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

PubMed

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

2018-05-01

While cobalt is an essential micronutrient for vitamin B 12 synthesis in the horse, at supraphysiological concentrations, it has been shown to enhance performance in human subjects and rats, and there is evidence that its administration in high doses to horses poses a welfare threat. Animal sport regulators currently control cobalt abuse via international race day thresholds, but this work was initiated to explore means of potentially adding to application of those thresholds since cobalt may be present in physiological concentrations. To devise a scientific basis for differentiation between presence of cobalt from bona fide supplementation and cobalt doping through the use of ratios. Six Thoroughbred horses were given 10 mL vitamin B 12 /cobalt supplement (Hemo-15 ® ; Vetoquinol, Buckingham, Buckinghamshire, UK., 1.5 mg B 12 , 7 mg cobalt gluconate = 983 μg total Co) as an i.v. bolus then an i.v. infusion (15 min) of 100 mg cobalt chloride (45.39 mg Co) 6 weeks later. Pre-and post-administration plasma and urine samples were analysed for cobalt and vitamin B 12 . Urine and plasma samples were analysed for vitamin B 12 using an immunoassay and cobalt concentrations were measured via ICP-MS. Baseline concentrations of cobalt in urine and plasma for each horse were subtracted from their cobalt concentrations post-administration for the PK analysis. Compartmental analysis was used for the determination of plasma PK parameters for cobalt using commercially available software. On administration of a vitamin B 12 /cobalt supplement, the ratio of cobalt to vitamin B 12 in plasma rapidly increased to approximately 3 and then rapidly declined below a ratio of 1 and then back to near baseline over the next week. On administration of 100 mg cobalt chloride, the ratio initially exceeded 10 in plasma and then declined with the lower 95% confidence interval remaining above a ratio of 1 for 7 days. For two horses with extended sampling, the plasma ratio remained above one for approximately 28 days after cobalt chloride administration. The effect of the administration of the vitamin B 12 /cobalt supplement on the urine ratio was transient and reached a peak value of 10 which then rapidly declined. However, a urine ratio of 10 was exceeded, with the lower 95% confidence interval remaining above a ratio of 10 for 7 days after cobalt chloride administration. For the two horses with extended sampling, the urine ratio remained above 10 for about 18 days (442 h) after cobalt chloride administration even though the absolute cobalt urine concentration had dropped below the international threshold of 100 ng/mL after 96 h. Only one vitamin B 12 /cobalt product was evaluated, a limited number of horses were included, the horses were not in full race training and the results may be specific to this population of horses. The results provide the basis for a potential strategy for allowing supplementation with vitamin B 12 products, while controlling the misuse of high doses of cobalt, through a combination of international thresholds and ratios of cobalt to vitamin B 12 , in plasma and urine. © 2017 EVJ Ltd.

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

PubMed Central

2013-01-01

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. PMID:24229351

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

USDA-ARS?s Scientific Manuscript database

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...

Selective catalysts and their preparation for catalytic hydrocarbon synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iglesia, E.; Vroman, H.; Soled, S.

1991-07-30

This patent describes a method for preparing a supported cobalt catalyst particle. It comprises contacting a support particle with a molten cobalt salt, for a period sufficient to impregnate substantially all of the molten cobalt salt on the support to a depth of less than about 200 {mu}m; drying the supported cobalt salt obtained; reducing the cobalt of the supported cobalt salt to metallic cobalt by heating the salt in the presence of H{sub 2}, wherein the heating is conducted at a rate of less than about 1{degrees} C./min. up to a maximum temperature ranging from about 100{degrees} C. tomore » about 500{degrees} C., to produce a supported cobalt catalyst particle.« less

Mechanical properties of nanocrystalline cobalt

NASA Astrophysics Data System (ADS)

Karimpoor, Amir A.; Erb, Uwe

2006-05-01

Due to their excellent wear and corrosion properties, nanocrystalline cobalt and several cobalt alloys made by electrodeposition are currently being developed as environmentally benign replacement coatings for hard chromium electrodeposits. The focus of this study is on the mechanical properties of nanocrystalline cobalt, which are currently not well understood. A comparison is presented for hardness, tensile properties, Charpy impact properties and fracture surface analysis of both nanocrystalline (grain size: 12 nm) and conventional polycrystalline (grain size: 4.8 m) cobalt. It is shown that the hardness and tensile strength of nanocrystalline cobalt is 2-3 times higher than for polycrystalline cobalt. However, in contrast to other nanocrystalline materials tested previously, nanocrystalline cobalt retains considerable ductility with elongation to fracture values up to 7%.

Cobalt: A vital element in the aircraft engine industry

NASA Technical Reports Server (NTRS)

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.

Characteristics of polyaniline cobalt supported catalysts for epoxidation reactions.

PubMed

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.

Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

PubMed Central

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

The Role of External Inputs and Internal Cycling in Shaping the Global Ocean Cobalt Distribution: Insights From the First Cobalt Biogeochemical Model

NASA Astrophysics Data System (ADS)

Tagliabue, Alessandro; Hawco, Nicholas J.; Bundy, Randelle M.; Landing, William M.; Milne, Angela; Morton, Peter L.; Saito, Mak A.

2018-04-01

Cobalt is an important micronutrient for ocean microbes as it is present in vitamin B12 and is a co-factor in various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt is compared to biological demands, cobalt emerges as being depleted in seawater, pointing to a potentially important limiting role. To properly account for the potential biological role for cobalt, there is therefore a need to understand the processes driving the biogeochemical cycling of cobalt and, in particular, the balance between external inputs and internal cycling. To do so, we developed the first cobalt model within a state-of-the-art three-dimensional global ocean biogeochemical model. Overall, our model does a good job in reproducing measurements with a correlation coefficient of >0.7 in the surface and >0.5 at depth. We find that continental margins are the dominant source of cobalt, with a crucial role played by supply under low bottom-water oxygen conditions. The basin-scale distribution of cobalt supplied from margins is facilitated by the activity of manganese-oxidizing bacteria being suppressed under low oxygen and low temperatures, which extends the residence time of cobalt. Overall, we find a residence time of 7 and 250 years in the upper 250 m and global ocean, respectively. Importantly, we find that the dominant internal resupply process switches from regeneration and recycling of particulate cobalt to dissolution of scavenged cobalt between the upper ocean and the ocean interior. Our model highlights key regions of the ocean where biological activity may be most sensitive to cobalt availability.

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

PubMed

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fabrication of cobalt magnetic nanostructures using atomic force microscope lithography.

PubMed

Chu, Haena; Yun, Seonghun; Lee, Haiwon

2013-12-01

Cobalt nanopatterns are promising assemblies for patterned magnetic storage applications. The fabrication of cobalt magnetic nanostructures on n-tridecylamine x hydrochloride (TDA x HCl) self-assembled monolayer (SAM) modified silicon surfaces using direct writing atomic force microscope (AFM) lithography for localized electrochemical reduction of cobalt ions was demonstrated. The ions were reduced to form metal nanowires along the direction of the electricfield between the AFM tip and the substrate. In this lithography process, TDA x HCI SAMs play an important role in the lithography process for improving the resolution of cobalt nanopatterns by preventing nonspecific reduction of cobalt ions on the unwritten background. Cobalt nanowires and nanodots with width of 225 +/- 26 nm and diameter of 208 +/- 28 nm were successfully fabricated. Platinium-coated polydimethylsiloxane (PDMS) stamp was used fabricating bulk cobalt structures which can be detected by energy dispersive X-ray spectroscopy for element analysis and the physical and magnetic properties of these cobalt nanopatterns were characterized using AFM and magnetic force microscope.

Influence of Cobalt Doping on the Physical Properties of Zn0.9Cd0.1S Nanoparticles

PubMed Central

2010-01-01

Zn0.9Cd0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn0.9Cd0.1S sphalerite phase. For low cobalt concentration (≤0.05 M) particle size, dXRDis ~3.5 nm, while for high cobalt concentration (>0.05 M) particle size decreases abruptly (~2 nm) as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm) irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration. PMID:20672097

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

PubMed

Lippi, Giuseppe; Franchini, Massimo; Guidi, Gian Cesare

2006-07-24

Blood doping is commonplace in competitive athletes who seek to enhance their aerobic performances through illicit techniques. 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. 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. 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.

Influence of Cobalt Doping on the Physical Properties of Zn0.9Cd0.1S Nanoparticles.

PubMed

Singhal, Sonal; Chawla, Amit Kumar; Gupta, Hari Om; Chandra, Ramesh

2009-11-17

Zn0.9Cd0.1S nanoparticles doped with 0.005-0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn0.9Cd0.1S sphalerite phase. For low cobalt concentration (≤0.05 M) particle size, dXRDis ~3.5 nm, while for high cobalt concentration (>0.05 M) particle size decreases abruptly (~2 nm) as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm) irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie-Weiss temperature of -75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.

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

PubMed

Kinobe, Robert T

2016-02-01

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

Consumer leather exposure: an unrecognized cause of cobalt sensitization.

PubMed

Thyssen, Jacob P; Johansen, Jeanne D; Jellesen, Morten S; Møller, Per; Sloth, Jens J; Zachariae, Claus; Menné, Torkil

2013-11-01

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. 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. 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. Cobalt is used in the so-called pre-metallized dyeing of leather products. Repeated studies have found high levels of cobalt sensitization, but not nickel sensitization, in patients with foot dermatitis. We raise the possibility that cobalt may be widely released from leather items, and advise dermatologists to consider this in patients with positive cobalt patch test reactions. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

DOEpatents

Bates, John B.

2003-04-29

Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

DOEpatents

Bates, John B.

2002-01-01

Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

DOEpatents

Bates, John B.

2003-05-13

Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

Cobalt.

PubMed

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.

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

PubMed Central

Lippi, Giuseppe; Franchini, Massimo; Guidi, Gian Cesare

2006-01-01

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 PMID:16863591

In situ diagnosis of pulsed UV laser surface ablation of tungsten carbide hardmetal by using laser-induced optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Li, Tiejun; Lou, Qihong; Wei, Yunrong; Huang, Feng; Dong, Jingxing; Liu, Jingru

2001-12-01

Surface ablation of cobalt cemented tungsten carbide hardmetal with pulsed UV laser has been in situ diagnosed by using the technique of laser-induced optical emission spectroscopy. The dependence of emission intensity of cobalt lines on number of laser shots was investigated at laser fluence of 2.5 J/cm 2. As a comparison, the reliance of emission intensity of cobalt lines as a function of laser pulse number by using pure cobalt as ablation sample was also studied at the same laser condition. It was found that for surface ablation of tungsten carbide hardmetal at laser fluence of 2.5 J/cm 2, the intensities of cobalt lines fell off dramatically in the first 300 consecutive laser shots and then slowed down to a low stable level with even more shots. For surface ablation of pure cobalt at the same laser condition, the intensities of cobalt lines remained constant more or less even after 500 laser shots and then reduced very slowly with even more shots. It was concluded that selective evaporation of cobalt at this laser fluence should be responsible for the dramatic fall-off of cobalt lines with laser shots accumulation for surface ablation of tungsten carbide hardmetal. In contrast, for surface ablation of pure cobalt, the slow reduction of cobalt lines with pulse number accumulation should be due to the formation of laser-induced crater effect.

Cobalt recycling in the United States in 1998

USGS Publications Warehouse

Shedd, Kim B.

2002-01-01

This report is one of a series of reports on metals recycling. It defines and quantifies the 1998 flow of cobalt-bearing materials in the United States, from imports and stock releases through consumption and disposition, with particular emphasis on the recycling of industrial scrap (new scrap) and used products (old scrap). Because of cobalt?s many and diverse uses, numerous types of scrap were available for recycling by a wide variety of processes. In 1998, an estimated 32 percent of U.S. cobalt supply was derived from scrap. The ratio of cobalt consumed from new scrap to that from old scrap was estimated to be 50:50. Of all the cobalt in old scrap available for recycling, an estimated 68 percent was either consumed in the United States or exported to be recycled.

[Effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes].

PubMed

Qiuxia, Yang; Ying, Yang; Han, Xu; Di, Wu; Ke, Guo

2016-02-01

This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes in a simulated oral environment. A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH = 5.0). The specimens were soaked in fluorine for 24 h, and the surface microstructure was observed under a field emission scanning electron microscope after immersing the specimens in the test solution at constant temperature. The corrosion potential (Ecorr) value of the cobalt-chromium alloy cast decreased with increasing fluoride concentration in acidic artificial saliva. The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes changed significantly when the fluoride concentration was 0.20% (P < 0.05). The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes exhibited a statistically significant difference. The Icorr value of the cobalt-chromium alloy cast was higher than that in the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P < 0.05). The Ecorr, tRp alues of the cobalt-chromium alloy cast were lower htan those of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P< 0 .05). Fluoride ions adversely affected the corrosion resistance of the cobalt-chromium alloy fabricated by two different technology processes. The corrosion resistance of the cobalt-chromium alloy cast was worse than that of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20%.

Separation and Recovery of Cobalt from Copper Leach Solutions

NASA Astrophysics Data System (ADS)

Jeffers, T. H.

1985-01-01

Significant amounts of cobalt, a strategic and critical metal, are present in readily accessible copper recycling leach solutions. However, cost-effective technology is not available to separate and recover the cobalt from this low-grade domestic source. The Bureau of Mines has developed a procedure using a chelating ion-exchange resin from Dow Chemical Co. to successfully extract cobalt from a pH 3.0 copper recycling solution containing only 30 mg/1 cobalt. Cyclic tests with the commercial resin XFS-4195 in 4-ft-high by 1-in.-diameter columns gave an average cobalt extraction of 95% when 65 bed volumes of solution were processed at a flow rate of 4 gpm/ft.2 Elution of the cobalt using a 50 g/l H2SO4 solution yielded an eluate containing 0.5 gli Co. Selective elution of the loaded resin and solvent extraction procedures using di-2-ethylhexyl phosphoric acid (D2EHPA) and Cyanex 272 removed the impurities and produced a cobalt sulfate solution containing 25 g/l Co.

Cobalt—Styles of deposits and the search for primary deposits

USGS Publications Warehouse

Hitzman, Murray W.; Bookstrom, Arthur A.; Slack, John F.; Zientek, Michael L.

2017-11-30

Cobalt (Co) is a potentially critical mineral. The vast majority of cobalt is a byproduct of copper and (or) nickel production. Cobalt is increasingly used in magnets and rechargeable batteries. More than 50 percent of primary cobalt production is from the Central African Copperbelt. The Central African Copperbelt is the only sedimentary rock-hosted stratiform copper district that contains significant cobalt. Its presence may indicate significant mafic-ultramafic rocks in the local basement. The balance of primary cobalt production is from magmatic nickel-copper and nickel laterite deposits. Cobalt is present in several carbonate-hosted lead-zinc and copper districts. It is also variably present in Besshi-type volcanogenic massive sulfide and siliciclastic sedimentary rock-hosted deposits in back arc and rift environments associated with mafic-ultramafic rocks. Metasedimentary cobalt-copper-gold deposits (such as Blackbird, Idaho), iron oxide-copper-gold deposits, and the five-element vein deposits (such as Cobalt, Ontario) contain different amounts of cobalt. None of these deposit types show direct links to mafic-ultramafic rocks; the deposits may result from crustal-scale hydrothermal systems capable of leaching and transporting cobalt from great depths. Hydrothermal deposits associated with ultramafic rocks, typified by the Bou Azzer district of Morocco, represent another type of primary cobalt deposit.In the United States, exploration for cobalt deposits may focus on magmatic nickel-copper deposits in the Archean and Proterozoic rocks of the Midwest and the east coast (Pennsylvania) and younger mafic rocks in southeastern and southern Alaska; also, possibly basement rocks in southeastern Missouri. Other potential exploration targets include—The Belt-Purcell basin of British Columbia (Canada), Idaho, Montana, and Washington for different styles of sedimentary rock-hosted cobalt deposits;Besshi-type VMS deposits, such as the Greens Creek (Alaska) deposit and the Ducktown (Tennessee) waste and tailings; andKnown five-element vein districts in Arizona and New Mexico, as well as in the Yukon-Tanana terrane of Alaska; and hydrothermal deposits associated with ultramafic rocks along the west coast, in Alaska, and in the Appalachian Mountains.

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

PubMed

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 < 0.01) with the athletes' samples presenting slightly higher urinary 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 required to elucidate further factors potentially influencing urinary cobalt levels. Copyright © 2014 John Wiley & Sons, Ltd.

In Situ Characterization of Mesoporous Co/CeO 2 Catalysts for the High-Temperature Water-Gas Shift

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vovchok, Dimitriy; Guild, Curtis J.; Dissanayake, Shanka

Here, mesoporous Co/CeO 2 catalysts were found to exhibit significant activity for the high-temperature water-gas shift (WGS) reaction with cobalt loadings as low as 1 wt %. The catalysts feature a uniform dispersion of cobalt within the CeO 2 fluorite type lattice with no evidence of discrete cobalt phase segregation. In situ XANES and ambient pressure XPS experiments were used to elucidate the active state of the catalysts as partially reduced cerium oxide doped with oxidized cobalt atoms. In situ XRD and DRIFTS experiments suggest facile cerium reduction and oxygen vacancy formation, particularly with lower cobalt loadings. In situ DRIFTSmore » analysis also revealed the presence of surface carbonate and bidentate formate species under reaction conditions, which may be associated with additional mechanistic pathways for the WGS reaction. Deactivation behavior was observed with higher cobalt loadings. XANES data suggest the formation of small metallic cobalt clusters at temperatures above 400 °C may be responsible. Notably, this deactivation was not observed for the 1% cobalt loaded catalyst, which exhibited the highest activity per unit of cobalt.« less

The role of cobalt on the creep of Waspaloy

NASA Technical Reports Server (NTRS)

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

1984-01-01

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

Metallic phases of cobalt-based catalysts in ethanol steam reforming: The effect of cerium oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Sean S.-Y.; Kim, Do Heui; Ha, Su Y.

2009-02-28

The catalytic activity of cobalt in the production of hydrogen via ethanol steam reforming has been investigated in its relation to the crystalline structure of metallic cobalt. At a reaction temperature of 350 8C, the specific hydrogen production rates show that hexagonal close-packed (hcp) cobalt possesses higher activity than face-centered cubic (fcc) cobalt. However, at typical reaction temperatures (400– 500 8C) for ethanol steam reforming, hcp cobalt is transformed to less active fcc cobalt, as confirmed by in situ X-ray diffractometry (XRD). The addition of CeO2 promoter (10 wt.%) stabilizes the hcp cobalt structure at reforming temperatures up to 600more » 8C. Moreover, during the pre-reduction process, CeO2 promoter prevents sintering during the transformation of Co3O4 to hcp cobalt. Both reforming experiments and in situ diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that the surface reactions were modified by CeO2 promoter on 10% Ce–Co (hcp) to give a lower CO selectivity and a higher H2 yield as compared with the unpromoted hcp Co.« less

In Situ Characterization of Mesoporous Co/CeO 2 Catalysts for the High-Temperature Water-Gas Shift

DOE PAGES

Vovchok, Dimitriy; Guild, Curtis J.; Dissanayake, Shanka; ...

2018-04-04

Here, mesoporous Co/CeO 2 catalysts were found to exhibit significant activity for the high-temperature water-gas shift (WGS) reaction with cobalt loadings as low as 1 wt %. The catalysts feature a uniform dispersion of cobalt within the CeO 2 fluorite type lattice with no evidence of discrete cobalt phase segregation. In situ XANES and ambient pressure XPS experiments were used to elucidate the active state of the catalysts as partially reduced cerium oxide doped with oxidized cobalt atoms. In situ XRD and DRIFTS experiments suggest facile cerium reduction and oxygen vacancy formation, particularly with lower cobalt loadings. In situ DRIFTSmore » analysis also revealed the presence of surface carbonate and bidentate formate species under reaction conditions, which may be associated with additional mechanistic pathways for the WGS reaction. Deactivation behavior was observed with higher cobalt loadings. XANES data suggest the formation of small metallic cobalt clusters at temperatures above 400 °C may be responsible. Notably, this deactivation was not observed for the 1% cobalt loaded catalyst, which exhibited the highest activity per unit of cobalt.« less

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

DTIC Science & Technology

2013-12-01

although contact with cobalt can cause dermatitis [16]. While cobalt is known to cause adverse health effects, the exact mechanism of action remains...animals and humans through various exposure routes. Cobalt can enter the body through respiration, ingestion, or contact with the skin. The adverse...concentration on the liver, kidney and heart in mice. Orthop Surg 2: 134–140. 16. Schwartz L PS (1945) Allergic dermatitis due to metallic cobalt. Journal

Complete cobalt recovery from lithium cobalt oxide in self-driven microbial fuel cell - Microbial electrolysis cell systems

NASA Astrophysics Data System (ADS)

Huang, Liping; Yao, Binglin; Wu, Dan; Quan, Xie

2014-08-01

Complete cobalt recovery from lithium cobalt oxide requires to firstly leach cobalt from particles LiCoO2 and then recover cobalt from aqueous Co(II). A self-driven microbial fuel cell (MFC)-microbial electrolysis cell (MEC) system can completely carry out these two processes, in which Co(II) is firstly released from particles LiCoO2 on the cathodes of MFCs and then reduced on the cathodes of MECs which are powered by the cobalt leaching MFCs. A cobalt leaching rate of 46 ± 2 mg L-1 h-1 with yield of 1.5 ± 0.1 g Co g-1 COD (MFCs) and a Co(II) reduction rate of 7 ± 0 mg L-1 h-1 with yield of 0.8 ± 0.0 g Co g-1 COD (MECs), as well as a overall system cobalt yield of 0.15 ± 0.01 g Co g-1 Co can be achieved in this self-driven MFC-MEC system. Coulombic efficiencies reach 41 ± 1% (anodic MFCs), 75 ± 0% (anodic MECs), 100 ± 2% (cathodic MFCs), and 29 ± 1% (cathodic MECs) whereas overall system efficiency averages 34 ± 1%. These results provide a new process of linking MFCs to MECs for complete recovery of cobalt and recycle of spent lithium ion batteries with no external energy consumption.

Process for cobalt separation and recovery in the presence of nickel from sulphate solutions by Cyanex 272

NASA Astrophysics Data System (ADS)

Park, Kyung-Ho; Mohapatra, Debasish

2006-10-01

The present paper deals with the extraction of cobalt from a solution containing cobalt and nickel in a sulphate medium similar to the leach liquor obtained by the dilute sulphuric acid pressure leaching of the Pacific Ocean nodules matte followed by copper extraction. The commercial extractant Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid) is used for this purpose. The leach liquor used for the present study contains Co =1.78 g/L and Ni=16.78 g/L. Before cobalt extraction, impurities, such as copper and iron, are removed from the leach liquor by the precipitation method. Increasing the concentration of Cyanex 272 increased the extraction percentage of cobalt due to the increase of equilibrium pH. Cobalt extraction efficiency of >99.9 % is achieved with 0.20 M Cyanex 272 in two counter-current stages at an aqueous: organic (A:O) phase ratio of 1.5∶1. Complete stripping of cobalt from the loaded organic containing 2.73 g/L Co was carried out at pH 1.4 by a synthetic cobalt spent electrolyte in two stages at an A:O ratio of 1∶2. The enrichment of cobalt during extraction and stripping operations was about 3.5 times. A complete process flowsheet for the separation and recovery of cobalt is presented.

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

Palladium-cobalt particles as oxygen-reduction electrocatalysts

DOEpatents

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

2009-12-15

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

Liesegang banding and multiple precipitate formation in cobalt phosphate systems

NASA Astrophysics Data System (ADS)

Karam, Tony; El-Rassy, Houssam; Zaknoun, Farah; Moussa, Zeinab; Sultan, Rabih

2012-02-01

We study a cobalt phosphate Liesegang pattern from cobalt(II) and phosphate ions in a 1D tube. The system yields a complex, multi-component pattern. Characterization of the different precipitates by FTIR, SEM and XRD reveals that they are cobalt phosphate polymorphs with different degrees of hydration.

21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining a... percent each) of oxides of barium, boron, silicon, and nickel. (b) Specifications. Chromium-cobalt... milliliters of 0.5 N hydrochloric acid. (c) Uses and restrictions. The color additive chromium-cobalt-aluminum...

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

USDA-ARS?s Scientific Manuscript database

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...

Comparison of different supplemental cobalt forms on digestion and cobalamin levels

USDA-ARS?s Scientific Manuscript database

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...

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

DTIC Science & Technology

2013-12-30

exposures are unlikely to have systemic effects as cobalt cannot readily penetrate normal skin, although contact with cobalt can cause dermatitis [16...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...Surg 2: 134–140. 16. Schwartz L PS (1945) Allergic dermatitis due to metallic cobalt. Journal of Allergy 16: 51–53. 17. De Matteis F, Gibbs AH (1977

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-18

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

40 CFR 721.10600 - Calcium cobalt lead strontium titanium tungsten oxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Calcium cobalt lead strontium titanium... Specific Chemical Substances § 721.10600 Calcium cobalt lead strontium titanium tungsten oxide. (a... calcium cobalt lead strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0) is subject to...

40 CFR 721.10600 - Calcium cobalt lead strontium titanium tungsten oxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Calcium cobalt lead strontium titanium... Specific Chemical Substances § 721.10600 Calcium cobalt lead strontium titanium tungsten oxide. (a... calcium cobalt lead strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0) is subject to...

Thermal-fatigue and oxidation resistance of cobalt-modified Udimet 700 alloy

NASA Technical Reports Server (NTRS)

Bizon, P. T.; Barrow, B. J.

1986-01-01

Comparative thermal-fatigue and oxidation resistances of cobalt-modified wrought Udimet 700 alloy (obtained by reducing the cobalt level by direct substitution of nickel) were determined from fluidized-bed tests. Bed temperatures were 1010 and 288 C (1850 and 550 C) for the first 5500 symmetrical 6-min cycles. From cycle 5501 to the 14000-cycle limit of testing, the heating bed temperature was increased to 1050 C (1922 F). Cobalt levels between 0 and 17 wt% were studied in both the bare and NiCrAlY overlay coated conditions. A cobalt level of about 8 wt% gave the best thermal-fatigue life. The conventional alloy specification is for 18.5% cobalt, and hence, a factor of 2 in savings of cobalt could be achieved by using the modified alloy. After 13500 cycles, all bare cobalt-modified alloys lost 10 to 13 percent of their initial weight. Application of the NiCrAlY overlay coating resulted in weight losses of 1/20 to 1/100 of that of the corresponding bare alloy.

Selective Area Band Engineering of Graphene using Cobalt-Mediated Oxidation.

PubMed

Bazylewski, Paul F; Nguyen, Van Luan; Bauer, Robert P C; Hunt, Adrian H; McDermott, Eamon J G; Leedahl, Brett D; Kukharenko, Andrey I; Cholakh, Seif O; Kurmaev, Ernst Z; Blaha, Peter; Moewes, Alexander; Lee, Young Hee; Chang, Gap Soo

2015-10-21

This study reports a scalable and economical method to open a band gap in single layer graphene by deposition of cobalt metal on its surface using physical vapor deposition in high vacuum. At low cobalt thickness, clusters form at impurity sites on the graphene without etching or damaging the graphene. When exposed to oxygen at room temperature, oxygen functional groups form in proportion to the cobalt thickness that modify the graphene band structure. Cobalt/Graphene resulting from this treatment can support a band gap of 0.30 eV, while remaining largely undamaged to preserve its structural and electrical properties. A mechanism of cobalt-mediated band opening is proposed as a two-step process starting with charge transfer from metal to graphene, followed by formation of oxides where cobalt has been deposited. Contributions from the formation of both CoO and oxygen functional groups on graphene affect the electronic structure to open a band gap. This study demonstrates that cobalt-mediated oxidation is a viable method to introduce a band gap into graphene at room temperature that could be applicable in electronics applications.

Determination of cobalt species in nutritional supplements using ICP-OES after microwave-assisted extraction and solid-phase extraction.

PubMed

Bartosiak, Magdalena; Jankowski, Krzysztof; Giersz, Jacek

2018-06-05

Cobalt content (as vitamin B 12 and inorganic cobalt) in two nutritional supplements, namely Spirulina platensis and Saccharomyces cerevisiae known as a "superfood", has been determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Several sample pre-treatment protocols have been applied and compared. Microwave-assisted acid digestion efficiently decomposed all cobalt-containing compounds, thus allowed obtaining total cobalt content in supplements examined. Vitamin B 12 was extracted from the samples with acetate buffer and potassium cyanide solution exposed to mild microwave radiation for 30 min, and cyanocobalamin was separated from the extract by on-column solid phase extraction using C-18 modified silica bed. About 100% of cobalt species was extracted using the triple microwave-assisted extraction procedure. Total cobalt content was 20-fold greater in Spirulina tablets than the declared cobalamin content (as Co). The ICP-OES method precision was about 3% and detection limit was 1.9 and 2.7 ng Co mL -1 for inorganic cobalt or cyanocobalamin, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

Studies on KIT-6 Supported Cobalt Catalyst for Fischer–Tropsch Synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gnanamani, M.; Jacobs, G; Graham, U

2010-01-01

KIT-6 molecular sieve was used as a support to prepare cobalt catalyst for Fischer-Tropsch synthesis (FTS) using an incipient wetness impregnation method to produce cobalt loadings of 15 and 25 wt%. The catalysts were characterized by BET surface area, X-ray diffraction, scanning transmission election microscopy (STEM), extended X-ray absorption fine spectroscopy and X-ray absorption near edge spectroscopy. The catalytic properties for FTS were evaluated using a 1L CSTR reactor. XRD, pore size distribution, and STEM analysis indicate that the KIT-6 mesostructure remains stable during and after cobalt impregnation and tends to form smaller cobalt particles, probably located inside the mesopores.more » The mesoporous KIT-6 exhibited a slightly higher cobalt dispersion compared to amorphous SiO{sub 2} supported catalyst. With the higher Co loading (25 wt%) on KIT-6, partial structural collapse was observed after the FTS reaction. Compared to an amorphous SiO{sub 2} supported cobalt catalyst, KIT-6 supported cobalt catalyst displayed higher methane selectivity at a similar Co loading, likely due to diffusion effects.« less

Selective Area Band Engineering of Graphene using Cobalt-Mediated Oxidation

PubMed Central

Bazylewski, Paul F.; Nguyen, Van Luan; Bauer, Robert P.C.; Hunt, Adrian H.; McDermott, Eamon J. G.; Leedahl, Brett D.; Kukharenko, Andrey I.; Cholakh, Seif O.; Kurmaev, Ernst Z.; Blaha, Peter; Moewes, Alexander; Lee, Young Hee; Chang, Gap Soo

2015-01-01

This study reports a scalable and economical method to open a band gap in single layer graphene by deposition of cobalt metal on its surface using physical vapor deposition in high vacuum. At low cobalt thickness, clusters form at impurity sites on the graphene without etching or damaging the graphene. When exposed to oxygen at room temperature, oxygen functional groups form in proportion to the cobalt thickness that modify the graphene band structure. Cobalt/Graphene resulting from this treatment can support a band gap of 0.30 eV, while remaining largely undamaged to preserve its structural and electrical properties. A mechanism of cobalt-mediated band opening is proposed as a two-step process starting with charge transfer from metal to graphene, followed by formation of oxides where cobalt has been deposited. Contributions from the formation of both CoO and oxygen functional groups on graphene affect the electronic structure to open a band gap. This study demonstrates that cobalt-mediated oxidation is a viable method to introduce a band gap into graphene at room temperature that could be applicable in electronics applications. PMID:26486966

Cyanide speciation at four gold leach operations undergoing remediation

USGS Publications Warehouse

Johnson, Craig A.; Grimes, David J.; Leinz, Reinhard W.; Rye, Robert O.

2008-01-01

Analyses have been made of 81 effluents from four gold leach operations in various stages of remediation to identify the most-persistent cyanide species. Total cyanide and weak acid-dissociable (WAD) cyanide were measured using improved methods, and metals known to form stable cyanocomplexes were also measured. Typically, total cyanide greatly exceeded WAD indicating that cyanide was predominantly in strong cyanometallic complexes. Iron was generally too low to accommodate the strongly complexed cyanide as Fe(CN)63- or Fe(CN)64-, but cobalt was abundant enough to implicate Co(CN)63- or its dissociation products (Co(CN)6-x(H2O)x(3-x)-). Supporting evidence for cobalt-cyanide complexation was found in tight correlations between cobalt and cyanide in some sample suites. Also, abundant free cyanide was produced upon UV illumination. Iron and cobalt cyanocomplexes both photodissociate; however, the iron concentration was insufficient to have carried the liberated cyanide, while the cobalt concentration was sufficient. Cobalt cyanocomplexes have not previously been recognized in cyanidation wastes. Their identification at four separate operations, which had treated ores that were not especially rich in cobalt, suggests that cobalt complexation may be a common source of cyanide persistence. There is a need for more information on the importance and behavior of cobalt cyanocomplexes in ore-processing wastes at gold mines.

Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation

PubMed Central

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

Phosphorus-31 and carbon-13 nuclear magnetic resonance studies of divalent cation binding to phosphatidylserine membranes. Use of cobalt as a paramagnetic probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLaughlin, A.C.

1982-01-01

The paramagnetic divalent cation cobalt has large and well-understood effects on NMR signals from ligands bound in the first coordination sphere, i.e., inner-sphere ligands, and the authors have used these effects to identify divalent cation binding sites at the surface of phosphatidylserine membranes. /sup 31/P NMR results show that 13% of the bound cobalt ions are involved in inner-sphere complexes with the phosphodiester group, while /sup 13/C NMR results show that 54% of the bound cobalt ions are involved in unidentate inner sphere complexes with the carboxyl group. No evidence is found for cobalt binding to the carbonyl groups, butmore » proton release studies suggest that 32% of the bound cobalt ions are involved in chelate complexes that contain both the carboxyl and the amine groups. All of the bound cobalt ions can thus be accounted for in terms of inner sphere complexes with the phosphodiester group or the carboxyl group. They suggest that the unidentate inner-sphere complex between cobalt and the carboxyl group of phosphatidylserine and the inner-sphere complex between cobalt and the phosphodiester group of phosphatidylserine provide reasonable models for complexes between alkaline earth cations and phosphatidylserine membranes.« less

Phosphorus-31 and carbon-13 nuclear magnetic resonance studies of divalent cation binding to phosphatidylserine membranes: use of cobalt as a paramagnetic probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLaughlin, A.C.

1982-09-28

The paramagnetic divalent cation cobalt has large and well-understood effects on NMR signals from ligands bound in the first coordination sphere, i.e., inner-sphere ligands, and we have used these effects to identify divalent cation binding sites at the surface of phosphatidylserine membranes. /sup 31/P NMR results show that 13% of the bound cobalt ions are involved in inner-sphere complexes with the phosphodiester group, while /sup 13/C NMR results show that 54% of the bound cobalt ions are involved in unidentate inner sphere complexes with the carboxyl group. No evidence is found for cobalt binding to the carbonyl groups, but protonmore » release studies suggest that 32% of the bound cobalt ions are involved in chelate complexes that contain both the carboxyl and the amine groups. All (i.e., 13% + 54% + 32% = 99%) of the bound cobalt ions can thus be accounted for in terms of inner sphere complexes with the phosphodiester group or the carboxyl group. We suggest that the unidentate inner-sphere complex between cobalt and the carboxyl group of phosphatidylserine and the inner-sphere complex between cobalt and the phosphodiester group of phosphatidylserine provide reasonable models for complexes between alkaline earth cations and phosphatidylserine membranes.« less

Cobalt asthma in metalworkers from an automotive engine valve manufacturer.

PubMed

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.

Cobalt distribution in keratinocyte cells indicates nuclear and perinuclear accumulation and interaction with magnesium and zinc homeostasis.

PubMed

Ortega, Richard; Bresson, Carole; Fraysse, Aurélien; Sandre, Caroline; Devès, Guillaume; Gombert, Clémentine; Tabarant, Michel; Bleuet, Pierre; Seznec, Hervé; Simionovici, Alexandre; Moretto, Philippe; Moulin, Christophe

2009-07-10

Cobalt is known to be toxic at high concentration, to induce contact dermatosis, and occupational radiation skin damage because of its use in nuclear industry. We investigated the intracellular distribution of cobalt in HaCaT human keratinocytes as a model of skin cells, and its interaction with endogenous trace elements. Direct micro-chemical imaging based on ion beam techniques was applied to determine the quantitative distribution of cobalt in HaCaT cells. In addition, synchrotron radiation X-ray fluorescence microanalysis in tomography mode was performed, for the first time on a single cell, to determine the 3D intracellular distribution of cobalt. Results obtained with these micro-chemical techniques were compared to a more classical method based on cellular fractionation followed by inductively coupled plasma atomic emission spectrometry (ICP-AES) measurements. Cobalt was found to accumulate in the cell nucleus and in perinuclear structures indicating the possible direct interaction with genomic DNA, and nuclear proteins. The perinuclear accumulation in the cytosol suggests that cobalt could be stored in the endoplasmic reticulum or the Golgi apparatus. The multi-elemental analysis revealed that cobalt exposure significantly decreased magnesium and zinc content, with a likely competition of cobalt for magnesium and zinc binding sites in proteins. Overall, these data suggest a multiform toxicity of cobalt related to interactions with genomic DNA and nuclear proteins, and to the alteration of zinc and magnesium homeostasis.

Interlaboratory trial for the measurement of total cobalt in equine urine and plasma by ICP-MS.

PubMed

Popot, Marie-Agnes; Ho, Emmie N M; Stojiljkovic, Natali; Bagilet, Florian; Remy, Pierre; Maciejewski, Pascal; Loup, Benoit; Chan, George H M; Hargrave, Sabine; Arthur, Rick M; Russo, Charlie; White, James; Hincks, Pamela; Pearce, Clive; Ganio, George; Zahra, Paul; Batty, David; Jarrett, Mark; Brooks, Lydia; Prescott, Lise-Anne; Bailly-Chouriberry, Ludovic; Bonnaire, Yves; Wan, Terence S M

2017-09-01

Cobalt is an essential mineral micronutrient and is regularly present in equine nutritional and feed supplements. Therefore, cobalt is naturally present at low concentrations in biological samples. The administration of cobalt chloride is considered to be blood doping and is thus prohibited. To control the misuse of cobalt, it was mandatory to establish an international threshold for cobalt in plasma and/or in urine. To achieve this goal, an international collaboration, consisting of an interlaboratory comparison between 5 laboratories for the urine study and 8 laboratories for the plasma study, has been undertaken. Quantification of cobalt in the biological samples was performed by inductively coupled plasma-mass spectrometry (ICP-MS). Ring tests were based on the analysis of 5 urine samples supplemented at concentrations ranging from 5 up to 500 ng/mL and 5 plasma samples spiked at concentrations ranging from 0.5 up to 25 ng/mL. The results obtained from the different laboratories were collected, compiled, and compared to assess the reproducibility and robustness of cobalt quantification measurements. The statistical approach for the ring test for total cobalt in urine was based on the determination of percentage deviations from the calculated means, while robust statistics based on the calculated median were applied to the ring test for total cobalt in plasma. The inter-laboratory comparisons in urine and in plasma were successful so that 97.6% of the urine samples and 97.5% of the plasma samples gave satisfactory results. Threshold values for cobalt in plasma and urine were established from data only obtained by laboratories involved in the ring test. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

The effect of cobalt content in U-700 type alloys on degradation of aluminide coatings

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1985-01-01

The influence of cobalt content in U-700 type alloys on the behavior of aluminide coatings is studied in burner rig cyclic oxidation tests at 1100C. It is determined that aluminide coatings on alloys with higher cobalt offer better oxidation protection than the same coatings on alloys containing less cobalt.

Radioactive cobalt removal from Salem liquid radwaste with cobalt selective media

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Xin; Ren, Zhibo; Zhu, Xiaolin

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

The effects of cobalt on the development, oxidative stress, and apoptosis in zebrafish embryos.

PubMed

Cai, Guiquan; Zhu, Junfeng; Shen, Chao; Cui, Yimin; Du, Jiulin; Chen, Xiaodong

2012-12-01

Metal-on-metal hip arthroplasty has been performed with increasing frequency throughout the world, particularly in younger and more active patients, including women of childbearing age. The potential toxicity of cobalt exposure on fetus is concerned since cobalt ions generated by metal-on-metal bearings can traverse the placenta and be detected in fetal blood and amniotic fluid. This study examined the effects of cobalt exposure on early embryonic development and the mechanisms underlying its toxicity. Zebrafish embryos were exposed to a range of cobalt concentrations (0-100 mg/L) between 1 and 144 h postfertilization. The survival and early development of embryos were not significantly affected by cobalt at concentrations <100 μg/L. However, embryos exposed to higher concentrations (>100 μg/L) displayed reduced survival rates and abnormal development, including delayed hatching, aberrant morphology, retarded growth, and bradycardia. Furthermore, this study examined oxidative stress and apoptosis in embryos exposed to cobalt at concentrations of 0-500 μg/L. Lipid peroxidation levels were increased in cobalt-treated embryos at concentrations of 100 and 500 μg/L. The mRNA levels of catalase, superoxide dismutase 2, p53, caspase-3, and caspase-9 genes were upregulated in a dose-dependent manner. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays also revealed abnormal apoptotic signals in the brain, trunk, and tail when treated with 500 μg/L cobalt. These data suggest that oxidative stress and apoptosis are associated with cobalt toxicity in zebrafish embryos.

Enhanced activity of gold-supported cobalt oxide for the electrochemical evolution of oxygen.

PubMed

Yeo, Boon Siang; Bell, Alexis T

2011-04-13

Scanning electron microscopy, linear sweep voltammetry, chronoamperometry, and in situ surface-enhanced Raman spectroscopy were used to investigate the electrochemical oxygen evolution reaction (OER) occurring on cobalt oxide films deposited on Au and other metal substrates. All experiments were carried out in 0.1 M KOH. A remarkable finding is that the turnover frequency for the OER exhibited by ∼0.4 ML of cobalt oxide deposited on Au is 40 times higher than that of bulk cobalt oxide. The activity of small amounts of cobalt oxide deposited on Pt, Pd, Cu, and Co decreased monotonically in the order Au > Pt > Pd > Cu > Co, paralleling the decreasing electronegativity of the substrate metal. Another notable finding is that the OER turnover frequency for ∼0.4 ML of cobalt oxide deposited on Au is nearly three times higher than that for bulk Ir. Raman spectroscopy revealed that the as-deposited cobalt oxide is present as Co(3)O(4) but undergoes progressive oxidation to CoO(OH) with increasing anodic potential. The higher OER activity of cobalt oxide deposited on Au is attributed to an increase in fraction of the Co sites present as Co(IV) cations, a state of cobalt believed to be essential for OER to occur. A hypothesis for how Co(IV) cations contribute to OER is proposed and discussed. © 2011 American Chemical Society

Potential for cobalt recovery from lateritic ores in Europe

NASA Astrophysics Data System (ADS)

Herrington, R.

2012-04-01

Cobalt is one of the 'critical metals' identified under the EU Raw Materials Initiative. Annually the global mine production of cobalt is around 55,000 tonnes,with Europe's industries consuming around 30% of that figure. Currently Europe produces around 27 tonnes of cobalt from mines in Finland although new capacity is planned. Co-bearing nickel laterite ores being mined in Greece, Macedonia and Kosovo where the cobalt is currently not being recovered (ores have typical analyses of 0.055% Co and >1% Ni,). These ores are currently treated directly in pyrometallurgical plants to recover the contained nickel and this process means there is no separate cobalt product produced. Hydrometallurgical treatment of mineralogically suitable laterite ores can recover the cobalt; for example Cuba recovers 3,500 tonnes of cobalt from its laterite mining operations, which are of a similar scale to the current European operations. Implementation of hydrometallurgical techniques is in its infancy in Europe with one deposit in Turkey planning to use atmospheric heap leaching to recover nickel and copper from oxide-dominated ores. More widespread implementation of these methods to mineralogically suitable ore types could unlock the highly significant undeveloped resources (with metal contents >0.04% Co and >1% Ni), which have been defined throughout the Balkans eastwards into Turkey. At a conservative estimate, this region has the potential to supply up to 30% of the EU cobalt requirements.

Intra- and interparticle magnetism of cobalt-doped iron-oxide nanoparticles encapsulated in a synthetic ferritin cage

NASA Astrophysics Data System (ADS)

Skoropata, E.; Desautels, R. D.; Falvo, E.; Ceci, P.; Kasyutich, O.; Freeland, J. W.; van Lierop, J.

2014-11-01

We present an in-depth examination of the composition and magnetism of cobalt (Co2 +)-doped iron-oxide nanoparticles encapsulated in Pyrococcus furiosus ferritin shells. We show that the Co2 + dopant ions were incorporated into the γ -Fe2O3/Fe3O4 core, with small paramagnetic-like clusters likely residing on the surface of the nanoparticle that were observed for all cobalt-doped samples. In addition, element-specific characterization using Mössbauer spectroscopy and polarized x-ray absorption indicated that Co2 + was incorporated exclusively into the octahedral B sites of the spinel-oxide nanoparticle. Comparable superparamagnetic blocking temperatures, coercivities, and effective anisotropies were obtained for 7%, 10%, and 12% cobalt-doped nanoparticles, and were only slightly reduced for 3% cobalt, indicating a strong effect of cobalt incorporation, with a lesser effect of cobalt content. Due to the regular particle size and separation that result from the use of the ferritin cage, a comparison of the effects of interparticle interactions on the disordered assembly of nanoparticles was also obtained that indicated significantly different behaviors between undoped and cobalt-doped nanoparticles.

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

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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

2017-01-27

Magnetoferritin (M-HFn) is a biomimetic magnetic nanoparticle with a human heavy-chain ferritin (HFn) shell, trapping a magnetite (Fe 3 O 4 ) core that has inherited peroxidase-like activity. In this study, cobalt-doped M-HFn nanoparticles (M-HFn-Co x Fe 3-x O 4 ) 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.

Temperature dependent viscosity of cobalt ferrite / ethylene glycol ferrofluids

NASA Astrophysics Data System (ADS)

Kharat, Prashant B.; Somvanshi, Sandeep B.; Kounsalye, Jitendra S.; Deshmukh, Suraj S.; Khirade, Pankaj P.; Jadhav, K. M.

2018-04-01

In the present work, cobalt ferrite / ethylene glycol ferrofluid is prepared in 0 to 1 (in the step of 0.2) volume fraction of cobalt ferrite nanoparticles synthesized by co-precipitation method. The XRD results confirmed the formation of single phase spinel structure. The Raman spectra have been deconvoluted into individual Lorentzian peaks. Cobalt ferrite has cubic spinel structure with Fd3m space group. FT-IR spectra consist of two major absorption bands, first at about 586 cm-1 (υ1) and second at about 392 cm-1 (υ2). These absorption bands confirm the formation of spinel-structured cobalt ferrite. Brookfield DV-III viscometer and programmable temperature-controlled bath was used to study the relationship between viscosity and temperature. Viscosity behavior with respect to temperature has been studied and it is revealed that the viscosity of cobalt ferrite / ethylene glycol ferrofluids increases with an increase in volume fraction of cobalt ferrite. The viscosity of the present ferrofluid was found to decrease with increase in temperature.

Open-Loop Performance of COBALT Precision Landing Payload on a Commercial Sub-Orbital Rocket

NASA Technical Reports Server (NTRS)

Restrepo, Carolina I.; Carson, John M., III; Amzajerdian, Farzin; Seubert, Carl R.; Lovelace, Ronney S.; McCarthy, Megan M.; Tse, Teming; Stelling, Richard; Collins, Steven M.

2018-01-01

An open-loop flight test campaign of the NASA COBALT (CoOperative Blending of Autonomous Landing Technologies) platform was conducted onboard the Masten Xodiac suborbital rocket testbed. The COBALT platform integrates NASA Guidance, Navigation and Control (GN&C) sensing technologies for autonomous, precise soft landing, including the Navigation Doppler Lidar (NDL) velocity and range sensor and the Lander Vision System (LVS) Terrain Relative Navigation (TRN) system. A specialized navigation filter running onboard COBALT fuses the NDL and LVS data in real time to produce a navigation solution that is independent of GPS and suitable for future, autonomous, planetary, landing systems. COBALT was a passive payload during the open loop tests. COBALT's sensors were actively taking data and processing it in real time, but the Xodiac rocket flew with its own GPS-navigation system as a risk reduction activity in the maturation of the technologies towards space flight. A future closed-loop test campaign is planned where the COBALT navigation solution will be used to fly its host vehicle.

Effects of cobalt in nickel-base superalloys

NASA Technical Reports Server (NTRS)

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

1983-01-01

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

Cobalt mineral exploration and supply from 1995 through 2013

USGS Publications Warehouse

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 Australasia. Chinese companies are increasingly becoming involved in copper and cobalt exploration and mining in Congo (Kinshasa) and Zambia as well as nickel, copper, and other mining in Australia and the South Pacific. Between 2009 and 2013, mines with a cumulative capacity of more than 100,000 metric tons per year of cobalt were proposed to come into production if all sites came into production as scheduled. This additional capacity corresponds to 175 percent of the 2008 global refinery production level. About 45 percent of this cobalt would be from primary nickel deposits, about 32 percent from primary copper deposits, and about 21 percent from primary cobalt deposits. By 2013, about 40 percent of new capacity was expected to come from the African Copperbelt; 38 percent, from Australia and the South Pacific countries of Philippines, Indonesia, New Caledonia, and Papua New Guinea; 11 percent, from other African countries; 5 percent, from North America; and 6 percent, from other areas.

Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support

NASA Technical Reports Server (NTRS)

Klettlinger, Jennifer Lindsey Suder

2012-01-01

The objective of this study was to evaluate the effect of titanium oxide, lanthanum oxide, and zirconium oxide on alumina supported cobalt catalysts. The hypothesis was that the presence of lanthanum oxide, titanium oxide, and zirconium oxide would reduce the interaction between cobalt and the alumina support. This was of interest because an optimized weakened interaction could lead to the most advantageous cobalt dispersion, particle size, and reducibility. The presence of these oxides on the support were investigated using a wide range of characterization techniques such as SEM, nitrogen adsorption, x-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed reduction after reduction (TPR-AR), and hydrogen chemisorptions/pulse reoxidation. Results indicated that both La2O3 and TiO2 doped supports facilitated the reduction of cobalt oxide species in reference to pure alumina supported cobalt catalysts, however further investigation is needed to determine the effect of ZrO2 on the reduction profile. Results showed an increased corrected cluster size for all three doped supported catalysts in comparison to their reference catalysts. The increase in reduction and an increase in the cluster size led to the conclusion that the support-metal interaction weakened by the addition of TiO2 and La2O3. It is also likely that the interaction decreased upon presence of ZrO2 on the alumina, but further research is necessary. Preliminary results have indicated that the alumina-supported catalysts with titanium oxide and lanthanum oxide present are of interest because of the weakened cobalt support interaction. These catalysts showed an increased extent of reduction, therefore more metallic cobalt is present on the support. However, whether or not there is more cobalt available to participate in the Fischer-Tropsch synthesis reaction (cobalt surface atoms) depends also on the cluster size. On one hand, increasing cluster size alone tends to decrease the active site density; on the other hand, by increasing the size of the cobalt clusters, there is less likelihood of forming oxidized cobalt complexes (cobalt aluminate) during Fischer-Tropsch synthesis. Thus, from the standpoint of stability, improving the extent of reduction while increasing the particle size slightly may be beneficial for maintaining the sites, even if there is a slight decrease in overall initial active site density.

Mineral resource of the month: cobalt

USGS Publications Warehouse

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.

Formation and Release of Cobalt(II) Sorption and Precipitation Products in Aging Kaolinite-Water Slurries.

PubMed

Thompson; Parks; Brown

2000-02-15

The uptake and release behavior of cobalt(II) was studied over thousands of hours in CO(2)-free aqueous suspensions of kaolinite under three pairs of total cobalt concentration (Co(T)) and near-neutral pH (7.5-7.8) conditions. Dissolved cobalt, aluminum, and silicon concentrations were monitored by ICPMS, and cobalt-containing products were identified by EXAFS spectroscopy. In each uptake experiment, cobalt sorbed to kaolinite as a mixture of surface-adsorbed monomers or polymers and hydrotalcite-like precipitates of the approximate composition Co(x)Al(OH)(2x+2)(A(n-))(1/n), where 2

Loss of hypoxia-inducible factor 2 alpha in the lung alveolar epithelium of mice leads to enhanced eosinophilic inflammation in cobalt-induced lung injury.

PubMed

Proper, Steven P; Saini, Yogesh; Greenwood, Krista K; Bramble, Lori A; Downing, Nathaniel J; Harkema, Jack R; Lapres, John J

2014-02-01

Hard metal lung disease (HMLD) is an occupational lung disease specific to inhalation of cobalt-containing particles whose mechanism is largely unknown. Cobalt is a known hypoxia mimic and stabilizer of the alpha subunits of hypoxia-inducible factors (HIFs). Previous work revealed that though HIF1α contrib utes to cobalt toxicity in vitro, loss of HIF1α in the alveolar epithelial cells does not provide in vivo protection from cobalt-induced lung inflammation. HIF1α and HIF2α show unique tissue expression profiles, and HIF2α is known to be the predominant HIF mRNA isoform in the adult lung. Thus, if HIF2α activation by cobalt contributes to pathophysiology of HMLD, we hypothesized that loss of HIF2α in lung epithelium would provide protection from cobalt-induced inflammation. Mice with HIF2α-deficiency in Club and alveolar type II epithelial cells (ATIIs) (HIF2α(Δ/Δ)) were exposed to cobalt (60 µg/day) or saline using a subacute occupational exposure model. Bronchoalveolar lavage cellularity, cytokines, qRT-PCR, and histopathology were analyzed. Results show that loss of HIF2α leads to enhanced eosinophilic inflammation and increased goblet cell metaplasia. Additionally, control mice demonstrated a mild recovery from cobalt-induced lung injury compared with HIF2α(Δ/Δ) mice, suggesting a role for epithelial HIF2α in repair mechanisms. The expression of important cytokines, such as interleukin (IL)-5 and IL-10, displayed significant differences following cobalt exposure when HIF2α(Δ/Δ) and control mice were compared. In summary, our data suggest that although loss of HIF2α does not afford protection from cobalt-induced lung inflammation, epithelial HIF2α signaling does play an important role in modulating the inflammatory and repair response in the lung.

Charge transfer complexes of adenosine-5‧-monophosphate and cytidine-5‧-monophosphate with water-soluble cobalt(II) Schiff base complexes in aqueous solution

NASA Astrophysics Data System (ADS)

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2006-01-01

Water-soluble cobalt(II) tetradentate Schiff base complexes have been shown to form charge transfer (CT) complexes with a series of nucleoside monophosphates including adenosine-5‧-monophosphate (AMP) and cytidine-5‧-monophosphate (CMP). The investigated water-soluble cobalt(II) Schiff base complexes are (i) disodium[{bis(5-sulfo-salicylaldehyde)-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-salophen)] (1); (ii) disodium[{bis(5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-sal-4,5-dmophen)] (2) and (iii) disodium[{bis(4-methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-4-meosal-4,5-dmophen)] (3). The formation constant and thermodynamic parameters for charge transfer complex formation of water-soluble cobalt(II) Schiff base complexes with nucleoside monophosphates were determined spectrophotometrically in aqueous solution at constant ionic strength (I = 0.2 mol dm-3 KNO3) under physiological condition (pH 7.0) and at various temperatures between 288 and 308 K. The stoichiometry has been found to be 1:1 (water-soluble cobalt(II) Schiff base complex: nucleoside monophosphate) in each case. Our spectroscopic and thermodynamic results show that the interaction of water-soluble cobalt(II) Schiff base complexes with the investigated nucleoside monophosphates occurs mainly through the phosphate group. The trend of the interaction according to the cobalt(II) Schiff base complexes due to electronic and steric factors is as follows: Na2[Co(SO3-salophen)] > Na2[Co(SO3-sal-4,5-dmophen)] > Na2[Co(SO3-4-meosal-4,5-dmophen)]. Also the trend of the interaction of a given cobalt(II) Schiff base complex according to the nucleoside monophosphate is as follows: CMP > AMP.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE... the production of tungsten or cobalt at secondary tungsten and cobalt facilities processing tungsten...

Reduction of Late In-Stent Stenosis in a Porcine Coronary Artery Model by Cobalt Chromium Stents with a Nanocoat of Polyphosphazene (Polyzene-F)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stampfl, Ulrike; Sommer, Christof-Matthias; Thierjung, Heidi

2008-11-15

The purpose of this study was to investigate the potential of nanoscale coating with the highly biocompatible polymer Polyzene-F (PZF), in combination with cobalt chromium and stainless steel stents, to reduce in-stent stenosis, thrombogenicity, and vessel wall injury and inflammation. One bare cobalt chromium, PZF-nanocoated stainless steel or PZF-nanocoated cobalt chromium stent was implanted in right coronary artery of 30 mini-pigs (4- or 12-week follow-up). Primary study end points were in-stent stenosis and thrombogenicity. Secondary study end points were vessel wall injury and inflammation as evaluated by microscopy and a new immunoreactivity score applying C-reactive protein (CRP), tumor-necrosis factor alphamore » (TNF{alpha}), and TGF{beta}. At 12 weeks, angiography showed a significantly lower average loss in lumen diameter (2.1% {+-} 3.05%) in PZF-nanocoated cobalt chromium stents compared with stents in the other groups (9.73% {+-} 4.93% for bare cobalt chromium stents and 9.71% {+-} 7% for PZF-nanocoated stainless steel stents; p = 0.04), which was confirmed at microscopy (neointima 40.7 {+-} 16 {mu}m in PZF-nanocoated cobalt chromium stents, 74.7 {+-} 57.6 {mu}m in bare cobalt chromium stents, and 141.5 {+-} 109 {mu}m in PZF-nanocoated stainless steel stents; p = 0.04). Injury and inflammation scores were low in all stents and were without significant differences. PZF-nanocoated cobalt chromium stents provided the highest efficacy in reducing in-stent stenosis at long-term follow-up. The PZF nanocoat proved to be biocompatible with respect to thromboresistance and inflammation. Our data suggest that its combination with cobalt chromium stents might provide an interesting passive stent platform.« less

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE... production of nickel or cobalt by primary nickel and cobalt facilities processing ore concentrate raw...

Low-solubility particles and a Trojan-horse type mechanism of toxicity: the case of cobalt oxide on human lung cells

PubMed Central

2014-01-01

Background The mechanisms of toxicity of metal oxide particles towards lung cells are far from being understood. In particular, the relative contribution of intracellular particulate versus solubilized fractions is rarely considered as it is very challenging to assess, especially for low-solubility particles such as cobalt oxide (Co3O4). Methods This study was possible owing to two highly sensitive, independent, analytical techniques, based on single-cell analysis, using ion beam microanalysis, and on bulk analysis of cell lysates, using mass spectrometry. Results Our study shows that cobalt oxide particles, of very low solubility in the culture medium, are readily incorporated by BEAS-2B human lung cells through endocytosis via the clathrin-dependent pathway. They are partially solubilized at low pH within lysosomes, leading to cobalt ions release. Solubilized cobalt was detected within the cytoplasm and the nucleus. As expected from these low-solubility particles, the intracellular solubilized cobalt content is small compared with the intracellular particulate cobalt content, in the parts-per-thousand range or below. However, we were able to demonstrate that this minute fraction of intracellular solubilized cobalt is responsible for the overall toxicity. Conclusions Cobalt oxide particles are readily internalized by pulmonary cells via the endo-lysosomal pathway and can lead, through a Trojan-horse mechanism, to intracellular release of toxic metal ions over long periods of time, involving specific toxicity. PMID:24669904

Design, Fabrication, Characterization and Modeling of Integrated Functional Materials

DTIC Science & Technology

2009-10-01

cobalt ferrite (CoFe2O4) nanoparticles dispersed in a low-loss commercial polymer matrix obtained from Rogers Corporation. 2 mmol of Cobalt (II...oleylamine and 20 ml benzyl ether were added to the Iron (III) acetylacetonate and Cobalt (II) acetylacetonate mixture. The mixture was stirred...microwave applications Multiferroic bilayers of Cobalt Ferrite and PZT: The objective of this project is to fabricate bilayers of ferroelectric

Investigation of Co, Ni and Fe Doped II-VI Chalcogenides

DTIC Science & Technology

2013-01-04

dopants to the Fe ions. Figure 4. Cobalt doped ZnSe (7×3.1×50 mm3) samples after annealing for 7 days at 950C. A B 8 Approved for public...distribution unlimited. 4.2 Cobalt doped samples ........................................................................................................77...curve for the deposition monitor used for cobalt deposition during magnetron spattering at 1000 nm; B) percentage transmission of a cobalt thin film

Exfoliation and Reassembly of Cobalt Oxide Nanosheets into a Reversible Lithium-Ion Battery Cathode

DTIC Science & Technology

2012-01-01

REPORT Exfoliation and Reassembly of Cobalt Oxide Nanosheets into a Reversible Lithium-Ion Battery Cathode 14. ABSTRACT 16. SECURITY CLASSIFICATION OF...battery fabrication, cobalt oxide Owen C. Compton, Ali Abouimrane, Zhi An, Marc J. Palmeri, L. Catherine Brinson, Khalil Amine, SonBinh T. Nguyen...Exfoliation and Reassembly of Cobalt Oxide Nanosheets into a Reversible Lithium-Ion Battery Cathode Report Title ABSTRACT An exfoliation–reassembly

Cyanide speciation at four gold leach operations undergoing remediation.

PubMed

Johnson, Craig A; Grimes, David J; Leinz, Reinhard W; Rye, Robert O

2008-02-15

Analyses have been made of 81 effluents from four gold leach operations in various stages of remediation to identify the most -persistent cyanide species. Total cyanide and weak acid-dissociable (WAD) cyanide were measured using improved methods, and metals known to form stable cyanocomplexes were also measured. Typically, total cyanide greatly exceeded WAD indicating that cyanide was predominantly in strong cyanometallic complexes. Iron was generally too low to accommodate the strongly complexed cyanide as Fe(CN)6s3- or Fe(CN)6(4-), but cobalt was abundant enough to implicate Co(CN)6(3-) or its dissociation products (Co(CN)(6-x)(H2O)x((3-x)-)). Supporting evidenceforcobalt-cyanide complexationwas found in tight correlations between cobalt and cyanide in some sample suites. Also, abundant free cyanide was produced upon UV illumination. Iron and cobalt cyanocomplexes both photodissociate; however, the iron concentration was insufficient to have carried the liberated cyanide, while the cobalt concentration was sufficient. Cobalt cyanocomplexes have not previously been recognized in cyanidation wastes. Their identification atfour separate operations, which had treated ores that were not especially rich in cobalt, suggests that cobalt complexation may be a common source of cyanide persistence. There is a need for more information on the importance and behavior of cobalt cyanocomplexes in ore-processing wastes at gold mines.

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

PubMed Central

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

2013-01-01

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. PMID:24380018

[Evaluation of bond strength between low fusing porcelain with goldplated cobalt-chromium alloys].

PubMed

Guo, Jing; Zhu, Jia; Zhu, Hong-shui

2014-02-01

To evaluate the bond strength of Vita OMEGA 900 low fusing porcelain fused with the goldplated Wirobond cobalt-chrome metalt ceramic alloy. Low fusing porcelain was fused with the cobalt-chromium alloy strips(group A) and the goldplated cobalt-chromium alloy strips(group B) respectively according to ISO9693 (A:8,B:10). 8 specimens of each group were submitted to three point bending test. Two more test pieces fused with gold plated cobalt-chromium alloys were made (group B'). One test piece of both group B and group B' were observed under scanning electron microscope (SEM) randomly. The data was analyzed with SPSS 16.0 software package. The bond strength (MPa) of group A and group B was 29.92±4.28 and 28.20±5.21, respectively (P>0.05), both higher than 25 MPa required by ISO9693. SEM showed that Vita OMEGA 900 low fusing porcelain and the goldplated Wirobond cobalt-chrome metalt ceramic alloy combined together closely without cracks. Much gold was fused to the cobalt-chrome alloy surface of breaking porcelain specimen after testing. Vita OMEGA 900 low fusing porcelain can match with the goldplated Wirobond cobalt-chrome metalt ceramic alloy. Supported by Foundation of Education Department of Jiangxi Province (GJJ10367).

Spectrophotometric determination of cobalt in horse urine using 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]aniline as chromogenic reagent

NASA Astrophysics Data System (ADS)

Septia Rinda, Arfidyaninggar; Uraisin, Kanchana; Sabarudin, Akhmad; Nacapricha, Duangjai; Wilairat, Prapin

2018-01-01

Cobalt has been reported for being abused as an illegal doping agent due to its ability as an erythropoiesis-stimulating agent for enhancing performance in racehorses. Since 2015, cobalt is listed as a prohibited substance by the International Federation of Horseracing Authorities (IFHA) with a urinary threshold of 0.1 μg cobalt per mL urine. To prevent the misuse of cobalt in racehorse, a simple method for detection of cobalt is desirable. In this work, the detection of cobalt is based on the spectrometric detection of the complex formation between cobalt(II) and 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]aniline at pH 4. The absorbance of the complex is monitored at 602 nm. The metal:ligand ratio of the complex is 1:2. The calibration graph was linear in the range of 0 - 2.5 μM {Absorbance = (0.0825 ± 0.0013)[Co2+] + (0.0406 ± 0.0003), r2 = 0.999} and the detection limit (3 SD of intercept)/slope) was 0.044 μM. The proposed method has been successfully applied to horse urine samples with the recoveries in the range 91 - 98%.

Nickel and cobalt release from jewellery and metal clothing items in Korea.

PubMed

Cheong, Seung Hyun; Choi, You Won; Choi, Hae Young; Byun, Ji Yeon

2014-01-01

In Korea, the prevalence of nickel allergy has shown a sharply increasing trend. Cobalt contact allergy is often associated with concomitant reactions to nickel, and is more common in Korea than in western countries. The aim of the present study was to investigate the prevalence of items that release nickel and cobalt on the Korean market. A total of 471 items that included 193 branded jewellery, 202 non-branded jewellery and 76 metal clothing items were sampled and studied with a dimethylglyoxime (DMG) test and a cobalt spot test to detect nickel and cobalt release, respectively. Nickel release was detected in 47.8% of the tested items. The positive rates in the DMG test were 12.4% for the branded jewellery, 70.8% for the non-branded jewellery, and 76.3% for the metal clothing items. Cobalt release was found in 6.2% of items. Among the types of jewellery, belts and hair pins showed higher positive rates in both the DMG test and the cobalt spot test. Our study shows that the prevalence of items that release nickel or cobalt among jewellery and metal clothing items is high in Korea. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Association between cobalt allergy and dermatitis caused by leather articles--a questionnaire study.

PubMed

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 < 0.001), no association was found between 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.

Monolithic cobalt-doped carbon aerogel for efficient catalytic activation of peroxymonosulfate in water.

PubMed

Hu, Peidong; Long, Mingce; Bai, Xue; Wang, Cheng; Cai, Caiyun; Fu, Jiajun; Zhou, Baoxue; Zhou, Yongfeng

2017-06-15

As an emerging carbonaceous material, carbon aerogels (CAs) display a great potential in environmental cleanup. In this study, a macroscopic three-dimensional monolithic cobalt-doped carbon aerogel was developed by co-condensation of graphene oxide sheets and resorcinol-formaldehyde resin in the presence of cobalt ions, followed by lyophilization, carbonization and thermal treatment in air. Cobalt ions were introduced as a polymerization catalyst to bridge the organogel framework, and finally cobalt species were retained as both metallic cobalt and Co 3 O 4 , wrapped by graphitized carbon layers. The material obtained after a thermal treatment in air (CoCA-A) possesses larger BET specific surface area and pore volume, better hydrophilicity and lower leaching of cobalt ions than that without the post-treatment (CoCA). Despite of a lower loading of cobalt content and a larger mass transfer resistance than traditional powder catalysts, CoCA-A can efficiently eliminate organic contaminants by activation of peroxymonosulfate with a low activation energy. CoCA-A can float beneath the surface of aqueous solution and can be taken out completely without any changes in morphology. The monolith is promising to be developed into an alternative water purification technology due to the easily separable feature. Copyright © 2017 Elsevier B.V. All rights reserved.

Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds

NASA Technical Reports Server (NTRS)

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.

Evaluation of nickel and cobalt release from mobile phone devices used in Brazil.

PubMed

Hafner, Mariana de Figueiredo Silva; Chen, Jessica Chia Sin; Lazzarini, Rosana

2018-01-01

Nickel and cobalt are often responsible for metal-induced allergic contact dermatitis. With the increasing use of cell phones, we observed an increase in cases reports on telephone-related allergic contact dermatitis. The present study evaluated nickel and cobalt release from mobile phones used in Brazil. We evaluated devices of 6 brands and 20 different models using nickel and cobalt allergy spot tests. Of the 20 models, 64.7% tested positive for nickel, with 41.1% positive results for the charger input and 23.5% for other tested areas. None of them was positive for cobalt. Nickel release was more common in older models.

Pulsed Laser Synthesized Magnetic Cobalt Oxide Nanoparticles for Biomedical Applications

NASA Astrophysics Data System (ADS)

Bhatta, Hari; Gupta, Ram; Ghosh, Kartik; Kahol, Pawan; Delong, Robert; Wanekawa, Adam

2011-03-01

Nanomaterials research has become a major attraction in the field of advanced materials research in the area of Physics, Chemistry, and Materials Science. Biocompatible and chemically stable magnetic metal oxide nanoparticles have biomedical applications that includes drug delivery, cell and DNA separation, gene cloning, magnetic resonance imaging (MRI). This research is aimed at the fabrication of magnetic cobalt oxide nanoparticles using a safe, cost effective, and easy to handle technique that is capable of producing nanoparticles free of any contamination. Cobalt oxide nanoparticles have been synthesized at room temperature using cobalt foil by pulsed laser ablation technique. These cobalt oxide nanoparticles were characterized using UV-Visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and dynamic laser light scattering (DLLS). The magnetic cobalt oxides nanoparticles were stabilized in glucose solutions of various concentrations in deionized water. The presence of UV-Vis absorption peak at 270 nm validates the nature of cobalt oxide nanoparticles. The DLLS size distributions of nanoparticles are in the range of 110 to 300 nm, which further confirms the presence nanoparticles. This work is partially supported by National Science Foundation (DMR- 0907037).

Electrochemical Impedance Spectroscopy and Corrosion Behavior of Co/CeO2 Nanocomposite Coatings in Simulating Body Fluid Solution

NASA Astrophysics Data System (ADS)

Benea, Lidia

2013-02-01

A series of Co/CeO2 (25 nm) nanocomposite coating materials by electrodeposition were successfully prepared containing different cerium oxide composition in the cobalt-plating bath. Stainless steel (304L) was used as support material for nanocomposite coatings. The nano-CeO2 is uniformly incorporated into cobalt matrix, and the effect on surface morphologies was identified by scanning electron microscopy with energy-dispersive X-ray analysis. Codeposition of nano-CeO2 particles with cobalt disturbs the regular surface morphology of the cobalt coatings. It should be noted that the as-prepared Co/CeO2 nanocomposite coatings were found to be much superior in corrosion resistance over those of pure cobalt coatings materials based on a series of electrochemical impedance spectroscopy measurements in simulating body fluid solution. With increase in the nano-CeO2 particles concentration in the cobalt electrolyte, it is observed that the corrosion resistance of Co/CeO2 increases. Co/CeO2 nanocomposite coatings have higher polarization resistance as compared with pure cobalt layers in simulating body fluid solution.

Intolerability of cobalt salt as erythropoietic agent.

PubMed

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. Copyright © 2013 John Wiley & Sons, Ltd.

Cobalt-doping-induced synthesis of ceria nanodisks and their significantly enhanced catalytic activity.

PubMed

Guo, Xiao-Hui; Mao, Chao-Chao; Zhang, Ji; Huang, Jun; Wang, Wa-Nv; Deng, Yong-Hui; Wang, Yao-Yu; Cao, Yong; Huang, Wei-Xin; Yu, Shu-Hong

2012-05-21

High-quality cobalt-doped ceria nanostructures with triangular column, triangular slab, and disklike shapes are synthesized by tuning the doping amount of cobalt nitrate in a facile hydrothermal reaction. The cobalt-doped ceria nanodisks display significantly enhanced catalytic activity in CO oxidation due to exposed highly active crystal planes and the presence of numerous surface defects. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of cobalt on the microstructure of Udimet 700. M.S. Thesis Final Report

NASA Technical Reports Server (NTRS)

Engel, M. A.

1982-01-01

Cobalt, a critical and "strategic" alloying element in many superalloys, was systematically substituted by nickel in experimental alloys Udimet 700 containing 0.1, 4.3, 8.6, 12.8 and the standard 17.0 wt.% cobalt. Electrolytic and chemical extraction techniques, X-ray diffraction, scanning electron and optical microscopy were used for the microstructural studies. The total weight fraction of gamma' was not significantly affected by the cobalt content, although a difference in the size and quantities of the primary and secondary gamma' phases was apparent. The lattice parameters of the gamma' were found to increase with increasing cobalt content while the lattice mismatch between the gamma matrix and gamma' phases decreased. Other significant effects of cobalt on the weight fraction, distribution and formation of the carbide and boride phases as well as the relative stability of the experimental alloys during long-time aging are also discussed.

Friction and wear of plasma-sprayed coatings containing cobalt alloys from 25 deg to 650 deg in air

NASA Technical Reports Server (NTRS)

Sliney, H. E.; Jacobson, T. P.

1979-01-01

Four different compositions of self-lubricating, plasma-sprayed, composite coatings with calcium fluoride dispersed throughout cobalt alloy-silver matrices were evaluated on a friction and wear apparatus. In addition, coatings of the cobalt alloys alone and one coating with a nickel alloy-silver matrix were evaluated for comparison. The wear specimens consisted of two, diametrically opposed, flat rub shoes sliding on the coated, cylindrical surface of a rotating disk. Two of the cobalt composite coatings gave a friction coefficient of about 0.25 and low wear at room temperature, 400 and 650 C. Wear rates were lower than those of the cobalt alloys alone or the nickel alloy composite coating. However, oxidation limited the maximum useful temperature of the cobalt composite coating to about 650 C compared to about 900 C for the nickel composite coating.

Investigation on the structures and magnetic properties of carbon or nitrogen doped cobalt ferrite nanoparticles.

PubMed

Cao, Derang; Pan, Lining; Li, Jianan; Cheng, Xiaohong; Zhao, Zhong; Xu, Jie; Li, Qiang; Wang, Xia; Li, Shandong; Wang, Jianbo; Liu, Qingfang

2018-05-21

Carbon or nitrogen doped cobalt ferrite nanoparticles were synthesized in the air by a facile calcination process. X-ray diffraction, mapping, X-ray photoelectron spectroscopy, and mössbauer spectra results indicate that the nonmetal elements as the interstitial one are doped into cobalt ferrite nanoparticles. The morphologies of doped cobalt ferrite nanoparticles change from near-spherical to irregular cubelike shapes gradually with the increased carbon or nitrogen concentration, and their particles sizes also increase more than 200 nm. Furthermore, the saturation magnetization of carbon doped cobalt ferrite is improved. Although the saturation magnetization of N-doped cobalt ferrite is not enhanced obviously due to the involved hematite, they also do not drop drastically. The results reveal an approach to synthesize large scale ferrite nanoparticles, and improve the magnetic properties of ferrite nanoparticles, and also provide the potential candidates to synthesis co-doped functional magnetic materials.

Unconventional magnetisation texture in graphene/cobalt hybrids

DOE PAGES

Vu, A. D.; Coraux, J.; Chen, G.; ...

2016-04-26

Magnetic domain structure and spin-dependent reflectivity measurements on cobalt thin films intercalated at the graphene/Ir(111) interface are investigated using spin-polarised low-energy electron microscopy. We find that graphene-covered cobalt films have surprising magnetic properties. Vectorial imaging of magnetic domains reveals an unusually gradual thickness-dependent spin reorientation transition, in which magnetisation rotates from out-of-the-film plane to the in-plane direction by less than 10° per cobalt monolayer. During this transition, cobalt films have a meandering spin texture, characterised by a complex, three-dimensional, wavy magnetisation pattern. In addition, spectroscopy measurements suggest that the electronic band structure of the unoccupied states is essentially spin-independent alreadymore » a few electron-Volts above the vacuum level. These properties strikingly differ from those of pristine cobalt films and could open new prospects in surface magnetism.« less

Facile fabrication of cobalt oxalate nanostructures with superior specific capacitance and super-long cycling stability

NASA Astrophysics Data System (ADS)

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.

Cobalt doped CuMnOx catalysts for the preferential oxidation of carbon monoxide

NASA Astrophysics Data System (ADS)

Dey, Subhashish; Dhal, Ganesh Chandra; Mohan, Devendra; Prasad, Ram; Gupta, Rajeev Nayan

2018-05-01

Carbon monoxide (CO) is a poisonous gas, recognized as a silent killer for the 21st century. It is produced from the partial oxidation of carbon containing compounds. The catalytic oxidation of CO receives a huge attention due to its applications in different fields. In the present work, hopcalite (CuMnOx) catalysts were synthesized using a co-precipitation method for CO oxidation purposes. Also, it was doped with the cobalt by varying concentration from 1 to 5wt%. It was observed that the addition of cobalt into the CuMnOx catalyst (by the deposition-precipitation method) improved the catalytic performance for the low-temperature CO oxidation. CuMnOx catalyst doped with 3wt% of cobalt exhibited most active performance and showed the highest activity than other cobalt concentrations. Different analytical tools (i.e. XRD, FTIR, BET, XPS and SEM-EDX) were used to characterize the as-synthesized catalysts. It was expected that the introduction of cobalt will introduce new active sites into the CuMnOx catalyst that are associated with the cobalt nano-particles. The order of calcination strategies based on the activity for cobalt doped CuMnOx catalysts was observed as: Reactive calcinations (RC) > flowing air > stagnant air. Therefore, RC (4.5% CO in air) route can be recommended for the synthesis of highly active catalysts. The catalytic activity of doped CuMnOx catalysts toward CO oxidation shows a correlation among average oxidation number of Mn and the position and the nature of the doped cobalt cation.

Fischer-Tropsch activity for non-promoted cobalt-on-alumina catalysts

DOEpatents

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2001-01-01

Cobalt catalysts, and processes employing these inventive catalysts, for hydrocarbon synthesis. The inventive catalyst comprises cobalt on an alumina support and is not promoted with any noble or near noble metals. In one aspect of the invention, the alumina support preferably includes a dopant in an amount effective for increasing the activity of the inventive catalyst. The dopant is preferably a titanium dopant. In another aspect of the invention, the cobalt catalyst is preferably reduced in the presence of hydrogen at a water vapor partial pressure effective to increase the activity of the cobalt catalyst for hydrocarbon synthesis. The water vapor partial pressure is preferably in the range of from 0 to about 0.1 atmospheres.

Construction of Uniform Cobalt-Based Nanoshells and Its Potential for Improving Li-Ion Battery Performance.

PubMed

Piao, Jun-Yu; Liu, Xiao-Chan; Wu, Jinpeng; Yang, Wanli; Wei, Zengxi; Ma, Jianmin; Duan, Shu-Yi; Lin, Xi-Jie; Xu, Yan-Song; Cao, An-Min; Wan, Li-Jun

2018-06-28

Surface cobalt doping is an effective and economic way to improve the electrochemical performance of cathode materials. Herein, by tuning the precipitation kinetics of Co 2+ , we demonstrate an aqueous-based protocol to grow uniform basic cobaltous carbonate coating layer onto different substrates, and the thickness of the coating layer can be adjusted precisely in nanometer accuracy. Accordingly, by sintering the cobalt-coated LiNi 0.5 Mn 1.5 O 4 cathode materials, an epitaxial cobalt-doped surface layer will be formed, which will act as a protective layer without hindering charge transfer. Consequently, improved battery performance is obtained because of the suppression of interfacial degradation.

Neutron diffraction studies on cobalt substituted BiFeO3

NASA Astrophysics Data System (ADS)

Ray, J.; Biswal, A. K.; Acharya, S.; Babu, P. D.; Siruguri, V.; Vishwakarma, P. N.

2013-02-01

A dilute concentration of single phase Cobalt substituted Bismuth ferrite, BiFe1-XCoXO3; (x=0, 0.02) is prepared by sol-gel auto combustion method. Room temperature neutron diffraction patterns show no change in the crystal and magnetic structure upon cobalt doping. The calculation of magnetic moments shows 3.848 μB for Fe+ and 2.85 μB for Co3+. The cobalt is found to be in intermediate spin state.

Effect of Pressing Parameters on the Structure of Porous Materials Based on Cobalt and Nickel Powders

NASA Astrophysics Data System (ADS)

Shustov, V. S.; Rubtsov, N. M.; Alymov, M. I.; Ankudinov, A. B.; Evstratov, E. V.; Zelensky, V. A.

2018-03-01

Porous materials with a bulk porosity of more than 68% were synthesized by powder metallurgy methods from a cobalt-nickel mixture. The effect of the ratio of nickel and cobalt powders used in the synthesis of this porous material (including cases when either nickel or cobalt alone was applied) and the conditions of their compaction on structural parameters, such as open and closed porosities and pose size, was established.

COBALT FOLLICULITIS

PubMed Central

Sidell, Chester M.; Erickson, J. Gordon; McCleary, Jack E.

1958-01-01

Clinical observations in 60 cases of folliculitis or pronounced activation of acne in patients taking cobalt led to conclusion that the development or aggravation of the dermal lesions were owing to ingestion of the metal. The dermal manifestations abated when use of cobalt was discontinued. Active acne is considered a contraindication to the use of vitamin-iron-mineral supplements containing cobalt. Short courses of antibiotics in addition to regular acne regimen helped shorten the course of the eruption. ImagesFigure 1. PMID:13489508

Structural and magnetic properties of the products of the transformation of ferrihydrite: Effect of cobalt dications

NASA Astrophysics Data System (ADS)

Camacho, K. I.; Pariona, N.; Martinez, A. I.; Baggio-Saitovitch, E.; Herrera-Trejo, M.; Perry, Dale L.

2017-05-01

The effect of cobalt dications on the transformation of 2-line ferrihydrite (2LF) has been studied. The products of the transformation reaction were characterized by X-ray diffraction, Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), magnetometry, and first-order reversal curve (FORC) diagrams. It was found that the concentration of cobalt dications plays an important role on the structural and magnetic properties of the products; i.e., for low cobalt concentrations, cobalt-substituted hematite is formed, while higher concentrations promote the formation of cobalt-substituted magnetite. Structural results revealed that formation of other iron oxide polymorphs is avoided and residual 2LF is always present in the final products. In this way, hematite/2LF and magnetite/2LF nanocomposites were formed. For all the samples, magnetic measurements yielded non-saturated hysteresis loops at a maximum field of 12 kOe. For cobalt-substituted hematite/2LF samples, FORC diagrams revealed the presence of multiple single-domain (SD) components which generate interaction coupling between SD with low and high coercivity. Moreover, for cobalt-substituted magnetite/2LF samples, the FORC diagrams revealed the components of wasp-waist hysteresis loops which consist of mixtures of SD and superparamagnetic particles. One of the goals of the present study is the rigorous, experimental documentation of ferrihydrite/hematite mixtures as a function of reaction conditions for use as analytical standards research.

Hydrometallurgical process for recovery of cobalt from waste cathodic active material generated during manufacturing of lithium ion batteries

NASA Astrophysics Data System (ADS)

Swain, Basudev; Jeong, Jinki; Lee, Jae-chun; Lee, Gae-Ho; Sohn, Jeong-Soo

The paper presents a new leaching-solvent extraction hydrometallurgical process for the recovery of a pure and marketable form of cobalt sulfate solution from waste cathodic active material generated during manufacturing of lithium ion batteries (LIBs). Leaching of the waste was carried out as a function of the leachant H 2SO 4 concentration, temperature, pulp density and reductant H 2O 2 concentration. The 93% of cobalt and 94% of lithium were leached at suitable optimum conditions of pulp density: 100 g L -1, 2 M H 2SO 4, 5 vol.% of H 2O 2, with a leaching time 30 min and a temperature 75 °C. In subsequent the solvent extraction study, 85.42% of the cobalt was recovered using 1.5 M Cyanex 272 as an extractant at an O/A ratio of 1.6 from the leach liquor at pH 5.00. The rest of the cobalt was totally recovered from the raffinate using 0.5 M of Cyanex 272 and an O/A ratio of 1, and a feed pH of 5.35. Then the co-extracted lithium was scrubbed from the cobalt-loaded organic using 0.1 M Na 2CO 3. Finally, the cobalt sulfate solution with a purity 99.99% was obtained from the cobalt-loaded organic by stripping with H 2SO 4.

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

NASA Astrophysics Data System (ADS)

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.

Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation

PubMed Central

Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

2016-01-01

Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs) elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1) and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p<0.05) in inflammation and inflammatory bone loss by LPS co-challenge with Cobalt vs. Cobalt alone was evident, even at high levels of LPS (i.e. levels commiserate with hematogenous levels in fatal sepsis, >500pg/mL). Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (<2pg/mL) from Gram-negative bacteria, seem to have negligible contribution to the danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate associated inflammatory and toxicity-like reactions of specific orthopedic implants. PMID:27467577

Bioremediation of 60Co from simulated spent decontamination solutions.

PubMed

Rashmi, K; Sowjanya, T Naga; Mohan, P Maruthi; Balaji, V; Venkateswaran, G

2004-07-26

Bioremediation of 60Co from simulated spent decontamination solutions by utilizing different biomass of (Neurospora crassa, Trichoderma viridae, Mucor recemosus, Rhizopus chinensis, Penicillium citrinum, Aspergillus niger and, Aspergillus flavus) fungi is reported. Various fungal species were screened to evaluate their potential for removing cobalt from very low concentrations (0.03-0.16 microM) in presence of a high background of iron (9.33 mM) and nickel (0.93 mM) complexed with EDTA (10.3 mM). The different fungal isolates employed in this study showed a pickup of cobalt in the range 8-500 ng/g of dry biomass. The [Fe]/[Co] and [Ni]/[Co] ratios in the solutions before and after exposure to the fungi were also determined. At micromolar level the cobalt pickup by many fungi especially the mutants of N. crassa is seen to be proportional to the initial cobalt concentration taken in the solution. However, R. chinensis exhibits a low but iron concentration dependent cobalt pickup. Prior saturating the fungi with excess of iron during their growth showed the presence of selective cobalt pickup sites. The existence of cobalt specific sorption sites is shown by a model experiment with R. chinensis wherein at a constant cobalt concentration (0.034 microM) and varying iron concentrations so as to yield [Fe/Co]initial ratios in solution of 10, 100, 1000 and 287000 have all yielded a definite Co pickup capacity in the range 8-47 ng/g. The presence of Cr(III)EDTA (3 mM) in solution along with complexed Fe and Ni has not influenced the cobalt removal. The significant feature of this study is that even when cobalt is present in trace level (sub-micromolar) in a matrix of high concentration (millimolar levels) of iron, nickel and chromium, a situation typically encountered in spent decontamination solutions arising from stainless steel based primary systems of nuclear reactors, a number of fungi studied in this work showed a good sensitivity for cobalt pickup. Copyright 2004 Elsevier B.V.

Effects of long-time elevated temperature exposures on hot-isostatically-pressed power-metallurgy Udimet 700 alloys with reduced cobalt contents

NASA Technical Reports Server (NTRS)

Hart, F. H.

1984-01-01

Because almost the entire U.S. consumption of cobalt depends on imports, this metal has been designated "strategic'. The role and effectiveness of cobalt is being evaluated in commercial nickel-base superalloys. Udiment 700 type alloys in which the cobalt content was reduced from the normal 17% down to 12.7%, 8.5%, 4.3%, and 0% were prepared by standard powder metallurgy techniques and hot isostatically pressed into billets. Mechanical testing and microstructural investigations were performed. The mechanical properties of alloys with reduced cobalt contents which were heat-treated identically were equal or better than those of the standard alloy, except that creep rates tended to increase as cobalt was reduced. The effects of long time exposures at 760 C on mechanical properties and at 760 C and 845 C on microstructures were determined. Decreased tensile properties and shorter rupture lives with increased creep rates were observed in alloy modifications. The exposures caused gamma prime particle coarsening and formation of sigma phase in the alloys with higher cobalt contents. Exposure at 845 C also reduced the amount of MC carbides.

Cobalt ion-coordinated self-assembly synthesis of nitrogen-doped ordered mesoporous carbon nanosheets for efficiently catalyzing oxygen reduction.

PubMed

Wang, Haitao; Wang, Wei; Asif, Muhammad; Yu, Yang; Wang, Zhengyun; Wang, Junlei; Liu, Hongfang; Xiao, Junwu

2017-10-19

The design and synthesis of a promising porous carbon-based electrocatalyst with an ordered and uninterrupted porous structure for oxygen reduction reaction (ORR) is still a significant challenge. Herein, an efficient catalyst based on cobalt-embedded nitrogen-doped ordered mesoporous carbon nanosheets (Co/N-OMCNS) is successfully prepared through a two-step procedure (cobalt ion-coordinated self-assembly and carbonization process) using 3-aminophenol as a nitrogen source, cobalt acetate as a cobalt source and Pluronic F127 as a mesoporous template. This work indicates that the formation of a two dimensional nanosheet structure is directly related to the extent of the cobalt ion coordination interaction. Moreover, the critical roles of pyrolysis temperature in nitrogen doping and ORR catalytic activity are also investigated. Benefiting from the high surface area and graphitic degree, high contents of graphitic N and pyridinic N, ordered interconnected mesoporous carbon framework, as well as synergetic interaction between the cobalt nanoparticles and protective nitrogen doped graphitic carbon layer, the resultant optimal catalyst Co/N-OMCNS-800 (pyrolyzed at 800 °C) exhibits comparable ORR catalytic activity to Pt/C, superior tolerance to methanol crossover and stability.

Sensitivity of ambient dose equivalent to the concentration of cobalt impurity present in stainless steel

NASA Astrophysics Data System (ADS)

Shetty, N.; Olsovcova, V.; Versaci, R.

2018-06-01

Stainless steels contain nickel in large amounts (about 8 %) to improve its corrosion and heat resistance. Traces of cobalt are present in nickel, which are hard to separate because of its chemical similarity. Therefore, cobalt content in steel is restricted to a maximum of 2 parts per mille for applications in nuclear industry, as natural cobalt (composed of 100% Co-59) transmutes into highly radioactive Co-60 by absorbing a thermal neutron. Co-60 has a rather long half-life of 5.3 years decaying to stable Ni-60 by emitting 2 gammas of 1.17 MeV and 1.33 MeV during the process. These hard gammas will be mostly responsible for the dose rates seen in the next few tens of years. Therefore, it is important to consider the activation of cobalt in steel and estimate the dose contributed by it. Monte Carlo simulations are performed where stainless steel samples with different cobalt concentrations are irradiated with thermal and epithermal neutrons. The ambient dose equivalent, H*(10), from irradiated samples is found to be linearly proportional to the concentration of cobalt. This paper explains the motivation, the procedure, and the detailed results of the simulations.

Corrosion resistance of sodium sulfate coated cobalt-chromium-aluminum alloys at 900 C, 1000 C, and 1100 C

NASA Technical Reports Server (NTRS)

Santoro, G. J.

1979-01-01

The corrosion of sodium sulfate coated cobalt alloys was measured and the results compared to the cyclic oxidation of alloys with the same composition, and to the hot corrosion of compositionally equivalent nickel-base alloys. Cobalt alloys with sufficient aluminum content to form aluminum containing scales corrode less than their nickel-base counterparts. The cobalt alloys with lower aluminum levels form CoO scales and corrode more than their nickel-base counterparts which form NiO scales.

Raman analysis of cobalt blue pigment in blue and white porcelain: A reassessment.

PubMed

Jiang, Xiaochenyang; Ma, Yanying; Chen, Yue; Li, Yuanqiu; Ma, Qinglin; Zhang, Zhaoxia; Wang, Changsui; Yang, Yimin

2018-02-05

Cobalt blue is a famous pigment in human history. In the past decade it is widely reported that the cobalt aluminate has been detected in ancient ceramics as blue colorant in glaze, yet the acquired Raman spectra are incredibly different from that of synthesised references, necessitating a reassessment of such contradictory scenario with more accurate analytic strategies. In this study, micro-Raman spectroscopy (MRS) and scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) were performed on under-glaze cobalt pigments from one submerged blue and white porcelain shard dated from Wanli reign (1573-1620CE) of Ming dynasty (1365-1644CE) excavated at Nan'ao I shipwreck off the southern coast of China. The micro-structural inspection reveals that the pigment particles have characteristics of small account, tiny size, heterogeneously distribution, and more importantly, been completely enwrapped by well-developed anorthite crystals in the glaze, indicating that the signals recorded in previous publications are probably not from cobalt pigments themselves but from outside thickset anorthite shell. The further spectromicroscopic analyses confirm this presumption when the accurate spectra of cobalt aluminate pigment and surrounding anorthite were obtained separately with precise optical positioning. Accordingly, we reassess and clarify the previous Raman studies dedicated to cobalt blue pigment in ancient ceramics, e.g. cobalt blue in celadon glaze, and in turn demonstrate the superiority and necessity of coupling spectroscopic analysis with corresponding structure observation, especially in the characterization of pigments from complicated physico-chemical environment like antiquities. Thus, this study promotes a better understanding of Raman spectroscopy study of cobalt blue pigments in art and archaeology field. Copyright © 2017 Elsevier B.V. All rights reserved.

Raman analysis of cobalt blue pigment in blue and white porcelain: A reassessment

NASA Astrophysics Data System (ADS)

Jiang, Xiaochenyang; Ma, Yanying; Chen, Yue; Li, Yuanqiu; Ma, Qinglin; Zhang, Zhaoxia; Wang, Changsui; Yang, Yimin

2018-02-01

Cobalt blue is a famous pigment in human history. In the past decade it is widely reported that the cobalt aluminate has been detected in ancient ceramics as blue colorant in glaze, yet the acquired Raman spectra are incredibly different from that of synthesised references, necessitating a reassessment of such contradictory scenario with more accurate analytic strategies. In this study, micro-Raman spectroscopy (MRS) and scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) were performed on under-glaze cobalt pigments from one submerged blue and white porcelain shard dated from Wanli reign (1573-1620 CE) of Ming dynasty (1365-1644 CE) excavated at Nan'ao I shipwreck off the southern coast of China. The micro-structural inspection reveals that the pigment particles have characteristics of small account, tiny size, heterogeneously distribution, and more importantly, been completely enwrapped by well-developed anorthite crystals in the glaze, indicating that the signals recorded in previous publications are probably not from cobalt pigments themselves but from outside thickset anorthite shell. The further spectromicroscopic analyses confirm this presumption when the accurate spectra of cobalt aluminate pigment and surrounding anorthite were obtained separately with precise optical positioning. Accordingly, we reassess and clarify the previous Raman studies dedicated to cobalt blue pigment in ancient ceramics, e.g. cobalt blue in celadon glaze, and in turn demonstrate the superiority and necessity of coupling spectroscopic analysis with corresponding structure observation, especially in the characterization of pigments from complicated physico-chemical environment like antiquities. Thus, this study promotes a better understanding of Raman spectroscopy study of cobalt blue pigments in art and archaeology field.

The mechanical response of a polyetheretherketone femoral knee implant under a deep squatting loading condition.

PubMed

de Ruiter, Lennert; Janssen, Dennis; Briscoe, Adam; Verdonschot, Nico

2017-12-01

The current study was designed to investigate the mechanical response of a polyetheretherketone-on-polyethylene total knee replacement device during a deep squat. Application of this high-demand loading condition can identify weaknesses of the polyetheretherketone relative to cobalt-chromium. This study investigated whether the implant is strong enough for this type of loading, whether cement stresses are considerably changed and whether a polyetheretherketone femoral component is likely to lead to reduced periprosthetic bone loss as compared to a cobalt-chromium component. A finite element model of a total knee arthroplasty subjected to a deep squat loading condition, which was previously published, was adapted with an alternative total knee arthroplasty design made of either polyetheretherketone or cobalt-chromium. The maximum tensile and compressive stresses within the implant and cement mantle were analysed against their yield and fatigue stress levels. The amount of stress shielding within the bone was compared between the polyetheretherketone and cobalt-chromium cases. Relative to its material strength, tensile peak stresses were higher in the cobalt-chromium implant; compressive peak stresses were higher in the polyetheretherketone implant. The stress patterns differed substantially between polyetheretherketone and cobalt-chromium. The tensile stresses in the cement mantle supporting the polyetheretherketone implant were up to 33% lower than with the cobalt-chromium component, but twice as high for compression. Stress shielding was reduced to a median of 1% for the polyetheretherketone implant versus 56% for the cobalt-chromium implant. Both the polyetheretherketone implant and the underlying cement mantle should be able to cope with the stress levels present during a deep squat. Relative to the cobalt-chromium component, stress shielding of the periprosthetic femur was substantially less with a polyetheretherketone femoral component.

Applications of x ray absorption fine structure to the in situ study of the effect of cobalt in nickel hydrous oxide electrodes for fuel cells and rechargeable batteries

NASA Technical Reports Server (NTRS)

Kim, Sunghyun; Tryk, Donald A.; Scherson, Daniel A.; Antonio, Mark R.

1993-01-01

Electronic and structural aspects of composite nickel-cobalt hydrous oxides have been examined in alkaline solutions using in situ X-ray absorption fine structure (XAFS). The results obtained have indicated that cobalt in this material is present as cobaltic ions regardless of the oxidation state of nickel in the lattice. Furthermore, careful analysis of the Co K-edge Extended X-ray absorption fine structure data reveals that the co-electrodeposition procedure generates a single phase, mixed metal hydrous oxide, in which cobaltic ions occupy nickel sites in the NiO2 sheet-like layers and not two intermixed phases each consisting of a single metal hydrous oxide.

Cobalt oxide nanoparticles can enter inside the cells by crossing plasma membranes

PubMed Central

Bossi, Elena; Zanella, Daniele; Gornati, Rosalba; Bernardini, Giovanni

2016-01-01

The ability of nanoparticles (NPs) to be promptly uptaken by the cells makes them both dangerous and useful to human health. It was recently postulated that some NPs might cross the plasma membrane also by a non-endocytotic pathway gaining access to the cytoplasm. To this aim, after having filled mature Xenopus oocytes with Calcein, whose fluorescence is strongly quenched by divalent metal ions, we have exposed them to different cobalt NPs quantifying quenching as evidence of the increase of the concentration of Co2+ released by the NPs that entered into the cytoplasm. We demonstrated that cobalt oxide NPs, but not cobalt nor cobalt oxide NPs that were surrounded by a protein corona, can indeed cross plasma membranes. PMID:26924527

21 CFR 181.25 - Driers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... migrating from food-packaging material shall include: Cobalt caprylate. Cobalt linoleate. Cobalt naphthenate... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Driers. 181.25 Section 181.25 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PRIOR-SANCTIONED FOOD...

The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

NASA Technical Reports Server (NTRS)

Harf, F. H.

1985-01-01

Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

Wrought cobalt- base superalloys

NASA Astrophysics Data System (ADS)

Klarstrom, D. L.

1993-08-01

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

Cobalt toxicity after revision total hip replacement due to fracture of a ceramic head.

PubMed

Pelayo-de Tomás, J M; Novoa-Parra, C; Gómez-Barbero, P

Symptomatic cobalt toxicity from a failed total hip replacement is a rare, but devastating complication. Potential clinical findings include cardiomyopathy, hypothyroidism, skin rash, visual and hearing impairment, polycythaemia, weakness, fatigue, cognitive impairment, and neuropathy. The case is presented of a 74year-old man in whom, after a ceramic-ceramic replacement and two episodes of prosthetic dislocation, it was decided to replace it with a polyethylene-metal total hip arthroplasty (THA). At 6months after the revision he developed symptoms of cobalt toxicity, confirmed by analytical determination (serum cobalt level=651.2μg/L). After removal of the prosthesis, the levels of chromium and cobalt in blood and urine returned to normal, with the patient currently being asymptomatic. It is recommended to use a new ceramic on ceramic bearing at revision, in order to minimise the risk of wear-related cobalt toxicity following breakage of ceramic components. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

Treatment of radioactive liquid waste (Co-60) by sorption on Zeolite Na-A prepared from Iraqi kaolin.

PubMed

Mustafa, Yasmen A; Zaiter, Maysoon J

2011-11-30

Iraqi synthetic zeolite type Na-A has been suggested as ion exchange material to treat cobalt-60 in radioactive liquid waste which came from neutron activation for corrosion products. Batch experiments were conducted to find out the equilibrium isotherm for source sample. The equilibrium isotherm for radioactive cobalt in the source sample showed unfavorable type, while the equilibrium isotherm for the total cobalt (the radioactive and nonradioactive cobalt) in the source sample showed a favorable type. The ability of Na-A zeolite to remove cobalt from wastewater was checked for high cobalt concentration (822 mg/L) in addition to low cobalt concentration in the source sample (0.093 mg/L). A good fitting for the experimental data with Langmuir equilibrium model was observed. Langmuir constant qm which is related to monolayer adsorption capacity for low and high cobalt concentration was determined to be 0.021 and 140 mg/g(zeolite). The effects of important design variables on the zeolite column performance were studied these include initial concentration, flow rate, and bed depth. The experimental results have shown that high sorption capacity can be obtained at high influent concentration, low flow rate, and high bed depth. Higher column performance was obtained at higher bed depth. Thomas model was employed to predict the breakthrough carves for the above variables. A good fitting was observed with correlation coefficients between 0.915 and 0.985. Copyright © 2011 Elsevier B.V. All rights reserved.

Leaching kinetics of cobalt from the scraps of spent aerospace magnetic materials.

PubMed

Zhou, Xuejiao; Chen, Yongli; Yin, Jianguo; Xia, Wentang; Yuan, Xiaoli; Xiang, Xiaoyan

2018-06-01

Based on physicochemical properties of the scraps of spent aerospace magnetic materials, a roasting - magnetic separation followed by sulfuric acid leaching process was proposed to extract cobalt. Roasting was performed at 500 °C to remove organic impurity. Non-magnetic impurities were reduced by magnetic separation and then the raw material was sieved into desired particle sizes. Acid leaching was carried out to extract cobalt from the scraps and experimental parameters included agitation speed, particle size, initial concentration of sulfuric acid and temperature. Agitation speed higher than 300 r/min had a relatively small impact on the cobalt extraction. As the particle size reduced, the content of cobalt in the raw material decreases and the extraction of cobalt by acid leaching increased at first and decreased afterwards. Raising the initial concentration of sulfuric acid and temperature contributed to improve the cobalt extraction and the influence of temperature was more remarkable. SEM image revealed that the spent aerospace magnetic materials mainly existed in the sliced strip flake with a loose surface and porous structure. Under the experimental condition, the leaching rate of cobalt from the scraps in sulfuric acid solution could be expressed as ln(-ln(1 - α)) = lnk + nlnt. The apparent activation energy was found to be 38.33 kJ/mol and it was mainly controlled by the surface chemical reaction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of cobalt content on wear and corrosion behaviors of electrodeposited Ni-Co/WC nano-composite coatings.

PubMed

Amadeh, A; Ebadpour, R

2013-02-01

Metal-ceramic composite coatings are widely used in automotive and aerospace industries as well as micro-electronic systems. Electrodeposition is an economic method for application of these coatings. In this research, nickel-cobalt coatings reinforced by nano WC particles were applied on carbon steel substrate by pulse electrodeposition from modified Watts bath containing different amounts of cobalt sulphate as an additive. Saccharin and sodium dodecyl sulphate (SDS) were also added to electroplating bath as grain refiner and surfactant, respectively. The effect of cobalt content on wear and corrosion behavior of the coatings was investigated. Wear and corrosion properties were assessed by pin-on-disk and potentiodynamic polarization methods, respectively. Phase analysis was performed by X-ray diffraction (XRD) using CuK(alpha) radiation and the worn surfaces were studied by means of Scanning Electron Microscopy (SEM). The results showed that the addition of cobalt improved the wear resistance of the coatings. In the presence of 18 g/L cobalt in electrodeposition bath, the wear rate of the coating decreased to 0.002 mg/m and the coefficient of friction reduced to 0.695 while they were 0.004 mg/m and 0.77 in the absence of cobalt, respectively. This improvement in wear properties can be attributed to the formation of hcp phase in metallic matrix. Meanwhile, the corrosion resistance of the coatings slightly reduced because cobalt is more active metal with respect to nickel.

Organic oxalate as leachant and precipitant for the recovery of valuable metals from spent lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun Liang; Key Laboratory of Resources Chemistry of Nonferrous Metals, Central South University, Ministry of Education of the People's Republic of China; Qiu Keqiang, E-mail: qiuwhs@sohu.com

2012-08-15

Graphical abstract: Display Omitted Highlights: Black-Right-Pointing-Pointer Vacuum pyrolysis as a pretreatment was used to separate cathode material from aluminum foils. Black-Right-Pointing-Pointer Cobalt and lithium can be leached using oxalate while cobalt can be directly precipitated as cobalt oxalate. Black-Right-Pointing-Pointer Cobalt and lithium can be separated efficiently from each other only in the oxalate leaching process. Black-Right-Pointing-Pointer High reaction efficiency of LiCoO{sub 2} was obtained with oxalate. - Abstract: Spent lithium-ion batteries containing lots of strategic resources such as cobalt and lithium are considered as an attractive secondary resource. In this work, an environmentally compatible process based on vacuum pyrolysis, oxalatemore » leaching and precipitation is applied to recover cobalt and lithium from spent lithium-ion batteries. Oxalate is introduced as leaching reagent meanwhile as precipitant which leaches and precipitates cobalt from LiCoO{sub 2} and CoO directly as CoC{sub 2}O{sub 4}{center_dot}2H{sub 2}O with 1.0 M oxalate solution at 80 Degree-Sign C and solid/liquid ratio of 50 g L{sup -1} for 120 min. The reaction efficiency of more than 98% of LiCoO{sub 2} can be achieved and cobalt and lithium can also be separated efficiently during the hydrometallurgical process. The combined process is simple and adequate for the recovery of valuable metals from spent lithium-ion batteries.« less

Cobalt Doping of Semiconducting Boron Carbide Using Cobaltocene

DTIC Science & Technology

2007-03-01

COBALT DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE THESIS Lonnie Carlson, Major...DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE THESIS Presented to the Faculty Department of Engineering Physics Graduate School...DISTRIBUTION UNLIMITED AFIT/GNE/ENP/07-01 COBALT DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE Lonnie

21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a...

21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a...

21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a...

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Cobalt Salts Production...

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

ERIC Educational Resources Information Center

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)

A Highly-Reduced Cobalt Terminal Carbyne: Divergent Metal- and α-Carbon-Centered Reactivity.

PubMed

Mokhtarzadeh, Charles C; Moore, Curtis E; Rheingold, Arnold L; Figueroa, Joshua S

2018-06-15

Reported here is the isolation of a dianionic cobalt terminal carbyne derived from chemical reduction of an encumbering isocyanide ligand. Crystallographic, spectroscopic and computational data reveal that this carbyne possesses a low-valent cobalt center with an extensively-filled d-orbital manifold. This electronic character renders the cobalt center the primary site of nucleophilicity upon reaction with protic substrates and silyl electrophiles. However, reactions with internal alkynes result in [2+2] cycloaddition with the carbyne carbon to form a new C-C bond.

Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC-Co Hard Alloys

NASA Astrophysics Data System (ADS)

Linnik, S. A.; Gaidaichuk, A. V.; Okhotnikov, V. V.

2018-02-01

The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC-Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

Cobalt chloride induces metaphase when topically applied to larvae and pupae of the stingless bee Melipona scutellaris (Hymenoptera, Apidae, Meliponini).

PubMed

Ueira-Vieira, C; Tavares, R R; Morelli, S; Pereira, B B; Silva, R P; Torres-Mariano, A R; Kerr, W E; Bonetti, A M

2013-06-20

In order to optimize preparations of bee metaphases, we tested cobalt chloride, which has been used as a metaphase inducer in other organisms, such as hamsters and fish. Four microliters of 65 mM cobalt chloride aqueous solution was topically applied to larval and pupal stages of the stingless bee Melipona scutellaris. The cerebral ganglion was removed after treatment and prepared for cytogenetic analysis. Identically manipulated untreated individuals were used as controls. The number of metaphases was increased 3-fold in treated individuals compared to controls. The micronucleus test showed no mutagenic effects of cobalt chloride on M. scutellaris cells. We concluded that cobalt chloride is a metaphase-inducing agent in M. scutellaris, thus being useful for cytogenetic analyses.

Preliminary study of a solar selective coating system using black cobalt oxide for high temperature solar collectors

NASA Technical Reports Server (NTRS)

Mcdonald, G.

1980-01-01

Black cobalt oxide coatings (high solar absorptance layer) were deposited on thin layers of silver or gold (low emittance layer) which had been previously deposited on oxidized (diffusion barrier layer) stainless steel substrates. The reflectance properties of these coatings were measured at various thicknesses of cobalt for integrated values of the solar and infrared spectrum. The values of absorptance and emittance were calculated from the measured reflectance values, before and after exposure in air at 650 C for approximately 1000 hours. Absorptance and emittance were interdependent functions of the weight of cobalt oxide. Also, these cobalt oxide/noble metal/oxide diffusion barrier coatings have absorptances greater than 0.90 and emittances of approximately 0.20 even after about 1000 hours at 650 C.

Impedance spectroscopy studies in cobalt ferrite-reduced graphene oxide nanocomposite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supriya, Sweety, E-mail: sweety@iitp.ac.in; Kumar, Sunil, E-mail: sunil.pph13@iitp.ac.in; Kar, Manoranjan, E-mail: mano@iitp.ac.in

2016-05-06

(1-x)Cobalt ferrite-(x)reduced graphene oxidenanocomposites with x=0, 0.1, 0.2 and 0.3 were prepared by the ultrasonic method. The crystal symmetry modification due to reduced graphene oxide and cobalt ferrite interaction has been studied by employing the X-ray diffraction technique. Morphology of the samples was studied by the Field emission scanning electron microscopy (FE-SEM). Study on electrical properties of the cobalt ferrite-reduced graphene oxide nanocomposites explores the possible application of these composites as anode material. Impedance decreases with an increase in frequency as well as temperature, which supports an increase in ac electrical conductivity. The modified Debye relaxation model can explain themore » behavior of impedance in cobalt ferrite-reduced graphene oxide nanocomposites.« less

[Spectroscopic studies on transition metal ions in colored diamonds].

PubMed

Meng, Yu-Fei; Peng, Ming-Sheng

2004-07-01

Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Shibin; College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061; Chang, Xueting, E-mail: xuetingchang@yahoo.cn

Cobalt-doped tungsten oxide mesocrystals with different morphologies have been successfully generated using a solvothermal method with tungsten hexachloride and cobalt chloride salts as precursors. The resulting mesocrystals were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmet-Teller analysis of nitrogen sorptometer, and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of the cobalt-doped tungsten oxide mesocrystals were evaluated on the basis of their ability to degrade methyl orange in an aqueous solution under simulated sunlight irradiation. Results showed that the cobalt doping had obvious effect on the morphologies of the final products, and lenticular and blocky cobalt-dopedmore » tungsten oxide mesocrystals could be obtained with 1.0 wt.% and 2.0 wt.% cobalt doping, respectively. The cobalt-doped tungsten oxides exhibited superior photocatalytic activities to that of the undoped tungsten oxide. - Graphical abstract: Schematic illustrations of the growth of the bundled nanowires, lenticular mesocrystals, and blocky mesocrystals. Highlights: Black-Right-Pointing-Pointer Co-doped W{sub 18}O{sub 49} mesocrystals were synthesized using a solvothermal method. Black-Right-Pointing-Pointer The Co doping has obvious effect on the morphology of the final mesocrystals. Black-Right-Pointing-Pointer The Co-doped W{sub 18}O{sub 49} exhibited superior photocatalytic activity to the undoped W{sub 18}O{sub 49}.« less

COBALT COMPOUNDS AS ANTIDOTES FOR HYDROCYANIC ACID.

PubMed

EVANS, C L

1964-12-01

The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5xLD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5xLD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3xLD50) than for mice (2xLD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered.

Effect of Er doping on the structural and magnetic properties of cobalt-ferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prathapani, Sateesh; Vinitha, M.; Das, D., E-mail: ddse@uohyd.ernet.in

2014-05-07

Nanocrystalline particulates of Er doped cobalt-ferrites CoFe{sub (2−x)}Er{sub x}O{sub 4} (0 ≤ x ≤ 0.04), were synthesized, using sol-gel assisted autocombustion method. Co-, Fe-, and Er- nitrates were the oxidizers, and malic acid served as a fuel and chelating agent. Calcination (400–600 °C for 4 h) of the precursor powders was followed by sintering (1000 °C for 4 h) and structural and magnetic characterization. X-ray diffraction confirmed the formation of single phase of spinel for the compositions x = 0, 0.01, and 0.02; and for higher compositions an additional orthoferrite phase formed along with the spinel phase. Lattice parameter of the doped cobalt-ferrites was higher than that of pure cobalt-ferrite.more » The observed red shift in the doped cobalt-ferrites indicates the presence of induced strain in the cobalt-ferrite matrix due to large size of the Er{sup +3} compared to Fe{sup +3}. Greater than two-fold increase in coercivity (∼66 kA/m for x = 0.02) was observed in doped cobalt-ferrites compared to CoFe{sub 2}O{sub 4} (∼29 kA/m)« less

Open-Loop Flight Testing of COBALT GN&C Technologies for Precise Soft Landing

NASA Technical Reports Server (NTRS)

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

2017-01-01

A terrestrial, open-loop (OL) flight test campaign of the NASA COBALT (CoOperative Blending of Autonomous Landing Technologies) platform was conducted onboard the Masten Xodiac suborbital rocket testbed, with support through the NASA Advanced Exploration Systems (AES), Game Changing Development (GCD), and Flight Opportunities (FO) Programs. The COBALT platform integrates NASA Guidance, Navigation and Control (GN&C) sensing technologies for autonomous, precise soft landing, including the Navigation Doppler Lidar (NDL) velocity and range sensor and the Lander Vision System (LVS) Terrain Relative Navigation (TRN) system. A specialized navigation filter running onboard COBALT fuzes the NDL and LVS data in real time to produce a precise navigation solution that is independent of the Global Positioning System (GPS) and suitable for future, autonomous planetary landing systems. The OL campaign tested COBALT as a passive payload, with COBALT data collection and filter execution, but with the Xodiac vehicle Guidance and Control (G&C) loops closed on a Masten GPS-based navigation solution. The OL test was performed as a risk reduction activity in preparation for an upcoming 2017 closed-loop (CL) flight campaign in which Xodiac G&C will act on the COBALT navigation solution and the GPS-based navigation will serve only as a backup monitor.

New investigations into the genotoxicity of cobalt compounds and their impact on overall assessment of genotoxic risk.

PubMed

Kirkland, David; Brock, Tom; Haddouk, Hasnaà; Hargeaves, Victoria; Lloyd, Melvyn; Mc Garry, Sarah; Proudlock, Raymond; Sarlang, Séverine; Sewald, Katherina; Sire, Guillaume; Sokolowski, Andrea; Ziemann, Christina

2015-10-01

The genotoxicity of cobalt metal and cobalt compounds has been widely studied. Several publications show induction of chromosomal aberrations, micronuclei or DNA damage in mammalian cells in vitro in the absence of S9. Mixed results were seen in gene mutation studies in bacteria and mammalian cells in vitro, and in chromosomal aberration or micronucleus assays in vivo. To resolve these inconsistencies, new studies were performed with soluble and poorly soluble cobalt compounds according to OECD-recommended protocols. Induction of chromosomal damage was confirmed in vitro, but data suggest this may be due to oxidative stress. No biologically significant mutagenic responses were obtained in bacteria, Tk(+/-) or Hprt mutation tests. Negative results were also obtained for chromosomal aberrations (in bone marrow and spermatogonia) and micronuclei at maximum tolerated doses in vivo. Poorly soluble cobalt compounds do not appear to be genotoxic. Soluble compounds do induce some DNA and chromosomal damage in vitro, probably due to reactive oxygen. The absence of chromosome damage in robust GLP studies in vivo suggests that effective protective processes are sufficient to prevent oxidative DNA damage in whole mammals. Overall, there is no evidence of genetic toxicity with relevance for humans of cobalt substances and cobalt metal. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Reactivity of a Cobalt(III)–Hydroperoxo Complex in Electrophilic Reactions

DOE PAGES

Shin, Bongki; Sutherlin, Kyle D.; Ohta, Takehiro; ...

2016-11-15

The reactivity of mononuclear metal-hydroperoxo adducts has fascinated researchers in many areas due to their diverse biological and catalytic processes. In this study, a mononuclear cobalt(III)-peroxo complex bearing a tetradentate macrocyclic ligand, [Co III(Me 3-TPADP)(O 2)] + (Me 3-TPADP = 3,6,9-trimethyl-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane), was prepared by reacting [Co II(Me 3-TPADP)(CH 3CN) 2] 2+ with H 2O 2 in the presence of triethylamine. Upon protonation, the cobalt(III)- peroxo intermediate was converted into a cobalt(III)-hydroperoxo complex, [Co III(Me 3-TPADP)(O 2H)(CH 3CN)] 2+. The mononuclear cobalt(III)-peroxo and -hydroperoxo intermediates were characterized by a variety of physicochemical methods. Results of electrospray ionization mass spectrometry clearly showmore » the transformation of the intermediates: the peak at m/z 339.2 assignable to the cobalt(III)-peroxo species disappears with concomitant growth of the peak at m/z 190.7 corresponding to the cobalt(III)-hydroperoxo complex (with bound CH 3CN). Isotope labeling experiments further support the existence of the cobalt(III)-peroxo and -hydroperoxo complexes. In particular, the O-O bond stretching frequency of the cobalt(III)-hydroperoxo complex was determined to be 851 cm -1 for 16O 2H samples (803 cm -1 for 18O 2H samples) and its Co-O vibrational energy was observed at 571 cm -1 for 16O 2H samples (551 cm -1 for 18O 2H samples; 568 cm -1 for 16O 2 2H samples) by resonance Raman spectroscopy. Reactivity studies performed with the cobalt(III)-peroxo and -hydroperoxo complexes in organic functionalizations reveal that the latter is capable of conducting oxygen atom transfer with an electrophilic character, whereas the former exhibits no oxygen atom transfer reactivity under the same reaction conditions. Alternatively, the cobalt(III)-hydroperoxo complex does not perform hydrogen atom transfer reactions, while analogous low-spin Fe(III)-hydroperoxo complexes are capable of this reactivity. Density function theory calculations indicate that this lack of reactivity is due to the high free energy cost of O-O bond homolysis that would be required to produce the hypothetical Co(IV)-oxo product.« less

Reactivity of a Cobalt(III)–Hydroperoxo Complex in Electrophilic Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Bongki; Sutherlin, Kyle D.; Ohta, Takehiro

The reactivity of mononuclear metal-hydroperoxo adducts has fascinated researchers in many areas due to their diverse biological and catalytic processes. In this study, a mononuclear cobalt(III)-peroxo complex bearing a tetradentate macrocyclic ligand, [Co III(Me 3-TPADP)(O 2)] + (Me 3-TPADP = 3,6,9-trimethyl-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane), was prepared by reacting [Co II(Me 3-TPADP)(CH 3CN) 2] 2+ with H 2O 2 in the presence of triethylamine. Upon protonation, the cobalt(III)- peroxo intermediate was converted into a cobalt(III)-hydroperoxo complex, [Co III(Me 3-TPADP)(O 2H)(CH 3CN)] 2+. The mononuclear cobalt(III)-peroxo and -hydroperoxo intermediates were characterized by a variety of physicochemical methods. Results of electrospray ionization mass spectrometry clearly showmore » the transformation of the intermediates: the peak at m/z 339.2 assignable to the cobalt(III)-peroxo species disappears with concomitant growth of the peak at m/z 190.7 corresponding to the cobalt(III)-hydroperoxo complex (with bound CH 3CN). Isotope labeling experiments further support the existence of the cobalt(III)-peroxo and -hydroperoxo complexes. In particular, the O-O bond stretching frequency of the cobalt(III)-hydroperoxo complex was determined to be 851 cm -1 for 16O 2H samples (803 cm -1 for 18O 2H samples) and its Co-O vibrational energy was observed at 571 cm -1 for 16O 2H samples (551 cm -1 for 18O 2H samples; 568 cm -1 for 16O 2 2H samples) by resonance Raman spectroscopy. Reactivity studies performed with the cobalt(III)-peroxo and -hydroperoxo complexes in organic functionalizations reveal that the latter is capable of conducting oxygen atom transfer with an electrophilic character, whereas the former exhibits no oxygen atom transfer reactivity under the same reaction conditions. Alternatively, the cobalt(III)-hydroperoxo complex does not perform hydrogen atom transfer reactions, while analogous low-spin Fe(III)-hydroperoxo complexes are capable of this reactivity. Density function theory calculations indicate that this lack of reactivity is due to the high free energy cost of O-O bond homolysis that would be required to produce the hypothetical Co(IV)-oxo product.« less

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

2011-12-01

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL -1 of cobalt(II) and optimum concentration range was 5-12.5 μg mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 μg cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 μg cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

Osseointegration and biocompatibility of different metal implants - a comparative experimental investigation in sheep

PubMed Central

2012-01-01

Background In the present study, 4 different metallic implant materials, either partly coated or polished, were tested for their osseointegration and biocompatibility in a pelvic implantation model in sheep. Methods Materials to be evaluated were: Cobalt-Chrome (CC), Cobalt-Chrome/Titanium coating (CCTC), Cobalt-Chrome/Zirconium/Titanium coating (CCZTC), Pure Titanium Standard (PTST), Steel, TAN Standard (TANST) and TAN new finish (TANNEW). Surgery was performed on 7 sheep, with 18 implants per sheep, for a total of 63 implants. After 8 weeks, the specimens were harvested and evaluated macroscopically, radiologically, biomechanically (removal torque), histomorphometrically and histologically. Results Cobalt-Chrome screws showed significantly (p = 0.031) lower removal torque values than pure titanium screws and also a tendency towards lower values compared to the other materials, except for steel. Steel screws showed no significant differences, in comparison to cobalt-chrome and TANST, however also a trend towards lower torque values than the remaining materials. The results of the fluorescence sections agreed with those of the biomechanical test. Histomorphometrically, there were no significant differences of bone area between the groups. The BIC (bone-to-implant-contact), used for the assessment of the osseointegration, was significantly lower for cobalt-chrome, compared to steel (p = 0.001). Steel again showed a lower ratio (p = 0.0001) compared to the other materials. Conclusion This study demonstrated that cobalt-chrome and steel show less osseointegration than the other metals and metal-alloys. However, osseointegration of cobalt-chrome was improved by zirconium and/or titanium based coatings (CCTC, TANST, TAN, TANNEW) being similar as pure titanium in their osseointegrative behavior. PMID:22400715

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

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum...

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

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum...

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

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum...

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

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum...

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

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section 73.3110a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum...

Catalyzed sodium chlorate candles

NASA Technical Reports Server (NTRS)

Malich, C. W.; Wydeven, T.

1972-01-01

The catalytic effect of cobalt powder on chlorate decomposition has been confirmed. Catalysis is enhanced by oxidation of the metal during burning. Catalysts other than cobalt compounds should also be effective; the complete elimination of fuel has shown that the oxidation of cobalt during decomposition is not a vital factor in the improved performance of catalyzed candles.

21 CFR 189.120 - Cobaltous salts and its derivatives.

Code of Federal Regulations, 2010 CFR

2010-04-01

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

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-08

... 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Significant New Use Rule AGENCY: Environmental... lithium manganese nickel oxide (CAS No. 182442-95-1), which was the subject of premanufacture notice (PMN... 5(a)(2) (15 U.S.C. 2604(a)(2)) for the chemical substance identified as cobalt lithium manganese...

21 CFR 189.120 - Cobaltous salts and its derivatives.

Code of Federal Regulations, 2011 CFR

2011-04-01

... malt beverages as a foam stabilizer and to prevent “gushing.” (b) Food containing any added cobaltous... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Cobaltous salts and its derivatives. 189.120 Section 189.120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

Recovery of Cobalt from leach solution of spent oil Hydrodesulphurization catalyst using a synergistic system consisting of VersaticTM10 and Cyanex®272

NASA Astrophysics Data System (ADS)

Yuliusman; Ramadhan, I. T.; Huda, M.

2018-03-01

Catalyst are often used in the petroleum refinery industry, especially cobalt-based catalyst such as CoMoX. Every year, Indonesia’s oil industry produces around 1350 tons of spent hydrodesulphurization catalyst in which cobalt makes up for 7%wt. of them. Cobalt is a non-renewable and highly valuable resource. Taking into account the aforementioned reasons, this research was made to recover cobalt from spent hydrodesulphurization catalyst so that it can be reused by industries needing them. The methods used in the recovery of cobalt from the waste catalyst leach solution are liquid-liquid extraction using a synergistic system of VersaticTM 10 and Cyanex®272. Based on the experiments done using the aforementioned methods and materials, the optimum condition for the extraction process: concentration of VersaticTM 10 of 0.35 M, Cyanex®272 of 0.25 M, temperature of 23-25°C (room temperature), and pH of 6 with an extraction percentage of 98.80% and co-extraction of Ni at 93.51%.

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

NASA Astrophysics Data System (ADS)

Raekelboom, E.; Cuevas, F.; Knosp, B.; Percheron-Guégan, A.

The effect of cobalt and manganese content on the dehydrogenation properties of air-exposed MmB 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 5+ x alloys is found to be beneficial for the hydrogen desorption kinetics in both processes.

Fischer-Tropsch Cobalt Catalyst Activation and Handling Through Wax Enclosure Methods

NASA Technical Reports Server (NTRS)

Klettlinger, Jennifer L. S.; Yen, Chia H.; Nakley, Leah M.; Surgenor, Angela D.

2016-01-01

Fischer-Tropsch (F-T) synthesis is considered a gas to liquid process which converts syn-gas, a gaseous mixture of hydrogen and carbon monoxide, into liquids of various hydrocarbon chain length and product distributions. Cobalt based catalysts are used in F-T synthesis and are the focus of this paper. One key concern with handling cobalt based catalysts is that the active form of catalyst is in a reduced state, metallic cobalt, which oxidizes readily in air. In laboratory experiments, the precursor cobalt oxide catalyst is activated in a fixed bed at 350 ?C then transferred into a continuous stirred tank reactor (CSTR) with inert gas. NASA has developed a process which involves the enclosure of active cobalt catalyst in a wax mold to prevent oxidation during storage and handling. This improved method allows for precise catalyst loading and delivery into a CSTR. Preliminary results indicate similar activity levels in the F-T reaction in comparison to the direct injection method. The work in this paper was supported by the NASA Fundamental Aeronautics Subsonics Fixed Wing Project.

Synthesis and application of a new thiazolylazo reagent for cloud point extraction and determination of cobalt in pharmaceutical preparations.

PubMed

Yamaki, Regina Terumi; Nunes, Luana Sena; de Oliveira, Hygor Rodrigues; Araújo, André S; Bezerra, Marcos Almeida; Lemos, Valfredo Azevedo

2011-01-01

The synthesis and characterization of the reagent 2-(5-bromothiazolylazo)-4-chlorophenol and its application in the development of a preconcentration procedure for cobalt determination using flame atomic absorption spectrometry after cloud point extraction is presented. This procedure is based on cobalt complexing and entrapment of the metal chelates into micelles of a surfactant-rich phase of Triton X-114. The preconcentration procedure was optimized by using a response surface methodology through the application of the Box-Behnken matrix. Under optimum conditions, the procedure determined the presence of cobalt with an LOD of 2.8 microg/L and LOQ of 9.3 microg/L. The enrichment factor obtained was 25. The precision was evaluated as the RSD, which was 5.5% for 10 microg/L cobalt and 6.9% for 30 microg/L. The accuracy of the procedure was assessed by comparing the results with those found using inductively coupled plasma-optical emission spectrometry. After validation, the procedure was applied to the determination of cobalt in pharmaceutical preparation samples containing cobalamin (vitamin B12).

New perspectives of cobalt tris(bipyridine) system: anti-cancer effect and its collateral sensitivity towards multidrug-resistant (MDR) cancers

PubMed Central

Mok, Simon Wing Fai; Liu, Hauwei; Zeng, Wu; Han, Yu; Gordillo-Martinez, Flora; Chan, Wai-Kit; Wong, Keith Man-Chung; Wong, Vincent Kam Wai

2017-01-01

Platinating compounds including cisplatin, carboplatin, and oxaliplatin are common chemotherapeutic agents, however, patients developed resistance to these clinical agents after initial therapeutic treatments. Therefore, different approaches have been applied to identify novel therapeutic agents, molecular mechanisms, and targets for overcoming drug resistance. In this study, we have identified a panel of cobalt complexes that were able to specifically induce collateral sensitivity in taxol-resistant and p53-deficient cancer cells. Consistently, our reported anti-cancer functions of cobalt complexes 1–6 towards multidrug-resistant cancers have suggested the protective and non-toxic properties of cobalt metal-ions based compounds in anti-cancer therapies. As demonstrated in xenograft mouse model, our results also confirmed the identified cobalt complex 2 was able to suppress tumor growth in vivo. The anti-cancer effect of the cobalt complex 2 was further demonstrated to be exerted via the induction of autophagy, cell cycle arrest, and inhibition of cell invasion and P-glycoprotein (P-gp) activity. These data have provided alternative metal ion compounds for targeting drug resistance cancers in chemotherapies. PMID:28903398

Physiological Remediation of Cobalt Ferrite Nanoparticles by Ferritin

NASA Astrophysics Data System (ADS)

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.

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

PubMed

Venkatesan, Kaliyamoorthy; Rajan Babu, Dhanakotti; Kavya Bai, Mane Prabhu; Supriya, Ravi; Vidya, Radhakrishnan; Madeswaran, Saminathan; Anandan, Pandurangan; Arivanandhan, Mukannan; Hayakawa, Yasuhiro

2015-01-01

Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4) magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311) of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed.

Experimental identification of the active sites in pyrolyzed carbon-supported cobalt-polypyrrole-4-toluenesulfinic acid as electrocatalysts for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Sha, Hao-Dong; Yuan, Xianxia; Li, Lin; Ma, Zhong; Ma, Zi-Feng; Zhang, Lei; Zhang, Jiujun

2014-06-01

A series of carbon supported cobalt-polypyrrole-4-toluenesulfinic acid have been pyrolyzed in an argon atmosphere at 800 °C, then structurally characterized and electrochemically evaluated as oxygen reduction reaction (ORR) catalysts in aqueous 0.5 M sulfuric acid. The structures are cobalt bonded to nitrogen species (Co-Nx) along with metallic cobalt and cobalt oxide. When the cobalt loading in the compound is less than 1.0 wt%, the predominate form is Co-Nx, when the loading is higher than 1.0 wt%, metallic Co and Co oxide particles co-exist with the Co-Nx compound. At a Co loading of ∼1.0 wt%, the catalyst gives the best ORR activity. Both metallic Co and Co oxide are not active for catalyzing ORR, and block the catalytically active Co-Nx species from the surface and reduce the catalytic activity since the diffusion limiting current density on a rotating disk electrode (RDE) increases when the electrode blocking agents are washed away with acid.

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

PubMed Central

Venkatesan, Kaliyamoorthy; Rajan Babu, Dhanakotti; Kavya Bai, Mane Prabhu; Supriya, Ravi; Vidya, Radhakrishnan; Madeswaran, Saminathan; Anandan, Pandurangan; Arivanandhan, Mukannan; Hayakawa, Yasuhiro

2015-01-01

Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4) magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311) of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed. PMID:26491320

Structural and surface changes of cobalt modified manganese oxide during activation and ethanol steam reforming reaction

NASA Astrophysics Data System (ADS)

Gac, Wojciech; Greluk, Magdalena; Słowik, Grzegorz; Turczyniak-Surdacka, Sylwia

2018-05-01

Surface and structural changes of unmodified manganese and cobalt-manganese oxide during activation and ethanol steam reforming reaction conditions (ESR) were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction/oxidation (TPR/TPO) and transmission electron microscopy. It was shown that synthesis of cobalt manganese oxide by the redox precipitation method led to the formation of strongly dispersed cobalt ionic species within cryptomelane-based manganese oxide structure. Development of large cube-like MnO nanoparticles with spherical cobalt metallic crystallites decorated by manganese oxide on the high oxidation state and potassium species was observed during reduction. Cobalt manganese catalyst showed high initial activity and selectivity to H2 and CO2 in ethanol stem reforming reaction in the range of 390-480 °C. The drop of ethanol conversion and changes of selectivity with the time-on-stream were observed. An increase of reaction temperature led to intensification of deactivation phenomena. TEM studies evidenced coexistence of Co and CoOx nanoparticles formed under ethanol steam reforming conditions, partially covered by filamentous and encapsulating carbonaceous deposits.

Structural elucidation, EPR and magnetic property of a Co(III) complex salt incorporating 4,4‧-bipyridine and 5-sulfoisophthalate

NASA Astrophysics Data System (ADS)

Das, Kuheli; Datta, Amitabha; Pevec, Andrej; Mane, Sandeep B.; Rameez, Mohammad; Garribba, Eugenio; Akitsu, Takashiro; Tanka, Shinnosuke

2018-01-01

The cobalt(III) derivative [Co3(sip)4(bipy)2(H2O)10][Co(bipy)2(H2O)4]3(sip)2·20H2O (1) has been hydro(solvo) thermally synthesized by combining sodium 5-sulfoisophthalate (sipH2Na) as organic linker, divalent cobalt nitrate hexahydrate as metal salt and the flexible N-donor ancillary ligand bipy (4,4‧-bipyridine). Compound 1 is an ionic solid consisting of both cobalt containing cations and anions and also in addition 5-sulfoisophthalate anions. Cobalt containing cations in the crystal structure are mononuclear complex while cobalt containing anion is a discrete trinuclear species. The π-π interaction present in 1 results in chain supramolecular structure. The encapsulation of the cobalt compound displays a moderate luminescent property. On temperature dependent magnetic study, it is revealed that the corresponding effective magnetic moment is 5.27 B.M. at 300 K, which suggests isolated Co(III) species with S = 2 (theoretical value is 4.90 B M.) and thus 1 shows a rare paramagnetic behavior.

Coordination chemistry of 6-thioguanine derivatives with cobalt: toward formation of electrical conductive one-dimensional coordination polymers.

PubMed

Amo-Ochoa, Pilar; Alexandre, Simone S; Hribesh, Samira; Galindo, Miguel A; Castillo, Oscar; Gómez-García, Carlos J; Pike, Andrew R; Soler, José M; Houlton, Andrew; Zamora, Félix; Harrington, Ross W; Clegg, William

2013-05-06

In this work we have synthetized and characterized by X-ray diffraction five cobalt complexes with 6-thioguanine (6-ThioGH), 6-thioguanosine (6-ThioGuoH), or 2'-deoxy-6-thioguanosine (2'-d-6-ThioGuoH) ligands. In all cases, these ligands coordinate to cobalt via N7 and S6 forming a chelate ring. However, independently of reagents ratio, 6-ThioGH provided monodimensional cobalt(II) coordination polymers, in which the 6-ThioG(-) acts as bridging ligand. However, for 2'-d-6-ThioGuoH and 6-ThioGuoH, the structure directing effect of the sugar residue gives rise to mononuclear cobalt complexes which form extensive H-bond interactions to generate 3D supramolecular networks. Furthermore, with 2'-d-6-ThioGuoH the cobalt ion remains in the divalent state, whereas with 6-ThioGuoH oxidation occurs and Co(III) is found. The electrical and magnetic properties of the coordination polymers isolated have been studied and the results discussed with the aid of DFT calculations, in the context of molecular wires.

Subnanometer Cobalt-Hydroxide-Anchored N-Doped Carbon Nanotube Forest for Bifunctional Oxygen Catalyst.

PubMed

Kim, Ji Eun; Lim, Joonwon; Lee, Gil Yong; Choi, Sun Hee; Maiti, Uday Narayan; Lee, Won Jun; Lee, Ho Jin; Kim, Sang Ouk

2016-01-27

Electrochemical oxygen redox reactions are the crucial elements for energy conversion and storage including fuel cells and metal air batteries. Despite tremendous research efforts, developing high-efficient, low-cost, and durable bifunctional oxygen catalysts remains a major challenge. We report a new class of hybrid material consisting of subnanometer thick amorphous cobalt hydroxide anchored on NCNT as a durable ORR/OER bifunctional catalyst. Although amorphous cobalt species-based catalysts are known as good OER catalysts, hybridizing with NCNT successfully enhanced ORR activity by promoting a 4e reduction pathway. Abundant charge carriers in amorphous cobalt hydroxide are found to trigger the superior OER activity with high current density and low Tafel slope as low as 36 mV/decade. A remarkably high OER turnover frequency (TOF) of 2.3 s(-1) at an overpotential of 300 mV was obtained, one of the highest values reported so far. Moreover, the catalytic activity was maintained over 120 h of cycling. The unique subnanometer scale morphology of amorphous hydroxide cobalt species along with intimate cobalt species-NCNT interaction minimizes the deactivation of catalyst during prolonged repeated cycles.

Electroremovable Traceless Hydrazides for Cobalt-Catalyzed Electro-Oxidative C-H/N-H Activation with Internal Alkynes.

PubMed

Mei, Ruhuai; Sauermann, Nicolas; Oliveira, João C A; Ackermann, Lutz

2018-06-27

Electrochemical oxidative C-H/N-H activations have been accomplished with a versatile cobalt catalyst in terms of [4 + 2] annulations of internal alkynes. The electro-oxidative C-H activation manifold proved viable with an undivided cell setup under exceedingly mild reaction conditions at room temperature using earth-abundant cobalt catalysts. The electrochemical cobalt catalysis prevents the use of transition metal oxidants in C-H activation catalysis, generating H 2 as the sole byproduct. Detailed mechanistic studies provided strong support for a facile C-H cobaltation by an initially formed cobalt(III) catalyst. The subsequent alkyne migratory insertion was interrogated by mass spectrometry and DFT calculations, providing strong support for a facile C-H activation and the formation of a key seven-membered cobalta(III) cycle in a regioselective fashion. Key to success for the unprecedented use of internal alkynes in electrochemical C-H/N-H activations was represented by the use of N-2-pyridylhydrazides, for which we developed a traceless electrocleavage strategy by electroreductive samarium catalysis at room temperature.

Synthesis and properties of precipitated cobalt ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Ristic, Mira; Krehula, Stjepko; Reissner, Michael; Jean, Malick; Hannoyer, Beatrice; Musić, Svetozar

2017-07-01

The formation and properties of cobalt ferrite were investigated with XRD, FT-IR, FE-SEM, Mössbauer and magnetometry. Cobalt ferrite samples were prepared (a) by combining coprecipitation Co(OH)2/2Fe(OH)3, using NaOH between pH 5.2 and 11.4 and autoclaving, and (b) by autoclaving the Co(OH)2/2Fe(OH)3 coprecipitate in a very strong alkaline medium. XRD and FE SEM showed that both CoFe2O4 crystallites and particles were in the nanosize range. The FT-IR spectra were typical of spinel ferrites. Cobalt ferrite precipitated at pH 7.2 and at 11.4 contained a small fraction of α-Fe2O3, whereas in the sample precipitated at pH 11.4 a very small amount (traces) of α-FeOOH were detected by FT-IR, additionally. Parameters obtained by Mössbauer spectroscopy suggested a structural migration of cobalt and iron ions in prepared cobalt ferrite spinels with the prolonged time of autoclaving. Magnetic measurements showed the magnetic behaviour typical of spinel ferrite nanoparticles.

Physiological Remediation of Cobalt Ferrite Nanoparticles by Ferritin

PubMed Central

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. PMID:28067263

Influence of silicon on friction and wear of iron-cobalt alloys

NASA Technical Reports Server (NTRS)

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

1972-01-01

Sliding friction and wear experiments were conducted with ternary ordered alloys of iron and cobalt containing various amounts of silicon to 5 weight percent. The friction and wear of these alloys were compared to those for binary iron-cobalt alloys in the ordered and disordered states and to those for the conventionally used bearing material, 440-C. Environments in which experiments were conducted included air, argon, and 0.25percent stearic acid in hexadecane. Results indicate that a ternary iron - cobalt - 5-percent-silicon alloy exhibits lower friction and wear than the simple binary iron-cobalt alloy. It exhibits lower wear than 440-C in all three environments. Friction was lower for the alloy in argon than in air. Auger analysis of the surface of the ternary alloy indicated segregation of silicon at the surface as a result of sliding.

Cobalt sorption onto anaerobic granular sludge: isotherm and spatial localization analysis.

PubMed

van Hullebusch, Eric D; Gieteling, Jarno; Zhang, Min; Zandvoort, Marcel H; Daele, Wim Van; Defrancq, Jacques; Lens, Piet N L

2006-01-24

This study investigated the effect of different feeding regimes on the cobalt sorption capacity of anaerobic granular sludge from a full-scale bioreactor treating paper mill wastewater. Adsorption experiments were done with non-fed granules in monometal (only Co) and competitive conditions (Co and Ni in equimolar concentrations). In order to modify the extracellular polymeric substances and sulfides content of the granules, the sludge was fed for 30 days with glucose (pH 7, 30 degrees C, organic loading rate=1.2 g glucose l(-1) day-1) in the presence (COD/SO4(2-)=1) or absence of sulfate. The partitioning of the sorbed cobalt between the exchangeable, carbonates, organic matter/sulfides and residual fractions was determined using a sequential extraction procedure (modified Tessier). Experimental equilibrium sorption data for cobalt were analysed by the Langmuir, Freundlich and Redlich-Peterson isotherm equations. The total Langmuir maximal sorption capacity of the sludge fed with glucose and sulfate loaded with cobalt alone displayed a significantly higher maximal cobalt sorption (Qmax =18.76 mg g-1 TSS) than the sludge fed with glucose alone (Qmax =13.21 mg g-1 TSS), essentially due to an increased sorption capacity of the exchangeable (30-107%) and organic/sulfides fractions (70-30%). Environmental scanning electron microscopy coupled with an energy dispersive X-ray analysis of granular cross-sections showed that mainly iron minerals (i.e. iron sulfides) were involved in the cobalt accumulation. Moreover, the sorbed cobalt was mainly located at the edge of the granules. The sorption characteristics of the exchangeable and carbonates fractions fitted well to the Redlich-Peterson model (intermediate multi-layer sorption behaviour), whereas the sorption characteristics of the organic matter/sulfides and residual fractions fitted well to the Langmuir model (monolayer sorption behaviour). The organic matter/sulfides fraction displayed the highest affinity for cobalt for the three sludge types investigated.

Regulation of the Cobalt/Nickel Efflux Operon dmeRF in Agrobacterium tumefaciens and a Link between the Iron-Sensing Regulator RirA and Cobalt/Nickel Resistance

PubMed Central

Dokpikul, Thanittra; Chaoprasid, Paweena; Saninjuk, Kritsakorn; Sirirakphaisarn, Sirin; Johnrod, Jaruwan; Nookabkaew, Sumontha; Mongkolsuk, Skorn

2016-01-01

ABSTRACT The Agrobacterium tumefaciens C58 genome harbors an operon containing the dmeR (Atu0890) and dmeF (Atu0891) genes, which encode a transcriptional regulatory protein belonging to the RcnR/CsoR family and a metal efflux protein belonging to the cation diffusion facilitator (CDF) family, respectively. The dmeRF operon is specifically induced by cobalt and nickel, with cobalt being the more potent inducer. Promoter-lacZ transcriptional fusion, an electrophoretic mobility shift assay, and DNase I footprinting assays revealed that DmeR represses dmeRF transcription through direct binding to the promoter region upstream of dmeR. A strain lacking dmeF showed increased accumulation of intracellular cobalt and nickel and exhibited hypersensitivity to these metals; however, this strain displayed full virulence, comparable to that of the wild-type strain, when infecting a Nicotiana benthamiana plant model under the tested conditions. Cobalt, but not nickel, increased the expression of many iron-responsive genes and reduced the induction of the SoxR-regulated gene sodBII. Furthermore, control of iron homeostasis via RirA is important for the ability of A. tumefaciens to cope with cobalt and nickel toxicity. IMPORTANCE The molecular mechanism of the regulation of dmeRF transcription by DmeR was demonstrated. This work provides evidence of a direct interaction of apo-DmeR with the corresponding DNA operator site in vitro. The recognition site for apo-DmeR consists of 10-bp AT-rich inverted repeats separated by six C bases (5′-ATATAGTATACCCCCCTATAGTATAT-3′). Cobalt and nickel cause DmeR to dissociate from the dmeRF promoter, which leads to expression of the metal efflux gene dmeF. This work also revealed a connection between iron homeostasis and cobalt/nickel resistance in A. tumefaciens. PMID:27235438

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

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Cobalt chloride attenuates hypobaric hypoxia induced vascular leakage in rat brain: Molecular mechanisms of action of cobalt chloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalpana, S.; Dhananjay, S.; Anju, B.

2008-09-15

This study reports the efficacy of cobalt preconditioning in preventing hypobaric hypoxia induced vascular leakage (an indicator of cerebral edema) using male Sprague-Dawley rats as model system. Exposure of animals to hypobaric hypoxia led to a significant increase in vascular leakage, reactive oxygen species (ROS), nitric oxide (NO), and vascular endothelial growth factor (VEGF) levels. There was a marked increase in Nuclear Factor {kappa}B (NF{kappa}B) DNA binding activity and levels of pro-inflammatory cytokines such as Monocyte chemoattractant protein (MCP-1), Interferon-{gamma} (IFN-{gamma}), Interleukin-1 (IL-1), and Tumor Necrosis Factor-{alpha} (TNF-{alpha}) and cell adhesion molecules such as Vascular Cell Adhesion Molecule-1 (VCAM-1), andmore » P-selectin. Chemical preconditioning by cobalt for 7 days (12.5 mg Co/kg b.w., oral) significantly attenuated cerebral vascular leakage and the expression of inflammatory mediators induced by hypoxia. Administration of NF{kappa}B inhibitor, curcumin (50 mg/kg b.w.; i.p.) appreciably inhibited hypoxia induced vascular leakage indicating the involvement of NF{kappa}B in causing vascular leakage. Interestingly, cobalt when administered at 12.5 mg Co/kg b.w. (i.p.), 1 h before hypoxia could not prevent the vascular leakage indicating that cobalt per se did not have an effect on NF{kappa}B. The lower levels of NF{kappa}B observed in the brains of cobalt administered animals might be due to higher levels of antioxidant and anti-inflammatory proteins (hemeoxygenase-1 and metallothionein). To conclude cobalt preconditioning inhibited hypobaric hypoxia induced cerebral vascular leakage by lowering NF{kappa}B DNA binding activity and its regulated pro-inflammatory mediators. This is contemplated to be mediated by cobalt induced reduction in ROS/NO and increase in HO-1 and MT.« less

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

PubMed Central

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

2013-01-01

Study Objectives: Exposure to the variable oxygenation patterns in obstructive sleep apnea (OSA) causes oxidative stress within the brain. We hypothesized that this stress is associated with increased levels of redox-active metals and white matter injury. Design: Participants were randomly allocated to a control or experimental group (single independent variable). Setting: University animal house. Participants: Adult male C57BL/6J mice. Interventions: To model OSA, mice were exposed to long-term intermittent hypoxia (LTIH) for 10 hours/day for 8 weeks or sham intermittent hypoxia (SIH). Measurements and Results: Laser ablation-inductively coupled plasma-mass spectrometry was used to quantitatively map the distribution of the trace elements cobalt, copper, iron, and zinc in forebrain sections. Control mice contained 62 ± 7 ng cobalt/g wet weight, whereas LTIH mice contained 5600 ± 600 ng cobalt/g wet weight (P < 0.0001). Other elements were unchanged between conditions. Cobalt was concentrated within white matter regions of the brain, including the corpus callosum. Compared to that of control mice, the corpus callosum of LTIH mice had significantly more endoplasmic reticulum stress, fewer myelin-associated proteins, disorganized myelin sheaths, and more degenerated axon profiles. Because cobalt is an essential component of vitamin B12, serum methylmalonic acid (MMA) levels were measured. LTIH mice had low MMA levels (P < 0.0001), indicative of increased B12 activity. Conclusions: Long-term intermittent hypoxia increases brain cobalt, predominantly in the white matter. The increased cobalt is associated with endoplasmic reticulum stress, myelin loss, and axonal injury. Low plasma methylmalonic acid levels are associated with white matter injury in long-term intermittent hypoxia and possibly in obstructive sleep apnea. Citation: Veasey SC; Lear J; Zhu Y; Grinspan JB; Hare DJ; Wang S; Bunch D; Doble PA; Robinson SR. Long-term intermittent hypoxia elevates cobalt levels in the brain and injures white matter in adult mice. SLEEP 2013;36(10):1471-1481. PMID:24082306

ALHAT COBALT: CoOperative Blending of Autonomous Landing Technology

NASA Technical Reports Server (NTRS)

Carson, John M.

2015-01-01

The COBALT project is a flight demonstration of two NASA ALHAT (Autonomous precision Landing and Hazard Avoidance Technology) capabilities that are key for future robotic or human landing GN&C (Guidance, Navigation and Control) systems. The COBALT payload integrates the Navigation Doppler Lidar (NDL) for ultraprecise velocity and range measurements with the Lander Vision System (LVS) for Terrain Relative Navigation (TRN) position estimates. Terrestrial flight tests of the COBALT payload in an open-loop and closed-loop GN&C configuration will be conducted onboard a commercial, rocket-propulsive Vertical Test Bed (VTB) at a test range in Mojave, CA.

Photocatalytic CO 2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO 2, CO, or Proton

DOE PAGES

Shimoda, Tomoe; Morishima, Takeshi; Kodama, Koichi; ...

2018-04-26

Trigonal-bipyramidal Co(II) complexes are used for photochemical carbon dioxide (CO 2) reduction with Ru(bpy) 3 2+ as a photosensitizer, tri-p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor to produce carbon monoxide and dihydrogen. Here, the CO 2 reduction is slow because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for reduction to catalytically active Co(0) by the photoproduced [Ru(bpy) 3] +.

Photocatalytic CO 2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO 2, CO, or Proton

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shimoda, Tomoe; Morishima, Takeshi; Kodama, Koichi

Trigonal-bipyramidal Co(II) complexes are used for photochemical carbon dioxide (CO 2) reduction with Ru(bpy) 3 2+ as a photosensitizer, tri-p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor to produce carbon monoxide and dihydrogen. Here, the CO 2 reduction is slow because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for reduction to catalytically active Co(0) by the photoproduced [Ru(bpy) 3] +.

Porous Cobalt Phosphide Polyhedrons with Iron Doping as an Efficient Bifunctional Electrocatalyst.

PubMed

Li, Feng; Bu, Yunfei; Lv, Zijian; Mahmood, Javeed; Han, Gao-Feng; Ahmad, Ishfaq; Kim, Guntae; Zhong, Qin; Baek, Jong-Beom

2017-10-01

Iron (Fe)-doped porous cobalt phosphide polyhedrons are designed and synthesized as an efficient bifunctional electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The synthesis strategy involves one-step route for doping foreign metallic element and forming porous cobalt phosphide polyhedrons. With varying doping levels of Fe, the optimized Fe-doped porous cobalt phosphide polyhedron exhibits significantly enhanced HER and OER performances, including low onset overpotentials, large current densities, as well as small Tafel slopes and good electrochemical stability during HER and OER. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effects of Pulse Current Plating on the Mechanical Properties of Cobalt and Cobalt-Al2O3

DTIC Science & Technology

1977-04-01

258. Branson cobalt deposits as a function ol cu rrent pulses superImposed on Ultrasonic Corp.) was used tominimi,eAl ..0 agglomeration in a back...intens ify nucleation and growth processes leading to a Iheauthors wishtot hank Mr. Richard Carte rforprepar ingthe re finement in grain structure...i N BOX CM , I)UKE STATION ATTN : A~.1\\5T..SD ATTN : RI)Rl)- IP L 220 “III SIR E !~T N .E . Du RHAM , NC 27706 C1LARI U l’Tl Sv ILI.I. , VA 22901 Cl)R

Relating FTS Catalyst Properties to Performance

NASA Technical Reports Server (NTRS)

Ma, Wenping; Ramana Rao Pendyala, Venkat; Gao, Pei; Jermwongratanachai, Thani; Jacobs, Gary; Davis, Burton H.

2016-01-01

During the reporting period June 23, 2011 to August 31, 2013, CAER researchers carried out research in two areas of fundamental importance to the topic of cobalt-based Fischer-Tropsch Synthesis (FTS): promoters and stability. The first area was research into possible substitute promoters that might be used to replace the expensive promoters (e.g., Pt, Re, and Ru) that are commonly used. To that end, three separate investigations were carried out. Due to the strong support interaction of ?-Al2O3 with cobalt, metal promoters are commonly added to commercial FTS catalysts to facilitate the reduction of cobalt oxides and thereby boost active surface cobalt metal sites. To date, the metal promoters examined have been those up to and including Group 11. Because two Group 11 promoters (i.e., Ag and Au) were identified to exhibit positive impacts on conversion, selectivity, or both, research was undertaken to explore metals in Groups 12 - 14. The three metals selected for this purpose were Cd, In, and Sn. At a higher loading of 25%Co on alumina, 1% addition of Cd, In, or Sn was found to-on average-facilitate reduction by promoting a heterogeneous distribution of cobalt consisting of larger lesser interacting cobalt clusters and smaller strongly interacting cobalt species. The lesser interacting species were identified in TPR profiles, where a sharp low temperature peak occurred for the reduction of larger, weakly interacting, CoO species. In XANES, the Cd, In, and Sn promoters were found to exist as oxides, whereas typical promoters (e.g., Re, Ru, Pt) were previously determined to exist in an metallic state in atomic coordination with cobalt. The larger cobalt clusters significantly decreased the active site density relative to the unpromoted 25%Co/Al2O3 catalyst. Decreasing the cobalt loading to 15%Co eliminated the large non-interacting species. The TPR peak for reduction of strongly interacting CoO in the Cd promoted catalyst occurred at a measurably lower temperature than in the unpromoted catalyst. Nevertheless, the Co clusters remained slightly larger, on average, in comparison with the unpromoted 15%Co/Al2O3 reference catalyst. None of the promoted catalysts (i.e., with Cd, In, or Sn) exhibited surface Co0 site densities higher than that of the unpromoted catalyst. In activity testing, the activities were even much lower than what was expected from the H2-TPD results. Two possible explanations were proposed: (1) the promoters may be located on the surfaces of cobalt particles, blocking surface Co0 but being able to desorb hydrogen or (2) the promoters may facilitate Co oxidation during FTS, as previously observed by Huffman and coworkers when K was added to cobalt catalysts.

Synthesis of cobalt alloy through smelting method and its characterization as prosthesis bone implant

NASA Astrophysics Data System (ADS)

Aminatun, Putri, N. S. Efinda; Indriani, Arista; Himawati, Umi; Hikmawati, Dyah; Suhariningsih

2014-09-01

Cobalt-based alloys are widely used as total hip and knee replacements because of their excellent properties, such as corrosion resistance, fatigue strength and biocompatibility. In this work, cobalt alloys with variation of Cr (28.5; 30; 31.5; 33, and 34.5% wt) have been synthesized by smelting method began with the process of compaction, followed by smelting process using Tri Arc Melting Furnace at 200A. Continued by homogenization process at recrystallization temperature (1250° C) for 3 hours to allow the atoms diffuses and transform into γ phase. The next process is rolling process which is accompanied by heating at 1200° C for ± 15 minutes and followed by quenching. This process is repeated until the obtained thickness of ± 1 mm. The evaluated material properties included microstructure, surface morphology, and hardness value. It was shown that microstructure of cobalt alloys with variation of Cr is dominant by γ phase, thus making the entire cobalt alloys have high hardness. It was also shown from the surface morphology of entire cobalt alloys sample indicated the whole process of synthesis that had good solubility were at flat surface area. Hardness value test showed all of cobalt alloys sample had high hardness, just variation of 33% Cr be in the range of ASTMF75, it were 345,24 VHN which is potential to be applied as an implant prosthesis.

Effect of electrical spot welding on load deflection rate of orthodontic wires.

PubMed

Alavi, Shiva; Abrishami, Arezoo

2015-01-01

One of the methods used for joining metals together is welding, which can be carried out using different techniques such as electric spot welding. This study evaluated the effect of electric spot welding on the load deflection rate of stainless steel and chromium-cobalt orthodontic wires. In this experimental-laboratory study, load deflection rate of 0.016 × 0.022 inch stainless steel and chromium cobalt wires were evaluated in five groups (n =18): group one: Stainless steel wires, group two: chromium-cobalt wires, group three: stainless steel wires welded to stainless steel wires, group four: Stainless steel wires welded to chromium-cobalt wires, group five: chromium-cobalt wire welded to chromium-cobalt wires. Afterward, the forces induced by the samples in 0.5 mm, 1 mm, 1.5 mm deflection were measured using a universal testing machine. Then mean force measured for each group was compared with other groups. The data were analyzed using repeated measure analysis of variance (ANOVA), one-way ANOVA, and paired t-test by the SPSS software. The significance level was set as 0.05. The Tukey test showed that there were significant differences between the load deflection rates of welded groups compared to control ones (P < 0.001). Considering the limitation of this study, the electric spot welding process performed on stainless steel and chromium-cobalt wires increased their load deflection rates.

Cobalt compounds as antidotes for hydrocyanic acid

PubMed Central

Evans, C. Lovatt

1964-01-01

The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5×LD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5×LD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3×LD50) than for mice (2×LD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered. PMID:14256807

[Determination of tungsten and cobalt in the air of workplace by ICP-OES].

PubMed

Zhang, J; Ding, C G; Li, H B; Song, S; Yan, H F

2017-08-20

Objective: To establish the inductively coupled plasma optical emission spectrometry (ICP-OES) method for determination of cobalt and tungsten in the air of workplace. Methods: The cobalt and tungsten were collected by filter membrane and then digested by nitric acid, inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the detection of cobalt and tungsten. Results: The linearity of tungsten was good at the range of 0.01-1 000 μg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.006 7 μg/ml and 0.022 μg/ml, respectively. The recovery was ranged from 98%-101%, the RSD of intra-and inter-batch precision were 1.1%-3.0% and 2.1%-3.8%, respectively. The linearity of cobalt was good at the range of 0.01-100 μg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.001 2 μg/ml and 0.044 μg/ml, respectively. The recovery was ranged from 95%-97%, the RSD of intra-and inter-batch precision were 1.1%-2.4% and 1.1%-2.9%, respectively. The sampling efficiency of tungsten and cobalt were higher than 94%. Conclusion: The linear range, sensitivity and precision of the method was suitable for the detection of tungsten and cobalt in the air of workplace.

A comparison between cobalt and linear accelerator-based treatment plans for conformal and intensity-modulated radiotherapy.

PubMed

Adams, E J; Warrington, A P

2008-04-01

The simplicity of cobalt units gives them the advantage of reduced maintenance, running costs and downtime when compared with linear accelerators. However, treatments carried out on such units are typically limited to simple techniques. This study has explored the use of cobalt beams for conformal and intensity-modulated radiotherapy (IMRT). Six patients, covering a range of treatment sites, were planned using both X-ray photons (6/10 MV) and cobalt-60 gamma rays (1.17 and 1.33 MeV). A range of conformal and IMRT techniques were considered, as appropriate. Conformal plans created using cobalt beams for small breast, meningioma and parotid cases were found to compare well with those created using X-ray photons. By using additional fields, acceptable conformal plans were also created for oesophagus and prostate cases. IMRT plans were found to be of comparable quality for meningioma, parotid and thyroid cases on the basis of dose-volume histogram analysis. We conclude that it is possible to plan high-quality radical radiotherapy treatments for cobalt units. A well-designed beam blocking/compensation system would be required to enable a practical and efficient alternative to multileaf collimator (MLC)-based linac treatments to be offered. If cobalt units were to have such features incorporated into them, they could offer considerable benefits to the radiotherapy community.

Plasma boriding of a cobalt-chromium alloy as an interlayer for nanostructured diamond growth

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.; Jubinsky, Matthew; Catledge, Shane A.

2015-02-01

Chemical vapor deposited (CVD) diamond coatings can potentially improve the wear resistance of cobalt-chromium medical implant surfaces, but the high cobalt content in these alloys acts as a catalyst to form graphitic carbon. Boriding by high temperature liquid baths and powder packing has been shown to improve CVD diamond compatibility with cobalt alloys. We use the microwave plasma-enhanced (PE) CVD process to deposit interlayers composed primarily of the borides of cobalt and chromium. The use of diborane (B2H6) in the plasma feedgas allows for the formation of a robust boride interlayer for suppressing graphitic carbon during subsequent CVD of nano-structured diamond (NSD). This metal-boride interlayer is shown to be an effective diffusion barrier against elemental cobalt for improving nucleation and adhesion of NSD coatings on a CoCrMo alloy. Migration of elemental cobalt to the surface of the interlayer is significantly reduced and undetectable on the surface of the subsequently-grown NSD coating. The effects of PECVD boriding are compared for a range of substrate temperatures and deposition times and are evaluated using glancing-angle X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Raman spectroscopy. Boriding of CoCrMo results in adhered nanostructured diamond coatings with low surface roughness.

Understanding the roles of the strategic element cobalt in nickel base superalloys

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Dreshfield, R. L.

1983-01-01

The United States imports over 90% of its cobalt, chromium, columbium, and tantalum, all key elements in high temperature nickel base superalloys for aircraft gas turbine disks and airfoils. Research progress in understanding the roles of cobalt and some possible substitutes effects on microstructure, mechanical properties, and environmental resistance of turbine alloys is discussed.

Microwave Mapping Demonstration Using the Thermochromic Cobalt Chloride Equilibrium

ERIC Educational Resources Information Center

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…

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

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-18

... 2070-AB27 Cobalt Lithium Manganese Nickel Oxide; Withdrawal of Significant New Use Rule AGENCY... chemical substance identified as cobalt lithium manganese nickel oxide (CAS No. 182442-95-1), which was the... lithium manganese nickel oxide (PMN P-04-269; CAS No. 182442-95-1) at 40 CFR 721.10201 because the Agency...

Cobalt, manganese, and iron near the Hawaiian Islands: A potential concentrating mechanism for cobalt within a cyclonic eddy and implications for the hybrid-type trace metals

NASA Astrophysics Data System (ADS)

Noble, Abigail E.; Saito, Mak A.; Maiti, Kanchan; Benitez-Nelson, Claudia R.

2008-05-01

The vertical distributions of cobalt, iron, and manganese in the water column were studied during the E-Flux Program (E-Flux II and III), which focused on the biogeochemistry of cold-core cyclonic eddies that form in the lee of the Hawaiian Islands. During E-Flux II (January 2005) and E-Flux III (March 2005), 17 stations were sampled for cobalt ( n=147), all of which demonstrated nutrient-like depletion in surface waters. During E-Flux III, two depth profiles collected from within a mesoscale cold-core eddy, Cyclone Opal, revealed small distinct maxima in cobalt at ˜100 m depth and a larger inventory of cobalt within the eddy. We hypothesize that this was due to a cobalt concentrating effect within the eddy, where upwelled cobalt was subsequently associated with sinking particulate organic carbon (POC) via biological activity and was released at a depth coincident with nearly complete POC remineralization [Benitez-Nelson, C., Bidigare, R.R., Dickey, T.D., Landry, M.R., Leonard, C.L., Brown, S.L., Nencioli, F., Rii, Y.M., Maiti, K., Becker, J.W., Bibby, T.S., Black, W., Cai, W.J., Carlson, C.A., Chen, F., Kuwahara, V.S., Mahaffey, C., McAndrew, P.M., Quay, P.D., Rappe, M.S., Selph, K.E., Simmons, M.P., Yang, E.J., 2007. Mesoscale eddies drive increased silica export in the subtropical Pacific Ocean. Science 316, 1017-1020]. There is also evidence for the formation of a correlation between cobalt and soluble reactive phosphorus during E-Flux III relative to the E-Flux II cruise that we suggest is due to increased productivity, implying a minimum threshold of primary production below which cobalt-phosphate coupling does not occur. Dissolved iron was measured in E-Flux II and found in somewhat elevated concentrations (˜0.5 nM) in surface waters relative to the iron depleted waters of the surrounding Pacific [Fitzwater, S.E., Coale, K.H., Gordon, M.R., Johnson, K.S., Ondrusek, M.E., 1996. Iron deficiency and phytoplankton growth in the equatorial Pacific. Deep-Sea Research II 43 (4-6), 995-1015], possibly due to island effects associated with the iron-rich volcanic soil from the Hawaiian Islands and/or anthropogenic inputs. Distinct depth maxima in total dissolved cobalt were observed at 400-600 m depth, suggestive of the release of metals from the shelf area of comparable depth that surrounds these islands.

A Comparison of Blood Metal Ions in Total Hip Arthroplasty Using Metal and Ceramic Heads.

PubMed

White, Peter B; Meftah, Morteza; Ranawat, Amar S; Ranawat, Chitranjan S

2016-10-01

In recent time, metal ion debris and adverse local tissue reaction have reemerged as an area of clinical concern with the use of large femoral heads after total hip arthroplasty (THA). Between June 2014 and January 2015, 60 patients with a noncemented THA using a titanium (titanium, molybdenum, zirconium, and iron alloy) femoral stem and a V40 trunnion were identified with a minimum 5-year follow-up. All THAs had a 32- or 36-mm metal (n = 30) or ceramic (n = 30) femoral head coupled with highly cross-linked polyethylene. Cobalt, chromium, and nickel ions were measured. Patients with metal heads had detectable cobalt and chromium levels. Cobalt levels were detectable in 17 (56.7%) patients with a mean of 2.0 μg/L (range: <1.0-10.8 μg/L). Chromium levels were detectable in 5 (16.7%) patients with a mean of 0.3 μg/L (range: <1.0-2.2 μg/L). All patients with a ceramic head had nondetectable cobalt and chromium levels. Cobalt and chromium levels were significantly higher with metal heads compared to ceramic heads (P < .01). Cobalt levels were significantly higher with 36-mm metal heads compared with 32-mm heads (P < .01). Seven patients with metal femoral heads had mild hip symptoms, 4 of whom had positive findings of early adverse local tissue reaction on magnetic resonance imaging. All ceramic THA was asymptomatic. The incidence and magnitude of cobalt and chromium levels is higher in metal heads compared to ceramic heads with this implant system (P < .01). Thirty-six millimeter metal femoral heads result in larger levels of cobalt compared with 32-mm metal heads. Copyright © 2016 Elsevier Inc. All rights reserved.

[Metallurgical differentiation of cobalt-chromium alloys for implants].

PubMed

Holzwarth, U; Thomas, P; Kachler, W; Göske, J; Schuh, A

2005-10-01

Cobalt Chromium alloys are used in cemented total hip or knee arthroplasty as well as in metal-on-metal bearings in total hip arthroplasty. An increasing number of publications report about (allergic) reactions to wear particles of Cobalt Chromium alloys. Reactions to nickel are more frequent in comparison to Cobalt or Chromium particles. It is well known that different kinds of Cobalt Chromium alloys contain different amounts of alloying elements; nevertheless. The aim of the current work was to compare the different Cobalt Chromium alloys according to ASTM F or ISO standards in respect to the different alloying elements. Co28Cr6Mo casting alloys according to ASTM F 75 or ISO 5832-4 as well as forging alloy types according to ASTM F 799 and ISO 5832 such as Co20Cr15W10Ni, Co35Ni20Cr, Fe40Co20Cr10Ni, Co20Cr20Ni, and Co28Cr6Mo were analyzed in respect to their element content of Co, Cr, Ni, Mo, Fe, W, and Mn. In 1935 the Cobalt based alloy "Vitallium" Co30Cr5Mo basically used in the aircraft industry was introduced into medicine. The chemical composition of this alloy based on Cobalt showed 30 wt.% Chromium and 5 wt.% Molybdenum. The differentiation using alloy names showed no Nickel information in single alloy names. The information given about different alloys can lead to an unprecise evaluation of histopathological findings in respect to alloys or alloying constituents. Therefore, implant manufacturers should give the exact information about the alloys used and adhere to European law, Euronorm 93/42/EWG.

Selected aspects of the action of cobalt ions in the human body.

PubMed

Czarnek, Katarzyna; Terpiłowska, Sylwia; Siwicki, Andrzej K

2015-01-01

Cobalt is widespread in the natural environment and can be formed as an effect of anthropogenic activity. This element is used in numerous industrial applications and nuclear power plants. Cobalt is an essential trace element for the human body and can occur in organic and inorganic forms. The organic form is a necessary component of vitamin B12 and plays a very important role in forming amino acids and some proteins in nerve cells, and in creating neurotransmitters that are indispensable for correct functioning of the organism. Its excess or deficiency will influence it unfavourably. Salts of cobalt have been applied in medicine in the treatment of anaemia, as well as in sport as an attractive alternative to traditional blood doping. Inorganic forms of cobalt present in ion form, are toxic to the human body, and the longer they are stored in the body, the more changes they cause in cells. Cobalt gets into the body in several ways: firstly, with food; secondly by the respiratory system; thirdly, by the skin; and finally, as a component of biomaterials. Cobalt and its alloys are fundamental components in orthopaedic implants and have been used for about 40 years. The corrosion of metal is the main problem in the construction of implants. These released metal ions may cause type IV inflammatory and hypersensitivity reactions, and alternations in bone modelling that lead to aseptic loosening and implant failure. The ions of cobalt released from the surface of the implant are absorbed by present macrophages, which are involved in many of the processes associated with phagocytose orthopaedic biomaterials particles and release pro-inflammatory mediators such as interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor α (TNF-α), and prostaglandin.

Selected aspects of the action of cobalt ions in the human body

PubMed Central

Terpiłowska, Sylwia; Siwicki, Andrzej K.

2015-01-01

Cobalt is widespread in the natural environment and can be formed as an effect of anthropogenic activity. This element is used in numerous industrial applications and nuclear power plants. Cobalt is an essential trace element for the human body and can occur in organic and inorganic forms. The organic form is a necessary component of vitamin B12 and plays a very important role in forming amino acids and some proteins in nerve cells, and in creating neurotransmitters that are indispensable for correct functioning of the organism. Its excess or deficiency will influence it unfavourably. Salts of cobalt have been applied in medicine in the treatment of anaemia, as well as in sport as an attractive alternative to traditional blood doping. Inorganic forms of cobalt present in ion form, are toxic to the human body, and the longer they are stored in the body, the more changes they cause in cells. Cobalt gets into the body in several ways: firstly, with food; secondly by the respiratory system; thirdly, by the skin; and finally, as a component of biomaterials. Cobalt and its alloys are fundamental components in orthopaedic implants and have been used for about 40 years. The corrosion of metal is the main problem in the construction of implants. These released metal ions may cause type IV inflammatory and hypersensitivity reactions, and alternations in bone modelling that lead to aseptic loosening and implant failure. The ions of cobalt released from the surface of the implant are absorbed by present macrophages, which are involved in many of the processes associated with phagocytose orthopaedic biomaterials particles and release pro-inflammatory mediators such as interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor α (TNF-α), and prostaglandin. PMID:26557039

Mechanistic Studies of Cobalt-Catalyzed C(sp2)-H Borylation of Five-Membered Heteroarenes with Pinacolborane.

PubMed

Obligacion, Jennifer V; Chirik, Paul J

2017-07-07

Studies into the mechanism of cobalt-catalyzed C(sp 2 )-H borylation of five-membered heteroarenes with pinacolborane (HBPin) as the boron source established the catalyst resting state as the trans -cobalt(III) dihydride boryl, ( iPr PNP)Co(H) 2 (BPin) ( iPr PNP = 2,6-( i Pr 2 PCH 2 ) 2 (C 5 H 3 N)), at both low and high substrate conversions. The overall first-order rate law and observation of a normal deuterium kinetic isotope effect on the borylation of benzofuran versus benzofuran-2- d 1 support H 2 reductive elimination from the cobalt(III) dihydride boryl as the turnover-limiting step. These findings stand in contrast to that established previously for the borylation of 2,6-lutidine with the same cobalt precatalyst, where borylation of the 4-position of the pincer occurred faster than the substrate turnover and arene C-H activation by a cobalt(I) boryl is turnover-limiting. Evaluation of the catalytic activity of different cobalt precursors in the C-H borylation of benzofuran with HBPin established that the ligand design principles for C- H borylation depend on the identities of both the arene and the boron reagent used: electron-donating groups improve catalytic activity of the borylation of pyridines and arenes with B 2 Pin 2 , whereas electron-withdrawing groups improve catalytic activity of the borylation of five-membered heteroarenes with HBPin. Catalyst deactivation by P-C bond cleavage from a cobalt(I) hydride was observed in the C-H borylation of arene substrates with C-H bonds that are less acidic than those of five-membered heteroarenes using HBPin and explains the requirement of B 2 Pin 2 to achieve synthetically useful yields with these arene substrates.

Biological and protein-binding studies of newly synthesized polymer-cobalt(III) complexes.

PubMed

Vignesh, G; Pradeep, I; Arunachalam, S; Vignesh, S; Arthur James, R; Arun, R; Premkumar, K

2016-03-01

The polymer-cobalt(III) complexes, [Co(bpy)(dien)BPEI]Cl3 · 4H2O (bpy = 2,2'-bipyridine, dien = diethylentriamine, BPEI = branched polyethyleneimine) were synthesized and characterized. The interaction of these complexes with human serum albumin (HSA) and bovine serum albumin (BSA) was investigated under physiological conditions using various physico-chemical techniques. The results reveal that the fluorescence quenching of serum albumins by polymer-cobalt(III) complexes took place through static quenching. The binding of these complexes changed the molecular conformation of the protein considerably. The polymer-cobalt(III) complex with x = 0.365 shows antimicrobial activity against several human pathogens. This complex also induces cytotoxicity against MCF-7 through apoptotic induction. However, further studies are needed to decipher the molecular mode of action of polymer-cobalt(III) complex and for its possible utilization in anticancer therapy. Copyright © 2015 John Wiley & Sons, Ltd.

Hydrothermal synthesis of cobalt sulfide nanotubes: The size control and its application in supercapacitors

NASA Astrophysics Data System (ADS)

Wan, Houzhao; Ji, Xiao; Jiang, Jianjun; Yu, Jingwen; Miao, Ling; Zhang, Li; Bie, Shaowei; Chen, Haichao; Ruan, Yunjun

2013-12-01

Cobalt sulfide nanotubes are synthesized by hydrothermal method. The precursor is characterized by XRD, FTIR and SEM. We study the influence of temperature on the evolution of this special coarse shape nanostructure and analyze relationship between the sizes of cobalt sulfide nanotubes and the capacitive properties of active materials. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are used to study the effects of microstructure and morphology of the samples on their capacitance and conductivity. The specific capacitance of cobalt sulfide nanotubes (obtained in 80 °C) electrode exhibits a capacitance of 285 F g-1 at the current density of 0.5 A g-1 as well as rather good cycling stability. Moreover, during the cycling process, the coulombic efficiency remains 99%. The as-prepared cobalt sulfide nanotubes electrode exhibits excellent electrochemical performance as electrode materials for supercapacitors.

Low Temperature Synthesis of Cobalt-Chromium Carbide Nanoparticles-Doped Carbon Nanofibers.

PubMed

Yousef, Ayman; Brooks, Robert M; Abutaleb, Ahmed; Al-Deyab, Salem S; El-Newehy, Mohamed H

2018-04-01

Electrospinning has been used to synthesize cobalt-chromium carbide nanoparticles (NPs)-doped carbon nanofibers (CNFs) (Composite). Electrospun mat comprising of cobalt acetate, chromium acetate and poly(vinyl alcohol) (PVA) has been carbonized at low temperature (850 °C) for 3 h under argon atmosphere to produce the introduced composite. The process was achieved at low temperature due to the presence of cobalt as an activator. Field emission scanning electron microscope (FE-SEM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM) equipped with EDX techniques were used to determine the products characteristics. The results indicated the formation of pure cobalt (Co), Cr7C3 NPs and crystalline CNFs. The Co and Cr7C3 NPs were covered with CNFs. Overall, the proposed NFs open new avenue to prepare different metals-metal carbides-carbon NFs at low temperature and short reaction time.

Controllable synthesis of hierarchical nickel cobalt sulfide with enhanced electrochemical activity

NASA Astrophysics Data System (ADS)

Tie, Jinjin; Han, Jiaxi; Diao, Guiqiang; Liu, Jiwen; Xie, Zhuopeng; Cheng, Gao; Sun, Ming; Yu, Lin

2018-03-01

The composition of nickel cobalt sulfide has great influence on its electrochemical performance. Herein, the nickel cobalt sulfide with different composition and mixed phase were synthesized by one-step solvothermal method through changing the molar ratio of Ni to Co in the reaction system. The electrochemical measurements showed that the nickel cobalt sulfide with a theoretical molar ratio of Ni/Co to be 1.5:1.5 (NCS-2) demonstrates the superior pseudocapacitive performance with a high specific capacitance (6.47 F cm-2 at 10 mA cm-2) and a favorable Coulombic efficiency (∼99%). Whereas, when applied as the catalyst for hydrogen evolution reaction in 1 M KOH aqueous electrolyte, the nickel cobalt sulfide with a theoretical molar ratio of Ni/Co is 1:2 (NCS-1) displays better catalytic activity, and it requires a relatively lower overpotential of 282 mV to deliver the current density of 10 mA cm-2.

Computational investigation of spin-polarization in cobalt/graphite superlattices

NASA Astrophysics Data System (ADS)

Goto, Kim F.; Hill, Nicola A.; Sanvito, Stefano

2003-03-01

We present results of a computational investigation of the magnetic properties of cobalt/ graphite superlattices. This work was motivated by experimental data showing spin injection into carbon nanotubes via cobalt contacts [1] as well as the discovery of a magnetic meteorite made from graphite and magnetic particles, in which part of the magnetization is on the carbon atoms [2]. Using density functional theory within the local spin-density approximation (the SIESTA implementation), we show that cobalt induces both n-doping and a magnetic moment in the graphite layers adjacent to the cobalt-carbon interface. We also show that the magnetic properties are strongly affected by the orientation of the graphite. Finally, implications for spin injection and spin-polarized transport are discussed. [1] K. Tsukagoshi, B.W. Alphenaar, and H. Ago, Nature (London) 401, 572 (1999) [2] J.M.D. Coey, M. Venkatesan, C.B. Fitzgerald, A.P. Douvalis and I.S. Sanders, Nature (London) 420, 156 (2002)

Magnetic properties of cobalt ferrite synthesized by mechanical alloying

NASA Astrophysics Data System (ADS)

Dedi, Idayanti, Novrita; Kristiantoro, Tony; Alam, Ginanjar Fajar Nur; Sudrajat, Nanang

2018-05-01

Cobalt ferrite (CoFe2O4) is a well-known hard magnetic material with high coercivity and moderate magnetization. These properties, along with their great physical and chemical stability, make CoFe2O4 suitable for many applications such as generator, audio, video-tape etc. In this study, the magnetic properties of cobalt ferrite synthesized via the mechanical alloying using α-Fe2O3 of Hot Strip Mill (HSM) waste and cobalt carbonate as the precursors have been investigated. Structural and magnetic properties were systematically investigated. The X-ray diffraction (XRD) pattern exhibited the single phase of cobalt ferrite when the sintering temperature was 1000 °C. Permagraph measurements of the sintered sample revealed a saturation magnetization (Ms) of 77-83 emu/g and coercivity (Hc) of 575 Oe which closely to the magnetic properties of references; Ms = 47.2-56.7 emu/g and Hc =233-2002 Oe.

Effects of annealing and conformal alumina passivation on anisotropy and hysteresis of magneto-optical properties of cobalt slanted columnar thin films

NASA Astrophysics Data System (ADS)

Briley, Chad; Mock, Alyssa; Korlacki, Rafał; Hofmann, Tino; Schubert, Eva; Schubert, Mathias

2017-11-01

We present magneto-optical dielectric tensor data of cobalt and cobalt oxide slanted columnar thin films obtained by vector magneto-optical generalized ellipsometry. Room-temperature hysteresis magnetization measurements were performed in longitudinal and polar Kerr geometries on samples prior to and after a heat treatment process with and without a conformal Al2O3 passivation coating. The samples have been characterized by generalized ellipsometry, scanning electron microscopy, and Raman spectroscopy in conjuncture with density functional theory. We observe strongly anisotropic hysteresis behaviors, which depend on the nanocolumn and magnetizing field orientations. We find that deposited cobalt films that have been exposed to heat treatment and subsequent atmospheric oxidation into Co3O4, when not conformally passivated, reveal no measurable magneto-optical properties while cobalt films with passivation coatings retain highly anisotropic magneto-optical properties.

Cobalt-catalysed site-selective intra- and intermolecular dehydrogenative amination of unactivated sp3 carbons

PubMed Central

Wu, Xuesong; Yang, Ke; Zhao, Yan; Sun, Hao; Li, Guigen; Ge, Haibo

2015-01-01

Cobalt-catalysed sp2 C–H bond functionalization has attracted considerable attention in recent years because of the low cost of cobalt complexes and interesting modes of action in the process. In comparison, much less efforts have been devoted to the sp3 carbons. Here we report the cobalt-catalysed site-selective dehydrogenative cyclization of aliphatic amides via a C–H bond functionalization process on unactivated sp3 carbons with the assistance of a bidentate directing group. This method provides a straightforward synthesis of monocyclic and spiro β- or γ-lactams with good to excellent stereoselectivity and functional group tolerance. In addition, a new procedure has been developed to selectively remove the directing group, which enables the synthesis of free β- or γ-lactam compounds. Furthermore, the first cobalt-catalysed intermolecular dehydrogenative amination of unactivated sp3 carbons is also realized. PMID:25753366

Cobalt: for strength and color

USGS Publications Warehouse

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.

Battery related cobalt and REE flows in WEEE treatment.

PubMed

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

2015-11-01

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

Ferromagnetic cobalt nanocrystals achieved by soft annealing approach—From individual behavior to mesoscopic organized properties

NASA Astrophysics Data System (ADS)

Petit, C.; Wang, Z. L.; Pileni, M. P.

2007-05-01

By gentle annealing, 7 nm cobalt nanoparticles synthesized by soft chemistry, are transformed to hard magnetic hexagonal close packed (HCP) cobalt nanocrystals without changing the size, size distribution and passivating layer. This method permits to recover the nanocrystals isolated in solution after the annealing process and then to study the magnetic properties of the HCP cobalt nanocrystals at isolated status or in a self-organized film. Monolayer self-assembly of the HCP cobalt nanocrystals is obtained, and due to the dipolar interaction, ferromagnetic behavior close to room temperature has been observed. The magnetic properties differ significantly due to the influence of the substrate on the annealing process. This different approach of the annealing process of nanocrystals is compared to the classical approach of annealing in which the nanocrystals are first deposited on a substrate and then annealed.

Determination of traces of cobalt in soils: A field method

USGS Publications Warehouse

Almond, H.

1953-01-01

The growing use of geochemical prospecting methods in the search for ore deposits has led to the development of a field method for the determination of cobalt in soils. The determination is based on the fact that cobalt reacts with 2-nitroso-1-naphthol to yield a pink compound that is soluble in carbon tetrachloride. The carbon tetrachloride extract is shaken with dilute cyanide to complex interfering elements and to remove excess reagent. The cobalt content is estimated by comparing the pink color in the carbon tetrachloride with a standard series prepared from standard solutions. The cobalt 2-nitroso-1-naphtholate system in carbon tetrachloride follows Beer's law. As little as 1 p.p.m. can be determined in a 0.1-gram sample. The method is simple and fast and requires only simple equipment. More than 40 samples can be analyzed per man-day with an accuracy within 30% or better.

Application of catalytic adsorptive stripping voltammetry of the cobalt-alpha-benzil dioxime complex to analysis of cobalt traces in metallic zinc.

PubMed

Bobrowski, A

1994-05-01

The catalytic adsorptive stripping voltammetric method with alpha-benzil dioxime and nitrite affords numerous advantages in cobalt determination. The detailed conditions of the determination of the cobalt traces in metallic zinc by catalytic adsorptive stripping voltammetry have been investigated. Both the linear sweep and the differential pulse stripping modes can be used with similar sensitivity. Possible interferences by Mn, Pb, Cu, Ni and Fe are evaluated. In the presence of 5 x 10(5) fold excess of Zn the linear dependence of the cobalt CASV peak current on concentration ranged from 0.05 mug/l to 3 mug/l. Optimal conditions include the accumulation potential of -0.65 V and the accumulation time of 10 sec. The results of the determination of 10(-5)% level of Co in the metallic zinc showed good reproducibility (relative standard deviation, RSD = 0.07) and reliability.

Controlled cobalt doping in biogenic magnetite nanoparticles.

PubMed

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

2013-06-06

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

Controlled cobalt doping of magnetosomes in vivo.

PubMed

Staniland, Sarah; Williams, Wyn; Telling, Neil; Van Der Laan, Gerrit; Harrison, Andrew; Ward, Bruce

2008-03-01

Magnetotactic bacteria biomineralize iron into magnetite (Fe3O4) nanoparticles that are surrounded by lipid vesicles. These 'magnetosomes' have considerable potential for use in bio- and nanotechnological applications because of their narrow size and shape distribution and inherent biocompatibility. The ability to tailor the magnetic properties of magnetosomes by chemical doping would greatly expand these applications; however, the controlled doping of magnetosomes has so far not been achieved. Here, we report controlled in vivo cobalt doping of magnetosomes in three strains of the bacterium Magnetospirillum. The presence of cobalt increases the coercive field of the magnetosomes--that is, the field necessary to reverse their magnetization--by 36-45%, depending on the strain and the cobalt content. With elemental analysis, X-ray absorption and magnetic circular dichroism, we estimate the cobalt content to be between 0.2 and 1.4%. These findings provide an important advance in designing biologically synthesized nanoparticles with useful highly tuned magnetic properties.

Structure of catabolite activator protein with cobalt(II) and sulfate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Ramya R.; Lawson, Catherine L., E-mail: cathy.lawson@rutgers.edu

2014-04-15

The crystal structure of E. coli catabolite activator protein with bound cobalt(II) and sulfate ions at 1.97 Å resolution is reported. The crystal structure of cyclic AMP–catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcriptionmore » activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP–DNA complex structures.« less

Structural and ambient/sub-ambient temperature magnetic properties of Er-substituted cobalt-ferrites synthesized by sol-gel assisted auto-combustion method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prathapani, Sateesh; Department of Metallurgical Engineering and Materials Science, IIT-Bombay, Mumbai 400076; Jayaraman, Tanjore V., E-mail: ddas@uohyd.ernet.in, E-mail: tvjayaraman@gmail.com

2014-07-14

Er-substituted cobalt-ferrites CoFe{sub 2−x}Er{sub x}O{sub 4} (0 ≤ x ≤ 0.04) were synthesized by sol-gel assisted auto-combustion method. The precursor powders were calcined at 673–873 K for 4 h, subsequently pressed into pellets and sintered at 1273 K for 4 h. X-ray diffraction (XRD) confirmed the presence of the spinel phase for all the compositions and, additional orthoferrite phase for higher compositions (x = 0.03 and 0.04). The XRD spectra and the Transmission Electron Microscopy micrographs indicate that the nanocrystalline particulates of the Er-substituted cobalt ferrites have crystallite size of ∼120–200 nm. The magnetization curves show an increase in saturation magnetization (M{sub S}) and coercivity (H{sub C}) for Er-substituted cobalt-ferrites atmore » sub-ambient temperatures. M{sub S} for CoFe{sub 2}O{sub 4}, CoFe{sub 0.99}Er{sub 0.01}O{sub 4}, CoFe{sub 0.98}Er{sub 0.02}O{sub 4}, and CoFe{sub 0.97}Er{sub 0.03}O{sub 4} peak at 89.7 Am{sup 2}/kg, 89.3 Am{sup 2}/kg, 88.8 Am{sup 2}/kg, and 87.1 Am{sup 2}/kg, respectively, at a sub-ambient temperature of ∼150 K. H{sub C} substantially increases with decrease in temperature for all the compositions, while it peaks at x = 0.01−0.02 at all temperatures. The combination of Er content—x ∼ 0.02 and the temperature—∼5 K provides the maximum H{sub C} ∼ 984 kA/m. Er-substituted cobalt-ferrites have higher cubic anisotropy constant, K{sub 1}, compared to pure cobalt-ferrite at ambient/sub-ambient temperatures. K{sub 1} gradually increases for all compositions in the temperature decreasing from 300 to 100 K. While K{sub 1} peaks at ∼150 K for pure cobalt-ferrite, it peaks at ∼50 K for CoFe{sub 0.99}Er{sub 0.01}O{sub 4}, CoFe{sub 0.98}Er{sub 0.02}O{sub 4}, and CoFe{sub 0.96}Er{sub 0.04}O{sub 4}. The M{sub S} (∼88.7 Am{sup 2}/kg), at 5 K, for Er substituted cobalt-ferrite is close to the highest values reported for Sm and Gd substituted cobalt-ferrites. The M{sub S} (∼83.5 Am{sup 2}/kg) at 300 K for Er-substituted cobalt-ferrite is the highest among the lanthanide series element substituted cobalt-ferrites. The H{sub C} (at 5 K) for Er substituted cobalt-ferrite is close to the highest values observed for La, Ce, Nd, Sm, and Gd substituted cobalt-ferrites.« less

40 CFR 471.35 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2011 CFR

2011-07-01

... (pounds per million off-pounds) of nickel-cobalt rolled with emulsions Chromium 0.063 0.026 Nickel 0.094 0... nickel-cobalt rolled with water Chromium 0.028 0.012 Nickel 0.042 0.028 Fluoride 4.49 1.99 (d) Tube... monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt drawn with emulsions Chromium 0...

One-step separation by thermal treatment and cobalt acid-leaching from spent lithium-ion batteries

NASA Astrophysics Data System (ADS)

Mu, Deying

2017-10-01

Lithium-ion batteries are extensively used in portable storage devices and automobiles, therefore the environment and resource problems caused by spent lithium ion batteries have become increasingly severe. This paper focuses on the recovery process of spent lithium cobalt oxide active material and comes up with reasonable processes and the best conditions for cobalt leaching ultimately.

Magneto-Optic Devices Based on Organic Polymer Materials

DTIC Science & Technology

2012-09-10

cobalt  ferrite  particles...to   cobalt  ferrite  particles.     The   rings   in   the  SAED  pattern  also   indicate  averaging  of   the... cobalt  ferrite  nanoparticles  (A),  a  high   resolution  image  of  a  single  nanoparticle  showing  the

Self-assembled Tunable Photonic Hyper-crystals

DTIC Science & Technology

2014-07-16

a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to...monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing. 2 Approved for public release...assembly of photonic hyper crystals has been achieved by application of external magnetic field to a cobalt nanoparticle based ferrofluid. Unique spectral

Systems and Methods for the Electrodeposition of a Nickel-cobalt Alloy

NASA Technical Reports Server (NTRS)

Ogozalek, Nance Jo (Inventor); Wistrand, Richard E. (Inventor)

2013-01-01

Systems and methods for electrodepositing a nickel-cobalt alloy using a rotating cylinder electrode assembly with a plating surface and an electrical contact. The assembly is placed within a plating bath and rotated while running a plating cycle. Nickel-cobalt alloy deposition is selectively controlled by controlling current density distribution and/or cobalt content in the plating bath while running the plating cycle to deposit an alloy of a desired yield strength onto the plating surface in a single plating cycle. In various embodiments, the rotating cylinder may be used as an insitu monitoring method to assist in obtaining the properties desired.

Effect of the Polymeric Stabilizer in the Aqueous Phase Fischer-Tropsch Synthesis Catalyzed by Colloidal Cobalt Nanocatalysts

PubMed Central

Delgado, Jorge A.; Claver, Carmen; Castillón, Sergio; Curulla-Ferré, Daniel; Godard, Cyril

2017-01-01

A series of small and well defined cobalt nanoparticles were synthesized by the chemical reduction of cobalt salts in water using NaBH4 as a reducing agent and using various polymeric stabilizers. The obtained nanocatalysts of similar mean diameters (ca. 2.6 nm) were fully characterized and tested in the aqueous phase Fischer-Tropsch Synthesis (AFTS). Interestingly, the nature and structure of the stabilizers used during the synthesis of the CoNPs affected the reduction degree of cobalt and the B-doping of these NPs and consequently, influenced the performance of these nanocatalysts in AFTS. PMID:28336892

Ga and In modified ceria as supports for cobalt-catalyzed Fischer-Tropsch synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gnanamani, Muthu Kumaran; Jacobs, Gary; Shafer, Wilson D.

Ga- and In-modified ceria (Ce 0.8Ga 0.2O 2, Ce 0.8In 0.2O 2) materials were used as supports for cobalt-catalyzed Fischer-Tropsch synthesis (FTS). The addition of Ga to ceria was found to improve CO conversion for cobalt-catalyzed FTS, while the addition of In tended to decrease it. A similar trend was observed with the Ag-promoted cobalt/ceria catalysts. Doping of ceria with Ga or In decreased methane and increased the selectivity to olefins and alcohols for Ag-promoted cobalt/ceria. The sum of the products of olefins and alcohols for various catalysts exhibited a decreasing trend as follows: Ag-Co/Ce-Ga > Ag-Co/Ce-In > Ag-Co/Ce. Resultsmore » of H 2-TPR-XANES showed that adding of Ga or In to ceria increases the fraction of Ce 3+ in the surface shell for both unpromoted and Ag-promoted catalysts in the range of temperature typical of catalyst activation. In conclusion, this partially reduced ceria plays an important role in controlling the product selectivity of cobalt-catalyzed FT synthesis.« less

Activation of Molecular Oxygen Using Durable Cobalt Encapsulated with Nitrogen-Doped Graphitic Carbon Shells for Aerobic Oxidation of Lignin-Derived Alcohols.

PubMed

Sun, Yuxia; Ma, Hong; Luo, Yang; Zhang, Shujing; Gao, Jin; Xu, Jie

2018-03-26

It has long been a challenge for activating O 2 by transition-metal nanocatalysts, which might lose activity due to strong tendency for oxidation. Herein, O 2 could be activated by durable encapsulated cobalt nanoparticles (NPs) with N-doped graphitic carbon shells (Co@N-C), but not by encapsulated cobalt NPs with graphitic carbon, exposed cobalt NPs supported on activated carbon, or N-doped carbon. Electron paramagnetic resonance, real-time in situ FTIR spectroscopy, and mass spectrometry measurements demonstrated the generation of the highly active superoxide radical, O 2 .- . This unique ability enables Co@N-C to afford an excellent catalytic performance in model aerobic oxidation of monomeric lignin-derived alcohols. Further analysis elucidated that encapsulated cobalt and nitrogen-doped graphitic carbon might contribute to the capacity through influencing the electronic properties of outer layers. Moreover, through isolation by N-doped graphitic carbon shells, the inner metallic cobalt NPs are inaccessible in term of either alcohols or oxygenated products, and a distinctive resistance to leaching and agglomeration has been achieved. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Systematic Doping of Cobalt into Layered Manganese Oxide Sheets Substantially Enhances Water Oxidation Catalysis.

PubMed

McKendry, Ian G; Thenuwara, Akila C; Shumlas, Samantha L; Peng, Haowei; Aulin, Yaroslav V; Chinnam, Parameswara Rao; Borguet, Eric; Strongin, Daniel R; Zdilla, Michael J

2018-01-16

The effect on the electrocatalytic oxygen evolution reaction (OER) of cobalt incorporation into the metal oxide sheets of the layered manganese oxide birnessite was investigated. Birnessite and cobalt-doped birnessite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and conductivity measurements. A cobalt:manganese ratio of 1:2 resulted in the most active catalyst for the OER. In particular, the overpotential (η) for the OER was 420 mV, significantly lower than the η = 780 mV associated with birnessite in the absence of Co. Furthermore, the Tafel slope for Co/birnessite was 81 mV/dec, in comparison to a Tafel slope of greater than 200 mV/dec for birnessite. For chemical water oxidation catalysis, an 8-fold turnover number (TON) was achieved (h = 70 mmol of O 2 /mol of metal). Density functional theory (DFT) calculations predict that cobalt modification of birnessite resulted in a raising of the valence band edge and occupation of that edge by holes with enhanced mobility during catalysis. Inclusion of extra cobalt beyond the ideal 1:2 ratio was detrimental to catalysis due to disruption of the layered structure of the birnessite phase.

Ga and In modified ceria as supports for cobalt-catalyzed Fischer-Tropsch synthesis

DOE PAGES

Gnanamani, Muthu Kumaran; Jacobs, Gary; Shafer, Wilson D.; ...

2017-08-24

Ga- and In-modified ceria (Ce 0.8Ga 0.2O 2, Ce 0.8In 0.2O 2) materials were used as supports for cobalt-catalyzed Fischer-Tropsch synthesis (FTS). The addition of Ga to ceria was found to improve CO conversion for cobalt-catalyzed FTS, while the addition of In tended to decrease it. A similar trend was observed with the Ag-promoted cobalt/ceria catalysts. Doping of ceria with Ga or In decreased methane and increased the selectivity to olefins and alcohols for Ag-promoted cobalt/ceria. The sum of the products of olefins and alcohols for various catalysts exhibited a decreasing trend as follows: Ag-Co/Ce-Ga > Ag-Co/Ce-In > Ag-Co/Ce. Resultsmore » of H 2-TPR-XANES showed that adding of Ga or In to ceria increases the fraction of Ce 3+ in the surface shell for both unpromoted and Ag-promoted catalysts in the range of temperature typical of catalyst activation. In conclusion, this partially reduced ceria plays an important role in controlling the product selectivity of cobalt-catalyzed FT synthesis.« less

The effect of cobalt and carbon the microstructure and mechanical properties of martensitic precipitation strengthened stainless steels

NASA Astrophysics Data System (ADS)

Komolwit, Piyamanee

The effects of cobalt additions on the mechanical properties and strengthening mechanisms of a martensitic precipitation strengthening stainless steel whose composition is (in wt. %) 0.005C/12Cr/5Mo/1.5Ni has been investigated for cobalt levels of 9, 12, 15, 18, and 21 wt. %. Hardness, yield strength and ultimate tensile strength increase as the cobalt content increases, while the Charpy impact energy decreases as tempering temperature increases. At the peak strength of the 21 wt. % cobalt alloy, which is after tempering at 550°C, the yield strength is 1772 MPa, the ultimate tensile strength is 1916 MPa, and the hardness is 55 HRC. The martensite start temperature decreases as cobalt content increases. In this alloys there is no retained austenite after austenitizing, oil quenching and then refrigerating in liquid nitrogen prior to tempering. These alloys contain no reverted austenite except for the 21 wt. % cobalt alloy after tempering at 600°C. Optical micrographs show lath martensite as the matrix for all alloys. Increasing cobalt content has little effect on prior austenite grain size. Transmission electron micrographs show a substructure of lath martensite and a b.c.c. matrix for all alloys after tempering at 525°C. Precipitates were observed in dark field images at all cobalt levels and were seen in bright field images of 21 wt. % cobalt alloy. One of the precipitates was identified as omega phase with a trigonal structure with lattice parameter of a = b = 4.1 A, c = 2.51 A with c/a = 0.612. The particle size appears to be 17 nanometers in diameter and they were found only in the foils of 21 wt. % cobalt alloy. The second precipitate type was identified as a monoclinic phase with a monoclinic structure with lattice parameters of a = 5.464 A, b = 2.843 A, c = 3.178 A, and alpha = gamma = 90° and beta = 63.4°. The monoclinic phase particles appear to significantly contribute to the strength of these alloys, with particles size and volume fraction increasing with increasing cobalt content for the same condition. Limited observation on the effects of carbon additions to a 12Cr/12Co/5Mo/4.5Ni martensitic precipitation strengthening stainless steel has been made for carbon levels of 0.005 wt. %, 0.025 wt. % and 0.05 wt. %. A small addition of chromium, one weight percent, to a 0.005C/12Co/5Mo/5Ni martensitic precipitation strengthening stainless steel was found to increase hardness, strength, Charpy impact energy, and ductility. Results on the effects of cobalt, carbon and chromium additions helped in the selection of modified alloys which were used to investigate the effects of composition and heat treatment on strength and toughness. The first set of modified alloys are referred to as the low carbon modified alloys. These alloys have a better Charpy impact energy than the alloys used to investigate the effect of cobalt on strength and the hardness and strength of these alloys are similar to those of alloys used to investigate the effects of cobalt on strength. Fractographs of these alloys show quasi-cleavage fracture, the presence of ductile fracture increases with increasing cobalt content. The martensite start temperature is lowered by the chromium additions and results in the existence of retained austenite even after refrigeration after austenitizing. Refrigeration prior to tempering is not necessary for these alloys to achieve a high yield strength and good Charpy impact energy. The second set of modified alloys are referred to as the carbon-titanium modified alloys. These alloys differ from the first set of modified alloys in that these alloys contain small additions of carbon and titanium and have lower cobalt levels. Lower cobalt levels were required because carbon lowers the martensite start temperature. These alloys have improved Charpy impact energy and ductility. The carbon addition lowers the martensite start temperature and the martensite start temperature of these alloys is sufficiently low that they contain retain austenite even after refrigeration after austenitizing. Refrigeration prior to tempering is necessity for the alloys to maintain their yield strength and hardness. The effects of austenitizing temperature, cooling rate after austenitization, refrigeration and double austenitization on the mechanical properties of the modified alloys were investigated. Lowering the austenitization temperature decreases the Charpy impact energy and hardness of these alloys. (Abstract shortened by UMI.)

Controlled synthesis of Co2C nanochains using cobalt laurate as precursor: Structure, growth mechanism and magnetic properties

NASA Astrophysics Data System (ADS)

Zhang, Yajing; Zhu, Yuan; Wang, Kangjun; Li, Da; Wang, Dongping; Ding, Fu; Meng, Dan; Wang, Xiaolei; Choi, Chuljin; Zhang, Zhidong

2018-06-01

Cobalt carbides (Co2C and Co3C) nanocomposites exhibit interesting hard magnetic property, controlled synthesis of individual phase facilitates to clarify the magnetism of each, but it is difficult to obtain the single phase. We present a new approach to address this issue via a polyol refluxing process, using cobalt laurate as the precursor. The single phase Co2C magnetic nanochains self-assembled by nanoparticles are synthesized. The precursor is the key factor for controlling the growth kinetics of the Co2C nanochains. Cobalt, instead of cobalt carbides, is produced if cobalt chloride, acetate and acetylacetonate replace cobalt laurate as the precursor, respectively. The evolution of the growth process has been studied. In the formation of Co2C, first fcc-Co produces, then it transforms into Co2C by carbon diffusion process, and the produced carbon first exists in disordered state and then a small amount of them transforms into graphite. Saturation magnetization (Ms) of Co2C nanochains obtained at 300 °C for 20, 60, and 180 min are 27.1, 18.9, and 10.9 emu g-1, respectively. The decrease of Ms caused by increasing carbon content, and the carbon content are much larger than the stoichiometric ratio value of Co2C (9.2 wt%). The Co2C nanochains have mesoporous pore of 3.8 nm and the specific surface area of 48.6 m2 g-1.

Hypoxia-mimicking bioactive glass regenerative effects on dental stem cells

NASA Astrophysics Data System (ADS)

Noor, Siti Noor Fazliah Mohd; Azevedo, Maria; Mohamad, Hasmaliza; Autefage, Hélène

2016-12-01

Vascularization is an important aspect of tissue regeneration. Hypoxia, low oxygen concentration, is a known stimulus for the release of vascular endothelial growth factors (VEGF) which play important roles in vascularization. The current study aimed to assess the effect of a cobalt-containing bioactive glass (BG) in stimulating hypoxia and promoting vascularization. To incorporate cobalt into BG, 1 mol% of calcium was substituting with cobalt, and this formulation was compared to the one without cobalt. Both BGs were processed via melt-derived method. The BG powders with particle size less than 38 µm were incubated with cell culture medium for 4 hours at 37°C on continuous rolling, and then the medium was filtered using 0.22 µm syringe filters. Prior to use, the BG-conditioned media were supplemented with 10% (v/v) fetal bovine serum and 1% (v/v) antibiotic-antimycotic, and were allowed to equilibrate overnight inside a CO2 incubator. The conditioned media were used on human dental stem cells (stem cells from permanent (DPSC) and deciduous (SHED) teeth) and assessed for their capacity to stimulate the release of angiogenic factors from the cells. The results showed that cobalt ions were released from the cobalt-containing BG, following partial dissolution of the glasses in cell culture medium, and promoted VEGF release from the cells. In conclusion, the incorporation of cobalt in BG may have potential to be used for tissue regeneration by promoting vascularization through the activation of hypoxia pathway and the release of VEGF.

Design of organic dyes and cobalt polypyridine redox mediators for high-efficiency dye-sensitized solar cells.

PubMed

Feldt, Sandra M; Gibson, Elizabeth A; Gabrielsson, Erik; Sun, Licheng; Boschloo, Gerrit; Hagfeldt, Anders

2010-11-24

Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO(2) films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2'-bipyridyl)cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m(-2) AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.

Magnetic cobaltic nanoparticle-anchored carbon nanocomposite derived from cobalt-dipicolinic acid coordination polymer: An enhanced catalyst for environmental oxidative and reductive reactions.

PubMed

Wu, Chang-Hsun; Lin, Jyun-Ting; Lin, Kun-Yi Andrew

2018-05-01

Direct carbonization of cobalt complexes represents as a convenient approach to prepare magnetic carbon/cobalt nanocomposites (MCCNs) as heterogeneous environmental catalysts. However, most of MCCNs derived from consist of sheet-like carbon matrices with very sparse cobaltic nanoparticles (NPs), making them exhibit relatively low catalytic activities, porosity and magnetism. In this study, dipicolinic acid (DPA) is selected to prepare a 3-dimensional cobalt coordination polymer (CoDPA). MCCN derived from CoDPA can consist of a porous carbon matrix embedded with highly-dense Co 0 and Co 3 O 4 NPs. This magnetic Co 0 /Co 3 O 4 NP-anchored carbon composite (MCNC) appears as a promising heterogeneous catalyst for oxidative and reductive environmental catalytic reactions. As peroxymonosulfate (PMS) activation is selected as a model catalytic oxidative reaction, MCNC exhibits a much higher catalytic activity than Co 3 O 4 , a benchmark catalyst for PMS activation. The reductive catalytic activity of MCNC is demonstrated through 4-nitrophenol (4-NP) reduction in the presence of NaBH 4 . MCNC could rapidly react with NaBH 4 to generate H 2 for hydrogenation of 4-NP to 4-aminophenol (4-AP). In comparison with other precious metallic catalysts, MCNC also shows a relatively high catalytic activity. These results indicate that MCNC is a conveniently prepared and highly effective and stable carbon-supported cobaltic heterogeneous catalyst for versatile environmental catalytic applications. Copyright © 2018 Elsevier Inc. All rights reserved.

A New Type of Metal-Binding Site in Cobalt- And Zinc-Containing Adenylate Kinases Isolated From Sulfate-Reducers D. Gigas And D. Desulfuricans ATCC 27774

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavel, O.Y.; Bursakov, S.A.; Rocco, G.Di

2009-05-18

Adenylate kinase (AK) mediates the reversible transfer of phosphate groups between the adenylate nucleotides and contributes to the maintenance of their constant cellular level, necessary for energy metabolism and nucleic acid synthesis. The AK were purified from crude extracts of two sulfate-reducing bacteria (SRB), Desulfovibrio (D.) gigas NCIB 9332 and Desulfovibrio desulfuricans ATCC 27774, and biochemically and spectroscopically characterized in the native and fully cobalt- or zinc-substituted forms. These are the first reported adenylate kinases that bind either zinc or cobalt and are related to the subgroup of metal-containing AK found, in most cases, in Gram-positive bacteria. The electronic absorptionmore » spectrum is consistent with tetrahedral coordinated cobalt, predominantly via sulfur ligands, and is supported by EPR. The involvement of three cysteines in cobalt or zinc coordination was confirmed by chemical methods. Extended X-ray absorption fine structure (EXAFS) indicate that cobalt or zinc are bound by three cysteine residues and one histidine in the metal-binding site of the 'LID' domain. The sequence {sup 129}Cys-X{sub 5}-His-X{sub 15}-Cys-X{sub 2}-Cys of the AK from D. gigas is involved in metal coordination and represents a new type of binding motif that differs from other known zinc-binding sites of AK. Cobalt and zinc play a structural role in stabilizing the LID domain.« less

Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. Themore » results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.« less

Comparison of Uninjured and Concussed Adolecent Athletes on the Concussion Balance Test (COBALT).

PubMed

Massingale, Shelly; Alexander, Amy; Erickson, Steven; McQueary, Elizabeth; Gerkin, Richard; Kisana, Haroon; Silvestri, Briana; Schodrof, Sarah; Nalepa, Bryce; Pardini, Jamie

2018-06-01

Dizziness and balance problems are common symptoms following sports-related concussion (SRC). Most sports require high-level balance skills that integrate the sensory inputs used for balance. Thus, a comprehensive assessment of postural control following SRC is recommended as an integral part of evaluation and management of the injury. The purpose of this exploratory study was to examine performance differences between uninjured and concussed athletes on the Concussion Balance Test (COBALT), as well as complete preliminary analyses of criterion-related validity and reliability of COBALT. COBALT is an 8 condition test developed for both preseason and postinjury assessment using force plate technology to measure sway velocity under dynamic postural conditions that challenge the vestibular system. Retrospective COBALT data obtained through chart review for 132 uninjured athletes and 106 concussed age-matched athletes were compared. All uninjured athletes were able to complete the assessment, compared with only 55% of concussed athletes. Concussed athletes committed significantly more errors than uninjured athletes. Sway velocity for concussed athletes was higher (worse) than that for uninjured athletes on 2 conditions in COBALT. By examining an athlete's ability to complete the protocol, error rate, and sway velocity on COBALT postinjury, the clinician can identify balance function impairment, which may help the medical team develop a more targeted treatment plan, and provide objective input regarding recovery of balance function following SRC.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A204).

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

NASA Technical Reports Server (NTRS)

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.

Characterization of the Unusual Product from the Reaction between Cobalt(II) Chloride, Ethane-1,2-diamine, and Hydrochloric Acid: An Undergraduate Project Involving an Unknown Metal Complex.

ERIC Educational Resources Information Center

Curtis, Neil F.; And Others

1986-01-01

Discusses the need for student research-type chemistry projects based upon "unknown" metal complexes. Describes an experiment involving the product from the reaction between cobalt(II) chloride, ethane-1,2-diamine (en) and concentrated hydrochloric acid. Outlines the preparation of the cobalt complex, along with procedure, results and…

Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative

DTIC Science & Technology

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...coatings as a Hard Chrome (EHC) electroplating alternative for DoD manufacturing and repair. – Fully define deposition parameters and properties

SU-E-T-328: Dosimetric Impact of Cobalt-Chrome Stabilization Hardware in Paraspinal Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, G; LoSasso, T; Saleh, Z

2015-06-15

Purpose: Due to saturation, high density materials Result in an apparent density of 3.2 g/cm{sup 3} in CT images. The true density of traditional titanium stabilization rods (∼4.4 g/cm{sup 3}) is typically ignored in treatment planning. This may not be acceptable for new cobalt-chrome rods with a density of 8.5 g/cm{sup 3}. This study reports the dosimetric impact of cobalt-chrome rods in paraspinal radiotherapy. Methods: For titanium and cobalt-chrome rods, two planning studies were done for both IMRT and VMAT in Varian Eclipse using AAA. 1) The effect of planning without assigning the true rod density was assessed by comparingmore » plans generated with the apparent density and recalculated with the true density for titanium and cobalt-chrome. 2) To test if TPS can compensate for high density rods during optimization. Furthermore, TPS calculation accuracy was verified using MapCheck for a single 20 x 10 cm{sup 2} field. The MapCheck was incrementally shifted to achieve measurement resolution of 1 mm. Results: PTV coverage was ∼0.3% and ∼4.7% lower in plans that were recalculated with the true rod density of titanium and cobalt-chrome, respectively. PTV coverage can be maintained if the correct density is used in optimization. Measurements showed that TPS overestimated the dose locally by up to 11% for cobalt-chrome rods and up to 4% for titanium rods if the density is incorrect. With density corrected, maximum local differences of 6% and 3% were seen for cobalt-chrome and titanium rods, respectively. At 2 cm beneath a rod, electrons scattered from the side of the rod increased the lateral dose and diminished as depth increases. TPS was not able to account for this effect properly even with the true rod density assigned. Conclusion: Neglecting the true density of cobalt-chrome rods can cause under coverage to the PTV. Assigning the correct density during treatment planning can minimize unexpected decrease in PTV dose.« less

[Lead adsorption and arsenite oxidation by cobalt doped birnessite].

PubMed

Yin, Hui; Feng, Xiong-Han; Qiu, Guo-Hong; Tan, Wen-Feng; Liu, Fan

2011-07-01

In order to study the effects of transition metal ions on the physic-chemical properties of manganese dioxides as environmental friendly materials, three-dimensional nano-microsphere cobalt-doped birnessite was synthesized by reduction of potassium permanganate by mixtures of concentrated hydrochloride and cobalt (II) chloride. Powder X-ray diffraction, chemical analysis, N2 physical adsorption, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectra (XPS) were used to characterize the crystal structure, chemical composition and micro-morphologies of products. In the range of molar ratios from 0.05 to 0.20, birnessite was fabricated exclusively. It was observed that cobalt incorporated into the layers of birnessite and had little effect on the crystal structure and micromorpholgy, but crystallinity decreased after cobalt doping. Both chemical analysis and XPS results showed that manganese average oxidation state decreased after cobalt doping, and the percentage of Mn3+ increased. Co(III) OOH existed mainly in the structure. With the increase of cobalt, hydroxide oxygen percentage in molar increased from 12.79% for undoped birnessite to 13.05%, 17.69% and 17.79% for doped samples respectively. Adsorption capacity for lead and oxidation of arsenite of birnessite were enhanced by cobalt doping. The maximum capacity of Pb2+ adsorption increased in the order HB (2 538 mmol/kg) < CoB5 (2798 mmol/kg) < CoB10 (2932 mmol/kg) < CoB20 (3 146 mmol/kg). Oxidation percentage of arsenite in simulated waste water by undoped birnessite was 76.5%, those of doped ones increased by 2.0%, 12.8% and 18.9% respectively. Partial of Co3+ substitution for Mn4+ results in the increase of negative charge of the layer and the content of hydroxyl group, which could account for the improved adsorption capacity of Pb2+. After substitution of manganese by cobalt, oxidation capacity of arsenite by birnessite increases likely due to the higher standard redox potential of Co3+/Co2+ than those of Mn4+/Mn3+/Mn2+. Therefore, Co-doped birnessite is more applicable for the remediation of water polluted with heavy metal ions, implying new methods of modification of manganese dioxides in practice.

Intercalation of Cobalt into the Interlayer of Birnessite Improves Oxygen Evolution Catalysis

DOE PAGES

Thenuwara, Akila C.; Shumlas, Samantha L.; Attanayake, Nuwan H.; ...

2016-10-10

Here we show that the activity of cobalt for the oxygen evolution reaction (OER) can be enhanced by confining it in the interlayer region of birnessite (layered manganese oxide). The cobalt intercalation was verified by employing state-of-the-art characterization techniques such as XRD, Raman and electron microscopy. It is demonstrated that the Co 2+/birnessite electrocatalyst can reach 10 mA cm -2 at an overpotential of 360 mV with near unity Faradaic efficiency. This overpotential is lower than that which can be achieved by using a pure cobalt hydroxide electrocatalyst for the OER. Furthermore, the Co 2+/birnessite catalyst shows no degradation aftermore » 1000 electrochemical cycles.« less

Hepatic lipidosis associated with cobalt deficiency in Omani goats.

PubMed

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

1999-06-01

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

Magnetic and resonance properties of ferrihydrite nanoparticles doped with cobalt

NASA Astrophysics Data System (ADS)

Stolyar, S. V.; Yaroslavtsev, R. N.; Iskhakov, R. S.; Bayukov, O. A.; Balaev, D. A.; Dubrovskii, A. A.; Krasikov, A. A.; Ladygina, V. P.; Vorotynov, A. M.; Volochaev, M. N.

2017-03-01

Powders of undoped ferrihydrite nanoparticles and ferrihydrite nanoparticles doped with cobalt in the ratio of 5: 1 have been prepared by hydrolysis of 3 d-metal salts. It has been shown using Mössbauer spectroscopy that cobalt is uniformly distributed over characteristic crystal-chemical positions of iron ions. The blocking temperatures of ferrihydrite nanoparticles have been determined. The nanoparticle sizes, magnetizations, surface anisotropy constants, and bulk anisotropy constants have been estimated. The doping of ferrihydrite nanoparticles with cobalt leads to a significant increase in the anisotropy constant of a nanoparticle and to the formation of surface rotational anisotropy with the surface anisotropy constant K u = 1.6 × 10-3 erg/cm2.

Characterization of cobalt(II) chloride-modified condensation polyimide films

NASA Technical Reports Server (NTRS)

Rancourt, J. D.; Taylor, L. T.

1988-01-01

The effect of solvent extraction on the properties of cobalt(II) chloride-modified polyimide films was investigated. Solvent-cast films were prepared from solutions of cobalt chloride in poly(amide acid)/N,N-dimethylacetamide (DMAc) and were subsequently dried and cured in static air, forced air, or inert gas ovens with controlled humidity. The films were extracted by either of the three processes (1) soaking in a tray with distilled water at room temperature, (2) soxhlett extraction with distilled water, or (3) soxhell extraction with DMAc. Extraction with DMAc was found to remove both cobalt and chlorine from the films and to slightly increase bulk thermal stability and both surface resistivity and electrical resistivity.

Cobalt spin states and hyperfine interactions in LaCoO3 investigated by LDA+U calculations

NASA Astrophysics Data System (ADS)

Hsu, Han; Blaha, Peter; Wentzcovitch, Renata M.; Leighton, C.

2010-09-01

With a series of local-density approximation plus Hubbard U calculations, we have demonstrated that for lanthanum cobaltite (LaCoO3) , the electric field gradient at the cobalt nucleus can be used as a fingerprint to identify the spin state of the cobalt ion. Therefore, in principle, the spin state of the cobalt ion can be unambiguously determined from nuclear magnetic resonance spectra. Our calculations also suggest that a crossover from the low-spin to intermediate-spin state in the temperature range of 0-90 K is unlikely, based on the half-metallic band structure associated with isolated IS Co ions, which is incompatible with the measured conductivity.

Intercalating cobalt between graphene and iridium (111): Spatially dependent kinetics from the edges

NASA Astrophysics Data System (ADS)

Vlaic, Sergio; Rougemaille, Nicolas; Kimouche, Amina; Burgos, Benito Santos; Locatelli, Andrea; Coraux, Johann

2017-10-01

Using low-energy electron microscopy, we image in real time the intercalation of a cobalt monolayer between graphene and the (111) surface of iridium. Our measurements reveal that the edges of a graphene flake represent an energy barrier to intercalation. Based on a simple description of the growth kinetics, we estimate this energy barrier and find small, but substantial, local variations. These local variations suggest a possible influence of the graphene orientation with respect to its substrate and of the graphene edge termination on the energy value of the barrier height. Besides, our measurements show that intercalated cobalt is energetically more favorable than cobalt on bare iridium, indicating a surfactant role of graphene.

Electrocatalytic behaviour of surface confined pentanethio cobalt (II) binuclear phthalocyanines towards the oxidation of 4-chlorophenol

NASA Astrophysics Data System (ADS)

Makinde, Zainab O.; Louzada, Marcel; Mashazi, Philani; Nyokong, Tebello; Khene, Samson

2017-12-01

Cobalt binuclear phthalocyanine (CoBiPc) bearing pentanethio substituents at the peripheral positions were synthesized. The immobilization of the synthesized cobalt phthalocyanines on gold electrode was achieved using self-assembled monolayer method (SAM). X-ray photoelectron spectroscopy (XPS) and Kelvin Probe (KP) techniques were used to characterise the formation of monomeric and binuclear phthalocyanine SAMs on the gold surface. The phthalocyanine SAMs on gold electrodes were investigated for electrocatalytic oxidation of 4-chlorophenol. The electrocatalytic properties of tetra- and octa- pentanethio substituted cobalt binuclear phthalocyanine (CoBiPc) are compared with their tetra- and octa-pentanethio substituted phthalocyanine (CoPc). The SAMs modified gold electrode surfaces showed a peak current enhancement and stability and reduction in electrocatalytic potentials compared to the bare or unmodified electrodes towards the detection of the 4-chlorophenol. The SAMs of cobalt binuclear phthalocyanines exhibited more enhanced electrocatalytic properties in terms of stability, detection peak current and reduction of the electrocatalytic over potential.

Interfacial microanalysis of rubber tyre-cord adhesion and the influence of cobalt

NASA Astrophysics Data System (ADS)

Fulton, W. Stephen; Smith, Graham C.; Titchener, Keith J.

2004-01-01

The effect of cobalt-containing adhesion promoters on the structure and morphology of rubber-brass and rubber-tyre-cord interfaces before and after ageing has been investigated by X-ray photoelectron spectroscopy (XPS) depth profiling, glancing incidence X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect the cobalt adhesion promoters had upon the interface morphology as they suppressed the growth of crystalline dendrites normally associated with the ageing process was imaged in TEM using samples prepared by the focused ion beam (FIB) milling technique. XPS depth profiling through the interfaces revealed that different types of adhesion promoter influenced the amount and distribution of cobalt ions in the bonding layer. XRD demonstrated the influence that cobalt had upon the structure of the interface and subsequent crystallinity, with a lesser degree of crystallinity being associated with better adhesion performance. From the results a model for the effect of the Co chemistry of the adhesion promotor has been developed.

Microstructural and optical properties of Ca and Cr doped cobalt ferrite nanoparticles synthesized by auto combustion

NASA Astrophysics Data System (ADS)

Agrawal, Shraddha; Parveen, Azra; Azam, Ameer

2018-05-01

The Ca and Cr doped cobalt ferrite nanoparticles (Co0.8Ca0.2) (Fe0.8 Cr0.2)2O4 were synthesized by auto combustion method. Microstructural studies were carried out by X-ray diffraction (XRD). The crystalline size of synthesized nanoparticles as determined by the XRD was found to be 17.6 nm. These structural studies suggest that the crystal system remains spinal even with the doping of calcium and chromium. Optical properties of Ca and Cr doped cobalt ferrite were studied by UV-visible technique in the range of 200-800 nm. The energy band gap was calculated with the help of Tauc relationship. Ca and Cr doped cobalt ferrite annealed at 600°C exhibit significant dispersion in complex permeability. The dielectric constant and dielectric loss of cobalt ferrite were studied as a function of frequency and were explained on the basis of Koop's theory based on Maxwell Wagner two layer models and electron hopping.

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

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Synthesis, characterization and oxidation of metallic cobalt (Co) thin film into semiconducting cobalt oxide (Co3O4)thin film using microwave plasma CVD

NASA Astrophysics Data System (ADS)

Rahman Ansari, Akhalakur; Hussain, Shahir; Imran, Mohd; Abdel-wahab, M. Sh; Alshahrie, Ahmed

2018-06-01

The pure cobalt thin film was deposited on the glass substrate by using DC magnetron sputtering and then exposed to microwave assist oxygen plasma generated in microwave plasma CVD. The oxidation process of Co thin film into Co3O4 thin films with different microwave power and temperature were studied. The influences of microwave power, temperature and irradiation time were investigated on the morphology and particle size of oxide thin films. The crystal structure, chemical conformation, morphologies and optical properties of oxidized Co thin films (Co3O4) were studied by using x-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Raman Spectroscopy and UV–vis Spectroscopy. The data of these films showed complete oxidation pure metallic cobalt (Co) into cobalt oxide (Co3O4). The optical properties were studied for calculating the direct band gaps which ranges from 1.35 to 1.8 eV.

An efficient molybdenum disulfide/cobalt diselenide hybrid catalyst for electrochemical hydrogen generation

PubMed Central

Gao, Min-Rui; Liang, Jin-Xia; Zheng, Ya-Rong; Xu, Yun-Fei; Jiang, Jun; Gao, Qiang; Li, Jun; Yu, Shu-Hong

2015-01-01

The electroreduction of water for sustainable hydrogen production is a critical component of several developing clean-energy technologies, such as water splitting and fuel cells. However, finding a cheap and efficient alternative catalyst to replace currently used platinum-based catalysts is still a prerequisite for the commercialization of these technologies. Here we report a robust and highly active catalyst for hydrogen evolution reaction that is constructed by in situ growth of molybdenum disulfide on the surface of cobalt diselenide. In acidic media, the molybdenum disulfide/cobalt diselenide catalyst exhibits fast hydrogen evolution kinetics with onset potential of −11 mV and Tafel slope of 36 mV per decade, which is the best among the non-noble metal hydrogen evolution catalysts and even approaches to the commercial platinum/carbon catalyst. The high hydrogen evolution activity of molybdenum disulfide/cobalt diselenide hybrid is likely due to the electrocatalytic synergistic effects between hydrogen evolution-active molybdenum disulfide and cobalt diselenide materials and the much increased catalytic sites. PMID:25585911

Hydrothermal-electrochemical growth of heterogeneous ZnO: Co films

NASA Astrophysics Data System (ADS)

Yilmaz, Ceren; Unal, Ugur

2017-10-01

This study demonstrates the preparation of heterogeneous ZnO: Co nanostructures via hydrothermal-electrochemical deposition at 130 °C and -1.1 V (vs Ag/AgCl (satd)) in dimethyl sulfoxide (DMSO)-H2O mixture. Under the stated conditions, ZnO: Co nanostructures grow preferentially along (002) direction. Strength of directional growth progressively increases with the increasing concentration of Co(II) in the deposition bath. Films are composed of hexagonal Wurtzite ZnO, metallic cobalt, and mixed cobalt oxide on the surface and cobalt(II) oxide in deeper levels. Increasing the Co(II) concentration in the deposition bath results in different morphological features as well as phase separation. Platelets, sponge-like structures, cobalt-rich spheres, microislands of cobalt-rich spheres which are interconnected by ZnO network can be synthesized by adjusting [Co(II)]: [Zn(II)] ratio. Growth mechanisms giving rise to these particular structures, surface morphology, crystal structure, phase purity, chemical binding characteristics, and optical properties of the deposits are discussed in detail.

[Fluorescence Resonance Energy Transfer Detection of Cobalt Ions by Silver Triangular Nanoplates and Rhodamine 6G].

PubMed

Zhang, Xiu-qing; Peng, Jun; Ling, Jian; Liu, Chao-juan; Cao, Qiu-e; Ding, Zhong-tao

2015-04-01

In the present paper, the authors studied fluorescence resonance energy transfer (FRET) phenomenon between silver triangular nanoplates and bovine serum albumin (BSA)/Rhodamine 6G fluorescence complex, and established a fluorescence method for the detection of cobalt ions. We found that when increasing the silver triangular nanoplates added to certain concentrations of fluorescent bovine serum albumin (BSA)/Rhodamine 6G complex, the fluorescence of Rhodamine 6G would be quenched up to 80% due to the FRET between the quencher and donor. However, in the presence of cobalt ions, the disassociation of the fluorescent complex from silver triangular nanoplates occurred and the fluorescence of the Rhodamine 6G recovered. The recovery of fluorescence intensity rate (I/I0) has a good relationship with the cobalt ion concentration (cCO2+) added. Thus, the authors developed a fluorescence method for the detection of cobalt ions based on the FRET of silver triangular nanoplates and Rhodamine 6G.

Synthesis of Some "Cobaloxime" Derivatives: A Demonstration of "Umpolung" in the Reactivity of an Organometallic Complex

NASA Astrophysics Data System (ADS)

Jameson, Donald L.; Grzybowski, Joseph J.; Hammels, Deb E.; Castellano, Ronald K.; Hoke, Molly E.; Freed, Kimberly; Basquill, Sean; Mendel, Angela; Shoemaker, William J.

1998-04-01

This article describes a four-reaction sequence for the synthesis of two organometallic "cobaloxime" derivatives. The concept of "Umpolung" or reversal of reactivity is demonstrated in the preparation of complexes. The complex Co(dmgH)2(4-t-BuPy)Et is formed by the reaction of a cobalt (I) intermediate (cobalt in the role of nucleophile) with ethyl iodide. The complex Co(dmgH)2(4-t-BuPy)Ph is formed by the reaction of PhMgBr with a cobalt (III) intermediate (cobalt in the role of electrophile). All the products contain cobalt in the diamagnetic +3 oxidation state and are readily characterized by proton and carbon NMR. The four reaction sequence may be completed in two 4-hour lab periods. Cobaloximes are well known as model complexes for Vitamin B-12 and the experiment exposes students to aspects of classical coordination chemistry, organometallic chemistry and bioinorganic chemistry. The experiment also illustrates an important reactivity parallel between organic and organometallic chemistry.

Influence of Cobalt on the Properties of Load-Sensitive Magnesium Alloys

PubMed Central

Klose, Christian; Demminger, Christian; Mroz, Gregor; Reimche, Wilfried; Bach, Friedrich-Wilhelm; Maier, Hans Jürgen; Kerber, Kai

2013-01-01

In this study, magnesium is alloyed with varying amounts of the ferromagnetic alloying element cobalt in order to obtain lightweight load-sensitive materials with sensory properties which allow an online-monitoring of mechanical forces applied to components made from Mg-Co alloys. An optimized casting process with the use of extruded Mg-Co powder rods is utilized which enables the production of magnetic magnesium alloys with a reproducible Co concentration. The efficiency of the casting process is confirmed by SEM analyses. Microstructures and Co-rich precipitations of various Mg-Co alloys are investigated by means of EDS and XRD analyses. The Mg-Co alloys' mechanical strengths are determined by tensile tests. Magnetic properties of the Mg-Co sensor alloys depending on the cobalt content and the acting mechanical load are measured utilizing the harmonic analysis of eddy-current signals. Within the scope of this work, the influence of the element cobalt on magnesium is investigated in detail and an optimal cobalt concentration is defined based on the performed examinations. PMID:23344376

Novel synthesis of cobalt/poly vinyl alcohol/gamma alumina nanocomposite for catalytic application

NASA Astrophysics Data System (ADS)

Hatamie, Shadie; Ahadian, Mohammad Mahdi; Rashidi, Alimoradeh; Karimi, Ali; Akhavan, Omid

2017-05-01

In this manuscript, synthesis of cobalt/poly vinyl alcohol (PVA)/gamma alumina nanocomposite via a simple room temperature, as well as its catalyst performance were explored. Brunauer-Emmett-Teller analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were conducted. The surface area of the polymeric composite was obtained to be 280 m2/g. The cobalt loading on the nanocomposite was measured using inductivity couple plasma. Transmission electron microscopy analysis showed that the size of cobalt crystalline encapsulate inside the polymer was confined to 5 nm. Magnetic property analysis, using vibrating sample magnetometer, confirmed ferromagnetic nature of the composite. Thermo-gravimetric analyses were employed to explain the degradation process for the polymeric base nanocomposite. Temperature-programmed reduction was used to evaluate the structural form of cobalt oxide in nanocomposite. The catalysis activity was determined by Fischer-Tropsch synthesize, which showed a high catalyst selectivity to C2-C4 hydrocarbons.

Carbon-encapsulated nickel-cobalt alloys nanoparticles fabricated via new post-treatment strategy for hydrogen evolution in alkaline media

NASA Astrophysics Data System (ADS)

Guo, Hailing; Youliwasi, Nuerguli; Zhao, Lei; Chai, Yongming; Liu, Chenguang

2018-03-01

This paper addresses a new post-treatment strategy for the formation of carbon-encapsulated nickel-cobalt alloys nanoparticles, which is easily controlled the performance of target products via changing precursor composition, calcination conditions (e.g., temperature and atmosphere) and post-treatment condition. Glassy carbon electrode (GCE) modified by the as-obtained carbon-encapsulated mono- and bi-transition metal nanoparticles exhibit excellent electro-catalytic activity for hydrogen production in alkaline water electrolysis. Especially, Ni0.4Co0.6@N-Cs800-b catalyst prepared at 800 °C under an argon flow exhibited the best electrocatalytic performance towards HER. The high HER activity of the Ni0.4Co0.6@N-Cs800-b modified electrode is related to the appropriate nickel-cobalt metal ratio with high crystallinity, complete and homogeneous carbon layers outside of the nickel-cobalt with high conductivity and the synergistic effect of nickel-cobalt alloys that also accelerate electron transfer process.

A Janus cobalt-based catalytic material for electro-splitting of water

NASA Astrophysics Data System (ADS)

Cobo, Saioa; Heidkamp, Jonathan; Jacques, Pierre-André; Fize, Jennifer; Fourmond, Vincent; Guetaz, Laure; Jousselme, Bruno; Ivanova, Valentina; Dau, Holger; Palacin, Serge; Fontecave, Marc; Artero, Vincent

2012-09-01

The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable and efficient systems for the conversion and storage of renewable energy sources. The production of hydrogen through water splitting seems a promising and appealing solution. We found that a robust nanoparticulate electrocatalytic material, H2-CoCat, can be electrochemically prepared from cobalt salts in a phosphate buffer. This material consists of metallic cobalt coated with a cobalt-oxo/hydroxo-phosphate layer in contact with the electrolyte and mediates H2 evolution from neutral aqueous buffer at modest overpotentials. Remarkably, it can be converted on anodic equilibration into the previously described amorphous cobalt oxide film (O2-CoCat or CoPi) catalysing O2 evolution. The switch between the two catalytic forms is fully reversible and corresponds to a local interconversion between two morphologies and compositions at the surface of the electrode. After deposition, the noble-metal-free coating thus functions as a robust, bifunctional and switchable catalyst.

Ear piercing, and nickel and cobalt sensitization, in 520 young Swedish men doing compulsory military service.

PubMed

Meijer, C; Bredberg, M; Fischer, T; Widström, L

1995-03-01

Piercing the earlobes has increased in popularity among males in recent years. This habit would be expected to increase the incidence of nickel and cobalt sensitization. Patch testing with nickel sulfate and cobalt chloride was performed in 520 young Swedish men doing compulsory military service. The overall frequency of nickel/cobalt positive tests was 4.2%. The prevalence of nickel/cobalt positive tests was significantly higher (p < 0.05) in 152 men with pierced earlobes (7.9%) than in those 368 with unpierced earlobes (2.7%). A history of hand eczema (7/152 = 4.6%) or other types of eczema (22/152 = 14.5%) in individuals with pierced earlobes was no more common than in those with unpierced earlobes: 24/368 = 6.5% and 51/386 = 13.9%, respectively (n.s.). Hand eczema was no more common in sensitized (1/22 = 4.5%) than in nonsensitized individuals (32/498 = 6.4%) (n.s.).

Thermal degradation of Shredded Oil Palm Empty Fruit Bunches (SOPEFB) embedded with Cobalt catalyst by Thermogravimetric Analysis (TGA)

NASA Astrophysics Data System (ADS)

Alias, R.; Hamid, N. H.; Jaapar, J.; Musa, M.; Alwi, H.; Halim, K. H. Ku

2018-03-01

Thermal behavior and decomposition kinetics of shredded oil palm empty fruit bunches (SOPEFB) were investigated in this study by using thermogravimetric analysis (TGA). The SOPEFB were analyzed under conditions of temperature 30 °C to 900 °C with nitrogen gas flow at 50 ml/min. The SOPEFB were embedded with cobalt (II) nitrate solution with concentration 5%, 10%, 15% and 20%. The TG/DTG curves shows the degradation behavior of SOPEFB following with char production for each heating rate and each concentration of cobalt catalyst. Thermal degradation occurred in three phases, water drying phase, decomposition of hemicellulose and cellulose phase, and lignin decomposition phase. The kinetic equation with relevant parameters described the activation energy required for thermal degradation at the temperature regions of 200 °C to 350 °C. Activation energy (E) for different heating rate with SOPEFB embedded with different concentration of cobalt catalyst showing that the lowest E required was at SOPEFB with 20% concentration of cobalt catalyst..

40 CFR 471.32 - Effluent limitations representing the degree of effluent reduction attainable by the application...

Code of Federal Regulations, 2011 CFR

2011-07-01

... (pounds per million off-pounds) of nickel-cobalt rolled with emulsions Chromium 0.063 0.026 Nickel 0.094 0... nickel-cobalt rolled with water Chromium 0.028 0.011 Nickel 0.042 0.028 Fluoride 4.49 1.99 (d) Tube... monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt drawn with emulsions Chromium 0...

Use of phosphate for separation of cobalt from iron

USGS Publications Warehouse

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.

Cobalt-Base Alloy Gun Barrel Study

DTIC Science & Technology

2014-07-01

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... Gun Barrel Study 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) William S. de Rosset and Jonathan S. Montgomery

Cobalt nanoparticles on charcoal: a versatile catalyst in the Pauson-Khand reaction, hydrogenation, and the reductive Pauson-Khand reaction.

PubMed

Son, Seung Uk; Park, Kang Hyun; Chung, Young Keun

2002-10-31

[formula: see text] Dispersions of nanometer-sized cobalt particles with very high stability were prepared in charcoal and analyzed by electron microscopy and X-ray analysis. The resulting cobalt nanoparticles on charcoal (CNC) were successfully used as a catalyst for the carbonylative cycloaddition of alkyne, alkene, and carbon monoxide (Pauson-Khand reaction), hydrogenation, and the reductive Pauson-Khand reaction.

Recovery of cobalt from spent lithium-ion batteries using supercritical carbon dioxide extraction.

PubMed

Bertuol, Daniel A; Machado, Caroline M; Silva, Mariana L; Calgaro, Camila O; Dotto, Guilherme L; Tanabe, Eduardo H

2016-05-01

Continuing technological development decreases the useful lifetime of electronic equipment, resulting in the generation of waste and the need for new and more efficient recycling processes. The objective of this work is to study the effectiveness of supercritical fluids for the leaching of cobalt contained in lithium-ion batteries (LIBs). For comparative purposes, leaching tests are performed with supercritical CO2 and co-solvents, as well as under conventional conditions. In both cases, sulfuric acid and H2O2 are used as reagents. The solution obtained from the supercritical leaching is processed using electrowinning in order to recover the cobalt. The results show that at atmospheric pressure, cobalt leaching is favored by increasing the amount of H2O2 (from 0 to 8% v/v). The use of supercritical conditions enable extraction of more than 95wt% of the cobalt, with reduction of the reaction time from 60min (the time employed in leaching at atmospheric pressure) to 5min, and a reduction in the concentration of H2O2 required from 8 to 4% (v/v). Electrowinning using a leach solution achieve a current efficiency of 96% and a deposit with cobalt concentration of 99.5wt%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recovery of lithium and cobalt from spent lithium-ion batteries using organic acids: Process optimization and kinetic aspects.

PubMed

Golmohammadzadeh, Rabeeh; Rashchi, Fereshteh; Vahidi, Ehsan

2017-06-01

An environmentally-friendly route based on hydrometallurgy was investigated for the recovery of cobalt and lithium from spent lithium ion batteries (LIBs) using different organic acids (citric acid, Dl-malic acid, oxalic acid and acetic acid). In this investigation, response surface methodology (RSM) was utilized to optimize leaching parameters including solid to liquid ratio (S/L), temperature, acid concentration, type of organic acid and hydrogen peroxide concentration. Based on the results obtained from optimizing procedure, temperature was recognized as the most influential parameter. In addition, while 81% of cobalt was recovered, the maximum lithium recovery of 92% was achieved at the optimum leaching condition of 60°C, S/L: 30gL -1 , citric acid concentration: 2M, hydrogen peroxide concentration: 1.25Vol.% and leaching time: 2h. Furthermore, results displayed that ultrasonic agitation will enhance the recovery of lithium and cobalt. It was found that the kinetics of cobalt leaching is controlled by surface chemical reaction at temperatures lower than 45°C. However, diffusion through the product layer at temperatures higher than 45°C controls the rate of cobalt leaching. Rate of lithium reaction is controlled by diffusion through the product layer at all the temperatures studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anion-Regulated Selective Generation of Cobalt Sites in Carbon: Toward Superior Bifunctional Electrocatalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Gang; Yang, Ce; Zhao, Wanpeng

The introduction of active transition metal sites (TMSs) in carbon enables the synthesis of noble-metal-free electrocatalysts for clean energy conversion applications, however, there are often multiple existing forms of TMSs, which are of different natures and catalytic models. Regulating the evolution of distinctive TMSs is highly desirable but remains challenging to date. Anions, as essential elements involved in the synthesis, have been totally neglected previously in the construction of TMSs. Herein, the effects of anions on the creation of different types of TMSs is investigated for the first time. It is found that the active cobalt-nitrogen sites tend to bemore » selectively constructed on the surface of N-doped carbon by using chloride, while metallic cobalt nanoparticles encased in protective graphite layers are the dominant forms of cobalt species with nitrate ions. The obtained catalysts demonstrate cobalt-sites-dependent activity for ORR and HER in acidic media. And the remarkably enhanced catalytic activities approaching that of benchmark Pt/C in acidic medium has been obtained on the catalyst dominated with cobalt-nitrogen sites, confirmed by the advanced spectroscopic . Our finding demonstrates a general paradigm of anion-regulated evolution of distinctive TMSs, providing a new pathway for enhancing performances of various targeted reactions related with TMSs.« less

HAEM SYNTHASE AND COBALT PORPHYRIN SYNTHASE IN VARIOUS MICRO-ORGANISMS.

PubMed

PORRA, R J; ROSS, B D

1965-03-01

1. The preparation of a crude extract of Clostridium tetanomorphum containing cobalt porphyrin synthase but little haem-synthase activity is described. 2. The properties of cobalt porphyrin synthase in the clostridial extracts is compared with the properties of a haem synthase present in crude extracts of the yeast Torulopsis utilis. 3. Cobalt porphyrin synthase in extracts of C. tetanomorphum inserts Co(2+) ions into the following dicarboxylic porphyrins in descending order of rate of insertion: meso-, deutero- and proto-porphyrins. Esterification renders meso- and deutero-porphyrins inactive as substrates. Neither the tetracarboxylic (coproporphyrin III) nor the octacarboxylic (uroporphyrin III) compounds are converted into cobalt porphyrins by the extract, but the non-enzymic incorporation of Co(2+) ions into these two porphyrins is rapid. These extracts are unable to insert Mn(2+), Zn(2+), Mg(2+) or Cu(2+) ions into mesoporphyrin. 4. Crude extracts of T. utilis readily insert both Co(2+) and Fe(2+) ions into deutero-, meso, and proto-porphyrins. Unlike the extracts of C. tetanomorphum, these preparations catalyse the insertion of Co(2+) ions into deuteroporphyrin more rapidly than into mesoporphyrin. This parallels the formation of haems by the T. utilis extract. 5. Cobalt porphyrin synthase is present in the particulate fraction of the extracts of C. tetanomorphum but requires a heat-stable factor present in the soluble fraction. This soluble factor can be replaced by GSH. 6. Cobalt porphyrin synthase in the clostridial extract is inhibited by iodoacetamide and to a smaller extent by p-chloromercuribenzoate and N-ethylmaleimide. The haem synthases of T. utilis and Micrococcus denitrificans are also inhibited by various thiol reagents.

Evaluation of Occupational Exposure of Glazers of a Ceramic Industry to Cobalt Blue Dye

PubMed Central

KARGAR, Fatemeh; SHAHTAHERI, Seyed Jamaleddin; GOLBABAEI, Farideh; BARKHORDARI, Abolfazl; RAHIMI-FROUSHANI, Abbas; KHADEM, Monireh

2013-01-01

Background: Cobalt is one of the most important constituent present in ceramic industries. Glazers are the relevant workers when they are producing blue colored ceramic, causing occupational exposure to such metal. Through this study, urinary cobalt was determined in glazers in a ceramic industry when they were producing blue-colored ceramic glazes. Methods: In this case-control study, spot urine samples were collected from 49 glazers at the start and end of work shifts (totally 98 samples) in 2011. Control group were well matched for age, height, and weight. A solid phase extraction system was used for separation and preconcentration of samples followed by analysis by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). All participants filled out a self administered questionnaire comprises questions about duration of exposure, work shift, use of mask, skin dermatitis, kind of job, ventilation system, overtime work, age, weight, and height. The lung function tests were performed on each control and cobalt exposed subjects. Analysis of covariance (ANCOVA) was used to evaluate the obtained results. Results: Urinary levels of cobalt were significantly higher in the glazers compared to the control group. There were significant differences at urinary concentration of cobalt at the start and end of the work shift in glazers. Spirometric parameters were significantly lower in the glazers compared to the control group. Among the variables used in questionnaire the significant variables were dermatitis skin, mask, ventilation, and overtime work. Conclusion: This study verified existence of cobalt in the urine glazers, showing lower amount than the ACGIH standard. PMID:26056641

Deposition and properties of cobalt- and ruthenium-based ultra-thin films

NASA Astrophysics Data System (ADS)

Henderson, Lucas Benjamin

Future copper interconnect systems will require replacement of the materials that currently comprise both the liner layer(s) and the capping layer. Ruthenium has previously been considered as a material that could function as a single material liner, however its poor ability to prevent copper diffusion makes it incompatible with liner requirements. A recently described chemical vapor deposition route to amorphous ruthenium-phosphorus alloy films could correct this problem by eliminating the grain boundaries found in pure ruthenium films. Bias-temperature stressing of capacitor structures using 5 nm ruthenium-phosphorus film as a barrier to copper diffusion and analysis of the times-to-failure at accelerated temperature and field conditions implies that ruthenium-phosphorus performs acceptably as a diffusion barrier for temperatures above 165°C. The future problems associated with the copper capping layer are primarily due to the poor adhesion between copper and the current Si-based capping layers. Cobalt, which adheres well to copper, has been widely proposed to replace the Si-based materials, but its ability to prevent copper diffusion must be improved if it is to be successfully implemented in the interconnect. Using a dual-source chemistry of dicobaltoctacarbonyl and trimethylphosphine at temperatures from 250-350°C, amorphous cobalt-phosphorus can be deposited by chemical vapor deposition. The films contain elemental cobalt and phosphorus, plus some carbon impurity, which is incorporated in the film as both graphitic and carbidic (bonded to cobalt) carbon. When deposited on copper, the adhesion between the two materials remains strong despite the presence of phosphorus and carbon at the interface, but the selectivity for growth on copper compared to silicon dioxide is poor and must be improved prior to consideration for application in interconnect systems. A single molecule precursor containing both cobalt and phosphorus atoms, tetrakis(trimethylphosphine)cobalt(0), yields cobalt-phosphorus films without any co-reactant. However, the molecule does not contain sufficient amounts of amorphizing agents to fully eliminate grain boundaries, and the resulting film is nanocrystalline.

Mixed-valent dicobalt and iron-cobalt complexes with high-spin configurations and short metal-metal bonds.

PubMed

Zall, Christopher M; Clouston, Laura J; Young, Victor G; Ding, Keying; Kim, Hyun Jung; Zherebetskyy, Danylo; Chen, Yu-Sheng; Bill, Eckhard; Gagliardi, Laura; Lu, Connie C

2013-08-19

Cobalt-cobalt and iron-cobalt bonds are investigated in coordination complexes with formally mixed-valent [M2](3+) cores. The trigonal dicobalt tris(diphenylformamidinate) compound, Co2(DPhF)3, which was previously reported by Cotton, Murillo, and co-workers (Inorg. Chim. Acta 1996, 249, 9), is shown to have an energetically isolated, high-spin sextet ground-state by magnetic susceptibility and electron paramagnetic resonance (EPR) spectroscopy. A new tris(amidinato)amine ligand platform is introduced. By tethering three amidinate donors to an apical amine, this platform offers two distinct metal-binding sites. Using the phenyl-substituted variant (abbreviated as L(Ph)), the isolation of a dicobalt homobimetallic and an iron-cobalt heterobimetallic are demonstrated. The new [Co2](3+) and [FeCo](3+) cores have high-spin sextet and septet ground states, respectively. Their solid-state structures reveal short metal-metal bond distances of 2.29 Å for Co-Co and 2.18 Å for Fe-Co; the latter is the shortest distance for an iron-cobalt bond to date. To assign the positions of iron and cobalt atoms as well as to determine if Fe/Co mixing is occurring, X-ray anomalous scattering experiments were performed, spanning the Fe and Co absorption energies. These studies show only a minor amount of metal-site mixing in this complex, and that FeCoL(Ph) is more precisely described as (Fe0.94(1)Co0.06(1))(Co0.95(1)Fe0.05(1))L(Ph). The iron-cobalt heterobimetallic has been further characterized by Mössbauer spectroscopy. Its isomer shift of 0.65 mm/s and quadrupole splitting of 0.64 mm/s are comparable to the related diiron complex, Fe2(DPhF)3. On the basis of spectroscopic data and theoretical calculations, it is proposed that the formal [M2](3+) cores are fully delocalized.

Spatial Patterns of Airborne Exposures of Tungsten and Cobalt in Fallon, Nevada, From Lichens and Surface Sediments

NASA Astrophysics Data System (ADS)

Sheppard, P. R.; Speakman, R. J.; Ridenour, G.; Glascock, M. D.; Farris, C.; Witten, M. L.

2005-12-01

This paper describes spatial patterns of airborne exposures of heavy metals in Fallon, Nevada, where a cluster of childhood leukemia has been on-going since 1997. Lichen chemistry, the measurement and interpretation of element concentrations in lichens, and surface sediment chemistry were used. Lichens were collected from within as well as from well outside of Fallon. Surface sediments were collected in a gridded spatial pattern, also within and outside of Fallon. Both the lichen and the surface sediment samples were measured chemically for a large suite of metals and other elements. Lichens indicate that Fallon itself has a high dual airborne exposure of tungsten and cobalt relative to sites well away from the town. Surface sediments samples also show high peaks of tungsten and cobalt within Fallon with nothing more than background contents away from the town. The tungsten and cobalt peaks coincide spatially with one another, with the highest values located right at a "hard-metal" facility that processes these metals. This present research confirms earlier research on total suspended particulates showing that Fallon is distinct in Nevada for its high dual exposure of airborne tungsten and cobalt and that the source of these two metals can be pinpointed to the hard-metal industry that exists just north of Highway 50 and west of Highway 95. While it is still not possible to conclude that high airborne exposure of tungsten and/or cobalt causes childhood leukemia, it can now be concluded beyond reasonable doubt that Fallon is unique environmentally due to its high airborne concentrations of tungsten and cobalt. Given that Fallon's cluster of childhood leukemia is the "most convincing cluster ever reported," it stands to reason that additional biomedical research should directly test the leukogenecity of combined airborne exposures of tungsten and cobalt.

Synthesis, structure, properties and immobilization on a gold surface of the monoribbed-functionalized tris-dioximate cobalt(II) clathrochelates and an electrocatalytic hydrogen production from H+ ions.

PubMed

Voloshin, Y Z; Belov, A S; Vologzhanina, A V; Aleksandrov, G G; Dolganov, A V; Novikov, V V; Varzatskii, O A; Bubnov, Y N

2012-05-28

The cycloaddition of the mono- and dichloroglyoximes to the cobalt(II) bis-α-benzyldioximate afforded the cobalt(II) mono- and dichloroclathrochelates in moderate yields (40-60%). These complexes undergo nucleophilic substitution of their reactive chlorine atoms with aliphatic amines, alcohols and thiolate anions. In the case of ethylenediamine and 1,2-ethanedithiol, only the macrobicyclic products with α,α'-N(2)- and α,α'-S(2)-alicyclic six-numbered ribbed fragments were obtained. The cobalt(II) cage complexes with terminal mercapto groups were synthesized using aliphatic dithiols. The crystal and molecular structures of the six cobalt(II) clathrochelates were obtained by X-ray diffraction. Their CoN(6)-coordination polyhedra possess a geometry intermediate between a trigonal prism and a trigonal antiprism, and the encapsulated cobalt(II) ions are shifted from their centres due to the structural Jahn-Teller effect with the Co-N distances varying significantly (by 0.10-0.26 Å). The electrochemistry of the complexes obtained was studied by cyclic voltammetry (CV). The anodic waves correspond to the quasi-reversible Co(2+/3+) oxidations, whereas the cathodic ranges contain the quasi-reversibile waves assigned to the Co(2+/+) reductions; all the cobalt(i)-containing clathrochelate anions formed are stable in the CV time scale. The electrocatalytic properties of the cobalt complexes obtained were studied in the production of hydrogen from H(+) ions: the addition of HClO(4) resulted in the formation of the same catalytic cathodic reduction Co(2+/+) waves. The controlled-potential electrolysis with gas chromatography analysis confirmed the production of H(2) in high Faraday yields. The efficiency of this electrocatalytic process was enhanced by an immobilization of the complexes with terminal mercapto groups on a surface of the working gold electrode.

Structural and magnetic fluence dependence in cobalt titanate thin films synthesized by pulse laser deposition

NASA Astrophysics Data System (ADS)

Prisbrey, Shon Thomas

Knowledge of the fundamental structure and magnetic characteristics of dilute magnetic semiconductors (DMSs) is an essential step towards the development of spin-polarized electronics (spintronics). Recently (2001), the report of ferromagnetism in cobalt-doped anatase titania films synthesized by pulse laser deposition (PLD) elicited interest as a possible DMS oxide. Other investigations of the CoxTi1-xO2-delta material system, utilizing a myriad of deposition techniques, yielded conflicting results as to the source of magnetism and the local environment of the deposited cobalt. No complete characterization of PLD synthesized films has been reported. This dissertation quantifies the effect of laser fluence on film morphology, structure, and magnetic properties by fully characterizing CoxTi1-x O2-delta films grown under optimal PLD deposition conditions that were identified separately in prior published work. The construction of a custom PLD system that provided repeatable laser/target interaction via a combination of fluence and target movement is addressed. A brief outline of magnetism and its relation to structure is also given. The remainder of the dissertation details the effect of laser fluence on Co0.049Ti0.951O2-delta and Co 0.038Ti0.962O2-delta films. Film structure, morphology, and magnetic properties were determined for illumination conditions corresponding to laser fluences varying from 0.57 to 1.37 J/cm2. The local cobalt environment is strongly correlated with laser fluence. Cobalt in 4.9% concentration films grown with a laser fluence between 0.7 and 0.93 J/cm2 were octahedrally coordinated, as were 3.8% films grown with a fluence less than 0.93 J/cm2. Departure of the laser fluence from these ranges results in a multitude of cobalt environments in the films. The film magnetization is observed to be a function of laser fluence with a maximum moment of ˜3.19 muB per cobalt atom occurring at 0.93 J/cm2 in the 4.9% films and ˜1.9 muB per cobalt atom at 0.57 J/cm2 in the 3.8% films. There is no evidence of cobalt segregation and subsequent formation of metallic cobalt in the high moment films. A departure in laser fluence from the maximum moment conditions results in a drop in moment to ˜1 muB. An appendix detailing previous work that investigated iridium as an oxidation resistant capping layer is also included.

Synthesis and structural characterization of polyaniline/cobalt chloride composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asha, E-mail: arana5752@gmail.com; Goyal, Sneh Lata; Kishore, Nawal

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.

Evaluation of TIAX High Energy CAM-7/Graphite Lithium-Ion Batteries at High and Low Temperatures

DTIC Science & Technology

2014-08-01

phosphate ( LiFePO4 or LFP), lithium nickel cobalt manganese oxide (LiNixCoyMnzO2 or NCM), LCO, and NCA, CAM-7 based 18650 cells have a higher specific...electric vehicles HT high temperature Li lithium LiCoO2 or LCO lithium cobalt oxide LiCoPO4 or LCP lithium cobalt phosphate LiFePO4 or LFP lithium

Investigating the Catalytic Growth of Carbon Nanotubes with In Situ Raman Monitoring

DTIC Science & Technology

2015-06-01

single-walled carbon nanotube growth using cobalt deposited on Si/SiO2 as a model system. In situ Raman studies revealed that thin catalyst layers... cobalt thickness were studied. Surface analyses showed that during the catalyst preparation, catalyst atoms at the interface with silica form small...nanostructures. However, highly-reducing conditions are required to reduce the small silicate domains into small cobalt particles able to grow single-walled

The response of cobalt-free Udimet 700 type alloy to modified heat treatments

NASA Technical Reports Server (NTRS)

Harf, F. H.

1986-01-01

A superalloy based on Udimet 700, in which all of the cobalt was replaced by nickel, was prepared from hot isostatically pressed prealloyed powders. This material was given various heat treatments consisting of partial solutioning and aging in a sequence of four different temperatures. Comparisons were made of microstructures and mechanical properties. Best results were obtained by partially solutioning at 1145 deg C and aging through a sequence of 870, 1030, 650 and 760 deg C. This heat treatment also provided significantly improved properties for wrought material of the same composition. The results suggest that cobalt free Udimet 700 should be considered as a substitute for Udimet 700 with the standard 17 percent cobalt content.

The response of cobalt-free Udimet 700 type alloy to modified heat treatments

NASA Technical Reports Server (NTRS)

Harf, F. H.

1985-01-01

A superalloy based on Udimet 700, in which all of the cobalt was replaced by nickel, was prepared from hot isostatically pressed prealloyed powders. This material was given various heat treatments consisting of partial solutioning and aging in a sequence of four different temperatures. Comparisons were made of microstructures and mechanical properties. Best results were obtained by partially solutioning at 1145 deg C and aging through a sequence of 870, 1030, 650 and 760 deg C. This heat treatment also provided significantly improved properties for wrought material of the same composition. The results suggest that cobalt free Udimet 700 should be considered as a substitute for Udimet 700 with the standard 17 percent cobalt content.

Survey of Portions of the Chromium-Cobalt-Nickel-Molybdenum Quaternary System at 1,200 Degrees C

NASA Technical Reports Server (NTRS)

Rideout, Sheldon Paul; Beck, Paul A

1953-01-01

A survey was made of portions of the chromium-cobalt-nickel-molybdenum quaternary system at 1,200 degrees c by means of microscopic and x-ray diffraction studies. Since the face-centered cubic (alpha) solid solutions form the matrix of almost all practically useful high-temperature alloys, the solid solubility limits of the quaternary alpha phase were determined up to 20 percent molybdenum. The component cobalt-nickel-molybdenum, chromium-cobalt-molybdenum, and chromium-nickel-molybdenum ternary systems were also studied. The survey of these systems was confined to the determination of the boundaries of the face-centered cubic (alpha) solid solutions and of the phases coexisting with alpha at 1,200 degrees c.

Metal-metal bond lengths in complexes of transition metals.

PubMed

Pauling, L

1976-12-01

In complexes of the transition metals containing clusters of metal atoms the cobalt-cobalt bond lengths are almost always within 1 pm of the single-bond value 246 pm given by the enneacovalent radius of cobalt, whereas most of the observed iron-iron bond lengths are significantly larger than the single-bond value 248 pm, the mean being 264 pm, which corresponds to a half-bond. A simple discussion of the structures of these complexes based on spd hybrid orbitals, the electroneutrality principle, and the partial ionic character of bonds between unlike atoms leads to the conclusion that resonance between single bonds and no-bonds would occur for iron and its congeners but not for cobalt and its congeners, explaining the difference in the bond lengths.

Variation in band gap energy and electrical analysis of double doped cobalt ferrite

NASA Astrophysics Data System (ADS)

Parveen, Azra; Agrawal, Shraddha; Azam, Ameer

2018-05-01

The Ca and Cr doped cobalt ferrite nanoparticles (Co0.9Ca0.1) (Fe0.8 Cr0.2)2O4 were synthesized by microwave gel combustion method. Microstructural studies were carried out by XRD and SEM. Structural studies suggest that the crystal system remains spinal even with the doping of calcium and chromium. The SEM image shows the spherical morphology of surface of the sample. Optical properties of Ca and Cr doped cobalt ferrite were studied by UV-visible technique in the range of 400-600 nm. The electrical conductivity of pure and doped cobalt ferrite were studied as a function of frequency and were explained on the basis of electron hopping.

Ultrafast intersystem crossings in Fe-Co Prussian blue analogues

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Veenendaal, Michel

Ultrafast spincrossover is studied in Fe-Co Prussian blue analogues using a dissipative quantum-mechanical model of a cobalt ion coupled to a breathing mode. All electronic interactions are treated on an equal footing. It is theoretically demonstrated that the divalent cobalt ion reaches 90% of the S = 3/2 value within 20 fs after photoexciting a low-spin Co 3+ ion by an iron-to-cobalt charge transfer. The doublet-to-quartet spin crossover is significantly faster than the oscillation period of the breathing mode. The system relaxes to the lowest manifold of divalent cobalt ( 4T 1) in 150-200 fs. In conclusion, strong oscillations inmore » spin-orbit coupling and the involvement of higher-lying quartets are found.« less

Ultrafast intersystem crossings in Fe-Co Prussian blue analogues

DOE PAGES

van Veenendaal, Michel

2017-07-27

Ultrafast spincrossover is studied in Fe-Co Prussian blue analogues using a dissipative quantum-mechanical model of a cobalt ion coupled to a breathing mode. All electronic interactions are treated on an equal footing. It is theoretically demonstrated that the divalent cobalt ion reaches 90% of the S = 3/2 value within 20 fs after photoexciting a low-spin Co 3+ ion by an iron-to-cobalt charge transfer. The doublet-to-quartet spin crossover is significantly faster than the oscillation period of the breathing mode. The system relaxes to the lowest manifold of divalent cobalt ( 4T 1) in 150-200 fs. In conclusion, strong oscillations inmore » spin-orbit coupling and the involvement of higher-lying quartets are found.« less

Effect of Cobalt Particle Size on Acetone Steam Reforming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Junming; Zhang, He; Yu, Ning

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,more » and the oxidation state of the cobalt nanoparticles.« less

Study of the influence of the bridge on the magnetic coupling in cobalt(II) complexes.

PubMed

Fabelo, Oscar; Cañadillas-Delgado, Laura; Pasán, Jorge; Delgado, Fernando S; Lloret, Francesc; Cano, Joan; Julve, Miguel; Ruiz-Pérez, Catalina

2009-12-07

Two new cobalt(II) complexes of formula [Co(2)(bta)(H(2)O)(6)](n) x 2nH(2)O (1) and [Co(phda)(H(2)O)](n) x nH(2)O (2) [H(4)bta = 1,2,4,5-benzenetetracarboxylic acid, H(2)phda = 1,4-phenylenediacetic acid] have been characterized by single crystal X-ray diffraction. Compound 1 is a one-dimensional compound where the bta(4-) ligand acts as 2-fold connector between the cobalt(II) ions through two carboxylate groups in para-conformation. Triply bridged dicobalt(II) units occur within each chain, a water molecule, a carboxylate group in the syn-syn conformation, and an oxo-carboxylate with the mu(2)O(1);kappa(2)O(1),O(2) coordination mode acting as bridges. Compound 2 is a three-dimensional compound, where the phda(2-) group acts as a bridge through its two carboxylate groups, one of them adopting the mu-O,O' coordination mode in the syn-syn conformation and the other exhibiting the single mu(2)-O'' bridging mode. As in 1, chains of cobalt(II) ions occur in 2 with a water molecule, a syn-syn carboxylate group, and an oxo-carboxylate constitute the triply intrachain bridging skeleton. Each chain is linked to other four ones through the phda(2-) ligand, giving rise to the three-dimensional structure. The values of the intrachain cobalt-cobalt separation are 3.1691(4) (1) and 3.11499(2) A (2) whereas those across the phenyl ring of the extended bta(4-) (1) and phda(2-) (2) groups are 10.1120(6) and 11.4805(69 A, respectively. The magnetic properties of 1 and 2 have been investigated in the temperature range 1.9-300 K, and their analysis has revealed the occurrence of moderate intrachain ferromagnetic couplings [J = +5.4 (1) and +2.16 cm(-1) (2), J being the isotropic magnetic coupling parameter], the magnetic coupling through the extended bta(4-) and phda(2-) with cobalt-cobalt separations larger than 10 A being negligible. The nature and magnitude of the magnetic interactions between the high-spin cobalt(II) ions in 1 and 2 are compared to those of related systems and discussed as a function of the complementarity-countercomplementarity effects of the triple bridges.

Tribocorrosion: Ceramic and Oxidized Zirconium vs Cobalt-Chromium Heads in Total Hip Arthroplasty.

PubMed

Tan, Sok Chuen; Lau, Adrian C K; Del Balso, Christopher; Howard, James L; Lanting, Brent A; Teeter, Matthew G

2016-09-01

This matched-cohort study aims to compare tribocorrosion between matched ceramic and cobalt-chromium femoral head trunnions and between matched Oxinium and cobalt-chromium femoral head trunnions. Secondary objectives were to investigate whether taper design, depth of trunnion, implantation time, age, body mass index, and gender have an effect on fretting and corrosion. All hip prostheses retrieved between 1999 and 2015 at one center were reviewed, giving a total of 52 ceramic heads. These were matched to a cobalt-chromium cohort according to taper design, head size, neck length, and implantation time. The trunnions were examined by 2 observers using a 4-point scoring technique and scored in 3 zones: apex, middle, and base. The observers were blinded to clinical and manufacturing data where possible. A separate matched-cohort analysis was performed between 8 Oxinium heads and 8 cobalt-chromium heads, which were similarly scored. Ceramic head trunnions demonstrated a lower median fretting and corrosion score at the base zone (P < .001), middle zone (P < .001), and in the combined score (P < .001). Taper design had a significant effect on fretting and corrosion in the apex zone (P = .04) of the ceramic group, as well as the cobalt-chromium group (P = .03). Between Oxinium heads and cobalt-chromium heads, there was no significant difference in the fretting and corrosion score across all 3 zones (base: P = .22; middle: P = .92; and apex: P = .71) and for the combined score (P = .67). This study shows that ceramic head confers an advantage in trunnion fretting and corrosion. Taper design and implantation time were also significant factors for fretting and corrosion. Copyright © 2016 Elsevier Inc. All rights reserved.

Age-related impairments of mobility associated with cobalt and other heavy metals: Data from NHANES 1999-2004

PubMed Central

Lang, Iain A; Scarlett, Alan; Guralnik, Jack; Depledge, Michael H; Melzer, David; Galloway, Tamara S

2012-01-01

Introduction Exposure to heavy metals can promote oxidative stress and damage to cellular components, and may accelerate age-related disease and disability.. Physical mobility is a validated biomarker of age-related disability and is predictive of hospitalization and mortality. Aim To examine associations between selected heavy metals and impaired lower limb mobility in a representative older human population. Methods Data for 1615 adults aged ≥60 years from the National Health and Nutrition Examination Survey (NHANES) 1999 to 2004 were used to identify associations between urinary concentrations of 10 metals with self-reported and measured walking impairments (at p<0.01). Models were adjusted for confounding factors, including smoking. Results In models adjusted for age, sex and ethnicity, elevated levels of cadmium, cobalt and uranium were associated with impairment of the ability to walk a quarter mile. In fully adjusted models, cobalt was the only metal that remained associated: the odds ratio for reporting walking problems with a 1-unit increase in logged cobalt concentration (μg L-1) was 1.43 (95% CI 1.12 to 1.84). Cobalt was also the only metal associated with an increased measured time to walk a 20 foot course (p=0.008). In analyses of disease categories to explain the mobility finding, cobalt was associated with physician diagnosed arthritis (1-unit increase OR=1.22 (95% CI 1.00 to 1.49, p=0.045). Conclusions Low level cobalt exposure, assessed through urinary concentrations of this essential heavy metal may be a risk factor for age-related physical impairments. Independent replication is needed to confirm this association. PMID:19199147

Caprine hepatic lipidosis induced through the intake of low levels of dietary cobalt.

PubMed

Johnson, Eugene H; Al-Habsi, Khalid; Kaplan, Evelyn; Srikandakumar, Anandarajah; Kadim, Isam T; Annamalai, Kanthi; Al-Busaidy, Rashid; Mahgoub, Osman

2004-09-01

Forty-one, 10-week-old newly weaned goats were randomly allocated into two groups, namely control (n=22) and treated (n=19). Kids in both groups were fed Rhodegrass hay ad libitum that contained < 0.1 mg/kg DM cobalt and 150 g/day of a commercially prepared ruminant concentrate that contained approximately 0.12 mg/kg DM cobalt. This diet provided the minimum daily requirement of cobalt as specified for sheep. The treated goats were supplemented with bi-monthly subcutaneous injections of 2000 microg of hydroxycobalamin. All goats were weighed and blood samples collected monthly for haematological, clinical biochemical and serum vitamin B12 analysis. After a 10-month experimental period the goats were slaughtered. The control animals exhibited significantly (P<0.05) lower weight gains, and had dry scruffy hair coats. In addition, there was a decline in erythrocyte counts, mean haemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. Controls also exhibited significantly (P<0.05) lower levels of total serum proteins and elevated levels of serum alkaline phosphatase compared to treated goats. Fourteen (63.6%) of the control goats developed pathology consistent with reported field cases of hepatic lipidosis associated with low liver levels of cobalt. Only one (5.3%) of the treated goats developed hepatic lipidosis. Contrary to previous reports that suggested that goats are less sensitive to low levels of dietary cobalt than sheep, it is apparent that this is not the case with Omani goats. This is the first report of the induction of hepatic lipidosis in goats due to feeding low levels of cobalt in their diet.

Controlling ZIF-67 crystals formation through various cobalt sources in aqueous solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Xiangli; Jiangsu Key Laboratory of Advanced Metallic Materials, Nanjing 211189; Xing, Tiantian

2016-03-15

Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120 °C) and non-hydrothermal (room temperature) from various cobalt sources and 2-methylimidazolate (Hmim) in aqueous solution within 30 min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co{sup 2+} molar ratios and experimental condition. Using Co(NO{sub 3}){sub 2} as cobalt source, small-sized ZIF-67 crystals with agglomeration were formed. For CoCl{sub 2}, small-sized rhombic dodecahedron were obtained. While large-sized crystals of rhombic dodecahedron structure were obtained from CoSO{sub 4} and Co(OAc){sub 2}. Under hydrothermal condition, the size of ZIF-67 crystals tended to be moremore » uniform and the morphology were more regular comparing to non-hydrothermal condition. This study provides a simple way to control the size and morphology of ZIF-67 crystals prepared in aqueous solution. - Graphical abstract: Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120 °C) and non-hydrothermal (room temperature) from four different cobalt sources (Co(NO{sub 3}){sub 2}, CoCl{sub 2}, CoSO{sub 4} and Co(OAc){sub 2}) in aqueous solution within 30 min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co{sup 2+} molar ratios and experimental condition. - Highlights: • The particle size and morphology were determined by the reactivity of cobalt salt. • ZIF-67 could be prepared from CoSO{sub 4} and Co(OAc){sub 2} at Hmim/Co{sup 2+} molar ratio of 10. • Uniform and regular particles were obtained under hydrothermal condition.« less

Microwave combustion synthesis of Co1-xZnxFe2O4 (0⩽x⩽0.5): Structural, magnetic, optical and vibrational spectroscopic studies.

PubMed

Sundararajan, M; Kennedy, L John; Vijaya, J Judith; Aruldoss, Udaya

2015-04-05

Nanostructured pure and zinc doped cobalt ferrites (Co1-xZnxFe2O4 where x fraction ranging from 0 to 0.5) were prepared by microwave combustion method employing urea as a fuel. The nanostructured samples were characterized by using various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy, energy dispersive X-ray analysis, UV-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy and Fourier transformed infrared (FT-IR) spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis and the FT-IR spectroscopy revealed the formation of cobalt ferrite cubic spinel-type structure. The average crystallite sizes for the samples were in the range of 3.07-11.30 nm. The direct band gap (Eg) was estimated using Kubelka-Munk method and is obtained from the UV-vis spectra. The band gap value decreased with an increase in zinc fraction (2.56-2.17 eV). The violet and green emission observed in the photoluminescence spectra revealed that cobalt ferrites are governed by defect controlled processes. The elemental analysis of zinc doped cobalt ferrites were obtained from energy dispersive X-ray (EDX) analysis. From the magnetic measurements, it is observed that cobalt ferrite and zinc doped cobalt ferrite systems fall under the soft ferrite category. The saturation magnetization (Ms) value of undoped cobalt ferrite is 14.26 emu/g, and it has reached a maximum of 29.61 emu/g for Co0.7Zn0.3Fe2O4. Copyright © 2014 Elsevier B.V. All rights reserved.

Controlled cobalt doping in the spinel structure of magnetosome magnetite: new evidences from element- and site-specific X-ray magnetic circular dichroism analyses

PubMed Central

Menguy, Nicolas; Arrio, Marie-Anne; Sainctavit, Philippe; Juhin, Amélie; Wang, Yinzhao; Chen, Haitao; Bunau, Oana; Otero, Edwige; Ohresser, Philippe; Pan, Yongxin

2016-01-01

The biomineralization of magnetite nanocrystals (called magnetosomes) by magnetotactic bacteria (MTB) has attracted intense interest in biology, geology and materials science due to the precise morphology of the particles, the chain-like assembly and their unique magnetic properties. Great efforts have been recently made in producing transition metal-doped magnetosomes with modified magnetic properties for a range of applications. Despite some successful outcomes, the coordination chemistry and magnetism of such metal-doped magnetosomes still remain largely unknown. Here, we present new evidences from X-ray magnetic circular dichroism (XMCD) for element- and site-specific magnetic analyses that cobalt is incorporated in the spinel structure of the magnetosomes within Magnetospirillum magneticum AMB-1 through the replacement of Fe2+ ions by Co2+ ions in octahedral (Oh) sites of magnetite. Both XMCD at Fe and Co L2,3 edges, and energy-dispersive X-ray spectroscopy on transmission electron microscopy analyses reveal a heterogeneous distribution of cobalt occurring either in different particles or inside individual particles. Compared with non-doped one, cobalt-doped magnetosome sample has lower Verwey transition temperature and larger magnetic coercivity, related to the amount of doped cobalt. This study also demonstrates that the addition of trace cobalt in the growth medium can significantly improve both the cell growth and the magnetosome formation within M. magneticum AMB-1. Together with the cobalt occupancy within the spinel structure of magnetosomes, this study indicates that MTB may provide a promising biomimetic system for producing chains of metal-doped single-domain magnetite with an appropriate tuning of the magnetic properties for technological and biomedical applications. PMID:27512138

Controlled cobalt doping in the spinel structure of magnetosome magnetite: new evidences from element- and site-specific X-ray magnetic circular dichroism analyses.

PubMed

Li, Jinhua; Menguy, Nicolas; Arrio, Marie-Anne; Sainctavit, Philippe; Juhin, Amélie; Wang, Yinzhao; Chen, Haitao; Bunau, Oana; Otero, Edwige; Ohresser, Philippe; Pan, Yongxin

2016-08-01

The biomineralization of magnetite nanocrystals (called magnetosomes) by magnetotactic bacteria (MTB) has attracted intense interest in biology, geology and materials science due to the precise morphology of the particles, the chain-like assembly and their unique magnetic properties. Great efforts have been recently made in producing transition metal-doped magnetosomes with modified magnetic properties for a range of applications. Despite some successful outcomes, the coordination chemistry and magnetism of such metal-doped magnetosomes still remain largely unknown. Here, we present new evidences from X-ray magnetic circular dichroism (XMCD) for element- and site-specific magnetic analyses that cobalt is incorporated in the spinel structure of the magnetosomes within Magnetospirillum magneticum AMB-1 through the replacement of Fe(2+) ions by Co(2+) ions in octahedral (Oh) sites of magnetite. Both XMCD at Fe and Co L2,3 edges, and energy-dispersive X-ray spectroscopy on transmission electron microscopy analyses reveal a heterogeneous distribution of cobalt occurring either in different particles or inside individual particles. Compared with non-doped one, cobalt-doped magnetosome sample has lower Verwey transition temperature and larger magnetic coercivity, related to the amount of doped cobalt. This study also demonstrates that the addition of trace cobalt in the growth medium can significantly improve both the cell growth and the magnetosome formation within M. magneticum AMB-1. Together with the cobalt occupancy within the spinel structure of magnetosomes, this study indicates that MTB may provide a promising biomimetic system for producing chains of metal-doped single-domain magnetite with an appropriate tuning of the magnetic properties for technological and biomedical applications. © 2016 The Author(s).

Experimental Determination of the Low-Energy Spectral Component of Cobalt-60 Sources

DTIC Science & Technology

1986-04-01

dependence of the TLD detectors and the dose enhancement due to the lack of electronic equilibrium have been included in the figure. A series of...energy spectrum of cobalt,60 ir- radiators is essential to the proper interpretation of dosimetry and device test data in radiation response testing...of electronic devices and circuits. It is shown that the relative magnitude of the low-energy spec- tral component of cobalt󈨀 gamma radiation can be

Composites based on SiO2 micrograins and cobalt-containing nanoparticles: Synthesis, structure, and magnetic properties

NASA Astrophysics Data System (ADS)

Yurkov, G. Yu.; Kozinkin, A. V.; Koksharov, Yu. A.; Ovchenkov, E. A.; Volkov, A. N.; Kozinkin, Yu. A.; Vlasenko, V. G.; Popkov, O. V.; Ivicheva, S. N.; Kargin, Yu. F.

2013-05-01

Cobalt-containing particles are synthesized on the surface of silicon dioxide micrograins prepared by the Stöber-Fink method. The composition and structure of nanoparticles are determined by transmission electron microscopy, X-ray diffraction analysis, and EXAFS. The average size of cobalt nanoparticles in the samples is found to be 14 ± 5 nm. The resulting composites are shown to be ferromagnetics with low specific magnetization values.

Epitaxial Growth and Electronic Structure of Half Heuslers Co1-xNixTiSb (001), Ni1-xCoxTiSn, and PtLuSb

DTIC Science & Technology

2016-01-09

studied in detail using scanning tunneling microscopy and angle resolved photoemission. For the doping levels achieved in cobalt titanium antimony, the...angle resolved photoemission. For the doping levels achieved in cobalt titanium antimony, the electron mobility at room temperature was comparable...scanning tunneling microscopy and angle resolved photoemission. For the doping levels achieved in cobalt titanium antimony, the electron mobility at room

Boron-capped tris(glyoximato) cobalt clathrochelate as a precursor for the electrodeposition of nanoparticles catalyzing H2 evolution in water.

PubMed

Anxolabéhère-Mallart, Elodie; Costentin, Cyrille; Fournier, Maxime; Nowak, Sophie; Robert, Marc; Savéant, Jean-Michel

2012-04-11

Electrochemical investigation of a boron-capped tris(glyoximato)cobalt clathrochelate complex in the presence of acid reveals that the catalytic activity toward hydrogen evolution results from an electrodeposition of cobalt-containing nanoparticles on the electrode surface at a modest cathodic potential. The deposited particles act as remarkably active catalysts for H(2) production in water at pH 7. © 2012 American Chemical Society

Ultrathin Cobalt Oxide Overlayer Promotes Catalytic Activity of Cobalt Nitride for the Oxygen Reduction Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abroshan, Hadi; Bothra, Pallavi; Back, Seoin

Here, the oxygen reduction reaction (ORR) plays a crucial role in various energy devices such as proton-exchange membrane fuel cells (PEMFCs) and metal–air batteries. Owing to the scarcity of the current state-of-the-art Pt-based catalysts, cost-effective Pt-free materials such as transition metal nitrides and their derivatives have gained overwhelming interest as alternatives. In particular, cobalt nitride (CoN) has demonstrated a reasonably high ORR activity. However, the nature of its active phase still remains elusive. Here, we employ density functional theory calculations to study the surface reactivity of rocksalt (RS) and zincblend (ZB) cobalt nitride. The performances of the catalysts terminated bymore » the facets of (100), (110), and (111) are studied for the ORR. We demonstrate that the cobalt nitride surface is highly susceptible to oxidation under ORR conditions. The as-formed oxide overlayer on the facets of CoN RS(100) and CoN ZB(110) presents a significant promotional effect in reducing the ORR overpotential, thereby increasing the activity in comparison with those of the pure CoNs. The results of this work rationalize a number of experimental reports in the literature and disclose the nature of the active phase of cobalt nitrides for the ORR. Moreover, they offer guidelines for understanding the activity of other transition metal nitrides and designing efficient catalysts for future generation of PEMFCs.« less

Contact dermatitis to cobalt chloride with an unusual mechanism.

PubMed

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

2015-10-01

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

Cobalt supplementation promotes hypoxic tolerance and facilitates acclimatization to hypobaric hypoxia in rat brain.

PubMed

Shrivastava, Kalpana; Ram, M Sai; Bansal, Anju; Singh, S S; Ilavazhagan, G

2008-01-01

In the present study, we report the molecular mechanisms of action by cobalt in facilitating acclimatization to hypobaric hypoxia using male Sprague-Dawley rats as the model system. We determined hypoxic gasping time and survival time as a measure to assess the degree of tolerance of animals to hypobaric hypoxia by exposing the animals to an altitude of 10,668 m. Oral administration of cobalt chloride (12.5 mg Co/kg body weight, BW, for 7 days) increased gasping time and hypoxic survival time by 3 to 4 times compared to the control animals. This could be attributed to an increased expression and the DNA binding activity of hypoxia inducible transcriptional factor (HIF-1alpha) and its regulated genes, that is, erythropoietin (EPO), vascular endothelial growth factor (VEGF), glucose transporter-1 (Glut-1), and nitric oxide synthase (NOS) levels. This in turn leads to better oxygenation, oxygen delivery, glucose transport, and maintenance of vascular tone, respectively, under oxygen-limited conditions. This was further confirmed by lower levels of lactate dehydrogenase (LDH) activity and lactate in the brain of cobalt + hypoxia group compared with animals exposed to hypoxia. Glucose levels also increased after cobalt supplementation. The findings of the study provide a basis for the possible use of cobalt for facilitating acclimatization to hypoxia and other conditions involving oxygen deprivation.

Surfactant-cobalt(III) complexes: The impact of hydrophobicity on interaction with HSA and DNA - insights from experimental and theoretical approach.

PubMed

Veeralakshmi, Selvakumar; Sabapathi, Gopal; Nehru, Selvan; Venuvanalingam, Ponnambalam; Arunachalam, Sankaralingam

2017-05-01

To develop surfactant-based metallodrugs, it is very important to know about their hydrophobicity, micelle forming capacity, their interaction with biomacromolecules such as proteins and nucleic acids, and biological activities. Here, diethylenetriamine (dien) and tetradecylamine ligand (TA) based surfactant-cobalt(III) complexes with single chain domain, [Co(dien)(TA)Cl 2 ]ClO 4 (1) and double chain domain [Co(dien)(TA) 2 Cl](ClO 4 ) 2 (2) were chosen to study the effect of hydrophobicity on the interaction with human serum albumin and calf thymus DNA. The obtained results showed that (i) single chain surfactant-cobalt(III) complex (1) interact with HSA and DNA via electrostatic interaction and groove binding, respectively; (ii) double chain surfactant-cobalt(III) complex (2) interact with HSA and DNA via hydrophobic interaction and partial intercalation, respectively, due to the play of hydrophobicity by single and double chain domains. Further it is noted that, double chain surfactant-cobalt(III) complex interact strongly with HSA and DNA, compared single chain surfactant-cobalt(III) complex due to their more hydrophobicity nature. DFT and molecular docking studies offer insights into the mechanism and mode of binding towards the molecular target CT-DNA and HSA. Hence, the present findings will create new avenue towards the use of hydrophobic metallodrugs for various therapeutic applications. Copyright © 2017 Elsevier B.V. All rights reserved.

The crystal structures of iron and cobalt pyridine (py)–sulfates, [Fe(SO4)(py)4]n and [Co3(SO4)3(py)11]n

PubMed Central

Pham, Duyen N. K.; Roy, Mrittika; Kreider-Mueller, Ava; Golen, James A.; Manke, David R.

2018-01-01

The solid-state structures of two metal–pyridine–sulfate compounds, namely catena-poly[[tetra­kis­(pyridine-κN)iron(II)]-μ-sulfato-κ2 O:O′], [Fe(SO4)(C5H5N)4]n, (1), and catena-poly[[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ2 O:O′-[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ3 O,O′:O′′-[tris­(pyridine-κN)cobalt(II)]-μ-sulfato-κ2 O:O′], [Co3(SO4)3(C5H5N)11]n, (2), are reported. The iron compound (1) displays a polymeric structure, with infinite chains of FeII atoms adopting octa­hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ligands. The cobalt compound (2) displays a polymeric structure, with infinite chains of CoII atoms. Two of the three Co centers have an octa­hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The third Co center has an octa­hedral N3O3 coordination environment that involves three pyridine ligands, and two bridging sulfate ligands with one sulfate chelating the cobalt atom.

Geologic report and recommendations for the cobalt mission to Morocco sponsored by The Trade and Development Program of the International Development Cooperation Agency

USGS Publications Warehouse

Foose, M.P.; Rossman, D.L.

1982-01-01

A mission sponsored by the Trade and Development Program (TDP) of the International Development Cooperation Agency (IDCA) went to Morocco to evaluate the possibility of finding additional sources of cobalt in that country, as well as other types of mineralization. Information obtained during this trip shows Morocco to be a country for which much geologic information is available and in which there are many favorable target areas for future exploration. Work in the Bou Azzer district (Morocco's principal cobalt district) shows that much excellent geologic work has been done in searching for additional deposits. However, a number of useful approaches to locate cobalt have not been tried, and their use might be successful. The potential for undiscovered deposits in the Bou Azzer region seems very high. The cobalt mineralization in the Siroua uplift is different from that in the Bou Azzer district. However, geologic similarities between the two areas suggest that a genetic link may exist between the two types of mineralization. This further indicates that cobalt deposits of the Bou Azzer types might be present in the Siroua region. Examination of the Bleida copper mine shows it to be a well-exposed volcanic hosted stratabound copper deposit. Large unexplored areas containing similar rocks occur near this deposit and may contain as yet undiscovered copper mineralization.

Allergy risks with laptop computers - nickel and cobalt release.

PubMed

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

2016-06-01

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

Economics of food irradiation: Comparison between electron accelerators and cobalt-60

NASA Astrophysics Data System (ADS)

Morrison, R. M.

The Codex Alimentarius Commission's proposed international standard permits three types of ionizing radiation to be used on foods: gamma rays from radioactive cobalt-60 or cesium-137, high energy electrons, and x-rays. The latter two types of radiation are produced by electron accelerators powered by electricity. Unlike gamma rays and x-rays which can penetrate pallet loads of foods, electrons of the allowed energy levels only penetrate 1 to 3 inches when irradiated from one side. Thus, electrons are limited to treating the surface of foods or foods in thin packages or a shallow stream of grains, powders, or liquids. Average costs per kilogram (kg) of irradiating selected foods are similar for the electron accelerator and cobalt-60 irradiators analyzed in this study, but initial investment costs generally vary by U.S. $1 million. Irradiation treatment costs range from 1 to 15 U.S. cents per kg for the foods and annual volumes examined with larger volumes having lower treatment costs. Cobalt-60 is less expensive than electrons when annual volumes are below 23 million kgs. For radiation source requirements above the equivalent of about 1 million curies of cobalt-60, electrons become more economical. The largest differences in costs occur with the papaya irradiators where using x-rays to penetrate the fruit is more expensive than using cobalt-60.

Ultrathin Cobalt Oxide Overlayer Promotes Catalytic Activity of Cobalt Nitride for the Oxygen Reduction Reaction

DOE PAGES

Abroshan, Hadi; Bothra, Pallavi; Back, Seoin; ...

2018-02-12

Here, the oxygen reduction reaction (ORR) plays a crucial role in various energy devices such as proton-exchange membrane fuel cells (PEMFCs) and metal–air batteries. Owing to the scarcity of the current state-of-the-art Pt-based catalysts, cost-effective Pt-free materials such as transition metal nitrides and their derivatives have gained overwhelming interest as alternatives. In particular, cobalt nitride (CoN) has demonstrated a reasonably high ORR activity. However, the nature of its active phase still remains elusive. Here, we employ density functional theory calculations to study the surface reactivity of rocksalt (RS) and zincblend (ZB) cobalt nitride. The performances of the catalysts terminated bymore » the facets of (100), (110), and (111) are studied for the ORR. We demonstrate that the cobalt nitride surface is highly susceptible to oxidation under ORR conditions. The as-formed oxide overlayer on the facets of CoN RS(100) and CoN ZB(110) presents a significant promotional effect in reducing the ORR overpotential, thereby increasing the activity in comparison with those of the pure CoNs. The results of this work rationalize a number of experimental reports in the literature and disclose the nature of the active phase of cobalt nitrides for the ORR. Moreover, they offer guidelines for understanding the activity of other transition metal nitrides and designing efficient catalysts for future generation of PEMFCs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Twelve catalyst test runs were made; ten of these runs used catalysts that contained cobalt as the metal component, while the remaining two runs used catalysts that contained iron as the metal component. Five of the ten cobalt catalyst test runs were made with the catalysts containing one of two different shape selective components (UCC-101 and UCC-108) at two different metal component: shape selective component ratios (1:1 and 3:14). The remaining five cobalt catalyst test runs were made with the catalysts containing different additives incorporated into the cobalt. The five cobalt catalyst test runs using catalysts with different additives showedmore » that these additives had pronounced effects on the catalysts' activity, selectivity, and stability. The most outstanding effect was realized with the additive used in the Run 9 catalyst. This additive greatly improved the stability of the catalyst. While having the same initial activity of an additive-free catalyst, its deactivation rate was only one fourth of that of the additive-free catalyst. Futhermore, this additive improved the quality of the hydrocarbon product, which had a high, stable yield of olefins, and, unlike the product of any other cobalt/UCC-101 catalyst, was free of suspended wax. This lack of suspended wax resulted in jet fuel and diesel oil fractions that had substantially lower pour points than did the fractions produced from an additive-free catalyst.« less

Occupational exposure to metallic cobalt in the Province of Bergamo. Results of a 1991 survey.

PubMed

Mosconi, G; Bacis, M; Leghissa, P; Maccarana, G; Arsuffi, E; Imbrogno, P; Airoldi, L; Caironi, M; Ravasio, G; Parigi, P C

1994-06-30

The results of a survey on workers potentially exposed to cobalt in the Bergamo Province are reported. Its aim is to assess the number of workers at risk of developing respiratory disease due to the inhalation of metallic cobalt. Interest was shown after an examination of 11 cases of 'hard metal disease', which we diagnosed, in workers who came from different production areas and had different degrees of exposure. A first group of 45 factories with potential cobalt exposure was identified by consulting the archives of the Local Sanitary Units (USSL) and of the Chamber of Commerce, and by use of the telephone directory and requesting information from the producers and users of Widia tools. A second group of 2039 factories was selected from those industrial activities where we had previously ascertained the presence of grinding operations using hard metal tools with diamond wheels. This study is related to all the factories in the first group and 10% of the factories in the second group. More than 304 inspections were carried out. In this context 403 exposed workers were identified. Workplace air measurements (250 samples) and biological monitoring (> 600 samples) to determine the exposure levels to cobalt were performed. The results show an unexpected diffuse occupational exposure in different production areas where the airborne cobalt is frequently underestimated and higher than the TLV.

Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

NASA Astrophysics Data System (ADS)

Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

2016-06-01

Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

Cobalt-Catalyzed C(sp(2))-H Borylation: Mechanistic Insights Inspire Catalyst Design.

PubMed

Obligacion, Jennifer V; Semproni, Scott P; Pappas, Iraklis; Chirik, Paul J

2016-08-24

A comprehensive study into the mechanism of bis(phosphino)pyridine (PNP) cobalt-catalyzed C-H borylation of 2,6-lutidine using B2Pin2 (Pin = pinacolate) has been conducted. The experimentally observed rate law, deuterium kinetic isotope effects, and identification of the catalyst resting state support turnover limiting C-H activation from a fully characterized cobalt(I) boryl intermediate. Monitoring the catalytic reaction as a function of time revealed that borylation of the 4-position of the pincer in the cobalt catalyst was faster than arene borylation. Cyclic voltammetry established the electron withdrawing influence of 4-BPin, which slows the rate of C-H oxidative addition and hence overall catalytic turnover. This mechanistic insight inspired the next generation of 4-substituted PNP cobalt catalysts with electron donating and sterically blocking methyl and pyrrolidinyl substituents that exhibited increased activity for the C-H borylation of unactivated arenes. The rationally designed catalysts promote effective turnover with stoichiometric quantities of arene substrate and B2Pin2. Kinetic studies on the improved catalyst, 4-(H)2BPin, established a change in turnover limiting step from C-H oxidative addition to C-B reductive elimination. The iridium congener of the optimized cobalt catalyst, 6-(H)2BPin, was prepared and crystallographically characterized and proved inactive for C-H borylation, a result of the high kinetic barrier for reductive elimination from octahedral Ir(III) complexes.

Ecotoxicological assessment of cobalt using Hydra model: ROS, oxidative stress, DNA damage, cell cycle arrest, and apoptosis as mechanisms of toxicity.

PubMed

Zeeshan, Mohammed; Murugadas, Anbazhagan; Ghaskadbi, Surendra; Ramaswamy, Babu Rajendran; Akbarsha, Mohammad Abdulkader

2017-05-01

The mechanisms underlying cobalt toxicity in aquatic species in general and cnidarians in particular remain poorly understood. Herein we investigated cobalt toxicity in a Hydra model from morphological, histological, developmental, and molecular biological perspectives. Hydra, exposed to cobalt (0-60 mg/L), were altered in morphology, histology, and regeneration. Exposure to standardized sublethal doses of cobalt impaired feeding by affecting nematocytes, which in turn affected reproduction. At the cellular level, excessive ROS generation, as the principal mechanism of action, primarily occurred in the lysosomes, which was accompanied by the upregulation of expression of the antioxidant genes SOD, GST, GPx, and G6PD. The number of Hsp70 and FoxO transcripts also increased. Interestingly, the upregulations were higher in the 24-h than in the 48-h time-point group, indicating that ROS overwhelmed the cellular defense mechanisms at the latter time-point. Comet assay revealed DNA damage. Cell cycle analysis indicated the induction of apoptosis accompanied or not by cell cycle arrest. Immunoblot analyses revealed that cobalt treatment triggered mitochondria-mediated apoptosis as inferred from the modulation of the key proteins Bax, Bcl-2, and caspase-3. From this data, we suggest the use of Hydra as a model organism for the risk assessment of heavy metal pollution in aquatic ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Creep fatigue of low-cobalt superalloys: Waspalloy, PM U 700 and wrought U 700

NASA Technical Reports Server (NTRS)

Leis, B. N.; Rungta, R.; Hopper, A. T.

1983-01-01

The influence of cobalt content on the high temperature creep fatigue crack initiation resistance of three primary alloys was evaluated. These were Waspalloy, Powder U 700, and Cast U 700, with cobalt contents ranging from 0 up to 17 percent. Waspalloy was studied at 538 C whereas the U 700 was studied at 760 C. Constraints of the program required investigation at a single strain range using diametral strain control. The approach was phenomenological, using standard low cycle fatigue tests involving continuous cycling tension hold cycling, compression hold cycling, and symmetric hold cycling. Cycling in the absence of or between holds was done at 0.5 Hz, whereas holds when introduced lasted 1 minute. The plan was to allocate two specimens to the continuous cycling, and one specimen to each of the hold time conditions. Data was taken to document the nature of the cracking process, the deformation response, and the resistance to cyclic loading to the formation of small cracks and to specimen separation. The influence of cobalt content on creep fatigue resistance was not judged to be very significant based on the results generated. Specific conclusions were that the hold time history dependence of the resistance is as significant as the influence of cobalt content and increased cobalt content does not produce increased creep fatigue resistance on a one to one basis.

Cobalt Nanoparticle-Embedded Porous Carbon Nanofibers with Inherent N- and F-Doping as Binder-Free Bifunctional Catalysts for Oxygen Reduction and Evolution Reactions.

PubMed

Singhal, Richa; Kalra, Vibha

2017-01-18

Efficient, low-cost, non-precious metal-based, and stable bifunctional electrocatalysts are key to various energy storage and conversion devices such as regenerative fuel cells and metal-air batteries. In this work, we report cobalt nanoparticle-embedded porous carbon nanofibers with inherent N- and F-doping as binder-free bifunctional electrocatalysts with excellent activity for both the oxygen reduction and oxygen evolution reaction (ORR/OER) in an alkaline medium. Single-step electrospinning of a solution of the polymer mixture (carbon precursor) and the cobalt precursor followed by controlled pyrolysis with an intermediate reduction step in H 2 (to reduce cobalt oxides to cobalt) was utilized to synthesize an integrated freestanding catalyst. The fabricated catalyst with effective structural and electronic interaction between the cobalt metal nanoparticles and the N- and F-doped carbon defect sites showed enhanced catalytic properties compared to the benchmark catalysts for ORR and OER (Pt, Ir, and Ru). The ORR potential at the current density of -3 mA cm -2 was 0.81 V RHE and the OER potential at a current density of 10 mA cm -2 was 1.595 V RHE , resulting in a ΔE of only 0.785 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of ionic Co presence on the structural, optical and photocatalytic properties of modified cobalt-titanate nanotubes.

PubMed

Barrocas, B; Silvestre, A J; Rolo, A G; Monteiro, O C

2016-07-21

With the aim of producing materials with enhanced optical and photocatalytic properties, titanate nanotubes (TNTs) modified by cobalt doping (Co-TNT) and by Na(+)→ Co ion-exchange (TNT/Co) were successfully prepared by a hydrothermal method. The influence of the doping level and of the cobalt position in the TNT crystalline structure was studied. Although no perceptible influence of the cobalt ion position on the morphology of the prepared titanate nanotubes was observed, the optical behaviour of the cobalt modified samples is clearly dependent on the cobalt ions either substituting the Ti(4+) ions in the TiO6 octahedra building blocks of the TNT structure (doped samples) or replacing the Na(+) ions between the TiO6 interlayers (ion-exchange samples). The catalytic ability of these materials on pollutant photodegradation was investigated. First, the evaluation of hydroxyl radical formation using the terephthalic acid as a probe was performed. Afterwards, phenol, naphthol yellow S and brilliant green were used as model pollutants. Anticipating real world situations, photocatalytic experiments were performed using solutions combining these pollutants. The results show that the Co modified TNT materials (Co-TNT and TNT/Co) are good catalysts, the photocatalytic performance being dependent on the Co/Ti ratio and on the structural metal location. The Co(1%)-TNT doped sample was the best photocatalyst for all the degradation processes studied.

Graphene/cobalt nanocarrier for hyperthermia therapy and MRI diagnosis.

PubMed

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aminatun,, E-mail: ami-sofijan@yahoo.co.id; Putri, N.S Efinda, E-mail: ami-sofijan@yahoo.co.id; Indriani, Arista, E-mail: ami-sofijan@yahoo.co.id

Cobalt-based alloys are widely used as total hip and knee replacements because of their excellent properties, such as corrosion resistance, fatigue strength and biocompatibility. In this work, cobalt alloys with variation of Cr (28.5; 30; 31.5; 33, and 34.5% wt) have been synthesized by smelting method began with the process of compaction, followed by smelting process using Tri Arc Melting Furnace at 200A. Continued by homogenization process at recrystallization temperature (1250° C) for 3 hours to allow the atoms diffuses and transform into γ phase. The next process is rolling process which is accompanied by heating at 1200° C formore » ± 15 minutes and followed by quenching. This process is repeated until the obtained thickness of ± 1 mm. The evaluated material properties included microstructure, surface morphology, and hardness value. It was shown that microstructure of cobalt alloys with variation of Cr is dominant by γ phase, thus making the entire cobalt alloys have high hardness. It was also shown from the surface morphology of entire cobalt alloys sample indicated the whole process of synthesis that had good solubility were at flat surface area. Hardness value test showed all of cobalt alloys sample had high hardness, just variation of 33% Cr be in the range of ASTMF75, it were 345,24 VHN which is potential to be applied as an implant prosthesis.« less

Inhibition of chlorophyll synthesis and carotenoid accumulation by manganese and cobalt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clairmont, K.B.; Davis, E.; Hagar, W.

1986-05-01

The authors have developed methods for the separation and identification of the major pigments of the photosynthetic apparatus in plants using reversed phase microbore high performance liquid chromatography. Using these methods they have monitored the concentrations of pigments in tissue cultured tobacco callus in the absence and presence of excess manganese and cobalt. Manganese and cobalt were reported to inhibit chlorophyll synthesis in blue green algae. They have found that excess manganese blocks chlorophyll synthesis in tobacco callus also. In the manganese inhibited callus there is an increase in the concentration of protoporphyrin IX- the last common precursor to bothmore » the chlorophyll and heme synthetic pathways. They have found that cobalt also blocks chlorophyll synthesis in tissue cultured tobacco callus, but at a much lower concentration. In addition to the inhibition of chlorophyll synthesis by excess manganese and cobalt, the accumulation of carotenoids is reduced by several orders of magnitude in this tissue. The absence of chlorophyll may prevent assembly of any components of the photosynthetic apparatus in these cells.« less

Evidence of Formation of Superdense Nonmagnetic Cobalt.

PubMed

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

2017-02-03

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.

Impedance measurement of Cobalt doped ZnO Quantum dots

NASA Astrophysics Data System (ADS)

Tiwari, Ram; Kaphle, Amrit; Hari, Parameswar

We investigated structural, thermal and electrical properties of ZnO Quantum dots grown by precipitation method. QDs were spin coated on ITO and annealed at various temperatures ranging from 1000C to 300 0C. ZnO QDs were doped with cobalt for concentration ranging from 0-15%. XRD measurement showed increase in bond length, strain, dislocation density and Cell volume as the doping level varied from 0% to 15%. Impedance Spectroscopy measurements represented by Cole-Cole plot showed reduction in resistance as the cobalt doping concentration increased from 0-15%. Thermal activation energy was obtained by plotting resistivity Vs temperature for doped samples at temperatures from 1000C to 3000C. The thermal activation energy decreased from 85.13meV to 58.21meV as doping increased from 0-15%. Relaxation time was extracted by fitting data to RC model. Relaxation time varied from 61.57 ns to 3.76 ns as the cobalt concentration increased from 0% to 15%. We will also discuss applications of cobalt doped ZnO QDs on improving conversion efficiency of solar cells.

Influence of Cobalt Substitution on the Magnetic Properties of Fe5PB2.

PubMed

Cedervall, Johan; Nonnet, Elise; Hedlund, Daniel; Häggström, Lennart; Ericsson, Tore; Werwiński, Mirosław; Edström, Alexander; Rusz, Ján; Svedlindh, Peter; Gunnarsson, Klas; Sahlberg, Martin

2018-01-16

The substitutional effects of cobalt in (Fe 1-x Co x ) 5 PB 2 have been studied with respect to crystalline structure and chemical order with X-ray diffraction and Mössbauer spectroscopy. The magnetic properties have been determined from magnetic measurements, and density functional theory calculations have been performed for the magnetic properties of both the end compounds, as well as the chemically disordered intermediate compounds. The crystal structure of (Fe 1-x Co x ) 5 PB 2 is tetragonal (space group I4/mcm) with two different metal sites, with a preference for cobalt atoms in the M(2) position (4c) at higher cobalt contents. The substitution also affects the magnetic properties with a decrease of the Curie temperature (T C ) with increasing cobalt content, from 622 to 152 K for Fe 5 PB 2 and (Fe 0.3 Co 0.7 ) 5 PB 2 , respectively. Thus, the Curie temperature is dependent on composition, and it is possible to tune T C to a temperature near room temperature, which is one prerequisite for magnetic cooling materials.

Synthesis and Characterization of Cobalt Substituted Zinc Ferrite Nanoparticles by Microwave Combustion Method.

PubMed

Sundararajan, M; Kennedy, L John; Vijaya, J Judith

2015-09-01

Pure and cobalt doped zinc ferrites were prepared by microwave combustion method using L-arginine as a fuel. The prepared samples were characterized by various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, Fourier transformed infrared (FT-IR) spectroscopy, photoluminescence spectroscopy and UV-Visible diffuse reflectance spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis confirmed the formation of zinc ferrites normal spinel-type structure with an average crystallite sizes in the range, 25.69 nm to 35.68 nm. The lattice parameters decreased as cobalt fraction was increased. The HR-SEM images showed nanoparticles are agglomerated. The estimated band gap energy value was found to decrease with an increase in cobalt content (1.87 to 1.62 eV). Broad visible emissions are observed in the photoluminescence spectra. A gradual increase in the coercivity and saturation magnetization (M(s)) were noted at relatively higher cobalt doping fractions.

Reversible Redox Effect on Gas Permeation of Cobalt Doped Ethoxy Polysiloxane (ES40) Membranes

PubMed Central

Miller, Christopher R.; Wang, David K.; Smart, Simon; Diniz da Costa, João C.

2013-01-01

This work reports the remarkable effect of reversible gas molecular sieving for high temperature gas separation from cobalt doped ethoxy polysiloxane (CoES40) membranes. This effect stemmed from alternating the reducing and oxidising (redox) state of the cobalt particles embedded in the ES40 matrix. The reduced membranes gave the best H2 permeances of 1 × 10−6 mol m−2 s−1 Pa−1 and H2/N2 permselectivities of 65. The reduction process tailored a molecular gap attributed to changes in the specific volume between the reduced cobalt (Co(OH)2 and CoO) particles in the ES40 structure, thus allowing for the increased diffusion of gases. Upon re-oxidation, the tailored molecular gap became constricted as the particles reversed to Co3O4 resulting a lower gas diffusion, particularly for the larger gases ie. CO2 and N2. The ES40 matrix proved to be structurally rigid enough to withstand the reversible redox effect of cobalt particles across multiple cycles. PMID:23571730

Calculation of Distribution Coefficients of Cobalt and Copper in Matte and Slag Phases in Reduction-Vulcanization Process of Copper Converter Slag

NASA Astrophysics Data System (ADS)

Du, Ke; Li, Hongxu; Zhang, Mingming

2017-11-01

Copper and cobalt are two of the most valuable metals that can be recovered from copper converter slag. In the reduction-vulcanization process, copper is reduced before cobalt, while FeS vulcanizes Cu2O into Cu2S and forms the matte phase. The matte phase can dissolve the reduced metals as solvent. In this study, the distribution coefficient of cobalt between metallic cobalt in matte and CoO in slag, namely L Co, was calculated to be 5000-8500 at the reaction temperature of 1600-1700 K, while the distribution coefficient between CoS and CoO, namely L_{Co}^{{^' } }}, was calculated to be between 6 and 8. The distribution coefficient of copper between metallic copper in matte and Cu2O in slag, namely L Cu, was calculated to be in the range of 7500-8500, while the coefficient between Cu2S and Cu2O, namely L_{Cu}^{{^' } }}, was calculated to be in the range of 60,000-75,000.

Tracking the metal of the goblins: cobalt's cycle of use.

PubMed

Harper, E M; Kavlak, G; Graedel, T E

2012-01-17

Cobalt is a vital element in many technological applications, which, together with its increasing end-use in batteries, makes it important to quantify its cycle of use. We have done so for the planet as a whole and for the three principal cobalt-using countries - China, Japan, and the United States - for 2005. Together, China, Japan, and the United States accounted for approximately 65% of the cobalt fabricated and manufactured into end-use products (a total of 37 Gg Co). A time residence model allowed calculations of in-use stock accumulation and recycled and landfilled flows. China had the largest accumulation of in-use stock at some 4.3 Gg Co, over half of which was comprised of consumer battery stock. More than half of the stock accumulation in the United States was estimated to be in aircraft, rocket, and gas turbine engines, with a total in-use stock accumulation of approximately 3 Gg Co. The largest amounts of cobalt landfilled in China, the United States, and the planet were from the "chemical and other uses" category, and Japan's largest landfilled flow was in consumer batteries.

Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage.

PubMed

Begović, Lidija; Mlinarić, Selma; Antunović Dunić, Jasenka; Katanić, Zorana; Lončarić, Zdenko; Lepeduš, Hrvoje; Cesar, Vera

2016-06-01

The effect of two concentrations of cobalt (Co(2+)) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72h after the start of the exposure. Higher concentration of cobalt (1mM) induced growth inhibition while lower concentration (0.01mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co(2+) especially at the higher concentration where decreased electron transport beyond primary quinone acceptor QA(-) and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co(2+) concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals. Copyright © 2016 Elsevier B.V. All rights reserved.

Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application.

PubMed

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.

First iron and cobalt(II) hexabromoclathrochelates: structural, magnetic, redox, and electrocatalytic behavior.

PubMed

Dolganov, Alexander V; Belov, Alexander S; Novikov, Valentin V; Vologzhanina, Anna V; Romanenko, Galina V; Budnikova, Yulia G; Zelinskii, Genrikh E; Buzin, Michail I; Voloshin, Yan Z

2015-02-07

Template condensation of dibromoglyoxime with n-butylboronic acid on the corresponding metal ion as a matrix under vigorous reaction conditions afforded iron and cobalt(ii) hexabromoclathrochelates. The paramagnetic cobalt clathrochelate was found to be a low-spin complex at temperatures below 100 K, with a gradual increase in the effective magnetic moment at higher temperatures due to the temperature 1/2↔3/2 spin crossover and a gap caused by the structure phase transition. The multitemperature X-ray and DSC studies of this complex and its iron(ii)-containing analog also showed temperature structural transitions. The variation of an encapsulated metal ion's radius, electronic structure and spin state caused substantial differences in the geometry of its coordination polyhedron; these differences increase with the decrease in temperature due to Jahn-Teller distortion of the encapsulated cobalt(ii) ion with an electronic configuration d(7). As follows from CV and GC data, these cage iron and cobalt complexes undergo both oxidation and reduction quasireversibly, and showed an electrocatalytic activity for hydrogen production in different producing systems.

Open-Loop Flight Testing of COBALT Navigation and Sensor Technologies for Precise Soft Landing

NASA Technical Reports Server (NTRS)

Carson, John M., III; Restrepo, Caroline I.; Seubert, Carl R.; Amzajerdian, Farzin; Pierrottet, Diego F.; Collins, Steven M.; O'Neal, Travis V.; Stelling, Richard

2017-01-01

An open-loop flight test campaign of the NASA COBALT (CoOperative Blending of Autonomous Landing Technologies) payload was conducted onboard the Masten Xodiac suborbital rocket testbed. The payload integrates two complementary sensor technologies that together provide a spacecraft with knowledge during planetary descent and landing to precisely navigate and softly touchdown in close proximity to targeted surface locations. The two technologies are the Navigation Doppler Lidar (NDL), for high-precision velocity and range measurements, and the Lander Vision System (LVS) for map-relative state esti- mates. A specialized navigation filter running onboard COBALT fuses the NDL and LVS data in real time to produce a very precise Terrain Relative Navigation (TRN) solution that is suitable for future, autonomous planetary landing systems that require precise and soft landing capabilities. During the open-loop flight campaign, the COBALT payload acquired measurements and generated a precise navigation solution, but the Xodiac vehicle planned and executed its maneuvers based on an independent, GPS-based navigation solution. This minimized the risk to the vehicle during the integration and testing of the new navigation sensing technologies within the COBALT payload.

Cobalt poisoning

MedlinePlus

... This type of implant is an artificial hip socket that is created by fitting a metal ball ... particles (ions) can get released into the hip socket and sometimes the bloodstream, causing cobalt toxicity. This ...

[(S)-1-Carbamoylethyl]bis(dimethylglyoximato-kappa2N,N')[(S)-1-phenylethylamine]cobalt(III) and bis(dimethylglyoximato-kappa2N,N')[(R)-1-(N-methylcarbamoyl)ethyl][(R)-1-phenylethylamine]cobalt(III) monohydrate.

PubMed

Orisaku, Keiko Komori; Hagiwara, Mieko; Ohgo, Yoshiki; Arai, Yoshifusa; Ohgo, Yoshiaki

2005-04-01

The title complexes, [Co(C3H6NO)(C4H7N2O2)2(C8H11N)] and [Co(C4H8NO)(C4H7N2O2)2(C8H11N)].H2O, were resolved from [(RS)-1-carbamoylethyl]bis(dimethylglyoximato)[(S)-1-phenylethylamine]cobalt(III) and bis(dimethylglyoximato)[(RS)-1-(N-methylcarbamoyl)ethyl][(R)-1-phenylethylamine]cobalt(III), respectively, and their crystal structures were determined in order to reveal the absolute configuration of the major enantiomer produced in the photoisomerization of each series of 2-carbamoylethyl and 2-(N-methylcarbamoyl)ethyl cobaloxime complexes.

Characterization of the interface interaction of cobalt on top of copper- and iron-phthalocyanine.

PubMed

Schmitt, Felix; Sauther, Jens; Lach, Stefan; Ziegler, Christiane

2011-05-01

The electronic structure of the interface between ferromagnetic cobalt and the organic semiconductors copper- (CuPc) and iron-phthalocyanine (FePc) was investigated by means of photoemission spectroscopy (UPS, IPES, and XPS). These metal-phthalocyanine (MePc) molecules have an open shell structure and are known to show promising properties for their use in organic spintronics. In spintronic devices, the interface between ferromagnetic electrode and the organic layer determines the spin injection properties and is hence important for the quality of, e.g., a possible spin-valve device. For this purpose, cobalt was deposited onto the MePcs, such as in devices with ferromagnetic top contacts. The reported investigations reveal a diffusion of cobalt into the organic layers and chemical reactions at the interface.

Metal-metal bond lengths in complexes of transition metals*

PubMed Central

Pauling, Linus

1976-01-01

In complexes of the transition metals containing clusters of metal atoms the cobalt-cobalt bond lengths are almost always within 1 pm of the single-bond value 246 pm given by the enneacovalent radius of cobalt, whereas most of the observed iron-iron bond lengths are significantly larger than the single-bond value 248 pm, the mean being 264 pm, which corresponds to a half-bond. A simple discussion of the structures of these complexes based on spd hybrid orbitals, the electroneutrality principle, and the partial ionic character of bonds between unlike atoms leads to the conclusion that resonance between single bonds and no-bonds would occur for iron and its congeners but not for cobalt and its congeners, explaining the difference in the bond lengths. PMID:16592368

Cobalt chloride administration in athletes: a new perspective in blood doping?

PubMed

Lippi, G; Franchini, M; Guidi, G C

2005-11-01

Blood doping is an illegal and unfair way of enhancing athletic performance by increasing the oxygen carrying capacity of the blood. Currently used methods usually involve stimulation of erythropoiesis. Gene therapy targeting the hypoxia inducible factor pathway may be an attractive alternative to traditional blood doping techniques. Hypoxia activates a large number of genes with essential roles in cell and tissue adaptation to low oxygen. Cobalt chloride is a well established chemical inducer of hypoxia-like responses such as erythropoiesis. Cobalt supplementation is not banned and therefore would not be detected by current anti-doping testing. Although there is as yet no direct or anecdotal evidence of cobalt chloride administration to athletes, its use should be warned against as being not only unfair but potentially dangerous.

Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area

PubMed Central

Bryngelsson, Ing-Liss; Pettersson, Carin; Husby, Bente; Arvidsson, Helena; Westberg, Håkan

2016-01-01

Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose–response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m−3, range <0.023–3.0mg m−3) and below the present Swedish occupational exposure limit (OEL) of 10mg m−3. The cobalt levels were low as well (AM 0.0030mg m−3, range 0.000028–0.056mg m−3) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m−3. For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m−3 by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm−3) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm2·cm−3) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle number. Linear regression analysis of the same data showed statistically significant regression coefficients only for the mass-based aerosol measures. Similar results were seen for rank correlation in the stationary rig, and linear regression analysis implied significant correlation for mass-based and particle surface area measures. The mass-based air concentration levels of cobalt and tungsten in the hard metal plant in our study were low compared to Swedish OELs. Particle number and particle surface area concentrations were in the same order of magnitude as for other industrial settings. Regression analysis implied the use of stationary determined mass-based and particle surface area aerosol concentration as proxies for various exposure measures in our study. PMID:27143598

The Idaho cobalt belt

USGS Publications Warehouse

Bookstrom, Arthur A.

2013-01-01

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

Electrochemical synthesis of porous cobalt nanowall arrays

NASA Astrophysics Data System (ADS)

He, Wei; Gao, Peng; Chu, Lei; Yin, Ligen; Li, Zhen; Xie, Yi

2006-07-01

Porous cobalt nanowall arrays have been prepared by electrochemical deposition of mono-precursor [Co(NH3)5Cl]Cl2 on copper substrates. Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) investigations of the surface properties indicate that the resulting porous nanomaterials possess high surface area and uniform pore size distribution, which implies potential applications in some fields, such as catalysis, energy, and magnetic data storage devices. The magnetism measurements of the porous cobalt nanowall arrays take on a good ferromagnetic behaviour with enhanced coercivity (Hc).

Mobilization and Defense Management Technical Reports Series. Critical Non-Fuel Minerals in Mobilization with Case Studies on Cobalt and Titanium.

DTIC Science & Technology

1983-04-01

Affairs Comarce Science and Transportation House Comittees Science Rsearch and Tecnology Interstate and Foreign Commrce hnting, Finance, and Urban...cobalt include cutting tools, jet engine parts, electrical devices, permanent magnets, catalysts, paint pigmnts, and paint dryers . 1 The U.S. is the...in the superalloy field. Subtittesfor cobalt as a catalyst or as a dryer in paints are usually not effective. In dryer iUcations,, manganame and lead

Carbonate fuel cell anodes

DOEpatents

Donado, R.A.; Hrdina, K.E.; Remick, R.J.

1993-04-27

A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process is described for production of the lithium ferrite containing anode by slipcasting.

Carbonate fuel cell anodes

DOEpatents

Donado, Rafael A.; Hrdina, Kenneth E.; Remick, Robert J.

1993-01-01

A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process for production of the lithium ferrite containing anode by slipcasting.

Metallic transfer between metals in sliding contact examined by auger emission spectroscopy

NASA Technical Reports Server (NTRS)

Pepper, S. V.

1972-01-01

Metallic transfer between polycrystalline metals in sliding contact was examined. Hemispherical riders of iron, nickel, and cobalt were slid on tungsten, tantalum, niobium, and molybdenum disks in ultrahigh vacuum. Auger emission spectroscopy was used to monitor the elemental composition of the disk surfaces. Iron, nickel, and cobalt transferred to tungsten, whereas only cobalt transferred to tantalum, niobium, and molybdenum. The results of this investigation are discussed in terms of the cohesive energy and strain hardening characteristics of the specimen materials.

Biologically Assembled Quantum Electronic Arrays

DTIC Science & Technology

2013-06-07

characterizing the NP arrays. Theory of gate-tunable exchange coupling in the case of cobalt NP on graphene . Used Spin-density-functional theory and...polarization. We can estimate this field using the material parameters for Cobalt , which gives B neEo:N~ M;r; "󈧶 T zrv M M "’ m s s Here N1 is the...minority spin density of states at the Fermi surface for Cobalt , M5 is its saturation magnetization, while M:x is the x-component of the magnetization

Structure, Bonding and Surface Chemistry of Metal Oxide Nanoclusters

DTIC Science & Technology

2015-06-23

studies to cobalt and chromium oxides and to both oxides and pure metal clusters of aluminum, using acetonitrile as the ligand. The chromium solutions...seen in molecular beam experiments. The cobalt oxide sample produced a blue solution, and mass spectra had a single main peak at 551 amu. Mass...of cobalt and nickel oxide cluster cations," J. Phys. Chem. A 116, 5398-5404 (2012). DOI: 10.1021/jp302560p. 4. A. M. Ricks, A. D. Brathwaite, M

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jha, Manis Kumar, E-mail: mkjha@nmlindia.org; Kumari, Anjan; Jha, Amrita Kumari

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 increasingmore » 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.« less

Responses of two scleractinian corals to cobalt pollution and ocean acidification.

PubMed

Biscéré, Tom; Rodolfo-Metalpa, Riccardo; Lorrain, Anne; Chauvaud, Laurent; Thébault, Julien; Clavier, Jacques; Houlbrèque, Fanny

2015-01-01

The effects of ocean acidification alone or in combination with warming on coral metabolism have been extensively investigated, whereas none of these studies consider that most coral reefs near shore are already impacted by other natural anthropogenic inputs such as metal pollution. It is likely that projected ocean acidification levels will aggravate coral reef health. We first investigated how ocean acidification interacts with one near shore locally abundant metal on the physiology of two major reef-building corals: Stylophora pistillata and Acropora muricata. Two pH levels (pHT 8.02; pCO2 366 μatm and pHT 7.75; pCO2 1140 μatm) and two cobalt concentrations (natural, 0.03 μg L-1 and polluted, 0.2 μg L-1) were tested during five weeks in aquaria. We found that, for both species, cobalt input decreased significantly their growth rates by 28% while it stimulated their photosystem II, with higher values of rETRmax (relative Electron Transport Rate). Elevated pCO2 levels acted differently on the coral rETRmax values and did not affect their growth rates. No consistent interaction was found between pCO2 levels and cobalt concentrations. We also measured in situ the effect of higher cobalt concentrations (1.06 ± 0.16 μg L-1) on A. muricata using benthic chamber experiments. At this elevated concentration, cobalt decreased simultaneously coral growth and photosynthetic rates, indicating that the toxic threshold for this pollutant has been reached for both host cells and zooxanthellae. Our results from both aquaria and in situ experiments, suggest that these coral species are not particularly sensitive to high pCO2 conditions but they are to ecologically relevant cobalt concentrations. Our study reveals that some reefs may be yet subjected to deleterious pollution levels, and even if no interaction between pCO2 levels and cobalt concentration has been found, it is likely that coral metabolism will be weakened if they are subjected to additional threats such as temperature increase, other heavy metals, and eutrophication.

Do cobalt and chromium levels predict osteolysis in metal-on-metal total hip arthroplasty?

PubMed

Renner, Lisa; Schmidt-Braekling, Tom; Faschingbauer, Martin; Boettner, Friedrich

2016-12-01

Serum metal ions are part of the regular follow-up routine of patients with metal-on-metal total hip arthroplasties (MoM-THA). Increased cobalt levels have been suggested to indicate implant failure and corrosion. (1) Is there a correlation between the size of the osteolysis measured on a CT scan and metal ion levels? (2) Can metal ion levels predict the presence of osteolysis in MoM-THA? (3) Are cobalt and chromium serum levels or the cobalt-chromium-ratio diagnostic for osteolysis? CT scans of patients (n = 75) with a unilateral MoM-THA (Birmingham Hip System, Smith & Nephew, TN, USA) implanted by a single surgeon were reviewed to determine the presence of osteolysis. Statistical analysis was performed to detect its association with metal ion levels at the time of the imaging exam. The incidence of osteolysis was the same in men and women (35.6 vs 35.7 %). The cobalt-chromium-ratio correlates with the size of the osteolysis on the CT scan and the femoral component size in the overall study population (p = 0.050, p = 0.001) and in men (p = 0.002, p = 0.001) but not in women (p = 0.312, p = 0.344). The AUC for the cobalt-chromium-ratio to detect osteolysis was 0.613 (p = 0.112) for the overall population, 0.710 for men (p = 0.021) and 0.453 (p = 0.684) for women. The data suggest that a cut off level of 1.71 for the cobalt-chromium-ratio has a sensitivity of 62.5 % and specificity of 72.4 % to identify male patients with osteolysis. The disproportional increase of cobalt over chromium, especially in male patients with large component sizes can not be explained by wear alone and suggests that other processes (corrosion) might contribute to metal ion levels and might be more pronounced in patients with larger component sizes.

NASA Precision Landing Technologies Completes Initial Flight Tests on Vertical Testbed Rocket

NASA Image and Video Library

2017-04-19

This 2-minute, 40-second video shows how over the past 5 weeks, NASA and Masten Space Systems teams have prepared for and conducted sub-orbital rocket flight tests of next-generation lander navigation technology through the CoOperative Blending of Autonomous Landing Technologies (COBALT) project. The COBALT payload was integrated onto Masten’s rocket, Xodiac. The Xodiac vehicle used the Global Positioning System (GPS) for navigation during this first campaign, which was intentional to verify and refine COBALT system performance. The joint teams conducted numerous ground verification tests, made modifications in the process, practiced and refined operations’ procedures, conducted three tether tests, and have now flown two successful free flights. This successful, collaborative campaign has provided the COBALT and Xodiac teams with the valuable performance data needed to refine the systems and prepare them for the second flight test campaign this summer when the COBALT system will navigate the Xodiac rocket to a precision landing. The technologies within COBALT provide a spacecraft with knowledge during entry, descent, and landing that enables it to precisely navigate and softly land close to surface locations that have been previously too risky to target with current capabilities. The technologies will enable future exploration destinations on Mars, the moon, Europa, and other planets and moons. The two primary navigation components within COBALT include the Langley Research Center’s Navigation Doppler Lidar, which provides ultra-precise velocity and line-of-sight range measurements, and Jet Propulsion Laboratory’s Lander Vision System (LVS), which provides navigation estimates relative to an existing surface map. The integrated system is being flight tested onboard a Masten suborbital rocket vehicle called Xodiac. The COBALT project is led by the Johnson Space Center, with funding provided through the Game Changing Development, Flight Opportunities program, and Advanced Exploration Systems programs. Based at NASA’s Armstrong Flight Research Center in Edwards, CA, the Flight Opportunities program funds technology development flight tests on commercial suborbital space providers of which Masten is a vendor. The program has previously tested the LVS on the Masten rocket and validated the technology for the Mars 2020 rover.

Responses of Two Scleractinian Corals to Cobalt Pollution and Ocean Acidification

PubMed Central

Biscéré, Tom; Rodolfo-Metalpa, Riccardo; Lorrain, Anne; Chauvaud, Laurent; Thébault, Julien; Clavier, Jacques; Houlbrèque, Fanny

2015-01-01

The effects of ocean acidification alone or in combination with warming on coral metabolism have been extensively investigated, whereas none of these studies consider that most coral reefs near shore are already impacted by other natural anthropogenic inputs such as metal pollution. It is likely that projected ocean acidification levels will aggravate coral reef health. We first investigated how ocean acidification interacts with one near shore locally abundant metal on the physiology of two major reef-building corals: Stylophora pistillata and Acropora muricata. Two pH levels (pHT 8.02; pCO2 366 μatm and pHT 7.75; pCO2 1140 μatm) and two cobalt concentrations (natural, 0.03 μg L-1 and polluted, 0.2 μg L-1) were tested during five weeks in aquaria. We found that, for both species, cobalt input decreased significantly their growth rates by 28% while it stimulated their photosystem II, with higher values of rETRmax (relative Electron Transport Rate). Elevated pCO2 levels acted differently on the coral rETRmax values and did not affect their growth rates. No consistent interaction was found between pCO2 levels and cobalt concentrations. We also measured in situ the effect of higher cobalt concentrations (1.06 ± 0.16 μg L-1) on A. muricata using benthic chamber experiments. At this elevated concentration, cobalt decreased simultaneously coral growth and photosynthetic rates, indicating that the toxic threshold for this pollutant has been reached for both host cells and zooxanthellae. Our results from both aquaria and in situ experiments, suggest that these coral species are not particularly sensitive to high pCO2 conditions but they are to ecologically relevant cobalt concentrations. Our study reveals that some reefs may be yet subjected to deleterious pollution levels, and even if no interaction between pCO2 levels and cobalt concentration has been found, it is likely that coral metabolism will be weakened if they are subjected to additional threats such as temperature increase, other heavy metals, and eutrophication. PMID:25849317

Weight of Polyethylene Wear Particles is Similar in TKAs with Oxidized Zirconium and Cobalt-chrome Prostheses

PubMed Central

Kim, Jun-Shik; Huh, Wansoo; Lee, Kwang-Hoon

2009-01-01

Background The greater lubricity and resistance to scratching of oxidized zirconium femoral components are expected to result in less polyethylene wear than cobalt-chrome femoral components. Questions/purposes We examined polyethylene wear particles in synovial fluid and compared the weight, size (equivalent circle diameter), and shape (aspect ratio) of polyethylene wear particles in knees with an oxidized zirconium femoral component with those in knees with a cobalt-chrome femoral component. Patients and Methods One hundred patients received an oxidized zirconium femoral component in one knee and a cobalt-chrome femoral component in the other. There were 73 women and 27 men with a mean age of 55.6 years (range, 44–60 years). The minimum followup was 5 years (mean, 5.5 years; range, 5–6 years). Polyethylene wear particles were analyzed using thermogravimetric methods and scanning electron microscopy. Results The weight of polyethylene wear particles produced at the bearing surface was 0.0223 ± 0.0054 g in 1 g synovial fluid in patients with an oxidized zirconium femoral component and 0.0228 ± 0.0062 g in patients with a cobalt-chrome femoral component. Size and shape of polyethylene wear particles were 0.59 ± 0.05 μm and 1.21 ± 0.24, respectively, in the patients with an oxidized zirconium femoral component and 0.52 ± 0.03 μm and 1.27 ± 0.31, respectively, in the patients with a cobalt-chrome femoral component. Knee Society knee and function scores, radiographic results, and complication rate were similar between the knees with an oxidized zirconium and cobalt-chrome femoral component. Conclusions The weight, size, and shape of polyethylene wear particles were similar in the knees with an oxidized zirconium and a cobalt-chrome femoral component. We found the theoretical advantages of this surface did not provide the actual advantage. Level of Evidence Level I, therapeutic study. See the guidelines for Authors for a complete description of levels of evidence. PMID:19949906

Recovery of Silver and Cobalt from Laboratory Wastes.

ERIC Educational Resources Information Center

Foust, Donald F.

1984-01-01

Procedures for recovering silver and cobalt from laboratory wastes (including those resulting from student experiments) are presented. The procedures are generally applicable since only common, inexpensive laboratory reagents are needed. (JN)

Cobalt Oxide Hollow Nanoparticles Derived by Bio-Templating

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo; Choi, Sang H.; Lillehei, Peter T.; Chu, Sang-Hyon; King, Glen C.; Watt, Gerald D.

2005-01-01

We present here the first fabrication of hollow cobalt oxide nanoparticles produced by a protein-regulated site-specific reconstitution process in aqueous solution and describe the metal growth mechanism in the ferritin interior.

Differences in highly cross-linked polyethylene wear between zirconia and cobalt-chromium femoral heads in Japanese patients: a prospective, randomized study.

PubMed

Kawate, Kenji; Ohmura, Tetsuji; Kawahara, Ikuo; Tamai, Katsuya; Ueha, Tomoyuki; Takemura, Kazuo

2009-12-01

The purpose of this study was to compare highly cross-linked polyethylene wear between the zirconia head and the cobalt-chromium head in Japanese patients. A prospective, randomized study was performed to evaluate the outcomes in 32 hips that had zirconia heads and in 30 hips that had cobalt-chromium heads. The mean follow-up periods of both groups were same (5 years). There were no significant differences between the zirconia head and the cobalt-chromium head in the mean polyethylene linear wear per year and the mean volumetric polyethylene wear per year in the steady phase. This study indicates that zirconia head offers no benefits over metal head in terms of wear reduction at 5 years in Japanese patients who have lightweight and thin polyethylene liners.

Synthesis and characterization of α-cobalt hydroxide nanobelts

NASA Astrophysics Data System (ADS)

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.

Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.

PubMed

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. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Electrochemical process for electrode material of spent lithium ion batteries.

PubMed

Prabaharan, G; Barik, S P; Kumar, N; Kumar, L

2017-10-01

Electrochemical method for recovering cobalt and manganese from electrode materials of spent lithium ion batteries was studied. Electrochemical leaching of cobalt and manganese from electrode material was optimized by varying different process parameters such as time, acid concentration and current density. Both cobalt and manganese could effectively be leached out at a current density of 400A/m 2 in 3h using 2M sulphuric acid. In the subsequent study, the metallic cobalt and electrolytic manganese dioxides was recovered from the leach liquor at 200A/m 2 , pH 2-2.5 and 90°C after removing aluminum. The commercial feasibility of the study was tested in pilot scale. Overall recovery of Co, Cu and Mn was above 96%, 97% and 99%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cobalt Modification of Thin Rutile Films Magnetron-Sputtered in Vacuum

NASA Astrophysics Data System (ADS)

Afonin, N. N.; Logacheva, V. A.

2018-04-01

Using X-ray phase analysis, atomic force microscopy, and secondary ion mass-spectrometry, the phase formation and component distribution in a Co-TiO2 film system have been investigated during magnetron sputtering of the metal on the oxide and subsequent vacuum annealing. It has been found that cobalt diffuses deep into titanium oxide to form complex oxides CoTi2O5 and CoTiO3. A mechanism behind their formation at grain boundaries throughout the thickness of the TiO2 film is suggested. It assumes the reactive diffusion of cobalt along grain boundaries in the oxide. A quantitative model of reactive interdiffusion in a bilayer polycrystalline metal-oxide film system with limited solubility of components has been developed. The individual diffusion coefficients of cobalt and titanium have been determined in the temperature interval 923-1073 K.

Functionalized Natural Carbon-Supported Nanoparticles as Excellent Catalysts for Hydrocarbon Production.

PubMed

Sun, Jian; Guo, Lisheng; Ma, Qingxiang; Gao, Xinhua; Yamane, Noriyuki; Xu, Hengyong; Tsubaki, Noritatsu

2017-02-01

We report a one-pot and eco-friendly synthesis of carbon-supported cobalt nanoparticles, achieved by carbonization of waste biomass (rice bran) with a cobalt source. The functionalized biomass provides carbon microspheres as excellent catalyst support, forming a unique interface between hydrophobic and hydrophilic groups. The latter, involving hydroxyl and amino groups, can catch much more active cobalt nanoparticles on surface for Fischer-Tropsch synthesis than chemical carbon. The loading amount of cobalt on the final catalyst is much higher than that prepared with a chemical carbon source, such as glucose. The proposed concept of using a functionalized natural carbon source shows great potential compared with conventional carbon sources, and will be meaningful for other fields concerning carbon support, such as heterogeneous catalysis or electrochemical fields. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

RNA isolation and fractionation with compaction agents

NASA Technical Reports Server (NTRS)

Murphy, J. C.; Fox, G. E.; Willson, R. C.

2001-01-01

A new approach to the isolation of RNA from bacterial lysates employs selective precipitation by compaction agents, such as hexammine cobalt and spermidine. Using 3.5 mM hexammine cobalt, total RNA can be selectively precipitated from a cell lysate. At a concentration of 2 mM hexammine cobalt, rRNA can be fractionated from low molecular weight RNA. The resulting RNA mixture is readily resolved to pure 5S and mixed 16S/23S rRNA by nondenaturing anion-exchange chromatography. Using a second stage of precipitation at 8 mM hexammine cobalt, the low molecular weight RNA fraction can be isolated by precipitation. Compaction precipitation was also applied to the purification of an artificial stable RNA derived from Escherichia coli 5S rRNA and to the isolation of an Escherichia coli-expressed ribozyme. Copyright 2001 Academic Press.

Assessment of skin exposure to nickel, chromium and cobalt by acid wipe sampling and ICP-MS.

PubMed

Lidén, Carola; Skare, Lizbet; Lind, Birger; Nise, Gun; Vahter, Marie

2006-05-01

There is a great need to accurately assess skin exposure to contact allergens. We have developed a technique for assessment of skin exposure to nickel, chromium and cobalt using acid wipe sampling by cellulose wipes with 1% nitric acid. Chemical analysis was performed by inductively coupled plasma mass spectrometry (ICP-MS). The recovery of nickel, chromium and cobalt from arms and palms was 93%. The analytical result is expressed in terms of mass per unit area (microg/cm(2)). The developed acid wipe sampling technique is suitable for determination of nickel, chromium and cobalt deposited on the skin. The technique may be used in workplace studies, in studies of individuals in the general population, in dermatitis patients, in identification of risk groups, as well as in developing preventive strategies and in follow-up after intervention.

Electronic structure of cobalt doped CdSe quantum dots using soft X-ray spectroscopy

DOE PAGES

Wright, Joshua T.; Su, Dong; van Buuren, Tony; ...

2014-08-21

Here, the electronic structure and magnetic properties of cobalt doped CdSe quantum dots (QDs) are studied using electron microscopy, soft X-ray spectroscopy, and magnetometry. Magnetometry measurements suggest these QDs are superparamagnetic, contrary to a spin-glass state observed in the bulk analogue. Electron microscopy shows well formed QDs, but with cobalt existing as doped into the QD and as unreacted species not contained in the QD. X-ray absorption measurements at the Co L3-edge suggest that changes in spectra features as a function of particle size can be described considering combination of a cobalt ion in a tetrahedral crystal field and anmore » octahedrally coordinated (impurity) phase. With decreasing particle sizes, the impurity phase increases, suggesting that small QDs can be difficult to dope.« less

Growth of single-crystalline cobalt silicide nanowires and their field emission property.

PubMed

Lu, Chi-Ming; Hsu, Han-Fu; Lu, Kuo-Chang

2013-07-03

In this work, cobalt silicide nanowires were synthesized by chemical vapor deposition processes on Si (100) substrates with anhydrous cobalt chloride (CoCl2) as precursors. Processing parameters, including the temperature of Si (100) substrates, the gas flow rate, and the pressure of reactions were varied and studied; additionally, the physical properties of the cobalt silicide nanowires were measured. It was found that single-crystal CoSi nanowires were grown at 850°C ~ 880°C and at a lower gas flow rate, while single-crystal Co2Si nanowires were grown at 880°C ~ 900°C. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with field emission measurements demonstrates that CoSi nanowires are attractive choices for future applications in field emitters.

Correlation between Fischer-Tropsch catalytic activity and composition of catalysts

PubMed Central

2011-01-01

This paper presents the synthesis and characterization of monometallic and bimetallic cobalt and iron nanoparticles supported on alumina. The catalysts were prepared by a wet impregnation method. Samples were characterized using temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), CO-chemisorption, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM-EDX) and N2-adsorption analysis. Fischer-Tropsch synthesis (FTS) was carried out in a fixed-bed microreactor at 543 K and 1 atm, with H2/CO = 2 v/v and space velocity, SV = 12L/g.h. The physicochemical properties and the FTS activity of the bimetallic catalysts were analyzed and compared with those of monometallic cobalt and iron catalysts at similar operating conditions. H2-TPR analysis of cobalt catalyst indicated three temperature regions at 506°C (low), 650°C (medium) and 731°C (high). The incorporation of iron up to 30% into cobalt catalysts increased the reduction, CO chemisorption and number of cobalt active sites of the catalyst while an opposite trend was observed for the iron-riched bimetallic catalysts. The CO conversion was 6.3% and 4.6%, over the monometallic cobalt and iron catalysts, respectively. Bimetallic catalysts enhanced the CO conversion. Amongst the catalysts studied, bimetallic catalyst with the composition of 70Co30Fe showed the highest CO conversion (8.1%) while exhibiting the same product selectivity as that of monometallic Co catalyst. Monometallic iron catalyst showed the lowest selectivity for C5+ hydrocarbons (1.6%). PMID:22047220

Catalytic Hydrogenation Activity and Electronic Structure Determination of Bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes

PubMed Central

Yu, Renyuan Pony; Darmon, Jonathan M.; Milsmann, Carsten; Margulieux, Grant W.; E. Stieber, S. Chantal; DeBeer, Serena

2013-01-01

The bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, (iPrCNC)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 °C and 4 atm of H2 pressure, (iPrCNC)CoCH3 is an effective pre-catalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, (iPrCNC)CoH was accomplished by hydrogenation of (iPrCNC)CoCH3. Over the course of 3 hours at 22 °C, migration of the metal-hydride to the 4-position of the pyridine ring yielded (4-H2-iPrCNC)CoN2. Similar alkyl migration was observed upon treatment of (iPrCNC)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redoxactive, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2-ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity and suggest a wide family of pyridine-based pincers may also be redox active. PMID:23968297

Catalytic hydrogenation activity and electronic structure determination of bis(arylimidazol-2-ylidene)pyridine cobalt alkyl and hydride complexes.

PubMed

Yu, Renyuan Pony; Darmon, Jonathan M; Milsmann, Carsten; Margulieux, Grant W; Stieber, S Chantal E; DeBeer, Serena; Chirik, Paul J

2013-09-04

The bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, ((iPr)CNC)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 °C and 4 atm of H2 pressure, ((iPr)CNC)CoCH3 is an effective precatalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene, and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, ((iPr)CNC)CoH, was accomplished by hydrogenation of ((iPr)CNC)CoCH3. Over the course of 3 h at 22 °C, migration of the metal hydride to the 4-position of the pyridine ring yielded (4-H2-(iPr)CNC)CoN2. Similar alkyl migration was observed upon treatment of ((iPr)CNC)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redox-active, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic, and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2-ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity, and suggest that a wide family of pyridine-based pincers may also be redox-active.

Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

DOE PAGES

Liang, H. Winnie; Kroll, Thomas; Nordlund, Dennis; ...

2016-12-30

The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ –) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described asmore » a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ – in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.« less

Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, H. Winnie; Kroll, Thomas; Nordlund, Dennis

The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ –) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described asmore » a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ – in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.« less

Part I. Cobalt thiolate complexes modeling the active site of cobalt nitrile hydratase. Part II. Formation of inorganic nanoparticles on protein scaffolding in Escherichia coli glutamine synthetase

NASA Astrophysics Data System (ADS)

Kung, Irene Yuk Man

Part I. A series of novel cobalt dithiolate complexes with mixed imine/amine ligand systems is presented here as electronic and structural models for the active site in the bacterial enzyme class, nitrile hydratase (NHase). Pentadentate cobalt(II) complexes with S2N 3 ligand environments are first studied as precursors to the more relevant cobalt(III) complexes. Adjustment of the backbone length by removal of a methylene group increases the reactivity of the system; whereas reduction of the two backbone imine bonds to allow free rotation about those bonds may decrease reactivity. Reactivity change due to the replacement of the backbone amine proton with a more sterically challenging methyl group is not yet clear. Upon oxidation, the monocationic pentadentate cobalt(III) complex, 1b, shows promising reactivity similar to that of NHase. The metal's open coordination site allows reversible binding of the endogenous, monoanionic ligands, N 3- and NCS-. Oxygenation of the thiolate sulfur atoms by exposure to O2 and H2O 2 produces sulfenate and sulfinate ligands in complex 8, which resembles the crystal structure of "deactivated" Fe NHase. However, its lack of reactivity argues against the oxygenated enzyme structure as the active form. Six-coordinate cobalt(III) complexes with S2N4 amine/amine ligand systems are also presented as analogues of previously reported iron(III) compounds, which mimic the spectroscopic properties of Fe NHase. The cobalt complexes do not seem to similarly model Co NHase. However, the S = 0 cobalt(III) center can be spectroscopically silent and difficult to detect, making comparison with synthetic models using common techniques hard. Part II. Dodecameric Escherichia coli glutamine synthetase mutant, E165C, stacks along its six-fold axis to produce tubular nanostructures in the presence of some divalent metal ions, as does the wild type enzyme. The centrally located, engineered Cys-165 residues appear to bind to various species and may serve as scaffolding for inorganic mineralization. US nanoclusters of discreet size seem to grow in the presence of E165C in aqueous solution spontaneously. Commercially available mono(maleimido)undecagold seem to bind only to E165C through the reactive cysteine side chains. Reduction of Au3+ to elemental gold in solution with E165C, generates long, linear structures of approximately 100-nm diameter.

Facile Synthesis of Ultrathin Nickel-Cobalt Phosphate 2D Nanosheets with Enhanced Electrocatalytic Activity for Glucose Oxidation.

PubMed

Shu, Yun; Li, Bing; Chen, Jingyuan; Xu, Qin; Pang, Huan; Hu, Xiaoya

2018-01-24

Two-dimensional (2D) ultrathin nickel-cobalt phosphate nanosheets were synthesized using a simple one-step hydrothermal method. The morphology and structure of nanomaterials synthesized under different Ni/Co ratios were investigated by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Moreover, the influence of nanomaterials' structure on the electrochemical performance for glucose oxidation was investigated. It is found that the thinnest nickel-cobalt phosphate nanosheets synthesized with a Ni/Co ratio of 2:5 showed the best electrocatalytic activity for glucose oxidation. Also, the ultrathin nickel-cobalt phosphate nanosheet was used as an electrode material to construct a nonenzymatic electrochemical glucose sensor. The sensor showed a wide linear range (2-4470 μM) and a low detection limit (0.4 μM) with a high sensitivity of 302.99 μA·mM -1 ·cm -2 . Furthermore, the application of the as-prepared sensor in detection of glucose in human serum was successfully demonstrated. These superior performances prove that ultrathin 2D nickel-cobalt phosphate nanosheets are promising materials in the field of electrochemical sensing.

Nickel and cobalt release from children's toys purchased in Denmark and the United States.

PubMed

Jensen, Peter; Hamann, Dathan; Hamann, Carsten R; Jellesen, Morten S; Jacob, Sharon E; Thyssen, Jacob P

2014-01-01

Nickel is the most common allergen detected by patch testing in children. There is an increasing number of cases in children who have not had exposure to piercing. Although the clinical relevance of nickel patch test reactions in children is sometimes uncertain, continued vigilance to identify new sources of nickel exposure in this age group is important. Recent case reports have described allergic nickel contact dermatitis in children following exposure to toys, but the magnitude of this problem is unknown. The aim of this study was to evaluate nickel and cobalt release from children's toys. We purchased 212 toys in 18 different retail and online stores in the United States and Denmark. Nickel and cobalt release was tested using the dimethylglyoxime and cobalt screening spot tests. A total of 73 toys (34.4%) released nickel, and none released cobalt. Toys are a commonly overlooked source of nickel exposure and sensitization. Therefore, dermatologists, allergists, and pediatricians should consider the role of toys in their evaluation of children with dermatitis, and the parents of children with positive nickel patch test reactions should be told that toys may release nickel and be a potential chemical source in the manifestation of allergic contact dermatitis.

Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

NASA Astrophysics Data System (ADS)

Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges

The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.

A hip joint simulator study using new and physiologically scratched femoral heads with ultra-high molecular weight polyethylene acetabular cups.

PubMed

Barbour, P S; Stone, M H; Fisher, J

2000-01-01

This study validates a hip joint simulator configuration as compared with other machines and clinical wear rates using smooth metal and ceramic femoral heads and ultra-high molecular weight polyethylene (UHMWPE) acetabular cups. Secondly the wear rate of UHMWPE cups is measured in the simulator with deliberately scratched cobalt-chrome heads to represent the type of mild and severe scratch damage found on retrieved heads. Finally, the scratching processes are described and the resulting scratches compared with those found in retrieved cobalt-chrome heads. For smooth cobalt-chrome and zirconia heads the wear rates were found to be statistically similar to other simulator machines and within the normal range found from clinical studies. An increased wear rate was found with cobalt-chrome heads scratched using either the diamond stylus or the bead cobalt-chrome but the greatest increase was with the diamond scratched heads which generated scratches of similar dimensions to those on retrieved heads. A greater than twofold increase in wear rate is reported for these heads when compared with smooth heads. This increased wear rate is, however, still within the limits of data from clinical wear studies.

COBALT Flight Demonstrations Fuse Technologies

NASA Image and Video Library

2017-06-07

This 5-minute, 50-second video shows how the CoOperative Blending of Autonomous Landing Technologies (COBALT) system pairs new landing sensor technologies that promise to yield the highest precision navigation solution ever tested for NASA space landing applications. The technologies included a navigation doppler lidar (NDL), which provides ultra-precise velocity and line-of-sight range measurements, and the Lander Vision System (LVS), which provides terrain-relative navigation. Through flight campaigns conducted in March and April 2017 aboard Masten Space Systems' Xodiac, a rocket-powered vertical takeoff, vertical landing (VTVL) platform, the COBALT system was flight tested to collect sensor performance data for NDL and LVS and to check the integration and communication between COBALT and the rocket. The flight tests provided excellent performance data for both sensors, as well as valuable information on the integrated performance with the rocket that will be used for subsequent COBALT modifications prior to follow-on flight tests. Based at NASA’s Armstrong Flight Research Center in Edwards, CA, the Flight Opportunities program funds technology development flight tests on commercial suborbital space providers of which Masten is a vendor. The program has previously tested the LVS on the Masten rocket and validated the technology for the Mars 2020 rover.

Electrochemical Behaviour and Electrorefining of Cobalt in NaCl-KCl-K2TiF6 Melt

NASA Astrophysics Data System (ADS)

Kuznetsov, Sergey A.; Kazakova, Olga S.; Makarova, Olga V.

2009-08-01

The electrorefining of cobalt in NaCl-KCl-K2TiF6 (20 wt%) melt has been investigated. It was shown that complexes of Ti(III) and Co(II) appeared in the melt due to the reaction 2Ti(IV) + Co → 2Ti(III) + Co(II) and this reaction was entirely shifted to the right hand side. On the base of linear sweep voltammetry diagnostic criteria it was found that the discharge of Co(II) to Co metal is controlled by diffusion. The limiting current density of discharge Co(II) to metal in NaCl-KCl-K2TiF6 (20 wt%) melt was determined by steady-state voltammetry. The electrorefining of cobalt was carried out in hermetic electrolyser under argon atmosphere. Initial cathodic current density was changed from 0.2 Acm-2 up to 0.7 Acm-2, the electrolysis temperature varied within 973 - 1123 K. Behaviour of impurities during cobalt electrorefining was discussed. It was shown that electrorefining led to the elimination of most of the interstitial impurities (H2, N2, O2, C), with the result that the remaining impurity levels below 10 ppm impart high ductility to cobalt.

Facile synthesis of cobalt ferrite nanotubes using bacterial nanocellulose as template.

PubMed

Menchaca-Nal, S; Londoño-Calderón, C L; Cerrutti, P; Foresti, M L; Pampillo, L; Bilovol, V; Candal, R; Martínez-García, R

2016-02-10

A facile method for the preparation of cobalt ferrite nanotubes by use of bacterial cellulose nanoribbons as a template is described. The proposed method relays on a simple coprecipitation operation, which is a technique extensively used for the synthesis of nanoparticles (either isolated or as aggregates) but not for the synthesis of nanotubes. The precursors employed in the synthesis are chlorides, and the procedure is carried out at low temperature (90 °C). By the method proposed a homogeneous distribution of cobalt ferrite nanotubes with an average diameter of 217 nm in the bacterial nanocellulose (BC) aerogel (3%) was obtained. The obtained nanotubes are formed by 26-102 nm cobalt ferrite clusters of cobalt ferrite nanoparticles with diameters in the 9-13 nm interval. The nanoparticles that form the nanotubes showed to have a certain crystalline disorder, which could be attributed in a greater extent to the small crystallite size, and, in a lesser extent, to microstrains existing in the crystalline lattice. The BC-templated-CoFe2O4 nanotubes exhibited magnetic behavior at room temperature. The magnetic properties showed to be influenced by a fraction of nanoparticles in superparamagnetic state. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

DOE PAGES

Peters, Aaron W.; Li, Zhanyong; Farha, Omar K.; ...

2015-08-04

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 Co 9S 8. 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 themore » 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 CoS x reference material. Here, these results reveal AIM to be an effective method of incorporating high surface area and catalytically active cobalt sulfide in metal–organic frameworks.« less

Cobalt oxide-carbon nanosheet nanoarchitecture as an anode for high-performance lithium-ion battery.

PubMed

Wang, Huanlei; Mao, Nan; Shi, Jing; Wang, Qigang; Yu, Wenhua; Wang, Xin

2015-02-04

To improve the electrochemical performance of cobalt oxide owing to its inherent poor electrical conductivity and large volume expansion/contraction, Co3O4-carbon nanosheet hybrid nanoarchitectures were synthesized by a facile and scalable chemical process. However, it is still a challenge to control the size of Co3O4 particles down to ∼5 nm. Herein, we created nanosized cobalt oxide anchored 3D arrays of carbon nanosheets by the control of calcination condition. The uniformly dispersed Co3O4 nanocrystals on carbon nanosheets held a diameter down to ∼5 nm. When tested as anode materials for lithium-ion batteries, high lithium storage over 1200 mAh g(-1) is achieved, whereas high rate capability with capacity of about 390 mAh g(-1) at 10 A g(-1) is maintained through nanoscale diffusion distances and interconnected porous structure. After 500 cycles, the cobalt oxide-carbon nansheets hybrid display a reversible capacity of about 970 mAh g(-1) at 1 A g(-1). The synergistic effect between nanosized cobalt oxide and sheetlike interconnected carbon nanosheets lead to the greatly improved specific capacity and the initial Coulombic efficiency of the hybrids.

Controlling the Photocorrosion of Zinc Sulfide Nanoparticles in Water by Doping with Chloride and Cobalt Ions.

PubMed

Weide, Philipp; Schulz, Katharina; Kaluza, Stefan; Rohe, Markus; Beranek, Radim; Muhler, Martin

2016-12-06

Photodegradation under UV light irradiation is a major drawback in photocatalytic applications of sulfide semiconductors. ZnS nanoparticles were doped with very low amounts of chloride or cobalt ions in the ppm range and codoped with chloride and cobalt ions during their synthesis by precipitation in aqueous solution followed by calcination. The high-temperature wurtzite phase annealed at 800 °C had a high susceptibility to UV irradiation in water, while the low-temperature zincblende phase annealed at 400 °C was found to be stable. Chlorine doping increased the rate of photocorrosion in water, whereas cobalt doping led to a stabilization of the ZnS nanoparticles. Based on photochemical and spectroscopic investigations applying UV/vis, X-ray photoelectron, and photoluminescence spectroscopy, the increased susceptibility of Cl-doped ZnS is ascribed to a higher number of surface point defects, whereas the stabilization by Co 2+ is caused by additional recombination pathways for the charge carriers in the bulk, thus avoiding photocorrosion processes at the surface. Additional doping of Cl-doped ZnS with cobalt ions was found to counteract the detrimental effect of the chloride ions efficiently.

COBALT: A GN&C Payload for Testing ALHAT Capabilities in Closed-Loop Terrestrial Rocket Flights

NASA Technical Reports Server (NTRS)

Carson, John M., III; Amzajerdian, Farzin; Hines, Glenn D.; O'Neal, Travis V.; Robertson, Edward A.; Seubert, Carl; Trawny, Nikolas

2016-01-01

The COBALT (CoOperative Blending of Autonomous Landing Technology) payload is being developed within NASA as a risk reduction activity to mature, integrate and test ALHAT (Autonomous precision Landing and Hazard Avoidance Technology) systems targeted for infusion into near-term robotic and future human space flight missions. The initial COBALT payload instantiation is integrating the third-generation ALHAT Navigation Doppler Lidar (NDL) sensor, for ultra high-precision velocity plus range measurements, with the passive-optical Lander Vision System (LVS) that provides Terrain Relative Navigation (TRN) global-position estimates. The COBALT payload will be integrated onboard a rocket-propulsive terrestrial testbed and will provide precise navigation estimates and guidance planning during two flight test campaigns in 2017 (one open-loop and closed- loop). The NDL is targeting performance capabilities desired for future Mars and Moon Entry, Descent and Landing (EDL). The LVS is already baselined for TRN on the Mars 2020 robotic lander mission. The COBALT platform will provide NASA with a new risk-reduction capability to test integrated EDL Guidance, Navigation and Control (GN&C) components in closed-loop flight demonstrations prior to the actual mission EDL.

Energy levels scheme simulation of divalent cobalt doped bismuth germanate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreici, Emiliana-Laura, E-mail: andreicilaura@yahoo.com; Petkova, Petya; Avram, Nicolae M.

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 dopedmore » 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.« less

Studies of the Codeposition of Cobalt Hydroxide and Nickel Hydroxide

NASA Technical Reports Server (NTRS)

Ho, C. H.; Murthy, M.; VanZee, J. W.

1997-01-01

Topics considered include: chemistry, experimental measurements, planar film model development, impregnation model development, results and conclusion. Also included: effect of cobalt concentration on deposition/loading; effect of current density on loading distribution.

Cobalt-Bridged Ionic Liquid Polymer on a Carbon Nanotube for Enhanced Oxygen Evolution Reaction Activity.

PubMed

Ding, Yuxiao; Klyushin, Alexander; Huang, Xing; Jones, Travis; Teschner, Detre; Girgsdies, Frank; Rodenas, Tania; Schlögl, Robert; Heumann, Saskia

2018-03-19

By taking inspiration from the catalytic properties of single-site catalysts and the enhancement of performance through ionic liquids on metal catalysts, we exploited a scalable way to place single cobalt ions on a carbon-nanotube surface bridged by polymerized ionic liquid. Single dispersed cobalt ions coordinated by ionic liquid are used as heterogeneous catalysts for the oxygen evolution reaction (OER). Performance data reveals high activity and stable operation without chemical instability. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Recent Developments in Hydrogen Evolving Molecular Cobalt(II)-Polypyridyl Catalysts

PubMed Central

Queyriaux, N.; Jane, R. T.; Massin, J.; Artero, V.; Chavarot-Kerlidou, M.

2015-01-01

The search for efficient noble metal-free hydrogen-evolving catalysts is the subject of intense research activity. A new family of molecular cobalt(II)-polypyridyl catalysts has recently emerged. These catalysts prove more robust under reductive conditions than other cobalt-based systems and display high activities under fully aqueous conditions. This review discusses the design, characterization, and evaluation of these catalysts for electrocatalytic and light-driven hydrogen production. Mechanistic considerations are addressed and structure-catalytic activity relationships identified in order to guide the future design of more efficient catalytic systems. PMID:26688590

Low energy sputtering of cobalt by cesium ions

NASA Technical Reports Server (NTRS)

Handoo, A.; Ray, Pradosh K.

1989-01-01

An experimental facility to investigate low energy (less than 500 eV) sputtering of metal surfaces with ions produced by an ion gun is described. Results are reported on the sputtering yield of cobalt by cesium ions in the 100 to 500 eV energy range at a pressure of 1 times 10(exp -6) Torr. The target was electroplated on a copper substrate. The sputtered atoms were collected on a cobalt foil surrounding the target. Co-57 was used as a tracer to determine the sputtering yield.

Kinetics of Electrocatalysis of Dibromoalkyl Reductions Using Electrodes with Covalently Immobilized Metallotetraphenylporphyrins.

DTIC Science & Technology

1981-01-29

Technical Report Using Electrodes with Covalently Immobilized Metal l otetraphenyl porphyri ns G. PERFORMING ORG. REPORT NUMBER 7. AU𔄁IOR(’.) 0...and CH2BrCHBrCH 3 at the surfaces of electrodes to which cobalt(II) or copper (II) tetra(p-aminophenyl)porphyrin has been covalently attached is strongly...27514 ABSTRACT The reduction of PhCHBrCH 2 Br, PhCHBrCHBrPh, and CH2BrCHBrCH3 at the surfaces of electrodes to which cobalt(lI) or copper (If) tetra(p

A mechanistic study and computational prediction of iron, cobalt and manganese cyclopentadienone complexes for hydrogenation of carbon dioxide.

PubMed

Ge, Hongyu; Chen, Xiangyang; Yang, Xinzheng

2016-10-13

A series of cobalt and manganese cyclopentadienone complexes are proposed and examined computationally as promising catalysts for hydrogenation of CO 2 to formic acid with total free energies as low as 20.0 kcal mol -1 in aqueous solution. Density functional theory study of the newly designed cobalt and manganese complexes and experimentally reported iron cyclopentadienone complexes reveals a stepwise hydride transfer mechanism with a water or a methanol molecule assisted proton transfer for the cleavage of H 2 as the rate-determining step.

In-situ and Ex-situ Observations of Lithium De-intercalation from LiCoO2: Atomic Force Microscopy and Transmission Electron Microscopy Studies

DTIC Science & Technology

2005-06-01

has a layered structure consisting of lithium and cobalt sheets stacked alternatively between oxygen sheets. Li and Co occupy octahedral sites in...cobalt sheets stacked alternatively between ABCABC close-packed oxygen arrays. Li and Co occupy octahedral sites in alternating layers between the oxygen... Co 4.- o 4 Li Figure 1: Crystal structure of LiCoO2. LiCoO2 has a layered structure consisting of lithium and cobalt sheets stacked alternatively

MRFM (Magnetic Resonance Force Microscopy) MURI ARO Final Report (Grant W911NF-05-1-0403, University of Washington)

DTIC Science & Technology

2012-10-14

of high-gradient cobalt -tipped cantilevers, NanoMRI Conference 2012; Ascona, Switzerland; July 22 – 27, 2012, [url]. 4. R. Picone, J. Garbini, and J...url]. 5. J. G. Longenecker, H. J. Mamin, A. W. Senko, L. Chen, C. T. Rettner, D. Rugar, and J. A. Marohn, High gradient cobalt nanomagnets...Longenecker, H. J. Mamin, A. W. Senko, L. Chen, C. T. Rettner, D. Rugar, and J. A. Marohn, Development and characterization of high-gradient cobalt -tipped

The substitution of aluminum for cobalt in nanostructured bainitic steels

NASA Astrophysics Data System (ADS)

Yang, Jing; Qiu, Hui; Xu, Pudong; Yu, Hui; Wang, Yuchen

2018-06-01

Two kinds of new steels are designed, in which the only difference is the use of the alloy element aluminum instead of cobalt. The effect of cobalt and aluminum addition on the microstructure and mechanical properties of high-carbon nanostructured bainitic steels was studied. The microstructure and mechanical properties achieved by a low temperature au tempering treatment were investigated by optical microscopy, X-ray diffraction, scanning and transmission electron microscopy and hardness, tension, impact tests. The experimental results show that better mechanical properties were achieved in the high-carbon Al-contained steel.

Potassium bis(carbonato-O,O')(ethylenediamine-N,N')cobaltate(III) monohydrate at 173 K.

PubMed

Belai, N; Dickman, M H; Pope, M T

2001-07-01

The title salt, K[Co(C2H8N2)(CO3)2].H2O, consists of a distorted octahedral cobalt complex anion and a seven-coordinate potassium cation. Both metal atoms have crystallographic twofold symmetry, one C2 axis passing through the Co atom and C--C bond, and another along a short K--O (water) bond of 2.600 A (corrected for libration). The carbonate is bidentate to both cobalt and potassium and the water forms a hydrogen bond to a carbonate O atom.

The influence of various cooling rates during laser alloying on nodular iron surface layer

NASA Astrophysics Data System (ADS)

Paczkowska, Marta; Makuch, Natalia; Kulka, Michał

2018-06-01

The results of research referring to modification of the nodular iron surface layer by laser alloying with cobalt were presented. The aim of this study was to analyze the possibilities of cobalt implementation into the surface layer of nodular iron in various laser heat treatment conditions (by generating different cooling rates of melted surface layer). The modified surface layer of nodular iron was analyzed with OM, SEM, TEM, XRD, EDS and Vickers microhardness tester. The modified surface layer of nodular iron after laser alloying consisted of: the alloyed zone (melted with cobalt), the transition zone and the hardened zone from solid state. The alloyed zone was characterized by higher microstructure homogeneity - in contrast to the transition and the hardened zones. All the alloyed zones contained a dendritic microstructure. Dendrites consisted of martensite needles and retained austenite. Cementite was also detected. It was stated, that due to similar dimension of iron and cobalt atoms, their mutual replacement in the crystal lattice could occur. Thus, formation of phases based on α solution: Co-Fe (44-1433) could not be excluded. Although cobalt should be mostly diluted in solid solutions (because of its content in the alloyed zone), the other newly formed phases as Co (ε-hex.), FeC and cobalt carbides: Co3C, CoC0.25 could be present in the alloyed zones as a result of unique microstructure creation during laser treatment. Pearlite grains were observed in the zone, formed using lower power density of the laser beam and its longer exposition time. Simply, such conditions resulted in the cooling rate which was lower than critical cooling rate. The alloyed zones, produced at a higher cooling rate, were characterized by better microstructure homogeneity. Dendrites were finer in this case. This could result from a greater amount of crystal nuclei appearing at higher cooling rate. Simultaneously, the increased amount of γ-Fe and Fe3C precipitates was expected in the alloyed zone formed at higher cooling rates. The hardness of nodular iron surface layer, alloyed with cobalt, was up to 4-times higher than the hardness of core material. The hardness of alloyed zones strongly depended on laser treatment conditions. In the case of lower cooling rate, lower hardness was observed due to more coarse-grained microstructure and a presence of pearlite. The hardness of the alloyed zone increased (from 850 to 950HV0.1) together with the increasing cooling rate (from 2 · 103 to nearly 9 · 103 °C/s). Laser treatment enabled a formation of surface layers on nodular iron, alloyed with cobalt. The microstructure of such a surface layer could be controlled by the laser processing parameters. High hardness and fine microstructure of the laser-alloyed nodular iron with cobalt should result in higher resistance to wear, corrosion and even (due to effect of cobalt addition) elevated temperatures during operation conditions of machine parts.

Layered lithium manganese(0.4) nickel(0.4) cobalt(0.2) oxide(2) as cathode for lithium batteries

NASA Astrophysics Data System (ADS)

Ma, Miaomiao

The lithium ion battery occupies a dominant position in the portable battery market today. Intensive research has been carried out on every part of the battery to reduce cost, avoid environmental hazards, and improve battery performance. The commercial cathode material LiCoO2 has been partially replaced by LiNiyCo1- yO2 in the last two years, and mixed metal oxides have been introduced in the last quarter. From a resources point of view, only about 10 million tons of cobalt deposits are available from the world's minerals. However, there is about 500 times more manganese available than cobalt. Moreover, cobalt itself is not environmentally friendly. The purpose of this work is to find a promising alternative cathode material that can maintain good cycling performance, while at the same time reducing the cost and toxicity. When the cost is lowered, it is then possible to consider the larger scale use of lithium ion batteries in application such as hybrid electric vehicles (HEV). The research work presented in this thesis has focused on a specific composition of a layered lithium transition metal oxide, LiMn0.4Ni 0.4Co0.2O2 with the R3¯m structure. The presence of cobalt plays a critical role in minimizing transition metal migration to the lithium layer, and perhaps also in enhancing the electronic conductivity; however, cobalt is in limited supply and it is therefore more costly than nickel or manganese. The performance of LiMn0.4Ni0.4Co 0.2O2 was investigated and characterized utilizing various techniques an its performance compared with cobalt free LiMn0.5N i0.5O2, as well as with LiMn1/3Ni1/3Co 1/3O2, which is the most extensively studied replacement candidate for LiNiyCo1- yO2, and may be in SONY'S new hybrid cells. First, the structure and cation distribution in LiMn0.4Ni 0.4Co0.2O2 was studied by a combination of X-ray and neutron diffraction experiments. This combination study shows that about 3--5% nickel is present in the lithium layer, while manganese and cobalt are not observed in the lithium layer. In addition, the study did not reveal any ordering of the manganese, nickel, and cobalt, in the transition metal layer at room temperature. The structure changes during the first charge were also investigated both by ex situ and in situ X-ray diffractions. The same cell parameter trends are observed using both techniques. The hexagonal structure is maintained up to 4.6V, which is above the limit for normal cycling. Excess lithium addition reduces the cation disorder just as cobalt addition does. (Abstract shortened by UMI.)

A comparison of MRI and CT imaging clarity of titanium alloy and titanium alloy with cobalt-chromium-alloy pedicle screw and rod implants in the lumbar spine.

PubMed

Trammell, Terry R; Flint, Kathy; Ramsey, Curtis J

2012-08-15

Magnetic resonance imaging (MRI) and computed tomography (CT) imaging are important postoperative diagnostic and evaluation tools, particularly in patients who have undergone spinal fusions. Advancements in materials and imaging techniques have lessened artifact and improved overall imaging results. Systems that combine titanium alloy and cobalt-chromium components have been introduced to reduce implant profile while maintaining strength. The objective of this study was to determine if there were any differences in the clarity of imaging between two types of implant materials in a lumbar spine construct model. One of two lumbar spine stabilization implant systems, titanium alloy (titanium) or titanium alloy with cobalt-chromium alloy (titanium-cobalt), was placed to simulate a four-level fusion construct in two human cadaveric spine segments, followed by MRI and CT imaging. The implant systems were then removed from each cadaver and implanted in the other cadaver. Nine physician graders from three subspecialties scored the images using a 5-point scale, with higher imaging scores indicating greater clarity of the region of interest. Physician-rated scores were compared across systems and between physician groups. There were no significant differences in the overall mean total scores on the basis of construct material. Overall mean scores were 18.16 for titanium and 17.45 for titanium-cobalt (p = 0.275). Among images of the titanium-cobalt constructs, no significant differences in mean scores were found between specimens with use of MRI (p = 0.883) or with use of CT only (p = 0.274). Among images of the titanium system, a slightly significant difference was found between specimens with use of MRI (p = 0.044) but not with CT imaging (p = 0.837). Overall image clarity scores were not significantly different between titanium and titanium-cobalt implant systems in the lumbar spine. Observation of pertinent anatomy in the regions of interest was not degraded by the presence of either system.

Maintenance of stellite and tungsten carbide saw tips: respiratory health and exposure-response evaluations.

PubMed Central

Kennedy, S M; Chan-Yeung, M; Marion, S; Lea, J; Teschke, K

1995-01-01

OBJECTIVE--To study exposure to cobalt and chromium in saw maintenance rooms and test respiratory health among saw filers at lumber mills. Hard-metal lung disease is associated with cobalt in the manufacture of tungsten carbide tools; recently it has also been reported among tool maintenance workers. Lumber mills often use saws tipped with tungsten carbide or with a newer alloy, stellite (containing more cobalt, as well as chromium). METHODS--A cross sectional study of 118 saw filers at eight lumber mills was carried out that included a standardised questionnaire, spirometry, personal air sampling, and examination of tasks every 10 minutes (by observation). Comparison data were from a study of bus mechanics tested with similar methods. RESULTS AND CONCLUSION--Cobalt exposure was associated with tungsten carbide grinding but not with stellite grinding. Chromium exposure was associated mainly with stellite welding. Saw filers had a twofold increase in phlegm and wheeze (P < 0.01) and a threefold increase in cough, phlegm, and wheeze related to work (P < 0.001), but no increase in breathlessness. Stellite welding was associated with a significant increase in nasal symptoms and cough related to work and a small decrease in airflow (forced expiratory volume in one second/forced vital capacity (FEV1/FVC%), P < 0.05). Saw filers wet grinding with tungsten carbide had significant reductions in forced expiratory lung volumes (FEV1 and FVC, P < 0.05) and were significantly more likely to have FEV1 and FVC values in the abnormal range. Cobalt exposure (in wet grinding) and duration of work that involved tungsten carbide grinding were both associated with significant reductions in FEV1 and FVC. Average cobalt exposures in this study were about 5 micrograms/m3, well below the currently accepted permissible concentration, which suggests that the current workplace limit for cobalt may be too high. PMID:7735392

Partially oxidized atomic cobalt layers for carbon dioxide electroreduction to liquid fuel.

PubMed

Gao, Shan; Lin, Yue; Jiao, Xingchen; Sun, Yongfu; Luo, Qiquan; Zhang, Wenhua; Li, Dianqi; Yang, Jinlong; Xie, Yi

2016-01-07

Electroreduction of CO2 into useful fuels, especially if driven by renewable energy, represents a potentially 'clean' strategy for replacing fossil feedstocks and dealing with increasing CO2 emissions and their adverse effects on climate. The critical bottleneck lies in activating CO2 into the CO2(•-) radical anion or other intermediates that can be converted further, as the activation usually requires impractically high overpotentials. Recently, electrocatalysts based on oxide-derived metal nanostructures have been shown to enable CO2 reduction at low overpotentials. However, it remains unclear how the electrocatalytic activity of these metals is influenced by their native oxides, mainly because microstructural features such as interfaces and defects influence CO2 reduction activity yet are difficult to control. To evaluate the role of the two different catalytic sites, here we fabricate two kinds of four-atom-thick layers: pure cobalt metal, and co-existing domains of cobalt metal and cobalt oxide. Cobalt mainly produces formate (HCOO(-)) during CO2 electroreduction; we find that surface cobalt atoms of the atomically thin layers have higher intrinsic activity and selectivity towards formate production, at lower overpotentials, than do surface cobalt atoms on bulk samples. Partial oxidation of the atomic layers further increases their intrinsic activity, allowing us to realize stable current densities of about 10 milliamperes per square centimetre over 40 hours, with approximately 90 per cent formate selectivity at an overpotential of only 0.24 volts, which outperforms previously reported metal or metal oxide electrodes evaluated under comparable conditions. The correct morphology and oxidation state can thus transform a material from one considered nearly non-catalytic for the CO2 electroreduction reaction into an active catalyst. These findings point to new opportunities for manipulating and improving the CO2 electroreduction properties of metal systems, especially once the influence of both the atomic-scale structure and the presence of oxide are mechanistically better understood.

Generating a Metal-responsive Transcriptional Regulator to Test What Confers Metal Sensing in Cells*

PubMed Central

Osman, Deenah; Piergentili, Cecilia; Chen, Junjun; Chakrabarti, Buddhapriya; Foster, Andrew W.; Lurie-Luke, Elena; Huggins, Thomas G.; Robinson, Nigel J.

2015-01-01

FrmR from Salmonella enterica serovar typhimurium (a CsoR/RcnR-like transcriptional de-repressor) is shown to repress the frmRA operator-promoter, and repression is alleviated by formaldehyde but not manganese, iron, cobalt, nickel, copper, or Zn(II) within cells. In contrast, repression by a mutant FrmRE64H (which gains an RcnR metal ligand) is alleviated by cobalt and Zn(II). Unexpectedly, FrmR was found to already bind Co(II), Zn(II), and Cu(I), and moreover metals, as well as formaldehyde, trigger an allosteric response that weakens DNA affinity. However, the sensory metal sites of the cells' endogenous metal sensors (RcnR, ZntR, Zur, and CueR) are all tighter than FrmR for their cognate metals. Furthermore, the endogenous metal sensors are shown to out-compete FrmR. The metal-sensing FrmRE64H mutant has tighter metal affinities than FrmR by approximately 1 order of magnitude. Gain of cobalt sensing by FrmRE64H remains enigmatic because the cobalt affinity of FrmRE64H is substantially weaker than that of the endogenous cobalt sensor. Cobalt sensing requires glutathione, which may assist cobalt access, conferring a kinetic advantage. For Zn(II), the metal affinity of FrmRE64H approaches the metal affinities of cognate Zn(II) sensors. Counter-intuitively, the allosteric coupling free energy for Zn(II) is smaller in metal-sensing FrmRE64H compared with nonsensing FrmR. By determining the copies of FrmR and FrmRE64H tetramers per cell, then estimating promoter occupancy as a function of intracellular Zn(II) concentration, we show how a modest tightening of Zn(II) affinity, plus weakened DNA affinity of the apoprotein, conspires to make the relative properties of FrmRE64H (compared with ZntR and Zur) sufficient to sense Zn(II) inside cells. PMID:26109070

Synthesis of cobalt-containing mesoporous catalysts using the ultrasonic-assisted “pH-adjusting” method: Importance of cobalt species in styrene oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Baitao, E-mail: btli@scut.edu.cn; Zhu, Yanrun; Jin, Xiaojing

2015-01-15

Cobalt-containing SBA-15 and MCM-41 (Co-SBA-15 and Co-MCM-41) mesoporous catalysts were prepared via ultrasonic-assisted “pH-adjusting” technique in this study. Their physiochemical structures were comprehensively characterized and correlated with catalytic activity in oxidation of styrene. The nature of cobalt species depended on the type of mesoporous silica as well as pH values. The different catalytic performance between Co-SBA-15 and Co-MCM-41 catalysts originated from cobalt species. Cobalt species were homogenously incorporated into the siliceous framework of Co-SBA-15 in single-site Co(II) state, while Co{sub 3}O{sub 4} particles were loaded on Co-MCM-41 catalysts. The styrene oxidation tests showed that the single-site Co(II) state was moremore » beneficial to the catalytic oxidation of styrene. The higher styrene conversion and benzaldehyde selectivity over Co-SBA-15 catalysts were mainly attributed to single-site Co(II) state incorporated into the framework of SBA-15. The highest conversion of styrene (34.7%) with benzaldehyde selectivity of 88.2% was obtained over Co-SBA-15 catalyst prepared at pH of 7.5, at the mole ratio of 1:1 (styrene to H{sub 2}O{sub 2}) at 70 °C. - Graphical abstract: Cobalt-containing mesoporous silica catalysts were developed via ultrasonic-assisted “pH-adjusting” technique. Compared with Co{sub 3}O{sub 4} in Co-MCM-41, the single-site Co(II) state in Co-SBA-15 was more efficient for the styrene oxidation. - Highlights: • Fast and cost-effective ultrasonic technique for preparing mesoporous materials. • Incorporation of Co via ultrasonic irradiation and “pH-adjusting”. • Physicochemical comparison between Co-SBA-15 and Co-MCM-41. • Correlation of styrene oxidation activity and catalyst structural property.« less

Fine-Tuning the Activity of Metal–Organic Framework Supported Cobalt Catalysts for the Oxidative Dehydrogenation of Propane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhanyong; Peters, Aaron W.; Platero-Prats, Ana E.

Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal–organic framework (MOF) NU-1000, have previously been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (< 230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 via SIM (solvothermal deposition within MOFs–specifically the nodes) followed by incorporation of Co(II) ions via vapor-phase AIM (atomic layer deposition (ALD) in MOFs). This process yields a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters. Usingmore » difference envelope density (DED) analyses, the spatial locations of the promoter ions and catalytic cobalt ions are determined. For all samples the SIM-anchored promoter ions are sited between pairs of Zr 6 nodes along the MOF c-axis (channel-aligned axis) whereas the location of the AIM-anchored cobalt ions varies depending on the identity of promoter metal ion. With Ni(II)-, Al(III)-, or Ti(IV)-containing clusters as promoters, the oxy-cobalt species are sited atop the promoter sites; with Mo(VI) they grow exclusively on the MOF nodes sites (hexa-Zr(IV)- oxo,hydroxo,aqua units); with Zn(II) they grow on both the node and promoter. The NU-1000- supported bimetallic-oxide clusters are active for propane ODH after thermal activation under O 2 to open a cobalt coordination site and to oxidize Co(II) to Co(III), as evidenced by operando Xray absorption spectroscopy at the Co K-edge. The cobalt component is exclusively responsible for the observed catalysis. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the order: Mo(VI)« less

Fine-Tuning the Activity of Metal–Organic Framework Supported Cobalt Catalysts for the Oxidative Dehydrogenation of Propane

DOE PAGES

Li, Zhanyong; Peters, Aaron W.; Platero-Prats, Ana E.; ...

2017-10-04

Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal–organic framework (MOF) NU-1000, have previously been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (< 230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 via SIM (solvothermal deposition within MOFs–specifically the nodes) followed by incorporation of Co(II) ions via vapor-phase AIM (atomic layer deposition (ALD) in MOFs). This process yields a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters. Usingmore » difference envelope density (DED) analyses, the spatial locations of the promoter ions and catalytic cobalt ions are determined. For all samples the SIM-anchored promoter ions are sited between pairs of Zr 6 nodes along the MOF c-axis (channel-aligned axis) whereas the location of the AIM-anchored cobalt ions varies depending on the identity of promoter metal ion. With Ni(II)-, Al(III)-, or Ti(IV)-containing clusters as promoters, the oxy-cobalt species are sited atop the promoter sites; with Mo(VI) they grow exclusively on the MOF nodes sites (hexa-Zr(IV)- oxo,hydroxo,aqua units); with Zn(II) they grow on both the node and promoter. The NU-1000- supported bimetallic-oxide clusters are active for propane ODH after thermal activation under O 2 to open a cobalt coordination site and to oxidize Co(II) to Co(III), as evidenced by operando Xray absorption spectroscopy at the Co K-edge. The cobalt component is exclusively responsible for the observed catalysis. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the order: Mo(VI)« less

Mixed-Valent Dicobalt and Iron-Cobalt Complexes with High-Spin Configurations and Short Metal-Metal Bonds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zall, Christopher M.; Clouston, Laura J.; Young, Jr., Victor G.

2013-09-23

Cobalt–cobalt and iron–cobalt bonds are investigated in coordination complexes with formally mixed-valent [M 2] 3+ cores. The trigonal dicobalt tris(diphenylformamidinate) compound, Co 2(DPhF) 3, which was previously reported by Cotton, Murillo, and co-workers (Inorg. Chim. Acta 1996, 249, 9), is shown to have an energetically isolated, high-spin sextet ground-state by magnetic susceptibility and electron paramagnetic resonance (EPR) spectroscopy. A new tris(amidinato)amine ligand platform is introduced. By tethering three amidinate donors to an apical amine, this platform offers two distinct metal-binding sites. Using the phenyl-substituted variant (abbreviated as L Ph), the isolation of a dicobalt homobimetallic and an iron–cobalt heterobimetallic aremore » demonstrated. The new [Co 2] 3+ and [FeCo] 3+ cores have high-spin sextet and septet ground states, respectively. Their solid-state structures reveal short metal–metal bond distances of 2.29 Å for Co–Co and 2.18 Å for Fe–Co; the latter is the shortest distance for an iron–cobalt bond to date. To assign the positions of iron and cobalt atoms as well as to determine if Fe/Co mixing is occurring, X-ray anomalous scattering experiments were performed, spanning the Fe and Co absorption energies. These studies show only a minor amount of metal-site mixing in this complex, and that FeCoL Ph is more precisely described as (Fe 0.94(1)Co 0.06(1))(Co 0.95(1)Fe 0.05(1))L Ph. The iron–cobalt heterobimetallic has been further characterized by Mössbauer spectroscopy. Its isomer shift of 0.65 mm/s and quadrupole splitting of 0.64 mm/s are comparable to the related diiron complex, Fe 2(DPhF) 3. On the basis of spectroscopic data and theoretical calculations, it is proposed that the formal [M 2] 3+ cores are fully delocalized.« less

Iron- and cobalt-catalyzed arylation of azetidines, pyrrolidines, and piperidines with Grignard reagents.

PubMed

Barré, Baptiste; Gonnard, Laurine; Campagne, Rémy; Reymond, Sébastien; Marin, Julien; Ciapetti, Paola; Brellier, Marie; Guérinot, Amandine; Cossy, Janine

2014-12-05

Iron- and cobalt-catalyzed cross-couplings between iodo-azetidines, -pyrrolidines, -piperidines, and Grignard reagents are disclosed. The reaction is efficient, cheap, chemoselective and tolerates a large variety of (hetero)aryl Grignard reagents.

Minimum five-year follow-up wear measurement of longevity highly cross-linked polyethylene cup against cobalt-chromium or zirconia heads.

PubMed

Nakahara, Ichiro; Nakamura, Nobuo; Nishii, Takashi; Miki, Hidenobu; Sakai, Takashi; Sugano, Nobuhiko

2010-12-01

We investigated the efficacy of combining highly cross-linked polyethylene with ceramic heads on further reduction in polyethylene wear compared with the combination with cobalt-chromium heads via PolyWare computer-assisted method. A prospective cohort study was performed on 102 cementless total hip arthroplasties using Longevity (Zimmer, Warsaw, Ind) highly cross-linked polyethylene liners. Either 26-mm zirconia heads or 26-mm cobalt-chromium heads were randomly used in 51 hips each. At a mean follow-up of 6.7 years, no significant differences were identified between the groups for total penetration rate and steady-state wear rate. Osteolysis was not observed in any hips in either group. In conclusion, no advantage was seen for the 26-mm zirconia head compared with the 26-mm cobalt-chromium head in this period. Copyright © 2010 Elsevier Inc. All rights reserved.

Stabilized CdSe-CoPi composite photoanode for light-assisted water oxidation by transformation of a CdSe/cobalt metal thin film.

PubMed

Costi, Ronny; Young, Elizabeth R; Bulović, Vladimir; Nocera, Daniel G

2013-04-10

Integration of water splitting catalysts with visible-light-absorbing semiconductors would enable direct solar-energy-to-fuel conversion schemes such as those based on water splitting. A disadvantage of some common semiconductors that possess desirable optical bandgaps is their chemical instability under the conditions needed for oxygen evolution reaction (OER). In this study, we demonstrate the dual benefits gained from using a cobalt metal thin-film as the precursor for the preparation of cobalt-phosphate (CoPi) OER catalyst on cadmium chalcogenide photoanodes. The cobalt layer protects the underlying semiconductor from oxidation and degradation while forming the catalyst and simultaneously facilitates the advantageous incorporation of the cadmium chalcogenide layer into the CoPi layer during continued processing of the electrode. The resulting hybrid material forms a stable photoactive anode for light-assisted water splitting.

Complex magnetic differentiation of cobalts in Na x CoO2 with 22 K Néel temperature

NASA Astrophysics Data System (ADS)

Mukhamedshin, I. R.; Gilmutdinov, I. F.; Salosin, M. A.; Alloul, H.

2014-06-01

Single crystals of sodium cobaltates Na x CoO2 with x ≈ 0.8 were grown by the floating zone technique. Using electrochemical Na de-intercalation method we reduced the sodium content in the as-grown crystals down to pure phase with 22 K Néel temperature and x ≈ 0.77. The 59Co NMR study in the paramagnetic state of the T N = 22 K phase permitted us to evidence that at least 6 Co sites are differentiated. They could be separated by their magnetic behavior into three types: a single site with cobalt close to non-magnetic Co3+, two sites with the most magnetic cobalts in the system, and the remaining three sites displaying an intermediate behavior. This unusual magnetic differentiation calls for more detailed NMR experiments on our well characterized samples.

The use of Co2+ for crystallization and structure determination, using a conventional mono­chromatic X-ray source, of flax rust avirulence protein

PubMed Central

Gunčar, Gregor; Wang, Ching-I A.; Forwood, Jade K.; Teh, Trazel; Catanzariti, Ann-Maree; Ellis, Jeffrey G.; Dodds, Peter N.; Kobe, Boštjan

2007-01-01

Metal-binding sites are ubiquitous in proteins and can be readily utilized for phasing. It is shown that a protein crystal structure can be solved using single-wavelength anomalous diffraction based on the anomalous signal of a cobalt ion measured on a conventional monochromatic X-ray source. The unique absorption edge of cobalt (1.61 Å) is compatible with the Cu Kα wavelength (1.54 Å) commonly available in macromolecular crystallography laboratories. This approach was applied to the determination of the structure of Melampsora lini avirulence protein AvrL567-A, a protein with a novel fold from the fungal pathogen flax rust that induces plant disease resistance in flax plants. This approach using cobalt ions may be applicable to all cobalt-binding proteins and may be advantageous when synchrotron radiation is not readily available. PMID:17329816

Tungsten-nickel-cobalt alloy and method of producing same

DOEpatents

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.

Nickel cobalt phosphorous low stress electroplating

NASA Technical Reports Server (NTRS)

Engelhaupt, Darell E. (Inventor); Ramsey, Brian D. (Inventor)

2002-01-01

An electrolytic plating process is provided for electrodepositing a nickel or nickel cobalt alloy which contains at least about 2% to 25% by atomic volume of phosphorous. The process solutions contains nickel and optionally cobalt sulfate, hypophosphorous acid or a salt thereof, boric acid or a salt thereof, a monodentate organic acid or a salt thereof, and a multidentate organic acid or a salt thereof. The pH of the plating bath is from about 3.0 to about 4.5. An electroplating process is also provided which includes electroplating from the bath a nickel or nickel cobalt phosphorous alloy. This process can achieve a deposit with high microyield of at least about 84 kg/mm.sup.2 (120 ksi) and a density lower than pure nickel of about 8.0 gm/cc. This process can be used to plate a deposit of essentially zero stress at plating temperatures from ambient to 70.degree. C.

Stacking faults density driven collapse of magnetic energy in hcp-cobalt nano-magnets

NASA Astrophysics Data System (ADS)

Nong, H. T. T.; Mrad, K.; Schoenstein, F.; Piquemal, J.-Y.; Jouini, N.; Leridon, B.; Mercone, S.

2017-06-01

Cobalt nanowires with different shape parameters were synthesized via the polyol process. By calculating the magnetic energy product (BH max) both for dried nano-powder and for nanowires in their synthesis solution, we observed unexpected independent BH max values from the nanowires shape. A good alignment of the nanowires leads to a higher BH max value. Our results show that the key parameter driving the magnetic energy product of the cobalt nanowires is the stacking fault density. An exponential collapse of the magnetic energy is observed at very low percentage of structural faults. Cobalt nanowires with almost perfect hcp crystalline structures should present high magnetic energy, which is promising for application in rare earth-free permanent magnets. Oral talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

Photocatalysts Based on Cobalt-Chelating Conjugated Polymers for Hydrogen Evolution from Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Lianwei; Hadt, Ryan G.; Yao, Shiyu

Developing photocatalytic systems for water splitting to generate oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this work, we report the first example of heterogeneous photocatalysts for hydrogen evolution based on in-chain cobalt-chelating conjugated polymers. Four conjugated polymers chelated with earth abundant cobalt ions were synthesized and found to evolve hydrogen photocatalytically from water. These polymers are designed to combine functions of the conjugated backbone as light-harvesting antenna and electron transfer conduit with the in-chain bipyridyl chelated transition metal centers as catalytic active sites. In addition, these polymers are soluble in organic solvents,more » enabling effective interactions with the substrates as well as detailed characterization. We also found a polymer-dependent optimal cobalt chelating concentration at which the highest photocatalytic hydrogen production (PHP) activity can be achieved.« less

Reload of an industrial cylindrical cobalt source rack

NASA Astrophysics Data System (ADS)

Gharbi, F.; Kadri, O.; Trabelsi, A.

2006-10-01

This work presents a Monte Carlo study of the cylindrical cobalt source rack geometry of the Tunisian gamma irradiation facility, using the GEANT code developed at CERN. The study investigates the question of the reload of the source rack. The studied configurations consist in housing four new cobalt pencils, two in the upper and two in the lower cylinder of the source rack. Global dose rate uniformity inside a "dummy" product for the case of routine and nonroutine irradiation, and as function of the product bulk density, was calculated for eight hypothetical configurations. The same calculation was also performed for both of the original and the ideal (but not practical) configurations. It was shown that hypothetical cases produced dose uniformity variations, according to product density, that were statistically no different than the original and the ideal configurations and that the reload procedure cannot improve the irradiation quality inside the facilities using cylindrical cobalt source racks.

The copper-cobalt deposits of the Quartzburg district, Grant County, Oregon

USGS Publications Warehouse

Vhay, John Stewart

1960-01-01

The copper- and cobalt-bearing veins of part of the Quartzburg district are in fracture zones trending about N. 70 degrees E. in folded Permian (?) metavolcanic rocks on the southwest side of a quartz diorite stock. Along many of the veins fine-grained tourmaline and quartz have replaced the country rock. The primary ore minerals are chalcopyrite, glaucodot, safflorite, and cobaltite. The copper- and cobalt-rich parts of the deposits appear to be in separate ore shoots. Gold content is generally higher in the cobalt-bearing parts of the veins than in the copper-rich parts. The Standard mine has developed part of one vein zone. Several other vein zones that crop out may contain as much copper as the Standard vein zone. Further bulldozing and diamond drilling on the surface, and more geologic mapping, sampling, and diamond drilling underground are suggested as means to explore for more ore deposits.

Synthesis, Crystal Structure, and Magnetic Properties of the Linear-Chain Cobalt Oxide Sr 5Pb 3CoO 12

NASA Astrophysics Data System (ADS)

Yamaura, K.; Huang, Q.; Takayama-Muromachi, E.

2002-02-01

The novel spin-chain cobalt oxide Sr5Pb3CoO12 [Poverline6×2m, a=10.1093(2) Å and c=3.562 51(9) Å at 295 K] is reported. A polycrystalline sample of the compound was studied by neutron diffraction (at 6 and 295 K) and magnetic susceptibility measurements (5 to 390 K). The cobalt oxide was found to be analogous to the copper oxide Sr5Pb3CuO12, which is comprised of magnetic-linear chains at an interchain distance of 10 Å. Although the cobalt oxide chains (μeff of 3.64 μB per Co) are substantially antiferromagnetic (θW=-38.8 K), neither low-dimensional magnetism nor long-range ordering has been found; a local-structure disorder in the chains might have an impact on the magnetism. This compound is highly electrically insulating.

Controlled cobalt doping in biogenic magnetite nanoparticles

PubMed Central

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

Biocorrosion study of titanium-cobalt alloys.

PubMed

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.

Growth of single-crystalline cobalt silicide nanowires and their field emission property

PubMed Central

2013-01-01

In this work, cobalt silicide nanowires were synthesized by chemical vapor deposition processes on Si (100) substrates with anhydrous cobalt chloride (CoCl2) as precursors. Processing parameters, including the temperature of Si (100) substrates, the gas flow rate, and the pressure of reactions were varied and studied; additionally, the physical properties of the cobalt silicide nanowires were measured. It was found that single-crystal CoSi nanowires were grown at 850°C ~ 880°C and at a lower gas flow rate, while single-crystal Co2Si nanowires were grown at 880°C ~ 900°C. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with field emission measurements demonstrates that CoSi nanowires are attractive choices for future applications in field emitters. PMID:23819795

Synthesis of cobalt stearate as oxidant additive for oxo-biodegradable polyethylene

NASA Astrophysics Data System (ADS)

Asriza, Ristika O.; Arcana, I. Made

2015-09-01

Cobalt stearate is an oxidant additives that can initiate a process of degradation in high density polyethylene (HDPE). To determine the effect of cobalt stearate in HDPE, oxo-biodegradable polyethylene film was given an irradiation with UV light or heating at various temperature. After given a heating, the FTIR spectra showed a new absorption peak at wave number 1712 cm-1 indicating the presence of carbonyl groups in polymers, whereas after irradiation with UV light is not visible the presence of this absorption peak. The increase concentration of cobalt stearate added in HDPE and the higher heating temperature, the intensity of the absorption peak of the carbonyl group increased. The increasing intensity of the carbonyl group absorption is caused the presence of damage in the film surface after heating, and this result is supported by analysis the surface properties of the film with using SEM. Biodegradation tests were performed on oxo-biodegradable polyethylene film which has been given heating or UV light with using activated sludge under optimal conditions the growth of microorganisms. After biodegradation, the maximum weight decreased by 23% in the oxo-biodegradable polyethylene film with a cobalt stearate concentration of 0.2% and after heating at a temperature of 75 °C for 10 days, and only 0.69% in the same film after irradiation UV light for 10 days. Based on the results above, cobalt stearate additive is more effective to initiate the oxidative degradation of HDPE when it is initiated by heating compared to irradiation with UV light.

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content.

PubMed

Clark, R G; Ellison, R S; Mortleman, L; Kirk, J A; Henderson, H V

1999-08-01

To obtain information on serum and liver vitamin B12 and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B12 in young dairy cattle when grazing pasture of low cobalt content. Methodology. Forty dairy cattle (12 Friesian, 14 Friesian x Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for vitamin B12 concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations. No weight gain response occurred vitamin B12 supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver vitamin B12 concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B12 concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation. Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum vitamin B12 concentrations at which growth responses to vitamin B12 or cobalt supplementation are likely under New Zealand pastoral grazing conditions.

Geodynamic and climate controls in the formation of Mio-Pliocene world-class oxidized cobalt and manganese ores in the Katanga province, DR Congo

NASA Astrophysics Data System (ADS)

Decrée, Sophie; Deloule, Étienne; Ruffet, Gilles; Dewaele, Stijn; Mees, Florias; Marignac, Christian; Yans, Johan; de Putter, Thierry

2010-10-01

The Katanga province, Democratic Republic of Congo, hosts world-class cobalt deposits accounting for ~50% of the world reserves. They originated from sediment-hosted stratiform copper and cobalt sulfide deposits within Neoproterozoic metasedimentary rocks. Heterogenite, the main oxidized cobalt mineral, is concentrated as “cobalt caps” along the top of silicified dolomite inselbergs. The supergene cobalt enrichment process is part of a regional process of residual ore formation that also forms world-class “manganese cap” deposits in western Katanga, i.e., the “black earths” that are exploited by both industrial and artisanal mining. Here, we provide constraints on the genesis and the timing of these deposits. Ar-Ar analyses of oxidized Mn ore and in situ U-Pb SIMS measurements of heterogenite yield Mio-Pliocene ages. The Ar-Ar ages suggest a multi-phase process, starting in the Late Miocene (10-5 Ma), when the metal-rich substratum was exposed to the action of meteoric fluids, due to major regional uplift. Further oxidation took place in the Pliocene (3.7-2.3 Ma) and formed most of the observed deposits under humid conditions: Co- and Mn-caps on metal-rich substrata, and coeval Fe laterites on barren areas. These deposits formed prior to the regional shift toward more arid conditions in Central Africa. Arid conditions still prevailed during the Quaternary and resulted in erosion and valley incision, which dismantled the metal-bearing caps and led to ore accumulation in valleys and along foot slopes.

Effect of Cobalt on Sperm Motility in an Endangered Trout Species, Salmo coruhensis.

PubMed

Kocabaş, Mehmet; Kutluyer, Filiz

2017-12-01

Experiments were designed to examine the in vitro effect of cobalt on sperm motility of the endangered trout species (Salmo coruhensis). Sperm samples were diluted in an immobilizing solution, and activated in a motility-activation solution that was supplemented with cobalt at concentrations of 1, 10, 100 and 1000 mg/L. The percentage of motile sperm and duration of motility were determined. Cobalt concentrations of 1-100 mg/L had a positive effect on the percentage of motile sperm and duration of motility compared to the control group, while a concentration of 1000 mg/L resulted in decreases in these parameters (p < 0.05). The percentages of motile sperm at cobalt concentrations of 0, 1, 10, 100 and 1000 mg/L were 83.33% ± 0.25%, 88.33% ± 0.34%, 89.00% ± 0.57%, 90.00% ± 0.87% and 42.50% ± 0.45%, respectively; and the time durations over which the sperm remained motile were 72.00 ± 0.63, 74.83 ± 0.28, 77.40 ± 0.47, 81.14 ± 0.78, and 50.25 ± 0.67 s, respectively. This study has shown that sperm motility and duration were significantly enhanced (p < 0.05) at cobalt concentrations of 1, 10 and 100 mg/L, relative to controls, and significantly decreased at 1000 mg/L.

Synthesis of cobalt stearate as oxidant additive for oxo-biodegradable polyethylene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asriza, Ristika O.; Arcana, I Made, E-mail: arcana@chem.itb.ac.id

Cobalt stearate is an oxidant additives that can initiate a process of degradation in high density polyethylene (HDPE). To determine the effect of cobalt stearate in HDPE, oxo-biodegradable polyethylene film was given an irradiation with UV light or heating at various temperature. After given a heating, the FTIR spectra showed a new absorption peak at wave number 1712 cm{sup −1} indicating the presence of carbonyl groups in polymers, whereas after irradiation with UV light is not visible the presence of this absorption peak. The increase concentration of cobalt stearate added in HDPE and the higher heating temperature, the intensity of themore » absorption peak of the carbonyl group increased. The increasing intensity of the carbonyl group absorption is caused the presence of damage in the film surface after heating, and this result is supported by analysis the surface properties of the film with using SEM. Biodegradation tests were performed on oxo-biodegradable polyethylene film which has been given heating or UV light with using activated sludge under optimal conditions the growth of microorganisms. After biodegradation, the maximum weight decreased by 23% in the oxo-biodegradable polyethylene film with a cobalt stearate concentration of 0.2% and after heating at a temperature of 75 °C for 10 days, and only 0.69% in the same film after irradiation UV light for 10 days. Based on the results above, cobalt stearate additive is more effective to initiate the oxidative degradation of HDPE when it is initiated by heating compared to irradiation with UV light.« less

Comparison of effects of overload on parameters and performance of samarium-cobalt and strontium-ferrite radially oriented permanent magnet brushless DC motors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demerdash, N.A.; Nehl, T.W.; Nyamusa, T.A.

1985-08-01

Effects of high momentary overloads on the samarium-cobalt and strontium-ferrite permanent magnets and the magnetic field in electronically commutated brushless dc machines, as well as their impact on the associated machine parameters were studied. The effect of overload on the machine parameters, and subsequently on the machine system performance was also investigated. This was accomplished through the combined use of finite element analysis of the magnetic field in such machines, perturbation of the magnetic energies to determine machine inductances, and dynamic simulation of the performance of brushless dc machines, when energized from voltage source inverters. These effects were investigated throughmore » application of the above methods to two equivalent 15 hp brushless dc motors, one of which was built with samarium-cobalt magnets, while the other was built with strontium- ferrite magnets. For momentary overloads as high as 4.5 p.u. magnet flux reductions of 29% and 42% of the no load flux were obtained in the samarium-cobalt and strontiumferrite machines, respectively. Corresponding reductions in the line to line armature inductances of 52% and 46% of the no load values were reported for the samarium-cobalt and strontium-ferrite cases, respectively. The overload affected the profiles and magnitudes of armature induced back emfs. Subsequently, the effects of overload on machine parameters were found to have significant impact on the performance of the machine systems, where findings indicate that the samarium-cobalt unit is more suited for higher overload duties than the strontium-ferrite machine.« less

An outbreak of occupational asthma due to chromium and cobalt.

PubMed

Walters, G I; Moore, V C; Robertson, A S; Burge, C B S G; Vellore, A-D; Burge, P S

2012-10-01

Five metal turners employed by an aerospace manufacturer presented to the Birmingham Chest Clinic occupational lung disease unit. Four cases of occupational asthma (OA) due to chromium salt (3) and cobalt (1) were diagnosed by serial peak-expiratory flow measurements and specific inhalation challenge testing. To measure the extent of the outbreak and to provide epidemiological data to ascertain the aetiology. Participants answered a detailed, self-administered questionnaire, designed to detect occupational lung disease. Urine chromium and cobalt excretion, spirometry and exhaled nitric oxide measurements were taken. Those with possible, probable or definite non-OA or OA, after questionnaire, were invited to undertake two-hourly peak flow measurements and received specialist follow-up. A total of 62 workers (95% of workforce) participated. Sixty-one per cent of employees were working in higher metalworking fluid (MWF) exposure areas. Ninety per cent of workers had urinary chromium excretion indicating occupational exposure. Sixty-six per cent of workers reported active respiratory symptoms, although there were no significant differences between exposure groups. Two further workers with probable OA were identified and had significantly higher urinary chromium and cobalt concentration than asymptomatic controls. Eighteen cases of occupational rhinitis (OR) were identified, with significantly raised urinary chromium concentration compared with asymptomatic controls. Chromium salt and cobalt can be responsible for OA and OR in workers exposed to MWF aerosols. Onset of symptoms in those with positive specific challenges followed change in MWF brand. Workers with OA had increased urinary concentrations of chromium and cobalt, and those with OR had increased urinary concentrations of chromium.

Localized comedo formation after cobalt irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myskowski, P.L.; Safai, B.

1981-10-01

Following Cobalt-60 irradiation for a left frontotemporal tumor, a 61-year-old woman developed comedones on the forehead. These changes responded to conventional acne therapy with retinoic acid. Multiple acneigenic factors were implicated in the pathogenesis of her lesions.

Ammonia induced precipitation of cobalt hydroxide: observation of turbostratic disorder

NASA Astrophysics Data System (ADS)

Ramesh, T. N.; Rajamathi, Michael; Kamath, P. Vishnu

2003-05-01

Cobalt hydroxide freshly precipitated from aqueous solutions of Co salts using ammonia, is a layered phase having a 9.17 Å interlayer spacing. DIFFaX simulations of the PXRD pattern reveal that it is turbostratically disordered.

21 CFR 888.3390 - Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis.

Code of Federal Regulations, 2014 CFR

2014-04-01

... includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a snap-fit acetabular component made of an alloy, such as cobalt-chromium-molybdenum, and ultra-high...

21 CFR 888.3390 - Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis.

Code of Federal Regulations, 2013 CFR

2013-04-01

... includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a snap-fit acetabular component made of an alloy, such as cobalt-chromium-molybdenum, and ultra-high...

21 CFR 888.3390 - Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis.

Code of Federal Regulations, 2011 CFR

2011-04-01

... includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a snap-fit acetabular component made of an alloy, such as cobalt-chromium-molybdenum, and ultra-high...

PLUTONIUM-CERIUM-COBALT AND PLUTONIUM-CERIUM-NICKEL ALLOYS

DOEpatents

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.

Non-aqueous primary cell

NASA Astrophysics Data System (ADS)

James, S. D.; Smith, P. H.; Oneill, K. M.; Wilson, M. H.

1986-05-01

This patent application relates to electrochemical cells and especially to high-energy, liquid cathode, non-aqueous lithium electrochemical cells free from highly toxic materials. A non-aqueous lithium electrochemical cell is described which includes a halocarbon cathode depolarizer which is 1,2-dichloroethane, 1.1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,2-dichloro-1,1-difluoroethane or mixtures thereof and a cathode catalyst which is copper, rhodium, palladium, cobalt phthalocyanine, nickel phthalocyanine, iron phthalocyanine, a cobalt tetraaza-(14)-annulene, a nickel tetraaza-(14)-annulene, a iron tetraaza-(14)-annulene, a cobalt porphyrin, a nickel porphyrin, a iron porphyrin, or a mixture thereof.

Procedure for rapid determination of nickel, cobalt, and chromium in airborne particulate samples

NASA Technical Reports Server (NTRS)

Davis, W. F.; Graab, J. W.

1972-01-01

A rapid, selective procedure for the determination of 1 to 20 micrograms of nickel, chromium, and cobalt in airborne particulates is described. The method utilizes the combined techniques of low temperature ashing and atomic absorption spectroscopy. The airborne particulates are collected on analytical filter paper. The filter papers are ashed, and the residues are dissolved in hydrochloric acid. Nickel, chromium, and cobalt are determined directly with good precision and accuracy by means of atomic absorption. The effects of flame type, burner height, slit width, and lamp current on the atomic absorption measurements are reported.

Isolation of genomic DNA using magnetic cobalt ferrite and silica particles.

PubMed

Prodelalová, Jana; Rittich, Bohuslav; Spanová, Alena; Petrová, Katerina; Benes, Milan J

2004-11-12

Adsorption separation techniques as an alternative to laborious traditional methods (e.g., based on phenol extraction procedure) have been applied for DNA purification. In this work we used two types of particles: silica and cobalt ferrite (unmodified or modified with a reagent containing weakly basic aminoethyl groups, aminophenyl groups, or alginic acid). DNA from chicken erythrocytes and DNA isolated from bacteria Lactococcus lactis were used for testing of adsorption/desorption properties of particles. The cobalt ferrite particles modified with different reagents were used for isolation of PCR-ready bacterial DNA from different dairy products.

Assessment of wrought ASTM F1058 cobalt alloy properties for permanent surgical implants.

PubMed

Clerc, C O; Jedwab, M R; Mayer, D W; Thompson, P J; Stinson, J S

1997-01-01

The behavior of the ASTM F1058 wrought cobalt-chromium-nickel-molybdenum-iron alloy (commonly referred to as Elgiloy or Phynox) is evaluated in terms of mechanical properties, magnetic resonance imaging, corrosion resistance, and biocompatibility. The data found in the literature, the experimental corrosion and biocompatibility results presented in this article, and its long track record as an implant material demonstrate that the cobalt superalloy is an appropriate material for permanent surgical implants that require high yield strength and fatigue resistance combined with high elastic modulus, and that it can be safely imaged with magnetic resonance.

Synthesis and characterization of graphene quantum dots/cobalt ferrite nanocomposite

NASA Astrophysics Data System (ADS)

Ramachandran, Shilpa; Sathishkumar, M.; Kothurkar, Nikhil K.; Senthilkumar, R.

2018-02-01

A facile method has been developed for the synthesis of a graphene quantum dots/cobalt ferrite nanocomposite. Graphene quantum dots (GQDs) were synthesized by a simple bottom-up method using citric acid, followed by the co-precipitation of cobalt ferrite nanoparticles on the graphene quantum dots. The morphology, structural analysis, optical properties, magnetic properties were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectroscopy, fluorescence spectroscopy, vibrating sample magnetometry (VSM) measurements. The synthesized nanocomposite showed good fluorescence and superparamagnetic properties, which are important for biomedical applications.

Sputtering of cobalt and chromium by argon and xenon ions near the threshold energy region

NASA Technical Reports Server (NTRS)

Handoo, A. K.; Ray, P. K.

1993-01-01

Sputtering yields of cobalt and chromium by argon and xenon ions with energies below 50 eV are reported. The targets were electroplated on copper substrates. Measurable sputtering yields were obtained from cobalt with ion energies as low as 10 eV. The ion beams were produced by an ion gun. A radioactive tracer technique was used for the quantitative measurement of the sputtering yield. Co-57 and Cr-51 were used as tracers. The yield-energy curves are observed to be concave, which brings into question the practice of finding threshold energies by linear extrapolation.

Room temperature ferromagnetic and semiconducting properties of graphene adsorbed with cobalt oxide using electrochemical method

NASA Astrophysics Data System (ADS)

Park, Chang-Soo; Lee, Kyung Su; Chu, Dongil; Lee, Juwon; Shon, Yoon; Kim, Eun Kyu

2017-12-01

We report the room temperature ferromagnetic properties of graphene adsorbed by cobalt oxide using electrochemical method. The cobalt oxide doping onto graphene was carried out in 0.1 M LiCoO2/DI-water solution. The doped graphene thin film was determined to be a single layer from Raman analysis. The CoO doped graphene has a clear ferromagnetic hysteresis at room temperature and showed a remnant magnetization, 128.2 emu/cm3. The temperature dependent conductivity of the adsorbed graphene showed the semiconducting behavior and a band gap opening of 0.12 eV.

Investigation of atypical molten pool dynamics in tungsten carbide-cobalt during laser deposition using in-situ thermal imaging

NASA Astrophysics Data System (ADS)

Xiong, Yuhong; Hofmeister, William H.; Smugeresky, John E.; Delplanque, Jean-Pierre; Schoenung, Julie M.

2012-01-01

An atypical "swirling" phenomenon observed during the laser deposition of tungsten carbide-cobalt cermets by laser engineered net shaping (LENS®) was studied using in-situ high-speed thermal imaging. To provide fundamental insight into this phenomenon, the thermal behavior of pure cobalt during LENS was also investigated for comparison. Several factors were considered as the possible source of the observed differences. Of those, phase difference, material emissivity, momentum transfer, and free surface disruption from the powder jets, and, to a lesser extent, Marangoni convection were identified as the relevant mechanisms.

Investigation deuteron-induced reactions on cobalt

NASA Astrophysics Data System (ADS)

Ditrói, F.; Tárkányi, F.; Takács, S.; Hermanne, A.; Baba, M.; Ignatyuk, A. V.

2010-09-01

The excitation functions of deuteron-induced reactions were measured on metallic cobalt. Beyond the 56,57,58,60Co cobalt isotopes, we also identified 57Ni, 54Mn, 56Mn and 59Fe in the deuteron experiments. For the above radionuclides, the excitation functions in the measured energy range were determined and compared with the data found in the literature and with the results of model calculations (ALICE-IPPE, EMPIRE-D, EAF, and TALYS (TENDL)). The excitation functions agree with previous measurements; furthermore, we calculated the yield and thin layer activation (TLA) curves that are necessary for practical and industrial applications.

Water hyacinths and alligator weeds for removal of silver, cobalt, and strontium from polluted waters

NASA Technical Reports Server (NTRS)

Wolverton, B. C.; Mcdonald, R. C.

1975-01-01

Water hyacinths and alligator weeds demonstrated the ability to rapidly remove heavy metals from an aqueous system by root absorption and concentration. Water hyacinths demonstrated the ability to remove 0.439 mg of silver, 0.568 mg of cobalt, and 0.544 mg of strontium in an ionized form per gram of dry plant material in a 24-hour period. Alligator weeds removed a maximum of 0.439 mg of silver, 0.130 mg of cobalt, and 0.161 mg of strontium per gram of dry plant material per day.

Chemical and Phase Composition of Powders Obtained by Electroerosion Dispersion from WC - Co Alloys

NASA Astrophysics Data System (ADS)

Putintseva, M. N.

2004-03-01

The dependence of the chemical and phase composition of dispersed powders on the mode and medium of electroerosion dispersion and the content of cobalt in the initial alloy is considered. It is shown that the dissociation of carbon from tungsten carbide occurs even in dispersion in liquid hydrocarbon-bearing media (kerosene and industrial oils). The phase composition is primarily determined by the dispersion medium and the content of cobalt in the initial alloy. Compound tungsten-cobalt carbides and even a Co7W6 intermetallic are determined in all the powders.

[Dihydrotestosterone improves the osseointegration of cobalt-chromium implants].

PubMed

Maus, U M; Lühmann, M; Ohnsorge, J A K; Andereya, S; Schmidt, H; Zombory, G; Siebert, C; Niedhart, C

2013-02-01

The osseointegration of actually rarely implanted cobalt-chromium implants can be critical in an elderly population. The aim of our study was to evaluate the effect of preoperative testosterone treatment on the osseointegration of cobalt-chromium implants. Press-fit implantation of 1.6 mm-diameter cobalt-chromium-molybdenum (CoCrMo) implants was performed in rats without pre-treatment in one group (n = 10) and after pre-treatment with 1 mg dihydrotestosterone (DHT) 2 days before surgery in the other group (n = 10). After 14 days, the specimens were examined by a pull-out test, histology and histomorphometry. The biomechanical testing delivered inconsistent data leading to no significant difference (6.45 ± 6.94 N vs. 4.66 ± 3.77 N). Histology showed closed contact between surrounding tissue and the implants in both groups. The bone/implant contact area was significantly enhanced after treatment with DHT (42.23 % ± 9.25 vs. 57.57 % ± 16.71, p < 0.05), while the ratio of osteoid was reduced (38.68 % ± 16.7 vs. 27.38 % ± 13.02, not significant). Pre-treatment with DHT enhances osseointegration of cobalt-chromium implants through enhanced mineralisation of peri-implant tissue. The treatment might additionally shorten postoperative rehabilitation due to its positive effects on musculature. Georg Thieme Verlag KG Stuttgart · New York.

Controlling the size and magnetic properties of nano CoFe2O4 by microwave assisted co-precipitation method

NASA Astrophysics Data System (ADS)

Prabhakaran, T.; Mangalaraja, R. V.; Denardin, Juliano C.

2018-02-01

In this report, cobalt ferrite nanoparticles synthesized using microwave assisted co-precipitation method was reported. Efforts have been made to control the particles size, distribution, morphology and magnetic properties of cobalt ferrite nanoparticles by varying the concentration of NaOH solution and microwave irradiation time. It was observed that the rate of nucleation and crystal growth was influenced by the tuning parameters. In that way, the average crystallite size of single phase cobalt ferrite nanoparticles was controlled within 9-11 and 10-12 nm with an increase of base concentration and microwave irradiation time, respectively. A narrow size distribution of nearly spherical nanoparticles was achieved through the present procedure. A soft ferromagnetism at room temperature with the considerable saturation magnetization of 58.4 emu g-1 and coercivity of 262.7 Oe was obtained for the cobalt ferrites synthesized with 2.25 M of NaOH solution for 3 and 7 min of microwave irradiation time, respectively. The cobalt ferrite nanoparticles synthesized with a shorter reaction time of 3-7 min was found to be advantageous over other methods that involved conventional heating procedures and longer reaction time to achieve the better magnetic properties for the technological applications.

Bioinspired catalytic generation of high-valent cobalt-oxo species by the axially coordinated CoPc on pyridine-functionalized MWCNTs for the elimination of organic contaminants

NASA Astrophysics Data System (ADS)

Li, Nan; Wang, Ying; Wu, Chenren; Lu, Wangyang; Pei, Kemei; Chen, Wenxing

2018-03-01

Enzymes have always been a source of inspiration for the design and improvement of catalysts. Many examples are occurring in heme/non-heme metalloenzymes with the generation of active high-valent metal-oxo intermediates that are controlled by the surrounding amino acids/protein and axial residue ligands, facilitating the efficient oxidation of substrates in biochemical processes. Here, the high-valent cobalt-oxo species have been formed during the heterolysis of H2O2 activated by the bioinspired catalyst, axially coordinated cobalt phthalocyanine (CoPc) on pyridine-functionalized multi-walled carbon nanotubes (MWCNTs-Py), characterized by ultraviolet-visible and X-ray photoelectron spectroscopy. Formation process of the active cobalt-oxo species has been further confirmed by electrospray ionization mass spectrometry analysis and the results from the density functional theory (B3LYP/6-311G) calculations. Such high-valent cobalt-oxo species exhibit high reactivity and enough persistence for the oxidation of the target substrate, C.I. Acid Red 1. The oxidation products are nearly biodegradable small molecules identified by ultra-performance liquid chromatography/high-definition mass spectrometry. This strategy provides a foundation on developing efficient and persistent catalytic system, in particular oxidation processes based on the complex catalysts with N4 macrocycle structures.

A multisyringe flow-based system for kinetic-catalytic determination of cobalt(II).

PubMed

Chaparro, Laura; Ferrer, Laura; Leal, Luz; Cerdà, Víctor

2015-02-01

A kinetic-catalytic method for cobalt determination based on the catalytic effect of cobalt(II) on the oxidative coupling of 1,2-dihydroxyanthraquinone (alizarin) was automated exploiting multisyringe flow injection analysis (MSFIA). The proposed method was performed at pH 9.2, resulting in a discoloration process in the presence of hydrogen peroxide. The fixed-time approach was employed for analytical signal measurement. The spectrophotometric detection was used exploiting a liquid waveguide capillary cell (LWCC), of 1m optical length at 465 nm. The optimization was carried out by a multivariate approach, reaching critical values of 124 µmol L(-1) and 0.22 mol L(-1) for alizarin and hydrogen peroxide, respectively, and 67°C of reagent temperature. A sample volume of 150 µL was used allowing a sampling rate of 30h(-1). Under optimal conditions, calibration curve was linear in the range of 1-200 µg L(-1) Co, achieving a DL of 0.3 µg L(-1) Co. The repeatability, expressed as relative standard deviation (RSD) was lower than 1%. The proposed analytical procedure was applied to the determination of cobalt in cobalt gluconate and different forms of vitamin B12, cyanocobalamin and hydroxicobalamin with successful results showing recoveries around 95%. Copyright © 2014 Elsevier B.V. All rights reserved.

Sorption of copper, zinc and cobalt by oat and oat products.

PubMed

Górecka, Danuta; Stachowiak, Jadwiga

2002-04-01

We determined copper, zinc and cobalt sorption by oat and its products under variable pH conditions as well as the content of neutral dietary fiber (NDF) and its fractional composition. Adsorbents in a model sorption system were: oat, dehulled oat, oats bran and oats flakes. Three various buffers (pH 1.8, 6.6 and 8.7) were used as dispersing solutions. Results collected during this study indicate that copper, zinc and cobalt sorption is significantly affected by the type of cereal raw material. Zinc and copper ions are subjected to higher sorption than cobalt ions. Examined metal ions were subjected to high sorption under conditions corresponding to the duodenum environment (pH 8.7), regardless of the kind of adsorbent. A little lower sorption capacity is observed under conditions close to the neutral environment, while the lowest one is found in environment reflecting conditions of stomach juice (pH 1.8). Zinc ions are bound intensively by dehulled oat, while oats flakes bound mostly copper and cobalt, independently on environmental conditions. Contents of dietary fiber in oat, dehulled oat, oat bran and oat flakes were: 40.1, 19.3, 20.3 and 14.3%, respectively. The dominating fraction in all oat products was the fraction of hemicelluloses. The content of remaining fractions varies in dependence on the product.

Cobalt Oxide on N-Doped Carbon for 1-Butene Oligomerization to Produce Linear Octenes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Dongting; Xu, Zhuoran; Chada, Joseph P.

Cobalt oxide supported on N-doped carbon catalysts were investigated for 1-butene oligomerization. The materials were synthesized by treating activated carbon with nitric acid and subsequently with NH3 at 200, 400, 600, and 800 °C, followed by impregnation with cobalt. The 1-butene oligomerization selectivity increased with ammonia treatment temperature of the carbon support. The oligomerization selectivity of cobalt oxide on N-doped carbon synthesized at 800 °C (800A-CoOx/N-C) is 2.6 times higher than previously reported cobalt oxide on N-doped carbon synthesized with NH4OH (2A-CoOx/N-C). Over 70% of the butene dimers were linear C8 olefins for all catalysts. The oligomerization selectivity increased withmore » 1-butene conversion. The catalysts were characterized by elemental analysis, N2 adsorption, X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS). The nitrogen content of the catalysts increases with ammonia treatment temperature as confirmed by elemental analysis. The surface content of pyridinic nitrogen with a binding energy of 398.4 ± 0.1 eV increased with ammonia treatment temperature as evidenced by deconvolution of N 1s XPS spectra.« less

Neuropsychiatric symptoms following metal-on-metal implant failure with cobalt and chromium toxicity.

PubMed

Green, Ben; Griffiths, Emily; Almond, Solomon

2017-01-24

There were at least 31,171 metal-on-metal (MoM) hip implants in the UK between 2003 and 2011. Some of these were subject to failure and widescale recalls and revisions followed. This is a presentation of ten cases (mean age 60 years) where we evaluated neuropsychiatric morbidity following metal-on-metal hip implant failure and revision. Implants were ASR total hip replacement (acetabular implant, taper sleeve adaptor and unipolar femoral implants) performed between 2005 and 2009. This case series describes, for the first time, neuropsychiatric complications after revision where there has been cobalt and chromium toxicity. Pre-revision surgery, nine patients had toxic levels of chromium and cobalt (mean level chromium 338 nmol/l, mean cobalt 669.4 nmol/l). Depression assessment showed 9 of 9 respondents fulfilled the BDI criteria for depression and 3 of these were being treated. 7 of 9 patients showing short term memory deficit with mean mini mental state examination score of 24.2. The normal population mean MMSE for this group would be expected to be 28 with <25 indicating possible dementia. We found neurocognitive and depressive deficits after cobalt and chromium metallosis following MoM implant failure. Larger studies of neurocognitive effects are indicated in this group. There may be implications for public health.

Cobalt nanoparticles encapsulated in nitrogen-rich carbon nanotubes as efficient catalysts for organic pollutants degradation via sulfite activation.

PubMed

Wu, Deming; Ye, Peng; Wang, Manye; Wei, Yi; Li, Xiaoxia; Xu, Aihua

2018-06-15

The activation of sulfite by heterogeneous catalysts displays a great potential in the development of new sulfate radials based technologies for wastewater treatment. Herein, cobalt nanoparticles embedded in N-doped carbon nanotubes (Co@NC) were prepared by a simple pyrolysis method. Due to the synergistic effects of the cobalt nanoparticles and N-doped carbon nanotubes, the Co@NC catalyst intrinsically shows an outstanding efficiency, excellent reusability and high stability in the catalytic oxidation of methyl orange (MO) in the presence of sulfite and dioxygen. The structure and efficiency of the catalyst was significantly affected by the content of cobalt and pyrolysis temperature. Several quenching experiments and electron paramagnetic resonance were carried out to investigate the catalytic mechanism. It is found that hydroxyl and sulfate radicals worked together to degrade MO in the system. The formation and decomposition of peroxymonosulfate may be an important route of these reactive radicals production. The effect of different anions, bicarbonate concentration, initial solution pH and dye types on the performance of the catalyst was also studied. This study can open a new approach for design and preparation of encapsulated cobalt in carbon materials as effective catalysts for pollutants degradation via sulfite activation. Copyright © 2018 Elsevier B.V. All rights reserved.

Fe(II)-substituted cobalt ferrite nanoparticles against multidrug resistant microorganisms

NASA Astrophysics Data System (ADS)

Žalnėravičius, Rokas; Paškevičius, Algimantas; Mažeika, Kęstutis; Jagminas, Arūnas

2018-03-01

The present study is focused on the determination the influence of cobalt content in the magnetic cobalt ferrite nanoparticles (Nps) on their antibacterial efficiency against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria and several Candida species, in particular C. parapsilosis and C. albicans. For the synthesis of Fe(II) substituted cobalt ferrite Nps by co-precipitation way, the L-lysine was used as the capping biocompatible agent and the particle size was successfully controlled to be in the range of 5-6.4 nm. The antimicrobial efficiencies of the CoxFe1-xFe2O4@Lys Nps, where x varies from 0.2 to 1.0, were evaluated through the quantitative analysis by comparing with that of Fe3O4@Lys Nps and L-lysine. In this way, it was evidenced that increase in the Co2+ content in the similar sized cobalt ferrite Nps resulted in an increase in their antimicrobial potency into 93.1-86.3 % for eukaryotic and into 96.4-42.7 % for prokaryotic strains. For characterization the composition, structure, and morphology of the tested herein Nps inductively coupled plasma optical emission spectrometry, X-ray diffraction, high-resolution transmission electron microscopy, Mössbauer, and FTIR spectroscopy techniques were conferred.

A metal-organic tetrahedron as a redox vehicle to encapsulate organic dyes for photocatalytic proton reduction.

PubMed

Jing, Xu; He, Cheng; Yang, Yang; Duan, Chunying

2015-03-25

The design of artificial systems that mimic highly evolved and finely tuned natural photosynthetic systems is a subject of intensive research. We report herein a new approach to constructing supramolecular systems for the photocatalytic generation of hydrogen from water by encapsulating an organic dye molecule into the pocket of a redox-active metal-organic polyhedron. The assembled neutral Co4L4 tetrahedron consists of four ligands and four cobalt ions that connect together in alternating fashion. The cobalt ions are coordinated by three thiosemicarbazone NS chelators and exhibit a redox potential suitable for electrochemical proton reduction. The close proximity between the redox site and the photosensitizer encapsulated in the pocket enables photoinduced electron transfer from the excited state of the photosensitizer to the cobalt-based catalytic sites via a powerful pseudo-intramolecular pathway. The modified supramolecular system exhibits TON values comparable to the highest values reported for related cobalt/fluorescein systems. Control experiments based on a smaller tetrahedral analogue of the vehicle with a filled pocket and a mononuclear compound resembling the cobalt corner of the tetrahedron suggest an enzymatic dynamics behavior. The new, well-elucidated reaction pathways and the increased molarity of the reaction within the confined space render these supramolecular systems superior to other relevant systems.

77 FR 64311 - Potential Market Impact of the Proposed Fiscal Year 2014 Annual Materials Plan; National Defense...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-19

...,000 (5) Cadmium Zinc Tellurium (CZT) substrates.. cm\\2\\ 24,000 (6) Lithium Cobalt Oxide (LCO) Kg 750 (6) Lithium Nickel Cobalt Aluminum Oxide kg 540 (6) (NCA). Mesocarbon Microbeads (MCMB) kg 648 (6...

Fischer–Tropsch synthesis: Effect of ammonia on supported cobalt catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pendyala, Venkat Ramana Rao; Jacobs, Gary; Bertaux, Clement

The effect of ammonia in syngas on the performance of various supported cobalt catalysts (i.e., Al 2O 3, TiO 2 and SiO 2) was investigated during Fischer-Tropsch synthesis (FTS) using a continuously stirred tank reactor (CSTR). The addition of ammonia (10 ppmv NH 3) caused a significant deactivation for all supported cobalt catalysts, but the rate of deactivation was higher for the silica-supported catalysts relative to the alumina and titania-supported catalysts used in this work. Ammonia addition had a positive effect on product selectivity (i.e., lower light gas products and higher C 5+) for alumina and titania-supported catalysts compared tomore » ammonia free conditions, whereas, the addition of ammonia increased lighter hydrocarbon (C 1-C 4) products and decreased higher hydrocarbon (C 5+) selectivity compared to ammonia-free synthesis conditions for the silica-supported catalyst. For alumina and titania-supported catalysts, the activity almost recovered with mild in-situ hydrogen treatment of the ammonia exposed catalysts. For the silica-supported catalyst, the loss of activity is somewhat irreversible (i.e., cannot be regained after the mild hydrogen treatment). Addition of ammonia led to a significant loss in BET surface area and changes in pore diameter (consistent with pore collapse of a fraction of pores into the microporous range as described in the literature), as well as formation of catalytically inactive cobalt support compounds for the silica-supported catalyst. On the other hand, the pore characteristics of alumina and titania-supported catalysts were not significantly changed. In conclusion, XANES results of the ammonia exposed silica-supported catalysts further confirm the formation of cobalt-support compounds (cobalt silicates).« less

Patch test reactivity to a cobalt-chromium-molybdenum alloy and stainless steel in metal-allergic patients in correlation to the metal ion release.

PubMed

Summer, Burkhard; Fink, Ulrich; Zeller, Richard; Rueff, Franziska; Maier, Sonja; Roider, Gabriele; Thomas, Peter

2007-07-01

Nickel, chromium, and cobalt released from stainless steel and CoCrMo alloys have been postulated to trigger hypersensitivity reactions. The objective of this study was to assess the ion release from a CoCrMo alloy and stainless steel in vitro and the cutaneous reactivity to it by patch test. 52 metal-allergic patients and 48 non-allergic controls were patch tested to stainless steel and CoCrMo discs. In addition, using atomic absorption spectrometry, the release of nickel, cobalt, and chromium from both materials was assessed upon 2-day exposure to distilled water, artificial sweat (AS), and cell culture medium. There was low nickel ion release from stainless steel (0.3-0.46 microg/cm(2)/2 days) and CoCrMo discs (up to 0.33 microg/cm(2)/2 days) into the different elution media. Chromium release from the 2 materials was also very low (0.06-0.38 microg/cm(2)/2 days from stainless steel and 0.52-1.36 microg/cm(2)/2 days from CoCrMo alloy). In contrast, AS led to abundant cobalt release (maximally 18.94 microg/cm(2)/2 days) from the CoCrMo discs, with concomitant eczematous reaction upon patch testing: 0 of the 52 metal-allergic patients reacted to stainless steel discs and 5 of the 52 patients to CoCrMo discs (all 5 patients were cobalt allergic and 3 also nickel and chromium allergic). None of the controls reacted to the discs. Apart from nickel being a focus of allergological research, our results point to the possibly underestimated association of cobalt release and potential hyperreactivity to CoCrMo alloy.

Electron-transfer reactions of cobalt(III) complexes. 1. The kinetic investigation of the reduction of various surfactant cobalt(III) complexes by iron(II) in surface active ionic liquids

NASA Astrophysics Data System (ADS)

Nagaraj, Karuppiah; Senthil Murugan, Krishnan; Thangamuniyandi, Pilavadi; Sakthinathan, Subramanian

2015-05-01

The kinetics of outer sphere electron transfer reaction of surfactant cobalt(III) complex ions, cis-[Co(en)2(C12H25NH2)2]3+ (1), cis-[Co(dp)2(C12H25NH2)2]3+ (2), cis-[Co(trien)(C12H25NH2)2]3+ (3), cis-[Co(bpy)2(C12H25NH2)2]3+ (4) and cis-[Co(phen)2(C12H25NH2)2]3+ (5) (en: ethylenediamine, dp: diaminopropane, trien : triethylenetetramine, bpy: 2,2‧-bipyridyl, phen: 1,10-phenanthroline and C12H25NH2 : dodecylamine) have been interrogated by Fe2+ ion in ionic liquid (1-butyl-3-methylimidazoliumbromide) medium at different temperatures (298, 303, 308, 313, 318 and 323 K) by the spectrophotometry method under pseudo first order conditions using an excess of the reductant. Experimentally the reactions were found to be of second order and the electron transfer as outer sphere. The second order rate constant for the electron transfer reaction in ionic liquids was found to increase with increase in the concentration of all these surfactant cobalt(III) complexes. Among these complexes (from en to phen ligand), complex containing the phenanthroline ligand rate is higher compared to other complexes. By assuming the outer sphere mechanism, the results have been explained based on the presence of aggregated structures containing cobalt(III) complexes at the surface of ionic liquids formed by the surfactant cobalt(III) complexes in the reaction medium. The activation parameters (enthalpy of activation ΔH‡ and entropy of activation ΔS‡) of the reaction have been calculated which substantiate the kinetics of the reaction.

Fischer–Tropsch synthesis: Effect of ammonia on supported cobalt catalysts

DOE PAGES

Pendyala, Venkat Ramana Rao; Jacobs, Gary; Bertaux, Clement; ...

2016-02-22

The effect of ammonia in syngas on the performance of various supported cobalt catalysts (i.e., Al 2O 3, TiO 2 and SiO 2) was investigated during Fischer-Tropsch synthesis (FTS) using a continuously stirred tank reactor (CSTR). The addition of ammonia (10 ppmv NH 3) caused a significant deactivation for all supported cobalt catalysts, but the rate of deactivation was higher for the silica-supported catalysts relative to the alumina and titania-supported catalysts used in this work. Ammonia addition had a positive effect on product selectivity (i.e., lower light gas products and higher C 5+) for alumina and titania-supported catalysts compared tomore » ammonia free conditions, whereas, the addition of ammonia increased lighter hydrocarbon (C 1-C 4) products and decreased higher hydrocarbon (C 5+) selectivity compared to ammonia-free synthesis conditions for the silica-supported catalyst. For alumina and titania-supported catalysts, the activity almost recovered with mild in-situ hydrogen treatment of the ammonia exposed catalysts. For the silica-supported catalyst, the loss of activity is somewhat irreversible (i.e., cannot be regained after the mild hydrogen treatment). Addition of ammonia led to a significant loss in BET surface area and changes in pore diameter (consistent with pore collapse of a fraction of pores into the microporous range as described in the literature), as well as formation of catalytically inactive cobalt support compounds for the silica-supported catalyst. On the other hand, the pore characteristics of alumina and titania-supported catalysts were not significantly changed. In conclusion, XANES results of the ammonia exposed silica-supported catalysts further confirm the formation of cobalt-support compounds (cobalt silicates).« less

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

PubMed

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

2016-02-01

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

Physical setting and natural sources of exposure to carcinogenic trace elements and radionuclides in Lahontan Valley, Nevada

USGS Publications Warehouse

Seiler, Ralph L.

2012-01-01

In Lahontan Valley, Nevada, arsenic, cobalt, tungsten, uranium, radon, and polonium-210 are carcinogens that occur naturally in sediments and groundwater. Arsenic and cobalt are principally derived from erosion of volcanic rocks in the local mountains and tungsten and uranium are derived from erosion of granitic rocks in headwater reaches of the Carson River. Radon and 210Po originate from radioactive decay of uranium in the sediments. Arsenic, aluminum, cobalt, iron, and manganese concentrations in household dust suggest it is derived from the local soils. Excess zinc and chromium in the dust are probably derived from the vacuum cleaner used to collect the dust, or household sources such as the furnace. Some samples have more than 5 times more cobalt in the dust than in the local soil, but whether the source of the excess cobalt is anthropogenic or natural cannot be determined with the available data. Cobalt concentrations are low in groundwater, but arsenic, uranium, radon, and 210Po concentrations often exceed human-health standards, and sometime greatly exceed them. Exposure to radon and its decay products in drinking water can vary significantly depending on when during the day that the water is consumed. Although the data suggests there have been no long term changes in groundwater chemistry that corresponds to the Lahontan Valley leukemia cluster, the occurrence of the very unusual leukemia cluster in an area with numerous 210Po and arsenic contaminated wells is striking, particularly in conjunction with the exceptionally high levels of urinary tungsten in Lahontan Valley residents. Additional research is needed on potential exposure pathways involving food or inhalation, and on synergistic effects of mixtures of these natural contaminants on susceptibility to development of leukemia.

Physical setting and natural sources of exposure to carcinogenic trace elements and radionuclides in Lahontan Valley, Nevada.

PubMed

Seiler, Ralph

2012-04-05

In Lahontan Valley, Nevada, arsenic, cobalt, tungsten, uranium, radon, and polonium-210 are carcinogens that occur naturally in sediments and groundwater. Arsenic and cobalt are principally derived from erosion of volcanic rocks in the local mountains and tungsten and uranium are derived from erosion of granitic rocks in headwater reaches of the Carson River. Radon and 210Po originate from radioactive decay of uranium in the sediments. Arsenic, aluminum, cobalt, iron, and manganese concentrations in household dust suggest it is derived from the local soils. Excess zinc and chromium in the dust are probably derived from the vacuum cleaner used to collect the dust, or household sources such as the furnace. Some samples have more than 5 times more cobalt in the dust than in the local soil, but whether the source of the excess cobalt is anthropogenic or natural cannot be determined with the available data. Cobalt concentrations are low in groundwater, but arsenic, uranium, radon, and 210Po concentrations often exceed human-health standards, and sometime greatly exceed them. Exposure to radon and its decay products in drinking water can vary significantly depending on when during the day that the water is consumed. Although the data suggests there have been no long term changes in groundwater chemistry that corresponds to the Lahontan Valley leukemia cluster, the occurrence of the very unusual leukemia cluster in an area with numerous 210Po and arsenic contaminated wells is striking, particularly in conjunction with the exceptionally high levels of urinary tungsten in Lahontan Valley residents. Additional research is needed on potential exposure pathways involving food or inhalation, and on synergistic effects of mixtures of these natural contaminants on susceptibility to development of leukemia. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Cobalt deposition in mineralized bone tissue after metal-on-metal hip resurfacing: Quantitative μ-X-ray-fluorescence analysis of implant material incorporation in periprosthetic tissue.

PubMed

Hahn, Michael; Busse, Björn; Procop, Mathias; Zustin, Jozef; Amling, Michael; Katzer, Alexander

2017-10-01

Most resurfacing systems are manufactured from cobalt-chromium alloys with metal-on-metal (MoM) bearing couples. Because the quantity of particulate metal and corrosion products which can be released into the periprosthetic milieu is greater in MoM bearings than in metal-on-polyethylene (MoP) bearings, it is hypothesized that the quantity and distribution of debris released by the MoM components induce a compositional change in the periprosthetic bone. To determine the validity of this claim, nondestructive µ-X-ray fluorescence analysis was carried out on undecalcified histological samples from 13 femoral heads which had undergone surface replacement. These samples were extracted from the patients after gradient time points due to required revision surgery. Samples from nonintervened femoral heads as well as from a MoP resurfaced implant served as controls. Light microscopy and µ-X-ray fluorescence analyses revealed that cobalt debris was found not only in the soft tissue around the prosthesis and the bone marrow, but also in the mineralized bone tissue. Mineralized bone exposed to surface replacements showed significant increases in cobalt concentrations in comparison with control specimens without an implant. A maximum cobalt concentration in mineralized hard tissue of up to 380 ppm was detected as early as 2 years after implantation. Values of this magnitude are not found in implants with a MoP surface bearing until a lifetime of more than 20 years. This study demonstrates that hip resurfacing implants with MoM bearings present a potential long-term health risk due to rapid cobalt ion accumulation in periprosthetic hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1855-1862, 2017. © 2016 Wiley Periodicals, Inc.

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

PubMed Central

Permenter, Matthew G.; Dennis, William E.; Sutto, Thomas E.; Jackson, David A.; Lewis, John A.; Stallings, Jonathan D.

2013-01-01

Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies. PMID:24386269

Aluminium - Cobalt-Pillared Clay for Dye Filtration Membrane

NASA Astrophysics Data System (ADS)

Darmawan, A.; Widiarsih

2018-04-01

The manufacture of membrane support from cobalt aluminium pillared clay has been conducted. This research was conducted by mixing a clay suspension with pillared solution prepared from the mixture of Co(NO3)2.6H2O and AlCl3.6H2O. The molar ratio between Al and Co was 75:25 and the ratio of [OH-]/[metal] was 2. The clay suspension was stirred for 24 hours at room temperature, filtered and dried. The dried clay was then calcined at 200°C, 300°C and 400°C with a ramp rate of 2°C/min. Aluminium-cobalt-pillared clay was then characterized by XRD and GSA and moulded become a membrane support for subsequent tests on dye filtration. The XRD analysis showed that basal spacing (d 001) value of aluminium cobalt was 19.49 Å, which was higher than the natural clay of 15.08Å however, the basal spacing decreased with increasing calcination temperature. The result of the GSA analysis showed that the pore diameter of the aluminium cobalt pillared clay membrane was almost the same as that of natural clay that were 34.5Å and 34.2Å, respectively. Nevertheless, the pillared clay has a more uniform pore size distribution. The results of methylene blue filtration measurements demonstrated that the membrane filter support could well which shown by a clear filtrate at all concentrations tested. The value of rejection and flux decreased with the increasing concentration of methylene blue. The values of dye rejection and water flux reached 99.89% and 5. 80 x 10-6 kg min-1, respectively but they decreased with increasing concentration of methylene blue. The results of this study indicates that the aluminium-pillared clay cobalt could be used as membrane materials especially for ultrafiltration.

Water splitting: Taking cobalt in isolation

NASA Astrophysics Data System (ADS)

Wang, Aiqin; Zhang, Tao

2016-01-01

The sustainable production of hydrogen is key to the delivery of clean energy in a hydrogen economy; however, lower-cost alternatives to platinum electrocatalysts are needed. Now, isolated, earth-abundant cobalt atoms dispersed over nitrogen-doped graphene are shown to efficiently electrolyse water to generate hydrogen.

Cobalt Fischer-Tropsch catalysts having improved selectivity

DOEpatents

Miller, James G.; Rabo, Jule A.

1989-01-01

A cobalt Fischer-Tropsch catalyst having an improved steam treated, acid extracted LZ-210 support is taught. The new catalyst system demonstrates improved product selectivity at Fischer-Tropsch reaction conditions evidenced by lower methane production, higher C.sub.5.sup.+ yield and increased olefin production.

Radionuclide deposition control

DOEpatents

Brehm, William F.; McGuire, Joseph C.

1980-01-01

The deposition of radionuclides manganese-54, cobalt-58 and cobalt-60 from liquid sodium coolant is controlled by providing surfaces of nickel or high nickel alloys to extract the radionuclides from the liquid sodium, and by providing surfaces of tungsten, molybdenum or tantalum to prevent or retard radionuclide deposition.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

The surface sulfur doping induced enhanced performance of cobalt catalysts in oxygen evolution reactions.

PubMed

Al-Mamun, Mohammad; Zhu, Zhengju; Yin, Huajie; Su, Xintai; Zhang, Haimin; Liu, Porun; Yang, Huagui; Wang, Dan; Tang, Zhiyong; Wang, Yun; Zhao, Huijun

2016-08-04

A novel surface sulfur (S) doped cobalt (Co) catalyst for the oxygen evolution reaction (OER) is theoretically designed through the optimisation of the electronic structure of highly reactive surface atoms which is also validated by electrocatalytic OER experiments.

Influence of cobalt doping on structural and magnetic properties of BiFeO3 nanoparticles

NASA Astrophysics Data System (ADS)

Khan, U.; Adeela, N.; Javed, K.; Riaz, S.; Ali, H.; Iqbal, M.; Han, X. F.; Naseem, S.

2015-11-01

Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe1- δ Co δ O3 (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO3. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller's law, while modified Bloch's model was employed for saturation magnetization in temperature range of 5-300 K.

Morphology-Tuned Synthesis of Nickel Cobalt Selenides as Highly Efficient Pt-Free Counter Electrode Catalysts for Dye-Sensitized Solar Cells.

PubMed

Qian, Xing; Li, Hongmei; Shao, Li; Jiang, Xiancai; Hou, Linxi

2016-11-02

In this work, morphology-tuned ternary nickel cobalt selenides based on different Ni/Co molar ratios have been synthesized via a simple precursor conversion method and used as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). The experimental facts and mechanism analysis clarified the possible growth process of product. It can be found that the electrochemical performance and structures of ternary nickel cobalt selenides can be optimized by tuning the Ni/Co molar ratio. Benefiting from the unique morphology and tunable composition, among the as-prepared metal selenides, the electrochemical measurements showed that the ternary nickel cobalt selenides exhibited a more superior electrocatalytic activity in comparison with binary Ni and Co selenides. In particular, the three-dimensional dandelion-like Ni 0.33 Co 0.67 Se microspheres delivered much higher power conversion efficiency (9.01%) than that of Pt catalyst (8.30%) under AM 1.5G irradiation.

Thermogravimetric analysis of the interaction of ferromagnetic metal atom and multiwalled carbon nanotubes.

PubMed

Rawat, Naveen; Gudyaka, Russel; Kumar, Mohit; Joshi, Bharat; Santhanam, Kalathur S V

2008-04-01

This paper describes the thermal oxidative behavior of atomized iron or atomized cobalt in the presence of multiwalled carbon nanotubes (MWCNT). The thermogravimetric analysis shows the atomized iron thermal oxidation starts at about 500 degrees C that is absent when the atomized iron is sintered with multiwalled carbon naonotubes. The thermal oxidation of iron in the sintered samples requires the collapse of the multiwalled carbon nanotubes. A similar behavior is observed with atomized cobalt when its oxidation requires the collapse of the nanotubes. This thermal oxidative shift is interpreted as due to the atomized iron or atomized cobalt atom experiencing extensive overlap and confinement effect with multiwalled carbon nanotubes causing a spin transfer. This confinement effect is suggested to produce a transformation of iron from the outermost electronic distribution of 3d64s2 to an effective configuration of 3d84s0 and for cobalt 3d74s2 to 3d94s0 producing spintronics effect.

Microstructural development of cobalt ferrite ceramics and its influence on magnetic properties

NASA Astrophysics Data System (ADS)

Kim, Gi-Yeop; Jeon, Jae-Ho; Kim, Myong-Ho; Suvorov, Danilo; Choi, Si-Young

2013-11-01

The microstructural evolution and its influence on magnetic properties in cobalt ferrite were investigated. The cobalt ferrite powders were prepared via a solid-state reaction route and then sintered at 1200 °C for 1, 2, and 16 h in air. The microstructures from sintered samples represented a bimodal distribution of grain size, which is associated with abnormal grain growth behavior. And thus, with increasing sintering time, the number and size of abnormal grains accordingly increased but the matrix grains were frozen with stagnant grain growth. In the sample sintered for 16 h, all of the matrix grains were consumed and the abnormal grains consequently impinged on each other. With the appearance of abnormal grains, the magnetic coercivity significantly decreased from 586.3 Oe (1 h sintered sample) to 168.3 Oe (16 h sintered sample). This is due to the magnetization in abnormal grains being easily flipped. In order to achieve high magnetic coercivity of cobalt ferrite, it is thus imperative to fabricate the fine and homogeneous microstructure.

Investigation of a Spin Transition in a LaCoO3 Single Crystal by the Method of X-Ray Magnetic Circular Dichroism at the Cobalt K- and L 2,3-Edges

NASA Astrophysics Data System (ADS)

Sikolenko, V. V.; Troyanchuk, I. O.; Karpinsky, D. V.; Rogalev, A.; Wilhelm, F.; Rosenberg, R.; Prabhakaran, D.; Efimova, E. A.; Efimov, V. V.; Tiutiunnikov, S. I.; Bobrikov, I. A.

2018-02-01

Spin transitions of cobalt ions in LaCoO3 single crystals have been studied by the method of X-ray magnetic circular dichroism (XMCD) at the K- and L 2,3-edges of Co3+ ions. The orbital momentum of cobalt ions obtained for the K-edge at the 3 d level in the region of the spin transition in the temperature range from 25 to 120 K increases by a factor of approximately 1.6, whereas the slope of the magnetization curve value in the same temperature range and magnetic field increases by a factor of more than 10. XMCD experiments at the cobalt L 2,3-edges demonstrate gradual growth of the ratio of the orbital momentum to the spin one L/ S from 0.48 to 0.53 in the temperature range from 60 K to 120 K.

Magnetic hydrogels from alkyne/cobalt carbonyl-functionalized ABA triblock copolymers

DOE PAGES

Jiang, Bingyin; Hom, Wendy L.; Chen, Xianyin; ...

2016-03-09

A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)- block-poly(ethylene oxide)- block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. PES n[Co 2(CO) 6] x-EO 800-PES n[Co 2(CO) 6] x ABA triblock copolymer/cobalt adducts (10–67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co 2(CO) 8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linkedmore » materials with water. Furthermore, swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.« less

Effect of reduced cobalt contents on hot isostatically pressed powder metallurgy U-700 alloys

NASA Technical Reports Server (NTRS)

Harf, F. H.

1982-01-01

The effect of reducing the cobalt content of prealloyed powders of UDIMET 700 (U-700) alloys to 12.7, 8.6, 4.3, and 0% was examined. The powders were hot isostatically pressed into billets, which were given heat treatments appropriate for turbine disks, namely partial solutioning at temperatures below the gamma prime solvus and four step aging treatments. Chemical analyses, metallographic examinations, and X-ray diffraction measurements were performed on the materials. Minor effects on gamma prime content and on room temperature and 650 C tensile properties were observed. Creep rupture lives at 650 C reached a maximum at the 8.4% concentration, while at 760 C a maximum in life was reached at the 4.3% cobalt level. Minimum creep rates increased with decreasing cobalt content at both test temperatures. Extended exposures at 760 and 815 C resulted in decreased tensile strengths and rupture lives for all alloys. Evidence of sigma phase formation was also found.

Biosynthesis of cobalt oxide nanoparticles using endophytic fungus Aspergillus nidulans.

PubMed

Vijayanandan, Ajuy Sundar; Balakrishnan, Raj Mohan

2018-07-15

Metallic oxide nanoparticles have profound applications in electrochemical devices, supercapacitors, biosensors and batteries. Though four fungi were isolated from Nothapodytes foetida, Aspergillus nidulans was found to be suitable for synthesis of cobalt oxide nanoparticles, as it has proficient tolerance towards metal under study. The broth containing precursor solution and organism Aspergillus nidulans had changed from pink to orange indicating the formation of nanoparticles. Characterization by x-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and energy dispersive x-ray analysis (EDX) confirmed the formation of spinel cobalt oxide nanoparticles at an average size of 20.29 nm in spherical shape with sulfur-bearing proteins acting as a capping agent for the synthesized nanoparticles. The nanoparticles could be applied in energy storage, as a specific capacitance of 389 F/g showed competence. The study was a greener attempt to synthesize cobalt oxide nanoparticles using endophytic fungus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Superposition model analysis of zero field splitting for Mn2+ in some host single crystals

NASA Astrophysics Data System (ADS)

Bansal, R. S.; Ahlawat, P.; Bharti, M.; Hooda, S. S.

2013-07-01

The Newman superposition model has been used to investigate the substitution of Mn2+ for Zn2+ site in ammonium tetra flurozincate dihydrate and for Co2+ site in cobalt ammonium phosphate hexahydrate and cobalt potassium phosphate hexahydrate single crystals. The calculated values of zero field splitting parameter b 2 0 at room temperature fit the experimental data with average intrinsic parameters overline{b}2 (F) = -0.0531 cm-1 for fluorine and overline{b}2 (O) = -0.0280 cm-1 for oxygen, taken t 2 = 7 for Mn2+ doped in ammonium tetra fluorozincate dihydrate single crystals. The values of overline{b}2 determined for Mn2+ doped in cobalt ammonium phosphate hexahydrate are -0.049 cm-1 for site I and -0.045 cm-1 for site II and in cobalt pottasium phosphate hexahydrate single crystals it is found to be overline{b}2 = -0.086 cm-1. We find close agreement between theoretical and experimental values of b 2 0.

Preparation and use of tetra-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents

DOEpatents

Miller, Rebecca L.; Pinkerton, Anthony B.; Abney, Kent D.; Kinkead, Scott A.

1997-01-01

Preparation and use of tetra-C-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents. Tetra-C-alkyl derivatives of cobalt dicarbollide, Co(C.sub.2 R.sub.2 B.sub.9 H.sub.9).sub.2.sup.- (CoB.sub.2 R.sub.4.sup.- ; R=CH.sub.3 and C.sub.6 H.sub.13) are demonstrated to be significant cesium and strontium extractants from acidic and alkaline solutions into non-toxic organic solvent systems. Extractions using mesitylene and diethylbenzene are compared to those with nitrobenzene as the organic phase. CoB.sub.2 -hexyl.sub.4.sup.- in diethylbenzene shows improved selectivity (10.sup.4) for Cs over Na in acidic solution. In dilute alkaline solution, CoB.sub.2 -hexyl.sub.4.sup.- extracts Cs less efficiently, but more effectively removes Sr from higher base concentrations. A general synthesis of tetra-C-alkyl cobalt dicarbollides is described.