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Sample records for activation vanadium alloy

  1. VANADIUM ALLOYS

    Science.gov (United States)

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  2. Status of ATR-A1 irradiation experiment on vanadium alloys and low-activation steels

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Strain, R.V.; Gomes, I.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1996-10-01

    The ATR-A1 irradiation experiment was a collaborative U.S./Japan effort to study at low temperature the effects of neutron damage on vanadium alloys. The experiment also contained a limited quantity of low-activation ferritic steel specimens from Japan as part of the collaboration agreement. The irradiation started in the Advanced Test Reactor (ATR) on November 30, 1995, and ended as planned on May 5, 1996. Total exposure was 132.9 effective full power days (EFPDs) and estimated neutron damage in the vanadium was 4.7 dpa. The vehicle has been discharged from the ATR core and is scheduled to be disassembled in the next reporting period.

  3. Irradiation creep of vanadium-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  4. Vanadium-base alloys for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  5. Low activation ferritic alloys

    Science.gov (United States)

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  6. Corrosion resistance investigation of vanadium alloys in liquid lithium

    Science.gov (United States)

    Borovitskaya, I. V.; Lyublinskiy, I. E.; Bondarenko, G. G.; Paramonova, V. V.; Korshunov, S. N.; Mansurova, A. N.; Lyakhovitskiy, M. M.; Zharkov, M. Yu.

    2016-12-01

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10-3 wt %) of vanadium and vanadium alloys (V-1.86Ga, V-3.4Ga-0.62Si, V-4.81Ti-4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 1022 m-2 at an irradiation temperature of 400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  7. Gas tungsten arc welding of vanadium alloys with impurity control

    Science.gov (United States)

    Grossbeck, M. L.; King, J. F.; Nagasaka, T.; David, S. A.

    2002-12-01

    Gas tungsten arc welding in vanadium alloys is controlled by interstitial impurities. Techniques have been developed to weld V-4Cr-4Ti in a high-purity argon atmosphere resulting in a DBTT of -20 °C. The atmosphere was controlled by a Zr-Al getter which is activated at high temperature to obtain a clean surface then cooled and allowed to absorb hydrogen and oxygen impurities. Through the use of low-oxygen base metal and high-purity weld filler wire, a DBTT of -145 °C was obtained. Experiments using electron beam welding have shown that grain size also has an important effect on weld ductility. Introduction of nitrogen and yttrium has been used to study their effect on grain size. Using a combination of atmosphere control, alloy purity control, and grain size control, it is anticipated that V-Cr-Ti alloys will be weldable in field conditions.

  8. Research and development on vanadium alloys for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Matsui, H.; Abe, K. [Tohoku Univ. (Japan); Smith, D.L. [Argonne National Lab., IL (United States); Osch, E. van [NERF, Petten (Netherlands); Kazakov, V.A. [RIAR, Dimitrovgrad (Russian Federation)

    1998-03-01

    The current status of research and development on unirradiated and irradiated V-Cr-Ti alloys intended for fusion reactor structural applications is reviewed, with particular emphasis on the flow and fracture behavior of neutron-irradiated vanadium alloys. Recent progress on fabrication, joining, oxidation behavior, and the development of insulator coatings is also summarized. Fabrication of large (>500 kg) heats of V-4Cr-4Ti with properties similar to previous small laboratory heats has now been demonstrated. Impressive advances in the joining of thick sections of vanadium alloys using GTA and electron beam welds have been achieved in the past two years, although further improvements are still needed.

  9. Corrosion resistance investigation of vanadium alloys in liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Borovitskaya, I. V., E-mail: symp@imet.ac.ru [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Lyublinskiy, I. E. [JSC Red Star (Russian Federation); Bondarenko, G. G. [National Research University Higher School of Economics (Russian Federation); Paramonova, V. V. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Korshunov, S. N.; Mansurova, A. N. [National Research Center Kurchatov Institute (Russian Federation); Lyakhovitskiy, M. M. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Zharkov, M. Yu. [JSC Red Star (Russian Federation)

    2016-12-15

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10{sup –3} wt %) of vanadium and vanadium alloys (V–1.86Ga, V–3.4Ga–0.62Si, V–4.81Ti–4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 10{sup 22} m{sup –2} at an irradiation temperature of ~400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  10. Vanadium

    Science.gov (United States)

    Kelley, Karen D.; Scott, Clinton T.; Polyak, Désirée E.; Kimball, Bryn E.; Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Vanadium is used primarily in the production of steel alloys; as a catalyst for the chemical industry; in the making of ceramics, glasses, and pigments; and in vanadium redox-flow batteries (VRBs) for large-scale storage of electricity. World vanadium resources in 2012 were estimated to be 63 million metric tons, which include about 14 million metric tons of reserves. The majority of the vanadium produced in 2012 was from China, Russia, and South Africa.Vanadium is extracted from several different types of mineral deposits and from fossil fuels. These deposits include vanadiferous titanomagnetite (VTM) deposits, sandstone-hosted vanadium (with or without uranium) deposits (SSV deposits), and vanadium-rich black shales. VTM deposits are the principal source of vanadium and consist of magmatic accumulations of ilmenite and magnetite containing 0.2 to 1 weight percent vanadium pentoxide (V2O5). SSV deposits are another important source; these deposits have average ore grades that range from 0.1 to greater than 1 weight percent V2O5. The United States has been and is currently the main producer of vanadium from SSV deposits, particularly those on the Colorado Plateau. Vanadium-rich black shales occur in marine successions that were deposited in epeiric (inland) seas and on continental margins. Concentrations in these shales regularly exceed 0.18 weight percent V2O5 and can be as high as 1.7 weight percent V2O5. Small amounts of vanadium have been produced from the Alum Shale in Sweden and from ferrophosphorus slag generated during the reduction of phosphate to elemental phosphorus in ore from shales of the Phosphoria Formation in Idaho and Wyoming. Because vanadium enrichment occurs in beds that are typically only a few meters thick, most of the vanadiferous black shales are not currently economic, although they may become an important resource in the future. Significant amounts of vanadium are recovered as byproducts of petroleum refining, and processing of coal, tar

  11. Development of high purity vanadium alloys for fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Muroga, Takeo [National Inst. for Fusion Sience, Toki, Gifu (Japan)

    2002-07-01

    Vanadium alloys are most attractive candidate materials for liquid Li self-cooled blanket system of fusion reactors. This paper summarizes the program and its activities of the NIFS (National Institute for Fusion Science), Japan for developments of high purity V-4Cr-4Ti alloys. The results from NIFS-Heats show various benefits by reducing the level of oxygen. Significant improvement of the impact properties of the welded joint by reducing oxygen level is one of examples in recent studies. Collaboration is in progress, in which those heats are being characterized by a number of research groups including Japanese universities, and international collaboration partners in the US, Russia and China. The impact tests of irradiated speciments are in progress for further investigation. Significant progress has been made recently on the insulator ceramic coating in static conditions in the Japan-USA Cooperation Program. The understanding on the condition of in-situ CaO coating in liquid Li was enhanced. Based on these achievements, a flowing loop test is being planned to investigate the effects of temperature gradient and Li chemistry. (Y. Tanaka)

  12. Sputtered Clusters from Niobium-Vanadium Alloys

    DEFF Research Database (Denmark)

    Schou, Jørgen; Hofer, W. O.

    1982-01-01

    A series of Nb&z.sbnd;V alloys have been irradiated by 6 keV argon ions. Homonuclear and heteronuclear clusters emitted from these alloys have been studied by means of post-ionization and/or secondary ion mass spectrometry. The intensity of clusters of atomic masses up to approximately 300 amu...... was related to the concentrations of Nb and V in the alloys. In addition, the behaviour of polyatomic cluster yields as a function of partial oxygen pressure was studied. At partial pressures larger than approximately 10 6Torr, the yields decreased with increasing partial pressures. By inclusion of the post......-ionized neutrals, the total secondary particle intensity was increased by a factor of 1.5 for clusters up to atomic masses of around 200 amu. Scanning electron microscopy revealed a varied surface topography with large differences from grain to grain for irradiated samples exposed for doses larger than 1018 atoms...

  13. Studies of reactor irradiation effect on hydrogen isotope release from vanadium alloy V4Cr4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Kulsartov, T. [Kazakhstan State University, Tole-bi-str. 96a., Almaty (Kazakhstan); Shestakov, V. [Kazakhstan State University, Tole-bi-str. 96a., Almaty (Kazakhstan); Chikhray, Y. [Kazakhstan State University, Tole-bi-str. 96a., Almaty (Kazakhstan); Kenzhin, Y. [Institute of Atomic Energy NNC RK, Krasnoarmeyskaya-str. 10, Kurchatov (Kazakhstan); Kolbayenkov, A. [Institute of Atomic Energy NNC RK, Krasnoarmeyskaya-str. 10, Kurchatov (Kazakhstan); Tazhibayeva, I. [National Nuclear Center, Lenin-str. 6, Kurchatov (Kazakhstan)

    2007-08-01

    Vanadium alloys are most promising materials being considered for lithium blanket-breeder in future fusion reactors. The primary reason for these stems from good combination of physical-mechanical and radiation properties of vanadium alloys. In operational conditions of fusion reactors the very important issue is behavior of vanadium alloy with respect to hydrogen isotopes under neutron and gamma irradiation. This paper shows results of the experimental studies of reactor irradiation influence on parameters of hydrogen release from vanadium alloys. Experiments were carried out for various levels of reactor irradiation and showed the effect of irradiation on parameters of hydrogen release from vanadium alloy V4Cr4Ti.

  14. Development of laser welding techniques for vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-04-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Lasers do not require a vacuum (as do electron beam welders) and the welds they produce high depth-to-width ratios. Scoping with a small pulsed 50 J YAG laser indicated that lasers could produce successful welds in vanadium alloy (V-5%Cr-5%Ti) sheet (1 mm thick) when the fusion zone was isolated from air. The pulsed laser required an isolating chamber filled with inert gas to produce welds that did not contain cracks and showed only minor hardness increases. Following the initial scoping tests, a series of tests were preformed with a 6 kW continuous CO{sub 2} laser. Successful bead-on-plate welds were made on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys to depths of about 4 mm with this laser.

  15. Vanadium

    OpenAIRE

    Pourret, Olivier; Dia, Aline

    2017-01-01

    International audience; Vanadium (chemical symbol, V) is a d-block transition metal,silver in color, appearing in the first long period of the peri-odic table between titanium and chromium. Vanadium hastwo stable isotopes: 50V and 51V, with atomic abundance of0.25 % and 99.75 %, respectively. Vanadium has several oxidation forms (between 2+ and 5+). In the lithosphere, Voccurs as reducing V(III) form, whereas in oxidizing con- ditions V prevails under V(IV) form. Vanadium(II) is partic- ularl...

  16. Effects of vanadium on population growth and Na-K-ATPase activity of the brackish water hydroid Cordylophora caspia

    Energy Technology Data Exchange (ETDEWEB)

    Ringelband, U.; Karbe, L. [Institut fuer Hydrobiologie und Fischereiwissenschaft, Hamburg (Germany)

    1996-07-01

    Vanadium, a relatively abundant heavy metal, enters the environment naturally through rock weathering. A large fraction of vanadium input is of human origin. The combustion of petroleum- and coal-products, which contain relatively high concentrations of vanadium, is one of the most important sources of the enrichment of vanadium in the environment. As it is used as an alloy, and vanadium rich iron-ores of various origin are used in steel production, the residual slag-stones of the steel industry can contain considerable vanadium concentrations. Wherever slag-stones serve as a cheap and convenient material in riverbank reinforcement, vanadium can leach into the aquatic environment. Vanadium is regarded as an essential trace element for higher animals. Cantley et al. indicated a regulatory function of vanadate in vivo. Although considerable information is available on the toxic effects of vanadium on humans, very little is known about the toxicity of vanadium towards aquatic organisms, especially invertebrates. Bell and Sargent have shown an inhibition of Na-K-ATPase activity in gills of the eel Anguilla anguilla. Holleland and Towle have demonstrated the inhibition of Na-K-ATPase activity in the gills of the shore crab Carcinus maenas. The aim of this study was to determine the toxicity of vanadium towards the brackish water hydroid Cordylophora caspia. Hydroids are known to be particularly sensitive to heavy metals and their asexual reproduction can be used in a well-established population growth test. Furthermore, the effects of vanadium on Na-K-ATPase activity in hydroids were studied in in vivo experiments, wherein the animals were exposed to sublethal concentrations of vanadium. In addition, the inhibition of Na-K-ATPase was measured in vitro, by adding vanadium to a microsomal preparation. 16 refs., 4 figs.

  17. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-04-01

    V-4Cr-4-Ti alloy has been recently selected for use in the manufacture of a portion of the DIII-D Radiative Divertor modification, as part of an overall DIII-D vanadium alloy deployment effort developed by General Atomics (GA) in conjunction with the Argonne and Oak Ridge National Laboratories (ANL or ORNL). The goal of this work is to produce a production-scale heat of the alloy and fabricate it into product forms for the manufacture of a portion of the Radiative Divertor (RD) for the DIII-D tokamak, to develop the fabrications technology for manufacture of the vanadium alloy radiative Divertor components, and to determine the effects of typical tokamak environments in the behavior of the vanadium alloy. The production of a {approx}1300-kg heat of V-4Cr-4Ti alloy is currently in progress at Teledyne Wah Chang of Albany, oregon (TWCA) to provide sufficient material for applicable product forms. Two unalloyed vanadium ingots for the alloy have already been produced by electron beam melting of raw processes vanadium. Chemical compositions of one ingot and a portion of the second were acceptable, and Charpy V-Notch (CVN) impact test performed on processed ingot samples indicated ductile behavior. Material from these ingots are currently being blended with chromium and titanium additions, and will be vacuum-arc remelted into a V-4Cr-4Ti alloy ingot and converted into product forms suitable for components of the DIII-D RD structure. Several joining methods selected for specific applications in fabrication of the RD components are being investigated, and preliminary trials have been successful in the joining of V-alloy to itself by both resistance and inertial welding processes and to Inconel 625 by inertial welding.

  18. Comparison of hypoglycemic activity and toxicity of vanadium (IV) and vanadium (V) absorbed in fermented mushroom of Coprinus comatus.

    Science.gov (United States)

    Ma, Zhaoji; Fu, Qin

    2009-12-01

    This study was designed to evaluate the effect and toxicity of administration of vanadium (IV, V) absorbed by Coprinus comatus (VACC) on alloxan-induced and sucrosefed hyperglycemic mice, respectively. The blood glucose, lipid profile, and the organ masses of the mice were analyzed. After the mice were administered with VACC, the blood glucose and the lipid profile of hyperglycemic mice decreased, irrespective of the VACC produced by vanadium (IV) or vanadium (V). However, the organ masses of the mice were significantly different after the mice were treated with vanadium (IV) and vanadium (V) 9 weeks later. The results indicate both vanadium (IV) and vanadium (V) absorbed in C. comatus have hypoglycemic activity on hyperglycemic mice. However, vanadium (IV) absorbed in C. comatus is less toxic to mice than vanadium (V).

  19. Hydrogen Release from Irradiated Vanadium Alloy V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Klepikov, A. Kh.; Romanenko, O. G.; Chikhray, E. V.; Tazhibaeva, I. L.; Shestakov, V. P.; Longhurst, Glen Reed

    1999-09-01

    The present work is an attempt to obtain data concerning the influence of neutron and ? irradiation upon hydrogen retention in V-4Cr-4Ti vanadium alloy. The experiments on in-pile loading of vanadium alloy specimens at the neutron flux density 1014 n/cm2s, hydrogen pressure of 80 Pa, and temperatures of 563, 613, and 773 K were carried out using the IVG.1M reactor of the Kazakhstan National Nuclear Center. A preliminary set of loading/degassing experiments with non-irradiated material has been carried out to obtain data on hydrogen interaction with vanadium alloy. The, data presented in this work are related both to non-irradiated and irradiated samples.

  20. Allergic reaction to vanadium causes a diffuse eczematous eruption and titanium alloy orthopedic implant failure.

    Science.gov (United States)

    Engelhart, Sally; Segal, Robert J

    2017-04-01

    Allergy as a cause of adverse outcomes in patients with implanted orthopedic hardware is controversial. Allergy to titanium-based implants has not been well researched, as titanium is traditionally thought to be inert. We highlight the case of a patient who developed systemic dermatitis and implant failure after surgical placement of a titanium alloy (Ti6Al4V) plate in the left foot. The hardware was removed and the eruption cleared in the following weeks. The plate and screws were submitted for metal analysis. The elemental composition of both the plate and screws included 3 major elements-titanium, aluminum, and vanadium-as well as trace elements. Metal analysis revealed that the plate and screws had different microstructures, and electrochemical studies demonstrated that galvanic corrosion could have occurred between the plate and screws due to their different microstructures, contributing to the release of vanadium in vivo. The patient was patch tested with several metals including components of the implant and had a positive patch test reaction only to vanadium trichloride. These findings support a diagnosis of vanadium allergy and suggests that clinicians should consider including vanadium when patch testing patients with a suspected allergic reaction to vanadium-containing implants.

  1. New, high-capacity alloys for hydrogen batteries. Vanadium alloys with microcurrent collecting function; Atarashii suiso denchiyo koyoryo gokin. Maikuro shuden kino wo sonaeta vanadium gokin

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, T. [Osaka National Research Institute, Osaka (Japan)

    1996-05-01

    In an attempt to provide vanadium-base alloys with microcurrent collecting functions and corrosion resistance, their compositions and metallic microstructures are controlled. This leads to development of a new alloy for batteries, which shows an electrical capacity at least 1.5 times higher than that of the conventional rare-earth alloys. A detailed phase diagram of the V-Ti-Ni systems is drawn for hydrogen occluding, to determine the optimum composition. For the electrode characteristics of V3TiNix, the discharge characteristics are notably improved as Ni content increases. For the microstructures, Ni is scarcely dissolved in the base phase of V, withdraws Ti from the base phase, and separates out in the grain boundaries as a TiNi phase dissolving part of V, to form micronetworks. These phenomena are considered to impart the internal microcurrent collecting function to the vanadium alloy. The composition of V3TiNi0.56 shows an initial capacity of 400Ah/g or higher. 3 refs., 5 figs.

  2. Production of high-purity vanadium, chromium and titanium for use in low activation materials

    Science.gov (United States)

    Murphy, D.; Butterworth, G. J.

    1992-09-01

    The presence of radiologically potent tramp elements must be strictly controlled if the intrinsic low activation properties of alloys based on vanadium and chromium are to be fully realized. In this study the incidence of critical impurity elements in commercial sources of vanadium, chromium and titanium metals and precursor compounds is investigated using techniques for trace element analysis. Maximum permitted concentrations corresponding to the attainment of the “hands-on” dose rate limit of 25 μSvh-1 after 100 yr cooling of first wall material were adopted as target values. Chromium and titanium from commercial sources are able to satisfy the purity target. Commercially available vanadium may contain unacceptable levels of Mo, Ag, Nb or Co and additional purification steps designed to remove these impurities are described.

  3. Microstructural and microchemical evolution in vanadium alloys by heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sekimura, Naoto; Kakiuchi, Hironori; Shirao, Yasuyuki; Iwai, Takeo [Tokyo Univ. (Japan)

    1996-10-01

    Microstructural and microchemical evolution in vanadium alloys were investigated using heavy ion irradiation. No cavities were observed in V-5Cr-5Ti alloys irradiated to 30 dpa at 520 and 600degC. Energy dispersive X-ray spectroscopy analyses showed that Ti peaks around grain boundaries. Segregation of Cr atoms was not clearly detected. Co-implanted helium was also found to enhance dislocation evolution in V-5Cr-5Ti. High density of matrix cavities were observed in V-5Fe alloys irradiated with dual ions, whereas cavities were formed only around grain boundaries in single ion irradiated V-5Fe. (author)

  4. Effects of irradiation to 4 dpa at 390 C on the fracture toughness of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, E.E.; Galvin, T.M.; Chopra, O.K. [Argonne National Lab., IL (United States)

    1998-09-01

    Fracture toughness J-R curve tests were conducted at room temperature on disk-shaped compact-tension DC(T) specimens of three vanadium alloys having a nominal composition of V-4Cr-4Ti. The alloys in the nonirradiated condition showed high fracture toughness; J{sub IC} could not be determined but is expected to be above 600 kJ/m{sup 2}. The alloys showed very poor fracture toughness after irradiation to 4 dpa at 390 C, e.g., J{sub IC} values of {approx}10 kJ/m{sup 2} or lower.

  5. Electrochemistry of vanadium(II and the electrodeposition of aluminum-vanadium alloys in the aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt

    Directory of Open Access Journals (Sweden)

    Tsuda T.

    2003-01-01

    Full Text Available The electrochemical behavior of vanadium(II was examined in the 66.7-33.3 mole percent aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt containing dissolved VCl2 at 353 K. Voltammetry experiments revealed that V(II could be electrochemically oxidized to V(III and V(IV. However at slow scan rates the V(II/V(III electrode reaction is complicated by the rapid precipitation of V(III as VCl3. The reduction of V(II occurs at potentials considerably negative of the Al(III/Al electrode reaction, and Al-V alloys cannot be electrodeposited from this melt. However electrodeposition experiments conducted in VCl2-saturated melt containing the additive, 1-ethyl-3-methylimidazolium tetrafluoroborate, resulted in Al-V alloys. The vanadium content of these alloys increased with increasing cathodic current density or more negative applied potentials. X-ray analysis of Al-V alloys that were electrodeposited on a rotating copper wire substrate indicated that these alloys did not form or contain an intermetallic compound, but were non-equilibrium or metastable solid solutions. The chloride-pitting corrosion properties of these alloys were examined in aqueous NaCl by using potentiodynamic polarization techniques. Alloys containing ~10 a/o vanadium exhibited a pitting potential that was 0.3 V positive of that for pure aluminum.

  6. Particle reflections of low energy light ions from a vanadium alloy (V-4Cr-4Ti)

    Energy Technology Data Exchange (ETDEWEB)

    Yamaoka, H. [Harima Institute, RIKEN The Institute of Physical and Chemical Research, 1-1-1 Kouto, Sayo, Hyogo 679-5148 (Japan)]. E-mail: yamaoka@spring8.or.jp; Tanaka, N. [Tohoku University, Sendai 980-8579 (Japan)]. E-mail: nozomi.tanaka@ppl2.qse.tohoku.ac.jp; Matsumoto, Y. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Nishiura, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Tsumori, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Takeuchi, S. [Tohoku University, Sendai 980-8579 (Japan); Sugawara, H. [Tohoku University, Sendai 980-8579 (Japan); Shinto, K. [Tohoku University, Sendai 980-8579 (Japan); Okamoto, A. [Tohoku University, Sendai 980-8579 (Japan); Sasao, M. [Tohoku University, Sendai 980-8579 (Japan); Wada, M. [Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

    2007-06-15

    The angular distributions and energy spectra of positive and negative ions reflected from a vanadium alloy (V-4Cr-4Ti) bombarded by beams of low energy (1-2 keV) ions of H, He, and O were measured. The intensities of H{sup +} or H{sup -} produced from reflection of 2 keV H{sup +} beam at the surface of vanadium alloy showed the maxima at the angles closer to the surface normal from the mirror reflection angle, compared with Mo and W samples. The time dependence of the angular distributions of the reflected H{sup +} or H{sup -} ions measured at the sample temperature of about 240-260 {sup o}C showed a shift of the peak in the angular distribution to the mirror reflection angle.

  7. Proceedings of the 2. workshop on vanadium alloy development for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Osch, E.V. van [ed.

    1996-10-01

    From 20 to 22 May 1996 the Second IEA Vanadium Alloy Development for Fusion Workshop was held at the Netherlands Energy Research Foundation, ECN in Petten. Twenty three experts from the European Union, Japan, the Russian Federation and the United States exchanged results and analyses of completed experiments and discussed the program planning. The manufacturing of half-finished products and the optimization of subsequent heat treatments were presented and discussed in the first session. The problems and solutions to joining vanadium alloy half-finished products by welding and brazing have been addressed in another session. Corrosion and compatibility properties have been evaluated in a different session together with coating requirements. Several sessions were devoted to the effects of radiation on the mechanical properties, especially toughness, of vanadium alloys. Also the role of the transmutation product helium, in particular its introduction into specimens, was evaluated. The respective plans of the four parties for continuation of the ongoing research and development programs have been discussed with the emphasis on avoiding duplications in the area of radiation experiments. The critical issues were identified and the related priorities discussed in the time frame set by the schedule for the building of ITER test modules and with the long term DEMO requirements in mind. (orig.).

  8. Medium carbon vanadium micro alloyed steels for drop forging

    Energy Technology Data Exchange (ETDEWEB)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1992-12-31

    Growing competitiveness of alternative manufacturing routes requires cost minimization in the production of drop forged components. The authors analyse the potential of medium carbon, vanadium microalloyed steels for drop forging. Laboratory and industrial experiments have been carried out emphasizing deformation and temperature cycles, strain rates and dwell times showing a typical processing path, associated mechanical properties and corresponding microstructures. The steels the required levels of mechanical properties on cooling after forging, eliminating subsequent heat treatment. The machinability of V-microalloyed steels is also improved when compared with plain medium carbon steels. (author) 17 refs., 19 figs., 5 tabs.

  9. Development of laser welding techniques for vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Leong, K.H.; Smith, D.L. [Argonne National Laboratory, IL (United States)

    1996-10-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Bead-on-plate and butt welds were previously performed to depths of about 4 mm with a 6-kW CO{sub 2} laser on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys. These welds were made at a speed of 0.042 m/s using argon purging at a flow rate of 2.8 m{sup 3}/s. The purge was distributed with a diffuser nozzle aimed just behind the laser beam during the welding operation. The fusion zones of welds made under these conditions consisted of very fine, needle-shaped grains and were also harder than the bulk metal (230-270 dph, compared to {approx}180 dph for the bulk metal). A limited number of impact tests showed that the as-welded ductile-brittle transition temperatures (DBTT) was above room temperature, but heat treatment at 1000{degrees}C for 1 h in vacuum reduced the DBTT to <{minus}25{degrees}C. Activities during this reporting period focused on improvements in the purging system and determination of the effect of welding speed on welds. A 2-kW continuous YAG laser at Lumonics Corp. in Livonia, MI, was used to make 34 test welds for this study.

  10. Microstructure evolutions of graded high-vanadium tool steel composite coating in-situ fabricated via atmospheric plasma beam alloying

    NARCIS (Netherlands)

    Cao, Huatang; Dong, XuanPu; Chen, Shuqun; Dutka, Mikhail; Pei, Yutao

    2017-01-01

    A novel high-vanadium based hard composite coating was synthesized from premixed powders (V, Cr, Mo, Ti, Nb) on ductile iron (DI) substrate via atmospheric plasma beam surface alloying process. The graded coating can be divided into three distinct zones: upper alloyed zone (AZ) rich with spherical

  11. Simultaneous first order derivative spectrophotometric determination of vanadium and zirconium in alloy steels and minerals.

    Science.gov (United States)

    Varghese, Anitha; George, Louis

    2012-09-01

    A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of trace amounts of vanadium(V) and zirconium(IV) in acetic acid medium using a newly synthesised reagent diacetylmonoxime salicyloylhydrazone (DMSH), without any prior separation. The molar absorptivity and Sandell's sensitivity of the coloured species are 1.30 x 10(4) and 1.82 x 10(4) L mol(-1)cm(-1) and 3.9 and 2.5 ng cm(-2) for V(V) and Zr(IV), respectively. Beer's law is obeyed between 0.26-2.80 and 0.30-3.20 μg mL(-1) concentration of vanadium (V) and zirconium (IV) at 405 and 380 nm respectively. The stoichiometry of the complex was found to be 1:1 (metal:ligand) for V(V) and 1:2 for Zr(IV) complexes. These metal ions interfere with the determination of each other in zero order spectrophotometry. The first derivative spectra of these complexes permitted a simultaneous determination of V(V) and Zr(IV) at zero crossing wavelengths of 445 nm and 405 nm, respectively. The optimum conditions for maximum colour development and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of zirconium and vanadium in standard alloy steel samples, mineral and soil samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Surface cracking of tungsten-vanadium alloys under transient heat loads

    Directory of Open Access Journals (Sweden)

    Kameel Arshad

    2015-07-01

    Full Text Available To evaluate high heat load performance of tungsten-vanadium (W-V alloys as a potential candidate for plasma facing materials of fusion devices, the target materials with three different V concentrations (1, 5 and 10 wt% are exposed to thermal shock loading. The alloys are fabricated by cold isostatic pressing and subsequently sintered in a vacuum furnace. Thereafter, they are exposed to different high heat flux densities ranging from 340 to 675 MW/m2 for single shot of 5 ms duration in an intense electron beam test facility. The alloys with lowest V concentration (1 wt% are highly damaged in form of seriously cracking. The ones with intermediate V content (5 wt% has shown comparatively better performance than both highest and lowest V contents alloys. The results indicate that improved mechanical properties and reduced thermal conductivity due to V addition comprehensively affect the cracking behavior of W-V alloy under transient thermal shock.

  13. Hard-yet-tough high-vanadium high-speed steel composite coating in-situ alloyed on ductile iron by atmospheric plasma arc

    NARCIS (Netherlands)

    Cao, Huatang; Dong, Xuanpu; Pei, Yutao T.

    2018-01-01

    A graded high-vanadium alloy composite coating was synthesized from premixed powders (V, Cr, Ti, Mo, Nb) on ductile iron (DI) substrate via atmospheric plasma arc surface alloying process. The resulted cross-section microstructure is divided into three distinct zones: upper alloyed zone (AZ) rich

  14. Impact properties of vanadium-base alloys irradiated at < 430 C

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-03-01

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys.

  15. Feasibility of conducting a dynamic helium charging experiment for vanadium alloys in the advanced test reactor

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Gomes, I.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1996-10-01

    The feasibility of conducting a dynamic helium charging experiment (DHCE) for vanadium alloys in the water-cooled Advanced Test Reactor (ATR) is being investigated as part of the U.S./Monbusho collaboration. Preliminary findings suggest that such an experiment is feasible, with certain constraints. Creating a suitable irradiation position in the ATR, designing an effective thermal neutron filter, incorporating thermocouples for limited specimen temperature monitoring, and handling of tritium during various phases of the assembly and reactor operation all appear to be feasible. An issue that would require special attention, however, is tritium permeation loss through the capsule wall at the higher design temperatures (>{approx}600{degrees}C). If permeation is excessive, the reduced amount of tritium entering the test specimens would limit the helium generation rates in them. At the lower design temperatures (<{approx}425{degrees}C), sodium, instead of lithium, may have to be used as the bond material to overcome the tritium solubility limitation.

  16. Comparison of vanadium-rich activity of three species fungi of basidiomycetes.

    Science.gov (United States)

    Han, Chunchao; Cui, Bo; Qu, Jingran

    2009-03-01

    A comparison of vanadium-rich activity of three species fungi of Basidiomycetes, Ganoderma lucidum, Coprinus comatus, and Grifola frondosa, was studied. By fermentation and atomic absorption spectroscopy analysis, the biomass of G. lucidum and G. frondosa declined rapidly when the concentration of vanadium exceeded 0.3% but the biomass of C. comatus did not decline rapidly until the concentration of vanadium exceeded 0.4% and the content of vanadium accumulated in the mycelia was 3529.3 microg/g. After the mice were administered (intragastrically) with vanadium-rich C. comatus, the blood glucose of alloxan-induced hyperglycemic mice was decreased (p comatus to absorb vanadium and chose 0.4% as the optimal concentration of vanadium for the pharmacological works.

  17. Hypoglycemic activity of Grifola frondosa rich in vanadium.

    Science.gov (United States)

    Cui, Bo; Han, Linna; Qu, Jingran; Lv, Yingtao

    2009-11-01

    The hypoglycemic activity of fermented mushroom of Grifola frondosa rich in vanadium (GFRV) was studied in this paper. Alloxan- and adrenalin-induced hyperglycemic mice were used in the study. The blood glucose and the HbA1c of the mice were analyzed respectively. After the mice were administered (ig) with GFRV, the blood glucose and the HbA1c of alloxan-induced hyperglycemic mice decreased (p < 0.05, p < 0.01) and ascension of blood glucose induced by adrenalin was inhibited (p < 0.01). Also, the bodyweight of the alloxan-induced hyperglycemic mice was increased gradually. In the fermented mushroom of G. frondosa, vanadium at lower doses in combination with G. frondosa induced significant decreases of the blood glucose and HbA1c levels in hyperglycemic mice.

  18. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kun; Liu, Junyao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Lei, Ting, E-mail: tlei@mail.csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Xiao, Tao [2nd Xiangya Hospital, Central South University, Changsha 410011 (China)

    2015-10-30

    Highlights: • The optimum operating conditions were determined by an orthogonal experiment. • The coating is composed of oxides and hydroxides of V{sup 5+}, V{sup 4+} and Mg(OH){sub 2}. • The self-healing performance was investigated by cross-cut immersion test. • The vanadia conversion coating provided active corrosion protection to AZ31 alloy. - Abstract: A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  19. Effect of Cr and Ti contents on the recovery, recrystallization, and mechanical properties of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gubbi, A.N.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L. [Oak Ridge National Laboratory, TN (United States)] [and others

    1996-04-01

    A series of vacuum-anneals at temperatures from 900 to 100{degrees}C for 1 to 4 h was carried out on small heats of vanadium alloys with Cr and Ti contents ranging from 2 to 6wt. %. The alloys examined on this work were V-3Cr-3Ti, V-4Cr-4Ti, V-5Cr-5Ti, V-6Cr-3Ti, and V-6Cr-6Ti. Optical miscroscopy, TEM, and microhardness testing were conducted. Variation in Cr and Ti over the range of 3 to 6 wt% had no discernible effect on recovery/recrystallization behavior. The hardness of both recovered and recrystallized structures increased with total (CR + Ti) content. In order to study the effect of Cr and Ti content on mechanical properties, Charpy impact testing and tensile testing were carried out on small heats of compositional variants. The V-4Cr-4Ti-Si alloy, in a fully recrystallized conditions, exhibited a high level of resistance to cleavage failure with a DBTT at {approx} 190{degrees}C. The alloy containing higher concentrations of Cr and Ti, in a fully recrystallized condition, exhibited a DBTT around -100{degrees}C, whereas the V-3Cr-3Ti alloy failed by pure ductile shear at liquid nitrogen temperature without any ductile-to-brittle transition. Tensile testing was conducted on SS-3 tensile specimens punched from 0.762-mm-thick plates of V-3Cr-3Ti and V-6Cr-6Ti. The tests were done in air at temperature at strain rates ranging from 10{sup -3} to 2x10{sup -1}/s. For V-6Cr-6Ti, both the 0.2% yield stress (YS) and the ultimate tensile strength (UTS) were higher than those for V-3Cr-3Ti at all strain rates. Both YS and UTS showed a similiar trend in incremental increase with strain rate for the two alloys. In the same token, both alloys exhibited an identical behavior of almost no change in uniform and total elongation up to a strain rate of 10{sup -1}/s and a decrease with further increase in strain rate.

  20. Dose dependence of irradiation hardening of neutron irradiated vanadium alloys by using temperature control rig in JMTR

    Directory of Open Access Journals (Sweden)

    Ken-ichi Fukumoto

    2016-12-01

    Full Text Available TEM observation and tensile test were examined for vanadium alloys irradiated in a temperature control rig in JMTR at 290°C with damage level ranged from 0.003 to 0.06dpa. With the increase of the neutron dose, irradiation hardening could be observed in all the vanadium alloys except for the V–5Nb alloy. In the case of pure vanadium, the relationship between irradiation hardening and neutron dose was described as Δσ ∝ (ϕt0.35-0.53. For V–5Cr alloy and V–4Cr–4Ti–0.1Si alloy, the dose dependence on irradiation hardening increase was shown as Δσ ∝ (ϕt0.8 and Δσ ∝ (ϕt0.8-1.0, respectively. From the TEM observation, the hardening source of radiation-induced defects was mainly determined to be dislocation loops for pure vanadium, loops with voids for V–5Cr and, loops and {100} precipitates for V–4Cr–4Ti–0.1Si and V–3Fe–4Ti–0.1Si alloys. From the strain rate dependence of 8% stress for V–4Cr–4Ti–0.1Si alloys tested at RT, the strain rate sensitivity, m=1/σ*(dσ/dln(dε/dt shows positive. Therefore, the dynamic interaction between interstitial impurities and dislocation is not strong in V–4Cr–4Ti alloys in the temperature range from RT to 290°C. A discrepancy of deformation mode of irradiated V–4Cr–4Ti–0.1Si alloys with 0.068dpa could be seen when the charpy impact test indicated the brittle behavior and the tensile test indicated the ductile behavior at room temperature. It can be explained by the difference of strain rate for the value of yield stress between tensile test and charpy test and the critical fracture stress.

  1. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  2. Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel

    Science.gov (United States)

    Nechaykina, Tatyana A.; Nikulin, Sergey A.; Rozhnov, Andrey B.; Khatkevich, Vladimir M.; Rogachev, Stanislav O.

    2017-03-01

    The present work is devoted to the development of new structural composite material having the unique complex of properties for operating in ultrahard conditions that combine high temperatures, radiation, and aggressive environments. A new three-layer composite tube material based on vanadium alloy (V-4Ti-4Cr) protected by stainless steel (Fe-0.2C-13Cr) has been obtained by co-extrusion. Mechanism and kinetics of formation as well as structure, composition, and mechanical properties of "transition" area between vanadium alloy and stainless steel have been studied. The transition area (13- to 22- µm thick) of the diffusion interaction between vanadium alloy and steel was formed after co-extrusion. The microstructure in the transition area was rather complicated comprising different grain sizes in components, but having no defects or brittle phases. Tensile strength of the composite was an average 493 ± 22 MPa, and the elongation was 26 ± 3 pct. Annealing at 1073 K (800 °C) increased the thickness of transition area up to 1.2 times, homogenized microstructure, and slightly changed mechanical properties. Annealing at 1273 K (1000 °C) further increased the thickness of transition area and also lead to intensive grain growth in steel and sometimes to separation between composite components during tensile tests. Annealing at 1073 K (800 °C) is proposed as appropriate heat treatment after co-extrusion of composite providing balance between diffusion interaction thickness and microstructure and monolithic-like behavior of composite during tensile tests.

  3. Surface alloying of high-vanadium high-speed steel on ductile iron using plasma transferred arc technique: Microstructure and wear properties

    NARCIS (Netherlands)

    Cao, H.T.; Dong, X.P.; Pan, Z.; Wu, X.W.; Huang, Q.W.; Pei, Y.T.

    2016-01-01

    A high-vanadium high speed steel (HVHSS) alloying layer was synthesized from pre-placed powders (V-Cr-Ti-Mo) on ductile iron (DI) substrate using plasma transferred arc (PTA) technique. The PTA-alloyed layer, characterized by microhardness, optical microscopy, XRD, EDS enabled SEM, TEM and

  4. A replica technique for extracting precipitates from neutron-irradiated or thermal-aged vanadium alloys for TEM analysis

    Science.gov (United States)

    Fukumoto, K.; Iwasaki, M.

    2014-06-01

    A carbon replica technique has been developed to extract precipitates from vanadium alloys. Using this technique, precipitation phases can be extracted from neutron-irradiated or thermal-aged V-4Cr-4Ti alloys. Precipitate identification using EDS X-ray analysis and electron diffraction was facilitated. Only NaCl type of Ti(OCN) precipitate was formed in the thermal-aged V-4Cr-4Ti alloys at 600 °C for 20 h and cation sub-lattice was only occupied by Ti atoms. However, the thin plate of precipitates with NaCl type of crystallographic structure could be seen in the V-4Cr-4Ti alloys irradiated at 593 °C in the JOYO fast reactor. The precipitate contained chromium and vanadium atoms on the cation sub-lattice as well as titanium atoms. It is considered that the phase of MX type (M = Ti, V, Cr and X = O, N, C) is a metastable phase under neutron irradiation.

  5. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, IL (United States)

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  6. Comparison of mechanical properties and structure of vanadium alloys relevant to DEMO conditions of the first wall and blanket

    Science.gov (United States)

    Budilkin, N. I.; Alekseev, A. B.; Golikov, I. V.; Kazennov, Yu. I.; Khramtsov, V. F.; Mironova, E. G.; Tselischev, A. V.

    1996-10-01

    Base metal flat specimens and specimens with weld joint of two vanadium alloys V4Ti4Cr and V10Ti5Cr were tested for a tension at 20-700°C. At all temperatures of tests V10Ti5Cr alloy specimens of base metal have higher values of yield stress and tensile strength than the same specimens of V4Ti4Cr alloy. Distinction of two alloys in value of specific elongation is less appreciable. The presence of weld joint does not lead to a significant change of the character of temperature dependence and tensile strength value, but reduces plasticity of alloys at 20-700°C. The effect of plasticity reduction of the alloy V4Ti4Cr depends on the method of welding, however the total elongation remains at a level 11.0-19.0% for gas tungsten arc (GTA) welding and 12.5-22.5% for electron beam (EB) welding. Fractography by a SEM method has shown a mixed (ductile—brittle) character of fracture of joint weld specimens with a less part of brittle component.

  7. Processing, characterization, and bactericidal activity of undoped and silver-doped vanadium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tousley, M.E.; Wren, A.W.; Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States); Mellott, N.P., E-mail: mellott@alfred.edu [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States)

    2012-12-14

    Vanadium oxide (V) and silver-doped vanadium oxide (Ag-V) powders were prepared via sol-gel processing. Structural evolution and bactericidal activity was examined as a function of temperature ranging from 250, 350, 450 and 550 Degree-Sign C. Powders were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. Results from all techniques showed vanadium pentoxide (V{sub 2}O{sub 5}) is the predominant phase regardless of heat treatment temperature or the addition of silver (Ag). XRD analysis suggests Ag is present as AgCl in samples heat treated to 250, 350, and 450 Degree-Sign C and as AgV{sub 6}O{sub 15} at 550 Degree-Sign C. Bactericidal activity was evaluated against Escherichia coli using the agar disk diffusion method considering both Ag-V and undoped, V powders. While the addition of Ag significantly increased bactericidal properties, the specific Ag valency, or crystal structure and morphology formed at higher temperatures, had little effect on functionality. -- Highlights: Black-Right-Pointing-Pointer Vanadium and silver-doped vanadium oxide powders were prepared via sol-gel. Black-Right-Pointing-Pointer Powders were characterized using advanced, complementary structural techniques. Black-Right-Pointing-Pointer Bactericidal activity was evaluated against E. coli. Black-Right-Pointing-Pointer Both vanadium and silver doped vanadium oxide show bactericidal activity.

  8. A comparison of hypoglycemic activity of three species of basidiomycetes rich in vanadium.

    Science.gov (United States)

    Han, Chunchao; Liu, Tongjun

    2009-02-01

    The hypoglycemic activity of fermented mushroom of three fungi of basidiomycetes rich in vanadium was studied in this paper. Alloxan- and adrenalin-induced hyperglycemic mice were used in the study. The blood glucose and the sugar tolerance were determined. After the mice were administered (ig) with Coprinus comatus rich in vanadium, the blood glucose of alloxan-induced hyperglycemic mice decreased (p Coprinus comatus rich in vanadium on hyperglycemic animals are significant; it may be used as a hypoglycemic food or medicine for hyperglycemic people.

  9. One-pot synthesis of optically active allyl esters via lipase-vanadium combo catalysis.

    Science.gov (United States)

    Akai, Shuji; Hanada, Ryosuke; Fujiwara, Noboru; Kita, Yasuyuki; Egi, Masahiro

    2010-11-05

    The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution.

  10. Is vanadium a more versatile target in the activity of primordial life forms than hitherto anticipated?

    Science.gov (United States)

    Rehder, Dieter

    2008-03-21

    The two predominant forms of vanadium occurring in the geo-, aqua- and biosphere, soluble vanadate(V) and insoluble oxovanadium(IV) (vanadyl), are subject to bacterial activity and transformation. Bacteria belonging to genera such as Shewanella, Pseudomonas and Geobacter can use vanadate as a primary electron acceptor in dissimilation or respiration, an important issue in the context of biomineralisation and soil detoxification. Azotobacter, which can employ vanadium as an essential element in nitrogen fixation, secretes a vanadophore which enables the uptake of vanadium(V). Siderophores secreted by other bacteria competitively (to ferric iron) take up vanadyl and thus interfere with iron supply, resulting in bacteriostasis. The halo-alkaliphilic Thioalkalivibrio nitratireducens possibly uses vanadium as a constituent of an alternative, molybdopterin-free nitrate reductase. Marine macro-algae can generate a variety of halogenated organic compounds by use of vanadate-dependent haloperoxidases, and a molecular vanadium compound, amavadin, from Amanita mushrooms has turned out to be an efficient catalyst in oxidation reactions. The present account is a focused and critical review of the current knowledge of the interplay of bacteria and other primitive forms of life (cyanobacteria, algae, fungi and lichens) with vanadium, with the aim to provide perspectives for applications and further investigations.

  11. Multilayer "Steel/Vanadium Alloy/Steel" Hybrid Material Obtained by High-Pressure Torsion at Different Temperatures

    Science.gov (United States)

    Rogachev, S. O.; Nikulin, S. A.; Rozhnov, A. B.; Khatkevich, V. M.; Nechaykina, T. A.; Gorshenkov, M. V.; Sundeev, R. V.

    2017-12-01

    The severe plastic deformation (SPD) method for joining dissimilar metal materials to obtain a multilayer hybrid material having an ultrafine or nanoscale structure was proposed. A nanostructured multilayer "0.08C-18Cr-0.5Ti steel/V-10Ti-5Cr alloy/0.08C-18Cr-0.5Ti steel" hybrid material was obtained by high-pressure torsion (HPT) at different temperatures. The analysis of the structure of the hybrid material and its components was carried out by the methods of transmission and scanning electron microscopies. The distribution of chemical elements in the cross section of the hybrid material was studied by X-ray microanalysis. The microhardness was measured to estimate the hybrid material hardening after HPT. Tight joint zones between the layers of the hybrid material were formed during HPT. The fragmentation of the steel and vanadium alloy layers was observed, and the "mixing" of the layers occurred after HPT at 293 K and 473 K (20 °C and 200 °C). A smoother interface between the layers was observed after HPT at 673 K (400 °C). The significant hardening (2.0 to 3.5×) of each layer of the hybrid material was observed as a result of HPT.

  12. Nature of active vanadium nanospecies in MCM-41 type catalysts for olefins oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Chanquía, Corina M., E-mail: cchanquia@cab.cnea.gov.ar [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Cánepa, Analía L. [Centro de Investigación y Tecnología Química (CITeQ), Universidad Tecnológica Nacional, Facultad Regional Córdoba (UTN-FRC), Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016, Córdoba Capital (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Winkler, Elin L. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); and others

    2016-06-01

    A multi-technique physicochemical investigation including UV–Vis-DRS, Raman spectroscopy, XPS, ESR and FTIRS with pyridine adsorption was performed to analyze the nature of different vanadium nanospecies present on MCM-41 type catalysts. By employing a direct hydrothermal synthesis, vanadium species were incorporated into siliceous structure mainly as tetrahedrally coordinated isolated V{sup δ+} ions, which would be located inside the wall and on the wall surface of the mesoporous channels. The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was also revealed. Acidity measurements permitted to infer about the majority presence of Lewis acid sites, which increase with vanadium content. The catalytic performance of these materials was evaluated in the reaction of α-pinene oxidation with H{sub 2}O{sub 2}. The highest intrinsic activity of the sample with lower V loading was attributed to the high dispersion and efficiency of the isolated V{sup δ+} species that actuate as active sites. A mixture of reaction products arising from competitive processes of epoxidation and allylic oxidation was found. - Highlights: • Nature of vanadium nanospecies in mesoporous silicates was investigated. • From hydrothermal sol–gel synthesis, isolated V{sup δ+} sites were mainly generated. • The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was revealed. • The catalytic performance was evaluated in α-pinene oxidation with H{sub 2}O{sub 2}. • The high catalytic activity is attributed to high dispersion of isolated V{sup δ+} ions.

  13. 77 FR 46712 - Ferrovanadium and Nitrided Vanadium From the Russian Federation: Negative Final Determination of...

    Science.gov (United States)

    2012-08-06

    ... are vanadium additives other than ferrovanadium and nitrided vanadium, such as vanadium-aluminum master alloys, vanadium chemicals, vanadium waste and scrap, vanadium-bearing raw materials, such as slag... the processing performed in the United States represents a small proportion of the value of the...

  14. Comparative analysis of niobium and vanadium carbide efficiency in the high energy mechanical milling of aluminum bronze alloy

    Directory of Open Access Journals (Sweden)

    Alexandre Nogueira Ottoboni Dias

    Full Text Available Abstract This study aims to analyze the efficiency of niobium and vanadium carbides in the high energy mechanical milling of aluminum bronze alloy. Two series of experiments were made following the same steps for both niobium carbide (NbC and vanadium carbide (VC additions: 30 g of chips were weighed and placed in a stainless steel jar with 3 % of carbide and 1 % of stearic acid for a mass/sphere relationship of 1:10. The milling was realized using a planetary ball mill for 10, 30 and 50 hours in an inert argon atmosphere at 300 rpm. Results shown in laser diffraction indicate a great reduction in the particle sizes of powders when VC is used. For 30 hours milling, D50 values ranged from 1580 µm with NbC to 182.3 µm with VC addition. The D50 values ranged from 251.5 µm with NbC to 52.26 µm with VC addition, for 50 hours milling. The scanning electron microscopy showed that in 10 hours of milling, the energy was not sufficient to achieve the shear of chips in both cases. For 30 hours, it's possible to observe particles with sizes between 100 µm and 800 µm with NbC addition while for the same milling time, with VC it's possible to see particles with different sizes, but with many shapes of fine particulates. For 50 hours milling, particles achieved the smaller sizes between 50 and 200 µm with NbC and ranging from 5 until 50 µm with VC addition.

  15. Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter

    The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...... and X-ray diffraction. Homogeneous VC mono-phase layers with Vickers hardness of more than 2400 HV were obtained. Hardening and tempering of the vanadized Vanadis 6 steel did not affect the VC layers....

  16. Effect of Mechanical Activation Treatment on the Recovery of Vanadium from Converter Slag

    Science.gov (United States)

    Xiang, Junyi; Huang, Qingyun; Lv, Xuewei; Bai, Chenguang

    2017-10-01

    The high roasting temperature and low leaching efficiency of vanadium from vanadium-bearing converter slag are regarded as the main factors significantly influencing the application of calcification roasting-acid leaching processes in the cleaner production of vanadium. In this study, a mechanical activation treatment was performed to enhance the extraction of vanadium from converter slag. The enhancement effects obtained from mechanical activation were comprehensively evaluated through indices such as the roasting temperature and leaching efficiency. The effects of mechanical activation time, roasting temperature, leaching temperature, solid to liquid ratio, particle size, and acid concentration on the leaching efficiency were investigated. Microstructure morphology and elemental analyses of the raw materials and leaching residue were also investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results demonstrated that the mechanical activation significantly decreased the optimum roasting temperature from 1173 K to 1073 K (900 °C to 800 °C) and increased the leaching efficiency from 86.0 to 90.9 pct.

  17. Antimicrobial activity of vanadium chloroperoxidase on planktonic Streptococcus mutans cells and Streptococcus mutans biofilms

    NARCIS (Netherlands)

    Hoogenkamp, M.A.; Crielaard, W.; ten Cate, J.M.; Wever, R.; Hartog, A.F.; Renirie, R.

    2009-01-01

    The aim of this study was to investigate the antimicrobial activity of vanadium chloroperoxidase (VCPO) reaction products on planktonic and biofilm cellsof Streptococcus mutans C180-2. Planktonic and biofilm cells were incubated in a buffered reaction mixture containing VCPO, halide (either chloride

  18. Deuterium retention in VPS-W coated vanadium alloy (V-4Cr-4Ti)

    Science.gov (United States)

    Ueda, Yoshio; Uekita, Kazuhiro; Oya, Makoto; Ohtsuka, Yusuke; Nagasaka, Takuya; Kasada, Ryuta; Kimura, Akihiko; Tokunaga, Tomonori; Yoshida, Naoaki

    2013-07-01

    D retention in a VPS W coated V alloy (V-4Cr-4Ti, NIFS Heat 2) was investigated by an ion beam irradiation with a HiFIT device. Irradiation temperature changed from 473 K to 773 K and ion fluence was 1024 m-2. In addition, during ion irradiation atmospheric pressure was 0.5 mTorr. It was found that ambient gas absorption was the dominant process for D retention. Ion irradiation could enhance gas absorption probably due to surface modification (oxide layer removal) and could produce ion induced trapping sites. Although these ion induced processes can be avoided by W coating layers, D retention is still significant for VPS-W coated V alloy. D trapping could be done mainly in V-alloy and its mechanisms could be related to some intrinsic defects in V alloy and formation of titanium hydride at elevated temperature.

  19. Thermal oxidation of vanadium-free Ti alloys: An X-ray photoelectron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Maria Francisca, E-mail: mflopez@icmm.csic.es [Department of Surfaces and Coatings, ICMM-CSIC, Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain); Gutierrez, Alejandro [Departamento de Fisica Aplicada and Instituto Nicolas Cabrera, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Jimenez, Jose Antonio [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo 8, E-28040 Madrid (Spain); Martinesi, Maria; Stio, Maria; Treves, Cristina [Department of Biochemical Sciences of University of Florence, Viale Morgagni 50, 50134 Florence (Italy)

    2010-04-06

    In the present work, X-ray photoelectron spectroscopy (XPS) was used to study the surface chemical composition of three alloys for biomedical applications: Ti-7Nb-6Al, Ti-13Nb-13Zr and Ti-15Zr-4Nb. The surface of these alloys was modified by annealing in air at 750 deg. C for different times with the aim of developing an oxide thick layer on top. The evolution of surface composition with annealing time was studied by XPS, and compared with the composition of the native oxide layer present on the samples before annealing. Two different oxidation trends were observed depending on the alloying elements and their corresponding diffusion kinetics, which give rise to different chemical species at the topmost layers. These results were linked with an evaluation of the biological response of the alloys by bringing them in contact with human peripheral blood mononuclear cells (PBMC).

  20. AFM and SEM characterization of non-toxic vanadium-free Ti alloys used as biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Morant, C.; Lopez, M.F.; Gutierrez, A.; Jimenez, J.A

    2003-12-30

    In this work, three titanium alloys have been studied by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM) to determine their surface topography. The alloys investigated were Ti-6Al-7Nb, Ti-13Nb-13Zr, and Ti-15Zr-4Nb, with no presence of the toxic element V, and with a possible use as biomaterials for osteoarticular prostheses. These alloys were studied at room temperature and also after a thermal treatment at 750 deg. C during 24 h, which produces a protective surface oxide layer. The aim of the present work is to compare the surface structure and morphology of the alloys, both as-received and after the oxide layer was formed at elevated temperature.

  1. Properties of electrochromic nickel-vanadium oxide films sputter-deposited from nonmagnetic alloy target

    Science.gov (United States)

    Avendano, Esteban; Azens, Andris; Niklasson, Gunnar A.

    2001-11-01

    In this study we investigate the structure, composition, diffusion coefficient, and electrochromic properties of nickel-vanadium oxide films as a function of deposition conditions. Polycrystalline films have been deposited by DC magnetron sputtering from a nonmagnetic target of Ni0.93V0.07 in an atmosphere of O2/Ar and Ar/O2/H2, with the gas flow ratios varied systematically to cover the range from nearly-metallic to overoxidized films. The results contradict the usual view that films deposited in O2/Ar are dark brown in their as-deposited state. While such films can easily be deposited, the optimum electrochromic properties have been observed at O2/Ar ratios giving nearly transparent films. Addition of hydrogen to the sputtering atmosphere improved cycling stability of the films. The diffusion coefficient has been determined by the Galvanostatic Intermittent Titration Technique (GITT).

  2. Evaluation of flow properties in the weldments of vanadium alloys using a novel indentation technique

    Energy Technology Data Exchange (ETDEWEB)

    Gubbi, A.N.; Rowcliffe, A.F.; Lee, E.H.; King, J.F.; Goodwin, G.M. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    Automated Ball Indentation (ABI) testing, was successfully employed to determine the flow properties of the fusion zone, heat affected zone (HAZ), and base metal of the gas tungsten arc (GTA) and electron beam (EB) welds of the V-4Cr-4Ti (large heat no. 832665) and the V-5Cr-5Ti (heat 832394) alloys. ABI test results showed a clear distinction among the properties of the fusion zone, HAZ, and base metal in both GTA and EB welds of the two alloys. GTA and EB welds of both V-4Cr-4Ti and V-5Cr-5Ti alloys show strengthening of both the fusion zone and the HAZ (compared to base metal) with the fusion zone having higher strength than the HAZ. These data correlate well with the Brinell hardness. On the other hand, GTA welds of both alloys, after a post-weld heat treatment of 950{degrees}C for 2 h, show a recovery of the properties to base metal values with V-5Cr-5Ti showing a higher degree of recovery compared to V-4Cr-4Ti. These measurements correlate with the reported recovery of the Charpy impact properties.

  3. Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium.

    Science.gov (United States)

    Donaldson, E M

    1970-07-01

    A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere.

  4. Density decrease in vanadium-base alloys irradiated in the dynamic helium charging experiment

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Galvin, T.M.; Smith, D.L. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    Combined effects of dynamically charged helium and neutron damage on density decrease (swelling) of V-4Cr-4Ti, V-5Ti, V-3Ti-1Si, and V-8Cr-6Ti alloys have been determined after irradiation to 18-31 dpa at 425-600{degrees}C in the Dynamic helium Charging Experiment (DHCE). To ensure better accuracy in density measurement, broken pieces of tensile specimens {approx} 10 times heavier than a transmission electron microscopy (TEM) disk were used. Density increases of the four alloys irradiated in the DHCE were <0.5%. This small change seems to be consistent with the negligible number density of microcavities characterized by TEM. Most of the dynamically produced helium atoms seem to have been trapped in the grain matrix without significant cavity nucleation or growth.

  5. Study of in-reactor creep of vanadium alloy in the HFIR RB-12J experiment

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Konicek, C.F.; Tsai, H. [Argonne National Lab., IL (United States)

    1996-10-01

    Biaxial creep specimens will be included in the HFIR RB-12J experiment to study in-reactor creep of the V-4Cr-4Ti alloy at {approx}500{degrees}C and 5 dpa. These specimens were fabricated with the 500-kg, heat (832665) material and pressurized to attain 0, 50, 100, 150, and 200 MPa mid-wall hoop stresses during the irradiation.

  6. Pseudogap state and strong scattering of current carriers by local spin moments as mechanisms for the semiconducting properties of near-stoichiometric iron-vanadium-aluminum alloys

    Science.gov (United States)

    Lonchakov, A. T.; Marchenkov, V. V.; Okulov, V. I.; Okulova, K. A.

    2013-01-01

    New experimental evidence is obtained on the physical nature of the semiconducting properties of Fe2-xV1+xAl alloys with near-stoichiometric (x = 0) compositions. We examine the low-temperature thermal emf of two alloys: one is enriched in vanadium and exhibits a pseudogap in the electron density of states at the Fermi energy, while in the other, which is depleted in vanadium, the scattering of electrons by localized spins has a stronger influence. The experimental temperature dependences of the thermal emf at low temperatures display some characteristic anomalies that are observed here for the first time and are manifestations of these two effects. Existing theory is used to interpret the anomalous contributions of both effects (types), determine their characteristic parameters, and establish the conditions under which they appear in V-depleted and V-enriched alloys. Data on the thermal emf in magnetic fields show that that the thermal emf decreases substantially as the magnetic field is increased, confirming the key role of the mechanism of current carrier scattering by localized moments.

  7. Hypoglycemic activity of fermented mushroom of Coprinus comatus rich in vanadium.

    Science.gov (United States)

    Han, Chunchao; Yuan, Junhua; Wang, Yingzi; Li, Lingjun

    2006-01-01

    The hypoglycemic activity of fermented mushroom of Coprinus comatus rich in vanadium (CCRV) was studied in this paper. Alloxan and adrenalin induced hyperglycemic mice were used in the study. The blood glucose and the HbA1c of the mice were analyzed, respectively. At the same time, the sugar tolerance of the normal mice was also determined. After the mice were administered (ig) with CCRV, the blood glucose and the HbA1c of alloxan-induced hyperglycemic mice decreased (p < 0.05, p < 0.01), ascension of blood glucose induced by adrenalin was inhibited (p < 0.01) and the sugar tolerance of the normal mice was improved. Also, the body weight of the alloxan-induced hyperglycemic mice was increased gradually. In the fermented mushroom of C. comatus, vanadium at lower doses in combination with C. comatus, induced significant decreases of the blood glucose and HbA1c levels in hyperglycemic mice.

  8. Bis(benzimidazole)amine vanadium catalysts for olefin polymerisation and co-polymerisation: thermally robust, single-site catalysts activated by simple alkylaluminium reagents.

    Science.gov (United States)

    Tomov, Atanas K; Gibson, Vernon C; Zaher, Damien; Elsegood, Mark R J; Dale, Sophie H

    2004-09-07

    Vanadium complexes containing bis(benzimidazole)amine ligands, upon activation by simple alkylaluminium reagents, give unusually robust, single-site, catalysts for olefin polymerisation/co-polymerisation.

  9. Irradiation-induced precipitation and mechanical properties of vanadium alloys at <430 C

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Gazda, J.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    Recent attention to V-base alloys has focused on the effect of low-temperature (<430 C) irradiation on tensile and impact properties of V-4Cr-4Ti. In previous studies, dislocation channeling, which causes flow localization and severe loss of work-hardening capability, has been attributed to dense, irradiation-induced precipitation of very fine particles. However, efforts to identify the precipitates were unsuccessful until now. In this study, analysis by transmission electron microscopy (TEM) was conducted on unalloyed V, V-5Ti, V-3Ti-1Si, and V-4Cr-4Ti specimens that were irradiated at <430 C in conventional and dynamic helium charging experiments. By means of dark-field imaging and selected-area-diffraction analysis, the characteristic precipitates were identified to be (V,Ti{sub 1{minus}x})(C,O,N). In V-3Ti-1Si, precipitation of (V,Ti{sub 1{minus}x})(C,O,N) was negligible at <430 C, and as a result, dislocation channeling did not occur and work-hardening capability was high.

  10. Thermally activated martensite formation in ferrous alloys

    DEFF Research Database (Denmark)

    Villa, Matteo; Somers, Marcel A. J.

    2017-01-01

    Magnetometry was applied to investigate the formation of α/α´martensite in 13ferrous alloys during immersion in boiling nitrogen and during re-heating to room temperature at controlled heating rates in the range 0.0083-0.83 K s-1. Data showsthat in 3 of the alloys, those that form {5 5 7}γ...... martensite, no martensite developsduring cooling. For all investigated alloys, irrespective of the type of martensiteforming, thermally activated martensite develops during heating. The activationenergy for thermally activated martensite formation is in the range 8‒27 kJ mol-1and increases with the fraction...... of interstitial solutes in the alloy...

  11. High efficiency of CO2-activated graphite felt as electrode for vanadium redox flow battery application

    Science.gov (United States)

    Chang, Yu-Chung; Chen, Jian-Yu; Kabtamu, Daniel Manaye; Lin, Guan-Yi; Hsu, Ning-Yih; Chou, Yi-Sin; Wei, Hwa-Jou; Wang, Chen-Hao

    2017-10-01

    A simple method for preparing CO2-activated graphite felt as an electrode in a vanadium redox flow battery (VRFB) was employed by the direct treatment in a CO2 atmosphere at a high temperature for a short period. The CO2-activated graphite felt demonstrates excellent electrochemical activity and reversibility. The VRFB using the CO2-activated graphite felts in the electrodes has coulombic, voltage, and energy efficiencies of 94.52%, 88.97%, and 84.15%, respectively, which is much higher than VRFBs using the electrodes of untreated graphite felt and N2-activated graphite felt. The efficiency enhancement was attributed to the higher number of oxygen-containing functional groups on the graphite felt that are formed during the CO2-activation, leading to improving the electrochemical behaviour of the resultant VRFB.

  12. Effect of alloying elements on the composition of carbide phases and mechanical properties of the matrix of high-carbon chromium-vanadium steel

    Science.gov (United States)

    Titov, V. I.; Tarasenko, L. V.; Utkina, A. N.

    2017-01-01

    Based on the results of phase physicochemical analysis of high-carbon chromium-vanadium steel, the predominant type of carbide that provides high wear resistance has been established, and its amount and amount of carbon in martensite have been determined. Data on the composition and the amount of carbide phase and on the chemical composition of the martensite of high-carbon steel have been obtained, which allows determination of the alloying-element concentration limits. The mechanical testing of heats of a chosen chemical composition has been carried out after quenching and low-temperature tempering. The tests have demonstrated benefits of new steel in wear resistance and bending strength with the fatigue strength being retained, compared to steels subjected to cementation. The mechanism of secondary strengthening of the steel upon high-temperature tempering has been revealed. High-temperature tempering can be applied to articles that are required to possess both high wear resistance and heat resistance.

  13. Tensile properties of vanadium-base alloys irradiated in the Fusion-1 low-temperature experiment in the BOR-60 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Gazda, J.; Nowicki, L.J.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    The irradiation has been completed and the test specimens have been retrieved from the lithium-bonded capsule at the Research Institute of Atomic Reactors (RIAR) in Russia. During this reporting period, the Argonne National Laboratory (ANL) tensile specimens were received from RIAR and initial testing and examination of these specimens at ANL has been completed. The results, corroborating previous findings showed a significant loss of work hardening capability in the materials. There appears to be no significant difference in behavior among the various heats of vanadium-base alloys in the V-(4-5)Cr-(4-5)Ti composition range. The variations in the preirradiation annealing conditions also produced no notable differences.

  14. Effect of vanadium on renal Na+,K+-ATPase activity in diabetic rats: a possible role of leptin.

    Science.gov (United States)

    Morsy, Mohamed D; Abdel-Razek, Hesham A; Osman, Osama M

    2011-03-01

    Several researches attempt to protect diabetic patients from the development of nephropathy. Involvement of leptin and renal Na+,K+-ATPase enzyme in diabetic nephropathy (DN) development is a recent field for researches. Vanadium, as a trace element with insulin mimetic effect, may act synergistically with insulin to protect against the development of DN. Sixty male Sprague Dawley rats were divided into six groups: control group (C), vanadium control group (CV), streptozotocin-induced diabetic group (D), insulin-treated diabetic group (DI), vanadium-treated diabetic group (DV), and combined insulin and vanadium-treated diabetic group. Six weeks later, systolic blood pressure (SBP) was measured and retro-orbital blood samples were collected to estimate glycosylated hemoglobin (HbA(₁c)), serum sodium (Na+) and creatinine, blood urea nitrogen (BUN) and plasma leptin levels. Preparation of microsomal fraction of renal tissue homogenate for estimation of Na+,K+-ATPase activity was done. The D group showed a significant increase in SBP, HbA(₁c), serum Na+, creatinine, and BUN levels and Na+,K+-ATPase activity in microsomal fraction of renal tissue homogenate while plasma leptin level decreased significantly compared with C and CV groups. Both DI and DV groups showed a significant improvement in all the above measured parameters compared with D group while there were no significant changes between the DI and DV groups. Concomitant treatment with insulin and vanadium resulted in a significant improvement in all the measured parameters compared to each alone. Vanadium in combination with insulin ameliorates DN markers and reduces renal Na+,K+-ATPase overactivity in diabetic rats. An effect that may be partially mediated through correction of hypoleptinemia observed in these animals.

  15. Effect of substitutions of tungsten, vanadium, molybdenum, and titanium for reduced niobium contents in Inconel Alloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, K.R.

    1985-01-01

    Inconel Alloy 718 is a nickel iron-base superalloy strengthened by the precipitation of the metastable Ni/sub 3/Nb-..gamma..'' phase. Large coherency strains between ..gamma..'' and the matrix result in a slow precipitation rate and an intermediate maximum use temperature. The combination of slow precipitation rate and the relative formability and machinability of Alloy 718 make it a popular material for the fabrication of superalloy components. The dependence on foreign sources of Nb has pointed out the desirability of reducing the Nb content of alloy 718 while maintaining the tensile and stress-rupture properties of the original alloys. The purpose of this investigation was to determine the effects of reduced Nb, and substitutions for Nb, on the properties of Alloy 718. A seris of alloys was developed having a base composition similar to Alloy 718, with reduced Nb levels of 3.00 and 1.10 wt% Nb. Substitutions of 3.0% W, 3.0W + 0.9V or Mo increased from 3.0 to 5.8% were made for the Nb in these alloys. Two additional alloys, one containing 3.49% Nb and 1.10% Ti and another containing 3.89% Nb and 1.27% Ti, were also studied. Solution and age heat treatments were optimized for each alloy to develop a proper microstructure. The reduction in Nb content required the substitution of other elements to maintain the properties of the original alloy. Additions of solid-solution elements to a reduced Nb alloy had no significant effect on the properties of the alloys under either process condition.

  16. Influence of Vanadium 4+ and 5+ Ions on the Differentiation and Activation of Human Osteoclasts

    Directory of Open Access Journals (Sweden)

    Matthias A. König

    2017-01-01

    Full Text Available Background. In the pathophysiology of implant failure, metal ions and inflammation-driven osteoclasts (OC play a crucial role. The aim of this study was to investigate whether vanadium (V ions induce differentiation of monocytic OC precursors into osteoresorptive multinucleated cells. In addition, the influence of V ions on the activation and function of in vitro generated OC was observed. Methods. Human monocytes and osteoclasts were isolated from peripheral blood monocytic cells (PBMCs. Exposition with increasing concentrations (0–3 μM of V4+/V5+ ions for 7 days followed. Assessment of OC differentiation, cell viability, and resorptional ability was performed by standard colorimetric cell viability assay 3-(4,5-dimethylthiazol-2-yl-5-(3-carboxymethoxyphenyl-2-(4-sulfophenil-2H-tetrazolium (MTS, tartrate-resistant acid phosphatase (TRAP expression, and functional resorption assays on bone slides during a period of 21 days. Results. No significant differences were noted between V4+/V5+ ions (p>0.05. MTS showed significant reduction in cellular viability by V concentrations above 3 μM (p<0.05. V concentrations above 0.5 μM showed negative effects on OC activation/differentiation. Higher V concentrations showed negative effects on resorptive function (all p<0.05 without affecting cell viability. V4+/V5+ concentrations below 3 μM have negative effects on OC differentiation/function without affecting cell survival. Conclusion. Vanadium-containing implants may reduce implant failure rate by influencing osteoclast activity at the bone-implant interface. V-ligand complexes might offer new treatment options by accumulating in the bone.

  17. Influence of Vanadium 4+ and 5+ Ions on the Differentiation and Activation of Human Osteoclasts.

    Science.gov (United States)

    König, Matthias A; Gautschi, Oliver P; Simmen, Hans-Peter; Filgueira, Luis; Cadosch, Dieter

    2017-01-01

    In the pathophysiology of implant failure, metal ions and inflammation-driven osteoclasts (OC) play a crucial role. The aim of this study was to investigate whether vanadium (V) ions induce differentiation of monocytic OC precursors into osteoresorptive multinucleated cells. In addition, the influence of V ions on the activation and function of in vitro generated OC was observed. Human monocytes and osteoclasts were isolated from peripheral blood monocytic cells (PBMCs). Exposition with increasing concentrations (0-3 μM) of V4(+)/V5(+) ions for 7 days followed. Assessment of OC differentiation, cell viability, and resorptional ability was performed by standard colorimetric cell viability assay 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenil)-2H-tetrazolium (MTS), tartrate-resistant acid phosphatase (TRAP) expression, and functional resorption assays on bone slides during a period of 21 days. No significant differences were noted between V4(+)/V5(+) ions (p > 0.05). MTS showed significant reduction in cellular viability by V concentrations above 3 μM (p < 0.05). V concentrations above 0.5 μM showed negative effects on OC activation/differentiation. Higher V concentrations showed negative effects on resorptive function (all p < 0.05) without affecting cell viability. V4(+)/V5(+) concentrations below 3 μM have negative effects on OC differentiation/function without affecting cell survival. Vanadium-containing implants may reduce implant failure rate by influencing osteoclast activity at the bone-implant interface. V-ligand complexes might offer new treatment options by accumulating in the bone.

  18. Formation of vanadium carbide precipitations at the surface of alloys: Thermodynamics and kinetics aspects; Bildung von Vanadiumcarbid-Ausscheidungen auf Legierungsoberflaechen: Thermodynamische und kinetische Aspekte

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.; Uebing, C. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    The paper describes the formation of vanadium carbides on the surface layers of Fe-3%V-C(100) alloys. The phase diagram calculated for this alloyed material using the ThermoCalc program package reveals a co-existence of ferritic matrix and V{sub 3}C{sub 2} at temperatures of T{<=}650 C. This carbide is instable at elevated temperatures, leading to co-existence of ferrite and the cubic VC{sub 1-x}. Experimental analyses revealed the formation of a 2D VC compound in the top layers of the surface of Fe-3%V-C(100) alloys, induced by equilibrium segregation. The paper explains the usefulness of thermodynamic and kinetic calculations for interpretation of precipitation phenomena in steels. Mathematically derived and experimental results of analyses for the case of non-equilibrium segregation showed excellent agreement in the determination of carbide thickness (nanometer scale) and time dependence of segregation under fast cooling conditions. (orig./CB) [Deutsch] In der vorliegenden Arbeit wurde die Bildung von Vanadiumcarbiden auf Fe-3%V-C(100)-Legierungsoberflaechen beschrieben. Das anhand des ThermoCalc-Programmpakets fuer diese Legierungszusammensetzung berechnete Phasendiagramm zeigt bei niedrigen Temperaturen T{<=}650 C die Koexistenz von ferritischer Matrix und V{sub 3}C{sub 2}. Bei hoeheren Temperaturen ist dieses Carbid instabil und es liegt Koexistenz von Ferrit und dem kubischen VC{sub 1-x} vor. Die experimentellen Untersuchungen zeigen die Ausbildung einer zweidimensionalen VC-Oberflaechenverbindung auf Fe-3%V-C(100)-Legierungsoberflaechen durch Gleichgewichtssegregation. Diese Arbeit zeigt, dass thermodynamische und kinetische Rechnungen bei der Deutung von Ausscheidungsphaenomenen in Staehlen sinnvoll eingesetzt werden koennen. Bei der Nichtgleichgewichtssegregation wurde bezueglich Carbiddicke (im Nanometerbereich) und Zeitabhaengigkeit der Ausscheidung bei schneller Abkuehlung eine hervorragende Uebereinstimmung zwischen Simulation und Experiment gefunden

  19. Effects of as-cast and wrought Cobalt-Chrome-Molybdenum and Titanium-Aluminium-Vanadium alloys on cytokine gene expression and protein secretion in J774A.1 macrophages

    DEFF Research Database (Denmark)

    Jakobsen, Stig Storgaard; Larsen, Agnete; Stoltenberg, Meredin

    2007-01-01

    to the metal implant and wear-products. The aim of the present study was to compare surfaces of as-cast and wrought Cobalt-Chrome-Molybdenum (CoCrMo) alloys and Titanium-Aluminium-Vanadium (TiAlV) alloy when incubated with mouse macrophage J774A.1 cell cultures. Changes in pro- and anti-inflammatory cytokines...... transcription, the chemokine MCP-1 secretion, and M-CSF secretion by 77%, 36%, and 62%, respectively. Furthermore, we found that reducing surface roughness did not affect this reduction. The results suggest that as-cast CoCrMo alloy is more inert than wrought CoCrMo and wrought TiAlV alloys and could prove...

  20. Amorphous Cobalt Vanadium Oxide as a Highly Active Electrocatalyst for Oxygen Evolution.

    Science.gov (United States)

    Liardet, Laurent; Hu, Xile

    2018-01-05

    The water-splitting reaction provides a promising mechanism to store renewable energies in the form of hydrogen fuel. The oxidation half-reaction, the oxygen evolution reaction (OER), is a complex four-electron process that constitutes an efficiency bottleneck in water splitting. Here we report a highly active OER catalyst, cobalt vanadium oxide. The catalyst is designed on the basis of a volcano plot of metal-OH bond strength and activity. The catalyst can be synthesized by a facile hydrothermal route. The most active pure-phase material ( a- CoVO x ) is X-ray amorphous and provides a 10 mA cm -2 current density at an overpotential of 347 mV in 1 M KOH electrolyte when immobilized on a flat substrate. The synthetic method can also be applied to coat a high-surface-area substrate such as nickel foam. On this three-dimensional substrate, the a- CoVO x catalyst is highly active, reaching 10 mA cm -2 at 254 mV overpotential, with a Tafel slope of only 35 mV dec -1 . This work demonstrates a- CoVO x as a promising electrocatalyst for oxygen evolution and validates M-OH bond strength as a practical descriptor in OER catalysis.

  1. Response of soil microbial activities and microbial community structure to vanadium stress.

    Science.gov (United States)

    Xiao, Xi-Yuan; Wang, Ming-Wei; Zhu, Hui-Wen; Guo, Zhao-Hui; Han, Xiao-Qing; Zeng, Peng

    2017-08-01

    High levels of vanadium (V) have long-term, hazardous impacts on soil ecosystems and biological processes. In the present study, the effects of V on soil enzymatic activities, basal respiration (BR), microbial biomass carbon (MBC), and the microbial community structure were investigated through 12-week greenhouse incubation experiments. The results showed that V content affected soil dehydrogenase activity (DHA), BR, and MBC, while urease activity (UA) was less sensitive to V stress. The average median effective concentration (EC50) thresholds of V were predicted using a log-logistic dose-response model, and they were 362mgV/kg soil for BR and 417mgV/kg soil for DHA. BR and DHA were more sensitive to V addition and could be used as biological indicators for soil V pollution. According to a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis, the structural diversity of the microbial community decreased for soil V contents ranged between 254 and 1104mg/kg after 1 week of incubation. As the incubation time increased, the diversity of the soil microbial community structure increased for V contents ranged between 354 and 1104mg/kg, indicating that some new V-tolerant bacterial species might have replicated under these conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Vanadium recycling in the United States in 2004

    Science.gov (United States)

    Goonan, Thomas G.

    2011-01-01

    As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the flow of vanadium in the U.S. economy in 2004. This report includes a description of vanadium supply and demand in the United States and illustrates the extent of vanadium recycling and recycling trends. In 2004, apparent vanadium consumption, by end use, in the United States was 3,820 metric tons (t) in steelmaking and 232 t in manufacturing, of which 17 t was for the production of superalloys and 215 t was for the production of other alloys, cast iron, catalysts, and chemicals. Vanadium use in steel is almost entirely dissipative because recovery of vanadium from steel scrap is chemically impeded under the oxidizing conditions in steelmaking furnaces. The greatest amount of vanadium recycling is in the superalloy, other-alloy, and catalyst sectors of the vanadium market. Vanadium-bearing catalysts are associated with hydrocarbon recovery and refining in the oil industry. In 2004, 2,850 t of vanadium contained in alloy scrap and spent catalysts was recycled, which amounted to about 44 percent of U.S. domestic production. About 94 percent of vanadium use in the United States was dissipative (3,820 t in steel/4,050 t in steel+fabricated products).

  3. Extraction spectrophotometric determination of vanadium in natural waters and aluminium alloys using pyridyl azo resorcinol (PAR) and iodo-nitro-tetrazolium chloride (INT).

    Science.gov (United States)

    Gavazov, K; Simeonova, Z; Alexandrov, A

    2000-06-30

    Extraction-spectrophotometric methods are developed for the determination of vanadium content in natural waters and aluminium alloys. They are based on the formation and subsequent extraction into chloroform of the ternary ion association complex of V(V) with PAR and INT in the presence of CDTA and NH(4)F as masking agents. Optimum pH range of the reaction is 5.5-7.5. Maximum absorbance of the extracted complex is at 560 nm. The method for determination of V(V) in drinking waters can be successfully applied at a concentration level of 3 ppb and higher without additional pre-concentration. Among studied more than 30 foreign ions potentially present in natural waters only Ca(II) can interfere. It is removed by precipitation as CaF(2) and filtration. A 40-fold excess of V(IV) does not interfere with determination of V(V) and can also be determined indirectly (after oxidation to V(V)). The proposed method is applied to analysis of model mixtures as well as to the analysis of tap and mineral waters. Beer's law is obeyed for up to 15 mug of V(V) in 40 ml aqueous phase. The accuracy and precision are reasonable. The RSD is in the range 6.5-23.2% for determination of 6.3 ppb V(V). The procedure for analysis of aluminium alloys differs from the procedure for analysis of waters by the order of introduction of the reagents. The macrocomponent does not interfere and is not separated. Mg, Mn, Cu, Zn, Fe, Cr, Ti and Zr do not interfere. A 25-fold excess of Ni interferes. The method is tested in the analysis of reference standards containing 0.005 and 0.007% V, respectively. The RSD is 1.4%.

  4. Graphene?Nanowall?Decorated Carbon Felt with Excellent Electrochemical Activity Toward VO2 +/VO2+ Couple for All Vanadium Redox Flow Battery

    OpenAIRE

    Li, Wenyue; Zhang, Zhenyu; Tang, Yongbing; Bian, Haidong; Ng, Tsz?Wai; Zhang, Wenjun; Lee, Chun?Sing

    2015-01-01

    3D graphene?nanowall?decorated carbon felts (CF) are synthesized via an in situ microwave plasma enhanced chemical vapor deposition method and used as positive electrode for vanadium redox flow battery (VRFB). The carbon fibers in CF are successfully wrapped by vertically grown graphene nanowalls, which not only increase the electrode specific area, but also expose a high density of sharp graphene edges with good catalytic activities to the vanadium ions. As a result, the VRFB with this novel...

  5. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D - Annual report input for 1996

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-10-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor (RD) upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy has been completed at Teledyne Wah Chang of Albany, Oregon (TWCA) to provide {approximately}800-kg of applicable product forms, and two billets have been extruded from the ingot. Chemical compositions of the ingot and both extruded billets were acceptable. Material from these billets will be converted into product forms suitable for components of the DIII-D Radiative Divertor structure. Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RD Program, and research into several joining methods for fabrication of the RD components, including resistance seam, friction, and electron beam welding, is continuing. Preliminary trials have been successful in the joining of V-alloy to itself by electron beam, resistance, and friction welding processes and to Inconel 625 by friction welding.

  6. Tensile and impact properties of vanadium-base alloys irradiated at low temperatures in the ATR-A1 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Nowicki, L.J.; Billone, M.C.; Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-03-01

    Subsize tensile and Charpy specimens made from several V-(4-5)Cr-(4-5)Ti alloys were irradiated in the ATR-A1 experiment to study the effects of low-temperature irradiation on mechanical properties. These specimens were contained in lithium-bonded subcapsules and irradiated at temperatures between {approx}200 and 300 C. Peak neutron damage was {approx}4.7 dpa. Postirradiation testing of these specimens has begun. Preliminary results from a limited number of specimens indicate a significant loss of work-hardening capability and dynamic toughness due to the irradiation. These results are consistent with data from previous low-temperature neutron irradiation experiments on these alloys.

  7. Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

    Science.gov (United States)

    Stavinoha, Joe N.

    The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al

  8. Investigation of activation cross-sections of deuteron induced reactions on vanadium up to 40 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Tarkanyi, F. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Ditroi, F., E-mail: ditroi@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Takacs, S. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Hermanne, A. [Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), Brussels (Belgium); Baba, M. [Cyclotron Radioisotope Center (CYRIC), Tohoku University, Sendai (Japan); Ignatyuk, A.V. [Institute of Physics and Power Engineering (IPPE), Obninsk (Russian Federation)

    2011-08-01

    Experimental excitation functions for deuteron induced reactions up to 40 MeV on natural vanadium were measured with the activation method using a stacked foil irradiation technique. From high resolution gamma spectrometry cross-section data for the production of {sup 51}Cr, {sup 48}V, {sup 48,47,46}Sc and {sup 47}Ca were determined. Comparisons with the earlier published data are presented and results for values predicted by different theoretical codes are included. Thick target yields were calculated from a fit to our experimental excitation curves and compared with the earlier experimental data. Depth distribution curves used for thin layer activation (TLA) are also presented.

  9. Activated Carbon Fiber Paper Based Electrodes with High Electrocatalytic Activity for Vanadium Flow Batteries with Improved Power Density.

    Science.gov (United States)

    Liu, Tao; Li, Xianfeng; Xu, Chi; Zhang, Huamin

    2017-02-08

    Vanadium flow batteries (VFBs) have received high attention for large-scale energy storage due to their advantages of flexibility design, long cycle life, high efficiency, and high safety. However, commercial progress of VFBs has so far been limited by its high cost induced by its low power density. Ultrathin carbon paper is believed to be a very promising electrode for VFB because it illustrates super-low ohmic polarization, however, is limited by its low electrocatalytic activity. In this paper, a kind of carbon paper (CP) with super-high electrocatalytic activity was fabricated via a universal and simple CO2 activation method. The porosity and oxygen functional groups can be easily tuned via this method. The charge transfer resistance (denoting the electrochemical polarization) of a VFB with CP electrode after CO2 activation decreased dramatically from 970 to 120 mΩcm2. Accordingly, the energy efficiency of a VFB with activated carbon paper as the electrode increased by 13% as compared to one without activation and reaches nearly 80% when the current density is 140 mAcm-2. This paper provides an effective way to prepare high-performance porous carbon electrodes for VFBs and even for other battery systems.

  10. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    Science.gov (United States)

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Six-coordinate oxo-vanadium(V) dimer complex with methoxy bridging: synthesis, crystal structure, biological activity and molecular docking

    Czech Academy of Sciences Publication Activity Database

    Heidari, F.; Fatemi, S.J.A.; Yousef Ebrahimipour, S.; Ebrahimnejad, H.; Castro, J.; Dušek, Michal; Eigner, Václav

    2017-01-01

    Roč. 76, Feb (2017), s. 1-4 ISSN 1387-7003 R&D Projects: GA ČR(CZ) GA14-03276S EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510; European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : oxo-vanadium(V) * Schiff base complex * antimicrobial activity * X-ray crystal structure Subject RIV: CA - Inorganic Chemistry Impact factor: 1.640, year: 2016

  12. Activation cross-sections of proton induced reactions on vanadium in the 37-65 MeV energy range

    OpenAIRE

    Ditrói, F.; Tárkányi, F.; Takács, S.; Hermanne, A.

    2016-01-01

    Experimental excitation functions for proton induced reactions on natural vanadium in the 37-65 MeV energy range were measured with the activation method using a stacked foil irradiation technique. By using high resolution gamma spectrometry cross-section data for the production of $^{51,48}$Cr, $^{48}$V, $^{48,47,46,44m,44g,43}$Sc and $^{43,42}$K were determined. Comparisons with the earlier published data are presented and results predicted by different theoretical codes (EMPIRE and TALYS) ...

  13. Activation cross-sections of proton induced reactions on vanadium in the 37–65 MeV energy range

    Energy Technology Data Exchange (ETDEWEB)

    Ditrói, F., E-mail: ditroi@atomki.hu [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Tárkányi, F.; Takács, S. [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Hermanne, A. [Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), Brussels (Belgium)

    2016-08-15

    Highlights: • Proton induced nuclear reactions on natural vanadium in the 35–65 MeV range. • Stacked foil irradiation technique. • Comparison of results with the EMPIRE and TENDL-2015 calculations. • Application of results in thin layer activation is demonstrated. - Abstract: Experimental excitation functions for proton induced reactions on natural vanadium in the 37–65 MeV energy range were measured with the activation method using a stacked foil irradiation technique. By using high resolution gamma spectrometry cross-section data for the production of {sup 51,48}Cr, {sup 48}V, {sup 48,47,46,44m,44g,43}Sc and {sup 43,42}K were determined. Comparisons with the earlier published data are presented and results predicted by different theoretical codes (EMPIRE and TALYS) are included. Thick target yields were calculated from a fit to our experimental excitation curves and compared with the earlier experimental yield data. Depth distribution curves to be used for thin layer activation (TLA) are also presented.

  14. Differential responses of osteoblast lineage cells to nanotopographically-modified, microroughened titanium-aluminum-vanadium alloy surfaces.

    Science.gov (United States)

    Gittens, Rolando A; Olivares-Navarrete, Rene; McLachlan, Taylor; Cai, Ye; Hyzy, Sharon L; Schneider, Jennifer M; Schwartz, Zvi; Sandhage, Kenneth H; Boyan, Barbara D

    2012-12-01

    Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Rechargeable lithium cells with modified vanadium oxide cathodes

    Science.gov (United States)

    Chung, S. K.; Chmilenko, N. A.; Borovykov, A. Ya; Lee, S. H.

    Modified vanadium oxide has been prepared by melting V 2O 5 with additives of 3-3.5% of sodium orthosilicate at 690°C for 3 h followed by fast cooling to an ambient temperature. Charge-discharge characteristics of this oxide were studied as an active cathode material for lithium secondary batteries. The oxide undergoes irreversible transition to become essentially amorphous after first discharge to cut-off voltage of 2 V vs. Li, and then exhibits excellent rechargeability in the 1.5 to 3.9 V potential range. The coin type 2325 size secondary cells have been manufactured and tested with the modified vanadium oxide cathodes and Li-Al alloy anodes. Preliminary shallow cycling modifies the cells' performance and allows to obtain rating capacity 50 mA h in the voltage diapason of 2.0-3.9 V with draining current 0.5 mA.

  16. Superposition of nanostructures on microrough titanium–aluminum–vanadium alloy surfaces results in an altered integrin expression profile in osteoblasts

    Science.gov (United States)

    Gittens, Rolando A.; Olivares-Navarrete, Rene; Hyzy, Sharon L.; Sandhage, Kenneth H.; Schwartz, Zvi; Boyan, Barbara D.

    2014-01-01

    Recent studies of new surface modifications that superimpose well-defined nanostructures on microrough implants, thereby mimicking the hierarchical complexity of native bone, report synergistically enhanced osteoblast maturation and local factor production at the protein level compared to growth on surfaces that are smooth, nanorough, or microrough. Whether the complex micro/nanorough surfaces enhance the osteogenic response by triggering similar patterns of integrin receptors and their associated signaling pathways as with well-established microrough surfaces, is not well understood. Human osteoblasts (hOBs) were cultured until confluent for gene expression studies on tissue culture polystyrene (TCPS) or on titanium alloy (Ti6Al4V) disks with different surface topographies: smooth, nanorough, microrough, and micro/nanorough surfaces. mRNA expression of osteogenesis-related markers such as osteocalcin (BGLAP) and bone sialoprotein (BSP), bone morphogenetic protein 2 (BMP2), BMP4, noggin (NOG) and gremlin 1 (GREM1) were all higher on microrough and micro/nanorough surfaces, with few differences between them, compared to smooth and nanorough groups. Interestingly, expression of integrins α1 and β2, which interact primarily with collagens and laminin and have been commonly associated with osteoblast differentiation on microrough Ti and Ti6Al4V, were expressed at lower levels on micro/nanorough surfaces compared to microrough ones. Conversely, the av subunit, which binds ligands such as vitronectin, osteopontin, and bone sialoprotein among others, had higher expression on micro/nanorough surfaces concomitantly with regulation of the β3 mRNA levels on nanomodified surfaces. These results suggest that the maturation of osteoblasts on micro/nanorough surfaces may be occurring through different integrin engagement than those established for microrough-only surfaces. PMID:25158204

  17. [The vanadium compounds: chemistry, synthesis, insulinomimetic properties].

    Science.gov (United States)

    Fedorova, E V; Buriakina, A V; Vorob'eva, N M; Baranova, N I

    2014-01-01

    The review considers the biological role of vanadium, its participation in various processes in humans and other mammals, and the anti-diabetic effect of its compounds. Vanadium salts have persistent hypoglycemic and antihyperlipidemic effects and reduce the probability of secondary complications in animals with experimental diabetes. The review contains a detailed description of all major synthesized vanadium complexes having antidiabetic activity. Currently, vanadium complexes with organic ligands are more effective and safer than the inorganic salts. Despite the proven efficacy of these compounds as the anti-diabetic agents in animal models, only one organic complex of vanadium is currently under the second phase of clinical trials. All of the considered data suggest that vanadium compound are a new promising class of drugs in modern pharmacotherapy of diabetes.

  18. Aluminothermic production of titanium alloys (Part 2: Impact of activated rutile on process sustainability

    Directory of Open Access Journals (Sweden)

    S. Hassan-Pour

    2015-06-01

    Full Text Available The aluminothermic process provides a cost-reduced production method for titanium and titanium alloys by reduction of TiO2 with subsequent refining by electroslag remelting The aluminothermy involves high heating rates, high temperatures and short reactions times combined with a self-propagating behaviour of the reaction. By co-reduction of TiO2 and oxides of alloying elements such as vanadium pentoxide, direct synthesis of a titanium alloy is possible. The use of rutile ore concentrates causes a further reduction of process steps. In order to charge rutile ore complex thermodynamic calculations are required taking enthalpy input of various bycomponents into account. The aluminothermic reduction is conventionally enhanced by a highly heatproviding reaction based on the reduction of KClO4. In order to minimize the use of chlorine-based products extensive studies are made to investigate the feasibility of using mechanically activated rutile as input material for the aluminothermic process. Due to the mechanical activation the intrinsic enthalpy of the reaction is increased thus facilitates a process with reduced amount of KClO4. A major challenge represents the determination of a compromise between low activation duration and reduced KClO4 amount. In order to define the process window parameters like intrinsic chemical energy (enthalpy of the reaction mixture, equilibrium temperature and physical properties (particle size and mixing degree were optimized. After adjusting the process parameters it is possible to save up to 42 % KClO4 for the ATR reaction with 2h activated input material. This reduction of KClO4 material affects a decrease of the produced gaseous compounds and the subsequent off-gas cleaning system.

  19. Reduced Activation W Alloys for Plasma Facing Materials

    Energy Technology Data Exchange (ETDEWEB)

    Waseem, Owais Ahmed; Kim, Seung Su; Lee, Jun Ho; Hong, Soon Hyung; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    In order to improve the in-service characteristics of W, thorough research on W-based composites, new W alloys and functionally graded materials are in progress. The limitations of conventional W alloys such as such as high brittleness, high activation energy for dislocation's mobility, reduced mechanical strength due to reaction phases, poor fabricability, defective passive layer, poor workability and unavailability of good number of alloy systems have persuaded us to divert research focus towards W-based high entropy alloys. The core effects of high entropy alloys include enhanced mixing entropy, sluggish diffusion, severe lattice distortion and cocktail effects. These key characteristics of high entropy alloys promote the formation of solid solution of 5 to 13 principle elements with exceptionally high strength, hardness, thermal stability, wear resistance, fatigue and creep resistance. Although the synthesis and exploitation of high entropy alloys have been in progress, this study comprises of our work in which we developed a reduced activation W-based high entropy alloy by not incorporating Mo, Cu, Nb and by reducing Ti content. In this research a powder metallurgical technique has been successfully used for producing novel W-based alloy with enhanced mechanical properties. An undiscovered potential of an unusual and so far disregarded powder metallurgical technique i. e. simple mixing in the development of W based material for future fusion power plants has been exploited by fabricating and analyzing a novel tungsten based high entropy alloy system x%W-(100-x)/4%(TaTiCrV). The characterization of HEA samples by XRD showed BCC crystal structure of the alloys. Microstructural examination SEM-EDS revealed the presence of bright and dark regions as W and Ti-rich phases, respectively. The evaluation of microstructures by using image processing software and Vickers hardness via micro-Vickers hardness tester showed the similar dependency of phase fraction and

  20. The future of/for vanadium.

    Science.gov (United States)

    Rehder, Dieter

    2013-09-07

    Vanadium compounds are stored or employed by several groups of bacterial and eukaryotic organisms. Two types of vanadium-dependent enzymes have so far been characterised: vanadate-dependent haloperoxidases from fungi, lichens, marine macroalgae and Streptomyces bacteria, and vanadium nitrogenases in proteo- and cyanobacteria. Several bacterial strains can employ vanadate(V) as an external electron acceptor in respiration, reducing vanadate to VO(2+) and thus contributing to the mineralisation of vanadium and to the detoxification of vanadate-contaminated water. Amanita mushrooms and many sea squirts accumulate vanadium, without the importance of this practise being well understood. Further, the analogy between vanadate and phosphate implicates an interference of vanadate with metabolic processes involving phosphate, suggesting a regulatory role for vanadate in most if not all organisms, including humans, but also hinting at toxic effects at unphysiologically high vanadate concentrations. The antidiabetic effect of vanadium compounds is probably related to the phosphate-vanadate antagonism, as is the potentiality of vanadate in the amelioration of cardiovascular affliction. The anti-cancer action of vanadium compounds and their in vitro activity towards the protozoa causing amoebiasis, leishmaniasis and Chagas' disease again may be rooted in the intervention of vanadate with the activity of phosphatases and kinases. In addition, most likely the ability of vanadate(V) and oxidovanadium(IV) to regulate the cellular production of reactive oxygen species comes in, thus influencing cellular signalling. Future developments of vanadium chemistry are likely to emphasize topics related to biological, environmental and medicinal aspects. Condensation of monovanadate results in the formation of oligovanadates, polyvanadates and finally colloidal and solid vanadium oxides that, in part, convey bio-mimetic functions comparable to those of simple vanadate, including its catalytic

  1. In Vitro Antitumor Activity of a Keggin Vanadium-Substituted Polyoxomolybdate and Its ctDNA Binding Properties

    Directory of Open Access Journals (Sweden)

    Wen Qi

    2015-01-01

    Full Text Available A Keggin vanadium-substituted polyoxomolybdate, K5PMo10V2O40 (PMo10V2, has been synthesized and it’s antitumor effect against Hela cells was investigated. The calf thymus DNA (ctDNA binding ability of PMo10V2 was also evaluated by UV-Vis absorption spectra and fluorescence spectra. The identity and high purity of PMo10V2 was confirmed by elemental analysis and IR analysis. And the antitumor activity test of PMo10V2 was carried out on Hela cancer cells line by MTT assay. The results of MTT assay show that PMo10V2 significantly reduced the viability of Hela cells in a dose-dependent manner and exhibited stronger inhibitory activity against Hela cells at an IC50 of 800 μg/mL, which is more effective than the positive control, 5-Fu (P<0.05. The results of the UV-Vis absorption spectra and fluorescence spectra indicated the groove or outside stacking binding between PMo10V2 and ctDNA. These results show that the antitumor activity of PMo10V2 may be caused by the interactions between DNA and PMo10V2.

  2. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    Directory of Open Access Journals (Sweden)

    Guosong Sun

    2016-03-01

    Full Text Available Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD, N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhile, the catalytic activity of VOx/MSU-1 was investigated, and VOx/MSU-1 with 12.0 wt. % VOx content was found to be the best one, with the conversion of isobutane (58.8% and the selectivity of isobutene (78.5% under the optimal reaction conditions. In contrast with the reaction in the absence of CO2, the presence of CO2 in the reaction stream could obviously enhance the isobutane dehydrogenation, which raised the conversion of reaction and the stability of VOx/MSU-1.

  3. Adhesion, activation, and aggregation of blood platelets and biofilm formation on the surfaces of titanium alloys Ti6Al4V and Ti6Al7Nb.

    Science.gov (United States)

    Walkowiak-Przybyło, M; Klimek, L; Okrój, W; Jakubowski, W; Chwiłka, M; Czajka, A; Walkowiak, B

    2012-03-01

    Titanium alloys are still on the top list of fundamental materials intended for dental, orthopedics, neurological, and cardiovascular implantations. Recently, a special attention has been paid to vanadium-free titanium alloy, Ti6Al7Nb, that seems to represent higher biocompatibility than traditional Ti6Al4V alloy. Surprisingly, these data are not thoroughly elaborated in the literature; particularly there is a lack of comparative experiments conducted simultaneously and at the same conditions. Our study fills these shortcomings in the field of blood contact and microbiological colonization. To observe platelets adhesion and biofilm formation on the surfaces of compared titanium alloys, fluorescence microscope Olympus GX71 and scanning electron microscope HITACHI S-3000N were used. Additionally, flow cytometry analysis of platelets aggregation and activation in the whole blood after contact with sample surface, as an essential tool for biomaterial thrombocompatibility assessment, was proposed. As a result of our study it was demonstrated that polished surfaces of Ti6Al7Nb and Ti6Al4V alloys after contact with whole citrated blood and E. coli bacterial cells exhibit a considerable difference. Overall, it was established that Ti6Al4V has distinct tendency to higher thrombogenicity, more excessive bacterial biofilm formation and notable cytotoxic properties in comparison to Ti6Al7Nb. However, we suggest these studies should be extended for other types of cells and biological objects. Copyright © 2012 Wiley Periodicals, Inc.

  4. Microadditions of boron and vanadium in ADI

    Directory of Open Access Journals (Sweden)

    Rzychoń T.

    2007-01-01

    Full Text Available In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI. Melts were conducted with iron-nickel-magnesium master alloy. Thermal analysis of the solidification process of the cast keel blocks was conducted, the heat treatment of the alloys was carried out, and then the effect of the introduced additions of boron and vanadium on the hardenability of the investigated cast iron was examined and evaluated.

  5. Lead activity in Pb-Sb-Bi alloys

    Directory of Open Access Journals (Sweden)

    A. S. Kholkina

    2014-11-01

    Full Text Available The present work is devoted to the study of lead thermodynamic activity in the Pb-Sb-Bi alloys. The method for EMF measurements of the concentration cell: (–Pb|KCl-PbCl2¦¦KCl-PbCl2|Pb-(Sb-Bi(+ was used. The obtained concentration dependences of the galvanic cell EMF are described by linear equations. The lead activity in the ternary liquid-metal alloy demonstrates insignificant negative deviations from the behavior of ideal solutions.

  6. Dependence of Vanadium Recovery

    African Journals Online (AJOL)

    a large-scale vanadium processing or separation processes where vanadium is a contaminant. However, the ... in a separating funnel, swirled manually and later on a mechanical shaker operated at 120 rpm for 2 minutes ..... (40% v/v) TBP and the relevant scheme for extraction would be according to Equation 7. VOCl + n ...

  7. Microstructures of the oxides on the activated AB{sub 2} and AB{sub 5} metal hydride alloys surface

    Energy Technology Data Exchange (ETDEWEB)

    Young, K., E-mail: kwo.young@BASF.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Chao, B. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Liu, Y. [Electron Microscopy Facility, 145 Linus Pauling Science Center, 2900 SW Campus Way, Oregon State University, Corvallis, OR 97331 (United States); Nei, J. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States)

    2014-09-01

    Highlights: • Morphologies of surface hydroxide of AB{sub 2}, AB{sub 5}, and A{sub 2}B{sub 7} alloys were compared. • Nd promotes the formation of thick rod instead of fine needles. • Both AB{sub 2} and AB{sub 5} show similar buffer oxide + surface oxide structure. • The surface oxide layers in AB{sub 2} are thicker than those from AB{sub 5}. • AB{sub 2} surface is covered by oxide with less solubility in KOH. - Abstract: The surface oxides of the activated metal hydride alloys used as the negative electrode for nickel–metal hydride battery were studied by both scanning and transmission electron microscope techniques. In transition metal based AB{sub 2} metal hydride alloys, the surface of the powder is covered with oxides as a product of oxidation from the electrolyte and protected by zirconium oxide and vanadium-rich BCC-structured secondary phase. In the rare-earth based AB{sub 5} and A{sub 2}B{sub 7} metal hydride alloys, the surface is decorated with nano-structured needles and larger-scaled rods of hydroxides from the precipitation of rare earth ions after the oxidation by the electrolyte. Further TEM studies show the existence of a buffer oxide layer sandwiched between the inclusion-embedded surface oxide and alloy bulk in both AB{sub 2} and AB{sub 5} alloys. In both cases, the inclusions are found to be metallic nanocrystals mainly composed of Ni and Co as determined by electron energy loss spectroscopy, selective area electron diffraction, transmission electron atomic image, and X-ray energy dispersive spectroscopy. The Co-to-Ni ratio in the inclusion is larger than that in the bulk due to the less corrosive nature of Co. The additions of Co and Al in the AB{sub 2} are found to reduce number of activation cycles needed to generate a surface oxide with proper catalytic capability.

  8. Enhanced photocatalytic activity of hydrogenated and vanadium doped TiO2 nanotube arrays grown by anodization of sputtered Ti layers

    Science.gov (United States)

    Motola, Martin; Satrapinskyy, Leonid; Čaplovicová, Mária; Roch, Tomáš; Gregor, Maroš; Grančič, Branislav; Greguš, Ján; Čaplovič, Ľubomír; Plesch, Gustav

    2018-03-01

    TiO2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve the photocatalytic activity of arrays annealed in air (o-TiNT), doping of o-TiNT with vanadium was performed (o-V/TiNT). These non-doped and doped TiNT arrays were also hydrogenated in H2/Ar atmosphere to r-TiNT and r-V/TiNT samples, respectively. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 μm, respectively. In both oxidized and reduced V-doped samples, vanadium is partly dissolved in the structure of anatase and partly deposited in form of oxide on the nanotube surface. Vanadium-doped and reduced samples exhibited higher rates in the photodegradation of organic dyes (compared to non-modified o-TiNT sample) and this is caused by limitation of electron-hole recombination rates and by shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation, and the corresponding efficiency increased in the order (o-TiNT) < (r-TiNT) < (o-V/TiNT) < (r-V/TiNT). Under visible light, only r-TiNT and r-V/TiNT showed significant photocatalytic activity.

  9. The Content of Vanadium in the Egg of the Ascidian, Halocynthia roretzi and Its Changes during the Development

    OpenAIRE

    堀, 令司; 沼宮内, 隆晴; 道端, 斉; Reiji, Hori; Takaharu, Numakunai; Hitoshi, Michibata; 東北大学理学部付属浅虫臨海実験所; 富山大学理学部生物学教室; Asamushi marine biological station, Tohoku University; Biological Institute, Faculty of Science, University of Kanazawa

    1981-01-01

    The vanadium content of the egg and embryo of the ascidian, Halocynthia roretzi was determined by activation analysis. The content of vanadium in an egg remained unchanged during the cleavage. A remarkable increase in the amount of vanadium in the embryo was observed during metamorphosis. Vanadium content in the larva one year after spawning amounted to about 820,000 times of that of the unfertilized egg. The accumulation of vanadium by the ascidian was discussed in comparison with phosphorus.

  10. Characterization and improved solar light activity of vanadium doped TiO{sub 2}/diatomite hybrid catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bin, E-mail: b.wang6@uq.edu.au [School of Chemical and Environmental Engineering, China University of Mining & Technology, Beijing 100083 (China); School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072 (Australia); Zhang, Guangxin, E-mail: z111@163.com [School of Chemical and Environmental Engineering, China University of Mining & Technology, Beijing 100083 (China); Leng, Xue, E-mail: xue.leng@uq.net.au [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072 (Australia); Sun, Zhiming, E-mail: zhiming.baxia@163.com [School of Chemical and Environmental Engineering, China University of Mining & Technology, Beijing 100083 (China); Zheng, Shuilin, E-mail: shuilinzheng8@gmail.com [School of Chemical and Environmental Engineering, China University of Mining & Technology, Beijing 100083 (China)

    2015-03-21

    Highlights: • V-doped TiO{sub 2}/diatomite composite photocatalyst was synthesized. • The physiochemical property and solar light photoactivity were characterized. • The presence and influence of V ions in TiO{sub 2} matrix was systematically analyzed. • The photocatalysis for Rhodamine B were studied under solar light illumination. - Abstract: V-doped TiO{sub 2}/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol–gel method. The diatomite was responsible for the well dispersion of TiO{sub 2} nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO{sub 2}/diatomite hybrids showed red shift in TiO{sub 2} absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO{sub 2} bandgap due to V{sup 4+} ions substituted to Ti{sup 4+} sites. The 0.5% V-TiO{sub 2}/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO{sub 2}/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V{sup 4+} ions incorporated in TiO{sub 2} lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO{sub 2} to produce superoxide radicals ·O{sub 2}{sup –}, while V{sup 5+} species presented on the surface of TiO{sub 2} particles in the form of V{sub 2}O{sub 5} contributed to e{sup –}–h{sup +} separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability.

  11. Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

    Science.gov (United States)

    Natalio, Filipe; André, Rute; Hartog, Aloysius F.; Stoll, Brigitte; Jochum, Klaus Peter; Wever, Ron; Tremel, Wolfgang

    2012-08-01

    Marine biofouling--the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls--is an expensive problem that is currently without an environmentally compatible solution. Biofouling leads to increased hydrodynamic drag, which, in turn, causes increased fuel consumption and greenhouse gas emissions. Tributyltin-free antifouling coatings and paints based on metal complexes or biocides have been shown to efficiently prevent marine biofouling. However, these materials can damage the environment through metal leaching (for example, of copper and zinc) and bacteria resistance. Here, we show that vanadium pentoxide nanowires act like naturally occurring vanadium haloperoxidases to prevent marine biofouling. In the presence of bromide ions and hydrogen peroxide, the nanowires catalyse the oxidation of bromide ions to hypobromous acid (HOBr). Singlet molecular oxygen (1O2) is formed and this exerts strong antibacterial activity, which prevents marine biofouling without being toxic to marine biota. Vanadium pentoxide nanowires have the potential to be an alternative approach to conventional anti-biofouling agents.

  12. Chemistry, spectroscopy and the role of supported vanadium oxides in heterogeneous catalysis

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Keller, D.E.

    2003-01-01

    Supported vanadium oxide catalysts are active in a wide range of applications. In this review, an overview is given of the current knowledge available about vanadium oxide-based catalysts. The review starts with the importance of vanadium in heterogeneous catalysis, a discussion of the molecular

  13. Highly active, bi-functional and metal-free B4C-nanoparticle-modified graphite felt electrodes for vanadium redox flow batteries

    Science.gov (United States)

    Jiang, H. R.; Shyy, W.; Wu, M. C.; Wei, L.; Zhao, T. S.

    2017-10-01

    The potential of B4C as a metal-free catalyst for vanadium redox reactions is investigated by first-principles calculations. Results show that the central carbon atom of B4C can act as a highly active reaction site for redox reactions, due primarily to the abundant unpaired electrons around it. The catalytic effect is then verified experimentally by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests, both of which demonstrate that B4C nanoparticles can enhance the kinetics for both V2+/V3+ and VO2+/VO2+ redox reactions, indicating a bi-functional effect. The B4C-nanoparticle-modified graphite felt electrodes are finally prepared and tested in vanadium redox flow batteries (VRFBs). It is shown that the batteries with the prepared electrodes exhibit energy efficiencies of 88.9% and 80.0% at the current densities of 80 and 160 mA cm-2, which are 16.6% and 18.8% higher than those with the original graphite felt electrodes. With a further increase in current densities to 240 and 320 mA cm-2, the batteries can still maintain energy efficiencies of 72.0% and 63.8%, respectively. All these results show that the B4C-nanoparticle-modified graphite felt electrode outperforms existing metal-free catalyst modified electrodes, and thus can be promising electrodes for VRFBs.

  14. Graphene‐Nanowall‐Decorated Carbon Felt with Excellent Electrochemical Activity Toward VO2 +/VO2+ Couple for All Vanadium Redox Flow Battery

    Science.gov (United States)

    Li, Wenyue; Zhang, Zhenyu; Bian, Haidong; Ng, Tsz‐Wai

    2015-01-01

    3D graphene‐nanowall‐decorated carbon felts (CF) are synthesized via an in situ microwave plasma enhanced chemical vapor deposition method and used as positive electrode for vanadium redox flow battery (VRFB). The carbon fibers in CF are successfully wrapped by vertically grown graphene nanowalls, which not only increase the electrode specific area, but also expose a high density of sharp graphene edges with good catalytic activities to the vanadium ions. As a result, the VRFB with this novel electrode shows three times higher reaction rate toward VO2 +/VO2+ redox couple and 11% increased energy efficiency over VRFB with an unmodified CF electrode. Moreover, this designed architecture shows excellent stability in the battery operation. After 100 charging–discharging cycles, the electrode not only shows no observable morphology change, it can also be reused in another battery and practical with the same performance. It is believed that this novel structure including the synthesis procedure will provide a new developing direction for the VRFB electrode. PMID:27774399

  15. Graphene-Nanowall-Decorated Carbon Felt with Excellent Electrochemical Activity Toward VO2+/VO2+ Couple for All Vanadium Redox Flow Battery.

    Science.gov (United States)

    Li, Wenyue; Zhang, Zhenyu; Tang, Yongbing; Bian, Haidong; Ng, Tsz-Wai; Zhang, Wenjun; Lee, Chun-Sing

    2016-04-01

    3D graphene-nanowall-decorated carbon felts (CF) are synthesized via an in situ microwave plasma enhanced chemical vapor deposition method and used as positive electrode for vanadium redox flow battery (VRFB). The carbon fibers in CF are successfully wrapped by vertically grown graphene nanowalls, which not only increase the electrode specific area, but also expose a high density of sharp graphene edges with good catalytic activities to the vanadium ions. As a result, the VRFB with this novel electrode shows three times higher reaction rate toward VO2+/VO2+ redox couple and 11% increased energy efficiency over VRFB with an unmodified CF electrode. Moreover, this designed architecture shows excellent stability in the battery operation. After 100 charging-discharging cycles, the electrode not only shows no observable morphology change, it can also be reused in another battery and practical with the same performance. It is believed that this novel structure including the synthesis procedure will provide a new developing direction for the VRFB electrode.

  16. Conceptual chemistry approach towards the support effect in supported vanadium oxides: valence bond calculations on the ionicity of vanadium catalysts

    NARCIS (Netherlands)

    Fievez, T.; De Proft, F.; Geerlings, P.; Weckhuysen, B.M.; Havenith, R.W.A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide

  17. Conceptual chemistry approach towards the support effect in supported vanadium oxides : Valence bond calculations on the ionicity of vanadium catalysts

    NARCIS (Netherlands)

    Fievez, Tim; De Proft, Frank; Geerlings, Paul; Weckhuysen, Bert M.; Havenith, Remco W. A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide

  18. The critical role of phosphate in vanadium phosphate oxide for the catalytic activation and functionalization of n-butane to maleic anhydride.

    Science.gov (United States)

    Cheng, Mu-Jeng; Goddard, William A

    2013-03-27

    We used density functional theory to study the mechanism of n-butane oxidation to maleic anhydride on the vanadium phosphorus oxide (VPO) surface. We found that O(1)═P on the V(V)OPO4 surface is the active center for initiating the VPO chemistry through extraction of H from alkane C-H bonds. This contrasts sharply with previous suggestions that the active center is either the V-O bonds or else a chemisorbed O2 on the (V(IV)O)2P2O7 surface. The ability of O(1)═P to cleave alkane C-H bonds is due to its strong basicity coupled with large reduction potentials of nearby V(V) ions. We examined several pathways for the subsequent functionalization of n-butane to maleic anhydride and found that the overall barrier does not exceed 21.7 kcal/mol.

  19. Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

    Science.gov (United States)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

    2018-01-01

    Fluorides are widely used to improve vanadium extraction from shale in China. Sulfuric acid baking-leaching (SABL) was investigated as a means of recovering vanadium which does not require the use of fluorides and avoids the productions of harmful fluoride-containing wastewater. Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale. On the basis of phase transformations and structural changes after baking the shale, a mechanism of vanadium extraction from shale via SABL was proposed. The mechanism can be described as: (1) sulfuric acid diffusion into particles; (2) the formation of concentrated sulfuric acid media in the particles after water evaporation; (3) hydroxyl groups in the muscovite were removed and transient state [SO4 2-] was generated; and (4) the metals in the muscovite were sulfated by active [SO4 2-] and the vanadium was released. Thermodynamics modeling confirmed this mechanism.

  20. Effects of metal compounds with distinct physicochemical properties on iron homeostasis and antibacterial activity in the lungs: chromium and vanadium.

    Science.gov (United States)

    Cohen, Mitchell D; Sisco, Maureen; Prophete, Colette; Yoshida, Kotaro; Chen, Lung-chi; Zelikoff, Judith T; Smee, Jason; Holder, Alvin A; Stonehuerner, Jacqueline; Crans, Debbie C; Ghio, Andrew J

    2010-02-01

    In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. The authors hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both pentavalent vanadium (VV; as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (CrVI; as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5h/day for 5 days) of each at 100 microg metal/m3. Differences in effects on local bacterial resistance between the two VV, and between each CrVI, agents suggested that solubility might be a determinant of in situ immunotoxicity. For the soluble forms, VV had a greater impact on resistance than CrVI, indicating that redox behavior/properties was likely also a determinant. The soluble VV agent was the strongest immunomodulant. Regarding Fe homeostasis, both VV agents had dramatic effects on airway Fe levels. Both also impacted local immune/airway epithelial cell Fe levels in that there were significant increases in production of select cytokines/chemokines whose genes are subject to regulation by HIF-1 (whose intracellular longevity is related to cell Fe status). Our findings contribute to a better understanding of the role that metal compound properties play in respiratory disease pathogenesis and provide a rationale for differing pulmonary immunotoxicities of commonly encountered ambient metal pollutants.

  1. Surface-Activated Amorphous Alloy Fuel Electrodes for Methanol Fuel Cell

    OpenAIRE

    Asahi, Kawashima; Koji, Hashimoto; The Research Institute for Iron, Steel and Other Metals; The Research Institute for Iron, Steel and Other Metals

    1983-01-01

    Amorphous alloy electrodes for electrochemical oxidation of methanol and its derivatives were obtained by the surface activation treatment consisting of electrodeposition of zinc on as-quenched amorphous alloy substrates, heating at 200-300℃ for 30 min, and subsequently leaching of zinc in an alkaline solution. The surface activation treatment provided a new method for the preparation of a large surface area on the amorphous alloys. The best result for oxidation of methanol, sodium formate an...

  2. Biocompatibility and mechanical properties of diamond-like coatings on cobalt-chromium-molybdenum steel and titanium-aluminum-vanadium biomedical alloys.

    Science.gov (United States)

    Hinüber, C; Kleemann, C; Friederichs, R J; Haubold, L; Scheibe, H J; Schuelke, T; Boehlert, C; Baumann, M J

    2010-11-01

    Diamond-like carbon (DLC) films are favored for wear components because of diamond-like hardness, low friction, low wear, and high corrosion resistance (Schultz et al., Mat-wiss u Werkstofftech 2004;35:924-928; Lappalainen et al., J Biomed Mater Res B Appl Biomater 2003;66B:410-413; Tiainen, Diam Relat Mater 2001;10:153-160). Several studies have demonstrated their inertness, nontoxicity, and the biocompatibility, which has led to interest among manufacturers of surgical implants (Allen et al., J Biomed Mater Res B Appl Biomater 2001;58:319-328; Uzumaki et al., Diam Relat Mater 2006;15:982-988; Hauert, Diam Relat Mater 2003;12:583-589; Grill, Diam Relat Mater 2003;12:166-170). In this study, hydrogen-free amorphous, tetrahedrally bonded DLC films (ta-C) were deposited at low temperatures by physical vapor deposition on medical grade Co28Cr6Mo steel and the titanium alloy Ti6Al4V (Scheibe et al., Surf Coat Tech 1996;85:209-214). The mechanical performance of the ta-C was characterized by measuring its surface roughness, contact angle, adhesion, and wear behavior, whereas the biocompatibility was assessed by osteoblast (OB) attachment and cell viability via Live/Dead assay. There was no statistical difference found in the wettability as measured by contact angle measurements for the ta-C coated and the uncoated samples of either Co28Cr6Mo or Ti6Al4V. Rockwell C indentation and dynamic scratch testing on 2-10 μm thick ta-C films on Co28Cr6Mo substrates showed excellent adhesion with HF1 grade and up to 48 N for the critical load L(C2) during scratch testing. The ta-C coating reduced the wear from 3.5 × 10(-5) mm(3)/Nm for an uncoated control sample (uncoated Co28Cr6Mo against uncoated stainless steel) to 1.1 × 10(-7) mm(3)/Nm (coated Co28Cr6Mo against uncoated stainless steel) in reciprocating pin-on-disk testing. The lowest wear factor of 3.9 × 10(-10) mm(3)/Nm was measured using a ta-C coated steel ball running against a ta-C coated and polished Co28Cr6Mo disk

  3. THE INFLUENCE OF NIOBIUM ON THE ACIDITY AND STRUCTURE OF GAMMA-ALUMINA-SUPPORTED VANADIUM OXIDES

    Directory of Open Access Journals (Sweden)

    Sathler M.N.B.

    1998-01-01

    Full Text Available Gamma-alumina-supported niobium oxide was used as a support for vanadium oxides. The influence of the addition of niobium oxide was studied by looking for changes in the structure and acid-base character of superficial species. Vanadium oxide was deposited using the continuous adsorption method; niobium oxide was impregnated using the incipient wetness method. The catalysts were characterized by XPS, UV-visible and IR spectroscopy. Catalytic tests were performed using propane oxidation reaction at 400oC. For coverage below the monolayer, both vanadium and niobium oxides were observed in slightly condensed superficial species. The presence of vanadium oxide on the support was found to increase the Lewis acidity and create some Bronsted acidity. Higher catalytic activity and selectivity for propene were associated with vanadium oxides. The presence of niobium did not contribute to the modification of the chemical properties of superficial vanadium but did decrease the adsorption of vanadium on the alumina.

  4. Lithium-vanadium advanced blanket development. ITER final report on U.S. contribution: Task T219/T220

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Mattas, R.F. [comps.

    1997-07-01

    The objective of this task is to develop the required data base and demonstrate the performance of a liquid lithium-vanadium advanced blanket design. The task has two main activities related to vanadium structural material and liquid lithium system developments. The vanadium alloy development activity included four subtasks: (1.1) baseline mechanical properties of non irradiated base metal and weld metal joints; (1.2) compatibility with liquid lithium; (1.3) material irradiation tests; and (1.4) development of material manufacturing and joining methods. The lithium blanket technology activity included four subtasks: (2.1) electrical insulation development and testing for liquid metal systems; (2.2) MHD pressure drop and heat transfer study for self-cooled liquid metal systems; (2.3) chemistry of liquid lithium; and (2.4) design, fabrication and testing of ITER relevant size blanket mockups. A summary of the progress and results obtained during the period 1995 and 1996 in each of the subtask areas is presented in this report.

  5. Probing the nanoscale structure of the catalytically active overlayer on Pt alloys with rare earths

    DEFF Research Database (Denmark)

    Pedersen, Anders Filsøe; Ulrikkeholm, Elisabeth Therese; Escribano, Maria Escudero

    2016-01-01

    PtxY and PtxGd exhibit exceptionally high activity for oxygen reduction, both in the polycrystalline form and the nanoparticulate form. In order to understand the origin of the enhanced activity of these alloys, we have investigated thin films of these alloys on bulk Pt(111) crystals, i.e. Y/Pt(111...

  6. Benchmark experiment on vanadium assembly with D-T neutrons. Leakage neutron spectrum measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kokooo; Murata, I.; Nakano, D.; Takahashi, A. [Osaka Univ., Suita (Japan); Maekawa, F.; Ikeda, Y.

    1998-03-01

    The fusion neutronics benchmark experiments have been done for vanadium and vanadium alloy by using the slab assembly and time-of-flight (TOF) method. The leakage neutron spectra were measured from 50 keV to 15 MeV and comparison were done with MCNP-4A calculations which was made by using evaluated nuclear data of JENDL-3.2, JENDL-Fusion File and FENDL/E-1.0. (author)

  7. Vanadium(III)-L-cysteine protects cisplatin-induced nephropathy through activation of Nrf2/HO-1 pathway.

    Science.gov (United States)

    Basu, Abhishek; Singha Roy, Somnath; Bhattacharjee, Arin; Bhuniya, Avishek; Baral, Rathindranath; Biswas, Jaydip; Bhattacharya, Sudin

    2016-01-01

    Cisplatin (CDDP) is one of the first-line anticancer drugs; however, the major limitation of CDDP therapy is development of nephrotoxicity (25-35% cases), whose precise mechanism mainly involves oxidative stress, inflammation and cell death. Therefore, in search of a potential chemoprotectant, an organovanadium complex, viz., vanadium(III)-L-cysteine (VC-III) was evaluated against CDDP-induced nephropathy in mice. CDDP was administered intraperitoneally (5 mg/kg b.w.) and VC-III was given by oral gavage (1 mg/kg b.w.) in concomitant and pre-treatment schedule. The results showed that VC-III administration reduced (p HO-1. Moreover, treatment with VC-III significantly (p < 0.001) enhanced CDDP-mediated cytotoxicity in MCF-7 and NCI-H520 human cancer cell lines. Thus, VC-III can serve as a suitable chemoprotectant and increase the therapeutic window of CDDP in cancer patients.

  8. Measurement of Activity of Indium in Liquid Bi-In-Sn Alloys by EMF Method

    Science.gov (United States)

    Kumar, M. R.; Mohan, S.; Behera, C. K.

    2016-08-01

    The electrochemical technique based on a molten salt electrolyte galvanic cell has been used to measure the activity of indium in liquid Bi-In-Sn alloys in the temperature range of 723 K to 855 K along three ternary sections. The activity of tin in Bi-Sn binary alloys has also been measured by the same technique in the above temperature range. The activity of indium in Bi-In-Sn alloys shows negative deviation from Raoult's law for most of the compositions and slight positive deviations for a few indium-rich compositions. The ternary excess molar free energies have been calculated by Darken's treatment. Isoactivity curves at 813 K in the ternary Bi-In-Sn alloys were derived by combining the activity data of In-Sn and Bi-In alloys. The values of excess molar free energy obtained in this study are compared with those calculated from the Muggianu model at 813 K.

  9. Research activities of biomedical magnesium alloys in China

    Science.gov (United States)

    Zheng, Yufeng; Gu, Xuenan

    2011-04-01

    The potential application of Mg alloys as bioabsorable/biodegradable implants have attracted much recent attention in China. Advances in the design and biocompatibility evaluation of bio-Mg alloys in China are reviewed in this paper. Bio-Mg alloys have been developed by alloying with the trace elements existing in human body, such as Mg-Ca, Mg-Zn and Mg-Si based systems. Additionally, novel structured Mg alloys such as porous, composited, nanocrystalline and bulk metallic glass alloys were tried. To control the biocorrosion rate of bio-Mg implant to match the self-healing/regeneration rate of the surrounding tissue in vivo, surface modification layers were coated with physical and chemical methods.

  10. Charpy impact test results for low activation ferritic alloys irradiated to 30 dpa

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-04-01

    Miniature specimens of six low activation ferritic alloys have been impact field tested following irradiation at 370{degrees}C to 30 dpa. Comparison of the results with those of control specimens and specimens irradiated to 10 dpa indicates that degradation in the impact behavior appears to have saturated by {approx}10 dpa in at least four of these alloys. The 7.5Cr-2W alloy referred to as GA3X appears most promising for further consideration as a candidate structural material in fusion reactor applications, although the 9Cr-1V alloy may also warrant further investigation.

  11. Alloying Au surface with Pd reduces the intrinsic activity in catalyzing CO oxidation

    KAUST Repository

    Qian, Kun

    2016-03-30

    © 2016. Various Au-Pd/SiO2 catalysts with a fixed Au loading but different Au:Pd molar ratios were prepared via deposition-precipitation method followed by H2 reduction. The structures were characterized and the catalytic activities in CO oxidation were evaluated. The formation of Au-Pd alloy particles was identified. The Au-Pd alloy particles exhibit enhanced dispersions on SiO2 than Au particles. Charge transfer from Pd to Au within Au-Pd alloy particles. Isolated Pd atoms dominate the surface of Au-Pd alloy particles with large Au:Pd molar ratios while contiguous Pd atoms dominate the surface of Au-Pd alloy particles with small Au:Pd molar ratios. Few synergetic effect of Au-Pd alloy occurs on catalyzing CO oxidation under employed reaction conditions. Alloying Au with Pd reduces the intrinsic activity in catalyzing CO oxidation, and contiguous Pd atoms on the Au-Pd alloy particles are capable of catalyzing CO oxidation while isolated Pd atoms are not. These results advance the fundamental understandings of Au-Pd alloy surfaces in catalyzing CO oxidation.

  12. Tensile and impact behaviour of BATMAN II steels, Ti-bearing reduced activation martensitic alloys

    Science.gov (United States)

    Filacchioni, G.; Casagrande, E.; De Angelis, U.; De Santis, G.; Ferrara, D.; Pilloni, L.

    Two series of Reduced Activation Ferrous alloys (RAF) have been produced and studied by Casaccia's Laboratories. These martensitic alloys are named BATMAN steels. They are among the few presently developed RAF materials to exploit Ti as a carbide forming and grain size stabilizing element instead of Ta. In this work their mechanical properties are illustrated.

  13. Synthesis, structural characterization and antioxidant activity of some vanadium(IV), Mo(VI)/(IV) and Ru(II) complexes of pyridoxal Schiff base derivatives

    Science.gov (United States)

    Elsayed, Shadia A.; Noufal, Aya M.; El-Hendawy, Ahmed M.

    2017-09-01

    New complexes containing vanadium(IV), Mo(VI)/(IV) and Ru(II) derived from Schiff base of pyridoxal and S-benzyldithiocarbazate (H2pysb) or p-toluidine (Hpytol) have been prepared. The structures of the described compounds were elucidated by elemental analyses, spectroscopic techniques (IR, 1H NMR, UV-Vis and EPR) magnetism, molar conductivity and thermal analysis measurements. Their redox behaviors were also studied by cyclic voltammetry. The ligand H2pysb showed coordination to the metal ions in a dibasic tridenate manner through deprotonated phenolate oxygen, azomethine nitrogen and thiolate sulfur, while Hpytol behaved as monobasic bidentate through phenolate oxygen and azomethine nitrogen. The complexes were tested for their antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and the data obtained revealed that the scavenging activity of the complexes towards DPPH is high for the oxovanadium(IV) complexes with lower IC50 values which are comparable to ascorbic acid as a standard antioxidant. The EC50 concentration ratio together with other antioxidant parameters are also reported.

  14. DFT Studies on the Mechanism of the Vanadium-Catalyzed Deoxydehydration of Diols.

    Science.gov (United States)

    Galindo, Agustín

    2016-03-07

    The mechanism of the vanadium-catalyzed deoxydehydration of glycols to alkenes by phosphanes (Chapman, G.; Nicholas, K. M. Chem. Commun. 2013, 49, 8199-8201) has been investigated with density functional calculations. Two alternative pathways, A and B, have been evaluated, and the three stages generally recognized in DODH processes have been identified: (i) activation of the diol by condensation on the vanadium complex and eventual formation of vanadium-glycolate, (ii) oxygen atom transfer to phosphane with reduction to a vanadium(III) species, and, finally, (iii) alkene extrusion from the vanadium-glycolate with regeneration of the starting catalyst. Pathway B, in which the reduction by the phosphane from vanadium(V) to V(III) species occurred before the diol condensation, is energetically preferred to pathway A, in which the diol activation preceded the oxo-transfer to the phosphane reductant.

  15. Structure, activity and kinetics of supported molybdenum oxide and mixed molybdenum-vanadium oxide catalysts prepared by flame spray pyrolysis for propane OHD

    DEFF Research Database (Denmark)

    Høj, Martin; Kessler, Thomas; Beato, Pablo

    2013-01-01

    . The catalytic experiments showed that the most selective molybdenum oxide catalysts for the ODH reaction were those with high Mo loadings of 7 to 15 wt% Mo, while the most selective mixed molybdenum-vanadium oxide catalyst were at 4 wt% Mo, where separate surface species of molybdenum and vanadium oxide were...... observed by Raman spectroscopy. A simple kinetic model based on the propane ODH reaction, parallel combustion of propane and sequential combustion of propene described the experimental results well and could be used to determine the optimal reaction conditions. © 2013 Elsevier B.V....

  16. Synthesis and Characterization of Ni-B Binary Alloys Incorporating ...

    African Journals Online (AJOL)

    The microstructure of a series of binary Ni-B alloys containing various amounts of vanadium additions were investigated by Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Analysis (EDXA). Due to the vanadium addition in the ...

  17. Vanadium oxide based cpd. useful as a cathode active material - is used in lithium or alkali metal batteries to prolong life cycles

    DEFF Research Database (Denmark)

    1997-01-01

    A mixt. of metallic iron particles and vanadium pentoxide contg. V in its pentavalent state in a liq. is reacted to convert at least some of the pentavalent V to its tetravalent state and form a gel. The liq. phase is then sepd. from the oxide based gel to obtain a solid material(I) comprising Fe...

  18. Nanoporous PtFe alloys as highly active and durable electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Duan, Huimei; Hao, Qin; Xu, Caixia

    2014-12-01

    Nanoporous PtFe alloys with two different bimetallic ratios are fabricated by selectively dealloying PtFeAl ternary alloys, characterized by nanoscaled bicontinuous network skeleton with interconnected hollow channels extending in all three dimensions. The reactive components in PtFeAl ternary alloy were sequentially leached out in a highly controllable manner, generating nanoporous architecture with different bimetallic ratios and the typical ligament size as small as 5 nm. These nanoporous PtFe alloys exhibit much enhanced electrocatalytic activity for oxygen reduction reaction compared with the PtFe/C and Pt/C catalysts. The specific and mass activities for oxygen reduction follow the order of nanoporous Pt75Fe25 > nanoporous Pt55Fe45 > PtFe/C > Pt/C. In the absence of any catalyst support, the structure stability of nanoporous PtFe alloys is greatly enhanced with less loss of the electrochemical surface area and the oxygen reduction activity upon long-term potential scan tests compared with PtFe/C and Pt/C catalysts. The as-made nanoporous PtFe alloys thus hold great application potential as promising cathode electrocatalyst in proton exchange membrane fuel cells with the advantages of easy preparation along with superior oxygen reduction activity and durability.

  19. Effect of Cu content on the antibacterial activity of titanium-copper sintered alloys.

    Science.gov (United States)

    Liu, Jie; Li, Fangbing; Liu, Cong; Wang, Hongying; Ren, Baorui; Yang, Ke; Zhang, Erlin

    2014-02-01

    The phase constitution and the microstructure Ti-x Cu (x=2, 5, 10 and 25 wt.%) sintered alloys were investigated by XRD and SEM and the antibacterial activity was assessed in order to investigate the effect of the Cu content on the antibacterial activity. The results have shown that Ti2Cu was synthesized as a main secondary phase in all Ti-Cu alloys while Cu-rich phase was formed in the alloys with 5 wt.% or more copper. Antibacterial tests have showed that the Cu content influences the antibacterial rate seriously and only the alloys with 5 wt.% or high Cu have a strong and stable antibacterial rate, which indicates that the Cu content in Ti-Cu alloys must be at least 5 wt.% to obtain strong and stable antibacterial property. The Cu content also influenced the Cu ion release behavior. High Cu ion release concentration and high Cu ion release rate were observed for Ti-Cu alloys with high Cu content. It was concluded that the Cu content affects the Cu existence and the Cu ion release behavior, which in turn influences the antibacterial property. It was thought that the Cu-rich phase should play an important role in the strong antibacterial activity. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Bimetallic alloy Pt/Ag nanoparticles with enhanced catalytic activity for formic acid oxidation

    Science.gov (United States)

    Guo, Chunmei; Hu, Jingbo

    2014-05-01

    Here, we report the synthesis of Pt/Ag bimetallic alloy catalyst through combining the ion implantation and electrodeposition method. Ag nanoparticles are employed as the seeds for the growth of Pt nanoparticles. Pt/Ag alloy catalyst demonstrates much higher catalytic activity than pure Pt catalyst, which is about three times more active on the basis of equivalent Pt electrochemically active surface area than that of the pure Pt catalyst. The ion implantation of Ag efficiently enhances the catalytic activity of Pt catalyst for formic acid oxidation.

  1. Preparation and activation of micro-arc oxidation films on a TLM titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S; Yu, Z T [Northwest Institute for Non-Ferrous Metal Research, Xi' an, 710016 (China)], E-mail: yusen_1982@163.com

    2008-12-15

    In order to improve the biocompatibility and surface activity of a TLM alloy, a layer of a porous TiO{sub 2} film was prepared by the micro-arc oxidation method on the surface, and then the NH{sup -}{sub 2} active group was introduced on the film by an activation treatment in an aminated solution. The phase identification and surface characteristics of the micro-arc oxidation films were characterized by XRD, XPS, SEM and EDS. The in vitro blood compatibility of the TLM alloy samples with and without surface modification was evaluated by contact angle tests, hemolysis tests and electrochemical tests. The results indicate that the biocompatibility and surface activity of the TLM alloy could be remarkably improved by surface modification of micro-arc oxidation and activation treatment.

  2. Charpy impact test results of four low activation ferritic alloys irradiated at 370{degrees}C to 15 DPA

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    Miniature CVN specimens of four low activation ferritic alloys have been impact tested following irradiation at 370{degrees}C to 15 dpa. Comparison of the results with those of control specimens indicates that degradation in the impact behavior occurs in each of these four alloys. The 9Cr-2W alloy referred to as GA3X and the similar alloy F82H with 7.8Cr-2W appear most promising for further consideration as candidate structural materials in fusion energy system applications. These two alloys exhibit a small DBTT shift to higher temperatures but show increased absorbed energy on the upper shelf.

  3. Microstructure Control of High-alloyed White Cast Iron

    Directory of Open Access Journals (Sweden)

    Kawalec M.

    2014-03-01

    Full Text Available This paper presents the results of studies of high-alloyed white cast iron modified with lanthanum, titanium, and aluminium-strontium. The samples were taken from four melts of high-vanadium cast iron with constant carbon and vanadium content and near-eutectic microstructure into which the tested inoculants were introduced in an amount of 1 wt% respective of the charge weight. The study included a metallographic examinations, mechanical testing, as well as hardness and impact resistance measurements taken on the obtained alloys. Studies have shown that different additives affect both the microstructure and mechanical properties of high-vanadium cast iron.

  4. Prediction of heating rate controlled viscous flow activation energy during spark plasma sintering of amorphous alloy powders

    Science.gov (United States)

    Paul, Tanaji; Harimkar, Sandip P.

    2017-07-01

    The viscous flow behavior of Fe-based amorphous alloy powder during isochronal spark plasma sintering was analyzed under the integrated theoretical background of the Arrhenius and directional structural relaxation models. A relationship between viscous flow activation energy and heating rate was derived. An extension of the pertinent analysis to Ti-based amorphous alloys confirmed the broad applicability of such a relationship for predicting the activation energy for sintering below the glass transition temperature (T g) of the amorphous alloy powders.

  5. Vanadium As a Potential Membrane Material for Carbon Capture: Effects of Minor Flue Gas Species.

    Science.gov (United States)

    Yuan, Mengyao; Liguori, Simona; Lee, Kyoungjin; Van Campen, Douglas G; Toney, Michael F; Wilcox, Jennifer

    2017-10-03

    Vanadium and its surface oxides were studied as a potential nitrogen-selective membrane material for indirect carbon capture from coal or natural gas power plants. The effects of minor flue gas components (SO 2 , NO, NO 2 , H 2 O, and O 2 ) on vanadium at 500-600 °C were investigated by thermochemical exposure in combination with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and in situ X-ray diffraction (XRD). The results showed that SO 2 , NO, and NO 2 are unlikely to have adsorbed on the surface vanadium oxides at 600 °C after exposure for up to 10 h, although NO and NO 2 may have exhibited oxidizing effects (e.g., exposure to 250 ppmv NO/N 2 resulted in an 2.4 times increase in surface V 2 O 5 compared to exposure to just N 2 ). We hypothesize that decomposition of surface vanadium oxides and diffusion of surface oxygen into the metal bulk are both important mechanisms affecting the composition and morphology of the vanadium membrane. The results and hypothesis suggest that the carbon capture performance of the vanadium membrane can potentially be strengthened by material and process improvements such as alloying, operating temperature reduction, and flue gas treatment.

  6. Neurotoxic profiles of vanadium when administered at the onset of ...

    African Journals Online (AJOL)

    Further “immune” assays revealed astrocytic activation (GFAP stain), demyelination (CNPase) and activated microglia (Iba1) due to vanadium which were ameliorated by the administration of vit E to the dams. The pups whose dams were administered with vit E alone showed signs of cellular degeneration which might be ...

  7. The effect of composition on volatility from a copper alloy

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, K.A.; Smolik, G.R.; Wallace, R.S. [Idaho National Engineering Lab., Idaho Falls, Idaho (United States)] [and others

    1994-12-31

    During a Loss of Coolant Accident (LOCA) activated structural material can be mobilized through oxidation. Information on how much material is mobilized in an accident is necessary for performing safety assessments of fusion reactor designs. The Fusion Safety Program at the Idaho National Engineering Laboratory has an experimental program to measure mobilized mass as a function of temperature for various oxidizing environments. Materials studied have included beryllium (important because of its toxicity), copper alloys, a niobium alloy, PCA and HT-9 steel, tungsten (pure and an alloy), and a vanadium alloy. Some materials undergo a significant change in composition during irradiation. An example of this is copper (a candidate for the ITER first wall, divertor substrate, and various instrumentation probes and antennas), which can have as much as 1 wt% zinc due to transmutation. Additionally, as the design for ITER evolves, a slightly different copper alloy may be selected. Compositional changes may affect the extent that various elements are volatilized due to such mechanisms as diffusion through the alloy, and penetration and release from oxide layers formed on the material. To accurately calculate offsite doses for various irradiation scenarios, one must understand the effect of composition on volatility.

  8. Theoretical study of vanadium oxides interaction with Y-zeolite.

    Science.gov (United States)

    Arroyo, M; Sansores, L E; Salcedo, R; Montoya, J A

    2008-12-01

    A current problem about oils and feedstock in fluid catalytic cracking (FCC) is the continuous cumulative deposition of metal contaminants on the catalyst, resulting in important modifications of its properties. Vanadium plays a detrimental role on the catalyst components because enhances the destruction of the Y-zeolite structure during regeneration stage when it is exposed by steam and oxygen at high temperatures. Knowledge of the mechanism interaction of vanadium with the catalyst is important to improve FCC performance. Quantum Molecular Dynamics calculations were done introducing the VO, V2O3, VO2 or V2O5 molecules at the center of a Y-zeolite ring simulating regeneration conditions. The results indicate that the principal reaction is carried out among the zeolite and the vanadium atoms of molecules. This happens, when interaction is presented, since the loss of a hydrogen atom of the active place causes high degree of oxygen reactivity.

  9. Influence of the austenite-martensite transformation in the dimensional stability of a new tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.); Influencia de la transformacion austenita-martensita en la estabilidad dimensional de un nuevo acero para herramientas aleado con niobio (0,08%) y vanadio (0,12%)

    Energy Technology Data Exchange (ETDEWEB)

    Conejero Ortega, G.; Candela Vazquez, N.; Pichel Martinez, M.; Barea del Cerro, R.; Carsi Cebrian, M.

    2014-07-01

    Austenite-martensite transformation influence on the dimensional stability of a new experimental tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.) has been studied. The dimensional stability of this new steel was compared with the dimensional stability of commercial steel, after and before two thermal treatments, T1 (860 degree centigrade) and T2 (900 degree centigrade). The thermal treatments consisted on heating and cooling, at 1 atmosphere of pressure, in N{sub 2} atmosphere furnace, following by heating in a conventional furnace at 180 degree centigrade during 1 hour. Initially, the experimental steel composition and Ac{sub 1} and Ac{sub 3} transformation temperatures were determined by glow-discharge luminescence (GDL) and dilatometric tests, respectively, in order to select the austenization temperatures of T1 and T2 treatments. After hardness measurement, the microstructure of both steels was characterized by X-Ray Diffraction (XRD) and optical metallography, before and after of T1 and T2 thermal treatments. Finally, longitudinal and angular dimensional stability analyses were realized for both commercial and experimental steels. After a contrastive hypothesis analysis, the results showed that the longitudinal relative variation of the experimental steel calculated was around 0.2% and the angular relative variation was not significant. (Author)

  10. Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

    Science.gov (United States)

    Etim, U J; Xu, B; Ullah, Rooh; Yan, Z

    2016-02-01

    Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Vanadium Doped Tungsten Oxide Material - Electrical Physical and Sensing Properties

    Directory of Open Access Journals (Sweden)

    Shishkin N. Y.

    2008-05-01

    Full Text Available The electrical physical and sensing (to VOCs and inorganic gases properties of vanadium doped tungsten oxide in the regions of phase transition temperature were investigated. Vanadium oxide (II dimerization was observed in the doped material, corresponding to new phase transition. The extreme sensitivity and selectivity to chemically active gases and vapors in small concentrations: CO, NOx, NH3 acetone, ethanol near phase transitions temperature was found. Sensor elements were manufactured for the quantitative detection (close to 1 ppm of alcohol and ammonia.

  12. Core-Shell Vanadium Modified Titania@β-In2S3 Hybrid Nanorod Arrays for Superior Interface Stability and Photochemical Activity.

    Science.gov (United States)

    Mumtaz, Asad; Mohamed, Norani Muti; Mazhar, Muhammad; Ehsan, Muhammad Ali; Mohamed Saheed, Mohamed Shuaib

    2016-04-13

    Core-shell rutile TiO2@β-In2S3 and modified V-TiO2@β-In2S3 were synthesized to develop bilayer systems to uphold charge transport via an effective and stable interface. Morphological studies revealed that β-In2S3 was deposited homogeneously on V-TiO2 as compared to unmodified TiO2 nanorod arrays. X-ray photoelectron spectroscopy (XPS) and electron energy loss spectrometry studies verified the presence of various oxidation states of vanadium in rutile TiO2 and the vanadium surface was utilized for broadening the charge collection centers in host substrate layer and hole quencher window. Subsequently, X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectra confirmed the rutile phases of TiO2 and modified V-TiO2 along with the phases of crystalline β-In2S3. XPS valence band study explored the interaction of valence band quazi Fermi levels of β-In2S3 with the conduction band quazi Fermi levels of modified V-TiO2 for enhanced charge collection at the interface. Photoelectrochemical studies show that the photocurrent density of V-TiO2@β-In2S3 is 1.42 mA/cm(2) (1.5AM illumination). Also, the frequency window for TiO2 was broadened by the vanadium modification in rutile TiO2 nanorod arrays, and the lifetime of the charge carrier and stability of the interface in V-TiO2@β-In2S3 were enhanced compared to the unmodified TiO2@β-In2S3. These findings highlight the significance of modifications in host substrates and interfaces, which have profound implications on interphase stability, photocatalysis and solar-fuel-based devices.

  13. Solid-state transformation of single precursor vanadium complex nanostructures to V₂O₅ and VO₂: catalytic activity of V₂O₅ for oxidative coupling of 2-naphthol.

    Science.gov (United States)

    Pradhan, Mukul; Roy, Anindita; Sinha, Arun Kumar; Sahoo, Ramkrishna; Deb, Dibakar; Pal, Tarasankar

    2015-01-28

    A vanadium complex, [(C5H5N)2V2O3·H2O], of different morphologies has been obtained via a modified hydrothermal procedure using pyridine and VOSO4 salt as the starting material. The evolved [(C5H5N)2V2O3·H2O] nanobelts are of 50-200 nm in width and of a length up to several millimeters. At higher temperatures (600 °C), the solid [(C5H5N)2V2O3·H2O] nanostructures are converted to vanadium pentoxide (V2O5) and vanadium dioxide (VO2) when heated in air and nitrogen atmosphere, respectively. During growth, the mechanism of the evolution of octahedra, truncated octahedra, and hollow truncated octahedra of [(C5H5N)2V2O3·H2O] are reported for the first time. These types of well-structured morphology are also isolated while V2O5 and VO2 are evolved. The as-grown belt-like and octahedral morphologies of [(C5H5N)2V2O3·H2O] are retained during the solid-state transformation, suggesting a route to evolve crystalline nanomaterials. Again, the morphological evolution of the [(C5H5N)2V2O3·H2O] nanostructures has been examined to be pyridine and precursor vanadyl sulfate (VS) concentration dependent. Thus, we are able to isolate truncated octahedra as an intermediate during the formation of [(C5H5N)2V2O3·H2O] nanobelts and nanoflowers with a high pyridine (Py) concentration. Interestingly, longer reaction times successively featured the transformation of truncated octahedra into nanobelts. Nanobelt evolution is not observed at low pyridine concentrations. However, the formation of octahedral morphology takes place at low pyridine concentration. All of the nanostructures were critically examined and characterized thoroughly by various physical techniques to ascertain their purity, structure and composition. An interesting, thermodynamically stable, single crystalline product from DMF soluble [(C5H5N)2V2O3·H2O] has been characterized, which indirectly supports the composition of [(C5H5N)2V2O3·H2O]. Selectively, vanadium pentoxide nanobelts have been found to be an

  14. Comparison of bipyridyl, maltol and kojic acid action as organic vanadium ligands on activity of galactosyltransferase (EC 2.4.1.38, some physiological parameters and ultrastructure of Golgi complexes in rat hepatocytes.

    Directory of Open Access Journals (Sweden)

    Wojciech Dabros

    2007-10-01

    Full Text Available The biochemical activity and morphology of control and streptozotocin-diabetic rat liver Golgi complexes were previously investigated by us under influence of some vanadium [V(IV] compounds. The effectiveness of these derivatives depends on the kind of complexing ligands. This paper presents the investigation of the effect of bipyridyl, the ligand of a new vanadium compound, tested by us with maltol and kojic acid (two ligands studied by the present and other authors. The three ligands alone action was tested under the same experimental conditions as in the case of whole compounds with vanadium and applied to liver Golgi complexes of control rats. A preliminary study for maltol and kojic acid had been previously carried out by us parallel with tests of whole vanadium complexes, but valuable differences in biological action found in our condition of experiments suggested the extension of studies to include the two above-mentioned ligands and to compare the effects of the three investigated ligands. The supplementary part of the experiment focused mainly on the ultrastructure of Golgi complexes in hepatocytes. Four groups of animals were used: C - control rats, C + M (maltol, C + (ka2 (kojic acid and C + (bpy2 (bipyridyl. The control rats received 0.09M NaCl as drinking liquid; all the other animals were given 3.6 mmol/L of appropriate ligand solution in 0.09M NaCl during 7 days. All the animals survived the experiments. Only in group C + (bpy2 did the authors observe statistically significant differences as compared with the controls (group C. The differences were detected in physiological studies and manifested as body weight decreased by approximately 20% during the experiment, lower liquid (p<0.001 and food (p<0.01 intake and increase of free blood sugar level (p<0.01. The yield of Golgi membrane isolation decreased in this group (p<0.01. The main investigated biochemical parameter, i.e. the activity of liver Golgi marker enzyme

  15. FIA versatile system for spectrophotometric determinations of vanadium and molybdenum exploring the catalytic activities of V(V) and Mo(VI); Sistema FIA polivalente para determinacoes espectrofotometricas de vanadio e molibdenio explorando as atividades cataliticas de V(V) e Mo(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Gilmara Caseri de

    1996-02-01

    A versatile system for chemical analysis by flow injection analysis was developed and applied for catalytic spectrophotometric determination of vanadium or molybdenum in metallic alloys. The selected methods were based upon indicator reactions chromotropic (CS)-bromate acid or hydrogen iodide-peroxide, respectively. Initially, a model system was proposed, in which common parameters for methods were studied. This included a re-sampling process in which high degrees of samples dilution were obtained. Other parameters such as concentrations and reagents addition order, reaction medium Ph, temperature and ionic power, as well as procedures for sample solubilization, were studied relating to each method. A mini-column with cationic exchanger resin (Dowex 50W-X8, 50-100 mesh, H{sup +} form) was used. The system for vanadium determination processes 120 samples by hour, consuming 2,0 mg CS and 10 mg K Br O{sub 3b}y determination. Concerning the method for molybdenum, the reagents consumption was 2,0 mg KI and 1,0 {mu}L of solution 30% H{sub 2}O{sub 2} by determination, since the analytic velocity was the same, in relation to vanadium.

  16. The Development of a Ti-6Al-4V Alloy via Oxygen Solid Solution Strengthening for Aerospace and Defense Applications

    Science.gov (United States)

    2013-03-01

    aerospace, marine , chemical industries, medical, and military applications (1, 2) because these alloys have high specific strength, high Young’s...conventional titanium alloys used in structural components contain many alloying elements of transition metals such as vanadium (V), niobium (Nb), chromium...process (5) was 23.7 μm and 99.5%, respectively. The content of TiO2 particles was 0 to ~1.5 mass% of the mixture. Next, the aluminum and vanadium

  17. The role of vanadium in the chemical defense of the solitary tunicate, Phallusia nigra.

    Science.gov (United States)

    Odate, Shobu; Pawlik, Joseph R

    2007-03-01

    Ascidians (sea squirts) may defend themselves from predators, biofouling competitors, and bacterial infection by producing secondary metabolites or sequestering acid, but many species also accumulate heavy metals, most notably vanadium. The defensive functions of heavy metals in ascidians remain unclear, and to this end, the solitary Caribbean tunicate, Phallusia nigra, was studied to localize vanadium in its tissues and to assess the defensive properties of vanadium-containing compounds. As determined by flame atomic absorption spectroscopy, the internal tissues and blood contained the highest vanadium concentrations (mean values of 2280 and 1886 ppm dry mass, respectively), followed by the tunic surface (871 ppm dry mass). Results of laboratory feeding assays with the bluehead wrasse, Thalassoma bifasciatum, confirmed outcomes of past studies that demonstrated that vanadyl sulfate (VOSO4.6H20) and sodium vanadate (Na3VO4) were unpalatable to fish, although these salts do not accurately reflect the chelation environment or oxidation state of vanadium in living tunicates. Fresh preparations of whole tunic, internal tissues, and blood were unpalatable to fish, but freezing and thawing of internal tissues and blood rendered them palatable. Crude organic extracts of whole tunic and internal tissues contained vanadium metabolites (225 and 750 ppm dry mass, respectively) and were palatable to T. bifasciatum; crude extracts also exhibited no antimicrobial effects against a panel of four marine bacteria known to be pathogens of marine invertebrates (Vibrio parahaemolyticus, Vibrio harveyi, Leucothrix mucor, and Deleya marina). Nonacidic vanadium (+3) complexes neither deterred predation nor inhibited microbial growth, whereas acidic aqua vanadium (+3 and +4) complexes were unpalatable to 7 bifasciatum and exhibited antimicrobial activity. Difficulties in decoupling low pH from oxidation state and chelation environment of vanadium prevent definitive conclusions about the

  18. Role of laser radiation in activating anodic dissolution under electrochemical machining of metals and alloys

    Directory of Open Access Journals (Sweden)

    Rakhimyanov Kharis

    2017-01-01

    Full Text Available The specific features of electrochemical dissolution of the 12X18H9T stainless steel, the OT-4 titanium alloy and the BK8 hard alloy in the sodium nitrate water solution exposed to 1.06 micrometer wavelength laser radiation were considered. It is found that depassivation of the anode surface is the main mechanism of laser activation in electrochemical dissolving of materials. It is established that the maximum efficiency of laser electrochemical machining is achieved at a pulse repetition frequency of 10 kHz laser radiation. It is connected with the photoactivation mechanism of electrolyte solution molecules, which increases their reaction capacity.

  19. Fabrication of biodegradable Zn-Al-Mg alloy: Mechanical properties, corrosion behavior, cytotoxicity and antibacterial activities.

    Science.gov (United States)

    Bakhsheshi-Rad, H R; Hamzah, E; Low, H T; Kasiri-Asgarani, M; Farahany, S; Akbari, E; Cho, M H

    2017-04-01

    In this work, binary Zn-0.5Al and ternary Zn-0.5Al-xMg alloys with various Mg contents were investigated as biodegradable materials for implant applications. Compared with Zn-0.5Al (single phase), Zn-0.5Al-xMg alloys consisted of the α-Zn and Mg 2 (Zn, Al) 11 with a fine lamellar structure. The results also revealed that ternary Zn-Al-Mg alloys presented higher micro-hardness value, tensile strength and corrosion resistance compared to the binary Zn-Al alloy. In addition, the tensile strength and corrosion resistance increased with increasing the Mg content in ternary alloys. The immersion tests also indicated that the corrosion rates in the following order Zn-0.5Al-0.5Mgcorrosion rate, good biocompatibility and antibacterial activities was believed to be a good candidate as a biodegradable implant material. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Catalytic oxidations by vanadium complexes

    NARCIS (Netherlands)

    Ligtenbarg, A.G J; Hage, R.; Feringa, B.L.

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the

  1. Vanadium Compounds as PTP Inhibitors

    Directory of Open Access Journals (Sweden)

    Elsa Irving

    2017-12-01

    Full Text Available Phosphotyrosine signaling is regulated by the opposing actions of protein tyrosine kinases (PTKs and protein tyrosine phosphatases (PTPs. Here we discuss the potential of vanadium derivatives as PTP enzyme inhibitors and metallotherapeutics. We describe how vanadate in the V oxidized state is thought to inhibit PTPs, thus acting as a pan-inhibitor of this enzyme superfamily. We discuss recent developments in the biological and biochemical actions of more complex vanadium derivatives, including decavanadate and in particular the growing number of oxidovanadium compounds with organic ligands. Pre-clinical studies involving these compounds are discussed in the anti-diabetic and anti-cancer contexts. Although in many cases PTP inhibition has been implicated, it is also clear that many such compounds have further biochemical effects in cells. There also remain concerns surrounding off-target toxicities and long-term use of vanadium compounds in vivo in humans, hindering their progress through clinical trials. Despite these current misgivings, interest in these chemicals continues and many believe they could still have therapeutic potential. If so, we argue that this field would benefit from greater focus on improving the delivery and tissue targeting of vanadium compounds in order to minimize off-target toxicities. This may then harness their full therapeutic potential.

  2. Characterization of vanadium flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2010-10-15

    This report summarizes the work done at Risoe DTU testing a vanadium flow battery as part of the project 'Characterisation of Vanadium Batteries' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  3. Global biogeochemical cycle of vanadium.

    Science.gov (United States)

    Schlesinger, William H; Klein, Emily M; Vengosh, Avner

    2017-12-26

    Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 109 g V/y) and extraction and combustion of fossil fuels (600 × 109 g V/y), humans are the predominant force in the geochemical cycle of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 109 g V/y to 50 × 109 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.

  4. The anti-bacterial activity of titanium-copper sintered alloy against Porphyromonas gingivalis in vitro.

    Science.gov (United States)

    Bai, Bing; Zhang, Erlin; Liu, Junchao; Zhu, Jingtao

    2016-01-01

    This study investigates the anti-bacterial property of Ti-Cu sintered alloys against Porphyromonas gingivalis. The anti-anaerobic property of Ti-Cu sintered alloys against P. gingivalis was investigated by antibacterial activity test, DNA measurement, DAPI staining and morphology observation. The antibacterial rates of the Ti-5Cu against P. gingivalis after 18 and 24 h incubation were 36.04 and 54.39%, and those of Ti-10Cu were 68.69 and 75.39%, which were lower than their anti-aerobic abilities. The concentration of P. gingivalis DNA gradually decreased with the increasing Cu content, which was nearly 50% after 24 h incubation on Ti-10Cu. SEM results showed that the shape of P. gingivalis changed and the bacteria broke apart with the addition of Cu and the extension of the culture time. Ti-Cu sintered alloys could not only kill anaerobic bacteria but also reduce the activity of the survived bacteria. The anti-anaerobic mechanism was thought to be in associated with the Cu ion released from Ti-Cu alloy.

  5. Medium carbon vanadium steels for closed die forging; Acos de medio carbono microligados ao vanadio para forjaria em matriz fechada

    Energy Technology Data Exchange (ETDEWEB)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1993-12-31

    This work analyses the medium carbon micro alloyed vanadium potential for closed die forged production. The steels reach the mechanical resistance requests during cooling after forging, eliminating the subsequent thermal treatment. Those steels also present good fatigue resistance and machinability. The industrial scale experiments are also reported 16 refs., 21 figs.

  6. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    Science.gov (United States)

    Mueller, Michael; Baik, Seungyun; Jeon, Hojeong; Kim, Yuchan; Kim, Jungtae; Kim, Young Jun

    2015-05-01

    The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V2O5 precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V2O5 precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V2O5 precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/VxOx composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V2O5 composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of a mineralizing aid, such as the two cysteine-constrained peptides on the phage surface, and has potential for use in nanotechnology applications.

  7. Antimicrobial activity of different copper alloy surfaces against copper resistant and sensitive Salmonella enterica.

    Science.gov (United States)

    Zhu, Libin; Elguindi, Jutta; Rensing, Christopher; Ravishankar, Sadhana

    2012-05-01

    Copper has shown antibacterial effects against foodborne pathogens. The objective of this study was to evaluate the antibacterial activity of copper surfaces on copper resistant and sensitive strains of Salmonella enterica. Six different copper alloy coupons (60-99.9% copper) were tested along with stainless steel as the control. The coupons were surface inoculated with either S. Enteritidis or one of the 3 copper resistant strains, S. Typhimurium S9, S19 and S20; stored under various incubation conditions at room temperature; and sampled at various times up to 2 h. The results showed that under dry incubation conditions, Salmonella only survived 10-15 min on high copper content alloys. Salmonella on low copper content alloys showed 3-4 log reductions. Under moist incubation conditions, no survivors were detected after 30 min-2 h on high copper content alloys, while the cell counts decreased 2-4 logs on low copper content coupons. Although the copper resistant strains survived better than S. Enteritidis, they were either completely inactivated or survival was decreased. Copper coupons showed better antimicrobial efficacy in the absence of organic compounds. These results clearly show the antibacterial effects of copper and its potential as an alternative to stainless steel for selected food contact surfaces. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Vanadium, rubidium and potassium in Octopus vulgaris (Mollusca: Cephalopoda

    Directory of Open Access Journals (Sweden)

    Sónia Seixas

    2005-06-01

    Full Text Available The levels of vanadium, rubidium and potassium were determined in Octopus vulgaris caught during commercial fishing activities at three locations (Cascais, Santa Luzia and Viana do Castelo in Portugal in autumn and spring. We determined the concentration of these elements in digestive gland, branchial heart, gills, mantle and arms in males and females. At least five males and five females were assessed for each season/location combination. Elemental concentrations were determined by Particle Induced X-ray Emission (PIXE. Vanadium was detectable only in digestive gland and branchial heart samples. Its concentration was not correlated with total weight, total length or mantle length. There were no differences in concentrations of V, Rb and K between sexes. There were significant differences in vanadium concentrations in branchial hearts in autumn between samples from Viana do Castelo and those from the other two sites. We found a significant positive relationship between the concentration of vanadium and those of potassium and rubidium in branchial hearts. Branchial hearts appear to play an important role in decontamination of V.

  9. Sulfur-vanadium oxide gel composites as thin film cathodes for rechargeable lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S.P.; Gavrilov, A.B.; Skotheim, T.A.

    1998-07-01

    A class of novel electroactive cathode materials based on composites produced from elemental sulfur and vanadium oxide xerogels or aerogels has been developed as models for lithium battery applications. The use of elemental sulfur in rechargeable lithium batteries has been hindered due to certain limitations such as, very low electronic conductivity and the out-diffusion of polysulfides during the cycling process which reduces the cycling efficiency. Vanadium oxide xerogels and aerogels have certain desirable characteristic physico-chemical properties, such as, high surface areas with nono-scale interconnecting porosity, high electronic conductivity, non- or nanocrystallinity, and oxidation reduction catalytic activity. Since these properties may improve the performance of sulfur based rechargeable batteries, a family of composite cathodes containing elemental sulfur and vanadium oxide gels were produced. The performance of the composites cathodes, in thin film form, were evaluated in coin cells and AA cells with metallic lithium anodes and liquid electrolytes. The multifunctional role of vanadium oxide gels on the cell performance of the cells having composite cathodes has been qualitatively explored. Results indicate that the cathodes having xerogel composites based on vanadium oxide sol from vanadium oxide isopropoxide can be made with high sulfur content (80 wt %) and with low carbon content (5 wt %) and without any polymer binder. This shows the contribution of adhesive properties and electronic conductivity of vanadium oxide xerogels. A significant suppression of polysulfide out-diffusion is observed with appropriate processing of the composite cathodes. It is anticipated that the nanoscale interconnecting porosity of gels plays an important role in this behavior. An excellent rate capability is observed with the vanadium-oxide sulfur composite cathodes indicating the contribution of intrinsic electrochemical properties of the vanadium oxide.

  10. Research and Development on Titanium Alloys

    Science.gov (United States)

    1949-10-31

    are being prepared by the Norton Company for evaluation. Titanium boride , tantalum boride , zirconium boride , tungsten boride , and molybdenum boride ...alloying additionO will be ex- tended. 9 Ternary alloys of manganese and carbon, manganese and vanadium, and molybdenum and tungsten, prepared by...graphite crucibles lined with tantalum carbide and turgsten boride as refractories for molten titanium,. Melts were prepared In crucibles made of zirconium

  11. Activation Energies for Diffusion in Pure Metals and Concentrated Binary Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Toth, L. E.; Searcy, A. W.

    1963-07-16

    A modification of Le Claire's microscopic model for self-diffusion is developed in a form suitable for prediction of activation energies for diffusion in disordered substitutional solutions as well as in pure metals. Bonding is considered as a localized interaction, and the energy of bonding between atoms of different types is taken as the arithmetic mean of the energies in the pure elements. The activation energies for vacancy formation and migration in substitutional alloys are shown to depend on the empirical constants developed for self-diffusion when the equations are adjusted for the mole fractions of the two elements. The calculated results for alloy diffusion usually agree with the experimental values to within the experimental errors.

  12. Method of making active magnetic refrigerant, colossal magnetostriction and giant magnetoresistive materials based on Gd-Si-Ge alloys

    Science.gov (United States)

    Gschneidner, Jr., Karl A.; Pecharsky, Alexandra O.; Pecharsky, Vitalij K.

    2003-07-08

    Method of making an active magnetic refrigerant represented by Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4 alloy for 0.ltoreq.x.ltoreq.1.0 comprising placing amounts of the commercially pure Gd, Si, and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to homogenize a microstructure of the solidified material, and then cooling sufficiently fast to prevent the eutectoid decomposition and improve magnetocaloric and/or the magnetostrictive and/or the magnetoresistive properties thereof.

  13. Characterization of Vanadium Flow Battery

    DEFF Research Database (Denmark)

    Bindner, Henrik W.; Krog Ekman, Claus; Gehrke, Oliver

    This report summarizes the work done at Risø-DTU testing a vanadium flow battery as part of the project “Characterisation of Vanadium Batteries” (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery...... has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risø DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration...... of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses...

  14. Brain Metal Distribution and Neuro-Inflammatory Profiles after Chronic Vanadium Administration and Withdrawal in Mice

    Directory of Open Access Journals (Sweden)

    Oluwabusayo R. Folarin

    2017-07-01

    cortex, cellular degeneration (loss of dendritic arborization and cell death in the Hippocampal CA1 pyramidal cells and Purkinje cells of the cerebellum, including astrocytic and microglial activation in vanadium exposed brains which were all attenuated in the withdrawal group. With exposure into old age, the evident neuropathology was microgliosis, while progressive astrogliosis became more attenuated. We have shown that chronic administration of vanadium over a lifetime in mice resulted in metal accumulation which showed regional variabilities with time. The metal profile and pathological effects were not completely eliminated from the brain even after a long time withdrawal from vanadium metal.

  15. High swelling rates observed in neutron-irradiated V-Cr and V-Si binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Garner, F.A.; Gelles, D.S. [Pacific Northwest Lab., Richland, WA (United States); Takahashi, H.; Ohnuki, S.; Kinoshita, H. [Hokkaido Univ., Sapporo (Japan); Loomis, B.A. [Argonne National Lab., IL (United States)

    1991-11-01

    Additions of 5 to 14 wt% chromium to vanadium lead to very large swelling rates during neutron irradiation of the binary alloys, with swelling increasing strongly at higher irradiation temperatures. Addition of 2 wt% silicon to vanadium also leads to very large swelling rates but swelling decreases with increasing irradiation temperature. Addition of 1 wt% zirconium does not yield high swelling rates, however.

  16. Leaching characteristics of vanadium in mine tailings and soils near a vanadium titanomagnetite mining site.

    Science.gov (United States)

    Yang, Jinyan; Tang, Ya; Yang, Kai; Rouff, Ashaki A; Elzinga, Evert J; Huang, Jen-How

    2014-01-15

    A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with vanadium readily mobilised. Column experiments revealed that only vanadium in the soil and mine tailing was leachable. The vanadium concentrations in the soil leachates did not vary considerably, but decreased with the leachate volume in the mine tailing leachates. This suggests that there was a smaller pool of leachable vanadium in the mine tailings compared to that in the soil. Drought and rewetting increased the vanadium concentrations in the soil and mine tailing leachates from 20μgL(-1) to 50-90μgL(-1), indicating the potential for high vanadium release following periods of drought. Experiments with soil columns overlain with 4, 8 and 20% volume mine tailings/volume soil exhibited very similar vanadium leaching behaviour. These results suggest that the transport of vanadium to the subsurface is controlled primarily by the leaching processes occurring in soils. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    Science.gov (United States)

    Alvarado-Gámez, Ana Lorena; Alonso-Lomillo, María Asunción; Domínguez-Renedo, Olga; Arcos-Martínez, María Julia

    2014-01-01

    A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 μM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water. PMID:24569772

  18. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    Directory of Open Access Journals (Sweden)

    Ana Lorena Alvarado-Gámez

    2014-02-01

    Full Text Available A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 µM, a repeatability of 7.7% (n = 4 and a reproducibility of 8% (n = 3. A study of the possible interferences shows that the presence of Mo(VI, Cr(III, Ca(II and W(VI, may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water.

  19. Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg

    and dealloying due to kinetic barriers, despite the thermodynamic driving force for dissolution. This is followed by our results on trying to decouple the strain and ligand effects for platinum skin structures, and determining whether there is any correlation between adsorption energy and surface stability...... in these systems. We find that there is such a correlation for some adsorbates, indicating that there exists a limit for the stability of an overlayer for a given adsorption strength. Finally, we introduce our work on platinum alloy nanoparticles, and our attempt to isolate the features which result......In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts...

  20. Fusion materials: Technical evaluation of the technology of vandium alloys for use as blanket structural materials in fusion power systems

    Energy Technology Data Exchange (ETDEWEB)

    1993-08-04

    The Committee`s evaluation of vanadium alloys as a structural material for fusion reactors was constrained by limited data and time. The design of the International Thermonuclear Experimental Reactor is still in the concept stage, so meaningful design requirements were not available. The data on the effect of environment and irradiation on vanadium alloys were sparse, and interpolation of these data were made to select the V-5Cr-5Ti alloy. With an aggressive, fully funded program it is possible to qualify a vanadium alloy as the principal structural material for the ITER blanket in the available 5 to 8-year window. However, the data base for V-5Cr-5Ti is United and will require an extensive development and test program. Because of the chemical reactivity of vanadium the alloy will be less tolerant of system failures, accidents, and off-normal events than most other candidate blanket structural materials and will require more careful handling during fabrication of hardware. Because of the cost of the material more stringent requirements on processes, and minimal historical worlding experience, it will cost an order of magnitude to qualify a vanadium alloy for ITER blanket structures than other candidate materials. The use of vanadium is difficult and uncertain; therefore, other options should be explored more thoroughly before a final selection of vanadium is confirmed. The Committee views the risk as being too high to rely solely on vanadium alloys. In viewing the state and nature of the design of the ITER blanket as presented to the Committee, h is obvious that there is a need to move toward integrating fabrication, welding, and materials engineers into the ITER design team. If the vanadium allay option is to be pursued, a large program needs to be started immediately. The commitment of funding and other resources needs to be firm and consistent with a realistic program plan.

  1. Hollow raspberry-like PdAg alloy nanospheres: High electrocatalytic activity for ethanol oxidation in alkaline media

    Science.gov (United States)

    Peng, Cheng; Hu, Yongli; Liu, Mingrui; Zheng, Yixiong

    2015-03-01

    Palladium-silver (PdAg) alloy nanospheres with unique structure were prepared using a one-pot procedure based on the galvanic replacement reaction. Their electrocatalytic activity for ethanol oxidation in alkaline media was evaluated. The morphology and crystal structure of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical characterization techniques, including cyclic voltammetry (CV) and chronoamperometry (CA) measurements were used to analyze the electrochemical performance of the PdAg alloy nanospheres. The SEM and TEM images showed that the PdAg alloy nanospheres exhibit a hierarchical nanostructure with hollow interiors and porous walls. Compared to the commercial Pd/C catalyst, the as-prepared PdAg alloy nanospheres exhibit superior electrocatalytic activity and stability towards ethanol electro-oxidation in alkaline media, showing its potential as a new non-Pt electro-catalyst for direct alcohol fuel cells (DAFCs).

  2. Effects of alloying elements and heat treatments on mechanical properties of Korean reduced-activation ferritic-martensitic steel

    Science.gov (United States)

    Chun, Y. B.; Kang, S. H.; Noh, S.; Kim, T. K.; Lee, D. W.; Cho, S.; Jeong, Y. H.

    2014-12-01

    As part of an alloy development program for Korean reduced-activation ferritic-martensitic (RAFM) steel, a total of 37 program alloys were designed and their mechanical properties were evaluated with special attention being paid to the effects of alloying elements and heat treatments. A reduction of the normalizing temperature from 1050 °C to 980 °C was found to have a positive effect on the impact resistance, resulting in a decrease in ductile-brittle transition-temperature (DBTT) of the program alloys by an average of 30 °C. The yield strength and creep rupture time are affected strongly by the tempering time at 760 °C but at the expense of ductility. Regarding the effects of the alloying elements, the addition of trace amounts of Zr enhances both the creep and impact resistance: the lowest DBTT was observed for the alloys containing 0.005 wt.% Zr, whereas the addition of 0.01 wt.% Zr extends the creep rupture-time under an accelerated condition. The enhanced impact resistance owing to the normalizing at lower temperature is attributed to a more refined grain structure, which provides more barriers to the propagation of cleavage cracks. Solution softening by Zr addition is suggested as a possible mechanism for enhanced resistance to both impact and creep of the program alloys.

  3. Current status and associated human health risk of vanadium in soil in China.

    Science.gov (United States)

    Yang, Jie; Teng, Yanguo; Wu, Jin; Chen, Haiyang; Wang, Guoqiang; Song, Liuting; Yue, Weifeng; Zuo, Rui; Zhai, Yuanzheng

    2017-03-01

    A detailed assessment of vanadium contamination characteristics in China was conducted based on the first national soil pollution survey. The map overlay analysis was used to evaluate the contamination level of vanadium and the non-carcinogenic risk assessment model was calculated to quantify the vanadium exposure risks to human health. The results showed that, due to the drastically increased mining and smelting activities, 26.49% of soils were contaminated by vanadium scattered in southwest of China. According to Canadian soil quality guidelines, about 8.6% of the national soil pollution survey samples were polluted, and pose high non-carcinogenic risks to the public, especially to children living in the vicinity of heavily polluted mining areas. We propose the area near the boundary of Yunnan, Guizhou, Guangxi, and Sichuan provinces as priority control areas due to their higher geochemical background or higher health risks posed to the public. Finally, recommendations for management are proposed, including minimization of contaminant inputs, establishing stringent monitoring program, using phytoremediation, and strengthening the enforcement of relevant laws. Therefore, this study provides a comprehensive assessment of soil vanadium contamination in China, and the results will provide valuable information for China's soil vanadium management and risk avoidance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Evaluation of mechanically alloyed Cu-based powders as filler alloy for brazing tungsten to a reduced activation ferritic-martensitic steel

    Science.gov (United States)

    de Prado, J.; Sánchez, M.; Ureña, A.

    2017-07-01

    80Cu-20Ti powders were evaluated for their use as filler alloy for high temperature brazing of tungsten to a reduced activation ferritic/martensitic steel (Eurofer), and its application for the first wall of the DEMO fusion reactor. The use of alloyed powders has not been widely considered for brazing purposes and could improve the operational brazeability of the studied system due to its narrower melting range, determined by DTA analysis, which enhances the spreading capabilities of the filler. Ti contained in the filler composition acts as an activator element, reacting and forming several interfacial layers at the Eurofer-braze, which enhances the wettability properties and chemical interaction at the brazing interface. Brazing thermal cycle also activated the diffusion phenomena, which mainly affected to the Eurofer alloying elements causing in it a softening band of approximately 400 μm of thickness. However, this softening effect did not degrade the shear strength of the brazed joints (94 ± 23 MPa), because failure during testing was always located at the tungsten-braze interface.

  5. Influence of strain rate on the twin and slip activity of a magnesium alloy containing neodymium

    Energy Technology Data Exchange (ETDEWEB)

    Dudamell, N.V. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Hidalgo-Manrique, P., E-mail: paloma.hidalgo@imdea.org [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Chakkedath, A.; Chen, Z.; Boehlert, C.J. [Michigan State University, East Lansing, MI 48824-1226 (United States); Gálvez, F. [ETS Ingenieros de Caminos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Yi, S.; Bohlen, J.; Letzig, D. [Magnesium Innovation Centre, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht (Germany); Pérez-Prado, M.T. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2013-10-20

    The mechanical behavior of an extruded magnesium–manganese alloy containing 1 wt% of neodymium (MN11) has been investigated at temperatures ranging from room temperature to 400 °C at both quasi-static and dynamic rates. Conventional ex-situ tests, carried out in compression along the extrusion axis (EA), have been combined with in-situ tests in a scanning electron microscope (SEM) in order to elucidate the effect of a rare earth (RE) addition on the dominant deformation mechanisms. An unusually large activity of twinning was observed at room temperature in a wide range of quasi-static rates. Furthermore, the twinning activity has been found to increase at temperatures around 250 °C, where clear signs of dynamic strain aging (DSA) are also apparent. The enhanced twinning activity compared to conventional Mg alloys, not containing RE elements, is attributed to an increase in the critical resolved shear stress of basal slip (CRSS{sub basal}) due to the presence of intermetallic RE-containing particles and to the Nd atoms in solid solution. The surprising decrease of the twinning activity at dynamic rates (∼10{sup 3} s{sup −1}) may be explained by a decrease in the CRSS{sub basal} as the intermetallic RE-containg particles and the Nd solid solution strengthening become less effective with increasing strain rate.

  6. Interaction of vanadium and phosphorus in chicks.

    Science.gov (United States)

    Hill, C H

    1994-12-01

    Studies were carried out to determine the effect of dietary vanadium on chicks fed phosphorus deficient and control diets. Vanadium at 50 mg/kg of diet decreased growth of both control and deficient chicks. The high mortality among the phosphorus deficient chicks was significantly alleviated by the presence of vanadium. The increased relative ventricular weights found among the deficient chicks was also alleviated by the presence of dietary vanadium. Vanadium fed at 10 or 20 mg/kg diet did not reduce growth rate but significantly reduced mortality among chicks fed the deficient diet and decreased the relative ventricle weights. Time course studies revealed that chicks are hatched with high relative ventricular weights (.83% of body wt) and remain at that level among chicks fed the phosphorus deficient diet. The addition of vanadium or phosphate to the diet resulted in a progressive decrease in relative ventricular weights. The inclusion of vanadium in the diet resulted in increased serum phosphorus levels among the deficient chicks that may be related to the decrease in mortality and relative ventricle weights.

  7. A simple spectrophotometric determination of trace amounts of vanadium using thionin

    Directory of Open Access Journals (Sweden)

    Tom Cherian

    2005-12-01

    Full Text Available A simple and sensitive spectrophotometric method has been developed for the determination of trace amounts of vanadium using thionin as a chromogenic reagent. The proposed method is based on the reaction of vanadium(V with potassium iodide in acid medium to liberate iodine, which bleaches the violet colour of thionin and is measured at 600 nm. This decrease in absorbance is directly proportional to the vanadium(V concentration and obeys Beer's law in the range of 0.2-10 μgmL-1 of V(V. The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method were found to be 2.298 x 104 Lmol-1cm-1, 0.52 x 10-2 μgcm-2, 0.035 μgmL-1 and 0.11 μgmL-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described. The developed method has been successfully applied to the analysis of the vanadium in synthetic and alloy samples.

  8. Intermetallic Alloys as CO Electroreduction Catalysts-Role of Isolated Active Sites

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    , we studied intermetallic compounds consisting of transition metal (TM) elements that can reduce CO (Ru, Co, Rh, Ir, Ni, Pd, Pt, and Cu) separated by TM and post transition metal elements (Ag, Au, Cd, Zn, Hg, In, Sn, Pb, Sb, and Bi) that are very poor HER catalysts. In total, 34 different stable...... binary bulk alloys forming from these elements have been investigated using density functional theory calculations. The electronic and geometric properties of the catalyst surface can be tuned by varying the size of the active centers and the elements forming them. We have identified six different...

  9. Determination of the activation energy in a cast aluminium alloy by TEM and DSC

    Energy Technology Data Exchange (ETDEWEB)

    Ovono Ovono, D. [Laboratoire Roberval, University of Technology of Compiegne, 60205 Compiegne (France)]. E-mail: delavand.ovono-ovono@utc.fr; Guillot, I. [Centre d' Etudes de Chimie Metallurgie, UPR2801 CNRS, 94407 Vitry-sur-Seine (France); Massinon, D. [Fonderie Montupet, 60181 Nogent-sur-Oise (France)

    2007-04-25

    The precipitation behaviour and microstructure development of the A319 alloy during ageing were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM and STEM). During T5 treatment, {theta}' precipitates with an average size of about 18 nm were observed by TEM. The precipitate sizes increased with ageing temperature and attained an average size of 107 nm. In addition, there was a linear relationship between precipitate growth temperature and the cube of the precipitate size. This indicates that precipitate growth of the A319 alloy belongs to a thermal activated process of the Arrhenius type. The activation energy for the precipitate growth was calculated to be 140.4 {+-} 13.3 kJ/mol. However, under continuous heating conditions, the activation energy for the precipitate growth obtained by Kissinger plot was determined to be 119.5 {+-} 8.3 kJ/mol. Allowing for experimental error, both values are comparable and are related to the diffusion of Cu and/or Si in Al.

  10. Effects of surface contamination and cleaning with hypochlorite wipes on the antibacterial activity of copper-alloyed antibacterial stainless steel.

    Science.gov (United States)

    Kawakami, Hiroshi; Hayashi, Takatsuna; Nishikubo, Hideyuki; Morikawa, Akifumi; Suzuki, Satoshi; Sato, Yoshihiro; Kikuchi, Yasushi

    2014-01-01

    Effects of surface contamination and cleaning with hypochlorite wipes on the antibacterial activity of copper-alloyed stainless steel were studied. The antibacterial activity of copper alloyed stainless steel decreased with the increase in the amount of surface contaminant, and the bacterial counts from specimens contaminated with a contaminant, e.g. 1.6 × 10(-2) μg/mm(2) of bovine serum albumin, were not significantly different from those from ordinary stainless steel specimens. The once contaminated surface could regain its antibacterial activity when it was sufficiently wiped clean with sterile wipes loaded with sodium hypochlorite solution.

  11. Vanadium Bioleaching Behavior by Acidithiobacillus ferrooxidans from a Vanadium-Bearing Shale

    Directory of Open Access Journals (Sweden)

    Dunpei Wei

    2018-01-01

    Full Text Available This study investigated bioleaching behavior of vanadium from a vanadium-bearing shale using Acidithiobacillus ferrooxidans (A. ferrooxidans. Results showed a maximum recovery of 62% vanadium in 1.2-day bioleaching, which was 22.45% higher than the controls. Then, the vanadium leaching efficiency decreased significantly, only 24% of that was obtained on the tenth day. The vanadium extraction in 1.2 days was mainly attributed to the dissolution of vanadium in free oxides of shale. Fe3+ produced by A. ferrooxidans promoted the dissolution process. X-ray diffraction (XRD patterns of the leached residues confirmed the generation of jarosite. SEM-EDS analysis of the residues indicated that jarosite adsorbed on the shale and inhibited the further dissolution of vanadium. The relevance of V, Fe, S, O was quite good in the energy disperse X-ray spectrometry (EDS element mapping of jarosite, and acid-washing of the jarosite resulted in 31.6% of the vanadium in the precipitates desorption, indicating that the decrease of vanadium leaching efficiency in bioleaching process was caused by both adsorption and co-precipitation with jarosite.

  12. Hermetic diamond capsules for biomedical implants enabled by gold active braze alloys.

    Science.gov (United States)

    Lichter, Samantha G; Escudié, Mathilde C; Stacey, Alastair D; Ganesan, Kumaravelu; Fox, Kate; Ahnood, Arman; Apollo, Nicholas V; Kua, Dunstan C; Lee, Aaron Z; McGowan, Ceara; Saunders, Alexia L; Burns, Owen; Nayagam, David A X; Williams, Richard A; Garrett, David J; Meffin, Hamish; Prawer, Steven

    2015-01-01

    As the field of biomedical implants matures the functionality of implants is rapidly increasing. In the field of neural prostheses this is particularly apparent as researchers strive to build devices that interact with highly complex neural systems such as vision, hearing, touch and movement. A retinal implant, for example, is a highly complex device and the surgery, training and rehabilitation requirements involved in deploying such devices are extensive. Ideally, such devices will be implanted only once and will continue to function effectively for the lifetime of the patient. The first and most pivotal factor that determines device longevity is the encapsulation that separates the sensitive electronics of the device from the biological environment. This paper describes the realisation of a free standing device encapsulation made from diamond, the most impervious, long lasting and biochemically inert material known. A process of laser micro-machining and brazing is described detailing the fabrication of hermetic electrical feedthroughs and laser weldable seams using a 96.4% gold active braze alloy, another material renowned for biochemical longevity. Accelerated ageing of the braze alloy, feedthroughs and hermetic capsules yielded no evidence of corrosion and no loss of hermeticity. Samples of the gold braze implanted for 15 weeks, in vivo, caused minimal histopathological reaction and results were comparable to those obtained from medical grade silicone controls. The work described represents a first account of a free standing, fully functional hermetic diamond encapsulation for biomedical implants, enabled by gold active alloy brazing and laser micro-machining. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Analysis of zirconium and nickel based alloys and zirconium oxides by relative and internal monostandard neutron activation analysis methods

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, Amol D.; Acharya, Raghunath; Reddy, Annareddy V. R. [Bhabha Atomic Research Centre, Mumbai (India)

    2017-04-15

    The chemical characterization of metallic alloys and oxides is conventionally carried out by wet chemical analytical methods and/or instrumental methods. Instrumental neutron activation analysis (INAA) is capable of analyzing samples nondestructively. As a part of a chemical quality control exercise, Zircaloys 2 and 4, nimonic alloy, and zirconium oxide samples were analyzed by two INAA methods. The samples of alloys and oxides were also analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and direct current Arc OES methods, respectively, for quality assurance purposes. The samples are important in various fields including nuclear technology. Samples were neutron irradiated using nuclear reactors, and the radioactive assay was carried out using high-resolution gamma-ray spectrometry. Major to trace mass fractions were determined using both relative and internal monostandard (IM) NAA methods as well as OES methods. In the case of alloys, compositional analyses as well as concentrations of some trace elements were determined, whereas in the case of zirconium oxides, six trace elements were determined. For method validation, British Chemical Standard (BCS)-certified reference material 310/1 (a nimonic alloy) was analyzed using both relative INAA and IM-NAA methods. The results showed that IM-NAA and relative INAA methods can be used for nondestructive chemical quality control of alloys and oxide samples.

  14. Effects of Vanadium Ions in Different Oxidation States on Myosin ATPase Extracted from the Solitary Ascidian, Halocynthia roretzi (Drasche) : Biochemistry

    OpenAIRE

    Hitoshi, Michibata; YUTAKA, ZENKO; Kenji, YAMADA; Masato, HASEGAWA; TATSURO, TERADA; TAKAHARU, NUMAKUANI; Biological Institute, Faculty of Science, University of Kanazawa; Department of Chemistry, Toyama College of Technology; Marine Biological Station,Tohoku University

    1989-01-01

    Some ascidians are known to accumulate vanadium ion within their tissues by 10^6-fold as that in sea water and store the metal ion in its reduced tetravalent and/or trivalent states. It is also well known that phosphoenzymes are inhibited by pentavalent vanadium ion over a range of 10nM to 1mM. In the present experiment we have therefore examined the effects of vanadium ions in different oxidation states on the activity of myosin ATPase extracted from the mantle of the ascidian, Halocynthia r...

  15. Mesoporous Vanadium Nitride Synthesized by Chemical Routes

    National Research Council Canada - National Science Library

    Mishra, Pragnya P; Theerthagiri, J; Panda, Rabi N

    2014-01-01

    Nanocrystalline vanadium nitride (VN) materials are synthesized by two different routes, namely, the urea route and the ammonia route, using various V2O5 precursors obtained by citric acid–based sol–gel method...

  16. Dislocation Climb Sources Activated by 1 MeV Electron Irradiation of Copper-Nickel Alloys

    DEFF Research Database (Denmark)

    Barlow, P.; Leffers, Torben

    1977-01-01

    Climb sources emitting dislocation loops are observed in Cu-Ni alloys during irradiation with 1 MeV electrons in a high voltage electron microscope. High source densities are found in alloys containing 5, 10 and 20% Ni, but sources are also observed in alloys containing 1 and 2% Ni. The range of ...

  17. Study of microstructure in vanadium–palladium alloys by X-ray ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 30; Issue 5. Study of microstructure in vanadium–palladium alloys by X-ray diffraction technique ... Present study considers microstructural characterization of vanadium-based palladium (V–Pd) alloys, which are widely used in marine environment due to their high ...

  18. INFLUENCE OF ADDITIVES ON THE STRUCTURE FORMING OF ECONOMICALLY-ALLOYED WEAR RESISTING STEEL

    Directory of Open Access Journals (Sweden)

    A. I. Garost

    2007-01-01

    Full Text Available The characteristics of vanadium and nitrogencontaining economically-alloyed wear-resisting steels are investigated. The micro-composition and nature of nonmetallic impurities of steels with lowered content of manganese are studied. The optimal compositions of alloys for castings are offered.

  19. Microstructure and properties of Ti–Nb–V–Mo-alloyed high ...

    Indian Academy of Sciences (India)

    The correlations of microstructure, hardness and fracture toughness of high chromium cast iron with the addition of alloys (titanium, vanadium, niobium and molybdenum) were investigated. The results indicated that the as-cast microstructure changed from hypereutectic, eutectic to hypoeutectic with the increase of alloy ...

  20. Crystallization of Low-alloyed Construction Cast Steel Modified with V and Ti

    OpenAIRE

    Studnicki A.; Kondracki M.; Szajnar J.; Wróbel T.

    2013-01-01

    In this paper crystallization studies of low-alloyed construction cast steel were presented for different additions of chromium, nickel and molybdenum modified with vanadium and titanium. Studies were conducted using developed TDA stand, which additionally enabled evaluation of cooling rate influence on crystallization process of investigated alloys.

  1. Crystallization of Low-alloyed Construction Cast Steel Modified with V and Ti

    Directory of Open Access Journals (Sweden)

    Studnicki A.

    2013-09-01

    Full Text Available In this paper crystallization studies of low-alloyed construction cast steel were presented for different additions of chromium, nickel and molybdenum modified with vanadium and titanium. Studies were conducted using developed TDA stand, which additionally enabled evaluation of cooling rate influence on crystallization process of investigated alloys.

  2. Vertical Administration of Vanadium through Lactation Induces ...

    African Journals Online (AJOL)

    The work investigated the protective role of vitamin E on vanadium induced neurotoxicity. Three adult female rats were divided into three groups, A-C with each dam and her pups forming a group. Group A served as control. The dam in Group B was given 3mg/kg b.w./day of vanadium from PND 1 while the Group C dam ...

  3. Effect of organic additives on positive electrolyte for vanadium redox battery

    Energy Technology Data Exchange (ETDEWEB)

    Li Sha [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: lisha_csu@163.com [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2011-06-30

    Highlights: > Four organics as electrolyte additives of vanadium redox battery. > Changes are examined in the electrochemical properties of vanadium redox battery. > D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. > The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO{sup 2+} ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

  4. Vanadium speciation by chromatographic separation of V(IV) and V ...

    African Journals Online (AJOL)

    A new method for vanadium speciation has been developed. The method is based on chromatographic separation of vanadium(IV) and vanadium(V) in acidic medium followed by the determination with ICP-OES. Vanadium species exist in acidic solution (pH < 3) as VO2+ for vanadium(IV) and VO2 + for vanadium(V).

  5. Vanadium in landscape components of western Transbaikalia

    Science.gov (United States)

    Kashin, V. K.

    2017-10-01

    Vanadium in soil-forming rocks, soils, and vegetation of forest-steppe, steppe, and dry-steppe landscapes of Transbaikalia has been studied. The mean element contents in rocks and soils are equal to its mean natural abundances (clarke values). The content of vanadium in soils is strictly determined by its content in parent materials; its dependence on the vanadium concentration in plants and on the soil pH and humus is less pronounced. With respect to the coefficient of biological uptake by plants, vanadium is assigned to the group of elements of slight accumulation (0.10-0.33) on mineral soils and of moderate accumulation (1.1-1.5) on peat bog soils. The mean vanadium concentration in steppe, meadow, and cultivated vegetation exceeds the norm for animals by 1.7-2.6 times but does not rich toxic levels. Vanadium uptake by plants is most intensive in meadow cenoses and is less intensive in dry-steppe cenoses.

  6. Absorption of hydrogen in vanadium, enhanced by ion bombardment; Ionenbeschussunterstuetzte Absorption des Wasserstoffs in Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

    1998-12-31

    Prior to hydrogen implantation into vanadium, the vanadium specimen usually is exposed to an activation process and is then heated at 1 atm hydrogen to temperatures between 500 and 600 C, subsequently cooled down in several steps. Within this temperature range, hydrogen solubility increases with declining temperature. A decisive factor determining hydrogen absorption is the fact that at temperatures above 250 C, oxygen desorbs from the material surface and thus no longer inhibits hydrogen absorption. Therefore a different approach was chosen for the experiments reported: Hydrogen absorption under UHV conditions at room temperature. After the usual activation process, the vanadium surface was cleaned by 5 keV Ar{sup +} ion bombardment. Thus oxygen absorption at the specimen surface (and new reactions with oxygen from the remaining gas) could be avoided, or removed. By means of thermal desorption mass spectrometry (TDMS), hydrogen absorption as a function of argon ion dose was analysed. TDMS measurements performed for specimens treated by ion bombardment prior to H{sup 2} exposure showed two H{sup 2} desorption peaks, in contrast to the profiles measured with specimens not exposed to ion bombardment. It is assumed that the ion bombardment disturbs the crystal structure so that further sites for hydrogen absorption are produced. (orig./CB) [Deutsch] Bei der Beladung von Vandium mit Wasserstoff wird ueblicherweise die Probe nach einer Aktivierungsprozedur bei 1 atm Wasserstoff auf Temperaturen im Bereich von 500 bis 600 C hochgeheizt und danach schrittweise abgekuehlt. In diesem Temperaturbereich nimmt die Wasserstoffloeslichkeit mit abnehmender Temperatur zu. Entscheidend fuer die Beladung ist aber auch die Tatsache, dass bei Temperaturen groesser 250 C Sauerstoff von der Oberflaeche desorbiert und dadurch die Absorption von Wasserstoff nicht mehr blockieren kann. Im Rahmen der hier beschriebenen Untersuchungen sollte die Wasserstoffbeladung unter UHV-Bedingungen bei

  7. Studies on separation and purification of fission (99)Mo from neutron activated uranium aluminum alloy.

    Science.gov (United States)

    Rao, Ankita; Kumar Sharma, Abhishek; Kumar, Pradeep; Charyulu, M M; Tomar, B S; Ramakumar, K L

    2014-07-01

    A new method has been developed for separation and purification of fission (99)Mo from neutron activated uranium-aluminum alloy. Alkali dissolution of the irradiated target (100mg) results in aluminum along with (99)Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)3, iodine as AgI/AgIO3 and molybdenum as Mo-α-benzoin oxime. Ruthenium is separated by volatilization as RuO4 and final purification of (99)Mo was carried out using anion exchange method. The radiochemical yield of fission (99)Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Determination of activation energy for crystallizations in Ni-Cu-P amorphous alloys

    Science.gov (United States)

    Yu, Jinku; Qiao, Qi; Niu, Dongying; Jia, Qihua; Wang, Dongdong; Liu, Runhai

    2012-09-01

    The effect of plastic deformation on the crystallization kinetics of the ternary Ni-Cu-P amorphous alloy coatings prepared by electroless plating was investigated using differential scanning calorimetry. It was shown that the effective crystallization activation energy of the amorphous coatings is pronouncedly affected by the plastic deformation, indicating a decreasing tendency with deformation, the effective activation energy decreases from 199.02 to 163.71 kJ mol-1 as the plastic deformation from 0% to 40%. And, accordingly, this leads to the decrease of crystallization temperature. Analyses were presented to discuss the possible mechanism for the notable effects of plastic deformation on the crystallization kinetics of the amorphous coatings.

  9. Understanding the effect of steps, strain, poisons, and alloying: Methane activation on Ni surfaces

    DEFF Research Database (Denmark)

    Abild-Pedersen, Frank; Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2005-01-01

    It is shown that a single parameter characterizing the electronic structure of a transition metal surface, the d-band center (epsilon(d)), can be used to provide a unified description of a range of phenomena in heterogeneous catalysis. Using methane activation on Ni surfaces as an example, we show...... that variations in epsilon(d) can be used to quantitatively describe variations in the activation energy when the surface structure is changed, when the coverage of carbon is changed, when the surface is strained, when the surface is alloyed, and when the surface is poisoned by sulfur. The d-band center is......, therefore, a very general descriptor of the reactivity of a surface....

  10. Bioaccumulation of Vanadium by Vanadium-Resistant Bacteria Isolated from the Intestine of Ascidia sydneiensis samea.

    Science.gov (United States)

    Romaidi; Ueki, Tatsuya

    2016-06-01

    Isolation of naturally occurring bacterial strains from metal-rich environments has gained popularity due to the growing need for bioremediation technologies. In this study, we found that the vanadium concentration in the intestine of the vanadium-rich ascidian Ascidia sydneiensis samea could reach 0.67 mM, and thus, we isolated vanadium-resistant bacteria from the intestinal contents and determined the ability of each bacterial strain to accumulate vanadium and other heavy metals. Nine strains of vanadium-resistant bacteria were successfully isolated, of which two strains, V-RA-4 and S-RA-6, accumulated vanadium at a higher rate than did the other strains. The maximum vanadium absorption by these bacteria was achieved at pH 3, and intracellular accumulation was the predominant mechanism. Each strain strongly accumulated copper and cobalt ions, but accumulation of nickel and molybdate ions was relatively low. These bacterial strains can be applied to protocols for bioremediation of vanadium and heavy metal toxicity.

  11. Antibacterial activity, corrosion resistance and wear behavior of spark plasma sintered Ta-5Cu alloy for biomedical applications.

    Science.gov (United States)

    Cui, Jing; Zhao, Liang; Zhu, Weiwei; Wang, Bi; Zhao, Cancan; Fang, Liming; Ren, Fuzeng

    2017-10-01

    Tantalum has been widely used in orthopedic and dental implants. However, the major barrier to the extended use of such medical devices is the possibility of bacterial adhesion to the implant surface which will cause implant-associated infections. To solve this problem, bulk Ta-5Cu alloy has been fabricated by a combination of mechanical alloying and spark plasma sintering. The effect of the addition of Cu on the hardness, antibacterial activity, cytocompatibility, corrosion resistance and wear performance was systematically investigated. The sintered Ta-5Cu alloy shows enhanced antibacterial activity against E. Coli due to the sustained release of Cu ions. However, the addition of Cu would produce slight cytotoxicity and decrease corrosion resistance of Ta. Furthermore, pin-on-disk wear tests show that Ta-5Cu alloy has a much lower coefficient of friction but a higher wear rate and shows a distinct wear mode from that of Ta upon sliding against stainless steel 440C. Wear-induced plastic deformation leads to elongation of Ta and Cu grains along the sliding direction and nanolayered structures were observed upon approaching the sliding surface. The presence of hard oxides also shows a profound effect on the plastic flow of the base material and results in localized vortex patterns. The obtained results are expected to provide deep insights into the development of novel Ta-Cu alloy for biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Synthesis and anti-bacterial activity of Cu, Ag and Cu-Ag alloy nanoparticles: A green approach

    Energy Technology Data Exchange (ETDEWEB)

    Valodkar, Mayur; Modi, Shefaly; Pal, Angshuman [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390002, Gujarat (India); Thakore, Sonal, E-mail: drsonalit@gmail.com [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390002, Gujarat (India)

    2011-03-15

    Research highlights: {yields} Synthesis of novel nanosized copper-silver alloys of different compositions. {yields} Completely green approach for synthesis of water soluble bimetallic nanoparticle. {yields} Interesting anti-bacterial activity of as synthesized metal and alloy nanoparticle. -- Abstract: Metallic and bimetallic nanoparticles of copper and silver in various proportions were prepared by microwave assisted chemical reduction in aqueous medium using the biopolymer, starch as a stabilizing agent. Ascorbic acid was used as the reducing agent. The silver and copper nanoparticles exhibited surface plasmon absorption resonance maxima (SPR) at 416 and 584 nm, respectively; while SPR for the Cu-Ag alloys appeared in between depending on the alloy composition. The SPR maxima for bimetallic nanoparticles changes linearly with increasing copper content in the alloy. Transmission electron micrograph (TEM) showed monodispersed particles in the range of 20 {+-} 5 nm size. Both silver and copper nanoparticles exhibited emission band at 485 and 645 nm, respectively. The starch-stabilized nanoparticles exhibited interesting antibacterial activity with both gram positive and gram negative bacteria at micromolar concentrations.

  13. Adsorption of Vanadium (V) from SCR Catalyst Leaching Solution and Application in Methyl Orange.

    Science.gov (United States)

    Sha, Xuelong; Ma, Wei; Meng, Fanqing; Wang, Ren; Fuping, Tian; Wei, Linsen

    2016-12-01

      In this study, we explored an effective and low-cost catalyst and its adsorption capacity and catalytic capacity for Methyl Orange Fenton oxidation degradation were investigated. The catalyst was directly prepared by reuse of magnetic iron oxide (Fe3O4) after saturated adsorption of vanadium (V) from waste SCR (Selective Catalytic Reduction) catalyst. The obtained catalyst was characterized by FTIR, XPS and the results showed that vanadium (V) adsorption process of Fe3O4 nanoparticles was non-redox reaction. The effects of pH, adsorption kinetics and equilibrium isotherms of adsorption were assessed. Adsorption of vanadium (V) ions by Fe3O4 nanoparticles could be well described by the Sips isotherm model which controlled by the mixed surface reaction and diffusion (MSRDC) adsorption kinetic model. The results show that vanadium (V) was mainly adsorbed on external surface of the Fe3O4 nanoparticles. The separation-recovering tungsten (VI) and vanadium (V) from waste SCR catalyst alkaline solution through pH adjustment was also investigated in this study. The results obtained from the experiments indicated that tungsten (VI) was selectively adsorbed from vanadium (V)/tungsten (VI) mixed solution in certain acidic condition by Fe3O4 nanoparticle to realize their recovery. Tungsten (V) with some impurity can be obtained by releasing from adsorbent, which can be confirmed by ICP-AES. The Methyl Orange degradation catalytic performance illustrated that the catalyst could improve Fenton reaction effectively at pH = 3.0 compare to Fe3O4 nanoparticles alone. Therefore, Fe3O4 nanoparticle adsorbed vanadium (V) has a potential to be employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the decoloration efficiency of Methyl Orange.

  14. Functional and morphological olfactory bulb modifications in mice after vanadium inhalation.

    Science.gov (United States)

    Colín-Barenque, Laura; Pedraza-Chaverri, Jose; Medina-Campos, Omar; Jimenez-Martínez, Ruben; Bizarro-Nevares, Patricia; González-Villalva, Adriana; Rojas-Lemus, Marcela; Fortoul, Teresa I

    2015-02-01

    Neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, have olfaction impairment. These pathologies have also been linked to environmental pollutants. Vanadium is a pollutant, and its toxic mechanisms are related to the production of oxidative stress. In this study, we evaluated the effects of inhaled vanadium on olfaction, the olfactory bulb antioxidant, through histological and ultrastructural changes in granule cells. Mice in control group were made to inhale saline; the experimental group inhaled 0.02-M vanadium pentoxide (V2O5) for 1 hr twice a week for 4 weeks. Animals were sacrificed at 1, 2, 3, and 4 weeks after inhalation. Olfactory function was evaluated by the odorant test. The activity of glutathione peroxidase (GPx) and glutathione reductase (GR) was assayed in olfactory bulbs and processed for rapid Golgi method and ultrastructural analysis. Results show that olfactory function decreased at 4-week vanadium exposure; granule cells showed a decrease in dendritic spine density and increased lipofuscin, Golgi apparatus vacuolation, apoptosis, and necrosis. The activity of GPx and GR in the olfactory bulb was increased compared to that of the controls. Our results demonstrate that vanadium inhalation disturbs olfaction, histology, and the ultrastructure of the granule cells that might be associated with oxidative stress, a risk factor in neurodegenerative diseases. © 2014 by The Author(s).

  15. Different effects of vanadium ions on some DNA-metabolizing enzymes. [Calves, Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Sabbioni, E.; Clerici, L.; Brazzelli, A.

    The effects of vanadium on some enzymes involved in DNA metabolism were investigated in vitro. Vanadate (V) ions competitively inhibit calf thymus terminal deoxynucleotidyl transferase with K/sub i/ = 2.5 ..mu..M. A binding of vanadium to the enzyme with no change of the amount of the Zn constituent of the protein was found at concentrations of vanadate causing inhibition. The catalytic activity of mammalian DNA polymerase ..cap alpha.. was also inhibited by vanadate ions at an I/sub 50/ of 60 ..mu..M, while the bacterial (E. coli) DNA polymerase 1 was affected to the same extent only when the concentration of vanadate was raised to about 0.5 mM. In contrast to the inhibitory effects caused by vanadium on the nucleotidyl transferases, concentrations of pentavalent vanadium ions of the order of 10 ..mu..M increase 2.4-fold the hydrolytic activity of deoxyribonuclease I from bovine pancreas. These findings suggest that vanadium can interact with enzymes involved in nucleic acid metabolism.

  16. Chemical conversion coating for protecting magnesium alloys from corrosion

    Science.gov (United States)

    Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh; Hornish, Peter; Jain, Mohit

    2016-01-05

    A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds as self-healing moieties to defect sites, thus providing active corrosion protection.

  17. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  18. Infrared Brazing of Ti50Ni50 Shape Memory Alloy and Inconel 600 Alloy with Two Ag-Cu-Ti Active Braze Alloys

    Science.gov (United States)

    Shiue, Ren-Kae; Wu, Shyi-Kaan; Yang, Sheng-Hao

    2017-02-01

    Infrared brazing of Ti50Ni50 SMA and Inconel 600 alloy using Cusil-ABA and Ticusil filler metals has been investigated. The joints were dominated by Ag-Cu eutectic with proeutectic Cu in the Cusil-ABA brazed joint and with proeutectic Ag in the Ticusil one. A continuous curved belt composed of a Ni3Ti layer and a (Cu x Ni1- x )2Ti layer formed in the brazed Ti50Ni50/Ticusil/Inconel 600 joint. On the Ti50Ni50 SMA side, an intermetallic layer of (Cu x Ni1- x )2Ti formed in all joints, with x values around 0.81 and 0.47. Layers of (Cu x Ni1- x )2Ti, Ni3Ti, and mixed Ni3Ti and Ni2Cr intermetallics were observed next to the Inconel 600 substrate in the brazed Ti50Ni50/Cusil-ABA/Inconel 600 joint. The maximum shear strengths of the joints using the Cusil-ABA filler metal and the Ticusil filler metal were 324 and 300 MPa, respectively. In the Cusil-ABA brazed joint, cracks with cleavage-dominated fracture propagated along the (Cu x Ni1- x )2Ti interfacial layer next to the Ti50Ni50 SMA substrate. In the Ticusil brazed joint, ductile dimple fracture occurred in the Ag-rich matrix near the Inconel 600 alloy substrate. The absence of a detrimental Ti-Fe-(Cu) layer on the Inconel 600 substrate side can effectively improve the shear strength of the joint.

  19. Solvothermal synthesis of vanadium phosphates in the form of xerogels, aerogels and mesostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sydorchuk, V.; Zazhigalov, V. [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine); Khalameida, S., E-mail: svkhal@ukr.net [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine); Diyuk, E. [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine); Skubiszewska-Zieba, J.; Leboda, R. [Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031 Lublin (Poland); Kuznetsova, L. [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine)

    2010-09-15

    Regularities and peculiarities of physicochemical changes, first of all phase transformations, during solvothermal treatment (with conventional and microwave heating) of the vanadium pentoxide and orthophosphoric acid mixture in organic solvents in the presence of reducing agents have been studied. Hemihydrate of vanadium hydrophosphate - the precursor of vanadium pyrophosphate, the active phase for n-butane to maleic anhydride oxidation, and ion exchanger with variable physicochemical characteristics, i.e. crystal structure, specific surface area, crystallite size and acidic properties - has been synthesized in the temperature range 170-200 {sup o}C. The obtained phases were examined using XRD, DTA-TG, SEM, FTIR spectroscopy, nitrogen adsorption as well as gas chromatographic determination of acidity through organic bases adsorption. The catalytic activity of prepared samples for n-butane oxidation has been investigated.

  20. Iron diminishes the in vitro biological effect of vanadium.

    Science.gov (United States)

    Mechanistic pathways underlying inflammatory injury following exposures to vanadium-containing compounds are not defined. We tested the postulate that the in vitro biological effect of vanadium results from its impact on iron homeostasis. Human bronchial epithelial (HBE) cells ex...

  1. Determination of the activation energy for SCC crack growth for Alloy 182 weld in a PWR environment

    Energy Technology Data Exchange (ETDEWEB)

    Alexandreanu, B.; Chopra, O.K.; Shack, W.J. [Argonne National Lab., Nuclear Engineering Div., Argonne, Illinois (United States)

    2007-07-01

    The objective of this work was to determine the activation energy for stress corrosion cracking growth rates in a simulated PWR water environment for Alloy 182 weld metals. For this purpose, the crack growth rates (CGRs) of two heats of Alloy 182 were measured as a function of temperature between 290{sup o}C and 350{sup o}C. The difference in electrochemical potential between the specimen and the Ni/NiO line was maintained constant at each temperature by adjusting the hydrogen overpressure on the water supply tank. The CGR data as a function of temperature yielded activation energies of 252 kJ/mol for a double-J weld and 189 kJ/mol for a deep-groove weld. The data reported here and those in the literature suggest that the average activation energy for Alloy 182 welds is on the order of 220-230 kJ/mol, higher than the 130 kJ/mol commonly used for Alloy 600. The consequences of using a larger value of activation energy for SCC CGR data analysis are discussed. (author)

  2. Activation Energy Measurement of Oxygen Ordering in a Nb-Ti Alloy by Anelastic Relaxation

    Directory of Open Access Journals (Sweden)

    Niemeyer T.C.

    2002-01-01

    Full Text Available Metals with bcc structure are able to dissolve large amounts of interstitial element atoms in the form of oxygen. These atoms diffuse through the lattice by jumping into octahedral sites with equivalent symmetry, causing strong alterations in the anelastic behavior. This paper reports on a study of Snoek relaxation in Nb-Ti alloys with oxygen in solid solution, based on internal friction as a function of temperature. The internal friction measurements were taken in a torsion pendulum operating at temperatures in the range of 350 to 650 K, with frequencies varying from 6 to 36 Hz. The results show relaxation spectra in which thermally activated relaxation peaks produced by the stress-induced ordering of oxygen atoms around niobium atoms of the metallic matrix were identified.

  3. Investigation of photocatalytic activity of titanium dioxide coating deposited on aluminium alloy substrate by plasma technique

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Soyama, Juliano; Dirscherl, Kai

    2011-01-01

    . The photocatalytic process is initiated by UV-light in TiO2 which creates electron-/hole pairs in the conduction band (CB) and valence band (VB) of TiO2, respectively. The electron/hole pairs generated have sufficient energy to cause reduction and oxidation on its surface providing the self-cleaning effect....... Literature consists of large number of publications on titanium dioxide coating for self-cleaning applications, with glass as the main substrate. Only little work is available on TiO2 coating of metallic alloys used for engineering applications. Engineering materials, such as light-weight aluminium and steel...... of the coating strongly influences the photocatalytic properties. In general, the photocatalytic activity increased with thickness. Quantification of images scanned with Atomic Force Microscope (AFM) revealed that there is a linear relationship between the thickness of the coating and the average cell size...

  4. Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag.

    Science.gov (United States)

    Chartier, D; Muzeau, B; Stefan, L; Sanchez-Canet, J; Monguillon, C

    2017-03-15

    Magnesium alloys and graphite from spent nuclear fuel have been stored together in La Hague plant. The packaging of these wastes is under consideration. These wastes could be mixed in a grout composed of industrially available cement (Portland, calcium aluminate…). Within the alkaline pore solution of these matrixes, magnesium alloys are imperfectly protected by a layer of Brucite resulting in a slow corrosion releasing hydrogen. As the production of this gas must be considered for the storage safety, and the quality of wasteform, it is important to select a cement matrix capable of lowering the corrosion kinetics. Many types of calcium based cements have been tested and most of them have caused strong hydrogen production when magnesium alloys and graphite are conditioned together because of galvanic corrosion. Exceptions are binders based on alkali hydroxide activated ground granulated blast furnace slag (BFS) which are presented in this article. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Protection against vanadium-induced testicular toxicity by testosterone propionate in rats.

    Science.gov (United States)

    Chandra, Amar K; Ghosh, Rituparna; Chatterjee, Aparajita; Sarkar, Mahitosh

    2010-07-01

    Vanadium is a well recognized industrial hazard known to adversely affect male reproductive functions. The intricate mechanistic aspects of this metal and the role of oxidative stress in the deterioration of testicular functions are investigated in the current study. The experiment also focused on the effects of testosterone propionate in testicular and sperm functions in the rat intoxicated with vanadate. Vanadium exposure resulted in a more prominent spermatogenic arrest and consistently abolished the conversion of round to mature spermatids along with decreased epididymal sperm number and increased percentage of abnormal sperm. This is followed by a precipitous decline in the level of serum testosterone and gonadotropins and consequently the testicular steroidogenic and antioxidant enzymes were inhibited. Vanadium induces degeneration in the genital organs of rats and exhibits high indices of lipid oxidative damage. In response to exogenous testosterone propionate (TP) administration, spermatogonial cell populations remained suppressed, while the spermatogenesis was restored quantitatively. In contrast, the hormone treatment had no effect on the dramatically decreased serum FSH level after vanadate treatment. Moreover, TP could ameliorate the toxicity, as indicated by decreased testicular lipid peroxidation with marginal but significant increase in the activities of all the measured enzymes following vanadate-treatment. Taken together all these studies establish that vanadium is a testicular toxicant that perturbs the male reproductive system adversely. However, hormone replacement therapy by testosterone propionate may provide partial protection. The results suggest the feasibility of using endocrine regimens to impede deleterious effects of vanadium on the male reproductive system.

  6. Effects of Microwave Roasting on the Kinetics of Extracting Vanadium from Vanadium Slag

    Science.gov (United States)

    Zhang, Guoquan; Zhang, Ting-an; Lü, Guozhi; Zhang, Ying; Liu, Yan; Zhang, Weiguang

    2016-02-01

    The kinetics of extracting vanadium (V) from microwave-roasted (MR) vanadium slag (V-slag) with concentrated H2SO4 were investigated. The microwave irradiation experiments were performed in a modified microwave muffle furnace at temperatures ranging from 150°C to 750°C. The x-ray diffraction analysis indicated that the spinel phase of the V-slag is destroyed after 10 min of roasting. The phase composition of the V-slag was changed by the roasting process, and a new Fe2O3 phase appeared in the samples roasted at higher temperatures. Compared to the raw slag, the surface area, pore volume, and pore size of the MR slags were much lower. It was easier to leach V from the MR samples than the raw sample with the H2SO4 solution, and the leaching process was accelerated in the MR samples. When the V-slag was roasted at 150°C and 350°C (MR@150 and MR@350, respectively), the apparent activation energy was decreased from 77.65 kJ/mol to 68.42 kJ/mol and 66.68 kJ/mol, respectively. The process of leaching V from the raw and MR slags was controlled by both the surface chemical reactions and internal diffusion. The reaction orders of the raw, MR@150, and MR@350 V-slags, with respect to the H2SO4 concentration, were 1.23, 0.75, and 0.70, respectively.

  7. Self-activated mesh device using shape memory alloy for periosteal expansion osteogenesis.

    Science.gov (United States)

    Yamauchi, Kensuke; Takahashi, Tetsu; Tanaka, Kenko; Nogami, Shinnosuke; Kaneuji, Takeshi; Kanetaka, Hiroyasu; Miyazaki, Toshiki; Lethaus, Bernd; Kessler, Peter

    2013-07-01

    The present study evaluated the use of this self-activated shape memory alloy (SMA) device, with a focus on its effects in the region under the periosteum. Twelve Japanese white rabbits were used in this study. The device was inserted under the periosteum at the forehead. In the experimental group, the device was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the device was only inserted under the periosteum. After 14 days, the screw was removed and the mesh was activated in the experimental group. Rabbits were sacrificed 5 and 8 weeks after the operation and newly formed bone was histologically and radiographically evaluated. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at each consolidation period. Histologically, some newly formed bone was observed and most of the subperiosteal space underneath the device was filled with fibrous tissue, and a thin layer of immature bone was observed in the control group. In the experimental group, multiple dome-shaped bones, outlined by thin and scattered trabeculae, were clearly observed under the SMA mesh device. The use of self-activated devices for the periosteal expansion technique may make it possible to avoid donor site morbidity, trans-skin activation rods, any bone-cutting procedure, and the following intermittent activation procedure. Copyright © 2013 Wiley Periodicals, Inc.

  8. Applicability of Shape Memory Alloy Wire for an Active, Soft Orthotic

    Science.gov (United States)

    Stirling, Leia; Yu, Chih-Han; Miller, Jason; Hawkes, Elliot; Wood, Robert; Goldfield, Eugene; Nagpal, Radhika

    2011-07-01

    Current treatments for gait pathologies associated with neuromuscular disorders may employ a passive, rigid brace. While these provide certain benefits, they can also cause muscle atrophy. In this study, we examined NiTi shape memory alloy (SMA) wires that were annealed into springs to develop an active, soft orthotic (ASO) for the knee. Actively controlled SMA springs may provide variable assistances depending on factors such as when, during the gait cycle, the springs are activated; ongoing muscle activity level; and needs of the wearer. Unlike a passive brace, an active orthotic may provide individualized control, assisting the muscles so that they may be used more appropriately, and possibly leading to a re-education of the neuro-motor system and eventual independence from the orthotic system. A prototype was tested on a suspended, robotic leg to simulate the swing phase of a typical gait. The total deflection generated by the orthotic depended on the knee angle and the total number of actuators triggered, with a max deflection of 35°. While SMA wires have a high energy density, they require a significant amount of power. Furthermore, the loaded SMA spring response times were much longer than the natural frequency of an average gait for the power conditions tested. While the SMA wires are not appropriate for correction of gait pathologies as currently implemented, the ability to have a soft, actuated material could be appropriate for slower timescale applications.

  9. Nanoporous PdZr surface alloy as highly active non-platinum electrocatalyst toward oxygen reduction reaction with unique structure stability and methanol-tolerance

    Science.gov (United States)

    Duan, Huimei; Xu, Caixia

    2016-06-01

    Nanoporous (NP) PdZr alloy with controllable bimetallic ratio is successfully fabricated by a simple dealloying method. By leaching out the more reactive Al from PdZrAl precursor alloy, NP-PdZr alloy with smaller ligament size was generated, characterized by the nanoscaled interconnected network skeleton and hollow channels extending in all three dimensions. Upon voltammetric scan in acid solution, the dissolution of surface Zr atoms generates the highly active Pd-Zr surface alloy with a nearly pure Pd surface and Pd-Zr alloy core. The NP-Pd80Zr20 surface alloy exhibits markedly enhanced specific and mass activities as well as higher catalytic stability toward oxygen reduction reaction (ORR) compared with NP-Pd and the state-of-the-art Pt/C catalysts. In addition, the NP-Pd80Zr20 surface alloy shows a better selectivity for ORR than methanol in the 0.1 M HClO4 and 0.1 M methanol mixed solution. X-ray photoelectron spectroscopy and density functional theory calculations both demonstrate that the weakened Pd-O bond and improved ORR performances in turn depend on the downshifted d-band center of Pd due to the alloying Pd with Zr (20 at.%). The as-made NP-PdZr alloy holds prospective applications as a cathode electrocatalyst in fuel-cell-related technologies with the advantages of superior overall ORR performances, unique structure stability, and easy preparation.

  10. 77 FR 51825 - Ferrovanadium and Nitrided Vanadium From Russia

    Science.gov (United States)

    2012-08-27

    ... COMMISSION Ferrovanadium and Nitrided Vanadium From Russia Determination On the basis of the record \\1... antidumping duty order on ferrovanadium and nitrided vanadium from Russia would not be likely to lead to... contained in USITC Publication 4345 (August 2012), entitled Ferrovanadium and Nitrided Vanadium from Russia...

  11. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

    Directory of Open Access Journals (Sweden)

    Oluwabusayo Folarin

    2016-01-01

    Full Text Available Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal.

  12. Determination of Leachable Vanadium (V) in Sediment | Mampuru ...

    African Journals Online (AJOL)

    A method for speciation of vanadium in solid samples was developed for quantification of vanadium(+5) in solid samples of sediment Certified Reference Materials (CRM) PACS-2 and MESS-3 (Trace Elements in Sediments) of known total vanadium content. The method relies on a classical analytical chemistry procedure ...

  13. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice.

    Science.gov (United States)

    Folarin, Oluwabusayo; Olopade, Funmilayo; Onwuka, Silas; Olopade, James

    2016-01-01

    Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal.

  14. Chemical and mechanical interactions of interstitials with vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    DiStefano, J.R.; Chitwood, L.D.; DeVan, J.H. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Oxidation studies of V-4Cr-4Ti were conducted in air and reduced oxygen partial pressures (10{sup 4}, 10{sup -5} and 10{sup -6} torr). Reaction rates were determined by weight change measurements and chemical analyses. Mechanical properties after the exposures were determined by room temperature tensile tests. In air at 400 and 500{degrees}C, oxide films form on the surface. Initially, rates are high but decrease with time reaching similiar values to those found in oxygen partial pressures at 10{sup -4}, 10{sup -5}, and 10{sup -6} torr. At 400{degrees}C, oxygen pick-up followed a logarithmic function of time and was confined to regions near the surface. Little change in room temperature tensile properties was noted for oxygen increase up to 1500 ppm. Thermal cycling specimens from 400{degrees}C to room temperature up to 14 times had no apparent effect on oxidation rate or tensile properties. At 500{degrees}C, oxygen pick-up appeared to follow a parabolic relation with time. Rates were {approx} 10 times those at 400{degrees}C and correspondingly larger oxygen increases occurred when compared with the 400{degrees}C tests after similiar time periods. This resulted in a significant decrease in total elongation after 240 h. At reduced oxygen partial pressures, rates were measured for times <100 h. Data are relatively sparse but generally show a slightly higher initial rate before slowing. At 400{degrees}C increases to {approx}200 ppm oxygen were found with no effect on room temperature elongation. At 500{degrees}C increase in oxygen of 2400 ppm after 50h/10{sup -5} torr resulted in a decrease of around 25% in room temperature elongation. By comparison, exposure to air at 500{degrees}C for 12 h caused nearly the same results.

  15. Differences of platelet adhesion and thrombus activation on amorphous silicon carbide, magnesium alloy, stainless steel, and cobalt chromium stent surfaces.

    Science.gov (United States)

    Hansi, Christopher; Arab, Amina; Rzany, Alexander; Ahrens, Ingo; Bode, Christoph; Hehrlein, Christoph

    2009-03-01

    Coronary stenting is considered to be the gold standard of percutaneous coronary interventions, because stents are able to reduce early and late elastic recoil (negative remodeling) and restenosis in comparison with balloon angioplasty alone. It is known that stent thrombogenicity and neointimal formation are determined by the surface characteristics of the stent platform, electrochemical features of the stent surface, and the degree of degradation after implantation. Metallic stents coated with amorphous silicon carbide and biodegradable stents made of magnesium alloy have been introduced clinically, but there are no data available comparing the biocompatibility of these novel stent materials with conventional stents. We demonstrate simple and reproducible in vitro methods assessing the rate of platelet adhesion and thrombus activation for biocompatibility tests of different stent surfaces. We show that amorphous silicon carbide and magnesium alloy stent surfaces markedly lower the rate of platelet adhesion and platelet/fibrin activation when compared with uncoated stainless steel or cobalt chromium alloy surfaces. Semiconductor materials on the stent surface reduce platelet and fibrin activation by increasing the critical electron gap to greater than 0.9 eV resulting in a lower electron transfer out of the stent material. Passive stent coatings with specific semiconducting properties such as amorphous silicon carbide or magnesium alloy reduce thrombogenicity and may improve biocompatibility of a stent platform.

  16. Application of factorial designs and Doehlert matrix in optimization of experimentalvariabl es associated with the preconcentration and determination of vanadium and copper in seawater by inductively coupled plasma optical emission spectrometry

    OpenAIRE

    Ferreira, Sergio Luis Costa; Queiroz, Adriana Santana; Fernandes, Marcelo Santiago; Hilda Costa dos Santos, Talma

    2002-01-01

    p. 1939–1950 In the present paper a procedure for preconcentration and determination of vanadium and copper in seawater using inductively coupled plasma optical emission spectrometry (ICP OES) is proposed, which is based on solid-phase extraction of vanadium (IV), vanadium (V) and copper (II) ions as 1-(2-pyridylazo)-2-naphthol (PAN) complexes by active carbon. The optimization process was carried out using two-level full factorials and Doehlert matrix designs. Four variables (PA...

  17. Fascinating and challenging role of tungstate promoted vanadium phosphate towards solvent free esterification of oleic acid.

    Science.gov (United States)

    Behera, Gobinda Chandra; Parida, K M

    2012-01-28

    A novel solid acid catalyst has been extensively used for the esterification reaction. Herein, tungstate promoted vanadium phosphate material is fabricated from its precursor, VOHPO(4)·0.5H(2)O and its catalytic activities and structure are investigated in detail. This kind of catalyst is, for the first time, applied for the effective production of biodiesel from fatty acids. Although vanadium phosphate has been extensively used in gas phase oxidation reactions, it has not drawn much attention for its application in liquid phase reactions. Our recent results indicate that vanadium phosphate is an effective, minimally polluting and re-usable catalyst that is highly suited to the production of biodiesel from fatty acids. This work extends the possibility of using VPO in other liquid phase reactions.

  18. Investigation of the electrospun carbon web as the catalyst layer for vanadium redox flow battery

    Science.gov (United States)

    Wei, Guanjie; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei

    2014-12-01

    Polyacrylonitrile (PAN) carbon nonwoven web consisting of 100-200 nm ultrafine fibers has been developed by electrospinning and subsequent carbonization process at 1000 °C for different times. The surface morphology, composition, structure, and electrical conductivity of the electrospun carbon webs (ECWs) as well as their electrochemical properties toward vanadium redox couples have been characterized. With the increasing of carbonization time, the electrochemical reversibility of the vanadium redox couples on the ECW is enhanced greatly. As the carbonization time increases up to 120 min, the hydrogen evolution is facilitated while the reversibility is promoted a little bit further. The excellent performance of ECW may be attributed to the conversion of fibers carbon structure and improvement of electrical conductivity. Due to the good electrochemical activity and freestanding 3-dimensional structure, the ECW carbonized for 90 min is used as catalyst layer in vanadium redox flow battery (VRFB) and enhances the cell performance.

  19. In vivo degradation behavior and biological activity of some new Mg-Ca alloys with concentration's gradient of Si for bone grafts

    Science.gov (United States)

    Trincă, Lucia Carmen; Fântânariu, Mircea; Solcan, Carmen; Trofin, Alina Elena; Burtan, Liviu; Acatrinei, Dumitru Mihai; Stanciu, Sergiu; Istrate, Bogdan; Munteanu, Corneliu

    2015-10-01

    Magnesium based alloys, especially Mg-Ca alloys, are biocompatible substrates with mechanical properties similar to those of bones. The biodegradable alloys of Mg-Ca provide sufficient mechanical strength in load carrying applications as opposed to biopolymers and also they avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. The main issue facing a biodegradable Mg-Ca alloy is the fast degradation in the aggressive physiological environment of the body. The alloy's corrosion is proportional with the dissolution of the Mg in the body: the reaction with the water generates magnesium hydroxide and hydrogen. The accelerated corrosion will lead to early loss of the alloy's mechanical integrity. The degradation rate of an alloy can be improved mainly through tailoring the composition and by carrying out surface treatments. This research focuses on the ability to adjust degradation rate of Mg-Ca alloys by an original method and studies the biological activity of the resulted specimens. A new Mg-Ca alloy, with a Si gradient concentration from the surface to the interior of the material, was obtained. The surface morphology was investigated using scanning electron microscopy (VegaTescan LMH II, SE detector, 30 kV), X-ray diffraction (X'Pert equipment) and energy dispersive X-ray (Bruker EDS equipment). In vivo degradation behavior, biological compatibility and activity of Mg-Ca alloys with/without Si gradient concentration were studied with an implant model (subcutaneous and bony) in rats. The organism response to implants was characterized by using radiological (plain X-rays and computed tomography), biochemical and histological methods of investigation. The results sustained that Si gradient concentration can be used to control the rate of degradation of the Mg-Ca alloys for enhancing their biologic activity in order to facilitate bone tissue repair.

  20. Interactions of Penicillium griseofulvum with inorganic and organic substrates: vanadium, lead and hexachlorocyclohexane

    Science.gov (United States)

    Ceci, Andrea; Pierro, Lucia; Riccardi, Carmela; Maggi, Oriana; Pinzari, Flavia; Gadd, Geoffrey Michael; Petrangeli Papini, Marco; Persiani, Anna Maria

    2015-04-01

    Soil is an essential and non-renewable resource for human beings and ecosystems. In recent years, anthropogenic activities mainly related to hydrocarbon fuel combustion, mining and industrial activities have increased the levels of vanadium in the environment, raising concern over its spread. Vanadium may be essential for some bacteria and fungi, but can have toxic effects at high concentrations. The pesticide lindane or γ-hexachlorocyclohexane (γ-HCH) and another two isomers of hexachlorocyclohexane (HCH), α-HCH, and β-HCH, were included as persistent organic pollutants in the Stockholm Convention in 2008, and their worldwide spread and toxic effects on organisms are severe environmental problems. Fungi play important roles in soil and can survive in high concentrations of toxic elements and pesticides by possessing mechanisms for the degradation, utilization and transformation of organic and inorganic substrates. The transformation of potentially toxic elements (PTEs), and degradation of chlorinated pesticides and other persistent organic pollutants may provide environmentally-friendly and economical approaches for environmental management and restoration. In this work, we have investigated the tolerance of a soil fungal species, Penicillum griseofulvum, to different hexachlorocyclohexane (HCH) isomers, α-HCH, β-HCH, δ-HCH and γ-HCH or lindane, and two PTEs, vanadium and lead in relation to growth responses and biotransformation. P. griseofulvum was isolated from soils with high levels of PTEs (including vanadium and lead), and HCH residues. P. griseofulvum was able to tolerate vanadium concentrations up to 5 mM, combinations of 2.5 mM vanadium and lead compounds, and was able to grow in the presence of a 4 mg L-1 mixture of α-HCH, β-HCH, δ-HCH and γ-HCH, and degrade these substrates. Tolerance mechanisms may explain the occurrence of fungi in polluted habitats: their roles in the biotransformation of metals and persistent organic pollutants may

  1. Design optimization study of a shape memory alloy active needle for biomedical applications.

    Science.gov (United States)

    Konh, Bardia; Honarvar, Mohammad; Hutapea, Parsaoran

    2015-05-01

    Majority of cancer interventions today are performed percutaneously using needle-based procedures, i.e. through the skin and soft tissue. The difficulty in most of these procedures is to attain a precise navigation through tissue reaching target locations. To overcome this challenge, active needles have been proposed recently where actuation forces from shape memory alloys (SMAs) are utilized to assist the maneuverability and accuracy of surgical needles. In the first part of this study, actuation capability of SMA wires was studied. The complex response of SMAs was investigated via a MATLAB implementation of the Brinson model and verified via experimental tests. The isothermal stress-strain curves of SMAs were simulated and defined as a material model in finite element analysis (FEA). The FEA was validated experimentally with developed prototypes. In the second part of this study, the active needle design was optimized using genetic algorithm aiming its maximum flexibility. Design parameters influencing the steerability include the needle's diameter, wire diameter, pre-strain and its offset from the needle. A simplified model was presented to decrease the computation time in iterative analyses. Integration of the SMA characteristics with the automated optimization schemes described in this study led to an improved design of the active needle. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  2. Analytic estimation and numerical modeling of actively cooled thermal protection systems with nickel alloys

    Directory of Open Access Journals (Sweden)

    Wang Xinzhi

    2014-12-01

    Full Text Available Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and numerical modeling are performed in this paper to investigate the behavior of an actively cooled thermal protection system. The analytic estimation is based on the electric analogy method and finite element analysis (FEA is applied to the numerical simulation. Temperature and stress distributions are obtained for the actively cooled channel walls with three kinds of nickel alloys with or with no thermal barrier coating (TBC. The temperature of the channel wall with coating has no obvious difference from the one with no coating, but the stress with coating on the channel wall is much smaller than that with no coating. Inconel X-750 has the best characteristics among the three Ni-based materials due to its higher thermal conductivity, lower elasticity module and greater allowable stress. Analytic estimation and numerical modeling results are compared with each other and a reasonable agreement is obtained.

  3. Antitumor Activity of Alloy and Core-Shell-Type Bimetallic AgAu Nanoparticles

    Science.gov (United States)

    Shmarakov, Igor; Mukha, Iuliia; Vityuk, Nadiia; Borschovetska, Vira; Zhyshchynska, Nelya; Grodzyuk, Galyna; Eremenko, Anna

    2017-05-01

    Nanoparticles (NPs) of noble metals, namely gold and silver, remain promising anticancer agents capable of enhancing current surgery- and chemotherapeutic-based approaches in cancer treatment. Bimetallic AgAu composition can be used as a more effective agent due to the synergetic effect. Among the physicochemical parameters affecting gold and silver nanoparticle biological activity, a primary concern relates to their size, shape, composition, charge, etc. However, the impact of metal components/composition as well as metal topological distribution within NPs is incompletely characterized and remains to be further elucidated and clarified. In the present work, we tested a series of colloidal solutions of AgAu NPs of alloy and core-shell type for an antitumor activity depending on metal molar ratios (Ag:Au = 1:1; 1:3; 3:1) and topological distribution of gold and silver within NPs (AucoreAgshell; AgcoreAushell). The efficacy at which an administration of the gold and silver NPs inhibits mouse Lewis lung carcinoma (LLC) growth in vivo was compared. The data suggest that in vivo antitumor activity of the studied NPs strongly depends on gold and silver interaction arising from their ordered topological distribution. NPs with Ag core covered by Au shell were the most effective among the NPs tested towards LLC tumor growth and metastasizing inhibition. Our data show that among the NPs tested in this study, AgcoreAushell NPs may serve as a suitable anticancerous prototype.

  4. Reduction of nitrates in Cucumis sativus L. seedlings II. Influence of tungsten and vanadium on nitrate reductase and adenosine triphosphatase activities

    Directory of Open Access Journals (Sweden)

    Józef Buczek

    2014-01-01

    Full Text Available ATPases isolated from the roots of cucumber seedlings activated by Mg+2 ions in experiments in vitro, were fairly distinctly inhibited by Ca-2 ions, very slightly inhibited by fluorides and molybdenum ions while NO3- anions had no effect on the level of ATPase activity studied. Introduction into the nutrient of 10-4 M Na2WO4 or 10-3 M Na VO3 (inhibitors of nitrate reductase NR distinctly inhibited activity of the ATPase under study especially of fractions IIa and III, and inhibited NR activity and lowered uptake of NO3-. WO4-2 and VO3 inhibited to the same extent absorption and reduction of NO3- in the initial phase of NR induction, whereas at a later stage both inhibitors checked reduction to a greater degree than uptake of NO3-. The results indicate the possibility of certain ATPase participation in assimilating nitrates, and suggest that in the initial stage of biosynthesis of the NR enzyme system, activity of the enzyme is distinctly dependent upon NO3- transport and the level of NR activity limited by the amount of nitrate taken up. At a later an additional mechanism of NO3- transport probably functions, not connected with simultaneous reduction of nitrates. On the basis of results the Butz and Jackson (1977 hypothesis concerning a model for the absorption and reduction of NO3- by plant tissues is discussed.

  5. Study of thermal degradation of vanadium and titanium acetylacetonate derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Dyagileva, L.M.; Tsyganova, E.I.; Mar' in, V.P.; Aleksandrov, Yu.A. (Gor' kovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Khimii)

    1982-09-01

    Kinetics and products of vanadium (+3), vanadyl (+3) and titanium (+3) acetylacetonates thermal degradation have been studied in vapor phase in the closed system at 300-470 deg C. Gaseous composition of pyrolysis has been determined at different levels of decomposition. It is supposed that vanadium and metal vanadium mixed oxides become vanadium (+3) pyrolysis products. It is shown that metal oxidation level does not affect the thermal degradation rate. Central atom substitution leads to the change in thermal stability. Titanium (+3) acetylacetate derivatives are less stable than vanadium (+3) ones.

  6. Modification of halogen specificity of a vanadium-dependent bromoperoxidase.

    Science.gov (United States)

    Ohshiro, Takashi; Littlechild, Jennifer; Garcia-Rodriguez, Esther; Isupov, Michail N; Iida, Yasuaki; Kobayashi, Takushi; Izumi, Yoshikazu

    2004-06-01

    The halide specificity of vanadium-dependent bromoperoxidase (BPO) from the marine algae, Corallina pilulifera, has been changed by a single amino acid substitution. The residue R397 has been substituted by the other 19 amino acids. The mutant enzymes R397W and R397F showed significant chloroperoxidase (CPO) activity as well as BPO activity. These mutant enzymes were purified and their properties were investigated. The maximal velocities of CPO activities of the R397W and R397F enzymes were 31.2 and 39.2 units/mg, and the K(m) values for Cl(-) were 780 mM and 670 mM, respectively. Unlike the native enzyme, both mutant enzymes were inhibited by NaN(3). In the case of the R397W enzyme, the incorporation rate of vanadate into the active site was low, compared with the R397F and the wild-type enzyme. These results supported the existence of a specific halogen binding site within the catalytic cleft of vanadium haloperoxidases.

  7. Correlation between viscous-flow activation energy and phase diagram in four systems of Cu-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ning Shuang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bian Xiufang, E-mail: xfbian@sdu.edu.c [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Ren Zhenfeng [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2010-09-01

    Activation energy is obtained from temperature dependence of viscosities by means of a fitting to the Arrhenius equation for liquid alloys of Cu-Sb, Cu-Te, Cu-Sn and Cu-Ag systems. We found that the changing trend of activation energy curves with concentration is similar to that of liquidus in the phase diagrams. Moreover, a maximum value of activation energy is in the composition range of the intermetallic phases and a minimum value of activation energy is located at the eutectic point. The correlation between the activation energy and the phase diagrams has been further discussed.

  8. Protein adsorption steers blood contact activation on engineered cobalt chromium alloy oxide layers.

    Science.gov (United States)

    Milleret, Vincent; Buzzi, Stefano; Gehrig, Peter; Ziogas, Algirdas; Grossmann, Jonas; Schilcher, Katrin; Zinkernagel, Annelies S; Zucker, Arik; Ehrbar, Martin

    2015-09-01

    Biomaterials upon implantation are immediately covered by blood proteins which direct the subsequent blood activation. These early events determine the following cascade of biological reactions and consequently the long-term success of implants. The ability to modulate surface properties of biomaterials is therefore of considerable clinical significance. Goal of this study was an in-depth understanding of the biological response to cobalt chromium stent alloys with engineered surface oxide layers, which showed altered body reactions in vivo. We analyzed in vitro the biological events following initial blood contact on engineered cobalt chromium surfaces featuring said oxide layers. Surface-specific blood reactions were confirmed by scanning electron microscopy and the adsorbed protein layers were characterized by mass spectrometry. This powerful proteomics tool allowed the identification and quantification of over hundred surface-adhering proteins. Proteins associated with the coagulation cascade, platelet adhesion and neutrophil function correlated with the various blood surface activations observed. Furthermore, results of pre-coated surfaces with defined fibrinogen-albumin mixtures suggest that neutrophil adhesion was controlled by fibrinogen orientation and conformation rather than quantity. This study highlights the importance of controlling the biological response in the complex protein-implant surface interactions and the potential of the surface modifications to improve the clinical performance of medical implants. The blood contact activation of CoCr alloys is determined by their surface oxide layer properties. Modifications of the oxide layer affected the total amount of adsorbed proteins and the composition of the adsorbed protein layer. Additionally fibrinogen coatings mediated the surface-dependent neutrophil adhesion in a concentration-independent manner, indicating the influence of conformation and/or orientation of the adsorbed protein. Despite the

  9. Vanadium bioavailability in soils amended with blast furnace slag

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Maja A., E-mail: maja.larsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Baken, Stijn, E-mail: stijn.baken@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Smolders, Erik, E-mail: erik.smolders@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Cubadda, Francesco, E-mail: francesco.cubadda@iss.it [Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome 00161 (Italy); Gustafsson, Jon Petter, E-mail: jon-petter.gustafsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Brinellvägen 28, 100 44 Stockholm (Sweden)

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg{sup −1}) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment.

  10. Cold dynamic compaction of pre-alloyed titanium and activated sintering

    Energy Technology Data Exchange (ETDEWEB)

    Raybould, D.

    1983-01-01

    The use of dynamic compaction has been found to allow the cold consolidation of Ti-6Al-4V to densities of 99% T.D. Although full interparticle welding was not attained, bonding was found to occur during a low temperature sintering operation; below the ..beta.. transition. The high strengths and toughness values thus obtained are due to an activation of the sintering operation caused by the removal of surface oxide and good metal to metal bonds formed during dynamic compaction, when extensive local shearing of the particles surface occurs. This activation of sintering allows a control of microstructure and in particular, avoidance of embrittling phases. During compaction the passage of the shock wave results in the formation of a shocked structure. Spherical powders usually compact dynamically to characteristic shapes. The shock hardening allows the particle through which the shock has passed to deform the subsequent particle it impacts. This is rarely observed with the titanium alloy, indicating the low shock hardening or high initial hardness of the powders. Areas of interparticle melting were observed, but appeared to be the melting of a third particle rather than melting and bonding between particles.

  11. Investigation of the interaction of benzene with vanadium-molybdenum oxide catalysts by programmed thermal desorption

    Energy Technology Data Exchange (ETDEWEB)

    Belokopytov, Yu.V.; Pyatnitskii, Yu.I.; Grebennikov, Yu.N.

    1985-09-01

    Programmed thermal desorption was used to investigate the interaction of benzene with vanadium-molybdenum oxide catalysts. It was established that the amount of maleic anhydride desorbed from the catalyst surface depends on the catalyst composition and that it varies with its activity and selectivity.

  12. A comprehensive model for the supported vanadium oxide catalyst: The umbrella model

    NARCIS (Netherlands)

    Lingen, J.N.J. van

    2006-01-01

    Supported vanadium oxide catalysts are widely used in industry. However, the molecular structure of the active species, responsible for the actual catalysis, is for a large part still unknown. This thesis describes four years study on the elucidation of this molecular structure. It mainly focuses on

  13. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, Bartley B. [Univ. of California, Berkeley, CA (United States)

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF2, ThO2, YDT(0.85ThO2-0.15YO1.5), and LDT(0.85ThO2- 0.15LaO1.5) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  14. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF[sub 2], ThO[sub 2], YDT(0.85ThO[sub 2]-0.15YO[sub 1.5]), and LDT(0.85ThO[sub 2]- 0.15LaO[sub 1.5]) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  15. Extraction of vanadium from vanadium slag by high pressure oxidative acid leaching

    Science.gov (United States)

    Zhang, Guo-quan; Zhang, Ting-an; Lü, Guo-zhi; Zhang, Ying; Liu, Yan; Liu, Zhuo-lin

    2015-01-01

    To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy transformation, and the form of leach residues were made by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The result shows that the vanadium slag is composed of major phases of fayalite, titanomagnetite, and spinel. During the high pressure oxidative acid leaching process, the fayalite and spinel phases are gradually decomposed by sulfuric acid, causing the release of vanadium and iron in the solution. Meanwhile, unreacted silicon and titanium are enriched in the leach residues. With the initial concentration of sulfuric acid at 250 g·L-1, a leaching temperature of 140°C, a leaching time of 50 min, a liquid-solid ratio of 10:1 mL·g-1, and oxygen pressure at 0.2 MPa, the leaching rate of vanadium reaches 97.69%.

  16. Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Show, B.K., E-mail: bijay_show@rediffmail.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Veerababu, R., E-mail: veeru_met@yahoo.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Balamuralikrishnan, R., E-mail: bmk_pgh@yahoo.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Malakondaiah, G., E-mail: director@dmrl.drdo.in [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India)

    2010-03-15

    DMR-249A is a low carbon microalloyed high-strength low-alloy (HSLA) steel. While DMR-249A plates of thickness less than 18 mm meet the specified room temperature yield strength (390 MPa) and Charpy impact toughness (78J at -60 deg. C) in the as-rolled condition, thicker plates require water quenching and tempering. Elimination of the quenching and tempering treatment can result in significant cost and energy savings besides offering increased productivity. Therefore, in the present work, modifications to the base DMR-249A steel composition have been investigated with the objective of producing thicker gage plates (24 mm) capable of meeting the specified properties in the normalized condition. Plates from three modified compositions i.e., containing 0.015 wt.% titanium and 0.06, 0.09 and 0.12 wt.% vanadium respectively and one composition with 0.10 wt.% vanadium, and without any titanium were investigated over a range of normalizing temperatures (875-1000 deg. C). In all cases, only the steel without titanium met the specified properties in the normalized condition. Microstructural investigations using scanning and transmission electron microscopy, as well as support evidence from calculations performed using ThermoCalc software, suggest that this is due to the presence of nanoscale vanadium rich carbonitride particles distributed throughout the matrix. These particles were absent in the titanium-containing steel at a similar vanadium level.

  17. Recovery of Vanadium from a High Ca/V Ratio Vanadium Slag Using Sodium Roasting and Ammonia Leaching

    Science.gov (United States)

    Xu, Song; Long, Mujun; Chen, Dengfu; Fan, Helin; Chen, Yuting; Sun, Xue

    In order to seek an effective extraction process for vanadium, the recovery of vanadium from a high Ca/V ratio vanadium slag was studied by sodium roasting and ammonia leaching. In the present paper, the oxidation and leaching process of vanadium slag was investigated by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS) techniques. The effects of ammonium carbonate concentration, leaching temperature and leaching time on the leaching ratio of vanadium were discussed. As indicated in the experimental result, the optimal (NH4)2CO3 concentration was 120g/L, leaching temperature was 60°C and leaching time was 20 min. Approximately 92% of the vanadium was recovered under the optimal conditions. Furthermore, by means of X-ray diffraction analysis, the phase transformations of the vanadium slag during roasting and leaching processes were analyzed and discussed.

  18. Structure and properties of V90Co10 membrane alloy

    Science.gov (United States)

    Sipatov, Ivan; Pastukhov, Eduard; Fetisov, Andrey; Zvonarev, Sergey; Melchakov, Stanislav

    2017-09-01

    Alloys based on vanadium having bcc structure are considered as an alternative to palladium membrane alloys for hydrogen filtering. The membrane alloy (V90Co10) was studied by X-ray photoelectron spectroscopy, scanning electron and confocal microscopy. Gaseous impurities (oxygen, nitrogen, carbon, and hydrogen) in the membrane alloy was measured. The surface preparation method for the membrane alloy was developed, this makes possible to reduce roughness (Ra) down to 0.05 µm. It was established that in subsurface layer (˜10 nm) vanadium is in metallic form as well as 4+ and 2+ oxidation levels; while cobalt has only metallic form. Homogeneous distribution of elements in the bulk alloy was proved by chemical microanalysis. The value of hydrogen permeability of the V90Co10 membrane alloy was measured by non-stationary technique within the temperature and pressure ranges (623-723 K and 9-30 kPa, respectively). It was found that the hydrogen permeability of the V90Co10 membrane alloy is comparable with membranes made of metallic palladium.

  19. In vivo degradation behavior and biological activity of some new Mg–Ca alloys with concentration's gradient of Si for bone grafts

    Energy Technology Data Exchange (ETDEWEB)

    Trincă, Lucia Carmen, E-mail: lctrinca@uaiasi.ro [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, Str. Aleea M. Sadoveanu, No. 3, 700490 Iasi (Romania); Fântânariu, Mircea, E-mail: mfantanariu@uaiasi.ro [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Veterinary Medicine, Str. Aleea M. Sadoveanu, No. 8, 700489 Iasi (Romania); Solcan, Carmen, E-mail: csolcan@yahoo.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Veterinary Medicine, Str. Aleea M. Sadoveanu, No. 8, 700489 Iasi (Romania); Trofin, Alina Elena, E-mail: aetrofin@yahoo.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, Str. Aleea M. Sadoveanu, No. 3, 700490 Iasi (Romania); Burtan, Liviu, E-mail: lburtan@uaiasi.ro [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Veterinary Medicine, Str. Aleea M. Sadoveanu, No. 8, 700489 Iasi (Romania); Acatrinei, Dumitru Mihai, E-mail: dacatrinei@yahoo.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Veterinary Medicine, Str. Aleea M. Sadoveanu, No. 8, 700489 Iasi (Romania); Stanciu, Sergiu, E-mail: sergiustanciu2003@yahoo.com [“Gheorghe Asachi” Technical University, Faculty of Materials Science and Engineering, Str. Prof. D. Mangeron, No. 67, 700050 Iasi (Romania); and others

    2015-10-15

    Highlights: • A Mg–Ca alloy with Si concentration gradient was obtained as bone graft material. • Degradation rate of the Mg–Ca–Si alloy was investigated by SEM and EDAX techniques. • Subcutaneous and tibiae implants in rats were monitored by Biochemical, histological, RX and CT investigations monitored implant's evolution. • Si concentration gradient decreased the alloy degradation rate during bone healing. - Abstract: Magnesium based alloys, especially Mg–Ca alloys, are biocompatible substrates with mechanical properties similar to those of bones. The biodegradable alloys of Mg–Ca provide sufficient mechanical strength in load carrying applications as opposed to biopolymers and also they avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. The main issue facing a biodegradable Mg–Ca alloy is the fast degradation in the aggressive physiological environment of the body. The alloy's corrosion is proportional with the dissolution of the Mg in the body: the reaction with the water generates magnesium hydroxide and hydrogen. The accelerated corrosion will lead to early loss of the alloy's mechanical integrity. The degradation rate of an alloy can be improved mainly through tailoring the composition and by carrying out surface treatments. This research focuses on the ability to adjust degradation rate of Mg–Ca alloys by an original method and studies the biological activity of the resulted specimens. A new Mg–Ca alloy, with a Si gradient concentration from the surface to the interior of the material, was obtained. The surface morphology was investigated using scanning electron microscopy (VegaTescan LMH II, SE detector, 30 kV), X-ray diffraction (X’Pert equipment) and energy dispersive X-ray (Bruker EDS equipment). In vivo degradation behavior, biological compatibility and activity of Mg–Ca alloys with/without Si gradient concentration were studied with an implant model (subcutaneous

  20. Vanadium in marine mussels and algae.

    Science.gov (United States)

    Sperling, K R; Bahr, B; Ott, J

    2000-01-01

    A method is presented which is sensitive enough for the determination of vanadium (V) in marine organisms such as mussels and algae. It was sufficiently checked by a reference material and it was applied to V determination in blue mussels and brown algae from the German Bight.

  1. Structure and function of vanadium haloperoxidases

    NARCIS (Netherlands)

    Wever, R.; Michibata, H.

    2012-01-01

    Vanadium haloperoxidases contain the bare metal oxide vanadate as a prosthetic group and differ strongly from the heme peroxidases in substrate specificity and molecular properties. The substrates of these enzymes are limited to halides and sulfides, which in the presence of hydrogen peroxide are

  2. Lithium insertion in sputtered vanadium oxide film

    DEFF Research Database (Denmark)

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  3. Geochemistry of vanadium (V) in Chinese coals.

    Science.gov (United States)

    Liu, Yuan; Liu, Guijian; Qu, Qinyuan; Qi, Cuicui; Sun, Ruoyu; Liu, Houqi

    2017-10-01

    Vanadium in coals may have potential environmental and economic impacts. However, comprehensive knowledge of the geochemistry of V in coals is lacking. In this study, abundances, distribution and modes of occurrence of V are reviewed by compiling >2900 reported Chinese coal samples. With coal reserves in individual provinces as the weighting factors, V in Chinese coals is estimated to have an average abundance of 35.81 μg/g. Large variation of V concentration is observed in Chinese coals of different regions, coal-forming periods, and maturation ranks. According to the concentration coefficient of V in coals from individual provinces, three regions are divided across Chinese coal deposits. Vanadium in Chinese coals is probably influenced by sediment source and sedimentary environment, supplemented by late-stage hydrothermal fluids. Specifically, hydrothermal fluids have relatively more significant effect on the enrichment of V in local coal seams. Vanadium in coals is commonly associated with aluminosilicate minerals and organic matter, and the modes of V occurrence in coal depend on coal-forming environment and coal rank. The Chinese V emission inventory during coal combustion is estimated to be 4906 mt in 2014, accounting for 50.55 % of global emission. Vanadium emissions by electric power plants are the largest contributor.

  4. Temperature dependence of thermal conductivity of vanadium ...

    Indian Academy of Sciences (India)

    Unknown

    . Cryogenic Engineering .... Thermal conductivity of vanadium substituted BPSCCO system. 441 trical resistivity as well as the small decrease ..... G, Marre D, Putti M and Siri A S 1997 Physica C273 314. Chawlek J M, Uher C, Whitaker J F and ...

  5. Catalytic determination of vanadium in water

    Science.gov (United States)

    Fishman, M. J.; Skougstad, M.W.

    1964-01-01

    A rapid, accurate, and sensitive spectrophotometric method for the quantitative determination of trace amounts of vanadium in water is based on the catalytic effect of vanadium on the rate of oxidation of gallic acid by persulfate in acid solution. Under given conditions of concentrations of reactants, temperature, and reaction time, the extent of oxidation of gallic acid is proportional to the concentration of vanadium present. Vanadium is determined by measuring the absorbance of the sample at 415 m?? and comparison with standard solutions treated in an identical manner. Concentrations in the range of from 0.1 to 8.0 ??g. per liter may be determined with a standard deviation of 0.2 or less. By reducing the reaction time, the method may be extended to cover the range from 1 to 100 ??g. with a standard deviation of 0.8 or less. Several substances interfere, including chloride above 100 p.p.m., and bromide and iodide in much lower concentrations. Interference from the halides is eliminated or minimized by the addition of mercuric nitrate solution. Most other substances do not interfere at the concentration levels at which they commonly occur in natural waters.

  6. Role of vanadium in Bi-2223 ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 54; Issue 2. Role of vanadium in Bi-2223 ceramics. D R Mishra ... higher magnetization scattering at the Cu site. The results were explained keeping in mind the liquid phase mechanism behind the formation of the 2223 phase and the possibility of magnetic scattering.

  7. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Directory of Open Access Journals (Sweden)

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  8. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  9. Grain boundary migration induced segregation in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Ohnuki, S.; Takahashi, H. [Univ. of Hokkaido (Japan)

    1996-10-01

    Analytical electron microscopy results are reported for a series of vanadium alloys irradiated in the HFIR JP23 experiment at 500{degrees}C. Alloys were V-5Cr-5Ti and pure vanadium which are expected to have transmuted to V-15Cr-5Ti and V-10Cr following irradiation. Analytical microscopy confirmed the expected transmutation occurred and showed redistribution of Cr and Ti resulting from grain boundary migration in V-5Cr-5Ti, but in pure V, segregation was reduced and no clear trends as a function of position near a boundary were identified.

  10. Oxygen Activity in Melts of Fe-C-Cr-Ni Based Alloys

    Directory of Open Access Journals (Sweden)

    Záděra A.

    2016-12-01

    Full Text Available Oxygen is an element that is first purposely brought into the steel melt to remove some unwanted elements or to reduce their concentration (oxidation. In the made cast steel there is on the contrary necessary to reduce the oxygen content with the use of deoxidation to such a level in order to avoid a reaction with carbon with the formation of CO bubbles. Concentration of oxygen in steel before casting is given, in particular, by the manner of metallurgical processing and the used deoxidation process. Oxygen is found in molten steels both as chemically bound in the form of oxides and in the form of oxygen dissolved in the solution – the melt. Chemical composition of the melt strongly influences the activity of oxygen dissolved in the melt and further on the composition of oxidic inclusions forming in the melt during the reaction with oxygen. In the Fe-C-Cr-Ni based alloys in the reaction with oxygen greatly participates also chrome, whose products are often in solid state and they are the cause of forming such defects as e.g. oxidic films.

  11. Comparison of Microstructural and Tribological Effects of Low Vanadium-Low Titanium Additions to a Gray Cast Iron

    Science.gov (United States)

    Hassani, A.; Habibolahzadeh, A.; Sadeghinejad, S.

    2013-01-01

    Effects of low amounts of vanadium and titanium additions on the microstructure, tribological properties of a gray cast iron were studied and an overall comparison was made between these two alloys. Pin-on-disk tests were performed on the specimens at three different loads and two sliding speeds. SEM was utilized to study the worn surfaces and the mechanisms under which wear occurred. Local chemical analyses were conducted on the specific spots in the wear tracks by EDX. Wear mechanisms were determined and the quantitative amounts of the elements in the tribochemical films formed on the wear tracks were evaluated. Both vanadium-treated and untreated samples exhibited oxidative wear mechanism under mild regimes and adhesive wear mechanism under severe wear regime. The wear rate was reduced up to 85% when the vanadium-treated sample was tested; it showed the best wear resistance. The alloy having titanium, however, showed the least wear resistance compared to the others. It could be due to the formation of type-D graphite in its microstructure.

  12. Static recrystallisation of steels produced by direct strip casting – The effect of carbon and vanadium concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ramajayam, M. [Institute for Frontier Materials, Deakin University, 3216 (Australia); Stanford, N. [Department of Materials Science and Engineering, Monash University, 3800 (Australia)

    2016-08-01

    Six steel alloys containing a range of carbon and vanadium concentrations have been prepared by simulated strip casting. The alloys were cold rolled and annealed to examine the recrystallisation behaviour. The annealing treatment resulted in three processes occurring concurrently: recrystallisation; spheroidisation of cementite, and precipitation of vanadium-enriched nano-precipitates. These nano-precipitates had a much higher concentration of Fe than would be expected from traditional processing methods, and this increased their maximum attainable volume fraction. In the two alloys that did not contain second phase particles, recrystallisation showed typical reaction kinetics, and the recrystallised grain size continued to increase with increasing time at temperature. However, in those alloys with second phase particles the recrystallised grains showed unusual behaviour, rapidly reaching an upper limit to their size. Continued time at temperature was not accompanied by an increase in the grain size. This growth limit has been attributed to Zener pinning, with the limiting grain size being proportional to the Zener pinning pressure. It has been proposed that the delayed recrystallisation that is typically observed in strip cast steels is likely to be the result of nano-scale precipitation which is unique to rapidly cooled materials, such as those produced by strip casting.

  13. Thermally activated low temperature creep and primary water stress corrosion cracking of NiCrFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hall, M.M. Jr.

    1993-10-01

    A phenomenological SCC-CGR model is developed based on an apriori assumption that the SCC-CGR is controlled by low temperature creep (LTC). This mode of low temperature time dependent deformation occurs at stress levels above the athermal flow stress by a dislocation glide mechanism that is thermally activated and may be environmentally assisted. The SCC-CGR model equations developed contain thermal activation parameters descriptive of the dislocation creep mechanism. Thermal activation parameters are obtained by fitting the CGR model to SCC-CGR data obtained on Alloy 600 and Alloy X-750. These SCC-CGR activation parameters are compared to LTC activation parameters obtained from stress relaxation tests. When the high concentration of hydrogen at the tip of an SCC crack is considered, the SCC-CGR activation energies and rate sensitivities are shown to be quantitatively consistent with hydrogen reducing the activation energy and increasing the strain rate sensitivity in LTC stress relaxation tests. Stress dependence of SCC-CGR activation energy consistent with that found for the LTC activation energy. Comparisons between temperature dependence of the SCC-CGR stress sensitivity and LTC stress sensitivity provide a basis for speculation on effects of hydrogen and solute carbon on SCC crack growth rates.

  14. Biological effects of activation products and other chemicals released from fusion power plants

    Energy Technology Data Exchange (ETDEWEB)

    Strand, J.A.; Poston, T.M.

    1976-09-01

    Literature reviews indicate that existing information is incomplete, often contradictory, and of questionable value for the prediction and assessment of ultimate impact from fusion-associated activation products and other chemical releases. It is still uncertain which structural materials will be used in the blanket and first wall of fusion power plants. However, niobium, vanadium, vanadium-chromium alloy, vanadium-titanium alloy, sintered aluminum product, and stainless steel have been suggested. The activation products of principal concern will be the longer-lived isotopes of /sup 26/Al, /sup 49/V, /sup 51/Cr, /sup 54/Mn, /sup 55/Fe, /sup 58/Co, /sup 60/Co, /sup 93/Nb, and /sup 94/Nb. Lithium released to the environment either during the mining cycle, from power plant operation or accident, may be in the form of a number of compound types varying in solubility and affinity for biological organisms. The effects of a severe liquid metal fire or explosion involving Na or K will vary according to inherent abiotic and biotic features of the affected site. Saline, saline-alkaline, and sodic soils of arid lands would be particularly susceptible to alkaline stress. Beryllium released to the environment during the mining cycle or reactor accident situation could be in the form of a number of compound types. Adverse effects to aquatic species from routine chemical releases (biocides, corrosion inhibitors, dissolution products) may occur in the discharge of both fission and fusion power plant designs.

  15. Antimicrobial Activity of Copper Alloys Against Invasive Multidrug-Resistant Nosocomial Pathogens.

    Science.gov (United States)

    Eser, Ozgen Koseoglu; Ergin, Alper; Hascelik, Gulsen

    2015-08-01

    The emergence and spread of antibiotic resistance demanded novel approaches for the prevention of nosocomial infections, and metallic copper surfaces have been suggested as an alternative for the control of multidrug-resistant (MDR) bacteria in surfaces in the hospital environment. This study aimed to evaluate the antimicrobial activity of copper material for invasive MDR nosocomial pathogens isolated over time, in comparison to stainless steel. Clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) (n:4), OXA-23 and OXA-58 positive, MDR Acinetobacter baumannii (n:6) and Pseudomonas aeruginosa (n:4) were evaluated. The antimicrobial activity of coupons containing 99 % copper and a brass alloy containing 63 % copper was assessed against stainless steel. All the materials demonstrated statistically significant differences within each other for the logarithmic reduction of microorganisms. Among the three materials, the highest reduction of microorganisms was seen in 99 % copper and the least in stainless steel. The result was statistically significant especially for 0, 2, and 4 h (P = 0.05). 99 % copper showed a bactericidal effect at less than 1 h for MRSA and at 2 h for P. aeruginosa. 63 % copper showed a bactericidal effect at 24 h for P. aeruginosa strains only. Stainless steel surfaces exhibited a bacteriostatic effect after 6 h for P. aeruginosa strains only. 99 % copper reduced the number of bacteria used significantly, produced a bactericidal effect and was more effective than 63 % copper. The use of metallic copper material could aid in reducing the concentration of bacteria, especially for invasive nosocomial pathogens on hard surfaces in the hospital environment.

  16. Protective effect of alpha glucosyl hesperidin (G-hesperidin) on chronic vanadium induced testicular toxicity and sperm nuclear DNA damage in male Sprague Dawley rats.

    Science.gov (United States)

    Vijaya Bharathi, B; Jaya Prakash, G; Krishna, K M; Ravi Krishna, C H; Sivanarayana, T; Madan, K; Rama Raju, G A; Annapurna, A

    2015-06-01

    The study was conducted to evaluate the vanadium-induced testicular toxicity and its effect on sperm parameters, sperm nuclear DNA damage and histological alterations in Sprague Dawley rats and to assess the protective effect of G-hesperidin against this damage. Treatment of rats with vanadium at a dose of 1 mg kg bw(-1) for 90 days resulted in significant reduction in serum testosterone levels, sperm count and motility. Further, a parallel increase in abnormal sperm morphology and adverse histopathological changes in testis was also associated with vanadium administration when compared to normal control. Moreover, sperm chromatin dispersion assay revealed that vanadium induces sperm nuclear DNA fragmentation. A marked increase in testicular malondialdehyde levels and decreased activity of antioxidant enzymes such as superoxide dismutase and catalase indicates vanadium-induced oxidative stress. Co-administration of G-hesperidin at a dose of 25 and 50 mg kg bw(-1) significantly attenuated the sperm parameters and histological changes by restoring the antioxidant levels in rat testis. These results suggested that vanadium exposure caused reduced bioavailability of androgens to the tissue and increased free radical formation, thereby causing structural and functional changes in spermatozoa. G-hesperidin exhibited antioxidant effect by protecting the rat testis against vanadium-induced oxidative damage, further ensures antioxidant potential of bioflavonoids. © 2014 Blackwell Verlag GmbH.

  17. Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

    Directory of Open Access Journals (Sweden)

    Zhenlei Cai

    2016-03-01

    Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

  18. Recovery of motor coordination after exercise is correlated to enhancement of brain-derived neurotrophic factor in lactational vanadium-exposed rats.

    Science.gov (United States)

    Wang, Dean-Chuan; Lin, Yu-Yi; Lin, Hwai-Ting

    2015-07-23

    Lactational exposure to vanadium can reduce the locomotor activity in adult animals. In this study, we investigated whether lactational vanadium exposure impairs the motor coordination and whether exercise ameliorates this dysfunction. Sprague-Dawley dams were treated with or without vanadium during lactation. The weaned male offspring were trained to treadmill running for 5 weeks and then examined their motor coordination on a rotarod. The neuroprotective effect of exercise was evaluated by the brain-derived neurotrophic factor (BDNF) in plasma and cerebellum. The results demonstrated that vanadium-exposed rats exhibited impaired motor coordination and reduced plasma and cerebellar BDNF levels. Treadmill running during childhood-adolescence prevented the impaired motor coordination in the lactational vanadium-exposed rats. The beneficial effect of treadmill running on motor coordination in the vanadium-exposed rats was correlated to the normalization of plasma and cerebellar BDNF levels, as well as the increased TrkB phosphorylation in the cerebellum. The result suggests that exercise may prevent the impairment of motor coordination in the lactational vanadium-exposed rats. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  19. Hot-deformation behaviour of α+β Ti-Al-V-Fe experimental alloys

    Science.gov (United States)

    Prozesky, Dawid J.; Bodunrin, Michael O.; Chown, Lesley H.

    2017-10-01

    To reduce the cost of metallic alloys the first approach considered is to substitute expensive alloying elements with inexpensive elements that fulfil similar functions. The second approach is to optimise the microstructure and mechanical properties of the alloys by adjusting processing conditions. Iron, a cheap β-stabilising element in titanium alloys, was added to partially substitute vanadium in experimental Ti-6Al-xV-yFe alloys (where x = 1-4, y = 0-3 and x+y = 4). Unlike other studies where vanadium was totally replaced by iron, in this work partial substitution of V by 1-3 wt % Fe was made to limit the possibility of forming intermetallic phases in the alloys. The experimental alloys were produced by vacuum arc melting and the small ingots were machined to produce plane strain compression samples for hot isothermal testing on a Gleeble 3500. The tests were done at a temperature of 900°C, strain rate of 1s-1 and total strains of 0.6 and 1.2, under plane strain conditions. The microstructures of the as-cast and deformed samples were analysed using optical and scanning electron microscopy (SEM) to assess the deformation mechanisms. The flow stress curves showed that the as-cast Ti-6Al-4V had a higher resistance to deformation than the iron-added experimental alloys. The amount of total strain had a significant effect on the flow behaviour of the alloys. Microscopy showed that deformation bands were more prominent in the deformed Ti-6Al-4V alloy than in the deformed Ti-Al-V-Fe alloys. SEM images revealed rotation and bending of α-laths in the deformed experimental Ti-Al-V-Fe alloys. The low resistance to deformation observed in the experimental alloys at 900°C was sensitive to the higher ratio of iron to vanadium.

  20. Fe3+-Doped TiO2 Nanotube Arrays on Ti-Fe Alloys for Enhanced Photoelectrocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Jiangdong Yu

    2016-06-01

    Full Text Available Highly ordered, vertically oriented Fe3+-doped TiO2 nanotube arrays (Fe-TNTs were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS and related electrochemical techniques. XPS results demonstrated that Fe3+ ions were successfully doped into TiO2 nanotubes. The photoelectrochemical activity of Fe-TNTs was compared with that of pure TiO2 nanotube arrays (TNTs. The results showed that Fe-TNTs grown on low concentration (0.5 wt %–1 wt % Fe Ti-Fe alloys possessed higher photocurrent density than TNTs. The Fe-TNTs grown on Ti-Fe alloy containing 0.8 wt % Fe exhibited the highest photoelectrochemical activity and the photoelectrocatalytic degradation rate of methylene blue (MB aqueous solution was significantly higher than that of TNTs.

  1. Facile Fabrication of Platinum-Cobalt Alloy Nanoparticles with Enhanced Electrocatalytic Activity for a Methanol Oxidation Reaction

    Science.gov (United States)

    Huang, Huihong; Hu, Xiulan; Zhang, Jianbo; Su, Nan; Cheng, Jiexu

    2017-03-01

    Decreasing the cost associated with platinum-based catalysts along with improving their catalytic properties is a major challenge for commercial direct methanol fuel cells. In this work, a simple and facile strategy was developed for the more efficient preparation of multi-walled carbon nanotube (MWCNT) -supported Pt/CoPt composite nanoparticles (NPs) via solution plasma sputtering with subsequent thermal annealing. Quite different from general wet synthesis methods, Pt/CoPt composite NPs were directly derived from metal wire electrodes without any additions. The obtained Pt/CoPt/MWCNTs composite catalysts exhibited tremendous improvement in the electro-oxidation of methanol in acidic media with mass activities of 1719 mA mg-1Pt. This value is much higher than that of previous reports of Pt-Co alloy and commercial Pt/C (3.16 times) because of the many active sites and clean surface of the catalysts. The catalysts showed good stability due to the special synergistic effects of the CoPt alloy. Pt/CoPt/MWCNTs can be used as a promising catalyst for direct methanol fuel cells. In addition, this solution plasma sputtering-assisted synthesis method introduces a general and feasible route for the synthesis of binary alloys.

  2. Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag

    Energy Technology Data Exchange (ETDEWEB)

    Chartier, D., E-mail: david.chartier@cea.fr [Commissariat à l' Energie Atomique et aux Energies Alternatives, CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze (France); Muzeau, B. [DEN-Service d’Etude du Comportement des Radionucléides (SECR), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Stefan, L. [AREVA NC/D& S - France/Technical Department, 1 place Jean Millier 92084 Paris La Défense (France); Sanchez-Canet, J. [Commissariat à l' Energie Atomique et aux Energies Alternatives, CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze (France); Monguillon, C. [DEN-Service d’Etude du Comportement des Radionucléides (SECR), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France)

    2017-03-15

    Highlights: • Embedded in cement, magnesium is corroded by residual water present in porosity of the matrix. • Corrosion is enhanced by galvanic phenomenon when magnesium is in contact with graphite. • Galvanic corrosion of magnesium in contact with graphite debris is shown to be severe with ordinary Portland cement. • Galvanic corrosion is significantly lowered in high alkali medium such as sodium hydroxide. • Sodium hydroxide activated blast furnace slag is a convenient binder to embed magnesium. - Abstract: Magnesium alloys and graphite from spent nuclear fuel have been stored together in La Hague plant. The packaging of these wastes is under consideration. These wastes could be mixed in a grout composed of industrially available cement (Portland, calcium aluminate…). Within the alkaline pore solution of these matrixes, magnesium alloys are imperfectly protected by a layer of Brucite resulting in a slow corrosion releasing hydrogen. As the production of this gas must be considered for the storage safety, and the quality of wasteform, it is important to select a cement matrix capable of lowering the corrosion kinetics. Many types of calcium based cements have been tested and most of them have caused strong hydrogen production when magnesium alloys and graphite are conditioned together because of galvanic corrosion. Exceptions are binders based on alkali hydroxide activated ground granulated blast furnace slag (BFS) which are presented in this article.

  3. Speciation of vanadium in Chinese cabbage (Brassica rapa L.) and soils in response to different levels of vanadium in soils and cabbage growth.

    Science.gov (United States)

    Tian, Liyan; Yang, Jinyan; Alewell, Christine; Huang, Jen-How

    2014-09-01

    This study highlights the accumulation and speciation of vanadium in Chinese cabbage (Brassica rapa L.) in relation to the speciation of soil vanadium with pot experiments at 122-622mgVkg(-1) by spiking NH4VO3. Cabbage planting decreased the bioavailable and residual vanadium based on sequential extraction, leading to enrichment of oxalate-extractable vanadium in soils. The biomass production increased with increasing concentrations of soil vanadium from 122 to 372mgVkg(-1), probably due to the increasing nitrogen availability and low vanadium availability in our soils with a consequent low vanadium toxicity. Although the concentrations of root vanadium (14.4-24.9mgVkg(-1)) related positively with soil vanadium, the bio-dilution alleviated the increase of leaf vanadium (2.1-2.7mgVkg(-1)). The predominance of vanadium(IV) in leaves (∼60-80% of total vanadium) indicates bio-reduction of vanadium in Chinese cabbage, since the mobile vanadium in oxic soils was usually pentavalent. Approximately 15-20% of the leaf vanadium was associated with recalcitrant leaf tissues. The majority of leaf vanadium was water and ethanol extractable, which is considered mobile and may cause more toxic effects on Chinese cabbage. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

    OpenAIRE

    Qiushi Zheng; Yimin Zhang; Tao Liu; Jing Huang; Nannan Xue; Qihua Shi

    2017-01-01

    Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extraction of vanadium. Hence, the vanadium location is necessary for exploring the essence of vanadium extraction. Although most infer that vanadium may substitute for trivalent aluminium (Al) as the isomorphism in muscovite for the similar atomic rad...

  5. Vanadium Oxidation State Determination by X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Duchesne, Marc A.; Nakano, Jinichiro; Hu, Yongfeng; MacLennan, Aimee; Hughes, Robin W.; Bennett, James; Nakano, Anna

    Vanadium is found in slags produced during metal refinement and fossil fuel combustion/gasification. The oxidation state of vanadium in slag has technological and environmental implications. For example, it may affect slag flow and refractory wear inside reactors, as well as leachability and toxicity of industrial by-products. Determination of vanadium's oxidation state in crystalline phases can be achieved via the widely adopted X-ray diffraction (XRD) technique. However, this technique does not provide information on vanadium in amorphous phases. The objective of this research is to determine the oxidation state of vanadium in petroleum coke gasification samples and laboratory samples using X-ray absorption spectroscopy (XAS) with Canadian Light Source's soft X-ray micro-characterization beamline (SXRMB). Linear combination fitting of XAS spectra with reference samples allowed quantitative determination of vanadium speciation.

  6. Surface Oxide Net Charge of a Titanium Alloy ; Modulation of Fibronectin-Activated Attachment and Spreading of Osteogenic Cells

    Science.gov (United States)

    Rapuano, Bruce E.; MacDonald, Daniel E.

    2010-01-01

    In the current study, we have altered the surface oxide properties of a Ti6Al4V alloy using heat treatment or radiofrequency glow discharge (RFGD) in order to evaluate the relationship between the physico-chemical and biological properties of the alloy's surface oxide. The effects of surface pretreatments on the attachment of cells from two osteogenic cell lines (MG63 and MC3T3) and a mesenchymal stem cell line (C3H10T1/2) to fibronectin adsorbed to the alloy were measured. Both heat and RFGD pretreatments produced a several-fold increase in the number of cells that attached to fibronectin adsorbed to the alloy (0.001 and 10 nM FN) for each cell line tested. An antibody (HFN7.1) directed against the central integrin binding domain of fibronectin produced a 65-70% inhibition of cell attachment to fibronectin-coated disks, incdicating that cell attachment to the metal discs was dependent on fibronectin binding to cell integrin receptors. Both treatments also accelerated the cell spreading response manifested by extensive flattening and an increase in mean cellular area. The treatment-induced increases in the cell attachment activity of adsorbed fibronectin were correlated with previously demonstrated increases in Ti6Al4V oxide negative net surface charge at physiological pH produced by both heat and RFGD pretreatments. Since neither treatment increased the adsorption mass of fibronectin, these findings suggest that negatively charged surface oxide functional groups in Ti6Al4V can modulate fibronectin's integrin receptor activity by altering the adsorbed protein's conformation. Our results further suggest that negatively charged functional groups in the surface oxide can play a prominent role in the osseointegration of metallic implant materials. PMID:20884181

  7. Extraction of Vanadium from Vanadium Slag Via Non-salt Roasting and Ammonium Oxalate Leaching

    Science.gov (United States)

    Li, Meng; Du, Hao; Zheng, Shili; Wang, Shaona; Zhang, Yang; Liu, Biao; Dreisinger, David Bruce; Zhang, Yi

    2017-10-01

    A clean method featuring non-salt roasting followed by (NH4)2C2O4 leaching to recover vanadium from vanadium slag was proposed. The carcinogenic Cr6+ compounds and exhaust gases were avoided, and the water generated from vanadate precipitation may be recycled and reused in this new leaching process. The leaching residues may be easily used by a blast furnace. Moreover, (NH4)2C2O4 solution was used as a leaching medium to avoid expensive and complicated ammonium controlling operations as a result of the stability of (NH4)2C2O4 at a high temperature. The transformation mechanisms of vanadium- and chromium-bearing phases were systematically investigated by x-ray diffraction analysis and scanning electron microscopy with energy-disperse x-ray spectrometry, respectively. In addition, the effects of oxygen concentration, roasting temperature, and holding time on vanadium recovery were investigated. Finally, the effects of leaching variables on the vanadium leaching rate were also examined.

  8. Discrepancy between theory and measurement of superconducting vanadium

    Science.gov (United States)

    Zheng, X. H.; Walmsley, D. G.

    2015-08-01

    We have extracted consistent phonon dispersion information out of rather inconsistent vanadium X-ray scattering data from synchrotron and vacuum tube sources. With this and a new theoretical approach we have made firm predictions for the tunnelling conductance of superconducting vanadium; it is in unusually poor agreement with experimentally measured values. We argue that the problem lies in the experimental measurement rather than the theory. The preparation of a suitable high quality tunnel barrier on vanadium represents an outstanding challenge.

  9. Modified lithium vanadium oxide electrode materials products and methods

    Science.gov (United States)

    Thackeray, Michael M.; Kahaian, Arthur J.; Visser, Donald R.; Dees, Dennis W.; Benedek, Roy

    1999-12-21

    A method of improving certain vanadium oxide formulations is presented. The method concerns fluorine doping formulations having a nominal formula of LiV.sub.3 O.sub.8. Preferred average formulations are provided wherein the average oxidation state of the vanadium is at least 4.6. Herein preferred fluorine doped vanadium oxide materials, electrodes using such materials, and batteries including at least one electrode therein comprising such materials are provided.

  10. A Contemporary Treatment Approach to Both Diabetes and Depression by Cordyceps sinensis, Rich in Vanadium

    Directory of Open Access Journals (Sweden)

    Jian-You Guo

    2010-01-01

    Full Text Available Diabetes mellitus is accompanied by hormonal and neurochemical changes that can be associated with anxiety and depression. Both diabetes and depression negatively interact, in that depression leads to poor metabolic control and hyperglycemia exacerbates depression. We hypothesize one novel vanadium complex of vanadium-enriched Cordyceps sinensis (VECS, which is beneficial in preventing depression in diabetes, and influences the long-term course of glycemic control. Vanadium compounds have the ability to imitate the action of insulin, and this mimicry may have further favorable effects on the level of treatment satisfaction and mood. C. sinensis has an antidepressant-like activity, and attenuates the diabetes-induced increase in blood glucose concentrations. We suggest that the VECS may be a potential strategy for contemporary treatment of depression and diabetes through the co-effect of C. sinensis and vanadium. The validity of the hypothesis can most simply be tested by examining blood glucose levels, and swimming and climbing behavior in streptozotocin-induced hyperglycemic rats.

  11. High activity of Pt(4)Mo alloy for the electrochemical oxidation of formic acid.

    Science.gov (United States)

    Gojković, Snezana Lj; Tripković, Amalija V; Stevanović, Rade M; Krstajić, Nedeljko V

    2007-12-04

    Surface processes on Pt4Mo alloy well-defined by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were studied in acid solution by cyclic voltammetry. It was established that Mo in the alloy is much more resistant toward electrochemical dissolution than pure Mo. During the potential cycling of Pt4Mo surfaces in completely quiescent electrolyte, hydrous Mo-oxide could be generated on Mo sites. Investigation of the formic acid oxidation revealed that this type of Mo-oxide enhances the reaction rate by more than 1 order of magnitude with respect to pure Pt. Surface poisoning by CO(ads) is significantly lower on Pt4Mo alloy than on pure Pt. The effect of hydrous Mo-oxide on the HCOOH oxidation rate was explained through the facilitated removal of the poisoning species and through its possible influence on the intrinsic rate of the direct reaction path.

  12. Efficient Extraction of Vanadium from Vanadium–Titanium Magnetite Concentrate by Potassium Salt Roasting Additives

    Directory of Open Access Journals (Sweden)

    Renmin Li

    2018-01-01

    Full Text Available In this paper, potassium salt roasting additives were applied to extract vanadium from vanadium–titanium magnetite concentrate. Meanwhile, the mechanisms of potassium salt roasting and acid leaching kinetics were investigated. The results indicate that potassium salt roasting additives are more efficient than sodium and calcium salt and that K2SO4 works best. Under certain conditions (a dosage of K2SO4 of 4 wt %, a roasting temperature of 900 °C, a roasting time of 1 h, a leaching temperature of 95 °C, a sulfuric acid concentration of 10% (v/v, and a leaching time of 1.5 h with a liquid to solid ratio of 3 mL/g the vanadium leaching efficiency reached 71.37%, an increase of 30.20% compared to that of blank roasting. Additionally, XRD and related SEM-EDS analyses indicated that K2SO4 fully destroyed the structure of vanadium-bearing minerals such as magnetite, and promoted the generation of soluble KVO3 to inhibit the formation of insoluble Ca(VO32 in the roasting process. Furthermore, it promoted the dissolution of sphene and the release of its vanadium in the leaching process, which increased the vanadium leaching efficiency significantly. Meanwhile, leaching kinetics analyses showed that the leaching process was controlled by internal diffusion; the apparent activation energy decreased from 37.43 kJ/mol with blank roasting to 26.31 kJ/mol with potassium salt roasting. The reaction order, with regards to the sulfuric acid concentration, decreased from 0.6588 to 0.5799. Therefore, potassium salt roasting could improve mineral activity, accelerating the leaching process and reducing the dependence on high temperature and high acidity.

  13. XAS study of vanadium in fluid cracking catalysts

    Science.gov (United States)

    Woolery, G. L.; Chin, A. A.; Kirker, G. W.; Huss, A.

    1989-06-01

    X-ray absorption spectroscopy was used to investigate the oxidation state and local environment of vanadium in Fluid Catalytic Cracking (FCC) catalysts as a function of processing and deactivation conditions. Our results suggest that oxidation of vanadium to V+5 alone is not solely responsible for catalyst deactivation but that other factors such as vanadium location and mobility play a significant role in catalyst performance. Basic alkaline earth oxide passivators such as MgO were found to interact strongly with vanadium during the regeneration period leading to formation of a magnesium vanadate compound.

  14. Chemical speciation of vanadium in coal bottom Ash

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Firat; Aydin, Isil; Hamamci, Candan [Science Faculty, Chemistry Department, Dicle University, Diyarbakir (Turkey); Saydut, Abdurrahman [Engineering Faculty, Mining Engineering Department, Dicle University, Diyarbakir (Turkey); Gunduz, Beniz [Science Faculty, Chemistry Department, Selcuk University, Konya (Turkey)

    2012-04-15

    Chemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two-stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Speciation of vanadium was carried out using a seven-step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701 mg kg{sup -1} d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196 mg kg{sup -1} d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176 mg kg{sup -1} d.w.) > sulfide (176 mg kg{sup -1} d.w.) > carbonate (85 mg kg{sup -1} d.w.) > oxidizable (50 mg kg{sup -1} d.w.) > water soluble (10.6 mg kg{sup -1} d.w.) > exchangeable (9.0 mg kg{sup -1} d.w.). (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Vanadium in fuel oil - a new solution

    Energy Technology Data Exchange (ETDEWEB)

    Czech, N. [Siemens, Muelheim (Germany); Finckh, H. [Siemens, Erlangen (Germany)

    1998-11-01

    Hot corrosion of the hot-gas-path components due to vanadium contamination is one of the hazards associated with heavy residual oil combustion in heavy-duty gas turbines. This economically attractive oil combustion process has benefited from the recently developed vanadium inhibition technique, which is currently being tested at the Valladolid 220 MWe combined cycle plant in Mexico. The method uses atomization of a dilute aqueous solution of Epsom salt (MgSO{sub 7},7H{sub 2}O) into very small droplets which are then injected onto the flame where intensive mixing takes place. The successful use of this new technique promises extended operating periods between cleanup operations, and cost reductions from the use of inexpensive materials, as well as the ability to operate advanced gas turbines on difficult fuels, not previously feasible. (UK)

  16. Hybrid LCA of a design for disassembly technology: active disassembling fasteners of hydrogen storage alloys for home appliances.

    Science.gov (United States)

    Nakamura, Shinichiro; Yamasue, Eiji

    2010-06-15

    In the current recycling system of end-of-life (EoL) appliances, which is based on shredding, alloying elements tend to end up in the scrap of base metals. The uncontrolled mixing of alloying elements contaminates secondary metals and calls for dilution with primary metals. Active disassembling fastener (ADF) is a design for disassembly (DfD) technology that is expected to solve this problem by significantly reducing the extent of mixing. This paper deals with a life cycle assessment (LCA) based on the waste input-output (WIO) model of an ADF developed using hydrogen storage alloys. Special attention is paid to the issue of dilution of mixed iron scrap using pig iron in an electric arc furnace (EAF). The results for Japanese electrical and electronic appliances indicate superiority of the recycling system based on the ADF over the current system in terms of reduced emissions of CO(2). The superiority of ADF was found to increase with an increase in the requirement for dilution of scrap.

  17. Antibacterial activity of Ag-Au alloy NPs and chemical sensor property of Au NPs synthesized by dextran.

    Science.gov (United States)

    Bankura, Kalipada; Maity, Dipanwita; Mollick, Md Masud Rahaman; Mondal, Dibyendu; Bhowmick, Biplab; Roy, Indranil; Midya, Tarapada; Sarkar, Joy; Rana, Dipak; Acharya, Krishnendu; Chattopadhyay, Dipankar

    2014-07-17

    Gold and silver-gold alloy nanoparticles with mean diameter of 10nm and narrow size distribution were prepared by reduction of the correspondent metal precursors using aqueous dextran solution which acts as both a reducing and capping agent. The formation of nanoparticles was characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and dynamic light scattering (DLS). The silver and gold nanoparticles exhibited absorption maxima at 425 and 551 nm respectively; while for the bimetallic Ag-Au alloy appeared 520 nm in between them. TEM images showed monodispersed particles in the range of 8-10nm. The crystallinity of the nanoparticles was assured by XRD analysis. DLS data gave particle size distribution. The dextran stabilized Au nanoparticles used as a colorimetric sensor for detection and estimation of pesticide present in water. The dextran stabilized Ag-Au alloy nanoparticles exhibited interesting antimicrobial activity against bacteria at micromolar concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. APPLICATION OF MODIFYING ALLOYING ALLOY CONTAINING NANOSIZED POWDERS OF ACTIVE ELEMENTS IN PRODUCTION OF HIGH-STRENGTH CAST IRON WITH GLOBULAR GRAPHITE

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2015-01-01

    Full Text Available Scientific and practical interest is the application of alloying alloy-modifiers for secondary treatment of high-strength cast iron to stabilize the process of spheroidization graphite and achieving higher physical-mechanical properties of castings. The peculiarity of the high-strength cast irons manufacturing technology is their tendency to supercooling during solidification in the mold. This leads to the formation of shrinkage defects and structurally free cementite, especially in thin-walled sections of the finished castings. To minimize these effects in foundry practice during production of ductile iron the secondary inoculation is widely used. In this regard, the question of the choice of the additives with effective impact not only on the graphitization process but also on the formation of the metallic base of ductile iron is relevant. The aim of the present work is to study the peculiarities of structure formation in cast iron with nodular graphite when alloying alloy-modifier based on tin with additions of nanoparticles of titanium carbide, yttrium oxide and graphite nano-pipes is used for secondary treatment. Melting of iron in laboratory conditions was performed in crucible induction furnace IST-006 with an acid lining held. Spheroidizing treatment of melt was realized with magnesium containing alloying alloy FeSiMg7 by means of ladle method. Secondary treatment of high strength cast iron was carried out by addition of alloying alloy-modifier in an amount of 0.1% to the bottom of the pouring ladle. Cast samples for chemical composition analysis, study of microstructure, technological and mechanical properties of the resultant alloy were made. Studies have shown that the secondary treatment of high strength cast iron with developed modifier-alloying alloy results in formation of the perlite metallic base due to the tin impact and nodular graphite with regular shape under the influence of titanium carbide, yttrium oxide and graphite nano

  19. Microadditions of boron and vanadium in ADI

    OpenAIRE

    Rzychoń T.; Kiełbus A.; Szala J.

    2007-01-01

    In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI). Melts were conducted ...

  20. Controlled synthesis and electrochemical properties of vanadium ...

    Indian Academy of Sciences (India)

    Vanadium oxides (V3O7.H2O and VO2) with different morphologies have been selectively synthesized by a facile hydrothermal approach using glucose as the reducing and structure-directing reagent. The as-obtained V3O7.H2O nanobelts have a length up to several tens of micrometers, width of about 60–150 nm and ...

  1. Determination of Leachable Vanadium (V) in Sediment

    African Journals Online (AJOL)

    NICO

    USA) were used for the filtration of sample solutions. RESEARCH ... were transferred to a Teflon beaker and treated on a hot plate at about 110 °C ... Table 1 Thermal programme for the determination of vanadium using. ET-AAS. Step. Temperature/°C. Ramp/s–1. Hold/s–1. Internal gas flow/mL min–1. 1. 120. 1. 10. 250. 2.

  2. Characterization of vanadium flow battery. Revised

    Energy Technology Data Exchange (ETDEWEB)

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2011-02-15

    This report summarizes the work done at Risoe-DTU testing a vanadium flow battery as part of the project ''Characterisation of Vanadium Batteries'' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The efficiency was not influenced by the cycling of the battery. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. The battery was operated together with a 11kW stall-regulated Gaia wind turbine to smooth the output of the wind turbine and during the tests the battery proved capable of firming the output of the wind turbine. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  3. Vanadium proton exchange membrane water electrolyser

    Science.gov (United States)

    Noack, Jens; Roznyatovskaya, Nataliya; Pinkwart, Karsten; Tübke, Jens

    2017-05-01

    In order to reverse the reactions of vanadium oxygen fuel cells and to regenerate vanadium redox flow battery electrolytes that have been oxidised by atmospheric oxygen, a vanadium proton exchange membrane water electrolyser was set up and investigated. Using an existing cell with a commercial and iridium-based catalyst coated membrane, it was possible to fully reduce V3.5+ and V3+ solutions to V2+ with the formation of oxygen and with coulomb efficiencies of over 96%. The cell achieved a maximum current density of 75 mA/cm2 during this process and was limited by the proximity of the V(III) reduction to the hydrogen evolution reaction. Due to the specific reaction mechanisms of V(IV) and V(III) ions, V(III) solutions were reduced with an energy efficiency of 61%, making this process nearly twice as energy efficient as the reduction of V(IV) to V(III). Polarisation curves and electrochemical impedance spectroscopy were used to further investigate the losses of half-cell reactions and to find ways of further increasing efficiency and performance levels.

  4. Vanadium oxide/polypyrrole aerogel nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Dave, B.C.; Dunn, B.S.; Wong, H.P. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering; Leroux, F.; Nazar, L.F. [Univ. of Waterloo, Ontario (Canada). Dept. of Chemistry

    1996-12-31

    Vanadium pentoxide/polypyrrole aerogel (ARG) nanocomposites were prepared by hydrolysis of VO(OC{sub 3}H{sub 7}){sub 3} using pyrrole/water/acetone mixtures. Monolithic green-black gels with polypyrrole/V ratios ranging from 0.15 to 1.0 resulted from simultaneously polymerization of the pyrrole and vanadium alkoxide precursors. Supercritical drying yielded high surface (150--200 m{sup 2}/g) aerogels, of sufficient mechanical integrity to allow them to be cut without fracturing. TEM studies of the aerogels show that they are comprised of fibers similar to that of V{sub 2}O{sub 5} ARG`s, but with a much shorter chain length. Evidence from IR that the inorganic and organic components strongly interact leads them to propose that this impedes the vanadium condensation process. The result is ARG`s that exhibit decreased electronic conductivity with increasing polymer content. Despite the unexpected deleterious effect of the conductive polymer on the bulk conductivity, at low polymer content, the nanocomposite materials show enhanced electrochemical properties for Li insertion compared to the pristine aerogel.

  5. Simulation of vanadium-48 production using MCNPX code

    Directory of Open Access Journals (Sweden)

    Sadeghi Mahdi

    2012-01-01

    Full Text Available Vanadium-48 was produced through the irradiation of the natural titanium target via the natTi(p, xn48V reaction. The titanium target was irradiated at 1 mA current and by a 21 MeV proton beam for 4 hours. In this paper, the activity of 48V, 43Sc, and 46Sc radionuclides and the efficacy of the 47Ti(p, g, 48Ti(p, n, and 49Ti(p, 2n channel reactions to form 48V radionuclide were determined using MCNPX code. Furthermore, the experimental activity of 48V was compared with the estimated value for the thick target yield produced in the irradiation time according to MCNPX code. Good agreement between production yield of the 48V and the simulation yield was observed. In conclusion, MCNPX code can be used for the estimation of the production yield.

  6. Application of vanadium incorporated phosphomolybdate supported on the modified kaolinin synthesis of diphenyl carbonate by oxidative carbonylation with phenol

    Directory of Open Access Journals (Sweden)

    Peng Meng

    2017-01-01

    Full Text Available Keggin-type molybdophosphoric acid, molybdophosphoric salt and vanadium incorporated molybdophosphoric salt supported on the modified kaolin (MK were investigated as redox co-catalysts for the oxidative carbonylation of phenol to diphenyl carbonate (DPC in the absence of solvent. The 20 wt.% of MnAMPV5 (one kind of vanadium incorporated molybdophosphoric salt loaded on MK showed the highest catalytic activity with the yield of 24.68% and a TON of 306, while the selectivity amounts to nearly 100% in all the carbonylation reactions. The catalysts were characterized by XRD, BET, XPS and H2-TPR. The reusability study showed that the catalysts were stable and active.

  7. [An in vitro study on toxic effect of vanadium-titanium-magnetite dust on alveolar macrophage in rabbits].

    Science.gov (United States)

    Song, Y; Chen, Q; Guan, Y

    1998-11-01

    To study the toxic effect of vanadium-titanium-magnetite (VTM) dust on alveolar macrophage (AM) and its hazardous extent. Survival rates, morphology and function of AM were compared in rabbits exposed to dust of VTM, vanadium oxide, titanium dioxide and silica in various doses and length of time with in vitro cell culture and putamen membrane cover glass transmission electron microscopy, and changes in activities of lactic dehydrogenase (LDH) and acid phosphatase (ACP) in cell culture were measured. Exposure to all the four kinds of dust could lead to decrease in survival rate of AM, increase in activities of LDH and ACP in the cell culture, and changes in their morphology and function to the extent dependent on the nature of dust. Toxic effect of exposure to VTM dust was lower than that to vanadium oxide and silica, but higher than that to titanium dioxide, which had slight toxic effect.

  8. Effect of silicon on the structure and mechanical properties of high-vanadium cast iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2009-07-01

    Full Text Available The results of microstructural examinations and mechanical tests carried out on Fe-C-V and Fe-C-V-Si alloys solidifying in volumetric mode, containing 1,38-1,83%C, 6,76-14,72%V and 1,05-3,69 Si, have been reported. The eutectic crystallising in Fe-C-V alloys is composed of ferrite and vanadium carbides of the VC1-x type, and as such is included in the group of fibrous eutectics. Introducing silicon additions to the Fe-C-V system changes the geometry of the solidifying eutectic from fibrous to complex regular, and the shape of primary carbides from non-faceted dendrites to the faceted ones. It has been proved that the tensile strength Rm, proof stress R0,2, unit elongation A5 and hardness HV30 depend mainly on the type of alloy matrix. It has also been proved that adding silicon to Fe-C-V alloys may increase the hardness HV30 by about 24% and the tensile strength Rm by as much as 40%, with simultaneous 80% reduction of the unit elongation A5.

  9. Cytotoxic, allergic and genotoxic activity of a nickel-titanium alloy

    NARCIS (Netherlands)

    Veldhuizen, AG; Sanders, MM; Schakenraad, JM; vanHorn, [No Value

    The nearly equiatomic nickel-titanium (NiTi) alloy is known for its shape memory properties. These properties can be put to excellent use in various biomedical applications, such as wires for orthodontic tooth alignment and osteosynthesis staples. The aim of this study was to evaluate the short-term

  10. Solution Hardening in Al-Zn Alloys. Mean Jump Distance and Activation Length of Moving Dislocations

    NARCIS (Netherlands)

    Hosson, J.Th.M. De; Boom, G.; Schlagowski, U.; Kanert, O.

    Pulsed nuclear magnetic resonance proved to be a complementary new technique for the study of moving dislocations in Al-Zn alloys. The NMR technique, in combination with strain-rate change experiments and transmission electron microscopy have been applied to study dislocation dynamics in Al-Zn

  11. Microgalvanic Corrosion Behavior of Cu-Ag Active Braze Alloys Investigated with SKPFM

    Directory of Open Access Journals (Sweden)

    Armen Kvryan

    2016-04-01

    Full Text Available The nature of microgalvanic couple driven corrosion of brazed joints was investigated. 316L stainless steel samples were joined using Cu-Ag-Ti and Cu-Ag-In-Ti braze alloys. Phase and elemental composition across each braze and parent metal interface was characterized and scanning Kelvin probe force microscopy (SKPFM was used to map the Volta potential differences. Co-localization of SKPFM with Energy Dispersive Spectroscopy (EDS measurements enabled spatially resolved correlation of potential differences with composition and subsequent galvanic corrosion behavior. Following exposure to the aggressive solution, corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. When exposed to 0.6 M NaCl, corrosion occurred at the braze-316L interface preceded by preferential dissolution of the Cu-rich phase within the braze alloy. Braze corrosion was driven by galvanic couples between the braze alloys and stainless steel as well as between different phases within the braze microstructure. Microgalvanic corrosion between phases of the braze alloys was investigated via SKPFM to determine how corrosion of the brazed joints developed.

  12. ANALYSIS OF REVERSIBLE STRUCTURAL RELAXATION IN AMORPHOUS-ALLOYS WITH THE ACTIVATION-ENERGY SPECTRUM MODEL

    NARCIS (Netherlands)

    HARUYAMA, O; Ocelik, Vaclav; ASAHI, N

    1995-01-01

    The reversible structural relaxation, which was induced by annealing treatment at about 150 K below the crystallization temperature, has been confirmed by a measurement of the residual electrical resistance at liquid-N-2 temperature for amorphous Ni68Cr14B18 and Co50Cr30B20 alloys. The temperature

  13. An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite.

    Science.gov (United States)

    Chen, Desheng; Zhao, Hongxin; Hu, Guoping; Qi, Tao; Yu, Hongdong; Zhang, Guozhi; Wang, Lina; Wang, Weijing

    2015-08-30

    An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30-40°C for 10min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0-0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H2SO4 as the stripping agent and under optimal stripping conditions (i.e., 20% H2SO4 concentration, 5:1 phase ratio (O/A), 20min stripping time, and 40°C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16g/LV2O5,0.691g/L Fe, 0.007g/L TiO2, 0.006g/L SiO2 and 0.247g/L CaO. A V2O5 product with a purity of 99.12% V2O5 and only 0.026% Fe was obtained after the oxidation, precipitation, and calcination processes. The total vanadium recovered from the hydrochloric acid leaching solution was 85.5%. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Removal of Vanadium(III) and Molybdenum(V) from Wastewater Using Posidonia oceanica (Tracheophyta) Biomass

    Science.gov (United States)

    Pennesi, Chiara; Totti, Cecilia; Beolchini, Francesca

    2013-01-01

    The use of dried and re-hydrated biomass of the seagrass Posidonia oceanica was investigated as an alternative and –low-cost biomaterial for removal of vanadium(III) and molybdenum(V) from wastewaters. Initial characterisation of this biomaterial identified carboxylic groups on the cuticle as potentially responsible for cation sorption, and confirmed the toxic-metal bioaccumulation. The combined effects on biosorption performance of equilibrium pH and metal concentrations were investigated in an ideal single-metal system and in more real-life multicomponent systems. There were either with one metal (vanadium or molybdenum) and sodium nitrate, as representative of high ionic strength systems, or with the two metals (vanadium and molybdenum). For the single-metal solutions, the optimum was at pH 3, where a significant proportion of vanadium was removed (ca. 70%) while there was ca. 40% adsorption of molybdenum. The data obtained from the more real-life multicomponent systems showed that biosorption of one metal was improved both by the presence of the other metal and by high ionic strength, suggesting a synergistic effect on biosorption rather than competition. There data ware used for the development of a simple multi-metal equilibrium model based on the non-competitive Langmuir approach, which was successfully fitted to experimental data and represents a useful support tool for the prediction of biosorption performance in such real-life systems. Overall, the results suggest that biomass of P. oceanica can be used as an efficient biosorbent for removal of vanadium(III) and molybdenum(V) from aqueous solutions. This process thus offers an eco-compatible solution for the reuse of the waste material of leaves that accumulate on the beach due to both human activities and to storms at sea. PMID:24204692

  15. A functionalized surface modification with vanadium nanoparticles of various valences against implant-associated bloodstream infection.

    Science.gov (United States)

    Wang, Jiaxing; Zhou, Huaijuan; Guo, Geyong; Cheng, Tao; Peng, Xiaochun; Mao, Xin; Li, Jinhua; Zhang, Xianlong

    2017-01-01

    Bloodstream infection, especially with implants involved, is an often life-threatening condition with high mortality rates, imposing a heavy burden on patients and medical systems. Herein, we firstly deposited homogeneous vanadium metal, V2O3, VO2, and V2O5 nanofilms on quartz glass by magnetron sputtering. Using these platforms, we further investigated the potential antimicrobial efficiency of these nano-VOx films and the interactions of human erythrocytes and bacteria (methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa) with our samples in a novel cell-bacteria coculture model. It was demonstrated that these nano-VOx precipitated favorable antibacterial activity on both bacteria, especially on S. aureus, and this effect increased with higher vanadium valence. A possible mechanism accountable for these results might be elevated levels of vanadium-induced intracellular reactive oxygen species. More importantly, based on hemolysis assays, our nano-VOx films were found to be able to kill prokaryotic cells but were not toxic to mammalian cells, holding the potential for the prevention of implant-related hematogenous infections. As far as we know, this is the first report wherein such nano-VOx films have assisted human erythrocytes to combat bacteria in a valence-dependent manner. Additionally, vanadium ions were released from these nano-VOx films in a sustained manner, and low-valence films possessed better biocompatibility with human fibroblasts. This work may provide new insights for biomedical applications of inorganic vanadium compounds and attract growing attention in this field. From the perspective of surface modification and functionalization, this study holds promise to avail the prophylaxis of bloodstream infections involving implantable biomedical devices.

  16. Improving the Ethanol Oxidation Activity of Pt-Mn Alloys through the Use of Additives during Deposition

    Directory of Open Access Journals (Sweden)

    Mohammadreza Zamanzad Ghavidel

    2015-06-01

    Full Text Available In this work, sodium citrate (SC was used as an additive to control the particle size and dispersion of Pt-Mn alloy nanoparticles deposited on a carbon support. SC was chosen, since it was the only additive tested that did not prevent Mn from co-depositing with Pt. The influence of solution pH during deposition and post-deposition heat treatment on the physical and electrochemical properties of the Pt-Mn alloy was examined. It was determined that careful control over pH is required, since above a pH of four, metal deposition was suppressed. Below pH 4, the presence of sodium citrate reduced the particle size and improved the particle dispersion. This also resulted in larger electrochemically-active surface areas and greater activity towards the ethanol oxidation reaction (EOR. Heat treatment of catalysts prepared using the SC additive led to a significant enhancement in EOR activity, eclipsing the highest activity of our best Pt-Mn/C prepared in the absence of SC. XRD studies verified the formation of the Pt-Mn intermetallic phase upon heat treatment. Furthermore, transmission electron microscopy studies revealed that catalysts prepared using the SC additive were more resistant to particle size growth during heat treatment.

  17. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Yang, Bing [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN

    2010-11-09

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  18. The role of vanadium bromoperoxidase in the biosynthesis of halogenated marine natural products.

    Science.gov (United States)

    Butler, Alison; Carter-Franklin, Jayme N

    2004-02-01

    Halogenated natural products are frequently reported metabolites in marine seaweeds. These compounds span a range from halogenated indoles, terpenes, acetogenins, phenols, etc., to volatile halogenated hydrocarbons that are produced on a very large scale. In many cases these halogenated marine metabolites possess biological activities of pharmacological interest. Given the abundance of halogenated marine natural products found in marine organisms and their potentially important biological activities, the biogenesis of these compounds has intrigued marine natural product chemists for decades. Over a quarter of a century ago, a possible role for haloperoxidase enzymes was first suggested in the biogenesis of certain halogenated marine natural products, although this was long before haloperoxidases were discovered in marine organisms. Since that time, FeHeme- and Vanadium-haloperoxidases (V-HPO) have been discovered in many marine organisms. The structure and catalytic activity of vanadium haloperoxidases is reviewed herein, including the importance of V-HPO-catalyzed bromination and cyclization of terpene substrates.

  19. First principles investigation of the activity of thin film Pt, Pd and Au surface alloys for oxygen reduction

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Hansen, Heine Anton; Rossmeisl, Jan

    2015-01-01

    Further advances in fuel cell technologies are hampered by kinetic limitations associated with the sluggish cathodic oxygen reduction reaction. We have investigated a range of different formulations of binary and ternary Pt, Pd and Au thin films as electrocatalysts for oxygen reduction. The most...... driving force for surface segregation, diffusion to defects or surface self-assembling. On the basis of stability and activity analysis we conclude that the near surface alloy of Pd in Pt and some PdAu binary and PtPdAu ternary thin films with a controlled amount of Au are the best catalysts for oxygen...

  20. Kinetics of Vanadium Extraction from Hot Metal by Basic Slag

    Science.gov (United States)

    Zhang, Tao; Xie, Bing; Liu, Xuan; Diao, Jiang; Zhang, Zhen; Li, Hong-Yi

    Extracting vanadium from vanadium containing hot metal by LD process has been proven an effective solution for the utilization of vanadium-titanium magnetite ore, but the systematic analyses of vanadium extraction rate and mechanism by basic slag are seldom reported. In this study, mathematical model of vanadium transfer from metal to slag was formulated and the rates of vanadium extraction of hot metal with basic slag were investigated. The results indicated that the apparent vanadium extraction rate constant, k p , were in the range of 1.33˜9.07×10-4g/(cm3·s). And the rate constant was increased with the increase of final slag basicity, reaction temperature and stirring gas flow. The apparent of mass transfer parameter decreases significantly from 0.13 cm3/ s to 0 cm3/ s in 20min, and the data changed as negative due to the decrease of slag oxidation and recovery of vanadium from slag to metal.

  1. Fragility–structure–conductivity relations in vanadium tellurite glass

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Yue, Yuanzheng; Rodrigues, Ana Candida Martins

    the ability to intercalate lithium-ions, it is a candidate as cathode material. Here, we investigate the correlation between liquid fragility, structure and electronic conductivity in a series of vanadium-tellurite glasses with varying vanadium concentration. We measure dynamic and thermodynamic fragility...

  2. Combined effect of vanadium and nickel on lipid peroxidation and ...

    African Journals Online (AJOL)

    use

    2011-12-12

    Dec 12, 2011 ... Signs of toxicity were observed following treatment with vanadium, not nickel nor combined vanadium and .... Kazakhstan. Animal treatment. Outbred 3-month-old male albino rats, weighing between 230 to. 235 g (mean) at the beginning of experiment, were obtained from ..... Vitamin E supplementation.

  3. Effect of reduction of strategic columbium additions in Inconel 718 alloy on the structure and properties

    Science.gov (United States)

    Ziegler, K.; Wallace, J. F.

    1982-01-01

    The amount of columbium which can be removed from Inconel alloy 718 without degrading its high temperature properties was determined. The elements that are substituted are: vanadium and tungsten together and separately; increasing the molybdenum level from 3.0% to 5.8% and increasing the boron to 0.04%.

  4. Corrosion protection of AM60B magnesium alloy by application of ...

    Indian Academy of Sciences (India)

    Cerium–vanadium (Ce–V) conversion coating was proposed as a new pretreatment for application of electroless Ni–P coating on AM60B magnesium alloy to replace the traditional chromium oxide pretreatment. Morphology and chemical composition of the conversion coating were investigated. The subsequent Ni–P ...

  5. Effect of Copper Addition on Crystallization and Properties of Hafnium Containing HITPERM Alloys

    Science.gov (United States)

    2010-05-01

    grain growth, thus increasing ther- mal stability. 3 Chromium and vanadium additions have detrimental ef- fect on magnetic properties. 4 Combined...selective oxidation of iron and formation of MO–Fe2O3 type where M=Co and/or other alloying elements spinel structures. These surface oxides do not block

  6. Catalytic activity of Pd-doped Cu nanoparticles for hydrogenation as a single-atom-alloy catalyst.

    Science.gov (United States)

    Cao, Xinrui; Fu, Qiang; Luo, Yi

    2014-05-14

    The single atom alloy of extended surfaces is known to provide remarkably enhanced catalytic performance toward heterogeneous hydrogenation. Here we demonstrate from first principles calculations that this approach can be extended to nanostructures, such as bimetallic nanoparticles. The catalytic properties of the single-Pd-doped Cu55 nanoparticles have been systemically examined for H2 dissociation as well as H atom adsorption and diffusion, following the concept of single atom alloy. It is found that doping a single Pd atom at the edge site of the Cu55 shell can considerably reduce the activation energy of H2 dissociation, while the single Pd atom doped at the top site or in the inner layers is much less effective. The H atom adsorption on Cu55 is slightly stronger than that on the Cu(111) surface; however, a larger nanoparticle that contains 147 atoms could effectively recover the weak binding of the H atoms. We have also investigated the H atom diffusion on the 55-atom nanoparticle and found that spillover of the produced H atoms could be a feasible process due to the low diffusion barriers. Our results have demonstrated that facile H2 dissociation and weak H atom adsorption could be combined at the nanoscale. Moreover, the effects of doping one more Pd atom on the H2 dissociation and H atom adsorption have also been investigated. We have found that both the doping Pd atoms in the most stable configuration could independently exhibit their catalytic activity, behaving as two single-atom-alloy catalysts.

  7. Evidence of alloy formation during the activation of graphite-supported palladium-cobalt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, F.B.; Schmal, M. [Univ. Federal do Rio de Janeiro (Brazil); Frety, R. [CNRS, Villeurbanne (France). Lab. d`Application de la Chimie a l`Environnement; Bergeret, G.; Moraweck, B. [CNRS, Villeurbanne (France). Inst. de Recherches sur la Catalyse

    1999-08-15

    Magnetism, XRD, and EXAFS analyses were used to study the formation of a solid solution on Pd-Co/G catalysts during reduction treatment. After reduction at 773 K, magnetic measurements revealed the formation of a Pd-Co alloy. XRD analysis in situ allowed one to follow the alloy process during the increase of the reduction temperature. The XRD results showed the presence of a heterogeneous solid solution after reduction at 773 K. Pd and Co K-edge EXAFS analysis confirmed that bimetallic particles with a palladium- and cobalt-rich phase were formed. The formation of a solid solution decreased the adsorption strength of 1,3-butadiene on new Pd sites modified by Co. Palladium-cobalt catalysts are useful for methanol and ethanol formation from synthesis gas at high pressure.

  8. Comparison of effects of vanadium absorbed by Coprinus comatus with those of inorganic vanadium on bone in streptozotocin-diabetic rats.

    Science.gov (United States)

    Wang, Guangbin; He, Ming; Yi, Pei; Wang, Jiashi; Li, Bin; Li, Jianjun; Fu, Yonghui; Bai, Lunhao; Fu, Qin

    2012-12-01

    The purpose of this study was to compare the effect of vanadium absorbed by Coprinus comatus (VACC) with inorganic vanadium (vanadium nitrate, IV) in preventing diabetes-related osteopenia in streptozotocin-diabetic rats. Sixty Wistar female rats used were divided into four groups: (1) normal rats (control), (2) diabetic rats, (3) diabetic rats treated with VACC, and (4) diabetic rats treated with vanadium nitrate. A standardized type 1-like diabetes model was induced by injection of streptozotocin. After the rats were treated orally with VACC and IV respectively, plasma glucose, body weights, micro-CT, biomechanical testing, and histomorphometry were examined. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. Treatments were performed over a 12-week period. Both VACC and IV have a positive effect on plasma glucose and body weights of STZ-induced diabetic rats. However, treatment with IV only caused a 39.6 % decrease in glucose levels and a 14.6 % increase in body weights, whereas VACC decreased plasma glucose and increased body weights by up to 52.2 and 24.5 %, respectively. At the same time, VACC significantly improved trabecular microstructure and mechanical strength, while IV did not exhibit desirable such effects. Also, bone Ca and bone P were not significantly increased by IV. These results indicated that both VACC and IV have hypoglycemic activity on diabetic rats, while IV did not improve bone properties. In conclusion, this study suggests that VACC improves diabetes-related bone dysfunction, primarily by improving the diabetic states.

  9. Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bo; Chen, Zhaohui; Lu, Gang [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Wang, Tianhu [School of Electrical Information and Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Ge, Yunwang, E-mail: ywgelit@126.com [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China)

    2016-04-15

    Highlights: • Hierarchical VN nanostructures were prepared on graphite foam. • Electrolyte preference of VN supercapacitor electrodes was explored. • VN showed better capacitive property in organic and alkaline electrolytes than LiCl. - Abstract: Vanadium nitride hierarchical nanostructures were prepared through an ammonia annealing procedure utilizing vanadium pentoxide nanostructures grown on graphite foam. The electrochemical properties of hierarchical vanadium nitride was tested in aqueous and organic electrolytes. As a result, the vanadium nitride showed better capacitive energy storage property in organic and alkaline electrolytes. This work provides insight into the charge storage process of vanadium nitride and our findings can shed light on other transition metal nitride-based electrochemical energy storage systems.

  10. Recent activities of association of shape memory alloys (ASMA) in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, J. [ASMA, Yokohama (Japan); Yamauchi, K. [TOKIN Corp., Sendai (Japan); Miyashita, T. [Nishimatsu Construction Co., Ltd., Yamato (Japan); Ohkata, I. [Kato Hatsujo Kaisha, Ltd., Yokohama (Japan); Narumi, S. [Sogo Hatsujo Co., Ltd. (Japan); Suzuki, Y. [Furukawa Electric Co. Ltd., Tokyo (Japan)

    1995-12-01

    The Association of Shape Memory Alloys(ASMA) was established in 1983 and systematic surveys on the Ni-Ti and Cu based SMAs were carried out until 1986. The ASMA is now reorganized as a private association. In this paper, we briefly introduce several SMA products of the member companies and present a couple of products, a static rock breaking system and a thermostatic mixing valve in detail. (orig.).

  11. Vanadium and vanadium nitride thin films grown by high power impulse magnetron sputtering

    Science.gov (United States)

    Hajihoseini, H.; Gudmundsson, J. T.

    2017-12-01

    Thin vanadium and vanadium nitride films were grown on SiO2 by non-reactive and reactive high power impulse magnetron sputtering (HiPIMS), respectively. The film properties were compared to films grown by conventional dc magnetron sputtering (dcMS) at similar conditions. We explored the influence of the stationary magnetic confinement field strength on the film properties and the process parameters. The deposition rate is much lower for non-reactive sputtering by HiPIMS than for dcMS. Furthermore, for both dcMS and HiPIMS the deposition rate is lower for strong magnetic confinement. Structural characterization was carried out using x-ray diffraction and reflection methods as well as atomic force microscopy and scanning electron microscope. Both dcMS and HiPIMS grown vanadium films are polycrystalline with similar grain size regardless of magnetic field strength. For dcMS grown vanadium films the surface roughness is higher when a strong magnetic field is used. For both non-reactive growth of vanadium and reactive growth of vanadium nitride the HiPIMS process produces denser films with lower surface roughness than dcMS does. Lowering the magnetic field strength increases the deposition rate significantly for reactive HiPIMS while it increases only slightly in the reactive dcMS case. The films grown by HiPIMS with strong magnetic confinement exhibit higher density and lower roughness. We find that the operating pressure, growth temperature, discharge voltage and film thickness has influence on the properties of HiPIMS grown vanadium nitride films. The films are denser when grown at high temperature, high discharge voltage and low pressure. The density of those films is lower for thicker films and thicker films consist of larger grain size. For all the films explored, higher density coincides with lower surface roughness. Thus, the deposition method, magnetic field strength, growth temperature, discharge voltage, film thickness and growth pressure have a significant

  12. 40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

    Science.gov (United States)

    2010-07-01

    ... for the extraction of uranium, radium and vanadium. Only vanadium byproduct production from uranium... uranium, radium and vanadium ores subcategory. 440.30 Section 440.30 Protection of Environment... SOURCE CATEGORY Uranium, Radium and Vanadium Ores Subcategory § 440.30 Applicability; description of the...

  13. Zeolite coatings on metal alloys for corrosion resistance, hydrophilicity, and microbiocidal activity

    Science.gov (United States)

    Beving, Derek Eugene

    The recent advent of polycrystalline zeolite coatings on metal alloys has heralded a paradigm shift in zeolitic application and function as well as their requisite synthesis. The prevailing paradigm for zeolite utilization and employment was through the exploitation of their uniform microporosity. We have demonstrated the utility of the non-porous as-synthesized form of high-silica-zeolite (HSZ) MFI coatings on aluminum alloys for corrosion resistance. A single chemical formulation was able to generate excellent corrosion-resistant HSZ MFI coatings on all aluminum alloys studied. Functional zeolite coatings have traditionally been synthesized as coatings comprised of single zeolite species. We have successfully generated functional zeolite hybrid coatings comprised of disparate zeolite species with controlled composition. A three-layer zeolite coating was developed to apply a low-silica-zeolite (LSZ), zeolite Y (ZY), to aluminum substrates. The middle layer was a zeolite hybrid coating of ZY crystals embedded within a MFI matrix. The mixed zeolite middle layer allowed for the adhesion of the single species HSZ MFI bottom layer to the single species LSZ ZY, top layer. A two-layer hydrophilic and antimicrobial hybrid zeolite coating on aluminum alloys was also developed. The base layer was a HSZ MFI coating and the top layer consisted of zeolite A (ZA) crystals embedded within a matrix of HSZ MFI. The ZA crystals are still present at the surface of the hybrid layer, as such; their hydrophilicity is accessible and can be exploited for their hydrophilic and antimicrobial potential. The great utility of the zeolite hybrid layer is realized with the formation of single-layer hybrid coatings on metal alloys. The hybrid coating is made of mixed inorganic crystalline species imbedded in a matrix of HSZ MFI. The inorganic species used is not limited to zeolite types; other inorganic crystalline species can be used. We have generated hybrid coatings made from LSZ ZY and HSZ

  14. Titanium oxynitride interlayer to influence oxygen reduction reaction activity and corrosion stability of Pt and Pt-Ni alloy.

    Science.gov (United States)

    Tan, XueHai; Wang, Liya; Zahiri, Beniamin; Kohandehghan, Alireza; Karpuzov, Dimitre; Lotfabad, Elmira Memarzadeh; Li, Zhi; Eikerling, Michael H; Mitlin, David

    2015-01-01

    A key advancement target for oxygen reduction reaction catalysts is to simultaneously improve both the electrochemical activity and durability. To this end, the efficacy of a new highly conductive support that comprises of a 0.5 nm titanium oxynitride film coated by atomic layer deposition onto an array of carbon nanotubes has been investigated. Support effects for pure platinum and for a platinum (50 at %)/nickel alloy have been considered. Oxynitride induces a downshift in the d-band center for pure platinum and fundamentally changes the platinum particle size and spatial distribution. This results in major enhancements in activity and corrosion stability relative to an identically synthesized catalyst without the interlayer. Conversely, oxynitride has a minimal effect on the electronic structure and microstructure, and therefore, on the catalytic performance of platinum-nickel. Calculations based on density functional theory add insight with regard to compositional segregation that occurs at the alloy catalyst-support interface. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Low-Density, Refractory Multi-Principal Element Alloys of the Cr-Nb-Ti-V-Zr System: Microstructure and Phase Analysis (Postprint)

    Science.gov (United States)

    2012-12-19

    Vanadium was in the form of chips, with a purity of 99.99%. Arc melt- ing was conducted on a water-cooled copper plate. High - purity molten...these potential new high -temperature structural alloys are explored. The alloys were prepared by vacuum arc melting followed by hot isostatic...applications of sta- tionary structures that do not suffer from high weight. Since the aerospace industry demands low-density metallic alloys for

  16. Hydrothermal Synthesis of Nanostructured Vanadium Oxides

    Directory of Open Access Journals (Sweden)

    Jacques Livage

    2010-08-01

    Full Text Available A wide range of vanadium oxides have been obtained via the hydrothermal treatment of aqueous V(V solutions. They exhibit a large variety of nanostructures ranging from molecular clusters to 1D and 2D layered compounds. Nanotubes are obtained via a self-rolling process while amazing morphologies such as nano-spheres, nano-flowers and even nano-urchins are formed via the self-assembling of nano-particles. This paper provides some correlation between the molecular structure of precursors in the solution and the nanostructure of the solid phases obtained by hydrothermal treatment.

  17. X-Ray Absorption Studies of Vanadium-Containing Metal Oxide Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hohn, Keith, L.

    2006-01-09

    Metal oxide nanocrystals offer significant potential for use as catalysts or catalyst supports due to their high surface areas and unique chemical properties that result from the high number of exposed corners and edges. However, little is known about the catalytic activity of these materials, especially as oxidation catalysts. This research focused on the preparation, characterization and use of vanadium-containing nanocrystals as selective oxidation catalysts. Three vanadium-containing nanocrystals were prepared using a modified sol-gel procedure: V/MgO, V/SiO2, and vanadium phosphate (VPO). These represent active oxidation catalysts for a number of industrially relevant reactions. The catalysts were characterized by x-ray diffraction and Raman, UV-VIS, infrared and x-ray absorption spectroscopies with the goal of determining the primary structural and chemical differences between nanocrystals and microcrystals. The catalytic activity of these catalysts was also studied in oxidative dehydrogenation of butane and methanol oxidation to formaldehyde. V/MgO nanocrystals were investigated for activity in oxidative dehydrogenation of butane and compared to conventional V/MgO catalysts. Characterization of V/MgO catalysts using Raman spectroscopy and x-ray absorption spectroscopy showed that both types of catalysts contained magnesium orthovanadate at vanadium loadings below 15 weight%, but above that loading, magnesium pyrovanadate may have been present. In general, MgO nanocrystals had roughly half the crystal size and double the surface area of the conventional MgO. In oxidative dehydrogenation of butane, nanocrystalline V/MgO gave higher selectivity to butene than conventional V/MgO at the same conversion. This difference was attributed to differences in vanadium domain size resulting from the higher surface areas of the nanocrystalline support, since characterization suggested that similar vanadium phases were present on both types of catalysts. Experiments in

  18. Thermolysis of Half-Sandwich Vanadium(V) Imido Complexes to Generate Vanadium(III) Imido Species via a Vanadium(IV) Intermediate

    NARCIS (Netherlands)

    Batinas, Aurora A.; Dam, Jeroen; Meetsma, Auke; Hessen, Bart; Bouwkamp, Marco W.

    2010-01-01

    Thermolysis of half-sandwich vanadium imido complexes Cp(RN)V(i-Pr(2)N)Me (R = p-Tol, 1a; R = t-Bu, 1b) results in a mixture of products, including vanadium(IV) dimers [CpVMe](2)(mu-RN)(2), i-Pr(2)NH, i-PrNCMe(2), CH(4), and one or more paramagnetic species. In the presence of dmpe (dmpe =

  19. Beta to alpha transformation kinetics and microstructure of Ti-6Al-4V alloy during continuous cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kherrouba, Nabil [LGSDS – ENP, Avenue Hassan Badi, 16200, El Harrach (Algeria); Research Center in Industrial Technologies CRTI, P.O. Box 64, Cheraga, 16014 (Algeria); Univ. Bretagne Sud, FRE CNRS 3744, IRDL, Rue de Saint-Maudé, F-56100, Lorient (France); Bouabdallah, Mabrouk [LGSDS – ENP, Avenue Hassan Badi, 16200, El Harrach (Algeria); Badji, Riad, E-mail: riadbadji@gmail.com [Research Center in Industrial Technologies CRTI, P.O. Box 64, Cheraga, 16014 (Algeria); Carron, Denis [Univ. Bretagne Sud, FRE CNRS 3744, IRDL, Rue de Saint-Maudé, F-56100, Lorient (France); Amir, Mounir [Research Center in Industrial Technologies CRTI, P.O. Box 64, Cheraga, 16014 (Algeria)

    2016-09-15

    In the present paper, an approach based on the Kolmogorov-Johnson-Mehl-Avrami (KJMA) model has been developed and applied to study the transformation kinetics of the β phase in Ti-6Al-4V titanium alloy during cooling. To this purpose, Differential Scanning Calorimetry (DSC) tests have been conducted using a set of cooling rates ranging from 10 to 50 °C/min. This approach allows the kinetics parameters, particularly the activation energy, to be calculated from a single DSC test using a simple linear regression. The microstructural analysis indicates that the microstructure is dominated by the α Widmanstätten morphology (α{sub W}). Microstructural observations along with the calculated values of the Avrami index and of the activation energy suggest that the growth of the α{sub W} platelets obeys a mixed mode combining the vanadium diffusion and a displacive mechanism. - Highlights: • The kinetics of the β → α phase transformation is investigated. • An approach is proposed to adapt the KJMA model for continuous cooling. • The model permits the determination of the kinetics parameters for each cooling rate. • The growth of α{sub W} plates may obey a combined displacive-diffusional growth mode. • The growth involves shear mechanism and partitioning of vanadium between α{sub W} plates.

  20. Bioavailability of vanadium extracted by EDTA, HCl, HOAC, and NaNO3 in topsoil in the Panzhihua urban park, located in southwest China.

    Science.gov (United States)

    Teng, Yanguo; Yang, Jie; Wang, Jinsheng; Song, Liuting

    2011-12-01

    Bioavailable vanadium was evaluated on the basis of soil vanadium single-extraction with ethylenediaminetetraacetic acid (EDTA), hydrochloric acid (HCl), acetic acid (HOAc), and sodium nitrate (NaNO(3)) in Panzhihua urban park. The soil vanadium concentration extracted by HOAc was 0.01-2.07 mg kg(-1), by EDTA 0.28-7.03 mg kg(-1), by NaNO(3) 0.07-0.53 mg kg(-1), and by HCl 0.19-1.36 mg kg(-1). The bioavailable vanadium (bioavailable fraction) obtained with HOAc was 0.01-1.33%, with EDTA 0.27-4.09%, with NaNO(3) 0.13-0.72%, and with HCl 0.06-0.28%. In addition, the impact of soil properties, soil nutrients, and soil enzyme activities on bioavailability of vanadium is discussed in this study. Based on the characteristics of bioavailable vanadium in the soil, ecological and health risks should have been given more attention in the studied area.

  1. Effects of NaOCl Aqueous Solutions and Ethyl Alcohol Solutions on Removing Protein Surface Contaminants and Re-establishing Antibacterial Activities of Copper-Alloyed Stainless Steel.

    Science.gov (United States)

    Kawakami, Hiroshi; Nishikubo, Hideyuki; Hirayama, Kenta; Suzuki, Satoshi; Sato, Yoshihiro; Kikuchi, Yasushi

    2015-01-01

    Effects of wiping copper-alloyed stainless steel surfaces with disinfectants to remove protein surface contaminants and re-establish their antibacterial activities were quantitatively studied. Disinfectants used were sodium hypochlorite aqueous solutions and ethyl alcohol aqueous solutions. Wiping with NaOCl aqueous solutions effectively removed protein surface contaminants. Ethyl alcohol aqueous solutions were also effective for cleaning, but their efficiency was less than that of NaOCl aqueous solutions. When the amount of residual surface contaminants was reduced to 0.4 ng/mm(2), the surfaces of the copper-alloyed stainless steel regained antibacterial activities to the same level as those in a clean surface condition.

  2. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation.

    Science.gov (United States)

    Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

    2016-01-01

    Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs) elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1) and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL). Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (<2pg/mL) from Gram-negative bacteria, seem to have negligible contribution to the danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate associated

  3. Semi-solid process of 2024 wrought aluminum alloy by strain induced melt activation

    Directory of Open Access Journals (Sweden)

    Surachai Numsarapatnuk

    2013-10-01

    Full Text Available The aim of this study is to develop a production process of a fine globular structure feedstock of the 2024 aluminumalloy suitable for subsequent semi-solid forming. The 2024 wrought aluminum alloy was first annealed to reduce the effect ofwork hardening. Then, strain was induced in the alloy by cold compression. After that the microstructural evolution duringpartial melting was investigated. The samples were subjected to full annealing at 415°C for 3 hrs prior to cold compression of40% reduction of area (RA with 3 mm/min strain rate. After that samples were partially melted at 620°C with varying holdingtime from 0 to 60 min followed by water quenching. The grain size and the average grain diameter of solid grains weremeasured using the linear intercept method. The globularization was interpreted in terms of shape factor. Liquid fraction andthe distribution of the eutectic liquid was also investigated. It was found that during partial melting, the globular morphologywas formed by the liquid wetting and fragmentation of high angle boundaries of recrystallized grains. The suitable semi-solidmicrostructure was obtained from a condition of full annealing, 40% cold working and partial melting at 620°C for 6 minholding time. The near globular grains obtained in the range of 0-60 min consisted of uniform spheroid grains with an averagegrain diameter ranged from 73 to 121 m, quenched liquid fraction was approximately 13–27% and the shape factor was greaterthan 0.6. At a holding time of less than 6 min, grain coarsening was dominant by the immigration of high-angle grainboundaries. At a longer holding time, liquid fraction increased and Ostwald ripening was dominant. The coarsening rateconstant for the 2024 Al alloy was 400.36 mm3.s-1. At a soaking time of 60 min, it was found that a minimum diameter differencewas 1.06% with coarsening index n=3 in a power law equation. The non-dendritic slug of 2024 alloy was rapid compressedinto a disc with 90%RA

  4. Method of making active magnetic refrigerant materials based on Gd-Si-Ge alloys

    Science.gov (United States)

    Pecharsky, Alexandra O.; Gschneidner, Jr., Karl A.; Pecharsky, Vitalij K.

    2006-10-03

    An alloy made of heat treated material represented by Gd.sub.5(Si.sub.xGe.sub.1-x).sub.4 where 0.47.ltoreq.x.ltoreq.0.56 that exhibits a magnetic entropy change (-.DELTA.S.sub.m) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.

  5. On the regiospecificity of vanadium bromoperoxidase.

    Science.gov (United States)

    Martinez, J S; Carroll, G L; Tschirret-Guth, R A; Altenhoff, G; Little, R D; Butler, A

    2001-04-11

    Vanadium haloperoxidase enzymes catalyze the oxidation of halide ions by hydrogen peroxide, producing an oxidized intermediate, which can halogenate an organic substrate or react with a second equivalent of hydrogen peroxide to produce dioxygen. Haloperoxidases are thought to be involved in the biogenesis of halogenated natural products isolated from marine organisms, including indoles and terpenes, of which many are selectively oxidized or halogenated. Little has been shown concerning the ability of the marine haloperoxidases to catalyze regioselective reactions. Here we report the regiospecific bromoperoxidative oxidation of 1,3-di-tert-butylindole by V-BrPO from the marine algae Ascophyllum nodosum and Corallina officinalis. Both enzymes catalyze the regiospecific oxidation of 1,3-di-tert-butylindole in a reaction requiring both H(2)O(2) and Br(-) as substrates, but which produce the unbrominated 1,3-di-tert-butyl-2-indolinone product exclusively, in near quantitative yield (i.e. one H(2)O(2) consumed per product). By contrast, reactions with the controlled addition of aqueous bromine solution (HOBr = Br(2) = Br(3)(-)) produce three monobromo and one dibromo-2-indolinone products, all of which differ from the V-BrPO-catalyzed product. Further, reactivities of 1,3-di-tert-butyl-2-indolinone with both aqueous bromine and V-BrPO differ significantly and shed light onto the possible nature of the oxidizing intermediate. This is the first example of a regiospecific bromination by a vanadium haloperoxidase and further extends their usefulness as catalysts.

  6. Platinum-Vanadium Oxide Nanotube Hybrids

    Science.gov (United States)

    Mello, Filipe L. S.; Costa, Lídia O. O.; Hernández, Eduardo Padrón; de Farias, Andréa M. Duarte; Fraga, Marco A.

    2010-06-01

    The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6-7 nm.

  7. Platinum–Vanadium Oxide Nanotube Hybrids

    Directory of Open Access Journals (Sweden)

    Hernández EduardoPadrón

    2010-01-01

    Full Text Available Abstract The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm.

  8. Large Spin Hall Angle in Vanadium Film

    Science.gov (United States)

    Wang, Tao; Fan, Xin; Wang, Wenrui; Xie, Yunsong; Warsi, Muhammad A.; Wu, Jun; Chen, Yunpeng; Lorenz, Virginia O.; Xiao, John Q.

    We report the large spin Hall angle observed in Vanadium film with small grain size and distorted lattice parameter. The spin Hall angle is quantified by measuring current-induced spin-orbit torque in V/CoFeB bilayer using optical spin torque magnetometer based on polar magneto-optical Kerr effect (MOKE). The spin Hall angle as large as θSH = -0.071 has been observed in V/CoFeB bilayer Structural analysis, using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), confirms films grown at room temperature have very small grain size and enlarged lattice parameter. The Vanadium films with distorted crystal structure also have high resistivity (>200 μΩ cm) and long spin diffusion length (~16.3 nm) measured via spin pumping experiment. This finding of spin Hall effect enhancement in more disordered structure will provide insights for understanding and exploiting materials with strong spin orbit interaction, especially in light 3d transition metals which promise long spin diffusion length.

  9. The antimicrobial activity of copper and copper alloys against nosocomial pathogens and Mycobacterium tuberculosis isolated from healthcare facilities in the Western Cape: an in-vitro study.

    Science.gov (United States)

    Mehtar, S; Wiid, I; Todorov, S D

    2008-01-01

    Clinical isolates of meticillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Candida albicans and Mycobacterium tuberculosis (MTB) were tested against copper (Cu) and its alloys. Stainless steel and polyvinylchloride (PVC) were used as controls. The amount of Cu required to inhibit test isolates at room temperature (24 degrees C) and at 4 degrees C was determined. At room temperature, Cu, DZR Brass (Cu 62%, Pb 2.5%, arsenate 0.13% and Zn 22.5%) and Brass 70/30 (Cu 70% and zinc 30%) inhibited C. albicans and K. pneumoniae at 60 min; nickel silver (NiAg) inhibited C. albicans at 60 min and K. pneumoniae at 270 min. P. aeruginosa was inhibited by Brass 70/30 and nickel silver (NiAg) at 180 min and at 270 min by Cu and DZR. Cu and DZR inhibited A. baumannii at 180 min while the other alloys were effective at 360 min. Stainless steel and PVC showed little or no inhibitory activity. Two M. tuberculosis strains, one isoniazid resistant (R267) and the other multidrug resistant (R432), demonstrated growth inhibition with Cu of 98% and 88% respectively compared with PVC; the other alloys were less active. Time to positivity (TTP) for R267 was >15 days with Cu and 11 days for the other alloys; with R432 it was 5 days. Effective inhibition of nosocomial pathogens and MTB by Cu and alloys was best when the Cu content was >55%.

  10. Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation

    Directory of Open Access Journals (Sweden)

    Feng Lili

    2011-01-01

    Full Text Available Abstract In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene were characterized by SEM, TEM, and zeta potential measurements. It is confirmed that the prepared Au@PtAg alloy nanorods/graphene hybrid composites own good catalytic function for methanol electro-oxidation by cyclic voltammograms measurements, and exhibited higher catalytic activity and more stability than pure Au@Pt nanorods and Au@AgPt alloy nanorods. In conclusion, the prepared PtAg alloy nanoislands/graphene hybrid composites own high stability and catalytic activity in methanol electro-oxidation, so that it is one kind of high-performance catalyst, and has great potential in applications such as methanol fuel cells in near future.

  11. Enhanced activity and stability of Pt–La and Pt–Ce alloys for oxygen electroreduction: the elucidation of the active surface phase

    DEFF Research Database (Denmark)

    Malacrida, Paolo; Escribano, Maria Escudero; Verdaguer Casadevall, Arnau

    2014-01-01

    in the presence of oxygen and readily oxidize. The surface oxides are completely dissolved in the electrolyte. In Pt5La and Pt5Ce the so formed Pt overlayer provides kinetic stability against the further oxidation and dissolution. At the same time, it ensures a very high stability during ORR potential cycling......Three different Pt-lanthanide metal alloys (Pt5La, Pt5Ce and Pt3La) have been studied as oxygen reduction reaction (ORR) electrocatalysts. Sputter-cleaned polycrystalline Pt5La and Pt5Ce exhibit more than a 3-fold activity enhancement compared to polycrystalline Pt at 0.9 V, while Pt3La heavily...

  12. Biological activity evaluation of magnesium fluoride coated Mg-Zn-Zr alloy in vivo.

    Science.gov (United States)

    Jiang, Hongfeng; Wang, Jingbo; Chen, Minfang; Liu, Debao

    2017-06-01

    To explore the biodegradable characteristics and biological properties, which could promote new bone formation, of MgF2 coated magnesium alloy (Mg-3wt%Zn-0.5wt%Zr) in rabbits. Magnesium alloy with MgF2 coating was made and the MgF2/Mg-Zn-Zr was implanted in the femoral condyle of rabbits. Twelve healthy adult Japanese white rabbits in weight of 2.8-3.2kg were averagely divided into A(Mg-Zn-Zr) group and B(MgF2/MgZn-Zr) group. Indexes such as microstructural evolution, SEM scan, X-ray, Micro-CT and mechanical properties were observed and detected at 1th day, 2th, 4th, 8th, 12th, 24th week after implantation. Low-density regions occurred around the cancellous bone, and the regions gradually expanded during the 12weeks after implantation. The implant was gradually absorbed from 12 to 24weeks. The density of surrounding cancellous bone increased compared with the 12th week data. The degradation rate of B group was lower than that of A group (Pmagnesium ions. The biological properties of the coating itself presented good biocompatibility and bioactivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Microstructural and Mechanical Characterization of Actively Brazed Alumina Specimens

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Cadden, C.H.; Stephens, J.J.; Glass, S.J.; Yang, N.Y.C.; Vianco, P.V.; Walker, C.A.

    1999-08-26

    Alumina (94 and 99.8% grade compositions) was brazed directly to itself with gold-based active brazing alloys (ABA's) containing vanadium additions of 1,2 and 3 weight percent. The effects of brazing conditions on the joint properties were investigated. Wetting behavior, interfacial reactions, microstructure, hermeticity and tensile strength were determined. Wetting was fair to good for the ABA and base material combinations. Microanalysis identified a discontinuous Al-V-O spinel reaction product at the alumina-braze interface. Tensile strength results for 94% alumina were uniformly good and generally not sensitive to the vanadium concentration, with tensile values of 85-105 MPa. There was more variability in the 99.8% alumina strength results, with values ranging from 25-95 MPa. The highest vanadium concentration (3 wt. %) yielded the highest joint strength for the brazed 99.8% alumina. Failures in the 99.8% alumina samples occurred at the braze-alumina interface, while the 94% alumina specimens exhibited fracture of the ceramic substrate.

  14. Crystal structure of dodecameric vanadium-dependent bromoperoxidase from the red algae Corallina officinalis.

    Science.gov (United States)

    Isupov, M N; Dalby, A R; Brindley, A A; Izumi, Y; Tanabe, T; Murshudov, G N; Littlechild, J A

    2000-06-16

    The three-dimensional structure of the vanadium bromoperoxidase protein from the marine red macroalgae Corallina officinalis has been determined by single isomorphous replacement at 2.3 A resolution. The enzyme subunit is made up of 595 amino acid residues folded into a single alpha+beta domain. There are 12 bromoperoxidase subunits, arranged with 23-point group symmetry. A cavity is formed by the N terminus of each subunit in the centre of the dodecamer. The subunit fold and dimer organisation of the Cor. officinalis vanadium bromoperoxidase are similar to those of the dimeric enzyme from the brown algae Ascophyllum nodosum, with which it shares 33 % sequence identity. The different oligomeric state of the two algal enzymes seems to reflect separate mechanisms of adaptation to harsh environmental conditions and/or to chemically active substrates and products. The residues involved in the vanadate binding are conserved between the two algal bromoperoxidases and the vanadium chloroperoxidase from the fungus Curvularia inaequalis. However, most of the other residues forming the active-site cavity are different in the three enzymes, which reflects differences in the substrate specificity and stereoselectivity of the reaction. A dimer of the Cor. officinalis enzyme partially superimposes with the two-domain monomer of the fungal enzyme. Copyright 2000 Academic Press.

  15. Synthesis, spectroscopic, DFT and in vitro biological studies of vanadium(III) complexes of aryldithiocarbonates

    Science.gov (United States)

    Andotra, Savit; Kumar, Sandeep; Kour, Mandeep; Vikas; Chayawan; Sharma, Vishal; Jaglan, Sundeep; Pandey, Sushil. K.

    2017-06-01

    Vanadium(III) tris(dithiocarbonates), [(ROCS2)3V] (R = o-, m-, p-CH3C6H4 and 4-Cl-3-CH3C6H3) and donor stabilized addition complexes [(ROCS2)2V(Cl)·L] [L = NC5H5 or P(C6H5)3] were synthesized and characterized by elemental analyses, IR, mass, TGA/DTA, SEM magnetic susceptibility and heteronuclear NMR (1H, 13C and 31P) spectroscopic studies. The cytotoxicity of the complexes was measured in vitro using the cultivated human cell lines. In addition, the antioxidant activities of the ligands and its vanadium complexes were also investigated through their scavenging effect on DPPH radicals. The antimicrobial activity of ligands and some complexes has been conducted against three bacterial strains and fungus. The density functional theory (DFT) calculations of ligands and vanadium complexes were performed by the DFT/B3LYP/LANL2DZ method to obtain the optimized molecular geometry, vibrational frequencies, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), thermodynamic properties and various other quantum-mechanical parameters.

  16. Vanadium and nickel in petroleums of bituminous Tatar rocks

    Energy Technology Data Exchange (ETDEWEB)

    Aigistova, S.Kh.; Safiullina, G.Kh.; Sadykov, A.N.; Kharlamov, V.A.

    1984-01-01

    The vanadium and nickel contents of petroleum obtained from bituminous rock of Ashal'chinsk, Akhmat, Gorskii, Katerchinsk, Klinsk (Studeno-Klyuchev), West-Chumachkin, Mordovian-Karmal' and Pokrov deposits, was determined polarographically. The vanadium concentration range in these petroleums is 0.01-0.09 and nickel 0.009-0.05 wt.%. According to results previously obtained, vanadium and nickel contents in ordinary petroleum of this country are no higher than 0.010 and 0.0014 wt.%, respectively. 3 references, 1 table.

  17. The solubility of metals in Pb-17Li liquid alloy

    Energy Technology Data Exchange (ETDEWEB)

    Borgstedt, H.U.; Feuerstein, H. (Kernforschungszentrum Karlsruhe GmbH, Inst. fuer Materialforschung, Hauptabteilung Ingenieurtechnik (Germany))

    1992-09-01

    The solubility data of iron in the eutectic alloy Pb-17Li which were evaluated from corrosion tests in a turbulent flow of the molten alloy are discussed in the frame of solubilities of the transition metals in liquid lead. It is shown that the solubility of iron in the alloy is close to that in lead. This is also the fact for several other alloying elements of steels. A comparison of all known data shows that they are in agreement with generally shown trends for the solubility of the transition metals in low melting metals. These trends indicate comparably high solubilities of nickel and manganese in the liquid metals, lower saturation concentration of vanadium, chromium, iron, and cobalt, and extremely low solubility of molybdenum. (orig.).

  18. Evaluation of self-healing ability of Ce–V conversion coating on AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Xiao Jiang

    2016-09-01

    Full Text Available This study investigated the influence of cerium nitrate in vanadate solutions on the properties of Ce–V conversion coatings on AZ31 magnesium alloys, and evaluated the self-healing behavior of the Ce–V conversion coating for AZ31 magnesium alloy. The results showed that the additions of cerium nitrate prevented pentavalent vanadium from reducing to tetravalent vanadium in the coatings during conversion reaction process. Adding appropriate cerium nitrate to vanadate solution led to a thicker coating with a more compact CeVO4 layer. The corrosion behavior of the Ce–V conversion coating was investigated by the electrochemical tests and the scratch immersion test in 3.5 wt.% NaCl solution. The self-healing ability of the coating was confirmed from all tests. The surface analysis revealed that the self-healing effect of the Ce–V conversion coating was only provided by the release and migration of vanadium compounds.

  19. Polymerization of Ethylene Catalyzed by Vanadium(III Complexes

    Directory of Open Access Journals (Sweden)

    Hamdi Ali Elagab

    2017-07-01

    Full Text Available Thirty five  complexes of 1,2- bis(benzimidazole, benzothiazole and benzoxazolebenzene,  1,2-bis(benzimidazole, benzothiazole and benzoxazole-4-methyl-benzene, 1,2-bis  (benzimidazole, benzothiazole and benzoxazole4-bromobenzene, 1, 2-bis(benzimidazole, benzothiazole and benzoxazole 4- chlorobenzene,  and 2, 6-bis(benzimidazole, benzothiazole and benzoxazole pyridine compounds with V (III metal centers were synthesized, characterized, activated with methylalumoxane (MAO and then tested for catalytic ethylene polymerization. The catalysts generally show moderate to good activities compared to the benchmark catalyst Cp2ZrCl2. The activities of the various catalysts were found to be function of the hetero atoms in the ligand frameworks and also strongly influenced by the bridging unit of the ligand. The highest activity was obtained with 36 / MAO (442 kg PE / mol cat. h. The produced polyethylenes showed high molecular weights (up to 2.7 × 106 g/mol and broad molecular weight distributions (PD = 1.4 - 16.6. Thermal analysis of polyethylenes produced with vanadium complexes revealed that the catalyst systems were capable to produce high density polyethylenes with melting temperatures > 135 °C and crystallization temperatures range from 117-120 °C with high degree of crystallinity. DOI: http://dx.doi.org/10.17807/orbital.v9i3.985 

  20. Vanadium - investigations on supply and demand of mineral raw materials

    Energy Technology Data Exchange (ETDEWEB)

    Eggert, P.; Kippenberger, C.; Kruszona, M.; Schmidt, H.; Wettig, E.

    1981-11-01

    Conclusions which are drawn in the latest report of the Federal Institute for Geosciences and Mineral Resources, Hanover, and the German Institute for Economic Research, Berlin, on the steel additive vanadium are presented.

  1. Method to Remove Uranium/Vanadium Contamination from Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, Donald R.; Morrison Stanley

    2004-07-27

    A process for removing uranium/vanadium-based contaminants from groundwater using a primary in-ground treatment media and a pretreatment media that chemically adjusts the groundwater contaminant to provide for optimum treatment by the primary treatment media.

  2. Exploring a novel approach to fabricate vanadium carbide ...

    Indian Academy of Sciences (India)

    -shell structure; composite materials; mesoporous material; solid-state reaction. ... A novel approach to the fabrication of vanadium carbide encapsulated into carbon nanotube (VC@C) core-shell structured composite by thermal treatment with ...

  3. Anthropogenic Vanadium emissions to air and ambient air concentrations in North-West Europe

    Directory of Open Access Journals (Sweden)

    Visschedijk A. H. J.

    2013-04-01

    Full Text Available An inventory of Vanadium emissions for North-West Europe for the year 2005 was made based on an identification of the major sources. The inventory covers Belgium, Germany, Denmark, France, United Kingdom, Luxembourg, Netherlands and the OSPAR region of the North Sea. Vanadium emission were calculated bottom-up using energy use activity data and collected fuel and sector-specific emissions factors, taking into account various emission control measures. The NW European emissions were dominated by combustion of heavy fuel oil and petroleum cokes. Total emissions for 2005 amounted to 1569 tons/yr. The major sources are sea going ships (39%, petroleum refineries (35% and industry (19%. Emission is strongly concentrated at the densely populated cities with major sea ports. The location of sources at or near the major port cities was confirmed by observational data, as was the downward trend in emissions due to emission control, fuel switches in industry and fuel quality improvement. The results show the positive impact of lower sulphur fuels on other possible health relevant air pollutants such as particle bound Vanadium. The emission inventory can be expanded to the full European domain and can be used to for air quality modeling and particularly for the tracing of source contributions from certain types of fossil fuels (petroleum coke and residual fuel oil. Moreover, it will allow the monitoring of changes in fuel use over time.

  4. Organometallic mediated radical polymerization of vinyl acetate using bis(imino)pyridine vanadium trichloride complexes.

    Science.gov (United States)

    Perry, Mitchell R; Allan, Laura E N; Decken, Andreas; Shaver, Michael P

    2013-07-07

    The synthesis and characterization of one novel proligand and six novel vanadium(III) trichloride complexes is described. The controlled radical polymerization activity towards vinyl acetate of these, and eight other bis(imino)pyridine vanadium trichloride complexes previously reported, is investigated. Those complexes possessing variation at the N-aryl para-position with no steric protection offered by ortho-substituents (4 examples) result in poor control over poly(vinyl acetate) polymerization. Control is improved with increasing steric bulk at the ortho-position of the N-aryl substituent (4 examples) although attempts to increase steric bulk past isopropyl were unsuccessful. Synthesizing bis(imino)pyridine vanadium trichloride complexes with substituted imine backbones restores polymerization control when aliphatic substituents are used (4 examples) but ceases to make any drastic improvements on catalyst lifetime. Modification of the polymerization conditions is also investigated, in an attempt to improve the catalyst lifetime. Expansion of the monomer scope to include other vinyl esters, particularly those derived from renewable resources, shows promising results.

  5. High Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries

    Science.gov (United States)

    2015-04-24

    Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries Siu on Tung, Krista L. Hawthorne, Yi Ding, James Mainero, and Levi T. Thompson...Automotive Research Development and Engineering Center, Warren, MI 48387, USA Keywords: nanostructured materials, lithium ion batteries , cathode...2014 to 00-00-2015 4. TITLE AND SUBTITLE High Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries 5a. CONTRACT NUMBER 5b. GRANT

  6. Tackling capacity fading in vanadium flow batteries with amphoteric membranes

    Science.gov (United States)

    Oldenburg, Fabio J.; Schmidt, Thomas J.; Gubler, Lorenz

    2017-11-01

    Capacity fading and poor electrolyte utilization caused by electrolyte imbalance effects are major drawbacks for the commercialization of vanadium flow batteries (VFB). The influence of membrane type (cationic, anionic, amphoteric) on these effects is studied by determining the excess and net flux of each vanadium ion in an operating VFB assembled with a cation exchange membrane (CEM), Nafion® NR212, an anion exchange membrane (AEM), Fumatech FAP-450, and an amphoteric ion exchange membrane (AIEM) synthesized in-house. It is shown that the net vanadium flux, accompanied by water transport, is directed towards the positive side for the CEM and towards the negative side for the AEM. The content of cation and anion exchange groups in the AIEM is adjusted via radiation grafting to balance the vanadium flux between the two electrolyte sides. With the AIEM the net vanadium flux is significantly reduced and capacity fading due to electrolyte imbalances can be largely eliminated. The membrane's influence on electrolyte imbalance effects is characterized and quantified in one single charge-discharge cycle by analyzing the content of the four different vanadium species in the two electrolytes. The experimental data recorded herewith conclusively explains the electrolyte composition after 80 cycles.

  7. Radiation resistant austenitic stainless steel alloys

    Science.gov (United States)

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  8. Stress recovery and cyclic behaviour of an Fe–Mn–Si shape memory alloy after multiple thermal activation

    Science.gov (United States)

    Hosseini, E.; Ghafoori, E.; Leinenbach, C.; Motavalli, M.; Holdsworth, S. R.

    2018-02-01

    The stress recovery and cyclic deformation behaviour of Fe–17Mn–5Si–10Cr–4Ni–1(V,C) shape memory alloy (Fe-SMA) strips, which are often used for pre-stressed strengthening of structural members, were studied. The evolution of recovery stress under different constraint conditions was studied. The results showed that the magnitude of the tensile stress in the Fe-SMA member during thermal activation can have a signification effect on the final recovery stress. The higher the tensile load in the Fe-SMA (e.g., caused by dead load or thermal expansion of parent structure during heating phase), the lower the final recovery stress. Furthermore, this study investigated the cyclic behaviour of the activated SMA followed by a second thermal activation. Although the magnitude of the recovery stress decreased during the cyclic loading, the second thermal activation could retrieve a significant part of the relaxed recovery stress. This observation suggests that the relaxation of recovery stress during cyclic loading is due to a reversible phase transformation-induced deformation (i.e., forward austenite-to-martensite transformation) rather than an irreversible dislocation-induced plasticity. Retrieval of the relaxed recovery stress by the reactivation process has important practical implications as the prestressing loss in pre-stressed civil structures can be simply recovered by reheating of the Fe-SMA elements.

  9. Application of factorial designs and Doehlert matrix in optimization of experimental variables associated with the preconcentration and determination of vanadium and copper in seawater by inductively coupled plasma optical emission spectrometry

    Science.gov (United States)

    Ferreira, Sérgio L. C.; Queiroz, Adriana S.; Fernandes, Marcelo S.; dos Santos, Hilda C.

    2002-12-01

    In the present paper a procedure for preconcentration and determination of vanadium and copper in seawater using inductively coupled plasma optical emission spectrometry (ICP OES) is proposed, which is based on solid-phase extraction of vanadium (IV), vanadium (V) and copper (II) ions as 1-(2-pyridylazo)-2-naphthol (PAN) complexes by active carbon. The optimization process was carried out using two-level full factorials and Doehlert matrix designs. Four variables (PAN mass, pH, active carbon mass and shaking time) were regarded as factors in the optimization. Results of the two-level full factorial design 2 4 with 16 runs for vanadium extraction, based on the variance analysis (ANOVA), demonstrated that the factors pH and active carbon mass, besides the interaction (pH×active carbon mass), are statistically significant. For copper, the ANOVA revealed that the factors PAN mass, pH and active carbon mass and the interactions (PAN mass×pH) and (pH×active carbon mass) are statistically significant. Doehlert designs were applied in order to determine the optimum conditions for extraction. The procedure proposed allowed the determination of vanadium and copper with detection limits (3σ/ S) of 73 and 94 ng l -1, respectively. The precision, calculated as relative standard deviation (R.S.D.), was 1.22 and 1.37% for 12.50 μg l -1 of vanadium and copper, respectively. The preconcentration factor was 80. The recovery achieved for determination of vanadium and copper in the presence of several cations demonstrated that this procedure improved the selectivity required for seawater analysis. The procedure was applied to the determination of vanadium and copper in seawater samples collected in Salvador City, Brazil. Results showed good agreement with other data reported in the literature.

  10. Localization of Vanabins, Vanadium-Binding Proteins, in the Blood Cells of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea(Physiology)

    OpenAIRE

    Nobuo, Yamaguchi; Yuko, Amakawa; Hiroshi, Yamada; Tatsuya, Ueki; Hitoshi, Michibata; Marine Biological Laboratory, Graduate School of Science, Hiroshima University; Department of Neuroscience, Graduate School of Medicine and Dentistry, Okayama University; Molecular Physiology Laboratory, Department of Biological Science, Graduate School of Science, Hiroshima University

    2006-01-01

    Some species of the family Ascidiidae accumulate vanadium in concentrations in excess of 350mM, which is about 10^7-fold higher than the concentration of vanadium in seawater. In these species, signet ring cells with a single large vacuole in which vanadium ions are contained function as vanadium-accumulating cells. These have been termed vanadocytes. We recently isolated five vanadium-binding proteins, which we named Vanabinl, Vanabin2, Vanabin3, Vanabin4, and VanabinP, from vanadocytes of t...

  11. Characterization of vanadium bromoperoxidase from Macrocystis and Fucus: reactivity of vanadium bromoperoxidase toward acyl and alkyl peroxides and bromination of amines.

    Science.gov (United States)

    Soedjak, H S; Butler, A

    1990-08-28

    Vanadium bromoperoxidase (V-BrPO) has been isolated and purified from the marine brown algae Fucus distichus and Macrocystis pyrifera. V-BrPO catalyzes the oxidation of bromide by hydrogen peroxide, resulting in the bromination of certain organic acceptors or the formation of dioxygen. V-BrPO from F. distichus and M. pyrifera have subunit molecular weights of 65,000 and 74,000, respectively, and specific activities of 1580 units/mg (pH 6.5) and 1730 units/mg (pH 6) for the bromination of monochlorodimedone, respectively. As isolated, the enzymes contain a substoichiometric vanadium/subunit ratio; the vanadium content and specific activity are increased by addition of vanadate. V-BrPO (F. distichus, M. pyrifera, and Ascophyllum nodosum) also catalyzes the oxidation of bromide using peracetic acid. In the absence of an organic acceptor, a mixture of oxidized bromine species (e.g., hypobromous acid, bromine, and tribromide) is formed. Bromamine derivatives are formed from the corresponding amines, while 5-bromocytosine is formed from cytosine. In all cases, the rate of the V-BrPO-catalyzed reaction is much faster than that of the uncatalyzed oxidation of bromide by peracetic acid, at pH 8.5, 1 mM bromide, and 2 mM peracetic acid. In contrast to hydrogen peroxide, V-BrPO does not catalyze formation of dioxygen from peracetic acid in either the presence or absence of bromide. V-BrPO also uses phenylperacetic acid, m-chloroperoxybenzoic acid, and p-nitroperoxybenzoic acid to catalyze the oxidation of bromide; dioxygen is not formed with these peracids. V-BrPO does not catalyze bromide oxidation or dioxygen formation with the alkyl peroxides ethyl hydroperoxide, tert-butyl hydroperoxide, and cuminyl hydroperoxide.

  12. Preparation and Photocatalytic Activity of Potassium- Incorporated Titanium Oxide Nanostructures Produced by the Wet Corrosion Process Using Various Titanium Alloys

    Directory of Open Access Journals (Sweden)

    So Yoon Lee

    2015-08-01

    Full Text Available Nanostructured potassium-incorporated Ti-based oxides have attracted much attention because the incorporated potassium can influence their structural and physico-chemical properties. With the aim of tuning the structural and physical properties, we have demonstrated the wet corrosion process (WCP as a simple method for nanostructure fabrication using various Ti-based materials, namely Ti–6Al–4V alloy (TAV, Ti–Ni (TN alloy and pure Ti, which have 90%, 50% and 100% initial Ti content, respectively. We have systematically investigated the relationship between the Ti content in the initial metal and the precise condition of WCP to control the structural and physical properties of the resulting nanostructures. The WCP treatment involved various concentrations of KOH solutions. The precise conditions for producing K-incorporated nanostructured titanium oxide films (nTOFs were strongly dependent on the Ti content of the initial metal. Ti and TAV yielded one-dimensional nanowires of K-incorporated nTOFs after treatment with 10 mol/L-KOH solution, whereas TN required a higher concentration (20 mol/L-KOH solution to produce comparable nanostructures. The obtained nanostructures revealed a blue-shift in UV absorption spectra due to the quantum confinement effects. A significant enhancement of the photocatalytic activity was observed via the chromomeric change and the intermediate formation of methylene blue molecules under UV irradiation. This study demonstrates the WCP as a simple, versatile and scalable method for the production of nanostructured K-incorporated nTOFs to be used as high-performance photocatalysts for environmental and energy applications.

  13. Vanadium(IV/V) speciation of pyridine-2,6-dicarboxylic acid and 4-hydroxy-pyridine-2,6-dicarboxylic acid complexes: potentiometry, EPR spectroscopy and comparison across oxidation states.

    Science.gov (United States)

    Jakusch, Tamás; Jin, Wenzheng; Yang, Luqin; Kiss, Tamás; Crans, Debbie C

    2003-05-01

    Evaluation of stability of vanadium(IV) and (V) complexes under similar conditions is critical for the interpretation and assessment of bioactivity of various vanadium species. Detailed understanding of the chemical properties of these complexes is necessary to explain differences observed their activity in biological systems. These studies are carried out to link the chemistry of both vanadium(IV) and (V) complexes of two ligands, 2,6-pyridinedicarboxylic acid (dipicolinic acid, H(2)dipic) and 4-hydroxy-2,6-pyridinedicarboxylic acid (H(2)dipic-OH). Solution speciation of the two 2,6-pyridinedicarboxylic acids with vanadium(IV) and vanadium(V) ions was determined by pH-potentiometry at I=0.2 M (KCl) ionic strength and at T=298 K. The stability and the metal affinities of the ligands were compared. Vanadium(V) complexes were found to form only tridentate coordinated 1:1 complexes, while vanadium(IV) formed complexes with both 1:1 and 1:2 stoichiometries. The formation constant reflects hindered coordination of a second ligand molecule, presumably because of the relatively small size of the metal ion. The most probable binding mode of the complexes was further explored using ambient and low temperature EPR spectroscopy for vanadium(IV) and 51V NMR spectroscopy for vanadium(V) systems. Upon complex formation the pyridinol-OH in position 4 deprotonates with pK approximately 3.7-4.1, which is approximately 6 orders of magnitude lower than that of the free ligand. The deprotonation enhances the ligand metal ion affinity compared to the parent ligand dipicolinic acid. In the light of the speciation and stability data of the metal complexes, the efficiency of the two ligands in transporting the metal ion in the two different oxidation states are assessed and discussed.

  14. DEVELOPMENT OF THE COMPLEX-ALLOYED STEEL OF INCREASED HARDENABILITY, VISCOSITY AND HEAT-RESISTANCE FOR CUTTING PARTS OF HIGH-SPEED INSTRUMENT, OPERATING IN CONDITIONS OF HEATING UP AND DYNAMIC LOADS

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2006-01-01

    Full Text Available The theoretical aspects of development of the complex-alloyed steel compounds for cutting parts of high-speed instrument, particularly influence of alloying elements on its structure and characteristics are considered. It is shown that combined alloying of steel by carbon, chrome, silicon, manganese, vanadium and molybdenum in a certain proportion allows to reach the intended aim, achieving at the same time increase of solidity, impact elasticity and heat stability.

  15. Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

    2018-02-01

    Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

  16. Synthesis of a new insulin-mimetic anti-diabetic drug containing vitamin A and vanadium(IV) salt: Chemico-biological characterizations.

    Science.gov (United States)

    Adam, Abdel Majid A; Naglah, Ahmed M; Al-Omar, Mohamed A; Refat, Moamen S

    2017-09-01

    Diabetes patients suffer from chronic disorders in the metabolism due to high blood sugar caused by anomalies in insulin excretion. Recently, vanadium compounds have been prepared and functionalized to decrease the level of hyperglycemia. Vitamin A boosts beta cell activity; therefore, the lack of this vitamin plays a role in the development of type 2 diabetes. The aim of this article focused on the synthesis of a new anti-diabetic drug formed from the complexation of a vanadium(IV) salt with vitamin A. Vitamin A acts as a unidentate chelate through the oxygen of its -OH group. The vanadium(IV) compound is surrounded by two vitamin A molecules. The [VO(vitamin A)2(H2O)2] compound was synthesized in a binary solvent system consisting of MeOH/H2O (1:1 ratio) in alkaline media at pH = 8. This compound was characterized using Fourier transform infrared spectra (FT-IR), electronic spectra (UV-vis), effective magnetic moment, electron spin resonance (ESR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermal analysis (thermogravimetry (TG)-differential thermal analysis (DTA)). Anti-diabetic efficiency for the vanadium(IV) compound was assessed in streptozotocin (STZ)-induced diabetic mice. The results of the animal studies demonstrate the ability of the vanadium(IV) complex to act as an anti-diabetic agent, as measured by improvements of lipid profile, antioxidant activity (superoxide dismutase), malondialdehyde (MDA), glutathione, methionine synthase, and kidney and liver functions.

  17. Material composition and nuclear data libraries' influence on nickel-chromium alloys activation evaluation: a comparison with decay heat experiments

    CERN Document Server

    Cepraga, D G

    2000-01-01

    The paper presents the activation analyses on Inconel-600 nickel-chromium alloy. Three activation data libraries, namely the EAF-4.1, the EAF-97 and the FENDL/A-2, and the FENDL/D-2 decay data library, have been used to perform the calculation with the European activation code ANITA-4/M. The neutron flux distribution into the material samples was provided by JAERI as results of 3D Monte-Carlo MCNP transport code experiment simulation. A comparison with integral decay heat measurement performed at the Fusion Neutronics Source (FNS), JAERI, Tokai, Japan, is used to validate the computational approach. The calculation results are given and discussed. The impact of the material composition, including impurities, on the decay heat of samples irradiated in fusion-like neutron spectra is assessed and discussed. The discrepancies calculations-experiments are within the experimental errors, that is between 6% and 10%, except for the short cooling times (less than 40 min after the end of irradiation). To improve calcul...

  18. Tension-Enhanced Hydrogen Evolution Reaction on Vanadium Disulfide Monolayer

    Science.gov (United States)

    Pan, Hui

    2016-02-01

    Water electrolysis is an efficient way for hydrogen production. Finding efficient, cheap, and eco-friendly electrocatalysts is essential to the development of this technology. In the work, we present a first-principles study on the effects of tension on the hydrogen evolution reaction of a novel electrocatalyst, vanadium disulfide (VS2) monolayer. Two electrocatalytic processes, individual and collective processes, are investigated. We show that the catalytic ability of VS2 monolayer at higher hydrogen coverage can be efficiently improved by escalating tension. We find that the individual process is easier to occur in a wide range of hydrogen coverage and the collective process is possible at a certain hydrogen coverage under the same tension. The best hydrogen evolution reaction with near-zero Gibbs free energy can be achieved by tuning tension. We further show that the change of catalytic activity with tension and hydrogen coverage is induced by the change of free carrier density around the Fermi level, that is, higher carrier density, better catalytic performance. It is expected that tension can be a simple way to improve the catalytic activity, leading to the design of novel electrocatalysts for efficient hydrogen production from water electrolysis.

  19. Vanadium sulfides interwoven nanoflowers based on in-situ sulfurization of vanadium oxides octahedron on nickel foam for efficient hydrogen evolution

    Science.gov (United States)

    Rao, Yi; Zhang, Li-Ming; Shang, Xiao; Dong, Bin; Liu, Yan-Ru; Lu, Shan-Shan; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-11-01

    Novel vanadium sulfides interwoven nanoflowers supported on nickel foam (VO-S/NF) has been synthesized through a facile two-step access. Firstly, octahedron-structured vanadium oxides as precursor were anchored on the surface of NF (VO/NF) by a hydrothermal process. Secondly, in-situ sulfurization in H2S gas has been applied to prepare VO-S/NF. XRD shows that VO-S/NF sample is composed of mixture phases including VS and Ni3S2, implying the interface effect between VS and Ni3S2. SEM images demonstrate that octahedron-structured VO from VO/NF changed to VO-S interwoven nanoflowers on VO-S/NF, which are composed of vertical interwoven nanosheets. It can enlarge surface area to expose abundant active sites and facilitate mass and charge transportation. The electrochemical measurements display the enhanced HER activity of VO-S/NF requiring an overpotential of 165 mV to deliver 10 mA cm-2, which may be ascribed to the novel structure of VS interwoven nanosheets and the synergistic effect between VS and Ni3S2. Furthermore, VO-S/NF remains high HER activity for at least 10 h with excellent structural stability confirmed by post-HER characterization such as XRD, SEM and XPS. Therefore, it may provide a new way to design multiple transition metal sulfides-based electrocatalysts with unique nanostructure as well as interface effect for HER in alkaline.

  20. A high-performance catalyst support for methanol oxidation with graphene and vanadium carbonitride.

    Science.gov (United States)

    Huang, Taizhong; Mao, Shun; Zhou, Guihua; Zhang, Zhaoliang; Wen, Zhenhai; Huang, Xingkang; Ci, Suqin; Chen, Junhong

    2015-01-28

    In this study, a graphene-vanadium carbonitride (G-V(C, N)) hybrid is reported as a novel support for the Pt catalyst in methanol oxidation. The catalytic activity of the Pt/G-V(C, N) hybrid for methanol oxidation is greatly enhanced compared with that of a commercial Pt/C catalyst with carbon black as the catalyst support. The outstanding catalytic activity of the Pt/G-V(C, N) catalyst suggests the potential of using graphene-metal carbonitride as the catalyst support in fuel cells.

  1. X-ray absorption of Azotobacter vinelandii vanadium nitrogenase

    Energy Technology Data Exchange (ETDEWEB)

    George, G.N.; Coyle, C.L.; Hales, B.J.; Cramer, S.P.

    1988-06-08

    Evidence for the existence of a vanadium-containing nitrogenase has existed for more than half a century, but progress in understanding this enzyme has only come recently. In 1980, Bishop and co-workers proposed that an alternative nitrogen-fixing enzyme exists in Azotobacter vinelandii and subsequently proposed that vanadium was involved. In 1986, Robson et al. demonstrated clearly that the alternate nitrogenase from Azotobacter chroococcum, Acl*, contained vanadium instead of molybdenum. Hales et al. have shown the vanadium is also found in the Azotobacter vinelandii alternative component I, Avl'. The molybdenum and vanadium nitrogenase proteins are similar in many respects. Like the molybdenum enzyme, both Acl* and Avl' exhibit an EPR spectrum characteristic of a species with an S = 3/2 ground state; Avl' also contains the so-called P-clusters. Additionally Acl* has recently been shown to possess an N-methylformamide soluble cofactor, FeVco, analogous to the well-known iron-molybdenum cofactor FeMoco. Arber et al. have reported X-ray absorption spectra for the Acl* enzyme and interpreted the EXAFS as evidence for a V-Fe-S cluster. The local vanadium structure is proposed to resemble a recently synthesized cubane-like VFe/sub 3/S/sub 4/ cluster, and analogies are drawn with the EXAFS-derived structure reported for the molybdenum nitrogenases. The authors report herein an X-ray absorption spectroscopic study of A. vinelandii vanadium nitrogenase, Avl', which supports and extends the work of Arber et al.

  2. Vanadium-Catalyzed Enantioselective Desymmetrization of meso-Secondary Allylic Alcohols and Homoallylic Alcohols

    OpenAIRE

    Li, Zhi; Zhang, Wei; Hisashi Yamamoto, H.

    2008-01-01

    Vanadium-catalyzed epoxidation has extended substrate scope. In addition to various bis-allylic alcohols, bis-homoallylic alcohols can also be desymmetrized using our Vanadium-Bis-hydroxamic acid complexes.

  3. Complexation of vanadium with amidoxime and carboxyl groups. Uncovering the competitive role of vanadium in uranium extraction from seawater

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cong-Zhi; Wu, Qun-Yan; Lan, Jian-Hui; Shi, Wei-Qun [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Chai, Zhi-Fang [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Soochow Univ., Suzhou (China). School of Radiological and Interdisciplinary Sciences (RAD-X); Wu, Guo-Zhong [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Applied Physics

    2017-09-01

    At present, amidoxime-based adsorbents are considered to be the most promising materials for extraction of uranium from seawater. However, the high concentrations of transition metals especially vanadium strongly compete with uranium in the sequestration process, which is extremely limited the commercial use of amidoxime-based adsorbents. In this work, the coordination modes, bonding nature, and stabilities of possible vanadium(IV) (VO{sup 2+}) and (V) (VO{sub 2}{sup +}, VO{sup 3+}, V{sup 5+}) complexes with amidoximate (AO{sup -}), carboxyl (Ac{sup -}), glutarimidedioximate (HA{sup -}) and deprotonated glutarimidedioximate (A{sup 2-}) on single and double alkyl chains (R=C{sub 13}H{sub 26}) are systematically explored by quantum chemical calculations. Different from the uranyl (UO{sub 2}{sup 2+}) complexes, the AO{sup -} groups of the vanadium(IV) and (V) complexes prefer to coordinate as monodentate and chelate ligands, while few species with AO{sup -} groups in η{sup 2}-binding mode have been observed in the vanadium complexes. Besides, the vanadium complexes are predicted to have obvious covalent metal-ligand bonds. According to thermodynamic stability analysis, all the vanadium complexes with AO{sup -}, Ac{sup -}, HA{sup -} and A{sup 2-} ligands on double alkyl chains are found to be more stable than corresponding complexes with ligands on a single chain. The synergistic effect of the amidoxime and carboxyl groups can be observed in most of VO{sub 2}{sup +} and VO{sup 3+} complexes with mixed ligands (AO{sup -}/Ac{sup -}). The vanadium(IV) and (V) complexes are more stable than the corresponding uranyl complexes, and the adsorption capability of the amidoxime-based adsorbents toward vanadium(V) ions decrease in the order of VO{sub 2}{sup +}>VO{sup 3+}> V{sup 5+}. The dioxovanadium cation VO{sub 2}{sup +} is predicted to form multinuclear vanadium complex in the sequestration process, possibly resulting in higher stable VO{sub 2}{sup +} complexes. Therefore

  4. Interaction of Ti and Cr atoms with point defects in bcc vanadium: A DFT study

    Science.gov (United States)

    Boev, A. O.; Aksyonov, D. A.; Kartamyshev, A. I.; Maksimenko, V. N.; Nelasov, I. V.; Lipnitskii, A. G.

    2017-08-01

    The development of low-swelling radiation-resistant alloys is vital for the creation of reliable fusion reactors. In this article, we revisit the long-standing problem of very low radiation swelling in V-Ti-Cr alloys by means of DFT calculations. In particular, we study double and triple interactions of point defects such as solutes, vacancies and self-interstitial atoms in bcc V. According to our results titanium atom and vacancy are strongly attracted and in addition to pairs form highly stable triple Ti-Vacancy-Ti complexes, which are absent in the case of chromium. By using an analytic model of void growth and using calculated binding energies of point defect complexes in bcc vanadium we obtain three orders of magnitude reduction of swelling rate due to the formation of Ti-Vacancy-Ti complexes, which allows to explain experimental observations. Finally, we explain the causes of the strong attraction between titanium and vacancy using geometry and electronic structure analysis.

  5. Effect of transition metal impurities on the strength of grain boundaries in vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xuebang; Kong, Xiang-Shan; You, Yu-Wei; Liu, Wei; Liu, C. S., E-mail: csliu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Chen, Jun-Ling; Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2016-09-07

    Effects of 3d (Ti-Ni), 4d (Zr-Pd), and 5d (Hf-Pt) transition metal impurities on strength of two representative vanadium grain boundaries (GBs), symmetric Σ3(111) and asymmetric Σ5(210), were studied by first-principles calculations within the framework of the Rice-Wang thermodynamic model and within the computational tensile test. The desirable elements to increase the GB cohesion were predicted based on their segregation and strengthening behaviors across the different GB sites. It reveals that the elements Ti, Zr, Hf, Nb, and Ta are good choices for the GB cohesion enhancers. In addition, the GB strengthening by solutes is sensitive to the GB structures. The elements Cr, Mn, Fe, Co, and Ni decrease the GB strength of the Σ3(111) GB but they can increase the cohesion of the Σ5(210) GB. Furthermore, the origin of Ti-induced change of the GB strength was uncovered by analyzing the atomic bonds and electronic structures as well as the tensile strength. This work provides a theoretical guidance to screen promising alloying elements in V-based materials with improved resistance to GB decohesion and also helps us to understand the formation mechanism of Ti-rich precipitates in the V-Cr-Ti alloys under neutron or ion irradiation environments.

  6. Ameliorative effect of vanadium on oxidative stress in stomach tissue of diabetic rats

    Science.gov (United States)

    Yilmaz-Ozden, Tugba; Kurt-Sirin, Ozlem; Tunali, Sevim; Akev, Nuriye; Can, Ayse; Yanardag, Refiye

    2014-01-01

    Between their broad spectrum of action, vanadium compounds are shown to have insulin mimetic/enhancing effects. Increasing evidence in experimental and clinical studies suggests that oxidative stress plays a major role in the pathogenesis of diabetes and on the onset of diabetic complications. Thus, preventive therapy can alleviate the possible side effects of the disease. The aim of the present study was to investigate the effect of vanadyl sulfate supplementation on the antioxidant system in the stomach tissue of diabetic rats. Male Swiss albino rats were randomly divided into 4 groups: control; control+vanadyl sulfate; diabetic; diabetic+vanadyl sulfate. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ; 65 mg/kg body weight). Vanadyl sulfate (100 mg/kg body weight) was given daily by gavage for 60 days. At the last day of the experiment, stomach tissues were taken and homogenized to make a 10% (w/v) homogenate. Catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST), myeloperoxidase (MPO), carbonic anhydrase (CA), glucose-6-phosphate dehydrogenase (G6PD) and lactate dehydrogenase (LDH) activities were determined in the stomach tissue. CAT, SOD, GR, GPx, GST, CA, G6PD and LDH activities were increased in diabetic rats when compared to normal rats. Vanadium treatment significantly reduced the elevated activities of GR, GPx, GST compared with the diabetic group whereas the decreases in CAT, SOD, CA, G6PD and LDH activities were insignificant. No significant change was seen for MPO activity between the groups. It was concluded that vanadium could be used for its ameliorative effect against oxidative stress in diabetes. PMID:24856383

  7. Engineering the Activity and Stability of Pt-Alloy Cathode Fuel-Cell Electrocatalysts by Tuning the Pt-Pt Distance

    DEFF Research Database (Denmark)

    Escribano, Maria Escudero; Malacrida, Paolo; Vej-Hansen, Ulrik Grønbjerg

    2014-01-01

    One of the main obstacles to the commercialisation of low-temperature fuel cells is the slow kinetics of the oxygen reduction reaction (ORR). In order to decrease the ORR overpotential and reduce the Pt loading we need to develop more active and stable electrocatalysts. A fruitful strategy...... for enhancing the cathode activity is to alloy Pt with transition metals [1-2]. However, alloys of Pt and late transition metals are typically unstable under fuel-cell conditions. Herein, we present experimental and theoretical studies showing the trends in activity and stability of novel cathode catalysts...... based on alloys of Pt and lanthanides. Sputter-cleaned, polycrystalline Pt5Gd shows a five-fold increase in ORR activity [3], relative to Pt at 0.9 V in 0.1 M HClO4. The rest of the Pt5Ln (Ln = lanthanide) tested present at least a 3-fold enhancement in activity [4,5]. In all cases, a Pt overlayer...

  8. Vanadium uptake by biomass of Coprinus comatus and their effect on hyperglycemic mice.

    Science.gov (United States)

    Han, Chunchao; Cui, Bo; Wang, Yingzi

    2008-07-01

    The Vanadium uptake by Coprinus comatus and their co-effect on hyperglycemic mice were studied. By fermentation and AAS analysis, the optimal concentration of vanadium in medium was 0.4%, and the content of vanadium accumulated in the mycelia was 3,528.0 microg/g. At the concentration of 0.4%, the vanadium-associated toxicity was reduced, and its anti-diabetic effects were maintained.

  9. A Novel Eco-Friendly Vanadium Precipitation Method by Hydrothermal Hydrogen Reduction Technology

    OpenAIRE

    Guobin Zhang; Yimin Zhang; Shenxu Bao; Jing Huang; Liuhong Zhang

    2017-01-01

    In view of the serious pollution problems caused by the traditional vanadium precipitation process, the eco-friendly technology of hydrothermal hydrogen reduction was first applied to precipitate phase pure vanadium sesquioxide (V2O3) products from stripped pentavalent vanadium (V (V)) solution extracted from vanadium-bearing shale. Thermodynamic analysis demonstrate the method of hydrothermal hydrogen reduction is feasible for precipitating V2O3 from V (V) solution at a suitable pH range, an...

  10. One-pot preparation of nanoporous Ag-Cu@Ag core-shell alloy with enhanced oxidative stability and robust antibacterial activity.

    Science.gov (United States)

    Liu, Xue; Du, Jing; Shao, Yang; Zhao, Shao-Fan; Yao, Ke-Fu

    2017-08-31

    Metallic core-shell nanostructures have inspired prominent research interests due to their better performances in catalytic, optical, electric, and magnetic applications as well as the less cost of noble metal than monometallic nanostructures, but limited by the complicated and expensive synthesis approaches. Development of one-pot and inexpensive method for metallic core-shell nanostructures' synthesis is therefore of great significance. A novel Cu network supported nanoporous Ag-Cu alloy with an Ag shell and an Ag-Cu core was successfully synthesized by one-pot chemical dealloying of Zr-Cu-Ag-Al-O amorphous/crystalline composite, which provides a new way to prepare metallic core-shell nanostructures by a simple method. The prepared nanoporous Ag-Cu@Ag core-shell alloy demonstrates excellent air-stability at room temperature and enhanced oxidative stability even compared with other reported Cu@Ag core-shell micro-particles. In addition, the nanoporous Ag-Cu@Ag core-shell alloy also possesses robust antibacterial activity against E. Coli DH5α. The simple and low-cost synthesis method as well as the excellent oxidative stability promises the nanoporous Ag-Cu@Ag core-shell alloy potentially wide applications.

  11. Enhancing the Performance of Vanadium Redox Flow Batteries using Quinones

    Science.gov (United States)

    Mulcahy, James W., III

    The global dependence on fossil fuels continues to increase while the supply diminishes, causing the proliferation in demand for renewable energy sources. Intermittent renewable energy sources such as wind and solar, require electrochemical storage devices in order to transfer stored energy to the power grid at a constant output. Redox flow batteries (RFB) have been studied extensively due to improvements in scalability, cyclability and efficiency over conventional batteries. Vanadium redox flow batteries (VRFB) provide one of the most comprehensive solutions to energy storage in relation to other RFBs by alleviating the problem of cross-contamination. Quinones are a class of organic compounds that have been extensively used in chemistry, biochemistry and pharmacology due to their catalytic properties, fast proton-coupled electron transfer, good chemical stability and low cost. Anthraquinones are a subcategory of quinones and have been utilized in several battery systems. Anthraquinone-2, 6-disulfonic acid (AQDS) was added to a VRFB in order to study its effects on cyclical performance. This study utilized carbon paper electrodes and a Nafion 117 ion exchange membrane for the membrane-electrode assembly (MEA). The cycling performance was investigated over multiple charge and discharge cycles and the addition of AQDS was found to increase capacity efficiency by an average of 7.6% over the standard VRFB, while decreasing the overall cycle duration by approximately 18%. It is thus reported that the addition of AQDS to a VRFB electrolyte has the potential to increase the activity and capacity with minimal increases in costs.

  12. A new sensitive electrochemical method for the determination of vanadium(IV) and vanadium(V) in Benfield sample.

    Science.gov (United States)

    Qureshi, Munawar Saeed; Mohd Yusoff, Abdull Rahim bin; Shah, Afzal; Nafady, Ayman; Sirajuddin

    2015-01-01

    Vanadium(IV) and vanadium(V) can be determined by using differential pulse cathodic stripping voltammetry technique (DPCSV). Cupferron (ammonium N-nitrosophenylhydroxylamine) was used as ligand to form complex compounds with vanadium ions in Britton-Robinson buffer (BRB) solution. At concentration lower than 1.0×10(-6) M, both V(IV) and V(V) cupferron complexes showed a single cathodic peak at -0.576 V in BRB of pH 4; thus V(IV) and V(V) ions cannot be differentiated at low concentration. However, the ionic species of vanadium can be differentiated at high concentration in the presence of cupferron. Parameters including pH of BRB solution, initial potential and accumulation potential were optimized. Under the optimized parameters, the limit of detection (LOD) was 0.09 nM, and the peak current was linear in the concentration range 0.01-0.9 µM total vanadium ions. The determination of V(IV) and V(V) ions was carried out at higher concentration in the sample using calibration plot method. At higher concentration range of 10-60 µM V(IV) and V(V) ions were determined with LOD of 1.2 and 1.1 µM, respectively. The developed method was successfully applied to 10,00,000 fold diluted Benfield sample and 0.6227 M total vanadium ions were determined. The determination of V(IV) and V(V) ions were also successfully carried out in artificial sample as well as Benfield sample (dilution factor, 10,000). The concentration of V(IV) and V(V) ions was 22.52 µM and 38.91 µM, respectively, giving total vanadium concentration of 0.6143 M in Benfield sample. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Gastroprotective effect of vanadium in rats - the roles of gastric acid ...

    African Journals Online (AJOL)

    Vanadium (various forms) has been proven to be beneficial in the treatment of certain diseases, especially diabetes. Reports have it that vanadium may protect the stomach from gastric ulcerogens such as ethanol and acid. This study was designed to investigate the probable mechanism Vanadium exerts its' ...

  14. Method for Vanadium Speciation in Aqueous Samples by HPLC-ICP ...

    African Journals Online (AJOL)

    Method for Vanadium Speciation in Aqueous Samples by HPLC-ICP-OES. M Hu, PP Coetzee. Abstract. A method for vanadium speciation is proposed. The method uses a low concentration eluent, 10 mmol L–1 EDTA and 14 mmol L–1 sodium carbonate, for the ion chromatographic separation of vanadium species at a ...

  15. Method for Vanadium Speciation in Aqueous Samples by HPLC-ICP ...

    African Journals Online (AJOL)

    NJD

    methods can only measure the total concentration of vanadium, or one of the two vanadium species, particularly V(V).4–6 Some two-step methods for the determination of the two vanadium species7–10 have been proposed by several groups. These methods normally measure one of the two species in one step, and in the.

  16. Vanadium Extraction from Refractory Stone Coal Using Novel Composite Additive

    Science.gov (United States)

    Cai, Z. L.; Zhang, Y. M.; Liu, T.; Huang, J.

    2015-11-01

    Based on the novel composite additive BaCO3/CaO for the vanadium extraction from the refractory stone coal, the vanadium leaching effect has been investigated and many technical conditions have also been optimized. The results indicated that an optimum vanadium leaching efficiency of 81.07% can be obtained under the conditions that the mass ratio of BaCO3 to CaO was 1:9 with the total proportion of the raw ore was 5 wt.%, the roasting temperature was 850°C, the roasting time was 2 h, the sulfuric acid concentration was 15% (v/v), the leaching temperature was 95°C, the liquid-to-solid ratio was 4 mL/g, and the leaching time was 3 h. Meanwhile, the vanadium leaching mechanisms demonstrated that the composite additive BaCO3/CaO can destroy the lattice structure of muscovite and phlogopite with the production of BaSi4O9 and Ca2Al2SiO7 during the roasting process, which can therefore facilitate the release and extraction of vanadium.

  17. Imaging of Vanadium in Microfossils: A New Potential Biosignature

    Science.gov (United States)

    Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.; Lai, Barry; Vogt, Stefan; Breuer, Pierre; Steemans, Philippe; Lay, Peter A.

    2017-11-01

    The inability to unambiguously distinguish the biogenicity of microfossil-like structures in the ancient rock record is a fundamental predicament facing Archean paleobiologists and astrobiologists. Therefore, novel methods for discriminating biological from nonbiological chemistries of microfossil-like structures are of the utmost importance in the search for evidence of early life on Earth. This, too, is important for the search for life on Mars by in situ analyses via rovers or sample return missions for future analysis here on Earth. Here, we report the application of synchrotron X-ray fluorescence imaging of vanadium, within thermally altered organic-walled microfossils of bona fide biological origin. From our data, we demonstrate that vanadium is present within microfossils of undisputable biological origin. It is well known in the organic geochemistry literature that elements such as vanadium are enriched and contained within crude oils, asphalts, and black shales that have been formed by diagenesis of biological organic material. It has been demonstrated that the origin of vanadium is due to the diagenetic alteration of precursor chlorophyll and heme porphyrin pigment compounds from living organisms. We propose that, taken together, microfossil-like morphology, carbonaceous composition, and the presence of vanadium could be used in tandem as a biosignature to ascertain the biogenicity of putative microfossil-like structures.

  18. Membrane development for vanadium redox flow batteries.

    Science.gov (United States)

    Schwenzer, Birgit; Zhang, Jianlu; Kim, Soowhan; Li, Liyu; Liu, Jun; Yang, Zhenguo

    2011-10-17

    Large-scale energy storage has become the main bottleneck for increasing the percentage of renewable energy in our electricity grids. Redox flow batteries are considered to be among the best options for electricity storage in the megawatt range and large demonstration systems have already been installed. Although the full technological potential of these systems has not been reached yet, currently the main problem hindering more widespread commercialization is the high cost of redox flow batteries. Nafion, as the preferred membrane material, is responsible for about 11% of the overall cost of a 1 MW/8 MWh system. Therefore, in recent years two main membrane related research threads have emerged: 1) chemical and physical modification of Nafion membranes to optimize their properties with regard to vanadium redox flow battery (VRFB) application; and 2) replacement of the Nafion membranes with different, less expensive materials. This review summarizes the underlying basic scientific issues associated with membrane use in VRFBs and presents an overview of membrane-related research approaches aimed at improving the efficiency of VRFBs and making the technology cost-competitive. Promising research strategies and materials are identified and suggestions are provided on how materials issues could be overcome.

  19. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

    DEFF Research Database (Denmark)

    Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham

    2016-01-01

    be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing......The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family......, the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must...

  20. Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

    Science.gov (United States)

    Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

    2018-01-01

    For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

  1. Cyclic degradation of titanium-tantalum high-temperature shape memory alloys - The role of dislocation activity and chemical decomposition

    OpenAIRE

    Niendorf, T.; Krooß, P.; Somsen, C.; Rynko, R.; Paulsen, A.; Batyrshina, E.; Frenzel, J.; G. Eggeler; Maier, Hans Jürgen

    2015-01-01

    Titanium-tantalum shape memory alloys (SMAs) are promising candidates for actuator applications at elevated temperatures. They may even succeed in substituting ternary nickel-titanium high temperature SMAs, which are either extremely expensive or difficult to form. However, titanium-tantalum alloys show rapid functional and structural degradation under cyclic thermo-mechanical loading. The current work reveals that degradation is not only governed by the evolution of the ω-phase. Dislocation ...

  2. Covalently grafted BMP-7 peptide to reduce macrophage/monocyte activity: an in vitro study on cobalt chromium alloy.

    Science.gov (United States)

    Tan, Hark Chuan; Poh, Chye Khoon; Cai, Yanli; Soe, Min Thun; Wang, Wilson

    2013-03-01

    Cobalt chromium (CoCr) alloy is widely used in orthopedic implants but its functional longevity is susceptible to inflammation related complications. Reduction of the development of chronic inflammation on the biomaterial surface would enhance direct bone-implant bonding and improve implant survival and long-term results. The BMP-7 peptide was derived from the knuckle epitope of bone morphogenic protein-7 (BMP-7) and was conjugated via a cysteine amino acid at the N-terminus. Mouse RAW 264.7 monocytes/macrophages were seeded on the CoCr substrates and inflammation was induced via lipopolysaccharide (LPS) challenge. The effects of BMP-7 peptide on inflammation were evaluated by measuring the expression of inflammatory markers like toll-like receptor-4 (TLR-4), tumor necrosis factor-α (TNF-α), and monocyte chemotactic protein-1 (MCP-1). ELISA and qPCR assays were used to study the inflammatory signals. BMP-7 signaling pathway activation was shown by the presence of phosphorylation of Smad1/5/8. Utilizing the reactivity of polydopamine films to immobilize BMP-7 peptide onto metal substrates may provide a promising approach for applications in situations where reduction of inflammation around implants would be beneficial in improving surgical outcome, bone healing, and implant integration. Copyright © 2012 Wiley Periodicals, Inc.

  3. Design and Control of a Proof-of-Concept Active Jet Engine Intake Using Shape Memory Alloy Actuators

    Science.gov (United States)

    Song, Gangbing; Ma, Ning; Penney, Nicholas; Barr, Todd; Lee, Ho-Jun; Arnold, Steven M.

    2004-01-01

    The design and control of a novel proof-of-concept active jet engine intake using Nickel-Titanium (Ni-Ti or Nitinol) shape memory alloy (SMA) wire actuators is used to demonstrate the potential of an adaptive intake to improve the fuel efficiency of a jet engine. The Nitinol SMA material is selected for this research due to the material's ability to generate large strains of up to 5 percent for repeated operations, a high power-to-weight ratio, electrical resistive actuation, and easy fabrication into a variety of shapes. The proof-of-concept engine intake employs an overlapping leaf design arranged in a concentric configuration. Each leaf is mounted on a supporting bar that rotates upon actuation by SMA wires electrical resistive heating. Feedback control is enabled through the use of a laser range sensor to detect the movement of a leaf and determine the radius of the intake area. Due to the hysteresis behavior inherent in SMAs, a nonlinear robust controller is used to direct the SMA wire actuation. The controller design utilizes the sliding-mode approach to compensate for the nonlinearities associated with the SMA actuator. Feedback control experiments conducted on a fabricated proof-of-concept model have demonstrated the capability to precisely control the intake area and achieve up to a 25 percent reduction in intake area. The experiments demonstrate the feasibility of engine intake area control using the proposed design.

  4. Mechanical characterization of Ti-12Mo-13Nb alloy for biomedical application hot swaged and aged

    Energy Technology Data Exchange (ETDEWEB)

    Gabriel, Sinara Borborema; Rezende, Monica Castro; Almeida, Luiz Henrique de, E-mail: sinara@metalmat.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Engenharia Metalurgica e de Materiais; Dille, Jean [Universite Libre de Bruxelles, Brussels (Belgium); Mei, Paulo [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Departamento de Engenharia Mecanica; Baldan, Renato; Nunes, Carlos Angelo [Universidade de Sao Paulo (USP), Lorena, SP (Brazil). Departamento de Engenharia de Materiais

    2015-07-01

    Beta titanium alloys were developed for biomedical applications due to the combination of its mechanical properties including low elasticity modulus, high strength, fatigue resistance, good ductility and with excellent corrosion resistance. With this perspective a metastable beta titanium alloy Ti-12Mo-13Nb was developed with the replacement of both vanadium and aluminum from the traditional alloy Ti-6Al-4V. This paper presents the microstructure, mechanical properties of the Ti-12Mo-13Nb hot swaged and aged at 500 deg C for 24 h under high vacuum and then water quenched. The alloy structure was characterized by X-ray diffraction and transmission electron microscopy. Tensile tests were carried out at room temperature. The results show a microstructure consisting of a fine dispersed α phase in a β matrix and good mechanical properties including low elastic modulus. The results indicate that Ti-12Mo-13Nb alloy can be a promising alternative for biomedical application. (author)

  5. Optical Characterization of AlAsSb Digital Alloy and Random Alloy on GaSb

    Directory of Open Access Journals (Sweden)

    Bor-Chau Juang

    2017-10-01

    Full Text Available III-(As, Sb alloys are building blocks for various advanced optoelectronic devices, but the growth of their ternary or quaternary materials are commonly limited by spontaneous formation of clusters and phase separations during alloying. Recently, digital alloy growth by molecular beam epitaxy has been widely adopted in preference to conventional random alloy growth because of the extra degree of control offered by the ordered alloying. In this article, we provide a comparative study of the optical characteristics of AlAsSb alloys grown lattice-matched to GaSb using both techniques. The sample grown by digital alloy technique showed stronger photoluminescence intensity, narrower peak linewidth, and larger carrier activation energy than the random alloy technique, indicating an improved optical quality with lower density of non-radiative recombination centers. In addition, a relatively long carrier lifetime was observed from the digital alloy sample, consistent with the results obtained from the photoluminescence study.

  6. Direct Acid Leaching of Vanadium from Stone Coal

    Science.gov (United States)

    Zhang, Bo; Gao, Zhaoguo; Liu, Hongzhao; Wang, Wei; Cao, Yaohua

    2017-09-01

    This paper focused on optimizing the process conditions of direct acid leaching process to enhance the leaching efficiency of leaching vanadium from the stone coal. Orthogonal experiments and single factor experiments were conducted to investigate the effect of the influential factors of direct acid leaching on vanadium leaching ratio. The results showed that the vanadium leaching ratio reached the maximum value of 89.22 % under the optimal process conditions of CaF2 dosage 5 mass%, H2SO4 dosage 40 mass%, leaching temperature 95 °C and leaching time 10 h. Furthermore, the reaction mechanisms of the main influencing factors were analyzed. Finally, the two-stage counter-current leaching process was adopted to decrease the consumption of sulfuric acid and neutralizer, and the results indicated that the consumption of sulfuric acid decreased 12.50 % as well as neutralizer decreased 35.80 %.

  7. Complex research of vanadium dioxide in the homoginuity field

    Science.gov (United States)

    Surikov, Vad I.; Semenyuk, N. A.; Surikov, Val I.; Kuznetsova, Y. V.; Pavlovskaya, O. Y.

    2018-01-01

    The complex research results of vanadium dioxide VÜ2±x obtained with X-ray analysis method, a method of vacuum adiabatic calorimeter and Faraday method are discussed. The samples temperature dependences of electrical resistivity, heat capacity, and also magnetic susceptibility are presented and they prove that these characteristics jump abruptly in the phase transition area. Thermophysical, electrical, magnetic properties of vanadium dioxide are established to vary with the oxygen content in the samples. Values of Debye characteristic temperatures θD for samples VO2±x determined at temperature 150 K are presented. Values of entropy change as an amount of electronic and phonon components at phase transition were calculated. The results obtained allow to consider the phase transition of a metal semiconductor as a Mott-Peierls transition, and also to use vanadium dioxide in temperature sensors manufacture.

  8. Vanadium-modified molecular sieves: preparation, characterization and catalysis

    Directory of Open Access Journals (Sweden)

    Ângela A. Teixeira-Neto

    2009-01-01

    Full Text Available Vanadium-containing molecular sieves are redox catalysts and are good candidates as substitutes for oxide-supported V2O5 in a number of reactions. These materials have the advantage of presenting better dispersion of vanadium species, as well as shape-selective properties and controllable acidities. They may be prepared by one-pot synthesis or by post-synthesis methods and a number of techniques such as diffuse reflectance UV-visible spectroscopy, 51V nuclear magnetic resonance and electron paramagnetic resonance, to name but a few, have been used to characterize these materials. In this review, methods of preparation of vanadium-modified molecular sieves, their characterization and applications in catalysis are discussed.

  9. The determination of vanadium in brines by atomic absorption spectroscopy

    Science.gov (United States)

    Crump-Wiesner, Hans J.; Feltz, H.R.; Purdy, W.C.

    1971-01-01

    A standard addition method is described for the determination of vanadium in brines by atomic absorption spectroscopy with a nitrous oxide-acetylene flame. Sample pH is adjusted to 1.0 with concentrated hydrochloric acid and the vanadium is directly extracted with 5% cupferron in methyl isobutyl ketone (MIBK). The ketone layer is then aspirated into the flame and the recorded absorption values are plotted as a function of the concentration of the added metal. As little as 2.5 ??g l-1 of vanadium can be detected under the conditions of the procedure. Tungsten and tin interfere when present in excess of 5 and 10 ??g ml-1, respectively. The concentrations of the two interfering ions normally found in brines are well below interference levels. ?? 1971.

  10. Evaluation of Botanical Reference Materials for the Determination of Vanadium in Biological Samples

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Damsgaard, Else

    1982-01-01

    Three botanical reference materials prepared by the National Bureau of Standards have been studied by neutron activation analysis to evaluate their suitability with respect to the determination of vanadium in biological samples. Various decomposition methods were applied in connection with chemic....... A reference value of 1.15 mg/kg of this material is recommended, based on results from 3 different methods. All three materials are preferable to SRM 1571 Orchard Leaves, while Bowen's Kale remains the material of choice because of its lower concentration....

  11. The black and white coatings on Ti-6Al-4V alloy or pure titanium by plasma electrolytic oxidation in concentrated silicate electrolyte

    Science.gov (United States)

    Han, Jun-xiang; Cheng, Yu-lin; Tu, Wen-bin; Zhan, Ting-Yan; Cheng, Ying-liang

    2018-01-01

    Black TiO2 has triggered scientific interest due to its unique properties such as enhanced solar-driven photocatalytic activity. In this paper, plasma electrolytic oxidation (PEO) treatment of Ti-6Al-4V alloy has been carried out in concentrated sodium silicate electrolyte. Silica-based black and white TiO2 coatings respectively have been obtained by controlling the oxidation time. The black coating, which was formed with a short treatment time, shows good corrosion resistance and the black appearance can be attributed to the presence of Ti2+ and Ti3+ in the coating. The lower valence titanium ions are absent in the white coatings and they also contain relatively higher Na content compared to the black coatings. The white coatings have great surface roughnesses and super hydrophilicity. The bonding strengths of the black and white coatings on the Ti-6Al-4V alloy are ∼14.4 and 4.3 MPa, respectively. The vanadium contributes little to the black appearance of the coating on Ti6Al4V alloy, since the same phenomena occur for the PEO of a pure titanium substrate.

  12. Three-dimensional Nitrogen-Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Engelhard, Mark H. [Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

    2017-02-22

    The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO2+/VO2+ redox couples. Therefore, it is vital to develop new electrocatalyst with enhanced activity to improve the battery performance. Herein, we first synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen-doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivey, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as-prepared composite presents enhanced catalytic performance toward the VO2+/VO2+ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.

  13. Catalytic and kinetic spectrophotometric method for determination of vanadium(V by 2,3,4-trihydroxyacetophenonephenylhydrazone

    Directory of Open Access Journals (Sweden)

    P.V. Chalapathi

    2014-12-01

    Full Text Available A new catalytic and kinetic spectrophotometric method for the determination of vanadium(V was studied using 2,3,4-trihydroxyacetophenonephenylhydrazone (THAPPH as an analytical reagent. The present method was developed on the catalytic effect of vanadium on oxidation of THAPPH by hydrogen peroxide in hydrochloric acid–potassium chloride buffer (pH = 2.8 at the 20th minute. The metal ion has formed 1:2 (M:L complex with THAPPH. Beer’s law was obeyed in the range 20–120 ng/mL of V(V at λmax 390 nm. The sensitivity of the method was calculated in terms of molar absorptivity (1.999 × 105 L mol−1cm−1 and Sandell’s sensitivity (0.000254 μg cm−2, shows that this method is more sensitive. The standard deviation (0.0022, relative standard deviation (0.56%, confidence limit (±0.0015 and standard error (0.0007 revealed that the developed method has more precision and accuracy. The stability constant was calculated with the help of Asmu’s (9.411 × 10−11 and Edmond’s & Birnbaum’s (9.504 × 10−11 methods at room temperature. The interfering effect of various cations and anions was also studied. The present method was successfully applied for the determination of vanadium(V in environmental and alloy samples. The method’s validity was checked by comparing the results obtained with atomic-absorption spectrophotometry and also by evaluation of results using F-test.

  14. Electrocatalytic oxidation of small organic molecules in acid medium: enhancement of activity of noble metal nanoparticles and their alloys by supporting or modifying them with metal oxides

    Science.gov (United States)

    Kulesza, Pawel J.; Pieta, Izabela S.; Rutkowska, Iwona A.; Wadas, Anna; Marks, Diana; Klak, Karolina; Stobinski, Leszek; Cox, James A.

    2013-01-01

    Different approaches to enhancement of electrocatalytic activity of noble metal nanoparticles during oxidation of small organic molecules (namely potential fuels for low-temperature fuel cells such as methanol, ethanol and formic acid) are described. A physical approach to the increase of activity of catalytic nanoparticles (e.g. platinum or palladium) involves nanostructuring to obtain highly dispersed systems of high surface area. Recently, the feasibility of enhancing activity of noble metal systems through the formation of bimetallic (e.g. PtRu, PtSn, and PdAu) or even more complex (e.g. PtRuW, PtRuSn) alloys has been demonstrated. In addition to possible changes in the electronic properties of alloys, specific interactions between metals as well as chemical reactivity of the added components have been postulated. We address and emphasize here the possibility of utilization of noble metal and alloyed nanoparticles supported on robust but reactive high surface area metal oxides (e.g. WO3, MoO3, TiO2, ZrO2, V2O5, and CeO2) in oxidative electrocatalysis. This paper concerns the way in which certain inorganic oxides and oxo species can act effectively as supports for noble metal nanoparticles or their alloys during electrocatalytic oxidation of hydrogen and representative organic fuels. Among important issues are possible changes in the morphology and dispersion, as well as specific interactions leading to the improved chemisorptive and catalytic properties in addition to the feasibility of long time operation of the discussed systems. PMID:24443590

  15. BRAZING ALLOYS

    Science.gov (United States)

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1962-02-20

    A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

  16. Vanadium and cadmium in vivo effects in teleost cardiac muscle: metal accumulation and oxidative stress markers.

    Science.gov (United States)

    Soares, S S; Martins, H; Gutiérrez-Merino, C; Aureliano, M

    2008-03-01

    Several biological studies associate vanadium and cadmium with the production of reactive oxygen species (ROS), leading to lipid peroxidation and antioxidant enzymes alterations. The present study aims to analyse and compare the oxidative stress responses induced by an acute intravenous exposure (1 and 7 days) to a sub-lethal concentration (5 mM) of two vanadium solutions, containing different vanadate n-oligomers (n=1-5 or n=10), and a cadmium solution on the cardiac muscle of the marine teleost Halobatrachus didactylus (Lusitanian toadfish). It was observed that vanadium is mainly accumulated in mitochondria (1.33+/-0.26 microM), primarily when this element was administrated as decameric vanadate, than when administrated as metavanadate (432+/-294 nM), while the highest content of cadmium was found in cytosol (365+/-231 nM). Indeed, decavanadate solution promotes stronger increases in mitochondrial antioxidant enzymes activities (catalase: +120%; superoxide dismutase: +140%) than metavanadate solution. On contrary, cadmium increases cytosolic catalase (+111%) and glutathione peroxidases (+50%) activities. It is also observed that vanadate oligomers induce in vitro prooxidant effects in toadfish heart, with stronger effects induced by metavanadate solution. In summary, vanadate and cadmium are differently accumulated in blood and cardiac subcellular fractions and induced different responses in enzymatic antioxidant defence mechanisms. In the present study, it is described for the first time the effects of equal doses of two different metals intravenously injected in the same fish species and upon the same exposure period allowing to understand the mechanisms of vanadate and cadmium toxicity in fish cardiac muscle.

  17. Adsorption kinetics and isotherm of vanadium with melamine.

    Science.gov (United States)

    Peng, Hao; Liu, Zuohua; Tao, Changyuan

    2017-05-01

    Melamine, possessing three free amino groups and three aromatic nitrogen atoms in its molecule, has great potential as an adsorbent for metal ions. We investigated three impact factors of the adsorption process: the initial pH of the vanadium solution, contact time and reaction temperature. The adsorption kinetics could be accurately described by the pseudo-second-order kinetic model. Langmuir and Freundlich models fitted well with the experimental equilibrium data, and the maximal adsorption capacity was found to be 1,428.57 mg vanadium/g melamine, and the Freundlich model showed the adsorption is privilege type.

  18. Tuning the activity of Pt alloy electrocatalysts by means of the lanthanide contraction

    DEFF Research Database (Denmark)

    Escribano, Maria Escudero; Malacrida, Paolo; Hansen, Martin Hangaard

    2016-01-01

    The high platinum loadings required to compensate for the slow kinetics of the oxygen reduction reaction (ORR) impede the widespread uptake of low-temperature fuel cells in automotive vehicles. We have studied the ORR on eight platinum (Pt)–lanthanide and Pt-alkaline earth electrodes, Pt5M, where M...... activity versus the bulk lattice parameter follows a high peaked “volcano” relation. We demonstrate how the lanthanide contraction can be used to control strain effects and tune the activity, stability, and reactivity of these materials....

  19. Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

    Directory of Open Access Journals (Sweden)

    Qiushi Zheng

    2017-02-01

    Full Text Available Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extraction of vanadium. Hence, the vanadium location is necessary for exploring the essence of vanadium extraction. Although most infer that vanadium may substitute for trivalent aluminium (Al as the isomorphism in muscovite for the similar atomic radius, there is not enough experimental evidence and theoretical supports to accurately locate the vanadium site in muscovite. In this study, the muscovite model and optimal location of vanadium were calculated by density functional theory (DFT. We find that the vanadium prefers to substitute for the hexa-coordinated aluminum of muscovite for less deformation and lower substitution energy. Furthermore, the local geometry and relative electronic properties were calculated in detail. The basal theoretical research of muscovite contained with vanadium are reported for the first time. It will make a further influence on the technology development of vanadium extraction from stone coal.

  20. Composition-dependent electrocatalytic activity of palladium-iridium binary alloy nanoparticles supported on the multiwalled carbon nanotubes for the electro-oxidation of formic acid.

    Science.gov (United States)

    Bao, Jianming; Dou, Meiling; Liu, Haijing; Wang, Feng; Liu, Jingjun; Li, Zhilin; Ji, Jing

    2015-07-22

    Surface-functionalized multiwalled carbon nanotubes (MWCNTs) supported Pd100-xIrx binary alloy nanoparticles (Pd100-xIrx/MWCNT) with tunable Pd/Ir atomic ratios were synthesized by a thermolytic process at varied ratios of bis(acetylacetonate) palladium(II) and iridium(III) 2,4-pentanedionate precursors and then applied as the electrocatalyst for the formic acid electro-oxidation. The X-ray diffraction pattern (XRD) and transmission electron microscope (TEM) analysis showed that the Pd100-xIrx alloy nanoparticles with the average size of 6.2 nm were uniformly dispersed on the MWCNTs and exhibited a single solid solution phase with a face-centered cubic structure. The electrocatalytic properties were evaluated through the cyclic voltammetry and chronoamperometry tests, and the results indicated that both the activity and stability of Pd100-xIrx/MWCNT were strongly dependent on the Pd/Ir atomic ratios: the best electrocatalytic performance in terms of onset potential, current density, and stability against CO poisoning was obtained for the Pd79Ir21/MWCNT. Moreover, compared with pure Pd nanoparticles supported on MWCNTs (Pd/MWCNT), the Pd79Ir21/MWCNT exhibited enhanced steady-state current density and higher stability, as well as maintained excellent electrocatalytic activity in high concentrated formic acid solution, which was attributed to the bifunctional effect through alloying Pd with transition metal.

  1. Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like shape for oxygen evolution reaction with enhanced catalytic activity

    Directory of Open Access Journals (Sweden)

    Tao Ding

    2016-01-01

    Full Text Available Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like wire shape has been achieved via a facile and moderate hydrothermal process at 120 °C for 1 h from the reaction of nickel nitrate and chloroplatinic acid in alkaline solution in the presence of ethanediamine and hydrazine hydrate. The holothuria-like alloyed NiPt wires are Ni-rich in composition (Ni23.6Pt and uniform in diameter with many tiny tips outstretched from the wires surface. The holothuria-like wires are assembled from granular subunits with the assistance of capping molecular of ethanediamine and the wires display an improved oxygen evolution reaction catalytic activity.

  2. Pitting corrosion resistance of a novel duplex alloy steel in alkali-activated slag extract in the presence of chloride ions

    Science.gov (United States)

    Shi, Jin-jie; Ming, Jing; Liu, Xin

    2017-10-01

    In this study, two types of reinforcing steels (conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions (ordinary Portland cement (OPC) extract and alkali-activated slag (AAS) extract) to investigate their pitting corrosion resistance. The results confirm that the pitting corrosion resistance of the alloy steel is much higher than that of the low-carbon steel in both extract solutions with various NaCl concentrations. Moreover, for each type of steel, the AAS extract contributes to a higher pitting corrosion resistance compared with the OPC extract in the presence of chloride ions, likely because of the formation of flocculent precipitates on the steel surface.

  3. Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

    Science.gov (United States)

    Jung, Myungwon; Mishra, Brajendra

    2017-11-01

    This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

  4. Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

    Science.gov (United States)

    Jung, Myungwon; Mishra, Brajendra

    2018-02-01

    This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

  5. Preparation and characterization of alloys of the Ti-15Mo-Nb system for biomedical applications.

    Science.gov (United States)

    Martins Júnior, J R S; Matos, A A; Oliveira, R C; Buzalaf, M A R; Costa, I; Rocha, L A; Grandini, C R

    2017-03-09

    In the development of new metallic biomaterials, the Ti-15Mo alloy has great prominence because of its excellent corrosion resistance and good combination of mechanical properties. In this study, the element niobium was added to the Ti-15Mo alloy, forming the Ti-15Mo-Nb system for the purpose of improving their properties and promoting its application as a biomaterial. These alloys are very promising to use as biomedical implants, because they integrate a new class of titanium alloys without the presence of aluminum and vanadium, which may cause cytotoxic effects. The alloys were produced by arc-melting and characterized by density, X-ray diffraction, scanning electron microscopy, microhardness, elastic modulus, corrosion, and cytotoxicity assays. The developed alloys have β phase predominance (with bcc crystalline structure). The addition of niobium decreases the microhardness and elastic modulus, with values around 80 GPa, which is well below that of the metallic alloys used commercially for this type of application. Very low passive current densities were found for all alloys studied showing that the passive film on these alloys is highly protective. In vitro cytotoxicity tests revealed that the introduction of niobium did not cause cytotoxic effects in the studied alloys. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  6. Design of new face-centered cubic high entropy alloys by thermodynamic calculation

    Science.gov (United States)

    Choi, Won-Mi; Jung, Seungmun; Jo, Yong Hee; Lee, Sunghak; Lee, Byeong-Joo

    2017-09-01

    A new face-centered cubic (fcc) high entropy alloy system with non-equiatomic compositions has been designed by utilizing a CALculation of PHAse Diagram (CALPHAD) - type thermodynamic calculation technique. The new alloy system is based on the representative fcc high entropy alloy, the Cantor alloy which is an equiatomic Co- Cr-Fe-Mn-Ni five-component alloy, but fully or partly replace the cobalt by vanadium and is of non-equiatomic compositions. Alloy compositions expected to have an fcc single-phase structure between 700 °C and melting temperatures are proposed. All the proposed alloys are experimentally confirmed to have the fcc single-phase during materials processes (> 800 °C), through an X-ray diffraction analysis. It is shown that there are more chances to find fcc single-phase high entropy alloys if paying attention to non-equiatomic composition regions and that the CALPHAD thermodynamic calculation can be an efficient tool for it. An alloy design technique based on thermodynamic calculation is demonstrated and the applicability and limitation of the approach as a design tool for high entropy alloys is discussed.

  7. On the layer structure of vanadium pentoxide gels. Comment on `molecular dynamic simulation of the vanadium pentoxide gel host`

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Takeshi [Department of Fundamental Energy Science, Graduate School of Energy Sciences, Kyoto University, Kyoto (Japan); Oka, Yoshio [Department of Natural Environment Sciences, Faculty of Integrated Human Studies, Kyoto University, Kyoto (Japan)

    1997-04-16

    A comment on the article entitled `molecular dynamic simulation of the vanadium pentoxide gel host` [J. Linde and J.O. Thomas, Solid State Ionics 85 (1996) 1] is presented concerning the model structure of the V{sub 2}O{sub 5} layer of vanadium pentoxide gels. The double-layer structure used in the simulation was derived from the crystalline V{sub 2}O{sub 5}. This model structure significantly differs from the double-sheet type determined by the X-ray Rietvelt method. The simulation should be recalculated based on the double-sheet type V{sub 2}O{sub 5} layer

  8. Technological Aspects of Low-Alloyed Cast Steel Massive Casting Manufacturing

    Directory of Open Access Journals (Sweden)

    Szajnara J.

    2013-12-01

    Full Text Available In the paper authors have undertaken the attempt of explaining the causes of cracks net occurrence on a massive 3-ton cast steel casting with complex geometry. Material used for casting manufacturing was the low-alloyed cast steel with increased wear resistance modified with vanadium and titanium. The studies included the primary and secondary crystallization analysis with use of TDA and the qualitative and quantitative analysis of non-metallic inclusions.

  9. Electrical Resistivity of Vanadium and Zirconium.

    Science.gov (United States)

    1982-12-01

    Purdue Univ., 2595 Yeager RA., W. Lafayette,IN 47906 11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Defense Technical Information Center...D.S.. ’Electrical Resistivity of Zircon ’- ium Alloys,’ UShIC Rept. 0SI-4370, 23-4 (1968). 61 136. Clinard, F.I., Jr. and Kempter, C.P., ’Low...Hake, 1.1., ’Localized Magnetic Impurity States in Titan- inm, Zirconium, and Hafnium .’ Phys. Rev. A. M,)(l), 142-9 (1965). 138. Powell, R.W. and Tye

  10. Oxygen Electroreduction Activity and X-Ray Photoelectron Spectroscopy of Platinum and Early Transition Metal Alloys

    DEFF Research Database (Denmark)

    Stephens, Ifan; Bondarenko, Alexander S.; Bech, Lone

    2012-01-01

    The oxygen reduction reaction (ORR) was studied experimentally on sputter-cleaned, polycrystalline electrodes of Pt3Y, Pt5Y, Pt2Y, Pt3Sc, Pt3Hf, Pt3Zr and Pt under conditions relevant for low-temperature fuel cells. The surfaces were characterised insitu by means of electrochemical methods...... and exsitu under ultrahigh vacuum conditions. The ORR activity was established in an electrochemical cell containing 0.1M HClO4 by use of a rotating ring disk electrode assembly. The surface composition was characterised before and after the electrochemical measurements by using angle-resolved X...

  11. Acoustic emission monitoring of activation behavior of LaNi5 hydrogen storage alloy

    Directory of Open Access Journals (Sweden)

    Igor Maria De Rosa, Alessandro Dell'Era, Mauro Pasquali, Carlo Santulli and Fabrizio Sarasini

    2011-01-01

    Full Text Available The acoustic emission technique is proposed for assessing the irreversible phenomena occurring during hydrogen absorption/desorption cycling in LaNi5. In particular, we have studied, through a parametric analysis of in situ detected signals, the correlation between acoustic emission (AE parameters and the processes occurring during the activation of an intermetallic compound. Decreases in the number and amplitude of AE signals suggest that pulverization due to hydrogen loading involves progressively smaller volumes of material as the number of cycles increases. This conclusion is confirmed by electron microscopy observations and particle size distribution measurements.

  12. Microstructure formations in copper-silicon carbide composites during mechanical alloying in a planetary activator

    Energy Technology Data Exchange (ETDEWEB)

    Kudashov, D.V.; Aksenov, A.A.; Portnoy, V.K.; Zolotorevskii, V.S. [Moscow State Inst. of Steel and Alloys, Moscow (Russian Federation). Dept. of Physical Metallurgy of Non-ferrous Metals; Klemm, V.; Martin, U.; Oettel, H. [Technical Univ., Freiberg (Germany). Inst. of Physical Metallurgy

    2000-12-01

    In the present paper the structure formation process of the powder metallurgical produced copper composite materials was studied. The volume part of the reinforcing SiC particles was varied from 5 to 25 wt.-%. It was discovered that while milling in a planetary activator first of all a ''puff- pastry'' structure appeared. There are important differences between this structure formation process and other known processes of milling. The homogeneous distribution of SiC particles was obtained after 60-100 minutes of treatment in ''Gefest11-3'' planetary activator. Phase composition of the powder and composite samples at the interface SiC/Cu (particles/matrix) was analysed after consolidation of the powder mixture and after the high temperature annealing. It was still determined that not only pure copper powder can be as a starting material for Cu-composites production used, but also the wastes of copper mechanical treatment, for instance, copper shaving. (orig.)

  13. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  14. Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

    2012-08-16

    Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT.

  15. Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity.

    Science.gov (United States)

    Saugo, M; Flamini, D O; Brugnoni, L I; Saidman, S B

    2015-11-01

    The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree. The highest amount of silver was deposited when the coated electrode was prepolarised at -1.00V (SCE) before silver deposition, suggesting an increase in the amount of non-oxidised segments in the polymer. Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. aureus. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Novel hybrid materials based on the vanadium oxide nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Zabrodina, G.S., E-mail: kudgs@mail.ru [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Makarov, S.G.; Kremlev, K.V. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Yunin, P.A.; Gusev, S.A. [Institute for Physics of Microstructures Russian Academy of Sciences, Nizhny Novgorod 603087 (Russian Federation); Kaverin, B.S.; Kaverina, L.B. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Ketkov, S.Yu. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation)

    2016-04-15

    Graphical abstract: - Highlights: • Flat and curved vanadium oxide nanobelts have been synthesized. • Hybrid material was prepared via decoration of flexible nanobelts with zinc phthalocyanine. • Investigations of the thermal stability, morphologies and structures were carried out. - Abstract: Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V{sub 2}O{sub 5}·nH{sub 2}O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB – cetyltrimethylammonium bromide, TBAB – tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA){sub 0.33}V{sub 2}O{sub 5} flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA){sub 0.33}V{sub 2}O{sub 5}, (TBA){sub 0.16}V{sub 2}O{sub 5} nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

  17. Structural and catalytic properties of a novel vanadium containing ...

    Indian Academy of Sciences (India)

    Abstract. A novel vanadium containing solid core mesoporous silica shell catalyst was synthesized with different Si/V ratios by sol-gel method under neutral conditions. The synthesized materials were characterized by various techniques and gas phase diphenyl methane oxidation reaction. The mesoporosity combined with ...

  18. Halofunctionalization of alkenes by vanadium chloroperoxidase from Curvularia inaequalis

    NARCIS (Netherlands)

    Dong, J.; Fernandez Fueyo, E.; Li, Jingbo; Guo, Zheng; Renirie, Rokus; Wever, Ron; Hollmann, F.

    The vanadium-dependent chloroperoxidase from Curvularia inaequalis is a stable and efficient biocatalyst for the hydroxyhalogenation of a broad range of alkenes into halohydrins. Up to 1 200 000 TON with 69 s−1 TOF were observed for the biocatalyst. A bienzymatic cascade to yield epoxides as

  19. Combined effect of vanadium and nickel on lipid peroxidation and ...

    African Journals Online (AJOL)

    In this investigation, hepatorenal antioxidant effects of combined oral administration of ammonium metavanadate (AMV; 0.15 mg V/ml) and nickel sulfate (NS; 0.18 mg Ni/ml) in male albino rats over a 21- day period have been evaluated. After administration of vanadium, lipid peroxidation (LPO) increased significantly (p ...

  20. TWO LIGAND OXIDIO-VANADIUM(IV) COMPLEXES AS NOVEL ...

    African Journals Online (AJOL)

    TWO LIGAND OXIDIO-VANADIUM(IV) COMPLEXES AS NOVEL EFFICIENT. CATALYSTS IN MULTICOMPONENT REACTIONS FOR SYNTHESIS OF. TETRAHYDROBENZOPYRAN DERIVATIVES. Mehdi Abaszadeh1,2*, Mohammad Seifi3 and S. Yousef Ebrahimipour 4,5. 1Pharmaceutics Research Center, Institute of ...

  1. Electrochemical properties of dip-coated vanadium pentaoxide thin ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 6. Electrochemical properties of dip-coated vanadium pentaoxide thin films. R S INGOLE B J LOKHANDE. Volume 39 Issue 6 ... Author Affiliations. R S INGOLE1 B J LOKHANDE1. School of Physical Sciences, Solapur University, Solapur 413 255, India ...

  2. Excimer laser reactive deposition of vanadium nitride thin films

    Science.gov (United States)

    D'Anna, E.; Di Cristoforo, A.; Fernández, M.; Leggieri, G.; Luches, A.; Majni, G.; Mengucci, P.; Nanai, L.

    2002-01-01

    We report on the deposition of thin vanadium nitride films by ablating vanadium targets in low-pressure N 2 atmosphere, and on their characterization. The targets were vanadium foils (purity 99.8%). 3 in. Si(1 1 1) wafers were used as substrates. Film characteristics (composition and crystalline structure) were studied as a function of N 2 pressure (0.5-200 Pa), KrF laser fluence (4.5-19 J/cm 2), substrate temperature (20-750 °C) and target-to-substrate distance (30-70 mm). Vanadium nitride is already formed at low N 2 ambient pressures (1 Pa) and laser fluences (6 J/cm 2) on substrates at room temperature. At the N 2 pressures of 1-10 Pa, the prevalent phase is VN. At higher pressures (100 Pa) and at relatively high laser fluences (16-19 J/cm 2), the dominant phase is V 2N. The crystallinity of the films improves by increasing the substrate temperature. Well-crystallized films are obtained on substrates heated at 500 °C.

  3. A model approach to vanadium involvement in crude oil refining

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    The research during the last nine months has continued with the overall goal of developing V/S chemistry and has been concentrated on the two main areas of the project: the reactivity chemistry of vanadyl complexes, and the development of sulfide-bridged vanadium cluster chemistry. Significant new progress has been achieved in both these areas.

  4. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3() ZnO(40-)V2O5(60) (where = 0.1–0.5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been calculated.

  5. Geochemical behaviour of vanadium in iron—titanium oxides

    NARCIS (Netherlands)

    Schuiling, R.D.; Feenstra, A.

    The following geochemical rules-of-thumb seem to hold for vanadium: 1. (1) Magnetites as a group have higher V contents than either hematites or ilmenites. 2. (2) In magnetite—hematite pairs, however, the hematite has the higher V content. 3. (3) In magnetite—ilmenite pairs, the magnetite

  6. Vanadium Effect on a Medium Carbon Forging Steel

    Directory of Open Access Journals (Sweden)

    Carlos Garcia-Mateo

    2016-05-01

    Full Text Available In the present work the influence of vanadium on the hardenability and the bainitic transformation of a medium carbon steel is analyzed. While V in solid solution enhances the former, it hardly affects bainitic transformation. The results also reveal an unexpected result, an increase of the prior austenite grain size as the V content increases.

  7. determination of vanadium in foods by atomic absorption spectrometry

    African Journals Online (AJOL)

    This paper presents an assessment of the level of vanadium in foods (Plantain, Musa spp; Yam, Discorea rotundata; and Maize, Zea mays) from ten popular market places in Lagos metropolis, Nigeria. Total acid leaching digestion method was employed and determination was by Flame Atomic Absorption ...

  8. Effects of Vanadium Pentoxide on the Histological and Sperm ...

    African Journals Online (AJOL)

    The pharmacological effects of intraperitoneal administration of different doses of vanadium pentoxide (V2O5) on the histological and sperm parameters of male guinea pigs were investigated. Also investigated were the effects of oral pretreatment with different doses of vitamin E (a known protein kinase C inhibitor) on the ...

  9. Partial Oxidation of n-Pentane over Vanadium Phosphorus Oxide ...

    African Journals Online (AJOL)

    The selective oxidation of n-pentane to value-added products, maleic anhydride or phthallic anhydride by vanadium phosphorus oxide loaded on hydroxyapatites as catalysts and oxygen as oxidant was investigated. Hydroxyapatite (HAp) and cobalthydroxyapatite (Co-HAp) were prepared by the co-precipitation method ...

  10. Role of vanadium in Keggin heteropoly molybdate supported on ...

    Indian Academy of Sciences (India)

    ated for oxidation of 1,2-benzenedimethanol using H2O2 and O2 as oxidants. .... C on oil bath. In the case of O2 as oxidant, reaction was conducted under O2 atmosphere. Progress of the reaction was monitored by using thin-layer chro- ... The role of vanadium in heteropoly molybdate catalysts for oxidation reactions. 469.

  11. Speciation of Chromium and Vanadium in Medicinal Plants

    African Journals Online (AJOL)

    NICOLAAS

    Results of the determination of water-soluble (hot water) Cr(VI) and V(V) concentrations ... tive and purging gas. 2.2. Quality Assurance. The analytical results for the determination of chromium and vanadium were validated through the analysis of certified refer- ... were filtered through 0.45 µm hydrophilic PVDF filter prior the.

  12. Organometalic carbosilane polymers containing vanadium and their preparation

    Science.gov (United States)

    Yajima, S.; Okamura, K.; Shishido, T.; Fukuda, K.

    1983-01-01

    The present invention concerns a new organometallic polymer material containing in part a vanadium-siloxane linkage (V-0-Si), which has excellent resistance to heat and oxidation and a high residue ratio after high temperature treatment in a non-oxidizing atmosphere, for example, nitrogen, argon, helium, ammonia, or hydrogen.

  13. Novel vanadium phosphate phases as catalysts for selective oxidation

    Indian Academy of Sciences (India)

    Unknown

    important vanadium phosphate phases used as selective oxidation catalysts, it has been observed that ... molybdenum oxides are the most widely used ones for the selective oxidation of alkanes. Amongst these the ... pentane to maleic and pthalic anhydride, and in the oxidative dehydrogenation of ethane, propane etc 4.

  14. Isolation and characterization of vanadium bromoperoxidase from a marine macroalga, Ecklonia stolonifera.

    Science.gov (United States)

    Hara, I; Sakurai, T

    1998-10-01

    The bromoperoxidase has been isolated from the marine brown alga, Ecklonia stolonifera (83 kDa) and has been characterized. Bromoperoxidase requires vanadium for enzyme activity as has been evidenced by EPR spectroscopy. The enzyme activity increased ca. 250% with the action of V5+ on the isolated enzyme, since more than 2/3 of the protein molecules were in the apo form. The increase in the enzyme activity was specific to V5+, while Fe2+, Fe3+, and Cu2+ inhibited the enzyme activity. This effect of V5+ addition was inhibited in phosphate buffer, probably because phosphate and vanadate compete for the active site. The bromoperoxidase exhibited a high thermostability (Tm = 68 degrees C) and a high stability in organic solvents (completely intact even in the presence of 50% methanol, ethanol and 1-propanol).

  15. Oxide composite prepared from intermetallic and amorphous Zr67Fe30M3- (M=Au, Pt) alloys and their catalytic activity for CO oxidation

    Science.gov (United States)

    Huang, Yung-Han; Wang, Sea-Fue; Kameoka, Satoshi; Miyamoto, Kanji; Tsai, An-Pang

    2017-01-01

    In this study, Zr67Fe30M3 (M=Au, Pt) intermetallic compounds and amorphous alloys were prepared and used as precursors for the synthesis of oxides. Oxidation treatment of the intermetallic compounds at 500 °C followed by X-ray diffraction (XRD) analysis indicated that zirconium and iron were oxidized to ZrO2 and Fe2O3, respectively. In the case of Zr67Fe30M3 amorphous alloys, cubic Zr6Fe3O was observed on the surface of the ribbons after heat treatment at 500 °C in vacuum. Addition of 3% of gold or platinum to the alloy resulted in an increase in the lattice constants of the Zr6Fe3O phase. Grounding the treated ribbons into powders followed by an oxidation treatment at 500 °C in air produced Fe2O3 and ZrO2 supports, where Au and Pt are dissolved in the oxides as confirmed by X-ray photoelectron spectroscopy (XPS). No matter precursors are intermetallics or amorphous phases, the resultant oxides are the same. Although Pt and Au dissolved in the oxides, catalytic activities for CO oxidation were significant improved.

  16. The ternary system: silicon-uranium-vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Noel, Henri [Laboratoire de Chimie du Solide et Materiaux, UMR-CNRS 6226, Universite de Rennes I, Avenue du General Leclerc, F-35042 Rennes, Cedex (France); Rogl, Peter Franz, E-mail: peter.franz.rogl@univie.ac.a [Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Waehringerstrasse 42 (Austria)

    2010-09-01

    Phase equilibria in the system Si-U-V were established at 1100 {sup o}C by optical microscopy, EMPA and X-ray diffraction. Two ternary compounds were observed, U{sub 2}V{sub 3}Si{sub 4} and (U{sub 1-x}V{sub x}){sub 5}Si{sub 3}, for which the crystal structures were elucidated by X-ray powder data refinement and found to be isotypic with the monoclinic U{sub 2}Mo{sub 3}Si{sub 4}-type (space group P2{sub 1}/c; a = 0.6821(3), b = 0.6820(4), c = 0.6735(3) nm, {beta} = 109.77(1){sup o}) and the tetragonal W{sub 5}Si{sub 3}-type (space group I4/mcm, a = 1.06825(2), c = 0.52764(2) nm), respectively. (U{sub 1-x}V{sub x}){sub 5}Si{sub 3} appears at 1100 {sup o}C without any significant homogeneity region at x {approx} 0.2 resulting in a formula U{sub 4}VSi{sub 3} which corresponds to a fully ordered atom arrangement. DTA experiments clearly show decomposition of this phase above 1206 {sup o}C revealing a two-phase region U{sub 3}Si{sub 2} + V{sub 3}Si. At 1100 {sup o}C U{sub 4}VSi{sub 3} is in equilibrium with V{sub 3}Si, V{sub 5}Si{sub 3}, U{sub 3}Si{sub 2} and U(V). At 800 {sup o}C U{sub 4}VSi{sub 3} forms one vertex of the tie-triangle to U{sub 3}Si and V{sub 3}Si. Due to the rather high thermodynamic stability of V{sub 3}Si and the corresponding tie-lines V{sub 3}Si + liquid at 1100 {sup o}C and V{sub 3}Si + U(V) below 925 {sup o}C, no compatibility exists between U{sub 3}Si or U{sub 3}Si{sub 2} and vanadium metal.

  17. Vanadium bromoperoxidase-catalyzed biosynthesis of halogenated marine natural products.

    Science.gov (United States)

    Carter-Franklin, Jayme N; Butler, Alison

    2004-11-24

    Marine red algae (Rhodophyta) are a rich source of bioactive halogenated natural products. The biogenesis of the cyclic halogenated terpene marine natural products, in particular, has attracted sustained interest in part because terpenes are the biogenic precursors of many bioactive metabolites. The first enzymatic asymmetric bromination and cyclization of a terpene, producing marine natural products isolated from red algae, is reported. Vanadium bromoperoxidase (V-BrPO) isolated from marine red algae (species of Laurencia, Plocamium, Corallina) catalyzes the bromination of the sesquiterpene (E)-(+)-nerolidol producing alpha-, beta-, and gamma-snyderol and (+)-3beta-bromo-8-epicaparrapi oxide. alpha-Snyderol, beta-snyderol, and (+)-3beta-bromo-8-epicaparrapi oxide have been isolated from Laurencia obtusa, and each have also been isolated from other species of marine red algae. gamma-Snyderol is a proposed intermediate in other bicyclo natural products. Single diastereomers of beta-snyderol, gamma-snyderol, and mixed diastereomers of (+)-3beta-bromo-8-epicaparrapi oxide (de = 20-25%) are produced in the enzyme reaction, whereas two diastereomers of these compounds are formed in the synthesis with 2,4,4,6-tetrabromocyclohexa-2,5-dienone (TBCO). V-BrPO likely functions by catalyzing the two-electron oxidation of bromide ion by hydrogen peroxide producing a bromonium ion or equivalent in the active site that brominates one face of the terminal olefin of nerolidol. These results establish V-BrPO's role in the biosynthesis of brominated cyclic sesquiterpene structures from marine red algae for the first time.

  18. The effects of surface modification on carbon felt electrodes for use in vanadium redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Jae; Kim, Young-Jun; Kim, Jae-Hun [Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816 (Korea, Republic of); Park, Min-Sik, E-mail: parkms@keti.re.kr [Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816 (Korea, Republic of)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We observed the physical and chemical changes on the surface of carbon felts after various surface modifications. Black-Right-Pointing-Pointer The surface area and chemistry of functional groups formed on the surface of carbon felt are critical to determine the kinetics of the redox reactions of vanadium ions. Black-Right-Pointing-Pointer By incorporation of the surface modifications into the electrode preparation, the electrochemical activity of carbon felts could be notably enhanced. - Abstract: The surface of carbon felt electrodes has been modified for improving energy efficiency of vanadium redox flow batteries. For comparative purposes, the effects of various surface modifications such as mild oxidation, plasma treatment, and gamma-ray irradiation on the electrochemical properties of carbon felt electrodes were investigated at optimized conditions. The cell energy efficiency was improved from 68 to 75% after the mild oxidation of the carbon felt at 500 Degree-Sign C for 5 h. This efficiency improvement could be attributed to the increased surface area of the carbon felt electrode and the formation of functional groups on its surface as a result of the modification. On the basis of various structural and electrochemical characterizations, a relationship between the surface nature and electrochemical activity of the carbon felt electrodes is discussed.

  19. Crossing points in the electronic band structure of vanadium oxide

    Directory of Open Access Journals (Sweden)

    Keshav N. Shrivastava

    2010-03-01

    Full Text Available The electronic band structures of several models of vanadium oxide are calculated. In the models 1-3, every vanadium atom is connected to 4 oxygen atoms and every oxygen atom is connected to 4 vanadium atoms. In model 1, a=b=c 2.3574 Å; in model 2, a= 4.7148 Å, b= 2.3574 Å and c= 2.3574 Å; and in model 3, a= 4.7148 Å, b= 2.3574 Å and c= 4.7148 Å. In the models 4-6, every vanadium atom is connected to 4 oxygen atoms and every oxygen atom is connected to 2 vanadium atoms. In model 4, a=b= 4.551 Å and c= 2.851 Å; in model 5, a=b=c= 3.468 Å; and in model 6, a=b=c= 3.171 Å. We have searched for a crossing point in the band structure of all the models. In model 1 there is a point at which five bands appear to meet but the gap is 7.3 meV. In model 2 there is a crossing point between G and F points and there is a point between F and Q with the gap ≈ 3.6608 meV. In model 3, the gap is very small, ~ 10-5 eV. In model 4, the gap is 5.25 meV. In model 5, the gap between Z and G points is 2.035 meV, and in model 6 the gap at Z point is 4.3175 meV. The crossing point in model 2 looks like one line is bent so that the supersymmetry is broken. When pseudopotentials are replaced by a full band calculation, the crossing point changes into a gap of 2.72 x 10-4 eV.

  20. A novel comprehensive utilization of vanadium slag: As gamma ray shielding material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Mengge [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Xue, Xiangxin, E-mail: xuexx@mail.neu.edu.cn [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Yang, He; Liu, Dong [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Wang, Chao [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Zhefu [Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-11-15

    Highlights: • A novel comprehensive utilization method for vanadium slag is proposed. • Shielding properties of vanadium slag are better than ordinary concrete. • HVL of vanadium slag is between Lead and concrete to shield {sup 60}Co gamma ray. • HVL of composite is higher than concrete when adding amount of vanadium slag is 900. • Composite can be used as injecting mortar for cracks developed in concrete shields. - Abstract: New exploration of vanadium slag as gamma ray shielding material was proposed, the shielding properties of vanadium slag was higher than concrete when the energy of photons was in 0.0001 MeV–100000 MeV. Vanadium slag/epoxy resin composites were prepared, shielding and material properties of materials were tested by {sup 60}Co gamma ray, simultaneous DSC-TGA, electronic universal testing machine and scanning electron microscopy, respectively. The results showed that the shielding properties of composite would be better with the increase of vanadium slag addition amount. The HVL (half value layer thickness) of vanadium slag was between Lead and concrete while composite was higher than concrete when the addition amount of vanadium slag was 900 used as material to shield {sup 60}Co gamma ray, also the resistance temperature of composite was about 215 °C and the bending strength was over 10 MPa. The composites could be used as injecting mortar for cracks developed in biological concrete shields, coating for the floor of the nuclear facilities, and shielding materials by itself.

  1. Orthodontic silver brazing alloys.

    Science.gov (United States)

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy.

  2. Aluminum Alloy and Article Cast Therefrom

    Science.gov (United States)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

  3. The role of phosphate additive in stabilization of sulphuric-acid-based vanadium(V) electrolyte for all-vanadium redox-flow batteries

    Science.gov (United States)

    Roznyatovskaya, Nataliya V.; Roznyatovsky, Vitaly A.; Höhne, Carl-Christoph; Fühl, Matthias; Gerber, Tobias; Küttinger, Michael; Noack, Jens; Fischer, Peter; Pinkwart, Karsten; Tübke, Jens

    2017-09-01

    Catholyte in all-vanadium redox-flow battery (VRFB) which consists of vanadium salts dissolved in sulphuric acid is known to be stabilized by phosphoric acid to slow down the thermal aging at temperatures higher than 40 °C. To reveal the role of phosphoric acid, the thermally-induced aggregation is investigated using variable-temperature 51V, 31P, 17O, 1H nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS). The results indicate that the thermal stabilization of vanadium(V) electrolyte is attained by the involvement of monomeric and dimeric vanadium(V) species in the reaction with phosphoric acid which is concurrent to the formation of neutral hydroxo-aqua vanadium(V) precipitation precursor. The dimers are stabilized by counter ions due to association reaction or if such stabilization is not possible, precipitation of vanadium pentoxide is favored. The evolution of particles size distributions at 50 °C in electrolyte samples containing 1.6 M vanadium and 4.0 M total sulphate and the pathways of precipitate formation are discussed. The optimal total phosphate concentration is found to be of 0.15 M. However, the induction time is assumed to be dependent not only on the total phosphate concentrations, but also on the ratio of total vanadium(V) to sulphate concentrations.

  4. Thermodynamics and kinetics of reactions involving vanadium in natural systems: Accumulation of vanadium in sedimentary rocks

    Science.gov (United States)

    Wanty, R.B.; Goldhaber, M.B.

    1992-01-01

    A critical review of thermodynamic data for aqueous and solid V species is presented to evaluate dissolution, transport, and precipitation of V under natural conditions. Emphasis is given to results of experimental studies of V chemistry, especially those for which the experimental conditions are near those found in nature. Where possible, data are obtained for or corrected to the reference conditions of 298.15K, 1 atm (1.01325 bar) and zero ionic strength. Vanadium [IV] (VIV) and vanadium[V] (VV) are the most soluble forms of V in nature, and their complexes with fluoride, sulfate, and oxalate may act to increase V solubility under oxidizing conditions. Because redox behavior is of fundamental importance to understanding natural V chemistry, the kinetics of reduction of VIV to VIII H2S were studied. Although H2S is predicted from thermodynamic data to be capable of reducing VIV to VIII, this reaction has not been demonstrated experimentally. Experiments were carried out under conditions of temperature (45??C), pH (3.6-6.8), ionic strength (0.05-0.1 m), and V concentrations (9.8-240 ??molar) likely to be found in nature. Because the reaction is very slow, H2S concentrations in excess of natural conditions were used (8.1 ?? 10-4 to 0.41 atm). The results show that VIV is reduced to VIII under a variety of conditions. The rate increases with increasing pH, but is not appreciably affected by ionic strength (as represented by the concentration of KCl, which was used as the supporting electrolyte in all cases). Prior to initiation of the reaction, there is an induction period, the length of which increases with increasing KCl concentration or decreasing pH. Attempts to model the reaction mechanism by numerical methods have failed to produce a satisfying fit of the results, indicating partial reaction orders, a complex mechanism, or involvement of a variety of intermediate species. The results of the thermodynamic and kinetic studies were applied to understanding the

  5. High-strength, low-alloy steels.

    Science.gov (United States)

    Rashid, M S

    1980-05-23

    High-strength, low-alloy (HSLA) steels have nearly the same composition as plain carbon steels. However, they are up to twice as strong and their greater load-bearing capacity allows engineering use in lighter sections. Their high strength is derived from a combination of grain refinement; precipitation strengthening due to minor additions of vanadium, niobium, or titanium; and modifications of manufacturing processes, such as controlled rolling and controlled cooling of otherwise essentially plain carbon steel. HSLA steels are less formable than lower strength steels, but dualphase steels, which evolved from HSLA steels, have ferrite-martensite microstructures and better formability than HSLA steels of similar strength. This improved formability has substantially increased the utilization potential of high-strength steels in the manufacture of complex components. This article reviews the development of HSLA and dual-phase steels and discusses the effects of variations in microstructure and chemistry on their mechanical properties.

  6. A novel process for the recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite: sodium modification-direct reduction coupled process

    Science.gov (United States)

    Zhang, Yi-min; Yi, Ling-yun; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

    2017-05-01

    A sodium modification-direct reduction coupled process was proposed for the simultaneous extraction of V and Fe from vanadium- bearing titanomagnetite. The sodium oxidation of vanadium oxides to water-soluble sodium vanadate and the transformation of iron oxides to metallic iron were accomplished in a single-step high-temperature process. The increase in roasting temperature favors the reduction of iron oxides but disfavors the oxidation of vanadium oxides. The recoveries of vanadium, iron, and titanium reached 84.52%, 89.37%, and 95.59%, respectively. Moreover, the acid decomposition efficiency of titanium slag reached 96.45%. Compared with traditional processes, the novel process provides several advantages, including a shorter flow, a lower energy consumption, and a higher utilization efficiency of vanadium-bearing titanomagnetite resources.

  7. The Vanadium Iodoperoxidase from the marine flavobacteriaceae species Zobellia galactanivorans reveals novel molecular and evolutionary features of halide specificity in the vanadium haloperoxidase enzyme family.

    Science.gov (United States)

    Fournier, Jean-Baptiste; Rebuffet, Etienne; Delage, Ludovic; Grijol, Romain; Meslet-Cladière, Laurence; Rzonca, Justyna; Potin, Philippe; Michel, Gurvan; Czjzek, Mirjam; Leblanc, Catherine

    2014-12-01

    Vanadium haloperoxidases (VHPO) are key enzymes that oxidize halides and are involved in the biosynthesis of organo-halogens. Until now, only chloroperoxidases (VCPO) and bromoperoxidases (VBPO) have been characterized structurally, mainly from eukaryotic species. Three putative VHPO genes were predicted in the genome of the flavobacterium Zobellia galactanivorans, a marine bacterium associated with macroalgae. In a phylogenetic analysis, these putative bacterial VHPO were closely related to other VHPO from diverse bacterial phyla but clustered independently from eukaryotic algal VBPO and fungal VCPO. Two of these bacterial VHPO, heterogeneously produced in Escherichia coli, were found to be strictly specific for iodide oxidation. The crystal structure of one of these vanadium-dependent iodoperoxidases, Zg-VIPO1, was solved by multiwavelength anomalous diffraction at 1.8 Å, revealing a monomeric structure mainly folded into α-helices. This three-dimensional structure is relatively similar to those of VCPO of the fungus Curvularia inaequalis and of Streptomyces sp. and is superimposable onto the dimeric structure of algal VBPO. Surprisingly, the vanadate binding site of Zg-VIPO1 is strictly conserved with the fungal VCPO active site. Using site-directed mutagenesis, we showed that specific amino acids and the associated hydrogen bonding network around the vanadate center are essential for the catalytic properties and also the iodide specificity of Zg-VIPO1. Altogether, phylogeny and structure-function data support the finding that iodoperoxidase activities evolved independently in bacterial and algal lineages, and this sheds light on the evolution of the VHPO enzyme family. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  8. New Mechanism for the Reduction of Vanadyl Acetylacetonate to Vanadium Acetylacetonate for Room Temperature Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shamie, Jack S. [Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago Illinois 60616 USA; Liu, Caihong [Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago Illinois 60616 USA; Shaw, Leon L. [Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago Illinois 60616 USA; Sprenkle, Vincent L. [Energy Storage and Conversion Energy Materials, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2016-12-29

    In this study, a new mechanism for the reduction of vanadyl acetylacetonate, VO(acac)2, to vanadium acetylacetonate, V(acac)3, is introduced. V(acac)3 has been studied for use in redox flow batteries (RFBs) for some time; however, contamination by moisture leads to the formation of VO(acac)2. In previous work, once this transformation occurs, it is no longer reversible because there is a requirement for extreme low potentials for the reduction to occur. Here, we propose that, in the presence of excess acetylacetone (Hacac) and free protons (H+), the reduction can take place between 2.25 and 1.5 V versus Na/Na+ via a one-electron-transfer reduction. This reduction can take place in situ during discharge in a novel hybrid Na-based flow battery (HNFB) with a molten Na–Cs alloy as the anode. The in situ recovery of V(acac)3 during discharge is shown to allow the Coulombic efficiency of the HNFB to be ≈100 % with little or no capacity decay over cycles. In addition, utilizing two-electron-transfer redox reactions (i.e., V3+/V4+ and V2+/V3+ redox couples) per V ion to increase the energy density of RFBs becomes possible owing to the in situ recovery of V(acac)3 during discharge. The concept of in situ recovery of material can lead to more advances in maintaining the cycle life of RFBs in the future.

  9. Effect of Vanadium and Molybdenum on the Crystallization, Microstructure and Properties of Hypoeutectic Silumin

    Directory of Open Access Journals (Sweden)

    Szymczak T.

    2015-12-01

    Full Text Available The paper presents the results of hypoeutectic silumin 226 grade and silumin produced on its basis through the addition of V and Mo. Vanadium and molybdenum were added as the preliminary alloy AlV10 and AlMo8 in an amount providing the concentration of 0.1; 0.2; 0.3 and 0.4% V and Mo. TDA curves of tested silumins were presented; regardless of the chemical composition there were similar thermal effects. Pressure castings microstructure research revealed the presence in silumins with the addition of V and Mo phases do not occur in silumin without these additives. These phases have a morphology similar to the walled, and their size increases with increasing concentration of V and Mo. The size of the precipitates of these phases silumin containing 0.1% V and Mo does not exceed 10 microns, while 0.4% of the content of these elements increases to about 80 microns. Tests of basic mechanical properties of silumins were carried out. It has been shown that the highest values of tensile strength Rm = 295 MPa and elongation A = 4.2% have silumin containing approximately 0.1% V and Mo. Increasing concentrations of these elements causes a gradual lowering of the Rm and A values.

  10. Vanadium carbide and graphite promoted Pd electrocatalyst for ethanol oxidation in alkaline media

    Science.gov (United States)

    Yan, Zaoxue; Zhang, Mingmei; Xie, Jimin; Shen, Pei Kang

    2013-12-01

    The vanadium carbide particles with the diameter of 1-3 nm on graphitized resin (GC-V8C7) are synthesized through ionic exchange process. The materials are characterized by XRD, Raman, TEM, SEM and EDS measurements. The results prove that the ion-exchange resin as both carbon source and dispersion media favors the formation of very uniform and small (1-3 nm) V8C7 particles, and protect the V8C7 from conglomeration even at the temperature of 1500 °C. Meanwhile, the vanadium compound is found efficient catalytic effect on graphitization of ion-exchange resin, leading to high graphitization degree of GC-V8C7. Pd particles are loaded on the GC-V8C7 materials as electrocatalyst (Pd/GC-V8C7) for ethanol oxidation in alkaline media. The cyclic voltammograms measurements show that both V8C7 and GC (graphitized ion-exchange resin) give Pd electrocatalyst improved catalytic performance in activity, stability and overpotential, compared with that of Pd supporting on Vulcan XC-72 carbon (Pd/C). The present synthesizing method of GC-V8C7 is simple and effective, which can be readily scaled up for mass production of other nanomaterials.

  11. Modulatory role of vanadium on trace element profile in diethylnitrosamine-induced rat hepatocarcinogenesis

    Science.gov (United States)

    Chakraborty, A.; Selvaraj, S.; Sudarshan, M.; Dutta, R. K.; Ghugre, S. S.; Chintalapudi, S. N.

    2000-09-01

    Particle-induced X-ray emission (PIXE) analysis was employed in the present study to investigate the chemopreventive potential of vanadium in influencing trace elemental profile and antioxidant status in chemical carcinogenesis. The elements with Z=15-40 were studied. Data reveal remarkable alterations in elemental composition in the hepatic tissue of diethylnitrosamine (DENA)-induced Sprague-Dawley male rats (intraperitoneal (ip) dose: 200 mg/kg body weight) after four weeks of induction. Several elements like Mn, Cu, Zn, Rb showed large depletion while other elements like Fe, Ca, K, Br showed large enhancement in comparison to that of the normal control animals. These elements compete for binding sites in the cell, change its enzymatic activity and exert direct or indirect action on the carcinogenic process. Supplementary vanadium (0.5 ppm ad libitum in drinking water) has shown effective modulation by alteration in the concentration of trace elements in the tumorigenic tissue ( Phomeostasis, a parameter of importance in cancer prevention research.

  12. Preparation of silicon carbide-supported vanadium oxide and its application of removing NO by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zi-Bo; Xu, Xu [Yangzhou University, College of Environmental Science and Engineering, Yangzhou, Jiangsu (China); Bai, Shu-Li [Wuyi University, College of Chemical and Environmental Engineering, Jiangmen, Guangdong (China); Guan, Yu-Jiang; Jiang, Sheng-Tao [Taizhou University, Environmental Engineering, Taizhou, Zhejiang (China)

    2017-03-15

    The aim of this work was to study the preparation of SiC-supported V{sub 2}O{sub 5} catalysts and the kinetics on selective catalytic reduction for NO with NH{sub 3} on the catalysts. Using incipient wetness impregnation methods, vanadium oxide was applied to silicon carbide to prepare a SiC-supported vanadium oxide. X-ray photoelectron spectroscopy analysis confirmed that V{sub 2}O{sub 5} existed in the prepared materials. Using the prepared materials as catalysts, selective catalytic reduction for NO by NH{sub 3} has been analyzed, and reaction kinetics on the catalysts was studied at 150-300 C. The obtained results showed that the reduction reaction on the catalysts is close to zero-order kinetics with respect to NH{sub 3}, first-order with respect to NO, and half-order to O{sub 2}. Apparent activation energy for the reduction reaction was found to be 38 kJ mol{sup -1}. The prepared materials are stable and reusable. (orig.)

  13. Influence of doping on the properties of vanadium oxide gel films

    Energy Technology Data Exchange (ETDEWEB)

    Pergament, A L; Velichko, A A; Berezina, O Ya; Kazakova, E L; Kuldin, N A; Artyukhin, D V [Physics and Technology Department, Petrozavodsk State University, Petrozavodsk 185910 (Russian Federation)], E-mail: aperg@psu.karelia.ru

    2008-10-22

    The effect of doping with H and W on the properties of V{sub 2}O{sub 5} and VO{sub 2} derived from V{sub 2}O{sub 5} gel has been studied. It is shown that the treatment of V{sub 2}O{sub 5} in low-temperature RF hydrogen plasma for 1-10 min leads to either hydration of vanadium pentoxide or its reduction (depending on the treatment conditions) to lower vanadium oxides. For some samples, which are subject to plasma treatment in the discharge active zone, a non-ordinary temperature dependence of resistance, with a maximum at T{approx}100 K, is observed. For W-doped VO{sub 2} films, it is shown that substitution of V{sup 4+} with W{sup 6+} results in a decrease of the temperature of the metal-insulator transition. Also, it has been shown that the doping of initial films with {approx}3 at.% of W reduces the statistical scatter in the threshold parameters of the switching devices with S-shaped I-V characteristics on the basis of V{sub 2}O{sub 5} gel films. (fast track communication)

  14. Oxidation of zirconium alloys in 2.5 kPa water vapor for tritium readiness.

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Bernice E.

    2007-11-01

    A more reactive liner material is needed for use as liner and cruciform material in tritium producing burnable absorber rods (TPBAR) in commercial light water nuclear reactors (CLWR). The function of these components is to convert any water that is released from the Li-6 enriched lithium aluminate breeder material to oxide and hydrogen that can be gettered, thus minimizing the permeation of tritium into the reactor coolant. Fourteen zirconium alloys were exposed to 2.5 kPa water vapor in a helium stream at 300 C over a period of up to 35 days. Experimental alloys with aluminum, yttrium, vanadium, titanium, and scandium, some of which also included ternaries with nickel, were included along with a high nitrogen impurity alloy and the commercial alloy Zircaloy-2. They displayed a reactivity range of almost 500, with Zircaloy-2 being the least reactive.

  15. Tensile and impact properties of General Atomics 832864 heat of V-4Cr-4Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Nowicki, L.J.; Gazda, J.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States); Johnson, W.R.; Trester, P. [General Atomics, San Diego, CA (United States)

    1998-09-01

    A 1300-kg heat of V-4Cr-4Ti alloy was procured by General Atomics (GA) for the DIII-D radiative divertor program. To determine the mechanical properties of this alloy, tensile and Charpy tests were conducted on specimens prepared from pieces of 4.8-mm-thick as-rolled plates, a major product form for the DIII-D application. The tensile tests were conducted at three temperatures, 26, 280 and 380 C, the last two being the anticipated peak temperatures during DIII-D boronization and postvent bake-out, respectively. Results from these tests show that the tensile and impact properties of the 832864 heat are comparable to those of the other smaller V-(4-5)Cr-(4-5)Ti alloy heats previously developed by the US Fusion Materials Program and that scale-up of vanadium alloy production can be successfully achieved as long as reasonable process control is implemented.

  16. Thermally activated formation of martensite in Fe-C alloys and Fe-17%Cr-C stainless steels during heating from boiling nitrogen temperature

    DEFF Research Database (Denmark)

    Villa, Matteo; Hansen, Mikkel Fougt; Somers, Marcel A. J.

    2016-01-01

    The thermally activated austenite-to-martensite transformation was investigated by magnetometry in three Fe-C alloys and in two 17%Cr stainless steels. After quenching to room temperature, samples were immersed in boiling nitrogen and martensite formation was followed during subsequent (re)heating......-dependent transformation curve. Moreover, magnetometry showed that the heating rate had an influence on the fraction of martensite formed during sub-zero Celsius treatment. The activation energy for thermally activated martensite formation was quantified in the range 11‒21 kJ/mol by a Kissinger-like method....... to room temperature. Different tests were performed applying heating rates from 0.5 K/min to 10 K/min. An additional test consisted in fast (re)heating the samples by immersion in water. Thermally activated martensite formation was demonstrated for all investigated materials by a heating rate...

  17. The Effect of Active Phase of the Work Material on Machining Performance of a NiTi Shape Memory Alloy

    Science.gov (United States)

    Kaynak, Yusuf; Karaca, Haluk E.; Noebe, Ronald D.; Jawahir, I. S.

    2015-06-01

    Poor machinability with conventional machining processes is a major shortcoming that limits the manufacture of NiTi components. To better understand the effects of phase state on the machining performance of NiTi alloys, cutting temperature, tool-wear behavior, cutting force components, tool-chip contact length, chip thickness, and machined surface quality data were generated from a NiTi alloy using precooled cryogenic, dry, minimum quantity lubrication (MQL), and preheated machining conditions. Findings reveal that machining NiTi in the martensite phase, which was achieved through precooled cryogenic machining, profoundly improved the machining performance by reducing cutting force components, notch wear, and surface roughness. Machining in the austenite state, achieved through preheating, did not provide any benefit over dry and MQL machining, and these processes were, in general, inferior to cryogenic machining in terms of machining performance, particularly at higher cutting speeds.

  18. Phenolic Modified Ceramic Coating on Biodegradable Mg Alloy: The Improved Corrosion Resistance and Osteoblast-Like Cell Activity

    Directory of Open Access Journals (Sweden)

    Hung-Pang Lee

    2017-06-01

    Full Text Available Magnesium alloys have great potential for developing orthopedic implants due to their biodegradability and mechanical properties, but the rapid corrosion rate of the currently-available alloys limits their clinical applications. To increase the corrosion resistance of the substrate, a protective ceramic coating is constructed by a micro-arc oxidation (MAO process on ZK60 magnesium alloy. The porous ceramic coating is mainly composed of magnesium oxide and magnesium silicate, and the results from cell cultures show it can stimulate osteoblastic cell growth and proliferation. Moreover, gallic acid, a phenolic compound, was successfully introduced onto the MAO coating by grafting on hydrated oxide and chelating with magnesium ions. The gallic acid and rough surface of MAO altered the cell attachment behavior, making it difficult for fibroblasts to adhere to the MAO coating. The viability tests showed that gallic acid could suppress fibroblast growth and stimulate osteoblastic cell proliferation. Overall, the porous MAO coating combined with gallic acid offered a novel strategy for increasing osteocompatibility.

  19. Kinetic-spectrophotometric determination of trace amounts of vanadium(V) based on its catalytic effect on the reaction of DBM-arsenazo and potassium bromate

    Science.gov (United States)

    Zhai, Qing-zhou; Zhang, Xiao-xia; Huang, Chong

    2008-03-01

    A simple and sensitive kinetic-spectrophotometric method is developed for the determination of trace vanadium(V), based on the catalytic effect of vanadium(V) on the oxidation of DBM-arsenazo by potassium bromate in 0.0138 mol l -1 phosphoric acid medium and at 100 °C in the presence of citric acid as activator. The absorbance is measured at 528 nm with the fixed-time method. The optimization of the operating conditions regarding concentrations of the reagents, temperature and interferences are also investigated. The working curve is linear over the concentration range 0-20 ng ml -1 of vanadium(V) with good precision and accuracy and the detection limit was down to 3.44 ng l -1. The relative standard deviation for a standard solution of 14 ng ml -1 is 0.28% ( n = 11). The apparent activity energies of the catalytic reaction and the non-catalytic reaction are 73.48, 113.5 kJ/mol, respectively. The proposed method proved highly sensitive, selective and relatively rapid for the assay of vanadium at low-level range of 0-20 ng ml -1 without any pre-concentration step. Thw method was applied to the determination of vanadium(V) in steels, rice, flour, cabbage, potato, fish, shrimp and tea samples with satisfactory results. The obtained results for the steel samples were excellent agreement with the standard reference values. The analytical results of the rice, flour, cabbage, potato, fish, shrimp and tea samples were excellent agreement with those of atomic absorption spectrometry. The recovery experiments have been made for the rice, flour, cabbage, potato, fish, shrimp and tea samples except the steels; excellent results were obtained. The relative standard deviations were over the range of 0.18-2.60% and the recoveries were over the range of 98.00-102.4%, respectively. The analytical results obtained were satisfactory.

  20. Nanoscale Alloying in Electrocatalysts

    Directory of Open Access Journals (Sweden)

    Shiyao Shan

    2015-08-01

    Full Text Available In electrochemical energy conversion and storage, existing catalysts often contain a high percentage of noble metals such as Pt and Pd. In order to develop low-cost electrocatalysts, one of the effective strategies involves alloying noble metals with other transition metals. This strategy promises not only significant reduction of noble metals but also the tunability for enhanced catalytic activity and stability in comparison with conventional catalysts. In this report, some of the recent approaches to developing alloy catalysts for electrocatalytic oxygen reduction reaction in fuel cells will be highlighted. Selected examples will be also discussed to highlight insights into the structural and electrocatalytic properties of nanoalloy catalysts, which have implications for the design of low-cost, active, and durable catalysts for electrochemical energy production and conversion reactions.

  1. Extraction of Vanadium from Stone Coal by Microwave Assisted Sulfation Roasting

    Science.gov (United States)

    Wang, Mingyu; Xian, Pengfei; Wang, Xuewen; Li, Bowen

    2015-02-01

    The extraction of vanadium from stone coal was investigated by microwave-assisted sulfation roasting followed by water leaching. The results showed that this process is an effective method for the extraction of vanadium from stone coal. Microwave-assisted sulfation roasting promotes the reaction of sulfuric acid with vanadium oxides and decreases roasting time. Under optimized conditions (roasting temperature 200°C, heating rate of 10°C/min, 25% sulfuric acid addition, water leaching at 75°C for 1 h, and liquid/solid ratio of 1.5 ml/g), the leaching rate of vanadium reached 92.6%.

  2. Vanadium accelerates horizontal transfer of tet(M) gene from marine Photobacterium to Escherichia coli.

    Science.gov (United States)

    Suzuki, Satoru; Kimura, Midori; Agusa, Tetsuro; Rahman, Habibur M

    2012-11-01

    Vanadium is a contaminant from steel additive and ship fuel in coastal and port areas, and its effect on marine microbes remains largely unknown. We showed that vanadium accelerates transfer of the tetracycline resistance gene tet(M) from Photobacterium to Escherichia coli, and found a positive correlation between the concentration of vanadium in natural marine sediment and the rate of oxytetracycline resistance. These results suggest the possibility that vanadium may play a role in the preservation and horizontal transfer of antibiotic resistance genes in the marine environment. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  3. Distribution of vanadium and vanadylporphyrines in petroleum fractions of different chemical types

    Energy Technology Data Exchange (ETDEWEB)

    Aleshin, G.N.; Altukhova, Z.P.; Antipenko, V.R.; Marchenko, S.P.; Kam' yanov, V.F.

    Distribution of vanadium among petroleum components: tars, asphaltenes and oils from various levels of Samotlorsk fields was studied. It was shown that the predominant fraction of vanadium and vanadyl porphyrines is concentrated in petroleum tars. The highest absolute concentration of V was noted in the asphaltene fraction; however, vanadium atoms were found to be bound to heteroatomic fragments of the tarry-asphaltene compounds. Up to 98% of vanadium contained in asphaltenes and almost all V atoms in oil fractions are bound by non-porphyrinyl compounds. With increased methanization of the petroleum fractions, their V content drops rapidly. 5 references, 2 figures.

  4. Exploring the chemistry and biology of vanadium-dependent haloperoxidases.

    Science.gov (United States)

    Winter, Jaclyn M; Moore, Bradley S

    2009-07-10

    Nature has developed an exquisite array of methods to introduce halogen atoms into organic compounds. Most of these enzymes are oxidative and require either hydrogen peroxide or molecular oxygen as a cosubstrate to generate a reactive halogen atom for catalysis. Vanadium-dependent haloperoxidases contain a vanadate prosthetic group and utilize hydrogen peroxide to oxidize a halide ion into a reactive electrophilic intermediate. These metalloenzymes have a large distribution in nature, where they are present in macroalgae, fungi, and bacteria, but have been exclusively characterized in eukaryotes. In this minireview, we highlight the chemistry and biology of vanadium-dependent haloperoxidases from fungi and marine algae and the emergence of new bacterial members that extend the biological function of these poorly understood halogenating enzymes.

  5. Exploring the Chemistry and Biology of Vanadium-dependent Haloperoxidases*

    Science.gov (United States)

    Winter, Jaclyn M.; Moore, Bradley S.

    2009-01-01

    Nature has developed an exquisite array of methods to introduce halogen atoms into organic compounds. Most of these enzymes are oxidative and require either hydrogen peroxide or molecular oxygen as a cosubstrate to generate a reactive halogen atom for catalysis. Vanadium-dependent haloperoxidases contain a vanadate prosthetic group and utilize hydrogen peroxide to oxidize a halide ion into a reactive electrophilic intermediate. These metalloenzymes have a large distribution in nature, where they are present in macroalgae, fungi, and bacteria, but have been exclusively characterized in eukaryotes. In this minireview, we highlight the chemistry and biology of vanadium-dependent haloperoxidases from fungi and marine algae and the emergence of new bacterial members that extend the biological function of these poorly understood halogenating enzymes. PMID:19363038

  6. A novel process for comprehensive utilization of vanadium slag

    Science.gov (United States)

    Liu, Li-ying; Du, Tao; Tan, Wen-jun; Zhang, Xin-pu; Yang, Fan

    2016-02-01

    Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas, which cause serious environmental problems. In this study, a new process for the comprehensive utilization of vanadium slag was proposed, wherein zeolite A and a V2O5/TiO2 system were synthesized. The structural properties of the as-synthesized zeolite A and the V2O5/TiO2 system were characterized using various experimental techniques, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and infrared spectroscopy. The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity. The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.

  7. Study of sulfur and vanadium in heavy petroleum products

    Energy Technology Data Exchange (ETDEWEB)

    Novelli, J.M.

    1982-10-01

    Sulfur compounds in heavy oil fractions (>450/sup 0/C) are studied in the first part of this work. After chemical oxidation by metachloroperbenzoic acid to obtain sulfones, sulfur compounds are analyzed by infrared spectroscopy for their qualitative and quantitative repartition. The method can be applied for the study of sulfur containing molecules before and after structural modifications of petroleum fractions by any chemical refining processes. In a second part vanadium is characterized in asphalt by physicochemical and chemical methods. 80% of the vanadium in a Boscan asphalt is under the form of porphyrins. Different associations are evidenced in petroleum fractions and metalloporphyrins, but the liaison between the vanadyl group and heterocondensate from asphalts is the more frequent.

  8. Spectrophotometric determination of catecholamine using vanadium and eriochrome cyanine r

    Energy Technology Data Exchange (ETDEWEB)

    Nagaraja, Padmarajaiah; Shrestha, Ashwinee Kumar; Shivakumar, Anantharaman; Al-Tayar, Naef Ghallab Saeed; Gowda, Avinask K., E-mail: profpn58@yahoo.co [University of Mysore, Manasagangotri (India). Dept. of Studies in Chemistry

    2011-07-01

    highly sensitive spectrophotometric method for the analysis of catecholamine drugs; L-dopa and methyldopa, is described. The analysis is based on the reaction of drug molecules with vanadium (V) which is reduced to vanadium (IV) and form complex with eriochrome cyanine R to give products having maximum absorbance ({lambda}{sub max}) at 565 nm. Beer's law is obeyed in the range 0.028-0.84 and 0.099-0.996 {mu}g mL{sup -1} for L-dopa and methyldopa, respectively. The statistical analysis as well as comparison with reported methods demonstrated high precision and accuracy of the proposed method. The method was successfully applied in the analysis of pharmaceutical preparations. (author)

  9. High temperature hardness of steels and iron-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Torres, H., E-mail: torres@ac2t.at; Varga, M.; Ripoll, M. Rodríguez

    2016-08-01

    Hot hardness, related to the mechanical strength and wear resistance of materials at high temperatures, has been measured from room temperature up to 800 °C for a comprehensive set of iron-based alloys having different microstructures and chemical compositions. The results obtained suggest the existence of several softening regimes with increasing temperatures, also with a massive hardness drop observed to begin at temperatures close to 0.5 times the melting temperature for most of the chosen alloys. Austenitic steel grades were also observed to show a significant softening behaviour at moderate temperatures compared to ferritic and martensitic alloys, attributed to the dislocation dynamics of face cubic centred alloys. The exact nature of the temperature dependence shown by hardness has been proposed to adopt the form of an exponential Arrhenius equation. Another model suggested in the available literature is also discussed within this context. Additionally, the role of alloying elements has been correlated to the softening behaviour. Molybdenum or boron were found to slow down the softening behaviour, while carbide-forming elements such as vanadium and tungsten were found to be beneficial for room temperature hardness.

  10. Speciation of Chromium and Vanadium in Medicinal Plants ...

    African Journals Online (AJOL)

    In this study, Cr(VI) and V(V) were determined in medicinal plants collected from the farm located between two smelters. Chromium(VI) and vanadium(V) were leached from medicinal plants with 0.1 M Na2CO3 prior their determination by ETAAS. The concentration of Cr(VI) in medicinal plants varied between 3.1 ± 0.5 μg ...

  11. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Abstract. Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3(x). ZnO(40−x)V2O5(60)(where x = 0·1–0·5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been ...

  12. Acute toxicity of vanadium to two species of freshwater fish

    Energy Technology Data Exchange (ETDEWEB)

    Knudtson, B.K.

    1979-09-01

    Goldfish (Carassius auratus) and guppies (Lebistes reticulatus) were the two freshwater, thermophilous fishes chosen for use in this study. These species were selected for the following reasons: (1) low cost/individual, (2) ready availability, (3) ease of care and handling, (4) suspected differences between the two species in their responses to this metal, and (5) the usefulness of both as generalized models for the response of freshwater and marine fishes to vanadium.

  13. Spleen and bone marrow megakaryocytes as targets for inhaled vanadium

    OpenAIRE

    Teresa I Fortoul; Piñón-Zarate, Gabriela; Diaz-Bech, María Eugenia; González-Villalva, Adriana; Mussali-Galante, Patricia; Rodriguez-Lara,Vilaney; Colin-Barenque, Laura; Martinez Pedraza, Michelle; Luis F. Montaño

    2008-01-01

    An increased incidence in ischemic and thromboembolic events in the population of cities with rising air suspended particle pollution has suggested the interaction of some of the components of these particles in the coagulation system. A previous report from our laboratory identified thrombocytosis as a consequence of the subacute and chronic inhalation of vanadium. With this preceding information we decided to evaluate the effects of this element in the spleen and bon...

  14. Microstructure Evolution and High-Temperature Compressibility of Modified Two-Step Strain-Induced Melt Activation-Processed Al-Mg-Si Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Chia-Wei Lin

    2016-05-01

    Full Text Available A two-step strain-induced melt activation (TS-SIMA process that omits the cold working step of the traditional strain-induced melt activation (SIMA process is proposed for 6066 Al-Mg-Si alloy to obtain fine, globular, and uniform grains with a short-duration salt bath. The results show that increasing the salt bath temperature and duration leads to a high liquid phase fraction and a high degree of spheroidization. However, an excessive salt bath temperature leads to rapid grain growth and generates melting voids. The initial degree of dynamic recrystallization, which depends on the extrusion ratio, affects the globular grain size. With an increasing extrusion ratio, the dynamic recrystallization becomes more severe and the dynamic recrystallized grain size becomes smaller. It results in the globular grains becomes smaller. The major growth mechanism of globular grains is Ostwald ripening. Furthermore, high-temperature compressibility can be improved by the TS-SIMA process. After a 4 min salt bath at 620 °C, the high-temperature compression ratio become higher than that of a fully annealed alloy. The results show that the proposed TS-SIMA process has great potential.

  15. Dehydrogenation of Isobutane with Carbon Dioxide over SBA-15-Supported Vanadium Oxide Catalysts

    Directory of Open Access Journals (Sweden)

    Chunling Wei

    2016-10-01

    Full Text Available A series of vanadia catalysts supported on SBA-15 (V/SBA with a vanadia (V content ranging from 1% to 11% were prepared by an incipient wetness method. Their catalytic behavior in the dehydrogenation of isobutane to isobutene with CO2 was examined. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, and temperature-programmed reduction (TPR. It was found that these catalysts were effective for the dehydrogenation reaction, and the catalytic activity is correlated with the amount of dispersed vanadium species on the SBA-15 support. The 7% V/SBA catalyst shows the highest activity, which gives 40.8% isobutane conversion and 84.8% isobutene selectivity. The SBA-15-supported vanadia exhibits higher isobutane conversion and isobutene selectivity than the MCM-41-supported one.

  16. A combined theoretical-experimental study of interactions between vanadium ions and Nafion membrane in all-vanadium redox flow batteries

    Science.gov (United States)

    Intan, Nadia N.; Klyukin, Konstantin; Zimudzi, Tawanda J.; Hickner, Michael A.; Alexandrov, Vitaly

    2018-01-01

    Vanadium redox flow batteries (VRFBs) are a promising solution for large-scale energy storage, but a number of problems still impede the deployment of long-lifetime VRFBs. One important aspect of efficient operation of VRFBs is understanding interactions between vanadium species and the membrane. Herein, we investigate the interactions between all four vanadium cations and Nafion membrane by a combination of infrared (IR) spectroscopy and density-functional-theory (DFT)-based static and molecular dynamics simulations. It is observed that vanadium species primarily lead to changes in the IR spectrum of Nafion in the SO3- spectral region which is attributed to the interaction between vanadium species and the SO3- exchange sites. DFT calculations of vanadium -Nafion complexes in the gas phase show that it is thermodynamically favorable for all vanadium cations to bind to SO3- via a contact pair mechanism. Car-Parrinello molecular dynamics-based metadynamics simulations of cation-Nafion systems in aqueous solution suggest that V2+ and V3+ species coordinate spontaneously to SO3-, which is not the case for VO2+ and VO2+. The interaction behavior of the uncycled membrane determined in this study is used to explain the experimentally observed changes in the vibrational spectra, and is discussed in light of previous results on device-cycled membranes.

  17. The toxicity of vanadium on gastrointestinal, urinary and reproductive system, and its influence on fertility and fetuses malformations

    Directory of Open Access Journals (Sweden)

    Aleksandra Wilk

    2017-09-01

    Additionally, this research identifies the doses of vanadium which lead to pathological alterations becoming visible within tissues. Moreover, this study includes information about the protective efficacy of some substances in view of the toxicity of vanadium.

  18. Criticality of iron and its principal alloying elements.

    Science.gov (United States)

    Nuss, Philip; Harper, E M; Nassar, N T; Reck, Barbara K; Graedel, T E

    2014-04-01

    Because modern technology depends on reliable supplies of a wide variety of materials and because of increasing concern about those supplies, a comprehensive methodology was created to quantify the degree of criticality of the metals of the periodic table. In this paper, we apply this methodology to iron and several of its main alloying elements (i.e., vanadium, chromium, manganese, and niobium). These elements represent the basic metals of any industrial society and are vital for national security and economic well-being. Assessments relating to the dimensions of criticality - supply risk, vulnerability to supply restriction, and environmental implications - for 2008 are made on the global level and for the United States. Evaluations of each of the multiple indicators are presented, with aggregate results plotted in "criticality space", together with Monte Carlo simulation-derived "uncertainty cloud" estimates. Iron has the lowest supply risk, primarily because of its widespread geological occurrence. Vanadium displays the highest cradle-to-gate environmental implications, followed by niobium, chromium, manganese, and iron. Chromium and manganese, both essential in steel making, display the highest vulnerability to supply restriction, largely because substitution or substitution at equal performance is not possible for all end-uses. From a comprehensive perspective, we regard the overall criticality as low for iron and modest for the alloying elements we evaluated.

  19. Role of alloying elements in adhesive transfer and friction of copper-base alloys

    Science.gov (United States)

    Buckley, D. H.

    1978-01-01

    Sliding friction experiments were conducted in a vacuum with binary-copper alloy riders sliding against a conventional bearing-steel surface with normal residual oxides present. The binary alloys contained 1 atomic percent of various alloying elements. Auger spectroscopy analysis was used to monitor the adhesive transfer of the copper alloys to the bearing-steel surface. A relation was found to exist between adhesive transfer and the reaction potential and free energy of formation of the alloying element in the copper. The more chemically active the element and the more stable its oxide, the greater was the adhesive transfer and wear of the copper alloy. Transfer occurred in all the alloys except copper-gold after relatively few (25) passes across the steel surface.

  20. Preparation and Localization of a Monoclonal Antibody against a Vanadium-Associated Protein Extracted from the Blood Cells of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea

    OpenAIRE

    Junko, Wuchiyama; Yasuhiro, Nose; Taro, Uyama; Hitoshi, Michibata; Mukaishima Marine Biological Laboratory, Faculty of Science and Laboratory of Marine Molecular Biology, Graduate School of Science, Hiroshima University

    1997-01-01

    Ascidians are known to accumulate high levels of vanadium in their blood cells, Recently, we found a vanadium-associated protein (VAP) in blood cells of a vanadium-rich ascidian, Ascidia sydneiensis samea. In this paper, we raised a monoclonal antibody against VAP, designated F8DH. Immunoblot analysis showed that F8DH recognized 2 related peptides of 15 kDa and 16 kDa of VAP. Using F8DH, VAP was shown to be in the cytoplasm of vanadocytes and compartment cells, both of which were reported to ...