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Sample records for plasmid-induced cobalt limitation

  1. Metabolite profiling uncovers plasmid-induced cobalt limitation under methylotrophic growth conditions.

    Directory of Open Access Journals (Sweden)

    Patrick Kiefer

    Full Text Available BACKGROUND: The introduction and maintenance of plasmids in cells is often associated with a reduction of growth rate. The reason for this growth reduction is unclear in many cases. METHODOLOGY/PRINCIPAL FINDINGS: We observed a surprisingly large reduction in growth rate of about 50% of Methylobacterium extorquens AM1 during methylotrophic growth in the presence of a plasmid, pCM80 expressing the tetA gene, relative to the wild-type. A less pronounced growth delay during growth under non-methylotrophic growth conditions was observed; this suggested an inhibition of one-carbon metabolism rather than a general growth inhibition or metabolic burden. Metabolome analyses revealed an increase in pool sizes of ethylmalonyl-CoA and methylmalonyl-CoA of more than 6- and 35-fold, respectively, relative to wild type, suggesting a strongly reduced conversion of these central intermediates, which are essential for glyoxylate regeneration in this model methylotroph. Similar results were found for M. extorquens AM1 pCM160 which confers kanamycin resistance. These intermediates of the ethylmalonyl-CoA pathway have in common their conversion by coenzyme B(12-dependent mutases, which have cobalt as a central ligand. The one-carbon metabolism-related growth delay was restored by providing higher cobalt concentrations, by heterologous expression of isocitrate lyase as an alternative path for glyoxylate regeneration, or by identification and overproduction of proteins involved in cobalt import. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that the introduction of the plasmids leads to an apparent inhibition of the cobalt-dependent enzymes of the ethylmalonyl-CoA pathway. Possible explanations are presented and point to a limited cobalt concentration in the cell as a consequence of the antibiotic stress.

  2. Cobalt.

    Science.gov (United States)

    Fowler, Joseph F

    2016-01-01

    Cobalt has been a recognized allergen capable of causing contact dermatitis for decades. Why, therefore, has it been named 2016 "Allergen of the Year"? Simply put, new information has come to light in the last few years regarding potential sources of exposure to this metallic substance. In addition to reviewing some background on our previous understanding of cobalt exposures, this article will highlight the recently recognized need to consider leather as a major site of cobalt and the visual cues suggesting the presence of cobalt in jewelry. In addition, a chemical spot test for cobalt now allows us to better identify its presence in suspect materials.

  3. Structural, thermal and dielectric properties of cobaltous malonate single crystals grown in limited diffusion media

    Energy Technology Data Exchange (ETDEWEB)

    Lincy, A.; Mahalakshmi, V.; Tinto, A.J.; Thomas, J. [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College, Changanassery 686101, Kerala (India); Saban, K.V., E-mail: smartlabindia@gmail.co [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College, Changanassery 686101, Kerala (India)

    2010-11-15

    Well-faceted crystals of cobaltous malonate (C{sub 6} H{sub 12} Co{sub 2} O{sub 12}) have been grown by the controlled diffusion of ionic species in hydrosilica gel. Single crystal X-ray diffraction studies show that the crystal belongs to the monoclinic system with space group C2/m. The unit cell dimensions are a=12.6301(9) A, b=7.3857(9) A, c=7.2945(7) A, {alpha}={gamma}=90{sup o}, {beta}=120.193(9){sup o}. The functional groups, elucidated from the FT-IR spectrum, are in conformity with the information derived from the X-ray diffraction studies. The thermal behaviour of the material has been investigated using TG-DTA in the temperature range 30-1050 deg. C. The optical band gap of the sample is estimated using diffuse reflectance spectroscopy (DRS). The dielectric constant and dielectric loss of the crystal have been studied over wide temperature and frequency ranges. AC conductivity measurements reveal a thermally activated process and the mechanism behind the conduction process has been discussed.

  4. Overcoming the Limitations of C-H Activation with Strongly Coordinating N-Heterocycles by Cobalt Catalysis.

    Science.gov (United States)

    Wang, Hui; Lorion, Mélanie M; Ackermann, Lutz

    2016-08-22

    Strongly coordinating nitrogen heterocycles, including pyrimidines, oxazolines, pyrazoles, and pyridines, were fully tolerated in cobalt-catalyzed C-H amidations by imidate assistance. Structurally complex quinazolines are thus accessible in a step-economic manner. Our findings also establish the relative powers of directing groups in cobalt(III)-catalyzed C-H functionalization for the first time.

  5. Cobalt poisoning

    Science.gov (United States)

    ... against the metal cup when you walk. These metal particles (ions) can get released into the hip socket and ... Cobalt may also be found in: Alloys Batteries Chemistry/crystal ... Magnets Some metal-on-metal hip implants Tires Cobalt was once ...

  6. Limits on the use of cobalt sulfide as anode of p-type dye-sensitized solar cells

    Science.gov (United States)

    Bonomo, Matteo; Congiu, Mirko; De Marco, Maria Letizia; Dowling, Denis P.; Di Carlo, Aldo; Graeff, Carlos F. O.; Dini, Danilo

    2017-06-01

    Thin films of cobalt sulfide (CoS) of thickness l  traditional platinized fluorine-doped indium oxide (Pt-FTO) due to the lower cost of the starting materials (Co salts) and the easier procedure of deposition onto large area substrates. The latter process was carried out via direct precipitation of CoS from aqueous solutions. The photoconversion efficiency (η) of the corresponding device was 0.07%. This value is about 35% less than the efficiency that is obtained with the analogous p-DSC employing the Pt-FTO anode (η  =  0.11). Unlike p-DSCs based on Pt-FTO anodes, the photoelectrochemical cells employing CoS electrodes showed that this anodic material was not able to sustain the photocurrent densities generated by P1-sensitized NiO at a given photopotential. Illumination of the p-DSCs with CoS anodes and P1-sensitized NiO cathodes actually induced the reverse bias of the photoelectrochemical cell with CoS behaving like a p-type semiconductor with no degeneracy. Dedicated to Professor Roberto Federici on the occasion of his retirement.

  7. Radiochemical separation of Cobalt

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    A method is described for the radiochemical separation of cobalt based on the extraordinary stability of cobalt diethyldithiocarbamate. Interferences are few; only very small amounts of zinc and iron accompany cobalt, which is important in neutron-activation analysis.

  8. Radiochemical separation of Cobalt

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    A method is described for the radiochemical separation of cobalt based on the extraordinary stability of cobalt diethyldithiocarbamate. Interferences are few; only very small amounts of zinc and iron accompany cobalt, which is important in neutron-activation analysis.

  9. 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....

  10. Cobalt release from inexpensive jewellery

    DEFF Research Database (Denmark)

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

    2010-01-01

    Objectives: 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. Methods: 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). 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....... 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...

  11. Effect of cobalt on the Anaerobic Thermophilic Conversion of Methanol

    NARCIS (Netherlands)

    Paulo, P.L.; Jiang, B.; Cysneiros, D.; Stams, A.J.M.

    2004-01-01

    The importance of cobalt on the anaerobic conversion of methanol under thermophilic conditions was studied in three parallel lab-scale UASB-reactors and in cobalt-limited enriched cultures. Reactors R1, R2, and R3 were fed with methanol in a bicarbonate-buffered medium, supplied with iron and

  12. Cobalt exposure in a carbide tip grinding process.

    Science.gov (United States)

    Stebbins, A I; Horstman, S W; Daniell, W E; Atallah, R

    1992-03-01

    Reports relating hard metal disease or nonspecific respiratory symptoms to tungsten or cobalt exposure have been published in the past 20 yr. This report discusses a work site investigation of a small company, employing approximately 50 workers, producing carbide tip saw blades for the woodworking industry. Cobalt exposure was characterized by ambient air monitoring (area and personnel), particle size determination, and biological monitoring. Area sampling for cadmium, cobalt, and tungsten indicated low ambient air levels in all manufacturing areas except the grinding department, which had cobalt air levels approaching the threshold limit value of 0.05 mg/m3. Area airborne cobalt exposure levels measured over six shifts in the grinding department ranged from 0.017 to 0.12 mg/m3 for the total collection method and 0.002 to 0.028 mg/m3 for the method collecting respirable particles. Cobalt content in the total and respirable fractions was similar. Urine monitoring indicated production workers have elevated cobalt levels, and the grinders' levels were higher than other production workers. The grinding coolant was found to have elevated cobalt concentrations. A survey of coolants from nine carbide grinding shops indicated the elevated cobalt concentrations may be common.

  13. A dissolved cobalt plume in the oxygen minimum zone of the eastern tropical South Pacific

    Science.gov (United States)

    Hawco, Nicholas J.; Ohnemus, Daniel C.; Resing, Joseph A.; Twining, Benjamin S.; Saito, Mak A.

    2016-10-01

    Cobalt is a nutrient to phytoplankton, but knowledge about its biogeochemical cycling is limited, especially in the Pacific Ocean. Here, we report sections of dissolved cobalt and labile dissolved cobalt from the US GEOTRACES GP16 transect in the South Pacific. The cobalt distribution is closely tied to the extent and intensity of the oxygen minimum zone in the eastern South Pacific with highest concentrations measured at the oxycline near the Peru margin. Below 200 m, remineralization and circulation produce an inverse relationship between cobalt and dissolved oxygen that extends throughout the basin. Within the oxygen minimum zone, elevated concentrations of labile cobalt are generated by input from coastal sources and reduced scavenging at low O2. As these high cobalt waters are upwelled and advected offshore, phytoplankton export returns cobalt to low-oxygen water masses underneath. West of the Peru upwelling region, dissolved cobalt is less than 10 pM in the euphotic zone and strongly bound by organic ligands. Because the cobalt nutricline within the South Pacific gyre is deeper than in oligotrophic regions in the North and South Atlantic, cobalt involved in sustaining phytoplankton productivity in the gyre is heavily recycled and ultimately arrives from lateral transport of upwelled waters from the eastern margin. In contrast to large coastal inputs, atmospheric deposition and hydrothermal vents along the East Pacific Rise appear to be minor sources of cobalt. Overall, these results demonstrate that oxygen biogeochemistry exerts a strong influence on cobalt cycling.

  14. Limiter

    Science.gov (United States)

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  15. Electrodeposition of Cobalt Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sungbok; Hong, Kimin [Chungnam National Univ., Daejeon (Korea, Republic of)

    2013-03-15

    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{sub 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{sup 2} and DAESA concentration was 1 mL/L.

  16. 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.)

  17. 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

    phase lasting several weeks, and with a significant long-term retention in tissues for several years. In serum cobalt (Co{sup 2+}) binds to albumin, and the concentration of free, ionized Co{sup 2+} is estimated at 5-12% of the total cobalt concentration. In human red cells the membrane transport pathway for cobalt (Co{sup 2+}) uptake appears to be shared with calcium (Ca{sup 2+}), but with the uptake being essentially irreversible as cobalt is effectively bound in the cytosol and is not itself extruded by the Ca-pump. It is tempting to speculate that this could perhaps also be the case in other animal cells. If this were actually the case, the tissue partitioning and biokinetics of cobalt in cells and tissues would be closely related to the uptake of calcium, with cobalt partitioning primarily into tissues with a high calcium turn-over, and with cobalt accumulation and retention in tissues with a slow turn-over of the cells. The occupational cobalt exposure, e.g. in cobalt processing plants and hard-metal industry is well known and has probably been somewhat reduced in more recent years due to improved work place hygiene. Of note, however, adverse reactions to heart and lung have recently been demonstrated following cobalt exposure near or slightly under the current occupational exposure limit. Over the last decades the use of cobalt-chromium hard-metal alloys in orthopedic joint replacements, in particular in metal-on-metal bearings in hip joint arthroplasty, has created an entirely new source of internal cobalt exposure. Corrosion and wear produce soluble metal ions and metal debris in the form of huge numbers of wear particles in nanometric size, with systemic dissemination through lymph and systemic vascular system. This may cause adverse local reactions in peri-prosthetic soft-tissues, and in addition systemic toxicity. Of note, the metal nanoparticles have been demonstrated to be clearly more toxic than larger, micrometer-sized particles, and this has made the

  18. Cobalt metabolism and toxicology--a brief update.

    Science.gov (United States)

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

    2012-08-15

    , and with a significant long-term retention in tissues for several years. In serum cobalt (Co(2+)) binds to albumin, and the concentration of free, ionized Co(2+) is estimated at 5-12% of the total cobalt concentration. In human red cells the membrane transport pathway for cobalt (Co(2+)) uptake appears to be shared with calcium (Ca(2+)), but with the uptake being essentially irreversible as cobalt is effectively bound in the cytosol and is not itself extruded by the Ca-pump. It is tempting to speculate that this could perhaps also be the case in other animal cells. If this were actually the case, the tissue partitioning and biokinetics of cobalt in cells and tissues would be closely related to the uptake of calcium, with cobalt partitioning primarily into tissues with a high calcium turn-over, and with cobalt accumulation and retention in tissues with a slow turn-over of the cells. The occupational cobalt exposure, e.g. in cobalt processing plants and hard-metal industry is well known and has probably been somewhat reduced in more recent years due to improved work place hygiene. Of note, however, adverse reactions to heart and lung have recently been demonstrated following cobalt exposure near or slightly under the current occupational exposure limit. Over the last decades the use of cobalt-chromium hard-metal alloys in orthopedic joint replacements, in particular in metal-on-metal bearings in hip joint arthroplasty, has created an entirely new source of internal cobalt exposure. Corrosion and wear produce soluble metal ions and metal debris in the form of huge numbers of wear particles in nanometric size, with systemic dissemination through lymph and systemic vascular system. This may cause adverse local reactions in peri-prosthetic soft-tissues, and in addition systemic toxicity. Of note, the metal nanoparticles have been demonstrated to be clearly more toxic than larger, micrometer-sized particles, and this has made the concept of nanotoxicology a crucial, new

  19. 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.

  20. 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 w

  1. 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

  2. Halogenation of cobalt dicarbollide

    Science.gov (United States)

    Hurlburt, Paul K.; Abney, Kent D.; Kinkead, Scott A.

    1997-01-01

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10' positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron.

  3. 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' – ... temperature and coordinated water were determined ... indicating fairly stable complex compounds (Table 1). The complex compounds are insoluble [Table 2] in water and common organic solvents, but are readily soluble in ...

  4. 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...

  5. Cobalt sorption in silica-pillared clays.

    Science.gov (United States)

    Sampieri, A; Fetter, G; Bosch, P; Bulbulian, S

    2006-01-03

    Silicon pillared samples were prepared following conventional and microwave irradiation methods. The samples were characterized and tested in cobalt sorption. Ethylenediammine was added before cobalt addition to improve the amount of cobalt retained. The amount of cobalt introduced in the original clay in the presence of ethylenediammine was the highest. In calcined pillared clays the cobalt retention with ethylenediammine was lower (ca. 40%). In all cases the presence of ethylenediammine increased twice the amount of cobalt sorption measured for aqueous solutions.

  6. Bioaccessibility testing of cobalt compounds.

    Science.gov (United States)

    Stopford, Woodhall; Turner, John; Cappellini, Danielle; Brock, Tom

    2003-08-01

    Testing of metal compounds for solubility in artificial fluids has been used for many years to assist determining human health risk from exposure to specific compounds of concern. In lieu of obtaining bioavailability data from samples of urine, blood, or other tissues, these studies measured solubility of compounds in various artificial fluids as a surrogate for bioavailability. In this context, the measurement of metal "bioaccessibility" can be used as an in vitro substitute for measuring metal bioavailability. Bioaccessibility can be defined as a value representing the availability of metal for absorption when dissolved in in vitro surrogates of body fluids or juices. The aim of this study was to measure and compare the bioaccessibility of selected cobalt compounds in artificial human tissue fluids and human serum. A second aim was to initiate studies to experimentally validate an in vitro methodology that would provide a conservative estimate of cobalt bioavailability in the assessment of dose from human exposure to various species of cobalt compounds. This study evaluated the bioaccessibility of cobalt(II) from 11 selected cobalt compounds and an alloy in 2 physical forms in 5 surrogate human tissue fluids and human serum. Four (4) separate extraction times were used up to 72 hours. The effect of variables such as pH, dissolution time, and mass-ion effect on cobalt bioaccessibility were assessed as well. We found that the species of cobalt compound as well as the physico-chemical properties of the surrogate fluids, especially pH, had a major impact on cobalt solubility. Cobalt salts such as cobalt(II) sulfate heptahydrate were highly soluble, whereas cobalt alloys used in medical implants and cobalt aluminate spinels used as pigments, showed minimal dissolution over the period of the assay.

  7. Cobalt ion-containing epoxies

    Science.gov (United States)

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

    1983-01-01

    Varying concentrations of an organometallic cobalt complex were added to an epoxy system currently used by the aerospace industry as a composite matrix resin. Methods for combining cobalt (III) acetylacetonate with a tetraglycidyl 4,4 prime - diaminodiphenylmethane-based epoxy were investigated. The effects of increasing cobalt ion concentration on the epoxy cure were demonstrated by epoxy gel times and differential scanning calorimetry cure exotherms. Analysis on cured cobalt-containing epoxy castings included determination of glass transition temperatures by thermomechanical analysis, thermooxidative stabilities by thermogravimetric analysis, and densities in a density gradient column. Flexural strength and stiffness were also measured on the neat resin castings.

  8. Blood doping by cobalt. Should we measure cobalt in athletes?

    Directory of Open Access Journals (Sweden)

    Guidi Gian

    2006-07-01

    Full Text Available Abstract Background Blood doping is commonplace in competitive athletes who seek to enhance their aerobic performances through illicit techniques. Presentation of the hypothesis Cobalt, a naturally-occurring element with properties similar to those of iron and nickel, induces a marked and stable polycythemic response through a more efficient transcription of the erythropoietin gene. Testing the hypothesis Although little information is available so far on cobalt metabolism, reference value ranges or supplementation in athletes, there is emerging evidence that cobalt is used as a supplement and increased serum concentrations are occasionally observed in athletes. Therefore, given the athlete's connatural inclination to experiment with innovative, unfair and potentially unhealthy doping techniques, cobalt administration might soon become the most suited complement or surrogate for erythropoiesis-stimulating substances. Nevertheless, cobalt administration is not free from unsafe consequences, which involve toxic effects on heart, liver, kidney, thyroid and cancer promotion. Implications of the hypothesis Cobalt is easily purchasable, inexpensive and not currently comprehended within the World Anti-Doping Agency prohibited list. Moreover, available techniques for measuring whole blood, serum, plasma or urinary cobalt involve analytic approaches which are currently not practical for antidoping laboratories. Thus more research on cobalt metabolism in athletes is compelling, along with implementation of effective strategies to unmask this potentially deleterious doping practice

  9. 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.

  10. 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.

  11. Cobalt source calibration

    Energy Technology Data Exchange (ETDEWEB)

    Rizvi, H.M.

    1999-12-03

    The data obtained from these tests determine the dose rate of the two cobalt sources in SRTC. Building 774-A houses one of these sources while the other resides in room C-067 of Building 773-A. The data from this experiment shows the following: (1) The dose rate of the No.2 cobalt source in Building 774-A measured 1.073 x 10{sup 5} rad/h (June 17, 1999). The dose rate of the Shepherd Model 109 Gamma cobalt source in Building 773-A measured 9.27 x 10{sup 5} rad/h (June 25, 1999). These rates come from placing the graduated cylinder containing the dosimeter solution in the center of the irradiation chamber. (2) Two calibration tests in the 774-A source placed the graduated cylinder with the dosimeter solution approximately 1.5 inches off center in the axial direction. This movement of the sample reduced the measured dose rate 0.92% from 1.083 x 10{sup 5} rad/h to 1.073 x 10{sup 5} rad/h. and (3) A similar test in the cobalt source in 773-A placed the graduated cylinder approximately 2.0 inches off center in the axial direction. This change in position reduced the measured dose rate by 10.34% from 1.036 x 10{sup 6} to 9.27 x 10{sup 5}. This testing used chemical dosimetry to measure the dose rate of a radioactive source. In this method, one determines the dose by the chemical change that takes place in the dosimeter. For this calibration experiment, the author used a Fricke (ferrous ammonium sulfate) dosimeter. This solution works well for dose rates to 10{sup 7} rad/h. During irradiation of the Fricke dosimeter solution the Fe{sup 2+} ions ionize to Fe{sup 3+}. When this occurs, the solution acquires a slightly darker tint (not visible to the human eye). To determine the magnitude of the change in Fe ions, one places the solution in an UV-VIS Spectrophotometer. The UV-VIS Spectrophotometer measures the absorbency of the solution. Dividing the absorbency by the total time (in minutes) of exposure yields the dose rate.

  12. 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.

  13. Recycling cobalt from spent lithium ion battery

    Institute of Scientific and Technical Information of China (English)

    Zhi-dong XIA; Xiao-qian XIE; Yao-wu SHI; Yong-ping LEI; Fu GUO

    2008-01-01

    Spent lithium ion battery is a useful resource of cobalt. In this paper, cobalt was recovered by a chemical process based upon the analysis of the structure and com-position of the lithium ion battery. X-ray diffraction results show that cobalt oxalate and cobaltous sulfate have been obtained in two different processes. Compared with the cobaltous oxalate process, the cobaltous sulfate process was characterized by less chemical substance input and a cobalt recovery rate of as much as 88%. A combination of these two processes in the recycling industry may win in the aspects of compact process and high recovery rate.

  14. 40 CFR 415.653 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Science.gov (United States)

    2010-07-01

    ... CATEGORY Cobalt Salts Production Subcategory § 415.653 Effluent limitations guidelines representing the... limitations for cobalt (T), copper (T), and nickel (T), are the same as specified in § 415.652....

  15. Cobalt monolayer islands on Ag(111) for ORR catalysis.

    Science.gov (United States)

    Loglio, Francesca; Lastraioli, Elisa; Bianchini, Claudio; Fontanesi, Claudio; Innocenti, Massimo; Lavacchi, Alessandro; Vizza, Francesco; Foresti, Maria Luisa

    2011-08-22

    The design of a catalyst for one of the most important electrocatalytic reactions, the oxygen reduction reaction (ORR), was done following the most recent guidelines of theoretical studies on this topic. Aim of this work was to achieve a synergic effect of two different metals acting on different steps of the ORR. The catalytic activity of Ag, already known and characterized, was enhanced by the presence of a monolayer of cobalt subdivided into nanosized islands. To obtain such a controlled nanostructure, a novel method utilizing self-assembled monolayers (SAMs) as templates was employed. In a recent study, we were able to perform a confined electrodeposition of cobalt onto Ag(111) in a template formed by selectively desorbing a short-chain thiol (3-mercaptopropionic acid, MPA) from binary SAMs using 1-dodecanthiols (DDT). This method allows for an excellent control of the morphology of the deposit by varying the molar ratio of the two thiols. Because cobalt does not deposit on silver at an underpotential, the alternative approach of surface limited redox replacement (SLRR) was used. This method, recently developed by Adžić et al., consists of the use of a monolayer of a third metal, which can be deposited at an underpotential, as a template for the spontaneous deposition of a more noble metal. Herein, we choose zinc as template for the deposition of cobalt. Ag(111) crystals were covered by monolayer islands consisting of cobalt, with the surface atomic ratios ranging from 12 to 39% for cobalt. The catalytic activity of such samples towards ORR was evaluated and the best improvement in activity was found to be that of the sample with a cobalt percentage of approximately 30% with respect to the bare silver, which is in good agreement with theoretical hypotheses.

  16. Discovery of the Cobalt Isotopes

    OpenAIRE

    Szymanski, T.; Thoennessen, M.

    2009-01-01

    Twenty-six cobalt isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  17. 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.

  18. 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.

  19. Effective Pincer Cobalt Precatalysts for Lewis Acid Assisted CO2 Hydrogenation.

    Science.gov (United States)

    Spentzos, Ariana Z; Barnes, Charles L; Bernskoetter, Wesley H

    2016-08-15

    The pincer ligand MeN[CH2CH2(P(i)Pr2)]2 ((iPr)PNP) was employed to support a series of cobalt(I) complexes, which were crystallographically characterized. A cobalt monochloride species, ((iPr)PNP)CoCl, served as a precursor for the preparation of several cobalt precatalysts for CO2 hydrogenation, including a cationic dicarbonyl cobalt complex, [((iPr)PNP)Co(CO)2](+). When paired with the Lewis acid lithium triflate, [((iPr)PNP)Co(CO)2](+) affords turnover numbers near 30 000 (at 1000 psi, 45 °C) for CO2-to-formate hydrogenation, which is a notable increase in activity from previously reported homogeneous cobalt catalysts. Though mechanistic information regarding the function of the precatalysts remains limited, multiple experiments suggest the active species is a molecular, homogeneous [((iPr)PNP)Co] complex.

  20. 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.

  1. 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....

  2. COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

    OpenAIRE

    Liudmila V. Dyakova; Aleksander G. Kasikov; Elena S. Kshumaneva; Svetlana V. Drogobuzhskaya

    2010-01-01

    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 cob...

  3. Supplementation of cobalt to UASB reactors by pulse dosing: CoCl2 versus CoEDTA(2-) pulses

    NARCIS (Netherlands)

    Fermoso, F.G.; Bartacek, J.; Chung, L.C.; Lens, P.N.L.

    2008-01-01

    The effect of chelation on the dosing strategy of cobalt to restore the performance of a cobalt limited methanol-fed bioreactor was investigated. Three upflow anaerobic sludge bed (UASB) reactors (30 degrees C, pH 7.0) were operated with methanol as the substrate at an organic loading rate of 8.5 g

  4. 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.

  5. Cobalt and marine redox evolution

    Science.gov (United States)

    Swanner, Elizabeth D.; Planavsky, Noah J.; Lalonde, Stefan V.; Robbins, Leslie J.; Bekker, Andrey; Rouxel, Olivier J.; Saito, Mak A.; Kappler, Andreas; Mojzsis, Stephen J.; Konhauser, Kurt O.

    2014-03-01

    Cobalt (Co) is a bio-essential trace element and limiting nutrient in some regions of the modern oceans. It has been proposed that Co was more abundant in poorly ventilated Precambrian oceans based on the greater utilization of Co by anaerobic microbes relative to plants and animals. However, there are few empirical or theoretical constraints on the history of seawater Co concentrations. Herein, we present a survey of authigenic Co in marine sediments (iron formations, authigenic pyrite and bulk euxinic shales) with the goal of tracking changes in the marine Co reservoir throughout Earth's history. We further provide an overview of the modern marine Co cycle, which we use as a platform to evaluate how changes in the redox state of Earth's surface were likely to have affected marine Co concentrations. Based on sedimentary Co contents and our understanding of marine Co sources and sinks, we propose that from ca. 2.8 to 1.8 Ga the large volume of hydrothermal fluids circulating through abundant submarine ultramafic rocks along with a predominantly anoxic ocean with a low capacity for Co burial resulted in a large dissolved marine Co reservoir. We tentatively propose that there was a decrease in marine Co concentrations after ca. 1.8 Ga resulting from waning hydrothermal Co sources and the expansion of sulfide Co burial flux. Changes in the Co reservoir due to deep-water ventilation in the Neoproterozoic, if they occurred, are not resolvable with the current dataset. Rather, Co enrichments in Phanerozoic euxinic shales deposited during ocean anoxic events (OAE) indicate Co mobilization from expanded anoxic sediments and enhanced hydrothermal sources. A new record of marine Co concentrations provides a platform from which we can reevaluate the role that environmental Co concentrations played in shaping biological Co utilization throughout Earth's history.

  6. Controlling the misuse of cobalt in horses.

    Science.gov (United States)

    Ho, Emmie N M; Chan, George H M; Wan, Terence S M; Curl, Peter; Riggs, Christopher M; Hurley, Michael J; Sykes, David

    2015-01-01

    Cobalt is a well-established inducer of hypoxia-like responses, which can cause gene modulation at the hypoxia inducible factor pathway to induce erythropoietin transcription. Cobalt salts are orally active, inexpensive, and easily accessible. It is an attractive blood doping agent for enhancing aerobic performance. Indeed, recent intelligence and investigations have confirmed cobalt was being abused in equine sports. In this paper, population surveys of total cobalt in raceday samples were conducted using inductively coupled plasma mass spectrometry (ICP-MS). Urinary threshold of 75 ng/mL and plasma threshold of 2 ng/mL could be proposed for the control of cobalt misuse in raceday or in-competition samples. Results from administration trials with cobalt-containing supplements showed that common supplements could elevate urinary and plasma cobalt levels above the proposed thresholds within 24 h of administration. It would therefore be necessary to ban the use of cobalt-containing supplements on raceday as well as on the day before racing in order to implement and enforce the proposed thresholds. Since the abuse with huge quantities of cobalt salts can be done during training while the use of legitimate cobalt-containing supplements are also allowed, different urinary and plasma cobalt thresholds would be required to control cobalt abuse in non-raceday or out-of-competition samples. This could be achieved by setting the thresholds above the maximum urinary and plasma cobalt concentrations observed or anticipated from the normal use of legitimate cobalt-containing supplements. Urinary threshold of 2000 ng/mL and plasma threshold of 10 ng/mL were thus proposed for the control of cobalt abuse in non-raceday or out-of-competition samples. Copyright © 2014 John Wiley & Sons, Ltd.

  7. 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)

  8. Pharmacokinetics and dosimetry of cobalt-55 and cobalt-57

    NARCIS (Netherlands)

    Jansen, HML; Knollema, S; vanderDuin, LV; Willemsen, ATM; Wiersma, A; Franssen, EJF; Russel, FGM; Korf, J; Paans, AMJ

    1996-01-01

    The isotopes Co-55 and Co-57 have been evaluated for PET and SPECT imaging in several clinical brain studies. For clinical application of cobalt, it is important to know the delivered radiation dose. The biodistribution of Co-55 in both rat and humans after intravenous (bolus)-administration was

  9. 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.

  10. 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.

  11. 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.

  12. Determination of trace cobalt concentrations in human serum by adsorptive stripping voltammetry.

    Science.gov (United States)

    Kajic, Petra; Milosev, Ingrid; Pihlar, Boris; Pisot, Venceslav

    2003-01-01

    The goal of our study was to develop an accurate and reliable method for determining trace cobalt concentrations in human serum. The method was used to determine cobalt in the sera of healthy persons and patients with orthopaedic implants containing cobalt - a possible source of systemic release of cobalt into the human body. This goal is of vital interest since cobalt and its compounds are classified by IARC as potentially carcinogenic to humans. We used an electrochemical method, adsorptive stripping voltammetry (AdSV), which made possible the low detection limit and high sensitivity needed for measurements in human serum. The serum was acid digested by a combination of H2SO4, HNO3 and H2O2 in a 10 mL Kjeldhal flask. The digested sample was then dissolved in 0.1 mol/L ammonia buffer, pH 9.0 +/- 0.2. The determination is based on the adsorptive collection of the complex of cobalt (II) with dimethylglyoxime on a hanging mercury drop electrode (HMDE). The optimum values of adsorption potential and time were determined to be -0.8 V and 60 s. The optimisation of the sample digestion protocol and measurement procedures ensured the reliable assessment of low cobalt concentrations, down to 0.03 microg/L. The mean concentration of serum cobalt in four healthy persons was 0.11 +/- 0.06 microg/L, and in four patients with total hip replacements 0.34 +/- 0.07 microg/L. This method will be used routinely for measuring serum cobalt levels in patients with total hip replacements.

  13. 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.

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

    Science.gov (United States)

    Zhuang, Quan-Quan; Lin, Zhi-Hang; Jiang, Yan-Cheng; Deng, Hao-Hua; He, Shao-Bin; Su, Li-Ting; Shi, Xiao-Qiong; Chen, Wei

    2017-01-01

    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.

  15. 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 ethylenedi

  16. 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

  17. 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 ethylenedi

  18. 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.

  19. 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...

  20. Hot Corrosion of Cobalt-Base Alloys

    Science.gov (United States)

    1975-06-01

    scale is similar to that which has already been proposed for cobalt . The oxide ions would react with the Al203 to form aluminate ions in the Na2S04...resistance of cobalt -base and nickel-base alloys. The contract was accomplished under the technical direction of Dr. H. C. Graham of the Aerospace Research...Oxidized Specimens RESULTS AND DISCUSSION 1. INTRODUCfiON 2. SODIUM SULFATE INDUCED HOT CORROSION OF COBALT a. Introduction b. Experimental c

  1. Cobalt-Base Alloy Gun Barrel Study

    Science.gov (United States)

    2014-07-01

    are presented in Section 5. 2. Materials and methods The composition of the cobalt -base alloy (CBA) is presented in Table 1. The production of this... Cobalt -Base Alloy Gun Barrel Study by William S. de Rosset and Jonathan S. Montgomery ARL-RP-0491 July 2014 A reprint...21005-5069 ARL-RP-0491 July 2014 Cobalt -Base Alloy Gun Barrel Study William S. de Rosset and Jonathan S. Montgomery Weapons and Materials

  2. 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.

  3. Effect of vitamin B12 pulse addition on the performance of cobalt deprived anaerobic granular sludge bioreactors

    KAUST Repository

    Fermoso, Fernando G.

    2010-07-01

    The effect of a pulse addition of vitamin B12 as cobalt source to restore the performance of cobalt depleted methanol-fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was supplied with a pulse of vitamin B12, and its operation was compared to that of another cobalt depleted UASB reactor to which a pulse of CoCl2 was given. The addition of cobalt in the form of CoCl2 supplies enough cobalt to restore methanogenesis and maintain full methanol degradation coupled to methane production during more than 35 days after the CoCl2 pulse. Similar to CoCl2, pulse addition of vitamin B12 supplies enough cobalt to maintain full methanol degradation during more than 35 days after the pulse. However, the specific methanogenic activities (SMAs) of the sludge in the vitamin B12 supplied reactor were around 3 times higher than the SMA of the sludge from the CoCl2 supplied reactor at the same sampling times. An appropriate dosing strategy (repeated pulse dosing) combined with the choice of vitamin B12 as the cobalt species is suggested as a promising dosing strategy for methanol-fed anaerobic bioreactors limited by the micronutrient cobalt. © 2010 Elsevier Ltd. All rights reserved.

  4. Biological synthesis of cobalt ferrite nanoparticles

    Directory of Open Access Journals (Sweden)

    Anal K. Jha

    2012-01-01

    Full Text Available A low-cost green and reproducible yeast (Saccharomyces cerevisiae mediated biosynthesis of cobalt ferrite nanoparticles is reported. The synthesis is performed at close to room temperature in the laboratory. X-ray, Fourier transform infrared spectroscopy and high resolution transmission electron microscopy analyses are performed to ascertain the formation of cobalt ferrite nanoparticles. Individual nanoparticles, as well as a very few aggregate having the size of 3-15 nm, were found. The vibrating sample magnetometer measurement showed superparamagnetic behavior in cobalt ferrite nanoparticles. The mechanism involved in the biosynthesis of cobalt ferrite nanoparticles has also been discussed.

  5. Oxidation of low cobalt alloys

    Science.gov (United States)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  6. Simultaneous determination of seven impurities in high-purity cobalt oxide by ICP-AES after matrix separation using 1-nitroso-2-naphthol as a precipitant

    Institute of Scientific and Technical Information of China (English)

    王艳; 周春山; 段青兵; 陈萍

    2002-01-01

    A method was developed for the simultaneous determination of seven trace impurities (Cd, Mn, Pb, Zn, Cu, Fe and Ni) in high-purity cobalt oxide by ICP-AES. The matrix effect was eliminated by preci- pitation with 1-nitroso-2-naphthol. The matrix effect of cobalt on the absorptions of trace impurities, the effects of reaction time, pH value, dosage of precipitant on the formation of cobalt-1-nitroso-2-naphthol complex, the effects of hydrochloric acid on the stability of this complex and masking of elements were studied. Recoveries of the impurities in spiked sample are from 90% to 110% with a precision of 1.1%-5.0% RSD. The detection limits of the seven elements are in the range of 0.01-0.24μg/g. The method can be applied to the analysis of high-purity cobalt metal, cobalt oxide and other cobalt compounds.

  7. 40 CFR 421.232 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Science.gov (United States)

    2010-07-01

    ..., nickel, and cobalt in the crushed raw material Copper 0.146 0.077 Nickel 0.148 0.098 Ammonia (as N) 10.../kg (pounds per million pounds) of cobalt produced Copper 40.660 21.400 Nickel 41.080 27.180 Ammonia... CATEGORY Primary Nickel and Cobalt Subcategory § 421.232 Effluent limitations guidelines representing...

  8. Determination of trace amounts of cobalt in blood

    Energy Technology Data Exchange (ETDEWEB)

    Godlewska, B.; Hulanicki, A. [Univ. of Warsaw (Poland); Abou-Shakra, F.R. [Univ. of Surrey, Guildford (United Kingdom)] [and others

    1994-11-01

    The analysis of cobalt in whole blood and blood fractions has been carried out using three different analytical techniques namely, electrothermal atomic absorption spectrometry, inductively coupled plasma mass spectrometry and cathodic stripping voltammetry. This study showed that inductively coupled plasma mass spectrometry was the better equipped technique for conducting such analyses due to its low detection limits and wide linear dynamic range. The results ranged between 0.7 - 2.62 {mu}g/l for plasma, 1.02 - 2.31 {mu}g/l for serum, and 0.66 - 1.28 {mu}g/l for whole blood. The introduction of different forms of cobalt to Wistar rats resulted in a differing distribution of the element between serum and whole blood. This observation suggests that there are at least two modes of Co uptake and transport depending on the administered or taken chemical form.

  9. Inhalation cancer risk assessment of cobalt metal.

    Science.gov (United States)

    Suh, Mina; Thompson, Chad M; Brorby, Gregory P; Mittal, Liz; Proctor, Deborah M

    2016-08-01

    Cobalt compounds (metal, salts, hard metals, oxides, and alloys) are used widely in various industrial, medical and military applications. Chronic inhalation exposure to cobalt metal and cobalt sulfate has caused lung cancer in rats and mice, as well as systemic tumors in rats. Cobalt compounds are listed as probable or possible human carcinogens by some agencies, and there is a need for quantitative cancer toxicity criteria. The U.S. Environmental Protection Agency has derived a provisional inhalation unit risk (IUR) of 0.009 per μg/m(3) based on a chronic inhalation study of soluble cobalt sulfate heptahydrate; however, a recent 2-year cancer bioassay affords the opportunity to derive IURs specifically for cobalt metal. The mechanistic data support that the carcinogenic mode of action (MOA) is likely to involve oxidative stress, and thus, non-linear/threshold mechanisms. However, the lack of a detailed MOA and use of high, toxic exposure concentrations in the bioassay (≥1.25 mg/m(3)) preclude derivation of a reference concentration (RfC) protective of cancer. Several analyses resulted in an IUR of 0.003 per μg/m(3) for cobalt metal, which is ∼3-fold less potent than the provisional IUR. Future research should focus on establishing the exposure-response for key precursor events to improve cobalt metal risk assessment.

  10. Cobalt particle size effects in catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.

    2010-01-01

    Aim of the work described in this thesis was first to investigate cobalt particle size effects in heterogeneous catalysis. The main focus was to provide a deeper understanding of the origin of the cobalt particle size effects in Fischer-Tropsch (FT) catalysis in which synthesis gas (H2/CO) is conver

  11. 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.

  12. Cobalt Complexes as Antiviral and Antibacterial Agents

    OpenAIRE

    Eddie L. Chang; Christa Simmers; D. Andrew Knight

    2010-01-01

    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(NH3)6]3+ ion.

  13. Cobalt particle size effects in catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.

    2010-01-01

    Aim of the work described in this thesis was first to investigate cobalt particle size effects in heterogeneous catalysis. The main focus was to provide a deeper understanding of the origin of the cobalt particle size effects in Fischer-Tropsch (FT) catalysis in which synthesis gas (H2/CO) is

  14. 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

  15. Study of Cobalt(III) Corrole as the Neutral Ionophore for Nitrite and Nitrate Detection via Polymeric Membrane Electrodes.

    Science.gov (United States)

    Yang, Si; Meyerhoff, Mark E

    2013-12-01

    Cobalt(III) 5, 10, 15-tris(4-tert-butylphenyl) corrole was synthesized and incorporated into plasticized poly(vinyl chloride) membranes and studied as a neutral carrier ionophore via potentiometry. This cobalt(III) complex has binding affinity to nitrite, and the resulting membrane electrode yields reversible and Nernstian response toward nitrite. Enhanced nitrite selectivity is observed over other anions, including lipophilic anions such as thiocyanate and perchlorate when an appropriate amount of lipophilic cationic sites are added to the membrane phase. Detection limit to nitrite is ca. 5 µM. Using tributylphosphate as the plasticizer with the cobalt(III) corrole species yields electrodes with enhanced nitrate selectivity.

  16. 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...

  17. Enhanced electrochemical properties of cobalt doped manganese dioxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byung Chul; Justin Raj, C.; Cho, Won-Je; Lee, Won-Gil [Department of Chemistry, Dongguk University-Seoul, Seoul 100-715 (Korea, Republic of); Jeong, Hyeon Taek [ARC Centre of Excellence for Electromaterials Science, IPRI, AIIM Facility, Innovation Campus, University of Wollongong, NSW 2522 (Australia); Yu, Kook Hyun, E-mail: yukook@dongguk.edu [Department of Chemistry, Dongguk University-Seoul, Seoul 100-715 (Korea, Republic of)

    2014-12-25

    Highlights: • Cobalt doped MnO{sub 2} nanowires were synthesized by the hydrothermal method. • Supercapacitor properties of Co–MnO{sub 2} electrodes were studied. • Cobalt content enhanced the conductivity and specific capacitance of MnO{sub 2}. • 5% Co doped MnO{sub 2} electrode shows 415 F g{sup −1} with excellent cyclic stability. - Abstract: The various molar concentrations of cobalt doped manganese dioxide (Co–MnO{sub 2}) nanostructures were synthesized by an hydrothermal technique for electrochemical supercapacitor application. The X-ray diffraction analysis showed that the samples were composed of multiphase of MnO{sub 2} with dominant reflections of γ-MnO{sub 2} structure of crystallization. The morphological studies displayed the existence of MnO{sub 2} nanowires with the width of 10–20 nm and showing a good degree of crystallization. The electrochemical characterization was performed using cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 1 M Na{sub 2}SO{sub 4} aqueous electrolyte. All the samples exhibit a typical ideal capacitive behavior with an increasing order of specific capacitance values with respect to the increase in the concentration of cobalt ions up to a certain limit. The specific capacitance of 415 F g{sup −1} was delivered by 5% Co–MnO{sub 2} sample at 0.2 A g{sup −1} which was nearly double that of bare MnO{sub 2} electrode of 231 F g{sup −1}. Moreover, the Co–MnO{sub 2} electrode shows an excellent capacitance retention (97.3%) after 5000 charge and discharge cycles.

  18. Advances in cobalt complexes as anticancer agents.

    Science.gov (United States)

    Munteanu, Catherine R; Suntharalingam, Kogularamanan

    2015-08-21

    The evolution of resistance to traditional platinum-based anticancer drugs has compelled researchers to investigate the cytostatic properties of alternative transition metal-based compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. This perspective catalogues the development of antiproliferative cobalt complexes, and provides an in depth analysis of their mode of action. Early studies on simple cobalt coordination complexes, Schiff base complexes, and cobalt-carbonyl clusters will be documented. The physiologically relevant redox properties of cobalt will be highlighted and the role this plays in the preparation of hypoxia selective prodrugs and imaging agents will be discussed. The use of cobalt-containing cobalamin as a cancer specific delivery agent for cytotoxins will also be described. The work summarised in this perspective shows that the biochemical and biophysical properties of cobalt-containing compounds can be fine-tuned to produce new generations of anticancer agents with clinically relevant efficacies.

  19. Cobalt-mediated radical polymerization of vinyl monomers: investigation of cobalt-coordination

    OpenAIRE

    2009-01-01

    Controlled Radical Polymerization techniques have been developed to obtain well-defined architectures and to control polymer parameters. Among these systems is Cobalt-Mediated Radical Polymerization (CMRP), which is based on the reversible deactivation of the growing radical chains with a cobalt complex, the cobalt (II) bis(acetylacetonate). The interest of this system is not only due to its ability to control the polymerization of very reactive monomers such as vinyl acetate (VAc) and N-viny...

  20. Flotation of cobalt bearing minerals from a mixed copper-cobalt oxidized ore

    OpenAIRE

    2012-01-01

    M.Tech. (Extraction Metallurgy) The techniques for the flotation of mixed copper and cobalt bearing oxide ores using the sulphidization method in order to recover the oxidized copper and cobalt bearing minerals have been well documented by previous researchers. These processes have been successfully implemented in many of the metallurgical plant operations in the Democratic Republic of Congo (DRC). The mixed copper and cobalt oxidised ores from this region present significant chal-lenges t...

  1. Galvanic cells including cobalt-chromium alloys.

    Science.gov (United States)

    Gjerdet, N R

    1980-01-01

    Galvanic cells may be created when dentures made of cobalt-chromium alloys are placed on teeth with metallic restorations. The power of such cells was evaluated in an in vitro galvanic using amalgams, gold alloy, and nickel-chromium alloys. The amalgams and one of the nickel-chromium alloys revealed high corrosion currents when placed in contact with cobalt-chromium alloy, the conventional amalgam showing the highest values. The gold alloy and another nickel-chromium alloy exhibited low corrosion currents and they were noble with respect to cobalt-chromium.

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

    OpenAIRE

    2015-01-01

    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)(N3)2], [Co(N2H4)2(N3)2], and [Co(N2H4)(N3)Cl]·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 oxidiz...

  3. 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. ...

  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...... is to act both as a diffusion barrier for chromium and provide better protection against high temperature oxidation than a pure cobalt coating. This work presents a characterization of a cobalt-tungsten alloy coating electrodeposited on the ferritic steel Crofer 22 H which subsequently was oxidized in air...... of oxidation time. The coating had completely oxidized during the 300 h oxidation time. GDOES measurements showed that the tungsten was located in an inner zone in the coating/substrate interface. The outer layer of the coating did not contain any tungsten after oxidation but consisted mainly of cobalt...

  5. Cobalt-related defects in silicon

    Science.gov (United States)

    Gibbons, T. M.; Backlund, D. J.; Estreicher, S. K.

    2017-01-01

    Transition metals from the 3d series are unavoidable and unwanted contaminants in Si-based devices. Cobalt is one of the most poorly understood impurities with incomplete experimental information and few theoretical studies. In this contribution, the properties of interstitial cobalt (Coi) in Si and its interactions with the vacancy, self-interstitial, hydrogen, and substitutional boron are calculated using the first-principles tools. The stable configurations, gap levels, and binding energies are predicted. The activation energy for diffusing Coi is calculated with the nudged-elastic-band method and found to be slightly lower than that of interstitial copper and nickel. The binding energies and gap levels of the substitutional cobalt (Cos) and of the {Cos,H} and {Cos,H,H} complexes are close to the experimental data. The properties of the cobalt-boron pair are calculated.

  6. 40 CFR 437.23 - Effluent limitations attainable by the application of the best available technology economically...

    Science.gov (United States)

    2010-07-01

    ... CENTRALIZED WASTE TREATMENT POINT SOURCE CATEGORY Oils Treatment and Recovery § 437.23 Effluent limitations..., cadmium, chromium, cobalt, copper, lead, mercury, tin, zinc, butylbenzyl phthalate, carbazole,...

  7. 40 CFR 437.13 - Effluent limitations attainable by the application of the best available technology economically...

    Science.gov (United States)

    2010-07-01

    ... CENTRALIZED WASTE TREATMENT POINT SOURCE CATEGORY Metals Treatment and Recovery § 437.13 Effluent limitations... antimony, arsenic, cadmium, chromium, cobalt, copper, lead, mercury, nickel, silver, tin,...

  8. 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....

  9. Trace determination of cobalt ion by using malic acid-malonic acid double substrate oscillating chemical system

    Institute of Scientific and Technical Information of China (English)

    Jie Wang; Wu Yang; Jie Ren; Miao Guo; Xiao Dong Chen; Wen Bin Wang; Jin Zhang Gao

    2008-01-01

    A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii (B-Z) oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10-8 to 5.37×10-12mol L-1 the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 x 10-13 mol L-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.

  10. 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.

  11. 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.

  12. Intolerability of cobalt salt as erythropoietic agent.

    Science.gov (United States)

    Ebert, Bastian; Jelkmann, Wolfgang

    2014-03-01

    Unfair athletes seek ways to stimulate erythropoiesis, because the mass of haemoglobin is a critical factor in aerobic sports. Here, the potential misuse of cobalt deserves special attention. Cobalt ions (Co(2+) ) stabilize the hypoxia-inducible transcription factors (HIFs) that increase the expression of the erythropoietin (Epo) gene. Co(2+) is orally active, easy to obtain, and inexpensive. However, its intake can bear risks to health. To elaborate this issue, a review of the pertinent literature was retrieved by a search with the keywords 'anaemia', 'cobalt', 'cobalt chloride', 'erythropoiesis', 'erythropoietin', 'Epo', 'side-effects' and 'treatment', amongst others. In earlier years, cobalt chloride was administered at daily doses of 25 to 300 mg for use as an anti-anaemic agent. Co(2+) therapy proved effective in stimulating erythropoiesis in both non-renal and renal anaemia, yet there were also serious medical adverse effects. The intake of inorganic cobalt can cause severe organ damage, concerning primarily the gastrointestinal tract, the thyroid, the heart and the sensory systems. These insights should keep athletes off taking Co(2+) to stimulate erythropoiesis.

  13. [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.

  14. Development of a Cloud-Point Extraction Method for Cobalt Determination in Natural Water Samples

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Jamali

    2013-01-01

    Full Text Available A new, simple, and versatile cloud-point extraction (CPE methodology has been developed for the separation and preconcentration of cobalt. The cobalt ions in the initial aqueous solution were complexed with 4-Benzylpiperidinedithiocarbamate, and Triton X-114 was added as surfactant. Dilution of the surfactant-rich phase with acidified ethanol was performed after phase separation, and the cobalt content was measured by flame atomic absorption spectrometry. The main factors affecting CPE procedure, such as pH, concentration of ligand, amount of Triton X-114, equilibrium temperature, and incubation time were investigated and optimized. Under the optimal conditions, the limit of detection (LOD for cobalt was 0.5 μg L-1, with sensitivity enhancement factor (EF of 67. Calibration curve was linear in the range of 2–150 μg L-1, and relative standard deviation was 3.2% (c=100 μg L-1; n=10. The proposed method was applied to the determination of trace cobalt in real water samples with satisfactory analytical results.

  15. Suppression of superconductivity and resistivity anomaly in Rh17S15 by cobalt substitution

    Science.gov (United States)

    Daou, Ramzy; Berthebaud, David; Maignan, Antoine

    2017-02-01

    The chalcogenide superconductor Rh17S15 is known for having an upper critical field of nearly twice the Pauli limit and an unusual temperature dependence of the resistivity. When doped with small amounts of cobalt, superconductivity in Rh17-x Co x S15 (0  superconductivity.

  16. Trace and selective determination of cobalt(II in water and salt samples using cathodic adsorptive stripping voltammetry in the presence of pyrogallol red

    Directory of Open Access Journals (Sweden)

    Hasanpour Foroozan

    2013-01-01

    Full Text Available A sensitive and selective procedure is presented for voltammetric determination of cobalt. The procedure involves an adsorptive accumulation of cobalt pyrogallol red (PGR complex on stationary mercury drop electrode, followed by cathodic stripping voltammetry measurement of reduction current of adsorbed complex at -1.17 V (vs. Ag/AgCl. The optimum conditions for determination of cobalt include pH 11.0, 35 μM pyrogallol red, an accumulation potential of -0.9 V (vs. Ag/AgCl and scan rate 80 mVs-1. The peak current is proportional to the concentration of cobalt over the concentration range of 5.0 to 280 ng mL-1 with a detection limit of 1 ng mL-1 with an accumulation time of 140 s. The method was applied for the determination of cobalt in analytical grade NaCl and water samples.

  17. INFLUENCE OF COBALT IONS ON ENZYME ACTIVTY OF ISOCITRIATE LYASE AND ITS REGULATION IN CONDITION OF SEED GERMINATION OF GLYCINE MAX L

    National Research Council Canada - National Science Library

    Chechui O. F

    2012-01-01

    We investigated the activity of isocitrate lyase in seeds of Glycine max L. after 24, 72, and 120 hours of germination and effect of cobalt ions on the activity of the enzyme in time limit of the experiment...

  18. Cyclam Modified Carbon Paste Electrode as a Potentiometric Sensor For Determination of Cobalt(Ⅱ) Ions

    Institute of Scientific and Technical Information of China (English)

    Hamid Reza POURETEDAL; Mohammad Hossein KESHAVARZ

    2005-01-01

    A new modified carbon paste electrode based on cyclam as a modifier was prepared for the determination of Co(Ⅱ) ions. The proposed electrode shows a Nernstian slope 28.4 mV per decade over a wide concentration range 5.0×10-6_1.0×10-1 mol/L of Co2+ ions with detection limit 2.5×10-6 mol/L. The sensor exhibits good selectivities for Co2+ over a wide variety of other cations. It can be used as an indicator electrode in potentiometric titration of cobalt(Ⅱ) ions as well as in direct determination of cobalt(Ⅱ) ions in wastewater of acidic cobalt electroplating bath. The electrode shows Nernestian behavior in a solution of 25% ethanol.

  19. β-cyclodextrin-cobalt ferrite nanocomposite as enhanced sensing platform for catechol determination.

    Science.gov (United States)

    Han, Jin-Tu; Huang, Ke-Jing; Li, Jing; Liu, Yan-Ming; Yu, Meng

    2012-10-01

    An electrochemical sensor based on β-cyclodextrin-cobalt ferrite nanocomposite was developed for the sensitive detection of catechol (CT). To construct the base of the sensor, a novel composite was initially fabricated and used as the substrate material by combining cobalt ferrite nanocomposite and β-cyclodextrin via a simple sonication-induced assembly. Due to the high catechol-loading capacity on the electrode surface and the upstanding electric conductivity of cobalt ferrite nanocomposite, the electrochemical response of the fabricated sensor was greatly enhanced and displayed excellent analytical performance for catechol detection from 1 to 200 μM with a low detection limit of 0.12 μM (S/N=3). Moreover, the developed electrochemical sensor exhibited good selectivity and acceptable reproducibility and could be used for the detection of catechol in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Electrocatalytic miRNA Detection Using Cobalt Porphyrin-Modified Reduced Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Camille De Souza

    2014-06-01

    Full Text Available Metalated porphyrins have been described to bind nucleic acids. Additionally, cobalt porphyrins present catalytic properties towards oxygen reduction. In this work, a carboxylic acid-functionalized cobalt porphyrin was physisorbed on reduced graphene oxide, then immobilized on glassy carbon electrodes. The carboxylic groups were used to covalently graft amino-terminated oligonucleotide probes which are complementary to a short microRNA target. It was shown that the catalytic oxygen electroreduction on cobalt porphyrin increases upon hybridization of miRNA strand (“signal-on” response. Current changes are amplified compared to non-catalytic amperometric system. Apart from oxygen, no added reagent is necessary. A limit of detection in the sub-nanomolar range was reached. This approach has never been described in the literature.

  1. 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...

  2. 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....

  3. Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

    Science.gov (United States)

    Qi, B.; Andrew, J. S.; Arnold, D. P.

    2017-03-01

    This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain ( 100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

  4. Diagnostic Value of the Cobalt ({sup 58}Co) Excretion Test in Iron Deficiency Anemia

    Energy Technology Data Exchange (ETDEWEB)

    Sihn, Hyun Chung; Hong, Kee Suck; Cho, Kyung Sam; Song, In Kyung; Koh, Chang Soon; Lee, Mun Ho [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1976-03-15

    The diagnosis of iron deficiency rests upon the correct evaluation of body iron stores. Morphological interpretation of blood film and the red cell indices are not reliable and often absent in mild iron deficiency. Serum iron levels and iron-binding capacity are more sensitive indices of iron deficiency, but they are often normal in iron depletion and mild iron deficiency anemia. They are also subject ro many variables which may introduce substantial errors and influenced by many pathologic and physiologic states. Examination of the bone marrow aspirate for stainable iron has been regarded as one of the most sensitive and reliable diagnostic method for detecting iron deficiency, but this also has limitations. Thus, there is still need for a more practical, but sensitive and reliable substitute as a screening test of iron deficiency. Pollack et al. (1965) observed that the intestinal absorption of cobalt was raised in iron, deficient rats and Valberg et al. (1969) found that cobalt absorption was elevated in patients with iron deficiency. A direct correlation was demonstrated between the amounts of radioiron and radiocobalt absorbed. Unlike iron, excess cobalt was excreted by the kidney, the percentage of radioactivity in the urine being directly related to the percentage absorbed from the gastro-intestinal tract. Recently a test based on the urinary excretion of an oral dose of {sup 57}Co has been proposed as a method for detecting iron deficiency. To assess the diagnostic value of urinary cobalt excretion test cobaltous chloride labelled with 1 muCi of {sup 58}Co was given by mouth and the percentage of the test dose excreted in the urine was measured by a gamma counter. The mean 24 hour urinary cobalt excretion in control subjects with normal iron stores was 6.1%(1.9-15.2%). Cobalt excretion was markedly increased in patients with iron deficiency and excreted more than 29% of the dose. In contrast, patients with anemia due to causes other than iron deficiency

  5. 40 CFR 415.652 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Science.gov (United States)

    2010-07-01

    ... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.652 Effluent limitations guidelines... available (BPT): Subpart BM—Cobalt Salts Pollutant or pollutant property BPT effluent limitations Maximum... product TSS 0.0023 0.0014 Cobalt (T) 0.0003 0.00012 Copper (T) 2.7×10−4 8.3×10−5 Nickel (T) 2.7×10−4...

  6. 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.

  7. 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

  8. 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.

  9. Supported cobalt catalysts - preparation, characterization and reaction studies

    OpenAIRE

    Backman, Leif

    2009-01-01

    The aim of this work was to understand on the effect of thermal treatments, precursor and support on the interaction between the support and cobalt species, and further how the interaction affects the reducibility and dispersion of the catalyst. Silica and alumina supported cobalt catalysts were prepared, characterised and tested for catalytic activity. The catalysts were prepared by gas phase deposition techniques from cobalt acetylacetonate and cobalt carbonyl and by incipient wetness impre...

  10. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation

    OpenAIRE

    Majtan, Tomas; Frerman, Frank E.; Kraus, Jan P.

    2010-01-01

    Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound c...

  11. 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.

  12. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    Science.gov (United States)

    Adzic, Radoslav; Huang, Tao

    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.

  13. 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...

  14. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung epithelial cells.

    Science.gov (United States)

    Xie, Hong; Smith, Leah J; Holmes, Amie L; Zheng, Tongzhang; Pierce Wise, John

    2016-05-01

    Cobalt is a toxic metal used in various industrial applications leading to adverse lung effects by inhalation. 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, especially normal lung epithelial cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in normal primary human lung epithelial 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 and particulate cobalt induced similar cytotoxicity while soluble cobalt was more genotoxic than particulate cobalt. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung epithelial cells.

  15. A Rapid In Situ Colorimetric Assay for Cobalt Detection by the Naked Eye

    Directory of Open Access Journals (Sweden)

    Sung-Min Kang

    2016-05-01

    Full Text Available A simple, rapid, and convenient colorimetric chemosensor of a specific target toward the end user is still required for on-site detection and real-time monitoring applications. In this study, we developed a rapid in situ colorimetric assay for cobalt detection using the naked eye. Interestingly, a yellow to light orange visual color transition was observed within 3 s when a Chrysoidine G (CG chemosensor was exposed to cobalt. Surprisingly, the CG chemosensor had great selectivity toward cobalt without any interference of other metal ions. Under optimized conditions, a lower detection limit of 0.1 ppm via a spectrophotometer and a visual detection limit of 2 ppm with a linear range from 0.4 to 1 ppm (R2 = 0.97 were determined. Moreover, the CG chemosensor is reversible and maintains its functionality after treatment with chelating agents. In conclusion, we show the superior capabilities of the CG chemosensor, which has the potential to provide extremely facile handling, high sensitivity, and a fast response time for applications of on-site detection to real-time cobalt monitoring for the general public.

  16. Fast Low-Spin Cobalt Complex Redox Shuttles for Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Xie, Yuling; Hamann, Thomas W

    2013-01-17

    A low-spin cobalt(II) complex, cobalt bis(trithiacyclononane), [Co(ttcn)2](3+/2+), was investigated for use as a redox shuttle in dye-sensitized solar cells, DSSCs. This unique cobalt complex redox shuttle is stable, transparent, and easy to synthesize from commercial ligands and has attractive energetic and kinetic features for use in DSSCs. Initial results indicate that the overall performance is limited by recombination. Variation of the sensitizer and deposition of an ultrathin coating of alumina on nanoparticle-based TiO2 DSSC photoanodes reduced recombination, which resulted in significantly improved quantum yields. The photovoltaic behavior was compared to the current record efficiency cobalt tris-bipyridine, [Co(bpy)3](3+/2+), redox shuttle and produced similar results. Further use of high extinction organic sensitizers with only ∼200 mV of driving force for regeneration was examined, which produced efficiencies of over 2%; importantly, regeneration is not rate-limiting in this system, thus demonstrating the promise of using such fast redox shuttles.

  17. Electrochemical formation of holmium-cobalt alloys

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The electrochemical formation processes of holmium-cobalt alloys on cobalt cathode in molten HoC13-KC1 wereinvestigated by cyclic voltammetry and open current potential-time curve after potentiostatic electrolysis. The structure ofHo-Co alloys' films deposited on cobalt electrode by potentiostatic electrolysis was characterized by X-ray diffraction. Thestandard Gibbs free energies of formation for the intermetallic compounds of Ho and Co were determined. The diffusioncoefficient and diffusion activation energy of Ho atom in the alloy phase were calculated to be 10-10-10-11 cm2/s and 96.0kJ/mol, respectively, from the current-time curve at potential step.

  18. Total quality management of cobalt-60 sources

    Science.gov (United States)

    Malkoske, G. R.

    1999-06-01

    Total Quality Management of Cobalt-60 sources by a supplier requires a life cycle approach to source management. This covers various aspects, including design, manufacturing, installation, field inspection, source surveillance and return of cobalt-60 sources at the end of their useful life. The Total Quality Management approach demonstrates a strong industry commitment to the beneficial use of gamma technology for industrial irradiation applications in both developed nations and in those nations who are developing their infrastructure and techniques for the beneficial use of this technology. MDS Nordion continues to demonstrate its support and commitment to the industry by developing and implementing state-of-the-art standards for the safe use of cobalt-60 sources.

  19. 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

  20. 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.

  1. 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.

  2. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  3. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  4. A new cobalt oxide electrodeposit bath for solar absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Enrique [Departmento de IPH, Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana - Iztapalapa, Mexico D.F. (Mexico); Gonzalez, Ignacio [Departmento de Quimica, Area de Electroquimica, Universidad Autonoma Metropolitana - Iztapalapa, Mexico D.F. (Mexico); Viveros, Tomas [Departmento de IPH, Area de Ingenieria Quimica, Universidad Autonoma Metropolitana - Iztapalapa, Mexico D.F. (Mexico)

    1997-12-19

    A study was carried out in a Hull cell in order to optimize the deposition conditions of cobalt oxide (black cobalt) in an electrolytic bath, which uses cobalt nitrate for direct obtention of black cobalt. Thermal stability of the material was surveyed on several samples of black cobalt prepared on stainless-steel with a thickness of approximately of 2.5 {mu}m. It was found that the optical properties change, in respect to the initial values, with time of treatment until an equilibrium is reached. This equilibrium depends on the substrate and the temperature of the treatment used

  5. 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.

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

    Science.gov (United States)

    Smith, Leah J; Holmes, Amie L; Kandpal, Sanjeev Kumar; Mason, Michael D; Zheng, Tongzhang; Wise, John Pierce

    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.

  7. 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.

  8. Cobalt reduction of NSSS valve hardfacings for ALARA

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joo Hak; Lee, Sang Sub [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    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).

  9. 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.......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...... 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

  10. 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.

  11. 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...... that they are exposed to cobalt from handling work items, causing hand dermatitis. Objectives: To present early findings with a newly developed cobalt spot test. Methods and Results: A cobalt spot test based on disodium-1-nitroso-2-naphthol-3,6-disulfonate was able to identify cobalt release at 8.3 ppm. The test may...... 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...

  12. Surface magnetism in iron, cobalt, and nickel

    DEFF Research Database (Denmark)

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

    1992-01-01

    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...

  13. 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

  14. Evidence of Formation of Superdense Nonmagnetic Cobalt

    Science.gov (United States)

    Banu, Nasrin; Singh, Surendra; Satpati, B.; Roy, A.; Basu, S.; Chakraborty, P.; Movva, Hema C. P.; Lauter, V.; Dev, B. N.

    2017-02-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure.

  15. 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.

  16. Cobalt Biogeochemistry in the South Atlantic: A Full-Depth Zonal Ocean Section of Total Dissolved Cobalt, and Development of a High Throughput Cobalt ICP-MS Method

    Science.gov (United States)

    Noble, A. E.; Saito, M. A.; Goepfert, T. J.

    2008-12-01

    This study presents the first high-resolution full-depth zonal section of total dissolved cobalt from a recent cruise transecting the South Atlantic Ocean along approximately 11S. This section demonstrates that current electrochemical analytical techniques are capable of producing the high precision and high resolution datasets for total dissolved cobalt expected to be generated as a part of the international GEOTRACES Program. The micronutritive role of cobalt may affect community structure in different regions of the oceans, a compelling reason to include cobalt in the trace element analyses planned for the GEOTRACES Program. This cobalt section reveals an advective source of cobalt from the African coast near Namibia, which we propose to be due to the Benguela Current interacting with reducing shelf sediments. These high concentrations of cobalt were also observed within the oxygen minimum zone that extends across much of the South Atlantic basin in this section, and are likely indicative of redox cycling of cobalt in the water column. Nutrient-like vertical structure of cobalt was observed in the surface waters across the majority of the basin due to biological utilization, and the expected hybrid-type trend is observed at depth, with scavenging of cobalt below the nutricline. Deepwater concentrations of cobalt were around 50pM across the basin below 3000m. Analysis of the shelf-life of refrigerated filtered samples stored without acidification for electrochemical cobalt analysis demonstrated that those samples which were collected specifically within oxygen minimum zones may underestimate cobalt if not analyzed within a few weeks of collection. These results motivate our on-going development of a method to measure cobalt in acidified samples via inductively coupled plasma mass spectrometry (ICP-MS). The benefit of this technique would be twofold: acidification would extend the shelf-life of the samples significantly, and samples would be preserved identically

  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

    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...... to cobalt from handling work items, causing hand dermatitis....

  18. Effect of sodium citrate on preparation of nano-sized cobalt particles by organic colloidal process

    Institute of Scientific and Technical Information of China (English)

    Huaping ZHU; Hao LI; Huiyu SONG; Shijun LIAO

    2009-01-01

    Nano-sized cobalt particles with the diameter of 2 nm were prepared via an organic colloidal process with sodium formate, ethylene glycol and sodium citrate as the reducing agent, the solvent and the complexing agent, respectively. The effects of sodium citrate on the yield, crystal structure, particle size and size distribution of the prepared nano-sized cobalt particles were then investigated. The results show that the average particle diameter decreases from 200 nm to 2 nm when the molar ratio of sodium citrate to cobalt chloride changes from 0 to 6. Furthermore, sodium citrate plays a crucial role in the controlling of size distribution of the nano-sized particles. The size distribution of the particle without sodium citrate addition is in range from tens of nanometers to 300 or 400 nm, while that with sodium citrate addition is limited in the range of (2±0.25) nm. Moreover, it is found that the addition of sodium citrate as a complex agent could decrease the yield of the nano-sized cobalt particle.

  19. 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.

  20. 40 CFR 461.12 - Effluent limitations representing the degree of effluent reduction attainable by the application...

    Science.gov (United States)

    2010-07-01

    ... 2.96 Zinc 3.40 1.42 Cobalt 0.49 0.21 (6) Subpart A—Cadmium Powder Production. BAT Effluent... Cadmium 2.23 0.99 Nickel 12.61 8.34 Zinc 9.59 4.01 Cobalt 1.38 0.59 (7) Subpart A—Silver Powder Production....44 Cobalt 7.38 3.16 (2) Subpart A—Impregnated Anodes. BAT Effluent Limitations Pollutant or...

  1. The role of Cobalt-60 in modern radiation therapy: Dose delivery and image guidance

    Directory of Open Access Journals (Sweden)

    Schreiner L

    2009-01-01

    Full Text Available The advances in modern radiation therapy with techniques such as intensity-modulated radiation therapy and image-guid-ed radiation therapy (IMRT and IGRT have been limited almost exclusively to linear accel-erators. Investigations of modern Cobalt-60 (Co-60 radiation delivery in the context of IMRT and IGRT have been very sparse, and have been limited mainly to computer-modeling and treatment-planning exercises. In this paper, we report on the results of experiments using a tomotherapy benchtop apparatus attached to a conventional Co-60 unit. We show that conformal dose delivery is possible and also that Co-60 can be used as the radiation source in megavoltage computed tomography imaging. These results complement our modeling studies of Co-60 tomotherapy and provide a strong motivation for continuing development of modern Cobalt-60 treatment devices.

  2. Model studies of secondary hydrogenation in Fischer-Tropsch synthesis studied by cobalt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Aaserud, Christian

    2003-07-01

    Mass transfer effects are very important in Fischer-Tropsch (FT) synthesis. In order to study the FT synthesis without the influence of any transport limitations, cobalt foils have been used as model catalysts. The effect of pretreatment (number of calcinations and different reduction times) for cobalt foil catalysts at 220 {sup o}C, 1 bar and H{sub 2}/CO = 3 has been studied in a microreactor. The foils were examined by Scanning electron microscopy (SEM). It was found that the catalytic activity of the cobalt foil increases with the number of pretreatments possibly due to an increase in the surface area of the cobalt foil. The SEM results support the assumption that the surface area of the cobalt foil increases with the number of pretreatments. The reduction time was also found to influence the catalytic activity of the cobalt foil. Highest activity was obtained using a reduction time of only five min (compared to one and thirty min). The decrease in activity after reduction for thirty min compared to five min was suggested to be due to restructuring of the surface of the cobalt foil and a reduction time of only 1 min was not enough to reduce the cobalt foil sufficiently. Time of reduction did also influence the product distribution. Increased reduction time resulted in a lower selectivity to light products and increased selectivity to heavier components. The paraffin/olefin ratio increased with increasing CO-conversion also for cobalt foils. The paraffin/olefin ratio also increased when the reduction period of the cobalt foil was increased at a given CO-conversion. Hydrogenation of propene to propane has been studied as a model reaction for secondary hydrogenation of olefins in the FT synthesis. The study has involved promoted and unpromoted cobalt FT catalysts supported on different types of supports and also unsupported cobalt. Hydrogenation of propene was carried out at 120 {sup o}C, 1.8 bar and H{sub 2}/C{sub 3}H{sub 6} 6 in a fixed bed microreactor. The rate

  3. Effects of cobalt precursor on pyrolyzed carbon-supported cobalt-polypyrrole as electrocatalyst toward oxygen reduction reaction

    Science.gov (United States)

    Yuan, Xianxia; Hu, Xin-Xin; Ding, Xin-Long; Kong, Hai-Chuan; Sha, Hao-Dong; Lin, He; Wen, Wen; Shen, Guangxia; Guo, Zhi; Ma, Zi-Feng; Yang, Yong

    2013-11-01

    A series of non-precious metal electrocatalysts, namely pyrolyzed carbon-supported cobalt-polypyrrole, Co-PPy-TsOH/C, are synthesized with various cobalt precursors, including cobalt acetate, cobalt nitrate, cobalt oxalate, and cobalt chloride. The catalytic performance towards oxygen reduction reaction (ORR) is comparatively investigated with electrochemical techniques of cyclic voltammogram, rotating disk electrode and rotating ring-disk electrode. The results are analyzed and discussed employing physiochemical techniques of X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, elemental analysis, and extended X-ray absorption fine structure. It shows that the cobalt precursor plays an essential role on the synthesis process as well as microstructure and performance of the Co-PPy-TsOH/C catalysts towards ORR. Among the studied Co-PPy-TsOH/C catalysts, that prepared with cobalt acetate exhibits the best ORR performance. The crystallite/particle size of cobalt and its distribution as well as the graphitization degree of carbon in the catalyst greatly affects the catalytic performance of Co-PPy-TsOH/C towards ORR. Metallic cobalt is the main component in the active site in Co-PPy-TsOH/C for catalyzing ORR, but some other elements such as nitrogen are probably involved, too.

  4. Composition tunable cobalt-nickel and cobalt-iron alloy nanoparticles below 10 nm synthesized using acetonated cobalt carbonyl

    Energy Technology Data Exchange (ETDEWEB)

    Schooneveld, Matti M. van, E-mail: M.M.vanSchooneveld@gmail.com; Campos-Cuerva, Carlos; Pet, Jeroen; Meeldijk, Johannes D. [Utrecht University, Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science (Netherlands); Rijssel, Jos van [Utrecht University, Van' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science (Netherlands); Meijerink, Andries [Utrecht University, Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science (Netherlands); Erne, Ben H. [Utrecht University, Van' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science (Netherlands); Groot, Frank M. F. de, E-mail: F.M.F.deGroot@uu.nl [Utrecht University, Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science (Netherlands)

    2012-08-15

    A general organometallic route has been developed to synthesize Co{sub x}Ni{sub 1-x} and Co{sub x}Fe{sub 1-x} alloy nanoparticles with a fully tunable composition and a size of 4-10 nm with high yield. In contrast to previously reported synthesis methods using dicobalt octacarbonyl (Co{sub 2}(CO){sub 8}), here the cobalt-cobalt bond in the carbonyl complex is first broken with anhydrous acetone. The acetonated compound, in the presence of iron carbonyl or nickel acetylacetonate, is necessary to obtain small composition tunable alloys. This new route and insights will provide guidelines for the wet-chemical synthesis of yet unmade bimetallic alloy nanoparticles.

  5. INFLUENCE OF COBALT IONS ON ENZYME ACTIVTY OF ISOCITRIATE LYASE AND ITS REGULATION IN CONDITION OF SEED GERMINATION OF GLYCINE MAX L.

    Directory of Open Access Journals (Sweden)

    Chechui O. F.

    2012-12-01

    Full Text Available We investigated the activity of isocitrate lyase in seeds of Glycine max L. after 24, 72, and 120 hours of germination and effect of cobalt ions on the activity of the enzyme in time limit of the experiment. We fixed the increase in the activity of isocitrate lyase under influence of cobalt ions occurs by means of enzyme induction on third day of experiment while maintaining performance of enzyme activity on the fifth day; one of the reasons caused the increased activity of the key enzyme of the glyoxylate cycle under the influence of cobalt ions can be increasing of the concentration of lipid peroxidation. In addition, during experiments with usage of actinomycin D we determined the increasing of activity ofisocitrate lyase under the influence of cobalt ions by enzyme induction.

  6. Unipolar resistive switching in cobalt titanate thin films

    Science.gov (United States)

    Thakre, Atul; Shukla, A. K.; Katiyar, R. S.; Kumar, Ashok

    2017-02-01

    We report giant resistive switching of the order of 104, long-time charge retention characteristics up to 104 s, non-overlapping SET and RESET voltages, Ohmic in low-resistance state (LRS) and space charge limited current (SCLC) mechanism in high-resistance state (HRS) properties in polycrystalline perovskite cobalt titanate (\\text{CoTiO}3∼ \\text{CTO}) thin films. Impedance spectroscopy study was carried out for both LRS and HRS states which illustrates that only bulk resistance changes after resistance switching, however, there is a small change (<10% which is in the pF range) in the bulk capacitance value in both states. These results suggest that in the LRS state current filaments break the capacitor in many small capacitors in a parallel configuration which, in turn, provides the same capacitance in both states even if there was a 90-degree change in phase angle and an order of change in the tangent loss.

  7. Recovery of lithium and cobalt from waste lithium ion batteries of mobile phone

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Manis Kumar, E-mail: mkjha@nmlindia.org; Kumari, Anjan; Jha, Amrita Kumari; Kumar, Vinay; Hait, Jhumki; Pandey, Banshi Dhar

    2013-09-15

    Graphical abstract: Recovery of valuable metals from scrap batteries of mobile phone. - Highlights: • Recovery of Co and Li from spent LIBs was performed by hydrometallurgical route. • Under the optimum condition, 99.1% of lithium and 70.0% of cobalt were leached. • The mechanism of the dissolution of lithium and cobalt was studied. • Activation energy for lithium and cobalt were found to be 32.4 kJ/mol and 59.81 kJ/mol, respectively. • After metal recovery, residue was washed before disposal to the environment. - Abstract: In view of the stringent environmental regulations, availability of limited natural resources and ever increasing need of alternative energy critical elements, an environmental eco-friendly leaching process is reported for the recovery of lithium and cobalt from the cathode active materials of spent lithium-ion batteries of mobile phones. The experiments were carried out to optimize the process parameters for the recovery of lithium and cobalt by varying the concentration of leachant, pulp density, reductant volume and temperature. Leaching with 2 M sulfuric acid with the addition of 5% H{sub 2}O{sub 2} (v/v) at a pulp density of 100 g/L and 75 °C resulted in the recovery of 99.1% lithium and 70.0% cobalt in 60 min. H{sub 2}O{sub 2} in sulfuric acid solution acts as an effective reducing agent, which enhance the percentage leaching of metals. Leaching kinetics of lithium in sulfuric acid fitted well to the chemical controlled reaction model i.e. 1 − (1 − X){sup 1/3} = k{sub c}t. Leaching kinetics of cobalt fitted well to the model ‘ash diffusion control dense constant sizes spherical particles’ i.e. 1 − 3(1 − X){sup 2/3} + 2(1 − X) = k{sub c}t. Metals could subsequently be separated selectively from the leach liquor by solvent extraction process to produce their salts by crystallization process from the purified solution.

  8. Maintaining structural integrity of 4.5 V lithium cobalt oxide cathode with fumaronitrile as a novel electrolyte additive

    Science.gov (United States)

    Wang, Xianshu; Zheng, Xiongwen; Liao, Youhao; Huang, Qiming; Xing, Lidan; Xu, Mengqing; Li, Weishan

    2017-01-01

    The specific capacity of lithium-ion battery with lithium cobalt oxide as cathode depends on the upper limitation voltage for charge/discharge cycling, but this oxide tends to be destructed structurally when it is cycled in carbonate-based electrolyte under high voltage. We report a novel electrolyte additive, fumaronitrile (FN, CNsbnd CHdbnd CHsbnd CN), which can maintain the structural integrity of lithium cobalt oxide. Electrochemical measurements indicate that lithium cobalt oxide exhibits poor cyclic stability when it is cycled under 4.5 V (vs. Li/Li+) and the charged cathode suffers serious self-discharge in a base electrolyte, 1.0 mol L-1 LiPF6 in EC/EMC/DEC (3:5:2, by weight). These issues can be overcome effectively by adding 0.5% FN into the base electrolyte. Physical and chemical characterizations demonstrate that the poor cyclic stability and self-discharge of lithium cobalt oxide result from its structural destruction caused by HF formed from electrolyte decomposition, and FN yields a protective cathode interphase film which maintains the structural integrity of lithium cobalt oxide.

  9. Cobalt-Catalyzed [2π + 2π] Cycloadditions of Alkenes: Scope, Mechanism, and Elucidation of Electronic Structure of Catalytic Intermediates.

    Science.gov (United States)

    Schmidt, Valerie A; Hoyt, Jordan M; Margulieux, Grant W; Chirik, Paul J

    2015-06-24

    Aryl-substituted bis(imino)pyridine cobalt dinitrogen compounds, ((R)PDI)CoN2, are effective precatalysts for the intramolecular [2π + 2π] cycloaddition of α,ω-dienes to yield the corresponding bicyclo[3.2.0]heptane derivatives. The reactions proceed under mild thermal conditions with unactivated alkenes, tolerating both amine and ether functional groups. The overall second order rate law for the reaction, first order with respect to both the cobalt precatalyst and the substrate, in combination with electron paramagnetic resonance (EPR) spectroscopic studies established the catalyst resting state as dependent on the identity of the precatalyst and diene substrate. Planar S = ½ κ(3)-bis(imino)pyridine cobalt alkene and tetrahedral κ(2)-bis(imino)pyridine cobalt diene complexes were observed by EPR spectroscopy and in the latter case structurally characterized. The hemilabile chelate facilitates conversion of a principally ligand-based singly occupied molecular orbital (SOMO) in the cobalt dinitrogen and alkene compounds to a metal-based SOMO in the diene intermediates, promoting C-C bond-forming oxidative cyclization. Structure-activity relationships on bis(imino)pyridine substitution were also established with 2,4,6-tricyclopentyl-substituted aryl groups, resulting in optimized catalytic [2π + 2π] cycloaddition. The cyclopentyl groups provide a sufficiently open metal coordination sphere that encourages substrate coordination while remaining large enough to promote a challenging, turnover-limiting C(sp(3))-C(sp(3)) reductive elimination.

  10. Ascorbic Acid Assisted Synthesis of Cobalt Oxide Nanostructures, Their Electrochemical Sensing Application for the Sensitive Determination of Hydrazine

    Science.gov (United States)

    Tahira, Aneela; Nafady, Ayman; Baloach, Quarratulain; Sirajuddin; Sherazi, Syed Tufail Hussain; Shaikh, Tayyaba; Arain, Munazza; Willander, Magnus; Ibupoto, Zafar Hussain

    2016-07-01

    This study describes, the synthesis of cobalt oxide nanostructures using ascorbic acid as a growth directing agent by the hydrothermal method. Ascorbic acid is used for the first time for the synthesis of cobalt oxide nanostructures and a unique morphology is prepared in the present study. The cobalt oxide nanostructures were characterized by scanning electron microcopy, x-ray diffraction, and x-ray photoelectron spectroscopy techniques. These analytical techniques demonstrated well defined morphology, good crystalline quality, and high purity of as prepared cobalt oxide nanostructures. The glassy carbon electrode was modified with cobalt oxide nanostructures for the development of a sensitive and selective electrochemical hydrazine sensor. The developed hydrazine sensor exhibits a linear range of 2-24 μM. The sensitivity and limit of detection of presented hydrazine sensors are 12,734 μA/mM/cm2 and 0.1 μM respectively. The developed hydrazine sensor is highly selective, stable, and reproducible. The proposed sensor is successfully applied for the detection of hydrazine from different water samples. The present study provides the development of an alternative tool for the reliable monitoring of hydrazine from environmental and biological samples.

  11. Preparation of spherical cobalt carbonate powder with high tap density

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin; WANG Jian-feng; LIU Yong-dong; LI Jie; LIU Ye-xiang

    2006-01-01

    Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25 ± 0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.

  12. 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.

  13. 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.

  14. Cobalt-silica magnetic nanoparticles with functional surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vadala, Michael L. [Department of Chemistry and the Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Mail Code 0212, Blacksburg, VA 24061-0344 (United States); Zalich, Michael A. [School of Physics, The University of Western Australia, Crawley, WA 6009 (Australia); Fulks, David B. [Department of Chemistry and the Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Mail Code 0212, Blacksburg, VA 24061-0344 (United States); St Pierre, Tim G. [School of Physics, The University of Western Australia, Crawley, WA 6009 (Australia); Dailey, James P. [Department of Ophthalmology, Case Western Reserve University, Cleveland, OH (United States); Riffle, Judy S. [Department of Chemistry and the Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Mail Code 0212, Blacksburg, VA 24061-0344 (United States)]. E-mail: judyriffle@aol.com

    2005-05-15

    Cobalt nanoparticles encased in polysiloxane block copolymers have been heated at 600-700 deg C to form protective shells around the particles, which contain crosslinked Si-O structures, and to anneal the cobalt. Methods to functionalize and modify the surfaces of the pyrolyzed/annealed silica-cobalt complexes with amines, isocyanates, poly(ethylene oxide), poly(L-lactide) and polydimethylsiloxane (PDMS) are presented.

  15. 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

  16. 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.

  17. 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.

  18. Cobalt asthma in metalworkers from an automotive engine valve manufacturer.

    Science.gov (United States)

    Walters, G I; Robertson, A S; Moore, V C; Burge, P S

    2014-07-01

    Cobalt asthma has previously been described in cobalt production workers, diamond polishers and glassware manufacturers. To describe a case series of occupational asthma (OA) due to cobalt, identified at the Birmingham Heartlands Occupational Lung Disease Unit, West Midlands, UK. Cases of cobalt asthma from a West Midlands' manufacturer of automotive engine valves, diagnosed between 1996 and 2005, were identified from the SHIELD database of OA. Case note data on demographics, employment status, asthma symptoms and diagnostic tests, including spirometry, peak expiratory flow (PEF) measurements, skin prick testing (SPT) and specific inhalational challenge (SIC) tests to cobalt chloride, were gathered, and descriptive statistics used to illustrate the data. The natural history of presentations has been described in detail, as well as a case study of one of the affected workers. Fourteen metalworkers (86% male; mean age 44.9 years) were diagnosed with cobalt asthma between 1996 and 2005. Workers were principally stellite grinders, stellite welders or machine setter-operators. All workers had positive Occupational Asthma SYStem analyses of serial PEF measurements, and sensitization to cobalt chloride was demonstrated in nine workers, by SPT or SIC. We have described a series of 14 workers with cobalt asthma from the automotive manufacturing industry, with objective evidence for sensitization. Health care workers should remain vigilant for cobalt asthma in the automotive manufacturing industry. © The Author 2014. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. 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.

  20. Biocorrosion study of titanium-cobalt alloys.

    Science.gov (United States)

    Chern Lin, J H; Lo, S J; Ju, C P

    1995-05-01

    The present work provides experimental results of corrosion behaviour in Hank's physiological solution and some other properties of in-house fabricated titanium-cobalt alloys with cobalt ranging from 25-30% in weight. X-ray diffraction (XRD) shows that, in water-quenched (WQ) alloys, beta-titanium is largely retained, whereas in furnace-cooled (FC) alloys, little beta-titanium is found. Hardness of the alloys increases with increasing cobalt content, ranging from 455 VHN for WQ Ti-25 wt% Co to 525 VHN for WQ Ti-30 wt% Co. Differential thermal analysis (DTA) indicates that melting temperatures of the alloys are lower than that of pure titanium by about 600 degrees C. Potentiodynamic polarization results show that all measured break-down potentials in Hank's solution at 37 degrees C are higher than 800 mV. The breakdown potential for the FC Ti-25 Wt% Co alloy is even as high as nearly 1200 mV.

  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

    microscopy, X-ray photoemission spectroscopy (XPS) and valence band spectroscopy, and show that the cobalt oxidation state changes from Co2+ in bilayers to purely Co3+ in trilayers and a mixture of Co2+ and Co3+ in the multilayer morphology. In contrast to bilayers and multilayers, the trilayer structure...... 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...

  2. 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.

  3. Cobalt corrin catalyzed photoreduction of CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Grodkowski, J.; Neta, P.

    2000-03-09

    Cobalt corrins (B{sub 12}) are found to act as homogeneous catalysts for photoreduction of CO{sub 2} to CO and formic acid. Photoreduction is carried out in acetonitrile/methanol solutions containing p-terphenyl as a photosensitizer and triethylamine as a reductive quencher. Photolysis ({lambda} {ge} 300 nm) leads to production of CO and formic acid as well as H{sub 2}. The rate of production of all three products is considerably higher with the corrins (hydroxocobalamin, cyanocobalamin, and cobinamide) than with cobalt tetra-m-tolylporphyrin. The mechanism of CO{sub 2} reduction in all cases is via a species formed by one-electron reduction of the Co(I) complex. Radiolytic studies of the Co(I) complex formed from hydroxocobalamin in aqueous solutions show that this compound reacts very rapidly with solvated electrons and more slowly [k = (1.2 {+-} 0.3) x 10{sup 8} L mol{sup {minus}1}s{sup {minus}1}] with CO{sub 2}{sup {sm_bullet}{minus}} radicals to produce different products. The initial reduction product is suggested to be mainly the hydride formed by protonation of a Co(0) corrin, (HCoB{sub 12}){sup {minus}}, identical to the adduct formed by reaction of CO{sub 2} with the photochemically reduced Co(I) corrin, which proceeds to produce CO. H{sub 2} is formed by reaction of the hydride with a proton. Side reactions leading to hydrogenation of the macrocycle also take place and limit the catalytic activity.

  4. Magnetic transition phase diagram of cobalt clusters electrodeposited on HOPG: Experimental and micromagnetic modelling study

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, M., E-mail: mrivera@fisica.unam.m [Imperial College London, Department of Chemistry, South Kensington Campus, London SW7 2AZ (United Kingdom); Rios-Reyes, C.H. [Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Av. San Pablo 180, Col. Reynosa Tamaulipas, C.P. 02200, Mexico D.F. (Mexico); Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Mineral de la Reforma, Hidalgo, C.P. 42181 (Mexico); Mendoza-Huizar, L.H. [Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Mineral de la Reforma, Hidalgo, C.P. 42181 (Mexico)

    2011-04-15

    The magnetic transition from mono- to multidomain magnetic states of cobalt clusters electrodeposited on highly oriented pyrolytic graphite electrodes was studied experimentally using Magnetic Force Microscopy. From these images, it was found that the critical size of the magnetic transition is dominated by the height rather than the diameter of the aggregate. This experimental behavior was found to be consistent with a theoretical single-domain ferromagnetic model that states that a critical height limits the monodomain state. By analyzing the clusters magnetic states as a function of their dimensions, magnetic exchange constant and anisotropy value were obtained and used to calculate other magnetic properties such as the exchange length, magnetic wall thickness, etc. Finally, a micromagnetic simulation study correctly predicted the experimental magnetic transition phase diagram. - Research highlights: > Electrodeposition of cobalt clusters. > Mono to multidomain magnetic transition. > Magnetic phase diagram.

  5. Cobalt (hydro)oxide electrodes under electrochemical conditions: a first principle study

    Science.gov (United States)

    Chen, Jia; Selloni, Annabella

    2013-03-01

    There is currently much interest in photoelectrochemical water splitting as a promising pathway towards sustainable energy production. A major issue of such photoelectrochemical devices is the limited efficiency of the anode, where the oxygen evolution reaction (OER) takes place. Cobalt (hydro)oxides, particularly Co3O4 and Co(OH)2, have emerged as promising candidates for use as OER anode materials. Interestingly, recent in-situ Raman spectroscopy studies have shown that Co3O4 electrodes undergo progressive oxidation and transform into oxyhydroxide, CoO(OH), under electrochemical working conditions. (Journal of the American Chemical Society 133, 5587 (2011))Using first principle electronic structure calculations, we provide insight into these findings by presenting results on the structural, thermodynamic, and electronic properties of cobalt oxide, hydroxide and oxydroxide CoO(OH), and on their relative stabilities when in contact with water under external voltage.

  6. Application of rapid cloud point extraction method for trace cobalt analysis coupled with spectrophotometric determination.

    Science.gov (United States)

    Wen, Xiaodong; He, Lei; Shi, Chunsheng; Deng, Qingwen; Wang, Jiwei; Zhao, Xia

    2013-11-01

    In this work, the analytical performance of conventional spectrophotometer was improved through the coupling of effective preconcentration method with spectrophotometric determination. Rapidly synergistic cloud point extraction (RS-CPE) was used to pre-concentrate ultra trace cobalt and firstly coupled with spectrophotometric determination. The developed coupling was simple, rapid and efficient. The factors influencing RS-CPE and spectrophotometer were optimized. Under the optimal conditions, the limit of detection (LOD) was 0.6μgL(-1), with sensitivity enhancement factor of 23. The relative standard deviation (RSD) for seven replicate measurements of 50μgL(-1) of cobalt was 4.3%. The recoveries for the spiked samples were in the acceptable range of 93.8-105%.

  7. Application of rapid cloud point extraction method for trace cobalt analysis coupled with spectrophotometric determination

    Science.gov (United States)

    Wen, Xiaodong; He, Lei; Shi, Chunsheng; Deng, Qingwen; Wang, Jiwei; Zhao, Xia

    2013-11-01

    In this work, the analytical performance of conventional spectrophotometer was improved through the coupling of effective preconcentration method with spectrophotometric determination. Rapidly synergistic cloud point extraction (RS-CPE) was used to pre-concentrate ultra trace cobalt and firstly coupled with spectrophotometric determination. The developed coupling was simple, rapid and efficient. The factors influencing RS-CPE and spectrophotometer were optimized. Under the optimal conditions, the limit of detection (LOD) was 0.6 μg L-1, with sensitivity enhancement factor of 23. The relative standard deviation (RSD) for seven replicate measurements of 50 μg L-1 of cobalt was 4.3%. The recoveries for the spiked samples were in the acceptable range of 93.8-105%.

  8. A simple method for determining water content in organic solvents based on cobalt(II) complexes

    Institute of Scientific and Technical Information of China (English)

    Lin Zhou; Xiao Hua Liu; Hai Xin Bai; Hong Juan Wang

    2011-01-01

    A method to determine water content in organic solvents was developed based on the color change of cobalt(II) nitrate in different solvents. The color-change mechanism and optimal conditions for determining the water content were investigated. The results showed that there was a good linear relationships between the absorbance of cobalt(II) complexes in organic solvents and water contents with y in 0.9989~0.9994. This method has the advantages of low cost, good reproducibility, good sensitivity, simple in operation, fast in detection, friendly to the environment and no limitation on linear range for determining water content. It was used to determine water in samples with a satisfactory recovery in 97.81%~101.24%.

  9. 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....

  10. 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…

  11. Acetic acid assisted cobalt methanesulfonate catalysed chemoselective diacetylation of aldehydes

    Institute of Scientific and Technical Information of China (English)

    Min Wang; Zhi Guo Song; Hong Gong; Heng Jiang

    2008-01-01

    Cobalt methanesulfonate in combination with acetic acid catalysed the chemoselective diacetylation of aldehyde with acetic anhydride at room temperature under solvent free conditions. After reaction, cobalt methanesulfonate can be easily recovered and mused many times. The reaction was mild and efficient with good to high yields.

  12. Hepatic Cobalt and Copper Levels in Lambs in Norway

    OpenAIRE

    Plassen C; Sivertsen T

    2004-01-01

    Cobalt and copper concentrations were measured in 599 lamb livers collected at slaughter from 58 sheep flocks in 6 different parts of Norway in 1993. Information about pasture, additional feeding and mineral supplements in the flocks was obtained through a questionnaire. Average hepatic levels of cobalt in the lamb flocks varied from

  13. 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 ...

  14. 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.

  15. 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…

  16. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation

    Science.gov (United States)

    Majtan, Tomas; Frerman, Frank E.

    2011-01-01

    Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound cytochromes and an expressed human cystathionine beta-synthase (CBS). The presence of CoPPIX in cytochromes inhibited their electron transport capacity and resulted in a substantially decreased respiration. Bacterial cells adapted to the increased cobalt concentration by inducing a modified mixed acid fermentative pathway under aerobiosis. We capitalized on the ability of E. coli to insert cobalt into PPIX to carry out an expression of CoPPIX-substituted heme proteins. The level of CoPPIX-substitution increased with the number of passages of cells in a cobalt-containing medium. This approach is an inexpensive method to prepare cobalt-substituted heme proteins compared to in vitro enzyme reconstitution or in vivo replacement using metalloporphyrin heme analogs and seems to be especially suitable for complex heme proteins with an additional coenzyme, such as human CBS. PMID:21184140

  17. Metal Organic Chemical Vapour Deposited Thin Films of Cobalt Oxide Prepared via Cobalt Acetylacetonate

    Institute of Scientific and Technical Information of China (English)

    C.U. Mordi; M.A. Eleruja; B.A. Taleatu; G.O. Egharevba; A.V. Adedeji; 0.0. Akinwunmi; B. Olofinjana; C. Jeynes; E.O.B. Ajayi

    2009-01-01

    The single solid source precursor, cobalt (Ⅱ) acetylacetonate was prepared and characterized by infrared spec-troscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis (metal organic chemical vapour deposition (MOCVD)) of single solid source precursor, cobalt acetylaceto-nate, Co[C5H7O2]2 at a temperature of 420℃. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction (XRD), showed that the films have a stoichiometry of Co2O3 and an average thickness of 227±0.2 nm. A direct energy gap of 2.15±0.01 eV was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron mi-croscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than 1 micron for the deposited thin films of cobalt oxide.

  18. 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 acti

  19. Non-Collinearity in Small Magnetic Cobalt-Benzene Molecules

    CERN Document Server

    González, J W; Delgado, F; Aguilera-Granja, F; Ayuela, A

    2016-01-01

    Cobalt clusters covered with benzene in the form of rice-ball structures have recently been synthesized using laser ablation. Here, we investigate the types of magnetic order such clusters have, and whether they retain any magnetic order at all. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings. We found that the benzene rings induce a ground state with non-collinear magnetization, with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms. This is surprising because nanostructures and small clusters based on pure cobalt typically have a predominantly ferromagnetic order, and additional organic ligands such as benzene tend to remove the magnetization. We analyze the magnetism of such a cluster using an anisotropic Heisenberg model where the involved parameters are obtained by a comparison with the DFT results. Moreover, we propose electron paramagnetic resonance as ...

  20. 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.

  1. 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....... MATERIALS AND METHODS: The cobalt spot test, X-ray fluorescence, inductively coupled plasma mass spectrometry and scanning electron microscopy were used to determine cobalt content and release from the leather couch that caused the dermatitis and from 14 randomly collected samples of furniture leather....... RESULTS: The sample from the patient's leather couch, but none of the 14 random leather samples, released cobalt in high concentrations. Dermatitis cleared when the patient stopped using his couch. CONCLUSIONS: Cobalt is used in the so-called pre-metallized dyeing of leather products. Repeated studies...

  2. Microemulsion-mediated synthesis of cobalt (pure fcc and hexagonal phases) and cobalt-nickel alloy nanoparticles.

    Science.gov (United States)

    Ahmed, Jahangeer; Sharma, Shudhanshu; Ramanujachary, Kandalam V; Lofland, Samuel E; Ganguli, Ashok K

    2009-08-15

    By choosing appropriate microemulsion systems, hexagonal cobalt (Co) and cobalt-nickel (1:1) alloy nanoparticles have been obtained with cetyltrimethylammonium bromide as a cationic surfactant at 500 degrees C. This method thus stabilizes the hcp cobalt even at sizes (fcc cobalt is predicted to be stable. On annealing the hcp cobalt nanoparticles in H(2) at 700 degrees C we could transform them to fcc cobalt nanoparticles. Microscopy studies show the formation of spherical nanoparticles of hexagonal and cubic forms of cobalt and Co-Ni (1:1) alloy nanoparticles with the average size of 4, 8 and 20 nm, respectively. Electrochemical studies show that the catalytic property towards oxygen evolution is dependent on the applied voltage. At low voltage (less than 0.65 V) the Co (hexagonal) nanoparticles are superior to the alloy (Co-Ni) nanoparticles while above this voltage the alloy nanoparticles are more efficient catalysts. The nanoparticles of cobalt (hcp and fcc) and alloy (Co-Ni) nanoparticles show ferromagnetism. The saturation magnetization of Co-Ni nanoparticles is reduced compared to the bulk possibly due to surface oxidation.

  3. 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.

  4. 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.

  5. 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

    2017-03-21

    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.

  6. 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...

  7. Atomically flat ultrathin cobalt ferrite islands.

    Science.gov (United States)

    Martín-García, Laura; Quesada, Adrián; Munuera, Carmen; Fernández, Jose F; García-Hernández, Mar; Foerster, Michael; Aballe, Lucía; de la Figuera, Juan

    2015-10-21

    A route for fabricating structurally perfect cobalt ferrite magnetic nanostructures is demonstrated. Ultrathin islands of up to 100 μm(2) with atomically flat surfaces and free from antiphase boundaries are developed. The extremely low defect concentration leads to a robust magnetic order, even for thicknesses below 1 nm, and exceptionally large magnetic domains. This approach allows the evaluation of the influence of specific extrinsic effects on domain wall pinning. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 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.

  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. 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.

  11. Heat Transport of Electron-Doped Cobaltates

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; LIANG Ying; FENG Shi-Ping; CHEN Wei-Yeu

    2006-01-01

    Within the t-J model, the heat transport of electron-doped cobaltates is studied based on the fermionspin theory. It is shown that the temperature-dependent thermal conductivity is characterized by the low-temperature peak located at a finite temperature. The thermal conductivity increases monotonously with increasing temperature at low-temperatures T < 0.1 J, and then decreases with increasing temperature for higher temperatures T > 0.1 J, in qualitative agreement with experimental result observed from NaxCoO2.

  12. 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.

  13. 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

    BACKGROUND: 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. METHODS: 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). 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...

  14. Supply and Demand Situation in Domestic Cobalt Industry May Come to a Turning Point

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    Multiple factors overlapped to bring opportunity to the cobalt business unit:Three factors of"Shrinking Supply"+"Growing Demand"+"Price Bottom"overlap to change market’s future expectation for cobalt products.As a big power of cobalt refining and cobalt consumption,China received obvious impact,relevant enterprises mainly include Huayou Cobalt,China Molybdenum,and GEM.

  15. 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.)

  16. 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.

  17. Cobalt Deposits in the Central China Orogenic Belt

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Cobalt mostly occurs as an associated metal in Cu-Ni sulphide deposits, skarn Fe-Cu-Pb-Zn deposits and volcanic-hosted massive sulphide (VHMS) or sedex deposits. There are different types of cobalt deposits in the Central China orogenic belt. In the Tamu-Kalangu Mississippi-valley type Pb-Zn deposits, many cobalt-nickel sulphide minerals were found. The cobalt content of the ore is 0.064%- 0.46% in sedex-type Kendekeke Fe-Pb-Zn-Au deposits, and cobalt sulphide veins with Co contents of 4%- 9% have also been found. About 28000 tons of cobalt reserves were delineated in the Durgoi Cu-Co-Zn deposit of VHMS type in the A'nyemaqên Mountains. It is considered that the exploration potential for cobalt is attractive in this district, especially in sedex-type deposits and Co-rich sulphide veins in sedex-type Fe, Cu and Pb-Zn deposits and their surroundings.

  18. Preparation of cobalt-modified magnetite and its magnetic properties

    Institute of Scientific and Technical Information of China (English)

    YANG Xi-yun; GONG Zhu-qing; LIU Feng-liang; HUANG Jian

    2005-01-01

    Magnetite was modified by reaction with alkaline solution containing Co2+ and Fe2+ to obtain a cobalt ferrite layer on the surface of particles.The influences of modification conditions on the properties were investigated.The as-prepared particles were characterized by X-ray diffraction(XRD)and transmission electron microscope(TEM).The results show that pH value influences the particles composition directly,the desirable CoFe2O4 is obtained as pH value is 12.The coercivity of particles increases with the increase of cobalt content,and the cobalt efficiency reaches a maximum value at cobalt content of 2.71%(mass fraction).With cobalt modification,the magnetite particles have the similar lattice constant and structure to that without cobalt modification,and the squareness ratio is almost 0.5.The increase of the coercivity is attributed to the uniaxial magnetic anisotropy and magnetocrystalline anisotropy of cobalt-ferrite itself.

  19. Production of cobalt and nickel particles by hydrogen reduction

    Science.gov (United States)

    Forsman, J.; Tapper, U.; Auvinen, A.; Jokiniemi, J.

    2008-05-01

    Cobalt and nickel nanoparticles were produced by hydrogen reduction reaction from cobalt or nickel chloride precursor vapour in nitrogen carrier gas. This aerosol phase method to produce nanoparticles is a scalable one-step process. Two different setups were introduced in particle production: a batch type reactor and a continuously operated reactor. Common feature in these setups was hydrogen mixing in a vertical flow reactor. The process was monitored on-line for particle mass concentration and for gas phase chemical reactions. Tapered element oscillating microbalance measured the particle mass concentration and Fourier transform infrared spectroscopy was used to monitor relevant gas phase species. The produced cobalt and nickel particles were characterised using transmission electron microscopy and x-ray diffraction. The produced cobalt and nickel particles were crystalline with cubic fcc structure. Twinning was often observed in cobalt particles while nickel particles were mostly single crystals. The cobalt particles formed typically long agglomerates. No significant neck growth between the primary particles was observed. The primary particle size for cobalt and nickel was below 100 nm.

  20. Dysprosium Modification of Cobalt Ferrite Ionic Magnetic Fluids

    Institute of Scientific and Technical Information of China (English)

    JIANG Rong-li; LIU Yong-chao; GENG Quan-rong; ZHAO Wen-tao

    2005-01-01

    Dysprosium composite cobalt ferrite ionic magnetic fluids were prepared by precipitation in the presence of Tri-sodium citrate. Influence of dysprosium modification on magnetic property is studied. The result shows that magnetic response toward exterior magnetic field can be improved by adding Dy3+. Studies also show that the increase of reaction temperature may improve the modification effect of dysprosium. By adding dysprosium ions, the average diameter of the magnetic nanoparticles will be decreased evidently. It is clear that the particles appear as balls, Cobalt ferrite with sizes of 12-15 nm, rare earth composite cobalt ferrite with sizes of 6-8 nm.

  1. Photoluminescence quenching in cobalt doped ZnO nanocrystals

    OpenAIRE

    Sekika Yamamoto

    2012-01-01

    Influence of cobalt doping on the luminescence properties of ZnO nanocrystals with average diameter of 3.0 nm is investigated. Time resolved measurements at 20 K show that the dark exciton luminescence is completely lost in the nanocrystals doped with cobalt, while the perturbed luminescence with slight red shift survives and exhibits a non-exponential decay curve reflecting random distribution of cobalt atoms. By analyzing the non-exponentiality, the increase of the decay rate of the band-ed...

  2. Divergent Reactivity via Cobalt Catalysis: An Epoxide Olefination.

    Science.gov (United States)

    Jamieson, Megan L; Hume, Paul A; Furkert, Daniel P; Brimble, Margaret A

    2016-02-05

    Cobalt salts exert an unexpected and profound influence on the reactivity of epoxides with dimethylsulfoxonium methylide. In the presence of a cobalt catalyst, conditions for epoxide to an oxetane ring expansion instead deliver homoallylic alcohol products, corresponding to a two-carbon epoxide homologation/ring-opening tandem process. The observed reactivity change appears to be specifically due to cobalt salts and is broadly applicable to a variety of epoxides, retaining the initial stereochemistry. This transformation also provides operationally simple access to enantiopure homoallylic alcohols from chiral epoxides without use of organometallic reagents. Tandem epoxidation-homologation of aldehydes in a single step is also demonstrated.

  3. 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.

  4. Cobalt catalysis involving π components in organic synthesis.

    Science.gov (United States)

    Gandeepan, Parthasarathy; Cheng, Chien-Hong

    2015-04-21

    Over the last three decades, transition-metal-catalyzed organic transformations have been shown to be extremely important in organic synthesis. However, most of the successful reactions are associated with noble metals, which are generally toxic, expensive, and less abundant. Therefore, we have focused on catalysis using the abundant first-row transition metals, specifically cobalt. In this Account, we demonstrate the potential of cobalt catalysis in organic synthesis as revealed by our research. We have developed many useful catalytic systems using cobalt complexes. Overall, they can be classified into several broad types of reactions, specifically [2 + 2 + 2] and [2 + 2] cycloadditions; enyne reductive coupling; reductive [3 + 2] cycloaddition of alkynes/allenes with enones; reductive coupling of alkyl iodides with alkenes; addition of organoboronic acids to alkynes, alkenes, or aldehydes; carbocyclization of o-iodoaryl ketones/aldehydes with alkynes/electron-deficient alkenes; coupling of thiols with aryl and alkyl halides; enyne coupling; and C-H bond activation. Reactions relying on π components, specifically cycloaddition, reductive coupling, and enyne coupling, mostly afford products with excellent stereo- and regioselectivity and superior atom economy. We believe that these cobalt-catalyzed π-component coupling reactions proceed through five-membered cobaltacyclic intermediates formed by the oxidative cyclometalation of two coordinated π bonds of the substrates to the low-valent cobalt species. The high regio- and stereoselectivity of these reactions are achieved as a result of the electronic and steric effects of the π components. Mostly, electron-withdrawing groups and bulkier groups attached to the π bonds prefer to be placed near the cobalt center of the cobaltacycle. Most of these transformations proceed through low-valent cobalt complexes, which are conveniently generated in situ from air-stable Co(II) salts by Zn- or Mn-mediated reduction

  5. Cobalt(III) Chaperone Complexes of Curcumin: Photoreduction, Cellular Accumulation and Light-Selective Toxicity towards Tumour Cells.

    Science.gov (United States)

    Renfrew, Anna K; Bryce, Nicole S; Hambley, Trevor

    2015-10-19

    Light-activated prodrugs offer the potential for highly selective tumour targeting. However, the application of many photoactivated chemotherapeutics is limited by a requirement for oxygen, or for short activation wavelengths that can damage surrounding tissue. Herein, we present a series of cobalt(III)-curcumin prodrugs that can be activated by visible light under both oxygenated and hypoxic conditions. Furthermore, the photoproduct can be controlled by the activation wavelength: green light yields free curcumin, whereas blue light induces photolysis of curcumin to a phototoxic product. Confocal fluorescence microscopy and phototocytotoxicity studies in DLD-1 and MCF-7 tumour cells demonstrated that the cobalt(III) prodrugs are nontoxic in the dark but accumulate in significant concentrations in the cell membrane. When cells were treated with light for 15  min, the cytotoxicity of the cobalt complexes increased by up to 20-fold, whereas free curcumin exhibited only a two-fold increase in cytotoxicity. The nature of the ancillary ligand and cobalt reduction potential were found to strongly influence the stability and biological activity of the series. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. 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.)

  7. Cobalt-based particles formed upon electrocatalytic hydrogen production by a cobalt pyridine oxime complex.

    Science.gov (United States)

    Ghachtouli, Sanae El; Guillot, Regis; Brisset, Francois; Aukauloo, Ally

    2013-12-01

    An open-coordination-sphere cobalt(III) oximato-based complex was designed as a putative catalyst for the hydrogen evolution reaction (HER). Electrochemical alteration in the presence of acid occurs, leading to the formation of cobalt-based particles that act as an efficient catalyst for HER at pH 7. The exact chemical nature of these particles is yet to be determined. This study thus raises interesting issues regarding the fate of molecular-based complexes designed for the HER, and points to the challenging task of identifying the real catalytic species. Moreover, understanding and rationalizing the alteration pathways can be seen as a new route to reach catalytic particulates.

  8. The influence of cobalt-coordination on cobalt-mediated radical polymerization of vinyl monomers

    OpenAIRE

    2009-01-01

    Nowadays, polymers are a part of everyday life. Researchers encouraged by growing need in high performance polymers develop new synthesis tools to manage the molecular architecture and thus the polymer properties. In this context, CRP (Controlled Radical Polymerization) techniques have been developed to obtain well-defined architectures and to control polymer parameters. Among these systems is Cobalt-Mediated Radical Polymerization (CMRP), which is based on the reversible deactivation of the ...

  9. 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.

  10. 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.)

  11. 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.

  12. PURIFICATION OF COBALT ANOLYTE USING THE NOVEL SOLVENT EXTRACTION SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Y.F. Shen; W.Y. Xue; W. Y. Niu

    2003-01-01

    In present research, a novel extractant system (D2EHPA + naphthenic acid +pyridine-ester) was used to purify cobalt anolyte and a simulated industrial produc-tion were carried out. This novel extraction system can extract Cu and/or Ni againstCo from chloride medium solutions at pH range of 2.5-4.5. About 2g/l nickel and0.2g/l copper were removed from the cobalt chloride anolyte containing about 100g/lcobalt and 200g/l chloride ions respectively, the raffinate contains nickel and copperless than 0.03g/l and 0. 0003g/l respectively and can be used to electrolyze high-puritycobalt. About 5.5t cobalt anolyte was purified in the simulation industrial experimentand kilogram quantities of cobalt of 99.98% purity and about 95% recovery have beenproduced.

  13. Formation of cobalt silicide by ion beam mixing

    Science.gov (United States)

    Min, Ye; Burte, Edmund P.; Ryssel, Heiner

    1991-07-01

    The formation of cobalt silicides by arsenic ion implantation through a cobalt film which causes a mixing of the metal with the silicon substrate was investigated. Furthermore, cobalt suicides were formed by rapid thermal annealing (RTA). Sheet resistance and silicide phases of implanted Co/Si samples depend on the As dose. Ion beam mixing at doses higher than 5 × 10 15 cm -2 and RTA at temperatures T ⩾ 900° C result in almost equal values of Rs. RBS and XRD spectra of these samples illustrate the formation of a homogeneous CoSi 2 layer. Significant lateral growth of cobalt silicide beyond the edge of patterned SiO 2 was observed in samples which were only subjected to an RTA process ( T ⩾ 900 ° C), while this lateral suicide growth could be reduced efficiently by As implantation prior to RTA.

  14. Kondo-effect of substitutional cobalt impurities at copper surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, P; Diekhoener, L; Schneider, M A; Kern, K [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany); Seitsonen, A P [IMPMC, CNRS and Universite Pierre et Marie Curie, 4 Place Jussieu, Case 115, F-75252 Paris (France)], E-mail: wahl@fkf.mpg.de

    2009-11-15

    The influence of the coordination on the Kondo temperature of a magnetic impurity at a noble metal surface and the line shape observed in low temperature scanning tunneling spectroscopy (STS) is investigated for single cobalt atoms adsorbed on and embedded in copper surfaces. Surprisingly, the Kondo temperature for substitutional cobalt atoms is almost the same as that of adatoms on the Cu(100) surface. This is in stark contrast to the behaviour observed at the Cu(111) surface. DFT calculations reveal that in the case of Cu(100) the coupling of the spin of the cobalt atom to the conduction band is not substantially increased by the incorporation of the cobalt atom. At the same time the observed line shape differs strongly from what is observed on adatom systems.

  15. An Alternate to Cobalt-Base Hardfacing Alloys

    Science.gov (United States)

    Hickl, Anthony J.

    1980-03-01

    The price of cobalt has risen dramatically in the last few years, and supply has often been uncertain. The most popular hardfacing alloys contain substantial amounts of cobalt, and have thus been especially affected by these factors. The present study has developed a new hardfacing alloy, HAYNES Alloy No. 716, with lower cobalt content, to replace the most popular alloy, HAYNES STELLITE Alloy No. 6 which is cobalt based. The alloy design which led to the development of the new alloy is discussed, and properties are compared with Alloy No. 6. Hardness at room temperature and elevated temperatures, weldability, and corrosion and abrasion resistance of the new alloy compare favorably with Alloy No. 6.

  16. Alumina Template-Dependant Growth of Cobalt Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    L. Malferrari

    2009-01-01

    Full Text Available Different electrochemical regimes and porous alumina were applied for template synthesis of cobalt nanowire (nw arrays, revealing several peculiar cases. In contrast to quite uniform filling of sulfuric acid alumina templates by alternating current deposition, nonuniform growth of the Co nw tufts and mushrooms was obtained for the case of oxalic acid templates. We showed herein for the first time that such configurations arise from the spontaneous growth of cobalt nw groups evolving from the cobalt balls at the Al/alumina interface. Nevertheless, the uniform growth of densely packed cobalt nw arrays, up to tens of micrometers in length, was obtained via long-term direct current galvanostatic deposition at low current density using oxalic acid templates one-side coated by conducting layer. The unique point of this regime is the formation of hexagonal lattice Co nws with a preferred (100 growth direction.

  17. Electron transport properties of cobalt doped polyaniline

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, P [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Sarkar, A [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Meikap, A K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Chattopadhyay, S K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Chatterjee, S K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Ghosh, M [Department of Physics, Ramananda College, Bishnupur, Bankura-722 122, West Bengal (India)

    2006-07-21

    Electrical transport properties of cobalt doped polyaniline in an aqueous ethanol medium were investigated in the temperature range 77 {<=} T {<=} 300 K, applying magnetic fields up to 1 T in the frequency range 20 Hz-1 MHz. The room temperature dc resistivity increases with increase in Co content. The dc resistivity and magnetoresistivity of these samples have been interpreted in terms of the variable range hopping theory. The frequency dependence of conductivity has been described by a power law {sigma}({omega}) {approx} {omega}{sup S}. The value of s is found to be temperature dependent, which shows a decreasing trend with temperature. The correlated barrier hopping model is the most likely mechanism for the electron transport. The different physical parameters were calculated from the experimental data.

  18. Cobalt and antimony: genotoxicity and carcinogenicity.

    Science.gov (United States)

    De Boeck, Marlies; Kirsch-Volders, Micheline; Lison, Dominique

    2003-12-10

    The purpose of this review is to summarise the data concerning genotoxicity and carcinogenicity of Co and Sb. Both metals have multiple industrial and/or therapeutical applications, depending on the considered species. Cobalt is used for the production of alloys and hard metal (cemented carbide), diamond polishing, drying agents, pigments and catalysts. Occupational exposure to cobalt may result in adverse health effects in different organs or tissues. Antimony trioxide is primarily used as a flame retardant in rubber, plastics, pigments, adhesives, textiles, and paper. Antimony potassium tartrate has been used worldwide as an anti-shistosomal drug. Pentavalent antimony compounds have been used for the treatment of leishmaniasis. Co(II) ions are genotoxic in vitro and in vivo, and carcinogenic in rodents. Co metal is genotoxic in vitro. Hard metal dust, of which occupational exposure is linked to an increased lung cancer risk, is proven to be genotoxic in vitro and in vivo. Possibly, production of active oxygen species and/or DNA repair inhibition are mechanisms involved. Given the recently provided proof for in vitro and in vivo genotoxic potential of hard metal dust, the mechanistic evidence of elevated production of active oxygen species and the epidemiological data on increased cancer risk, it may be advisable to consider the possibility of a new evaluation by IARC. Both trivalent and pentavalent antimony compounds are generally negative in non-mammalian genotoxicity tests, while mammalian test systems usually give positive results for Sb(III) and negative results for Sb(V) compounds. Assessment of the in vivo potential of Sb2O3 to induce chromosome aberrations (CA) gave conflicting results. Animal carcinogenicity data were concluded sufficient for Sb2O3 by IARC. Human carcinogenicity data is difficult to evaluate given the frequent co-exposure to arsenic. Possible mechanisms of action, including potential to produce active oxygen species and to interfere with

  19. Use of phosphate for separation of cobalt from iron

    Science.gov (United States)

    North, V.; Wells, R.C.

    1942-01-01

    The well-known tendency of cobalt to be retained by the iron-alumina precipitate produced by ammonia has generally been ascribed to a specific adsorption by the large surface of this gelatinous precipitate. Whatever its cause, it can be overcome by precipitating the iron as phosphate at a pH of 3.5. The precipitate is easily filterable and practically all the cobalt passes into the filtrate.

  20. 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.

  1. 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.

  2. Identification of Different Cobalt Nucleation on Glassy Carbon

    Institute of Scientific and Technical Information of China (English)

    Min GU; Fang Zu YANG; Ling HUANG; Shi Bing YAO; Shao Min ZHOU

    2004-01-01

    The nucleation mechanisms of cobalt from sulfate solutions were studied by utilizing the electrochemical technique, chronoamperometry.It was found that the recorded current-time transients introduced from 1.0 mol/L CoSO4 solution were complexes with unusual shapes.All characteristic features were identified as separate process.The instantaneous or progressive nucleation with 2D or 3D growth exists during the cobalt deposition, depending on the applied potentials.

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

    Science.gov (United States)

    Asha, Goyal, Sneh Lata; Kishore, Nawal

    2016-05-01

    Polyaniline (PANI) and PANI /cobalt chloride composites were synthesized by in situ chemical oxidative polymerization of aniline with CoCl2.6H2O 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.

  4. Monte Carlo study of MLC fields for cobalt therapy machine

    Science.gov (United States)

    Ayyangar, Komanduri M.; Rani, Roopa A.; Kumar, Anil; Reddy, A. R.

    2014-01-01

    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 cm2 to 14 × 14 cm2 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 cm2 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. †Radiation Oncology Planning System (ROPS) is supplied by Tirumala Jyothi Computer Systems described at https

  5. Cobalt Deposits of China:Classification, Distribution and Major Advances

    Institute of Scientific and Technical Information of China (English)

    FENG Chengyou; ZHANG Dequan

    2004-01-01

    The important strategic metal cobalt has diverse uses and the majority of world cobalt deposits have been found in China. The deposits can be classified into four types, i.e., magmatic Ni-Cu-Co sulfide deposits, hydrothermal and volcanogenic cobalt polymetallic deposits, strata-bound Cu-Co deposits hosted by sedimentary rocks and lateritic Ni-Co deposits, of which the former two types are the most important. There are six principal metallogenic epochs and seven important metallogenic belts according to their distribution and tectonic position. Although cobalt generally occurs in nickel-copper, copper and iron deposits as an associated metal, great developments in exploration for independent cobalt deposits have happened in China, and, in recent years, many independent deposits with different elementary assemblages and different genetic types have been discovered in the eastem part of the northern margin of the North China platform, the Central Orogenic Belt of China, western Jiangxi and northeastern Hunan. In addition, it is inferred that the Kunlun-Qinling Orogenic Belt has great potential for further exploration of new types of independent cobalt deposits.

  6. The biokinetics of inorganic cobalt in the human body.

    Science.gov (United States)

    Leggett, R W

    2008-01-25

    This paper reviews information on the biological behavior of inorganic cobalt in humans and laboratory animals and proposes a model of the systemic biokinetics of inorganic cobalt in adult humans. The model was developed as part of an effort to update the models of the International Commission on Radiological Protection (ICRP) for addressing intakes of radionuclides by workers but is also applicable to environmental or medical exposures to inorganic forms of radiocobalt. The model can be used in conjunction with any respiratory, gastrointestinal, or wound model that provides predictions of the time-dependent feed of cobalt to blood. In contrast to the ICRP's current systemic model for cobalt, which is a simple open catenary system, the proposed model is constructed within a physiologically realistic framework that depicts recycling of cobalt between blood and tissues and transfer from blood to excretion pathways. Compared with the ICRP's current model, the proposed model yields similar predictions of whole-body retention but substantially different predictions of the systemic distribution of cobalt as a function of time after uptake to blood.

  7. Characteristics of cobalt removal by crab shell particles

    Energy Technology Data Exchange (ETDEWEB)

    Lee, MooYeal; Kajiuchi, Toshio [Department of International Development, Tokyi Institute of Technology, Tokyo (Korea, Republic of); Kang, Hyun Ah; Yang, Ji Won [Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1999-07-01

    The characteristics of cobalt removal by raw crab shell particles was investigated. The removal efficiency of cobalt was dependent on contact time, solution pH, crab shell dose and ionic strength. Approximately 99% of the cobalt was removed within 6 hour after contact with crab shell particles. The removal efficiency was slightly affected by initial solution pH over 5.0 and the final solution pH changed to 10 spontaneously. In addition, optimum pH range of cobalt removal was broaden by the effect of crab shell addition. Maximum uptake of cobalt was 510 mg Co/g crab shell at initial pH 5.0. The removal efficiency was affected slightly by ionic strength up to 2.0 M of NaCl. From the results of scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), the removal of cobalt by crab shell was mainly through the dissolution of CaCO{sub 3} followed by precipitation of Co(OH){sub 2} and CoCO{sub 3} and then the precipitates were adsorbed to the chitin on the surface of crab shell particles. Compared to the results with activated carbon column, the addition of crab shell to activated carbon column increased the removal efficiency dramatically.(author)

  8. A highly selective and sensitive fluorescence assay for determination of copper(II) and cobalt(II) ions in environmental water and toner samples.

    Science.gov (United States)

    Tsai, Chia-Yi; Lin, Yang-Wei

    2013-02-21

    In this study, a highly selective and sensitive fluorescence assay has been proposed for the determination of copper(II) and cobalt(II) ions in environmental water and toner samples. In the presence of hydrogen peroxide, copper(II) reacted with a new fluorescence reagent Amplex® UltraRed (AUR), forming a fluorescence product only at pH 7.0, while the fluorescence product of cobalt(II) with AUR formed only at pH 9.0. The fluorescence signal obtained was linear with respect to the copper(II) concentration over the range of 1.6-12.0 μM (R(2) = 0.988) and was linear with respect to the cobalt(II) concentration over the range of 45.0 nM to 1.0 μM (R(2) = 0.992). The limits of detection (at a signal-to-noise ratio of 3) for copper(II) and cobalt(II) were 0.17 μM and 14.0 nM, respectively. Our present approach is simpler, faster, and more cost-effective than other techniques for the detection of copper(II) and cobalt(II) ions in environmental water samples and that of copper(II) ions in toner samples.

  9. 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.

  10. 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.

  11. Determination of cobalt in biological samples by electrothermal atomic absorption spectrometry after extraction with 1,5-bis (di-2-pyridylmethylene) thiocarbohydrazide

    Energy Technology Data Exchange (ETDEWEB)

    Collado, G.; Bosch Ojeda, C.; Garcia de Torres, A.; Cano Pavon, J.M. [University of Malaga (Spain)

    1995-06-01

    A method for the determination of trace amounts of cobalt in biological samples by atomic absorption spectrometry with graphite furnace atomization extraction conditions were evaluated from a critical study of the effects of pH, concentration of extractant, shaking time and ionic strength. The detection limit for cobalt is 0.06 ng ml{sup -1} and the calibration is linear from 0.1 to 2.5 ng ml{sup -1}. The relative standard deviation for ten replicate measurements is 1.7 % for 0.5 ng ml{sup -1} of cobalt. The effect of interferences was studied and no interferences from the elements commonly found in biological materials were observed. The chief advantage of the method lies in its maximum allowable aqueous-to-organic phase volume ratio of 30:1. Results from the analysis of some certified biological reference materials are given. (authors). 14 refs., 1 figs., 3 tabs.

  12. Cobalt uptake and binding in human red blood cells.

    Science.gov (United States)

    Simonsen, Lars Ole; Brown, Anthony M; Harbak, Henrik; Kristensen, Berit I; Bennekou, Poul

    2011-04-15

    The basal uptake and cytoplasmic binding of cobalt was studied in human red cells using (57)Co as tracer. The basal uptake is linear with time, at a rate of about 10 μmol (l cells)(-1) h(-1) at 100 μM [Co(2+)](o), and is almost irreversible, as there is hardly any efflux into excess EDTA. Ionophore A23187 mediates a rapid equilibration of Co(2+) across the cell membrane leading to a marked accumulation, reflecting effective cytoplasmic buffering. The fraction (α(Co)) of total cell cobalt being present as free, ionized Co(2+) is estimated at α(Co)=0.01 from the equilibrium distribution of cobalt, and also from the initial slope of the cobalt buffering curve. The cobalt accumulation is similar in fed and ATP-depleted cells. The buffering curve for [Co(T)](c) can be fitted by a Michaelis type function with B(max)=24 mmol (l cells)(-1) and half-saturation at 240 μM [Co(2+)](c). The tracer influx curves are adequately fitted by single exponentials, whereas the net influx curves all require at least double exponential fits, probably due to non-stationary A23187 kinetics. The rate of tracer influx decreases with increasing cobalt concentration, and increases with delayed addition of (57)Co tracer during net uptake. This might be explained by an 'auto-inhibition' by cobalt. The kinetics for A23187-mediated net and tracer influx of (54)Mn is very similar to that of (57)Co, whereas the net influx of (65)Zn can be fitted by single exponentials. In cobalt-loaded cells the cobalt is partly 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. However, all cell cobalt appears to exchange with (57)Co during tracer influx. It is speculated that oxidation of Co(2+) to Co(3+) could lead to the high affinity binding. Tight binding

  13. 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

  14. Photolysis and thermolysis of bis(imino)pyridine cobalt azides: C-H activation from putative cobalt nitrido complexes.

    Science.gov (United States)

    Hojilla Atienza, Crisita Carmen; Bowman, Amanda C; Lobkovsky, Emil; Chirik, Paul J

    2010-11-24

    A series of planar aryl-substituted bis(imino)pyridine cobalt azide complexes were prepared and evaluated as synthetic precursors for the corresponding cobalt nitrido compounds. Thermolysis or photolysis of two examples resulted in intramolecular C-H activation of the benzylic positions of the aryl substituents. For the mesityl-substituted compound, C-H activation by the putative nitride resulted in formation of a neutral imine ligand and modification of the chelate by hydrogen transfer to the imine carbon.

  15. Cobalt(I) Olefin Complexes: Precursors for Metal-Organic Chemical Vapor Deposition of High Purity Cobalt Metal Thin Films.

    Science.gov (United States)

    Hamilton, Jeff A; Pugh, Thomas; Johnson, Andrew L; Kingsley, Andrew J; Richards, Stephen P

    2016-07-18

    We report the synthesis and characterization of a family of organometallic cobalt(I) metal precursors based around cyclopentadienyl and diene ligands. The molecular structures of the complexes cyclopentadienyl-cobalt(I) diolefin complexes are described, as determined by single-crystal X-ray diffraction analysis. Thermogravimetric analysis and thermal stability studies of the complexes highlighted the isoprene, dimethyl butadiene, and cyclohexadiene derivatives [(C5H5)Co(η(4)-CH2CHC(Me)CH2)] (1), [(C5H5)Co(η(4)-CH2C(Me)C(Me)CH2)] (2), and [(C5H5)Co(η(4)-C6H8)] (4) as possible cobalt metal organic chemical vapor deposition (MOCVD) precursors. Atmospheric pressure MOCVD was employed using precursor 1, to synthesize thin films of metallic cobalt on silicon substrates under an atmosphere (760 torr) of hydrogen (H2). Analysis of the thin films deposited at substrate temperatures of 325, 350, 375, and 400 °C, respectively, by scanning electron microscopy and atomic force microscopy reveal temperature-dependent growth features. Films grown at these temperatures are continuous, pinhole-free, and can be seen to be composed of hexagonal particles clearly visible in the electron micrograph. Powder X-ray diffraction and X-ray photoelectron spectroscopy all show the films to be highly crystalline, high-purity metallic cobalt. Raman spectroscopy was unable to detect the presence of cobalt silicides at the substrate/thin film interface.

  16. Studies on the Displacement Reaction of Trialkylaluminum with Ethylene Catalyzed by Nitrogen Chelate Cobalt Complexes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The catalytic properties of a series of cobalt complexes containing bidenated nitrogen ligand for displacement reaction of trialkylaluminum with ethylene is reported. Effect of different reaction time, temperature and cobalt complexes containing different ligand on catalyst performance has been investigated.

  17. Cobalt-Blue Decoration Painted on Early Islamic White Glazed Wares

    OpenAIRE

    波頭, 桂

    1998-01-01

    White glazed ware with cobalt-blue decoration and white glazed ware with cobalt-blue and copper-green decoration, produced in Mesopotamia during the Abbasid period, are objects of this paper. Sherds of these types

  18. 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...

  19. Replacement of Cobalt base alloys hardfacing by NOREM alloy; EDF experience and development, some metallurgical considerations. Valves application (CLAMA, RAMA)

    Energy Technology Data Exchange (ETDEWEB)

    Carnus, M. [EDF DPN UTO Direction Expertise Technique, Noisy le Grand (France); Confort, X. [VELAN SAS, Lyon (France)

    2011-07-01

    Cobalt base alloys, such as Stellite 6 and 21, are used extensively in applications where superior resistance to wear and corrosion are required. However the use of Cobalt alloys hardfacing materials, especially on valves, is a major contributor to the level of radioactive contamination of nuclear facilities. NOREM alloys, an iron base and cobalt free materials, have been developed through an Electric Power Research Institute (EPRI) long running program during the eighties as an alternative of Stellite. This alloy has relatively good weldability properties, it was developed initially for repairing Stellite hardfacing (deposit over existing hardfacing alloys). This alloy has good corrosion resistance properties associated with elevated hardness (HRC 36-42). Technological properties (such as galling resistance, wear resistance) have been evaluated through different testing programs led by EPRI, AECL(Atomic Energy of Canada Limited), Valves manufacturers, EDF and others during the nineties. More recently EDF (for replacement of globe valves) has carried out testing program focused on weld deposit chemistry and mechanical properties. NOREM is a candidate for replacement of stellite hardfacing on valves. However this alloy is not so versatile as stellite alloys regarding technological properties (such as wear resistance) at elevated temperature and under high contact pressure. As a consequence some limits have to be considered for application on valves operating at elevated temperature and under high contact pressure (> 20 Mpa). Examples of application on valves, from VELAN manufacturer, for EDF PWR equipment are given. The industrial feedback from installed equipment (CLAMA, RAMA) since 2006 on EDF PWR has been good

  20. 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...

  1. Tailoring the oxidation state of cobalt through halide functionality in sol-gel silica

    OpenAIRE

    Gianni Olguin; Christelle Yacou; Simon Smart; 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 alt...

  2. Inhalation toxicity and carcinogenicity studies of cobalt sulfate.

    Science.gov (United States)

    Bucher, J R; Hailey, J R; Roycroft, J R; Haseman, J K; Sills, R C; Grumbein, S L; Mellick, P W; Chou, B J

    1999-05-01

    Cobalt sulfate is a water-soluble cobalt salt with a variety of industrial and agricultural uses. Several cobalt compounds have induced sarcomas at injection sites in animals, and reports have suggested that exposure to cobalt-containing materials may cause lung cancer in humans. The present studies were done because no adequate rodent carcinogenicity studies had been performed with a soluble cobalt salt using a route relevant to occupational exposures. Groups of 50 male and 50 female F344/N rats and B6C3F1 mice were exposed to aerosols containing 0, 0.3, 1.0, or 3.0 mg/m3 cobalt sulfate hexahydrate, 6 h/day, 5 days/week, for 104 weeks. Survival and body weights of exposed rats and mice were generally unaffected by the exposures. In rats, proteinosis, alveolar epithelial metaplasia, granulomatous alveolar inflammation, and interstitial fibrosis were observed in the lung in all exposed groups. Nonneoplastic lesions of the nose and larynx were also attributed to exposure to all concentrations of cobalt sulfate. In 3.0 mg/m3 male rats and in female rats exposed to 1.0 or 3.0 mg/m3, the incidences of alveolar/bronchiolar neoplasms were increased over those in the control groups. Lung tumors occurred with significant positive trends in both sexes. The incidences of adrenal pheochromocytoma in 1.0 mg/m3 male rats and in 3.0 mg/m3 female rats were increased. Nonneoplastic lesions of the respiratory tract were less severe in mice than in rats. In mice, alveolar/bronchiolar neoplasms in 3.0 mg/m3 males and females were greater than those in the controls, and lung tumors occurred with significantly positive trends. Male mice had liver lesions consistent with a Helicobacter hepaticus infection. Incidences of liver hemangiosarcomas were increased in exposed groups of male mice; however, because of the infection, no conclusion could be reached concerning an association between liver hemangiosarcomas and cobalt sulfate. In summary, exposure to cobalt sulfate by inhalation

  3. A new disubstituted polyacetylene bearing 6-benzylaminopurine moieties: postfunctional synthetic strategy and sensitive chemosensor towards copper and cobalt ions.

    Science.gov (United States)

    Ou, Daxin; Zhang, Liang; Huang, Yanfen; Lou, Xiaoding; Qin, Jingui; Li, Zhen

    2013-05-14

    A new 6-benzylaminopurine-functionalized disubstituted polyacetylene (P2) with strong green fluorescence is successfully synthesized by utilizing the postfunctional method. The polymer is soluble in common organic solvents, and its strong green fluorescence can be quenched by copper and cobalt ions with a detection limit down to 1.0 × 10(-8) (0.64 ppb) and 3.3 × 10(-8) mol L(-1) (1.94 ppb), respectively. Moreover, not much interference is observed from other metal ions, including Li(+) , Na(+) , K(+) , Fe(3+) , Fe(2+) , Ni(2+) , Hg(2+) , Mg(2+) , Al(3+) , Zn(2+) , Mn(2+) , Pb(2+) , Ba(2+) , Ca(2+) , Cd(2+) , Ag(+) , and Cr(3+) . Furthermore, P2 can be put into application using test strips, making P2 a practical, sensitive, and selective copper and cobalt probe.

  4. 揭密 Palm OS Cobalt

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    PalmSource公司于去年年底宣布向许可商提供Palm OS Cobalt,Palm OS Cobalt就是大家所谈论的Palm OS6操作系统。那么Palm OS6到底有什么新的特性?到底是何方神圣?能不能在争夺日益激烈的掌上设备操作系统中取得优势?在大家对Palm OS Cobalt盼望、猜测和充满疑问的时候,《数码·移动通讯》整理了一些读者们最感觉兴趣问题,通过越洋电话对Palm Source公司Palm OS Cobalt产品经理John Cook先生进行了独家专访,以下就是此次越洋电话专访的内容。

  5. Spinel cobalt ferrite by complexometric synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Thang, Pham D. [Inorganic Materials Science, Faculty of Science and Technology, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)]. E-mail: t.d.pham@tnw.utwente.nl; Rijnders, Guus [Inorganic Materials Science, Faculty of Science and Technology, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Blank, Dave H.A. [Inorganic Materials Science, Faculty of Science and Technology, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2005-09-15

    Magnetic fine particles of cobalt ferrite (CoFe{sub 2}O{sub 4}) have been synthesized using complexometric method in which ethylene diamine tetra acetic acid C{sub 10}H{sub 16}N{sub 2}O{sub 8} (EDTA) acts as a complexing agent. The crystallographic structure, microstructure and magnetic properties of the synthesized powder were characterized by using X-ray diffraction (XRD), particle size analysis and vibrating sample magnetometry (VSM). The material crystallized in cubic spinel structure with lattice parameter of about 8.38 A. Depending on the calcining temperature, the particle size of the powders varies in the range of hundreds of nanometers to tens of micrometers. A desired relative density above 95% of the theoretical value is obtained for the bulk sample after sintering. The calcined powders and sintered sample exhibit saturation magnetizations around 80 Am{sup 2}/kg which is expected for inverse CoFe{sub 2}O{sub 4}. With increasing calcining temperature the coercivity of these samples decreases. This simple synthesis route leads to a reproducible and stoichiometric material.

  6. Physiological Remediation of Cobalt Ferrite Nanoparticles by Ferritin

    Science.gov (United States)

    Volatron, Jeanne; Kolosnjaj-Tabi, Jelena; Javed, Yasir; Vuong, Quoc Lam; Gossuin, Yves; Neveu, Sophie; Luciani, Nathalie; Hémadi, Miryana; Carn, Florent; Alloyeau, Damien; Gazeau, Florence

    2017-01-01

    Metallic nanoparticles have been increasingly suggested as prospective therapeutic nanoplatforms, yet their long-term fate and cellular processing in the body is poorly understood. Here we examined the role of an endogenous iron storage protein - namely the ferritin - in the remediation of biodegradable cobalt ferrite magnetic nanoparticles. Structural and elemental analysis of ferritins close to exogenous nanoparticles within spleens and livers of mice injected in vivo with cobalt ferrite nanoparticles, suggests the intracellular transfer of degradation-derived cobalt and iron, entrapped within endogenous protein cages. In addition, the capacity of ferritin cages to accommodate and store the degradation products of cobalt ferrite nanoparticles was investigated in vitro in the acidic environment mimicking the physiological conditions that are present within the lysosomes. The magnetic, colloidal and structural follow-up of nanoparticles and proteins in the lysosome-like medium confirmed the efficient remediation of nanoparticle-released cobalt and iron ions by ferritins in solution. Metal transfer into ferritins could represent a quintessential process in which biomolecules and homeostasis regulate the local degradation of nanoparticles and recycle their by-products.

  7. Physiological Remediation of Cobalt Ferrite Nanoparticles by Ferritin.

    Science.gov (United States)

    Volatron, Jeanne; Kolosnjaj-Tabi, Jelena; Javed, Yasir; Vuong, Quoc Lam; Gossuin, Yves; Neveu, Sophie; Luciani, Nathalie; Hémadi, Miryana; Carn, Florent; Alloyeau, Damien; Gazeau, Florence

    2017-01-09

    Metallic nanoparticles have been increasingly suggested as prospective therapeutic nanoplatforms, yet their long-term fate and cellular processing in the body is poorly understood. Here we examined the role of an endogenous iron storage protein - namely the ferritin - in the remediation of biodegradable cobalt ferrite magnetic nanoparticles. Structural and elemental analysis of ferritins close to exogenous nanoparticles within spleens and livers of mice injected in vivo with cobalt ferrite nanoparticles, suggests the intracellular transfer of degradation-derived cobalt and iron, entrapped within endogenous protein cages. In addition, the capacity of ferritin cages to accommodate and store the degradation products of cobalt ferrite nanoparticles was investigated in vitro in the acidic environment mimicking the physiological conditions that are present within the lysosomes. The magnetic, colloidal and structural follow-up of nanoparticles and proteins in the lysosome-like medium confirmed the efficient remediation of nanoparticle-released cobalt and iron ions by ferritins in solution. Metal transfer into ferritins could represent a quintessential process in which biomolecules and homeostasis regulate the local degradation of nanoparticles and recycle their by-products.

  8. Cobalt(II) complexes with hydroxypyridines and halogenides

    Science.gov (United States)

    Dojer, Brina; Pevec, Andrej; Jagličić, Zvonko; Kristl, Matjaž

    2017-01-01

    We have synthesized and characterized two new cobalt(II) complexes: difluoridotetrakis(3-hydroxypyridine-κN)cobalt(II), [CoF2(C5H5NO)4] (1) and hexa(2-pyridone-κO)cobalt(II) tetrachloridocobaltate(II), [Co(C5H5NO)6][CoCl4] (2). The complexes were prepared by solvothermal synthesis. A methanol solution of hydroxypyridine was added to water solution of cobalt(II) acetate dihydrate followed by a few drops of concentrated hydrofluoric or hydrochloric acid into the mixture. The crystals of the compounds 1 and 2 are stable on air. The compounds were characterized structurally by single-crystal X-ray diffraction analysis, spectrally by FT-IR spectroscopy and thermally. Thermal analysis showed that the final product of both complexes after heating to 900 °C is elemental cobalt. The interactions between building units in the crystal structures include intra- and intermolecular hydrogen bonds in both compounds and π-π interactions in compound 2.

  9. Enhancement of trichothecene production in Fusarium graminearum by cobalt chloride.

    Science.gov (United States)

    Tsuyuki, Rie; Yoshinari, Tomoya; Sakamoto, Naoko; Nagasawa, Hiromichi; Sakuda, Shohei

    2011-03-09

    The effects of cobalt chloride on the production of trichothecene and ergosterol in Fusarium graminearum were examined. Incorporation experiments with (13)C-labeled acetate and leucine confirmed that both 3-acetyldeoxynivalenol and ergosterol were biosynthesized via a mevalonate pathway by the fungus, although hydroxymethyl-glutaryl CoA (HMG-CoA) from intact leucine was able to be partially used for ergosterol production. Addition of cobalt chloride at concentrations of 3-30 μM into liquid culture strongly enhanced 3-acetyldeoxynivalenol production by the fungus, whereas the amount of ergosterol and the mycelial weight of the fungus did not change. The mRNA levels of genes encoding trichothecene biosynthetic proteins (TRI4 and TRI6), ergosterol biosynthetic enzymes (ERG3 and ERG25), and enzymes involved in the mevalonate pathway (HMG-CoA synthase (HMGS) and HMG-CoA reductase (HMGR)) were all strongly up-regulated in the presence of cobalt chloride. Precocene II, a specific trichothecene production inhibitor, suppressed the effects of cobalt chloride on Tri4, Tri6, HMGS, and HMGR, but did not affect erg3 and erg25. These results indicate that cobalt chloride is useful for investigating regulatory mechanisms of trichothecene and ergosterol production in F. graminearum.

  10. 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

  11. Graphene/cobalt nanocarrier for hyperthermia therapy and MRI diagnosis.

    Science.gov (United States)

    Hatamie, Shadie; Ahadian, Mohammad Mahdi; Ghiass, Mohammad Adel; Iraji Zad, Azam; Saber, Reza; Parseh, Benyamin; Oghabian, Mohammad Ali; Shanehsazzadeh, Saeed

    2016-10-01

    Graphene/cobalt nanocomposites are promising materials for theranostic nanomedicine applications, which are defined as the ability to diagnose, provide targeted therapy and monitor the response to the therapy. In this study, the composites were synthesized via chemical method, using graphene oxide as the source material and assembling cobalt nanoparticles of 15nm over the surface of graphene sheets. Various characterization techniques were then employed to reveal the morphology, size and structure of the nanocomposites, such as X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy and ultraviolet visible spectroscopy. Using ion-coupled plasma optical emission spectroscopy, cobalt concentration in the nanocomposites was found to be 80%. In addition, cytotoxicity of graphene/cobalt nanocomposites were evaluated using 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide or MTT assay. MTT viability assay exhibited biocompatibility to L929 mouse fibroblasts cells, under a high dose of 100μg/mL over 24h. Hyperthermia results showed the superior conversion of electromagnetic energy into heat at 350kHz frequency for 0.01 and 0.005g/L of the nanocomposites solution. The measured heat generation and energy transfer results were anticipated by the finite element analysis, conducted for the 3D structure. Magnetic resonance imaging characteristics also showed that negatively charge graphene/cobalt nanocomposites are suitable for T1-weighted imaging. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Preparation of Ultrafine Cobalt Powder by Chemical Reduction in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline cobalt powders have been prepared from aqueous solution by reducing their corresponding metal salts under suitable conditions. The experimental conditions have been studied in detail. X-ray powder diffraction patterns show that the cobalt powder is hexagonal crystallite. The average particle size of the ultrafine cobalt powder is 55 nm.

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 75 FR 70665 - Proposed Significant New Use Rule for Cobalt Lithium Manganese Nickel Oxide

    Science.gov (United States)

    2010-11-18

    ... AGENCY 40 CFR Part 721 RIN 2070-AB27 Proposed Significant New Use Rule for Cobalt Lithium Manganese...) for the chemical substance identified as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1... substance identified as cobalt lithium manganese nickel oxide (PMN P-04-269; CAS No. 182442-95-1). This...

  1. 76 FR 47996 - Cobalt Lithium Manganese Nickel Oxide; Significant New Use Rule

    Science.gov (United States)

    2011-08-08

    ... AGENCY 40 CFR Parts 9 and 721 RIN 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Significant New Use... chemical substance identified as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1), which was the... 5(a)(2) (15 U.S.C. 2604(a)(2)) for the chemical substance identified as cobalt lithium...

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

    Science.gov (United States)

    2010-11-18

    ... AGENCY 40 CFR Parts 9 and 721 RIN 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Withdrawal of... Control Act (TSCA) for the chemical substance identified as cobalt lithium manganese nickel oxide (CAS No... cobalt lithium manganese nickel oxide (PMN P-04-269; CAS No. 182442-95-1) at 40 CFR 721.10201 because...

  3. Synthesis and characterization of α-cobalt hydroxide nanobelts

    Science.gov (United States)

    Tian, L.; Zhu, J. L.; Chen, L.; An, B.; Liu, Q. Q.; Huang, K. L.

    2011-08-01

    α-Cobalt hydroxide was synthesized by a facile hydrothermal process from Co(Ac)2 and NH3·H2O in the presence of 1,3-propanediol. The large-scale-prepared cobalt hydroxide has a uniform nanobelt morphology with a considerably high aspect-ratio more than 20 which may be advantageous for exploration of their physicochemical properties. This synthetic method is convenient, economical, and controllable. The samples were characterized by powder X-ray diffraction, energy dispersive spectrum, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, CHN element analysis, thermogravimetric and differential-thermogravimetric analysis, which revealed the compound is lamellar structural cobalt organic-inorganic hybrid with the chemical formula of Co(OH)1.49(NH3)0.01(CO3 2-)0.22(Ac-)0.07(H2O)0.11 and single-crystalline.

  4. Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.

    Science.gov (United States)

    Sanpo, Noppakun; Berndt, Christopher C; Wen, Cuie; Wang, James

    2013-03-01

    Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles.

  5. Cobalt toxicity after McKee hip arthroplasty.

    Science.gov (United States)

    Jones, D A; Lucas, H K; O'Driscoll, M; Price, C H; Wibberley, B

    1975-08-01

    The significance of cobalt as a cause of symptoms after McKee hip arthroplasty is discussed. Seven patients are described in whom such arthroplasties. became unsatisfactory after periods varying from nine months to four years. Six of these patients were cobalt-positive but nickel- and chrome-negative on patch testing. Macroscopic and histological necrosis of bone, muscle and joint capsule around the prostheses was found in five patients whose hips were explored. The symptoms were progressive pain, a feeling of instability, and in two cases spontaneous dislocation. Radiological features included acetabular fracture, bone resorption, loosening and dislocation of the prosthesis. Increased cobalt concentrations (determined by atomic absorption spectrophotometry) in the urine of four patients and in a variety of tissues in one patient are presented. Patch testing is recommended in the investigation of patients with troublesome McKee hip arthroplasties

  6. Magnetic properties of cobalt microwires measured by piezoresistive cantilever magnetometry

    Directory of Open Access Journals (Sweden)

    Tosolini G.

    2014-09-01

    Full Text Available We present the magnetic characterization of cobalt wires grown by focused electron beam-induced deposition (FEBID and studied using static piezoresistive cantilever magnetometry. We have used previously developed high force sensitive submicron-thick silicon piezoresistive cantilevers. High quality polycrystalline cobalt microwires have been grown by FEBID onto the free end of the cantilevers using dual beam equipment. In the presence of an external magnetic field, the magnetic cobalt wires become magnetized, which leads to the magnetic field dependent static deflection of the cantilevers. We show that the piezoresistive signal from the cantilevers, corresponding to a maximum force of about 1 nN, can be measured as a function of the applied magnetic field with a good signal to noise ratio at room temperature. The results highlight the flexibility of the FEBID technique for the growth of magnetic structures on specific substrates, in this case piezoresistive cantilevers.

  7. Hepatic cobalt and copper levels in lambs in Norway.

    Science.gov (United States)

    Sivertsen, T; Plassen, C

    2004-01-01

    Cobalt and copper concentrations were measured in 599 lamb livers collected at slaughter from 58 sheep flocks in 6 different parts of Norway in 1993. Information about pasture, additional feeding and mineral supplements in the flocks was obtained through a questionnaire. Average hepatic levels of cobalt in the lamb flocks varied from copper from 5 to 240 microg/g ww. Flocks with deficient or marginal cobalt status were found in all parts of southern Norway, but primarily in the west and south-west. Some flocks with marginal copper status were found in the south-west, while flocks with signs of excessive hepatic copper concentrations were found mainly in inner parts of central and northern Norway. Hepatic copper concentrations were significantly higher in lambs that had grazed mountain pastures than in those that had grazed lowland pastures in the summer.

  8. Anisotropic Magnetoresistance of Cobalt Films Prepared by Thermal Evaporation

    Directory of Open Access Journals (Sweden)

    Yuttanun PANSONG

    2005-01-01

    Full Text Available Cobalt films on silicon substrates were prepared by thermal evaporation. By evaporating 0.05 g of cobalt for 80-240 s, a thickness from 21.1 to 67.7 nm was obtained with a deposition rate about 0.26-0.32 nm per second. The 29 nm-thick cobalt film exhibited magnetoresistance (MR ranging from -0.0793% (field perpendicular to the current to +0.0134% (field parallel to the current with saturation in a 220 mT magnetic field. This MR was attributed to anisotropic magnetoresistance (AMR since changing the angle between the field and the current (θ gave rise to a change in the electrical resistance (Rθ. The results agreed with the theory since the plot between Rθ and cos2θ could be linearly fitted. AMR was not observed in non-ferromagnetic gold films whose resistance was insensitive to the angle between the current and magnetic field.

  9. Electrodeposition of Compositionally Modulated Zinc-cobalt Alloy Multilayer Coatings

    Institute of Scientific and Technical Information of China (English)

    费敬银; 梁国正; 辛文利

    2005-01-01

    The effects of pulse parameters on the cobalt content, surface morphologies and grain size of Zn-Co alloy deposits were studied using a pulse plating technique with a square-wave current containing reverse pulse. Average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. Grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current. Varieties of Zn-Co alloy compositionally modulated multilayer (CMM) coatings with large differences in cobalt contents for different sublayers were electrodeposited by designing corresponding waveforms using a computer-aided pulse plater and characterized in terms of surface morphologies. Cross-sectional morphologies of the Zn-Co alloy CMM coatings, examined using field emission gun scanning electron microscopy (FEGSEM), confirmed the layered structure.

  10. Effect of Cobalt Particle Size on Acetone Steam Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junming; Zhang, He; Yu, Ning; Davidson, Stephen; Wang, Yong

    2015-06-11

    Carbon-supported cobalt nanoparticles with different particle sizes were synthesized and characterized by complementary characterization techniques such as X-ray diffraction, N-2 sorption, acetone temperature-programmed desorption, transmission electron microscopy, and CO chemisorption. Using acetone steam reforming reaction as a probe reaction, we revealed a volcano-shape curve of the intrinsic activity (turnover frequency of acetone) and the CO2 selectivity as a function of the cobalt particle size with the highest activity and selectivity observed at a particle size of approximately 12.8nm. Our results indicate that the overall performance of acetone steam reforming is related to a combination of particle-size-dependent acetone decomposition, water dissociation, and the oxidation state of the cobalt nanoparticles.

  11. Tungsten-nickel-cobalt alloy and method of producing same

    Science.gov (United States)

    Dickinson, James M.; Riley, Robert E.

    1977-03-15

    An improved tungsten alloy having a tungsten content of approximately 95 weight percent, a nickel content of about 3 weight percent, and the balance being cobalt of about 2 weight percent is described. A method for producing said tungsten-nickel-cobalt alloy is further described and comprises (a) coating the tungsten particles with a nickel-cobalt alloy, (b) pressing the coated particles into a compact shape, (c) heating said compact in hydrogen to a temperature in the range of 1400.degree. C and holding at this elevated temperature for a period of about 2 hours, (d) increasing this elevated temperature to about 1500.degree. C and holding for 1 hour at this temperature, (e) cooling to about 1200.degree. C and replacing the hydrogen atmosphere with an inert argon atmosphere while maintaining this elevated temperature for a period of about 1/2 hour, and (f) cooling the resulting alloy to room temperature in this argon atmosphere.

  12. Practical and clinical considerations in Cobalt-60 tomotherapy

    Directory of Open Access Journals (Sweden)

    Joshi Chandra

    2009-01-01

    Full Text Available Cobalt-60 (Co-60 based radiation therapy continues to play a significant role in not only developing countries, where access to radiation therapy is extremely limited, but also in industrialized countries. Howver, technology has to be developed to accommodate modern techniques, in-clud-ing image guided and adaptive radiation therapy (IGART. In this paper we describe some of the practical and clinical considerations for Co-60 based tomotherapy by comparing Co-60 and 6 MV linac-based tomotherapy plans for a head and neck (HandN cancer and a prostate cancer case. The tomotherapy IMRT plans were obtained by modeling a MIMiC binary multi-leaf collimator attached to a Theratron-780c Co-60 unit and a 6 MV linear accelerator (CL2100EX. The EGSnrc/BEAMnrc Monte Carlo (MC code was used for the modeling of the treatment units with the MIMiC collimator and EGSnrc/DOSXYZnrc code was used for beamlet dose data. An in-house inverse treatment planning program was then used to generate optimized tomotherapy dose distributions for the H and N and prostate cases. The dose distributions, cumulative dose area histograms (DAHs and dose difference maps were used to evaluate and compare Co-60 and 6 MV based tomotherapy plans. A quantitative analysis of the dose distributions and dose-volume histograms shows that both Co-60 and 6 MV plans achieve the plan objectives for the targets (CTV and nodes and OARs (spinal cord in HandN case, and rectum in prostate case.

  13. 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

  14. Impact of nickel and cobalt on biogas production and process stability during semi-continuous anaerobic fermentation of a model substrate for maize silage.

    Science.gov (United States)

    Pobeheim, Herbert; Munk, Bernhard; Lindorfer, Harald; Guebitz, Georg M

    2011-01-01

    The importance of nickel and cobalt on anaerobic degradation of a defined model substrate for maize was demonstrated. Five semi-continuous reactors were operated for 250 days at 35 °C and a well-defined trace metal solution was added to all reactors. Two reactors each were limited regarding the concentration of Ni(2+) and Co(2+), respectively, for certain time intervals. The required nickel concentration was depending on the organic loading rates (OLR) while, for example, above 2.6 g ODM L(-1) d(-1) nickel concentrations below 0.06 mg kg(-1) FM in the process significantly decreased biogas production by up to 25% compared to a control reactor containing 0.8 mg Ni(2+) kg(-1) FM. Similarly, limitation of cobalt to 0.02 mg kg(-1) FM decreased biogas production by about 10%. Limitations of nickel as well as cobalt lead to process instability. However, after gradual addition of nickel till 0.6 mg and cobalt till 0.05 mg kg(-1) FM the OLR was again increased to 4.3 g ODM L(-1) d(-1) while process stability was recovered and a fast metabolisation of acetic and propionic acid was detected. An increase of nickel to 0.88 mg kg(-1) FM did not enhance biogas performance. Furthermore, the increase of cobalt from 0.05 mg kg(-1) FM up to 0.07 mg kg(-1) FM did not exhibit a change in anaerobic fermentation and biogas production.

  15. Polymer templated nickel cobaltate for energy storage★

    Directory of Open Access Journals (Sweden)

    Albohani Shaymaa

    2017-01-01

    Full Text Available In order to take advantage of the increasing sophistication of technology for harnessing renewable energy resources, serious attention must be paid to how to store and re-access this energy. Electrochemical storage, in the guise of batteries, supercapacitors and pseudocapacitors, has attracted much attention as a viable option for enhanced energy storage applications. But in order for these technologies to be implemented successfully we need to find materials that perform better and are relatively easy to synthesise. Bimetallic transition metal oxides are materials that are readily synthesised and may be multifunctional, i.e. have a role at the electrochemical atomic level as well as the device level. In order for these materials to work efficiently in new generation systems based on sodium and lithium they also need to be mesoporous. This can be achieved by trying to find synthetic techniques that produce specific, highly regulated nanostructures or by adding a ‘templating’ agent during the bulk synthesis step. We have investigated the simple hydrothermal preparation of a number of nickel cobaltate (NiCo2O4 materials using polymer templates, eggshell membrane (ESM and poly methyl methacrylate (PMMA, as potential electrode materials for supercapacitors. The ESM was expected to act as a fibrous, random polymeric template while the PMMA should produce a much more ordered material. Electrochemical testing showed that the different templates have led to changes in material morphology and these have resulted in a difference in electrochemical properties. Templated materials increased specific capacitance compared to non-templated and the choice of template could influence the capacitance by as much as 30%.

  16. Nanofibre growth from cobalt carbide produced by mechanosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Barriga-Arceo, L [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas 152, Colonia San Bartolo Atepehuacan, Mexico DF, 07730 (Mexico); Orozco, E [Instituto de Fisica UNAM, Apartado Postal 20-364 CP 01000, DF (Mexico); Garibay-Febles, V [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas 152, Colonia San Bartolo Atepehuacan, Mexico DF, 07730 (Mexico); Bucio-Galindo, L [Instituto de Fisica UNAM, Apartado Postal 20-364 CP 01000, DF (Mexico); Mendoza Leon, H [FM-UPALM, IPN, Apartado Postal 75-395 CP 07300, DF (Mexico); Castillo-Ocampo, P [UAM-Iztapalapa, Apartado Postal 55-334 CP 09340, DF (Mexico); Montoya, A [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas 152, Colonia San Bartolo Atepehuacan, Mexico DF, 07730 (Mexico)

    2004-06-09

    Mechanical alloying was used to prepare cobalt carbide. Microstructural characterization of samples was performed by x-ray diffraction, differential scanning calorimetry and transmission electron microscopy methods. In order to produce carbon nanotubes, the cobalt carbide was precipitated after heating at 800 and 1000 deg. C for 10 min. Nanofibres of about 10-50 nm in diameter, 0.04-0.1 {mu}m in length and 20-200 nm in diameter and 0.6-1.2 {mu}m in length were obtained after heating at 800 and 1000 deg. C, respectively, by means of this process.

  17. Cobalt Ferrite Nanocrystallites for Sustainable Hydrogen Production Application

    Directory of Open Access Journals (Sweden)

    Rajendra S. Gaikwad

    2011-01-01

    Full Text Available Cobalt ferrite, CoFe2O4, nanocrystalline films were deposited using electrostatic spray method and explored in sustainable hydrogen production application. Reflection planes in X-ray diffraction pattern confirm CoFe2O4 phase. The surface scanning microscopy photoimages reveal an agglomeration of closely-packed CoFe2O4 nanoflakes. Concentrated solar-panel, a two-step water splitting process, measurement technique was preferred for measuring the hydrogen generation rate. For about 5 hr sustainable, 440 mL/hr, hydrogen production activity was achieved, confirming the efficient use of cobalt ferrite nanocrystallites film in hydrogen production application.

  18. 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

  19. Excessive erythrocytosis, chronic mountain sickness, and serum cobalt levels.

    Science.gov (United States)

    Jefferson, J Ashley; Escudero, Elizabeth; Hurtado, Maria-Elena; Pando, Jacqueline; Tapia, Rosario; Swenson, Erik R; Prchal, Josef; Schreiner, George F; Schoene, Robert B; Hurtado, Abdias; Johnson, Richard J

    2002-02-01

    In a subset of high-altitude dwellers, the appropriate erythrocytotic response becomes excessive and can result in chronic mountain sickness. We studied men with (study group) and without excessive erythrocytosis (packed-cell volume >65%) living in Cerro de Pasco, Peru (altitude 4300 m), and compared them with controls living in Lima, Peru (at sea-level). Toxic serum cobalt concentrations were detected in 11 of 21 (52%) study participants with excessive erythrocytosis, but were undetectable in high altitude or sea-level controls. In the mining community of Cerro de Pasco, cobalt toxicity might be an important contributor to excessive erythrocytosis.

  20. PLUTONIUM-CERIUM-COBALT AND PLUTONIUM-CERIUM-NICKEL ALLOYS

    Science.gov (United States)

    Coffinberry, A.S.

    1959-08-25

    >New plutonium-base teroary alloys useful as liquid reactor fuels are described. The alloys consist of 10 to 20 atomic percent cobalt with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 88 atomic percent; or, of from 10 to 25 atomic percent nickel (or mixture of nickel and cobalt) with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 86 atomic percent. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are a lower melting point and a wide range of permissible plutonium dilution.

  1. From nanotechnology to nanogenotoxicology: genotoxic effect of cobalt-chromium nanoparticles

    Directory of Open Access Journals (Sweden)

    Zülal Atlı Şekeroğlu

    2013-03-01

    Full Text Available Nanotechnology is a multi-disciplinary technology that processes the materials that can be measured with nanometer-level and combines many research field or discipline. Nanomaterials (NMs are widely used in the fields of science, technology, communication, electronics, industry, pharmacy, medicine, environment, consumer products and military. Until recently little has been known about whether or not nanomaterials have the toxic or hazardous effects on human health and the environment. However, several studies have indicated that exposure to some nanomaterials, e.g. nanoparticles, can cause some adverse effects in humans and animals. Over the last years the number of publications focusing on nanotoxicology has gained momentum, but, there is still a gap about the genotoxicity of nanomaterials.Metal nanoparticles and their alloys with excellent mechanical properties are the materials which can be easily adapted to the mechanical conditions of the musculoskeletal system. Cobalt-chromium alloys are widely used in orthopedic applications as joint prosthesis and bone regeneration material, fillings and dental implants in jaw surgery, and in cardiovascular surgery, especially stent applications. Studies about cytotoxicity and genotoxicity of metal nanoparticles on human indicate that some metal nanoparticles have cytotoxic and genotoxic effects and they may be hazardous for humans. However, a few studies have been reported concerning the genotoxic effects of cobalt-chromium nanoparticles. The data from these studies indicate that cobalt-chromium nanoparticles have cytotoxic and genotoxic effects. It has been stated that the wear debris from implants cause DNA and chromosome damage in patients with cobalt-chromium replacements. It was also found that the risk of urinary cancers such as bladder, ureter, kidney and prostate in patients after hip replacement than among the wider population.Because there are very little biocompatibility and toxicity tests on

  2. In situ cobalt-cobalt oxide/N-doped carbon hybrids as superior bifunctional electrocatalysts for hydrogen and oxygen evolution.

    Science.gov (United States)

    Jin, Haiyan; Wang, Jing; Su, Diefeng; Wei, Zhongzhe; Pang, Zhenfeng; Wang, Yong

    2015-02-25

    Remarkable hydrogen evolution reaction (HER) or superior oxygen evolution reaction (OER) catalyst has been applied in water splitting, however, utilizing a bifunctional catalyst for simultaneously generating H2 and O2 is still a challenging issue, which is crucial for improving the overall efficiency of water electrolysis. Herein, inspired by the superiority of carbon conductivity, the propitious H atom binding energy of metallic cobalt, and better OER activity of cobalt oxide, we synthesized cobalt-cobalt oxide/N-doped carbon hybrids (CoOx@CN) composed of Co(0), CoO, Co3O4 applied to HER and OER by simple one-pot thermal treatment method. CoOx@CN exhibited a small onset potential of 85 mV, low charge-transfer resistance (41 Ω), and considerable stability for HER. Electrocatalytic experiments further indicated the better performance of CoOx@CN for HER can be attributed to the high conductivity of carbon, the synergistic effect of metallic cobalt and cobalt oxide, the stability of carbon-encapsulated Co nanoparticles, and the introduction of electron-rich nitrogen. In addition, when used as catalysts of OER, the CoOx@CN hybrids required 0.26 V overpotential for a current density of 10 mA cm(-2), which is comparable even superior to many other non-noble metal catalysts. More importantly, an alkaline electrolyzer that approached ∼20 mA cm(-2) at a voltage of 1.55 V was fabricated by applying CoOx@CN as cathode and anode electrocatalyst, which opened new possibilities for exploring overall water splitting catalysts.

  3. The effect of microstructure on the wear of cobalt-based alloys used in metal-on-metal hip implants.

    Science.gov (United States)

    Varano, R; Bobyn, J D; Medley, J B; Yue, S

    2006-02-01

    The influence of microstructure on the wear of cobalt-based alloys used in metal-on-metal hip implants was investigated in a boundary lubrication regime designed to represent the conditions that occurred some of the time in vivo. These cobalt-chromium-molybdenum alloys were either wrought, with a total carbon content of 0.05 or 0.23 wt %, cast with a solution-annealing procedure or simply as-cast but not solution annealed. Bars of these different alloy grades were subjected to various heat treatments to develop different microstructures. The wear was evaluated in a linear-tracking reciprocating pin-on-plate apparatus with a 25 per cent bovine serum lubricant. The wear was found to be strongly affected by the dissolved carbon content of the alloys and mostly independent of grain size or the carbide characteristics. The increased carbon in solid solution caused reductions in volumetric wear because carbon helped to stabilize a face-centred cubic crystal structure, thus limiting the amount of strain-induced transformation to a hexagonal close-packed crystal structure. Based on the observed surface twining in and around the contact zone and the potentially detrimental effect of the hexagonal close-packed phase, it was postulated that the wear of cobalt-based alloys in the present study was controlled by a deformation mechanism.

  4. Effect of sample preparation methods on photometric determination of the tellurium and cobalt content in the samples of copper concentrates

    Directory of Open Access Journals (Sweden)

    Viktoriya Butenko

    2016-03-01

    Full Text Available Methods of determination of cobalt and nickel in copper concentrates currently used in factory laboratories are very labor intensive and time consuming. The limiting stage of the analysis is preliminary chemical sample preparation. Carrying out the decomposition process of industrial samples with concentrated mineral acids in open systems does not allow to improve the metrological characteristics of the methods, for this reason improvement the methods of sample preparation is quite relevant and has a practical interest. The work was dedicated to the determination of the optimal conditions of preliminary chemical preparation of copper concentrate samples for the subsequent determination of cobalt and tellurium in the obtained solution using tellurium-spectrophotometric method. Decomposition of the samples was carried out by acid dissolving in individual mineral acids and their mixtures by heating in an open system as well as by using ultrasonification and microwave radiation in a closed system. In order to select the optimal conditions for the decomposition of the samples in a closed system the phase contact time and ultrasonic generator’s power were varied. Intensification of the processes of decomposition of copper concentrates with nitric acid (1:1, ultrasound and microwave radiation allowed to transfer quantitatively cobalt and tellurium into solution spending 20 and 30 min respectively. This reduced the amount of reactants used and improved the accuracy of determination by running the process in strictly identical conditions.

  5. Development of hierarchically porous cobalt oxide for enhanced photo-oxidation of indoor pollutants

    Science.gov (United States)

    Cheng, J. P.; Shereef, Anas; Gray, Kimberly A.; Wu, Jinsong

    2015-03-01

    Porous cobalt oxide was successfully prepared by precipitation of cobalt hydroxide followed by low temperature thermal decomposition. The morphologies of the resultant oxides remained as the corresponding hydroxides, although the morphology of cobalt hydroxides was greatly influenced by the precursor salts. The cobalt oxides with average crystal size less than 20 nm were characterized by X-ray diffraction, scanning electron microscope, BET surface area, and XPS analysis. The photocatalytic activities of the various cobalt oxides morphologies were investigated by comparing the photo-degradation of acetaldehyde under simulated solar illumination. Relative to their low order structures and reference titania samples, the hierarchical nanostructures of cobalt oxide showed excellent abilities to rapidly degrade acetaldehyde, a model air pollutant. This was attributed to the unique nature of these hierarchical cobalt oxide nanoassemblies, which contained many catalytically active reaction sites and open pores.

  6. Development of hierarchically porous cobalt oxide for enhanced photo-oxidation of indoor pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, J. P., E-mail: chengjp@zju.edu.cn [Zhejiang University, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering (China); Shereef, Anas; Gray, Kimberly A., E-mail: k-gray@northwestern.edu [Northwestern University, Center for Catalysis and Surface Science (United States); Wu, Jinsong [Northwestern University, Department of Materials Science and Engineering (United States)

    2015-03-15

    Porous cobalt oxide was successfully prepared by precipitation of cobalt hydroxide followed by low temperature thermal decomposition. The morphologies of the resultant oxides remained as the corresponding hydroxides, although the morphology of cobalt hydroxides was greatly influenced by the precursor salts. The cobalt oxides with average crystal size less than 20 nm were characterized by X-ray diffraction, scanning electron microscope, BET surface area, and XPS analysis. The photocatalytic activities of the various cobalt oxides morphologies were investigated by comparing the photo-degradation of acetaldehyde under simulated solar illumination. Relative to their low order structures and reference titania samples, the hierarchical nanostructures of cobalt oxide showed excellent abilities to rapidly degrade acetaldehyde, a model air pollutant. This was attributed to the unique nature of these hierarchical cobalt oxide nanoassemblies, which contained many catalytically active reaction sites and open pores.

  7. Electrochemically fabricated polypyrrole-cobalt-oxygen coordination complex as high-performance lithium-storage materials.

    Science.gov (United States)

    Guo, Bingkun; Kong, Qingyu; Zhu, Ying; Mao, Ya; Wang, Zhaoxiang; Wan, Meixiang; Chen, Liquan

    2011-12-23

    Current lithium-ion battery (LIB) technologies are all based on inorganic electrode materials, though organic materials have been used as electrodes for years. Disadvantages such as limited thermal stability and low specific capacity hinder their applications. On the other hand, the transition metal oxides that provide high lithium-storage capacity by way of electrochemical conversion reaction suffer from poor cycling stability. Here we report a novel high-performance, organic, lithium-storage material, a polypyrrole-cobalt-oxygen (PPy-Co-O) coordination complex, with high lithium-storage capacity and excellent cycling stability. Extended X-ray absorption fine structure and Raman spectroscopy and other physical and electrochemical characterizations demonstrate that this coordination complex can be electrochemically fabricated by cycling PPy-coated Co(3)O(4) between 0.0 V and 3.0 V versus Li(+)/Li. Density functional theory (DFT) calculations indicate that each cobalt atom coordinates with two nitrogen atoms within the PPy-Co coordination layer and the layers are connected with oxygen atoms between them. Coordination weakens the C-H bonds on PPy and makes the complex a novel lithium-storage material with high capacity and high cycling stability.

  8. Cobalt oxide acicular nanorods with high sensitivity for the non-enzymatic detection of glucose.

    Science.gov (United States)

    Kung, Chung-Wei; Lin, Chia-Yu; Lai, Yi-Hsuan; Vittal, R; Ho, Kuo-Chuan

    2011-09-15

    Acicular cobalt oxide nanorods (CoONRs) were prepared for the non-enzymatic detection of glucose, first by directly growing layered cobalt carbonate hydroxide (LCCH) on a conducting fluorine-doped tin oxide (FTO) substrate using a simple chemical bath deposition (CBD) technique and then by transforming the LCCH into CoONRs through pyrolysis. The composition and grain size of the films of LCCH and CoONRs were verified by X-ray diffraction (XRD); their morphologies were examined by scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images. CoONRs showed high electrocatalytic activity for the electro-oxidation of glucose in alkaline media, and the activity was strongly influenced by NaOH concentration, annealing temperature of CoONRs, and thickness of CoONRs film. The pertinent sensor could be successfully used for the quantification of glucose by amperometric method. The sensing parameters include wide linear range up to 3.5 mM, a high sensitivity of 571.8 μA/(cm(2) mM), and a remarkable low detection limit of 0.058 μM. The CoONRs modified electrode exhibited a high selectivity for glucose in human serum, against ascorbic acid, uric acid, and acetaminophen.

  9. Enhanced electrochemical sensing of thiols based on cobalt phthalocyanine immobilized on nitrogen-doped graphene.

    Science.gov (United States)

    Xu, Huiying; Xiao, Jingjing; Liu, Baohong; Griveau, Sophie; Bedioui, Fethi

    2015-04-15

    A hybrid nanocomposite based on cobalt phthalocyanine (CoPc) immobilized on nitrogen-doped graphene (N-G) (N-G/CoPc) has been developed to modify glassy carbon electrode (GCE) for the sensitive detection of thiols. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Cyclic voltammetric studies showed that cobalt phthalocyanine and nitrogen doped graphene have a synergic effect and significantly enhance the electrocatalytic activity of the modified electrode towards thiols oxidation compared with electrodes modified with solely CoPc or N-G. The electrochemical oxidation responses were studied and the reaction mechanisms were discussed. The sensors exhibited a wide linear response range from 1μΜ to 16mM and a low detection limit of 1μΜ for the determination of l-cysteine, reduced l-glutathione and 2-mercaptoethanesulfonic acid in alkaline aqueous solution. The proposed N-G/CoPc hybrids contribute to the construction of rapid, convenient and low-cost electrochemical sensors for sensitive detection of thiols. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Survey of cosmetics for arsenic, cadmium, chromium, cobalt, lead, mercury, and nickel content.

    Science.gov (United States)

    Hepp, Nancy M; Mindak, William R; Gasper, John W; Thompson, Christopher B; Barrows, Julie N

    2014-01-01

    As part of efforts to assess amounts of inorganic element contamination in cosmetics, the U.S. Food and Drug Administration contracted a private laboratory to determine the total content of seven potentially toxic or allergenic elements in 150 cosmetic products of 12 types (eye shadows, blushes, lipsticks, three types of lotions, mascaras, foundations, body powders, compact powders, shaving creams, and face paints). Samples were analyzed for arsenic, cadmium, chromium, cobalt, lead, and nickel by inductively coupled plasma-mass spectrometry and for mercury by cold vapor atomic fluorescence spectrometry. The methods used to determine the elements were tested for validity by using standard reference materials with matrices similar to the cosmetic types. The cosmetic products were found to contain median values of 0.21 mg/kg arsenic, 3.1 mg/kg chromium, 0.91 mg/kg cobalt, 0.85 mg/kg lead, and 2.7 mg/kg nickel. The median values for cadmium and mercury were below the limits of detection of the methods. The contract requirements, testing procedures, and findings from the survey are described.

  11. Cobalt doping of the MOF-5 framework and its effect on gas-adsorption properties.

    Science.gov (United States)

    Botas, Juan A; Calleja, Guillermo; Sánchez-Sánchez, Manuel; Orcajo, M Gisela

    2010-04-20

    Partial isomorphic substitution of Zn in IRMOF metal clusters by cobalt ions is described for the first time. Specifically, different numbers of Co(2+) ions have been incorporated during solvothermal crystallization into the Zn-based MOF-5 (IRMOF-1) framework, which is one of the most studied MOF materials. The amount of Zn that can be substituted seems to be limited, being no more than 25% of total metal content, that is, no more than one Co atom inside every metal cluster formed by four transition-metal ions, on average. Several characterization techniques, including X-ray diffraction, DR UV-visible spectroscopy, N(2) adsorption isotherms, and thermogravimetrical analysis, strongly support the effective incorporation of Co into the material framework. As-synthesized CoMOF-5 has cobalt ions in octahedral coordination, changing to tetrahedral by simple evacuation, presumably by the removal of two diethylformamide molecules per Co ion. Moreover, the H(2), CH(4), and CO(2) uptake of MOF-5 materials systematically increases with the Co content, particularly at high pressure. Such an increase is moderate anyway, considering that Co is incorporated into unexposed metal sites that are less accessible to gas molecules.

  12. Photocatalytic H2 production from water with rhenium and cobalt complexes.

    Science.gov (United States)

    Probst, Benjamin; Guttentag, Miguel; Rodenberg, Alexander; Hamm, Peter; Alberto, Roger

    2011-04-18

    Photocatalytic hydrogen production in pure water for three component systems using a series of rhenium-based photosensitizers (PS) and cobalt-based water reduction catalysts (WRC), with triethanolamine (TEOA) as an irreversible electron donor, is described. Besides the feasibility of this reaction in water, key findings are reductive quenching of the excited state of the PS by TEOA (k(q) = 5-8 × 10(7) M(-1) s(-1); Φ(cage) = 0.75) and subsequent transfer of an electron to the WRC (k(Co(III)) = 1.1 × 10(9) M(-1) s(-1)). Turnover numbers in rhenium (TON(Re), H/Re) above 500 were obtained, whereas TON(Co) (H(2)/Co) did not exceed 17. It is shown that the cobalt-based WRC limits long-term performance. Long-term performance critically depends on pH and the type of WRC used but is unaffected by the type of PS or the concentration of WRC. A quantum yield of 30% was obtained (H/photon).

  13. Solution-based synthesis of cobalt-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vempati, Sesha [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Shetty, Amitha [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); Dawson, P., E-mail: p.dawson@qub.ac.uk [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Nanda, K.K.; Krupanidhi, S.B. [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-01

    Undoped and cobalt-doped (1-4 wt.%) ZnO polycrystalline, thin films have been fabricated on quartz substrates using sequential spin-casting and annealing of simple salt solutions. X-ray diffraction (XRD) reveals a wurzite ZnO crystalline structure with high-resolution transmission electron microscopy showing lattice planes of separation 0.26 nm, characteristic of (002) planes. The Co appears to be tetrahedrally co-ordinated in the lattice on the Zn sites (XRD) and has a charge of + 2 in a high-spin electronic state (X-ray photoelectron spectroscopy). Co-doping does not alter the wurzite structure and there is no evidence of the precipitation of cobalt oxide phases within the limits of detection of Raman and XRD analysis. Lattice defects and chemisorbed oxygen are probed using photoluminescence and Raman spectroscopy - crucially, however, this transparent semiconductor material retains a bandgap in the ultraviolet (3.30-3.48 eV) and high transparency (throughout the visible spectral regime) across the doping range. - Highlights: Black-Right-Pointing-Pointer Simple solution-based method for the fabrication of Co-doped ZnO thin films. Black-Right-Pointing-Pointer Evidence for Co substitution on Zn sites in + 2 oxidation state. Black-Right-Pointing-Pointer ZnO, with up to 4% Co doping, retains high transparency across visible spectrum. Black-Right-Pointing-Pointer Quenching of exciton photoluminescence linked to chemisorbed oxygen in Co-doped ZnO.

  14. Electrocatalytic amperometric determination of amitrole using a cobalt-phthalocyanine-modified carbon paste electrode.

    Science.gov (United States)

    Chicharro, Manuel; Zapardiel, Antonio; Bermejo, Esperanza; Moreno, Mónica; Madrid, Elena

    2002-07-01

    Cobalt-phthalocyanine-modified carbon paste electrodes are shown to be excellent indicators for electrocatalytic amperometric measurements of triazolic herbicides such as amitrole, at low oxidation potentials (+0.40 V). The detection and determination of amitrole in flow injection analysis with a modified carbon paste electrode with Co-phthalocyanine is described. The concentrations of amitrole in 0.1 M NaOH solutions were determined using the electrocatalytic oxidation signal corresponding to the Co(II)/Co(III) redox process. A detection limit of 0.04 microg mL(-1) (4 ng amitrole) was obtained for a sample loop of 100 microL at a fixed potential of +0.55 V (vs. Ag/AgCl) in 0.1 M NaOH and a flow rate of 4.0 mL min(-1). Furthermore, the modified carbon paste electrodes offers reproducible responses in such a system, and the relative standard deviation was 3.3% using the same surface, 5.1% using different surface, and 6.9% using different pastes. The performance of the cobalt-phthalocyanine-modified carbon paste electrodes is illustrated here for the determination of amitrole in commercial formulations. The response of the electrodes is stable, with more than 80% of the initial retained activity after 50 min of continuous use.

  15. Influence of cobalt and manganese content on the dehydrogenation capacity and kinetics of air-exposed LaNi{sub 5+x}-type alloys in solid gas and electrochemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Raekelboom, E.; Cuevas, F.; Percheron-Guegan, A. [Laboratoire de Chimie Metallurgique des Terres Rares CNRS, 2-8 rue Henri Dunant, 94320 Thiais (France); Knosp, B. [SAFT, 111 bd. Alfred Daney, 33074 Bordeaux (France)

    2007-07-10

    The effect of cobalt and manganese content on the dehydrogenation properties of air-exposed MmB{sub 5+x}-type (Mm = mischmetal; B = Ni, Al, Co and Mn) alloys was investigated both in solid gas and electrochemical reactions. The cobalt and manganese content were varied separately while keeping constant the plateau pressure of the hydrides. The increase of the cobalt content leads to a decrease of the hydrogen capacity whereas the manganese content has no much effect. In solid gas reactions, the kinetics were found to be limited by the hydrogen diffusion through the surface oxidation layer. As for the electrochemistry, the kinetics are limited by a corrosion layer formed in alkaline medium. The desorption rates for both processes increase as the cobalt or manganese content decreases. This is thought to be due to an enhancement of the hydrogen diffusivity through the oxidation layer. As a result, a low cobalt or manganese content in MmB{sub 5+x} alloys is found to be beneficial for the hydrogen desorption kinetics in both processes. (author)

  16. 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

    1997-01-01

    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

  17. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    Energy Technology Data Exchange (ETDEWEB)

    Andreici, Emiliana-Laura, E-mail: andreicilaura@yahoo.com [Department of Physics, West University of Timisoara, Bd. V. Parvan 4,300223 Timisoara (Romania); Petkova, Petya [Shumen University “Konstantin Preslavsky”, 115 Universitetska street, 9712 Shumen (Bulgaria); Avram, Nicolae M. [Department of Physics, West University of Timisoara, Bd. V. Parvan 4,300223 Timisoara (Romania); Academy of Romanian Scientists, Independentei 54, 050094-Bucharest (Romania)

    2015-12-07

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  18. 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

  19. 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...

  20. Study of DNA interaction with cobalt ferrite nanoparticles.

    Science.gov (United States)

    Pershina, A G; Sazonov, A E; Novikov, D V; Knyazev, A S; Izaak, T I; Itin, V I; Naiden, E P; Magaeva, A A; Terechova, O G

    2011-03-01

    Interaction of cobalt ferrite nanopowder and nucleic acid was investigated. Superparamagnetic cobalt ferrite nanoparticles (6-12 nm) were prepared by mechanochemical synthesis. Structure of the nanopowder was characterized using X-ray diffraction. It was shown that cobalt ferrite nanoparticles were associated with ssDNA and dsDNA in Tris-buffer resulting in bionanocomposite formation with mass weight relation nanoparticles: DNA 1:(0.083 +/- 0.003) and 1:(0.075 +/- 0.003) respectively. The mechanism of interaction between a DNA and cobalt ferrite nanoparticles was considered basing on the whole set of obtained data: FTIR-spectroscopy, analyzing desorption of DNA from the surface of the particles while changing the chemical content of the medium, and on the modeling interaction of specific biomolecule fragments with surface of a inorganic material. It was supposed that the linkage was based on coordination interaction of the phosphate groups and oxygen atoms heterocyclic bases of DNA with metal ions on the particle surface. These data can be used to design specific magnetic DNA-nanoparticles hybrid structures.

  1. Cobalt uptake and binding in human red blood cells

    DEFF Research Database (Denmark)

    Simonsen, Lars Ole; Brown, Anthony M; Harbak, Henrik

    2011-01-01

    The basal uptake and cytoplasmic binding of cobalt was studied in human red cells using (57)Co as tracer. The basal uptake is linear with time, at a rate of about 10 µmol (l cells)(-1) h(-1) at 100 µM [Co(2+)](o), and is almost irreversible, as there is hardly any efflux into excess EDTA. Ionophore...

  2. 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 achie

  3. Cobalt Cardiomyopathy Secondary to Hip Arthroplasty: An Increasingly Prevalent Problem

    Directory of Open Access Journals (Sweden)

    Russel Tilney

    2017-01-01

    Full Text Available A forty-year-old man experienced worsening heart failure four years following bilateral complicated total hip replacement. His condition was extensively worked up but no underlying pathology was immediately evident. Given the cobalt-chromium alloy component present in the hip arthroplasties, the raised cobalt blood levels, and a fitting clinical picture coupled with radiological findings, the patient underwent right hip revision. Evidence of biotribocorrosion was present on direct visualisation intraoperatively. The patient subsequently experienced symptomatic improvement (NYHA class III to class I and echocardiography showed recovery of ejection fraction. Cobalt exists as a bivalent and trivalent molecule in circulation and produces a cytotoxicity profile similar to nanoparticles, causing neurological, thyroid, and cardiological pathology. Blood levels are not entirely useful as there is no identifiable conversion factor for levels in whole blood, serum, and erythrocytes which seem to act independently of each other. Interestingly cobalt cardiomyopathy is frequently compounded by other possible causes of cardiomyopathy such as alcohol and a link has been postulated. Definitive treatment is revision of the arthroplasty as other treatments are unproven.

  4. 46 SPIDER WEBS AS INDICATORS OF COBALT AND LEAD ...

    African Journals Online (AJOL)

    Department of Chemistry, Sa'adatu Rimi College of Education, Kumbotso. PMB 3218 Kano- ... The analysis of the webs showed different levels of the metals in the indoor and ... the microbial flora, provided a sufficient amount of cobalt is ...

  5. 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.

  6. 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.

  7. Geometrical product specifications heat-resistant cobalt cast alloy

    Directory of Open Access Journals (Sweden)

    Lyubimov V.

    2007-01-01

    Full Text Available Geometrical product specification MAR-M509 cast cobalt alloy depend beginning temperature of multilayer ceramic shell moulds (MCS. It has found that go down temperature of MCS from 1000°C to 200°C, the increase surface roughness and its amplitude parameters: Sa, Sz, St, Sq, Sp and Sv.

  8. Cobalt chromium stents versus stainless steel stents in diabetic patients

    Directory of Open Access Journals (Sweden)

    Mahmoud Ahmed Tantawy

    2014-03-01

    Conclusions: We concluded that no significant statistical difference was found between the two stents (cobalt-chromium alloy bare metal stent versus conventional bare metal stainless steel stent in diabetic patients regarding (initial procedural success, in-hospital complications, the incidence of ISR at follow up, event-free survival at follow up.

  9. Dissolution of atmospheric cobalt and zinc in seawater

    Directory of Open Access Journals (Sweden)

    C.-E. Thuróczy

    2009-11-01

    Full Text Available Atmospheric dust inputs to the open ocean are major source of trace metals bioavailable for the phytoplankton after their dissolution in seawater. Among them, cobalt (Co and zinc (Zn are essential for the growth and for the distribution of major phytoplankton taxon such as coccolithophorids and diatoms. The solubility in seawater of Co and Zn present in atmospheric dusts was studied using an open-flow reactor with and without light irradiation. The analyses of cobalt and Zinc were conducted using voltammetric methods and the global elemental composition of dust determined by ICP-AES. This study highlights the role of the dust origin in revealing the solubility characteristics. Higher dust solubility was found for zinc as compared to cobalt. Cobalt in anthropogenic particles is much more soluble in seawater than in natural particles after 2 h of dissolution. Zinc showed opposite solubilities, higher in natural particles than in anthropogenics. This work is a contribution to ongoing studies which focus on the impact of atmospheric inputs of trace metals onto the primary production.

  10. 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...

  11. 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.

  12. Combined use of HPLC-ICP-MS and microwave-assisted extraction for the determination of cobalt compounds in nutritive supplements.

    Science.gov (United States)

    Yang, Fang-Yu; Jiang, Shiuh-Jen; Sahayam, A C

    2014-03-15

    Speciation analysis of cobalt in nutritive supplements has been carried out using HPLC and ICP-MS equipped with a membrane desolvation sample introduction system as detector. In this study, cobalt containing compounds, namely Co(II), cyanocobalamin (CN-Cbl) and hydroxylcobalamin (OH-Cbl), were well separated by reversed phase HPLC with a C8-HPLC column as the stationary phase and 8 mmol L(-1) ammonium acetate in 22%v/v methanol solution (pH 4) as the mobile phase using isocratic elution. Detection limit was in the range of 0.008-0.014 μg CoL(-1) for various Co species. Over 98% of the total cobalt species was extracted in nutritive supplements using a 0.5%v/v HNO3 solution in a microwave field; and the spike recovery was in the range of 92-108% for various species. The HPLC-ICP-MS results showed a satisfactory agreement with the total cobalt concentrations obtained by ICP-MS analysis of completely dissolved samples.

  13. Atomically Precise Growth of Catalytically Active Cobalt Sulfide on Flat Surfaces and within a Metal-Organic Framework via Atomic Layer Deposition.

    Science.gov (United States)

    Peters, Aaron W; Li, Zhanyong; Farha, Omar K; Hupp, Joseph T

    2015-08-25

    Atomic layer deposition (ALD) has been employed as a new synthetic route to thin films of cobalt sulfide on silicon and fluorine-doped tin oxide platforms. The self-limiting nature of the stepwise synthesis is established through growth rate studies at different pulse times and temperatures. Additionally, characterization of the materials by X-ray diffraction and X-ray photoelectron spectroscopy indicates that the crystalline phase of these films has the composition Co9S8. The nodes of the metal-organic framework (MOF) NU-1000 were then selectively functionalized with cobalt sulfide via ALD in MOFs (AIM). Spectroscopic techniques confirm uniform deposition of cobalt sulfide throughout the crystallites, with no loss in crystallinity or porosity. The resulting material, CoS-AIM, is catalytically active for selective hydrogenation of m-nitrophenol to m-aminophenol, and outperforms the analogous oxide AIM material (CoO-AIM) as well as an amorphous CoSx reference material. These results reveal AIM to be an effective method of incorporating high surface area and catalytically active cobalt sulfide in metal-organic frameworks.

  14. A novel separation/preconcentration procedure using in situ sorbent formation microextraction for the determination of cobalt (II in water and food samples by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Jamali

    2017-05-01

    Full Text Available A new, simple, low cost, and rapid solid phase extraction method, that was named in situ sorbent formation microextraction (ISSFME, was developed for the selective separation and determination of cobalt (II in various water and food samples. In the present work, cetyltrimethylammonium bromide was used as a cationic surfactant, perchlorate ion as an ion-pairing agent, and 2-nitroso-1-naphthol as a complexing agent. After extraction, the concentration of cobalt was determined by flame atomic absorption spectrometer. Several variables that affect the extraction efficiencies were investigated and optimized. Under the optimized conditions, the limit of detection was 0.8 μg L−1 with a preconcentration factor of 50. The RSD for 10 replicate measurements of 50 μg L−1 of cobalt was 2.3%. The accuracy and applicability of the method were tested by evaluating the amount of cobalt in water certified reference materials and various water and food samples.

  15. Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints.

    Science.gov (United States)

    Zupancic, Rok; Legat, Andraz; Funduk, Nenad

    2006-10-01

    The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. The average tensile strength of brazed joints was 792 MPa and was significantly greater (P<.05) than the tensile strength of both types of

  16. 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.

  17. Effect of rare earth substitution in cobalt ferrite bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Bulai, G., E-mail: georgiana.bulai@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania); Diamandescu, L. [National Institute of Material Physics, P.O. Box MG-7, 07125 Bucharest (Romania); Dumitru, I.; Gurlui, S. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania); Feder, M. [National Institute of Material Physics, P.O. Box MG-7, 07125 Bucharest (Romania); Caltun, O.F. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania)

    2015-09-15

    The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm{sup −3} decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe{sub 2}O{sub 4} sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples. - Highlights: • Substitution by a large number of rare earth elements was investigated. • First reported results on magnetostriction measurements of RE doped cobalt ferrite. • The doped samples presented an increased porosity and a decreased grain size. • Increased magnetostrctive response was observed for several doped samples.

  18. Porous nickel MCFC cathode coated by potentiostatically deposited cobalt oxide

    Energy Technology Data Exchange (ETDEWEB)

    Escudero, M.J.; Gonzalez, T.; Daza, L. [Dpto. Energia, CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Mendoza, L.; Cassir, M. [Instituto de Catalisis y Petroleoquimica (CSIC), Campus Cantoblanco, 28049 Madrid (Spain)

    2006-10-06

    Cobalt oxide was deposited on porous nickel by an electrodeposition technique as precursor of a novel MCFC cathode. The behavior of this cathode in molten (Li{sub 0.52}Na{sub 0.48}){sub 2}CO{sub 3} eutectics at 650{sup o}C under an atmosphere of CO{sub 2}:air (30:70) was studied before and after 50h of exposure by different techniques. Before the exposure, the deposit of cobalt corresponded to a Co{sub 3}O{sub 4} thin layer of. This crystalline structure was identified by XRD and Raman spectroscopy. After its exposure in the eutectic melt a loss of cobalt was observed by XRD, Raman spectroscopy, XPS, EDS and ICP-AES. The change in the Co{sub 3}O{sub 4} structure into lithium-cobalt-nickel oxide (LiCo{sub 1-y}Ni{sub y}O{sub 2}) was observed by Raman spectroscopy. The SEM micrographs for Co{sub 3}O{sub 4}-coated porous nickel showed different angular shapes with respect to porous Ni. The nickel solubility for the coated porous nickel, measured by ICP-AES, decreased with respect to uncoated nickel. The Co{sub 3}O{sub 4}-coated porous nickel cathode showed, after its immersion in the molten carbonate melt, a similar porosity but a higher pore size. LiCo{sub 1-y}Ni{sub y}O{sub 2}-coated NiO offers interesting features which combine the properties of nickel, lithium and cobalt in molten carbonate. This could be a promising novel MCFC cathode material. (author)

  19. Interdependence between urinary cobalt concentrations and hemoglobin levels in pregnant women.

    Science.gov (United States)

    Fort, Marta; Grimalt, Joan O; Casas, Maribel; Sunyer, Jordi

    2015-01-01

    Cobalt is an essential trace element but may cause toxic effects upon occupational or environmental exposure. Women accumulate more cobalt than men at similar exposure levels which may be related to higher metabolic iron loss. During pregnancy these losses are much stronger but their influence on cobalt intake has not been studied. We have studied the associations between changes in hemoglobin and cobalt urinary excretion during pregnancy. 391 pairs of urine and blood samples from pregnant women were collected during the 12th and 32nd weeks of pregnancy and were analyzed for cobalt and hemoglobin. Mean concentrations of urinary cobalt were 0.73 and 1.6 µg/g creatinine during the first and third trimesters, respectively (pcobalt in the third than in the first trimester. Cobalt concentrations were negatively associated to hemoglobin levels in the third trimester (pcobalt increases between these two periods. This correspondence involved a statistically significant difference in third trimester mean cobalt concentrations of anemic and non-anemic women, 1.8 and 1.5 µg/g creatinine, respectively (pcobalt urine levels found in pregnant women may be related to higher intestinal absorption of cobalt at iron depletion such as in the last pregnancy period when iron body demands are high. Possible toxicity effects of these cobalt increases along pregnancy should be considered in cases of populations occupationally or environmentally exposed to this metal.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sandre, C.; Moulin, C.; Bresson, C. [CEA Saclay, DEN, SECR, Lab Speciat Radionucleides and Mol, F-91191 Gif Sur Yvette (France); Gault, N. [CEA Fontenay Roses, DSV IRCM SCSR LRTS, F-92265 Fontenay Aux Roses (France); Poncy, J. L. [CEA Bruyeres Le Chatel, DSV IRCM SREIT LRT, F-91680 Bruyeres Le Chatel (France); Lefaix, J. L. [CEA Caen, DSV IRCM SRO LARIA, F-14070 Caen (France)

    2010-07-01

    Cobalt (Co) is an essential trace element well known as a constituent of vitamin B{sub 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, {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)

  1. 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)

  2. Synthesis and Characterization of Cobalt-Carbon Core-Shell Microspheres in Supercritical Carbon Dioxide System

    Institute of Scientific and Technical Information of China (English)

    Jun-song Yang; Qian-wang Chen

    2008-01-01

    The synthesis of cobalt-carbon core-shell microspheres in supercritical carbon dioxide system was investigated. Cobalt-carbon core-shell microspheres with diameter of about 1μm were prepared at 350℃ for 12 h in a closed vessel containing an appropriate amount of bis(cyclopentadienyl)cobalt powder and dry ice.Characterization by a variety of techniques,including X-ray powder diffraction,X-ray photoelectron spectroscopy,Transmission electron microscope,Fourier transform infrared spectrum and Raman spectroscopy analysis reveals that each cobalt-carbon core-shell microsphere is made up of an amorphous cobalt core with diameter less than 1 μm and an amorphous carbon shell with thickness of about 200 nm.The possible growth mechanism of cobalt-carbon core-shell microspheres is discussed,based on the pyrolysis of bis(cyclopentadienyl)cobalt in supercritical carbon dioxide and the deposition of carbon or carbon clusters with odd electrons on the surface of magnetic cobalt cores due to magnetic attraction.Magnetic measurements show 141.41 emu/g of saturation magnetization of a typical sample,which is lower than the 168 emu/g of the corresponding metal cobalt bulk material.This is attributed to the considerable mass of the carbon shell and amorphous nature of the magnetic core.Control of magnetism in the cobalt-carbon core-shell microspheres was achieved by annealing treatments.

  3. How NO affects nickel and cobalt nitrates at low temperatures to arrive at highly dispersed silica-supported nickel and cobalt catalysts

    NARCIS (Netherlands)

    Wolters, M.; Munnik, P.; Bitter, J.H.; de Jongh, P.E.; de Jong, K.P.

    2011-01-01

    Impregnation of porous silica supports with cobalt and nickel nitrate precursor solutions is a convenient method to prepare supported nickel and cobalt (oxide) catalysts. However, the metal (oxide) dispersion obtained is highly dependent on the gas atmosphere during thermal treatment to convert the

  4. Magneto-structural correlations in rare-earth cobalt pnictides

    Science.gov (United States)

    Thompson, Corey Mitchell

    Magnetic materials are used in many applications such as credit cards, hard drives, electric motors, sensors, etc. Although a vast range of magnetic solids is available for these purposes, our ability to improve their efficiency and discover new materials remains paramount to the sustainable progress and economic profitability in many technological areas. The search for magnetic solids with improved performance requires fundamental understanding of correlations between the structural, electronic, and magnetic properties of existing materials, as well as active exploratory synthesis that targets the development of new magnets. Some of the strongest permanent magnets, Nd 2Fe14B, SmCo5, and Sm2Co17, combine transition and rare-earth metals, benefiting from the strong exchange between the 4f and 3d magnetic sublattices. Although these materials have been studied in great detail, the development of novel magnets requires thorough investigation of other 3d-4 f intermetallics, in order to gain further insights into correlations between their crystal structures and magnetic properties. Among many types of intermetallic materials, ternary pnictides RCo 2Pn2 (R = La, Ce, Pr, Nd; Pn = P, As) are of interest because, despite their simple crystal structures, they contain two magnetic sublattices, exchange interactions between which may lead to rich and unprecedented magnetic behavior. Nevertheless, magnetism of these materials was studied only to a limited extent, especially as compared to the extensive studies of their silicide and germanide analogues. The ThCr2Si2 structure type, to which these ternary pnictides belong, is one of the most ubiquitous atomic arrangements encountered among intermetallic compounds. It accounts for over 1000 known intermetallics and has received increased attention due to the recently discovered FeAs-based superconductors. This dissertation is devoted to the investigation of magnetostructural relationships and anomalous magnetic behaviors in rare

  5. Cobalt(II)-selective membrane electrode based on a recently synthesized benzo-substituted macrocyclic diamide.

    Science.gov (United States)

    Shamsipur, M; Poursaberi, T; Rouhani, S; Niknam, K; Sharghi, H; Ganjali, M R

    2001-09-01

    A PVC-membrane electrode based on a recently synthesized 18-membered macrocyclic diamide is presented. The electrode reveals a Nernstian potentiometric response for Co2+ over a wide concentration range (2.0 x 10(-6)-1.0 x 10(-2) M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities for Co2+ over a wide variety of other metal ions, and could be used over a wide pH range (3.0-8.0). The detection limit of the sensor is 6.0 x 10(-7) M. It was successfully applied to the direct determination and potentiometric titration of cobalt ion.

  6. Enhancing Surface Finish of Additively Manufactured Titanium and Cobalt Chrome Elements Using Laser Based Finishing

    Science.gov (United States)

    Gora, Wojciech S.; Tian, Yingtao; Cabo, Aldara Pan; Ardron, Marcus; Maier, Robert R. J.; Prangnell, Philip; Weston, Nicholas J.; Hand, Duncan P.

    Additive manufacturing (AM) offers the possibility of creating a complex free form object as a single element, which is not possible using traditional mechanical machining. Unfortunately the typically rough surface finish of additively manufactured parts is unsuitable for many applications. As a result AM parts must be post-processed; typically mechanically machined and/or and polished using either chemical or mechanical techniques (both of which have their limitations). Laser based polishing is based on remelting of a very thin surface layer and it offers potential as a highly repeatable, higher speed process capable of selective area polishing, and without any waste problems (no abrasives or liquids). In this paper an in-depth investigation of CW laser polishing of titanium and cobalt chrome AM elements is presented. The impact of different scanning strategies, laser parameters and initial surface condition on the achieved surface finish is evaluated.

  7. The 23 to 300 C demagnetization resistance of samarium-cobalt permanent magnets

    Science.gov (United States)

    Niedra, Janis M.; Overton, Eric

    1991-01-01

    The influence of temperature on knee point and squareness of the M-H demagnetization characteristic of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperature in demagnetization resistent permanent magnet devices. Composite plots of the knee field and the demagnetizing field required to produce a given magnetic induction swing below remanence were obtained for several commercial Sm2Co17 type magnet samples in the temperature range of 23 to 300 C. Using the knee point to define the limits of operation safe against irreversible demagnetization, such plots are shown to provide an effective overview of the useable regions in the space of temperature-induction swing parameters. The observed second quadrant M-H characteristic squareness is shown, by two measures, to increase gradually with temperature, reaching a peak in the interval 200 to 300 C.

  8. Cloud point extraction, preconcentration and simultaneous spectrophotometric determination of nickel and cobalt in water samples

    Science.gov (United States)

    Safavi, A.; Abdollahi, H.; Hormozi Nezhad, M. R.; Kamali, R.

    2004-10-01

    Cloud point extraction has been used for the preconcentration and simultaneous spectrophotometric determination of nickel and cobalt after the formation of a complex with 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA), and latter analysis by spectrophotometer using Triton X-114 as surfactant. The parameters affecting the separation phase and detection process were optimized. Under the optimum experimental conditions (i.e. pH=5, 0.07 mM ACDA, Triton X-114 = 0.25% (w/v)), calibration graphs were linear in the range of 20-500 and 20-200 μg l -1 with detection limits of 10 and 7.5 μg l -1 for Ni and Co, respectively. The method was applied to the determination of Ni and Co in natural and waste water samples with satisfactory results.

  9. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  10. Size effects in thermoelectric cobaltate heterostructures

    NARCIS (Netherlands)

    Brinks, Petrus

    2014-01-01

    Thermoelectric energy conversion is a promising method to convert (waste) heat into useful electrical energy. To improve the efficiency of this process, which is currently limited, materials with improved thermoelectric performance are required. The performance indicator for thermoelectric materials

  11. Cobalt (II)-EDTA complex as a new reductant for phosphomolybdic acid used for the assay of trazodone

    Indian Academy of Sciences (India)

    A V S S Prasad; C S P Sastry

    2003-02-01

    A new spectrophotometric method for the assay of trazodone (TZ) has been described. TZ forms a complex in stoichiometric proportions with phosphomolybdic acid. The released phosphomolybdic acid from the complex with acetone is reduced with a new reductant (cobalt nitrate-ethylenediamine tetra acetic acid) to molybdenum blue, which has maximum absorption at 840 nm. Beer's law limits, precision and accuracy of the methods are checked by the UV reference method. This method is found to be suitable for the assay of TZ in the presence of other ingredients that are usually present in tablets. Recoveries are almost quantitative.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lison, D. (Industrial Toxicology and Occupational Medicine Unit, Catholic Univ. of Louvain, Brussels (Belgium)); Lauwerys, R. (Industrial Toxicology and Occupational Medicine Unit, Catholic Univ. of Louvain, Brussels (Belgium))

    1994-08-01

    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. (orig.)

  13. 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.

  14. 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.

  15. 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.

  16. Immobilization of cobalt in collapsed non-irradiated and {gamma}-irradiated X zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Enrique [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D.F. (Mexico) and Universidad Autonoma Metropolitana, Iztapalapa, Av. San Rafael Atlixco No. 186 Col. Vicentina, 09340 Mexico D.F. (Mexico)]. E-mail: lima@xanum.uam.mx; Bosch, Pedro [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Bulbulian, Silvia [Instituto Nacional de Investigaciones Nucleares, Col. Escandon, Delegacion Miguel Hidalgo, 11801 Mexico D.F. (Mexico)

    2007-02-15

    Cobalt exchanged X zeolites were gamma irradiated and heated until the zeolite structure collapsed. Heating destroys the zeolite network as found by X-ray-diffraction and {sup 29}Si, {sup 27}Al MAS NMR spectroscopy. Gamma irradiation treatment diminished the collapsing temperature of zeolite. Cobalt leaching from crystalline and amorphized zeolites was verified by ion exchange with NaCl solution. Results show that cobalt is not released from the amorphous materials. Furthermore adsorption of xenon and {sup 129}Xe NMR spectroscopy reveal that cobalt ions are heterogeneously distributed in the non irradiated amorphous materials. Gamma irradiation causes the mobility of cobalt in the amorphous materials resulting then in a more homogeneous distribution. Cobalt is, thus, retained safely in the amorphous materials.

  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 avoidance...... [1]. In 2014, we performed a questionnaire study, which showed a positive and significant association between cobalt allergy and a history of dermatitis caused by non-occupational exposure to leather articles [2]. Recently, we published an article showing high amounts of cobalt in selected leather...... 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. 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

  19. 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...... of gold contact are only understood on a rudimentary level, which at present prevents further exploration. We have synthesized a model system of flat, layered cobalt oxide nanoislands supported on a single crystal gold (111) substrate....

  20. Effects of Cobalt on the Sintering Behavior of Mechanically Activated Tungsten Powder

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Tungsten alloys were prepared with mechanically activated powder added microelement cobalt in order to improve the process and properties of alloys. Properties of alloys such as density, hardness and bending strength were measured. The results show that through mechanical activation, cobalt can accelerate the sintering process of these alloys. By the combination of mechanical activation and adding microelement cobalt, tungsten alloys with higher density and better properties can be obtained.

  1. Moessbauer and magnetic studies of cobalt substituted lithium zinc ferrites prepared by citrate precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Soibam, Ibetombi [Department of Physics, Manipur University, Canchipur, Imphal 795003, Manipur (India)], E-mail: ibetombi_phys@rediffmail.com; Phanjoubam, Sumitra [Department of Physics, Manipur University, Canchipur, Imphal 795003, Manipur (India); Prakash, Chandra [Directorate of ER and IPR, DRDO Bhawan, Rajaji Marg, New Delhi 110011 (India)

    2009-05-05

    Nanocrystalline lithium zinc ferrites substituted with cobalt were synthesized by the citrate precursor method. X-ray diffraction was used to confirm the spinel phase. Moessbauer studies at room temperature were carried out to study the effect of cobalt concentration on the various hyperfine interactions. Variation of the saturation magnetization with respect to composition was discussed. The result shows some anomalous behaviour when cobalt is substituted to lithium ferrite in presence of zinc.

  2. Calorimetric examination of mixtures for modification of nickel and cobalt superalloys

    OpenAIRE

    F. Binczyk; J. Sleziona; R. Przeliorz

    2009-01-01

    The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at hightemperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations andmeasurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flourZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possib...

  3. Exposure to Cobalt Causes Transcriptomic and Proteomic Changes in Two Rat Liver Derived Cell Lines

    Science.gov (United States)

    2013-12-30

    Cobalt can enter the body through respiration, ingestion, or contact with the skin . The adverse effects of an inhalation exposure occur mostly in the lung...exposures are unlikely to have systemic effects as cobalt cannot readily penetrate normal skin , although contact with cobalt can cause dermatitis [16...heavy chain 4 Mug1/Mug2 murinoglobulin 1/2 NAMPT nicotinamide phosphoribosyltransferase Pzp pregnancy zone protein SERPINA1 serine (or cysteine

  4. The Revovery of Copper and Cobalt from Oxidized Copper Ore and Converter Slag

    OpenAIRE

    ZİYADANOĞULLARI, Berrin; ZİYADANOĞULLARI, Recep

    1999-01-01

    The aim of this study was to develop a method for obtaining copper and cobalt from oxidized copper ore and converter slag. In order to convert the copper and cobalt into sulfate compounds the main step was to roast the samples obtained by sulfurization and transfer the samples into solution. First the oxidized copper ore was roasted, followed by the mixture of converter slag and oxidized copper ore. Since the levels of copper and cobalt were low, the sulfurization process was carri...

  5. Optic Neuropathy from Cobalt Toxicity in a Patient who Ingested Cattle Magnets

    OpenAIRE

    Bhardwaj, Namita; Perez, Javier; Peden, Marc

    2011-01-01

    Cobalt is a widely used in the industrial production of hard metals. Cobalt ingestion has been reported to cause widespread systemic toxicity, but its effects on vision have been sparsely reported. The authors report the case of a patient who ingested cattle magnets, which remained in his stomach for an unknown duration of time. These magnets largely consist of cobalt that gradually leached into his blood stream, resulting in protean systemic manifestations, which included optic atrophy.

  6. 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...

  7. Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative

    Science.gov (United States)

    2014-11-01

    1 ASETSDefense 2014 Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative Ruben A. Prado, CEF...COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative...Mil-Spec development 3 ASETSDefense 2014 ■ Demonstrate/Validate pulsed electrodeposition of Nanocrystalline Cobalt -Phosphorous (nCoP) alloy

  8. Structural and magnetic study of dysprosium substituted cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hemaunt, E-mail: hvatsal@gmail.com [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Srivastava, R.C. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Pal Singh, Jitendra [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Negi, P. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Agrawal, H.M. [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Das, D. [UGC-DAE CSR Kolkata Centre, Kolkata 700098 (India); Hwa Chae, Keun [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of)

    2016-03-01

    The present work investigates the magnetic behavior of Dy{sup 3+} substituted cobalt ferrite nanoparticles. X-ray diffraction studies reveal presence of cubic spinel phases in these nanoparticles. Raman spectra of these nanoparticles show change in intensity of Raman bands, which reflects cation redistribution in cubic spinel lattice. Saturation magnetization and coercivity decrease with increase of Dy{sup 3+}concentration in these nanoparticles. Room temperature Mössbauer measurements show the cation redistribution in these nanoparticles and corroborates the results obtained from Raman Spectroscopic measurements. Decrease in magnetization of Dy{sup 3+} substituted cobalt ferrite is attributed to the reduction in the magnetic interaction and cation redistribution. - Highlights: • Slight decrease in crystallite size after Dy{sup 3+} doping. • Saturation magnetization and coercivity decrease after Dy{sup 3+} doping. • Mössbauer measurements show the cation redistribution in the samples.

  9. 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).

  10. Recovery of copper and cobalt by biopolymer gels.

    Science.gov (United States)

    Jang, L K; Lopez, S L; Eastman, S L; Pryfogle, P

    1991-02-05

    The recovery of copper from synthetic aqueous media circulating in a loop fluidized bed reactor operated batchwise was investigated by using the following biopolymer systems: (1) a viscous solution of sodium alginate (from kelp) dispensed directly into the reactor fluid containing dissolved copper (sulfate salt) at initial concentrations of 60-200 ppm, (2) partially coagulated calcium alginate spheres for absorbing dissolved copper at initial concentrations of 10-40 ppm, and (3) a mixture of green algae Microcystis and sodium alginate dispensed directly into the reactor fluid. The recovery of copper and cobalt, a strategic metal, from cobalt ore leachate was achieved by a two-step approach: direct dispensing of sodium alginate to absorb the bulk of metals followed by the addition of partially coagulated calcium alginate spheres to "polish" the leachate. Metal binding capacity and conditional stability constant of each biopolymer system as well as the effective diffusivity of cupric ion in the matrix of biopolymer gels are reported.

  11. The role of cobalt ferrite magnetic nanoparticles in medical science.

    Science.gov (United States)

    Amiri, S; Shokrollahi, H

    2013-01-01

    The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Preparation and characterization of copper-doped cobalt oxide electrodes.

    Science.gov (United States)

    Rosa-Toro, A La; Berenguer, R; Quijada, C; Montilla, F; Morallón, E; Vazquez, J L

    2006-11-30

    Cobalt oxide (Co3O4) and copper-doped cobalt oxide (CuxCo(3-x)O4) films have been prepared onto titanium support by the thermal decomposition method. The electrodes have been characterized by different techniques such as cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The effect on the electrochemical and crystallographic properties and surface morphology of the amount of copper in the oxide layer has been analyzed. The XPS spectra correspond to a characteristic monophasic Cu-Co spinel oxides when x is below 1. However, when the copper content exceeds that for the stoichiometric CuCo2O4 spinel, a new CuO phase segregates at the surface. The analysis of the surface cation distribution indicates that Cu(II) has preference for octahedral sites.

  13. Analysis of a case of internal contamination with cobalt radioisotopes.

    Science.gov (United States)

    Vrba, T; Malatova, I; Jurochova, B

    2007-01-01

    Internal contamination by compounds of cobalt radioisotopes occurs time to time at nuclear power plants. Intakes and committed effective doses are estimated by biokinetic models described in ICRP publications. The paper deals with a case of internal contamination of a worker engaged in a maintenance task at NPP Dukovany. In this case significant discrepancy was observed between intakes based on various datasets (whole body counting, analysis of urine and faeces) when default model setting was used. The reason of this phenomenon was searched for. Three different least square methods of fits were used to find out possible effect of a fitting method. The measured data were fitted by set of biokinetic functions, which covered all intake ways (ingestion and inhalation) and types (M, S, different AMADs and different f1) of the contaminant. The biokinetic model of cobalt needs further improvements as to find better agreement between data fit from direct measurements and bioassay.

  14. Poly[tri-μ-aqua-diaqua-μ-phosphonoformato-cobalt(IIsodium

    Directory of Open Access Journals (Sweden)

    Xu-Jian Luo

    2013-06-01

    Full Text Available The title complex, [CoNa(CO5P(H2O5]n, was obtained by reacting sodium phosphonoformate with cobalt nitrate. The complex contains cobalt(II and sodium ions, which are bridged by the O atoms of two aqua ligands. The CoII ion is octahedrally coordinated by three phosphonoformato ligands (one bi- and the other monodentate and by two O atoms from the bridging aqua ligands. The sodium cation is hexacoordinated by six O atoms from four bridging and two terminal aqua ligands. The complex molecules are linked to give a three-dimensional structure by phosphonoformate ligands bridging CoII atoms and water molecules establishing cobalt–sodium bridges. O—H...O hydrogen bonding between the aqua ligands and all O atoms of the phosphonoformato ligand and neighbouring aqua ligands help to consolidate the packing.

  15. COBALT CoOperative Blending of Autonomous Landing Technology

    Science.gov (United States)

    Carson, John M. III; Restrepo, Carolina I.; Robertson, Edward A.; Seubert, Carl R.; Amzajerdian, Farzin

    2016-01-01

    COBALT is a terrestrial test platform for development and maturation of GN&C (Guidance, Navigation and Control) technologies for PL&HA (Precision Landing and Hazard Avoidance). The project is developing a third generation, Langley Navigation Doppler Lidar (NDL) for ultra-precise velocity and range measurements, which will be integrated and tested with the JPL Lander Vision System (LVS) for Terrain Relative Navigation (TRN) position estimates. These technologies together provide navigation that enables controlled precision landing. The COBALT hardware will be integrated in 2017 into the GN&C subsystem of the Xodiac rocket-propulsive Vertical Test Bed (VTB) developed by Masten Space Systems (MSS), and two terrestrial flight campaigns will be conducted: one open-loop (i.e., passive) and one closed-loop (i.e., active).

  16. Obstacle performance of cobalt-enriching crust wheeled mining vehicle

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhong-hua; LIU Shao-jun; XIE Ya

    2006-01-01

    A cobalt-enriching crust mining vehicle with four independent driven wheels was proposed. The influence of center-of-gravity position of mining vehicle on obstacle performance was studied. The results show that the mining vehicle has optimal obstacle performance with center-of-gravity position in the middle of suspension. A virtual prototype based on ADAMS software was built and its obstacle performance was simulated. Simulation results show that the mining vehicle with four independent driven wheels has excellent obstacle performance, the maximum climbing capacity is no less than 30°, the maximal ditch width and shoulder height are no less than wheel radius ofmining vehicle. Thus wheeled mining vehicle is feasible for cobalt-enriching crust commercial mining.

  17. 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)

  18. Fractal characteristics of resource quantity of cobalt crusts and seamount topography, the West Pacific

    Institute of Scientific and Technical Information of China (English)

    ZHANG Weiyan; ZHANG Fuyuan; YANG Kehong; HU Guangdao; YANG Shengxiong; CHENG Yongshou; ZHAO Guojun

    2007-01-01

    This paper presents the fractal distribution of topography of seamounts from the West Pacific and the resource quantity of cobalt crust therein. The cobalt resource quantity has three to four variable fractal dimensions, corre- sponding to the distinct slopes and water depths of the sea- mount. The multiple fractal property of resource quantity may have resulted from various factors, such as types and components of cobalt crusts and ages of oceanic crusts host- ing the seamounts. Individual seamounts display complex topography and quantity of cobalt crust, both in the same and different regions.

  19. Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds

    Science.gov (United States)

    Atwater, James E.; Akse, James R.; Jovanovic, Goran N.; Wheeler, Richard R Jr; Sornchamni, Thana

    2003-01-01

    Porous metallic cobalt spheres have been prepared as high temperature capable media for employment in gradient magnetically assisted fluidization and filtration technologies. Cobalt impregnated alginate beads are first formed by extrusion of an aqueous suspension of Co3O4 into a Co(II) chloride solution. The organic polymer is thermally decomposed yielding cobalt oxide spheres, followed by reduction to the metallic state, and densification. Cobalt beads have been produced with porosities ranging between 10 and 50%, depending upon sintering conditions. The product media have been characterized by scanning electron microscopy (SEM), nitrogen adsorption porosimetry, and vibrating sample magnetometry. c2003 Elsevier Science Ltd. All rights reserved.

  20. Justification sequence dissolution of cobalt and nickel mineral by unconventional thermodynamic method

    Directory of Open Access Journals (Sweden)

    Khabibulla Ospanov

    2016-03-01

    Full Text Available The article shows the forecasts of different reactivity of the mineral cobalt and nickel and the choice of effective reagents for opening minerals cobalt and nickel, copper and other metals from cobalt-nickel containing raw materials using unconventional thermodynamic method, in particular, the average atomic formation energy of minerals ∆rG° and the reduced value of new chemical affinity of reaction oxidation ΔrG°/n. These studies allow to choose of the optimal conditions for the dissolution of minerals cobalt and nickel with the least expenditure of time.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Review and Prospect of Cobalt-60 Digital Radiography Inspection Technology

    OpenAIRE

    AN Ji-gang

    2015-01-01

    This article is a review and prospect of the research, development and industrialization of Cobalt-60 digital radiography inspection technology based on the national requirements in the recent 20 years, which is leaded by Institute of Nuclear and New Energy Technology (INET) of TsinghuaUniversity. The research purpose, innovative approach and main academic achievements of this technology were described systematically. The industrial equipment varieties, performance, running condition and appl...

  6. Magnetization distribution in paramagnetic nickel and cobalt oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kernavanois, N.; Ressouche, E.; Brown, P.J.; Henry, J.Y.; Lelievre-Berna, E

    2004-07-15

    Unpolarized and polarized neutron-diffraction have been used on single crystals to study the magnetization distribution in the paramagnetic phase of nickel oxide NiO and cobalt oxide CoO. Highly accurate magnetic structure factors have been measured using the classical polarized beam technique. A detailed description of the magnetization distribution is presented, and compared to the previous results obtained in the ordered state.

  7. Electromagnetic absorption properties of flowerlike cobalt composites at microwave frequencies

    Institute of Scientific and Technical Information of China (English)

    Liu Tao; Zhou Pei-Heng; Liang Di-Fei; Deng Long-Jiang

    2012-01-01

    In this work,we report the electromagnetic absorption(EMA)properties of composites consisting of micrometersized cobalt with flowerlike architecture synthesized by a facile hydrothermal reduction method.Compared with the conventional spherical Co-paraffin composites,the flowerlike Co-paraffin composites are favorable with respect to EMA performance in the low frequency region,ascribing interfacial polarization loss and Ohmic loss to the improvement in the impedance match.

  8. 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. 

  9. Cobalt-catalyzed formation of symmetrical biaryls and its mechanism.

    Science.gov (United States)

    Moncomble, Aurélien; Le Floch, Pascal; Gosmini, Corinne

    2009-01-01

    Effective devotion: An efficient cobalt-catalyzed method devoted to the formation of symmetrical biaryls is described avoiding the preparation of organometallic reagents. Various aromatic halides functionalized by a variety of reactive group reagents are employed. Preliminary DFT calculations have shown that the involvement of a Co(I)/Co(III) couple is realistic at least in the case of 1,3-diazadienes as ligands (FG = functional group).

  10. Cobalt Nanocrystals as Starting Materials for Shape Modificationand Assembly Formation

    Energy Technology Data Exchange (ETDEWEB)

    Erdonmez, Can Kerem [Univ. of California, Berkeley, CA (United States)

    2005-01-01

    Surfactant-coated cobalt nanocrystals can be prepared with areasonable degree of control over particle size and shape using athermolytic route. The small crystallite size, enhanced reactivity andtunable interparticle interactions enable use of this material asstarting material for demonstration of achievement of novel structuresusing extremely simple solution-based approaches. In particular,formation of hollow cobalt sulfide nanocrystals upon chemicalmodification and emergence of long-range orientational order upondrying-mediated assembly of cobalt nanocrystals is reportedhere.Colloidal preparation of Co nanocrystals has been well-studied.Here, we emphasize general principles and crystallographic/morphologicalcharacterization of disk-shaped hcp-Co nanocrystals. Use of surfactantmolecules enables achievement of multiple morphologies in one syntheticsystem.Formation of hollow structures upon in-solution sulfidation of Conanocrystals is presented and discussed. A Kirkendall-type effect,involving dominant outward mass transport during formation of the ionicshell material explains the results naturally. It is expected that thisphenomenon will generalize extensively to formation of hollow structuresof an enormous variety of compositions. Detailed study of particlemorphology as a function of reaction conditions suggest phenomena likelyto be generally relevant to use of this approach. A short report ofcrystallographic co-alignment into vortex-like structures is alsoprovided. Our current best picture of this process involves an interplayof packing and magnetic interactions between facetedparticles.

  11. Origin of electron disproportionation in metallic sodium cobaltates

    Science.gov (United States)

    Lysogorskiy, Y. V.; Krivenko, S. A.; Mukhamedshin, I. R.; Nedopekin, O. V.; Tayurskii, D. A.

    2016-11-01

    Recently, an unusual metallic state with a substantially nonuniform distribution of the charge and magnetic density in CoO2 planes was found experimentally in the NaxCoO2 compound with x >0.6 . We have investigated the origin of such an electron disproportionation in the lamellar sodium cobaltates by calculating the ion states as a function of the strength of the electron correlations in the d (Co) shells within the GGA+U approximation for a system with a realistic crystal structure. It was found that the nonuniformity of spin and charge densities are induced by an ordering of the sodium cations and enhanced correlations. Two important magnetic states of cobalt lattice competing with each other at realistic values of the correlation parameter were found—low-spin hexagons lattice (LS) and higher-spin kagome lattice (HS-KSL). In the heterogeneous metallic HS-KSL phase, magnetic Co ions form a kagome structure. In LS phase, the kagome pattern is decomposed into hexagons and the Co ions possess the minimal values of their spin. Coexistence of these states could explain the emergence of the disproportionation with the peculiar kagome structure experimentally revealed in previous studies of the cobaltates.

  12. 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.

  13. Single DNA Condensation Induced by Hexammine Cobalt with Molecular Combing

    Institute of Scientific and Technical Information of China (English)

    Gao-ming Hu; Yu Lin; Shi-yong Ran; Yan-wei Wang; Guang-can Yang

    2012-01-01

    We investigated the interaction between DNA and hexammine cobalt Ⅲ [Co(NH3)6]3+ by a simple molecular combing method and dynamic light scattering.The average extension of λ-DNA-YOYO-1 complex is found to be 20.9 μm,about 30% longer than the contour length of the DNA in TE buffer (10 mmol/L Tris,1 mmol/L EDTA,pH=8.0),due to bis-intercalation of YOYO-1.A multivalent cation,hexammine cobalt,is used for DNA condensation.We find that the length of DNA-[Co(NH3)6]3+ complexes decrease from 20.9 μm to 5.9 μm as the concentration of the [Co(NH3)6]3+ vary from 0 to 3 μmol/L.This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt.The results from the molecular combing studies are supported by dynamic light scattering investigation,where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions.It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules.

  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. Magnetoelastic coupling in epitaxial cobalt ferrite/barium titanate heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gräfe, Joachim; Welke, Martin [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany); Bern, Francis; Ziese, Michael [Institut für Experimentelle Physik II, Universität Leipzig, Linnéstraße 5, 04103 Leipzig (Germany); Denecke, Reinhard, E-mail: denecke@uni-leipzig.de [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany)

    2013-08-15

    Ultra-thin cobalt ferrite films have been synthesised on ferroelectric barium titanate crystals. The cobalt ferrite films exhibit a magnetic response to strain induced by structural changes in the barium titanate substrate, suggesting a pathway to multiferroic coupling. These structural changes are achieved by heating through the phase transition temperatures of barium titanate. In addition the ferromagnetic signal of the substrate itself is taken into account, addressing the influence of impurities or defects in the substrate. The cobalt ferrite/barium titanate heterostructure is a suitable oxidic platform for future magnetoelectric applications with an established ferroelectric substrate and widely tuneable magnetic properties by changing the transition metal in the ferrite film. - Highlights: ► Ultra-thin CoFe{sub 2}O{sub 4} films grown on ferroelectric BaTiO{sub 3} crystals by PLD. ► Magnetic response to structural changes of BaTiO{sub 3} at transition temperatures. ► Significant magneto-elastic coupling of in-plane magnetisation in SQUID experiments. ► Clear distinction between contribution by BaTiO{sub 3} substrate and by CoFe{sub 2}O{sub 4} film.

  16. Water oxidation using a cobalt monolayer prepared by underpotential deposition.

    Science.gov (United States)

    Marsh, David A; Yan, Wenbo; Liu, Yu; Hemminger, John C; Penner, Reginald M; Borovik, A S

    2013-11-26

    Development of electrocatalysts for the conversion of water to dioxygen is important in a variety of chemical applications. Despite much research in this field, there are still several fundamental issues about the electrocatalysts that need to be resolved. Two such problems are that the catalyst mass loading on the electrode is subject to large uncertainties and the wetted surface area of the catalyst is often unknown and difficult to determine. To address these topics, a cobalt monolayer was prepared on a gold electrode by underpotential deposition and used to probe its efficiency for the oxidation of water. This electrocatalyst was characterized by atomic force microscopy, grazing-incidence X-ray diffraction, and X-ray photoelectron spectroscopy at various potentials to determine if changes occur on the surface during catalysis. An enhancement of current was observed upon addition of PO4(3-) ions, suggesting an effect from surface-bound ligands on the efficiency of water oxidation. At 500 mV overpotential, current densities of 0.20, 0.74, and 2.4 mA/cm(2) for gold, cobalt, and cobalt in PO4(3-) were observed. This approach thus provided electrocatalysts whose surface areas and activity can be accurately determined.

  17. Optical properties of cobalt xanthate films on different substrates

    Institute of Scientific and Technical Information of China (English)

    A Kariper; T zpozan

    2014-01-01

    Cobalt isopropyl xanthate thin films (CXTFs) were deposited via chemical bath deposition onto different substrates:commercial glass (CG), indium tin oxide (ITO), and poly(methyl methacrylate) (PMM). Isopropyl xanthate was synthesized according to a method de-scribed in the literature. The cobalt nitrate and isopropyl xanthate were mixed in a beaker, which allowed the thin films to be deposited via a simple ion–ion mechanism. The transmission, reflectivity, refractive index, dielectric constant, and optical conductivity were investigated for various thin films coated onto different substrates. An ultraviolet-visible spectrophotometer was used to measure the optical properties of the thin films. The lowest value of the transmission and the highest value of the refractive index were observed for the thin films deposited onto PMM. The structure of the cobalt xanthate was characterized by Fourier transform infrared (FTIR) spectroscopy, which was measured using a Perkin−Elmer Spectrum 400 spectrometer. The stretching vibration of the Co–S bonds was observed at 359 cm−1 in the FTIR spectrum of the CXTFs.

  18. Lattice strain induced magnetism in substituted nanocrystalline cobalt ferrite

    Science.gov (United States)

    Kumar, Rajnish; Kar, Manoranjan

    2016-10-01

    Strontium (Sr) substituted cobalt ferrite i.e. Co1-xSrxFe2O4 (x=0.00, 0.01, 0.015, 0.02, 0.05, 0.1) have been synthesized by the citric acid modified sol-gel method. Crystal structure and phase purity have been studied by the X-ray powder diffraction technique. The Rietveld refinement of XRD pattern using the space group Fd 3 bar m shows monotonically increasing of lattice parameter with the increase in Sr concentration. Magnetic hysteresis loops measurement has been carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of ±1.5 T. Magnetocrystalline anisotropy constant were calculated by employing the Law of Approach (LA) to the saturation. It is observed that magnetocrystalline anisotropy has anomaly for x=0.01 (Co0.99Sr0.01Fe2O4) sample. Strain mediated modification of magnetic properties in Sr substituted cobalt ferrite has been observed. The saturation magnetization for doping concentration i.e. x=0.01 abruptly increase while for x>0.01 decreases with the increase in Sr concentration. A correlation between lattice strain and magnetic behavior in non-magnetic Sr- substituted nano-crystalline cobalt ferrite has been reported.

  19. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  20. Limiting Skepticism

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Symons, John

    2011-01-01

    Skeptics argue that the acquisition of knowledge is impossible given the standing possibility of error. We present the limiting convergence strategy for responding to skepticism and discuss the relationship between conceivable error and an agent’s knowledge in the limit. We argue that the skeptic...

  1. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  2. Thermal decomposition and cobalt species transformation of carbon nanotubes supported cobalt catalyst for Fischer-Tropsch synthesis

    Institute of Scientific and Technical Information of China (English)

    Jing Lü; Chengdu Huang; Suli Bai; Yunhui Jiang; Zhenhua Li

    2012-01-01

    The effect of calcination condition on the cobalt species and Fischer-Tropsch synthesis (FTS) was studied.It was found that higher calcination temperature resulted in decreased FTS activities because CNTs were consumed by oxidation in air at temperature higher than 230 ℃.Cobalt species went through transformation from Co3O4 to metallic Co in Ar by autoreduction at temperature over 500 ℃.The autoreduction route might be Co3O4→CoO→Co or Co3O4→Co2C→Co.Reduction at temperature higher than 500 ℃ also resulted in decreased FTS activities due to the methanation of CNTs in hydrogen.

  3. Inverse Limits

    CERN Document Server

    Ingram, WT

    2012-01-01

    Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

  4. 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.

  5. 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)

  6. Effect of cobalt supplementation and fractionation on the biological response in the biomethanization of Olive Mill Solid Waste.

    Science.gov (United States)

    Pinto-Ibieta, F; Serrano, A; Jeison, D; Borja, R; Fermoso, F G

    2016-07-01

    Due to the low trace metals concentration in the Olive Mill Solid Waste (OMSW), a proposed strategy to improve its biomethanization is the supplementation of key metals to enhance the microorganism activity. Among essential trace metals, cobalt has been reported to have a crucial role in anaerobic degradation. This study evaluates the effect of cobalt supplementation to OMSW, focusing on the connection between fractionation of cobalt in the system and the biological response. The highest biological responses was found in a range from 0.018 to 0.035mg/L of dissolved cobalt (0.24-0.65mg total cobalt/L), reaching improvements up to 23% and 30% in the methane production rate and the methane yield coefficient, respectively. It was found that the dissolved cobalt fraction is more accurately related with the biological response than the total cobalt. The total cobalt is distorted by the contribution of dissolved and non-dissolved inert fractions.

  7. Lithium/cobalt sulfide pulse power battery

    Science.gov (United States)

    Seiger, Harvey N.

    The author describes a bipolar battery having a Li alloy anode, CoS2 cathode material, and electrolyte of mixed Li halides. The system is semi-dry because the amount of electrolyte is limited. Fundamental investigations to determine operating voltage limits, active material utilizations, capacity ratios, states of charge, and capacity reserves need to be determined in semi-dry conditions to be unequivocal. This requirement precludes a reference electrode and, instead, the function of a counter-electrode and reference electrodes were combined. The author describes methods and shows comparisons with literature voltammetry data and use of galvanostatic procedures. The results obtained with several Li alloys and with CoS2 electrodes are discussed along with application of these electrochemical design of pulse batteries.

  8. 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.

  9. Cobalt carbide nanoprisms for direct production of lower olefins from syngas.

    Science.gov (United States)

    Zhong, Liangshu; Yu, Fei; An, Yunlei; Zhao, Yonghui; Sun, Yuhan; Li, Zhengjia; Lin, Tiejun; Lin, Yanjun; Qi, Xingzhen; Dai, Yuanyuan; Gu, Lin; Hu, Jinsong; Jin, Shifeng; Shen, Qun; Wang, Hui

    2016-10-06

    Lower olefins-generally referring to ethylene, propylene and butylene-are basic carbon-based building blocks that are widely used in the chemical industry, and are traditionally produced through thermal or catalytic cracking of a range of hydrocarbon feedstocks, such as naphtha, gas oil, condensates and light alkanes. With the rapid depletion of the limited petroleum reserves that serve as the source of these hydrocarbons, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The 'Fischer-Tropsch to olefins' (FTO) process has long offered a way of producing lower olefins directly from syngas-a mixture of hydrogen and carbon monoxide that is readily derived from coal, biomass and natural gas. But the hydrocarbons obtained with the FTO process typically follow the so-called Anderson-Schulz-Flory distribution, which is characterized by a maximum C2-C4 hydrocarbon fraction of about 56.7 per cent and an undesired methane fraction of about 29.2 per cent (refs 1, 10, 11, 12). Here we show that, under mild reaction conditions, cobalt carbide quadrangular nanoprisms catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (constituting around 60.8 per cent of the carbon products), while generating little methane (about 5.0 per cent), with the ratio of desired unsaturated hydrocarbons to less valuable saturated hydrocarbons amongst the C2-C4 products being as high as 30. Detailed catalyst characterization during the initial reaction stage and theoretical calculations indicate that preferentially exposed {101} and {020} facets play a pivotal role during syngas conversion, in that they favour olefin production and inhibit methane formation, and thereby render cobalt carbide nanoprisms a promising new catalyst system for directly converting syngas into lower olefins.

  10. Cobalt carbide nanoprisms for direct production of lower olefins from syngas

    Science.gov (United States)

    Zhong, Liangshu; Yu, Fei; An, Yunlei; Zhao, Yonghui; Sun, Yuhan; Li, Zhengjia; Lin, Tiejun; Lin, Yanjun; Qi, Xingzhen; Dai, Yuanyuan; Gu, Lin; Hu, Jinsong; Jin, Shifeng; Shen, Qun; Wang, Hui

    2016-10-01

    Lower olefins—generally referring to ethylene, propylene and butylene—are basic carbon-based building blocks that are widely used in the chemical industry, and are traditionally produced through thermal or catalytic cracking of a range of hydrocarbon feedstocks, such as naphtha, gas oil, condensates and light alkanes. With the rapid depletion of the limited petroleum reserves that serve as the source of these hydrocarbons, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The ‘Fischer-Tropsch to olefins’ (FTO) process has long offered a way of producing lower olefins directly from syngas—a mixture of hydrogen and carbon monoxide that is readily derived from coal, biomass and natural gas. But the hydrocarbons obtained with the FTO process typically follow the so-called Anderson-Schulz-Flory distribution, which is characterized by a maximum C2-C4 hydrocarbon fraction of about 56.7 per cent and an undesired methane fraction of about 29.2 per cent (refs 1, 10, 11, 12). Here we show that, under mild reaction conditions, cobalt carbide quadrangular nanoprisms catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (constituting around 60.8 per cent of the carbon products), while generating little methane (about 5.0 per cent), with the ratio of desired unsaturated hydrocarbons to less valuable saturated hydrocarbons amongst the C2-C4 products being as high as 30. Detailed catalyst characterization during the initial reaction stage and theoretical calculations indicate that preferentially exposed {101} and {020} facets play a pivotal role during syngas conversion, in that they favour olefin production and inhibit methane formation, and thereby render cobalt carbide nanoprisms a promising new catalyst system for directly converting syngas into lower olefins.

  11. Sequential determination of lead and cobalt in tap water and foods samples by fluorescence.

    Science.gov (United States)

    Talio, María Carolina; Alesso, Magdalena; Acosta, María Gimena; Acosta, Mariano; Fernández, Liliana P

    2014-09-01

    In this work, a new procedure was developed for the separation and preconcentration of lead(II) and cobalt(II) in several water and foods samples. Complexes of metal ions with 8-hydroxyquinolein (8-HQ) were formed in aqueous solution. The proposed methodology is based on the preconcentration/separation of Pb(II) by solid-phase extraction using paper filter, followed by spectrofluorimetric determination of both metals, on the solid support and the filtered aqueous solution, respectively. The solid surface fluorescence determination was carried out at λem=455 nm (λex=385 nm) for Pb(II)-8-HQ complex and the fluorescence of Co(II)-8-HQ was determined in aqueous solution using λem=355 nm (λex=225 nm). The calibration graphs are linear in the range 0.14-8.03×10(4) μg L(-1) and 7.3×10(-2)-4.12×10(3) μg L(-1), for Pb(II) and Co(II), respectively, with a detection limit of 4.3×10(-2) and 2.19×10(-2) μg L(-1) (S/N=3). The developed methodology showed good sensitivity and adequate selectivity and it was successfully applied to the determination of trace amounts of lead and cobalt in tap waters belonging of different regions of Argentina and foods samples (milk powder, express coffee, cocoa powder) with satisfactory results. The new methodology was validated by electrothermal atomic absorption spectroscopy with adequate agreement. The proposed methodology represents a novel application of fluorescence to Pb(II) and Co(II) quantification with sensitivity and accuracy similar to atomic spectroscopies.

  12. Copper(II)-8-hydroxquinoline coprecipitation system for preconcentration and separation of cobalt(II) and manganese(II) in real samples.

    Science.gov (United States)

    Soylak, Mustafa; Kaya, Betul; Tuzen, Mustafa

    2007-08-25

    A separation-preconcentration procedure based on the coprecipitation of cobalt(II) and manganese(II) ions with copper(II)-8-hydroxquinoline system has been developed. The analytical parameters including pH, amount of copper(II) as carrier element, amount of 8-hydroxquinoline, sample volume, etc., was investigated for the quantitative recoveries of Co(II) and Mn(II). No interferic effects were observed from the concomitant ions which are present in real samples. The detection limits for analyte ions by three sigma criteria were 0.86microgL(-1) for cobalt and 0.98microgL(-1) for manganese. The validation of the presented preconcentration procedure was performed by the analysis of NIST SRM 2711 Montana soil and GBW 07605 Tea certified reference materials. The procedure presented was applied to the analyte contents of real samples including natural waters and some food samples with successfully analytical results.

  13. Controlled Growth of Nanostructured Biotemplates with Cobalt and Nitrogen Codoping as a Binderless Lithium-Ion Battery Anode.

    Science.gov (United States)

    Huggins, Tyler M; Whiteley, Justin M; Love, Corey T; Lee, Kwangwon; Lee, Se-Hee; Ren, Zhiyong Jason; Biffinger, Justin C

    2016-10-12

    Biomass can serve as a sustainable template for the synthesis of carbon materials but is limited by the intrinsic properties of the precursor organism. In this study we demonstrate that the properties of a fungal biotemplate can be tuned during cultivation, establishing a new electrode manufacturing process and ultimately improving the electrochemical performance of the biomass-derived electrode. More specifically, the carbon/nitrogen ratio of Neurospora crassa mycelia mats was shifted by 5-fold while generating cobalt nanoparticles into the hyphal structure originating from macroconidia spores. This shift was achieved through nitrate limitation and equal molar concentrations of Mg(2+) and Co(2+) in the growth media. The resulting mycelia mat was converted via a high-temperature pyrolysis process (800 °C) to produce a freestanding cobalt and nitrogen codoped electrode material with no postmodification. Ultimately, nitrogen doping resulted in one of the highest recorded specific reversible capacity for a freestanding biomass-derived lithium-ion anode (400 mAh g(-1) at C/10). We observed an additional improvement in capacity to 425 mAh g(-1) with the incorporation of 3 wt % Co. Our results show how shaping the chemical characteristics of an electrode during the growth of the biotemplate allows for sustainable carbon-based material manufacturing from a living (self-assembled) material.

  14. Contribution to the study of external contamination by radioactive products: skin contamination by radioactive cobalt in soluble form and decontamination; Contribution a l'etude de la contamination externe par des produits radioactifs: contamination cutanee par les cobalts radioactifs sous forme soluble et decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Tymen, H.

    2002-12-15

    The aim of this work was to characterize the behavior of the radioactive cobalt isotopes, which are present in reactor coolant systems of a pressurized water reactor (PWR), in the case of occupational skin exposure, and to study different therapies. Our experimental approach stems from standardized methods in skin pharmacology. In a first step, a physico-chemical study of a primary coolant water was carried out to characterize the soluble fraction of radio-cobalt and its skin affinity. The second step consisted in quantifying the diffusion through the skin, in vivo and in vitro in rats, and in vitro in human. Parallel experiments were carried out to study biokinetics of cobalt in rats, after intravenous, intramuscular and subcutaneous injection. Whatever the route of administration, cobalt diffuses easily in the organism. On the contrary, its skin absorption is very limited. In a fourth step, the influence of the skin injuries on absorption was estimated in vivo on rat skin. Several skin models were developed to standardize different injuries: excoriation, heat burns (convection, conduction) and chemical burns (acid or alkaline). Biokinetics study over 24 hours and histological study have shown a relation between skin absorption and stratum corneum alteration. In the latest step of this work, we compared the efficacy of various decontaminating agents administered under different galenic forms. Per (3, 6- anhydro, 2-O-carboxy-methyl)-{alpha}-cyclo-dextrin exhibited a significant efficacy for cobalt decontamination of skin. This macromolecule was tested in aqueous solution, in agarose gel and loaded on 'functionalized' fibers intended for development of new decontaminating tissues. (author)

  15. 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...

  16. Effect of vitamin B-12 pulse addition on the performance of cobalt deprived anaerobic granular sludge bioreactors

    NARCIS (Netherlands)

    Fermoso, F.G.; Bartacek, J.; Lens, P.N.L.

    2010-01-01

    The effect of a pulse addition of vitamin B-12 as cobalt source to restore the performance of cobalt depleted methanol-fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was supplied with a pulse of vitamin B-12, and its operation was compared to that of another cobalt

  17. Effect of vitamin B-12 pulse addition on the performance of cobalt deprived anaerobic granular sludge bioreactors

    NARCIS (Netherlands)

    Fermoso, F.G.; Bartacek, J.; Lens, P.N.L.

    2010-01-01

    The effect of a pulse addition of vitamin B-12 as cobalt source to restore the performance of cobalt depleted methanol-fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was supplied with a pulse of vitamin B-12, and its operation was compared to that of another cobalt

  18. 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....

  19. 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...

  20. Catalytic hydrogenation of carbon monoxide to alkenes over partially degraded iron-cobalt complexes

    NARCIS (Netherlands)

    Snel, R.

    1989-01-01

    Complex-derived iron-cobalt alloy catalysts have been studied under conditions similar to those normally prevailing in industry. Despite reports in the literature indicating unusual selectivities with iron-cobalt alloy catalysts under atmospheric pressure conditions, no deviations from normal select

  1. 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 The Vickers hardness of WC-Co alloys has been measured at temperatures ranging from -196 to 900 degrees C. The cobalt content of the alloys ranged from 10 to 24 vol% and the grain size from 0.5 to 2.3 um. It was found that, at all cobalt contents...

  2. Self-subunit swapping occurs in another gene type of cobalt nitrile hydratase.

    Directory of Open Access Journals (Sweden)

    Yi Liu

    Full Text Available 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.

  3. Imprint of a dissolved cobalt basaltic source on the Kerguelen Plateau

    NARCIS (Netherlands)

    Bown, J.; Boye, M.; Laan, P.; Bowie, A.R.; Park, Y.H.; Jeandel, C.; Nelson, D.M.

    2012-01-01

    Processes of cobalt (Co) entrainment from shelf sediments over the Kerguelen Plateau were studied during the KEOPS (Kerguelen Ocean Plateau compared Study) in order to explain the exceptionally high dissolved cobalt concentrations that have been measured in the surface waters above the Kerguelen Pla

  4. The impact of rare earth cobalt permanent magnets on electromechanical device design

    Science.gov (United States)

    Fisher, R. L.; Studer, P. A.

    1979-01-01

    Specific motor designs which employ rare earth cobalt magnets are discussed with special emphasis on their unique properties and magnetic field geometry. In addition to performance improvements and power savings, high reliability devices are attainable. Both the mechanism and systems engineering should be aware of the new performance levels which are currently becoming available as a result of the rare earth cobalt magnets.

  5. Interaction of zinc and cobalt with dipeptides and their DNA binding studies

    Indian Academy of Sciences (India)

    P Rabindra Reddy; M Radhika; K Srinivas Rao

    2004-06-01

    Interactions of zinc and cobalt with peptides cysteinylglycine and histidylglycine have been studied. The binding modes were identified and geometry assigned. Stabilities of these complexes and their ability to bind DNA have been investigated. It is demonstrated that only zinc complexes bind DNA as compared to cobalt complexes.

  6. Evaluation of transgenic tobacco plants expressing a bacterial Co-Ni transporter for acquisition of cobalt.

    Science.gov (United States)

    Nair, Smitha; Joshi-Saha, Archana; Singh, Sudhir; Ramachandran, V; Singh, Surya; Thorat, Vidya; Kaushik, C P; Eapen, Susan; D'Souza, S F

    2012-11-15

    Phytoremediation is a viable strategy for management of toxic wastes in a large area/volume with low concentrations of toxic elemental pollutants. With increased industrial use of cobalt and its alloys, it has become a major metal contaminant in soils and water bodies surrounding these industries and mining sites with adverse effects on the biota. A bacterial Co-Ni permease was cloned from Rhodopseudomonas palustris and introduced into Nicotiana tabacum to explore its potential for phytoremediation and was found to be specific for cobalt and nickel. The transgenic plants accumulated more cobalt and nickel as compared to control, whereas no significant difference in accumulation of other divalent ions was observed. The transgenic plants were evaluated for cobalt content and showed increased acquisition of cobalt (up to 5 times) as compared to control. The plants were also assessed for accumulation of nickel and found to accumulate up to 2 times more nickel than control. At the same initial concentration of cobalt and nickel, transgenic plant preferentially accumulated cobalt as compared to nickel. The present study is perhaps the first attempt to develop transgenic plants expressing heterologous Co transporter with an improved capacity to uptake cobalt. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Development of Black Cobalt Selective Absorber on Copper for Solar Collectors

    OpenAIRE

    KADIRGAN, Figen

    2014-01-01

    An eletrolyte is proposed for the deposition of black cobalt selective absorber coating on copper plate. The influence of the electrolyte composition and operating parameters on the properties of black cobalt coatings including optical properties were studied. The optimum conditions to obtain a high absorptance/emittance ratio are described.

  8. 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...

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

    NARCIS (Netherlands)

    den Breejen, Johan P.; Frey, Anne M.; Yang, Jia; Holmen, Anders; van Schooneveld, Matti M.; de Groot, Frank M. F.; Stephan, Odile; Bitter, Johannes H.; de Jong, Krijn P.

    2011-01-01

    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 cat

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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 fra

  15. 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 fra

  16. 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)

  17. 77 FR 3750 - Notice of Intent To Grant a Partially Exclusive License; Cobalt Technologies, Inc.

    Science.gov (United States)

    2012-01-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Navy Notice of Intent To Grant a Partially Exclusive License; Cobalt Technologies, Inc... notice of its intent to grant to Cobalt Technologies, Inc., a revocable, nonassignable, partially...

  18. 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

  19. L-Ascorbic Acid Protected Against Extrinsic and Intrinsic Apoptosis Induced by Cobalt Nanoparticles Through ROS Attenuation.

    Science.gov (United States)

    Liu, Yake; Hong, Hongxiang; Lu, Xu; Wang, Wei; Liu, Fan; Yang, Huilin

    2017-02-01

    Currently, tissue damage induced by cobalt nanoparticles (CoNPs) and cobalt ions (Co(2+)) are the most serious syndrome in the patients with metal-on-metal hip prostheses. Therefore, an urgent need exists for the identification of the mechanisms and the development of therapeutic strategies to limit it. The purpose of this study was to explore the mechanism of this damage and to demonstrate if L-ascorbic acid (L-AA) could protect against the cell toxicities induced by CoNPs and Co(2+) in vitro. With CoNPs and Co(2+) treatment, cell viability was significantly decreased; the ROS (reactive oxygen species) level in mitochondria was dramatically increased in CoNPs treated cells, but cobalt ions could barely induce the ROS. Consistently, the level of cell apoptosis was increased with the upregulation of pro-apoptotic factors (caspases 8, 9, and 3, and Bax) and the downregulation of anti-apoptotic factor Bcl-2. Besides that, the levels of cytochrome c and AIF were increased and released from mitochondria into the cytoplasm. After the cells were pretreated with L-AA, the cell viability decreased by CoNPs was reversed and the ROS induced by CoNPs was suppressed. The level of cell apoptosis induced by CoNPs was decreased as well. But it could not reverse the effects induced by Co(2+). These studies demonstrated that CoNPs induce extrinsic and intrinsic apoptotic pathways via generation of ROS, and L-AA could prevent the cytotoxicity by reducing the level of ROS. While Co(2+) may induce cytotoxicity through other signals, it could not be protected by L-AA treatment.

  20. An hydrothermal experimental study of the cobalt-cobalt oxide redox buffer

    Science.gov (United States)

    Lemke, K.H.; Rosenbauer, R.J.; Bischoff, J.L.; Bird, D.K.

    2008-01-01

    Equilibrium aqueous hydrogen concentration and corresponding energies of reaction, ??Grxno(T, P), for the reaction Co(s) + H2O(l) = CoO(s) + H2(aq) have been determined at temperatures between 256 and 355 ??C and at 400 bar. Steady-state concentrations of hydrogen were approached in experiments under conditions of both H2 excess and deficiency containing the solids Co, CoO and liquid water. All experiments were carried out in flexible gold and titanium reactors with the capability of on-line fluid sampling. Measured equilibrium molal concentrations of H2(aq) at 256, 274, 300, 324 and 355 ??C are 0.81(?? 0.01) ?? 10- 3 1.11(?? 0.01) ?? 10- 3, 1.92(?? 0.01) ?? 10- 3, 3.71(?? 0.06) ?? 10- 3, 7.54(?? 0.12) ?? 10- 3, respectively, and corresponding values of ??Grxno(T, P) in units kJ ?? mol- 1 are 31.4(?? 0.1), 31.0(?? 0.1), 29.8(?? 0.1), 27.7(?? 0.5) and 25.5(?? 0.9), respectively. Using published heat capacity data for Co(s) and CoO(s) and - 79.6 J ?? mol- 1 ?? K- 1 for the entropy of formation of CoO we calculated for this study a value for ??GCoO,Tr,Pro = - 214.5(?? 0.9) kJ ?? mol- 1 and ??HCoO,Tr,Pro = - 238.3(?? 0.9) kJ ?? mol- 1 at 25 ??C and 1 bar. The value of ??HCoO,Tr,Pro determined in this study compares well with the reported calorimetric value of - 238.9(?? 1.2) kJ ?? mol- 1 [Boyle, B.J., King, E.G., Conway, K.C., 1954. Heats of formation of nickel and cobalt oxides (NiO and CoO) by combustion calorimetry. Journal of the American Chemical Society, 76, 3835-3837]. ?? 2008 Elsevier B.V. All rights reserved.

  1. Scientific Opinion on safety and efficacy of coated granulated cobaltous carbonate monohydrate as feed additive for all species

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed

    2012-07-01

    Full Text Available

    Cobalt(III is a component of cobalamin. Its essentiality as trace element results from the capacity of certain animal species to synthesise cobalamin by the gastrointestinal microbiota. Feeding cobalt(II carbonate hydroxide (2:3 monohydrate up to the maximum authorised total cobalt in feed is safe for the target animals. Cobalt is predominantly excreted via the faecal route. Absorbed cobalt follows aqueous excretion routes. About 43 % of body cobalt is stored in muscle; however, kidney and liver are the edible tissues containing the highest cobalt concentrations and are most susceptible to reflect dietary cobalt concentrations. In animals with the capacity to synthesise cobalamin, cobalt is also deposited in tissues as vitamin B12. Cobalt(II cations are genotoxic under in vitro and in vivo conditions. Cobalt(II carbonate has carcinogen, mutagen and reproduction toxicant (CMR properties. No data are available on the potential carcinogenicity of cobalt(II following oral exposure. However, oral exposure may potentially entail adverse threshold-related effects in humans. The estimated population intake of cobalt most likely includes the contribution of foodstuffs from animals fed cobalt-supplemented feedingstuffs. An increase in cobalt exposure by the use of cobalt-containing feed additives is therefore not expected. Considering the population exposure to cobalt, about 4–10 times lower than the health-based guidance value, no safety concern for the consumer is expected for threshold effects of oral cobalt. Cobalt(II carbonate is a skin and eye irritant, and a dermal and respiratory sensitiser. Its dust is a hazard to persons handling the substance. Exposure by inhalation must be avoided. The use of cobalt from any source at the authorised maximum content in feed does not provide a risk to the environment. The coated granulated cobalt(II carbonate hydroxide (2:3 monohydrate is available for cobalamin synthesis in

  2. In situ formation of cobalt oxide nanocubanes as efficient oxygen evolution catalysts.

    Science.gov (United States)

    Hutchings, Gregory S; Zhang, Yan; Li, Jian; Yonemoto, Bryan T; Zhou, Xinggui; Zhu, Kake; Jiao, Feng

    2015-04-01

    Oxygen evolution from water poses a significant challenge in solar fuel production because it requires an efficient catalyst to bridge the one-electron photon capture process with the four-electron oxygen evolution reaction (OER). Here, a new strategy was developed to synthesize nonsupported ultrasmall cobalt oxide nanocubanes through an in situ phase transformation mechanism using a layered Co(OH)(OCH3) precursor. Under sonication, the precursor was exfoliated and transformed into cobalt oxide nanocubanes in the presence of NaHCO3-Na2SiF6 buffer solution. The resulting cobalt catalyst with an average particle size less than 2 nm exhibited a turnover frequency of 0.023 per second per cobalt in photocatalytic water oxidation. X-ray absorption results suggested a unique nanocubane structure, where 13 cobalt atoms fully coordinated with oxygen in an octahedral arrangement to form 8 Co4O4 cubanes, which may be responsible for the exceptionally high OER activity.

  3. 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.

  4. Calorimetric examination of mixtures for modification of nickel and cobalt superalloys

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-04-01

    Full Text Available The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at hightemperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations andmeasurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flourZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possibility of using certainmixtures as potential inoculating additives for the volume modification of nickel and cobalt superalloys. A characteristic feature of these alloys is the formation of a detrimental structure containing very large columnar crystal, present even in castings of a very high solidification rate. It has been proved that the inoculant most effective in the formation of the structure of equiaxial grains is the inoculant based on cobalt aluminate, colloidal silica and powdered aluminium.

  5. 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.

  6. 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.)

  7. Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Ankur Bordoloi

    2014-01-01

    Full Text Available Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.

  8. Comparison of the dietary cobalt intake in three different Australian diets.

    Science.gov (United States)

    Hokin, Bevan; Adams, Michelle; Ashton, John; Louie, Honway

    2004-01-01

    Differences in the dietary intake of cobalt were assessed for vegans, lacto-ovo-vegetarian and non-vegetarian Australians using food intake logs, and daily or average trend recall over three months. A significant decrease in cobalt intake was observed for the lacto-ovo-vegetarian population compared with the intake in vegans and omnivores. There is no RDI for cobalt, however, the cobalt intake of Australians was similar to that reported in other countries. Microflora above the terminal ileum have been shown to produce significant amounts of biologically available vitamin B12. This study was unable to demonstrate a correlation between elemental cobalt intake and serum vitamin B12 concentrations in humans, as has been shown in vitro.

  9. 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

  10. 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.

  11. Propolis attenuates cobalt induced-nephrotoxicity in adult rats and their progeny.

    Science.gov (United States)

    Garoui, El Mouldi; Troudi, Afef; Fetoui, Hamadi; Soudani, Nejla; Boudawara, Tahia; Zeghal, Najiba

    2012-11-01

    The aim of this study was to evaluate the biochemical changes in cobalt-exposed rats and to investigate the potential role of Tunisian propolis against the cobalt-induced renal damages. Twenty-four pregnant Wistar rats were divided into four groups and were treated as follows: group 1 (control) received distilled water; group 2 received 350 ppm of CoCl(2) in drinking water; group 3 received 350 ppm CoCl(2) in drinking water and a propolis-supplemented diet (1 g/100 g of diet); group 4 received a propolis-supplemented diet (1 g/100 g of diet) without cobalt. In the cobalt group, a significant decrease in body, absolute and relative weights was noted when compared to controls. The administration of cobalt to pregnant rats from the 14th day of pregnancy until day 14 after delivery resulted in an increased level of renal malondialdehyde, a decreased renal content of glutathione and antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase in lactating rats and their pups. A statistically significant increase in plasma urea and creatinine serum levels was seen in treated female rats and their pups. Histopathologically, the cobalt-administration induced degenerative changes in the kidney of lactating rats and their pups. When compared with cobalt-treated rats, those receiving the propolis supplementation (along with cobalt-treatment) had lower malondialdehyde levels, higher antioxidant activities and the cobalt-related histopathological changes in the kidneys were at lower severity. Our results suggested that the propolis might be a potential candidate agent against cobalt-induced nephrotoxicity in adult and juvenile rats when administered to female rats during the late pregnancy and the early postnatal period. Copyright © 2011 Elsevier GmbH. All rights reserved.

  12. The effect of cobalt substitution on magnetic hardening of magnetite

    Science.gov (United States)

    Mozaffari, M.; Hadadian, Y.; Aftabi, A.; Oveisy Moakhar, M.

    2014-03-01

    In this work cobalt-substituted magnetite (CoxFe1-xFe2O4, 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.

  13. 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.

  14. Structural study of monolayer cobalt phthalocyanine adsorbed on graphite

    CERN Document Server

    Scheffler, M; Baumann, D; Schlegel, R; Hänke, T; Toader, M; Büchner, B; Hietschold, M; Hess, C

    2014-01-01

    We present microscopic investigations on the two-dimensional arrangement of cobalt phthalocyanine molecules on a graphite (HOPG) substrate in the low coverage regime. The initial growth and ordering of molecular layers is revealed in high resolution scanning tunneling microscopy (STM). On low coverages single molecules orient mostly along one of the substrate lattice directions, while they form chains at slightly higher coverage. Structures with two different unit cells can be found from the first monolayer on. A theoretical model based on potential energy calculations is presented, which relates the two phases to the driving ordering forces.

  15. Size dependence of magnetorheological properties of cobalt ferrite ferrofluid

    Energy Technology Data Exchange (ETDEWEB)

    Radhika, B.; Sahoo, Rasmita; Srinath, S., E-mail: srinath@uohyd.ac.in [School of Physics, University of Hyderabad, Hyderabad-500040 (India)

    2015-06-24

    Cobalt Ferrite nanoparticles were synthesized using co-precipitation method at reaction temperatures of 40°C and 80°C. X-Ray diffraction studies confirm cubic phase formation. The average crystallite sizes were found to be ∼30nm and ∼48nm for 40°C sample and 80°C sample respectively. Magnetic properties measured using vibrating sample magnetometer show higher coercivety and magnetization for sample prepared at 80°C. Magnetorheological properties of CoFe2O4 ferrofluids were measured and studied.

  16. Gas atomization of cobalt ferrite-phosphate melts

    Science.gov (United States)

    De Guire, Mark R.; O'Handley, R. C.; Kalonji, G.

    1989-01-01

    XRD, Moessbauer spectroscopy, and EDXS have been used to characterize a rapidly-solidified (Co,Fe)3O4 spinel generated in a cobalt-iron-phosphate glass matrix by gas atomization of melts. Of the two compositions tested, that containing 20 mol pct P2O5 exhibited randomly-oriented ferrite crystallization whose growth appears to have been diffusion-controlled. Unlike the ferrite, in which the iron has both tetrahedral and octahedral coordination, the iron in the glassy matrix was primarily of distorted-octahedral coordination. Calculations indicate that the cooling rates obtained with oxide melts vary strongly with droplet size, but less strongly with melt temperature.

  17. 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...

  18. Cobalt(Ⅱ)/manganese(Ⅱ)-based molecular metamagnets

    Institute of Scientific and Technical Information of China (English)

    ZHOU YanLing; HU YueQiao; ZENG MingHua

    2012-01-01

    This mini-review covers recent progress in the field of cobalt(Ⅱ)/manganese(Ⅱ)-based molecular metamagnets,which can undergo magnetic phase transitions to a state with a net magnetic moment under the stimulation of external field.We simply discuss mean field theory describing these compounds and the important role of the magnetic anisotropy.The experimental properties of the known Co(Ⅱ)/Mn(Ⅱ)metamagnets are discussed,with emphasis on the variety of means by which the metamagnetic transitions have been observed and studied.

  19. Gas atomization of cobalt ferrite-phosphate melts

    Science.gov (United States)

    De Guire, Mark R.; O'Handley, R. C.; Kalonji, G.

    1989-01-01

    XRD, Moessbauer spectroscopy, and EDXS have been used to characterize a rapidly-solidified (Co,Fe)3O4 spinel generated in a cobalt-iron-phosphate glass matrix by gas atomization of melts. Of the two compositions tested, that containing 20 mol pct P2O5 exhibited randomly-oriented ferrite crystallization whose growth appears to have been diffusion-controlled. Unlike the ferrite, in which the iron has both tetrahedral and octahedral coordination, the iron in the glassy matrix was primarily of distorted-octahedral coordination. Calculations indicate that the cooling rates obtained with oxide melts vary strongly with droplet size, but less strongly with melt temperature.

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

    Science.gov (United States)

    Ge, Qingchun; Fu, Fengjiang; Chung, Tai-Shung

    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 2.0 M produced relatively high water fluxes of 39-48 LMH (L m(-2) hr(-1)) with negligible reverse solute fluxes. A water flux of 17.4 LMH was achieved when model seawater of 3.5 wt.% NaCl replaced DI water as the feed and 2.0 M 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.

  1. Solar selective black nickel-cobalt coatings on aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shashikala, A.R.; Sharma, A.K.; Bhandari, D.R. [Thermal System Group, ISRO Satellite Centre, Bangalore 560 017 (India)

    2007-04-16

    Solar selective black nickel-cobalt plating on pre cleaned aluminum alloy substrates with nickel undercoat were investigated. Process optimization was carried out by the hull cell experiments investigating the influence of operating variables on the optical selectivity of the coating. The coatings were characterized with scanning electron microscope, X-ray diffraction, energy dispersive X-ray spectroscopic and polarization studies. Evaluation of the coatings was carried out by adhesion, measurement of coating thickness and optical properties, humidity, thermal cycling, thermo-vacuum performance and thermal stability tests. (author)

  2. Distribution of platinum and cobalt atoms in a bimetallic nanoparticle

    Science.gov (United States)

    Chui, Yu Hang; Chan, Kwong-Yu

    2005-06-01

    Molecular dynamics simulations are performed to investigate the atomic distribution and the structure of platinum-cobalt nanoparticles. Heating and cooling techniques are applied before getting equilibrated structures at 298 K. Both crystalline (fcc) and amorphous structures are partly observed depending on cooling rates. The atomic distributions in different regions of a bimetallic nanoparticle are analyzed. Although platinum tends to occupy surface and near-surface sites of the bimetallic nanoparticle, a complete segregation to form a core-shell structure is not observed.

  3. Mapping the magnetic and crystal structure in cobalt nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Cantu-Valle, Jesus; Betancourt, Israel; Sanchez, John E.; Ruiz-Zepeda, Francisco; Mendoza-Santoyo, Fernando; Ponce, Arturo, E-mail: arturo.ponce@utsa.edu [Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249 (United States); Maqableh, Mazin M.; Stadler, Bethanie J. H. [Electrical and Computer Engineering, University of Minnesota, 4-174 EE/CSci Bldg., 200 Union St. SE, Minneapolis, Minnesota 55455 (United States)

    2015-07-14

    Using off-axis electron holography under Lorentz microscopy conditions to experimentally determine the magnetization distribution in individual cobalt (Co) nanowires, and scanning precession-electron diffraction to obtain their crystalline orientation phase map, allowed us to directly visualize with high accuracy the effect of crystallographic texture on the magnetization of nanowires. The influence of grain boundaries and disorientations on the magnetic structure is correlated on the basis of micromagnetic analysis in order to establish the detailed relationship between magnetic and crystalline structure. This approach demonstrates the applicability of the method employed and provides further understanding on the effect of crystalline structure on magnetic properties at the nanometric scale.

  4. 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.

  5. Sedimentary cobalt concentrations track marine redox evolution

    Science.gov (United States)

    Swanner, Elizabeth; Planavsky, Noah; Lalonde, Stefan; Robbins, Jamie; Bekker, Andrey; Rouxel, Olivier; Konhauser, Kurt O.; Mojzsis, Stephen J.

    2013-04-01

    Oxygen production by photosynthesis drove the redox evolution of the atmosphere and ocean. Primary productivity by oxygenic photosynthesizers in the modern surface ocean is limited by trace nutrients such as iron, but previous studies have also observed high Co uptake associated with natural cyanobacterial populations. Constraining the size and variation of the oceanic reservoir of Co through time will help to understand the regulation of primary productivity and hence oxygenation through time. In this study, Co concentrations from iron formations (IF), shales and marine pyrites deposited over nearly 4 billion years of Earth's history are utilized to reconstruct secular changes in the mechanisms of Co removal from the oceanic reservoir. The Co reservoir prior to ~2 Ga was dominated by hydrothermal inputs and Fe(III)oxyhydroxides were likely involved in the removal of Co from the water column. Fe(II) oxidation in the water column resulted in the deposition of IF in the Archean and Paleoproterozoic, and the Co inventory of IF records a large oceanic reservoir of Co during this time. Lower Co concentrations in sediments during the Middle Proterozoic signify a decrease in the oceanic reservoir due to the expansion euxinic environments, corresponding to the results of previous studies. A transition to an oxidized deep ocean in the Phanerozoic is evidenced by correlation between Co and manganese (Mn) concentrations in hydrothermal and exhalative deposits, and in marine pyrites. This relationship between Co and Mn, signifying deposition of Co in association with Mn(IV)oxides, does not occur in the Precambrian. Mn(II) oxidation occurs at higher redox potentials than that required for Fe(II) oxidation, and the extent of Mn redox cycling prior to full ventilation of the oceans at the end of the Neoproterozoic was likely limited to spatially restricted oxic surface waters. In this regard, Co is another valuable redox proxy for tracking the growth and decline in oxygenated

  6. Heterogenite vs asbolane: a mineralogical study of cobalt oxides from the DRC (Democratic Republic of the Congo)

    Science.gov (United States)

    Burlet, Christian; Vanbrabant, Yves; Decree, Sophie

    2014-05-01

    The largest cobalt ore reserves are located in DRC, the Democratic Republic of Congo. Most of cobalt is observed as black cobaltic oxide minerals: heterogenite [HCoO2] and asbolane [(Ni,Co)2-xMn(O,OH)4.nH2O] which are hardly differentiable since they exhibit similar macroscopic habit and textures. These minerals are frequently observed in similar environment (oxidized horizon of ore deposits) and they are commonly poorly-crystallized limiting their study with XRD. Their chemical composition is also not very well-constrained since they exhibit significant chemical substitutions with cations as Cu, Co, Ni, Mn. Our observations on a set of heterogenite and asbolane samples from DRC combined with samples from other localities shows that each phase, even under an amorphous form, can be readily distinguished by Raman microspectrometry. This technique is therefore attractive during ore deposit characterization campaigns or during the follow-up extraction operations where it is important to distinguish the main constituting Co-phase(s). The main advantage of this technique is its speed since no sample preparation is required during the collection Raman spectra that usually last few tens of seconds. The method provides information at a μm-scale and several points are thus required to fully characterize ore batches composed of different mineralogical phases. Our petrographical observations show also that asbolane and heterogenite mineralogical phases can coexist at a μm-scale as two distinct phases into 'heterogenite' ore. The distinction between heterogenite and asbolane from our sample set can also be conducted on a chemical base showing that heterogenite represents the richer Co-phase with variable Cu concentrations. By contrast, only Mn traces are usually observed in heterogenite minerals from DRC except in few samples, but always in lower concentration than in asbolane. The latter shows variable Mn/(Mn+Co) ratio between 0.85 and 0.3 and the decrease of this value is

  7. Quantifying cobalt in doping control urine samples--a pilot study.

    Science.gov (United States)

    Krug, Oliver; Kutscher, Daniel; Piper, Thomas; Geyer, Hans; Schänzer, Wilhelm; Thevis, Mario

    2014-01-01

    Since first reports on the impact of metals such as manganese and cobalt on erythropoiesis were published in the late 1920s, cobaltous chloride became a viable though not widespread means for the treatment of anaemic conditions. Today, its use is de facto eliminated from clinical practice; however, its (mis)use in human as well as animal sport as an erythropoiesis-stimulating agent has been discussed frequently. In order to assess possible analytical options and to provide relevant information on the prevalence of cobalt use/misuse among athletes, urinary cobalt concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS) from four groups of subjects. The cohorts consisted of (1) a reference population with specimens of 100 non-elite athletes (not being part of the doping control system), (2) a total of 96 doping control samples from endurance sport athletes, (3) elimination study urine samples collected from six individuals having ingested cobaltous chloride (500 µg/day) through dietary supplements, and (4) samples from people supplementing vitamin B12 (cobalamin) at 500 µg/day, accounting for approximately 22 µg of cobalt. The obtained results demonstrated that urinary cobalt concentrations of the reference population as well as the group of elite athletes were within normal ranges (0.1-2.2 ng/mL). A modest but significant difference between these two groups was observed (Wilcoxon rank sum test, p cobalt levels. The elimination study urine specimens yielded cobalt concentrations between 40 and 318 ng/mL during the first 6 h post-administration, and levels remained elevated (>22 ng/mL) up to 33 h. Oral supplementation of 500 µg of cobalamin did not result in urinary cobalt concentrations > 2 ng/mL. Based on these pilot study data it is concluded that measuring the urinary concentration of cobalt can provide information indicating the use of cobaltous chloride by athletes. Additional studies are however

  8. 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.

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

    Science.gov (United States)

    Prescott, E; Netterstrøm, B; Faber, J; Hegedüs, L; Suadicani, P; Christensen, J M

    1992-04-01

    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 versus 0.13 micrograms.mmol-1, P less than 0.0001). These subjects also had increased levels of serum thyroxine (T4) and free thyroxine (FT4I) (P = 0.0001 and 0.0029, respectively), unaltered serum thyroid stimulating hormone (TSH), and marginally reduced 3,5,3'-triiodothyronine (T3), whereas thyroid 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.

  10. A novel slurry sampling analysis of lead in different water samples by electrothermal atomic absorption spectrometry after coprecipitated with cobalt/pyrrolidine dithiocarbamate complex

    Energy Technology Data Exchange (ETDEWEB)

    Baysal, A. [Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, 34469 Maslak, Istanbul (Turkey); Akman, S. [Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, 34469 Maslak, Istanbul (Turkey)], E-mail: akmans@itu.edu.tr; Calisir, F. [Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, 34469 Maslak, Istanbul (Turkey)

    2008-10-30

    A preconcentration/separation technique based on the coprecipitation of lead with cobalt/pyrrolidine dithiocarbamate complex (Co(PDC){sub 2}) and subsequently its direct slurry sampling determination by electrothermal atomic absorption spectrometry (AAS) was described. For this purpose, at first, lead was coprecipitated with cobalt/pyrrolidine dithiocarbamate complex formed using ammonium pyrrolidine dithiocarbamate (APDC) as a chelating agent and cobalt as a carrier element. The supernatant was then separated and the slurry of the precipitate prepared in Triton X-100 was directly analyzed by electrothermal atomic absorption spectrometry with respect to lead concentration. The effects of experimental conditions on coprecipitation of lead with gathering precipitate as well as homogeneity and stability of the slurry were investigated. After the optimization of experimental parameters, a 100-fold enrichment of the analyte with quantitative recovery (>90%) and high precision (<10% R.S.D.) were obtained. By using the proposed technique, the lead concentrations in heavy matrices of Certified Sea-water and wastewater samples could be practically and rapidly determined in the range of 95% confidence level. The detection limit of the described method for lead using sample-matching blanks was 1.5 ng/L (3{sigma}, N = 10)

  11. Cloud Point Extraction for the Determination of Trace Amounts of Cobalt in Water and Food Samples by Flame Atomic Absorption Spectrometry

    Directory of Open Access Journals (Sweden)

    Shangzhi Wang

    2013-01-01

    Full Text Available A cloud point extraction (CPE procedure which was developed for the separation and preconcentration of trace amounts of cobalt is combined with flame atomic absorption spectrometry (FAAS to determine trace amounts of cobalt in water and food samples. The procedure is based on the formation of the hydrophobic complex between Co(II and 4-methoxy-2-sulfo-benzenediazoaminoazo-benzene (MOSDAA followed by its extraction into a Triton X-114 surfactant-rich phase. The parameters such as pH of sample, concentrations of MOSDAA and Triton X-114, equilibrium temperature, and equilibrium time, which affect both complexation and extraction, are optimized. Under the selected optimum conditions, the preconcentration of 10.0 mL, 0.1 μg mL−1 Co(II solution results in a limit of detection of 0.47 ng mL−1 (3σ and an enrichment factor of 19. A relative standard deviation of 2.78% (,  μg mL−1 for the determination of Co(II is obtained. The proposed method was applied for the determination of trace amounts of cobalt in river water and millet samples with satisfactory results.

  12. HEAVY METALS ABUNDANCE IN THE SOILS OF THE PANTELIMON – BRĂNEŞTI AREA, ILFOV COUNTY a CADMIUM, COBALT, CHROMIUM, COPPER

    Directory of Open Access Journals (Sweden)

    Radu Lacatusu

    2011-12-01

    Full Text Available More than 20 years later, a new research on heavy metals (cadmium, cobalt, chromium, copper contents in the soil cover of the Pantelimon – Brăneşti area located East of the Bucharest Municipality and exposed for several decades to the influence of industrial emissions from two non-ferrous metallurgy plants is presented. A 5,912.72 ha area was investigated, 544 samples taken by geometric horizons (0-20; 20-40; 40-60 cm from 215 points have been analyzed.The dominant soils are: Preluvosols, Chernozems, Phaeozems. The analytical data showed that all the heavy metals contents are below the maximum allowable limits and of the alarm thresholds. Higher cadmium and copper concentrations have been registered in the 40-60 cm layer and higher chromium and copper concentrations in the 0-20 cm layer. Cadmium and cobalt distributions are non-central, with a right asymmetry, and the chromium and copper ones are slightly symmetric. The surface distribution of the heavy metals shows the presence of some high contents areas distributed insularly, with a higher frequency around the industrial units. The geochemical abundance indexes are higher than 1 for cadmium and lower for cobalt, chromium, and copper, and the pedo-geochemical abundance indexes are lower than 1 only for chromium.

  13. Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Paula [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN - CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Wuilloud, Rodolfo G., E-mail: rwuilloud@mendoza-conicet.gov.ar [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN - CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina)

    2010-03-10

    A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C{sub 6}mim][PF{sub 6}] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L{sup -1}, while the relative standard deviation (RSD) was 3.4% (at 1 {mu}g L{sup -1} Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

  14. Quantification of Trace Amounts of Impurities in High Purity Cobalt by High Resolution Inductively Coupled Plasma Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    Hua Lin XIE; Xi Du NIE; You Gen TANG

    2006-01-01

    An analytical method using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of Be, Mg, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn, Sb, Ba, Pt, Au and Pb in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCl. The matrix effects due to thc presence of excess HCl and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination was tested and discussed. Correction for matrix effects, Sc, Rh and Bi were used as internal standards. The detection limits is 0.003-0.57 μg/g, the recovery ratio is 92.2%- 111.2%, and the RSD is less than 3.6%. The method is accurate, quick and convenient. It has been applied to the determination of trace impurities in high purity cobalt with satisfactory results.

  15. Quantification of trace amounts of impurities in high purity cobalt by high resolution inductively coupled plasma mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    XIE Hualin; HUANG Kelong; NIE Xidu; TANG Yougen

    2007-01-01

    An analytical method using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of 24 elements (Be, Mg, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn,Sb, Ba, Pt, Au, and Pb) in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCl. The matrix effects because of the presence of excess HCl and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits were 0.016-1.50 μg.g-1, the recovery ratios were 92.2%-111.2%, and the RSD was less than 3.6%. The method was accurate, quick, and convenient. It was applied to the determination of trace impurities in high purity cobalt with satisfactory results.

  16. Preconcentration and separation of nickel, copper and cobalt using solid phase extraction and their determination in some real samples.

    Science.gov (United States)

    Ghaedi, M; Ahmadi, F; Soylak, M

    2007-08-17

    A solid phase extraction method has been developed to separate and concentrate trace amounts of nickel, cobalt and copper ions from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through activated carbon modified by dithioxamide (rubeanic acid) (DTO), Ni2+, Cu2+ and Co2+ ions adsorb quantitatively. The recoveries of analytes at pH 5.5 with 500 mg solid phase were greater than 95% without interference from alkaline, earth alkaline and some metal ions. The enrichment factor was 330. The detection limits by three sigma were 0.50 microg L(-1) for copper, 0.75 microg L(-1) for nickel and 0.80 microg L(-1) for cobalt. The loading capacity was 0.56 mg g(-1) for Ni2+, 0.50 mg g(-1) for Cu2+ and 0.47 mg g(-1) for Co2+. The presented procedure was applied to the determination of analytes in tap, river and sea waters, vegetable, soil and blood samples with successfully results (recoveries greater than 95%, R.S.D. lower than 2% for n=3).

  17. Limits on $\

    CERN Document Server

    Perego, D L

    2002-01-01

    A limit on the tau neutrino mass is obtained using all the $Z^{0} \\to \\tau^{+} \\tau^{-}$ data collected at LEP by the DELPHI detector between 1992 and 1995. In this analysis events in which one of the taus decays into one charged particle, while the second $\\tau$ decays into f{}ive charged pions (1-5 topology) have been used. The neutrino mass is determined from a bidimensional \\fit ~on the invariant mass $m^{*}_{5 \\pi}$ and on the energy $E_{5 \\pi}$ of the f{}ive $\\pi^{\\pm}$ system. The result found is $m_{\

  18. 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.

  19. Cobalt nano-particles for application in magnetic data storage

    CERN Document Server

    Holmes, B M

    2002-01-01

    Particulate magnetic media has been produced through a novel technique, whereby the rapid thermal decomposition of reactively sputtered pre-cursor thin films of cobalt nitride results in a two dimensional array of hcp cobalt particles. The samples produced have been examined and characterised, magnetically, optically, and magneto-optically with respect to the thickness of the precursor films of CoN. Samples with a volume thickness of less than 20A have been found to fall within the superparamagnetic size range, whilst samples thicker than this are found to consist of single domain ferromagnetic particles. The media displays magnetic properties that are greatly enhanced compared to those of bulk Co. The diameters of the particles have been found to be approximately equal to the optimum size range required for high-density magnetic storage. An analysis of the magnetic properties of a core set of samples has enabled a value to be obtained for both the thickness of the oxide shell as well as the effective anisotr...

  20. Development of a transferable reactive force field for cobalt.

    Science.gov (United States)

    Labrosse, Matthew R; Johnson, J Karl; van Duin, Adri C T

    2010-05-13

    ReaxFF provides a method to describe bond-breaking and bond-forming events that can be applied to large-scale molecular dynamics simulations. This article describes the development of a ReaxFF potential for cobalt. This potential is transferable to a wide variety of cobalt systems, including various crystal structures, surfaces, clusters, and defects. The potential parameters were obtained from an extensive set of ab initio calculations. We have tested these parameters against additional DFT calculations not included in the fitting data set and found that ReaxFF provides similar or superior agreement with the DFT results compared to accepted embedded atom method descriptions for Co. We validated this potential by performing large-scale molecular dynamics simulations to predict the melting point, diffusion coefficients for the liquid as a function of temperature, and vacancy-mediated diffusion coefficients in the solid as a function of temperature and vacancy concentration. Results are compared with other theoretical methods and experiments where available. Since the ReaxFF method allows straightforward extensions to alloys and heterogeneous materials, including first-row elements, the ReaxFF parameters described here provide a foundation for the simulation of a wide range of Co-containing materials.

  1. 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.

  2. Sonochemical synthesis of cobalt aluminate nanoparticles under various preparation parameters.

    Science.gov (United States)

    Lv, Weizhong; Qiu, Qi; Wang, Fang; Wei, Shaohui; Liu, Bo; Luo, Zhongkuan

    2010-06-01

    Cobalt aluminate (CoAl(2)O(4)) nanoparticles were synthesized using a precursor method with the aid of ultrasound irradiation under various preparation parameters. The effects of the preparation parameters, such as the sonochemical reaction time and temperature, precipitation agents, calcination temperature and time on the formation of CoAl(2)O(4) were investigated. The precursor on heating yields nanosized CoAl(2)O(4) particles and both these nanoparticles and the precursor were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The use of ultrasound irradiation during the homogeneous precipitation of the precursor reduces the duration of the precipitation reaction. The mechanism of the formation of cobalt aluminate was investigated by means of Fourier transformation infrared spectroscopy (FT-IR) and EDX (energy dispersive X-ray). The thermal decomposition process and kinetics of the precursor of nanosized CoAl(2)O(4) were investigated by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). The apparent activation energy (E) and the pre-exponential constant (A) were 304.26 kJ/mol and 6.441 x 10(14)s(-1), respectively. Specific surface area was investigated by means of Brunauer Emmett Teller (BET) surface area measurements.

  3. Braze welding of cobalt with a silver–copper filler

    Directory of Open Access Journals (Sweden)

    Everett M. Criss

    2015-01-01

    Full Text Available A new method of joining cobalt by braze-welding it with a silver–copper filler was developed in order to better understand the residual stresses in beryllium–aluminum/silicon weldments which are problematic to investigate because of the high toxicity of Be. The base and filler metals of this new welding system were selected to replicate the physical properties, crystal structures, and chemical behavior of the Be–AlSi welds. Welding parameters of this surrogate Co–AgCu system were determined by experimentation combining 4-point bending tests and microscopy. Final welds are 5 pass manual TIG (tungsten inert gas, with He top gas and Ar back gas. Control of the welding process produces welds with full penetration melting of the cobalt base. Microscopy indicates that cracking is minimal, and not through thickness, whereas 4-point bending shows failure is not by base-filler delamination. These welds improve upon the original Be–AlSi welds, which do not possess full penetration, and have considerable porosity. We propose that utilization of our welding methods will increase the strength of the Be–AlSi weldments. The specialized welding techniques developed for this study may be applicable not only for the parent Be–AlSi welds, but to braze welds and welds utilizing brittle materials in general. This concept of surrogacy may prove useful in the study of many different types of exotic welds.

  4. Impact of wastewater reuse on cobalt status in Egyptian environment

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    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 and El-Suez 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.

  5. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses

    Directory of Open Access Journals (Sweden)

    Annalena Wolff

    2014-02-01

    Full Text Available Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment.

  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. Monodisperse cobalt ferrite nanomagnets with uniform silica coatings.

    Science.gov (United States)

    Dai, Qiu; Lam, Michelle; Swanson, Sally; Yu, Rui-Hui Rachel; Milliron, Delia J; Topuria, Teya; Jubert, Pierre-Olivier; Nelson, Alshakim

    2010-11-16

    Ferro- and ferrimagnetic nanoparticles are difficult to manipulate in solution as a consequence of the formation of magnetically induced nanoparticle aggregates, which hamper the utility of these particles for applications ranging from data storage to bionanotechnology. Nonmagnetic shells that encapsulate these magnetic particles can reduce the interparticle magnetic interactions and improve the dispersibility of the nanoparticles in solution. A route to create uniform silica shells around individual cobalt ferrite nanoparticles--which uses poly(acrylic acid) to bind to the nanoparticle surface and inhibit nanoparticle aggregation prior to the addition of a silica precursor--was developed. In the absence of the poly(acrylic acid) the cobalt ferrite nanoparticles irreversibly aggregated during the silica shell formation. The thickness of the silica shell around the core-shell nanoparticles could be controlled in order to tune the interparticle magnetic coupling as well as inhibit magnetically induced nanoparticle aggregation. These ferrimagnetic core-silica shell structures form stable dispersion in polar solvents such as EtOH and water, which is critical for enabling technologies that require the assembly or derivatization of ferrimagnetic particles in solution.

  8. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses.

    Science.gov (United States)

    Wolff, Annalena; Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment.

  9. 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.

  10. 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.

  11. Oxygen evolution reaction on cobalt. Pt. 2. Transient measurements

    Energy Technology Data Exchange (ETDEWEB)

    Willems, H.; Kobussen, A.G.C.; Vinke, I.C.; Wit, J.H.W. de; Broers, G.H.J.

    1985-10-25

    Open-circuit overpotential decays on an aged cobalt electrode in the oxygen evolution range in 6 M KOH show different slopes for two overpotential regions. These slopes are lower than the Tafel slope in the same region: Tafel slopes of proportional100 and proportional40 mV/dec, at high and low overpotentials, respectively, compared to decay slopes of proportional -60 and proportional -20 to -30 mV/dec. For a fresh cobalt electrode a decay slope of proportional -40 mV/dec is found at high overpotentials. From impedance measurements during a decay it is concluded that the electrode capacitance cannot account for the decay curves observed. By means of steady-state potentiostatic impedance measurements (with stabilization times >24 h) it is found that the differential Tafel slope remains constant at proportional40-50 mV/dec and differs considerably from the Tafel slope at high overpotentials, proportional100 mV/dec. Galvanostatic pulse experiments give evidence of the presence of CoO/sub 2/ in the oxide layer. Two models which may explain the observed experimental results are analysed. Both include a potential-dependent (extra) process which is fixed by the amount of CoO/sub 2/ at the surface. In one model, CoO/sub 2/ is responsible for partial surface blockage (parallel process); in the other model, CoO/sub 2/ controls the conductivity of the top layer of the oxide layer on the electrode. (orig.).

  12. 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.

  13. Antibacterial Activity of Copper and Cobalt Amino Acids Complexes

    Directory of Open Access Journals (Sweden)

    ANDREEA STĂNILĂ

    2011-11-01

    Full Text Available The antibacterial properties of differently copper and cobalt amino acids complexes on agar plates was investigated in the present study. The antibacterial activity of amino acid complexes was evaluated against on three bacteria strains (Escherichia coli, Bacillus cereus, Micrococcus luteus. Generally, the amino acids complexes were mainly active against gram-positive organisms, species like Micrococcus luteus being the most susceptible strain tested. It was registered a moderate antibacterial activity against Bacillus cereus. The microorganisms Escherichia coli, which are already known to be multi-resistant to drugs, were also resistant to the amino acids complexes but also to the free salts tested. Escherichia coli were susceptible only to the CoCl2 and copper complex with phenylalanine. The complexes with leucine and histidine seem to be more active than the parent free ligand against one or more bacterial species. Moderate activity was registered in the case of complexes with methionine and phenylalanine. From the complexes tested less efficient antibacterial activity was noted in the case of complexes with lysine and valine. These results show that cobalt and copper complexes have an antibacterial activity and suggest their potential application as antibacterial agents.

  14. Dimensional control of cobalt spin state in oxide superlattices

    Science.gov (United States)

    Jeong, Da Woon; Choi, W. S.; Okamoto, S.; Sohn, C. H.; Park, H. J.; Kim, J.-Y.; Lee, H. N.; Kim, K. W.; Moon, S. J.; Noh, T. W.

    2013-03-01

    Perovskite cobalt oxide is a very intriguing system with various spin states owing to the delicate balance between crystal field splitting and Hund exchange energy. In this talk, we show that its spin state can be altered through dimensional control, enabled by digital synthesis of perovskite cobalt oxide superlattices. We employed a few unit cells of LaCoO3 as an active magnetic layer, separated by LaAlO3 spacer layer. High quality [(LaCoO3) n (LaAlO3) n ]8 (n = 2, 6, and 10) superlattices were fabricated using pulsed laser epitaxy. Spectroscopic tools including x-ray absorption spectroscopy and optical spectroscopy revealed clear evolution of the electronic structure and resultant spin state by changing dimensionality. Specifically, the spin state changed from a high to a low spin state with a larger optical band gap, as the dimension reduced from 3D to 2D. Dynamic mean field calculation supported the critical role of dimensionality on the spin state and electronic structure of LaCoO3.

  15. Cobalt silicate hierarchical hollow spheres for lithium-ion batteries

    Science.gov (United States)

    Yang, Jun; Guo, Yuanyuan; Zhang, Yufei; Sun, Chencheng; Yan, Qingyu; Dong, Xiaochen

    2016-09-01

    In this paper, the synthesis of cobalt silicate novel hierarchical hollow spheres via a facile hydrothermal method is presented. With a unique hollow structure, the Co2SiO4 provides a large surface area, which can shorten the lithium ions diffusion length and effectively accommodate the volumetic variation during the lithiation/de-lithiation process. Serving as an anode material in lithium-ion battery application, the Co2SiO4 electrode demonstrates a high reversible specific capacity (first-cycle charge capacity of 948.6 mAh g-1 at 100 mA g-1), a cycling durability (specific capacity of 791.4 mAh g-1 after 100 cycles at 100 mA g-1), and a good rate capability (specific capacity of 349.4 mAh g-1 at 10 A g-1). The results indicate that the cobalt silicate hierarchical hollow sphere holds the potential applications in energy storage electrodes.

  16. Development and characterization of cobalt based nanostructured super hydrophobic coating

    Science.gov (United States)

    Mohsin, H.; Sultan, U.; Joya, Y. F.; Ahmed, S.; Awan, M. S.; Arshad, S. N.

    2016-08-01

    A super hydrophobic coating on the surface of glass substrate has been developed using chemical bath deposition (CBD) process. A water contact angle (WCA) greater than 150° has been achieved. Cobalt Chloride (CoCl2) has been used as the main precursor to investigate optimum composition and high superhydrophobicity. The water droplet has been observed to slide with a sliding angle less than ∼⃒3°. This effect is particularly due to the surface morphology (roughness) and low surface energy that causes water droplet to form a large contact angle thus allowing the surface to show water-repellent properties. Deposition time is the primary parameter affecting the coating properties and a different WCA value has been observed by increasing time. Scanning Electron Microscopy (FE-SEM) images show the presence of a nano flower-like morphology that helps in imparting superhydrophobic behavior. Energy Dispersive X-ray Spectroscopy (EDX) indicate the coating to be composed of cobalt as the main constituent. Contact Angle Measurement confirms the contact angle value to be greater than 170°.

  17. Results of experimental investigations of cobalt beta decay rate variation

    CERN Document Server

    Baurov, Yu A; Nikitin, V A; Dunin, V B; Tihomirov, V V; Sergeev, S V; Demchuk, N A

    2013-01-01

    Results of long-term investigations of variation of cobalt beta decay rate from 28.12.2010 till 08.02.2012 are presented. The scintillation spectrometer with two LaBr3 detectors is used to register of gamma-quanta with energy 1.173 and 1.332 MeV accompanying cobalt beta decay. Counting rate of each detector and their gamma-quanta coincidence are collected in successive time intervals 10 s. The statistical Kolmogorov-Smirnov method for data analysis is used. Temperature influence on experimental results is also analyzed. Deviations of beta decay counting rate from constant distribution during the days were detected in those decades: from 11.03 to 21.03 with significance level a = 0.1; from 22.04 to 02.05 with a=0.0125; from 24.06 to 04.07 with a=0.05; from 04.08 to 14.08 with a=0.05.

  18. Enhanced peroxidase activity and tumour tissue visualization by cobalt-doped magnetoferritin nanoparticles

    Science.gov (United States)

    Zhang, Tongwei; Cao, Changqian; Tang, Xu; Cai, Yao; Yang, Caiyun; Pan, Yongxin

    2017-01-01

    Magnetoferritin (M-HFn) is a biomimetic magnetic nanoparticle with a human heavy-chain ferritin (HFn) shell, trapping a magnetite (Fe3O4) core that has inherited peroxidase-like activity. In this study, cobalt-doped M-HFn nanoparticles (M-HFn-Co x Fe3-x O4) with different amounts of cobalt were successfully synthesized. Experimental results indicate that the controlled doping of a certain amount of cobalt into the magnetite cores of M-HFn nanoparticles enhances its peroxidase-like catalytic activity and efficacy for visualizing tumour tissues. For example, compared with sample Co0 (without cobalt doping), the peroxidase-like activity of the cobalt-doped nanoparticle sample Co60 (with a cobalt doping molar percentage of ˜34.2%) increases 1.7 times, and has the maximal reaction velocity (V max) values. Moreover, after a one-step incubation with Co60 nanoparticles, and using the peroxidase substrate 3,3‧-diaminobenzidine tetrahydrochloride (DAB) for colour development, the tumour tissues of breast, colorectal, stomach and pancreas tumours showed a deeper brown colour with clear boundaries between the healthy and tumourous cells. Therefore, this suggests that the cobalt-doped magnetoferritin nanoparticles enhance peroxidase activity and tumour tissue visualization.

  19. 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

  20. Direct Electrochemical Preparation of Cobalt, Tungsten, and Tungsten Carbide from Cemented Carbide Scrap

    Science.gov (United States)

    Xiao, Xiangjun; Xi, Xiaoli; Nie, Zuoren; Zhang, Liwen; Ma, Liwen

    2017-02-01

    A novel process of preparing cobalt, tungsten, and tungsten carbide powders from cemented carbide scrap by molten salt electrolysis has been investigated in this paper. In this experiment, WC-6Co and NaCl-KCl salt were used as sacrificial anode and electrolyte, respectively. The dissolution potential of cobalt and WC was determined by linear sweep voltammetry to be 0 and 0.6 V ( vs Ag/AgCl), respectively. Furthermore, the electrochemical behavior of cobalt and tungsten ions was investigated by a variety of electrochemical techniques. Results of cyclic voltammetry (CV) and square-wave voltammetry show that the cobalt and tungsten ions existed as Co2+ and W2+ on melts, respectively. The effect of applied voltage, electrolysis current, and electrolysis times on the composition of the product was studied. Results showed that pure cobalt powder can be obtained when the electrolysis potential is lower than 0.6 V or during low current and short times. Double-cathode and two-stage electrolysis was utilized for the preparation of cobalt, tungsten carbide, and tungsten powders. Additionally, X-ray diffraction results confirm that the product collected at cathodes 1 and 2 is pure Co and WC, respectively. Pure tungsten powder was obtained after electrolysis of the second part. Scanning electron microscope results show that the diameters of tungsten, tungsten carbide, and cobalt powder are smaller than 100, 200, and 200 nm, respectively.

  1. Magnetic Properties of Cobalt-coated Silicon Steels Prepared by Electrodeposition

    Directory of Open Access Journals (Sweden)

    Somkane PIROMRAK

    2007-01-01

    Full Text Available Magnetic properties of silicon steels (1.26 % silicon coated by cobalt of varying thickness were studied. Cobalt ranging from 11 to 68 µm in thickness was deposited on silicon steel substrates (0.5 mm thick, 0.4 mm wide and 55.0 mm long cut from sheets of recycled transformer cores. By electrodeposition in CoSO4 electrolyte with 90 mA applied current at pH 1.86, the deposition rate was 1.11 µm/min. Although deposition of cobalt increased saturation induction of silicon steels, it also increased hysteresis loss signified by wider hysteresis loops with larger remanent induction and coercive field. Since the magnetoimpedance (MI is related to the magnetic softness of materials, the MI ratio decreased with increasing thickness of the cobalt layer. Although the cobalt coating did not enhance the MI ratio of silicon steels, it expanded the peak of frequency-dependent MI curves. Therefore, the frequency range with large MI ratio in silicon steels can be extended by the deposition of a cobalt layer. From microscopic images, grains and magnetic domains of the silicon steel were of the order of 10 µm whereas smaller domain size was observed in the cobalt layer.

  2. Cobalt and nickel stabilize stem cell transcription factor OCT4 through modulating its sumoylation and ubiquitination.

    Directory of Open Access Journals (Sweden)

    Yixin Yao

    Full Text Available Stem cell research can lead to the development of treatments for a wide range of ailments including diabetes, heart disease, aging, neurodegenerative diseases, spinal cord injury, and cancer. OCT4 is a master regulator of self-renewal of undifferentiated embryonic stem cells. OCT4 also plays a crucial role in reprogramming of somatic cells into induced pluripotent stem (iPS cells. Given known vivo reproductive toxicity of cobalt and nickel metals, we examined the effect of these metals on expression of several stem cell factors in embryonic Tera-1 cells, as well as stem cells. Cobalt and nickel induced a concentration-dependent increase of OCT4 and HIF-1α, but not NANOG or KLF4. OCT4 induced by cobalt and nickel was due primarily to protein stabilization because MG132 stabilized OCT4 in cells treated with either metals and because neither nickel nor cobalt significantly modulated its steady-state mRNA level. OCT4 stabilization by cobalt and nickel was mediated largely through reactive oxygen species (ROS as co-treatment with ascorbic acid abolished OCT4 increase. Moreover, nickel and cobalt treatment increased sumoylation and mono-ubiquitination of OCT4 and K123 was crucial for mediating these modifications. Combined, our observations suggest that nickel and cobalt may exert their reproductive toxicity through perturbing OCT4 activity in the stem cell compartment.

  3. Direct Electrochemical Preparation of Cobalt, Tungsten, and Tungsten Carbide from Cemented Carbide Scrap

    Science.gov (United States)

    Xiao, Xiangjun; Xi, Xiaoli; Nie, Zuoren; Zhang, Liwen; Ma, Liwen

    2016-10-01

    A novel process of preparing cobalt, tungsten, and tungsten carbide powders from cemented carbide scrap by molten salt electrolysis has been investigated in this paper. In this experiment, WC-6Co and NaCl-KCl salt were used as sacrificial anode and electrolyte, respectively. The dissolution potential of cobalt and WC was determined by linear sweep voltammetry to be 0 and 0.6 V (vs Ag/AgCl), respectively. Furthermore, the electrochemical behavior of cobalt and tungsten ions was investigated by a variety of electrochemical techniques. Results of cyclic voltammetry (CV) and square-wave voltammetry show that the cobalt and tungsten ions existed as Co2+ and W2+ on melts, respectively. The effect of applied voltage, electrolysis current, and electrolysis times on the composition of the product was studied. Results showed that pure cobalt powder can be obtained when the electrolysis potential is lower than 0.6 V or during low current and short times. Double-cathode and two-stage electrolysis was utilized for the preparation of cobalt, tungsten carbide, and tungsten powders. Additionally, X-ray diffraction results confirm that the product collected at cathodes 1 and 2 is pure Co and WC, respectively. Pure tungsten powder was obtained after electrolysis of the second part. Scanning electron microscope results show that the diameters of tungsten, tungsten carbide, and cobalt powder are smaller than 100, 200, and 200 nm, respectively.

  4. 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.

  5. Tunable magnetocrystalline easy axis in cobalt nanowire arrays by zinc additive

    Energy Technology Data Exchange (ETDEWEB)

    Manouchehri, A. [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Ramazani, A., E-mail: rmzn@kashanu.ac.ir [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Department of Physics, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Kashi, M. Almasi [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Department of Physics, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Montazer, A.H. [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of)

    2016-05-15

    Graphical abstract: - Highlights: • Pure Co and Co-rich CoZn NW arrays were fabricated into AAO templates. • Effect of Zn additive on magnetic properties and crystal structure was investigated. • Coercivity and squareness of Co NWs increased up to 2150 Oe and 0.93 by Zn additive. • Incorporation of Zn rotated Co c-axis from perpendicular to parallel to NW axis. - Abstract: A new approach to tuning the crystalline characteristics and magnetic properties of cobalt nanowire (NW) arrays embedded in AAO templates is reported using zinc additive. This is realized by adding low concentrations of Zn when pulse-electrodepositing cobalt NWs while also increasing the solution pH from 3 to 5. Using hysteresis loop measurements with a magnetic field applied parallel to the NW axis, coercivity and squareness of pure cobalt NWs increased from 890 Oe and 0.45 to 2150 Oe and 0.93 in Co{sub 97}Zn{sub 3} NWs, respectively, using a Zn concentration of 0.01 M at pH = 4. XRD patterns obtained from the cobalt-rich CoZn NWs revealed that the crystalline texture of cobalt changes from [1 0 0] direction to [1 0 1] and [0 0 2] at pH = 3 and 4, respectively. For the latter, the magnetocrystalline easy axis of cobalt rotates from nearly perpendicular to parallel to the NW axis, induced by the incorporation of zinc into the hcp structure of cobalt.

  6. Dose-dependent cytotoxicity of clinically relevant cobalt nanoparticles and ions on macrophages in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young-Min; Xia Zhidao; Glyn-Jones, Sion; Beard, David; Gill, Harinderjit S; Murray, David W, E-mail: young-min.kwon@ndos.ox.ac.u [Nuffield Department of Orthopaedic Surgery, University of Oxford, Oxford OX3 7LD (United Kingdom)

    2009-04-15

    Despite the satisfactory short-term implant survivorship of metal-on-metal hip resurfacing arthroplasty, periprosthetic soft-tissue masses such as pseudotumours are being increasingly reported. Cytotoxic effects of cobalt or chromium have been suggested to play a role in its aetiology. The aim of this study was to investigate the effects of clinically relevant metal nanoparticles and ions on the viability of macrophages in vitro. A RAW 264.7 murine macrophage cell line was cultured in the presence of either: (1) cobalt, chromium and titanium nanoparticles sized 30-35 nm; or (2) cobalt sulphate and chromium chloride. Two methods were used to quantify cell viability: Alamar Blue assay and Live/Dead assay. The cytotoxicity was observed only with cobalt. Cobalt nanoparticles and ions demonstrated dose-dependent cytotoxic effects on macrophages in vitro: the cytotoxic concentrations of nanoparticles and ions were 1 x 10{sup 12} particles ml{sup -1} and 1000 {mu}M, respectively. The high concentration of cobalt nanoparticles required for cytotoxicity of macrophages in vitro suggests that increased production of cobalt nanoparticles in vivo, due to excessive MoM implant wear, may lead to local adverse biological effects. Therefore, cytotoxicity of high concentrations of metal nanoparticles phagocytosed by macrophages located in the periprosthetic tissues may be an important factor in pathogenesis of pseudotumours.

  7. Effects of cobalt chloride on nitric oxide and cytokines/chemokines production in microglia.

    Science.gov (United States)

    Mou, Yan Hua; Yang, Jing Yu; Cui, Nan; Wang, Ji Ming; Hou, Yue; Song, Shuang; Wu, Chun Fu

    2012-05-01

    The involvement of microglial activation in metal neurotoxicity is becoming increasingly recognized. Some metal ions, such as zinc (II) and manganese (II), have been recently reported as microglial activators to induce the release of inflammatory mediators including cytokines, chemokines and nitric oxide (NO) which are involved in the pathogenesis of neurological diseases. Cobalt is essential for human life. However, excessive cobalt is cytotoxic and neurotoxic. In the present study, we determined cobalt-induced production of NO and cytokines/chemokines in N9 cells, a murine microglial cell line. High levels of cobalt significantly up-regulated iNOS mRNA and protein expression, which resulted in the release of NO. Cobalt induced the production of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) in a concentration- and time-dependent manner in both N9 cells and primary mouse microglia and increased lipopolysaccharides (LPS)-induced cytokine production. Further study showed that cobalt induced cytokine production by a mechanism involving both nuclear factor kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signaling pathways. The involvement of reactive oxygen species (ROS) in microglial activation was also confirmed. These findings suggested that cobalt neurotoxicity should be attributed not only directly to neuronal damage but also indirectly to microglial activation which might potentiate neuronal injury via elevation of proinflammatory mediator levels.

  8. Mobile Phones: Potential Sources of Nickel and Cobalt Exposure for Metal Allergic Patients.

    Science.gov (United States)

    Aquino, Marcella; Mucci, Tania; Chong, Melanie; Lorton, Mark Davis; Fonacier, Luz

    2013-12-01

    The use of cellular phones has risen exponentially with over 300 million subscribers. Nickel has been detected in cell phones and reports of contact dermatitis attributable to metals are present in the literature. We determined nickel and cobalt content in popular cell phones in the United States. Adults (>18 years) who owned a flip phone, Blackberry(®), or iPhone(®) were eligible. Seventy-two cell phones were tested using SmartPractice's(®) commercially available nickel and cobalt spot tests. Test areas included buttons, keypad, speakers, camera, and metal panels. Of the 72 cell phones tested, no iPhones or Droids(®) tested positive for nickel or cobalt. About 29.4% of Blackberrys [95% confidence interval (CI), 13%-53%] tested positive for nickel; none were positive for cobalt. About 90.5% of flip phones (95% CI, 70%-99%) tested positive for nickel and 52.4% of flip phones (95% CI, 32%-72%) tested positive for cobalt. Our study indicates that nickel and cobalt are present in popular cell phones. Patients with known nickel or cobalt allergy may consider their cellular phones as a potential source of exposure. Further studies are needed to examine whether there is a direct association with metal content in cell phones and the manifestation of metal allergy.

  9. 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.

  10. Cobalt and Nickel Stabilize Stem Cell Transcription Factor OCT4 through Modulating Its Sumoylation and Ubiquitination

    Science.gov (United States)

    Yao, Yixin; Lu, Yinghua; Chen, Wen-chi; Jiang, Yongping; Cheng, Tao; Ma, Yupo; Lu, Lou; Dai, Wei

    2014-01-01

    Stem cell research can lead to the development of treatments for a wide range of ailments including diabetes, heart disease, aging, neurodegenerative diseases, spinal cord injury, and cancer. OCT4 is a master regulator of self-renewal of undifferentiated embryonic stem cells. OCT4 also plays a crucial role in reprogramming of somatic cells into induced pluripotent stem (iPS) cells. Given known vivo reproductive toxicity of cobalt and nickel metals, we examined the effect of these metals on expression of several stem cell factors in embryonic Tera-1 cells, as well as stem cells. Cobalt and nickel induced a concentration-dependent increase of OCT4 and HIF-1α, but not NANOG or KLF4. OCT4 induced by cobalt and nickel was due primarily to protein stabilization because MG132 stabilized OCT4 in cells treated with either metals and because neither nickel nor cobalt significantly modulated its steady-state mRNA level. OCT4 stabilization by cobalt and nickel was mediated largely through reactive oxygen species (ROS) as co-treatment with ascorbic acid abolished OCT4 increase. Moreover, nickel and cobalt treatment increased sumoylation and mono-ubiquitination of OCT4 and K123 was crucial for mediating these modifications. Combined, our observations suggest that nickel and cobalt may exert their reproductive toxicity through perturbing OCT4 activity in the stem cell compartment. PMID:24497960

  11. 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

  12. Viability of an isocentric cobalt-60 teletherapy unit for stereotactic radiosurgery.

    Science.gov (United States)

    Poffenbarger, B A; Podgorsak, E B

    1998-10-01

    The potential for radiosurgery with an isocentric teletherapy cobalt unit was evaluated in three areas: (1) the physical properties of radiosurgical beams, (2) the quality of radiosurgical dose distributions obtained with four to ten noncoplanar converging arcs, and (3) the accuracy with which the radiosurgical dose can be delivered. In each of these areas the cobalt unit provides a viable alternative to an isocentric linear accelerator (linac) as a radiation source for radiosurgery. A 10 MV x-ray beam from a linac used for radiosurgery served as a standard for comparison. The difference between the 80%-20% penumbras of stationary radiosurgical fields in the nominal diameter range from 10 to 40 mm of the cobalt-60 and 10 MV photon beams is remarkably small, with the cobalt-60 beam penumbras, on average, only about 0.7 mm larger than those of the linac beam. Differences between the cobalt-60 and 10 MV radiosurgical treatment plans in terms of dose homogeneity within the target volume, conformity of the prescribed isodose volume to the target volume, and dose falloffs outside the target volume are also minimal, and therefore of essentially no clinical significance. Moreover, measured isodose distributions for a radiosurgical procedure on our Theratron T-780 cobalt unit agreed with calculated distributions to within the +/- 1 mm spatial and +/- 5% numerical dose tolerances, which are generally specified for radiosurgery. The viability of isocentric cobalt units for radiosurgery will be of particular interest to centers in developing countries where cobalt units, because of their relatively low costs, provide the only megavoltage source of radiation for radiotherapy, and could easily and inexpensively be modified for radiosurgery. Of course, the quality assurance protocols and mechanical condition of a particular teletherapy cobalt unit must meet stringent requirements before the use of the unit for radiosurgery can be advocated.

  13. 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

  14. Edge reactivity and water-assisted dissociation on cobalt oxide nanoislands

    DEFF Research Database (Denmark)

    Fester, J.; García-Melchor, M.; Walton, A. S.

    2017-01-01

    . Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy and computational modelling, how hydroxyls form from water dissociation at under coordinated cobalt edge sites of cobalt oxide nanoislands. Surprisingly, we find that an additional water molecule acts to promote all...... the elementary steps of the dissociation process and subsequent hydrogen migration, revealing the important assisting role of a water molecule in its own dissociation process on a metal oxide. Inspired by the experimental findings, we theoretically model the oxygen evolution reaction activity of cobalt oxide...

  15. SYNTHETIC AND CATALYTIC PROPERTY STUDIES ON SILICA SUPPORTED BIS-(ACETYLACETONATO ) COBALT(Ⅱ) COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    LI Xiaohu; LU Yun; LIN Sicong

    1992-01-01

    This paper reports mainly the preparation of silica supported acetylacetone ligands and their cobalt complexes, the characterization of their chemical structure, and the evaluation of their catalytic activity in the reaction for the preparation of ethers directly from alkanols and benzyl chloride. The results indicate that those silica supported β-diketone cobalt complexes (SACO) not only can simplify the reaction procedure of the ether preparation but also show a much higher catalytic activity in comparison with other homogeneous catalysts. In addition, SACO can be recovered and reused although their catalytic activity descend gradually as a result of the decrease in their cobalt content.

  16. Synthesis, Crystal Structure and Magnetic Properties of a New 3D Cobalt Vanadate

    Institute of Scientific and Technical Information of China (English)

    WANG,Lei(王磊); ZHANG,Hong(张宏); ZHANG,Jing-Ping(张景萍); NIU,Ben(牛犇); CUI,Shu-Xin(崔术新)

    2004-01-01

    A new cobalt vanadate compound 1 [CoⅡ(H2O)2 Vv2 O6] has been hydrothermally synthesized and characterized by the elemental analyses and the single crystal X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic system, space group Pmna, with a=0.55646, b= 1.06900, c= 1.18452 nm, and Z=4. The magnetic susceptibility of the cobalt vanadate has been measured and indicates possible antiferromagnetic coupling between adjacent cobalt (Ⅱ) (0.5432-0.5697 nm) through bond or space.

  17. Performances of Aluminum-cobalt Co-substituted α-Ni(OH)2 Electrodes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-bin; LIU Han-san; CAO Xue-jing; SUN Chia-chung

    2004-01-01

    Aluminum-cobalt co-substituted α-Ni(OH)2 was prepared by means of the titration method in a buffer solution, the structure was characterized by XRD analysis. With above mentioned α-Ni(OH)2 as the positive electrode of a nickel-metal hydride cell, the discharge performances were examined by constant-current charge-discharge experiments. In comparison with the electrodes made of aluminum substituted or cobalt substituted Ni(OH)2 materials, the aluminum-cobalt co-substituted composite electrodes possess an excellent electrochemical performance and are of practical significance.

  18. China’s Cobalt Output Expected to Reach 8,600 Tons in 2004

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正> During the period from January to July thisyear,China imported 72,000 tons of cobaltconcentrates, up by 63.78 per cent comparedwith the same period of last year.Import of co-balt concentrates this year is not only large inquantity but also spreads over wide areas inChina.Besides the traditional cobalt producersin Ganzhou, Jiangxi province where import ofcobalt concentrates reached 30,900 tons,ac-counting for almost half of the total import inChina with the importers including the Gan-zhou Cobalt Smelter and a number of othersmaller producers there.A number of other

  19. Synthesis, Characterization, and Electrochemistry of sigma-Bonded Cobalt Corroles in High Oxidation States.

    Science.gov (United States)

    Will, Stefan; Lex, Johann; Vogel, Emanuel; Adamian, Victor A.; Van Caemelbecke, Eric; Kadish, Karl M.

    1996-09-11

    The synthesis, electrochemistry, spectroscopy, and structural characterization of two high-valent phenyl sigma-bonded cobalt corroles containing a central cobalt ion in formal +IV and +V oxidation states is presented. The characterized compounds are represented as phenyl sigma-bonded cobalt corroles, (OEC)Co(C(6)H(5)) and [(OEC)Co(C(6)H(5))]ClO(4), where OEC is the trianion of 2,3,7,8,12,13,17,18-octaethylcorrole. The electronic distribution in both molecules is discussed in terms of their NMR and EPR spectroscopic data, magnetic susceptibility, and electrochemistry.

  20. Influence of Cobalte Octoate on Degree of Cure and Flexural Strength of an Unsaturated Polyester Resin

    Institute of Scientific and Technical Information of China (English)

    R; M; Gengan; K; Moodley

    2007-01-01

    1 Introduction In the GRP (Glass fibre Reinforced Product) industry Cobalt Octoate is the promoter of choice for cross-linking unsaturated polyester (UPE) and styrene monomer.UPE's are often prepared to contain a concentration of 0.04%-0.05% of Cobalt ions so that faster cross-linking of the resin is achieved and ultimately faster manufacturing of the GRP component is achieved.These products sometimes fail prematurely after being manufactured and dispatched to the end user.The influence of Cobalt Octoat...