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RF values of EDTA complexes of some common metal ions in seven solvent systems are given. The separation of Al and Be EDTA complexes has been achieved in different ratios by paper chromatography. Paper electrophoresis is also performed in four solvent systems to study the separation of EDTA complexes of metal ions.

Heavy metal pollution of civil and industrial wastewaters represents a major problem for the environment since metal ions are non-biodegradable, have a very high toxicity, and some of them have proved to be carcinogenic. If directly discharged in sewers, metal ions may seriously damage the subsequent biological treatments in depuration plants and render treatment sludge not reusable for agriculture. On the contrary, water and sludge reuse should be a primary criterion when planning improvements for wastewater treatment plants and their adaptation to new standards. In this paper, the membrane performance (a monotubular ceramic membrane of molecular weight cutoff: 210 kDa) is investigated in the removal of nickel and cobalt ions from synthetic liquid wastes aimed at water reuse using a micellar-enhanced ultrafiltration process. The ultrafiltration membrane is used with adding an anionic surfactant (sodium dodecyl sulfate (SDS)) in a laboratory scale experimental device. The synthetic liquid waste co...

Vascular endothelial growth factor (VEGF) A is a master regulator of neovascularization and angiogenesis. VEGFA is potently induced by hypoxia and by pathological conditions including diabetic retinopathy and tumorigenesis. Fine-tuning of VEGFA expression by different stimuli is important for maintaining tissue vascularization and organ homeostasis. Here, we tested the effect of the hypoxia mimetic cobalt chloride (CoCl2) on VEGFA expression in human cervical carcinoma HeLa cells. We found that CoCl2 increased the levels of VEGFA mRNA and VEGFA protein without affecting VEGFA mRNA stability. Biotin pulldown analysis to capture the RNA-binding proteins (RBPs) bound to VEGFA mRNA followed by mass spectrometry analysis revealed that the RBP HuR [human antigen R, a member of the embryonic lethal abnormal vision (ELAV) family of proteins], interacts with VEGFA mRNA. VEGFA mRNA-tagging experiments showed that exposure to CoCl2 increases the interaction of HuR with VEGFA mRNA and promoted the colocalization of HuR and the distal part of the VEGFA 3′-untranslated region (UTR) in the cytoplasm. We propose that under hypoxia-like conditions, HuR enhances VEGFA mRNA translation.

Laboratory flotation tests with copper–cobalt oxidized ore from the Luiswishi deposit in the Katanga province were done using process water being recycled to different degrees. Grade and recovery of copper and cobalt were followed by 10, 20 and 80% process to fresh water addition with the results from these conditions being compared to those without water recycling. When process water was recycled at 10%, 83.7% copper and 84.1% cobalt were recovered at the rougher stage bringing the cleaner stage to a concentrate with recovery of 53 and 60% for copper and cobalt, respectively. However, recycling process water, up to 20 and 80%, has reduced the recovery of copper in the final concentrate to 23 and 6%, respectively, and of cobalt to 46 and 27%, respectively. Monitoring of dissolved oxygen content, pulp pH and Es potential during flotation, coupled with thermodynamic estimation of the predominant chemical compounds in the system, has enabled to evaluate the effects on flotation from the undesirable c...

We have investigated the dependence of the rate of the production of biogas upon the concentration of nickel, cobalt and iron at sub-toxic concentration and monitored its composition as amount of hydrogen, methane and carbon dioxide. The distribution of the added metals between the liquid and solid phase has also been monitored. The results of our investigations show that the addition of any of the listed metals to the sludge may cause the production of a higher amount of biogas and influence the methane or carbon dioxide percentage. Conversely, the effect on the hydrogen production depends upon the metal added, the age of the active sludge used, and its adaptation to the susbtrate. As a general feature, during the acidogenesis phase, nickel reduces, while iron increases, the percentage of dihydrogen in the biogas, while cobalt has no influence.

A thermodynamic database for the Al–Co–Cr–Ni system is built via the Calphad method by extrapolating re-assessed ternary subsystems. A minimum number of quaternary parameters are included, which are optimized using experimental phase equilibrium data obtained by electron probe micro-analysis and x-ray diffraction analysis of NiCoCrAlY alloys spanning a wide compositional range, after annealing at 900 °C, 1100 °C and 1200 °C, and water quenching. These temperatures are relevant to oxidation and corrosion resistant MCrAlY coatings, where M corresponds to some combination of nickel and cobalt. Comparisons of calculated and measured phase compositions show excellent agreement for the β–γ equilibrium, and good agreement for three-phase β–γ–σ and β–γ–α equilibria. An extensive comparison with existing Ni-base databases (TCNI6, TTNI8, NIST) is presented in terms of phase compositions.

An anaerobic fixed film reactor was operated at temperatures between 49 and 55-degrees-C, as a thermophilic reactor using actual pharmaceutical wastewater, to observe the effects of temperature and cobalt addition on the performance of the reactor. The reactor was operated with a COD of 2500 mg L-1 at HRT of 4.7 days. COD, TVA, SS, VSS, NH4-N, PO4-P and SO4 were measured. The temperature of 54-degrees-C was found to be the optimum operating temperature with respect to the removal efficiency. Cobalt addition did not affect COD removal and increased gas production but decreased methane percentage.

Dicobalt edetate is one of a number of cobalt compounds that have been studied in the treatment of cyanide poisoning, their efficacy being based upon the fact that cyanide combines with cobalt to form relatively non-toxic complexes. Inorganic cobalt salts are quite toxic (cyanide and cobalt antagonise one another's toxicity) and complexes such as dicobalt edetate were studied with the aim of identifying compounds that were less acutely toxic, but which retained the antidotal properties of cobalt salts. The proprietary preparation, Kelocyanor™, contains free cobalt and glucose as well as dicobalt edetate.The aim of this study was to evaluate the published evidence for the efficacy and adverse effects of dicobalt edetate.A Pubmed search was undertaken for the period 1961-September 2015. The search terms were "dicobalt edetate", "cobalt edetate" and "Kelocyanor", which produced 24 relevant citations. A review of the references in four relevant books (L'intoxication cyanhydrique et son traitement, Clinical and Experimental Toxicology of Cyanides, Antidotes for Poisoning by Cyanide and Antidotes) produced three further relevant papers, making a total of 27 papers. Efficacy of dicobalt edetate: There is evidence from animal pharmacodynamic studies that dicobalt edetate is an effective cyanide antidote in experimental animals. Some 39 cases of human poisoning treated with dicobalt edetate have been reported, but in only nine cases were blood cyanide concentrations measured, although administration of dicobalt edetate procured survival in four of the seven patients with concentrations in the lethal range (3.0 mg/L). It is unlikely that death in any of the adequately documented fatal cases was attributable to treatment failure with dicobalt edetate, as it is probable that they all had suffered anoxic brain damage before treatment could be initiated. Furthermore, in one case, acute gold toxicity contributed substantially to death. Adverse effects of dicobalt edetate: Adverse effects reported have included hypertension, tachycardia, nausea, retrosternal pain, sweating, palpebral, facial and laryngeal oedema, vomiting, urticaria and/or a feeling of impending doom. Such effects appear to be more prevalent where the antidote has been administered without evidence of substantial systemic poisoning or where other antidotes have been used which might have been expected also to combine with cyanide. Although the adverse effects observed were doubtless unpleasant, and some were severe, no fatal reactions were found.Dicobalt edetate is an effective cyanide antidote when given to patients with systemic cyanide poisoning, but it has the potential to give rise to adverse reactions, particularly when administered in the absence of intoxication.

One in eight of all total hip replacements requires revision within 10 years, 60% because of wear-related complications. The bearing surfaces may be made of cobalt/chromium, stainless steel, ceramic, or polyethylene. Friction between bearing surfaces and corrosion of non-moving parts can result in increased local and systemic metal concentrations.To identify and systematically review published reports of systemic toxicity attributed to metal released from hip implants and to propose criteria for the assessment of these patients.Medline (from 1950) and Embase (from 1980) were searched to 28 February 2014 using the search terms (text/abstract) chrom* or cobalt* and [toxic* or intox* or poison* or adverse effect or complication] and [prosthes* or 'joint replacement' or hip or arthroplast*] and PubMed (all available years) was searched using the search term (("Chromium/adverse effects"[Mesh] OR "Chromium/poisoning"[Mesh] OR "Chromium/toxicity"[Mesh]) OR ("Cobalt/adverse effects"[Mesh] OR "Cobalt/poisoning"[Mesh] OR "Cobalt/toxicity"[Mesh])) AND ("Arthroplasty, Replacement, Hip"[Mesh] OR "Hip Prosthesis"[Mesh]). These searches identified 281 unique references, of which 23 contained original case data. Three further reports were identified from the bibliographies of these papers. As some cases were reported repeatedly the 26 papers described only 18 individual cases. Systemic toxicity. Ten of these eighteen patients had undergone revision from a ceramic-containing bearing to one containing a metal component. The other eight had metal-on-metal prostheses. Systemic toxicity was first manifest months and often several years after placement of the metal-containing joint. The reported systemic features fell into three main categories: neuro-ocular toxicity (14 patients), cardiotoxicity (11 patients) and thyroid toxicity (9 patients). Neurotoxicity was manifest as peripheral neuropathy (8 cases), sensorineural hearing loss (7) and cognitive decline (5); ocular toxicity presented as visual impairment (6). All these neurological features, except cognitive decline, have been associated with cobalt poisoning previously. Type of prosthesis and blood metal concentrations. Where blood or serum metal concentrations were reported (n = 17 for cobalt and n = 14 for chromium), the median cobalt concentration was 398 (range, 13.6-6521) μg/L and the median chromium concentration was 48 μg/L (in whole blood) (range, 4.1-221 μg/L including serum and blood values). Those patients reported to have systemic features who had received a metal-on-metal prosthesis (n = 8) had a median peak blood cobalt concentration of 34.5 (range, 13.6-398.6) μg/L; those with a metal-containing revision of a failed ceramic prosthesis (n = 10) had a median blood cobalt concentration of 506 (range, 353-6521) μg/L. Management. The most common treatment was removal of the metal-containing prosthesis, undertaken in all but 2 patients. This was usually associated with a fall in circulating cobalt concentration and improvement in some or all features. Clinical and toxicological assessment of systemic features. We propose the following criteria for assessing the likelihood that clinical features are related to cobalt toxicity: clinical effects consistent with the known neurological, cardiac, or thyroidal effects of cobalt, and for which any other explanation is less likely; increased blood cobalt concentrations (substantially higher than those in patients with well-functioning prostheses) several months after hip replacement; a fall in the blood cobalt concentration, usually accompanied by signs of improvement in features. When judged by these criteria, the systemic features in 10 of the reported cases are likely to be related to cobalt exposure from a metal-containing hip prosthesis.Rarely, patients exposed to high circulating concentrations of cobalt from failed hip replacements develop neurological damage, hypothyroidism and/or cardiomyopathy, which may not resolve completely even after removal of the prosthesis. The greatest risk of systemic cobalt toxicity seems to result from accelerated wear of a cobalt-containing revision of a failed ceramic prosthesis, rather than from primary failure of a metal-on-metal prosthesis.

This paper deals with the bonding of sulfur-vulcanized rubber compounds to metals. It had previously been reported that bis-(triethoxysilyl)ethane and vinyltriethoxysilane were found to work for bonding peroxide-cured rubber compounds to metals. These silanes were found not to work with sulfur-cured rubber compounds. In this case, a mixture of bis-(trimethoxysilylpropyl)amine and bis-(triethoxysilylpropyl) tetrasulfide was found to work and results are presented of experiments in which brass, steel, and electrogalvanized steel were bonded to a typical tire cord skim compound with and without a cobalt additive. This new silane treatment was found to be as effective as or better than brass adhesion to cobalt-containing rubber compounds. The superior corrosion protection offered by the silanes was also demonstrated using DC corrosion and polarization resistance measurements. The silane process reported in this paper behaves almost similarly with all metal substrates. In this paper, the structure of the silan...

In this paper, we present the synthesis of a Co–WC compound with 80% of cobalt in a single step by sintering powders compacted and previously milled for 10 h. The purpose of this work is to obtain ...

This paper explains and demonstrates the capabilities of Metal Additive Manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 Cobalt-Chromi...

This paper evaluates and demonstrates the methods for additively manufactured stent and the use of material ASTM F75 Cobalt-based superalloy (CoCrMo) by evaluating the chemical content, hot isostat...

This paper describes a study of the segregation process in which nickel, cobalt and iron are extracted as volatile metal chlorides from a limonite laterite and collected as ferronickel onto carbon ...

This paper explains and demonstrates the capabilities of metal additive manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 cobalt chromi...

This paper describes a detailed study of the segregation process in which nickel, cobalt and iron were extracted as volatile metal chlorides from a nontronite laterite, and concentrated as alloy on...

Extract In the last 2 years, two papers have been published suggesting that current New Zealand reference criteria for diagnosing cobalt deficiency should be reviewed (Grace et al 2003), and they are conservatively high and lead to the over-diagnosis of vitamin B12 deficiency and ill-thriftiness in sheep (Gruner et al 2004). The comments refer to reference ranges cited by animal health diagnostic laboratories. These reference ranges were derived from the paper by Clark et al (1989), which reviewed data from published and unpublished weight gain response trials preceding that date. The review included all published trials in New Zealand and as many unpublished trials that the authors could obtain. They involved serum vitamin B12 data from 54 trials and liver vitamin B12 data from 21 trials. It was stated that more data from trials conducted in autumn were required to reliably determine an autumn response curve. In addition, it was envisaged that as other trial data became available the reference c...

This paper discusses aquathermolysis process of heavy crude oil from Boca de Jaruco reservoir, which is developed by CSS method. The catalysts based on cobalt, nickel, iron and cupper are used to i...

This paper deals with the systematic investigation of microstructure, optical and magnetic properties of Co doped CaSnO3 nanostructures prepared by hydrothermal route. Detailed structural a...

Electropolishing is a common method for decreasing surface roughness and removing surface irregularities. In this paper the electropolishing of nickel and cobalt are successfully demonstrated in a deep eutectic solvent, comprising a 2:1 molar mixture of ethylene glycol and choline chloride. Voltammetric and electrochemical impedance studies were used to characterise the polishing mechanism and show that film formation occurs prior to polishing. Scanning electron microscopy and atomic force microscopy were used to characterise the morphology before and after polishing and 3D optical microscopy was used in-situ to observe film formation during polishing. This study shows that the impact of film formation and subsequently mass transport are responsible for electropolishing of both metals in the choline chloride-based ionic liquid.

In this paper, we elucidated the synthesis, characterization, and investigation of catalytic activity studies of new metallophthalocyanines 4 and 5 as the catalyst for phenolic compounds oxidation ...

The main limiting factor for P92 steel, in power plant at high temperature, is the increased oxidation damage on the inside surface which causes enhanced damage of components. Industry have attempted to address this problem by applying oxidation resistant coatings to the inside surface of the P92 pipework to prevent damage. Aluminide diffusion coatings have been a particular focus for research to date, however they have been found to have a number of detrimental effects on the creep properties and coating-substrate integrity. This paper introduces a Co-Cr-C type coating, composed of Cr3C2 particles electro-deposited within a cobalt matrix. On exposure to high temperature oxidation conditions the coating is shown to form a cobalt and chromium rich oxide which is slow growing, adherent and ideal for oxidation resistance. When applied to P92 substrate and exposed at service relevant temperatures the coated system retains its integrity and appears suitable for long term service. The coated P92 system ...

This paper describes a simple, rapid, inexpensive method for the preparation of a new biosorbent based on the modification of miswak fibers by NaOH (AT-Miswak-F). The synthesized AT-Miswak-F sorbent was utilized as an efficient sorbent for the extraction and preconcentration of iron group metal ions from various water samples. In this study, it was found that Fe(III), Co(II) and Ni(II) ions were completely extracted (100%) at pH range of 3–7 and flow rate of 0.3–2.0 mL min −1 . Also, the sorption capacity of AT-Miswak-F for Fe(III), Co(II) and Ni(II) are 0.54, 0.24 and 0.15 mmol g −1 , respectively. Equilibrium was best described by Freundlich isotherm model ( R 2 = 0.793) and the initial rate constants were 0.077, 0.054 and 0.035 mmol g −1 min −1 , respectively. Under the optimized conditions, the method exhibited a detection limit of 1.4, 2.8 and 2.1 ng mL −1 for Fe(III), Co(II) and Ni(II) ions in water samples with relative standard deviations of 2.6% ( n = 4). The method was successfully applied for the determination of Fe(III), Co(II) and Ni(II) ions in sea, ground and contaminated water samples.

In this paper, two average tungsten carbide particle sizes of 2, 0.5 μm are placed respectively, in contact with a WC-16Co substrate, pressed at the pressure of 4.5–5.5 GPa, and heated to temperatures ranging from 1350°C to 1500°C in a large-volume cubic press. During the process Co was forced out of the WC-16Co substrate into the compressed powder. The resulting infiltrated samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), Vickers hardness and cutting performance tests. The results of XRD confirmed that the sintered bulks have WC and Co phases. The scanning electron microscopy (SEM) analysis reveals that the WC grains in well-sintered alloys are round in shape and cobalt with lower content is uniformly dispersed in the WC grain boundaries. The sintered sub-micron WC-Co alloy with a cobalt content of 3.8 wt% exhibits a prominent combination of high hardness value of 23.1 GPa and a large fracture toughness value of 8.6 MPa m½. The high-speed cutting tests...

Cast ASTM F75 femoral knee implant components distort during manufacture due to residual stress re-distribution or inducement. These castings pose a number of challenges for residual stress determination methods; they have a complex geometry, their microstructure is inhomogeneous, they work-harden rapidly and they have a coarse, elastically anisotropic grain structure. The contour method is anticipated to be the most promising residual stress determination technique. X-ray diffraction is feasible for components which have experienced plastic deformation on their surface which results in refined diffracting domains. Centre-hole drilling is feasible, but the influence of stress induced from drilling and the effect of coarse grain structure is unknown. Neutron diffraction is challenging also due to a coarse grain structure and difficult nuclear material properties.This paper is part of a Themed Issue on Measurement, modelling and mitigation of residual stress.

In this paper, two novel metal-organic frameworks [Cu(bna1)(DMF)]n·nH2O·nCH3OH (complex 1) (H2bna1 = 2,2′-dihydroxy-1,1′-dinaphthyl-6,6′-dicarboxy acid) and [Co(bna2)2(bpy)(H2O)2]n (complex 2) (H2bna2 = 2,2′-dihydroxy-1,1′-Dinaphthyl-4,4′-dicar–boxyacid) have been synthesized under mild conditions and carefully characterized. Crystal structural analysis reveals that complex 1 adopts a 1D infinite chain structure, which forms 2D sheet by π–π weak interactions. Complex 2 possesses 2D sheet structure, where Cobalt ions are recognized as the nodes. So it generated a regular two-dimensional grid with the size of 1.57 × 1.15 nm. Complex 2 assembles into a 3D supramolecular network connected by the hydrogen bonds. IR spectra studies indicate that the coordination mode of carboxyl group of complex 1 and complex 2 are chelating with the metal ions. X-ray powder diffraction (PXRD) studies of both complexes confirm that there is no impurity phase in both complexes since their diffraction patterns match well with the...

Recent experimental observations show that twin boundaries in hexagonal close-packed (hcp) metals are frequently faceted. The objective of this paper is to investigate the influence of this faceting on the strain produced by twinning. We show that basal–prismatic (BP) facets are terminated by opposite disclinations and the migration of these facets along a straight twin boundary produces ordinary twinning shear. On the other hand, joining conjugate twins gives rise to BP facets terminated on the parent twin boundaries by identical disclinations. In this case, the strain produced by the migration of BP facets is an average between the strains produced by the individual conjugate twins. These theoretical studies are complemented by two EBSD measurements on cobalt that is closely related to magnesium. The misorientation profiles measured across two conjugate twin boundaries yield a misfit of approx. 7° consistent with the theoretical prediction that the corner of a twin embryo is terminated by two identical ...

Carbon-encapsulated cobalt nanoparticles (Co@C) are prepared by the chemical vapour deposition of methane at 773–1073 K. This paper investigates the graphitisation and microstructure transformation of Co@C governed by synthesis temperature. The results show that carbon shells consisting of amorphous carbon or small graphite fragments begin forming on Co nanoparticles from 773 to 873 K. The products transform into onion-like carbon-encapsulated cobalt nanoparticles at 973 K. At 1073 K, a higher graphitisation of Co@C is achieved, with the appearance of carbon nanotubes. With a rising synthesis temperature, the carbon shells undergo the transformations from amorphous carbon to graphite fragments and finally to onion-like carbon. The microstructural transformations are demonstrated by scanning electron microscope, transmission electron microscope and Raman characterisations. Therefore, controlling the synthesis temperature is a feasible and easy approach one can take to adjust the structure and graphitisatio...

This paper is meant to be a report on the experimental work on dilute Pd-based alloys with Co, Fe and Mn. These alloys exhibit the phenomenon of giant moments. The importance of measurements on paramagnetic alloys is emphasized. From these measurements the conclusion can be drawn that Co and Fe dissolved in Pd does not behave like a normal paramagnet, i.e. according to a Brillouin function. This result makes it possible to explain the existing discrepancy in the interpretations of magnetic measurements on one hand and of specific-heat experiments on the other. The main conclusions of this paper are: The giant moment should be accounted for by ‘normal’ values of the magnetic quantum number (3/2 for Co, 2 for Fe and 5/2 for Mn) and a large value of geff. Paramagnetic alloys of Mn in Pd behave according to Brillouin functions, but alloys of Co or Fe in Pd do not. Hence, a number of interpretations of magnetic measurements should be considered as incorrect. The localized model for ferromagnetism can ...

Degradation studies on a reactive dye Acid Red 1 are carried out by lignite fly ash (LFA) and cobalt-doped over LFA under UV-C radiation. In India, disposal of fly ash is a major problem. As fly ash is an inert material containing small quantities of photoreactive, inorganic oxides like TiO2, CaO and Fe2O3, this paper makes an effort to use it to overcome the degradation of dye and disposal of the fly ash problem. The chemical composition of LFA is analysed by X-ray fluorescence. Scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction are carried out to characterise the physical and photophysical properties of the catalyst. The optimum parameters affecting the dye degradation are found for LFA and cobalt-doped LFA under UV-C light. The kinetic coefficients for both catalysts are also determined. Cobalt-doped LFA proved the most effective, followed by LFA, and the corresponding efficiencies are 99 and 95%, respectively, at the end of 60 min. The reuse of cobalt-...

In this paper, we produced spinel structure nanometre cobalt blue powder pigment by chemical coprecipitation. We also modified it through element doping and analysed the spinel structure and colouring mechanism of the pigment. We discussed the process conditions of coprecipitation reaction, the influence of doping element and its content on the properties of cobalt blue pigments spectral reflection effect. The morphology and particle size of powders were characterised through scanning electron microscopy and energy dispersive spectroscopy. The doping element type and content have great influence on the spectral curve of the cobalt pigment. High temperature in sintering contributes to the performance of the products. The sample produced at 1250°C sintering possesses good reflection characteristics, which is similar to chlorophyll.

Complex perovskite materials are considered as a boon in this revolutionary era of microelectronic and telecommunications. In this paper we have presented the effect of replacement of Mg2+ by divalent ions (Co2+, Cu2+) in Ba(Mg0.33Nb0.67)O3. We have studied the impact of replacement of Mg2+ by transition elements on structural, micro-structure, dielectric properties. It is observed that on replacing the Mg2+ by Co2+ and Cu2+ the structural symmetry shifts from hexagonal (BMN, BCoN) to tetragonal (BCuN). Further, the morphological study reveals agglomerated grain formation for BCoN and a spikes/elongated type of structure in BCuN samples. The frequency dependence of dielectric studies shows the polar behavior of BMN. On the other hand replacing Mg by cobalt or copper (having 3d7 and 3d9 configuration, respectively), leads to Jahn-Teller distortions introduced in the samples. The poly-dispersive natures of the samples were inferred through fitting the curves with Cole–Cole equation.

The influence of cobalt (Co) on the as-cast microstructure of an Ni-based single crystal superalloy and its chemical segregation, incipient melting temperature and stress rupture properties was investigated. The results show that the dendrite arm spacing in the alloy did not vary with the addition of Co. The γ′ size in the as-cast microstructure decreased with increasing Co content. The segregation ratio of the γ′-forming elements titanium (Ti) and tantalum (Ta) became higher in alloys with high Co content (5%, 10%), while the segregation ratio of the γ-forming elements chromium (Cr) and molybdenum (Mo) first increased then decreased with increasing Co content, attaining the minimum around 10% Co. The incipient melt temperature decreased with increasing Co content. The stress rupture life under 1010°C/248 MPa increased with the increasing of Co content up to 10%, but decreased at 15% Co. The related mechanisms are also discussed in this paper.

In recent years, diluted magnetic oxides (DMOs) have been intensively studied aiming for using for spin injection and transportation. In this paper, DMOs of cobalt doped CeO2 (CCO) films with varied cobalt content (0–10%) were fabricated on Al2O3 (0001) substrates by both pulsed laser deposition (PLD) and magnetron sputtering respectively. Pulsed laser deposited and sputtered CCO films showed CeO2 (111) and (100) preferred orientations respectively. These two types of films with different crystallinity had almost the same magnetic and magneto-optical properties, such as room temperature ferromagnetism, non-linearly dependent of the moments on cobalt content, anisotropic magnetisation with an easy axis in out of plane direction and giant Faraday effect. The largest Faraday rotation value of ∼4500° cm−1 at 650 nm wavelength was obtained, for both PLD and magnetron sputtered films. The successful fabrication of ferromagnetic CCO films with controllable preferred orientations on Al2O3 (0001) substrates would ...

Tungsten is conventionally made by the reduction of tungsten oxide with hydrogen, tungsten carbide by the reaction of tungsten with carbon and cemented tungsten carbide by the sintering together of tungsten carbide with a metal, usually cobalt. This paper reports the electrochemical preparation of tungsten, tungsten carbide and cemented tungsten carbide starting with calcium tungstate, carbon and cobalt oxide, depending upon the desired end product. The starting materials were mixed and pelletised, and the pellets then made the cathode in a calcium chloride based melt. On the application of a modest potential (∼3 V), the calcium tungstate was reduced to tungsten, the mixture of calcium tungstate and carbon to nanosized tungsten carbide and the mixture of calcium tungstate, cobalt oxide and carbon to cemented tungsten carbide, all in ∼1 h. The products were characterised and the reaction path determined.

INTRODUCTION. There has been some recent concern regarding possible systemic health effects resulting from elevated blood cobalt concentrations in patients with cobalt containing hip implants. To date there are no blood cobalt criteria to help guide physicians when evaluating an individual hip implant patient's risk of developing systemic health effects because historically there was little or no concern about systemic cobalt toxicity in implant patients. OBJECTIVE. Our purpose is to describe recently completed research regarding the relationship between blood cobalt concentrations and clinical health effects. We discuss the possibility of systemic health effects in patients with metal containing implants and propose various blood cobalt concentrations that are not associated with an increased risk of developing certain adverse effects. METHODOLOGY. The primary literature search was conducted using PubMed and Web of Science using the following search terms: cobalt AND (toxicity OR health effects OR cardiotoxicity OR hematological OR endocrine OR immunological OR reproductive OR testicular effects OR neurological OR case report OR cohort OR Roncovite). The searches identified 6786 papers of which 122 were considered relevant. The Agency for Toxic Substances and Disease Registry toxicological profile for cobalt and the U.S. Environmental Protection Agency Office of Research and Development's National Center for Environmental Assessment's documentation on the provisional peer-reviewed toxicity value for cobalt were also utilized to identify secondary literature sources. RESULTS. Our review of the toxicology and medical literature indicates that highly elevated blood cobalt concentrations can result in certain endocrine, hematological, cardiovascular, and neurological effects in animals and/or humans. These studies, in addition to historical clinical findings involving the therapeutic use of cobalt, indicate that significant systemic effects of cobalt will not occur below blood cobalt concentrations of 300 μg/L in most persons. Some individuals with specific risk factors for increased susceptibility (e.g., severe and sustained hypoalbuminemia) may exhibit systemic effects at lower cobalt blood concentrations. This review also describes several cobalt dosing studies performed with human volunteers that consumed cobalt for 15, 30, or 90 days. Overall, the results of these dosing studies indicate that sustained blood cobalt concentrations averaging 10-70 μg/L for up to 90 days cause no significant clinical effects (maximum concentrations approached 120 μg/L). Some proposed blood criteria for assessing implant wear and local tissue damage have been suggested by several medical groups. For example, the UK Medicines and Healthcare Products Regulatory Agency has proposed a blood cobalt guidance value of 7 μg/L, and the Mayo Clinic has suggested serum cobalt concentrations greater than 10 μg/L, but both of these values are primarily intended to address implant wear and to alert physicians to the possibility of an increased incidence of local effects. There is a clear lack of consensus regarding how to identify a specific numerical blood concentration of concern and whether whole blood or serum is a better matrix to assess total cobalt concentration. CONCLUSIONS. Based on currently available data, only under very unusual circumstances should a clinician expect that biologically important systemic adverse effects might occur in implant patients with blood cobalt concentrations less than 300 μg/L. Patients with metal-containing hip implants who exhibit signs or symptoms potentially related to polycythemia, hypothyroidism, neurological, or cardiac dysfunction should be clinically evaluated for these conditions. Polycythemia appears to be the most sensitive endpoint.

Cobalt (Co) is an essential element with ubiquitous dietary exposure and possible incremental exposure due to dietary supplements, occupation and medical devices. Adverse health effects, such as cardiomyopathy and vision or hearing impairment, were reported at peak blood Co concentrations typically over 700 µg/L (8-40 weeks), while reversible hypothyroidism and polycythemia were reported in humans at ~300 µg/L and higher (≥2 weeks). Lung cancer risks associated with certain inhalation exposures have not been observed following Co ingestion and Co alloy implants. The mode of action for systemic toxicity relates directly to free Co(II) ion interactions with various receptors, ion channels and biomolecules resulting in generally reversible effects. Certain dose-response anomalies for Co toxicity likely relate to rare disease states known to reduce systemic Co(II)-ion binding to blood proteins. Based on the available information, most people with clearly elevated serum Co, like supplement users and hip implant patients, have >90% of Co as albumin-bound, with considerable excess binding capacity to sequester Co(II) ions. This paper reviews the scientific literature regarding the chemistry, pharmacokinetics and systemic toxicology of Co, and the likely role of free Co(II) ions to explain dose-response relationships. Based on currently available data, it might be useful to monitor implant patients for signs of hypothyroidism and polycythemia starting at blood or serum Co concentrations above 100 µg/L. This concentration is derived by applying an uncertainty factor of 3 to the 300 µg/L point of departure and this should adequately account for the fact that persons in the various studies were exposed for less than one year. A higher uncertainty factor could be warranted but Co has a relatively fast elimination, and many of the populations studied were of children and those with kidney problems. Closer follow-up of patients who also exhibit chronic disease states leading to clinically important hypoalbuminemia and/or severe ischemia modified albumin (IMA) elevations should be considered.

CoWP alloy films were prepared by a typical citrate system electrodeposition on a copper substrate. The paper investigated effects of different temperatures on codeposition mechanism, magnetic property, component and structure of CoWP alloy films during the electrodeposition process. With the increase in temperatures, deposition rate and thickness rose gradually during the electrodeposition process. It was found that higher temperature improved contents of phosphorus and tungsten but reduced amounts of cobalt in the films. Almost all the deposited films were crystalline and formed tetrahedral structures Co3W with preferred crystallographic orientation (200) and (201). Films of dissimilar surface morphology could be observed under different temperatures. Lower saturation magnetisation and higher coercivity of CoWP films could be obtained at higher temperatures.

Inhomogeneity in the particle size of the tungsten carbide raw material can result in abnormal WC grain growth in WC–Co cemented carbides. For the preparation of ultrafine tungsten carbide powders and ultrafine cemented carbides, abnormal WC grain growth is the most troublesome issue. This paper deals with the effects of cobalt additions on WC grain growth during the carburisation process of nano- and coarse tungsten powders and the sintering process of ultrafine tungsten carbide powders. For the preparation of tungsten carbide powders, it was shown that through the incorporation of 0·035 wt-%Co into W+C mixtures, a dramatic change in WC grain morphology took place for coarse tungsten raw material, while for nanotungsten raw material, a pronounced WC grain growth took place. Plate-like truncated trigonal and hexagonal WC grains were formed during the carburisation process of coarse tungsten raw material containing 0·035 wt-%Co. For the sintering of ultrafine tungsten carbide powders containing 0·3...

This paper aims to compare the behaviour of cobalt and iron base hardfacing alloys on hot forging dies under temper, shock and wear. Tempering resistance, shocking behaviour and wear resistance were investigated using a tubular furnace, press and pin on disc tribometer respectively. The results showed that the thermal stability of commercial iron base hardfacing alloy (named RMD248) is good below 550°C but poor in the case of higher temperature, whereas the cobalt base hardfacing alloy presents superior tempering resistance. The cobalt base hardfacing alloy possesses excellent shock hardening properties at all the experimental temperatures, but RMD248 does not, especially at high temperature (600°C). Compared with the hardfacing layer produced by RMD248, the cobalt base hardfacing layer produces high wear resistance at 600°C and high temperature oxidation resistance at 600°C for 100 h.

In this paper, we report the degradation behavior of a LDPE-grafted Maleic anhydride polymer prepared using a reactive extrusion technique. 70 ± 5 µm blown films were exposed to oxidative environments, and the degradation was followed by monitoring physico-chemical and morphological changes. The studies indicated that grafting with Maleic anhydride does not affect the degradation characteristics of the base polymer. Kinetic parameters of degradation, as estimated using non-isothermal TGA, were used to estimate the theoretical lifetime of the polymers, which remained unaltered due to grafting. The results, however, indicated that cobalt stearate, a typical pro-oxidant, led to massive degradation during thermal processing.

The effect of Fe3+ ions substitution by rare earth La3+ ions on magnetic properties of nano crystalline cobalt ferrite is investigated and reported in this paper. Co-precipitation method was used to prepare ultrafine particles of CoLaxFe2-xO4 (x = 0, 0.10, 0.15). The samples have cubic spinel structure and average crystallite size of x = 0, x = 0.1 and x = 0.15 are 49.84 nm, 27.73 nm and 47.97 nm respectively. Structure has been investigated by XRD and TEM while magnetic properties have been studied using VSM and Mossbauer spectrometer. La3+ ions modulate significantly the magnetic properties of cobalt spinel ferrites.

Electroless plating have unique metallurgical characteristics, and the deposits can be made onto a wide range of substrates, including both metallic and non‐metallic surfaces. In this paper, the authors have reported on the development of new bath formulation for getting Ni–Co–P nanoalloy deposit and optimised bath concentration and operating conditions. The alloy deposit contains 10·59%Co in the Ni–P matrix. There is an increase in hardness and corrosion resistance of the deposit with the incorporation of Co. Furthermore, from the XRD measurements of the deposits, it was found that the alloy is nanocrystalline in nature, and the particle size is around 37–45 nm. Atomic force microscopy results show that the height of the particles is in nanosize, and roughness of the surface is within 3 nm.

The feasibility of using ion-exchange resins to separate cobalt and antimony from zirconium in acid solutions was investigated. The distribution coefficients of zirconium, cobalt, and antimony on strong cation and anion exchangers in HCl and oxalic acid media were determined. The mass effect of zirconium on the distribution coefficients of cobalt and antimony was studied. The isotherm for zirconium was obtained in HCl solution. The distribution coefficient and isotherm data were used to develop ion-exchange processes for separation of cobalt and antimony from zirconium in the linear and nonlinear regions of the isotherm. A decontamination factor of more than 10 3 was achieved in a single ion-exchange cycle with respect to both cobalt and antimony. Two cycles of ion exchange will bring down the activity to acceptable levels for processing of irradiated zirconium as well as achieve a significant reduction in the waste volume. This is the first paper on separation of 60 Co and 125 Sb from zirconium for radioactive waste management.

The aim of this paper was to investigate the effect of increasing cobalt content on the corrosion resistance of the Fe-Co-Cr-B-Si alloys in dilute mineral acids. The corrosion rates in 0.5N HCl, 1N HCl and 1N H2SO4 significantly decrease with an increase in Co content. The high corrosion resistance of the Fe-Co-Cr-B-Si alloys is also due to the formation of a chromium-enriched passive film. Generally, the corrosion resistance of chromium-bearing alloy is improved by alloying with various metalloids but it is lowered by the addition of boron and silicon. The corrosion behaviour of the amorphous Fe75-xCoxCr1B7Si17 (where: x=1, 4, 7 and 10 at. % Co) alloys obtained by the melt-spinning technique was studied using the gravimetric method. The best results were obtained with Fe65Co10Cr1B7Si17 alloy.The studied amorphous alloy ribbons exhibit not only excellent physical properties which are useful for many electric and magnetic applications such as magnetic sensors, power transformers, etc., but also a v...

Highly dispersed, oxide- or zeolite-supported bimetallic catalysts are widely used in the catalytic industry, such as in catalytic reforming, nitrogen industry and gas-to-liquid technology. The paper highlights the nano-sized Co-based bimetallic system in terms of correlation between structure and reactivity/selectivity promoted by the second metal. Opposite to the bulk alloys nano-sized bimetallic catalysts are extremely sensitive to the structure, morphology, valence state of the supporting oxide material in which the nano-particles are embedded. In this case, one of the less reducible components, which strongly interact with the supports, may stabilize the second, more noble metals, and thus the latter can be stabilized in highly dispersed state. Conversely, addition of noble metal to the hardly reducible component may facilitate reduction, which causes the retardation of the deactivation process of some hydrocarbon reaction. The future trend is the application of bimetallic nano-particles although car...

The presence of heavy metals in aqueous solutions beyond certain limits creates serious threat to the environment due to their non-degradability and toxicity. So the search for techniques to remove those pollutants is of increasing interest. Liquid membranes have shown great potential in this way, especially in cases where pollutant concentrations are relatively low and other techniques cannot be applied efficiently. A kinetic study of the influence of some operational variables (organic phase volume, emulsifier concentration in the membrane phase and stirring rate) on the transport of cobalt (II) through bulk liquid membrane containing di(2-ethylhexyl) phosphoric acid (D2EHPA), as mobile carrier, in kerosene and protons, as counter ions, in the product phase (H2SO4), is carried out is this paper. The transport kinetic was analysed by means of a kinetic model involving two consecutive irreversible first order reactions. The rate constants of the extraction and stripping reactions were determined for all t...

A review of the literature dealing with the effect of cobalt on lead-based anodes for oxygen evolution during electrolysis of sulfuric acid solutions verifies that the presence of cobalt at the anode–electrolyte interface, either as constituent of the anode material or as ions in the electrolyte, catalyzes the evolution of oxygen and reduces the corrosion of the anodes and the contamination by lead of metal cathodes produced during electrowinning. However, due to harmful effects of cobalt ions on the cathodic reaction in some processes, these benefits are limited to the electrowinning of copper. Efforts to develop a way of introducing cobalt at the anode–electrolyte interface without interfering with the cathodic reactions are reviewed in this paper. The use of lead–cobalt alloy anodes has had limited success due to issues arising from the low solubility of cobalt in lead, segregation during casting of the alloys, and nonuniform distribution of cobalt which affects the integrity of the anodes. This has be...

The present paper describes Raman studies of chemically synthesized nanocrystalline cobalt-substituted (up to 10%) ZnO samples exhibiting room temperature ferromagnetism. These studies were carried out using Laser excitation wavelengths −457.9, 532 and 785 nm. The Raman spectra of the samples excited with 457.9 nm show predominantly lattice modes of ZnO because of pre-resonance enhancement. In the Raman spectra of cobalt added ZnO samples excited with 532 and 785 nm, clear evidence is seen for the presence of Co3O4 (an impurity phase not detectable in XRD) in the samples with cobalt exceeding 3%. The presence of Co3O4 in the samples having higher concentration of cobalt explains the nonmonotonic increase in magnetization with Co-concentration in the ZnO1 − xCox samples.

Electroforming, as a versatile process for fabrication of durable tools, is experiencing an increasing interest with the start of commercial use of products with micro or nanofeatures. Electroformed tools can be utilised for polymer, glass and metal replication processes and, in addition, when extreme demands, in terms of tool accuracy, process temperature and tool wear, are requested. In order to meet these demands, electroforming of hard nickel alloys is an obvious way forward. This paper presents several electrolytes from which it is possible to deposit nickel–cobalt alloys with high hardness (>550 HV), low internal stress and easy maintenance. Moreover, different organic complexing agents – as well as alternatives to boric acid – have been investigated.