Abstract  Cobalt ion-based coordination polymer nanowires were synthesized by using nitrilotriacetic acid (NA) as a chelating agent by a one-step hydrothermal approach. In the synthesis, cobalt ions were bonded with amino or carboxyl groups of NA to form one-dimension polymer nanowires, which can be confirmed by FTIR and TGA results. Our experimental results show that the morphologies of polymer nanowires greatly depend on the precursor salts, ratios between deionized water and isopropyl alcohol. The probable molecular formula and growth mechanism have been proposed. After heat treatment, the cobalt ion-based coordination polymer nanowires can be converted into porous Co(3)O(4) nanowires, which completely preserved the nanowire-like morphology. When used as anodes in lithium-ion batteries, the obtained porous Co(3)O(4) nanowires exhibited a high reversible capacity of 810 mA h g(-1) and stable cyclic retention at 30th cycle. The good electrochemical performance could be attributed to the porous nanostructure of Co(3)O(4), which provides pathways for easy accessibility of electrolytes and fast transportation of lithium ions.

Abstract  The mononuclear complex, [Co(TAMEN)](ClO(4))(2) (DMSO), containing the Mannich base N,N'-tetra-(4-antipyrylmethyl)-1,2-diaminoethane (TAMEN) as ligand, was synthesized and characterised by conductometric, electronic and infrared spectroscopic properties. The single-crystal X-ray structure show the presence of two well defined units, [Co(TAMEN)](2+) and (ClO(4))(-). The complex cation contains cobalt(II) in the pseudo octahedral environment created by the N(2)O(4) donor set of TAMEN. The cobalt(II) complex have been screened for its cytotoxic activity against three cultured human cell lines established from hepatoma (Hep G2), breast (MCF-7) and lung (A549) cancers as well as on non-tumor bovine kidney (MDBK) cells. The cytotoxic activity of the ligand TAMEN was assessed on one tumor (Hep G2) and one non-tumor (MDBK) cell lines. The cobalt(II) compound was found to decrease in a time- and concentration- dependent manner the viability of tumor (A549, MCF-7, Hep G2) cell lines, while the ligand TAMEN expressed proliferative activity on hepatoma (HepG2) and bovine kidney (MDBK) cells, especially after prolonged incubation.

Abstract  Poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p (AMPS))-based microgel is prepared for metal nanoparticle preparation of Co and Ni and then used in hydrolysis of NaBH4. The Co(II) ions from different anion-containing sources is used for loading of p(AMPS) and used in Co nanoparticle preparation. It is found that loading of Co(II) into p(AMPS) is in the order of Cl- > CH3COO- > NO3- as well as the formed corresponding particles. The porous p(AMPS) microgel is prepared and used in metal nanoparticle preparation and porous p(AMPS) can load more Co(II) than p(AMPS)-silica and bare p(AMPS). The Co nanoparticle- containing composites also give catalytic performances in that order. The activation energy for hydrolysis of NaBH4 by p(AMPS)-Co microgel composites is calculated as 29.80 kJ/mol, that is as low as Ru nanoparticle-containing bulk p(AMPS) hydrogels. It is further revealed that the microgels based on p(AMPS) are versatile, can be used repeatedly up to five times without any loss of catalytic activity (only about 3%) and with no loss in conversion. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Abstract  A general method to produce self-assembled metal oxides with hollow structures is developed by controlling the net redox potentials. Nanostructured CoOOH and CeO2 hollow microspheres have been successfully prepared by this method. The synthesized CoOOH hollow spheres are versatile precursors for nanomaterials of cobalt oxide derivatives (eg. CO3O4, LiCoO2), and also possess excellent catalytic activity.

Abstract  Coverage dependence adsorption of intermediates typical for syngas conversion is studied theoretically on FCC-cobalt surfaces. The FCC structure is relevant for cobalt particles active in this reaction. Emphasis on the analysis is on the thermodynamics of surface reconstruction as a function of surface adsorbate and surface coverage. An important result is the finding that only adsorbed carbon induced reconstruction of FCC-CO(1 1 1) to FCC-CO(1 0 0) as well as the clock reconstruction for the two surfaces. (C) 2007 Elsevier B.V. All rights reserved.

Abstract  The effects of reaction conditions on the Fischer-Tropsch activity and product distribution of an alkali-earth metal promoted cobalt based catalyst were studied. The influence of the promoter on the reducibility and cobalt particle size was studied by different techniques, including N-2 adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption and acid-base titrations. Experiments were carried out on a bench-scale fixed bed reactor and catalysts were prepared by incipient wetness impregnation. It was observed that addition of a small amount of calcium oxide as a promoter (0.6 wt.%) improved the cobalt oxide reducibility and reduced the formation of cobalt-aluminate species. A positive correlation between basicity and particle size was observed. In terms of FTS results, CO conversion and C-5(+) selectivity were found to be enhanced by the addition of this promoter. It was important to note that the addition of calcium shifted the distribution to mainly C-16-C-18 hydrocarbons fraction, which could be greatly considered for a diesel formulation. Furthermore, the variation of the reaction conditions seemed to influence product distribution in a lesser extent than unpromoted catalyst. Also, a displacement of hydrocarbon distribution to higher molecular weight with decreasing space velocity and temperature was observed. Moreover, the addition of calcium to the cobalt based catalyst was found to greatly maintain selectivity to C-5(+) for a wide range of H-2/CO molar ratios. (c) 2010 Elsevier Ltd. All rights reserved.

Abstract  A highly active and selective manganese oxide-promoted silica-supported cobalt catalyst for the Fischer-Tropsch reaction is reported. Co/MnO/SiO2 catalysts were prepared via impregnation of a cobalt nitrate and manganese nitrate precursor, followed by drying and calcination in an NO/He flow. The catalysts were studied with STEM-EELS, infrared spectroscopy measurements of adsorbed CO and Steady-State Isotopic Transient Kinetic Analysis experiments. Based on those experiments, a relation between C5+-selectivity and surface-coverages of CHx-intermediates on cobalt was found.

Abstract  There is concern that offshore oil platforms off Southern California may be contributing to environmental contaminants accumulated by marine fishes. To examine this possibility, 18 kelp bass (Paralabrax clathratus Girard, 1854), 80 kelp rockfish (Sebastes atrovirens Jordan and Gilbert, 1880), and 98 Pacific sanddab (Citharichthys sordidus Girard, 1854) were collected from five offshore oil platforms and 10 natural areas during 2005-2006 for whole-body analysis of 63 elements. Forty-two elements were excluded from statistical comparisons as they (1) consisted of major cations that were unlikely to accumulate to potentially toxic concentrations; (2) were not detected by the analytical procedures; or (3) were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. However, the concentrations of copper, selenium, titanium, and vanadium in Pacific sanddab were unusual because small individuals exhibited either no differences between oil platforms and natural areas or significantly lower concentrations at oil platforms than at natural areas, whereas large individuals exhibited significantly higher concentrations at oil platforms than at natural areas.

Abstract  Cobalt oxide was synthesized by mechano-chemical process in solid phase and was characterized by particle size analysis, nitrogen adsorption, XRD and DRIFT. A study was performed to evaluate the catalytic activities of cobalt oxide for oxidation of benzyl alcohol in liquid phase, using toluene as solvent. Benzaldehyde and benzoic acid were identified as the reaction products. Effects of various parameters like reaction time, temperature, catalyst loading and partial pressure of oxygen on reaction performance were studied. Activation energy was found as 46.14 kJ/mol. Langmuir-Hinshelwood type of mechanism was found to be applicable to experimental data. The catalyst was found to be heterogeneous in nature, which can be easily separated from the reaction mixture by filtration.

Abstract  Small-molecule activation by transition metals is essential to numerous organic transformations, both biological and industrial. Creating useful metal-mediated activation systems often depends on stabilizing the metal with uncommon low oxidation states and low coordination numbers. This provides a redox-active metal center with vacant coordination sites well suited for interacting with small molecules. Monovalent nickel species, with their d(9) electronic configuration, are moderately strong one-electron reducing agents that are synthetically attractive if they can be isolated. They represent suitable reagents for closing the knowledge gap in nickel-mediated activation of small molecules. Recently, the first strikingly stable dinuclear β-diketiminate nickel(I) precursor complexes were synthesized, proving to be suitable promoters for small-molecule binding and activation. They have led to many unprecedented nickel complexes bearing activated small molecules in different reduction stages. In this Account, we describe selected achievements in the activation of nitrous oxide (N(2)O), O(2), the heavier chalcogens (S, Se, and Te), and white phosphorus (P(4)) through this β-diketiminatonickel(I) precursor species. We emphasize the reductive activation of O(2), owing to its promise in oxidation processes. The one-electron-reduced O(2) activation product, that is, the corresponding β-diketiminato-supported Ni-O(2) complex, is a genuine superoxonickel(II) complex, representing an important intermediate in the early stages of O(2) activation. It selectively acts as an oxygen-atom transfer agent, hydrogen-atom scavenger, or both towards exogenous organic substrates to yield oxidation products. The one-electron reduction of the superoxonickel(II) moiety was examined by using elemental potassium, β-diketiminatozinc(II) chloride, and β-diketiminatoiron(I) complexes, affording the first heterobimetallic complexes featuring a [NiO(2)M] subunit (M is K, Zn, or Fe). Through density functional theory (DFT) calculations, the geometric and electronic structures of these complexes were established and their distinctive reactivity, including the unprecedented monooxygenase-like activity of a bis(μ-oxo)nickel-iron complex, was studied. The studies have further led to other heterobimetallic complexes containing a [NiO(2)M] core, which are useful for understanding the influence of the heterometal on structure-reactivity relationships. The activation of N(2)O led directly to the hydrogen-atom abstraction product bis(μ-hydroxo)nickel(II) species and prevented isolation of any intermediate. In contrast, the activation of elemental S, Se, and Te with the same nickel(I) reagent furnished activation products with superchalcogenido E(2)(-) (E is S, Se, or Te) and dichalcogenido E(2)(2-) ligand in different activation stages. The isolable supersulfidonickel(II) subunit may serve as a versatile building block for the synthesis of heterobimetallic disulfidonickel(II) complexes with a [NiS(2)M] core. In the case of white phosphorus, the P(4) molecule has been coordinated to the nickel(I) center of dinuclear β-diketiminatonickel(I) precursor complexes; however, the whole P(4) subunit is a weaker electron acceptor than the dichalcogen ligands E(2), thus remaining unreduced. This P(4) binding mode is rare and could open new doors for subsequent functionalization of P(4). Our advances in understanding how these small molecules are bound to a nickel(I) center and are activated for further transformation offer promise for designing new catalysts. These nickel-containing complexes offer exceptional potential for nickel-mediated transformations of organic molecules and as model compounds for mimicking active sites of nickel-containing metalloenzymes.

Abstract  The heats of mixing of aqueous solutions of copper(II) or nickel(II) nitrate in water + acetamide (AA) mixtures in the existing range of amide concentrations have been studied. A rise in the amide concentration enhances solvation more strongly in copper(II) salt solutions. Data are analyzed with reference to previous results on the enthalpies of transfer of the salts studied in water + formamide (FA) and water + N,N- dimethylformamide (DMF) mixtures. Electronic absorbance spectra have been recorded at a fixed electrolyte concentration for all thermochemically studied systems, and a linear correlation has been found between the enthalpy of transfer of Cu(NO3)(2) and the optical density of the solution. The enhanced solvation of copper(II) nitrate in aqueous acetamide is due to inner- sphere interactions between the cation and acetamide; that of nickel(II) nitrate is more due to outer-sphere interactions.

Abstract  Paramagnetic transition-metal complexes assembled on surfaces are of great interest for potential applications in organic spintronics. The magnetochemical interactions of the spin of the metal centers with both ferromagnetic surfaces and optional axial ligands are yet to be understood. We use a combination of X-ray magnetic circular dichroism (XMCD) and quantum-chemical simulations based on density functional theory (DFT + U) to investigate these metal-organic interfaces with chemically tunable magnetization. The interplay between an optional axial ligand (NO, spin S = 1/2 or NH3, S = 0) and Ni and Co ferromagnetic surfaces affecting the spin of Co(II) tetraphenylporphyrin (d(7), S = 1/2), Fe(II) tetraphenylporphyrin (d(6), S = 1), Mn(II) tetraphenylporphyrin (d(5), S = 5/2) and Mn(II) phthalocyanine (d(5), S = 3/2) is studied. We find that the structural trans effect on the surface rules the molecular spin state, as well as the sign and strength of the exchange interaction with the substrate. We refer to this observation as the surface spin-trans effect.

Abstract  Abstract Context: We describe a case of acute retinal toxicity caused by an intraocular foreign body composed of a cobalt alloy. Case presentation: A 36-year-old man presented to an outside clinic with a traumatic cataract and corneal laceration of his left eye, which had occurred while grinding a shelf. The lacerated cornea was closed primarily and the traumatic cataract was phacoemulsified. He was transferred to our hospital due to identification of a metallic intraocular foreign body in the vitreous. On arrival at our institution, the intraocular foreign body was removed as soon as possible after vitrectomy. On the first postoperative day, vasculitis and serous retinal detachment were observed on the retina at the previous site of the foreign body. Two months after surgery, atrophy of nearly half of the inferior retina was noted on funduscopy, and visual acuity was such that the patient could only count fingers at 30 cm. Analysis of the foreign body revealed that it was composed of 84.99% tungsten carbide, 15% cobalt and had traces of titanium and alumina. Discussion: Cobalt containing metallic foreign bodies should be immediately removed, as they have the potential to cause permanent visual disturbance.

Abstract  Tungsten carbide-cobalt (WC-Co) nanoparticle composites have wide applications because of their hardness and toughness. WC-Co was classified as "probably carcinogenic" to humans by the International Agency for Research on Cancer (IARC) in 2003. It is believed that the toxicity and carcinogenesis of WC-Co is associated with particle size. Recent studies demonstrated that the tumor suppressor gene programmed cell death 4 (PDCD4) and its upstream regulator miR-21 have been considered as oncogenes for novel cancer prevention or anticancer therapies. The present study examined the effects of WC-Co nanoparticles on miR-21-PDCD4 signaling in a mouse epidermal cell line (JB6 P+). The results showed that (i) exposure of JB6 cells to WC-Co stimulated a increase of miR-21 generation; (ii) WC-Co also caused inhibition of PDCD4, a tumor suppressor protein and downstream target of miR-21, expression in JB6 cells; (iii) inhibition of ERKs with ERK inhibitor U0126 significantly reversed WC-Cominus;induced PDCD4 inhibition, but inhibition of p38 with p38 inhibitor SB203580 did not; and (iv) ROS scavengers, N-acetyl-L-cysteine and catalase, blocked the inhibitory effect of WC-Co on PDCD4 expression, while superoxide dismutase promoted the inhibitory effect. These findings demonstrate that WC-Co nanoparticles induce miR-21 generation, but inhibit PDCD4 production, which may be mediated through ROS, especially endogenous H2O2, and ERK pathways. Unraveling the complex mechanisms associated with these events may provide insights into the initiation and progression of WC-Co-induced carcinogenesis.

Abstract  The quality of diamond films deposited on cemented tungsten carbide substrates (WC-Co) is limited by the presence of the cobalt binder. The cobalt in the WC-Co substrates enhances the formation of nondiamond carbon on the substrate surface, resulting in a poor film adhesion and a low diamond quality. In this study, we investigated pretreatments of WC-Co substrates in three different approaches, namely, chemical etching, laser etching, and laser etching followed by acid treatment. The laser produces a periodic surface pattern, thus increasing the roughness and releasing the stress at the interfaces between the substrate and the grown diamond film. Effects of these pretreatments have been analyzed in terms of microstructure and cobalt content. Raman spectroscopy was conducted to characterize both the diamond quality and compressive residual stress in the films.

Abstract  The use of novel materials on the modern battlefield, both in military munitions as well as in Improvised Explosive Devices, opens the possibility of wounds with embedded fragments whose health effects and toxicity characteristics have not been fully investigated, if at all. The costly and time-consuming nature of standard two-year lifespan studies prohibits the testing of many materials. In this report, we describe an in vitro system for rapidly assessing potential toxicity of metals and metal mixtures. Using rat L6 and mouse C2C12 skeletal muscle cells and tests for cellular viability, we have shown that two militarily relevant tungsten alloy mixtures (W/Ni/Co and W/Ni/Fe) significantly decreased the metabolic viability of rat L6 cells, whereas the viability of mouse C2C12 cells was not affected by W/Ni/Co and only slightly affected by W/Ni/Fe. In addition, viability assessed through lysosomal uptake of neutral red dye was not affected by either mixture in either cell line indicating that the mitochondria may be the target organelle of these unique metal mixtures. Development of this in vitro screening system may provide a procedure by which the potential toxicities of embedded metal fragments can be rapidly assessed.

Abstract  Tungsten trioxide (WO(3)) nanostructures were synthesized by hydrothermal method using sodium tungstate (Na(2)WO(4).2H(2)O) alone as starting material, and sodium tungstate in presence of ferrous ammonium sulfate [(NH(4))(2)Fe(SO(4))(2).6H(2)O] or cobalt chloride (CoCl(2).6H(2)O) as structure-directing agents. Orthorhombic WO(3) having a rectangular slab-like morphology was obtained when Na(2)WO(4).2H(2)O was used alone. When ferrous ammonium sulfate and cobalt chloride were added to sodium tungstate, hexagonal WO(3) nanowire clusters and hexagonal WO(3) nanorods were obtained, respectively. The crystal structure and orientation of the synthesized products were studied by X-ray diffraction (XRD), micro-Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), and their chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS). The optical properties of the synthesized products were verified by UV-Vis and photoluminescence studies. A photodegradation study on Procion Red MX 5B was also carried out, showing that the hexagonal WO(3) nanowire clusters had the highest photodegradation efficiency.

Abstract  A 35-year-old man was admitted to our hospital because of abnormal shadows on the chest radiograph and dry cough and exertional dyspnea. He was given a diagnosis of hard metal lung disease 15 years previously and was treated with corticosteroid. Laboratory examination revealed hypoxemia and reduced pulmonary vital capacity. Chest radiograph and high-resolution computed tomography (HRCT) on admission showed ground-glass opacities with volume loss and small cystic spaces. Bronchoalveolar lavage fluid (BALF) demonstrated bizarre multinucleated giant cells and transbronchial lung biopsy (TBLB) specimens showed interstitial pneumonia with multinucleated giant cells. He has worked as a metal grinder, and tungsten was detected in his BALF metal analysis. His illness was diagnosed as hard metal lung disease with giant cell interstitial pneumonia (GIP). We considered this case as a type of chronic hypersensitivity pneumonitis due to his high sensitivity and his disease worsened gradually for four years. Since hard metal lung disease may recur in individuals with high sensitivity, we should always be aware of the possibility of recurrence of this disease.

Abstract  Two new nano-dimensional square grid metal-organic polymers, {[Cd(1,3-bix)(2)(H2O)(2)] (NO3)(2)}(n) (1) and [Cd(1,3-bix)(2)(NO3)(2)](n) (2) (1,3-bix=1,3-bis (imidazol-1-yl-methyl)benzene), have been synthesized and structurally characterized by single- crystal X-ray crystallography and FT-IR spectroscopy. Polymers 1 and 2 are 2-D layer structures consisting of nano-dimensional square grid units. The photoluminescent properties of 1 and 2 were investigated.

Abstract  The hydrothermal reaction of cadmium nitrate hydrate (Cd (NO3)(2)center dot 4H(2)O) with p-terphenyl-type 4,4'-(1,4-phenylene)bis(2,6-dimethyl-3,5- pyridinedicarboxylic acid) (H4L), and phenanthroline (phen) in the presence of triethylamine leads to a three-dimensional supramolecular aggregate {[Cd-3(phen)(3)(HL)(2)(H2O)(2)]center dot 4.25H(2)O}. (1). In 1, the T-type second building units construct independent one-dimensional (I-D) metal-organic nanotubes (MONTs) with 6(3) topology containing distinct axially asymmetric subunits [R-Cd-3(HL) and S-Cd-3(HL)]. The adjacent RR-Cd-5(HL)(2) supersubunits form a hydrophilic intertube chiral channel (I), and the SS-Cd-5(HL)2 supersubunits generate another type of hydrophilic intertube chiral channel (II). These two types of chiral channels encapsulate two corresponding types of helical water-chains with three pseudo screw axes, exhibiting a novel chirality transformation and transfer, namely, R-Cd-3(HL) -> RR-Cd-5(HL)(2) -> chiral channel (I) - left-handed (M) water-helix, and S-Cd-3(HL) - SS-Cd-5(HL)(2) - chiral channel (II) - right- handed (P) water-helix. Photoluminescence and nitrogen adsorption behavior of 1 have been examined.

Abstract  Cobalt and Nickel Phthalocyanines (CoPc, NiPc) were synthesised by chemical route. Phthalocyanines (Pcs) were characterized by different techniques such as, XRD, UV Visible, and FTIR. Samples in the pellet form were prepared for gas sensing applications. The effect of NO(2) at different concentrations in air at room temperature on the electrical conductivity of CoPc and NiPc has been studied. Sensitivity, response time and recovery time of sensors for different NO(2) concentrations were studied. The comparison of these materials as NO(2) gas sensor is discussed in this research paper.

Abstract  The reactions of cobalt(II) complexes of tetraazamacrocyclic tropocoronand (TC) ligands with nitric oxide (NO) were investigated. When [Co(TC-5,5)] was allowed to react with NO(g), the {CoNO}(8) mononitrosyl [Co(NO)(TC-5,5)] was isolated and structurally characterized. In contrast, a {Co(NO)(2)}(10) species formed when [Co(TC-6,6)] was exposed to NO(g), and the nitrito [Co(NO(2))(TC-6,6)] complex was structurally and spectroscopically characterized from the reaction mixture. The {Co(NO)(2)}(10) species was assigned as the bis(cobalt dinitrosyl) complex [Co(2)(NO)(4)(TC-6,6)] by spectroscopic comparison with independently synthesized and characterized material. These results provide the first evidence for the influence of tropocoronand ring size on the nitric oxide reactivity of the cobalt(II) complexes.

Abstract  Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe(2)O(4) was obtained using a conventional ceramic method and Bi(2)O(3) was used as additive in order to obtain liquid-phase sintered samples. Bi(2)O(3) was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives.

Abstract  Solution combustion using urea as a fuel was employed to synthesise Co oxide and Al(2)O(3)-, SiO(2)- and TiO(2)-supported Co oxide catalysts. The catalysts were characterised using several techniques such as N(2) adsorption/desorption, XRD, FTIR, UV-vis diffuse reflectance and SEM-EDX, and their catalytic activity was evaluated in phenol degradation in aqueous solution with sulphate radicals. Solution combustion is a simple and effective method in preparation of supported Co catalysts. Co(3)O(4) was the major Co crystal phase in the samples prepared via the combustion synthesis. Bulk Co(3)O(4) particles were not effective in reaction, but supported Co oxides showed higher activity than unsupported Co oxide. The supports influenced Co dispersion and catalytic activity. Co/TiO(2) exhibited the highest activity, but it deactivated much faster than other two supported catalysts. Co/SiO(2) showed a comparable activity to Co/Al(2)O(3) and the best stability among the three Al(2)O(3)-, SiO(2)- and TiO(2)-supported Co catalysts.