Cobalt

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35-65% cobalt, 20-30% chromium, 0-30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (±S.D.) CB-MN frequencies (‰) in peripheral lymphocytes were 4.00 (±2.98) among the dental technicians and 1.40 (±1.30) among the controls, a statistically significant difference (P < 0.005). The mean (±S.D.) MN frequencies (‰) in nasal cells were 3.50 (±1.80) among the dental technicians and 1.19 (±0.53) among the controls, which was also a statistically significant difference (P < 0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r = 0.642, P < 0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.

Synthesis and characterization of [o-carboxy phenylazo] moiety of barbituric acid, thiobarbituric acid, thiouracil, citrazinic acid, and disodium chromotropate and their complexes derived from cobalt (II), nickel (II), and copper (II) salts were done. The stereochemistry and the mode of bonding of the complexes were achieved based on elemental analysis, NMR, UV-Vis, IR and ESR. The dissociation constants of the free azo ligands are evaluated by spectrophotometric methods.

A novel fluorometricmethod has been developed to evaluate hydroxyl radical prevention capacity using fluorescein (FL) as the probe. The hydroxyl radical is generated by a Co(II)-mediated Fentonlike reaction, and the hydroxyl radical formation under the experimental condition is indirectly confirmed by the hydroxylation of p-hydroxybenzoic acid. The fluorescence decay curve of FL is monitored in the absence or presence of antioxidant, the area under the fluorescence decay curve (AUC) is integrated, and the net AUC, which is an index of the hydroxyl radical prevention capacity, is calculated by subtracting the AUC of the blank from that of the antioxidant. Gallic acid is chosen as a reference standard, and the activity of sample is expressed as gallic acid equivalents. The method is rigorously validated through linearity, precision, accuracy, and ruggedness. A wide range of phenolic antioxidants is analyzed, and the hydroxyl radical prevention capacity is mainly due to the metal-chelating capability of the compounds.

A method for the determination of Fe(III), Co(II) and Cr(III) by flame atomic absorption spectrophotometry (FAAS) after preconcentrating on a column containing S. carlsbergensis immobilized on Amberlite XAD-4 has been developed. The optimum values of pH, amount of adsorbent, elution solution and flow rate of the sample solution were determined for the quantitative recovery of the analytes. The effect of interfering ions on the recovery of the analytes was also investigated. Under the optimum conditions, recoveries of Fe(III), Co(II) and Cr(III) by S. carlsbergensis immobilized on Amberlite XAD-4 were 99 AE 2, 100 AE 2 and 98 AE 2% at 95% confidence level, respectively. The limit of detections for Fe(III), Co(II) and Cr(III) were 2.8, 3.9 and 7.4 ng mL À1 , respectively. The proposed method was applied to the determination of the analytes in various water samples. The validity of the method was checked with spiked water samples. Fe(III), Co(II) and Cr(III) was determined with a relative error of less than 5%.

Current trends in transport electrification and mobile technologies have created an increasing demand for raw materials needed for battery production. The supply chains involved are global, complex, non-transparent and sometimes associated with unsustainable production practices. To improve on the current situation, it is essential to trace battery raw materials back to their origins to verify the conditions in which they were produced. This demand for increased transparency has triggered actions in European Union legislation and among companies operating within battery supply chains.

In this report, we review the current landscape for the application of traceability methods to battery supply chains. The report begins with a global overview of selected battery metals and minerals and their related sustainability issues. As sustainability is an integral goal for traceability, sustainability reporting systems for mining are reviewed from the perspective of traceability. Existing traceability methods and case studies in battery supply chains are reviewed, including the geo-based fingerprinting method (laboratory technology) that is being developed in the BATTRACE research project. We also discuss the business potential of the geo-based fingerprinting method.

Several drivers are identified for traceability. The main driver comes from regulatory development, such as the EU’s battery directives. Customer awareness of sustainability issues is also beginning to influence manufacturers (OEMs) to invest in the transparency of their battery metal supply chains. In addition, the producers of sustainable and low emission raw materials have identified the commercial benefit of tracing the greenhouse gas emissions of their products along the supply chain. Current sustainability and reporting systems used within the mining industry are inadequate to comply with the increased traceability needs, as their focus is limited to the beginning of the supply chain.

The traceability pilots that are currently in use are still limited in scope. For traceability to become commonplace in mining supply chains, OEMs will need to recognize the overall commercial benefits of traceability. Ethical questions dominate in the sustainability considerations on cobalt production, and there are indications that the cobalt market may be separating into traceable and certified cobalt, and bulk cobalt. For lithium and graphite production, the dominating sustainability considerations relate to water and energy consumption and dust. Lithium and graphite are not currently communicated to be included in any digital traceability solution under preparation, but they have been included in BATTRACE research for the geo-based fingerprinting method. Geo-based fingerprinting has considerable commercial potential as a traceability method and a verification tool. As the geological and elemental characteristics of a sample cannot be falsified, the method has unique potential as a stand-alone traceability technology, or as a complementary verification method with any other traceability system. The method could also serve as a verification tool in the “Metals from Finland” certificate, which could sharpen the marketing of sustainable and traceable battery metals production from Finland.

Dendritic cells (DCs) play a major role in the regulation of immune responses to a variety of antigens (Ag) and haptens which participate in the process of DC maturation. Indeed, metallic haptens are able to induce DC maturation in vitro but the mechanism of this maturation is not well understood. We and others have already shown that NiSO 4 activates p38 mitogen-activated protein kinases (p38MAPK), c-jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and the transcription factor NF-jB during the early events of DCs maturation. However, the effect of other metallic haptens on DC maturation is still poorly understood. In the present study, using dendritic cells derived from CD34 + cord blood cells, we showed that both NiSO 4 and CoCl 2 induced the expression of CD86, CD83, HLA-DR and CD40 and the production of IL-6 in human DCs while K 2 Cr 2 O 7 induced only a slight upregulation of CD86. Interestingly, only NiSO 4 was able to induce the production of IL-12p40. NiSO 4 and CoCl 2 but not K 2 Cr 2 O 7 were able to activate the MAPK pathway and the transcription factor NF-jB. The role of MAPKs in metals-induced DC maturation was then evaluated using well-described pharmacological inhibitors. Our results suggest that p38MAPK activation regulates the expression of CD86 and CD83 induced by NiSO 4 while it only affects the expression of CD83 induced by CoCl 2. IL-6 production induced by NiSO 4 and CoCl 2 strongly depended on all MAPKs. IL-12p40 synthesis after NiSO 4 treatment was regulated by both p38MAPK and JNK pathways whereas ERK may play an inhibitory role. Our results show that both NiSO 4 and CoCl 2 activate similar signaling pathways that are playing different roles in DC maturation depending on the hapten used.

Temperature dependencies of thermal expansion coefficients for the alloys of Pd-Ag, Pd-Cu and Pd-Co binary systems were measured at temperatures up to 900•Ž, with heating and cooling rates of 5•Ž/min. The coefficient of thermal expansion of alloys with no transformation in the temperature range of interest in porcelain firing was well approximated by a linear equation of temperature. The constants in the equation were shown as a function of the weight for the added element. Thermal expansion of the palladium-based alloy with no transformation was well estimated at any temperature range and at any composition by using the constants represented here. The coefficients of thermal expansion before and after order-disorder transformation and magnetic transformation were measured in Pd-Cu and Pd-Co alloys, respectively. The results suggest that transient and residual stresses in porcelain-fused-to-metal restorations can be effectively controlled by making use of transformation of the alloy.

Magnetic nanocomposite materials consisting of 5.5 wt% Fe-Co alloy nanoparticles in a silica aerogel matrix, with compositions Fe x Co 1Ϫx of x ϭ 0.50 and 0.67, have been synthesized by the sol-gel method. The high-resolution transmission electron microscopy images show nanoparticles consisting of single crystal grains of body-centered cubic Fe-Co alloy, with typical crystal grain diameters of approximately 4 and 7 nm for Fe 0.5 Co 0.5 and Fe 0.67 Co 0.33 samples, respectively. The energy dispersive X-ray~EDX! spectra summed over areas of the samples gave compositions Fe x Co 1Ϫx with x ϭ 0.48 6 0.06 and 0.68 6 0.05. The EDX spectra obtained with the 1.5 nm probe positioned at the centers of ;20 nanoparticles gave slightly lower concentrations of Fe, with means of^x& ϭ 0.43 6 0.01 and^x& ϭ 0.64 6 0.02, respectively. The Fe 0.5 Co 0.5 sample was studied using electron energy loss spectroscopy~EELS!, and EELS spectra summed over whole nanoparticles gave x ϭ 0.47 6 0.06. The EELS spectra from analysis profiles of nanoparticles show a distribution of Fe and Co that is homogeneous, i.e., x ϭ 0.5, within a precision of at best 60.05 in x and 60.4 nm in position. The present microscopy results have not shown the presence of a thin layer of iron oxide, but this might be at the limit of detectability of the methods.

With a model invertebrate animal we have assessed the fate of magnetic nanoparticles in biologically relevant media, i.e. digestive juices. The toxic potential and the internalisation of such nanoparticles by non-target cells was also examined. The aim of this study was to provide experimental evidence on the formation of Co 2+ , Fe 2+ and Fe 3+ ions from CoFe 2 O 4 nanoparticles in the digestive juices of a model organism. Standard toxicological parameters were observed. Cell membrane stability was tested with a modified method for assessment of cell membrane stability. Proton induced x-ray emission and low energy synchrotron radiation X-ray fluorescence was used to study internalisation and distribution of Co and Fe. Co 2+ ions were found to be more toxic than nanoparticles. We confirmed that Co 2+ ions are accumulated in the hepatopancreas but Fe n+ ions or CoFe 2 O 4 nanoparticles are not retained in vivo. A model biological system with a terrestrial isopod is suited to studies of the potential dissolution of ions and other products from metal-containing nanoparticles in biologically complex media.

The ␤-cyclodextrin (␤-CD) polyiodide inclusion complex (␤-CD) 2 •Co 0.5 •I 7 •21H 2 O has been synthesized, characterized and further investigated via FT-Raman spectroscopy in the temperature range of 30-120 • C. The experimental results point to the coexistence of I − 7 units (I 2 •I − 3 •I 2) that seem not to interact with the Co 2+ ions and I − 7 units that display such interactions. The former units exhibit a disorder-order transition of both their I 2 molecules above 60 • C due to a symmetric charge-transfer interaction with the central I − 3 [I 2 ← I − 3 → I 2 ], whereas in the latter units only one of the two I 2 molecules becomes well-ordered above 30 • C. The other I 2 molecule remains disordered presenting no charge-transfer phenomena. The Co 2+ ion induces a considerable asymmetry on the geometry of the I − 3 anion and a significant modification of its Lewis base character. Complementary dielectric measurements suggest no important involvement of H•••I contacts in the observed modification of the I − 3 electron-transfer properties.

A novel fluorometricmethod has been developed to evaluate hydroxyl radical prevention capacity using fluorescein (FL) as the probe. The hydroxyl radical is generated by a Co(II)-mediated Fentonlike reaction, and the hydroxyl radical formation under the experimental condition is indirectly confirmed by the hydroxylation of p-hydroxybenzoic acid. The fluorescence decay curve of FL is monitored in the absence or presence of antioxidant, the area under the fluorescence decay curve (AUC) is integrated, and the net AUC, which is an index of the hydroxyl radical prevention capacity, is calculated by subtracting the AUC of the blank from that of the antioxidant. Gallic acid is chosen as a reference standard, and the activity of sample is expressed as gallic acid equivalents. The method is rigorously validated through linearity, precision, accuracy, and ruggedness. A wide range of phenolic antioxidants is analyzed, and the hydroxyl radical prevention capacity is mainly due to the metal-chelating capability of the compounds.

The present business-as-usual cobalt use in society is not sustainable. Too much cobalt is lost if only market mechanisms are expected to improve recycling, and unnecessary cobalt is wasted if no policy actions are taken. Increased recycling and better conservation will be able to improve the supply situation, but this will need active policy participation beyond what market mechanisms can do alone. To conserve cobalt for coming generations, present policies must be changed within the next few decades. The sooner policies change, the better for future generations.

Chromium (Cr) and cobalt (Co) metal ions released from orthopedic prostheses, such as metal-on-metal (MoM) bearings, may be related to wear of the bearing surface. These ions may serve as indicators of the in vivo performance of MoM bearing surfaces. We developed a simple and sensitive assay suitable for the simultaneous measurement of serum Cr and Co using inductively coupled plasma-mass spectrometry (ICP-MS) in clinical routine laboratory practice to evaluate analytical performance and clinical utility. We evaluated the linearity, precision, and lower limit of quantification (LOQ) of an ICP-MS method to determine serum Cr and Co concentration in accordance with U.S. Food and Drug Administration guidance for bioanalytical method validation. This method was used to determine the serum Cr and Co levels of 236 clinical samples from 74 patients with MoM hip prosthesis and 51 healthy controls. The assay showed good linearity (0-20 μg/l, r(2)&gt;0.999) and satisfactory accuracy for all t...

A colloidal seeded-growth strategy, relying on time-programmed delivery of selected stabilizing surfactants, has been developed to synthesize bimagnetic hybrid nanocrystals (HNCs) that consist of a single-crystal tetrapod-shaped skeleton of ferrimagnetic (FiM) iron oxide functionalized with multiple polycrystalline spherical domains of ferromagnetic (FM) Co. Due to the direct bonding interfaces formed between the two materials at the relevant junction regions, the HNCs exhibit FiM-FM exchange coupling, which transcribes into a rich scenario of significantly modified properties (not otherwise achievable with any of the single components or with their physical mixtures), including higher saturation magnetization and coercitivity values, exchange biasing, and enhanced thermal stability due to induced extra anisotropy. The availability of these new types of HNCs suggests that development of appropriate synthetic tools for arranging distinct material domains in predetermined spatial arrangements could lead to a more rational design of nanoheterostructures potentially exploitable as active elements in future generations of magnetic recording devices.

4-(1H-Pyrazolo {3,4-d} pyrimidin-4-ylazo) benzene-1,3-diol was synthesized and characterized by various spectral and analytical techniques. Semiempirical quantum calculations using the AM1 method have been performed in order to evaluate the geometry and electronic structure of the title azodye in the ground state. The complex formation between Co(II), Ni(II) and Cu(II) ions and the title azodye was studied conductometrically and spectrophotometrically. The

OBJECTIVE To compare the levels of trace elements and heavy metal in patients with acute migraine and healthy controls. METHODS The prospective study was conducted at Yuzuncu Yil University, Turkey, from May to July 2013, and comprised migraine patients and an equal number of healthy controls. International Headache Society classification was used for diagnosing migraine. Serum copper, zinc, lead, iron, cadmium, cobalt, manganese, and magnesium levels were measured in both groups. Metal concentrations were assessed by atomic absorption spectrophotometry. SPSS 13 was used for statistical analysis. RESULTS There were 25 migraine patients with an average age of 36.4±8.9 years and 25 healthy controls with a mean age of 42.4±9.5 years. Cadmium, iron, manganese and lead levels were significantly elevated in the patients compared to the controls (p&lt;0.05 each), while copper, magnesium and zinc were decreased and cobalt demonstrated no change. CONCLUSIONS Trace elements and heavy metals m...

An electrochemical sensor for selective detection of ascorbic acid (AA) in the presence of dopamine (DA) and uric acid (UA) was fabricated by modifying the glassy carbon electrode (GCE) with carbon-supported NiCoO 2 (NiCoO 2 /C) nanoparticles. The electrochemical impedance spectroscopic (EIS) studies reveal the little charge transfer resistance for the modified electrode. The electrocatalytic activity of the modified electrode for the oxidation of AA was investigated. The current sensitivity of AA was enhanced to about five times upon modification. The voltammetric response of AA was well resolved from the responses of DA and UA, and the oxidation potential of AA was negatively shifted to À 0.20 V. The biosensor tolerated a wide linear concentration range for AA, from 1.0 Â 10 À 5 M to 2.63 Â 10 À 3 M (R 2 ¼0.9929), with a detection limit of 0.5 μM (S/N¼ 3). Our results demonstrate that the NiCoO 2 /C nanomaterials has excellent AA sensing capability, including a fast response time, high reproducibility and stability, with great promise in the quantification of AA in real samples. That makes it a unique electrochemical sensor for the detection of AA which is free from the interference of DA, UA and other interferents.

The creation of polymers with a high degree of sequence and/or stereocontrol represents an exciting frontier in materials science. In order to obtain alternating polymers, coordination polymerization using well-defined metal complexes has played a leading role in the last two decades. In the following paper, we will describe selected published efforts to achieve these research goals using discrete, structurally well-characterized metal complexes.

Bacterial strains from inoculated soybean field soil in Thailand were directly isolated using Bradyrhizobium japonicum selective medium (BJSM), on the basis of Zn 2+ and Co 2+ resistance of B. japonicum and B. elkanii. The isolates were classified into symbiotic and non-symbiotic groups by inoculation assays and Southern hybridization of nod and nif genes. In this study, a nearly full-length 16S rRNA gene sequence showed that the non-symbiotic isolates were more closely related to members of Rhodopseudomonas and to a number of uncultured bacterial clones than to members of Bradyrhizobium. Therefore, a polyphasic study was performed to determine the taxonomic positions of four representatives of the non-symbiotic isolates. Multilocus phylogenetic analysis of individual genes and a combination of the 16S rRNA and three housekeeping genes (atpD, recA and glnII) supported the placement of the non-symbiotic isolates in a different genus. The ability of heavy metal resistance in conjunction with phenotypic analyses, including cellular fatty acid content and biochemical characteristics, showed that the non-symbiotic isolates were differentiated from the other related genera in the family Bradyrhizobiaceae. Therefore, the nonsymbiotic isolates represented a novel genus and species, for which the name Metalliresistens boonkerdii gen. nov., sp. nov. is proposed. The type strain is NS23 (= NBRC 106595 T = BCC 40155 T).

In the electrodeposition system, adding saccharin alters the properties of the metal deposits by changing the electrode kinetics of the deposited surface. In this study, nanocrystalline cobalt-iron (CoFe) coating was synthesised using the electrodeposition technique with different saccharin concentrations. The results obtained showed that the coating thickness increased while the grain size decreased from 51 nm to 40 nm when the saccharin concentration increased from 0 to 2 g/L. The nanocrystalline CoFe coating produced with 2 g/L of saccharin concentration resulted in the smallest particle size of 71.22 nm and the highest microhardness of 251.86 HV. From the salt spray test (24 and 48 hours) it was found that the use of saccharin at higher concentration of 2 g/L improves the corrosion resistance of the nanocrystalline CoFe coating significantly due to the change of surface morphology as well as the decrease in grain size.

The nature of the bonding interactions in individual isomeric structures of the above carbonyls was studied using the analysis of domain averaged Fermi holes (DAFH). The main focus was directed on the confrontation of the picture of the bonding resulting from this analysis with the predictions of empirical 18-electron rule. This rule assumes, namely, the presence of direct metal-metal bond(s) for both carbonyls, but the detailed insights provided by the DAFH analysis show that the straightforward association of metal-metal bond with the favorable electron count only is too simplistic, and provided the actual structure of individual isomeric species is not taken into account, the predictions of this rule may fail. This is, e.g., the case of the C 2V isomer of the carbonylate anion [Fe 2 (CO) 8 ] 2where the DAFH analysis denies the existence of direct metal-metal bond similarly as in the case the isoelectronic Co 2 (CO) 8 . Similar discrepancies between the predictions of the 18-electron rule and DAFH analysis were found also in the case of the C 2V isomer of the neutral Fe 2 (CO) 8 carbonyl, where the DAFH analysis detects the presence of a single bent Fe-Fe bond rather than the double bond anticipated by the 18-electron rule.

Vitamin B 12 plays a key role in many metabolic processes occurring in all mammals. Over the years its biological role has been extensively studied generating a lot of interest in the chemistry of this vital molecule. This established a variety of new methodologies for the synthesis and analysis of new cobalamin derivatives as well as creative purification techniques. This tutorial review summarizes all the advancements made in this area, providing a deeper insight into vitamin B 12 chemistry. Key learning points -The nomenclature of corrinoids. -The chemistry of vitamin B 12 . -Selective modifications of cobalamin. -Purification and analysis of cobalamin and its derivatives.

The KU Leuven Dayr al-Barsha project worked in al-Shaykh Sa'id, just north of Amarna, in 2007-2010 and 2014, and discovered on the hillside, north of the mouth of the Wadi Zabayda, archaeological remains of a royal domain, dating to the reign of Khufu. Afterwards, royal workshops were established on top of the Old Kingdom remains to supply the New Kingdom city of Amarna with a range of different goods. Due to severe erosion, hardly any traces of buildings survive, but the industrial waste left behind provide sufficient clues that besides a vast stone artefact industry, the artisans were also making objects in faience, glass and copper. Objects relating to the textile industry were also uncovered. The presentation will give an overview of the archaeological finds relating to the various industries active at al-Shaykh Sa'id during the Amarna-period, and a comparison will be made with the faience and glass industry in the city of Amarna.

The cobalt content of Australian foods is unknown, and as this content is, at least in part, related to the respective concentrations in the Australian soil, data collected previously in other countries may not reflect the levels in Australian produce. To compare reported food cobalt levels to that found in Australian foods, one hundred and fifty different food and beverage items from each of the major food groups were selected for analysis, based on annual sales figures in Australia. Food digests were analysed for cobalt content using a Finnigan High Resolution Inductively Coupled Plasma Mass Spectrometer. While some variation in cobalt content was seen in a small selection of foods from different States, in general terms, the cobalt content of Australian foods is similar to that seen in data from other countries.

Introduction. -Les stomatodynies sont par définition des douleurs buccales sans cause trouvée à l'interrogatoire ou à l'examen. Une cause allergique est souvent suspectée par le malade ou son médecin. Notre but était d'évaluer l'intérêt des tests épicutanés pour mettre en évidence une cause allergique chez les malades atteints de stomatodynie. Malades et méthodes. -Il s'agissait d'une étude rétrospective monocentrique de malades ayant eu entre 1996 et 2003 des tests épicutanés pour chercher une cause allergique à des douleurs buccales non expliquées par une anomalie visible lors d'un examen réalisé à la consultation de pathologie buccale. Résultats. -Quarante malades ont été inclus (11 hommes, 29 femmes, âgés de 58 ans en moyenne) et 39 ont été exclus. Seize malades ont eu au moins un test positif, avec un total de 35 tests positifs. Par ordre de fréquence décroissante, il s'agissait des métaux, des dérivés mercuriels (sels de nickel : n = 5 ; de chrome : n = 3 ; de palladium : n = 2 ; phenylmercuric acétate : n = 2 ; thiomersal : n = 2 ; de cobalt : n = 1 ; d'or : n = 1 ; mercure : n = 1), et des résines (acrylates : n = 4). La pertinence de ces tests a été jugée comme probable trois fois et possible cinq fois, liée à l'existence de métaux ou de résines en bouche. Le baume du Pérou était positif * Auteur correspondant. Adresse L. Machet et al.

II 2016 KATA PENGANTAR Puji syukur kami ucapkan kepada Tuhan Yang Maha Esa atas segala limpahan Rahmat dan karuniaNya sehingga kami dapat menyelesaikan penyusunan makalah yang berjudul "Kesehatan dan Kesalamatan Kerja Pada Bidang Radioterapi" dalam bentuk maupun isinya yang sangat sederhana.

Ce papier se propose d'expliquer le pourquoi de la montée d'une « mondialisation compétitive » dans la quête des minerais dits stratégiques, d'un regard spécifique sur les nouveaux enjeux mondiaux de la transition énergétique, touchant le secteur automobile, et d'élucider le risque pour la RDC, avec son cobalt, de tomber dans le « piège des ressources ». À ce début du vingt-et-unième siècle, le contrôle et approvisionnement des minerais dits stratégiques ne cessent de demeurer l'enjeu majeur de différents acteurs globaux. Jusqu'à nouvel ordre, ces minerais s'imposent pour la concrétisation des projections d'un monde plus sophistiqué et écologique advenir. La montée d'une mondialisation compétitive se constate ainsi autour de ces minerais. Pour ce qui est des enjeux de la transition énergétique, touchant le secteur automobile, ainsi en transformation, le cobalt-minerai que la RDC possède en avantage quasi-absolu-est bien croché comme « nourriture stratégique » dans la chaîne productive des batteries au lithium-ion-jusqu'à preuve du contraire, composant indispensable des PHEVs. Le cobalt de la RDC se place ainsi au coeur de nouveaux enjeux mondiaux de la transition énergétique, et attire de la sorte les différents acteurs globaux dans son alentour. Une compétition sans merci s'annonce de cette manière autour de ce minerai stratégique. Compétition qui, se projette encore virulente avec la montée de la « compétition conservateurs-progressistes ». Ceci se présente non seulement comme opportunité pour la RDC d'accumuler plus des recettes et repenser son processus d'industrialisation-favorable pour son développement durable, mais aussi un risque pour elle de tomber une fois de plus dans le « piège des ressources ». Sur ce, la survie meilleure pour la RDC va ainsi dépendre de l'effectivité de sa « balance interne » vis-à-vis de différents acteurs globaux. Mots-Clés : Cobalt de la RDC, Minerai stratégique, Mondialisation compétitive, Nouveaux enjeux mondiaux, Piège des ressources. Abstract [English] This paper aims to explain why the rise of "competitive globalization" in the quest for so-called strategic minerals, to take a specific look at the new global stakes of the energy transition, affecting the automotive sector, and to elucidate the risk for DRC, with its cobalt, of falling into the "resource's trap". At this beginning of the twenty-first century, the control and supply of so-called strategic minerals continues to be a major stake of various global actors. Until further notice, these minerals are essential for the projection's realization of a more sophisticated and ecological world to come. The rise of a "competitive globalization" is thus observed around these minerals. As for the energy transition's stakes, affecting the automotive sector, thus in transformation, cobalt-a mineral that DRC possesses in quasi-absolute advantage-is well hooked as "strategic food" in the productive chain of lithium-ion batteries-until proven otherwise, an indispensable PHEVs' component. DRC's cobalt is thus at the heart of new global stakes of the energy transition, and in this manner attracts the various global actors in its vicinity. A ruthless competition is in this way shaping up around this strategic mineral [cobalt]. A competition that still projects itself as virulent with the rise of "conservatives-progressives' competition". This presents itself not only as an opportunity for DRC to accumulate more revenues and rethink its industrialization process-favorable for its sustainable development, but also as a risk for it to fall once again into the "resource's trap". On this, DRC's better survival will thus depend on the effectiveness of its "internal balance" vis-à-vis various global actors.

The density of states (DoS), electronic band structure and Fermi surfaces of compressed cobalt over 0-200 GPa and copper at 0 GPa have been simulated using ab initio density functional (DFT) calculations on Materials Studio using the DMol3 software package. Fermi surfaces and electronic band structures of copper and cobalt (fcc and hcp) are verified against the literature. The DoS for fcc (face-centered cubic) cobalt remains stable from 100–200 GPa with no anomalies. The DoS of hcp (hexagonal close-packed) cobalt shows a peak increasing to above the Fermi at 110 ± 10 GPa, this corresponds to the collapse of ferromagnetism at 120 ± 10 GPa and a crystal structure phase change from hcp to fcc into a mixed state at approximately 100 GPa. The merging of the spin up and down bands for hcp cobalt at 150 ± 10 GPa corresponds to the completion of both 3d electron pair spin coupling and also the extended transition from the mixed hcp-fcc state to a pure fcc state.

In 1969–70, a single Tang dynasty blue-spotted Gongyi sherd was found at Siraf, Iran, the main trading port on the Persian Gulf in the early Islamic period. This is the only known example of Chinese blue-and-white ware, whether low- or high-fired, found in the Middle East from such an early date. The sherd provides direct archaeological evidence for the Indian Ocean trade between China and the Middle East in the ninth century AD. The body paste, clear glaze and blue glaze or pigment were analyzed by thin-section petrography, scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDX) and X-ray fluorescence (XRF). The technological analysis reveals the different steps of the chaîne opératoire: clay mixing, slip and glaze
application, and decoration with the cobalt blue glaze before high-temperature firing. These steps are characteristic of Tang stoneware production at Gongyi in Henan province, China.
The use of cobalt blue pigment as part of a simple spotted decoration scheme on the Gongyi sherd, and its find context within the Middle East, provides evidence for the complex interplay and influence occurring between Chinese and Middle East ceramic industries at this time.
Closely comparable examples of contemporary low-fired earthenware ceramics with cobalt blue decoration on a white tin glaze manufactured within the Middle East also occur within the same assemblage from Siraf.

A single-laboratory validation study was conducted for the simultaneous determination of arsenic, cadmium, calcium, cobalt, copper, chromium, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in all major types of commercial fertilizer products by microwave digestion and inductively coupled plasma-optical emission spectroscopy analysis. This validation study proposes an extension and modification of AOAC 2006.03. The extension is the inclusion of calcium, copper, iron, magnesium, manganese, and zinc, and the modification is incorporation of hydrochloric acid in the digestion system. This dual acid digestion utilizes both hydrochloric and nitric acids in a 3 to 9 mL volume ratio/100 mL. In addition to 15 of the 30 original validation materials used in the 2006.03 collaborative study, National Institute of Standards and Technology Standard Reference Material 695 and Magruder 2009-06 were incorporated as accuracy materials. The main benefits of this proposed meth...

We have developed a novel MRI marker for prostate brachytherapy. The purpose of this study was to evaluate the changes in anisotropy when cobalt chloride complex contrast agent encapsulated contrast agent markers (C4-ECAM) were placed adjacent to an iodine-125 (I-125) titanium seed, and to verify that the C4-ECAMs were visible on magnetic resonance imaging (MRI) after radiation exposure. Two C4-ECAMs were verified to be MRI visible in a phantom before radiation exposure. The C4-ECAMs were then attached to each end of a 12.7-U (10-mCi) I-125 titanium seed in a polymer tube. Anisotropy was measured and analyzed with the seed alone and with attached C4-ECAMs by suspending thermoluminescent dosimeters in a water phantom in 2 circles surrounding the radioactive source with radius of 1 or 2 cm. A T1-weighted MRI evaluation of C4-ECAMs was then performed after exposure to the amount of radiation typically delivered during 1 month of prostate brachytherapy. Measured values of the anisotropy function F(r, ) for the I-125 seed with and without the C4-ECAMs were mutually statistically indistinguishable (standard error of the mean <4.2%) and agreed well with published TG-43 values for the bare seed. As expected, the anisotropy function an (r) for the 2 datasets (with and without C4-ECAMs) derived from the measured F(r, ) did not exhibit statistically measurable difference. Both datasets showed agreement with the published TG-43 an (r) for the bare seed. The C4-ECAMs were well visualized by MRI after 1 month of radiation exposure. There were no changes in anisotropy when the C4-ECAMs were placed next to an I-125 radioactive seed, and the C4-ECAMs were visualized after radiation exposure.

Cobalt-59 NMR experiments have been carried out on single-crystal and polycrystalline (powder) samples of (7)-tris(ethylenediamine)cobalt(III) chloride trihydrate, (7)-[Co(en) 3 ]Cl 3 Á 3H 2 O, and of its dehydrate. In addition, the X-ray crystal structure of the dehydrated sample has been determined. X-ray diffraction measurements confirm a long-held assumption that dehydration has only minor effects on the structure of the [Co(en) 3 ] 3+ cation. Nevertheless, these small differences have a detectable effect on the 59 Co nuclear magnetic resonance properties of these compounds; in particular, the nuclear quadrupole coupling constant, C Q . Straightforward identification of the c-axis for large single crystals of (7)-[Co(en) 3 ]Cl 3 Á 3H 2 O and of its dehydrate allowed us to obtain single-crystal 59 Co NMR data by orienting the crystals in an MAS rotor. Data collected on single crystals and polycrystalline samples indicate that C Q =À3.0570.05 and À2.8070.05 MHz for the hydrated and dehydrated samples, respectively; the signs have been assigned on the basis of a point charge model. The chemical shift tensor principal components were also determined: for the hydrated sample, d > ¼ 728172 ppm, d jj ¼ 700474 ppm and d iso ¼ 7189 ppm; for the dehydrated ARTICLE IN PRESS sample, d > ¼ 728872 ppm, d jj ¼ 700874 ppm and d iso ¼ 7195 ppm. The electric field gradient and chemical shift tensors are axially symmetric, as required by crystal symmetry. r

A new algorithm for simulation of chemical equilibria is developed, based on classical Newton-Raphson method applied to mass balance. This tool, named EST (Equilibrium Speciation Tool), is improved by using a robust Genetic Algorithm. In addition, EST works by using Excel spreadsheets and therefore offers the innovation of a great simplicity and versatility. In fact, it allows the users to simulate, or to obtain from experimental data, desired chemical-physical parameters as well as to interact with other available or freely created Excel tools. The reliability of this utility is here proved by comparison with some published data by other authors, concerning both complicated homogeneous and heterogeneous equilibria. In addiction its flexibility is tested computing thermodynamic parameters by using experimental calorimetric data referred to the complex formation of cobalt(II) with a macrocyclic ligand. A brief review and comparison of the relative robustness and quickness of main numerical methods are also reported.

The presence of LiCoO(2) and LiCo(x)Ni((1-x))O(2) in the cathodic material of Li-ion and Li-polymer batteries has stimulated the recovery of Co and Ni by hydrometallurgical processes. In particular, the two metals were separated by SX method and then recovered by electrochemical (galvanostatic and potentiostatic) processes. The metallic Ni has been electrowon at 250 A/m(2), pH 3-3.2 and 50 degrees C, with 87% current efficiency and 2.96 kWh/kg specific energy consumption. Potentiostatic electrolysis produces a very poor Ni powder in about 1 h with current efficiency changing from 70% to 45% depending on Ni concentration in the electrolyte. Current efficiency of 96% and specific energy consumption of 2.8 kWh/kg were obtained for Co at 250 A/m(2), pH 4-4.2 and 50 degrees C, by using a solution containing manganese and (NH(4))(2)SO(4). The Co powder, produced in potentiostatic conditions (-0.9 V vs. SCE, pH 4, room temperature) appears particularly suitable for Co recycling as cobaltit...

Wear of the polyethylene in total joint prostheses has been a source of morbidity and early device failure, which has been extensively reported in the last 20 years. Although research continues to attempt to reduce the wear of polyethylene joint-bearing surfaces by modifications in polymer processing, there is a renewed interest in the use of metal-on-metal bearing couples for hip prostheses. Wear testing of total hip replacement systems involving the couple of metal or ceramic heads on polymeric acetabular components has been performed and reported, but, until recently, there has been little data published for pin-on-disk or hip-simulator wear studies involving the combination of a metallic femoral head component with an acetabular cup composed of the same or a dissimilar metal. This study investigated the in vitro wear resistance of two cobalt/chromium/molybdenum alloys, which differed primarily in the carbon content, as potential alloys for use in a metal-on-metal hip-bearing couple. The results of pin-on-disk testing showed that the alloy with the higher (0.25%) carbon content was more wear resistant, and this alloy was therefore chosen for testing in a hip-simulator system, which modeled the loads and motions that might be exerted clinically. Comparison of the results of metal-on-polyethylene samples to metal-on-metal samples showed that the volumetric wear of the metal-on-polyethylene bearing couple after 5,000,000 cycles was 110 -180 times that for the metal-bearing couple. Polyethylene and metal particles retrieved from either the lubricant for pin-on-disk testing or hip simulator testing were characterized and compared with particles retrieved from periprosthetic tissues by other researchers, and found to be similar. Based upon the results of this study, metal-on-metal hip prostheses manufactured from the high carbon cobalt/chromium alloy that was investigated hold sufficient promise to justify human clinical trials.