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Sample records for cobalt chromium palladium

  1. Metallurgical characterization of new palladium-containing cobalt chromium and nickel chromium alloys

    Science.gov (United States)

    Puri, Raghav

    Recently introduced to the market has been an entirely new subclass of casting alloy composition whereby palladium (˜25 wt%) is added to traditional base metal alloys such as CoCr and NiCr. Objectives. The purpose of this study was to evaluate the microstructure and Vickers hardness of two new CoPdCr and one new NiPdCr alloy and compare them to traditional CoCr and NiCr alloys. Methods. The casting alloys investigated were: CoPdCr-A (Noble Crown NF, The Argen Corporation), CoPdCr-I (Callisto CP+, Ivoclar Vivadent), NiPdCr (Noble Crown, Argen), CoCr (Argeloy N.P. Special, Argen), and NiCr (Argeloy N.P. Star, Argen). As-cast cylindrical alloy specimens were mounted in epoxy resin and prepared with standard metallographic procedures, i.e. grinding with successive grades of SiC paper and polishing with alumina suspensions. The alloys were examined with an optical microscope, SEM/EPMA, and XRD to gain insight into their microstructure, composition, and crystal structure. Vickers hardness (VHN) was measured and statistically analyzed by one way ANOVA and Tukey's HSD test (alpha=0.05). Results. Optical microscopy showed a dendritic microstructure for all alloys. The Pd-containing alloys appear to possess a more complex microstructure. SEM/EPMA showed Cr to be rather uniformly distributed in the matrix with palladium tending to be segregated apart from Mo and Ni or Co. Areas of different composition may explain the poor electrochemical results noted in previous studies. XRD suggested the main phase in the Ni-containing solutions was a face centered cubic Ni solid solution, whereas the CoCr exhibited a hexagonal crystal structure that was altered to face centered cubic when Pd was included in the composition. For Vickers hardness, the Co-containing alloys possessed a greater hardness than the Ni-containing alloys. However, the incorporation of Pd in CoCr and NiCr had only a slight effect on microhardness. Conclusion. Overall, the inclusion of palladium increases the

  2. Nickel, cobalt, chromium, palladium and gold induce a mixed Th1- and Th2-type cytokine response in vitro in subjects with contact allergy to the respective metals.

    Science.gov (United States)

    Minang, J T; Areström, I; Troye-Blomberg, M; Lundeberg, L; Ahlborg, N

    2006-12-01

    Nickel (Ni), the main cause of contact allergy to metals, induces in vitro production of both Th1- and Th2-type cytokines in peripheral blood mononuclear cells (PBMC) from allergic subjects. Because the knowledge of the cellular immune response to other metals involved in contact allergy has been limited, we investigated the cytokine profile induced by Ni, cobalt (Co), chromium (Cr), palladium (Pd) and gold (Au) in PBMC from patients with patch test reactivity to the respective metals. PBMC from patients with patch test reactivity to Ni, Co, Cr, Au and/or Pd (n = 31) and non-allergic controls (n = 5) were stimulated in vitro with corresponding metal salts. Th1- [interleukin (IL)-2 and interferon (IFN)-gamma] and Th2- (IL-4 and IL-13) type cytokine responses were measured by enzyme-linked immunospot (ELISpot) and/or enzyme-linked immunosorbent assay (ELISA). All metals induced a mixed Th1- and Th2-type cytokine production in PBMC from individual patients with patch test reactivity to the corresponding metal, but not in control PBMC. Significantly higher responses in the patient versus controls were found for Cr (IL-2 and IL-13), Pd (IL-2 and IL-4), Au (IL-13 and IFN-gamma) (all P reactivities to metals, respectively, were matched by the in vitro reactivity. In conclusion, our data suggest that sensitization to Co, Cr, Pd and Au results in a cellular immune response of a character similar to the mixed Th1- and Th2-type cytokine profile shown previously to be induced by Ni.

  3. Galvanic cells including cobalt-chromium alloys.

    Science.gov (United States)

    Gjerdet, N R

    1980-01-01

    Galvanic cells may be created when dentures made of cobalt-chromium alloys are placed on teeth with metallic restorations. The power of such cells was evaluated in an in vitro galvanic using amalgams, gold alloy, and nickel-chromium alloys. The amalgams and one of the nickel-chromium alloys revealed high corrosion currents when placed in contact with cobalt-chromium alloy, the conventional amalgam showing the highest values. The gold alloy and another nickel-chromium alloy exhibited low corrosion currents and they were noble with respect to cobalt-chromium.

  4. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    Science.gov (United States)

    Adzic, Radoslav; Huang, Tao

    2009-12-15

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

  5. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining a...

  6. Mechanical properties of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

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    Mirković Nemanja

    2007-01-01

    Full Text Available Background/Aim. Metal-ceramic bond strength and alloys' elastic modulus clearly determine the potential of alloy application, because the ceramic integrity during mastication depends on these two characteristics. The aim of this study was to evaluate metal-ceramic bond strength and elastic modulus of cobalt-chromium alloys in making porcelainfused- to-metal restorations, regarding the application of the most frequent nickel-chromium alloy. Methods. The research was performed as an experimental study. Six metalceramic samples were made from nickel-chromium alloy (Wiron 99 and cobalt-chromium alloy (Wirobond C, according to the manufactures manuals and instructions from ISO 9693: 1996. Three-point bending test was performed up to the ceramic fracture. The fracture load was measured on an universal testing machine (Zwick, type 1464, with cross-head speed of 0,05mm/min. Results. The results of this study confirmed the significant differences between the metal-ceramic bond strength (p < 0.01 and elastic modulus (p < 0.001 of nickel-chromium and cobalt-chromium alloys, where cobalt-chromium alloys showed higher values for both tested parameters. Conclusion. Cobalt-chromium metal-ceramic alloys can successfully replace nickel-chromium alloys, especially for fabrication of long-span metal-ceramic bridges due to the great flexural strength.

  7. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg. No...

  8. Cobalt chromium stents versus stainless steel stents in diabetic patients

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    Mahmoud Ahmed Tantawy

    2014-03-01

    Conclusions: We concluded that no significant statistical difference was found between the two stents (cobalt-chromium alloy bare metal stent versus conventional bare metal stainless steel stent in diabetic patients regarding (initial procedural success, in-hospital complications, the incidence of ISR at follow up, event-free survival at follow up.

  9. Black and green pigments based on chromium-cobalt spinels

    Energy Technology Data Exchange (ETDEWEB)

    Eliziario, Sayonara A., E-mail: sayonaraea@iq.unesp.br [Departamento de Fisico-Quimica, Instituto de Quimica, UNESP - Univ Estadual Paulista, Araraquara, SP (Brazil); Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Andrade, Jeferson M. de [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Lima, Severino J.G. [Departamento de Engenharia Mecanica, CT, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Paskocimas, Carlos A. [Universidade Federal do Rio Grande do Norte, CT, Natal, RN (Brazil); Soledade, Luiz E.B. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil); Hammer, P.; Longo, E. [Departamento de Fisico-Quimica, Instituto de Quimica, UNESP - Univ Estadual Paulista, Araraquara, SP (Brazil); Souza, Antonio G.; Santos, Ieda M.G. [Departamento de Quimica, CCEN, Universidade Federal da Paraiba, Campus I, Joao Pessoa, PB (Brazil)

    2011-09-15

    Highlights: {yields} Co(Co{sub 2-x}Cr{sub x})O{sub 4} powders with different chromium concentrations (x = 0, 0.25 and 1) were prepared by the polymeric precursor method. {yields} Co(CoCr)O{sub 4} and Co(Co{sub 1.75}Cr{sub 0.25})O{sub 4} displayed a dark color and CoCr{sub 2}O{sub 4} was green. {yields} The colors were related to the different oxidation states of Cr and Co. {yields} Cobalt enrichment result in an increasing presence of Co(III) and a decrease amount of Cr(VI). - Abstract: Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co{sub 2-x}Cr{sub x})O{sub 4} powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 deg. C. These powders were characterized by X-ray diffraction, infrared spectroscopy, colorimetry, UV-vis absorption and X-ray photoelectron spectroscopies. Even with the addition of chromium, the XRD patterns revealed that all powders crystallize in a single spinel cubic structure. The spinels with higher cobalt amount, Co(CoCr)O{sub 4} and Co(Co{sub 1.75}Cr{sub 0.25})O{sub 4}, displayed a dark color, without the Co{sup 3+} reduction observed in Co{sub 3}O{sub 4} between 900 and 950 deg. C. The spinel with higher chromium amount, CoCr{sub 2}O{sub 4}, was green. The colors were directly related to the occupation of tetrahedral and octahedral sites by the chromophores, as well as to the different oxidation states of chromium and cobalt. The different optical band gap values estimated from UV-vis spectra suggested the existence of intermediary energy levels within the band gap. X-ray photoelectron spectroscopy confirmed an increasing presence of Co(III) and a decreasing amount of Cr(VI) with cobalt enrichment.

  10. Chromium Substituted Cobalt Ferrites by Glycine-Nitrates Process

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    Dana Gingasu

    2015-12-01

    Full Text Available Chromium substituted cobalt ferrites (CoFe2–xCrxO4, 0 ≤ x ≤ 2 were synthesized through solution combustion method using glycine as fuel, named glycine-nitrates process (GNP. As evidenced by X-ray diffraction data (XRD, single cubic spinel phase was formed for all CoFe2–xCrxO4 (0 ≤ x ≤ 2 series. The cubic lattice parameter (a decreases with increasing chromium content. Room temperature 57Fe Mössbauer spectra revealed the Fe3+ and Cr3+ site occupancy, the local hyperfine magnetic fields and the substitution of Fe3+ by Cr3+ in the lattice. Scanning electron microscopy (SEM showed a refinement of particle size with the increase of Cr3+ content. Magnetic measurements from 5 K to 120 K have shown a dropping in the saturation magnetization as the chromium content increases. This behaviour has been explained in terms of substitution of Fe3+ by Cr3+ in the cubic lattice of cobalt ferrite.

  11. Cobalt allergy: suitable test concentration, and concomitant reactivity to nickel and chromium.

    Science.gov (United States)

    Lidén, Carola; Andersson, Niklas; Julander, Anneli; Matura, Mihály

    2016-06-01

    Cobalt allergy is frequent, but knowledge about exposure is limited. The patch test concentration and relevance of positive reactions are sometimes questioned. To assess the suitability of cobalt 1% versus 0.5% for patch testing, and to analyse the co-occurrence of allergy to cobalt, chromium, and nickel. Consecutive dermatitis patients (n = 656) were patch tested with cobalt chloride 0.5% and 1%, potassium dichromate 0.5%, and nickel sulfate 5%, all in petrolatum. Reactions were assessed on day (D)3, and on D6 or D7, and the reactivity and development of reactions were analysed. Allergy to any metal was shown in 31% of patients, allergy to cobalt in 14%, allergy to chromium in 7%, and allergy to nickel in 20%. A significant proportion (37%) of cobalt allergy cases were missed by cobalt 0.5% versus 1%, whereas the reactivity profiles were similar. Cobalt allergy was solitary, without concomitant allergy to chromium or nickel, in 50% of patients. Cobalt chloride 1% pet. is more suitable for patch testing than 0.5%. Solitary cobalt allergy is as frequent as concomitant allergy to cobalt and nickel or chromium. Sources of skin exposure to metals need to be identified for prevention of contact allergy. This is, owing to large knowledge gaps, particularly demanding for cobalt. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Levitation calorimetry. IV - The thermodynamic properties of liquid cobalt and palladium.

    Science.gov (United States)

    Treverton, J. A.; Margrave, J. L.

    1971-01-01

    Some of the thermodynamic properties of liquid cobalt and palladium investigated by means of levitation calorimetry are reported and discussed. The presented data include the specific heats and heats of fusion of the liquid metals, and the emissivities of the liquid metal surfaces.

  13. Synthesis and characterization of palladium and palladium-cobalt nanoparticles on Vulcan XC-72R for the oxygen reduction reaction.

    Science.gov (United States)

    Arroyo-Ramírez, Lisandra; Montano-Serrano, Rubenier; Luna-Pineda, Tatiana; Román, Félix R; Raptis, Raphael G; Cabrera, Carlos R

    2013-11-27

    A single-source approach was used to synthesize bimetallic nanoparticles on a high-surface-area carbon-support surface. The synthesis of palladium and palladium-cobalt nanoparticles on carbon black (Vulcan XC-72R) by chemical and thermal reduction using organometallic complexes as precursors is described. The electrocatalysts studied were Pd/C, Pd2Co/C, and PdCo2/C. The nanoparticles composition and morphology were characterized using inductively coupled plasma mass spectrophotometer (ICP-MS), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray fluorescence spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. Electrocatalytic activity towards the oxygen reduction reaction (ORR) and methanol tolerance in oxygen-saturated acid solution were determined. The bimetallic catalyst on carbon support synthetized by thermal reduction of the Pd2Co precursor has ORR electrocatalytic activity and a higher methanol tolerance than a Pt/C catalyst.

  14. Fabrication and buckling behavior of polycrystalline palladium, cobalt, and rhodium nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Jahed, Zeinab [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Jin, Sumin [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Burek, Michael J. [Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Tsui, Ting Y., E-mail: tttsui@uwaterloo.ca [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer Pd, Co, and Rh nano-pillars with diameter of {approx}130 nm were fabricated by using novel electron beam lithography and electroplating techniques. Black-Right-Pointing-Pointer Uniaxial compression load and displacement responses of the nanopillars were characterized. Black-Right-Pointing-Pointer Pd nano-pillars have the highest fracture toughness followed by Co and Rh pillars. Black-Right-Pointing-Pointer Tangent moduli of the three materials were extracted from the experimental results. - Abstract: Novel fabrication techniques were developed to manufacture polycrystalline palladium, cobalt, and rhodium nanopillars with diameters of approximately 130 nm. These nanostructures have length-to-radius ratios in the range of 4 and 20. Using uniaxial nano-compression techniques, the buckling behaviors of the produced nanopillars were characterized and critical buckling loads were extracted. The tangent moduli, which were extracted from plots of critical buckling load as a function of effective specimen cross-sectional area, of palladium, cobalt, and rhodium nanopillars are 90 {+-} 6 GPa, 175 {+-} 9 GPa, and 375 {+-} 23 GPa, respectively. As expected, these calculated values are slightly smaller than the bulk polycrystalline elastic moduli for all three materials. Post compression scanning electron microscope images revealed ductile behavior for palladium nanostructures, while cobalt and rhodium specimens failed by fracture.

  15. Compliance of a cobalt chromium coronary stent alloy – the COVIS trial

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    Schwinger Robert HG

    2005-10-01

    Full Text Available Abstract Background Cobalt chromium coronary stents are increasingly being used in percutaneous coronary interventions. There are, however, no reliable data about the characteristics of unfolding and visibility of this stent alloy in vivo. The aim of this study is to compare cobalt chromium coronary stents with conventional stainless steel stents using intracoronary ultrasound. Methods Twenty de novo native coronary stenoses ≤ 20 mm in length (target vessel reference diameter ≥ 2.5 and ≤ 4.0 mm received under sequential intracoronary ultrasound either a cobalt chromium stent (Multi-Link Vision®; n = 10 or a stainless steel stent (Multi-Link Zeta®; n = 10. Results For optimal unfolding, the cobalt chromium stent requires a higher balloon deployment pressure (13.90 ± 2.03 atm than the stainless steel stent (11.50 ± 2.12 atm. Furthermore, the achieved target vessel diameter of the cobalt chromium stent (Visibility-Index QCA/IVUS Multi-Link Vision®1.13 / Multi-Link Zeta® 1.04 is more easily overrated by Quantitative Coronary Analysis. Conclusion These data indicate that stent material-specific recommendations for optimal implantation pressure and different stent material with an equal design should both be considered in interpreting QCA-analysis.

  16. Metal-on-metal bearings in total hip arthroplasties : Influence of cobalt chromium ions on bacterial growth and biofilm formation

    NARCIS (Netherlands)

    Hosman, Anton H.; van der Mei, Henny C.; Bulstra, Sjoerd K.; Busscher, Henk J.; Neut, Danielle

    2009-01-01

    Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm form

  17. Cobalt to Chromium Ratio is Not a Key Marker for Adverse Local Tissue Reaction (ALTR) in Metal on Metal Hips.

    Science.gov (United States)

    Fehring, Thomas K; Carter, Joshua L; Fehring, Keith A; Odum, Susan M; Griffin, William L

    2015-09-01

    The diagnosis of adverse local tissue reaction (ALTR) after metal-on-metal total hip arthroplasty (MoMTHA) presents a significant challenge. No single biomarker is specific for ALTR. The purpose of this study was to determine if the ratio of cobalt to chromium ions is useful for diagnosing ALTR in MoMTHA. In 89 bearing-related revision THAs, preoperative cobalt and chromium ion levels were compared to an intraoperative soft tissue damage grading scale. The average cobalt to chromium ratio was 2.96 (0-20). There was no correlation between the tissue scale and the cobalt to chromium ratio (R=0.095; P=0.41). Many variables affecting ion production/excretion mitigate the use of the ion ratio. The cobalt to chromium ratio is not a predictive biomarker for ALTR in MoMTHA. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Differences in proliferation, differentiation, and cytokine production by bone cells seeded on titanium-nitride and cobalt-chromium-molybdenum surfaces.

    Science.gov (United States)

    van Hove, Ruud P; Nolte, Peter A; Semeins, Cornelis M; Klein-Nulend, Jenneke

    2013-08-01

    Titanium-nitride coating is used to improve cobalt-chromium-molybdenum implant survival in total knee arthroplasty, but its effect on osteoconduction is unknown. Chromium and cobalt ions negatively affect the growth and metabolism of cultured osteoblasts while enhancing osteoclastogenic cytokine production. Therefore, it was hypothesized that a titanium-nitride surface would enhance osteoblast proliferation and/or differentiation and reduce osteoclastogenic cytokine production compared with a cobalt-chromium-molybdenum surface. MC3T3-E1 osteoblasts showed increased proliferation and decreased differentiation on titanium-nitride, while cytokine interleukin-6 production was higher on porous cobalt-chromium-molybdenum (p cobalt-chromium-molybdenum surface.

  19. Skin deposition of nickel, cobalt, and chromium in production of gas turbines and space propulsion components.

    Science.gov (United States)

    Julander, Anneli; Skare, Lizbet; Mulder, Marie; Grandér, Margaretha; Vahter, Marie; Lidén, Carola

    2010-04-01

    Skin exposure to nickel, cobalt, and chromium may cause sensitization and allergic contact dermatitis and it is known that many alloys and platings may release significant amounts of the metals upon contact with skin. Occupational exposure to these sensitizing metals has been studied in different settings with regards to airborne dust and different biological end points, but little is known about deposition on skin from airborne dust and direct contact with materials containing the metals. In this study, skin deposition was studied in 24 workers in an industry for development and manufacturing of gas turbines and space propulsion components. The workers were employed in three departments, representing different exposure scenarios: tools sharpening of hard metal items, production of space propulsion structures, and thermal application of different metal-containing powders. A novel acid wipe sampling technique was used to sample metals from specific skin surfaces on the hands and the forehead of the workers. Total amounts of nickel, cobalt, and chromium were measured by inductively coupled plasma mass spectrometry. The result showed that nickel, cobalt, and chromium could be detected on all skin surfaces sampled. The highest level of nickel was 15 microg cm(-2) h(-1), the highest for cobalt was 4.5 microg cm(-2) h(-1), and for chromium 0.6 microg cm(-2) h(-1). The three departments had different exposures regarding the metals. The highest levels of nickel on the skin of the workers were found in the thermal applications department, cobalt in the tools sharpening department, and chromium in the space propulsion components department. In conclusion, the workers' exposure to the metals was more likely to come from direct skin contact with items, rather than from airborne dust, based on the fact that the levels of metals were much higher on the fingers than on the back side of the hands and the forehead. The skin exposure levels of nickel and cobalt detected are judged

  20. Growth of magnetic cobalt/chromium nano-arrays by atom-optical lithography

    Energy Technology Data Exchange (ETDEWEB)

    Atoneche, F; Malik, D; Kirilyuk, A; Toonen, A J; Etteger, A F van; Rasing, Th, E-mail: f.atoneche@science.ru.nl [Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ, Nijmegen (Netherlands)

    2011-07-06

    Arrays of magnetic cobalt/chromium (Co-Cr) nanolines are grown by depositing an atomic beam of Co-Cr alloy through a laser standing wave (SW) at {lambda}/2 = 212.8 nm onto a substrate. During deposition, only the chromium atoms are resonantly affected by the optical potential created by the SW, causing a periodic modulation of the chromium concentration and consequently of the magnetic properties. Magnetic force microscopy and magneto-optical Kerr effect studies reveal a patterned magnetic structure on the substrate surface.

  1. Growth of magnetic cobalt/chromium nano-arrays by atom-optical lithography

    Science.gov (United States)

    Atoneche, F.; Malik, D.; Kirilyuk, A.; Toonen, A. J.; van Etteger, A. F.; Rasing, Th

    2011-07-01

    Arrays of magnetic cobalt/chromium (Co-Cr) nanolines are grown by depositing an atomic beam of Co-Cr alloy through a laser standing wave (SW) at λ/2 = 212.8 nm onto a substrate. During deposition, only the chromium atoms are resonantly affected by the optical potential created by the SW, causing a periodic modulation of the chromium concentration and consequently of the magnetic properties. Magnetic force microscopy and magneto-optical Kerr effect studies reveal a patterned magnetic structure on the substrate surface.

  2. Effects of cobalt and chromium ions on lymphocyte migration.

    Science.gov (United States)

    Baskey, Stephen J; Lehoux, Eric A; Catelas, Isabelle

    2017-04-01

    A T cell-mediated hypersensitivity reaction has been reported in some patients with CoCrMo-based implants. However, the role of cobalt and chromium ions in this reaction remains unclear. The objective of the present study was to analyze the effects of Co(2+) and Cr(3+) in culture medium, as well as the effects of culture supernatants of macrophages exposed to Co(2+) or Cr(3+) , on the migration of lymphocytes. The release of cytokines/chemokines by macrophages exposed to Co(2+) and Cr(3+) was also analyzed. The migration of murine lymphocytes was quantified using the Boyden chamber assay and flow cytometry, while cytokine/chemokine release by J774A.1 macrophages was measured by ELISA. Results showed an ion concentration-dependent increase in TNF-α and MIP-1α release and a decrease in MCP-1 and RANTES release. Migration analysis showed that the presence of Co(2+) (8 ppm) and Cr(3+) (100 ppm) in culture medium increased the migration of T lymphocytes, while it had little or no effect on the migration of B lymphocytes, suggesting that Co(2+) and Cr(3+) can stimulate the migration of T but not B lymphocytes. Levels of T lymphocyte migration in culture medium containing Co(2+) or Cr(3+) were not statistically different from those in culture supernatants of macrophages exposed to Co(2+) or Cr(3+) , suggesting that the effects of the ions and chemokines were not additive, possibly because of ion interference with the chemokines and/or their cognate receptors. Overall, results suggest that Co(2+) and Cr(3+) are capable of stimulating the migration of T (but not B) lymphocytes in the absence of cytokines/chemokines, and could thereby contribute to the accumulation of more T than B lymphocytes in periprosthetic tissues of some patients with CoCrMo-based implants. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:916-924, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  3. Isolation, identification and characterization of indigenous fungi for bioremediation of hexavalent chromium, nickel and cobalt

    Science.gov (United States)

    Hernahadini, Nelis; Suhandono, Sony; Choesin, Devi N.; Chaerun, Siti K.; Kadarusman, Ade

    2014-03-01

    Waste from nickel mining of Sorowako in South Sulawesi contains hexavalent chromium, nickel and cobalt metals in high concentration and may have a negative impact to the environment. Common waste treatment systems such as chemical treatment using a reducing reagent may still have a negative impact. Bioremediation using fungi or bacteria becomes more popular because it is an environmentally friendly alternative. The purposes of this study are to isolate and identify indigenous fungi that are resistant to heavy metals (hexavalent chromium, nickel, and cobalt) and are capable of reducing the concentration of metals in mining wastes. Ten fungal isolates were successfully isolated from the soils and pond sediments in the area of nickel mining in Sorowako. Selection of superior isolate was carried out by growing all the isolates on PDA medium, which contained all of the three metals. One superior isolate was identified to be able to grow on medium with concentrations of 6400 ppm hexavalent chromium, 200 ppm nickel and 50 ppm cobalt. Molecular identification and phylogenetic studies of the isolate using fungal PCR primers developed to amplify the ITS (internal transcribed spacer) region showed that the isolate sequence was very close to Trichoderma atroviride with 99.8% similarity. Optimum incubation time for the uptake of hexavalent chromium was 3 days, nickel and cobalt was 5 days, respectively, with an optimum pH of 4.

  4. Neuropsychiatric symptoms following metal-on-metal implant failure with cobalt and chromium toxicity.

    Science.gov (United States)

    Green, Ben; Griffiths, Emily; Almond, Solomon

    2017-01-24

    There were at least 31,171 metal-on-metal (MoM) hip implants in the UK between 2003 and 2011. Some of these were subject to failure and widescale recalls and revisions followed. This is a presentation of ten cases (mean age 60 years) where we evaluated neuropsychiatric morbidity following metal-on-metal hip implant failure and revision. Implants were ASR total hip replacement (acetabular implant, taper sleeve adaptor and unipolar femoral implants) performed between 2005 and 2009. This case series describes, for the first time, neuropsychiatric complications after revision where there has been cobalt and chromium toxicity. Pre-revision surgery, nine patients had toxic levels of chromium and cobalt (mean level chromium 338 nmol/l, mean cobalt 669.4 nmol/l). Depression assessment showed 9 of 9 respondents fulfilled the BDI criteria for depression and 3 of these were being treated. 7 of 9 patients showing short term memory deficit with mean mini mental state examination score of 24.2. The normal population mean MMSE for this group would be expected to be 28 with cobalt and chromium metallosis following MoM implant failure. Larger studies of neurocognitive effects are indicated in this group. There may be implications for public health.

  5. Do cobalt and chromium levels predict osteolysis in metal-on-metal total hip arthroplasty?

    Science.gov (United States)

    Renner, Lisa; Schmidt-Braekling, Tom; Faschingbauer, Martin; Boettner, Friedrich

    2016-12-01

    Serum metal ions are part of the regular follow-up routine of patients with metal-on-metal total hip arthroplasties (MoM-THA). Increased cobalt levels have been suggested to indicate implant failure and corrosion. (1) Is there a correlation between the size of the osteolysis measured on a CT scan and metal ion levels? (2) Can metal ion levels predict the presence of osteolysis in MoM-THA? (3) Are cobalt and chromium serum levels or the cobalt-chromium-ratio diagnostic for osteolysis? CT scans of patients (n = 75) with a unilateral MoM-THA (Birmingham Hip System, Smith & Nephew, TN, USA) implanted by a single surgeon were reviewed to determine the presence of osteolysis. Statistical analysis was performed to detect its association with metal ion levels at the time of the imaging exam. The incidence of osteolysis was the same in men and women (35.6 vs 35.7 %). The cobalt-chromium-ratio correlates with the size of the osteolysis on the CT scan and the femoral component size in the overall study population (p = 0.050, p = 0.001) and in men (p = 0.002, p = 0.001) but not in women (p = 0.312, p = 0.344). The AUC for the cobalt-chromium-ratio to detect osteolysis was 0.613 (p = 0.112) for the overall population, 0.710 for men (p = 0.021) and 0.453 (p = 0.684) for women. The data suggest that a cut off level of 1.71 for the cobalt-chromium-ratio has a sensitivity of 62.5 % and specificity of 72.4 % to identify male patients with osteolysis. The disproportional increase of cobalt over chromium, especially in male patients with large component sizes can not be explained by wear alone and suggests that other processes (corrosion) might contribute to metal ion levels and might be more pronounced in patients with larger component sizes.

  6. Establishing human heart chromium, cobalt and vanadium concentrations by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Day, Patrick L; Eckdahl, Steven J; Maleszewski, Joseph J; Wright, Thomas C; Murray, David L

    2017-05-01

    Chromium, cobalt, and vanadium are used in metallic joint prosthesis. Case studies have associated elevated heart tissue cobalt concentrations with myocardial injury. To document the long term heart metal ion concentrations, a validated inductively coupled plasma mass spectroscopy (ICP-MS) method was needed. The method utilized a closed-vessel microwave digestion system to digest the samples. An ICP-MS method utilizing Universal Cell Technology was used to determine our target analyte concentrations. Accuracy was verified using reference materials. Precision, sensitivity, recovery and linearity studies were performed. This method was used to establish a reference range for a non-implant containing cohort of 80 autopsy human heart tissues RESULTS: This method demonstrated an analytic measurement range of 0.5-100ng/mL for each element. Accuracy was within ±10% of target value for each element. Within-run precision for each element was below 20% CV. The chromium, vanadium and cobalt concentrations (mean±SD) were 0.1523±0.2157μg/g, 0.0094±0.0211μg/g and 0.1039±0.1305μg/g respectively in 80 non-implant containing human heart tissue samples. This method provides acceptable recovery of the chromium, cobalt and vanadium in heart tissue; allowing assessment of the effects of metallic joint prosthesis on myocardial health. Copyright © 2017 Elsevier GmbH. All rights reserved.

  7. Analysis of cobalt, tantalum, titanium, vanadium and chromium in tungsten carbide by inductively coupled plasma-optical emission spectrometry

    CSIR Research Space (South Africa)

    Archer, M

    2003-12-01

    Full Text Available Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to measure the concentrations of cobalt, tantalum, titanium, vanadium and chromium in solutions of tungsten carbide. The main advantage of the method described here lies...

  8. Effect of precursor nature on the performance of palladium-cobalt electrocatalysts for direct methanol fuel cells

    Science.gov (United States)

    Serov, Alexey; Nedoseykina, Tatyana; Shvachko, Oleg; Kwak, Chan

    The performance of platinum-free palladium-cobalt catalysts in oxygen reduction was investigated for a direct methanol fuel cell. The dependence of catalytic activity on precursor nature was determined for two classes of precursors; namely, palladium chloride and palladium nitrate. The nitrate precursor exhibits much higher catalytic performance than the chloride precursor. X-ray absorption fine structure (XAFS) spectra indicate that the structure of palladium catalyst prepared from nitrate is much closer to Pd 3Co structure that can explain high catalytic activity. The MEA prepared from the nitrate catalyst achieved the peak power density of 125 mW cm -2, which is much higher than 19 mW cm -2 measured on the cell prepared from the chloride catalyst.

  9. Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander [Institute of Physics, Faculty of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, Piastów 48, 70-311 Szczecin (Poland); Adamski, Paweł; Moszyński, Dariusz [Institute of Inorganic Chemical Technology and Environment Engineering, West Pomeranian University of Technology, Szczecin, Pułaskiego 10, 70-322 Szczecin (Poland)

    2016-09-15

    Four nanocomposites containing mixed phases of Co{sub 3}Mo{sub 3}N and Co{sub 2}Mo{sub 3}N doped with chromium have been prepared. A linear fit is found for relation between Co{sub 2}Mo{sub 3}N and chromium concentrations. The magnetization in ZFC and FC modes at different temperatures (2–300 K) and in applied magnetic fields (up to 70 kOe) have been investigated. It has been detected that many magnetic characteristics of the studied four nanocomposites correlate not with the chromium concentration but with nanocrystallite sizes. The obtained results were interpreted in terms of magnetic core-shell model of a nanoparticle involving paramagnetic core with two magnetic sublattices and a ferromagnetic shell related to chromium doping. - Highlights: • A new chromium doped mixed Co-Mn-N nanocomposites were synthesized. • Surface ferromagnetism was detected in a wide temperature range. • Core-shell model was applied to explain nanocomposites magnetism.

  10. Additive Manufacturing: A Novel Method for Fabricating Cobalt-Chromium Removable Partial Denture Frameworks.

    Science.gov (United States)

    Alifui-Segbaya, Frank; Williams, Robert John; George, Roy

    2017-06-01

    Additive manufacturing (AM) often referred to as 3D printing (3DP) has shown promise of being significantly viable in the construction of cobalt-chromium removable partial denture (RPD) frameworks. The current paper seeks to discuss AM technologies (photopolymerization processes and selective laser melting) and review their scope. The review also discusses the clinical relevance of cobalt-chromium RPD frameworks. All relevant publications in English over the last 10 years, when the first 3D-printed RPD framework was reported, are examined. The review notes that AM offers significant benefits in terms of speed of the manufacturing processes however cost and other aspects of current technologies remain a hindrance. Copyright© 2017 Dennis Barber Ltd.

  11. [Research Progress in Genotoxic Effects of Degradation Products, Cobalt, Chromium Ions and Nanoparticles from Metal-on-metal Prostheses on Cells].

    Science.gov (United States)

    Zhou, Hao; Han, Qinglin; Liu, Fan

    2015-04-01

    Cobalt or chromium alloys are the most common clinical materials of prosthesis and there have been some investigators at home and abroad have done related researches about the genotoxic effects of cobalt and chromium ions and nanoparticles. People have certain understanding about the mechanism of production of ions as well as their influence on cells. However, chromium or cobalt nanoparticles genotoxicity related research is still in its preliminary stage. In each stage, the mechanisms, from creating of the particles, through entering cells, until finally causing genotoxic, are still contained many problems to be solved. This article reviews the research progress in mechanisms of production and genotoxic effects of cobalt, chromium ions and nanoparticles.

  12. Palladium-cobalt alloy for applications in electrical engineering and electronics. New coating processes; Palladium-Kobalt-Legierung fuer Elektrotechnik/Elektronik. Neue Verfahren zur Oberflaechenbeschichtung

    Energy Technology Data Exchange (ETDEWEB)

    Abys, J.A.; Breck, G.F.; Straschil, H.K. [Lucent Technologies Electroplating Chemicals and Services, Murray Hill, NJ (United States); Boguslavsky, I. [Molex Inc., Lisle, IL (USA); Holmbom, G. [CSM Materialteknik AB, Linkoping (Sweden)

    1999-11-01

    Surface properties are particularly important in plug-and-socket connections. Hard gold and palladium-nickel compounds are the most common. Lucent Electroplating Chemicals and Services (EC and S), a company of Lucent Technologies, recently developed a palladium-cobalt compound (PallaTechPdCo) with high abrasion resistance ensuring long life. The thickness of the coating layer can be controlled accurately during galvanization, which will reduce the cost as well. [German] Gerade bei elektronischen Steckverbindungen spielt die Oberflaeche eine entscheidende Rolle. Gaengig waren seither Hartgold-Ueberzuege oder Schichten aus Palladium-Nickel-Verbindungen. Bei der Lucent Electroplating Chemicals and Services (EC and S), einem Unternehmen von Lucent Technologies, hat man nun eine Palladium-Kobalt-Verbindung (PallaTechPdCo) als Legierungsmaterial entwickelt, die gegenueber den herkoemmlichen Galvanisierungswerkstoffen entscheidende Vorteile aufweisen soll. Laut Hersteller ist diese PdCo-Legierung aufgrund ihrer hohen Abriebfestigkeit haltbarer als herkoemmliche Verbindungen und gewaehrleistet somit eine groessere Zuverlaessigkeit und Sicherheit der Produkte. Weiterhin laesst sich die Masse der aufzutragenden Schicht beim Galvanisierungsprozess exakt kontrollieren. Diese Optimierung der Leistung verringert auch die anfallenden Kosten. (orig.)

  13. Differences in proliferation, differentiation, and cytokine production by bone cells seeded on titanium-nitride and cobalt-chromium-molybdenum surfaces

    NARCIS (Netherlands)

    van Hove, R.P.; Nolte, P.A.; Semeins, C.M.; Klein-Nulend, J.

    2013-01-01

    Titanium-nitride coating is used to improve cobalt-chromium-molybdenum implant survival in total knee arthroplasty, but its effect on osteoconduction is unknown. Chromium and cobalt ions negatively affect the growth and metabolism of cultured osteoblasts while enhancing osteoclastogenic cytokine pro

  14. Corrosion behavior of tantalum-coated cobalt-chromium modular necks compared to titanium modular necks in a simulator test.

    Science.gov (United States)

    Dorn, Ulrich; Neumann, Daniel; Frank, Mario

    2014-04-01

    This study compared the corrosion behavior of tantalum-coated cobalt-chromium modular necks with that of titanium alloy modular necks at their junction to titanium-alloy femoral stem. Tests were performed in a dry assembly and two wet assemblies, one contaminated with calf serum and the other contaminated with calf serum and bone particles. Whereas the titanium modular neck tested in the dry assembly showed no signs of corrosion, the titanium modular necks tested in both wet assemblies showed marked depositions and corrosive attacks. By contrast, the tantalum-coated cobalt-chromium modular necks showed no traces of corrosion or chemical attack in any of the three assemblies. This study confirms the protective effect of tantalum coating the taper region of cobalt-chromium modular neck components, suggesting that the use of tantalum may reduce the risk of implant failure due to corrosion.

  15. Investigation of superparamagnetism in pure and chromium substituted cobalt nanoferrite

    Science.gov (United States)

    Raghasudha, M.; Ravinder, D.; Veerasomaiah, P.

    2016-12-01

    Nanostructured magnetic materials with the chemical composition CoFe2O4 and CoCr0.9Fe1.1O4 were synthesized through Citrate-gel chemical synthesis with a crystallite size of 6.5 nm and 10.7 nm respectively. Structural characterization of the samples was performed by X-ray diffraction analysis and magnetic properties were studied using Vibrating Sample Magnetometer (VSM). Magnetization measurements as a function of applied magnetic field ±10 T at various temperatures 5 K, 25 K, 310 K and 355 K were carried out. Field cooled (FC) and Zero field cooled (ZFC) magnetization measurements under a magnetic field of 100 Oe for temperature ranging from 5-400 K were studied. The blocking temperature (Tb) for both the ferrites was observed to be around 355 K. Below blocking temperature they showed ferromagnetic behavior and above which they are superparamagnetic in nature that favors their application in the biomedical field. The substitution of paramagnetic Cr3+ ions for magnetic Fe3+ ion in cobalt ferrite has resulted in a decrease in magnetization and the coercivity of the samples. CoCr0.9Fe1.1O4 nanoferrites with observed low coercivity of 338 Oe make them desirable in high frequency transformers due to their very soft magnetic behavior.

  16. The fatigue life of a cobalt-chromium alloy after laser welding.

    Science.gov (United States)

    Al-Bayaa, Nabil Jalal Ahmad; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2011-03-01

    The aim of this study was to investigate the fatigue life of laser welded joints in a commercially available cast cobalt-chromium alloy. Twenty rod shaped specimens (40 mm x 1.5 mm) were cast and sand blasted. Ten specimens were used as controls and the remaining ten were sectioned and repaired using a pulsed Nd: YAG laser welder. All specimens were subjected to fatigue testing (30N - 2Hz) in a controlled environment. A statistically significant difference in median fatigue life was found between as-cast and laser welded specimens (p welded specimens despite 70% penetration of the weld.

  17. From nanotechnology to nanogenotoxicology: genotoxic effect of cobalt-chromium nanoparticles

    Directory of Open Access Journals (Sweden)

    Zülal Atlı Şekeroğlu

    2013-03-01

    Full Text Available Nanotechnology is a multi-disciplinary technology that processes the materials that can be measured with nanometer-level and combines many research field or discipline. Nanomaterials (NMs are widely used in the fields of science, technology, communication, electronics, industry, pharmacy, medicine, environment, consumer products and military. Until recently little has been known about whether or not nanomaterials have the toxic or hazardous effects on human health and the environment. However, several studies have indicated that exposure to some nanomaterials, e.g. nanoparticles, can cause some adverse effects in humans and animals. Over the last years the number of publications focusing on nanotoxicology has gained momentum, but, there is still a gap about the genotoxicity of nanomaterials.Metal nanoparticles and their alloys with excellent mechanical properties are the materials which can be easily adapted to the mechanical conditions of the musculoskeletal system. Cobalt-chromium alloys are widely used in orthopedic applications as joint prosthesis and bone regeneration material, fillings and dental implants in jaw surgery, and in cardiovascular surgery, especially stent applications. Studies about cytotoxicity and genotoxicity of metal nanoparticles on human indicate that some metal nanoparticles have cytotoxic and genotoxic effects and they may be hazardous for humans. However, a few studies have been reported concerning the genotoxic effects of cobalt-chromium nanoparticles. The data from these studies indicate that cobalt-chromium nanoparticles have cytotoxic and genotoxic effects. It has been stated that the wear debris from implants cause DNA and chromosome damage in patients with cobalt-chromium replacements. It was also found that the risk of urinary cancers such as bladder, ureter, kidney and prostate in patients after hip replacement than among the wider population.Because there are very little biocompatibility and toxicity tests on

  18. Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties

    DEFF Research Database (Denmark)

    Jantzen, Christopher; Jørgensen, Henrik L; Duus, Benn R

    2013-01-01

    Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties.......Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties....

  19. Survey of cosmetics for arsenic, cadmium, chromium, cobalt, lead, mercury, and nickel content.

    Science.gov (United States)

    Hepp, Nancy M; Mindak, William R; Gasper, John W; Thompson, Christopher B; Barrows, Julie N

    2014-01-01

    As part of efforts to assess amounts of inorganic element contamination in cosmetics, the U.S. Food and Drug Administration contracted a private laboratory to determine the total content of seven potentially toxic or allergenic elements in 150 cosmetic products of 12 types (eye shadows, blushes, lipsticks, three types of lotions, mascaras, foundations, body powders, compact powders, shaving creams, and face paints). Samples were analyzed for arsenic, cadmium, chromium, cobalt, lead, and nickel by inductively coupled plasma-mass spectrometry and for mercury by cold vapor atomic fluorescence spectrometry. The methods used to determine the elements were tested for validity by using standard reference materials with matrices similar to the cosmetic types. The cosmetic products were found to contain median values of 0.21 mg/kg arsenic, 3.1 mg/kg chromium, 0.91 mg/kg cobalt, 0.85 mg/kg lead, and 2.7 mg/kg nickel. The median values for cadmium and mercury were below the limits of detection of the methods. The contract requirements, testing procedures, and findings from the survey are described.

  20. Measurement of nickel, cobalt and chromium in toy make-up by atomic absorption spectroscopy.

    Science.gov (United States)

    Corazza, Monica; Baldo, Federica; Pagnoni, Antonella; Miscioscia, Roberta; Virgili, Annarosa

    2009-01-01

    Cosmetics should not contain more than 5 ppm of nickel, chromium or cobalt and, in order to minimize the risk of sensitization in very sensitive subjects, the target amount should be as low as 1 ppm. However, there are no published reports on the presence of these metals in toy make-up. This study analysed 52 toy make-ups using atomic absorption spectroscopy. More than 5 ppm of nickel was present in 14/52 (26.9%) samples. Chromium exceeded 5 ppm in 28/52 (53.8%) samples, with values over 1000 ppm in 3 eye shadows. Cobalt was present in amounts over 5 ppm in 5/52 (9.6%) samples. Powdery toy make-up (eye shadows) had the highest levels of metals, and "creamy" toy make-up (lip gloss and lipsticks) the lowest. Toy make-ups are potentially sensitizing items, especially for atopic children, who have a damaged skin barrier that may favour penetration of allergens.

  1. Ultra-thin strut cobalt chromium bare metal stent usage in a complex real-world setting. (SOLSTICE Registry)

    NARCIS (Netherlands)

    Suttorp, M. J.; Stella, P. R.; Dens, J.; McKenzie, J. M.; Park, K. S.; Frambach, P.

    2015-01-01

    Aim To report clinical follow-up at 6 months after implantation of the ultra-thin strut cobalt chromiumSolarFlex stent in a real-world setting. Methods and results Patients (n=240) with single or multiple vessel coronary artery disease undergoing percutaneous coronary intervention (PCI) at four site

  2. Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints.

    Science.gov (United States)

    Zupancic, Rok; Legat, Andraz; Funduk, Nenad

    2006-10-01

    The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. The average tensile strength of brazed joints was 792 MPa and was significantly greater (P<.05) than the tensile strength of both types of

  3. Effect of recasting on the elastic modulus of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2007-01-01

    Full Text Available Background/Aim. Elastic modulus of metal-ceramic systems determines their flexural strength and prevents damages on ceramics during mastication. Recycling of basic alloys is often a clinical practice, despite the possible effects on the quality of the future metal-ceramic dentures. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the elastic modulus of metalceramic systems in making fixed partial dentures. Methods. The research was performed as an experimental study. Six metal-ceramic samples of nickel-chromium alloy (Wiron 99 and cobalt-chromium alloy (Wirobond C were made. Alloy residues were recycled through twelve casting generations with the addition of 50% of new alloy on the occasion of every recasting. Three- point bending test was used to determine elastic modulus, recommended by the standard ISO 9693:1999. Fracture load for damaging ceramic layer was recorded on the universal testing machine (Zwick, type 1464, with the speed of 0,05 mm/min. Results. The results of this research revealed significant differences between elasticity modules of metal-ceramic samples in every examined recycle generation. Recasting had negative effect on the elastic modulus of the examined alloys. This research showed the slight linear reduction of elastic modulus up to the 6th generation of recycling. After the 6th recycling there was a sudden fall of elastic modulus. Conclusion. Recasting of nickelchromium and cobalt-chromium alloys is not recommended because of the reduced elastic modulus of these alloys. Instead of reusing previously recasted alloys, the alloy residues should be returned to the manufacturer. .

  4. In Vivo Wear Performance of Cobalt-Chromium Versus Oxidized Zirconium Femoral Total Knee Replacements.

    Science.gov (United States)

    Gascoyne, Trevor C; Teeter, Matthew G; Guenther, Leah E; Burnell, Colin D; Bohm, Eric R; Naudie, Douglas R

    2016-01-01

    This study examines the damage and wear on the polyethylene (PE) inserts from 52 retrieved Genesis II total knee replacements to identify differences in tribological performance between matched pairs of cobalt-chromium (CoCr) and oxidized zirconium (OxZr) femoral components. Observer damage scoring and microcomputed tomography were used to quantify PE damage and wear, respectively. No significant differences were found between CoCr and OxZr groups in terms of PE insert damage, surface penetration, or wear. No severe damage such as cracking or delamination was noted on any of the 52 PE inserts. Observer damage scoring did not correlate with penetrative or volumetric PE wear. The more costly OxZr femoral component does not demonstrate clear tribological benefit over the standard CoCr component in the short term with this total knee replacement design.

  5. First-in-man evaluation of the MOMO cobalt-chromium carbon-coated stent.

    Science.gov (United States)

    Kesavan, Sujatha; Strange, Julian W; Johnson, Thomas W; Flohr-Roese, Silke; Baumbach, Andreas

    2013-01-22

    Bare metal stents continue to be used for the interventional treatment of coronary artery disease. We report the clinical and angiographic results of a multicentre, single-arm evaluation of safety and feasibility of the MOMO stent (Japan Stent Technology Co., Ltd, Okayama Research Park Incubation Centre, Okayama, Japan). The MOMO stent is a novel thin-strut cobalt-chromium carbon-coated stent for the treatment of de novo coronary artery disease (CAD). In this prospective, non-randomised, single-arm study, 40 patients (stable and unstable angina) with single-vessel CAD were recruited into the study from three centres. Patients with lesions ≤15 mm in length and with a target vessel diameter of ≥3 mm were eligible. Angiographic follow-up was performed at six months. Quantitative coronary angiography (QCA) was used to measure acute gain and late luminal loss (LLL). Intravascular ultrasound (IVUS) was performed in 15 consecutive patients from two centres to assess the degree of neointimal proliferation within the stented segment at six-month follow-up. The MOMO stent performed well without any procedural complications with an acute procedure and technical success rate of 100%. Repeat revascularisation was performed in six patients (15%) during the six-month follow-up. Ischaemia-driven revascularisation was documented in three patients (7.5%). No myocardial infarction, stent thrombosis or cardiac death was observed. One non-cardiac death was reported secondary to lung cancer. Binary restenosis was 12.5% (n=5), and the LLL was 0.54±0.3 mm. This first-in-man experience demonstrates proof of concept of the safety and feasibility of the MOMO cobalt-chromium carbon-coated stent for patients with single focal de novo lesions presenting with stable and unstable CAD.

  6. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

  7. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

  8. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

  9. Effect of laser irradiation conditions on the laser welding strength of cobalt-chromium and gold alloys.

    Science.gov (United States)

    Kikuchi, Hisaji; Kurotani, Tomoko; Kaketani, Masahiro; Hiraguchi, Hisako; Hirose, Hideharu; Yoneyama, Takayuki

    2011-09-01

    Using tensile tests, this study investigated differences in the welding strength of casts of cobalt-chromium and gold alloys resulting from changes in the voltage and pulse duration in order to clarify the optimum conditions of laser irradiation for achieving favorable welding strength. Laser irradiation was performed at voltages of 150 V and 170 V with pulse durations of 4, 8, and 12 ms. For cobalt-chromium and gold alloys, it was found that a good welding strength could be achieved using a voltage of 170 V, a pulse duration of 8 ms, and a spot diameter of 0.5 mm. However, when the power density was set higher than this, defects tended to occur, suggesting the need for care when establishing welding conditions.

  10. Effects of cobalt-chromium everolimus eluting stents or bare metal stent on fatal and non-fatal cardiovascular events

    DEFF Research Database (Denmark)

    Valgimigli, Marco; Sabaté, Manel; Kaiser, Christoph

    2014-01-01

    eluting stents with bare metal stents were selected. The principal investigators whose trials met the inclusion criteria provided data for individual patients. PRIMARY OUTCOMES: The primary outcome was cardiac mortality. Secondary endpoints were myocardial infarction, definite stent thrombosis, definite......OBJECTIVES: To examine the safety and effectiveness of cobalt-chromium everolimus eluting stents compared with bare metal stents. DESIGN: Individual patient data meta-analysis of randomised controlled trials. Cox proportional regression models stratified by trial, containing random effects, were...... or probable stent thrombosis, target vessel revascularisation, and all cause death. RESULTS: The search yielded five randomised controlled trials, comprising 4896 participants. Compared with patients receiving bare metal stents, participants receiving cobalt-chromium everolimus eluting stents had...

  11. Deposition of nickel, chromium, and cobalt on the skin in some occupations - assessment by acid wipe sampling.

    Science.gov (United States)

    Lidén, Carola; Skare, Lizbet; Nise, Gun; Vahter, Marie

    2008-06-01

    Nickel, chromium, and cobalt are important skin sensitizers. Better knowledge about skin exposure is needed for more efficient prevention. We have previously developed acid wipe sampling for assessment of skin exposure to metals. To apply the acid wipe sampling technique in some occupations where intense contact with metallic items occurs and to gather experience for the design of future workplace studies. 18 volunteers (carpenters, locksmiths, cashiers, and secretaries as controls) participated. They performed their normal tasks during a job session for exposure. Samples were taken from fingers and palms by acid wipe sampling, and analysis of metals was performed by inductively coupled plasma mass spectrometer. The metals were detected in all samples, and the amount of nickel was larger than that of chromium and cobalt. Fingers were more exposed than palms. 8-h exposure to nickel was calculated and was highest in locksmiths (mean 3.784 mug/cm(2), range 1.846-5.028 mug/cm(2)) followed by carpenters, cashiers, and secretaries. The acid wipe sampling technique is suitable for studies of skin exposure to nickel, chromium, and cobalt in the workplace. The sampling efficiency of acid wipe sampling is high. The amounts of nickel deposited on skin in carpenters, locksmiths, and cashiers are judged capable of eliciting allergic contact dermatitis.

  12. Surface modification of cobalt-chromium-tungsten-nickel alloy using octadecyltrichlorosilanes

    Energy Technology Data Exchange (ETDEWEB)

    Mani, Gopinath [Department of Biomedical Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Feldman, Marc D. [Department of Biomedical Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Division of Cardiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229 (United States); The Department of Veteran Affairs South Texas Health Care System, 7400 Merton Minter Blvd., San Antonio, TX 78229 (United States); Oh, Sunho [Department of Biomedical Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Agrawal, C. Mauli [Department of Biomedical Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States)], E-mail: Mauli.Agrawal@utsa.edu

    2009-03-15

    Cobalt-chromium (Co-Cr) alloys have been extensively used for medical implants because of their excellent mechanical properties, corrosion resistance, and biocompatibility. This first time study reports the formation and stability of self-assembled monolayers (SAMs) on a Co-Cr-W-Ni alloy. SAMs of octadecyltrichlorosilanes (OTS) were coated on sputtered Co-Cr-W-Ni alloy thin film and bulk Co-Cr-W-Ni alloy. OTS SAM coated alloy specimens were characterized using contact angle goniometry, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Contact angle analysis and FTIR suggested that ordered monolayers were coated on both sputtered and bulk alloy. XPS suggested the selective dissolution of cobalt from the alloy during the formation of OTS SAM. The bonding between the alloy and the OTS SAM was mainly attributed to Si-O-Cr and Si-O-W covalent bonds and a smaller contribution from Si-O-Co bonds. AFM images showed the distribution of islands of monolayers coated on the alloy. The height of monolayers in majority of the islands was closer to the theoretical length of fully extended OTS molecules oriented perpendicular to the surface. The stability of OTS SAM was investigated in tris-buffered saline at 37 {sup o}C for up to 7 days. Contact angle, FTIR, and XPS collectively confirmed that the monolayers remain ordered and bound to the alloy surface under this condition. This study shows that Co-Cr alloys can be surface modified using SAMs for potential biomedical applications.

  13. Macrophage responses to 316L stainless steel and cobalt chromium alloys with different surface topographies.

    Science.gov (United States)

    Anderson, Jordan A; Lamichhane, Sujan; Mani, Gopinath

    2016-11-01

    The surface topography of a biomaterial plays a vital role in determining macrophage interactions and influencing immune response. In this study, we investigated the effect of smooth and microrough topographies of commonly used metallic biomaterials such as 316 L stainless steel (SS) and cobalt-chromium (CoCr) alloys on macrophage interactions. The macrophage adhesion was greater on CoCr compared to SS, irrespective of their topographies. The macrophage activation and the secretion of most pro-inflammatory cytokines (TNF-α, IL-6, and IP-10) were greater on microrough surfaces than on smooth surfaces by day-1. However, by day-2, the macrophage activation on smooth surfaces was also significantly increased up to the same level as observed on the microrough surfaces, with more amount of cytokines secreted. The secretion of anti-inflammatory cytokine (IL-10) was significantly increased from day-1 to day-2 on all the alloy surfaces with the effect most prominently observed on microrough surfaces. The production of nitric oxide by the macrophages did not show any major substrate-dependent effect. The foreign body giant cells formed by macrophages were least observed on the microrough surfaces of CoCr. Thus, this study demonstrated that the nature of material (SS or CoCr) and their surface topographies (smooth or microrough) strongly influence the macrophage responses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2658-2672, 2016.

  14. Oligonucleotide biofunctionalization enhances endothelial progenitor cell adhesion on cobalt/chromium stents.

    Science.gov (United States)

    Barsotti, Maria Chiara; Al Kayal, Tamer; Tedeschi, Lorena; Dinucci, Dinuccio; Losi, Paola; Sbrana, Silverio; Briganti, Enrica; Giorgi, Rodorico; Chiellini, Federica; Di Stefano, Rossella; Soldani, Giorgio

    2015-10-01

    As the endothelium still represents the ideal surface for cardiovascular devices, different endothelialization strategies have been attempted for biocompatibility and nonthrombogenicity enhancement. Since endothelial progenitor cells (EPCs) could accelerate endothelialization, preventing thrombosis and restenosis, the aim of this study was to use oligonucleotides (ONs) to biofunctionalize stents for EPC binding. In order to optimize the functionalization procedure before its application to cobalt-chromium (Co/Cr) stents, discs of the same material were preliminarily used. Surface aminosilanization was assessed by infrared spectroscopy and scanning electron microscopy. A fluorescent endothelial-specific ON was immobilized on aminosilanized surfaces and its presence was visualized by confocal microscopy. Fluorescent ON binding to porcine blood EPCs was assessed by flow cytometry. Viability assay was performed on EPCs cultured on unmodified, nontargeting ON or specific ON-coated discs; fluorescent staining of nuclei and F-actin was then performed on EPCs cultured on unmodified or specific ON-coated discs and stents. Disc biofunctionalization significantly increased EPC viability as compared to both unmodified and nontargeting ON-coated surfaces; cell adhesion was also significantly increased. Stents were successfully functionalized with the specific ON, and EPC binding was confirmed by confocal microscopy. In conclusion, stent biofunctionalization for EPC binding was successfully achieved in vitro, suggesting its use to obtain in vivo endothelialization, exploiting the natural regenerative potential of the human body. © 2015 Wiley Periodicals, Inc.

  15. Critical evaluation on structural stiffness of porous cellular structure of cobalt chromium alloy

    Science.gov (United States)

    Abd Malek, N. M. S.; Mohamed, S. R.; Che Ghani, S. A.; Harun, W. S. Wan

    2015-12-01

    In order to improve the stiffness characteristics of orthopedic devices implants that mimic the mechanical behavior of bone need to be considered. With the capability of Additive layer manufacturing processes to produce orthopedic implants with tailored mechanical properties are needed. This paper discusses finite element (FE) analysis and mechanical characterization of porous medical grade cobalt chromium (CoCr) alloy in cubical structures with volume based porosity ranging between 60% to 80% produced using direct metal laser sintering (DMLS) process. ANSYS 14.0 FE modelling software was used to predict the effective elastic modulus of the samples and comparisons were made with the experimental data. The effective mechanical properties of porous samples that were determined by uniaxial compression testing show exponential decreasing trend with the increase in porosity. Finite element model shows good agreement with experimentally obtained stress-strain curve in the elastic regions. The models prove that numerical analysis of actual prosthesis implant can be computed particularly in load bearing condition

  16. Determination of labile copper, cobalt, and chromium in textile mill wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Crain, J.S.; Essling, A.M.; Kiely, J.T. [and others

    1997-01-01

    Copper, chromium, and cobalt species present in filtered wastewater effluent were separated by cation exchange and reverse phase chromatography. Three sample fractions were obtained: one containing metal cations (i.e., trivalent Cr, divalent Cu, and divalent Co), one containing organic species (including metallized dyes), and one containing other unretained species. The metal content of each fraction was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The sum of the corrected data was compared to the metal content of a filtered effluent aliquot digested totally with fuming sulfuric acid. Other aliquots of the filtered effluent were spiked with the metals of interest and digested to confirm chemical yield and accuracy. Method detection limits were consistently below 20 {mu}g L{sup -1} for Cu, 30 {mu}g L{sup -1} for Co, and 10 {mu}g L{sup -1} for Cr. Spike recoveries for undifferentiated Cu and Cr were statistically indistinguishable from unity; although Co spike recoveries were slightly low ({approximately}95%), its chemical yield was 98%. Copper retention on the sodium sulfonate cation exchange resin was closely correlated with the [EDTA]/[Cu] ratio, suggesting that metals retained upon the cation exchange column were assignable to labile metal species; however, mass balances for all three elements, though reasonable ({approximately}90%), were significantly different from unity. Mechanical factors may have contributed to the material loss, but other data suggest that some metal species reacted irreversibly with the reverse phase column. 3 refs., 2 figs., 4 tabs.

  17. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

    OpenAIRE

    2015-01-01

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wa...

  18. Cobalt, chromium and nickel contents in soils and plants from a serpentinite quarry

    Science.gov (United States)

    Lago-Vila, M.; Arenas-Lago, D.; Rodríguez-Seijo, A.; Couce, M. L. Andrade; Vega, F. A.

    2015-03-01

    The former serpentinite quarry of Penas Albas (Moeche, Galicia, NW Spain) left behind a large amount of waste material scattered over the surrounding area, as well as tailing areas. In this area several soils were studied together with the vegetation growing spontaneously over them with the aim of identifying the bioavailability of heavy metals. The potential of spontaneous vegetation for phytoremediation and/or phytostabilization was evaluated. The pH of the soils ranges from neutral to basic, with very low organic matter and nitrogen contents. There are imbalances between exchangeable cations like potassium (K) and calcium (Ca), mainly due to high magnesium (Mg) content that can strongly limit plant production. Moreover, in all of the studied soils there are high levels of cobalt (Co), chromium (Cr) and nickel (Ni) (>70, >1300 and >1300 mg kg-1, respectively). They exceed the intervention limits indicated by soil guideline values. Different soil extractions were performed in order to evaluate bioavailability. CaCl2 0.01 M is the most effective extraction reagent, although the reagent that best predicts plant availability is a mixture of low molecular weight organic acids. Festuca rubra, L. is the spontaneous plant growing in the soils that accumulates the highest amount of the metals, both in shoot and roots. Festuca also has the highest translocation factor values, although they are only >1 for Cr. The bioconcentration factor is >1 in all of the cases, except in the shoot of Juncus sp. for Co and Ni. The results indicate that Festuca is a phytostabilizer of Co and Ni and an accumulator of Cr, while Juncus sp. is suitable for phytostabilization.

  19. Wear behaviour of cobalt-chromium-molybdenum alloys used in metal-on-metal hip implants

    Science.gov (United States)

    Varano, Rocco

    The influence of carbon (C) content, microstructure, crystallography and mechanical properties on the wear behaviour of metal-on-metal (MM) hip implants made from commercially available cobalt-chromium-molybdenum (CoCrMo) alloys designated as American Society of Testing and Materials (ASTM) grade F1537, F75 and as-cast were studied in this work. The as-received bars of wrought CoCrMo alloys (ASTM F1537 of either about 0.05% or 0.26% C) were each subjected to various heat treatments to develop different microstructures. Pin and plate specimens were fabricated from each bar and were tested against each other using a linear reciprocating pin-on-plate apparatus in 25% by volume bovine serum solution. The applied normal load was 9.81 N and the reciprocating plate had a sinusoidal velocity with an average speed of 26 mm/s. The wear was measured gravimetrically and it was found to be most strongly affected by alloy C content, irrespective of grain size or carbide morphology. More precisely, the wear behaviour was directly correlated to the dissolved C content of the alloys. Increased C in solid-solution coincided with lower volumetric wear since C helps to stabilize the face-centred cubic (FCC) crystal structure thus limiting the amount of strain induced transformation (SIT) to the hexagonal close-packed crystal structure (HCP). Based on the observed surface twinning in and around the contact zone and the potentially detrimental effect of the HCP phase, it was postulated that the MM wear behaviour of CoCrMo alloys in the present study was controlled by a deformation mechanism, rather than corrosion or tribochemical reactions.

  20. Arsenic, cobalt and chromium food web biodilution in a Patagonia mountain lake.

    Science.gov (United States)

    Revenga, J E; Campbell, L M; Arribére, M A; Ribeiro Guevara, S

    2012-07-01

    Mussels, Diplon chilensis, from Lake Moreno, a double-basined mountain lake in southern Argentina, is known to have elevated concentrations of chromium (Cr, > 25 μg g⁻¹ dry weight DW) and arsenic (As, 35 μg g⁻¹ DW), attributed to untreated sewage. To further understand the trophodynamics of Cr, As and cobalt (Co), we investigated concentrations and transfer throughout the food web in each basin of Lake Moreno. Each basin differs in morphology in that the gently-sloping Lake Moreno West has more littoral habitat than deeper Lake Moreno East with its higher proportion of pelagic habitat. Despite the morphological differences, both basins share similar water quality parameters and species assemblages. As a result, Lake Moreno provides an exceptional opportunity to compare trophodynamics of elements that enable us to hypothesize pelagic-littoral habitat coupling in response to lake morphology as the underlying factor influencing both Cr pathway and Co and As trophodynamic modeling. Using stable isotopes of nitrogen (δ¹⁵N) and carbon (δ¹³C) to characterize metals trophodynamics in each basin, biodilution of As, Cr and Co were indicated by negative regressions. This is confirmed by elevated As, Co and Cr concentrations in phytoplankton (11.3±5.7, 7.4±4.9, 44.5±40.7 μg g⁻¹ DW respectively), while zooplankton and biofilm had the next elevated concentrations. Those elevated concentrations are in contrast with lower concentrations in sport fish such as rainbow trout (0.5±0.5, 0.2±0.3, 1.8±1.2 μg g⁻¹ DW). Higher concentrations of Cr in fish were associated with higher proportion of benthic/littoral prey items in western basin, and were confirmed by significant correlation with δ¹³C values. Arsenic, Co and Cr concentrations in fish, while elevated, do not post health risks to human or wildlife consumers.

  1. Effect of cobalt substitution on structural and magnetic properties and chromium adsorption of manganese ferrite nano particles

    Science.gov (United States)

    Ahalya, K.; Suriyanarayanan, N.; Ranjithkumar, V.

    2014-12-01

    Manganese ferrite (MnFe2O4) and cobalt doped manganese ferrite (Mn1-xCoxFe2O4) with x=0, 0.2, 0.4, 0.6, and 0.8 are synthesized at pH 11 and an annealing temperature of 900 °C, through co-precipitation technique. The particle sizes are found to be in the range of 30-35 nm. The varying dopant concentrations influence the crystalline edges, surface morphology and magnetic properties of the samples. Particle size initially increases for the incorporation of cobalt up to x=0.6 and then decreases. As cobalt concentration increases, the saturation magnetization increases up to x=0.6 and then decreases. Stretching and bending of bonds at tetrahedral and octahedral sites respectively are noticed and they shift towards the longer wavelengths. The samples are tested for their application as adsorbents of toxic heavy metal Cr(VI). The adsorption efficiency variations with dopant concentrations of samples, quantity of adsorbent and concentrations of chromium are studied.

  2. Cobalt.

    Science.gov (United States)

    Fowler, Joseph F

    2016-01-01

    Cobalt has been a recognized allergen capable of causing contact dermatitis for decades. Why, therefore, has it been named 2016 "Allergen of the Year"? Simply put, new information has come to light in the last few years regarding potential sources of exposure to this metallic substance. In addition to reviewing some background on our previous understanding of cobalt exposures, this article will highlight the recently recognized need to consider leather as a major site of cobalt and the visual cues suggesting the presence of cobalt in jewelry. In addition, a chemical spot test for cobalt now allows us to better identify its presence in suspect materials.

  3. HEAVY METALS ABUNDANCE IN THE SOILS OF THE PANTELIMON – BRĂNEŞTI AREA, ILFOV COUNTY a CADMIUM, COBALT, CHROMIUM, COPPER

    Directory of Open Access Journals (Sweden)

    Radu Lacatusu

    2011-12-01

    Full Text Available More than 20 years later, a new research on heavy metals (cadmium, cobalt, chromium, copper contents in the soil cover of the Pantelimon – Brăneşti area located East of the Bucharest Municipality and exposed for several decades to the influence of industrial emissions from two non-ferrous metallurgy plants is presented. A 5,912.72 ha area was investigated, 544 samples taken by geometric horizons (0-20; 20-40; 40-60 cm from 215 points have been analyzed.The dominant soils are: Preluvosols, Chernozems, Phaeozems. The analytical data showed that all the heavy metals contents are below the maximum allowable limits and of the alarm thresholds. Higher cadmium and copper concentrations have been registered in the 40-60 cm layer and higher chromium and copper concentrations in the 0-20 cm layer. Cadmium and cobalt distributions are non-central, with a right asymmetry, and the chromium and copper ones are slightly symmetric. The surface distribution of the heavy metals shows the presence of some high contents areas distributed insularly, with a higher frequency around the industrial units. The geochemical abundance indexes are higher than 1 for cadmium and lower for cobalt, chromium, and copper, and the pedo-geochemical abundance indexes are lower than 1 only for chromium.

  4. Time-dependent release of cobalt and chromium ions into the serum following implantation of the metal-on-metal Maverick type artificial lumbar disc (Medtronic Sofamor Danek).

    Science.gov (United States)

    Zeh, Alexander; Becker, Claudia; Planert, Michael; Lattke, Peter; Wohlrab, David

    2009-06-01

    In total hip endoprosthetics and consequently for TDA, metal-on-metal combinations are used with the aim of reducing wear debris. In metal-on-metal TDA the release of metal ions has until now been secondary to the main discussion. In order to investigate the ion release following the implantation of the metal-on-metal Maverick type artificial lumbar disc we measured the serum cobalt and chromium concentration following implantation of 15 Maverick TDAs (monosegmental L5/S1, n = 5; bisegmental L4/5 and L5/S1, n = 5; average age 36.5 years). Five healthy subjects (no metal implants) acted as a control group. The two measurements of the metals were carried out using the absorption spectrometry after an average of 14.8 and 36.7 months. In summary, the concentrations of cobalt and chromium ions in the serum at both follow-ups amounted on average to 3.3 microg/l (SD 2.6) for cobalt and 2.2 microg/l (SD 1.5) for chromium. These figures are similar to the figures shown in the literature following the implantation of metal-on-metal THA. After a comparison to the control group, both the chromium and cobalt levels in the serum showed visible increases regarding the first and the second follow-up. As there is still a significant release of cobalt and chromium into the serum after an average follow-up of 36.7 months a persistent release of these ions must be taken into consideration. Despite the evaluation of the systemic and local effects of the release of Cr/Co from orthopaedic implants has not yet been concluded, one should take into consideration an explanation given to patients scheduled for the implantation of a metal-on-metal TDA about these results and the benefits/risks of alternative combinations of gliding contact surfaces.

  5. Effect of selective laser melting deposition cobalt chromium alloy porcelain crown restoration on related molecule contents in serum and gingival crevicular fluid

    Institute of Scientific and Technical Information of China (English)

    Yu-Hua Wei; Lei Yang

    2015-01-01

    Objective:To study the effect of selective laser melting deposition cobalt chromium alloy porcelain crown restoration on contents of inflammatory cytokines and adhesion molecules in serum and gingival tissue.Methods:80 cases of patients who received cobalt chromium alloy porcelain crown restoration in our hospital from May 2013 to August 2014 were enrolled and randomly divided into two groups. Observation group received selective laser melting deposition cobalt chromium alloy porcelain crown restoration and control group received casting cobalt chromium metal porcelain crown restoration. Then contents of inflammatory cytokines and adhesion molecules in serum and gingival crevicular fluid of both groups were detected.Results: (1) Inflammatory cytokines: compared with serum inflammatory cytokine contents of control group, serum NF-κB, IL-6, IL-8, IL-1β, TNF-α and NO contents of observation group trended to decrease; (2) Adhesion molecules in gingival crevicular fluid: compared with adhesion molecule contents in gingival crevicular fluid of control group, mRNA contents of CD11a, CD18, LFA-1, E-selectin and P-selectin in gingival crevicular fluid of observation group trended to decrease; (3) Adhesion molecules in serum: compared with adhesion molecule contents in serum of control group, sICAM-1 and sVCAM-1 contents in serum of observation group were lower.Conclusion: Selective laser melting deposition cobalt chromium alloy porcelain crown restoration is helpful to relieve inflammatory response of gingival tissue, with expression of decreased generation of inflammatory cytokines and adhesion molecules; it’s an ideal material for crown restoration.

  6. Chromium

    Science.gov (United States)

    ... Intern Med 1991;115:917-24. Abraham AS, Brooks BA, Eylath U. The effects of chromium supplementation on serum glucose and lipids in patients with and without non-insulin-dependent diabetes. Metabolism 1992;41:768-71. Hermann J, Arquitt A. ...

  7. Cobalt-chromium-molybdenum alloy causes metal accumulation and metallothionein up-regulation in rat liver and kidney

    DEFF Research Database (Denmark)

    Jakobsen, Stig Storgaard; Danscher, Gorm; Stoltenberg, Meredin;

    2007-01-01

    Cobalt-chromium-molybdenum (CoCrMo) metal-on-metal hip prosthesis has had a revival due to their excellent wear properties. However, particulate wear debris and metal ions liberated from the CoCrMo alloys might cause carcinogenicity, hypersensitivity, local and general tissue toxicity, genotoxicity...... and inflammation-generating qualities. Nine months after implanting small pieces of CoCrMo alloy intramuscularly and intraperitoneally in rats, we analysed the accumulation of metals with a multi-element analysis, and the levels of metallothionein I/II with real-time reverse transcriptase-polymerase chain reaction...... in liver and kidney. We found that metal ions are liberated from CoCrMo alloys and suggest that they are released by dissolucytosis, a process where macrophages causes the metallic surface to release metal ions. Animals with intramuscular implants accumulated metal in liver and kidney and metallohionein I...

  8. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores.

    Science.gov (United States)

    El-Safty, Sherif A; Shenashen, Mohamed A; Sakai, Masaru; Elshehy, Emad; Halada, Kohmei

    2015-12-06

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

  9. Release of cobalt and chromium ions into the serum following implantation of the metal-on-metal Maverick-type artificial lumbar disc (Medtronic Sofamor Danek).

    Science.gov (United States)

    Zeh, Alexander; Planert, Michael; Siegert, Gabriele; Lattke, Peter; Held, Andreas; Hein, Werner

    2007-02-01

    Cross-sectional study of 10 patients to measure the serum levels of cobalt and chromium after TDA. To investigate the release of cobalt and chromium ions into the serum following implantation of the metal-on-metal Maverick-type artificial lumbar disc. In total hip endoprosthetics and consequently for TDA (total disc arthroplasty), metal-on-metal combinations are used with the aim of reducing wear debris. In metal-on-metal TDA the release of metal ions has until now been secondary to the main discussion. We investigated the serum cobalt and chromium concentration following implantation of 15 Maverick TDAs (monosegmental L5-S1, n = 5; bisegmental L4-L5 and L5-S1, n = 5; average age, 36.5 years). Five healthy subjects (no metal implants) acted as a control group. The measurements of the metals were carried out using the HITACHI Z-8200 AAS polarized Zeeman atomic absorption spectrometer after an average of 14.8 months. The concentrations of cobalt and chromium ions in the serum amounted on average to 4.75 microg/L (SD, 2.71) for cobalt and 1.10 microg/L (SD, 1.24) for chromium. Compared with control group, both the chromium and cobalt levels in the serum showed significant increases (Mann-Whitney U test, P = 0.0120). At follow-up,the Oswestry Disability Score was on average significantly decreased by 24.4 points (L5-S1) (t test, P < 0.05) and by 26.8 points (L4-S1) (t test, P < 0.05). The improved clinical situation is also represented by a significant decrease of the Visual Analog Pain Scale of 42.2 points after the follow-up (t test, P < 0.05). Significant systemic release of Cr/Co was proven in the serum compared with the control group. The concentrations of Cr/Co measured in the serum are similar in terms of their level to the values measured in THA metal-on-metal combinations or exceed these values given in the literature. Long-term implication of this metal exposure is unknown and should be studied further.

  10. Assessment of chromium, nickel, cobalt and zinc in edible flesh of ...

    African Journals Online (AJOL)

    ADOWIE PERE

    result, the safety of specific fish species for human consumption is constantly in doubt and needs assessment. ... melanotheron) are two of the highly consumed fish species in Bodo River. The level of .... model Turbo Quant (Lucas tooth) for calibration. 3. .... Cobalt has effect on reproduction and animal development.

  11. Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

    Science.gov (United States)

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-06-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks.

  12. Adverse reactions to metal on polyethylene implants: Highly destructive lesions related to elevated concentration of cobalt and chromium in synovial fluid.

    Science.gov (United States)

    Eltit, Felipe; Assiri, Ali; Garbuz, Donald; Duncan, Clive; Masri, Bassam; Greidanus, Nelson; Bell, Robert; Sharma, Manju; Cox, Michael; Wang, Rizhi

    2017-07-01

    Adverse local tissue reactions (ALTR) are the primary cause of failure of metal on metal (MoM) hip implants, and fewer but not negligible number cases of nonmodular metal on polyethylene (MoP) implants. In this study, we analyzed 17 cases of MoP ALTR, and equal number of MoM, by histological observation, cobalt and chromium concentration in serum and synovial fluid and cytokine analysis in ALTR tissues. ALTRs in MoP are highly necrotic, affecting larger areas than MoM ALTRs. Degenerative changes in blood vessels' wall were seen in all MoP ALTRs. The concentration of cobalt and chromium was higher in synovial fluid but lower in serum of MoP patients compared to MoM patients. Elevated concentrations of chemokines were observed in ALTR tissues. We conclude that ALTRs in MoP systems are highly necrotizing lesions that seem to have a similar development to ALTRs in MoM. Alteration of vessels wall seems to have a role in the tissues necrosis, as well as the elevated concentration of cobalt and chromium in synovial fluid of MoP patients. Chemokines may be involved in the pathogenesis of ALTR and constitute possible diagnostic targets. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1876-1886, 2017. © 2017 Wiley Periodicals, Inc.

  13. Rapid Prototyping for In Vitro Knee Rig Investigations of Prosthetized Knee Biomechanics: Comparison with Cobalt-Chromium Alloy Implant Material

    Directory of Open Access Journals (Sweden)

    Christian Schröder

    2015-01-01

    Full Text Available Retropatellar complications after total knee arthroplasty (TKA such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics.

  14. An investigation of force components in orthogonal cutting of medical grade cobalt-chromium alloy (ASTM F1537).

    Science.gov (United States)

    Baron, Szymon; Ahearne, Eamonn

    2017-02-01

    An ageing population, increased physical activity and obesity are identified as lifestyle changes that are contributing to the ongoing growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys, due to their mechanical properties and excellent biocompatibility, qualify as a class of materials that meet the stringent functional requirements of these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers rely on high-precision machining. However, a comprehensive literature review has shown that there has been limited research into the fundamental mechanisms in mechanical cutting of these alloys. This article reports on the determination of the basic cutting-force coefficients in orthogonal cutting of medical grade Co-Cr-Mo alloy ASTM F1537 over an extended range of cutting speeds ([Formula: see text]) and levels of undeformed chip thickness ([Formula: see text]). A detailed characterisation of the segmented chip morphology over this range is also reported, allowing for an estimation of the shear plane angle and, overall, providing a basis for macro-mechanic modelling of more complex cutting processes. The results are compared with a baseline medical grade titanium alloy, Ti-6Al-4V ASTM F136, and it is shown that the tangential and thrust-force components generated were, respectively, ≈35% and ≈84% higher, depending primarily on undeformed chip thickness but with some influence of the cutting speed.

  15. Evaluation of roughness and micromorphology of epoxy paint on cobalt-chromium alloy before and after thermal cycling.

    Science.gov (United States)

    Nascimento, Alessandra Cardoso da Silva; Muzilli, Carlos Alberto; Miranda, Milton Edson; Flório, Flávia Martão; Basting, Roberta Tarkany

    2013-01-01

    It has been suggested that the epoxy paint used to coat metal substrates in industrial electrostatic painting applications could also be used to mask metal clasps in removable dental prostheses (RDP). The purpose of this study was to evaluate both the influence of thermal cycling and the in vitro roughness of a surface after application of epoxy paint, as well as to assess the micromorphology of a cobalt-chromium (CoCr) based metal structure. Sixty test specimens were fabricated from a CoCr alloy. The specimens were separated into three groups (n = 20) according to surface treatment: Group 1 (Pol) - polished with abrasive stone and rubbers; Group 2 (Pol+Epo) - polished and coated with epoxy paint; Group 3 (Epo) - air-abraded with aluminum oxide particles and coated with epoxy paint. The surface roughness was evaluated before and after 1000 thermal cycles (5°C and 50°C). The surface micromorphology was verified by scanning electron microscopy (SEM). The two-way repeated measures ANOVA showed significant differences among surface treatments (p < 0.0001), but no difference was found before and after thermal cycling (p = 0.6638). The CoCr-based metal alloy surfaces treated with epoxy paint (Groups 2 and 3) were rougher than the surfaces that were only polished (Group 1). Thermal cycling did not influence surface roughness, or lead to chipping or detachment of the epoxy paint.

  16. Comparative study between laser sintering and casting for retention of resin composite veneers to cobalt-chromium alloy.

    Science.gov (United States)

    Muratomi, Ryuta; Kamada, Kohji; Taira, Yohsuke; Higuchi, Shizuo; Watanabe, Ikuya; Sawase, Takashi

    2013-01-01

    The purpose of this study was to evaluate and compare the bond strengths between resin composite veneer and laser-sintered cobalt-chromium (Co-Cr) alloy with and without retention devices (Laser-R and Laser-N respectively). Cast Co-Cr alloy with and without retention devices (Cast-R and Cast-N respectively) were also prepared for fabrication technique comparison. Disk-shaped Co-Cr alloy specimens were air-abraded with alumina and veneered with a veneering system, Estenia C&B (ES) or Ceramage (CE). After 20,000 thermocycles, tensile testing was performed. Data were analyzed by ANOVA and multiple comparison test. When no retention devices were present, no significant differences were observed between Laser-N/ES and Cast-N/ES, or between Laser- N/CE and Cast-N/CE, but ES exhibited significantly higher bond strength than CE. With retention devices, Laser-R/ES, Cast- R/ES and Laser-R/CE showed no significant differences, and their retention strengths were significantly higher than that of Cast- R/CE. Compared to cast Co-Cr alloy, laser-sintered Co-Cr alloy with retention devices provided better retention durability for resin composite-veneered prostheses.

  17. Cobalt as chemical modifier to improve chromium sensitivity and minimize matrix effects in tungsten coil atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sidnei G. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil); Donati, George L., E-mail: georgedonati@yahoo.com.br [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Santos, Luana N. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil); Jones, Bradley T. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Nóbrega, Joaquim A. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil)

    2013-05-30

    Graphical abstract: -- Highlights: •Charge transfer reactions increase the population of Cr{sup +}. •Chromium ions and electrons recombine to form excited-state Cr atoms. •A 10-fold improvement in LOD is observed for Cr emission measurements. •The two-step ionization/excitation mechanism improves sensitivity and accuracy. •High concentrations of Co also minimize matrix effects. -- Abstract: Cobalt is used as chemical modifier to improve sensitivity and minimize matrix effects in Cr determinations by tungsten coil atomic emission spectrometry (WCAES). The atomizer is a tungsten filament extracted from microscope light bulbs. A solid-state power supply and a handheld CCD-based spectrometer are also used in the instrumental setup. In the presence of 1000 mg L{sup −1} Co, WCAES limit of detection for Cr (λ = 425.4 nm) is calculated as 0.070 mg L{sup −1}; a 10-fold improvement compared to determinations without Co modifier. The mechanism involved in such signal enhancement is similar to the one observed in ICP OES and ICP-MS determinations of As and Se in the presence of C. Cobalt increases the population of Cr{sup +} by charge transfer reactions. In a second step, Cr{sup +}/e{sup −} recombination takes place, which results in a larger population of excited-state Cr atoms. This alternative excitation route is energetically more efficient than heat transfer from atomizer and gas phase to analyte atoms. A linear dynamic range of 0.25–10 mg L{sup −1} and repeatability of 3.8% (RSD, n = 10) for a 2.0 mg L{sup −1} Cr solution are obtained with this strategy. The modifier high concentration also contributes to improving accuracy due to a matrix-matching effect. The method was applied to a certified reference material of Dogfish Muscle (DORM-2) and no statistically significant difference was observed between determined and certified Cr values at a 95% confidence level. Spike experiments with bottled water samples resulted in recoveries between 93% and

  18. An in vitro Comparative Evaluation of Micro Tensile Bond Strength of Two metal bonding Resin Cements bonded to Cobalt Chromium alloy

    Science.gov (United States)

    Musani, Smita; Musani, Iqbal; Dugal, Ramandeep; Habbu, Nitin; Madanshetty, Pallavi; Virani, Danish

    2013-01-01

    Background: The purpose of this study was to evaluate and compare the micro tensile bond strength of two metal bonding resin cements to sandblasted cobalt chromium alloy. Materials & Methods: Eight, Cobalt chromium alloy blocks of dimensions 10x5x5 mm were cast, finished and polished. One of the faces of each alloy block measuring 5x5mm was sandblasted with 50 μm grit alumina particles. The alloy blocks were then cleaned in an ultrasonic cleaner for 1 min and then air dried with an air stream. The Sandblasted surfaces of the two alloy blocks were bonded together with 2 different metal bonding resin systems (Panavia F Kuraray and DTK Kleber – Bredent). The samples were divided into 2 groups (n=4). Group 1- Two Co-Cr blocks were luted with Panavia cement. Group 2- Two Co-Cr blocks were luted with DTK Kleber-Bredent cement. The bonded samples were cut with a diamond saw to prepare Microtensile bars of approximately 1mm x 1mm x 6mm. Thirty bars from each group were randomly separated into 2 subgroups (n=15) and left for 3hrs (baseline) as per manufacturer's instructions while the other group was aged for 24hrs in 370C water, prior to loading to failure under tension at a cross head speed of 1mm/min. Failure modes were determined by means of stereomicroscopy (sm). Statistical analysis was performed through one way – ANOVA. Results: Significant variation in micro-tensile bond strength was observed between the two metal bonding resin systems. Conclusion: DTK showed higher mean bond strength values than Panavia F cement both at baseline and after aging. How to cite this article: Musani S, Musani I, Dugal R, Habbu N, Madanshetty P, Virani D. An in vitro Comparative Evaluation of Micro Tensile Bond Strength of Two metal bonding Resin Cements bonded to Cobalt Chromium alloy. J Int Oral Health 2013;5(5):73-8. PMID:24324308

  19. Effect of storage time and framework design on the accuracy of maxillary cobalt-chromium cast removable partial dentures

    Science.gov (United States)

    Viswambaran, M.; Sundaram, R. K.

    2015-01-01

    Statement of Problem: Inaccuracies in the fit of palatal major connectors may be related to distortion of the wax pattern due to prolonged storage time and faulty major connector design. Purpose: This in vitro study was carried out to find out the effect of storage time and major connector design on the accuracy of cobalt-chromium cast removable partial dentures (RPDs). Materials and Methods: A brass metal die with a Kennedy Class III, modification 1, the partially edentulous arch was used as a master die. Thirty-six refractory casts were fabricated from the master die. The refractory casts were divided into three groups (Group I: Anterior-posterior palatal bar, Group II: Palatal strap and Group III: Palatal plate) based on the design of maxillary major connector and subdivided into four groups (sub Group A: 01 h, sub Group B: 03 h, Sub Group C: 06 h, and sub Group D: 24 h) based on the storage time. For each group, 12 frameworks were fabricated. The influence of wax pattern storage time and the accuracy of the fit palatal major connector designs on the master die were compared. Casting defects (nodules/incompleteness) of the frameworks were also evaluated before finishing and polishing. Repeated measures analysis of variance was used to analyze the data. Results: The gap discrepancy was least in sub Group A (01 h) followed by sub Group B (03 h) and C (06 h) and most in sub Group D (24 h). Statistically significant differences (P wax patterns for RPD to be invested immediately on completion of the wax procedure. The selection of a major connector design is crucial for an accurate fit of RPD. PMID:26681850

  20. Comparison and evaluation of marginal and internal gaps in cobalt-chromium alloy copings fabricated using subtractive and additive manufacturing.

    Science.gov (United States)

    Kim, Dong-Yeon; Kim, Ji-Hwan; Kim, Hae-Young; Kim, Woong-Chul

    2017-06-26

    To evaluate the marginal and internal gaps of cobalt-chromium (Co-Cr) alloy copings fabricated using subtractive and additive manufacturing. A study model of an abutment tooth 46 was prepared by a 2-step silicone impression with dental stone. Fifteen stereolithography files for Co-Cr alloy copings were compiled using a model scanner and dental CAD software. Using the lost wax (LW), wax block (WB), soft metal block (SMB), microstereolithography (μ-SLA), and selected laser melting (SLM) techniques, 15 Co-Cr alloy copings were fabricated per group. The marginal and internal gaps of these Co-Cr alloy copings were measured using a digital microscope (160×), and the data obtained were analyzed using the non-parametric Kruskal-Wallis H-test and post-hoc Mann-Whitney U-test with Bonferroni correction. The mean values of the marginal, axial wall, and occlusal gaps were 91.8, 83.4, and 163μm in the LW group; 94.2, 77.5, and 122μm in the WB group; 60.0, 79.4, and 90.8μm in the SMB group; 154, 72.4, and 258μm in the μ-SLA group; and 239, 73.6, and 384μm in the SLM group, respectively. The differences in the marginal and occlusal gaps between the 5 groups were statistically significant (P<.05). The marginal gaps of the LW, WB, and SMB groups were within the clinically acceptable limit, but further improvements in the μ-SLA and SLM approaches may be required prior to clinical implementation. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  1. Role of hyaluronic acid and phospholipid in the lubrication of a cobalt-chromium head for total hip arthroplasty.

    Science.gov (United States)

    Park, Jong-Bong; Duong, Cong-Truyen; Chang, Ho-Geun; Sharma, Ashish R; Thompson, Mark S; Park, Sungchan; Kwak, Byung-Chan; Kim, Tae-Young; Lee, Sang-Soo; Park, Seonghun

    2014-09-01

    The tribological performance of total hip arthroplasty has an important influence on its success rate. This study examined the concentration-dependent role of hyaluronic acid (HA) and phospholipid (dipalmitoylphosphatidylcholine, DPPC) in the boundary lubricating ability of retrieved cobalt-chromium femoral heads. The microscale frictional coefficients (μ) were measured by atomic force microscopy using a rectangular silicon cantilever integrated with sharp silicon tips. In the case of HA lubricant, the frictional coefficients decreased significantly at concentrations of 2.0 (0.16 ± 0.03) and 3.5 mg/ml (0.11 ± 0.01) while increased at 5.0 mg/ml (0.15 ± 0.01), compared to that with phosphate buffer saline (0.25 ± 0.03). The concentration-dependent lubrication behavior of DPPC was most effective when DPPC was in the physiological concentration range, showing μ = 0.16 ± 0.01 in polypropylene glycol, and 0.05 ± 0.01, 0.02 ± 0.01, and 0.03 ± 0.01 at a DPPC concentration of 0.05, 0.2, and 3.0 mg/ml, respectively. Results obtained show significant differences between the DPPC concentration groups. Conclusively, the microscale frictional response of the retrieved CoCr femoral head has a significant dependence on the concentrations of HA and DPPC. Moreover, observed optimal concentration of HA and DPPC for effective lubrication is similar to that observed in normal human synovial fluid. Therefore, a retrieval of the synovia may be considered during total hip replacement surgeries in an effort for reduction of friction between head and liner of total hip replacement implants.

  2. Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

    Science.gov (United States)

    Yoshinari, Masao; Uzawa, Shinobu; Komiyama, Yataro

    2016-10-01

    The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  3. Effect of annealing procedure on the bonding of ceramic to cobalt-chromium alloys fabricated by rapid prototyping.

    Science.gov (United States)

    Tulga, Ayca

    2017-08-22

    An annealing procedure is a heat treatment process to improve the mechanical properties of cobalt-chromium (Co-Cr) alloys. However, information is lacking about the effect of the annealing process on the bonding ability of ceramic to Co-Cr alloys fabricated by rapid prototyping. The purpose of this in vitro study was to evaluate the effects of the fabrication techniques and the annealing procedure on the shear bond strength of ceramic to Co-Cr alloys fabricated by different techniques. Ninety-six cylindrical specimens (10-mm diameter, 10-mm height) made of Co-Cr alloy were prepared by casting (C), milling (M), direct process powder-bed (LaserCUSING) with and without annealing (CL+, CL), and direct metal laser sintering (DMLS) with annealing (EL+) and without annealing (EL). After the application of ceramic to the metal specimens, the metal-ceramic bond strength was assessed using a shear force test at a crosshead speed of 0.5 mm/min. Shear bond strength values were statistically analyzed by 1-way ANOVA and Tukey multiple comparison tests (α=.05). Although statistically significant differences were found among the 3 groups (M, 29.87 ±2.06; EL, 38.92 ±2.04; and CL+, 40.93 ±2.21; P=.002), no significant differences were found among the others (P>.05). The debonding surfaces of all specimens exhibited mixed failure mode. These results showed that the direct process powder-bed method is promising in terms of metal-ceramic bonding ability. The manufacturing technique of Co-Cr alloys and the annealing process influence metal-ceramic bonding. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Ammine-Stabilized Transition-Metal Borohydrides of Iron, Cobalt, and Chromium: Synthesis and Characterization.

    Science.gov (United States)

    Roedern, Elsa; Jensen, Torben R

    2015-11-02

    Iron and cobalt borohydrides stabilized by ammonia (NH3), [Fe(NH3)6](BH4)2 and [Co(NH3)6](BH4)2, were synthesized along with a solid solution, [Co(NH3)6](BH4)(2-x)Cl(x) (x ∼ 1), and a bimetallic compound, [Fe(NH3)6](Li2(BH4)4). The compounds were prepared by new low-temperature, solvent-based synthesis methods, using dimethyl sulfide or liquid NH3, which allow for the removal of inert metal halides. The crystal structures were determined from synchrotron radiation powder X-ray diffraction (SR-PXD) data. [M(NH3)6](BH4)2 (M = Fe, Co) and [Co(NH3)6](BH4)(2-x)Cl(x) crystallize in the cubic crystal system, where the transition metals are octahedrally coordinated by NH3. Polymeric chains of lithium coordinated by four bridging BH4(-) anions are found in [Fe(NH3)6](Li2(BH4)4). The new compounds have high hydrogen densities of ∼14 wt % H2 and ∼140 g H2/L and release a mixture of hydrogen and NH3 gas at low temperatures, T < 80 °C. The decomposition mechanisms of the prepared compounds along with the composites [Fe(NH3)6](BH4)2·nNH3BH3 (n = 2, 4, 6) were studied by thermal analysis and in situ SR-PXD.

  5. Rationale and design of the EXAMINATION trial: A randomised comparison between everolimus-eluting stents and cobalt-chromium bare-metal stents in ST-elevation myocardial infarction

    NARCIS (Netherlands)

    M. Sabate (Manel); A. Cequier; A. Iñiguez (Andrés); A. Serra; R. Hernandez-Antolin (Rosana); V. Mainar (Vicente); M. Valgimigli (Marco); M. Tespili (Maurizio); P. den Heijer (Pieter); A. Bethencourt (Armando); N. Vazquez (Nicolás); S. Brugaletta (Salvatore); B.A.M.W. Backx (Bianca); P.W.J.C. Serruys (Patrick)

    2011-01-01

    textabstractAims: To assess the performance of the everolimus-eluting stent (EES) versus cobalt chromium bare-metal stent (BMS) in the setting of primary percutaneous coronary intervention for treatment of patients presenting with ST-segment elevation myocardial infarction (STEMI). The implantation

  6. Comparison of Repairing Effect Between Cobalt Chromium Alloy Porcelain Teeth and Zirconium Dioxide Porcelain Teeth%钴铬合金烤瓷牙和二氧化锆烤瓷牙修复效果对比

    Institute of Scientific and Technical Information of China (English)

    肖银蓉

    2015-01-01

    Objective To compare repairing effect of cobalt chromium alloy porcelain teeth and zirconium dioxide porcelain teeth. Methods To retrospective analyze 96 cases (172 tooth)clinical data of porcelain teeth prosthesis in our department from January 2010 to December 2013, the patients of zirconium dioxide porcelain teeth were 38 cases (70 tooth),which was zirconium dioxide porcelain teeth group,the patients of cobalt chromium alloy porcelain teeth were 58 cases(102 tooth), which was cobalt chromium alloy porcelain teeth group,the clinical result of two groups were compared. Results The effective rate 34 cases (94.73%)of zirco-nium dioxide porcelain teeth and effective rate 53 cases (91.37%)of cobalt chromium alloy porcelain teeth were compared, which was no difference (χ2=0.87,P>0.05). But after treatment of two groups,incidence of complications of cobalt chromium alloy porce-lain teeth group were higher than those of zirconium dioxide porcelain teeth group(χ2=3.95,P0.05)。但是两组患者治疗后,钴铬合金组并发症发生率高于二氧化锆组,差异有统计学意义(χ2=3.95,P<0.05)。结论二氧化锆烤瓷牙的疗效优于钴铬合金烤瓷牙,若患者经济条件允许,应该优先考虑二氧化锆烤瓷牙。

  7. Table of interplanar spacings for crystal-structure determinations by X-ray diffraction with molybdenum, copper, cobalt, iron, and chromium radiations

    Science.gov (United States)

    Kittel, J Howard

    1945-01-01

    For a simple diffraction pattern, the time required to calculate interplanar distances from measurements of the pattern is not excessive. If more than a few lines are present, however, or if several patterns are to be studied, it is very advantageous to have available a table giving interplanar spacings directly in terms of the linear measurements made on the film of the lines appearing on the diffraction pattern. The preparation of the table given here was undertaken when the expansion of research activities involving X-ray diffraction techniques indicated that such a table would greatly decrease the time required to analyze diffraction patterns. The table was prepared for use with K alpha(sub 1) radiation from the following target materials: molybdenum, copper, cobalt, iron, and chromium.

  8. Influence of Chemical Composition on Rupture Properties at 1200 Degrees F. of Forged Chromium-Cobalt-Nickel-Iron Base Alloys in Solution-Treated and Aged Condition

    Science.gov (United States)

    Reynolds, E E; Freeman, J W; White, A E

    1951-01-01

    The influence of systematic variations of chemical composition on rupture properties at 1200 degrees F. was determined for 62 modifications of a basic alloy containing 20 percent chromium, 20 percent nickel, 20 percent cobalt, 3 percent molybdenum, 2 percent tungsten, 1 percent columbium, 0.15 percent carbon, 1.7 percent manganese, 0.5 percent silicon, 0.12 percent nitrogen and the balance iron. These modifications included individual variations of each of 10 elements present and simultaneous variations of molybdenum, tungsten, and columbium. Laboratory induction furnace heats were hot-forged to round bar stock, solution-treated at 2200 degrees F., and aged at 1400 degrees F. The melting and fabrication conditions were carefully controlled in order to minimize all variable effects on properties except chemical composition. Information is presented which indicates that melting and hot-working conditions play an important role in high-temperature properties of alloys of the type investigated.

  9. Sirolimus-eluting cobalt-chromium stents: two-year clinical results from first-in-man study on the Firebird 2TM stent

    Institute of Scientific and Technical Information of China (English)

    Xu Bo; LI Jian-ping; CHEN Ji-lin; HUO Yong; GAO Run-lin; SHEN Wei-feng; ZHANG Qi; YANG Yue-jin; QIAO Shu-bin; ZHANG Rui-yan; ZHANG Jian-sheng; HU Jian; QIN Xue-wen; HONG Tao

    2008-01-01

    Background Drug-eluting stents(DES)have been shown to significantly reduce clinical events and angiographic restenosis in the treatment of coronary artery disease(CAD).This study was conducted to assess the long-term efficacy and safety of the polymer-based sirolimus-eluting cobalt-chromium Firebird 2TM stents in the treatment of patients with CAD.Methods This first-in-man study using the Firebird 2TM stent is a prospective,historically-controlled multicenter clinical study,which enrolled 67 patients with CAD who were treated with the sirolimus-eluting cobalt-chromium stent(Firebird 2TM,Microport Shanghai,Firebird 2 group),compared to another 49 patients treated with a bare cobalt alloy stent(Driver,Medtronic,control group).Continued 2-year clinical follow-up was performed after getting the initial 6-month angiographic and 1-year clinical follow-up.The incidence of major adverse cardiac events(MACE)including cardiac death,reinfarction and target lesion revascularization(TLR)and stent thrombosis were compared between the two groups.Results All patients in the Firebird 2 group(100.0%)and 48 patients in the control group(98.O%)completed the 2-year clinical follow-up.At the 1-year follow-up the use of the Firebird 2 stent was highly effective,resulting in a significant 94% decrease of TLR (26.5%in the control group and 1.5%in the Firebird 2 group,P<0.0001).A significant difference in TLR was maintained at 2-year follow-up,Firebird 2 group 1.5%and the control group 31.3%(P<0.0001).Between 1-and 2-year post-stenting.no more TLR occurred in the Firebird 2 group compared with two cases in the control group (P>0.05).There was a 1.5%incidence of MACE at 1-and 2-year follow-up in the Firebird 2 group,compared with 26.5% and 33.3%in the control group,respectively(all P<0.0001).The cumulative 1-and 2-year MACE free survival rates were 98.5%in the Firebird 2 group vs 73.5%and 66.7% in the control group (log rank P<0.0001).No case of stent thrombosis occurred during 2

  10. Estimated monthly streamflows for selected locations on the Kabul and Logar Rivers, Aynak copper, cobalt, and chromium area of interest, Afghanistan, 1951-2010

    Science.gov (United States)

    Vining, Kevin C.; Vecchia, Aldo V.

    2014-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Defense Task Force for Business and Stability Operations, used the stochastic monthly water-balance model and existing climate data to estimate monthly streamflows for 1951–2010 for selected streamgaging stations located within the Aynak copper, cobalt, and chromium area of interest in Afghanistan. The model used physically based, nondeterministic methods to estimate the monthly volumetric water-balance components of a watershed. A comparison of estimated and recorded monthly streamflows for the streamgaging stations Kabul River at Maidan and Kabul River at Tangi-Saidan indicated that the stochastic water-balance model was able to provide satisfactory estimates of monthly streamflows for high-flow months and low-flow months even though withdrawals for irrigation likely occurred. A comparison of estimated and recorded monthly streamflows for the streamgaging stations Logar River at Shekhabad and Logar River at Sangi-Naweshta also indicated that the stochastic water-balance model was able to provide reasonable estimates of monthly streamflows for the high-flow months; however, for the upstream streamgaging station, the model overestimated monthly streamflows during periods when summer irrigation withdrawals likely occurred. Results from the stochastic water-balance model indicate that the model should be able to produce satisfactory estimates of monthly streamflows for locations along the Kabul and Logar Rivers. This information could be used by Afghanistan authorities to make decisions about surface-water resources for the Aynak copper, cobalt, and chromium area of interest.

  11. Retention Load of Telescopic Crowns with Different Taper Angles between Cobalt-Chromium and Polyetheretherketone Made with Three Different Manufacturing Processes Examined by Pull-Off Test.

    Science.gov (United States)

    Wagner, Christina; Stock, Veronika; Merk, Susanne; Schmidlin, Patrick R; Roos, Malgorzata; Eichberger, Marlis; Stawarczyk, Bogna

    2016-04-01

    To investigate the retention loads of differently fabricated secondary telescopic polyetheretherketone (PEEK) crowns on cobalt-chromium primary crowns with different tapers. Cobalt-chromium primary crowns with 0°, 1°, and 2° tapers were constructed, milled, and sintered. Corresponding secondary crowns were fabricated by milling, pressing from pellets, and pressing from granules. For these nine test groups, the pull-off tests of each crown combination were performed 20 times, and the retention loads were measured (Zwick 1445, 50 mm/min). Data were analyzed using linear regression, covariance analysis, mixed models, Kruskal-Wallis, and Mann-Whitney U-test, together with the Benferroni-Holm correction. The mixed models covariance analysis reinforced stable retention load values (p = 0.162) for each single test sequence. There was no interaction between the groups and the separation cycles (p = 0.179). Milled secondary crowns with 0° showed the lowest mean retention load values compared to all tested groups (p = 0.003) followed by those pressed form pellets with 1°. Regarding the different tapers, no effect of manufacturing method on the results was observed within 1° and 2° groups (p = 0.540; p = 0.052); however, among the 0° groups, the milled ones showed significantly the lowest retention load values (p = 0.002). Among the manufacturing methods, both pressed groups showed no impact of taper on the retention load values (p > 0.324 and p > 0.123, respectively), whereas among the milled secondary crowns, the 0° taper showed significantly lower retention load values than the 1° and 2° taper (p manufacturing of PEEK materials for telescopic crowns are warranted, especially for 0°. © 2016 by the American College of Prosthodontists.

  12. Influence of cobalt and chromium additions on the precipitation processes in a Cu-4Ti alloys; Influencia de la adicion de cobalto y cromo en el proceso de precipitacion en una aleacion de Cu-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, E.

    2010-07-01

    The influence of 0.5% atomic cobalt and 1% atomic chromium additions on the precipitation hardening of Cu-4Ti alloy was studied by differential scanning calorimetry (DSC) and microhardness measurements. The analysis of the calorimetric curves, for binary alloy, shows the presence of two overlapping exothermic reactions (stages 1 and 2) attributed to the formation of Cu{sub 4}Ti and Cu{sub 3}Ti particles in the copper matrix, respectively. DSC curves for Cu-4Ti-0.5Co alloy shows three exothermic effects (overlapping stages 3 and 4 and stage 5) associated to the formation of phases Ti{sub 2}Co, TiCo and Cu{sub 4}Ti, respectively. DSC curves for Cu-4Ti1Cr alloy shows three exothermic reactions (stages 6, 7 and 9) and one endothermic peak (stage 8). The exothermic reactions correspond to the formation of phases Cr{sub 2}Ti, Cu{sub 4}Ti and Cu{sub 3}Ti, respectively, and the endothermic reactions are attributed to the Cr{sub 2}Ti dissolution. The activation energies calculated using the modified Kissinger method were lower than the ones corresponding to diffusion of cobalt, chromium, and titanium in copper. Kinetic parameters were obtained by a convolution method based on the Johnson-Mehl-Avrami (JMA) formalism. Microhardness measurements confirmed the formation of the mentioned phases. Also, these measurements confirmed the effect of cobalt and chromium addition on the binary alloy hardness. (Author). 31 refs.

  13. Determination of arsenic, cadmium, cobalt, chromium, lead, molybdenum, nickel, and selenium in fertilizers by microwave digestion and inductively coupled plasma-optical emission spectrometry detection: collaborative study.

    Science.gov (United States)

    Kane, Peter F; Hall, William L

    2006-01-01

    There is increasing regulatory interest in the non-nutritive metals content of fertilizer materials, but at present there is no consensus analytical method for acid digestion and instrument detection of those elements in fertilizer matrixes. This lack of method standardization has resulted in unacceptable variability of results between fertilizer laboratories performing metals analysis. A method has been developed using microwave digestion with nitric acid at 200 degrees C, followed by inductively coupled plasma-optical emission spectrometry instrument detection, for the elements arsenic, cadmium, cobalt, chromium, molybdenum, nickel, lead, and selenium. The method has been collaboratively studied, and statistical results are here reported. Fourteen collaborators were sent 62 sample materials in a blind duplicate design. Materials represented a broad cross section of fertilizer types, including phosphate ore, manufactured phosphate products, N-P-K blends, organic fertilizers, and micro-nutrient materials. As much as possible within the limit of the number of samples, materials were selected from different regions of the United States and the world. Limit of detection (LOD) was determined using synthetic fertilizers consisting of reagent grade chemicals with near zero levels of the non-nutritive elements, analyzed blindly. Samples with high iron content caused the most variability between laboratories. Most samples reasonably above LOD gave HorRat values within the range 0.5 to 2.0, indicating acceptable method performance according to AOAC guidelines for analyses in the mg/kg range. The method is recommended for AOAC Official First Action status.

  14. Casting accuracy of a nickel and beryllium-free cobalt-chromium alloy for crown and bridge prostheses and resin-bonded bridges.

    Science.gov (United States)

    Hansson, O

    1985-01-01

    In the 1970's economic factors dictated the development of alternatives to gold alloys in dentistry in the USA and in Europe. A similar development has not occurred in Sweden because of different laws. Alloys that contain nickel and beryllium present a health hazard and are therefore of little interest to the Swedish market. A review of the literature shows that castings of base-metal alloys are less accurate than castings of conventional gold alloys and of low gold alloys. However, in long-span-bridges and in thin resin-bonded cast restorations, their physical and mechanical properties are superior to those of the gold alloys. In this study the casting accuracy of a nickel- and beryllium-free cobalt-chromium alloy, Neobond II Special, is investigated. Neobond II Special was found to be less accurate than Sjödings C-guld. The marginal discrepancies of the castings were small, however, when the castings were oversized. It also proved to be technique sensitive to conventional dental laboratory procedures. Thus, it seems difficult to get castings with an acceptable retention as well as small marginal discrepancies when using the base-metal alloy.

  15. Ultrafine cobalt nanoparticles supported on reduced graphene oxide: Efficient catalyst for fast reduction of hexavalent chromium at room temperature

    Science.gov (United States)

    Xu, Tingting; Xue, Jinjuan; Zhang, Xiaolei; He, Guangyu; Chen, Haiqun

    2017-04-01

    A novel composite ultrafine cobalt nanoparticles-reduced graphene oxide (Co-RGO) was firstly synthesized through a modified one-step solvothermal method with Co(OH)2 as the precursor. The prepared low-cost Co-RGO composite exhibited excellent catalytic activity for the reduction of highly toxic Cr(VI) to nontoxic Cr(III) at room temperature when formic acid (HCOOH) was employed as the reductant, and its catalytic performance was even comparable with that of noble metal-based catalysts in the same reduction reaction. Moreover, Co-RGO composite could be readily recovered under an external magnetic field and efficiently participated in recycled reaction for Cr(VI) reduction.

  16. The clinical effects of artificial teeth in nickel-chromium alloy containing titanium, cobalt chromium alloy, high-gold alloy porcelain%含钛镍铬合金、钴铬合金、高金合金烤瓷牙的临床应用比较

    Institute of Scientific and Technical Information of China (English)

    李鸿飞

    2011-01-01

    Objective To compare clinical effects of the artificial teeth in nickel-chromium alloy containing titanium, cobalt chromium alloy, high-gold alloy-porcelain restorations. Methods The patients treated with nickel-chromium alloy containing titanium (n = 189, 233units) , cobalt chromium alloy (n = 206,251 units) and porcelain high-gold alloy (n =97, 118units) were observed in 3 months, 1 year, 3 years, including the color of porcelain crowns, gingival inflammation, gingival margin discoloration, and the crack or fracture or collapse of porcelain situation. Results There was no significant difference( P > 0.05 ) in color, gingival margin inflammation (3 months) , the crack or fracture or collapse of porcelain between artificial teeth in nickel-chromium alloy containing titanium andte cobalt chromium alloy-porcelain crown; the rate of gingival margin color (1 year and 3 years) of nickel-chromium alloy containing titanium group was higher than that of cobalt-chromium alloy group, and it was significantly higher than that of the high-gold alloy porcelain group ( P 0.05) . Conclusions The technic of high-gold alloy porcelain teeth has obvious advantages in chemical stability, biocompatibility and color; the artificial teeth in nickel chrome grill porcelain has been gradually replaced by the teeth made of cobalt-chromium alloy in recent years; the long term effects of Ni-Cr alloy-porcelain crown needs further research.%目的 比较含钛镍铬合金、钴铬合金、高金合金烤瓷修复体的临床应用效果.方法 选择含钛镍铬合金、钴铬合金和高金合金烤瓷修复患者分别为189例(233单位冠)、206例(251单位冠)和97例(118单位冠)修复完成后分别于3个月、1年、3年复查,检查烤瓷冠的色泽、牙龈炎症、龈缘变色以及裂纹或折裂或崩瓷情况.结果 含钛镍铬合金、钴铬合金烤瓷冠在色泽、龈缘炎症(3个月时)、裂纹或折裂或崩瓷方面无显著性差异(P>0.05);龈缘变色(1年及3

  17. Effect of production method on surface roughness, marginal and internal fit, and retention of cobalt-chromium single crowns.

    Science.gov (United States)

    Lövgren, Nils; Roxner, Rikard; Klemendz, Susanne; Larsson, Christel

    2017-07-01

    New production methods have been developed for metal-ceramic restorations. Different production methods may show different surface roughness and fit, which may affect retention and long-term success. The purpose of this in vitro study was to examine 3 different production methods with regard to surface roughness, marginal and internal fit, and retention of cobalt-chromium alloy single-crown copings. A master abutment of a premolar mandibular tooth preparation with 4-mm height and a 0.6-mm deep 120-degree chamfer finish line with a 12-degree angle of convergence was replicated in die stone and scanned. Thirty-six cobalt-chromium alloy copings were produced using 3 different production techniques. Twelve copings were produced by laser-sintering, 12 by milling, and 12 by milled wax/lost wax. The surface microstructure of 2 copings in each group was analyzed using interferometry. The remaining 10 copings in each group were used to evaluate marginal and internal fit by using an impression material replica method, and retention was evaluated by using a uniaxial tensile force pull-off test. The copings from each test group were cemented with zinc phosphate cement onto resin abutments. Statistical analyses of differences in marginal and internal fit were performed using 1-way ANOVA and the Mann-Whitney U test. Differences in surface topography were analyzed with the Kruskal-Wallis and Mann-Whitney U tests for nonparametric data. Differences in retentive values were analyzed using the Mann-Whitney U test for nonparametric data (all α=.05). Differences in surface microstructure were seen. The laser-sintered copings showed increased surface roughness compared with milled and milled wax/lost wax copings. Differences in marginal and internal fit were noted. Laser-sintered showed significantly smaller spaces between coping and abutment than milled wax/lost wax copings (P=.003). At the margins, laser-sintered copings showed significantly smaller spaces than either the milled

  18. PEEK Primary Crowns with Cobalt-Chromium, Zirconia and Galvanic Secondary Crowns with Different Tapers—A Comparison of Retention Forces

    Directory of Open Access Journals (Sweden)

    Veronika Stock

    2016-03-01

    Full Text Available In prosthetic dentistry, double crown systems have proved their suitability as retainers for removable partial dentures. However, investigations in this context, regarding polyetheretherketone, are scarce. Therefore, the aim of this study was to test the retention force (RF between polyetheretherketone (PEEK primary and cobalt-chromium (CoCr, zirconia (ZrO2 and galvanic (GAL secondary crowns with three different tapers. Primary PEEK-crowns were milled with the tapers 0°, 1°, and 2° (n = 10/taper, respectively. Afterwards, 90 secondary crowns were fabricated: (i 30 CoCr-crowns milled from Ceramill Sintron (AmannGirrbach, Koblach, Austria (n = 10/taper, (ii 30 ZrO2-crowns milled from Ceramill ZI (AmannGirrbach, Koblach, Austria (n = 10/taper, and (iii 30 GAL-crowns made using electroforming (n = 10/taper. RF was measured in a pull-off test (20 pull-offs/specimen and data were analyzed using 2-/1-way Analysis of Variance (ANOVA followed by the Tukey-Honestly Significant Difference (HSD post hoc test and linear regression analyses (p < 0.05. The measured mean RF values ranged between 9.6 and 38.2 N. With regard to the 0°, 1°, and 2° tapered crowns, no statistically significant differences between CoCr and ZrO2 were observed (p > 0.141. At 0° taper, no differences in retention forces between GAL, CrCr, and ZrO2 crowns were found (p = 0.075. However, at 1° and 2° taper, lower RF for GAL-crowns were observed (p < 0.009, p < 0.001, respectively. According to this laboratory study, PEEK might be a suitable material for primary crowns, regardless of the taper and the material of secondary crown. Long-term results, however, are still necessary.

  19. A systematic comparison of the actual, potential, and theoretical health effects of cobalt and chromium exposures from industry and surgical implants.

    Science.gov (United States)

    Keegan, Gemma M; Learmonth, Ian D; Case, C Patrick

    2008-01-01

    Humans are exposed to cobalt (Co) and chromium (Cr) from industry and surgical devices, most notably orthopedic joint replacements. This review compares the potential health effects of exposure to Co and Cr contaminants from these two different sources, both in the locally exposed tissues and at sites distant to the primary exposure. Surgical implantation results largely in exposures to ions, corrosion products, and particles of Co and Cr. Industrial exposures are predominantly to metal compounds and particles. Although there are large literatures on industrial and surgical exposures to these metals, there has yet to be a systematic comparison of the two to test whether more general lessons might be learned about the human toxicology of Co and Cr. Both industrial and surgical exposures cause inflammatory and other immune reactions in the directly exposed tissues. In the lung there is a well-established risk of cancer following long-term exposures to hexavalent Cr; however, the development of sarcoma in the connective tissues adjacent to implants in response to metal particles is rare. Both types of exposure are associated with changes in the peripheral blood, including evidence of oxidative stress, and altered numbers of circulating immune cells. There is dissemination of Co and Cr to sites distant to the orthopedic implant, but less is known about systemic dissemination of these metals away from the lung. The effects of industrial exposures in the reproductive, renal, and cardiac systems have been investigated, but this has yet to be explored after surgical exposures. The form of the metal (and associated elements) in both instances is key to the toxicological effects arising in the body and further characterization of debris released from devices is certainly recommended, as is the impact of nanotoxicology on the health and safety of workers and patients. Biomonitoring schemes currently used in industry could be translated, if required, into suitable programs for

  20. Contact sensitivity to metals (chromium, cobalt and nickel in childhood Alergia de contato aos metais (cromo, cobalto e níquel na infância

    Directory of Open Access Journals (Sweden)

    Marilda Helena Toledo Brandão

    2012-04-01

    Full Text Available Metals, especially nickel, are the most common contact allergens in children. Recent data has shown increased incidence of allergy in industrialized countries. Sensitization can occur at any age, even in neonates. Costume jewelry, particularly earrings, is linked to increased sensitization to nickel. Sensitization to cobalt often occurs by the use of costume jewelry. The most common source of sensitization to chromium is leather. Due to the absence of a specific therapy, the main treatment is to identify and avoid the responsible allergens. This article presents an updated view on the epidemiological and clinical aspects of contact allergy to metals, focusing on prevention strategies and risk factors, and warns about possible and new sources of contact.Os metais, especialmente o níquel, são os sensibilizantes de contato mais comuns em crianças. Dados recentes revelam aumento na incidência da alergia deste em países industrializados. A sensibilização pode ocorrer em qualquer idade, mesmo em recém-nascidos. Bijuterias, especialmente brincos nas orelhas, são ligadas ao aumento da sensibilização ao níquel. A sensibilização ao cobalto geralmente ocorre pelo uso de bijuterias. A fonte mais comum de sensibilização ao cromo é o couro. Devido à ausência de terapia específica, o principal tratamento consiste em identificar e evitar os alérgenos responsáveis. Este artigo pretende apresentar uma visão atualizada sobre os aspectos epidemiológicos e clínicos da alergia de contato aos metais, focando estratégias de prevenção e fatores de risco, além de alertar sobre as possíveis e novas fontes de contato.

  1. Prospective multi-center registry to evaluate efficacy and safety of the newly developed diamond-like carbon-coated cobalt-chromium coronary stent system.

    Science.gov (United States)

    Ando, Kenji; Ishii, Katsuhisa; Tada, Eiji; Kataoka, Kazuaki; Hirohata, Atsushi; Goto, Kenji; Kobayashi, Katsuyuki; Tsutsui, Hiroshi; Nakahama, Makoto; Nakashima, Hitoshi; Uchikawa, Shinichiroh; Kanda, Junji; Yasuda, Satoshi; Yajima, Junji; Kitabayashi, Hiroshi; Sakurai, Shumpei; Nakanishi, Keita; Inoue, Naoto; Noike, Hirofumi; Hasebe, Terumitsu; Sato, Tetsuya; Yamasaki, Masao; Kimura, Takeshi

    2017-07-01

    The purpose of this multi-center, non-randomized, and open-label clinical trial was to determine the non-inferiority of diamond-like carbon (DLC)-coated cobalt-chromium coronary stent, the MOMO DLC coronary stent, relative to commercially available bare-metal stents (MULTI-LINK VISION(®)). Nineteen centers in Japan participated. The study cohort consisted of 99 patients from 19 Japanese centers with single or double native coronary vessel disease with de novo and restenosis lesions who met the study eligibility criteria. This cohort formed the safety analysis set. The efficacy analysis set consisted of 98 patients (one case was excluded for violating the eligibility criteria). The primary endpoint was target vessel failure (TVF) rate at 9 months after stent placement. Of the 98 efficacy analysis set patients, TVF occurred in 11 patients (11.2 %, 95 % confidence interval 5.7-19.2 %) at 9 months after the index stent implantation. The upper 95 % confidence interval for TVF of the study stent was lower than that previously reported for the commercially available MULTI-LINK VISION(®) (19.6 %), demonstrating non-inferiority of the study stent to MULTI-LINK VISION(®). All the TVF cases were related to target vascular revascularization. None of the cases developed in-stent thrombosis or myocardial infarction. The average in-stent late loss and binary restenosis rate at the 6-month follow-up angiography were 0.69 mm and 10.5 %, respectively, which are lower than the reported values for commercially available bare-metal stents. In conclusion, the current pivotal clinical study evaluating the new MOMO DLC-coated coronary stent suggested its low rates of TVF and angiographic binary restenosis, and small in-stent late loss, although the data were considered preliminary considering the small sample size and single arm study design.

  2. A Comparison of the Marginal and Internal Fit of Cobalt- Chromium Copings Fabricated by Two Different CAD/CAM Systems (CAD/ Milling, CAD/ Ceramill Sintron).

    Science.gov (United States)

    Vojdani, Mahroo; Torabi, Kianoosh; Atashkar, Berivan; Heidari, Hossein; Torabi Ardakani, Mahshid

    2016-12-01

    Marginal fitness is the most important criteria for evaluation of the clinical acceptability of a cast restoration. Marginal gap which is due to cement solubility and plaque retention is potentially detrimental to both tooth and periodontal tissues. This in vitro study aimed to evaluate the marginal and internal fit of cobalt- chromium (Co-Cr) copings fabricated by two different CAD/CAM systems: (CAD/ milling and CAD/ Ceramill Sintron). We prepared one machined standard stainless steel master model with following dimensions: 7 mm height, 5mm diameter, 90˚ shoulder marginal finish line with 1 mm width, 10˚ convergence angle and anti-rotational surface on the buccal aspect of the die. There were 10 copings produced from hard presintered Co-Cr blocks according to CAD/ Milling technique and ten copings from soft non- presintered Co-Cr blocks according to CAD/ Ceramill Sintron technique. Marginal and internal accuracies of copings were documented by the replica technique. Replicas were examined at ten reference points under a digital microscope (230X). The Student's t-test was used for statistical analysis. pCAD/milling group (hard copings) had a mean marginal discrepancy (MD) of 104 µm, axial discrepancy (AD) of 23 µm and occlusal discrepancy of 130 µm. For CAD/ Ceramill Sintron group, these values were 195 µm (MD), 46 µm (AD), and 232 µm (OD). Internal total discrepancy (ITD) for the CAD/milling group was 77 µm, whereas for the CAD/Ceramill Sintron group was 143 µm. Hard presintered Co-Cr copings had significantly higher marginal and internal accuracies compared to the soft non-presintered copings.

  3. Role of direct reactivity with metals in chemoprotection by N-acetylcysteine against chromium(VI), cadmium(II), and cobalt(II).

    Science.gov (United States)

    Luczak, Michal W; Zhitkovich, Anatoly

    2013-12-01

    The antioxidant N-acetylcysteine (NAC) is widely used for the assessment of the role of reactive oxygen species (ROS) in various biological processes and adverse drug reactions. NAC has been found to effectively inhibit the toxicity of carcinogenic metals, which was attributed to its potent ROS-suppressive properties. However, the absence of redox activity among some metals and findings from genetic models suggested a more diverse, smaller role of oxidative stress in metal toxicity. Here, we examined mechanisms of chemoprotection by NAC against Cd(II), Co(II), and Cr(VI) in human cells. We found that NAC displayed a broad-spectrum chemoprotective activity against all three metals, including suppression of cytotoxicity, apoptosis, p53 activation, and HSP72 and HIF-1α upregulation. Cytoprotection by NAC was independent of cellular glutathione. NAC strongly inhibited the uptake of all three metals in histologically different types of human cells, explaining its high chemoprotective potential. A loss of Cr(VI) accumulation by cells was caused by NAC-mediated extracellular reduction of chromate to membrane-impermeative Cr(III). Suppression of Co(II) uptake resulted from a rapid formation of Co(II)-NAC conjugates that were unable to enter cells. Our results demonstrate that NAC acts through more than one mechanism in preventing metal toxicity and its chemoprotective activity can be completely ROS-independent. Good clinical safety and effectiveness in Co(II) sequestration suggest that NAC could be useful in the prevention of tissue accumulation and toxic effects of Co ions released by cobalt-chromium hip prostheses.

  4. Osteocyte physiology and response to fluid shear stress are impaired following exposure to cobalt and chromium: Implications for bone health following joint replacement.

    Science.gov (United States)

    Shah, Karan M; Orton, Peter; Mani, Nick; Wilkinson, Jeremy Mark; Gartland, Alison

    2017-08-01

    The effects of metal ion exposure on osteocytes, the most abundant cell type in bone and responsible for coordinating bone remodeling, remain unclear. However, several studies have previously shown that exposure to cobalt (Co(2+) ) and chromium (Cr(3+) ), at concentrations equivalent to those found clinically, affect osteoblast and osteoclast survival and function. In this study, we tested the hypothesis that metal ions would similarly impair the normal physiology of osteocytes. The survival, dendritic morphology, and response to fluid shear stress of the mature osteocyte-like cell-line MLO-Y4 following exposure to clinically relevant concentrations and combinations of Co and Cr ions were measured in 2D-culture. Exposure of MLO-Y4 cells to metal ions reduced cell number, increased dendrites per cell and increased dendrite length. We found that combinations of metal ions had a greater effect than the individual ions alone, and that Co(2+) had a predominate effect on changes to cell numbers and dendrites. Combined metal ion exposure blunted the responses of the MLO-Y4 cells to fluid shear stress, including reducing the intracellular calcium responses and modulation of genes for the osteocyte markers Cx43 and Gp38, and the signaling molecules RANKL and Dkk-1. Finally, we demonstrated that in the late osteoblasts/early osteocytes cell line MLO-A5 that Co(2+) exposure had no effect on mineralization, but Cr(3+) treatment inhibited mineralization in a dose-dependent manner, without affecting cell viability. Taken together, these data indicate that metal exposure can directly affect osteocyte physiology, with potential implications for bone health including osseointegration of cementless components, and periprosthetic bone remodeling. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1716-1723, 2017. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley

  5. Comparison of in vivo acute stent recoil between the bioabsorbable everolimus-eluting coronary stent and the everolimus-eluting cobalt chromium coronary stent: insights from the ABSORB and SPIRIT trials

    DEFF Research Database (Denmark)

    Tanimoto, Shuzou; Serruys, Patrick W; Thuesen, Leif

    2007-01-01

    the antiproliferative drug, everolimus, and expected to be totally metabolized and absorbed in the human body. Because the BVS is made from polymer, it may have more acute recoil than metallic stents in vivo. METHODS: A total of 54 patients, who underwent elective stent implantation for single de novo native coronary...... artery lesions, were enrolled: 27 patients treated with the BVS and 27 patients treated with the everolimus-eluting cobalt chromium stent (EES). Acute absolute recoil, assessed by quantitative coronary angiography, was defined as the difference between mean diameter of the last inflated balloon...

  6. Adhesion of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys: shear bond strength and sensitivity to thermocycling.

    Science.gov (United States)

    Serra-Prat, Josep; Cano-Batalla, Jordi; Cabratosa-Termes, Josep; Figueras-Àlvarez, Oscar

    2014-09-01

    New technologies have led to the introduction of new materials, so an evaluation of the adhesion of ceramics to these materials is needed. The purpose of this study was to compare the shear bond strength of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys, and to investigate the adhesive bond and failure type after thermocycling, 90 metal cylinders (10 mm diameter and 10 mm height) were prepared from cast (30 specimens), milled (30 specimens), and laser-sintered (30 specimens) alloys. Ceramic cylinders (2.5 mm diameter and 4 mm length) were fused to the alloy cylinders. For each group, 15 specimens were thermocycled 5500 times at temperatures between 4°C and 60°C before testing. After testing, the specimen surfaces were visually examined to determine the failure mode. Differences in adhesion values according to manufacturing method, testing condition (thermocycling or no thermocycling), and interaction between the factors were evaluated with a 2-way ANOVA. The χ(2) test (95% confidence level) was performed to determine whether the failure mode was associated with the testing condition. Adhesion strengths for the nonthermocycled specimens were 42.79 ±14.14 MPa (cast), 37.56 ±9.18 MPa (milled), and 29.09 ±6.95 MPa (laser-sintered), and, for the thermocycled specimens, 16.52 ±8.96 MPa (cast), 22.21 ±13.25 MPa (milled), and 24.28 ±10.13 MPa (laser-sintered). Two-way ANOVA results indicated no statistically significant differences in adhesion among the manufacturing methods (P=.257), but statistically significant differences were observed according to both testing conditions (Padhesion values for all the materials were adequate for clinical applications. No significant adhesion differences were observed between cast, milled, and laser-sintered specimens, or among thermocycled and nonthermocycled laser-sintered specimens. However, significant adhesion differences were observed among the thermocycled and nonthermocycled cast and

  7. Binuclear cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a new Schiff-base as ligand: synthesis, structural characterization, and antibacterial activity.

    Science.gov (United States)

    Geeta, B; Shravankumar, K; Reddy, P Muralidhar; Ravikrishna, E; Sarangapani, M; Reddy, K Krishna; Ravinder, V

    2010-11-01

    A binucleating new Schiff-base ligand with a phenylene spacer, afforded by the condensation of glycyl-glycine and o-phthalaldehyde has been served as an octadentate N₄O₄ ligand in designing some binuclear complexes of cobalt(II), nickel(II), copper(II), and palladium(II). The binding manner of the ligand to the metal and the composition and geometry of the metal complexes were examined by elemental analysis, conductivity measurements, magnetic moments, IR, ¹H, ¹³C NMR, ESR and electronic spectroscopies, and TGA measurements. There are two different coordination/chelation environments present around two metal centers of each binuclear complex. The composition of the complexes in the coordination sphere was found to be [M₂(L)(H(2)O)₄] (where M=Co(II) and Ni(II)) and [M₂(L)] (where M=Cu(II) and Pd(II)). In the case of Cu(II) complexes, ESR spectra provided further information to confirm the binuclear structure and the presence of magnetic interactions. All the above metal complexes have shown moderate to good antibacterial activity against Gram-positive and Gram-negative bacteria.

  8. Dermatite de contato por metais: prevalência de sensibilização ao níquel, cobalto e cromo Metal contact dermatitis: prevalence of sensitization to nickel, cobalt and chromium

    Directory of Open Access Journals (Sweden)

    Ida Duarte

    2005-04-01

    Full Text Available FUNDAMENTOS: Dermatite de contato (DC por metais é dermatose comum em diversos grupos populacionais. OBJETIVOS: Caracterizar o grupo com DC ao níquel, cromo e cobalto na população estudada, determinar a prevalência da sensibilização aos mesmos, verificar as combinações de testes positivos e comparar com a literatura. CASUÍSTICAS E MÉTODOS: Foram realizados testes epicutâneos em 1.208 pacientes com hipótese diagnóstica de DC. Selecionaram-se aqueles com testes positivos aos metais. RESULTADOS: Obtiveram-se 404 pacientes (33,5% da amostra com pelo menos um teste positivo ao níquel e/ou cobalto e/ou cromo. Foram 487 testes positivos a metais, correspondendo a 48% de todos os testes positivos. A maioria dos pacientes era do sexo feminino (72%, de cor branca (54%, com idade entre 40 e 49 anos (25% empregada na área de limpeza (59%. Dos 404, 329 (81,5% foram positivos a apenas um tipo de metal, sendo 60% com teste positivo ao níquel, 13% ao cromo e 8,5% ao cobalto. Cerca de 18,5% apresentaram testes positivos a dois ou três metais, sendo a associação níquel/cobalto a mais comum. CONCLUSÕES: A sensibilização aos metais foi de 48%, entre os testes positivos e ocorreu principalmente em mulheres da cor branca, na faixa etária de 40 a 49 anos e sem correlação ocupacional. A maioria apresentou sensibilização a apenas um metal. Esses dados são semelhantes aos de outros trabalhos já publicados.BACKGROUND: Metal contact dermatitis (nickel, cobalt and chromium is a common dermatosis among several population groups. OBJECTIVE: To describe the individuals with metal contact dermatitis in the group studied, to determine the prevalence of skin sensitization by nickel, cobalt and chromium, to verify the positive test combinations among these three substances and to compare our results with the literature. PATIENTS AND METHODS: Patch test was performed in 1208 patients with a presumptive diagnosis of contact dermatitis. Those with

  9. Avaliação da fundibilidade de uma liga de cobalto-cromo Castability evaluation of a cobalt-chromium alloy

    Directory of Open Access Journals (Sweden)

    Adriana da Fonte Porto CARREIRO

    1999-04-01

    Full Text Available Neste trabalho propusemo-nos a avaliar a fundibilidade de uma liga de cobalto-cromo (VERA-PDI em função da utilização de três revestimentos: Knebel (aglutinado por sílica, Termocast e Wirovest (aglutinados por fosfato e duas temperaturas de aquecimento para o molde (900°C e 950°C. Para a execução do teste foi utilizado o método descrito por HINMAN et al.9 (1985. O método de fundição foi o de cera perdida sob chama de gás-oxigênio. Os dados obtidos foram submetidos a análise estatística e demonstraram não haver diferença estatisticamente significante para os revestimentos Knebel e Wirovest, e diferença estatisticamente significante ao nível de 0,1% para o revestimento Termocast quando da variação da temperatura de aquecimento do molde. Quando analisamos os revestimentos sob temperatura do molde de 900°C verificamos diferença estatisticamente significante entre Knebel e Termocast e Knebel e Wirovest ao nível de 0,1%, e diferença entre Termocast e Wirovest ao nível de 5%. Para a temperatura de 950°C houve diferença estatisticamente significante ao nível de 0,1% entre todos os revestimentos. Dentro dos parâmetros utilizados neste estudo pudemos concluir que, para a liga VERA-PDI, a utilização do revestimento Knebel e temperatura de aquecimento do molde de 950°C proporcionaram melhores resultados quanto à fundibilidade.The purpose of this study was to evaluate the castability of a cobalt-chromium alloy (Vera-PDI using three investments: Knebel (agglutinated by silica, Termocast and Wirovest (both agglutinated by phosphate at two molding temperatures (900°C and 950°C; using HINMAN et al.9 (1985; methodology. The casting method of using a wax and gas-oxygen flame was used. There was no significant statistical difference between the Knebel and Wirovest investments; however, there was a statistically significant difference for Termocast investment (P < 0.1 at the different temperatures. When analyzing the

  10. Prospective comparison study of one-year outcomes for all titanium total temporomandibular joint replacements in patients allergic to metal and cobalt-chromium replacement joints in patients not allergic to metal.

    Science.gov (United States)

    Hussain, O T; Sah, S; Sidebottom, A J

    2014-01-01

    We aimed to ascertain whether there are any early differences in outcome between all titanium temporomandibular joint (TMJ) prostheses in patients allergic to metal and standard cobalt-chromium prostheses in patients not allergic to metal. All patients who had primary TMJ prostheses placed with one-year follow-up between March 2003 and February 2011 were included. We reviewed the basic characteristics of patients. The outcome variables measured included disease, pain, mouth opening, and diet. A total of 55 patients with 77 joint replacements fulfilled the inclusion criteria. Forty patients had standard cobalt-chromium alloy (Co-Cr-Mo) prostheses (20 unilateral and 20 bilateral), and 15 had all titanium prostheses (13 unilateral and 2 bilateral). Osteoarthritis was the most common disease in both groups. There was significant improvement in pain score at reviews at 6 weeks (p=0.001) and 12 months (p=0.03). Values between groups were not significant (p=0.48 at 6 weeks, and p=0.10 at 1 year). Mouth opening in each group improved significantly with continued gains between assessments at 6 weeks and 12 months (p=0.001) but there were no significant differences between groups. Diet scores were significantly improved one year postoperatively in both groups (p=0.001), but differences between groups were not significant (p=0.90). At one year, outcomes for all titanium prostheses in patients allergic to metal were similarly favourable to those in patients who had no hypersensitivity to metal and had standard prostheses. No patient developed a hypersensitivity reaction, and no all titanium prosthesis failed during the one-year follow-up period. Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. In Vitro Analyses of the Toxicity, Immunological, and Gene Expression Effects of Cobalt-Chromium Alloy Wear Debris and Co Ions Derived from Metal-on-Metal Hip Implants

    Directory of Open Access Journals (Sweden)

    Olga M. Posada

    2015-07-01

    Full Text Available Joint replacement has proven to be an extremely successful and cost-effective means of relieving arthritic pain and improving quality of life for recipients. Wear debris-induced osteolysis is, however, a major limitation and causes orthopaedic implant aseptic loosening, and various cell types including macrophages, monocytes, osteoblasts, and osteoclasts, are involved. During the last few years, there has been increasing concern about metal-on-metal (MoM hip replacements regarding adverse reactions to metal debris associated with the MoM articulation. Even though MoM-bearing technology was initially aimed to extend the durability of hip replacements and to reduce the requirement for revision, they have been reported to release at least three times more cobalt and chromium ions than metal-on-polyethylene (MoP hip replacements. As a result, the toxicity of metal particles and ions produced by bearing surfaces, both locally in the periprosthetic space and systemically, became a concern. Several investigations have been carried out to understand the mechanisms responsible for the adverse response to metal wear debris. This   review aims at summarising in vitro analyses of the toxicity, immunological, and gene expression effects of cobalt ions and wear debris derived from MoM hip implants.

  12. 无钴硫酸体系三价铬黑色钝化工艺%Process for trivalent chromium black passivation in cobalt-free sulfuric acid system

    Institute of Scientific and Technical Information of China (English)

    柯昌美; 周黎琴; 汪振忠; 张金龙; 王茜; 张利玉; 陈红祥

    2012-01-01

    以过渡金属硫化物M替代钴(镍)盐作发黑剂,在镀锌层表面得到黑色钝化膜.钝化液的配方与工艺为:Cr2(SO4)335 g/L,有机羧酸X 6 g/L,柠檬酸32 g/L,过渡金属硫化物M2g/L,FeSO410 g/L,NaNO37 g/L,NaH2PO415 g/L,pH=2.0,室温,时间30 s.钝化膜层乌黑均匀、附着力合格;经封闭后的三价铬黑色钝化膜,其耐蚀性等级高于市售含钴盐发黑剂的三价铬黑色钝化膜,且达到六价铬钝化的耐蚀等级;钝化膜中不含六价铬;钝化液性能稳定.%A black passivation film was obtained on surface of zinc coating by using transition-metal sulfide (code: M) instead of cobalt or nickel salt as blackening agent. The bath composition and passivation process parameters are as follows: Cr2(SO4)3 35 g/L, organic carboxylic acid (code: X) 6 g/L, citric acid 32 g/L, transition-metal sulfide M 2 g/L, FeSO4 10 g/L, NaNO3 7 g/L, NaH2PO4 15 g/L, pH = 2.0, room temperature, and time 30 s. The obtained passivation film is black and uniform, and of qualified adhesion. The corrosion resistance of sealed black trivalent chromium passivation film is higher than that of passivation film prepared from commercial passivation solution containing cobalt salt, and is equal to that of hexavalent chromium passivation film. The black passivation film is free of hexavalent chromium. The passivation bath has stable performance.

  13. 反复熔铸影响新旧钴铬烤瓷合金的机械性能%Mechanical properties of cobalt-chromium alloys containing different proportion of once-used alloys after recasts

    Institute of Scientific and Technical Information of China (English)

    肖月; 任丹丹; 王丹

    2013-01-01

    背景:目前关于反复铸造后钴铬烤瓷合金机械性能改变的研究已有较多研究报道,而对于将回收旧料再利用于新料中后再铸造钴铬烤瓷合金机械性能的研究则少有报道。  目的:研究反复熔铸对不同比例新旧钴铬烤瓷合金拉伸强度、屈服强度、延伸率及显微硬度等机械性能的影响。  方法:由新钴铬烤瓷合金熔铸成Ⅰ代铸件,40%Ⅰ代废旧料添加60%新钴铬烤瓷合金熔铸成Ⅱ代铸件,40%Ⅱ代废旧料添加60%新钴铬烤瓷合金熔铸成Ⅲ代铸件,40%Ⅲ代废旧料添加60%新钴铬烤瓷合金熔铸成第Ⅳ代铸件。采用拉伸实验测试各代试件的拉伸强度、0.2%屈服强度、延伸率;采用弯曲实验测试各代试件的弯曲强度;采用硬度实验测试各代试件的维氏硬度值;并进行显微金相观察。  结果与结论:Ⅱ,Ⅲ,Ⅳ代铸件拉伸强度、0.2%屈服强度、延伸率、弯曲强度及维氏硬度值与Ⅰ代铸件比较,差异均无显著性意义。Ⅰ代试样晶粒的大小均匀一致,直径较小,沿晶界分布的碳化物大小也较均匀细小,主要呈球形和不规则的蠕虫状两种形态;Ⅱ代和Ⅲ代试样组织形态尚均匀,只是晶粒有些粗化;Ⅳ代试样显微组织中的碳化物开始粗化,不规则蠕虫状的碳化物含量增多,可发现晶粒内存在少量非金属夹杂物。表明新旧比例为3∶2的钴铬烤瓷合金至少可以反复熔铸3次而不引起机械性能下降。%BACKGROUND:There are numerous studies about mechanical changes of recast cobalt-chromium ceramic al oys. However, little is reported on the mechanical properties of cobalt-chromium ceramic al oys containing once-used al oys after recasts. OBJECTIVE:To study the effects of different proportion of once-used al oys to recasting cobalt-chromium al oys on their mechanical properties, including tensile strength, yield strength, elongation and

  14. 氟离子对两种不同工艺制作的钴铬合金耐腐蚀性能的影响%Effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes

    Institute of Scientific and Technical Information of China (English)

    杨秋霞; 杨瑛; 徐晗; 吴迪; 郭恪

    2016-01-01

    目的:   在模拟口腔环境下研究氟离子对采用选择性激光熔覆(SLM)技术和传统铸造技术两种工艺制作的钴铬合金耐腐蚀性的影响。方法   选择具有相同材料成分的钴铬合金金属粉末和金属块,分别采用SLM(SLM组)和铸造技术(Cast组)各制作15个试件,置于含不同氟离子质量分数(0、0.05%、0.20%)的酸性人工唾液(pH值为5.0)中浸泡24 h进行电化学试验,采用动电位极化曲线法测试合金的自腐蚀电位Ecor、自腐蚀电流密度Icor和极化电阻Rp,同时结合扫描电子显微镜(SEM)观察,分析两组试件的耐腐蚀性能。结果   铸造工艺制作的钴铬合金在酸性人工唾液中的Ecor随着氟离子质量分数的升高而减小。当氟离子质量分数为0.20%时,两种工艺制作的钴铬合金的Ecor、Icor、Rp均有明显改变(P<0.05),SEM结果也显示合金表面均出现腐蚀现象。当氟离子质量分数为0.20%时,Cast组钴铬合金的Icor高于SLM组,而Ecor和Rp低于SLM组(P<0.05)。结论   氟离子可降低两种工艺制作的钴铬合金的耐腐蚀性,在氟离子质量分数较高(0.20%)时,SLM技术制作的钴铬合金的耐腐蚀性优于铸造工艺制作的钴铬合金。%Objective This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobaltchromium alloy fabricated by two different technology processes in a simulated oral environment. Methods A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH=5.0). The specimens were soaked in

  15. Investigation of structural, magnetic, electrical and optical properties of chromium substituted cobalt ferrites (CoCrxFe2-xO4, 0 ⩽ x ⩽ 1) synthesized using sol gel auto combustion method

    Science.gov (United States)

    Singhal, Sonal; Jauhar, Sheenu; Singh, Jagdish; Chandra, Kailash; Bansal, Sandeep

    2012-03-01

    The structural, magnetic, electrical and optical properties of chromium substituted cobalt ferrites (CoCrxFe2-xO4, x = 0.2, 0.4, 0.6, 0.8 and 1.0), have been investigated and on the basis of the saturation magnetization values, the cation distribution in the ferrite samples has been proposed. It is suggested that both Co2+ ions as well as Cr3+ ions seek to the octahedral sites of the ferrite sub-lattice. However, a small amount of Co2+ ions are also incorporated in the tetrahedral sites of the ferrite sub-lattice. This causes a decrease in the saturation magnetization (Ms) values with increasing Cr3+ concentration. The increase in Cr3+ ion composition in the ferrite sample decreases the value of saturation magnetization from 77 emu/g to 13 emu/g, indicative of the fact that the lesser magnetic Cr3+ ions substitute Fe3+ ions in the octahedral sub-lattice of the ferrites. A significant decrease in the saturation magnetization is observed in CoCrFeO4, attributing to the weakening of the A-B interaction as iron enters into the A site. The magnetic moments calculated from the proposed cation distribution (using Neel's two sub-lattice model) are in conformity with those obtained from Ms values. The effect of annealing temperature on structural, magnetic, electrical and optical properties has also been investigated.

  16. Determination on Iron, Copper, Chromium, Cadmium, Lead, Nickel and Cobalt in Hair Dye%染发剂中铁、铜、铬、镉、铅、镍和钴等重金属含量测定

    Institute of Scientific and Technical Information of China (English)

    解楠; 顾宇翔; 周泽琳

    2012-01-01

    建立了微波消解前处理,电感耦合等离子发射光谱(ICP-AES)测定染发剂中铁、铜、铬、镉、铅、镍和钴等重金属含量的方法.该方法各元素检出限均为0.05 mg/kg,线性范围0~500 ng/mL,加标回收率86.8%~108.0%,相对标准偏差为0.98%~5.54%.该方法简便、灵敏,结果稳定准确,可以用于染发剂中重金属含量的测定.%An inductively coupled plasma-atomic emission spectrometry (ICP-AES) with samples microwave digestion method for determination of Iron, Copper, Chromium, Cadmium, Lead, Nickel and Cobalt in hair dye was established. The detection limits of all elements were 0.05 mg/kg, the linearity ranged from 0 to 500 ng/mL, and recoveries of samples were in the range of 86. 8%~108. 0%, the RSD of precision is from 0. 98% to 5.54%. It indicates that the method is simple, sensitive, stable and accurate, which can be used for the determination of heavy metal elements in hair dye.

  17. Prospective, multi-center evaluation of a silicon carbide coated cobalt chromium bare metal stent for percutaneous coronary interventions: Two-year results of the ENERGY Registry

    Energy Technology Data Exchange (ETDEWEB)

    Erbel, Raimund, E-mail: erbel@uk-essen.de [Department of Cardiology, University of Duisburg-Essen, Essen (Germany); Eggebrecht, Holger [Cardioangiological Center Bethanien (CCB), Frankfurt (Germany); Roguin, Ariel [Department of Cardiology, Rambam Medical Center, Haifa (Israel); Schroeder, Erwin [Division of Cardiovascular Medicine, Cliniques Universitaires de Mont-Godinne, Yvoir (Belgium); Philipp, Sebastian [Department Internal Medicine/Cardiology, Elbe Klinikum Stade, Stade (Germany); Heitzer, Thomas [Department of Cardiology, Heart Center Dortmund, Dortmund (Germany); Schwacke, Harald [Department of Internal Medicine, Diakonissen-Stiftungs- Krankenhaus Speyer (Germany); Ayzenberg, Oded [The Heart Institute, Kaplan Medical Center, Rehovot (Israel); Serra, Antonio [Servicio de Cardiología, Hospital de la Santa Creu i Sant Pau, Barcelona, España (Spain); Delarche, Nicolas [Cardiology unit, Pau General Hospital, Pau (France); Luchner, Andreas [Department of Internal Medicine/Cardiology, Universitätsklinikum Regensburg (Germany); Slagboom, Ton [Department of Cardiology, Onze Lieve Vrouwe Gasthuis, Amsterdam (Netherlands)

    2014-11-15

    Background: Novel bare metal stents with improved stent design may become a viable alternative to drug-eluting stents in certain patient groups, particularly, when long-term dual antiplatelet therapy should be avoided. Purpose: The ENERGY registry aimed to assess the safety and benefits of a cobalt–chromium thin strut bare metal stent with a passive coating in a large series of patients under real-world conditions. Methods and materials: This prospective registry recruited 1016 patients with 1074 lesions in 48 centers from April to November 2010. The primary endpoint was the rate of major adverse cardiac events (MACEs), a composite of cardiac death, myocardial infarction and clinically driven target lesion revascularization. Results: More than half of the lesions (61.0%) were type A/B1 lesions, mean lesion length was 14.5 ± 6.5 mm and mean reference vessel diameter 3.2 ± 0.5 mm. MACE rates at 6, 12 and 24 months were 4.9%, 8.1% and 9.4%, target lesion revascularization rates 2.8%, 4.9% and 5.4% and definite stent thrombosis rates 0.5%, 0.6% and 0.6%. Subgroups showed significant differences in baseline and procedural characteristics which did not translate into significantly different clinical outcomes. Specifically, MACE rates at 24 months were 13.5% in diabetics, 8.6% in small stents and 9.6% in acute coronary syndrome patients. Conclusion: The population of ENERGY reflects real-world conditions with bare metal stents being mainly used in simple lesions. In this setting, percutaneous coronary intervention using a cobalt–chromium thin strut bare metal stent with a passive coating showed very good results up to 24 months. (ClinicalTrials.gov:NCT01056120) Summary for annotated table of contents: The ENERGY international registry evaluated the safety and benefits of a cobalt–chromium thin strut bare metal stent with passive coating in 1016 patients under real-world conditions until 2 years. Results were encouraging with a low composite rate of cardiac death

  18. 铸造钴铬合金含银抗菌涂层表面性能及体外细胞毒性研究%Study of Ag-containing on casting cobalt chromium alloy on the surface structure and the cell toxicity in vitro

    Institute of Scientific and Technical Information of China (English)

    赵敏; 梁锐英; 孟贺; 徐艳丽; 李敬东; 吴文慧

    2012-01-01

    目的 检测钴铬合金含银抗菌涂层的表面性能及细胞毒性,为其临床应用提供依据.方法 于钴铬合金表面应用等离子喷涂技术制备含银抗菌涂层(涂层组),通过扫描电镜、能谱分析及X射线衍射分析表面性能.以常规铸造的钴铬合金试件为合金对照组,利用甲基噻唑基四唑法测试涂层组合金浸提液(分为25%、50%、75%和100%亚组)和合金对照组浸提液以及阴性对照组(新鲜培养液)对小鼠成纤维细胞L929增殖的影响(培养1、2、3d);用流式细胞术测试阴性对照组、涂层组和合金对照组培养48 h后L929细胞周期的差异.结果 涂层表面均匀致密,与基底材料未见明显间隙,表层主要物相为Ag、Cr和少量的Ag2O、Cr2O3.细胞培养1、2、3d后,阴性对照组、各涂层亚组和合金对照组A值差异无统计学意义(P>0.05);阴性对照组各时间点毒性评级均为0级,各涂层亚组和合金对照组各时间点毒性评级均为1级.涂层组G2期细胞周期比例为(8.23±0.39)%,合金对照组G2期细胞周期比例为(8.70±0.46)%,两组间差异无统计学意义(P>0.05),显著低于阴性对照组[(24.15±0.71)%].结论 钴铬合金含银涂层结构稳定,与临床常用钴铬合金相比,对L929细胞的增殖及细胞周期影响无明显差异,细胞相容性良好.%Objective To detect cobalt chromium alloy antimicrobial coating silver of the surface structure and the cell toxicity in order to provide a theoretical basis for clinical application.Methods Plasma spraying technique was adopted to prepare cobalt chromium alloy antimicrobial coating silver. Scanning electron microscopy,energy dispersive analysis and X-ray diffraction analysis were used to evaluate the surface properties.The methyl thiazolyl tetrazolium and flow cytometry method was adopted to test the L929 cell proliferation and the influence of the cell cycle. Results The surface of the coating was uniform and compact

  19. Evaluation of safety and efficacy of NexGen – an ultrathin strut and hybrid cell design cobalt-chromium bare metal stent implanted in a real life patient population – the Polish NexGen Registry

    Directory of Open Access Journals (Sweden)

    Krzysztof Milewski

    2016-08-01

    Full Text Available Introduction : Despite the dominance of drug-eluting stents in modern interventional cardiology, there is still a niche for bare metal stents. Aim: The aim of the Polish NexGen registry was to evaluate the safety and efficacy of a new generation cobalt-chromium NexGen stent in a real life patient population. Material and methods : A prospective multi-center registry was conducted in five clinical sites of American Heart of Poland. Three hundred and eighty-three patients who underwent percutaneous coronary intervention (PCI with NexGen stent implantation were included. Clinical follow-up was performed at 1, 6 and 12 months. Additionally, a group of 42 randomly selected patients underwent control angiography at 6 months (10.96% of study population. The primary endpoint was occurrence of target vessel revascularization (TVR at 6-month follow-up. Angiographic endpoints included rates of binary restenosis and late lumen loss at 6-month follow-up based on QCA analysis. Multivessel disease was present in more than 70% of patients, and 52.4% of lesions were complex. The main indications for angiography were non-ST elevation acute coronary syndromes (54.8% and ST elevation myocardial infarction (34.99%. Results : At 6-month follow-up 47 (12.7% patients reached the primary endpoint of TVR. The composite of major acute cardiac event rates at 30-day and 6- and 12-month follow-up was 6.01% (n = 23, 18.5% (n = 69 and 25.21% (n = 92 respectively. Control angiography performed after 6 months showed in-stent late loss of 0.66 ±0.71 mm and a binary restenosis rate of 16.7%. Conclusions : Our study showed that PCI with the NexGen stent is safe and effective at 6- and 12-month follow-up. Angiographic results showed a satisfactory restenosis rate and low late lumen loss.

  20. Comparison of in vivo acute stent recoil between the bioabsorbable everolimus-eluting coronary stent and the everolimus-eluting cobalt chromium coronary stent: insights from the ABSORB and SPIRIT trials.

    Science.gov (United States)

    Tanimoto, Shuzou; Serruys, Patrick W; Thuesen, Leif; Dudek, Dariusz; de Bruyne, Bernard; Chevalier, Bernard; Ormiston, John A

    2007-10-01

    This study sought to evaluate and compare in vivo acute stent recoil of a novel bioabsorbable stent and a metallic stent. The bioabsorbable everolimus-eluting coronary stent (BVS) is composed of a poly-L-lactic acid backbone, coated with a bioabsorbable polymer containing the antiproliferative drug, everolimus, and expected to be totally metabolized and absorbed in the human body. Because the BVS is made from polymer, it may have more acute recoil than metallic stents in vivo. A total of 54 patients, who underwent elective stent implantation for single de novo native coronary artery lesions, were enrolled: 27 patients treated with the BVS and 27 patients treated with the everolimus-eluting cobalt chromium stent (EES). Acute absolute recoil, assessed by quantitative coronary angiography, was defined as the difference between mean diameter of the last inflated balloon at the highest pressure (X) and mean lumen diameter of the stent immediately after the last balloon deflation (Y). Acute percent recoil was defined as (X - Y)/X and expressed as a percentage. Acute absolute recoil of the BVS and EES was 0.20 +/- 0.21 mm and 0.13 +/- 0.21 mm, respectively (P = 0.32). Acute percent recoil was 6.9% +/- 7.0% in the BVS group and 4.3% +/- 7.1% in the EES group (P = 0.25). In vivo acute stent recoil of the BVS is slightly larger but insignificantly different from that of the EES, implying that the BVS may have good radial strength similar to the metallic stent. (c) 2007 Wiley-Liss, Inc.

  1. Efficacy and safety of a biodegradable polymer Cobalt-Chromium sirolimus-eluting stent (EXCEL2) in treating de novo coronary artery disease: A pooled analysis of the CREDIT II and CREDIT III trials.

    Science.gov (United States)

    Wang, Geng; Wang, Heyang; Xu, Bo; Yang, Yuejin; Yang, Zhiming; Li, Hui; Zhang, Zheng; Wang, Haichang; Yang, Lixia; Han, Yaling

    2017-03-01

    The safety and efficacy of the second-generation biodegradable polymer Cobalt-Chromium sirolimus-eluting stent (EXCEL2) in daily clinical practice remains unknown. Additionally, to meet the China Food and Drug Administration requirements, we conducted an objective performance criterion study from the CREDIT II and CREDIT III trials. CREDIT II was a randomized trial comparing the EXCEL2 versus EXCEL stent in patients with up to 2 de novo coronary lesions. CREDIT III was a prospective, single-arm study evaluating the efficacy and safety of EXCEL2 in broad types of de novo coronary artery lesions. This pooled analysis included patients in the CREDIT III and EXCEL2 arm of the CREDIT II trial. The primary outcome was 12-month target lesion failure (TLF), a composite of cardiac death, target vessel myocardial infarction (TV-MI), and clinical indicated target lesion revascularization (CI-TLR). The patient-oriented composite endpoint (PoCE) of all-cause death, all MI, or any revascularization was also analyzed. A total of 833 patients were included, consisting of 625 in the CREDIT III trial and 208 in the EXCEL2 arm of the CREDIT II trial. Twelve-month TLF occurred in 6.1% patients, cardiac death in 0.4%, TV-MI in 5%, and CI-TLR in 1.1%. Additionally, 64 (7.7%) PoCE and 3 probable late stent thromboses (0.4%) were recorded. EXCEL2 stent met the objective performance criterion on efficacy and safety with a low level of 12-month TLF as well as stent thrombosis when treating patients with de novo coronary lesions. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. Comparative evaluation of effect of metal primer and sandblasting on the shear bond strength between heat cured acrylic denture base resin and cobalt-chromium alloy: An in vitrostudy

    Directory of Open Access Journals (Sweden)

    Sandeep Kalra

    2015-01-01

    Full Text Available Aims: The aim of this study was to evaluate the effect of metal primers and sandblasting on the shear bond strength (SBS of heat cured acrylic denture base resin to cobalt-chromium (Co-Cr alloy. Materials and Methods: A total number of 40 disk shaped wax patterns (10 mm in diameter and 2 mm in thickness were cast in Co-Cr alloy. Samples were divided into 4 groups depending on the surface treatment received. Group 1: No surface treatment was done and acts as control group. Group 2: Only sandblasting was done. Group 3: Only metal primer was applied. Group 4: Both metal primer and sandblasting were done. After surface treatment samples had been tested in Universal Testing Machine at crosshead speed of 0.5 mm/min in shear mode and scanning, electron microscope evaluation was done to observe the mode of failure. Statistical Analysis: All the observations obtained were analyzed statistically using software SPSS version 17; one-way analysis of variance (ANOVA and post-hoc Tukey test were applied. Results: The one-way ANOVA indicated that SBS values varied according to type of surface treatment done. The SBS was highest (18.70 ± 1.2 MPa when both sandblasting and metal primer was done when compared with no surface treatment (2.59 ± 0.32 MPa. Conclusions: It could be concluded that the use of metal primers along with sandblasting significantly improves the bonding of heat cured acrylic denture base resin with the Co-Cr alloy.

  3. Optical, X-Ray Diffraction, and Magnetic Properties of the Cobalt-Substituted Nickel Chromium Ferrites (CrCoNi1−FeO4, =0,0.2,0.4,0.6,0.8,1.0 Synthesized Using Sol-Gel Autocombustion Method

    Directory of Open Access Journals (Sweden)

    Sonal Singhal

    2011-01-01

    Full Text Available Cobalt-substituted nickel chromium ferrites (CrCoNi1−FeO4, =0,0.2,0.4,0.6,0.8,1.0 have been synthesized using sol-gel autocombustion method and annealed at 400 °C, 600 °C, 800 °C, and 1000 °C. All the ferrite samples have been characterized using UV-VIS spectrophotometery, FT-IR spectroscopy, Transmission Electron Microscopy, powder X-Ray Diffraction, and magnetic measurements. Typical FT-IR spectra of the samples annealed at 400°C, 600°C, 800°C, and 1000°C exhibit two frequency bands in the range of ~480 cm−1 and ~590 cm−1 corresponding to the formation of octahedral and tetrahedral clusters of metal oxide, respectively. TEM images reveal that crystallite size increases from ~10 nm to ~45 nm as the annealing temperature is increased from 400°C to 1000°C. The unit cell parameter “a” is found to increase on increasing the cobalt concentration due to larger ionic radius of cobalt. Also, as the cobalt concentration increases, the saturation magnetization increases from 4.32 to 19.85 emu/g. This is due to the fact that cobalt ion replaces the less magnetic nickel ions. However, the coercivity decreases with increase in cobalt concentration due to the decrease in anisotropy field. The band gap has been calculated using UV-VIS spectrophotometry and has been found to decrease with the increase of particle size.

  4. Evaluation of the fit of cobalt-chromium crowns fabricated by selective laser melting%选择性激光熔覆(SLM)制作钴铬合金冠的适合性研究

    Institute of Scientific and Technical Information of China (English)

    党玉琪; 张春宝; 王伟娜; 高勃

    2015-01-01

    目的:评价选择性激光熔覆(SLM)技术与失蜡铸造法制作的钴铬合金单冠与三联冠的适合性。方法:采用2种 SLM系统 EOS M270与 EOS M280及铸造法分别制作钴铬合金单冠与三联冠各5个,通过采用硅橡胶法在体式显微镜下测量边缘及内部垂直间隙。采用 SPSS 17.0软件对实验数据进行单因素方差分析。结果:钴铬合金单冠的边缘间隙和内部间隙(μm)分别为:EOS M270组42.28±11.58、125.75±47.67,EOS M280组46.54±8.4、128.22±54.18,铸造组为48.66±12.08、135.37±46.89。三联冠的边缘间隙(μm)和内部间隙(μm)分别为:EOS M270组40.55±10.04、133.09±39.80,EOS M280组45.36±10、138.94±50.61,铸造组为54.24±12.04、151.87±61.94(P <0.05)。结论:SLM组边缘平均垂直间隙明显小于临床普遍接受的120μm 的标准,精度可以满足临床要求。SLM钴铬合金单冠的边缘适合性优于铸造法,内部适合性无统计学差异。SLM钴铬合金三联冠的边缘适合性及内部适合性均优于铸造法。%Objective:To compare the adaption of cobalt-chromium prostheses fabricated by selective laser melting(SLM)and conven-tional lost wax technique(LW)method.Methods:Cobalt-chromium crowns and three-unit fixed dental prostheses(FDPs)were fabrica-ted by selective laser melting(SLM)or by conventional lost wax technique(LW)respectively(n =5).Marginal fit and internal fit were examined using a light-body silicone.After setting,each silicon film was cut into 2 parts and the thickness of silicon layer was measured at 1 00 ×magnification using a digital microscope,the data of marginal gap(MG)and internal gap(IG)were statistically analysed by ANOVA and SPSS statistical package version 1 7.0.Results:The MG and IG(μm)of cobalt-chromium alloy crowns in EOS M270 group were 42.28 ±1 1 .58 and 1 25.75 ±47.67,in EOS M280 group 46.54 ±8.4 and 1 28.22 ±54

  5. Effect of Artificial Saliva and Intraoral Fluoride on the Fatigue Strength and Roughness Values of Chromium- cobalt Alloy Clasp.%人工唾液和氟化物对钴铬合金卡环疲劳强度及粗糙度影响的研究

    Institute of Scientific and Technical Information of China (English)

    刘杰; 赵笺龄; 商维荣

    2011-01-01

    目的:探讨人工唾液和氟化物对钴铬合金卡环疲劳强度及粗糙度的影响.方法:用成品卡环蜡型制作钴铬合金卡环60个,分为6组,分别在空气中、人工唾液和氟化物中进行测试,初始载荷强度和疲劳失效前的载荷循环次数被自动记录;疲劳裂纹和表面形貌进行扫描电镜分析.用精密粗糙度测量仪检测各组表面粗糙度.结果:钴铬合金卡环在不同测试条件下的疲劳强度及粗糙度有差异.统计分析表明,pH5.6NaF处理组与对照组的循环载荷次数有显著性差异(P<0.01).pH5.6NaF处理组在处理前后的粗糙度有显著性差异(P<0.01).结论:人工唾液和氟化物会使钴铬合金卡环的疲劳强度下降,而表面粗糙度升高.%Objective: To study the effect of artificial saliva and intraoral fluoride on the fatigue strength and roughness values of cobalt-chromium alloy clasp. Methods: Sixty casting clasp specimens of cobalt-chromium alloys made from prefabricated wax were divided into 6 groups. Specimens were tested in air, artificial saliva and intraoral fluoride. Initial loading force and loading cycle before fracture were registered automatically. The fatigue corrosion cracks and surface corrosion situation were observed by scanning electron microscopy (SEM). Surface roughness values in different groups were measured by precision topographer. Results.. The fatigue strength and roughness values of chromium-cobalt alloy were not different among six test conditions. StatistiCal analysis showed that there was significant difference between pH5.6NaF group and control group in loading cycle(P<0.01) pH5,6 NaF group had significant difference before and after processing the surface roughness (P<0. 01) Conclusion: Both artificial saliva and intraoral fluoride reduced the fatigue strength of chromium-cobalt alloy, whereas, improved the roughness values.

  6. 264 Chemical Speciation of Chromium in Various Matrices in South ...

    African Journals Online (AJOL)

    Ignacy cukrowski

    ... measurements. Keywords Chromium speciation, waters, adsorptive stripping voltammetry. ..... that of chromium. Boussemart M. et al.16 observed no effect, by addition of cobalt (50 mM), nickel (50 .... The method is very resistant to many ... 31 J.R. Pretty, E.A. Blubaugh, J.A. Caruso and T.M. Davidson, Anal. Chem. 1994,.

  7. Characterization of a Cobalt-Tungsten Interconnect

    DEFF Research Database (Denmark)

    Harthøj, Anders; Holt, Tobias; Caspersen, Michael

    2012-01-01

    A ferritic steel interconnect for a solid oxide fuel cell must be coated in order to prevent chromium evaporation from the steel substrate. The Technical University of Denmark and Topsoe Fuel Cell have developed an interconnect coating based on a cobalt-tungsten alloy. The purpose of the coating...... is to act both as a diffusion barrier for chromium and provide better protection against high temperature oxidation than a pure cobalt coating. This work presents a characterization of a cobalt-tungsten alloy coating electrodeposited on the ferritic steel Crofer 22 H which subsequently was oxidized in air...... of oxidation time. The coating had completely oxidized during the 300 h oxidation time. GDOES measurements showed that the tungsten was located in an inner zone in the coating/substrate interface. The outer layer of the coating did not contain any tungsten after oxidation but consisted mainly of cobalt...

  8. Chromium(VI) release from leather and metals can be detected with a diphenylcarbazide spot test

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl

    2015-01-01

    Along with chromium, nickel and cobalt are the clinically most important metal allergens. However, unlike for nickel and cobalt, there is no validated colorimetric spot test that detects chromium. Such a test could help both clinicians and their patients with chromium dermatitis to identify culprit...... exposures. To evaluate the use of diphenylcarbazide (DPC) as a spot test reagent for the identification of chromium(VI) release. A colorimetric chromium(VI) spot test based on DPC was prepared and used on different items from small market surveys. The DPC spot test was able to identify chromium(VI) release...... at 0.5 ppm without interference from other pure metals, alloys, or leather. A market survey using the test showed no chromium(VI) release from work tools (0/100). However, chromium(VI) release from metal screws (7/60), one earring (1/50), leather shoes (4/100) and leather gloves (6/11) was observed. We...

  9. Análise morfométrica da carótida de suínos submetidos a angioplastia com ou sem implante de stent de cromo-cobalto Morphometric analysis of swine carotid artery angioplasty with or without cobalt-chromium stent implantation

    Directory of Open Access Journals (Sweden)

    João Luiz de Lara Elesbão

    2010-06-01

    Full Text Available Contexto: A hiperplasia intimal é a reação tardia mais comum decorrente da angioplastia. O uso de stents de cromo-cobalto é bem estudado na circulação coronariana, porém não há muitos estudos que abordem o uso desses stents nas circulações carotídea e periférica. Objetivo: Analisar mediante morfometria a reação intimal presente na artéria carótida de suínos submetidos a angioplastia isoladamente e a angioplastia seguida de implante de stent de cromo-cobalto. Materiais e métodos: Em oito suínos, foi realizada angioplastia da artéria carótida comum direita e angioplastia seguida de implante de um stent de cromo-cobalto na artéria carótida comum esquerda. Após 4 semanas, os animais foram submetidos a eutanásia para a retirada de amostras de tecido arterial e preparo de lâminas histológicas. As imagens das lâminas foram digitalizadas e analisadas por programa de morfometria digital. A análise estatística foi realizada através da média e desvio padrão das áreas em cada grupo, utilizando-se o Teste t de Student. O valor de p Background: Intimal hyperplasia is the most common delayed response to angioplasty. The use of cobalt-chromium stents is well studied in the coronary circulation; however, there are few studies on their use in the carotid and peripheral circulation. Objective: To analyze the intimal reaction in a swine carotid artery undergoing simple angioplasty and angioplasty followed by implantation of cobalt-chromium stent. Materials and methods: We carried out angioplasty in the right common carotid artery and angioplasty with cobalt-chromium stent in the left common carotid artery in eight swine. Four weeks later, all animals were sacrificed for arterial tissue sampling and preparation of histological slides. Slide images were scanned and analyzed using a digital morphometry program. Statistical analysis was performed by mean values and standard deviations of the areas in each group, using the Student's t

  10. Cobalt ferrite based magnetostrictive materials for magnetic stress sensor and actuator applications

    Science.gov (United States)

    Jiles, David C. (Inventor); Paulsen, Jason A. (Inventor); Snyder, John E. (Inventor); Lo, Chester C. H. (Inventor); Ring, Andrew P. (Inventor); Bormann, Keith A. (Inventor)

    2008-01-01

    Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals for iron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors and actuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.

  11. Cobalt poisoning

    Science.gov (United States)

    ... against the metal cup when you walk. These metal particles (ions) can get released into the hip socket and ... Cobalt may also be found in: Alloys Batteries Chemistry/crystal ... Magnets Some metal-on-metal hip implants Tires Cobalt was once ...

  12. Effect of processing parameters on hardness of selective laser melting cobalt-chromium alloy%加工参数设置对选择性激光熔积钴铬合金硬度的影响

    Institute of Scientific and Technical Information of China (English)

    张碧楚; 曾丽; 忻贤贞; 魏斌

    2015-01-01

    目的:观测几种加工参数设置对选择性激光熔积(SLM)钴铬合金的表面形貌和表面维氏硬度的影响。方法使用正交实验设计9组不同的加工参数,即激光功率为2500W、2750W、3000W,扫描速度为5mm/s、10mm/s、15mm/s,送粉速率为3r/min、4.5r/min、6r/min,制备9组选择性激光熔积钴铬合金试件,每组5个(直径10mm,厚度3mm),经抛光处理后分别进行扫描电镜观察和表面维氏硬度测试,采用SPSS16.0软件包进行数据处理。结果9组不同加工参数制备下SLM钴铬合金试件的扫描电镜图像均呈现均匀而规则的细胞样结构;其平均表面维氏硬度均在345HV以上。结论当加工参数设置在激光功率2500~3000W,扫描速度5~15mm/s,送粉速率3~6r/min范围内时,SLM钴铬合金具有较为理想的表面形貌和表面硬度,能适合临床应用需求。%Objective To investigate the effects of several processing parameters on surface morphol-ogy and surface hardness of cobalt-chromium(Co-Cr) alloy fabricated by selective laser melting (SLM). Methods Nine groups of selective laser melting Co-Cr alloy were fabricated by different processing parameters (laser power:2500W, 2750W, 3000W;scanning speed:5mm/s, 10mm/s, 15mm/s;power feeding rate:3r/min, 4.5r/min, 6r/min) by orthogonal experiment design, each group has five specimens (10mm diameter and 3mm thickness). The speci-mens’ surface morphology was observed by a scanning electron microscope and their Vickers hardness was mea-sured by micro-hardness tester. The data was analyzed with SPSS16.0 software package. Results The SEM im-ages showed all selective laser melting Co-Cr alloy had a homogeneous and regular cellular structure and the mean surface Vickers hardness were all above 345HV. Conclusion When laser power is set at 2500-3000W, scanning speed is set by 5-15mm/s and power feeding rate is set by 3-6r/min, SLM Co-Cr alloy has both ideal surface prop-erty and surface

  13. 不同金属处理剂对钴铬合金与基托树脂粘结强度的影响%Shear bond strength of polymethyl methacrylate to cobalt-chromium treated with different metal primers

    Institute of Scientific and Technical Information of China (English)

    朱海连; 何升腾; 杨斌

    2013-01-01

    Objective:This study was undertaken to evaluate the shear bond strength of a denture base resin to cobalt-chromium alloy treated with three different adhesive primers.Methods:40 Co-Cr alloy disk (6.0mm diameter,2.5mm thick) were divided into four groups randomly.The surfaces of the disks were sandblasted and laser-induced thermal etching,followed by treatment with 3 different primers (Metal Primer Ⅱ,Estenia Opaque Primer,Metal Base M).A denture base resin was then applied on the disks with hole-punched sticky tape and a Teflon ring.Specimens without primer served as controls.Bonded specimens were stored in 37℃ distilled water for 24 hours,then all the specimens were subjected to shear force in a universal testing machine at a crosshead speed of 0.5mm/min.Results:All of the primers significantly(P<0.05) improved shear bond strengths of denture base resin to the Co-Cr alloy.Specimens treated with Metal Primer Ⅱ and Estenia Opaque Primer showed higher bond strength than treated with Metal Base M (P<0.05).And there was no significant difference between the Metal Primer Ⅱ and Estenia Opaque Primer (P>0.05).Conclusion:These three metal primers could increase the shear bond strength of a denture base resin to the Co-Cr alloy.Metal Primer Ⅱ and Estenia Opaque Primers exhibited greater bond strength improvement than Metal Base M.%目的:研究三种金属处理剂对钴铬合金与基托树脂粘接强度的影响.方法:制备40个钴铬合金试件随机分为4组,采用喷砂和激光对各个试件表面进行处理后,除对照组外,其它组试件分别采用Metal Primer Ⅱ,Estenia Opaque Primer,Metal Base M三种金属处理剂对试件表面进行处理,后将基托树脂与金属试件进行粘接.经37℃恒温水浴24h后,测定金属试件与基托树脂间的剪切粘接强度,并进行统计分析.结果:三种金属处理剂组所获得的钴铬合金与基托树脂间的剪切粘接强度均显著高于对照组(P<0.05).Metal Primer

  14. Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation

    NARCIS (Netherlands)

    Patntirapong, Somying; Habibovic, Pamela; Hauschka, Peter V.

    2009-01-01

    Metal ions originating from mechanical debris and corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+), which is a major component of cobalt–chromium-based implant alloys and a known acti

  15. The Cytotoxicity and Genotoxicity of Particulate and Soluble Cobalt in Human Urothelial Cells.

    Science.gov (United States)

    Speer, Rachel M; The, Therry; Xie, Hong; Liou, Louis; Adam, Rosalyn M; Wise, John Pierce

    2017-03-21

    Cobalt use is increasing particularly due to its use as one of the primary metals in cobalt-chromium-molybdenum (CoCrMo) metal-on-metal prosthetics. CoCrMo is a high-strength, wear-resistant alloy with reduced risk for prosthetic loosening and device fracture. More than 500,000 people receive hip implants each year in the USA which puts them at potential risk for exposure to metal ions and particles released by the prosthetic implants. Data show cobalt ions released from prosthetics reach the bloodstream and accumulate in the bladder. As patients with failed hip implants show increased urinary and blood cobalt levels, no studies have considered the effects of cobalt on human urothelial cells. Accordingly, we investigated the cytotoxic and genotoxic effects of particulate and soluble cobalt in urothelial cells. Exposure to both particulate and soluble cobalt resulted in a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ions. Based on intracellular cobalt ion levels, we found, when compared to particulate cobalt, soluble cobalt was more cytotoxic, but induced similar levels of genotoxicity. Interestingly, at similar intracellular cobalt ion concentrations, soluble cobalt induced cell cycle arrest indicated by a lack of metaphases not observed after particulate cobalt treatment. These data indicate that cobalt compounds are cytotoxic and genotoxic to human urothelial cells and solubility may play a key role in cobalt-induced toxicity.

  16. Sensitization to palladium in Europe

    NARCIS (Netherlands)

    Muris, J.; Goossens, A.; Gonçalo, M.; Bircher, A.J.; Giménez-Arnau, A.; Foti, C.; Bruze, M.; Andersen, K.E.; Rustemeyer, T.; Feilzer, A.J.; Kleverlaan, C.J.

    2015-01-01

    Background Recently, sodium tetrachloropalladate (Na2PdCl4) was found to be a more sensitive palladium patch test allergen than palladium dichloride (PdCl2). Objectives To determine the optimal test concentration of Na2PdCl4, to evaluate the prevalence of palladium sensitization with Na2PdCl4 and Pd

  17. Chemical composition of the ore and occurrence state of the elements in Jingbaoshan platinum- palladium deposit

    Institute of Scientific and Technical Information of China (English)

    SONG Huanbin; HE Mingqin; ZHANG Shangzhong; YI Fenghuang

    2008-01-01

    The Jingbaoshan platinum-palladium deposit is China's largest independent PGM (platinum-group metals) deposit so far discovered. There are eleven kinds of useful components in the ore: Pt, Pd, Os, Ir, Ru, Rh, Au, Ag, Cu, Ni, and Co. The platinum-group elements, gold and silver occur in the form of minerals in ores. twenty-five kinds of precious metal minerals have been found, of which twenty one belong to the platinum-group minerals. The minerals are very small in grain size. Copper occurs mainly as copper sulfide with a small amount of free copper oxide, and the beneficiated copper accounts for 95.21%. Nickel occurs mainly as nickel sulfide, and some nickel silicate and nickel oxide occur in the ore. The beneficiated nickel accounts for 72.03%. Cobalt occurs mainly as cobalt sulfide, and there are some cobalt oxide and other kinds of cobalt. The beneficiated cobalt accounts for 77.58%.

  18. Silver-palladium cathode

    Energy Technology Data Exchange (ETDEWEB)

    Poizot, Philippe [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007, Universite de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Simonet, Jacques, E-mail: jacques.simonet@univ-rennes1.f [Laboratoire MaCSE, UMR CNRS 6226, Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France)

    2010-12-15

    The formation of silver-palladium electrodes is described. It mainly corresponds to the palladization of silver by means of treatment with palladium salts (nitrate and sulphate) in acidic media. Other ways may exist such as the modification of solid conductors like carbons by deposition of a silver-palladium alloy. By using those electrodes in polar aprotic solvents, the one-electron cleavage of carbon-halogen bonds of most alkyl iodides and bromides may yield free alkyl radicals. Coupling and cross-coupling reactions can easily be carried out at such electrodes. The present review aims at discussing the electro-catalytic process as well as providing an update on the state of the art on this new mode of scission regarding carbon-heteroatom bonds.

  19. Consumer leather exposure: an unrecognized cause of cobalt sensitization

    DEFF Research Database (Denmark)

    Thyssen, J.P.; Johansen, Jeanne D.; Jellesen, Morten Stendahl

    2013-01-01

    BACKGROUND: A patient who had suffered from persistent generalized dermatitis for 7 years was diagnosed with cobalt sensitization, and his leather couch was suspected as the culprit, owing to the clinical presentation mimicking allergic chromium dermatitis resulting from leather furniture exposure....... MATERIALS AND METHODS: The cobalt spot test, X-ray fluorescence, inductively coupled plasma mass spectrometry and scanning electron microscopy were used to determine cobalt content and release from the leather couch that caused the dermatitis and from 14 randomly collected samples of furniture leather....... RESULTS: The sample from the patient's leather couch, but none of the 14 random leather samples, released cobalt in high concentrations. Dermatitis cleared when the patient stopped using his couch. CONCLUSIONS: Cobalt is used in the so-called pre-metallized dyeing of leather products. Repeated studies...

  20. Radiochemical separation of Cobalt

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    A method is described for the radiochemical separation of cobalt based on the extraordinary stability of cobalt diethyldithiocarbamate. Interferences are few; only very small amounts of zinc and iron accompany cobalt, which is important in neutron-activation analysis.

  1. Radiochemical separation of Cobalt

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    A method is described for the radiochemical separation of cobalt based on the extraordinary stability of cobalt diethyldithiocarbamate. Interferences are few; only very small amounts of zinc and iron accompany cobalt, which is important in neutron-activation analysis.

  2. Simultaneous determination of arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in fertilizers by microwave acid digestion and inductively coupled plasma-optical emission spectrometry detection: single-laboratory validation of a modification and extension of AOAC 2006.03.

    Science.gov (United States)

    Webb, Sharon; Bartos, James; Boles, Rhonda; Hasty, Elaine; Thuotte, Ethel; Thiex, Nancy J

    2014-01-01

    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 method are a significant increase in laboratory efficiency when compared to the use of both AOAC Methods 965.09 and 2006.03 to achieve the same objective and an enhanced recovery of several metals.

  3. Chromium in diet

    Science.gov (United States)

    The best source of chromium is brewer's yeast. However, many people do not use brewer's yeast because it causes bloating ( abdominal distention ) and nausea . Other good sources of chromium include ...

  4. 选择性激光熔化钴铬合金基底冠与铸造钴铬合金基底冠边缘适合性比较%Evaluation of marginal fit in vitro between selective laser melting deposition basal crowns and cobalt chromium alloy base crowns

    Institute of Scientific and Technical Information of China (English)

    李靖敏; 王维倩; 马婧媛

    2014-01-01

    Objective To evaluate the marginal fit in vitro between selective laser melting deposition basal crowns and cobalt chromi-um alloy casting base crowns.Methods Twenty working dies were created from a single master die and were used to fabricate twenty copings in each as the following groups:A(selective laser melting deposition basal crowns,n=1 0),B(cobalt-chrome alloy basal crown, n=1 0).All the metal copings were fabricated according to manufacturers.The restorations were seated on the master die,and high-reso-lution digital photographs were taken of the marginal area on all four sides.The vertical marginal gap was then measured using a calibra-ted digital software program.Analysis of Variance was used to determine the differences using SPSS 20.0 software package.Results The mean marginal gaps were:group A:(48.20 ±4.61 )μm;group B:(77.90 ±6.26)μm .There was significant difference between two groups.Conclusions The marginal gaps of two different metal copings are clinically acceptable.The selective laser melting deposi-tion copings resulted in smaller marginal gaps than cobalt-chrome copings,which shows that the marginal fit of elective laser melting deposition copings is better than cobalt-chrome copings.%目的:评价选择性激光熔化钴铬合金烤瓷冠和传统铸造钴铬合金烤瓷冠的边缘适合性。方法制作下颌第一磨牙全冠牙体制备标准金属代型1个,复制并灌注石膏模型后,制作选择性激光熔化钴铬合金基底冠和铸造钴铬合金基底冠各10个,依次将其就位于金属标准代型上。在体式显微镜下,对基底冠边缘与金属代型肩台之间的适合度进行观察,用 CCD 数字图像捕捉系统进行成像,并用专业测量软件测量边缘缝隙宽度。最后计算各组10个样本的平均值,采用 SPSS 20.0软件包对数据进行统计学处理。结果选择性激光熔化钴铬合金基底冠和传统铸造钴铬合金基底冠平均

  5. Heterogeneous chromium catalysts

    NARCIS (Netherlands)

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-c

  6. Oxidation of Palladium-Chromium Alloys for High Temperature Applications

    Science.gov (United States)

    Piltch, Nancy D.; Jih-Fen, Lei; Zeller, Mary V.

    1994-01-01

    An alloy consisting of Pd with 13 wt % Cr is a promising material for high temperature applications. High temperature performance is degraded by the oxidation of the material, which is more severe in the fine wires and thin films used for sensor applications than in the bulk. The present study was undertaken to improve our understanding of the physical and chemical changes occurring at these temperatures and to identify approaches to limit oxidation of the alloy. The alloy was studied in both ribbon and wire forms. Ribbon samples were chosen to examine the role of grain boundaries in the oxidation process because of the convenience of handling for the oxidation studies. Wire samples 25 microns in diameter which are used in resistance strain gages were studied to correlate chemical properties with observed electrical, physical, and structural properties. Overcoating the material with a metallic Cr film did prevent the segregation of Pd to the surface; however, it did not eliminate the oxidation of the alloy.

  7. MONTANA PALLADIUM RESEARCH INITIATIVE

    Energy Technology Data Exchange (ETDEWEB)

    Peters, John; McCloskey, Jay; Douglas, Trevor; Young, Mark; Snyder, Stuart; Gurney, Brian

    2012-05-09

    Project Objective: The overarching objective of the Montana Palladium Research Initiative is to perform scientific research on the properties and uses of palladium in the context of the U.S. Department of Energy's Hydrogen, Fuel Cells and Infrastructure Technologies Program. The purpose of the research will be to explore possible palladium as an alternative to platinum in hydrogen-economy applications. To achieve this objective, the Initiatives activities will focus on several cutting-edge research approaches across a range of disciplines, including metallurgy, biomimetics, instrumentation development, and systems analysis. Background: Platinum-group elements (PGEs) play significant roles in processing hydrogen, an element that shows high potential to address this need in the U.S. and the world for inexpensive, reliable, clean energy. Platinum, however, is a very expensive component of current and planned systems, so less-expensive alternatives that have similar physical properties are being sought. To this end, several tasks have been defined under the rubric of the Montana Palladium Research Iniative. This broad swath of activities will allow progress on several fronts. The membrane-related activities of Task 1 employs state-of-the-art and leading-edge technologies to develop new, ceramic-substrate metallic membranes for the production of high-purity hydrogen, and develop techniques for the production of thin, defect-free platinum group element catalytic membranes for energy production and pollution control. The biomimetic work in Task 2 explores the use of substrate-attached hydrogen-producing enzymes and the encapsulation of palladium in virion-based protein coats to determine their utility for distributed hydrogen production. Task 3 work involves developing laser-induced breakdown spectroscopy (LIBS) as a real-time, in situ diagnostic technique to characterize PGEs nanoparticles for process monitoring and control. The systems engineering work in task 4

  8. Cobalt nanoparticles as reusable catalysts for reduction of 4-nitrophenol under mild conditions

    Indian Academy of Sciences (India)

    ARIJIT MONDAL; ASISH MONDAL; BIBHUTOSH ADHIKARY; DEB KUMAR MUKHERJEE

    2017-04-01

    Facile reduction of p-nitrophenol to p-aminophenol by sodium borohydride catalysed by cobalt nanoparticles (CoNPs) has been discussed. A simple approach has been made to synthesize highly active and ordered structures of CoNPs. The air-stable nanoparticles were prepared from cobalt sulphate using tetrabutyl ammonium bromide as surfactant and sodium borohydride as reductant. The cobalt nanocolloids in aqueousmedium were foundto be efficient reusable catalysts for the p-nitrophenol reduction. Palladium nanoparticles prepared from palladium chloride and the same surfactant were found to reduce p-nitrophenol but lose their catalytic efficiency after recovery.Based on chemical and kinetic studies, an attempt has been made to elucidate the mechanism of p-nitrophenol reduction using these nanoclusters.

  9. Dose-dependent cytotoxicity of clinically relevant cobalt nanoparticles and ions on macrophages in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young-Min; Xia Zhidao; Glyn-Jones, Sion; Beard, David; Gill, Harinderjit S; Murray, David W, E-mail: young-min.kwon@ndos.ox.ac.u [Nuffield Department of Orthopaedic Surgery, University of Oxford, Oxford OX3 7LD (United Kingdom)

    2009-04-15

    Despite the satisfactory short-term implant survivorship of metal-on-metal hip resurfacing arthroplasty, periprosthetic soft-tissue masses such as pseudotumours are being increasingly reported. Cytotoxic effects of cobalt or chromium have been suggested to play a role in its aetiology. The aim of this study was to investigate the effects of clinically relevant metal nanoparticles and ions on the viability of macrophages in vitro. A RAW 264.7 murine macrophage cell line was cultured in the presence of either: (1) cobalt, chromium and titanium nanoparticles sized 30-35 nm; or (2) cobalt sulphate and chromium chloride. Two methods were used to quantify cell viability: Alamar Blue assay and Live/Dead assay. The cytotoxicity was observed only with cobalt. Cobalt nanoparticles and ions demonstrated dose-dependent cytotoxic effects on macrophages in vitro: the cytotoxic concentrations of nanoparticles and ions were 1 x 10{sup 12} particles ml{sup -1} and 1000 {mu}M, respectively. The high concentration of cobalt nanoparticles required for cytotoxicity of macrophages in vitro suggests that increased production of cobalt nanoparticles in vivo, due to excessive MoM implant wear, may lead to local adverse biological effects. Therefore, cytotoxicity of high concentrations of metal nanoparticles phagocytosed by macrophages located in the periprosthetic tissues may be an important factor in pathogenesis of pseudotumours.

  10. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    Science.gov (United States)

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  11. 新型钴铬合金可降解涂层西罗莫司洗脱支架在猪冠状动脉过度扩张模型中对新生内膜的影响%A novel biodegradable polymer-coated cobalt-chromium alloy sirolimus-eluting stent:evaluation in a porcine model

    Institute of Scientific and Technical Information of China (English)

    张斌; 陈明; 郑博; 王新刚; 范媛媛; 霍勇

    2014-01-01

    目的:评价L-605钴铬合金支架平台、聚丙交酯-乙交酯(PLGA)共聚物载体西罗莫司药物洗脱支架在小型猪冠状动脉过度扩张模型中的安全性和有效性。方法裸金属支架(BMS,15枚)、已上市可降解涂层西罗莫司药物洗脱支架(EXCEL,21枚)和钴铬合金PLGA共聚物载体西罗莫司药物洗脱支架(Co-P-SES,21枚)分组随机置入30头小型猪的前降支(LAD)28枚,回旋支(LCX)13枚,右冠状动脉(RCA)16枚。术后28 d、91 d及182 d复查冠状动脉造影,评价管腔丢失(LL)等指标后处死动物,进行组织形态学及组织病理学分析。结果术后28 d及91 d,各实验组的管腔丢失、新生内膜面积、炎症积分及内皮化积分差异均无统计学意义,但术后28 d Co-P-SES组在扫描电镜下观察内皮化程度优于EXCEL组;术后182 d,Co-P-SES组与EXCEL组在管腔丢失、炎症积分及内皮化积分中差异均无统计学意义,但在内弹力板环绕面积相似的情况下, Co-P-SES组的管腔面积大于EXCEL组[(4.31±0.94)mm2比(2.62±1.17)mm2,P=0.020)],新生内膜面积小于EXCEL组[(1.87±0.53)mm2比(0.84±0.41)mm2,P=0.004)],差异均有统计学意义。结论在小型猪冠状动脉过度扩张模型中,Co-P-SES的安全性与EXCEL类似,在内皮化及减少新生内膜形成方面可能存在一定优势,有必要进一步临床研究以更好地评价其安全性及有效性。%Objective To assess the safety and efifcacy of a novel biodegradable polymer-coated Cobalt-Chromium alloy sirolimus-eluting stent in a porcine model. Methods Bare metal stents (BMS) (n=15), commercial available EXcellstents (n=21), and Cobalt-Chromium alloy PLAG-coated sirolimus-eluting stents (Co-P-SES) (n=21) were implanted in left anterior descending coronary (LAD, n=28)and left circumflex coronary (LCX, n=13), and right coronary artery (RCA, n=16) of 30 mini-pigs randomly

  12. Fatal cobalt toxicity after total hip arthroplasty revision for fractured ceramic components.

    Science.gov (United States)

    Fox, Kimberly A; Phillips, Todd M; Yanta, Joseph H; Abesamis, Michael G

    2016-11-01

    Post-arthroplasty metallosis, which refers to metallic corrosion and deposition of metallic debris in the periprosthetic soft tissues of the body, is an uncommon complication. Systemic cobalt toxicity post-arthroplasty is extremely rare. The few known fatal cases of cobalt toxicity appear to be a result of replacing shattered ceramic heads with metal-on-metal or metal-on-polyethylene implants. Friction between residual shards of ceramic and cobalt-chromium implants allows release of cobalt into the synovial fluid and bloodstream, resulting in elevated whole blood cobalt levels and potential toxicity. This is a single patient chart review of a 60-year-old woman with prior ceramic-on-ceramic right total hip arthroplasty complicated by fractured ceramic components and metallosis of the joint. She underwent synovectomy and revision to a metal-on-polyethylene articulation. Ten months post-revision, she presented to the emergency department (ED) with right hip pain, dyspnea, worsening hearing loss, metallic dysgeusia, and weight loss. Chest CTA revealed bilateral pulmonary emboli (PE), and echocardiogram revealed new cardiomyopathy with global left ventricular hypokinesis with an ejection fraction (EF) of 35-40% inconsistent with heart strain from PE. Whole blood cobalt level obtained two days into her admission was 424.3 mcg/L and 24-h urine cobalt level was 4830.5 mcg/L. Although the patient initially clinically improved with regard to her PE and was discharged to home on hospital day 5, she returned 10 days later with a right hip dislocation and underwent closed reduction of the hip. The patient subsequently decompensated, developing cardiogenic shock, and respiratory failure. She went into pulseless electrical activity (PEA) and expired. Autopsy revealed an extensive metallic effusion surrounding the right hip prosthesis that tested positive for cobalt (41,000 mcg/L). There was also cobalt in the heart muscle tissue (2.5 mcg/g). A whole blood cobalt level

  13. Electron magnetic resonance investigation of chromium diffusion in yttria powders

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, R.S. de, E-mail: rsbiasi@ime.eb.b [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, Pr. General Tiburcio, 80, 22290-270 Rio de Janeiro, RJ (Brazil); Grillo, M.L.N., E-mail: mluciag@uerj.b [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil)

    2010-03-01

    The electron magnetic resonance (EMR) technique was used to investigate the diffusion of chromium in yttria (Y{sub 2}O{sub 3}) powders. The EMR absorption intensity was measured for several annealing times and three different temperatures of isothermal annealing: 1273, 1323 and 1373 K. The activation temperature for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be E{sub A}=342+-5 kJ mol{sup -1}. This value is larger than the activation energy for the diffusion of chromium in rutile (TiO{sub 2}), periclase (MgO) and cobalt monoxide (CoO) and smaller than the activation energy for the diffusion of chromium in chrysoberyl (BeAl{sub 2}O{sub 4}).

  14. Occupational asthma caused by palladium

    Energy Technology Data Exchange (ETDEWEB)

    Daenen, M.; Rochette, F.; Demedts, M.; Nemery, B. [K.U. Leuven, Pneumology (Belgium); Rogiers, P. [A.Z. St-Lucas, Brugge (Belgium); Walle, C. Van de [Siemens, Oostkamp (Belgium)

    1999-01-01

    Occupational exposure to complex platinum salts is a well-known cause of occupational asthma. Although there is evidence that platinum refinery workers may also be sensitized to other precious metals, such as palladium or rhodium, no instances of occupational asthma due to an isolated sensitization to palladium have been reported. A case is reported of occupational rhinoconjunctivitis and asthma in a previously healthy worker exposed to the fumes of an electroplating bath containing palladium. There was no exposure to platinum. Sensitization to palladium was documented by skin-prick tests. The skin-prick test was positive with Pd(NH{sub 3}){sub 4}Cl{sub 2}, but not with (NH{sub 4}){sub 2}PdCl{sub 4}. Corresponding salts of platinum were all negative. A bronchial provocation test with Pd(NH{sub 34})Cl{sub 2} (0.0001 % for a total of 315 s, followed by 0.001 % for a total of 210 s) led to an early decrease in forced expiratory volume in one second (-35%). A similar exposure (0.001 % for a total of 16 min) in an unrelated asthmatic gave no reaction. This case shows that an isolated sensitization to palladium can occur and that respiratory exposure to palladium is a novel cause of metal-induced occupational asthma. (au) 24 refs.

  15. Cobalt metabolism and toxicology-A brief update

    Energy Technology Data Exchange (ETDEWEB)

    Simonsen, Lars Ole, E-mail: LOSimonsen@dadlnet.dk; Harbak, Henrik; Bennekou, Poul

    2012-08-15

    phase lasting several weeks, and with a significant long-term retention in tissues for several years. In serum cobalt (Co{sup 2+}) binds to albumin, and the concentration of free, ionized Co{sup 2+} is estimated at 5-12% of the total cobalt concentration. In human red cells the membrane transport pathway for cobalt (Co{sup 2+}) uptake appears to be shared with calcium (Ca{sup 2+}), but with the uptake being essentially irreversible as cobalt is effectively bound in the cytosol and is not itself extruded by the Ca-pump. It is tempting to speculate that this could perhaps also be the case in other animal cells. If this were actually the case, the tissue partitioning and biokinetics of cobalt in cells and tissues would be closely related to the uptake of calcium, with cobalt partitioning primarily into tissues with a high calcium turn-over, and with cobalt accumulation and retention in tissues with a slow turn-over of the cells. The occupational cobalt exposure, e.g. in cobalt processing plants and hard-metal industry is well known and has probably been somewhat reduced in more recent years due to improved work place hygiene. Of note, however, adverse reactions to heart and lung have recently been demonstrated following cobalt exposure near or slightly under the current occupational exposure limit. Over the last decades the use of cobalt-chromium hard-metal alloys in orthopedic joint replacements, in particular in metal-on-metal bearings in hip joint arthroplasty, has created an entirely new source of internal cobalt exposure. Corrosion and wear produce soluble metal ions and metal debris in the form of huge numbers of wear particles in nanometric size, with systemic dissemination through lymph and systemic vascular system. This may cause adverse local reactions in peri-prosthetic soft-tissues, and in addition systemic toxicity. Of note, the metal nanoparticles have been demonstrated to be clearly more toxic than larger, micrometer-sized particles, and this has made the

  16. Cobalt metabolism and toxicology--a brief update.

    Science.gov (United States)

    Simonsen, Lars Ole; Harbak, Henrik; Bennekou, Poul

    2012-08-15

    , and with a significant long-term retention in tissues for several years. In serum cobalt (Co(2+)) binds to albumin, and the concentration of free, ionized Co(2+) is estimated at 5-12% of the total cobalt concentration. In human red cells the membrane transport pathway for cobalt (Co(2+)) uptake appears to be shared with calcium (Ca(2+)), but with the uptake being essentially irreversible as cobalt is effectively bound in the cytosol and is not itself extruded by the Ca-pump. It is tempting to speculate that this could perhaps also be the case in other animal cells. If this were actually the case, the tissue partitioning and biokinetics of cobalt in cells and tissues would be closely related to the uptake of calcium, with cobalt partitioning primarily into tissues with a high calcium turn-over, and with cobalt accumulation and retention in tissues with a slow turn-over of the cells. The occupational cobalt exposure, e.g. in cobalt processing plants and hard-metal industry is well known and has probably been somewhat reduced in more recent years due to improved work place hygiene. Of note, however, adverse reactions to heart and lung have recently been demonstrated following cobalt exposure near or slightly under the current occupational exposure limit. Over the last decades the use of cobalt-chromium hard-metal alloys in orthopedic joint replacements, in particular in metal-on-metal bearings in hip joint arthroplasty, has created an entirely new source of internal cobalt exposure. Corrosion and wear produce soluble metal ions and metal debris in the form of huge numbers of wear particles in nanometric size, with systemic dissemination through lymph and systemic vascular system. This may cause adverse local reactions in peri-prosthetic soft-tissues, and in addition systemic toxicity. Of note, the metal nanoparticles have been demonstrated to be clearly more toxic than larger, micrometer-sized particles, and this has made the concept of nanotoxicology a crucial, new

  17. 碱熔—电感耦合等离子体原子发射光谱法测定红土镍矿中硅钙镁铝锰钛铬镍钴%Determination of silicon, calcium, magnesium, aluminium, manganese,titanium, chromium, nickel and cobalt in laterite nickel ore by alkali fusion-inductively coupled plasma atomic emission spectrometry

    Institute of Scientific and Technical Information of China (English)

    高亮

    2013-01-01

    The determination method of nine elements (silicon, calcium, magnesium, aluminium, manganese, titanium, chromium, nickel and cobalt) in laterite nickel ore by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established. The laterite nickel ore sample was fused by anhydrous Na2CO3-H3BO3 mixed flux, then acidified and leached by hydrochloric acid. The high salt atomizer and cyclone chamber were used. Under the selected measurement conditions, the content of nine elements in sample solution was determined by ICP-AES. The influence of salts introduced by matrix iron and sample treatment could be eliminated by matrix matching method. The precision test results showed that, the relative standard deviations (RSD) of elements were smaller than 5 %. The proposed method was applied to the determination of reference material, and the determination results of nine elements were basically consistent with the certified values.%建立了红土镍矿中Si、Ca、Mg、Al、Mn、Ti、Cr、Ni、Co 9种元素的电感耦合等离子体原子发射光谱测定方法.红土镍矿样品用无水Na2CO3-H3BO3混合熔剂熔融,盐酸浸取、酸化,选用高盐雾化器和旋流雾室,在选定的测量条件下,用电感耦合等离子体原子发射光谱法测定试液中9种元素含量.基体铁和处理样品时引入试液中的盐分对测定的影响可以通过基体匹配的方法消除.精密度试验结果表明,样品中各元素测定结果的相对标准偏差小于5%.用本法测定标准样品,9种元素的测定值与认定值基本一致.

  18. Sensitization to palladium in Europe

    DEFF Research Database (Denmark)

    Muris, Joris; Goossens, An; Gonçalo, Margarida

    2015-01-01

    BACKGROUND: Recently, sodium tetrachloropalladate (Na2 PdCl4 ) was found to be a more sensitive palladium patch test allergen than palladium dichloride (PdCl2 ). OBJECTIVES: To determine the optimal test concentration of Na2 PdCl4 , to evaluate the prevalence of palladium sensitization with Na2 Pd......Cl4 and PdCl2 , and to compare the results with nickel sensitization in a European multicentre study. MATERIALS AND METHODS: In addition to the European or national baseline series including NiSO4 ·6H2 0 5% pet., consecutive patients were tested with PdCl2 and Na2 PdCl4 2%, 3% and 4% pet. in eight...... and showed suboptimal reactivity. The prevalence of palladium sensitization doubled with Na2 PdCl4 and was similar to that of nickel. Interestingly, in contrast to nickel sensitization, palladium sensitization was not related to female sex. CONCLUSIONS: Three per cent Na2 PdCl4 pet. is the most suitable...

  19. Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.

    Science.gov (United States)

    Sanpo, Noppakun; Berndt, Christopher C; Wen, Cuie; Wang, James

    2013-03-01

    Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles.

  20. Cobalt sensitization and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P

    2012-01-01

    : This clinical review article presents clinical and scientific data on cobalt sensitization and dermatitis. It is concluded that cobalt despite being a strong sensitizer and a prevalent contact allergen to come up on patch testing should be regarded as a very complex metal to test with. Exposure...... data together with clinical data from metal workers heavily exposed to cobalt suggest that patch-test reactions are sometimes false positive and that patch testers should carefully evaluate their clinical relevance....

  1. NKG2D⁺ IFN-γ⁺ CD8⁺ T cells are responsible for palladium allergy.

    Directory of Open Access Journals (Sweden)

    Mitsuko Kawano

    Full Text Available Nickel, cobalt, and chromium are well known to be causal agents of allergic contact dermatitis. Palladium (Pd can also cause allergic disease and exposure results from wide use of this metal in dental restorations and jewelry. Metal allergy is categorized as a delayed-type hypersensitivity, and metal-responsive T cell clones have been isolated from allergic patients. However, compared to nickel, little is known about the pathology of allergic disease mediated by Pd, and pathogenic T cells are poorly understood. To identify the pathogenic T cells that are responsible for onset of Pd allergy, we enriched metal-responsive lymphocytes by sequential adoptive transfer of involved lymph node cells. Here we show that sequential adoptive transfer gradually increased the incidence and the intensity of Pd allergy, and CD8⁺ T cells are responsible for the disease as CD8⁺ T cell-depleted mice and β2-microglobulin-deficient mice did not develop Pd allergy. In addition, we found that draining lymph node cells skewed toward CD8⁺ T cells in response to Pd challenge in 8th adoptive transferred recipient mice. The CD8⁺ T cells expressed NKG2D, a costimulatory molecule involved in the production of IFN-γ. NKG2D ligand was also induced in Pd-injected tissues. Furthermore, both NKG2D ligand-transgenic mice, where NKG2D is downmodulated, and IFN-γ-deficient mice showed impaired Pd allergy. Taken together, these results indicate that IFN-γ-producing NKG2D⁺ CD8⁺ T cells are responsible for Pd allergy and suggest that NKG2D is a potential therapeutic target for treatment of metal allergy.

  2. Cobalt release from inexpensive jewellery

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten Stendahl; Menné, Torkil

    2010-01-01

    Objectives: The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. Methods: The cobalt spot test was used to assess cobalt release from all items....... Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Results: Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin-cobalt plating on these....... Conclusions: This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future...

  3. Palladium-decorated hydrogen-gas sensors using periodically aligned graphene nanoribbons.

    Science.gov (United States)

    Pak, Yusin; Kim, Sang-Mook; Jeong, Huisu; Kang, Chang Goo; Park, Jung Su; Song, Hui; Lee, Ryeri; Myoung, NoSoung; Lee, Byoung Hun; Seo, Sunae; Kim, Jin Tae; Jung, Gun-Young

    2014-08-13

    Polymer residue-free graphene nanoribbons (GNRs) of 200 nm width at 1 μm pitch were periodically generated in an area of 1 cm(2) via laser interference lithography using a chromium interlayer prior to photoresist coating. High-quality GNRs were evidenced by atomic force microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy measurements. Palladium nanoparticles were then deposited on the GNRs as catalysts for sensing hydrogen gases, and the GNR array was utilized as an electrically conductive path with less electrical noise. The palladium-decorated GNR array exhibited a rectangular sensing curve with unprecedented rapid response and recovery properties: 90% response within 60 s at 1000 ppm and 80% recovery within 90 s in nitrogen ambient. In addition, reliable and repeatable sensing behaviors were revealed when the array was exposed to various gas concentrations even at 30 ppm.

  4. Palladium-Catalysed Coupling Reactions

    NARCIS (Netherlands)

    de Vries, Johannes G.; Beller, M; Blaser, HU

    2012-01-01

    Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems

  5. Occupational cobalt and chromium dermatitis in an offset printing factory.

    Science.gov (United States)

    Spruit, D; Malten, K E

    1975-01-01

    A case history of three offset printers and the atomic absorption analysis of their contact materials is described. Though the factory direction and personnel felt strongly about cooperating in order to combat the disease, it became apparent that the prescribed measures had not been effectively carried out. The chemical analysis of the materials proved to be a necessary supplement to the patch testing procedure.

  6. Palladium interaction with silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, M., E-mail: Marialuisa.Gentile@manchester.ac.uk [Centre for Nuclear Energy Technology (C-NET), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL (United Kingdom); Xiao, P. [Materials Science Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Abram, T. [Centre for Nuclear Energy Technology (C-NET), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2015-07-15

    In this work the palladium interaction with silicon carbide is investigated by means of complementary analytical techniques such as thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Thermoscans were carried out on pellets of palladium, α-SiC and β-SiC high purity powders in the temperature range comprised between 293 K and 1773 K, in order to study the effect of temperature on the palladium-silicon carbide reaction. Thermoscans of α-SiC pellets containing 5 at.%Pd show that during differential calorimetry scans three exothermic peaks occurred at 773 K, 1144 K and 1615 K, while thermoscans of β-SiC pellets containing 3 at.%Pd and 5 at.%Pd do not show peaks. For the pellet α-SiC–5 at.%Pd XRD spectra reveal that the first peak is associated with the formation of Pd{sub 3}Si and SiO{sub 2} phases, while the second peak and the third peak are correlated with the formation of Pd{sub 2}Si phase and the active oxidation of silicon carbide respectively. Thermogravimetry scans show weight gain and weight loss peaks due to the SiO{sub 2} phase formation and the active oxidation. Additionally XPS fittings reveal the development of SiC{sub x}O{sub y} phase during the first exothermic peak up to the temperature of 873 K. The experimental data reveals that alpha silicon carbide is attacked by palladium at lower temperatures than beta silicon carbide and the reaction mechanism between silicon carbide and palladium is strongly affected by silicon carbide oxidation.

  7. Palladium interaction with silicon carbide

    Science.gov (United States)

    Gentile, M.; Xiao, P.; Abram, T.

    2015-07-01

    In this work the palladium interaction with silicon carbide is investigated by means of complementary analytical techniques such as thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Thermoscans were carried out on pellets of palladium, α-SiC and β-SiC high purity powders in the temperature range comprised between 293 K and 1773 K, in order to study the effect of temperature on the palladium-silicon carbide reaction. Thermoscans of α-SiC pellets containing 5 at.%Pd show that during differential calorimetry scans three exothermic peaks occurred at 773 K, 1144 K and 1615 K, while thermoscans of β-SiC pellets containing 3 at.%Pd and 5 at.%Pd do not show peaks. For the pellet α-SiC-5 at.%Pd XRD spectra reveal that the first peak is associated with the formation of Pd3Si and SiO2 phases, while the second peak and the third peak are correlated with the formation of Pd2Si phase and the active oxidation of silicon carbide respectively. Thermogravimetry scans show weight gain and weight loss peaks due to the SiO2 phase formation and the active oxidation. Additionally XPS fittings reveal the development of SiCxOy phase during the first exothermic peak up to the temperature of 873 K. The experimental data reveals that alpha silicon carbide is attacked by palladium at lower temperatures than beta silicon carbide and the reaction mechanism between silicon carbide and palladium is strongly affected by silicon carbide oxidation.

  8. 选择性激光熔化技术制作牙科钴铬合金的电化学腐蚀性能研究%Electrochemical-corrosion behavior of dental cobalt-chromium alloy fabricated by selective laser melting technique

    Institute of Scientific and Technical Information of China (English)

    忻贤贞; 项楠; 陈洁; 徐丹; 魏斌

    2012-01-01

    Objective To investigate the electrochemical-corrosion behavior of a dental cobalt-chromium ( Co-Cr) alloy fabricated by selective laser melting (SLM) under conditions simulating the oral environment. Methods Co-Cr alloy specimens for dental use (cylinder, 10 mm in diameter and 3 mm in thickness) were obtained by fabrication with the same Co-Cr alloy using SLM technique ( SLM group, n = 5) or traditional ca3t technique ( control group, n = 5). The electrochemical-corrosion behavior of the specimens were analysed with the parameter of polarization resistance ( Rp), which was examined with electrochemical impedance spectroscopy tests in an artificial saliva solution with two different pHs ( before diet, 5.0; after diet, 2.5). Results At pH of 5.0, Rp values of SLM group and control group were 4.25 ± 1. 11 and 3. 82 ± 1. 40 respectively, and there was no significant difference between two groups (P > 0.05). AtpHof2.5, R values of SLM group and control group were 5.83 ±0. 88 and 3.49 ±0.83 respectively, and there were significant differences between two groups (P <0. 05). Conclusion Compared with traditional cast technique, dental Co-Cr alloy fabricated by SLM has better anti-corrosion behavior in acid oral environment after diet.%目的 采用针对区域选择性激光熔化(SLM)技术制作钴铬合金口腔修复材料,考量其在特殊口腔环境中的电化学腐蚀性能.方法 选取具有相同成分的钴铬(Co-Cr)合金金属粉末和金属块,分别运用SLM技术(SLM组,n=5)和传统的铸造工艺(对照组,n=5)制作适用于口腔修复的Co-Cr合金试件(圆柱形,直径10 mm,厚度3 mm).模拟特殊口腔环境(未进食pH值为5.0,进食后pH值为2.5),采用电化学交流阻抗谱的方法获取相关拟合数据,根据极化电阻值Rp分析两组试件的耐腐蚀性能.结果当模拟口腔环境中pH值为5.0时,SLM组和对照组的Rp值分别为4.25±1.11和3.82±1.40,组间比较差异无统计学意义(P>0.05);当模

  9. Long-term prognosis of cobalt-chromium sirolimus-eluting stent implantation in patients with coronary heart disease complicated with diabetes mellitus%国人冠心病合并糖尿病患者接受雷帕霉素洗脱钴铬合金支架植入术后的长期预后分析

    Institute of Scientific and Technical Information of China (English)

    潘月毅; 瓦哈甫·马木提; 左武旭; 杨继娥; 张峰; 钱菊英; 葛雷; 周俊; 葛均波

    2016-01-01

    Objective:To evaluate the long-term efficacy and safety of a novel type of cobalt-chromium sirolimus-eluting stent (CoCr-SES) in patients with coronary artery disease (CAD) complicated with diabetes mellitus (DM ) .Methods:A total of 1 045 Chinese patients with DM were enrolled into a prospective ,multicenter registered research and followed up for the incidence of death ,myocardial infarction (MI) ,blood circulation reconstruction and thrombosis (ST) among other events . The primary endpoint was a major adverse cardiovascular event (MACE) ,which was composed of cardiovascular death ,non-fatal myocardial infarction (MI) and target vessel revascularization (TVR) ,with a clinical follow-up of 3 years .Results:During the 3-year follow-up ,among 1 045 cases of coronary heart disease complicated with diabetes mellitus ,the rate of MACE was 10 .0% ,including 41 cases (3 .9% ) of cardiovascular death ,38 cases (3 .6% ) of non-fatal MI and 25 cases (2 .4% ) of TVR . The incidence of stent thrombosis (ST ) was 1 .1% in 3 years ,including 7 cases (0 .7% ) of early ST and 4 cases (0 .4% ) of advanced ST .Conclusions:The incidence of MACE and ST is low in patients with coronary heart disease complicated with diabetes at 3 years after implantation of CoCr-SES ,providing compelling evidence for the wide use of domestic CoCr-SES in patients with coronary heart disease complicated with diabetes .%目的:评价冠心病合并糖尿病患者植入新型雷帕霉素洗脱钴铬合金支架(CoCr-SES )的长期疗效和安全性。方法:以一项前瞻性、多中心注册研究中植入CoCr-SES的1045例糖尿病患者为研究对象,随访该组患者的死亡、心肌梗死(MI)、血运重建和血栓(ST)等事件的发生率。主要终点事件定义为由心血管死亡、非致死性MI和靶血管血运重建(TVR)组成的主要不良心血管事件(M ACE),临床随访时间为3年。结果:在3年随访时,1045例合并有糖尿病的冠心病

  10. Separation of gold, palladium and platinum in chromite by anion exchange chromatography for inductively coupled plasma atomic emission spectrometric analysis

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwang Soon; Lee, Chang Heon; Park, Yeong Jae; Joe, Kih Soo; Kim, Won Ho [KAERI, Taejon (Korea, Republic of)

    2001-08-01

    A study has been carried out on the separation of gold, iridium, palladium, rhodium, ruthenium and platinum in chromite samples and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). The dissolution condition of the minerals by fusion with sodium peroxide was optimized and chromatographic elution behavior of the rare metals was investigated by anion exchange chromatography. Spectral interference of chromium, a matrix of the minerals, was investigated on determination of gold. Chromium interfered on determination of gold at the concentration of 500 mg/L and higher. Gold plus trace amounts of iridium, palladium, rhodium and ruthenium, which must be preconcentrated before ICP-AES was separated by anion exchange chromatography after reducing Cr(VI) to Cr(III) by H{sub 2}O{sub 2}. AuCl{sup -}{sub 4} retained on the resin column was selectively eluted with acetone- HNO{sub 3}-H{sub 2}O as an eluent. In addition, iridium, palladium, rhodium and ruthenium remaining on the resin column were eluted as a group with concentrated HCl. However, platinum was eluted with concentrated HNO{sub 3}. The recovery yield of gold with acetone-HNO{sub 3}-H{sub 2}O was 100.7 {+-} 2.0 % , and the yields of palladium and platinum with concentrated HCl and HNO{sub 3} were 96.1 {+-} 1.8% and 96.6 {+-} 1.3%, respectively. The contents of gold and platinum in a Mongolian chromite sample were 32.6 {+-} 2.2 {mu}g/g and 1.6 {+-} 0.14 {mu}g/g, respectively. Palladium was not detected.

  11. Electrodeposition of Cobalt Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sungbok; Hong, Kimin [Chungnam National Univ., Daejeon (Korea, Republic of)

    2013-03-15

    We developed an electroplating process of cobalt nanowires of which line-widths were between 70 and 200 nm. The plating electrolyte was made of CoSO{sub 4} and an organic additive, dimethyldithiocarbamic acid ester sodium salt (DAESA). DAESA in plating electrolytes had an accelerating effect and reduced the surface roughness of plated cobalt thin films. We obtained void-free cobalt nanowires when the plating current density was 6.25 mA/cm{sup 2} and DAESA concentration was 1 mL/L.

  12. Phosphine modified cobalt hydroformylation

    Energy Technology Data Exchange (ETDEWEB)

    Rensburg, H. van; Tooze, R.P.; Foster, D.F. [Sasol Technology UK, St. Andrews (United Kingdom); Janse van Rensburg, W. [Sasol Technology, Sasolburg (South Africa)

    2006-07-01

    An ongoing challenge in phosphine modified cobalt hydroformylation is the fundamental understanding of the electronic and steric properties of phosphine ligands that influence the selectivity and activity of the catalytic reaction. A series of acyclic and cyclic phosphines have been prepared and tested in phosphine modified cobalt hydroformylation of 1-octene. Molecular modelling on a series of phospholanes showed some interesting theoretical and experimental correlations. We also evaluated the use of N-heterocyclic carbenes as an alternative for phosphines in modified cobalt hydroformylation. (orig.)

  13. Alternatives for hard chromium plating: Nanostructured coatings for severe-service valves

    Energy Technology Data Exchange (ETDEWEB)

    Vernhes, L. [Department of Engineering Physics, Ecole Polytechnique, C.P. 6079, Succ. Centre Ville, Montreal, Quebec, Canada H3C 3A7 (Canada); Velan Inc., 7007 Côte de Liesse, Montreal, Quebec, Canada H4T 1X8 (Canada); Azzi, M. [Department of Mechanical Engineering, Notre Dame University-Louize (Lebanon); Klemberg-Sapieha, J.E., E-mail: jsapieha@polymtl.ca [Department of Engineering Physics, Ecole Polytechnique, C.P. 6079, Succ. Centre Ville, Montreal, Quebec, Canada H3C 3A7 (Canada)

    2013-07-15

    In this paper, a variety of chromium-free protective coatings were evaluated as alternatives for hard chromium (HC) electroplating for valve applications, such as nanostructured cobalt-phosphor (NCP) deposited by electroplating and tungsten/tungsten carbide (W/WC) prepared by chemical vapor deposition. A series of laboratory tests including hardness, micro scratch, pin-on-disk and electrochemical polarization measurements were performed in order to compare the performance of the different coatings. In addition, mechanical resistance and fatigue resistance were evaluated using prototype valves with coated ball under severe tribo-corrosion conditions. It was shown that W/WC coating exhibits superior resistance to wear and corrosion due to high hardness and high resistance to pitting, respectively while NCP exhibits better wear resistance than HC with alumina ball and low corrosion potential which allow to use it as protective (sacrificial) coating. Both nanostructured coatings exhibited attractive tribo-mechanical and functional characteristics compared to hard chromium. - Highlights: • Tungsten/tungsten carbide (W/WC) and cobalt-phosphor (NCP) coatings are compared with hard chromium (HC). • NCP and W/WC offer better tribological properties (wear rate and friction coefficient) than HC. • W/WC has demonstrated a robust corrosion behavior with a breakdown potential greater than 1 V. • NCP and W/WC are potential candidates to replace hard chromium as protective coating.

  14. The in vitro toxicity of cobalt-chrome-molybdenum alloy and its constituent metals.

    Science.gov (United States)

    Evans, E J; Thomas, I T

    1986-01-01

    Cobalt-chrome-molybdenum alloys are widely used in orthopaedic implants. Although they are relatively well tolerated, complications (including loosening and tissue necrosis) still occur and sometimes appear to be due to incomplete biocompatibility of the alloy. To investigate the local effect of the alloy on cells derived from the musculo-skeletal system, primary lines of fibroblastic cells from newborn rats were exposed to powders of cobalt-chrome-molybdenum alloy and its main constituents cobalt, chromium nickel and molybdenum. The toxicity of the metals was determined by counts of total cell number and of abnormal cells at intervals from 2 to 12 d. The alloy was much less toxic than cobalt or nickel and the pattern of toxicity was different for each metal. The results emphasize the difficulty of devising a single tissue culture test of toxicity which will measure the toxicity of any potential implant material.

  15. Worse health-related quality of life and hip function in female patients with elevated chromium levels

    Science.gov (United States)

    Hussey, Daniel K; Madanat, Rami; Donahue, Gabrielle S; Rolfson, Ola; Muratoglu, Orhun K; Malchau, Henrik

    2016-01-01

    Background and purpose Blood metal ion levels can be an indicator for detecting implant failure in metal-on-metal (MoM) hip arthroplasties. Little is known about the effect of bilateral MoM implants on metal ion levels and patient-reported outcomes. We compared unilateral patients and bilateral patients with either an ASR hip resurfacing (HR) or an ASR XL total hip replacement (THR) and investigated whether cobalt or chromium was associated with a broad spectrum of patient outcomes. Patients and methods From a registry of 1,328 patients enrolled in a multicenter prospective follow-up of the ASR Hip System, which was recalled in 2010, we analyzed data from 659 patients (311 HR, 348 THR) who met our inclusion criteria. Cobalt and chromium blood metal ion levels were measured and a 21-item patient-reported outcome measures (PROMs) questionnaire was used mean 6 years after index surgery. Results Using a minimal threshold of ≥7 ppb, elevated chromium ion levels were found to be associated with worse health-related quality of life (HRQoL) (p hip function (p < 0.05) in women. These associations were not observed in men. Patients with a unilateral ASR HR had lower levels of cobalt ions than bilateral ASR HR patients (p < 0.001) but similar levels of chromium ions (p = 0.09). Unilateral ASR XL THR patients had lower chromium and cobalt ion levels (p < 0.005) than bilateral ASR XL THR patients. Interpretation Chromium ion levels of ≥7 ppb were associated with reduced functional outcomes in female MoM patients. PMID:27459602

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

    Science.gov (United States)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus; Menné, Torkil; Johansen, Jeanne D

    2015-02-01

    Cobalt is a strong skin sensitizer and a prevalent contact allergen. Recent studies have recognized exposure to leather articles as a potential cause of cobalt allergy. To examine the association between contact allergy to cobalt and a history of dermatitis resulting from exposure to leather. A questionnaire case-control study was performed: the case group consisted of 183 dermatitis patients with a positive patch test reaction to cobalt chloride and a negative patch test reaction to potassium dichromate; the control group consisted of 621 dermatitis patients who did not react to either cobalt or chromium in patch testing. Comparisons were made by use of a χ(2) -test, Fisher's exact, and the Mann-Whitney test. Logistic regression analyses were used to test for associations while taking confounding factors into consideration. Leather was observed as the most frequent exposure source causing dermatitis in the case group. Although the case group significantly more often reported non-occupational dermatitis caused by leather exposure (p cobalt allergy and dermatitis caused by work-related exposure to leather. Our study suggests a positive association between cobalt allergy and a history of dermatitis caused by non-occupational exposure to leather articles. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Cobalt Cardiomyopathy Secondary to Hip Arthroplasty: An Increasingly Prevalent Problem

    Directory of Open Access Journals (Sweden)

    Russel Tilney

    2017-01-01

    Full Text Available A forty-year-old man experienced worsening heart failure four years following bilateral complicated total hip replacement. His condition was extensively worked up but no underlying pathology was immediately evident. Given the cobalt-chromium alloy component present in the hip arthroplasties, the raised cobalt blood levels, and a fitting clinical picture coupled with radiological findings, the patient underwent right hip revision. Evidence of biotribocorrosion was present on direct visualisation intraoperatively. The patient subsequently experienced symptomatic improvement (NYHA class III to class I and echocardiography showed recovery of ejection fraction. Cobalt exists as a bivalent and trivalent molecule in circulation and produces a cytotoxicity profile similar to nanoparticles, causing neurological, thyroid, and cardiological pathology. Blood levels are not entirely useful as there is no identifiable conversion factor for levels in whole blood, serum, and erythrocytes which seem to act independently of each other. Interestingly cobalt cardiomyopathy is frequently compounded by other possible causes of cardiomyopathy such as alcohol and a link has been postulated. Definitive treatment is revision of the arthroplasty as other treatments are unproven.

  18. Assessment of wrought ASTM F1058 cobalt alloy properties for permanent surgical implants.

    Science.gov (United States)

    Clerc, C O; Jedwab, M R; Mayer, D W; Thompson, P J; Stinson, J S

    1997-01-01

    The behavior of the ASTM F1058 wrought cobalt-chromium-nickel-molybdenum-iron alloy (commonly referred to as Elgiloy or Phynox) is evaluated in terms of mechanical properties, magnetic resonance imaging, corrosion resistance, and biocompatibility. The data found in the literature, the experimental corrosion and biocompatibility results presented in this article, and its long track record as an implant material demonstrate that the cobalt superalloy is an appropriate material for permanent surgical implants that require high yield strength and fatigue resistance combined with high elastic modulus, and that it can be safely imaged with magnetic resonance.

  19. Influence of a cobalt-chromium metal framework on surface roughness and Knoop hardness of visible light-polymerized acrylic resins Influência de estrutura metálica de cobalto-cromo na rugosidade e dureza Knoop superficiais de resinas acrílicas polimerizadas por luz visível

    Directory of Open Access Journals (Sweden)

    Joane Augusto de Souza Júnior

    2006-06-01

    Full Text Available Although visible light-polymerized acrylic resins have been used in removable partial dentures, it is not clear whether the presence of a metal framework could interfere with their polymerization, by possibly reflecting the light and affecting important properties, such as roughness and hardness, which would consequently increase biofilm accumulation. The aim of this study was to compare the roughness and Knoop hardness of a visible light-polymerized acrylic resin and to compare these values to those of water-bath- and microwave-polymerized resins, in the presence of a metal framework. Thirty-six specimens measuring 30.0 x 4.0 ± 0.5 mm of a microwave- (Onda Cryl, a visible light- (Triad and a water-bath-polymerized (Clássico (control acrylic resins containing a cobalt-chromium metal bar were prepared. After processing, specimens were ground with 360 to 1000-grit abrasive papers in a polishing machine, followed by polishing with cloths and 1-µm diamond particle suspension. Roughness was evaluated using a profilometer (Surfcorder SE 1700 and Knoop hardness (Kg/mm² was assayed using a microhardness tester (Shimadzu HMV 2000 at distances of 50, 100, 200, 400 and 800 µm from the metal bar. Roughness and Knoop hardness means were submitted to two-way ANOVA and compared by Tukey and Kruskal Wallis tests at a 5% significance level Statistically significant differences were found (p0.05. Within the limitations of this in vitro study, it was concluded that the presence of metal did not influence roughness and hardness values of any of the tested acrylic resins.Resinas acrílicas polimerizadas por luz visível têm sido indicadas para a confecção de próteses parciais removíveis. Entretanto, não há estudos determinando se a presença de estrutura metálica interfere ou não na polimerização, considerando que essa estrutura pode refletir a luz e afetar propriedades como rugosidade e dureza e, consequentemente, facilitar o acúmulo de biofilme

  20. Halogenation of cobalt dicarbollide

    Science.gov (United States)

    Hurlburt, Paul K.; Abney, Kent D.; Kinkead, Scott A.

    1997-01-01

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10' positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron.

  1. cobalt (ii), nickel (ii)

    African Journals Online (AJOL)

    DR. AMINU

    ABSTRACT. The manganese (II), cobalt (II), nickel (II) and copper (II) complexes of N, N' – ... temperature and coordinated water were determined ... indicating fairly stable complex compounds (Table 1). The complex compounds are insoluble [Table 2] in water and common organic solvents, but are readily soluble in ...

  2. Groundwater contaminant by hexavalent chromium

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, C. [Univ. of Texas, Austin, TX (United States)

    1995-11-01

    Oxidation of trivalent chromium to hexavalent chromium has been investigated as a function of total manganese in soils as well as various incubation conditions. Chromium and manganese contents were analyzed by atomic absorption (graphite furnace and flame emission respectively) following acid digestion. Total hexavalent chromium generation capacity was determined by addition of 0.001 M CrCL3, incubation, and analysis by s-diphenyl carbazide. Samples were then leached with CaSO{sub 4} and MgSO{sub 4} and incubated in various environments (oven, freeze-drier, field moist, ultrafreeze) to test for geogenic generation of Cr(IV). The degree of geogenic generation of hexavalent chromium was compared with total Mn and Cr content as well as hexavalent generational capacity.

  3. On texture formation of chromium electrodeposits

    DEFF Research Database (Denmark)

    Nielsen, Christian Bergenstof; Leisner, Peter; Horsewell, Andy

    1998-01-01

    The microstructure, texture and hardness of electrodeposited hard, direct current (DC) chromium and pulsed reversed chromium has been investigated. These investigations suggest that the growth and texture of hard chromium is controlled by inhibition processes and reactions. Further, it has been...... established that codeposition of Cr2O3 nanoparticles is a general feature of DC chromium electrodeposition....

  4. Palladium catalysis for energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferle, L. D.; Datye, Abhaya

    2001-03-01

    Palladium (Pd) is an attractive catalyst for a range of new combustion applications comprising primary new technologies for future industrial energy needs, including gas turbine catalytic combustion, auto exhaust catalysts, heating and fuel cells. Pd poses particular challenges because it changes both chemical state and morphology as a function of temperature and reactant environment and those changes result in positive and negative changes in activity. Interactions with the support, additives, water, and contaminants as well as carbon formation have also been observed to affect Pd catalyst performance. This report describes the results of a 3.5 year project that resolves some of the conflicting reports in the literature about the performance of Pd-based catalysis.

  5. Palladium-mediated intracellular chemistry

    Science.gov (United States)

    Yusop, Rahimi M.; Unciti-Broceta, Asier; Johansson, Emma M. V.; Sánchez-Martín, Rosario M.; Bradley, Mark

    2011-03-01

    Many important intracellular biochemical reactions are modulated by transition metals, typically in the form of metalloproteins. The ability to carry out selective transformations inside a cell would allow researchers to manipulate or interrogate innumerable biological processes. Here, we show that palladium nanoparticles trapped within polystyrene microspheres can enter cells and mediate a variety of Pd0-catalysed reactions, such as allylcarbamate cleavage and Suzuki-Miyaura cross-coupling. The work provides the basis for the customization of heterogeneous unnatural catalysts as tools to carry out artificial chemistries within cells. Such in cellulo synthesis has potential for a plethora of applications ranging from cellular labelling to synthesis of modulators or inhibitors of cell function.

  6. Palladium catalyzed hydrogenation of bio-oils and organic compounds

    Science.gov (United States)

    Elliott, Douglas C.; Hu, Jianli; Hart, Todd R.; Neuenschwander, Gary G.

    2008-09-16

    The invention provides palladium-catalyzed hydrogenations of bio-oils and certain organic compounds. Experimental results have shown unexpected and superior results for palladium-catalyzed hydrogenations of organic compounds typically found in bio-oils.

  7. Elicitation threshold of cobalt chloride

    DEFF Research Database (Denmark)

    Fischer, Louise A; Johansen, Jeanne D; Voelund, Aage

    2016-01-01

    BACKGROUND: Cobalt is a strong skin sensitizer (grade 5 of 5 in the guinea-pig maximization test) that is used in various industrial and consumer applications. To prevent sensitization to cobalt and elicitation of allergic cobalt dermatitis, information about the elicitation threshold level...... of cobalt is important. OBJECTIVE: To identify the dermatitis elicitation threshold levels in cobalt-allergic individuals. MATERIALS AND METHODS: Published patch test dose-response studies were reviewed to determine the elicitation dose (ED) levels in dermatitis patients with a previous positive patch test...... reaction to cobalt. A logistic dose-response model was applied to data collected from the published literature to estimate ED values. The 95% confidence interval (CI) for the ratio of mean doses that can elicit a reaction in 10% (ED(10)) of a population was calculated with Fieller's method. RESULTS...

  8. Cobalt sorption in silica-pillared clays.

    Science.gov (United States)

    Sampieri, A; Fetter, G; Bosch, P; Bulbulian, S

    2006-01-03

    Silicon pillared samples were prepared following conventional and microwave irradiation methods. The samples were characterized and tested in cobalt sorption. Ethylenediammine was added before cobalt addition to improve the amount of cobalt retained. The amount of cobalt introduced in the original clay in the presence of ethylenediammine was the highest. In calcined pillared clays the cobalt retention with ethylenediammine was lower (ca. 40%). In all cases the presence of ethylenediammine increased twice the amount of cobalt sorption measured for aqueous solutions.

  9. Bioaccessibility testing of cobalt compounds.

    Science.gov (United States)

    Stopford, Woodhall; Turner, John; Cappellini, Danielle; Brock, Tom

    2003-08-01

    Testing of metal compounds for solubility in artificial fluids has been used for many years to assist determining human health risk from exposure to specific compounds of concern. In lieu of obtaining bioavailability data from samples of urine, blood, or other tissues, these studies measured solubility of compounds in various artificial fluids as a surrogate for bioavailability. In this context, the measurement of metal "bioaccessibility" can be used as an in vitro substitute for measuring metal bioavailability. Bioaccessibility can be defined as a value representing the availability of metal for absorption when dissolved in in vitro surrogates of body fluids or juices. The aim of this study was to measure and compare the bioaccessibility of selected cobalt compounds in artificial human tissue fluids and human serum. A second aim was to initiate studies to experimentally validate an in vitro methodology that would provide a conservative estimate of cobalt bioavailability in the assessment of dose from human exposure to various species of cobalt compounds. This study evaluated the bioaccessibility of cobalt(II) from 11 selected cobalt compounds and an alloy in 2 physical forms in 5 surrogate human tissue fluids and human serum. Four (4) separate extraction times were used up to 72 hours. The effect of variables such as pH, dissolution time, and mass-ion effect on cobalt bioaccessibility were assessed as well. We found that the species of cobalt compound as well as the physico-chemical properties of the surrogate fluids, especially pH, had a major impact on cobalt solubility. Cobalt salts such as cobalt(II) sulfate heptahydrate were highly soluble, whereas cobalt alloys used in medical implants and cobalt aluminate spinels used as pigments, showed minimal dissolution over the period of the assay.

  10. Cobalt ion-containing epoxies

    Science.gov (United States)

    Stoakley, D. M.; St.clair, A. K.

    1983-01-01

    Varying concentrations of an organometallic cobalt complex were added to an epoxy system currently used by the aerospace industry as a composite matrix resin. Methods for combining cobalt (III) acetylacetonate with a tetraglycidyl 4,4 prime - diaminodiphenylmethane-based epoxy were investigated. The effects of increasing cobalt ion concentration on the epoxy cure were demonstrated by epoxy gel times and differential scanning calorimetry cure exotherms. Analysis on cured cobalt-containing epoxy castings included determination of glass transition temperatures by thermomechanical analysis, thermooxidative stabilities by thermogravimetric analysis, and densities in a density gradient column. Flexural strength and stiffness were also measured on the neat resin castings.

  11. Progress of Palladium Alloy Membranes in Hydrogen Energy

    Institute of Scientific and Technical Information of China (English)

    MA Guang; LI Jin; LI Yin'e; SUN Xiaoliang; CAO Qigao; JIA Zhihua

    2012-01-01

    Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability,perm-selectivity and thermal stability.This paper review the principle of hydrogen permeation,type of alloys and the fabrication methods.At last,the progress and achievements on palladium alloy membranes by Northwest Institute for Non-Ferrous Metal Research are emphasized.

  12. Unexpectedly high uptake of palladium by bituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, J. [Research Lab. for Mining Chemistry, Hungarian Academy of Sciences, Miskolc-Egyetemvaros (Hungary); Brown, S.D.; Snape, C.E. [Univ. of Strathclyde, Dept. of Pure and Applied Chemistry, Glasgow (United Kingdom)

    1997-12-31

    The uptake of palladium as a conversion catalyst onto coals of different rank was investigated. Palladium fixation occurs by a different mode to that for alkaline earth and first row transition metals. Therefore, the dispersion of relatively high concentration of palladium by an ion sorption process is even possible for bituminous coals. (orig.)

  13. Chromium isotopes as indicators of hexavalent chromium reduction

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Thomas M.

    2012-03-20

    This is the final report for a university research project which advanced development of a new technology for identifying chemical reduction of hexavalent chromium contamination in groundwater systems. Reduction renders mobile and toxic hexavalent chromium immobile and less toxic. The new method uses stable isotope ratio measurements, which are made using multicollector ICP-mass spectrometry. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.

  14. The increase in cobalt release in metal-on-polyethylene hip bearings in tests with third body abrasives.

    Science.gov (United States)

    de Villiers, Danielle; Traynor, Alison; Collins, Simon N; Shelton, Julia C

    2015-09-01

    Hypersensitivity reactions in patients receiving metal-on-metal hip replacements have been attributed to corrosion products as observed by elevated cobalt and chromium ions in the blood. Although the majority of cases are reported in metal-on-metal, incidences of these reactions have been reported in the metal-on-polyethylene patient population. To date, no in vitro study has considered cobalt release for this bearing combination. This study considered four 28 mm and seven 52 mm diameter metal-on-polyethylene bearings tested following ISO standard hip simulator conditions as well as under established abrasive conditions. These tests showed measurable cobalt in all bearings under standard conditions. Cobalt release, as well as polyethylene wear, increased with diameter, increasing from 52 to 255 ppb. The introduction of bone cement particles into the articulation doubled polyethylene wear and cobalt release while alumina particles produced significant damage on the heads demonstrated by cobalt levels of 70,700 ppb and an increased polyethylene wear from a mean value of 9-160 mm(3)/mc. Cobalt release was indicative of head damage and correlated with polyethylene wear at the next gravimetric interval. The removal of third body particles resulted in continued elevated cobalt levels in the 52 mm diameter bearings tested with alumina compared to standard conditions but the bearings tested with bone cement particles returned to standard levels. The polyethylene wear in the bone cement tested bearings also recovered to standard levels, although the alumina tested bearings continued to wear at a higher rate of 475 mm(3)/mc. Cobalt release was shown to occur in metal-on-polyethylene bearings indicating damage to the metal head resulting in increased polyethylene wear. While large diameter metal-on-polyethylene bearings may provide an increased range of motion and a reduced dislocation risk, increased levels of cobalt are likely to be released and this needs to be fully

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

    Directory of Open Access Journals (Sweden)

    Guidi Gian

    2006-07-01

    Full Text Available Abstract Background Blood doping is commonplace in competitive athletes who seek to enhance their aerobic performances through illicit techniques. Presentation of the hypothesis Cobalt, a naturally-occurring element with properties similar to those of iron and nickel, induces a marked and stable polycythemic response through a more efficient transcription of the erythropoietin gene. Testing the hypothesis Although little information is available so far on cobalt metabolism, reference value ranges or supplementation in athletes, there is emerging evidence that cobalt is used as a supplement and increased serum concentrations are occasionally observed in athletes. Therefore, given the athlete's connatural inclination to experiment with innovative, unfair and potentially unhealthy doping techniques, cobalt administration might soon become the most suited complement or surrogate for erythropoiesis-stimulating substances. Nevertheless, cobalt administration is not free from unsafe consequences, which involve toxic effects on heart, liver, kidney, thyroid and cancer promotion. Implications of the hypothesis Cobalt is easily purchasable, inexpensive and not currently comprehended within the World Anti-Doping Agency prohibited list. Moreover, available techniques for measuring whole blood, serum, plasma or urinary cobalt involve analytic approaches which are currently not practical for antidoping laboratories. Thus more research on cobalt metabolism in athletes is compelling, along with implementation of effective strategies to unmask this potentially deleterious doping practice

  16. CHROMIUM STATUS IN DIABETES MELLITUS

    Directory of Open Access Journals (Sweden)

    Keshavarz

    1996-06-01

    Full Text Available Fasting serum chromium, total cholesterol HDL-cholesterol, LDL-cholesterol, triacytglycerot and blood sugar were determined in fifty two diabetic patients with no other organic diseases anil compared with those obtained from a control group including fourty two healthy volunteers matched for age, sex ami body mass irutex (BMI. Fasting serum chromium and HDL-cholesterol were significantly lower in patients than in controls (p<0.0001 and p<0.001 respectively, but the mean triacytglycerot concentration was significantly higher in patients than in controls (p<002. Mean total cholesterol and LDL-cholesterol values were not significantly different in the two groups. Mean intake of energy, proteins, fats and chromium, estimated by the 24 hr dietary recall method were not significantly different in the two groups. We demonstrated that despite an adequate intake of chromium, the fasting serum chromium was lower in diabetic patients than in control subjects. Chromium deficiency in diabetic patients may act as a contributing factor in aggravating the disease's complications.

  17. Nickel, cobalt, and their alloys

    CERN Document Server

    2000-01-01

    This book is a comprehensive guide to the compositions, properties, processing, performance, and applications of nickel, cobalt, and their alloys. It includes all of the essential information contained in the ASM Handbook series, as well as new or updated coverage in many areas in the nickel, cobalt, and related industries.

  18. Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Wang, Deli; Liu, Sufen; Wang, Jie; Lin, Ruoqian; Kawasaki, Masahiro; Rus, Eric; Silberstein, Katharine E.; Lowe, Michael A.; Lin, Feng; Nordlund, Dennis; Liu, Hongfang; Muller, David A.; Xin, Huolin L.; Abruña, Héctor D.

    2016-01-01

    Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd–Co–Cu lattice and distributes uniformly within the particles. The uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications. PMID:27336795

  19. Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Wang, Deli; Liu, Sufen; Wang, Jie; Lin, Ruoqian; Kawasaki, Masahiro; Rus, Eric; Silberstein, Katharine E.; Lowe, Michael A.; Lin, Feng; Nordlund, Dennis; Liu, Hongfang; Muller, David A.; Xin, Huolin L.; Abruña, Héctor D.

    2016-06-01

    Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd-Co-Cu lattice and distributes uniformly within the particles. The uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications.

  20. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  1. Californium Recovery from Palladium Wire

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-08-01

    The recovery of 252Cf from palladium-252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, which ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.

  2. Californium Recovery from Palladium Wire

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-08-01

    The recovery of 252Cf from palladium-252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, which ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.

  3. Cobalt source calibration

    Energy Technology Data Exchange (ETDEWEB)

    Rizvi, H.M.

    1999-12-03

    The data obtained from these tests determine the dose rate of the two cobalt sources in SRTC. Building 774-A houses one of these sources while the other resides in room C-067 of Building 773-A. The data from this experiment shows the following: (1) The dose rate of the No.2 cobalt source in Building 774-A measured 1.073 x 10{sup 5} rad/h (June 17, 1999). The dose rate of the Shepherd Model 109 Gamma cobalt source in Building 773-A measured 9.27 x 10{sup 5} rad/h (June 25, 1999). These rates come from placing the graduated cylinder containing the dosimeter solution in the center of the irradiation chamber. (2) Two calibration tests in the 774-A source placed the graduated cylinder with the dosimeter solution approximately 1.5 inches off center in the axial direction. This movement of the sample reduced the measured dose rate 0.92% from 1.083 x 10{sup 5} rad/h to 1.073 x 10{sup 5} rad/h. and (3) A similar test in the cobalt source in 773-A placed the graduated cylinder approximately 2.0 inches off center in the axial direction. This change in position reduced the measured dose rate by 10.34% from 1.036 x 10{sup 6} to 9.27 x 10{sup 5}. This testing used chemical dosimetry to measure the dose rate of a radioactive source. In this method, one determines the dose by the chemical change that takes place in the dosimeter. For this calibration experiment, the author used a Fricke (ferrous ammonium sulfate) dosimeter. This solution works well for dose rates to 10{sup 7} rad/h. During irradiation of the Fricke dosimeter solution the Fe{sup 2+} ions ionize to Fe{sup 3+}. When this occurs, the solution acquires a slightly darker tint (not visible to the human eye). To determine the magnitude of the change in Fe ions, one places the solution in an UV-VIS Spectrophotometer. The UV-VIS Spectrophotometer measures the absorbency of the solution. Dividing the absorbency by the total time (in minutes) of exposure yields the dose rate.

  4. Palladium nanoparticles obtained by mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Sampedro, B.; Hernando, A. [Instituto de Magnetismo Aplicado (RENFE-UCM-CSIC), P.O. Box 155, 28230 Las Rozas, Madrid (Spain); Dpto. Fisica de Materiales, UCM, 28040 Madrid (Spain); Rojas, T.C.; Fernandez, A. [Instituto de Ciencia de Materiales de Sevilla, Centro mixto CSIC-UNIV, 41092 Sevilla (Spain)

    2006-05-15

    Opposed to the existing chemical methods, we have used a physical one in order to obtain palladium nanoparticles. In this work we present the HRTEM observation of Pd nanoparticles obtained by mechanical milling. These particles are around 6 nm in size. The Pd milled samples have exhaustively been structurally characterized. We have also studied its magnetic properties as a function of the milling time and magnetic measurements are according to those previously carried out by us in palladium nanoparticles obtained by chemical methods. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Highly Concentrated Palladium Hydrides/Deuterides; Theory

    Energy Technology Data Exchange (ETDEWEB)

    Papaconstantopoulos, Dimitrios

    2013-11-26

    Accomplishments are reported in these areas: tight-binding molecular dynamics study of palladium; First-principles calculations and tight-binding molecular dynamics simulations of the palladium-hydrogen system; tight-binding studies of bulk properties and hydrogen vacancies in KBH{sub 4}; tight-binding study of boron structures; development of angular dependent potentials for Pd-H; and density functional and tight-binding calculations for the light-hydrides NaAlH4 and NaBH4

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

    Science.gov (United States)

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

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

  7. Palladium-Catalyzed Intramolecular Aminofluorination of Styrenes%Palladium-Catalyzed Intramolecular Aminofluorination of Styrenes

    Institute of Scientific and Technical Information of China (English)

    徐涛; 邱水发; 刘国生

    2011-01-01

    A novel palladium-catalyzed intramolecular oxidative aminofluorination of styrenes has been developed by using NFSI as fluorinating reagent. This reaction represented an efficient method for the synthesis of 2-aryl-3-fluoropyrrolidine derivatives.

  8. Recycling cobalt from spent lithium ion battery

    Institute of Scientific and Technical Information of China (English)

    Zhi-dong XIA; Xiao-qian XIE; Yao-wu SHI; Yong-ping LEI; Fu GUO

    2008-01-01

    Spent lithium ion battery is a useful resource of cobalt. In this paper, cobalt was recovered by a chemical process based upon the analysis of the structure and com-position of the lithium ion battery. X-ray diffraction results show that cobalt oxalate and cobaltous sulfate have been obtained in two different processes. Compared with the cobaltous oxalate process, the cobaltous sulfate process was characterized by less chemical substance input and a cobalt recovery rate of as much as 88%. A combination of these two processes in the recycling industry may win in the aspects of compact process and high recovery rate.

  9. Viral-templated Palladium Nanocatalysts

    Science.gov (United States)

    Yang, Cuixian

    Despite recent progress on nanocatalysis, there exist several critical challenges in simple and readily controllable nanocatalyst synthesis including the unpredictable particle growth, deactivation of catalytic activity, cumbersome catalyst recovery and lack of in-situ reaction monitoring. In this dissertation, two novel approaches are presented for the fabrication of viral-templated palladium (Pd) nanocatalysts, and their catalytic activities for dichromate reduction reaction and Suzuki Coupling reaction were thoroughly studied. In the first approach, viral template based bottom-up assembly is employed for the Pd nanocatalyst synthesis in a chip-based format. Specifically, genetically displayed cysteine residues on each coat protein of Tobacco Mosaic Virus (TMV) templates provide precisely spaced thiol functionalities for readily controllable surface assembly and enhanced formation of catalytically active Pd nanoparticles. Catalysts with the chip-based format allow for simple separation and in-situ monitoring of the reaction extent. Thorough examination of synthesis-structure-activity relationship of Pd nanoparticles formed on surface-assembled viral templates shows that Pd nanoparticle size, catalyst loading density and catalytic activity of viral-templated Pd nanocatalysts can be readily controlled simply by tuning the synthesis conditions. The viral-templated Pd nanocatalysts with optimized synthesis conditions are shown to have higher catalytic activity per unit Pd mass than the commercial Pd/C catalysts. Furthermore, tunable and selective surface assembly of TMV biotemplates is exploited to control the loading density and location of Pd nanocatalysts on solid substrates via preferential electroless deposition. In addition, the catalytic activities of surface-assembled TMV-templated Pd nanocatalysts were also investigated for the ligand-free Suzuki Coupling reaction under mild reaction conditions. The chip-based format enables simple catalyst separation and

  10. Palladium-Catalyzed Asymmetric Quaternary Stereocenter Formation

    NARCIS (Netherlands)

    Gottumukkala, Aditya L.; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G.; Minnaard, Adriaan J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of beta,beta-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and pr

  11. Palladium-catalyzed asymmetric quaternary stereocenter formation

    NARCIS (Netherlands)

    Gottumukkala, A.L.; Matcha, K.; Lutz, M.; de Vries, J.G.; Minnaard, A.J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and provides

  12. Palladium-catalyzed asymmetric quaternary stereocenter formation

    NARCIS (Netherlands)

    Gottumukkala, A.L.; Matcha, K.; Lutz, M.|info:eu-repo/dai/nl/304828971; de Vries, J.G.; Minnaard, A.J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and provides

  13. Clay Aerogel Supported Palladium Nanoparticles as Catalysts

    Directory of Open Access Journals (Sweden)

    Jared J. Griebel

    2016-04-01

    Full Text Available Highly porous, low density palladium nanoparticle/clay aerogel materials have been produced and demonstrated to possess significant catalytic activity for olefin hydrogenation and isomerization reactions at low/ambient pressures. This technology opens up a new route for the production of catalytic materials.

  14. Palladium-Catalyzed Asymmetric Quaternary Stereocenter Formation

    NARCIS (Netherlands)

    Gottumukkala, Aditya L.; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G.; Minnaard, Adriaan J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of beta,beta-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and pr

  15. Chromium at High Pressure

    Science.gov (United States)

    Jaramillo, Rafael

    2012-02-01

    Chromium has long served as the archetype of spin density wave magnetism. Recently, Jaramillo and collaborators have shown that Cr also serves as an archetype of magnetic quantum criticality. Using a combination of x-ray diffraction and electrical transport measurements at high pressures and cryogenic temperatures in a diamond anvil cell, they have demonstrated that the N'eel transition (TN) can be continuously suppressed to zero, with no sign of a concurrent structural transition. The order parameter undergoes a broad regime of exponential suppression, consistent with the weak coupling paradigm, before deviating from a BCS-like ground state within a narrow but accessible quantum critical regime. The quantum criticality is characterized by mean field scaling of TN and non mean field scaling of the transport coefficients, which points to a fluctuation-induced reconstruction of the critical Fermi surface. A comparison between pressure and chemical doping as means to suppress TN sheds light on different routes to the quantum critical point and the relevance of Fermi surface nesting and disorder at this quantum phase transition. The work by Jaramillo et al. is broadly relevant to the study of magnetic quantum criticality in a physically pure and theoretically tractable system that balances elements of weak and strong coupling. [4pt] [1] R. Jaramillo, Y. Feng, J. Wang & T. F. Rosenbaum. Signatures of quantum criticality in pure Cr at high pressure. Proc. Natl. Acad. Sci. USA 107, 13631 (2010). [0pt] [2] R. Jaramillo, Y. Feng, J. C. Lang, Z. Islam, G. Srajer, P. B. Littlewood, D. B. McWhan & T. F. Rosenbaum. Breakdown of the Bardeen-Cooper-Schrieffer ground state at a quantum phase transition. Nature 459, 405 (2009).

  16. Chromium Salen Mediated Alkene Epoxidation

    DEFF Research Database (Denmark)

    Petersen, Kaare Brandt; Norrby, Per-Ola; Daly, Adrian M.;

    2002-01-01

    The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall......, the studies show that the reactions have many similarities, but also a few critical differences. In agreement with experiment, the chromium system requires a change from low- to high-spin in the catalytic cycle, whereas the manganese system can proceed either with spin inversion or entirely on the high......-spin surface. The low-spin addition of metal oxo species to an alkene leads to an intermediate which forms epoxide either with a barrier on the low-spin surface or without a barrier after spin inversion. Supporting evidence for this intermediate was obtained by using vinylcyclopropane traps. The chromium...

  17. Discovery of the Cobalt Isotopes

    OpenAIRE

    Szymanski, T.; Thoennessen, M.

    2009-01-01

    Twenty-six cobalt isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  18. Cobalt: for strength and color

    Science.gov (United States)

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  19. Chromium(III) -- chromium(VI) interconversions in seawater

    NARCIS (Netherlands)

    Weijden, C.H. van der; Reith, M.

    1982-01-01

    The stable form of dissolved chromium in oxygenated seawater is Cr(VI). But Cr(III)-species are also present at an analytically significant level. It is shown that Cr(III) is oxidized only slowly by dissolved oxygen, and that manganese oxide is a strong catalyst for such oxidation. However, the low

  20. Environmental biochemistry of chromium.

    Science.gov (United States)

    Losi, M E; Amrhein, C; Frankenberger, W T

    1994-01-01

    Chromium is a d-block transitional element with many industrial uses. It occurs naturally in various crustal materials and is discharged to the environment as industrial waste. Although it can occur in a number of oxidation states, only 3+ and 6+ are found in environmental systems. The environmental behavior of Cr is largely a function of its oxidation state. Hexavalent Cr compounds (mainly chromates and dichromates) are considered toxic to a variety of terrestrial and aquatic organisms and are mobile in soil/water systems, much more so than trivalent Cr compounds. This is largely because of differing chemical properties: Hexavalent Cr compounds are strong oxidizers and highly soluble, while trivalent Cr compounds tend to form relatively inert precipitates at near-neutral pH. The trivalent state is generally considered to be the stable form in equilibrium with most soil/water systems. A diagram of the Cr cycle in soils and water is given in Fig. 6 (Bartlett 1991). This illustration provides a summary of environmentally relevant reactions. Beginning with hexavalent Cr that is released into the environment as industrial waste, there are a number of possible fates, including pollution of soil and surface water and leaching into groundwater, where it may remain stable and, in turn, can be taken up by plants or animals, and adsorption/precipitation, involving soil colloids and/or organic matter. Herein lies much of the environmental concern associated with the hexavalent form. A portion of the Cr(VI) will be reduced to the trivalent form by inorganic electron donors, such as Fe2+ and S2-, or by bioprocesses involving organic matter. Following this conversion, Cr3+ can be expected to precipitate as oxides and hydroxides or to form complexes with numerous ligands. This fraction includes a vast majority of global Cr reserves. Soluble Cr3+ complexes, such as those formed with citrate, can undergo oxidation when they come in contact with manganese dioxide, thus reforming

  1. COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

    Directory of Open Access Journals (Sweden)

    Liudmila V. Dyakova

    2010-06-01

    Full Text Available The paper deals with the extracting cobalt salts by using mixtures on the basis of tertiary amine from multicomponent solutions from the process of hydrochloride leaching of cobalt concentrate. The optimal composition for the extraction mixture, the relationship between the cobalt distribution coefficients and modifier’s nature and concentration, and the saltingout agent type have been determined. A hydrochloride extraction technology of cobalt concentrate yielding a purified concentrated cobalt solution for the production of pure cobalt salts has been developed and introduced at Severonikel combine.

  2. Palladium-based Membrane Applications for Hydrogen Purification

    Institute of Scientific and Technical Information of China (English)

    LI Yin'e; MA Guang; JIA Zhihua; JIANG Ting

    2012-01-01

    It describes the purification of hydrogen isotopes,separation with the preparation of palladium-based membrane's technology,types,application,advantages and disadvantages of palladium in this article.Due to excellent comprehensive properties palladium composite membrane will become the future direction of development.At the same time it will develop preparation methods of the membrane support body with high mechanical strength and heat resistance and low-cost and palladium-based membrane.Also it will explore high service life and high transmittance of novel composite membrane.

  3. The use of trivalent chromium bath to obtain a solar selective black chromium coating

    Science.gov (United States)

    Survilienė, S.; Češūnienė, A.; Juškėnas, R.; Selskienė, A.; Bučinskienė, D.; Kalinauskas, P.; Juškevičius, K.; Jurevičiūtė, I.

    2014-06-01

    Black chromium coatings were electrodeposited from a trivalent chromium bath using a ZnO additive as a second main component. Black chromium was electrodeposited on steel and copper plates and substrates plated with bright nickel prior to black chromium electrodeposition. The black chromium coatings were characterized by XRD and SEM. The XRD data suggest that the phase structure of black chromium may be defined as a zinc solid solution in chromium or a chromium solid solution in zinc depending on the chromium/zinc ratio in the deposit. The role of substrate finish was evaluated through the corrosion resistance and reflectance of black chromium. According to corrosion tests the samples plated with bright nickel prior to black chromium deposition have shown the highest corrosion resistance. The electrodeposited black chromium possesses good optical properties for the absorption of solar energy. The absorption coefficient of black chromium was found to be over 0.99 for the samples obtained without the Ni undercoat and below 0.99 for those obtained with the use of Ni undercoat. However, the use of nickel undercoat before black chromium plating is recommended because it remarkably improves the corrosion resistance of samples.

  4. Electron transfer reactions of macrocyclic compounds of cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Heckman, R.A.

    1978-08-01

    The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

  5. Electrical conductivity and phase diagram of binary alloys. 21: The system palladium-chromium

    Science.gov (United States)

    Grube, G.; Knabe, R.

    1985-01-01

    Pd-Cr alloys were investigated by thermal analysis, hardness measurements, X-ray analysis, microscopic examination of etched pieces, and temperature-resistance curves of the solid alloys. Only one compound, Pd2Cr3, m, 1389 deg, is formed. It possesses a cubic face centered lattice and forms with excess Pd a series of solid solutions with a minimum m.p. at 45 atoms% Pd. Hardness maximum appears at the Pd2Cr3 point. Pd2Cr3 forms no solid solutions with Cr but eutectic point appears at 25 atoms% Pd, m. 1320 deg. The sp. resistance of pure Cr in an atom of H, indicates no allotropic forms. Cr2O3 is solid in molten Cr. Pure Cr melts at 1890 plus or minus 10 deg but Cr contg. Cr2O3 starts to melt at 1770 to 1790 deg.

  6. AN ELECTROPLATING METHOD OF FORMING PLATINGS OF NICKEL, COBALT, NICKEL ALLOYS OR COBALT ALLOYS

    DEFF Research Database (Denmark)

    1997-01-01

    An electroplating method of forming platings of nickel, cobalt, nickel alloys or cobalt alloys with reduced stresses in an electrodepositing bath of the type: Watt's bath, chloride bath or a combination thereof, by employing pulse plating with periodic reverse pulse and a sulfonated naphthalene...... additive. This method makes it possible to deposit nickel, cobalt, nickel or cobalt platings without internal stresses....

  7. Heat-Resistance of the Powder Cobalt Alloys Reinforced by Niobium or Titanium Carbide

    Directory of Open Access Journals (Sweden)

    Cherepova, T.S.

    2016-01-01

    Full Text Available The characteristics of heat-resistance of powder cobalt alloys at 1100 °C were investigated. These alloys were developed for the protection of workers banding shelves GTE blades from wear. The alloys were prepared by hot pressing powders of cobalt, chromium, aluminum, iron and niobium or titanium carbides. The values of heat resistance alloys containing carbides between 30 and 70% (vol. depend on the type made of carbide alloys: alloys with titanium carbide superior in heat-resistant alloy of niobium carbide. The most significant factor affecting on the heat-resistant alloys, is porosity: with its increase the parameters decline regardless of the type and content of carbide. The optimum composition of powder heat resisting alloys of titanium carbide with a melting point above 1300 °C were determined for use in the aircraft engine.

  8. Functionalized Palladium Nanoparticles for Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    H. Baccar

    2011-01-01

    Full Text Available We present a comparison between two biosensors for hydrogen peroxide (H2O2 detection. The first biosensor was developed by the immobilization of Horseradish Peroxidase (HRP enzyme on thiol-modified gold electrode. The second biosensor was developed by the immobilization of cysteamine functionalizing palladium nanoparticles on modified gold surface. The amino groups can be activated with glutaraldehyde for horseradish peroxidase immobilization. The detection of hydrogen peroxide was successfully observed in PBS for both biosensors using the cyclic voltammetry and the chronoamperometry techniques. The results show that the limit detection depends on the large surface-to-volume ratio attained with palladium nanoparticles. The second biosensor presents a better detection limit of 7.5 μM in comparison with the first one which is equal to 75 μM.

  9. Hydrogen in magnesium palladium thin layer structures

    OpenAIRE

    Kruijtzer, G. L.

    2008-01-01

    In this thesis, the study of hydrogen storage, absorption and desorption in magnesium layers is described. The magnesium layers have a thickness of 50-500 nm and are covered by a palladium layer which acts as a hydrogen dissociation/association catalyst. The study was preformed under ultra high vacuum conditions to avoid oxygen contamination. The main analysis techniques were RBS, ERD and TDS.

  10. Sample Characterization of Palladium Supported on Tetraphenylborate

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, M.J.

    2001-04-04

    The primary objective of this research was to use XAFS spectroscopic techniques such as SANES and EXAFS to obtain information on Pd and Hg in samples that were potentially supported on KTPB and had been reacted with dissolved TPB and TPB decomposition products. This work was performed in support of the Small Tank Tetraphenylborate Salt Disposition Alternative program seeking to better understand the mechanism of palladium catalyzed tetraphenylborate decomposition.

  11. Palladium-Catalyzed, Enantioselective Heine Reaction.

    Science.gov (United States)

    Punk, Molly; Merkley, Charlotte; Kennedy, Katlyn; Morgan, Jeremy B

    2016-07-01

    Aziridines are important synthetic intermediates for the generation of nitrogen-containing molecules. N-Acylaziridines undergo rearrangement by ring expansion to produce oxazolines, a process known as the Heine reaction. The first catalytic, enantioselective Heine reaction is reported for meso-N-acylaziridines where a palladium(II)-diphosphine complex is employed. The highly enantioenriched oxazoline products are valuable organic synthons and potential ligands for transition-metal catalysis.

  12. Palladium-catalysed ortho arylation of acetanilides

    Indian Academy of Sciences (India)

    Guo-zhen zhang; Cheng-Qun Chen; Xin-Hua Feng; Guo-Sheng Huang

    2010-03-01

    The palladium-catalysed direct arylation of acetanilides by using C-H activation methodology has been demonstrated. Several acetanilides were coupled with aryl iodides in the presence of 10 mol% of Pd(OAc)2, 1.0 equiv of Cu(OTf)2, and 0.6 equiv of Ag2O to afford the corresponding products in moderate to excellent yields. The results showed that the amount of Ag2O was important for this protocol.

  13. Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS.

    Science.gov (United States)

    Lameiras, J; Soares, M E; Bastos, M L; Ferreira, M

    1998-10-01

    Procedures for the quantification of total chromium and hexavalent chromium in UHT milk samples are presented. Total chromium was determined directly in milk with the addition of a surfactant and a mixture of Pd and Mg as a chemical modifier. For the selective separation of hexavalent chromium, the sample pre-treatment consisted in precipitation of proteins and elution of the supernatant through a Chromabond NH2 column. The metal was eluted with nitric acid. Both total chromium and hexavalent chromium were evaluated by atomic absorption spectrometry with electrothermal atomization using the same instrumental conditions. The detection limits were 0.2 and 0.15 microgram l-1 for total chromium and hexavalent chromium, respectively. The linearity ranges under the optimized conditions were 0.2-20 and 0.15-50 micrograms l-1. For total chromium the precision was 4.9 and 5.7% for the analytical and the over-all procedure, respectively, and for hexavalent chromium 4.3 and 4.9%, respectively. The validation of both procedures was performed by the standard additions method and the recoveries were higher than 93% in all cases. For total chromium, a certified reference material was also used to validate the methodology. The methods were applied to the determination of total chromium and hexavalent chromium in 60 UHT milk samples.

  14. COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

    OpenAIRE

    Liudmila V. Dyakova; Aleksander G. Kasikov; Elena S. Kshumaneva; Svetlana V. Drogobuzhskaya

    2010-01-01

    The paper deals with the extracting cobalt salts by using mixtures on the basis of tertiary amine from multicomponent solutions from the process of hydrochloride leaching of cobalt concentrate. The optimal composition for the extraction mixture, the relationship between the cobalt distribution coefficients and modifier’s nature and concentration, and the saltingout agent type have been determined. A hydrochloride extraction technology of cobalt concentrate yielding a purified concentrated cob...

  15. Extracellular Palladium Nanoparticle Production using Geobacter sulfurreducens

    KAUST Repository

    Yates, Matthew D.

    2013-09-03

    Sustainable methods are needed to recycle precious metals and synthesize catalytic nanoparticles. Palladium nanoparticles can be produced via microbial reduction of soluble Pd(II) to Pd(0), but in previous tests using dissimilatory metal reducing bacteria (DMRB), the nanoparticles were closely associated with the cells, occupying potential reductive sites and eliminating the potential for cell reuse. The DMRB Geobacter sulfurreducens was shown here to reduce soluble Pd(II) to Pd(0) nanoparticles primarily outside the cell, reducing the toxicity of metal ions, and allowing nanoparticle recovery without cell destruction that has previously been observed using other microorganisms. Cultures reduced 50 ± 3 mg/L Pd(II) with 1% hydrogen gas (v/v headspace) in 6 h incubation tests [100 mg/L Pd(II) initially], compared to 8 ± 3 mg/L (10 mM acetate) without H2. Acetate was ineffective as an electron donor for palladium removal in the presence or absence of fumarate as an electron acceptor. TEM imaging verified that Pd(0) nanoparticles were predominantly in the EPS surrounding cells in H2-fed cultures, with only a small number of particles visible inside the cell. Separation of the cells and EPS by centrifugation allowed reuse of the cell suspensions and effective nanoparticle recovery. These results demonstrate effective palladium recovery and nanoparticle production using G. sulfurreducens cell suspensions and renewable substrates such as H2 gas. © 2013 American Chemical Society.

  16. Platinum- and platinum alloy-coated palladium and palladium alloy particles and uses thereof

    Science.gov (United States)

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir Branko

    2010-04-06

    The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

  17. Transport of cobalt-60 industrial radiation sources

    Science.gov (United States)

    Kunstadt, Peter; Gibson, Wayne

    This paper will deal with safety aspects of the handling of Cobalt-60, the most widely used industrial radio-isotope. Cobalt-60 is a man-made radioisotope of Cobalt-59, a naturally occurring non radioactive element, that is made to order for radiation therapy and a wide range of industrial processing applications including sterilization of medical disposables, food irradiation, etc.

  18. Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jøns, O; Nielsen, B

    1992-01-01

    A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both...

  19. Effect of Palladium Form on Tetraphenylborate Decomposition Rate

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.D. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1998-04-28

    Palladium catalyzes the decomposition of tetraphenylborate in alkaline solutions. Researchers postulate several decomposition mechanisms that differ in the form of the palladium catalyst. Potential forms include solid and soluble, different soluble species (such as aqueous or organic soluble), and different oxidation states (i.e., 0, II, and IV). Initial tests measured the reactivity and distribution of four Pd forms in tetraphenylborate slurries.

  20. Sonoassisted microbial reduction of chromium.

    Science.gov (United States)

    Kathiravan, Mathur Nadarajan; Karthick, Ramalingam; Muthu, Naggapan; Muthukumar, Karuppan; Velan, Manickam

    2010-04-01

    This study presents sonoassisted microbial reduction of hexavalent chromium (Cr(VI)) using Bacillus sp. isolated from tannery effluent contaminated site. The experiments were carried out with free cells in the presence and absence of ultrasound. The optimum pH and temperature for the reduction of Cr(VI) by Bacillus sp. were found to be 7.0 and 37 degrees C, respectively. The Cr(VI) reduction was significantly influenced by the electron donors and among the various electron donors studied, glucose offered maximum reduction. The ultrasound-irradiated reduction of Cr(VI) with Bacillus sp. showed efficient Cr(VI) reduction. The percent reduction was found to increase with an increase in biomass concentration and decrease with an increase in initial concentration. The changes in the functional groups of Bacillus sp., before and after chromium reduction were observed with FTIR spectra. Microbial growth was described with Monod and Andrews model and best fit was observed with Andrews model.

  1. Controlling the misuse of cobalt in horses.

    Science.gov (United States)

    Ho, Emmie N M; Chan, George H M; Wan, Terence S M; Curl, Peter; Riggs, Christopher M; Hurley, Michael J; Sykes, David

    2015-01-01

    Cobalt is a well-established inducer of hypoxia-like responses, which can cause gene modulation at the hypoxia inducible factor pathway to induce erythropoietin transcription. Cobalt salts are orally active, inexpensive, and easily accessible. It is an attractive blood doping agent for enhancing aerobic performance. Indeed, recent intelligence and investigations have confirmed cobalt was being abused in equine sports. In this paper, population surveys of total cobalt in raceday samples were conducted using inductively coupled plasma mass spectrometry (ICP-MS). Urinary threshold of 75 ng/mL and plasma threshold of 2 ng/mL could be proposed for the control of cobalt misuse in raceday or in-competition samples. Results from administration trials with cobalt-containing supplements showed that common supplements could elevate urinary and plasma cobalt levels above the proposed thresholds within 24 h of administration. It would therefore be necessary to ban the use of cobalt-containing supplements on raceday as well as on the day before racing in order to implement and enforce the proposed thresholds. Since the abuse with huge quantities of cobalt salts can be done during training while the use of legitimate cobalt-containing supplements are also allowed, different urinary and plasma cobalt thresholds would be required to control cobalt abuse in non-raceday or out-of-competition samples. This could be achieved by setting the thresholds above the maximum urinary and plasma cobalt concentrations observed or anticipated from the normal use of legitimate cobalt-containing supplements. Urinary threshold of 2000 ng/mL and plasma threshold of 10 ng/mL were thus proposed for the control of cobalt abuse in non-raceday or out-of-competition samples. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  3. Determination of the stability constants for cobalt, nickel and palladium homogeneous catalyst complexes containing triphenylphosphine ligands

    NARCIS (Netherlands)

    Djekic, T.; Zivkovic, Z.; van der Ham, A.G.J.; de Haan, A.B.

    2006-01-01

    Homogeneous catalysts are complex compounds that are always in equilibrium with their free metal, free ligand and other forms of complexes. The ratios between different species are defined by the stability constants, which are influenced by different parameters such as the type of metal, ligand, cou

  4. Functionalizing Titanium Disilicide Nanonets with Cobalt Oxide and Palladium for Stable Li Oxygen Battery Operations.

    Science.gov (United States)

    Yao, Xiahui; Cheng, Qingmei; Xie, Jin; Dong, Qi; Wang, Dunwei

    2015-10-07

    Li oxygen (Li-O2) batteries promise high energy densities but suffer from challenges such as poor cycling lifetime and low round-trip efficiencies. Recently, the instability of carbon cathode support has been recognized to contribute significantly to the problems faced by Li-O2 batteries. One strategy to address the challenge is to replace carbon materials with carbon-free ones. Here, we present titanium silicide nanonets (TiSi2) as such a new material platform for this purpose. Because TiSi2 exhibits no oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) activities, catalysts are required to promote discharge and recharge reactions at reduced overpotentials. Pd nanoparticles grown by atomic layer deposition (ALD) were observed to provide the bifunctionalities of ORR and OER. Their adhesion to TiSi2 nanonets, however, was found to be poor, leading to drastic performance decay due to Pd detachments and aggregation. The problem was solved by adding another layer of Co3O4, also prepared by ALD. Together, the Pd/Co3O4/TiSi2 combination affords the desired functionalities and stability. Li-O2 test cells that lasted more than 126 cycles were achieved. The reversible formation and decomposition of Li2O2 was verified by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), ferrocenium back-titration, and gas-chromatography and mass spectrometry (GC-MS). Our results provide a new material platform for detailed studies of Li-O2 operations for better understanding of the chemistries involved, which is expected to help pave the way toward practical Li-O2 battery realizations.

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

    Science.gov (United States)

    Thomas, Nicholas C.; And Others

    1989-01-01

    Presents a laboratory experiment which illustrates the formation of tris(phenanthroline)cobalt complexes in the 2+ and 3+ oxidation states, the effect of coordination on reactions of the ligand, and the use of a ligand displacement reaction in recovering the transformed ligand. Uses IR, UV-VIS, conductivity, and NMR. (MVL)

  6. Pharmacokinetics and dosimetry of cobalt-55 and cobalt-57

    NARCIS (Netherlands)

    Jansen, HML; Knollema, S; vanderDuin, LV; Willemsen, ATM; Wiersma, A; Franssen, EJF; Russel, FGM; Korf, J; Paans, AMJ

    1996-01-01

    The isotopes Co-55 and Co-57 have been evaluated for PET and SPECT imaging in several clinical brain studies. For clinical application of cobalt, it is important to know the delivered radiation dose. The biodistribution of Co-55 in both rat and humans after intravenous (bolus)-administration was

  7. Palladium-based dental alloys are associated with oral disease and palladium-induced immune responses

    NARCIS (Netherlands)

    Muris, J.; Scheper, R.J.; Kleverlaan, C.J.; Rustemeyer, T.; van Hoogstraten, I.M.W.; von Blomberg, M.E.; Feilzer, A.J.

    2014-01-01

    Background Palladium (Pd) and gold (Au) based dental alloys have been associated with oral disease. Objectives This study was designed to explore possible associations between the presence of Au-based and Pd-based dental alloys, and oral lesions, systemic complaints, and specific in vivo and in vitr

  8. Characterization of feline serum-cobalt binding.

    Science.gov (United States)

    Schnelle, Amy N; Barger, Anne M; MacNeill, Amy L; Mitchell, Mark M; Solter, Philip

    2015-06-01

    Oxidative stress inhibits albumin's ability to complex with cobalt. Feline serum-cobalt binding has not been described. The objective was to develop a cobalt binding test for use with feline serum, and correlate the results with other biochemical and cellular constituents in blood, and with clinical diseases of cats. A colorimetric test of cobalt binding, based on the oxidation-reduction reaction of Co(+2) and dithiothreitol, was developed using feline serum. The test was used to measure cobalt binding in stored serum from 176 cats presented to the University of Illinois Veterinary Teaching Hospital for a variety of disease conditions. Time-matched hematology and biochemical data, and clinical information, were obtained from the medical record of each cat and correlated with the serum-cobalt binding results. Serial dilution of feline serum with phosphate-buffered saline resulted in a highly linear decrease in serum-cobalt binding (r(2)  = .9984). Serum-cobalt binding of the clinical samples also correlated with albumin concentrations in a stepwise linear regression model (r(2)  = .425), and both cobalt binding and albumin were significantly decreased in cases of inflammation. Albumin and cobalt binding also shared significant correlations with several erythron variables, and serum concentration of total calcium and bilirubin. The correlation of cobalt binding measured by a colorimetric test with albumin concentration in the clinical samples and with serum dilution is consistent with feline albumin-cobalt complex formation. Hypoalbuminemia is the likely cause of reduced serum-cobalt binding in inflammation and the correlations observed between cobalt binding and other variables. © 2015 American Society for Veterinary Clinical Pathology.

  9. Electrodeposition of chromium from trivalent chromium urea bath containing sulfate and chloride

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The reduction of Cr( Ⅲ) to Cr( Ⅱ ) on copper electrode in trivalent chromium urea bath containing chromium sulfate and chromium chloride as chromium source has been investigated by potentiodynamic sweep. The transfer coefficient α for reduction of Cr( Ⅲ ) to Cr( Ⅱ ) on copper electrode was calculated as 0.46. The reduction is a quasi-reversible process. J-t responses at different potential steps showed that the generation and adsorption characteristics of carboxylate bridged oligomer are relevant to cathode potential. The interface behavior between electrode and solution for Cr( Ⅲ ) complex is a critical factor influencing sustained electrode position of chromium. The hypotheses of the electro-inducing polymerization of Cr( Ⅲ ) was proposed. The potential scope in which sustained chromium deposits can be prepared is from- 1.3 V to- 1.7 V (vs SCE) in the urea bath. Bright chromium deposits with thickness of 30 μm can be prepared in the bath.

  10. Clinical utility of platinum chromium bare-metal stents in coronary heart disease

    Directory of Open Access Journals (Sweden)

    Jorge C

    2015-08-01

    Full Text Available Claudia Jorge,1 Christophe Dubois1,2 1Department of Cardiovascular Medicine, University Hospitals Leuven, 2Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium Abstract: Coronary stents represent a key development for the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. While drug-eluting stents gained wide acceptance in contemporary percutaneous coronary intervention practice, further developments in bare-metal stents remain crucial for patients who are not candidates for drug-eluting stents, or to improve metallic platforms for drug elution. Initially, stent platforms used biologically inert stainless steel, restricting stent performance due to limitations in flexibility and strut thickness. Later, cobalt chromium stent alloys outperformed steel as the material of choice for stents, allowing latest generation stents to be designed with significantly thinner struts, while maintaining corrosion resistance and radial strength. Most recently, the introduction of the platinum chromium alloy refined stent architecture with thin struts, high radial strength, conformability, and improved radiopacity. This review will provide an overview of the novel platinum chromium bare-metal stent platforms available for coronary intervention. Mechanical properties, clinical utility, and device limitations will be summarized and put into perspective. Keywords: bare metal stent, coronary stent alloys, coronary artery disease

  11. Characterisation of interfaces in nanocrystalline palladium

    Indian Academy of Sciences (India)

    R Divakar; V S Raghunathan

    2003-02-01

    Structures of grain boundaries and triple line junctions in nanocrystalline materials are of interest owing to large fractions of atoms in nanocrystalline materials being at these interfacial positions. Grain boundary and triple line junction structures in nanocrystalline palladium have been studied using high-resolution transmission electron microscopy (HRTEM). The main microstructural features observed include the varying atomic structures of grain boundaries and the presence of disordered regions at triple line junctions. Also, there is variation in lattice parameters in different nanocrystalline grains. Geometric phase analysis is used to quantify atomic displacements within nanocrystalline grains. Displacement fields thus detected indicate links to the interface structures.

  12. Palladium-catalyzed asymmetric quaternary stereocenter formation.

    Science.gov (United States)

    Gottumukkala, Aditya L; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G; Minnaard, Adriaan J

    2012-05-29

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl(2), PhBOX, and AgSbF(6), and provides products in up to 99% enantiomeric excess, with good yields. Based on this strategy, (-)-α-cuparenone has been prepared in only two steps. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

    Science.gov (United States)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil; Lidén, Carola; Julander, Anneli; Møller, Per; Johansen, Jeanne Duus

    2010-08-01

    Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure. The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. The cobalt spot test was used to assess cobalt release from all items. Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin-cobalt plating on these. This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future. Industries may not be fully aware of the potential cobalt allergy problem.

  14. 29 CFR 1915.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... system dysfunction; any history of asthma, dermatitis, skin ulceration, or nasal septum perforation; and... is present or is likely to be present from skin or eye contact with chromium (VI), the employer shall... cleaned in a manner that minimizes skin or eye contact with chromium (VI) and effectively prevents...

  15. 29 CFR 1926.1126 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... system dysfunction; any history of asthma, dermatitis, skin ulceration, or nasal septum perforation; and... is present or is likely to be present from skin or eye contact with chromium (VI), the employer shall... cleaned in a manner that minimizes skin or eye contact with chromium (VI) and effectively prevents...

  16. Chromium Contamination in Army Face Masks.

    Science.gov (United States)

    1989-01-01

    containing carbon particles by inhalation when wearing face masks. Other potential health effects are chrome allergies and nonneoplastic lesions of...chronic inflammation—have been reported in chrome -platers and other workers exposed to aerosols of chromium (VI) compounds. Chronic pharyngitis...monochromates and dichromates of sodium, potassium , ammonium, lithium, cesium, and rubidium. ACGIH includes chromium in its list of known human

  17. Cobalt toxicity in anaerobic granular sludge: influence of chemical speciation

    NARCIS (Netherlands)

    Bartacek, J.; Fermoso, F.G.; Baldo-Urrutia, A.M.; Hullebusch, van E.D.; Lens, P.N.L.

    2008-01-01

    The influence of cobalt speciation on the toxicity of cobalt to methylotrophic methanogenesis in anaerobic granular sludge was investigated. The cobalt speciation was studied with three different media that contained varying concentrations of complexing ligands [carbonates, phosphates and ethylenedi

  18. Cobalt toxicity in anaerobic granular sludge: influence of chemical speciation

    NARCIS (Netherlands)

    Bartacek, J.; Fermoso, F.G.; Baldo-Urrutia, A.M.; Hullebusch, van E.D.; Lens, P.N.L.

    2008-01-01

    The influence of cobalt speciation on the toxicity of cobalt to methylotrophic methanogenesis in anaerobic granular sludge was investigated. The cobalt speciation was studied with three different media that contained varying concentrations of complexing ligands [carbonates, phosphates and

  19. Cobalt toxicity in anaerobic granular sludge: influence of chemical speciation

    NARCIS (Netherlands)

    Bartacek, J.; Fermoso, F.G.; Baldo-Urrutia, A.M.; Hullebusch, van E.D.; Lens, P.N.L.

    2008-01-01

    The influence of cobalt speciation on the toxicity of cobalt to methylotrophic methanogenesis in anaerobic granular sludge was investigated. The cobalt speciation was studied with three different media that contained varying concentrations of complexing ligands [carbonates, phosphates and ethylenedi

  20. [Bioremediation of chromium (VI) contaminated site by reduction and microbial stabilization of chromium].

    Science.gov (United States)

    Zheng, Jia-Chuan; Zhang, Jian-Rong; Liu, Xi-Wen; Xu, Qian; Shi, Wei-Lin

    2014-10-01

    Chromium (VI) contaminated soil samples were collected from a chemical plant in Suzhou. Firstly, the reduced soil was prepared by adding reagent (Stone-sulfure reagent) into polluted soil to transfer most chromium (VI) into chromium (III), then a nutrient solution was introduced into the reduced soil, and the stabilized soil was obtained after 60 days culturing. The chromium (VI) content of the three kinds of soil was analyzed. The results showed that the chromium (VI) content in toxicity characteristic leaching liquid (TCLL) dropped by 96. 8% (from 8.26 mg · L(-1) to 0.26 mg · L(-1)), and the total chromium content dropped by 95.7% (from 14.66 mg · L(-1) to 0.63 mg · L(-1)) after bioremediation in 5% nutrient solution. Additionally, the durability of chromium stabilization was tested by potassium permanganate oxidation and sterilization of microbe-treated soil. After oxidation, the chromium (VI) content in TCLL of the reduced soil was increased from 8.26 mg · L(-1) to 14.68 mg · L(-1). However, the content after bioremediation was decreased to 2.68 mg · L(-1). The results of sterilization demonstrated that the death of microbe had no significant effect on the stabilization of chromium. Consequently, the research in this paper demonstrated the feasibility of bioremediation of chromium (VI) polluted soil through reduction followed by stabilization/soilidification, and provided a technique with low cost but high efficiency.

  1. Hydrogen Adsorption onto Magnesium Palladium and Magnesium Palladium Niobium Multilayer Thin Films

    Science.gov (United States)

    Steinmetz, Christian; Hettinger, Jeffrey; Dobbins, Tabbetha

    2013-03-01

    We report on the synthesis and characterization of magnesium palladium and magnesium niobium multilayer thin films as a possible reversible hydrogen storage material. The multilayer thin films are characterized by x-ray diffraction (XRD) and x-ray reflectivity (XRR) before and after hydrogen uptake. This study examines the optimal thickness of the magnesium film which would allow the diffusion of hydrogen to form magnesium hydride (MgH2). Thin barriers of palladium and niobium permit hydrogen to permeate while acting as a diffusion barrier to oxygen. Multilayer thin films are grown with various magnesium thicknesses via magnetron sputtering on a sapphire substrate. Thicknesses of Mg, MgH2, Pd, and Nb are reported. Likewise, interfacial roughness attributable to hydrogenation and dehydrogenation cycling measured using XRR are reported.

  2. Cobalt release from implants and consumer items and characteristics of cobalt sensitized patients with dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Menne, Torkil; Liden, Carola

    2012-01-01

    -containing dental alloys and revised hip implant components.Results. Six of eight dental alloys and 10 of 98 revised hip implant components released cobalt in the cobalt spot test, whereas none of 50 mobile phones gave positive reactions. The clinical relevance of positive cobalt test reactions was difficult...

  3. Hot Corrosion of Cobalt-Base Alloys

    Science.gov (United States)

    1975-06-01

    scale is similar to that which has already been proposed for cobalt . The oxide ions would react with the Al203 to form aluminate ions in the Na2S04...resistance of cobalt -base and nickel-base alloys. The contract was accomplished under the technical direction of Dr. H. C. Graham of the Aerospace Research...Oxidized Specimens RESULTS AND DISCUSSION 1. INTRODUCfiON 2. SODIUM SULFATE INDUCED HOT CORROSION OF COBALT a. Introduction b. Experimental c

  4. Cobalt-Base Alloy Gun Barrel Study

    Science.gov (United States)

    2014-07-01

    are presented in Section 5. 2. Materials and methods The composition of the cobalt -base alloy (CBA) is presented in Table 1. The production of this... Cobalt -Base Alloy Gun Barrel Study by William S. de Rosset and Jonathan S. Montgomery ARL-RP-0491 July 2014 A reprint...21005-5069 ARL-RP-0491 July 2014 Cobalt -Base Alloy Gun Barrel Study William S. de Rosset and Jonathan S. Montgomery Weapons and Materials

  5. Mineral resource of the month: cobalt

    Science.gov (United States)

    Shedd, Kim B.

    2009-01-01

    Cobalt is a metal used in numerous commercial, industrial and military applications. On a global basis, the leading use of cobalt is in rechargeable lithium-ion, nickel-cadmium and nickel-metal hydride battery electrodes. Cobalt use has grown rapidly since the early 1990s, with the development of new battery technologies and an increase in demand for portable electronics such as cell phones, laptop computers and cordless power tools.

  6. Effect of palladium on sulfide tarnishing of noble metal alloys.

    Science.gov (United States)

    Suoninen, E; Herø, H; Minni, E

    1985-10-01

    Electron spectroscopic studies of Au-Ag-Cu alloys of the type used for dental castings show that small additions (less than or equal to 3 wt%) of palladium reduce essentially the thickness of the sulfide layer formed on surfaces of samples treated in aqueous Na2S solutions. Relative to silver, palladium does not enrich in the sulfide, but statistically significant enrichment is found immediately below the sulfide layer. This enrichment probably takes place during the exposure of the substrate surface to atmosphere before the sulfiding treatment. The mechanism of the impeding effect of palladium on sulfiding is assumed to be a decrease in diffusion from the bulk alloy to the surface due to the enriched layer. The effect cannot be explained by changes in the electronic structure of the alloy due to palladium alloying.

  7. solid phase extraction of trace amounts of palladium ions using ...

    African Journals Online (AJOL)

    Preferred Customer

    hydroxybenzylidene)- ... applied to the determination of palladium ion in environmental samples. KEY WORDS: ... preparation tool and provides a method that is simple and safe to use. .... and recovery of ions was investigated under optimum conditions.

  8. A New Palladium-Catalyzed Phenyl-Alkene Bond Formation

    Directory of Open Access Journals (Sweden)

    René Roy

    2002-05-01

    Full Text Available A new method of palladium-catalyzed phenyl-alkene bond formation is reported. This reaction involves transfer of all three phenyl groups from triphenylantimony onto alkenes containing allylic protons.

  9. Highly efficient palladium-catalyzed hydrostannation of ethyl ethynyl ether.

    Science.gov (United States)

    Andrews, Ian P; Kwon, Ohyun

    2008-12-08

    The palladium-catalyzed hydrostannation of acetylenes is widely exploited in organic synthesis as a means of forming vinyl stannanes for use in palladium-catalyzed cross-coupling reactions. Application of this methodology to ethyl ethynyl ether results in an enol ether that is challenging to isolate from the crude reaction mixture because of incompatibility with typical silica gel chromatography. Reported here is a highly efficient procedure for the palladium-catalyzed hydrostannation of ethyl ethynyl ether using 0.1% palladium(0) catalyst and 1.0 equiv of tributyltin hydride. The product obtained is a mixture of regioisomers that can be carried forward with exclusive reaction of the beta-isomer. This method is highly reproducible; relative to previously reported procedures, it is more economical and involves a more facile purification procedure.

  10. Biological synthesis of cobalt ferrite nanoparticles

    Directory of Open Access Journals (Sweden)

    Anal K. Jha

    2012-01-01

    Full Text Available A low-cost green and reproducible yeast (Saccharomyces cerevisiae mediated biosynthesis of cobalt ferrite nanoparticles is reported. The synthesis is performed at close to room temperature in the laboratory. X-ray, Fourier transform infrared spectroscopy and high resolution transmission electron microscopy analyses are performed to ascertain the formation of cobalt ferrite nanoparticles. Individual nanoparticles, as well as a very few aggregate having the size of 3-15 nm, were found. The vibrating sample magnetometer measurement showed superparamagnetic behavior in cobalt ferrite nanoparticles. The mechanism involved in the biosynthesis of cobalt ferrite nanoparticles has also been discussed.

  11. Low-chromium reduced-activation chromium-tungsten steels

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.; Maziasz, P.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    Bainitic microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of non-classical bainite were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was found to be considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2 1/4Cr-2W and 2 1/4Cr-2WV steel compositions to increase their hardenability, and the microstructures and mechanical properties were examined.

  12. Cobalt serum levels differ in well functioning Birmingham resurfacing and Birmingham modular THA.

    Science.gov (United States)

    Renner, Lisa; Faschingbauer, Martin; Schmidt-Braekling, Tom; Boettner, Friedrich

    2016-05-01

    Metal-on-metal (MoM) bearings are known to release metal ions secondary to wear and corrosion. This may cause local reactions (adverse soft tissue reactions and osteolysis) and systemic effects. Little is known about the exact pattern and the differences between large head MoM total hip replacements (THA) and resurfacings (HR). (1) Is there a difference in metal ion concentrations between HR and MoM-THR using the same bearing design (Birmingham Hip Resurfacing System, Smith & Nephew, Inc. Memphis, TN, USA)? (2) Are metal ion levels changing over time in MoM-THA or HR? (3) Do acetabular inclination angle and femoral component size influence cobalt and chromium levels? Is there a correlation between clinical outcome and metal ion levels? A retrospective analysis was conducted in 77 well functioning unilateral Birmingham HR and 42 well functioning unilateral modular Birmingham MoM-THA (Smith & Nephew, Inc. Memphis, TN, USA) operated on between 2007 and 2012. Blood samples were taken at a minimum of 13 months and subsequent during annual follow-ups. (1) Cobalt levels were significantly higher in MoM-THA compared to HR (p Cobalt is increasing over time in MoM-THA (p = 0.030) whereas metal ions remain stable in HR. (3) Metal ion levels were not affected by acetabular inclination angle and femoral component size in MoM-THA. Chromium levels correlate with the femoral component size (r = -0.240; p = 0.037), the UCLA activity score (r = -0.344; p = 0.003) and the VAS (r = 0.263; p = 0.38) in HR. Considering that HR and MoM-THA used the same MoM bearing design, increased cobalt levels may be related to trunnion wear or corrosion. Elevated cobalt levels should raise concern for corrosion related failure in MoM-THA.

  13. Oxidation of low cobalt alloys

    Science.gov (United States)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  14. Study on Systemic Separation of Palladium, Silver, Cadmium and Tin

    Institute of Scientific and Technical Information of China (English)

    YU; Zhen-hua; HUANG; Kun

    2013-01-01

    To accurately measure the yields of palladium,silver,cadmium and tin that generated from the fission of plutonium,radiochemical method is needed because there is much interference in using directγ-spectroscopy measurements.Usually,we want to get as much as possible the experiment data from one target,so it is required systemic separation of palladium,silver,cadmium and tin.Considering the

  15. Neurotoxicity and Ototoxicity of Cobalt%钴的神经毒性及耳毒性

    Institute of Scientific and Technical Information of China (English)

    李鹏; 丁大连; 曾祥丽; Richard Salvi; Jerome A. Roth

    2015-01-01

    Cobalt is an important essential element that is required for the synthesis and functional activity of vitamin B12. Therefore, cobalt is necessary for life. However, if intracellular concentrations of cobalt are excessive due to occupation⁃al exposure, dietary intake, or endogenous exposure from cobalt-chromium implants, it can also lead to a severe disorder, called metallosis characterized by sensorineural hearing loss, nervous tinnitus, visual impairment, cognitive impairment, pe⁃ripheral neuropathy, cardiomyopathy, heart failure, thyroid problems, skin rashes, etc. Among these toxicities by cobalt, senso⁃ry deafness and optic atrophy are the most noticeable symptoms. The toxic mechanisms of cobalt mainly involve oxidative stress, hypoxic injury and mitochondrial-induced apoptosis. Therefore, animal models of cobalt intoxication are applicable to research examining an imbalance in oxidation/antioxidation equilibrium, intracellular hypoxia, and mitochondria initiated apoptotic pathways, especially in the auditory, vision and nervous systems.%钴是参与维生素B12合成和许多生命活动中必不可少的微量元素,然而一旦机体细胞内的钴离子含量因职业暴露或因饮食摄取钴过量或因钴合金人工假体内源性释放超过安全标准,则可导致严重的金属沉着疾病,这种金属沉着病的症状主要包括感音神经性耳聋、神经性耳鸣、视觉缺陷、认知缺陷、心肌病、心衰、甲状腺疾病、皮肤感觉异常等,在上述病症中,感音神经性耳聋和视神经萎缩是最明显的钴中毒症状。钴中毒引起的细胞损害机制主要涉及细胞的氧化应激和缺氧性损害以及线粒体损害引起的细胞凋亡。因此,钴中毒引起的细胞损害模型尤其适用于听觉系统和视觉系统以及神经系统中因细胞内氧化/抗氧化失衡和细胞缺氧以及线粒体凋亡通路等方面的医学实验研究。

  16. Synthesis of Chromium (Ⅲ) 5-aminosalicylate

    Institute of Scientific and Technical Information of China (English)

    LI Wei; HAO Er-jun; JIANG Yu-qin

    2004-01-01

    As we all known that diabetes is a chronic disease with major health consequences.Research has revealed that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF) [1], no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr) [2] . So there is potential for the design of new chromium drugs .5-Aminosalicylic acid (5-ASA) is identified as an active component in the therapy of inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis . The therapeutic action of 5-ASA is believed to be coupled to its ability to act as a free radical scavenger [3-4],acting locally on the inflamed colonic mucosa [5-7]. However, the clinical use of 5-ASA is limited, since orally administered 5-ASA is rapidly and completely absorbed from the upper gastrointestinal tract and therefore the local therapeutic effects of 5-ASA in the colon is hardly expected.In this paper, we report the synthesis of chromium(Ⅲ)5-aminosalicylate from 5-ASA and CrCl3. 6H2O.The synthesis route is as follow:The complex has been characterized by elemental analysis, IR spectra, X-ray powder diffractionand TG-DTA . They indicate that the structure is tris(5-ASA) Chromium . Experiments show that thecomplex has a good activity for supplement tiny dietary chromium, lowering blood glucose levels,lowering serum lipid levels and in creasing lean body mass .

  17. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    Directory of Open Access Journals (Sweden)

    Anđelković Darko H.

    2012-01-01

    Full Text Available Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III and chromium(VI were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values.

  18. Characteristics of chromium-allergic dermatitis patients prior to regulatory intervention for chromium in leather

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus;

    2014-01-01

    BACKGROUND: Chromium-tanned leather articles currently constitute the most important cause of contact allergy to chromium in Denmark. A regulation on the content of hexavalent chromium in leather was adopted in November 2013 by the EU member states. OBJECTIVES: To characterize patients...... with chromium allergy and their disease, to serve as a baseline for future studies on the potential effect of the new regulation on chromium in leather. METHODS: A questionnaire case-control study was performed on 155 dermatitis patients with positive patch test reactions to potassium dichromate and a matched...... control group of 621 dermatitis patients. Comparisons were made by use of a χ(2) -test and the Mann-Whitney U-test. Logistic regression analyses were used to test for associations. RESULTS: Sixty-six per cent of chromium-allergic patients had a positive history of contact dermatitis caused by leather...

  19. Chromium in leather footwear-risk assessment of chromium allergy and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Strandesen, Maria; Poulsen, Pia B;

    2012-01-01

    Background. Chromium-tanned leather footwear, which releases >3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis. Objectives. To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact...... allergy and dermatitis. Methods. Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr......(VI) was 3 ppm. Results. Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0...

  20. Electrocatalysts having platium monolayers on palladium, palladium alloy, and gold alloy core-shell nanoparticles, and uses thereof

    Energy Technology Data Exchange (ETDEWEB)

    Adzic, Radoslav (Setauket, NY); Mo, Yibo (Naperville, IL); Vukmirovic, Miomir (Port Jefferson Station, NY); Zhang, Junliang (Rochester, NY)

    2010-12-21

    The invention relates to platinum-coated particles useful as fuel cell electrocatalysts. The particles are composed of a noble metal or metal alloy core at least partially encapsulated by an atomically thin surface layer of platinum atoms. The invention particularly relates to such particles having a palladium, palladium alloy, gold alloy, or rhenium alloy core encapsulated by an atomic monolayer of platinum. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

  1. Chromium (VI) adsorption on boehmite

    Energy Technology Data Exchange (ETDEWEB)

    Granados-Correa, F. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)], E-mail: fgc@nuclear.inin.mx; Jimenez-Becerril, J. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)

    2009-03-15

    Boehmite was synthesized and characterized in order to study the adsorption behavior and the removal of Cr(VI) ions from aqueous solutions as a function of contact time, initial pH solution, amount of adsorbent and initial metal ion concentration, using batch technique. Adsorption data of Cr(VI) on the boehmite were analyzed according to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption models. Thermodynamic parameters for the adsorption system were determinated at 293, 303, 313 and 323 K temperatures. The kinetic values and thermodynamic parameters from the adsorption process show that the Cr(VI) ions adsorption on boehmite is an endothermic and spontaneous process. These results show that the boehmite could be considered as a potential adsorbent for chromium ions in aqueous solutions.

  2. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    composition of contemporaneous seawater. Marine carbonates are ubiquitous throughout Earth’s rock record rendering them a particularly interesting archive for constraining past changes in ocean chemistry. This thesis includes an investigation of the fractionation behavior of Cr isotopesduring coprecipitation......Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...... related to the rise of oxygen and the evolution of the biosphere. However, before the Cr isotopesystem can be applied to faithfully delineate paleo-environmental changes, careful assessment of the signal robustness and a thorough understanding of the Cr cycle in Earth system processes is necessary...

  3. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    composition of contemporaneous seawater. Marine carbonates are ubiquitous throughout Earth’s rock record rendering them a particularly interesting archive for constraining past changes in ocean chemistry. This thesis includes an investigation of the fractionation behavior of Cr isotopesduring coprecipitation......Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...... related to the rise of oxygen and the evolution of the biosphere. However, before the Cr isotopesystem can be applied to faithfully delineate paleo-environmental changes, careful assessment of the signal robustness and a thorough understanding of the Cr cycle in Earth system processes is necessary...

  4. CHROMIUM CONCENTRATION IN TEHRAN ELECTROPLATING PLANTS

    Directory of Open Access Journals (Sweden)

    M. Ghiasseddin

    1988-12-01

    Full Text Available Hazards of soluable hexa and trivalent chromium have been documented by many investigators. But there was no information regarding safety of about 5000 workers at exposure risk to chromium in 600 primitive electroplating work shops of Tehran. During this study more than 70% of work shops were inactive due to some of their own problems. Out of active plants those that were relatively more cooperative 43 manual and 3 semi automatic were investigated for chromium concentration both by personal and environmental Sampling. The Samples were analyzed by AAS and cholormetry. In 30% of personal and 40% of environmental samples both total and Cr+6 were higher than ACGIH’S TLV. In one of semiautomatic plant Cr=6 was as high as 0.71 mg/m.3.Regarding injuries, following observations were made: Nasal wound 85%, skin irritation 73% , Dermatitis 35% and some other chromium related injuries including 2 cases of Septum perforations.

  5. Potentiometry: A Chromium (III) -- EDTA Complex

    Science.gov (United States)

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  6. Localized Corrosion of Chromium Coated Steel

    NARCIS (Netherlands)

    Zhang, X.; Beentjes, P.; Mol, A.; Terryn, H.

    2006-01-01

    In this paper, we report on the studies of the local corrosion behaviour of chromium-coated ultra low carbon steel in NaCl solution using polarization, electrochemical impedance spectroscopy (EIS) and SVET.

  7. AEROSOL BEHAVIOR IN CHROMIUM WASTE INCINERATION

    Institute of Scientific and Technical Information of China (English)

    Suyuan Yu

    2003-01-01

    Cr2O3 is considered as the dominant incineration product during the combustion disposal of chromium waste. A hydrogen/air diffusion flame was employed to simulate the industrial process of incineration. Cr2O3 aerosols were generated inside the flame by the gas phase reaction of chromium and oxygen. Chromium came from the rapid decomposition of chromium hexacarbonyl (Cr(CO)6) at room temperature and was carried into the combustion chamber by hydrogen. Aerosol and clusters can then be easily formed in the flame by nucleation and coagulation. A two dimensional Discrete-Sectional Model (DSM) was adopted to calculate the Cr2O3 aerosol behavior. The experimental measurement method was Dynamic Light Scattering. The numerically predicted results agreed well with those of the experimental measurement. Both results show that the Cr2O3 aerosol size reached about 70 nanometers at the flame top.

  8. Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, Low-Carbon Nickel-Chromium-Molybdenum-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Tungsten, and Low-Carbon Nickel-Molybdenum-Chromium Alloy Plate, Sheet, and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, Low-Carbon Nickel-Chromium-Molybdenum-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Tungsten, and Low-Carbon Nickel-Molybdenum-Chromium Alloy Plate, Sheet, and Strip

  9. Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Molybdenum-Chromium, Low-Carbon Nickel-Molybdenum-Chromium-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, and Low-Carbon Nickel-Chromium-Molybdenum-Tungsten Alloy Rod

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Molybdenum-Chromium, Low-Carbon Nickel-Molybdenum-Chromium-Tantalum, Low-Carbon Nickel-Chromium-Molybdenum-Copper, and Low-Carbon Nickel-Chromium-Molybdenum-Tungsten Alloy Rod

  10. Inhalation cancer risk assessment of cobalt metal.

    Science.gov (United States)

    Suh, Mina; Thompson, Chad M; Brorby, Gregory P; Mittal, Liz; Proctor, Deborah M

    2016-08-01

    Cobalt compounds (metal, salts, hard metals, oxides, and alloys) are used widely in various industrial, medical and military applications. Chronic inhalation exposure to cobalt metal and cobalt sulfate has caused lung cancer in rats and mice, as well as systemic tumors in rats. Cobalt compounds are listed as probable or possible human carcinogens by some agencies, and there is a need for quantitative cancer toxicity criteria. The U.S. Environmental Protection Agency has derived a provisional inhalation unit risk (IUR) of 0.009 per μg/m(3) based on a chronic inhalation study of soluble cobalt sulfate heptahydrate; however, a recent 2-year cancer bioassay affords the opportunity to derive IURs specifically for cobalt metal. The mechanistic data support that the carcinogenic mode of action (MOA) is likely to involve oxidative stress, and thus, non-linear/threshold mechanisms. However, the lack of a detailed MOA and use of high, toxic exposure concentrations in the bioassay (≥1.25 mg/m(3)) preclude derivation of a reference concentration (RfC) protective of cancer. Several analyses resulted in an IUR of 0.003 per μg/m(3) for cobalt metal, which is ∼3-fold less potent than the provisional IUR. Future research should focus on establishing the exposure-response for key precursor events to improve cobalt metal risk assessment.

  11. Cobalt particle size effects in catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.

    2010-01-01

    Aim of the work described in this thesis was first to investigate cobalt particle size effects in heterogeneous catalysis. The main focus was to provide a deeper understanding of the origin of the cobalt particle size effects in Fischer-Tropsch (FT) catalysis in which synthesis gas (H2/CO) is conver

  12. Cobalt Complexes as Antiviral and Antibacterial Agents

    Directory of Open Access Journals (Sweden)

    Eddie L. Chang

    2010-05-01

    Full Text Available Metal ion complexes are playing an increasing role in the development of antimicrobials. We review here the antimicrobial properties of cobalt coordination complexes in oxidation state 3+. In addition to reviewing the cobalt complexes containing polydentate donor ligands, we also focus on the antimicrobial activity of the homoleptic [Co(NH36]3+ ion.

  13. Cobalt Complexes as Antiviral and Antibacterial Agents

    OpenAIRE

    Eddie L. Chang; Christa Simmers; D. Andrew Knight

    2010-01-01

    Metal ion complexes are playing an increasing role in the development of antimicrobials. We review here the antimicrobial properties of cobalt coordination complexes in oxidation state 3+. In addition to reviewing the cobalt complexes containing polydentate donor ligands, we also focus on the antimicrobial activity of the homoleptic [Co(NH3)6]3+ ion.

  14. Cobalt particle size effects in catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.

    2010-01-01

    Aim of the work described in this thesis was first to investigate cobalt particle size effects in heterogeneous catalysis. The main focus was to provide a deeper understanding of the origin of the cobalt particle size effects in Fischer-Tropsch (FT) catalysis in which synthesis gas (H2/CO) is

  15. Attenuation of chromium toxicity by bioremediation technology.

    Science.gov (United States)

    Mohanty, Monalisa; Patra, Hemanta Kumar

    2011-01-01

    Chromium is an important toxic environmental pollutant. Chromium pollution results largely from industrial activities, but other natural and anthropogenic sources also contribute to the problem. Plants that are exposed to environmental contamination by chromium are affected in diverse ways, including a tendency to suffer metabolic stress. The stress imposed by Cr exposure also extends to oxidative metabolic stress in plants that leads to the generation of active toxic oxygen free radicals. Such active free radicals degrade essential biomolecules and distort plant biological membranes. In this chapter, we describe sources of environmental chromium contamination, and provide information about the toxic impact of chromium on plant growth and metabolism. In addition, we address different phytoremediation processes that are being studied for use worldwide, in contaminated regions, to address and mitigate Cr pollution. There has been a long history of attempts to successfully mitigate the toxic effects of chromium-contaminated soil on plants and other organisms. One common approach, the shifting of polluted soil to landfills, is expensive and imposes environmental risks and health hazards of its own. Therefore, alternative eco-friendly bioremediation approaches are much in demand for cleaning chromium-polluted areas. To achieve its cleaning effects, bioremediation utilizes living organisms (bacteria, algae, fungi, and plants) that are capable of absorbing and processing chromium residues in ways which amend or eliminate it. Phytoremediation (bioremediation with plants) techniques are increasingly being used to reduce heavy metal contamination and to minimize the hazards of heavy metal toxicity. To achieve this, several processes, viz., rhizofiltration, phytoextraction, phytodetoxification, phytostabilization, and phytovolatilization, have been developed and are showing utility in practice, or promise. Sources of new native hyperaccumulator plants for use at contaminated

  16. Cobalt Derivatives as Promising Therapeutic Agents

    Science.gov (United States)

    Heffern, Marie C.; Yamamoto, Natsuho; Holbrook, Robert J.; Eckermann, Amanda L.; Meade, Thomas J.

    2013-01-01

    Inorganic complexes are versatile platforms for the development of potent and selective pharmaceutical agents. Cobalt possesses a diverse array of properties that can be manipulated to yield promising drug candidates. Investigations into the mechanism of cobalt therapeutic agents can provide valuable insight into the physicochemical properties that can be harnessed for drug development. This review presents examples of bioactive cobalt complexes with special attention to their mechanisms of action. Specifically, cobalt complexes that elicit biological effects through protein inhibition, modification of drug activity, and bioreductive activation are discussed. Insights gained from these examples reveal features of cobalt that can be rationally tuned to produce therapeutics with high specificity and improved efficacy for the biomolecule or pathway of interest. PMID:23270779

  17. Effect of hexavalent chromium on proliferation and differentiation to adipocytes of 3T3-L1 fibroblasts.

    Science.gov (United States)

    Martini, Claudia N; Brandani, Javier N; Gabrielli, Matías; Vila, María del C

    2014-06-01

    Heavy metals contamination has become an important risk factor for public health and the environment. Chromium is a frequent industrial contaminant and is also used in orthopaedic joint replacements made from cobalt-chromium-alloy. Since hexavalent chromium (Cr(VI)) was reported as genotoxic and carcinogenic in different mammals, to further evaluate its cytotoxicity, we investigated the effect of this heavy metal in the proliferation and differentiation to adipocytes of 3T3-L1 fibroblasts. These cells, after the addition of a mixture containing insulin, dexamethasone and methylisobutylxanthine, first proliferate, a process known as mitotic clonal expansion (MCE), and then differentiate to adipocytes. In this differentiation process a key transcription factor is induced: peroxisome proliferator-activated receptor gamma (PPAR gamma). We found that treatment of 3T3-L1 fibroblasts with potassium chromate inhibited proliferation in exponentially growing cells and MCE as well as differentiation. A decrease in PPAR gamma content, evaluated by western blot and immunofluorescence, was found in cells differentiated in the presence of chromium. On the other hand, after inhibition of differentiation with chromium, when the metal was removed, differentiation was recovered, which indicates that this may be a reversible effect. We also found an increase in the number of micronucleated cells after treatment with Cr(VI) which is associated with genotoxic effects. According to our results, Cr(VI) is able to inhibit proliferation and differentiation to adipocytes of 3T3-L1 fibroblasts and to increase micronucleated cells, which are all indicative of alterations in cellular physiology and therefore, contributes to further elucidate the cytotoxic effects of this heavy metal. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Metal allergen of the 21st century--a review on exposure, epidemiology and clinical manifestations of palladium allergy

    DEFF Research Database (Denmark)

    Faurschou, Annesofie; Menné, Torkil; Johansen, Jeanne D;

    2011-01-01

    Consumers are mainly exposed to palladium from jewellery and dental restorations. Palladium contact allergy is nearly always seen together with nickel allergy, as palladium and nickel tend to cross-react. We aimed to analyse the available palladium patch test data and case reports to determine wh...

  19. Direct access to macroporous chromium nitride and chromium titanium nitride with inverse opal structure.

    Science.gov (United States)

    Zhao, Weitian; DiSalvo, Francis J

    2015-03-21

    We report a facile synthesis of single-phase, nanocrystalline macroporous chromium nitride and chromium titanium nitride with an inverse opal morphology. The material is characterized using XRD, SEM, HR-TEM/STEM, TGA and XPS. Interconversion of macroporous CrN to Cr2O3 and back to CrN while retaining the inverse opal morphology is also demonstrated.

  20. Nanocrystalline Cobalt-Phosphorous Electroplating as an Alternative to Hard Chromium Electroplating

    Science.gov (United States)

    2012-08-01

    Nanocrystalline Co-P Deposits) Plating Tank at FRCSE Temp = 185˚F 7 T-45 Pivot Assy Electrochemical Modeling Plated Pivot Stripped Pivot Chemical...O-Ring nCoP 12-16 Plating/ Grinding Completed for Messier Testing Technical Progress (Endurance Rig Testing) Rod (OD) Cylinder (ID) 14  P-3...Hydraulic PASS - MIL-PRF-680 degreaser PASS - Fluorescent penetrant NDI PASS - Nital Grind burn FAIL *PASS Ammonium persulfate Grind burn etch FAIL

  1. Gallium suboxide vapor attack on chromium, cobalt, molybdenum, tungsten and their alloys at 1200 [degrees] C

    Energy Technology Data Exchange (ETDEWEB)

    Kolman, D. G. (David G.); Taylor, T. N. (Thomas N.); Park, Y. (Youngsoo); Stan, M. (Marius); Butt, D. P. (Darryl P.); Maggiore, C. J. (Carl J.); Tesmer, Joseph R.; Havrilla, G. J. (George J.)

    2004-01-01

    Our prior work elucidated the failure mechanism of furnace materi als (304 SS, 316 SS, and Hastelloy C-276) exposed to gallium suboxide (Ga{sub 2}O) and/or gallium oxide (Ga{sub 2}O{sub 3}) during plutonium - gallium compound processing. Failure was hypothesized to result from concurrent alloy oxidation/Ga compound reduction followed by Ga uptake. The aim of the current work is to screen candidate replacement materials. Alloys Haynes 25 (49 Co - 20 Cr - 15 W - 10 Ni - 3 Fe - 2 Mn - 0.4 Si, wt%), 52 Mo - 48 Re (wt%), 62 W - 38 Cu (wt%), and commercially pure Cr, Co, Mo, W, and alumina were examined. Preliminary assessments of commercially pure W and Mo - Re suggest that these materials may be suitable for furnace construction. Thermodynamics calculations indicating that materials containing Al, Cr, Mn, Si, and V would be susceptible to oxidation in the presence of Ga{sub 2}O were validated by experimental results. In contrast to that reported previously, an alternate reaction mechanism for Ga uptake, which does not require concurrent alloy oxidation, controls Ga uptake for certain materials. A correlation between Ga solubility and uptake was noted.

  2. Phytoremediation of Chromium and Cobalt using Pistia stratiotes: A sustainable approach

    Directory of Open Access Journals (Sweden)

    Santosh Kumar Prajapati

    2012-06-01

    Full Text Available This experimental study showed that aquatic macrophytes, Pistia stratiotes, may be used for phytoremediation of water bodies polluted with heavy metals, Cr and Co in a sustainable way.

  3. Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Norwood, W.P. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada) and Aquatic Ecosystems Protection Research Branch, National Water Research Institute, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)]. E-mail: warren.norwood@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Branch, National Water Research Institute, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2006-10-15

    Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r {sup 2}: 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g{sup -1} appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment. - Bioaccumulation of As, Co, Cr and Mn follow a saturation model in Hyalella azteca and can be useful for environmental assessment.

  4. Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca.

    Science.gov (United States)

    Norwood, W P; Borgmann, U; Dixon, D G

    2006-10-01

    Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r(2): 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g(-1) appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment.

  5. Removal of cobalt, chromium, copper, iron and nickel cations from electroplating waste water by apatite ore

    Energy Technology Data Exchange (ETDEWEB)

    Kargar-Razi, M.; Yahyaabadi, S. [Azad Univ. Tehran (Iran, Islamic Republic of)

    2012-07-01

    In this investigation, the adsorption behavior of natural phosphate rock and it's concentrate with respect to Fe{sup 3+}, Ni{sup 2+}, Co{sup 2+}, Cu{sup 2+} and Cr{sup 3+} has been studied, in order to consider its application to purity of electroplating waste water pollution. The batch mehtod has been employed, using metal concentrations in solution ranging from 2 ppm to 40 ppm with mixing process. The effect of pH, concentration of heavy metals and times (10-20 min) is considered. The results of their removal performance in 40 ppm concentration, pH = 8 and 10 minutes are obtained as Cr{sup 3+} > Cu{sup 2+} > Fe{sup 3+} > Co{sup 2+} > Ni{sup 2+} for phosphate rock and the sequence can be given as Cr{sup 3+} > Fe{sup 3+} > Cu{sup 2+} > Co{sup 2+} > Ni{sup 2+} for phosphate concentrate. It was found that the adsorption phenomena depend on charge density and hydrated ion diameter. The same results show that maximum adsorption in PH = 4.5 and 7 for concentrate. The Langmuir adsorption isotherm constants corresponding to adsorption capacity were found to be as Cr{sup 3+} > Fe{sup 3+} > Cu{sup 2+} > Ni{sup 2+} > Co{sup 2+} for phosphate soil and Cr{sup 3+} > Fe{sup 3+} > Cu{sup 2+} > Co{sup 2+} > Ni{sup 2+} for phosphate concentrate. Sorption of metallic cations are considered in pH 4.5, 7 and 8. The results show that phosphate rock and its concentrate have great potential to remove cations of heavy metal species from electroplating waste water. (orig.)

  6. Fibroblastic activities post implantation of cobalt chromium alloy and pure germanium in rabbits.

    Science.gov (United States)

    Carter, J M; Natiella, J R; Baier, R E; Natiella, R R

    1984-02-01

    Different preimplantation surface finishes were applied to surgical vitallium discs and germanium prisms implanted for 20 days within the back muscles of adult rabbits. Histopathologic analysis of the numbers of nuclei of active fibroblasts immediately adjacent to the implants was carried out. The mean apparent volume fractions (MAVF) for the subdermal implant sites were found to depend on the surface cleanliness of the implant, the cleanest or highest-surface-energy surfaces giving the highest MAVF values for active fibroblasts.

  7. Crystallographically Oriented Cobalt Chromium Tantalum Thin-Film Media for High Areal Density Recording.

    Science.gov (United States)

    Deng, Youping

    In order to develop the techniques for increasing recording areal density, microstructural, magnetic and recording properties of crystallographically-oriented CoCrTa thin-films were investigated. The oriented films included bi-crystal and quad-crystal CoCrTa thin films, which were prepared by sputtering on (100) and (110) single crystal Cr substrates, respectively. A theoretical model was developed to calculate the in-plane torque curves of the oriented films. Based on this model, experimental investigations were conducted on the quad-crystal CoCrTa films. It was found that, by fitting the measured in-plane torque curves of the quad -crystal CoCrTa film, it was possible to determine the magnetocrystalline anisotropy constants (K_{rm u1 } and K_{rm u2}) of the CoCrTa film. The torque curves of quad -crystal films were also found to be indicative of the grain isolation and could be used to optimize the sputtering conditions. Substrate bias changed the film composition and lowered M_{rm s} and K_{rm u1}, while improving grain isolation. A more realistic micromagnetic model, which used the measured values of M_ {rm s} and K_{ rm u1} and took the film's grain-cluster microstructure into account, was developed for the bi-crystal films. The simulation results fitted well with the experimental data. A low-speed contact-recording spin-stand, which utilized a magnetoresistive head, was set up for recording studies on the oriented thin-film media and an isotropic thin-film medium prepared on a NiP/Al substrate. The readback signal from the MR head appeared to have some correlation with the medium anisotropy. The recorded patterns were imaged by magnetic force microscopy. It was found that erased bands formed on the quad-crystal and isotropic thin -film media. On the bi-crystal thin-film media, however, clear erased bands were not observed possibly due to the large head-disk distance.

  8. The Key Technique of Manufacture of Dense Chromium Sesquioxide Refractories

    Institute of Scientific and Technical Information of China (English)

    LIMaoqiang; ZHANGShuying; 等

    1998-01-01

    Dense chromium sesquioxide refractories have widely been used in the kilns for making alkai-free and anti-alkali glass fibers due to their excellent re-sistance to molten glasses.Densifications of chromium sesquioxide during sintering can be blocked by evaporation of chromium trioxide derived from oxidation at high temperature,In this paper the mech-anism of sintering chromium oxide and the process-ing technique for making dense chromium sesquiox-ide refractories are discussed .A process in laboratory scale for making dense chromium sesquioxide bricks is demonstrated.

  9. Nickel acts as an adjuvant during cobalt sensitization

    DEFF Research Database (Denmark)

    Bonefeld, Charlotte Menne; Nielsen, Morten Milek; Vennegaard, Marie T.

    2015-01-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We...... investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found...... that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses...

  10. Hydrodehalogenation of bromo- and chloropyridines over palladium complex and palladium metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gurovets, A.S.; Sharf, V.Z.; Belen' kii, L.I.

    1986-03-01

    The hydrodehalogenation of 2-chloro-, 2-bromo-, 3-bromo, and 3,5-dibromopyridine has been studied in the presence of a palladium complex catalyst immobilized on silica gel, and a Pd/C catalyst. Cleavage of bromine from bromopyridines over the Pd complex is significantly faster than from the bromo-substituted furanes and thiophenes previously studied. Debromination over Pd/C is faster than over the complex catalyst. Over both catalysts 3-bromopyridine debrominates faster than the 2-isomer. When molecular deuterium is used, the respective deuterated pyridines can be obtained.

  11. Corrosion by galvanic coupling between amalgam and different chromium-based alloys.

    Science.gov (United States)

    Ciszewski, Aleksander; Baraniak, Marek; Urbanek-Brychczyńska, Magdalena

    2007-10-01

    In recent years there has been an increase in the use of dental casting alloys in prosthodontic treatment. Many patients have metals or alloys, as well as amalgam fillings, in their mouth, and will have them for many years. The aim of this study was to evaluate and compare, in vitro, the galvanic corrosion behavior of chromium-cobalt alloy (Remanium GM 380) and chromium-nickel alloy (Remanium CS) when bound together or coupled with silver-based amalgam (Amalcap plus). An electrochemical characterization of the alloys was performed by potentiostatic and potentiodynamic methods, i.e. the open circuit potential (OCP), the corrosion potential (E(CORR)), corrosion current density (i(CORR)) and corrosion resistance (R(P)). The electromotive force (EMF) of the bimetallic cells was also tested. Electroanalytical techniques were used to estimate the release of any respective element from the dental alloys under study into the artificial saliva solution. It was found that a bimetallic cell consisting of Remanium CS and Remanium GM 380 alloys has a very low EMF (a few mV) and is not a potential source of galvanic currents in the oral cavity. However, galvanic cells prepared from Amalcap plus and Remanium CS or Remanium GM 380 showed a much greater EMF: 104 and 109mV, respectively. This clearly indicates that in these latter cases it is possible to expect some metal ions in the saliva solution as a result of the work of galvanic currents. It was found, by adsorptive stripping voltammetry analysis, that nickel or cobalt, depending on the alloy used, appeared in the saliva solution and increased in concentration over time. The results indicate that the correct design and use of dental alloys are important when determining the appropriate treatment for a specific patient.

  12. Surface characterization of silver and palladium modified glassy carbon

    Indian Academy of Sciences (India)

    Aleksandra A Perić-Grujić; Olivera M Nešković; Miomir V Veljković; Zoran V Laušević; Mila D Laušević

    2007-12-01

    In this work, the influence of silver and palladium on the surface of undoped, boron doped and phosphorus doped glassy carbon has been studied. The silver and palladium concentrations in solution, after metal deposition, were measured by atomic absorption spectrophotometer. The morphology of metal coatings was characterized by scanning electron microscopy. In order to investigate the nature and thermal stability of surface oxygen groups, temperature-programmed desorption method combined with mass spectrometric analyses, was performed. The results obtained have shown that silver and palladium spontaneously deposit from their salt solutions at the surface of glassy carbon samples. Silver deposits have dendrite structure, whilst palladium forms separate clusters. The highest amount of both silver and palladium deposits at the surface of sample containing the highest quantity of surface oxide complexes. It has been concluded that carboxyl groups and structure defects are responsible for metal reduction. Calculated desorption energies have shown that the surface modification by metal deposition leads to the formation of more stable surface of undoped and doped glassy carbon samples.

  13. Extraction of palladium(Ⅱ) with OTMSO from acidic media

    Institute of Scientific and Technical Information of China (English)

    WU Songping; MENG Shuyuan; GU Guobang; ZHUANG Zhiqiang

    2004-01-01

    The extraction of palladium(Ⅱ) from acidic media with cyclic sulfoxide derivative-α-octyl-tetrahydrothiophene-l-oxide (OTMSO) was investigated. The extraction efficiency of palladination number was studied with slope method. The result indicates that coordination number is 2. FT-IR spectra were used to analyze the structure of complex and coordinated atom in complex. Pd is coordinated with both oxygen and sulfur atom in S=O group in OTMSO .The situation and intensity of peaks contributed by complex prepared from various acidity were different. The recovery of palladium(Ⅱ) with OTMSO from scrap containing palladium was discussed. After silver and bismuth were removed, the feed solution was extracted three times by 40% (volume fraction) OTMSO-kerosene. The loaded organic phase was scrubbed three times,and stripped three times by 2 mol@L-1 NH3·H2O solution.The total recovery of palladium was 99.8%,and the purity of palladium was 99.8%.

  14. Atomistic simulation of helium bubble nucleation in palladium

    Energy Technology Data Exchange (ETDEWEB)

    Wang Liang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu, Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: sfxiao@yahoo.com.cn; Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Deng Huiqiu [Department of Applied Physics, Hunan University, Changsha 410082 (China)

    2009-09-15

    A palladium crystal has been constructed with 11808 atoms. 55 helium atoms occupied the octahedral position of palladium crystal are introduced and retained in a spherical region. Molecular dynamic simulations are performed in a constant temperature and constant volume ensemble (NVT) with temperature controlled by Nose-Hoover thermostat. The interactions between palladium atoms are described with modified analytic embedded atom method (MAEAM), the interactions between palladium atom and helium atom are in the form of Morse potential, and the interactions between helium atoms are in the form of L-J potential function. With the analysis of the radial distribution function (RDF) and microstructure, it reveals that some of helium atoms form a series of clusters with different size, and the nucleation core is random at low temperature, and which is the embryo of helium bubble. Increasing temperature can accelerate the process of bubble nucleation, and the clusters will aggregate and coalesce into a bigger one in which there are no palladium atoms, and it is considered as a helium bubble.

  15. Recovery of Elemental Palladium by Shewanella putrefaciens

    Science.gov (United States)

    Akasaka, S.; Xia, X.; Sawada, K.; Enokida, Y.; Yamamoto, I.; Ohnuki, T.

    2006-12-01

    Microbial reduction of metals plays an important role in environmental behavior and provides a technique for the recovery of metals from industrial wastewater. Recently, demand for platinum group metals (PGMs) increases by their catalytic properties. The extreme rarity of PGMs have led to a growing interest in their recovery. Palladium, one of PGMs, has different oxidation states of Pd(II) and Pd(0). The oxidized form of Pd(II) is soluble, while the reduced form of Pd(0) is insoluble. In this study, microbial reduction of palladium by Fe(III)- reducing bacterium, Shewanella putrefaceins was conducted. This bacterium is known to be capable of reducing metals, such as Mn(IV), U(VI), or Tc(VII) with organic C or H2 as an electron donor. In order to investigate the potential of S. putrefaciens to reduce Pd(II) in solution, resting cells or heat-killed cells were suspended under anaerobic conditions with lactate or H2 as an electron donor. The cells of S. putrefaciens (NBRC3908) were grown in aerobic medium, harvested by centrifugation, and then washed with 25 mmol/dm3 HEPES and 100 mmol/dm3 NaCl (HEPES-NaCl) solution (pH 7.0). The heat-killed cells were autoclaved for 20 min at 121 degrees C. The cell suspension (21.5 mg in dry weight) was resuspended in the HEPES-NaCl solution which contained 1.0 mmol/dm3 Na2PdCl4 (Wako Pure chemical Industries, Ltd). The suspensions were bubbled with N2 for 15 min before 10 mmol/dm3 lactate or 4.8 v/v% H2 was added. The suspensions were then incubated at 30 degrees C. Redox potential (Eh) and pH of the solutions were measured in an inert glove box with Ar gas. Concentration of Pd(II) was measured by Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Deposited Pd and cells were analyzed by X-ray powder diffraction (XRD) and Scanning Electron Microscope (SEM) with Energy-Dispersive Spectroscopy (EDS). Approximately 86% of Pd(II) of the initial concentration was removed from solution by the resting cells within 24 h when

  16. Synthesis of a new complex Chromium (Ⅲ) 2-mercaptonicotinate

    Institute of Scientific and Technical Information of China (English)

    LI Wei; HAO Er-jun; JIANG Yu-qin

    2004-01-01

    Chromium is an essential trace element for mammals[1-3].Diabetes is a chronic disease with major health consequence. Studies show that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF)[4]no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr)[5]So there is potential for the design of new chromium drugs[6].Chromium compounds have been used in medicine for centuries and there is potential for the design of new chromium drugs.2-Mercaptonicotinic acid(MN) displays the interesting biological activity. Chromium( Ⅲ )2-mercaptonicotinate is a common and effective biologically active form of Chromium. The test of biological activity indicated that may be useful in treating of diabetes. In this paper, we reported the The synthesis route is as follow:The structure of the complex has been characterized by IR, elemental analysis, MS,atomic absorption spectroscopy, X-ray powder diffraction and TG-DTA analysis.They indicate that the structure of Chromium 2-mercaptonicotinate.HPLC is used for determination of the purity. Studies show that the complex has a good biological activity for supplement tiny dietary chromium,lowering blood glucose levels, lowering serum lipid levels and increasing lean body mass.

  17. Advances in cobalt complexes as anticancer agents.

    Science.gov (United States)

    Munteanu, Catherine R; Suntharalingam, Kogularamanan

    2015-08-21

    The evolution of resistance to traditional platinum-based anticancer drugs has compelled researchers to investigate the cytostatic properties of alternative transition metal-based compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. This perspective catalogues the development of antiproliferative cobalt complexes, and provides an in depth analysis of their mode of action. Early studies on simple cobalt coordination complexes, Schiff base complexes, and cobalt-carbonyl clusters will be documented. The physiologically relevant redox properties of cobalt will be highlighted and the role this plays in the preparation of hypoxia selective prodrugs and imaging agents will be discussed. The use of cobalt-containing cobalamin as a cancer specific delivery agent for cytotoxins will also be described. The work summarised in this perspective shows that the biochemical and biophysical properties of cobalt-containing compounds can be fine-tuned to produce new generations of anticancer agents with clinically relevant efficacies.

  18. Cobalt-mediated radical polymerization of vinyl monomers: investigation of cobalt-coordination

    OpenAIRE

    2009-01-01

    Controlled Radical Polymerization techniques have been developed to obtain well-defined architectures and to control polymer parameters. Among these systems is Cobalt-Mediated Radical Polymerization (CMRP), which is based on the reversible deactivation of the growing radical chains with a cobalt complex, the cobalt (II) bis(acetylacetonate). The interest of this system is not only due to its ability to control the polymerization of very reactive monomers such as vinyl acetate (VAc) and N-viny...

  19. Flotation of cobalt bearing minerals from a mixed copper-cobalt oxidized ore

    OpenAIRE

    2012-01-01

    M.Tech. (Extraction Metallurgy) The techniques for the flotation of mixed copper and cobalt bearing oxide ores using the sulphidization method in order to recover the oxidized copper and cobalt bearing minerals have been well documented by previous researchers. These processes have been successfully implemented in many of the metallurgical plant operations in the Democratic Republic of Congo (DRC). The mixed copper and cobalt oxidised ores from this region present significant chal-lenges t...

  20. The mechanism of corrosion of palladium-silver binary alloys in artificial saliva.

    Science.gov (United States)

    Joska, L; Marek, M; Leitner, J

    2005-05-01

    Palladium dental casting alloys are alternatives to gold alloys. The aim of this study was to determine the electrochemical behaviour and the corrosion mechanism of binary silver-palladium alloys. Seven binary silver-palladium alloys and pure palladium and silver were tested in a model saliva solution. Electrochemical tests included corrosion potential, polarization resistance, and potentiodynamic polarization measurements. The corrosion products, which may be theoretically formed, were determined by thermodynamic calculation. The behaviour of silver and silver-rich alloys was dominated by the preferential formation of a thiocyanate surface layer, which controlled the free corrosion potential. Palladium dissolved in the form of a thiocyanate complex, but the surface became passivated by either palladium oxide or solid palladium thiocyanate layer, the thermodynamic calculations indicating preference for the oxide. Palladium-rich alloys showed evidence of silver depletion of the surface, resulting in behaviour similar to palladium. Examination of binary silver-palladium alloys has made possible determination of the role of the components of the alloys and model saliva in the corrosion behaviour. The findings are applicable to the more complex commercial dental alloys containing silver and palladium as major components.

  1. 镍基合金电解加工渣泥中镍和钴的回收%Recovery of nickel and cobalt from electromachining sludge of nickel alloy

    Institute of Scientific and Technical Information of China (English)

    王德全; 姜澜

    2001-01-01

    Recovery of nickel and cobalt from electromachining sludge of a nickel alloy was investigated. According to component of the sludge and thermodynamical analysis, the sludge was treated by using a washing—leaching—hydrolysis precipitation process. The results show that soluble compounds such as sodium chloride, sodium nitrate and a part of chromium salts can be washed out from the sludge. In the following sulphuric acid leaching process, nickel, cobalt and chromium in the washed sludge can be leached out, but tungsten and molybdenum remain in the leaching residue. Extraction ratio of nickel and cobalt in the leaching process amounts to 98%. The chromium in the leach solution can be removed as chromium hydroxide by using a hydrolysis-precipitation process and the efficiency of chromium removal reaches 94.44%.%根据镍基合金电解加工渣泥的组成和热力学分析, 用水洗—浸出—水解沉淀工艺处理这种渣泥。 试验结果表明: 氯化钠、 硝酸钠和部分铬盐等可溶性化合物可以从渣泥中洗出; 继而的硫酸浸出过程中, 可将洗后渣泥中的镍、 钴和铬浸出, 而钨和钼留在浸出渣中。 在浸出过程中, 镍和钴的浸出率达98%。 浸出液中的铬可通过水解沉淀法以氢氧化铬的形态除去, 铬的脱除率达94.44%。

  2. Serum chromium levels in gestational diabetes mellitus

    Directory of Open Access Journals (Sweden)

    P G Sundararaman

    2012-01-01

    Full Text Available Objective: To measure serum chromium level in women with gestational diabetes mellitus (GDM from Chennai, South India. Materials and Methods: Thirty women with gestational diabetes, 60 age matched controls. Inclusion criteria: Gestational age 22-28 weeks, age group 20-35 years. Exclusion Criteria: Gestational age beyond 28 weeks, malnutrition or presence of infection. Serum chromium was measured using inductive couple plasma emission spectrometer. Results: Serum chromium levels of women with GDM, 1.59+/-0.02 ng/ml (range: 0.16-4.0 ng/ml were lower than in controls (4.58+/-0.62 ng/ml; range 0.82-5.33 ng/ml (P < 0.001. However, there were no significant differences among cases and controls when subdivided by parity. Conclusions: Women with GDM from a South Indian city had lower levels of serum chromium compared to pregnant women without GDM. Studies may be done whether chromium supplementation is useful in this group of women.

  3. Local magnetism in palladium bionanomaterials probed by muon spectroscopy.

    Science.gov (United States)

    Creamer, Neil J; Mikheenko, Iryna P; Johnson, Clive; Cottrell, Stephen P; Macaskie, Lynne E

    2011-05-01

    Palladium bionanomaterial was manufactured using the sulfate-reducing bacterium, Desulfovibrio desulfuricansm, to reduce soluble Pd(II) ions to cell-bound Pd(0) in the presence of hydrogen. The biomaterial was examined using a Superconducting Quantum Interference Device (SQUID) to measure bulk magnetisation and by Muon Spin Rotation Spectroscopy (µSR) which is uniquely able to probe the local magnetic environment inside the sample. Results showed behaviour attributable to interaction of muons both with palladium electrons and the nuclei of hydrogen trapped in the particles during manufacture. Electronic magnetism, also suggested by SQUID, is not characteristic of bulk palladium and is consistent with the presence of nanoparticles previously seen in electron micrographs. We show the first use of μSR as a tool to probe the internal magnetic environment of a biologically-derived nanocatalyst material.

  4. Mechanism of extracting palladium(Ⅱ) with cyclic sulfoxide derivatives

    Institute of Scientific and Technical Information of China (English)

    吴松平; 孟淑媛; 古国榜; 庄志强; 刘会冲

    2004-01-01

    The extraction ability of palladium( Ⅱ ) from acidic media with cyclic sulfoxide derivatives-α-Dodecyl-tetrahydrothiophene 1-Oxide (DTMSO), α-octyl-tetrahydrothiophene 1-Oxide (OTMSO) and α-butyl-tetrahydro-thiophene-1-Oxide (BTMSO) was investigated. The extracting efficiency of cyclic sulfoxide derivatives decreased with the increasing of acidity in the lower acidity, and the efficiency became stable with the change of acidity in the higher acidity. The extraction reaction of palladium( Ⅱ )with DTMSO is exothermic, and extraction reaction of pal-ladium( Ⅱ ) is endothermic when OTMSO or BTMSO were used as extracting reagents. The coordination number was studied by slope method. The results indicate that coordination number is 2, and the composition of complex is Pd is coordinated with both oxygen and sulfur atom in S=O group in sulfoxide derivatives.

  5. Palladium-Catalyzed Modification of Unprotected Nucleosides, Nucleotides, and Oligonucleotides

    Directory of Open Access Journals (Sweden)

    Kevin H. Shaughnessy

    2015-05-01

    Full Text Available Synthetic modification of nucleoside structures provides access to molecules of interest as pharmaceuticals, biochemical probes, and models to study diseases. Covalent modification of the purine and pyrimidine bases is an important strategy for the synthesis of these adducts. Palladium-catalyzed cross-coupling is a powerful method to attach groups to the base heterocycles through the formation of new carbon-carbon and carbon-heteroatom bonds. In this review, approaches to palladium-catalyzed modification of unprotected nucleosides, nucleotides, and oligonucleotides are reviewed. Polar reaction media, such as water or polar aprotic solvents, allow reactions to be performed directly on the hydrophilic nucleosides and nucleotides without the need to use protecting groups. Homogeneous aqueous-phase coupling reactions catalyzed by palladium complexes of water-soluble ligands provide a general approach to the synthesis of modified nucleosides, nucleotides, and oligonucleotides.

  6. Selective palladium electrochemical deposition onto AFM-scratched silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Santinacci, L.; Djenizian, T.; Hildebrand, H.; Ecoffey, S.; Mokdad, H.; Campanella, T.; Schmuki, P

    2003-09-30

    The present work investigates the selective electrochemical deposition of palladium nano-structures into scratches produced through thin oxide layers covering p-Si (1 0 0) surfaces. Using an atomic force microscope equipped with a single-crystalline diamond tip scratches in the 100 nm range were produced through a 10 nm thick dry oxide layer. Pd deposition was carried out in PdCl{sub 2} (0.01 g l{sup -1})+HCl (0.1 M) by cathodic potential steps. Investigation of the palladium nucleation and growth processes onto silicon surfaces is presented. Under optimized conditions sub-100 nm palladium structures can be obtained with a very high selectivity.

  7. Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.; Schoonheydt, R.A.

    1996-01-01

    Focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides. Characterization of the molecular structures of chromium; Mechanics of hydrogenation-dehydrogenation reactions; Mobility and reactivity on oxidic surfaces.

  8. Mechanochemical Preparation of Cobalt Nanoparticles through a Novel Intramolecular Reaction in Cobalt(II) Complexes

    OpenAIRE

    2015-01-01

    A novel solid state reaction involving a series of cobalt(II) hydrazine-azides has been used to prepare metallic cobalt nanoparticles. The reactions of [Co(N2H4)(N3)2], [Co(N2H4)2(N3)2], and [Co(N2H4)(N3)Cl]·H2O via NaOH, KOH as reactants were carried out in the solid state. These complexes undergo an intramolecular two-electron oxidation-reduction reaction at room temperature, producing metallic cobalt nanoparticles (Co1–Co6). The aforementioned complexes contain cobalt(II) that is an oxidiz...

  9. Bromoporphyrins as versatile synthons for modular construction of chiral porphyrins: cobalt-catalyzed highly enantioselective and diastereoselective cyclopropanation.

    Science.gov (United States)

    Chen, Ying; Fields, Kimberly B; Zhang, X Peter

    2004-11-17

    5,10-Bis(2',6'-dibromophenyl)porphyrins bearing various substituents at the 10 and 20 positions were demonstrated to be versatile synthons for modular construction of chiral porphyrins via palladium-catalyzed amidation reactions with chiral amides. The quadruple carbon-nitrogen bond formation reactions were accomplished in high yields with different chiral amide building blocks under mild conditions, forming a family of D2-symmetric chiral porphyrins. Cobalt(II) complexes of these chiral porphyrins were prepared in high yields and shown to be active catalysts for highly enantioselective and diastereoselective cyclopropanation under a practical one-pot protocol (alkenes as limiting reagents and no slow addition of diazo reagents).

  10. Palladium-Catalyzed Arylation of Fluoroalkylamines

    Science.gov (United States)

    Brusoe, Andrew T.; Hartwig, John F.

    2015-01-01

    We report the synthesis of fluorinated anilines by palladium-catalyzed coupling of fluoroalkylamines with aryl bromides and aryl chlorides. The products of these reactions are valuable because anilines typically require the presence of an electron-withdrawing substituent on nitrogen to suppress aerobic or metabolic oxidation, and the fluoroalkyl groups have steric properties and polarity distinct from those of more common electron-withdrawing amide and sulfonamide units. The fluoroalkylaniline products are unstable under typical conditions for C–N coupling reactions (heat and strong base). However, the reactions conducted with the weaker base KOPh, which has rarely been used in cross-coupling to form C–N bonds, occurred in high yield in the presence of a catalyst derived from commercially available AdBippyPhos and [Pd(allyl)Cl]2. Under these conditions, the reactions occur with low catalyst loadings (<0.50 mol % for most substrates) and tolerate the presence of various functional groups that react with the strong bases that are typically used in Pd-catalyzed C–N cross-coupling reactions of aryl halides. The resting state of the catalyst is the phenoxide complex, (BippyPhosPd(Ar)OPh); due to the electron-withdrawing property of the fluoroalkyl substituent, the turnover-limiting step of the reaction is reductive elimination to form the C–N bond. PMID:26065341

  11. On the structure of small palladium particles

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, R.; Avalos-Borja, M.; Schabes-Retchkiman, P.; Romeu, D.; Jose-Yacaman, M. (Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica); Ponce, F. (Xerox Palo Alto Research Center, CA (USA))

    1989-09-01

    The study of small noble metal particles is becoming increasingly important in many fields in physics (1). The advent of high-resolution electron microscopy (HREM) has allowed a deeper understanding of structural aspects of small particles. This work reports the study of particles of palladium with a diameter less than 3 nm. Specimens were prepared by in-situ deposition of Pd onto thin carbon films under near-UHV conditions in the specimen preparation chamber. Faulted decahedral MTP was grown using a recursive (R) growth model which generates infinite, space-filling structures reproducing the structure of crystals, twinned particles and quasicrystals. R growth consists of the formation of a cluster by iterative addition of points (atoms) from a given star vector. The method presented sheds some light on a point that has been controversial in the past about the nature of MTP's. Some authors have claimed that these structures can be considered as FCC twins with a disclination to close the resulting gap. The fact that they can be obtained quite simply from stable smaller units appears to make the disclination unnecessary.

  12. Residual Chromium in Leather by Instrumental Neutron Activation Analysis

    OpenAIRE

    S. Okoh; I. O. Okunade; D. J. Adeyemo; Ahmed, Y A; A. A. Audu; E. Amali

    2012-01-01

    Problem statement: Most tanning processes employ the use of chromium sulphate. For chromium tanned leather, finished products may contain high amount of residual chromium. This may pose some health hazards, since chromium is known to be toxic at elevated concentration. This justifies the need for the study. Approach: Various samples of leather were collected from a tannery, a leather crafts market, a leather dump site and from local tanners all in Kano, Nigeria in 2009. The samples were irrad...

  13. Role of Palladium in the Redox Electrochemistry of Ferrocene Monocarboxylic Acid Encapsulated Within ORMOSIL Networks

    Directory of Open Access Journals (Sweden)

    B. Upadhyay

    2005-07-01

    Full Text Available We report herein the effect of palladium on the redox electrochemistry of ferrocene monocarboxylic acid encapsulated within an organically modified sol-gel glass network (ORMOSIL. It has been found that amount of palladium and its geometrical distribution significantly alter the redox electrochemistry of FcMCA. The geometrical distribution of palladium has been controlled by two methods: (i palladium is allowed to link within nanostructured network of the ORMOSIL which was subsequently availed from the reactivity of palladium chloride and trimethoxysilane; (ii palladium powder is encapsulated together FcMCA thus allowing the presence of palladium within the nanoporous domain. The content of palladium is varied by controlling the reaction dynamics of palladium chloride and trimethoxysilane interaction. For this we initially allowed to trigger hydrolysis, condensation and poly-condensation of trimethoxysilane and dimethyldiethoxysilane in acidic medium and subsequently partially dried ORMOSIL film was allowed to interact with palladium chloride. Even with partially dried ORMOSIL derived from trimethoxysilane and dimethyldiethoxysilane undergoes rapid interaction with palladium chloride and the transparent color of ORMOSIL changed to a black colour due to the formation of palladium silicon linkage. The palladium-silicon linkage has been identified by NMR, UV-VIS and transmission electron spectroscopy. The electrochemistry of FcMCA encapsulated within such an ORMOSIL matrix has been studied. Excellent redox electrochemistry of ferrocene monocarboxylic acid having peak potential separation tending to 0 for a multilayered electrode was investigated. The palladium content has been found to affect the redox electrochemistry of ferrocene as well as electrocatalytic efficiency of new ORMOSIL material. The electroanalysis of NADH is reported. The modified electrode is very sensitive to NADH with lowest detection limit of < 1 μM.

  14. Morphological Study Of Palladium Thin Films Deposited By Sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Salcedo, K L; Rodriguez, C A [Grupo Plasma Laser y Aplicaciones, Ingenieria Fisica, Universidad Tecnologica de Pereira (Colombia); Perez, F A [WNANO, West Virginia University (United States); Riascos, H [Grupo Plasma Laser y Aplicaciones, Departamento de Fisica, Universidad Tecnologica de Pereira (Colombia)

    2011-01-01

    This paper presents a morphological analysis of thin films of palladium (Pd) deposited on a substrate of sapphire (Al{sub 2}O{sub 3}) at a constant pressure of 3.5 mbar at different substrate temperatures (473 K, 523 K and 573 K). The films were morphologically characterized by means of an Atomic Force Microscopy (AFM); finding a relation between the roughness and the temperature. A morphological analysis of the samples through AFM was carried out and the roughness was measured by simulating the X-ray reflectivity curve using GenX software. A direct relation between the experimental and simulation data of the Palladium thin films was found.

  15. Phase Transitions in Even-Even Palladium Isotopes

    Directory of Open Access Journals (Sweden)

    Diab S. M.

    2009-01-01

    Full Text Available The positive and negative parity states of the even-even palladium isotopes were stud- ied within the frame work of the interacting boson approximation model (IBA-1. The energy spectra, potential energy surfaces, electromagnetic transition probabilities, back bending and staggering effect have been calculated. The potential energy surfaces show smooth transition from vibrational-like to gamma-soft and finally to rotational-like nu- clei. Staggering effectle, has been observed between the positive and negative parity states in palladium isotopes. The agreement between theoretical predictions and exper- imental values are fairly good.

  16. Palladium based nanomaterials for enhanced hydrogen spillover and storage

    Directory of Open Access Journals (Sweden)

    Suresh K. Konda

    2016-03-01

    Full Text Available Hydrogen storage remains one of the most challenging prerequisites to overcome toward the realization of a hydrogen based economy. The use of hydrogen as an energy carrier for fuel cell applications has been limited by the lack of safe and effective hydrogen storage materials. Palladium has high affinity for hydrogen sorption and has been extensively studied, both in the gas phase and under electrochemical conditions. In this review, recent advancements are highlighted and discussed in regard to palladium based nanomaterials for hydrogen storage, as well as the effects of hydrogen spillover on various adsorbents including carbons, metal organic frameworks, covalent organic frameworks, and other nanomaterials.

  17. Hemocompatibility Improvement of Chromium-Bearing Bare-Metal Stent Platform After Magnetoelectropolishing

    Science.gov (United States)

    Rokicki, Ryszard; Haider, Waseem; Maffi, Shivani Kaushal

    2015-01-01

    Research was undertaken to determine the influence of the increased content of chromium in the outermost passive layer of magneto-electrochemically refined Co-Cr alloy L-605 surface on its hemocompatibility. The chemistry, roughness, surface energy, and wettability of conventionally electropolished (EP) and magnetoelectropolished (MEP) samples were studied with x-ray photoelectron spectroscopy (XPS), open circuit potential, atomic force microscopy, and contact angle meter. In vitro hemocompatibility of tested material surfaces was assessed using two important indicators of vascular responses to biomaterial, namely endothelialization and platelets adhesion. The endothelialization was assessed by seeding and incubating samples with human umbilical vein endothelial cells (HUVEC) for 3 days before counting and observing them under a fluorescent microscope. The platelet (rich plasma blood) adhesion and activation test on EP and MEP L-605 alloy surfaces was assessed using a laser scanning confocal microscope. The XPS analysis of MEP samples showed significant enrichment of the passive layer with Cr and O when compared with the EP one. The amount of other elements in the passive layer did not show a significant difference between EP and MEP treatments. The adhesion of HUVEC cells shows remarkable affinity to surfaces enriched in Cr (MEP) with almost 100% confluency. In addition, the number of platelets that adhered to standard EP surfaces was higher compared to the MEP surface. The present study shows that the chromium-enriched surface of cobalt-chromium alloy L-605 by the magnetoelectropolishing process tremendously improves surface hemocompatibility with regard to stent functionality by enhanced endothelialization and lower platelet adhesion and should be taken under consideration as an alternative surface of biodegradable polymer drug-eluting stents, polymer-free drug-eluting stents as well as bare-metal stents.

  18. Environmental Factors Affecting Chromium-Manganese Oxidation-Reduction Reactions in Soil

    Institute of Scientific and Technical Information of China (English)

    D.O.P.TREBIEN; L.BORTOLON; M.J.TEDESCO; C.A.BISSANI; F.A.O.CAMARGO

    2011-01-01

    Disposal of chromium (Cr) hexavalent form, Cr(Ⅵ), in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr(Ⅵ) can be highly toxic to plants, animals, and humans. In order to explore soil conditions that lead to Cr(Ⅵ) generation, this study were performed using a Paleudult (Dystic Nitosol) from a region that has a high concentration of tannery operations in the Rio Grande do Sul State, southern Brazil. Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr(Ⅵ) formation and release and manganese (Mn) oxide reduction with a salt of chromium chloride (CrCl3) and tannery sludge as inorganic and organic sources of Cr(Ⅲ), respectively. The amount of Cr(Ⅲ) oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn(Ⅲ/Ⅳ) oxides were more stable. Soluble organic compounds in soil decreased Cr(Ⅵ) formation due to Cr(Ⅲ) complexation. This mechanism also resulted in the decrease in the oxidation of Cr(Ⅲ) due to the tannery sludge additions. Chromium(Ⅲ) oxidation to Cr(Ⅵ) at the solid/solution interface involved the following mechanisms:the formation of a precursor complex on manganese (Mn) oxide surfaces, followed by electron transfer from Cr(Ⅲ) to Mn(Ⅲ or Ⅳ),the formation of a successor complex with Mn(Ⅱ) and Cr(Ⅵ), and the breakdown of the successor complex and release of Mn(Ⅱ) and Cr(Ⅵ) into the soil solution.

  19. 一种含钯物料中钯的回收%Recovery of Palladium from a Palladium Material

    Institute of Scientific and Technical Information of China (English)

    徐涛

    2015-01-01

    The traditional method of ammonium chloride recovery of palladium process was improved. By adding oxidant palladium adjusted to Pd(IV) morphology, and speed of adding HCl was slowed down to reduce Pd content in tail solution. The recovery rate palladium reached 98.5%.%对传统的氯化铵法回收钯工艺进行了改进,采用添加氧化剂的方式将钯调整为Pd(Ⅳ)形态,控制加入盐酸的速度,减少钯在尾液中的量,使钯的回收率达到98.5%以上。

  20. Hexavalent and trivalent chromium in leather: What should be done?

    Science.gov (United States)

    Moretto, Angelo

    2015-11-01

    Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions.

  1. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2010-11-01

    ... COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... chromium from Japan. SUMMARY: The Commission hereby gives notice that it has instituted a review pursuant... revocation of the antidumping duty order on superalloy degassed chromium from Japan would be likely to lead...

  2. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Science.gov (United States)

    2010-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts. ...

  3. Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625), Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219), and Nickel-Chromium-Molybdenum-Tungsten Alloy (UNS N06650) Rod and Bar

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625), Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219), and Nickel-Chromium-Molybdenum-Tungsten Alloy (UNS N06650) Rod and Bar

  4. Cobalt-related defects in silicon

    Science.gov (United States)

    Gibbons, T. M.; Backlund, D. J.; Estreicher, S. K.

    2017-01-01

    Transition metals from the 3d series are unavoidable and unwanted contaminants in Si-based devices. Cobalt is one of the most poorly understood impurities with incomplete experimental information and few theoretical studies. In this contribution, the properties of interstitial cobalt (Coi) in Si and its interactions with the vacancy, self-interstitial, hydrogen, and substitutional boron are calculated using the first-principles tools. The stable configurations, gap levels, and binding energies are predicted. The activation energy for diffusing Coi is calculated with the nudged-elastic-band method and found to be slightly lower than that of interstitial copper and nickel. The binding energies and gap levels of the substitutional cobalt (Cos) and of the {Cos,H} and {Cos,H,H} complexes are close to the experimental data. The properties of the cobalt-boron pair are calculated.

  5. Transport properties of cobalt at low temperatures

    DEFF Research Database (Denmark)

    Radharkishna, P.; Nielsen, Mourits

    1965-01-01

    Measurements are made of electrical resistivity, absolute thermoelectric power, and thermal conductivity of polycrystalline cobalt between 1.2 and 6 K; results are discussed on basis of inter-electronic scattering.......Measurements are made of electrical resistivity, absolute thermoelectric power, and thermal conductivity of polycrystalline cobalt between 1.2 and 6 K; results are discussed on basis of inter-electronic scattering....

  6. Strategies for chromium bioremediation of tannery effluent.

    Science.gov (United States)

    Garg, Satyendra Kumar; Tripathi, Manikant; Srinath, Thiruneelakantan

    2012-01-01

    Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and

  7. New mixed aluminium–chromium diarsenate

    Directory of Open Access Journals (Sweden)

    Mohamad Alem Bouhassine

    2017-03-01

    Full Text Available Potassium chromium aluminium diarsenate, KCr1/4Al3/4As2O7, was prepared by solid-state reaction. The structure consists of (Cr1/4/Al3/4O6 octahedra and As2O7 diarsenate groups sharing corners to build up a three-dimensional anionic framework. The potassium cations are located in wide channels running along the c-axis direction. The crystal structure is isostructural with the triclinic AIMIIIX2O7 (AI = alkali metal; MIII = Al, Cr, Fe; X = As, P compounds. However, the MIII octahedrally coordinated site is 25% partially occupied by chromium and 75% by aluminium.

  8. Studying chromium biosorption using arabica coffee leaves

    Directory of Open Access Journals (Sweden)

    Luis Carlos Florez García

    2010-05-01

    Full Text Available This work was aimed at providing an alternative for removing heavy metals such as chromium from waste water (effluent from the leather industry and galvanoplasty (coating with a thin layer of metal by electrochemical means, using coffee leaves as bio- mass. Using arabica coffee (Castle variety leaves led to 82% chromium removal efficiency for 1,000 mg/L synthetic dissolutions in 4 pH dissolution operating conditions, 0 rpm agitation, 0.149 mm diameter biomass particle size and 0.85 g/ml biomass / dissolution volume ratio.

  9. Nickel acts as an adjuvant during cobalt sensitization.

    Science.gov (United States)

    Bonefeld, Charlotte Menné; Nielsen, Morten Milek; Vennegaard, Marie T; Johansen, Jeanne Duus; Geisler, Carsten; Thyssen, Jacob P

    2015-03-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses in the draining lymph nodes compared to mice sensitized with cobalt alone. In contrast, the presence of cobalt during nickel sensitization only induced an increased CD8(+) T cell proliferation during challenge to nickel. Thus, the presence of nickel during cobalt sensitization potentiated the challenge response against cobalt more than the presence of cobalt during sensitization to nickel affected the challenge response against nickel. Taken together, our study demonstrates that sensitization with a mixture of nickel and cobalt leads to an increased immune response to both nickel and cobalt, especially to cobalt, and furthermore that the adjuvant effect appears to correlate with the inflammatory properties of the allergen. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Palladium and platinum-palladium bi-layer based counter electrode for dye-sensitized solar cells with modified photoanode

    Science.gov (United States)

    Mokurala, Krishnaiah; Kamble, Anvita; Nemala, Siva Sankar; Bhargava, Parag; Mallick, Sudhanshu

    2015-06-01

    Dye sensitized solar cells (DSSCs) were fabricated with palladium (Pd) and platinum-palladium (Pt-Pd) bi-layer as counter electrodes, respectively. Effects of photoanode thickness and morphology on device performance were studied. DSSCs fabricated with Pd and Pd-Pt as counter electrode (CE) showed photo conversion efficiency of 4.30% and 6.20%, respectively as compared to Platinum (Pt) based CE which showed 6.65% efficiency. Lower device performance was explained with help of cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements of the cells.

  11. Intolerability of cobalt salt as erythropoietic agent.

    Science.gov (United States)

    Ebert, Bastian; Jelkmann, Wolfgang

    2014-03-01

    Unfair athletes seek ways to stimulate erythropoiesis, because the mass of haemoglobin is a critical factor in aerobic sports. Here, the potential misuse of cobalt deserves special attention. Cobalt ions (Co(2+) ) stabilize the hypoxia-inducible transcription factors (HIFs) that increase the expression of the erythropoietin (Epo) gene. Co(2+) is orally active, easy to obtain, and inexpensive. However, its intake can bear risks to health. To elaborate this issue, a review of the pertinent literature was retrieved by a search with the keywords 'anaemia', 'cobalt', 'cobalt chloride', 'erythropoiesis', 'erythropoietin', 'Epo', 'side-effects' and 'treatment', amongst others. In earlier years, cobalt chloride was administered at daily doses of 25 to 300 mg for use as an anti-anaemic agent. Co(2+) therapy proved effective in stimulating erythropoiesis in both non-renal and renal anaemia, yet there were also serious medical adverse effects. The intake of inorganic cobalt can cause severe organ damage, concerning primarily the gastrointestinal tract, the thyroid, the heart and the sensory systems. These insights should keep athletes off taking Co(2+) to stimulate erythropoiesis.

  12. [Are the cobalt hip prosthesis dangerous?].

    Science.gov (United States)

    Mistretta, Virginie; Kurth, William; Charlier, Corinne

    The placement of a hip prosthesis is one of the most common orthopedic surgical procedures. Some implants contain metal and are therefore capable of releasing metal particles like cobalt in patients who wear metal prostheses. Cobalt can be responsible of local toxicity (including metallosis, hypersensitivity reaction, and benign tumor) or systemic toxicity (including cardiomyopathy, polycythemia, hypothyroidism, and neurological disorders). To monitor potential toxicity of metal hip prostheses, an annual monitoring of patients implanted is recommended and includes clinical examination, radiological examination and blood cobalt determination. The cobalt concentration in blood allows to estimate the risk of toxicity and to evaluate the performance of the implant. The currently recommended threshold value is equal to 7 µg of cobalt per liter of blood. Our study, conducted on 251 patients over a period of 4 years, has shown that the cobalt concentration average was 2.51 µg/l in blood, with 51 patients having a cobaltemia higher than the threshold of 7 µg/l. © 2016 médecine/sciences – Inserm.

  13. On the corrosion behavior and biocompatibility of palladium-based dental alloys

    Science.gov (United States)

    Sun, Desheng

    Palladium-based alloys have been used as dental restorative materials for about two decades with good clinical history. But there have been clinical case reports showing possible allergy effects from these alloys. The aim of this study was to characterize the corrosion behavior and mechanisms of several palladium-based dental alloys by potentiodynamic polarization methods, electrochemical impedance spectroscopy (EIS), and scanning Kelvin probe force microscopy/atomic force microscopy (SKPFM/AFM), and to evaluate their biocompatibility by a cell culture technique and an animal model. Using SKPFM/AFM and scanning electron microscopy, the Ru-enriched phase from the use of ruthenium as a grain-refining element was identified as being slightly more noble than the palladium solid solution matrix in a high-palladium alloy. Other secondary precipitates that exist in the microstructures of these high-palladium alloys have minimal differences in Volta potential compared to the matrix. For high-palladium alloys, corrosion is generally uniform due to the predominant palladium content in the different phases. Potentiodynamic polarization and EIS have shown that representative palladium-silver alloys have low corrosion tendency and high corrosion resistance, which are equivalent to a well-known high-noble gold-palladium alloy in simulated body fluid and oral environments. The palladium-silver alloys tested are resistant to chloride ion corrosion. Passivation and dealloying have been identified for all of the tested palladium-silver alloys. The great similarity in corrosion behavior among the palladium-silver alloys is attributed to their similar chemical compositions. The variation in microstructures of palladium-silver alloys tested does not cause significant difference in corrosion behavior. The corrosion resistance of these palladium-silver alloys at elevated potentials relevant to oral environment is still satisfactory. The release of elements from representative dental

  14. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    National Research Council Canada - National Science Library

    Anđelković Darko H; Anđelković Tatjana D; Nikolić Ružica S; Purenović Milovan M; Blagojević Srđan D; Bojić Aleksandar Lj; Ristić Milica M

    2012-01-01

    Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction...

  15. A novel method to synthesize cobalt oxide (Co3O4) nanowires from cobalt (Co) nanobowls

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A novel method suitable for the synthesis of the cobalt oxide (Co3O4) nanowires at targeted regions is presented in this report. Cobalt (Co) nanobowls synthesized by colloidal crystal directed assembly were transformed into Co3O4 nanowires by a simple heat treatment process. Co nanobowls exhibited...

  16. Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil

    2010-01-01

    Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure.......Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure....

  17. Removal of chromium from wastewater by reverse osmosis

    Science.gov (United States)

    Çimen, Aysel

    2015-07-01

    Removal of chromium from wastewaters has been studied and the optimal process conditions were determined. The reverse osmosis (RO) technique, the sea water high rejection (SWHR) and high rejection brackish water (AG, SE, and SG) membranes were used. The chromium rejection depended on membrane type, pH of the feed water and operating pressure. The removal of chromium was most effective when the feed water pH 3. The rejection efficiency of the membranes increased in the order AG > SWHR > SG > SE. RO method can be efficiently used (with >91% rejection) for the removal of chromium from wastewater of chromium coating processes.

  18. Chromium allergy and dermatitis: prevalence and main findings

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl;

    2015-01-01

    The history of chromium as an allergen goes back more than a century, and includesan interventional success with national legislation that led to significant changes inthe epidemiology of chromium allergy in construction workers. The 2015 EU Leather Regulation once again put a focus on chromium...... allergy, emphasizing that the investigation of chromium allergy is still far from complete. Our review article on chromium focuses on the allergen’s chemical properties, its potential exposure sources, and the allergen’s interaction with the skin, and also provides an overview of the regulations...

  19. Phyto-crystallization of palladium through reduction process using Cinnamom zeylanicum bark extract

    Energy Technology Data Exchange (ETDEWEB)

    Sathishkumar, M.; Sneha, K.; Kwak, In Seob; Mao, Juan [Environmental Biotechnology National Research Laboratory, School of Chemical Engineering, Research Institute of Industrial Technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Tripathy, S.J. [Nanoparticulate Materials Laboratory, Division of Advanced Materials Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Yun, Y.-S., E-mail: ysyun@chonbuk.ac.kr [Environmental Biotechnology National Research Laboratory, School of Chemical Engineering, Research Institute of Industrial Technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2009-11-15

    In this paper we studied the potential of nanocrystalline palladium particle production using Cinnamom zeylanicum bark extract (CBE) as the biomaterial for the first time. We studied the effects of biomaterial dosage, pH and temperature on nanoparticle formation; none of these factors had a major effect on the size and shape of the nanoparticles formed. Transmission electron microscopy (TEM) observations confirmed the synthesis of nano-sized palladium particles. More or less uniformly sized palladium nanoparticles were synthesized with an average size ranging from 15 to 20 nm. It was found that the zeta potential of these formed palladium nanoparticles was negative, and that it increased with an increase in pH. Energy dispersive X-ray (EDX) analysis results confirmed the significant presence of palladium. Of the palladium ions, 60% were reduced to a zero valent form by CBE. Terpenoids are believed to play an important role in palladium nanoparticle biosynthesis through the reduction of palladium ions. Currently, however, the exact mechanism for the synthesis of palladium nanoparticles is unclear. Our protocol for the phyto-synthesis of palladium nanoparticles under moderate pH and room temperature offers a new means to develop environmentally benign nanoparticles.

  20. Palladium catalyzed heck arylation of 2,3-dihydrofuran-effect of the palladium precursor.

    Science.gov (United States)

    Morel, Adam; Trzeciak, Anna M; Pernak, Juliusz

    2014-06-19

    Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba)3, Pd(acac)2, PdCl2(cod), [PdCl(allyl)]2, PdCl2(PhCN)2, PdCl2(PPh3)2) and ionic liquids (CILs) with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3) was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenzene were achieved for the [PdCl(allyl)]2 precursor. Formation of Pd(0) nanoparticles, representing the resting state of the catalyst, was evidenced by TEM.

  1. Palladium Catalyzed Heck Arylation of 2,3-Dihydrofuran—Effect of the Palladium Precursor

    Directory of Open Access Journals (Sweden)

    Adam Morel

    2014-06-01

    Full Text Available Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba3, Pd(acac2, PdCl2(cod, [PdCl(allyl]2, PdCl2(PhCN2, PdCl2(PPh32 and ionic liquids (CILs with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3 was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenzene were achieved for the [PdCl(allyl]2 precursor. Formation of Pd(0 nanoparticles, representing the resting state of the catalyst, was evidenced by TEM.

  2. Pharmacokinetic Modeling of Trivalent and Hexavalent Chromium Based on Ingestion and Inhalation of Soluble Chromium Compounds.

    Science.gov (United States)

    1991-12-01

    be largely Cr(III) although some Cr(VI) exposure probably also occurs. Stainless-steel welders are exposed to nickel as well as to chromium compounds...welders are equivocal with respect to involvement of chromium, particularly since nickel in some chemical forms is an established lung carcinogen (Stern...microglobulin (Lindberg and Vesterberg, 1983), retinol-binding protein (Franchini and Mutti , 1988), B-glucuronidase ( Mutti et al., 1979), and kidney brush border

  3. Synthesis of novel photochromic pyrans via palladium-mediated reactions

    NARCIS (Netherlands)

    Böttcher, Christoph; Zeyat, Gehad; Ahmed, Saleh A.; Irran, Elisabeth; Cordes, Thorben; Elsner, Cord; Zinth, Wolfgang; Rueck-Braun, Karola

    2009-01-01

    Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from a bromo-substituted naphthopyran and benzopyrans. A novel photoswitchable benzopyran-based ω-amino acid for Fmoc-based soli

  4. Direct acylation of aryl bromides with aldehydes by palladium catalysis.

    Science.gov (United States)

    Ruan, Jiwu; Saidi, Ourida; Iggo, Jonathan A; Xiao, Jianliang

    2008-08-13

    A new protocol for the direct acylation of aryl bromides with aldehydes is established. It appears to involve palladium-amine cooperative catalysis, affording synthetically important alkyl aryl ketones in moderate to excellent yields in a straightforward manner, and broadening the scope of metal-catalyzed coupling reactions.

  5. Exposure to nickel and palladium from dental appliances

    NARCIS (Netherlands)

    Ventura Da Cruz Rodrigues Milheiro, A.M.

    2015-01-01

    The application of a dental material into the oral cavity is not free of biological implications, as deterioration of the material will undoubtedly occur. The adverse health effects of palladium and nickel are well known and their immunologic cross-reactivity is well established. The aim of this the

  6. Biotemplated fabrication of size controlled palladium nanoparticle chains

    NARCIS (Netherlands)

    Zhou, Xingfei; Zheng, Lifei; Li, Rong; Li, Bin; Pillai, Saju; Xu, Peng; Zhang, Yi

    2012-01-01

    Metal nanoparticles exhibit unique size- and spatial organization-dependent physical and chemical properties, and have a wide range of applications in various areas including single electron devices, chemical catalysts and biomedicines. In this paper, chains of palladium nanoparticles were obtained

  7. Palladium-Catalyzed Carboxylation of Activated Vinylcyclopropanes with CO2.

    Science.gov (United States)

    Mita, Tsuyoshi; Tanaka, Hiroyuki; Higuchi, Yuki; Sato, Yoshihiro

    2016-06-01

    By using a palladium catalyst with ZnEt2, activated vinylcyclopropanes were successfully converted into the corresponding β,γ-unsaturated carboxylic acids in high yields under a CO2 atmosphere (1 atm). The intermediate in this reaction is thought to be a nucleophilic η(1)-allylethylpalladium species, which would be produced from π-allylpalladium and ZnEt2 (umpolung reactivity).

  8. Palladium-Catalyzed alpha-Arylation of Tetramic Acids

    DEFF Research Database (Denmark)

    Storgaard, Morten; Dorwald, F. Z.; Peschke, B.;

    2009-01-01

    A mild, racemization-free, palladium-Catalyzed alpha-arylation of tetramic acids (2,4-pyrrolidinediones) has been developed. Various amino acid-derived tetramic acids were cleanly arylated by treatment with 2 mol % of Pd(OAc)(2), 4 mol % of a sterically demanding biaryl phosphine, 2.3 equiv of K2CO...

  9. Hydrogen storage studies of palladium decorated nitrogen doped graphene nanoplatelets.

    Science.gov (United States)

    Vinayan, B P; Sethupathi, K; Ramaprabhu, S

    2012-08-01

    Hydrogen storage in materials is of significant importance in the present scenario of depleting conventional energy sources. Porous solids such as activated carbon or nanostructured carbon materials have promising future as hydrogen storage media. The hydrogen storage capacity in nanostructured carbon materials can be further enhanced by atomic hydrogen spillover from a supported catalyst. In the present work, the hydrogen storage properties of nitrogen doped graphene nanoplatelets (N-GNP) and palladium decorated nitrogen doped graphene nanoplatelets (Pd/N-GNP) have been investigated. The results show that hydrogen uptake capacity of nitrogen doped graphene nanoplatelets and palladium decorated nitrogen doped graphene nanoplatelets at pressure 32 bar and temperature 25 degrees C is 0.42 wt% and 1.25 wt% respectively. The dispersion of palladium nanoparticles increases the hydrogen storage capacity of nitrogen doped graphene nanoplatelets by 0.83 wt%. This may be due to high dispersion of palladium nanoparticles and strong adhesion between metal and graphene nanoplatelets over the surface of N-GNP, which enhances the spillover mechanism. Thus, an increase in the hydrogen spillover effect and the binding energy between metal nanoparticles and supporting material achieved by nitrogen doping has been observed to result in a higher hydrogen storage capacity of pristine GNP.

  10. Ultralow-power hydrogen sensing with single palladium nanowires

    NARCIS (Netherlands)

    Offermans, P.; Tong, H.D.; Rijn, C.J.M. van; Merken, P.; Brongersma, S.H.; Crego-Calama, M.

    2009-01-01

    Palladium nanowires were fabricated on silicon substrates using conventional microfabrication techniques. Sensors based on such nanowires show a reversible response to hydrogen concentrations as low as 27 ppm with response times varying from 5 s (H2 concentrations >20%) to 30 s (H2 concentrations <1

  11. Palladium-catalyzed silylation of aryl chlorides with hexamethyldisilane.

    Science.gov (United States)

    McNeill, Eric; Barder, Timothy E; Buchwald, Stephen L

    2007-09-13

    A method for the palladium-catalyzed silylation of aryl chlorides has been developed. The method affords desired product in good yield, is tolerant of a variety of functional groups, and provides access to a wide variety of aryltrimethylsilanes from commercially available aryl chlorides. Additionally, a one-pot procedure that converts aryl chlorides into aryl iodides has been developed.

  12. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    Science.gov (United States)

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  13. Catalytic removal of carbon monoxide over carbon supported palladium catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Avanish Kumar [Defence Research and Development Establishment, Jhansi Road, Gwalior-474002 (MP) (India); Saxena, Amit [Centre for Fire Explosive and Environmental Safety, Timarpur, Delhi-110054 (India); Shah, Dilip; Mahato, T.H. [Defence Research and Development Establishment, Jhansi Road, Gwalior-474002 (MP) (India); Singh, Beer, E-mail: beerbs5@rediffmail.com [Defence Research and Development Establishment, Jhansi Road, Gwalior-474002 (MP) (India); Shrivastava, A.R.; Gutch, P.K. [Defence Research and Development Establishment, Jhansi Road, Gwalior-474002 (MP) (India); Shinde, C.P. [School of Studies in Chemistry, Jiwaji University, Gwalior-474002 (MP) (India)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Carbon supported palladium (Pd/C) catalyst was prepared. Black-Right-Pointing-Pointer Catalytic removal of CO over Pd/C catalyst was studied under dynamic conditions. Black-Right-Pointing-Pointer Effects of Pd %, CO conc., humidity, GHSV and reaction environment were studied. - Abstract: Carbon supported palladium (Pd/C) catalyst was prepared by impregnation of palladium chloride using incipient wetness technique, which was followed by liquid phase reduction with formaldehyde. Thereafter, Pd/C catalyst was characterized using X-ray diffractometery, scanning electron microscopy, atomic absorption spectroscopy, thermo gravimetry, differential scanning calorimetry and surface characterization techniques. Catalytic removal of carbon monoxide (CO) over Pd/C catalyst was studied under dynamic conditions. Pd/C catalyst was found to be continuously converting CO to CO{sub 2} through the catalyzed reaction, i.e., CO + 1/2O{sub 2} {yields} CO{sub 2}. Pd/C catalyst provided excellent protection against CO. Effects of palladium wt%, CO concentration, humidity, space velocity and reaction environment were also studied on the breakthrough behavior of CO.

  14. Palladium nanoparticle-based surface acoustic wave hydrogen sensor.

    Science.gov (United States)

    Sil, Devika; Hines, Jacqueline; Udeoyo, Uduak; Borguet, Eric

    2015-03-18

    Palladium (Pd) nanoparticles (5-20 nm) are used as the sensing layer on surface acoustic wave (SAW) devices for detecting H2. The interaction with hydrogen modifies the conductivity of the Pd nanoparticle film, producing measurable changes in acoustic wave propagation, which allows for the detection of this explosive gas. The nanoparticle-based SAW sensor responds rapidly and reversibly at room temperature.

  15. Silver-palladium braze alloy recovered from masking materials

    Science.gov (United States)

    Cierniak, R.; Colman, G.; De Carlo, F.

    1966-01-01

    Method for recovering powdered silver-palladium braze alloy from an acrylic spray binder and rubber masking adhesive used in spray brazing is devised. The process involves agitation and dissolution of masking materials and recovery of suspended precious metal particles on a filter.

  16. Palladium catalyzed C3-arylation of 4-hydroxy-2-pyridones.

    Science.gov (United States)

    Anagnostaki, Elissavet E; Fotiadou, Anna D; Demertzidou, Vera; Zografos, Alexandros L

    2014-07-01

    The direct arylation of N-substituted-4-hydroxy-2-pyridones with aryl boronic acids has been achieved under palladium catalysis. The mild reaction conditions applied in this method and the use of a conventional catalytic system offer an attractive protocol for the efficient synthesis of a variety of 3-arylated products.

  17. Palladium-catalyzed enantioselective conjugate addition of arylboronic acids

    NARCIS (Netherlands)

    Gini, F; Hessen, B; Minnaard, AJ

    2005-01-01

    The first asymmetric palladium-catalyzed conjugate addition of arylboronic acids to alpha,beta-unsaturated aldehydes, ketones, and esters is described. For cyclic substrates, excellent chemo-, regio-, and enantioselectivities are achieved when a Pd(O2CCF3)(2)/DuPHOS catalyst is applied.

  18. Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

    Science.gov (United States)

    Qi, B.; Andrew, J. S.; Arnold, D. P.

    2017-03-01

    This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain ( 100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

  19. A Kinetic Model of Chromium in a Flame

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chromium has been identified as a carcinogenic metal.Incineration is the useful method for disposal of toxic chromium hazard waste and a chromium kinetic model in a flame is very important to study chromium oxidation.Chromium chemical kinetics over a range of temperatures of a hydrogen/air flame is proposed.Nine chromium compounds and fifty-eight reversible chemical reactions were considered The forward reaction rates are calculated based on the molecular collision approach for unknown ones and Arrhenius's Law for known ones.The backward reaction rates were calculated according to forward reaction rates, the equilibrium constants and chemical thermodynamics.It is verified by several equilibrium cases and is tested by a hydrogen/air diffusion flame.The results show that the kinetic model could be used in cases in which the chromium kinetics play an important role in a flame

  20. Extraction Of Chromium From Leather Chrome Shaving Dust.

    Directory of Open Access Journals (Sweden)

    Ashiqur Rahaman

    2015-08-01

    Full Text Available Leather processing involves transformation of putrescible animal hides and skin into non putrescible leather. Leather industry generates a huge amount of solid waste containing chromium. These solid wastes were disposed of through land filling which causes leaching out of in soil and water. Now a day increasing environmental legislations have encouraged tannery industry to develop a new technology. In this study we incinerated chrome shaving dust at 500oC to 7000C for chromium extraction. Various oxidizing acids with different concentration were used for chromium extraction. Extracted chromium was measured by Atomic Absorption Spectrometry. Recovery of chromium was in the range of 297 mgL to 222 mgL. Nitric acid extracted maximum amount of chromium while sulfuric acid extracted minimum amount of chromium.

  1. Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.

    Science.gov (United States)

    Mamais, Daniel; Noutsopoulos, Constantinos; Kavallari, Ioanna; Nyktari, Eleni; Kaldis, Apostolos; Panousi, Eleni; Nikitopoulos, George; Antoniou, Kornilia; Nasioka, Maria

    2016-06-01

    The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively.

  2. The effect of microstructure on the wear of cobalt-based alloys used in metal-on-metal hip implants.

    Science.gov (United States)

    Varano, R; Bobyn, J D; Medley, J B; Yue, S

    2006-02-01

    The influence of microstructure on the wear of cobalt-based alloys used in metal-on-metal hip implants was investigated in a boundary lubrication regime designed to represent the conditions that occurred some of the time in vivo. These cobalt-chromium-molybdenum alloys were either wrought, with a total carbon content of 0.05 or 0.23 wt %, cast with a solution-annealing procedure or simply as-cast but not solution annealed. Bars of these different alloy grades were subjected to various heat treatments to develop different microstructures. The wear was evaluated in a linear-tracking reciprocating pin-on-plate apparatus with a 25 per cent bovine serum lubricant. The wear was found to be strongly affected by the dissolved carbon content of the alloys and mostly independent of grain size or the carbide characteristics. The increased carbon in solid solution caused reductions in volumetric wear because carbon helped to stabilize a face-centred cubic crystal structure, thus limiting the amount of strain-induced transformation to a hexagonal close-packed crystal structure. Based on the observed surface twining in and around the contact zone and the potentially detrimental effect of the hexagonal close-packed phase, it was postulated that the wear of cobalt-based alloys in the present study was controlled by a deformation mechanism.

  3. The microstructure of chromium-tungsten steels

    Science.gov (United States)

    Klueh, R. L.; Maziasz, P. J.

    1989-03-01

    Chromium-tungsten steels are being developed to replace the Cr-Mo steels for fusion-reactor applications. Eight experimental steels were produced and examined by optical and electron microscopy. Chromium concentrations of 2.25, 5, 9 and 12 pct were used. Steels with these chromium compositions and with 2 pct W and 0.25 pct V were produced. To determine the effect of tungsten and vanadium, three other 2.25Cr steels were produced as follows: an alloy with 2 pct W and 0 pct V and alloys with 0 and 1 pct W and 0.25 pct V. A 9Cr steel containing 2 pct W, 0.25 pct V, and 0.07 pct Ta also was studied. For all alloys, carbon was maintained at 0.1 pct. Two pct tungsten was required in the 2.25Cr steels to produce 100 pct bainite (no polygonal ferrite). The 5Cr and 9Cr steels were 100 pct martensite, but the 12Cr steel contained about 25 pct delta-ferrite. Precipitate morphology and precipitate types varied, depending on the chromium content. For the 2.25Cr steels, M3C and M7C3 were the primary precipitates; for the 9Cr and 12Cr steels, M23C6 was the primary precipitate. The 5Cr steel contained M7C3 and M23C6. All of the steels with vanadium also contained MC.

  4. The electronic structure of antiferromagnetic chromium

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1981-01-01

    The author has used the local spin density formalism to perform self-consistent calculations of the electronic structure of chromium in the non-magnetic and commensurate antiferromagnetic phases, as a function of the lattice parameter. A change of a few per cent in the atomic radius brings...

  5. Design and performance of chromium mist generator

    Directory of Open Access Journals (Sweden)

    Tirgar Aram

    2006-01-01

    Full Text Available Chromium mist generator is an essential tool for conducting researches and making science-based recommendations to evaluate air pollution and its control systems. The purpose of this research was to design and construct a homogenous chromium mist generator and the study of some effective factors including sampling height and distances between samplers in side-by-side sampling on chromium mist sampling method. A mist generator was constructed, using a chromium electroplating bath in pilot scale. Concentration of CrO3 and sulfuric acid in plating solution was 125 g L-1 and 1.25 g L-1, respectively. In order to create permanent air sampling locations, a Plexiglas cylindrical chamber (75 cm height, 55 cm i.d was installed the bath overhead. Sixty holes were produced on the chamber in 3 rows (each 20. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and effective factors were studied via side-by-side air sampling method. So, 48 clusters of samples were collected on polyvinyl chloride (PVC filters housed in sampling cassettes. Cassettes were located in 35, 50, and 65 cm above the solution surface with less than 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed according to the NIOSH method 7600. According to the ANOVA test, no significant differences were observed between different sampling locations in side-by-side sampling (P=0.82 and between sampling heights and different samplers distances (P=0.86 and 0.86, respectively. However, there were notable differences between means of coefficient of variations (CV in various heights and distances. It is concluded that the most chromium mist homogeneity could be obtained at height 50 cm from the bath solution surface and samplers distance of < 7.5 cm.

  6. Cobalt-alloy implant debris induce HIF-1α hypoxia associated responses: a mechanism for metal-specific orthopedic implant failure.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1α is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1α, VEGF and TNF-α to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages and in vivo. HIF-1α in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1α with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell induced significantly elevated HIF-1α, VEGF, TNF-α and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1α was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n = 5 compared to failed Metal-on-Polymer articulating hip arthroplasties (n = 10. This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy, can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths.

  7. Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

    Directory of Open Access Journals (Sweden)

    Grzegorz Kowalski

    2014-01-01

    Full Text Available A study of polyaniline (PANI doping with various cobalt compounds, that is, cobalt(II chloride, cobalt(II acetate, and cobalt(II salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established.

  8. Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

    Science.gov (United States)

    Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

    2014-01-01

    A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established. PMID:24701183

  9. Cobalt: A vital element in the aircraft engine industry

    Science.gov (United States)

    Stephens, J. R.

    1981-01-01

    Recent trends in the United States consumption of cobalt indicate that superalloys for aircraft engine manufacture require increasing amounts of this strategic element. Superalloys consume a lion's share of total U.S. cobalt usage which was about 16 million pounds in 1980. In excess of 90 percent of the cobalt used in this country was imported, principally from the African countries of Zaire and Zambia. Early studies on the roles of cobalt as an alloying element in high temperature alloys concentrated on the simple Ni-Cr and Nimonic alloy series. The role of cobalt in current complex nickel base superalloys is not well defined and indeed, the need for the high concentration of cobalt in widely used nickel base superalloys is not firmly established. The current cobalt situation is reviewed as it applies to superalloys and the opportunities for research to reduce the consumption of cobalt in the aircraft engine industry are described.

  10. The electroanalytical detection of hydrazine: a comparison of the use of palladium nanoparticles supported on boron-doped diamond and palladium plated BDD microdisc array.

    Science.gov (United States)

    Batchelor-McAuley, Christopher; Banks, Craig E; Simm, Andrew O; Jones, Timothy G J; Compton, Richard G

    2006-01-01

    We show that both a random distribution of palladium nanoparticles supported on a BDD electrode or a palladium plated BDD microelectrode array can each provide a sensing platform for the electrocatalytic detection of hydrazine. The palladium nanoparticle modified electrode displays a sensitivity and limit of detection of 60 mA mol(-1) L and 2.6 microM respectively while the array has a sensitivity of 8 mA mol(-1) L with a detection limit of 1.8 microM. The beneficial cost implications of using palladium nano- or micro-particles in sensors compared to a palladium macroelectrode are evident. Interestingly the array of the nanoparticles shows similar sensitivity and limit of detection to the microelectrode array which probably indicates that the random distribution of the former leads to 'clumps' of nanoparticles that effectively act as microelectrodes.

  11. Aptamer selection for fishing of palladium ion using graphene oxide-adsorbed nanoparticles.

    Science.gov (United States)

    Cho, Yea Seul; Lee, Eun Jeong; Lee, Gwan-Ho; Hah, Sang Soo

    2015-12-01

    A new aptamer selection method using graphene oxide (GO)-adsorbed nanoparticles (GO-adsorbed NPs) was employed for specific fishing of palladium ion. High affinity ssDNA aptamers were isolated through 13 rounds of selection and the capacity of the selected DNA aptamers for palladium ion uptake was measured, clarifying that DNA01 exhibits the highest affinity to palladium ion with a dissociation constant (Kd) of 4.60±1.17 μM. In addition, binding ability of DNA01 to palladium ion was verified against other metal ions, such as Li(+), Cs(+), Mg(2+), and Pt(2+). Results of the present study suggest that future modification of DNA01 may improve palladium ion-binding ability, leading to economic recovery of palladium from water solution.

  12. Fexofenadine Suppresses Delayed-Type Hypersensitivity in the Murine Model of Palladium Allergy

    Science.gov (United States)

    Matsubara, Ryota; Kumagai, Kenichi; Shigematsu, Hiroaki; Kitaura, Kazutaka; Nakasone, Yasunari; Suzuki, Satsuki; Hamada, Yoshiki; Suzuki, Ryuji

    2017-01-01

    Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis. However, the precise mechanism of immune suppression in palladium allergy remains unknown. We investigated inhibition of the immune response in palladium allergic mice by administration of prednisolone as a glucocorticoid and fexofenadine hydrochloride as an antihistamine. Compared with glucocorticoids, fexofenadine hydrochloride significantly suppressed the number of T cells by interfering with the development of antigen-presenting cells from the sensitization phase. Our results suggest that antihistamine has a beneficial effect on the treatment of palladium allergy compared to glucocorticoids. PMID:28672829

  13. Fexofenadine Suppresses Delayed-Type Hypersensitivity in the Murine Model of Palladium Allergy

    Directory of Open Access Journals (Sweden)

    Ryota Matsubara

    2017-06-01

    Full Text Available Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis. However, the precise mechanism of immune suppression in palladium allergy remains unknown. We investigated inhibition of the immune response in palladium allergic mice by administration of prednisolone as a glucocorticoid and fexofenadine hydrochloride as an antihistamine. Compared with glucocorticoids, fexofenadine hydrochloride significantly suppressed the number of T cells by interfering with the development of antigen-presenting cells from the sensitization phase. Our results suggest that antihistamine has a beneficial effect on the treatment of palladium allergy compared to glucocorticoids.

  14. Characterization of the {beta}-phase of the palladium-hydrogen equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, K.J.

    1998-07-01

    The {beta}-phase of the P-C-T curves of the palladium-hydrogen system is encountered at high pressures of gaseous hydrogen and low temperatures of this system. The {beta}-phase is characterized by an increase in the concentration of hydrogen in the palladium lattice with an increase in pressure of the free hydrogen gas surrounding the palladium. The P-C-T curves in this study are determined by gravimetric measurements of the hydrided palladium sample to determine the amount of hydrogen within the palladium lattice. The amount of hydrogen is kept constant within the experimental system and the temperature is varied which changes the pressures. The objective of this experimental thesis is to accurately determine the P-C-T curves of palladium in the {beta}-phase region to pressures of 20,000 psia and medium to low temperature region of {minus}60 C to 100 C.

  15. Supported cobalt catalysts - preparation, characterization and reaction studies

    OpenAIRE

    Backman, Leif

    2009-01-01

    The aim of this work was to understand on the effect of thermal treatments, precursor and support on the interaction between the support and cobalt species, and further how the interaction affects the reducibility and dispersion of the catalyst. Silica and alumina supported cobalt catalysts were prepared, characterised and tested for catalytic activity. The catalysts were prepared by gas phase deposition techniques from cobalt acetylacetonate and cobalt carbonyl and by incipient wetness impre...

  16. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation

    OpenAIRE

    Majtan, Tomas; Frerman, Frank E.; Kraus, Jan P.

    2010-01-01

    Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound c...

  17. Synthesis of Samarium Cobalt Nanoblades

    Energy Technology Data Exchange (ETDEWEB)

    Darren M. Steele

    2010-08-25

    As new portable particle acceleration technologies become feasible the need for small high performance permanent magnets becomes critical. With particle accelerating cavities of a few microns, the photonic crystal fiber (PCF) candidate demands magnets of comparable size. To address this need, samarium cobalt (SmCo) nanoblades were attempted to be synthesized using the polyol process. Since it is preferable to have blades of 1-2 {micro}m in length, key parameters affecting size and morphology including method of stirring, reaction temperature, reaction time and addition of hydroxide were examined. Nanoparticles consisting of 70-200 nm spherical clusters with a 3-5 nm polyvinylpyrrolidone (PVP) coating were synthesized at 285 C and found to be ferromagnetic. Nanoblades of 25nm in length were observed at the surface of the nanoclusters and appeared to suggest agglomeration was occurring even with PVP employed. Morphology and size were characterized using a transmission electron microscope (TEM). Powder X-Ray Diffraction (XRD) analysis was conducted to determine composition but no supportive evidence for any particular SmCo phase has yet been observed.

  18. Recoverable Palladium(0) on Poly(vinylpyrrolidone) Catalyzed Ligand-free Suzuki Reaction in Water

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; LI Pin-Hua

    2006-01-01

    In the absence of any ligand, a recoverable palladium(O) on poly(vinylpyrrolidone) (PVP) catalyzed Suzuki reaction of aryl iodide and bromide with potassium aryltrifluoroborate was developed. The reaction conditions involved the use of water as the solvent, potassium carbonate as the base, and PVP supported palladium metal colloids as the catalyst. The palladium metal could be recovered and recycled for eight consecutive trials without significant loss of its activity.

  19. A Palladium-Binding Deltarhodopsin for Light-Activated Conversion of Protonic to Electronic Currents.

    Science.gov (United States)

    Soto-Rodríguez, Jessica; Hemmatian, Zahra; Josberger, Erik E; Rolandi, Marco; Baneyx, François

    2016-08-01

    Fusion of a palladium-binding peptide to an archaeal rhodopsin promotes intimate integration of the lipid-embedded membrane protein with a palladium hydride protonic contact. Devices fabricated with the palladium-binding deltarhodopsin enable light-activated conversion of protonic currents to electronic currents with on/off responses complete in seconds and a nearly tenfold increase in electrical signal relative to those made with the wild-type protein.

  20. Fundamental Laws of Structure and Form Changing of Palladium Loading with Hydrogen

    Institute of Scientific and Technical Information of China (English)

    GOLTSOVA M. V.; SPORTSMEN L. A.; ZHIROV G. I.

    2012-01-01

    There are reviewed some experimental results on metal-hydrogen and PdHx-hydrogen interaction.There is experimentally shown that penetration of hydrogen in palladium is accompanied with strong and micro structural effects,as well as grain shifts,etc.Moreover,the hydrogen saturation of palladium causes form-changing (bending) of palladium plate.These effects,undoubtedly,must be taken in account in technologies of low-temperature diffusion membrane apparatus exploitation.

  1. CHROMIUM INDUCED CYTOTOXICITY IN BLACKGRAM (VIGNA MUNGO L.

    Directory of Open Access Journals (Sweden)

    A. Chidambaram ، P. Sundaramoorthy ، A. Murugan ، K. Sankar Ganesh ، L. Baskaran

    2009-01-01

    Full Text Available Chromium is known to be highly toxic to biological systems. This study was designed to determine the mutagenic effects of different concentrations (0, 10, 25, 50, 100 and 200 mg/L of hexavalent chromium on root tip cells of blackgram (Vigna mungo L. Hepper. The blackgram seeds were equi-spacially arranged in sterilized petriplates lined with filter paper and they were treated with different concentrations of chromium solution. In germination studies, the morphological growth parameters such as germination percentage, root length, shoot length fresh weight and dry weight of blackgram seedlings were decreased with increasing dose of chromium concentrations. No germination of blackgram seeds was recorded at 300mg/l chromium concentration. Chromosome aberration assay was used to determine the mitotic indices and rate of chromosome aberration in blackgram root tip cells due to chromium treatment. The results showed that the mitotic indices were complicated due to different concentrations of chromium. However, the increase in chromium concentration has led to a gradual increase in the percentage of chromosomal aberration and mitotic index. The chromosome length, absolute chromosome length and average chromosome lengths were gradually found to decrease. There was no considerable change in 2n number of chromosome with the increase in chromium concentrations. It is concluded that the hexavalent chromium has significant mutagenic effect on the root tip cells of blackgram.

  2. Toward Financially Viable Phytoextraction and Production of Plant-Based Palladium Catalysts.

    Science.gov (United States)

    Harumain, Zakuan A S; Parker, Helen L; Muñoz García, Andrea; Austin, Michael J; McElroy, Con Robert; Hunt, Andrew J; Clark, James H; Meech, John A; Anderson, Christopher W N; Ciacci, Luca; Graedel, T E; Bruce, Neil C; Rylott, Elizabeth L

    2017-02-27

    Although a promising technique, phytoextraction has yet to see significant commercialization. Major limitations include metal uptake rates and subsequent processing costs. However, it has been shown that liquid-culture-grown Arabidopsis can take up and store palladium as nanoparticles. The processed plant biomass has catalytic activity comparable to that of commercially available catalysts, creating a product of higher value than extracted bulk metal. We demonstrate that the minimum level of palladium in Arabidopsis dried tissues for catalytic activity comparable to commercially available 3% palladium-on-carbon catalysts was achieved from dried plant biomass containing between 12 and 18 g·kg(-1) Pd. To advance this technology, species suitable for in-the-field application: mustard, miscanthus, and 16 willow species and cultivars, were tested. These species were able to grow, and take up, palladium from both synthetic and mine-sourced tailings. Although levels of palladium accumulation in field-suitable species are below that required for commercially available 3% palladium-on-carbon catalysts, this study both sets the target, and is a step toward, the development of field-suitable species that concentrate catalytically active levels of palladium. Life cycle assessment on the phytomining approaches described here indicates that the use of plants to accumulate palladium for industrial applications has the potential to decrease the overall environmental impacts associated with extracting palladium using present-day mining processes.

  3. Color Reaction of 2-(2-Quinolylazo)-5-Dimethylaminoaniline with Palladium and Its Application

    OpenAIRE

    SI, Yunsen; Hu,Qiufen; HUANG, Zhangjie; Yang, Guangyu; Yin,Jiayuan

    2014-01-01

    A new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA) was synthesized. A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with QADMAA was developed. In the presence of 0.5-2.5 mol L-1 of hydrochloric acid solution and cetyl trimethylammonium bromide medium QADMAA reacts with palladium to form a violet complex with a molar ratio of 1:2 (palladium to QADMAA). The molar absorptivity of the chela...

  4. Review on palladium-containing perovskites: synthesis, physico-chemical properties and applications in catalysis.

    Science.gov (United States)

    Essoumhi, Abdellatif; El Kazzouli, Saïd; Bousmina, Mosto

    2014-02-01

    This review reports on the recent advances in the synthesis and physico-chemical properties of palladium-containing perovskites. Initially, the perovskite structure is briefly reviewed, then palladium-containing perovskites synthesis and physico-chemical properties are detailed. The applications of palladium-containing perovskites in catalysis; namely, NO reduction, methane combustion, methanol as well as ethanol oxidation, are briefly highlighted. The involvement and the important contribution of palladium-containing perovskites in cross-coupling reactions, especially Suzuki-Miyaura, Sonogashira, Ulmann and Grignard, are discussed.

  5. Development and Making of New Jewellery Palladium Based Alloys at JSC "Krastsvetmet"

    Institute of Scientific and Technical Information of China (English)

    YEFIMOV V. N.; MAMONOV S. N.; SHULGIN D. R.; YELTSIN S. I.

    2012-01-01

    Complex of research and development work aimed at implementation of jewellery palladium based alloys technology has been carried out at JSC Krastsvetmet.A range of palladium alloys jewellery fabrication has been organized.Compositions of a number of jewellery palladium alloys grade 850,900,950 and 990 have been proposed,their production and application in jewellery manufacture has been organized.To produce palladium alloys induction melting in inert atmosphere and melt pouring into a copper mould has been used.The ingots heat treatment conditions,as well as semi-finished jewelry plastic deformation parameters have been determined.

  6. Separation of Hydrogen Using an Electroless Deposited Thin-Film Palladium-Ceramic Composite Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ilias, S.; King, F.G.; Fan, Ting-Fang; Roy, S. [North Carolina Agricultural and Technical State Univ., Greensboro, NC (United States). Dept. of Chemical Engineering

    1996-12-31

    The primary objective of this project was to prepare and characterize a hydrogen permselective palladium-ceramic composite membrane for high temperature gas separations and catalytic membrane reactors. Electroless plating method was used to deposit a thin palladium film on microporous ceramic substrate. The objective of this paper is to discuss the preparation and characterization of a thin-film palladium-ceramic composite membrane for selective separation of hydrogen at elevated temperatures and pressures. In this paper, we also present a model to describe the hydrogen transport through the palladium-ceramic composite membrane in a cocurrent flow configuration.

  7. Optical properties and surface morphology studies of palladium contacts on mercuric iodide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    George, M.A.; Azoulay, M.; Burger, A.; Biao, Y.; Silberman, E. [Fisk Univ., Nashville, TN (United States). Dept. of Physics; Nason, D. [EG and G Energy Measurements, Inc., Goleta, CA (United States). Santa Barbara Operations

    1993-05-01

    Palladium is chemically suitable for electric contacts on mercuric iodide detectors for photon and nuclear radiation detection, so the understanding of palladium contacts is important for fundamental and practical scientific purposes. A study has been conducted on the surface morphology of evaporated contacts using Atomic Force Microscopy (AFM) and optical transmission and reflection. Evaporated palladium coatings are typically nonuniform and may deposit selectively on mercuric iodide surface defects. Reflection measurements show that coating thickness and surface treatment affect intensity, position and shape of a reflected peak characteristic of the mercuric iodide structure. Results indicate that the band gap energy in the surface of the mercuric iodide is lowered by palladium contacts.

  8. Optical properties and surface morphology studies of palladium contacts on mercuric iodide single crystals

    Science.gov (United States)

    George, M. A.; Azoulay, M.; Burger, A.; Biao, Y.; Silberman, E.; Nason, D.

    1993-04-01

    Palladium is chemically suitable for electric contacts on mercuric iodide detectors for photon and nuclear radiation detection, so the understanding of palladium contacts is important for fundamental and practical scientific purposes. A study has been conducted on the surface morphology of evaporated contacts using atomic force microscopy (AFM) and optical transmission and reflection. Evaporated palladium coatings are typically nonuniform and may deposit selectively on mercuric iodide surface defects. Reflection measurements show that coating thickness and surface treatment affect intensity, position, and shape of a reflected peak characteristic of the mercuric iodide structure. Results indicate that the band gap energy in the surface of the mercuric iodide is lowered by palladium contacts.

  9. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung epithelial cells.

    Science.gov (United States)

    Xie, Hong; Smith, Leah J; Holmes, Amie L; Zheng, Tongzhang; Pierce Wise, John

    2016-05-01

    Cobalt is a toxic metal used in various industrial applications leading to adverse lung effects by inhalation. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells, especially normal lung epithelial cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in normal primary human lung epithelial cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble and particulate cobalt induced similar cytotoxicity while soluble cobalt was more genotoxic than particulate cobalt. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung epithelial cells.

  10. Electrochemical formation of holmium-cobalt alloys

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The electrochemical formation processes of holmium-cobalt alloys on cobalt cathode in molten HoC13-KC1 wereinvestigated by cyclic voltammetry and open current potential-time curve after potentiostatic electrolysis. The structure ofHo-Co alloys' films deposited on cobalt electrode by potentiostatic electrolysis was characterized by X-ray diffraction. Thestandard Gibbs free energies of formation for the intermetallic compounds of Ho and Co were determined. The diffusioncoefficient and diffusion activation energy of Ho atom in the alloy phase were calculated to be 10-10-10-11 cm2/s and 96.0kJ/mol, respectively, from the current-time curve at potential step.

  11. Total quality management of cobalt-60 sources

    Science.gov (United States)

    Malkoske, G. R.

    1999-06-01

    Total Quality Management of Cobalt-60 sources by a supplier requires a life cycle approach to source management. This covers various aspects, including design, manufacturing, installation, field inspection, source surveillance and return of cobalt-60 sources at the end of their useful life. The Total Quality Management approach demonstrates a strong industry commitment to the beneficial use of gamma technology for industrial irradiation applications in both developed nations and in those nations who are developing their infrastructure and techniques for the beneficial use of this technology. MDS Nordion continues to demonstrate its support and commitment to the industry by developing and implementing state-of-the-art standards for the safe use of cobalt-60 sources.

  12. Controlled cobalt doping in biogenic magnetite nanoparticles

    Science.gov (United States)

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

    2013-01-01

    Cobalt-doped magnetite (CoxFe3 −xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites. PMID:23594814

  13. Perfluorinated cobalt phthalocyanine effectively catalyzes water electrooxidation

    KAUST Repository

    Morlanes, Natalia Sanchez

    2014-12-08

    Efficient electrocatalysis of water oxidation under mild conditions at neutral pH was achieved by a fluorinated cobalt phthalocyanine immobilized on fluorine-doped tin oxide (FTO) surfaces with an onset potential at 1.7 V vs. RHE. Spectroscopic, electrochemical, and inhibition studies indicate that phthalocyanine molecular species are the operational active sites. Neither free cobalt ions nor heterogeneous cobalt oxide particles or films were observed. During long-term controlled-potential electrolysis at 2 V vs. RHE (phosphate buffer, pH 7), electrocatalytic water oxidation was sustained for at least 8 h (TON ≈ 1.0 × 105), producing about 4 μmol O2 h-1 cm-2 with a turnover frequency (TOF) of about 3.6 s-1 and no measurable catalyst degradation.

  14. Adlayers of palladium particles and their aggregates on porous polypropylene hollow fiber membranes as hydrogenization contractors/reactors

    NARCIS (Netherlands)

    Volkov, V.V.; Lebedeva, V.I.; Petrova, I.V.; Bobyl, A.V.; Konnikov, S.G.; Roldughin, V.I.; Erkel, J. van; Tereshchenko, G.F.

    2011-01-01

    Principal approaches for the preparation of catalytic membrane reactors based on polymer membranes containing palladium nanoparticles and for the description of their characteristics are presented. The method for the development of adlayers composed of palladium nanoparticles and their aggregates on

  15. Adlayers of palladium particles and their aggregates on porous polypropylene hollow fiber membranes as hydrogenization contractors/reactors

    NARCIS (Netherlands)

    Volkov, V.V.; Lebedeva, V.I.; Petrova, I.V.; Bobyl, A.V.; Konnikov, S.G.; Roldughin, V.I.; Erkel, J. van; Tereshchenko, G.F.

    2011-01-01

    Principal approaches for the preparation of catalytic membrane reactors based on polymer membranes containing palladium nanoparticles and for the description of their characteristics are presented. The method for the development of adlayers composed of palladium nanoparticles and their aggregates on

  16. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Mthunzi, P. [National Laser Centre, Council for Scientific and Industrial Research, 0001 Pretoria (South Africa); Muller, T.F.G. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Julies, B. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Ramponi, R. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa)

    2014-12-01

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr{sub 2}O{sub 3} layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr{sub 2}O{sub 3} layer. The α-Cr{sub 2}O{sub 3} layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%.

  17. Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather.

    Science.gov (United States)

    Dettmer, Aline; Nunes, Keila Guerra Pacheco; Gutterres, Mariliz; Marcílio, Nilson Romeu

    2010-04-15

    Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept.

  18. Cobalt and marine redox evolution

    Science.gov (United States)

    Swanner, Elizabeth D.; Planavsky, Noah J.; Lalonde, Stefan V.; Robbins, Leslie J.; Bekker, Andrey; Rouxel, Olivier J.; Saito, Mak A.; Kappler, Andreas; Mojzsis, Stephen J.; Konhauser, Kurt O.

    2014-03-01

    Cobalt (Co) is a bio-essential trace element and limiting nutrient in some regions of the modern oceans. It has been proposed that Co was more abundant in poorly ventilated Precambrian oceans based on the greater utilization of Co by anaerobic microbes relative to plants and animals. However, there are few empirical or theoretical constraints on the history of seawater Co concentrations. Herein, we present a survey of authigenic Co in marine sediments (iron formations, authigenic pyrite and bulk euxinic shales) with the goal of tracking changes in the marine Co reservoir throughout Earth's history. We further provide an overview of the modern marine Co cycle, which we use as a platform to evaluate how changes in the redox state of Earth's surface were likely to have affected marine Co concentrations. Based on sedimentary Co contents and our understanding of marine Co sources and sinks, we propose that from ca. 2.8 to 1.8 Ga the large volume of hydrothermal fluids circulating through abundant submarine ultramafic rocks along with a predominantly anoxic ocean with a low capacity for Co burial resulted in a large dissolved marine Co reservoir. We tentatively propose that there was a decrease in marine Co concentrations after ca. 1.8 Ga resulting from waning hydrothermal Co sources and the expansion of sulfide Co burial flux. Changes in the Co reservoir due to deep-water ventilation in the Neoproterozoic, if they occurred, are not resolvable with the current dataset. Rather, Co enrichments in Phanerozoic euxinic shales deposited during ocean anoxic events (OAE) indicate Co mobilization from expanded anoxic sediments and enhanced hydrothermal sources. A new record of marine Co concentrations provides a platform from which we can reevaluate the role that environmental Co concentrations played in shaping biological Co utilization throughout Earth's history.

  19. Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Partha P. Goswami

    2013-01-01

    Full Text Available Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques.

  20. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  1. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  2. Interactions of chromium with microorganisms and plants.

    Science.gov (United States)

    Cervantes, C; Campos-García, J; Devars, S; Gutiérrez-Corona, F; Loza-Tavera, H; Torres-Guzmán, J C; Moreno-Sánchez, R

    2001-05-01

    Chromium is a highly toxic non-essential metal for microorganisms and plants. Due to its widespread industrial use, chromium (Cr) has become a serious pollutant in diverse environmental settings. The hexavalent form of the metal, Cr(VI), is considered a more toxic species than the relatively innocuous and less mobile Cr(III) form. The presence of Cr in the environment has selected microbial and plant variants able to tolerate high levels of Cr compounds. The diverse Cr-resistance mechanisms displayed by microorganisms, and probably by plants, include biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux. Some of these systems have been proposed as potential biotechnological tools for the bioremediation of Cr pollution. In this review we summarize the interactions of bacteria, algae, fungi and plants with Cr and its compounds.

  3. A new cobalt oxide electrodeposit bath for solar absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Enrique [Departmento de IPH, Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana - Iztapalapa, Mexico D.F. (Mexico); Gonzalez, Ignacio [Departmento de Quimica, Area de Electroquimica, Universidad Autonoma Metropolitana - Iztapalapa, Mexico D.F. (Mexico); Viveros, Tomas [Departmento de IPH, Area de Ingenieria Quimica, Universidad Autonoma Metropolitana - Iztapalapa, Mexico D.F. (Mexico)

    1997-12-19

    A study was carried out in a Hull cell in order to optimize the deposition conditions of cobalt oxide (black cobalt) in an electrolytic bath, which uses cobalt nitrate for direct obtention of black cobalt. Thermal stability of the material was surveyed on several samples of black cobalt prepared on stainless-steel with a thickness of approximately of 2.5 {mu}m. It was found that the optical properties change, in respect to the initial values, with time of treatment until an equilibrium is reached. This equilibrium depends on the substrate and the temperature of the treatment used

  4. Effect of cobalt on the primary productivity of Spirulina platensis

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R.M.; Panigrahi, S.; Azeez, P.A.

    1987-10-01

    Cobalt, a micronutrient for biological organisms, is a metal of wide use. Main sources of Co to the environment are combustion of fossil fuels, smelters, cobalt processing facilities, sewage and industrial wastes. Atomic power plants and nuclear weapon detonations form an important source of radioisotopes of this metal to the environment. Cobalt has been included in the 14 toxic trace elements of critical importance from the point of view of environmental pollution and health hazards. Cobalt deficiency leads to diseases like stunted growth. At toxic level, Co inhibits heme biosynthesis and enzyme activities. The present study reports the effect of cobalt on biomass productivity of blue-green alga Spirulina platensis.

  5. Speciation and recovery of chromium from chromite ore processing residues.

    Science.gov (United States)

    Sreeram, K J; Ramasami, T

    2001-10-01

    The processing of chromite ore is associated with the generation of large quantities of solid wastes containing chromium, which have been disposed of as landfill for many years. The mobilization and operational speciation of chromium contained in soils contaminated with metal salts are important in terms of the environment. Several methods have been employed for the extraction and recovery of solid wastes. Chromium contained in contaminated soils and solid wastes can be categorized as exchangeable, oxidizable, carbonate-bound, reducible and residual. The results from this study indicate a need for efficient leaching methodologies in chromite ore processing plants to decrease the non-detrital fractions of chromium in the residue. Aggressive methodologies are required to recover chromium from the detrital fractions. The potential benefits of employing sodium peroxide for the complete recovery of chromium from chromite residue have been demonstrated, and the need to ensure the safety of the process has been emphasized.

  6. Effect of polyethylene glycol on electrochemically deposited trivalent chromium layers

    Institute of Scientific and Technical Information of China (English)

    Joo-Yul LEE; Man KIM; Sik-Chol KWON

    2009-01-01

    The structural characteristics of the trivalent chromium deposits and their interfacial behavior in the plating solution with and without polyethylene glycol molecules were observed by using various electrochemical methods such as cyclic voltammetry, open circuit potential transition, electrochemical impedance spectroscopy, scanning electron microscopy and X-ray photoelectron spectrometry. It is shown that the polyethylene glycol molecules make the reductive current density lower in the trivalent chromium plating system and promote a hydrogen evolution reaction through their adsorption on the electrode surface. And the trivalent chromium layer formed from the polyethylene glycol-containing solution has somewhat higher density of cracks on its surface and results in a lower film resistance, lower polarization resistance, and higher capacitance in a corrosive atmosphere. It is also revealed that the formation of chromium carbide layer is facilitated in the presence of polyethylene glycol, which means easier electrochemical codeposition of chromium and carbon, not single chromium deposition.

  7. Chromium Toxicity: Reductive Enzymes in Humans.

    Science.gov (United States)

    2007-11-02

    internal organs (e.g. lungs, liver, kidneys) [24,27,64], pulmonary fibrosis and chronic bronchitis [2], skin ulcers and allergic dermatitis [2], and...cross the skin [2] and are readily transported across cell membranes [18] via an anion carrier [6]. Cr compounds are also mutagenic [67], and the bulk of...reduced nicotinamide adenine dinucleotide phosphate-cytochrome P450 oxidoreductase- dependent chromium(VI) reduction. Analyst 120:935-938. 42. Miura, A

  8. Controlled immobilization of palladium nanoparticles in two different fluorinated polymeric aggregate cores and their application in catalysis

    DEFF Research Database (Denmark)

    Kijima, Tetsushi; Javakhishvili, Irakli; Jankova Atanasova, Katja

    2012-01-01

    ,3,4,5,6-pentafluorostyrene)-containing ABA-triblock copolymeric nanocomposites-immobilized palladium nanoparticles were prepared by the use of the corresponding block copolymers under similar conditions. TEM images showed that palladium nanoparticles can be immobilized outside the fluorinated cooligomeric nanocomposite...... cores; in contrast, palladium nanoparticles can be effectively immobilized inside these fluorinated ABA-triblock copolymeric nanocomposite cores. Thus, these two different fluorinated copolymers enabled the controlled immobilization of palladium nanoparticles in the fluorinated nanocomposite cores...

  9. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells.

    Science.gov (United States)

    Smith, Leah J; Holmes, Amie L; Kandpal, Sanjeev Kumar; Mason, Michael D; Zheng, Tongzhang; Wise, John Pierce

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity.

  10. Dimensionally Controlled Lithiation of Chromium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Fister, Tim T. [Argonne National Lab. (ANL), Argonne, IL (United States); Hu, Xianyi [Northwestern Univ., Evanston, IL (United States); Esbenshade, Jennifer [Univ. of Illinois, Urbana-Champaign, IL (United States); Chen, Xiao [Northwestern Univ., Evanston, IL (United States); Wu, Jinsong [Northwestern Univ., Evanston, IL (United States); Dravid, Vinayak [Northwestern Univ., Evanston, IL (United States); Bedzyk, Michael [Northwestern Univ., Evanston, IL (United States); Long, Brandon [Argonne National Lab. (ANL), Argonne, IL (United States); Gewirth, Andrew A. [Univ. of Illinois, Urbana-Champaign, IL (United States); Shi, Bing [Argonne National Lab. (ANL), Argonne, IL (United States); Schlepütz, Christian M. [Argonne National Lab. (ANL), Argonne, IL (United States); Fenter, Paul [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-12

    Oxide conversion reactions are an alternative approach for high capacity lithium ion batteries but are known to suffer from structural irreversibility associated with the phase separation and reconstitution of reduced metal species and Li2O. In particular, the morphology of the reduced metal species is thought to play a critical role in the electrochemical properties of a conversion material. Here we use a model electrode with alternating layers of chromium and chromium oxide to better understand and control these phase changes in real-time and at molecular length scales. Despite lacking crystallinity at the atomic scale, this superstructure is observed (with X-ray reflectivity, XR) to lithiate and delithiate in a purely one-dimensional manner, preserving the layered structure. The XR data show that the metal layers act as nucleation sites for the reduction of chromium in the conversion reaction. Irreversibility during delithiation is due to the formation of a ternary phase, LiCrO2, which can be further delithiated at higher potentials. The results reveal that the combination of confining lithiation to nanoscale sheets of Li2O and the availability of reaction sites in the metal layers in the layered structure is a strategy for improving the reversibility and mass transport properties that can be used in a wide range of conversion materials.

  11. Hydrogen sensor based on a graphene - palladium nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Ulrich, E-mail: ulrich.lange@chemie.uni-r.d [Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg (Germany); Hirsch, Thomas [Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg (Germany); Mirsky, Vladimir M. [Department of Nanobiotechnology, Lausitz University of Applied Sciences, 01968 Senftenberg (Germany); Wolfbeis, Otto S. [Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg (Germany)

    2011-04-01

    A composite material was prepared from graphene and palladium nanoparticles (PdNP) by layer-by-layer deposition on gold electrodes. The material was characterized by absorption spectroscopy, scanning electron microscopy, Raman spectroscopy and surface plasmon resonance. Cyclic voltammetry demonstrated the presence of electrocatalytic centers in the palladium decorated graphene. This material can serve as a sensor material for hydrogen at levels from 0.5 to 1% in synthetic air. Pure graphene is poorly sensitive to hydrogen, but incorporation of PdNPs increases its sensitivity by more than an order of magnitude. The effects of hydrogen, nitrogen dioxide and humidity were studied. Sensor regeneration is accelerated in humid air. The sensitivity of the nanocomposite depends on the number of bilayers of graphene-PdNPs.

  12. Palladium in cubic silicon carbide: Stability and kinetics

    Science.gov (United States)

    Roma, Guido

    2009-12-01

    Several technological applications of silicon carbide are concerned with the introduction of palladium impurities. Be it intentional or not, this may lead to the formation of silicides. Not only this process is not well understood, but the basic properties of palladium impurities in silicon carbide, such as solubility or diffusion mechanisms, are far from being known. Here the stability and kinetics of isolated Pd impurities in cubic silicon carbide are studied by first principles calculations in the framework of density functional theory. The preferential insertion sites, as well as the main migration mechanisms, are analyzed and presented here, together with the results for solution and migration energies. The early stages of nucleation are discussed based on the properties of isolated impurities and the smallest clusters.

  13. Hydrogen response of porous palladium nano-films

    Science.gov (United States)

    Gupta, D.; Barman, P. B.; Hazra, S. K.

    2015-08-01

    Palladium nanoparticles were synthesized by reducing sodium tetrachloropalladate at 100°C using Ethylene Glycol as reducing agent. The nanoparticles were characterized by TEM (Transmission Electron Microscopy), and optical absorption spectroscopy. The average particle size (cleaned glass substrates. The high porosity of these films, as revealed by Atomic Force Microscopy (AFM) studies, made these films suitable for hydrogen sensor applications. The resistance of the films, measured by making silver paste contacts on the porous surface, changed upon exposure to 1000 ppm hydrogen in nitrogen. Optimum sensor response was obtained at 50°C, beyond which it deteriorated. The total response comprising of initial rise and subsequent fall in resistance, is due to the formation of Pd-hydrides (whose resistivity is higher relative to Pd), and closure of interparticle gaps due to lattice expansion of palladium, respectively. A detailed analysis of the results based on the sensing mechanism has been discussed in the paper.

  14. Recovery of palladium using chemically modified cedar wood powder.

    Science.gov (United States)

    Parajuli, Durga; Hirota, Koichi

    2009-10-15

    Japanese cedar wood powder (CWP) was chemically modified to a tertiary-amine-type adsorbent and studied for the selective recovery of Pd(II) from various industrial waters. Batch adsorption tests performed from 0.1 M to 5 M HCl and HNO3 systems reveal stable performance with better results in HNO3 medium. The maximum loading capacity for Pd(II) was studied in HCl as well as in HNO3. A continuous-flow experiment taking a real industrial solution revealed the feasibility of using modified CWP for the selective uptake and preconcentration of traces of palladium contained in acidic effluents. In addition, stable adsorption performance even on long exposure to gamma-irradiation and selective recovery of palladium from simulated high-level liquid waste (HLW) are important outcomes of the study.

  15. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Møller, Per

    , a new coating has been designed to form an inhibiting effect on the surface by itself. In this way, it is desired that the release of any matter will be in low concentration. This design is based on silver combined with nobler palladium, both with catalytic properties. Due to the potential difference......The undesired microbial and biofilm adhesions on the surfaces of food industrial facilities, water supply systems and etc. are so called as “biofouling”. Biofouling can cause many undesirable effects. Until now for solving biofouling, there are few non-toxic inhibiting treatments. In this study...... between silver and palladium while contacting with an electrolyte, the surface can form numerous discrete anodic and cathodic areas, so that an inhibiting reaction can be formed. In this paper, a series of electrochemical and biological tests were conducted to study the properties of these surfaces...

  16. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Schroll, Casper

    2008-01-01

    Biofouling can cause many undesirable effects in industrial and medical settings. In this study, a new biofouling inhibiting Ag-Pd surface was designed to form an inhibiting effect by itself. This design was based on silver combined with nobler palladium, both with catalytic properties. Owing...... to the potential difference between silver and palladium while contacting with an electrolyte, the surface can form numerous discrete anodic and cathodic areas, so that an inhibiting reaction can occur. In this paper, a series of electrochemical and biological investigations were conducted to study the properties...... and biofouling inhibiting mechanism of these surfaces. In this study, the evidence is presented that the inhibiting effect can be caused by the electrochemical interactions and/or electric field between Pd and Ag/AgCl combined with an organic environment....

  17. Processes affecting the remediation of chromium-contaminated sites.

    OpenAIRE

    Palmer, C.D.; Wittbrodt, P R

    1991-01-01

    The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitat...

  18. Toxicity and bioactivity of cobalt nanoparticles on the monocytes.

    Science.gov (United States)

    Liu, Ya-ke; Ye, Jun; Han, Qing-lin; Tao, Ran; Liu, Fan; Wang, Wei

    2015-05-01

    To explore the toxicity and biological activity of cobalt nanoparticles on the osteoclasts. Analyze the relationship between cobalt nanoparticles and osteolysis. Monocyte-macrophages (RAW 264.7) was cultured in vitro, osteoclast-like cells were induced by lipopolysaccharides (LPS). After RAW 264.7 was induced for 24 h, Methyl Thiazolium Tetrazolium (MTT) biological toxicity test of osteoclast-like cell was preceded using Cobalt nanoparticles (set 4 concentrations: 10, 20, 50, 100 μM) and cobalt chloride (set 4 concentrations: 10, 20, 50, 100 μM) at 2, 4, 8, 24 and 48 h respectively. The relative expression of mRNA of CA II and Cat K after RAW 264.7 induction was determined by Q-PCR. mRNA relative expression of CA II, Cat K were reduced at multiple concentrations both cobalt nanoparticles and cobalt chloride, and was time and concentration dependent, cobalt nanoparticles are more significant than cobalt chloride group. But when the cobalt nanoparticles concentration is in 10-50 μM, the mRNA relative expression of CA II, Cat K increased. Cobalt nanoparticles have biological toxicity. At multiple concentrations, the differentiation and proliferation of osteoclasts was inhibited, but when the concentration of cobalt nanoparticles is in 10-50 μM, it has been strengthened. © 2015 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.

  19. New technology for comprehensive utilization of aluminum-chromium residue from chromium salts production

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; QI Tian-gui; JIANG Xin-min; ZHOU Qiu-sheng; LIU Gui-hua; PENG Zhi-hong; HAN Deng-lun; ZHANG Zhong-yuan; YANG Kun-shan

    2008-01-01

    Colloidal aluminum-chromium residue(ACR) was mass-produced in chromate production process, and the large energy consumption and high recovery cost existed in traditional methods of utilizing such ACR. To overcome those problems, a new comprehensive method was proposed to deal with the ACR, and was proven valid in industry. In the new process, the chromate was separated firstly from the colloidal ACR by ripening and washing with additives, by which more than 95% hexavalent chromium was recovered. The chromium-free aluminum residue(CFAR), after properly dispersed, was digested at 120-130 ℃ and more than 90% alumina can be recovered. And then the pregnant aluminate solution obtained from digestion was seeded to precipitate aluminum hydroxide. This new method can successfully recover both alumina and sodium chromate, and thus realize the comprehensive utilization of ACR from chromate industry.

  20. Cobalt reduction of NSSS valve hardfacings for ALARA

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joo Hak; Lee, Sang Sub [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-07-01

    This report informs NSSS designer that replacement of materials is one of the major means of ALARA implementation, and describes that NSSS valves with high-cobalt hardfacing are significant contributors to post-shutdown radiation fields caused by activation of cobalt-59 to cobalt-60. Generic procedures for implementing cobalt reduction programs for valves are presented. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. The nuclear safety issues involved with changing valve hardfacing materials are discussed. The common methods used to deposit hardfacing materials are described together with an explanation of the wear measurements. Wear resistance, corrosion resistance, friction coefficient, and mechanical properties of candidate hardfacing alloys are given. World-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The use of low-cobalt or cobalt-free alloys in other nuclear plant components is described. 17 figs., 38 tabs., 18 refs. (Author).

  1. Association between cobalt allergy and dermatitis caused by leather articles

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus

    2015-01-01

    BACKGROUND: Cobalt is a strong skin sensitizer and a prevalent contact allergen. Recent studies have recognized exposure to leather articles as a potential cause of cobalt allergy. OBJECTIVES: To examine the association between contact allergy to cobalt and a history of dermatitis resulting from ....... CONCLUSIONS: Our study suggests a positive association between cobalt allergy and a history of dermatitis caused by non-occupational exposure to leather articles.......BACKGROUND: Cobalt is a strong skin sensitizer and a prevalent contact allergen. Recent studies have recognized exposure to leather articles as a potential cause of cobalt allergy. OBJECTIVES: To examine the association between contact allergy to cobalt and a history of dermatitis resulting from...... as the most frequent exposure source causing dermatitis in the case group. Although the case group significantly more often reported non-occupational dermatitis caused by leather exposure (p

  2. Palladium- (and nickel-) catalyzed vinylation of aryl halides†

    OpenAIRE

    DENMARK, SCOTT E.; Butler, Christopher R.

    2008-01-01

    Functionalized styrenes are extremely useful building blocks for organic synthesis and for functional polymers. One of the most general syntheses of styrenes involves the combination of an aryl halide with a vinyl organometallic reagent under catalysis by palladium or nickel complexes. This Feature Article provides the first comprehensive summary of the vinylation methods currently available along with a critical comparison of the efficiency, cost and scope of the methods.

  3. Ozone Sensing Based on Palladium Decorated Carbon Nanotubes

    OpenAIRE

    2014-01-01

    Multiwall carbon nanotubes (MWCNTs) were easily and efficiently decorated with Pd nanoparticles through a vapor-phase impregnation-decomposition method starting from palladium acetylacetonates. The sensor device consisted on a film of sensitive material (MWCNTs-Pd) deposited by drop coating on platinum interdigitated electrodes on a SiO2 substrate. The sensor exhibited a resistance change to ozone (O3) with a response time of 60 s at different temperatures and the capability of detecting conc...

  4. Bio-palladium: from metal recovery to catalytic applications

    OpenAIRE

    2012-01-01

    Summary While precious metals are available to a very limited extent, there is an increasing demand to use them as catalyst. This is also true for palladium (Pd) catalysts and their sustainable recycling and production are required. Since Pd catalysts exist nowadays mostly under the form of nanoparticles, these particles need to be produced in an environment‐friendly way. Biological synthesis of Pd nanoparticles (‘bio‐Pd’) is an innovative method for both metal recovery and nanocatalyst synth...

  5. TCAP HYDROGEN ISOTOPE SEPARATION USING PALLADIUM AND INVERSE COLUMNS

    Energy Technology Data Exchange (ETDEWEB)

    Heung, L.; Sessions, H.; Xiao, S.

    2010-08-31

    The Thermal Cycling Absorption Process (TCAP) was further studied with a new configuration. Previous configuration used a palladium packed column and a plug flow reverser (PFR). This new configuration uses an inverse column to replace the PFR. The goal was to further improve performance. Both configurations were experimentally tested. The results showed that the new configuration increased the throughput by a factor of more than 2.

  6. Palladium-Catalyzed Synthesis of N-Aryl Carbamates

    Science.gov (United States)

    Vinogradova, Ekaterina V.; Park, Nathaniel H.; Fors, Brett P.; Buchwald, Stephen L.

    2013-01-01

    An efficient synthesis of aryl carbamates was achieved by introducing alcohols into the reaction of palladium-catalyzed cross-coupling of ArX (X = Cl, OTf) with sodium cyanate. The use of aryl triflates as electrophilic components in this transformation allowed for an expanded substrate scope for direct synthesis of aryl isocyanates. This methodology provides direct access to major carbamate protecting groups, S-thiocarbamates, and diisocyanate precursors to polyurethane materials. PMID:23441814

  7. In-situ synthesis of palladium nanoparticles-filled carbon nanotubes using arc-discharge in solution

    NARCIS (Netherlands)

    Bera, D; Kuiry, SC; McCutchen, M; Kruize, A; Heinrich, H; Meyyappan, M; Seal, S

    2004-01-01

    A unique, simple, inexpensive and one-step synthesis route of carbon nanotubes (CNT) supported palladium nanoparticles using a simplified arc-discharge in solution is reported. Palladium nanoparticles with 3 nm diameter were found to form during reduction of palladium tetra-chloro-square-planar

  8. In-situ synthesis of palladium nanoparticles-filled carbon nanotubes using arc-discharge in solution

    NARCIS (Netherlands)

    Bera, D; Kuiry, SC; McCutchen, M; Kruize, A; Heinrich, H; Meyyappan, M; Seal, S

    2004-01-01

    A unique, simple, inexpensive and one-step synthesis route of carbon nanotubes (CNT) supported palladium nanoparticles using a simplified arc-discharge in solution is reported. Palladium nanoparticles with 3 nm diameter were found to form during reduction of palladium tetra-chloro-square-planar comp

  9. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C

    1992-01-01

    Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting the simu......Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting...

  10. Influence of Chelating Agents on Chromium Fate in Sediment

    Institute of Scientific and Technical Information of China (English)

    WANGXIAOCHANG; SUNJINHE; 等

    1996-01-01

    A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment.The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the removal of Cr(Ⅲ)by sediment from solutions and the inhibiting effect was in the order:citric acid>tartaric acid>EDTA,Salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.

  11. Chromium recycling of tannery waste through microbial fermentation.

    Science.gov (United States)

    Katsifas, E A; Giannoutsou, E; Lambraki, M; Barla, M; Karagouni, A D

    2004-02-01

    An Aspergillus carbonarius isolate, selected from an established microbial culture collection, was used to study the biodegradation of chromium shavings in solid-state fermentation experiments. Approximately 97% liquefaction of the tannery waste was achieved and the liquid obtained from long-term experiments was used to recover chromium. The resulting alkaline chromium sulfate solution was useful in tanning procedures. A proteinaceous liquid was also obtained which has potential applications as a fertilizer or animal feed additive and has several other industrial uses. The A. carbonarius strain proved to be a very useful tool in tannery waste-treatment processes and chromium recovery in the tanning industries.

  12. Tribological Characteristics of Chromium-active Carbon Electroplated Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    GUKa-fi; HUAMeng; Yi-min

    2004-01-01

    A process of chromium electroplating using a standard bath with additives and active carbon particles was reported, and the tribological behaviors of the composite coatings using the pin-on-disk tester and the table wear tester were i nvestig(aed. Experimental results indicate that the electroplated chromium-active carbon composite coatings exhibited the low friction coefficient anti excellent anti-wear properties whets coffered with the normal chromium electroplated ones. The formation of active carbon particles within the chromium matrices can be explained by SEM analysis and the mechanis of wear resistance of the composite coatings were studied.

  13. Stabilization and solidification of chromium-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, C.A.; Thomson, B.M. [Univ. of New Mexico, Albuquerque, NM (United States). Civil Engineering Dept.; Conway, R. [Sandia National Labs., Albuquerque, NM (United States)

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.

  14. REINFORCEMENT OF NICKEL CHROMIUM ALLOYS WITH SAPPHIRE WHISKERS.

    Science.gov (United States)

    SAPPHIRE, COMPOSITE MATERIALS, CERAMIC FIBERS , CERAMIC FIBERS , TITANIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, HYDRIDES, ADDITIVES, CHROMIUM ALLOYS, FIBER METALLURGY, IRON COMPOUNDS, ENCAPSULATION, DENSITY, SURFACE TENSION.

  15. Method of trivalent chromium concentration determination by atomic spectrometry

    Science.gov (United States)

    Reheulishvili, Aleksandre N [Tbilisi, 0183, GE; Tsibakhashvili, Neli Ya [Tbilisi, 0101, GE

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  16. Colorimetric sensing of malathion using palladium-gold bimetallic nanozyme.

    Science.gov (United States)

    Singh, Shefali; Tripathi, Pranav; Kumar, Nitin; Nara, Seema

    2017-06-15

    In this work, a simple, sensitive and selective label free colorimetric assay using palladium-gold nanorod as nanozyme is reported for malathion detection. Study investigates the peroxidase potential of the nanozyme on colorimetric substrates and explores the effect of selected organophosphates on their enzyme mimetic activity. Palladium-gold nanozyme shows excellent peroxidase mimetic activity with O-phenylenediamine in the presence of hydrogen peroxide. Its Kinetic parameters Km and kcat are better than horseradish peroxidase which makes it a superior enzyme. Nanozyme is stable over a broad temperature range (4-70°C) and shows high peroxidase activity from 2 to 6pH. The peroxidase activity of nanozyme is selectively quenched with increasing concentration of malathion and is the principle of developed assay. Assay has a lowest detection limit of 60ng/ml and shows no cross-reaction with other analogous organophosphates or metal salts. Validation on tap water samples spiked with different concentrations of malathion shows good recovery in the range of 80-106%. Assay also displays good intra and inter-assay precision which lie in the range of 2.7-6.1% and 3.2-5.9% respectively. This study demonstrated the catalytic potential of palladium-gold nanorods, which can be employed as nanozyme for developing highly sensitive detection methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Nanometer-Size Effect on Hydrogen Sites in Palladium Lattice.

    Science.gov (United States)

    Akiba, Hiroshi; Kofu, Maiko; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Ikeda, Kazutaka; Otomo, Toshiya; Yamamuro, Osamu

    2016-08-17

    Nanometer-sized materials attract much attention because their physical and chemical properties are substantially different from those of bulk materials owing to their size and surface effects. In this work, neutron powder diffraction experiments on the nanoparticles of palladium hydride, which is the most popular metal hydride, have been performed at 300, 150, and 44 K to investigate the positions of the hydrogen atoms in the face-centered cubic (fcc) lattice of palladium. We used high-quality PdD0.363 nanocrystals with a diameter of 8.0 ± 0.9 nm. The Rietveld analysis revealed that 30% of D atoms are located at the tetrahedral (T) sites and 70% at the octahedral (O) sites. In contrast, only the O sites are occupied in bulk palladium hydride and in most fcc metal hydrides. The temperature dependence of the T-site occupancy suggested that the T-sites are occupied only in a limited part, probably in the subsurface region, of the nanoparticles. This is the first study to determine the hydrogen sites in metal nanoparticles.

  18. Hydrogen isotherms in palladium loaded carbon nanotubes and activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M. T.; Anson, A.; Lafuente, E.; Urriolabeitia, E.; Navarro, R.; Benito, A. M.; Maser, W. K.

    2005-07-01

    Session 5a In order to increase the hydrogen sorption capacity of carbon materials, a sample of single-wall carbon nanotubes (SWNTs) and the activated carbon MAXSORB have been loaded with palladium nanoparticles. While carbon materials adsorb hydrogen due to physical interactions, palladium can capture hydrogen into the bulk structure or chemically react to form hydrides. Experiental SWNTs have been synthesized in an electric arc reactor, using Ni and Y as catalysts in a 660 mbar He atmosphere. MAXSORB is a commercial activated carbon obtained from petroleum coke through a chemical treatment with KOH. Palladium has been deposited over the carbon support by means of a reflux method in a solution of an organometallic complex. Different samples have been prepared depending on the weight ratio (Carbon material / Pd) in the original reactants. The effectiveness of the deposition method has been examined by means of X-ray diffraction (XRD), induction coupled plasma spectrometry (ICPS) and transmission electron microscopy (TEM). The volumetric system Autosorb-1 from Quantachrome Instruments has been used to obtain the nitrogen adsorption isotherms at 77 K for all the materials. The hydrogen isotherms at 77 K and room temperature and up to 800 torr have also been obtained in the Autosorb-1. The BET specific surface area and the micropore volume have been calculated from the nitrogen adsorption data. High pressure hydrogen isotherms up to 90 bar have been carried out at room temperature in a VTI system provided with a Rubotherm microbalance. (Author)

  19. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles

    Science.gov (United States)

    Griessen, Ronald; Strohfeldt, Nikolai; Giessen, Harald

    2016-03-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and nanoparticles have recently been published. Although each article provides for the first time detailed data on specific aspects of hydrogen in nanoparticles, they individually do not contain enough information to draw firm conclusions about the involved mechanisms. Here, we show that the large body of data available so far in literature exhibits general patterns that lead to unambiguous conclusions about the processes involved in H absorption and desorption in Pd nanoparticles. On the basis of a remarkably robust scaling law for the hysteresis in absorption-desorption isotherms, we show that hydrogen absorption in palladium nanoparticles is consistent with a coherent interface model and is thus clearly different from bulk Pd behaviour. However, H desorption occurs fully coherently only for small nanoparticles (typically smaller than 50 nm) at temperatures sufficiently close to the critical temperature. For larger particles it is partially incoherent, as in bulk, where dilute α-PdHx and high concentration β-PdHx phases coexist.

  20. Recovery of hydrogen from impurities using a palladium membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Willms, R.S. [Los Alamos National Lab., NM (United States); Okuno, K. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan)

    1993-12-01

    One of the important steps in processing the exhaust from a fusion reactor is recovering tritium which is incorporated into molecules such as water and methane. One device which may prove to be very effective for this purpose is a palladium membrane reactor. This is a reactor which incorporates a Pd/Ag membrane in the reactor geometry. Reactions such as water gas shift, steam reforming and methane cracking can be carried out over the reactor catalyst, and the product hydrogen can be simultaneously removed from the reacting mixture. Because product is removed, greater than usual conversions can be obtained. In addition ultrapure hydrogen is produced, eliminating the need for an additional processing step. A palladium membrane reactor has been built and tested with three different catalysts. Initial results with a Ni-based catalyst show that it is very effective at promoting all three reactions listed above. Under the proper conditions, hydrogen recoveries approaching 100% have been observed. This study serves to experimentally validate the palladium membrane reactor as potentially important tool for fusion fuel processing.

  1. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles.

    Science.gov (United States)

    Griessen, Ronald; Strohfeldt, Nikolai; Giessen, Harald

    2016-03-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and nanoparticles have recently been published. Although each article provides for the first time detailed data on specific aspects of hydrogen in nanoparticles, they individually do not contain enough information to draw firm conclusions about the involved mechanisms. Here, we show that the large body of data available so far in literature exhibits general patterns that lead to unambiguous conclusions about the processes involved in H absorption and desorption in Pd nanoparticles. On the basis of a remarkably robust scaling law for the hysteresis in absorption-desorption isotherms, we show that hydrogen absorption in palladium nanoparticles is consistent with a coherent interface model and is thus clearly different from bulk Pd behaviour. However, H desorption occurs fully coherently only for small nanoparticles (typically smaller than 50 nm) at temperatures sufficiently close to the critical temperature. For larger particles it is partially incoherent, as in bulk, where dilute α-PdHx and high concentration β-PdHx phases coexist.

  2. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    Energy Technology Data Exchange (ETDEWEB)

    Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi, E-mail: ishiguro@rs.noda.tus.ac.jp [Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo, 125-8585 (Japan)

    2015-01-15

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

  3. Mechanochemical Preparation of Cobalt Nanoparticles through a Novel Intramolecular Reaction in Cobalt(II Complexes

    Directory of Open Access Journals (Sweden)

    Seyed Abolghasem Kahani

    2015-01-01

    Full Text Available A novel solid state reaction involving a series of cobalt(II hydrazine-azides has been used to prepare metallic cobalt nanoparticles. The reactions of [Co(N2H4(N32], [Co(N2H42(N32], and [Co(N2H4(N3Cl]·H2O via NaOH, KOH as reactants were carried out in the solid state. These complexes undergo an intramolecular two-electron oxidation-reduction reaction at room temperature, producing metallic cobalt nanoparticles (Co1–Co6. The aforementioned complexes contain cobalt(II that is an oxidizing agent and also hydrazine ligand as a reducing agent. Other products produced include sodium azide and ammonia gas. The cobalt metal nanoparticles were characterized using X-ray powder diffraction (XRD, scanning electron microscopy (SEM, and vibrating sample magnetometer (VSM. The synthesized cobalt nanoparticles have similar morphologies; however, their particle size distributions are different.

  4. A spot test for detection of cobalt release – early experience and findings

    DEFF Research Database (Denmark)

    Thyssen, Jacob P.; Menné, Torkil; Johansen, Jeanne D.

    2010-01-01

    Background: It is often difficult to establish clinical relevance of metal exposure in cobalt-allergic patients. Dermatologists and patients may incorrectly assume that many metallic items release cobalt at levels that may cause cobalt dermatitis. Cobalt-allergic patients may be unaware...... that they are exposed to cobalt from handling work items, causing hand dermatitis. Objectives: To present early findings with a newly developed cobalt spot test. Methods and Results: A cobalt spot test based on disodium-1-nitroso-2-naphthol-3,6-disulfonate was able to identify cobalt release at 8.3 ppm. The test may...... also be used as a gel test if combined with an agar preparation. We found no false-positive reactions when testing metals and alloys known not to contain cobalt. However, one cobalt-containing alloy, which elicited cobalt dermatitis in cobalt-allergic patients, was negative upon cobalt gel testing...

  5. Surface magnetism in iron, cobalt, and nickel

    DEFF Research Database (Denmark)

    Alde´n, M.; Mirbt, S.; Skriver, Hans Lomholt

    1992-01-01

    We have calculated magnetic moments, work functions, and surface energies for several of the most closely packed surfaces of iron, cobalt, and nickel by means of a spin-polarized Green’s-function technique based on the linear muffin-tin orbitals method within the tight-binding and atomic sphere...

  6. Spinel cobalt ferrite by complexometric synthesis

    NARCIS (Netherlands)

    Pham Duc Thang, P.D.T.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2005-01-01

    Magnetic fine particles of cobalt ferrite (CoFe2O4) have been synthesized using complexometric method in which ethylene diamine tetra acetic acid C10H16N2O8 (EDTA) acts as a complexing agent. The crystallographic structure, microstructure and magnetic properties of the synthesized powder were

  7. Evidence of Formation of Superdense Nonmagnetic Cobalt

    Science.gov (United States)

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

    2017-02-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure.

  8. Nano cobalt oxides for photocatalytic hydrogen production

    KAUST Repository

    Mangrulkar, Priti A.

    2012-07-01

    Nano structured metal oxides including TiO 2, Co 3O 4 and Fe 3O 4 have been synthesized and evaluated for their photocatalytic activity for hydrogen generation. The photocatalytic activity of nano cobalt oxide was then compared with two other nano structured metal oxides namely TiO 2 and Fe 3O 4. The synthesized nano cobalt oxide was characterized thoroughly with respect to EDX and TEM. The yield of hydrogen was observed to be 900, 2000 and 8275 mmol h -1 g -1 of photocatalyst for TiO 2, Co 3O 4 and Fe 3O 4 respectively under visible light. It was observed that the hydrogen yield in case of nano cobalt oxide was more than twice to that of TiO 2 and the hydrogen yield of nano Fe 3O 4 was nearly four times as compared to nano Co 3O 4. The influence of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  9. Cobalt Biogeochemistry in the South Atlantic: A Full-Depth Zonal Ocean Section of Total Dissolved Cobalt, and Development of a High Throughput Cobalt ICP-MS Method

    Science.gov (United States)

    Noble, A. E.; Saito, M. A.; Goepfert, T. J.

    2008-12-01

    This study presents the first high-resolution full-depth zonal section of total dissolved cobalt from a recent cruise transecting the South Atlantic Ocean along approximately 11S. This section demonstrates that current electrochemical analytical techniques are capable of producing the high precision and high resolution datasets for total dissolved cobalt expected to be generated as a part of the international GEOTRACES Program. The micronutritive role of cobalt may affect community structure in different regions of the oceans, a compelling reason to include cobalt in the trace element analyses planned for the GEOTRACES Program. This cobalt section reveals an advective source of cobalt from the African coast near Namibia, which we propose to be due to the Benguela Current interacting with reducing shelf sediments. These high concentrations of cobalt were also observed within the oxygen minimum zone that extends across much of the South Atlantic basin in this section, and are likely indicative of redox cycling of cobalt in the water column. Nutrient-like vertical structure of cobalt was observed in the surface waters across the majority of the basin due to biological utilization, and the expected hybrid-type trend is observed at depth, with scavenging of cobalt below the nutricline. Deepwater concentrations of cobalt were around 50pM across the basin below 3000m. Analysis of the shelf-life of refrigerated filtered samples stored without acidification for electrochemical cobalt analysis demonstrated that those samples which were collected specifically within oxygen minimum zones may underestimate cobalt if not analyzed within a few weeks of collection. These results motivate our on-going development of a method to measure cobalt in acidified samples via inductively coupled plasma mass spectrometry (ICP-MS). The benefit of this technique would be twofold: acidification would extend the shelf-life of the samples significantly, and samples would be preserved identically

  10. A spot test for detection of cobalt release - early experience and findings

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Menné, Torkil; Johansen, Jeanne D

    2010-01-01

    It is often difficult to establish clinical relevance of metal exposure in cobalt-allergic patients. Dermatologists and patients may incorrectly assume that many metallic items release cobalt at levels that may cause cobalt dermatitis. Cobalt-allergic patients may be unaware that they are exposed...... to cobalt from handling work items, causing hand dermatitis....

  11. Nafion-Teflon bimembrane-supported palladium catalysts for Suzuki coupling reactions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nafion-Teflon bimembrane was used as an efficient support for the preparation and application of heterogeneous palladium catalysts. The supported palladium catalysts exhibit high activity and stability in the Suzuki cross-coupling of aryl bromides with arylboronic acids to afford the corresponding biaryls in good to excellent yields, and can be readily recovered and reused several times without significant loss of activity.

  12. Synthesis of Dichloride-Diphenylacetonitrile Palladium and Metal-Polymer Composite Based on Uhmwpe

    Directory of Open Access Journals (Sweden)

    A. M. Nemeryuk

    2016-05-01

    Full Text Available New complex of Pd (II with phenylacetonitrile, suitable for use as a precursor of palladium nano particles in the composition of metal-based composite UHMWPE was obtained. The thermodynamic characteristics of metal-polymer composite, found the effect of nano particles of palladium in the crystallization processes in UHMWPE and other characteristics of the material.

  13. Structural and chemical characterisation of titanium deuteride films covered by nanoscale evaporated palladium layers

    NARCIS (Netherlands)

    Lisowski, W.; Keim, E.G.; Berg, van den A.H.J.; Smithers, M.A.

    2006-01-01

    Thin titanium deuteride (TiDy) films, covered by an ultra-thin palladium layer, have been compared with the corresponding titanium and palladium films using a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The TiD

  14. N-Heterocyclic Carbene-Palladium Complex Catalyzed Oxidative Carbonylation of Amines to Ureas

    Institute of Scientific and Technical Information of China (English)

    ZHENG,Shu-Zhan; PENG,Xin-Gao; LIU,Jian-Ming; SUN,Wei; XIA,Chun-Gu

    2007-01-01

    Palladium carbene shows high efficiency without any promoter on oxidative carbonylation of amines to ureas and a new type of palladium carbene complex containing both an aniline and an NHC ligands was found to be the active species for the reaction.

  15. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Leah J.; Holmes, Amie L. [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Kandpal, Sanjeev Kumar; Mason, Michael D. [Department of Chemical and Biological Engineering, University of Maine, Orono, ME (United States); Zheng, Tongzhang [Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT (United States); Wise, John Pierce, E-mail: John.Wise@usm.maine.edu [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States)

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity. - Highlights: • Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells. • Soluble cobalt induces more cytotoxicity compared to particulate cobalt. • Soluble and particulate cobalt induce similar levels of genotoxicity. • Particle-cell contact is required for particulate cobalt-induced toxicity.

  16. Adherence of Candida albicans in cobalto- chromium and titanium alloys, with different sandpapering

    Directory of Open Access Journals (Sweden)

    Sidnei MARCACCI

    2008-04-01

    Full Text Available Introduction: The capacity of Candida albicans adherence is one ofits main factors of virulence. Surfaces of different materials canpropitiate conditions for higher or lower adherence and greater virulence of the microorganisms. Objective: Evaluate the adherence of Candida albicans in cobalto-chromium and titanium alloys, with different sandpapering. Material and methods: Twenty-four cylindrical samples have been constructed, 12 of titanium and 12 of cobalt-chromium, divided in 4 groups of six. All have been polished in the habitual form by the same technician. Samples have been sandpapered at about high rotation for 15 seconds each sandpaper, on all its surface. A group of each metal was sandpapered only with sandpaper for metal number 80. The two other groups have been sandpapered in agreement with the sequence (decreasing granulation: 80, 150 and 220. Samples have been sterilized and located in plates of cells culture. In each well of the plate was added standardized amount of Sabouraud broth and suspension containing 106 cells per milliliter of C. albicans (ATCC 18804. After incubation, the number of adhered cells per mm2 was obtained by the method of sowing in plate of Petri. The obtained values have been tabulated and submitted to the tests of ANOVA and Tukey,with level of significance of 5%. Results: There was statistical difference for the granulation of sandpapers, what not occurred when considering metals.Conclusion: The bigger the final granulation of sandpaper, the greater the adherence and the type of metal did not influence in the result.

  17. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qinhua [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I2, ICl, PhSeCl, PhSCl and p-O2NC6H4SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement

  18. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    Energy Technology Data Exchange (ETDEWEB)

    Qinhua Huang

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I{sub 2}, ICl, PhSeCl, PhSCl and p-O{sub 2}NC{sub 6}H{sub 4}SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that

  19. 多组分废催化剂中钯的分离工艺研究进展%Research development on the separation of Palladium from multicomponent waste catalyst

    Institute of Scientific and Technical Information of China (English)

    闫江梅; 董庆; 张之翔

    2014-01-01

    简述了废催化剂中钯分离回收的基本过程和方法,指出多组分废钯催化剂具有很高的回收价值,但存在组分多、分离困难的问题。对于多组分废钯催化剂中钯与贵金属金、银、铂、铑等,以及与非贵金属铜、钴、镍、铁等的分离技术分别进行了简要介绍与评价。结果表明,化学沉淀法、溶剂萃取法、还原法、置换法是目前多组分废钯催化剂常用的回收方法。其中化学沉淀法是使用最多的方法,但存在回收周期长、复杂、成本较高的问题,而溶剂萃取法具有分离效果好、过程简单的优点,成为最具发展前景的方法。因此选择性高、无污染并适合大规模工业化的萃取新工艺成为未来的发展方向。%This paper is aimed to briefly introduce basic process and method for the separation and recovery of palladium from waste catalyst,to point out that the multicomponent spent palladium catalysts have high recovery value,but there are so many components that its separation is very difficult. For multicomponent spent palladium catalyst,the separation techniques of palladium from precious metals gold,silver,platinum,rhodium,etc.,as well as from non-precious metals copper, cobalt,nickel,iron and other are briefly described and evaluated. The results show that chemical precipitation,solvent extraction,reduction,and displacement are commonly used methods for recycling multicomponent spent palladium catalyst. The chemical precipitation method is the most used method, but limited by long recycling cycle,complex process,and high cost;and solvent extraction method has good separation effect and simple process,becoming the most promising method. Therefore,a new extraction technology with high selectivity,pollution free and suitable for large-scale industrialization shall be focused in future development.

  20. Preventive role of palladium-103 radioactive stent on in-stent restenosis in rabbit iliac arteries

    Institute of Scientific and Technical Information of China (English)

    LUO Quan-Yong; CHEN Li-Bo; YUAN Zhi-Bin; LU Han-Kui; ZHU Rui-Sen

    2005-01-01

    The abilility of γ-emitting palladium-103 stent implantation to inhibit in-stent restenosis in rabbit iliac arteries was investigated. Quantitative histomorphometry of the stented iliac segments 28 days after the implantation indicated that palladium-103 stents made a significant reduction in neointimal area and percent area stenosis compared with the nonradioactive stents. Lumen area in the palladium-103 stents treatment group was larger than the control group. However, the reduction of neointima formation by palladium-103 stents implantation was in a non-dose-dependent fashion. Low ionizing radiation doses via γ-emitting palladiurn-103 stent are effective in preventing neointimal hyperplasia in iliac arteries of rabbits. Palladium-103 stents can be employed as a possible novel means to prevent in-stent restenosis.

  1. Extraction of gold, palladium, and platinum from acidic media with cyclic sulfoxide derivative

    Institute of Scientific and Technical Information of China (English)

    Songping Wu; Guobang Gu

    2007-01-01

    The extraction of gold (Ⅲ), palladium (Ⅱ), and platinum (Ⅳ) from the acidic media with the cyclic sulfoxide derivative of a-dodecyl-tetrahydrothiophene 1-oxide (dtmso) was investigated. Gold (Ⅲ), palladium (Ⅱ), and platinum (Ⅳ) could be separated from the acidic media with suitable sulfoxide concentration and acidity. The extraction reaction of gold (Ⅲ), palladium (Ⅱ) or platinum (Ⅳ) is exothermic when dtmso is used as an extracting reagent. The coordination number was studied by the slope method. The results indicate that, in high acidity, the dtmso coordination number for extracting gold (Ⅲ) or palladium (Ⅱ) is 3, and that for platinum (Ⅳ) is 2. UV and FT-IR spectra were used to analyze the structure of the complex. Gold (Ⅲ) is coordinated with the oxygen atom in S=O group in dtmso, and palladium (Ⅱ) or platinum (Ⅳ) is coordinated with the sulfur atom in S=O group in dtmso.

  2. Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

    Institute of Scientific and Technical Information of China (English)

    Nghia T. BUI; Trung B. DANG; Ha V. LE; Nam T. S. PHAN

    2011-01-01

    A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g.The catalyst was characterized using X-ray diffraction,scanning electron microscopy,transmission electron microscopy,vibrating sample magnetometry,thermogravimetric analysis,Fourier transform infrared,atomic absorption spectrophotometry,and nitrogen adsorption.The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid.The recovery of catalyst was simply by magnetic decantation in the presence of a magnet.The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity.No leaching of active palladium species into the reaction solution was detected.

  3. Palladium-Mediated Surface-Initiated Kumada Catalyst Polycondensation: A Facile Route Towards Oriented Conjugated Polymers.

    Science.gov (United States)

    Huddleston, N Eric; Sontag, S Kyle; Bilbrey, Jenna A; Sheppard, Gareth R; Locklin, Jason

    2012-12-21

    Palladium-mediated surface-initiated Kumada catalyst transfer polycondensation is used to generate poly(3-methyl thiophene) films with controlled thickness up to 100 nm. The palladium initiator density is measured using cyclic voltammetry and a ferrocene-capping agent, where the surface density is found to be 55% (1.1 × 10(14) molecules per cm(2)). UV-Vis spectroscopy and AFM show increased aggregation in palladium-initiated films due to the higher grafting density of palladium initiators on the surface. The anisotropy of the P3MT films is determined using polarized UV-Vis spectroscopy, which indicates a degree of orientation perpendicular to the substrate. Evidence that palladium can maintain π-complexation even at elevated temperatures, is also shown through the exclusive intramolecular coupling of both a phenyl and thiophene-based magnesium bromide with different dihaloarenes.

  4. Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

    Institute of Scientific and Technical Information of China (English)

    吴玉程; 吴侠; 李广海; 张立德

    2003-01-01

    In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica,the silica was prepared by sol-gel technique,leading to an amorphous solid with mesoporosity,and the pore size distribution is narrow,centered at 3-5 nm.The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen.The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination,resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature.The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

  5. The influence of ethylenediamine tetra acetic acid (EDTA) on the transformation and solubility of metallic palladium and palladium(II) oxide in the environment.

    Science.gov (United States)

    Zereini, Fathi; Wiseman, Clare L S; Vang, My; Albers, Peter; Schneider, Wolfgang; Schindl, Roland; Leopold, Kerstin

    2015-05-01

    The environmental occurrence of elevated concentrations of platinum (Pt), palladium (Pd) and rhodium (Rh) from automotive catalytic converters has been well-documented. Limited information exists regarding their chemical behavior post-emission, however, especially in the presence of commonly occurring complexing agents. The purpose of this study is to examine the influence of ethylenediamine tetra acetic acid (EDTA) on the possible environmental transformation and solubility of Pd by conducting batch experiments using metallic palladium (Pd black) and palladium(ii) oxide (PdO). Changes in the particle surface chemistry of treated samples were analyzed using X-ray Photoelectron Spectroscopy (XPS) and Transition Electron Microscopy/Energy Dispersive X-ray Spectrometry (TEM/EDX) techniques. Metallic palladium was partially transformed into PdOx (x environmental immobility of Pd, small amounts of this element emitted in metallic form are likely to be soluble in the presence of complexing agents such as EDTA.

  6. Electrochemical dechlorination of chloroform in neutral aqueous solution on palladium/foam-nickel and palladium/polymeric pyrrole film/foam-nickel electrodes

    Institute of Scientific and Technical Information of China (English)

    SUN Zhirong; LI Baohua; HU Xiang; SHI Min; HOU Qingnan; PENG Yongzhen

    2008-01-01

    Electrochemical dechlonnafion of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature.Palladium/foam-nickel (Pd/foam-Ni) and palladium/polymeric pyrrole film/foam-nickel (Pd/PPy/foam-Ni)composite electrodes which provided catalytic surface for reductive dechiorination of chloroform in aqueous solution were prepared using an electrodepositing method.Scanning electron microscope (SEM) micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode.The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 rain,which is much higher than that of Pd/foam-Ni electrode.

  7. Femtosecond laser surface structuring and oxidation of chromium thin coatings: black chromium.

    CSIR Research Space (South Africa)

    Kotsedi, L

    2014-12-01

    Full Text Available Applied Surface Science 321 (2014) 560–565 Femtosecond laser surface structuring and oxidation of chromiumthin coatings: Black chromium L Kotsedi, (a,b), Z.Y. Nuru, (a,b), P. Mthunzi (c), T.F.G. Muller(d), S.M. Eaton (e), B. Julies(d), E. Manikandan (a...

  8. Diffusion of hexavalent chromium in chromium-containing slag as affected by microbial detoxification.

    Science.gov (United States)

    Wang, Yunyan; Yang, Zhihui; Chai, Liyuan; Zhao, Kun

    2009-09-30

    An electrochemical method was used to determine the diffusion coefficient of chromium(VI) in chromium-containing slag. A slag plate was prepared from the original slag or the detoxified slag by Achromobacter sp. CH-1. The results revealed that the apparent diffusion coefficient of Cr(VI) was 4.4 x 10(-9)m(2)s(-1) in original slag and 2.62 x 10(-8)m(2)s(-1) in detoxified slag. The results implied that detoxification of chromium-containing slag by Achromobacter sp. CH-1 could enhance Cr(VI) release. Meanwhile, the results of laboratory experiment showed that the residual total Cr(VI) in slag decreased from an initial value of 6.8 mg g(-1) to 0.338 mg g(-1) at the end of the detoxification process. The Cr(VI) released from slag was also reduced by Achromobacter sp. CH-1 strain since water soluble Cr(VI) in the leachate was not detected after 4 days. Therefore, Achromobacter sp. CH-1 has potential application for the bio-detoxification of chromium-containing slag.

  9. Ultra low nanowear in novel chromium/amorphous chromium carbide nanocomposite films

    Science.gov (United States)

    Yate, Luis; Martínez-de-Olcoz, Leyre; Esteve, Joan; Lousa, Arturo

    2017-10-01

    In this work, we report the first observation of novel nanocomposite thin films consisting of nanocrystalline chromium embedded in an amorphous chromium carbide matrix (nc-Cr/a-CrC) with relatively high hardness (∼22,3 GPa) and ultra low nanowear. The films were deposited onto silicon substrates using a magnetic filtered cathodic arc deposition system at various negative bias voltages, from 50 to 450 V. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) suggested the co-existence of chromium and chromium carbide phases, while high resolution transmission electron microscopy (HRTEM) confirmed the presence of the nc-Cr/a-CrC structure. The friction coefficient measured with the ball-on disk technique and the nanowear results showed a strong correlation between the macro and nano-tribological properties of the samples. These novel nanocomposite films show promising properties as solid lubricant and wear resistant coatings with relatively high hardness, low friction coefficient and ultra low nanowear.

  10. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

    Energy Technology Data Exchange (ETDEWEB)

    McCabe, D; Jeff Pike, J; Bill Wilmarth, B

    2007-04-25

    A workshop was held on January 23-24, 2007 to discuss the status of processes to leach constituents from High Level Waste (HLW) sludges at the Hanford and Savannah River Sites. The objective of the workshop was to examine the needs and requirements for the HLW flowsheet for each site, discuss the status of knowledge of the leaching processes, communicate the research plans, and identify opportunities for synergy to address knowledge gaps. The purpose of leaching of non-radioactive constituents from the sludge waste is to reduce the burden of material that must be vitrified in the HLW melter systems, resulting in reduced HLW glass waste volume, reduced disposal costs, shorter process schedules, and higher facility throughput rates. The leaching process is estimated to reduce the operating life cycle of SRS by seven years and decrease the number of HLW canisters to be disposed in the Repository by 1000 [Gillam et al., 2006]. Comparably at Hanford, the aluminum and chromium leaching processes are estimated to reduce the operating life cycle of the Waste Treatment Plant by 20 years and decrease the number of canisters to the Repository by 15,000-30,000 [Gilbert, 2007]. These leaching processes will save the Department of Energy (DOE) billions of dollars in clean up and disposal costs. The primary constituents targeted for removal by leaching are aluminum and chromium. It is desirable to have some aluminum in glass to improve its durability; however, too much aluminum can increase the sludge viscosity, glass viscosity, and reduce overall process throughput. Chromium leaching is necessary to prevent formation of crystalline compounds in the glass, but is only needed at Hanford because of differences in the sludge waste chemistry at the two sites. Improving glass formulations to increase tolerance of aluminum and chromium is another approach to decrease HLW glass volume. It is likely that an optimum condition can be found by both performing leaching and improving

  11. Safety, absorption, and antioxidant effects of chromium histidine

    Science.gov (United States)

    Supplemental chromium has been shown to be involved in the alleviation of the metabolic syndrome, glucose intolerance, polycystic ovary syndrome, depression, excess body fat, and gestational, steroid-induced, and type 2 diabetes. Chromium amino acid complexes that contained histidine displayed cons...

  12. Mechanisms of bacterial resistance to chromium compounds.

    Science.gov (United States)

    Ramírez-Díaz, Martha I; Díaz-Pérez, César; Vargas, Eréndira; Riveros-Rosas, Héctor; Campos-García, Jesús; Cervantes, Carlos

    2008-06-01

    Chromium is a non-essential and well-known toxic metal for microorganisms and plants. The widespread industrial use of this heavy metal has caused it to be considered as a serious environmental pollutant. Chromium exists in nature as two main species, the trivalent form, Cr(III), which is relatively innocuous, and the hexavalent form, Cr(VI), considered a more toxic species. At the intracellular level, however, Cr(III) seems to be responsible for most toxic effects of chromium. Cr(VI) is usually present as the oxyanion chromate. Inhibition of sulfate membrane transport and oxidative damage to biomolecules are associated with the toxic effects of chromate in bacteria. Several bacterial mechanisms of resistance to chromate have been reported. The best characterized mechanisms comprise efflux of chromate ions from the cell cytoplasm and reduction of Cr(VI) to Cr(III). Chromate efflux by the ChrA transporter has been established in Pseudomonas aeruginosa and Cupriavidus metallidurans (formerly Alcaligenes eutrophus) and consists of an energy-dependent process driven by the membrane potential. The CHR protein family, which includes putative ChrA orthologs, currently contains about 135 sequences from all three domains of life. Chromate reduction is carried out by chromate reductases from diverse bacterial species generating Cr(III) that may be detoxified by other mechanisms. Most characterized enzymes belong to the widespread NAD(P)H-dependent flavoprotein family of reductases. Several examples of bacterial systems protecting from the oxidative stress caused by chromate have been described. Other mechanisms of bacterial resistance to chromate involve the expression of components of the machinery for repair of DNA damage, and systems related to the homeostasis of iron and sulfur.

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

    Science.gov (United States)

    Yuan, Xianxia; Hu, Xin-Xin; Ding, Xin-Long; Kong, Hai-Chuan; Sha, Hao-Dong; Lin, He; Wen, Wen; Shen, Guangxia; Guo, Zhi; Ma, Zi-Feng; Yang, Yong

    2013-11-01

    A series of non-precious metal electrocatalysts, namely pyrolyzed carbon-supported cobalt-polypyrrole, Co-PPy-TsOH/C, are synthesized with various cobalt precursors, including cobalt acetate, cobalt nitrate, cobalt oxalate, and cobalt chloride. The catalytic performance towards oxygen reduction reaction (ORR) is comparatively investigated with electrochemical techniques of cyclic voltammogram, rotating disk electrode and rotating ring-disk electrode. The results are analyzed and discussed employing physiochemical techniques of X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, elemental analysis, and extended X-ray absorption fine structure. It shows that the cobalt precursor plays an essential role on the synthesis process as well as microstructure and performance of the Co-PPy-TsOH/C catalysts towards ORR. Among the studied Co-PPy-TsOH/C catalysts, that prepared with cobalt acetate exhibits the best ORR performance. The crystallite/particle size of cobalt and its distribution as well as the graphitization degree of carbon in the catalyst greatly affects the catalytic performance of Co-PPy-TsOH/C towards ORR. Metallic cobalt is the main component in the active site in Co-PPy-TsOH/C for catalyzing ORR, but some other elements such as nitrogen are probably involved, too.

  14. Atom Lithography with a Chromium Atomic Beam

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-Tao; LI Tong-Bao

    2006-01-01

    @@ Direct write atom lithography is a new technique in which resonant light is used to pattern an atomic beam and the nanostructures are formed when the atoms deposit on the substrate. We design an experiment setup to fabricate chromium nanolines by depositing an atomic beam of 52 Cr through an off-resonant laser standing wave with the wavelength of 425.55 nm onto a silicon substrate. The resulting nanolines exhibit a period of 215 ± 3 nm with height of 1 nm.

  15. Origin of hexavalent chromium in groundwater

    DEFF Research Database (Denmark)

    Kazakis, N.; Kantiranis, N.; Kalaitzidou, K.

    2017-01-01

    Hexavalent chromium constitutes a serious deterioration factor for the groundwater quality of several regions around the world. High concentrations of this contaminant have been also reported in the groundwater of the Sarigkiol hydrological basin (near Kozani city, NW Greece). Specific interest....... Accordingly, detailed geochemical, mineralogical, hydro-chemical, geophysical and hydrogeological studies were performed on the rocks, soils, sediments and water resources of this basin. Cr(VI) concentrations varied in the different aquifers, with the highest concentration (up to 120 μg L− 1) recorded...

  16. Observational Approach to Chromium Site Remediation - 13266

    Energy Technology Data Exchange (ETDEWEB)

    Scott Myers, R. [Washington Closure Hanford, 2620 Fermi, Richland, Washington 99354 (United States)

    2013-07-01

    Production reactors at the U.S. Department of Energy's (DOE) Hanford Site in Richland, Washington, required massive quantities of water for reactor cooling and material processing. To reduce corrosion and the build-up of scale in pipelines and cooling systems, sodium dichromate was added to the water feedstock. Spills and other releases at the makeup facilities, as well as leaks from miles of pipelines, have led to numerous areas with chromium-contaminated soil and groundwater, threatening fish populations in the nearby Columbia River. Pump-and-treat systems have been installed to remove chromium from the groundwater, but significant contamination remain in the soil column and poses a continuing threat to groundwater and the Columbia River. Washington Closure Hanford, DOE, and regulators are working on a team approach that implements the observational approach, a strategy for effectively dealing with the uncertainties inherent in subsurface conditions. Remediation of large, complex waste sites at a federal facility is a daunting effort. It is particularly difficult to perform the work in an environment of rapid response to changing field and contamination conditions. The observational approach, developed by geotechnical engineers to accommodate the inherent uncertainties in subsurface conditions, is a powerful and appropriate method for site remediation. It offers a structured means of quickly moving into full remediation and responding to the variations and changing conditions inherent in waste site cleanups. A number of significant factors, however, complicate the application of the observational approach for chromium site remediation. Conceptual models of contamination and site conditions are difficult to establish and get consensus on. Mid-stream revisions to the design of large excavations are time-consuming and costly. And regulatory constraints and contract performance incentives can be impediments to the flexible responses required under the

  17. ADVANCES IN HEXAVALENT CHROMIUM REMOVAL AT HANFORD

    Energy Technology Data Exchange (ETDEWEB)

    NESHEM DO; RIDDELLE J

    2012-01-30

    At the Hanford Site, chromium was used as a corrosion inhibitor in the reactor cooling water and was introduced into the groundwater as a result of planned and unplanned discharges from reactors during plutonium production since 1944. Beginning in 1995, groundwater treatment methods were evaluated leading to the use of pump and treat facilities with ion exchange using Dowex 21 K, a regenerable strong base anion exchange resin. This required regeneration of the resin, which is currently performed offsite. Resin was installed in a 4 vessel train, with resin removal required from the lead vessel approximately once a month. In 2007, there were 8 trains (32 vessels) in operation. In 2008, DOE recognized that regulatory agreements would require significant expansion in the groundwater chromium treatment capacity. Previous experience from one of the DOE project managers led to identification of a possible alternative resin, and the contractor was requested to evaluate alternative resins for both cost and programmatic risk reductions. Testing was performed onsite in 2009 and 2010, using a variety of potential resins in two separate facilities with groundwater from specific remediation sites to demonstrate resin performance in the specific groundwater chemistry at each site. The testing demonstrated that a weak base anion single-use resin, ResinTech SIR-700, was effective at removing chromium, had a significantly higher capacity, could be disposed of efficiently on site, and would eliminate the complexities and programmatic risks from sampling, packaging, transportation and return of resin for regeneration. This resin was installed in Hanford's newest groundwater treatment facility, called 100-DX, which began operations in November, 2010, and used in a sister facility, 100-HX, which started up in September of 2011. This increased chromium treatment capacity to 25 trains (100 vessels). The resin is also being tested in existing facilities that utilize Dowex 21 K for

  18. Composition tunable cobalt-nickel and cobalt-iron alloy nanoparticles below 10 nm synthesized using acetonated cobalt carbonyl

    Energy Technology Data Exchange (ETDEWEB)

    Schooneveld, Matti M. van, E-mail: M.M.vanSchooneveld@gmail.com; Campos-Cuerva, Carlos; Pet, Jeroen; Meeldijk, Johannes D. [Utrecht University, Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science (Netherlands); Rijssel, Jos van [Utrecht University, Van' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science (Netherlands); Meijerink, Andries [Utrecht University, Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science (Netherlands); Erne, Ben H. [Utrecht University, Van' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science (Netherlands); Groot, Frank M. F. de, E-mail: F.M.F.deGroot@uu.nl [Utrecht University, Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science (Netherlands)

    2012-08-15

    A general organometallic route has been developed to synthesize Co{sub x}Ni{sub 1-x} and Co{sub x}Fe{sub 1-x} alloy nanoparticles with a fully tunable composition and a size of 4-10 nm with high yield. In contrast to previously reported synthesis methods using dicobalt octacarbonyl (Co{sub 2}(CO){sub 8}), here the cobalt-cobalt bond in the carbonyl complex is first broken with anhydrous acetone. The acetonated compound, in the presence of iron carbonyl or nickel acetylacetonate, is necessary to obtain small composition tunable alloys. This new route and insights will provide guidelines for the wet-chemical synthesis of yet unmade bimetallic alloy nanoparticles.

  19. Bioleaching of chromium from tannery sludge by indigenous Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Wang, Yuan-Shan; Pan, Zhi-Yan; Lang, Jian-Min; Xu, Jian-Miao; Zheng, Yu-Guo

    2007-08-17

    Chromium in tannery sludge will cause serious environmental problems and is toxic to organisms. The acidophilic sulfur-oxidizing Acidithiobacillus thiooxidans can leach heavy metals form urban and industrial wastes. This study examined the ability of an indigenous sulfur-oxidizing A. thiooxidans to leach chromium from tannery sludge. The results showed that the pH of sludge mixture inoculated with the indigenous A. thiooxidans decreased to around 2.0 after 4 days. After 6 days incubation in shaking flasks at 30 degrees C and 160 rpm, up to 99% of chromium was solubilized from tannery sludge. When treated in a 2-l bubble column bioreactor for 5 days at 30 degrees C and aeration of 0.5 vvm, 99.7% of chromium was leached from tannery sludge. The results demonstrated that chromium in tannery sludge can be efficiently leached by the indigenous A. thiooxidans.

  20. CHROMIUM BIOACCUMULATION FROM COMPOSTS AND VERMICOMPOSTS BASED ON TANNERY SLUDGES

    Directory of Open Access Journals (Sweden)

    Krzysztof GONDEK

    2008-07-01

    Full Text Available Storage of waste substances is not indifferent to ecological equilibrium in the environment therefore should not be the ultimate way to limit waste arduousness. Therefore, the conducted investigations aimed to determine the effect of tannery composts and vermicomposts loaded with chromium on this element bioaccumulation in earthworm bodies and biomass of selected plants. Chromium in composts and vermicomposts based on tannery sludges occurred in small quantities and easily soluble compounds. Chromium concentrations in redworm biomass points to this metal accumulation in Eisenia fetida body tissues. This element content in redworm biomass was signifi cantly positively correlated with its content in composts. Chromium content in plants was diversifi ed and on treatments was generally smaller than on mineral treatment or farmyard manure. Chromium absorbed by plants was stored mainly in the root systems, and over the norm content of this element found in vermicomposts did not cause its excessive accumulation in plant biomass.