precipitate from the latter solution at a PH = 7.6 using excess ammonium hydroxide solution. The obtained results showed that the metallic products are technically pure meeting the standard specifications. Compact shapes of molybdenum acquire density values increasing with the increase of the pressing load whereby a maximum density value of 2280 kg/m 3 is attained at 0.75 MPa. Maximum recovery efficiency amounts to 96%. 10 figs., 3 tabs

  2. Synthesis and characterization of cobalt sulfide nanoparticles by sonochemical method

    Science.gov (United States)

    Muradov, Mustafa B.; Balayeva, Ofeliya O.; Azizov, Abdulsaid A.; Maharramov, Abel M.; Qahramanli, Lala R.; Eyvazova, Goncha M.; Aghamaliyev, Zohrab A.

    2018-03-01

    Convenient and environmentally friendly synthesis of Co9S8/PVA, CoxSy/EG and CoxSy/3-MPA nanocomposites were carried out in the presence of ultrasonic irradiation by the liquid phase synthesis of the sonochemical method. For the synthesis, cobalt acetate tetrahydrate [Co(CH3COO)2·4H2O] and sodium sulfide (Na2S·9H2O) were used as a cobalt and sulfur precursor, respectively. Polyvinyl alcohol (PVA), ethylene glycol (EG) and 3-mercaptopropionic acid (3-MPA) were used as a capping agent and surfactant. The structural, optical properties and morphology of nanocomposites were characterized using X-ray diffractometer (XRD), Ultraviolet/Visible Spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optical band gap of Co9S8/PVA is 1.81 eV and for CoxSy/EG is 2.42 eV, where the direct band gap of bulk cobalt sulfide is (0.78-0.9 eV). The wide band gap indicates that synthesised nanocomposites can be used in the fabrication of optical and photonic devices. The growth mechanisms of the Co9S8, CoS2 and Co3S4 nanoparticles were discussed by the reactions. The effects of sonication time and annealing temperature on the properties of the nanoparticles have been studied in detail.

  3. Cobalt Cardiomyopathy: A Critical Reappraisal in Light of a Recent Resurgence.

    Science.gov (United States)

    Packer, Milton

    2016-12-01

    Cobalt can cause a distinctive, rapidly progressive and reversible depression of cardiac systolic function, which is readily distinguished from other causes of cardiomyopathy. Patients present with the subacute onset of severe heart failure, which is accompanied by hypotension and cyanosis, pericardial effusion, low voltage on the electrocardiogram, marked elevation of serum enzymes, and lactic acidosis. They typically have a history of lethargy, anorexia, and weight loss in the months preceding the illness and exhibit other evidence of cobalt's effects on the body (eg, polycythemia and goiter). The course of cobalt-related cardiomyopathy may be progressive and fatal, but those who survive and cease exposure generally demonstrate complete resolution of symptoms and recovery of cardiac function. Patients presenting with rapid onset of cardiomyopathy, who also exhibit polycythemia, pericardial effusion, or goiter should be evaluated for cobalt exposure. Exposure can be confirmed by the measurement of cobalt in the serum, but serum levels of the ion are not reliably predictive of clinical cardiotoxicity. The clinical emergence of cobalt cardiomyopathy seems to require the coexistence of one or more cofactors, particularly a low-protein diet, thiamine deficiency, alcoholism, and hypothyroidism. As the medicinal use of cobalt has waned and measures to reduce industrial exposure have been implemented, subacute cobalt-related cardiomyopathy had become rare. However, reports describing classical features of the disease have recently surged among patients with a malfunctioning cobalt-alloy hip prosthesis. © 2016 American Heart Association, Inc.

  4. Fatal cobalt toxicity after total hip arthroplasty revision for fractured ceramic components.

    Science.gov (United States)

    Fox, Kimberly A; Phillips, Todd M; Yanta, Joseph H; Abesamis, Michael G

    2016-11-01

    Post-arthroplasty metallosis, which refers to metallic corrosion and deposition of metallic debris in the periprosthetic soft tissues of the body, is an uncommon complication. Systemic cobalt toxicity post-arthroplasty is extremely rare. The few known fatal cases of cobalt toxicity appear to be a result of replacing shattered ceramic heads with metal-on-metal or metal-on-polyethylene implants. Friction between residual shards of ceramic and cobalt-chromium implants allows release of cobalt into the synovial fluid and bloodstream, resulting in elevated whole blood cobalt levels and potential toxicity. This is a single patient chart review of a 60-year-old woman with prior ceramic-on-ceramic right total hip arthroplasty complicated by fractured ceramic components and metallosis of the joint. She underwent synovectomy and revision to a metal-on-polyethylene articulation. Ten months post-revision, she presented to the emergency department (ED) with right hip pain, dyspnea, worsening hearing loss, metallic dysgeusia, and weight loss. Chest CTA revealed bilateral pulmonary emboli (PE), and echocardiogram revealed new cardiomyopathy with global left ventricular hypokinesis with an ejection fraction (EF) of 35-40% inconsistent with heart strain from PE. Whole blood cobalt level obtained two days into her admission was 424.3 mcg/L and 24-h urine cobalt level was 4830.5 mcg/L. Although the patient initially clinically improved with regard to her PE and was discharged to home on hospital day 5, she returned 10 days later with a right hip dislocation and underwent closed reduction of the hip. The patient subsequently decompensated, developing cardiogenic shock, and respiratory failure. She went into pulseless electrical activity (PEA) and expired. Autopsy revealed an extensive metallic effusion surrounding the right hip prosthesis that tested positive for cobalt (41,000 mcg/L). There was also cobalt in the heart muscle tissue (2.5 mcg/g). A whole blood cobalt level

  5. Characterization of composite materials of electroconductive polymer and cobalt as electrocatalysts for the oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Millan, W.; Toledano Thompson, T.; Smit, Mascha A. [Centro de Investigacion Cientifica de Yucatan (CICY), Unidad de Materiales, Calle 43 No. 130, Col. Chuburna de Hidalgo, 97200 Merida, Yucatan (Mexico); Arriaga, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C. (CIDETEQ), Parque Tecnologico Queretaro, 76700 Queretaro Sanfandila, Queretaro (Mexico)

    2009-01-15

    Platinum-free electrocatalysts based on electroconductive polymer, modified with cobalt, were prepared and characterized for the oxygen reduction reaction (ORR). The carbon-supported materials were: carbon/polyaniline/cobalt, carbon/polypyrrole/cobalt and carbon/poly(3-methylthiophene)/cobalt. Also the corresponding cobalt-free precursors were studied. EDAX studies show that in cobalt-modified catalysts, significant percentages of cobalt, between 5 and 7% in weight, are present. FTIR, TGA, and EDAX studies confirmed that the addition of cobalt modifies the chemical structure of C-Pani, C-Ppy, and C-P3MT materials. Cyclic voltammetry shows reduction peaks corresponding to the ORR for all materials and kinetic parameters were calculated based on lineal voltammetry using RDE at different rotating speeds. It was found that C-P3MT-Co has highest exchange current densities, followed by C-Ppy and C-Ppy-Co. All samples have Tafel slopes between -110 and -120 V/dec, indicating that the first electron transfer is the decisive step in the global ORR. Potentiostatic tests showed an adequate stability of cobalt-modified samples in acid medium at ORR potentials. Based on the potential range at which ORR occurs, the exchange current density and stability tests, it is concluded that the best material for potential application as fuel cell cathode catalyst is C-Ppy-Co. (author)

  6. Preparation and characteristics of core-shell structure cobalt/silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fu Wuyou [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Yang Haibin [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China) and Henan Polytechnic University, Hennan Jiaozuo 454000 (China)]. E-mail: yanghb@jlu.edu.cn; Hari-Bala [College of Chemistry, Jilin University, Changchun 130023 (China); Liu Shikai [Henan Polytechnic University, Hennan Jiaozuo 454000 (China); Li, Minghui [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Zou Guangtian [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)

    2006-12-10

    The silica nanolayer with different thickness was coated on the spherical cobalt nanoparticles (an average diameter of 67 nm) to form core-shell structure by the controlled hydrolysis and condensation of tetraethyl orthosilicate (TEOS). This coating process was based on the use of silane coupling agent 3-mercaptopropyltrimethoxysilane (HS-(CH{sub 2}){sub 3}Si(OCH{sub 3}){sub 3}, MPTS) as a primer to render the cobalt surface vitreophilic, thus rendering cobalt surface compatible with silica. The control over the silica coating layer thickness can be achieved by varying the reaction time. The cobalt nanoparticles and the cobalt coated with silica shell were confirmed by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) was used to gain insight into the way in which the MPTS is bound to the surface of the cobalt nanoparticles. Result of the thermogravimetric analysis (TGA) and differential thermal analysis (DTA) indicate that the thermal stability of cobalt/silica is better than that of pure cobalt nanoparticles. Magnetic properties of these powders have been evaluated. These cobalt/silica core-shell nanoparticles can be utilized as precursors for making property-tunable magnetic nanoparticles, thin films, and multilayered core-shell structure nanocomposites.

  7. Research about combination of Gamma Knife and cobalt-60 radiation therapy to treat hypophysoma

    International Nuclear Information System (INIS)

    Xing Yueming; Zhao Xinping; Song Xiang; Wu Wei; Huang Bai

    2003-01-01

    Objective: To probe the therapeutic effectiveness of combination of Gamma Knife and cobalt-60 radiotherapy. Methods: 80 Hypophysoma patients who have been randomly grouped into two groups. Combination of Gamma Knife and cobalt-60 radiotherapy group and single Gamma knife group. Results: The therapeutic effectiveness of combination of Gamma Knife and cobalt-60 radiation therapy group was higher than that of single Gamma Knife group. Conclusion: The hospital that treat Hypophysoma with single Gamma Knife should add cobalt-60 radiotherapy in order to increase the local Hypophysoma dose

  8. PENYERAPAN COBALT-60 DARI AIR OLEH TANAMAN KIAPU (Pistia stratiotes L.)

    OpenAIRE

    Lailatul Nuzzulul Safitri; Poppy Intan Tjahaja; Ida Bagus Made Suryatika

    2015-01-01

    Has conducted research Cobalt-60 radionuclide uptake by plants kiapu (Pistia stratiotes L.) found in many waters. The purpose of the study was to determine the value of the transfer factor on plant kiapu to Cobalt-60 in water. The study was conducted by growing plants on media kiapu gutter water in pots with the height 35 cm and diameter 11,5 cm containing Cobalt-60. The amount of Cobalt - 60 is absorbed and accumulated by the plant parts, i.e. roots and leaves, was observed by measuring the ...

  9. Competitive Adsorption-Assisted Formation of One-Dimensional Cobalt Nanochains with High CO Hydrogenation Activity

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xin [State; Ren, Zhibo [State; Institute; Zhu, Xiaolin [State; Zhang, Qinwei [State; Mei, Donghai [Institute; Chen, Biaohua [State

    2017-10-31

    In the present work, cobalt nanochains have been successfully synthesized by a novel co assisted self-assembling formation strategy. A dramatic morphology transformation from cobalt nanoparticles to nanochains are observed when co molecules were introduced into the synthetic system. DFT calculations further confirm that competitive co-adsorbed co and oleylamine over the cobalt nanoparticles facilitates the formation of cobalt nanochains, which show higher co hydrogenation performance. The present work provides a new strategic and promising method for controllable synthesis of catalyst nanomaterials with the preferred surface structure and morphology.

  10. The mechanism in the poisoning of anion-exchange resins by cobalt cyanide

    International Nuclear Information System (INIS)

    Fleming, C.A.; Hancock, R.D.

    1979-01-01

    The complex responsible for the poisoning of anion-exchange resins is identified as the anionic cobaltic pentacyanide mono aquo species. It is shown that, at high concentration, this species polymerizes in solutions of pH less than 9. A mechanism for poisoning is presented that involves adsorption of anionic cobalt cyanide by a normal ion-exchange process, followed by polymerization within the resin matrix to form complexes that are too large to diffuse readily through the resin pores. The effects of resin structure and functionality on the extent of cobalt poisoning are examined, and the effect of cobalt poisoning on the kinetics and equilibrium loading of uranium is discussed [af

  11. Testing of cobalt-free alloys for valve applications using a special test loop

    International Nuclear Information System (INIS)

    Benhamou, C.

    1992-01-01

    Considering that use of cobalt alloys should be avoided as far as possible in PWR components, a programme aimed at establishing the performance of cobalt-free alloys has been performed for valve applications, where cobalt alloys are mainly used. Referring to past work, two types of cobalt-free alloys were selected: Ni-Cr-B-Si and Ni-Cr-Fe alloys. Cobalt-free valves' behaviour has been evaluated comparatively with cobalt valves by implementation of a programme in a special PWR test loop. At the issue of the loop test programme, which included endurance, thermal shock and erosion tests, cobalt-free alloys candidate to replace cobalt alloys are proposed in relation with valve type (globe valve and swing check valve). The following was established: (i) Colmonoy 4-26 (Ni-Cr-B-Si alloy) and Cenium Z20 (Ni-Cr-Fe alloy) deposited by plasma arc process were found suitable for use in 3inch swing check valves; (ii) for integral parts acting as guide rings, Nitronic 60 and Cesium Z20/698 were tested successfully; (iii) for small-bore components such as 2inch globe valves, no solution can yet be proposed; introduction of cobalt-free alloys is dependent on the development of automatic advanced arc surfacing techniques applied to small-bore components

  12. Black and green pigments based on chromium-cobalt spinels

    Energy Technology Data Exchange (ETDEWEB)

    Eliziario, Sayonara A., E-mail: sayonaraea@iq.unesp.br [Departamento de Fisico-Quimica, Instituto de Quimica, UNESP - Univ Estadual Paulista, Araraquara, SP (Brazil); Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Andrade, Jeferson M. de [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Lima, Severino J.G. [Departamento de Engenharia Mecanica, CT, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Paskocimas, Carlos A. [Universidade Federal do Rio Grande do Norte, CT, Natal, RN (Brazil); Soledade, Luiz E.B. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Hammer, P.; Longo, E. [Departamento de Fisico-Quimica, Instituto de Quimica, UNESP - Univ Estadual Paulista, Araraquara, SP (Brazil); Souza, Antonio G.; Santos, Ieda M.G. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil)

    2011-09-15

    Highlights: {yields} Co(Co{sub 2-x}Cr{sub x})O{sub 4} powders with different chromium concentrations (x = 0, 0.25 and 1) were prepared by the polymeric precursor method. {yields} Co(CoCr)O{sub 4} and Co(Co{sub 1.75}Cr{sub 0.25})O{sub 4} displayed a dark color and CoCr{sub 2}O{sub 4} was green. {yields} The colors were related to the different oxidation states of Cr and Co. {yields} Cobalt enrichment result in an increasing presence of Co(III) and a decrease amount of Cr(VI). - Abstract: Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co{sub 2-x}Cr{sub x})O{sub 4} powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 deg. C. These powders were characterized by X-ray diffraction, infrared spectroscopy, colorimetry, UV-vis absorption and X-ray photoelectron spectroscopies. Even with the addition of chromium, the XRD patterns revealed that all powders crystallize in a single spinel cubic structure. The spinels with higher cobalt amount, Co(CoCr)O{sub 4} and Co(Co{sub 1.75}Cr{sub 0.25})O{sub 4}, displayed a dark color, without the Co{sup 3+} reduction observed in Co{sub 3}O{sub 4} between 900 and 950 deg. C. The spinel with higher chromium amount, CoCr{sub 2}O{sub 4}, was green. The colors were directly related to the occupation of tetrahedral and octahedral sites by the chromophores, as well as to the different oxidation states of chromium and cobalt. The different optical band gap values estimated from UV-vis spectra suggested the existence of intermediary energy levels within the band gap. X-ray photoelectron spectroscopy confirmed an increasing presence of Co(III) and a decreasing amount of Cr(VI) with cobalt enrichment.

  13. Electron transfer reactions of macrocyclic compounds of cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Heckman, R.A.

    1978-08-01

    The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

  14. New mixed valence defect dicubane cobalt(II)/cobalt(III) complex: Synthesis, crystal structure, photoluminescence and magnetic properties

    Science.gov (United States)

    Coban, Mustafa Burak; Gungor, Elif; Kara, Hulya; Baisch, Ulrich; Acar, Yasemin

    2018-02-01

    A new defect dicubane cobalt(II)/cobalt(III), [(CoII2CoIII2L42(H2O)(CH3COO)(CH3COOH]. 4H2O complex (1) where H2L = [1-(3-hydroxypropyliminomethyl)naphthalene-2-ol], has been synthesized and characterized by element analysis, FT-IR, solid UV-Vis spectroscopy and single crystal X-ray diffraction. The crystal structure determination shows a cationic tetrameric arrangement consisting of a defect dicubane core with two missing vertexes. Each cobalt ion has a distorted octahedral geometry with six coordinate ordered CoII and CoIII ions. The solid state photoluminescence properties of complex (1) and its ligand H2L have been investigated under UV light at 349 nm in the visible region. H2L exhibits blue emission while complex (1) shows red emission at room temperature. Variable-temperature magnetic susceptibility measurements on the complex (1) in the range 2-300 K indicate an antiferromagnetic interaction.

  15. Structural modifications under reactive atmosphere of cobalt catalysts; Modifications structurales sous atmospheres reactionnelles de catalyseurs a base de cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Ducreux, O.

    1999-11-23

    The purpose of this work was to develop in situ methods under reactive dynamic conditions (XRD and Fourier transform infrared spectroscopy) to describe the active phase structure in order to understand Fischer-Tropsch catalyst behaviour and improve the natural gas conversion process performance. Experiments were designed to correlate structural modifications with catalytic results. The effect of ruthenium used as a promoter has also been studied. The impregnation process increases cobalt-support interaction. The presence of ruthenium promoter reduces this effect. Interactions between Co{sub 3}O{sub 4} oxide and support play an important role in the reducibility of cobalt and in the resulting metal structure. This in turn strongly influences the catalytic behaviour. Our results show a close correlation between structure modification and reactivity in the systems studied. Cobalt metal and CO can react to form a carbide Co{sub 2}C under conditions close to those of the Fischer-Tropsch synthesis. This carbide formation seems to be related to a deactivation process. The presence of interstitial carbon formed by dissociation of CO is proposed as a key to understanding the mechanism of the Fischer-Tropsch reaction. A specific catalyst activation treatment was developed to increase the catalytic activity. This work permits correlation of materials structure with their chemical properties and demonstrates the contribution of in situ physico-chemical characterisation methods to describe solids under reactive atmosphere. (author)

  16. Lump Kinetic Analysis of Syngas Composition Effect on Fischer-Tropsch Synthesis over Cobalt and Cobalt-Rhenium Alumina Supported Catalyst

    OpenAIRE

    Dewi Tristantini; Ricky Kristanda Suwignjo

    2016-01-01

    This study investigated lump kinetic analysis of Fischer-Tropsch synthesis over Cobalt and Cobalt-Rhenium Alumina supported catalyst (Co/γ-Al2O3 and Co-Re/γ-Al2O3) at 20 bars and 483 K using feed gas with molar H2/CO ratios of 1.0 to 2.1. Syngas with H2/CO molar ratio of 1.0 represents syngas characteristic derived from biomass, while the 2.1 molar ratio syngas derived from coal. Rhenium was used as the promoter for the cobalt catalyst. Isothermal Langmuir adsorption mechanism was used to bui...

  17. Nanotoxicity of cobalt induced by oxidant generation and glutathione depletion in MCF-7 cells.

    Science.gov (United States)

    Akhtar, Mohd Javed; Ahamed, Maqusood; Alhadlaq, Hisham A; Alshamsan, Aws

    2017-04-01

    There are very few studies regarding the biological activity of cobalt-based nanoparticles (NPs) and, therefore, the possible mechanism behind the biological response of cobalt NPs has not been fully explored. The present study was designed to explore the potential mechanisms of the cytotoxicity of cobalt NPs in human breast cancer (MCF-7) cells. The shape and size of cobalt NPs were characterized by scanning and transmission electron microscopy (SEM and TEM). The crystallinity of NPs was determined by X-ray diffraction (XRD). The dissolution of NPs was measured in phosphate-buffered saline (PBS) and culture media by atomic absorption spectroscopy (AAS). Cytotoxicity parameters, such as [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT), neutral red uptake (NRU), and lactate dehydrogenase (LDH) release suggested that cobalt NPs were toxic to MCF-7 cells in a dose-dependent manner (50-200μg/ml). Cobalt NPs also significantly induced reactive oxygen species (ROS) generation, lipid peroxidation (LPO), mitochondrial outer membrane potential loss (MOMP), and activity of caspase-3 enzymes in MCF-7 cells. Moreover, cobalt NPs decreased intracellular antioxidant glutathione (GSH) molecules. The exogenous supply of antioxidant N-acetyl cysteine in cobalt NP-treated cells restored the cellular GSH level and prevented cytotoxicity that was also confirmed by microscopy. Similarly, the addition of buthionine-[S, R]-sulfoximine, which interferes with GSH biosynthesis, potentiated cobalt NP-mediated toxicity. Our data suggested that low solubility cobalt NPs could exert toxicity in MCF-7 cells mainly through cobalt NP dissolution to Co 2+ . Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. University Rankings

    Directory of Open Access Journals (Sweden)

    Telichenko Valeriy Ivanovich

    2014-06-01

    Full Text Available The article gives the analysis of university rankings and defines the differences in evaluation methods and indicators of world ranking agencies, presents new approaches to making global rankings. It defines the position of MGSU in Russian universities TOP-100 ranking. University rankings are not simply information, but the evaluation instrument of quality of education, initiating the improvement of ranking position. It’s important for Russian Universities claiming for higher positions in the world rankings. MGSU position in universities ranking made the University administration consider thoroughly the University positioning in the system of higher education, in the categories of education and science and among possible employers of the university graduates.

  19. A Highly Active and Selective Manganese Oxide Promoted Cobalt-on-Silica Fischer-Tropsch Catalyst

    NARCIS (Netherlands)

    den Breejen, Johan P.|info:eu-repo/dai/nl/304837318; Frey, Anne M.|info:eu-repo/dai/nl/341358851; Yang, Jia; Holmen, Anders; van Schooneveld, Matti M.|info:eu-repo/dai/nl/315032863; de Groot, Frank M. F.|info:eu-repo/dai/nl/08747610X; Stephan, Odile; Bitter, Johannes H.|info:eu-repo/dai/nl/160581435; de Jong, Krijn P.|info:eu-repo/dai/nl/06885580X

    A highly active and selective manganese oxide-promoted silica-supported cobalt catalyst for the Fischer-Tropsch reaction is reported. Co/MnO/SiO2 catalysts were prepared via impregnation of a cobalt nitrate and manganese nitrate precursor, followed by drying and calcination in an NO/He flow. The

  20. Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

    NARCIS (Netherlands)

    Hullebusch, van E.D.; Peerbolte, A.; Zandvoort, M.H.; Lens, P.N.L.

    2005-01-01

    The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH = 7) were loaded with nickel and cobalt in. adsorption experiments (monometal and competitive

  1. Radiometric trace analysis of cobalt with diethyldithiocarbamate-35S, or 203Hg

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1962-01-01

    Two radiometric methods for the determination of submugram amounts of cobalt are described. (A) Cobalt is extracted from an ammoniacal solution with a zinc-diethyldithiocarbamate-35S solution in chloroform. Excess reagent and interfering metals are removed with mercury(II) and cyanide. The 35S in

  2. Cobalt release and complications resulting from the use of dental prostheses.

    Science.gov (United States)

    Al-Imam, Hiba; Benetti, Ana R; Özhayat, Esben B; Pedersen, Anne M L; Johansen, Jeanne D; Thyssen, Jacob P; Jellesen, Morten S; Gotfredsen, Klaus

    2016-12-01

    Cobalt release from dental prostheses has been shown to elicit allergic reactions in cobalt-allergic patients. It is therefore important to investigate whether these prostheses are possible sources of sensitization. To assess (i) cobalt release from dental prostheses and (ii) allergic reactions to components of dental prostheses, and (iii) to investigate the oral mucosa for inflammation 1-5 years after insertion of the prostheses. Clinical oral examination was conducted in 66 patients with 84 dental prostheses. Cobalt release from 84 functional (used) and 32 non-functional (new) prostheses was investigated with the cobalt spot test. Contact allergy was assessed by patch testing. Smear tests for Candida spp. were performed in patients showing signs of inflammation of the oral mucosa. The prostheses were assessed for biological and technical complications. None of the functional prostheses released cobalt, whereas this was observed in 24 of 32 non-functional prostheses. None of the patients had contact allergy to cobalt. Of the 66 patients, 11 showed signs of inflammation of the oral mucosa, 2 had oral candidiasis, 16 had ill-fitting prostheses, and all had insufficient oral hygiene. Dental prostheses released cobalt during the fabrication stages, but not 1-5 years after insertion. No allergic reactions were observed. Signs of inflammation were related to candidiasis, insufficient oral hygiene, and ill-fitting prostheses. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Self-Subunit Swapping Occurs in Another Gene Type of Cobalt Nitrile Hydratase

    Science.gov (United States)

    Xia, Yuanyuan; Cui, Youtian; Kobayashi, Michihiko; Zhou, Zhemin

    2012-01-01

    Self-subunit swapping is one of the post-translational maturation of the cobalt-containing nitrile hydratase (Co-NHase) family of enzymes. All of these NHases possess a gene organization of , which allows the activator protein to easily form a mediatory complex with the α-subunit of the NHase after translation. Here, we discovered that the incorporation of cobalt into another type of Co-NHase, with a gene organization of , was also dependent on self-subunit swapping. We successfully isolated a recombinant NHase activator protein (P14K) of Pseudomonas putida NRRL-18668 by adding a Strep-tag N-terminal to the P14K gene. P14K was found to form a complex [α(StrepP14K)2] with the α-subunit of the NHase. The incorporation of cobalt into the NHase of P. putida was confirmed to be dependent on the α-subunit substitution between the cobalt-containing α(StrepP14K)2 and the cobalt-free NHase. Cobalt was inserted into cobalt-free α(StrepP14K)2 but not into cobalt-free NHase, suggesting that P14K functions not only as a self-subunit swapping chaperone but also as a metallochaperone. In addition, NHase from P. putida was also expressed by a mutant gene that was designed with a order. Our findings expand the general features of self-subunit swapping maturation. PMID:23226397

  4. Mössbauer effect studies and X-ray diffraction analysis of cobalt ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Cobalt ferrite (CoxFe3–xO4) is prepared in powder form by thermal decomposition of iron and cobalt salts and is analysed by X-ray diffraction and Mössbauer spectroscopic techniques. The variation of. Mössbauer parameters, lattice parameters and crystallite size of the products formed with variation in the.

  5. A Rapid Synthetic Method for the Preparation of Two Tris-Cobalt(III) Compounds.

    Science.gov (United States)

    Jackman, Donald C.; Rillema, D. Paul

    1989-01-01

    Reports a method of preparation for tris(ethylenediamine)cobalt(III) and tris(2,2'-bipyridine)cobalt(III) that will shorten the preparation time by approximately 3 hours. Notes the time for synthesis and isolation of compound one was 1 hour (yield 38 percent) while compound two took 50 minutes (yield 71%). (MVL)

  6. Understanding the roles of the strategic element cobalt in nickel base superalloys

    Science.gov (United States)

    Stephens, J. R.; Dreshfield, R. L.

    1983-01-01

    The United States imports over 90% of its cobalt, chromium, columbium, and tantalum, all key elements in high temperature nickel base superalloys for aircraft gas turbine disks and airfoils. Research progress in understanding the roles of cobalt and some possible substitutes effects on microstructure, mechanical properties, and environmental resistance of turbine alloys is discussed.

  7. Effects of Cobalt on Structure, Microchemistry and Properties of a Wrought Nickel-Base Superalloy

    Science.gov (United States)

    Jarrett, Robert N.; Tien, John K.

    1982-06-01

    Cobalt in a 17 pct cobalt containing wrought nickel-base superalloy is systematically substituted for by nickel in order to determine the role of cobalt. The eventual goal is to reduce the levels of cobalt, a critical strategic element, in superalloys. It is found that the strengthening γ microstructure is highly heat treatment sensitive. Reducing cobalt did not result in a reduction of the fine γ precipitates after a coarse grain type (blading) heat treatment, but did after a fine grain type (disk) heat treatment. Representative mechanical properties were determined for each case to isolate microstructural and microchemistry effects. Ambient yield strength and tensile strength were seen to decrease by no more than 15 pct and 7 pct, respectively, even when all the cobalt was removed. The decrease in strength is quantitatively discussed and shown to be consistent with the observed microstructural results and microchemistry results obtained using STEM/EDS. Elevated temperature creep and stress rupture resistances were concluded to be affected by alloy cobalt content through its effect on strengthening γ volume fraction. Significant decreases in these properties were observed for the lower cobalt content alloys. Long term aging, precipitate coarsening, and carbide stability results are also presented and discussed.

  8. Cobalt supported on carbon nanofibers as catalysts for the Fischer-Tropsch synthesis

    NARCIS (Netherlands)

    Bezemer, G.L.

    2006-01-01

    The Fischer-Tropsch (FT) process converts synthesis gas (H2/CO) over a heterogeneous catalyst into hydrocarbons. Generally, cobalt catalysts supported on oxidic carriers are used for the FT process, however it appears to be difficult to obtain and maintain fully reduced cobalt particles. To overcome

  9. The Application of Moessbauer Emission Spectroscopy to Industrial Cobalt Based Fischer-Tropsch Catalysts

    International Nuclear Information System (INIS)

    Loosdrecht, J. van de; Berge, P. J. van; Craje, M. W. J.; Kraan, A. M. van der

    2002-01-01

    The application of Moessbauer emission spectroscopy to study cobalt based Fischer-Tropsch catalysts for the gas-to-liquids process was investigated. It was shown that Moessbauer emission spectroscopy could be used to study the oxidation of cobalt as a deactivation mechanism of high loading cobalt based Fischer-Tropsch catalysts. Oxidation was observed under conditions that are in contradiction with the bulk cobalt phase thermodynamics. This can be explained by oxidation of small cobalt crystallites or by surface oxidation. The formation of re-reducible Co 3+ species was observed as well as the formation of irreducible Co 3+ and Co 2+ species that interact strongly with the alumina support. The formation of the different cobalt species depends on the oxidation conditions. Iron was used as a probe nuclide to investigate the cobalt catalyst preparation procedure. A high-pressure Moessbauer emission spectroscopy cell was designed and constructed, which creates the opportunity to study cobalt based Fischer-Tropsch catalysts under realistic synthesis conditions.

  10. Influence of DC arc current on the formation of cobalt-based ...

    Indian Academy of Sciences (India)

    Nanostructures; magnetism; thermal plasma; cobalt nanostructures. Abstract. The synthesis of cobalt-based magnetic nanostructures using DC arc discharge technique with varying arc current is reported here. The structural ... Also change in arc current leads to variationin phase, diversity in morphology etc. Other property ...

  11. Nickel cobalt oxide hollow nanosponges as advanced electrocatalysts for the oxygen evolution reaction

    OpenAIRE

    Zhu, Chengzhou; Wen, Dan; Leubner, Susanne; Oschatz, Martin; Liu, Wei; Holzschuh, Matthias; Simón, Frank M.; Kaskel, Stefan; Eychmüller, Alexander

    2015-01-01

    A class of novel nickel cobalt oxide hollow nanosponges were synthesized through a sodium borohydride reduction strategy. Due to their porous and hollow nanostructures, and synergetic effects between their components, the optimized nickel cobalt oxide nanosponges exhibited excellent catalytic activity towards oxygen evolution reaction.

  12. Interface Controlled Oxidation States in Layered Cobalt Oxide Nanoislands on Gold

    DEFF Research Database (Denmark)

    Walton, Alexander; Fester, Jakob; Bajdich, Michal

    2015-01-01

    Layered cobalt oxides have been shown to be highly active catalysts for the oxygen evolution reaction (OER; half of the catalytic “water splitting” reaction), particularly when promoted with gold. However, the surface chemistry of cobalt oxides and in particular the nature of the synergistic effect...

  13. Directed magnetic field induced assembly of high magnetic moment cobalt nanowires

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A directed magnetic field induced assembly technique was employed to align two phase (h.c.p. + f.c.c.) cobalt nanoparticles in a mechanically robust long wire morphology. Co nanoparticles with an average size of 4.3 nm and saturation magnetization comparable to bulk cobalt were synthesized...

  14. Effect of long-term cobalt deprivation on methanol degradation in a methanogenic granular sludge bioreactor

    NARCIS (Netherlands)

    Zandvoort, M.H.; Geerts, R.; Lettinga, G.; Lens, P.N.L.

    2002-01-01

    The effect of the trace metal cobalt on the conversion of methanol in an upflow anaerobic sludge bed (UASB) reactor was investigated by studying the effect of cobalt deprivation from the influent on the reactor efficiency and the sludge characteristics. A UASB reactor (30 C; pH 7) was operated for

  15. The cobalt spot test - further insights into its performance and use

    DEFF Research Database (Denmark)

    Midander, Klara; Julander, Anneli; Skare, Lizbet

    2013-01-01

    A spot test was recently developed for easy and rapid testing to detect whether cobalt is available on surfaces in contact with skin.......A spot test was recently developed for easy and rapid testing to detect whether cobalt is available on surfaces in contact with skin....

  16. Crystalline niobia with tailored porosity as support for cobalt catalysts for the Fischer–Tropsch synthesis

    NARCIS (Netherlands)

    Hernández Mejía, C.; den Otter, J. H.; Weber, J. L.; de Jong, K. P.

    2017-01-01

    Structure and catalytic performance of niobia-supported cobalt catalysts were studied based on crystal phase, porosity and cobalt loading. Crystalline niobia as support proved to be a prerequisite to obtain highly active and selective Co/niobia Fischer–Tropsch catalysts, whereas amorphous niobia

  17. Design electronic of manual control for cobalt unit Alcyon II of the National Center of Radiotherapy

    International Nuclear Information System (INIS)

    Morraz V, E.; Campos, X.

    2002-01-01

    A manual control for the cobalt unit, of French production, it was designed by the team of electronic of the national center of radiotherapy with materials found in the national trade. The control has the same characteristics that the original one and it is also adapted a switch from which you can control the lights of the room of the cobalt

  18. Speciation analysis of cobalt in foods by high-performance liquid chromatography and neutron activation analysis

    International Nuclear Information System (INIS)

    Muto, Toshio; Koyama, Motoko

    1994-01-01

    A combined method by coupling high-performance liquid chromatography (HPLC, as a separation method) with neutron activation analysis (as a detection method) have been applied to the speciation analysis of cobalt in daily foods (e.g. egg, fish and milk). Cobalt species including free cobalt, vitamin B 12 and protein-bound cobalt were separated with a preparative HPLC and a centrifuge. Subsequently, the determination of cobalt in the separated species was made by neutron activation analysis. The results showed that the content of the total cobalt in the foods was found to lie in the range 0.4-11ng/g(0.4-11ppb) based on wet weight. The compositions of free cobalt, vitamin B 12 and protein-bound cobalt were ranged 16-43%, 55-73%, 2.3-17%, respectively. These experimental evidences suggest that the combination of HPLC and neutron activation analysis is expected to be a useful tool for speciation analysis of trace elements in biological as well as environmental materials. (author)

  19. Cobalt particle size effects on catalytic performance for ethanol steam reforming – Smaller is better

    NARCIS (Netherlands)

    Silva, da A.L.M.; Breejen, den J.P.; Mattos, L.V.; Bitter, J.H.; Jong, de K.P.; Noronha, F.B.

    2014-01-01

    The effect of the cobalt particle size in the ethanol steam reforming reaction at 773 K for hydrogen production was investigated using cobalt on carbon nanofiber catalysts. It was found that the turnover frequency increases with decreasing Co particle size, which was attributed to the increasing

  20. Cobalt particle size effects on catalytic performance for ethanol steam reforming - Smaller is better

    NARCIS (Netherlands)

    Da Silva, Andre L M; Den Breejen, Johan P.; Mattos, Lisiane V.; Bitter, Johannes H.; De Jong, Krijn P.; Noronha, Fábio B.

    2014-01-01

    The effect of the cobalt particle size in the ethanol steam reforming reaction at 773 K for hydrogen production was investigated using cobalt on carbon nanofiber catalysts. It was found that the turnover frequency increases with decreasing Co particle size, which was attributed to the increasing

  1. New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus

    2002-01-01

    Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia......Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia...

  2. Heavy metals in foodstuffs. Pt. 5. Cobalt content of raw cacao and finished cacao products

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, G.

    1987-01-01

    By means of the graphite-tube oven technique we determined cobalt contents in raw cacao and in some finished cacao products. The cobalt content increases with an increasing percentage of cacao in the product; a decisive factor is where the cacao utilized comes from.

  3. Effet des sels de métaux lourds (chlorure de Cobalt et chlorure de ...

    African Journals Online (AJOL)

    These effects are characterized by damage to the plasma membrane, more pronounced in the case of mercuric chloride than the cobalt chloride. This study will contribute to ameliorate the treatment during the contamination of heavy metal such as cobalt and mercuric chlorides. Keywords: hepatocytes, Phospholipids ...

  4. Effect of occupational exposure to cobalt blue dyes on the thyroid volume and function of female plate painters

    DEFF Research Database (Denmark)

    Prescott, E; Netterstrøm, B; Faber, J

    1992-01-01

    It has previously been shown that long-term oral exposure to cobalt can cause goiter and myxedema. The effect of industrial cobalt exposure on thyroid volume and function was determined for 61 female plate painters exposed to cobalt blue dyes in two Danish porcelain factories and 48 unexposed ref...

  5. Stimulation of Methanol Degradation in UASB Reactors: In Situ Versus Pre-Loading Cobalt on Anaerobic Granular Sludge

    NARCIS (Netherlands)

    Zandvoort, M.H.; Gieteling, J.; Lettinga, G.; Lens, P.N.L.

    2004-01-01

    The effect of pre-loading and in situ loading of cobalt onto a cobalt-limited granular sludge on the performance of methanol fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was inoculated with cobalt pre-loaded sludge (24h; 30degreesC; 1 mM CoCl2) and a second UASB

  6. University of Tennessee Comparative Animal Research Laboratory accident in 1971

    International Nuclear Information System (INIS)

    Vodopick, H.; Andrews, G.A.

    1980-01-01

    On 4 February 1971, a 32-year-old research technologist performing seed irradiated experiments at the University of Tennessee Comparative Animal Research Laboratory was exposed to a Cobalt 60 source of 7700 curies for 40 seconds. Details of the accident, dose estimates from dosimetry studies, and acute biological clinical findings are discussed. Follow-up clinical data on the hematopoietic system, biochemistry, fingers, and blood counts are discussed

  7. Tailoring the oxidation state of cobalt through halide functionality in sol-gel silica

    Science.gov (United States)

    Olguin, Gianni; Yacou, Christelle; Smart, Simon; Diniz da Costa, João C.

    2013-01-01

    The functionality or oxidation state of cobalt within a silica matrix can be tailored through the use of cationic surfactants and their halide counter ions during the sol-gel synthesis. Simply by adding surfactant we could significantly increase the amount of cobalt existing as Co3O4 within the silica from 44% to 77%, without varying the cobalt precursor concentration. However, once the surfactant to cobalt ratio exceeded 1, further addition resulted in an inhibitory mechanism whereby the altered pyrolysis of the surfactant decreased Co3O4 production. These findings have significant implications for the production of cobalt/silica composites where maximizing the functional Co3O4 phase remains the goal for a broad range of catalytic, sensing and materials applications. PMID:24022785

  8. Consequence of cobalt on structural, optical and dielectric properties in ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zia, Amir, E-mail: amirziaphysics@hotmail.com [Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad (Pakistan); Ahmed, S. [Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad (Pakistan); Advanced Electronics Laboratory, International Islamic University, Islamabad (Pakistan); Shah, N.A.; Anis-ur-Rehman, M. [COMSATS, Institute of Information Technology, Islamabad (Pakistan); Khan, E.U. [Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad (Pakistan); Basit, M. [Centre for Solid State Physics, Punjab University (Pakistan)

    2015-09-15

    The critical role of cobalt dopant in ZnO nanostructures with different cobalt concentrations has been explored on the basis of structural, optical and dielectric mechanisms. X-ray diffraction (XRD) analysis shows that the Co{sup +2} ions replace Zn{sup +2} ions in the ZnO matrix, producing lattice strain. Diffused Reflectance Spectroscopy (DRS) shows a red shift in optical energy band gap with increase in cobalt content, along with the presence of transitions in high spin states due to tetrahedrally coordinated cobalt ions. The dielectric characterization explains the disparity in dynamic dielectric parameters like capacitance, dielectric constant, tangent loss, AC conductivity and impedance as a function of frequency. Capacitance and both static and dynamic dielectric constants found to be decreasing with cobalt addition. The anomaly in these pronounced parameters can address the key problems of the material at higher frequencies device operation.

  9. Effects of cobalt on the microstructure of Udimet 700. M.S. Thesis Final Report

    Science.gov (United States)

    Engel, M. A.

    1982-01-01

    Cobalt, a critical and "strategic" alloying element in many superalloys, was systematically substituted by nickel in experimental alloys Udimet 700 containing 0.1, 4.3, 8.6, 12.8 and the standard 17.0 wt.% cobalt. Electrolytic and chemical extraction techniques, X-ray diffraction, scanning electron and optical microscopy were used for the microstructural studies. The total weight fraction of gamma' was not significantly affected by the cobalt content, although a difference in the size and quantities of the primary and secondary gamma' phases was apparent. The lattice parameters of the gamma' were found to increase with increasing cobalt content while the lattice mismatch between the gamma matrix and gamma' phases decreased. Other significant effects of cobalt on the weight fraction, distribution and formation of the carbide and boride phases as well as the relative stability of the experimental alloys during long-time aging are also discussed.

  10. Fabrication and analysis of ordered magnetic cobalt nanoparticles; Herstellung und Untersuchung geordneter magnetischer Kobaltnanoteilchen

    Energy Technology Data Exchange (ETDEWEB)

    Zuern, Klaus P.

    2009-12-17

    In the dissertation on hand monodisperse, wellordered magnetic cobalt and cobalt hydride nanoparticles have been produced and investigated magnetically. The preparation was achieved by diblock-copolymer-micelles filled with cobalt salt, from which nanoparticles of elementary cobalt respectively cobalt hydride were generated in different steps of the procedure. It was evident that the cobalthydride generated by the hydrogen plasma was surprisingly stable. It could even be taken into consideration as a hydrogen storage device for fuel cell. The magnetic properties of the particles has been investigated by x-ray magnetic circular dichroism (XMCD). In addition it was evident, that it was principally impossible to investigate a film layered on a substrate with a SQUID-magnetometer, if this film produces only a small signal as well absolutely as relatively to the magnetically measured total moment of the sample. (orig.)

  11. Adsorption isotherms for cesium ions in seawater of insoluble cobalt and nickel ferrocyanide-impregnated fibers

    International Nuclear Information System (INIS)

    Amakai, Wataru; Sugiyama, Mai; Fujiwara, Kunio; Umeno, Daisuke; Saito, Kyoichi; Sugo, Takanobu

    2014-01-01

    Cobalt or nickel ferrocyanide was impregnated into an anion-exchange polymer chain grafted onto a commercially available 6-nylon fiber. First, ferrocyanide ions (Fe(CN) 6 4- ) were bound to the anion-exchange fiber. Second, the fiber was made to reach with cobalt or nickel ions to form insoluble cobalt or nickel ferrocyanide via precipitation. For comparison, a commercially available anion-exchange bead was used as a support for the impregnation of insoluble cobalt or nickel ferrocyanide. The contents of metal ferrocyanides impregnated onto the fiber were approximately half those impregnated onto the bead. Adsorption isotherms of insoluble cobalt or nickel ferro-cyanide-impregnated fiber and bead for cesium ions in seawater correlated well with a Langmuir-type isotherm. The saturation capacity for cesium ions in seawater per gram of insoluble metal ferrocyanides was almost identical between the fiber and the bead. (author)

  12. Facile fabrication of cobalt oxalate nanostructures with superior specific capacitance and super-long cycling stability

    Science.gov (United States)

    Cheng, Guanhua; Si, Conghui; Zhang, Jie; Wang, Ying; Yang, Wanfeng; Dong, Chaoqun; Zhang, Zhonghua

    2016-04-01

    Transition metal oxalate materials have shown huge competitive advantages for applications in supercapacitors. Herein, nanostructured cobalt oxalate supported on cobalt foils has been facilely fabricated by anodization, and could directly serve as additive/binder-free electrodes for supercapacitors. The as-prepared cobalt oxalate electrodes present superior specific capacitance of 1269 F g-1 at the current density of 6 A g-1 in the galvanostatic charge/discharge test. Moreover, the retained capacitance is as high as 87.2% as the current density increases from 6 A g-1 to 30 A g-1. More importantly, the specific capacitance of cobalt oxalate retains 91.9% even after super-long cycling of 100,000 cycles. In addition, an asymmetric supercapacitor assembled with cobalt oxalate (positive electrode) and activated carbon (negative electrode) demonstrates excellent capacitive performance with high energy density and power density.

  13. Cycle life and utilization studies on cobalt microencapsulated AB 5 type metal hydride

    Science.gov (United States)

    Durairajan, Anand; Haran, Bala S.; Popov, Branko N.; White, Ralph E.

    LaNi 4.27Sn 0.24 alloy was microencapsulated with cobalt by electroless deposition. The coated material has a higher capacity compared to the bare alloy due to the faradaic reaction of cobalt during discharge. This additional capacity has been studied using various material and electrochemical characterization techniques. The capacity due to cobalt varies depending on the amount of active material available for reaction. An increase in utilization is seen with decrease in thickness of the coating. Active surface area and the transport process within the film control the amount of cobalt utilized. Finally, cobalt coated alloys are seen to cycle ten times more than bare LaNi 4.24Sn 0.27 with constant capacity.

  14. Pennsylvania State University Breazeale Nuclear Reactor. Thirtieth annual progress report, July 1, 1984-June 30, 1985

    International Nuclear Information System (INIS)

    Levine, S.H.; Totenbier, R.E.

    1985-08-01

    This report is the thirtieth annual progress report of the Pennsylvania State University Breazeale Nuclear Reactor and covers such topics as: personnel; reactor facility; cobalt-60 facility; education and training; Radionuclear Application Laboratory; Low Level Radiation Monitoring Laboratory; and facility research utilization

  15. The effect of cobalt substitution on magnetic hardening of magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Mozaffari, M., E-mail: mozafari@sci.ui.ac.ir [Department of Physics, Faculty of Science, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Hadadian, Y. [Physics Department, Razi University, Taghebostan, Kermanshah (Iran, Islamic Republic of); Aftabi, A. [Department of Physics, University of Kurdistan, Sanandaj 66177-15175 (Iran, Islamic Republic of); Oveisy Moakhar, M. [Physics Department, Razi University, Taghebostan, Kermanshah (Iran, Islamic Republic of)

    2014-03-15

    In this work cobalt-substituted magnetite (Co{sub x}Fe{sub 1−x}Fe{sub 2}O{sub 4}, x=0, 0.25, 0.50 and 0.75) nanoparticles were synthesized by coprecipitation method and their structural and magnetic properties were investigated. X-ray diffraction was carried out and the results show that all of the samples have single phase spinel structure. Microstructure of the samples was studied using a field emission scanning electron microscope and the results show that particle sizes of the prepared nanoparticles were uniform and in the 50–55 nm range. Room temperature magnetic properties of the nanoparticles were measured by an alternating gradient force magnetometer and the results revealed that substituting cobalt for iron in magnetite structure, changes the magnetite from a soft magnetic material to a hard one. So that coercivity changes from 0 (a superparamagnetic state) to 337 Oe (a hard magnetic material), which is a remarkable change. Curie temperatures of the samples were determined by recording their susceptibility-temperature (χ–T) curves and the results show that by increasing cobalt content, Curie temperature of the samples also increases. Also χ–T curves of the samples were recorded from above Curie temperature to room temperature (first cooling), while the curves in the second heating and second cooling have the same behaviour as the first cooling curve. The results depict that all samples have different behaviour in the first cooling and in the first heating processes. This shows remarkable changes of the cation distribution in the course of first heating. - Highlights: • It is possible to get Co substituted magnetite nanoparticles by coprecipitation method. • Prepared nanoparticles have different cation distribution in comparison with that of bulk counterparts. • Co substitution increases coercivity of the magnetite.

  16. Nanotoxicity of gold and gold-cobalt nanoalloy.

    Science.gov (United States)

    Girgis, E; Khalil, W K B; Emam, A N; Mohamed, M B; Rao, K V

    2012-05-21

    Nanotoxicology test of gold nanoparticles (Au NPs) and gold-cobalt (Au-Co) nanoalloy is an important step in their safety evaluation for biomedical applications. The Au and Au-Co NPs were prepared by reducing the metal ions using sodium borohydride (NaBH(4)) in the presence of polyvinyl pyrrolidone (PVP) as a capping material. The average size and shape of the nanoparticles (NPs) were characterized using high resolution transmission electron microscopy (HRTEM). Cobalt presence in the nanoalloy was confirmed by energy dispersive X-ray spectroscopy (EDX) analysis, and the magnetic properties of these particles were determined using a vibrating sample magnetometer (VSM). The Gold and gold-cobalt NPs of average size 15 ± 1.5 nm were administered orally to mice with a dose of 80, 160, and 320 mg/kg per body weight (bw) using gavages. Samples were collected after 7 and 14 days of the treatment. The results indicated that the Au-Co NPs were able to induce significant alteration in the tumor-initiating genes associated with an increase of micronuclei (MNs) formation and generation of DNA adduct (8-hydroxy-2-deoxyguanosine, 8-OHdG) as well as a reduction in the glutathione peroxidase activity. This action of Au-Co NPs was observed using 160 and 320 mg/kg bw at both time intervals. However, Au NPs had much lower effects than Au-Co NPs on alteration in the tumor-initiating genes, frequency of MNs, and generation of 8-OHdG as well as glutathione peroxidase activity except with the highest dose of Au NPs. This study suggests that the potential to cause in vivo genetic and antioxidant enzyme alterations due to the treatment by Au-Co nanoalloy may be attributed to the increase in oxidative stress in mice.

  17. Morphological and magnetic properties of cobalt nanoclusters electrodeposited onto HOPG

    International Nuclear Information System (INIS)

    Rivera, M.; Rios-Reyes, C.H.; Mendoza-Huizar, L.H.

    2008-01-01

    In this work, the morphological and magnetic properties of cobalt nanoclusters obtained from two different sulphate electrolyte solutions were studied. The aggregates were electrodeposited onto highly oriented pyrolytic graphite electrodes in overpotential conditions, in order to investigate the cationic influence on the final properties of the aggregates. In both cases, scanning electron microscopy and atomic force microscopy showed random isolated clusters on the electrode surface, where size variations were determined by the electrolyte solution. By using magnetic force microscopy, the distribution of the electrodeposited magnetic material was more clearly observed which gave some insights on the growth mechanism of these aggregates.

  18. Coordination compounds of cobalt and cadmium with isobutyric acid amide

    International Nuclear Information System (INIS)

    Tsivadze, A.Yu.; Ivanova, I.S.; Solovkina, O.A.

    1983-01-01

    Coordination compounds of cobalt and cadmium with isobutyric acid amide (IBAA) of Co(NCS) 2 x(IBAA) 2 (H 2 O) 2 , CoCl 2 (IBAA) 4 , CoI 2 (IBAA) 8 (H 2 O) 2 , CdI 2 (IBAA) 2 composition have been synthesized and characterized. Their infrared absorption spectra (200-400 cm -1 ), electron reflection spectra (200-750 nm) were studied. It is shown that in all compounds there are IBAA molecUles coordinated through an oxygen atom. Thiocyanogroups are coordinated throUgh nitrogen atoms

  19. Carbon Nanomaterials from Carbon Monoxide Using Nickel and Cobalt Catalysts

    International Nuclear Information System (INIS)

    Liszka, B.; Krzton, A.; Pawlyta, M.

    2010-01-01

    Two catalysts, nickel and cobalt, supported on MgO were used for carbon nanomaterials deposition by CO disproportionation. The syntheses were performed at 795 and 900 K in the hydrogen atmosphere. The resulting products were investigated using atomic force microscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. Although in the literature carbon nanofibres are expected to form: in the hydrogen presence, we obtained carbon nanotubes, which were multiwall and twisted with the outer diameter of 10-120 nm and the tube length up to 10 μm. (authors)

  20. The development of cobalt-base alloy ball bearing

    International Nuclear Information System (INIS)

    Yu Xinshui; Chen Jianting; Wang Zaishu; Wang Ximei; Huang Chongming.

    1986-01-01

    The main technologies and experiences in developing a Cobalt-base alloy ball bearing are described. In the hardfacing of bearing races, a lower-hardness alloy of type St-6 is used rather than an alloy with hardness similar to that of the ball and finally the hardness of race is increased to match that of the ball by heat treatment. This improvement has certain advantages. The experience of whole developing technology indicates that strict control of the technology in the bearing-race hardfacing is the key problem in the quality assurance of bearings

  1. [Synthesis and spectral properties of tailed sercine tetraphenylporphyrin cobalt complex].

    Science.gov (United States)

    Ni, Chun-lin; Zhou, Chun-qiong; Zhou, Yu; He, Zhi-ke; Yuan, Liang-jie

    2004-04-01

    A new tailed sercine tetraphenylporphinatozinc, 5-(p-butoxyphenyl-10,15,20-trichlorophenyl)porphine and cobalt complex (Co[Ser-TPP]) was synthesized and characterized by elementary analysis, UV, IR, 1HNMR and Raman spectra. The electronic absorption spectra of axial coordination reactions of Co[Ser-TPP] with pyridine, 4-methylpyridine, 4-aminopyridine, 4,4-bipyridine, imidazole, 1-methylimidazole and 2-methylimidazole were inverstigated. The results showed that the changes of electronic absorption spectra of Co[Ser-TPP] could be attributed to the axial coordination reactions of Co[Ser-TPP] with pyridine and imidazole series.

  2. Synthesis and microwave absorbing properties of Cobalt ferrite

    Science.gov (United States)

    Liu, H. Y.; Li, Y. S.

    2018-01-01

    Cobalt ferrite power CoFe2O4 was synthesized through the chemical co-precipitation method. The structure, morphology and microwave absorbing properties were studied by changing raw materials, annealing temperature and experimental steps. The measurements of X-ray diffraction and scanning electron micrograph suggest that annealed CoFe2O4 sample is still a spinel structure. Moreover, the crystalline and grain sizes become large with the enhancement of annealing temperature. The measurements of microwave absorbing properties show that the reflection loss decreases continuously, and the wavelength of maximum absorption loss shift to short-wave limit as the sample thickness increases.

  3. Functionalization of atomic cobalt clusters obtained by electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Cobo, Eldara [Laboratorio de Magnetismo y Tecnologia, Instituto Tecnoloxico, Pabillon de Servicios, Campus Sur, 15782 Santiago de Compostela (Spain); Departamento de Quimica Organica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Rivas Rey, Jose; Blanco Varela, M. Carmen; Lopez Quintela, M. Arturo [Laboratorio de Magnetismo y Tecnologia, Instituto Tecnoloxico, Pabillon de Servicios, Campus Sur, 15782 Santiago de Compostela (Spain); Mourino Mosquera, Antonio; Torneiro Abuin, Mercedes [Departamento de Quimica Organica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela (Spain)

    2006-05-15

    Functionalization of magnetic nanoparticles with appropriate organic molecules is very important for many applications. In the present study, cobalt nanoparticles, with an average diameter of 2 nm corresponding to Co{sub 309} clusters were synthesised by an electrochemical method, and then coated with ADCB (4-(9-deceniloxi)benzoic acid), in order to protect the clusters against oxidation and to obtain a final nanostructure, which can be attached later on to many different materials, like drugs, proteins or some other biological molecules. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Oxygen content determination in perovskite-type cobaltates

    International Nuclear Information System (INIS)

    Conder, K.; Pomjakushina, E.; Soldatov, A.; Mitberg, E.

    2005-01-01

    Three oxygen content determination methods (iodometric titration, gas volumetric analysis and thermogravimetric hydrogen reduction) have been evaluated for the case of rare earth cobaltates LnBCo 2 O 5+δ (were Ln-rare earth, B-alkali earth elements). All the methods are based on oxidation properties of both Co 4+ and Co 3+ cations but different instrumentation was used for each of the method. We have obtained good agreement within ±0.02 in δ for both the iodometric titration and the gas volumetric analysis, whereas the thermogravimetric hydrogen reduction was found to be less credible

  5. Thermal Plasma Decomposition Of Nickel And Cobalt Compounds

    Directory of Open Access Journals (Sweden)

    Woch M.

    2015-06-01

    Full Text Available The paper presents the study on manufacturing of nickel and cobalt powders by thermal plasma decomposition of the carbonates of these metals. It was shown the dependence of process parameters and grain size of initial powder on the composition of final product which was ether metal powder, collected in the container as well as the nanopowder with crystallite size of 70 - 90 nm, collected on the inner wall of the reaction chamber. The occurrence of metal oxides in the final products was confirmed and discussed.

  6. Combustion synthesis of cobalt pigments: Blue and pink

    OpenAIRE

    Mimani, T; Ghosh, Samrat

    2000-01-01

    Idiochromatic blue cobalt aluminate (CoAl2O4) and purple pyroborate Co2B2O5 were prepared by solution combustion method using corresponding metal nitrates, boric acid and carbohydrazide mixtures. Allochromatic Co2+ doped in Al2O3/ZnAl2O4 and Mg2B2O5 pigments having the same colour intensity as idiochromatic pigments were obtained similarly. All the pigments are voluminous, homogeneously coloured with a large surface area. The products are characterized by their characteristic colours, XRD, IR...

  7. Preliminary results about Electrodeposition of Cobalt at laboratory level

    International Nuclear Information System (INIS)

    Cornejo, N.

    1992-01-01

    As of an organic compound, an extraction and Cobalt electrodeposition method had been developed as a part of fabrication aim of a sealed radioactive source with objective to the construction of density meter prototype. It was performed preliminary test of electrodeposition in the laboratory level in a simple cell. The used electrolyte had been a sulphate solution obtained by extraction of an organic solution. It is obtained a Co film by electrodeposition at 55 o C temperature and with an approximately Co concentration in 70 g/lt. (Author) 3 refs., 1 fig., 1 tab

  8. TECHNOLOGY DEVELOPMENT FOR IRON AND COBALT FISCHER-TROPSCH CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Burtron H. Davis

    1999-01-30

    The effects of copper on Fischer-Tropsch activity, selectivity and water-gas shift activity were studied over a wide range of syngas conversion. Three catalyst compositions were prepared for this study: (a) 100Fe/4.6Si/1.4K, (b) 100Fe/4.6Si/0.10Cu/1.4K and (c) 100Fe/4.6Si/2.0Cu/1.4K. The results are reported in Task 2. The literature review for cobalt catalysts is approximately 90% complete. Due to the size of the document, it has been submitted as a separate report labeled Task 6.

  9. Application of ferro-cobalt magnetic fluid for oil sealing

    International Nuclear Information System (INIS)

    Kim, Y.S.; Kim, Y.H.

    2003-01-01

    Ferro-cobalt magnetic powder in nano-meter size is manufactured to implement in a magnetic fluid sealing mechanism. The powder is coated with silicon dioxide for the prevention of aggregation. Also three surface active agents are applied to improve particle dispersion in fluid medium. The average size of the powder particle is 9.4 nm, and its magnetization is 154 emu/g in the magnetic field of 10 kOe. The dispersed particle shows little settlement for 20 weeks. From the sealing performance test, the holding pressure is 25 times as high as that of a conventional magnetite sealing

  10. Substitution of cobalt alloying in PWR primary circuit gate valves

    International Nuclear Information System (INIS)

    Cachon, L.; Sudreau, F.; Brunel, L.

    1995-01-01

    The object of this study is qualify cobalt-free alternative alloys for valve applications. This paper focus on tribological characterization of numerous coatings is done by using the first one, of a classical type. Then tests are performed with the second one which simulates solicitations supported by gate valves in primary circuit of PWR. 35% Ni-Cr - 65% Cr 3 C 2 coating, deposited by detonation gun technology, gives us hope to find a substitute of Stelite 6. (author). 5 refs., 16 figs., 2 tabs

  11. Economics of gamma processing in cobalt-60 irradiation facilities

    International Nuclear Information System (INIS)

    Gay, H. G.; Kotler, J. G.

    1985-01-01

    Gamma processing by cobalt-60 is well established. However, since irradiation of food is relatively new from the commercial point of view, it is important to assess costs of gamma irradiation in the context of food processing. Five different types of AECL-RCC irradiation equipment are examined in terms of their throughputs, and capital and operating costs. Using these figures, costs of irradiation of nine types of food products are presented. In general, these represent about 2-10% of the wholesale cost of these products

  12. Pharmacokinetics and selected pharmacodynamics of cobalt following a single intravenous administration to horses.

    Science.gov (United States)

    Knych, H K; Arthur, R M; Mitchell, M M; Holser, I; Poppenga, R; Smith, L L; Helm, M N; Sams, R A; Gaskill, C L

    2015-07-01

    Cobalt has been used by human athletes due to its purported performance-enhancing effects. It has been suggested that cobalt administration results in enhanced erythropoiesis, secondary to increased circulating erythropoietin (EPO) concentrations leading to improvements in athletic performance. Anecdotal reports of illicit administration of cobalt to horses for its suspected performance enhancing effects have led us to investigate the pharmacokinetics and pharmacodynamic effects of this compound when administered in horses, so as to better regulate its use. In the current study, 18 horses were administered a single intravenous dose of cobalt chloride or cobalt gluconate and serum and urine samples collected for up to 10 days post administration. Cobalt concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS) and pharmacokinetic parameters determined. Additional blood samples were collected for measurement of equine EPO concentrations as well as to assess any effects on red blood cell parameters. Horses were observed for adverse effects and heart rate monitored for the first 4 h post administration. Cobalt was characterized by a large volume of distribution (0.939 L/kg) and a prolonged gamma half-life (156.4 h). Cobalt serum concentrations were still above baseline values at 10 days post administration. A single administration of cobalt had no effect on EPO concentrations, red blood cell parameters or heart rate in any of the horses studied and no adverse effects were noted. Based on the prolonged gamma half-life and prolonged residence time, regulators should be able to detect administration of a single dose of cobalt to horses. Copyright © 2014 John Wiley & Sons, Ltd.

  13. Comparative electrochemical study of some cobalt(III and cobalt(II complexes with azamacrocycles and b-diketonato ligands

    Directory of Open Access Journals (Sweden)

    K. BABIC-SAMARDZIJA

    2003-12-01

    Full Text Available The electrochemical properties of eight mixed-ligand cobalt(III and cobalt(II complexes of the general formulas [CoIII(Raccyclam](ClO42 (1–(4 and [Co2II(Ractpmc](ClO43 (5–(8 were studied. The substances were investigated in aqueous NaClO4 solution and non-aqueous LiClO4/CH3CN solution by cyclic voltammetry at a glassy carbon electrode. In aqueous solution, cyclam and Rac ligands being soluble in water undergo anodic oxidation. Coordination to Co(III in complexes 1–4, stabilizes these ligands but reversible peaks in catohodic region indicate the redox reaction CoIII/CoII ion. In the case of the binuclear Co(II complexes 5–8, peaks recorded on the CVs represent oxidation of the bridged Rac ligand. The complexes examined influence the cathodic reaction of hydrogen evolution in aqueous solutions by shifting its potential to more negative values and its current is increased. In non-aqueous solution the CVs of the ligands show irreversible anodic peaks for cyclam, tpmc and for the Rac ligands soluble in acetonitrile. The absence of any peaks in the case of the investigated complexes 1–4 indicates that coordination to Co(III stabilizes both the cyclam and Rac ligands. Cyclic voltammograms of the complexes 5–8 show oxidation processes of the Rac ligand and Co(II ions but the absence of a highly anodic peak of the coordinated macrocycle tpmc shows its stabilization. Contrary to in aqueous solution, the redox reaction Co(III/Co(II does not occur in acetonitrate indicating a higher stability of the complexes 1–4 in this media in comparison with the binuclear cobalt(II-tpmc complexes 5–8.

  14. Electrowinning of cobalt from sulfate-chloride and sulfate solutions of cobalt and manganese under dynamic conditions

    Directory of Open Access Journals (Sweden)

    Л. П. Хоменко

    2017-08-01

    Full Text Available The design of an electrolyzer for electrowinning in dynamic conditions is developed. The dependence of the results of electrowinning of cobalt and manganese from sulfate and sulfate-chloride solutions under dynamic conditions using a titanium cathode and a lead anode with 1 % of silver was studied. It was found that the best extraction results for the current yield and the specific energy consumption were obtained by electrolysis from sulfate solutions at a low concentration of manganese in an electrolyser without a perforated baffle plate separating the cathode and anode spaces.

  15. Nickel, copper and cobalt coalescence in copper cliff converter slag

    Directory of Open Access Journals (Sweden)

    Wolf A.

    2016-01-01

    Full Text Available The aim of this investigation is to assess the effect of various additives on coalescence of nickel, copper and cobalt from slags generated during nickel extraction. The analyzed fluxes were silica and lime while examined reductants were pig iron, ferrosilicon and copper-silicon compound. Slag was settled at the different holding temperatures for various times in conditions that simulated the industrial environment. The newly formed matte and slag were characterized by their chemical composition and morphology. Silica flux generated higher partition coefficients for nickel and copper than the addition of lime. Additives used as reducing agents had higher valuable metal recovery rates and corresponding partition coefficients than fluxes. Microstructural studies showed that slag formed after adding reductants consisted of primarily fayalite, with some minute traces of magnetite as the secondary phase. Addition of 5 wt% of pig iron, ferrosilicon and copper-silicon alloys favored the formation of a metallized matte which increased Cu, Ni and Co recoveries. Addition of copper-silicon alloys with low silicon content was efficient in copper recovery but coalescence of the other metals was low. Slag treated with the ferrosilicon facilitated the highest cobalt recovery while copper-silicon alloys with silicon content above 10 wt% resulted in high coalescence of nickel and copper, 87 % and 72 % respectively.

  16. Cobalt Nanoparticle Inks for Printed High Frequency Applications on Polycarbonate

    Science.gov (United States)

    Nelo, Mikko; Myllymäki, Sami; Juuti, Jari; Uusimäki, Antti; Jantunen, Heli

    2015-12-01

    In this work the high frequency properties of low curing temperature cobalt nanoparticle inks printed on polycarbonate substrates were investigated. The inks consisted of 30-70 vol.% metallic cobalt nanoparticles and poly (methylene methacrylate) polymer, having excellent adhesion on polycarbonate and a curing temperature of 110°C. The influence of binder material content on the electromagnetic properties of the ink was investigated using the shorted microstrip transmission-line perturbation method. Changes in mechanical properties were evaluated with adhesion tests using the pull-out strength test and the ASTM D 3359-B cross-hatch tape peel test. The microstructure of the printed patterns was investigated with field emission scanning electron microscopy (FESEM). The inks remained mechanically durable with metal contents up to 60 vol.%, achieving pull-off strength of up to 5.2 MPa and the highest marks in adhesion of the tape peel test. The inks obtained a relative permeability of 1.5-3 in the 45 MHz-10 GHz band with a magnetic loss tangent of 0.01-0.06. The developed inks can be utilized in various printed electronics applications such as antenna miniaturization, antenna substrates and magnetic sensors or sensing.

  17. Exchange spring like magnetic behavior in cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chithra, M.; Anumol, C.N. [Department of Physics, Central University of Kerala, Riverside Transit Campus, Nileshwar, P.O. Padnekkad, Kasaragod, Kerala 671314 (India); Sahu, Baidyanath [Department of Physics, I.I.T. Bombay, Powai, Mumbai 400076 (India); Sahoo, Subasa C., E-mail: subasa.cs@gmail.com [Department of Physics, Central University of Kerala, Riverside Transit Campus, Nileshwar, P.O. Padnekkad, Kasaragod, Kerala 671314 (India)

    2016-03-01

    Cobalt ferrite nanoparticles were prepared by sol–gel technique and were annealed at 900 °C in air for 2 h. Structural properties were studied by X-ray diffraction, Raman spectroscopy and Fourier transformed infrared spectroscopy. Scanning electron microscopy and transmission electron microscopy studies show presence of mostly two different sizes of grains in these samples. Magnetization value of 58.36 emu/g was observed at 300 K for the as prepared sample and an enhanced magnetization close to the bulk value of 80.59 emu/g was observed for the annealed sample. At 10 K a two stepped hysteresis loop showing exchange spring magnetic behavior was observed accompanied by very high values of coercivity and remanence. Two clear peaks were observed in the derivative of demagnetization curve in the as prepared sample where as two partially overlapped peaks were observed in the annealed sample. The observed magnetic properties can be understood on the basis of the grain size and their distribution leading to the different types of intergranular interactions in these nanoparticles. - Highlights: • Cobalt ferrite nanoparticles were prepared by sol–gel technique and were annealed. • Microscopy studies showed presence of mostly two different sizes of grains. • A two stepped magnetic hysteresis loop was observed in these samples at 10 K. • Two well resolved peaks were observed in the derivative of demagnetization curve. • Grain size and their distribution lead to such two stepped exchange spring behavior.

  18. Self-biased cobalt ferrite nanocomposites for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Hannour, Abdelkrim, E-mail: abdelkrim.hannour@hotmail.com [LT2C Laboratory, Jean-Monnet University, 25 rue Dr. Rémy Annino, F-42000, Saint-Etienne (France); Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches [LT2C Laboratory, Jean-Monnet University, 25 rue Dr. Rémy Annino, F-42000, Saint-Etienne (France); Neveu, Sophie; Dupuis, Vincent [UPMC Univ Paris 06, UMR 7195, PECSA, F-75005, Paris (France)

    2014-03-15

    Oriented CoFe{sub 2}O{sub 4} nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.). - Highlights: • Oriented magnetic CoFe{sub 2}O{sub 4} nanoparticles were fabricated by magnetophoretic deposition of functionalized cobalt ferrite particles into porous alumina membrane. • The nanocomposite obtained presents an out-of-plane easy axis with a large remanent magnetization and coercitivity. • The high effective internal magnetic anisotropy contributes to the permanent bias along the wire axis. • The frequency ferromagnetic resonance ranges from 46.5 to 49.5 GHz, depending on the filling ratio of the membrane. • We have obtained a good agreement between Ansoft High Frequency Structure Simulator simulations and experimental results.

  19. Self-biased cobalt ferrite nanocomposites for microwave applications

    International Nuclear Information System (INIS)

    Hannour, Abdelkrim; Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches; Neveu, Sophie; Dupuis, Vincent

    2014-01-01

    Oriented CoFe 2 O 4 nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.). - Highlights: • Oriented magnetic CoFe 2 O 4 nanoparticles were fabricated by magnetophoretic deposition of functionalized cobalt ferrite particles into porous alumina membrane. • The nanocomposite obtained presents an out-of-plane easy axis with a large remanent magnetization and coercitivity. • The high effective internal magnetic anisotropy contributes to the permanent bias along the wire axis. • The frequency ferromagnetic resonance ranges from 46.5 to 49.5 GHz, depending on the filling ratio of the membrane. • We have obtained a good agreement between Ansoft High Frequency Structure Simulator simulations and experimental results

  20. Magnetic and Structural Investigations of Nanocrystalline Cobalt-Ferrite

    Directory of Open Access Journals (Sweden)

    I. Sharifi

    2012-10-01

    Full Text Available Cobalt ferrite is an important magnetic material due to their large magneto-crystalline anisotropy, high cohercivity, moderate saturation magnetization and chemical stability.In this study, cobalt ferrites Nanoparticles have been synthesized by the co-precipitation method and a new microemulsion route. We examined the cation occupancy in the spinel structure based on the “Rietveld with energies” method. The Xray measurements revealed the production of a broad single ferrite cubic phase with the average particle sizes of about 12 nm and 7nm, for co-precipitation and micro-emulsion methods, respectively. The FTIR measurements between 400 and 4000 cm-1 confirmed the intrinsic cation vibrations of the spinelstructure for the two methods. Furthermore, the Vibrating Sample Magnetometer (VSM was carried out at room temperature to study the structural and magnetic properties. The results revealed that by changing the method from co-precipitation to the reverse micelle the material exhibits a softer magnetic behavior in such a way that both saturation magnetization and coercivity decrease from 58 to 29 emu/g and from 286 to 25 Oe, respectively.

  1. Features of simultaneous discharge of tungsten with nickel and cobalt

    International Nuclear Information System (INIS)

    Kotov, V.L.; Krivtsov, A.K.; Pavel'eva, L.A.; Zajtsev, A.L.

    1977-01-01

    Specific features of the kinetics of electrolytic codeposition of tungsten alloys with nickel and cobalt were investigated. Experiments were conducted with ammonia-citrate electrolytes having the following composition in g/1: (1)CoSO 4 x7H 2 O-60, Na 2 WO 4 x2H 2 O -70, citric acid-60, NH 4 OH to pH=6-7; (2) NiSO 4 x7H 2 O - from 1 to 20, Na 2 WO 4 x2H 2 O-50, citric acid-66, NH 4 OH, to pH=6-7. Dependences of tungsten content in the alloy on the concentration of citric acid and current densities are investigated. It is shown that intermediate tungsten oxides of lower oxidation degrees can be formed in the electrolyte. Experimental proofs are obtained of tungsten discharge into the alloy with cobalt and nickel from citrate solutions through the film of intermediate compounds, which forms in the near-cathode space

  2. Cobalt-doped nanohydroxyapatite: synthesis, characterization, antimicrobial and hemolytic studies

    Energy Technology Data Exchange (ETDEWEB)

    Tank, Kashmira P., E-mail: kashmira_physics@yahoo.co.in [Saurashtra University, Crystal Growth Laboratory, Physics Department (India); Chudasama, Kiran S.; Thaker, Vrinda S. [Saurashtra University, Bioscience Department (India); Joshi, Mihir J., E-mail: mshilp24@rediffmail.com [Saurashtra University, Crystal Growth Laboratory, Physics Department (India)

    2013-05-15

    Hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}; HAP) is a major mineral component of the calcified tissues, and it has various applications in medicine and dentistry. In the present investigation, cobalt-doped hydroxyapatite (Co-HAP) nanoparticles were synthesized by surfactant-mediated approach and characterized by different techniques. The EDAX was carried out to estimate the amount of doping in Co-HAP. The transmission electron microscopy result suggested the transformation of morphology from needle shaped to spherical type on increasing the doping concentration. The powder XRD study indicated the formation of a new phase of brushite for higher concentration of cobalt. The average particle size and strain were calculated using Williamson-Hall analysis. The average particle size was found to be 30-60 nm. The FTIR study confirmed the presence of various functional groups in the samples. The antimicrobial activity was evaluated against four organisms Pseudomonas aeruginosa and Shigella flexneri as Gram negative as well as Micrococcus luteus and Staphylococcus aureus as Gram positive. The hemolytic test result suggested that all samples were non-hemolytic. The photoluminescence study was carried out to identify its possible applicability as a fluorescent probe.

  3. Development and production of cobalt-60 sources for metallurgical application

    International Nuclear Information System (INIS)

    Oliveira, Paulo Fernando; Valente, Eduardo Sarmento; Maretti Junior, Fausto

    2002-01-01

    The CDTN has developed and produced 60 Co sources to be used in level controllers on continuous ingot casting. The sources used in these systems are sealed with a stainless steel revetment and have an useful life equivalent to one half life of the 60 Co (5.272 years). Each system of continuous ingot casting uses a source with one specified activity and different activation section. The sources have been imported with a very high cost due the special shields used to keep and transport them safety. One of its sources, with initial activity of 148 MBq, after being used for more than 5 years in one factory, was given to CDTN to carry out an activation section studies. After these studies be concluded CDTN/CNEN began the procedures to produce a new source in the IPR-R1 TRIGA Reactor, with an irradiation of one cobalt wire in the maximum flux region of the core. The same metallic cobalt wire was irradiated (10% of total activity), to determinate the necessary irradiation time to obtain the final activation. The CDTN developed too a stainless steel recipient with a aluminum nucleus, to seal and to guarantee the integrity of the source. (author)

  4. Cobalt Xanthate Thin Film with Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    İ. A. Kariper

    2013-01-01

    Full Text Available Cobalt xanthate thin films (CXTFs were successfully deposited by chemical bath deposition, onto amorphous glass substrates, as well as on p- and n-silicon, indium tin oxide, and poly(methyl methacrylate. The structure of the films was analyzed by far-infrared spectrum (FIR, mid-infrared (MIR spectrum, nuclear magnetic resonance (NMR, and scanning electron microscopy (SEM. These films were investigated from their structural, optical, and electrical properties point of view. Electrical properties were measured using four-point method, whereas optical properties were investigated via UV-VIS spectroscopic technique. Uniform distribution of grains was clearly observed from the photographs taken by scanning electron microscope (SEM. The transmittance was about 70–80% (4 hours, 50°C. The optical band gap of the CXTF was graphically estimated to be 3.99–4.02 eV. The resistivity of the films was calculated as 22.47–75.91 Ω·cm on commercial glass depending on film thickness and 44.90–73.10 Ω ·cm on the other substrates. It has been observed that the relative resistivity changed with film thickness. The MIR and FIR spectra of the films were in agreement with the literature analogues. The expected peaks of cobalt xanthate were observed in NMR analysis on glass. The films were dipped in chloroform as organic solvent and were analyzed by NMR.

  5. Impact of wastewater reuse on cobalt status in Egyptian environment.

    Science.gov (United States)

    Abdel-Sabour, M F

    2003-05-01

    Cobalt is used in the manufacture of alloys, catalysts in the petroleum industry, catalytic converters, and paint pigments. Thus the potential for Co releases into the environment is highly increased. Use of waste sludges and sewage effluent to fertilize and irrigate soils has also increased soil Co concentrations. Total cobalt contents of alluvial delta soil of Egypt show considerable variation ranging from 13.1 to 64.7 ppm. The impact of either wastewater irrigation or industrial activities on soil total Co was obvious due to accumulation of organic matter and solid waste in the surface soil samples. Food crops and vegetables should not be grown on soil highly contaminated by Co. It is noteworthy that the delayed neutron activation analysis (DNAA) technique could be used successfully for total Co determination due to its high sensitivity. It is quit clearly that dust samples of Cairo City contains higher Co level, as compared to Suez Canal Region (Ismailia, Port Said an El-Sues cities). The high values in Cairo City may be due to the existence of industries around the city and the intensive traffic. To minimize Co environmental hazards, waste effluents should be treated on site. Thus, levels of potentially toxic Co needs to be continuously monitored and should be removed during several treatment processes before the disposal of these wastes.

  6. Chromium Substituted Cobalt Ferrites by Glycine-Nitrates Process

    Directory of Open Access Journals (Sweden)

    Dana Gingasu

    2015-12-01

    Full Text Available Chromium substituted cobalt ferrites (CoFe2–xCrxO4, 0 ≤ x ≤ 2 were synthesized through solution combustion method using glycine as fuel, named glycine-nitrates process (GNP. As evidenced by X-ray diffraction data (XRD, single cubic spinel phase was formed for all CoFe2–xCrxO4 (0 ≤ x ≤ 2 series. The cubic lattice parameter (a decreases with increasing chromium content. Room temperature 57Fe Mössbauer spectra revealed the Fe3+ and Cr3+ site occupancy, the local hyperfine magnetic fields and the substitution of Fe3+ by Cr3+ in the lattice. Scanning electron microscopy (SEM showed a refinement of particle size with the increase of Cr3+ content. Magnetic measurements from 5 K to 120 K have shown a dropping in the saturation magnetization as the chromium content increases. This behaviour has been explained in terms of substitution of Fe3+ by Cr3+ in the cubic lattice of cobalt ferrite.

  7. [Allergy to nickel, chromium and cobalt after osteosynthesis].

    Science.gov (United States)

    Liebhart, J; Kuś, H; Martosz, M; Rutowski, R; Małolepszy, J; Obojski, A; Medrala, W

    2000-05-01

    Metals are known as a common cause of contact allergies. The prevalence of sensitisation to the composite metals makes for a potential risk of osteosynthesis complications in patients suffering from long bones fractures. In the study the prevalence of delayed allergy to nickel sulphate, potassium dichromate and cobalt was estimated as well as the relation to the osteosynthesis complications. The atopy prevalence was estimated too. Persons under examination were divided into 3 groups. I--treated with osteosynthesis without complications (n = 20), II--treated with osteosynthesis with synostosis complications (n = 16) and III--negative controls (n = 34). We estimated 5% prevalence of delayed allergy to nickel in group I, 6.25% in group II and 5.8% in group III. In patients exposed to chromium we observed delayed allergy prevalence of 5.8% in group I and 3% in group III. No allergy to chromium in group II was revealed. No allergy to cobalt in all groups was revealed. The prevalence of atopy in group II was rare (6.35%) when in group I it was 45% and in controls 32%. The more frequent occurrence of type IV allergy to metals in atopic patients was not confirmed. There was no difference between the prevalence of delayed allergy to metals in groups I and II. Only one case of secondary allergy to chromium was observed.

  8. Analysis of safety and economics for cobalt-60 production

    Energy Technology Data Exchange (ETDEWEB)

    Suh, D. S.; Jun, H. S. [Korea Electric Power Corporation, Seoul (Korea)

    2000-06-01

    The feasibility of Co-60 production in Wolsong Unit 1,2,3,4 was studied by reviewing its impact on plant safety and conformance to licensing basis, and by analyzing impact of Co-60 production on plant operation, initial investment capital, and operating costs and revenue. Design changes, equipment and tools needed for Co-60 production in Wolsong reactors and safety concerns in using cobalt adjuster rods were reviewed. There are several safety concerns in using cobalt adjuster rods are change in nuclear characteristics due to change in material in adjuster rods, deflagration potential in moderator cover gas and radiation control, however, it was estimated that the reactor conversion would not impose adverse impact on plant safety. In the economical aspect, although there is a relatively large uncertainty in estimating plant conversion cost, it was verified that, since Co-60 can be produced without any adverse impact on electricity production, in principal Co-60 production is an economically feasible business. 25 figs. (Author)

  9. Construction of an apparatus for nuclear orientation measurements at low temperatures. Application to neodymium-cobalt alloy

    International Nuclear Information System (INIS)

    Mayer, E.

    1965-10-01

    We describe experiments along which has been studied the anisotropy of γ radiations emitted by oriented nuclei. We have used the great hyperfine fields acting on nuclei in ferromagnetic metals so as to produce alignment at low temperature. By irradiation we obtained a few cobalt 60 nuclei in our samples which were then cooled down to 0,01 K. The anisotropic rate of the 1,33 MeV γ radiation was measured in function of the sample temperature, using as thermometer the anisotropy of γ radiation emitted by cobalt 60 nuclei in a cobalt single crystal. Cobalt 60 was lined up in a cobalt nickel alloy (40% Ni). The hyperfine field at the cobalt was measured compared to the effective field in metallic cobalt: Heff(Co Ni)/Heff(Co metal) = 0.71 ± 0.12. These results are in good agreement with specific heat measurements made previously. Cobalt 60 has been polarised in a neodymium-cobalt alloy (NdCo 5 ). The field at the cobalt in NdCo 5 has been measured compared to the field in metallic cobalt and taking the non-saturation into account we found 165000 oersteds 5 ) [fr

  10. Association between cobalt allergy and dermatitis caused by leather articles--a questionnaire study.

    Science.gov (United States)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus; Menné, Torkil; Johansen, Jeanne D

    2015-02-01

    Cobalt is a strong skin sensitizer and a prevalent contact allergen. Recent studies have recognized exposure to leather articles as a potential cause of cobalt allergy. To examine the association between contact allergy to cobalt and a history of dermatitis resulting from exposure to leather. A questionnaire case-control study was performed: the case group consisted of 183 dermatitis patients with a positive patch test reaction to cobalt chloride and a negative patch test reaction to potassium dichromate; the control group consisted of 621 dermatitis patients who did not react to either cobalt or chromium in patch testing. Comparisons were made by use of a χ(2) -test, Fisher's exact, and the Mann-Whitney test. Logistic regression analyses were used to test for associations while taking confounding factors into consideration. Leather was observed as the most frequent exposure source causing dermatitis in the case group. Although the case group significantly more often reported non-occupational dermatitis caused by leather exposure (p cobalt allergy and dermatitis caused by work-related exposure to leather. Our study suggests a positive association between cobalt allergy and a history of dermatitis caused by non-occupational exposure to leather articles. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Selective Area Band Engineering of Graphene using Cobalt-Mediated Oxidation.

    Science.gov (United States)

    Bazylewski, Paul F; Nguyen, Van Luan; Bauer, Robert P C; Hunt, Adrian H; McDermott, Eamon J G; Leedahl, Brett D; Kukharenko, Andrey I; Cholakh, Seif O; Kurmaev, Ernst Z; Blaha, Peter; Moewes, Alexander; Lee, Young Hee; Chang, Gap Soo

    2015-10-21

    This study reports a scalable and economical method to open a band gap in single layer graphene by deposition of cobalt metal on its surface using physical vapor deposition in high vacuum. At low cobalt thickness, clusters form at impurity sites on the graphene without etching or damaging the graphene. When exposed to oxygen at room temperature, oxygen functional groups form in proportion to the cobalt thickness that modify the graphene band structure. Cobalt/Graphene resulting from this treatment can support a band gap of 0.30 eV, while remaining largely undamaged to preserve its structural and electrical properties. A mechanism of cobalt-mediated band opening is proposed as a two-step process starting with charge transfer from metal to graphene, followed by formation of oxides where cobalt has been deposited. Contributions from the formation of both CoO and oxygen functional groups on graphene affect the electronic structure to open a band gap. This study demonstrates that cobalt-mediated oxidation is a viable method to introduce a band gap into graphene at room temperature that could be applicable in electronics applications.

  12. Thermal-fatigue and oxidation resistance of cobalt-modified Udimet 700 alloy

    International Nuclear Information System (INIS)

    Bizon, P.T.; Barrow, B.J.

    1986-04-01

    Comparative thermal-fatigue and oxidation resistances of cobalt-modified wrought Udimet 700 alloy (obtained by reducing the cobalt level by direct substitution of nickel) were determined from fluidized-bed tests. Bed temperatures were 1010 and 288 C (1850 and 550 C) for the first 5500 symmetrical 6-min cycles. From cycle 5501 to the 14000-cycle limit of testing, the heating bed temperature was increased to 1050 C (1922 F). Cobalt levels between 0 and 17 wt% were studied in both the bare and NiCrAlY overlay coated conditions. A cobalt level of about 8 wt% gave the best thermal-fatigue life. The conventional alloy specification is for 18.5% cobalt, and hence, a factor of 2 in savings of cobalt could be achieved by using the modified alloy. After 13500 cycles, all bare cobalt-modified alloys lost 10 to 13 percent of their initial weight. Application of the NiCrAlY overlay coating resulted in weight losses of 1/20 to 1/100 of that of the corresponding bare alloy

  13. Monolithic cobalt-doped carbon aerogel for efficient catalytic activation of peroxymonosulfate in water.

    Science.gov (United States)

    Hu, Peidong; Long, Mingce; Bai, Xue; Wang, Cheng; Cai, Caiyun; Fu, Jiajun; Zhou, Baoxue; Zhou, Yongfeng

    2017-06-15

    As an emerging carbonaceous material, carbon aerogels (CAs) display a great potential in environmental cleanup. In this study, a macroscopic three-dimensional monolithic cobalt-doped carbon aerogel was developed by co-condensation of graphene oxide sheets and resorcinol-formaldehyde resin in the presence of cobalt ions, followed by lyophilization, carbonization and thermal treatment in air. Cobalt ions were introduced as a polymerization catalyst to bridge the organogel framework, and finally cobalt species were retained as both metallic cobalt and Co 3 O 4 , wrapped by graphitized carbon layers. The material obtained after a thermal treatment in air (CoCA-A) possesses larger BET specific surface area and pore volume, better hydrophilicity and lower leaching of cobalt ions than that without the post-treatment (CoCA). Despite of a lower loading of cobalt content and a larger mass transfer resistance than traditional powder catalysts, CoCA-A can efficiently eliminate organic contaminants by activation of peroxymonosulfate with a low activation energy. CoCA-A can float beneath the surface of aqueous solution and can be taken out completely without any changes in morphology. The monolith is promising to be developed into an alternative water purification technology due to the easily separable feature. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Half-sandwich cobalt complexes in the metal-organic chemical vapor deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Georgi, Colin [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Hapke, Marko; Thiel, Indre [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Straße 29a, Rostock 18059 (Germany); Hildebrandt, Alexander [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Institute of Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz 09126 (Germany); Technische Universität Chemnitz, Center for Microtechnologies (ZfM), Chemnitz 09107 (Germany); Lang, Heinrich, E-mail: heinrich.lang@chemie.tu-chemnitz.de [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany)

    2015-03-02

    A series of cobalt half-sandwich complexes of type [Co(η{sup 5}-C{sub 5}H{sub 5})(L)(L′)] (1: L, L′ = 1,5-hexadiene; 2: L = P(OEt){sub 3}, L′ = H{sub 2}C=CHSiMe{sub 3}; 3: L = L′ = P(OEt){sub 3}) has been studied regarding their physical properties such as the vapor pressure, decomposition temperature and applicability within the metal-organic chemical vapor deposition (MOCVD) process, with a focus of the influence of the phosphite ligands. It could be shown that an increasing number of P(OEt){sub 3} ligands increases the vapor pressure and thermal stability of the respective organometallic compound. Complex 3 appeared to be a promising MOCVD precursor with a high vapor pressure and hence was deposited onto Si/SiO{sub 2} (100 nm) substrates. The resulting reflective layer is closed, dense and homogeneous, with a slightly granulated surface morphology. X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of metallic cobalt, cobalt phosphate, cobalt oxide and cobalt carbide. - Highlights: • Thermal studies and vapor pressure measurements of cobalt half-sandwich complexes was carried out. • Chemical vapor deposition with cobalt half-sandwich complexes is reported. • The use of Co-phosphites results in significant phosphorous-doped metallic layers.

  15. Selective Area Band Engineering of Graphene using Cobalt-Mediated Oxidation

    Science.gov (United States)

    Bazylewski, Paul F.; Nguyen, Van Luan; Bauer, Robert P.C.; Hunt, Adrian H.; McDermott, Eamon J. G.; Leedahl, Brett D.; Kukharenko, Andrey I.; Cholakh, Seif O.; Kurmaev, Ernst Z.; Blaha, Peter; Moewes, Alexander; Lee, Young Hee; Chang, Gap Soo

    2015-01-01

    This study reports a scalable and economical method to open a band gap in single layer graphene by deposition of cobalt metal on its surface using physical vapor deposition in high vacuum. At low cobalt thickness, clusters form at impurity sites on the graphene without etching or damaging the graphene. When exposed to oxygen at room temperature, oxygen functional groups form in proportion to the cobalt thickness that modify the graphene band structure. Cobalt/Graphene resulting from this treatment can support a band gap of 0.30 eV, while remaining largely undamaged to preserve its structural and electrical properties. A mechanism of cobalt-mediated band opening is proposed as a two-step process starting with charge transfer from metal to graphene, followed by formation of oxides where cobalt has been deposited. Contributions from the formation of both CoO and oxygen functional groups on graphene affect the electronic structure to open a band gap. This study demonstrates that cobalt-mediated oxidation is a viable method to introduce a band gap into graphene at room temperature that could be applicable in electronics applications. PMID:26486966

  16. Correlation between morphology and magnetic properties of electrochemically produced cobalt powder particles

    Directory of Open Access Journals (Sweden)

    Maksimović Vesna M.

    2015-01-01

    Full Text Available Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Electrodeposited cobalt powder were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, Energy Dispersive Spectroscopy (EDS analysis and SQUID magnetometry. It has been shown that morphology, structure and magnetic properties of cobalt particles are closely associated and can be easily controlled by adjusting process parameters of electrodeposition. Morphology of cobalt powder particles is strongly affected by hydrogen evolution reaction as a parallel reaction to cobalt electrodeposition. Depending on the applied current density, the two types of powder particles were formed: dendrites at lower and spongy-like particles at higher current densities. Morphologies and structures of powder particles are correlated with their magnetic properties, and compared with those of the bulk cobalt. In comparison with the properties of bulk cobalt, the obtained 3D structures exhibited a decreased saturation magnetization (MS, but an enhanced coercivity (HC which is explained by their peculiar morphology. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

  17. Model for cobalt 60/58 deposition on primary coolant piping in a boiling water reactor

    International Nuclear Information System (INIS)

    Dehollander, W.R.

    1979-01-01

    A first principles model for deposition of radioactive metals into the corrosion films of primary coolant piping is proposed. It is shown that the predominant mechanism is the inclusion of the radioactive species such as Cobalt 60 into the spinel structure of the corrosion film during the act of active corrosion. This deposition can occupy only a defined fraction of the available plus 2 valence sites of the spinel. For cobalt ions, this ratio is roughly 4.6 x 10 -3 of the total iron sites. Since no distinction is made between Cobalt 60, Cobalt 58, and Cobalt 59 in this process, the radioactivity associated with this inclusion is a function of the ratio of the radioactive species to the nonradioactive species in the water causing the corrosion of the pipe metal. The other controlling parameter is the corrosion rate of the pipe material. This can be a function of time, for example, and it shown that freshly descaled metal when exposed to the cobalt containing water can incorporate as much as 10 x 10 -3 cobalt ions per iron atom in the initial corrosion period. This has implications for the problem of decontaminating nuclear reactor piping. Equations and selected observations are presented without reference to any specifically identified reactor or utility, so as to protect any proprietary interest

  18. Microbiological Load Of Ethylene Oxide Sterilized Medical Devices And Its Elimination By Cobalt 60 Source

    International Nuclear Information System (INIS)

    Bashir, R.; Afroze, B.; Zulfiqar, H. F.; Saleem, R.; Saleem, F.; Aslam, F.; Naz, S.

    2016-01-01

    Objective: To determine the residing microbial flora of ethylene oxide (EtO) sterilized medical devices and optimization of safe dose of gamma radiation (Cobalt 60 source) for the complete elimination of microbial load. Study Design: Experimental study. Place and Duration of Study: Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan from September 2014 to June 2015. Methodology: Thirty-six samples of EtO sterilized medical devices of same batch of three different companies were collected for this study. Isolation and enumeration of microbes were done by using different selective and differential media. Gram staining and biochemically characterization by API 20 (Bio Merieux, France) kit was done for identification of the microorganisms. The medical devices having high microbial load were sent to Pakistan Radiation Services (PARAS) for gamma irradiations at 3 different selected doses (20 KGy, 25 KGy, and 30 KGy). Result: Different types of Gram positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus and Bacillus subtilis) were isolated from the EtO sterilized samples. Gram negative bacteria and fungi were not detected on these medical devices. Gamma irradiations Result showed that 30 KGy was optimized dose for complete elimination of microbial flora on endotracheal, Nelaton, and tracheostomy tubes. Conclusion: Gamma radiations (Co 60 source) effectively decontaminate the microbial flora on the equipment previously sterilized by the ethylene oxide gas; and 30 KGy is the optimized dose for all these medical devices. (author)

  19. Formation of DNA-network embedding ferromagnetic Cobalt nano-particles

    Science.gov (United States)

    Kanki, Teruo; Tanaka, Hidekazu; Shirakawa, Hideaki; Sacho, Yu; Taniguchi, Masateru; Lee, Hea-Yeon; Kawai, Tomoji; Kang, Nam-Jung; Chen, Jinwoo

    2002-03-01

    Formation of DNA-network embedding ferromagnetic Cobalt nano-particles T. Kanki, Hidekazu. Tanaka, H. Shirakawa, Y. Sacho, M. Taniguchi, H. Lee, T. Kawai The Institute of Scientific and Industrial Research, Osaka University, Japan and Nam-Jung Kang, Jinwoo Chen Korea Advanced Institute of Science and Technology (KAIST), Korea DNA can be regarded as a naturally occurring and highly specific functional biopolymer and as a fine nano-wire. Moreover, it was found that large-scale DNA networks can be fabricated on mica surfaces. By using this network structure, we can expect to construct nano-scale assembly of functional nano particle, for example ferromagnetic Co nano particles, toward nano scale spin-electronics based on DNA circuits. When we formed DNA network by 250mg/ml DNA solution of poly(dG)-poly(dC) including ferromagnetic Co nano particles (diameter of 12nm), we have conformed the DNA network structure embedding Co nano-particles (height of about 12nm) by atomic force microscopy. On the other hand, we used 100mg/ml DNA solution, DNA can not connect each other, and many Co nano-particles exist without being embedded.

  20. Evaluation of mechanical properties of a low-cobalt wrought superalloy

    Science.gov (United States)

    Dreshfield, R. L.

    1993-08-01

    In the late 1970s and early 1980s, cobalt was subjected to significant supply and market pressures. Those pressures caused renewed attention to the use of cobalt in aircraft engines. A NASA-sponsored program called Conservation of Strategic Aerospace Materials (COSAM) was created in response to the supply problems with cobalt and other aerospace metals. Among the work performed in the COSAM program and simultaneously by others were several studies on laboratory-size heats of wrought nickel-base super-alloys. These studies suggested that the cobalt levels of the alloys might be reduced by about half, with minimal negative impact on mechanical properties. The Lewis Research Center procured a 1365-kg (3000-lb) heat of a modified Waspaloy having a reduced cobalt level. This article reports the results of a program performed at four gas turbine manufacturers which evaluated the mechanical properties of forgings fabricated from that heat. The alloy chemistry selected reduced the nominal cobalt level from 13.5 to 7.75 wt%. To compensate for the anticipated strength reduction caused by a slight reduction in the amount of γ, the nominal aluminum was increased from 1.3 to 1.5% and the titanium was increased from 3.0 to 3.2%. The increase in aluminum and titanium were intended to increase the amount of γ in the al-loy. Tensile, creep-rupture, low-cycle fatigue, and cyclic crack growth tests were performed. In addition the effect of hydrogen on the alloy was determined. It was concluded that, in the event of a cobalt short-age, a low-cobalt modification of Waspaloy alloy could be substituted for Waspaloy with little develop-ment in those applications that are not creep-rupture limited. With some additional development to better control the grain size, it is probable that most of the current Waspaloy requirements might be met with a lower cobalt alloy.

  1. Piezoelectric properties and thermal stabilities of cobalt-modified potassium bismuth titanate

    International Nuclear Information System (INIS)

    Guo, Zhen-Lei; Wang, Chun-Ming; Zhao, Tian-Long; Yu, Si-Long; Cao, Zhao-Peng

    2013-01-01

    The cobalt-modified potassium bismuth titanate (K 0.5 Bi 4.5 Ti 4 O 15 , KBT) piezoelectric ceramics have been prepared using conventional solid–state reaction. X-ray diffraction analysis revealed that the cobalt-modified KBT ceramics have a pure four-layer (m = 4) Aurivillius-type structure. The dielectric, ferroelectric, and piezoelectric properties of cobalt-modified KBT ceramics were investigated in detail. The piezoelectric activities of KBT ceramics were significantly improved by the cobalt modification. The reasons for piezoelectric activities enhancement with cobalt modification were given. The piezoelectric coefficient d 33 and Curie temperature T c for the 5 mol% cobalt-modified KBT ceramics (KBT-Co5) were found to be 28 pC/N and 575 °C, respectively. The DC resistivity, frequency constants (N p and N t ), and electromechanical properties at elevated temperature were investigated, indicating the cobalt-modified KBT piezoelectric ceramics possess stable piezoelectric properties up to 500 °C. The results show the cobalt-modified KBT ceramics are potential materials for high temperature piezoelectric applications. - Highlights: • We examine the piezoelectric properties of the cobalt-modified K 0.5 Bi 4.5 Ti 4 O 15 . • A high level of piezoelectric activities (d 33 = 28 pC/N) are obtained. • High Curie temperature (T c = 575 °C) is acquired for the optimal composition. • The Co-modified K 0.5 Bi 4.5 Ti 4 O 15 is promising as high temperature materials

  2. Controlling of morphology and electrocatalytic properties of cobalt oxide nanostructures prepared by potentiodynamic deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Akhtari, Keivan [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Soltanian, Saied [Department of Physics, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2013-07-01

    Electrodeposited cobalt oxide nanostructures were prepared by Repetitive Triangular Potential Scans (RTPS) as a simple, remarkably fast and scalable potentiodynamic method. Electrochemical deposition of cobalt oxide nanostructures onto GC electrode was performed from aqueous Co(NO{sub 3}){sub 2}, (pH 6) solution using cyclic voltammetry method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology of fabricated nanostructures. The evaluation of electrochemical properties of deposited films was performed using cyclic voltametry (CV) and impedance spectroscopy (IS) techniques. The analysis of the experimental data clearly showed that the variations of potential scanning ranges during deposition process have drastic effects on the geometry, chemical structure and particle size of cobalt oxide nanoparticles. In addition, the electrochemical and electrocatalytic properties of prepared nanostructures can be controlled through applying different potential windows in electrodeposition process. The imaging and voltammetric studies suggested to the existence of at least three different shapes of cobalt-oxide nanostructures in various potential windows applied for electrodeposition. With enlarging the applied potential window, the spherical-like cobalt oxide nanoparticles with particles sizes about 30–50 nm changed to the grain-like structures (30 nm × 80 nm) and then to the worm-like cobalt oxide nanostructures with 30 nm diameter and 200–400 nm in length. Furthermore, the roughness of the prepared nanostructures increased with increasing positive potential window. The GC electrodes modified with cobalt oxide nanostructures shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} and As (III) oxidation. The electrocatalytic activity of cobalt oxide nanostructures prepared at more positive potential window toward hydrogen peroxide oxidation was increased, while for As(III) oxidation the electrocatalytic

  3. Controlling of morphology and electrocatalytic properties of cobalt oxide nanostructures prepared by potentiodynamic deposition method

    International Nuclear Information System (INIS)

    Hallaj, Rahman; Akhtari, Keivan; Salimi, Abdollah; Soltanian, Saied

    2013-01-01

    Electrodeposited cobalt oxide nanostructures were prepared by Repetitive Triangular Potential Scans (RTPS) as a simple, remarkably fast and scalable potentiodynamic method. Electrochemical deposition of cobalt oxide nanostructures onto GC electrode was performed from aqueous Co(NO 3 ) 2 , (pH 6) solution using cyclic voltammetry method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology of fabricated nanostructures. The evaluation of electrochemical properties of deposited films was performed using cyclic voltametry (CV) and impedance spectroscopy (IS) techniques. The analysis of the experimental data clearly showed that the variations of potential scanning ranges during deposition process have drastic effects on the geometry, chemical structure and particle size of cobalt oxide nanoparticles. In addition, the electrochemical and electrocatalytic properties of prepared nanostructures can be controlled through applying different potential windows in electrodeposition process. The imaging and voltammetric studies suggested to the existence of at least three different shapes of cobalt-oxide nanostructures in various potential windows applied for electrodeposition. With enlarging the applied potential window, the spherical-like cobalt oxide nanoparticles with particles sizes about 30–50 nm changed to the grain-like structures (30 nm × 80 nm) and then to the worm-like cobalt oxide nanostructures with 30 nm diameter and 200–400 nm in length. Furthermore, the roughness of the prepared nanostructures increased with increasing positive potential window. The GC electrodes modified with cobalt oxide nanostructures shows excellent electrocatalytic activity toward H 2 O 2 and As (III) oxidation. The electrocatalytic activity of cobalt oxide nanostructures prepared at more positive potential window toward hydrogen peroxide oxidation was increased, while for As(III) oxidation the electrocatalytic activity decreased

  4. Influence of cobalt precursor and of its decomposition on the synthesis of cobalt nano-particles on silica for the optimization of the Fischer-Tropsch catalysts; Influence du precurseur de cobalt et de sa decomposition sur la synthese de nanoparticules de cobalt sur silice dans le cadre de l'optimisation des catalyseurs Fischer-Tropsch

    Energy Technology Data Exchange (ETDEWEB)

    Girardon, J.S.; Khodakov, A.Y.; Constant-Griboval, A. [Universite des sciences et technologies de Lille, Lab. de catalyse de Lille, UMR 8010, 59 - Villeneuve D' Ascq (France)

    2004-07-01

    In order to synthesize Fischer-Tropsch catalysts more active and selective in heavy hydrocarbons, the understanding at the molecular level of the chemical processes which occur during synthesis is a strategic stake. This work is based in one hand on the use of different cobalt precursors (acetate (Ac) and nitrate (N)) and in another hand on the influence of the decomposition temperature of these precursors on the formation of cobalt nano-particles. An UV-visible study shows that the impregnated cobalt coming from the two types of precursors is in an octahedral environment before its decomposition. The XRD, UV-visible and XANES-EXAFS studies show, after decomposition in air (400 C, 5 hours), that the sample prepared from cobalt nitrate (N400) presents a Co{sub 3}O{sub 4} phase. This phase is not detected in the case of the cobalt acetate (Ac400). These observations are in agreement with the results of the catalytic tests which show that the solid N400 is eight times more than the solid Ac400. A softer decomposition at 170 C during 70 hours of the cobalt acetate (Ac170) has allowed to minimize the formation of cobalt silicate for Co{sub 3}O{sub 4} and to increase of more than three times the catalytic activity. In the case of cobalt nitrate, the XRD analysis of the solids obtained after a softer decomposition (150 C and 100 C) has revealed a decrease of the size of the cobalt nano-particles. The catalytic conversion remains the same than with N400 but a better C{sub 5}{sup +} selectivity is observed. (O.M.)

  5. The effects of cobalt on the development, oxidative stress, and apoptosis in zebrafish embryos.

    Science.gov (United States)

    Cai, Guiquan; Zhu, Junfeng; Shen, Chao; Cui, Yimin; Du, Jiulin; Chen, Xiaodong

    2012-12-01

    Metal-on-metal hip arthroplasty has been performed with increasing frequency throughout the world, particularly in younger and more active patients, including women of childbearing age. The potential toxicity of cobalt exposure on fetus is concerned since cobalt ions generated by metal-on-metal bearings can traverse the placenta and be detected in fetal blood and amniotic fluid. This study examined the effects of cobalt exposure on early embryonic development and the mechanisms underlying its toxicity. Zebrafish embryos were exposed to a range of cobalt concentrations (0-100 mg/L) between 1 and 144 h postfertilization. The survival and early development of embryos were not significantly affected by cobalt at concentrations 100 μg/L) displayed reduced survival rates and abnormal development, including delayed hatching, aberrant morphology, retarded growth, and bradycardia. Furthermore, this study examined oxidative stress and apoptosis in embryos exposed to cobalt at concentrations of 0-500 μg/L. Lipid peroxidation levels were increased in cobalt-treated embryos at concentrations of 100 and 500 μg/L. The mRNA levels of catalase, superoxide dismutase 2, p53, caspase-3, and caspase-9 genes were upregulated in a dose-dependent manner. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays also revealed abnormal apoptotic signals in the brain, trunk, and tail when treated with 500 μg/L cobalt. These data suggest that oxidative stress and apoptosis are associated with cobalt toxicity in zebrafish embryos.

  6. Structural and magnetic properties of the products of the transformation of ferrihydrite: Effect of cobalt dications

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, K.I. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Unidad Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Ramos Arizpe, Coahuila C.P.25000, México (Mexico); Pariona, N. [Red de Estudios Moleculares Avanzados, Instituto de Ecología A.C., Carretera Antigua a Coatepec 351, El Haya, 91070 Xalapa, Veracruz (Mexico); Martinez, A.I., E-mail: arturo.martinez@cinvestav.edu.mx [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Unidad Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Ramos Arizpe, Coahuila C.P.25000, México (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Río de Janeiro 22290-180 (Brazil); Herrera-Trejo, M. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Unidad Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Ramos Arizpe, Coahuila C.P.25000, México (Mexico); Perry, Dale L. [Mailstop 70A1150, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

    2017-05-01

    The effect of cobalt dications on the transformation of 2-line ferrihydrite (2LF) has been studied. The products of the transformation reaction were characterized by X-ray diffraction, Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), magnetometry, and first-order reversal curve (FORC) diagrams. It was found that the concentration of cobalt dications plays an important role on the structural and magnetic properties of the products; i.e., for low cobalt concentrations, cobalt-substituted hematite is formed, while higher concentrations promote the formation of cobalt-substituted magnetite. Structural results revealed that formation of other iron oxide polymorphs is avoided and residual 2LF is always present in the final products. In this way, hematite/2LF and magnetite/2LF nanocomposites were formed. For all the samples, magnetic measurements yielded non-saturated hysteresis loops at a maximum field of 12 kOe. For cobalt-substituted hematite/2LF samples, FORC diagrams revealed the presence of multiple single-domain (SD) components which generate interaction coupling between SD with low and high coercivity. Moreover, for cobalt-substituted magnetite/2LF samples, the FORC diagrams revealed the components of wasp-waist hysteresis loops which consist of mixtures of SD and superparamagnetic particles. One of the goals of the present study is the rigorous, experimental documentation of ferrihydrite/hematite mixtures as a function of reaction conditions for use as analytical standards research. - Highlights: • Co(II) may stabilize ferrihydrite against transformation to more crystalline oxides. • The transformation is strongly dependent on the Co(II)/Fe(III) atomic ratio. • Cobalt-substituted hematite and cobalt-substituted magnetite were the products. • FORC diagrams identified the interaction coupling between single-domains.

  7. Metal- versus Ligand-Centered Oxidations in Phenolato-Vanadium and -Cobalt Complexes: Characterization of Phenoxyl-Cobalt(III) Species.

    Science.gov (United States)

    Sokolowski, Achim; Adam, Britta; Weyhermüller, Thomas; Kikuchi, Akihiro; Hildenbrand, Knut; Schnepf, Robert; Hildebrandt, Peter; Bill, Eckhard; Wieghardt, Karl

    1997-08-13

    The coordination chemistry of the pendent-arm macrocycles 1,4,7-tris(3,5-dimethyl-2-hydroxybenzyl)-1,4,7-triazacyclononane, L(Me)H(3), 1,4,7-tris(3,5-di-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononane, L(Bu)H(3), 1,4,7-tris(3-tert-butyl-5-methoxy-2-hydroxybenzyl)-1,4,7-triazacyclononane, L(OCH)()3H(3), and Tolman's ligand 1,4-diisopropyl-7-(3,5-di-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononane, L(Pr)H, with vanadium and cobalt(III) has been studied. The following complexes containing a fac-N(3)O(3) donor set have been synthesized: [L(Me)V(III)] (1), [L(Me)V(IV)]PF(6) (2), [(L(Me)H)V(V)(O)]PF(6) (3), [L(Bu)V(IV)]PF(6) (4), [L(OCH)()3V(IV)]PF(6) (5), [L(Me)Co(III)] (6), [L(Bu)Co(III)] (7), [L(OCH)()3Co(III)] (8). In addition, two complexes containing the L(Pr)Co(III) fragment have been prepared: [L(Pr)Co(III)(acac)](ClO(4)) (9) and [L(Pr)Co(III)(Cl(4)cat)].CH(3)CN (10), where acac(-) represents the ligand pentane-2,4-dionate and Cl(4)cat(2)(-) is tetrachlorocatecholate. Complexes 9 and 10 have been characterized by single-crystal X-ray crystallography: 9 crystallizes in the triclinic space group P&onemacr; with a = 9.493(1) Å, b = 9.760(1) Å, c = 18.979(2) Å, alpha = 88.57(1) degrees, beta = 78.60(1) degrees, gamma = 79.24(1) degrees, V = 1693.3(3) Å(3), and Z = 2; 10 crystallizes in the monoclinic space group P2(1)/n with a = 10.184(2) Å, b = 24.860(5) Å, c = 14.872(3) Å, beta = 97.95(3) degrees, V = 3729(1) Å(3), and Z = 4. Electrochemically, complexes 2, 4, and 5 can be reversibly oxidized by one electron, yielding vanadium(V), and one-electron-reduced, affording vanadium(III) species; 3 can be reduced to [L(Me)HV(IV)(O)]. These redox processes are shown to be metal-centered. In contrast, the cyclic voltammograms of 7 and 8 display three reversible one-electron oxidations. For the monocations [7](*)(+) and [8](*)(+), EPR and UV-vis spectroscopies reveal that these are phenoxyl-cobalt(III) species. Thus, the redox processes are ligand

  8. Cobalt separation by Alphaproteobacterium MTB-KTN90: magnetotactic bacteria in bioremediation.

    Science.gov (United States)

    Tajer-Mohammad-Ghazvini, Parisa; Kasra-Kermanshahi, Rouha; Nozad-Golikand, Ahmad; Sadeghizadeh, Majid; Ghorbanzadeh-Mashkani, Saeid; Dabbagh, Reza

    2016-12-01

    Bioremediation of toxic metals by magnetotactic bacteria and magnetic separation of metal-loaded magnetotactic bacteria are of great interest. This bioprocess technique is rapid, efficient, economical, and environmentally friendly. In this study, cobalt removal potential of a novel isolated magnetotactic bacterium (Alphaproteobacterium MTB-KTN90) as a new biosorbent was investigated. The effects of various environmental parameters in the cobalt removal and the technique of magnetic separation of cobalt-loaded bacterial cells were studied. Cobalt removal by MTB-KTN90 was very sensitive to pH solution; higher biosorption capacity was observed around pH 6.5-7.0. When biomass concentration increased from 0.009 to 0.09 g/l, the biosorption efficiency increased from 13.87 % to 19.22 %. The sorption of cobalt by MTB-KTN90 was rapid during the first 15 min (859.17 mg/g dry weight). With the increasing of cobalt concentrations from 1 to 225 mg/l, the specific cobalt uptake increased. Maximum cobalt removal (1160.51 ± 15.42 mg/g dry weight) took place at optimum conditions; pH 7.0 with initial cobalt concentration of 115 mg/l at 60 min by 0.015 g/l of dry biomass. The results showed maximum values for constants of Langmuir and Freundlich models so far. The biosorption mechanisms were studied with FTIR, PIXE, and FESEM analysis. Cobalt-loaded MTB-KTN90 had ability to separate from solution by a simple magnetic separator. Magnetic response in MTB-KTN90 is due to the presence of unique intracellular magnetic nanoparticles (magnetosomes). The orientation magnetic separation results indicated that 88.55 % of cobalt was removed from solution. Consequently, Alphaproteobacterium MTB-KTN90 as a new biosorbent opens up good opportunities for the magnetic removal of cobalt from the polluted aquatic environments.

  9. Caprine hepatic lipidosis induced through the intake of low levels of dietary cobalt.

    Science.gov (United States)

    Johnson, Eugene H; Al-Habsi, Khalid; Kaplan, Evelyn; Srikandakumar, Anandarajah; Kadim, Isam T; Annamalai, Kanthi; Al-Busaidy, Rashid; Mahgoub, Osman

    2004-09-01

    Forty-one, 10-week-old newly weaned goats were randomly allocated into two groups, namely control (n=22) and treated (n=19). Kids in both groups were fed Rhodegrass hay ad libitum that contained lipidosis associated with low liver levels of cobalt. Only one (5.3%) of the treated goats developed hepatic lipidosis. Contrary to previous reports that suggested that goats are less sensitive to low levels of dietary cobalt than sheep, it is apparent that this is not the case with Omani goats. This is the first report of the induction of hepatic lipidosis in goats due to feeding low levels of cobalt in their diet.

  10. Strontium and cesium extraction into hydrocarbons using alkyl cobalt dicarbollide and polyethylene glycols

    International Nuclear Information System (INIS)

    Chamberlin, R.M.; Abney, K.D.

    1999-01-01

    The extraction of strontium and cesium ions from high ionic strength acid, base, and salt solutions into an organic extractant consisting of alkyl cobalt dicarbollide and polyethylene glycol (PEG) in diethylbenzene was investigated. Adding hexaethylene glycol or PEG-400 improved the strontium extraction ≥ 100-fold, while cesium extraction was decreased at high PEG concentrations. The extractions are rapid and selective, even in the presence of molar concentrations of sodium ion, suggesting that alkyl cobalt dicarbollide extractants are useful for the treatment of alkaline nuclear wastes. A method for the synthesis of tetra-n-hexyl(cobalt dicarbollide) is described. (author)

  11. Supported, Alkali-Promoted Cobalt Oxide Catalysts for NOx Removal from Coal Combustion Flue Gases

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle

    2005-12-31

    A series of cobalt oxide catalysts supported on alumina ({gamma}-Al{sub 2}O{sub 3}) were synthesized with varying contents of cobalt and of added alkali metals, including lithium, sodium, potassium, rubidium, and cesium. Unsupported cobalt oxide catalysts and several cobalt oxide catalysts supported ceria (CeO{sub 2}) with varying contents of cobalt with added potassium were also prepared. The catalysts were characterized with UV-visible spectroscopy and were examined for NO{sub x} decomposition activity. The CoO{sub x}/Al{sub 2}O{sub 3} catalysts and particularly the CoO{sub x}/CeO{sub 2} catalysts show N{sub 2}O decomposition activity, but none of the catalysts (unsupported Co{sub 3}O{sub 4} or those supported on ceria or alumina) displayed significant, sustained NO decomposition activity. For the Al{sub 2}O{sub 3}-supported catalysts, N{sub 2}O decomposition activity was observed over a range of reaction temperatures beginning about 723 K, but significant (>50%) conversions of N{sub 2}O were observed only for reaction temperatures >900 K, which are too high for practical commercial use. However, the CeO{sub 2}-supported catalysts display N{sub 2}O decomposition rates similar to the Al{sub 2}O{sub 3}-supported catalysts at much lower reaction temperatures, with activity beginning at {approx}573 K. Conversions of >90% were achieved at 773 K for the best catalysts. Catalytic rates per cobalt atom increased with decreasing cobalt content, which corresponds to increasing edge energies obtained from the UV-visible spectra. The decrease in edge energies suggests that the size and dimensionality of the cobalt oxide surface domains increase with increasing cobalt oxide content. The rate data normalized per mass of catalyst that shows the activity of the CeO{sub 2}-supported catalysts increases with increasing cobalt oxide content. The combination of these data suggest that supported cobalt oxide species similar to bulk Co{sub 3}O{sub 4} are inherently more active than

  12. Li-ion battery recycling and cobalt flow analysis in Japan

    OpenAIRE

    Asari, Misuzu; Sakai, Shin-ichi

    2013-01-01

    Batteries sometimes contain precious or toxic substances (e.g. nickel, cobalt, lead, mercury, cadmium). However, the collection and recycling rate of small batteries were low in Japan. We focus on cobalt in lithium ion (Li-ion) batteries and conduct chemical analysis, questioner survey and flow analysis in Japan.Results of chemical analysis showed that the concentration of cobalt in Li-ion batteries was around 20% regardless of the year manufactured or the manufacturer. As a result of the con...

  13. Cobalt, manganese, and iron near the Hawaiian Islands: A potential concentrating mechanism for cobalt within a cyclonic eddy and implications for the hybrid-type trace metals

    Science.gov (United States)

    Noble, Abigail E.; Saito, Mak A.; Maiti, Kanchan; Benitez-Nelson, Claudia R.

    2008-05-01

    The vertical distributions of cobalt, iron, and manganese in the water column were studied during the E-Flux Program (E-Flux II and III), which focused on the biogeochemistry of cold-core cyclonic eddies that form in the lee of the Hawaiian Islands. During E-Flux II (January 2005) and E-Flux III (March 2005), 17 stations were sampled for cobalt ( n=147), all of which demonstrated nutrient-like depletion in surface waters. During E-Flux III, two depth profiles collected from within a mesoscale cold-core eddy, Cyclone Opal, revealed small distinct maxima in cobalt at ˜100 m depth and a larger inventory of cobalt within the eddy. We hypothesize that this was due to a cobalt concentrating effect within the eddy, where upwelled cobalt was subsequently associated with sinking particulate organic carbon (POC) via biological activity and was released at a depth coincident with nearly complete POC remineralization [Benitez-Nelson, C., Bidigare, R.R., Dickey, T.D., Landry, M.R., Leonard, C.L., Brown, S.L., Nencioli, F., Rii, Y.M., Maiti, K., Becker, J.W., Bibby, T.S., Black, W., Cai, W.J., Carlson, C.A., Chen, F., Kuwahara, V.S., Mahaffey, C., McAndrew, P.M., Quay, P.D., Rappe, M.S., Selph, K.E., Simmons, M.P., Yang, E.J., 2007. Mesoscale eddies drive increased silica export in the subtropical Pacific Ocean. Science 316, 1017-1020]. There is also evidence for the formation of a correlation between cobalt and soluble reactive phosphorus during E-Flux III relative to the E-Flux II cruise that we suggest is due to increased productivity, implying a minimum threshold of primary production below which cobalt-phosphate coupling does not occur. Dissolved iron was measured in E-Flux II and found in somewhat elevated concentrations (˜0.5 nM) in surface waters relative to the iron depleted waters of the surrounding Pacific [Fitzwater, S.E., Coale, K.H., Gordon, M.R., Johnson, K.S., Ondrusek, M.E., 1996. Iron deficiency and phytoplankton growth in the equatorial Pacific. Deep

  14. Size-dependent antimicrobial properties of the cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Žalnėravičius, Rokas [State Research Institute Center for Physical Sciences and Technology (Lithuania); Paškevičius, Algimantas [Nature Research Centre, Laboratory of Biodeterioration Research (Lithuania); Kurtinaitiene, Marija; Jagminas, Arūnas, E-mail: arunas.jagminas@ftmc.lt [State Research Institute Center for Physical Sciences and Technology (Lithuania)

    2016-10-15

    The growing resistance of bacteria to conventional antibiotics elicited considerable interest to non-typical drugs. In this study, antimicrobial investigations were performed on low-size dispersion cobalt ferrite nanoparticles (Nps) fabricated by co-precipitation approach in several average sizes, in particular, 15.0, 5.0, and 1.65 nm. A variety of experimental tests demonstrated that the size of these Nps is determinant for antimicrobial efficiency against S. cerevisiae and several Candida species, in particular, C. parapsilosis, C. krusei, and C. albicans. The small and ultra-small fractions of CoFe{sub 2}O{sub 4} Nps possess especially strong antimicrobial activity against all tested microorganisms. The possible reasons are discussed. Nps were characterized by means of transmission and high-resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and atomic force microscopy, chemical analysis and magnetic measurements.Graphical Abstract.

  15. Coordination compounds of cobalt and cadmium with isobutyric acid amide

    Energy Technology Data Exchange (ETDEWEB)

    Tsivadze, A.Yu.; Ivanova, I.S.; Solovkina, O.A. (AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

    1983-06-01

    Coordination compounds of cobalt and cadmium with isobutyric acid amide (IBAA) of Co(NCS)/sub 2/x(IBAA)/sub 2/(H/sub 2/O)/sub 2/, CoCl/sub 2/(IBAA)/sub 4/, CoI/sub 2/(IBAA)/sub 8/(H/sub 2/O)/sub 2/, CdI/sub 2/(IBAA)/sub 2/ composition have been synthesized and characterized. Their infrared absorption spectra (200-400 cm/sup -1/), electron reflection spectra (200-750 nm) were studied. It is shown that in all compounds there are IBAA molecUles coordinated through an oxygen atom. Thiocyanogroups are coordinated through nitrogen atoms.

  16. SSDL Argentina: Dosimetric intercomparison programme for cobalt 60 therapy units

    International Nuclear Information System (INIS)

    Saravi, M.; Papadopulos, S.; Mugliaroli, H.

    1996-01-01

    Thermoluminescence dosimeters (TLD) are widely used to verify absorbed dose delivered from radiation therapy beams. The Secondary Standard Dosimetry Laboratory (SSDL) of Argentina uses TLD for its mailed dose intercomparison programme for cobalt 60 radiation therapy units. Results obtained since 1978 as well as causes of dose discrepancies greater than 5% are analyzed. Results of the external quality control performed by the IAEA for this programme indicate that the dose evaluated by the SSDL TLD service for the participating centers is about 1% lower than that evaluated by the IAEA TLD service. This deviation is accepted taking on account that a ± 2% dose uncertainty for TLD dosimetry is reasonable. (author). 5 refs, 5 figs, 2 tabs

  17. Cobalt uptake and binding in human red blood cells

    DEFF Research Database (Denmark)

    Simonsen, Lars Ole; Brown, Anthony M; Harbak, Henrik

    2011-01-01

    A23187 mediates a rapid equilibration of Co(2+) across the cell membrane leading to a marked accumulation, reflecting effective cytoplasmic buffering. The fraction (a(Co)) of total cell cobalt being present as free, ionized Co(2+) is estimated at a(Co)=0.01 from the equilibrium distribution...... reversibly bound, being releasable by excess extracellular EGTA in the presence of A23187, and partly tightly bound, remaining in the cells even at high ionophore concentrations. The tightly bound fraction builds up over time, and is larger and develops earlier in fed cells compared to ATP-depleted cells......, compared with timed or in-competition whole-blood and serum analysis, an average value for the exposure over the last couple of months....

  18. Cross calibration of Cobalt Self-Powered Neutron Detectors

    International Nuclear Information System (INIS)

    Marshall, R.K.

    1979-01-01

    The sensitivities of Cobalt Self-Powered Neutron Detectors were measured in both the Coupled Fast Reactivity Measurements Facility (CFRMF) at INEL and in the General Electric Nuclear Test Reactor (NTR) near Pleasanton, California to obtain a comparison of detector sensitivities measured in different reactors. The sensitivities of two different lots of SPNDs from the same production run were measured. One lot of 26 SPNDs was measured in the CFRMF, the other lot of 28 was measured in the NTR. The average sensitivity of the lot measured in the NTR was 3.9% higher than that measured in the CFRMF. In addition, the sensitivities of 11 of the 26 SPNDs measured in the CFRMF were also measured in the NTR. The average sensitivity for these 11 detectors was 7.2% higher than that for the same detectors measured in the CFRMF

  19. Cobalt catalyzed hydroesterification of a wide range of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Van Rensburg, H.; Hanton, M.; Tooze, R.P.; Foster, D.F. [Sasol Technology UK, St Andrews (United Kingdom)

    2011-07-01

    Petrochemical raw materials are an essential raw material for the production of detergents with a substantial portion of synthetic fatty alcohols being produced via hydroformylation of oil or coal derived olefins. Carbonylation processes other than hydroformylation have to date not been commercially employed for the production of fatty esters or alcohols. In this document we highlight the opportunities of converting olefins to esters using cobalt catalyzed alkoxycarbonylation. This process is highly versatile and applicable to a wide range of olefins, linear or branched, alpha or internal in combination with virtually any chain length primary or secondary alcohol allowing the synthesis of a diverse array of compounds such as ester ethoxylated surfactants, methyl branched detergents, lubricants and alkyl propanoates. Furthermore, alkoxycarbonylation of a broad olefin/paraffin hydrocarbon range could be used to produce the corresponding broad cut detergent alcohols. (orig.)

  20. Enantioselective Epoxide Polymerization Using a Bimetallic Cobalt Catalyst

    KAUST Repository

    Thomas, Renee M.

    2010-11-24

    A highly active enantiopure bimetallic cobalt complex was explored for the enantioselective polymerization of a variety of monosubstituted epoxides. The polymerizations were optimized for high rates and stereoselectivity, with s-factors (kfast/kslow) for most epoxides exceeding 50 and some exceeding 300, well above the threshold for preparative utility of enantiopure epoxides and isotactic polyethers. Values for mm triads of the resulting polymers are typically greater than 95%, with some even surpassing 98%. In addition, the use of a racemic catalyst allowed the preparation of isotactic polyethers in quantitative yields. The thermal properties of these isotactic polyethers are presented, with many polymers exhibiting high T m values. This is the first report of the rapid synthesis of a broad range of highly isotactic polyethers via the enantioselective polymerization of racemic epoxides. © 2010 American Chemical Society.

  1. Silylation of Dinitrogen Catalyzed by Hydridodinitrogentris(TriphenylphosphineCobalt(I

    Directory of Open Access Journals (Sweden)

    Wojciech I. Dzik

    2016-07-01

    Full Text Available Recently, homogeneous cobalt systems were reported to catalyze the reductive silylation of dinitrogen. In this study the investigations on the silylation of dinitrogen catalyzed by CoH(PPh33N2 are presented. We show that in the presence of the title compound, the reaction of N2 with trimethylsilylchloride and sodium yields, on average, 6.7 equivalents of tris(trimethylsilylamine per Co atom in THF (tetrahydrofuran. The aim was to elucidate whether the active catalyst is: (a the [Co(PPh33N2]− anion formed after two-electron reduction of the title compound; or (b a species formed via decomposition of CoH(PPh33N2 in the presence of the highly reactive substrates. Time profile, and IR and EPR spectroscopic investigations show instability of the pre-catalyst under the applied conditions which suggests that the catalytically active species is formed through in situ modification of the pre-catalyst.

  2. Emission flame spectrophotometry of chromium, cobalt, nickel trace amounts

    International Nuclear Information System (INIS)

    Prudnikov, Y.D.; Shapkina, Y.S.

    1976-01-01

    Chromium, cobalt, and nickel were determined in a flame spectrophotometer with a dual diffraction monochromator, DFS-12, in a high-temperature nitrogen-acetylene flame. The effect of ionization and the elements in the oxidizing flame was small. The lower limit of detection for the three elements is 1x10 -2 to 1 x10 -3 μg/ml, and the high selectivity of the analysis permits determining down to 10 -4 % Cr and Ni and to 10 -3 % Co. These elements may be determined in rocks and minerals from solutions prepared for analysis for alkali and alkali-earth elements. The possibilities of emission flame spectrophotometry are as great as those of atomic-absorption analysis, and it may be used for determining Cr, Co, and Ni in rocks and minerals, especially pure substances, metals, and other materials

  3. Reduction of Nitrogen Oxides using zeolite catalysts exchanged with cobalt

    International Nuclear Information System (INIS)

    Garcia M, E.A.; Bustamante L, F.; Montes de C, C.

    1999-01-01

    The Selective Catalytic Reduction (SCR) of NOx by methane in excess oxygen was studied over several zeolite catalysts; namely cobalt loaded mordenite, ferrierite, SM-5 and the corresponding acid forms. When NO2 predominated n the NOx mixture the acid forms showed the highest N2 formation rates under dry conditions. Mordenite supported catalysts were the most active ones followed by ferrierite and ZSM-5. The most active Co-Mordenite catalyst was tested using a NOx mixture, containing mostly NO, under dry conditions and in the presence of water and SO2. The addition of 8 % water to the reaction mixture lead to a reversible deactivation, mainly at low temperatures. When the reaction mixture contained 60 ppm SO2, the N2 formation rate decreased about a half likely due to SO2 poisoning

  4. Practical and clinical considerations in cobalt-60 tomotherapy

    International Nuclear Information System (INIS)

    Joshi, Chandra P.; Darko, Johnson; Kerr, Andrew; John Schreiner, L.; Dhanesar, Sandeep; Vidyasagar, P.B.

    2008-01-01

    Cobalt-60 ( 60 Co) based therapy established the high energy radiation treatment of cancer in the 1950s but its use declined as cancer centres moved to linear accelerators. 60 Co still has a significant role in developing and newly industrialized countries, where access to radiation therapy is extremely limited. However to gain acceptance, the technology has to be developed to accommodate modern techniques, including image guided and adaptive radiation therapies. At the CCSEO we have established that the development of an adaptive radiation therapy capable 60 Co unit (incorporating complex conformal dose delivery with on-line imaging) is possible. In this presentation we will describe some of the practical and clinical considerations for 60 Co radiation therapy in one particular implementation, tomotherapy i.e. rotational IMRT

  5. Activity distribution of a cobalt-60 teletherapy source

    International Nuclear Information System (INIS)

    Jaffray, D.A.; Munro, P.; Battista, J.J.; Fenster, A.

    1991-01-01

    In the course of quantifying the effect of radiation source size on the spatial resolution of portal images, a concentric ring structure in the activity distribution of a Cobalt-60 teletherapy source has been observed. The activity distribution was measured using a strip integral technique and confirmed independently by a contact radiograph of an identical but inactive source replica. These two techniques suggested that this concentric ring structure is due to the packing configuration of the small 60Co pellets that constitute the source. The source modulation transfer function (MTF) showed that this ring structure has a negligible influence on the spatial resolution of therapy images when compared to the effect of the large size of the 60Co source

  6. Homogeneous Precipitation Synthesis and Magnetic Properties of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zhigang Liu

    2008-01-01

    Full Text Available Magnetic nanoparticles (NPs of cobalt ferrite have been synthesized via a homogeneous precipitation route using hexamethylenetetramine (HMT as the precipitant. The particle size, crystal structure, and magnetic properties of the synthesized particles were investigated by X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The NPs are of cubic inverse spinel structure and nearly spherical shape. With the increase of oxidation time from 30 to 180 minutes in the reaction solution at 90∘C, the average particle size increases from ~30 nm to ~45 nm. The as-synthesized NPs ~30 nm in size show higher Ms (61.5 emu/g and moderate Hc (945 Oe and Mr/Ms (0.45 value compared with the materials synthesized by coprecipitation method using NaOH as precipitate at high pH value.

  7. Cobalt magnetic nanoparticles embedded in carbon matrix: biofunctional validation

    Energy Technology Data Exchange (ETDEWEB)

    Krolow, Matheus Z., E-mail: matheuskrolow@ifsul.edu.br [Universidade Federal de Pelotas, Engenharia de Materiais, Centro de Desenvolvimento Tecnologico (Brazil); Monte, Leonardo G.; Remiao, Mariana H.; Hartleben, Claudia P.; Moreira, Angela N.; Dellagostin, Odir A. [Universidade Federal de Pelotas, Nucleo de Biotecnologia, Centro de Desenvolvimento Tecnologico (Brazil); Piva, Evandro [Universidade Federal de Pelotas, Faculdade de Odontologia (Brazil); Conceicao, Fabricio R. [Universidade Federal de Pelotas, Nucleo de Biotecnologia, Centro de Desenvolvimento Tecnologico (Brazil); Carreno, Neftali L. V. [Universidade Federal de Pelotas, Engenharia de Materiais, Centro de Desenvolvimento Tecnologico (Brazil)

    2012-09-15

    Carbon nanostructures and nanocomposites display versatile allotropic morphologies, physico-chemical properties and have a wide range of applications in mechanics, electronics, biotechnology, structural material, chemical processing, and energy management. In this study we report the synthesis, characterization, and biotechnological application of cobalt magnetic nanoparticles, with diameter approximately 15-40 nm, embedded in carbon structure (Co/C-MN). A single-step chemical process was used in the synthesis of the Co/C-MN. The Co/C-MN has presented superparamagnetic behavior at room temperature an essential property for immunoseparation assays carried out here. To stimulate interactions between proteins and Co/C-MN, this nanocomposite was functionalized with acrylic acid (AA). We have showed the bonding of different proteins onto Co/C-AA surface using immunofluorescence assay. A Co/C-AA coated with monoclonal antibody anti-pathogenic Leptospira spp. was able to capture leptospires, suggesting that it could be useful in immunoseparation assays.

  8. Cobalt magnetic nanoparticles embedded in carbon matrix: biofunctional validation

    International Nuclear Information System (INIS)

    Krolow, Matheus Z.; Monte, Leonardo G.; Remião, Mariana H.; Hartleben, Cláudia P.; Moreira, Ângela N.; Dellagostin, Odir A.; Piva, Evandro; Conceição, Fabricio R.; Carreño, Neftalí L. V.

    2012-01-01

    Carbon nanostructures and nanocomposites display versatile allotropic morphologies, physico-chemical properties and have a wide range of applications in mechanics, electronics, biotechnology, structural material, chemical processing, and energy management. In this study we report the synthesis, characterization, and biotechnological application of cobalt magnetic nanoparticles, with diameter approximately 15–40 nm, embedded in carbon structure (Co/C-MN). A single-step chemical process was used in the synthesis of the Co/C-MN. The Co/C-MN has presented superparamagnetic behavior at room temperature an essential property for immunoseparation assays carried out here. To stimulate interactions between proteins and Co/C-MN, this nanocomposite was functionalized with acrylic acid (AA). We have showed the bonding of different proteins onto Co/C-AA surface using immunofluorescence assay. A Co/C-AA coated with monoclonal antibody anti-pathogenic Leptospira spp. was able to capture leptospires, suggesting that it could be useful in immunoseparation assays.

  9. Tetraaquabis[2-(2-nitrophenylacetato-κO]cobalt(II

    Directory of Open Access Journals (Sweden)

    Muhammad Danish

    2015-03-01

    Full Text Available The molecule of the title compound, [Co(C8H6NO42(H2O4], is centrosymmetric. It is a cobalt(II complex, bearing two (2-nitrophenylacetate and four aqua ligands. The coordination around the CoII atom is distorted octahedral, defined by four O atoms of water molecules in the equatorial plane and by two carboxylate O atoms at axial positions. The dihedral angles between the benzene ring and the acetate and nitro groups are 61.90 (10 and 19.21 (11°, respectively. The water molecules form O—H...O hydrogen bonds with the nitro and carboxylate groups, leading to a layered structural arrangement parallel to (001.

  10. Microwave non-resonant absorption in fine cobalt ferrite particles

    International Nuclear Information System (INIS)

    Mata-Zamora, M.E.; Montiel, H.; Alvarez, G.; Saniger, J.M.; Zamorano, R.; Valenzuela, R.

    2007-01-01

    Cobalt ferrite particles of average crystallite size of 11 nm were obtained by a sol-gel process at 400 deg. C . The powders were annealed at temperatures of 500, 600, 700 and 800 deg. C in air. Derivative microwave power absorption (dP/dH) measurements were carried out as a function of magnetic field (H DC ) at X band (9.4 GHz), in the field range -80-796 kA/m for all annealed temperatures. In order to compare the response of saturation magnetization measurements with high frequency measurements, we calculated the areas inside both the magnetization (A M ) and the absorption hysteresis loops (A LFS ). The dependence of these areas as a function of crystallite size is remarkably similar in both experiments

  11. Four-electron oxygen reduction by brominated cobalt corrole.

    Science.gov (United States)

    Schechter, Alex; Stanevsky, Maria; Mahammed, Atif; Gross, Zeev

    2012-01-02

    The carbon-supported cobalt(III) complex of β-pyrrole-brominated 5,10,15-tris(pentafluorophenyl)corrole [Co(tpfc)Br(8)/C] is introduced as a nonplatinum alternative for electrocatalytic oxygen reduction in aqueous solutions. Through systematic work, the basic kinetic parameters of this reaction were studied, using rotating ring disk electrode electrochemical methods in the pH range of 0-11. Pronounced catalytic activity was detected in acid solutions along with shifts of the Co(II)/Co(III) and O(2) redox couples to more positive values (onset of 0.56 V at pH 0). A series of independent measurements have been used to prove that the dominant mechanism for oxygen reduction by Co(tpfc)Br(8)/C catalysis is the direct four-electron pathway to water.

  12. Magnetic properties engineering of nanopatterned cobalt antidot arrays

    International Nuclear Information System (INIS)

    Kaidatzis, Andreas; Niarchos, Dimitrios; Del Real, Rafael P; Vázquez, Manuel; Alvaro, Raquel; Anguita, José; García-Martín, José Miguel; Luis Palma, Juan; Escrig, Juan

    2016-01-01

    We report on the study of arrays of 60 nm wide cobalt antidots, nanopatterned using focused ion beam milling. Square and hexagonal symmetry arrays have been studied, with varying antidot densities and lattice constant from 150 up to 300 nm. We find a strong increase of the arrays’ magnetic coercivity with respect to the unpatterned film, which is monotonic as the antidot density increases. Additionally, there is a strong influence of the array symmetry to the in-plane magnetic anisotropy: square arrays exhibit fourfold symmetry and hexagonal arrays exhibit sixfold symmetry. The above findings are corroborated by magnetic imaging and micromagnetic modeling, which show the magnetic structure of the arrays to depend strongly on the array morphology. (paper)

  13. Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst.

    Science.gov (United States)

    Korstanje, Ties J; van der Vlugt, Jarl Ivar; Elsevier, Cornelis J; de Bruin, Bas

    2015-10-16

    The reduction of esters and carboxylic acids to alcohols is a highly relevant conversion for the pharmaceutical and fine-chemical industries and for biomass conversion. It is commonly performed using stoichiometric reagents, and the catalytic hydrogenation of the acids previously required precious metals. Here we report the homogeneously catalyzed hydrogenation of carboxylic acids to alcohols using earth-abundant cobalt. This system, which pairs Co(BF4)2·6H2O with a tridentate phosphine ligand, can reduce a wide range of esters and carboxylic acids under relatively mild conditions (100°C, 80 bar H2) and reaches turnover numbers of up to 8000. Copyright © 2015, American Association for the Advancement of Science.

  14. An evaluated neutronic data file for elemental cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, P.; Lawson, R.; Meadows, J.; Sugimoto, M.; Smith, A.; Smith, D.; Howerton, R.

    1988-08-01

    A comprehensive evaluated neutronic data file for elemental cobalt is described. The experimental data base, the calculational methods, the evaluation techniques and judgments, and the physical content are outlined. The file contains: neutron total and scattering cross sections and associated properties, (n,2n) and (n,3n) processes, neutron radiative capture processes, charged-particle-emission processes, and photon-production processes. The file extends from 10/sup /minus/5/ eV to 20 MeV, and is presented in the ENDF/B-VI format. Detailed attention is given to the uncertainties and correlations associated with the prominent neutron-induced processes. The numerical contents of the file have been transmitted to the National Nuclear Data Center, Brookhaven National Laboratory. 143 refs., 16 figs., 5 tabs.

  15. Size-dependent antimicrobial properties of the cobalt ferrite nanoparticles

    International Nuclear Information System (INIS)

    Žalnėravičius, Rokas; Paškevičius, Algimantas; Kurtinaitiene, Marija; Jagminas, Arūnas

    2016-01-01

    The growing resistance of bacteria to conventional antibiotics elicited considerable interest to non-typical drugs. In this study, antimicrobial investigations were performed on low-size dispersion cobalt ferrite nanoparticles (Nps) fabricated by co-precipitation approach in several average sizes, in particular, 15.0, 5.0, and 1.65 nm. A variety of experimental tests demonstrated that the size of these Nps is determinant for antimicrobial efficiency against S. cerevisiae and several Candida species, in particular, C. parapsilosis, C. krusei, and C. albicans. The small and ultra-small fractions of CoFe 2 O 4 Nps possess especially strong antimicrobial activity against all tested microorganisms. The possible reasons are discussed. Nps were characterized by means of transmission and high-resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and atomic force microscopy, chemical analysis and magnetic measurements.Graphical Abstract

  16. Size-dependent antimicrobial properties of the cobalt ferrite nanoparticles

    Science.gov (United States)

    Žalnėravičius, Rokas; Paškevičius, Algimantas; Kurtinaitiene, Marija; Jagminas, Arūnas

    2016-10-01

    The growing resistance of bacteria to conventional antibiotics elicited considerable interest to non-typical drugs. In this study, antimicrobial investigations were performed on low-size dispersion cobalt ferrite nanoparticles (Nps) fabricated by co-precipitation approach in several average sizes, in particular, 15.0, 5.0, and 1.65 nm. A variety of experimental tests demonstrated that the size of these Nps is determinant for antimicrobial efficiency against S. cerevisiae and several Candida species, in particular, C. parapsilosis, C. krusei, and C. albicans. The small and ultra-small fractions of CoFe2O4 Nps possess especially strong antimicrobial activity against all tested microorganisms. The possible reasons are discussed. Nps were characterized by means of transmission and high-resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and atomic force microscopy, chemical analysis and magnetic measurements.

  17. Systemic cobalt toxicity from total hip arthroplasties: review of a rare condition Part 1 - history, mechanism, measurements, and pathophysiology.

    Science.gov (United States)

    Cheung, A C; Banerjee, S; Cherian, J J; Wong, F; Butany, J; Gilbert, C; Overgaard, C; Syed, K; Zywiel, M G; Jacobs, J J; Mont, M A

    2016-01-01

    Recently, the use of metal-on-metal articulations in total hip arthroplasty (THA) has led to an increase in adverse events owing to local soft-tissue reactions from metal ions and wear debris. While the majority of these implants perform well, it has been increasingly recognised that a small proportion of patients may develop complications secondary to systemic cobalt toxicity when these implants fail. However, distinguishing true toxicity from benign elevations in cobalt ion levels can be challenging. The purpose of this two part series is to review the use of cobalt alloys in THA and to highlight the following related topics of interest: mechanisms of cobalt ion release and their measurement, definitions of pathological cobalt ion levels, and the pathophysiology, risk factors and treatment of cobalt toxicity. Historically, these metal-on-metal arthroplasties are composed of a chromium-cobalt articulation. The release of cobalt is due to the mechanical and oxidative stresses placed on the prosthetic joint. It exerts its pathological effects through direct cellular toxicity. This manuscript will highlight the pathophysiology of cobalt toxicity in patients with metal-on-metal hip arthroplasties. Patients with new or evolving hip symptoms with a prior history of THA warrant orthopaedic surgical evaluation. Increased awareness of the range of systemic symptoms associated with cobalt toxicity, coupled with prompt orthopaedic intervention, may forestall the development of further complications. ©2016 The British Editorial Society of Bone & Joint Surgery.

  18. Snapshot of cobalt, chromium and nickel exposure in dental technicians.

    Science.gov (United States)

    Kettelarij, Jolinde; Nilsson, Sara; Midander, Klara; Lidén, Carola; Julander, Anneli

    2016-12-01

    It is not fully understood where and how people are exposed to sensitizing metals. Much can be learnt from studying occupational settings where metals are handled. To quantify cobalt (Co), chromium (Cr) and nickel (Ni) exposure on the skin and in the air, and urine levels, in dental technicians working with tools and alloys that may result in skin and respiratory exposure. The metal skin dose was quantified with acid wipe sampling in dental technicians (n = 13). Air exposure was monitored by personal air sampling. Spot urine samples were collected for 24 h. Metals were analysed with inductively coupled plasma mass spectrometry. Before work, Co was detected on the skin of 10 participants (0.00025-0.0039 µg/cm 2 ), and Cr (0.00051-0.011 µg/cm 2 ) and Ni (0.0062-0.15 µg/cm 2 ) on the skin of all participants. After a 2-h period without hand washing, CoCr-exposed participants had more Co on the skin (p = 0.004) than non-CoCr-exposed participants. Co was found in 10 air samples (0.22-155 µg/m 3 ), Cr in nine (0.43-71 µg/m 3 ), and Ni in four (0.48-3.7 µg/m 3 ). Metal urine concentrations were considered to be normal. Dental technicians were exposed to Co, Cr and Ni on the skin and through the air, which was not reflected in the urine concentrations in this study. Cobalt skin doses may potentially elicit allergic contact dermatitis and cause sensitization. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Monte Carlo study of MLC fields for cobalt therapy machine

    Directory of Open Access Journals (Sweden)

    Komanduri M Ayyangar

    2014-01-01

    Full Text Available An automated Multi-Leaf Collimator (MLC system has been developed as add-on for the cobalt-60 teletherapy machines available in India. The goal of the present computational study is to validate the MLC design using Monte Carlo (MC modeling. The study was based on the Kirloskar-supplied Phoenix model machines that closely match the Atomic Energy of Canada Limited (AECL theratron-80 machine. The MLC is a retrofit attachment to the collimator assembly, with 14 non-divergent leaf pairs of 40 mm thick, 7 mm wide, and 150 mm long tungsten alloy plates with rounded edges and 20 mm tongue and 2 mm groove in each leaf. In the present work, the source and collimator geometry has been investigated in detail to arrive at a model that best represents the measured dosimetric data. The authors have studied in detail the proto-I MLC built for cobalt-60. The MLC field sizes were MC simulated for 2 × 2 cm 2 to 14 × 14 cm 2 square fields as well as irregular fields, and the percent depth dose (PDD and profile data were compared with ROPS† treatment planning system (TPS. In addition, measured profiles using the IMATRIXX system‡ were also compared with the MC simulations. The proto-I MLC can define radiation fields up to 14 × 14 cm΂ within 3 mm accuracy. The maximum measured leakage through the leaf ends in closed condition was 3.4% and interleaf leakage observed was 7.3%. Good agreement between MC results, ROPS and IMATRIXX results has been observed. The investigation also supports the hypothesis that optical and radiation field coincidence exists for the square fields studied with the MLC. Plots of the percent depth dose (PDD data and profile data for clinically significant irregular fields have also been presented. The MC model was also investigated to speed up the calculations to allow calculations of clinically relevant conformal beams.

  20. Magnetization and anisotropy of cobalt ferrite thin films

    Science.gov (United States)

    Eskandari, F.; Porter, S. B.; Venkatesan, M.; Kameli, P.; Rode, K.; Coey, J. M. D.

    2017-12-01

    The magnetization of thin films of cobalt ferrite frequently falls far below the bulk value of 455 kA m-1 , which corresponds to an inverse cation distribution in the spinel structure with a significant orbital moment of about 0.6 μB that is associated with the octahedrally coordinated Co2+ ions. The orbital moment is responsible for the magnetostriction and magnetocrystalline anisotropy and its sensitivity to imposed strain. We have systematically investigated the structure and magnetism of films produced by pulsed-laser deposition on different substrates (Ti O2 , MgO, MgA l2O4 , SrTi O3 , LSAT, LaAl O3 ) and as a function of temperature (500 -700 °C) and oxygen pressure (10-4-10 Pa ) . Magnetization at room-temperature ranges from 60 to 440 kA m-1 , and uniaxial substrate-induced anisotropy ranges from +220 kJ m-3 for films on deposited on MgO (100) to -2100 kJ m-3 for films deposited on MgA l2O4 (100), where the room-temperature anisotropy field reaches 14 T. No rearrangement of high-spin Fe3+ and Co2+ cations on tetrahedral and octahedral sites can reduce the magnetization below the bulk value, but a switch from Fe3+ and Co2+ to Fe2+ and low-spin Co3+ on octahedral sites will reduce the low-temperature magnetization to 120 kA m-1 , and a consequent reduction of Curie temperature can bring the room-temperature value to near zero. Possible reasons for the appearance of low-spin cobalt in the thin films are discussed.