Abstract  A facile hydrothermal reduction route based on a precipitate slow-release controlled process was developed to fabricate highly ordered dendritic cobalt microcrystals using cetyltrimethylammonium bromide (CTAB) in high alkali media. The shape, structure, and magnetic properties of the final products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), electron diffraction (ED), and vibrating sample magnetometry (VSM). The results showed that the sample is hexagonal close-packed Co coexisting with cubic close-packed Co: the length of the main trunk is about 8 pm and diameter of the branches is 0.5-2 mu m. Magnetic measurement at 300 K showed that these In microstructures exhibited ferromagnetic character. The probable formation mechanism of the microcrystals was discussed on the basis of the experimental results. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  Significant studies have achieved beautiful control in particle size, while the shape- and phase-control synthesis of nanoparticles remains an open challenge. In this study, we have developed a generalized methodology to selectively prepare either NaCl-type (reduced form) or spinel-type ferrite (oxidized form) M-Fe-O (M = Mn, Co) crystallites with high reproducibility. A two-step heating process was able to control formation of two types of crystal phase, either a thermodynamic spinel-type under air or a kinetic-control of NaCl-type (rock salt structure) under Ar in a cubic morphology. On the other hand, the three-step heating procedure in air obtained the spinel-type with a thermodynamic equilibrium octahedral shape exclusively. Either using metal acetates (M(ac)(2)) or metal acetylacetonates (M(acac)(2)) as the starting precursors (M = Mn, Co) can be introduced to prepare NaCl-type (reduced form) or spinel-type ferrite (oxidized form) crystallites with identical experimental parameters, including precursor concentration, reaction temperature, reaction time, and heating rate. The oleic acid molecule, reaction temperature, and heating rate employed in the synthesis were carefully examined and found acting as determined roles behind the reaction processes. Apart from the previous literature reports as shape-directed and/or stabilizing agents, the oleic acid molecule played an additional phase-tuning role.

Abstract  PURPOSE: Total body irradiation (TBI) has been used for bone marrow transplant for hematologic and immune deficiency conditions. The goal of TBI is to deliver a homogeneous dose to the entire body, with a generally accepted range of dose uniformity being within ± 10% of the prescribed dose. The moving table technique for TBI could make dose uniform in whole body by adjusting couch speed. However, it is difficult to accurately estimate the actual dose by calculation and hence in vivo dosimetry (IVD) is routinely performed. Here, the authors present patterns of patient-specific IVD in 161 TBI patients treated at our institution.

METHODS: Cobalt-60 teletherapy unit (Model C9 Cobalt-60 teletherapy unit, Picker X-ray Corporation) with customized moving bed (SITI Industrial Products, Inc., Fishers, IN) were used for TBI treatment. During treatment, OneDose(TM) (Sicel Technology, NC) Metal Oxide-silicon Semiconductor Field Effect Transistor detectors were placed at patient body surface; both entrance and exit side of the beam at patient head, neck, mediastinum, umbilicus, and knee to estimate midplane dose. When large differences (>10%) between the prescribed and measured dose were observed, dose delivery was corrected for subsequent fractions by the adjustment of couch speed and/or bolus placement. Under IRB exempt status, the authors retrospectively analyzed the treatment records of 161 patients who received TBI treatment between 2006 and 2011.

RESULTS: Across the entire cohort, the median ± SD (range) percent variance between calculated and measured dose for head, neck, mediastinum, umbilicus, and knee was -2.3 ± 10.2% (-66.2 to +35.3), 1.1 ± 11.5% (-62.2 to +40.3), -1.9 ± 9.5% (-66.4 to +46.6), -1.1 ± 7.2% (-35.2 to +42.9), and 3.4 ± 12.2% (-47.9 to +108.5), respectively. More than half of treatments were within ± 10% of the prescribed dose for all anatomical regions. For 80% of treatments (10%-90%), dose at the umbilicus was within ± 10%. However, some large differences greater than 35% were also found at several points. For one case, the knee received double the prescribed dose. When the dose differences for multiple fractions were averaged, compliance (± 1 0%) between the prescription and measured dose was improved compared to the dose difference of the first single fraction, for example, as at umbilicus, which improved from 83.9% to 98.5%.

CONCLUSIONS: Actual dose measurement analysis of TBI patients revealed a potentially wide variance from the calculated dose. Based from their IVD method for TBI using Cobalt-60 irradiator and moving table, ± 10% over entire body is hard to achieve. However, it can be significantly improved with immediate feedback after the first fraction prior to subsequent treatments.

Abstract  A facile two step process was developed for the synthesis of porous Co3O4 nanorods-reduced graphene oxide (PCNG) hybrid materials based on the hydrothermal treatment cobalt acetate tetrahydrate and graphene oxide in a glycerol-water mixed solvent, followed by annealing the intermediate of reduced graphene oxide-supported Co(CO3)0.5(OH)·0.11H2O nanorods in a N2 atmosphere. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. It is shown that the obtained PCNG have intrinsic peroxidase-like activity. The PCNG are utilized for the catalytic degradation of methylene blue. The good catalytic performance of the composites could be attributed to the synergy between the functions of porous Co3O4 nanorods and reduced graphene oxide.

Abstract  BACKGROUND: Excessive absorption of cobalt has been associated with cases of dilated cardiomyopathy in the past, but it is unclear whether occupationally exposed populations are at risk.

OBJECTIVE: To assess the possible relationship between occupational exposure to cobalt and incipient signs of dilated cardiomyopathy.

METHODS: A cross-sectional survey was conducted in a cobalt production facility in Belgium constituting one of the largest occupational populations worldwide (n=256 male workers). Exposure to cobalt was assessed by measuring urinary cobalt concentration (µg/gcreat), reflecting recent exposure, and by computing an integrated exposure index (µg/gcreat×years), reflecting long-term exposure. The effect on the myocardium was investigated by echocardiography and electrocardiography, and dose-effect relations with cobalt exposure were traced by multiple regression analysis.

RESULTS: No dose-effect relationship between exposure to cobalt and parameters reflecting dilated cardiomyopathy was found in a population of workers characterised by a median recent cobalturia of 4 µg/gcreat and a median long-term cobalturia of 100 µg/gcreat×years. A reduction in the dimensions of the left ventricular internal cavity was associated with recent exposure to cobalt.

CONCLUSIONS: Occupational exposure to cobalt does not appear associated with incipient signs of dilated cardiomyopathy within the gradient of exposure recorded in this population.

Abstract  Long term in vitro biostability of thermoplastic polyurethanes (TPUs) containing mixed polyisobutylene (PIB)/poly(tetramethylene oxide) (PTMO) soft segment was studied under accelerated conditions in 20% H(2)O(2) solution containing 0.1M CoCl(2) at 50 degrees C to predict resistance to metal ion oxidative degradation (MIO) in vivo. The PM-based TPUs showed significant oxidative stability as compared to the commercial controls Pellethane (TM) 2363-55D and 2363-80A. After 12 weeks in vitro the PIB-PTMO TPUs with 10-20% PTMO in the soft segment showed 6-10% weight loss whereas the Pellethane (TM) TPUs degraded completely in about 9 weeks. Attenuated total reflectance Fourier transform infrared spectroscopy confirmed the degradation of Pellethane (TM) samples via MIO by the loss of the similar to 1110 cm(-1) aliphatic C-O-C stretching peak height attributed to chain scission, and the appearance of a new peak at similar to 1174 cm(-1) attributed to crosslinking. No such changes were apparent in the spectra of the PIB-based TPUs. The PO-based TPUs exhibited 10-30% drop in tensile strength compared to 100% for the Pellethane (TM) TPUs after 12 weeks. The molecular weight of the PIB-based TPUs decreased slightly (10-15%) at 12 weeks. The Pellethane (TM) TPUs showed a dramatic decrease in M(n) and an increase in low molecular weight degradation product. Scanning electron microscopy (SEM) showed severe cracking in the Pellethane (TM) samples after 2 weeks, whereas the PIB-based TPUs exhibited a continuous surface morphology. The weight loss, tensile, and SEM data correlate well with each other and indicate excellent biostability of these materials. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 95A: 774-782, 2010.

Abstract  The negative electrode development for a nickel-metal hydride battery (Ni-MH) prototype was performed with the following procedure: (1) the Lm(0.95)Ni(3.8)Co(0.3)Mn(0.3)Al(0.4) (Lm = lanthanum rich mischmetal) intermetallic alloy was elaborated by melting the pure elements in an induction furnace inside a boron nitride crucible under an inert atmosphere, (2) the obtained alloy was crushed and sieved between 44 and 74 pm and mixed with teflonized carbon; (3) the compound was assembled together with a current collector and pressed in a cylindrical matrix. The obtained electrode presented a disc shape, with 11 mm diameter and approximately 1 mm thickness. The crystalline structure of the hydrogen storage alloy was examined using X-ray diffractometry. The measured hcp lattice volume was 1.78% larger than the precursor LaNi(5) intermetallic alloy, increasing the available space for hydrogen movement. Energy dispersive spectroscopy (EDS) and scanning electronic microscopy (SEM) measurements were used before and after hydriding in order to verify the alloy sample homogeneity. The negative electrode was electrochemically tested by using a laboratory cell. It activates almost totally in its first cycle, which is an excellent characteristic from the commercial point of view. The maximum discharge capacity reached was 314.2 mA h/g in the 10th cycle. (C) 2009 Elsevier B.V. All rights reserved.

Abstract  The complex formed by lead and 4,5-Dihydroxy-3-(p Sulfophenylazo)-2,7-Naphthalene Disulfonic Acid Trisodium Salt (SPADNS) was able to be adsorbed on the HMDE. In this investigation we were able to determine lead (II) in water and edible oil samples, using Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV) technique. The influence of variables is completing studied. Linear dependence between the peak current and lead concentration in the (NH(3)/NH(4)Cl) buffer in pH=7.5 observed in the range 0.7 - 115.0 ng ml(-1) of Pb(II), for accumulation time 100 s and sweep rate 24 mV s(-1). The detection limit for Pb(II) was 0.110 ng ml(-1), and the RSD at a concentration level of 45 ng ml(-1) was 1.48%. This method has been applied for the determination of Lead in Edible Oil and Water Samples with satisfactory results.

Abstract  Here we design an electrochemical DNA sensor, in which electrochemically active compound play a dual role - electrochemical indicator and anchor for probe DNA immobilization. [Co(phen)(2)(L-Cys)] (phen = 1,10-phenanthroline) was selected to play the dual roles, and was immobilized on gold electrode surface in two steps. The designed DNA sensor showed good selectivity, which can be used for one-base mismatch discrimination. Meanwhile, the peak intensity was linear with the logarithmic value of the complementary target DNA concentration from 1 pM to 1 mu M with a correlation coefficient of 0.99. (C) 201 2 Elsevier B.V. All rights reserved.

Abstract  The sorption behaviour of cobalt by Mg2Al layered double hydroxide (Mg2Al LDH) was investigated as a function of contact time under ambient conditions. The sorption of cobalt onto Mg2Al layered double hydroxide increases sharply within the first 1 h, then it rises slowly and reaches equilibrium in 5 h. The kinetic sorption is fitted by the pseudo-second-order model very well. The results manifest that Mg2Al layered double hydroxide is a promising material for the preconcentration and separation of pollutants from large volumes of aqueous solutions.

Abstract  A single crystal of adipic acid dihydrazide, ADH, has been analyzed. Its reaction with Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), Ag(+), Pd(2+) and/or Pt(2+) gave homometallic and heterometallic complexes which are characterized by partial elemental analysis, spectra (MS, ESR, (1)H NMR, electronic; IR), thermal analysis and magnetic measurements. Some complexes: Zn0.73Cu(ADH)Cl4·H2O; Zn0.71Hg0.36(ADH)Cl4·H2O; Zn0.65Cd0.46(ADH)Cl4·½H2O; Zn0.75Co0.41(ADH-2H)Cl2·3H2O; Cd0.85Co0.43(ADH)Cl4·½EtOH were isolated having nonstiochiometric metal ratios. The ligand behaves as a neutral (bidentate or tetradentate) and/or binegative tetradentate. A square-pyramid, square-planar and tetrahedral structures were proposed for the homo Co(II), Cu(II) and Ni(II) complexes, respectively. A similar and different stereochemistry around each metal ion (tetrahedral+tetrahedral; tetrahedral+square-planar; tetrahedral+tetrahedral and/or tetrahedral+octahedral) was suggested for the heterometallic complexes. Some complexes were found highly stable with stability point >240°C; the most stable is [HgNi(ADH-2H)Cl2]. The presence of diamagnetic atom (Zn, Cd or Hg) reduces the magnetic moments and gave anomalous moments. The degradation steps and the hydrated complexes are confirmed through the TGA study. The order of covalency of [Zn0.73Cu(ADH)Cl4]·H2O, [CdCu(ADH)Cl4]·H2O and [HgCu(ADH-2H)Cl2] matches with the size of the second metal (Zn complex>Cd complex>Hg complex). Some heterometallic complexes were found nonstoichiometric through the analysis of their metal content and supported by TGA.

Abstract  In the monomeric title complex, [Co(C6H8O4)(C10H9N3)(H2O)2]·3H2O, the distorted octa-hedral CoN2O4 coordination environment comprises two N-atom donors from the bidentate di-pyridyldi-amine ligand, two O-atom donors from one of the carboxyl-ate groups of the bidentate chelating adipate ligand and two water mol-ecules. In addition, there are three solvent water mol-ecules which are involved in both intra- and inter-unit O-H⋯O hydrogen-bonding inter-actions, which together with an amine-water N-H⋯O hydrogen bond produce a three-dimensional framework.

Abstract  To remove Hg(0) in coal combustion flue gas and eliminate secondary mercury pollution of the spent catalyst, a new regenerable magnetic catalyst based on cobalt oxide loaded magnetospheres from fly ash (Co-MF) was developed. The catalyst, with an optimal loading of 5.8% cobalt species, attained approximately 95% Hg(0) removal efficiency at 150 °C under simulated flue gas atmosphere. O2 could enhance the Hg(0) removal activity of magnetospheres catalyst via the Mars-Maessen mechanism. SO2 displayed an inhibitive effect on Hg(0) removal capacity. NO with lower concentration could promote the Hg(0) removal efficiency. However, when increasing the NO concentration to 300 ppm, a slightly inhibitive effect of NO was observed. In the presence of 10 ppm of HCl, greater than 95.5% Hg(0) removal efficiency was attained, which was attributed to the formation of active chlorine species on the surface. H2O presented a seriously inhibitive effect on Hg(0) removal efficiency. Repeated oxidation-regeneration cycles demonstrated that the spent Co-MF catalyst could be regenerated effectively via thermally treated at 400 °C for 2 h.

Abstract  Azanone (HNO, nitroxyl) is a highly reactive and short-lived compound with intriguing and highly relevant properties. It has been proposed to be a reaction intermediate 60 in several chemical reactions and an in vivo, endogenously produced key metabolite and/or signaling molecule. In addition, its donors have important pharmacological properties. Therefore, given its relevance and elusive nature (it reacts with itself very quickly), the development of reliable analytical methods for quantitative HNO detection is in high demand for the advancement of future research in this area. During the past few years, several methods were developed that rely on chemical reactions followed by mass spectrometry, high-performance liquid chromatography, UV-vis, or fluorescence-trapping-based methodologies. In this work, our recently developed HNO-sensing electrode, based on the covalent attachment of cobalt(II) 8,10,15,20-tetrakis[3-(p-acetylthiopropoxy)phenyl] porphyrin [Co(P)] to a gold electrode, has been thoroughly characterized in terms of sensibility, accuracy, time-resolved detection, and compatibility with complex biologically compatible media. Our results show that the Co(P) electrode: (i) allows time-resolved detection and kinetic analysis of the electrode response (the underlying HNO-producing reactions can be characterized) (ii) is able to selectively detect and reliably quantify HNO in the 1-1000 nM range, and (iii) has good biological media compatibility (including cell culture), displaying a lack of spurious signals due to the presence of O-2, NO, and other reactive nitrogen and oxygen species. In summary, the Co(P) electrode is to our knowledge the best prospect for use in studies investigating HNO-related chemical and biological reactions.

Abstract  We investigated Arctic plants to determine if they have a specific mechanism enabling them to adapt to extreme environments because they are subject to such conditions throughout their life cycles. Among the cell defense systems of the Arctic mouse-ear chickweed Cerastium arcticum, we identified a stress-responsive dehydrin gene CaDHN that belongs to the SK5 subclass and contains conserved regions with one S segment at the N-terminus and five K segments from the N-terminus to the C-terminus. To investigate the molecular properties of CaDHN, the yeast Saccharomyces was transformed with CaDHN. CaDHN-expressing transgenic yeast (TG) cells recovered more rapidly from challenge with exogenous stimuli, including oxidants (hydrogen peroxide, menadione, and tert-butyl hydroperoxide), high salinity, freezing and thawing, and metal (Zn(2+)), than wild-type (WT) cells. TG cells were sensitive to copper, cobalt, and sodium dodecyl sulfate. In addition, the cell survival of TG cells was higher than that of WT cells when cells at the mid-log and stationary stages were exposed to increased ethanol concentrations. There was a significant difference in cultures that have an ethanol content >16 %. During glucose-based batch fermentation at generally used (30 °C) and low (18 °C) temperatures, TG cells produced a higher alcohol concentration through improved cell survival. Specifically, the final alcohol concentrations were 13.3 and 13.2 % in TG cells during fermentation at 30 and 18 °C, respectively, whereas they were 10.2 and 9.4 %, respectively, in WT cells under the same fermentation conditions. An in vitro assay revealed that purified CaDHN acted as a reactive oxygen species scavenger by neutralizing H2O2 and a chaperone by preventing high temperature-mediated catalase inactivation. Taken together, our results show that CaDHN expression in transgenic yeast confers tolerance to various abiotic stresses by improving redox homeostasis and enhances fermentation capacity, especially at low temperatures (18 °C).

Abstract  Northern peatlands are increasingly threatened by climate change and industrial activities. This study examined the impact of simulated droughts on pore water chemistry at six peatlands in Sudbury, Ontario, that differ in copper (Cu), nickel (Ni) and cobalt (Co) contamination, including a site that had been previously limed. All sites responded similarly to simulated drought: pore water pH declined significantly following the 30 day drought and the decline was greater following the 60 day drought treatment. The decline in pore water pH was due to increasing sulphate concentrations, whereas nitrate increased more in the 60 day drought treatment. Decreases in pH were accompanied by large increases in Ni and Co that greatly exceeded provincial water quality guidelines. In contrast, dissolved organic carbon (DOC) concentrations decreased significantly following drought, along with concentrations of Cu and Al, which are strongly complexed by organic acids.

Abstract  A method for electrochemical deposition of a two-component Ce1-xZrxO2 system on stainless steel substrate that is attractive from catalytic point of view is proposed. As reported in the literature, it is a promising carrier layer for the production of catalytic converters for purification of exhaust gases containing NOx and CO. This system is modified by electrodeposition of a thin film of cobalt oxide over it. A series of samples of the Ce1-xZrxO2/COxOy system was produced with various concentrations and proportions of the components. These samples are characterized by XRD, SEM, EDS, XPS and PCC (partial electrocatalytic curves) of CO oxidation and of NOx reduction. Based on the obtained results, it has been concluded that the electrodeposited two-component Ce1-xZrxO2 system is a solid solution with composition, structure, and physicochemical properties that make it suitable for use as active phase carrier for catalytic oxidation of CO and reduction of NOx.

Abstract  A removal of different metals using both acid reflux and the microwave assisted digestion method was investigated. As a carbon material multi-walled carbon nanotubes synthetized on iron, cobalt and iron-cobalt catalysts without support were applied. The amount of metal particles after purification was determined using a thermobalance and it was found that microwave heating improved the efficiency of purification, especially at elevated pressure. Similar removal degrees of catalyst particles were achieved using the acid reflux method for 24 h and microwave heating for 15 min at 20 at regardless of the kind of metal. Raman measurements indicate that all the obtained samples were characterized with a high ratio of peak IG/ID intensities which confirms a good quality of the materials. (C) 2014 Published by Elsevier B.V.

Abstract  A series of 3,4-dihydropyrimidin-2(1H)-one(thione) derivatives was synthesized using Co(NO3)(2)center dot 6H(2)O in solvent-free condition. Avoiding organic solvents during the chemical reactions leading to an economic approach is effective. The reaction is characterized by high efficiency, short reaction time, high yields, simple experimental procedure, availability of catalyst and environmentally friendly reaction conditions.

Abstract  In the chemical-induced transition of FeCl2 solution, the FeOOH/Mg(OH)(2) precursor was transformed into spinel structured gamma-Fe2O3 crystallites, coated with a FeCl3 center dot 6H(2)O layer. CoCl2 surface modified gamma-Fe2O3 nanoparticles were prepared by adding Co(NO3)(2) during the synthesis. CoFe2O4 modified gamma-Fe2O3 nanoparticles were prepared by adding NaOH during the surface modification with Co(NO3)(2). The CoFe2O4 layer grew epitaxially on the gamma-Fe2O3 crystallite to form a composite crystallite, which was coated by CoCl2 center dot 6H(2)O. The composite could not be distinguished using X-ray diffraction or transmission electron microscopy, since CoFe2O4 and gamma-Fe2O3 possess similar spinel structures and lattice constants. Xray photoelectron spectroscopy was used to distinguish them. The saturation magnetization and coercivity of the spinel structured gamma-Fe2O3-based nanoparticles were related to the grain size. (C) 2014 Elsevier B.V. All rights reserved.

Abstract  Five metal complexes of 2-methylisothiazol-3(2H)-one (MIO), [Co(III)(NH3)5(MIO)](3+), [Ru(II)(NH3)5(MIO)](2+), [Ru(III)(NH3)5(MIO)](3+), [Pt(II)Cl3(MIO)](-), and trans-[U(VI)O2(NO3)2(MIO)2], were synthesized, and their structures were determined by single-crystal X-ray crystallography. MIO is an ambidentate ligand and coordinates to metal centers through its oxygen atom in the cobalt(III), ruthenium(III), and uranium(VI) complexes and through its sulfur atom in the ruthenium(II) and platinum(III) complexes. This result suggests that MIO shows preferential behavior on its donating atoms. We also studied the electron-donor abilities of the oxygen and sulfur atoms of MIO. Various physical measurements on the conjugate acid of MIO and the MIO complexes allowed us to determine an acid dissociation constant (pKa) and donor number (DN) for the oxygen atom of MIO and Lever's electrochemical parameter (EL) and a relative covalency parameter (kL) for the sulfur atom.

Abstract  In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe2O4 and ferrimagnetic oxide/ferromagnetic metal CoFe2O4/CoFe2 nanocomposite. The latter compound is a good system to study hard ferrimagnet/soft ferromagnet exchange coupled. Two steps were followed to synthesize the bimagnetic CoFe2O4/CoFe2 nanocomposite: (i) first, preparation of CoFe2O4 nanoparticles using a simple hydrothermal method, and (ii) second, reduction reaction of cobalt ferrite nanoparticles using activated charcoal in inert atmosphere and high temperature. The phase structures, particle sizes, morphology, and magnetic properties of CoFe2O4 nanoparticles were investigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) with applied field up to 3.0 kOe at room temperature and 50 K. The mean diameter of CoFe2O4 particles is about 16 nm. Mossbauer spectra revealed two sites for Fe3+. One site is related to Fe in an octahedral coordination and the other one to the Fe3+ in a tetrahedral coordination, as expected for a spinel crystal structure of CoFe2O4. TEM measurements of nanocomposite showed the formation of a thin shell of CoFe2 on the cobalt ferrite and indicate that the nanoparticles increase to about 100 nm. The magnetization of the nanocomposite showed a hysteresis loop that is characteristic of exchange coupled systems. A maximum energy product (BH)(max) of 1.22 MGOe was achieved at room temperature for CoFe2O4/CoFe2 nanocomposites, which is about 115% higher than the value obtained for CoFe2O4 precursor. The exchange coupling interaction and the enhancement of product (BH)(max) in nanocomposite CoFe2O4/CoFe2 are discussed. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Novel characteristics for the Fe(x)Co(y) alloys have been obtained when these compounds were synthesized in the form of nanofibers encapsulated in a graphite shell. The prepared nanofibers reveal good semiconducting features as a thin film from the prepared nanofibers supported on a graphite disk and could be utilized as a diode with good rectifying behaviour. Magnetic properties study showed that the introduced nanofibers are magnetically clean as very low remanent magnetizations were detected; moreover the saturation magnetization is a temperature-independent property. Optical properties study indicated that these nanofibers have band gap energies of 4.73 and 5.43 eV. Fe(x)Co(y) bimetallic alloys could be produced in the form of nanofibers encapsulated in a graphite shell by calcination of electrospun nanofiber mats composed of poly(vinyl alcohol), ferrous acetate and cobalt acetate tetrahydrate in an argon atmosphere at 750 degrees C. The composition of the nanofibers could be adjusted by controlling the concentration of the original electrospun solution; two formulations have been prepared: FeCo and FeCo(2.7). Transmission electron microscopy indicated that the thickness of the graphite shell enveloping the obtained nanofibers is similar to 10 nm. A graphite disk possessing on its surface a well attached thin film from the introduced nanofibers could be successfully prepared when a diskette made of poly(acrylonitrile) was used as a collector during the electrospinning process. The introduced methodology is effective, simple and can be exploited to produce different metallic alloys nanofibers.